US2504441A - Governor for portable tools - Google Patents

Description

April 18, 1950 w. G. MITCHELL 2,504,441

GOVERNOR FOR PORTABLE TOOLS Patented Apr. 18, 1950 UNITED STATES PATENT OFFICE.

GOVERNDR FOR PORTABLE TOOLS Walter G. Mitchell, Aurora, Ill., assigner tozlnde.-

pendent Pneumatic Tool. Company, Chicago, Il1. a corporation. of. Delaware Application February 16, 1946, Serial No. 648,065

51Claiins'., l

This invention relates to improvements in governors especially adapted for portable pneumaticall'yA operated tools.

The principal object and purpose of my invention is to locate the governor device withinv the tool motor to simplify its construction and to reduce the overall dimensionsofthe tool for com- Kpactness` and conveniencein handling.

A further object of my invention is to utilize certain of the longitudinal passages in the rotor ofthe motor-'to mount the centrifugally respon sive weight elements of the governor device.

A `further object of my invention is to provide the rotor with a diametric or transversecrossslot to accommodate a cross-bar or other operative part of the governor device for actuating; the valve means controlled by the governor.

A further object of my invention is t provide in the specic embodiment herein shown a, cam connection between the weight elements and the cross-bar to insure movement of the latter in opposite directions in response to the valve'spring' and centrifugal force, respectively.`

The invention consists further in the structural features and combination of parts` hereinafter described' and claimed.

In the accompanying drawings- Fig. I is aside elevational view, partly in longitudinal section,` of a portable pneumatically operated impact tool having a governor device located Within the tool motor in accordance with.

my invention;

Fig; 2 is a diametric sectional, view taken on line 2.-2 of. Fig. 1;

Fig. 3 is a longitudinal sectional view on a larger scale and detailing the governor device, said section being, taken online 3-3 oflig. 2.;

Fig.,4,.is an elevational view of,I oneY of the weight,

elements, of the governor removed from the tool; Fig. 5 is a top plan view oi the. cross-bar of the, governor device, also removed from the` tool.

for the purposes of. illustration;`

Eig, 6. is aside viewof a. weight elementprovided with an increased mass. on4 one side.;

Fig.` 7 isa top plan view ot said modified weight element;

Fig. 8 is a fragmentary vertical sectional view with parts. in` elevation of a modifiedV forml of governor construction to` be hereinafter described; and

Eig.v 9 is a horizontal sectional-,view taken on line 9.-9of Fig. 8 tofshow a. detail of. construction.

The too'lshown in4 Fig. vl has: a rotary motor iandV an. outer casing 2 comprising an; upper sec-- tion 3- housing the motor and, aloweriseotion. tA

housing the impact clutch of the tool, said clutch having a spindle 5 extending from the lower end of the tool to mount and drive a nut or bolt en.- gaging socket 6 as in tool devices of this char-` acter.

The tool has a side handle 1 through which extends a passage (not shown) containing a spring biased throttle valve 8 tocontrolthe main supply of pressure fluid or compressed air' to the tool motor i for operating it. The air supply hose (not shown) is connected to the handle 1 at its outer end, there being a hose connecting'fixture El at' such end o1 the handle as is shown. The valve 8 is the starting and stopping valveA of the tool and is opened by depressing a trigger block il! slidably mounted in the handle l.

The tool motor i, being of the rotary type, hasa rotor H' having blades i2 operating in radial slots I3 in the rotor and a cylinder HlV closed at its opposite ends'by'end plates Iii, I5. 'The motorcasev or section 3 in conjunction with cylinder i4 are provided' with a portingV system for operating the rotor Il in reverse directions as in tools ofl the character displayed. The impact clutch is of the character which delivers rotational hammer blows to the spindle 5 for nut and bolt tightening and loosening purposes, respectively. The lower trnnnion ltofthe rotor l! extends through the` lower end plate l5 and is splined or directly connected with the clutch shaft il.

