US2430066A - Stroke governor for free piston engines - Google Patents

Description

Nov. 4, 1947. F. M. LEWIS STROKE GOVERNOR FOR FREE PISTON ENGINES Filed Sept. 12, 1945 4 Sheets-Sheet 1 INVENTOR Frank M Lew/'6' ATTORNEYS Nov. 4, 1947. F. M. LEWIS STROKE GOVERNOR FOR FREE PISTON ENGINES Filed Sept. 12, 1945 4 Sheets-Sheet 2 Jru MHZ- 3 FUNK-O Q? INVENTOR Frank M. Zen/1s BY a a 1 ATTORNEYS Nov. 4, 1947.

F. M. LEWIS 2,430,066

STROKE GOVERNOR FOR FREE PISTON ENGINES Filed Sept. 12, 1945 4 Sheets-Sheet 3 FIEr. Es.

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STROKE GOVERNOR FOR FREE PISTON ENGINES Filed Sept. 12, 1945 4 Sheets-Sheet 4 438 an S 1 1 [3:7

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Patented Nov. 4, 1947 STROKE GOVERNOR FOR FREE PISTON ENGINES Frank M. Lewis, Weston, Mass., assignor to General Machinery Corporation, Hamilton, Ohio, a corporation of Delaware Application September 12, 1945, Serial No. 615,731

24 Claims. 1

This invention relates to a stroke governor for free piston engines and more particularly to a device whereby variations in the length of the stroke automatically provide for an increase or decrease in pressure in a bounce chamber to rectify the stroke.

In internal combustion engines of the free piston type, it is customary to provide a bounce chamber wherein air is compressed during working strokes of the engine and this pressure is utilized to return the piston during its combustion stroke. Frequently there are employed two pistons in opposite ends of the combustion chamber and moving in opposite directions. Where this is done the motion synchronized by suitable means which move with or portionately to the pistons.

In accordance with this invention the movement of the pistons is utilized to govern valves for admitting high pressure air into the so-called bounce chamber or to vent air from that chamber in order to adjust the pressure therein so as to obtain a return of the piston to the desired position at the end the compression stroke.

In the accompanying drawings forming a part of this specification,

Fig. 1 is a fragmentary side elevation of a free piston engine equipped with features embodying the invention, with parts broken away; Fig. 2 is a diagrammatic illustration of the feature embodying the invention; Figs. 3 and 4 are diagrammatic detail views showing modifications of the governing cam structure; Fig. 5 is a fragmentary modification of Fig. 2 to include an anti hunting" means; Fig. 6 is a fragmentary detail of a part of the anti "hunting means in Fig. 5, and Fig. 7 is a different form of stroke governor from that shown in Fig. 2.

In the construction shown in Fig. 2 of the drawings, there are indicated a stationary bracket 9 adjacent to racks Ill and II which are in mesh with a pinion i2 so as to move at the same speed in reverse directions. Racks similar to these are frequently connected to the pistons of free piston engines so as to synchronize the movement thereof as indicated in F18. 1.

Rack I0 is provided with a cam surface comprising a depression I3 and a projection ll. These are so positioned on the rack that at the end of the compression stroke they pass beneath a roller IS on the lower end of a. plunger [6 guided by bracket 9. 0n the upper end of plunger Hi there is an adjustable screw il in position to contact one arm of a bell crank lever I8 pivoted at IS, the other arm of the lever being connected by 2 rod 2i to a piston 22. Roller I5 is pressed against the cam surface by a spring 20.

Above the piston 22 there is a cylinder providing chambers 23 and 24 on the opposite sides of a piston 25 which is provided with piston rods 26 extending outward in opposite directions. In the construction shown in the drawings, the right end of piston rod 26 projects near one arm of a bell crank lever 21, the other arm of which is operatively connected to a valve 28. which controls communication between a high pressure air line 29 and a pipe 3|) leading to the bounce chamber. The other rod 26 projects adjacent a bell crank lever 3|, which is operatively connected to a valve 32 controlling communication between pipe 30 and a vent pipe 33.

Piston 22 works in a cylinder providing a chamber 35 on the left of the piston and a chamber 35 on its right. Chamber 35 is connected through a check valve 31 and by-pass 38 to a port 39 into chamber 24, and chamber 36 is similarly connected through check valve 40 and by-pass 4| to a port 12 into chamber 23.

