Rotary valve for refrigerator

Abstract

To provide a rotary valve for a refrigerator having a structure which can stabilize surface pressure acting on a slide face of a stator.SOLUTION: A rotary valve for a refrigerator comprises a valve housing 6, a stator 7 fixed into the housing, a rotor 8 which faces the stator in the valve housing, and a motor M for slidably rotating the rotor with respect to the stator around a center axial line Cl passing a slide face 7a of the stator on which the rotor abuts. A first passage L1 and a plurality of second passages L2 are formed at the stator, and a third passage L3 and a fourth passage L4 are formed at the rotor. The rotary valve also comprises preload application means Cs for imparting a preload as the slide surface pressure of the side face, power transmission means 9, 93 interposed between a rotating shaft of the motor and the rotor, and transmitting rotation torque to the rotor, and absorption means Br for absorbing a corresponding reaction force when slide surface pressure higher than the preload of the slide face acts.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a rotary valve for a refrigerator. [Background technology]

[0002] In nuclear magnetic resonance diagnostic devices and physical property measuring devices, various types of refrigerators, such as pulse tube refrigerators and GM refrigerators, are used to create an extremely low temperature environment. Such refrigerators are generally equipped with a rotary valve to circulate a working gas that has been subjected to pressure oscillation. A rotary valve for this type of refrigerator is known, for example, from Patent Document 1.

[0003] This device includes a valve housing, in which a stator is mounted in an airtight manner via a sealing member such as an O-ring. A rotor is also disposed in the valve housing facing the stator, and slidably rotatably relative to the stator around a central axis passing through the sliding surface of the stator with which the rotor abuts. In this case, the rotor is connected via a first connecting pin to a rotor holder supported by a bearing provided in the valve housing, and the rotor holder is connected via a second connecting pin to a rotating member that is directly attached to a rotating shaft of a motor located on the central axis. A coil spring is compressed between the rotor and the rotor holder. When the rotor is slidably rotated in one direction by the motor, a high-pressure side passage that supplies high-pressure working gas compressed by the compressor to components of the refrigerator such as a pulse tube via the valve housing and a low-pressure side passage that recovers low-pressure working gas that has been reduced in pressure due to expansion in the components to the compressor are periodically switched.

[0004] In the above-mentioned conventional example, a force caused by the low-pressure working gas acts on the sliding surface of the stator from below, and a force caused by the high-pressure working gas in the rotor and valve housing acts on the sliding surface of the stator from above, and the difference between these forces applies a certain preload (the rotor's surface pressure applied to the stator's sliding surface) to the rotor toward the sliding surface of the stator. At this time, since the stator in the valve housing has a degree of freedom of movement in the central axis direction (thrust direction), when the rotor is rotated in one direction by the drive motor, the rotor's surface pressure acting on the sliding surface fluctuates periodically. Moreover, when a reaction force in the thrust direction caused by the rotor's sliding rotation acts on the rotor, the motor's rotating shaft receives this force, so in this case too, the rotor's surface pressure applied to the stator's sliding surface fluctuates. As described above, in the conventional examples, not only is it impossible to maintain a constant surface pressure, which is determined as an appropriate value based on the relationship between the leakage rate of the working gas and the amount of wear of the rotor, but if the average surface pressure is increased to take fluctuations into account, the rotor will wear out and its lifespan will be shortened, and there is a risk that the reaction force will act, causing the drive motor to break down or shorten its lifespan. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-203644 A Summary of the Invention [Problem to be solved by the invention]

[0006] In view of the above, an object of the present invention is to provide a rotary valve for a refrigerator having a structure capable of stabilizing the surface pressure acting on the sliding surface of a stator. [Means for solving the problem]

[0007] In order to achieve the above object, a rotary valve for a refrigerator of the present invention includes a valve housing, a stator fixed within the valve housing, a rotor made of a different material from the stator and arranged inside the valve housing directly opposite the stator, and a motor that slides and rotates the rotor relative to the stator about a central axis that passes through a sliding surface of the stator with which the rotor abuts, the stator is formed with a first passage located on the central axis through which a high-pressure gas flows, and a plurality of second passages extending along the central axis around the first passage, the rotor is formed with a third passage communicating with the first passage, and a fourth passage selectively communicating with the second passage when the rotor is slidably rotated from a state in which the second passage communicates with an internal passage of the valve housing, the rotary valve further includes a preload applying means for applying a preload as a sliding surface pressure of the sliding surface, a power transmitting means interposed between a rotating shaft of the motor and the rotor and transmitting a rotational torque to the rotor, and an absorbing means for absorbing a reaction force corresponding to a sliding surface pressure higher than the preload acting on the sliding surface.

