US3195526A

US3195526A - Two cycle engine

Info

Publication number: US3195526A
Application number: US359839A
Authority: US
Inventors: Edgar R Jordan
Original assignee: Individual
Current assignee: Individual
Priority date: 1964-04-15
Filing date: 1964-04-15
Publication date: 1965-07-20
Anticipated expiration: 1982-07-20

Description

J y 1955 E. R. JORDAN 3,195,526

TWO CYCLE ENGINE Filed April 15, 1964 2 Sheets-Sheet 1 Iii-l- FUEL LINE INVENTOR. IDEA H.JL7HL7AM.

BY @mg@ .ATTIYE'.

, E. R. JORDAN July 20, 1965 TWO CYCLE ENGINE 2 Sheets-Sheet 2 Filed April 15 1964 INVENTOR: EDGAR H .JUHDAN'.

BY Q a A T T D's.

United States Patent 3,195,526 TWO CYCLE ENGINE Edgar R. Jordan, 1937 Firlawn Drive, Toledo, {)hio Filed Apr. 15, 1964, Ser. No. 359,839 7 Claims. (til. 123- 73) The present invention relates to two cycle engines, and more particularly to a type of two cycle engine in which the fuel air mixture for the engine is introduced directly int-o the engine cylinder and is not drawn into the crankcase of the engine, so that a lubricant does not need to be added to the fuel for the engine.

An object of the present invention is the provision of a new and improved lubrication system for a small two cycle engine which will eliminate the addition of lubricant to the fuel and which still provides adequate lubricationof the bearings of the engine even when the crankshaft extends vertically.

Another object of the invention is the provision of a new and improved two cycle engine having a charge forming chamber that includes a movable wall which, when moved to one end of the chamber, draws a mixture of fuel and air into the charge forming chamber; and when moved to the opposite end of the chamber, forces the fuel-air mixture directly into the combustion chamber of the engine.

Another object of the invention is the provision of a new and improved two cycle engine of the above described type in which there is no mechanical connection between the movable Wall of the charge forming chamber and created in the crankcase as the power piston moves away from the crankcase to its top center position pulls the movable wall to one end of the charge forming chamber to draw a charge of fuel-air mixture into the charge forming chamber, and an increase in crankcase pressure created as the power piston moves to its bottom center position forces the movable wall to the other end of the charge forming chamber to force the fuel-air charge into the combustion chamber.

Another object of the invention is the provision of a new and improved two cycle engine of the above described type having a charge forming chamber with a movable wall therein that is actuated in the above-described manner and which includes automatic means for synchronizing the position of the movable wall relative to the position of the lower piston.

Another object is the provision of a new and improved and inexpensive pressure lubrication system which can be used with the above described two cycle engine structure to provide proper lubrication of the bearings of the engine even though the crankshaft of the engine is normally positioned vertically.

Further objects and advantages of the invention will become apparent to those skilled in the art to which the invention relates from the following description of the preferred embodiment described with reference to the accompanying drawings forming a part of this specification, and in which:

FIG. 1 is a horizontal sectional view through a two cycle engine embodying the present invention; and

FIG. 2 is a vertical sectional view through the center line of the cylinder and crankcase of the engine shown in FIGURE 1. The view includes a lubricating system that is shown in section for claritys sake even though portions or all of the lubricating system would not normally be in the plane through the vertical center line of the cylinder and crankcase.

The two cycle engine shown in the drawings, which represents only a preferred embodiment of the invention, generally comprises a cylinder casting 10 having an integrally east end wall 11 closing off the combustion chamber 12 and a flared opposite end 13 which ends in a flat mating surface 14 to form the top half of a crank case 15. The cylinder casting 10 is made from a light metal, such as aluminum, and may include a cast iron cylinder liner insert 16, and integrally cast cooling fins 17 that extend around its sidewalls 18 and closed end 11. The engine includes a piston 19 received in the liner 16 and which is connected to one end 20 of a connecting rod 21 by a conventional wrist pin 22. The other end 23 of the connecting rod 21 is provided with a bearing 24 for engaging the journal 25 of the crank arm 26 of a crankshaft 27. The end 23 of the connecting rod 21 includes portions 28 which lie on opposite sides of the journal 25 and end in a bolting surface 29 coincident with the major diameter of the journal 25. A bearing cap 30 is positioned over the other half of the journal 25 and is held against the bolting surface 29 by machine screws 31. The bearing surface 24 is shown as being partially formed .by an insert 32 of bearing metal which provides a suitable bearing surface on the region of the bearing surface 24 which transmits the greatest force to the journal 25.

