JP2002339863A - Linear compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a linear compressor by minimizing stroke space by a relative movement among a coreless coil 21 and a magnet 22 and yoke 23, and extensively reduce an iron loss generated in a yoke, enhance efficiency and suppress heat generation by bisecting the coreless coil and feeding mutually opposite phase currents. SOLUTION: Elastic support mechanisms 11 and 17 are provided for movably supporting the coreless coil 21 so as to slide in a coil axial direction on a body case 10, and elastic support mechanisms 16 and 17 are provided for movably supporting the magnet 22 and the yoke 23 so as to slide in the coil axial direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear compressor mainly used for equipment such as a freezer and a refrigerator.

[0002]

2. Description of the Related Art Freezers and refrigerators are provided with a compressor for compressing a refrigerant. As this compressor, a rotary compressor that drives a rotary pump by using a motor as a power source is well known. On the other hand, in addition to this, a reciprocating compressor is known (Japanese Patent Laid-Open No. 7-280374). Here, a technique is described in which an alternating current is supplied to an electromagnet disposed in a static magnetic field to cause a piston to reciprocate and vibrate, thereby compressing gas in a cylinder. Such a compressor is called a linear compressor.

FIG. 5 is a longitudinal sectional view of a main part of a conventional linear compressor. Inside the body case 1 is a spring 2
And a pair of left and right pistons 3 supported by the piston.
The piston 3 is configured to fit into a cylinder 4 formed continuously with the main body case 1 and compress the gas inside. A coreless coil 5 is integrated with the piston 3. A magnet 6 is fixed to the inner surface of the main body case 1. The magnetic flux of the magnet 6 is formed so as to be orthogonal to the direction of the drive current flowing through the coreless coil 5. When an alternating current for driving is supplied from a power supply (not shown) to the coreless coil 5, the piston 3 receives a force in the direction of arrow A in the figure according to the direction of the current.

The resonance frequency of the piston 3 is determined depending on the spring constant of the spring 2, the elastic coefficient of the gas contained in the cylinder 4 and a constant determined by the mass of the piston 3. An alternating current having a frequency near the resonance frequency is supplied from a power supply (not shown). Therefore, the piston 3 constantly vibrates at a constant frequency in the direction of arrow A by the electromagnetic force. A compression force and an expansion force are alternately applied to the gas inside the cylinder 4. When the gas flow direction is adjusted by a valve mechanism (not shown), this device operates as a pump. In this linear compressor, the phase difference between the vibrations of the left and right pistons 3 is different by 180 degrees, so that the linear compressors mutually cancel out the vibration energy. Thus, the vibration is absorbed inside the main body case 1 to operate efficiently.

[0005]

Here, the conventional linear compressor has the following problems to be solved.

First, in order to reciprocate the pair of pistons 3, a space for the strokes of both pistons 3 must be secured inside the main body case 1. In order to reduce the stroke and reduce the size of the body case 1 in the vibration direction of the piston 3, it is preferable to increase the driving force of the piston 3 and use the cylinder 4 having a large sectional area. However, in order to increase the driving force of the piston 3, it is necessary to make the winding diameter of the coreless coil 5 large and flow a large current. This is contrary to the purpose of reducing the size and weight. on the other hand,
When the driving force of the piston 3 is reduced, the cylinder 4 having a small area is used.
There is a problem that the size in the vibration direction becomes large.

Second, when an alternating current is supplied to the coreless coil 5 to reciprocate the piston 3, the magnetic flux is guided to the inside of the magnetic material around the cylinder 4 for forming a static magnetic field. Hysteresis loss (iron loss) inevitably occurs in the magnetic material, which causes a problem that the efficiency of the linear compressor is reduced. It should be noted that there is a similar problem with the rotary compressor in that hysteresis loss (iron loss) occurs and efficiency is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide an efficient linear compressor with a reduced size.

[0009]

The invention realized by the embodiments described in the following sections has the following configurations. <Structure 1> A coreless coil supplied with an alternating current for driving from a power supply, an elastic support mechanism for movably supporting the coreless coil slidably in the coil axis direction with respect to the main body case, and integrated with the coreless coil A piston that reciprocates in the coil axis direction together with the coreless coil, a magnet and a yoke that form a magnetic field in the vicinity of the coreless coil in a direction substantially perpendicular to the direction in which the drive current of the coreless coil flows; An elastic support mechanism for movably supporting the yoke slidably in the coil axis direction, integrated with the magnet and yoke, forming a pump in cooperation with the piston, and reciprocating in the coil axis direction together with the magnet and yoke Between the moving cylinder and the inside of the cylinder and the outside of the body case Linear compressor, characterized by comprising: a gas passage formed, the.

