CA2222414A1 - Apparatus for igniting a propellant charge in a tool - Google Patents
Apparatus for igniting a propellant charge in a tool Download PDFInfo
- Publication number
- CA2222414A1 CA2222414A1 CA002222414A CA2222414A CA2222414A1 CA 2222414 A1 CA2222414 A1 CA 2222414A1 CA 002222414 A CA002222414 A CA 002222414A CA 2222414 A CA2222414 A CA 2222414A CA 2222414 A1 CA2222414 A1 CA 2222414A1
- Authority
- CA
- Canada
- Prior art keywords
- propellant
- charge
- combustion chamber
- tool
- driver
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25C—HAND-HELD NAILING OR STAPLING TOOLS; MANUALLY OPERATED PORTABLE STAPLING TOOLS
- B25C1/00—Hand-held nailing tools; Nail feeding devices
- B25C1/08—Hand-held nailing tools; Nail feeding devices operated by combustion pressure
- B25C1/10—Hand-held nailing tools; Nail feeding devices operated by combustion pressure generated by detonation of a cartridge
- B25C1/14—Hand-held nailing tools; Nail feeding devices operated by combustion pressure generated by detonation of a cartridge acting on an intermediate plunger or anvil
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25C—HAND-HELD NAILING OR STAPLING TOOLS; MANUALLY OPERATED PORTABLE STAPLING TOOLS
- B25C1/00—Hand-held nailing tools; Nail feeding devices
- B25C1/08—Hand-held nailing tools; Nail feeding devices operated by combustion pressure
- B25C1/082—Hand-held nailing tools; Nail feeding devices operated by combustion pressure generated by detonation of a pellet
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25C—HAND-HELD NAILING OR STAPLING TOOLS; MANUALLY OPERATED PORTABLE STAPLING TOOLS
- B25C1/00—Hand-held nailing tools; Nail feeding devices
- B25C1/08—Hand-held nailing tools; Nail feeding devices operated by combustion pressure
- B25C1/10—Hand-held nailing tools; Nail feeding devices operated by combustion pressure generated by detonation of a cartridge
- B25C1/16—Cartridges specially adapted for impact tools; Cartridge and bolts units
- B25C1/166—Pellets
Abstract
A tool for driving a nail or other fastener is actuated by a caseless propellant charge (62) formed of combustible material that is transported into a combustion chamber (44) on a strip (64). The propellant charge (62) is ignited by striking a sensitizer portion (90) of the charge at an oblique angle. The ignition member (66) intermixes the sensitizer material (90) with an oxidizer layer (88) of the surface of the propellant charge (62), resulting in combustion of the charge. When ignited, the propellant charge (62) is compressingly interposed between an orifice plate (74) and a movable portion (80) of the combustion chamber. The orifice plate (74) includes a pedestal (78) with an annular compression surface that separates the surface of the ignition area from the remaining surfaces of the charge (62); insuring that ignition gases are forced through the charge (62). An annular C-shaped ring (82) is interposed between the orifice plate (74) and the movable portion (80) of the combustion chamber (44). When the charge (62) is ignited, the resulting gas pressure resiliently expands the annular C-shaped ring (82) and urges opposite axial ends of the C-shaped ring (82) into sealing relationship between the relatively movable components of the combustion chamber. Combustion gases are communicated through orifices (76) in the orifice plate (74) to a cylinder (40) where the gases force movement of a driver (42), which driver strikes and drives a fastener such a nail. The driver (42) is reciprocally movable within the cylinder (40) and is returned to its precombustion position by a gas spring return cylinder (17). The gas return cylinder (17) is mechanically interconnected to the driver (42) and contains a sealed gaseous fluid that is independent of and segregated from fluids in the combustion chamber (44). An assembly (60) for deaccelerating the driver includes a series of spaced and aligned progressively sized metal cup members (110, 112, 114) of progressively increasing mass, contact surface area and interface angles.
Description
~ W O 96/39283 PCT.~596~$~9Q
APPARATUS FOR rG~G A PROPE~ANT CHA~E IN A TdO~
T~C~CAL FIELI:2 The preser~ i~ve~h~rL i~ d~rected ~n~r~lly to dnvi~ taQl~ a~ mare particularly, to propellant dnv~ng tools of the type which use prqpellant charges to drive a f~ n~ or ot~ c~ect. The iIIventiar~ wilL ~e sE~ec~caLly di~ciased co~nectiorI w~th a driv~rrg taal that ig~ites a c seless propelIant charge artd uses the resultiIlg combustion gases to drive a nail.
BACKGROU~D OF THE I~VEi'1TIO~
The majorily of the fastener drivin~J tools in use today are pneumalically powered. I',-~."~ t~Qls u~ saurce af ~.~uLL~cd ~ tha~ is sttrt~iie~ t~ the t~l through ~ hose. l~is is a severe limit~ri~n on the versatilily of pnel-m~tic tools;
they must be tied to a saurce of air pres$ure by a hose, limitinG the distance which 1~ the tQols r~n be moved fram the air sourc-. In ~*~itinn, s~rne rem~te Jo~ sit~s make ir difficult to provide an easily accessible and economical air source. Theadded e~pense of providin~ electrical service to power the air source, or usin~
alternative power sources (such as ~Jasoline powered compressors) for providin~ the compressed air, subtract from the efficiency and convenience that pneumatic tools '70 traditionaLly provide. Therefore, there have becen many altempts to provide alternarives to pnellm~tic~lly acm~ d tools that can be used in sit~l~ti~n~ where the ;c ~s ~e ~ot ~ Y~r~
Q~e ~It.~ .y~ t~ e~e~ap~ ic a ~al w~c~ e~ .y ta provide the power needed to drive fasteners of the type and size that traditionally pneumatic tools drive. Most of these tools use an electric motor to power one ormore flvwhe_ls which, in turn, store suff~cient ener~y to drive the fasreners.
E~arnples of these tools are set forrh in U.S. Patent Nos. 4,04~,036; 4,1~1,745;
OEQ ~E~
- WQ ~61~9~ PC~l:.'US96/')~3''9Q
4,204,6Z2; 4,298,072; 4,32~ 7; and 4,~4,5i~. Hawever, t~ese taols st~ll suffer from the same timit~ti~lll as the pn~lm~tic tools in tha~ they must be cnnn~cte~ by a cor~ tQ an energy 5Q~C~
A secand ~it~ ;y;~ which has ref ~:ntLy beerL d~velaped i~ a e9mpl~t~1y 5elf-cnnt~ined fastener driving tool which is powered by internal combustion of a ~c.~ c fuel-air mixalre. E,~mples of these tools are fallnd i~ U S Pa~t Nas.
Z,898,8g3; 3~,042,(~05; ~,7I~,608; 3,gS0,359; 4,075,850; 4,zoo,zr,; 4,ZIg,g8g;
4,403,7'7'7; 4,415,110; and 4,7~,91~. While these tools need no connection to ane~temal power source and are e~remely versatile, they tend to be somewhat large,comple~, heavy and awlcward to use. In addition, they c n be less economical to operate in that the fuel used is relatively e~pensive.
Anatiter ciass ~}f tco~ is ~ y used ~c a~ t~
I~ pneumatic tools is the powder or propellant actuated tOOl. Powder or propellant act~-~ted fastener driving tools are used most fre~uently for driving fasteners into hard sl~nc~Pc 5uch a~ cc~cre~e The mcs~ comn~tn types ~ s~ch tools are tradi~ionally sin~le fastener, sin~le shot devices; that is, a sin~le fasteners is m~nl-~lly inserted into the barrel of the tool, alon~ with a sin~le propellant char~e.
After the fastener is dischar ed, the tool must be m~n~ 1y reloaded with both a fastener and a propellant char~e in order to be operated a~Jain. E:~arnples of such tools are described in U.S. Patent Nos. 4,830,254; 4,598,851; and 4,577,793.
Tn nro~lT~nt a~c~ t~d tccls, thar9 1~0--~y dif~rent type Or c~ gec ~ed fcr Fropall~+~. Fcr ~ n~ , '~r.S. ~ L ~0. 3,37'~,6A. +~clQ~la 1 lC~r CXF10~ c 2r;~ e fL '~ ,f L ..,',, .. ~.ry ,~ ~&~ t~S~95 n igniter pc.~ion nd hQving Q ~cb thicl~ncss lcs., th~n QQy other dirne~ion cf the pellct. I,r.S. I'Qtcnt ~rO. 3,5~J,518 i~, dirc_tcd to ~ po~dcr crLr~idg9 consisting ~f ~ r~Ticige c~se ccrstrl~c~ of t~o scp~tc piecs~ which cont ir ~ c~"+~l F~i3~er ~acei~ charnber ~ld fr. ~nr~ rroFoll;~t recei~ing ch~rnbsr. U.S. P~t~+ Nro 'NDED SfIEET
U.S. ~a~r~t Na. 3~,g7~ is c~ir~ctec~t~ a r~ r ~ri~ng tao~ USTrrg caseless propellant char~es which has a body, said body defining a 5 combustiorl chamber, anct a cylinder in fluid communication with the combustion chamber, the combustion chamber being at least partially formed by a flrst mern~er and a sec~nd rnember th~ ~re m~vable relative tQ
eact~ ottler.
0 In propellant ~ctl l~ted tcQls, there are many different types of cartrid~es used fcr pr~pellar~s. ~r exarnpLe, ~I.S. Patent Na. 3, 3~2,64:~
teaches a low explosive primerless charge consisting of a substantially resilient fibrous nitrocellulose pellet with an igniter portion and having a webthickness less than any other dimension of the pellet. U.S. Patent No.
- 15 3,529,548 is directed to a powder cartridge consisting of a cartridge case constructed of two separate pieces which contains a central primer receiving chamber and an annular propellant receiving chamber. U.S. Patent No.
3,911,825 discloses a propellant charge having an H-shaped cross section composed of a primer igniter charge surrounded by an annular propellant powder charge. EP560~83A is directed to a caseless pr~pettant charge for use in a fastener dri~fin~ toot, where the tc~l c~mpr;ses a bcdy defin;ng a ccmbustiort chamber ~nd fluid ct[amher, me~Ens f~r pasitioning a caseless propellant charge at a predetermined location in the combustion chamber, and an ignition member mounted within the body, with the ignition member being operative tQ stril~e the propellant charge and to apply a shearing force a~ainst the ~urface cf a propeliant charge when the prcpellant char~e is in the predetermined position.
AMENDED SHEET
; CA 02222414 1997-11-26 ~ W O 9~9283 PC~r~Sn~/f~J
3',~II,8't5 di_clo~~ n propcllcnt ch~rgc hnvin nn ~ hap~d _rocc c~tiorl c~~o~ed of ~ r~ c~ c~ 8 ~d~d by ~n n~ulnr pr~Qll~nt ;~
A second type of powder ~ tt~l taol EIaS 3~so beerL use~ in rece~t times.
