US3704694A

US3704694A - Internal combustion engine with an air inlet valve and a fuel injection valve

Info

Publication number: US3704694A
Application number: US104319A
Authority: US
Inventors: Heinz Gilewski; Jurgen Wolf
Original assignee: Volkswagen AG
Current assignee: Volkswagen AG
Priority date: 1970-01-15
Filing date: 1971-01-06
Publication date: 1972-12-05
Anticipated expiration: 1989-12-05
Also published as: DE2001626A1; JPS4936453B1

Abstract

An air inlet valve and a fuel injection valve cooperate with a common combustion chamber of an internal combustion engine cylinder to supply a mixture of air and fuel thereinto in properly timed relation. The air inlet valve comprises a valve body covering with a valve seat for controlling inlet of air into the combustion chamber and having a hollow valve stem, the fuel injection valve being disposed for operative movement in said stem to inject fuel into the combustion chamber when the inlet valve is opened.

Description

O Unlted States Patent 1151 3,704,694

Gilewski et a1. [45 D 5, 1972 541 INTERNAL COMBUSTION ENGINE 2,072,437 2/1937 Wurtele ..123/9o.12 WITH AN AIR INLET VALVE AND A 2,179,278 11/1939 Wurte1e.... ..123/32 FUEL INJECTION VALVE 2,280,386 4/1942 Dickson ..123/139 [72] Inventors: Heinz Gilewski; Jurgen Wolf, both FOREIGN PATENTS OR APPLICATIONS of Wolfsburg, Germany 951,603 10/1956 Germany ..123/32 [73] Assignee: Volkswagenwerk Aktiengesellschaft,

wolfsburg' Germany Primary Examiner-Laurence M. Goodridge [22] Filed: Jan. 6, 1971 Assistant Examiner-Ronald B. Cox

Attorney-Watson, Cole, Grindle & Watson [21] Appl. No.: 104,319

[57] ABSTRACT [30] Foreign Applicatim Priority Data An air inlet valve and a fuel injection valve cooperate with a common combustion chamber of an internal 1970 Germany P Q1 @1616 combustion engine cylinder to supply a mixture of air [52] U.S. C1. ..123/32 VN, 123/32 R and fuel thereinto in P p y timed relation The air [51] 1nt.Cl ..F02b 3/00 inlet Valve Comprises a Valve y covering with a [58] Field of Search ..123/32 VN v lv seat for controlling inlet of air into the bustion chamber and having a hollow valve stem, the [56] References Cited fuel injection valve being disposed for operative movement in said stem to inject fuel into the combustion UNITED STATES PATENTS chamber when the inlet valve is opened.

878934 2/ 1908 16 Claims, 8 Drawing Figures 1,638,585 8/1927 1,313,608 8/1919 1,602,090 10/1926 2,059,720 11/1936 PATENTEDnEc 5:912

saw u 0F 5 FIG.7

IN VEN TOR PATENTEDHEB i n 3.704.694

SHEET 5 0F 5 IN V EN TOR INTERNAL COMBUSTION ENGINE WITH AN AIR INLET VALVE AND A FUEL INJECTION VALVE This invention relates to an internal combustion engine of the type which employs an air inlet valve and a fuel injection valve, both of which are associated with the combustion chamber of a cylinder and in which the air inlet valve contains a valve body cooperating with a valve seat and supported on a movable valve stem. The features of the invention can be used both in reciprocating internal combustion engines as well as in diesel engines. The invention is intended primarily for use with motors for motor vehicles, but can also be used advantageously in other applications, for example, in connection with stationary engines.

lntemal combustion engines with air inlet valves and fuel injection valves have heretofore been known, for example, in a form where separate such valves have been provided, whereby the air inlet valve has been disposed directly on the cylinder head, while the fuel injection is accomplished in the area of the intake manifold at a location remote from the air inlet valve. Such relative spacing of the valves has the effect of creating a buffer chamber between the place of injection and the entrance of the intake manifold into the combustion chambers of the respective cylinders and may lead to disturbing uncertainties in regard to the actual time of injection, that is to say, the time at which the fuel actually reaches the respective combustion chambers.

In certain special engines and particularly in diesel engines, it has been known to provide for-a direct injec tion of of fuel into the combustion chamber under pressure. This measure, however, is disadvantageous because of the fact that the film of lubricating oil on the cylinder wall of the engine may be washed away by the injected fuel.

