US2762654A - Fuel injection device - Google Patents

Description

Sept, 11, 1956 w. J. PuRcHAs, JR.. ET AL v FUEL INJECTION DEVICE Filed July l. 1952 nited States Patent FUEL INJ ECTION DEVTCE William J. Purchas, Jr., and James R. Vickers, Grand Rapids, Mich., assiguors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application July 1, 1952, Serial No. 296,564

7 Claims. (Cl. 299-1072) The present invention relates to devices for injecting fuel into internal combustion engine cylinders and the like, and particularly to improvements in the nozzles of such devices.

One of the principal objects of the invention is to provide an improved fuel injector nozzle wherein the fuel delivery is controlled by a piston type valve operable in response to fuel injection pressure, the fuel being delivered to the nozzle discharge orifices via an internal passage provided in the piston valve, which passage and orices are of registry` except during the period of injection, whereby, fuel injection pressures are reduced, engine fuel consumption is improved, better control of injection timing is obtained and less opportunity exists for engine combustion gasses to leak into the fuel passages of the injection device.

A further important object of the invention is to incorporate with such piston valve an emergencycheck valve means adapted to prevent passage of combustion gasses into the fuel line in the event the piston valve should for any reason fail to close the nozzle orifices.

A still further object of the invention is to provide a nozzlev unit of the aforementioned type comprising relatively few and more simply constructed parts of rugged design adapted for convenient assembly and disassembly.

These and further objects are attained in accordance with our invention by means now to be more particularly described with reference to a preferred illustrative embodiment shown in the attached drawing wherein:

Figure l is a longitudinal sectional View of a combined fuel injector pump and nozzle unit incorporating the principles of the invention.

Figure 2 is an enlarged fragmentary view similar tol Figure l showing the parts of the nozzle assembly in greater detail.

Referring in detail to the drawing, the fuel injector pump unit shown in Figure l includes a housing consisting of an upper body portion 1 whose lower end is externally threaded into a lower nut portion 2 which may be inserted in a suitable opening in the combustion chamber of an internal combustion engine cylinder (not shown). Mounted xedly within the body 1 is a bushing 3 which forms a working cylinder for a reciprocable pump plunger 4 which is urged upwardly against a slidably guided cap 6 by a return spring 7. Opposite ends of the spring 7, as shown, abut a retainer washer 8 which is suitably secured to the plunger 4, and a lower spring seat washer 9 which rests on a shoulder formed by an internal ange 11 of the body 1. Rotatably bearing on a lower shoulder of the flange 11 is a downwardly open cup-shaped plunger rotator 12 whose end wall is apertured to slidably fit a non-circular portion 13 of the plunger. Non-rotatably secured as by a press lit about the cup member 12 is a plate 14 which is loosely retained between the flange 1l and the spring seat 9. One side of the body 1 is slotted to accommodate angular movement of a control arm (not shown) which extends radially from the plate 14 and provides means exteriorly of the body for effecting rotalee tion of the plunger 4. Suitable retaining means in the form of an outwardly expanding snap ring 16 is provided in an internal groove at the upper end of the body 1 for abutment by the cap 6.y

`The interior of the body below the flange 11 forms a fuel chamber 17 which extends around the exterior of the bushing 3, and fuel inlet and outlet connections 18 and 19 are provided in the wall of the body for cornmunication with the upper end of this chamber. Fuel introduced through the connection 18 may thus circulate at all times through the chamber 17 and pass out of the injector unit via the connection 19 for return to the usual transfer pump or other sources of supply (not shown). The plunger 4 has a very close sliding tit in the bore 21 of the bushing 3 and the interior of this bore below the plunger forms a fuel pumping chamber 22. The fuel delivery and relief port 23 provided in the wall of the bushing 3 serves to connect the space 17 with this pumping chamber 22 except when the port 23 is closed by the lower end 24 of the plunger. The outer periphery of this plunger lower end 24 is provided with a relief groove 26 which connects the chamber 22 with an external groove 27 formedfon the plunger just above its lower end 24. The groove 26 extends circumferentially of the plunger between a longitudinal edge 28 and a helical edge 29 whose lower end terminates at the bottom face of the plunger and connects with a short longitudinal edge 31 spaced slightly from the longitudinal edge 28. Lining the body 1 opposite the port 23 is a wear resisting shield 32 which, as shown, is retained in place between the shoulder 33 in the body and an oppositely facing shoulder 34 in the nut 2. Sealing the body and nut against the escape of fuel through the threaded connection 36 from the chamber 17 is a suitable packing 37 in the form of an O-ring type gasket of soft neoprene.

