Stirling engine

Abstract

To avoid damage of a thermosiphon serving as a heat exchanger even when at least one of a pressure and a temperature of a heating medium increases by suppressing the increase without releasing the heating medium to the outside.SOLUTION: A Stirling engine includes: a thermosiphon that accommodates a heating medium receiving heat from a heat source; and an engine part having a body that accommodates work gas. A heater that applies heat to the work gas by using the heating medium is disposed in the body. The Stirling engine also includes an engine control device that executes control for increasing an absorption amount of thermal energy from the heating medium when at least one of a pressure and a temperature of the heating medium exceeds a predetermined value.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a Stirling engine. [Background technology]

[0002] For example, Patent Document 1 discloses a device in which a heat exchanger is provided in a duct through which exhaust air passes, which converts water into steam using heat in the exhaust air, and the steam is guided to a heated object, which is then heated by the heat of condensation. The above heat exchanger, which uses water as a medium (heat medium) for heat exchange, is also called a thermosiphon. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-101299 A Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, when the pressure inside the heat exchanger (pressure of the heat medium) exceeds a certain level, a valve is opened to prevent the pressure from increasing and to achieve efficient heat transfer. However, when the valve is opened, the amount of heat medium filled inside the heat exchanger decreases. This causes the temperature of the heat exchanger exposed to the exhaust heat to rise, which may damage the heat exchanger. Note that such problems can also occur when the valve is opened when the temperature of the heat medium exceeds a certain level.

[0005] The present invention has been made to solve the above problems, and its object is to provide a Stirling engine that can suppress the increase in at least one of the pressure and temperature of the heat transfer medium without releasing the heat transfer medium to the outside, even if the pressure and / or temperature of the heat transfer medium increases, thereby avoiding damage to the thermosiphon, which is a heat exchanger. [Means for solving the problem]

[0006] A Stirling engine according to one aspect of the present invention comprises a thermosiphon that contains a heat medium that receives heat from a heat source, and an engine section having a main body that contains a working gas, in which a heater is disposed within the main body that imparts heat to the working gas by means of the heat medium, and further comprises an engine control device that executes control to increase the amount of thermal energy absorbed from the heat medium when at least one of the pressure and temperature of the heat medium exceeds a predetermined value. Effect of the Invention

[0007] According to the above configuration, even if at least one of the pressure and temperature of the heat medium increases, the increase can be suppressed without releasing the heat medium to the outside, thereby preventing damage to the thermosiphon. [Brief description of the drawings]

[0008] [Figure 1] 1 is an explanatory diagram showing a schematic configuration of a Stirling engine according to an embodiment of the present invention; [Diagram 2] FIG. 2 is an explanatory diagram showing changes in pressure and volume in an expansion space within the main body of the Stirling engine. [Diagram 3] FIG. 4 is an explanatory diagram showing changes in pressure and volume in a compression space in the main body. [Figure 4] FIG. 2 is a block diagram showing a configuration of a main part of the Stirling engine. [Diagram 5] FIG. 2 is an explanatory diagram showing an example of the positions of a pressure detector, a heat medium temperature detector, and a heat source temperature detector provided in the Stirling engine. [Figure 6] FIG. 2 is an explanatory diagram showing an example of an arrangement position of a refrigerant adjustment unit provided in the Stirling engine. [Figure 7] FIG. 2 is a perspective view showing a schematic positional relationship between a flow path of a heat source and a thermosiphon. [Figure 8] FIG. 4 is an explanatory diagram illustrating an example of a positional relationship between a plurality of the heat source temperature detectors and the thermosiphon. [Figure 9] FIG. 11 is an explanatory diagram illustrating another example of the positional relationship. [Figure 10] FIG. 11 is an explanatory diagram showing a schematic diagram of still another example of the positional relationship. [Figure 11] FIG. 13 is a block diagram showing a configuration of a main part of a modified Stirling engine. [Figure 12] FIG. 1 is an explanatory diagram showing a schematic configuration of a Stirling engine according to a first modified example. [Figure 13] FIG. 11 is an explanatory diagram showing a schematic configuration of a Stirling engine according to a second modified example. [Figure 14] FIG. 13 is a perspective view showing a typical thermoelectric element applicable to Modifications 1 and 2. [Figure 15] FIG. 11 is an explanatory diagram showing a schematic configuration of a Stirling engine according to a third modified example. [Figure 16] FIG. 13 is an explanatory diagram showing a schematic configuration of a Stirling engine according to a fourth modified example. [Figure 17] FIG. 13 is an explanatory diagram showing a schematic configuration of a Stirling engine according to a fifth modified example. [Figure 18] FIG. 13 is an explanatory diagram showing a schematic configuration of a Stirling engine according to a sixth modified example. [Figure 19] 13 is a flowchart showing the flow of operations in a Stirling engine of the sixth modified example. [Figure 20] FIG. 13 is an explanatory diagram showing a schematic configuration of a Stirling engine according to a seventh modified example. [Figure 21] 13 is a flowchart showing the flow of operations in a Stirling engine of the seventh modification. [Figure 22] FIG. 13 is a block diagram showing the configuration of a main part of a Stirling engine according to an eighth modified example. [Figure 23] 13 is a flowchart showing the flow of operations in a Stirling engine of Modification 8. [Figure 24] FIG. 11 is an explanatory diagram showing a schematic diagram of changes in each parameter over time. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings.

[0010] <1. Basic structure of Stirling engine> 1 is an explanatory diagram showing a basic configuration of a Stirling engine 100 according to an embodiment of the present invention. The Stirling engine 100 includes a thermosiphon 1 and an engine unit 20.

[0011] (1-1. Thermosyphon) Thermosiphon 1 contains a heat medium that receives heat from a heat source HS. The heat source HS can be, for example, factory waste heat. The heat source HS may also be solar heat or geothermal heat. The heat source HS moves through a flow path FP. The flow path FP is, for example, composed of a heat exhaust pipe.

[0012] Thermosiphon 1 has a first pipe 1a, a second pipe 1b, and a third pipe 1c as pipes through which a heat medium flows. First pipe 1a is located inside flow path FP. Second pipe 1b and third pipe 1c are located outside flow path FP. Thus, a portion of thermosiphon 1 is disposed in flow path FP.

[0013] The second pipe 1b is located downstream of the first pipe 1a in the direction in which the heat medium flows. The first pipe 1a and the second pipe 1b are connected via a first connection part 11. The first connection part 11 is provided on a wall surface of the flow path FP. The end of the second pipe 1b opposite to the end connected to the first pipe 1a is connected to an upper part of the main body 30 of the engine part 20.

[0014] The third pipe 1c is located upstream of the first pipe 1a in the direction in which the heat medium flows. The first pipe 1a and the third pipe 1c are connected via a second connection part 12. The second connection part 12 is provided on the wall surface of the flow path FP. The end of the third pipe 1c opposite to the end connected to the first pipe 1a is connected to the lower part of the main body 30.

[0015] The heat transfer medium contained in the thermosiphon 1 is, for example, water. Water is liquid at room temperature, but at high temperatures it boils and turns into gaseous steam. Steam also condenses into water (condensed water). Therefore, steam and condensed water are also included in the heat transfer medium. The heat transfer medium, in either a liquid or gaseous state, flows through the piping of the thermosiphon 1 and circulates between the heat source HS (flow path FP) and the engine section 20.

[0016] More specifically, when the heat medium (here, water) in the first pipe 1a is heated by the heat source HS (for example, exhaust heat), the water evaporates and becomes steam. The steam passes from the first pipe 1a through the second pipe 1b and is introduced from above into the main body 30 of the engine section 20. The steam releases condensation heat to a heater 40 (described later) in the main body 30, thereby heating the heater 40. After releasing the condensation heat, the steam condenses and becomes water (condensed water). The water is discharged from the bottom of the main body 30 and passes through the third pipe 1c, and is returned to the first pipe 1a. In other words, the condensed water enters the flow path FP of the heat source HS. The above process is repeated thereafter. The heat medium contained in the thermosiphon 1 may be a liquid other than water (for example, alcohol).

[0017] In this way, the thermosiphon 1 receives heat from the heat source HS and exchanges heat with the heater 40. Such a thermosiphon 1 is also called a primary heat exchanger.

[0018] (1-2. Engine Configuration) The engine section 20 has a main body 30. The main body 30 is a cylinder that contains a working gas G. The working gas G is, for example, helium. Since helium has a large specific heat capacity, engine output per volume can be increased by increasing the density by applying high pressure to the helium. The working gas G may be a gas other than helium (for example, air, hydrogen, etc.). Within the main body 30, a heater 40, a cooler 50, and a regenerator 60 are arranged linearly in the horizontal direction.

[0019] The heater 40 is formed of, for example, a shell-and-tube type heat exchanger. The heater 40 is also referred to as a secondary heat exchanger in comparison with the thermosiphon 1 which is a primary heat exchanger. The heater 40 has a heater tube 41 through which the working gas G flows. The heater tube 41 is, for example, a metal tube. The metal constituting the heater tube 41 may be appropriately selected from metals with excellent thermal conductivity, such as aluminum, copper alloy, and stainless steel. In this embodiment, a plurality of heater tubes 41 are provided, but it is sufficient that at least one heater tube 41 is provided.

[0020] Steam introduced from thermosiphon 1 into main body 30 flows around each heater tube 41. This heats each heater tube 41, and the working gas G flowing inside each heater tube 41 is heated. In other words, heater 40 imparts heat transferred by the heat medium of thermosiphon 1 to working gas G.

[0021] One end of the heater 40 communicates with the expansion space ES, and the other end communicates with one end of the regenerator 60. That is, the heater 40 is located between the expansion space ES and the regenerator 60 within the main body 30. The expansion space ES is a space in which the working gas G expands when it is heated by the heater 40.

[0022] The cooler 50 is also configured with a shell-and-tube type heat exchanger similar to the heater 40. That is, the cooler 50 has a plurality of cooling pipes 51 through which the working gas G flows. The cooling pipes 51 are metal pipes similar to the heater pipe 41. In this embodiment, a plurality of cooling pipes 51 are provided, but it is sufficient that at least one cooling pipe is provided.

