JP5017217B2 - Switching valve and regenerative refrigerator - Google Patents

Description

  The present invention relates to a switching valve, in particular, a switching valve used in a regenerative refrigerator that generates cryogenic cold, and a regenerative refrigerator that uses this switching valve.

  The regenerative refrigerator is a method of supplying and exhausting refrigerant gas into the refrigerator cylinder, using a Stirling type refrigerator that sends the pressure waveform generated by the reciprocating motion of the piston directly into the refrigerator cylinder, and a compressor. There are two types of Gifford-McMahon (hereinafter referred to as GM) type in which compressed high-pressure refrigerant is switched and supplied and exhausted by a switching valve provided between the compressor and the refrigerator cylinder.

  The latter system consists of a rotary valve that is mechanically driven as a switching valve, a spool valve (a single spool valve that switches supply / exhaust by movement of one spool, and a double spool valve that supplies and exhausts air using separate spool valves. There are systems such as electromagnetic valves that are electrically driven. Each has advantages and disadvantages.

  The rotary valve is normally rotated by pressing the rotor made of resin or the like against the stator by gas pressure or spring pressure, and the refrigerant flows in a state where the supply and exhaust holes provided in the rotor and the stator are in agreement with each other. In the state, control that does not flow the refrigerant is performed in a cycle. Normally, the sliding surface is pressed down by the surface pressure, so the amount of leakage when the refrigerant stops can be reduced, but wear due to sliding occurs, and there is a demerit in terms of durability or reliability due to wear powder. There is.

  In a single spool valve, a cylinder called a spool disposed in the valve cylinder is reciprocated by a rotating cam, and the refrigerant flows in a state where the hole on the valve cylinder and the spool groove on the spool are aligned. Control without flowing the refrigerant is performed in cycles. In other words, as shown in FIG. 7, this single spool valve is provided with an air supply hole 101 and an exhaust hole 102 in the valve cylinder 100 at different positions in the axial direction. A path 105 is formed, and the spool 103 is reciprocated by the rotation of the cam 106, the spool groove 104 and the air supply hole 101 or the exhaust hole 102 are matched, and supply and exhaust are switched. Reference numeral 107 denotes a cam rotation shaft, and reference numeral 108 denotes a spring.

  In this single spool valve, unlike the rotary valve system, the valve cylinder 100 and the spool 103 are in contact with a gap of several μm to several tens of μm in the absence of surface pressure. However, wear is less compared to rotary valves. On the other hand, since the leak is held in the gap, there is a possibility that the amount of leak is large or galling occurs due to dust or the like sandwiched between the gaps.

  As described in Patent Documents 1 and 2, the double spool valve is a system in which the basic configuration of the spool valve is the same as that of the single spool valve, and the two spool valves are driven by different cams. That is, one spool valve is provided with an air supply hole in its valve cylinder for supplying air, and the other spool valve is provided with an exhaust hole in its valve cylinder for exhausting air.

  For this reason, although the degree of freedom of supply and exhaust valve timings is high, since the cams that drive the spools are doubled, the cold head of the refrigerator that accommodates the two spool valves becomes large. If the diameter of the spool valve is reduced for compactness, the flow passage cross-sectional area of the supply / exhaust cannot be sufficiently secured, and the performance deteriorates due to pressure loss. Further, this double spool valve has the same durability as the single spool valve, but the probability of trouble is twice that of the single spool valve.

The above-described three types of valves (rotary valve, single spool valve, double spool valve) are systems in which the valve is mechanically driven in synchronism with the displacer by a motor that drives the displacer of the refrigerator. The valve method is a method of supplying and exhausting air by an electromagnetic valve that is electrically switched. The biggest merit is that the timing of supply and exhaust can be changed during operation of the refrigerator, but although it is suitable for research purposes, there is a problem with the durability of the solenoid valve, and it is adopted for commercial refrigerators It has not been done.
JP-A-63-21451 Japanese Patent Laid-Open No. 4-139357

  Regarding the switching valve that periodically supplies and exhausts fluid, in the single spool valve as described above, the cam 106 that drives the spool 103 has a circular shape. Therefore, the valve timing of supply and exhaust is as shown in FIG. However, there is a limitation that the timing becomes symmetrical in time. In particular, in a regenerative refrigerator using this switching valve, the time t1 from the completion of supply to the start of exhaust and the time t2 from completion of exhaust to the start of supply become equal, and the valve timing of supply and exhaust determines the refrigeration cycle. There is a disadvantage that the degree of freedom is lower than other methods.

