JP2006292135A - Gas bearing structure and Stirling engine and Stirling cooler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas bearing structure with improved workability and gas sealability, and a Stirling engine and a Stirling cooler provided with the structure.
A gas bearing structure is a gas bearing structure that supports a piston 14 that reciprocates in a cylinder, and includes a groove portion that is intermittently formed in an outer peripheral surface 141 of the piston 14 along a circumferential direction of the piston 14. A “gas ejection mechanism” that ejects gas from the inner space 147 toward the inner circumferential surface of the cylinder through the ejection hole 144 reaching the inner space 147 of the piston 14 from the bottom surface 143A is provided. The groove is formed so as to reach the outer peripheral surface 141 of the piston 14.
[Selection] Figure 5

Description

  The present invention relates to a gas bearing structure, a Stirling engine, and a Stirling Refrigerator / Freezer, and more particularly, to a gas bearing structure with improved workability and gas sealability, and a Stirling engine and a Stirling cooler having the structure. And about.

  A gas bearing structure of a piston is conventionally known.

  For example, in Japanese Patent Application Laid-Open No. 2004-293792, the working gas that flows into the gas storage chamber is inserted into the outer wall of a piston that is fitted in the cylinder filled with the working gas and reciprocates and that has the gas storage chamber inside. There is disclosed a gas bearing structure of a piston constituted by providing a communicating hole member in which a communicating hole for ejecting toward the inner wall is formed. Here, a recess is provided on the outer wall, and a communicating hole member is provided on the bottom surface of the recess. By providing the communication hole on the bottom surface of the recess, deformation of the outer peripheral surface of the piston during hole formation is suppressed. Thereby, the function as a bearing structure improves.

Japanese Patent No. 3583770 discloses that a hollow portion is provided in a displacer or a displacer rod that reciprocates on the same axis as a piston in a Stirling engine.
JP 2004-293792 A Japanese Patent No. 3583770

  However, the gas bearing structure as described above has the following problems.

  In Japanese Patent Application Laid-Open No. 2004-293792, a cylindrical recess or a belt-like recess is provided on the outer peripheral surface of the piston. Here, the process for providing the cylindrical recess has poor processability. On the other hand, if a strip-shaped recess is provided, the amount of gas leakage in the axial direction of the piston increases. As a result, for example, when the piston is provided in the gas compression / expansion machine, the performance of the gas compression / expansion machine decreases.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a gas bearing structure with improved workability and gas sealability, and a Stirling engine and a Stirling cooler having the structure. And to provide.

  The gas bearing structure according to the present invention includes a cylindrical portion, a columnar portion having a gas chamber therein, and reciprocating along the inner wall of the cylindrical portion, and an outer peripheral surface of the columnar portion in the circumferential direction of the columnar portion. A gas ejection mechanism that ejects gas from the gas chamber toward the inner peripheral surface of the cylindrical portion through the hole portion that reaches the gas chamber from the bottom surface of the groove portion that is intermittently formed along the bottom surface, In at least one direction, the groove is formed so as to be continuous (intersect) with the outer peripheral surface of the columnar portion adjacent to the groove without any step. Here, the bottom surface may be formed in a flat shape or a curved surface (arc surface). In addition, the bottom surface of the groove and the outer peripheral surface of the columnar part are continuous without any step in “at least one direction” as described above. For example, when the bottom surface of the groove is formed in a concave spherical shape, the bottom surface of the groove and the columnar part The outer peripheral surface of the portion is continuous in “omnidirectional” with no step. In other words, the “one direction” can be referred to as a “bottom direction of processing”. The “one direction” is generally considered to coincide with, for example, the circumferential direction or the axial direction of the columnar portion, but the “one direction” is an oblique direction intersecting the circumferential direction and the axial direction. There may be.

  According to the said structure, since the crossing angle of the bottom face of a groove part and the outer peripheral surface of a columnar part becomes an obtuse angle, workability improves. When the “bottom direction (cutting direction)” is the circumferential direction of the columnar portion, the amount of gas leakage in the axial direction can be reduced, and the gas sealing performance in the gas bearing structure can be improved.

  In the gas bearing structure, it is preferable that a plurality of gas ejection mechanisms are formed at equiangular intervals so as to be aligned in the circumferential direction of the columnar part. Thereby, the gas bearing structure which hold | maintains a columnar part stably can be obtained.

  In the gas bearing structure, it is preferable that the gas ejection mechanisms are staggered in the axial direction. Thereby, the movement of the columnar part in the cylindrical part can be further stabilized.

  In the gas bearing structure, it is preferable to form a hole portion in the gas ejection mechanism by assembling a tube to a hole reaching the gas chamber from the outer peripheral surface of the columnar portion. As a result, it is possible to provide finer holes and reduce the loss by narrowing the flow rate.

