JP2007205607A - Gm refrigerating machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To alleviate a load to a driving means reciprocating a displacer with respect to a GM (Gifford-McMahon) refrigerating machine having the driving means for reciprocating the displacer. <P>SOLUTION: In this GM refrigerating machine having cylinders of first and second stages 12A, 12B, displacers 13A, 13B of first and second stages disposed in each of the cylinders 12A, 12B so as to be reciprocative a displacer driving means for reciprocating the displacers 13A, 13B in the cylinders 12A, 12B, a compressor 7 for allowing a refrigerant gas of high and low pressure to flow in and out to the cylinders 12A, 12B, and valves V1, V2 controlling the timing for supplying and discharging the refrigerant gas to the cylinders 12A, 12B, a linear motor 20 is used as the displacer driving means. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a GM refrigerator, and more particularly to a GM refrigerator having a driving means for reciprocating a displacer.

  In general, Gifford McMahon refrigerator (GM refrigerator) controls the gas flow path from the compressor that compresses refrigerant gas such as helium gas using a valve, and expands helium gas in the expansion space in the cylinder. Get cold. In addition, a displacer is provided inside the cylinder. The displacer is provided with a cold storage material that discharges the refrigerant gas and enhances the cooling efficiency. The displacer is configured to reciprocate in a cylinder, and the displacer is generally driven by a motor.

  Therefore, a drive conversion mechanism that converts the rotation of the motor into the reciprocating motion of the displacer is required. In general, a scotch yoke mechanism is used in the GM refrigerator as this drive conversion mechanism (see Patent Document 1). FIG. 1 shows a conventional GM refrigerator 100, and FIG. 2 shows an enlarged Scotch yoke mechanism 109 used in the GM refrigerator 100. As shown in FIG. The scotch yoke mechanism 109 is generally constituted by a crank member 107 and a scotch yoke 108.

  The crank member 107 is fixed to a rotation shaft of the motor 106 (hereinafter referred to as a drive rotation shaft 124). The crank member 107 has a configuration in which a crank pin 125 is provided at a position eccentric from the mounting position of the drive rotating shaft 124. Therefore, when the crank member 107 is attached to the drive rotary shaft 124, the drive rotary shaft 124 and the crank pin 125 are in an eccentric state.

  The scotch yoke 108 includes a yoke plate 126, a vertical shaft 127, a roller bearing 128, and the like. The scotch yoke 108 is configured to reciprocate in the direction of arrows Z1 and Z2 in the figure within the housing 104. A vertical shaft 127 is disposed at the central vertical position of the yoke plate 126 so as to extend in the vertical direction (Z1, Z2 direction).

  The yoke plate 126 is formed with a horizontally long window 134 extending in the directions of arrows X1 and X2 in the figure, and a roller bearing 128 is disposed in the horizontally long window 134. The roller bearing 128 is configured to be able to roll in the directions of arrows X1 and X2 within the horizontally elongated window 134. A crank pin engaging hole 133 that engages with the crank pin 125 is formed at the center position of the roller bearing 128.

  Accordingly, when the drive rotation shaft 124 rotates with the crank pin 125 engaged with the roller bearing 128, the crank pin 125 rotates so as to draw an arc, whereby the Scotch yoke 108 reciprocates in the directions of arrows Z1 and Z2. Moving. At this time, the roller bearing 128 reciprocates in the horizontal window 134 in the directions of arrows X1 and X2.

A vertical shaft 127 disposed at the lower portion of the scotch yoke 108 is connected to a displacer 110 in which cool storage materials 115 and 116 are provided. Accordingly, when the scotch yoke 108 reciprocates in the directions of arrows Z1 and Z2 in the figure, the displacer 110 also reciprocates in the directions of arrows Z1 and Z2 within the cylinder 105, and a cooling process is performed accordingly.
JP-A-6-300378

  However, conventionally, the rotational force of the motor 106 needs to be converted into a linear motion using the Scotch yoke mechanism 109 in order to cause the displacer 110 to linearly reciprocate in the directions of arrows X1 and X2 in the drawing. Therefore, the motor 106 rotates the crank member 107, and the crank pin 125 of the crank member 107 rotates the roller bearing 128, whereby the vertical shaft 127 moves in the directions of arrows X1 and X2 in the figure.

  Thus, in the conventional GM refrigerator 100, a large load (resistance force) is applied to the motor 106 in order to convert the rotational force of the motor 106 into the linear reciprocating motion of the vertical axis 127 (ie, the displacer 110). As a result, there is a problem that the motor 106 is stepped out. Further, the scotch yoke mechanism 109 requires a large number of parts, resulting in unsatisfactory assembly and increased product cost.

  This invention is made | formed in view of said point, and it aims at providing the GM refrigerator which can reduce the load with respect to the drive means which reciprocates a displacer.

