US2628866A - Fuel injection pump - Google Patents

Description

Feb- 17, 1953 w. J. PURcHAs, JR., ETAL 2,628,356

FUEL. INJECTION PUMP l Filed April 25, 1950 Snnentow Patented Feb. 17, 1953 vFUEL INJECTION PUMP William J. Purchas, Jr., and Clyde W. Truxell, Jr., Grand Rapids, Mich., assignors to `General Motors Corporation, Detroit, Mich., a corporation of Delaware Application April 25, 1950, Serial No. 157,922

The present invention relates to fuel supply means for internal combustion engines and more particularly to fuel injection pumps for controlling and effecting the delivery of fuel under pressure to the cylinders of a solid fuel injection engine.

It is an object of the present invention to provide an improved fuel injection pump of sim plied construction.

`lt is a further object of the present inventionv to provide a fuel injection pump so constructed and arranged to substantially reduce untimely fuel injection caused by fuel surging within the injector structure.

These and other objects are attained in accordance with the present invention byproviding a fuel injection pump in which fuel injection is controlled by an improved multiple valve arrangement which substantially reduces fuel injection causedby fuel pressures in the internal chambers resulting from surging of the confined fuel.

For a better understanding of the invention, reference may be had to the drawing in which Figure 1 is an elevational view partly in section and partly broken away of the fuel injection pump ofthe present invention; Figure 2 is a view taken on the line 2 2 of Figure 1 with parts broken away and parts in section.

Referring now to the drawing there is illustrated the fuel injection pump of the present invention comprising a shell or casing 2 formed of an injector body portion 4 and an injector nut `portion 6 vsecured together in threaded engagement at 6 with a sealing ring I6 of suitable material, such as neoprene clamped therebetween to-provide a sealed joint. Within the injector n ut portion 6 and at its lower end there is disposed a nozzle or spray tip I2 formed with a central passage I4 terminating at Iits upper end in an enlarged passage I6 and provided with radially disposed transverse passages I8. Seated at the upper end of the nozzle or spray tip I2 there is an injector valve assembly 26 consisting of a bushing 2-2 having a Vcentral passage 24 enlarged at its upper end. as shown. Disposed in the passage is a valve 26 provided with an enlarged head 28 with a conical seating surface 30 adapted to engage the'valve seat 32 of the bushing 22. The valve is yieldingly urged to its closed position on seat32 by the helical spring 34 which surrounds the stem of the valve 26` with one end recessed in the enlarged upper end of passage 24 and the other end in engagement with a C-washer 36, slidably secured to the stem of thevalve 26. A valve spring cage 38 having a passage 40 with 1 Claim. (Cl. 299-1072) upper and lower enlarged portions is disposed within the injector vnut adjacent to the valve assembly with the stem of the valve 26, spring 34 and C-washer 36 recessed in the lower enlarged portion of passage 40. With the valve assembly .2U disposed adjacent the nozzle or spray tip I2 the enlarged head 28 is recessed in th-e enlarged passage I6 of the nozzle or spray tip I2. To avoid complete stoppageV of fuel flow fro-m passage 24of bushing 22 to passage I4 of the nozzle or spray tip I2 because of breakage of spring 34, C-washer 36 or the stem of Valve 26 permitting the valve to fall by gravity to close passage i4, the enlarged head 28 is provided with a transverse slot 42 which will permit fuel flow to passage I4 should the valve become inoperative by breakage of one of the hereinbefore mentioned valve parts. Positioned at the upper end of valve spring cage 38 is a second valve assembly 44 and valve spring cage 46 such as described in connection with valve assembly 20 and valve spring cage 38j.

Disposed within the casing .2 there is a cylindrical bushing 4B provided with a central passage 50 in communication with an annular space 52 surrounding the bushing by means of a passage 54 through the wall of the bushing. The lower end of the bushing 48 is seated on the upper end of valvecage 46 with the bushing passage 50 and the central passage of the valve spring cage 46 in communication. The bushing is formed Vwith a reduced end 56 which passes through aninw'ardly extending ange 58 formed integral with the injector body portion 4. 'Oppositely disposed flatsurfaces 6Il formed on the flange walls, see Figure 2, cooperate with similar at surfaces 62 on the reduced end 56 of bushing 46 to prevent the rotation of the bushing within the casing. As shown, a shoulder 64 formed at the junction ofthe body of bushing 48 and its reduced upper end 56 seats on the lower side of the inwardly extending flange 53; thus with the bushing 48. valve assemblies 2!) and 44,

valve spring cages 38 and 46 and nozzle or spray tip I2 assembled, as shown, they are clamped end-to-end as the injector nut 6 is threaded on the injector body 4. An annular oil groove 66 is formed in the wall of passage 50 at substantially the upper end of bushing 46 and is connected with annular space 52 by a passage 66 through the wall of the bushing. To prevent surging fuel within the annular space from eroding the inner walls of the injector body 4 and injector nut 6, a cylindrical dei-lector 66 of suitable hard material is loosely positioned within the casing, as shown. 1

