US2393544A - Fuel injection pump - Google Patents

Description

Jan. 2v2, 1.946. y G. P. LUM

FUEL INJECTION PUMP Filed Aug. 5, 1943 IlIlllIlll/l 659,765 Ua/V BY ATTMA/EY IN VENT 0R Patented Jnn. 2,/1946v Bendix Aviation Corporation,

South Bend,

Ind., a corporation of Delaware Anpunnunn August 5, 1943, senni No. 491,529

11 Claims.

This invention relates -in `its broader aspect to means for eecting ne adjustments in mechanical devices, and is particularly shown and described herein, by way of example, as appliedto mechanisms for adjusting the effective pumping strokeof plungers `or pistons of rfuel injection pumps. I I

As is well known in therart, it is highly desirable `to have extreme accuracy in the metering of the fuel delivered by fuel injection pumps to the end that the quantities of fuel delivered by the individual plungers of the pump should be as nearly equal as possible. It is also important in pumps ofthis character t'o time the delivery of Y the fuel with extreme accuracy, both as to the commencement of the delivery stroke and as to the ending thereof, but even'with careful precision manufacturing methods it has been found in practice that there are unavoidable variations in the diameters of the variousl plungers or pistons, the spacing of the cut-od annali and fuel ports, et cetera. lhese variations result in a de'- livery of unequal quantities of fuel from the individual pump plungers which causes uneven operation of the engine, a, loss in maximum available power, and a decrease in engine performauceand' economy. Various means. have been proposed heretofore to adjust the edective fuel delivery stroke of the various plungers of fuel injection pumps to' compensate for the-aforo? have not proven entirely ksatisiactory for various reasons. f

llt is therefore an important object of the present invention to provide means for adjusting vthe edective stroke of the plungers of fuel injection pumps with extreme accuracy to compencate for various inaccuracies inthe manufacture of the pump', plungers and operatively associated parts which adversely .affect the uniformity inthe fuel delivery from the individual plungers oi' the pump.

Another object of the invention is tov provide means for effecting a fine longitudinal adjustment which may be particularly useful in connection with sleeve assemblies for fuel pumps of the above type but which is capable of general application in arrangements wherein a une longitudinal adjustment is requiresl between ndjacent or cooperating parts.

It is another object of the invention to'prosimple and effective locking means for retaining'the assembly in adjusted positions, said locking means being readily releasable for making adjustments.

Still another object of the invention is to providenovel means for making various extremely accurate adjustments between parts of a mechanism.

The characteristics and advantages of the invention are further suiiiciently referred to in connection with the following detailed 'description of the accompanying drawing, which represents a preferred embodiment of said invention. After considering this example, skilled persons will understand thatfthe adjustable mechanism, here disclosed is suitable'to many uses, and that many variations may be made without departing from the principles disclosed; and I contemplate the employment of any structures,

arrangements, or modes of operation, that are properly within the scope of the appended claims.

in the drawing: y Figure l is a sectional view of a fuel injection pump embodying the present invention;-

iiligure 2 is a longitudinal section of the adinstable by-pass sleeve assembly: @11d Figure 3 is an isometric exploded view of the parts ofthe by-pass sleeve assembly.

Referringmore particularly to the fuel injection pump shown in Figure 1, said pump includes va main drive shaft it which drives a member l2 'im through an Oldham type universal coupling of mentioned manufacturing variations, but these known construction, indicated at llt. A locating pin lo `is provided to prevent incorrect assembly of the coupling which would change the ially arranged relative to the tappets to and are slidably received in bushings 26 which form the individual pump cylinders. In view of the fact that each ofthe tappet and plunger assemblies and the control mechanism therefor are all alike, the following detailed description will be directed to the upper plunger and tappet. A spring 28 cooperates with a washer' supported on a horseshoe or split retainer 29 received in"a groove in the plunger 24 and urges the plungerto the left,

