CN212657904U - Cold storage type refrigerator capable of inhibiting horizontal performance attenuation - Google Patents

Abstract

The utility model discloses a cold storage type refrigerator for inhibiting horizontal performance attenuation, including cylinder (13) and push piston, clearance (122 a) between the outer peripheral face of the piston cylinder (121) of push piston and the inner peripheral face of cylinder (13) constitutes second gas passage (122) that refrigerant gas flows, and second gas passage (122) and exhaust hole (12 b) intercommunication, the low temperature side of second gas passage (122) is equipped with cushion chamber (125), radial projection distance d2 of this cushion chamber (125) along the direction perpendicular to push piston axial direction is greater than the biggest radial projection distance d1 of second gas passage (122) perpendicular to push piston axial; and the buffer cavity (125) is far away from the cold end of the cylinder (13) than the exhaust hole (12 b) on the axial position of the pushing piston. The utility model discloses when the cushion chamber that sets up can operate the refrigerator under non-vertical state, effectively restrain the decay of refrigeration performance.

Description

Cold storage type refrigerator capable of inhibiting horizontal performance attenuation

Technical Field

The utility model belongs to the technical field of the cryogenic refrigerator, specifically speaking is a performance decay's cold-storage refrigerator when can restrain refrigerator horizontal movement.

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.

Along with the reduction of the refrigeration temperature, the temperature of the cold end of the refrigerator is gradually reduced to be below a 20K temperature zone from the room temperature of 300K. From the change in the gas density of the refrigerant (helium gas) shown in fig. 8, the density of helium gas sharply increases below the 15K temperature range, and liquid phase helium is formed at the 4K temperature range.

Generally, the diameter of the outer peripheral surface of the moving piston is slightly smaller than that of the inner peripheral surface of the cylinder, and a second gas passage through which refrigerant gas flows is formed. The refrigerator is operated in a vertically downward mode in the operation process, such as the direction shown in fig. 1 and 2. The refrigerant gas forms a gradient distribution of temperature, i.e. the upper end in fig. 1 is high-temperature gas with low density, the lower end is low-temperature gas with high density, and the state is a stable state under the influence of gravity, which is beneficial to the operation of the refrigerator.

However, once the refrigerator is operated in a horizontal position (in a vertical direction as shown in fig. 1), a stable temperature distribution cannot be formed in the second gas passage by the porous effect like the refrigerant gas flowing through the regenerator material. Because the density of helium at the low-temperature end is far greater than that of helium at the temperature above 15K, air flows at the cold and hot ends in the long and narrow second gas channel are mixed with each other, and the influence is more severe along with the increase of the annular cross section area of the channel, so that the performance of the refrigerating machine is attenuated, and a refrigerating machine performance comparison table which changes along with the increase of a secondary pushing piston of the refrigerating machine is given in table 1.

Vertical performance	[email protected]	[email protected]	[email protected]
				Horizontal performance	[email protected]	[email protected]	[email protected]
Rate of decay	10%	20%	32%

TABLE 1 comparison of the performances of a refrigerator having different secondary thrust pistons, in the vertical and in the horizontal conditions

This phenomenon will limit the practical application of the refrigerator and will be restricted in the way the refrigerator is installed.

SUMMERY OF THE UTILITY MODEL

The utility model aims to provide a cold storage type refrigerator which can restrain the attenuation of horizontal performance aiming at the problems existing in the prior art; the regenerative refrigerator can suppress performance degradation during horizontal operation of the refrigerator.

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

a regenerative refrigerator for suppressing horizontal performance degradation, comprising a cylinder, a push piston disposed in the cylinder and reciprocating in the axial direction of the cylinder, wherein a gap between the outer circumferential surface of a piston cylinder of the push piston and the inner circumferential surface of the cylinder forms a second gas passage through which refrigerant gas flows, and the second gas passage can communicate with a gas discharge hole of the push piston, characterized in that: a buffer cavity is arranged on the low-temperature side of the second gas channel, and the radial projection distance d2 of the buffer cavity along the direction vertical to the axial direction of the pushing piston is greater than the maximum radial projection distance d1 of the second gas channel vertical to the axial direction of the pushing piston; and the buffer cavity is far away from the cold end of the cylinder than the exhaust hole in the axial position of the pushing piston.

