JP3393071B2 - Gas compressor and cold head - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas compressor and a cold head, and more particularly to a gas compressor suitable for use as a cooling machine and a cold head connected to the gas compressor.

[0002]

2. Description of the Related Art FIG. 3 shows a basic structure of a Stirling cooler. The Stirling cooler includes a gas compressor 101, a cold head 102, and a distribution duct 103 connecting these components.
Have. The gas compressor 101 includes a cylinder 106 and a piston 107 that reciprocates in the cylinder, and defines a compression chamber 108 between the cylinder 106 and the piston 107.

The cold head 102 has a cylinder 109.
And a displacer 111 disposed therein for reciprocal movement. The displacer 111 is a cylinder 10
9 is elastically supported by a spring or the like so as to be movable in the axial direction. An expansion space 116 is defined between one end of the cylinder 109 and the displacer 111, and a compression space 117 communicating with the flow duct 103 is defined between the other end of the cylinder 109 and the displacer 111.

Inside the displacer 111, a gas flow path 112 for connecting the compression space 117 and the expansion space 116 to each other.
Is provided. The gas flow passage 112 is filled with the cool storage material, and the refrigerant gas flowing in the gas flow passage 112 exchanges heat with the cool storage material. The piston 107 and the displacer 111 are reciprocally moved with their phases being shifted, and a reverse Stirling cycle is executed.

The reverse Stirling cycle consists of four steps of isothermal compression of refrigerant gas, isothermal transfer, isothermal expansion and isochoric transfer. The reverse Stirling cycle will be briefly described below.

Initially, displacer 111 is assumed to be in a neutral position by a spring. When the piston 107 moves to the right side in the drawing, the refrigerant gas is isothermally compressed in the compression chamber 108 and flows into the compression space 117 of the cold head 102 through the flow duct 103. At this time, due to the fluid resistance of the gas channel 112 filled with the cold storage material, the displacer 1
11 moves to the expansion space 116 side. That is, expansion space 1
The operating pressure of the entire system reaches a maximum as the space volume of 16 decreases. The process up to this state is isothermal compression.

When the piston 107 reaches the right end,
Since there is no gas flow, the compression chamber 108 and the expansion space 116
The pressure between and balances. Since the fluid resistance does not work, the displacer 111 returns to its original neutral position due to the restoring force of the spring. At this time, the compressed gas is compressed by the compression chamber 10.
Go to 8. This process is isovolumetric transfer.

When the moving direction of the piston 107 is reversed and the piston 107 moves to the left, the displacer 111 also moves to the left almost simultaneously due to the fluid resistance force acting on the displacer 111. At this time, the space volume of the expansion space 116 increases, and the refrigerant gas expands. This process is isothermal expansion. In order to expand at an isothermal temperature, it is necessary to absorb heat from the outside, so coldness occurs.

At the time when the piston 107 reaches the maximum point at the left end, the fluid resistance does not work, so the displacer 1
11 is returned to the neutral position by the spring. The gas in the expansion space 116 is transferred in the same volume. That is, the cooled gas in the expansion space 116 passes through the gas flow path 112 and the compression space 117.
Return to. In addition, each process of an actual cooler does not operate in a completely isothermal state as described here.

In such a Stirling cooler, since the expansion space 116 serves as a cold source, the object to be cooled is arranged in thermal connection with the expansion space 116. For example,
An infrared imaging device is arranged at the right end of the cold head 102.

FIG. 4 shows a sectional view of a conventional gas compressor.
The pistons 107a and 107b are arranged to face each other, and the shaft 1
It is driven by 31a and 131b. Shaft 131a, 1
Movable coils 124a and 124b are coupled to 31b, and permanent magnets 121a and 121b and a yoke 122 are coupled.
It is inserted in the gap of the magnetic circuit formed by a and 122b.

The shafts 131a and 131b are leaf springs 132a and 1a made of a disk-shaped thin elastic metal diaphragm.
It is supported by the outer case by 33a and 132b, 133b. These leaf springs 132 and 133 elastically allow the movement of the shafts 131a and 131b in the movement axis direction. The current supplied to the movable coils 124a and 124b is
It is supplied via the lead wires 125a and 125b.

Such disc-shaped leaf springs 132, 133
By utilizing the above, it becomes possible to support the piston 107 on the movement axis with high accuracy and prohibit the displacement in the direction orthogonal to the movement axis. Therefore, it is possible to adopt a clearance seal system that gives a narrow gap between the piston and the cylinder and reduces the amount of gas leakage as much as possible. By adopting the clearance seal method, it is possible to prevent wear of the piston and the displacer.

