US3055593A - Fuel injection nozzle - Google Patents

Description

SePt- 25, 1952 c. H. MAY ETAL 3,055,593

FUEL INJECTION NOZZLE Filed May 2, 1960 2 Sheets-Sheet 2 lfd ,.522 INVENTORS.

United States Patent O 3,055,593 FUEL INJECTION NOZZLE Claude H. May and Keith H. Rhodes, Racine, Wis., as-

`signors to Walker Manufacturing Company, Racine, Wis., a corporation of Delaware Filed May 2, 1960, Ser. No. 26,125 4 Claims. (Cl. 239-87) This invention relates generally to fuel supply systems for internal combustion engines and more particularly to a fuel injector for such an engine. j

One problem characteristically associated with the injection of fuel directly into the working cylinder of an internal combustion engine is the difliculty in positively metering the quantity of fuel injected during each cycle of the engine without resorting to relatively complex operating and control mechanisms both internally and externally of the injector.

A fuel injector in accordance with the present invention presents a novel solution to this problem by metering -the amountof fuel injected during each working cycle in `response to Ithe delivery pressureof the fuel, variations in delivery fuel pressure effecting a corresponding variation in the displacement ofthe fuel injector.

. Accordingly, one object of the present invention is an n improved fuel injector. y

Another object is a fuel injector that is relatively small in size. e VAnother object is a fuel injector having a minimum of critical tolerances and therefore relatively inexpensive to build.

Another object is a -fuel injector having a constant stroke and variable displacement.

Another object is a fuel injector wherein the quantity of fuel delivered to the combustion chamber is controlled by the delivery pressure of the fuel from a separate fuel supply transfer pump. n

Other objects andv advantages of the present invention Awill become apparent from the following description wherein reference is made to the'drawings, in which:

FIGURE 1 is a sectional side elevation of a fuel injector iin accordance with one embodiment of the present invention; n l

FIG. 2 is a cross-sectional view taken substantially along the line 2 2 of FIG. 1;

f' FIG. 3 i-s a sectional side elevation of another embodiment of the present invention; and Y FIG. 4 is a Isectional viewtaken substantially along the line 4 '4 of FIG. 3. j l e n A fuel injector 10, in accordance with one embodiment of the present invention, comprises a' gerierallylcylindrical housing 12 having a threaded lower end portion 14 for acceptance within, for example, a suitable aperture in `the cylinder head of a conventional internal combustion engine (not shown).

An upper end portion 16 of the housing 12 `hasan in- 'i terhally threaded portion '17e therein for the acceptance of la suitably threaded lower end portion 18 `of a valve housing 19. The'valv'e housing19 extends upwardly `from the housing y12and has a threaded bo1e720 in-an upper end portion 21 for the acceptance of a conven` `tional conduit rlocking screw 22. The screw'22 has a central lbore 23 therein for the acceptance of a fuel supply tube 24j that runs from a fuelrtransfer pump`(not shown). Fuel is conducted to the injector 10 through the conduit 24 under a predetermined pressure, variations of which effect control of the quantity of fuel injected on eachY stroke of the injector 10, in a manner to be described. i j The valve housing e with the bore 20 therein for the passage of fuel down- 19 `has a bore30 communicating n 3,055,593 Patented Sept. 25, 1962 ICC wardly into a check valve chamber 32. The bo-re`30 is normally closed by a cheek valve 34 that is biased against an annular frusto-co-nical valve seat 36 by a helical compression spring 38. The compression spring 38 is seated in a counterbore 40 in a downwardly extending shaft 42.

lThe shaft 42 has a threaded upper end portion 44 that is accepted in a suitably -threaded bore 46 in the lower end portion 18 of the valve housing 19. A suitable sealing washer 50 is interposed between -an upper end face 52 on the shaft 42 and an end face 54 of the bore 46 to effect la fluid seal therebetween. An `axial bore 56 in the shaft 42 provides for the conduction of fuel down wardly from the valve chamber 32 and the counterbore 40 therein int-o a metering chamber 60.

