JP2012087970A - Cold storage refrigerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cold storage refrigerator capable of preventing wear of an outer peripheral surface of a displacer.SOLUTION: The cold storage refrigerator includes: a cylinder 12; a displacer 14 of a roller shape provided in the cylinder 12 reciprocably along the cylinder 12, forming an expansion space 22 at one end in the cylinder 12 and forming therein a cooling medium gas flow channel 24 for supplying and discharging a cooling medium gas in the expansion space 22; and a cold-storage material 18 stored in the cooling medium gas flow channel 24 and storing the cold generated by expanding the cooling medium gas supplied to the expansion space 22 when the displacer 14 reciprocates along the cylinder 12. The displacer 14 has a radius R22 at a low temperature end smaller than a radius R21 at a high temperature end. A low temperature end of the cooling medium gas flow channel 24 communicates with an opening 46b provided in an outer peripheral surface of the displacer 14.

Description

  The present invention relates to a regenerator type refrigerator having a regenerator containing a regenerator material using a refrigerant gas such as helium gas.

  For example, in order to obtain an extremely low temperature of about 4K, a regenerator type refrigerator having a regenerator that stores a regenerator material using a refrigerant gas such as helium gas is used. In addition, as a regenerator type refrigerator, for example, a Gifford-McMahon (GM) refrigerator is used.

  The GM refrigerator generates cold by supplying a refrigerant gas made of, for example, helium gas from a compressor to an expansion space formed in the cylinder, and expanding the supplied refrigerant gas in the expansion space. In order to obtain a cryogenic temperature by the generated cold heat, the GM refrigerator is usually configured by a plurality of stages.

  Each stage of the GM refrigerator has a cylinder and a displacer provided in the cylinder. The displacer is provided in the cylinder so as to be capable of reciprocating along the cylinder, and forms an expansion space between one end of the displacer and the cylinder. In addition, a refrigerant gas flow path for supplying and discharging refrigerant gas to and from the expansion space is formed inside the displacer. In addition, the refrigerant gas passage formed inside the displacer contains a regenerator material for accumulating cold heat in contact with the refrigerant gas.

  The displacer has an outer diameter that is slightly smaller than the inner diameter of the cylinder in order to expand or contract the expansion space hermetically by reciprocating along the cylinder. A seal is provided between the outer peripheral surface of the displacer and the inner peripheral surface of the cylinder to keep the gap between the displacer and the cylinder airtight. Conventionally, seal rings, clearance seals, labyrinth seals, spiral groove seals and the like have been used as such seals (see, for example, Patent Document 1).

Japanese Patent No. 2659684

  However, the above-described regenerator refrigerators such as the GM refrigerator have the following problems.

  For example, when a clearance seal is used, the displacer may be eccentric due to the distribution of refrigerant gas pressure due to a hydraulic lock phenomenon, which will be described later, and contacted and fixed to the inner peripheral surface of the cylinder, causing the displacer to reciprocate. It may not be possible. Further, when the GM refrigerator is operated for a long time in a state where a part of the displacer is in contact with and fixed to the inner peripheral surface of the cylinder, the displacer is worn because only the contact portion slides. When the displacer is worn, the gap between the cylinder and the displacer increases, the amount of refrigerant gas leaked from the expansion space increases, and the refrigeration capacity of the GM refrigerator may decrease. Alternatively, when the displacer wears further, there is a problem that the life of the GM refrigerator is shortened.

  In particular, when the cylinder is placed at an angle with respect to the vertical direction, including when the cylinder is placed horizontally, a part of the outer peripheral surface of the displacer is decentered by the weight of the displacer and easily contacts the inner peripheral surface of the cylinder. Therefore, the above problem becomes remarkable. However, even when the cylinder is arranged vertically, due to the dimensional tolerance of the outer diameter of the displacer or the dimensional tolerance of the inner diameter of the cylinder, a part of the outer peripheral surface of the displacer contacts the inner peripheral surface of the cylinder, and the displacer It may wear out. Therefore, the above-described problem is a common problem not only when the cylinder is inclined with respect to the vertical direction but also when the cylinder is vertically disposed.

  This invention is made | formed in view of said point, and provides the regenerator type refrigerator which can prevent abrasion of the outer peripheral surface of a displacer.

  In order to solve the above problems, the present invention is characterized by the following measures.

  The present invention is provided in a cylinder and in the cylinder so as to be capable of reciprocating along the cylinder, and forms an expansion space at one end of the cylinder, and supplies and discharges refrigerant gas into the expansion space. A displacer having a rotating body in which a refrigerant gas flow path is formed, and is accommodated in the refrigerant gas flow path, and is moved into the expansion space when the displacer reciprocates along the cylinder. A cold storage material for storing cold heat generated by expanding the supplied refrigerant gas, and the displacer has a low temperature end diameter smaller than a high temperature end diameter, and the low temperature end of the refrigerant gas flow path It is a regenerator type refrigerator that communicates with an opening provided on the outer peripheral surface of the displacer.

  Further, the present invention is the above-described regenerator-type refrigerator, wherein the refrigerant gas flow path has a plurality of low-temperature ends provided at equal intervals along the circumferential direction on the outer peripheral surface of the displacer. It communicates with the opening.

  Further, according to the present invention, in the above regenerator type refrigerator, the displacer has a monotonously decreasing diameter from the high temperature end to a position where the opening is provided.

  According to the present invention, in the regenerator type refrigerator, it is possible to prevent the outer peripheral surface of the displacer from being worn.

It is a schematic sectional drawing which shows the structure of the GM refrigerator which concerns on 1st Embodiment. It is a schematic sectional drawing which shows the structure of the 1st step displacer with the 1st step cylinder in the GM refrigerator which concerns on 1st Embodiment. It is a schematic sectional drawing which shows the structure of the 2nd stage displacer in the GM refrigerator which concerns on 1st Embodiment with a 2nd stage cylinder. It is a schematic sectional drawing which shows another example of a structure of a 2nd stage displacer with a 2nd stage cylinder. It is a cross-sectional view which follows the AA line of FIG. It is sectional drawing which shows typically a mode that refrigerant gas is supplied and discharged | emitted to expansion space, when the 2nd stage displacer of the GM refrigerator which concerns on 1st Embodiment is eccentric. It is sectional drawing which shows typically a mode that refrigerant gas is supplied to expansion space, when the 2nd stage displacer of the GM refrigerator which concerns on a comparative example is eccentric. It is sectional drawing which shows typically a mode that refrigerant gas is discharged | emitted from expansion space, when the 2nd stage displacer of the GM refrigerator which concerns on a comparative example is eccentric. It is a schematic sectional drawing which shows the structure of the 2nd stage displacer with the 2nd stage cylinder in the GM refrigerator which concerns on the modification of 1st Embodiment. It is a schematic sectional drawing which shows the structure of the 1st stage displacer with the 1st stage cylinder in the GM refrigerator which concerns on 2nd Embodiment.

