JP2005345011A - Sterling engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a Sterling engine provided with a check valve for taking in gas for a gas bearing to a piston and/or a displacer, in which functions of the check valve are not deteriorated by dust. <P>SOLUTION: The piston 12 and the displacer 13 reciprocate with phase difference to each other to move actuation gas between a compression space 45 and an expansion space 46. The check valves 90 are provided on respective end surfaces of the piston 12 and the displacer 13 to take in actuation gas for the gas bearing from the compression space 45. A valve element 93 of the check valve 90 is surrounded by a wall 100 for preventing dust, so that complete closure of the valve element 93 due to dust caught at the valve element 93 can be rarely prevented. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

    The present invention relates to a Stirling engine.

    The Stirling engine is attracting attention as a heat engine that does not cause destruction of the ozone layer because helium, hydrogen, nitrogen or the like is used as a working gas instead of Freon. An example of a Stirling engine can be seen in Patent Document 1.

The Stirling engine often has a mechanism in which the piston and the displacer are supported by being floated from the inner wall of the cylinder by a gas bearing in order to reciprocate the piston and the displacer at high speed. Gas used in the gas bearing is taken into the piston or the displacer from the compression space between the piston and the displacer. A check valve is provided at the intake location so that the taken-in gas does not return to the compression space. The apparatus described in Patent Document 1 has this structure.
JP 2002-349347 A (page 5-8, FIG. 1-15)

    Garbage generated by various causes exists inside the Stirling engine. Garbage is generated, for example, when parts are assembled to each other or when the Stirling engine is operated, and the surface of one or both parts is scraped to become shavings. Garbage floats inside the engine as the working gas flows, but if it adheres to the valve body of the check valve, the function of the check valve is impaired. That is, the valve body is not completely closed, gas leakage occurs, and the internal pressure of the piston and the displacer decreases. This also causes the gas bearing to fail, causing the problem that the piston and / or displacer contacts the cylinder and wears or breaks. Naturally, the performance is reduced due to gas flow loss.

    The present invention has been made in view of the above points, and in a Stirling engine provided with a check valve for taking gas bearing gas into a piston and / or a displacer, the function of the check valve is impaired by dust. The purpose is to avoid.

    In the present invention, the Stirling engine is configured as follows.

    (1) A piston that is reciprocated by a power source and a displacer that reciprocates with a predetermined phase difference with respect to the piston are provided, and the piston and / or displacer is supported in a cylinder by a gas bearing. In the Stirling engine in which the piston and / or the displacer is provided with a check valve for taking in the working gas for the gas bearing, the periphery of the valve body of the check valve is surrounded by a dust control wall.

    (2) In the Stirling engine configured as described above, the check valve is embedded in a through hole formed in the side wall of the piston and / or the displacer, and the inner surface of the through hole is used as a dust control wall.

    (3) In the Stirling engine configured as described above, the check valve protrudes from the inner surface of the piston and / or the displacer, and the inner surface of the piston and / or displacer is used for dust control so as to surround the check valve. Form a wall.

    (4) In the Stirling engine configured as described above, the wall is configured with a cover that is a separate component from the piston and / or the displacer.

    (5) In the Stirling engine configured as described above, a second check valve is provided in the vent hole of the cover.

    (6) In the Stirling engine configured as described above, the opening of the space surrounded by the wall is closed with a dust control filter.

    (1) In the configuration of the present invention, since the periphery of the valve body of the check valve provided in the piston and / or the displacer is surrounded by a dust control wall, the dust is caught on the valve body and prevents the valve body from being completely blocked. The phenomenon is reduced. For this reason, the working gas which has flowed in from the check valve flows to the gas bearing in its entirety without flowing back toward the compression space, and the gas bearing functions completely.

    (2) Since the check valve is embedded in the through-hole formed in the side wall of the piston and / or the displacer and the inner surface of the through-hole is used as a dust control wall, the configuration is simplified.

    (3) Since a check valve is projected on the inner surface of the piston and / or displacer, and a dust control wall is formed on the inner surface of the piston and / or displacer so as to surround the check valve, the piston and / or displacer It is possible to protect the check valve from dust that enters.

