JP2004239206A - Compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piston vibration compressor used for a cryogenic refrigerator having a reduced external diameter size and improved processing and dimensional accuracy of a cylinder. <P>SOLUTION: A cylindrical outer yoke 8 is coaxially coupled to a disc member 21 having a working gas flow path 5. The outer yoke 8 thereby forms a peripheral wall of a pressure vessel 14. An inner yoke 6 is incorporated inside the outer yoke 8. Since the outer yoke 8 serves also as the peripheral wall of the pressure vessel 14, it is not necessary to separately engage the peripheral wall with the outer part of the outer yoke 8, which reduces the external diameter of the compressor and the number of parts. Further, in a double-action compressor having a pair of pistons 4, 4, placed opposite to each other, a cylinder 1 is divided for each of the pistons 4 and 4 by the disc member 21. Such a constitution enables reduction of the longitudinal size of the cylinder 1 and makes it easy to increase the processing accuracy. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a piston-type compressor that generates a cryogenic temperature by supplying an oscillating flow of a working gas to an expansion section of a refrigerator.
[0002]
[Prior art]
The compressor is described in, for example, Patent Document 1, and FIG. 3 is a vertical cross-sectional view showing a compressor having the same configuration as that of the compressor. The illustrated compressor is of a double-acting type in which a pair of pistons move in opposition to each other, and is inserted through a cylinder 1 forming a cylindrical space and a gap 2 forming a clearance seal in the cylinder 1, and a working gas is introduced into the cylindrical space. A pair of left and right pistons 4 forming a compression space 3 of the above, a working gas flow path 5 for guiding a working gas in the compression space 3 to an expansion portion outside the machine, and a left and right inner yoke 6 arranged on the outer peripheral side of the cylinder 1 And an outer yoke 8 which is combined with the outer peripheral side thereof to form an annular gap 7 with each inner yoke 6, and is attached to each inner yoke 6 with the illustrated polarity to form a magnetic field in the gap 7. Left and right annular permanent magnets 9, driver coils 11 arranged in the gap 7 and connected to the respective pistons 4 via coil bobbins 10, and supports for supporting the respective driver coils 11 and the piston 4 in a reciprocating manner. Spring 12 and gap And a pressure vessel 14 to form a gas chamber 13 which communicates with the compression space 3 through 2. The gas chamber 13 is filled with a working gas (generally helium gas).
[0003]
The cylinder 1 is integral with a pair of pistons 4, and a compression space 3 is formed between opposing surfaces of the pistons 4 inserted from both ends. The pressure vessel 14 includes a cylindrical casing 15 forming a peripheral wall thereof, and an end plate 16 closing both ends thereof. The casing 15 is fitted on the outer peripheral surface of the outer yoke 8. The other end of the support spring 12 whose one end is connected to the coil bobbin 10 is connected to an end plate 16 of the pressure vessel 14 via a support member 17. The working gas flow path 5 is formed by a pipe 18 that passes through the housing 15 of the pressure vessel 14 and reaches the cylinder 1. The magnetic passage of the permanent magnet 9 is formed by the inner yoke 6 and the outer yoke 8, and the magnetic lines of force from the N pole of the permanent magnet 9 return to the S pole around the gap 7, the outer yoke 8, and the inner yoke 6. , A magnetic field is formed in the gap 7. Therefore, when alternating currents having phases different from each other by 180 ° are applied to the left and right driver coils 11, the pistons 4 and 4 reciprocate in opposite directions due to an electromagnetic force generated between the alternating current and the magnetic field of the permanent magnet 9. An oscillating flow is generated in the working gas in the compression space 3.
[0004]
[Patent Document 1]
JP-A-11-159902 [0005]
[Problems to be solved by the invention]
Since the conventional compressor has the housing 15 of the pressure vessel 14 on the outer peripheral portion of the outer yoke 8, the outer diameter is increased accordingly. Further, in the illustrated double-acting compressor, the cylinder 1 is configured integrally with the pair of pistons 4 and 4 on the left and right sides, so that the longitudinal dimension is larger than the opening diameter, and it is difficult to increase the processing accuracy. Was.
An object of the present invention is to reduce the outer diameter of a compressor and improve the workability and dimensional accuracy of a cylinder.