Formed in the motor case 3 at one side of the tool motor is a supply passage I8 connecting withA a cross-passage i9 in the top part of the tool case above the` motor I. The passage l5 is divided by a Xed. sleeve, or housing section 2l! having, diametric ports 2l', 22, the port 2l connectingr with` the'passage section i911 and the port 22 connecting with thev passage section ISb. The latter section |919` leads to an inlet port 23 ofthe porting system of the tool. The reversing mechansm for this porting system need not be shown, form-ing no part of the present invention.

The governor device for the tool in accordance with. my invention is located within the rotor Il for compactness. and to reduce the overalllength to the tool. This governor device in its preierred form is constructed as follows:`

TheY rotor H. of the tool motor to lessen its Weight is providedV with the usual axially exe. tending, circumferentially spaced, cylindrical chambersorpassages; fiflf. Two diametrically opposite of these passagesor `bores 24a,V 2do: are' employed to: mount and house the centrifugalv Weights 2e* 25 of the governor device.. There is one Weight in each passage 24a; and,- as; shown in Fig. 3, each weight 25 rests at its lower end on a plug 26 tightly tted within the passage 24a and closing its lower end. Here, the lower end of the weight element 25 is rounded and seats in a concave socket or recess 2l so that the weight element will readily rock or tilt in response to centrifugal force and spring pressure, respectively. Each recess 21 is oiiset outwardly from the longitudinal center line of its passage 24a, whereby the weight elements 25 will stand at inwardly tilted angles on opposite sides of the rotor axis when the governor device is at rest.

The weight elements 25 extend along their respective passages 24a, and have their upper inner ends beveled at 23 to increase the angle at which the weights stand when at rest. At this time, the weights 25 bear against sleeves 29 fitted in the passages 24a to close openings or slots 3!) at their outer sides as shown in Fig. 3. The sleeves 29 t between the plugs closing the opposite ends of the passages 24a, the upper plug being marked 3i. The sleeves 29 are removed to open the slots 3G to insert the cross-bar 32 or equivalent means into or remove it from the rotor Provided in the rotor il in the region of the upper beveled ends of the weight elements 25 is a transverse or cross-slot 33 opening into the passages 24a and aligned with the slots 3U as shown in Figs. 2 and 3. Located in the cross-slot 33 is the laterally narrow cross-bar 32 having its end positions 34, 34 iitting in bifurcations 35 at the upper ends of weight elements. The crossbar has downwardly and outwardly inclined surfaces 36 at its ends to co-act with complementary shaped cam surfaces 3l at the bottoms of the bifurcations 35.

Located in the housing 26 in axial alinement with the rotor Il is an inlet valve 38 subject to the control of the governor device. Said valve 38 is slidably mounted in the housing 20 and has a depending stem 33 extending downwardly into a bore in the upper trunnion ri of the rotor Ii. Said valve 33 is biased to open position by a coiled spring 4i contained within the housing 26 and retained therein by a screw-cap 42 closing its upper end.

Also mounted in the bore in the upper trunnion 40 of the rotor ii is a rod i3 tting between and engaging the cross-bar 32 and the valve stern 33, respectively. The spring 4i holds the parts in contact and under the desired tension as shown in Fig. S, the upper end oi the rod being against the valve stem 3Q and the lower end of the rod being against the cross-bar 32 within the crossslot 33. The arrangement described and shown holds the end portions 34 of the cross-bar 32 in the bifurcations 35 and the inclined surfaces 35, 3'1 in Contact or operative engagement.

The governor device shown and described operates as follows:

When at rest or not overcoming the tension of the valve spring 4 i, the weight elements 25 stand in their inwardly inclined positions as shown in Fig. 3. The ports 2i, 22 are at this time fully open and the valve 38 furnishes a full volume o1 compressed air to the tool motor i from the throttle valve 8. Under speed of the motor l centrifugal force tilts the weight element 25 outwardly and the cross-bar 32 is moved axially to close or partially close the valve 33. This reduces the airvolume furnished to the tool motor and the latter rotates or idles at the desired speed, a limited supply of live air being supplied t the motor through the valve 38.