The flared end 13 of the cylinder casting 10 includes opposite sidewall portions 33 and 34 (see FIG. 2) which closely surround one-half of the crankcase chamber 35 and which ends in the flat bolting surface 14 that is coincident with a plane passing through the center line of the journals 37 and 38 (see FIG. 2) of the crankshaft 27 which are positioned on opposite sides of the crank arm 26. The other end of the crankcase chamber 35 is closed off by a casting 39 which has a flat bolting surface 40 for sealing abutment with the bolting surface 14 and which is fastened to the cylinder. casting 10 by bolts, not shown. The casting 39 also closely surrounds the crank arm 26 in its lower position so that the volume of the crankcase chamber 35 is a minimum. The sidewalls of the clyinder casting 10 and liner 16 have an intake open ing 41 therethrough located just above the top of the piston 19 when it is in its bottom center position, and an exhaust port 42 through the liner 16 and casting 10 diametrically opposite the intake opening 41.

According to the invention, the fuel-air mixture that is delivered to the intake opening 41 is supplied from a charging chamber 43 having a movable wall 44 whose displacement generally equals and preferably exceeds the displacement of the power piston 19. The movable Wall 44 separates the charging chamber 43 from an actuating chamber 45 which communicates with the crankcase chamber 35. The charging chamber 43 communicates with a conventional carburetor 46 through a one-way check valve 47 so that as the movable wall 44 moves to expand the charging chamber 43, it draws a fuel-air mixture into the charging chamber, and as the movable wall 44 moves to displace fluid out of the charging chamber 43 and the power piston 19 is below intake opening 41, the fuel-air mixture is forced into the combustion chamber 12. A reduction in pressure in the crankcase 35 and actuating chamber 45 produced by movement of the power piston 19 from its bottom center position to its top center position causes the movable wall 44 to move to a position adjacent the end of the actuating chamber communicating with the crankcase. Movement of the power piston from its top center position toward its bottom center position as well as piston blow-by increases the pressure in the crankcase chamber 35 and actuating chamber 45 to move the movable wall 44 to the opposite end of the housing 48 forming the

chambers

43 and 45. The inertia of the movable wall 44 causes the movable piston-19 so that they will be' in wall to continue movement towards check valve 47 after pressure equalization acrossthe movable wall isachieve'd lypositioni'ng the piston 44 relative to the power piston 19;

to provide a displacement for the movable wall 44 which exceeds that of piston 19.

f In some instances the movable wall 44 can be a diaphragm, and the housing 48 canbe of large diameter so that only a'small amount of movement of the diaphragm is required to produce the ne'ce ssa'r'y displacemerit for adequately charging the combustion chamber'lz with a fuel-air mixture. In the embodiment shown in the drawing, howeventhe'housing 48 forms a cylindrical chain ber 49, andis bolted to the cylinder casting 1t) and cast ing 39 with openings 50 and 51 communicatingwith the intake openingY41 and opening 52 in the crankcase casting 39 respectively. 'The end of the cylinder chamber 49 adjacent .the'openingSI is closed off bya vplug53a se-' cured in place by bolts notjshown. A partition '54'having a plurality of openings .55 'therethrough extends across the cylinder'chamber 49 on theopposite sideoi, the opening 50. The partition54' and openings 55 form" part'of the check valve47, and the closure member for the check valve 47 is formed by'an annular flapper plate 56 that1is held over the openings 55 against the bottom of the partition by a machine screw 57. A dish-shaped stop 58 is positioned. on the'side opposite the flapper plate 56by the screw 57 to. limit inward movement of the.

The carbur'etor'46 is secheck valves formthe phase adjusting means for proper- Assuming that the piston 44 is adjacent the crankcase end of the cylindrical chamber 49 when the power piston 19- is positioned slightly away fromits bottom center 'position,'fand that rotation of the crankshatt 27 in the proper direction causes the power piston 19 to move toward its bottom'center position, therpiston 44 will move only part way toward the partition 54 before the piston 19 reaches its bottom center position. This will cause only a small amount of'gas'es to be' forced out of the charging chamber 43 through the intake opening 41 into the combustion chamber .12; Continuedrotation of the crankshaft 27 causes the power piston 19 to move toward its top center position to reduce the pressure in the crankcase chamber and in turn draw'the charging piston 44 against the plug .53 before theipower piston'19 reaches its top center position.

