US2573344A - Fuel injector - Google Patents

Description

E. P; LARSH FUEL INJECTOR Oct. 30, 1951 Filed Sept. 13, 1946 :Elf

INVENTOR. ,.Mazivud N .I S

Patented ct. 30, 1951 UNITED STATES PATENT OFFICE FUEL INJECTOR Everett P. Larsh, Dayton, Ohio Application September 13, 1946, Serial No. 696,855

(Cl. S- 41) 11 Claims.

This invention relates to a vfuel injector and is designed primarily for delivering measured quantities of fuel under high pressure to a diesel engine. y Y Y One object of the invention is to provide a fuel injector of improved construction and operation which canvbev produced at a relatively low cost and whichA can be easily assembled and disassembled.

A further object of the invention is to provide a fuel injector comprising a barrel and a plunger of simple` easily 'manufactured constructions and whichV will positively and` accurately meter-the fuel in accordance with the requirements of the engine.

A further objectvof the invention is to provide a fuel injector in which the check valve for the fuel outlet is so connected with the barrel that it may be inserted in and removed from they housing of the'injector along with the barrel.

Other objects of the invention may appear as the injector is described in detail.

In the accompanying drawings Fig. 1 is a longif tudinal section taken centrally through an injector embodying 'the invention; Fig. 2 is a transverse section takenon the line 2-2 of Fig. 1; Fig. 3 is a transverse section taken on the line 34-3 of Fig. 1; Fig. 4 is a side elevation of the barrel and check valve assembly; Fig. 5 is a longitudinal section taken centrally through the barrel; and Fig. 6 is a transverse sectionl taken through the barrel on the line 6 6 of Fig. 5.

In these drawings I have illustrated one embodiment of 4the invention and have shown the same in a form adapted for installation in a multi-cylinder diesel engine in which a separate injector is provided for each cylinder, but it is to be understood that the injector as a Whole, as well as the several parts thereof, may take various forms and may be installed in engines of various kinds without departing from the spirit of the invention.

In the embodiment here illustrated the injector comprises a housing I0 having within the same a longitudinalchamber Il which is cylindrical in form but is of different diameters in different parts vof the housing. The housing is preferably formed in one piece fromv a block of steel which may have any suitable exterior form and is `here shown as substantially square in cross section. The chamber I-I terminates at a point spaced a short distance from the forward end of the housing, Aand the endwall ofthe housing is provided with.,V fuel ldelivery 0conduits I2 i which are connetedwithzan. @percing-.I3 which communicates 2 n with the chamber II. These conduits "are adapted to be connected with the combustion chamber in a cylinder of a diesel engine, and the number of conduits will, of course, correspond to the number of injector nozzles in the cylinder.

Mounted in the housing is a barrel I4 which is preferably cylindrical in Yforrn and which has therein a longitudinal bore I5 which constitutes a pump cylinder. The forward end of the bore communicates with a fuel outlet I6, of reduced diameter, which in turn communicates with the opening I3 leading to the fuel conduits I2', as hereinafter described. .The barrel is also pro#- vided withone or more fuelinlets spaced rearwardly from the outlet end of the bore and .here shown as comprising'lfour. radial ports I'I arrangedrin a common plane and connected'at their inner ends Ywith the bore I5 and at their outer ends with an inlet fuel chamber. `The inlet chamber may be of any suitable character; but preferably it i's in the nature of an annular recess I8 formed in the inner surface of the housing and extending about the inlet ports and for some distance to'the :rear'of' said ports. The inlet chamber is connected with a fuel supply conduit I9, adapted to be connected with a fuel supply pump inthe usual manner, and witha discharge conduit 25) adapted to return excess fuel to the source of supply. Means are pro'- vided for maintaining the fuel in the inlet chantber I8 at a pressure suflicient to cause the same to quickly enter the bore of thebarrel when the ports I'I are'o'pened. This 'may be accomplished invarious ways,` and in the present instance the discharge conduitr23` is ofsmaller diameter than the -inlet conduit I9; The flow of fuel oil through the inlet chamber also serves `to cool the'barrel.