    (4) Since the wall is configured with a cover that is a separate component from the piston and / or the displacer, the wall can be easily formed.

    (5) Since the second check valve is provided in the vent hole of the cover, the operation of the check valve can be further ensured.

    (6) Since the opening of the space surrounded by the wall is closed with a dust control filter, the approach of dust to the valve body of the check valve is further prevented, and the check valve does not malfunction.

    The structure of a Stirling engine to which the present invention is to be applied will be described with reference to FIGS. 1 is a cross-sectional view of a Stirling engine, and FIG. 2 is an enlarged view of a main part of FIG.

    The centers of the assembly of the Stirling engine 1 are the cylinders 10 and 11. The axes of the cylinders 10 and 11 are aligned on the same straight line. A piston 12 is inserted into the cylinder 10, and a displacer 13 is inserted into the cylinder 11. During the operation of the Stirling engine 1, the piston 12 and the displacer 13 reciprocate without contacting the inner walls of the cylinders 10 and 11 by a gas bearing described later. The piston 12 and the displacer 13 move with a predetermined phase difference.

    A cup-shaped magnet holder 14 is fixed to one end of the piston 12. A displacer shaft 15 protrudes from one end of the displacer 13. The displacer shaft 15 passes through the piston 12 and the magnet holder 14 so as to freely slide in the axial direction.

    The cylinder 10 holds the linear motor 20 outside the portion corresponding to the operation region of the piston 12. The linear motor 20 includes an outer yoke 22 having a coil 21, an inner yoke 23 provided so as to be in contact with the outer peripheral surface of the cylinder 10, and a ring shape inserted into an annular space between the outer yoke 22 and the inner yoke 23. , A tube 25 surrounding the outer yoke 22, an outer yoke 22, an inner yoke 23, and synthetic resin end brackets 26 and 27 that hold the tube 25 in a predetermined positional relationship. The magnet 24 is fixed to the magnet holder 14.

    The central portion of the spring 30 is fixed to the hub portion of the magnet holder 14. The center portion of the spring 31 is fixed to the displacer shaft 15. The outer peripheral portions of the springs 30 and 31 are fixed to the end bracket 27. A spacer 32 is disposed between the outer peripheries of the springs 30 and 31, whereby the springs 30 and 31 maintain a certain distance. The springs 30 and 31 are disc-shaped materials with spiral cuts and resonate the displacer 13 with a predetermined phase difference (generally about 90 ° phase difference) with respect to the piston 12. Play a role.

    Heat transfer heads 40 and 41 are disposed outside the portion of the cylinder 11 corresponding to the operating region of the displacer 13. The heat transfer head 40 has a ring shape, and the heat transfer head 41 has a cap shape, both of which are made of a metal having good heat conductivity such as copper or copper alloy. The heat transfer heads 40 and 41 are respectively supported outside the cylinder 11 with ring-shaped internal heat exchangers 42 and 43 interposed therebetween. Each of the internal heat exchangers 42 and 43 has air permeability, and transfers the heat of the working gas passing through the inside to the heat transfer heads 40 and 41. The cylinder 10 and the pressure vessel 50 are connected to the heat transfer head 40.

    An annular space surrounded by the heat transfer head 40, the cylinders 10 and 11, the piston 12, the displacer 13, the displacer shaft 15, and the internal heat exchanger 42 becomes a compression space 45. A space surrounded by the heat transfer head 41, the cylinder 11, the displacer 13, and the internal heat exchanger 43 becomes an expansion space 46.

    A regenerator 47 is disposed between the internal heat exchangers 42 and 43. The regenerator 47 is formed by filling a container with a filler (matrix) such as a wire mesh, or winding a thin metal plate or a synthetic resin film in a coil shape, and has a gap through which a working gas passes. A regenerator tube 48 wraps outside the regenerator 47. The regenerator tube 48 forms an airtight passage between the heat transfer heads 40 and 41.