  A Stirling engine according to the present invention is a Stirling engine including the gas bearing structure, and includes an outer shell, a cylinder assembled in an outer shell enclosing a working medium, a piston reciprocating in the cylinder, and a cylinder A displacer that reciprocates with respect to the piston with a phase difference, a displacer rod that is connected to the displacer and penetrates the piston in the axial direction, a compression space formed between the piston and the displacer, and a piston side with respect to the displacer An expansion space formed on the opposite side of the piston, a back pressure space formed on the opposite side of the displacer side with respect to the piston, and a regenerator disposed in a communication passage that connects the compression space and the expansion space. The gas ejection mechanism is provided on the piston, the displacer or the displacer rod. This provides a high performance and relatively inexpensive Stirling engine.

  In one aspect, in the Stirling engine, preferably, the gas ejection mechanism in the gas bearing structure is formed separately on the back pressure space side and the compression space side in the piston, and the gas provided on the back pressure space side of the piston The number of ejection mechanisms is made smaller than the number of gas ejection mechanisms provided on the compression space side of the piston. As a result, the number of processing steps can be reduced and the amount of gas leakage in the axial direction of the piston can be reduced. As a result, the gas sealing performance is improved.

  In another aspect, in the Stirling engine, preferably, the gas ejection mechanism in the gas bearing structure is formed separately on the back pressure space side and the compression space side in the piston, and the gas provided on the back pressure space side of the piston The diameter of the hole in the ejection mechanism is made smaller than the diameter of the hole in the gas ejection mechanism provided on the compression space side of the piston. Thereby, the amount of gas leakage in the axial direction of the piston can be reduced, and as a result, the gas sealing performance is improved.

  A Stirling refrigerator according to the present invention includes the Stirling engine. Thereby, a high-performance and relatively inexpensive Stirling cooler can be provided.

  According to the present invention, the workability and gas sealability of the gas bearing structure can be improved.

  Embodiments of a gas bearing structure, a Stirling engine, and a Stirling cooler according to the present invention will be described below.

  In the present specification, the “cooling box” is a concept including all of “refrigerator”, “freezer”, and “freezer refrigerator”.

  In the first and second embodiments, a Stirling refrigerator as a Stirling engine and a Stirling refrigerator as a Stirling engine-equipped device equipped with the Stirling refrigerator will be described. The Stirling engine is originally a Stirling refrigerator. For example, it is used also as a generator.

(Embodiment 1)
FIG. 1 is a piping system diagram of a Stirling cooler according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the Stirling refrigerator 1 includes a Stirling refrigerator 4 (Stirling engine) having a high temperature part 2 and a low temperature part 3, a high temperature side evaporator 5 attached to the high temperature part 2, and a high temperature side condenser. 7 and the first high temperature side circulation circuit (first circulation circuit) including the pipes 2A and 2B, and the second high temperature side circulation circuit including the high temperature side evaporator 5, the circulation pump 6, the dew prevention pipe 9 and the pipes 2C to 2E ( 2nd circulation circuit) and the low temperature side circulation circuit containing the low temperature side condenser 10 attached to the low temperature part 3, the low temperature side evaporator 11, and the pipes 3A and 3B. The first high temperature side circulation circuit cools the high temperature part 2 of the Stirling refrigerator 4, and the second high temperature side circulation circuit supplies heat to the dew condensation prevention pipe 9. The low temperature side circulation circuit performs heat exchange between the air in the refrigerator and the low temperature part 3 of the Stirling refrigerator 4.

Water (H ₂ O) or the like is sealed as a refrigerant in the first and second high temperature side circulation circuits. The refrigerant evaporated in the high temperature side evaporator 5 reaches the high temperature side condenser 7 via the pipe 2A (high temperature side conduit) (broken line arrow in FIG. 1). The refrigerant is condensed by heat exchange with the outside air in the high temperature side condenser 7. In order to promote this heat exchange, a fan 8 that generates an air flow in the vicinity of the high-temperature side condenser 7 is provided. The condensed refrigerant returns to the high temperature side evaporator 5 through the pipe 2B (high temperature side return pipe). In the first high temperature side circulation circuit, the heat generated in the high temperature part 2 can be transferred to the high temperature side condenser 7 by utilizing the natural circulation caused by the evaporation and condensation of the refrigerant. The side condenser 7 is disposed above the high temperature side evaporator 5. Further, in order to adjust the boiling point of the refrigerant, the pressure in the circulation circuit system is adjusted (reduced pressure from atmospheric pressure).

