US2699156A

US2699156A - Multiple piston internal-combustion engine

Info

Publication number: US2699156A
Application number: US104072A
Authority: US
Inventors: George F Karow
Original assignee: Individual
Current assignee: Individual
Priority date: 1949-07-11
Filing date: 1949-07-11
Publication date: 1955-01-11
Anticipated expiration: 1972-01-11

Description

4 Sheets-Sheet 1 G. F. KAROW INVENTOR.

. 610x615 ffA xwow MULTIPLE PISTON INTERNAL-COMBUSTION ENGINES Jan. 11, 1955 Filed July 11, L949 WmZu/f .5 m mm ww Jan. 11, 1955 G. F. KAROW MULTIPLE PISTON INTERNAL-COMBUSTION ENGINES Filed July 11, 1949 4 Sheets-Sheet 3 INVENTOR. 6.50 f. KAROW ATTOi/VAYS Jan. 11, 1955 G. F. KAROW 2,699,156

MULTIPLE PISTON INTERNAL-COMBUSTION ENGINES Filed July 11, 1949 4 Sheets-Sheet 4 PI E' 7 United States Patent MULTIPLE PISTON INTERNAL-COMBUSTION ENGINE George F. Kai-ow, Saginaw, Mich.

Application July 11, 1949, Serial No. 104,072

3 Claims. (Cl. 123-51) This invention relates generally to fuel injection systems for internal combustion engines, and refers more particularly to improvements in systems of this type wherein fuel and air are mixed in the proper proportions for ignition within the engine cylinders.

In accordance with this invention air and fuel are introduced into the engine cylinders in timed relation to the operation of the pistons, and are mixed Within the cylinders to provide a combustible fuel mixture. The flow of air into the cylinder is controlled by a throttle valve and the flow of fuel into the cylinder is regulated by a metering valve. The two valves are operated to provide the proportion of fuel and air required to assure the proper fuel mixture for eificient combustion.

It is one of the objects of this invention to admit the air into the cylinder through an annular series of intake ports so closely related to the fuel injector that the fuel and air come in intimate contact as soon as they are discharged into the cylinder.

It is another object of this invention to direct the fuel injector toward the plane including the air inlet ports and to arrange the latter so that the air flows in a spiral path as it enters the cylinder. This construction assures eificient unifiow scavenging of the cylinder and contributes materially in obtaining a homogeneous mixture of the fuel and air in the shortest possible time.

Still another object of this invention is to provide a structure wherein the two valves are normally simultaneously operated by a connection having relatively movable parts enabling movement of the throttle valve relative to the metering valve under the influence of a predetermined air pressure in the supply passage for the air intake ports.

A further object of this invention is to provide means also operated by the air pressure in the supply passage for relatively moving the metering valve and throttle valve to vary the proportion of fuel and air supplied to the cylinder in accordance with variations in the pressure in the air supply passage.

It is still a further object of this invention to open and close communication to the fuel injector with a control valve operated in timed relation to movement of the piston in the cylinder.

The foregoing as well as other objects will be made more apparent as this description proceeds, especially when considered in connection with the accompanying,

drawings, wherein:

Figure 1 is a longitudinal sectional view through a part of an internal combustion engine, and showing the fuel mixture supply system forming the subject matter of this invention;

Figure 2 is a cross sectional view taken substantially on the line 2-2 of Figure 1;

Figure 3 is a sectional view of a part of the fuel mixture control mechanism;

Figure 4 is a cross sectional view taken on the line 44 of Figure 1;

Figure 5 is a fragmentary sectional view taken on the line 5-5 of Figure 1;

Figure 6 is a sectional view taken on the line 66 of Figure 1;

Figure 7 is a fragmentary sectional view showing a modified form of construction; and,

Figure 8 is a sectional view of another embodiment of this invention.

The present invention may be used to advantage in connection with either four-stroke cycle or two-stroke cycle internal combustion engines of the single or doubleacting type having either a single working piston in each cylinder or having opposed working pistons in each cylinder. It will further be understood as this description proceeds that the invention is also applicable to engines employing either the compression ignition principle or some other type of ignition system.

