JPH08152213A - Gas compressor and expansion device - Google Patents

Abstract

PURPOSE: To provide a gas compressor and expansion device having a long service life by keeping pressing force of a piston ring against a cylinder constant to prevent the piston ring from being abnormally worn. CONSTITUTION: In a gas compressor/expansion device, pistons 13, 16 are respectively provided with hollow interior portions, and openings are provided in faces of the pistons 13, 16 in reciprocating directions and check valves 40, 41 are arranged in the openings so as to keep the interior of the pistons at a high pressure. Piston rings 36, 37 are installed around cylindrical peripheries of the pistons 13, 16 in a freely movable state, and the piston rings 36, 37 are pressed against the cylinder 12, 15 side by gas pressure within the interior of the pistons.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas compression / expansion device for compressing or expanding a gaseous refrigerant by a piston that reciprocates in a cylinder.

[0002]

2. Description of the Related Art In recent years, there has been an urgent need to develop cryogenic storage technology for various samples and various materials in the fields of advanced technology such as biotechnology and electronic devices. In particular, a gas compression / expansion device such as a Stirling refrigerating device is attracting attention as a means for realizing the above-mentioned cryogenic temperature, and is being widely used for various infrared sensors, freezers for cooling superconducting devices and the like, biomedical freezer, freezer, etc. .

In such a gas compressor / expander,
An important issue is how to reduce friction and wear between the cylinder and the piston to keep the compression or expansion space airtight.

Therefore, conventionally, as shown in FIG. 5, a piston ring 52 is provided on the cylindrical peripheral surface of the piston 51, and a backup is provided between the piston 51 and the piston ring 52 to press the piston ring 52 against the cylinder 53. A ring 54 is provided to improve the airtightness of the compression or expansion space and prevent wear of the cylinder or piston.

[0005]

However, in the above-mentioned conventional device, when the piston 51 is partially pushed against the cylinder 53 due to the axial runout of the piston rod 55, the force with which the piston ring 52 is pressed against the cylinder 53 is reduced. The piston ring 52 does not become uniform on the cylindrical peripheral surface of the piston 51, and the piston ring 52 abnormally wears at a place where a pressing force is strong. Due to the wear, the airtightness of the compression or expansion space is secured and the wear of the cylinder or the piston is prevented. However, there is a problem that the life of the gas compression / expansion device is shortened.

The present invention has been made in view of the above circumstances, and a gas compression / expansion machine having a long life by keeping the pressing force of the piston ring against the cylinder constant and preventing abnormal wear of the piston ring. It is provided.

[0007]

According to the present invention, in a gas compression / expansion machine, the inside of the piston is formed hollow, and an opening is formed in the surface of the piston in the direction of reciprocal movement, and the inside of the piston is made high pressure. With a check valve to keep it,
A piston ring is swingably provided on the cylindrical peripheral surface of the piston, and the piston ring is pressed toward the cylinder side by the gas pressure inside the piston.

Further, in a specific configuration, a flexible member for maintaining airtightness between the inside of the piston and the piston ring is provided, and the piston ring is moved toward the cylinder side by the gas pressure inside the piston through the flexible member. It is to push to.

[0009]

According to the present invention, the gas pressure inside the piston is kept higher than the outside by the movement of the piston, and the gas pressure inside the piston causes the piston ring to be pressed toward the cylinder side at various points on the circumferential surface of the piston cylinder. Will be done.

Further, the gas inside the piston flows out by pressing the piston ring toward the cylinder side by the gas pressure inside the piston through a flexible member that maintains the airtightness between the inside of the piston and the piston ring. It is always kept constant without any.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a gas compression / expansion machine of the present invention applied to a Stirling refrigerator will be described below with reference to the drawings.

FIG. 1 shows a schematic structure of a Stirling refrigerator to which the present invention is applied. The Stirling refrigerator 1 has a gas flow path in which a compressor 2 and an expander 3 are interposed, and a regenerator 4 is interposed therebetween. 5, the radiators 6 and 7 are disposed on the compressor 2 side and the regenerator 4 side of the gas flow path 5, respectively, while the freezing take-out section 8 is formed on the expander 3. There is. A crank mechanism section 9 is arranged below the expander 3 and to the side of the compressor 2.