'; Ihi~ tcQl etill use~ f~ctf~Tt~s which are irLdivid~ y l~a~ed i~ t~e fIr~'r chamize~
of the device. However, the propellant charges used to provide the energy neededta driYe the f~ct~ or~ ~re ~ravi~P~ a ~ a fl~Yi~1e bar~ af serially ~rr~;nQ~ ;rtn~ ~5 which are fed one-by-ane into the combustion charnber of the tool E,Yamples of this type of tool are taught in U.S. Parent 4,687,1'~6; 4,655,380; and 4,804,1'77 ID
the tools heretofore mentioned, which use a cartridge strip assembly, there are a variety of strips which are available for use. U.S Patent 3,611,870 is directed to a plastic strip in which a series of e~plosive char~Jes are located in recesses in the strip with a press fit ~r S Palent ~a. ~,~5,ISi teaches a cartrid~ stn-p far use with a ~uw~er a~TT~r~* t~al which is ~da~le ~to 2 rall a~aut an a~2s wh~c~ is substantially parallel to the surface portion of the strip and having the propellant cartridges disposed substantially perpendicular to the surface portion. U.S. Pate2t No. ~,675,154 te2che~i a fie~Ee L~ ~;~a~ s~p ~th ~ ec~aes forEIoldir~ rope~a~rt charges, wherein the thickness of the strip corresponds to the length of the charge contained therein. U.S. Patent No. 4,056,062 discloses a strip for carrying a caseless charge wherein the charge is held in the space bv a recess and a tower-shaped wall and is disposed in surface contact with the annular surface within 'the cartridge recess. U.S. Patent No. 4,819,562 describes a propellant cont~in;ng device whichhas a plurality of hollow members closed at one end arld a pluralit,v of closuremeans each having a peripheral rirn which fits into the open end of tne hollow ~75 membess af the device Recently, several powder artll~ted tools have been developed which operate in a manner sirnilar to the traditional pnellm~t;c tools; that is, these devices contain a m~g~7;ne which automaticallv feeds a pluralitv of fasteners serially to the drive D S~EET
W O 96~9283 PCT~US96/08390 charnber of the tool, while a strip of propellant charges is supplied serially to the tool to drive the fasteners.
One example of such a tool is described in U.S. Patent No. 4,821,938. This S patent, which teaches an .~llpl~vt:d version of a tool taught in U.S. Patent No.
4,655,380, is directed to a powder actl-~ted tool with an improved safety interlock which permits a cartridge to be fired only when a safety rod is forced into the barrel and cylinder assembly and when the barrel and cylinder assembly has been forced realw~Ldly into its ~ alw~-l position.
Another exarnple of this type of tool is taught in U.S. Patent No. 4,858,811.
This tool, which is an improved version of the tool taught in U.S. Patent No.
4,687,126, incorporates a handle, a tubular chamber, a piston, and a combustion chamber within the tubular chamber, the combustion chamber receiving a cartridge1~ in preparation for firing, which upon ignition, propels the piston fon,vardly for the driving of a nail. A fastener housing is located forwardly of the tubular chamber, and is provided for directing a strip of fasteners held by a m~7ine upwardly through the tool during repeated tool usage.
Both of the aforementioned recent powder actuated tools, however, are designed to drive fasteners into hard surfaces such as concrete. Consequently, aneed exists for a propellant acnl~ted tool that can be efficiently used as a replacement for traditional pnellm~tic tools which drive fasteners into wood.
It is thus an object of the present invention to ovt:lco-,le the disadvantages of the prior art by providing a propellant ~ct~l~t~d fastener driving tool which is lighter, less complex, and very similar to the traditional pneumatic tool.
- W O 96/39283 PC~,~S~~6/333 It is also an obJect ~f the present invention to provide a tool which c~n be e~~~ily and ~ffCi~ntly used in those wor~~ enviror~mt~ntr; wlle-e rfnpnmAt7~c tGals tr~ Ti*~n~7Tly use It is further a~ Q~e~:t of the pre~e~t inven ar~ ta prGVi~e a s~f~n~t,~in~
fastener driving tool which is safer a~ad less e~pensive to operate than tools currently available and k~aown in the ~
Additional objects, advantacres~ and other novel features of the invention will be set forth in par~ in the description that follows and in parl will become apparent to those skiIled in the arl upon e~Aminrtion of the following orma,v be le~rned with the practice of the invention. The objects and advanta ~es of the invention may be re;llized and ~tt~ b~, me:~ of the iIls~lmpnt~lit;ec ~d rlr~ s~cuiarly E~ir~te~ aut irI ttre ~ cI EmC
Summarv of the Invention To achieve the foregoincr and other objects, and in accordance with the purposesof the present invention disclosed herein, a propellant tool for driving~~n ~t is provided. The tool incllldes a body, a combuslion chamber within the body, means for introducing a caseless propellant char~e into the combustion chamber and for igniting ~ a- f R!~t~
the propellam charge and a cylinder for driving ,~n ~bi~t . An oririce plate is interposed be~ween the combustion chamber and the cylinder. The oririce plale conta7ns a plurality of orifices~for pravidincr fluId commllnication be7ween thecnmhETct;nn chamber and the cyLinder. The orifice-~~ are sized ta ~ Alll;, TTy res~c~
7lnic~nitl~i saI~i ~,u~ ~ ~ the pr~e~anE c~rge from ~ a ~e ~_yl~
orifices preferably have a diameter ~,plo,~,l,ately one-third the length of the average length of the propellant fibers forming the propellant.
AM~ND~3 ~EET
- W O 9~ 83 PE~,~'S9 ~ ~,t~
In another aspect of the invention, a propellant tool for drivmg ~" obj~c~
irlrlllflf~ a 7~dy fif~fi~t;na a ~L~ a f~ f h~m7lf~r ~ ifi f~~ lie~l..)ll w~tk t~e cLJIl~ c~,.m7Jer, me~s for pn~r~;r~ a case~ess propellant charge at a pre~7~tf~tTninf~fl location in the combustion ch~mher an~ a~
i~nirinn member ~ ~t~ the bady ta ~e t~e p.-ope~ t cha~,e at a l obL~e angle and to apply a shearing force against the surface of a propellant charge when the prq;lf 71~nt c harg~ is ir~ tke pre~er-f rTninf~d pQ~i~iQr~ e ianir;on memher pr~:fc.~ly i~
reciprocally movable within the body and operative to pierce the surface of the caseless charge. The caseless propellant charge preferably is forrned of a combustible material, an n~ifli7~r material, and a sPn~iti7~r materi 1, and the piercing of the c~seless charge is operative to mix the combustible, o~idizer and sensitizer materials.
~ r ln accordance with still a~other as7?ect of the invention, a propellant tool for - drivin_ ~n r~ ~r i~r7t~f~toS a E~Qf1Y ~ a t~ U~L ~L~e. irr t~e 7~ad~ for ~,C~
an ignitable propellant charge. The combustion chamber is formed by at least tworelatively movable components that zre operative to receive and compressingly engage - a p~ell~t char~ ~i~ se~i there~e~wee~ e ~ ~e rela~ively m~al~ie Cul~lp~
has an annular compression surface for conr~rr;nc an annular surface area of a propellant charge engaged by the relatively movable components. The armular compression surface separa~es a selected surface area of the propellan~ charge withIn the compression rin~ from the ra~ially ou~ward portions of ~e propellant charge surface. The ~nnular compression surface is operative to restrict gas flow between the selected surface area of the engaged propellant charge from the radially outwardportions of the propellarlt charge surface. An igrlition member contacts the selected surface of the propellant char_e ~ i~tes t~e se~ected area ~ this way, i~n;r;nn gases f~e~ by i"~t'IC~ ~f t}~ Esrg~ c~arge ir~ the SP~ area are fQrre~
through the r~m~;n~r of the charge.
Still other objects of the present invention will become apparent to those s~illed in this art from the following descrip~ion wherein there is shown and described a preferred embodimen~ of this inventiorl, simply by way of illustration, of one of the ~MEI\ID~D S¢fEEr W O 96~9283 PCT~US96/08390 best modes conLe~latéd for carrying out t_e ~llveLL~ioll. As will be re~li7Pri, the invention is capable of other different obvious aspects all without departing from the invention. Accordingly, the drawings and description will be regarded as illu~LLdLive in nature and not as restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
..
The accompanying drawings incorporated in and forming a part of the specification, illustrate several aspects of the present invention, and together with the description serve to explain t_e principles of the invention. In the drawings:
Fig.1 is a perspective view of a propellant tool for driving nails that is constructed according to the principles of the present invention;
Fig. 2 is an isometric view, partially in cross-section, of the main body of thepropellant tool of Fig. 1 depicting an internal cylinder within the body for reciprocally driving a driver and gas return cylinder for returning the driver to a predetermined position with tlle cross-sectional portion of the cylinder being taken along line 2-2 in Fig. 1;
Fig. 3 is an exploded view of ignition chamber of the propellant tool illustrated in Fig. 1 depicting the relationship between the various components of the ignition chamber and a strip of propellant charges;
Fig. 4 is a cross-sectional elevational view of the combustion chamber of Fig.
3 taken along line 4-4 in Fig. 2 and depicting a propellant charge colllplessingly engaged between two relatively movable components of the ignition chamber; and Fig. 5 is an exploded view of the driver stop mech~ni~m illustrated in Fig. 2.
W O 96~9283 , PCTrUS96/08390 Rt:r~lt~cc will now be made in detail to the present ~ r~llcd embodiment of the invention, an exarnple of which is illustrated in the ~cc~ lyiug drawings, wherein like numerals inllir~t~ the same elements throughout the views.
S DETAILED DESCRIPTION OF THE PREF'ERRED EMBODIMENT
Referring now to the drawings, Fig. 1 is a perspective view of a propellant tool, generally ~le~ ted by the numeral 10, that is constructed in accordance with theprinciples of the present invention. The illustrated propellant tool 10 incl~ ?s a main body 12 which supports a handle 14, a guide body 16 and a pistoniess gas spring return assembly 17. As illustrated, the guide body 16 supports a fastener m~g~7in~ 18 which, in turn, supports a plurality of fasteners, c:ollectively i~itontifierl by the numeral 20. The fasteners 20, which are specifir~lly shown in the drawing of Fig. 1 as nails, are feed into the guide body 16 where they are contacted by a driver (not shown in Fig. 1, see Fig. 2) and driven into a structure (not shown) to be fastened.
As shown in Fig. 1, the body 12 is partially covered by _ muffler 22 used to reduce noise from a combustion chamber (not shown in Fig. 1, see 4). A pair of carns 24,26 are rotatably disposed about the main body 12 to control movement of a chamber block 28 relative to the main body 12. The cams 24,26 each are pivotally mounted on trunions 30 (only one of which is shown in Fig. 1) ~tenrlinF ~uL~aldly from the main body 12. Each of the cams 24,26 also has an internal opening 32 defining a cam surface 34 for guiding movement of trunions 36 (only one of which is shown in Fig.
t~n~7insg outwardly from the chamber block 28. The cams 24,26 are hlL~rco~ected by a cam tie bar 38.