[0023] When a refrigerant is supplied to the cooler 50 from the cooling equipment 70 installed outside the main body 30 via the refrigerant piping 71, the refrigerant flows around each cooling tube 51. This cools each cooling tube 51, and the working gas G flowing through each cooling tube 51 is cooled. In other words, the cooler 50 cools the working gas G with the refrigerant. The above refrigerant is, for example, water, but a refrigerant other than water may also be used. The refrigerant flows through the refrigerant piping 71 and circulates between the cooler 50 and the cooling equipment 70.

[0024] One end of the cooler 50 communicates with the compression space CS, and the other end of the cooler 50 communicates with the other end of the regenerator 60. That is, the cooler 50 is located between the regenerator 60 and the compression space CS within the main body 30. The compression space CS is a space where the working gas G is compressed by a compression piston CP described later.

[0025] The regenerator 60 is disposed between the heater 40 and the cooler 50. The regenerator 60 is formed, for example, of a mesh-shaped flow path. This allows the working gas G in the main body 30 to circulate between the expansion space ES side and the compression space CS side via the regenerator 60. In other words, the regenerator 60 allows the working gas G to circulate between the expansion space ES and the compression space CS. Note that the regenerator 60 is not limited to a mesh-shaped flow path. For example, the regenerator 60 can also be formed of a heat storage material such as a laminated wire mesh, a thin plate aligned with the flow, or a porous body.

[0026] An expansion piston EP serving as a power piston PP is disposed in the main body 30 on the opposite side of the expansion space ES to the heater 40. Also, a compression piston CP serving as a power piston PP is disposed in the main body 30 on the opposite side of the compression space CS to the cooler 50. That is, in the main body 30, the expansion piston EP is disposed via the heater 40 and the expansion space ES of the working gas G, and the compression piston CP is disposed via the cooler 50 and the compression space CS of the working gas G. Thus, a two-piston type Stirling engine 100 having two pistons (expansion piston EP, compression piston CP) serving as a power piston PP is also called an α-type Stirling engine.

[0027] Piston rings PR are fitted around the outer periphery of the expansion piston EP and the compression piston CP. The piston rings PR act as a gas seal. In other words, the piston rings PR prevent leakage of the working gas G from the gap between the expansion piston EP and the main body 30 and the gap between the compression piston CP and the main body 30 (gas leakage).

[0028] An expansion-side piston rod 81 of the expansion piston EP is connected to an expansion-side crosshead piston 82. The expansion-side crosshead piston 82 is connected to an expansion-side crankshaft 84 via an expansion-side connecting rod 83. The expansion-side piston rod 81 is provided penetrating one end face 30a of the main body 30. Therefore, the expansion-side crosshead piston 82, the expansion-side connecting rod 83, and the expansion-side crankshaft 84 are located outside the main body 30.

[0029] The expansion-side crosshead piston 82, the expansion-side connecting rod 83, and the expansion-side crankshaft 84 constitute an expansion-piston-side crank mechanism 85. The expansion piston EP is connected to the expansion-piston-side crank mechanism 85 via the expansion-side piston rod 81. On one end surface 30a of the main body 30, an expansion-side gas seal portion 31a is provided around a through hole through which the expansion-side piston rod 81 passes.

[0030] A compression-side piston rod 86 of the compression piston CP is connected to a compression-side crosshead piston 87. The compression-side crosshead piston 87 is connected to a compression-side crankshaft 89 via a compression-side connecting rod 88. The compression-side piston rod 86 is provided penetrating the other end face 30b of the main body 30. Therefore, the compression-side crosshead piston 87, the compression-side connecting rod 88, and the compression-side crankshaft 89 are located outside the main body 30.

[0031] The compression side crosshead piston 87, the compression side connecting rod 88, and the compression side crankshaft 89 constitute a compression piston side crank mechanism 90. The compression piston CP is connected to the compression piston side crank mechanism 90 via a compression side piston rod 86. On the other end surface 30b of the main body 30, a compression side gas seal portion 31b is provided around a through hole through which the compression side piston rod 86 passes.

[0032] The expansion piston side crank mechanism 85 and the compression piston side crank mechanism 90 are connected to each other so as to be capable of transmitting power through a power transmission unit 91. More specifically, the expansion side crankshaft 84 of the expansion piston side crank mechanism 85 is connected to the output shaft SH through a first belt 92 so as to be capable of transmitting power. Furthermore, the compression side crankshaft 89 of the compression piston side crank mechanism 90 is connected to the output shaft SH through a second belt 93 so as to be capable of transmitting power. In other words, the first belt 92, the output shaft SH, and the second belt 93 constitute the above-mentioned power transmission unit 91. Note that the power transmission unit 91 may be configured to have a chain, gears, etc., other than or in addition to the belt.

[0033] The output shaft SH is, for example, a rotating shaft of a work machine M. The work machine M is composed of, for example, a generator and a motor. For example, the work machine M operates as a motor only at start-up, and operates as a generator after independent operation.

[0034] (1-3. Engine operation) In the above configuration, when steam flowing through the first pipe 1a and the second pipe 1b of the thermosiphon 1 is introduced into the main body 30 of the engine section 20, the heat of condensation of the steam is imparted to the heater 40, heating the heater 40. The heating of the heater 40 heats the working gas G in the heater tube 41. As a result, the working gas G expands, increasing the pressure in the expansion space ES and pressing against the expansion piston EP. Here, the pressure in the expansion space ES is defined as P E (Pa), and the volume of the expansion space ES is V E (m 3 ), the work load in the expansion process is W E (J) is W E =∫P E dV E It is expressed as:

[0035] As the expansion piston EP is pressed and moved, the expansion-side piston rod 81 and the expansion-side crosshead piston 82 rotate the expansion-side crankshaft 84 in the positive direction via the expansion-side connecting rod 83. The rotation of the expansion-side crankshaft 84 rotates the first belt 92, causing the output shaft SH to rotate in the positive direction. When the output shaft SH rotates, the second belt 93 rotates, causing the compression-side crankshaft 89 to rotate in the positive direction.

[0036] By the rotation of the compression side crankshaft 89, the compression side connecting rod 88 presses the compression side crosshead piston 87 and the compression side piston rod 86, and pushes the compression piston CP into the main body 30. As a result, the compression space CS is compressed, and the working gas G in the compression space CS flows into the cooler 50, and the working gas G is cooled by the cooler 50. Here, the pressure in the compression space CS is expressed as P C (Pa), and the volume of the compression space CS is V C (m 3 ), the work load in the compression process is W C (J) is W C =-∫P C dV C It is expressed as:

[0037] Therefore, when the amount of work required to rotate the output shaft SH (for example, the amount of work required to generate electricity) is W (J), the amount of work W is the amount of work W during the expansion process. E and the work load in the compression process W C and a predetermined mechanical efficiency η of the engine unit 20, the following equation is used: W = (W E +W C ) η=(∫P E dV E -∫P C dV C )·η

[0038] The expansion and compression steps are repeated by the reciprocating movements of the expansion piston EP and the compression piston CP. At this time, the pressure P E and volume V E In the compression space CS, the pressure PC and volume V C This changes as shown in FIG.

[0039] (1-4. Timing) As described above, the power imparted to the expansion piston side crank mechanism 85 by the movement of the expansion piston EP shown in FIG. 1 is transmitted to the compression piston side crank mechanism 90 via the first belt 92, the output shaft SH, and the second belt 93.

[0040] Here, the expansion piston EP and the compression piston CP reciprocate within the main body 30 with a predetermined phase difference. The phase difference corresponds to the difference between the crank angle of the expansion piston-side crank mechanism 85 and the crank angle of the compression piston-side crank mechanism 90. Therefore, for example, when the rotation angle (crank angle) of the expansion-side crankshaft 84 from a reference position is θ (°), the rotation angle (crank angle) of the compression-side crankshaft 89 from a reference position is expressed as (θ-β), where β (°) is a phase lag. The phase lag β is, for example, 90°, but is not limited to 90°.

[0041] The expansion piston side crank mechanism 85 and the compression piston side crank mechanism 90 are pre-timed to realize the above-mentioned phase difference. Such timing can be achieved, for example, by connecting the expansion side crankshaft 84 to the output shaft SH via a first belt 92 at a predetermined rotational position, and connecting the compression side crankshaft 89 to the output shaft SH via a second belt 93 at a predetermined rotational position.

[0042] Specifically, the expansion side crankshaft 84 and the first belt 92 are provided with marks for alignment. The compression side crankshaft 89 and the second belt 93 are provided with marks for alignment. Therefore, by aligning the marks of the expansion side crankshaft 84 and the first belt 92 and connecting them, and aligning the marks of the compression side crankshaft 89 and the second belt 93 and connecting them, the expansion side crankshaft 84 can be connected to the output shaft SH via the first belt 92 at a predetermined rotational position, and the compression side crankshaft 89 can be connected to the output shaft SH via the second belt 93 at a predetermined rotational position. The first belt 92 and the second belt 93 used at this time are preferably toothed belts, i.e., timing belts. In this manner, timing is performed. That is, the expansion piston side crank mechanism 85 and the compression piston side crank mechanism 90 are connected to each other via the power transmission unit 91 so as to be capable of timing.

[0043] In this embodiment, the expansion piston side crank mechanism 85 and the compression piston side crank mechanism 90 are connected via a power transmission unit 91 so as to be capable of transmitting power and adjusting timing, but it is sufficient that they are connected so as to enable at least one of power transmission and timing.

[0044] <2. Main components of the Stirling engine> Fig. 4 is a block diagram showing the configuration of the main parts of the Stirling engine 100. The Stirling engine 100 of this embodiment further includes a pressure detector 21, a heat medium temperature detector 22, a heat source temperature detector 23, a refrigerant adjustment unit 24, a rotation speed control unit 25, a memory unit 26, and an inverter 27. Fig. 5 shows an example of the arrangement positions of the pressure detector 21, the heat medium temperature detector 22, and the heat source temperature detector 23. Fig. 6 shows an example of the arrangement position of the refrigerant adjustment unit 24.