Each of the above-mentioned components of the Stirling refrigerator 1 will be described below.

The compressor 2 supplies a refrigerant gas obtained by compressing a refrigerant gas made of helium according to a predetermined cycle to the expander 3, and specifically, compresses the refrigerant gas inside the compressor body 10. The compression space 11 is formed, and the compression cylinder 12 is arranged.
A compression piston 13 slidably fitted inside 2 is reciprocated by the action of a crank mechanism portion 9 described later.

The expander 3 expands the refrigerant gas supplied from the compressor 2 via the regenerator 4. Specifically, the expander 3 serves as an expansion space inside the expander body 14 where a low temperature is generated. The freezing generating portion 17 is formed, the expansion cylinder 15 is disposed, and the expansion piston 16 slidably fitted inside the expansion cylinder 15 reciprocates by the action of a crank mechanism portion 9 described later. Has become.

The regenerator 4 is formed in a cylindrical shape between the inner circumference of the expander body 14 and the outer circumference of the expansion cylinder 15, and is a compressed refrigerant gas supplied to the expander 3 through the gas passage 5. On the other hand, when the refrigerant gas expanded and cooled in the freezing generation unit 17 is returned to the gas compressor 2 while being cooled, the refrigerant gas is cooled by the refrigerant and stores cold. Specifically, copper having a large specific heat, It is made of stainless steel, lead, or the like, and is formed into a cylindrical shape by forming a large number of fine holes through which a refrigerant gas passes.

The gas flow path 5 is a pipe for connecting the compressor 1 and the expander 2 to each other, and on the regenerator 4 side, the compressed refrigerant gas from the compression space 11 evenly passes through the regenerator 4. ing.

The radiators 6 and 7 cool the compressed high-temperature refrigerant gas to near room temperature, and the radiator 6 has a large number of disc-shaped fins provided outside the body of the compressor body 10. However, in the radiator 7, a large number of disc-shaped fins are erected on the outside of the body of the expander body 14.

The freezing take-out section 8 takes out the cold heat generated in the freezing generation section 17 to a low temperature tank (not shown) or the like, and has a plate-like body (not shown) made of stainless steel or the like on the upper portion of the expander body 14. ) Is covered.

The crank mechanism portion 9 reciprocates the compression piston 13 and the expansion piston 16 by the action of crank motion using a drive motor (not shown) as a drive source, and a guide portion to the side of the compression cylinder 12. 20 and the guide portion 21 is formed below the expansion cylinder 15. Lubricating oil 23 is stored in the bottom of the crank chamber 22 having the guide portions 20 and 21, and a crank mechanism 24 is provided inside the crank chamber 22.

The end of the connecting rod 25 extending from the crank mechanism 24 is pivotally supported by the cross guide 26 slidably fitted in the guide receiver of the guide portion 20, and the cross guide 26 is supported by the cross guide 26. The connecting piston rod 27 penetrates through the through hole of the guide portion 20 and the compression piston 13
It is attached to the rear of the. Similarly, the connecting rod 28 extending from the crank mechanism 24 is connected to the guide portion 21.
A piston rod 30 which is pivotally supported by a cross guide 29 slidably fitted in the guide receiver and is connected to the cross guide 29 is connected to the rear portion of the expansion piston 16.

An oil seal 33 is provided in the guide portion 20 in order to prevent the lubricating oil 23 in the crank chamber 22 from entering the space 32 on the back surface of the compression piston.
Similarly, in the space 35 behind the expansion piston 16, the lubricating oil 2
The guide portion 21 is provided with an oil seal 34 in order to prevent the intrusion of the oil. As a result, the insides of the compression cylinder 12 and the expansion cylinder 15 are kept oilless.