In the embodiment of the invention shown in Figures 1 to 6 inclusive, a two-stroke cycle internal combustion engine is shown of the double-acting type having opposed pistons in each cylinder and having crank or power shafts supported at both ends of the cylinder. The number of cylinders employed may of course be varied to suit the power requirements, and in the present instance, two cylinders are shown in Figure 2 of the drawings as supported in side by side relationship. In engines of the above general type it is customary to conmeet the crankshafts with suitable mechanism designed to operate the crankshafts in timed relationship. This mechanism forms no part of this invention, and is not shown herein.

With the above in view, attention is directed to Figures 1 and 2 of the drawings wherein it will be noted that the numeral 10 designates an engine case having laterally spaced substantially parallel cylinders 11 and having jackets 12; surrounding each cylinder. The purpose of the jackets 12 is to permit cooling the cylinders by circulating a suitable cooling medium through the jackets in heat conducting relation to the cylinder walls.

A pair of pistons 13 and 13 are slidably supported in each cylinder 11 in opposed relationship, and the head portions 14 of the pistons are fashioned to form substantially hemispherical recesses 15 having a diameter approximating three-quarters of the diameter of the piston. The recesses 15 cooperate with one another to provide a combustion chamber 16 when the pistons are in their nearest relative positions, and are formed to register with an ignition device or spark plug 17 supported on the cylinder intermediate the ends thereof. In practice the recesses 15 are olfset with respect to the axes of the pistons to extend as closely as possible to ignition device 17 so that the major charge of fuel mixture contained within the chamber 16 is ignited without delay. In other words the nature of the combustion chamber 16 is such that the charge of fuel mixture is concentrated as much as possible in close proximity to the ignition device 17, so that preignition of a remote charge of fuel mixture by the pressure of the burning charge is omitted. It will further be noted from Figure 1 of the drawings that a pair of crankshafts 18 are respectively journalled on the engine casing 10 at opposite ends of the cylinders, and are respectively connected to the opposed pistons in the cylinders by rods 19;

Since both cylinders are identical in construction, the following description of the cylinder shown in Figure 1 will sufiice for both. In detail an annular series of ports 20 are formed in the side wall of the cylinder 11 adjacent one end of the latter, and are located in a position to be opened and closed by the piston 13. The ports 20 communicate with an annular exhaust passage 21, which in turn, communicates with a suitable exhaust manifold 22.

A second annular series of ports 23 is formed in the side wall of the cylinder 11 adjacent the opposite end thereof and are located in a position to be opened and closed by the piston 13. The ports 23 communicate with an annular intake passage 24, which in turn, communicates with a chamber 25. As shown particularly in Figure 2 of the drawings, the chamber 25 is of sufficient width to accommodate both the cylinders 11. In the present instance air is discharged into the cylinder through the ports 23, and the flow of the air is controlled by a throttle valve 26 secured to a pivot shaft 27. The throttle valve 26 is of the balanced type, and is supported in an extension of the annular air passage 24 in a position to control the flow of air from the chamber 25 to the interior of the cylinder 11.

The pistons in the cylinder 11 are shown in Figure 1 of the drawings in the relative positions they assume as they commence the compression stroke. In detail the piston 13 is in its outermost position wherein the intake ports 23 are fully opened, and the piston 13' is in a somewhat advanced position wherein the exhaust ports 20 are partially closed. The air discharged into the cylinder 11 through the ports 23 serves to force the exhaust gases or products resulting from the previous combustion phase of the cycle out of the cylinder through the ports 20. In this connection attention is again directed to Figure 2 of the drawings, wherein it will be noted that the intake ports 23 are angularly arranged to impart a swirling or spiral motion to the incoming air. This action is highly advantageous in that it assures obtaining greater turbulence and provides a longer path of travel of the air, permitting a longer period of fuel injection without loss through the exhaust ports, and a more complete scavenging of the cylinder is possible.