Beneath chambers 35 and 36 there is an accumulator chamber 45. Chamber 4! is connected with chamber 35 through port 48 and through check valve 41 in passage 48. Similarly, chamber 45 is connected to chamber 36 through port 49 and through check valve 50 in passage 5i.

Piston 22 is provided with a plunger rod 52 extending in the opposite direction from rod 2i and working in a pump cylinder 53. Oil is supplied to cylinder 53 from line 54 through check valve 55, and is pumped out through check valve 56 and line 51 into chamber 45.

A cylinder 58 has a piston 59 therein dividing the cylinder into two chambers 60 and 6 I. chamber 60 is in constant communication with chamber .45, while chamber 6| is in constant communicatiorT through line 62 with supply pipe 54. A spring 63 in chamber 6| constantly urges piston 59 to the lft. There is a port 6 in cylinder 58 uncovered by the movement of piston 59 to the right, and opening into line 65 connected to line 52.

The operation of the apparatus shown in Fig. 2 can be readily understood from the foregoing description, but for convenience will be 'summarized as follows:

During the normal operation of the engine, rack III moves to the left until, at the end of the compression stroke, projection i4 is underneath roller l5. It will be readily understood that, when depression I3 passes beneath roller I5, piston 22 moves to the left. During the first part of this movement, oil from chamber 35 flows through port 46 into chamber 45 and thence through port 45 into chamber 36. As the left end of piston 22 covers port 46, the right end uncovers the by-pass 4i, and further movement of piston 22 forces oil past check valve 31 into chamber 24', driving piston 25 and rod 26 to the right, the oil from chamber 23 passing through by-pass 4| into chamber 36. This causes the rod 26 to approach bell crank lever 21, but the apparatus is so arranged that ordinarily the rod will not operate the lever to open valve 28. When the roller l5 rides up on projection M, the reverse action takes place, that is, the initial movement forces oil from chamber 36 through port 49 into chamber 45 and thence through check valve 41 into chamber 35, until port 46 is uncovered, after which the oil passes through that port instead of past the check valve, until port 49 is covered and port 38 uncovered, after which oil is pumped past check valve 40 into chamber 23 and escapes from chamber 24 through by-pass 3B, returning piston 25 to the left. In normal operation this movement of the piston 22 to the light will pum twice as much oil into chamber 23 as the movement of the piston 22 to the left caused by roller l5 dropping into depression [3, pumped into chamber 24, As a matter of illustration. substantially half of the pumping movement of piston 22 as it moves to the right is required to restore piston 25 to its center position while the remaining half of the pumping movement is needed to move piston 25 to the position in which rod 25 is adjacent bell crank lever 3|. When rack moves back to the right, the roller moves downward and piston 22 moves to the left, first forcing oil from chamber 35 through port 46 into chamber 45 and thence past check valve 50 into chamber 35, until port 49 is uncovered, after which the roller again enters depression l3, and by this movement pumps sufficient oil from chamber 35 into chamber 24, so as to return piston 25 to its initial, center position.

It will be seen that pumping action takes place only at the ends of the strokes of piston 22, the beginning and middle part of each stroke not affecting the position of piston 25. Thus, the pumping stroke at one end may be repeated without any intervening pumping stroke at the other end,

It will be seen, therefore, that in normal operation of the device there are two strokes of the piston 22 to the left caused by roller enterins depression 13 on both strokes of the rack, while there is one stroke of the piston 22 to the right far enough to cause pumping action. For normal operation this one pumping action to the right must be sufficient to equal the two pumping strokes to the left.

If it be presumed that the stroke of the piston 22 to the right is sufficient to balance the two strokes to the left when wheel l5 rides up to the point 66 on rojection l4, it will be readily seen that so long as the rack reaches and does not go beyond the point where this occurs there will be no operation of either valve 28 or valve 32. If the stroke is short, and point 66 on cam l4 does not reach a position beneath roller l5, then on each stroke of the engine there is more oil pumped into chamber 24 than is pumped into chamber 23. This difference need not be enough on one stroke of the engine to operate valve 28 but, if the condition is repeated, only a slight failure of the point 66 to reach a desired point under the roller l5 on each stroke will have such cumulative effect that the pistory5 moves to the right until valve 28 is opened, admitting high pressure air to the bounce chamber. This will increase the forces which return the engine pistons during the compression stroke so as to lengthen the stroke and return the operation to normal. Conversely, if cam l4 moves to the left beyond the point where 65 is directly underneath roller [5, there will be an excess of oil pumped into chamber 23 on each stroke of t engine. One occurrence of such an elongated s oke need not be sufficient to open valve 32, but the cumulative effect of continued excessive strokes would quickly move piston 25 to the left far enough to open valve 32 and vent the bounce chamber so as to reduce the pressure therein until the piston was returned only to the normal position at the end of the compression stroke.