An important object of the present invention is the creation of a universally usable internal combustion engine, which will avoid the disadvantages above enumerated of the prior art and which, moreover, will have further advantages, especially in the field of simplified construction and operation. The internal combustion engine, according to the invention, is characterized in that the valve stem of the air inlet valve is hollow and the fuel injection valve and passages have been disposed in it.

In accordance with the invention, therefore, the air inlet valve and the fuel injection valve are combined into a common constructional unit. This offers the advantage that the place of fuel injection and thus the time of injection are clearly defined. The undesirable washing away of lubricating oils and the repeated local impingement of fuel on certain areas of the cylinder and piston will be avoided, especially when, according to the preferred embodiment of the invention, the valve body is disposed inside the combustion chamber and the injection nozzles of the fuel injection valve are provided in an area of the valve stem adjacent to the valve body. In this embodiment, therefore, the valve body, preferably in the form of a valve head, will be disposed within the combustion chamber for cooperation with a seat in an internal wall of the cylinder or the cylinder head, and the injection nozzles, as viewed from the combustion chamber, lie outwardly of the combustion chamber beyond the valve body. The outwardly directed surface of the valve body will be formed to assure a turbulent motion and intermixing of the air and fuel flowing into the combustion chamber. This can be achieved in a relatively simple manner, for example by providing generally spirally arranged swirl surfaces or twisted edges on the upper surface of the valve body, radiating from the valve stem.

The hollow valve stem adjacent to the valve body may be formed with radial ports, between which are disposed angularly spaced sectors of the valve stem, hereinafter sometimes referred to as braces, by which the valve stem is fixedly connected to the valve head. With this arrangement, the inflow of the fuel through the nozzle in the fuel injection valve is free and unimpeded.

The injection valve may contain a nozzle head inserted in fiuidtight sliding relation in the hollow valve stem and having injection nozzles and a locking ram, the latter being operatively movable inside said nozzle head, either to close and isolate the injection nozzles from the fuel supply or to place them in communication with the fuel supply.

Thus, the nozzle head is connected to a valve rod within the valve stem, the valve rod and therefore the head being suitably secured against axial movements, as by connection of the valve rod to a distributor shaft on the cylinder head.

The present invention is distinguished by the fact that a pump chamber for the fuel to be injected as well as a check valve have been disposed between the nozzle head with its injection nozzles and the valve rod within the valve stem, the arrangement being such that the check valve connects the pump chamber with the injection nozzles only during the suction cycle of the engine, and during other operational cycles connects it only with the fuel supply. While the injection of a definite quantity of fuel will be assured by the pump chamber, the provision of the check valves serves the purpose of preventing delivery of fuel into the cylinder by interruption of the connection between the fuel supply on the one hand and the nozzle head on the other.

The pump chamber may be formed within the hollow stem by a radially constricted portion of the nozzle head immediately below its connection with the valve rod.

A particularly advantageous feature of the invention is the arrangement of the cam shaft for adjustment both axially in accordance with the position of the gas control lever and also for angular advance or retardation as may be desirable to adapt to changing loads on the engine. The cams of the cam shaft are formed with cam surfaces which are profiled both axially and circumferentially. This feature offers the possibility of varying the time of the fuel injection, both in accordance with the position of the throttle valve and also in accordance with the load on the engine.

Additional features and advantages of the invention will be apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 presents a diagrammatic sectional view of a portion of a reciprocating internal combustion engine including a portion of the combustion chamber and the intake and fuel injection valves associated therewith, the intake and injection valves both being closed.

FIG. 2 is a cross-section on the line II-II of FIG. 1.

FIG. 3 is a view similar to FIG. 1, but with the intake and injection valves in their open positions during the suction cycle of the combustion chamber.

FIG. 4 is a cross-section on the line IV-IV of FIG. 3.

FIG. 5 is a view similar to FIGS. 1 and 3, but with the valves in the positions which they occupy immediately after conclusion of the suction cycle.

FIG. 6 is a section on the line VI-VI of FIG. 5.

FIG. 7 is a diagrammatic view,"partly in elevation and partly in section, and including the mechanism for operating the valves; and

FIG. 8 is a fragmentary diagrammatic perspective view of the cam shaft of an engine to which the engine is applied and its associated driving and adjusting means.

The structure of the preferred embodiment of the invention given by way of example, will now be explained. The elements of the invention are designated in the various figures by the same reference numerals.

