US3071120A - Mechanical starter for freepiston engine - Google Patents

Description

Jan. 1, 1963 R. J. M cRoRY ETAL 3,071,120

MECHANICAL STARTER FQR FREE-PISTON ENGINE Filed July 19, 1960 3 Sheets-Sheet 2 I05 INVEN T0115 ROLLIN J. MCCRQRY ROBERT D. WILSON Jan. 1, 1963 R. .1. MOCRORY ETAL 3,071,120

MECHANICAL STARTER FOR FREE-PISTON ENGINE 3 Sheets-Sheet 3 Filed July 19, 1960 INVENTORS ROLLIN J. McCRORY ROBERT D. WILSON an. e

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This invention relates to a mechanical starting device for a free-piston engine, and, particularly, to a mechanical starting device for a free-piston engine having a pneumatic rebound system or a compressor.

Free-piston engines are those in which the reciprocating motion of the piston, or pistons, is not mechanically restrained by the conventional connecting rod of the crankshaft. Although most of the multipiston freepiston engines have mechanical connections between the pistons to maintain the proper phasing between the pistons, the end positions of the piston stroke are not established by the mechanical connection. The end positions of the piston stroke are established on each engine cycle by the energy released to the work article or load that is being driven by the engine and the energies of the combustion process and the resilient rebound system.

A number of methods and mechanisms have been devised to start free-piston engines. In one example of a conventional mechanism for starting a free-piston engine, the piston is held in starting position by a locking device white the space beneath the piston is pressurized with a fluid; the locking device is released and the pressurized fluid forces the piston rapidly on the compression stroke. There are distinct disadvantages in such a starting device. Usually a second compressor or a storage tank is necessary in such a device for maintaining a supply of high-pressure air which must be available for operation. Where a storage tank is used to supply the air to start the engine, and if the engine does not start immediately, the supply of high-pressure air is soon exhausted. Therefore, a means of replenishing the high-pressure air must be available requiring additional apparatus for the starting mechanism.

This invention includes the steps of first forcing the piston to move in one direction to compress a charge of fluid, suddenly releasing the piston allowing the compressed charge of fluid to move the piston rapidly in the opposite direction on the compression stroke, and repeating the process as often as is necessary until the engine starts.

Briefly described, the apparatus of this invention for a free-piston engine comprises means for moving the piston in one direction to compress a volume of gas and means for releasing the piston to move in the opposite direction on the compression stroke to start the engine.

One of the advantages of this invention is that it is especially usefu for starting a domestic free-piston refrigerator compressor so that it may be made completely automatic in its operation. Another is that supplementary compressor or pressure storage tanks are not required for the operation of the starting mechanism. Still another advantage of the apparatus of this invention is that starting cycles are repeated and no special apparatus is necessary for replenishing the compressed fluid for activating the piston. Also an advantage of this invention is the direct use of the compressor fluid as the starting force.

In the drawings:

FIG. 1 is a sectional elevational view of a free-piston engine and the starting apparatus of this invention;

FIG. 2 is a perspective view, with parts broken away, of the latch carriage of the starting mechanism;

rates Fate dgdiLiZd ice FIG. 3 is a sectional elevational view of the bufier mechanism taken along the lines 3-3 of FIG. 4;

FIG. 4 is a half-sectional elevational view of the buffer; and

FIG. 5 is an elevational view of a starting detection device of this invention.

Referring to FIG. 1, a free-piston engine 11 comprises a block or engine frame 12 and a free-piston 13 reciprocal therein. The engine frame 12 is provided with an internally bored combustion cylinder 14 and provided in communication therewith is a coaxial greater-diameter cylinder 15. Closing the greater-diameter cylinder 15 at the end opposite to the combustion cylinder 14 is a base or mounting plate 16 fastened to mounting blocks 17 by suitable means such as bolts 18. The combustion cylinder 14 is provided with exhaust ports 19 and intake ports 20 at spaced intervals along the cylinder wall thereof. The head end of the combustion cylinder is provided with ignition means 26, such as a spark plug. Centrally positioned on the axis of the combustion cylinder 14 is a fuel nozzle 27 of a fuel injector, designated generally as 23.