Mounted for Areciprocatory movement in the bore I 5 is a plungerZl which extends rearwardly beyond the barrel for connection with an actu.- ating device and is ofsuch length that when it is in its retracted position the forward end there? of will be' atthe rear offbutllclose `to the inlet ports'v I'I, so that the initial forward movement-of the plunger kwill ,close theginlet ports and thereby trap fuel in the forward;portion 22jof the bore and subject the fuel therein to -high pressure to force the same through the outlet I6 and -through the delivery conduitsgjIZ- to Lthe cylinder of the engine, the part 22 of the bore thus `constituting a pressure chamber. The plunger is moved forwardly a predetermined constant distance upon each operationthvereof. and thev fuel delivered to the engine is metered-,byrelievingv the ypressure' thereon innthepressure :chamberiwhen thedesired quantity of fuel has been discharged from the latter, it being, of course, understood that the delivery conduits are maintained full of fuel at all times during the operation of the injector and that the amount of fuel entering the cylinder will correspond exactly to the amount discharged from 'the pressure chamber.

The plunger2i is mounted for movement about a longitudinal axis, as well as for reciprocatory movement, and has in its forward portion a small diameter passage 23 which extends rearwardly from the forward end thereof and is connected with the exterior of the plunger by a lateral port 24. The barrel I4 has formed therein a vent through which the fuel in the passage 2,3 may es-V cape when the port 24 is moved into communication with the vent, thereby relieving the pressure in the pressure chamber and preventing the discharge of fuel therefrom by the further forward movement of the plunger. obliquely to the bore I5 and is here shown as a straight slot 25, of narrow width, which commuf nicates with both the bore I5 and the inlet chamber I8. The slot is yhere shown as a straight saw cut through approximately one half the barrel, which is adapted to communicate at all times with the inlet chamber but is normally closed at its inner side by the plunger. The slot, or at least the major portion thereof, lies in front of the port 24 `in the plunger when the latter is in its retracted position. When the plunger has moved forwardly a distance determined by its rotary position with relation to the bore the port will be brought into communication with the slot and the pressure within the pressure chamber will be instantly re lieved. Due to the oblique arrangement of the slot the rotary adjustment of the plunger positions the port 24 different distances from the slot. It is shown in Fig. 1 as: midway between the upper and lower portions of the bore. If the plunger is rotated to move the port toward the upper side of the bore, the distance between the Aport and the slot 25 will be correspondingly increased, and if the port is moved toward the lower side of the bore the distance between the same and the slot will be decreased. Thus the rotary position of the plunger determines the extent to which the plunger Awill enter the compression chamber before the pressure is relieved, although there is a constant stroke of the plunger, and thus determines the amount of fuel which is discharged from the pressure chamber. To maintain the vent open in the event the port moves entirely beyond the vent the port is provided with a rearward extension. here shown as a groove 26 in the outer surface of the plunger.

The barrel may be mounted in the housing and retained therein in any suitable manner. In the present instance there is connected with the forward end of the barrel a check valve assembly, to be hereinafter described, which forms in effect a continuation of the barrel and which abuts against a disk 21 of copper, or other suitable material, Vin the forward end of the chamber I I and is provided with an opening in line with the opening I3 which leads to the delivery conduits. The rear edge of the large diameter portion of the barrel is chamfered for engagement with a correspondingly shaped annular member or ring 28, of copper or the like, which ts within the housing and is clamped tightly against the barrel by an annular nut 29 having threaded engagement with the housing, a ring or spacer 30 being preferably interposed between the nut and the chamfered ring l28. Thus the tightening fof the This vent is arranged nut clamps the barrel tightly between the ring 28 and the disk 21 at the forward end of the housing and tightly seals the connections between the barrel and the housing. If desired, a set screw 3I may extend through the wall of the housing into a short slot 32 in the barrel to hold the latter against rotation and retain the slot 25 in a predetermined position. To prevent the barrel from being distorted by pressure to which it may be subjected a rigid spacer is preferably interposed between the side walls of the slot 25 adjacent the center of the latter. This may be easily accomplished by welding the outer edge portions of the Walls one to the other, as shown at 33, the weld being spaced such a distance from the bore I5 that it does not in any way restrict the communication between the slot 25 and the bore. The barrel may be removed from the housing by removing the nut 29, and to facilitate the removal of the barrel it is preferably provided with a rearwardly extending small diameter portion :i4 having a screw threaded rear end to engage a threaded socket on a rod or other implement by which the barrel may be withdrawn.

