CN210532730U

CN210532730U - Pushing piston and low-temperature refrigerator adopting pushing piston

Info

Publication number: CN210532730U
Application number: CN201921167755.5U
Authority: CN
Inventors: 李奥; 董文庆; 钱继峰; 李艳锋
Original assignee: Csic Pride Nanjing Cryogenic Technology Co ltd
Current assignee: Csic Pride Nanjing Cryogenic Technology Co ltd
Priority date: 2019-07-23
Filing date: 2019-07-23
Publication date: 2020-05-15
Anticipated expiration: 2029-07-23

Abstract

The utility model discloses a pass piston and adopt cryocooler of this pass piston belongs to cryocooler technical field, should pass the piston and arrange in cylinder (13) and can be along the extending direction reciprocating motion of cylinder (13), be equipped with sunken helicla flute gas access (4) on the surface of passing the piston, be equipped with the protrusion on the concave wall of helicla flute gas access (4) protruding structure (5) on helicla flute gas access (4) concave wall surface, just protruding structure (5) along the extending direction continuous type of helicla flute gas access (4) sets up or the discrete formula sets up. The low-temperature refrigerator comprises the pushing piston, and the pushing piston is arranged in a cylinder (13) of the low-temperature refrigerator. The utility model discloses a pass the piston can be in limited helicla flute gas passage's size range, let fully carry out the heat exchange between refrigerant gas and the pass piston, reduce cold volume loss to promote the refrigerator performance.

Description

Pushing piston and low-temperature refrigerator adopting pushing piston

Technical Field

The utility model belongs to the technical field of the cryogenic refrigerator technique and specifically relates to a can promote refrigerator performance, reduce the low-temperature refrigerator of the cold volume loss that gas leakage caused between piston and the cylinder lapse piston and adoption this lapse piston.

Background

Examples of the regenerative refrigerator include a GM refrigerator and a stirling refrigerator. These refrigerators have a cylinder and a sliding piston reciprocating inside the cylinder. If the seal between the cylinder and the piston is insufficient, the refrigerant gas may not exhibit the desired cooling capacity. In order to prevent this problem, the refrigerant gas flowing along the spiral groove passes through a longer path than when flowing parallel to the cylinder axis, and therefore can perform sufficient heat exchange with the piston. Therefore, heat loss due to the refrigerant gas flowing through the gap between the cylinder and the piston can be reduced, and a decrease in cooling capacity can be suppressed. However, for a small-sized cryogenic refrigerator, the size of the spiral groove on the piston is limited by the overall structure, the heat exchange area between the refrigerant gas and the piston is limited, and it is difficult to sufficiently cool the refrigerant gas leaked from the hot end of the piston to the cold end to the temperature of the gas in the expansion cavity.

SUMMERY OF THE UTILITY MODEL

The utility model aims at the problem that prior art exists, provide a can promote the refrigerator performance, reduce the thrust piston of the cold volume loss that gas leakage caused between piston and the cylinder and adopt this cryogenic refrigerator who passes the piston.

The utility model aims at solving through the following technical scheme:

the utility model provides a pass piston, this pass piston is arranged in the cylinder and can be along the extending direction reciprocating motion of cylinder, be equipped with sunken helicla flute gas passage on the surface of passing piston which characterized in that: the concave wall of the gas passage of the spiral groove is provided with a convex structure protruding out of the concave wall surface of the gas passage of the spiral groove, and the convex structure is continuously or discretely arranged along the extending direction of the gas passage of the spiral groove.

The size of the outer diameter of an envelope formed by the outer edge of the convex structure is smaller than that of the piston outer diameter of the pushing piston.

The convex structure presents a spiral layout along the extending direction of the spiral groove gas passage.

When the convex structures are arranged continuously, the roots of the convex structures are connected to the bottom diameter of the passage of the spiral groove gas passage.

When the convex structures are arranged in a discrete mode, the roots of the convex structures are connected to the bottom diameter of the gas passage of the spiral groove or the side wall of the concave wall of the gas passage of the spiral groove.

The self-extension direction of the convex structure is parallel to the central axis of the pushing piston, or the self-extension direction of the convex structure and the central axis of the pushing piston form an inclination angle.

