JP5388108B2 - Stirling engine - Google Patents

Description

  The present invention relates to a Stirling engine, and more particularly to a Stirling engine that can convert heat energy into electric energy or the like using exhaust heat as a heat source.

  In recent years, a Stirling engine has attracted attention as a device capable of converting heat energy into electric energy or the like using exhaust heat as a heat source in order to recover heat energy discharged from a ceramic furnace, a waste treatment furnace, or the like.

  As is well known, the basic configuration of a Stirling engine is that a power piston is accommodated in a cylinder, and a displacer piston for moving a working fluid such as air is accommodated in the cylinder. It is configured to move while maintaining a gap, and the one in which these power piston and displacer piston are accommodated in one cylinder is called a one-cylinder type. Furthermore, the displacer piston is arranged to slide in close contact with the inner wall surface of the cylinder in order to improve the thermal efficiency when the working fluid in the cylinder moves between the low temperature space and the high temperature space as the displacer piston moves. In addition, a configuration in which a flow path is formed outside the inner wall surface of the cylinder and a regenerator is disposed in the flow path is common. This regenerator is a regenerative heat exchanger formed of a metal mesh etc., and a model of a Stirling engine in which the displacer itself is formed in a piston shape by a metal mesh of the material of the regenerator is also known. It is not something that can be used.

  A displacer piston and a power piston are connected via a crank mechanism, and a mechanical link type (kinematic type) configured to reciprocate on the same axis while maintaining a constant phase difference, and a crank mechanism are required. A free piston type is known, and an example of the latter is disclosed in Patent Document 1 below.

  In Japanese Patent Laid-Open No. 2004-260260, “the free piston Stirling engine in which the displacer piston and the power piston are not mechanically connected is difficult to keep the phase difference between the pistons constant” In addition, the mechanical loss associated with sliding between the power piston and the rod is reduced, and the centering accuracy of the displacer piston and power piston can be maintained at a low cost without using a complicated and highly accurate expensive spring called a flexure spring. The objective is to keep the phase difference between the axial movements of the displacer piston and the power piston optimal under any operating conditions and to maintain high engine efficiency and output. One of the sliding parts and / or the power pin One of the sliding parts of the ton and the sleeve is subjected to surface hardening treatment such as DLC (diamond-like carbon) coating, and the rod movable member integrally coupled to the rod and the movable member and shaft integrally coupled to the power piston It has been proposed to arrange a plurality of coil springs on the circumference between intermediate fixing members positioned in the middle of the direction and fixed to the case.

Japanese Patent Laying-Open No. 2005-063130

  In the above-mentioned Patent Document 1, the area around the displacer piston is not clearly described. However, as can be seen from the drawing, a sleeve is interposed between the inner wall surface of the cylinder and the displacer piston, and a flow path for the working fluid is formed outside the sleeve. A regenerator or the like is interposed in this flow path. That is, the structure on the displacer piston side follows the conventional structure. For this reason, if the “sliding portion is subjected to a surface hardening treatment such as DLC (diamond-like carbon) coating”, not only the power piston but also the displacer piston can be held in a stable state, Not only does the road resistance increase, but the complicated structure itself forming the flow path outside the sleeve causes a decrease in thermal efficiency, an increase in the size of the housing, an increase in weight, and an increase in manufacturing cost.

  As described above, regardless of whether the conventional Stirling engine is a mechanical link type or a free piston type, the flow temperature and the friction loss around the displacer piston are particularly large. In addition, the internal working fluid is required to have a high pressure of about 3.0 Mpa, and it is very difficult to operate at an intermediate temperature of about 500 ° C., which is a general industrial waste heat. Of course, the housing must inevitably be large and robust to withstand high temperatures and high pressures, and it was not realistic to put it into practical use as an exhaust heat recovery device.

