Rotary valve structure and ultra-low temperature refrigerator

Abstract

The utility model discloses a subject is in reducing the drive torque of rotary valve of ultralow temperature refrigerator and reducing use cost. Rotary valve (24) have: casing (34);Valve main body (50) are installed in casing (34) with the mode that make with high pressure port (28) connection's high pressure area (36), with low pressure port (30) connection's 1st low pressure area (38) and via the intercommunication flow path (42) with 1st low pressure area (38) connection's 2nd low pressure area (40) form in casing (34);And valve disc (48), can rotate around rotary shaft (24a), along rotary shaft (24a) with valve main body (50) adjacent, and configure in 1st low pressure area (38). Valve main body (50) have along rotary shaft (24a) towards with valve disc (48) opposite one side's distal end side surface (58). 1st part (58a) in distal end side surface (58) faces high pressure area (36), and 2nd part (58b) in distal end side surface (58) faces 2nd low pressure area (40). The intercommunication flow path (42) is formed in casing (34).

Description

Technical Field

[0001] This utility model relates to a rotary valve structure for an ultra-low temperature refrigeration machine, and an ultra-low temperature refrigeration machine having the rotary valve structure. Background Technology

[0002] Typically, the rotary valve of a cryogenic refrigeration unit has a non-rotating valve seat and a valve disc that rotates relative to the valve seat. To prevent refrigerant gas from leaking from the sliding surface between the valve seat and the valve disc, there are known techniques that apply the pressure of the refrigerant gas to the valve seat to press the valve seat against the valve disc.

[0003] The stronger the force applied when pressing the valve seat against the valve disc, the greater the frictional force generated when the valve disc rotates relative to the valve seat. Consequently, the driving torque of the motor required to rotate the valve disc also increases. Furthermore, stronger pressing force leads to faster wear on the valve seat and valve disc, resulting in increased frequency of rotary valve replacement, repair, and maintenance, thus increasing the operating costs of the cryogenic refrigeration unit. Utility Model Content

[0004] One of the exemplary objectives of one embodiment of this utility model is to reduce the driving torque of the rotary valve of the cryogenic refrigerator and reduce the cost of use.

[0005] According to one embodiment of the present invention, a rotary valve structure for a cryogenic refrigerator is provided. The rotary valve structure includes: a housing; a valve body mounted on the housing to form a high-pressure region connected to the high-pressure side of the cryogenic refrigerator, a first low-pressure region connected to the low-pressure side of the cryogenic refrigerator, and a second low-pressure region connected to the first low-pressure region via a connecting flow path; and a valve disc rotatable about a rotation axis, adjacent to the valve body along the rotation axis, and disposed in the first low-pressure region. The valve body has a distal side surface facing the side opposite to the valve disc along the rotation axis. A first portion of the distal side surface faces the high-pressure region, and a second portion of the distal side surface faces the second low-pressure region. A connecting flow path is formed in the housing.

[0006] The connecting flow path may have a straight section extending from the first low-pressure region in a direction parallel to the rotation axis and an undercut section connecting the straight section to the second low-pressure region in a direction perpendicular to the rotation axis.

[0007] The diameter of the connecting flow path can be 2 mm or more. Furthermore, the diameter of the connecting flow path can also be less than 10 mm.

[0008] According to one embodiment of the present invention, an ultra-low temperature refrigeration machine having the above-described rotary valve structure is provided.

[0009] Utility Model Effect

[0010] According to this invention, the driving torque of the rotary valve in an ultra-low temperature refrigerator can be reduced and the operating cost can be lowered. Attached Figure Description

[0011] Figure 1 This is a schematic diagram illustrating the cryogenic refrigerator involved in the embodiment.

[0012] Figure 2 This is a schematic diagram illustrating the rotary valve of the cryogenic refrigerator involved in the embodiment.

[0013] Figure 3 This is a schematic diagram showing the rotary valve of the cryogenic refrigerator involved in the comparative example.