As shown in FIG. 1, piston 13 is constructed with a minor diameter portion 2) being sealed with a cylinder wall 25' by means of piston rings 30. At the opposite end, piston 13 is formed in a greater-diameter or flange portion which is adapted to reciprocate in the cylinder 15 and is sealed in connection therewith by means of the piston ring 36. The greater-diameter piston 35 divides the greater-diameter cylinder 15 into a counterchamber 37 and a bounce chamber 38. The counterchamber 37 and the bounce chamber 38 are provided as a pneumatic rebound system to slow, stop, and change the direction of the piston on each stroke. Both the counterchamber 37 and the bounce chamber 38 may be provided with inlet and outlet valves so that the pressure in the chambers may be controlled and thus provide a means for controlling the length of piston stroke and a means for controlling the influence of the pneumatic chambers for varying load conditions.

The free-piston engine 11 shown in FIG. 1 is provided with a piston rod 39 fastened to, or formed integrally with, the piston 13 and adapted to protrude through the base plate to and reciprocate therein through a bushing with a seal The piston rod 39 may be adapted to receive a reciprocating tool or it may be directly connected to a refrigerant compressor.

The frame 12 of the engine 11 is provided with a bore 45 (at an oblique angle in the embodiment shown in FIG. 1) communicating with the outside of the engine it and with the cylinder 37. Bore 45 is provided with a sleeve bearing 46 through which passes a rod 47 sealed with the frame by means of a seal such as seal 48. The rod 47 is free to reciprocate in the bearing 46 occupying a first position where the pusher end 49 is retracted into the bore 46 and a second position where the pusher end 49 contacts or engages the greater diameter piston 35. It is, of course, possible to provide contact of the push rod with the piston 13 through the head end of the compression cylinder 1.4 also, however, the problems of sealing are greatly reduced by providing contact between the push rod and the piston 13 in the cylinder 37 since the pressures in the cylinder 37 do not reach the high peaks that they do in the compression cylinder 14.

The rod 47 is activated by the starting mechanism 5% comprised of two guide frames 51-5L a ball-nut drive mechanism 52, and a latch carriage and control mechanism 53.

Rod 47 is moved in one direction by resilient means such as spring 55 which bears on the frame 12 and the end or head 56 of rod :7. Rod 47 slides in the sleeve 3 bearing 45 and the surface 57 of the head end 56 slides along the surface 55 of the frame 12.

Referring now to FIGS. 1 and 2, the latch es engages the ledge 61 of the head 55 during downward movement of the carria e 53 to force the pusher end 49 against the greater-diameter piston 35 compressing the charge air in bounce chamber and is subsequently disengaged from the head as allowing the rod 47 and piston 1-5 to be moved in the opposite direction by the compressed air. Latch 65 is pivotally mounted on latch plate pin 62 attached to the side plates 53 of the carriage 53. Suitable spacers 6d are provided on the pins 52 and on each side of the latch se to maintain the latch as in centered position between the side plates 63-63. 7

As shown in PEG. 1, the latch 6i") is engaged with the ledge 51 of the push rod head 56. The latch 65 is dis engaged from the rod head 55, pivoting on the pin es in a counterclockwise direction, by means of the linkages d5, 66, and 67. Linkage 55 is pivotally mounted at one end between two projections 65 and 69 of the latch 60 and secured therein by the latch link pin 75. Latch link pin 7% is threaded at each end and held in place by suitable means such as nuts 7.t71 placed against the outside of the projections 63 and as of the latch 65. The opposite end of link 65 is pivotally mounted on cam follower pin 75 which extends through the curved slots ?d76 in the side plates d3-63. Also pivotally mounted by one end on the cam follower pin 75 are the links 66 and 67. At the opposite end links 66 and 67 are pivotally mounted on link pin 77 which is afiixed to the side plate 6363. The linkages 65, 66, and 67 comprise an overcenter device which pivots the latch 65 in a counterclockwise direction jackknifing at the cam follower pin which is free to move in the slot 76. In other words, as the overcenter device is shown in FIGS. 1 and 2, the ends of the pins 7%, 75, and 77 are substantially in a straight line. If a force is exerted against the pin 75, it moves in the slot 76 so that the ends of the pins 70, 75, and 77 are no longer aligned. The distance between pins 76 and 77 is thus reduced and since pin 77 is anchored to the side plates 63 of the carriage 53, pin 79 is pulled downward pivoting the latch 65 counterclockwise on the latch plate pin as. The latched and unlatched position of the latch 60 is maintained by resilient means, such as spring 80, which is attached to the latch so through a hole 81 in the ridge S2. The opposite end of the spring St is attached to a spring mounting pin 83 connected to and suspended between the side plates 63-63. The spring 80 exerts a force on the latch 60 tending to pivot latch 60 counterclockwise. When the links 65, 66, and 57 are in the position shown in FIG. 1, cam follower pin 75 rests against one end of slots 7 s 7e and the end of cam follower pin 75 is slightly to one side of a line extended between the ends of pins 70' and 77. The force exerted on pin 7% by the spring 80 and resistance of the push rod 47 through the latch 60, makes pin 70 tend to approach pin 77 so that cam follower pin 75 is held tightly against one end of slots 76-76. When cam follower pin 75 is pushed from one side of the line extended between the ends of pins 76 and 77 to the other side, cam follower pin 75 is free to move until it rests against the opposite end of the slots 76- 76 where it is again held in place by spring 517.

