JPH08261580A - Cryogenic expander - Google Patents

Abstract

(57) [Summary] [Purpose] Each of the front and rear displacers 1 and 2 is brought close to its ideal capacity, and each person exhibits a high cooling capacity to improve the overall capacity. [Composition] In a cryogenic expander equipped with a plurality of displacers 1 and 2, at the connecting portion of each displacer 1 and 2, with respect to the reciprocating stroke of the preceding displacer 1,
A predetermined play is provided to shorten the reciprocating stroke of the rear displacer 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention mainly uses helium as a working fluid to obtain an extremely low temperature of several K to several tens of K absolute temperature.
The present invention relates to a cryogenic expander that cools various cryogenic samples such as superconducting magnets and devices.

[0002]

2. Description of the Related Art Conventionally, a cryogenic expander having a plurality of stages of displacers is known, for example, from Japanese Patent Laid-Open No. 7-27434. In the publication, as shown in FIG. 7, inside the large diameter cylinder C1 and the small diameter cylinder C2 in the cylinder C,
A front displacer D1 and a rear displacer D2 are arranged so as to freely reciprocate.
The two are integrally connected to each other via a connecting body A. Then, in the large diameter cylinder C1 of the cylinder C,
The front-stage displacer D1 is reciprocally driven, and accordingly, the rear-stage displacer D2 integrally coupled by the connecting body A is reciprocally moved in the small-diameter cylinder C2.
By supplying and discharging a working fluid such as helium to and from the animal storage cooler pieces B1 and B2 loaded in the inside of the animal storage cooler pieces B1 and B2,
The cold heat is stored in the front and rear heat stages F and S located at the lower ends of the large and small diameter cylinders C1 and C2.
Each is cooled to a very low temperature.

[0003]

However, in the above cryogenic expander, the displacers D1 and D of the front and rear stages are disposed.
Since the two are integrally connected to each other in the axial direction by the connecting body A and they reciprocate integrally, the strokes of the front and rear displacers D1 and D2 are the same.

On the other hand, as shown in FIG. 5, ideal strokes ST1 and S that can exhibit their maximum abilities P1 and P2 in the respective performance curves a and b of the front and rear displacers.
There is a difference in T2, and the stroke ST2 on the rear displacer side is the stroke ST1 of the front displacer D1.
Is shorter than. Usually, since the design is performed by emphasizing the minimum reached temperature in the heat stage S on the rear side, the stroke is the ideal stroke ST2 on the side of the rear displacer.
Therefore, on the displacer side of the former stage, the capability is lowered to P3. Especially, in recent years, in the case where the displacer is equipped with a magnetic regenerator and the last heat stage is lowered to about several K, it is necessary to design with emphasis on the latter stage side, and the performance in stages other than the last stage becomes worse. There is. Note that FIG. 5 shows the characteristics under the condition that the rotation speed of the valve motor that supplies and discharges gas into and from the cylinder C is constant.

An object of the present invention is to provide a cryogenic expander capable of exhibiting high performance as a whole by providing different strokes so that the maximum performance can be exhibited by the front and rear displacers.

[0006]

In order to achieve the above object, the invention according to claim 1 is, as shown in FIG. 1, a plurality of reciprocating motions in the cylinder 4 by supplying and discharging the working fluid. In the cryogenic expander including the displacers 1 and 2, the reciprocating stroke of the rear displacer 2 is shorter than the reciprocating stroke of the front displacer 1 at the connecting portion between the front displacer 1 and the rear displacer 2. It is configured to have a predetermined play.

In order to achieve the intended purpose with a simple structure, the invention according to claim 2 is, as shown in FIG.
In the invention described above, the pre-stage displacer 1 and the post-stage displacer 2 are connected to each other through a long hole 5 that secures a stroke difference between the displacers 1 and 2 and a pin 6 that is received in the long hole 5. did.

According to a third aspect of the present invention, in order to further improve the sliding of the displacers 1 and 2 in the cylinder 4 in the second aspect of the invention, as shown in FIG. The rear displacer 2 and the rear displacer 2 are connected to each other via a joint body 7 which is swingably mounted. A long hole 5 and a pin 6 are provided between the joint body 7 and a mounting portion of the joint body 7. It is configured to be.