On each stroke of piston 22 to the left, the movement of plunger 52 admits oil past check valve 55 into chamber 53, from which it is driven past check valve 56 and through line 51 into chamber 45 by the return of plunger 52 to the right. Thus, a small amount of oil is pumped into the accumulator chamber 45 on each stroke of the engine, and this is more than enough to take care of any normal leakage. As the amount of oil in chamber 45 is increased by the margin that is umped over that which is lost, piston 59 is forced to the right against spring 63 until port 64 is uncovered and allows the excess to escape and to return through lines 65 and 62 to supply pipe 54. Any air trapped in the oil beneath the supply pipe may be vented through a suitable valve such as indicated at 51. Air may be vented from other portions of the oil system through valves 68.

By the described mechanism, it will be seen that control valves 28 and 32 are not operated during the normal running of the engine, even if there is some variation in the length of successive strokes; but if the average of the strokes is even slightly longer or shorter than that for which the device is set, prompt adjustment will follow automatically,

While one construction embodying the invention has been illustrated and described in some detail, it will be readily understood that many modifications are possible by which the features of the invention, as defined in the appended claims, might be utilized. In Figs. 3 and 4, there are shown two slight modifications of the controlling carn. In these figures the cams are shown on the edge of a rack-bar II], as in Fig. 2, but it will be understood that they could be carried by any other part moving in fixed re1ation to the movement of the piston.

In Fig. 3 there is shown a cam rise HI located similarly to the left depression I3 shown in Fig. 2, and an additional cam rise 1| located similarly to rise l4 shown in Fig. 2. The pump and control features are not shown in connection with Fig. 3, as they are the same as shown in Fig. 2. However, the connections must be adjusted so that piston 22 is in its left position when roller l5 rides on the smooth upper surface of bar In, is moved to a middle position when the roller rides up on rise 10, and the first pumping action occurs when the roller rides up on rise H. On the return movement, the riding of roller !5 down rise H returns the piston 22 to a middle position, and the second pumping action occurs as the roller rides clown rise 10. With this arrangement, there are normally only two equal pumping strokes on each reciprocation oi the engine piston, instead of being three strokes, one of which equals the other two, as in the construction disclosed in Fig. 1.

Fig. 4 is similar to Fig. 3 except that it shows one continuous cam rise I3 instead of the separate rises of Fig. 3. The construction shown in Fig. 4 is simpler, and is satisfactory where but little variation in stroke length is likely to occur. However, if there is danger of the stroke shortening so that roller I5 will not ride up on the cam rise 13, the construction shown in Fig. 3 can be adopted and avoid that danger.

In Fig. 1 is diagrammatically illustrated an internal combustion free piston engine having a central cylinder 15, forming the combustion chamber, and opposite end cylinders 16 in which latter air compressor and bounce pistons TI and 18, respectively, operate. A working piston 19 projects inwardly from each set of pistons 11, I8 into said combustion chamber. The fuel injector pump is shown at 80, the fuel or oil pump at El, and the high pressure air supply for the line 29 indicated at 82, and the bounce chamber with which the line 30 connects is shown at 83. A tank for supplying oil to the pump is shown at 84.

In the operation of the governor, piston 25 is caused to move into or out of chambers 23 and 24, depending upon the character of the working strokes. Such movement of piston 25 may, for some applications or conditions, be over sensitive to stroke characteristics, thereby causing the engine to hunt. In Fig. 5 is illustrated an apparatu which acts to dampen the action of the piston 25, whereby its movement is caused to be less responsive to overstroke and understroke conditions, and the objectionable hunting action of the engine is thereby eliminated. In this modification, chambers 23* and 24 and piston 25' correspond to the chambers 23 and 24 and piston 25 in Fig. 3, and the ports 39' and 42' correspond to the ports 39 and 42 of said figure. Provided on the piston rod 26', at each side of the piston 25' adjacent thereto, is a smaller piston 65 that projects through the end wall of the respective chambers 23', 24', and into the respective chambers 96, 81, whereby outward move ments of the pistons 85 in said chambers cause a displacement of fluid therein. The chamber 81 opens through a port 89 into a chamber 89 while the chamber 86 opens through a port 90 into a chamber 9|. The chambers 89 and 9| are separated by a piston valve 92 normally held in neutral position therein by springs 93 at each end. The piston 92 is provided with a central recess 94 adapted by movements of the valve to open communication between one or the other of metering ports 95 and 99 and an exhaust port 91. The ports 95 and 96 communicate, respec tively, with the chambers 24' and 23', while the port 91 communicates with a passage 99 and line 99 leading to an atmospheric pressure relief, such for instance as the oil tank 94 shown in Fig. 1. Relief ports I00 and IOI open, respectively, from the chambers 89 and 9I to the passage 98 and are controlled by needle valves I02. It is preferable in practice to make the metering ports 95 and 96 of slot-form lengthwise of the piston, as shown in Fig. 6, so that a piston movement will uncover an increasing area of one or the other port.

