JP2000055493A - Piston shock absorber for gas cycle refrigeration device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for absorbing a shock against a cylinder wall surface of a piston and suppressing generation of vibration in a free piston type gas cycle refrigeration device. SOLUTION: A piston 2 is reciprocatingly and slidably installed in a cylinder 1, a variable volume chamber 7 is formed in the cylinder 1, and the variable volume chamber 7 is switched and connected to the delivery side and the suction side of a compressor 14. A first magnet 26 is installed at least on the large diameter side end face. A second magnet 27 is installed on a cylinder wall surface opposing to a magnet installation end surface of the piston 2 in such a manner as to repulse the first magnet 26.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock absorber for a piston in a gas cycle refrigeration system using gas as a working material.

[0002]

2. Description of the Related Art Conventionally, a piston is reciprocally slidably mounted in a cylinder, a high-pressure gas from a compressor is introduced into a space formed by the cylinder and the piston, and the high-pressure gas is adiabatically expanded. For example, there is a refrigerator shown in FIG.

[0003] In this method, a stepped piston (52) having a large-diameter portion and a small-diameter portion is disposed in a cylinder (51) so as to be reciprocally slidable, and a large-diameter portion (53) and a small-diameter portion of the piston (52) are arranged. The seal rings (55) and (56) are fitted to the (54), respectively, and the seal ring (55) fitted to the large-diameter portion (53) of the piston (52) and the large-diameter side end surface of the cylinder (51). A variable capacity chamber (57) is formed between them,
Seal ring (55) fitted to the large diameter part (53) of the piston (52)
And a low pressure chamber (58) between the seal ring (56) fitted to the small diameter portion (54), and a high pressure chamber (59) between the small diameter seal ring (56) and the small diameter end face of the cylinder (51). ) Are respectively formed, and a gas supply / discharge path (60) for supplying / discharging the working gas to / from the variable capacity chamber (57) is branched, and a gas supply / discharge path (6
0), a refrigeration output extraction heat exchanger (61) and a regenerator (62) are arranged in order from the cylinder (51) side, and one branch pipe (63) is connected to the compressor.
(64) is connected to the discharge port (65) of the compressor (64) via the high pressure switching valve (66), and the other branch pipe (67) is connected to the suction port (68) of the compressor (64) by the low pressure switching valve (69). The high-pressure chamber (59) is connected to the discharge port (65) of the compressor (64) through the high-pressure gas passage (70), and is connected to the low-pressure chamber (58).
Are connected to the suction port (68) of the compressor (64) through the low-pressure gas passage (71), and fixed throttle valves (72) (73) are interposed in the high-pressure and low-pressure gas passages (70) (71), respectively. It has a structured structure. Note that the high-pressure switching valve (66) and the low-pressure switching valve (69) are configured as rotary valves that are switched by the same rotating shaft, and are configured so that both switching valves are alternately opened.

[0004]

In this type of gas cycle refrigerator, the movement of the piston (52) depends on the difference between the pressure in the variable capacity chamber (57) and the pressure in the high pressure chamber (59) and the low pressure chamber (58). The movement speed of the piston (52) is
(72) It is determined by the fluid resistance of (73). Here, when the variable capacity chamber (57) communicates with the discharge port (65) of the compressor (64) and the high pressure gas flows into the variable capacity chamber (57), the pressure of the variable capacity chamber (57) and the high pressure chamber ( The piston (52) moves toward the high pressure chamber (59) due to the pressure difference between the pressure in the low pressure chamber (58) and the pressure in the low pressure chamber (58). During this movement, the collision between the piston (52) and the cylinder (51) is unlikely to occur because the internal pressure of the high-pressure chamber (59) acts as a damper.
However, when the variable capacity chamber (57) communicates with the suction port (68) of the compressor (64), the pressure acting on the high pressure chamber (59) increases the piston pressure.
(52) is a force for moving the variable displacement chamber (57) to the variable displacement chamber (57), and there is nothing in the variable displacement chamber (57) to buffer this piston movement. 57)
There is a problem in that it collides with the wall surface of the device and generates vibration. Since the variable capacity chamber (57) is in a low-temperature state, there is no one capable of stably exhibiting a sufficient buffering force in a low-temperature state. Therefore, it is a fact that the collision of the piston is neglected.

