US3600886A

US3600886A - Hot gas engine

Info

Publication number: US3600886A
Application number: US855170A
Authority: US
Inventors: Hendrik Alphons Jaspers; Gregorius Theodorus Mar Neelen
Original assignee: US Philips Corp
Current assignee: US Philips Corp
Priority date: 1968-09-07
Filing date: 1969-09-04
Publication date: 1971-08-24
Anticipated expiration: 1988-08-24
Also published as: BE738502A; DE1942230A1; NL148378B; FR2017586A1; DE1942230C3; CH523424A; FI52620B; DE1942230B2; NL6812816A; SE351702B; AT297414B; FI52620C; DK130026C; NO124651B; ES371242A1; GB1288224A; DK130026B

Abstract

A hot gas engine having a buffer space, a working space in communication with a medium supply duct including a controllable inlet valve, a medium outlet duct including a controllable exhaust cock, a communication duct including a bypass valve between the working space and buffer space, a first control device which is movable against the action of a spring for operating the inlet and exhaust valves, and a second control device which is movable against the action of the spring for operating the bypass valve, the control devices being constructed so that during normal operation a movement of the second control device is associated with the same movement of the first control device, while upon braking with the engine the bypass valve is maximally opened and by moving the first control device only the inlet cock can be opened to provide a maximum braking torque.

Description

United States Patent 1 3,600,886

[72] inventors Hendrik Alphons .laspers; Primary ExaminerMartin P. Schwadron Gregorlus Theodorus Marla Neelen, both of Assistant Examiner-A. M. Zupcic Emmasingel, Eindhoven, Netherland Alromey Frank R. Trifari [2i App]. No. 855,170

22; Filed Sept. 4, 1969 [45] Patented Aug. 24, 1971 [73] Assignee U.S. Philips Corporation 32 1 Priority ABSTRACT: A hot gas engine having a buffer space, a work- I I ing space in communication with a medium supply duct in- [33] N cluding a controllable inlet valve, a medium outlet duct in- [N M2816 cluding a controllable exhaust cock, a communication duct including a bypass valve between the working space and buffer [54] HOT GAS ENGINE space, a first control device which is movable against the acu Cum 4 Dn'tng Ft tion of a spring for operating the inlet and exhaust valves, and

a second control device which is movable against the action of [52] US. Cl. 60/24, 62/6 the spring for operating the bypass vahe the control devices [51] CL 9/00 being constructed so that during normal operation a movel Field snub 60/24; 62/6 ment of the second control device is associated with the same movement of the first control device, while upon braking with [56] References the engine the bypass valve is maximally opened and by mov- UNITED STATES PATENTS ing the first control device only the inlet cock can be opened 3,466,867 9/1969 Brandes 60/24 to provide a maximum braking torque.

, 5 N -11" .l]I'- r n v A 2 27 28 I 12| I 1. as 31. 3s 33 23 PATENTED mm m.

SHKET 1 OF 3 INVENTORS HENDRIK A. PERS GREGORIUS M.NEELEN BY AGEN 1 1 one INVENTORS HENDRIK AJASPERS GREGORIUS T. M.NEELEN PATENTEU M1824 l9?! SHEET .3 OF 3 INVENTORS HENDRIK A. JASPERS GREGORIUS T- M.NEELEN BY A AGENT HOT GAS ENGINE The invention relates to a hot gas engine comprising one or more working spaces each of which communicates, if desirable through a nonreturn valve permitting flow in the direction of the respective working space, with a medium inlet duct comprising a controllable suppletion or inlet cock and in which furthermore each working space communicates if desirable through a nonreturn valve opposing flow of medium in the direction of the respective working space, with a medium outlet duct, the removal of medium through said duct being controlled by a controllable exhaust cock and furthermore either a communication duct being provided between each working space and a buffer space containing the same medium as the working space, or a communication duct is present between the medium inlet and medium outlet duct, a bypass-closing member being present in said communication duct(s) which is continuously controllable between its closed position and its fully open position.