[0014] In the diagram: 10-Cryogenic refrigerator, 24-Rotary valve, 24a-Rotating shaft, 34-Housing, 36-High pressure zone, 38-First low pressure zone, 40-Second low pressure zone, 42-Connecting flow path, 42a-Straight section, 42b-Undercut section, 48-Valve disc, 50-Valve body, 58-Far-end side surface, 58a-Part 1, 58b-Part 2. Detailed Implementation

[0015] The embodiments of this utility model will now be described in detail with reference to the accompanying drawings. In the following description and drawings, identical or equivalent constituent elements, components, and processes are labeled with the same symbols, and repeated descriptions are omitted where appropriate. For ease of explanation, the proportions or shapes of the parts are appropriately set in the drawings, which are not intended to be limiting unless otherwise specified. The embodiments are illustrative and do not limit the scope of this utility model. All features or combinations thereof described in the embodiments are not necessarily the essence of the utility model.

[0016] Figure 1 This is a schematic diagram illustrating the cryogenic refrigerator 10 involved in the embodiment. Figure 2 This is a schematic diagram showing the rotary valve 24 of the cryogenic refrigerator 10 according to the embodiment.

[0017] like Figure 1 As shown, the cryogenic refrigerator 10 is a single-stage pulse tube refrigerator of the Gifford-McMahon (GM) type, which includes a compressor 12, a cold head 14 and a valve unit 16.

[0018] The compressor 12 is configured to recover refrigerant gas from the cryogenic refrigerator 10 from the cold head 14 via the valve unit 16, pressurize the recovered refrigerant gas, and then supply refrigerant gas back to the cold head 14 via the valve unit 16. The refrigerant gas, also known as the working gas, is usually helium, but other suitable gases can also be used.

[0019] Typically, the pressure of the refrigerant gas supplied from compressor 12 to cold head 14 and the pressure of the refrigerant gas recovered from cold head 14 to compressor 12 are both much higher than atmospheric pressure; these can be referred to as the first high pressure and the second high pressure, respectively. The second high pressure is lower than the first high pressure. For ease of explanation, the first high pressure and the second high pressure are also simply referred to as high pressure and low pressure, respectively. Typically, the high pressure can be, for example, 1.5–3.5 MPa. The low pressure can be, for example, 0.2–2.0 MPa.

[0020] The cold head 14 includes a cooling platform 18, a pulse tube 20, and a cold accumulator 22. The cooling platform 18 is the part that is cooled to an ultra-low temperature when the cryogenic refrigerator 10 is operating. An object to be cooled by the cryogenic refrigerator 10 is thermally connected to the cooling platform 18.

[0021] The pulse tube 20 is a hollow cylindrical tube, and the cold accumulator 22 is a cylindrical tube filled with cold storage material. The two are arranged adjacent to each other, with their central axes parallel. The low-temperature ends of the pulse tube 20 and the cold accumulator 22 are structurally and thermally connected via a cooling platform 18. Furthermore, the cooling platform 18 is configured to allow refrigerant gas to flow between the low-temperature ends of the pulse tube 20 and the cold accumulator 22. In other words, refrigerant gas can flow between the low-temperature ends of the pulse tube 20 and the cold accumulator 22 via the cooling platform 18.

[0022] Valve unit 16 includes a rotary valve 24 that functions as both a high-pressure valve V1 and a low-pressure valve V2. Specifically, the rotary valve 24 is configured to periodically switch the flow path between the high-pressure and low-pressure sides of the compressor 12 and the cold head 14 (i.e., the pulse tube 20 and the accumulator 22). The rotary valve 24 is configured to close the low-pressure valve V2 when the high-pressure valve V1 is open, and conversely, to close the high-pressure valve V1 when the low-pressure valve V2 is open.