  Therefore, the present invention relates to a Stirling engine in which a displacer piston reciprocates in a cylinder while a working fluid in a high temperature space and a low temperature space periodically moves through a regenerator. It is an object to provide a Stirling engine that can be converted into energy or the like.

In order to solve the above problems, a Stirling engine according to the present invention accommodates a displacer piston in a cylinder to form a high temperature space and a low temperature space, and the working fluid in both spaces moves periodically via a regenerator. In the Stirling engine, the displacer piston is reciprocated in the axial direction of the cylinder, and a power piston arranged coaxially with the displacer piston is reciprocated in the axial direction of the cylinder. The displacer piston is moved axially to the power piston so as to maintain a constant annular gap between the inner wall surface of the cylinder and the outer wall surface of the displacer piston over the entire length of the reciprocating movement trajectory of the displacer piston. rotatably supported to become, thereby forming the regenerator cylindrical body An annular recess is formed on the outer wall surface of the displacer piston, and the regenerator is fitted into the annular recess, and the outer wall surface of the regenerator extends over the entire length of the reciprocating movement path of the displacer piston in the cylinder. The displacer piston is supported by the power piston so as to be axially movable so as to maintain a constant clearance in the circumferential direction between the inner wall surface of the cylinder and the reciprocating movement of the displacer piston in the cylinder. An annular flow path having a certain gap is maintained with respect to the working fluid .

  Alternatively, an annular recess is formed in the inner wall surface of the cylinder, the regenerator is fitted into the annular recess, and the inner wall surface of the regenerator is extended over the entire length of the reciprocating movement path of the displacer piston in the cylinder. The displacer piston is supported by the power piston so as to be axially movable so as to maintain a constant clearance in the circumferential direction between the outer wall surface of the displacer piston, and the displacer piston is reciprocated in the cylinder. It is good also as maintaining the annular flow path of the said fixed gap with respect to the said working fluid during a movement. Further, the cylinder is formed by joining a cylinder head and a cylindrical cylinder body, the annular recess is formed in an inner wall surface of the cylinder including a joint portion between the cylinder body and the cylinder head, and the regenerator It is good also as what was fitted in the said annular recessed part so that a junction part may be coat | covered.

  And in the above Stirling engine, the regenerator can be composed of a laminated cylinder having a plurality of metal net layers, and the regenerator has a winding end after winding a single metal net a plurality of times. It is good also as forming the said laminated cylinder body by welding.

  Since this invention is comprised as mentioned above, there exists an effect as described below. That is, according to the Stirling engine configured as described above, a constant annular gap is maintained between the inner wall surface of the cylinder and the outer wall surface of the displacer piston over the entire length of the reciprocating movement path of the displacer piston in the cylinder. In addition, the displacer piston is supported by the power piston so as to be axially movable, a cylindrical regenerator is disposed in the annular gap, and during the reciprocating movement of the displacer piston in the cylinder, an annular flow with a constant gap with respect to the working fluid is provided. Since the regenerator is supported by one of the cylinder and the displacer piston so as to maintain the path, the smooth operation of the displacer piston can be ensured with a simple configuration while suppressing the flow resistance against the working fluid. . Therefore, even when industrial waste heat is used as a heat source, heat energy can be efficiently converted into electric energy or the like. In particular, if the support portion of the power piston that supports the displacer piston so as to be movable in the axial direction is subjected to surface hardening treatment by DLC coating or the like, the displacer piston can be held in a stable state, and the displacer piston in the cylinder can be held. During the reciprocating movement, an annular flow path having a constant gap with respect to the working fluid can be more reliably maintained.

  In the Stirling engine, an annular recess is formed on the outer wall surface of the displacer piston, and a regenerator is fitted into the annular recess, or an annular recess is formed on the inner wall surface of the cylinder, and the regenerator is installed in the annular recess. Even if it fits, it can comprise so that the annular flow path of a fixed gap may be maintained with respect to a working fluid.