[0014]

In order to support the piston with a disc-shaped leaf spring and increase the stroke of the piston, it is necessary to increase the diameter of the leaf spring. For this reason,
The size of the gas compressor becomes large. It is difficult to increase the stroke of the piston without increasing the size of the gas compressor.

An object of the present invention is to provide a gas compressor capable of increasing the stroke of the piston without increasing the size.

Another object of the present invention is to provide a cold head capable of increasing the stroke of the displacer without increasing the size.

[0017]

According to one aspect of the present invention, a cylinder having a cylindrical inner peripheral surface and a piston arranged in the cylinder and having an outer peripheral surface aligned with the inner peripheral surface of the cylinder. And fixed to the piston,
A piston rod thinner than a ton, the outer peripheral surface of the piston faces the inner peripheral surface of the cylinder with a minute gap,
And the piston is movable in the axial direction of the cylinder .
Thus, there is provided a gas compressor having a bearing for supporting the piston rod , and a reciprocating drive means for reciprocating the piston and the piston rod in the axial direction.

According to another aspect of the present invention, a cylinder having a cylindrical inner peripheral surface, one end of which is closed, and an outer surface which is attached to the other end of the cylinder and defines a closed space together with the cylinder. A displacer having a frame and an outer peripheral surface arranged in the cylinder and aligned with an inner peripheral surface of the cylinder, the expansion frame defining an expansion space between one end of the cylinder and the displacer, and the outer frame and the outer frame. A displacer that defines a compression space between the displacer and a gas flow passage that connects the expansion space and the compression space in the displacer; and the displacer is disposed in the gas flow passage. a cold accumulating material performs gas heat exchange flowing, the
It is fixed to the displacer and guided to the outside of the cylinder.
And a shaft with a smaller diameter than the displacer,
The outer peripheral surface of the serial displacer disposed oppositely across the inner circumferential surface with a small gap between the cylinder and such that the displacer is movable in the axial direction of the cylinder, supporting said shaft
There is provided a cold head having a bearing to be held and a refrigerant gas supply path communicating with the compression space and introducing and discharging a refrigerant gas.

Since the piston and the displacer are supported by the bearing, a large stroke can be secured as compared with the case where they are supported by the leaf spring. Also,
Since the piston and the cylinder and the displacer and the cylinder are sealed with a minute gap, it is possible to prevent performance deterioration due to wear.

[0020]

1 is a sectional view of a Stirling cooler according to an embodiment of the present invention. The Stirling cooler according to the embodiment includes a gas compressor 1, a cold head 50,
And a capillary tube 45 that connects the two.

The gas compressor 1 has a plane-symmetric structure with the partition wall 2 in between. Cylinders 3 are arranged on both sides of the partition wall 2. The cylinder 3 has a columnar inner peripheral surface, and is arranged such that its central axis is perpendicular to the partition wall 2. A piston 4 is arranged in the internal cavity of the cylinder 3. The piston 4 has an outer peripheral surface that matches the inner peripheral surface of the cylinder 3. A compression chamber 5 is defined by the piston 4, the cylinder 3, and the partition wall 2. The compression chamber 5 communicates with the capillary tube 45 via the gas flow path 6 formed in the partition wall 2.

A piston rod 8 is connected to the end of the piston 4 opposite to the compression chamber 5. The piston rod 8 extends along an extension line of the central axis of the cylinder 3. The piston rod 8 is supported by the bearings 10 and 11.
It is supported so as to be movable in the axial direction and prohibited from moving in the direction orthogonal to the axis. The bearings 10 and 11 are fixed to the cylinder 3 via bearing support members 13 and 14, respectively.

The piston 4 is held by the bearings 10 and 11 so that a minute gap is formed between the inner peripheral surface of the cylinder 3 and the outer peripheral surface of the piston 4. If this gap is about 10 μm or less, it acts as a clearance seal.

A cylindrical gap 16 is formed in the cylinder 3 so as to surround the inner peripheral surface thereof from the end surface opposite to the partition wall 2 toward the partition wall 2. A permanent magnet 17 is attached on the outer peripheral surface of the gap 16. The cylinder 3 also serves as a yoke, and the permanent magnet 17, the cylinder 3 and the gap 16 define a magnetic circuit.

An electromagnetic coil 20 is inserted in the gap 16 so as to interlink with the magnetic circuit. The electromagnetic coil 20 includes a piston rod 8 via a coil support member 21.
It is fixed to.