[0045] Pressure detector 21 is a pressure sensor that detects the pressure of the heat medium in thermosiphon 1. As shown in Fig. 5, for example, pressure detector 21 is attached to third pipe 1c in thermosiphon 1, through which condensed water discharged from main body 30 flows toward flow path FP of heat source HS.

[0046] Heat medium temperature detector 22 is a temperature sensor that detects the temperature of the heat medium in thermosiphon 1. Heat medium temperature detector 22 is attached, for example, to second pipe 1b in thermosiphon 1, through which the heat medium flows from flow path FP of heat source HS toward main body 30.

[0047] The heat source temperature detector 23 is a temperature sensor that detects the temperature of the heat source HS. The heat source temperature detector 23 is disposed in the flow path FP of the heat source HS. In this embodiment, a plurality of heat source temperature detectors 23 are provided, but one may be provided. The location of the heat source temperature detector 23 will be described in detail later.

[0048] The refrigerant adjustment unit 24 adjusts at least one of the amount of water and the temperature of the refrigerant. For example, the refrigerant adjustment unit 24 includes at least one of a valve that adjusts the amount of water in the refrigerant and a cooler that adjusts the temperature of the refrigerant. As shown in Fig. 6, the refrigerant adjustment unit 24 is installed in a refrigerant supply pipe 71a through which the refrigerant flows from the cooling equipment 70 toward the cooler 50 in the main body 30. The refrigerant supply pipe 71a constitutes a part of the refrigerant piping 71 described above.

[0049] The rotation speed control unit 25 controls the rotation speed of the working machine M driven by the engine unit 20. In particular, when at least one of the pressure and temperature of the heat medium exceeds a predetermined value, the rotation speed control unit 25 increases the rotation speed of the working machine M to a value higher than the rotation speed at the time when the predetermined value was exceeded. Such a rotation speed control unit 25 is configured, for example, with a central processing unit called a CPU (Central Processing Unit). The pressure and temperature of the heat medium can be recognized by the rotation speed control unit 25 based on the detection results of the pressure detector 21 and the heat medium temperature detector 22 described above. In addition, the rotation speed control unit 25 can recognize the rotation speed at the time when the predetermined value is exceeded based on the detection result of the encoder EN described later.

[0050] Here, the rotation speed of the work machine M refers to the rotation speed of the above-mentioned output shaft SH, which is the rotation shaft of the work machine M. The rotation speed control unit 25 is connected to the inverter 27. The inverter 27 controls the AC voltage supplied to the work machine M based on a control signal (rotation speed command value) output from the rotation speed control unit 25, thereby controlling the rotation speed of the output shaft SH of the work machine M. Therefore, the rotation speed control unit 25 can control the rotation speed of the work machine M by controlling the inverter 27. It is to be noted that the rotation speed control unit 25 and the inverter 27 may be provided integrally with the work machine M.

[0051] The work machine M also includes an encoder EN. The encoder EN is a rotation speed detection unit that detects the rotation speed of a rotating shaft (output shaft SH) of the work machine M. Information on the detected rotation speed is fed back from the encoder EN to the rotation speed control unit 25. As a result, the rotation speed control unit 25 can change (for example, increase) the rotation speed of the work machine M from the current rotation speed based on the information fed back from the encoder EN.

[0052] The storage unit 26 is a memory that stores various information, and is composed of a RAM (Random Access Memory), a ROM (Read Only Memory), a hard disk, an optical disk, a non-volatile memory, etc. The storage unit 26 temporarily stores detection values ​​detected by various sensors such as the pressure detector 21 described above. In addition, various predetermined values ​​described later are also stored in the storage unit 26.

[0053] <3. Specific examples of rotation speed control> The following describes a specific example of rotation speed control by the rotation speed control unit 25. The above-described rotation speed control unit 25 can control the rotation speed of the work machine M by any of the following controls.

[0054] (3-1. First control) When the pressure of the heat transfer medium detected by the pressure detector 21 exceeds a first predetermined value as the above-mentioned predetermined value, the rotation speed control unit 25 increases the rotation speed of the work machine M (more than the rotation speed at the time when the above-mentioned pressure exceeded the first predetermined value).

[0055] When the rotation speed of the engine section 20 is forcibly increased, the engine section 20 absorbs more heat transferred from the thermosiphon 1 via the heat medium. In other words, heat exchange between the heater 40 and the working gas G is promoted, which also promotes heat exchange via the heat medium between the thermosiphon 1 and the engine section 20 (particularly the heater 40). Therefore, when the pressure of the heat medium inside the thermosiphon 1 rises above a first predetermined value, the increase in pressure of the heat medium is suppressed by increasing the rotation speed of the work machine M. When the pressure of the heat medium falls below the first predetermined value, the control of increasing the rotation speed is terminated.

[0056] (3-2. Second control) When the temperature of the heat medium detected by the heat medium temperature detector 22 exceeds a second predetermined value as the above-mentioned predetermined value, the rotation speed control unit 25 increases the rotation speed of the work machine M (more than the rotation speed at the time when the above-mentioned temperature exceeded the second predetermined value).

[0057] When the temperature of the heat medium inside the thermosiphon 1 rises above the second predetermined value, increasing the rotation speed of the work machine M suppresses the temperature rise of the heat medium inside the thermosiphon 1 for the same reason as above (promotion of heat exchange). When the temperature of the heat medium falls below the second predetermined value, the control of increasing the rotation speed ends.

[0058] (2-3. Third control) When the temperature of the heat source HS detected by the heat source temperature detector 23 exceeds a third predetermined value corresponding to the above-mentioned predetermined value (e.g., the first predetermined value), the rotation speed control unit 25 increases the rotation speed of the work machine M (more than the rotation speed at the time when the above-mentioned temperature exceeded the third predetermined value).

[0059] When the temperature of the heat source HS exceeds the third predetermined value, it is expected that the temperature of the heat medium inside the thermosiphon 1 that receives heat from the heat source HS will exceed the above-mentioned first predetermined value. When the temperature of the heat source HS rises above the third predetermined value, increasing the rotation speed of the work machine M suppresses the temperature rise of the heat medium inside the thermosiphon 1 that receives heat from the heat source HS for the same reason as above (promotion of heat exchange).

[0060] In the third control, the control of increasing the rotation speed is continued unless the temperature of the heat source HS falls below the third predetermined value. Note that the third control may be combined with at least one of the second control and the first control to directly monitor the temperature or pressure of the heat medium. In this case, even if the temperature of the heat source HS exceeds the third predetermined value, if the temperature of the heat medium falls below the second predetermined value or if the pressure of the heat medium falls below the first predetermined value, the control of increasing the rotation speed can be terminated.

[0061] As described above, in this embodiment, when at least one of the pressure and temperature of the heat medium contained in thermosiphon 1 exceeds a preset predetermined value, the output of engine section 20 is increased to a level higher than the output at the time when the predetermined value was exceeded (first to third controls). Specifically, rotation speed control section 25 increases the rotation speed of working machine M to a level higher than the rotation speed at the time when the predetermined value was exceeded.

[0062] As described above, if at least one of the pressure and temperature of the heat medium (hereinafter also referred to as pressure, etc.) rises and the heat medium is released to the outside of thermosiphon 1, the amount of heat medium filled inside thermosiphon 1 will decrease, and thermosiphon 1 may be damaged. In this embodiment, even if the pressure, etc. of the heat medium rises, the first to third controls make it possible to suppress the increase in the pressure, etc. of the heat medium without allowing the heat medium inside thermosiphon 1 to escape to the outside. As a result, it is possible to avoid damage to thermosiphon 1 that would occur by releasing the heat medium to the outside.

[0063] (3-4. Fourth Control) The rotation speed control unit 25 may increase the rotation speed of the working machine M by controlling at least one of the amount of water and the temperature of the refrigerant cooling the cooler 50 when at least one of the pressure and the temperature of the heat medium exceeds a predetermined value set in advance. Specifically, when at least one of the pressure and the temperature of the heat medium exceeds a predetermined value, the rotation speed control unit 25 increases the amount of water in the refrigerant from a predetermined specified value, or decreases the temperature of the refrigerant from a predetermined set value, thereby increasing the rotation speed of the working machine M to a value higher than the rotation speed at the time when the predetermined value was exceeded. The rotation speed control unit 25 can recognize the pressure and temperature of the heat medium based on the detection values ​​of the pressure detector 21 and the heat medium temperature detector 22, respectively.

[0064] Increasing the amount of water in the refrigerant or decreasing the temperature of the refrigerant reduces the temperature of the working gas G cooled by the refrigerant. This promotes heat exchange between the heat medium and the working gas G in the heater 40. As a result, the rotation speed of the work machine M can be increased. Therefore, in addition to the first to third controls described above, at least one of the amount of water and the temperature of the refrigerant may be controlled to suppress a rise in the temperature of the heat medium, thereby avoiding damage to the thermosiphon 1.

[0065] In particular, in a configuration in which the engine unit 20 includes the refrigerant adjustment unit 24, when at least one of the pressure and temperature of the heat medium exceeds the above-mentioned predetermined value, the rotation speed control unit 25 may control the refrigerant adjustment unit 24 to increase the rotation speed of the work machine M. On the other hand, in a configuration in which the engine unit 20 does not include the refrigerant adjustment unit 24, the rotation speed control unit 25 may directly control the cooling equipment 70 to change the amount or temperature of the refrigerant.

[0066] <4. Placement of heat source temperature detector> Fig. 7 is a perspective view showing a schematic representation of the positional relationship between the flow path FP of the heat source HS and the thermosiphon 1. Fig. 8 is an explanatory diagram showing a schematic representation of an example of the positional relationship between multiple heat source temperature detectors 23 and the thermosiphon 1 when the flow path FP is viewed from the upstream side. Note that Fig. 8 illustrates an example in which there are two heat source temperature detectors 23. Also, in Fig. 8, the plane on which the two heat source temperature detectors 23 are located is indicated by S.

[0067] In the third control described above, it is desirable that the rotation speed control unit 25 determines the temperature of the heat source HS based on a plurality of temperatures detected by a plurality of heat source temperature detectors 23. For example, as shown in Fig. 8, when the number of heat source temperature detectors 23 is two and the detected temperatures of the heat source temperature detectors 23 are T1 (°C) and T2 (°C), the rotation speed control unit 25 can calculate T = (T1 + T2) / 2 to calculate the temperature T of the heat source HS to be compared with the third predetermined value.