  On the other hand, a pipe 2 </ b> C is connected to the lower part of the high temperature side evaporator 5. Liquid phase refrigerant flows from the high temperature side evaporator 5 into the pipe 2C. The refrigerant flowing into the pipe 2 </ b> C reaches the circulation pump 6 provided below the Stirling refrigerator 4. The refrigerant discharged from the circulation pump 6 is sent to the dew prevention pipe 9 via the pipe 2D. Here, the refrigerant flowing in the dew condensation prevention pipe 9 is kept at a relatively high temperature by the heat given from the high temperature part 2 of the Stirling refrigerator 4. Therefore, the dew condensation prevention pipe 9 can be arranged in the front opening of the refrigerator to suppress the dew condensation at the door portion or the like. The refrigerant that has flowed through the dew condensation prevention pipe 9 returns to the high temperature side evaporator 5 through the pipe 2E. Thus, forced circulation by the circulation pump 6 is performed in the second high temperature side circulation circuit.

  Carbon dioxide, hydrocarbons, and the like are sealed as refrigerant in the low temperature side circulation circuit. The refrigerant condensed in the low temperature side condenser 10 reaches the low temperature side evaporator 11 through the pipe 3A (low temperature side conduit). Heat exchange is performed by evaporating the refrigerant in the low temperature side evaporator 11. In order to promote this heat exchange, a fan 12 that generates an air flow in the vicinity of the low-temperature evaporator 11 is provided. After the heat exchange, the gasified refrigerant returns to the low temperature side condenser 10 through the pipe 3B (low temperature side return pipe). In the low-temperature side circulation circuit, the low-temperature side evaporation is performed so that the cold heat generated in the low-temperature part 3 can be transmitted to the low-temperature side evaporator 11 by utilizing natural circulation caused by the evaporation and condensation of the refrigerant. The vessel 11 is disposed below the low temperature side condenser 10. Further, the pressure in the circulation circuit system is adjusted in order to adjust the boiling point of the refrigerant.

  When the Stirling refrigerator 4 is operated, heat generated in the high temperature part 2 of the refrigerator 4 is exchanged with air through the high temperature side condenser 7. On the other hand, the cold generated in the low temperature part 3 of the Stirling refrigerator 4 is heat exchanged with the air in the refrigerator through the low temperature side evaporator 11. The warmed airflow from the inside of the refrigerator is sent again to the vicinity of the low-temperature side evaporator 11 and repeatedly cooled.

  With the implementation of the cooling cycle described above, frost forms on the low temperature side evaporator 11. Since a well-known technique can be used for the defrosting method for this frost formation, detailed description will not be given.

  By performing the defrosting described above, defrosted water is generated. The defrost water is guided to the drain pan 12B (evaporating dish) installed at the lower part of the bottom surface of the refrigerator main body through the drain pipe 12A. A fan 12C is provided in the vicinity of the drain pan 12B, and an air flow is formed near the surface of the defrost water accumulated in the drain pan 12B by the fan 12C, and relatively dry air is supplied onto the defrost water. , Evaporation of defrost water is promoted.

  Next, an example of the structure of the Stirling refrigerator 4 and its operation will be described with reference to FIG.

  As shown in FIG. 2, the Stirling refrigerator 4 of the present embodiment is a free piston type Stirling engine, and includes a casing 30, a cylinder 13 assembled to the casing 30, and a reciprocating motion in the cylinder 13. Piston 14 and displacer 15, regenerator 16, working space 17 including a compression space 17 </ b> A and an expansion space 17 </ b> B, a high temperature portion 2, a low temperature portion 3, a linear motor 23 as a piston driving means, and a piston spring 24, a displacer spring 25, a displacer rod 26, and a back pressure space 27.

  In the example of FIG. 2, the outer shell (outer wall) of the Stirling refrigerator 4 is not constituted by a single container, but is positioned on the back pressure space 27 side and the casing 30 (vessel portion) and on the working space 17 side. The high-temperature part 2, the tube 18A, and the low-temperature part 3 are mainly configured. The casing 30 defines a back pressure space 27. Various parts including the cylinder 13, the linear motor 23, the piston spring 24, and the displacer spring 25 are assembled to the casing 30. The outer shell is filled with a working medium such as helium gas, hydrogen gas, or nitrogen gas.

  The cylinder 13 has a substantially cylindrical shape, and receives therein a piston 14 and a displacer 15 as a free piston so as to be capable of reciprocating. In the cylinder 13, the piston 14 and the displacer 15 are coaxially spaced apart, and the piston 14 and the displacer 15 divide the working space 17 in the cylinder 13 into a compression space 17 </ b> A and an expansion space 17 </ b> B. More specifically, the working space 17 is a space located closer to the displacer 15 than the end face of the piston 14 on the displacer 15 side, and a compression space 17A is formed between the piston 14 and the displacer 15, and the displacer 15 and the low temperature portion 3, an expansion space 17 </ b> B is formed. The compression space 17A is mainly surrounded by the high temperature part 2, and the expansion space 17B is mainly surrounded by the low temperature part 3.