The housing 12 has a plurality of transverse apertures 70 therein that communicate with a peripheral chamber 72 defined by an annular resilient boot 74. The boot 74 has a pair of beads 76 and 78 thereon that are seal-ably engaged in complementary annular recesses 80 and 82 in the valve housing 19 and housing 12, respectively, and

an aperture 84 therein that communicates with a nipple 86 for the conduction of leakage fuel to a fuel reservoir (not shown). Y

The housing 12 has a central bore 90 at the lower end 14 thereof that communicates with a bore 92 of relatively largerinternal diameter. The junction of the bores 90 `and 92 denes an annular transverse shoulder 94, that `functions in a manner to be described. A reciprocable cylinder is slidably disposed within the bores 90 and 92 of 'the housing 12 for movement longitudinally thereof. The cylinder 100 has a plurality of annular peripheral flanges 102, 104, and 106 that slidably engage the wall 92 of the housing 12. A suitable sealing washer 105, for example an O-ring, is disposed between the flanges 104 and 106 to effect a fluid seal between the cylinder `100 and the housing 12.

A helical compression spring 110 extends between a lower end face 112 on the valve housing 19 and an upper face 114 on the flange 102. The spring 110 normally `biases the cylinder downwardly with respect to the housing 12, a lower end face 116 on the flange 106 engaging the shoulder 94 -to define a lowermost position for the Vcylinder 100 with respect to the housing 12.

A tubular sleeve 120 is disposed about the shaft 42 for slidable telescoping movement longitudinally thereof within the cylinder 100. The sleeve sealably engages an inner surface 122 of the cylinder 100. The sleeve 120 has an upperpend portion 124 of reduced diameter, to delinea Vtransverse 'annular shoulder 126 for the seating of -a helical compression spring 128. The compression spring 128 extends between the shoulder 126 and a radially inwardly extending end flange 130 on the cylinder 100 to normally bias the sleeve 120 downwardly, as seen in the drawings, with respect to the cylinder 100 and shaft 42. The sleeve 120 has a counterbore 140 at a lower end 141 thereof, Ithe upper end face 142 of which denes an annular transverse surface for a reason to be discussed. The lowermost position of the sleeve 120 with respect to the cylinder 100 is defined by engagement of an `end face 143 on the sleeve 120 with a seating ,Washer v150. The sea-ting washer is biased against dene the axial relationship therebetween.

The nozzle 160 has a threaded central bore `180 for the acceptance of a suitably threaded lower end portion 182 of a nozzle spring retainer 184. The nozzle spring retainer `184 has a radial ange 186 with a counterbore 188 therein for the acceptance of a pair of nozzle springs 190 and 192. The nozzle springs 190 and 192 comprise a pair of Belleville washers stacked with the dished portions thereof in opposed relation. The upper washer 192 is engageable with a conventional retainer ring 194, having a plurality of apertures 195 therein for the passage of fuel downwardly through the nozzle 160, that is seated in an annular recess 196 in a valve 200.

The valve 200 has a truncated conical valve face 202 that is seated in sealing relationship against a complementary conical valve seat 204 in the nozzle 160.

Upon the occurrence of lsuitable conditions, to be described, during each cycle of the internal combustion engine (not shown) fuel pressure within the conduit 24 dislodges the inlet check valve 34 from its seat 36, thereby passing fuel into the check valve chamber 32 and metering chamber 60. The fuel exerts a pressure against the transverse annular shoulder 142 on the sleeve 120, thereby biasing the sleeve 120 upwardly with respect to the cylinder 100 against the downward bias of the helical compression spring 128. When the upward bias of the fuel on the shoulder 142 is sufficient to balance the downward bias of the spring 128, the sleeve l120 is stabilized in a metering position. Obviously, higher fuel pressures bias the sleeve 120 upwardly to relatively higher positions within the cylinder 100, thereby to enlarge the metering chamber 60.

As the piston of the engine (not shown) progresses on a compression stroke, compression pressure within the working cylinder (not shown) is exerted on the lower end face 161 of the nozzle `1.60 tending to drive the nozzle 160 and cylinder 100 upwardly with respect to the housing 12 against the downward bias of the spring 110. This upward movement of the nozzle 160 and cylinder 100 tends to increase the pressure within the metering chamber 60, the increased pressure on the transverse shoulder 142 of the sleeve 120 pushing the sleeve 120 to its uppermost position with respect to the cylinder 100 against the end wall 130 of the cylinder 100 and closing the inlet valve 34. Because the fuel within the metering chamber 60 is relatively incompressible, the volume of the metering chamber -60 remains relatively constant from the time that the inlet valve 34 closes until the sleeve 120 reaches its uppermost position against the end wall 130.