Owing to the timed relationship between the two pistons, the exhaust ports 20 are closed by the piston 13 prior to closing of the intake ports 23 by the piston 13. During this phase of the operation fuel is injected into the cylinder, and is thoroughly mixed with the incoming air to provide a combustible mixture. The fuel is injected into the cylinder through a suitable nozzle 28 supported on the cylinder 11 in a position with the discharge end communicating with the interior of the cylinder in close proximity to the plane including the annular series of intake ports 23. In fact it will be noted from Figure 1 of the drawings that the nozzle 28 is inclined toward the above plane so that the fuel issuing from the nozzle is immediately brought in intimate relationship to the air flowing into the cylinder through the ports 23. The rate of mixing of the fuel with the air is further enhanced by the swirling action imparted to the air as it passes into the cylinder through the ports 23.

Subsequent to the mixing phase of the cycle, the intake ports 23 are closed by the piston 13, and the fuel mixture is compressed by both pistons into the combustion chamber 16. The compressed combustible fuel mixture is then ignited by the spark plug 17, and is burned in the chamber 16. The shape of the chamber is such as to influence the eflicient burning of the fuel mixture required to obtain maximum performance. As a result of the burning of the fuel mixture within the combustion chamber 16, the pistons in the cylinder 11 are forced outwardly on their power strokes to drive the crankshafts 18 and open both the exhaust and intake ports. The arrangement is such that the exhaust ports 20 are opened slightly in advance of the intake ports in order to reduce the pressure in the cylinder before the scavenging air is admitted to the cylinder.

Supported on the engine casing is a blower or supercharger 30 having a casing 31 and having a pair of rotors 32 respectively secured to shafts 33. The casing 31 has an air intake opening 34 at the top, and an air outlet opening 35 at the bottom which communicates with the interior of the chamber 25. The rotors are provided with intermeshing vanes 36, and opposite sides of the casing are shaped to closely conform to the path of travel of the vanes 36. The shafts 33 are geared together by intermeshing gears 33 and are connected to the power shaft of the engine in a manner not shown herein for rotation by the power shaft at the required speed. Thus air under pressure is supplied to the interior of the cylinders by the blower 30.

The selected fuel is supplied to the nozzle 28 by a tank 37 and a pump unit 38. The unit 38 embodies a gear type pump 39 having intermeshing gears 40 and 41 housed in a chamber 42. The pump chamber 42 is connected to the supply tank 37 by a conduit 43, and also communicates with a discharge passage 44.

The passage 44 or discharge side of the pump 39 is connected to the nozzle 28 by a supply conduit 45 through the medium of a metering device or valve 46 and a combined distributing valve and injection plunger 47. The metering valve 46 embodies a valve member 48 supported for rotation in the unit 38, and has communicating angularly extending passages 49. In the rotative position of the valve member 48 shown in Figure 1, the passages 49 establish communication between the passage 44 leading from the discharge side of the pump 38, and the passage 50, which communicates with the interior of a chamber or bore 51 also formed in the unit 38.

The distributing valve 47 comprises a combined valve member and injection plunger 52 slidably supported in the bore 51 and having an axially extending passage 53 at the outer end thereof. A port 54 is formed in the valve member 52 to connect the passage 50 with the passage 53 in one position of the valve member. A second port 55 is formed in the valve member 52 in a position to register with the conduit 45 in another position of the valve member 52. It follows from the above that the valve 46 serves to meter the flow of fluid from the discharge side of the pump to the distributing valve 47, and the latter serves to supply the metered quantity of fluid to the injector 28. In this connection attention is called to the fact that the passage 44 communicates with the supply tank 37 through a return conduit 57. This conduit is normally closed by a check valve 58, and enables relieving the pressure at the discharge side of the pump when only a limited amount of fuel or fluid is bypassed by the metering valve.

