US3255974A

US3255974A - Fuel injection nozzle

Info

Publication number: US3255974A
Application number: US390124A
Authority: US
Inventors: Vernon D Roosa
Original assignee: HARTFORD MACHINE SCREW CO
Current assignee: HARTFORD MACHINE SCREW CO
Priority date: 1964-08-17
Filing date: 1964-08-17
Publication date: 1966-06-14
Anticipated expiration: 1983-06-14

Description

`lune 14, 1966 v. D. RoosA FUEL INJECTION NOZZLE Filed Aug. 17, 1964 INVENTOR. VERNON D. ROOSA BVM?, ATTORNEYS 3,255,974 FUEL INJECTION NOZZLE Vernon D. Roosa, West Hartford, Conn. Hartford Machine Screw Co., P). Box 1440, Hartford 2, Conn.) Filed Aug. 17, 1964, Ser. No. 390,124 5 Claims. (Cl. 239-533) This application is a continuation-in-part of application Serial No. 275,789, filed April 16, 1963, which application is a continuation-in-part of application Serial No. 123,581, filed July 12, 1961 now abandoned.

This invention relates generally to fuel injection nozzles for internal combustion engines and more particularly to an improved nozzle of the type having a plunger valve that is operated by pressurized fuel supplied to the nozzle. My U.S. Patent No. 2,865,675 entitled Fuel Injection Nozzle4 is an example of such a nozzle.

In fuel injection nozzles of the type involved in this invention, it is important that the nozzles discharge a tine atomized spray into the cylinders of the associated engine. To produce such an atomized spray the valve must chatter, or open and close rapidly and frequently, during each injection period. In order to accomplish this, it is essential that the plunger valve be free oating in its guide for free and rapid reciprocation of the plunger in its guide. Accordingly, a primary object of the present invention is to provide an improved nozzle of the plunger valve type capable of precision operation while having greatly reduced susceptability to seizure or binding of the plunger valve and similar nozzle malfunctions.

A further object of this invention is the provision of a precision diesel engine fuel injection nozzle of the reciprocating plunger type which is simplified for economical manufacture and does not require the use of machined forgings or castings.

An additional object of this invention is the provision of a precision fuel injection nozzle of the reciprocating plunger type having a cantilever mounted plunger provided with a portion of reduced lateral stiffness to achieve rapid reciprocation for seating the plunger on the valve seat without seizure or binding of the plunger desipite relative laterial displacement thereof during use.

It is a still further object of this invention to provide an improved precision diesel engine fuel injection nozzle capable of being manufactured with minimum precision machining.

Other objects will be in part obvious and in part pointed out more in detail hereinafter,

The invention accordingly consists in the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereafter set forth and the scope of the application which will be indicated in the appended claims.

In the drawings:

FIG. 1 is a cross-sectional view, partially broken away, of an embodiment of the nozzle of this invention; and

FIG. 2 is a cross-sectional view, partially broken away, of another embodiment of the nozzle of this invention.

Turning now to the drawings in which like numerals refer to like parts, the exemplary nozzle shown in FIG. 1 includes a generally tubular body 10 having a nozzle tip 12 aixed at lone end, and a fuel inlet fitting 16 secured to the body intermediate its ends.

The body member is formed from a length of tubing having a continuous bore 22 extending throughout, which bore is enlarged to provide a front bore portion 23 and a rear bore portion 25. Tip 12 is provided with a parti-spherical end 27 having one or more fuel outlet passages 28 formed therein and with a tubular skirt or i, body member 30 extending therefrom and received in sealing engagement with the side wall of front bore por- United States Patent tion 23. By this construction the tubing used in making the body member 10 may be of a different material than that used for making the tip to minimize material costs and to permit the use of materials having properties specially suited to meet the requirements of the body and the tip respectively.

