JP2722945B2 - Cryogenic expander - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly uses helium as a working fluid, and reciprocates a slack piston and a displacer following the slack piston in a cylinder by repeatedly introducing high-pressure gas and exhausting low-pressure gas. The present invention relates to a cryogenic expander that obtains a cryogenic temperature of an absolute temperature of several tens K level.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3 and the like, as disclosed in Japanese Patent Application Laid-Open No. 62-299662, a slack piston S and a displacer interlocked with the piston S via a coupling J are provided inside a cylinder C. D, and a pouring / discharging passage T provided in a stem B serving as an end member of the cylinder C.
Communicates with a high-pressure passage extending from the external compressor unit,
By introducing high-pressure gas into the cylinder C, the pressure difference between the working chamber F of the slack piston S, which becomes high in pressure, and the opposing chamber M communicating with the intermediate pressure area via the passage R,
The slack piston S is raised, and the displacer D is raised following the slack piston S. Then, the injection / discharge passage T is switched to a low-pressure passage leading to an external compressor unit to communicate with the working chamber F, which has a low pressure. The slack piston S is lowered by the differential pressure of the intermediate pressure with the facing chamber M, and the displacer D is lowered following the slack piston S. By repeating these up and down movements, the heat stage adjoins the bottom expansion space of the cylinder C to the heat stage. Try to get cryogenic temperatures.

In this case, the displacer D is
The slack piston S moves following the movement of the slack piston S that is driven by the differential pressure, and the displacer D moves due to a slight shift in pressure that gives a driving force to the slack piston S.
Moves beyond the dead center position, coupling J and stem B
Since a collision easily occurs between the stem B and the lower surface of the stem B, a plate-shaped damper P is interposed as a buffer.

[0004]

However, when a single damper P is used as a buffer material, if a relatively soft material such as an elastomer is selected as the material in order to obtain a sufficient buffer effect, the displacer D is required. The impact load repeatedly applied along with the reciprocating motion causes the damper P to fatigue within a short period of time, causing buckling and other destruction, and causing a problem in durability. On the other hand, the material is sufficiently hard against the elastomer. If a synthetic resin material is selected, there is a problem that the cushioning effect is small, the collision noise cannot be sufficiently eliminated, and the generation of vibration cannot be effectively suppressed.

In the present invention, by devising the structure of the cushioning member, the cryogenic expansion which can sufficiently reduce the collision noise caused by the reciprocation of the displacer and the vibration generated by the collision while improving the durability thereof. The main purpose is to provide machines.

[0006]

Therefore, in order to achieve the above-mentioned main object, first, the cylinder 1 is provided inside the cylinder 1.
A slack piston 2 reciprocating with the introduction of high-pressure gas into and exhausting the low-pressure gas, and a displacer 4 interlocking with the slack piston 2 via a coupling 3 and reciprocating following the slack piston 2. In the cryogenic expander provided, the displacer 4 and the cylinder 1
Between the end member 5 and a first buffer member 61 using a soft material, and a second buffer member 62 that is harder than the first buffer member 61, and exceeds the dead center position of the displacer 4. A buffer member 6 for receiving the movement is interposed, and the first buffer member 61 is moved in the deformation direction of the first buffer member 61.
A restricting portion 63 for preventing deformation exceeding a certain range is provided.

Second, in the first means, the first cushioning member 61 is made of an elastomer O-ring 61 in order to achieve the intended purpose with a simple and inexpensive structure and satisfactorily to achieve the intended purpose.
a, and the second cushioning member 62 is
And a plate damper 62a made of a synthetic resin harder than the elastomer.
3 comprises a projection 63a projecting from the bottom of the interposition groove 61b of the O-ring 61a and receiving the plate damper 62a.

Third, in the second means, in order to avoid an increase in the size of the entire structure and to improve the assemblability and reliability, the cylinder is inserted into the slack piston 2 and the cylinder 1
A recess 51 for receiving the top of the coupling 3 is formed on the end surface of the stem 50 constituting the end member 5 of the above. The O-ring 61a and the plate damper 62a are formed in the recess 51.
The plate damper 62a is disposed on the open side and interposed, and the plate damper 6
An engaging portion 52 for preventing the 2a from falling off is provided.

[0009]

In the first half of the collision when the collision between the displacer 4 and the cushioning member 6 is started by the first means, first, the impact load is received by the deformation of the first cushioning member 61 using a soft material. And the energy of the collision is partially attenuated. This state is continued until the deformation of the first cushioning member 61 is prevented by the restricting portion 63, and then, in the late stage of the collision, the remaining energy is continuously absorbed by the hard second cushioning member 62. Thus, the deformation of the first cushioning member 61 using the soft material in the initial period of the collision is
The first buffer member 61
Fatigue can be alleviated, and its durability can be improved. Then, the cushioning action of the soft first cushioning member 61 and the hard second cushioning member 62 performed subsequently thereto are performed.
Since the energy of the collision is absorbed by the two-stage buffering action with the buffering action of the first embodiment, it is possible to reduce the generation of the sound and the vibration caused by the collision.