It is known to control the supplied power of hot gas engines by varying the average pressure in the working space. Increase of the supplied torque is achieved by temporarily opening the suppletion or inlet cock in the medium supply duct as a result of which working medium flows from a storage container into the working space(s) of the engine and the average pressure level increases. On the other hand, reduction of the torque supplied by the engine can be achieved by temporarily opening the exhaust cock, as a result of which working medium is pumped back from the working space to the storage container, for example, by means of a compressor. Since for structural reasons the dimensions of the compressor may not be unduly large, the removal of working medium will occur only comparatively slowly. A rapid reduction of torque can be obtained by opening, in addition to the exhaust cock, a bypass valve in a communication duct between the working space and a buffer space in which the same medium is present as in the working space or in a communication duct between the medium inlet and medium outlet duct. As a result of this such a distortion of the pressure-volume diagram is obtained that a rapid reduction of the supplied torque occurs. This is based on the fact that due to the flow losses occurring in the bypass valve the phase difference between the volume and pressure variations occurring in the cold and warm spaces, respectively, of the engine begins to deviate from the optimum phase difference, in the case of a small opening of the bypass valve the torque will decrease, it is true, but remains positive so that the engine still supplies power. When the bypass valve is further opened, the torque will become zero, and when it is still further opened it will even become negative so that the engine can absorb power. in a given position of the bypass valve a maximum negative torque is obtained and upon further opening the negative torque decreases again. When the present hot gas engine is applied for traction purposes, braking with the engine can be effected consequently by means of the bypass valve. The value of the braking torque supplied by the engine depends upon the pressure in the engine and upon the number of revolutions, in addition to the position which the bypass valve assumes. Accordingly, as the pressure is higher, the supplied barking torque will be larger.

ln known hot gas engines of the type to which the present invention relates, a power control device is present with which on the one hand the inlet cock can be opened and on the other hand the exhaust cock can be set to its exhaust position and simultaneously the bypass valve can be opened. Through the exhaust the medium is removed from the working space(s) and upon reaching the desired pressure (required power), both the exhaust and the bypass cock are closed. This means that a high braking torque cannot be supplied by the engine for a longer period of time.

It is the object of the invention to provide a hot gas engine comprising a control device with which the inlet exhaust and bypass cocks can be operated so that for a long period of time, for example, when a vehicle drives down a slope, a high braking torque can be supplied.

In order to achieve the object of this invention, the hot gas engine has a first control device which is movable against the action of a spring for controlling the inlet and exhaust cocks and which, upon movement against the action of the spring, brings the inlet cock in its open position and, uponmovement in the direction of the action of the spring, bringstheexhaust cock in its exhaust position; said movement in the direction of spring action being restricted by a first fixed stop member. The engine furthermore comprises a second control device which is likewise movable against the action of a spring for controlling the bypass valve, which control device, upon movement against the action of the spring, closes the bypass valve or moves it to its closed position and, upon movement in the direction of the action of the spring, opensit or opens it further, the movement of said second control device in the direction of the action of the spring being limited by a second stop member. Each of the two control devices is coupled to a pressure-sensitive element which, dependent upon the pressure in the working space(s) of the engine, assumes a given position in such manner that when the pressure in the working space(s) increases or decreases, the adjustment .of the two control devices varies in that sense that the inlet cock moves to its closed position and the exhaust cock moves to its nonexhaust position, respectively, and the bypass valve moves to its closed position. The first and the second stop members are arranged so that the distance over which the first control device is movable in the direction of the action of the spring, is smaller than the distance over which the second control device is movable in that direction, The engine furthermore comprises an element which is sensitive to the number of revolutions; when the number of revolutions, reduces below a zero load number of revolutions this element may be adjustable. To move the second control device away from the second stop member, the second control device being constructed so that in a position of the two control devices in which the bypass valve is closed and the inlet and exhaust cock both assume their closed and nonexhaust position, respectively, a movement of the second control device also results in an equally large movement of the first control device.