The latch carriage 53 is mounted on four rollers 9-il-9tl which are mounted on the ends of two axles 9191 rotatably mounted between the side plates 63-65. The rollers 90 roll upon the bottom fiat portion of a U-shaped track 92 which is attached to the side plates 51. The side plates 51 are also provided with channels 93 to receive the tapered ends 94 of the axle 91. e tapered ends 94 which fit into the channel 93 and the guide frame 51 hold the latch carriage to the track 92.

The guide frames 51 are also provided with a cam 95 which is contacted by the cam follower rod 75. On downward movement of the carriage, cam follower rod 75 contacts surface 55 of the cam 95. This forces the rod 75 to move in the slot 76, causing the links 65, 66, and 67 to jackknife and pivot the latch counterclockwise disengaging it from the rod head On upward movement of the carriage the cam follower pin 75 contacts surface 97 of cam which forces the links 65 66, and 67 into substantially a straight line or overcenter position and pivoting the latch es in a clockwise direction to re-engage the push rod head 56.

The latch carriage 53 is moved back and forth along the track 92 by means of the ball-nut drive mechanism 52. The ball-nut drive mechanism is comprised of a motor tiltl which is connected by a series of gears ltil to a ball-bearing nut 162 engaged with a ball-bearing screw 155. Rotation of the ball-bearing nut 15?. moves the ball-bearing screw 153 linearly through the nut in either direction, depending upon the direction of rotation of the ball-bearing nut 185. The ball-nut drive mechanism 52 is pivotally mounted between the guide frames 51 by of pivot trunnions iii-t. The ballbearing screw 153 is connected to a pull rod 1:75 by means of a screw pin 1&6. Pull rod 1%5 is in turn connected to the side plates 6363 of the latch carriage 53 by means of a pin 157 through the end 155 of the pull rod 105. Rotation of the ball-nut drive 52 moves the carriage 53 on the rollers along the track 92. As the carriage 53 moves away from the ball-nut drive 52, the drive 52 pivots counterclockwise on trunnions 154-494 and clockwise on trunnion 164 as the carriage 53 approaches the ball-nut drive 52. The pull rod 155 also pivots correspondingly on pin 157.

A reversing switch located on the latch carriage 53 is activated by switch trip 111 which is a projection of the link 67. As the latch carriage 53 moves toward the ball-nut drive 52 and the cam follower pin 75 contacts surface 96 of cam 95 the links 65, 66, and 67 are jackknifed so that the switch trip 111 on the end of link 67 releases the button 112 on switch 110. Activation of the switch 110 reverses the direction of the motor 100 and consequently the direction of movement of the latch carriage 53. The latch carriage 53 moves away from the drive 52 until the cam follower pin 75 contacts surface 97 of the cam 95 so that the linkages 65, 66, and 67 are forced into a straight line or overcenter position and the switch trip 111 again presses on the button 112. At this time the latch 66 engages the rod head 56, the motor 150 is reversed and the carriage 53 moves in the opposite direction forcing the pusher end 4) to bear upon and move the piston 13.

When the rod 47 is released by the latch 60, the pocket of compressed fluid forces the piston 13 and the rod 47 rapidly in the opposite direction. For this reason, a buffer is provided to stop and retain the rod 47 after it has been returned by the piston 13.