The valve arrangement comprises: The valve stem 1, having an end portion 2 thereof formed with radially directed ports or openings 2a adjacent to the valve body 3, which is in the form of a valve head, and which cooperates with the valve seat 4, which defines an intake port or opening in the cylinder head 5 of the engine. Valve stem 1 is guided for lengthwise movement through a guide sleeve G, affixed to the cylinder head 5 as in FIG. 7. As is shown in FIGS. 1, 3, 5 and 7, the valve stem 1 is hollow and houses therewithin the fuel injection valve, whose primary components are the nozzle head 6, the internally threaded upper portion of which is threaded onto and supported by the lower end of the valve rod 8, the head 6 being formed with a radially constricted or reduced portion or area 7, spaced inwardly from the wall of the tubular stem 1 to form therewith a pump chamber 18 and having radial ports 18a opening from the hollow interior of the nozzle head 6 into the pump chamber 18. It will be noted that the upper end of the hollow nozzle 6 communicates, under the control of the double acting rarn or valve body 10, with the fuel passage 19 through the valve rod 8. The double acting valve body 10 of the check valve is carried by the locking ram 9 which, in turn, is slidably disposed in the nozzle head 6 for movement in an axial direction.

During operation of the engine, when the injection valve is closed, as in FIG. 1, the locking ram 9 has its lower conical end 11 in engagement with a mating conically recessed seat 12 of the nozzle head 6, through which seat the fuel injection nozzles 13 and 13a have been provided for the injection of fuel. When the conical end 11 of the locking ram thus engages the conically recessed seat 12 of the nozzle head, it covers and closes the injection nozzles 13 and 13a. There may be a suitable number of such nozzles which are disposed substantially perpendicularly through the downwardly directed face of the conical seat 12.

When the locking ram 9 is raised from its seated position shown in FIG. 1, to the position shown, for example, in FIG. 3, it uncovers nozzles 13 and 13a to place these nozzles in communication with the

fuel channels

14, 15, 16 and 17, best shown in FIGS. 1 and 2. The result of this is that, as is shown in FIG. 3, the double acting valve body 10 of the check valve will move upwards to close the lower end of the fuel passage 19 and thus disrupt or discontinue the communication between the pump chamber 18 and the fuel line 19. For this purpose, the double acting valve body 10 is acted upon by two relatively

opposed compression springs

20 and 20a, the upper spring 20 of which is stronger than the lower spring 200. Thus, the pressure of the fuel in the line 19, together with over-powering pressure of the spring 20 will normally tend to maintain the double acting valve body 10 and the locking ram 9 in the position shown in FIG. 1 to close the injection nozzles 13 and 13a. However, as soon as the cylindrical pump piston 21, shown in FIG. 1, is moved downwardly with the surrounding valve stem 1 for a sufficient distance, it increases the pressure of fuel within the pump chamber 18 to an amount sufficient to move the valve body 10 upwardly by pressure on the downwardly directed shoulder of its radial flange or projection 23a. The resulting upward movement of valve body 10 carries with it the locking ram 9 to unseat the end 11 of the locking ram from the conical valve seat 12, and to uncover nozzles 13 and 13a. In addition to its main portion 10, the double acting valve body has associated therewith an annular member or portion 22 having a larger external diameter than the adjacent portion of the valve body 10, so that the cylindrical piston 2l which moves with the valve stem 1, controls the operation of the check valve and thus of the injection valve in the preferred embodiment here illustrated. Piston 21 is fixed to the valve stem 1 for axial movement therewith relative to the injection valve 6, which is supported from the fixed valve rod 8 by means of the radially ported and radially constricted upper end portion 7 of the nozzle head 6. The movement of the valve stem 1 and piston 21 is coupled with the operation of the air inlet valve 3.

As indicated in FIG. 3, after uncovering the nozzles 13 and 13a, the fuel flows freely through such nozzles in the form of jets 24 which are directed diagonally downwardly through the ports 2a of the valve stem and through the intake port of the cylinder defined by the valve seat 4 for entrainment in theinflowing air indicated by the arrows 25 in FIG. 3.

The radially constricted and ported section 7 of the nozzle head 6 is shown in cross-section in FIG. 4, wherein the ports 18a open radially outwardly through said section 7 into the pump chamber 18.