As engine compression pressure continues to rise in the working cylinder (not shown) the fuel pressure in the metering chamber 60 continues to rise until it is suicient to bias the valve 200 downwardly with respect to its seat 204 in the nozzle 160. Upon the occurrence of relative movement between the valve 200 and nozzle 160 fuel is forced past the conical portion 202 of the valve 200 into the working cylinder of the engine (not shown). By the principle of the differential areas the pressure in the metering chamber 60 is relatively much higher than the pressure in the engine combustion chamber (not shown). When the valve 200 opens, the nozzle 160 and cylinder 100 move upwardly with respect to the shaft 42 until the cylinder 100 strikes its datum point against the upper end 44 of the shaft 42. When this condition obtains, the volume of the metering chamber 60 is minimized, and the injection of fuel is terminated.

It will be noted that the commencement of injection is controlled by the preloading of the nozzle springs 190 and 192. This spring force and the combustion chamber pressure acting on the valve 160 oppose the bias of the fuel in the metering chamber 60 acting on the upper end 201 of the valve 200. As the pressure rises in the metering chamber 60 by the principle of diiferential areas, a fuel pressure is achieved in the metering chamber 60 sufcient to bias the valve 200 downwardly With respect to the nozzle 160 and initiate the injection of fuel into the combustion chamber (not shown).

As pressure in the working cylinder (not shown) decreases, due to retraction of the piston on the power stroke, lthe cylinder is biased downwardly by the spring 110. When the pressure of the fuel remaining in the metering chamber 60 is lowered sufficiently to create a pressure differential on opposite sides of the valve 34, fuel flows past the valve 134 into the metering chamber and biases the sleeve upwardly until a pressure balance occurs between the downward bias of the spring 128 and Vthe upward bias of the fuel on the surface 142. The position of the sleeve 120 with respect to the shaft 42 and cylinder l100, at which the balance -condition occurs is therefore determined by the pressure of the fuel in the conduit 24. ln this manner the quantity of fuel injected by the injector 10 on each stroke thereof is relatively easily regulated by controlling the upstream pressure of the fuel as by conventional means (not shown).

Referring to FIGS. 3 and 4, a fuel injector 300, adapted to be mechanically actuated as by a cam 301, comprises a pump cylinder 302 having a threaded lower end portion 306 for acceptance in, for example, a suitable aperture in the cylinder head of a conventional internal combustion engine (not shown). An upper end portion 308 of the cylinder 302 extends into a cylindrical housing 310, as will be described.

The cylinder 302 has a threaded portion 320 intermediate the end portions 306 andl308, that is engageable in a suitably threaded bore 322 in a lower end portion 324 of the housing 310. The housing 310 is located axially with respect to the cylinder 302 by a lower end face 326 thereon that is biased towards a transverse shoulder 328 on the housing 302, upon relative rotation between the cylinder 302 and housing 310. A suitable sealing washer 330 is interposed between the end face 326 and shoulder 328 to effect a fluid seal therebetween.

The upper end portion 308 of the cylinder 302 is of relatively smaller diameter than the threaded portion 320 thereof to provide an `annular space between the end portion 308 and the housing 310 for the acceptance of an operating spring 334. The operating spring 334 has an upper end portion 336 that is engageable with a lower end face 338 on a valve housing 340 and a lower end portion `341 that is seated on a transverse shoulder 342 on the cylinder 302. The operating spring 334 normally biases the valve housing 340 upwardly with respect to the cylinder 302 and injector housing 310.

A cam block 350 having a cam surface 352 on the upper end face thereof for engagement with the cam 301, is secured to the valve housing 340 for movement therewith. The cam block 350 has a threaded transverse bore 360 therein for the acceptance of a conventional conduit locking screw 362. The screw 362 has a central bore 364 for the acceptance of an end portion 366 of a flexible fuel supply conduit 368. The cam block 350 has a vertical bore 370 therein that communicates with the transverse bore 360 for the passage of fuel outwardly of the cam block 350.

A threaded upper end portion 372 of the valve housing 340 is threadably engaged in a complementary threaded bore 374 in a lower end portion 376 of the cam block 350. A suitable sealing washer 378 is interposed between a lower end face 380 on the cam block 350 and a transverse shoulder 382 on the valve housing 340 to eiect a fluid seal therebetween.