<Structure 2> In the linear compressor according to Structure 1, the coreless coil is composed of a first coreless coil and a second coreless coil arranged coaxially and spaced apart in the coil axis direction. And drive currents of opposite phases are supplied to the yoke, and the yoke is provided to the first coreless coil and the second coreless coil.
A linear compressor, wherein magnets that form magnetic fields in directions substantially perpendicular to a direction in which a drive current of each coreless coil flows and opposite to each other are integrated.

<Structure 3> In the linear compressor according to Structure 1, the coreless coils are arranged in the order of a first coreless coil and a second coreless coil which are arranged coaxially and separated from each other in the coil axis direction. A drive current having a phase opposite to that of the second coreless coil is supplied to the first coreless coil and the third coreless coil, and the yoke is supplied to the first coreless coil and the third coreless coil. 3 is a direction substantially perpendicular to the direction in which the drive current of each coreless coil flows,
A first magnet forming a magnetic field in the same direction as each other;
A direction substantially perpendicular to a direction in which a drive current of the coreless coil flows with respect to the second coreless coil,
The second magnet forms a magnetic field in the opposite direction to the first magnet.
A linear compressor characterized by integrating the above magnets.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below in detail with reference to specific examples. <Example 1> FIG. 1A is a longitudinal sectional view of a linear compressor of the present invention cut along an axis, and FIG.
It is sectional drawing which follows a line. The illustrated linear compressor includes a piston 12 supported by a spring 11 inside a main body case 10 and a cylinder 15 supported by a spring 16. The piston 12 is movably supported by a spring 11 so as to be able to reciprocate in the direction of arrow 13. The cylinder 15 is movably supported by a spring 16 so as to be able to reciprocate in the direction of arrow 14. The cylinder 15 is integrated with a yoke 23 described later, and is supported by the main body case 10 via a bearing 17. This bearing 1
A portion including the spring 7 and the spring 16 will be referred to as an elastic support mechanism for supporting the cylinder 15. Piston 1
2 is preferably made of a non-magnetic material. Preferably, the cylinder 15 and the yoke 23 are made of a magnetic material. The bearing 17 may be anything as long as it has good rolling.

An O-ring 18 is interposed between the outer peripheral surface of the piston 12 and the inner surface of the cylinder 15,
The head 12A of the piston 12 is positioned on the shaft of the cylinder 15. This O-ring 18 is
Has the function of freely reciprocating in the direction of arrow 13 and maintaining the airtightness between the cylinder 15 and the piston 12. The portion including the O-ring 18 and the spring 11 will be referred to as an elastic support mechanism of the piston 12. A coreless coil 21 is integrated with the piston 12. An alternating current for driving is supplied to the coreless coil 21 from a power source (not shown). The magnet 22 is fixed to the inner surface of the yoke 23. This magnet 22
A magnetic field is formed between the yoke 23 and the cylinder 15 forming a magnetic circuit. That is, it has a function of forming a magnetic field in a direction perpendicular to the direction in which the drive current of the coreless coil 21 flows. In this figure, for convenience of illustration, the distance between the coreless coil 21 and the magnet 22 and the coreless coil 2
Although the distance between the cylinder 1 and the cylinder 15 is set sufficiently wide, in practice, it is preferable to design such that these distances are set sufficiently small so that the electromagnetic force acts efficiently.

When an alternating current is supplied from a power supply (not shown) to the coreless coil 21 of the linear compressor as described above, the current I flowing through the coreless coil 21 and the magnet 2
An electromagnetic force proportional to the product of the magnetic field H formed by 2 and the length L of the coreless coil 21 existing in the magnetic field is applied in the direction of arrow 13. Since an alternating current is supplied to the coreless coil 21, the cylinder 15 and the piston 12 are periodically approached or separated by this electromagnetic force.
An air chamber 26 is provided for converting the compression and expansion forces of the gas by the action of the piston 12 and the cylinder 15 into a pumping motion for sending out the gas. The air chamber 26 connected to the cylinder 15 by the gas flow path of the pipe 25 closes the valve 27 when the gas is compressed and opens the valve 28 to send out the gas. When the gas expands, the valve 27 is opened and the valve 28 is opened. Close and inhale gas from below. In this way, the gas can be sent to one side by alternately opening and closing the valve 27 and the valve 28.