The mode of operation of the invention is as follows:

When the intake valve 3 is closed, as in FIG. I, the nozzles 13 and 13a are covered by the locking ram 9 which is in its lowered and seated position so that no fuel can flow through these nozzles. Correspondingly, the double acting ram 10 is also in its lowest position and seated against the member 22 to prevent any backflow of fuel from the fuel channels 14 to 17 as the result of suction or under-pressure occurring in the pumping chamber 18.

When the suction cycle of the cylinder is initiated by the downward movement of the valve stem 1, together with the valve head 3 and cylindrical piston 21, as shown in FIG. 3, then, in consequence of the relatively high pressure occurring in the pumping chamber 18, the enlarged piston like head or flange 23 of the double acting ram 10 is moved upwardly by such pressure counter to the action of the spring 20 and unseated from member 22 to permit flow of fuel from the pump l06009 GI 52 chamber 18 to the fuel channels 14 through 17, and the pressure reliefdmember or valve 22 is moved downwardly by the fuel pressure against the action of spring 20a. The precisely defined quantity of fuel contained in the pumping chamber 18 is delivered through channels 14 through 17 to the nozzles and is sprayed outwardly through the nozzles 13 and 13a as jets 24, as in FIG. 3, both by the compressive action of the cylindrical piston 21 and by the suction within the engine cylinder, the jets of fuel 24 being mixed with the inflowing air 25 by the spirally arranged swirl surfaces 26 to 29, respectively, on the upper or outer face of theintake valve 3.

As soon as the pressure in the pumping chamber 18 is reduced at the completion of the suction cycle and the pump chamber 18 has been emptied, the double acting valve body 10 of the check valve will return to its starting position as shown in FIG. 5, even prior to the closing of the air inlet valve, or, in other words, before the valve head 3 seats against the valve seat 4. Again, therefore, the pumping chamber 18 is connected only with the fuel supply line 19, while its connection with the fuel channels 14 to 17, inclusive, leading to the nozzles 13 and 13a, is interrupted by seating of the valve body 10 on the upper end of the pressure relief valve 22. Thus, the pumping chamber 18 will be filled again with fuel from the fuel passage 19 in readiness for the next suction cycle.

Since the locking ram 9 will also have returned to its seated position, it will be impossible for any fuel retained in the channels 14 to 17 to be discharged through the nozzles 13 and 13a, prior to the next cycle of operation.

FIG. 7 shows diagrammatically a preferred form of actuating means for the valve assembly above described. As mentioned above, valve rod 8, defining therewithin the fuel supply channel 19 extends upwardly through the upper end of the valve stem 1 and is secured to the cylinder head distributor shaft 40, which, in turn, contains a channel 41 through which fuel is delivered under pressure into the supply passage 19 in a manner to avoid the formation of bubbles in the fuel.

For driving the valve stem 1 and the cylinder pump piston 21, there is provided a rocker arm 42 in combination with the valve spring 43 which is compressed between the retainer attachment 44 fixed on the valve stem 1 and the cylinder head 5. The valve spring 43, therefore, resiliently urges the valve stem 1 and the cylindrical pump piston 21 upwardly.

The rocker arm 42, which is suitably fulcrumed at 45, is oscillated angularly about its fulcrum by a cam 46 on rotating cam shaft 81. According to the invention, the cam 46 is movable in two directions, i. e. it is movable in the direction of its axis of rotation, as indicated by the double arrow 47, as determined by the position of the gas lever or throttle, and may be advanced or retarded angularly in its rotation about its axis, as indicated by the double arrow 48, in accordance with the load on the engine. The surface of the cam 46, therefore, is profiled both axially, in the direction of arrows 47 and circumferentially in the direction of arrow 48, (see FIG. 7) and is operatively engaged by the cam follower 49 which, in turn, is connected to the rocker arm 42 at 50 to angularly position the rocker arm in response to the angular and axial movements of the cam 46.

The operation of cam 46 may be achieved in simple manner through

helical gears

83 and 84 employed for transmission of rotation from the crankshaft of the engine to the camshaft 81, as shown diagrammatically in FIG. 8, wherein the camshaft 81 is supported for rotation and for axial shifting movement together with the gear 84 affixed to it. As a result, the required rotary retardation or advancement of the cam 81, in accordance with the load imposed on the engine, may be assured through the use of a servo motor 85 which is responsive to such loading to shift the camshaft 81 accordingly.