  An object of the present invention is made in consideration of the above-described circumstances, and provides a switching valve that is excellent in compactness, durability, and low-pressure loss characteristics, and that can improve the degree of freedom of switching timing of a flow path. is there.

  Another object of the present invention is to provide a regenerative refrigerator that can optimize the refrigeration efficiency by improving the degree of freedom of supply and exhaust valve timing.

  A switching valve according to the present invention includes a single valve cylinder, a single spool that can reciprocate in the valve cylinder, and a cam that drives the spool. In the switching valve for switching a plurality of flow paths by matching a plurality of holes formed in the moving direction with a groove formed on the outer periphery of the spool, the cam for driving the spool includes a plurality of cams, The cam is characterized in that the direction of eccentricity with respect to the cam rotation shaft is different.

  The switching valve according to the present invention includes a single valve cylinder, a single spool that can reciprocate within the valve cylinder, and a cam that drives the spool. In the switching valve that switches a plurality of flow paths by matching a plurality of holes formed in the spool moving direction with grooves formed on the outer periphery of the spool, the cam for driving the spool is a single cam. And the shape of this cam is an oval shape formed by shifting the centers of the two circles so as to overlap each other and forming two tangent lines in contact with the two circles and the circumference of the two circles. The direction of each straight line connecting the centers of the two cams and the cam rotation shaft is set differently.

  The regenerator type refrigerator according to the present invention further includes a cold head and a refrigerant supply / exhaust system including a compressor for compressing the refrigerant. The cold head reciprocates between the refrigerator cylinder and the refrigerator cylinder. A displacer that moves and forms a first volume fluctuation chamber and a second volume fluctuation chamber with the refrigerator cylinder, and is formed in the displacer and communicates the first volume fluctuation chamber and the second volume fluctuation chamber. And a switching valve that switches between supply of refrigerant from the compressor to the first volume fluctuation chamber and discharge of refrigerant from the first volume fluctuation chamber to the compressor. In the regenerative refrigerator that generates cryogenic cold by expanding the refrigerant that has passed through the regenerator and cooled to the second volume fluctuation chamber by the displacer, An exchange hole is comprised from the switching valve of any one of Claims 1 thru | or 4, and the intake hole for supplying the refrigerant | coolant from the said compressor as intake air in the valve cylinder of this switching valve And an exhaust hole for discharging the refrigerant in the refrigerator cylinder as exhaust to the compressor is formed in the moving direction of the spool.

  According to the switching valve and the regenerative refrigerator according to the present invention, the switching timing of the plurality of flow paths switched by the switching valve can be independently changed by changing the eccentric direction of the plurality of cams driving the spool with respect to the cam rotation shaft. Since it can be adjusted, the degree of freedom of this switching timing can be improved. As a result, when this switching valve is applied to a regenerative refrigerator, the degree of freedom in supply and exhaust valve timing can be improved, so that the refrigerating efficiency of this refrigerator can be optimized. Further, since the switching of the plurality of flow paths is performed by a single switching valve (single spool valve) using a spool, the compactness, durability and pressure loss characteristics of the switching valve can be improved.

  Further, according to the switching valve and the regenerative refrigerator according to the present invention, the switching valve is changed by changing the direction of each straight line connecting the center of the two circles constituting the elliptical cam and the cam rotation shaft. Since the switching timing of the plurality of flow paths switched by the above can be adjusted independently, the degree of freedom of the switching timing can be improved. As a result, when this switching valve is applied to a regenerative refrigerator, the degree of freedom in supply and exhaust valve timing can be improved, so that the refrigerating efficiency of this refrigerator can be optimized. Further, since the switching of the plurality of flow paths is performed by a single switching valve (single spool valve) using a spool, the compactness, durability and pressure loss characteristics of the switching valve can be improved.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

[A] First embodiment (FIGS. 1 to 5)
FIG. 1 is a schematic configuration diagram showing a regenerator type refrigerator to which a first embodiment of a switching valve according to the present invention is applied. 2 shows a state where the switching valve in FIG. 1 is switched to the intake side, (A) is a front sectional view, and (B) is a side sectional view.