The compression piston 1 and the expansion cylinder 15 are formed without oil so that the compression piston 13 and the expansion piston 16 can move smoothly with less friction and wear.
3 and the expansion piston 16 are formed hollow inside, and check valves 40 and 41 are formed on the back side of each, and the cylindrical peripheral surface of each piston 13 and 16 facing each cylinder 12 and 15 Piston seals 36 and 37 formed of piston rings are provided in the. And, as shown in FIG. 2, each piston ring 36, 37 is
The pistons 13 and 16 are mounted on the cylindrical peripheral surface so as to be swingable in the inner and outer peripheral directions thereof, and annular flexible members 38 and 38 are provided on the inner peripheral sides of the piston rings 36 and 37, respectively.

Further, eight gas ejection holes 42 for pressing the flexible member 38 with the internal gas are uniformly formed on the cylindrical peripheral surface of the compression piston 13, and the expansion piston 1
Similarly, eight gas ejection holes 43 for pressing the flexible member 38 with the internal gas are also formed on the cylindrical peripheral surface of No. 6 at eight locations.

The operation of the check valve 40 provided on the compressor 2 side will be described below.

The check valve 40 is constructed so that it opens when the gas pressure inside the piston 13 is lower than the pressure on the rear side thereof, and closes when it becomes higher. That is, the compression piston 13 is reciprocally driven by the drive of the crank mechanism 24 of the crank mechanism unit 9, and the check valve 40 opens when each space 32 on the back side is in a compressed state (see FIG. 3), and the check valve 40 operates at other piston movements. Close it (see Figure 4),
The pressure inside the piston gradually increases and finally the space 32
It is maintained at approximately the maximum pressure that occurs in. And compression piston 1
The gas pressure inside 3 is kept higher than the outside, and the gas pressure inside the piston presses the piston ring 36 at a constant pressure against the compression cylinder 12 via the flexible member 38. The check valve 4 provided on the expander 3 side
The same operation is performed for 1.

Next, the operation of the Stirling refrigerator 1 having the above structure will be described.

First, when the crank mechanism 24 of the crank mechanism section 9 is driven by the rotation of a drive motor (not shown), the compression piston 13 in the compression cylinder 12 of the compressor 2 is driven.
Moves toward the compression space 11 and the refrigerant gas filling the compression space 11 is compressed. The compressed refrigerant gas is radiated to the outside by a radiator 6 provided on the outer periphery of the compressor body 10, cooled to near room temperature, passes through the gas flow path 5, and further cooled by a radiator 7 to the regenerator 4. Inflow.

The refrigerant gas flowing into the regenerator 4 is cooled by a material having a large specific heat, for example, a regenerator material made of copper or lead wire mesh or spheres, and the cooled refrigerant gas is frozen by the freezing generation section 17 of the expander 3. And the freezing generation unit 17 is in a high pressure state.

Thereafter, the expansion piston 16 in the expansion cylinder 15 of the expander 3 descends with a phase difference of about 90 degrees with the compression piston 13. Thereby, the freezing generation part 17 as an expansion space is expanded, and the high-pressure refrigerant gas flowing from the regenerator 4 into the freezing generation part 17 is suddenly expanded,
Since the pressure of the refrigerant gas in the freezing generation unit 17 suddenly drops, the refrigerant gas has a low temperature.

When the expansion piston 16 starts to rise and the compression piston 13 retreats, the low temperature refrigerant gas passes through the regenerator 4 and returns to the compression space 11 through the gas flow path 5. At this time, in the regenerator 4, the regenerator material is cooled and cold heat is stored in the regenerator 4.

One refrigeration cycle is completed by the steps described above, and this step is repeated by the reciprocating movement of the crank mechanism 24 of the crank mechanism section 9. This allows
The temperature of the freezing generation part 17 and the temperature of the regenerator 4 are gradually lowered, and the refrigerant gas of the freezing generation part 17 is made low in temperature. In this state, in the refrigerating / unloading section 8, the cold heat of the freezing generating section 17 is heat-exchanged with a low temperature tank (not shown) as an external heat utilizing section to set the cooling load of the external low temperature tank to the freezing temperature. .