More specifically, and as is illustrated in FIG. 8, the crankshaft 80 and the camshaft 81 are interconnected by the two

helical gears

83 and 84. The camshaft 81 is slidable axially in relation to the crankshaft 80 as by means of the servo motor 85, which is controlled in response to loading of the engine, as a result of which, because of the helically arranged interrneshing teeth of the

gears

83 and 84, there is produced a relative angular movement between the said gears which serves to relatively advance or retard the rotary movement of the camshaft 81.

Having thus described our invention, we claim:

1. For use in an internal combustion engine, valve mechanism including an air intake valve comprising a valve head and an elongated, hollow, cylindrical, axially shiftable valve stem connected to the head for shifting the latter between open and closed position in response to axial movement of the stem, and a fuel injection valve disposed within said hollow stem, said fuel injection valve comprising:

a nozzle head structure mounted in said stem for axial movement relative thereto, said structure being disposed in spaced relationship relative to said valve head in a direction axially of the stem to present a hollow space in the stem between the valve head and the structure, there being at least one fuel injection port in said air intake valve intercommunicating said hollow space and the area surrounding the air intake valve,

said nozzle head structure comprising a nozzle head element disposed adjacent said space, a fuel inlet element disposed in axially spaced relationship relative to said head element and means rigidly interconnecting said elements to present a fuel metering chamber having generally fixed dimensions in said stem therebetween,

there being at least one injection nozzle passageway extending through said nozzle head element for normally intercommunicating the space and the chamber and a fuel inlet passageway extending from the fuel inlet element and into the chamber;

rod means connected to said nozzle head structure for holding the same motionless relative to the stem when the latter is shifted axially;

piston means carried by the valve stem and extending into said chamber for reducing the volume of the latter when the valve stem is moved axially relative to the nozzle head structure in a direction to open the air intake valve; and

metering valve mechanism including a double acting valve body mounted in said chamber for movel06009 0153 It.

ment between an injection nozzle passageway closing position and a fuel inlet passageway closing position, there being pressure responsive means on the valve body for moving the latter toward its fuel inlet passageway closing position in response to an increased pressure in said chamber resulting from a reduction of the volume thereof by virtue of the axial movement of the stem in said direction to open the air intake valve, whereby a metered quantity of fuel is discharged through the injection nozzle and said port when the air intake valve is opened.

2. Valve mechanism as set forth in claim 1 wherein is included pressure relief means disposed in said chamber and operable for increasing the volume of the latter in response to the development of an excessive pressure therein.

3. Valve mechanism as set forth in claim ll wherein said port extends through the wall of the valve stem adjacent said valve head.

4. Valve mechanism as set forth in claim 3 wherein the surface of the valve head adjacent said port is characterized by a surface formation in the form of twisted edges shaped to cause thorough mixing of air and fuel.

5. Valve mechanism as set forth in claim 1 wherein said piston means includes a cylindrical piston disposed in surrounding relationship to said fuel inlet element and having an end portion extending into said chamber.

6. Valve mechanism as set forth in claim 5 wherein said injection nozzle passageway and said fuel inlet passageway are generally axially aligned and said double acting valve body is axially elongated and shiftable in an axial direction.

7. Valve mechanism as set forth in claim 6 wherein said nozzle head element includes means presenting a central, axially extending recess extending toward and terminating in communication with said injection nozzle passageway, said double acting valve body including an elongated extension received in said recess, said body and said recess being configured to present at least one axially extending fuel channel therebetween normally intercommunicating said injection nozzle passageway and said chamber.

8. Valve mechanism as set forth in claim 7 wherein is included a plurality of said injection nozzle passageways, the portion of said recess adjacent said passageways being defined by wall means having a conical configuration, said nozzle passageways extending from said adjacent portion of the recess and generally perpendicularly through said wall means.

9. Valve mechanism as set forth in claim 8 wherein the elongated extension of the double acting valve body is provided with a conically configured terminus which is complemental in shape to said portion of the recess adjacent said nozzle passageways whereby the latter with the end of said fuel passageway which opens into the chamber to prevent fuel from entering the chamber.

1 1. Valve mechanism as set forth in claim 10 wherein is included means for yieldably biasing said double acting valve body in an axial direction toward the injection nozzle passageway and away from the end of the fuel inlet passageway, said double acting valve body including an annular abutment adjacent said end element thereof, said abutment being disposed generally in a plane perpendicular to the axis of the stem and facing into said chamber to present said pressure responsive means for forcing said valve body toward the end of the fuel passageway against the bias of the yieldable biasing means when the pressure in the chamber is increased beyond a predetermined level.