[0008] According to the present invention, when the rotating shaft of the motor is rotated in one direction, the rotational torque is transmitted to the rotor via the power transmission means, and the rotor slides and rotates on the sliding surface of the stator. That is, a high sliding surface pressure is applied to the sliding surface, and airtightness is maintained between the passages, so that a high-pressure side passage that flows out high-pressure working gas compressed by the compressor to a component of the refrigerator such as a pulse tube from the first passage through the second passage, and a low-pressure side passage that allows low-pressure working gas whose pressure has been reduced by expansion in the component to be recovered from the second passage through an internal passage of the valve housing to the compressor, is periodically switched. At this time, the stator is fixed within the valve housing (that is, for example, if the stator is fixed to the valve housing with fastening bolts, the sliding surface pressure that the sliding surface of the stator applies to the rotor can be constantly stabilized by the fastening bolts, even if a force caused by high-pressure working gas acts on the sliding surface of the stator from below), and an absorption means is provided to absorb the thrust reaction force acting on the rotor as the rotor rotates, and a configuration is adopted in which this is not transmitted to the rotating shaft of the motor.This makes it possible to stabilize the sliding surface pressure, which is determined as an appropriate value based on the relationship between the leak rate of the working gas and the amount of wear of the rotor, i.e., a sliding surface pressure higher than the preload, without causing motor failure or shortening of life.

[0009] In the present invention, the rotor is preferably made of a material having a lower rigidity than the stator, so that when the rotor wears preferentially and the surface pressure acting on the sliding surface of the stator becomes unstable, it is sufficient to replace only the rotor.

[0010] In the present invention, the direction from the stator to the rotor is defined as the up direction, the rotor has a cylinder head that is pressurized into a recess provided in the upper part of the rotor and is acted upon by a high-pressure working gas, and the shaft of the cylinder head is supported by a bearing provided in the valve housing, and the bearing constitutes the absorbing means. Furthermore, the power transmission means may include a support body that is connected to the rotating shaft and is elongated in a direction perpendicular to the up-down direction, and a plurality of pin members suspended from the support body, and each pin member is connected to the rotor. Furthermore, the preload applying means may be, for example, a coil spring that is compressed between the support body and the rotor. By adopting these configurations, the absorbing means, the power transmission means, and the preload applying means can be attached or removed in sequence from one direction without any special hand tools when assembling or disassembling the rotary valve, which is advantageous.

[0011] However, when the rotor slides and rotates in one direction on the sliding surface of the stator, uneven wear occurs on the contact surface of the rotor for some reason, and if this causes the central axis of the rotor to tilt with respect to the rotation shaft of the motor, it indicates that there is an unevenness in the surface pressure applied to the sliding surface, that is, that the surface pressure is not stabilized, and there is a risk of a load being applied to the rotation shaft of the motor. Here, in the above configuration, since the movement is restricted on a plane, one degree of freedom has already been reduced, and if it is not allowed to deviate from the plane (not to move from the center of rotation), two degrees of freedom must be reduced. Therefore, the above power transmission means may be configured to allow three to five degrees of freedom when connected to the rotor. And, in the case where the power transmission means is configured to include a support body and pin members and the pin members are connected to the rotor, a configuration can be adopted in which through holes are formed in the support body into which the upper ends of the pin members are loosely inserted, and each pin member is detachably attached to the support body while being inserted through the through holes. This is advantageous in that it allows the support of each pin member to move in the longitudinal direction, thereby preventing load from being applied to the rotating shaft of the motor. Note that if the through hole is configured as a long hole that is long in one direction, one degree of freedom will be added, but in reality, it is sufficient that the long hole is within the allowable range for the center of rotation to shift. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic cross-sectional view showing a configuration of a refrigerator to which a rotary valve for a refrigerator according to an embodiment of the present invention is applied. [Diagram 2] 5A and 5B are schematic cross-sectional views showing a state in which a passage through which the working gas flows in the rotary valve of the present embodiment is switched. [Diagram 3] FIG. 2 is an exploded perspective view of a main part of the rotary valve. [Figure 4] FIG. 11 is a schematic cross-sectional view showing a modified example of a rotary valve for a refrigerator. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, with reference to the drawings, an embodiment of a rotary valve for a refrigerator of the present invention will be described, in which the refrigerator is a single-stage pulse-tube refrigerator and a pressure-oscillated working gas is circulated through the pulse tube of the pulse-tube refrigerator.

