US2547174A - Fuel injector mechanism - Google Patents

Description

April 3, 1951 G. M. ROGERS FUEL INJECTOR MECHANISM 2 Sheets-Sheet 1 Filed July 3, 1946 F/g Z INVENTOR. GAED/NEE M. Foes/25 Patented Apr. 3, 1951 UNI TED 1S TAT ES fPAT-ENT ICE FUEL nneoroa Gardiner M. "Rogers, Ithaca, Y.

Application July 3, 1946, :Serial No, 582L329 a Claims. (01403- 41) 11 v .flhls invention relates to an improvement in fuel-injectors for. internal combustion, engines, particularly of the Diesel type and specifically to various improvements particularly applicable to aiuel injector embodying the essential principl oi myapplication Serial No. 508,588, filed August 2, 1945. The injector shown in said application differs from the usual jerk pump in several ways, the principal ones bemg; la) the beginning of injection is determinedby pening of. a delivery portleading from. ahelix cavity to the atomizin nozzle, termination be n effected by openin 0f the helix cavity to. a spill. port, and (b) provision -01 asimple and accurately calibrated pressure a control valve communicating with the metering initiating and completing helix and cavity Portions of the plunger that all the adjustment from tno injection to full load injection had to be accomplished "by relative rotation of the plunger and its cylinder through less than half a circum- .Terence. VOne improvement hereof (indicating :a

one object) is to provide, in a non-positive displacement; injector, separate delivery and spill initiatingv control edges helices} so that the ad- "mstment from no ection to "-full load injection canbe accomplished by relative adjustment 2 Y but yieldably holding the ball in sealing relation to a. relic: port of the pump pressure chamber, which spring is. never subject to localized wear and operational stress but operates continuously to. change pos tion the v v ass mblylAfiurther object is to provide an improved atomizing nozzl a sembly for a f l i ie c wherein the atomizing nozzle orifices, can be more simply vformed th n by u e of the usual dril n i operation will be subject to easy cleaning and wherein the essential operating Parts of h no l are capable of being permanently locked in the desired relative positions insuring that all iniectors oi a set wi l have unif rm at nuzi operation- Further objects include provision of a self ,valying plunger and cylinder type controlled, pressure injector pump in which the [possibility of material axial distortion of the cylinder by injection impact force is reduced,

Other objects and features of :the invention will "become apparent from the following description of, the exemplar embodiment shown by the accompanying drawings wherein:

Fig. 1 is a'central longitudinal assembly view I .Qf a unit injector incorporating principles of the present invention;

Fig. 2 is an enlarged fragmentary sectional detail view of the atomizing nozzle taken along the line 2-2 on Fig, 1';

Figs. 3 and 4 are crosssectional detail views of the nozzle mechanism as, indicated by the lines oi the plunger and cylinder through a much greater angle than half a circumference, for ex- ?J file through nearly a :full circumference, whereby the slope of the control helix edges may be greatlylessened and the sensitiveness of the sure non-positive displacement injector whereby sspeeelreg l tionmay be accomplished very gradmay, a cularly at idling and cranking speeds,

=by'rrelative rotational adjustment of the pump plunger and cylinder.

"Arm-the r object is to previde improved mressiu eregulating valve for a controlled presactor pump, andspeeifieally a valve b all and an amulet-,1 spring normally Fig. '5 is an enlarged transverse cross sectional detail view of the controlled pressure regulating valve taken along the line 5-5 on 'Fig. 1;

Fig, 6 is an enlarged side elevation of the -in-.

jectorpump plunger according to Fig. 1;

Fig, "7' is a. development view of "t v vine portion cit-he plunger showing the control helices "and associated recesses formed on the plunger,

but omitting the fuel supply ports leading to sai --re ces ses from/Within the plunger;

*Inelc-avity :or'reservcirt through suitable'ports and deliver the fuel to a nozzle mechanism generally shown at 4 under very high pressure in proper relationship to the compression stroke of the engine cylinder served. The unit injector as shown herein includes a main body member receiving, in a counterbore 5 of the body, a reduced diameter upper portion of the pump cylinder or bushing 2. The body 5 is threaded as at G'for engagement with a sleeve-like nut i which enters the associated engine cylinder as through the cylinder head water jacket and supports the nozzle mechanism 4 in communication with the combustion space of the cylinder. The sleeve-like nut has a shoulder at' 8 for engagement with a suitable gasket (not shown) around an opening in the cylinder head, and a reduced diameter portion 9 which fits a smaller bore in the cylinder head and is held therein by suitable means (not shown) which engages the body -5 and forces the shoulder 8 against the cylinder head.

