CN110714891A

CN110714891A - Compression piston unit and compressor

Info

Publication number: CN110714891A
Application number: CN201911076429.8A
Authority: CN
Inventors: 陈曦; 倪贤灿; 张笑宇; 梁天晓; 洪昊
Original assignee: University of Shanghai for Science and Technology
Current assignee: University of Shanghai for Science and Technology
Priority date: 2019-11-06
Filing date: 2019-11-06
Publication date: 2020-01-21

Abstract

According to the compression piston unit and the compressor of the invention, the compression piston unit comprises a compression piston, a gas bearing inner bushing, a porous flow-limiting belt, a compression piston end cover and a suction valve plate, the compression piston is provided with a cylindrical inner cavity, the outer wall of the compression piston is provided with an inwards concave annular groove and a plurality of concave cavities, the concave cavities are internally provided with throttling through holes communicated with the cylindrical inner cavity, the end surface of the opening end of the compression piston is provided with vent holes communicated with the annular groove, the gas bearing inner bushing is in a straight cylinder shape and is arranged in the inner cavity of the compression piston, the cylinder wall of the gas bearing inner bushing is provided with a plurality of through holes, the porous flow-limiting belt is arranged on the outer side of the gas bearing inner bushing and is positioned between the inner wall of the compression piston and the outer wall of the gas bearing inner bushing, the compression piston end cover is arranged in the cylindrical inner cavity, the air used for passing through backs up the air suction valve plate.

Description

Compression piston unit and compressor

Technical Field

The invention belongs to the field of refrigeration, and particularly relates to a compression piston unit and a compressor.

Background

The low-temperature refrigerating machine is mainly applied to cooling infrared detection devices of an infrared detection system, provides suitable low-temperature working environment (40-120K) for various types of infrared detectors, ensures normal functions of the detectors, improves the sensitivity and resolution of the infrared detectors, and can reduce thermal noise from an optical filter, a cold screen and the optical system. But also for cooling other electronic systems such as on-board laser devices, pod optical windows, etc. Although the number of cryogenic refrigerators is large, the application in the military field is mainly two types, namely a Stirling refrigerator and a throttling refrigerator, and as the required refrigerating capacity is gradually increased and the refrigerating time is gradually increased, part of the throttling refrigerator needs to be replaced by the Stirling refrigerator.

The split Stirling refrigerator is a high-precision mechanical and electrical integration product, and the development direction of the split Stirling refrigerator is miniaturization and long service life. The split Stirling refrigerator has a piston and cylinder kinematic pair which relatively move at high frequency and high speed in the split Stirling refrigerator, a gap is sealed between the piston and the cylinder, the sealing gap is small, lubricating oil cannot be used, and high-pressure high-purity easy-leakage refrigerating working medium helium is arranged in the split Stirling refrigerator, so that the service life of the split Stirling refrigerator is a key and difficult technology for development. The service life of the existing light-weight split Stirling refrigerator with small volume and light weight is usually 3000-5000 hours, and the maximum time is not more than 10000 hours; the existing long-life Stirling refrigerating machine generally has the defects of large volume, heavy weight and complex structure, and the weight is generally 5-l 5 kg. The efficient lightweight free piston linear compressor is a main part of a Stirling refrigerator for efficient refrigeration and is also an energy consumption part. The application of the moving-magnet type efficient motor and the gas bearing technology ensures the high efficiency and reliability of the linear compressor, reduces the requirements on the spring, and is beneficial to realizing high efficiency and light weight design at the same time.

The long service life and the miniaturization of the compressor are a pair of contradictions in the research of the Stirling refrigerator, and the long service life is not easy to realize if the compressor is miniaturized; miniaturization is difficult to achieve for long life.

Disclosure of Invention

One of the objects of the present invention is to provide a novel compression piston unit and compressor for a pneumatically split stirling cooler.

The invention provides a compression piston unit which is characterized by comprising a compression piston, a gas bearing inner bushing, a porous flow-limiting belt, a compression piston end cover and a suction valve plate, wherein the compression piston is provided with a cylindrical inner cavity, the outer wall of the compression piston is provided with an inwards concave annular groove and a plurality of concave cavities, the concave cavities are internally provided with throttling through holes communicated with the cylindrical inner cavity, the end surface of the opening end of the compression piston is provided with vent holes communicated with the annular groove, the gas bearing inner bushing is in a straight cylinder shape and is arranged in the inner cavity of the compression piston, the cylinder wall of the gas bearing inner bushing is provided with a plurality of through holes, the porous flow-limiting belt is arranged on the outer side of the gas bearing inner bushing and is positioned between the inner wall of the compression piston and the outer wall of the gas bearing inner bushing, the compression piston end cover is arranged in the cylindrical inner cavity of the compression piston, the, used for ejecting the air suction valve plate through air.