Referring to FIGS. 3 and 4, the buffer 125 is provided with a mounting bracket 121 which may be secured, for example, to the engine frame 12 by suitable means such as bolts 112. A block 123 and plate 124 are secured to the bracket 121 by bolts 125. A resilient body or shock absorber 126, preferably of rubber, is suspended between the plate 124 and the bracket 121 held in place by a bolt 127 and centered by means of spacers 128. A second metal block rests on top of the shock absorber 126 having inclined surfaces or sides 136. Leaf springs 137 and 155 are attached by bolts 139 to the tapered sides 136 of the block 135. The inner faces of leaf springs 157 and 135 are provided with a brake lining 145. The ends of leaf springs 137 and 138 are provided with latch surfaces 141 and 142 and tapered ends 143 and 144. At

the edges of the leaf springs 157 and 15-5, at the point where the latch es passes between the leaf springs 137 and 138 to engage the surface 61 of the rod head 56, a wedge or inclined plane 145 is provided for disengaging the latch surfaces 141 and 142 from the rod head 56.

When the rod 47 is thrown toward the buffer 120 by movement of the piston 13 and the resilient force of spring 55, the rod head 56 contacts the inclined surfaces 143 and 144 of the leaf springs 137 and 138. Since the leaf springs 137 and 138 are attached to the inclined surface 136 of the block 135, the tapered ends 141 and 142 approach each other in the relaxed position. The rod head 56 striking the inclined surfaces 143 and 144- forces the leaf springs 137 and 138 apart so that the head 56 is driven between the springs 137 and 13S and strikes the shock absorber 1%. Rod head 56 continues in the same direction until the force of its energy is absorbed by the shock absorber 126. The rod 47 is then rebounded in the opposite direction but by this time the leaf springs 137 and 138 have snapped toward each other so that the brake surfaces 140 bear upon the rod head 56 slowing its move ment in the opposite direction. The rod head 56 is then contacted by the latch surfaces 141 and 142. This tends to pull the leaf springs 137 and 138 in the direction of the movement of the rod 47. Since the leaf springs 137 and 138 are attached to block 135, the block 135 is pulled against the end of shock absorber 126 which is opposite the end that is first struck by the rod head 56. Thus, the force of the rod 47 is dissipated by reciprocation in the buffer with forces applied at both ends of the shock absorber 126.

When the red head 56 is re-engaged by the latch 60, the nose 146 of the latch 61 presses upon the triangularly shaped pieces or inclined planes 145145 attached to the leaf springs 137 and 138. When the latch is rotated clockwise, the leaf springs 137 and 138 are forced apart as the nose 146 of the latch 60 is forced between the Wedges or inclined planes 145-145 disengaging the latching surfaces 141 and 142 from the rod head 56. The rod 47 is now available to again force the piston 13 in a direction to compress a charge of fluid.

The starting device may be made operationally responsive to a thermostat as, for example, in a domestic refrigerating apparatus. Means are also provided to deactivate the starting mechanism upon the engine starting. This may be done, for example, by means of the starting detection device shown in FIG. 5. A plate 1613 is placed at the exhaust outlet 161 of the engine so that the exhaust gases will strike and push upon the plate 161?. The plate 16% is mounted on a rod 162 which is pivotally mounted by suitable means such as a pin 163 and a pillow block 154. A normally closed switch 165 is provided with a switch button 166 so that when the switch 165 is connected in series with the motor 100 of the ball-nut drive mechanism 52, exhaust gases push upon the plate 16%) so that the rod 162 is forced against the button 166 to open the switch, thus stopping the action of the starting mechanism.

When the free-piston engine 11 is connected to a compressor, the fluid or gas in a compression chamber may be used to activate the piston in one direction when compressed by action of the rod 47 instead of the fluid in the bounce chamber 38.

It will be understood, of course, that, while the forms of the invention herein shown and described, constitute preferred embodiments of the invention, it is not intended to illustrate all possible forms of the invention. It will also be understood that the words used are words of description rather than words of limitation and that various changes, such as changes in shape, size, and arrangement of parts may be made without departing from the spirit and scope of the invention herein disclosed.

What is claimed is:

1. In a free-piston engine a starting device, comprising: means, reciprocable in said device, positioned for contacting the piston of said engine and for releasing said piston on each reciprocation; engagement means for engaging said contacting means moving said piston compressing a volume of gas; means to disengage said engagement means from said contacting means releasing said piston and allowing the compressed volume of gas to move said piston on the compression stroke of said engine; and means for arresting movement of said contacting means and preventing said contacting means from contacting said piston after said piston is released and said engine has started.

2. In a free-piston engine, a starting device, comprising: a rod, reciprocable in said engine, positioned to engage and disengage the piston of said engine on each reciprocation; a latch, attached to reciprocating drive means positioned to engage and move said rod moving said piston to compress a volume of gas and to disengage said rod after said volume of gas is compressed allowing the compressed gas to move said piston on the compression stroke of said engine; and means for arresting movement of said rod and preventing said rod from enga ing said piston after said piston is released and said engine has started.