During normal operation of the hot gas engine according to the invention the inlet cock can be opened upon movement against the action of the spring by moving the second control device with which simultaneously the first control device is.

also moved. As result of this medium will flow to the working space(s) of the engine through the medium supply duct. As a result of this the pressure in said working space(s) will increase so that the pressure-sensitive element experiences a displacement in that sense that the ,control devices experience a movement opposite to the initial movement so that the inlet cock is closed. The same, but then in the reverse direction, occurs upon moving the control devices in the direction of the action of the spring, the first control device again following the second. In this manner a given pressure level in the working space(s) is reached that is associated with any position of the control devices. So a given power supplied by the engine is associated with any position of the control devices, so that said control devices are comparable to the accelerator of internal combustion engines. When the two control devices are entirely released, a movement of the first control device takes place until it engages the stop member, the second control device experiencing a slightly larger displacement until it engages the second stop member. The exhaust valve then is in its exhaust position and the bypass valve is maximally opened, that is to say, the engine supplies a maximum braking torque. Medium is now conducted away from the working space(s) through the outlet duct, so that the pressure therein decreases as a result of which the pressure-sensitive element experiences a displacement, thereby also moving the control devices. Due to this movement the exhaust cock moves to its nonexhaust or closed position and the bypass valve moves to its closed position. As a result of the unequal arrangement of the stop members the bypass-closing member will not reach its exhaust position until the exhaust cock is closed. The pressure in the working space(s) does not vary any longer and the pressure-sensitive element becomes stationary. However, the bypass-closing valve is not yet closed. Since in the case of an opened bypass the revolutions against torque curve of the engine is distorted in such manner that no stable point of intersection is to be found with the revolutions against torque curve of the load, the danger exists that in this situation the engine stops. In order to prevent this, an element which is sensitive to the number of revolutions is present, which, when the number of revolutions falls below an adjusted zero-load number of revolutions, moves the second control device away from the second stop member and hence in the first instance closes the bypass valve.

When a traction vehicle in which engine is disposed drives down a slope, the number of revolutions increases, the second control device will engage the second stop member; the bypass cock being opened. When the supplied braking torque is too low, the inlet cock can be opened by moving the first control device alone as result of which the pressure level in the engine increases and the braking torque also increases. In this manner it is possible to supply a large braking torque for a long period of time so that the working power of the vehicle can be fully absorbed by the engine.

In a favorable embodiment of the hot gas engine according to the invention, the first control device comprises a first lever one end pivotally secured to the pressure-sensitive element and the other end coupled in one direction of movement to a first operating device and in the other direction of movement connected to a fixed part by means of a spring, which spring, in the case of nonenergized operating device, pulls the first lever against the first stop member. The second control device comprises a second lever having one end pivotally secured to the pressure-sensitive element and the other end coupled in one direction of movement to a second operating device and in the other direction of movement connected to a fixed part by means of a spring, which spring in the case of nonenergized operating device, pulls the second lever against the second stop member. The first and the second stop members are arranged so that upon displacement in the direction of the action of the spring the first lever contacts the first stop member sooner than the second lever contacts the second stop member; the second lever and/or the second operating device are arranged or provided with catches so that upon displacement of the second lever against the action of the spring the first lever is also moved. In this manner an extremely simple construction for controlling the position of the relative cocks is obtained, in which during normal operation both control devices can simultaneously be displaced by means of the second operating device, while upon braking with the engine the first control device can be moved alone with the first operating device until the desired pressure level in the working space(s) has adjusted; while in that case the second lever remains engaging the second stop member due to the action of the spring thereby keeping the bypass cock maximally opened so that a maximum braking torque is supplied.

A further favorable embodiment of the hot gas engine according to the invention includes the first control device which comprises a first movable liquid column having one end bounded by a piston cooperating with the inlet and exhaust cock and forced against the liquid column by the action of a spring, and the other end bounded by a first movable piston; the second control device comprises a second movable liquid column having one end is bounded by a piston which cooperates with the bypass valve and is forced against the liquid column by the action of a spring and the other end bounded by a second movable piston. A first operating device is present with which the first movable piston can be moved, as well as a second operating device being present with which simultaneously the first and the second movable piston can be moved; the first and second stop members are furthermore arranged so that the movement of the first movable piston in the direction of the action of the spring is smaller than that of the second movable piston, each of the two liquid columns being furthermore bounded by a further piston which is connected to the pressure-sensitive element.