Next, a mode for carrying out the present invention will be described with reference to the drawings.
(First embodiment)
A GM refrigerator according to the first embodiment will be described with reference to FIG. This GM refrigerator is an example in which the regenerator type refrigerator according to the present invention is applied to a GM refrigerator, and has a two-stage configuration suitable for obtaining a cryogenic temperature of about several K to 20K.

  FIG. 1 is a schematic cross-sectional view showing the configuration of the GM refrigerator according to the present embodiment.

  The GM refrigerator includes a compressor 10, a first stage cylinder 11, a second stage cylinder 12, a first stage displacer 13, a second stage displacer 14, a crank mechanism 15, a refrigerant gas passage 16, and a cold storage material 17. , 18, heat stations 19 and 20, expansion spaces 21 and 22, and hollow spaces (refrigerant gas flow paths) 23 and 24.

  In the arrangement shown in FIG. 1, the upper ends of the first stage cylinder 11, the second stage cylinder 12, the first stage displacer 13 and the second stage displacer 14 are high-temperature ends, and the lower ends are low-temperature ends. (The same applies to FIGS. 2 to 4).

The compressor 10 compresses helium gas (refrigerant gas) to about 20 Kgf / cm ² to generate high-pressure helium gas. The generated high-pressure helium gas is supplied into the first stage cylinder 11 via the intake valve V1 and the refrigerant gas flow path 16. Further, the low-pressure helium gas discharged from the first stage cylinder 11 is recovered by the compressor 10 via the refrigerant gas passage 16 and the exhaust valve V2.

  A second stage cylinder 12 is coupled to the first stage cylinder 11. A first stage displacer 13 and a second stage displacer 14 connected to each other are accommodated in the first stage cylinder 11 and the second stage cylinder 12, respectively.

  From the first stage cylinder 11, the drive shaft Sh extends upward and is coupled to a crank mechanism 15 coupled to the drive motor M.

  The first stage displacer 13 is provided in the first stage cylinder 11 so as to be capable of reciprocating along the first stage cylinder 11. The first stage displacer 13 forms an expansion space 21 at one end of the first stage cylinder 11. The first stage displacer 13 has, for example, a rotating body shape such as a substantially cylindrical shape having different diameters at both ends.

  Further, a hollow space (refrigerant gas flow path) 23 for supplying and discharging refrigerant gas to and from the expansion space 21 is formed inside the first stage displacer 13. When the first stage displacer 13 reciprocates along the first stage cylinder 11, the first stage displacer 13 generates cold heat by expanding the refrigerant gas supplied to the expansion space 21.

  A cold storage material 17 is accommodated in the hollow space 23. When discharging the refrigerant gas from the expansion space 21, the cold storage material 17 contacts the discharged refrigerant gas and stores cold heat. That is, the cool storage material 17 stores the cold generated by expanding the refrigerant gas supplied to the expansion space 21 when the first stage displacer 13 reciprocates along the first stage cylinder 11.

  The second stage displacer 14 is provided in the second stage cylinder 12 so as to be capable of reciprocating along the second stage cylinder 12. The second stage displacer 14 forms an expansion space 22 at one end of the second stage cylinder 12. The second stage displacer 14 has, for example, a rotating body shape such as a substantially cylindrical shape having different diameters at both ends.

  In addition, a hollow space (refrigerant gas flow path) 24 for supplying and discharging refrigerant gas to and from the expansion space 22 is formed inside the second stage displacer 14. The second stage displacer 14 generates cold by expanding the refrigerant gas supplied to the expansion space 22 when reciprocating along the second stage cylinder 12.

  A cold storage material 18 is accommodated in the hollow space 24. When discharging the refrigerant gas from the expansion space 22, the cold storage material 18 contacts the discharged refrigerant gas and stores cold heat. That is, the cool storage material 18 stores the cold generated by expanding the refrigerant gas supplied to the expansion space 22 when the second stage displacer 14 reciprocates along the second stage cylinder 12.

  The first stage heat station 19 is thermally coupled so as to surround the lower end (low temperature end) of the first stage cylinder 11, and so as to surround the lower end (low temperature end) of the second stage cylinder 12. The second stage heat station 20 is thermally coupled.

  The first stage cylinder 11 and the second stage cylinder 12 are preferably formed of, for example, a stainless steel (for example, SUS304). As a result, the first-stage cylinder 11 and the second-stage cylinder 12 can have high strength, low thermal conductivity, and high helium gas shielding ability.

  The first stage displacer 13 and the second stage displacer 14 are preferably formed of, for example, cloth-containing phenol (bakelite) or the like. Accordingly, the first stage displacer 13 and the second stage displacer 14 can be reduced in weight, wear resistance and strength can be improved, and the amount of heat entering from the high temperature side to the low temperature side can be reduced.

  The first-stage regenerator material 17 is preferably composed of, for example, a wire mesh, and the second-stage regenerator material 18 is preferably composed of, for example, a lead ball or a magnetic regenerator material. Thereby, a sufficiently high heat capacity can be secured in the low temperature region.

  In the GM refrigerator configured as described above, cold heat is generated as follows.

  High-pressure helium gas, which is refrigerant gas, supplied from the compressor 10 via the intake valve V <b> 1 is supplied into the first-stage cylinder 11 via the refrigerant gas flow path 16. Then, the gas is supplied to the first-stage expansion space 21 through the opening (refrigerant gas flow path) 23a, the hollow space (refrigerant gas flow path) 23 in which the regenerator material 17 is accommodated, and the opening (refrigerant gas flow path) 23b. Is done.

