JPH1077964A - Linear compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain high efficiency and long service life of a device by providing guide parts having rolling bearings at the inner peripheral surface and holding a piston shaft slidably to the rolling bearings. SOLUTION: First and second coil springs 10, 11 are provided to elastically support a movable body (bobbin) 8 of bottomed cylidner shape opened on the piston 5 side, and a piston 5 in a reciprocating state. A first guide part 12 and a second guide part 13 respectively have rolling bearings 21, 22 at the inner peripheral surface and hold a piston shaft 9 in a vertically slidable state so as to specify the linear moving direction of the piston 5. A micro clearance is thereby provided between the piston and a cylinder to realize clearance seal. There is therefore no risk of causing lowering of operating efficiency caused by frictional loss at the time of reciprocating motion of the piston 5, lowering of the service life of a device caused by the wear of a gas sealing member provided at the piston, pollution of refrigerant caused by abrasive powder, and the like.

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. 3, 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
7 and the magnetic frame 102, a magnetic field B is applied to a cylindrical gap 108 concentric with the center of the cylinder 103.
Generate. The gap 108 has a piston 10 at the center.
Cylindrical movable body 1 made of resin integrally fixed to 5
And a coil spring 110 for elastically supporting the movable body 109 and the piston 105 in a reciprocable manner.
Are 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
When an alternating current having a predetermined frequency is supplied 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 1
05 is reciprocated in the cylinder 103 and the compression chamber 104
At a predetermined cycle.

On the other hand, a typical refrigeration system is shown in 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 125 is known. The refrigerant gas vaporized in 124 is sucked through a gas flow path 125 and compressed to a high pressure, and the high pressure refrigerant gas is discharged to a condenser 122 through a gas flow path 125.

For this reason, as shown in FIG.
4 includes a valve mechanism 1 provided at the upper end of the cylinder 103.
A gas flow path 125 outside the housing 101 is connected through the connection 12. The valve mechanism 112 includes a suction valve 112 a that allows only the suction of the refrigerant gas from the evaporator 124 through the gas flow path 125, and a condenser 12 through the gas flow path 125.
And a discharge valve 112b that permits only discharge of the refrigerant gas to the discharge valve 112. The suction valve 112a is operated by the pressure difference between the refrigerant gas in the gas passage 125 on the low pressure side and the compression chamber 104,
This is a valve that allows gas to flow in the direction of the compression chamber 104. The discharge valve 112b is opened by the pressure difference of the refrigerant gas between the compression chamber 104 and the gas passage 125 on the high pressure side so as to open when the pressure of the refrigerant gas 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 flow path 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.

[0008]

In the conventional linear compressor 121, the linear motor 106 drives the piston 105 to move up and down while sliding in the cylinder 103, so that a kind of sliding bearing is provided between the piston and the cylinder. Is configured.

However, in the above-mentioned conventional configuration, due to the problem of machining accuracy and distortion of the electromagnetic force of the electromagnetic coil 111,
A force (radical force) is generated in a direction perpendicular to the piston movement direction. If the radical force is large, the operating efficiency is reduced due to frictional loss, and the life of the device is shortened due to the wear of the gas seal provided on the piston 105. There is a possibility that the cooling agent may be deteriorated or contaminated by the abrasion powder.

The present invention has been made in view of the above, and an object of the present invention is to provide a linear compressor which achieves high efficiency and long life of the apparatus.

[0011]

A first linear compressor of the present invention includes a cylinder provided in a housing,
It is reciprocally playable inserted into the cylinder via a minute gap,
A piston that defines a compression chamber in a cylinder, a piston shaft having one end fixed to the piston, and a bottomed cylindrical movable body integrally fixed to the piston shaft, comprising a magnet and a magnetic frame. A linear motor, which is disposed in a gap formed in a part of the circuit and reciprocates the piston by supplying alternating current of a predetermined frequency to an electromagnetic coil wound around the outer periphery of the movable body, and a rolling bearing on the inner peripheral surface. Have
A guide portion for slidably holding the piston shaft on the rolling bearing.