    A cylindrical pressure vessel 50 covers the linear motor 20, the cylinder 10, and the piston 12. The inside of the pressure vessel 50 becomes a bounce space 51.

    The structure of the pressure vessel 50 is as follows. That is, the pressure vessel 50 is divided into two parts, a ring-shaped part 52 joined to the heat transfer head 40 and a dome-shaped part 53 joined to the ring-shaped part 52. The dividing surface is at a right angle to the axis of the Stirling engine 1 and is located across the linear motor 20.

    Both the ring-shaped part 52 and the dome-shaped part 53 are made of stainless steel. One end of the ring-shaped portion 52 is narrowed down in a tapered shape and brazed to the heat transfer head 40. The tapered narrowed portion 52 a is useful for reducing the size of the Stirling engine 1. Flange-shaped portions 54 and 55 are disposed at the other end of the ring-shaped portion 52 and the open end of the dome-shaped portion 53 facing the ring-shaped portion 52.

    The structure of the flange-shaped portions 54 and 55 will be described in detail with reference to FIG. Both the flange-shaped portions 54 and 55 are formed by welding a stainless steel ring formed separately to the ring-shaped portion 52 and the dome-shaped portion 53. The welding is fillet welding 56. In the inner circumferential direction of the flange-shaped portions 54 and 55, a seal member arrangement portion 57 is provided that has a concave flange-shaped portion 54 side and a convex flange-shaped portion 55 side. Sealing can be maintained by disposing the ring-shaped seal member 70 in the seal member disposition portion 57.

    The surface opposite to the joint surface of the flange-shaped portions 54 and 55 is formed in a shape having a concave step so that the brazing material does not flow out from the contact surface when the fillet weld 56 is applied.

    Annular grooves 74 are formed on the inner peripheral surfaces of the flange-shaped portions 54 and 55, respectively. In the annular groove 74, a ring-shaped seal member 75 that maintains airtightness between the flange-shaped portions 54 and 55 and the ring-shaped portion 52 and the dome-shaped portion 53 is disposed.

    The flange-shaped portions 54 and 55 are finally welded to each other at the outer sides of the end faces and are welded together with the welded portion 58. A groove portion 59 is formed in the outer circumferential direction at the joint between the flange-shaped portions 54 and 55 so that the brazing material can be easily deposited.

    A vibration suppressing device 60 is attached to the pressure vessel 50. The vibration suppressing device 60 includes a frame 61 fixed to the pressure vessel 50, a plate-like spring 62 supported by the frame 61, and a mass (mass) 63 supported by the spring 62.

    The interior of the piston 12 is a cavity 80. The cavity 80 communicates with the compression space 45 via a check valve 90 disposed on the end face of the piston 12. The structure of the check valve 90 will be described in detail later. On the outer peripheral surface of the piston 12, a plurality of concave portions 81 forming a gas bearing are arranged on the same circumference at a predetermined angular interval. A metal thin tube 82 is driven into the bottom of the recess 81 so as to penetrate the piston 12, and the working gas is supplied from the cavity 80 to the recess 81 through the metal thin tube 82. The annular row of the recesses 81 may be only one row, or two or more rows may be formed at intervals in the axial direction of the piston 12.

    The inside of the displacer 13 is also a cavity 85. The cavity 85 communicates with the compression space 45 via a check valve 90 disposed on the end face of the displacer 13. On the outer peripheral surface of the displacer 13, a plurality of recesses 86 forming gas bearings are arranged on the same circumference at predetermined angular intervals. The working gas is supplied from the cavity 85 to the recess 86 through the metal thin tube 87 driven into the bottom of the recess 86.

    The Stirling engine 1 operates as follows. When an alternating current is supplied to the coil 21 of the linear motor 20, a magnetic field penetrating the magnet 24 is generated between the outer yoke 22 and the inner yoke 23, and the magnet 24 reciprocates in the axial direction. A frequency that matches the resonance frequency determined by the total mass of the piston system (piston 12, magnet holder 14, magnet 24, and spring 30) and the spring constant of the spring 30 and the spring constant of the gas spring formed by the bounce space 51. By supplying electric power, the piston system starts a smooth sinusoidal reciprocating motion.