  As shown in FIG. 1, a regenerative refrigerator 10 is a Gifford-McMahon (GM) refrigerator that generates a cryogenic temperature (for example, 30 K or less), and has a cold head 11 and a refrigerant supply / exhaust system 12. The refrigerant supply / exhaust system 12 includes a compressor 13 that compresses the refrigerant. Here, any one of helium 3, helium 4, neon, and hydrogen is used as the refrigerant.

  The cold head 11 includes a refrigerator cylinder 14, a displacer 15, a cool storage material 16, a switching valve 17, and a drive motor 18.

  The displacer 15 reciprocates in the refrigerator cylinder 14 to partition a buffer chamber 19 as a first volume variation chamber and an expansion chamber 20 as a second volume variation chamber with the refrigerator cylinder 14. Form.

The cool storage material 16 cools the refrigerant by heat exchange, and is disposed in a communication path 21 formed in the displacer 15. The communication passage 21 is formed so as to penetrate the displacer 15 and communicate the buffer chamber 19 and the expansion chamber 20. As the regenerator material 16, a magnetic regenerator material having a large specific heat at a very low temperature, such as rare earth compounds such as Er ₃ Ni (erbium 3 nickel) and HoCu ₂ (holmium kappa 2), or ceramics is used.

  The switching valve 17 switches between supply of refrigerant from the compressor 13 to the buffer chamber 19 and discharge of refrigerant from the buffer chamber 19 to the compressor 13. This switching valve 17 switches the flow path in conjunction with the reciprocating movement of the displacer 15, and when the displacer 15 is in the vicinity of the bottom dead center (the state of FIG. 1), the refrigerant from the high pressure side of the compressor 13 is supplied to the inlet. 22 is supplied as intake air to the buffer chamber 19, and when the displacer 15 is before and after the top dead center, the refrigerant in the buffer chamber 19 is exhausted and discharged to the low pressure side of the compressor 13 through the outlet 23. The inlet 22 and the outlet 23 are opened in a motor case 24 provided integrally with the refrigerator cylinder 14. As will be described in detail later, the switching valve 17 is constituted by a single spool valve (single spool valve).

  The drive motor 18 is housed in a motor case 24, and a cam rotation shaft 25 is coupled to the motor shaft of the drive motor 18 so as to rotate together. A displacer drive cam 26 and a valve drive cam 27 (described later) for the switching valve 17 are coupled to the cam rotation shaft 25 in an integral manner. A bearing 28 is externally fitted to the displacer driving cam 26, and the displacer driving cam 26 is fitted to a connecting rod 29 connected to the displacer 15 via the bearing 28.

  When the drive motor 18 is operated, the valve drive cam 27 rotates to reciprocate a spool 32 (described later) of the switching valve 17, and the displacer drive cam 26 is rotated to reciprocate the displacer 15 via the connecting rod 29. . By the reciprocating movement of the displacer 15, the refrigerant in the buffer chamber 19 is cooled by the cold storage material 16 and reaches the expansion chamber 20, and is expanded in the expansion chamber 20, thereby generating a cryogenic cold. At this time, in the expansion chamber 20, the expansion pressure is reduced to a critical pressure or lower of the refrigerant, and the refrigerant is liquefied. The cold is generated using the latent heat of the liquefied refrigerant. This cold is given to the load through the cooling stage 30 of the refrigerator cylinder 14.