In order that the invention may be readily carried into effect, it will now be described in greater detail, by way of example, with reference to the accompanying drawings, in which FIG. 1 diagrammatically shows not to scale a monocylinder hot gas engine having a control device;

FIG. 2 diagrammatically shows a part of the control device of the hot gas engine shown in FIG. 1, in which an exhaust cock is provided in a communication between the suction and compression duct of the compressor;

FIG. 3 diagrammatically shows not to scale a four-cylinder hot gas engine having a control device;

FIG. 4 shows another embodiment of the control device shown in FIG. 2.

Reference numeral 1 in FIG. 1 denotes a cylinder in which a piston 2 and a displacer 3 reciprocate. The piston 2 and the displacer 3 are connected by a piston rod 4 and a displacer rod 5, respectively, to a gear not shown. Between the piston 2 and the displacer 3 there is a compression space 6 which communicates with an expansion space 10 via a cooler 7, a regenerator 8 and a heater 9. Thermal energy can be applied to the heater 9 by a burner 11. Below the piston 2 there is a buffer space 12 which communicates, through a capillary duct 13, with the compression space 6 so that in the buffer space 12 always the same average pressure will adjust as in the compression space 6.

A medium supply duct 15 in which a nonreturn or one-way valve 16 is provided which permits flow of medium in the direction of the working space communicates with the compression space 6. The medium supply duct 15 furthermore comprises a controllable suppletion cock or inlet valve 17. With its side remote from the compression space the medium supply duct 15 communicates with a storage container 18 containing working medium.

A medium outlet duct 20 communicates with the compression space 6 and comprises a nonreturn or one-way valve 21 which prevents flow of medium in the direction of the compression space and furthermore comprises a controllable exhaust cock or valve 22. With its side remote from the compression space the medium outlet duct 20 communicates with the inlet 23 of a compressor 24. The outlet 25 of the compressor 24 communicates with the storage container 18 through a duct 26.

A communication duct 27v communicates with the compression space 6 and comprises a controllable bypass cock or valve 28 which opens into the buffer space 12 at its other end.

Two control devices of which the first comprises a lever 30 and the second comprises a lever 31 are present for operating the exhaust and

inlet valves

22 and 17 and the bypass valve 28. Both levers are pivotally secured at their one end at 32 and 33 to a pressure-sensitive element 34 consisting of a piston 34 in a cylinder 35. The space 36 of one side of the piston 34 communicates through a duct 37 with the buffer space 12 so that in said bufi'er space the same average pressure will prevail as in the working space 6. A spring 38 is operative on the other side of the piston 34.

The first lever 30 is coupled at one end through a transmission 39 to an operating member 40 and at its other end it is coupled to a fixed part of the engine through a tension spring 41. A stop member 42 restricts the movement of the lever 30 in the direction of the action of the spring at its positive position. The second lever 31 is connected at its one end through a transmission 43 to an operating member 44, and is connected to a fixed part at its other end by a tension spring 45, the movement of the lever 31 in the direction of the action of the spring being limited by a stop member 46 at its positive position. The transmission 43 comprises a catch 47 which is arranged so that when the lever 31 is parallel to the lever 30 the two levers are simultaneously movable by means of the operating device 44.

The operation of the hot gas engine is assumed to be known. The control thereof occurs as follows. Starting or neutral position is the position shown of the control device in which the inlet cock 17, the exhaust cock 22 and the bypass cock 28 are all closed. When the coupling 43 is moved to the right to negative position by means of the operating member 44, the two

levers

30 and 31 also move to the right and hence reach the negative positions shown in broken lines I and II In this position of the levers the bypass cock 28 and the exhaust cock 22 remain closed while the suppletion cock 17 is opened. Medium from the storage container 18 will now flow to the working space of the hot gas engine through the supply duct 15. As a result of this the average pressure in the working space and in the buffer space 12 and hence also in the space 36 of the pressure-sensitive element increases. This has for its result that the piston 34 is moved to the left or positive position against the action of the spring 38. The

pivots

32 and 33 of the levers also move to the left so that the inlet cock 17 moves to its closed position, At the instant the

levers

30 and 31 have reached their neutral positions I and II" shown in dot and dash lines, the inlet cock 17 is again closed so that the neutral position of the control device is then reached again in which a higher average pressure prevails in the working space and the engine will supply a larger torque. When the operating member 44 is released, the