    In the displacer system (the displacer 13, the displacer shaft 15, and the spring 31), the resonance frequency determined by the total mass and the spring constant of the spring 31 is set to resonate with the driving frequency of the piston 12.

    By the reciprocating motion of the piston 12, the compression space 45 is repeatedly compressed and expanded. As the pressure changes, the displacer 13 also reciprocates. At this time, a phase difference is generated between the displacer 13 and the piston 12 due to flow resistance between the compression space 45 and the expansion space 46. In this way, the displacer 13 having a free piston structure vibrates in synchronization with the piston 12 with a predetermined phase difference.

    By the above operation, a Stirling cycle is formed between the compression space 45 and the expansion space 46. A compression change occurs in the compression space 45, and an expansion change occurs in the expansion space 46. For this reason, the temperature of the compression space 45 rises and the temperature of the expansion space 46 falls.

    When the working gas reciprocates between the compression space 45 and the expansion space 46 during operation passes through the internal heat exchangers 42 and 43, the working gas passes through the internal heat exchangers 42 and 43 and the heat transfer heads 40 and 41. To tell. Since the working gas flowing into the regenerator 47 from the compression space 45 is high temperature, the heat transfer head 40 is heated, and the heat transfer head 40 becomes a warm head. Since the working gas flowing into the regenerator 47 from the expansion space 46 is at a low temperature, the heat transfer head 41 is cooled, and the heat transfer head 41 becomes a cold head. The Stirling engine 1 functions as a refrigeration engine by dissipating heat from the heat transfer head 40 to the atmosphere and lowering the temperature of the specific space by the heat transfer head 41.

    The regenerator 47 functions to pass only the working gas without transferring the heat of the compression space 45 and the expansion space 46 to the counterpart space. The hot working gas that has entered the regenerator 47 from the compression space 45 through the internal heat exchanger 42 gives the heat to the regenerator 47 when passing through the regenerator 47, and enters the expansion space 46 in a state where the temperature is lowered. Inflow. The low-temperature working gas that has entered the regenerator 47 from the expansion space 46 through the internal heat exchanger 43 recovers heat from the regenerator 47 when passing through the regenerator 47, and enters the compression space 45 in a state where the temperature has risen. Inflow. That is, the regenerator 47 serves as a heat storage.

    When the piston 12 and the displacer 13 reciprocate and the working gas moves, the Stirling engine 1 is vibrated. The vibration suppressing device 60 suppresses this vibration.

    A part of the high-pressure working gas in the compression space 45 enters the cavity 80 of the piston 12 and the cavity 85 of the displacer 13 through the check valve 90. And it ejects from the recessed parts 81 and 86. FIG. A gas film is formed between the outer peripheral surface of the piston 12 and the inner peripheral surface of the cylinder 10 and between the outer peripheral surface of the displacer 13 and the inner peripheral surface of the cylinder 11 by the jetting working gas. And the contact between the displacer 13 and the cylinder 11 are prevented.

    If two or more gas bearings of the piston 12 and the displacer 13 are provided at an axial interval, the piston 12 is in the axial direction with respect to the cylinder 10 and the displacer 13 is in the axial direction with respect to the cylinder 11 during the reciprocating motion. It becomes difficult to tilt. Therefore, contact between the piston 12 and the cylinder 10 and between the displacer 13 and the cylinder 11 is reliably avoided, and problems such as energy loss due to friction at the contact portion or wear of the contact portion are less likely to occur.

    FIGS. 12 and 13 show the structure and mounting method of the gas bearing check valve 90 that has been used so far. 12 is an enlarged cross-sectional view of the check valve 90, and FIG. 13 is a cross-sectional view of a displacer to which the check valve is attached.

    Main elements constituting the check valve 90 are a base 91, a valve block 92, a valve body 93, and a backup plate 94. The base 91 and the valve block 92 are made of metal or synthetic resin, and are fixed to each other by screws or the like (not shown) in such a manner that the valve block 92 is placed in the center of the base 91. Of course, the base 91 and the valve block 92 are preferably integrally formed.