The present invention has been made in view of such a point, and provides an apparatus for damping the collision of a piston with a cylinder wall in a free-piston type gas cycle refrigeration system and suppressing the generation of vibration. With the goal.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a cylinder having a stepped piston having a first magnet mounted on at least a large-diameter end face thereof and facing a magnet mounting end face of the piston. It is characterized in that the second magnet is mounted on the wall surface in a state of repelling the first magnet.

[0007]

According to the present invention, the first magnet is mounted on at least the large-diameter end face of the stepped piston that reciprocates,
Since the second magnet is arranged on the cylinder wall surface opposite to the magnet mounting end surface in a state of repelling the first magnet, the piston end surface and the cylinder wall surface move as the piston end surface approaches the cylinder wall surface when the piston reciprocates. Since the magnetic repulsive force acting between the cylinders increases sequentially, the increased magnetic repulsive force acts as a buffering force to suppress the piston from colliding with the cylinder wall surface.

[0008]

FIG. 1 is a schematic view of a refrigerating apparatus showing an embodiment of the present invention. In this refrigerating apparatus, a stepped piston (2) is reciprocally slidably fitted inside a stainless steel cylinder (1), and a large diameter portion (3) and a small diameter portion (4) of the piston (2).
Are fitted with seal rings (5) and (6), respectively. And a seal ring fitted to the large diameter portion (3) of the piston (2)
Variable capacity chamber between (5) and the large diameter end face of cylinder (1)
A low-pressure chamber (8) is formed between the seal rings (5) and (6) formed on the large-diameter portion (3) and the small-diameter portion (4), respectively.
And a high-pressure chamber between the seal ring (6) fitted to the small-diameter portion (4) of the piston (2) and the small-diameter side end surface of the cylinder (1).
Formed in (9).

A gas supply / discharge passage (10) for supplying / discharging working gas to / from the variable capacity chamber (7) is branched, and a cylinder is provided in the gas supply / discharge passage (10) between the variable capacity chamber (7) and the branch portion. From the side, a refrigeration output extraction heat exchanger (11) and a regenerator (12) are arranged in order, and one branch pipe (13) is connected to a high-pressure gas derived from a discharge port (15) of a compressor (14). Connected to the passage (16) via a high-pressure switching valve (17), and connected the other branch pipe (18) to the suction port (19) of the compressor (14).
Low-pressure switching valve (21) in low-pressure gas passage (20) derived from
Connected via The high-pressure switching valve (17) and the low-pressure switching valve (21) are constituted by rotary valves operated by the same drive motor.

The high-pressure gas passage (16) is connected to the high-pressure chamber (9).
The low-pressure gas passages (20) are respectively connected to the low-pressure chambers (8). The high-pressure gas passage (16) has a high-pressure throttle valve (22)
However, a low-pressure throttle valve (24) is provided in the low-pressure gas passage (20).

In an actual apparatus, high and low pressure throttle valves (22) and (24) disposed in a high pressure gas passage (16) and a low pressure gas passage (17) are used.
Is formed by an orifice penetrating the wall of the cylinder (1). In this embodiment, the high / low pressure throttle valves (22) and (24) are formed by orifices. However, each of the throttle valves (22) and (24) may be configured by a needle valve.

In the refrigeration apparatus thus constructed, the present invention provides a refrigeration apparatus in which a first ring-shaped magnet (26) is buried at the end face of a large diameter portion of a stepped piston (2), and the variable capacity chamber (7) is provided. With the second ring-shaped magnet (27) facing the wall of the piston (2) facing the magnet mounting surface with the same poles facing each other, both magnets have the same diameter or the cylinder-side magnet has a larger diameter. Are arranged on the circumference of the cylinder, and the collision of the piston (2) with the wall of the cylinder (1) is cushioned by the repulsive force of the magnetic force acting between the magnets (26) and (27).

