CN102519178B - Free piston expander - Google Patents

Abstract

The invention relates to a free piston expander, which belongs to the field of low temperature refrigeration. The expander includes a plate spring, a gap sealing seat, a regenerator, a cold finger, a cold cylinder, a drive rod, an end cover, a joint pipe and a peripheral equipment compressor; One or more leaf springs, the center of the leaf spring has a hole, and the two ends are fixed on the cold cylinder; the regenerator is located in the cold finger, and the regenerator is filled with wire woven square mesh; the front end of the regenerator is equipped with a drive Rod, the driving rod extends into the cold cylinder, passes through the center of the leaf spring and is fixedly connected with the center of the leaf spring; the gap seal seat is located at the communication place between the cold cylinder and the inner cavity of the cold finger. The plate spring is used to play the role of rigid support, and there is no driving motor in the cold cylinder, which reduces energy consumption.

Description

A free piston expander

technical field

The invention relates to a free piston expander, which belongs to the field of low temperature refrigeration.

Background technique

Due to its many advantages, the Stirling refrigerator is currently widely used in space and on the ground, especially in imaging systems such as space infrared, which have high requirements on the vibration and life of the Stirling refrigerator, and its life index has generally reached Years. As shown in Figure 1, a Stirling refrigerator includes a compressor, an expander, and an intermediate pipe. During operation, the compressor generates periodically changing pressure waves, which are transmitted to the expander through the intermediate pipe to push the return in the expander. The heater reciprocates periodically, and generates refrigeration capacity in the cold chamber during the isothermal expansion process of the working medium gas movement in the chamber. The motion phase between the pressure wave and the regenerator is a key parameter. Generally, the drive of the regenerator uses a motor, and the support is supported by a cylindrical spring. The phase adjustment of the regenerator uses the drive motor and spring stiffness.

Contents of the invention

The purpose of the present invention is to provide a free-piston expander, which realizes the non-abrasive gap seal of the Stirling refrigerator, the pure gas drive without motor, and the flexible plate spring support technology, and ensures the high temperature of the regenerator in the expander when it is working. Reliable, low vibration output.

To achieve the above object, the technical scheme of the present invention is as follows:

A free-piston expander, the expander includes: a leaf spring, a gap seal seat, a regenerator, a cold finger, a cold cylinder, a drive rod, an end cover, a union pipe, and a peripheral equipment compressor;

The cold cylinder and the cold finger are both cylindrical cavity structures, the diameter of the cold finger is 1/5 to 1/3 of the cold cylinder, the cold cylinder and the cold finger are integrated, one end of the cold cylinder is fixedly connected The cavity is connected, and the other end of the cold cylinder is welded with an end cover. The cold cylinder and the end cover form a back pressure chamber. In the back pressure chamber, one or more leaf springs are placed along the longitudinal axis of the cold cylinder. The center of the leaf spring has a hole, and the two ends fixed on the cold cylinder;

The regenerator is located in the cold finger, and the other end of the cold finger and the rear end of the regenerator form a cold cavity; the regenerator is filled with wire woven square mesh, and one or more through holes are opened at the front end of the regenerator. The through holes communicate with the metal wire braided square hole net, and one or more through holes are opened at the rear end of the regenerator, and the through holes make the metal wire braided square hole net communicate with the cold chamber;

The front end of the regenerator is provided with a driving rod, and the through holes on the top of the regenerator are arranged around the driving rod. Leaf spring fixed connection;

The gap sealing seat is located at the connection between the cold cylinder and the inner cavity of the cold finger, the gap sealing seat and the front end of the regenerator form a room temperature cavity, and the end of the gap sealing seat facing the regenerator is provided with a slope;

There is a through hole on the inner wall of the cooling cylinder above the room temperature cavity, and the connecting pipe is located in the through hole. One end of the connecting pipe is exposed to the outer wall of the cooling cylinder to connect with the compressor, and the other end communicates with the room temperature cavity; the inclined surface at one end of the gap seal seat is in contact with the drive rod located directly below the lower end of the union;

Among them, the edge of the gap sealing seat is closely matched with the inner wall of the cold cylinder, and the edge of the regenerator is slidably matched with the inner wall of the cold finger; the sum of the flexible range of motion of the plate spring along the axis of the cold cylinder is greater than the range of motion of the regenerator;

Preferably, the specification of wire woven square mesh is 200 to 500 per square inch;

Preferably, on the plane where the regenerator and the drive rod are connected, and at the other end of the regenerator, the diameter of the through hole is 0.5-1.5mm,

Preferably, the number of leaf springs is 1 to 3;

Preferably, the material of the plate spring and the wire mesh is stainless steel, and the material of the gap sealing seat, the outer wall of the regenerator, the cold finger, the cold cylinder, the driving rod, the end cover and the connecting pipe is stainless steel or titanium alloy.

It is preferable that the end of the gap sealing seat facing the regenerator is provided with a 30-60° inclined plane with the horizontal plane, that is, a diversion groove;

When assembling, first put the regenerator into the cold finger, and then put the gap sealing seat and the leaf spring into the cold cylinder; the gap between the regenerator and the cold finger, the leaf spring, the gap sealing seat and the driving rod is Micron.