The valve housing 340 has a vertical bore 390 and a chamfered counterbore 392 therein in fluid communicating relationship with the bore 370 in the cam block 350. A truncated conical valve seat 393 extends between the bore 390 and a bore 394 to provide a seat for a spherical ball check valve 400. The valve 400 is movable longitudinally of the injector 300 in a chamber 395 delined by the bore 394. The valve 400 is normally biased against-the seat 393 by a helical compression spring 402 that extends between a transverse 'end' face'404 of a counterbore 406 iur-a flanged upper end portion 408 of v a shaft 410, and the ball 400. i

The flange 408 of the shaft 41.0 is engageable in a complementary threaded bore 412 inthe valve housing 340. A suitable washer 413'isfinterposed between an end face 41-4 ofthe bore 412 and an upper end face 415 on the shaft 410 to eifect a iluid seal therebetween. The shaft 410 has a downwardly extending end portion 416 with a central passage 417 therein for the passage of fuel downwardly from the Valve chamber V395 into a fuel metering chamber 41-8. The shaft extension 416 `extends through an aperture 419 in the upper end 308 of the cylinder 302.

A fuel metering sleeve 450 is coaxially disposed, in telescoping relationship with respect to the lower end portion -416 of the shaft 410, in a central bore 452 in the cylinder 302. The sleeve 450 is normally biased downwardly with respect to the cylinder 302 by a helical compression spring 456 that extends between an annular shoulder 458 on the sleeve 450 and a transverse spring seat 460 on the upper end 308 of the cylinder 302. An upper end portion 462 of the sleeve 450 is of reduced diameter for the accommodation of the spring 456 between the inner wall 452 of the housing 302 and the sleeve 450. The sleeve 450 has a counterbore 464 in the lower end thereof having a transverse end face 466 of a predetermined area for a reason to be discussed.

The injector housing 310 has a pair of annular peripheral grooves 470 and 47-2 thereon for the acceptance of a pair of complementary ribs 474 and 476 of a drain ring 480 in fluid sealing engagement. The drain ring 480 has an aperture 481 in uid communicating relationship with a tubular extension 482 and with an aperture 486 in the housing 310 for the passage of leakage fuel back to a fuel reservoir (not shown).

A nozzle 500 is secured to the lower end 306 of the cylinder 302 for the injection of fuel into a working cylinder (not shown). The nozzle 500 has a threaded upper end portion 502 that is threadably engaged in a suitably threaded bore 504 in the lower end 306 of the cylinder 302. A suitable sealing washer 506 is interposed between an end face 508 of a counterbore 510 in the cylinder 302 and a radial shoulder 512 on the nozzle 500 to effect a fluid seal between the housing cylinder and the nozzle `500.

The nozzle 500 has a `bore 520 and threaded counterbore 522 therein for the acceptance of a suitably threaded lower end portion 524 of a spring retainer 530. The spring retainer 530 has a radial flange 532, a bore 533 and counterbore 534, an end face 535 of which defines a seat for a pair of oppositely dished, stacked Belleville washers 540 and 542. The washer 542 engages the end face 535 of the spring retainer 530 and the washer 540 engages a retainer ring 544 that is engaged in a suitable annular groove 546 in a valve 550.

The pintle valve 550 extends axially through the bore 533 in the spring retainer 530 and has an upwardly convergent truncated conical lower end portion 552 adapted to be seated in a complementary upwardly convergent conical Valve seat 554 in the nozzle 500. The Valve 550 is normally biased upwardly against its valve seat 554 by the Belleville washers 540 and 542.

At an appropriate time, at or about the completion of the compression stroke of a piston within a working cylinder (not shown), the injector 300 is actuated, as by the cam 301, Ito inject a metered quantity of fuel into the combustion chamber. Movement of the cam 301 downwardly effects a similar movement of the cam block 350, metering valve housing 340 and shaft 410. The aforementioned assembly is biased downwardly, with respect to the housing 310 and cylinder 302 against the bias of the spring 334. This downward movement of the plunger 410 tends to raise the pressure of fuel within the metering chamber 418. As fuel pressure in the pump chamber 418 rises, the increased pressure effective on the transverse shoulder 466 of the sleeve 450tends to bias the sleeve 450 upwardly to an uppermost position with respect to the cylinder 302 and plunger 410 against the end wall 308 of the cylinder 302. Because the fuel within the pump chamber 418 is relatively incompressible, the volume of the pump chamber remains relatively constant from the time that the inlet valve 400 closes until the lsleeve 450 reaches its uppermost position against the end wall 308. As fuel pressure in the pump chamber 418 continues to rise due to downward movement of the shaft v410, the valve 550 is biased downwardly against the bias of the springe 540 and 542 thereby unseating'the valve 550 from i-ts seat 554 and injecting fuel under pressure into the working cylinder. Upon the occurrence of the aforementioned pressure condition in the pump chamber 418, fuel is forced past the conical portion 552 of the valve 550 under relatively higher pressure than the iiuid pressure in the working cylinder. Continued movement of the shaft 410 downwardly under the bias of the cam 301 reduces the volume of the pump chamber 418 to a minimum thereby completing the injection stroke.

