JPH10227284A - Linear compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear compressor which can prevent the wear of a piston part by restricting the shaft swing of a piston and enable the long life of a device. SOLUTION: A coil movable linear compressor having compression chambers 2, 3 in both sides of a housing 1 is provided with a plate-shaped piston spring 20, provided between the housing 1 and piston shaft 12, for elastically supporting first/second pistons 7, 10 so as to be able to reciprocate in first/second cylinders 6, 9 respectively and gas bearings 41, 42 for regulating the position of the axial direction of the first/second pistons 7, 10 by spouting one part of a compressed gas from the compression chamber 2, 3 in the first/second cylinders 6, 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear compressor for compressing gas and supplying the compressed gas to the outside by reciprocating a piston fitted in a cylinder by a linear motor.

[0002]

2. Description of the Related Art In recent years, a linear compressor has been developed as a mechanism for compressing and supplying a refrigerant gas in a refrigeration system. For example, as shown in FIG. 4, a housing 101 having a bottomed cylindrical body, a magnetic frame 102 made of low carbon steel formed at an upper end opening of the housing 101, and a cylinder 103 formed at the center of the magnetic frame 102 When,
Reciprocally fitted in the cylinder 103, the cylinder 10
Piston 105 for forming compression chamber 104 in inner space 3
And a linear motor 106 as a drive source for driving the piston 105 back and forth.

In the linear motor 106, an annular permanent magnet 107 is arranged concentrically outside the cylinder 103 and is fixed to the housing 101. This magnet 10
A magnetic field B is generated in a cylindrical gap 108 concentric with the center of the cylinder 103 by a magnetic circuit including the magnetic frame 7 and the magnetic frame 102. The gap 105 has a piston 105 at the center.
Cylindrical movable body 10 made of resin integrally fixed to
A coil spring 110 for elastically supporting the movable body 109 and the piston 105 so as to reciprocate is fixed to the housing 101.

A magnet 107 is mounted on the outer periphery of the movable body 109.
The electromagnetic coil 111 is wound at a position facing the
By passing an alternating current of a predetermined frequency through a lead wire (not shown), the coil 111 and the movable body 109 are driven by the action of a magnetic field passing through the gap 108, and the piston 10
5 is reciprocated in the cylinder 103 to generate a gas pressure in a predetermined cycle in the compression chamber 104.

On the other hand, as a typical refrigeration system, FIG.
As shown in FIG. 1, a hermetic refrigeration system in which a linear compressor 121 (compressor), a condenser 122, an expansion valve 123, and an evaporator 124 are connected by a gas flow path pipe 125 is known. The refrigerant gas vaporized by the condenser 124 is sucked through a gas flow pipe 125 and compressed to a high pressure, and the high pressure refrigerant gas is discharged to the condenser 122 through the gas flow pipe 125.

For this reason, as shown in FIG.
4 includes a valve mechanism 1 provided at the upper end of the cylinder 103.
12, a gas flow path pipe 12 outside the housing 101.
5 is connected. The valve mechanism 112 is connected to the gas flow pipe 1
The suction valve 112a allows only the suction of the refrigerant gas from the evaporator 124 through the inlet 25, and the discharge valve 112b allows only the discharge of the refrigerant gas to the condenser 122 through the gas flow pipe 125. You. The suction valve 112 a is a valve that causes a gas to flow in the direction of the compression chamber 104 by a pressure difference between the refrigerant gas in the gas passage pipe 125 on the low pressure side and the compression chamber 104. Further, the discharge valve 112b is opened by the pressure difference of the refrigerant gas between the compression chamber 104 and the gas passage pipe 125 on the high pressure side so that the discharge valve 112b opens when the refrigerant gas pressure in the compression chamber 104 becomes equal to or higher than a predetermined pressure. This is a valve that allows gas to flow out in the direction of the gas flow pipe 125. The suction valve 112a and the discharge valve 112b are both valves that are biased by leaf springs.

With the above arrangement, in the conventional apparatus, the suction valve 1
After the refrigerant gas sucked from 12a is compressed to a high pressure in the compression chamber 104, it is supplied to the condenser 122 via the discharge valve 112b.