[0068] Only one heat source temperature detector 23 may be used, but in this case, the predetermined value (third predetermined value) must be set on the safe side, and it becomes necessary to set the predetermined value low. By providing multiple heat source temperature detectors 23, the average value of the heat source temperature can be calculated and compared with the predetermined value as described above, so that the reliability of the heat source temperature compared with the predetermined value increases, and it becomes unnecessary to set the predetermined value sufficiently low on the safe side. By raising the predetermined value, the upper limit temperature of the heat source HS at which the optimal rotation speed can be maintained increases, and the total amount of work (power generation) increases. Therefore, from this point of view, it is desirable for the rotation speed control unit 25 to determine the temperature T of the heat source HS based on the detected temperatures of the multiple heat source temperature detectors 23.

[0069] In particular, as shown in Figure 8, it is desirable to arrange one of the two heat source temperature detectors 23 at the radial center of the flow path FP and the other at the radial outside within the flow path FP, in order to realize rotation speed control that takes into account the temperature variation and detection error of the heat source HS in the radial direction of the flow path FP.

[0070] 9 and 10 are explanatory diagrams showing schematic diagrams of other examples of the positional relationship between the multiple heat source temperature detectors 23 and the thermosiphon 1 when the flow path FP is viewed from the upstream side. Both of FIGS. 9 and 10 show a case where the number of heat source temperature detectors 23 is five. As shown in FIG. 9, one of the multiple heat source temperature detectors 23 may be disposed at the radial center of the flow path FP, and the remaining detectors may all be disposed at positions in the flow path FP that are the same radial distance from the flow path center. Also, as shown in FIG. 10, one of the multiple heat source temperature detectors 23 may be disposed at the radial center of the flow path FP, and at least one of the remaining detectors may be disposed at a position in the flow path FP that is a different radial distance from the flow path center than the others.

[0071] Incidentally, in the flow path FP through which the heat source HS moves, the temperature of the heat source HS is higher upstream of the thermosiphon 1 than downstream. This is because the temperature of the heat source HS drops downstream of the thermosiphon 1 as the heat of the heat source HS is transferred to the heat medium of the thermosiphon 1. In order to accurately monitor the effect of the heat of the heat source HS on the heat medium, it is desirable to detect the temperature on the higher side of the heat source HS rather than the temperature on the lower side, and to perform the above-mentioned rotation speed control based on the detected temperature. From this perspective, it is desirable to arrange multiple heat source temperature detectors 23 upstream of the flow path FP with respect to the thermosiphon 1, as shown in FIG. 7.

[0072] <5. Supplementary Information> In this embodiment, as shown in FIG. 1, the expansion piston EP and the heater 40 are arranged in a straight line in the movement direction of the expansion piston EP in the main body 30. In addition, the cooler 50 and the compression piston CP are arranged in a straight line in the movement direction of the compression piston CP in the main body 30. The movement direction of the expansion piston EP refers to the direction in which the expansion piston EP reciprocates in the main body 30 due to the expansion of the working gas G in the main body 30 and the rotation of the expansion side crankshaft 84. On the other hand, the movement direction of the compression piston CP refers to the direction in which the compression piston CP reciprocates in the main body 30 due to the compression of the working gas G in the main body 30 and the rotation of the compression side crankshaft 89. In this case, the entire expansion space ES between the expansion piston EP and the heater 40 can be made to contribute to the pressing of the expansion piston EP. In addition, the entire compression space CS between the cooler 50 and the compression piston CP can be made to contribute to the retraction of the compression piston CP. Therefore, there is no void space in the expansion space ES that does not contribute to the pressing of the expansion piston EP. Moreover, in the compression space CS, there is no void space that does not contribute to the drawing in of the compression piston CP. As a result, by heating the working gas G by the heater 40 and cooling the working gas G by the cooler 50, the Stirling engine 100 (particularly the engine section 20) can be driven efficiently, and the output of the engine section 20 (specifically the rotation speed of the output shaft SH) can be increased.

[0073] Therefore, from the viewpoint of reducing the dead space and increasing the output of the engine section 20, it is desirable that the expansion piston EP and the heater 40 are arranged in a straight line within the main body 30, and that the cooler 50 and the compression piston CP are also arranged in a straight line within the main body 30.

[0074] Furthermore, if there is a bend in the flow path inside the main body 30, there is a concern that pressure loss will occur at the bend, which will result in a decrease in the output of the engine section 20. From the perspective of avoiding a decrease in the output of the engine section 20 due to the pressure loss, it is desirable to arrange the expansion piston EP, heater 40, cooler 50, and compression piston CP in a straight line inside the main body 30, as shown in FIG.

[0075] In addition, when it is more important to realize a compact layout than to prevent a reduction in the output of the engine unit 20 due to pressure loss, the main body 30 may have a curved portion. For example, when the regenerator 60 is positioned extending in one direction within the main body 30, the expansion piston EP and the heater 40 may be arranged side by side in a direction intersecting the one direction within the main body 30, and the cooler 50 and the compression piston CP may also be arranged side by side in a direction intersecting the one direction within the main body 30. In other words, the expansion piston EP and the heater 40, and the cooler 50 and the compression piston CP may be arranged side by side in parallel.

[0076] <6. Variations> In the Stirling engine 100 described above, the rotation speed control unit 25 increases the rotation speed of the working machine M to increase the output of the engine unit 20 when at least one of the pressure and temperature of the heat medium exceeds a predetermined value. The increase in the output of the engine unit 20 increases the amount of thermal energy absorbed from the heat medium flowing inside the thermosiphon 1 in the engine unit 20. This makes it possible to suppress an increase in the pressure of the heat medium. Therefore, it can be said that the Stirling engine 100 described above executes control in which the rotation speed control unit 25 increases the amount of thermal energy absorbed from the heat medium when at least one of the pressure and temperature of the heat medium exceeds a predetermined value. At this time, the control to increase the amount of absorption is control to increase the output of the engine unit 20, more specifically, control to increase the rotation speed of the working machine M.

[0077] The control for increasing the amount of thermal energy absorbed from the heat medium when at least one of the pressure and temperature of the heat medium exceeds a predetermined value is not limited to the above-mentioned control for increasing the output of the engine unit 20. Other examples of the control for increasing the amount of thermal energy absorbed will be described below as modified examples.

[0078] FIG. 11 is a block diagram showing the configuration of the main parts of a modified Stirling engine 100. As shown in the figure, the Stirling engine 100 includes an engine control device 20a. When at least one of the pressure and temperature of the heat medium exceeds a predetermined value, the engine control device 20a executes control to increase the amount of thermal energy absorbed from the heat medium (compared to the amount absorbed at the time when the pressure and temperature of the heat medium exceed the predetermined value). The engine control device 20a can determine whether or not at least one of the pressure and temperature of the heat medium exceeds the predetermined value based on the detection results of at least one of the pressure detector 21, the heat medium temperature detector 22, and the heat source temperature detector 23 described above.

[0079] Such an engine control device 20a includes the above-mentioned rotation speed control unit 25 and a valve control unit 28. The valve control unit 28 is a controller that controls the opening and closing (switching) of a control valve V, which will be described later, and is configured, for example, by a CPU, similar to the rotation speed control unit 25.

[0080] The rotation speed control unit 25 alone can constitute the engine control device 20a. For example, the rotation speed control unit 25 shown in FIG. 4 alone constitutes the engine control device 20a. Similarly, the valve control unit 28 alone can constitute the engine control device 20a. Therefore, the engine control device 20a only needs to be configured to include at least one of the rotation speed control unit 25 and the valve control unit 28.

[0081] The control valve V is provided in a path through which a fluid flows. Here, the fluid is a heat medium or a refrigerant. The control valve V switches between allowing and blocking the fluid into the path based on the control of the valve control unit 28. Such a control valve V is, for example, configured as a solenoid valve or an electromagnetic proportional valve. The control valve V includes at least one of a first control valve V1, a second control valve V2, a third control valve V3, a fourth control valve V4, a fifth control valve V5, and a sixth control valve V6. Hereinafter, the configuration and control for increasing the amount of thermal energy absorbed by the heat medium when the pressure of the heat medium exceeds a predetermined value, including the arrangement of each control valve V, will be described.

[0082] (6-1. Variation 1) FIG. 12 is an explanatory diagram showing a schematic configuration of a Stirling engine 100 of the first modification. In the Stirling engine 100 of the first modification, a heat exchanger 200 is arranged in the middle of the heat medium flow path 10 through which the heat medium flows via the heater 40. A cooling liquid flow path 72 is provided through which the cooling liquid for cooling the heat medium flows via the heat exchanger 200, and a first control valve V1 and a second control valve V2 are arranged in the middle of the cooling liquid flow path 72. The rest is the same as the configuration shown in FIG. 1. Note that in FIG. 12, illustration of a part of the configuration shown in FIG. 1 is omitted for convenience. Specifically, illustration of the configuration on the expansion piston side crank mechanism 85 side and the configuration on the compression piston side crank mechanism 90 side with respect to the main body 30 of the engine part 20 is omitted, and the power transmission part 91 is omitted. Such an illustration method is the same in the drawings that will appear later.

[0083] The heat exchanger 200 is composed of a condenser 200a that cools and condenses the heat medium. The heat exchanger 200 has a folded structure in which the piping through which the heat medium flows is folded back multiple times, similar to the first piping 1a. The folded piping structure lengthens the piping, and increases the heat transfer area of ​​the heat medium flowing through the piping. This allows the heat exchanger 200 to efficiently absorb thermal energy from the heat medium.

[0084] The heat medium flow passage 10 includes the first pipe 1a, the second pipe 1b, and the third pipe 1c. In the first modification, the heat exchanger 200 is provided in the middle of the second pipe 1b. That is, the heat exchanger 200 is provided upstream of the heater 40 in the flow direction of the heat medium flowing through the heat medium flow passage 10.