3. In a free-piston engine, a starting device, comprising: a rod, extending through the engine frame reciprocable therein, positioned to engage and disengage the piston of said engine on each reciprocation; a guide frame, adjacent to said engine frame; a carriage supported by said guide frame and reciprocable thereon; and a latch, pivotally supported by said carriage, positioned to engage said rod and move said piston to compress a volume of gas on one direction of carriage reciprocation, and to disengage said rod allowing the compressed gas to move said piston on the compression stroke of said engine on the opposite direction of reciprocation.

4. In a free-piston engine, a starting device, comprising: a rod, extending through the engine frame, including a pusher end and a head end, said pusher end positioned within said engine frame in a first position of said rod, said pusher end engaging the piston of said engine in a second position of said rod; a guide frame, adjacent to said engine frame, having a track parallel to the long axis of said rod; a carriag supported by said guide frame and free to reciprocate on said track; a latch pivotally supported by said carriage positioned to engage said head end of said rod in said first position, to maintain engagement with said head end during movement of said carriage and said rod through said second position, and to disengage said head end of said rod after said rod has pushed said piston to compress avolume of gas; means supported by said carriage and attached to said latch, responsive to reciprocation of said carriage, for pivoting said latch to disengage and engage said head end of said rod; power means to impart reciprocating movement to said carriage; and a buffer positioned to arrest movement of said rod after said rod is thrown to said first position by said piston.

5. In a free-piston engine, a starting device, comprising: a rod, free to reciprocate in a bore in the engine frame, said rod including a pusher end and a head end, said pusher end positioned within said bore in said engine frame in a first position, said pusher end. engaging the piston of said engine in a second position, and said head end external to said engine frame in said first and second positions; a guide frame, adjacent to said engine frame, having a track; a carriage supported by said guide frame and free to reciprocate on said track; a latch pivotally supported by said carriage positioned to engage said head end of said rod in said first position, to maintain engagement with said head end during movement of said carriage and said rod through said second position, and to disengage said head end of said rod after said rod has pushed said piston to compress a volume of gas; means supported by said carriage and attached to said latch pivoting said latch to disengage and engage said head end of said rod upon reciprocation of said carriage; power means to impart reciprocating movement to said carriage; a buffer positioned to receive the impact of said head end of said rod and arrest movement of said rod after said rod is thrown to said first position by said piston; and means s for deactivating said power means when said engine is operating.

6. In a free-piston engine having a pneumatic rebound system, a starting device, comprising: a rod, free to reciprocate in a bore in the engine frame, said rod including a pusher end and a head end, said pusher end positioned Within said bor in said engine frame in a first position, said pusher end engaging the piston of said engine in a second position, and said head end external to said engine frame in said first and second positions; a guide frame, adjacent to said engine frame, including a cam and a track; a carriage supported by said guide frame and free to move on said track; a latch pivotally supported by said carriage positioned to engage said head end of said rod in said first position, to maintain engagement with said head end during movement of said carriage and said rod through said second position, and to disengage said head end of said rod after said rod has pushed said piston to compress a volume of gas; an overcenter linkage supported by said carriage and attached to said latch, said overcenter linkage including a cam follower to engage said cam on said guide frame and on movement of said carriage to jackknife and straighten said overcenter linkage pivoting said latch to disengage and engage said head end of said rod; power means to impart reciprocating movement to said carriage; and a buffer positioned to arrest movement of said rod after said rod is thrown to said first position.

7. In a free-piston engine having a piston with a flange, 21 starting device, comprising: a rod, free to reciprocate in a bore in the engine frame, said rod including a pusher end and a head end, said pusher end positioned within said bore in said engine frame in a first position, said pusher end engaging said flange of said piston in a second position, and said head end external to said engine frame in said first and second positions; a guide frame, adjacent to said engine frame, including a cam and a track parallel to the long axis of said rod; a carriage supported by said guide frame and free to move on said track; a. latch pivotally supported by said carriage positioned to engage said head end of said rod in said first position, to maintain engagement with said head end during movement of said carriage and said rod through said second position, and to disengage said head end of said rod after said rod ha pushed said piston to compress a volume of gas; an overcenter linkage supported by said carriage and attached to said latch, said overcenter linkage including a cam follower to engage said cam on said guide frame and on movement of said carriage to jackknife and straighten said overcenter linkage pivoting said latch to disengage and engage said head end of said rod; power means to impart reciprocating movement to said carriage; and a buffer positioned to receiv the impact of said head end of said rod and arrest movement of said rod after said rod is thrown to said first position by said piston and to engage said head end of said rod preventing said rod from returning to said second position.