  Between the compression space 17 </ b> A and the expansion space 17 </ b> B, a regenerator 16 in which a film is wound on the outer peripheral surface of the cylinder 13 with a predetermined gap is disposed. Thus, the compression space 17A and the expansion space 17B communicate with each other. Thereby, a closed circuit is formed in the Stirling refrigerator 4. The working medium sealed in the closed circuit flows in accordance with the operations of the piston 14 and the displacer 15, thereby realizing a reverse Stirling cycle described later.

  A linear motor 23 is disposed in the back pressure space 27 located outside the cylinder 13. The linear motor 23 includes an inner yoke 20, a movable magnet portion 21, an outer yoke 22 and a coil, and the piston 14 is driven in the axial direction of the cylinder 13 by the linear motor 23.

  One end of the piston 14 is connected to a piston spring 24 constituted by a leaf spring or the like. The piston spring 24 functions as an elastic force applying means for applying an elastic force to the piston 14. By applying an elastic force to the piston spring 24, the piston 14 can be reciprocated in the cylinder 13 more stably and periodically. One end of the displacer 15 is connected to a displacer spring 25 via a displacer rod 26. The displacer rod 26 is disposed through the piston 14, and the displacer spring 25 is constituted by a leaf spring or the like. The peripheral edge of the displacer spring 25 and the peripheral edge of the piston spring 24 are supported by a support member that extends from the linear motor 23 toward the back pressure space 27 of the piston 14 (hereinafter sometimes referred to as the rear).

A back pressure space 27 surrounded by a casing 30 is disposed on the opposite side of the piston 14 from the displacer 15. The back pressure space 27 includes an outer peripheral region located around the piston 14 in the casing 30 and a rear region located closer to the piston spring 24 (rear side) than the piston 14 in the casing 30. There is also a working medium in the back pressure space 27.

  The high temperature part 2 is attached to the casing 30 via the base member 30A. The high temperature part 2 and the low temperature part 3 are connected via the tube 18A. On the inner peripheral surfaces of the high temperature part 2 and the low temperature part 3, an internal heat exchanger 18 and an internal heat exchanger 19 are provided, respectively. The internal heat exchangers 18 and 19 perform heat exchange between the compression space 17A and the expansion space 17B and the high temperature part 2 and the low temperature part 3, respectively.

  A balance mass 29 is attached to the rear side of the casing 30 via a leaf spring 28. The balance mass 29 is a mass member that absorbs vibration of the casing 30 that is generated when the piston 14 and the displacer 15 vibrate. Specifically, when the vibration is generated in the casing 30 due to the vibration of the piston 14 or the displacer 15, the balance mass 29 is vibrated so as to follow the vibration of the casing 30, whereby the Stirling refrigerator 4. Vibration is reduced.

  Next, the operation of the Stirling refrigerator 4 will be described.

  First, the linear motor 23 is actuated to drive the piston 14. The piston 14 driven by the linear motor 23 approaches the displacer 15 and compresses the working medium (working gas) in the compression space 17A.

  When the piston 14 approaches the displacer 15, the temperature of the working medium in the compression space 17 </ b> A rises, but heat generated in the compression space 17 </ b> A by the high temperature portion 2 is released to the outside. Therefore, the temperature of the working medium in the compression space 17A is maintained almost isothermal. That is, this process corresponds to an isothermal compression process in a reverse Stirling cycle.

  After the piston 14 approaches the displacer 15, the displacer 15 moves to the low temperature part 3 side. On the other hand, the working medium compressed in the compression space 17A by the piston 14 flows into the regenerator 16, and further flows into the expansion space 17B. At that time, the heat of the working medium is stored in the regenerator 16. That is, this process corresponds to an isovolumetric cooling process in a reverse Stirling cycle.

  The high-pressure working medium that has flowed into the expansion space 17B expands when the displacer 15 moves to the piston 14 side (rear side). As the displacer 15 moves rearward in this way, the center portion of the displacer spring 25 is also deformed so as to protrude rearward.

  When the working medium expands in the expansion space 17B as described above, the temperature of the working medium in the expansion space 17B decreases, but external heat is transferred into the expansion space 17B by the low temperature portion 3, The inside of the expansion space 17B is kept almost isothermal. That is, this process corresponds to an isothermal expansion process of a reverse Stirling cycle.

  Thereafter, the displacer 15 starts to move away from the piston 14 (front side). Thereby, the working medium in the expansion space 17B passes through the regenerator 16 and returns to the compression space 17A side again. At this time, since the heat stored in the regenerator 16 is applied to the working medium, the working medium is heated. That is, this process corresponds to a constant volume heating process of a reverse Stirling cycle.