[0085] The cooling liquid flow path 72 is a pipe through which the refrigerant (cooling liquid) flows from the refrigerant outlet 50a of the cooler 50 toward the cooling equipment 70, and is provided separately from the above-mentioned refrigerant piping 71. The cooling liquid flowing through the cooling liquid flow path 72 cools the heat medium in the heat exchanger 200 and returns to the cooling equipment 70. The first control valve V1 is provided in the cooling liquid flow path 72 between the refrigerant outlet 50a and the heat exchanger 200. The second control valve V2 is provided in the cooling liquid flow path 72 between the heat exchanger 200 and the cooling equipment 70. The cooling equipment 70 includes a pump for discharging the refrigerant therein. The pump may be provided outside the cooling equipment 70 (for example, in the refrigerant piping 71 or the cooling liquid flow path 72).

[0086] The heat medium (steam) flowing from the first pipe 1a to the second pipe 1b of the heat medium flow path 10 passes through a heat exchanger 200 provided in the second pipe 1b, and is led to the upper part of the main body 30. In the main body 30, the heat medium releases condensation heat to the heater 40, thereby heating the heater 40. After releasing the condensation heat, the heat medium condenses into water, which is discharged from the lower part of the main body 30, passes through the third pipe 1c, and is returned to the first pipe 1a.

[0087] Here, when at least one of the pressure and temperature of the heat medium in the heat medium flow passage 10 exceeds a predetermined value, the valve control unit 28 electrically controls the first control valve V1 and the second control valve V2 to open the first control valve V1 and the second control valve V2. Then, in the coolant flow passage 72, the coolant discharged from the refrigerant outlet 50a flows toward the heat exchanger 200 via the first control valve V1, and cools the heat medium flowing through the heat exchanger 200. That is, in the heat exchanger 200, the thermal energy of the heat medium is absorbed. In other words, the amount of thermal energy absorbed in the heat exchanger 200 increases compared to the amount absorbed at the time when at least one of the pressure and temperature of the heat medium exceeds a predetermined value (the amount absorbed at this time is zero). The coolant after cooling the heat medium flows through the coolant flow passage 72 via the second control valve V2 and is returned to the cooling equipment 70.

[0088] On the other hand, when the pressure of the heat medium falls below a predetermined value, the valve control unit 28 electrically controls the first control valve V1 and the second control valve V2 to close the first control valve V1 and the second control valve V2. In this case, the refrigerant stops flowing to the heat exchanger 200 through the coolant flow path 72. Therefore, the heat exchanger 200 hardly absorbs thermal energy from the heat medium.

[0089] Thus, in Modification 1, engine control device 20a (particularly valve control section 28) executes control to increase the amount of thermal energy absorbed from the heat medium (in heat exchanger 200) when the pressure, etc., of the heat medium exceeds a predetermined value. By increasing the amount of thermal energy absorbed, it is possible to suppress an increase in the pressure, etc., of the heat medium without increasing engine output and without releasing the heat medium to the outside. This makes it possible to avoid damage to thermosiphon 1 due to an increase in the pressure, etc., of the heat medium.

[0090] In particular, the control for increasing the absorption amount is a cooling control of the heat medium by the heat exchanger 200 provided in the middle of the heat medium flow path 10 through which the heat medium flows via the heater 40. By cooling the heat medium by the heat exchanger 200, that is, by absorbing the surplus energy (thermal energy) of the heat medium by the heat exchanger 200, an increase in the pressure, etc. of the heat medium can be reliably suppressed.

[0091] The cooling liquid for cooling the heat medium in the condenser 200a constituting the heat exchanger 200 is the refrigerant supplied from the refrigerant outlet 50a of the cooler 50. The refrigerant is utilized not only as the cooling water for cooling the cooler 50 but also as the cooling liquid for cooling and condensing the heat medium (steam) in the condenser 200a, so that the refrigerant is utilized effectively.

[0092] (6-2. Variation 2) FIG. 13 is an explanatory diagram showing a schematic configuration of a Stirling engine 100 of Modification 2. The Stirling engine 100 of Modification 2 has the same configuration as Modification 1, except that the position of the heat exchanger 200 (condenser 200a) is changed. Specifically, in the Stirling engine 100 of Modification 2, the heat exchanger 200 is provided midway through the third pipe 1c of the heat medium flow path 10. That is, the heat exchanger 200 is provided downstream of the heater 40 in the flow direction of the heat medium flowing through the heat medium flow path 10. The opening / closing control (switching control) of the first control valve V1 and the second control valve V2 is the same as in Modification 1.

[0093] In a configuration in which the heat exchanger 200 is provided upstream of the heater 40 in the heat transfer medium flow passage 10 as in the first modification, the heat transfer medium that has received heat from the heat source HS is supplied to the heat exchanger 200 in a gaseous (steam) state. Here, when the mass flow rate of the fluid is constant, the flow velocity of steam, which is a gas, when flowing through the piping is greater than that of water, which is a liquid. For this reason, if the piping becomes longer due to the folded-back structure of the piping in the heat exchanger 200, the pressure loss increases, and it becomes difficult for the steam to flow through the piping. As a result, it becomes difficult for the heat transfer medium to be supplied to the heater 40 during normal operation of the engine section 20, and there is a concern that the performance (output) during normal operation will decrease.

[0094] In contrast, in a configuration in which the heat exchanger 200 is provided downstream of the heater 40 in the heat transfer medium flow passage 10 as in the second modification, the heat exchanger 200 is supplied with a liquid heat transfer medium (e.g., water) that has condensed by releasing heat of condensation in the heater 40. When the mass flow rate of the fluid is constant, the flow rate of liquid water is slower when flowing through the piping than that of gaseous steam. Therefore, even if the piping becomes longer due to the folded-back structure of the piping in the heat exchanger 200, the pressure loss does not increase, and the heat transfer medium (water) can easily flow through the piping. Therefore, during normal operation of the engine section 20, the heat transfer medium is easily supplied to the heater 40, making it possible to suppress the deterioration in performance (output) of the engine section 20 that is a concern in the first modification.

[0095] FIG. 14 is a perspective view showing a thermoelectric element 201 that can be applied to the first and second modified examples. The thermoelectric element 201 may be arranged near the piping of the heat exchanger 200 shown in the first and second modified examples, and electric power may be extracted from the thermoelectric element 201. The thermoelectric element 201 is an element that converts thermal energy into electrical energy. For example, one surface 201a of the thermoelectric element 201 is heated by the heat of the heat medium passing through the piping of the heat exchanger 200, and the other surface 201b is cooled. When a temperature difference is applied between the one surface 201a and the other surface 201b in this way, an electromotive force is generated and an electric current flows (Seebeck effect). In this way, by providing the thermoelectric element 201, the surplus energy (thermal energy) of the heat medium can be converted into electrical energy and utilized.

[0096] (6-3. Variation 3) 15 is an explanatory diagram showing a schematic configuration of a Stirling engine 100 of Modification 3. The Stirling engine 100 of Modification 3 has the same configuration as Modification 2, except that a heater bypass path 1d and a third control valve V3 are provided in the heat transfer medium flow path 10.

[0097] The heater bypass path 1d branches off from the second pipe 1b and is connected to the third pipe 1c. As a result, the heater bypass path 1d is provided to bypass the heater 40. The third control valve V3 is a heater bypass path switching valve that switches between flowing in and blocking the heat medium from the second pipe 1b to the heater bypass path 1d. The third control valve V3 is provided midway along the heater bypass path 1d. Here, the third control valve V3 is configured as an electromagnetic valve. In this way, the heat medium flow path 10 includes the heater bypass path 1d that bypasses the heater 40 and the third control valve V3 as a heater bypass path switching valve.

[0098] In the configuration of the modified example 3, when at least one of the pressure and temperature of the heat medium exceeds a predetermined value, the valve control unit 28 (see FIG. 11) of the engine control device 20a electrically controls the third control valve V3 to open the third control valve V3. As a result, the heat medium flowing through the second pipe 1b is not supplied to the heater 40, but flows into the heater bypass path 1d via the third control valve V3 and is supplied to the heat exchanger 200. When the pressure of the heat medium becomes equal to or lower than a predetermined value, the valve control unit 28 electrically controls the third control valve V3 to close the third control valve V3. As a result, the heat medium flowing through the second pipe 1b is supplied to the heater 40 to heat the heater 40.

[0099] In this way, by providing the heater bypass path 1d and the third control valve V3 in the heat medium flow path 10, when overheating occurs such that the pressure of the heat medium exceeds a predetermined value, the heat medium can be caused to flow into the heater bypass path 1d via the third control valve V3 by control of the valve control unit 28. In other words, the amount of heat medium supplied to the heater 40 can be reduced. This suppresses an excessive increase in engine output due to overheating, that is, an overload of the engine unit 20.

[0100] Incidentally, when the third control valve V3 is configured as an electromagnetic valve, the third control valve V3 is controlled to have two values, that is, whether or not the heat medium flows to the heater 40. When the pressure of the heat medium exceeds a predetermined value, the heat medium does not flow to the heater 40, and there is a concern that a decrease in the output of the engine section 20 may occur. From the viewpoint of suppressing such a decrease in the output of the engine section 20, it is preferable to configure the third control valve V3 as an electromagnetic proportional valve. In this case, by electrically controlling the third control valve V3, it is possible to cause a part of the heat medium flowing through the second pipe 1b to flow into the heater bypass path 1d via the third control valve V3, while supplying the remaining heat medium to the heater 40. Therefore, a decrease in the output of the engine section 20 due to a shortage of the heat medium supply to the heater 40 is suppressed.

[0101] The third control valve V3 may be configured as a check valve (relief valve) in addition to a solenoid valve and a proportional solenoid valve. A check valve is a valve that automatically releases pressure when the pressure in the path (piping) exceeds a predetermined value. When the third control valve V3 is configured as a check valve, electrical control of the third control valve V3 by the valve control unit 28 is not required.

[0102] (6-4. Variation 4) 16 is an explanatory diagram showing a schematic configuration of a Stirling engine 100 of Modification 4. The Stirling engine 100 of Modification 4 has the same configuration as Modification 2, except that a heat exchanger bypass passage 1e and a fourth control valve V4 are provided in the heat medium flow passage 10.