The nozzle valve of this invention is in the form of an elongated plunger or rod 33 having a generally conical end 34 which coopera-tes with a conical seat 35 adjacent the forward end of tip 12. Plunger 33 is dimensioned to be of smaller diameter than the bore 22 in the nozzle body and thepassageway formed in the skirt 30 of the tip so as to provide a fuel ow passageway. The rear or upper end 36 of the plunger is slidably supported in an upper guide member or collar 38, the plunger portion 36 and the collar 38 preferably having a lap t therebetween to minimize fuel leakage therethrough. Adjacent the upper end .of plunger 33 there is provided a partispherical end portion 40 on which is seated the partispherical recess of spring seat 41 which has a shoulder 42 that receives one end of plunger pressure spring 43. The other end of spring 43 is received by upper spring seat 44 having a parti-spherical recess 45 that rests against ball washer 46 whose position is adjustable along the length of the rear bore portion 25 by internally and externally threaded and longitudinally slotted pressure adjusting screw, or sleeve, 48 threadably received in the upper end of body 10. By the foregoing arrangement of the spring 43,

seats

41 and 40 and adjusting sleeve 48, the plunger 33 is continuously urged toward tip 12 so that tapered portion 34 sealingly engages valve seat 35. The parti-spherical relationship of the spring seats, the ball washer and end portion on the plunger insures that the spring will exert minimum forces laterally of the plunger despite lack of squareness of the ends of spring 43.

In accordance with the operating principles of this type of valve, fuel under pressure will overcome the seating force of the spring 43 to urge the plunger away from the valve seat and the maximum limit of such travel accorded to the plunger is adjustably determined by the lift adjusting screw 50 which is threadably received within a bore of pressure adjusting sleeve 48 and which is provided with an elongated stem 52 disposed concentrically within spring 43, the lower end of which acts as a stop to limit the lift or upward movement of the plunger. The sleeve 48, which is slotted from one end to the other as indicated at 49, and the screw 50, are locked in the desired position by lock nut 51, the tightening of which urges the slotted sleeve 48 -radially inwardly to clamp and lock the screw 50 to set the operating pressure and plunger lift without interfering with the operation of the parti-spherical spring seats for spring 43. The slot 49 also accommodates the discharge of leak-olf fuel which leaks between plunger portion 3 6 and collar 38. l

The fuel inlet fitting 16 generally comprises a connector inlet collar 53 disposed about the nozzle body 10 intermediate its ends and supporting an inlet 5-4 having a central bore that communicates with an aperture 56 formed in the side wall of the nozzle-body between the plunger guide 38 and the tip 12. The other end of the inlet 54 is connected tothe fuel pump. The collar 53 and 'inlet 54 are brazed or otherwise sealed at 58 'to the body 10 to preclude fuel leakage.

Turning now to the details of construction of the guide means for the plunger, it is noted that the bore of tip 12 is provided with a guide portion 60 of a diameter only slightly larger than the major diameter of Athe end portion 62 of plunger 33 so as to provide a sliding fit between the two members thereby to act as a lower guide member for the plunger adjacent the valve seat 35. ln order to permit the passage of fuel through the' lower guide, there is Patented June 14, 1966 i provided, in the embodiment of FIG. 1, `a series of circumferentially spaced flats 65 on portion 62 of plunger 33 which define fuel passageways communicating between ybore portion 22 and the valve seat.

The upper guide member or collar 38 is shown as being provided with external threads which engage mating internal threads provided on the side wall of the bore, which threads are provided with a thread engagement factor of .0080 to .0143 inch clearance on the pitch diameter so that, comparatively speaking, the upper guide member is loosely disposed within the bore. The final positioning of the collar relative to the bore and thus the proper alignment of the plunger relative to the lower guide and valve seat is accomplished through the utilization of a settable material, preferably an epoxy resin, that is disposed in the clearance spaces between the mating threads. The epoxy resin, when cured, sets up into a hard material that rigidly positions the collar relative to the bore of the nozzle body.

In the embodiment of FIG. 1, the lower guide 60 is accurately positioned relative to the valve seat during manufacture of the tip and is, because of the unitary nature of the tip, accurately positioned relative to the valve seat. In view of the very great distance between the lower guide 60 and the upper guide 38 relative to the distance between the lower guide 60 and the valve seat 35, very little movement of the upper guide member is required to permit proper seating of the conical tip 34 in the seat 35 and thus proper alignment of the plunger relative to the nozzle body.

A longitudinal portion 33a of the plunger 33 is necked down as shown in FIG. 1 to reduce the lateral stiffness thereof so that in the event of any misalignment of the guide 38 relative to the valve seat 35 for any cause, the tendency of the plunger to seize or bind within the guide 38 is minimized while retaining the rigidity of the plunger 33 to avoid the curving or whipping of the plunger between guides 38 yand 60.