The fuel cavity or reservoir .3 is formed as an annular space between the bushing 2 and sleevelike nut 1, said space being sealed at its top end partly by an upper shoulder in of the body 5 against which the bushing 2 is seated when the .sleeve-like nut is threaded to the body at 6. The

lower end face I! of the bushing 2 abuts a coaxial base piece in the form of a recessed block l2. The base piece is one of a plurality of stacked centrally apertured injector parts fixedly sup- ..ported in and by the sleeve nut as will be described later.

' The fuel cavity 3 is supplied with liquid fuel through a supply pipe [5 leading to a filter chamber l6 containing a filter unit H, the outlet of 'the filter communicating with a supply duct (8 in the body 5 entering the upper end of the fuel cavity.

The bushing 2 has a single transverse bore 28 leading to the lower end or pressure chamber portion P of the cylinder bore 2| of the bushing just be ow the lower end of the plunger when the 4 nozzle. In event the valve plug 36 refuses to close as by reason of accumulation of foreign matter on the valve seat, combustion pressure may force combustion gas back into the injector through the delivery ducts, and to prevent that from occurring the valve chamber 21 may be provided with an apertured check valve disc 39 latter is in its raised or inactive position. The

lower end of the cylinder 2| is closed by a central imperforate portion of the base piece or block l2. The single port 29 forms both a supply port and spill port for the valving mechanism of the injector plunger, wherefore the compression resisting cross section of the bushing is reduced a minimum amount to provide for supply and spill. Above and diametrally opposite from the port 28 is alateral delivery port 23 intersecting a vertically extending or axial bore 24 which is open at its lower end only for communication with an annular trough or channel 25 on the top side of the block 12. The latter has an oblique duct 25 leading centrally of the assembly to a check valve J chamber 2?. The check valve chamber is formed -in a circular valve body 28, one of the stacked zle fitting and valve body 28 have central com- -I nunicating bores 34 and 35 respectively. The ;bore 34, containing a suitab e main spring closed .check valve plug 36 which, between injection ;;strokes of the plunger, closes the bore 35 against flow of fuel from the delivery duct toward the which floats vertically in the chamber 21 and can be forced by suchback pressure of gas from the combustion space against the fiat face of the body l2 so as to seal off the delivery duct.

The lower end of the bore 34 of the nozzle fitting ill is partially closed by a screw 40, the head portion 4% of which has a conical face 42 seating against a generally conical face 43 on the lower end of the injector fitting. The conical face of the screw head forms partial wall portions of respective atomizing nozzle orifices 44. The remaining walls of the orifices 44 are formed as grooves or channels in the conical terminal face so that fuel can pass downwardly freely along the shank of the screw to an enlargement of the threaded bore indicated at 41 above theconical face 42 of the screwhead and generally closed thereby. It is importantthat each individual orifice 44 be maintained accurately within very close tolerances and, assuming the channels have been accurately formed, the actual cross section of each of the orifices may be regulated to a slight extent by pressure of the conical face 42 against the complementary end face of the nozzle fitting.

To adjust the pressure between the conical faces,

the screw may be turned to head seating position as by engagement of a suitable tool with a non-circular recess in the screw head. The preferred form of locking detent for the screw comprises a locking rib 52 at one side of the nut head designed to enter a selected one of a series of complementary grooves 53 formed on the head.

The grooves may be formed simply as parallel serrations on the head. .The lockin detent 52 is in the form of a spring arm which extends from a longitudinal recess 54 in one side of the nozzle fitting 3|, being-staked into place as by indentations 55, Fig. 3, of the side walls of the channel 54 overhanging the rectangular shank of the detent. The free portion of the detent beyondthe lower end of the sleeve nut l constitutes the spring arm of the detent. While the screw can. be turned to various positions without removing the detent. the latter, principallyby reascn of the short length of the free portion, is

fully efiective by engagement with the notches in the screw head to maintain the setting of the screw against being jarred out of position by engine vibration. The detent arm is a fixed part and cooperating fuel rack 58.

of the nozzlefitting and the fitting, screw and detent can be withdrawn from the sleeve as a unit without disturbing the adjusted seated position of the screw head. I