The valve member 52 is also rotatably supported in the bore 51 and is rotated by a driven shaft 59 suitably journalled on the unit 38 and connected to the pump shaft 60 for actuating the pump. A gear 61 is secured to the driven shaft 59, and meshes with a gear 62 secured to the inner end of the valve member 52. The inner face of the gear 62 is formed with a cam 63 having lobes or surfaces spaced from each other around the axis of the valve member 52 and successively engageable with a roller 64 suitably rotatably supported on the unit 38. The cam 63 is yieldably urged into engagement with the roller 64 by a coil spring 65 acting on the outer side of the gear 62.

The above arrangement is such that when the roller 64 is in engagement with the gear 62 between the cam lobes, the port 54 in the member 52 registers with the passage 50 leading from the metering valve 46, and the port 55 in the valve member 52 is closed. Thus the metered fluid flows into the chamber 51 beyond the outer end of the member or plunger 52. It will be understood from the above description that the plunger or member 52 is rotated so that the roller 64 eventually engages the adjacent lobe of the cam 63 and moves the plunger or valve member 52 outwardly closing the intake port 54 and opening the outlet port 55. At the same time the plunger 52 displaces the fuel, previously admitted to the chamber 51 at the outer end of the plunger through the outlet port 55 and supply conduit 45 to the injector 28. It will, of course, be understood that rotation of the valve plunger 52 is timed in relation to the operation of the pistons in the cylinders 11 in order to supply the fuel at the required intervals.

The driven shaft 59 is connected to one of the blower shafts 33 through the medium of a governor 66. The governor 66 has a sleeve 67 supported on the inner end of the driven shaft and having helically extending internal teeth arranged in mesh with correspondingly helically extending external teeth 68 on the inner end of the driven shaft. It will also be noted from Figure 1 of the drawings that the governor embodies a second sleeve 69 having the inner end keyed or otherwise secured to one of the blower shafts 33, and having the outer end telescopically engaging the inner end of the sleeve 67. As shown in Figure 4 of the drawings the outer end of the sleeve 69 is provided with internal splines 70 which mesh with external splines 71 on the sleeve 67. Thus a slidable driving connection is provided between the driven shaft 59 and the associated blower shaft 33.

It will also be noted from Figure 4 that a pair of weights 72 are positioned on diametrically opposite sides of the sleeve 69, and these weights are pivotally connected to the

sleeves

67 and 69 by arms 73 and 73. The arms 73 are secured to or are integral with the weights 72 and are pivoted to the sleeve 69 and the arms 73' are in the form of links having the opposite ends respectively pivoted to the weights and sleeve 67. The weights are normally urged to their innermost positions by suitable coil springs 74 having the opposite ends respectively connected to the weights at opposite sides of the sleeve 69.

The purpose of the governor 66 is to advance the fuel injection timing in relation to the operating cycle of the engine. For example as the speed of the engine increases, the weights 72 are swung outwardly against the action of the springs 74 by centrifugal force, and impart an inward movement to the sleeve 67. Owing to the helically extending intermeshing teeth on the sleeve 67 and shaft 59, the latter is rotated by inward movement of the sleeve 67 in a direction to advance the cams 63 of variations throughout an angular distance proportional to the increase in speed of the engine.

In order to control the st'pply of fuel and air to the cylinders 11, the throttle valve 26 and the metering valve 46 are connected to an operating lever 75. As shown in Figure 3 of the drawings, the operating lever 75 is connected to one end of the metering valve member 43, and the opposite end of the valve member 48 is secured to the link 49'. The free end of the link 49' is connected to: one end of a rod 76 by a fitting 77, and the opposite end of the rod is slidably supported in a bore 78 formed in the adjacent end of a second rod 79. The free end of the rod 79 is connected to a lever 80 by a fitting 81, and the lever 80 is secured to one end of the pivot shaft 27 for the throttle valve 26.

Located intermediate the ends of the connection aforesaid is an expansion unit having a housing 82 comprising

sections

83 and 84. The section 83 has an axially extending hub 85 through which the rod 76 extends, and the outer end of the hub 85 is closed by a plug 86 having a central opening therethrough for slidably receiving the rod 76. The section 84 of the housing 82 is preferably formed integral with the adjacent end of the rod 79, and cooperates with the section 553 to form a chamber 87. The chamber 87 is divided into two

compartments

88 and 89 by a flexible diaphragm 90 having the peripheral portion thereof clamped between the housing sections.

