US2075949A

US2075949A - Fuel injection system

Info

Publication number: US2075949A
Application number: US698082A
Authority: US
Inventors: Joseph R Lemon
Original assignee: Excell O Aircraft & Tool Corp
Current assignee: Excell O Aircraft & Tool Corp; Excell-O Aircraft & Tool Corp
Priority date: 1933-11-15
Filing date: 1933-11-15
Publication date: 1937-04-06
Anticipated expiration: 1954-04-06

Description

April 6, 1937. J. R. LEMON 2,075,949

FUEL INJECTION SYSTEM Filed Nov. 15, 1955 a? 13 Pals?! 29 a8 14 a INVENTOR.

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L65./a" FUEL msssulee Jbsg h/ Tc. Lamom Patented Apr. 6, 1937 FUEL INJECTION SYSTEM Joseph R. Lemon, Detroit, Mich assignor to Ex- Cell-O Aircraft & Tool Corporation, Detroit, Mich., a. corporation of Michigan Application November 15, 1933, Serial No. 698,082

11 Claims.

The present invention relates to improvements in fuel injection systems, and has particular reference to a new and improved hydraulically operable injection nozzle.

One of the primary features of the invention resides in the provision of a new and improved nozzle having a valve adapted to be opened and closed by the pressure of the fuel, and in which the fuel for operating the valve is supplied through 10 a single line.

A further object is to provide a nozzle of the foregoing character in which the single line also supplies the fuel for injection.

Further objects and advantages will become apparent as the description proceeds.

In the accompanying drawing, Figure 1 is a fragmentary vertical sectional view through a cyllnder and combustion chamber of an internal combustion engine with a fuel injection nozzle embodying the features of my invention mounted in operative position.

Fig. 2 is a plan view of the nozzle.

Fig. 3 is a longitudinal sectional view of the nozzle taken substantially along line 3-3 of Fig. 4.

Figs. 4 and 5 are transverse sectional views taken respectively along lines 4-4 and 5-5 of Fig. 3; I

Fig. 6 is a diagram illustrating the operation of the nozzle.

30 Fig. 7 is a view similar to Fig. 3 but of a modified form of nozzle.

While the invention is susceptible of various modifications and alternative constructions, I have shown in the drawing and will herein describe in detail the preferred embodiment, but it is to be understood that I do not thereby intend to limit the invention to the specific form disclosed, but intend to cover all modifications and alternative constructions falling within the spirit 4 and scope of the invention as expressed in the appended claims.

Referring more particularly to the drawing,

the fuel injection system may comprise any suitable number of discharge nozzles depending in part on the number of engine cylinders to be 50 stance, a single nozzle 1 is shown mounted to discharge into a combustion chamber 8 in communication with the head end of an engine cylinder 9 in which a piston I0 is reciprocable, and is adapted to be operated periodically in timed rela- 55 tion to the reciprocation of the piston.

The nozzle 1, in its preferred form, has a, sectional body comprising a holder II and a discharge tip I2, which may be provided in any suitable shape, and which in the present instance are generally cylindrical and in endwise engagement. Preferably, the adjacent ends of the holder II and the tip I2 have flat and smoothly lapped contacting faces I3 and I4- affording a pressure tight joint. A flanged nut I5, engaging a peripheral shoulder I6 on the discharge tip I2, is threaded onto the adjacent end of the holder II to secure 10 the parts tightly in assembled relation. The nozzle I is mounted in position, with the discharge tip I2 extending through an opening I! in one wall of the combustion chamber 8, by means of two diametrically opposed lugs I8 on the nut I5 which are rigidly secured to the head of the cylinder 9 by bolts I9.

The discharge tip I2 is formed with a fuel chamber 29, and may be provided with any suit? able number of injection orifices opening to the combustion chamber 8, and adapted to be'connected by fuel pressure operable valves to the fuel chamber. In the present instance, the nozzle I is shown with a single orifice 2| controlled by a valve 22. v

The valve 22, in its preferred form, comprises aconical seat 23 located between the fuel chamber and the orifice 2 I, and a coacting valve member 24 operable by a reciprocable plunger 25. The

plunger 25 is disposed in a bore 26 which opens axially through the discharge tip I2 from the inner face I4 to the fuel chamber 20, and the inner end of which defines a control chamber 21 adapted to contain fuel under pressure. In the operation of the valve 22, the face I3 limits the extent of movement of the plunger 25, and hence determines the degree of valve opening. A dif-' ferent degree of valve opening can be obtained by substituting a plunger 25 of a different length. 40 The inner end of the plunger 25 defines a face or area 28 exposed to the pressure in the chamber 21 and acting in a direction to seat the valve member 24. The other end of the plunger 25 is reduced in size to define an annular face or area 29 exposed to the pressure in the fuel chamber 20 and acting in a direction to lift the valve member 24. When the valve 2I is open, the end face of the valvemember 24 also is exposed to the pressure in the fuel chamber 20, and acts in a direction to hold the valve open. The total effective area of the valve face and the lifting face 29 substantially equals that of the seating face 28. Reciprocation of the plunger 25 is effected by relatively varying the pressures in the chambers 5 20 and 21, i. e., by reversing the pressure differential acting on the faces 28 and 29-24.