When the pushing piston is in a multi-stage structure, the convex structure is positioned on the pushing piston behind the primary pushing piston.

A cryocooler using the push piston is characterized in that: the low-temperature refrigerator comprises the pushing piston, and the pushing piston is arranged in a cylinder of the low-temperature refrigerator.

When the low-temperature refrigerator adopts a multi-stage cylinder, the pushing piston is arranged in the cylinder behind the primary cylinder.

When the low-temperature refrigerator adopts a single-stage cylinder, the pushing piston is arranged in the cylinder.

Compared with the prior art, the utility model has the following advantages:

the utility model discloses a be equipped with the protrusion on helicla flute gas access's concave wall the protruding structure on helicla flute gas access concave wall surface, just protruding structure along helicla flute gas access's extending direction continuous type sets up or the discrete setting for the lapse piston is in limited helicla flute gas access's size range, lets fully carry out the heat exchange between refrigerant gas and the lapse piston, reduces the cold volume loss that gas leakage caused between piston and the cylinder, prevents that the refrigerating capacity from descending, and promotes the refrigerator performance.

Drawings

Fig. 1 is a schematic front structural view of a push piston of the present invention having a discretely arranged convex structure;

FIG. 2 is a schematic view of the cross-sectional structure A-A of FIG. 1;

fig. 3 is a schematic front structural view of the pushing piston of the present invention with a discretely arranged convex structure;

FIG. 4 is a schematic structural view of a section B-B in FIG. 3;

fig. 5 is a schematic structural view of an embodiment of the push piston of the present invention installed on a cryocooler.

Wherein: 1-a compressor; 2-a cover assembly; 3-gas line; 4-spiral groove gas passage; 5, a convex structure; 5 a-via bottom diameter; 5 b-a cavity; 5 c-envelope outside diameter; 6, an annular groove; 7-piston seal ring; 8-a thermal chamber; 9-primary expansion chamber; 10-a secondary expansion chamber; 11-first stage pushing piston; 11 a-primary piston front hole; 11 b-first stage piston rear hole; 11 c-primary cool storage material; 12-a two-stage pushing piston; 12 a-secondary piston front hole; 12 b-exhaust port; 12 c-secondary cool storage material; 12 d-piston outside diameter; 13-a cylinder; 131-a first-stage cylinder; 132-a secondary cylinder; 13 a-primary heat exchanger; 13b — secondary heat exchanger.

Detailed Description

The present invention will be further described with reference to the accompanying drawings and examples.

As shown in fig. 1-5: a push piston which is provided in a cylinder 13 and is capable of reciprocating in an extending direction of the cylinder 13, and which is formed in a cylindrical shape and has a cold storage material therein, thereby expanding a compressed working fluid in the cylinder 13 to generate cold; be equipped with sunken helicla flute gas access 4 on advancing the surface of piston, be equipped with the protrusion on the concave wall of helicla flute gas access 4 the protruding structure 5 on the concave wall surface of helicla flute gas access 4, just protruding structure 5 is along the extending direction continuous type setting or the setting of dispersion of helicla flute gas access 4. The outer diameter 5c of the envelope formed by the outer edge of the convex structure 5 is smaller than the outer diameter 12d of the piston of the pushing piston so as to avoid direct contact with the inner surface of the cylinder 13 and abrasion, and the outer peripheral surface of the pushing piston is coated with a wear-resistant resin material.

In the above structure, the projection structure 5 exhibits a spiral layout along the extending direction of the spiral groove gas passage 4. When the projection structure 5 is provided continuously, the root of the projection structure 5 is connected to the passage bottom diameter 5a of the spiral groove gas passage 4. When the convex structures 5 are arranged in a discrete manner, the roots of the convex structures 5 are connected to the passage bottom diameter 5a of the spiral groove gas passage 4 or the concave wall side wall of the spiral groove gas passage 4; in this case, the direction of self-extension of the projection 5 is parallel to the central axis of the displacement piston, or the direction of self-extension of the projection 5 forms an angle of inclination with the central axis of the displacement piston.