The central portion of the diaphragm 90 is apertured to receive the free end portion of the rod 76, and is clamped to the rod 76 by elements 91. Relative movement of the

rods

76 and 79 is resisted by a coil spring 92 having one end abutting the plug 86 and having the opposite end abutting the adjacent element 91. The plug 86 is preferably threaded in the hub 85 to enable adjusting the compression of the spring 92.

It follows from the above that manipulation of the lever 75 to operate the metering valve 46 imparts a corresponding movement to the throttle valves 26. Such an arrangement is satisfactory as long as the air pressure in the inlet chamber 25 remains the same or substantially so for any preselected throttle valve setting, but unfortunately this is not always the case. In operation the air pressure within the chamber 25 may change as a result in atmospheric conditions (barometric pressure), ambient temperatures and loading conditions of the engine, such as greater cylinder pressure. In accordance with this invention provision is made for automatically adjusting the throttle air valves 26 to compensate for pressure variations in the chamber 25 over a predetermined value determined by the spring 92 and its adjustment.

For accomplishing the above result a fluid connection in the form of a flexible conduit 93 is provided between the chamber 25 and the compartment 89 of the chamber 88. Thus the pressure in the compartment 89 acting on the flexible diaphragm 90 is the same as the air pressure in the chamber 25 so that an increase in the air pressure in the chamber 25 sufficient to overcome the force applied by the spring 92 moves the throttle valves 26 toward their closed positions to correspondingly reduce the quantity of air supplied to the engine cylinders. This movement of the throttle valves 26 is effected without disturbing the setting of the fuel supply valve, so that the optimum fuel-air mixture is assured regardless of pressure variations in the air inlet chamber 25. In this connection it should be noted that the operating lever 75 may be connected to the throttle air valves 26 instead of the fuel control valve, if desired, in which event the fuel control valve 46 would be operated relative to the throttle valves in response to pressure variations in the air inlet chamber 25 to obtain the desired fuel-air mixhere. Also it will be seen that with the above construction, closing of the throttle air valves 26 enables using the engine as a braking means, which is advantageous, particularly when the engine is employed for propelling vehicles. Attention is further directed to the fact that the pressure within the chamber 25 is relieved in the event it exceeds a predetermined maximum value by a pressure relief valve 94 shown in Figure 5 and supported on the chamber 25.

In Figure 7 of the drawings a four-stroke cycle engine is shown having a cylinder 100 closed at the top by a head 101 and having a single working piston 102 slidably supported therein. The head 101 coacts with the top of peratures and engine load variations.

the piston to form a combustion chamber 103, and the spark plug 17 is supported on the head at the center of the combustion chamber 103.

Intake and exhaust ports 104 and 105 respectively are formed in diametrically opposite sides of the cylinder in registration with the combustion chamber 103. The exhaust port communicates with an exhaust manifold 106, and the intake port 104 communicates with an air supply chamber 107. The flow of air from the chamber 107 into the cylinder is controlled by a throttle valve 108 of the balanced type, located in a passage 109 extending between the supply chamber 107 and the port 104. The throttle valve is secured to a pivot shaft 110 having an operating lever 111 secured to one end thereof.

The intake and exhaust ports are controlled by a split sleeve 112 supported for vertical sliding movement be tween the side walls of the piston 102 and the adjacent wall of the cylinder 100. The semi-cylindrical section 114 of the sleeve has a port 113 adapted to register with the intake port 104, and the other semi-cylindrical section has a port 116 positioned to register with the exhaust port 105 in one position of the section 115. The two

sections

114 and 115 are independently operated in timed relation to the operation of the piston to alternately open and close the intake and exhaust ports. The means for operating the semi-cylindrical sections forms no part of the present invention, and is accordingly not shown herein.