levers

30 and 31 move to the left or positive position while opening both the exhaust cock 22 and the bypass cock 28. By opening the exhaust cock 22, medium from the working space is drawn off via outlet duct 22 to the compressor 24 and is then pumped back to the storage container 18. As a result of this the average pressure in the working space of the engine and hence the supplied power decrease. Furthermore, the bypass cock 28 is opened and due to flow losses occurring in said cock the phase between the volume and pressure variations in the compression and expansion space varies so that a large power reduction occurs. When the operating member 44 is entirely released the

levers

30 and 31 are pulled to positive position against the

stop members

42 and 46 by

springs

41 and 45, respectively. The stop member 42 is arranged so that the lever 30 engages it sooner than lever 31 engages stop member 46. The catch 47 is then released from the lever 30. In this positive position of the

levers

30 and 31 which is denoted by the broken lines 111' and IV, the exhaust cock 22 and the bypass cock 28 are opened, Medium is conducted away from the working space via the exhaust cock 22 and the compressor 24 so that the pressure drops. The result of this is that the pressure in the space 36 also drops as the piston 34 moves to the right under the influence of the spring 38. As a result of this the ends 32 and 33 of the

levers

30 and 31 also move to the right. When the neutral position III of the lever 30, dot and dash lines has been reached, the exhaust cock 22 is closed again. The lever 31 now takes a position IV" in which, however, the bypass cock 28 is not yet closed. A large braking torque is supplied by the maximally opened bypass cock which might have for its result that the engine cuts out. In order to prevent this a revolutions control 50 is present which, when the number of revolutions becomes smaller than the zero-load number of revolutions, moves the lever 31 away from the stop member 45 so that the bypass aperture becomes so much smaller that the zero-load number of revolutions remains maintained. I

When the number of revolutions of the engine increases, for example, because the vehicle in which the engine is arranged as a traction engine drives down a hill, braking with the engine is possible by energizing the operating pedal 40. With this operating pedal only lever 30 is moved to the right to negative position. This has for its result that the suppletion cock 17 is opened and medium flows to the working space. As a result of this the pressure rises. As a result of this rise in pressure the piston 34 moves to the left as a result of which the ends 32 and 33 of the

levers

30 and 31 also move to the left. As a result of this the inlet cock 17 closes and the bypass cock 28 is further opened. The bypass cock 28 is constructed so that in the case of maximum pressure in the working space the aperture of the bypass cock 28 is such that the engine supplies a maximum braking torque.

In this manner it is thus possible to adapt during normal operation the torque supplied by the engine to the required torque by means of one operating device 44, while the engine can supply a braking torque by means of a second operating device 40 so that working power of movement can .be converted via the engine into thermal energy which can be conducted away with the cooling water in the cooler 7.

In FIG. 2 the exhaust cock 22 is directly provided in the medium outlet duct 20. Without altering the control device the outlet of medium can also be controlled by an exhaust cock 22 which is arranged in a communication 'duct 51 between the medium outlet duct 20 and the duct 26. The only difference is that in the open condition of the exhaust cock 22' no removal of medium out of the working space takes place but that removal takes place only when the exhaust cock 22' is closed, The operation of the control is entirely similar to that shown in FIG. 1 so that further description thereof may be omitted.

FIG. 3 shows a hot gas engine having four

cylinders

55, 56, 57 and 58. Each of these cylinders communicates, through

nonreturn valves

59, 60, 61 and 62 which permit flow of medium in the direction of the relative cylinder, with a medium supply duct 63. Each of these cylinders communicates further via

nonreturn valves

64, 65, 66 and 67 which prevent flow of medium towards these cylinders, with a medium outlet duct 68. The medium supply duct 63 comprises a controllable inlet cock 17 and communicates at its other end with a storage container 18. The medium outlet duct 68 communicates with its other end with the inlet 23 of a compressor 24, the outlet 25 of which communicates with the storage container 18 via a duct 26 with a nonreturn valve 70 incorporated therein. Between the medium outlet duct 68 and the duct 26 a communication duct 50 is present in which an exhaust cock 22 is provided.