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

The invention described in claim 1
A cylinder,
A displacer disposed in a reciprocating manner in the cylinder;
Displacer driving means for reciprocating the displacer in the cylinder;
A compressor for flowing high and low pressure refrigerant gas into and out of the cylinder;
In a GM refrigerator having a valve for controlling the timing of supplying and exhausting the refrigerant gas to the cylinder,
As the displacer driving means, a linear motor is used.

  According to the invention, the displacer driving means for reciprocating the displacer in the cylinder is a linear motor, so that, unlike the displacer driving means using a conventional rotary motor, the rotational motion is converted into a linear motion. Therefore, the load (resistance) on the displacer driving means can be reduced. As a result, it is possible to prevent motor step-out that has occurred in the past, and to reduce the number of times of maintenance for correcting step-out.

  ADVANTAGE OF THE INVENTION According to this invention, the step-out of the motor which generate | occur | produced conventionally can be prevented, and the frequency | count of a maintenance for correcting step-out can be reduced.

  Next, the best mode for carrying out the present invention will be described with reference to the drawings.

  FIG. 3 shows a GM refrigerator 1 according to an embodiment of the present invention. The GM refrigerator 1 generally includes a housing 4, first and second stage cylinders 12A and 12B, first and second stage displacers 13A and 13B23, regenerators 14A and 14B, a linear motor 20, And a gas supply device 5 and the like.

The gas supply device 5 includes a compressor 7 and supply / exhaust flights V1, V2. The compressor 7 compresses the refrigerant gas (helium gas) to 20 tens Kg / cm ² . The intake valve V <b> 1 is opened, and the exhaust valve V <b> 2 is connected to a connection hole 26 formed in the housing 4 via the gas flow path 8. The connection hole 26 is connected to the first stage cylinder 12 </ b> A via the communication path 28. Therefore, the high-pressure refrigerant gas is supplied into the first-stage cylinder 12A by opening the intake valve V1 and closing the exhaust valve V2.

  The housing 4 is provided with a first stage cylinder 12 </ b> A at the bottom thereof. Inside the first stage cylinder 12A, a first stage displacer 13A is disposed so as to be capable of reciprocating in the directions of arrows Z1 and Z2 in the figure.

  A cool storage material 14A is disposed inside the first stage displacer 13A. Further, a gas flow hole 18A is formed in the upper part of the first stage displacer 13A in the figure, and a gas flow hole 19A is provided in the lower part. Therefore, the refrigerant gas that has flowed into the first stage displacer 13A from the gas supply device 5 passes through the gas flow holes 18A and 19A, and between the first stage displacer 13A and the first stage displacer 13B. Is supplied to the first stage expansion chamber 11A.

  The first stage displacer 13A and the first stage displacer 13B are joined using a universal joint (not shown). In FIG. 3, for the sake of convenience of illustration, the displacers 13A and 13B are integrated. Show.

  The second stage displacer 13B is disposed inside the second stage cylinder 12B so as to be capable of reciprocating in the directions of arrows Z1 and Z2 in the figure. A cool storage material 14B is disposed inside the second stage displacer 13B. Further, a gas flow hole 18B is formed in the upper part of the second stage displacer 13B in the drawing, and a gas flow hole 19B is formed in the lower part.

  Therefore, the refrigerant gas supplied from the gas supply device 5 reaches the first stage expansion chamber 11A via the gas flow hole 18A, the cold storage material 14A, and the gas flow hole 19A, and further, the gas flow hole 18B and the cold storage material 14B. Then, it flows into the second stage expansion chamber 11B through the gas flow hole 19B.

  In addition, a linear motor 20 (displacer driving means) is disposed above the first stage displacer 13A. Specifically, a magnet rod 22 constituting the linear motor 20 is connected to the upper part of the first stage displacer 13A. When the linear motor 20 is driven, the first stage displacer 13A and the second stage displacer 13B reciprocate in the directions of arrows Z1 and Z2 in the drawing.

  Next, the linear motor 20 will be described. The linear motor 20 includes a coil member 21 that is a stator and a magnet rod 22 that is a mover.

  The coil member 21 is fixed to the housing 4. The coil member 21 includes a coil holding member 23 and a plurality of coils 24 formed in an annular groove formed in the coil holding member 23. The coil member 21 may be formed of a resin, or may be formed of a metal having excellent thermal conductivity in order to improve heat dissipation characteristics. The plurality of coils 24 are provided to face the magnet rod 22 and are arranged in parallel in the Z1 and Z2 directions. Each coil 24 is connected to a controller that controls driving of the linear motor 20 (not shown).

  On the other hand, the lower end (X2 direction end portion) of the magnet rod 22 is connected to the first stage displacer 13A, and thus the first stage displacer 13A is configured to move integrally with the magnet rod 22. ing. Further, the upper and lower portions of the magnet rod 22 are supported by a guide member 25 provided in the housing 4, so that the magnet rod 22 is configured to move accurately and stably in the directions of arrows Z1 and Z2. .