The buffer cavity is distributed at the axial position of a temperature range below 15K in the axial direction of the pushing piston.

The buffer cavity is distributed at the axial position of a 5-10K temperature zone of the axial temperature distribution of the pushing piston.

The pushing piston is internally provided with cold storage materials for cooling or heating refrigerant gas, and gaps among the cold storage materials are formed into a first gas channel for flowing the refrigerant gas; the first gas passage is not in direct communication with the buffer chamber.

The buffer cavity is arranged on the outer peripheral surface of the piston cylinder body and/or the inner peripheral surface of the cylinder.

The buffer cavity is an annular groove or a radial air hole.

The buffer cavity forms a pit for slowing down the flowing speed of refrigerant gas on the outer circumferential surface of the piston cylinder and/or the inner circumferential surface of the cylinder.

The second gas channel is in a spiral groove structure, or a labyrinth seal structure, or a gap seal structure which is parallel to the axial direction of the pushing piston and is along the inner circumferential surface of the cylinder.

When the cold storage type refrigerating machine adopts two-stage refrigeration, the second gas channel is communicated with the first-stage expansion cavity and the second-stage expansion cavity, and the buffer cavity is positioned in the second-stage cylinder body.

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

the utility model discloses a cold-storage refrigerator passes through the setting of cushion chamber, and the refrigerator can effectively restrain the decay of refrigerator refrigeration performance when the operation under non-vertical state.

Drawings

Fig. 1 is a schematic structural view of an embodiment of a regenerative refrigerator for suppressing horizontal performance degradation according to the present invention;

FIG. 2 is a schematic diagram of a push piston portion of a prior art cryocooler;

fig. 3 is one of the schematic structural diagrams of the push piston part of the regenerative refrigerator according to the present invention;

FIG. 4 is a schematic structural view of a section A-A of FIG. 3 when the buffer chamber is an annular groove;

FIG. 5 is a schematic structural view of a section A-A of FIG. 3 when the buffer chamber is a radial air hole;

fig. 6 is a second schematic structural view of a push piston portion of a regenerative refrigerator according to the present invention;

FIG. 7 is a schematic structural view of a section B-B in FIG. 6 when the buffer chamber is an annular groove;

FIG. 8 is a graph of density change for helium at three pressures;

fig. 9 is a comparison diagram of the effect of the regenerative refrigerator provided by the present invention after implementation;

fig. 10 shows the effect of the long-term horizontal operation of the regenerative refrigerator according to the present invention.

Wherein: 1-a compressor; 2-a cover assembly; 3-gas line; 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-vent hole; 12 c-secondary cool storage material; 13-a cylinder; 131-a first-stage cylinder; 132-a secondary cylinder; 13 a-primary heat exchanger; 13 b-a secondary heat exchanger; 121-piston cylinder; 122 — second gas channel; 122a — a gap; 123-cryogenic channel; 124-felt or wire mesh; 125 — buffer chamber.

Detailed Description

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

As shown in fig. 1: 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 13b 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 fig. 1) to move together along the directions of 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; a 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 hole 12b, and enters the secondary expansion cavity 10, the refrigerant gas transfers the heat of the refrigerant gas to the cold storage material, 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 hole 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.

According to different temperature zones, the secondary cold storage material 12c is generally made of lead, zinc, tin and bismuth as heat exchange materials at the high-temperature side; and a magnetic cold storage material holmium copper is adopted near the low-temperature side. The selected material has larger specific heat of volume in a corresponding temperature area, the cold storage material can form stable temperature at the same height position of the pushing piston in the process of feeding and refluxing, and the temperature is almost kept unchanged and only gradually reduced along the axial direction in the process of carrying out heat exchange with gas. Therefore, the cold storage material in the piston is pushed to form a stable and continuous temperature gradient, and in the air inlet process, the airflow is gradually cooled by the cold storage material and enters the expansion cavity to carry out expansion refrigeration; in the process of backflow, the gas is heated by the cold storage material step by step and finally enters the low-pressure cavity of the compressor to complete a cycle.