[0014] 1, the pulse tube refrigerator Pr equipped with the rotary valve RV1 of this embodiment includes a pressure vibration generating means 1 which generates pressure vibration in a working gas such as helium gas, a pulse tube 2 into which the pressure-vibrated working gas flows, and a regenerator 3 which is provided between the pressure vibration generating means 1 and the pulse tube 2 and pre-cools the working gas flowing into the pulse tube 2, and the low temperature end 2a of the pulse tube 2 and the low temperature end 3a of the regenerator 3 are connected via a cooling stage 4 having a gas passage 41. Note that since the pulse tube 2, the regenerator 3, and the cooling stage 4 are publicly known components, further explanation will be omitted.

[0015] The pressure vibration generating means 1 includes a compressor 11 that compresses a working gas. A high-pressure gas line 51 through which a working gas compressed to a high pressure flows is connected to the compressor 11, and the high-pressure gas line 51 is branched, and the branched high-pressure gas lines 51a and 51b are connected to the high-temperature ends 2b and 3b of the pulse tube 2 and the regenerator 3 through the first and second valves V1 and V2, respectively. A low-pressure gas line 52 through which a low-pressure working gas whose pressure has been reduced by expansion flows is also connected to the compressor 11, and the low-pressure gas line 52 is branched, and the branched low-pressure gas lines 52a and 52b are connected to the high-temperature ends 2b and 3b of the pulse tube 2 and the regenerator 3 through the third and fourth valves V3 and V4, respectively. As a result, when the first and second valves V1 and V2 are opened and the third and fourth valves V3 and V4 are closed, a high-pressure side passage is formed through which high-pressure working gas is supplied from the compressor 11 to the pulse tube 2 and the regenerator 3, while when the first and second valves V1 and V2 are closed and the third and fourth valves V3 and V4 are opened, a low-pressure side passage is formed through which low-pressure working gas is recovered to the gas recovery side (low-pressure side) of the compressor 11. Then, the phase of the pressure oscillation of the working gas is controlled to generate cold at the low-temperature end 2a of the pulse tube 2 due to the expansion of the working gas. In this case, although not particularly shown or described, a buffer tank may be provided to control the phase of the pressure oscillation of the working gas. The rotary valve RV1 of this embodiment is used to realize such switching operations of the first to fourth valves V1 to V4 with a single part.

[0016] 2 and 3, the rotary valve RV1 of this embodiment includes a valve housing 6, a stator 7 fixed to the valve housing 6, a rotor 8 disposed opposite the stator 7, and a motor Mt that slides and rotates the rotor 8 around a central axis Cl passing through a sliding surface 7a of the stator 7 opposite the rotor 8. In the following, terms indicating directions such as up and down are based on the position in FIG. 2. The valve housing 6 made of a metal such as stainless steel includes a lower housing 61 having a recessed storage section on the upper surface in which the stator 7 is stored, and an upper housing 62 in which an accommodation space 62a is formed inside to accommodate components such as the rotor 8 when the upper housing 62 is attached to the lower housing 61. An opening 62b is provided in a side wall of the upper housing 62, which communicates with the low-pressure gas line 52 from the accommodation space 62a, and the accommodation space 62a becomes a low-pressure region through which a low-pressure working gas flows. In this case, the accommodation space 62a forms an internal passage of the valve housing 6. A stator 7 is press-fitted into the storage portion via a seal material Sm1 such as an O-ring, and an upper surface 7a of the stator 7 becomes a sliding surface for a rotor 8, which will be described later.