When the pushing piston is a multi-stage structure, the convex structure 5 is located on the pushing piston behind the primary pushing piston.

A cryocooler adopting the pushing piston comprises the pushing piston, and the pushing piston is arranged in a cylinder 13 of the cryocooler. When the low-temperature refrigerator adopts the multi-stage cylinder 13, the pushing piston is arranged in the cylinder 13 behind the primary cylinder 13; if the cryocooler employs a dual stage cylinder 13, the above-described pusher piston is mounted within the secondary cylinder 132. When the low-temperature refrigerator adopts a single-stage cylinder 13, the pushing piston is arranged in the cylinder 13. The low-temperature refrigerator is any type of refrigerator with a reciprocating moving piston, and is not limited to gifford-mcmahon refrigerators, solvin refrigerators, pulse tube refrigerators and the like.

As shown in fig. 1: the low-temperature refrigerator comprises a compressor 1, a cover body component 2, a gas pipeline 3, a cylinder 13, a first-stage pushing piston 11 and a second-stage pushing piston 12. The compressor 1 sucks and compresses a refrigerant gas to discharge the refrigerant gas as a high-pressure refrigerant gas. The gas pipe 3 supplies the high-pressure refrigerant gas to the cover unit 2. The cylinder 13 is a two-stage cylinder, the body is made of 304 stainless steel, the first-stage cylinder body 131 and the second-stage cylinder body 132 are coaxially arranged, and the inner diameter of the second-stage cylinder body 132 is smaller than that of the first-stage cylinder body 131; a primary heat exchanger 13a is welded to one end (cold end) of the primary cylinder 131 far away from the cover body assembly 2, and a secondary heat exchanger 13 is welded to one end (cold end) of the secondary cylinder 132 far away from the cover body assembly 2, and the heat exchangers are all made of copper. A first-stage pushing piston 11 is arranged in the first-stage cylinder body 131, a second-stage pushing piston 12 is arranged in the second-stage cylinder body 132, the first-stage pushing piston 11 and the second-stage pushing piston 12 are coaxially connected, and are driven by a driving mechanism (not shown in the figure) to move together along the directions Z1-Z2 in the cylinder 13. When secondary pushing piston 12 moves upward in the figure (direction Z1), the volumes of primary expansion chamber 9 and secondary expansion chamber 10 increase; conversely, the corresponding expansion volume becomes smaller. Under the change of the volume of the expansion cavity, the refrigerant gas flowing in carries out heat exchange with the primary cold storage material 11c in the primary pushing piston 11 through the primary piston front hole 11a, and then flows out to the primary expansion cavity 9 from the primary piston rear hole 11 b; part of gas expands in the primary expansion cavity 9, the rest gas flows into the secondary pushing piston 12 through the secondary piston front hole 12a, exchanges heat with the secondary cold storage material 12c inside the secondary pushing piston 12, then flows out from the exhaust port 12b on the annular groove 6, and enters the secondary expansion cavity 10, the refrigerant gas transfers the heat of the refrigerant gas to the cold storage material in the process, and the temperature is changed from normal temperature to low temperature. Along the gas flow direction, i.e., the direction Z2, the temperatures of cylinder 13, primary thrust piston 11, and secondary thrust piston 12 continuously decrease, forming a temperature gradient.

As shown in fig. 1: the backflow gas is opposite to the flowing process, the refrigerant gas flows out of the secondary expansion cavity 10, exchanges heat with the secondary cold storage material 12c in the secondary pushing piston 12 through the exhaust port 12b, flows out of the front hole 12a of the secondary piston, is mixed with the refrigerant gas in the primary expansion cavity 9, exchanges heat with the primary cold storage material 11c in the primary pushing piston 11 through the rear hole 11b of the primary piston, enters the cover body assembly 2 through the front hole 11a of the primary piston, and then flows to the low-pressure side of the compressor 1. In the process, the refrigerant gas absorbs heat from the cold storage material, and the temperature is changed from low temperature to normal temperature.