In the manufacture of the improved nozzle the length of tubing forming the body r is machined from the ends as shown in FIG. 1. The tip 12 is assembled in the bore 23 of the body 10 and sealed thereto'. The inlet 54 and collar 53 are likewise assembled and secured to the body 10 as previously described. The upper guide is then threaded into the nozzle and secured to support the plunger in alignment with the valve seat 35; and the upper valve assembly parts, i.e., the

spring seats

41 and 44, the spring 43 and ball washer 46, the pressure adjusting sleeve 48, the lift adjusting screw 50 and the lock nut 51 are inserted in the body and the nozzle is ready for final adjustment and test.

Referring now to the embodiment of the invention shown in FIG. 2, there is shown another embodiment of this invention in which the plunger 33 is cantilever mounted by guide 38, the lower guide corresponding to the guide 60 of FIG. 1 being eliminated. Also, the spaced ats 65 which are provided on the portions 62 on the plunger 33 of the embodiment of FIG. 1 are eliminated to simplify the nozzle tip design and to cause the fuel to ow to the nozzle discharge openings 28 in an annular column to reduce the possibility of cavitation adjacent the plunger tip 34 and valve seat 35.

It has been found that when the upper guide member 38 is precisely aligned as indicated above in connection with the embodiment of FIG. 1, it provides a cantilever support for the plunger 33 which maintains the conical tip concentrically aligned with the Valve seat 35 without other lateral support or guide means and will function properly to provide an atomized spray discharge from the nozzle despite relative rotation between the plunger and the valve seat.

The elimination of the llower guide is possible since the Valve seat and the plunger may be precisely aligned despite manufacturing variations and tolerances in .the parts of the ftll injection nozzle due to the fact that the upper guide member may be precisely adjusted into alignment with the valve seat. The settable material between the upper guide member 38 and the inner wall of the body member 10 will -accommodate any misalignment or eccentricity in the pitch diameters of the threads on the guide member 38 and the mating threads on the body member 10. Moreover, the provision of a necked down portion of the plunger 33 between the guide 38 and the valve seat 35 will minimize lateral forces on the plunger which tend to cause it to seize in the guide 38. In this connection, the annular column of fuel within the bore 24 between the plunger 33 and the nozzle body 10 will serve to hydraulically damp any lateral movement of the plunger tip due to vibrations encountered in use or otherwise.

In the embodiment of FIG. 2, vthe tip 12 is secured within the front bore portion 23 of the body member 10 with an interference tit. The interference t is accomplished by providing the tip 12 with an outer diameter on the order of .0007 inch larger `than that of the front bore portion 23 of the body 10. The tip may be assembled in `any suitable manner as, for example, by heating the body member 10 to approximately 250 F. t0 expand the bore 23 slightly so that the tip, which is kept at room temperature, may be inserted. Upon the cooling of the body member 10, it will be apparent that the tip 12 is secured to the body member 10 by an interference fit. Such an interference t will provide a high pressure mechanical seal between the tip and the body member 10 to prevent the leakage of fuel therebetween.

After the tip is assembled in the body member 10, the end 23a of the body member 10 is crimped into engagement with the reduced diameter portion 12a of the tip 12 to further mechanically secure the tip to the body member 10.

It is preferred that the upper end of the tip 12 be provided with a groove 12b about the periphery thereof and that the groove be lled with a semi-liquid epoxy resin prior'to assembly of the tip 12 in the body member 10 to provide, after assembly and curing of the resin, `an annular seal ring adhering to the front bore portion 23 and the groove 12b of the tip. It will be noted that the groove is of substantial depth relative to the diameter of the front bore portion 23 so that any differential in the temperatures of the body member 10 and the tip 12 encountered in used as a result of a transient temper-ature gradient thereacross will not cause the epoxy ring 12e to be stressed beyond its elastic limit due to thermal shock as might occur with, say, a thin lm of epoxy between the bore 23 and the tip 12 along the length thereof. The use of this arrangement for securing the tip to the body member 10 is possible despite the manufacturing variations in the concentricity ofthe valve seat 35 and the outer periphery of the tip 12 due to the arrangement heretofore described for precisely aligning and securing the upper guide member 38 concentrically with the valve seat 35.

From the foregoing description of the construction and operation of this improvedfuel injection nozzle, it is noted that there is provided an extremely economical yet precision-operating nozzle of the plunger type. By utilizing a body formed from a length of tubing, the working end of the nozzle (i.e., the portion between the connector inlet collar and the tip) may be economically made sufficiently lon'g to simplify the installation of the nozzle into the engine cylinder head or block and the nozzle cross section diameter or frontal area can be substantially reduced to provide the engine designer with greater latitude in the design of the associated engine and the mounting of other engine accessories and attachments. Additionally, the unique design approach utilized in this invention substantially reduces the manufacturing cost of the nozzle as compared with precision nozzles made from forged and cast parts without sacrifice of quality.