[0017] The stator 7 has a generally cylindrical contour and is made of a relatively rigid metal such as stainless steel. It is fixed to the lower housing 61 by the fastening bolt Bt1. As a result, even if a force caused by high-pressure working gas acts on the sliding surface 7a of the stator 7 from below, the fastening bolt Bt1 prevents the stator 7 from moving up and down, and the sliding surface pressure applied by the sliding surface 7a of the stator 7 to the rotor 8 can be constantly stabilized. The stator 7 is also provided with a first passage L11 (through which the high-pressure working gas compressed by the compressor 11 flows) connected to the first valve V1 or the second valve V2 and communicating with the high-pressure gas line 51, two second passages L21, L22, and two small passages L23, L24, each of which is located on the central axis Cl and reaches the sliding surface 7a of the stator 7. 3, the opening ends L21a, L22a of the second passages L21, L22 facing the sliding surface 7a are formed on both sides of the opening end L11a of the first passage L11 facing the sliding surface 7a at an interval in the sliding rotation direction of the rotor 8. The opening ends L23a, L24a of the small passages L23, L24 facing the sliding surface 7a have a smaller area than the opening ends L21a, L22a, and are provided adjacent to the opening ends L21a, L22a forward in the sliding rotation direction of the rotor 7, and play a role in generating pressure vibrations in the working gas.

[0018] The rotor 8 is composed of a cylindrical base 81 and a sliding part 82 formed on the lower surface of the base 81 and having a smaller diameter than the base 81. The sliding part 82 has an outline in which mutually symmetrical fan-shaped areas are cut out from the outer periphery of a cylindrical member, and the lower surface of the sliding part 82 becomes the contact surface (pressure receiving surface on which a reaction force acts) 8a that contacts the sliding surface of the stator 7. In this case, when the fan-shaped cutout parts of the sliding part 82 are located on the opening ends L21a, L22a and L23a, L24a, each of the second passages L21, L22 is in communication with the low pressure gas line 52 via the accommodation space 62a in the valve housing 6 (see FIG. 2(b)). The rotor 8 is made of a resin having a relatively lower rigidity than the stator 7, and an example of the resin used here is a fluororesin such as BEAREE (registered trademark). In addition, when comparing the rotor and the stator, the rotor side can be made of a material having a lower Young's modulus. In this way, if the rotor 8 and the stator 7 are made of different materials, the rotor 8 wears preferentially, and when the surface pressure acting on the sliding surface 7a of the stator 7 becomes unstable, it is necessary to replace only the rotor 8. The rotor 8 also has a third passage L3 that penetrates in the vertical direction and always communicates with the first passage L11, and two fourth passages L41, L42 that are spaced apart in the sliding rotation direction of the rotor 8 and have opening ends L41a, L42a that selectively match the opening ends L21a, L22a or the opening ends L21a, L23a and the opening ends L22a, L24a when the rotor 8 is slidably rotated from a state in which the second passages L21, L22 communicate with the accommodation space 62a in the valve housing 6.

[0019] A recessed hole is provided on the upper surface of the base 81 of the rotor 8 as a storage section 81a, and the cylinder head 83 is press-fitted into the storage section 81a via an O-ring Or1 with a degree of freedom of movement in the central axis direction (thrust direction). When high-pressure working gas acts from the first passage L11 and the third passage L3, a communication space 84 is defined in the space inside the storage section 81a located below the cylinder head 83. In this case, the area of ​​the lower surface of the cylinder head 83 is appropriately designed to provide a gap d of a size that does not cause pressure loss when the high-pressure gas flows. A cylindrical shaft section 83b having a groove 83a into which a support body described later fits is integrally formed on the cylinder head 83, and the shaft section 83b is supported by a bearing Br provided in the storage space 62a of the upper housing 62, and the bearing Br constitutes the absorbing means of this embodiment. The bearing Br is provided in a step portion formed on the inner surface of the upper wall of the upper housing 62, but is not limited thereto. In addition, since the pressure difference between the high pressure gas line 51 and the low pressure gas line 52 acts on the area of ​​the lower surface of the cylinder head 83, the force received by the cylinder head 83 due to the pressure difference becomes a sliding surface pressure higher than the preload on the sliding surface. In other words, the internal pressure of the communication space 84 substantially defined by the cylinder head 83 and the rotor 8 becomes a sliding surface pressure higher than the preload on the sliding surface, and the following configuration is used to suppress fluctuations in the sliding surface pressure. That is, the reaction force received by the cylinder head 83 (a reaction force corresponding to the sliding surface pressure) is transmitted to the bearing Br supported by the cylinder head 83, and is transmitted in order to the upper housing 62, the lower housing 61, and the stator 7, which are connected including a fastening bolt (not shown), and is counterbalanced at the sliding surface between the rotor 8 and the stator 7. In this way, the configuration has the feature of eliminating the influence of other components when generating a sliding surface pressure higher than the preload. At this time, the motor Mt is not included in the force transmission path, and is therefore not affected by the sliding surface pressure that is higher than the preload. Furthermore, two pin members 93 are arranged so that the rotational torque does not affect the sliding surface pressure, thereby reducing fluctuations caused by the moment.