Reciprocably mounted within the bushing 48 there is a piston or plunger 10. Adjacent the lower end of the plunger there is provided an annular groove '|2 which is in communication with chamber 50 in bushing 48 through a longitudinally extending slot 14. The longitudinal slot '14 terminates ing-f'a r"recess '16 formed 2in ',the wall of the piston lalt itsvlowerend withone side wall |-8 of the recess 1B extending helically and circumferentially around the piston, as shown. The upper end of the piston 10 is formed withan enlarged head 80 and an enlarged portion v82. The head 80 of piston 10 is're'cessed-in"ani'upper spring seat 84 which is yieldinglyiirgedlup-wardl-y by a helical spring 86. Thellower end loflspring 86 is seated on a lower spring seat 88 which in turn is seated on an annular shoulder iflorrned in the inner wall of the injector body portion 4. The lower spring seat 88 is provided "with la longitudinally extending slot 92, see Figure 2, iwhich receives Ethe `end -of a -pin 94 :passing A.through )the walll of the i injector body Aportion t -to'preventrotation 'of the lower yspring seat .in .the Y.injector body portion v4.

iRotatabl'y mounted onthe uppersurface' ofthe `inwardly extending :flangez `58 -is afcontrolassembly i961 comprising alsleeve -98andfa control arm |00,isee yFigure 2, attached-tothe sleeve `at |52 :by suitable? means suchfaswelding. -The control arm-|001extends througha slot |04 in the vwall :of the `injector body portion S4' extending Acircum- :ferentially around-the bo'd'y portion to permit an Aangular movement ofthe 'control arm and :sleeve through :substantially 90 degrees. The' sleeve 98 receives the upper yportion 'of the redueedr'end I5|5-`=of -hushing-L'4-8'Which lextends above lthein` lv/ardlyv extending 'flange .'58 "and is provided with '=a centralpassage |06 through lthe end thereof through which theplunger i`| 0 passes `to*` permit :'reciprocation of the plunger.

tation'V or the plunger 'andcontrol of the quantity of fuel forced from the fuel purnp injector ina manner xi/hichvill be described hereinafter,'the passage |06 'has a hat wall portion," not shown, Iwhich is 'adapted to :engage a cooperating fflat l-surface portion |08 on the enlarged-portion Aft2 of: the plunger. 'Such aiV construction permits recipi-ocaticnnof theplunger in the'sleeve but're- :stricts f rotary vrnovenle'nt i of 'Y the plunger to the langular movement of the=c`ontrol assembly Tin A1:1ge'irieraliyxv C-'shaped clamping spr-ing H52 recessedinan annulangroove! Efein'ftlie inner wall f the'llody andad'j'acet-ts upper end retains fthe -ffoilowersleeve' in 'the *bdy with fthe annularspace`52 receive theffuel inlet 'do'tlet fttingslf and |22^bth of which are adapted to removably 'contain lter elements |24, as shown.

L'Ilie assembled injector is ntted intoa passage `-|26Vv inthe vcylinder block of 'a solidfuel injection 'engine '|28 w'ith'the passagelZE formed'with a well 'configuration conforming to the external Wall contourV of the injector .nut portion e there 'by providing'a seat for the injector on the engine head with the nozzle or spray tip I2 exposed in rthe combustion space |3|of-the.eylinder. A yoke having arms' |30 engaging the shoulder |32in-thc outer Wall f'the injector body is attached `to Tof provide for roalle l to* the they spring ofthe u-pp Any well known means such as a rocker arm and 1-p'ush rod engaging a cam on the camshaft of the -engine-may be used to effect a downward move- 'inentpf the follower ||0 and the plunger 10. `Witlrifuelfcirculating in the annular space 52 and iillingthe pumping chamber 50, the recess 16 and *annular l'groove* '12 on the plunger 10. a

downwardstrke of the plunger closes the pasfsaged and forceslfuel entrapped in the pumping chamber 50 under high pressure past the upper and --lower valves and out of the orices I8 and into the combustion space |3| in the form of `iinely divided spray. In this'connection itftwill be 'fobvious `that vthe :angular Mposition of the A.plunger 10 and the circumferentially .extending helical `iside 'Wall f''S-iof i the frecess *|16 determines y'the positionofethe'piunger in theLpumping `chamber at which the passage 5A is closed to the pumping chamber. V`With fthe 'control :assembly and plunger `in substantially the1positions-as1showm passage 54 is closed as theienii'ofthexplunger passes vthe-lower 'edge-:oi 'thepassage .In this .l position 'maximum 'volume of i. fuel will be en- 'tr'appe'd in the purnping f. chamber land will :be roi-ced :out off'the'injector bytheA downwardmovement of the plunger. With theplungerlandicontrolaassembly "rotated, the circumferentially sex- 'tenn-ing .helical :sidewall 4il! fofvrecessif'l si is placed 'position tofclose the passage lidxat :a consid- -erablylgreater depth-ioftheplungerfin thelpurnping ichairiben. thusforcinga :smaller quantity of fomhthe injector. fnsitlie plunger continues its ffiiow'nivard Sst'r'o'lielin any of 'itsirotated i posi tions in the bushing, the groove 72 opener-into tneapassageffd andi fueisfromltiie pumping' cham- -b'er is passed`throug'h' the longitudinallyextend- Fiil whichlaiisibytheegroovef'|52 arid along the iside wally df fthe tplunger vil -is 'entrapped'in the oil groove Band'dra'instliroug'h passage l031:0 Ktlielainiularspace 52.