12. Valve mechanism as set forth in claim 11 wherein is provided means presenting an enlarged annular space surrounding said recess and communicating with said chamber, there being an annular pressure relief valve element disposed in said annular space in surrounding relationship to said elongated extension and spring means urging said element toward said chamber and into sealed contact with said portion of the valve body, said relief valve element being larger in diameter than said portion and operable to be shifted into the annular space to increase the volume of the chamber when the pressure in the latter exceeds a predetermined level.

13. Valve means as set forth in claim] wherein said engine includes a camshaft mounted for both axial and angular movement and a cam lobe on the camshaft configured to transmit axial movement to a valve stem in operable connection therewith in response to either axial or angular movement of the camshaft, said valve stem being in operable connection with said lobe.

14. Valve means as set forth in claim 1 wherein said engine includes a distributor shaft, said rod means being connected to the distributor shaft and being held thereby to prevent axial movement of the nozzle head structure with the valve stem.

15. Valve mechanism as set forth in claim 1 wherein said rod means and said fuel inlet element are interconnected, said rod means having an axial bore therethrough presenting said inlet fuel passageway.

16. Valve mechanism as set forth in claim 4 wherein said surface comprises helically inclined surface portions.

Claims

1. For use in an internal combustion engine, valve mechanism including an air intake valve comprising a valve head and an elongated, hollow, cylindrical, axially shiftable valve stem connected to the head for shifting the latter between open and closed position in response to axial movement of the stem, and a fuel injection valve disposed within said hollow stem, said fuel injection valve comprising: a nozzle head structure mounted in said stem for axial movement relative thereto, said structure being disposed in spaced relationship relative to said valve head in a direction axially of the stem to present a hollow space in the stem between the valve head and the structure, there being at least one fuel injection port in said air intake valve intercommunicating said hollow space and the area surrounding the air intake valve, said nozzle head structure comprising a nozzle head element disposed adjacent said space, a fuel inlet element disposed in axially spaced relationship relative to said head element and means rigidly interconnecting said elements to present a fuel metering chamber having generally fixed dimensions in said stem therebetween, there being at least one injection nozzle passageway extending through said nozzle head element for normally intercommunicating the space and the chamber and a fuel inlet passageway extending from the fuel inlet element and into the chamber; rod means connected to said nozzle head structure for holding the same motionless relative to the stem when the latter is shifted axially; piston means carried by the valve stem and extending into said chamber for reducing the volume of the latter when the valve stem is moved axially relative to the nozzle head structure in a direction to open the air intake valve; and metering valve mechanism including a double acting valve body mounted in said chamber for movement between an injection nozzle passageway closing position and a fuel inlet passageway closing position, there being pressure responsive means on the valve body for moving the latter toward its fuel inlet passageway closing position in response to an increased pressure in said chamber resulting from a reduction of the volume thereof by virtue of the axial movement of the stem in said direction to open the air intake valve, whereby a metered quantity of fuel is discharged through the injection nozzle and said port when the air intake valve is opened.

3. Valve mechanism as set forth in claim 1 wherein said port extends through the wall of the valve stem adjacent said valve head.

9. Valve mechanism as set forth in claim 8 wherein the elongated extension of the double acting valve body is provided with a conically configured terminus which is complemental in shape to said portion of the recess adjacent said nozzle passageways whereby the latter are closed when said conical terminus iS forced against the wall means defining the conical portion of the recess.

10. Valve mechanism as set forth in claim 7 wherein said double acting valve body includes a portion at the opposite axial end thereof from said extension which is larger in diameter than the latter, said portion including an end element complementally configured to mate with the end of said fuel passageway which opens into the chamber to prevent fuel from entering the chamber.

11. Valve mechanism as set forth in claim 10 wherein is included means for yieldably biasing said double acting valve body in an axial direction toward the injection nozzle passageway and away from the end of the fuel inlet passageway, said double acting valve body including an annular abutment adjacent said end element thereof, said abutment being disposed generally in a plane perpendicular to the axis of the stem and facing into said chamber to present said pressure responsive means for forcing said valve body toward the end of the fuel passageway against the bias of the yieldable biasing means when the pressure in the chamber is increased beyond a predetermined level.

13. Valve means as set forth in claim 1 wherein said engine includes a camshaft mounted for both axial and angular movement and a cam lobe on the camshaft configured to transmit axial movement to a valve stem in operable connection therewith in response to either axial or angular movement of the camshaft, said valve stem being in operable connection with said lobe.