In the compression piston unit provided by the present invention, there may be further provided the features of: wherein, the outer wall of the compression piston is also provided with a Teflon coating.

In addition, in the compression piston unit provided by the present invention, there may be further provided a feature that: wherein, a plurality of cavities are arranged along the circumference and are respectively positioned at two sides of the annular groove.

In addition, in the compression piston unit provided by the present invention, there may be further provided a feature that: wherein, the outer wall of the inner bushing of the gas bearing is provided with an axial gap.

In addition, in the compression piston unit provided by the present invention, there may be further provided a feature that: wherein, the outer surface of the compression piston end cover is provided with a ring groove for placing a sealing ring.

In addition, in the compression piston unit provided by the present invention, there may be further provided a feature that: wherein, the end cover through hole is a waist-shaped step hole.

The present invention provides a compressor having such features, including a linear motor; and two compression piston units, wherein the linear motor has a motor support, and the compression piston unit is the compression piston unit of any one of claims 1 to 6.

The compressor provided by the present invention may further have the following features: the motor support comprises a flange and a compression piston pipe, the compression piston pipe is provided with a cylindrical inner cavity, the axis of the compression piston pipe is collinear with the axis of the flange, concave air inlet grooves are symmetrically formed in the outer wall of the compression piston pipe, and through holes communicated with the air inlet grooves and the inner cavity of the compression piston pipe are formed in the air inlet grooves.

In addition, the compressor provided by the present invention may further have the following features: wherein, two compression pistons are symmetry respectively and are set up in the cylindrical inner chamber of compression piston pipe, and the open end of two compression pistons sets up relatively.

Disclosure of the invention and effects

The compression piston unit and the compressor comprise a compression piston assembly, a motor bracket and a compressor outer shell. The design structure of the high-efficiency light-weight linear compressor, in particular to the application of the moving magnet type high-efficiency motor structure and the gas bearing technology, ensures the high efficiency and the reliability of the linear compressor, reduces the requirement on a spring, and is beneficial to realizing the high efficiency and light-weight design at the same time.

Drawings

FIG. 1 is a schematic view of a compressor according to a first embodiment of the present invention;

FIG. 2 is an exploded view of a compression assembly in an embodiment of the present invention;

FIG. 3 is a schematic view of the assembly of the compression piston with the motor mount in an embodiment of the invention;

FIG. 4 is a schematic diagram of an external shape of a motor bracket according to a first embodiment of the present invention;

FIG. 5 is a schematic view of a compression piston configuration in an embodiment of the present invention;

FIG. 6 is a view in the direction A of FIG. 5;

FIG. 7 is a sectional view taken in the direction of FIG. 6B-B;

FIG. 8 is a view of a compression piston according to a third embodiment of the present invention;

FIG. 9 is a sectional view in the direction of FIG. 8C;

FIG. 10 is a cross-sectional view taken in the direction of E-E of FIG. 9;

FIG. 11 is a schematic perspective view of an inner liner for a gas bearing in an embodiment of the present invention;

FIG. 12 is a perspective view of a compression piston end cap in an example of the invention;

FIG. 13 is a view in the direction D of FIG. 12;

FIG. 14 is a sectional view in the direction F-F in FIG. 13;

FIG. 15 is a schematic view of an intake valve plate according to an embodiment of the present invention;

FIG. 16 is a schematic view of a gas bearing inner liner in accordance with an embodiment of the present invention.

Detailed Description

In order to make the technical means, the creation features, the achievement purposes and the effects of the invention easy to understand, the compression piston unit and the pneumatic split-type stirling cryocooler of the invention are explained in the following embodiments with reference to the attached drawings.

Example one

As shown in fig. 1, the compressor of the pneumatically-split stirling includes a linear motor, two compression piston units, and a compressor outer housing 34.

The linear motor comprises an inner yoke 3, an outer yoke 4, a permanent magnet 5, a permanent magnet support 6, a coil 7, a coil support 8, an outer yoke pressing plate 9 and a motor support 29.

As shown in fig. 4, the motor bracket 29 includes a flange 291 and a compression piston tube 32.

The flange 291 is disk-shaped, steps 33 for fixing the permanent magnet 5 are provided on both sides of the flange 291, and an air inlet hole 292 for communicating the outside with the compression piston tube 32 is provided on the circumferential surface of the flange 291 as shown in the figure.