By the second means, the first cushioning member 61 can be formed at low cost by using the O-ring 61a,
By allowing the projecting portion 63a projecting from the bottom of the interposition groove 61b of the ring 61a to receive the plate damper 62a, following the deformation of the O-ring 61a within a certain range, the remaining energy in the latter half of the collision with the plate damper 62a smoothly. With a simple and inexpensive configuration, it is possible to favorably reduce the occurrence of collision noise and vibration.

According to the third means, the O-ring 61a and the plate damper 62 are formed in the recess 51 provided in the stem 50.
In order to accommodate the a, the O-ring 61a and the plate damper 62a are prevented from falling off by the locking portion 52 provided at the opening of the recess 51 without particularly increasing the axial length when the cushioning member 6 is interposed. Therefore, assemblability and reliability can be improved.

[0012]

FIG. 2 shows a cryogenic expander using helium as a working fluid, in which a slack piston 2 and a slack piston 2 are provided inside a cylinder 1 having an expansion space 10 and a heat stage 11 at the bottom. A displacer 4 interlocking with the piston 2 via a coupling 3 and internally holding a regenerator 40 of lead or the like is provided.

An injection / discharge passage 7 is opened in a stem 50 which constitutes the end member 5 of the cylinder 1 and protrudes inward of the slack piston 2.
By switching the valve 8 which rotates in conjunction with 0, the valve 8 alternately communicates with a high pressure passage 91 extending from the external compressor unit and a low pressure passage 92 reaching the external compressor unit. That is, when the valve 8 is switched to the position shown in the figure, the injection / discharge passage 7 is provided with a pair of communication passages 71, 71 provided continuously inside the stem 50 and a pair of side opening grooves 81, provided on the end face of the valve 8. The valve 8 communicates with the high-pressure passage 91 through the motor chamber 82 and the valve 8 from the position shown in FIG.
When it is switched to the position rotated by degrees, the communication paths 71, 7
1 and a low-pressure passage 92 through a side non-opening groove 83 provided on the end face of the valve 9, a center hole 72 provided in the stem 50, and an annular groove 73 so as to straddle between these openings. .

The working chamber 21 in contact with the end face of the slack piston 2 on the displacer side communicates with the opening side of the injection / discharge passage 7 through an inclined communication hole 22.
The opposing chamber 23 opposing 1 is communicated via an orifice 24 with a surge volume 25 held in an intermediate pressure range.

Thus, the high-pressure gas is introduced into the cylinder 1 by the communication between the injection / discharge passage 7 and the high-pressure passage 91,
The slack piston 2 is raised and the displacer 4 is raised following the slack piston 2 by the pressure difference between the high-pressure working chamber 21 and the counter pressure chamber 23, and then the injection / discharge passage 7 and the low-pressure passage 92. And the differential pressure between the low pressure working chamber 21 and the intermediate pressure counter chamber 23,
The slack piston 2 is moved down, and the displacer 4 is moved down following the slack piston 2. By repeating these operations, the cryogenic temperature of the heat stage 11 is obtained.

In the above configuration, as shown in FIG. 1, the coupling 3 of the displacer 4 and the cylinder 1
A first cushioning member 61 using a soft material and a second cushioning member 62 harder than the first cushioning member 61 are provided between the stem 50 constituting the end member 5 of FIG. In addition to interposing the buffer member 6 that receives movement beyond the point position, a restricting portion 63 that prevents deformation of the first buffer member 61 beyond a certain range in the deformation direction of the first buffer member 61 is provided.

Specifically, the first cushioning member 61 is constituted by an O-ring 61a made of an elastomer, and the second cushioning member 62
Is composed of a plate damper 62a having a flat surface in contact with the O-ring 61a and using a synthetic resin such as a polyacetal resin that is harder than the elastomer.

A coupling 3 is provided on the end face of the stem 50.
A concave portion 51 for receiving the top of the O-ring 6 is formed. A protruding portion 63a having a height slightly lower than the height of the O-ring 61 is left in the center of the concave portion 51 at the bottom of the concave portion 51.
1a, a guide wall 62b for receiving the outer periphery of the plate damper 62a is provided on the inner periphery of the recess 51, and an O-ring 61a is provided inside the recess 51.
And the plate damper 62a
a is disposed on the open side and interposed.

The O-ring 61 is formed by a projection 63a projecting from the bottom of the interposition groove 61b of the O-ring 61a.
Deformation of only a certain range of a is permitted, and after this deformation of the certain range, a restricting portion 63 that receives the plate damper 62a is formed.

Further, at the open portion of the concave portion 51, there is provided a locking portion 52 having a claw 52a projecting inward by caulking or the like and preventing the plate damper 62a from dropping off.