  In the above Stirling engine, the regenerator can be constituted by a laminated cylinder having a plurality of metal mesh layers. In particular, after winding a single metal mesh a plurality of times, the winding end is welded and laminated. If a cylindrical body is formed, it can be formed easily and inexpensively.

It is a longitudinal section showing the basic composition of the Stirling engine concerning one embodiment of the present invention. 1 is an enlarged longitudinal sectional view showing a part of the basic configuration of a Stirling engine according to an embodiment of the present invention. It is a perspective view which shows the regenerator with which it uses for one Embodiment of this invention. It is a longitudinal cross-sectional view which expands and shows a part of basic composition of the Stirling engine which concerns on other embodiment of this invention. It is a longitudinal cross-sectional view which shows the specific structure of the Stirling engine which concerns on other embodiment of this invention. It is a longitudinal cross-sectional view which shows the specific structure of the Stirling engine which concerns on other embodiment of this invention. It is a longitudinal cross-sectional view which shows the basic composition of the Stirling engine which concerns on further another embodiment of this invention. It is a circuit diagram which shows an example of a control circuit when applying this invention to a generator and comprising a Stirling engine generator. It is a flowchart which shows the action | operation by the control circuit of FIG.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a basic configuration of a Stirling engine according to an embodiment of the present invention, and FIG. 2 and FIG. FIG. 4 shows a configuration of a characteristic part of a Stirling engine according to another embodiment, and a specific structure thereof is shown in FIGS. Any of the embodiments is a mechanical link type (kinematic type) and generator-integrated Stirling engine, and is used in, for example, a Stirling engine generator SE shown in FIG.

  As shown in FIG. 1, a cylinder 10 of a Stirling engine and a motor generator 2 that functions as an electric motor and a generator are fixed to the housing 1, and both are connected as described later. A displacer piston 20 is accommodated in the cylinder 10 to form a high temperature space HS and a low temperature space LS, and the displacer piston 20 moves in the axial direction of the cylinder 10 while the working fluid in both spaces periodically moves through the regenerator 30. The power piston 40 disposed coaxially with the displacer piston 20 is configured to reciprocate in the axial direction of the cylinder 10. The cylinder 10 is formed by welding a cylinder head 11 and a cylindrical cylinder body 12, and covers the inner wall surface of the cylinder 10 and the outer wall surface of the displacer piston 20 over the entire length of the reciprocating movement locus of the displacer piston 20 in the cylinder 10. The displacer piston 20 is supported by the power piston 40 so as to be movable in the axial direction so as to maintain a constant annular gap CC (clearance d1) therebetween.

  A regenerator 30 formed in a cylindrical shape by a metal mesh is disposed in the annular gap CC, and maintains an annular flow path CP having a constant gap with respect to the working fluid during the reciprocating movement of the displacer piston 20 in the cylinder 10. Thus, the regenerator 30 is supported by the displacer piston 20. The working fluid is a gas, and helium gas is used in this embodiment, but air may be used.

  An annular groove 12g is formed on the outer wall surface of the intermediate portion of the cylinder body 12, and an annular recess 12r is formed. Then, a C-shaped ring member 15 is fitted in the annular groove 12g, and the support cylinder 13 is disposed so as to cover the annular recess 12r. The seal ring is disposed at both axial ends of the annular recess 12r. (Represented by 14 as a representative). A flange portion 13f is integrally formed at an intermediate portion of the support cylinder 13, and when the flange portion 13f is screwed to the housing 1, the support cylinder is connected to the opening step portion 1s of the housing 1 via the seal ring 14. The body 13 is configured to be fixed in a liquid-tight manner. In this case, the ring member 15 abuts against the opening step 1 s of the housing 1 and is held between the housing 1 and the support cylinder 13, so that the cylinder body 12 and the cylinder 10 with respect to the housing 1 are held. The position in the axial direction can be set to a predetermined position (positioning is performed).

