JP2000023441A - Linear motor and linear compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear motor improved in efficiency by suppressing decrease of the magnetic fluxes passing through the gaps formed in the magnetic frame of a mobile section and a compressor using the motor. SOLUTION: The magnetic gap 8 in a magnetic frame 2 is made smaller by forming a yoke 9 set up in a space 8 opposingly to permanent magnets 5 arranged inside the outer yoke 2b of a magnetic frame 2 of a magnetic material and, at the same time, winding a coil around the thin-wall section 9b of the yoke 9 in a striped state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear motor having a structure in which a coil is arranged in a gap between magnetic frames and a coil is moved by applying a current to the coil, and a compressed gas is generated by using the linear motor. Related to externally supplied compressors.

[0002]

2. Description of the Related Art In recent years, a linear compressor has been developed as a device for compressing and supplying a refrigerant gas in a refrigeration system or the like. This linear compressor is driven by a linear motor, and a schematic configuration of the linear motor will be described below.

FIG. 3 is an exploded perspective view showing a configuration example of a general linear motor, and FIG. 4 is a cross-sectional view thereof.

[0004] As shown in FIG.
Is composed of a fixed part 101 and a movable part 110 movable in the vertical direction in the figure with respect to the fixed part 101.

[0005] The fixed portion 101 is a magnetic frame 1 made of a magnetic material.
02 and a cylindrical permanent magnet 107 fixed to the magnetic frame 102.

The magnetic frame 102 is made of a magnetic material such as low carbon steel and has a cylindrical outer yoke 102a and a cylindrical inner yoke 102b having an outer diameter smaller than the inner diameter of the outer yoke 102a. And a bottom yoke 102c connecting one ends of the yokes 102a and 102b. The permanent magnet 107 is connected to the outer yoke 102 of the magnetic frame 102.
a is fixed to the inner peripheral surface, and forms a magnetic circuit with the magnetic frame 102. And, by this magnetic circuit, the permanent magnet 1
The magnetic flux A is generated in a gap 108 between the inner yoke 102 and the inner yoke 102b.

The movable portion 110 has a cylindrical bobbin 109 with a bottom and a shaft portion 112 projecting from the bottom of the bobbin 109 and penetrating the inside of the inner yoke 102b of the magnetic frame 102.
And a coil 111 wound around the bobbin 109. The coil 111 is provided in the gap 10 of the magnetic frame 102.
At 8, it is arranged at a position facing the permanent magnet 107 so as to be orthogonal to the magnetic flux A.

In such a configuration, the coil 1
When a current is applied to the coil 11, an upward or downward force acts on the coil 111 according to the direction of the current,
The movable part 110 moves in the direction of the force.

[0009]

However, in the linear motor having such a configuration, the magnetic permeability of the coil 111 is low, and the magnetic flux A is reduced by the coil 111, so that the driving efficiency of the motor is reduced. is there.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a high-efficiency linear motor and a compressor using the same, which suppress a decrease in the magnetic flux A due to the coil 111. And

[0011]

A linear motor according to the present invention comprises a cylindrical outer yoke, an inner yoke arranged inside the outer yoke with a gap, one end of the outer yoke and one end of the inner yoke. A cylindrical coil is disposed in the gap between the magnetic frame composed of the bottom yoke to be connected and the permanent magnet fixed to the inner surface of the outer yoke or the outer surface of the inner yoke, and the movable portion supports the coil. The motor is characterized in that the coil is divided and arranged with the magnetic material interposed therebetween.

With such a configuration, the magnetic flux from the permanent magnet concentrates on the magnetic material having a higher magnetic permeability than the coil having a lower magnetic permeability and reaches the yoke opposed thereto.

Further, the linear motor according to the present invention is characterized in that the magnetic frame is fixed to a fixed portion, and the movable portion is supported by the fixed portion via an elastic member.

In such a configuration, when an alternating current having a predetermined frequency is supplied to the coil, the movable portion reciprocates according to the frequency.