The fuel is injected into the combustion chamber 103 by the nozzle 28, and it will be noted that this nozzle is located in close proximity to the intake port 104. It will be understood that the fuel is injected into the combustion chamber 103 in timed relation to opening of the intake port in order to mix with the air flowing from the supply chamber 107 and provide a combustible fuel mixture within the combustion chamber.

The means for supplying the fuel to the injector nozzle 28 in Figure 7 of the drawings is similar in principle of operation to the corresponding means described above with few exceptions. One exception is that the blower 30 is omitted, and air is drawn into the inlet chamber 107 through an appropriate air cleaner not shown herein. Inasmuch as the blower 30 is eliminated, the pump 39 may be driven directly from the engine shafts through a flyweight governor similar to the governor 66 shown in Figure 1 of the drawings. Another exception is the specific construction of the connection between the metering valve operating lever 49, and the throttle valve operating lever 80. In detail this connection comprises a housing 82 having sections 83 and 84' secured together with a flexible diaphragm 90' therebetween. The diaphragm divides the interior of the housing into two compartments 88' and 89'. In the present instance the compartment 88' is sealed to the atmosphere, and is connected to the lever 49' by a part 76. The end Wall of the section 84 is apertured to slidably receive a plunger 79', and this plunger is guided in a sleeve 78 formed in the section 83. The outer end of the plunger is suitably connected to the lever 80, and the intermediate portion of the plunger extends through a central opening formed in the diaphragm 90'.

The plunger 79 is clamped to the central portion of the diaphragm by an enlargement 87 on the plunger at one side of the diaphragm and by a washer 91' slidably supported on the plunger at the opposite side of the diaphragm. The diaphragm is forced to the left by a coil spring 92 having one end abutting the enlargement 87 and having the opposite end abutting the end wall of the section 83. The compression of the spring 92' may be varied by inserting washers of dilferent thicknesses between the end wall of the section 83 and the adjacent end of the spring 92. One of such washers is indicated in Figure 7 by the reference character W.

It has been stated above that the supply chamber 107 communicates with the atmosphere and is connected to the interior of the cylinder above the piston by the passage 109. Thus upon downward movement of the piston in the cylinder, air is drawn from the chamber 107 through the passage 109 into the cylinder and the quantity of the air is determined by the balanced throttle valve 108. As a result of the above operation, a suction is created in the passage 109, and the force of this suction for any given throttle valve setting will, of course, vary depending upon atmospheric conditions, ambient tem- These variations may result in a sufiicient change in the volume of air admitted to the cylinder to disrupt the optimum fuel mixture, and in order to avoid such a condition, the interior of the compartment 88' is connected to the interior of the passage 109 by a conduit 93'.

By reason of the fluid connection 93, the pressure conditions in the passage 109 and in the compartment 88' remain substantially identical. Thus an increase in suction in the compartment 88 above a value determined by the force of the spring 92 effects a relative movement of the parts 76 and 79' toward one another to vary the fuel-air ratio in accordance with the engine operating conditions.

In describing the above embodiment particular stress has been placed on connecting the operating lever 111 to the throttle valve 108. It will, of course, be apparent that the lever 111 may instead be connected to the metering valve 48.

The modification shown in Figure 8 of the drawings illustrates a fuel injection system similar to the one shown in Figures 1 to 6 inclusive as applied to a twostroke cycle engine having a single working piston in each cylinder thereof. In detail it will be noted that an annular series of exhaust ports 120 are formed in the upper end of the cylinder adjacent the head 121, and these ports communicate with an exhaust manifold 122 through the medium of an annular passage 123. A second annular series of ports 124 is formed in the cylinder adjacent the lower end of the latter, and these ports communicate with an air supply chamber 125 through the medium of an annular passage 126. In the present instance the supply chamber 125 communicates with the outlet side of a blower, which is not shown herein, but which may be similar to the blower 30 illustrated in Figure 1 of the drawings. In any case the quantity of air admitted to the intake ports 124 is determined by a throttle valve 131 of the balanced type pivotally supported in the passage 126 between the outlet 131 of the chamber 125 and the intake ports 124.