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 the piston sealing ring 7 is arranged on one side of room temperature, namely one side close to the cover body component 2, the temperature is always at a higher temperature; therefore, during operation, the refrigerant gas can be effectively prevented from entering the primary expansion chamber 9 through the gap between the outer surface of the primary push piston 11 and the inner wall of the primary cylinder 131. The temperature of the primary heat exchanger 13a is in a temperature zone of 40K-80K approximately.

The second-stage pushing piston 12 is taken as an example, and the conventional regenerative refrigerator in the prior art is combined to describe the regenerative refrigerator provided by the present invention in detail.

For a two-stage refrigerator, the whole of the two-stage pushing piston 12 is in a low temperature condition, and cannot be sealed in a sealing ring mode, and a spiral groove or labyrinth sealing mode is generally adopted.

In the push piston portion of the conventional regenerative refrigerator of the related art as shown in fig. 2, a gap 122a of 0.01 to 0.03mm is formed between the outer circumferential surface of the piston cylinder 121 and the inner circumferential surface of the secondary cylinder 132, and a second gas passage 122 communicating the primary expansion chamber 9 and the secondary expansion chamber 10 is formed with a spiral groove having a width of about 2mm, a depth of about 0.6mm, and a distance of about 4 mm. In this way, compared to the case where the secondary cylinder 132 flows in parallel in the axial direction, the gas flow path through which the gas leaks from the gap 122a between the secondary cylinder 132 and the secondary pushing piston 12 is increased, and the heat exchange between the leaked gas and the outer peripheral surface of the secondary pushing piston 12 is more sufficient. The cold storage material 12c is made of granular lead pills or magnetic material holmium copper, and is separated from the exhaust hole 12b at the cold end through a felt or a silk screen 124, so that the granular secondary cold storage material 12c is prevented from being exposed in the operation process. The exhaust holes 12b are uniformly distributed in the radial direction, the inner side of the exhaust hole 12b is communicated with the low-temperature channel 123 and is hermetically communicated with the secondary cold storage material 12c, and the outer side of the exhaust hole 12b is in gas communication with the second gas channel 122.

For the low-temperature refrigerator below the 20K temperature zone, and further below the 15K temperature zone, the density of helium is sharply increased below 15K. When the refrigerator is vertically installed and operated, helium gas is low in temperature and high in density and is positioned at the lower end; helium gas has high temperature and small density, is positioned at the upper end, is influenced by gravity, is in a stable state, and is beneficial to the stability of the refrigerating machine. When the refrigerator is in a non-vertical state, helium in the second gas channel 122 cannot form stable temperature and density gradient distribution, and particularly, in a horizontal state, high-temperature gas and low-temperature gas in the second gas channel 122 are influenced by gravity and can be mixed with each other to transfer heat at the hot end to the low-temperature end, so that cold loss is caused. In particular, the larger the piston, the larger the cross-sectional area of the second gas passage 122 along the axis, the greater the effect

In order to avoid the above problems, the utility model discloses reform on the traditional structure that fig. 2 shows, the concrete way is: on the low temperature side of the second gas passage 122 communicating the primary expansion chamber 9 and the secondary expansion chamber 10, a cushion chamber 125 is formed to expand in the direction intersecting the axis along the circumferential direction of the secondary cylinder 132 or the secondary thrust piston 12 in a temperature region having a temperature distribution of 15K or less, and is axially closer to the high temperature side than the exhaust hole 12 b. The buffer chamber 125 has an effect of making the flow rate of the refrigerant gas flowing through the second gas passage 122 slower. The radial projection distance d2 of the buffer chamber 125 in the radial direction perpendicular to the axial direction of the sliding piston and the maximum radial projection distance d1 of the second gas passage 122 in the radial direction satisfy d2/d1 > 1.