  The high-pressure helium gas supplied to the first-stage expansion space 21 further includes an opening (refrigerant gas flow path) 24a, a hollow space (refrigerant gas flow path) 24 in which the regenerator 18 is accommodated, and an opening (refrigerant gas flow path). ) Is supplied to the second stage expansion space 22 through 24b.

  Note that the refrigerant gas flow paths 23a, 23b, 24a, and 24b are functionally described to explain the flow of the refrigerant gas, and are different from the actual structure described with reference to FIG.

  When the intake valve V1 is closed and the exhaust valve V2 is opened, the high-pressure helium gas in the second-stage cylinder 12 and the first-stage cylinder 11 follows the path opposite to that in the intake air, and the refrigerant gas flow path. 16. Recovered to the compressor 10 via the exhaust valve V2.

  During the operation of the GM refrigerator, the rotational driving force of the driving motor M is converted into the reciprocating driving force of the driving shaft Sh by the crank mechanism 15. The first stage displacer 13 and the second stage displacer 14 are moved up and down by the drive shaft Sh as shown by arrows in FIG. 1 (to the first stage cylinder 11 and the second stage cylinder 12 respectively). Along).

  When the first stage displacer 13 and the second stage displacer 14 are driven to the opposite side (downward in FIG. 1) by the drive shaft Sh, the intake valve V1 is opened and the exhaust valve V2 is closed. Then, high-pressure helium gas is supplied to the expansion space 21 in the first stage cylinder 11 and the expansion space 22 in the second stage cylinder 12 (supply process).

  Further, when the first stage displacer 13 and the second stage displacer 14 are driven to the drive shaft Sh side (upward in FIG. 1) by the drive shaft Sh, the intake valve V1 is closed and the exhaust valve V2 is opened. Then, the expansion space 21 in the first stage cylinder 11 and the expansion space 22 in the second stage cylinder 12 become low pressure, and helium gas is discharged from the expansion space 21 and the expansion space 22 to the compressor 10. Collected (discharge process).

  At this time, cold energy is generated by the expansion of the helium gas in the expansion spaces 21 and 22. When the cooled helium gas that generates cold and is discharged from the expansion spaces 21 and 22 contacts the cold storage materials 17 and 18 to exchange heat, the cold storage materials 17 and 18 are cooled. That is, the generated cold energy is stored in the cold storage materials 17 and 18.

  The high-pressure helium gas supplied in the next supply process is cooled by being supplied through the cold storage materials 17 and 18. As the cooled helium gas expands in the expansion spaces 21 and 22, the cooling further proceeds.

  By repeating the supply process and the discharge process as described above, the expansion space 21 in the first stage cylinder 11 is cooled to a temperature of about 40K to 70K, for example, and the expansion in the second stage cylinder 12 is performed. The space 22 is cooled to a temperature of about several K to 20K, for example.

  Next, a detailed configuration of the first stage displacer 13 will be described with reference to FIG. FIG. 2 is a schematic cross-sectional view showing the configuration of the first stage displacer 13 together with the first stage cylinder 11 in the GM refrigerator according to the present embodiment. In addition, illustration of the heat station 19 is abbreviate | omitted in FIG.

  The first stage displacer 13 includes a rotating body-shaped member 30.

  The rotating body-shaped member 30 has an upper lid and a rotating body shape, and its lower end is open. A flange 31 having a diameter substantially equal to the outer diameter of the rotating body-shaped member 30 is attached to the upper surface of the upper cover of the rotating body-shaped member 30. An opening 32 (23a shown in FIG. 1) is provided in the upper lid of the flange 31 and the rotating body-shaped member 30. A high temperature end of the hollow space (refrigerant gas flow path) 23 communicates with the opening 32. On the upper surface of the flange 31, a drive shaft Sh for vertically driving the rotary member 30 in the direction of the arrow in FIG.

  A wire mesh (not shown) is disposed in the rotary member 30 so as to be in close contact with the upper surface. Under the wire mesh, a regenerator material 17 such as a copper wire mesh is filled. Another wire mesh (not shown) is disposed under the cold storage material 17.

  Further, a lid member 33 is inserted into the lower open end of the rotating body-shaped member 30 and bonded to the rotating body-shaped member 30. The lid member 33 is a blind lid and hermetically closes the opening at the lower end of the rotating body-shaped member 30. Further, a connection mechanism 50 for connecting to the second stage displacer 14 is attached to the lower surface of the lid member 33.

  An opening 34 (23b shown in FIG. 1) is provided on the outer peripheral surface of the rotating body-shaped member 30 at a height at which the lower wire mesh of the regenerator material 17 is disposed. The opening 34 communicates with the low temperature end of the hollow space (refrigerant gas flow path) 23.

  The rotating body-shaped member 30 and the lid member 33 are preferably formed of cloth-containing phenol, for example. Thereby, about the rotary body-shaped member 30 and the cover member 33, while reducing weight, abrasion resistance and intensity | strength can be improved and the amount of invasion heat | fever from a high temperature side to a low temperature side can be reduced.

  A gap D <b> 11 is formed between the outer peripheral surface of the rotating body-shaped member 30 and the inner peripheral surface of the first stage cylinder 11. In order to stably drive the first stage displacer 13 back and forth, the gap D11 is preferably 0.01 mm or more. In order to prevent the refrigerant gas from flowing through the gap D11, the gap D11 is preferably 0.03 mm or less.

  One spiral groove 35 may be formed on the outer peripheral surface of the rotating body-shaped member 30 from the upper end (high temperature end) to the height at which the opening 34 is formed. As the shape of the spiral groove 35, for example, the width is about 2 mm, the depth is about 0.6 mm, and the pitch is about 4 mm.

  The outer diameter of the portion below the opening 34 of the rotating body-shaped member 30 may be slightly smaller than the outer diameter of the portion above the opening 34. At this time, a gap D <b> 12 is formed between the inner peripheral surface of the first stage cylinder 11 and the outer peripheral surface of the rotating body-shaped member 30 in a portion below the opening 34. The gap D <b> 12 forms a refrigerant gas flow path that connects the inside of the rotating body-shaped member 30 and the expansion space 21.