[0006]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a cylinder that forms a cylindrical space, a piston that is inserted into the cylinder through a gap, and that forms a compression space for working gas in the cylindrical space, A working gas flow path that guides the working gas out of the machine, an inner yoke arranged on the outer peripheral side of the cylinder, and an outer circumferential side of the inner yoke combined with the inner yoke to form an annular gap between the inner yoke. An outer yoke to be formed, a permanent magnet for forming a magnetic field in the gap, a driver coil disposed in the gap and connected to the piston via a coil bobbin, and a reciprocating motion between the driver coil and the piston. In a compressor provided with a support spring that supports the compression gas and a pressure vessel that forms a gas chamber that communicates with the compression space through the gap, a disk member having the working gas flow path is provided. The peripheral wall of the pressure vessel is formed by coupling the Kisotogawa yoke coaxially, which is incorporated the inner yoke therein.
[0007]
According to the first aspect, since the outer yoke also serves as the peripheral wall of the pressure vessel, it is not necessary to separately fit this peripheral wall to the outer peripheral portion of the outer yoke, and the outer diameter of the compressor is reduced accordingly, The number of parts is also reduced. Further, in the double-acting compressor, since the cylinder is divided into pistons by the disk member, the longitudinal dimension of the cylinder is reduced, and the processing accuracy in the axial direction is easily increased.
[0008]
According to the first aspect, it is preferable that the inner yoke is provided with a slit extending radially from a center (claim 2). Thereby, the eddy current generated in the inner yoke by the alternating current flowing through the driver coil can be suppressed.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. Note that the same reference numerals are used for the portions corresponding to the conventional example. Here, FIG. 1 is a longitudinal sectional view showing an embodiment of a double-acting compressor, and FIG. 2 is a transverse sectional view of an inner yoke along a line II-II in FIG. In FIG. 1, reference numeral 21 denotes a disk member made of a non-magnetic material, for example, stainless steel. Bosses 21a are integrally formed on both sides of the center of a circular plate constituting the disk member 21, and are formed on both end surfaces of the boss 21a. A dish-shaped recess is formed, and a through hole 22 is formed at the center. The working gas flow path 5 formed of a round hole is formed in the radial direction so as to reach the outer peripheral surface from the through hole 22.
[0010]
A cylindrical outer yoke 8 made of a magnetic material such as iron is coaxially connected to both left and right surfaces of the disk member 21 in FIG. 1 by friction welding or the like. The outer yoke 8 also serves as a peripheral wall of the pressure vessel 14 forming the gas chamber 13 in which the working gas is sealed. The inside yoke 6 is incorporated inside the outside yoke 8. The inner yoke 6 is a cylindrical body with a brim made of a magnetic material. After the cylinder 1 made of a cylindrical body with a brim made of stainless steel is fitted into the hollow portion, it is inserted into the outer yoke 8 until it hits the disk member 21. It is tightened by a screw (not shown) screwed into the disk member 21 through the flange 6a. In this state, the inner yoke 6 is fitted to the outer yoke 8 on the outer peripheral surface of the collar 6a, the cylinder 1 is fitted to the boss 21a of the disk member 21, and the collar 1a is connected to the inner yoke 6 and the disk. It is sandwiched and fixed between the member 21. Here, as shown in FIG. 1 and FIG. 2, a slit 6 b radially extending from the center is radially formed in the inner yoke 6. The annular permanent magnet 9 is fitted to the outer yoke 8 and forms a magnetic field in the gap 7 between the inner yoke 6 and the outer yoke 8.
[0011]
The piston 4 is formed by closing the tip of a stainless steel tube. The piston 4 is provided with a coil bobbin 10 around which a driver coil 11 is wound, a first support spring 23 made of a disc-shaped leaf spring, and an inner and outer 2 made of stainless steel. The heavy interval tubes 24 and 25 and the second support spring 26 are sequentially fitted and fastened by a ring nut 27 to form a movable portion. This movable portion is inserted with the piston 4 into the cylinder 1 and combined with the outer yoke 8 as shown in the figure, and is fixed by screws (not shown) penetrating the outer peripheral portions of the support springs 23 and 26 and the outer spacing tube 25. In this state, the compression space 3 is formed between the opposing surfaces of the pair of pistons 4 and 4 with the through hole 22 of the disk member 21 interposed therebetween, and the driver coil 11 is located in the gap 7 and The axial positions match. An end plate 16 is fixed to the open end of the outer yoke 8 by welding, and the pressure vessel 14 is sealed.