  In the above-described regenerative refrigerator 10, when the displacer 15 is near the bottom dead center (lowermost position) of the refrigerator cylinder 14, the refrigerant from the high pressure side of the compressor 13 is sucked into the buffer chamber 19 by the switching valve 17. Supplied as Then, in the process in which the displacer 15 moves from the bottom dead center to the top dead center (uppermost position) in the refrigerator cylinder 14, the refrigerant in the buffer chamber 19 is cooled by the cool storage material 16 in the communication passage 21, and the inside of the expansion chamber 20. Flow into. In the process in which the displacer 15 moves to the top dead center of the refrigerator cylinder 14, the volume of the expansion chamber 20 increases.

  The refrigerant in the buffer chamber 19 is discharged to the low pressure side of the compressor 13 by the switching valve 17 before and after the displacer 15 reaches the top dead center of the refrigerator cylinder 14. As a result, the refrigerant expands and liquefies in the expansion chamber 20 as described above, and cryogenic cold is generated by the latent heat.

  Thereafter, in the process of moving the displacer 15 to the bottom dead center, the refrigerant in the expansion chamber 20 reaches the buffer chamber 19 through the communication path 21 while cooling the cool storage material 16, and passes through the switching valve 17 and the motor case 24. And discharged to the low pressure side of the compressor 13. By repeating the above, the cooling stage 30 of the refrigerator cylinder 14 is cooled to a very low temperature, and this very low temperature is applied to the load.

  As shown in FIGS. 2 and 3, the switching valve 17 includes a single valve cylinder 31, a single spool 32 that can reciprocate in the valve cylinder 31, and the spool 32 that drives the spool 32. The valve drive cam 27 includes a spring 37 that applies a biasing force to the spool 32 so that the spool 32 is always in contact with the valve drive cam 27.

  In the valve cylinder 31, a plurality of holes formed in the moving direction of the spool 32 (that is, the intake holes 33 and the exhaust holes 34) are formed in the spool 32 by matching with the spool grooves 35 formed on the outer periphery of the spool 32. A plurality of flow paths (that is, the intake-side flow path and the exhaust-side flow path) are switched through the spool internal flow path 36.

  As shown in FIGS. 1 and 2, the intake hole 33 is a valve for supplying refrigerant on the high pressure side of the compressor 13 as intake air to the buffer chamber 19 through the spool groove 35 and the spool passage 36 of the spool 32. It is formed in the cylinder 31. The intake side flow path passes through the high pressure side of the compressor 13 through the inlet 22 of the motor case 24, the intake hole 33 of the valve cylinder 31, the spool groove 35 of the spool 32, and the flow path 36 in the spool. This is a flow path communicating with the buffer chamber 19.

  Further, the exhaust hole 34 is formed in the valve cylinder 31 in order to discharge the refrigerant in the buffer chamber 19 of the refrigerator cylinder 14 to the low pressure side of the compressor 13 through the in-spool flow path 36 and the spool groove 35 of the spool 32. It has been done. The exhaust side flow path passes through the buffer chamber 19 through the in-spool flow path 36 and spool groove 35 of the spool 32, the exhaust hole 34 of the valve cylinder 31, the motor case 24, and the outlet 23 of the motor case 24. 13 is a flow path communicating with the low pressure side.

  In the switching valve 17 configured as described above, the valve drive cam 27 is rotationally driven in synchronization with the displacer drive cam 26 by, for example, a drive motor 18 that rotates at a constant rotational speed. FIG. 2 shows a state in which the valve drive cam 27 pushes down the spool 32 to the lowermost side, and the intake hole 33 of the valve cylinder 31 and the spool groove 35 of the spool 32 coincide with each other. In this state, the intake hole 33 of the valve cylinder 31 and the buffer chamber 19 of the refrigerator cylinder 14 communicate with each other, and the intake hole 33 communicates with the high pressure side of the compressor 13. High-pressure refrigerant from the compressor 13 is introduced into the buffer chamber 19 of the refrigerator cylinder 14 as intake air. The flow direction of the refrigerant at this time is indicated by an arrow A.