The nut 2 has an opening 38 in its lower end through which extends the lower end of a fuel nozzle 39. The nozzle is enlarged above this opening 38, forming a shoulder 41 which seats on the bottom of a counterbore 42 in the nut 2, and the upper end of the nozzle abuts a spacer washer 43 which in turn abuts the lower end of the bushing 3. The threaded connection 36 of the body to the nut holds the nozzle 39, washer 43 and bushing 3 clamped in stacked end-to-end relation between the bottom of the counterbore 42 and the internal flange 11.

The nozzle 39 is made hollow, having a fuel receiving chamber 44, the lower end of which terminates in a bore 46 which is open at its lower end to the engine combustion chamber (not shown). Reciprocably mounted within the nozzle 39 is a piston valve 47 having an enlarged upper end 48 terminating in an external flange 49 loosely fitting the chamber 44 and a lower stem portion 51 which has a close sliding lit in the bore 46. Between the shoulder 52 at the lower end of the chamber 44 and the piston valve ange 49 is a compression spring 53 which serves to urge the valve 47 upwardly into abutment with the spacer washer 43. Extending longitudinally of the piston valve is an internal fuel passage 54 which is closed at its lower end but is open at its upper end to an enlargement in which is disposed a lighter compression spring 56.' This enlargement in turn opens at its upper end into a further enlargement in which is loosely disposed an emergency check valve in the form of a disc 57 having freedom for limited laxial movement andprovided with one or more notches 53 in its outer periphery. These notches extend radially inward from the periphery of the disk 57 a sufiicient distance to insure communication at all times between the enlargement for the plate 37 and the enlargement for the light spring 56. Pressed into a central recess in the upper end face of the piston valve is a check valve seat 59 having a central opening`61 which is normally closed by the check valve 57 but is open at its upper end to'thepu'mping; c'ha'mberZZL through the central aperture 62I inthespacer washer 43: this aperture 62 constitutes the inlet of the nozzle fuel receiving chamber 44 forv fuel flow from the pumping chatn'ter2-2"l intothe' chamber, and' is' clo'sable by the piston valve flange'L 49` when abutting (as shown) 'the spacer washer 43.

As shown at 63 the enlargement of the-passagef54# which ac'commodatesf the light spring 56 may be chamferdat itss'upper end to provide ample passage for flowl of fuel past the check valve when the check valve is in open position;

The lower end of the fuel delivery passage 54v in the piston valve is closedas`V shown, and aboveits' closed endthewallsr of the stem portion dehning" thispass'ag'e are provide'dwith oneor morewtransverse ports 64 whose outer ends terminate' in an external groove 66v formed on theperiphery ofthe ste'nrportion 511. The lower; end

of-thenozzle 39 is provided withone or more transverseV orifices 67`through which` the fuel is discharged during the injection period but which are normally' out of `registrly with the groove 66 by reason of thev action of the return spring 53' tending to hold the piston valve 47 inl abutment' with the spacer washer 43.

In operation, beginning with the parts-in their positionsas shown in the drawing, fuelintroduced' through the-inlet connection 18 enters the chamber 17 and passes through the port 23 into the pumping chamber 22 below the plunger 4. Asthe plunger is driven downwardly by suitable means (not shown) ythe port' 23 is closed off and the fuel which is compressed in the pumping chamber 22 operates to unseat the check valve 57 .and drive the piston valve 47 downwardly in the nozzle 39. With the check' valve 57 open, fuel within the delivery passage 54 is maintained under pressure and when the piston valve moveswdownwardly a sufficient distance for the groove 66 to register with the orifices 67, fuel is discharged through these orifices 67. Downward movement of the piston valve beyond that necessary' to effect this registry is prevented by the lower end of the enlarged portion 48 moving into abutmentl with the shoulder 52 of the nozzle.

The beginning of fuel pressure build-up in the pump chamber 22 necessary to start injection in the manner described occurs when the bushing port 23 is closed off by the lower end 24 ofthe plunger. In the angular posi-v tion of the plunger, as shown, the pump is set to provide its maximum fuel injection period since the relief groove 2.6 is" out of registry with the port 2,3, and this port remains closed while the plunger travels fromthe position shown until the lower edge. ofthe plunger groove 27 starts to uncover the port 23. A delayed start' of the injection period, together with. a reduction in the duration of the injection period, may be effected by rotating the plunger in the direction of the arrow 71 to cause the closing of the port 23 to be controlled by the helical edge 29. Further rotation of thefplunger in this direction sufficiently to bring the space between the longitudinal edges 28 and 31 of the plunger opposite the port 23 has the effect of cut-ting off all fuel injection, since the-pumpingV chamber22 would then remain in continuous communication with the port 23 via the relief groove 26.