- v The pump plunger is adjusted as usual for engine regulation by a gear 51 keyed to the plunger The lower or valving and-piston portion of the plungerhas three sets of cylindrical lands designated 60, 6|

or raised'position of the plunger, the supply'and spill port (at 200:, Fig. 7) is uncovered by the lower land 68 and the delivery port, at position 23x, lies above the helix edge 65 but below the lower edge of the land 6!, and thus is open. Downward travel of the plunger causes the land 6| to close the delivery port before the land 50 closes the supply port and thereupon both ports will be closeduntil the plunger has lowered to bringthe helix edge 56 into cracking relation to the delivery port as at 231:. In that descended position of the plunger, the relationship of the "spill port (see 26:11) to the spill helix 85 is such 'that shortly after opening of the delivery port the spill port will be opened by the horizontal portion of the helix 65 to terminate injection. The illustrated relative position of ports and plunger helices is an idling or cranking reguiating adjustment of the plunger and it will be seen that, with the developed plunger surface moved "further to the right (such port and helix relationship not illustrated), the delivery port will be opened earlier during the downward stroke of the plunger, causing injection of longer du- Lration. A ,no injection adjustment of the plunger is illustrated in Fig. 7 by the relation-- ship of ports and helices brought out by comparison of port positions 28y and 23;; as though moved along the lines Y and Y respectively. In that adjustment, a horizontal portion of the spill helix 65 opens the port 213 as before but, in this case, simultaneously with the delivery port opening operation of a horizontal portion 'of the helix 65. The concavity of the helix edge '65 in the zone 65a is in order to obtain an extremely gradual increase of fuel from no injection relative position of helices and ports toward initial fuel delivery relative position. -Relative positions of ports and helices shown by the relatively reversed positions 292 and 232 (along lines Y and Y respectively) further illustrate the coaction of the sloping surface por tions of both helices in an intermediate fuel regulating position of the plunger. The same ef- "fect can be had by a less gradual dropping off of the helix 56 from its no injection or hori- 4 zontal high portion downwardly along the slope as indicated, for example, by the broken line 66b. -'In the event the less gradual slope 66b is used, then a non-concave slope would be used on the spill helix in the zone 65a. The helix relationships are illustrative only since, as well known inthe art, helix designs are varied as required for most efiicient engine operation. slopin of the control edge 65 for spill enables less slope to be used on the delivery helix.

Since the delivery helix may extend for a sub- ---stantial distance "around the plunger greater than 180, the slope of 'both'heli'ces may be much less than in the case such as illustrated by my copending application, wherein the delivery port and spill port are opposite each other and less Ithan half of the circumference of the plunger must be used for spill and delivery respectively. Figs. 8 and 9 illustrate first that only one of thecavities D or S needs to have an inclined edge for fuel regulation adjustment by turn me of the plunger. The fuel adjustmentfrom off to maximum speed is overned by the inclined control edge portionv IfiBa of the cavity edge 66; The entire upper limitledge 165) of the land I6!) is shown as horizontal with the exception of a short depressed portion i651) which may be termed a stop loop. The stop 100: durin d s t f t pl n er. efiects opening of the spill port, diagrammatically indicated in an associated position at IZOx, when the dclivery port at I231: is still closed by the land NH. The stop loop affords an opportunity for the fuel in the pressure space P to begin to be bypassed to the fuel reservoir well before the delivery port is opened by the descending plunger at the high horizontal portion of the edge I65.

In relatively large injectors, the plunger displacement is sometimes such that the rate of fuel bypass discharge through the spill port is insufficient to prevent delivery of some fuel to the nozzle in the off osition. In such cases, an unused portion of the cavity D can have a. by-pass channel formed in the land IBI as at ill leading to the cavity S to provide a direct path for fuel from the cavity D to the spill port in addition to that provided by the center bore 61 (see Fig. 6) and the cross bores 58 and 69. When such alternate and more direct path is available, there i no likelihood'of fuel being forced to the nozzle in the off positions of the plunger. Alternatively, the helix cavity D may terminate between the high and low portions of the helix edge 166a so that in the off position of the plunger the delivery port cannot be unsealed by the cavity D. A suitable circumferential portion of the cavity may thus be blocked off within the limits of the dimensional indication H0 on Fig. 8. Figs. 8 and 9 also illustrate provision of a pre' liminary injection relief extension of the delivery helix for the purpose of reducing detonation. Detonation is most troublesome during idling and cranking speeds. The relief may be formed bya region of slightly reduced diameter on the plunger land [8! as indicated at 16Gb on Fig. 9, at the idling speed control portion only of the edge lfifia. The relief is very slight, being for example about .9097" in a plunger having a valve land diameter of about .275". The preliminary injection relief portion [66b of the delivery helix functions slightly to open the delivery'port to start injection during the descent of the plunger earlier than it normally would be opened by the main inclined portion of the helix. Thereby, a small amount of fuel is caused to be injected into the cylinder during the compression stroke ahead of the main charge. When the main charge enters the cylinder, it is ignited by the already burning preliminary injection charge, thus greatly reducing or eliminating detonation. v An illustrative relative idling position of delivery port and spill port is given on Fig. 8, wherein 523g indicates the partially opened position of the delivery port just before the spill port at I201! opens to terminate injection. It is apparent from the showing that the preliminary injection period which commences as soon as the delivery port intercepts the relief zone I661) of the plunger ,is followed by a main injection period of rela- A tively short duration.