[0023] Furthermore, the high-pressure side of the compressor 12 is connected to the high-pressure port 28 of the valve unit 16 via a high-pressure pipe 26a, and the low-pressure side of the compressor 12 is connected to the low-pressure port 30 of the valve unit 16 via a low-pressure pipe 26b. The gas inlet / outlet 32 ​​of the valve unit 16 is connected to the cold head 14 via inlet / outlet pipes 26c.

[0024] If the high-pressure valve V1 is opened, refrigerant gas is supplied from the high-pressure side of the compressor 12 to the cold head 14 through the high-pressure valve V1. On the other hand, if the low-pressure valve V2 is opened, refrigerant gas is recovered from the cold head 14 to the low-pressure side of the compressor 12 through the low-pressure valve V2. In this way, refrigerant gas can flow between the compressor 12 and the cold head 14 through the valve unit 16.

[0025] It is known that pulse tube refrigerators have a phase control mechanism to form a thermodynamic cycle for cryogenic cooling. The valve unit 16, either alone or together with a buffer tank (not shown) provided as needed, is configured to function as the phase control mechanism. As the phase control mechanism of the cryogenic refrigerator 10, various known structures can be appropriately adopted, such as bidirectional intake type, 4-valve type, active buffer type, or others, and therefore will not be described in detail here.

[0026] According to this structure, the cryogenic refrigerator 10 can generate PV work at the cryogenic end of the pulse tube 20 by appropriately delaying the phase of the displacement vibration of the gas component (also known as the gas piston) in the pulse tube 20 relative to the pressure vibration of the refrigerant gas generated by the valve unit 16, so as to cool the cooling stage 18.

[0027] like Figure 2 As shown, the valve unit 16 includes a housing 34 that houses the rotary valve 24. The housing 34 contains the aforementioned high-pressure port 28, low-pressure port 30, and gas inlet / outlet 32. Within the housing 34, a high-pressure region 36 connected to the high-pressure port 28, a first low-pressure region 38 connected to the low-pressure port 30, and a second low-pressure region 40 connected to the first low-pressure region 38 via a connecting flow path 42 are formed.

[0028] The rotary valve 24 includes a motor 44, a coupling 46, a valve disc 48, and a valve body 50. These components are arranged sequentially along the rotation axis 24a of the rotary valve 24.

[0029] The motor 44 can be mounted on the outside of the housing 34. The motor 44 can be an electric motor that rotates the rotary valve 24 about its rotation axis 24a.

[0030] Coupling 46 is coaxially configured with the rotating shaft 24a of rotary valve 24, and connects motor 44 to valve disc 48 so that the valve disc 48 is rotated by the rotation output of motor 44. For example, as Figure 2 As shown, coupling 46 can be fixed to the output shaft 44a of motor 44 on one side along the rotation shaft 24a of rotary valve 24, and connected to valve disc 48 on the other side via connecting pin 52. Alternatively, the output shaft 44a of motor 44 can be directly connected to valve disc 48, instead of connecting motor 44 to valve disc 48 via coupling 46.

[0031] The valve disc 48 is coaxially arranged with the rotating shaft 24a of the rotary valve 24, and is adjacent to the valve body 50 along the rotating shaft 24a on the side opposite to the coupling 46. The valve disc 48 and the coupling 46 are disposed together in the first low-pressure region 38. Furthermore, the valve disc 48 is supported by the bearing 54 so that it can rotate about the rotating shaft 24a relative to the housing 34. Therefore, when the motor 44 is driven and the coupling 46 rotates, the valve disc 48 rotates together with the output shaft 44a of the motor 44 and the coupling 46 about the rotating shaft 24a.

[0032] Furthermore, the valve disc 48 has a high-pressure recess 48a and a low-pressure recess 48b that form part of the flow path of the rotary valve 24. The high-pressure recess 48a is connected to the high-pressure region 36, and the low-pressure recess 48b is connected to the first low-pressure region 38. The high-pressure recess 48a and the low-pressure recess 48b are formed at different positions on the surface of the valve disc 48 that contacts the valve body 50.