[0103] The heat exchanger bypass path 1e is provided in the third pipe 1c, connecting the upstream side and the downstream side of the heat exchanger 200. That is, the heat exchanger bypass path 1e is provided in the third pipe 1c, bypassing the heat exchanger 200. The fourth control valve V4 is a heat exchanger bypass path switching valve that switches between flowing in and blocking the heat medium from the third pipe 1c to the heat exchanger bypass path 1e. The fourth control valve V4 is provided in the middle of the heat exchanger bypass path 1e. Here, the fourth control valve V4 is configured as an electromagnetic valve. In this way, the heat medium flow path 10 includes the heat exchanger bypass path 1e through which the heat medium flowing via the heater 40 flows bypassing the heat exchanger 200, and the fourth control valve V4 as a heat exchanger bypass path switching valve.

[0104] In the configuration of the fourth modification, when at least one of the pressure and temperature of the heat medium exceeds a predetermined value, the valve control unit 28 of the engine control device 20a electrically controls the fourth control valve V4 to close the fourth control valve V4. As a result, the heat medium discharged from the heater 40 and flowing through the third pipe 1c does not flow into the heat exchanger bypass path 1e, but is supplied to the heat exchanger 200. On the other hand, when the pressure of the heat medium becomes equal to or lower than a predetermined value, the valve control unit 28 electrically controls the fourth control valve V4 to open the fourth control valve V4. As a result, the heat medium discharged from the heater 40 and flowing through the third pipe 1c flows into the heat exchanger bypass path 1e and bypasses the heat exchanger 200. In other words, the heat medium is not supplied to the heat exchanger 200.

[0105] In this manner, in the fourth modification, the heat medium flow passage 10 is provided with the heat exchanger bypass passage 1e and the fourth control valve V4. In this configuration, as described above, when the pressure of the heat medium exceeds a predetermined value, the valve control unit 28 controls the fourth control valve V4 to prevent the heat medium from flowing into the heat exchanger bypass passage 1e, thereby allowing the heat medium to flow into the heat exchanger 200. As a result, only when the pressure of the heat medium exceeds a predetermined value and overheating occurs, the heat medium can be caused to flow into the heat exchanger 200 to absorb thermal energy. Furthermore, when overheating does not occur, the heat medium flows bypassing the heat exchanger 200, so that the thermal energy of the heat medium is not wasted by the heat exchanger 200. As a result, the thermal energy of the heat medium can be effectively used to heat the heater 40, and a decrease in output during normal operation of the engine unit 20 can be suppressed. Furthermore, when overheating does not occur, the heat medium flows bypassing the heat exchanger 200, so that no pressure loss of the heat medium occurs in the heat exchanger 200.

[0106] (6-5. Variation 5) 17 is an explanatory diagram showing a schematic configuration of a Stirling engine 100 of Modification 5. The Stirling engine 100 of Modification 5 is further provided with a coolant supply path 73 that joins with the coolant flow path 72, a fifth control valve V5 is provided in the coolant flow path 72, and a sixth control valve V6 is provided in the coolant supply path 73. The rest of the configuration is the same as that of Modification 2.

[0107] The coolant flow path 72 has a supply port 72a. The supply port 72a is connected to, for example, the refrigerant outlet 50a of the cooler 50. Therefore, the refrigerant discharged from the refrigerant outlet 50a flows from the supply port 72a through the first control valve V1 toward the heat exchanger 200 and is used as a coolant that cools the heat medium in the heat exchanger 200. That is, the supply port 72a constitutes a coolant supply port that supplies the coolant that cools the heat medium to the heat exchanger 200. The coolant after cooling the heat medium in the heat exchanger 200 flows in order through the fifth control valve V5 and the second control valve V2 described later and is returned to the cooling equipment 70. In this way, the Stirling engine 100 of the fifth modification has a coolant flow path 72 through which the coolant flows through the heat exchanger 200.

[0108] The fifth control valve V5 is a coolant release valve provided downstream of the heat exchanger 200 in the flow direction of the coolant in the coolant flow passage 72. More specifically, the fifth control valve V5 is provided between the heat exchanger 200 and the second control valve V2 in the coolant flow passage 72. The fifth control valve V5 may be formed of a solenoid valve or a proportional solenoid valve, or may be formed of a check valve similar to the third control valve V3.

[0109] The cooling liquid supply path 73 is a pipe through which the cooling liquid to be supplied to the heat exchanger 200 flows. The cooling liquid supply path 73 has a first connection port 73a at one end and a second connection port 73b at the other end. The second connection port 73b is connected between the first control valve V1 and the heat exchanger 200 in the cooling liquid flow path 72. The first connection port 73a is connected to a refrigerant outlet of the cooling equipment 70. The refrigerant (cooling liquid) discharged from the cooling equipment 70 passes through the inside of the cooling liquid supply path 73 via the first connection port 73a and flows into the cooling liquid flow path 72 via the second connection port 73b. Therefore, in this case, the second connection port 73b constitutes a supply port for the cooling liquid in the cooling liquid flow path 72. The first connection port 73a may be connected to a facility other than the cooling equipment 70 that discharges the cooling liquid.

[0110] In the configuration of the fifth modified example, when the amount of coolant that cools the heat medium flowing through the heat exchanger 200 is insufficient, the coolant evaporates, and the pressure in the coolant flow path 72 increases. When the pressure in the coolant flow path 72 exceeds a predetermined pressure, the fifth control valve V5 is opened to release the pressure in the coolant flow path 72. At this time, if the fifth control valve V5 is configured as, for example, a check valve, the fifth control valve V5 automatically opens when the pressure in the coolant flow path 72 exceeds the predetermined pressure. On the other hand, if the fifth control valve V5 is configured as, for example, a solenoid valve, the pressure in the coolant flow path 72 is detected by a sensor (not shown), and the valve control unit 28 controls to open the fifth control valve V5 based on a detection signal from the sensor.

[0111] In this way, by providing the fifth control valve V5 as a coolant release valve in the coolant flow path 72, if the pressure in the coolant flow path 72 increases abnormally, the fifth control valve V5 can release the pressure, thereby suppressing the abnormal increase.

[0112] In addition, when the coolant in the coolant flow path 72 is sufficient, the sixth control valve V6 may be closed, and when the coolant is insufficient, the valve control unit 28 may control to open the sixth control valve V6. By opening the sixth control valve V6, the coolant is supplied (supplied) from the cooling equipment 70 to the coolant flow path 72 through the coolant supply path 73, and the shortage of the coolant can be compensated for. In addition, the coolant supplied to the coolant flow path 72 through the cooler 50 removes heat from the cooler 50, and therefore the temperature increases. In contrast, the coolant supplied to the coolant flow path 72 through the coolant supply path 73 from the cooling equipment 70 does not pass through the cooler 50, and therefore has a lower temperature than the coolant supplied to the coolant flow path 72 through the cooler 50. Therefore, the cooling efficiency of the heat medium can be increased by supplying a coolant with a low temperature to the heat exchanger 200.

[0113] (6-6. Variation 6) FIG. 18 is an explanatory diagram showing a schematic configuration of a Stirling engine 100 of Modification 6. The Stirling engine 100 of Modification 6 has a configuration that combines Modifications 3 and 5. The cooling control of the heat medium in this configuration will be described below. Note that, here, the control for cooling the heat medium based on the pressure detected by the pressure detector 21 (see FIG. 11) will be described, but the same can be considered when cooling the heat medium based on the temperature detected by the heat medium temperature detector 22 (see FIG. 11). Also, here, it is assumed that the pressure detector 21 is provided in the second pipe 1b (particularly at a position close to the first pipe 1a).

[0114] 19 is a flowchart showing the flow of operations in the Stirling engine 100 of the sixth modified example. First, the valve control unit 28 judges whether or not the pressure Pv (Pa) detected by the pressure detector 21 exceeds a preset value Pv1 (Pa) (S1). If Pv>Pv1 in S1, the valve control unit 28 opens the first control valve V1 and the second control valve V2 (S2). As a result, the cooling liquid discharged from the refrigerant outlet 50a is supplied to the heat exchanger 200 via the cooling liquid flow path 72, and the heat medium is cooled in the heat exchanger 200.

[0115] When the pressure Pv becomes equal to or lower than the predetermined value Pv1 due to cooling of the heat medium (No in S3), the valve control section 28 closes the first control valve V1 and the second control valve V2 (S4) and ends the cooling control of the heat medium.

[0116] On the other hand, if the pressure Pv continues to exceed the predetermined value Pv1 (Yes in S3), the valve control section 28 further opens the third control valve V3 and the sixth control valve V6 (S5). By opening the third control valve V3, the amount of heat medium supplied to the heater 40 is reduced, and overload of the engine section 20 is suppressed. Furthermore, by opening the sixth control valve V6, the amount of coolant supplied to the heat exchanger 200 is increased, and thus cooling of the heat medium in the heat exchanger 200 is further promoted.

[0117] Thereafter, when the pressure Pv becomes equal to or lower than the predetermined value Pv1 (No in S6), the valve control unit 28 closes all of the first control valve V1, the second control valve V2, the third control valve V3, and the sixth control valve V6 that were open (S7), and ends the cooling control of the heat transfer medium.

[0118] On the other hand, if the pressure Pv continues to exceed the predetermined value Pv1 (Yes in S6), the valve control unit 28 determines that the pressure Pv is rising abnormally and, for example, causes a notification unit (not shown) to notify the user of the abnormality. In this case, an emergency shutdown of the Stirling engine 100 is performed (S8). For example, measures may be taken such as stopping the operation of the heating furnace that generates the heat source HS, stopping the drive of the engine unit 20 (rotation of the output shaft SH), and pulling out the thermosiphon 1 from the flow path FP.

[0119] In the configuration of the sixth modification, the first control valve V1 and the second control valve V2 are controlled with priority, and further the third control valve V3 and the sixth control valve V6 are controlled as necessary, thereby cooling the heat transfer medium.