During movement 'of the charging? piston 44 toward the plug 53, airjis drawnthrough the filter 60 to be mixedwith fuel in the carburetor '46.? The suction created by the ,movement of charging'piston 44 toward the plug 53 creates a pressure dropacross the partition 54'which bends the flapper plate 56 away from the partitionanddraws the fuel-air mixture through the opening 55 into the charging chamber 43. After-the charging piston 44 abuts the plug 53 a further reduction in pressure takes place across the charging piston 44 to move the flapper plate 64away from the charging piston 44 to open opening 63'and draw gases into the crankcase chamber 35 until such time as thepower piston 19 reaches its top center'position to fill the crankcase chamber 35 with gases.

At this time the sparkplug 69 is energized, but because In the embodiment shown in the drawing-the movable wall 441s a cup shaped piston which has a sliding fit with respect to the Walls of the cylinder chamber 49. In order that the drop and rise in pressure created in the crank-1 case can properly actuate the piston,-the piston must have very little friction with respect to the sidewalls of the chamber 49; 'The cylindrical chamber 49vis preferably installed in a horizontalrpo'sition-when, the engine is in its normal running position. Even whenthe cylindrical cham'berj49 is installed in a horizontal position, it'is possible for the piston 44 to slide down the-cylindrical-chamber 49 and assume a position that is'out of phase with the power piston 19. ,It is necessary,theretore, to provide some phase adjusting meansfor periodically adjusting the position of the piston 44 relative to the power proper relationship relativetocachother. r

Movement Ofithe piston 44 toward the end of the chamber connected to thecrankcase is limited by engagementof the piston 44 with the plug 53-. Movement of the piston 44 toward the end of the cylindrical chamber 49 connected .to the carburetor 46 is limited by engage m-ent ofthe piston 44 with the partition 54. If the piston 44 engages the plug 53 beforethe power piston 19 reaches its top center position,,the amount of gas trapped between the

pistons

44 and 19 will beless than normal and the pressure in the crankcase will be reduced below the level which normally exists during outward move- 7 meat ofthe power piston 19. This can be corrected by bleeding additional gas intothe crankcase chamber 35 at this. time, as by a suitable check valve.-; 'The'check valve 62 is formed by a'n opening 63 through the piston 44, and a flapper plate 64 whichcoversthe opening 63 and is held in place byja rivet 65. a 'Conversely,if the piston 44'abuts the "partition 54 before the power-piston reaches its bottom center position,

it is necessary to bleed gas out of the crankcase chamber 35. Outlet check valve 66 is formed by an opening67':

through the piston 44, and a flapper plate 68 is held vover the opening 67 by the rivet 65. The check valves 62 and 66 require a larger pressure differential to be opened than is required to move the piston 44, and together :these only asmall amount of the fuel-air mixture had previously been introduced to. the combustion chamber 12, the mixture therein will probably' not support combustion. Further rotation of the-crankshaft 27 causes the power j piston 19 .1 0 move toward its bottom centerpositio'n to in turn build up pressure in the crankcase chamber 35 which in turn forces thecharg'ing piston toward the partition 54.

The spring action of the flapper plate 56 closes the openings immediately after power piston 19 reaches its top center position, so that movement of the charging piston 44 towards the partition 54 compresses the gases in the charging chamber 43 until such time as the power piston 19 opcns 'intake opening 41. This releases the pressure builtup in the charging chamber 43 so that the charging piston then moves to its position adjacent partition 54 to completely fill the combustion chamber with thefuel-air mixture While also forcing the exhaust gases out through 50,

exhaust-port 42. Continued rotation of thev crankshaft 27 compresses the. fuel-air mixture in the combustion chamber and also draws the charging piston 44 to the opposite end of thecharnber49 to pull afresh charge of fuel-air mixture into the charging chamber 43. When the piston 19 reaches top center position, the: spark plug is energized to ignite the gases. in the combustion chamber 12 to drive power piston-19 toward its bottom center position, andthe process is repeated. V

