JP2011002161A - Expansion device for pulse tube refrigerator and pulse tube refrigerator using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem wherein when a pulse tube refrigerator is mounted to a device requiring ultralow temperature, the size of a heat release fin determined based on required performance of the pulse tube refrigerator becomes a problem because the heat release fin formed integrally with a heat release part becomes a limitation during mounting to an expansion device; thus, make the heat release fins detachable and prevent decline in cooling performance by minimizing reduction in the heat release amount caused by the detachable heat release fins.SOLUTION: The heat release part of the expansion device of the pulse tube refrigerator comprises a heat release part body and the pair of heat release fins opposing to each other across the heat release part body. A heat-conductive substance is applied to a contact face of the heat release part body with the heat release fins, and the pair of heat release fins are fixed to the heat release part body via a fastening member penetrated from one of the heat release fins through the outer face inner side of the heat release part body and reaching the other heat release fin.

Description

  The present invention relates to an expander for a pulse tube refrigerator.

The pulse tube refrigerator is mounted on a device that requires extremely low temperature, and is used as a cooling device that replaces liquid nitrogen or the like.
An expander of a pulse tube refrigerator is generally composed of a heat radiating unit, a regenerator, a low temperature end, and a pulse tube. The heat radiating section has a function of releasing the heat of the working gas generated by the operation of the pulse tube refrigerator to the outside of the expander. Therefore, the heat radiating portion is provided with comb-shaped heat radiating fins to increase the heat radiation amount. The radiating fin is integrally formed with the radiating portion by machining or the like to prevent a decrease in heat conduction efficiency.

  Usually, the expansion machine is attached to the apparatus via a flange or the like provided in the heat radiating section. The flange or the like may be formed integrally with the heat radiating portion, or may be configured as a separate part and fixed to the heat radiating portion with a bolt or the like.

  Patent Document 1 is known as a prior art in which heat radiating fins are integrally formed with a heat radiating portion. For example, FIG. 8 is a prior art expander.

JP-A-6-300376 (5th page, FIG. 1)

  When the pulse tube refrigerator is mounted on a device that requires extremely low temperature, the size of the heat radiation fin determined from the required performance of the pulse tube refrigerator becomes a problem. This is because the heat radiating fins are integrally formed with the heat radiating portion, so that the heat radiating fins become a constraint when the expander is attached to the apparatus.

  In addition, when a pulse tube refrigerator is mounted on a device, there may be a large difference in cooling performance at each location of the radiation fin due to the relationship between the radiation fin and the peripheral structure of the device. In such a case, there is a problem that the cooling performance is deteriorated due to the deviation of heat due to the place where the working fluid passes, and that the regenerator and the pulse tube are distorted by thermal stress.

  In view of the above-described problems, an expander for a pulse tube refrigerator that makes it possible to remove heat radiation fins and minimize a decrease in the amount of heat radiation caused by making the heat radiation fins removable to prevent deterioration in cooling performance is provided. For the purpose.

  The expander of the pulse tube refrigerator according to claim 1 of the present invention is an expander of a pulse tube refrigerator composed of a heat dissipator, a regenerator, a low temperature end, and a pulse tube, and the heat dissipator is The heat radiating portion main body and at least a pair of heat radiating fins facing each other across the heat radiating portion main body, and a contact surface between the heat radiating portion main body and the heat radiating fin is coated with a high heat conductive material, and the pair of heat radiating fins Is fixed to the heat radiating part main body by a fastening member that penetrates the outer surface of the heat radiating part main body from one radiating fin to the other radiating fin.

  Moreover, the expander of the pulse tube refrigerator which concerns on Claim 2 of this invention is an expander of the pulse tube refrigerator of Claim 1, Comprising: The said fastening member is the said thermal radiation part main body from one radiation fin. It is characterized by comprising a fixing bolt that penetrates the outer surface inside and the other radiating fin, and a nut that is screwed to the fixing bolt from the other radiating fin side.

  Moreover, the expander of the pulse tube refrigerator which concerns on Claim 3 of this invention is an expander of the pulse tube refrigerator of Claim 1, Comprising: The said fastening member is the said thermal radiation part main body from one radiation fin. A fixing bolt that reaches the inside of the outer surface and the other radiating fin, wherein the other radiating fin is provided with a screw portion to which the fixing bolt is screwed.

  Moreover, the expander of the pulse tube refrigerator which concerns on Claim 4 of this invention is an expander of the pulse tube refrigerator of Claim 1, Comprising: The said fastening member is both a radiation fin and the said thermal radiation part main body. It is characterized by comprising a fixing bolt having screw parts at both ends penetrating the inside of the outer surface and a pair of nuts screwed to the fixing bolt from both of the radiation fins.

  The expander of the pulse tube refrigerator according to claim 5 of the present invention is the expander of the pulse tube refrigerator according to claim 1 or 4, wherein a heat pipe is provided in the axial direction inside of the fixing bolt. It is characterized by providing.

  The expander of the pulse tube refrigerator according to claim 6 of the present invention is the expander of the pulse tube refrigerator according to any one of claims 2 to 5, wherein the heat dissipating part main body is A through hole of the fixing bolt is provided, and a gap formed by the through hole and the fixing bolt is filled with a high thermal conductivity material.

  Furthermore, the expander of the pulse tube refrigerator of Claim 7 is comprised by the expander of any one of Claim 1 thru | or 6, a compressor, and a phase control part, It is characterized by the above-mentioned. .

In the present invention, since the heat dissipating part is constituted by the heat dissipating part main body and the heat dissipating fins, the degree of freedom of attachment to the apparatus and the degree of freedom of design of the heat dissipating fins are greatly increased.
Furthermore, by providing a heat pipe inside the fastening member in the axial direction, the amount of heat released between the pair of heat dissipating fins is made uniform, preventing deterioration in cooling performance due to heat bias due to the place where the working gas passes, and the regenerator and pulse Strain due to thermal stress generated in the tube can be suppressed.

It is a schematic block diagram of a pulse tube refrigerator. It is a general-view figure of the expander of the pulse tube refrigerator which concerns on 1st Embodiment. It is an axial sectional view of fixing bolt 314 of heat radiating part 31A concerning the 1st actual form. It is a general-view figure of the expander of the state which removed the radiation fin of the pulse tube refrigerator which concerns on 2nd Embodiment. It is a modification which concerns on a 1st actual form, Comprising: It is an axial sectional view of the fixing bolt 314 of the heat radiating part 31A. It is another modification which concerns on a 1st actual form, Comprising: It is an axial sectional view of the fixing bolt 314 of the thermal radiation part 31A. It is a modification of the cross-sectional shape of a thermal radiation part main body. It is a prior art expander.

A first embodiment according to the present invention will be described.
First, the pulse tube refrigerator will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a pulse tube refrigerator.

As shown in FIG. 1, the pulse tube refrigerator 100 includes a compressor 10, a connecting tube 20, an expander 30, and a phase control unit 40.
The compressor 10 includes a piston 11 and a cylinder 12. Since the compressor 10 is not a main part of the present invention, a detailed description is omitted.

Specifically, the expander 30 includes a heat radiating unit 31, a regenerator 32, a low temperature end 33, and a pulse tube 34.
Specifically, the phase control unit 40 includes an inertance tube 41 and a buffer tank 42.

In such a pulse tube refrigerator 100, a flow path is formed. For example, helium is sealed as working gas (refrigerant gas) in the flow path.
Next, the operation principle of the pulse tube refrigerator 100 will be described. When the pulse tube refrigerator 100 is operated, the piston 11 reciprocates in the cylinder 12 of the compressor 10, whereby the working gas in the cylinder 12 is compressed and expanded. Such working gas reaches the connecting pipe 20, the heat radiating unit 31, the regenerator 32, the low temperature end 33, the pulse tube 34, the inertance tube 41, and the buffer tank 42 from the compressor 10. The working gas flows as a reciprocating flow in a series of systems between the compressor 10 and the phase controller 40.

  Here, the working gas flows in the inertance tube 41 and the buffer tank 42 of the phase control unit 40 with a pressure amplitude substantially sinusoidally, thereby causing a phase difference between the pressure change and the flow rate change. Can be generated. When these fluid circuits are compared with electric circuits, the inertance tube 41 corresponds to an inductance component and a resistance component, and the buffer tank 42 corresponds to a capacitance component. Such a phase control unit 40 can change the phase difference of the flow rate with respect to the pressure of the working gas from −90 ° to + 90 °.

  As described above, when the pulse tube refrigerator 100 is operated, a phase difference is generated between the pressure and the flow rate of the working gas in the pulse tube 34 due to the phase control effect by the pulse tube 34 and the phase control unit 40, and the pressure and flow rate. The work that is made becomes PV work at the low temperature end portion 33, and cold is generated at the low temperature end portion 33. This generated cold is called low-temperature PV work.

  Here, the low temperature end portion 33 is interposed between the regenerator 32 and the pulse tube 34 as described above. During operation of the pulse tube refrigerator 100, the working gas sent out in the compression process of the compressor 10 becomes a low temperature in the regenerator 32 and flows into the pulse tube 34, and adiabatically expands inside the pulse tube 34, thereby lowering the temperature. Heat is absorbed at the end 33, and the working gas flows out to the phase controller 40. Contrary to the above, in the process where the working gas passes from the phase control unit 40 through the pulse tube 34 and is refluxed to the low temperature end portion 33, heat is not generated or absorbed because it changes at a substantially constant volume. That is, there is no heat generation at the low temperature end portion 33, and only the heat absorption is performed, and cold is generated.

Next, the expander of the pulse tube refrigerator will be described in detail with reference to the drawings. FIG. 2 is an overview of the expander of the pulse tube refrigerator according to the first embodiment.
The expander 30 includes a heat radiating portion 31A, a regenerator 32, a low temperature end portion 33, and a pulse tube 34. Further, the heat radiating portion 31A includes a heat radiating portion main body 311A, a pair of heat radiating fins 312 and 313, and a fixing bolt 314. In FIG. 2, the heat dissipating fins 312 and 313 are indicated by a wire frame in order to make it easy to understand the relationship with the peripheral parts. FIG. 3 is a sectional view in the axial direction of the fixing bolt 314 of the heat dissipating part 31A.

The heat dissipating part main body 311A is formed in a rectangular parallelepiped, and is provided with four bolt holes for fixing bolts 314 penetrating a pair of opposed surfaces.
The pair of heat radiation fins 312 and 313 attached to the heat radiation portion main body 311A is provided with a bolt hole for the fixing bolt 314 in one heat radiation fin 312 and a female screw for the fixing bolt 314 in the other heat radiation fin 313. .

  The radiating fins 312 and 313 are arranged at positions facing each other across the radiating portion main body 311A, and the fixing bolt 314 is inserted from the bolt hole of one radiating fin 312 and screwed with the female screw of the other radiating fin 313, It is fixed to the heat dissipating part main body 311A by the axial force of the fixing bolt 314. That is, the fixing bolt 314 functions as a fastening member to the heat dissipating part main body 311A of the heat dissipating fins 312 and 313.

  Note that there is always a gap between the contact surfaces of the two parts. For example, it can be understood from the fact that there is roughness in the micrometer unit even if it is a flat surface. The gap becomes an air layer and reduces the heat conduction efficiency between the two parts. Therefore, in order to prevent a decrease in heat conduction efficiency between the two parts, it is important to fill the gap and eliminate the air layer. Therefore, in the embodiment of the present invention, although not shown, a high thermal conductive material such as thermal grease is applied to the contact surface between the heat radiating portion main body 311A and the heat radiating fins 312 and 313. A minute gap generated on the contact surface between the heat dissipating part main body 311A and the heat dissipating fins 312 and 313 is filled with a high thermal conductive material such as thermal grease to reduce the heat transfer efficiency between the heat dissipating part main body 311A and the heat dissipating fins 312 and 313. This is to prevent it.

  Furthermore, a high thermal conductive material such as thermal grease may be filled in a gap formed by the bolt hole and the fixing bolt 314 of the heat radiating unit main body 311A. This is because heat can be increased by transferring heat to the heat radiation fins 312 and 313 via the fixing bolt 314. In the first embodiment according to the present invention, the heat dissipating part 31A is composed of the heat dissipating part main body 311A, the heat dissipating fins 312 and the heat dissipating fins 313, whereby the expander 30 with the heat dissipating fins 312 and 313 removed is provided as a device. After the assembly, the assembly of the expander 30 to the device is completed by fixing the radiation fin 312 and the radiation fin 313 to the radiation unit body 311A again. Thereby, the assembly | attachment part of an apparatus and the expander 30 can be designed compactly. Furthermore, the degree of freedom in designing the heat radiation fins 312 and 313 is increased. Furthermore, it becomes possible to manufacture the radiation fins 312 and 313 with a drawing material or the like, and the manufacturing cost can be suppressed. Further, since the fixing bolt 314 passes through the inside of the heat radiating portion main body 311A, the heat radiating fins 312 and 313 are not warped by the axial force of the fixing bolt 314. Note that the size and the like of the radiation fins 312 and 313 can be arbitrarily determined and do not need to be the same size. For example, when the amount of heat radiation varies depending on the surrounding environment when assembled in the apparatus, the size of the radiation fins 312 and 313 may be different to cool the working gas uniformly.

Next, a second embodiment according to the present invention will be described with reference to the drawings. However, description of parts common to the first embodiment is omitted.
The expander 30 includes a heat radiating portion 31B, a regenerator 32, a low temperature end portion 33, and a pulse tube 34. FIG. 4 is a schematic view of the expander with the heat radiation fins 312 and 313 removed in the second embodiment according to the present invention. The heat radiating part 31B includes a heat radiating part main body 311B, a pair of heat radiating fins 312 and 313, and a fixing bolt 314. In FIG. 4, the radiating fins 312 and 313 are the same as the radiating fins of the first embodiment of FIG. 2, and the difference from the first embodiment resides in the radiating portion main body 311B. This is an overview of the expanded machine.

  The heat dissipating part main body 311B is formed in a rectangular parallelepiped, and is provided with four U-shaped grooves for the fixing bolts 314 penetrating a pair of opposed surfaces. The U-shaped groove is formed such that when the fixing bolt 314 is inserted, the entire head of the fixing bolt 314 is located on the inner side of the outer surface of the heat dissipating part main body 311B on the opening side of the U-shaped groove. .

  The pair of heat radiation fins 312 and 313 attached to the heat radiation part main body 311B is provided with a bolt hole for the fixing bolt 314 in one heat radiation fin 312 and a female screw for the fixing bolt 314 in the other heat radiation fin 313. .

  The radiating fins 312 and 313 are arranged at positions facing each other across the radiating portion main body 311B, and the fixing bolt 314 is inserted from the bolt hole of one radiating fin 312 and screwed with the female screw of the other radiating fin 313, It is fixed to the heat radiating portion main body 311B by the axial force of the fixing bolt 314.

Although not shown, a high thermal conductive material such as thermal grease is applied to the contact surface between the heat radiating portion main body 311B and the heat radiating fins 312 and 313.
The bolt holes for the fixing bolts 314 in the heat dissipating part main body 311A are U-shaped grooves in the heat dissipating part main body 311B, so that the heat dissipating fins 312 and the heat dissipating fins 313 are temporarily assembled with the two fixing bolts 314 to dissipate heat. It is possible to assemble the unit main body 311B. As a result, when assembling the heat dissipating fins 312 and 313 after the heat dissipating part with the heat dissipating fins 312 and 313 removed from the apparatus, the heat dissipating fins 312 and the heat dissipating fins 313 are separated from each other. Even if it is difficult to assemble the structure, it can be assembled if a sufficient space can be secured on the radiating fin 312 side and the opening side of one U-shaped groove of the radiating portion main body 311B.

  Modifications of the first and second embodiments according to the present invention will be described. FIG. 5 is a cross-sectional view in the axial direction of the fixing bolt 314 of the heat dissipating part 31A, showing a modification of the first embodiment. The female screw of the other heat dissipating fin 313 is used as a bolt hole, the heat dissipating fins 312 and 313 are arranged at positions facing each other across the heat dissipating part main body 311A or the heat dissipating part main body 311B, and the fixing bolt 314 is the bolt hole of one heat dissipating fin 312. Is inserted from the other radiating fin 313 side and screwed with a nut 315 and fixed to the radiating portion main body 311A or the radiating portion main body 311B by the axial force of the fixing bolt 314 generated by the fixing bolt 314 and the nut 315. good. That is, the fixing bolt 314 and the nut 315 can be used as a fastening member to the heat radiating portion main bodies 311A and 311B of the heat radiating fins 312 and 313. By using the fixing bolt 314 and the nut 315, the radiation fins 312 and 313 can be shared. Similar modifications can be made to the second embodiment.

  Furthermore, other modifications of the first and second embodiments according to the present invention will be described. FIG. 6 is a cross-sectional view in the axial direction of the fixing bolt 314A of the heat radiating part 31A, showing a modification of the first embodiment. The holes through which the fixing bolts of the radiating fins 312 and 313 pass are bolt holes, the fixing bolts 314A have screw portions at both ends, and the radiating fins 312 and 313 are opposed to each other across the radiating portion main body 311A or the radiating portion main body 311B. The fixing bolt 314A is inserted through the bolt holes of the radiation fins 312, 313, screwed with nuts 315 from both sides of the radiation fins 312, 313, and the fixing bolt 314A generated by the fixing bolt 314A and the nut 315 You may fix to the thermal radiation part main body 311A or the thermal radiation part main body 311B with an axial force. That is, fixing bolts 314A having screw portions at both ends and a pair of nuts 315 can be used as fastening members to the heat radiating portion main bodies 311A and 311B of the heat radiating fins 312 and 313. Similar modifications can be made to the second embodiment.

  Furthermore, as a modification of the first and second embodiments according to the present invention, the heat dissipating part main body 311A or the heat dissipating part main body 311B is not limited to a rectangular parallelepiped. What is necessary is just to have two opposing surfaces. Furthermore, the two opposing surfaces do not have to be flat surfaces, but may be curved surfaces. However, in such a case, the contact surfaces of the heat dissipating fins 312 and 313 with the heat dissipating part main body have the same shape as the contact surfaces of the heat dissipating part main bodies 311A and 311B. In FIG. 7, the modification of the cross-sectional shape of a thermal radiation part main body is shown. Moreover, a radiation fin is not limited to a pair, and can be attached to two or more opposing surfaces. If the cross section is rectangular, two pairs may be used, and if the cross section is hexagonal, three pairs may be used.

  Furthermore, although not shown, a heat pipe may be provided inside the fixing bolt 314. For example, when the amount of heat radiation varies depending on the surrounding environment of each heat radiation fin, heat is transferred from the heat radiation fin with a small heat radiation amount to the heat radiation fin with a large heat radiation amount by the heat pipe, depending on where the working gas passes. Therefore, it is cooled uniformly. Since the working gas is uniformly cooled, the flow of the working gas is stabilized, and deterioration of the cooling performance can be prevented. Furthermore, distortion due to thermal stress generated in the regenerator and the pulse tube can be suppressed.

  In addition, in the said description, what has a counterbore corresponding to the head of a bolt or a nut shall be contained with a bolt hole.

DESCRIPTION OF SYMBOLS 10 Compressor 20 Connection pipe 30 Expander 31 Heat radiation part 311 Heat radiation part main body 312,313 Heat radiation fin 314 Fixing bolt 32 Regenerator 33 Low temperature end part

Claims (7)

An expander of a pulse tube refrigerator composed of a heat radiating unit, a regenerator, a low temperature end and a pulse tube,
The heat dissipating part is composed of a heat dissipating part main body and at least a pair of heat dissipating fins facing each other across the heat dissipating part main body,
A high thermal conductivity material is applied to the contact surface between the heat dissipating part body and the heat dissipating fin,
The pair of heat radiating fins are fixed to the heat radiating unit main body by a fastening member that penetrates the outer surface of the heat radiating unit main body from one radiating fin to the other radiating fin,
An expander for a pulse tube refrigerator. It is an expander of the pulse tube refrigerator according to claim 1,
The fastening member is composed of a fixing bolt that penetrates from one radiating fin to the inside of the outer surface of the radiating portion main body and the other radiating fin, and a nut that is screwed to the fixing bolt from the other radiating fin side. ,
An expander for a pulse tube refrigerator. It is an expander of the pulse tube refrigerator according to claim 1,
The fastening member is a fixing bolt that reaches from one radiating fin to the inside of the outer surface of the radiating portion main body and the other radiating fin,
The other radiating fin is provided with a screw portion to which the fixing bolt is screwed,
An expander for a pulse tube refrigerator. It is an expander of the pulse tube refrigerator according to claim 1,
The fastening member is composed of both radiating fins and a fixing bolt having screw portions at both ends penetrating the inside of the outer surface of the radiating portion main body, and a pair of nuts screwed to the fixing bolt from both the radiating fin sides. That
An expander for a pulse tube refrigerator. The expander of the pulse tube refrigerator according to claim 1 or 4,
Providing a heat pipe inside the fastening member in the axial direction;
An expander for a pulse tube refrigerator. It is an expander of the pulse tube refrigerator according to any one of claims 2 to 5,
The heat dissipating part main body is provided with a through hole for the fixing bolt,
Filling the gap formed by the through hole and the fixing bolt with a high thermal conductivity material,
An expander for a pulse tube refrigerator.     The pulse tube refrigerator comprised by the expander of any one of Claims 1 thru | or 4, the compressor, and the phase control part.