The operation of this damping or hunting" preventing apparatus is as follows: Assuming iston 25' is caused to move in a left-hand direction.

due to an overstroking condition of the power pistons, as previously explained in connection with Fig, 2, the left-hand piston displaces oil from chamber 81 through port 88 into chamber 09. Due tothe close restriction of port I by needle valve I02, the volume of chamber 89 is increased temporarily by the addition of oil and thus the isto valve 92 is caused to compress the opposing balancing spring 93 and to shift in a righthand direction, thereby uncovering the metered orifice 96. Direct communication is thus provided from chamber 23' through the restriction of the orifice 96, lines 91, 9B and 99 to an atmospheric relief. Further pumping of oil by piston 22 (Fig. 2) then will only produce very gradual movement of piston 25' since a relatively large amount of oil will pass through orifice 96. Piston valve 92, due to the balancing action of the springs 93, assumes its neutral location upon the cessation of movement of piston 25'. Such movement of said piston is permitted by the slow escape of oil through the restricted port I00. A return movement of piston 25' is also retarded by the identical action as described above. except only that the device is in operation in the reverse order. Thus, it will be seen that the charging and venting of the direct bounce chamber is dependent on a gradual and controlled movement of piston 25, and that charging and venting are not permitted to follow one another in rapid sequence.

In the modified form of stroke governor shown in Fig, 7, H0 designates a piston synchronizing rack-bar having a cam-raise III thereon, H2 is the roller riding on the rack-bar and cam and carried by a truck H3 having an arm H4 projecting therefrom for the purpose hereinafter described. The truck H3 acts through a pivoted arm H5 against the lower end of a reciprocably movable rod H6 to raise said rod against the tension of a spring III when the roller travels up the cam III. After a predetermined lost motion raising of the rod H6, it strikes the lower end of a rod H8 and causes a raising of a piston H9 in a chamber I20 against the tension of a spring I2I. The chamber I20 at the spring side of the piston has connection with a chamber I22 through a port I23, and at the other side of said piston is in connection with said chamber I22 through a, passage I24 having two ports I25 and I26 opening into the chamber I22. The port. I25 i controlled manually by a needle valve I21 and the port I26 is controlled by a check valve I28, which opens inwardly toward the chamber I20. The chamber I22 has connection with an oil pressure supply source through a line I30 corresponding to the line 54 in Fig. 1. A rod I3I projects from the spring pressed side of the piston H9 and is provided without the chamber I20 with two slots or recesses I32 and I33 spaced longitudinally of the rod. At one side of the rod I3I is a casing I34 having a passage I35 in communication through a line I36, corresponding to line 39 in Fig. 1, with the direct bounce chambers 83 of the engine. This passage has an air pressure supply connection I31 normally closed by a needle valve I38, and also has a pressure relief line I39 to the atmosphere that is controlled by a normally closed needle valve I40. The valves 38 and I40 are opened by movements of respective bell crank levers I4I and I42 having arms projecting freely into the respective slots I33 and I32 for lost motion connection with the rod I3I when moved. The truck arm I I4 is connected by a bell crank lever I43 and connecting rod I44 to a piston I45 in a chamber I45 having connection through a line I" to the scavenging receiver I48 01' the engine. This receiver, as well understood in the art, has air compressed therein by the pistons 11 on their outward strokes and such receiver has connection with the combustion chamber of the engine to supply scavenging air thereto during the engine exhaust period. A spring I49 acts on the piston I45 in opposition to the pressure in the chamber I45.