Further, the linear motor of the present invention includes a cylindrical bobbin having a movable portion made of a magnetic material, and a thick portion and a thin portion are alternately formed on the side surface of the bobbin, and a coil is formed in the thin portion. It is characterized by being arranged.

With this configuration, the magnetic flux from the permanent magnet concentrates on the thicker portion side than the thinner portion on which the coil is disposed and reaches the opposing yoke. The magnetic permeability of the entire portion becomes higher.

Further, the linear compressor of the present invention has a cylinder provided in a housing, a piston reciprocatingly fitted in the cylinder and defining a compression chamber in the cylinder, and a reciprocating drive of the piston. Linear motor, and a resilient member that returns the piston away from the neutral point to the neutral point.In the linear compressor, the linear motor is fixed to the cylinder and has a magnetic frame formed with a gap, and the magnetic frame The permanent magnet includes a permanent magnet fixed to the gap, and a coil disposed at a position facing the permanent magnet of the magnetic frame and fixed to the piston, and the coil is divided with the magnetic body interposed therebetween.

With this configuration, the magnetic flux from the permanent magnet concentrates on the magnetic body having higher magnetic permeability than the coil having lower magnetic permeability, passes through the magnetic frame, and reaches the opposing portion of the magnetic frame. I do. When an alternating current having a predetermined frequency is supplied to the coil, the piston moves from the neutral point due to the action of the electromagnetic force, and an elastic force toward the neutral point acts on the moved piston by an elastic member. As a result, the piston reciprocates to pressurize or depressurize the compression chamber of the cylinder.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described in detail with reference to the drawings. In this embodiment, a case will be described in which the linear motor is applied to a linear compressor of a refrigeration system.

FIG. 1 is a system block diagram showing a schematic configuration of a refrigeration system according to the present embodiment.
FIG. 2 is a sectional view illustrating a schematic configuration of a linear compressor used in the refrigeration system.

As shown in FIG. 1, the refrigeration system according to this embodiment includes a linear compressor 21 and a condenser 2.
2. This is a hermetic refrigeration system in which an expansion valve 23 and an evaporator 24 are connected by a gas flow path pipe 25. The linear compressor 21 sucks the refrigerant gas vaporized by the evaporator 24 through the gas passage pipe 25, compresses the refrigerant gas to a high pressure, and discharges the high-pressure refrigerant gas to the condenser 22 through the gas passage pipe 25. Has been used as

As shown in FIG. 2, the linear compressor 21 includes a cylinder 3 for compressing the refrigerant gas sucked from the evaporator 24, a piston 5 for forming a compression chamber 4 in a space inside the cylinder 3, A linear motor 6 is provided as a drive source for driving the piston 5 back and forth.

The cylinder 3 is made of a stainless steel having a cylindrical shape, and a valve mechanism 12 is provided on an upper portion thereof.
The compression chamber 4 inside the cylinder 3 is provided with the valve mechanism 12.
Is connected to a gas flow path pipe 25 outside the housing 1 through the housing 1. That is, the valve mechanism 12 includes a suction valve 12 a that allows only the suction of the refrigerant gas from the evaporator 24 through the gas flow path pipe 25 and discharge of the refrigerant gas to the condenser 22 through the gas flow path pipe 25. And a discharge valve 12b that permits only the discharge valve 12b. The suction valve 12 a is a valve that causes a gas to flow in the direction of the compression chamber 4 by a pressure difference between the gas passage pipe 25 on the low pressure side and the refrigerant gas in the compression chamber 4.
b, the compression chamber 4 and the gas passage pipe 2 on the high pressure side are opened so that the refrigerant gas pressure in the compression chamber 4 becomes higher than a predetermined pressure.
5 is a valve that causes the gas to flow out to the gas passage pipe 25 on the high pressure side by the pressure difference between the refrigerant gas and the refrigerant gas 5. The suction valve 12
a and the discharge valve 12b are both urged by a leaf spring (not shown).

The piston 5 has a cylindrical shape with a diameter slightly smaller than the inner diameter of the cylinder 3, and a piston ring 13 is fixed to the peripheral surface of the cylinder 5 so as to close a gap with the inner peripheral surface of the cylinder 3.