Fig. 2 shows the main body 12 with various of the outer components of the tool 10 removed. The main body 12 has an internal cylinder 40 in which a driver 42 ofgenerally cylindrical configuration is reciprocally movable. The driver 42 has a piston portion 42a at one axial end (the top end as illustrated in Fig. 2). The piston portion 42a is connected to a shank portion 42b by a frusco-conical seat portion 42c. The axial end of the shank portion 42b distal to the piston portion 42a extends into the guide body 16 and termin~tes in a driving end (not shown) that is used to contact and succe~iively drive the fa~ten~rs 20 into a structure (not shown) position~tl arlj~r~nt to the distal end of guide body 16, as is cullv~ irJn~l in the art. As those skilled in the art will readily ~l~pl~,ia~e, such driving action of the driver 42 is achieved by axial movement of the driver 42 within the cylinder 40. In tne ~l~rel,ed form of the invention, the driver 42 is reciprocally movable between a first retracted position, illustrated in Fig. 2, to an ~xtrn~ l position in which the driving end of the driver 42 extends out of the guide body 16. In this ~xt~n~-d position, the seat 42c of the driver 42 progressively engages a driver stop meçhani~m, generally i(lentifi~l by the drawing numeral 60. The stop merh~ni~m 60 is illustrated in greater detail in the drawing of Fig. 5.
The driver 42 is moved within the cylinder 40 from the retracted to the e~t~n~led positions under the impetus of pressure formed in a combustion chamber 44 (see Fig. 4) partially located between the chamber block 28 and the main body 12.
Pressure is selectively formed in the combustion chamber through the ignition of a caseless propellant charge 62. As depicted in Figs. 2-4, the caseless charge is introduced into the combustion chamber 44 through a propellant charge inlet passage 63. In the specifically illustrated embodiment, the caseless charge is transported through the inlet passage 63 on a strip 64 formed of paper, plastic or other ~L".l~,L,liate material. The propellant charge is ignited in the combustion chamber 44 by a reciprocally movable ignition member 66 in a manner disclosed in greater detail below.
The driver 42 is returned from the rxt~nrlrd to the retracted positions by the gas spring return assembly 17 to which the driver 42 is merh~ni~lly i"~ co~ ected. More specifically, a driver cap 48 extends radially outwardly from the piston portion 42a of driver 42 and through a slot 50 in the main body 12 to a gas spring rod 46 of the pistonless gas spring return assembly 17. The gas spring rod 46 has a cylindrical configuration (except for a minor taper in the portion disposed within the driver cap 48.
The axial end of the gas spring rod 46 opposite the hlL~l~,o"llection to the driver cap 48 extends into a closed ended housing 68 cnnt~ining a sealed cvlll~essi'L,le ffuid that is independent of and se~,lcg~ed from any ffuid in the internal cylinder 40 for the driver. When the propellant charge 62 is ignited in combustion 'chamber 44, the gas spring rod 46 is forced axially into the hnu~inF 68 by virtue of the m~ch~nir~l illLel~,u~ ctit n between the gas spring rod 46 and the driver 42. This movement of the gas spring rod into the housing 68 culll~ sses the sealed gaseous ffuid within housing 68. The pistonless gas spring return assembly 17 then is operative, whencombustion pl e~.ul e within the combustion chamber 44 is reduced! to return the driver 42 to its retracted position (as illustrated in Fig. 2) in response to the incre~sed pres~ul e of the sealed cuLu~re~.ible fluid in the gas spring cylinder created when the driver is moved to its extenn'ed position.
Referring jointly now to Figs. 3 and 4, the details of the combustion chamber 44 and the method in which the propellant charge 62 is ignited are shown in greater detail. The propellant charge 62 is advanced into the combustion chamber 44 on strip 64 where the charge 62 is positioned at a predetermined location by clamping the strip 64, thereby locating the propellant change 62 in a secure position between the chamber block 28 and the main body 12. The combustion chamber 44 is partially disposed in a recess 70 formed in the main body 12. The recess 70 is sized and configured toreceive and support an orifice plate 74 that is press fit into the recess 70. The orifice plate 74 has a plurality of orifices 76 (see Fig 4) that provide fluid cullllllullication between the combustion chamber 44 and the internal cylinder 40 ~see Fig. 2) for the driver 42. A pedestal 78 is integral with and centrally disposed upon the orifice plate 74. The pedestal 78 extends axially uuLw~dly therefrom toward the chamber block 28 into the combustion chamber 44. The chamber block 28 in~lnrlt-s axially adjustable chamber top 80 that defines the axial end of the combustion chamber 44 opposite the orifice plate 74. The chamber top 80 cooperates with the pedestal 78 to col~ ssiugly engage one of the propellant charges 62 therebetween; as more fully described below.
According to one aspect of the invention, an annular C-ring, preferably formed of a metallic material such as stainless steel or tir~nillm~ is interposed between the -)2 . CA 02222414 1997-11-26 W ~96~928~ PC~ f~ 90 chamber top 80 and the orifice plate 74 tn provide a se .~iing relatiorl be~ween the~e ~WQ
e,',~ment~ r~}}~r W~ h ~ t~m,- ~2~oC~, ~S a ~ "~ y C~'~e~ c~-sP~2nn~22 cu~ 2~ l, de~e a ~I."""'~,~r ~ r"~l;",J r~dially uu~wi~l beyond its axia~
ends. T~e C-ring is rr~iliently expandable under the inflnt-nee of combustion ples~,~e wit'r,in the cr2mh.~ctT~n ~ ;~,s m~ r~y ~~ 1 frQm r~ 4.
Such exF~andabiliy alIows the C-ring to retain sealing contact with hoth the ori~lce plate ~4 2nfl' t}le rh~ ,2~r to~ ~0 as tna~e tWQ elem,-r.t~ e~?e~ience rela~ve ~Yi~'l ~V~ment under the inflnrnre of combustion pressure. Consequently, the C-ring is operative to increase and enhance se31ing l.)lt:S~LI e between the orifice plate 74 and the ch~mber top 80 in response to combus~ion pressure cre:~ted in the combustion chamber upon ignilion of the propellant char~e 67. An e,Ytended bacl;ina ring 8~, also supported by the orifice plate 7~ is circJlllferenLially disposed about the C-ring 82 and functions to hold the ariîice plate 7d in place and e~rap the ~o As noled above. the orifice plate 7d has at least one, and in the plt:r~ d embodiment, a subs~.antial lumber (see Fi~. 3) of orifices 76 that provide fluidCu"lr,~ rOll ~, .w.~.~ ~e ~L~l.~J.i..~U~irL)ll Lil~)C~ ~4 an~ the cyliII~er ~. These orifices preferablv are sized to substantially restric~ nnignin~d solid components of the propellant charge 62 from entering the cylinder ~0. The propellant charses 62 of the ~0 preferred embodimen~ are formed of nitrocellulose fiber and the op~iional levels of solid component res~;ricIion throuch the orifIces 76 are dependent upon the avera~e length of the propellan~ charge fibers. It has been found tnat the orifices are optimally sized to have a diametral dimension of approximately one-third the average length of the propellent charge fibers. in the pLeî~.ed embodiment, the orifices 76 are sized with tli~mt~rt-r5 ra~gi~g from~010 ta .07'0 inc~esJto ~nrnm~ h th;s fTTn~t;on . ZS4~ '7 ~ ~ ~
The propellant charge 62 inrl~ a body 86 for ned of a first combustible material such as ni~rocellulose fibers. ln tne preferred embodiment, the fibers used to form the primary combustible material 86 have an average length of approximately~
inc~. rn accordance with another aspect of this inven~ion, the e,Y~ernal surface of the propellan~ charge body 86 is coa~ed with an oxidizer layer 88, which preferably is A~NDEO ~E~
W O 96~9283 PCTAUS96/08390 fonned of a mixture of a combustible material and an ~ r rich material. In the ed embo-limt~nf, the nxitii71or coating 88 is formed of a mixture of about 5% toabout 60 % potassium chlorate by weight and from about ~ % to about 80 % nitroce~ os by weight. The nitroc~llnlose used to form the coating 88 may be in the form of fibers, and if so, these fibers would plt;reldbly have an average length that is~,ubs~LuLially shorter than the average fiber length of the nitrocellulose forming the body 86. Even more p.er~lably, the coating is in the form of a cube or a sphere in order to improve coating properties.
As suggested from jointly viewing Figs. 3 and 4, the propellant strip 64 is formed of two layers of paper, plastic or other suitable material, a first layer 64a and a second layer 64b, with the propellant charge 62 being sandwiched between theselayers 64a and 64b. A sPnciti7er material 90 is deposited onto the outer surface of the layer 64b opposite the propellant charge 62. The sPnciri7er material 90, which is preferably red phosphorus con~ained in a binder, is located proximal to at least a portion of the oxidizer rich layer 88, but is separated from the n~ i7er rich layer 88 by the strip material layer 64b.
The propellant charge 62 is positioned in the combustion chamber 44 so as to place the sensitizer material 90 into the path of an ignition member 66, which ignition member 66 is reciprocally movable in a bore 92 extentling obliquely tarough the orifice plate 74. Movement of the ignition member 66, which movement is initi~tPd by depression of a trigger 94 (see Fig. 1) on the tool 10 in a m~nner well known in the art, causes an firing pin tip 96 on the end of the ignition member 66 to pierce and to be driven into the caseless propellant cha,ge 62. In addition to generating heat due to the friction bet~,veen the firing pin tip 96 and the sensitizer material 90, such action forces tae sensitizer material 90 to be im~rrni~Pd with the oxidizer coating 88. This interaction initiates decomposition of the oxidizer component within the oxidizer rich coating 88 and generates hot oxygen. In turn, this ignites the fuel component within the oxidizer rich coating 88 and subsequently tbe combustible material 86.
~ . CA 02222414 1997-11-26 _ W Q ~9Z83. PC~ TS~ 390 As is appare~t from the above descripuorlt tb~ firin~ pin tip 96 of the i~nirinnml~mhPr ~ strikes the ~rope~l~nr charge 6Z a~ a~ ah~ np angl~ ~i~ re~e~ ta the surfac~ of the c~ 62 ar~d a~r~es a slle~.~ force aa~nst t~e c~arge 62. l~e an~Eeof the i~nitinn member moveme~t also is obli~ue to the direcuorL of movement of the driYer 42. and the relaUYe~vt~ ~L hew~re~ t~ Tmh~-r hLQc~c and mairL b~dy l~
T~e ~edestal af c~e ~rir~ce plate 74 alco adv~nt~ cly incureS cnm~
combustion of che propellant charge 62 by directing ignicion gases throu~h the charge 62. As is observable from the depictions of Figs. 3 and 4, the pedestal 78 - 10 , o~ ressingly engages an armular surrace of the propellanc charge 62 and separates the area wi~hin that annular surface from those por~ions of the charge sur~ace that are located radially outwardly therefrom. This is achieved by an annular compressionridge 9~ that extends axially u.~wardly from the pedes~ 78 As ilLustrGted in Fig. 4, the f~ pirl tiE~ g~ of t~e i_~liti~E~ m~ml ~ 66 s~;es the proE~ellam c~arge 62 wi~
the area defined by the annular ridge 9~. The annular compression ridge 98, which is compressingly engage~ with the prop~ nt charge 62r is operative to restrict gas flow be~ween th~ surface of the charce witf~ the armuEar ridge g8 ancE those surraces af the charge 62 outside of the ridge 98. Thus, ignition gases formed by the ignilion of the charge 62 within the annular compression ridge 98 are directed radially uuLwd~dly through the charge 62. The clearance between the ignition member 66 and the bore92 are exaggerated in Fig. 4 for purposes of illustration. In practice the clearance is kept very close. as for example within~005 incy, to minimi7e flow of combustion gases through the bore 92. It also will bè see'7n that the bore 92 commnnic~t~s with a firing pin flush bore 100 that allows flushing of p~ially combusted propellallt charge r~ri ic fwm the bare ~2 ta pre~ t f~~ of the igr~itIon member 66 Turning finally to Fig. ~, a portion of the driver stop assembly 60 shown in Fig. 2 is illustrated in greater detail. In the specific form illustrated, the driver stop me~h~ni~m 60 includes a number of discrete components that are concentrically disposed about the shank portion 42b of driver 4~-~. including rwo stop pads 102 and W O 96/39283 PCTrUS96/08390 104, two resilient O-rings, 106 and 108, and tbree serially ~lign~ u~,ie.,sively sized and telescopically fitting metal cup shaped stop members 110, 112 and 114.