The compression piston pipe 32 is a straight-through pipe and is provided with a cylindrical inner cavity, the straight-through pipe is arranged in the center of the flange 291, two ends of the compression piston pipe 32 are free ends and are symmetrically distributed on two sides of the flange, the axis of the compression piston pipe 32 is collinear with the axis of the flange 291, two concave air inlet grooves 31 are symmetrically arranged on the outer wall of the compression piston pipe 32, the sections of the air inlet grooves 31 are rectangular, the air inlet grooves 31 are axially arranged from the end parts of the free ends to the other end of the compression piston pipe 32, through holes 30 are formed in the grooves, and the through holes 30 are communicated with the air inlet grooves 31 and the cylindrical.

The purpose of the through-holes 30 is to guide the back pressure chamber gas to the compression chamber through the compression piston, preventing the piston stroke from dropping due to the rise of the back pressure chamber pressure caused by the gas bearing.

As shown in fig. 1, the linear motor includes an outer yoke 4, an inner yoke 3, and a mover, the outer yoke 4 and the inner yoke 3 are respectively disposed on a frame 29 with a gap between the outer yoke 4 and the inner yoke 3, the mover is disposed in the gap, and the mover includes a permanent magnet 5 and a permanent magnet support 6.

The outer yoke iron 4, the coil 7, the permanent magnet 5 and the inner yoke iron 3 are all annular and are coaxially arranged. The outer yoke 4 and the inner yoke 3 are respectively arranged on the bracket 29, a gap is arranged between the outer yoke 4 and the inner yoke 3, and the mover is arranged in the gap.

The permanent magnet 5 is connected with the permanent magnet support 6, the outer yoke iron 4 and the inner yoke iron 3 are made of soft magnetic materials, common electrician pure iron, silicon steel sheets and other materials, and the permanent magnet 5 is made of permanent magnetic materials, common neodymium iron boron and aluminum nickel cobalt permanent magnetic materials.

When the coil is energized with direct current, the outer yoke 4 and the inner yoke 3 form a magnetic loop, thereby generating magnetic poles on the outer yoke 4 and the inner yoke 3. When alternating current is supplied to the coil, the permanent magnet 5 is reciprocated by the alternating electromagnetic force. When the permanent magnet 5 reciprocates, the rotor is driven to reciprocate linearly.

As shown in fig. 2, the compression piston unit comprises a compression piston 10, a compression piston end cover 14, a gas bearing inner bushing 12, a suction valve plate 13, a porous flow-limiting belt 11 and a thrust washer 15.

As shown in fig. 5, the compression piston 10 has a cylindrical blind hole with an open end, a plurality of annular cavities are circumferentially formed on an outer wall of the compression piston, throttle through holes 18 are formed in the annular cavities, annular grooves 20 are formed on an outer wall of the compression piston 10, and the annular cavities are respectively disposed at both sides of the annular grooves 20.

As shown in fig. 6, two vent holes 21 are arranged on the end surface of the opening end of the compression piston 10, an air inlet hole 19 is arranged in the annular groove 20, the vent holes 21 are communicated with the air inlet hole 19, air passes through the annular groove 20 on the compression piston 10 from the air inlet hole 30 on the motor support 29, then enters the air inlet hole 19 on the compression piston, and enters the compression cavity through the piston inner hole 21, so that the pressure inside and outside the cylinder is kept consistent.

As shown in fig. 7, the compression piston 10 has 8-10 orifices 18 on its surface, 4-5 orifices are evenly distributed on both ends, and the piston is supported by gas to be used as a gas bearing.

As shown in fig. 1, two compression pistons 10 are symmetrically disposed in the cylindrical inner cavities of the compression piston tubes 32, respectively, and open ends of the two compression pistons 10 are disposed opposite to each other.

The compression piston 10 is connected to the permanent magnet holder 6, in the embodiment by means of screws. When the permanent magnet 5 reciprocates, the compression piston 10 is driven to reciprocate linearly.

If the annular groove 20 is not formed on the surface of the compression piston 10, when the compression piston 10 is rotationally offset from the compression piston tube 32, the air inlet hole 19 of the compression piston 10 in the equilibrium position is not vertically aligned with the air inlet hole 30 of the motor bracket 29, and the air in the back pressure chamber cannot enter the compression chamber, which results in inconsistent air pressure inside and outside the compression piston tube 32.

The porous restrictor band 11 and the gas bearing inner liner 12 are both disposed within the cylindrical cavity of the compression piston 10, and the porous restrictor band 11 is disposed outside the gas bearing inner liner 12.