    The base 91 and the valve block 92 are provided with a vent hole 95 penetrating both. A valve body 93 and a backup plate 94 are placed on the outside of the valve block 92 so as to overlap each other, and both are collectively fixed to the valve block 92 with screws 96. The valve body 93 is made of a flexible thin plate such as stainless steel or polyethylene, and the vent hole 95 is closed at its free end. The backup plate 94 is for limiting the range of motion so that the valve body 93 does not bend too much, and is formed of metal or synthetic resin.

    The base 91 is formed with a large-diameter recess 95 a at the inlet of the vent hole 95. A filter 97 is inserted into the recess 95a. The base 91 is also provided with a screw through hole 98 at a location that does not overlap the valve block 92. The base 91 is fixed to the displacer 13 (or the piston 12) by a screw 99 penetrating through the screw through hole 98.

    As can be seen in FIG. 13, the check valve 90 is inserted into the hole drilled in the end face of the displacer 13, and the valve block 92 portion protrudes to the inner surface of the displacer 13. Then, the check valve 90 is fixed to the displacer 13 by tightening the screw 99 through the screw through hole 98 into the displacer 13.

    When the pressure in the compression space 45 increases, the working gas in the compression space 45 pushes the valve body 93 and flows into the cavity 85 from the vent hole 95. The working gas that has flowed into the cavity 85 is ejected into the recess 86 through the metal thin tube 87, thereby fulfilling the function of a gas bearing. Since the valve body 93 closes the vent 95 immediately after the working gas flows into the cavity 85, the working gas cannot flow backward from the vent 95. For this reason, the working gas has no exit from the cavity 85 other than the recess 86, and the gas bearing maintains its function as long as the Stirling engine 1 continues to operate.

    In the cavity 85, there is dust generated when the displacer 13 is processed or assembled, or dust generated when the Stirling engine 1 is operated. This dust approaches the check valve 90 as indicated by an arrow A in FIG. 13 due to the flow of the working gas in the cavity 85. If this bites between the valve body 93 and the valve block 92, the valve body 93 will not be completely closed. If the valve body 93 is not completely closed and the working gas leaks from the cavity 85 as shown by the arrow B in FIG. 13, the performance deteriorates due to gas flow loss. Further, when the internal pressure of the displacer 13 decreases and the gas bearing does not function, there arises a problem that the displacer 13 comes into contact with the cylinder 11 and is worn or damaged. A similar problem occurs in the piston 12.

    Therefore, in the present invention, the structure of the check valve 90 or the way of mounting the check valve 90 is devised so that the above problem does not occur. Hereinafter, this is shown in FIGS. 3 to 11 as first to eighth embodiments.

    A first embodiment is shown in FIGS. FIG. 3 is a sectional view of the check valve, and FIG. 4 is a plan view of the same.

    In the first embodiment, the periphery of the valve body 93 and the backup plate 94 is surrounded by a wall 100 for dust control. The wall 100 forms a closed loop, and the interval between the inner peripheral surface of the wall 100 and the peripheral edge of the valve body 93 is made as narrow as possible within a range that does not hinder the flow of the working gas flowing into the cavity 85 from the vent hole 95. Further, the height of the wall 100 is increased within an allowable range. The wall 100 may be integrally formed with the valve block 92, or a separate member may be fixed to the valve block 92.

    By enclosing the periphery of the valve body 93 with the wall 100 in this manner, the approach of the dust to the valve body 93 is prevented, and the dust is not caught on the valve body 93 and prevents the valve body 93 from being completely blocked. . For this reason, the working gas which has flowed into the cavity 85 from the check valve 90 flows to the gas bearing without flowing back toward the compression space 45, and the gas bearing functions completely.

    A second embodiment is shown in FIG. FIG. 5 is a plan view of the check valve.