The invention according to claim 4 is the same as the invention according to claim 2 or 3, in order to reduce the impact force between the elongated hole 5 and the pin 6, as shown in FIG. The cushioning material 60 is interposed between the contact locking portion between the pin 5 and the pin 6.

In order to achieve the intended purpose with another simple structure other than the long hole 5 and the pin 6, the invention according to claim 5 is as follows.
As shown in FIG. 4, the front displacer 1 and the rear displacer 2 are connected via the slack pin 8 and the engaging portion 9 having the forward movement side contact portion 91 and the backward movement side contact portion 92 that abut and engage with the slack pin 8. They are connected to each other, and a stroke difference between the front stage displacer 1 and the rear stage displacer 2 is secured between the forward movement side contact portion 91 and the backward movement side contact portion 92.

According to a sixth aspect of the invention, in order to reduce the impact force between the slack piston 8 and the engaging portion 9 in the fifth aspect of the invention, as shown in FIG. The cushioning material 90 is interposed at the contact portion between the forward movement side contact portion 91 and the backward movement side contact portion 92 in the engagement portion 9.

[0012]

According to the invention described in claim 1, as shown in FIGS. 1 to 3, a play is provided between the connecting portions of the front and rear displacers 1 and 2 to shorten the reciprocating stroke of the rear stage with respect to the front stage. As a result, the stroke of the front displacer 1 can be increased, and the stroke of the rear displacer 2 can be shortened by the amount of play, and the displacers 1 and 2 can be brought closer to the ideal strokes that can maximize their performance. Can be improved.

According to the second aspect of the present invention, when the play is provided between the connecting portions of the displacers 1 and 2, the elongated hole 5 for ensuring the stroke difference between the displacers 1 and 2 and the pin 6 received in the elongated hole 5 are provided. Therefore, the intended purpose of improving the capabilities of the displacers 1 and 2 and improving the overall capabilities can be realized with a simple configuration.

According to the third aspect of the invention, the joint body 7 is interposed between the displacers 1 and 2 so that the joint body 7 can freely swing, and the long hole 5 and the pin 6 are provided between the joint body 7 and its mounting portion. Since the and are provided, the intended purpose can be achieved with a simple configuration,
Good slidability of each displacer 1, 2 in the cylinder 4 can be ensured.

According to the fourth aspect of the present invention, the cushioning material 60 provided in the contact locking portion between the long hole 5 and the pin 6 causes the pin 6 to contact the locking portion when the displacers 1 and 2 reciprocate. The impact force can be relieved, and the long holes 5 and the pins 6 can be prevented from being damaged.

According to the fifth aspect of the invention, as shown in FIG. 4, the displacers 1 and 2 are connected to each other by the slack pin 8 and the engaging portion 9, and the engaging portion 9 is moved forward and backward. Since a predetermined stroke difference is secured between the abutting portions 91, 92, the stroke difference enhances the capabilities of the displacers 1 and 2 with a simple structure, as in the case described above. The overall ability can be improved.

According to the invention of claim 6, the slack pin 8 is provided.
Since the cushioning material 90 is interposed in the contact portion between the forward movement side contact portion 91 and the backward movement side contact portion 92 in the engaging portion 9, the reciprocating movement of the displacers 1 and 2 is performed. At the same time, it is possible to reduce the impact force of the slack pin 8 on the contact portions 91 and 92, and to prevent the slack pin 8 and the engagement portion 9 from being damaged.