  Further, as shown in FIG. 4, a permanent magnet having a plurality of N poles and S poles is formed on the magnet rod 22 so that the N poles or the S poles face each other. Are arranged with their directions reversed alternately. That is, the magnet rod 22 has a configuration in which N-pole magnetic poles and S-pole magnetic poles are alternately arranged along the directions of arrows Z1 and Z2.

  Next, the operation of the linear motor 20 will be described. Each coil 24 has a coil group including three coils of U, V, and W phases. The coils 24 of any phase are configured to face and separate from the outer peripheral surface of the linear motor 20. The arrangement pitch of the coils 24 in the Z1 and Z2 directions is set to be shorter than the arrangement pitch of the permanent magnets formed in the linear motor 20.

  The controller described above is configured to calculate an optimum current corresponding to the positional relationship between the coils 24 and the permanent magnets formed on the linear motor 20 and to pass the current through the coils 24. As a result, due to the interaction between the current flowing through each coil 24 and the magnetic flux formed by the permanent magnet formed on the magnet rod 22, an attractive force and a repulsive force are generated between the coil 24 and the permanent magnet, As a result, the magnet rod 22 moves in the Z1 and Z2 directions with respect to the coil member 21.

  As described above, the linear motor 20 can reciprocate the displacers 13A and 13 in the directions of the arrows Z1 and Z2 with a simple configuration including the coil member 21 and the magnet rod 22. Therefore, the number of parts can be reduced as compared with the GM refrigerator 100 (see FIG. 1) using the conventional scotch yoke mechanism 109, and the cost and size of the GM refrigerator 1 can be reduced. .

  Next, the operation of the GM refrigerator 1 configured as described above will be described.

  The gas supply device 5 is configured to open the intake valve V1 and close the exhaust valve V2 while the first display displacer 13A, 13B is located at the bottom dead center. Thus, the high-pressure refrigerant gas generated by the compressor 7 is supplied into the first and second stage cylinders 12A and 12B via the gas flow path 8, the connection hole 26, and the communication path 28.

  In this state, the linear motor 20 is driven to move the first and second stage displacers 13A and 13B upward, and then the intake valve V1 is closed and the exhaust valve V2 is opened. Thereby, the refrigerant gas in the first and second stage expansion chambers 11A and 11B expands, thereby generating cold.

  Next, the linear motor 20 is driven, the first and second stage displacers 13A and 13B are moved downward, and the gas supply device 5 collects the refrigerant gas expanded in the cylinders 12A and 12B. By repeating the above cycle, the first stage expansion chamber 11A can generate a cold of about 40K, and the second stage expansion chamber 11B can generate a cryogenic temperature of 20K or less.

  In order to generate cold in the expansion chambers 11A and 11B as described above, it is necessary to reciprocate the displacers 13A and 13B by the linear motor 20, but the linear motor 20 is connected to the first stage displacer 13A. The magnet rod 22 is directly moved directly.

  For this reason, unlike the conventional configuration in which the rotational motion of the motor 106 is converted into the linear motion of the displacer 110 using the Scotch yoke mechanism 109 (see FIGS. 1 and 2), it is not necessary to convert the rotational motion into linear motion. Therefore, the load (resistance) on the linear motor 20 can be reduced as compared with the conventional case. Thereby, it is possible to prevent the step-out from occurring in the linear motor 20, and thus it is possible to reduce the number of times of maintenance for correcting the step-out.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. For example, the present invention can be applied not only to the GM type refrigerator but also to a refrigerator using a Stirling refrigerator or other regenerator.

  In each of the above-described embodiments, the example in which the present invention is applied to the two-stage GM refrigerator 1 has been described. However, the application of the present invention is not limited to the two-stage refrigerator, It can also be applied as a part of a multi-stage refrigerator having a three or more stage. It will be apparent to those skilled in the art that other various modifications, improvements, combinations, and the like can be made.

FIG. 1 is a cross-sectional view of a conventional GM refrigerator. FIG. 2 is an enlarged perspective view showing a scotch yoke mechanism provided in a conventional GM refrigerator. FIG. 3 is a cross-sectional view of a GM refrigerator that is an embodiment of the present invention. FIG. 4 is an enlarged perspective view showing a linear motor provided in the GM refrigerator as one embodiment of the present invention.

Explanation of symbols

1 GM refrigerator 5 Gas supply device 7 Compressor 8 Gas flow path 11A First stage expansion chamber 11B Second stage expansion chamber 12A First stage cylinder 12B Second stage cylinder 13A First stage displacer 13B Second Stage displacer 14A, 14B Cold storage material 20 Linear motor 21 Coil member 22 Magnet rod 24 Coil 24

Claims (1)

A cylinder,
A displacer disposed in a reciprocating manner in the cylinder;
Displacer driving means for reciprocating the displacer in the cylinder;
A compressor for flowing high and low pressure refrigerant gas into and out of the cylinder;
In a GM refrigerator having a valve for controlling the timing of supplying and exhausting the refrigerant gas to the cylinder,
A GM refrigerator using a linear motor as the displacer driving means.

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