maintaining the plunger and tappet in con-l stant contact with each other and maintaining vide an arrangement of this character having toY thetappet against the wobble plate I8. yThe plungerand tappet are preferably made as separate abutting pieces rather than as one piece, so that minor variations in alignment of the bushings .22 and 28 may be accommodated without tending to bind the assembly. A spring 30 is provided to move the tappet out of engagement with the wobbleplate in the event the plunger 24 becomes stuck. 'I'he pumping plunger 24 is provided with a central bore 32 in communication with a pair. of spaced annuli 34 and 36. An externally threaded by-pass sleeve or member 38, best shown in Figures 2 and 3, is slidably mounted on the plunger 24' and includes an 'outwardly extending ilange 48 having a plurality of notches 42 equally spaced about the periphery thereof. Threadably received on the sleeve is a member 44 which is carried by a plate 46the latter being provided circumferentially with' spaced apart notches adapted to be snugly received in a grooved portion 48 of the member 44. The plunger 24 prevents the assembled sleeve 38 and member 44 from sliding out of the cooperating notch and the sides of the groove 48 prevent longitudinal movement of the member 44 relative to the plate 46. Although the width of the groove 48 is such that there is no longitudinal movement of the member 44 relative to the plate said member is. free to rotate within the notch of the plate, it being considered desirable to allow such rotation. The end of the member 44 adjacent the ange 40 of sleeve 38 is provided with an annular coaxial recess 58 and an annular flange-like wall 5| projecting toward the ilange 48, the wall 8l being provided with a plurality of notches 52 equally spaced circumferentially of said flange. In the form illustrated the ilange 48 is' provided with one more notches than is the wall however the number of notches on the Wall and ange may be 8 varied to obtain any desired iineness of adjustment. Means for locking the sleeve in adjusted positions comprises a spring 64 carried by and disposed about the sleeve 38 and the adjacent end portion 58 of the grooved member 44. This spring is provided with a bent end section 88 the free end of which is adapted to be selectively received in notches 42 of the flange 48 and a curved portion 68 at the other end-of said section 88 is arranged to selectively engage notches 82 of the member 44, it being understood that with the parts in 'assembled relation the spring expands and one end thereof fits within thel recess 58, see Figure 2. If desired the pump may be provided with removable plugs 6| positioned adjacent the' respective sleeve assemblies to permit adjustments `of said sleeves, in a manner to be hereinafter described, without disassemblingthe pump.

'I'.he plate 4 8 is secured to a slidably mounted piston 62 which is urged to the right by a spring 64 and is moved to the left against the spring by a rod 88 pivotally connected to one end of a lever 68 having its other end pivotally connected to a link 'III secured to a diaphragm I2 which forms a movable wall between the interior of the pump and a chamber I4 which may be connected to a venturi in the induction passage of a charge forming device, not shown, by means of a passage I6. The effective fuel delivery of the pump is varied by variations in pressure on diaphragm 12' as fully explained in the copending Evans application for a Charge forming device, Serial No. 475,783, filed February 13, 1943. The left end oi.' rod 88 is of a rounded conical shape and is abuttingly received in a rounded conical ldepression in a member 18 secured to the piston 82. This construction facilitates assembly and permitsthe necessary slight rocking .movement of rod 88 upon movement of lever 88. The interior of the housing' of the vpump forms a fuel reservoir 88 which 7 receives fuel from a suitable source through a conduit 82. l

The operation of the pump shown in Figure 1 is as follows, starting with the upper plunger in its extreme right-hand position corresponding to the end of the stroke: Upon rotation of the wobble plate I8, the plunger 24 will move to the left until the annulus 34 passes to the left. of the by-pass sleeve 38. At this time, fuel enters through the annulus 34 and bore 32 to illl the pumping space to the right of the end of plunger 24. Upon movement of the plunger to the right, fuel will be pumped back out of the annulus 34 until it passes into lapped relation with by-pass sleeve 38 which determines the beginning of injection. Further movement of the plunger forces the trapped fuel past a spring loaded check valve 84 into a passage 88, thence to a nozzle supply pipe and nozzle, not shown, which discharges the fuel under high pressure into the engine cylinder. Fuel is discharged from the nozzle until the annulus 36 passes into registry with an annulus 88 vented to the reservoir 88, whereupon the remaining fuel in the cylinder of plunger 24 is pumped into the reservoir 88. This arrangement suddenly relieves the pressure of the fuel being pumped and quickly cuts oir injection, thereby eliminating dripping at the nozzle. Preferably the annulus 38 and the annulus 88 are brought into registry shortly before the end of the stroke of plunger 24v so that the latter portion of the stroke,

which is at a rapidly decreasing plunger velocity o which would produce a decreasing fuel injection pressure, will not be utilized for injecting fuel into the engine. This confines the injection period to the relatively high velocity period of the plunger and the resulting high injection pressure period, whereby better atomization at the nozzle is obtained.

