US3450352A - Fuel injection nozzle and adjustable biasing means therefor - Google Patents

Description

V. D. ROOSA June 17,'1969 FUEL INJECTION NOZZLE AND ADJUSTABLE BIASING MEANS THEREFOR Filed Jan. 13. 1967 United States Patent U.S. Cl. Z39-533 5 'Claims ABSTRACT OF THE DISCLOSURE A precision fuel injection nozzle having a valve lift stop and a biasing spring stop which are independently adjustable and locked, and deep saddles forming spring seats swivelly engaging the valve stern and the biasing spring stop respectively to provide a stable self-aligning spring construction to minimize lateral thrust on the valve.

This invention relates to fuel injection nozzles for internal combustion engines and more specifically to an improvement on the nozzle described in my prior Patent 3,224,684 issued Dec. 21,v 1965 and entitled Fuel Injection Nozzle.

In lthe operation of fuel injection nozzles of the type contemplated by this invention, the plunger or valve is lifted from its seat by the pressure of the fuel delivered to the nozzle from an associated high pressure charge pump to provide timed high pressure charges of fuel to the nozzle. The discharge of fuel from the nozzle is dependent upon the force exerted by a biasing spring which opposed the movement of the valve away from the valve seat as well as the amount of lift or distance the valve is moved from the valve seat under the influence of the fuel pressure. It is therefore important to provide a readily adjustable arrangement for setting the spring force and lift for the nozzle and to maintain the desired settings during long periods of use. It is a primary object of the present invention to provide such an arrangement.

Another object of the present invention is to provide a nozzle having an improved arrangement for independent field adjustment and locking of the spring bias and lift.

Still another object of this invention is to provide an improved nozzle having a hydraulic pressure responsive reciprocating valve wherein the spring seats for the valve are self-aligning to minimize lateral thrust on the valve.

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 is exemplified in the construction hereafter set forth, and the scope of the invention is indicated in the appended claims.

In the drawing:

FIG. 1 is a fragmentary cross-sectional view of a portion of a fuel injection nozzle embodying the present invention; and

FIG. 2 is an enlarged fragmentary cross-sectional view showing exemplary valve lift and spring bias adjusting stops suitable for use in the practice of the present invention.

The exemplary nozzle shown in the drawing and embodying the present invention is generally similar to that illustrated in my aforementioned Patent 3,224,684 and includes an elongated generally tubular body member having a discharge nozzle tip 12 rigidly fixed in one end thereof and a central longitudinal bore 14 extending throughout its length. Located within the central bore 14 is a rod-like plunger stem or valve 16 having a tip 17 LCC which cooperates with a valve seat 18 formed in the nozzle tip 12 to control the discharge of fuel from the nozzle fbody 10. A valve guide 20 tixedly positioned within the lbore 14 of the body 10 at a position remote from the valve seat 18 slidably mounts and precisely aligns the valve 16 to accommodate rapid reciprocal movement of the valve under the influence of the fuel pressure within the bore 14 acting against the bias of spring 22. The nozzle is provided with a fuel inlet 24 communicating with the bore 14 of the nozzle body 10 for the delivery of high pressure fuel to the bore 14 adjacent the guide 20 from an associated charge pump, not shown.

In FIG. 1, the upper end of the valve 16 engages a spring seat 28. The other end of the spring 22 is similarly provided with a spring seat 30 which engages a spring bias adjusting stop 32 with the stop 32 being positioned along the axis of the valve 16 to cause the spring to exert an axial force thereon.

When the nozzle has been assembled and placed in operation, timed charges of fuel under high pressure are introduced through inlet 24 and pass relatively freely along the annular passageway provided between the valve 16 and the bore 14 to the tip 12 of the valve. The high fuel pressure acts on the valve 16 and overcomes the bias of spring 22 t0 move the valve away from the valve seat and the discharge of fuel through the orifices in tip 12 takes place.

When fuel pressure in the nozzle acting against the bias of spring 22 is reduced `by the discharge of the fuel, the spring 22 overcomes the hydraulic pressure acting on the valve 16 and returns it to closed position.

In accordance with one aspect of this invention, novel means are provided for isolating the lift stop 40 from the spring ybiased adjusting stop 32 so that independent adjustments may readily be made. As shown, the lift stop 40 is in the form of an inverted externally threaded cap nut threadably received in the internal mating threads 36 of the tubular body 10. The inwardly turned flange 42 of the lift stop 40` is apertured at `44 to receive the necked down end portion 46 of the valve 16 with the aperture 44 being smaller than the guide portion 47 of the valve so that shoulder 48 of the valve engages the ange 42 to limit the movement of the valve away from the valve seat. A pair of apertures 50 in flange 42 are adapted to receive a Spanner wrench to adjust the lift stop 40. l As described above, the biasing spring 22 exerts an axial force on the end of the valve 16 through spring seat 28 which is bell-shaped to straddle the end 46 of the valve. Spring seat 28 provides a peripheral ange 54 which engages the end of the spring 22.

Engaging the other end of the spring 22 is a second bell-shaped spring seat 30 also providing a peripheral flange 58 which engages the end projection 60- of externally threaded stop 32` The stop 32 is threadably reecived in the internal mating threads 36 of the tubular body 10 and is axially adjustable so as to adjust the biasing force of the spring by means of a screwdriver placed in slot 62.

It will thus be seen that the adjustment of the lift stop 40 and the adjustment of biasing spring 22 by means of stop 32 are independent of each other s0 that, in making a eld adjustment of the spring pressure, a mechanic will not inadvertently change the lift adjustment of the valve.

When the lift stop 40 and the biasing adjustment stop 32 are in the desired adjusted position, they may be locked in place independently of each other in any suitable manner as by an interference fit between the respective threads thereof and the mating threads 36 of the nozzle body 10.