[0033] The valve body 50 is mounted on the housing 34 in a manner that does not rotate relative to the housing 34 about the rotation axis 24a. For example... Figure 2 As shown, a recess for receiving the valve body 50 is formed in the housing 34, into which the valve body 50 can be embedded.

[0034] Additionally, the valve body 50 can be mounted on the housing 34 in a manner that allows for a certain degree of movement relative to the housing 34 along the axial direction of the rotation axis 24a. A spring 55 can be provided in the high-pressure region 36 to press the valve body 50 against the valve disc 48. By pressing the valve body 50 against the valve disc 48, the high-pressure recess 48a and the low-pressure recess 48b of the valve disc 48 seal against each other, thereby preventing refrigerant gas leakage between them.

[0035] The valve body 50 has: a proximal side surface 56 that contacts the valve disc 48, a distal side surface 58 that faces the side opposite to the valve disc 48 along the rotation axis 24a, and an outer peripheral surface 60 that connects the proximal side surface 56 and the distal side surface 58.

[0036] The valve body 50 is mounted on the housing 34 such that a high-pressure region 36, a first low-pressure region 38, and a second low-pressure region 40 are formed within the housing 34. The proximal surface 56 of the valve body 50 faces the first low-pressure region 38. Furthermore, a first portion 58a of the distal surface 58 of the valve body 50 faces the high-pressure region 36, and a second portion 58b of the distal surface 58 faces the second low-pressure region 40.

[0037] Depend on Figure 2 It can be seen that the first part 58a corresponds to the center of the distal side surface 58, and the second part 58b corresponds to the outer periphery of the distal side surface 58. Furthermore, the first part 58a and the second part 58b of the distal side surface 58 are at different heights in the direction along the rotation axis 24a, and the second part 58b is closer to the proximal side surface 56 than the first part 58a.

[0038] The first portion 58a of the distal side surface 58 faces the high-pressure region 36, while the proximal side surface 56 faces the first low-pressure region 38. Therefore, based on the pressure difference between the high-pressure region 36 and the first low-pressure region 38, a force is applied to the valve body 50 to press it against the valve disc 48. As described above, this pressing force helps prevent refrigerant gas leakage at the contact surface between the valve body 50 and the valve disc 48.

[0039] The stronger the force applied to press the valve body 50 against the valve disc 48, the greater the frictional force generated when the valve disc 48 rotates relative to the valve body 50. This increases the driving torque required for the motor 44 to rotate the valve disc 48, leading to a larger motor 44. Furthermore, greater frictional force promotes wear on both the valve body 50 and the valve disc 48, potentially increasing the frequency of replacement, repair, and other maintenance of the rotary valve. At least one of the valve body 50 and the valve disc 48 is made of a wear-resistant material, which is relatively expensive. Therefore, excessive pressure applied to the valve body 50 against the valve disc 48 could negatively increase the operating cost of the cryogenic refrigerator 10.

[0040] In this embodiment, the second portion 58b of the distal side surface 58 faces the second low-pressure region 40. Therefore, compared to the case where the entire surface of the distal side surface 58 faces the high-pressure region 36, the force required to press the valve body 50 against the valve disc 48 is reduced. Thus, the aforementioned adverse effects can be mitigated.

[0041] A first sealing member 62a, a second sealing member 62b, and a third sealing member 62c are installed on the outer peripheral surface 60 of the valve body 50. The first sealing member 62a is positioned on the outer peripheral surface 60 near the proximal side surface 56 to seal the first low-pressure region 38 and the gas inlet / outlet 32 ​​against each other. Therefore, leakage of refrigerant gas through the gap between the outer peripheral surface 60 and the housing 34 between the first low-pressure region 38 and the gas inlet / outlet 32 ​​is prevented by the first sealing member 62a. The second sealing member 62b is positioned on the outer peripheral surface 60 between the first sealing member 62a and the third sealing member 62c to seal the gas inlet / outlet 32 ​​and the second low-pressure region 40 against each other. The third sealing member 62c is positioned on the outer peripheral surface 60 near the distal side surface 58 to seal the second low-pressure region 40 and the high-pressure region 36 against each other.