  On the other hand, FIG. 3 shows a state in which the valve drive cam 27 is rotated 180 degrees from the state of FIG. 2 and the spool 32 is pushed up most by the urging force of the spring 37. The groove 35 is in a matched state. In this state, the exhaust hole 34 of the valve cylinder 31 and the buffer chamber 19 of the refrigerator cylinder 14 communicate with each other, and the exhaust hole 34 communicates with the low pressure side of the compressor 13. The refrigerant in the buffer chamber 19 of the machine cylinder 14 is discharged to the low pressure side of the compressor 13 as exhaust. The flow direction of the refrigerant at this time is indicated by an arrow B.

  As described above, the refrigerant intake and exhaust processes by the switching valve 17 are performed in conjunction (that is, synchronized) with a predetermined phase difference with respect to the reciprocating movement of the displacer 15, and during one rotation of the valve drive cam 27, FIG. As shown, the position A1 to the position A2 are an intake process in which the intake side flow path is opened, and the position A3 to a position A4 is an exhaust process in which the exhaust side flow path is opened. When the displacer 15 reaches near the bottom dead center, the refrigerant suction process into the buffer chamber 19 is started (position A1), and before and after the displacer 15 reaches the top dead center, the refrigerant exhaust in the buffer chamber 19 is exhausted. The process is started (position A3).

  By the way, the valve drive cam 27 is composed of a plurality of (two in the present embodiment) disk-shaped cams 27A and 27B coupled to a single cam rotating shaft 25, and each of these cams 27A, 2B, the eccentric directions PA and PB with respect to the cam rotation shaft 25 are formed differently as shown in FIG. That is, by setting the cam rotation shaft 25 at a position other than the straight line L connecting the center OA of the cam 27A and the center OB of the cam 27B, the cam 27A connecting the center OA of the cam 27A and the cam rotation shaft 25 is set. The eccentric direction PA is different from the eccentric direction PB of the cam 27B that connects the center OB of the cam 27B and the cam rotation shaft 25, and an angle θ (θ ≠ 0) is generated between the eccentric directions PA and PB.

  Therefore, by changing the position of the center OA of the cam 27A and the center OB of the cam 27B and / or changing the position of the cam rotation shaft 25 with respect to the center OA of the cam 27A and the center OB of the cam 27B, The eccentric direction PA and the eccentric direction PB of the cam 27B are changed. Thereby, the switching timing of the intake side flow path and the exhaust side flow path switched by the switching valve 17, that is, the refrigerant intake and exhaust valve timing (specifically, the intake angle (time) α1 shown in FIG. The angle (time) α2, the exhaust angle (time) α3, and the angle (time) α4 from the completion of exhaust to the start of intake are able to be adjusted independently.

  As shown in FIG. 5B, assuming that the cam rotation shaft 25 is set on a straight line L connecting the center OA of the cam 27A and the center OB of the cam 27B, the eccentric direction PA of the cam 27A and the cam 27B Are in the same direction. In this state, the range where the arc M representing the condition for opening the intake side flow path intersects the outer shape of the cam 27A is the intake process (intake angle α1), and the arc N representing the condition for opening the exhaust side flow path and the cam 27B. The range where the outer shape intersects is the exhaust process (exhaust angle α3).

  At this time, since the eccentric direction PA of the cam 27A and the eccentric direction PB of the cam 27B are the same direction, the positions of the center OA of the cam 27A, the center OB of the cam 27B, and the cam rotation shaft 25 are changed to Even if the angle (time) α1 and the exhaust angle (time) α3 are adjusted, the angle (time) α2 from the completion of intake to the start of exhaust and the angle (time) α4 from the completion of exhaust to the start of exhaust have the same value (angle, Time) and the intake and exhaust valve timings cannot be adjusted independently.

  In contrast, in FIG. 5A, the cam rotation shaft 25 is set at a position other than the straight line L connecting the center OA of the cam 27A and the center OB of the cam 27B, and the eccentric direction PA of the cam 27A and the cam 27B are set. The case where the eccentric direction PB is made different is shown. Even in this state, the range where the arc M representing the condition for opening the intake side flow path and the outer shape of the cam 27A is the intake process (intake angle α1), and the arc N representing the condition for opening the exhaust side flow path and the cam 27B. The range where the outer shape intersects is the exhaust process (exhaust angle α3).