Further, taking a 4K cryocooler as an example, the temperature region of the layout of the buffer chamber 125 is about 5-10K, when the refrigerant discharged through the exhaust hole 12b enters the secondary expansion chamber 10, the refrigerant enters the supercritical state, and the density of the refrigerant is far less than that of the refrigerant in the above state relative to the density of the higher temperature side in the axial direction of the exhaust hole 12 b. The radial projection distance d2 of the buffer chamber 125 is greater than the maximum radial projection distance d1 of the second gas passage 122, and when the refrigerator is not vertically placed, especially horizontally placed, and the refrigerant flows through the buffer chamber 125, the buffer chamber 125 will form a "pit" on the outer peripheral surface of the secondary pushing piston 12, and the gas flow rate becomes abnormally slow, even a "blocking" phenomenon is formed, so that the buffer chamber 125 has an isolation effect on a certain level, so that the low-density gas flow on the high-temperature side of the second gas passage 122 is separated from the high-density gas flow on the low-temperature side. In the non-vertical operation state of the refrigerator, the influence of gravity on the gradient distribution of the air flow density is reduced, so that a large amount of hot end air flow and low temperature air flow are prevented from being mixed, and the performance attenuation of the refrigerator is reduced.

The utility model discloses in provide following several kinds of embodiments.

The first embodiment is as follows:

as shown in fig. 3 and 4, the outer peripheral surface of secondary thrust piston 12 has a spiral groove structure (or a clearance seal structure, such as the clearance structure between secondary thrust piston 12 and secondary cylinder 132 shown in fig. 6) to form second gas passage 122. An annular buffer chamber 125 is formed at the low temperature end of the secondary thrust piston 12 along the circumferential direction of the low temperature end of the secondary thrust piston 12, and is disposed on the high temperature side with respect to the exhaust hole 12b as shown in fig. 4 in cross section. The radial projection distance d2 of the annular buffer chamber 125 is greater than the maximum radial projection distance d1 of the spiral second gas channel 122 (i.e., the distance from the bottom diameter of the spiral groove to the inner circumferential surface of the secondary cylinder 132), and the "concave pit" is formed. In the above-described manner, the buffer chamber 125 is not communicated with the low temperature path 123, and the flow of the air inside the secondary push piston 12 is prevented from flowing out of the buffer chamber 125.

Embodiment two:

as shown in fig. 3 and 5, the outer peripheral surface of secondary thrust piston 12 has a spiral groove structure (or a clearance seal structure, such as a clearance structure between secondary thrust piston 12 and secondary cylinder 132 shown in fig. 6), and clearance 122a forms second gas passage 122. At the low temperature end of the secondary push piston 12, radial air holes arranged in a radial direction may be formed along the outer circumferential surface of the secondary push piston 12 as the buffer chamber 125, and as shown in fig. 5, a radial projection distance d2 of the radial air hole-shaped buffer chamber 125 is greater than a maximum radial projection distance d1 of the spiral second air passage 122, so that the "pits" are formed. In the above-described manner, the buffer chamber 125 is not communicated with the low temperature path 123, and the flow of the air inside the secondary push piston 12 is prevented from flowing out of the buffer chamber 125.

The third embodiment is as follows:

as shown in fig. 6 and 7, an annular gap seal structure (spiral groove structure form shown in fig. 3 may be adopted) is formed between the outer peripheral surface of the secondary pushing piston 12 and the secondary cylinder 132, and the gap 122a forms the second gas passage 122. An annular buffer chamber 125 is formed at a low temperature end of the inner peripheral surface of the secondary cylinder 132 (the annular buffer chamber 125 may be formed at the inner peripheral surface of the secondary heat exchanger 13b at a corresponding position as needed), and is arranged in a temperature range of the axial temperature of 15K or less. Further, during the up-and-down reciprocating movement of the two-stage pushing piston 12, the exhaust hole 12b is always located at a lower temperature side with respect to the cushion chamber 125 in the axial direction.