[0120] (6-7. Variation 7) FIG. 20 is an explanatory diagram showing a schematic configuration of a Stirling engine 100 of Modification 7. The Stirling engine 100 of Modification 7 has a configuration that combines Modifications 4 and 5. Cooling control of the heat medium in this configuration will be described below. Note that here, as in Modification 6, the control of cooling the heat medium based on the pressure detected by the pressure detector 21 will be described.

[0121] 21 is a flowchart showing the flow of operations in the Stirling engine 100 of the seventh modification. First, the valve control unit 28 judges whether or not the pressure Pv detected by the pressure detector 21 exceeds a preset value Pv1 (S11). If Pv>Pv1 in S11, the valve control unit 28 opens the first control valve V1 and the second control valve V2 (S12). As a result, the cooling liquid discharged from the refrigerant outlet 50a is supplied to the heat exchanger 200 via the cooling liquid flow path 72, and the heat medium is cooled in the heat exchanger 200.

[0122] The fourth control valve V4 is closed (S13). When the pressure Pv becomes equal to or lower than the predetermined value Pv1 due to cooling of the heat medium (No in S14), the valve control unit 28 closes the first control valve V1 and the second control valve V2 (S15) and opens the fourth control valve V4 (S16), thereby terminating the cooling control of the heat medium.

[0123] On the other hand, if the pressure Pv continues to exceed the predetermined value Pv1 (Yes in S14), the valve control unit 28 further opens the sixth control valve V6 (S17). This increases the amount of coolant supplied to the heat exchanger 200, further accelerating the cooling of the heat medium in the heat exchanger 200.

[0124] Thereafter, when the pressure Pv becomes equal to or lower than the predetermined value Pv1 (No in S18), the valve control unit 28 closes the first control valve V1, the second control valve V2, and the sixth control valve V6 that were open (S19), opens the fourth control valve V4 (S20), and terminates the cooling control of the heat transfer medium.

[0125] On the other hand, if the pressure Pv continues to exceed the predetermined value Pv1 (Yes in S18), the valve control unit 28 determines that the pressure Pv is abnormally increasing, and, for example, causes a notification unit (not shown) to notify the abnormality. In this case, as in the sixth modification, an emergency stop of the Stirling engine 100 is executed (S21).

[0126] In the configuration of the seventh modified example, the first control valve V1, the second control valve V2, and the fourth control valve V4 are controlled with priority, and further the sixth control valve V6 is controlled as necessary, thereby cooling the heat transfer medium.

[0127] (6-8. Variation 8) FIG. 22 is a block diagram showing the configuration of the main parts of the Stirling engine 100 of the eighth modification. As shown in the figure, the Stirling engine 100 of the eighth modification further includes a working gas pressure sensor 301 and a working gas temperature sensor 302 in addition to the configuration of FIG. 11. The working gas pressure sensor 301 is a sensor that detects the pressure of the working gas G in the main body 30. The working gas temperature sensor 302 is a sensor that detects the temperature of the working gas G in the main body 30. On the other hand, the configuration of the control valve V in the eighth modification is the same as that of the second modification. Therefore, the Stirling engine 100 of the eighth modification has a first control valve V1 and a second control valve V2 as the control valve V. The control valve V may further include a third control valve V3, etc.

[0128] The opening / closing control (switching control) of the first control valve V1 and the second control valve V2 can also be utilized when the engine section 20 is started in a warm state. The warm state refers to a state in which, when the engine section 20 is restarted next time after being started and stopped, the engine section 20 (particularly the inside of the main body 30) has been warmed up by the previous start-up, and the pressure and temperature of the working gas G in the main body 30 are high. The control of the eighth modification will be described below.

[0129] 23 is a flowchart showing the flow of operations in the Stirling engine 100 of the modified example 8. First, the valve control section 28 judges whether or not the Stirling engine 100 (particularly the engine section 20) is in a warmed-up state (S31). This judgment can be performed, for example, as follows.

[0130] FIG. 24 is an explanatory diagram showing a schematic diagram of changes in each parameter over time. Each parameter will now be described. The motor torque Tr (Nm) in FIG. 24 indicates the rotational torque of the output shaft SH (see FIG. 1) of the work machine M (see FIG. 22). This motor torque Tr is detected based on the current output from the work machine M (generator). The rotation speed N (rpm) indicates the rotation speed of the output shaft SH of the work machine M, and is detected based on the output of the encoder EN. The working gas pressure P (Pa) indicates the pressure of the working gas G in the main body 30 detected by the working gas pressure sensor 301. Note that the working gas temperature may be used instead of the working gas pressure. The working gas temperature indicates the temperature of the working gas G in the main body 30 detected by the working gas temperature sensor 302.

[0131] The start-up of the engine unit 20 is defined as time t0. At the start-up, the work machine M is driven as a motor to rotate the output shaft SH. As the rotation speed N of the output shaft SH increases, the working gas pressure P in the main body 30 also increases, and the motor torque Tr also increases. At time tg, the engine unit 20 switches to autonomous operation, and the work machine M is driven as a generator. At time t1, when the motor torque Tr reaches a predetermined torque value Tr0 (rated torque), the rotation speed N, working gas pressure P, and motor torque Tr become constant.

[0132] At time t2, when some cause for stopping (e.g., a power outage, a sensor abnormality, etc.) occurs, the rotation speed N, working gas pressure P, and motor torque Tr start to decrease, and at time t3, the engine section 20 and the work machine M are stopped. When the work machine M stops, the rotation speed N and the motor torque Tr each become zero. On the other hand, the working gas pressure P does not decrease to an initial value (e.g., the pressure at time t0) at time t3, and remains in a state (warm-up state) higher than the predetermined pressure Pc.

[0133] In this state, if the engine unit 20 and the work machine M are restarted, for example at time t4, the internal pressure (working gas pressure P) in the main body 30 is high, so the torque required to start the work machine M becomes large. Also, because the internal pressure in the main body 30 is high, the output of the engine unit 20 (the rotation speed N of the work machine M) becomes excessively large immediately after start-up. That is, as shown in Fig. 24, the motor torque Tr increases significantly on the negative side until spontaneous operation begins, and then increases significantly on the positive side after spontaneous operation (see the graph of the motor torque Tr indicated by the solid line).

[0134] Therefore, at time t3 before time t4, the valve control unit 28 judges whether the rotation speed N of the output shaft SH is equal to or lower than a predetermined rotation speed Nc and whether the working gas pressure P is equal to or higher than a predetermined pressure Pc. If N≦Nc and P≧Pc, the valve control unit 28 judges that the engine unit 20 is in a warm state (the warm state judgment flag becomes "1" indicating a warm state), and opens the first control valve V1 and the second control valve V2 (S32). This increases the amount of thermal energy absorbed from the heat medium by the heat exchanger 200, and reduces the heat input to the engine unit 20 (particularly the heater 40) by the heat medium. Therefore, the working gas pressure P in the main body 30 decreases, and the temperature of the working gas G decreases.

[0135] In this state, when the engine unit 20 and the work machine M are restarted at time t4 (the warm-up determination flag becomes "0" upon restart), the rotation speed N of the output shaft SH increases, and the working gas pressure P and motor torque Tr also increase. Because the pressure and temperature of the working gas G inside the main body 30 decrease from time t3 to time t4, an increase in the torque required to start the work machine M is suppressed, even when restarting at time t4. In addition, the output of the engine unit 20 (the rotation speed N of the work machine M) is also suppressed from becoming excessive immediately after start-up (see the dashed line graph of the motor torque Tr in FIG. 24).

[0136] When a predetermined time tp (sec) has elapsed from time t4 (S33) and the motor torque Tr becomes equal to or less than a predetermined value Tr0 (Nm) (S34), the valve control section 28 closes the first control valve V1 and the second control valve V2 (S35) and ends the series of controls. In Fig. 24, the time when the first control valve V1 and the second control valve V2 are closed is indicated as t5.

[0137] As described above, the control valves V (first control valve V1 and second control valve V2) are provided in the coolant flow passage 72, and when the engine section 20 is in a warm state (when N≦Nc and P≧Pc are satisfied), the valve control section 28 opens the control valve V (S31, S32). This reduces the heat input to the engine section 20 by the heat medium, suppresses an increase in starting torque when the engine section 20 is restarted in a warm state, and suppresses excessive engine output immediately after starting.

[0138] It is of course possible to control the opening and closing of each control valve V by further combining the configurations of each of the modifications 1 to 8 described above.

[0139] <7. Notes> The Stirling engine described in this embodiment can also be expressed as follows.

[0140] The Stirling engine in Appendix (1) is a thermosiphon containing a heat transfer medium that receives heat from a heat source; an engine section having a body that contains a working gas; A Stirling engine in which a heater is disposed in the main body to impart heat to the working gas by the heat medium, The engine control device executes control to increase the amount of thermal energy absorbed from the heat medium when at least one of the pressure and temperature of the heat medium exceeds a predetermined value.

[0141] The Stirling engine of appendix (2) is the Stirling engine of appendix (1), The control for increasing the absorption amount is a control for increasing the output of the engine portion (more than the output at the time when the output exceeds the predetermined value).

[0142] The Stirling engine of appendix (3) is the Stirling engine of appendix (2), The engine control device includes a rotation speed control unit that controls a rotation speed of a work machine driven by the engine unit, The rotation speed control unit increases the rotation speed of the work machine (more than the rotation speed at the time when the pressure and / or the temperature of the heat medium exceed the predetermined value) when at least one of the pressure and the temperature of the heat medium exceeds the predetermined value.

[0143] The Stirling engine of appendix (4) is the Stirling engine of appendix (3), Further comprising a pressure detector for detecting the pressure of the heat medium, The rotation speed control unit increases the rotation speed of the work machine when the pressure of the heat medium exceeds a first predetermined value as the predetermined value.

[0144] The Stirling engine of appendix (5) is the Stirling engine of appendix (3) or (4), A heat medium temperature detector is further provided to detect the temperature of the heat medium. The rotation speed control unit increases the rotation speed of the work machine when the temperature of the heat medium exceeds a second predetermined value as the predetermined value.

[0145] The Stirling engine of appendix (6) is the Stirling engine according to any one of appendix (3) to (5), A heat source temperature detector is further provided to detect a temperature of the heat source. The rotation speed control unit increases the rotation speed of the work machine when the temperature of the heat source exceeds a third predetermined value corresponding to the predetermined value.