[0018]

EXAMPLE A cryogenic expander shown in FIG. 6 has a pre-stage displacer 1 in which a large number of regenerator pieces 3a, 3b are loaded.
And a rear displacer 2, a cylinder 4 having a large-diameter cylinder 41 and a small-diameter cylinder 42 into which the respective displacers 1 and 2 are inserted, and a cylinder 4 which is housed in the cylinder 4 and connected to the front displacer 1 side via a coupling J And a slack piston P. And the valve motor W
By switching the valve V which is interlocked with, the injection and discharge passage T provided in the valve stem BS is made to communicate with the high pressure passage H extending from the external helium compressor, and high pressure gas is introduced into the cylinder 4, whereby slack becomes high. The differential pressure between the working chamber Q of the piston P and the counter chamber K communicating with the intermediate pressure chamber M via the orifice O raises the slack piston P and the displacers 1 and 2, and then the pouring discharge passage T.
To the low pressure passage L leading to the helium compressor so that the low pressure passage L communicates with the low pressure working chamber Q and the intermediate pressure counter chamber K.
The slack piston P and the displacers 1 and 2 are lowered by the pressure difference between the slack piston P and the displacers 1 and 2. In this way, by repeatedly moving the displacers 1 and 2 up and down, cold heat is stored in the regenerator pieces 3a and 3b therein, and the large diameter cylinder 4
A cryogenic temperature of about several tens of K is applied to the front heat stage F adjacent to the bottom expansion space E of No. 1 and a lower temperature of about several K is applied to the rear heat stage S adjacent to the bottom expansion space R of the small diameter cylinder 42. I am trying to get it.

However, in the present invention, as is apparent from FIG. 1, a receiving hole 21 having an upper opening is formed on the upper side of the rear displacer 2, and a rod-shaped joint body is formed in the receiving hole 21 via a connecting pin 22. 7 is swingably and directly supported, and at the upper side of the joint body 7, a long hole 5 is formed in the up-down direction for ensuring a predetermined play for shortening the reciprocating stroke of the rear displacer 2 side with respect to the front displacer 1. Form. Further, on the lower side of the front displacer 1, a receiving hole 11 which is open at the lower part and which can receive the joint body 7 is formed,
A pin 6 extending in a direction orthogonal to the connecting pin 22 is provided between the wall portions of the receiving hole 11, and the pin 6 is inserted into the elongated hole 5 so that the pin 6 and the connecting pin 22 are interposed therebetween. The joint body 7 is supported so as to swing freely in four directions of front, rear, left and right.

More specifically, when the stroke from the top dead center to the bottom dead center of the front displacer 1 is ST1 and the stroke from the top dead center to the bottom dead center of the rear displacer 2 is ST2, ST2 becomes ST1. On the other hand, by providing a stroke difference between the two so as to be smaller by a predetermined value and providing a play corresponding to the stroke difference in the elongated hole 5, as shown in FIG.
Of maximum stroke P1 and P2
2 is obtained.

The abutment and locking portions of the pin 6 at the upper and lower portions of the elongated hole 5 buffer the impact of the pin 6 on the elongated hole 5 when the pin 6 moves up and down to follow the joint body 7. A pair of upper and lower cushioning materials 60, 60 made of anti-vibration rubber and leaf spring material are provided. The cushioning material 60 may be provided on the pin 6 side.

In FIG. 1, reference numeral 12 is a fluid passage on the front stage displacer 1 side, and 23 and 24 are fluid passages on the rear stage displacer 2 side.

Next, the operation of the above configuration will be described. In FIG. 1, high-pressure gas from the high-pressure passage H is introduced into the working chamber Q of the slack piston P in the cylinder 4, and due to the pressure difference between this working chamber Q and the counter chamber K,
The displacers 1 and 2 are shown in a state of being raised to the top dead center position. At this time, the pin 6 provided on the front displacer 1 side is in a state of being abutted and locked on the upper end side of the elongated hole 5 provided on the joint body 7.

From this state, the pouring / discharging passage T becomes the low-pressure passage L.
When the pre-stage displacer 1 is lowered to the bottom dead center side due to the pressure difference between the working chamber Q that is in low pressure and the counter chamber K that has an intermediate pressure, as shown in FIG. Only the front displacer 1 descends until it abuts the lower end of 5, and the pin 6 abuts the lower end of the elongated hole 5, and then the rear displacer 2 descends toward the bottom dead center over the range of its stroke ST2.

Finally, as shown in FIG. 3, the front displacer 1 and the rear displacer 2 are located at the bottom dead center position.