The linear motor 6 includes a fixed portion fixed to the bottomed cylindrical housing 1 and a movable portion that can reciprocate with respect to the fixed portion.

The fixed portion includes a magnetic frame 2 fixed to the upper opening of the housing 1 and a permanent magnet 7 fixed to the magnetic frame 2. The magnetic frame 2 is made of a magnetic material such as low-carbon steel, and has a cylindrical outer yoke 2a, a cylindrical inner yoke 2b having an outer diameter smaller than the inner diameter of the outer yoke 2a, and both yokes 2a. And a bottom yoke 2c that connects one end of the yoke 2b.
A gap 8 is formed in a region surrounded by b and 2c. A cylindrical permanent magnet 7 is fixed along the inner peripheral surface of the outer yoke 2 a of the magnetic frame 2. Thereby, the permanent magnet 7
And the magnetic frame 2 constitute a magnetic circuit.
Occurs.

On the other hand, the movable portion includes a coil spring 10 fixed to the center of the bottom of the housing 1 and a cylindrical bobbin 9 having a bottom which is elastically supported by the coil spring 10.
And The bobbin 9 is made of low carbon steel, and its peripheral surface is fitted between the permanent magnet 5 and the inner yoke 2b in the gap 8 of the magnetic frame 2 so as to be orthogonal to the magnetic flux B. The peripheral surface of the bobbin 9 is provided with a plurality of grooves each having a uniform depth along the circumferential direction at a position facing the permanent magnet 5, and the grooves provide a thick portion 9 a on the peripheral surface of the bobbin 9. And a thin portion 9b are formed. The electromagnetic coil 11 is divided and wound around the thin portion 9b. Further, a shaft 14 is fixed to the center of the bobbin 9, and the piston 5 is fixed via the shaft 14.

The linear compressor 21 having such a configuration is described.
, When a current of a predetermined frequency is applied to the electromagnetic coil 11 via a lead wire (not shown), the movable portion formed of the electromagnetic coil 11 and the bobbin 9 is acted on by the action of the magnetic flux B passing through the gap 8 and Electromagnetic force acts in the direction. When the movable part rises by this electromagnetic force, the movable part falls by the elastic force of the coil spring 10. By repeating this, the piston 5 reciprocates in the cylinder 3. Accordingly, in the compression chamber 4, when the piston 5 moves upward, the gas pressure increases, and when the piston 5 moves downward, the gas pressure decreases, and a gas pressure of a predetermined cycle is generated.

Then, for this predetermined period of gas pressure,
By controlling the valve mechanism 12, the refrigerant gas vaporized in the evaporator 24 is sucked into the compression chamber 4 through the gas passage pipe 25 and compressed, and the high-pressure refrigerant gas is condensed through the gas passage pipe 25. Is discharged to the vessel 22.

Here, in the linear motor 6, as shown in the sectional view of FIG. 2, the winding thickness Lc of the coil is set to 4/5 of the distance Lg between the permanent magnet 5 and the inner yoke 2b. In addition, since the area ratio between the thick portion 9a of the bobbin 9 and the electromagnetic coil 11 is 1: 1, the Carter coefficient Kc is about 1.2 in consideration of the low magnetic permeability of the electromagnetic coil 11. . Then, the magnetic gap G of the gap 8 is calculated by the following equation 1 and becomes approximately 0.24 Lg.

[0031]

(Equation 1) Accordingly, the magnetic gap G of the gap 8 is approximately １ ／ of the gap Lg when the electromagnetic coil 11 is continuously wound around the bobbin 9 made of a non-magnetic material as in the related art.
That is, the magnetic flux becomes approximately four times.

On the other hand, since the area ratio between the thick portion 9a of the bobbin 9 and the electromagnetic coil 11 is set to 1: 1, when the same diameter winding is used, the number of turns of the electromagnetic coil 11 is reduced to 1/2. It has become. Note that, as the number of turns of the electromagnetic coil 11 is reduced to １ ／, the resistance of the electromagnetic coil 11 is also reduced to １ ／.