  However, in this case, the intake angle (time) α1 and the exhaust angle (time) α3 are independently set by changing the positions of the center OA of the cam 27A, the center OB of the cam 27B, and the cam rotation shaft 25. In addition to the adjustment, the angle (time) α2 from the completion of intake to the start of exhaust and the angle (time) α4 from the completion of exhaust to the start of intake can be adjusted independently. Specifically, in a refrigeration cycle involving liquefaction, the intake flow (refrigerant) with a small flow rate is increased in a short time during the intake process, and the exhaust process is started at an appropriate timing, thereby refrigeration while minimizing the refrigerant flow rate. High-efficiency operation without reducing the capacity can be realized.

  As shown in FIG. 2, a bearing 38 as a sliding restraining mechanism for restraining sliding with the spool 32 is fitted on the outer circumferences of the cams 27 </ b> A and 27 </ b> B constituting the valve driving cam 27. ing. The inner ring of the bearing 38 is rotated by the rotation of the cams 27A and 27B, and the outer ring contacts the spool 32 without rotating, so that the cams 27A and 27B and the spool 32 slide even when the cams 27A and 27B rotate. Is suppressed.

  Therefore, according to the present embodiment, the following effects (1) to (3) are obtained.

  (1) In the switching valve 17, the eccentric directions PA and PB of the two cams 27A and 27B that drive the spool 32 with respect to the cam rotation shaft 25 are set differently, and switching is performed by changing these eccentric directions PA and PB. Since the switching timing of the intake side flow path and the exhaust side flow path switched by the valve 17 can be adjusted independently, the degree of freedom of this switching timing can be improved. As a result, when the switching valve 17 is applied to the regenerative refrigerator 10, the supply / exhaust valve timing (intake angle (time) α1, angle from completion of intake to start of exhaust (time) α2, exhaust angle (time) Since the degree of freedom of α3, the angle (time) α4) from the completion of exhaust to the start of intake can be improved, the refrigeration efficiency of this refrigerator can be optimized.

  Normally, an angle (time) α2 from the completion of intake to the start of exhaust and an angle (time) α4 from the completion of exhaust to the start of intake are sections in which the switching valve 17 is closed. In the section in which the switching valve 17 is closed, the refrigerating cycle of the regenerator refrigerator 10 is such that the displacer 15 moves upward or downward with the inside of the refrigerator cylinder 14 closed, and the temperature gradient of the displacer 15 This is an important process regarding the refrigeration efficiency of the regenerator refrigeration machine 10, accompanied by a pressure change caused by. For example, in the section of the angle (time) α2 from the completion of intake to the start of exhaust, mainly, the displacer 15 moves upward, the pressure in the expansion chamber 20 of the refrigerator cylinder 14 decreases, and the intake starts from the end of exhaust. Until the angle (time) α4 until, the displacer 15 moves downward and the pressure in the expansion chamber 20 of the refrigerator cylinder 14 increases.

  Therefore, the valve timings of the intake angle (time) α1, the angle (time) α2 from the completion of intake to the start of exhaust, the exhaust angle (time) α3, and the angle (time) α4 from the completion of exhaust to start of intake are independently adjusted. By doing so, the refrigerating efficiency of the regenerator type refrigerator 10 can be optimized in accordance with the refrigerant pressure by the compressor 13 and the cold temperature to be generated, and the performance of the regenerator type refrigerator 10 can be improved.

  (2) Since the switching between the intake side flow path and the exhaust side flow path is performed by the single switching valve 17 (single spool valve) using the spool 32, the switching valve 17 as a whole can be made compact and switched. The cold head 11 of the regenerative refrigerator 10 that accommodates the valve 17 can be downsized. In addition, since it is a single spool valve, the number of parts can be reduced compared to the double spool valve, the cost can be reduced, the probability of trouble is reduced, and the durability of the switching valve 17 as a whole is improved. Can do. Furthermore, since the flow passage cross-sectional areas of the intake hole 33, the exhaust hole 34, and the in-spool flow path 36 in the switching valve 17 can be sufficiently secured, the low pressure loss characteristic can also be improved.