  The support cylinder 13 is provided with a cooling medium inflow portion FI and a cooling medium outflow portion FO, and the cooling medium (for example, water) is cooled in the annular space CL defined by the annular recess 12r and the support cylinder 13. It is configured to be introduced from the inflow portion FI and discharged from the cooling medium outflow portion FO, thereby forming a cooler, and a low temperature space LS is formed in the cylinder body 12. On the other hand, the cylinder head 11 is provided with a plurality of heat collecting fins 11f. The cylinder head 11 is heated by a heat source (not shown) through these heat collecting fins 11f, and the high temperature space HS is formed in the cylinder head 11. Is formed. Thus, the displacer piston 20 with the regenerator 30 mounted therein is accommodated in the cylinder 10 so that the regenerator 30 is positioned between the high temperature space HS and the low temperature space LS. Thus, the displacer piston 20 can reciprocate in the axial direction of the cylinder 10 while the working fluid in both spaces periodically moves through the regenerator 30.

  In the embodiment shown in FIG. 1, as shown in an enlarged view in FIG. 2, an annular recess 20 r is formed on the outer wall surface of the displacer piston 20, and a regenerator 30 is fitted into the annular recess 20 r, A constant gap (clearance d2; naturally, d2 <d1) is maintained between the outer wall surface of the regenerator 30 and the inner wall surface of the cylinder 10 over the entire length of the reciprocating trajectory of the displacer piston 20. As described above, the displacer piston 20 is supported by the power piston 40 and is configured to maintain the annular flow path CP having a constant gap (d2) with respect to the working fluid during the reciprocating movement of the displacer piston 20 in the cylinder 10. Has been.

  The regenerator 30 of the present embodiment is composed of a laminated cylinder having a plurality of metal net layers. For example, as shown in FIG. 3 by extracting the regenerator 30, a single metal net is wound a plurality of times. Later, the winding end is spot welded to form a laminated cylinder. Alternatively, the metal net may be wound directly around the outer wall surface of the displacer piston 20 and the end may be fixed by spot welding or the like. Furthermore, it may replace with this and may use the other member which can make the securing of heat storage amount and reduction of ventilation resistance compatible.

  As described above, the displacer piston 20 is supported by the power piston 40 so as to be movable in the axial direction. That is, a rod 50 is fixed to the displacer piston 20, and this rod 50 extends out of the cylinder 10 through the power piston 40 and is supported by the power piston 40 so as to be movable in the axial direction. If the surface hardening process such as the DLC coating described above is performed on the support portion of the rod 50 and / or the power piston 40, the displacer piston 40 can be held in a stable state, and the displacer in the cylinder 10 can be held. During the reciprocating movement of the piston 40, the annular flow path CP having a constant gap with respect to the working fluid can be more reliably maintained. Furthermore, it is preferable to subject the sliding portion between the power piston 40 and the cylinder 10 to a surface hardening treatment by DLC coating or the like.

  Further, one end of a rod 60 is swingably supported by the power piston 40, and a link 72 swingably supported at the tip of the rod 50 with respect to a plate 71 rotatably supported at the other end. The crank mechanism 70 is constituted by these components and is connected to the motor generator 2 via the flywheel 80. The motor generator 2 is constituted by, for example, a known permanent magnet synchronous motor, and functions as an electric motor and a generator. The description of the structure is omitted, but the power generation control is shown in FIGS. Will be described later with reference to FIG.

  As described above, in the cylinder 10 of the present embodiment, neither a sleeve like a conventional Stirling engine nor an annular passage outside thereof is provided. Further, the displacer piston 20 does not have a conventional piston ring or seal. Moreover, the inner wall surface of the cylinder 10 and the outer wall surface of the displacer piston 20 are set so as to always maintain a constant gap (clearance d1). Specifically, since the rod 50 is supported by the power piston 40 so as to be axially movable with a minimum clearance by DLC coating or the like, the annular gap CC is always maintained constant. Instead of the conventional independent passage outside the sleeve, the annular flow path CP functions as a flow path that actively conducts the movement of the working fluid between the high temperature space HS and the low temperature space LS. In this way, only about half of the outer periphery of the regenerator 30 is exposed in the annular gap CC linear in the axial direction, the annular flow path CP is secured, and there is no conventional cooling section, so that the ventilation resistance is minimized. Can be. In addition, it is possible to adjust the minimum fluid resistance by appropriately setting the annular gap CC and the annular flow path CP.