To facilitate the insertion and removal of the check valve 35, which is interposed between the pressure chamber and the delivery conduits to prevent the reverse flow of fuel when the plunger moves rearwardly, the check valve is so connected with the barrel that it may be inserted and removed along with the latter, and for this pur-.- pose there is provided a Vcheck. valve assembly which is attached to the forward end of the barrel. In the arrangement here shown the assembly includes a disk-like body member 36 supported in line with the barrel and in which the outlet I6 is formed. Interposed between the body member 36 and the end of the barrel is a disk 31 having therein an opening 3B which is in open communication with the bore I5 of the barrel and is in line with the outlet I6, and in effect forms a part of the outlet. The b'ody member 36 is provided at ythe inner end of the outlet opening I6 with a shallow cylindrical recess 39 which faces the disk 3l, and the valve 35 is mounted in this recess. As shown more particularly in Fig. 2 the check valve 35 is of the clover leaf type and is accurately centered with relation to the outlet openings I6 and 38 by the contact of the lobes thereof with the cylindrical wall o f the recess 39, the recess being of such depth that the valve can move to its open position to permit the fuel to iiow through the lopening 38 about the check valve to the opening I6. The body member 36 may be attached to the barrel in any suitable manner, but in the present instance the adjacent portions of the body member and the barrel are o1' a diameter slightly less than the diameter of thechamber II in the housing and are provided respectively with circumferential recesses 40 and 4I. A ring 42 of metal or the like extends about the adjacent portions of the two members of the valve and the lateral edges thereof are bent into the recesses 40 and 4I, thus rigidly but detachably connecting the end member with the body member of the barrel.

Reciprocatory movement may be imparted to the plunger in various ways, but this is usually accomplished by a cam capable of subjecting the fuel in the pressure chamber to very high pres` sures. In the arrangement here shown the cham ber I I of the housing extends rearwardly beyond the barrel, and the rear portion thereof is of a' slightlyvlarger diameter than the front por-tion' thereof- V',llid'ably vmounted in 'this rear 'portion of the housing is a follower or tappet 43 which is here shown as cup shaped with the closed end thereof adjacent the rear end of the housing. The plunger extends rearwardly into this cup shaped follower and is provided with a reduced portion or neck 44 which extends through and is rotatable in an opening 45 in a member 46 supported in the follower. The rear end of the plunger may be of the same size as, or larger than, the body portion thereof and thus constitutes a head 4l which is seated in a recess 48 in the rear side of the member 46 and is thus held firmly between the member 46 and the end wall of the follower, so that the plunger moves longitudinally with the follower. A spring 49 is confined between the member 48 and an annular member i! which in the present instance is supported against a shoulder 5I within the housing and serves to move the follower and plunger rearwardly, the housing being provided with one or more breathers 5ta. The closed end of the follower 43 is provided with a recess 52 and has mounted therein a short shaft or pin 53 which extends through the recess and which rotatably supports a roller 54 in the recess. The shaft 53 preferably extends into grooves 60 in the housing to prevent movement of the follower and shaft about a longitudinal axis. The roller extends slightly beyond the rear end of the follower and is engaged by a rotary cam 55 to impart forward movement to the follower and to the plunger.

The movement of the plunger about its longitudinal axis is controlled in accordance with the fuel requirements or speed of the engine, this being usually accomplished by the use of a suitable governor. 'Ihe governor itself forms no part of the present invention, but the governing mechanism includes a rack bar 56 which extends transversely to and is slidably mounted in the housing I0. Meshing with the rack bar 55 is a gear 5l, l

so mounted on the plunger 2l that the plunger will rotate with the gear but will be capable of axial movement with relation thereto. As here shown the rear portion of the plunger is provided with a flat 58 on one side thereof and the gear is provided with a correspondingly shaped opening through which the iiattened portion of the plunger extends. Thus the rotary position of the plunger is controlled by the governor, and the port 24 in the plunger is moved laterally in one direction or the other to space the same different distances from the vent or slot, according to the fuel requirements, and the extent to which the plunger enters the pressure chamber before the pressure in the latter is relieved is so controlled that the fuel delivered to the engine will be very accurately metered. It is to be understood, of course, that the rotary adjustment of" the plunger may be and usually is effected simultaneously with the longitudinal movement thereof.