The operation of this modified form of the in- .vention is as follows: When the engine pistons are near but short of the ends of their compression strokes, the cam III engages roller H2 and raises rod IIB. This movement of rod H6, when its lost motion has been taken up, raises plunger H9, forcing oil from the chamber I20 above the piston into the chamber I22. At the same time oil enters the chamber I20 at the lower side of the piston through the port I26 past non-return valve I28. n the return stroke of the rack III), the plungers H6 and III! lose contact. Plunger I I8 is urged downward by the spring I2 I, but can only return slowly as the oil leaks through controlled orifice I25. The plunger H8 is thus given a small reciprocating motion which will tend to center about a fixed position. If the compression strokes of the engine pistons are normal, the movements of rod I3l and its slots I32 and I33 are such that no motion is imparted to levers Ill and I42 due to their lost motion connection with the rod. Should the engin pistons stop short of their proper compression strokes, roller H2 will not rise as high on cam III as normal. on the subsequent stroke, rod I II! will move down further toward the rod IIB than normal and bell crank lever HI will then be operated to open the valve I38 to admit air pressure from line I31 to passage I35 and consequently to the direct bounce chambers of the engine. Should the pistons I9 have an overstroke condition and come too close together, the cam III will be pushed to the right beyond normal, thus causing a lifting of the roller H2 and raising of the rod I! to actuate the lever I42 to open the vent valve I40, permitting air to be released from the passage I35 and the direct bounce spaces to the atmosphere. Upon an increase in pressure in the scavenging receiver I48 above a normal operating pressure, the piston I45 is moved down in its chamber, thus causing a movement to the left of th truck I I3, so that it will travel a greater distance up the cam III during each compression stroke of the engine pistons. It is thus apparent that the greater the pressure in the scavenging receiver the greater will be the raising movement of the roller H2 and accordingly the piston II! and its rod I3I so as to release pressure from the bounce chambers through the passage I35 until the engine stroke has been lessened in accordance with the increased pressure in the scavenging re ceiver. This arrangement, whereby the position of the cam roller is varied in accordance with the pressure in the scavenging receiver, could be similarly applied to roller I of Fig. 2 as well as to roller II2.

Other variations of cam construction and operation than those shown may be devised and al o mod fications of the pumping device, but the above description makes clear the principle of the control device and will enable those skilled in the art to make such further modifications, within the scope o1 the appended claims, without additional illustration or description.

What I claim is:

1. In an internal combustion engine of the free piston type comprising a bounce chamber and a member moving in fixed relation to the movement of the piston, a free piston stroke control device comprising a source of compressed gas, means providing passages from said source to the bounce chamber and from the chamber to a vent, valve means controlling said passages, and connections from said member operating the valve means when the end of the stroke of the member caused by the compression stroke of the piston is short of its normal position to open the passage from the bounce chamber to said source of compressed gas and when said stroke goes beyond its normal position to open the passage from the bounce chamber to the vent.

2. In an internal combustion engine of the free piston type comprising a bounce chamber and a member moving in fixed relation to the movement of the piston, a free piston stroke control device comprising a source of compressed gas, means providing passages from said source to the bounce chamber and from the chamber to a vent, valve means controlling said passages, a valve operator having a neutral position from which it is movable in one direction to open one of said valves and in the opposite direction to open the other of said valves, and means actuated by repeated short strokes of the engine piston to open the valve controlling the passage from said source to the bounce chamber, and actuated by repeated long strokes of the engine piston to open the valve from the bounce chamber to the vent.

3. Apparatus in accordance with claim 2, and the last said means comprising a pump and a connection from said member actuating said pump at the compression end of the engine stroke.

4. In an internal combustion engine of the free piston type comprising a bounce chamber and a member moving in fixed relation to the movement of the piston, a free piston stroke control device comprising a source of compressed gas, means providing passages from said source to the bounce chamber and from the chamber to a vent, valve means controlling said passages, a cylinder, a piston in the cylinder, connections from the piston operating said valves alternatively when the piston moves in opposite directions, a pump for forcing liquid into said cylinder and moving the piston, and connections from said member operating the pump at the compression end of the engine stroke.

5. Apparatus in accordance, with claim 4, comprising a cam surface carried by said member and operating said connections near, but short of, the compression end of the engine stroke to actuate the pump in the direction to open the valve in the high pressure line and a cam surface carried by said member for actuating the pump in the direction to open the vent valve when said member moves beyond its normal position at the compression end of the engine stroke.