By using this configuration, the piston shaft is directly supported by the rolling bearing, and the direction of linear movement of the piston is defined, so that a clearance seal can be realized between the piston and the cylinder.

As a specific configuration, the minute gap is
This is a range where a gas seal is formed between the piston and the cylinder as the piston reciprocates, and is preferably set to 5 μm or less.

The guide section includes a first guide section provided on the cylinder on the back side of the piston, and a second guide section provided on the bottom surface of the housing. The first guide section and the movable body are provided. A first coil spring provided between the second guide portion and the movable body; and a second coil spring provided between the second guide portion and the movable body.

By using this configuration, it becomes easy to control the stroke center position of the piston to be constant, and it is possible to set the spring constant within the same device size larger than before.

In the second linear compressor of the present invention, a rolling bearing is provided on a cylinder or a piston, and the piston is reciprocated along the cylinder via the rolling bearing.

By using this configuration, the piston can slide along the cylinder via the rolling bearing, and there is no need to provide a gas seal member on the piston.
A decrease in operating efficiency due to friction loss between the piston and the cylinder during reciprocation of the piston is prevented.

As a specific configuration, the piston shaft is freely inserted so as to be reciprocally movable, and a spring receiving portion provided on a cylinder on the back side of the piston, and a first receiving portion provided between the spring receiving portion and the movable body. A coil spring,
A second coil spring provided between the bottom surface of the housing and the movable body.

By using this configuration, it is easy to control the stroke center position of the piston to be constant, and it is possible to set the spring constant within the same device size larger than before.

[0020]

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. 4, 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 is a bottomed cylindrical body, and a magnetic frame (yoke) 2 made of low carbon steel is provided on the upper end side.
Are formed. A cylinder fitting hole 3 extending vertically extends through the center of the yoke 2, and a bottomed cylindrical cylinder 4 made of stainless steel is fitted into the cylinder fitting hole 3.

In the cylinder 4, a piston 5 is reciprocally inserted through a minute gap so as to reciprocate. The cylinder 4 and the piston 5 define a compression chamber 6 serving as a compression space for refrigerant gas. Here, the minute gap is set in a range in which a gas seal is formed between the piston 5 and the cylinder 4 as the piston 5 reciprocates, and specifically, is set to 5 μm or less. In the present embodiment, the thickness is set to 5 μm.

The cylinder 4 has an external gas flow path 1.
25 and a valve mechanism 7 for connecting to the
Reference numeral 7b denotes a suction valve for sucking the refrigerant gas vaporized in the evaporator 124 through the gas flow path 125, and 7b denotes a high pressure refrigerant gas compressed in the compression chamber 6 through the gas flow path 125 to the condenser 122. Discharge valve for discharging to

The piston 5 has a bottomed cylindrical movable body (bobbin) 8 made of resin, which is a lightweight non-magnetic material, and having the piston 5 side open, which is integrally fixed to a piston shaft 9 of the piston 5. And first and second coil springs 10 and 11 for elastically supporting the bobbin 8 and the piston 5 so as to be able to reciprocate. The first coil spring 10 is connected to the piston shaft 9
, One end of which is in contact with the bobbin 8, and the other end of which is in contact with the first guide portion 12 provided in the cylinder 4. The second coil spring 11 is connected to a second guide 13 provided at the center of the bottom surface of the housing 1 and a bobbin 8.
And is fixed between them.

The piston 5 and the bobbin 8 are drivingly connected to a linear motor 14 as a driving source for reciprocating the piston 5 and the bobbin 8. An annular recess 15 is formed in the yoke 2 so as to be concentric with the cylinder fitting hole 3.
An annular permanent magnet 16 is mounted on the outer side surface 15a of the motor 5 with a predetermined gap S between the outer surface 15a and the inner side surface 15b.
Four magnetic circuits 17 are configured. This magnetic circuit 17
As a result, a magnetic field having a predetermined strength is generated in the gap S between the magnet 16 and the inner side surface of the recess 15.