While I have shown and describedr one embodiment of my invention, I wish it'to be understood that I do not desire to be limited to the details thereof as various modifications may occur to a person skilled in the art.

Having now fully described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. A fuel injector comprising a barrel having a longitudinal bore, a fuel outlet adjacent the forward end of said bore and a fuel inlet spaced rearwardly from said outlet, said barrel also having an elongate pressure relieving vent extending through the wall thereof in the rear of said fuel 6. inletifand e'xtendingat anacu'te angleto said bore, and :a lplunger mounted in said bore for forward Vmovement therein to close said inlet and exert'pressure on the fuel in said bore 4between said inlet and said outlet, said `plunger having a passage extending rearwardly from the forward end ythereofand also having a lateral port communicatingwith the rear portion of said passage and arranged to be moved into communication with said pressure relieving vent by the forward movementof said plunger, said plunger being. adjustableabout a longitudinal axis.

-\2. Afuel injector comprising a barrel having allongitudinal'bore, :a fuel outlet adjacent the forwardY .end of said bore and a fuel inlet spaced rearwardly from said outlet, said barrel also having arelativelynarrow slot extendingin a straightline oblique to.said bore through: the inner and outer surfaces of said barrel, and a plungerlmountedin said .bore for reciprocatory movement into. and out of the forward end portion of :said bore andfor movement about a longitudinal axis, said plunger having a passage extending rearwardly from the forward end thereof and also having a small diameter opening communicating with said passage inthe rear of said slot and. arranged to be moved into communication with said slot by the forward movement of said plunger.

3. A fuel injector comprising a barrel having a longitudinal bore, a fuel outlet adjacent the forward end of said bore and a fuel inlet spaced rearwardly from said outlet, said barrel also having a relativelynarrow slot extending in a straight line. oblique to said bore through the inner V and Vouter surfaces of said barrel, `and a plunger mounted in said bore for reciprocatory movement into and out of the forward end portion of said bore and for movement about a longitudinal axis, said plungerv having a passage extending rearwardly from the forward end thereof and a small diameter opening communicating with said passage inthe rear of said slot and arranged to be moved into communication with said slot by the forward movement of said plunger, said plunger also having a groove in the exterior surface thereof communicating with and extending rearwardly from said opening. 4. A fuel injector comprising a cylindrical barrel having an axial bore, a fuel outlet adjacent the forward end of said bore and a fuel inlet spaced rearwardly from said outlet, said barrel also having in one side thereof a spiral slot extending through the inner and outer surfaces thereof, and a plunger mounted in said bore for reciprocatory movement into and out of the forward end portion of said bore and for movement about a longitudinal axis, said plunger having a passage extending from the forward end thereof rearwardly beyond said slot and also having a port connected with said passage, extending through -the exterior surface of said plunger inthe rear of said slot and arranged to be moved into communication with said slot by the forward movement of said plunger.

5. A fuel injector comprising a cylindrical barrel having an axial bore, a fuel outlet adjacent theforward end of said bore and a fuel inlet spaced rearwardly from said outlet, said barrel `also having in one side thereof a spiral slot extending through the inner and outer surfaces thereof, and a plunger mounted in said bore for reciprocatory movement into and out of the forward end portion of said bore and for movement about a longitudinal axis, said plunger having apassage extending from the forward end thereof rearwardly beyond said slot and also having a port connected with said passage, extending through the exterior surface of said plunger in the rear of said slot an into communication said slot by the forward movement of saidnpunger, said port having a rearward extension to, maintain said communication when said port moves forwardly beyond said'slot.