  Next, another embodiment of the present invention will be described with reference to FIGS. In the embodiment shown in FIG. 1, the regenerator 30 is supported by the displacer piston 20 as shown in an enlarged view in FIG. 2, whereas in the other embodiments shown in FIGS. The vessel 30 is supported by the cylinder 10. That is, as shown in an enlarged view of the main portion in FIG. 4, an annular recess 10 r is formed on the inner wall surface of the cylinder 10, and the regenerator 30 is fitted into the annular recess 10 r, so that the displacer piston 20 in the cylinder 10 is fitted. The displacer piston 20 is supported by the power piston 40 so that a constant gap (clearance d2) is maintained in the circumferential direction between the inner wall surface of the regenerator 30 and the outer wall surface of the displacer piston 20 over the entire length of the reciprocating trajectory. During the reciprocating movement of the displacer piston 20 in the cylinder 10, the annular flow path CP having a constant gap (d2) is maintained with respect to the working fluid.

  In particular, an annular recess 10r is formed on the inner wall surface of the cylinder 10 including the joint 10c between the cylinder body 12 and the cylinder head 11, and the regenerator 30 is fitted into the annular recess 10r so as to cover the joint 10c. Has been. Accordingly, the joint portion 10c is not exposed to the movement path of the displacer piston 20, and naturally, the displacer piston 20 does not directly contact the joint portion 10c. 5 and 6 are specific configuration examples of the embodiment shown in FIG. 4 (and FIG. 1), and members substantially the same as those shown in FIGS. 1 to 3 are denoted by the same reference numerals and described. Is omitted. In these drawings, as indicated by a two-dot chain line, a rigid column member disk RP is fixed to the housing 1 by, for example, four rigid member support columns RS, and the disk RP is a heat source pipe or the like (not shown). The housing 1 is supported in a state in which the heat collecting fins 11f of the cylinder head 11 are accommodated therein. For example, in the case of being mounted on the exhaust heat cylinder EX of FIG. 11 described later, the right side and the left side of FIG. 5 and FIG. 5 shows a state in which the high temperature space HS has a minimum capacity and the low temperature space LS has a maximum capacity, and FIG. 6 shows a state in which the high temperature space HS has a maximum capacity and the low temperature space LS has a minimum capacity.

  Since the present embodiment is configured as described above, the smooth operation of the displacer piston can be ensured with a simple configuration while suppressing the flow resistance against the working fluid. Therefore, even when industrial exhaust heat at around 500 ° C. is used as a heat source, heat energy can be efficiently converted into electric energy, so that it can be put to practical use as an exhaust heat recovery device. For example, if the support portion of the power piston 40 that supports the displacer piston 20 so as to be movable in the axial direction is subjected to surface hardening treatment such as DLC coating, the displacer piston 20 can be held in a stable state. The displacer piston 20 can be smoothly reciprocated while the annular flow path CP having a constant gap is reliably maintained even when the working fluid has a pressure of 1 Mpa or less with a medium temperature exhaust heat of about 1C. Moreover, since the piston ring, sleeve, independent passage, etc. in the conventional device are not required, it is possible to increase the efficiency as compared with the conventional device, as well as to reduce the size and weight, and to keep the manufacturing cost low. This improves reliability and durability.