By repeating the above operations, the primary regenerator material 11c, the secondary regenerator material 12c, and the refrigerant gas are cooled. The low-temperature gas continuously expands and does work in the first-stage expansion cavity 9 and the second-stage expansion cavity 10 to form a refrigeration source. The primary heat exchanger 13a and the secondary heat exchanger 13b are cooled by the heat transfer effect.

The primary pushing piston 11 is sealed by a piston seal ring 7 in a gap between its outer peripheral surface and the inner wall of the primary cylinder 131 of the cylinder 13. Because piston seal ring 7 is installed on room temperature one side, be close to cover body subassembly 2 one side, so in the operation process, the temperature is moderate and is in a higher temperature, can effectively prevent that refrigerant gas from getting into first order expansion chamber 9 through the clearance between first order push piston 11 outer surface and the first order cylinder body 131 inner wall. The temperature of the primary heat exchanger 13a is in a temperature zone of 40K-80K approximately.

As shown in fig. 1 to 4, the following describes the push piston 12 of the present invention in detail by taking the two-stage push piston as an example.

A clearance of 5 μm to 50 μm is generally provided between the secondary pushing piston 12 and the inner wall of the secondary cylinder 132. In order to effectively prevent refrigerant gas from entering the secondary expansion cavity 10 through the gap between the secondary pushing piston 12 and the secondary cylinder 132 in parallel, a concave spiral groove gas passage 4 is formed on the surface of the secondary pushing piston 12 to increase the flow of the refrigerant gas, and high-temperature gas leaked into the gap from the hot end of the pushing piston 12 is cooled to the gas temperature in the secondary expansion cavity 10 through the temperature gradient of the pushing piston 12, so that the gas with higher enthalpy value and flowing into the expansion cavity from the gap in series is cooled to low enthalpy value gas, and the extra cold loss is reduced. The length of the spiral groove gas passage 4 is limited by the size of the secondary pushing piston 12, which cannot be made very long, and the heat exchange with the refrigerant gas passing through the passage cannot be sufficiently performed, which will cause the loss of cooling capacity.

Two constructive ways that are easy to implement are proposed below to avoid the above-mentioned drawbacks.

As shown in fig. 1-2, the protruded structure 5 protruding from the concave wall surface of the spiral groove gas passage 4 is formed on the concave wall surface of the spiral groove gas passage 4, the root of the protruded structure 5 is preferably connected to the passage bottom diameter 5a of the spiral groove gas passage 4, the protruded structures 5 are arranged in a continuous manner or a discrete manner, any one protruded structure 5 is not connected with other protruded structures 5, a concave cavity 5b is formed between adjacent protruded structures 5, and the protruded structures 5 themselves extend along a direction generally parallel to the axial direction of the piston 12 and are arranged in the corresponding cross-section groove of the spiral groove gas passage 4. When gas flows through the spiral groove gas passage 4, the size of the envelope outer diameter 5c of the convex structure 5 is smaller than the size of the piston outer diameter 12d, so that the clearance between the envelope outer diameter 5c of the convex structure 5 and the inner surface of the secondary cylinder 132 is far larger than the clearance between the piston outer diameter 12d of the secondary pushing piston 12 and the inner surface of the secondary cylinder 132, the gas can flow through the path, but when flowing, the gas can impact the convex structure 5 in the front direction, vortex turbulence is formed between two adjacent convex structures 5, a 'tube-fin heat exchanger' structure is formed, the heat exchange time between the gas and the secondary pushing piston 12 is prolonged, and the heat exchange is more sufficient.

In the preparation process of the structure, the spiral groove gas passage 4 can be machined on the secondary pushing piston 12, and then the spiral knurling tool is adopted to extrude the spiral groove gas passage 4 along the path of the spiral groove gas passage to form the structure. In the processing process, a parallel thread knurling mode can be adopted, and the self extending direction of the pressed convex structure 5 is parallel to the central main shaft of the secondary pushing piston 12; or the extrusion can be carried out by adopting an oblique thread knurling mode, so that the self extending direction of the convex structure 5 forms an inclination angle with the central main shaft of the secondary pushing piston 12.