Recently, as disclosed in Japanese Patent Application Laid-Open No. 2-154950, a single linear motor is used.
It has been proposed to provide a compression chamber on both sides in a housing and operate two pistons alternately to improve efficiency.

[0009]

However, the one disclosed in Japanese Unexamined Patent Publication No. 2-154950 or the like is the one disclosed in FIG.
Not a movable coil as shown in the figure above, but a linear motor drive system of a movable magnet type is adopted, so a force due to a magnetic field is applied to the piston in a direction perpendicular to the moving direction of the piston, so the piston part is likely to be worn and prolonged use Had the disadvantage of being unsuitable.

For this reason, in a linear compressor that has been used for a long period of time, it is conceivable to change the drive system of the linear motor to a coil movable type in which the force of the magnetic field of the linear motor acts only in the same direction as the piston moves. However, in this case, it is difficult to control the center position of the stroke of the piston to be constant, and therefore, there has been a problem that highly efficient operation cannot be performed.

Conventionally, in the refrigerating system, a coil spring is often used as a member for elastically supporting the housing in order to allow the piston to reciprocate in the cylinder. A plate-shaped piston spring that is superior to the conventional coil spring in terms of position control and the like has been proposed, and various improvements have been studied (Tomiyoshi Haruyama et al., 48th, 1st.
Proceedings of the 1999 Low Temperature Engineering and Superconductivity Society of Japan B2-
4, P166).

This plate-shaped piston spring is generally called a suspension spring, and its shape is, as shown in FIG. 6, formed in a disk-shaped plate spring 20a by a plurality of spiral notches toward the center. The configuration is such that the portions 20b are evenly provided.

By using the plate-shaped suspension spring 20 as the above-described piston spring, it is possible to make the stroke center position of the piston constant with a simple configuration.

However, in the case of the plate-shaped suspension spring 20, it is impossible to limit the axial deflection of the piston in the vicinity of the vertical dead center of the piston where the spring is fully extended. There is a possibility that the piston portion may be worn out by one side.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is directed to a linear compressor having compression chambers on both sides in a housing and compressing gas by driving a coil movable linear motor to supply the gas to the outside. A linear compressor with a simple configuration that keeps the center of the stroke of the piston constant, limits shaft deflection of the piston during reciprocating drive of the piston, prevents wear on the piston, and extends the life of the device. The purpose is to provide.

[0016]

SUMMARY OF THE INVENTION According to the present invention, there are provided first and second cylinders provided on both sides of a housing, reciprocally fitted in the first and second cylinders, and compressed in each cylinder. First and second pistons that respectively define chambers, piston shafts whose both ends are fixed to the first and second pistons, and a bottomed cylindrical movable body integrally fixed to the piston shafts, A linear motor that is disposed in a gap formed in a part of a magnetic circuit composed of a magnet and a magnetic frame, and that reciprocates a piston by supplying an alternating current of a predetermined frequency to an electromagnetic coil wound around the outer periphery of the movable body; A first and a second member provided between the housing and the piston shaft;
A plate-like piston spring for elastically supporting a piston so as to reciprocate in the first and second cylinders; And a gas bearing part for regulating the axial position of the piston.

By using this configuration, when the first and second pistons are located near the neutral point, the position of the first and second pistons in the axial direction is regulated by the plate-like piston springs. When the first and second pistons are located in the vicinity of the vertical dead center, the axial position of the first and second pistons is regulated by the gas bearing. Therefore, the stroke center positions of the first and second pistons are made constant with a simple configuration, and the axial movement of the pistons during the reciprocating drive of the first and second pistons is restricted to prevent wear of the piston portions, The life of the device can be extended.

As a specific configuration, a first communication passage for supplying a compressed gas from a compression chamber in a first cylinder to a gas bearing portion, and a compressed gas from a compression chamber in a second cylinder to a gas bearing portion. And a second communication path for supplying the air to the second communication path.

By using this configuration, a part of the compressed gas from the compression chamber is used to supply the gas to the gas bearing portion. Therefore, it is not necessary to newly provide a means for supplying the gas, and the apparatus is not required. Can be reduced in size.

[0020] More preferably, the first communication passage is formed in the first piston and the piston shaft, and the second communication passage is formed in the second piston and the piston shaft.
By using this configuration, gas is blown from the piston shaft side to the bearing side, so that the structure of the entire apparatus can be simplified as compared to the opposite case.