  When the inner diameter of the first stage cylinder 11 is, for example, 82 mm, the outer diameter of the rotating body-shaped member 30 can be, for example, (82-2 × D11) mm, and the inner diameter can be, for example, 72 mm. Further, the outer diameter of the lower portion of the rotating body-shaped member 30 than the opening 34 and the outer diameter of the flange 31 can be set to 81.5 mm, for example (D12 = 0.25 mm at this time). Further, the axial length of the rotating body-shaped member 30 can be set to 150 mm, for example, and the thickness of the flange 31 can be set to 10 mm, for example.

  Next, a detailed configuration of the second stage displacer 14 will be described with reference to FIG.

  In the present embodiment, the second stage displacer 14 has a diameter at the low temperature end smaller than the diameter at the high temperature end. Further, in the second stage displacer 14, the low temperature end of the hollow space (refrigerant gas flow path) 24 communicates with an opening 46b (24b shown in FIG. 1) provided on the outer peripheral surface of the second stage displacer 14. Yes.

  FIG. 3 is a schematic cross-sectional view showing the configuration of the second stage displacer 14 together with the second stage cylinder 12 in the GM refrigerator according to the present embodiment. In addition, illustration of the heat station 20 is abbreviate | omitted in FIG.

  The second stage displacer 14 includes a rotating body-shaped member 40.

  The rotator-shaped member 40 has a rotator shape whose upper and lower ends are open. The upper end of the rotating body-shaped member 40 is connected to the first stage displacer 13 via the connecting mechanism 50. A lid member 41 is inserted and bonded to the lower end of the rotating body-shaped member 40. A wire mesh 42 is disposed on the lid member 41, and a felt plug 43 is disposed thereon.

  The outer diameter (hereinafter also referred to as “diameter”) at the upper end of the rotating body-shaped member 40 (the high temperature end of the second stage displacer 14) is R21. Further, the outer diameter (hereinafter also referred to as “diameter”) at the lower end of the lid member 41 (the low temperature end of the second stage displacer 14) is R22.

  The rotating body-shaped member 40 and the lid member 41 are preferably formed of cloth-containing phenol, for example. Thereby, about the rotary body-shaped member 40 and the cover member 41, while reducing weight, abrasion resistance and intensity | strength can be improved and the amount of invasion heat | fever from a high temperature side to a low temperature side can be reduced.

  As described above, the felt plug 43 is filled with the regenerator material 18 formed of, for example, a lead ball. A felt plug 44 is disposed on the cold storage material 18, and a punching metal 45 is disposed on the felt plug 44.

  A connecting mechanism 50 for connecting to the first stage displacer 13 is attached to the upper end (high temperature end) of the rotating body-shaped member 40. Further, an opening 46 a (24 a shown in FIG. 1) is provided around the coupling mechanism 50 at the upper end (high temperature end) of the rotating body-shaped member 40. The high temperature end of the hollow space (refrigerant gas flow path) 24 communicates with the opening 46a.

  On the outer peripheral surface of the rotating body-shaped member 40, an opening 46b that forms a refrigerant gas flow path is provided at a height position of the wire mesh 42. The low temperature end of the hollow space (refrigerant gas flow path) 24 communicates with the opening 46b.

  In the second stage displacer 14, the diameter R22 at the low temperature end is smaller than the diameter R21 at the high temperature end. That is, the diameter R22 at the lower end of the lid member 41 (the low temperature end of the second stage displacer 14) is smaller than the diameter R21 of the high temperature end of the rotating body-shaped member 40. This prevents the second stage displacer 14 from coming into contact with the inner peripheral surface of the second stage cylinder 12 when supplying and discharging the refrigerant gas to and from the expansion space 22, and wear of the second stage displacer 14. Can be prevented.

  The lid member 41 may have a cylindrical shape with the diameter of the upper end (high temperature end) equal to the diameter R22 of the lower end (low temperature end). Further, the lid member 41 may have a lower end (low temperature end) of the rotating body shape member 40. The diameter may be equal to the diameter R22 of the lower end (low temperature end) of the lid member 41. In this case, the diameter R22 of the lower end (low temperature end) of the rotating body shaped member 40 is smaller than the diameter R21 of the upper end (high temperature end) of the rotating body shaped member 40.

  Furthermore, the diameter of the second stage displacer 14 may monotonously decrease from the upper end (high temperature end) of the rotating body-shaped member 40 to the lower end (low temperature end) of the rotating body-shaped member 40. That is, the diameter of the second stage displacer 14 may monotonously decrease from the upper end (high temperature end) of the rotating body-shaped member 40 to the position where the opening 46b is provided. Thereby, the flow of the refrigerant gas when the second stage displacer 14 reciprocates becomes smoother, and the effect of preventing wear of the second stage displacer 14 described later can be improved.

  The clearance between the outer peripheral surface of the upper end (high temperature end) of the second stage displacer 14 and the inner peripheral surface of the second stage cylinder 12 is D21, and the outer peripheral surface of the lower end (low temperature end) of the second stage displacer 14. And the inner peripheral surface of the second stage cylinder 12 is D22. At this time, the gap D22 can be made larger than the gap D21 by making the diameter R22 of the low temperature end of the second stage displacer 14 smaller than the diameter R21 of the high temperature end of the second stage displacer 14.

  When the inner diameter of the second stage cylinder 12 is, for example, 35 mm, the outer diameter at the upper end (high temperature end) of the rotating body-shaped member 40 can be, for example, (35-2 × D21) mm, and the inner diameter can be, for example, 30 mm. . Moreover, the axial length of the rotating body-shaped member 40 can be set to 200 mm, for example.

  In order to stably drive the second stage displacer 14 back and forth, the gap D21 is preferably 0.01 mm or more. And in order to prevent that refrigerant gas flows through gap D21, it is preferred that gap D21 is 0.03 mm or less.

  Further, in order for the refrigerant gas to sufficiently flow through the gap D22, the gap D22 is preferably 0.4 mm or more. In order to efficiently cool the second stage cylinder 12 when the refrigerant gas passes through the gap D22, the gap D22 is preferably 1.0 mm or less.

  Therefore, the difference between the high temperature end diameter R21 and the low temperature end diameter R22 in the second stage displacer 14 is preferably 0.74 mm or more and 1.98 mm or less.