Current leads 23 and 2 are attached to the electromagnetic coil 20.
Current is supplied via 4. Current leads 23 and 24
Is configured to include a coil spring that connects between the bearing support member 14 fixed to the cylinder 3 and the coil support member 21 fixed to the piston rod 8. Coil spring 23
And 24 are elastically deformed in the axial direction of the piston rod 8. As the coil springs forming the current leads 23 and 24, those in which the reciprocating motion of the movable part such as the piston 4 resonates with the operating frequency are adopted.

The space in which the piston 4, bearings 10 and 11, current leads 23 and 24, etc. are arranged is sealed by an outer case 30.

The cold head 50 comprises a cylinder 51, a displacer (piston) 52, a coil spring 53, and an outer frame 57. The cylinder 51 has a columnar inner surface, for example, a cylindrical surface. One end of the cylinder 51 is closed and the other end is closed by an outer frame 57. A displacer 52 is inserted in the internal cavity of the cylinder 51. A seal member 54 is arranged between the outer peripheral surface of the displacer 52 and the inner peripheral surface of the cylinder 51.

The cylinder 51 and the displacer 52 define an expansion space 55 at the left end of the cylinder 51 in the drawing, and the displacer 52 and the outer frame 57 define a compression space 56 at the right end of the drawing. In the displacer 52,
Gas channel 5 that connects the expansion space 55 and the compression space 56
8 are provided. The gas flow path 58 is filled with a regenerator material 59 such as copper wire mesh and lead balls.

The displacer 52 is elastically supported in the axial direction by a coil spring 53 arranged in the compression space 56. The compression space 56 communicates with the compression chamber 5 of the gas compressor 1 via the capillary tube 45 and the gas flow path 6.

When an alternating current having a predetermined frequency is applied to the electromagnetic coil 20, the piston 4 reciprocates against the elastic force of the current leads 23 and 24. Two pistons 4 on both sides of the partition wall 2
Control the phase of the alternating current so that they move in opposite directions. When the two pistons 4 move toward each other, the pressure inside the compression chamber 5 becomes high, and when both pistons move away from each other, the pressure inside the compression chamber 5 becomes low. By repeating the reciprocating motion of the piston 4, the gas pressure can be changed periodically.

By repeatedly supplying and discharging the refrigerant gas to and from the cold head 50, the reverse Stirling cycle can be executed and cold can be generated in the expansion space 55.

The bearings 10 and 11 support the piston 4 in the cylinder 3 with a predetermined clearance. Therefore, it is possible to prevent abrasion due to partial contact of the piston 4 with the inner peripheral surface of the cylinder 3, and to improve reliability. In addition, a large stroke can be secured as compared with the case where the piston 4 is supported by the leaf spring. Also,
Bearings do not experience fatigue failure as do leaf springs. By increasing the stroke of the piston 4,
The performance of the Stirling cooler can be improved.

It is preferable to use vacuum grease for the bearings 10 and 11 of the above embodiment. By using the vacuum grease, it is possible to prevent the refrigerant gas from being contaminated.

As the bearing used in the above embodiment, for example, a linear bearing such as a linear ball bearing LB type manufactured by NSK can be used. A slide bearing may be used instead of the linear bearing.

In the above embodiment, the case where the radial position of the displacer 52 is fixed by the seal member 54 has been described. The displacer 52 is also the piston 4 of the gas compressor 1.
Similarly, the bearing may be supported by the bearing.

FIG. 2 is a sectional view of a cold head in which a displacer is supported by bearings. A displacer 62 is inserted into a cylindrical cylinder 61 whose low temperature end is closed and whose high temperature end is opened. A minute gap is defined between the inner peripheral surface of the cylinder 61 and the outer peripheral surface of the displacer 62. A part of the high temperature portion 62 a of the displacer 62 projects from the opening of the cylinder 61. A shaft 63 having a smaller diameter than the outer peripheral surface of the displacer 62 extends from the end surface of the high temperature portion 62a along the central axis.

The opening at the high temperature end of the cylinder 61 is formed in a flange shape, and the cylindrical support member 6 is formed on the end surface of the flange.
7 is attached. The support member 67 is arranged so as to surround the high temperature portion 62 a of the displacer 62 and the shaft 63. The side surface of the support member 67 has an opening 67.
a is provided, and the inner and outer spaces communicate with each other through the opening 67a. The first bearing 64 is attached to the end surface of the flange at the high temperature end of the cylinder 61, and the second bearing 65 is attached to the tip of the support member 67 via the bearing support member 66. The first bearing 64 and the second bearing 65 respectively support the high temperature portion 62a of the displacer 62 and the shaft 63 so as to prohibit radial movement.