[0020] The support 9 is composed of a rectangular columnar portion 91 extending in the thrust direction and a plate-shaped portion 92 extending at the lower end of the rectangular columnar portion 91 in a direction perpendicular to the thrust direction (left-right direction in FIG. 2(b)). Two pin members 93 are suspended from both longitudinal ends of the plate-shaped portion 92. In this case, the plate-shaped portion 92 is formed with a long hole (through hole) 92a along its longitudinal direction. The upper portion of each pin member 93 is loosely inserted into each long hole 92a, and an E-shaped retaining ring (E-ring) Er is attached to a groove 93a formed in the upper end portion of each pin member 93 protruding upward from each long hole 92a, thereby suspending each pin member 93. In this case, parts such as the support 9 and each pin member 93 constitute the power transmission means of this embodiment. The lower end of each pin member 93 is engaged with a pin hole 85 formed on the upper surface of the rotor 8 via an O-ring or the like. On the other hand, a square hole 91a is formed in the square column part 91, into which the rotating shaft Ar of the motor Mt provided on the upper surface of the upper housing 62 is inserted with a gap. The rotating shaft Ar has a square column shape following the square hole 91a.

[0021] The upper housing 62 is provided with a cover body 63 so as to surround the motor Mt. The cover body 63 is fixed to the upper housing 62 with a fastening bolt Bt2, and a seal member Sm2 such as an O-ring is provided on the underside of the cover body 63. The motor Mt is attached to the internal space 63a of the cover body 63, which communicates with the accommodation space 62a as a low-pressure area. The rotating shaft Ar of the motor Mt located on the central axis Cl protrudes into the accommodation space 62a through a through hole 62c provided in the upper housing 62, and the rotating shaft Ar is inserted through an O-ring Or2. As a result, the rotating shaft Ar has a rectangular column shape following the rectangular hole 91a, and the two shafts are in two-line or three-point contact with each other on the inner surface of the rectangular hole 91a, making it possible to transmit torque. Therefore, the support 9 rotates together with the rotating shaft Ar, and due to the presence of a gap at this time, even if the support 9 tilts for some reason, no load is applied to the rotating shaft Ar. The O-ring Or2 in the gap is disposed so as to apply a normal force to the contact surface, so that the rotating shaft Ar and the support 9 are connected by the static friction force of the O-ring Or2. A coil spring Cs fitted onto a pin member 93 is compressed between the support 9 and the rotor 8, and a predetermined preload (surface pressure) is applied to the sliding surface 7a of the stator 7 by the biasing force of the coil spring Cs, and the coil spring Cs constitutes the preload application means of this embodiment.