The bobbin 8 is disposed so as to be able to reciprocate in the gap S. An electromagnetic coil 18 is wound around the outer periphery of the bobbin 8 at a position facing the magnet 16, and a lead wire is provided. By passing an alternating current of a predetermined frequency (60 Hz in the present embodiment) through the coil 1 (not shown) by the action of a magnetic field passing through the gap S.
The piston 5 is reciprocated in the cylinder 4 by driving the bobbin 8 and the bobbin 8, and a gas pressure of a predetermined cycle is generated in the compression chamber 6.

The first guide portion 12 and the second guide portion 13
Has rolling bearings 21 and 22 on its inner peripheral surface, respectively, and holds the piston shaft 9 slidably in the vertical direction. Here, the rolling bearings 21 and 22 are linear motion rolling bearings, and in this embodiment, a ball spline LSAG8 manufactured by IKO is used. However, the linear motion rolling bearing to be used is an example, and another type of ball spline or a slide bush may be used. As a result, the friction coefficient (μ = 0.0) is smaller than the friction coefficient (μ = 0.01 to 0.1) of the conventional plain bearing.
The linear motion of the piston shaft 9 is supported by the rolling bearing of 01 to 0.006).

As described above, by disposing the first and second coil springs 10 and 11 on both sides via the bobbin 8, the stroke center position of the piston 5 can be easily controlled to be constant and the spring can be easily controlled. The constant can be increased and the size of the device can be reduced.

The piston shaft 9 is mounted on the rolling bearing 2.
Since the linear movement direction of the piston 5 is defined by being directly supported by the pistons 1 and 22, there is a minute gap between the piston and the cylinder as described above, and a clearance seal can be realized. Therefore, there is no risk of causing a reduction in operating efficiency due to friction loss when the piston 5 reciprocates, a reduction in the life of the device due to wear of the gas seal member provided in the piston 5, and contamination of the refrigerant by abrasion powder.

Next, another embodiment of the present invention will be described with reference to FIG. Here, the difference from the embodiment of FIG. 1 described above is that instead of holding the piston shaft 9 slidably on the rolling bearings 21 and 22 of the first guide portion 12 and the second guide portion 13, the cylinder 4 Is provided with a rolling bearing 31, and the piston 5 is reciprocated along the cylinder 4 via the rolling bearing 31. Then, the first coil spring 10 is provided between the bobbin 8 and the spring receiving portion 32 provided on the cylinder 4 on the rear side of the piston 5, and the second coil spring 11 is provided between the center of the bottom surface of the housing 1 and the bobbin 8. It is provided between. still,
The same components as those in the embodiment of FIG. 1 are denoted by the same reference numerals, and detailed description of these portions will be omitted. Here, a ball spline or slide bush type direct-acting rolling bearing is used as the rolling bearing 31 as in the case of the embodiment of FIG. However, the rolling bearing 31 to be used is disposed near the stroke center of the piston 5 so that the gas in the compression chamber 6 does not leak through the rolling bearing due to the reciprocating motion of the piston 5.

Therefore, instead of sliding the piston 5 along the cylinder 4 via the slide bearing as in the conventional case,
The piston 5 can be slid along the cylinder 4 via the rolling bearing, and the operating efficiency is reduced due to friction loss when the piston 5 reciprocates, and the device life is reduced due to wear of the gas seal member provided on the piston 5. There is no risk of causing a decrease in the temperature and contamination of the refrigerant by the wear powder. Further, similarly to the case of the embodiment of FIG. 1, the stroke center position of the piston 5 can be easily controlled to be constant, the spring constant can be increased, and the size of the apparatus can be reduced.