As a result, even if the number of turns is 1/2, the magnetic flux is quadrupled, so that the current required to obtain the same torque as in the prior art can be reduced to 1/2.

As described above, according to the present embodiment, the yoke 9 disposed in the gap 8 facing the permanent magnet 5 disposed inside the outer yoke 2b of the magnetic frame 2 is made of a magnetic material. At the same time, since the coil 11 is wound in a striped shape around the thin portion 9b on the peripheral surface, the magnetic gap generated in the gap 8 of the magnetic frame 2 is reduced, and the driving efficiency of the linear motor and the linear compressor using the same is improved I do.

Further, since the yoke 9 is elastically supported on the housing 1 by the coil spring 10, the yoke 9 can be moved only in one direction up or down.
Can be driven back and forth, so that the yoke 9 can be easily driven back and forth.

The bobbin 9 has a thick portion 9a and a thin portion 9b.
By disposing the electromagnetic coil 11 in each of the thin portions 9b, it is possible to eliminate variations in the intervals and shapes of the electromagnetic coils 11.

In this embodiment, a case has been described in which the linear motor is applied to a one-piston linear compressor having one cylinder. However, for example, two cylinders are disposed vertically and the upper end of the shaft and Even when the present invention is applied to a two-piston type linear compressor in which a piston is disposed at each lower end and a compression chamber is formed in both cylinders, the same operation and effect as a one-piston type linear compressor can be obtained.

In this embodiment, the coil spring 10 is used as the elastic member. However, the present invention is not limited to this, and a suspension spring or the like may be used.

[0039]

According to the present invention, since the coil of the movable portion disposed opposite to the permanent magnet fixed to the magnetic frame is divided and arranged with the magnetic material interposed therebetween, the magnetic field generated in the gap between the magnetic frames is reduced. Gap can be reduced,
The driving efficiency of the linear motor and the linear compressor using the same can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of a refrigeration system according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a schematic configuration of a linear compressor applied to the refrigeration system of FIG.

FIG. 3 is an exploded perspective view illustrating a schematic configuration of a conventional linear motor.

FIG. 4 is a sectional view of the linear motor of FIG. 3;

[Explanation of symbols]

 1: Housing 2: Magnetic frame 3: Cylinder 4: Compression chamber 5: Piston 6: Linear motor 7: Permanent magnet 8: Gap 9: Bobbin 10: Coil spring 11: Electromagnetic coil 12: Valve mechanism 21: Linear compressor

Claims (4)

[Claims] A cylindrical outer yoke, an inner yoke disposed inside the outer yoke via a gap, a bottom yoke connecting one end of the outer yoke and one end of the inner yoke, and the outer yoke A linear motor in which a cylindrical coil is disposed in a gap between a magnetic frame composed of a permanent magnet fixed to an inner surface of the inner yoke or an outer surface of the inner yoke and a movable portion supports the coil, 2. The linear motor according to claim 1, wherein the linear motor is divided and arranged with the body interposed therebetween. 2. The linear motor according to claim 1, wherein the magnetic frame is fixed to a fixed part, and the movable part is supported by the fixed part via an elastic member. 3. The movable portion includes a cylindrical bobbin made of a magnetic material, and a thick portion and a thin portion are alternately formed on a side surface of the bobbin, and the coil is disposed in the thin portion. 3. The linear motor according to claim 1, wherein: 4. A cylinder provided in a housing,
A piston that is reciprocally fitted in the cylinder, defines a compression chamber in the cylinder, a linear motor that reciprocates the piston, and an elastic member that returns the piston away from the neutral point to the neutral point. Wherein the linear motor is fixed to the cylinder, and a magnetic frame having a gap formed therein, a permanent magnet fixed to the gap between the magnetic frames, and the permanent magnet of the magnetic frame. A linear compressor, comprising: a coil disposed at an opposing position; and a coil fixed to the piston, wherein the coil is divided and disposed with a magnetic material interposed therebetween.