The stop member 110 has two conical contact surfaces, an interior contact surface l lOa, and an exterior contact surface l lOb. The stop member 110 is configured with contact~ r~ces llOa and llOb each forming an acute angle relative to the l-mgit ~ ,l axis 111 of the driver 42 and with the angle of contact surface l lOb being greater than that of contact surface 110a. Further, the surface area of contact surface 110b is greater than t'nat of contact surface llOa. The stop member 110 is con~ ntrically disposed about the driver 42 and pociti~n~-d "~ ent to the frusco-conical portion 42c so that the interior contact surface l lOa is contacted by the conical surface 42c of the driver when the driver 42 approaches the end of its driving stroke. The contact surface l lOa of the stop member is sized, configured and adapted to receive the conical surface of 42c the driver 42. As illustrated, the contact surface llOa has an in~ angle of ~pluxilllately 40 degrees, which angle is m~t~h~d to and ~plu~illlately the same as the conical surface 42c of the driver 42. The contact surface l lOa is generally symmetrically disposed about the Inngit~ l axes of the driver 42 and tool cylinder 40, which axes are represented by centerline 111 in Fig.~.
The stop member 112 is positioned to be contacted by stop member 110 and has a cup-shaped configuration that is similar to that of stop member 110. Like the stop member 110, the stop member 112 has an interior and exterior conical contact surfaces.
The interior contact surface is i~entifif~d by the numeral 112a and has an area o;~illlately equal to contact surface llOb. The exterior contact surface of stopmember 112 is designated by the numeral 112b and has a surface area that is greater tnan that of contact surface 112a. The interior contact 112a is adapted to receive the contact surface l lOb when the driver 42 approaches the end of its stroke, and accordingly has an angle ~yp~uxi~"ting that of contact surface 110b.
The stop member 114 also has two contact surfaces, an interior conical contact surface 114a and a planar contact surface 114b. The contact surface 114a is adapted W O 96/39283 PCT~US96/08390 to receive and has an angle ~ X;~ tinf~ that of contact surface 112b. The surface area of contact surface 114a is ~ (J~ ely the same as that of contact surface 112b.
The planar contact surface 114b, which cont~ t~ resilient stop pad 102, forms an angle of a~,ul.,xi,.,~t~ly 90 degrees with respect to the axis lil. The surface area of contact S surface 114b also is greater than that of contact surface 114a.
The driver stop assembly 60 filn~tinn~ to deaccelerate tbe driver 42 at the end of its driving stroke. As the driver 42 approaches its fully e~rt.on~ position, the tapered frusco-conical portion 42c of the driver 42 initially strikes and contacts the stop member 110. Due to the spacing provided by O-ring 106, the stop member 110 initially is isolated from the mass of stop members 112 and 114. After being impacted by the driver 42, the stop member 110 thereafter is moved axially with the driver 42 against the bias of the O-ring 106. After the resilient O-ring 106 is compressed, the contact surface l lOb of stop member 110 engages contact surface 112a of StOp member 112, which stop member 112 thereafter is moved axially to cu~ ess O-ring 108. Asthe stop member 112 is cont~ct~, it is moved axially against the bias of O-ring 108, causing contact surface 112b of stop member 112 to engage contact surface 114a of stop member 114. This action, in turn, drives the stop member 114 axially to compress the relatively soft resilient stop pad 102 and the relatively hard stop pad 104.
As seer in Fig. 2, the stop pad 104 is supported on a base plate 117 tbat is secured about its periphery to an axial end of the main body 12 by threaded f~tener 119 (only one of which is shown in Fig. 2). Any residual energy from the deacceleration of the driver 42 is absorbed by the base plate which flexes very slightly at its center portion, and by threaded fastener 119.
In accordance with one aspect of the driver stop assembly, ~ub~L~Lially all of the contact force between the driver 42 and stop member 110 is applied through the conical contact surfaces 42c and l lOa. Likewise, substantially all of the contact force between the stop members 110 and 112 is applied through the conical contact surfaces llOb and 112a. Similarly, substantially all of the contact force between the stop members 112 and 114 is applied through the conical contact surfaces 112b and 114a.
W O 96/39283 PCT~US96108390 By interfacing sllhst~nti~lly t~ ,ivc;ly at conical int~rf~re surfaces and focusing snhst~nti~lly all of the contact force between the metal stop members 110, 112 and 114 through these conical surfaces, energy is absorbed by the driver stop assembly without tne creation of a shear plane or other likely failure point.
According to anotber aspect of the driver stop assembly 60, the interface anglesbetween the various metal components increase progressively from the driver interface to the interface with the resilient pad lQ2. As schf~m~tir~lly depicted in Fig. ~, the interface angle A between the stop member 114 and the stop pad (aL)~ xi~ tf ly 90 degrees) (measured with respect to the axis 111) is greater than;the interface angle B
between the stop members 112 and 114. The angle B is greater tban the angle C
between the stop members 110 and 112, which is in turn greater tban the interface angle D (~ hllately 20 degrees) between the driver 42 and the stop member 110.
Thus, the interface angle through which the contact force is applied is progressively increased in the illustrated embodiment from ~ illlately a 20 degree interface angle between the driver 42 and the stop member 110 (approxim~tçly one half of the inrl~
angle of the contact surface 110a) to ~Lo.~illlately a 90 degree angle between the stop member 114 and the stop pad 102.
As also may be surmised from the drawings, the stop member 114 has a greater mass than stop 112, which in turn, has a greater mass than Stop 110. Thus, the effective mass of the driver 42 is increased gradually and non-linearly at an increasing rate to deaccelerated the driver 42. The stop mech~ni~m 60 causes tne driver to deaccelerate in several different ways. In ~ iitinn to the rl~ cçleration caused by the progressively increased effective mass of driver 42 created by the stop members 110, 112, and 114, the O-rings 106 and 108, dissipate energy from the driver 42 during co,ll~les~ion. The O-rings also function to provide a preflPt~rmined spacing between the stop members 110, 112 and 114 prior to contact by the driver 42. This effectively isolates the masses of the stop members 110, 112 and 114 with the result that the dynamics of the u~lle~ull stop members are substantially unaffected by the downstream members upon initial impact. The geometries of the driver portion 42c and the stop members cause each of the stop members 110, 112 and 114 to undergo hoop stress, further dissipating energy from the driver 42. Any residual energy from the driver is ~liccir,.t~otl by the cylinder base plate 12a (see Fig. 2), which cylinder base plate is secured to the cylinder by a bolt 117. In ~ itinn to tneir energy absorbing - 5 characteristics, the resilient characteristics of the O-rings 106 and 108 provide a predPtt-~nine-l space between the stop members 110, 112 and 114, causing these stop members to be sc~Led when the O-rings 106 and 108 are unco~ c:,sed. Hence, while the dynamic interrel,.tinnchip of the various components becomes somewhat complex at high impact speeds, the illustrated stop assembly 60 generally is designed so that as the effective operative inertial mass of the stop assembly applied to the driver 42 is increased, the speed of the driver 42 is reduced, and the contact surface area between the metal components and the interface angle of the impact are increasedprogressively.
The foregoing description of a pl~ft:lled embodiment of the invention has been presented for purposes of illustratiGn and description. It is not inten-led to be exhaustive or limit the invention to the precise form disclosed, and many motlifie ~fi~ nc and variations are possible in light of the above f~rhin~ The embodiment was chosen and described in order to best explain tne principles of t_e invention and its practical application to thereby enable ot_ers skilled in the art to best utilize the invention and various embodiments and with various modifications as are suited to the particular use con~,emplated. It is int~n-led tnat tr.e scope of the invention be defined by the claims appended hereto.
APPARATUS FOR rG~G A PROPE~ANT CHA~E IN A TdO~
T~C~CAL FIELI:2 The preser~ i~ve~h~rL i~ d~rected ~n~r~lly to dnvi~ taQl~ a~ mare particularly, to propellant dnv~ng tools of the type which use prqpellant charges to drive a f~ n~ or ot~ c~ect. The iIIventiar~ wilL ~e sE~ec~caLly di~ciased co~nectiorI w~th a driv~rrg taal that ig~ites a c seless propelIant charge artd uses the resultiIlg combustion gases to drive a nail.
BACKGROU~D OF THE I~VEi'1TIO~
The majorily of the fastener drivin~J tools in use today are pneumalically powered. I',-~."~ t~Qls u~ saurce af ~.~uLL~cd ~ tha~ is sttrt~iie~ t~ the t~l through ~ hose. l~is is a severe limit~ri~n on the versatilily of pnel-m~tic tools;
they must be tied to a saurce of air pres$ure by a hose, limitinG the distance which 1~ the tQols r~n be moved fram the air sourc-. In ~*~itinn, s~rne rem~te Jo~ sit~s make ir difficult to provide an easily accessible and economical air source. Theadded e~pense of providin~ electrical service to power the air source, or usin~
alternative power sources (such as ~Jasoline powered compressors) for providin~ the compressed air, subtract from the efficiency and convenience that pneumatic tools '70 traditionaLly provide. Therefore, there have becen many altempts to provide alternarives to pnellm~tic~lly acm~ d tools that can be used in sit~l~ti~n~ where the ;c ~s ~e ~ot ~ Y~r~
Q~e ~It.~ .y~ t~ e~e~ap~ ic a ~al w~c~ e~ .y ta provide the power needed to drive fasteners of the type and size that traditionally pneumatic tools drive. Most of these tools use an electric motor to power one ormore flvwhe_ls which, in turn, store suff~cient ener~y to drive the fasreners.