The; engine so far described prevents. fuel laden gases from entering the crankcase.- The. engine can be mounted with its-crankshaft27 in a'horizontal position in which case the engine can be lubricated by a splash system. The engine shown in the drawings, however, is intended to be' mounted with its crankshaft in a vertical position so-that a pressure type of. lubrication system must be provided to lubricate at least its top bearing 70. As previously stated, itisanobject ofthe invention to provide an inexpensive two cycle engine'including a lubricating system which will be operable with its, crankshaft in alvertical position so that the total structure can be produced at a cost whichis competitive with a four cycle engine in'which oil neednot be added tothetuel. The system comprises an enclosed oil: reservoir 71: which is supplied with pressure from-the'crankcase chamber 35 through a conduit 72 and an outwardly-opening check valve 73. The conduit 72 preferably communicates the lowest point of the crankcase chamber 35 to the reservoir 71, and in the vertical shaft engine shown in the drawings, it communicates with the end of the piston chamber adjacent the end of the piston when the piston 19 is in its bottom center position. An opening 74 is provided through the cylinder casting l0, and the outer end of the opening is enlarged and threaded as at '75 to receive a tubing adapter 76 to receive a flexible tube 77, the other end of which fits over an annular boss '78 on the top of the reservoir 7 1.

Oil is supplied out of the reservoir 71 to the top hearing 70 through an annular outlet tube 79 which is cast into and extends through the top of the reservoir to a point adjacent the bottom of the reservoir. Oil from the outlet tube 79 is communicated to an opening 86 in the bearing 70 and a check valve 81 which is opened by flow to thebearing 79. The check valve 81 is positioned in a stepped opening 82; in the casting 39 which communicates with the opening 80. The outer end of the opening 82 is enlarged and threaded to receive a tube fitting 33, and a length of flexible hose 84 connects the tube fitting 83 with the top end of the outlet tube 79.

Upon movement of the power piston 19 toward its bottom center position, pressure buildup in the crankcase chamber 35 causes oil swept along the bottom of the piston chamber by the piston to be forced out opening 74 through check valve 73 and tubing 7'7 to the oil reservoir 71. This builds up pressure in the oil reservoir 71 during movement of the piston 19 toward the crankcase, and the check valve 73 closes as soon as the piston moves toward its top center position. During movement of the piston 19 toward its top center position, a reduction in pressure is created in the crankcase chamber 35 which causes check valve 81 to open and allow oil to be forced into the top bearing 7% from the reservoir 71 through flexible hose 84. This oil, of course, drains down over the crankcase 27 and connecting rod 21 to lubricate all of the associated bearings and is also thrown by the crank arm into the piston 19 to lubricate the sidewalls of the piston chamber. Oil also runs down to lubricate the lower crankshaft bearing 85. A seal 86 prevents excessive oil leakage out of the bearing 85.

Electricity is supplied to the spark plug 6% by conventional means which includes a wire, not shown, and a magnet, the stator of which is indicated at 87, and the rotor portion of which is carried by the flywheel 88 keyed to the upper end of the crankshaft 27. The stator 87 is bolted to a cup shaped bracket 89 secured to the upper end of the flared end 13 of the casting and the casting 39. An annular dirt seal 90 is positioned around the crankshaft 27 between the upper end of the bearing 70 and bracket 89.

While the indention has been described in considerable detail, it is not intended that it should be limited to the particular embodiment shown and described, and it is desired to cover hereby all novel adaptations, modifications, and arrangements thereof which come within the practice of those skilled in the art to which the invention relates.

What I claim is:

1. In a two cycle engine having a combustion chamber and crankcase separated by a power piston movable between inner and outer positions relative to said combustion chamber, said combustion chamber having an intake port above said outer position of said power piston: a cylindrically shaped fluid displacement chamber one end of which communicates with and is positioned adjacent said intake port of said combustion chamber when said piston is in its outer position and the other end of which is positioned adjacent and communicates with said crankcase, check valve means for communicating flow into said one end of said fluid displacement chamber and preventing return flow therefrom, carburetion means for providing a fuel-air mixture to said check valve means, and a free charging piston in said fluid displacement chamber, said charging piston being movable between a position adjacent said one end of said displacement chamber and a position adjacent the opposite end of said displacement chamber by the alternate decrease and increase in pressure produced in said crankcase during operation of said engine, whereby fuel-air mixture is sucked into said one end of said fluid displacement chamber during inward movement of said power piston and is then forced into said combustion chamber when said power piston is in its outer position without the fuel-air mixture entering said crankcase.