The bypass cock 28 is arranged in the communication duct 71 between the medium outlet duct 68 and medium supply duct 63.

The control device corresponds to that shown in F IG. 1 with the difference that in this embodiment the

levers

30 and 31 pivot about the same pivot 72 which is again connected to the piston 34 of a pressure-sensitive element. The space 36 on one side of the piston 34 communicates with the medium outlet duct 68. Since the medium outlet duct 68 communicates with the cylinders via

nonreturn valves

64, 65, 66 and 67 which permit flow in the direction of the duct 68, the maximum pressure which occurs in the working spaces will prevail in the outlet duct 68.

By energizing the operating member 44, both

levers

30 and 31 will move to the left, the inlet cock 17 being opened. Although the exhaust cock 22' is also opened, this has for its result that the suction and compression side of the compressor 24 are inopen communication with each other so that the compressor causes no transport of medium and hence no removal of working medium takes place to the storage contamer.

Medium flows to the working

spaces

55, 56, 57 and 58 through the open inlet cock 17, As a result of this the pressure level in said working spaces and hence also the maximum pressure increases. The pressure in the medium outlet duct 68 and in the space 36 will consequently also increase. As a result of this the piston 34 and consequently also the

levers

30 and 31 move to the right so that the inlet cock 17 moves to its closed position.

When the operating member 44 is released, the

levers

30 and 31 move to the right so that the exhaust cock 22 closes and the bypass cock 28 opens. As a result of the closure of the cock 22, the medium sucked by' the compressor 24 will be conducted away to the storage container 18 so that removal of working medium from the working spaces takes place and the pressure level therein drops. This has for its result that the pressure in the space 36 also drops and the piston 34 moves to the left so that the

levers

30 and 31 also experience a movement to the left and the cock 22' opens again and the cock 28 closes. When the cock 28 is opened, a flow of medium takes place from the outlet duct 68 to the supply duct 63 and then via the working spaces again to the outlet duct 68. Due to this circulation of medium a reduction occurs of the power supplied by the engine.

When the operating device 44 is entirely released, the

levers

30 and 31 are pulled against their

stop members

42 and 46 by the

springs

41 and 45, the lever 30 again contacting the stop member 42 sooner than the lever 31 contacts the stop member 45. This again has for its result as in FIG. 1 that the exhaust cock 22' will again reach its nonexhaust position (closed position) before the bypass cock 28 is opened. In order to prevent the engine from cutting out, in this situation, a revolution control 50 is present again as in FIG. 1; when the number of revolutions passes below the zero-load number of revolutions the control 50 moves the lever away from the stop member 46 so that the bypass aperture is then reduced.

Referring again to FIG. 1, in order to cause the engine to supply a large barking torque, the operating member 40 may be energized again as a result of which the lever 30 alone moves to the right and the inlet cock 17 opens. As a result of this the pressure level in the engine rises. The piston 34 moves to the right as a result of the increased pressure and the bypass cock 28 reaches its maximally open position so that a maximum braking torque is supplied. So in this manner a hot gas engine is obtained having a mountain brake.

Although the control device in the hot gas engines shown in the above figures is constructed with levers, it will be obvious that other constructions are also possible. In FIG. 4 the control device used in the engine shown in FIG. 3 is constructed with movable

liquid columns

130 and 131 instead of movable levers. On one side the liquid column 130 is bounded by a piston 133 which is forced against the liquid by a spring 134 and the piston rod 135 which cooperates with the exhaust cock 22 and suppletion cock 17. The liquid column 131 is bounded on its one side by a piston 136 which is forced against the liquid by a spring 137 and the piston rod 138 of which is connected to a bypass cock 28. At its other end the liquid column 130 is bounded by a piston 140 having a piston rod 141 which comprises

studs

142 and 143, while the liquid column 131 is bounded on its other side by a piston 144 having a piston rod 145 which comprises

studs

146 and 147.