E~arnples of these tools are set forrh in U.S. Patent Nos. 4,04~,036; 4,1~1,745;
OEQ ~E~
- WQ ~61~9~ PC~l:.'US96/')~3''9Q
4,204,6Z2; 4,298,072; 4,32~ 7; and 4,~4,5i~. Hawever, t~ese taols st~ll suffer from the same timit~ti~lll as the pn~lm~tic tools in tha~ they must be cnnn~cte~ by a cor~ tQ an energy 5Q~C~
A secand ~it~ ;y;~ which has ref ~:ntLy beerL d~velaped i~ a e9mpl~t~1y 5elf-cnnt~ined fastener driving tool which is powered by internal combustion of a ~c.~ c fuel-air mixalre. E,~mples of these tools are fallnd i~ U S Pa~t Nas.
Z,898,8g3; 3~,042,(~05; ~,7I~,608; 3,gS0,359; 4,075,850; 4,zoo,zr,; 4,ZIg,g8g;
4,403,7'7'7; 4,415,110; and 4,7~,91~. While these tools need no connection to ane~temal power source and are e~remely versatile, they tend to be somewhat large,comple~, heavy and awlcward to use. In addition, they c n be less economical to operate in that the fuel used is relatively e~pensive.
Anatiter ciass ~}f tco~ is ~ y used ~c a~ t~
I~ pneumatic tools is the powder or propellant actuated tOOl. Powder or propellant act~-~ted fastener driving tools are used most fre~uently for driving fasteners into hard sl~nc~Pc 5uch a~ cc~cre~e The mcs~ comn~tn types ~ s~ch tools are tradi~ionally sin~le fastener, sin~le shot devices; that is, a sin~le fasteners is m~nl-~lly inserted into the barrel of the tool, alon~ with a sin~le propellant char~e.
After the fastener is dischar ed, the tool must be m~n~ 1y reloaded with both a fastener and a propellant char~e in order to be operated a~Jain. E:~arnples of such tools are described in U.S. Patent Nos. 4,830,254; 4,598,851; and 4,577,793.
Tn nro~lT~nt a~c~ t~d tccls, thar9 1~0--~y dif~rent type Or c~ gec ~ed fcr Fropall~+~. Fcr ~ n~ , '~r.S. ~ L ~0. 3,37'~,6A. +~clQ~la 1 lC~r CXF10~ c 2r;~ e fL '~ ,f L ..,',, .. ~.ry ,~ ~&~ t~S~95 n igniter pc.~ion nd hQving Q ~cb thicl~ncss lcs., th~n QQy other dirne~ion cf the pellct. I,r.S. I'Qtcnt ~rO. 3,5~J,518 i~, dirc_tcd to ~ po~dcr crLr~idg9 consisting ~f ~ r~Ticige c~se ccrstrl~c~ of t~o scp~tc piecs~ which cont ir ~ c~"+~l F~i3~er ~acei~ charnber ~ld fr. ~nr~ rroFoll;~t recei~ing ch~rnbsr. U.S. P~t~+ Nro 'NDED SfIEET
U.S. ~a~r~t Na. 3~,g7~ is c~ir~ctec~t~ a r~ r ~ri~ng tao~ USTrrg caseless propellant char~es which has a body, said body defining a 5 combustiorl chamber, anct a cylinder in fluid communication with the combustion chamber, the combustion chamber being at least partially formed by a flrst mern~er and a sec~nd rnember th~ ~re m~vable relative tQ
eact~ ottler.
0 In propellant ~ctl l~ted tcQls, there are many different types of cartrid~es used fcr pr~pellar~s. ~r exarnpLe, ~I.S. Patent Na. 3, 3~2,64:~
teaches a low explosive primerless charge consisting of a substantially resilient fibrous nitrocellulose pellet with an igniter portion and having a webthickness less than any other dimension of the pellet. U.S. Patent No.
- 15 3,529,548 is directed to a powder cartridge consisting of a cartridge case constructed of two separate pieces which contains a central primer receiving chamber and an annular propellant receiving chamber. U.S. Patent No.
3,911,825 discloses a propellant charge having an H-shaped cross section composed of a primer igniter charge surrounded by an annular propellant powder charge. EP560~83A is directed to a caseless pr~pettant charge for use in a fastener dri~fin~ toot, where the tc~l c~mpr;ses a bcdy defin;ng a ccmbustiort chamber ~nd fluid ct[amher, me~Ens f~r pasitioning a caseless propellant charge at a predetermined location in the combustion chamber, and an ignition member mounted within the body, with the ignition member being operative tQ stril~e the propellant charge and to apply a shearing force a~ainst the ~urface cf a propeliant charge when the prcpellant char~e is in the predetermined position.
AMENDED SHEET
; CA 02222414 1997-11-26 ~ W O 9~9283 PC~r~Sn~/f~J
3',~II,8't5 di_clo~~ n propcllcnt ch~rgc hnvin nn ~ hap~d _rocc c~tiorl c~~o~ed of ~ r~ c~ c~ 8 ~d~d by ~n n~ulnr pr~Qll~nt ;~
A second type of powder ~ tt~l taol EIaS 3~so beerL use~ in rece~t times.
'; Ihi~ tcQl etill use~ f~ctf~Tt~s which are irLdivid~ y l~a~ed i~ t~e fIr~'r chamize~
of the device. However, the propellant charges used to provide the energy neededta driYe the f~ct~ or~ ~re ~ravi~P~ a ~ a fl~Yi~1e bar~ af serially ~rr~;nQ~ ;rtn~ ~5 which are fed one-by-ane into the combustion charnber of the tool E,Yamples of this type of tool are taught in U.S. Parent 4,687,1'~6; 4,655,380; and 4,804,1'77 ID
the tools heretofore mentioned, which use a cartridge strip assembly, there are a variety of strips which are available for use. U.S Patent 3,611,870 is directed to a plastic strip in which a series of e~plosive char~Jes are located in recesses in the strip with a press fit ~r S Palent ~a. ~,~5,ISi teaches a cartrid~ stn-p far use with a ~uw~er a~TT~r~* t~al which is ~da~le ~to 2 rall a~aut an a~2s wh~c~ is substantially parallel to the surface portion of the strip and having the propellant cartridges disposed substantially perpendicular to the surface portion. U.S. Pate2t No. ~,675,154 te2che~i a fie~Ee L~ ~;~a~ s~p ~th ~ ec~aes forEIoldir~ rope~a~rt charges, wherein the thickness of the strip corresponds to the length of the charge contained therein. U.S. Patent No. 4,056,062 discloses a strip for carrying a caseless charge wherein the charge is held in the space bv a recess and a tower-shaped wall and is disposed in surface contact with the annular surface within 'the cartridge recess. U.S. Patent No. 4,819,562 describes a propellant cont~in;ng device whichhas a plurality of hollow members closed at one end arld a pluralit,v of closuremeans each having a peripheral rirn which fits into the open end of tne hollow ~75 membess af the device Recently, several powder artll~ted tools have been developed which operate in a manner sirnilar to the traditional pnellm~t;c tools; that is, these devices contain a m~g~7;ne which automaticallv feeds a pluralitv of fasteners serially to the drive D S~EET
W O 96~9283 PCT~US96/08390 charnber of the tool, while a strip of propellant charges is supplied serially to the tool to drive the fasteners.
One example of such a tool is described in U.S. Patent No. 4,821,938. This S patent, which teaches an .~llpl~vt:d version of a tool taught in U.S. Patent No.
4,655,380, is directed to a powder actl-~ted tool with an improved safety interlock which permits a cartridge to be fired only when a safety rod is forced into the barrel and cylinder assembly and when the barrel and cylinder assembly has been forced realw~Ldly into its ~ alw~-l position.
Another exarnple of this type of tool is taught in U.S. Patent No. 4,858,811.
This tool, which is an improved version of the tool taught in U.S. Patent No.
4,687,126, incorporates a handle, a tubular chamber, a piston, and a combustion chamber within the tubular chamber, the combustion chamber receiving a cartridge1~ in preparation for firing, which upon ignition, propels the piston fon,vardly for the driving of a nail. A fastener housing is located forwardly of the tubular chamber, and is provided for directing a strip of fasteners held by a m~7ine upwardly through the tool during repeated tool usage.
Both of the aforementioned recent powder actuated tools, however, are designed to drive fasteners into hard surfaces such as concrete. Consequently, aneed exists for a propellant acnl~ted tool that can be efficiently used as a replacement for traditional pnellm~tic tools which drive fasteners into wood.
It is thus an object of the present invention to ovt:lco-,le the disadvantages of the prior art by providing a propellant ~ct~l~t~d fastener driving tool which is lighter, less complex, and very similar to the traditional pneumatic tool.
- W O 96/39283 PC~,~S~~6/333 It is also an obJect ~f the present invention to provide a tool which c~n be e~~~ily and ~ffCi~ntly used in those wor~~ enviror~mt~ntr; wlle-e rfnpnmAt7~c tGals tr~ Ti*~n~7Tly use It is further a~ Q~e~:t of the pre~e~t inven ar~ ta prGVi~e a s~f~n~t,~in~
fastener driving tool which is safer a~ad less e~pensive to operate than tools currently available and k~aown in the ~
Additional objects, advantacres~ and other novel features of the invention will be set forth in par~ in the description that follows and in parl will become apparent to those skiIled in the arl upon e~Aminrtion of the following orma,v be le~rned with the practice of the invention. The objects and advanta ~es of the invention may be re;llized and ~tt~ b~, me:~ of the iIls~lmpnt~lit;ec ~d rlr~ s~cuiarly E~ir~te~ aut irI ttre ~ cI EmC
Summarv of the Invention To achieve the foregoincr and other objects, and in accordance with the purposesof the present invention disclosed herein, a propellant tool for driving~~n ~t is provided. The tool incllldes a body, a combuslion chamber within the body, means for introducing a caseless propellant char~e into the combustion chamber and for igniting ~ a- f R!~t~
the propellam charge and a cylinder for driving ,~n ~bi~t . An oririce plate is interposed be~ween the combustion chamber and the cylinder. The oririce plale conta7ns a plurality of orifices~for pravidincr fluId commllnication be7ween thecnmhETct;nn chamber and the cyLinder. The orifice-~~ are sized ta ~ Alll;, TTy res~c~
7lnic~nitl~i saI~i ~,u~ ~ ~ the pr~e~anE c~rge from ~ a ~e ~_yl~
orifices preferably have a diameter ~,plo,~,l,ately one-third the length of the average length of the propellant fibers forming the propellant.
AM~ND~3 ~EET
- W O 9~ 83 PE~,~'S9 ~ ~,t~
In another aspect of the invention, a propellant tool for drivmg ~" obj~c~
irlrlllflf~ a 7~dy fif~fi~t;na a ~L~ a f~ f h~m7lf~r ~ ifi f~~ lie~l..)ll w~tk t~e cLJIl~ c~,.m7Jer, me~s for pn~r~;r~ a case~ess propellant charge at a pre~7~tf~tTninf~fl location in the combustion ch~mher an~ a~
i~nirinn member ~ ~t~ the bady ta ~e t~e p.-ope~ t cha~,e at a l obL~e angle and to apply a shearing force against the surface of a propellant charge when the prq;lf 71~nt c harg~ is ir~ tke pre~er-f rTninf~d pQ~i~iQr~ e ianir;on memher pr~:fc.~ly i~
reciprocally movable within the body and operative to pierce the surface of the caseless charge. The caseless propellant charge preferably is forrned of a combustible material, an n~ifli7~r material, and a sPn~iti7~r materi 1, and the piercing of the c~seless charge is operative to mix the combustible, o~idizer and sensitizer materials.