FIG. 2 is an explanatory diagram of the effect when the above-described linear compressor of the present invention is compared with a conventional one. First, the conventional linear compressor described with reference to FIG. 5 operates by a pair of left and right pistons 3 vibrating with a stroke L across a cylinder 4 as shown in FIG. Here, the operation of only the right piston is analyzed. Assuming that the mass of the piston 3, which is a movable part, is m, and the spring constant due to the gas pressure inside the cylinder or the spring exerting a reaction force against the movement of the piston 3 is k, the resonance frequency is (k / m) ^1/2 Proportional. Therefore, if the exciting current supplied to the coreless coil is set to a value near this resonance frequency, the linear compressor can be efficiently driven. The amplitude L of the piston depends on the power supplied to the coreless coil. The piston on the left is exactly the same.

On the other hand, as shown in FIG. 2B, in the case of the present invention, the movable parts are both the cylinder 15 and the piston 12. The cylinder 15 and the piston 12 receive a force such that they are simultaneously drawn and separated by the electromagnetic force. Therefore, the mass m of the movable part is defined as the sum of the masses of both the cylinder 15 and the piston 12, and a total of a pair of springs which exert a reaction force against the movement of the cylinder 15 and the piston 12 and the gas pressure inside the cylinder is obtained. Assuming that the spring constant is k, the resonance frequency is proportional to (k / m) ^1/2 . Therefore, also in the case of the present invention, the linear compressor can be efficiently driven by setting the exciting current supplied to the coreless coil 21 to a value near this resonance frequency. The amplitude L of the cylinder 15 and the piston 12 depends on the power supplied to the coreless coil 21.

The difference dV between the maximum value and the minimum value of the cylinder volume that changes in one stroke of the piston is the cylinder volume when the interval between the cylinder and the piston is the longest, and the cylinder volume when the cylinder and the piston are the closest. Is the difference from the cylinder volume. Since the volume of the pipe protruding into the cylinder changes with the movement of the cylinder, a more accurate value can be obtained by correcting this.

If the cylinders used in the conventional linear compressor and the linear compressor of the present invention have the same inner diameter, the entire length of the movable part when the cylinder volume has a maximum value and the movable length when the cylinder volume has a minimum value. The difference from the total length of the part does not change. However, the linear compressor of the present invention can sufficiently reduce the overall length of the mechanism including the cylinder and the piston when the cylinder volume takes the maximum value or the minimum value. That is, comparing the two, the conventional linear compressor has a total length in consideration of twice the length L corresponding to the stroke, the length of the cylinder 4 and the length of the piston 3. On the other hand, in the linear compressor of the present invention, one piston 12 and one cylinder 15 are combined, and the length corresponding to the conventional cylinder 4 is unnecessary. Therefore, the piston 1 of the linear compressor of the present invention
The size of the main body case accommodating the cylinder 2 and the cylinder 15 can be reduced to, for example, about two thirds of the conventional device.

FIG. 2C is an external view of a conventional linear compressor, and FIG. 2D is an external view of a linear compressor according to the present invention. As is apparent from these drawings, the linear compressor of the present invention can have the same function as that of the conventional main body case 1 with a sufficiently reduced overall length. Further, as shown in FIG. 1 and the like, the piston 12 and the cylinder 1
5 reciprocate 180 degrees out of phase with each other, and thus cancel each other out of vibration energy. Thus, the vibration force is canceled as a whole, and no large vibration is transmitted to the outside. That is, this portion has the same effect as the conventional technology.

FIG. 3 is a longitudinal sectional view showing a linear compressor according to a second embodiment. The linear compressor shown in this figure has the same configuration as that shown in FIG. 1 except for the coreless coils 31, 32 and the magnets 33, 34. Therefore, the corresponding portions in FIG. 3 are assigned the same reference numerals as those in FIG. 1, and duplicate descriptions are omitted.

As shown in the figure, the linear compressor in this figure includes a pair of coreless coils 31 and 32 integrated with the piston 12. These coreless coils 31
And 32, the excitation currents are supplied in opposite directions in the example of FIG. On the other hand, these coreless coils 31, 32
The magnets 33 and 34 fixed to the yoke 23 so that they face each other have the magnetic polarities opposite to each other. By doing so, the magnet 33,
The magnetic flux formed by 34 intersects coreless coils 31 and 32, as shown by arrow h in the figure. That is, the first coreless coil 31 and the second coreless coil 32 are arranged coaxially with each other, and furthermore, are spaced apart from each other by a predetermined distance in the axial direction of the coil. Then, a magnet 33 is provided for the coreless coil 31.
Are selected so that the direction of the magnetic field formed by the magnet 34 and the direction of the magnetic field formed by the magnet 34 with respect to the coreless coil 32 are opposite to each other.