    In the first embodiment, the valve body 93 and the backup plate 94 are both in a plane shape rectangle, and the wall 100 is also formed in a plane shape rectangle accordingly. In the second embodiment, the valve body 93 and the backup plate 94 are made into a plane shape oval, and the wall 100 is made into a plane shape oval accordingly. The planar shape of the base 91 is also oval.

    A third embodiment is shown in FIG. FIG. 6 is a sectional view of the piston.

    In 3rd Embodiment, the side wall 12a by the side of the compression space 45 of piston 12 was made thick, and the through-hole 12b was provided in this. A check valve 90 was inserted into the through-hole 12 b from the outside of the piston 12 and fixed with a screw 99. Accordingly, the check valve 90 is embedded in the through hole 12b. The check valve 90 is of the conventional type shown in FIG. Instead, the inner surface of the through-hole 12 b was used as a wall, and was brought close to the periphery of the valve body 93 to the same extent as the wall 100.

    Thus, since the check valve 90 is embedded in the through hole 12b formed in the side wall of the piston 12 and / or the displacer 13, and the inner surface of the through hole 12b is used as a dust control wall, the configuration is simplified.

    A fourth embodiment is shown in FIG. FIG. 7 is a sectional view of the piston.

    In the fourth embodiment, a part of the structure of the third embodiment is changed. That is, in the case of the third embodiment, the through hole 12b in which the check valve 90 is accommodated has a uniform thickness and has passed through the cavity 80. In the fourth embodiment, the partition wall 101 is formed at the outlet of the through hole 12b. The working gas was allowed to flow into the cavity 80 from the through hole 12b through the small hole 102 at the center. Since the partition wall 101 exists as an obstacle in this way, the dust in the cavity 80 becomes more difficult to approach the valve body 93.

    In 1st-3rd embodiment, the approach of garbage is blocked | prevented by making small the clearance gap between the valve body 93 and the wall surrounding it. For this purpose, it is necessary to strictly manage both the dimensional accuracy of the valve body 93 and the wall and the mounting accuracy of the valve body 93, but it is not easy to realize this when considering actual production and assembly. In that respect, the configuration of the fourth embodiment can design the clearance between the valve body 93 and the surrounding wall with a clearance because the obstacle called the partition wall 101 prevents dust.

    A fifth embodiment is shown in FIG. FIG. 8 is a cross-sectional view of the displacer.

    In the fifth embodiment, a dust control wall is formed on the inner surface of the displacer 13 so as to surround the check valve 90 protruding from the inner surface of the displacer 13. A cover 103 enclosing the valve block 92 constitutes a wall. The cover 103 has a small hole 104 in the center, and is fixed together with the check valve 90 by a screw 99 that penetrates the side wall of the displacer 13.

    As described above, since the dust control wall is formed on the inner surface of the displacer 13 so as to surround the check valve 90 protruding to the inner surface of the displacer 13, the check valve 90 can be protected from the dust that has entered the displacer 13. it can. Further, since the wall is constituted by the cover 103 which is a separate part from the displacer 13, the wall can be easily formed.

    In the configuration of the fifth embodiment, since the cover 103 serves as an obstacle for controlling dust, the clearance between the valve body 93 and the surrounding wall can be designed with a clearance as in the fourth embodiment.

    A sixth embodiment is shown in FIG. FIG. 9 is a cross-sectional view of the displacer.

    The sixth embodiment is obtained by adding the following improvements to the fifth embodiment. That is, the small hole 104 of the cover 103 is shifted from the center of the cover 103, and the second valve body 105 and the second backup plate 106 similar to the valve body 93 and the backup plate 94 are arranged outside thereof. As a result, the second check valve is formed where the check valve 90 is exited, and the operation of the check valve is further ensured. Of course, even if this configuration is applied to the piston 12, the same effect can be obtained.

    Even in the configuration of the sixth embodiment, since the cover 103 serves as an obstacle for controlling dust, the clearance between the valve body 93 and the surrounding wall can be designed with a space.

    A seventh embodiment is shown in FIG. FIG. 10 is a sectional view of the displacer.