6. A barrel for a fuel injector comprising a substantially cylindrical structure having a longitudinal bore adapted to receive a plunger, and an inlet spaced rearwardly from the forward end of said bore and communicating with said bore. said structure having in one side thereof a straight line slot oblique to said bore and extending through the inner and outer surfaces of said structure in the rear of said inlet.

'7. A fuel injector comprising a housing hav.- ing adjacent the forward end thereof a fuel delivery conduit, a barrel in said housing having a longitudinal bore, means for connecting said bore with said delivery conduit, said barrel having an inlet spaced rearwardly from Vthe forward end of said bore and communicating with said bore, said housing having a chamber extending about said barrel, communicating with said inlet and having inlet and outlet openings whereby fuel may be circulated through said chamber to supply fuel to said bore and to cool said barrel, a plunger mounted in said bore for movement therein forwardly beyond the inlet to said bore, and means for actuating said plunger.

8. A fuel injector comprising a housing having adjacent one end thereof a fuel delivery conduit and having in the rear of said conduit an inlet chamber, a barrel in said housing having a longitudinal bore connected adjacent the forward end thereof with said delivery conduit, said barrel also having in the rear of said connection an inlet communicating with said inlet chamber and said bore, and having in the rear of said inlet a slot oblique to said bore and communicating with said bore and with said inlet chamber, a plunger mounted in said bore for movement therein forwardly beyond said inlet, said plunger having a passage extending rearwardly from the forward end thereof and a port connected with said passage and arranged to be moved into communication with said slot by the forward movement of said plunger, an outwardly opening check valve between said bore and said delivery conduit, and means for reciprocating said plunger and for moving the same about its longitudinal axis.

9. In a fuel injector a barrel adapted to be removably mounted in a housing and having a longitudinal bore and a fuel inlet spaced rearwardly from the forward end of said bore, the forward end portion of said barrel being of reduced diameter and having an external circumferential recess, a member arranged at the forward end of said barrel and having a diameter approximating the diameter of the reduced end portion of said barrel and having a circumferentialrecess, a disk between said member and said barrel, said disk and said member having alined openings forming an outlet for the bore in said barrel, a check valve supported in said outlet between said member and said disk, and a device extending "about, the adjacent portions of said member and said barrel and into said recesses tov connect said members and said barrel.

10. A fuel injector comprising a housing having adjacent the forward end thereof a fuel delivery conduit and having within the same an annular inlet chamber spaced to the rear of said delivery conduit, a barrel in said housing having a longitudinal bore, an outlet connecting the forward end of Said bore with said delivery conduit and an inlet in the rear of said outlet connecting said bore with said inlet chamber, said barrel also having a slot extending obliquely to said bore and communicating with said bore and said inlet chambsna plunger in said bore having within the same a passage extending from the forward end thereof rearwardly beyond said slot and also having a port connected with the rear portion of said passage and arranged to be moved into communication With said slot by the forward movement of said plunger, a follower in the rear portion of said housing, means for rotatably connecting said plunger with said vfollower for axial movement therewith, means for imparting reciprocatory movement to said follower, a gear mounted on said plunger and held against axial movement therewith, said plunger being connected with said gear for rotation therewith, and means for actuating said gear.

11. A fuel injector comprising a housing having adjacent the forward end thereof a fuel delivery conduit and having within the same an annular inlet chamber spaced to the rear of said delivery conduit, a barrel in said housing having a longitudinal bore, an .outlet connecting the forward end of said bore with said delivery conduit and an inlet in the rear of said outlet connecting said bore with said inlet chamber, said barrel also having a slot extending obliquely to said bore and coin.- municating with said bore land said inlet chamber, a plunger' in said bore having within the same a passage extending from the forward end thereof rearwardly beyond said slot and also having a port connected with the rear portion of said passage and arranged to be moved into communication with said slot by the forward movement of said plunger, a cup shaped follower slidably mounted in the rear portion of said housing, means within said follower for connecting said plunger with .said follower for axial movement therewith and REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,993,759 Stockmeyer Mar. 12, 1935 2,109,785 Starr Mar. l, 1938 2,207,337 Bremser July 9, 1940 2,326,958 Marais Aug. 17, 1943

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