Therefore, when alternating currents in opposite directions are supplied to the coreless coil 31 and the coreless coil 32, the electromagnetic force acting on each coreless coil becomes in the same direction, and the piston 12 is moved in exactly the same manner as in the example of FIG. It reciprocates in the direction of arrow 13. Here, comparing the example of FIG. 1 with the example of FIG. 3, most of the magnetic flux generated by the alternating current flowing through the coreless coil 21 is in the example of FIG.
Infiltration causes large iron loss. On the other hand, in the example of FIG. 3, the magnetic flux generated by the coreless coil 31 and the magnetic flux generated by the coreless coil 32 cancel each other, so that no large magnetic flux is generated outside. That is, it is possible to sufficiently suppress the iron loss generated by the magnetic flux entering the yoke 23. If the iron loss is reduced, the same driving force as before can be obtained with a smaller driving current, so that the number of turns of the coreless coils 31 and 32 can be reduced,
Alternatively, it is possible to reduce the size of the coreless coil to reduce the size. Further, the magnets 33 and 34 can be reduced in size. Further, if the iron loss generated inside the yoke 23 is reduced and the heat generation is reduced, an extra space for heat dissipation is not required, which also enables downsizing.

FIG. 4 is a sectional view showing a linear compressor according to a third embodiment. The linear compressor shown in this figure has the same configuration as that shown in FIG. 1 except for coreless coils 41, 42, 43 and magnets 44, 45, 46. Therefore, the corresponding portions in FIG. 3 are assigned the same reference numerals as those in FIG. 1, and duplicate descriptions are omitted.

In the piston 12 shown in the figure, three coils 41, 42, 43 are coaxially arranged at a fixed distance. In this example, an alternating current in the same direction is supplied to the coils 41 and 42, and an alternating current in the opposite direction is supplied to the coil 43. Also, a magnet 44 is provided on the yoke 23 side so as to correspond to the coils 41, 42, 43.
45 and 46 are arranged and fixed. Magnet 4
4 and 45 supply magnetic fields in the same direction to the coreless coils 41 and 42. Further, the magnet 46 supplies a magnetic field in the opposite direction to the magnets 44 and 45. In the example of this figure, similarly to the example of FIG. 3, the direction of the electromagnetic force received by the coreless coil 43 by the magnetic field formed by the magnet 46 and the electromagnetic force received by the coreless coils 41 and 42 by the magnetic field formed by the magnets 44 and 45. The direction matches.
Therefore, a force for vibrating the piston 12 in the direction of the arrow 13 is generated in exactly the same manner as in the above examples. At this time, the magnetic flux is generated from the magnet 46 and reaches the magnets 44 and 45 in two parts. Therefore, if the number of turns of the coreless coil 43 is set to twice the number of turns of the coreless coils 41 and 42, each coil receives the same electromagnetic force.

If the number of turns obtained by adding the number of turns of the coreless coils 31 and 32 shown in FIG. 3 is equal to the number of turns of the coreless coil 21 shown in FIG. 1, the same overall electromagnetic force is obtained. If the number of turns obtained by adding the total number of turns of the coreless coils 41, 42, and 43 shown in FIG. 4 is equal to the number of turns of the coreless coil 21 shown in FIG. 1, the same electromagnetic force is obtained as a whole. Further, in the case of the example shown in FIG. 4, the magnetic fluxes generated by the coreless coils 41, 42, and 43 cancel each other out and do not leak to the outside as in the case of the example shown in FIG. Thus, iron loss generated inside can be sufficiently suppressed.
This makes it possible to improve the efficiency and reduce the size.

The present invention is not limited to the above embodiment. The elastic support mechanism for movably supporting the coreless coil 21 slidably in the coil axis direction with respect to the main body case includes:
Not only a spring but also various elastic bodies can be adopted. The same applies to the elastic support mechanism that movably supports the magnet and the yoke so as to be slidable in the coil axis direction. Further, the piston and the cylinder may be arranged at positions where they reciprocate by the electromagnetic force of the coreless coil and the magnet, and their positional relationship, size and number may be freely selected. The configuration of the gas flow path for compressing the gas inside the cylinder is also free. Further, the linear compressor of the present invention described above can be widely used not only in freezers and refrigerators but also in various fields such as gas compressors and decompressors.