  Further, a spiral groove may be formed on the outer peripheral surface of the rotating body-shaped member 40. Another example of the configuration of the second stage displacer 14 in the case where the spiral groove 47 is formed on the outer peripheral surface of the rotating body-shaped member 40 is shown in the schematic sectional view of FIG. 4 together with the second stage cylinder 12. .

  By forming the spiral groove 47, the refrigerant gas can be prevented from leaking through the gap D21 between the second stage displacer 14 and the second stage cylinder 12, and the refrigeration capacity of the GM refrigerator is increased. be able to.

  In addition, the rotary body-shaped member 40 may be formed by coating the surface of a cylindrical stainless steel tube with, for example, an abrasion-resistant resin made of cloth-containing phenol. As a result, as will be described later, the second stage cylinder 12 is disposed horizontally, and the outer surface of the second stage displacer 14 is brought to the inner surface of the second stage cylinder 12 by the weight of the second stage displacer 14. Even in the case of contact, wear of the second stage displacer 14 can be prevented.

  FIG. 5 is a cross-sectional view taken along line AA in FIG. However, in FIG. 5, the wire mesh 42 is not shown for easy illustration.

  As shown in FIGS. 3 and 5, a plurality of openings 46 b having the same diameter are provided at equal positions along the circumferential direction at the height of the wire mesh 42 on the outer peripheral surface of the rotating body-shaped member 40. It is preferable. And it is preferable that the low temperature end of the hollow space (refrigerant gas flow path) 24 is connected to the plurality of openings 46b. As shown in FIG. 5, for example, eight openings 46b can be provided at equal intervals along the circumferential direction.

  The plurality of openings 46b may not be provided at equal intervals along the circumferential direction. For example, when the plurality of openings 46b do not have the same diameter, the position where the openings 46b are provided along the circumferential direction is adjusted so that the amount of refrigerant gas flowing through the gap D22 is substantially uniform along the circumferential direction. can do.

  Here, with reference to FIG. 6 to FIG. 8, the effect that the GM refrigerator according to the present embodiment can prevent the outer peripheral surface of the second stage displacer 14 from wearing will be described in comparison with the comparative example.

  FIG. 6 is a cross-sectional view schematically showing how refrigerant gas is supplied to and discharged from the expansion space 22 when the second stage displacer 14 of the GM refrigerator according to the present embodiment is eccentric. FIG. 6A shows a state when the refrigerant gas is supplied to the expansion space 22, and FIG. 6B shows a state when the refrigerant gas is discharged from the expansion space 22. 7 and 8 are cross-sectional views schematically showing how refrigerant gas is supplied to or discharged from the expansion space 22 when the second-stage displacer 14 of the GM refrigerator according to the comparative example is eccentric. FIG. 7 shows a state when the refrigerant gas is supplied to the expansion space 22, and FIG. 8 shows a state when the refrigerant gas is discharged from the expansion space 22. 6 to 8, the flow of the refrigerant gas is indicated by an arrow.

  In the following description, it is assumed that the narrower gap when the second stage displacer 14 is eccentric is Dn and the wider gap is Dw. The positions of the high temperature end and the low temperature end of the second stage displacer 14 are X1 and X2, respectively. Further, the pressure at the high temperature end of the second stage displacer 14 is P1, and the pressure at the low temperature end (expansion space 22) of the second stage displacer 14 is P2.

  7 and 8, a sectional view is shown in the center, a pressure distribution graph in the gap Dn is shown above the sectional view shown in the center, and a pressure distribution in the gap Dw is lower than the sectional view shown in the center. A graph is shown.

  In the arrangements shown in FIGS. 6 to 8, the left end of the second stage cylinder 12 and the second stage displacer 14 is the high temperature end, and the right end is the low temperature end.

  Further, in FIG. 6 (the same applies to FIGS. 7 and 8), the illustration of the lid member 41 is omitted to simplify the illustration, and the second stage displacer 14 is moved from the high temperature end of the second stage displacer 14. It is shown as a monotonically decreasing diameter to the low temperature end. However, when the diameter monotonously decreases from the high temperature end of the rotating body-shaped member 40 to the low temperature end of the rotating body-shaped member 40, and the outer diameter does not change from the high temperature end of the lid member 41 to the low temperature end of the lid member 41. Even when the cover member 41 is omitted, the same effect is obtained in that the second stage displacer 14 is prevented from being worn.

  In the GM refrigerator according to the comparative example, the high temperature end of the hollow space (refrigerant gas flow path) 24 communicates with an opening 46 c formed on the end surface of the high temperature end of the second stage displacer 14. However, the low temperature end of the hollow space (refrigerant gas flow path) 24 does not communicate with the opening provided on the outer peripheral surface of the second stage displacer 14. As shown in FIGS. 7 and 8, the low temperature end of the hollow space (refrigerant gas flow path) 24 communicates with an opening 46 d provided on the end surface of the low temperature end of the second stage displacer 14.

  In the comparative example, when the refrigerant gas is supplied to the expansion space 22, most of the refrigerant gas is supplied through the hollow space (refrigerant gas flow path) 24, and a part of the refrigerant gas is supplied to the second stage displacer 14 and the second stage. It is supplied through gaps Dn and Dw with the cylinder 12.

  Most of the refrigerant gas is supplied from the high temperature side to the hollow space (refrigerant gas flow path) 24 through the opening 46c formed in the end surface at the high temperature end of the second stage displacer 14. The refrigerant gas supplied to the hollow space (refrigerant gas flow path) 24 is supplied to the expansion space 22 through the opening 46d formed in the end surface at the low temperature end of the second stage displacer 14.

  On the other hand, a part of the refrigerant gas is supplied to the gaps Dn and Dw from the high temperature side through between the high temperature end of the second stage displacer 14 and the second stage cylinder 12. The refrigerant gas supplied to the gaps Dn and Dw is supplied to the expansion space 22 through the space between the low temperature end of the second stage displacer 14 and the second stage cylinder 12.