A coil spring 68 is attached between the end of the high temperature portion 62a of the displacer 62 and the tip of the bearing support member 66. The coil spring 68 elastically supports the displacer 62 in the axial direction.

An outer frame 70 is attached to the outermost peripheral portion of the end surface of the flange at the high temperature end of the cylinder 61. The joint between the two is kept airtight by an O-ring. The outer frame 70 defines an airtight compression space 69 that houses the high temperature portion 62 a of the displacer 62, the shaft 63, the support member 67, the bearings 64 and 65, and the coil spring 68.

A compression space 69 communicates with the compression chamber 5 of the gas compressor 1 shown in FIG. 1, for example, via a capillary tube 71 attached to the outer frame 70.

Displacer 62 bearings 64 and 65
Supported by the inner surface of the cylinder 61 and the displacer 62.
Since the seal member is not arranged between the outer peripheral surface and the outer peripheral surface, it is possible to prevent performance deterioration due to wear of the seal member.

The present invention has been described above with reference to the embodiments.
The present invention is not limited to these. For example, it will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

[0044]

As described above, according to the present invention,
A large stroke can be secured by supporting the piston or displacer in the cylinder with a bearing. Since the clearance can be sealed between the inner peripheral surface of the cylinder and the outer peripheral surface of the piston, it is possible to avoid performance deterioration due to wear of the seal member.

[Brief description of drawings]

FIG. 1 is a sectional view of a Stirling cooler using a gas compressor according to an embodiment of the present invention.

FIG. 2 is a sectional view of a cold head of a Stirling cooler according to an embodiment of the present invention.

FIG. 3 is a schematic diagram showing a basic configuration of a Stirling cooler.

FIG. 4 is a sectional view of a conventional gas cycle engine.

[Explanation of symbols]

1 gas compressor 2 partitions 3 cylinders 4 pistons 5 compression chamber 6 gas flow paths 8 piston rod 10, 11, 64, 65 bearings 13, 14 Bearing holding member 16 gap 17 permanent magnet 20 electromagnetic coil 21 Coil holding member 23, 24 current lead 30 outer case 45,71 Capillary tube 50 cold heads 51, 61 cylinders 52,62 Displacer 53, 68 coil spring 54 Seal member 55 Expansion space 56,69 Compressed space 58 gas flow path 59 Cold storage material 63 shaft 66 Bearing support member 67 Support member 70 outer frame

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Claims (5)

(57) [Claims] 1. A cylinder having a cylindrical inner peripheral surface, a piston arranged in the cylinder and having an outer peripheral surface aligned with the inner peripheral surface of the cylinder, and fixed to the piston, and more than the piston. Thin fixie
And Nroddo, the outer peripheral surface of the piston is disposed oppositely across the inner circumferential surface with a small gap between the cylinder and as the piston is movable in the axial direction of the cylinder, to support the piston rod
That bearing and, the piston and the piston rod, a gas compressor and a reciprocating drive means for reciprocating in the axial direction. 2. The bearing is a linear bearing or
The gas compressor according to claim 1, which is a sliding bearing. 3. A cylinder having a cylindrical inner peripheral surface, one end of which is closed, an outer frame which is attached to the other end of the cylinder and which defines a closed space together with the cylinder, and inside the cylinder. A displacer that is disposed and has an outer peripheral surface that matches the inner peripheral surface of the cylinder, the expander defining an expansion space between one end of the cylinder and the displacer, and a compression space between the outer frame and the displacer. And a displacer in which a gas flow path that connects the expansion space and the compression space is provided in the displacer, and heat is exchanged with the gas that is disposed in the gas flow path and that flows in the gas flow path. The regenerator material to be used and the outside of the cylinder that is fixed to the displacer.
A shaft with a smaller diameter than the displacer
When the outer peripheral surface of the displacer disposed oppositely across the inner circumferential surface with a small gap between the cylinder and such that the displacer is movable in the axial direction of said cylinder, said shaft
A cold head having a bearing for supporting and a refrigerant gas supply path communicating with the compression space for introducing and discharging a refrigerant gas. 4. The cold head according to claim 3 , further comprising an elastic member that elastically supports the displacer in the axial direction of the cylinder. 5. The bearing is a linear bearing or
The cold according to claim 3 or 4, which is a sliding bearing.
head.