Movement of the by-pass sleeve 38 to the right increases the portion of the stroke during rwhich the annulus 34 is open to the reservoir, or in' other words delays the beginningof injection, and consequently reduces the effective stroke of the plunger. If the by-pass sleeve 38 is moved to its lextreme right-hand position, the annulus 34 does not lap the sleeve 38 at all, or at least not until the annulus 36 isin registry with the annulus 88, and as a consequence no fuel would be injected into the engine; however, if desired a stop may be provided to limit movement of plate 46 and sleeve 38 to the right to thereby determine the minimum effective stroke of the plungers 24. Thus by varying the position of sleeve 38 the eifective pumping capacity of the pump may be varied from zero or any desired minimum value to the maximum capacity of the Dump.

In order to eliminate variations in the quantity of fuel pumped by the individual plungers resulting from variations inthe relative locations of the annuli 34. 38 and l88, and variations in the diameters of the plungers which may occur during manufacturing of same, each of the bypass sleeves 38 is adjustable relative to the plate -48. The adjustment of the sleeves in accordance with the present invention is extremely accurate, and minuteadjustments may be effected.

Bearing in mind that, one of the members 38, 44 has one more notch than the other, as illustrated, it is possible to adjust each of the sleeves 38 laterally relative to the plate 48 in increments equal to the pitch of the thread onl member 38 divided by the product of the number of notches .on said members 38 and 44. Thus, for example,

acess if there are six notches on one member and seven on the other and the pitch of the thread is one thirty-second of an inch, the available' increment of adjustment'is the product of one thirty-#second times one forty-second, or approximately seven ten-thousandths of aninch. To effect the smallest increment oi' adjustment available one portion of the bent end section 58 Vof spring Il, as for example, the curved portion 6l. ismoved out of the respective notch 52 in which it may be positioned by compressing spring fand the sleeve 44 rotated relative to the member l0 and the spring-until said portion 60 of the spring engages the next adjacent notch 52. This effects an adjustment of one seventh of a revolu l tion. Then the other or free end portion "of the section 58 of the spring is lifted up and so moved out of engagement'withthe notch VI2 in which it is receivedvand thedsleeve Il and spring rotated together in the reverse direction until said free end engages the next adjacent notch 42 of member 40. d This effects an adjustment in the opposite direction of one-sixth of Aa revolution and as a consequence the net adjustment is equivalent to the difference between one-sixth and one-seventh, or one forty-second of a revoluas the i'lange on the part; a plurality o'f notches in the ilangeoi the member equally spaced about the periphery thereof; and spring latching means having a portion movable longitudinally relative to the 'device and slidably engageablewwith the notches of said part and said member.

3. The'invention dened bylclaim v2 wherein the spring is coiled about the part between its Iilange and the member and said spring portion includes a curved section; the free end of the end portion being adapted to engage the notches of one ange and the curved section being 'adapted to engage the notches of the other ilange. 4

4. In an adjusting device: an externally threaded sleeve part; an annular flange adjacent one end of the sleeve; a plurality of notches equally d spaced about the periphery of the ilange; an antion. Thus it will be apparent that extremely ilne adjustmentsl may be made with the present invention. However, while the number of,

notches in the respective parts of a sleeve assembly havebeen given as six and seven itis to be understood that any other suitable number of notches may be used in the respective parts,

nular groove in the inner face of the ilange; an annular-ly grooved part threadably received on the sleeve; a reduced end portion of the second mentioned part extending toward the ilange on the sleeve; a plurality of notches4 in the second mentioned part adjacent the reduced end porl tion, said notches being equally spaced aboutthe periphery thereof, there being a different number of notches in said second mentioned part than in the flange of the sleeve part; a spring coiled about the sleeve and reduced end portion and having the coiled ends received in the grooves in the ange and adjacent end of the Esecond mentioned partv and having a bent end section extending longitudinally relative to the axis of the parts, there being an outwardly curved portion as heretofore set forth, it being-understood that the notches of Yeach member, if greater than one, are equally spaced relativeto their `respective members. It is to be further unf erstood that while in the present example one part hasonemore notch than the other said part may have two or three more notches than said other or anyother number that may be 'desired in connection 'with any particular installation. Obviously, the thread may be of any desired pitch.