`By reason of the nozzle discharge orifices 67 being closed off by the stem portion 51 from -any fuel delivery through the passage 54 except when sufficient fuel pressure exists above the piston valve to maintain the ports 64 and groove 66 in-registry with these orifices, the start.

and finish of the injection period is much moreV sharp than is the case with previous constructions. Thus, while thesedischarge orifices may be made somewhat larger than is customary (with theresultant` advantage of lowering the injection pressure as pointed out below), no significant quantity ofV fuel is available for afterow or drip at the end of the regular injection period. Also, as will be evident, the positive closing of theseorificesafter eachl injection period resultingf from the withdrawal of It will be recognize/@that v the piston valve stem portion and its close fit in the passage-'54 effectively 'eliminates anypossibility `of air.` o1- cornbustion gases being blown into the fuel chambers 44 and 22 from the engine combustion chamber. The emergency check valve 57 serves also in this respect, by insuring against the high compression and explosion pressures developed in the engine combustion chamber from blowing out the fuel injector with air and combustion gas in the event the piston' valve should for any reason fail to return to its initialA or closed position and .the orifices `67 be left in registry with the groove 66l after completion of the regular injection. period.

During each operatingy cycle the fuel pressures which build up" in the passage 54 and chambers 44' and 22 by the advancement ofthe pumpplunger 4 are relieved as the piston valve uncovers the nozzle orifices 67. This relief of fuel pressure is apparently sufficiently great and quick acting that the biasing spring 53 immediately returnsthe piston val-ve far enough to effect abrief reclo sure of the orifices pending the fuel pressure again being built` upl to causer a re-opening of the orifices. Thus arapid opening and closing of the orifices takes place during theY fuel injection stroke ofthe pump plunger, producing an intermittent fuel discharge The orifice therefore-.may be made"I larger than would otherwise be the case-where thefuel dischargewas steady, thereby reducing the'. fuel; injection pressure. Also, apparently on account of the fuel being ydischargedy intermittently, a better interrnixture of the fuel with the combustion air supply'iswobtain'ed. which is reflected in an improved' fuell economy ofenginesincorporating our invention.

Itwill' be'iobs'erved thatthe nozzle. 39, piston valve 47,

check valve 57,'` seat.59y andY springs 53 are all of simple for fuel delivered underl pressure to the nozzle, said bore.

having a' fuel discharge orifice adjacent its open end, a piston valve slidably fitting said bore and provided with an' enlargement extending into said chamber, said valve having a passage fori conducting fuel from said chamber tovsaid orifice, resilient means within said chamber and interposed between: said nozzle' and valve enlargement tending vto-withdraw the valve'into the chamber from said bore and thereby maintainy said passage out of registry with said orifice, said resilient means being yieldable to accommodate movement of the valve farther into the bore inresponseto a predetermined fuel pressure in said chamber to effect registry of sai-d passage with saidV orifice, and a check valve associated with said passage to prevent reverse flow therethrough from said orifice to said chamber when said passage is in registry withsaid orifice, said passage-being imperforate between said orifice and check valve.

2. In a fuel injection device, a fuel pump including ay plunger anda pumping chamber for said plunger, and: means includingv a nozzle through which the fuel is passedV said'orifice, anda one-Way valve controlling the entrance v to said passage from the chamber, said one-way valve being operable to open position in response to fuel pressure in said chamber and operableto closed position in response to externalfiuid pressure transmitted through said orificeV and passage/ while in connected relation.

-3. In af -fuel injection device, a fuel pump having a pumping chamber, a fuel nozzle having a chamber arranged to receive fuel under pressure from the pumping chamber and an open ended bore leading from said nozzle chamber having a side discharge orifice, a piston valve slidably reciprocable in said bore and movable toward said bore open end in response to fuel pressure in said nozzle chamber, a spring interconnecting said nozzle and piston valve tending to move the piston valve in the opposite direction, said piston valve having an internal passage extending longitudinally thereof and closed at its end nearest said open end of the bore, stop means on the nozzle limiting movement of the piston valve against said spring, a normally closed check valve controlling the opposite end of said passage and carried by the piston valve, said check valve being operable to open in response to fuel pressure in said chambers, said piston valve having a transverse port extending from said passage to the periphery of the piston valve and located for registry with said orifice when the piston valve is engaged with said stop means.