One of the important features of the present invention resides in supplying the fuel for both 5

chambers

20 and 21, and for effecting pressure fluctuations therein to operate the valve 22, through the medium of a single fuel supply line 30 connected to the nozzle 1. In the present in-- stance, the fuel supply line 39 is in constant comlO munication with a passage 3| formed in the holder H, and opening to the control chamber 21. Fuel under pressure for injection and to exert a lifting force on the plunger 20 is supplied to the chamber 20 from the chamber 21 through a restricted leakage path of high resistance. This path may be provided in various ways. Thus, the plunger 25 may have a loose fit in the bore25 so that the annular clearance therebetween will define the connecting path, as shown in Fig. '7, wherein this clearance is made to appear on a somewhat larger. scale than other parts of the nozzle so as to facilitate illustration thereof. Preferably, however, the path consists of an axial bore 32 opening from the face |4 into the plunger 25, and communicating at its inner or closed end through a restricted orifice or port 33 with the chamber 20. Where a plurality of nozzles 1, or a plurality of plungers 25 for a series of orifices 2| in a single nozzle, are provided, the leakage paths for the respective plungers may be provided in different ways.

In the operation of the engine, the injection is timed to occur over a predetermined period, variable in duration for example from 0 to of crank shaft rotation. The pressure fluctuations for effecting operation of the nozzle 1 in timed relation to the reciprocation of the piston l0 are illustrated in Fig. 6, wherein fuel pressures in pounds per square inch are plotted along the ordinate and degrees of crank shaft travel are indicated along the abscissa. Between successive periods of injection, the valve 22' is closed, and fuel under a maximum pressure of 5000 pounds per square inch is directed through the line 30 4 and passage 3| to the control chamber 21 as represented by the line AB. Fuel leaking through the bore 32 and the restricted port 33 in Fig. 3 or along the peripheral surface of the plunger 25 in Fig. '1 gradually builds up an equal pressure in the fuel'chamber 20. However, the valve 22 remains closed since the area of the face 29 is less than that of the face 28. The ratio of these areas is such that upon a reduction in the seating pressure acting on the face 28 to below a predetermined point, for example 3,750

pounds per square inch, while substantially maintaining the high pressure in the chamber 29, the valve 22 will open. At the point B, representing approximately top dead center of the piston lo,

a sudden pressure reduction of approximately 40 per cent. along line B.CD to a pressure of 3,000 pounds per square inch is instituted in the chamber 21. The restricted port 33 in Fig. 3 or peripheral clearance between the plunger 25 and the bore 26 in Fig. '1 prevents a corresponding drop in pressure in the chamber 20, and hence the valve member 24 is lifted to start injection at the pointC, representing approximately one and one-half degrees of crank shaft rotation past top dead center. Fuel stored 'in the chamber 20 is thereupon injected through the orifice 2| into the combustion chamber 8. The duration of injection is dependent on the duration of pres- I sure reduction in the chamber 21, and may be varied in accordance with the engine operating requirements. For full load operation, the pressureis maintained at 3,000 pounds per square inch along the line DE, and is then restored suddenly to the initial high pressure along the line E-F. During injection, a slight local pressure drop occurs in the fuel chamber 20 adjacent the lifting areas 29 and 24. @Hence, upon restoration of the seating pressure in the chamber 21, the valve 22 is closed. For small or idling loads,

the seating pressure may be restored immediately along the line DG. Upon closing of the valve 22, the fuel in the chamber 20 is replenished in preparation for the next cycle. 4 I

It will be evident that the pressures 'in the chambers 20 and 21tendslowly. toequalize due to the connecting passage32 33 or the periph-. eral clearance in Flgi'i'Tl However, becausefof the relatively short duration of the m etio'n period, 1 and the restrictedig'character .iof gth'ei iintercommunication between 'the" chambers, gsuch-equalization does notoccurduring'the iniection period, and hence the injection-pressure does'not drop appreciably. On the other hand, the idle period continues during most of the crank shaft travel, and affords adequate time for restoration of the fuel supply in the fuel chamber 20 for the next injection.

The fuel chamber 20 preferably has a relatively large pressure storage capacity so that the injection pressure will remain practically constant.