  At this time, the pressure P1 at the high temperature end is higher than the pressure P2 at the low temperature end. Further, in both the gaps Dn and Dw, the cross-sectional area of the flow path increases along the direction in which the refrigerant gas flows. Accordingly, in both the gap Dn and the gap Dw, the pressure monotonously decreases (drops) from the pressure P1 at the high temperature end to the pressure P2 at the low temperature end.

  Further, as described above, the gap Dn is narrower than the gap Dw. Accordingly, the pressure drop in the narrower gap Dn is larger than the pressure drop in the wider gap Dw, and therefore the pressure distribution differs between the gap Dn and the gap Dw.

  In both the gap Dn and the gap Dw, the pressure is P1 at the high temperature end X1, and the pressure is P2 at the low temperature end X2. However, as shown in the pressure distribution graph in the gap Dn above the center sectional view of FIG. 7 and the pressure distribution graph in the gap Dw below the center sectional view of FIG. 7, the high temperature end X1 and the low temperature end X2 In the position X between the pressure Dw, the pressure Pw in the gap Dw is larger than the pressure Pn in the gap Dn. As a result, a force from the gap Dw toward the gap Dn acts on the second stage displacer 14 as shown in the cross-sectional view in the center of FIG. An eccentric force acts on the second stage displacer 14 that is eccentric with respect to the second stage cylinder 12 in a direction that increases the eccentricity. Such a phenomenon is called a hydraulic lock phenomenon.

  This hydraulic lock phenomenon may also occur when the second stage displacer 14 has the same diameter from the high temperature end to the low temperature end. Due to the dimensional tolerance of the inner diameter of the second stage cylinder 12, the dimensional tolerance of the outer diameter of the second stage displacer 14, etc., for example, the second stage displacer 14 may be slightly inclined with respect to the second stage cylinder 12. This is because an eccentric force may be generated.

  In the comparative example, when the refrigerant gas is discharged from the expansion space 22, most of the refrigerant gas is discharged through the hollow space (refrigerant gas flow path) 24 formed inside the second stage displacer 14. Is discharged through the gaps Dn and Dw between the second stage displacer 14 and the second stage cylinder 12.

  Most of the refrigerant gas is discharged from the expansion space 22 to the hollow space (refrigerant gas flow path) 24 through the opening 46d formed in the end surface at the low temperature end of the second stage displacer 14. The refrigerant gas discharged to the hollow space (refrigerant gas flow path) 24 is discharged to the high temperature side through the opening 46c formed in the end surface of the second stage displacer 14 at the high temperature end.

  On the other hand, a part of the refrigerant gas passes through between the low temperature end of the second stage displacer 14 and the second stage cylinder 12 from the expansion space 22 and is discharged into the gaps Dn and Dw. The refrigerant gas discharged into the gaps Dn and Dw passes between the high temperature end of the second stage displacer 14 and the second stage cylinder 12 and is discharged to the high temperature side.

  At this time, the pressure P2 on the low temperature side is higher than the pressure P1 on the high temperature side. Further, in both the gaps Dn and Dw, the cross-sectional area of the flow path decreases along the direction in which the refrigerant gas flows. Accordingly, in both the gap Dn and the gap Dw, the pressure monotonously decreases (drops) from the pressure P2 at the low temperature end to the pressure P1 at the high temperature end.

  Further, as described above, the gap Dn is narrower than the gap Dw. Accordingly, since the pressure drop in the narrower gap Dn is different from the pressure drop in the wider gap Dw, the pressure distribution is different between the gap Dn and the gap Dw.

  In both the gap Dn and the gap Dw, the pressure is P2 at the low temperature end X2, and the pressure is P1 at the high temperature end X1. However, as shown in the pressure distribution graph in the gap Dn above the center sectional view in FIG. 8 and the pressure distribution graph in the gap Dw below the center sectional view in FIG. 8, the low temperature end X2 and the high temperature end X1. In the position X between the pressure Dn and the pressure Pn in the gap Dn is larger than the pressure Pw in the gap Dw. As a result, a force from the gap Dn toward the gap Dw acts on the second stage displacer 14 as shown in the cross-sectional view in the center of FIG. A restoring force acts on the second stage displacer 14 that is eccentric with respect to the second stage cylinder 12 in a direction that prevents the eccentricity.

  As described above, in the comparative example, when the refrigerant gas is discharged from the expansion space 22, the restoring force acts in a direction to prevent the eccentricity of the second stage displacer 14, but when the refrigerant gas is supplied to the expansion space 22. The eccentric force acts in the direction of increasing the eccentricity of the second stage displacer 14. In the GM refrigerator, since the step of supplying the refrigerant gas to the expansion space 22 and the step of discharging the refrigerant gas from the expansion space 22 are repeated alternately, the restoring force cannot always be applied, and the second stage displacer 14 Will gradually become eccentric.

  If the second stage displacer 14 comes into contact with one inner peripheral surface of the second stage cylinder 12 due to the eccentric force, the eccentricity cannot be eliminated thereafter. Therefore, the same part of the second stage displacer 14 comes into contact with the inner peripheral surface of the second stage cylinder 12, and the second stage displacer 14 is worn.

  On the other hand, in the GM refrigerator according to the present embodiment, as shown in FIG. 6, the high temperature end of the hollow space (refrigerant gas flow path) 24 is an opening formed on the end surface of the high temperature end of the second stage displacer 14. It communicates with 46a. The low temperature end of the hollow space (refrigerant gas flow path) 24 communicates with an opening 46 b provided on the outer peripheral surface of the second stage displacer 14.

  Also in the present embodiment, when supplying the refrigerant gas to the expansion space 22, most of the refrigerant gas is supplied through the hollow space (refrigerant gas flow path) 24, and a part thereof is connected to the second stage displacer 14 and the second stage displacer 14. It is supplied through gaps Dn and Dw with the second-stage cylinder 12.

  Most of the refrigerant gas is supplied from the high temperature side to the hollow space (refrigerant gas flow path) 24 through the opening 46a formed on the end surface of the second stage displacer 14 at the high temperature end. The refrigerant gas supplied to the hollow space (refrigerant gas flow path) 24 is ejected into the gaps Dn and Dw through the opening 46b formed in the outer peripheral surface of the second stage displacer 14. The refrigerant gas ejected into the gaps Dn and Dw is supplied to the expansion space 22 through the space between the low temperature end of the second stage displacer 14 and the second stage cylinder 12.