For adjusting andoperating the plunger 1, a conventional arrangement is shown; Fuel adjustment comprises the adjusting gear 51'- and rack 58. The gear is supported between the top end of the bushing 2 and a shoulder 8| within the body. The gear is, in effect, splined to the w i h p n. a so. acts asalimit stop for-the follower guide in a well known manner. Above the somewhat enlarged head portion of the plunger is a follower or tappet piece 88 secured to the follower as by a cross pin 89. The engine rocker arm 90, through a suitable roller 91, operates the plunger against the opposing force of a plunger return spring 92 around the follower and supported against the top face of the body 1. The lower end of the spring holds the key pin 31 in place as will be evident.

I claim:

1. A fuel injector pump of the reciprocating type, comprising a cylinder which is closed at one end and a plunger fitting the cylinder to form a pressure chamber at the closed end and retractable to a predetermined position away from the closed end to commence its pressure stroke, a supply port intersecting the cylinder beyond the end of the plunger in its retracted position, two axially spaced circumferentially extending valving cavities in the plunger continually communicating with each other and with the pressure chamber, a delivery port intersecting the cylinder and located so as to be opened by one of the cavities to commence injection, the other cavity being located so as later to open the supply port for fuel-spill to terminate injection and restricted fuel-venting means connected with the pressure chamber during the pressure stroke of the plunger and controlling the injection pressure of the pump.

2. An engine fuel injector reciprocating pump comprising a cylinder and a plunger fitted thereto and forming with the cylinder a pressure cham-- her at one end of the plunger, said plunger being movable from a full retracted position to a full advanced position, combined supply and spill port means intersecting the pressure chamber and located beyond the end of the plunger in its full retracted position, two axially spaced circumfer entially extending valving cavities in the plunger communicating with each other and with the pressure chamber, a delivery port intersecting the cylinder in position to be opened at one part of the plunger stroke by the cavity which lies the more remotely of said end of the plunger to commence injection, the other cavity during another part of the same stroke opening the supply and spill port means to terminate injection and restricted fuel-venting means connected with the pressure chamber during the pressure stroke of the plunger and controlling the injection pres sure of the pump.

3. A fuel injector pump of the reciprocating type, comp-rising a cylinder which is closed at one end and a plunger fitting the cylinder to form a pressure chamber at the closed end and retractable to a predetermined position away from the closed end to commence its pressure stroke, a supply port intersecting the cylinder beyond the end of the plunger in its retracted position, two axially spaced circumferentially extending valving cavities in the plunger continually communicating with each other and with the pressure chamber, a delivery port intersecting the cylinder and located so as to be opened by one of the cavities to commence injection, the other cavity being located so as later to open the supply port for fuel-spill to terminate injection, and a pressure-control restricted vent means for the pressure chamber including a port in the cylinder so located as to be open to said one cavity at such The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,588,046 Nelson June 8, 1926 1,854,009 Wilkinson Apr. 12, 1932 1,860,862 LePul May 31, 1932 1,917,169 Vigers et a1 July 4, 1933 1,944,371 Ritz Jan. 23, 1934 1,953,449 Thege et al Apr. 3, 1934 1,966,694 Vaudet et al July 17, 1934 1,974,851 Hurst Sept. 25, 1934 1,995,459 Olsen Mar. 26, 1935 2,012,128 I-Iesselman Aug. 30, 1935 2,174,526 Parker Oct. 3, 1939 2,211,496 Davidson, Jr Aug. 13, 1940 2,265,278 Goldberg Dec. 9, 1941 2,378,165 Waeber June 1'2, 1945

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