6. In an internal combustion engine of the free piston type having a member moving in fixed relation to the movement of the engine piston, a free piston stroke regulator comprising a pump cylinder and piston and control valves rendering the piston effective for one pumping action when in the latter portion of its movement towards one end of the cylinder and for another pumping action in the latter part of its movement towards the other end of the cylinder, means actuating the pump piston from said member. and means controlled by the pump for lengthening or shortening the stroke of the engine by proportionately greater pumping at one end of the pump cylinder than at the other.

'7. In an internal combustion engine of the free piston type having a member moving in fixed relation to the movement of the engine piston, a free piston stroke regulator comprising a pump cylinder and piston and control valves rendering the piston effective for one pumping action when in the latter portion of its movement towards one end of the cylinder and for another pumping action in the latter part of its movement towards the other end of the cylinder, means actuating the pump piston from said member, and means controlled by said pumping actions for shortening and lengthening the stroke respectively.

8. In an internal combustion engine of the free piston type having a member moving in fixed relation to the movement of the engine piston, a free piston stroke regulator comprising a pump cylinder and piston and control valves rendering the piston effective for one pumping action when in the latter portion of its movement towards one end of the cylinder and for another pumping action in the latter part of its movement towards the other end of the cylinder, a cam surface on said member, a roller in position to be contacted by said surface as the engine piston nears and leaves the end of its compression stroke, and connections from the roller moving the piston in accordance with the movement of the roller.

9. Apparatus in accordance with claim 8 and in which portion of the cam surface first encountered by the roller as the engine piston approaches the end of its compression stroke is' shaped to produce stroke-lengthening action of the pump piston and the portion of the cam surface last encountered by the roller at the end of said compression stroke is shaped to effect stroke-shortening action of the pump.

10. In an internal combustion engine of the free piston type having a bounce chamber compression in which chamber drives the engine piston on its compression free piston stroke, means to govern the stroke at its compressing end comprising a source of gas under high pressure, a valve to connect said source to the bounce chamber, a venting valve for the bounce chamber, a member moving in fixed relation to the movement of the engine piston, a pump, connections from said member to the pump operating the pump variably in accordance with variations in the length of the stroke of the engine piston at the compression end of its stroke, a valve-controlling piston arranged to leave both of said valves closed when the said piston is in an intermediate position and to open the high pressure valve by movement in one direction and to open the vent valve by movement in the other direction, and means to control the position of the valve-controlling piston by the action of the pump and move it in the first said direction when the engine stroke is shorter than desired and in the other direction when the engine stroke is longer than desired.

11. In an internal combustion engine of the free piston type having a bounce chamber compression in which chamber drives the engine piston on its compression free piston stroke and a member moving in fixed relation with the engine piston, stroke-controlling means comprising a pump actuated by said member when said member is at the portion of its movement corresponding to the compression end of the engine stroke and varying the action of the pump in accordance with the length of the stroke, and means governed by the variation in the pumping action to increase the pressure in the bounce chamber when the said stroke is shorter than desired and to decrease the pressure in the bounce chamber when the stroke is longer than desired.

12. In an internal combustion engine of the free piston type having a bounce chamber pressure in which chamber drives the engine piston on its compression free piston stroke and a member moving in fixed relation with the engine piston, a pump cylinder, a piston in the cylinder, and means providing valves and ports for pumping into one outlet only as the piston moves from the middle of the cylinder towards one end thereof and through another outlet only as the piston moves from the middle of the cylinder towards the other end thereof, means operating the piston for pumping action in one end of the cylinder by movement of said member short of the normal end of the compression stroke of the engine and operating the piston for pumping action in the other end of the cylinder to an equal extent at the end of the normal stroke of the member, to a lesser extent when the stroke is short and to a greater extent when the stroke is long, and means actuated by the pumping of liquid from the first said outlet to increase pressure in the bounce chamber and actuated by liquid from the second said outlet to decrease pressure in the bounce chamber.

13. In an internal combustion engine of the free piston type comprising a bounce chamber and a member moving in fixed relation to the movement of the pistons, a free piston stroke con trol device comprising a source of compressed gas, means providing passages from said source to the bounce chamber and from the chamber to a vent, valve means controlling said passages, connections from said member operating the valve means when the end of the stroke of the member caused by the compression stroke of the piston is short of its normal position to open the passage from the bounce chamber to said source of compressed gas and when said stroke goes beyond its normal position to open the passage from the bounce chamber to the vent, and means associated with said connections and operable to dampen the action thereof to prevent hunting of the engine.

