JP2006029255A - Vibration compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the accuracy of clearance seal in a vibration compressor provided with a clearance seal between a cylinder and a piston. <P>SOLUTION: In a vibration compressor including a cylinder 4 and a piston 6 inserted in the cylinder 4 via a gap 7 forming the clearance seal and forming a compression space 8 for working gas in the cylinder 4, the cylinder 4 is fitted to a yoke 1, and a support spring 12 reciprocatably supporting the piston 6 in a cantilever style is fastened on an end surface of the yoke 1. Aligning accuracy of the cylinder 5 and the piston 6 can be easily maintained and accuracy of the clearance seal 7 is improved by fastening the support spring 12 supporting the piston 6 to the yoke 1 having the cylinder 4 fitted. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

    The present invention relates to a piston-type vibration compressor that supplies an oscillating flow of working gas to a cryogenic refrigerator such as a pulse tube refrigerator.

As the vibration compressor, a piston inserted into a cylinder through a gap forming a clearance seal is cantilevered by a support spring so as to be able to reciprocate in the axial direction. There is one that reciprocates by a linear drive unit to compress the working gas in the compression space formed in the cylinder. A linear drive part is arrange | positioned in the annular space formed of a yoke. The compression heat of the working gas is transmitted from the working gas in the gas chamber communicating with the working gas compression space to the casing through the clearance seal, and is radiated from the casing made of a material having high thermal conductivity to the outside air. This type of vibration compressor is described in Patent Document 1, for example.
JP 2002-13475 A

  The above-described vibration compressor in which a clearance seal is provided between the cylinder and the piston has an advantage that the piston does not come into contact with the cylinder and therefore wear and heat generation do not occur. However, in order to take advantage of this advantage, it is necessary to strictly control the dimensional accuracy of the clearance seal, and higher centering accuracy is required as compared with the structure in which the piston is slidably guided by the cylinder.

  In that case, in the vibration compressor of Patent Document 1, since the yoke that supports the piston is fastened to the casing that also serves as the cylinder via the support spring, the piston and the support spring, the support spring and the yoke, The assembly accuracy between the yoke and the housing is integrated, and the centering accuracy between the piston and the cylinder is difficult to achieve. In addition, high thermal conductivity materials such as aluminum and copper are usually used for the housing because of heat dissipation requirements, but these materials have a large coefficient of thermal expansion, and clearance seals are generated by the thermal expansion of the housing due to compression heat. There is a problem that is easy to change.

  SUMMARY OF THE INVENTION An object of the present invention is to easily improve the accuracy of a clearance seal and improve heat dissipation in a vibration compressor in which a clearance seal is provided between a cylinder and a piston.

  In order to solve the above problems, a vibration compressor according to the present invention includes a double cylindrical yoke having an annular space open at one end, a cylinder fitted into the yoke, and a clearance seal formed on the cylinder. A piston that forms a compressed space for the working gas in the cylinder, a casing disposed around the yoke, and an axial direction connected to the piston and in the annular space of the yoke A mover coil movably inserted into the yoke, an annular permanent magnet that is fitted in the yoke and applies a magnetic field to the drive coil, and is fastened to the end face of the yoke to allow the piston to reciprocate in the axial direction. A support spring that is cantilever-supported and a cover that is joined to the end face of the casing and forms a gas chamber that communicates with the casing through the gap together with the casing, and an alternating current is supplied to the driver coil. When flowed, the piston is reciprocated to compress the working gas in the gas chamber in the compression space, and the compressed gas is supplied to an external device through a gas flow path formed in the housing. (Claim 1).

  According to the first aspect of the present invention, the cylinder is fitted into the yoke, and the support spring for supporting the piston is fastened to the yoke. Get higher.

  In the invention of claim 1, the yoke, the piston and the cylinder are preferably made of the same material or materials having similar thermal expansion coefficients (invention 2). Thereby, the thermal expansion of the piston and the cylinder due to the compression heat of the working gas becomes substantially the same, and the change in the clearance seal becomes small.

  In the first aspect of the present invention, the pair of pistons may be provided to face each other, and the compression space may be formed therebetween. In this case, the cylinders of the pair of pistons may be configured integrally ( Claim 3). As a result, the variation in the clearance seal between the opposing pistons is reduced, the number of parts requiring high accuracy is reduced, and the assembly accuracy is increased.

  In the first aspect of the present invention, a number of axial grooves may be provided on the inner peripheral surface of the casing that contacts the working gas. Thereby, the contact area of a housing | casing and the working gas in a gas chamber can be increased, and heat dissipation can be improved. In this case, a cylindrical body having a large number of axial grooves on the inner peripheral surface may be fitted inside the casing (Claim 5).