[0022] According to the above, the rotary valve RV1 shown in Fig. 2(a) is in a starting state, and in this starting state, the opening ends L41a, L42a of the sliding portion 82 of the rotor 8 vertically match the opening ends L21a, L23a and the opening ends L22a, L24a of the sliding surface 7a of the stator 7. That is, the first and second valves V1, V2 in Fig. 1 are open, and the third and fourth valves V3, V4 are closed, forming a high-pressure gas passage, and the high-pressure working gas compressed by the compressor 11 and flowing into the first passage L11 is supplied to the pulse tube 2 and the regenerator 3 through the high-pressure gas lines 51a, 51b. When the rotating shaft Ar of the motor Mt is rotated in one direction from this state, the rotational torque is transmitted to the rotor 8 through the support 9 and the pin members 93, and the rotor 8 slides and rotates in one direction on the sliding surface 7a of the stator 7. At this time, the opening ends L21a, L23a and the opening ends L22a, L24a of the sliding surface 7a of the stator 7 are successively closed by the contact surface 8a of the sliding portion 82 not having the opening ends L41a, L42a, and then the second passages L21, L22 communicate with the accommodation space 62a in the valve housing 6 through the portion of the stator 7 not having the sliding surface 7a (the portion cut out in a sector shape), and are completely opened at the position where the rotor 8 has slidably rotated by a predetermined rotation angle, as shown in Fig. 2(b). That is, the first and second valves V1, V2 in Fig. 1 are closed, and the third and fourth valves V3, V4 are opened, forming a low-pressure passage, and the low-pressure working gas whose pressure has been reduced by expansion is recovered to the gas recovery side of the compressor 11 through the low-pressure gas lines 52a, 52b.

[0023] When the rotor 8 is further rotated in one direction, the opening ends L41a and L42a of the sliding portion 82 first match with the opening ends L23a and L24a on the sliding surface 7a of the stator 7, the second valve V2 in FIG. 1 is opened, and the first, third and fourth valves V1, V3 and V4 are closed, and the high-pressure working gas is first supplied to the pulse tube 2 through the high-pressure gas line 51b. Next, the opening ends L41a and L42a of the sliding portion 82 also match with the opening ends L21a and L22a on the sliding surface 7a of the stator 7, and the high-pressure working gas is also supplied to the regenerator 3 through the high-pressure gas line 51a (the high-pressure side passage is completely formed). These operations are repeated, and the high-pressure side passage and the low-pressure side passage are periodically switched while generating pressure vibrations in the working gas. In addition, as long as high temperature and low temperature areas are steadily formed by the traveling waves accompanying the pressure vibrations, the sliding rotation direction of the rotor 8 shown in Figure 3 and the shapes of the opening ends L41a, L42a, and the opening ends L21a, L22a, L23a, and L24a are not limited to those described above.

[0024] Thus, according to this embodiment, the stator 7 is fixed in the valve housing 6 with the fastening bolts Bt1, and a configuration is adopted in which the bearing Br is provided to absorb the reaction force in the thrust direction acting on the rotor 8 as it slides and rotates, and the reaction force is not transmitted to the rotating shaft Ar of the motor Mt, thereby making it possible to stabilize the surface pressure, which is determined as an appropriate value based on the relationship between the leak rate of the working gas and the amount of wear of the rotor 8, and further, to prevent breakdown or shortening of the life of the motor Mt. In addition, the stabilization of the surface pressure makes it possible to make the average surface pressure value gradually approach the required leak rate (i.e., the average surface pressure value can be reduced compared to the conventional configuration), thereby making it possible to achieve a configuration in which the amount of wear of the rotor 8 is reduced (the life is improved). In addition, by using the E-ring Er to lock the support 9 and the pin member 93, and using the O-ring Or1 to lock the pin member 93 and the rotor 8, the bearing Br, support 9, pin member 93, and coil spring Cs can be attached or detached in order from one direction when assembling or disassembling the rotary valve RV1 without using any special hand tools such as a screwdriver, which is advantageous.

[0025] Here, when the rotor 8 slides and rotates in one direction on the sliding surface 7a of the stator 7, uneven wear occurs on the contact surface 8a of the rotor 8 for some reason, and if this causes the central axis of the rotor 8 to tilt with respect to the rotation axis Ar of the motor Mt, there is a risk of a load being applied to the rotation axis Ar of the motor Mt. In contrast, in this embodiment, through holes 92a into which the upper ends of the pin members 93 are loosely inserted are formed in the support 9, and the pin members 93 are detachably attached to the support 9 while being inserted through the through holes 92a. This allows the pin members 93 to move in the longitudinal direction of the support 9, which is advantageous in that it is possible to avoid a load being applied to the rotation axis Ar of the motor Mt. Note that the power transmission means has been described using an example having a longitudinal support 9 and a plurality of pin members 93 suspended from the support 9, but since the operation is restricted on a plane, one degree of freedom has already been reduced, and if it is not allowed to deviate from the plane (not to move from the center of rotation), two degrees of freedom must be reduced. Therefore, the power transmission means may have a configuration that allows three to five degrees of freedom when connected to the rotor 8. Furthermore, if the through hole 92a is configured as a long hole that is long in one direction, one degree of freedom will be added, but in reality, it is sufficient that the long hole is within an acceptable range that allows the center of rotation to shift.