[0012]
The operation of the compressor shown in FIG. 1 is substantially the same as that of the conventional example. When an AC having a phase difference of 180 ° is supplied from a power supply terminal (not shown) to the left and right driver coils 11 via the lead wires 28, the AC The piston 4 is reciprocated to the right and left in FIG. 1 in opposite directions by the electromagnetic force received in the magnetic field of the permanent magnet 9, and generates an oscillating flow in the working gas in the compression space 3 communicating with the gas chamber 13 through the gap 2. Let it. This oscillating flow is guided to an expansion section of a cryogenic refrigerator (not shown) via the working gas flow path 5 and generates a cryogenic temperature at a low temperature end.
[0013]
In the illustrated embodiment, the outer yoke 8 is also used as a peripheral wall of the pressure vessel 14. Therefore, a pressure vessel housing that is separately fitted to the outer peripheral portion of the outer yoke 8 is not required, and the outer diameter of the compressor is reduced and the number of components is reduced accordingly. Also, in the illustrated double-acting compressor, the cylinder 1 can be divided into right and left parts by the disc member 21 as a boundary. The accuracy is improved. On the other hand, an eddy current in the circumferential direction is generated in the inner yoke 6 in a direction to cancel the magnetic flux of the driver coil 11, but in the illustrated embodiment, a large number of eddy currents are formed in the inner yoke 6 in a direction orthogonal to the eddy current (in the illustrated case). Since 16 slits 6b are formed, the current path is cut off, and generation of eddy current is suppressed.
[0014]
In the illustrated embodiment, an example of a double-acting compressor is shown. However, the present invention is also applicable to a single-acting compressor in which the cylinder 1 and the piston 4 are provided only on one of the left and right sides of the disk member 21. In that case, one end of the through hole 22 of the disk member 21 may be closed, and the disk member 21 may be used also as one end plate of the pressure vessel 14.
[0015]
【The invention's effect】
As described above, according to the present invention, the outer yoke is also used as the peripheral wall of the pressure vessel, so that the outer diameter of the compressor is reduced to reduce the size of the compressor, and the number of parts is reduced, thereby reducing the manufacturing cost. Is cheaper. In particular, in a double-acting compressor, the longitudinal dimension of the cylinder is shortened, and the processing accuracy is improved. Further, by forming a slit in the inner yoke, generation of eddy current can be suppressed, and power consumption of the compressor can be reduced.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a compressor showing an embodiment of the present invention.
FIG. 2 is a cross-sectional view of the inner yoke taken along the line II-II in FIG.
FIG. 3 is a longitudinal sectional view of a compressor showing a conventional example.
[Explanation of symbols]
Reference Signs List 1 cylinder 2 gap 3 compression space 4 piston 5 working gas flow path 6 inner yoke 6b slit 7 gap 8 outer yoke 9 permanent magnet 10 coil bobbin 11 driver coil 13 gas chamber 14 pressure vessel 21 disk members 23, 26 support spring

Claims (2)

A cylinder that forms a cylindrical space, a piston that is inserted into the cylinder via a gap, and forms a compression space for a working gas in the cylindrical space, and a working gas flow path that guides the working gas in the compression space out of the machine. An inner yoke arranged on the outer peripheral side of the cylinder; an outer yoke combined with the outer peripheral side of the inner yoke to form an annular gap with the inner yoke; and applying a magnetic field to the gap. A permanent magnet to be formed, a driver coil arranged in the gap and connected to the piston via a coil bobbin, a support spring for supporting the driver coil and the piston in a reciprocating manner, and via the gap A pressure vessel forming a gas chamber communicating with the compression space,
A disk member having the working gas flow path formed therein is provided, a peripheral wall of the pressure vessel is formed by coaxially coupling the outer yoke to the disk member, and the inner yoke is incorporated inside the pressure vessel. And the compressor. 2. The compressor according to claim 1, wherein a slit is formed in the inner yoke in a radial direction from a center.

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