When the free-piston expander is working, the heat load is fixed on the cold finger, and the connecting pipe is connected to the compressor. The compressor generates a pressure wave, which enters the closed space between the gap sealing seat and one end of the regenerator through the connecting pipe, that is, the room temperature cavity ;Because of the diversion groove engraved on the gap seal seat, the airflow transmitted from the compressor can evenly enter the room temperature cavity through the connecting pipe, thus avoiding the impact of the airflow on the drive rod and pushing the regenerator to reciprocate back and forth. The gas sealed between the cold finger and the regenerator expands and cools down to achieve refrigeration.

Among them, the precise positioning support of the regenerator is realized by the plate spring and the gap sealing seat, and the sealing of the working medium gas is realized by the tiny gap between the regenerator and the cold cylinder, and the precise cooperation between the gap sealing seat and the cold cylinder. Heater movement and phase adjustment are driven by compressor pressure waves.

Beneficial effect

Compared with the prior art, the present invention has the advantages that the position eccentricity of the regenerator is reduced when the regenerator is running in the expander through the characteristics of small axial stiffness and large radial stiffness of the leaf spring and the precise cooperation between parts , which reduces the wear and tear during operation, so as to ensure the long life of the refrigerator expander; the pressure wave of the compressor is evenly transmitted to the room temperature chamber of the expander through the slope structure of the gap seal seat, thereby effectively reducing the impact of the pressure wave on the refrigerator when it is working. The impact of the regenerator reduces the vibration of the refrigerator when it is working. There is no driving motor in the cold cylinder, which reduces energy consumption.

Description of drawings

Fig. 1 is a structural schematic diagram of a Stirling refrigerator;

Fig. 2 is the schematic diagram of the axial section of the free piston expander of the present invention;

Among them, 1-plate spring, 2-gap seal seat, 3-regenerator, 4-cooling finger, 5-cooling cylinder, 6-driving rod, 7-end cover, 8-joint pipe.

Detailed ways

Example

A free piston expander as shown in Figure 2, said expander includes: plate spring 1, gap seal seat 2, regenerator 3, cold finger 4, cold cylinder 5, drive rod 6, end cover 7, coupling Tube 8 and peripheral compressor;

Wherein the cold cylinder 5 and the cold finger 4 are both cylindrical cavity structures, the diameter of the cold finger 4 is 1/5 to 1/3 of the cold cylinder 5, the cold cylinder 5 and the cold finger 4 are integrally structured, one end of the cold cylinder 5 and One end of the cold finger 4 is fixedly connected and the inner cavity is connected, and the other end of the cold cylinder 5 is welded with an end cover 7. The cold cylinder 5 and the end cover form a back pressure chamber, and one or more are placed in the back pressure chamber along the longitudinal axis of the cold cylinder 5 The leaf spring 1 has a hole in the center of the leaf spring 1, and the two ends are fixed on the cold cylinder 5;

The regenerator 3 is located in the cold finger 4, and the other end of the cold finger 4 and the rear end of the regenerator 3 form a cold cavity; Or more than one through hole, the through hole communicates with the metal wire braided square hole net, and one or more through holes are opened at the rear end of the regenerator 3, and the through hole makes the metal wire braided square hole net communicate with the cold chamber;

The front end of the regenerator 3 is provided with a drive rod 6, and the through holes at the top of the regenerator 3 are arranged around the drive rod 6. The drive rod 6 extends into the back pressure chamber, passes through the center of the plate spring 1 and is fixedly connected with the center of the plate spring 1 , the top of the driving rod 6 is fixedly connected with the last leaf spring;

The gap sealing seat 2 is located at the connection between the cold cylinder 5 and the inner cavity of the cold finger 4, the gap sealing seat 2 and the front end of the regenerator 3 form a room temperature cavity, and the end of the gap sealing seat 2 facing the regenerator 3 is provided with a slope;

There is a through hole on the inner wall of the cold cylinder 5 above the room temperature chamber, and the joint pipe 8 is located in the through hole. One end of the joint pipe 8 is exposed from the outer wall of the cold cylinder 5 to connect with the compressor, and the other end communicates with the room temperature chamber; the inclined surface at one end of the gap seal seat 2 The contact with the driving rod 6 is located directly below the lower end of the joint pipe 8;

Wherein, the edge of the gap sealing seat 2 is closely matched with the inner wall of the cold cylinder 5, and the edge of the regenerator 3 is slidably matched with the inner wall of the cold finger 4; the sum of the flexible range of movement of the plate spring 1 along the axis of the cold cylinder is greater than the range of the regenerator;

Preferably, the specification of wire woven square mesh is 200 to 500 per square inch;

Preferably, on the plane where the regenerator 3 and the drive rod 6 are connected, and at the other end of the regenerator 3, the diameter of the through hole is 0.5-1.5mm.