  (3) A bearing 38 is fitted on the outer periphery of the cams 27A and 27B of the valve drive cam 27, and the cams 27A and 27B come into contact with the spool 32 via the bearing 38, and the rotating cams 27A and 27B are brought into contact with the spool 32. Since it does not contact, sliding between the cams 27A and 27B and the spool 32 can be suppressed.

[B] Second embodiment (FIG. 6)
6A and 6B show a second embodiment of a switching valve according to the present invention, in which FIG. 6A is a front sectional view and FIG. 6B is a partial side view. In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description is simplified or omitted.

  The switching valve 40 of the present embodiment is different from the switching valve 17 of the first embodiment in that the valve drive cam 27 is changed to a cam having a shape other than a disk shape, for example, a single cam 41 having an oval shape. And a bearing 42 as a sliding restraining member is installed on the spool 32 side via a pedestal 43.

  That is, the cam 41 is overlapped by shifting the centers QA and QB of the two circles (cams) 41A and 41B, and the two tangents R and S contacting the circles 41A and 41B and the outer circumferences of the circles 41A and 41B. It is formed in an oval shape. Further, in this cam 41, the cam rotation shaft 25 is set at a position other than on the straight line L connecting the center QA of the circle 41A and the center QB of the circle 41B. Thereby, the direction of the straight line KA connecting the center QA of the cam 41 and the cam rotation shaft 25 and the direction of the straight line KB connecting the center QB of the circle 41B and the cam rotation shaft 25 are set differently, and both straight lines KA and KB are set. An angle δ (δ ≠ 0) is set between them.

  Also in the case of this cam 41, by changing the direction of the straight line KA and the direction of the straight line KB, the switching valve 40 driven by the cam 41 switches the intake side flow path and the exhaust side flow path, In other words, intake and exhaust valve timing (intake angle (time) α1, angle from completion of intake to exhaust start (time) α2, exhaust angle (time) α3, angle from exhaust completion to start of intake (time) α4) are independent. And can be adjusted.

  Further, since the outer shape of the cam 41 is not circular, the bearing 42 is rotatably attached to the spool 32 using a pedestal 43, and the bearing 42 contacts the outer periphery of the cam 41. Also in the case of this bearing 42, only the bearing 42 is rotated by the rotation of the cam 41, and the spool 32 does not come into contact with the cam 41, so that sliding between the spool 32 and the cam 41 is suppressed.

  Therefore, according to the present embodiment, in addition to the same effects (1) to (3) as in the first embodiment, the following effect (4) is achieved.

  (4) Since the bearing 42 for suppressing the sliding between the cam 41 and the spool 32 is provided on the spool 32 side, the drive motor 18 (FIG. 1) that applies a rotational force to the cam 41 when the bearing 42 is replaced. There is no need to remove the bearing 42 and the replacement work of the bearing 42 can be facilitated.

  As mentioned above, although this invention was demonstrated based on the said embodiment, this invention is not limited to this. For example, although the regenerator type refrigerator 10 of the present embodiment has been described as the GM type in which the switching valve 17 is installed in the cold head 11, the GM type in which the switching valve 17 is installed in or near the cold head 11. A pulse tube refrigerator may be used.

  The regenerative refrigerator 10 may be one in which the refrigerator cylinder 14 and the displacer 15 are installed in two or more stages, and further, a precooling stage (precooling heat exchanger) in which the displacer 15 is cooled by another refrigerator or the like. It may be a precooling type refrigerator equipped with.