This pressure storage capacity may be obtained in various ways, for example by providing a large confined space,'defined by the chamber 25 alone or with a supplemental space open thereto, and/or by providing a confined space with resilient walls, adapted for direct communicationthrough the valve 22 with the orifice 2|. Where a plurality of nozzles 1 are employed, the desiredpressure storage capacity may beobtained by interconnecting the various fuel chambers. In the present instance, the desired pressure storage capacity is obtained by means of a reservoir or accumulator chamber 34 in direct and unrestricted communication with the chamber 29, and in effect forming a part thereof. The chamber 34 is defined by a cylindrical shell 35 of slightly resilient material, suchas seamless steel tubing, closed at one end by the holder H, and at the other end by a head or closure member 35. A central tube 31 extends axially through the chamber 34, and at one endis seated in a recess 33 in the holder II in direct communication with the passage 3|, and atthe other end extends outwardly through an axial sleeve 39 integral with the member 35. The discharge end of the supply line 30 is removably secured, as by a nut 49, to the outer end of the sleeve 39 in direct communication with the outer end of the tube 31. Preferably, the holder theshell 35, the closure vmember 35 and the tube 31 are tightly and perbility of the fuel, a 'large pressure storage capacity is obtained which serves to maintain the in timed sequence.

65 valve member movable with 5 1 is effected solely by pressure fluctuation in the single control and fuel supply line 30. When a plurality of nozzles l are provided for the cylinders of a multi-cylinder engine, the pressure fluctuations in the respective lines are effected Any suitable means (not shown), such for example as an adaptation of the fuel distributor disclosed in said copending application, may be provided to supply the fuel under pressure and to effect the desired pressure 15 control.

I claim as my invention:

1. A unitary fuel injection nozzle comprising, in combination, a body having a valve chamber with an outlet opening from said seat, a pressure storage space within said body and having a resilient wall and being in open communication with" said valve chamber, a control chamber, and a bore connecting said chambers, a plunger reciprocable in said bore and having oppositely acting pressure faces exposed respectively in said chambers, one of said faces being formed with a valve member adapted to coact with said seat, means for supplying fuel under pressure to said control chamber, and a restricted leakage path located within the confines of said bore longitudinally of said plunger and independent of said space and establishing a direct constant intercommunication between said valve chamber and said means for permitting a gradual flow of fuel on occasion to said valve chamber.

2. A fuel injection nozzle comprising, in combination, a body having a valve chamber with an outlet valve seat, a discharge passage opening 40 from said seat, a control chamber, and a bore connecting said chambers, a plunger reciprocablc in said bore and having oppositely acting pressure faces exposed respectively in said chambers, one of said faces being formed with a valve member adapted to coact with said seat, said plunger being substantially smaller in diameter than said bore to define a restricted leakage path between said chambers adapted to permit a gradual equalization of the pressures therein, and means for supplying fuel under pressure to said control chamber, whereby predetermined pressure fiuctuations in opposite directions in said means will cause said valve member. to move respectively into and out of engagement with said seat.

3. A fuel injection nozzle comprising, in combination, a body having a valve chamber with an outlet valve seat, a discharge passage opening from said seat, a control chamber, and a bore connecting said chambers, a plunger reciprocable in said bore and having oppositely acting pressure faces exposed respectively in said chambers, the area of the pressure face exposed in said control chamber being as large as that of the pressure face exposed in said valve chamber, a said plunger and adapted to coact with said seat, said plunger being formed with a passage open at one end to said control chamber and with a restricted leakage orifice connecting the other end of said passage to said valve chamber, and passage means for supplying fuel under pressure to said control chamber, whereby predetermined pressure fluctuations in opposite directions in said means will cause said valve member to move respectively into and out of engagement with said seat.

stricted passage open at one valve seat, a discharge passage 4. A fuel injection nozzle comprising, in combination, a body having a valve chamber of relatively large storage capacity with an outlet valve seat, a discharge passage opening from said'seat, a control chamber of relatively small capacity, and a bore connecting said chambers, a plunger reciprocable in said bore and having oppositely acting pressure faces exposed respectively in. said chambers, one of said faces being formed with a valve member adapted to coact with said seat and v being equal in effective area tothe other of said faces when said member is lifted and less in effective area than said other face when saidmemb'er is seated, said plunger being formed with a reend to said control chamber and at the otherend'to said valve cham-' ber, and means for supplying fuel under pressure to said pressure chamber, whereby equal-pressures in said chambers will cause said valve member tov be seated and a sudden pressure drop in said control chamber will effect member.

5. A fuel injectionnozzle comprisingfln combination, a body having a confined chamber and a control chamber, a reversibly movable pressure responsive element interposedbetween and having pressure faces at opposite sides exposed respectively to said chambers, the area of the pressure face exposed in said control chamber being as large as that of the pressure face'expos'ed in said confined chamber, an injection valve operable by said element, a restricted leakage passage formed in said element and establishing intercommunication between said chambers, and means for supplying fuel under pressure to said lifting of said valve control chamber, said confined chamber being adapted to receive fuel from said control chamber only through said restricted passage.