When the magnets (26) and (27) are arranged between the end face of the piston (2) and the wall surface of the cylinder (1) facing the end face, respectively, and the two magnets have repulsive force, Since the so-called run-out occurs in a direction perpendicular to the direction of movement of the piston (2), the end of the piston (2) on the peripheral wall of the large diameter portion and the variable capacity chamber in the cylinder (1)
Ring-shaped side magnets (28) and (29) are respectively buried and arranged at the end of the peripheral wall surface of (7) so as to generate a repulsive force by magnetic force. With the magnetic force acting on the side magnets (28) and (29), the center runout of the piston (2) can be suppressed.

FIG. 2 shows a modification of the arrangement position of the magnet, in which a ring-shaped side magnet (29) is arranged on the inner peripheral surface of the cylinder in the variable capacity chamber (7), and the side magnet on the piston side is omitted. It was done. In this case, the cylinder
The side magnet (29) mounted on the inner peripheral surface of the variable capacity chamber (7) of (1) is formed by a ring-shaped magnet having inner and outer peripheral portions formed on the extreme surfaces, and its magnetic force lines are formed by the piston (2). The first magnet (26) disposed on the end face of the first magnet (26) faces the magnetic field line.

FIG. 3 shows another modification of the arrangement position of the magnet, which is a first modification which is embedded in the end face of the piston (2).
The magnet (26) is formed of a disk-shaped or ring-shaped magnet, and the second magnet (27) buried in the cylinder end surface of the variable capacity chamber (7) has a larger inner diameter than the first magnet (26). It is composed of a shape magnet. By doing so, both magnets (2
6) Due to the relationship of the lines of magnetic force acting on (27), it is possible to suppress center runout without disposing a side magnet.

The magnet used in the present invention is preferably a magnet formed of a rare earth magnet such as a neodymium-based, cerium-based, or samarium-based magnet.

In the above embodiment, the variable capacity chamber (7)
In the above description, the magnet was arranged between the piston (2) and the cylinder (1).
A magnet may be arranged on the piston (2) and the cylinder (1) in (8) to cushion the collision between the piston (2) and the cylinder (1).

In the refrigerator having the above configuration, the piston
When the high-pressure switching valve (17) is opened and the low-pressure switching valve (21) is closed with (2) in the lowered position, high-pressure gas from the compressor (14) flows into the variable capacity chamber (7). Push up the piston (2). At this time, the pressure of the high-pressure gas is also acting on the high-pressure chamber (9), but the piston (2) is pushed up by the pressure receiving area difference, and its moving speed is high pressure chamber (9) and low-pressure chamber (9). It is controlled by the degree of opening of the high and low pressure throttle valves (22) and (24) interposed in the high and low pressure gas passages (16) and (20) to 8).

When the piston (2) reaches the upper end,
When the high pressure switching valve (17) is closed and the low pressure switching valve (21) is opened, the variable capacity chamber (7) communicates with the suction port (19) of the compressor (14). Descend, variable capacity chamber
The high-pressure gas in (7) expands adiabatically, causing cold. In this case, the wall of the cylinder (1) functions as a heat exchanger for extracting the refrigeration output.

A high / low pressure throttle valve is provided in a high pressure gas passage (16) to the high pressure chamber (9) and a low pressure gas passage (17) to the low pressure chamber (8).
(22) and (24) are arranged, and the high pressure gas from the compressor (14) flows into the variable capacity chamber (7) and the piston (2) is
When moving to the side of increasing the volume of (7), the high-pressure gas passage (16) and the low-pressure gas passage (17) are each provided with a high / low pressure throttle valve.
(22) The communication is performed only by (24), and the moving speed of the piston (2) is reduced. Moreover, the high-pressure chamber (9) is
Since the high-pressure gas flows into the high-pressure chamber (9) since the high-pressure gas flows into the high-pressure chamber (9) because it is connected to the discharge port (15) of (4), the high-pressure gas acts as a gas cushion.
The piston (2) hardly collides with the wall surface of the cylinder (1) during the movement for increasing the capacity of the variable capacity chamber (7) of (2) (at the time of ascending movement).