As the shaft 410 moves upwardly with respect to the cylinder 302, under -the bias of the operating spring 334, lthe relatively lowered fuel pressure within the pump chamber 418 creates a pressure differential on opposite sides of the ball check valve 400 which thereupon moves downwardly from the seat 393 under the bias of fuel pressure in the conduit '368 thereby to ll the metering l chamber 418 with fuel. The fuel, under a pressure determined by a suitable valve (not shown), exerts an upward bias against `the transverse annular shoulder 466 on the sleeve 450 thereby to bias the sleeve 450 upwardly with respect to the cylinder 302 and plunger 410 against the normal downward bias of the spring 456. When the downward bias of the spring 456 is balanced by the upward bias of the fuel on the shoulder 466, the sleeve 450 stabilizes at an intermediate or metering position. Relatively higher fuel pressures bias the sleeve 450 upwardly with respect to the cylinder 30-2 to a greater degree, thereby enlarging the chamber 418 and, upon the injection stroke discussed hereinbefore, conditioning the injector for the injection of a greater volume of fuel into the working cylinder.

It will be noted that the commencement of injection of fuel from the metering chamber 418 into the working cylinder of the engine (not shown) is controlled by the pre-loading of .the nozzle springs 540 and 542. Upon the occurrence of a suflicient fuel pressure within the metering chamber 418, effective on the pintle valve 550, the valve 550 is biased to the open position. Also, the mechanically actuated fuel injector 300 features automatic advance of the injection timing in that, as the quantity of fuel injected increases, the start of injection occurs earlier in the power cycle.

One of the principles employed in the development of the aforementioned fuel injector is the utilization of long leak path sealing which permits relatively large tolerances between the relatively moving parts, thereby materially reducing the t versus fuel and pressure leakage problem heretofore inherent in known fuel injectors. The novel orientation and function of the structural elements that implement this principle, in combination with the provision for fuel pressure controlled metering and the structures that render itp-racticable, result in a fuel injector that presents a major step forward inthe fuel injector art.

While it will be apparent that the embodiments of the invention herein disclosed are well calculated to fulfill the objects of the invention, it will be appreciated that the invention is susceptible to modication, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

What is claimed is:

1. A fuel injector for an engine comprising a tubular housing, means supported by said housing having a fuel inlet aperture for fuel under pressure, a member reciprocable Within said housing in timed relationship relative to an engine cycle defining a portion of a fuel metering chamber, said fuel metering chamber being in iiuid communicating relationship with said fuel inlet, an inlet valve for closing said fuel metering chamber with respect to said fuel inlet, means fixedly supported by said housing defining a second portion of said metering chamber for varying the pressure of fuel in said metering chamber upon relative movement between said member and said housing, means defining a third portion of said metering chamber movable with respect to said member and said housing for varying the volume of said metering chamber in response to variation in fuel pressure in said fuel inlet, and a discharge valve communicating with said metering chamber and openable upon the occurrence of a predetermined fuel pressure therein.

2. A fuel injector in accordance with claim 1 wherein said fixedly supported means comprises a cylindrical member having a central passage for the conduction of fuel into said metering chamber.

3. A fuel injector in accordance with claim 2 wherein said means defining a third portion of said metering chamber is disposed in concentric slidable relationship about said fixedly supported means.

4. A fuel injector in accordance with claim l wherein said housing, said reciprocable member, said fixedly supported means, and said means defining a third portion of said metering chamber are mounted in coaxial relationship.

Tabb et al. Nov. 18, 1941 Dickson Aug. 21, 1956

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