In order to enable the porous flow-limiting belt 11 to be better attached to the inner wall surface of the compression piston 10 to achieve interference fit, a straight-tube-shaped gas bearing inner bushing 12 is designed. As shown in fig. 11, the gas bearing inner liner 12 is provided with 5 square groove through holes 26 along the circumference to allow the gas inside the compression piston 10 to pass through the porous restrictor band 11 and enter the orifice 18. Meanwhile, a clamp spring groove 27 is formed in the inner liner 12 of the gas bearing, and the inner liner 12 of the gas bearing is opened by using the tension of a clamp spring, so that the porous flow-limiting belt 11 is more attached to the inner wall surface of the compression piston 10. Meanwhile, a notch 28 with the thickness of 0.6-0.8mm is formed in the outer wall of the inner bushing 12 of the gas bearing along the axial direction, so that the inner bushing 12 of the gas bearing is easier to open.

As shown in fig. 7, the compression piston 10 has a step 17 formed therein for placing a compression piston end cap, and a circlip groove 16 formed on the other side thereof for limiting the axial movement of the compression piston end cap.

As shown in fig. 1 and 2, the thrust washer 15, the compression piston end cover 14 and the suction valve plate 13 are respectively arranged in a cylindrical cavity of the compression piston 10, and are sequentially arranged from an opening of the cylindrical cavity, and the thrust washer 15 is arranged in the clamp spring groove 16.

As shown in fig. 12, 13 and 14, two stepped holes with different sizes, namely, a hole 23 and a hole 22, are formed in the compression piston end cover 14, and the cross sections of the holes are waist-shaped, so that the gas in the compression cavity can better push open the suction valve plate 13 on the compression piston end cover 14.

The holes 23 can increase the impact force of the air flow, so that the suction valve plate 13 can be opened more easily, and the holes 22 can reduce the dead volume of the piston and increase the refrigeration efficiency of the refrigerator.

The surface of the end cover of the compression piston is provided with an annular groove 25 for placing a sealing ring.

As shown in fig. 15, two butterfly-shaped holes 36 and a central hole 37 are formed in the suction valve plate 13, and the two butterfly-shaped holes 36 can reduce the weight of the whole machine in a first action and can enable the suction valve plate 13 to be opened more easily in a second action. The threaded hole 24 is located at the position of the central hole 37 of the suction valve plate 13 and is used for fixing the compression piston end cover 14 together.

As shown in fig. 3, when the compression piston unit is in the equilibrium position, the air inlet hole 30 of the motor bracket 29 is aligned with the annular groove 20 of the compression piston 10, and the air in the back pressure chamber enters the compression chamber through the hole 21 of the compression piston, so that the pressure inside and outside the cylinder 32 is kept uniform. When the compression piston 10 deviates from the axial equilibrium position and moves towards both sides, the annular groove 20 on the compression piston and the air inlet hole 30 on the motor bracket are staggered, so that the air in the back pressure cavity can not enter the compression cavity. Meanwhile, gas in the compression cavity passes through a stepped waist-shaped hole of a compression piston end cover 14, pushes open a suction valve plate 13, enters the compression piston, passes through a gas bearing inner bushing 12 and a porous flow limiting belt 11, and is sprayed out of a throttling hole 18, so that the compression piston is supported.

The compressor outer housing 34 is disposed outside the motor bracket 29, and the linear motor and the compression piston unit are disposed inside the compressor outer housing 34.

Example two

The other structures of the embodiment are the same as those of the first embodiment, in order to reduce the friction of the compression piston in the reciprocating process, a Teflon coating layer 9 with the thickness of 0.1-0.3mm is plated on the surface of the compression piston, and Teflon coating layer materials are also called polytetrafluoroethylene, so that the Teflon coating layer materials have the characteristic of high temperature resistance, are extremely low in friction coefficient and are very suitable for being used as a lubricant, and the service life of the Stirling refrigerator is greatly prolonged.

EXAMPLE III

The other structure of the present embodiment is the same as that of the first embodiment except that the structure of the gas bearing inner liner is different from that of the gas bearing inner liner 12 of the first embodiment.

As shown in fig. 16, this embodiment provides a simple gapless gas bearing liner 38, instead of the gas bearing liner 12 of the second embodiment, which is characterized by simple structure and easy use, and the material expands under heat, so that the porous restrictor band can tightly abut against the inner wall of the compression piston 10, and the air flow enters the interior of the piston through the square hole 39.

Example four

The other structure of the present embodiment is the same as that of the embodiment except that the compression piston is different in structure from the compression piston 10 of the embodiment one.