4. A fuel injection device comprising a housing having inlet and outlet fuel connections, a bushing within the housing forming a fuel pumping chamber and having an opening in its wall connecting said pumping chamber to said connections, a pump plunger reciprocably slidable in said bushing and controlling said opening, a nozzle seated in the housing opposite the plunger having a chamber portion forming an extension of said pumping chamber and a bore of smaller cross-sectional area leading to the exterior of the housing from said chamber portion, said bore having a fuel spray orifice in the wall thereof exteriorly of the housing, a piston valve reciprocable in the nozzle having a stem portion closely fitting said bore and enlarged portion loosely fitting said chamber portion, said piston valve having a longitudinal passage open to the chamber port-ion at its end adjacent thereto and closed at its end remote from said chamber portion and a transverse port adjacent the closed end of said passage, spring means within said chamber portion and normally holding the enlarged portion of said piston valve in operatively abutting relation with the adjacent end of said bushing in which relation said port is out of registry with said orifice, said enlarged portion forming a shoulder at its juncture with said stem portion, said piston valve being movable against said spring means in response to fuel pressure in said pumping chamber and chamber portion to effect registry of said transverse port and orifice, said shoulder being engageable with the wall of said chamber portion adjacent said bore during said piston valve movement to limit said movement to that necessary to effect said registry.

5. In a fuel injection device, a nozzle having a bore open at one end and terminating at its other end in a fuel receiving chamber of substantially larger cross-sectional area than said bore, said bore having a fuel discharge orifice in the side thereof adjacent its open end, and a piston valve slidably fitting said bore and extending into said chamber, said valve having a one-way valve controlled passage for conducting fuel from said chamber to said orifice, a check valve carried by the piston valve preventing fluid iiow into said chamber from said passage, resilient means in said chamber and interposed between said nozzle and piston valve tending to withdraw the valve into the chamber from said bore and thereby maintain said passage out of registry with said orifice, and means for introducing fuel under pressure to the chamber to cause said piston valve to move farther into the bore against said resilient means and effect registry of said passage with said orifice.

6. In a fuel injection device, a nozzle having a bore open at one end and terminating at its other end in a fuel receiving chamber, said bore having a fuel discharge orifice in the side thereof adjacent its open end, and a piston valve slidably fitting said bore and extending into said chamber, said valve having a passage for conducting fuel from said chamber to said orice, a check valve carried by the piston valve preventing fluid flow into said chamber from said passage, said passage terminating at its end nearest said chamber in a series of three enlargements of relatively increasing size, each forming a shoulder at its end opposite said chamber, a valve seat closely fitting the largest of said enlargements and engaging the shoulder thereof, said check valve being disposed in the intermediate enlargement and having freedom of movement between the shoulder of said intermediate enlargement and said seat, a check valve spring disposed in the smallest of said enlargements and acting against the shoulder thereof and the check valve to normally hold said check valve in closing relation with said seat, and resilient means interposed between said nozzle and piston valve tending to withdraw the piston valve into the chamber from said bore and thereby maintain said passage out of registry with said orifice.

7. In a fuel injection device, a nozzle having a bore open at one end and terminating at its other end in an enlargement of said bore defining a receiving chamber for fuel delivered under pressure to the nozzle, said chamber having an inlet, said bore having a fuel discharge orifice adjacent its open end, a piston valve slidably fitting said bore and provided with an enlargement extending into said chamber and normally closing said inlet, said valve having a passage for conducting fuel from said chamber to said orifice, resilient means Wi-thin said chamber and interposed between said nozzle and valve enlargement tending to Withdraw the valve into the chamber from said bore to effect closure of said inlet and maintain said passage out of registry with said orifice, said resilient means being yieldable to accommodate movement of the valve farther into the bore in response to a predetermined fuel pressure in said chamber to effect opening of said inlet and registry of said passage with said orifice, and a check valve associated with said passage to prevent reverse flow therethrough from said orifice to said chamber when said passage is in registry with said orifice, said passage being imperforate between said orifice and check valve.

References Cited in the le of this patent UNITED STATES PATENTS 1,893,457 Tortrais Jan. 3, 1933 2,272,094 Murphy Feb. 3, 1942 2,291,218 Hefter July 28, 1942 2,408,288 Bremser Sept. 24, 1946 2,571,501 Truxell Oct. 16, 1951 2,628,866 Purchas et al. Feb. 17, 1953 FOREIGN PATENTS 610,873 Great Britain Oct. 21, 1948 925,343 France Mar. 24, 1947

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