The same applies to the case of moving from the bottom dead center to the top dead center. Only the front displacer 1 rises until the pin 6 contacts the upper end of the elongated hole 5, and the pin 6 contacts the upper end of the elongated hole 5. After contact, the rear displacer 2 has its stroke S.
It is raised to the top dead center side over the range of T2.

As described above, the stroke ST1 of the front displacer 1 is increased, while the stroke ST1 of the rear displacer 2 is increased.
The stroke ST2 of the
Is set so that the peaks P1 and P2 of the performance curves a and b shown in FIG. 5 are obtained, it is possible to make the respective displacers 1 and 2 exhibit their ideal performances, and Can be improved. Further, when the displacers 1 and 2 reciprocate as described above, the shocks of the pins 6 on the elongated holes 5 are alleviated by the cushioning materials 60 provided above and below the elongated holes 5, respectively. The damage of the pin 6 is prevented. Further, the joint body 7 is interposed between the displacers 1 and 2 via the pin and the connecting pin 22 so that the displacer 1 and the inside of the cylinders 41 and 42 of the cylinder 4 can be freely swung. Can be slid smoothly.

The joint body 7 has its upper side pivotally supported on the front displacer 1 side through a connecting pin 22, and has a long hole 5 provided on the lower side, which is supported by the rear displacer 2. You may let me accept the pin. Further, the elongated hole 5 may be formed on the side of the receiving holes 11 and 21, and the pin 6 may be fixed either above or below the joint body 7.

Further, in the present invention, as shown in FIG. 4, instead of the joint body 7 described above, a slack pin 8 having a flange-shaped locking portion 81 at its upper end is provided so as to project on the upper side of the rear displacer 2. At the same time, the front displacer 1 side is formed with an opening part of which is cut inward at the lower end side thereof.
Forming an engaging portion 9 having a forward-moving-side abutting portion 91 and a backward-moving-side abutting portion 92 that abut and engage with each other, and let the locking portion 81 intervene in the engaging portion 9. While connecting the displacers 1 and 2 with each other by the above, the stroke on the side of the rear displacer 2 is smaller than that of the displacer 1 on the front side between the forward and backward contact portions 91, 92. You may make it provide the same stroke difference.

Also according to the above structure, when the displacers 1 and 2 are reciprocated in the vertical direction, the stroke difference ensured between the forward movement and the return movement side contact portions 91 and 92 of the engaging portion 9 causes the above-mentioned difference. As in the case of the above, the capabilities of the displacers 1 and 2 can be increased and the overall capabilities can be improved.

Further, in the figure, when the slack pin 8 moves up and down, the engaging portion 9 is brought into contact with the engaging portion 9.
The forward and backward contact portions 91 and 92 are provided with cushioning materials 90 and 90 made of a vibration-proof rubber or a leaf spring material, respectively. In doing so, when the displacers 1 and 2 reciprocate, the contact portions 91 and 92 of the slack pin 8 are reciprocated.
It is possible to alleviate the impact force on the slack pin and prevent the slack pin 8 and the engagement part 9 from being damaged. The slack pin 8 may be provided on the front displacer 1 side, and the engaging portion 9 may be provided on the rear displacer 2 side. Further, the locking portion 81 of the slack pin 8 can be formed by a plurality of rods protruding in the radial direction.

Further, in the above embodiment, the two-stage type using the front and rear displacers 1 and 2 has been described, but the present invention may have two or more displacers. Then, for example, in the case of the three-stage type, the first stage is usually used Cu, Pb, Sus,
Al or other metal cooling material, a magnetic cooling material such as Er ₃ Co having a peak of specific heat at 4 to 25 K in the second stage,
Further, in the third stage, there is a sharp peak of specific heat at 2 to 6K, and the specific heat becomes small near 15K, for example ErNi, ErN.
It is preferable to load a magnetic storage medium such as i ₂ .

[0033]

As described above, according to the first aspect of the invention, the stroke of the front displacer 1 can be increased and the stroke of the rear displacer 2 can be shortened by the amount of play of the connecting portion, so that the maximum capacity of each displacer 1 and 2 can be obtained. It is possible to bring the stroke closer to the ideal stroke that can be exhibited and improve the overall ability.