~ r ln accordance with still a~other as7?ect of the invention, a propellant tool for - drivin_ ~n r~ ~r i~r7t~f~toS a E~Qf1Y ~ a t~ U~L ~L~e. irr t~e 7~ad~ for ~,C~
an ignitable propellant charge. The combustion chamber is formed by at least tworelatively movable components that zre operative to receive and compressingly engage - a p~ell~t char~ ~i~ se~i there~e~wee~ e ~ ~e rela~ively m~al~ie Cul~lp~
has an annular compression surface for conr~rr;nc an annular surface area of a propellant charge engaged by the relatively movable components. The armular compression surface separa~es a selected surface area of the propellan~ charge withIn the compression rin~ from the ra~ially ou~ward portions of ~e propellant charge surface. The ~nnular compression surface is operative to restrict gas flow between the selected surface area of the engaged propellant charge from the radially outwardportions of the propellarlt charge surface. An igrlition member contacts the selected surface of the propellant char_e ~ i~tes t~e se~ected area ~ this way, i~n;r;nn gases f~e~ by i"~t'IC~ ~f t}~ Esrg~ c~arge ir~ the SP~ area are fQrre~
through the r~m~;n~r of the charge.
Still other objects of the present invention will become apparent to those s~illed in this art from the following descrip~ion wherein there is shown and described a preferred embodimen~ of this inventiorl, simply by way of illustration, of one of the ~MEI\ID~D S¢fEEr W O 96~9283 PCT~US96/08390 best modes conLe~latéd for carrying out t_e ~llveLL~ioll. As will be re~li7Pri, the invention is capable of other different obvious aspects all without departing from the invention. Accordingly, the drawings and description will be regarded as illu~LLdLive in nature and not as restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
..
The accompanying drawings incorporated in and forming a part of the specification, illustrate several aspects of the present invention, and together with the description serve to explain t_e principles of the invention. In the drawings:
Fig.1 is a perspective view of a propellant tool for driving nails that is constructed according to the principles of the present invention;
Fig. 2 is an isometric view, partially in cross-section, of the main body of thepropellant tool of Fig. 1 depicting an internal cylinder within the body for reciprocally driving a driver and gas return cylinder for returning the driver to a predetermined position with tlle cross-sectional portion of the cylinder being taken along line 2-2 in Fig. 1;
Fig. 3 is an exploded view of ignition chamber of the propellant tool illustrated in Fig. 1 depicting the relationship between the various components of the ignition chamber and a strip of propellant charges;
Fig. 4 is a cross-sectional elevational view of the combustion chamber of Fig.
3 taken along line 4-4 in Fig. 2 and depicting a propellant charge colllplessingly engaged between two relatively movable components of the ignition chamber; and Fig. 5 is an exploded view of the driver stop mech~ni~m illustrated in Fig. 2.
W O 96~9283 , PCTrUS96/08390 Rt:r~lt~cc will now be made in detail to the present ~ r~llcd embodiment of the invention, an exarnple of which is illustrated in the ~cc~ lyiug drawings, wherein like numerals inllir~t~ the same elements throughout the views.
S DETAILED DESCRIPTION OF THE PREF'ERRED EMBODIMENT
Referring now to the drawings, Fig. 1 is a perspective view of a propellant tool, generally ~le~ ted by the numeral 10, that is constructed in accordance with theprinciples of the present invention. The illustrated propellant tool 10 incl~ ?s a main body 12 which supports a handle 14, a guide body 16 and a pistoniess gas spring return assembly 17. As illustrated, the guide body 16 supports a fastener m~g~7in~ 18 which, in turn, supports a plurality of fasteners, c:ollectively i~itontifierl by the numeral 20. The fasteners 20, which are specifir~lly shown in the drawing of Fig. 1 as nails, are feed into the guide body 16 where they are contacted by a driver (not shown in Fig. 1, see Fig. 2) and driven into a structure (not shown) to be fastened.
As shown in Fig. 1, the body 12 is partially covered by _ muffler 22 used to reduce noise from a combustion chamber (not shown in Fig. 1, see 4). A pair of carns 24,26 are rotatably disposed about the main body 12 to control movement of a chamber block 28 relative to the main body 12. The cams 24,26 each are pivotally mounted on trunions 30 (only one of which is shown in Fig. 1) ~tenrlinF ~uL~aldly from the main body 12. Each of the cams 24,26 also has an internal opening 32 defining a cam surface 34 for guiding movement of trunions 36 (only one of which is shown in Fig.
t~n~7insg outwardly from the chamber block 28. The cams 24,26 are hlL~rco~ected by a cam tie bar 38.
Fig. 2 shows the main body 12 with various of the outer components of the tool 10 removed. The main body 12 has an internal cylinder 40 in which a driver 42 ofgenerally cylindrical configuration is reciprocally movable. The driver 42 has a piston portion 42a at one axial end (the top end as illustrated in Fig. 2). The piston portion 42a is connected to a shank portion 42b by a frusco-conical seat portion 42c. The axial end of the shank portion 42b distal to the piston portion 42a extends into the guide body 16 and termin~tes in a driving end (not shown) that is used to contact and succe~iively drive the fa~ten~rs 20 into a structure (not shown) position~tl arlj~r~nt to the distal end of guide body 16, as is cullv~ irJn~l in the art. As those skilled in the art will readily ~l~pl~,ia~e, such driving action of the driver 42 is achieved by axial movement of the driver 42 within the cylinder 40. In tne ~l~rel,ed form of the invention, the driver 42 is reciprocally movable between a first retracted position, illustrated in Fig. 2, to an ~xtrn~ l position in which the driving end of the driver 42 extends out of the guide body 16. In this ~xt~n~-d position, the seat 42c of the driver 42 progressively engages a driver stop meçhani~m, generally i(lentifi~l by the drawing numeral 60. The stop merh~ni~m 60 is illustrated in greater detail in the drawing of Fig. 5.
The driver 42 is moved within the cylinder 40 from the retracted to the e~t~n~led positions under the impetus of pressure formed in a combustion chamber 44 (see Fig. 4) partially located between the chamber block 28 and the main body 12.
Pressure is selectively formed in the combustion chamber through the ignition of a caseless propellant charge 62. As depicted in Figs. 2-4, the caseless charge is introduced into the combustion chamber 44 through a propellant charge inlet passage 63. In the specifically illustrated embodiment, the caseless charge is transported through the inlet passage 63 on a strip 64 formed of paper, plastic or other ~L".l~,L,liate material. The propellant charge is ignited in the combustion chamber 44 by a reciprocally movable ignition member 66 in a manner disclosed in greater detail below.
The driver 42 is returned from the rxt~nrlrd to the retracted positions by the gas spring return assembly 17 to which the driver 42 is merh~ni~lly i"~ co~ ected. More specifically, a driver cap 48 extends radially outwardly from the piston portion 42a of driver 42 and through a slot 50 in the main body 12 to a gas spring rod 46 of the pistonless gas spring return assembly 17. The gas spring rod 46 has a cylindrical configuration (except for a minor taper in the portion disposed within the driver cap 48.
The axial end of the gas spring rod 46 opposite the hlL~l~,o"llection to the driver cap 48 extends into a closed ended housing 68 cnnt~ining a sealed cvlll~essi'L,le ffuid that is independent of and se~,lcg~ed from any ffuid in the internal cylinder 40 for the driver. When the propellant charge 62 is ignited in combustion 'chamber 44, the gas spring rod 46 is forced axially into the hnu~inF 68 by virtue of the m~ch~nir~l illLel~,u~ ctit n between the gas spring rod 46 and the driver 42. This movement of the gas spring rod into the housing 68 culll~ sses the sealed gaseous ffuid within housing 68. The pistonless gas spring return assembly 17 then is operative, whencombustion pl e~.ul e within the combustion chamber 44 is reduced! to return the driver 42 to its retracted position (as illustrated in Fig. 2) in response to the incre~sed pres~ul e of the sealed cuLu~re~.ible fluid in the gas spring cylinder created when the driver is moved to its extenn'ed position.
Referring jointly now to Figs. 3 and 4, the details of the combustion chamber 44 and the method in which the propellant charge 62 is ignited are shown in greater detail. The propellant charge 62 is advanced into the combustion chamber 44 on strip 64 where the charge 62 is positioned at a predetermined location by clamping the strip 64, thereby locating the propellant change 62 in a secure position between the chamber block 28 and the main body 12. The combustion chamber 44 is partially disposed in a recess 70 formed in the main body 12. The recess 70 is sized and configured toreceive and support an orifice plate 74 that is press fit into the recess 70. The orifice plate 74 has a plurality of orifices 76 (see Fig 4) that provide fluid cullllllullication between the combustion chamber 44 and the internal cylinder 40 ~see Fig. 2) for the driver 42. A pedestal 78 is integral with and centrally disposed upon the orifice plate 74. The pedestal 78 extends axially uuLw~dly therefrom toward the chamber block 28 into the combustion chamber 44. The chamber block 28 in~lnrlt-s axially adjustable chamber top 80 that defines the axial end of the combustion chamber 44 opposite the orifice plate 74. The chamber top 80 cooperates with the pedestal 78 to col~ ssiugly engage one of the propellant charges 62 therebetween; as more fully described below.
According to one aspect of the invention, an annular C-ring, preferably formed of a metallic material such as stainless steel or tir~nillm~ is interposed between the -)2 . CA 02222414 1997-11-26 W ~96~928~ PC~ f~ 90 chamber top 80 and the orifice plate 74 tn provide a se .~iing relatiorl be~ween the~e ~WQ
e,',~ment~ r~}}~r W~ h ~ t~m,- ~2~oC~, ~S a ~ "~ y C~'~e~ c~-sP~2nn~22 cu~ 2~ l, de~e a ~I."""'~,~r ~ r"~l;",J r~dially uu~wi~l beyond its axia~
ends. T~e C-ring is rr~iliently expandable under the inflnt-nee of combustion ples~,~e wit'r,in the cr2mh.~ctT~n ~ ;~,s m~ r~y ~~ 1 frQm r~ 4.