  The refrigerant gas ejected into the gaps Dn and Dw has the same effect as, for example, a static pressure bearing.

  On the other hand, a part of the refrigerant gas is supplied to the gaps Dn and Dw from the high temperature side through between the high temperature end of the second stage displacer 14 and the second stage cylinder 12. The refrigerant gas supplied to the gaps Dn and Dw is supplied to the expansion space 22 through the space between the low temperature end of the second stage displacer 14 and the second stage cylinder 12.

  Also in the present embodiment, the eccentricity of the second stage displacer 14 is increased by the refrigerant gas supplied between the high temperature end of the second stage displacer 14 and the second stage cylinder 12 to the gaps Dn and Dw. There is an eccentric force acting in the direction of However, in the present embodiment, the effect of the static pressure bearing by the refrigerant gas ejected into the gaps Dn and Dw from the opening 46b formed on the outer peripheral surface of the second stage displacer 14 is greater. Therefore, in the present embodiment, the eccentricity of the second stage displacer 14 can be prevented, and the contact of the second stage displacer 14 with the second stage cylinder 12 can be prevented.

  On the other hand, also in the present embodiment, when the refrigerant gas is discharged from the expansion space 22, most of the refrigerant gas is discharged through the hollow space (refrigerant gas flow path) 24, and a part thereof is the second stage displacer 14. And the second-stage cylinder 12 through the gaps Dn and Dw.

  Most of the refrigerant gas passes through the space between the low temperature end of the second stage displacer 14 and the second stage cylinder 12 from the expansion space 22 and is discharged into the gaps Dn and Dw. The refrigerant gas discharged into the gaps Dn and Dw is discharged into the hollow space (refrigerant gas flow path) 24 through the opening 46b formed in the outer peripheral surface of the second stage displacer 14. The refrigerant gas discharged to the hollow space (refrigerant gas flow path) 24 is discharged to the high temperature side through the opening 46a formed on the end surface of the second stage displacer 14 at the high temperature end.

  On the other hand, a part of the refrigerant gas passes through between the low temperature end of the second stage displacer 14 and the second stage cylinder 12 from the expansion space 22 and is discharged into the gaps Dn and Dw. The refrigerant gas discharged into the gaps Dn and Dw passes between the high temperature end of the second stage displacer 14 and the second stage cylinder 12 and is discharged to the high temperature side.

  At this time, the pressure P2 on the low temperature side is higher than the pressure P1 on the high temperature side. Further, in both the gaps Dn and Dw, the cross-sectional area of the flow path decreases along the direction in which the refrigerant gas flows. Accordingly, in both the gap Dn and the gap Dw, the pressure monotonously drops from the pressure P2 at the low temperature end to the pressure P1 at the high temperature end. Further, as described above, the gap Dn is narrower than the gap Dw. Therefore, as in the comparative example, a force from the gap Dn toward the gap Dw acts on the second stage displacer 14. That is, a restoring force acts on the second stage displacer 14 in a direction to prevent the eccentricity.

  As described above, in the present embodiment, when the refrigerant gas is supplied to the expansion space 22 and when the refrigerant gas is discharged from the expansion space 22, force is exerted in a direction to prevent the eccentricity of the second stage displacer 14. Works. In the GM refrigerator, since the process of supplying the refrigerant gas to the expansion space 22 and the process of discharging the refrigerant gas from the expansion space 22 are repeated alternately, a force always acts in a direction to prevent the eccentricity of the second stage displacer 14. Can be made.

  As a result, even if the second stage displacer 14 comes into contact with one inner peripheral surface, the eccentricity can be eliminated thereafter. Therefore, it is possible to prevent the same part of the second stage displacer 14 from coming into contact with the inner peripheral surface of the second stage cylinder 12 and wear the second stage displacer 14.

Furthermore, no opening is formed in the end surface of the second stage displacer 14 at the low temperature end, and the opening in which the low temperature end of the hollow space (refrigerant gas flow path) 24 is formed in the outer peripheral surface of the second stage displacer 14. When the refrigerant gas is discharged from the expansion space 22 through the hollow space (refrigerant gas flow path) 24, the cooled refrigerant gas is transferred to the inner peripheral surface of the second stage cylinder 12 by communicating with 46b. Therefore, the second stage cylinder 12 can be efficiently cooled, and the cooling capacity of the GM refrigerator can be improved.
(Modification of the first embodiment)
Next, with reference to FIG. 9, the GM refrigerator which concerns on the modification of 1st Embodiment is demonstrated. In the GM refrigerator according to this modification, the diameter of the rotating body-shaped member 40a of the second stage displacer 14a decreases in a stepped manner from the high temperature end to the position where the opening 46b is provided.

  The GM refrigerator according to this modification is the same as the GM refrigerator according to the first embodiment except for the rotating body-shaped member 40a. Therefore, in this modification, description about parts other than the rotary body-shaped member 40a is omitted.

  FIG. 9 is a schematic cross-sectional view showing the configuration of the second stage displacer 14 a together with the second stage cylinder 12 in the GM refrigerator according to this modification.

  In the arrangement shown in FIG. 9, the upper ends of the second stage cylinder 12 and the second stage displacer 14a are high temperature ends, and the lower ends are low temperature ends.

  The rotating body-shaped member 40a has a rotating body shape with the upper and lower ends opened, as in the first embodiment. The configurations of the lid member 41, the wire mesh 42, the felt plug 43, the cold storage material 18, the felt plug 44, and the punching metal 45 are the same as those in the first embodiment.

  In addition, an opening 46b that forms a refrigerant gas flow path is provided at the height of the metal mesh 42 on the outer peripheral surface of the rotating body-shaped member 40a. The low temperature end of the hollow space (refrigerant gas flow path) 24 communicates with the opening 46b.

  In this modification, the diameter of the rotating body-shaped member 40a decreases in a stepped manner from the high temperature end to the position where the opening 46b is provided. As shown in FIG. 9, for example, the diameter can be reduced in three steps.

  Also in this modified example, the second stage displacer 14a has the low temperature end diameter R22 smaller than the high temperature end diameter R21. This prevents the second stage displacer 14a from coming into contact with the inner peripheral surface of the second stage cylinder 12 when supplying and discharging the refrigerant gas to and from the expansion space 22, and wear of the second stage displacer 14a. Can be prevented.