2. In a two cycle engine having a combustion chamber and crankcase separated by a power piston movable between inner and outer positions relative to said combustion chamber, said combustion chamber having an intake port above said outer position of said power piston: a cylindrically shaped fluid displacement chamber one end of which communicates with and is positioned adjacent said intake port of said combustion chamber when said piston is in its outer position and the other end of which is positioned adjacent and communicates with said crankcase, check valve means for communicating flow into said one end of said fluid displacement chamber and preventing return flow therefrom, carburetion means for providing a fuel-air mixture to said check valve means, and a free charging piston in said fluid displacement chamber, said charging piston being movable between a position adjacent said one end of said displacement chamber and a position adjacent the opposite end of said displacement chamber by the alternate increase in pressure and decrease in pressure produced in said crankcase during operation of said engine, valve means for allowing gas to enter said crankcase when said charging piston is in said position adjacent said opposite end of said displacement chamber and said power piston is moving toward but not in its inner position, said valve means having a resistance to opening greater than the force required to move said charging piston, whereby fuel-air mixture is sucked into said one end of said fluid displacement chamber during inward movement of said power piston and is then forced into said combustion chamber when said power piston is in its outer position without the fuel-air mixture entering said crankcase.

3. in a two cycle engine having a combustion cham her and crankcase separated by a power piston movable between inner and outer positions relative to said combustion chamber, said combustion chamber having an intake port above said outer position of said power piston: a cylindrically shaped fluid displacement chamber one end of which communicates with and is positioned adjacent said intake port of said combustion chamber when said piston is in its outer position and the other end of which is positioned adjacent and communicates with said crankcase, check valve means for communicating flow into said one end of said fluid displacement chamber and preventing return flow therefrom, carburetion means for providing a fuel-air mixture to said check valve means, and a free charging piston in said fluid displacement chamber, said charging piston being movable between a position adjacent said one end of said displacement chamber and a position adjacent the opposite end of said displacement chamber by the alternate decrease and increase in pressure produced in said crankcase during operation of said engine, valve means for allowing gas to enter said crankcase when said charging piston is in said position adjacent said opposite end of said displacement chamber and said power piston is moving toward but not in its inner position and valve means for allowing gas to flow out of said crankcase when said charging piston is in said position adjacent said one end of said displacement and said power piston is moving toward but not in its outer position.

4. In a two cycle engine having a combustion chamber and crankcase separated by a power piston movable between inner and outer positions relative to said combustion chamber, said combustion chamber having an intake 'piston'is in its outer position and the other end of which is positioned adjacent and communicates with said crankcase, check valve means for communicating flow into said one end of said fluid displacement chamber and prevent' ing return flow therefrom, carburetion means for pro-"J viding a fuel-air mixture to said check valve means, and a free charging piston wall in said fluid displacement chamber, said charging piston being movable between a position adjacent said one end of said displacement chamber and a position adjacent the opposite end'ofi said dis placement chamber by the alternate decrease and increase in pressure produced in said crankcase during operation of said engine, valve meansin said charging piston for ing a fuel-air mixture to said check valve means, and a free charging piston in said fluid displacement chamber, said charging piston displacing in said chamber a volume at least as great as the displacement of said power piston and being movable between'a position adjacent said one end or" said displacement chamber and a position adjacent the opposite endi of said displacement chamber by the alternate decrease and increase in pressure in said crankcase during'operation of said engine, valve means for piston is in said position adjacent said opposite end of said displacement chamber and said power piston is moving toward but not in its inner position, andrvalve means of said displacement chamber andsaid power piston is allowing gas to enter said crankcase'when said charging a piston is in said position adjacent said opposite end of said displacement chamber and said power piston is movsucked'into said crankcase during inward movement of 20. ing toward but not in its inner position, whereby gas is said powerpiston so that full displacement of said charg- I ing piston occurs when said power outer position. f I a v 5. In a two cycle engine having a combustion chamber and crankcase separated by a power piston movable be piston moves to its tween inner and outer positions relative to said combus'' L tion chamber, said combustion chamber having an intake port above said outer position of said power pistoni a cylindrically shaped fluid displacement chamber one end of which communicates with and is positioncdadjacent said intake port of said combustion chamber'when said piston is in itsrouter position and the other end of which is'positioned adjacent and communicates with said crankcase, check valve means for communicating flow into said one end of said fluid displacementchamber, and preventingreturn flow therefrom, carburetion means for providing a fuel-air mixture to said check valve means,v

and a free charging piston in said .fluid displacement chamber, said charging piston being movable betweenfa position adjacent said one end of said displacement chamber and a position adjacent the oppositeend of said dis-' placement chamber by the alternate decrease and increase in pressure produced in said crankcase during operation of said engine, and phase adjusting means comprising oppositely opening check valves carried by said charging piston and having a resistance to opening greater than" the force required to move said movable wall.