On the other hand, when the variable capacity chamber (7) communicates with the suction port (19) of the compressor (14) and the piston (2) moves to the side of decreasing the volume of the variable capacity chamber (7) High pressure gas passage (16) and low pressure gas passage (17)
(24) communicate with each other so that the high-pressure gas smoothly flows into the high-pressure chamber (9), and that a part of the gas discharged from the variable capacity chamber (7) smoothly flows into the low-pressure chamber (8). Become. As a result,
The piston (2) can be operated at full stroke even at the time of low-temperature output, and stable cold is generated in the refrigeration output extraction heat exchanger (11), and the ultimate temperature as a refrigerator can be lowered. At this time, the magnet (2) is placed on the large-diameter end face of the piston (2) and on the cylinder wall facing the end face.
(26) Since (27) is arranged in a state of rebound, the piston
When the large-diameter end of (2) approaches the cylinder wall in the variable capacity chamber (7), the two magnets (26) and (27) acting in the direction of repulsion
As a result, the piston (2) is braked by the magnetic force of (2), so that the piston (2) is prevented from colliding with the cylinder wall.

This prevents the piston (2) reciprocating in the cylinder (1) from colliding with the wall surface of the cylinder (1), so that vibration and noise can be prevented. When used for cooling a device that does not like the influence of magnetic force, the outer circumference of the cylinder (1) is magnetically shielded.

[0023]

According to the present invention, the first magnet is mounted on at least the large-diameter end face of the stepped piston that reciprocates,
Since the second magnet is disposed on the cylinder wall surface facing the magnet mounting end surface in a state of repelling the first magnet, the piston end surface approaches the cylinder end surface as the piston large diameter side end surface approaches the cylinder wall surface during reciprocation of the piston. Since the magnetic repulsive force acting between the cylinder wall surface and the cylinder wall surface increases sequentially, the increased magnetic repulsive force acts as a buffering force, thereby suppressing the piston from colliding with the cylinder wall surface. As a result, the generation of vibration and noise due to the collision can be suppressed, so that it is possible to measure an analyzer or a cooled test body that gazes at the vibration and improve the performance.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a refrigeration apparatus showing one embodiment of the present invention.

FIG. 2 is a schematic view of a main part taken out in different embodiments.

FIG. 3 is a schematic view of a main part taken out in still another embodiment.

FIG. 4 is a schematic diagram showing a conventional refrigeration apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... cylinder, 2 ... piston, 7 ... variable capacity chamber, 14 ... compressor, 26 ... 1st magnet, 27 ... 2nd magnet, 29 ...
Side magnet.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Etsuji Kawaguchi 1095 Katsube-cho, Moriyama City, Shiga Prefecture Inside Iwatani Gas Co., Ltd. (72) Inventor Masato Adachi 1095 Katsube-cho, Moriyama City, Shiga Prefecture Iwatani Gas Co., Ltd.

Claims (3)

[Claims] 1. A gas cycle refrigeration system in which a variable capacity chamber (7) in a cylinder (1) is switchably connected to a discharge side and a suction side of a compressor (14). A state in which the first magnet (26) is mounted on at least the large-diameter end face, and the second magnet (27) is repelled from the first magnet (26) on the cylinder wall surface facing the magnet mounting end face of the piston (2). A piston shock absorber in a gas cycle refrigeration system, wherein the piston shock absorber is mounted. 2. The piston shock absorber in a gas cycle refrigeration system according to claim 1, wherein the second magnet (27) mounted on the end face of the cylinder (1) is formed of a ring-shaped magnet. 3. A piston cushion in a gas cycle refrigeration system according to claim 1, wherein a ring-shaped side magnet (29) is mounted on a peripheral wall surface of the variable capacity chamber (7) of the cylinder (1). apparatus.