In addition, the spiral groove may be formed in the outer peripheral surface of the rotary body-shaped member 40a. By forming the spiral groove, the refrigerant gas can be prevented from leaking through the gap D21 between the second stage displacer 14a and the second stage cylinder 12, and the refrigeration capacity can be increased.
(Second Embodiment)
Next, with reference to FIG. 10, the GM refrigerator which concerns on 2nd Embodiment is demonstrated. In the GM refrigerator according to the present embodiment, in the first stage displacer 13a, the diameter of the low temperature end is smaller than the diameter of the high temperature end, and the low temperature end of the refrigerant gas flow path is the outer peripheral surface of the first stage displacer 13a. It communicates with the opening 34 provided in the.

  The GM refrigerator according to the present embodiment can be configured in the same manner as the GM refrigerator according to the first embodiment, except for the rotating body-shaped member 30a of the first stage displacer 13a. Therefore, in the present embodiment, description of portions other than the rotating body-shaped member 30a is omitted.

  FIG. 10 is a schematic cross-sectional view showing the configuration of the first stage displacer 13a together with the first stage cylinder 11 in the GM refrigerator according to the present embodiment.

  In the arrangement shown in FIG. 10, the upper ends of the first stage cylinder 11 and the first stage displacer 13a are the high temperature ends, and the lower ends are the low temperature ends.

  The rotating body-shaped member 30a has a rotating body shape with the upper and lower ends open, as in the first embodiment. The configurations of the flange 31, the opening 32, the cold storage material 17, and the lid member 33 are the same as those in the first embodiment.

  Moreover, the opening 34 for forming a refrigerant gas flow path is formed in the outer peripheral surface of the rotary body-shaped member 30a at the height at which the lower metal mesh of the regenerator material 17 is disposed. The opening 34 communicates with the low temperature end of the hollow space (refrigerant gas flow path) 23.

  In the first stage displacer 13a, the diameter R12 at the low temperature end is smaller than the diameter R11 at the high temperature end. That is, the diameter R12 at the lower end of the lid member 33 (the low temperature end of the first stage displacer 13a) is smaller than the diameter R11 of the high temperature end of the rotating body-shaped member 30a. As a result, when the refrigerant gas is supplied to and discharged from the expansion space 21, the first stage displacer 13a has the inner peripheral surface of the first stage cylinder 11 by the same function and effect as those of the first embodiment. Can be prevented, and wear of the first stage displacer 13a can be prevented.

  Note that the lid member 33 may have a cylindrical shape with the upper end (high temperature end) diameter equal to the lower end (low temperature end) diameter R12, and may further have a lower end (low temperature end) of the rotating member 30a. The diameter may be equal to the diameter R12 of the lower end (low temperature end) of the lid member 33. In this case, the diameter R12 of the lower end (low temperature end) of the rotating body shaped member 30a is smaller than the diameter R11 of the upper end (high temperature end) of the rotating body shaped member 30a.

  Furthermore, the diameter of the first stage displacer 13a may monotonously decrease from the upper end (high temperature end) of the rotating body-shaped member 30a to the lower end (low temperature end) of the rotating body-shaped member 30a. That is, the diameter of the first stage displacer 13a may monotonously decrease from the upper end (high temperature end) of the rotating body-shaped member 30a to the position where the opening 34 is provided. Thereby, the flow of the refrigerant gas when the first stage displacer 13a reciprocates becomes smoother, and the effect of preventing the wear of the first stage displacer 13a can be improved.

  The clearance between the outer peripheral surface of the upper end (high temperature end) of the first stage displacer 13a and the inner peripheral surface of the first stage cylinder 11 is D11, and the outer peripheral surface of the lower end (low temperature end) of the first stage displacer 13a. And a clearance between the inner circumferential surface of the first stage cylinder 11 and D12. At this time, the gap D12 can be made larger than the gap D11 by making the diameter R12 of the low temperature end of the first stage displacer 13a smaller than the diameter R11 of the high temperature end of the first stage displacer 13a.

  Moreover, as shown in FIG. 10, the helical groove may be formed in the outer peripheral surface of the rotary body-shaped member 30a. By forming the spiral groove, the refrigerant gas can be prevented from leaking through the gap D11 between the first stage displacer 13a and the first stage cylinder 11, and the refrigeration capacity of the GM refrigerator can be increased. Can do.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to such specific embodiments, and various modifications can be made within the scope of the gist of the present invention described in the claims. Can be modified or changed.

DESCRIPTION OF SYMBOLS 10 Compressor 11 1st stage cylinder 12 2nd stage cylinders 13 and 13a 1st stage displacer 14 and 14a 2nd stage displacer 15 Crank mechanism 16 Refrigerant gas flow path 17 and 18 Cool storage material 19 and 20 Heat station 21 , 22 Expansion space 23, 24 Hollow space (refrigerant gas flow path)
30, 40 Rotating body-shaped member 31 Flange 32, 34, 46a, 46b, 48 Opening 33, 41 Lid member 35, 47 Spiral groove 42 Wire mesh

Claims (3)

A cylinder,
A refrigerant gas flow path provided in the cylinder so as to be capable of reciprocating along the cylinder, forming an expansion space at one end of the cylinder, and supplying and discharging a refrigerant gas into the expansion space inside. A rotating body-shaped displacer,
A regenerator that is housed in the refrigerant gas flow path and stores cold energy generated by expanding the refrigerant gas supplied to the expansion space when the displacer reciprocates along the cylinder. And
The displacer has a low temperature end diameter smaller than a high temperature end diameter,
A regenerator type refrigerator having a low temperature end of the refrigerant gas flow path communicating with an opening provided on an outer peripheral surface of the displacer.   The cold storage according to claim 1, wherein the low-temperature end of the refrigerant gas flow path communicates with a plurality of openings having the same diameter provided on the outer peripheral surface of the displacer at equal intervals along the circumferential direction. Refrigerator.   The regenerator type refrigerator according to claim 1 or 2, wherein the displacer has a monotonically decreasing diameter from the high temperature end to a position where the opening is provided.

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