Furthermore a first operating device 148 is present which cooperates with stud 142 while a second operating device 149 cooperates with stud 143 which is connected to the piston 140 and with stud 146 which is connected to piston 144. Further more an element 150 which is sensitive to the number of revolutions is present which when the number of revolutions fall below the zero-load number of revolutions, can cooperate with stud 147 which is connected to the piston 144. Stop

members

151 and 152 limit the movement of the

pistons

140 and 144 in the direction of the action of the

springs

134 and 137, respectively. The

liquid columns

130 and 131 are furthermore bounded by

pistons

153 and 154 the

piston rods

155 and 156 of which are each connected to a piston 34 of a pressure-sensitive element as described in the preceding figures.

By energizing the operating device 14% the

pistons

140 and 144 are both moved downwards. The result of this is that the

pistons

133 and 136 also move downwards. The exhaust cock 22' remains in its nonexhaust position (open) and the inlet cock 17 remains open while the bypass member 28 closes the communication duct 171. Due to the suppletion of working medium the pressure level in the working space increases and also the pressure in the spaces 36 increases so that the pistons 34 move against the action of the spring 38. As a result of this the

pistons

153 and 154 move outwards so that as it were a shortening of the

liquid columns

130 and 131 occurs so that the

pistons

133 and 136 return to their initial position, closing the inlet cock 17.

When the operating device 149 is entirely released the pistons 140133 and 144-136 move upwards until the

piston rods

141 and 145 engage the

stop members

151 and 152. The exhaust cock 22' is then closed so that removal of working medium from the working spaces takes place and bypass member 28 is then maximally open. By the removal of medium the pressure in the working spaces drops and hence also in the spaces 36 so that the pistons 34 move inwards under the influence of the springs 38 thereby, as it were, causing an elongation of the liquid column so that the

pistons

133 and 136 move downwards. This is continued until the exhaust cock 22' is opened again. The bypass member 28 will not yet assume its closed position. If in this situation the number of revolutions falls below the zero-load number. of revolutions, the element 150 which is sensitive to the number of revolutions will contact stud 47 and force said stud downwards so that the bypass member 28 will consequently be closed further.

In order to obtain a large braking torque, the operating member 148 is energized so that the piston 140 alone is moved downwards and the inlet cock 17 is opened so that suppletion of medium takes place and the pressure level increases. As a result of this the pressure in the spaces 36 will also increase so that the

pistons

153 and 154 move outwards as a result of which as it were again a shortening of the liquid columns and 131 occurs and the

pistons

133 and 136 move upwards, thereby again closing the inlet cock 17 and further opening the bypass member 28. The engine then supplies a maximum braking torque.

What is claimed is:

1. In a hot gas engine operable witha source of fluid medium, and including at least one working space, one buffer space, an inlet duct for flowing medium from the source to the working space, and an outlet duct for discharging medium from the working space, the improvement of a control device in combination therewith comprising:

a. a one-way valve in each of said inlet and outlet ducts,

b. an adjustable inlet valve in the inlet duct, and an adjustable exhaust valve in the outlet duct, both valves spring biased in closed position,

. a capillary duct for communicating between and maintaining the same average pressure in the working and buffer spaces,

d. a communication duct including an adjustable bypass valve spring biased in closed position connecting the working space with the buffer space,

first spring-biased control means movable between (i) neutral position whereby the inlet and exhaust valves are closed, (ii) positive position whereby the inlet valve is open and the exhaust valve is closed, and (iii) negative position whereby the exhaust valve is open and the inlet valve is closed,

second spring-biased control means movable between (1) neutral position whereby the bypass valve is closed, and (ii) positive position whereby the bypass valve is open,

g. Third means which engages the first and second means, is in communication with the working space, and is movable between positive, neutral and negative positions in response to increased and reduced pressure respectively in the working space, movement of the third means toward positive and negative positions respectively urging the first and second means toward their corresponding positive and negative positions,

h. a fourth means, engaged to the second means and responsive to engine output speed below zero-load, for moving the second means to effect closure of the bypass valve, and

i. fifth means connecting the first and second means whereby movement of the second means between its positions causes corresponding movement of the first means.

2. Apparatus according to claim 1 comprising stop means for insuring, when the second means is moved to its positive position, it reaches said position before the first means reaches its positive position.