As will be apparent to persons skilled in the art, various modifications and adaptations of the structure above described will become readily apparent without departure from the spirit and scope of the invention,the scope of which is dened in the appended claims.

I claim:

1. A fuel injection nozzle comprising a length of tubing having a valve seat and a discharge orifice at one end and a one-piece plunger mounted within the bore of the tubing in xed alignment with the valve seat for relative reciprocation therewith, a coil spring for biasing said plunger into engagement with the valve seat posi` tioned in the other end of the tubing, an axially adjustable tubular sleeve positioned in the other end of the tubing for adjusting the biasing pressure of the spring, an adjustable -stop disposed within said tubular sleeve and having an extension passing through the coil spring for engaging the end of the plunger to provide a positive stop for limiting the maximum lift of the plunger away from the valve seat, and partispherical seat means at both ends of said spring for eliminating lateral forces on the plunger by the spring in the event of the lack of squareness of the end ofthe spring.

2. A fuel injection nozzle comprising a length of tubing having a valve seat and a discharge orilice at one end and a one-piece plunger mounted Within the bore of the tubing in iixed alignment with the valve seat for relative reciprocation therewith, a coil spring for biasing said plunger into engagement with the valve seat positioned in the other end of the tubing, an internally and externally threaded tubular sleeve positioned in the other end of the tubing for adjusting the biasing pressure of the spring, an adjusting stop threaded Within said tubular sleeve and having an extension projecting through lsaid coil spring for engaging the end of the plunger to pro- 'vide a positive stop for limiting the maximum lift of the plunger away from the valve seat, and partispherical seat means at both ends of said spring for eliminating lateral forces on the plunger by the spring in the event of the lack of squareness of the end of the spring.

3. A fuel injection nozzle as recited in claim 2 wherein the threaded sleeve is longitudinally slotted from one end to the other to provide a leak-olf path for fuel enbustion engines comprising an elongated nozzle body having a bore, a tip providing a valve seat and having a discharge orice on one end of said body, an elongated plunger within the bore having one end cooperating with said valve seat to form a valve, guide means within said bore remote from said tip to mount said plunger for rapid reciprocation toward `and away trom said valve seat, said plunger defining a peripheral clearance with the wall of said bore between said guide means and said valve seat to provide an annular passageway for delivering fuel to said tip, and a fuel inlet aperture through the wall of said nozzle body adjacent said guide means for delivering fuel under pressure -to said annular passageway, said plunger having enlarged end portions and an intermediate necked down portion therebetween to minimize the lateral stiffness of said plunger to compensate for any misalignment in the axes of said guide means and said valve seat, said necked down portion comprising a concavely curvilinear groove around the plunger.

References Cited bythe Examiner UNITED STATES PATENTS 2,391,808 12/1945 Vincent 239-533 2,750,957 6/1956 Tavola 239-533 2,865,675 12/1958 Roosa 239-533 2,959,360 11/1960 Nichols 239-533 2,974,881 3/1961 Garday 239,-'533 3,034,210 5/1962 Le Dong 29-458 3,068,563 12/1962 Reverman 29-458 3,159,350 12/1964 Mangold 239--533 EVERETT W. KIRBY, Primary Examiner.

Claims

1. A FUEL INJECTION NOZZLE COMPRISING A LENGTH OF TUBING HAVING A VALVE SEAT AND A DISCHARGE ORIFICE AT ONE END AND A ONE-PIECE PLUNGER MOUNTED WITHIN THE BORE OF THE TUBING IN FIXED ALIGNMENT WITH THE VALVE SEAT FOR RELATIVE RECIPROCATION THEREWITH, A COIL SPRING FOR BIASING SAID PLUNGER INTO ENGAGEMENT WITH THE VALVE SEAT POSITIONED IN THE OTHER END OF THE TUBING, AN AXIALLY ADJUSTABLE TUBULAR SLEEVE POSITIONED IN THE OTHER END OF THE TUBING FOR ADJUSTING THE BIASING PRESSURE OF THE SPRING, AN ADJUSTABLE STOP DISPOSED WITHIN SAID TUBULAR SLEEVE AND HAVING AN