Further, a gas bearing portion is provided in the first cylinder on the back side of the first piston to regulate the axial position of the first piston, and a gas bearing portion on the back side of the second piston. The second piston may be provided in the second cylinder, and may control the axial position of the second piston.

By using this configuration, shaft deflection when the first piston is located in the vicinity of the vertical dead center is limited by the first gas bearing portion, and the first piston is vertically shifted by the second gas bearing portion. Shaking of the shaft when it is located in the vicinity is limited.

Further, the first and second pistons have a minute gap, specifically, 10 μm, in the first and second cylinders, respectively.
A configuration may be adopted in which the reciprocation is freely inserted through a minute gap set to be equal to or less than m.

By using this configuration, a gas seal is formed between the piston and the cylinder as the piston reciprocates,
There is no need to separately provide a gas seal member on the peripheral surface of the piston. Therefore, it is possible to realize a clearance seal having no contact between the piston and the cylinder, and it is possible to prevent a decrease in operating efficiency due to a friction loss between the piston and the cylinder when the piston reciprocates.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the linear compressor according to the present invention will be described below with reference to the drawings.
Note that the same components as those of the above-described conventional device are denoted by the same reference numerals, and detailed description of these portions will be omitted.

As shown in FIG. 5, the linear compressor of the present invention is used as a compressor of a closed type refrigeration system. As a linear compressor, as shown in FIG.
And holds the linear compressor as an enclosed space. The housing 1 has compression chambers 2 and 3 at its upper and lower parts.

A magnetic frame (yoke) 4 made of low carbon steel is formed on the upper part of the housing 1.
A cylinder fitting hole 5 extending in the vertical direction is formed through a central portion of the cylinder, and a bottomed cylindrical first cylinder 6 made of stainless steel is fitted into the cylinder fitting hole 5.

In the first cylinder 6, a first piston 7 is reciprocally inserted through a small gap so as to reciprocate, and the upper compression chamber, which serves as a compression space for refrigerant gas, by the first cylinder 6 and the first piston 7. 2 are defined. The first cylinder 6 is provided with a first suction valve 8a connected to an external gas flow path pipe 125 for sucking the refrigerant gas vaporized by the evaporator 124.

On the other hand, a second cylinder 9 extending vertically is provided below the housing 1 on the side opposite to the first cylinder 6, and a second piston 10 has a small gap in the second cylinder 9. The lower compression chamber 3 is formed by the second cylinder 9 and the second piston 10 as a compression space for the refrigerant gas. Similarly to the upper compression chamber 2, the second cylinder 9 is provided with a second suction valve 11a connected to an external gas flow path pipe 125 for sucking the refrigerant gas vaporized by the evaporator 124. .

The first piston 7 and the second piston 10 are connected by a piston shaft 12,
A cylindrical movable body (bobbin) 13 with a bottom and an open side of the piston 7 is integrally fixed to the piston shaft 12.

An annular recess 15 is formed in the yoke 4 so as to be concentric with the cylinder fitting hole 5. An annular permanent magnet 16 is provided on the outer side surface 15a of the recess 15 between the yoke 4 and the inner side surface 15b. The magnet 16 and the yoke 4 form a magnetic circuit 18 of a linear motor 17. The magnetic circuit 18 allows the magnetic circuit 18 to attach the magnetic circuit 18 to the gap S between the magnet 16 and the inner side surface of the recess 15. A magnetic field having a predetermined strength is generated. The bobbin 13 is disposed in a gap S formed in a part of a magnetic circuit 18 including the magnet 16 and the yoke 4, and supplies an alternating current of a predetermined frequency to an electromagnetic coil 19 wound around the bobbin 13. The first piston 7 and the second piston 1
0 is reciprocated in the first cylinder 6 and the second cylinder 9, respectively, so as to generate a gas pressure of a predetermined cycle in the upper compression chamber 2 and the lower compression chamber 3.

The piston shaft 12 is provided with a plate-shaped suspension spring 20 for elastically supporting the first piston 7 and the second piston 10 in a reciprocating manner. And the suspension spring 20
The central portion is integrally fixed to the central position of the piston shaft 12, and the outer peripheral portion is fixed to the housing 1 to elastically support the first piston 7 and the second piston 10 so as to be able to reciprocate. The suspension spring 20 is made of spring steel, and its specific shape is the same as that described in the section of [Prior Art], so that the detailed description is omitted here.