[0042] The valve body 50 has a high-pressure flow path 50a and a bidirectional flow path 50b that form part of the flow path of the rotary valve 24. The high-pressure flow path 50a connects the high-pressure region 36 to the high-pressure recess 48a of the valve disc 48. The high-pressure flow path 50a extends from the first portion 58a of the distal side surface 58 of the valve body 50 to the proximal side surface 56. The bidirectional flow path 50b extends from the outer peripheral surface 60 of the valve body 50 to the proximal side surface 56. On the proximal side surface 56 of the valve body 50, the high-pressure flow path 50a is formed at the center, and the bidirectional flow path 50b is formed at a position further radially outward than the high-pressure flow path 50a.

[0043] As the valve disc 48 rotates while in contact with the valve body 50, the first state, in which the high-pressure recess 48a of the valve disc 48 is connected to the bidirectional flow path 50b of the valve body 50, and the second state, in which the low-pressure recess 48b of the valve disc 48 is connected to the bidirectional flow path 50b of the valve body 50, are periodically switched.

[0044] In the first state, the high-pressure port 28 is connected to the gas inlet / outlet 32 ​​via the high-pressure region 36, the high-pressure flow path 50a of the valve body 50, the high-pressure recess 48a of the valve disc 48, and the bidirectional flow path 50b of the valve body 50. That is, the first state is equivalent to... Figure 1 The diagram shows the state where the high-pressure valve V1 is open and the low-pressure valve V2 is closed.

[0045] Furthermore, in the second state, the gas inlet / outlet 32 ​​is connected to the low-pressure port 30 via the bidirectional flow path 50b of the valve body 50, the low-pressure recess 48b of the valve disc 48, and the first low-pressure region 38. That is, the second state is equivalent to... Figure 1 The diagram shows the state where low-pressure valve V2 is open and high-pressure valve V1 is closed. Additionally, Figure 2 This shows the second state of rotary valve 24.

[0046] Thus, the rotary valve 24 can alternately connect the high-pressure port 28 and the low-pressure port 30 to the gas inlet and outlet 32 ​​by rotating the valve disc 48 relative to the valve body 50.

[0047] A connecting flow path 42 connecting the first low-pressure region 38 to the second low-pressure region 40 is formed in the housing 34. Through the connecting flow path 42, the second low-pressure region 40 and the first low-pressure region 38 are pressure-equalized. To reduce the pressure difference that may occur between the first low-pressure region 38 and the second low-pressure region 40, and to rapidly equalize the pressure between the two regions, the diameter of the connecting flow path 42 is preferably sufficiently large, for example, it can be 2 mm or more or 3 mm or more. Furthermore, to avoid making the housing 34 forming the connecting flow path 42 too large, the diameter of the connecting flow path 42 can be, for example, 10 mm or less or 5 mm or less.

[0048] As an example, the connecting flow path 42 has: a straight portion 42a extending from the first low-pressure region 38 in a direction parallel to the rotation axis 24a, and an undercut portion 42b connecting the straight portion 42a to the second low-pressure region 40 in a direction perpendicular to the rotation axis 24a. To avoid interference with the gas inlet / outlet 32, the straight portion 42a is formed at a position different from the gas inlet / outlet 32 ​​in the circumferential direction centered on the rotation axis 24a. The diameter of the straight portion 42a can be within the aforementioned numerical range (e.g., 2 mm or more and 10 mm or less). The undercut portion 42b is formed in a recess in the housing 34 of the receiving valve body 50, extending the second low-pressure region 40 radially outward. The undercut portion 42b can be formed in the entire circumferential direction around the rotation axis 24a, or it can be formed only in a portion of the entire circumferential direction.

[0049] As an alternative, the connecting flow path 42 may extend obliquely relative to the rotation axis 24a to connect the first low-pressure region 38 to the second low-pressure region 40. In this case, the connecting flow path 42 may not have an undercut 42b.