[0026] Although the embodiment of the present invention has been described above, various modifications are possible without departing from the scope of the technical concept of the present invention. In the above embodiment, the rotary valve RV1 applied to the pulse tube refrigerator Pr has been described as an example, but the present invention is not limited to this, and can be applied to other refrigerators such as GM refrigerators. In the above embodiment, the coil spring Cs is used as the preload applying means, but the present invention is not limited to this. For example, referring to FIG. 4 in which the same elements or members are given the same reference numerals, in the rotary valve RV2 according to the modified example, a diaphragm Dp fastened by a mounting nut 95 is used instead of the coil spring Cs. A metal plate material Pm is disposed in close contact with the upper surface of the diaphragm Dp. A rectangular columnar body 96 corresponding to the rectangular columnar portion 91 of the above embodiment is attached to the center of the upper surface of the plate material Pm. In this way, the preload applying means may be configured such that the elastic deformation caused by the assembled state of FIG. 2 or FIG. 4 becomes the preload. By utilizing the elastic deformation, a stable preload can be applied to the sliding surface regardless of the attitude (gravitational acceleration direction) of the rotary valve. In addition, the sliding surface pressure higher than the preload in this modified example is brought about by the internal pressure of the communicating space 84 substantially defined by the diaphragm Dp and the rotor 8, and the area of ​​the lower surface of the cylinder head 83, which is the area subjected to the differential pressure, corresponds at least to the area of ​​the metal plate material Pm on the upper surface of the diaphragm Dp, which results in a sliding surface pressure higher than the preload.

[0027] Three plunger-type ball rollers 97 are provided around the prismatic body 96 at equal intervals on the upper surface of the plate material Pm, and a ball 97a provided at the upper end of the ball roller 97 for rolling is brought into contact with the inner surface of the upper wall of the upper housing 62. This makes it possible to absorb the thrust reaction force acting on the rotor 8 as the absorbing means of this modified example. In this case, the prismatic body 96 is formed with a square hole 96a into which the rotating shaft Ar is inserted with a gap therebetween, and each of the prismatic bodies 96 is engaged with the rotating shaft Ar, and the rotational torque of the rotating shaft Ar of the motor Mt is transmitted to the rotor 8 through the shear stress of the pin 98. The pin 98 can be made of a split pin or wire, and can be attached and detached without using hand tools during assembly and disassembly. Instead of the pin 98, the rotating shaft Ar can be made into a square column shape and engaged with an O-ring as in the above embodiment. Furthermore, as in the above modified example, when a single diaphragm Dp is used, a moment is generated when a force is applied to a position shifted from the center of the lower surface (pressing surface), so it is also possible to arrange multiple diaphragms (for example, three at 120° intervals) at equal intervals in the circumferential direction about the rotation axis of the rotation shaft Ar, so that the sum of the moments acting on the pressing surfaces of each diaphragm is set to zero. Preferably, the diaphragms are arranged as far away from the rotation axis as possible. By configuring in this way, it is possible to maintain uniformity in the surface pressure applied to the sliding surface and at the same time prevent the progression of uneven wear.