  FIG. 7 shows still another embodiment of the present invention, which constitutes a so-called free piston type Stirling engine. The configuration within the cylinder 10 in the present embodiment is substantially the same as that of the embodiment of FIGS. 4 to 6, and substantially the same members are denoted by the same reference numerals and description thereof is omitted. The housing 1 of the present embodiment is formed by joining two cases 1a and 1b, and a support plate 1c is fixed to a joint portion between both cases. A support member 17 is fixed to the case 1a. The support member 17 has a cylinder portion that forms a cylinder inner wall surface continuously with the inner wall surface of the cylinder 10, and the power piston 40 is slidable in the cylinder portion. Is housed in. A coil 101 and a yoke 102 are fixed around the cylinder portion of the support member 17, and a yoke 103 is fixed to the inner wall surface of the case 1a so as to face them. An annular permanent magnet 104 is interposed between the yokes 102 and 103 to constitute a linear motor generator 100. The linear motor generator 100 generates electric power according to the axial movement of the permanent magnet 104 following the reciprocating motion of the power piston 40, and the coil 101 Output power.

  Since the plate 41 is fixed to the tip of the power piston 40 and the permanent magnet 104 is mounted on the outer periphery of the plate 41, the linear motor generator 100 generates power in accordance with the axial reciprocation of the power piston 40. It will be. On the other hand, the rod 50 fixed to the displacer piston 20 passes through the power piston 40 and extends beyond the support plate 1c, and a plate 51 is fixed to the tip thereof, and the plate 51 and the plate 41 are connected to the support plate 1c. Are arranged in parallel with each other. As shown in FIG. 7, coil springs (typically indicated by SP) are disposed on both sides of the plates 41 and 51, and are supported in a floating state (floating support) with respect to the housing 1, respectively. . Thus, in the present embodiment, the linear motor generator 100 is configured by the coil 101, the yokes 102 and 103, and the permanent magnet 104. The linear motor generator 100 operates as a starter of the electric motor when the Stirling engine is started, and the generator and Functions as a load adjuster.

  As described above, the present invention can be applied to a free piston type, but as a method of taking out work in that case, it is desirable to incorporate a linear motor generator (linear motor and generator). Also, in order to control the relative phase difference between the power piston 40 and the displacer piston 20, a flexure spring is used as before instead of arranging a plurality of coil springs SP as shown in FIG. It is good as well. Furthermore, the linear motor generator may be used for the relative phase difference control between the two pistons, or a relative phase difference control means may be added. Note that the heat source to be acted on is not limited to a high temperature, and it is also possible to use a low-temperature medium such as an LNG gas of about minus 162 ° C., for example.

  Next, FIG. 8 shows an example of a control circuit used for power generation control of the Stirling engine generator SE including the Stirling engine and the motor generator shown in FIG. 1, and the cylinder head 11 constituting the heating side with respect to the Stirling engine. Is mounted so as to extend into the exhaust heat cylinder EX, and the cylinder head 11 is exposed to high-temperature exhaust gas passing through the exhaust heat cylinder EX and heated. The motor generator 2 is connected to a DC power source 202 by a main circuit 201 via a relay RC1 that intermittently connects the motor generator 2, and three circuits are connected in parallel to the main circuit 201. The first circuit is a rotation speed substitute circuit, in which a relatively small resistor 203 and a relatively large resistor 204 are connected in series so that the voltage Vs across the relatively large resistor 204 changes in the range of 0 to 10V. Is set. Since this voltage Vs is proportional to the engine speed, it is used as a value representing the rotational speed. The second circuit is a dummy resistor circuit, and includes a dummy resistor 205 having a capacity capable of absorbing the power generation capacity, and a relay RC2 that intermittently connects the circuit leading to the dummy resistor 205. The third circuit is a battery charging circuit, and a charge controller 206 is interposed between the relay RC3 and the battery 207 for intermittently connecting the third circuit. The voltage of 0 to 30V on the power generation side is regulated to about 14V by the charge controller 206, and supplied to the 12V battery 207 for charging. In addition, power is supplied to the cooling fan 208 attached to the outside via the charge controller 206.