Further, the structure shown in fig. 3 to 4 may be employed. Specifically, unlike the configuration shown in fig. 1-2, the root of the projection structure 5 is connected to the passage bottom diameter 5a of the spiral groove gas passage 4 and continuously extends along the spiral groove gas passage 4, and becomes a continuous spiral fin structure, and the envelope outer diameter 5c is smaller than the piston outer diameter 12d in order to prevent wear of the cylinder. When the refrigerant gas flows through the spiral groove gas passage 4, the convex structure 5 extends continuously and is parallel to the flow direction of the gas flow, but the contact area of the gas and the spiral groove gas passage 4 is increased, and the heat exchange effect is increased. In the above structure preparation process, two cutters arranged in parallel can be adopted to simultaneously process along the extension path of the spiral groove gas passage 4.

It should be noted that, in the present invention, the root of the protruding structure 5 is connected to the path bottom diameter 5a of the spiral groove gas path 4, and certainly, the protruding structure may also protrude from other positions on the groove surface of the spiral groove gas path 4, which is not limited to the embodiment of the present invention.

The utility model discloses a be equipped with the protrusion on the concave wall of helicla flute gas passage 4 the protruding structure 5 on the 4 concave wall surfaces of helicla flute gas passage, just protruding structure 5 along the extension direction continuous type of helicla flute gas passage 4 sets up or the discrete formula sets up for the push piston in limited helicla flute gas passage 4's size range, let refrigerant gas and push piston between fully carry out the heat exchange, reduce the cold volume loss that gas leakage caused between piston and the cylinder, prevent that the refrigerating capacity from descending, and promote the refrigerator performance.

The above embodiments are only for explaining the technical idea of the present invention, and the protection scope of the present invention cannot be limited thereby, and any modification made on the basis of the technical scheme according to the technical idea provided by the present invention all fall within the protection scope of the present invention; the technology not related to the utility model can be realized by the prior art.

Claims

1. A push piston, this push piston is placed in cylinder (13) and can be along the reciprocating motion of cylinder (13) extending direction, be equipped with sunken helicla flute gas passage (4) on push piston's the surface, its characterized in that: be equipped with the protrusion on the concave wall of helicla flute gas passage (4) protruding structure (5) on helicla flute gas passage (4) concave wall surface, just protruding structure (5) are followed the extending direction continuous type of helicla flute gas passage (4) sets up or the discrete formula sets up.

2. A pushing piston according to claim 1, characterized in that: the size of an envelope outer diameter (5 c) formed by the outer edge of the convex structure (5) is smaller than the size of a piston outer diameter (12 d) of the pushing piston.

3. A pushing piston according to claim 1, characterized in that: the convex structures (5) present a spiral arrangement along the extension direction of the spiral groove gas passage (4).

4. A pushing piston according to claim 1, characterized in that: when the convex structures (5) are arranged continuously, the roots of the convex structures (5) are connected to the passage bottom diameter (5 a) of the spiral groove gas passage (4).

5. A pushing piston according to claim 1, characterized in that: when the protruding structures (5) are arranged in a discrete mode, the roots of the protruding structures (5) are connected to the bottom diameter (5 a) of the spiral groove gas passage (4) or the side wall of the concave wall of the spiral groove gas passage (4).

6. Advancing piston according to claim 5, characterized in that: the self-extension direction of the convex structure (5) is parallel to the central axis of the pushing piston, or the self-extension direction of the convex structure (5) and the central axis of the pushing piston form an inclination angle.

7. A pushing piston according to claim 1, characterized in that: when the pushing piston is of a multi-stage structure, the convex structure (5) is positioned on the pushing piston behind the primary pushing piston.

8. A cryocooler using a sliding piston according to any of claims 1 to 7, characterized in that: the low-temperature refrigerator comprises the pushing piston, and the pushing piston is arranged in a cylinder (13) of the low-temperature refrigerator.

9. The cryocooler of claim 8, wherein: when the low-temperature refrigerator adopts a multi-stage cylinder (13), the pushing piston is arranged in the cylinder (13) behind the primary cylinder (13).

10. The cryocooler of claim 8, wherein: when the low-temperature refrigerator adopts a single-stage cylinder (13), the pushing piston is arranged in the cylinder (13).