In this embodiment, the case where the rolling bearing 31 is provided on the cylinder 4 has been described. However, a rolling bearing may be provided on the peripheral surface of the piston 5. The description of the above embodiment is for the purpose of describing the present invention, and should not be construed as limiting the invention described in the claims or reducing the scope thereof. In addition, the configuration of each part of the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made within the technical scope described in the claims.

For example, the case where the piston 5 and the bobbin 8 are formed separately has been described. However, the piston 5 and the bobbin 8 may be formed as one body, or the permanent magnet 16 may be fixed to the inner side surface of the yoke 2. In addition, the housing 1, the yoke 2, and the cylinder 4 may be constituted by the same body. However, in this case, in order to form the magnetic circuit 14, the yoke 2 must be formed of the same material.

[0034]

As described above, according to the present invention, the operating efficiency is reduced due to friction loss during reciprocation of the piston, the life of the device is reduced due to wear of the gas seal member provided on the piston, and the refrigerant due to abrasion powder is generated. There is no possibility of causing contamination of the linear compressor, and the efficiency and the life of the linear compressor can be increased.

[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 of a linear compressor showing another embodiment of the present invention.

FIG. 3 is a sectional view of a conventional linear compressor.

FIG. 4 is a conceptual diagram showing a configuration of a closed refrigeration system.

[Explanation of symbols]

 Reference Signs List 1 housing 2 yoke (magnetic frame) 3 cylinder fitting hole 4 cylinder 5 piston 6 compression chamber 7 valve mechanism 8 movable body (bobbin) 9 piston shaft 10 first coil spring 11 second coil spring 12 first guide portion 13 second Guide portion 14 Linear motor 15 Concave portion 16 Permanent magnet 17 Magnetic circuit 18 Electromagnetic coil 21, 22 Rolling bearing 31 Rolling bearing 32 Spring receiving portion

Claims (6)

[Claims] 1. A cylinder provided in a housing, and is reciprocally inserted into the cylinder via a small gap so as to be reciprocable.
A piston defining a compression chamber in the cylinder, a piston shaft having one end fixed to the piston, and a bottomed cylindrical movable body integrally fixed to the piston shaft, the magnet comprising a magnet and a magnetic frame A linear motor that is disposed in a gap formed in a part of the circuit and that reciprocates a piston by supplying alternating current of a predetermined frequency to an electromagnetic coil wound around the outer periphery of the movable body; and a rolling bearing on the inner peripheral surface. And a guide portion for slidably holding the piston shaft on the rolling bearing. 2. The linear compressor according to claim 1, wherein the minute gap is set in a range where a gas seal is formed between the piston and the cylinder as the piston reciprocates. 3. The linear compressor according to claim 2, wherein said minute gap is set to 5 μm or less. 4. The guide section comprises a first guide section provided on a cylinder on the back side of the piston, and a second guide section provided on a bottom surface of the housing, wherein the first guide section and the movable body are provided. 4. The device according to claim 1, further comprising: a first coil spring provided therebetween; and a second coil spring provided between the second guide portion and the movable body. 5. Linear compressor. 5. A cylinder provided in a housing, a piston reciprocally fitted in the cylinder and defining a compression chamber in the cylinder, and a piston shaft having one end fixed to the piston. An electromagnetic coil wound around an outer periphery of the movable body, wherein a bottomed cylindrical movable body integrally fixed to the piston shaft is disposed in a gap formed in a part of a magnetic circuit including a magnet and a magnetic frame. A linear motor for reciprocatingly driving a piston by supplying alternating current at a predetermined frequency to the cylinder, wherein a rolling bearing is provided on the cylinder or piston, and the rolling bearing is provided on the cylinder or piston. A linear compressor characterized in that a piston is reciprocated along a cylinder via a cylinder. 6. A spring receiving portion provided on a cylinder on the back side of the piston, wherein the piston shaft is freely inserted so as to be able to reciprocate, a first coil spring provided between the spring receiving portion and a movable body. The linear compressor according to claim 5, further comprising a second coil spring provided between the bottom surface of the housing and the movable body.