FIG. 2 shows one advantageous arrangement for securing the threads in adjusted position. As shown in FIG. 2, the lift stop 40 is provided with a pair of spaced apart threaded sections 64, 66 which threadably engage the internal threads 36 of the nozzle body 10. Between the spaced apart threaded sections 64, 66 is an intermediate unthreaded portion which is in the form of a plurality of longitudinal struts 68 separated by a plurality of aper tures 70.

A feature of this design is that the helix of the threaded section 64 lags or leads that of threaded section 66 a predetermined amount so that when the threads 66 engage the mating threads 36 of the nozzle body the threads 64 will be slightly offset or out of phase with the threads 36 to place the struts 68 under compression or tension when both the threaded sections 64 and 66 engage the threads 36. This produces a locking action for the lift stop 40 to hold it against movement from its adjusted position without producing destructive shearing forces on the threads and without reducing the wall thickness of the intermediate portion 68 to such an extent that it will not withstand the forces imposed on it in use. Preferably, the struts 68 of lift stop 40 are placed under tension since this will cause the threads 66 to bottom on the mating threads 36 in a direction away from the shoulder 48 to eliminate backlash when the shoulder 48 strikes the ange 42 of the stop.

Mutatis mutandis, the threaded sections 72 and 74, the unthreaded struts 76 and apertures 78 of stop 32 functoin to maintain the stop 32 in adjusted position with the struts 76 preferably under compression to eliminate backlash in the adjustment.

Another feature of the invention is the provision of an arrangement which renders the biasing spring 22 selfaligning and stable despite a lack of squareness of the ends of the spring 22 or the misalignment between the valve 16 and the projection 60 of the adjusting screw 32 due to manufacturing variations. The end 46 of valve 16 swivelly engages spring seat 28, and the projection 60 of stop 32 swivelly engages the spring seat 30 to transmit the biasing force of spring 22 along the line connecting the points of contact of valve end 46 and projection 60.

As shown, the valve end 46 and projection 60 terminate in hemispherical surfaces to provide good bearing surfaces. Likewise, the bell-shaped spring seats 28, 30 provide generally hemispherical mating surfaces which open into diverging conical surfaces for unimpeded swivel action. In addition, the anges 54, 58 or spring seats 28, 30, respectively, engage the ends of the spring at a point below the center of curvature of the engaging portions of the spring seats 28, 30 with the respective projections 46 and 60.

By this construction, any deviation in the squareness of the ends of the spring 22, or axial misalignment of projections 46, 60, will cause the spring seats 28, 30 to tilt to a compensation position nonperpendicular with the axis of the valve and minimize any lateral component of the spring force applied to the valve 16 thereby to minimize any binding between the valve and the valve guide 20. Thus, this arrangement automatically minimizes and compensates for any unbalanced condition of the valve biasing structure.

As will be apparent to persons skilled in the art, various modifications and adaptations of the structure abovedescribed will become readily apparent without departure from the spirit and scope of the invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A fuel injectionnozzle including a nozzle body having a valve chamber, a pressure responsive valve disposed in the chamber, a guide mounting the valve for reciprocable movement in the chamber, a spring biasing the valve toward a valve seat having a discharge orifice and adjusting and locking means for setting the spring biasing force and the lift of the valve from the valve seat, said adjusting and locking means comprises a pair of stops the first of which engages said valve to limit the lift and the second of which engages the spring to set the biasing force thereof, said pair of stops being independent of each other to isolate the adjustment of one from the adjustment of the other, said first stop providing an apertured fiange for receiving the end of the valve and engaging a shoulder on the valve to limit the lift thereof.

2. A fuel injection nozzle including a nozzle body having a valve chamber, a pressure responsive valve disposed in the chamber, a guide mounting the valve for reciprocable movement in the chamber, a spring biasing the valve toward a valve seat having a discharge orifice and adjusting and locking means for setting the spring biasing force and the lift of the valve from the valve seat, said adjusting and locking means comprises a pair of stops the first of which engages said valve to limit the lift and the second of which engages the spring to set the biasing force thereof, said pair of stops being independent of each other to isolate the adjustment of one from the adjustment of the other, wherein at least one of said stops has spaced threaded end sections engageable With mating 'threads of said nozzle body, said threaded end sections being separated by a plurality of struts with the helix of the threads of one section offset from the helix of the threads of the other section.

3. A fuel injection nozzle including a nozzle body having a valve chamber, a pressure responsive valve disposed in the chamber, a guide mounting the valve for reciprocable movement in the chamber, a spring biasing the valve toward a valve seat having a discharge orifice and adjusting and locking means for setting the spring biasing force and the lift of the valve from the valve seat, said adjusting and locking means comprises a pair of stops the first of which limits the lift and the second of which sets the biasing force of the spring, said pair of stops being independent of each other to isolate the adjustment of one from the adjustment of the other, a spring seat swivelly engaging the end of the valve substantially on the axis of reciprocation of the valve, the mating portions of said valve and spring seat being generally hemispherical and engageable for universal tilting.

4. A device as recited in claim 3 wherein the spring seat is bell-shaped and is provided with a ange for engaging the end of the spring at a point below the center of the hemispherical portions thereof,

5. A device as recited in claim 3 wherein the open end of the mating portion of the generally hemispherical spring seat terminates in a diverging conical surface.

References Cited UNITED STATES PATENTS 1,759,367 5/1930 Petersen 239-533 2,002,134 5/1935 Baj 239-533 2,865,675 12/1958 Roosa. 3,224,684 12/ 1965 Roosa 239-533 FOREIGN PATENTS 489,510 6/ 1928 Germany.

M. HENSON WOOD, IR., Primary Examiner.

B. BELKIN, Assistant Examiner.

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