[0050] In the illustrated example, only one connecting flow path 42 is provided. Alternatively, multiple connecting flow paths 42 may be formed in the housing 34. These connecting flow paths 42 may be formed at equal intervals in the circumferential direction, for example.

[0051] Figure 3 This diagram schematically illustrates the rotary valve structure of the cryogenic refrigerator involved in the comparative example. The rotary valve 24 includes a valve body 50 and a valve disc 48, and is housed in a housing 34. A connecting flow path 42 connects the first low-pressure region 38 to the second low-pressure region 40.

[0052] However, unlike the embodiments described above, the connecting flow path 42 is not formed in the housing 34, but rather in the valve body 50. The connecting flow path 42 extends from the proximal surface 56 to the distal surface 58 of the valve body 50. Therefore, in Figure 3 In the comparative examples shown, with Figure 2 Compared to the embodiment shown, the valve body 50 has a larger diameter.

[0053] The larger the diameter of the valve body 50, the larger the area of ​​the proximal side surface 56 and the distal side surface 58. As a result, the force by which the refrigerant gas presses the valve body 50 against the valve disc 48 may also increase. As mentioned above, this may lead to the adverse effects of increased motor drive torque and accelerated wear of the rotary valve 24.

[0054] In contrast, according to the embodiment, the connecting flow path 42 is formed in the housing 34. Therefore, compared to the comparative example, the increase in the size of the valve body 50 is suppressed, thereby reducing the force that presses the valve body 50 against the valve disc 48. This reduces the driving torque of the rotary valve 24 of the cryogenic refrigerator 10 and lowers the operating cost of the cryogenic refrigerator 10.

[0055] The present invention has been described above with reference to the embodiments. Those skilled in the art should understand that the present invention is not limited to the above-described embodiments, and various design changes and modifications are possible, and such modifications are also within the scope of the present invention. Various features described in one embodiment can also be applied to another embodiment. New embodiments resulting from combinations possess the effects of the combined embodiments.

[0056] The above embodiment uses a Gifford-McMahon (GM) pulse tube refrigerator as an example, but the cryogenic refrigerator 10 can be a GM refrigerator, a Solvay refrigerator, or other types of cryogenic refrigerators. The rotary valve structure described in this embodiment can be applied to such cryogenic refrigerators.

[0057] According to the embodiments, the present invention has been described using specific terms, but the embodiments only illustrate one aspect of the principle and application of the present invention. In the embodiments, multiple modifications and configuration changes are allowed without departing from the spirit of the present invention as specified in the technical solution.

Claims

1. A rotary valve structure for an ultra-low temperature refrigerator, characterized in that, have: case; The valve body is installed in the housing in such a way that it forms a high-pressure region connected to the high-pressure side of the cryogenic refrigerator, a first low-pressure region connected to the low-pressure side of the cryogenic refrigerator, and a second low-pressure region connected to the first low-pressure region via a connecting flow path. and A valve disc, which is rotatable about a rotation axis, is adjacent to the valve body along the rotation axis, and is disposed in the first low-pressure region; The valve body has a distal side surface along the rotation axis facing the side opposite to the valve disc, a first portion of the distal side surface facing the high-pressure region, and a second portion of the distal side surface facing the second low-pressure region. The connecting flow path is formed in the housing.

2. The rotary valve structure according to claim 1, characterized in that, The connecting flow path includes: a straight portion extending from the first low-pressure region in a direction parallel to the rotation axis, and an undercut portion connecting the straight portion to the second low-pressure region in a direction perpendicular to the rotation axis.

3. The rotary valve structure according to claim 1, characterized in that, The diameter of the connecting flow path is 2 mm or more.

4. The rotary valve structure according to claim 3, characterized in that, The diameter of the connecting flow path is less than 10 mm.

5. An ultra-low temperature refrigerator, characterized in that, It has the rotary valve structure according to any one of claims 1 to 4.

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