  By repeating this series of processes (isothermal compression process-isovolume cooling process-isothermal expansion process-isovolume heating process), an inverse Stirling cycle is configured. As a result, the low temperature part 3 is gradually lowered in temperature and has an extremely low temperature (for example, about −50 ° C.). On the other hand, the high temperature part 2 becomes gradually high temperature (for example, about 60 ° C.). As described above, the cold heat in the low temperature section 3 is supplied into the refrigerator through the low temperature side circulation circuit, and the heat in the high temperature section 2 is released to the outside of the refrigerator through the first and second high temperature side circulation circuits. Is done.

  FIG. 3 is a perspective view showing an example of the piston 14 included in the “gas bearing structure” according to the present embodiment. 4 and 5 are an IV-IV sectional view and a VV sectional view in FIG. 3, respectively. 3 to 5, the piston 14 has a hollow shape having an internal space 147. The piston 14 has an outer peripheral surface 141 and an axial end surface 142. A groove portion 143 having a bottom surface 143A is formed on the outer peripheral surface 141 of the piston 14, and an ejection hole 144 for ejecting gas from the internal space 147 in the direction of the arrow OUT is formed on the bottom surface 143A. The gas is ejected from the ejection hole 144, whereby the piston 14 is held in a non-contact state with the inner wall of the cylinder 13. Here, the groove part 143 and the ejection hole 144 form a “gas ejection mechanism”. By providing such a “gas ejection mechanism”, sliding resistance when the piston 14 reciprocates in the cylinder 13 is reduced. An inflow hole 145 reaching the internal space 147 is formed on the axial end surface 142 (on the compression space 17 </ b> A side) of the piston 14. The gas flowing from the compression space 17A into the internal space 147 of the piston 14 flows in the direction of the arrow IN through the inflow hole 145. Thereby, the gas required for the “gas ejection mechanism” is supplied. The “gas bearing structure” that holds the piston 14 that reciprocates in the cylinder 13 is configured as described above. The piston 14 has a rod insertion portion 146 that receives the displacer rod 26.

  As shown in FIG. 3, a plurality of “gas ejection mechanisms” including the groove portion 143 and the ejection holes 144 are formed so as to be aligned in the circumferential direction of the piston 14 (the arrow DR2 direction). In other words, the groove 143 is formed intermittently along the circumferential direction of the piston 14.

  As shown in FIG. 4, a check valve 148 is provided at the end of the inflow hole 145 on the inner space 147 side. The valve opening direction of the check valve 148 is an arrow DR3 direction. That is, the check valve 148 suppresses the flow that flows out from the internal space 147 of the piston 14 to the outside of the piston 14 while allowing the flow into the internal space 147 of the piston 14 from the outside of the piston 14. Thereby, the pressure in the internal space 147 can be stably kept relatively high. In other words, the gas used for the gas bearing can be stably stored in the internal space 147.

  As shown in FIG. 5, the plurality of ejection holes 144 are formed at equal angular intervals of 90 ° in the circumferential direction of the piston 14 (arrow DR2 direction). In other words, in the example shown in FIG. 5, the four ejection holes 144 are formed at equiangular intervals along the circumferential direction of the piston 14. Further, the bottom surface 143 </ b> A of the groove is formed so as to be continuous with the outer peripheral surface 141 without a step in the circumferential direction of the piston 14. In other words, the bottom surface 143 </ b> A of the groove is formed so as to be continuous (intersect) with the outer peripheral surface 141 without a step in the circumferential direction of the piston 14.

  In the above configuration, by providing the gas injection hole 144 on the bottom surface 143A of the groove part 143 that is a concave part, deformation of the outer peripheral surface of the piston 14 during processing for forming the injection hole 144 is suppressed. Furthermore, in the “gas bearing structure”, the gas ejected from the ejection hole 144 is filled in the groove 143, and the piston 14 can be supported in a relatively wide area. Thereby, the function as the “bearing structure” is improved. Further, by forming the groove 143 intermittently along the circumferential direction of the piston 14, it is possible to suppress a decrease in gas sealing performance in the axial direction of the piston 14. Further, in the circumferential direction of the piston 14, the groove portion 143 is formed so that the bottom surface 143 </ b> A of the groove portion 143 and the outer peripheral surface 141 of the piston 14 are continuous (intersect) without a step, so that in the axial direction and the circumferential direction of the piston 14. In comparison with the case where the concave portion having a step is formed, processing at the time of forming the concave portion (groove portion 143) is facilitated. If a two-axis machine tool is used, two parts can be excised at the same time, and the processing time can be further reduced. That is, according to the “gas bearing structure” according to the present embodiment, the function as the “bearing structure”, the gas sealing performance in the axial direction of the piston 14 and the workability of the piston 14 can be satisfied at the same time.

  6 and 7 are axial cross-sectional views (cross-sectional views corresponding to FIG. 5) showing modifications of the gas ejection mechanism shown in FIGS. 3 to 5, respectively. Referring to FIGS. 6 and 7, the plurality of ejection holes 144 may be formed at three equal angular intervals of 120 ° in the circumferential direction (arrow DR2 direction) of the piston 14 or at equal angular intervals of 180 °. Two may be formed.