[0028] In the above embodiment, each pin member 93 is loosely inserted into the long hole 92a to allow the movement of each pin member 93 and therefore the support 9 of the rotor 8 in the longitudinal direction, but this is not limited to the above as long as the degree of freedom is allowed to be 3 to 5. For example, the support 9 and the rotor 8 can be connected by a flexible joint. In this case, the movement of the support 9 of the rotor 8 in the longitudinal direction is also allowed, so that it is possible to avoid a load being applied to the rotation shaft Ar of the motor Mt. As the flexible joint, a known one such as a constant velocity joint or an Oldham coupling can be used, so further explanation is omitted. Note that when the number of degrees of freedom is set to 4 or 5, which is 3 or more, it is preferable to provide a regulating element for the increased degrees of freedom. In the above embodiment, the distance obtained by subtracting the dimension of the loosely inserted portion of the upper part of the pin member 93 from the longitudinal dimension of the long hole 92a is a typical example of this regulating element. This regulating element is provided, for example, so that airtightness of the sliding surface, i.e., airtightness between each passage is maintained, and the fluctuation of the sliding surface pressure caused by the internal pressure similar to that of the communication space 84 is kept to 1% or less. By configuring in this way, a stable sliding surface pressure is maintained.

[0029] In addition, for example, if a clearance fit as specified in "JIS B 0401-1:2016" is applied to the storage portion 81a between the cylinder head 83 and the rotor 8, the free movement of the rotor 8 can be substantially limited to two degrees of freedom, namely, the rotation of the axis of rotation of the rotation shaft Ar and the axial direction, and the sliding surface pressure can be prevented from becoming uneven and the surface pressure can be stabilized. In the case of a modified example using the diaphragm Dp, a linear guide that has the same effect as the configuration of the cylinder head 83 and the rotor 8 may be added. In this way, when the degree of freedom of the rotor 8 is limited, the degree of freedom of the power transmission means is limited even if it has four or more degrees of freedom. In other words, there is no need to provide a regulating element for the increased degree of freedom. [Explanation of symbols]

[0030] RV1, RV2...rotary valve, Pr...pulse tube refrigerator (refrigerator), 6...valve housing, 62a...accommodation space (internal passage), 7...stator, 8...rotor, 81a...storage section (recess), 83...cylinder head, 83b...shaft, Mt...motor, L1...first passage, L21, L22...second passage, L3...third passage, L4...fourth passage, Br...bearing (absorbing means), 9...support (power transmission means), 92a...long hole (through hole), 93...pin member (power transmission means), Cs...coil spring (preload application means).

Claims

1. a valve housing, a stator fixed within the valve housing, a rotor disposed within the valve housing facing the stator, and a motor that slides and rotates the rotor relative to the stator about a central axis that passes through a sliding surface of the stator with which the rotor abuts, the stator is fixed to the valve housing by fastening bolts so that the sliding surface pressure applied to the rotor by the sliding surface of the stator is stabilized even when a force caused by high pressure working gas acts from below on the sliding surface of the stator, and the stator is formed with a first passage located on the central axis through which high pressure gas flows, and a plurality of second passages extending along the central axis around the first passage, and the rotor is formed with a third passage communicating with the first passage, and a fourth passage selectively communicating with the second passage when the rotor is slidably rotated from a state in which the second passage communicates with an internal passage of the valve housing, 1. A rotary valve for a refrigerator, further comprising: preload applying means for applying a preload as a sliding surface pressure to the sliding surface; power transmitting means interposed between a rotating shaft of the motor and the rotor for transmitting rotational torque to the rotor; and absorbing means for absorbing a reaction force corresponding to a sliding surface pressure higher than the preload acting on the sliding surface.

2. 2. The rotary valve for a refrigerator according to claim 1, wherein the rotor is made of a material having a lower rigidity than the stator.

3. 3. A rotary valve for a refrigerator according to claim 1 or 2, characterized in that a direction from said stator to said rotor is defined as an upper direction, said rotor has a cylinder head which is press-fitted into a recess provided in an upper part of said rotor and on which high-pressure working gas acts, a shaft portion of the cylinder head is supported by a bearing provided in said valve housing, and said bearing constitutes said absorbing means.

4. 4. The rotary valve for a refrigerator according to claim 1, wherein the power transmission means comprises a support body elongated in a direction perpendicular to the up-down direction and connected to the rotating shaft, and a plurality of pin members suspended from the support body, wherein through holes are formed in the support body into which upper ends of the pin members are loosely inserted, and each pin member is detachably attached to the support body with the pin members inserted through the through holes, thereby connecting each pin member to the rotor.

5. 5. The rotary valve for a refrigerator according to claim 1, wherein the preload applying means is constituted by a coil spring that is compressed between the support body and the rotor.

Images