8. In a free-piston-engine compressor having a piston with a flange, a starting device, comprising: a rod, free to reciprocate in a bore in the engine frame, said rod including a pusher end and a head end, said pusher end positioned within said bore in said engine frame in a first position, said pusher end engaging said flange of said piston in a second position, and said head end external to said engine framein said first and second positions; a guide frame, adjacent to said engine frame, including a cam and a track parallel to the long axis of said rod; a carriage supported by said guide frame and free to move on said track; a latch pivotally supported by said carriage positioned to engage said head end of said rod in said first position, to maintain engagement with said head end during movement of said carriage and said rod through said second position, and to disengage said head end of said rod after said rod has pushed said piston to compress a volume of gas; an overcenter linkage supported by said carriage and attached to said latch, said overcenter linkage including acam follower to engage said cam on said guide frame and on movement of said carriage to jackknife and straighten said overcenter linkage pivoting said latch to disengage and engage said head end of said rod; a ball-nut drive including power means to impart reciprocating movement to said carriage; a buffer including a resilient body and spring clips, said resilient body positioned to receive the impact of said head end of said rod and arrest movement of said rod after said rod is thrown to said first position by said piston and said spring clips positioned to engage said head end of said rod preventing said rod from returning to said second position; and combustlon detection means for deactivating said power means when said engine starts.

9. In a free-piston-engine compressor having a unitary piston with a flange, a startingdevice, comprising: a rod, free to reciprocate longitudinally in an oblique bore in the engine frame, said rod including a pusher end and a head end, said pusher end positioned within said bore in said engine frame in a first position, said pusher end engaging said flange of said piston in a second position, and said head end external to said engine frame in said first and second positions; a guide frame, adjacent to said engine frame, including a cam and a track parallel to the long axis of said rod; a carriage supported by said guide frame and free to move on said track; a latch pivotally supported by said carriage positioned to engage said head end of said rod in said first position, to maintain engagement with said head end during movement of said carriage and said rod through said second position, and to disengage said head end of said rod after said rod has pushed said piston to compress a volume of gas; an overcenter linkage supported by said carriage and attached to said latch, said overcenter linkage including a cam follower to engage said cam on said guide frame and on movement of said carriage to jackknife and straighten said overcenter linkage pivoting said latch to disengage and engage said head end of said rod; a ball-nut drive including power means to impart reciprocating movement to said carriage; a buffer including a resilient body and spring clips, said resilient body positioned to receive the impact of said head end of said rod and arrest movement of said rod after said rod is thrown to said first position by said piston and said spring clips positioned to engage said head end of said rod preventing said rod from returning to said second position; and combustion detection means including a plate positioned for deflection by said'exhaust gas, said plate opening a switch on deflection to deactivate said power means.

References flirted in the file of this patent UNITED STATES PATENTS 2,795,927 Huber June 18, 1957 2,867,374 Petersen June 6, 1959 2,943,438 Huber July 5, 1960 FOREIGN PATENTS 353,587 Germany May 22, 1922 330,574 Great Britain June 11, 1930 659,428 Great Britain Oct. 24, 1951

Claims (1)

1. IN A FREE-PISTON ENGINE A STARTING DEVICE, COMPRISING: MEANS, RECIPROCABLE IN SAID DEVICE, POSITIONED FOR CONTACTING THE PISTON OF SAID ENGINE AND FOR RELEASING SAID PISTON ON EACH RECIPROCATION; ENGAGEMENT MEANS FOR ENGAGING SAID CONTACTING MEANS MOVING SAID PISTON COMPRESSING A VOLUME OF GAS; MEANS TO DISENGAGE SAID ENGAGEMENT MEANS FROM SAID CONTACTING MEANS RELEASING SAID PISTON AND ALLOWING THE COMPRESSED VOLUME OF GAS TO MOVE SAID PISTON ON THE COMPRESSION STROKE OF SAID ENGINE; AND MEANS FOR ARRESTING MOVEMENT OF SAID CONTACTING MEANS AND PREVENTING SAID CONTACTING MEANS FROM CONTACTING SAID PISTON AFTER SAID PISTON IS RELEASED AND SAID ENGINE HAS STARTED.

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