As described above, in the linear compressor having the compression chambers 2 and 3 on both sides, by disposing the suspension spring 20 at the center position of the piston shaft 12, the stroke center position of the first and second pistons 7 and 10 is adjusted. Can be easily controlled.

Further, a compressed gas from the upper compression chamber 2 in the first cylinder 6 is supplied to the first piston 7 and the piston shaft 12 to a first gas bearing 41 and a second gas bearing 42 which will be described later. A first communication passage 51 is provided in the second piston 10 and the piston shaft 12 for supplying compressed gas from the lower compression chamber 3 in the second cylinder 9 to the first gas bearing portion 41 and the second A second communication passage 52 for supplying the gas to the gas bearing portion 42 is provided.

In the first gas bearing portion 41 and the second gas bearing portion 42, during the compression stroke in which the first piston 7 is located near the top dead center, the upper compression chamber 2 in the first cylinder 6 is formed.
A part of the compressed gas from the piston is ejected from the piston shaft 12 to the bearing side through the first communication passage 51. On the other hand, in the compression stroke in which the second piston 10 is located near the top dead center,
A part of the compressed gas from the lower compression chamber 3 in the second cylinder 9 is ejected from the piston shaft 12 to the bearing via the second communication passage 52.

As a result, the suspension spring 20 is fully extended in the vicinity of the top and bottom dead centers of the first piston 7 and the second piston 10, so that the suspension spring 20 cannot sufficiently restrict the axial movement of the piston. Instead, the first gas bearing part 41 and the second
The gas bearing 42 makes it possible to reliably prevent the first piston 7 and the second piston 10 from running out of shaft.

With the above configuration, the pressure difference between the upper compression chamber 2 and the gas bearings 41 and 42 increases during the period when the first piston 7 is located near the top dead center, and the compression from the upper compression chamber 2 Part of the gas is supplied to the first gas bearing 41 and the second gas bearing 42 via the first communication passage 51,
Compressed gas is blown from the piston shaft 12 to the bearing side.

During the period in which the second piston 10 is located near the top dead center, the lower compression chamber 3 and the gas bearing 41,
42, a part of the compressed gas from the lower compression chamber 3 is supplied to the first gas bearing portion 41 and the second gas bearing portion 42 through the second communication passage 52, and the piston shaft 12 Compressed gas is blown to the bearing side from.

FIGS. 2 and 3 are cross-sectional views showing states when gas is discharged from the upper compression chamber 2 and the lower compression chamber 3, respectively. Here, the arrows in the figure indicate the displacement direction of the pistons 7 and 10, and the flow of the compressed gas in the upper compression chamber 2 and the lower compression chamber 3 accompanying the movement of the pistons 7 and 10.

As is clear from the figure, the first piston 7
Of the compressed gas in the upper compression chamber 2 through the first communication passage 51,
It is supplied to the first and second gas bearing portions 42 (see FIG. 2), and conversely, with the movement of the second piston 10 near the top dead center,
Part of the compressed gas in the lower compression chamber 3 is supplied to the first gas bearing 41 and the second gas bearing 42 via the second communication passage 52 (see FIG. 3).

The first piston 7 and the second piston 1
When 0 is located near the neutral point, the compression chambers 2, 3
The pressure difference between the gas bearings 41 and 42 becomes smaller,
The compressed gas is not blown from the piston shaft 12 to the bearing side, and a sufficient effect cannot be expected as the gas bearing portions 41 and 42. In this case, the suspension spring 12 causes the shafts of the first piston 7 and the second piston 10 to rotate. The position in the direction is regulated. Therefore, a reduction in the efficiency of the apparatus due to the supply of the compressed gas from the compression chambers 2 and 3 can be suppressed as much as possible.