[0027]

As described above, the linear compressor according to the present invention has the following effects. First
In addition, an elastic support mechanism for movably supporting the coreless coil in the coil axis direction with respect to the main body case and an elastic support mechanism for movably supporting the magnet and the yoke in the coil axis direction are provided. By the relative movement of the magnet and the yoke, the stroke space can be reduced, and the size of the linear compressor can be reduced. Further, as described in the specific example 2, the coreless coil is composed of a pair of coils arranged coaxially and separated from each other in the coil axis direction. Cancel each other, and the iron loss generated inside the yoke can be greatly reduced. Therefore, the efficiency is improved and the heat generation can be suppressed,
It is possible to further reduce the size of the linear compressor. Further, as described in the specific example 2, if a magnet that forms a predetermined magnetic field using three coreless coils arranged coaxially and spaced apart in the coil axis direction in order is adopted, As in the case of 2, the efficiency can be increased and heat generation can be suppressed, and the magnet can be reduced in size by effectively utilizing the magnetic field, so that the linear compressor can be further reduced in size.

[Brief description of the drawings]

FIG. 1A is a longitudinal sectional view of a linear compressor of the present invention cut along an axis, and FIG. 1B is a sectional view taken along the line BB.

FIG. 2 is an explanatory diagram of an effect when the linear compressor of the present invention is compared with a conventional compressor.

FIG. 3 is a longitudinal sectional view showing a linear compressor according to a second embodiment.

FIG. 4 is a cross-sectional view illustrating a linear compressor according to a third embodiment.

FIG. 5 is a longitudinal sectional view of a main part of a conventional linear compressor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Main body case 11 Spring 12 Piston 15 Cylinder 16 Spring 17 Bearing 21 Coreless coil 22 Magnet 23 Yoke 25 Pipe 26 Air chamber 27, 28 Valve mechanism

Continuation of the front page (72) Inventor Osamu Kokubo 2-1-1, Oda Ei, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Inside Showa Electric Wire & Cable Co., Ltd. No. 1 Inside Showa Electric Wire & Cable Co., Ltd. (72) Inventor Sukehiro Akama 2-1-1 Oda Sakae, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture Inside Showa Electric Wire & Cable Co., Ltd. 2-1-1, Showa Electric Wire & Cable Co., Ltd. F-term (reference) 3H076 AA02 AA03 BB21 BB31 BB38 BB43 CC06 5H633 BB02 BB03 GG02 GG06 GG09 GG13 HH02 HH03 HH07 HH13 JA09

Claims (3)

[Claims] A coreless coil supplied with an alternating current for driving from a power supply; an elastic support mechanism for movably supporting the coreless coil in a coil axial direction with respect to a main body case; A piston that reciprocates in the coil axis direction together with the coreless coil; a magnet and a yoke that form a magnetic field near the coreless coil in a direction substantially perpendicular to a direction in which a drive current of the coreless coil flows; And an elastic support mechanism that slidably supports the yoke in the coil axis direction, and is integrated with the magnet and the yoke, forms a pump in cooperation with the piston, and forms a pump in the coil axis direction together with the magnet and the yoke. A reciprocating cylinder, inside the cylinder and outside the body case A gas flow path formed between the linear compressor and the linear compressor. 2. The linear compressor according to claim 1, wherein the coreless coil and the second coreless coil are coaxially arranged and separated from each other in a coil axial direction.
And drive currents of opposite phases are supplied to the yoke. The yoke is substantially perpendicular to the direction in which the drive current of each coreless coil flows with respect to the first coreless coil and the second coreless coil. A linear compressor, wherein magnets for forming magnetic fields in opposite directions are integrated. 3. The linear compressor according to claim 1, wherein the coreless coils are arranged coaxially with one another and sequentially spaced apart in a coil axial direction. The first coreless coil and the third coreless coil are supplied with a drive current having a phase opposite to that of the second coreless coil, and the yoke is supplied with the first coreless coil and the third coreless coil. A first magnet forming a magnetic field in a direction substantially perpendicular to the direction in which the drive current of each coreless coil flows, and forming a magnetic field in the same direction with respect to the coreless coil; A second magnet that forms a magnetic field in a direction substantially perpendicular to the direction in which the drive current of the coreless coil flows and that is opposite to the first magnet is integrated with the first magnet. Linear compressor, characterized by that.