The implementation effect is as follows:

as shown in fig. 9. The test prototype adopts a 2.5W @4.2K low-temperature refrigerator to carry out performance test in a vertical state. Under the condition of no load, the lowest temperature reaches 2.4K, and the refrigerating capacity reaches 2.5W at the temperature of 4.2K. And then horizontally placing the refrigerating machine for comparison test. When the traditional structure (shown in figure 2) is used for testing, the performance of the refrigerating machine is greatly attenuated under the influence of gravity, the lowest temperature without load is changed to 2.8K, the refrigerating capacity at the temperature of 4.2K is changed to 1.7K, and the relative attenuation rate of the performance is 32%. When the technology is adopted for implementation, the lowest temperature of no load is tested to be 2.55K under the horizontal condition, the refrigerating capacity is 2.2W under the temperature of 4.2K, the relative attenuation rate is 12%, the performance attenuation is obviously inhibited, and after the time continuously exceeds 500h, the secondary performance of the refrigerating machine is still in a stable state, and the effect is shown in figure 10.

The utility model discloses a cold-storage refrigerator passes through the setting of cushion chamber 125, and the refrigerator can effectively restrain the decay of refrigerator refrigeration performance when the operation under non-vertical state.

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 (9)

1. A regenerative refrigerator for suppressing horizontal performance degradation, comprising a cylinder (13), a pusher piston disposed inside the cylinder (13) and reciprocating in the axial direction of the cylinder (13), wherein a gap (122 a) between the outer peripheral surface of a piston cylinder (121) of the pusher piston and the inner peripheral surface of the cylinder (13) constitutes a second gas passage (122) through which refrigerant gas flows, and the second gas passage (122) is capable of communicating with a gas discharge hole (12 b) of the pusher piston, characterized in that: a buffer cavity (125) is arranged on the low-temperature side of the second gas channel (122), and the radial projection distance d2 of the buffer cavity (125) along the direction vertical to the axial direction of the pushing piston is larger than the maximum radial projection distance d1 of the second gas channel (122) vertical to the axial direction of the pushing piston; and the buffer cavity (125) is far away from the cold end of the cylinder (13) than the exhaust hole (12 b) on the axial position of the pushing piston.

2. The regenerative refrigerator according to claim 1, wherein the regenerative refrigerator includes: the buffer chamber (125) is distributed at the axial position of the temperature range below 15K in the axial direction of the pushing piston.

3. The regenerative refrigerator suppressing the level performance deterioration according to claim 1 or 2, characterized in that: the buffer cavity (125) is distributed at the axial position of a 5-10K temperature zone of axial temperature distribution of the pushing piston.

4. The regenerative refrigerator according to claim 1, wherein the regenerative refrigerator includes: the pushing piston is internally provided with cold storage materials for cooling or heating refrigerant gas, and gaps among the cold storage materials are formed into a first gas channel for flowing the refrigerant gas; the first gas passage is not in direct communication with the buffer chamber (125).

5. The regenerative refrigerator according to claim 1, wherein the regenerative refrigerator includes: the buffer cavity (125) is arranged on the outer circumferential surface of the piston cylinder body (121) and/or the inner circumferential surface of the cylinder (13).

6. The regenerative refrigerator suppressing a level performance deterioration according to claim 1 or 5, characterized in that: the buffer cavity (125) is an annular groove or a radial air hole.

7. The regenerative refrigerator suppressing a level performance deterioration according to claim 1 or 5, characterized in that: the buffer cavity (125) forms a pit for slowing down the flowing speed of refrigerant gas on the outer circumferential surface of the piston cylinder body (121) and/or the inner circumferential surface of the cylinder (13).

8. The regenerative refrigerator according to claim 1, wherein the regenerative refrigerator includes: the second gas channel (122) is in a spiral groove structure, a labyrinth seal structure or a clearance seal structure which is parallel to the axial direction of the pushing piston and is along the inner circumferential surface of the cylinder (13).

9. The regenerative refrigerator according to claim 1, wherein the regenerative refrigerator includes: when the cold accumulation type refrigerating machine adopts double-stage refrigeration, the second gas channel (122) is communicated with the first-stage expansion cavity (9) and the second-stage expansion cavity (10), and the buffer cavity (125) is positioned in the second-stage cylinder body (132).

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