  FIG. 8 is a perspective view showing another modification of the gas ejection mechanism. As shown in FIG. 8, the “gas ejection mechanism” including the groove 143 and the ejection holes 144 may be arranged in a staggered manner in the axial direction of the piston 14. By doing in this way, even when the number of the ejection holes 144 is small, the movement of the piston 14 in the cylinder 13 can be made more stable. Note that the “gas ejection mechanisms” may be arranged in a staggered manner in the circumferential direction of the piston 14.

  FIG. 9 is a sectional side view showing still another modification of the gas ejection mechanism. As shown in FIG. 9, a gas ejection hole 144 may be formed using a metal communication pipe 149. In other words, in this modification, the ejection hole 144 included in the “gas ejection mechanism” is formed by assembling the communication pipe 149 to the hole reaching the internal space 147 from the outer peripheral surface 141 of the piston 14. Thereby, the diameter of the ejection hole 144 can be made smaller, and the loss can be reduced by narrowing the flow rate. Further, by using a metal tube, electrostatic charging around the ejection hole 144 is suppressed, and as a result, adhesion of dust and the like is suppressed. Therefore, the flow path of the ejection hole 144 can be secured stably.

  In the above description, an example of a “gas bearing structure” in which a piston 14 that reciprocates in the cylinder 13 is provided with a “gas ejection mechanism” has been described, but the same idea applies to a displacer 15 that reciprocates in the cylinder 13. Alternatively, the present invention may be applied to the displacer rod 26 that reciprocates within the rod insertion portion 146 of the piston 14.

  FIG. 10 is a side sectional view showing the displacer 15 and the displacer rod 26 when the same idea as the “gas bearing structure” described above is applied to the displacer 15 and the displacer rod 26.

  As shown in FIG. 10, the displacer 15 has a hollow shape having an internal space 157. The displacer 15 has an outer peripheral surface 151 and an axial end surface 152. A groove portion 153 having a bottom surface 153A is formed on the outer peripheral surface 151 of the displacer 15, and an ejection hole 154 for ejecting gas from the internal space 157 in the direction of the arrow OUT is formed on the bottom surface 153A. The gas is ejected from the ejection hole 154, whereby the displacer 15 is held in a non-contact state with the inner wall of the cylinder 13. Here, the groove 153 and the ejection hole 154 form a “gas ejection mechanism”. By providing such a “gas ejection mechanism”, sliding resistance when the displacer 15 reciprocates in the cylinder 13 is reduced. An inflow hole 155 reaching the internal space 157 is formed on the axial end surface 152 (on the compression space 17 </ b> A side) of the displacer 15. The gas flowing from the compression space 17A into the inner space 157 of the displacer 15 flows in the direction of the arrow IN through the inflow hole 155. Thereby, the gas required for the “gas ejection mechanism” is supplied. The “gas bearing structure” that holds the displacer 15 that reciprocates in the cylinder 13 is configured as described above.

  Further, the flow that flows out from the internal space 157 of the displacer 15 to the outside of the displacer 15 is allowed at the end of the inflow hole 155 on the side of the internal space 157 while allowing the flow into the internal space 157 of the displacer 15 from the outside. A check check valve is provided (not shown). Thereby, the pressure in the internal space 157 can be stably kept relatively high. In other words, the gas used for the gas bearing can be stably stored in the internal space 157.

  The displacer rod 26 connected to the displacer 15 has a hollow shape having an internal space 267 communicating with the internal space 157. The displacer rod 26 has an outer peripheral surface 261. A groove 263 having a bottom surface 263A is formed on the outer peripheral surface 261 of the displacer rod 26, and an ejection hole 264 for ejecting gas from the internal space 267 is formed on the bottom surface 263A. As the gas is ejected from the ejection hole 264, the displacer rod 26 is held in a non-contact state with the inner wall of the rod insertion portion 146 of the piston 14. Here, the groove part 263 and the ejection hole 264 form a “gas ejection mechanism”. By providing such a “gas ejection mechanism”, sliding resistance when the displacer rod 26 reciprocates in the rod insertion portion 146 is reduced. Here, the gas necessary for the “gas ejection mechanism” is supplied from the internal space 157 of the displacer 15. As described above, the “gas bearing structure” that holds the displacer rod 26 that reciprocates in the rod insertion portion 146 of the piston 14 is configured.

  Also in the example shown in FIG. 10, the bottom surfaces 153A and 263A of the groove portions are formed intermittently along the circumferential direction of the displacer 15 and the displacer rod 26 (the direction of the arrow DR2), respectively. The outer peripheral surfaces 151 and 261 are formed so as to be continuous without a step. In other words, the bottom surfaces 153A and 263A of the groove portions are formed so as to intersect the outer peripheral surfaces 151 and 261 without any step in the circumferential direction of the displacer 15 and the displacer rod 26, respectively. By doing in this way, there exists an effect similar to the "gas bearing structure" of piston 14 mentioned above.