Such exF~andabiliy alIows the C-ring to retain sealing contact with hoth the ori~lce plate ~4 2nfl' t}le rh~ ,2~r to~ ~0 as tna~e tWQ elem,-r.t~ e~?e~ience rela~ve ~Yi~'l ~V~ment under the inflnrnre of combustion pressure. Consequently, the C-ring is operative to increase and enhance se31ing l.)lt:S~LI e between the orifice plate 74 and the ch~mber top 80 in response to combus~ion pressure cre:~ted in the combustion chamber upon ignilion of the propellant char~e 67. An e,Ytended bacl;ina ring 8~, also supported by the orifice plate 7~ is circJlllferenLially disposed about the C-ring 82 and functions to hold the ariîice plate 7d in place and e~rap the ~o As noled above. the orifice plate 7d has at least one, and in the plt:r~ d embodiment, a subs~.antial lumber (see Fi~. 3) of orifices 76 that provide fluidCu"lr,~ rOll ~, .w.~.~ ~e ~L~l.~J.i..~U~irL)ll Lil~)C~ ~4 an~ the cyliII~er ~. These orifices preferablv are sized to substantially restric~ nnignin~d solid components of the propellant charge 62 from entering the cylinder ~0. The propellant charses 62 of the ~0 preferred embodimen~ are formed of nitrocellulose fiber and the op~iional levels of solid component res~;ricIion throuch the orifIces 76 are dependent upon the avera~e length of the propellan~ charge fibers. It has been found tnat the orifices are optimally sized to have a diametral dimension of approximately one-third the average length of the propellent charge fibers. in the pLeî~.ed embodiment, the orifices 76 are sized with tli~mt~rt-r5 ra~gi~g from~010 ta .07'0 inc~esJto ~nrnm~ h th;s fTTn~t;on . ZS4~ '7 ~ ~ ~
The propellant charge 62 inrl~ a body 86 for ned of a first combustible material such as ni~rocellulose fibers. ln tne preferred embodiment, the fibers used to form the primary combustible material 86 have an average length of approximately~
inc~. rn accordance with another aspect of this inven~ion, the e,Y~ernal surface of the propellan~ charge body 86 is coa~ed with an oxidizer layer 88, which preferably is A~NDEO ~E~
W O 96~9283 PCTAUS96/08390 fonned of a mixture of a combustible material and an ~ r rich material. In the ed embo-limt~nf, the nxitii71or coating 88 is formed of a mixture of about 5% toabout 60 % potassium chlorate by weight and from about ~ % to about 80 % nitroce~ os by weight. The nitroc~llnlose used to form the coating 88 may be in the form of fibers, and if so, these fibers would plt;reldbly have an average length that is~,ubs~LuLially shorter than the average fiber length of the nitrocellulose forming the body 86. Even more p.er~lably, the coating is in the form of a cube or a sphere in order to improve coating properties.
As suggested from jointly viewing Figs. 3 and 4, the propellant strip 64 is formed of two layers of paper, plastic or other suitable material, a first layer 64a and a second layer 64b, with the propellant charge 62 being sandwiched between theselayers 64a and 64b. A sPnciti7er material 90 is deposited onto the outer surface of the layer 64b opposite the propellant charge 62. The sPnciri7er material 90, which is preferably red phosphorus con~ained in a binder, is located proximal to at least a portion of the oxidizer rich layer 88, but is separated from the n~ i7er rich layer 88 by the strip material layer 64b.
The propellant charge 62 is positioned in the combustion chamber 44 so as to place the sensitizer material 90 into the path of an ignition member 66, which ignition member 66 is reciprocally movable in a bore 92 extentling obliquely tarough the orifice plate 74. Movement of the ignition member 66, which movement is initi~tPd by depression of a trigger 94 (see Fig. 1) on the tool 10 in a m~nner well known in the art, causes an firing pin tip 96 on the end of the ignition member 66 to pierce and to be driven into the caseless propellant cha,ge 62. In addition to generating heat due to the friction bet~,veen the firing pin tip 96 and the sensitizer material 90, such action forces tae sensitizer material 90 to be im~rrni~Pd with the oxidizer coating 88. This interaction initiates decomposition of the oxidizer component within the oxidizer rich coating 88 and generates hot oxygen. In turn, this ignites the fuel component within the oxidizer rich coating 88 and subsequently tbe combustible material 86.
~ . CA 02222414 1997-11-26 _ W Q ~9Z83. PC~ TS~ 390 As is appare~t from the above descripuorlt tb~ firin~ pin tip 96 of the i~nirinnml~mhPr ~ strikes the ~rope~l~nr charge 6Z a~ a~ ah~ np angl~ ~i~ re~e~ ta the surfac~ of the c~ 62 ar~d a~r~es a slle~.~ force aa~nst t~e c~arge 62. l~e an~Eeof the i~nitinn member moveme~t also is obli~ue to the direcuorL of movement of the driYer 42. and the relaUYe~vt~ ~L hew~re~ t~ Tmh~-r hLQc~c and mairL b~dy l~
T~e ~edestal af c~e ~rir~ce plate 74 alco adv~nt~ cly incureS cnm~
combustion of che propellant charge 62 by directing ignicion gases throu~h the charge 62. As is observable from the depictions of Figs. 3 and 4, the pedestal 78 - 10 , o~ ressingly engages an armular surrace of the propellanc charge 62 and separates the area wi~hin that annular surface from those por~ions of the charge sur~ace that are located radially outwardly therefrom. This is achieved by an annular compressionridge 9~ that extends axially u.~wardly from the pedes~ 78 As ilLustrGted in Fig. 4, the f~ pirl tiE~ g~ of t~e i_~liti~E~ m~ml ~ 66 s~;es the proE~ellam c~arge 62 wi~
the area defined by the annular ridge 9~. The annular compression ridge 98, which is compressingly engage~ with the prop~ nt charge 62r is operative to restrict gas flow be~ween th~ surface of the charce witf~ the armuEar ridge g8 ancE those surraces af the charge 62 outside of the ridge 98. Thus, ignition gases formed by the ignilion of the charge 62 within the annular compression ridge 98 are directed radially uuLwd~dly through the charge 62. The clearance between the ignition member 66 and the bore92 are exaggerated in Fig. 4 for purposes of illustration. In practice the clearance is kept very close. as for example within~005 incy, to minimi7e flow of combustion gases through the bore 92. It also will bè see'7n that the bore 92 commnnic~t~s with a firing pin flush bore 100 that allows flushing of p~ially combusted propellallt charge r~ri ic fwm the bare ~2 ta pre~ t f~~ of the igr~itIon member 66 Turning finally to Fig. ~, a portion of the driver stop assembly 60 shown in Fig. 2 is illustrated in greater detail. In the specific form illustrated, the driver stop me~h~ni~m 60 includes a number of discrete components that are concentrically disposed about the shank portion 42b of driver 4~-~. including rwo stop pads 102 and W O 96/39283 PCTrUS96/08390 104, two resilient O-rings, 106 and 108, and tbree serially ~lign~ u~,ie.,sively sized and telescopically fitting metal cup shaped stop members 110, 112 and 114.
The stop member 110 has two conical contact surfaces, an interior contact surface l lOa, and an exterior contact surface l lOb. The stop member 110 is configured with contact~ r~ces llOa and llOb each forming an acute angle relative to the l-mgit ~ ,l axis 111 of the driver 42 and with the angle of contact surface l lOb being greater than that of contact surface 110a. Further, the surface area of contact surface 110b is greater than t'nat of contact surface llOa. The stop member 110 is con~ ntrically disposed about the driver 42 and pociti~n~-d "~ ent to the frusco-conical portion 42c so that the interior contact surface l lOa is contacted by the conical surface 42c of the driver when the driver 42 approaches the end of its driving stroke. The contact surface l lOa of the stop member is sized, configured and adapted to receive the conical surface of 42c the driver 42. As illustrated, the contact surface llOa has an in~ angle of ~pluxilllately 40 degrees, which angle is m~t~h~d to and ~plu~illlately the same as the conical surface 42c of the driver 42. The contact surface l lOa is generally symmetrically disposed about the Inngit~ l axes of the driver 42 and tool cylinder 40, which axes are represented by centerline 111 in Fig.~.
The stop member 112 is positioned to be contacted by stop member 110 and has a cup-shaped configuration that is similar to that of stop member 110. Like the stop member 110, the stop member 112 has an interior and exterior conical contact surfaces.
The interior contact surface is i~entifif~d by the numeral 112a and has an area o;~illlately equal to contact surface llOb. The exterior contact surface of stopmember 112 is designated by the numeral 112b and has a surface area that is greater tnan that of contact surface 112a. The interior contact 112a is adapted to receive the contact surface l lOb when the driver 42 approaches the end of its stroke, and accordingly has an angle ~yp~uxi~"ting that of contact surface 110b.
The stop member 114 also has two contact surfaces, an interior conical contact surface 114a and a planar contact surface 114b. The contact surface 114a is adapted W O 96/39283 PCT~US96/08390 to receive and has an angle ~ X;~ tinf~ that of contact surface 112b. The surface area of contact surface 114a is ~ (J~ ely the same as that of contact surface 112b.
The planar contact surface 114b, which cont~ t~ resilient stop pad 102, forms an angle of a~,ul.,xi,.,~t~ly 90 degrees with respect to the axis lil. The surface area of contact S surface 114b also is greater than that of contact surface 114a.
The driver stop assembly 60 filn~tinn~ to deaccelerate tbe driver 42 at the end of its driving stroke. As the driver 42 approaches its fully e~rt.on~ position, the tapered frusco-conical portion 42c of the driver 42 initially strikes and contacts the stop member 110. Due to the spacing provided by O-ring 106, the stop member 110 initially is isolated from the mass of stop members 112 and 114. After being impacted by the driver 42, the stop member 110 thereafter is moved axially with the driver 42 against the bias of the O-ring 106. After the resilient O-ring 106 is compressed, the contact surface l lOb of stop member 110 engages contact surface 112a of StOp member 112, which stop member 112 thereafter is moved axially to cu~ ess O-ring 108. Asthe stop member 112 is cont~ct~, it is moved axially against the bias of O-ring 108, causing contact surface 112b of stop member 112 to engage contact surface 114a of stop member 114. This action, in turn, drives the stop member 114 axially to compress the relatively soft resilient stop pad 102 and the relatively hard stop pad 104.
As seer in Fig. 2, the stop pad 104 is supported on a base plate 117 tbat is secured about its periphery to an axial end of the main body 12 by threaded f~tener 119 (only one of which is shown in Fig. 2). Any residual energy from the deacceleration of the driver 42 is absorbed by the base plate which flexes very slightly at its center portion, and by threaded fastener 119.
In accordance with one aspect of the driver stop assembly, ~ub~L~Lially all of the contact force between the driver 42 and stop member 110 is applied through the conical contact surfaces 42c and l lOa. Likewise, substantially all of the contact force between the stop members 110 and 112 is applied through the conical contact surfaces llOb and 112a. Similarly, substantially all of the contact force between the stop members 112 and 114 is applied through the conical contact surfaces 112b and 114a.
W O 96/39283 PCT~US96108390 By interfacing sllhst~nti~lly t~ ,ivc;ly at conical int~rf~re surfaces and focusing snhst~nti~lly all of the contact force between the metal stop members 110, 112 and 114 through these conical surfaces, energy is absorbed by the driver stop assembly without tne creation of a shear plane or other likely failure point.
According to anotber aspect of the driver stop assembly 60, the interface anglesbetween the various metal components increase progressively from the driver interface to the interface with the resilient pad lQ2. As schf~m~tir~lly depicted in Fig. ~, the interface angle A between the stop member 114 and the stop pad (aL)~ xi~ tf ly 90 degrees) (measured with respect to the axis 111) is greater than;the interface angle B
between the stop members 112 and 114. The angle B is greater tban the angle C
between the stop members 110 and 112, which is in turn greater tban the interface angle D (~ hllately 20 degrees) between the driver 42 and the stop member 110.