When the tool is applied to the work, its speed of rotation is reduced by the impressed load and the weight elements 25 are moved into their inwardly tilted positions by the downward pressure or action of the spring 4l as it opens the valve 38.

The outward tilting movement of the weight elements 25 is by centrifugal force and the crossbar 32 serves to move the valve 38 towards closed position. The movement of the cross-bar 32 in the opposite direction by the valve spring 4l returns the weight elements 25 to their inwardly tilted positions when centrifugal force is reduced. This movement is due to the coaction of the inclined or cam surfaces 35, 31 at the ends of the cross-bar 32 and on the weight elements 25, respectively. An outward movement of the weight elements 25 raises thecross-bar 32, while a downward movement of the cross-bar 32 moves the weight elements to their inwardly tilted positions.

. To increase the mass of a weight element 25 to make it more responsive to an inward tilting movement and centrifugal force, I may increase the section of the weight element en its inner side as indicated by the dotted line a in Fig. 3 and full lines in Figs. 6 and 7. In the last two gures the modified weight element is marked 25a.

The cross-slot 33 intersects or opens into the passages 24a as heretofore mentioned. The sleeves 29 are slotted at 44 to register with the cross-slot 33 to oier no interference to the -passage of the cross-bar 32 into and out of the passages 24a. The governor is assembled by inserting the cross-bar 32 into the cross-slot 33 through one of the side openings 3i? in the rotor li and then the weight elements 25 are placed in the chambers 24a astride the ends 34 of the cross-bar, the bifurcations 35 of the weight elements serving this purpose. The sleeves 29 are then inserted into the chambers 24a to close the outside openings 30 and the plugs 26 and 3i are fitted into the opposite ends of the chambers to hold the sleeves 29 in place. The cross-bar 32 being laterally narrow makes the slot structure 3d, 33, 35 and i4 similarly narrow and the governor parts may be made to t within the coniines of a tool rotor Il of a relatively small size.

The modified construction of my invention as shown in Figs. 8 and 9 employs centrifugally responsive spherical or ball elements 25h, 25h within the rotor l I instead of the pivoted weight elements 25. The ball elements 25h are mounted within the tubes 29a, 29a on transverse lands or trackways 45 therein in the region of the cross-slot 32a in the rotor as shown. The cross-bar 33a extends through said cross-slot 32a as in the previous figures, and has its end portions t@ in the axially extending chambers 24a with inclined surfaces 41 co-acting with the ball elements 25h as detailed in Fig. 8. The tubes 29a close the side openings 30 in the rotor as before. As shown in Fig, 8, the ball elements 25h are stopped by tapered portions 48 made by drilling in the rotor at the inner ends of the track-ways. ating rod Iii-l engages the cross-bar 32a and is lifted by the ball elements on their outward movement in response to centrifugal force cn the rotation of the rotor. This lifting action of the rod 49 at an increase in speed closes the valve 38 as before, the ball elements 25o having the diameter for the purpose.

With the governor device located and housedl Within the tool motor in accordance with my invention, the tool is considerably reduced in over- The valve stem or actumore compact for ease in handling and manipulation. With the governor weights or their equivalents located within the passages or bores 24a usually provided in the motor rotor, the governor device is adequately housed and the design is simple and inexpensive in construction.

The details of construction and arrangement of parts shown and described may be variously changed and modied without departing from the spirit and scope of my invention, except as pointed out in the annexed claims.

I claim as my invention:

1. In combination, a pressure fluid actuated rotary motor having a rotor, a valve for controlling the supply of pressure fluid to said rotor, 1;,

means for opening said valve, and governor means responsive to centrifugal force in the rotation of the rotor to close said valve, said governor means being carried by and housed within the rotor and having a cross-bar comprising a 1,A

thin flat plate extending cross-wise of the rotor in a narrow diametric slot therein in a plane coincident with the axis of said rotor and the walls of said slot closely conforming to the sides of said plate for slidable engagement therewith, and elongated centrifugally responsive elements located at and operable on the opposite end portions of the cross-bar in closing said valve, said elements acting on inclined cam surfaces at the ends of said bar, said elements and the valve being located on opposite sides of the bar in the axial direction of the rotor, said elements extending longitudinally of the rotor and co-acting at its opposite ends on the rotor and the bar, respectively.