6. In a two cycle engine having a combustion chambet and crankcase separated by a power piston movable between inner and outer positions relative to said combusfor allowing gas to flow out of said crankcase when said charging piston is. in said position adjacent said one end moving toward but not in its outer'position.

7, In a two'cycle engine having a combustion chamber and crankcase separated by a power piston movable between inner and outer positions relative-to said Combustion chamber, said combustion chamber having an intake port above said outer position of said; power piston: a cylindrically shaped fiuid displacement chamber one end of which communicates with and is positioned adjacent said intake port of said combustion chamber when said piston is in its outer position andthe other end of which is positioned adjacent and communicates with said crankcase, check valve means for communicating flow into said one end ofsaid fluid displacement chamber and prevent ing return flow therefrom, an air filter, carburetion means receiving air from said filter and providing a fuel-air mixture to said check vvalve means, and'a charging piston in said fluid displacement chamber, said charging piston having a displacement at least as great as that of said power piston and being movablebetween a'position adjacent 1 said one end of saiddisplacement chamber and a position adjacent the opposite end of said displacementfchamber by the alternate decrease andincrease in pressure produced in said crankcase during operation of said engine, a first check valve in said charging piston for communicating gas to said crankcase from said carburetion means whenv said charging piston is in said position adjacent the opposite end of said displacement chamber and said powerpiston ismoving'toward its inner position, and a second check valve in said charging piston for communicating gas from'said crankcase'to said displacement chamher when said charging piston is in said position adjacent tion chamber, said combustion chamber having an intake;

port above said outer position of said power piston: a cylindrically shaped fluid displacement chamber one'end said intake port of said combustion chamber when said piston is in itsouter position and the other end of which of which communicates with and is positioned adjacent said one end of said displacement chamber and said power piston is moving toward its outer position.

References Cited by theExaminer UNITED STATES PATENTS 821,915 ,5/06 Altham 1846 904,132 11/08' Johnston 134-6 1,453,164 4/23, Newcomb -s 12343 1,606,424 11/26 lngens et al.' 123196 2,745,399 5/56 Heidner et al. V 12373 FOREIGN PATENTS 68,821 9/27 Sweden.

ing return flow therefrom, carburetion means for provid- FRED LENGELTHALER, Primary Examiner.

allowing gas to enter said crankcase when said charging

Claims

1. IN A TWO CYCLE ENGINE HAVING A COMBUSTION CHAMBER AND CRANKCASE SEPARATED BY A POWER PISTON MOVABLE BETWEEN INNER AND OUTER POSITIONS RELATIVE TO SAID COMBUSTION CHAMBER, SAID COMBUSTION CHAMBER HAVING AN INTAKE PORT ABOVE SAID OUTER POSITION OF SAID POWER PISTON: A CYLINDRICALLY SHAPED FLUID DISPLACEMENT CHAMBER ONE END OF WHICH COMMUNICATES WITH AND IS POSITIONED ADJACENT SAID INTAKE PORT OF SAID COMBUSTION CHAMBER WHEN SAID PISTON IS IN ITS OUTER POSITION AND THE OTHER END OF WHICH IS POSITIONED ADJACENT AND COMMUNICATES WITH SAID CRANKCASE, CHECK VALVE MEANS FOR COMMUNICATING FLOW INTO SAID ONE END OF SAID FLUID DISPLACEMENT CHAMBER AND PREVENTING RETURN FLOW THEREFROM, CARBURETION MEANS FOR PROVIDING A FUEL-AIR MIXTURE TO SAID CHECK VALVE MEANS, AND A FREE CHARGING PISTON IN SAID FLUID DISPLACEMENT CHAMBER, SAID CHARGING PISTON BEING MOVABLE BETWEEN A POSITION ADJACENT SAID ONE END OF SAID DISPLACEMENT CHAMBER AND A POSITION ADJACENT THE OPPOSITE END OF SAID DISPLACEMENT CHAMBER BY THE ALTERNATE DECREASE AND INCREASE IN PRESSURE PRODUCED IN SAID CRANKCASE DURING OPERATION