  In the invention of claim 1, a cylindrical joint is inserted between the casing and the cover, the joint and the casing are joined by friction welding or friction stir welding, and the joint and the cover are joined together. It is good to join by welding (Claim 6). Although aluminum or copper having high thermal conductivity is preferably used for the casing and stainless steel having good workability is preferably used for the cover, it is difficult to directly weld aluminum or copper and stainless steel. Therefore, a cylindrical joint made of stainless steel or the like with good weldability between the cover and the cover is inserted between the casing and the cover, and the joint is joined to the casing by friction welding or friction stir welding. After assembling the built-in parts, the cover should be joined to the joint by welding.

  According to the present invention, a high-precision clearance seal is obtained between the cylinder and the piston, and wear and heat generation due to contact of the piston with the cylinder are surely avoided and high compression efficiency is obtained. Further, the heat dissipation of heat generated by the compression heat of the working gas and the copper loss of the driver coil is improved by increasing the contact area between the housing and the working gas.

  Embodiments of the present invention will be described below with reference to FIGS.

  FIG. 1 is a longitudinal sectional view of a vibration compressor showing Embodiment 1 of the present invention. Since the illustrated vibration compressor is a reciprocating compressor in which a pair of opposed pistons reciprocate in opposite directions, one of the left and right symmetrical portions will be described. In FIG. 1, reference numeral 1 denotes a pair of left and right yokes, which are formed in a double cylindrical shape having an annular space 2 with one end opened in a hollow cylindrical body. The yoke 1 is formed with a large number of radially cut grooves for suppressing the generation of eddy currents. Reference numeral 3 denotes a left and right integral housing disposed around the yoke 1, which is formed in a vertical cross-sectional shape having a partition wall 3a at the left and right centers of the hollow cylindrical body, and the yoke 1 is concentrically accommodated in the left and right spaces. It has been. In the center hole of the yoke 1 and the housing 3, a left and right integrated cylinder 4 is fitted via an annular packing (O-ring) 5, whereby the concentricity of the yoke 1 and the housing 3 is maintained.

  A pair of left and right pistons 6 are inserted into the cylinder 4 so as to oppose each other through a gap 7 that forms a clearance seal, and a working gas compression space 8 is formed between the pistons 6 and 6. The compression space 8 communicates with the gas flow path 3 b formed in the radial direction in the partition wall 3 a of the housing 3 through the hole 4 a of the cylinder 4. In the annular space 2 of the yoke 1, a driver coil 9 is movably inserted in the axial direction, and this driver coil 9 is wound around a bobbin 10 fixed to the piston 6. An annular permanent magnet 11 is fitted inside the annular space 2 in the yoke 1 so as to surround the driver coil 9 via a gap. The permanent magnet 11 and the driver coil 9 constitute a linear drive unit that reciprocally drives the piston 6 as will be described later.

  The piston 6 is supported by a pair of front and rear circular support springs 12 so as to be capable of reciprocating in the axial direction, and the support springs 12 are fixed to the end face of the yoke 1 by bolts 13. The front and rear support springs 12 are spaced from each other by a spacing tube 14 and are fastened to the piston 6 by a ring nut 15. On the other hand, a cover 17 is joined to the end surface of the housing 3 via a cylindrical joint 16, and the cover 17 together with the housing 3 and the joint 16 is a sealed gas chamber 18 that leads to the compression space 8 via the gap 7. Is forming. An alternating current is passed through the driver coil 9 from the terminal 19 through the lead wire 20.

  Here, the yoke 1, the cylinder 4 and the piston 6 are made of the same material or materials having similar thermal expansion coefficients, for example, electromagnetic stainless steel (SUS403, 430, etc.). The cylinder 4 and the piston 6 may be made of nonmagnetic stainless steel (SUS304, 316 or the like) or titanium. On the other hand, the casing 3 is made of aluminum or copper having high thermal conductivity. For the joint 16 and the cover 17, stainless steel having good workability is suitable. In that case, it is generally difficult to directly weld the housing 3 (aluminum or copper), which is a different metal, and the joint 16 or the cover 17 (stainless steel). Therefore, the housing 3 and the joint 16 are joined to each other by friction welding or friction stir welding (FSW) before assembly of the vibration compressor. The cover 17 is joined to the joint 16 by beam welding or the like at the end of the assembly of the vibration compressor. In addition, you may use all mild steel as another material of the yoke 1, the cylinder 4, and the piston 6. FIG.

  In such a vibration compressor, the magnetic flux emitted from the N pole (outer peripheral side) of the permanent magnet 11 passes through the yoke 1 and passes through the annular space 2 in which the driver coil 9 is inserted into the S pole (inner peripheral side). Return. When an AC exciting current having a phase difference of 180 degrees is passed through the left and right driver coils 9 arranged in the magnetic circuit, the electromagnetic force acting between the magnetic field generated by the permanent magnet 11 and the coil current is Each piston 6 reciprocates in the axial direction opposite to each other to compress the working gas in the compression space 8. The compressed gas is supplied to an external device such as a pulse tube refrigerator (not shown) through the hole 4a and the gas flow path 3b. The heat generated by the compression of the working gas, the copper loss of the driver coil 9, etc. is transferred to the housing 3 through the working gas and radiated from the outer surface of the housing 3 to the atmosphere.