[0146] The Stirling engine of appendix (7) is the Stirling engine of appendix (6), A plurality of the heat source temperature detectors are provided, The rotation speed control unit determines the temperature of the heat source based on the temperatures detected by the plurality of heat source temperature detectors.

[0147] The Stirling engine of appendix (8) is the Stirling engine according to appendix (6) or (7), a portion of the thermosiphon is disposed in a flow path through which the heat source moves; The heat source temperature detector is disposed upstream of the thermosiphon (relative to the flow path).

[0148] A Stirling engine according to claim (9) is a Stirling engine according to any one of claims (3) to (8), A cooler that cools the working gas by a refrigerant is further disposed in the main body, The rotation speed control unit increases the rotation speed of the work machine by controlling at least one of the amount of water and the temperature of the refrigerant when at least one of the pressure and the temperature of the heat medium exceeds the predetermined value.

[0149] The Stirling engine of claim 10 is the Stirling engine of claim 9, A refrigerant adjustment unit that adjusts at least one of the amount and temperature of the refrigerant is further provided. The rotation speed control unit controls the refrigerant adjustment unit to increase the rotation speed of the work machine.

[0150] A Stirling engine according to claim (11) is a Stirling engine according to any one of claims (3) to (10), The working machine includes a rotation speed detection unit that detects the rotation speed, The rotation speed control unit recognizes the rotation speed at the point in time when the rotation speed exceeds the predetermined value through detection by the rotation speed detection unit, and controls the rotation speed of the work machine.

[0151] The Stirling engine of appendix (12) is the Stirling engine of appendix (1), The control for increasing the absorption amount is a control for cooling the heat medium by a heat exchanger provided midway along a heat medium flow path through which the heat medium flows via the heater.

[0152] The Stirling engine of claim 13 is the Stirling engine of claim 12, The heat exchanger is a condenser that cools and condenses the heat medium, A cooler is provided in the main body to cool the working gas by a refrigerant, The cooling liquid that cools the heat transfer medium in the condenser is the refrigerant supplied from a refrigerant outlet of the cooler.

[0153] A Stirling engine according to claim (14) is a Stirling engine according to claim (12) or (13), The heat exchanger is provided downstream of the heater in a flow direction of the heat medium flowing through the heat medium flow passage.

[0154] A Stirling engine according to claim (15) is a Stirling engine according to any one of claims (12) to (14), The heat transfer medium flow path is a heater bypass path that bypasses the heater; and a heater bypass path switching valve that switches between allowing and blocking the flow of the heat medium into the heater bypass path.

[0155] The Stirling engine of claim 16 is the Stirling engine of claim 15, the engine control device includes a valve control unit that controls the heater bypass path switching valve, The valve control unit causes the heat medium to flow into the heater bypass path via the heater bypass path switching valve when at least one of the pressure and the temperature of the heat medium exceeds a predetermined value.

[0156] A Stirling engine according to claim (17) is a Stirling engine according to any one of claims (12) to (16), The heat transfer medium flow path is a heat exchanger bypass path through which the heat medium flowing through the heater bypasses the heat exchanger; and a heat exchanger bypass path switching valve for switching between flowing and blocking the heat medium into the heat exchanger bypass path.

[0157] The Stirling engine of claim 18 is the Stirling engine of claim 17, the engine control device includes a valve control unit that controls the heat exchanger bypass path switching valve, When at least one of the pressure and temperature of the heat medium exceeds a predetermined value, the valve control unit controls the heat exchanger bypass path switching valve to prevent the heat medium from flowing into the heat exchanger bypass path, thereby allowing the heat medium to flow into the heat exchanger.

[0158] A Stirling engine according to claim 19 is a Stirling engine according to any one of claims 12 to 18, a cooling liquid flow path having a supply port for a cooling liquid for cooling the heat medium, through which the cooling liquid flows via the heat exchanger; a coolant release valve provided downstream of the heat exchanger in the flow direction of the coolant.

[0159] Although the embodiment of the present invention has been described above, the scope of the present invention is not limited to this, and the invention can be expanded or modified without departing from the spirit of the invention. [Industrial Applicability]

[0160] The present invention can be used in a Stirling engine that utilizes heat from a heat source such as exhaust heat and performs heat exchange to drive an engine section. [Explanation of symbols]

[0161] 1 Thermosyphon 1d Heater bypass route 1e Heat exchanger bypass route 10 Heat transfer medium distribution route 20 Engine section 20a Engine control device 21 Pressure detector 22 Heat medium temperature detector 23 Heat source temperature detector 24 Refrigerant adjustment section 25 Engine speed control unit (engine control device) 28 Valve control unit (engine control device) 30 Main unit 40 Heater 50 Cooler 50a Refrigerant outlet 72 Coolant flow path 72a Supply port 73b Second connection port (supply port) 100 Stirling Engine 200 heat exchanger 200a Condenser EN Encoder (rotation speed detection section) FP flow path G Working gas HS heat source M Work equipment V3 3rd control valve (heater bypass route switching valve) V4 4th control valve (heat exchanger bypass route switching valve) V5 Fifth control valve (coolant discharge valve)

Claims

1. a thermosiphon containing a heat transfer medium that receives heat from a heat source; an engine section having a body that contains a working gas; A Stirling engine in which a heater is disposed in the main body to impart heat to the working gas by the heat medium, A Stirling engine comprising an engine control device that executes control to increase an amount of thermal energy absorbed from the heat medium when at least one of a pressure and a temperature of the heat medium exceeds a predetermined value.

2. 2. The Stirling engine according to claim 1, wherein the control for increasing the absorption amount is control for increasing the output of the engine portion.

3. The engine control device includes a rotation speed control unit that controls a rotation speed of a work machine driven by the engine unit, 3. The Stirling engine according to claim 2, wherein the rotation speed control unit increases the rotation speed of the working machine when at least one of the pressure and the temperature of the heat transfer medium exceeds the predetermined value.

4. Further comprising a pressure detector for detecting the pressure of the heat medium, 4. The Stirling engine according to claim 3, wherein the rotation speed control unit increases the rotation speed of the work machine when the pressure of the heat medium exceeds a first predetermined value as the predetermined value.

5. A heat medium temperature detector is further provided to detect the temperature of the heat medium.

4. The Stirling engine according to claim 3, wherein the rotation speed control unit increases the rotation speed of the work machine when the temperature of the heat transfer medium exceeds a second predetermined value as the predetermined value.

6. A heat source temperature detector is further provided to detect a temperature of the heat source.

4. The Stirling engine according to claim 3, wherein the rotation speed control unit increases the rotation speed of the work machine when the temperature of the heat source exceeds a third predetermined value corresponding to the predetermined value.

7. A plurality of the heat source temperature detectors are provided, 7. The Stirling engine according to claim 6, wherein the rotation speed control unit determines a temperature of the heat source based on temperatures detected by the plurality of heat source temperature detectors.

8. a portion of the thermosiphon is disposed in a flow path through which the heat source moves; 7. The Stirling engine according to claim 6, wherein the heat source temperature detector is disposed upstream of the thermosiphon.

9. A cooler that cools the working gas by a refrigerant is further disposed in the main body, 4. The Stirling engine according to claim 3, wherein the rotation speed control unit increases the rotation speed of the work machine by controlling at least one of an amount of water and a temperature of the refrigerant when at least one of a pressure and a temperature of the heat medium exceeds the predetermined value.

10. A refrigerant adjustment unit that adjusts at least one of the amount and temperature of the refrigerant is further provided. The Stirling engine according to claim 9, wherein the rotation speed control unit increases the rotation speed of the work machine by controlling the refrigerant adjustment unit.

11. The working machine includes a rotation speed detection unit that detects the rotation speed, 11. The Stirling engine according to claim 3, wherein the rotation speed control unit recognizes the rotation speed at the time when the rotation speed exceeds the predetermined value by detection by the rotation speed detection unit, and controls the rotation speed of the work machine.

12. 2. The Stirling engine according to claim 1, wherein the control for increasing the absorption amount is a control for cooling the heat medium by a heat exchanger provided midway along a heat medium flow path through which the heat medium flows via the heater.

13. The heat exchanger is a condenser that cools and condenses the heat medium, A cooler is provided in the main body to cool the working gas by a refrigerant, 13. The Stirling engine according to claim 12, wherein the cooling liquid for cooling the heat transfer medium in the condenser is the refrigerant supplied from a refrigerant outlet of the cooler.

14. 13. The Stirling engine according to claim 12, wherein the heat exchanger is provided downstream of the heater in a flow direction of the heat medium flowing through the heat medium flow passage.

15. The heat transfer medium flow path is a heater bypass path that bypasses the heater; 13. The Stirling engine according to claim 12, further comprising: a heater bypass path switching valve that switches between allowing and blocking the flow of the heat medium into the heater bypass path.

16. the engine control device includes a valve control unit that controls the heater bypass path switching valve, 16. The Stirling engine according to claim 15, wherein the valve control unit causes the heat medium to flow into the heater bypass path via the heater bypass path switching valve when at least one of a pressure and a temperature of the heat medium exceeds a predetermined value.

17. The heat transfer medium flow path is a heat exchanger bypass path through which the heat medium flowing through the heater bypasses the heat exchanger; 13. The Stirling engine according to claim 12, further comprising: a heat exchanger bypass path switching valve that switches between allowing and blocking the flow of the heat medium into the heat exchanger bypass path.

18. the engine control device includes a valve control unit that controls the heat exchanger bypass path switching valve, 18. The Stirling engine according to claim 17, wherein the valve control unit controls the heat exchanger bypass path switching valve to prevent the heat medium from flowing into the heat exchanger bypass path when at least one of a pressure and a temperature of the heat medium exceeds a predetermined value, thereby causing the heat medium to flow into the heat exchanger.

19. a cooling liquid flow path having a supply port for a cooling liquid for cooling the heat medium, through which the cooling liquid flows via the heat exchanger; 19. A Stirling engine according to claim 12, further comprising: a coolant discharge valve provided downstream of the heat exchanger in a flow direction of the coolant.

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