The fuel is injected into the cylinder immediately adjacent the air intake ports 124 by means of a nozzle 28, and this nozzle is connected to a fuel supply unit which may be identical to the one indicated by the numeral 38 in Figure 1 of the drawings. The throttle valve 131 and the metering valve 46 in the fuel supply unit 38 are preferably interconnected by a connection identical to the one shown in Figure 3 of the drawings, so that the fuel-air ratio is automatically varied in accordance with. changes in engine operating conditions in the manner previously described.

The intake and exhaust ports are controlled by a sleeve 127 supported for vertical sliding movement between the piston and cylinder. The sleeve 127 has an annular series of ports 128 for registration with the exhaust ports 120 in the cylinder, and also has a second series of ports 129 arranged to register with the intake ports 124 also in the cylinder. The ports 129 are actually elongated in the direction of the cylinder axes so that when the sleeve 127 is moved in a downward direction to register the ports 128 with the exhaust ports 120, the top portions of the ports 129 overlap the lower portions of the intake ports 124 to provide for scavenging of the cylinder by the incoming air. The porting is such, however, that when the sleeve 127 is moved upwardly to close the exhaust ports 120, the ports 129 fully register with the intake ports 124. A suitable lug 129 is formed on the lower end of the sleeve, and is connected to suitable mechanism not shown herein for operating the sleeve in timed relation to the movement of the piston in the cylinder.

In accordance with this embodiment of the invention the exhaust ports 120 are opened by the sleeve 127 as the piston approaches its lowermost position in the cylinder. The exhaust ports 120 are opened slightly in advance of opening of the ports 129 by the piston in order to reduce the pressure in the cylinder just prior to admission of the scavenging air. As the piston reaches its lowermost position in the cylinder the scavenging phase of the cycle is completed and the exhaust ports 120 are closed by moving the sleeve 127 upwardly. When the ports are in the above relative positions fuel is injected 8 into the cylinder through the nozzle 28 and the port 130 which is elongated sufiiciently to register with the nozzle 28. This phase continues until the ports 129 are closed by the piston as it moves upwardly on its compression stro e.

From the foregoing description it will be observed that the piston is the controlling factor for the intake ports 124, while the sleeve 127 is the controlling member for the exhaust ports 120. The function of the ports 129 is primarily to provide communication through the sleeve 127, although upward movement of the sleeve valve may be used to provide an additional seal for the intake ports 124 while the piston is traveling upwardly in the top portion of the cylinder. The ports 124 are preferably angularly and tangentially inclined with respect to the cylinder wall to impart a spiral motion to the air.

What I claim as my invention is:

1. An internal combustion engine having a cylinder and having pistons slidably supported in the cylinder in opposed relationship, means for supplying a combustible mixture of gases to the cylinder between the head portions of the pistons, said pistons having generally hemispherically shaped recesses in the head portions registerable with one another in one relative position of the pistons to provide a combustion chamber and being offset relative to the longitudinally extending axes of the pistons to assume positions in close proximity to one side of the cylinder, and an ignition device supported at the said one side of the cylinder in a position to register with the combustion chamber.

2. In an internal combustion engine having a cylinder, first and second members supported in opposed relationship in the cylinder for relative sliding movement and having generally hemispherically shaped recesses registerable with one another in one relative position of the members to provide a combustion chamber, means for supplying a combustible mixture of gases to the cylinder between the members, an ignition device supported at one side of the cylinder in a position to register with the adjacent side of the combustion chamber formed by said recesses in the relative position aforesaid of the members, said recesses being olfset relative to the axis of the cylinder in a direction toward the ignition device and having opposed walls converging toward the side of the cylinder opposite the ignition device to provide said combustion chamber with a quenching area.

3. The structure defined in claim 2 wherein said members comprise pistons slidably supported in the cylinder with the head portions in opposed relationship and wherein said recesses are formed in the head portions of the pistons.

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