14. In an internal combustion engine of the free piston type comprising a bounce chamber and a member moving in fixed relation to the movement of the piston, a free piston stroke control device comprising a source of compressed gas, means providing passages from said source to the bounce chamber and from the chamber to a vent, valve means controlling said passages, a valve operator having a neutral position from which it is movable in one direction to open one of said valves and in the opposite direction to open the other of said valves, means actuated by repeated short strokes of the engine piston to open the valve controlling the passage from said source to the bounce chamber, and actuated by repeated long strokes of the engine piston to open the valve from the bounce chamber to the vent, and hydraulic means operating in connection with said valve operator to dampen its action and eliminate engine hunting,"

15. In an internal combustion engine of the free piston type comprising a bounce chamber and a member moving in fixed relation. to the mowment of the piston, a free piston stroke control device comprising a source of compressed gas, means providing passages from said source to the bounce chamber and from the chamber to a vent, valve means controlling said passages, a cylinder, a piston in the cylinder, connections from the piston operating said valves alternatively when the piston moves in opposite directions, a pump for forcing liquid into said cylinder and moving the piston, connections from said member operating the pump at the compression end of the engine stroke, and hydraulic means in connection with said cylinder operating to dampen the action of said pumped liquid on the piston in the cylinder to eliminate "hunting" of the engine.

16. In an internal combustion engine of the free piston type comprising a bounce chamber and a member moving in fixed relation to the movement of the piston, a free piston stroke control device comprising a source of compressed gas, means providing passages from said source to the bounce chamber and from the chamber to a vent, valve means controlling said passages, a cylinder, a piston in the cylinder, connections from the piston operating said valves alternatively when the piston moves in opposite directions, a pump for forcing liquid into said cylinder and moving the piston, connections from said member operating the pum at the compression end of the engine stroke, and means in connection with said cylinder operable by movement of the piston in said cylinder to effect a metered release of pumped liquid pressure from the cylinder to dampen the action of the liquid on the piston to prevent "hunting" of the eng ne.

17. In an internal combustion engine of the free piston type having a member moving in fixed relation to the movement of its: ngine piston, a free piston stroke regulator comprising a pump cylinder and piston and control valves rendering the piston effective for one pumping action when in the latter portion of its movement towards one end of the cylinder and for another pumping action in the latter part of its movement towards the other end of the cylinder, means actuating the pump piston from said member. means controlled by said pumping actions for shortening and lengthening the stroke respcctively, and means automatically operable to dampen said pumping action on said last means to prevent hunting."

18. In an internal combustion engine of the free piston type having a direct bounce chamber and a member moving in fixed relation to the movement of the engine pistons, a free piston stroke regulator comprising a pump cylinder and a piston therein, said cylinder being open at one side of its piston to a liquid pressure supply source, valve means regulating the communication between said pressure source and the other side of said piston, a spring urging movement of said piston in one direction, means actuating said piston in the other direction from the movement of said member, means in connection with said bounce chamber and having an air pressure supply port and a vent port, and means controlling said ports and operable by movements of said piston to either admit pressure to or vent it from said connection when predetermined running conditions are present in the engine.

19, In an internal combustion engine of the free piston type having a direct bounce chamber, a member moving in fixed relation to the movement of the engine pistons, a free piston stroke rcgulahtir including a connection with said bounce chamber and having a fluid pressure supply port an d a rent port, a normally closed control valve for each of said ports, and means actuated by predetermined overstroke movements of said memher to open said vent valve and hydraulically actuated when understroke movements of the membcr occur to open said pressure supply valve.

20. In an internal combustion engine of the free piston type having a direct bounce chamber, a scavenging pressure receiver and a membi r moving in fixed relation to the movement of the engine pistons, a free piston stroke regulator including a connection with said bounce chamber and having a fluid pressure supply port and a vent port, a normally closed control valve for each oi said ports, means actuated by predetermined overstroke movements of said member to open said vent valve and hydraulically actuated when understroke movements of the member occur to open said pressure supply valve, and means in connection with and operable by scavenging :1 ceiver pressure to vary the extent of member a" tuated movem nt a: s ir first rrran whereby ii creased pressure in said receiver over no: Ina] .ill cause an opening oi 1513. sent vane and m creased pressure thcvein molar n mal will i an Gilt-Di l? -r=. w wip ng- 21. 111 an inte nal combustion engine r 't free piston type having a direct bounce huinber, a scavenging pressure receiver and a mo e her routine, in u n Hi to thi m v menof illc engine n. t an! n. Jib?! having lift ihcr: -n n w. l. 1]; stroke regulamr i *iu' rm; a. noriliaiiy ch 20; valve operable to Matt air pressure to the bounce. chamber, 1mm.