  According to the illustrated embodiment 1, the cylinder 4 is fitted into the yoke 1 and the support spring 12 that supports the piston 6 is directly fastened to the yoke 1 so that assembly errors are less accumulated. . Therefore, concentricity between the cylinder 4 and the piston 6 is easily obtained, and the accuracy of the gap (clearance seal) 7 is increased. Further, since the same material is used for the yoke 1, the cylinder 4 and the piston 6, the thermal expansion of each is equal, and the yoke 1, the cylinder 4, Changes in the clearance seal 7 due to the piston 6 being heated are also kept small. Further, since the cylinder 4 is integrally formed with the pair of pistons 6 and 6, the variation of the clearance seal 7 between the opposed pistons is reduced, and in addition, the number of parts requiring high accuracy is reduced and the assembly is reduced. Increases accuracy.

  On the other hand, a cylindrical joint 16 is inserted between the housing 3 and the cover 17. The joint 16 and the housing 3 are joined by friction welding or friction stir welding. Since they are joined by welding, the casing 3 and the cover 17 made of a different material can be easily and reliably joined, and a strong pressure vessel free from gas leakage is formed.

  FIG. 2 is a longitudinal sectional view of the vibration compressor showing the second embodiment, and FIG. 3 is a transverse sectional view of the casing in FIG. The second embodiment is different from the first embodiment in that a large number of axial grooves 21 are provided on the inner peripheral surface of the housing 3 that contacts the working gas. The heat generated by the compression of the working gas or the copper loss of the driver coil 9 is transmitted to the housing 3 through the working gas in the gas chamber 18, conducts heat inside the housing 3, and then flows from the outer surface to the atmosphere. Is dissipated. Therefore, as shown in FIG. 3, if a large number of axial grooves 21 are provided on the inner peripheral surface of the housing 3, the contact area with the working gas is increased and heat dissipation is improved. As shown in FIG. 3, it is advantageous in terms of thermal conductivity that the groove 21 is directly formed in the housing 3, but a commercially available circular tube 22 having the groove 21 is formed in the housing as shown in FIG. If it fits in the inner peripheral surface of 3, manufacture will become easy.

  In the illustrated embodiment, an example of a double-action vibration compressor in which a pair of opposed pistons reciprocate with a phase difference of 180 degrees is shown. However, the present invention is directed to a vibration compressor having a single piston. Is applicable.

BRIEF DESCRIPTION OF THE DRAWINGS It is a longitudinal cross-sectional view of the vibration compressor which shows Example 1 of this invention. It is a longitudinal cross-sectional view of the vibration compressor which shows Example 2 of this invention. It is a cross-sectional view of the housing | casing in FIG. It is a cross-sectional view which shows the different embodiment of the housing | casing in FIG.

Explanation of symbols

1 yoke 2 annular space 3 housing 4 cylinder 6 piston 7 clearance (clearance seal)
8 Compression space 9 Driver coil 11 Permanent magnet 12 Support spring 16 Joint 17 Cover 21 Strip groove 22 Circular pipe

Claims (6)

  A double-cylindrical yoke having an annular space open at one end, a cylinder fitted into the yoke, and a gap forming a clearance seal in the cylinder are inserted into the cylinder to compress the working gas. A piston that forms a space; a housing that is disposed around the yoke; a driver coil that is coupled to the piston and is movably inserted axially into the annular space of the yoke; and the yoke Joined to the end face of the housing, an annular permanent magnet that is fitted and applies a magnetic field to the driver coil, a support spring that is fastened to the end face of the yoke and cantileverably supports the piston in a reciprocating manner in the axial direction. And a cover that forms a gas chamber that communicates with the compression space through the gap together with the casing. When an alternating current is passed through the driver coil, the piston is reciprocated to reciprocate the gas. The working gas chamber is compressed by the compression space, the vibration compressor and supplying the compressed gas to the external device through the gas passage formed in the housing.   2. The vibration compressor according to claim 1, wherein the yoke, the piston, and the cylinder are made of the same material or materials having similar thermal expansion coefficients.   2. The vibration compressor according to claim 1, wherein the pair of pistons are provided to face each other, the compression space is formed therebetween, and the cylinders of the pair of pistons are integrally configured.   The vibration compressor according to claim 1, wherein a plurality of axial grooves are provided on an inner peripheral surface of the casing that contacts the working gas.   5. The vibration compressor according to claim 4, wherein a cylindrical body having a plurality of axial grooves on an inner peripheral surface is fitted inside the casing. A cylindrical joint is inserted between the casing and the cover, the joint and the casing are joined by friction welding or friction stir welding, and the joint and the cover are joined by welding. The vibration compressor according to claim 1.

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