In the center of the plate damper 62a, an opening 621 that matches the injection / discharge passage 7 and opens the passage 7 into the cylinder 1 is opened. Equalizes the pressure between the front and back,
A plurality of screw holes 622 for connecting a jig for extracting the plate damper 62a during maintenance are opened.

With the above arrangement, the displacer 4 moves upward following the upward movement of the slack piston 2, and in the first half of the collision when the collision between the top surface of the coupling 3 and the cushioning member 6 starts, The impact load is received by the deformation of the O-ring 61a, and the energy of the collision is partially attenuated.
Then, in the late stage of the collision in which the O-ring 61a is deformed over a certain range and the plate damper 62a is received by the protruding portion 63a, the remaining energy is continuously absorbed by the hard plate damper 62a. in this case,
The deformation of the O-ring 61a in the initial period of the collision
a, the O-ring 61
a can be alleviated and its durability can be improved. Since the energy of the collision is absorbed by the two-stage buffering action of the buffering action of the O-ring 61a and the subsequent buffering action of the plate damper 62a, the generation of the sound and the vibration caused by the collision is reduced. You can do it.

In the above, the O-ring 61a is used, and after the O-ring 61a is deformed within a certain range, the protruding portion 63a protrudes from the bottom of the interposition groove 61b.
The plate damper 62a
Following the deformation of the O-ring 61a within a certain range, the plate damper 62a can smoothly receive the residual energy in the late stage of the collision, and has a simple and inexpensive configuration, and can favorably reduce the generation of collision sound and vibration. You can.

Further, in the above-described structure, the O-ring 61a and the plate damper 62 are provided in the recess 51 provided in the stem 50.
a, the length of the shaft is not particularly increased when the cushioning member 6 is interposed, and the recess 51
Since the locking portion 52 provided at the opening portion can prevent the O-ring 61a and the plate damper 62a from falling off, the assemblability and reliability can be improved.

[0025]

According to the first aspect of the present invention, the first buffer member 61 made of a soft material and the hard second buffer member 62 are used.
And a restricting portion 63 for preventing deformation of the soft first cushioning member 61 beyond a certain range is provided.
While improving the durability of the cushioning member 6, it is possible to sufficiently reduce the collision sound caused by the reciprocation of the displacer 4 and the vibration generated by the collision.

According to the second aspect of the present invention, an O-ring 61a made of an elastomer is used, and a plate damper 62a made of synthetic resin is provided on a protruding portion 63a protruding from the bottom of the interposition groove 61b of the O-ring 61a. As a result, the generation of collision noise and vibration can be reduced with a simple and inexpensive structure.

According to the third aspect of the present invention, the stem 50
Since the O-ring 61a and the plate damper 62a can be accommodated in the recess 51 provided in the base plate, and the locking portion 52 for preventing the plate damper 62a from dropping is provided, the overall structure can be prevented from being enlarged, and the assembling and reliability can be avoided. It can also improve the performance.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a main part of a cryogenic expander according to the present invention.

FIG. 2 is a sectional view showing the entire structure.

FIG. 3 is a sectional view of a conventional cryogenic expander.

[Explanation of symbols]

1; cylinder; 2; slack piston; 3; coupling; 4; displacer, 5; end member, 50; stem, 51; recess, 52;
First buffer member, 61a; O-ring, 61b;
2; second buffer member, 62a; plate damper, 63;
Regulating part, 63a; projecting part

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-49859 (JP, A) JP-A-64-8167 (JP, U)

Claims (3)

(57) [Claims] 1. A slack piston 2 reciprocating between the introduction of a high-pressure gas into the cylinder 1 and the exhaust of a low-pressure gas, and a coupling 3 connected to the slack piston 2.
And a displacer 4 that reciprocates following the slack piston 2 in a cryogenic expander, in which a soft material is placed between the displacer 4 and the end member 5 of the cylinder 1. First buffer member 61 used
And a second cushioning member 62 harder than the first cushioning member 61
A buffer member 6 for receiving the displacement of the displacer 4 beyond the dead center position, and preventing the first buffer member 61 from deforming beyond a certain range in the deformation direction of the first buffer member 61. A cryogenic expander characterized by having a regulating portion 63 that performs the operation. 2. The first cushioning member 61 comprises an O-ring 61a made of an elastomer, and the second cushioning member 62 has a flat surface in contact with the O-ring 61a and is made of a synthetic resin harder than the elastomer. Consisting of a damper 62a,
The cryogenic expander according to claim 1, wherein the restricting portion (63) comprises a protruding portion (63a) protruding from the bottom of the interposition groove (61b) of the O-ring (61a) and receiving the plate damper (62a). 3. A recess 51 which protrudes inward of the slack piston 2 and which receives the top of the coupling 3 is formed on an end face of a stem 50 which constitutes the end member 5 of the cylinder 1.
An O-ring 61a and a plate damper 62a are interposed in the recess 51 with the plate damper 62a disposed on the open side, and a locking portion for preventing the plate damper 62a from dropping is provided in the open portion of the recess 51. The cryogenic expander according to claim 2, further comprising: 52.