According to the second aspect of the present invention, the intended purpose can be realized with a simple structure by the elongated hole 5 and the pin 6 received in the elongated hole 5.

According to the third aspect of the present invention, since the elongated hole 5 and the pin 6 are provided between the joint body 7 which is free to swing, and its mounting portion, the intended purpose is simple. While being realized, it is possible to secure good slidability of each displacer 1, 2 in the cylinder 4.

According to the fourth aspect of the present invention, the buffer member 60 provided at the contact locking portion between the elongated hole 5 and the pin 6 causes the pin 6 to contact and lock when the displacers 1 and 2 reciprocate. The impact force on the portion can be mitigated, and the long holes 5 and the pins 6 can be prevented from being damaged.

According to the fifth aspect of the present invention, the displacers 1 and 2 are connected by the slack pin 8 and the engaging portion 9, and the forward and backward contact portions 91, 91 of the engaging portion 9 are connected.
Since a predetermined stroke difference is secured between 92, it is possible to improve the capabilities of both displacers 1 and 2 and improve the overall capabilities with a simple configuration.

According to the sixth aspect of the invention, the cushioning material 90 is provided at the contact portion between the slack pin 8 and the forward movement side contact portion 91 and the backward movement side contact portion 92 of the engagement portion 9. Since it is interposed, it is possible to reduce the impact force of the slack pin 8 on the contact portions 91 and 92 when the displacers 1 and 2 reciprocate, and to prevent the slack pin 8 and the engagement portion 9 from being damaged. .

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a main part of the present invention, showing a state in which it is located at a top dead center.

FIG. 2 is an explanatory view of the same operation, showing a state in which it is located at an intermediate position.

FIG. 3 is an explanatory view of the same operation, showing a state of being located at a bottom dead center.

FIG. 4 is a sectional view showing another embodiment.

FIG. 5 is a diagram showing a performance characteristic with respect to a stroke.

FIG. 6 is a sectional view showing the entire structure of a cryogenic expander.

FIG. 7 is a sectional view showing a conventional example.

[Explanation of symbols]

 1 ... Front displacer 2 ... Rear displacer 4 ... Cylinder 5 ... Long hole 6 ... Pin 60 ... Buffer material 7 ... Joint body 8 ... Slack pin 9 ... Engaging part 90 ... Buffer material 91 ... Forward movement Side contact part 92 ... Return side contact part

Claims (6)

[Claims] 1. A plurality of displacers (1, 2) that reciprocate in a cylinder (4) by supplying and discharging a working fluid.
In a cryogenic expander equipped with, a connecting portion between the front displacer (1) and the rear displacer (2),
A cryogenic expander characterized in that a predetermined play is provided to shorten the reciprocating stroke of the rear displacer (2) with respect to the reciprocating stroke of the former displacer (1). 2. A front displacer (1) and a rear displacer (2) are provided with these displacers (1, 2).
The cryogenic expander according to claim 1, which is connected through a long hole (5) for ensuring the stroke difference and a pin (6) for receiving in the long hole (5). 3. The front displacer (1) and the rear displacer (2) are connected via a joint body (7) which is swingably mounted, and the joint body (7) and the joint body (7). The long hole (5) and the pin (6) between the mounting part of
The cryogenic expander according to claim 2, further comprising: 4. The cryogenic expander according to claim 2 or 3, wherein a cushioning material (60) is provided at a contact locking portion between the elongated hole (5) and the pin (6). . 5. A forward-side contact portion (91) and a backward-side contact portion (9) for abuttingly engaging the front displacer (1) and the rear displacer (2) with the slack pin (8).
2), and the front displacer (1) and the rear displacer (1) are connected between the forward movement side contact portion (91) and the backward movement side contact portion (92). The cryogenic expander according to claim 1, wherein a stroke difference from the displacer (2) is secured. 6. The slack pin (8), and the forward movement side contact portion (91) and the backward movement side contact portion (92) in the engagement portion (9).
The cryogenic expander according to claim 5, wherein a cushioning material (90) is interposed in the abutting portion between and.