    The seventh embodiment is obtained by adding the following improvements to the fifth embodiment. That is, the opening of the space surrounded by the wall, in this case, the small hole 104 of the cover 103 was closed with the filter 107 for dust control. The filter 107 is the same as the filter 97. The dust in the cavity 85 is prevented from approaching the valve body 93 by the filter 107, so that the check valve 90 does not malfunction.

    Thus, since dust is controlled by the cover 103 and the filter 107, the clearance between the valve body 93 and the surrounding wall can be designed with a space.

    An eighth embodiment is shown in FIG. FIG. 11 is a sectional view of the piston.

    The eighth embodiment is obtained by adding the following improvements to the fourth embodiment. That is, the opening of the space surrounded by the wall, in this case, the small hole 102 of the partition wall 101 was closed with the filter 107 for dust control. The filter 107 is the same as the filter 97. The dust in the cavity 80 is prevented from approaching the valve element 93 by the filter 107, so that the check valve 90 does not malfunction.

    Thus, since dust is controlled by the partition wall 101 and the filter 107, the clearance between the valve body 93 and the surrounding wall can be designed with a space.

    In each of the above embodiments, the structure described by taking the piston 12 as an example can be applied to the displacer 13 as it is. Conversely, the structure described by taking the displacer 13 as an example can be applied to the piston 12 as it is. For the check valve 90, only the structure in which the valve body 93 is formed of a flexible thin plate is shown, but the structure of the valve body 93 is not limited to this. A configuration in which a flat lid is pressed against the vent hole 95 with a compression coil spring, or a configuration in which a stopper having a taper on the outer periphery is pressed against the vent hole 95 with a compression coil spring can be employed.

    In FIG. 1, the piston 12 and the displacer 13 are depicted as having a divided structure. This is in consideration of the convenience in providing the check valve 90, the cover 103, the filter 107, and the like inside the piston 12 and the displacer 13. The design concept of such a divided structure is applied regardless of the embodiment.

    Each embodiment of the present invention has been described above, but various modifications can be made without departing from the spirit of the present invention.

    The present invention is applicable to all free piston type Stirling engines.

Cross section of Stirling engine 1 is an enlarged view of the main part of FIG. Sectional drawing of the non-return valve which concerns on 1st Embodiment of this invention. Plan view of the check valve of FIG. The top view of the non-return valve which concerns on 2nd Embodiment of this invention. Sectional drawing of the piston which concerns on 3rd Embodiment of this invention. Sectional drawing of the piston which concerns on 4th Embodiment of this invention. Sectional drawing of the displacer which concerns on 5th Embodiment of this invention. Sectional drawing of the displacer which concerns on 6th Embodiment of this invention. Sectional drawing of the displacer concerning 7th Embodiment of this invention Sectional drawing of the piston which concerns on 8th Embodiment of this invention. Cross section of a conventional check valve Cross section of conventional displacer

Explanation of symbols

1 Stirling engine 10, 11 cylinder 12 piston 13 displacer 90 check valve 100 wall 103 cover 107 filter

Claims (6)

A piston that is reciprocated by a power source and a displacer that reciprocates with a predetermined phase difference with respect to the piston are provided. These pistons and / or displacers are supported in a cylinder by gas bearings. And / or in a Stirling engine in which the displacer is provided with a check valve for taking in the working gas for the gas bearing,
A Stirling engine characterized in that the valve body of the check valve is surrounded by a dust control wall.   The Stirling engine according to claim 1, wherein the check valve is embedded in a through hole formed in a side wall of the piston and / or the displacer, and the inner surface of the through hole is used as a dust control wall.   The dust check wall is formed on the inner surface of the piston and / or the displacer so that the check valve protrudes from the inner surface of the piston and / or the displacer and surrounds the check valve. The listed Stirling organization.   The Stirling engine according to claim 3, wherein the wall is constituted by a cover which is a separate part from the piston and / or the displacer.   The Stirling engine according to claim 4, wherein a second check valve is provided in the vent hole of the cover.   The Stirling engine according to any one of claims 1 to 5, wherein an opening of a space surrounded by the wall is closed with a dust control filter.

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