6. A fuel injection nozzle comprising, in combination, a body section, a cylindrical shell mounted on one end of said section and defining a confined reservoir chamber, a discharge tip mounted on the other end of said'section and formed with a valve chamber and a control chamber and with a discharge passage opening from said valve chamber, a valve for controlling said passage, means connecting said reservoir chamber and said valve chamber, a pressure responsive member exposed at opposite sides to said valve and control chambers, a restrictedleakage path" connecting said valve and control chambers, a tube extending through said reservoir chamber and opening to said control chamber, and a fuel supply conduit connected to said tube.

7. A fuel injection nozzle comprising, in combination, a body having a valve chamber and'a control chamber, an element reciprocable in said body and having oppositely acting pressureiiaces exposed respectively in said chambers, means for directing fuel under pressure to said control chamber, a restrictedfiow passage located en.-. tirely within saidbody and independent of said last mentioned means and extending from said, control chamber to said valve chamber along said element to establish a direct constantly open in-- tercommunication between said chambers for permitting a gradual equalization of the pressures therein, said valve chamber beingadapted to receive fuel under pressure from'said control chamber only through said restricted passage, said element being hydraulically operable solely in response to the varying differential determined by the fuel pressures acting on said'faces, and injection valve means operable by said element.

8. A fuel injection nozzle comprising, in combination, a body section, a cylindrical shell secured to one end of said section and defining a confined reservoir chamber, a discharge nozzle 5 removably secured to the other end of said section and formed with a valve chamber and a control chamber and with a discharge passage opening from said valve chamber, the face of said discharge tip adjacent said body section being formed with an annular groove, passages formed in said body section and establishing communication betweenvsaid reservoir and said groove, passages in said discharge nozzle and establishing communication between said valve chamber and said groove, a pressure responsive member reciprocable in said discharge nozzle and having oppositely acting faces exposed respectively in said chambers, the area of the face exposed in said control chamber being at least as great as the area of the face exposed in said valve chamber, a restricted bore extending longitudinally in said member and opening at opposite ends respectively to said valve and control chambers, and means for supplying fuel under varying pressure to said control chamber.

9. A unitary fuel injection nozzle comprising, in combination, a body having an enlarged valve chamber, a discharge orifice opening from said chamber, a valve seat at the inlet of said orifice, a control chamber and a bore connecting said chambers, an element reversibly slidable in said bore solely by hydraulic pressure and having a valve member on one end adapted to engage said valve seat and having a lifting pressure face about said valve member constantly and freely' exposed in said valve chamber and a seatingpressure face on the other end exposed in said control chamber and at least equal in eifective transverse area to the aggregate area of said valve member 40 and said lifting face, means for supplying fuel under pressure to said control chamber, and means defining a restricted constantly open leakage passage in said body eflecting adirect uninterrupted intercommunication along said ele- 4 ment betweensaid chambers, and affording means for the supply of fuel solely from said control chamber directly to said valve chamber.

10. A fuel injection nozzle comprising, in combination, a body having an enlarged valve chamber, a discharge orifice opening from said chamber, a valve seat at the inlet of said orifice, a control chamber and a bore connecting said chambers, an element reversibly slidable in said bore solely by hydraulic pressure and having a valve member on one end adapted to engage said valve seat and having a lifting pressure face about said valve member constantly and freely exposed in said valve chamber and a seating pressure face on the other end exposed in said control chamber and at least equal in effective transverse area to the aggregate area of said valve member and said lifting face, means for supplying fuel under pressure to said control chamber, means defining a restricted constantly open leakage passage in said body effecting a direct uninterrupted in- .tercommunication along said element between said chambers, and an enlarged storage reservoir out of direct communication with said control chamber and in open intercommunication with said valve chamber independently of said leakage passage.

11. A fuel injection nozzle comprising, in combination, a body having a valve chamber with an outlet valve seat, a discharge passage opening from said seat, a control chamber, and a bore connecting said chambers, a plunger reciprocable in said bore and having oppositely acting pressure faces exposed respectively in said chambers, the area of the pressure face exposed in said control chamber being as large as that of the pressure face exposed in said valve chamber, a valve member movable with said plunger and adapted to coact with said seat, said to define a restricted passageopening from said control chamber through said bore to said valve chamber, and passage means for supplying fuel under pressure to said control chamber, whereby predetermined pressure fluctuations in opposite directions in said means will cause said valve member to move respectively into and out of engagement with said seat.

JOSEPH R. LEMON.

plunger being formed