It is thought that the invention and many of its attendant advantages will be understood from the foregoing description and though said inventtion has been illustrated in connection with but one modification thereof it will be apparent that justable relative to each other; locking .means comprising a coiled spring carried on at least one of said members and having a longitudinally extending end portion; a plurality or circumferentially equally Vspaced recesses on one member engageable with the end'portio'n:` and a plurality of circumferentially equally spaced recesses on the other member also engageable with the end portion, .there being a different number of said equally spaced means on one member than on the other member, said longitudinal portion of in said longitudinally extending'end section of the spring, a portion of the free end oi said longitudinally extending end section being'adapted to be received inthe notches of one of the parts and the outwardly curved portion of said spring be' ing adapted to be-received iii the notches of the other part. l

5. In an adJusting device: having a screw threaded connection and being adjustable relative to each other; a spring carried by the device and having a longitudinally extending end [portion: a plurality of circumfer- `entially equally spaced recesses on one member engageable by the end portion; and a plurality` of circumferentially spaced recesses on the other member also engageable by said end portion; said end portion of the spring being operably movable longitudinally.

- 6. In an adjusting device: a pair of threadably connected members movable relative to each other; an annular flange on one of said members having a plurality of equally shaped notches about the periphery thereof an annular ring on the other member having a flange extending toward the first mentioned flange and having a plurality of equally spaced notches therein; a spring coiled about the device between the flanges and having longitudinally extending end portion including a the locking means being longitudinally movable. c

2. In an adjusting device: an externally threaded part; an annular flange on said part, a plurality of equally spaced notches disposed about the periphery of said ilange; a member-.threadably received on the part; an annular ilange on bent section adjacent one end adapted to be received in the notches of the second mentioned flange, the other end of said end portion being adapted to be slidably received in the notches of the first flange. A l

'1. In an adjusting device: a pair of threadably connected members movable relativev to each other; an annular ilange on one of said members; an annular ilange on the 'other member spaced laterally from same; a plurality of notches substantially equally spaced about the ilanges; and locking means so constructed and arranged as to engage notches in the respective ilanges for mainsaid member of substantially the same diameter 7s taining the members against movement relative ia pair of vmembers on said sleeve and member; engageable means equally spaced en said flanges; there being a different number of said means for one flange than the other; and locking means engageable with the respective engageable means for preventing movement of the parts relative to each other.

9. In a fuel pump for supplying fuel to an enginel comprising: a housing; a plurality of pumping plungers crcularly arranged and spaced apart withinthe housing; an annular channel for each plunger; a passage in each plunger connected with the channel thereof a bypass sleeve slidable on each plunger for controlling the respective annular channels and vadapted to vary the effective stroke of the respective plunger; a member carrying the sleeve; a support for said members; flanges onsaid sleeve and member the circumferences of which are substantially the same; engageable means equally spaced about the periphery of the flanges, there being a different number of means for one flange than the other;

A respective engageable means for preventing moveannular channel thereof adjustable for varying the effective stroke of the plunger; a member carrying the sleeve; a scale for the sleeve having engageable means forming a part thereof and equally spaced apart thereon; a scale for the member of substantially the same length as the scale for the sleeve land having engageable means forming a. part thereof equally spaced apart, the

and resilient locking means engageable with the engageable means o'f one scale being spaced apart `a greater distance than those of the other scale;

resilient locking means disposed between the scales and cooperating with said engageable means for locking the sleeve and member together; an annular groove in the member; and a plate having peripheral notches circumferentially spaced apart in which the groove portions of the members are snugly but rotatably received. said members being held against lateral movement relative to the plate by the respective side walls of the groove. l

l GEORGE P. LUM.

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