Accordingly, when the first piston 7 and the second piston 10 are located near the neutral point, the suspension spring 12 regulates the position of the first piston 7 and the second piston 10 in the axial direction. When the first piston 7 and the second piston 10 are located in the vicinity of the vertical dead center, the first gas bearing 41 and the second gas bearing 42 allow the first piston 7 and the second piston 10 to move in the axial direction. Position regulation is performed, the stroke center positions of the pistons 7 and 10 are kept constant with a simple configuration, and the axial movement of the pistons 7 and 10 at the time of reciprocating driving of the pistons 7 and 10 is restricted to prevent the piston portions from moving. Wear can be prevented and the life of the device can be extended.

The description of the above embodiment is for the purpose of explaining the present invention, and should not be construed as limiting the invention described in the claims or reducing the scope thereof. Also, the configuration of each part of the present invention is not limited to the above-described embodiment,
It goes without saying that various modifications are possible within the technical scope described in the claims.

For example, the first communication passage 51 and the second communication passage 5
2 is provided in the first piston 7, the second piston 10 and the piston shaft 12, but in addition to these, the communication passages 51 and 52 are formed by the first cylinder 6, the second cylinder
Cylinders 6 and 9 are provided in cylinder 9 and housing 1.
The compressed gas may be ejected from the side to the piston shaft 12 side.

[0045]

As described above, according to the present invention, the center position of the stroke of the piston can be controlled with a simple structure, and the efficiency of the linear compressor can be increased.

Further, with a simple configuration, it is possible to limit the axial deviation of the pistons when the first and second pistons are driven in the reciprocating motion, to prevent wear of the piston portions, and to extend the life of the device.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a linear compressor showing one embodiment of the present invention.

FIG. 2 is a cross-sectional view for explaining the operation of the apparatus shown in FIG. 1 by moving the first piston 7 to a position near the top dead center.

FIG. 3 is a cross-sectional view for explaining the contents of the operation of the apparatus shown in FIG. 1 by moving the second piston 10 to a position near top dead center.

FIG. 4 is a sectional view of a conventional linear compressor.

FIG. 5 is a conceptual diagram showing a configuration of a closed type refrigeration system.

FIG. 6 is a top view showing the shape of the suspension spring.

[Explanation of symbols]

Reference Signs List 1 housing 2 upper compression chamber 3 lower compression chamber 6 first cylinder 7 first piston 8 first valve mechanism 9 second cylinder 10 second piston 11 second valve mechanism 12 piston shaft 13 movable body (bobbin) 20 suspension spring (plate) 41 first gas bearing portion 42 second gas bearing portion 51 first communication passage 52 second communication passage

Claims (6)

[Claims] 1. A linear compressor for compressing gas in a compression chamber and supplying the compressed gas to the outside, comprising: first and second cylinders provided on both sides in a housing; and reciprocally fitted in the first and second cylinders. 1st and 2nd which are respectively mounted and define the compression chamber in each cylinder.
A piston, a piston shaft having both ends fixed to the first and second pistons, and a bottomed cylindrical movable body integrally fixed to the piston shaft, part of a magnetic circuit including a magnet and a magnetic frame A linear motor that is disposed in the gap formed in the housing and that reciprocates the piston by supplying alternating current of a predetermined frequency to an electromagnetic coil wound around the outer periphery of the movable body; A plate-like piston spring elastically supporting the first and second pistons in a reciprocating manner in the first and second cylinders, respectively; And a gas bearing for regulating the position of the second piston in the axial direction. 2. A first communication passage for supplying a compressed gas from a compression chamber in a first cylinder to a gas bearing portion, and a first communication passage for supplying a compressed gas from a compression chamber in a second cylinder to the gas bearing portion. 2. The linear compressor according to claim 1, further comprising a second communication path. 3. The device according to claim 2, wherein the first communication passage is formed in the first piston and the piston shaft, and the second communication passage is formed in the second piston and the piston shaft. Linear compressor. 4. A gas bearing part is provided in a first cylinder on the back side of the first piston, and controls a position of the first piston in an axial direction, and a gas bearing part on a back side of the second piston. The linear compressor according to any one of claims 1 to 3, further comprising a second gas bearing portion provided on the second cylinder and configured to regulate a position of the second piston in an axial direction. 5. The first and second pistons each have a first
The linear compressor according to any one of claims 1 to 4, wherein the linear compressor is reciprocally inserted into the second cylinder via a minute gap so as to reciprocate. 6. The linear compressor according to claim 5, wherein the minute gap is set to 10 μm or less.