  The above contents are summarized as follows. That is, the gas bearing structure according to the present embodiment is a gas bearing structure included in the Stirling refrigerator 4, and includes a cylinder 13 (cylindrical portion) and a piston 14 (columnar shape) that reciprocates along the inner wall of the cylinder 13. And the bottom surface 143A of the groove 143 formed intermittently on the outer circumferential surface 141 of the piston 14 along the circumferential direction of the piston 14 (direction of the arrow DR2), and the jet reaching the internal space 147 (gas chamber) of the piston 14 A "gas ejection mechanism" that ejects gas from the internal space 147 toward the inner peripheral surface of the cylinder 13 through the hole 144 (hole portion), and the outer peripheral surface 141 of the piston 14 in which the bottom surface 143A of the groove portion 143 is adjacent to the groove portion 143. The groove 143 is formed so as to intersect with the step without any difference. Note that “cylinder 13 / displacer 15” or “rod insertion portion 146 / displacer rod 26 of piston 14” may be applied as the combination of the “tubular portion / columnar portion”.

  In other words, the Stirling refrigerator 4 according to the present embodiment is a “Stirling engine” including the “gas bearing structure”, and an outer shell body including a casing 30 and an outer shell body enclosing a working medium. Are connected to the displacer 15 and penetrated in the axial direction. The piston 13 reciprocating in the cylinder 13, the displacer 15 reciprocating with a phase difference with respect to the piston 14 in the cylinder 13, and the displacer 15. The displacer rod 26, the compression space 17A formed between the piston 14 and the displacer 15, the expansion space 17B formed on the opposite side of the piston 14 with respect to the displacer 15, and the compression space 17A and the expansion space 17B. And a regenerator 16 disposed in a communication path communicating with the piston 14 or Interior 147,157,267 and the "gas injection mechanism" is provided Isupuresa 15 or displacer rods 26.

  In the present embodiment, the case where the same number of “gas ejection mechanisms” is provided in the portion located on the compression space 17A side and the portion located on the back pressure space 27 side of the piston 14 has been mainly described. The number of “gas ejection mechanisms” provided in the portion located on the back pressure space 27 side may be smaller than the number of “gas ejection mechanisms” provided in the portion located on the compression space 17A side (for example, the compression space side). : 4 pieces, back pressure space side: 3 pieces). In the Stirling refrigerator 4, since the volume of the back space 27 is larger than the volume of the compression space 17A, the pressure fluctuation of the back space 27 is smaller than the pressure fluctuation of the compression space 17A. That is, even when the piston 14 moves in the direction of the back pressure space 27, the pressure in the back pressure space 27 is relatively unlikely to rise, and the pressure difference between the internal space 147 and the back pressure space 27 can be kept relatively large. Therefore, gas is easily ejected from the “gas ejection mechanism” on the back pressure space 27 side. Therefore, even if the number of “gas ejection mechanisms” provided in the portion located on the back pressure space 27 side is reduced, the function as a gas bearing structure can be sufficiently achieved. As a result, it is possible to reduce the amount of gas leak in the axial direction of the piston while ensuring the function of the gas bearing. Instead of reducing the number of “gas ejection mechanisms”, the diameter of the ejection holes 144 constituting the “gas ejection mechanism” on the back pressure space side may be set relatively small.

(Embodiment 2)
FIG. 11 is a perspective view showing an example of the piston 14 included in the “gas bearing structure” according to the second embodiment. 12 and 13 are a sectional view taken along line XII-XII and a sectional view taken along line XIII-XIII in FIG. 11, respectively. Referring to FIGS. 11 to 13, the gas bearing structure according to the present embodiment is a modification of the gas bearing structure according to the first embodiment, and in the axial direction of piston 14 (in the direction of arrow DR1), the groove portion The groove portion 143 is formed such that the bottom surface 143A of 143 is continuous (intersects) with the outer peripheral surface 141 of the piston 14 adjacent to the groove portion 143 without a step.

  As shown in FIG. 12, the bottom surface 143A of the groove 143 is formed in an arc shape. And in the arrow DR1 direction, it continues with the outer peripheral surface 141 of the piston 14 without a level | step difference.

  Also in the present embodiment, as in the first embodiment, a “gas bearing structure” excellent in workability and gas sealability can be obtained.