As shown in fig. 8, 9 and 10, the present embodiment provides a compression piston 41 instead of the compression piston 10 of the second embodiment.

The compression piston 41 is characterized by a simple structure and a slightly lower processing difficulty than the former. The annular groove 40 is deepened such that the hole 21 is in direct communication with the annular groove 40, as in the compression piston 41 of fig. 10, so that gas in the annular groove 40 can directly enter the hole 21.

Effects and effects of the embodiments

Compared with the conventional compression unit, the compression piston assembly of the embodiment adopts a gas bearing technology, greatly reduces the friction in the piston operation process, prolongs the service life of the Stirling refrigerator, and simultaneously ensures that the Stirling refrigeration structure is simpler and the weight is lighter.

In addition, the ring-shaped groove is formed in the surface of the compression piston, so that the phenomenon of unstable air pressure caused when the compression piston and the air cylinder are subjected to rotary offset can be avoided, stable ventilation is still kept, and the efficient operation of the Stirling refrigerator is facilitated.

Furthermore, for the design of the compression live competition end cover, the stepped waist-shaped hole is adopted, so that the dead volume in the operation process is reduced, the Stirling refrigeration efficiency can be improved, and the opening of the air suction valve plate is facilitated.

Furthermore, the gas bearing inner bushing is provided with a clamp spring groove for placing a clamp spring, the inner bushing is opened by using the tension of the clamp spring, the air flow limiting belt can better cling to the inner wall surface of the compression piston, and air flow can uniformly pass through holes of the air flow limiting belt.

Furthermore, the surface of the compression piston is coated with a lubricating Teflon coating material, so that the loss of the piston in motion can be greatly reduced, and the service life of the Stirling refrigerator is greatly prolonged.

The embodiment is optimized in the structure of the compression unit, so that the compressor is compact and light, the designed compression piston assembly can enable the compressor to run more efficiently, and meanwhile, the service life of the split Stirling refrigerator is greatly prolonged.

The above embodiments are preferred examples of the present invention, and are not intended to limit the scope of the present invention.

Claims

1. A compression piston unit, comprising:

a compression piston, a gas bearing inner bushing, a porous flow-limiting belt, a compression piston end cover and an air suction valve plate,

the compression piston is provided with a cylindrical inner cavity, the outer wall of the compression piston is provided with an inwards concave annular groove and a plurality of concave cavities, the concave cavities are internally provided with throttling through holes communicated with the cylindrical inner cavity, the end surface of the opening end of the compression piston is provided with vent holes communicated with the annular groove,

the gas bearing inner bushing is in a straight cylinder shape and is arranged in the inner cavity of the compression piston, a plurality of through holes are arranged on the wall of the gas bearing inner bushing,

the porous flow-limiting belt is arranged on the outer side of the gas bearing inner bushing and is positioned between the inner wall of the compression piston and the outer wall of the gas bearing inner bushing,

the compression piston end cover is arranged in the cylindrical inner cavity of the compression piston, the air suction valve plate is arranged on the compression piston end cover,

and an end cover through hole is formed in the end cover of the compression piston and used for jacking the air suction valve plate through air.

2. The compression piston unit of claim 1, wherein:

wherein, the outer wall of the compression piston is also provided with a Teflon coating.

3. The compression piston unit of claim 1, wherein:

the concave cavities are arranged along the circumference and are respectively positioned on two sides of the annular groove.

4. The compression piston unit of claim 1, wherein:

wherein, the outer wall of the inner bushing of the gas bearing is provided with an axial gap.

5. The compression piston unit of claim 1, wherein:

and the outer surface of the compression piston end cover is provided with an annular groove for placing a sealing ring.

6. The compression piston unit of claim 1, wherein:

the end cover through hole is a waist-shaped step hole.

7. A compressor, comprising:

a linear motor; and

two compression piston units are arranged on the piston rod,

wherein the linear motor is provided with a motor bracket,

the compression piston unit is as claimed in any one of claims 1 to 6.

8. The compressor of claim 7, wherein:

wherein the motor bracket comprises a flange and two compression piston pipes,

the compression piston tube having a cylindrical lumen, the axis of the compression piston tube being collinear with the axis of the flange,

the compression piston pipe is characterized in that concave air inlet grooves are symmetrically formed in the outer wall of the compression piston pipe, and through holes communicated with the air inlet grooves and the inner cavity of the compression piston pipe are formed in the air inlet grooves.

9. The compressor of claim 8, wherein:

the two compression pistons are respectively and symmetrically arranged in the cylindrical inner cavities of the two compression piston pipes, and the open ends of the two compression pistons are oppositely arranged.