Preferably, the number of leaf springs 1 is 1 to 3;

Preferably, the leaf spring 1 and the wire mesh are made of stainless steel, and the materials of the gap sealing seat 2, the outer wall of the regenerator 3, the cold finger 4, the cold cylinder 5, the driving rod 6, the end cover 7 and the connecting pipe 8 are stainless steel or titanium alloy.

Preferably, the end of the gap sealing seat 2 facing the regenerator 3 is provided with a slope 30-60° from the horizontal plane, that is, a diversion groove;

When assembling, first put the regenerator into the cold finger, and then put the gap sealing seat and the leaf spring into the cold cylinder; between the regenerator 3 and the cold finger 4, the plate spring 1, the gap sealing seat 2 and the drive rod 6 The gaps between them are on the micron scale.

When the free piston expander is working, the thermal load is fixed on the cold finger 4, and the connecting pipe 8 is connected to the compressor, and the compressor generates periodically changing pressure waves, which enter the gap sealing seat 2 and the room temperature cavity through the connecting pipe 8; Due to the diversion groove engraved on the gap sealing seat 2, the airflow transmitted from the compressor can enter the room temperature cavity evenly through the connecting pipe 8, thereby avoiding the impact of the airflow on the driving rod 6, and pushing the regenerator 3 back and forth periodically reciprocating motion. During the isothermal expansion process of the working medium gas movement in the cavity, a cooling capacity is generated in the cold cavity. When an electric power of 30W is input, a cooling capacity of 1W is generated.

To sum up, the above are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (6)

1. free-piston decompressor,, it is characterized in that: described decompressor comprises: flat spring (1), clearance seal seat (2), regenerator (3), cold finger (4), cooling cylinder (5), drive rod (6), end cap (7), connection pipe (8) and ancillary equipment compressor;

Wherein cooling cylinder (5) and cold finger (4) are the column type cavity body structure, the diameter of cold finger (4) is 1/5～1/3 of cooling cylinder (5), cooling cylinder (5) and cold finger (4) are structure as a whole, cooling cylinder (5) one ends are fixedlyed connected with cold finger (4) one ends and inner chamber communicates, cooling cylinder (5) other end is welded with end cap (7), cooling cylinder (5) and end cap form back pressure cavity, in back pressure cavity, place one or more flat spring (1) along cooling cylinder (5) y direction, flat spring (1) center drilling, two ends are fixed on the cooling cylinder (5);

Regenerator (3) is positioned at cold finger (4), and the other end of cold finger (4) and regenerator (3) rear end form cold chamber; Be filled with metal wire knitted square hole net in the regenerator (3), have one or more through holes at regenerator (3) front end, through hole and metal wire knitted square hole net UNICOM have one or more through holes in regenerator (3) rear end, and through hole makes metal wire knitted square hole net and cold chamber UNICOM;

Regenerator (3) front end is provided with drive rod (6), the through hole of regenerator (3) front end is arranged around drive rod (6) on the plane of regenerator (3) and drive rod (6) junction, drive rod (6) stretches into back pressure cavity, passing flat spring (1) center and be connected with flat spring (1) center, fixedlys connected with last flat spring in drive rod (6) top;

Clearance seal seat (2) is positioned at the connection position of cooling cylinder (5) and cold finger (4) inner chamber, and clearance seal seat (2) and regenerator (3) front end form the room temperature chamber, and clearance seal seat (2) is provided with the inclined-plane towards an end of regenerator (3);

Have through hole on cooling cylinder (5) inwall of top, room temperature chamber, connection pipe (8) is arranged in through hole, and connection pipe (8) one ends expose cooling cylinder (5) outer wall and are connected with compressor, and the other end communicates with the room temperature chamber; The contact position of the inclined-plane of clearance seal seat (2) one ends and drive rod (6) be positioned at connection pipe (8) lower end under;

Wherein, clearance seal seat (2) edge and cooling cylinder (5) inwall closely cooperate, and the edge of regenerator (3) and cold finger (4) inwall are slidingly matched; Flat spring (1) is along the flexible scope of activities sum of the cooling cylinder axis scope of activities greater than regenerator.

2. a kind of free-piston decompressor according to claim 1, it is characterized in that: the specification of metal wire knitted square hole net is 200～500 per square inch.

3. a kind of free-piston decompressor according to claim 1, it is characterized in that: on the plane of regenerator (3) and drive rod (6) junction, and the through-hole aperture that the other end of regenerator (3) is provided with is 0.5～1.5mm.

4. a kind of free-piston decompressor according to claim 1, it is characterized in that: the quantity of flat spring (1) is 1～3.

5. a kind of free-piston decompressor according to claim 1, it is characterized in that: flat spring (1) and metal wire knitted square hole net materials are stainless steel, and the material of clearance seal seat (2), regenerator (3) outer wall, cold finger (4), cooling cylinder (5), drive rod (6), end cap (7) and connection pipe (8) is stainless steel or titanium alloy.

6. a kind of free-piston decompressor according to claim 1 is characterized in that: clearance seal seat (2) is provided with towards an end of regenerator (3) and becomes 30～60 ° inclined-plane with horizontal plane.

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