  Although the embodiments of the present invention have been described above, it is planned from the beginning to appropriately combine the characteristic portions of the respective embodiments described above. For example, the bottom surface 143A of the groove 143 is formed in a concave spherical shape, and the bottom surface 143A of the groove 143 is adjacent to the groove 143 in all directions including the axial direction (arrow DR1 direction) and the circumferential direction (arrow DR2 direction) of the piston. The groove 143 may be formed so as to be continuous (intersect) with the outer peripheral surface 141 of the piston 14 without a step. The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a piping system diagram of the Stirling cooler according to the first embodiment of the present invention. It is sectional drawing which shows the Stirling refrigerator in the Stirling refrigerator which concerns on Embodiment 1 of this invention. It is a perspective view which shows an example of the gas ejection mechanism in the gas bearing structure contained in the Stirling refrigerator shown by FIG. It is IV-IV sectional drawing in FIG. It is VV sectional drawing in FIG. It is sectional drawing which shows the modification of the gas ejection mechanism shown by FIGS. It is sectional drawing which shows the other modification of the gas ejection mechanism shown by FIGS. It is a perspective view which shows the other modification of the gas ejection mechanism shown by FIGS. It is sectional drawing which shows the further another modification of the gas ejection mechanism shown by FIGS. It is sectional drawing which shows an example of a displacer and a displacer rod in the Stirling refrigerator shown by FIG. It is a perspective view which shows an example of the gas ejection mechanism which concerns on Embodiment 2 of this invention. It is XII-XII sectional drawing in FIG. It is XIII-XIII sectional drawing in FIG.

Explanation of symbols

  1 Stirling cooler, 2 high temperature section, 2A-2E pipe (high temperature side circulation circuit), 3 low temperature section, 3A, 3B pipe (low temperature side circulation circuit), 4 Stirling refrigerator, 5 high temperature side evaporator, 6 circulation pump, 7 High-temperature side condenser, 8 fans, 9 Condensation prevention pipe, 10 Low-temperature side condenser, 11 Low-temperature side evaporator, 12 Fan, 12A Drain pipe, 12B Drain pan, 12C Fan, 13 Cylinder, 14 Piston, 15 Displacer, 16 Regeneration , 17 working space, 17A compression space, 17B expansion space, 18, 19 internal heat exchanger, 18A tube, 20 inner yoke, 21 movable magnet, 22 outer yoke, 23 linear motor, 24 piston spring, 25 displacer spring, 26 Displacer rod, 27 back Space, 28 leaf spring, 29 balance mass, 30 casing, 30A base member, 141, 151, 261 outer peripheral surface, 142, 152 axial end surface, 143, 153, 263 groove, 143A, 153A, 263A bottom surface, 144, 154 H.264 injection hole, 145, 155 inflow hole, 146 rod insertion part, 147, 157, 267 internal space, 148 check valve, 149 communication pipe, DR1 piston / displacer axial direction, DR2 piston / displacer circumferential direction, DR3 valve opening direction .

Claims (6)

A tubular part;
A columnar part having a gas chamber therein and reciprocating along the inner wall of the cylindrical part;
Gas from the gas chamber toward the inner peripheral surface of the cylindrical portion through a hole reaching the gas chamber from the bottom surface of a groove portion intermittently formed along the circumferential direction of the columnar portion on the outer peripheral surface of the columnar portion. A gas ejection mechanism for ejecting
A gas bearing structure in which the groove portion is formed such that a bottom surface constituting the groove portion is continuous with at least one direction with an outer peripheral surface of the columnar portion adjacent to the groove portion without a step.   The gas bearing structure according to claim 1, wherein the gas ejection mechanisms are staggered in the axial direction. A Stirling engine including the gas bearing structure according to claim 1 or 2,
The outer shell,
A cylinder assembled in the outer shell enclosing the working medium;
A piston that reciprocates within the cylinder;
A displacer that reciprocates with a phase difference with respect to the piston in the cylinder;
A displacer rod connected to the displacer and extending axially through the piston;
A compression space formed between the piston and the displacer;
An expansion space formed on the opposite side of the piston to the displacer;
A back pressure space formed on the side opposite to the displacer with respect to the piston;
A regenerator disposed in a communication path communicating the compression space and the expansion space;
A Stirling engine in which the gas ejection mechanism is provided in the piston, the displacer, or the displacer rod. The gas jetting mechanism in the gas bearing structure is formed by separating the back pressure space side and the compression space side in the piston,
The Stirling engine according to claim 3, wherein the number of the gas ejection mechanisms provided on the back pressure space side of the piston is smaller than the number of the gas ejection mechanisms provided on the compression space side of the piston. The gas jetting mechanism in the gas bearing structure is formed by separating the back pressure space side and the compression space side in the piston,
The diameter of the hole in the gas ejection mechanism provided on the back pressure space side of the piston is smaller than the diameter of the hole in the gas ejection mechanism provided on the compression space side of the piston. The listed Stirling organization.   A Stirling cooler comprising the Stirling engine according to any one of claims 3 to 5.

Images