The schematic block diagram which shows the cool storage type refrigerator with which 1st Embodiment of the switching valve which concerns on this invention was applied. The state which the switching valve of FIG. 1 switched to the intake side is shown, (A) is front sectional drawing, (B) is side sectional drawing. FIG. 2 is a front sectional view showing a state where the switching valve in FIG. 1 is switched to the exhaust side. The graph which shows the valve timing of the supply / exhaust by the switching valve of FIG.2 and FIG.3. FIG. 2A is an explanatory diagram for explaining the procedure for setting the switching timing of the switching valve when the eccentric directions of the two cams in the valve drive cams of FIGS. 2 and 3 are different, and FIG. Explanatory drawing explaining the setting procedure of the switching timing of a switching valve, when the eccentric directions are the same. The 2nd Embodiment of the switching valve which concerns on this invention is shown, (A) is front sectional drawing, (B) is a partial side view. Front sectional drawing which shows the conventional switching valve. The graph which shows the valve timing of the supply / exhaust by the switching valve of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Cold storage type refrigerator 11 Cold head 12 Refrigerant supply / exhaust system 13 Compressor 14 Refrigerator cylinder 15 Displacer 16 Cold storage material 17 Switching valve 18 Drive motor 19 Buffer chamber (first volume fluctuation chamber)
20 Expansion chamber (second volume fluctuation chamber)
21 Communicating Path 25 Cam Rotating Shaft 27 Valve Drive Cam 27A, 27B Cam 31 Valve Cylinder 32 Spool 33 Intake Hole 34 Exhaust Hole 35 Spool Groove 38 Bearing (Sliding Suppression Mechanism)
40 switching valve 41 cam 41A, 41B circle 42 bearing (sliding suppression mechanism)
PA, PB Eccentric direction QA, QB Center R, S Tangent

Claims (8)

A single valve cylinder, a single spool capable of reciprocating in the valve cylinder, and a cam for driving the spool;
In the switching valve for switching a plurality of flow paths by matching a plurality of holes formed in the moving direction of the spool in the valve cylinder with a groove formed in the outer periphery of the spool,
The switching valve according to claim 1, wherein the cam for driving the spool includes a plurality of cams, and each cam is configured to have a different eccentric direction with respect to the cam rotation shaft. 2. The switching according to claim 1, wherein the plurality of cams are formed in a circular shape, and a sliding suppression mechanism is provided on an outer periphery of each of the cams to suppress sliding between the cams. valve. A single valve cylinder, a single spool capable of reciprocating in the valve cylinder, and a cam for driving the spool;
In the switching valve for switching a plurality of flow paths by matching a plurality of holes formed in the moving direction of the spool in the valve cylinder with a groove formed in the outer periphery of the spool,
The cam for driving the spool is a single cam, and the shape of the cam is shifted by overlapping the centers of two circles, two tangent lines in contact with these two circles, and the circumference of the two circles And an oval shape formed by
A switching valve characterized in that the directions of the respective straight lines connecting the centers of the two cams and the cam rotation shaft are set differently. The switching valve according to claim 3, wherein a sliding restraining mechanism for restraining sliding between the cam and the spool is provided on a spool side in contact with the elliptical cam. A cold head and a refrigerant supply / exhaust system having a compressor for compressing the refrigerant;
The cold head includes a refrigerator cylinder,
A displacer that reciprocates in the refrigerator cylinder and forms a first volume variation chamber and a second volume variation chamber with the refrigerator cylinder;
A regenerator material formed in the displacer and disposed in a communication passage communicating the first volume variation chamber and the second volume variation chamber;
A switching valve that switches between supply of refrigerant from the compressor into the first volumetric variation chamber and discharge of refrigerant from the first volumetric variation chamber to the compressor;
In the regenerative refrigerator that generates the cryogenic cold by expanding the refrigerant that has passed through the regenerator and cooled to the second volume fluctuation chamber by the displacer,
The switching valve is composed of the switching valve according to any one of claims 1 to 4,
An intake hole for supplying refrigerant from the compressor as intake air to the valve cylinder of the switching valve; and an exhaust hole for discharging refrigerant in the refrigerator cylinder as exhaust to the compressor. Is formed in the moving direction of the spool. 6. The cold storage according to claim 5, wherein in the second volume fluctuation chamber, the expansion pressure is reduced to a critical pressure or less, the refrigerant is liquefied during the expansion, and cold is generated using the latent heat. Type refrigerator. 6. The regenerative refrigerator according to claim 5, wherein any one of helium 3, helium 4, neon, and hydrogen is used as the refrigerant. The regenerative refrigerator according to claim 5, wherein a magnetic regenerator material such as a rare earth compound or ceramics is used as the regenerator material.

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