2. In combination, a pressure fluid actuated rotary motor having a rotor, a valve for controlling the supply of pressure iluid to said rotor, means for opening said valve, and governor means responsive to centrifugal force in the rotation of the rotor to close said valve, said governor means being carried by and housed within the rotor and having elongated weighted elements located in and extending lengthwise of axially extending chambers in the rotor on opposite sides of and substantially parallel to its rotary axis, said elements being tiltably mounted on one of their respective ends in said chambers and being formed with bifurcations at the other of their respective ends, and a cross-bar in a diametric slot in the rotor between and opening into said chambers, said cross-bar having its opposite ends in said chambers and extending through said bifurcations in the adjacent portions of said elements and said bifurcations being of greater length and extending beyond the portions of the cross bar extending therethrough for increasing the effect of centrifugal force thereon, and complementary inclined surfaces on the cross-bar and at the bottoms of the bifurcations, respectively.

3. In combination, a pressure iiuid actuated rotary motor having a rotor, a valve for controlling the supply of pressure fluid to said rotor, means for operating said valve, and governor means responsive to centrifugal force in the rotation of the rotor to close said valve, said governor means being carried by and housed within the rotor and having elongated weighted elements located in and extending lengthwise of axially extending chambers in the rotor on opposite sides of and substantially parallel to its rotary axis, and a cross-bar in a diametric slot in the rotor between and opening into said chambers, said cross-bar having its ends in said chambers and operated on by one of the corresponding end portions of the weighted elements in the closing of said valve, and plug members closing the lower ends of the chambers and having curved recesses providing tiltable mountings for the other corresponding ends of the weighted elements in said chambers.

4. In combination, a pressure fluid actuated rotary motor having a rotor :having longitudinally extending chambers on opposite sides of and substantially parallel to the rotary axis of said rotor, a cross-slot in said rotor between and intersecting said chambers, a valve for controlling the supply of pressure uid to said rotor, means for opening said valve, governor means responsive to centrifugal force in the rotation of the rotor to close said valve and having centrifugally responsive elements and a cross-bar in said chambers and the cross-slot, respectively, said chambers having side openings in the outer side of the rotor to pass said bar in its insertion into and withdrawal from the cross-slot in the rotor, and means carried by the rotor for normally closing said side openings.

5. In combination, a pressure fluid actuated rotary motor having a rotor having longitudinally extending chambers on opposite sides of and substantially parallel to the rotary axis of the rotor, a cross-slot in said rotor between and intersecting said chambers, a valve for controlling the supply of fluid pressure to said rotor, means for opening said valve, governor means responsive to centrifugal force in the rotation of the rotor to close said valve, said governor means having centrifugally responsive elements and a cross-bar in said chambers and the cross-slot, respectively, said chambers having Side openings in the outer side of the rotor to pass said bar on insertingl it into and withdrawing it from said slot, said side openings being in alignment with said slot, and tubular members in said chambers to open and close said side openings.

WALTER G. MITCHELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 824,648 Hamann June 26, 1906 1,208,421 Watts Dec. l2, 1916 1,917,054 Norling July 4, 1933 1,947,009 Jimerson et al Feb. 13, 1934 2,096,741 Fried Oct. 26, 1937 2,141,772 Stadler Dec. 27, 1938 2,146,046 Bancroft 1 Feb. 7, 1939 2,246,910 Amtsberg June 24, 1941 2,261,204 Amtsberg Nov. 4, 1941 FOREIGN PATENTS Number Country Date 618,780 France 1 Dec. 21, 1926 Certicate of Correction Patent No. 2,504,441 April 1s, 1950 WALTER G. MITCHELL It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction asfollows:

Column 5, line 63, for the Word operating read @pento-g;

and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Of'ce.

Signed and-sealed this 18th day of July, A. D. 1950.

[sul

JOE E. DAN IELS,

Assistant ommzfssioner of Patents.

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