  In FIG. 8, as an example of power use of the battery 207, the DC-AC converter 209 converts the voltage from DC 12 V to AC 100 V and uses the external device 210 such as lighting. It is desirable that the power generated by the external device 210 on the power use side and the Stirling engine generator SE be substantially equal to reduce the power consumed by the dummy resistor 205.

  FIG. 9 is a flowchart for explaining the operation of the control circuit of FIG. 8. When activated in step S1, the relays RC1 and RC3 are turned off (disconnected state) and the relay RC2 is turned on (conducted state). When the cylinder head 11 is heated and it is determined in step S2 that the heat source temperature (temperature in the exhaust heat cylinder EX) Tg has exceeded a reference value Tk (for example, 500 ° C.), the process proceeds to step S3 and the relay RC1 is turned on. Then, the motor generator 2 functions as an electric motor and the Stirling engine is started. Approximately 2 seconds later, when it is determined in step S4 that the aforementioned rotation speed substitute voltage Vs has exceeded the reference voltage Vl, and the independence of the Stirling engine generator SE is confirmed, the process proceeds to step S5 and the relay RC3 is turned on. The battery 207 is charged with the electric power generated by the motor generator 2.

  Since the working fluid of the Stirling engine generator SE is always constant, even if the temperature on the heating side (the temperature in the exhaust heat cylinder EX) varies, the output voltage varies only in the range of 0 to 30V. When fluctuation occurs on the (power generation) load side in accordance with the state of charge of the battery 207, the engine rotation fluctuates greatly because it is input to the Stirling engine at a substantially constant value. For example, when the battery 207 is nearly fully charged and the load on the generator side (motor generator 2 side) becomes low, the voltage Vs becomes relatively high. As a result, if it is determined in step S6 that the voltage Vs has become equal to or higher than the reference voltage Vh, the process proceeds to step S7 before the engine overspeeds, and the relay RC3 is turned off (at this time, the relay RC2 is in step S1). On position), the generated electric power is consumed by the dummy resistor 205. Accordingly, when it is determined in step S6 that the voltage Vs has become less than the reference voltage Vh, the relay RC3 is turned back on in step S8, and the process proceeds to step S9. If it is determined in step S6 that the voltage Vs is lower than the reference voltage Vh, the relay RC3 is maintained in the on state and the process proceeds to step S9.

  On the other hand, when the battery 207 is in a fully discharged state, the load on the generator side increases, so the voltage Vs decreases. As a result, if it is determined in step S9 that the voltage Vs has become equal to or lower than the reference voltage Vl, the process proceeds to step S10, the relay RC2 is turned off, and the circuit of the dummy resistor 205 is cut off. As a result, the engine speed is recovered, and when it is determined in step S9 that voltage Vs has exceeded reference voltage Vl, relay RC2 is turned back on in step S11, and all outputs of motor generator 2 are connected to battery 207. Will be used for charging. Thus, an end determination is made in step S12. If not completed, the process returns to step S6, and the processes in steps S6 to S11 are repeated until it is determined to end.

  As described above, when the battery 207 is in the vicinity of full charge, the load on the generator side becomes light, the engine speed enters an overspeed state, and the voltage Vs becomes equal to or higher than the reference voltage Vh. The charging circuit for the battery 207 is shut off, the power generation side is connected to the dummy resistor 205, the engine rotation is returned to normal, and a part of the power generation is absorbed by the dummy resistor 205. On the other hand, when the power of the battery 207 is consumed and charging is started from a state close to empty discharge, initially, the charging current is large, so the load increases and the engine speed tends to decrease. As a result, when the voltage Vs becomes equal to or lower than the reference voltage Vl, the circuit of the dummy resistor 205 on the generator side is cut off, recovery of the engine speed is promoted, and the voltage on the generator side is Is controlled to be 14V to 30V, and the battery 207 is appropriately charged.