In the Stirling refrigerator 1, if the refrigerant gas is mixed with oil, the performance of the regenerator 4 is deteriorated and the refrigerating efficiency is deteriorated. In order to prevent this, in the present embodiment, as described above, the oil seals 33 and 34 are provided on the piston rod guide portions 20 and 21, so that the lubricating oil 23 penetrates from the crank chamber 22 into the cylinders 12 and 15. Is prevented, and the inside of the cylinders 12 and 15 is made oilless.

On the other hand, if the inside of the cylinder is made oilless, the piston and the cylinder are significantly worn, and the life of the Stirling refrigerator 1 is shortened. In order to avoid such a problem, in the present embodiment, as described above, the check valves 40 and 41 are formed on the back surface of the piston so that the inside of the piston is maintained at approximately the maximum pressure generated in the spaces 32 and 35 and the piston is The internal pressure presses the piston rings 36 and 37 toward the cylinder side with a constant pressure via the flexible members 38 and 38.

As a result, even if partial displacement of the piston to the cylinder occurs due to axial runout of the piston rod, etc., the piston ring is pressed against the cylinder with a constant pressure, so that the piston rings 36, 37 wear abnormally. There is no.

In the above embodiment, the case where the present invention is applied to the Stirling refrigerating apparatus has been described, but it can be applied to other gas compression / expansion machines such as Wilmiel refrigeration machines, Solvay refrigeration machines, and Giford McMahon refrigeration machines. Applicable.

In the above embodiment, the case where the piston ring is pressed toward the cylinder side by the gas pressure inside the piston through the flexible member in order to enhance the airtightness inside the piston has been described. The piston ring may be pressed to the cylinder side by the gas pressure inside the piston, and the gas may flow out from the piston ring. In this case, some gas bearing effect can be expected due to the gas flowing out from the piston ring.

[0038]

As described above, according to the present invention, the gas pressure inside the piston is kept higher than the outside by the piston movement, and the gas pressure inside the piston causes the piston ring to have a constant pressure at various points on the circumferential surface of the piston cylinder. Will be pushed to the cylinder side.

Therefore, abnormal wear of the piston ring can be prevented, and a gas compressor / expander having a long life can be realized.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a Stirling refrigerator showing an embodiment of a gas compression / expansion device of the present invention.

FIG. 2 is a sectional view of a piston-cylinder portion of the apparatus of FIG. 1 embodiment.

FIG. 3 is a cross-sectional view of main parts for explaining the operation of the check valve of the apparatus of FIG. 1 embodiment.

FIG. 4 is a cross-sectional view of main parts for explaining the operation of the check valve of the apparatus of FIG. 1 embodiment.

FIG. 5 is a sectional view of a piston-cylinder portion in a conventional device.

[Explanation of symbols]

 1 Stirling Refrigerator 2 Compressor 3 Expander 4 Regenerator 5 Gas flow path 6, 7 Radiator 12 Compression cylinder 13 Compression piston 15 Expansion cylinder 16 Expansion piston 25, 28 Connecting rod 33, 34 Oil seal 36, 37 Piston ring ( Piston seal) 38, 38 Flexible member 40, 41 Check valve

Claims (2)

[Claims] 1. A gas compression / expansion machine for compressing or expanding gas by reciprocally moving a piston inside a cylinder, wherein the inside of the piston is formed hollow and an opening is formed on a surface in the reciprocating direction of the piston. A check valve for piercing and maintaining a high pressure inside the piston is arranged therein, and
A gas compressor / expander, wherein a piston ring is swingably provided on a cylindrical peripheral surface of the piston, and the piston ring is pressed toward the cylinder side by a gas pressure inside the piston. 2. A flexible member for maintaining airtightness between the inside of the piston and the piston ring is provided, and the piston ring is moved toward the cylinder side by gas pressure inside the piston through the flexible member. The gas compression / expansion device according to claim 1, wherein the gas compression / expansion device is pressed against.