Thus, the interface angle through which the contact force is applied is progressively increased in the illustrated embodiment from ~ illlately a 20 degree interface angle between the driver 42 and the stop member 110 (approxim~tçly one half of the inrl~
angle of the contact surface 110a) to ~Lo.~illlately a 90 degree angle between the stop member 114 and the stop pad 102.
As also may be surmised from the drawings, the stop member 114 has a greater mass than stop 112, which in turn, has a greater mass than Stop 110. Thus, the effective mass of the driver 42 is increased gradually and non-linearly at an increasing rate to deaccelerated the driver 42. The stop mech~ni~m 60 causes tne driver to deaccelerate in several different ways. In ~ iitinn to the rl~ cçleration caused by the progressively increased effective mass of driver 42 created by the stop members 110, 112, and 114, the O-rings 106 and 108, dissipate energy from the driver 42 during co,ll~les~ion. The O-rings also function to provide a preflPt~rmined spacing between the stop members 110, 112 and 114 prior to contact by the driver 42. This effectively isolates the masses of the stop members 110, 112 and 114 with the result that the dynamics of the u~lle~ull stop members are substantially unaffected by the downstream members upon initial impact. The geometries of the driver portion 42c and the stop members cause each of the stop members 110, 112 and 114 to undergo hoop stress, further dissipating energy from the driver 42. Any residual energy from the driver is ~liccir,.t~otl by the cylinder base plate 12a (see Fig. 2), which cylinder base plate is secured to the cylinder by a bolt 117. In ~ itinn to tneir energy absorbing - 5 characteristics, the resilient characteristics of the O-rings 106 and 108 provide a predPtt-~nine-l space between the stop members 110, 112 and 114, causing these stop members to be sc~Led when the O-rings 106 and 108 are unco~ c:,sed. Hence, while the dynamic interrel,.tinnchip of the various components becomes somewhat complex at high impact speeds, the illustrated stop assembly 60 generally is designed so that as the effective operative inertial mass of the stop assembly applied to the driver 42 is increased, the speed of the driver 42 is reduced, and the contact surface area between the metal components and the interface angle of the impact are increasedprogressively.
The foregoing description of a pl~ft:lled embodiment of the invention has been presented for purposes of illustratiGn and description. It is not inten-led to be exhaustive or limit the invention to the precise form disclosed, and many motlifie ~fi~ nc and variations are possible in light of the above f~rhin~ The embodiment was chosen and described in order to best explain tne principles of t_e invention and its practical application to thereby enable ot_ers skilled in the art to best utilize the invention and various embodiments and with various modifications as are suited to the particular use con~,emplated. It is int~n-led tnat tr.e scope of the invention be defined by the claims appended hereto.
Claims (12)
1. A propellant tool for driving fastening elements, comprising:
a body (12);
a combustion chamber (44) in the body for receiving an ignitable propellant charge (62), the combustion chamber being formed by at least two relatively movable components (80,78) that are operative to receive and compressively engage a propellant charge disposed therebetween; means (64) for introducing a caseless propellant charge contained within a carrier strip into the combustion chamber and for igniting the propellant charge; and a driver cylinder (40) for driving fastening elements, characterized in that the driver cylinder is in fluid communication with the combustion chamber, with one of the relatively movable components having an annular compression surface (98) for contacting an annular surface area of a propellant charge engaged by the relatively movable components and separating a selected surface area of the propellant charge within the annular compression surface from the radially outward portions of the propellant charge surface, the annular compression surface being operative to restrict gas flow between the selected surface area of the engaged propellant charge from the radially outward portions of the propellant charge surface, and an ignition member (66) for contacting the selected surface of the propellant charge and igniting the selected area, whereby ignition gases formed by ignition of the propellant charge in the selected area are forced through the remainder of the charge.
a body (12);
a combustion chamber (44) in the body for receiving an ignitable propellant charge (62), the combustion chamber being formed by at least two relatively movable components (80,78) that are operative to receive and compressively engage a propellant charge disposed therebetween; means (64) for introducing a caseless propellant charge contained within a carrier strip into the combustion chamber and for igniting the propellant charge; and a driver cylinder (40) for driving fastening elements, characterized in that the driver cylinder is in fluid communication with the combustion chamber, with one of the relatively movable components having an annular compression surface (98) for contacting an annular surface area of a propellant charge engaged by the relatively movable components and separating a selected surface area of the propellant charge within the annular compression surface from the radially outward portions of the propellant charge surface, the annular compression surface being operative to restrict gas flow between the selected surface area of the engaged propellant charge from the radially outward portions of the propellant charge surface, and an ignition member (66) for contacting the selected surface of the propellant charge and igniting the selected area, whereby ignition gases formed by ignition of the propellant charge in the selected area are forced through the remainder of the charge.
2. A propellant tool as recited in claim 1 wherein the ignition member is reciprocally movable within the body.
3. A propellant tool as recited in claim 2 wherein the caseless propellant charge is formed of a combustible material (86), an oxidizer material (88), and a sensitizer material (90), and wherein the piercing of the caseless charge is operative to mix the combustible, oxidizer and sensitizer materials.
4. A propellant tool as recited in claim 1 further including an orifice plate (74) interposed between the combustion chamber and the driver cylinder, the orifice plate containing a plurality of orifices (76) providing fluid communication between the combustion chamber and the cylinder.
5. A propellant tool as recited in claim 4 wherein the compression surface is mounted on the orifice plate.
6. A propellant tool as recited in claim 5 wherein the compression surface is integrally formed on the orifice plate.
7. A propellant tool as recited in claim 5 wherein the orifice plate further includes a bore (92) for directing the ignition member into the selected surface of the propellant charge.
8. A propellant tool as recited in claim 6 wherein the ignition member contacts the surface of the propellant charge at an oblique angle and applies a shear force across the selected surface to pierce and ignite the charge.
9. A propellant tool as recited in claim a wherein the orifice plate has a peripheral surface that is press fit into the cylinder, and a radially extending surface that partially defines the combustion chamber, and wherein the compression surface is supported on a pedestal (78) that extends axially into the combustion chamber from the orifice plate.
10. A propellant tool as recited in claim 4 wherein the plurality of orifices are sized to substantially restrict solid components of the propellant charge from entering the cylinder.
11. A propellant tool as recited in claim 10 wherein the orifices has a diameter of from approximately .254 mm (.010 inch) to approximately 1.778 mm (.070 inch).
12. A propellant tool as recited in claim 10 wherein the propellant charge is formed of a combustible material having fibers of an average predetermined length, and wherein each of the orifices has a diameter approximately one-third the average length of the propellant fibers.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/465,283 US5611205A (en) | 1995-06-05 | 1995-06-05 | Apparatus for igniting a propellant charge in a tool |
| US08/465,283 | 1995-06-05 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2222414A1 true CA2222414A1 (en) | 1996-12-12 |
Family
ID=23847155
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002222414A Abandoned CA2222414A1 (en) | 1995-06-05 | 1996-06-03 | Apparatus for igniting a propellant charge in a tool |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US5611205A (en) |
| EP (1) | EP0830242B1 (en) |
| CN (1) | CN1059854C (en) |
| AU (1) | AU696225B2 (en) |
| CA (1) | CA2222414A1 (en) |
| DE (1) | DE69601715T2 (en) |
| WO (1) | WO1996039283A1 (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| USD410182S (en) | 1997-12-31 | 1999-05-25 | Porter-Cable Corporation | Internal combustion fastener driving tool |
| US6006704A (en) | 1997-12-31 | 1999-12-28 | Porter-Cable Corporation | Internal combustion fastener driving tool fuel metering system |
| US6041603A (en) | 1997-12-31 | 2000-03-28 | Porter-Cable Corporation | Internal combustion fastener driving tool accelerator plate |
| US6260519B1 (en) | 1997-12-31 | 2001-07-17 | Porter-Cable Corporation | Internal combustion fastener driving tool accelerator plate |
| US6016946A (en) | 1997-12-31 | 2000-01-25 | Porter-Cable Corporation | Internal combustion fastener driving tool shuttle valve |
| US6045024A (en) | 1997-12-31 | 2000-04-04 | Porter-Cable Corporation | Internal combustion fastener driving tool intake reed valve |
| US6158643A (en) | 1997-12-31 | 2000-12-12 | Porter-Cable Corporation | Internal combustion fastener driving tool piston and piston ring |
| US6321968B1 (en) * | 1998-09-10 | 2001-11-27 | Senco Products, Inc. | Combustion chamber design for propellant charges and power adjustment means |
| DE102005000032A1 (en) * | 2005-04-12 | 2006-10-19 | Hilti Ag | Internal combustion setting device |
| EP3184248A1 (en) * | 2015-12-22 | 2017-06-28 | HILTI Aktiengesellschaft | Combustion-driven setting tool and method for operating such a setting tool |
| US10260830B2 (en) | 2016-02-11 | 2019-04-16 | John Hafen | Smart-gun systems and methods |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2289318A (en) * | 1932-12-14 | 1942-07-07 | Atlas Powder Co | Propellent fuel cartridge |
| BE567130A (en) * | 1957-04-25 | |||
| DE2420089A1 (en) * | 1974-04-25 | 1975-11-13 | Hilti Ag | POWDER POWERED SETTING DEVICE |
| US4804127A (en) * | 1987-09-21 | 1989-02-14 | Master Machine Corporation | Fastener driving gun |
| US4806180A (en) * | 1987-12-10 | 1989-02-21 | Trw Vehicle Safety Systems Inc. | Gas generating material |
| CA2089832A1 (en) * | 1992-03-13 | 1993-09-14 | Brian K. Hamilton | Apparatus and composition for propelling an object |
-
1995
- 1995-06-05 US US08/465,283 patent/US5611205A/en not_active Expired - Lifetime
-
1996
- 1996-06-03 WO PCT/US1996/008390 patent/WO1996039283A1/en active IP Right Grant
- 1996-06-03 CA CA002222414A patent/CA2222414A1/en not_active Abandoned
- 1996-06-03 AU AU61480/96A patent/AU696225B2/en not_active Ceased
- 1996-06-03 EP EP96919033A patent/EP0830242B1/en not_active Expired - Lifetime
- 1996-06-03 CN CN96195456A patent/CN1059854C/en not_active Expired - Fee Related
- 1996-06-03 DE DE69601715T patent/DE69601715T2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CN1190921A (en) | 1998-08-19 |
| EP0830242B1 (en) | 1999-03-10 |
| US5611205A (en) | 1997-03-18 |
| EP0830242A1 (en) | 1998-03-25 |
| AU696225B2 (en) | 1998-09-03 |
| AU6148096A (en) | 1996-12-24 |
| WO1996039283A1 (en) | 1996-12-12 |
| DE69601715D1 (en) | 1999-04-15 |
| DE69601715T2 (en) | 1999-07-15 |
| CN1059854C (en) | 2000-12-27 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |