JP2011149600A - Pulse tube refrigerator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pulse tube refrigerator having a good straightening function between a cold storage tube and a pulse tube in comparison with a conventional one. <P>SOLUTION: In this pulse tube refrigerator in which a low-temperature end of the pulse tube and a low-temperature end of the cold storage tube are communicated by a communicating path, a low-temperature end side of the pulse tube of the communicating path is provided with a heat exchanger, the heat exchanger has a laminated body including at least first and second metal gauze, both of the first and second metal gauze are composed of copper or a copper alloy, interfaces of the metal gauze are diffusion-bonded to each other, and a side surface of the laminated body is diffusion-bonded to an internal wall configuring the communicating path. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a pulse tube refrigerator.

  2. Description of the Related Art A pulse tube refrigerator is used for cooling an apparatus that requires a cryogenic environment, such as a nuclear magnetic resonance diagnostic apparatus (MRI).

  In a pulse tube refrigerator, refrigerant gas (for example, helium gas), which is a working fluid compressed by a compressor, flows into the cold storage tube and the pulse tube, and the refrigerant gas is discharged from the pulse tube and the cold storage tube. By repeating the operation collected in the above, cold is formed at the low temperature ends of the regenerator tube and the pulse tube.

  The regenerator tube of the pulse tube refrigerator is composed of a cylindrical member (cylinder) having a regenerator material inside, and the pulse tube is composed of a hollow tubular member (cylinder). The low temperature ends of both cylinders communicate with each other through a communication path, and a cooling stage to which the object to be cooled is connected is installed at this position.

  In general, a heat exchanger is installed on the low temperature end side of the pulse tube, and this heat exchanger is formed of a laminated body made of a copper wire mesh or the like (Patent Document 1).

JP 2005-30704 A

  In a conventional pulse tube refrigerator, a low temperature end side of a pulse tube is filled with a laminate composed of a copper wire mesh or the like as a heat exchanger. The metal mesh is used in order to prevent a large difference in the velocity of the refrigerant gas when the refrigerant gas flows into the pulse tube from the cold storage tube, that is, to enhance the rectifying effect of the refrigerant gas.

  However, when a heat exchanger is configured by filling such a laminated body on the low-temperature end side of the pulse tube, the side surface of the laminated body and the inner wall of the groove that accommodates the laminated body are efficiently brought into thermal contact. It ’s difficult. For this reason, depending on the contact state between the two, the thermal resistance at the interface may change greatly, resulting in variations in heat exchange properties and a problem that the heat exchange performance of the pulse tube refrigerator may be reduced. .

  This invention is made | formed in view of such a background, and this invention aims at providing the pulse tube refrigerator which has a heat exchanger which exhibits favorable heat exchange property compared with the past. .

In the present invention, a pulse tube refrigerator in which the low temperature end of the pulse tube and the low temperature end of the regenerator tube are communicated by a communication path,
On the low temperature end side of the pulse tube of the communication path, a heat exchanger is installed,
The heat exchanger has a laminate including at least first and second wire meshes,
The first and second wire meshes are both made of copper or a copper alloy,
The interface between each wire mesh is diffusion bonded,
A pulse tube refrigerator characterized in that a side surface of the laminate is diffusion bonded to an inner wall constituting the communication path.

Further, in the present invention, a pulse tube refrigerator in which the low temperature end of the pulse tube and the low temperature end of the regenerator tube are communicated by a communication path,
On the low temperature end side of the pulse tube of the communication path, a heat exchanger is installed,
The heat exchanger includes a laminate including at least first and second wire meshes, and a housing.
The first and second wire meshes and the casing are both made of copper or a copper alloy,
The interface between each wire mesh is diffusion bonded,
The laminate is housed in the housing,
A pulse tube refrigerator is provided in which a side surface of the laminate is diffusion bonded to an inner wall of the casing.

In the above-described both pulse tube refrigerators, the laminate further includes a third wire mesh made of a metal different from copper or a copper alloy at the top,
The interface between each wire mesh is diffusion bonded,
The laminate may be disposed in the communication path so that the third wire mesh side is farthest from the low temperature end of the regenerator.

In this case, the laminated body further includes a fourth wire net made of a metal different from copper or a copper alloy,
The interface between each wire mesh is diffusion bonded,
The laminated body may be laminated in the order of the third wire mesh, the first wire mesh, the fourth wire mesh, and the second wire mesh.

Further, the laminate is configured by laminating six or more wire meshes,
The laminate is composed of an alternating repeating structure of a wire mesh made of a metal different from copper or a copper alloy and a wire mesh made of copper or a copper alloy throughout,
The interface between the metal meshes may be diffusion bonded.

  Moreover, in the pulse tube refrigerator according to the present invention, the mesh size of the wire mesh made of a metal different from the copper or copper alloy may be in the range of 0.02 mm to 0.58 mm.

  In the pulse tube refrigerator according to the present invention, the metal other than the copper or the copper alloy may be stainless steel or nickel.

  Moreover, in the pulse tube refrigerator according to the present invention, the mesh size of the wire mesh made of a metal different from each copper or copper alloy may be substantially equal.

  Moreover, in the pulse tube refrigerator according to the present invention, the mesh size of the wire mesh made of a metal different from each copper or copper alloy may be smaller than the mesh size of each copper or copper alloy wire mesh. .

  In the pulse tube refrigerator according to the present invention, the size of the mesh of the copper or copper alloy wire mesh may be in the range of 0.05 mm to 1.14 mm.

  In the pulse tube refrigerator according to the present invention, the mesh size of each copper or copper alloy wire mesh may be substantially equal.

  Alternatively, the size of each copper or copper alloy wire mesh may decrease continuously or stepwise from the wire mesh closest to the cold end of the regenerator tube toward the stacking direction of the laminate. .

  In the pulse tube refrigerator according to the present invention, the wire mesh may be rolled.

  According to the present invention, it is possible to provide a pulse tube refrigerator having a heat exchanger that exhibits better heat exchange than conventional ones.

It is the figure which showed roughly an example of the pulse tube refrigerator by this invention. It is a schematic sectional drawing of an example of a heat exchanger. It is a schematic exploded block diagram of the laminated body contained in a heat exchanger. It is a schematic sectional drawing of an example of another heat exchanger. It is a schematic exploded block diagram of another laminated body contained in a heat exchanger. It is a schematic exploded block diagram of another laminated body contained in a heat exchanger.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 schematically shows an example of a pulse tube refrigerator according to the present invention.

  As shown in FIG. 1, the pulse tube refrigerator 100 according to the present invention includes a compressor 110, a regenerator tube 120, a pulse tube 140, a cooling stage 180, and a buffer tank 190. The regenerative tube 120 has a high temperature end 125a and a low temperature end 125b, and the pulse tube 140 has a high temperature end 145a and a low temperature end 145b.

  An exhaust valve 110 a and an intake valve 110 b are connected to the compressor 110. The compressor 110 is connected to the high temperature end 125 a of the regenerator tube 120 via the gas flow path 112.

  The regenerator tube 120 is configured by a hollow cylinder 121, and the regenerator material 122 is filled therein. The cylinder 121 is made of, for example, stainless steel.

  The pulse tube 140 is constituted by a hollow cylinder 141 made of stainless steel, for example. A heat exchanger 149 a is provided on the high temperature end 145 a side of the pulse tube 140, and a heat exchanger 149 b is provided on the low temperature end 145 b side of the pulse tube 140.

  The low temperature end 125b of the regenerator tube 120 and the low temperature end 145b of the pulse tube 140 are in contact with and fixed to a cooling stage 180 made of copper. Further, the low temperature end 125 b of the regenerator tube 120 and the low temperature end 145 b of the pulse tube 140 are communicated with each other through a communication path 182 provided in the cooling stage 180. The cooling stage 180 is thermally connected to an object to be cooled (not shown), and the object to be cooled is cooled.

  The buffer tank 190 is connected to the high temperature end 145 a of the pulse tube 140 through the gas flow path 192 and the orifice 194.

  The regenerator tube 120 and the pulse tube 140 have their high temperature ends 125a and 145a connected to the flange 115, and are fixed thereby.

  Next, operation | movement of the pulse tube refrigerator comprised in this way is demonstrated easily.

  First, in a state where the exhaust valve 110a is opened and the intake valve 110b is closed, high-pressure refrigerant gas is supplied from the gas compressor 110 to the regenerator pipe 120 via the exhaust valve 110a and the gas flow path 112. The refrigerant gas that has flowed into the cold storage tube 120 passes through the communication path 182 from the low temperature end 125b of the cold storage tube 120 while being cooled by the cold storage material 122 to lower the temperature. The refrigerant gas is further cooled by a heat exchanger 149 b provided on the low temperature end 145 b side of the pulse tube 140 and flows into the pulse tube 140.

  At this time, the low-pressure refrigerant gas existing in advance inside the pulse tube 140 is compressed by the high-pressure refrigerant gas that has flowed in. Thereby, the pressure of the refrigerant gas in the pulse tube 140 becomes higher than the pressure in the buffer tank 190, and the refrigerant gas flows into the buffer tank 190 through the orifice 194 and the gas flow path 192.

  Next, when the exhaust valve 110a is closed and the intake valve 110b is opened, the refrigerant gas in the pulse tube 140 passes through the low temperature end 145b and flows into the low temperature end 125b of the regenerator tube 120. Further, the refrigerant gas passes through the regenerator tube 120 while cooling the regenerator material 122, and is collected by the compressor 110 from the high temperature end 125a through the gas flow path 112 and the intake valve 110b.

  Here, the pulse tube 140 is connected to the buffer tank 190 via the orifice 194. For this reason, the phase of the pressure fluctuation of the refrigerant gas and the phase of the volume change of the refrigerant gas change with a constant phase difference. Due to this phase difference, cold occurs due to expansion of the refrigerant gas at the low temperature end 145 b of the pulse tube 140. The pulse tube refrigerator 100 can cool the object to be cooled connected to the cooling stage 180 by repeating the above operation.

  By the way, in the conventional pulse tube refrigerator, the laminated body which consists of copper metal mesh etc. is used as a heat exchanger installed in the low temperature end side of a pulse tube. The reason for using such a wire mesh is to prevent a large difference in the speed of the refrigerant gas when the refrigerant gas flows into the pulse tube from the regenerator, that is, to obtain a rectifying effect of the refrigerant gas. . The laminated body is filled (bonded) so that the constituent members do not deviate from each other, and then filled in the low temperature end side of the pulse tube.

  However, when the heat exchanger is configured in this way, even if the laminated body is formed with high precision, the side surface of the laminated body and the groove for accommodating the laminated body (in the example of FIG. 1, the communication path 182) A certain amount of gap is inevitable between the inner wall and the inner wall. Therefore, there is a problem that it is difficult to ensure that they are always in thermal contact. For this reason, depending on the contact state between the two, the thermal resistance at the interface changes greatly, resulting in variations in heat exchange properties, and the heat exchange performance of the pulse tube refrigerator decreases. Can occur.

  In order to cope with this problem, it is conceivable that after the laminated body is filled in the groove, the side portion of the laminated body is brazed to the inner wall of the groove.

  However, in this method, although both the laminate and the inner wall of the groove can be brought into contact with each other at a plurality of “points”, it is impossible to bring the side portion of the laminate into contact with the inner wall of the groove as a whole. . Therefore, this method is insufficient as a thermal resistance suppressing effect and does not fundamentally solve the above-mentioned problem.

  On the other hand, in the pulse tube refrigerator according to the present invention, the heat exchanger 149b installed on the low temperature end 145b side of the pulse tube 140 is diffusion bonded to the inner wall of the groove that accommodates the heat exchanger 149b. Has characteristics.

  When the heat exchanger 149b is configured in this way, the side portion of the heat exchanger 149b is always in contact with the inner wall of the groove. Therefore, it is possible to reduce or eliminate the conventional problems that the thermal resistance greatly changes between the two and the heat exchange performance of the pulse tube refrigerator decreases.

  Hereinafter, the features of the present invention will be described in more detail with reference to FIGS.

  FIG. 2 schematically shows a cross section in the vicinity of the groove 189 of the cooling stage 180 to which the low temperature end 145b of the pulse tube 140 is connected. This figure shows a schematic cross section of an example of the heat exchanger 149b used in the present invention. FIG. 3 shows a schematic exploded configuration diagram of an example of the laminated body 150 constituting the heat exchanger 149b.

  As shown in FIG. 2, the heat exchanger 149 b is formed in the groove 189 of the cooling stage 180. The heat exchanger 149 b includes a stacked body 150, and the side surface of the stacked body is diffusion bonded to the inner wall 184 of the groove 189.

  As shown in FIG. 3, in a normal case, the laminated body 150 is configured by laminating a plurality of copper or copper alloy (hereinafter, collectively referred to as “copper (made)”) metal meshes. In the example of FIG. 3, the laminated body 150 is configured by laminating a first wire mesh 152A, a second wire mesh 152B, a third wire mesh 152C ..., and an nth wire mesh 152N. However, the laminated body 150 may be configured by a single copper wire mesh 152A. The contact interfaces of these metal meshes 152A, 152B, 152C ... and 152N are diffusion bonded. Therefore, the thermal contact property at each interface is increased, and the thermal resistance at the interface is decreased.

  The heat exchanger 149b is formed in the groove 189 of the cooling stage 180 by the following method, for example.

  First, each copper wire mesh 152A, 152B, 152C ... and 152N is laminated. Next, the obtained assembly is installed in the groove 189 of the cooling stage 180. Thereafter, the heat exchanger 149 b is formed by performing “diffusion bonding processing” for each cooling stage 180.

  Here, “diffusion bonding treatment” is a general term for a method in which atomic interdiffusion occurs at the interface between members due to heating, whereby the interface bonding is performed. Usually, the diffusion bonding process in the present application is performed in a range of 800 ° C. to 1080 ° C. (for example, 1000 ° C.).

  By such diffusion bonding processing, the interfaces between the metal meshes are brought into close contact with each other, and at the same time, the side surface of the laminate 150 is diffusion bonded to the inner wall 184 of the groove 189.

  Note that the diffusion bonding process between the metal meshes may be performed before the diffusion bonding process between the laminate 150 and the inner wall 184 of the groove 189 (that is, “two-stage” diffusion bonding process).

  In such a configuration of the heat exchanger 149b, the thermal contact between the heat exchanger 149b and the cooling stage 180 can be improved as compared with the case where the laminated body 150 is filled in the groove 189 later, The thermal resistance between them can be significantly suppressed.

  Here, in FIG. 3, the dimensions of the mesh or mesh (opening) of each of the copper wire meshes 152A, 152B, 152C... And 152N may be substantially equal or different.

  In this application, “mesh” means the number of meshes between 1 inch (25.4 mm), and “mesh” means the distance between adjacent wire portions of the wire mesh (the length of the gap). Means.

  When the meshes of the respective metal meshes 152A to 152N are different, the meshes may be increased in order from the first metal mesh 152A to the nth metal mesh 152N in a continuous or stepwise manner (for example, in a step shape). In this case, the first metal mesh 152A having a fine mesh is installed on the side farther from the low temperature end 125b of the regenerator tube 120 (the side closer to the pulse tube 140) than the n-th metal mesh 152N having a coarse mesh. As a result, when the refrigerant gas flows from the regenerator tube 120 to the pulse tube 140, a large fluctuation in the flow velocity of the refrigerant gas is less likely to occur, and a more significant rectification effect is obtained.

  The total number of wire meshes varies depending on the thickness of each wire mesh, but may be in the range of 2 to 200 (for example, 100).

  The mesh of each copper wire mesh is usually in the range of # 16 to # 300, which is in the range of about 1.14 mm to about 0.05 mm in terms of the mesh of the wire mesh. The mesh of each copper wire mesh is preferably in the range of # 60 to # 150 (about 0.303 mm to about 0.104 mm in terms of mesh).

  Each wire mesh may be rolled. A rolled wire mesh is disclosed in Japanese Patent Application Laid-Open No. 2003-28526. As shown to FIG. 2 (A) of Unexamined-Japanese-Patent No. 2003-28526, by rolling a metal mesh, the contact area between metal meshes increases. The thermal contact resistance between the wire meshes is reduced, and the heat exchange efficiency is improved. The thickness of the wire mesh after the rolling process is in the range of 0.4 to 0.99, where 1 is the value before the process. This thickness is preferably in the range of 0.6 to 0.8.

  In the example of FIG. 2, the side surface of the heat exchanger 149 b is diffusion bonded to the inner wall 184 of the structure 189 of the cooling stage 180. However, the embodiment of the present invention is not limited to this. For example, the side surface of the heat exchanger 149b may be diffusion bonded to the inner wall on the low temperature end 145b side of the cylinder 141 constituting the pulse tube 140.

  Next, the configuration of another heat exchanger 149b-2 will be described with reference to FIG. FIG. 4 schematically shows a cross section near the groove 189 of the cooling stage 180 to which the low temperature end 145b of the pulse tube 140 is connected. This figure shows a schematic cross section of an example of the heat exchanger 149b-2 used in the present invention.

  As shown in FIG. 4, the heat exchanger 149 b-2 is formed in the groove 189 of the cooling stage 180. This heat exchanger 149b-2 has the same laminate as the heat exchanger 149b shown in FIG. However, the heat exchanger 149b-2 further has a feature of including a housing 159 that accommodates the wire mesh laminate 150. The housing 159 is made of copper or a copper alloy. In addition, the housing 159 has an upper surface and a lower surface that are open, and has a side dimension that substantially matches the inner diameter of the groove 189. The side surface of the metal mesh laminate 150 is diffusion bonded to the inner wall of the side surface of the housing 159.

  The heat exchanger 149b-2 can be formed by stacking the metal meshes 152A to 152N and filling the casing 159, and then subjecting the casing 159 to diffusion bonding. Thereafter, the housing 159 is installed in the groove 189 of the cooling stage 180, and the housing 159 is brazed to the inner wall 184 of the groove 189 of the cooling stage 180.

  Here, when the case 159 and the inner wall 184 are brazed, the close contact and contact degree at the contact interface are better than when the conventional laminate and the inner wall are brazed directly. It is necessary to pay attention to. This is because the side surface of the laminated body usually has end portions of a plurality of members, so that it is difficult to sufficiently smooth the surface with high dimensional accuracy, whereas the housing 159 is configured by a single member. Therefore, the side surface can be smoothed with high accuracy and relatively easily.

  Therefore, even in the configuration as shown in FIG. 4, the thermal contact between the heat exchanger 149 b-2 and the cooling stage 180 can be improved as compared with the conventional heat exchanger, and the thermal resistance between the two is significant. Can be suppressed.

  In the example of FIG. 4, the heat exchanger 149 b-2 is directly installed in the structure 189 of the cooling stage 180. However, the embodiment of the present invention is not limited to this. For example, the outside of the heat exchanger 149b-2 may be in contact with the low temperature end 145b side of the cylinder 141 constituting the pulse tube 140. In this case, the housing 159 of the heat exchanger 149b-2 is brazed to the inner wall of the cylinder 141.

  In the above example, the case where the heat exchanger 149b and the heat exchanger 149b-2 have the laminated body 150 made of a copper wire mesh has been described. However, the present invention is not limited to such an embodiment.

  In FIG. 5, the structure of another laminated body used for the heat exchanger 149b and the heat exchanger 149b-2 is shown.

  In FIG. 5, a laminated body 150A is configured by laminating a first wire mesh 153A, a second wire mesh 153B, a third wire mesh 153C, a fourth wire mesh 153D, and an nth wire mesh 153N in this order. The Note that, similarly to the above-described laminated body 150, finally, the interfaces between the metal meshes are diffusion-bonded.

  Here, the second wire mesh 153B to the nth wire mesh 153N are made of copper, whereas the first wire mesh 153A is made of a metal or alloy other than copper. For example, the first wire mesh 153A may be stainless steel (SUS304, 316, etc.) or nickel. Stainless steel and nickel are more rigid than copper. Therefore, when the first metal mesh 153A is made of stainless steel or nickel, the rigidity of the finally obtained laminated body 150A can be increased, and the laminated body 150 is deformed by the pressure of the refrigerant gas during use. Less likely.

  The first wire mesh 153A may have a larger mesh (that is, a smaller mesh) than other wire meshes. In this case, the laminated body 150A has a groove 189 such that the first wire mesh 153A side is a side far from the low temperature end 125b of the regenerator tube 120 (in the example of FIGS. 2 and 4, the upper side). Installed inside. As a result, a high rectifying effect can be obtained for the refrigerant gas reciprocating between the regenerator tube 120 and the pulse tube 140.

  In general, a copper wire mesh has a problem that a mesh is large and it is difficult to manufacture a fine mesh due to limitations in processing technology and cost (for example, the maximum value of the mesh is about # 100. The minimum value of the mesh is about 0.134 to 0.154 mm). However, in the case of a non-copper wire mesh such as stainless steel, a mesh having a large mesh and a fine mesh can be obtained relatively easily. Therefore, by combining the two types of materials, a wide range of designs can be made regarding the rectification of the heat exchangers 149b and 149b-2.

  For example, the mesh of the first wire mesh 153A is in the range of # 30 to # 500, and preferably in the range of # 60 to # 400. This corresponds to about 0.577 mm to about 0.026 mm and about 0.253 mm to about 0.034 mm, respectively, in terms of mesh. On the other hand, the meshes of the second wire mesh 153B to the n-th wire mesh 153N are in the range of # 16 to # 300, and preferably in the range of # 60 to # 150. This corresponds to about 1.14 mm to about 0.05 mm and about 0.303 mm to about 0.104 mm, respectively, in terms of mesh. As described above, the second metal mesh 153B to the n-th metal mesh 153N may have the same or different meshes or meshes.

  The total number of wire meshes varies depending on the thickness of each wire mesh, but may be in the range of 2 to 200 (for example, 100).

  As described above, the laminated body 150A is installed in the groove 189 of the cooling stage 180, and the heat exchanger 149b is formed by subjecting this to the diffusion bonding process. Alternatively, the laminated body 150A is installed in the casing 159, and after diffusion-bonding this, the casing 159 is installed in the groove 189 of the cooling stage 180, and the casing 159 and the inner wall 184 are brazed. Thus, the heat exchanger 149b-2 is formed. The diffusion bonding process is performed in a range of 800 ° C. to 1080 ° C. (for example, 1000 ° C.), for example.

  In FIG. 6, the structure of another laminated body used for the heat exchanger 149b and the heat exchanger 149b-2 is shown.

  In FIG. 6, the laminated body 150B is configured by laminating a first wire mesh 154A, a second wire mesh 154B, a third wire mesh 154C, a fourth wire mesh 154D, and an nth wire mesh 154N in this order. The Note that, similarly to the above-described laminates 150 and 150A, finally, the interfaces between the wire meshes are diffusion-bonded.

  The second wire mesh 154B, the fourth wire mesh 154D, and the sixth wire mesh 154F to the n-th wire mesh 154N are made of copper. In contrast, the first wire mesh 154A, the third wire mesh 154C, and the fifth wire mesh 154E are made of a metal or alloy other than copper. For example, the first wire mesh 154A, the third wire mesh 154C, and the fifth wire mesh 154E are made of stainless steel (SUS304, 316, etc.) or nickel. The first wire mesh 154A, the third wire mesh 154C, and the fifth wire mesh 154E may be made of the same material or different materials.

  In the configuration of this figure, the cycle C in which the non-copper wire mesh and the copper wire mesh are alternately laminated is repeated three times.

  Three of the first wire mesh 154A, the third wire mesh 154C, and the fifth wire mesh 154E have larger meshes (that is, smaller meshes) than other wire meshes. For example, the meshes of the first wire mesh 154A, the third wire mesh 154C, and the fifth wire mesh 154E are in the range of # 30 to # 500 (in terms of mesh, about 0.577 mm to about 0.026 mm). A range of 60 to # 400 (in terms of mesh, about 0.253 mm to about 0.034 mm) is preferable. On the other hand, the meshes of the remaining copper wire meshes 154B, 154D, 154F to 154N are in the range of # 16 to # 300 (about 1.14 mm to about 0.05 mm in terms of mesh), and # 60 to # 150 (mesh It is preferably in the range of about 0.303 mm to about 0.104 mm in terms of conversion. The copper wire mesh may have the same or different mesh size. When the sizes of the meshes of the copper metal meshes 154B to 154N are different, the meshes may increase continuously or stepwise (for example, stepwise) in the order of the second metal mesh 154B to the nth metal mesh 154N.

  The total number of wire meshes may be in the range of 2 to 200 (for example, 100), depending on the thickness of each wire mesh.

  In use, the laminate 150B shown in FIG. 6 is such that the first wire mesh 154A is on the side far from the communication path 182 of the cooling stage 180 (in the example of FIGS. 2 and 4, it is on the upper side). And installed in the cooling stage 180.

  In the example of FIG. 6, the laminated body 150 </ b> B including three non-copper wire meshes and a cycle number C of 3 has been described, but in the laminate body 150 </ b> B, the number of non-copper wire meshes and the cycle number C are Not particularly limited. The number of non-copper wire meshes may be two, four, six or more, for example. Further, the number of repetitions C may be two times, four times, or six times or more. For example, the alternate arrangement of the non-copper and copper wire meshes may be repeated from the first wire mesh to the nth wire mesh (that is, over the entire laminated body 150B).

  The example of the embodiment according to the present invention has been described above with reference to the drawings. However, it will be apparent to those skilled in the art that the present invention is not limited to the above-described configuration. For example, in the above-described example, the pulse tube refrigerator 100 is a single stage type. However, the present invention can also be applied to a two-stage or three-stage multi-stage pulse tube refrigerator.

  Actually, the pulse tube refrigerator having the heat exchanger 149b as shown in FIG. 2 formed in the groove of the cooling stage was operated under normal conditions, and the temperature of the cooling stage was measured. A laminate 150A having the configuration shown in FIG. 5 was used as the laminate of the heat exchanger 149b. As the uppermost wire mesh 153A, a wire mesh made of SUS304 having a mesh of # 250 was used. Further, a copper wire mesh having a mesh of # 80 was used for the second and subsequent wire meshes.

  As a result of the measurement, the temperature of the cooling stage was about 36.4K (Kelvin). On the other hand, a pulse tube refrigeration provided with a conventional heat exchanger (having a copper laminate having a mesh of # 80 and the side portions of the laminate are not diffusion bonded to the inner wall of the groove) in the groove of the cooling stage. When the same measurement was performed in the machine, the temperature of the cooling stage was about 40.2 K (Kelvin).

  From this result, it was confirmed that the cooling capacity of the pulse tube refrigerator according to the present invention is improved as compared with the conventional case.

  The present invention can be applied to a single-stage or multi-stage pulse tube refrigerator applied to a low-temperature system such as a nuclear magnetic resonance diagnostic apparatus, a superconducting magnet apparatus, or a cryopump.

DESCRIPTION OF SYMBOLS 100 Pulse tube refrigerator 110 Compressor 110a Exhaust valve 110b Intake valve 112 Gas flow path 115 Flange 120 Regenerator tube 121 Cylinder 122 Regenerator material 125a High temperature end of regenerator tube 125b Cold end of regenerator tube 140 Pulse tube 141 Cylinder 145a High temperature of pulse tube End 145b Cold end of pulse tube 149a, 149b Heat exchanger 150 Laminate 150A Another laminate 150B Yet another laminate 152A, 153A, 154A First wire mesh 152B, 153B, 154B Second wire mesh 152C, 153C, 154C Third wire mesh 159 Housing 180 Cooling stage 182 Communication path 184 Inner wall 189 Groove 190 Buffer tank 192 Gas flow path 194 Orifice.

Claims (14)

A pulse tube refrigerator in which the low temperature end of the pulse tube and the low temperature end of the regenerator tube are communicated by a communication path,
On the low temperature end side of the pulse tube of the communication path, a heat exchanger is installed,
The heat exchanger has a laminate including at least first and second wire meshes,
The first and second wire meshes are both made of copper or a copper alloy,
The interface between each wire mesh is diffusion bonded,
A pulse tube refrigerator, wherein a side surface of the laminate is diffusion bonded to an inner wall constituting the communication path. A pulse tube refrigerator in which the low temperature end of the pulse tube and the low temperature end of the regenerator tube are communicated by a communication path,
On the low temperature end side of the pulse tube of the communication path, a heat exchanger is installed,
The heat exchanger includes a laminate including at least first and second wire meshes, and a housing.
The first and second wire meshes and the casing are both made of copper or a copper alloy,
The interface between each wire mesh is diffusion bonded,
The laminate is housed in the housing,
The pulse tube refrigerator, wherein the side surface of the laminate is diffusion bonded to the inner wall of the housing. The laminate further includes a third wire mesh made of a metal different from copper or a copper alloy at the top,
The interface between each wire mesh is diffusion bonded,
The said laminated body is arrange | positioned in the said communicating path so that the side of the said 3rd metal net | network may be furthest away from the low-temperature end of the said cool storage pipe, The any one of Claim 1 or 2 characterized by the above-mentioned. Pulse tube refrigerator. The laminate further includes a fourth wire mesh made of a metal different from copper or a copper alloy,
The interface between each wire mesh is diffusion bonded,
The pulse tube refrigerator according to claim 3, wherein the laminated body is laminated in the order of the third wire mesh, the first wire mesh, the fourth wire mesh, and the second wire mesh. The laminate is configured by laminating six or more wire meshes,
The laminate is composed of an alternating repeating structure of a wire mesh made of a metal different from copper or a copper alloy and a wire mesh made of copper or a copper alloy throughout,
The pulse tube refrigerator according to claim 4, wherein an interface between the metal meshes is diffusion bonded.   6. The size of a mesh of a wire mesh made of a metal different from the copper or copper alloy is in a range of 0.02 mm to 0.58 mm. 6. Pulse tube refrigerator.   7. The pulse tube refrigerator according to claim 1, wherein the wire mesh is rolled.   8. The pulse tube refrigerator according to claim 7, wherein the thickness of the rolled wire mesh is in a range of 0.4 to 0.99, where 1 is a value before processing.   The pulse tube refrigerator according to any one of claims 3 to 8, wherein the metal other than the copper or the copper alloy is stainless steel or nickel.   The pulse tube refrigerator according to any one of claims 4 to 9, wherein the mesh size of the wire mesh made of a metal different from each copper or copper alloy is substantially equal.   The size of a mesh of a wire mesh made of a metal different from each copper or copper alloy is smaller than the size of a mesh of a wire mesh made of each copper or copper alloy. Pulse tube refrigerator as described in 1.   The pulse tube refrigerator according to any one of claims 1 to 11, wherein a mesh size of the copper or copper alloy wire mesh is in a range of 0.05 mm to 1.14 mm.   The pulse tube refrigerator according to any one of claims 1 to 12, wherein the mesh size of each copper or copper alloy wire mesh is substantially equal.   The size of the mesh of each copper or copper alloy wire mesh decreases continuously or stepwise from the wire mesh closest to the cold end of the regenerator tube toward the stacking direction of the laminate. The pulse tube refrigerator according to any one of claims 1 to 12.

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