3. Apparatus according to claim 2 wherein the stop means comprises first and second stop elements for arresting motion of the first and second means when they are moved to their positive positions.

4. Apparatus according to claim 1 wherein the fourth means is a centrifugal governor device.

5. Apparatus according to claim 1 wherein the first and second means are levers movable about their respective pivot points, and said third means engages and moves said pivot points to displace the levers to locations corresponding to different positions.

6. Apparatus according to claim 1 wherein said first and second control means are mechanical linkages, each having one part manually operable and a separate part engaged to the associated valve.

7. Apparatus according to claim 1 wherein said first and second control means are fluid linkages comprising containers of movable fluid, each container including one piston engaging the fluid for initiating action thereof, and a second remote piston driven by the fluid for actuating the associated valve.

8. Apparatus according to claim 1 in combination with a plurality of similar hot gas engine working spaces.

9. In a hot gas engine operable with a source of fluid medium, and including one working space, one buffer space, a bypass duct and valve connecting the working and buffer spaces, an inlet duct for flowing medium from the source to the working space, and an outlet duct for discharging medium from the working space, the improvement comprising of a control device in combination therewith,

a. first means for increasing power output of the engine from a neutral condition by providing additional medium to the working space and thereby operating at a higher pressure, and for decreasing power by removing medium to operate at a lower pressure,

b. second means for providing braking torque from the engine, by short circuiting the working and buffer spaces formed by openable bypass duct means therebetween,

c. third means for sensing low engine speed and increasing power to prevent engine stalling by closing said second means duct, and

fourth means for sensing pressure change in the working space and subsequently returning the first and second means to a neutral condition.

10. Apparatus according to claim 9 wherein said first means comprises an inlet valve for permitting medium flow from the source to the working space, and an exhaust valve for permitting discharge of medium from the working space, and a linkage for selectively opening and closing said inlet and outlet valves.

11. Apparatus according to claim 10 wherein said second means comprises a linkage for selectively opening and closing said bypass duct.

Claims

1. In a hot gas engine operable with a source of fluid medium, and including at least one working space, one buffer space, an inlet duct for flowing medium from the source to the working space, and an outlet duct for discharging medium from the working space, the improvement of a control device in combination therewith comprising: a. a one-way valve in each of said inlet and outlet ducts, b. an adjustable inlet valve in the inlet duct, and an adjustable exhaust valve in the outlet duct, both valves spring biased in closed position, c. a capillary duct for communicating between and maintaining the same average pressure in the working and buffer spaces, d. a communication duct including an adjustable bypass valve spring biased in closed position connecting the working space with the buffer space, e. first spring-biased control means movable between (i) neutral position whereby the inlet and exhaust valves are closed, (ii) positive position whereby the inlet valve is open and the exhaust valve is closed, and (iii) negative position whereby the exhaust valve is open and the inlet valve is closed, f. second spring-biased control means movable between (1) neutral position whereby the bypass valve is closed, and (ii) positive position whereby the bypass valve is open, g. Third means which engages the first and second means, is in communication with the working space, and is movable between positive, neutral and negative positions in response to increased and reduced pressure respectively in the working space, movement of the third means toward positive and negative positions respectively urging the first and second means toward their corresponding positive and negative positions, h. a fourth means, engaged to the second means and responsive to engine output speed below zero-load, for moving the second means to effect closure of the bypass valve, and i. fifth means connecting the first and second means whereby movement of the second means between its positions causes corresponding movement of the first means.

9. In a hot gas engine operable with a source of fluid medium, and including one working space, one buffer space, a bypass duct and valve connecting the working and buffer spaces, an inlet duct for flowing medium from the source to the working space, and an outlet duct for discharging medium from the working space, the improvement comprising of a control device in combination therewith, a. first means for increasing power output of the engine from a neutral condition by providing additional medium to the working space and thereby operating at a higher pressure, and for decreasing power by removing medium to operate at a lower pressure, b. second means for providing braking torque from the engine, by short circuiting the working and buffer spaces formed by openable bypass duct means therebetween, c. third means for sensing low engine speed and increasing power to prevent engine stalling by closing said second means duct, and fourth means for sensing pressure change in the working space and subsequently returning the first and second means to a neutral condition.