  Thus, the battery 207 can be charged by the Stirling engine generator SE in a stable state without being affected by the change in the temperature condition of the external heat source or the change in the load state due to the intermittent circuit of the dummy resistor 205. it can. If the generated voltage Vs is zero (0) even though the heat source temperature is sufficiently high, this indicates that the Stirling engine is in a stopped state, so that the motor is started quickly and the Stirling engine is always in operation. It is good to control so that it may be maintained.

DESCRIPTION OF SYMBOLS 1 Housing 2 Motor generator 10 Cylinder 11 Cylinder head 12 Cylinder main body 13 Support cylinder 15 Ring member 20 Displacer piston 30 Regenerator 40 Power piston 50, 60 Rod 70 Crank mechanism 80 Flywheel 100 Linear motor generator 101 Coil 104 Permanent magnet HS High temperature Space LS Low temperature space CC Annular gap CP Annular flow path CL Annular space

Claims (5)

A displacer piston is accommodated in the cylinder to form a high temperature space and a low temperature space, and the displacer piston reciprocates in the axial direction of the cylinder while the working fluid in both spaces periodically moves through the regenerator, In a Stirling engine configured such that a power piston arranged coaxially with the displacer piston reciprocates in the axial direction of the cylinder, the cylinder moves over the entire length of the reciprocating trajectory of the displacer piston in the cylinder. The displacer piston is supported by the power piston so as to be axially movable so as to maintain a constant annular gap between the inner wall surface and the outer wall surface of the displacer piston, and the regenerator is formed in a cylindrical body. an annular recess formed on the outer wall surface of said displacer piston with, the The regenerator is fitted in a concave portion, and a constant gap is provided between the outer wall surface of the regenerator and the inner wall surface of the cylinder over the entire length of the reciprocating movement path of the displacer piston in the cylinder. The displacer piston is supported by the power piston so as to be movable in the axial direction so as to maintain a constant pressure, and the annular flow path having the constant gap with respect to the working fluid during the reciprocating movement of the displacer piston in the cylinder. Stirling engine you and maintains the. A displacer piston is accommodated in the cylinder to form a high temperature space and a low temperature space, and the displacer piston reciprocates in the axial direction of the cylinder while the working fluid in both spaces periodically moves through the regenerator, In a Stirling engine configured such that a power piston arranged coaxially with the displacer piston reciprocates in the axial direction of the cylinder, the cylinder moves over the entire length of the reciprocating trajectory of the displacer piston in the cylinder. The displacer piston is supported by the power piston so as to be axially movable so as to maintain a constant annular gap between the inner wall surface and the outer wall surface of the displacer piston, and the regenerator is formed in a cylindrical body. an annular recess formed on the inner wall surface of the cylinder together, wherein the annular recess A living device is fitted, and a constant gap is maintained in the circumferential direction between the inner wall surface of the regenerator and the outer wall surface of the displacer piston over the entire length of the reciprocating movement locus of the displacer piston in the cylinder. As described above, the displacer piston is supported by the power piston so as to be movable in the axial direction, and the annular flow path with the constant gap is maintained with respect to the working fluid during the reciprocating movement of the displacer piston in the cylinder. Stirling engine characterized in that. The cylinder is formed by joining a cylinder head and a cylindrical cylinder body, the annular recess is formed in an inner wall surface of the cylinder including a joint portion between the cylinder body and the cylinder head, and the regenerator is the joint portion. The Stirling engine according to claim 2 , wherein the Stirling engine is fitted into the annular recess so as to cover the engine. The Stirling engine according to any one of claims 1 to 3 , wherein the regenerator is a laminated cylinder having a plurality of metal net layers. 5. The Stirling engine according to claim 4 , wherein the regenerator winds a metal net a plurality of times and welds a winding end portion to form the laminated cylindrical body.

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