Lvplacing'Uthe tv/o cheek vvalve'a'sse'iriblies 20 with'` likejsp'iingtensions'in lseries in the outlc passages froin"the'pumping 'chamber -50 oz'zleforsprayftip lT2; double the pressure isfre .iire'clinthe pumping chamber to'open the valveagainstl 'its biasing spring than would t tofcpe'n the-:upper-valve against its spring 'tension-for f-'a *single l'valve between the pumping 'chamber and 'the nozzle'. As 4the 'plunger-I0 @moves 'do Yiwardly'in" the entrapped fiiel 'pumping' c-v flthe pressurel in"l the -pumpingf'cha-mber 1 reases-fu'ntilthe'tension oi valve is' overcome thus iilling th'epass'age lw h'ffuelu-nder'the pressure o.:ci he j uel in,l pumping chamber "50. `"Ihe'press ref the-fuelfin passage "50 'actsnpwardl'y closing 'spring toireoiireiin@pumping chamber `5'0 a fuel'pressure"substantially'two' times the lpreslower valve substantially near the outlet orifices, optimum operating characteristics are provided.

With the two valves in series in the outlet passage a suiciently high pressure is required for ejection of the fuel that pressures built up in the pumping chamber and connected passages due to surging of the fuel during the movements of the plunge;` in the bushing are not suficient to open the valves and prematurely eject fuel to the combustion chamber ISL Further, with the lower valve placed substantially near the orifices I8, air or combustion gases which may become entrapped in the passages of the nozzle l2 by the movement of the piston are reduced to a minimum thus maintaining fuel to air ratios which are substantially constant.

What we claim as new and desire to secure by Letters Patent of the United States is:

In a fuel injection pump, a casing comprising upper and lower hollow members having their adjacent ends in telescoping interthreaded engagement, said upper member having an internal flange forming a lower fuel receiving chamber and an upper spring chamber, said flange having an opening connecting said chambers, said opening having a flat side, a cylindrical bushing disposed longitudinally within said casing having a reduced diameter upper portion with a flat side fitting said opening and a lower portion of larger diameter in abutment with the underside of 'said flange, a plunger slidably litting the bore of said bushing and extending from the upper end thereof into said spring chamber, a spring retainer secured to the upper end of said plunger, a helical spring compressed between said retainer and said flange, a follower of inverted cup shape enclosing the retainer and guided for reciprocation therewith by the side walls of said spring charnber, said plunger having an elongated dat sided portion embraced by said spring, an inverted cupshaped sleeve having a flat sided aperture in its end wall slidably fitting said plunger portion, a control arm secured to said sleeve and passing through the side wall of said upper member, said upper member being provided with an elongated slot accommodating rotation of said arm to effect angular adjustment of said plunger about the axis of said bushing, said bushing lower portion forming a fuel pumping chamber below said plunger and provided with a plunger controlled port in the bushing wall through which fuel may enter said pumping chamber from said fuel receiving chamber when the plunger is retracted by said spring, said upper member having fuel inlet and outlet connections communicating with said fuel receiving chamber, said lower member having an internal shoulder dening the lower limit of said fuel receiving chamber and a passage extending therefrom through the lower end of said lower member, said central passage having an internal shoulder adjacent its lower end, a fuel nozzle fitting the lower end of said passage and retained by said shoulder, said nozzle having a longitudinal fuel duct of restricted capacity terminating at its upper end in an enlargement, a check valve assembly in said passage comprising a downwardly opening check valve having a head loosel,7 received in said enlargement with a stem extending upwardly in said passage, a valve seat resting on said nozzle and having a longitudinal duct embracing the valve stem with only suiicient clearance to accommodate required fuel flow during pump operation, a spacer resting on said seat and having a downwardly open recess in its lower end forming an enclosure for said valve stem, resilient valve closing means substantially filling the space between said stem and the interior surfaces of said recess, said spacer having a longitudinal fuel duct communicating with said recess and terminating at its upper end in an enlargement, a second check valve assembly in said passage identical to said first named assembly having its valve head loosely received in said spacer enlargement and its valve seat resting on said spacer, a second spacer in said passage identical to said first named spacer and resting on the valve seat of said second check valve assembly, said valve seats and spacers having a close iit throughout their length with the walls of said passage and being clamped in stacked end-to-end abutting relation between said nozzle and said bushing by the interthreaded engagement of said upper and lower members.

VVILLIMl J. PURCHAS, JR. CLYDE W. TRUXELL, JR.

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

UNITED STATES PATENTS Number Name Date 2,014,088 Nicolas Sept. 10, 1935 2,313,264 Reggio Mar. 9, 1943 2,378,165 Waeber June 12, 1945 2,521,224 Kammer Sept. 5, 1950 FOREIGN PATENTS Number Country Date 57,343 Norway Dec. 14, 1936

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