noririaily closed valve operable to permit math}? of air pressure from said chamber, a truck i. L ing movements imparted thereto by said r a. transverse to the member movement at or near a limit of stroke movement of the member means operable by a variance in pressure fro: 1 normal in said receiver to shift the positio i i said truck lengthwise of the member to have an early or late engagement with the cam lift in a compression stroke of the engine pistons, and means controlled by cam actuated movement oi the truck to open said vent valve upon a predetermined over-stroke condition of the engine pistons and controlled at least partially by fluid pressure to open said supply valve upon a predetermined understroke condition of the pistons.

22. In an internal combustion engine of the free piston type comprising a bounce chamber, a bounce chamber, a scavenging pressure receiver and a member moving in fixed relation to the engine piston, tree piston stroke control device comprising a source of compressed gas, means providing a passage from said source to the bounce chamber and a passage from the bounce chamber to a vent, valves controlling said passages, connections from said member opening the valve in the first said passage when the compression stroke of the piston is short of a predetermined normal range, and opening the valve in the second said passage when the compression stroke of the piston is longer than a predetermined normal range, and means predetermining said normal range in accordance with the pressure in said receiver.

23. In an internal combustion engine of the free piston type comprising a bounce chamber, a cavenging pressure receiver and a member moving in fixed relation to the pistonv free piston stroke controlling means comp ising a source increases and to make said range longer as the pressure in the receiver decreases.

24. In an internal combustion engine of the free piston type comprising a bounce member, a scavenging pressure receiver and a member moving in fixed relation to the piston, free piston stroke control device comprising a source of gas under pressure, means providing a passage from said source to said chamber and a passage from said chamber to a vent, a cam on said member, a roller contacted by said cam near the compression end of the piston stroke, connections from said roller opening the first said pas- Patent No. 2,430,066.

14 sage when the cam travels less than a predetermined distance after contacting the roller and opening the vent when the cam travels more than a predetermined distance after contacting the roller, a cylinder, a control piston in the cylinder, means connecting the cylinder on one side of the piston to pressure in the receiver, a spring exerting pressure against the other side of the piston, and connection from the piston to the roller moving the roller to contact the cam earlier as the pressure in the receiver increases and later as the pressure in the receiver decreases.

FRANK M. LEWIS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,083,680 Anderson June 15, 193'? 2,090,709 Steiner Aug. 24, 1937 2,112,368 Janicke Mar. 29, 1946 Certificate of Correction November 4, 1947.

FRANK M. LEWIS It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows: Column 13, line 3, claim 23, and line 16, claim 24, for member read chamber; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Oifice.

Signed and sealed this 30th day of December, A. D. 1947.

THONIAS F. LTURPHY,

Assistant C'ommzsszoner of Patents.

increases and to make said range longer as the pressure in the receiver decreases.

24. In an internal combustion engine of the free piston type comprising a bounce member, a scavenging pressure receiver and a member moving in fixed relation to the piston, free piston stroke control device comprising a source of gas under pressure, means providing a passage from said source to said chamber and a passage from said chamber to a vent, a cam on said member, a roller contacted by said cam near the compression end of the piston stroke, connections from said roller opening the first said pas- Patent No. 2,430,066.

14 sage when the cam travels less than a predetermined distance after contacting the roller and opening the vent when the cam travels more than a predetermined distance after contacting the roller, a cylinder, a control piston in the cylinder, means connecting the cylinder on one side of the piston to pressure in the receiver, a spring exerting pressure against the other side of the piston, and connection from the piston to the roller moving the roller to contact the cam earlier as the pressure in the receiver increases and later as the pressure in the receiver decreases.

FRANK M. LEWIS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,083,680 Anderson June 15, 193'? 2,090,709 Steiner Aug. 24, 1937 2,112,368 Janicke Mar. 29, 1946 Certificate of Correction November 4, 1947.

FRANK M. LEWIS It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows: Column 13, line 3, claim 23, and line 16, claim 24, for member read chamber; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Oifice.

Signed and sealed this 30th day of December, A. D. 1947.

THONIAS F. LTURPHY,

Assistant C'ommzsszoner of Patents.

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