JP2007291991A - Vibration type compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vibration type compressor capable of reducing contact between a piston and a cylinder by a simple structure without providing a mechanical supporting part. <P>SOLUTION: A moving member of a liner motor is provided with supporting coils 107 wound independently for each outer yoke 104 for controlling the position of the piston 102 in the radial direction, the piston 102 is constituted of an inner yoke 102a, a main magnet 102b, and a side magnet 102c, and current flowing to the supporting coil 107 is controlled. Thereby, suction force acting on the inner yoke 102a is adjusted, and the piston 102 and the cylinder 103 are maintained in a non-contact state while securing a gap between the piston 102 and the cylinder 103. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vibration type compressor, and is particularly suitable for application to a vibration type compressor used in a refrigerator such as a Stirling refrigerator.

When cooling scientific instruments and test equipment, Stirling refrigerators that are energy efficient, lightweight, compact, and environmentally friendly are used.
FIG. 6 is a cross-sectional view showing a schematic configuration of a conventional Stirling refrigerator (Patent Document 1).
In FIG. 6, the Stirling refrigerator 100 </ b> A is provided with a cylinder 3 including a piston 1 that performs linear reciprocating motion and a displacer 2, and a rod 2 is formed on the displacer 2. The piston 1 is formed with a sliding hole 1a disposed at the center in the axial direction, and the rod 2a formed in the displacer 2 passes through the sliding hole 1a. Here, the piston 1 and the displacer 2 are provided so as to be smoothly slidable with respect to the inner peripheral sliding surface 3 a of the cylinder 3.

Further, central portions of the piston support spring 5 and the displacer support spring 6 are fixed to the upper portion of the rod 2 a formed on the displacer 2. The piston support spring 5 and the displacer support spring 6 have a spiral disk type panel shape.
The piston 1 is elastically fixed to the casing 15 by a piston support spring 5 supported by a support member 14 </ b> A fixed to the casing 15. The displacer 2 is also elastically fixed to the casing 15 by a displacer support spring 6 supported by the support member 14B.
Here, the internal space formed by the cylinder 3 is divided into a working space 7 and a back space 8 by the piston 1, and the working space 7 and the back space 8 are filled with a working medium such as helium gas in a high pressure state. .

  Further, the Stirling refrigerator 100A is provided with a linear motor 16, and the linear motor 16 is disposed with a predetermined gap with respect to the inner yoke 13 fixed to the cylinder 3 side and the inner yoke 13, and the bobbin / coil 9a. Is provided with an outer yoke main body 9 including an outer yoke 9b and a permanent magnet 12 attached to the piston 1 and disposed in a gap between the inner yoke 13 and the outer yoke 9b. The outer yoke 9b is fixed to the casing 15 side by positioning blocks 10a and 10b supported by the support member 14A.

The piston 1 reciprocates in the axial direction at a predetermined cycle by the action of the linear motor 16. By the reciprocating motion of the piston 1, the working medium is repeatedly compressed and expanded in the working space 7. The displacer 2 reciprocates linearly by a change in pressure of the working medium compressed and expanded in the working space 7.
The working space 7 is further divided into a compression space 7 a and an expansion space 7 b by the displacer 2, and the compression space 7 a and the expansion space 7 b are connected via the regenerator 4. Then, cold is generated in the cold head 3c at the tip of the cylinder 3 by the working medium in the expansion space 7b.

Also, for example, in Patent Document 2, the sliding and contact between the piston and the cylinder is reduced by flowing the compressed gas at the time of driving into the piston or the cylinder and ejecting it into the gap between the piston and the cylinder. Is disclosed.
For example, Patent Document 3 discloses a method of reducing sliding and contact between a piston and a cylinder by using a magnetic bearing system in which a piston shaft is formed of a soft magnetic material and is attracted by an electromagnet. Has been.
Japanese Patent No. 356647 Japanese National Patent Publication No. 9-510534 Japanese Patent Laid-Open No. 7-4763

  However, in the Stirling refrigerator of FIG. 6, the piston 1 is configured to slide with the cylinder 3 only by being supported by the piston support spring 5. For this reason, the clearance between the piston 1 and the cylinder 3 is increased due to the friction of the piston 1 and the cooling performance is reduced, or friction powder is caught between the piston 1 and the cylinder 3 to make the driving impossible. There was a problem to do.

  Further, the method disclosed in Patent Document 2 requires a special process for the piston and the cylinder, resulting in a complicated part and an increase in the number of parts, resulting in an increase in cost. In addition, in order to reduce the sliding and contact between the piston and the cylinder, the pressure difference at the time of compression of the piston is used, so the piston and the cylinder cannot be made completely non-contact, There was a limit to the life of pistons and cylinders.

Further, the method disclosed in Patent Document 3 has a problem that adjustment of the position of the piston and the cylinder in the axial direction is a main purpose, and adjustment of the position of the radial direction between the piston and the cylinder is not considered. Further, since the piston shaft is sucked, the length in the axial direction has to be secured, and there is a problem that the vibration type compressor is increased in size.
Furthermore, a method of increasing the radial rigidity of the support spring itself that supports the piston to reduce the contact between the piston and the cylinder is also conceivable, but this method increases the stress generated in the support spring when the piston is displaced. However, there is a problem that the reliability of the vibration type compressor is lowered.
Therefore, an object of the present invention is to provide a vibration type compressor that can reduce contact between a piston and a cylinder with a simple configuration without providing a mechanical support.

  In order to solve the above-described problem, according to the vibration type compressor according to claim 1, an inner yoke is provided, a piston capable of reciprocating in the axial direction, a cylinder for housing the piston, and the piston in the axial direction. A linear motor that is driven by a motor, and a casing that constitutes a pressure vessel in which the piston, cylinder, and linear motor are housed and in which a working gas is sealed, and the linear motor is a permanent magnet that is provided integrally with the piston. And a drive coil that is wound around the outer periphery of the permanent magnet, drives the piston in the axial direction, and is supported by the casing, and is radially divided so as to contain the drive coil. And a support coil that is wound independently for each outer yoke and controls the position of the piston in the radial direction. That.

  As a result, it is possible to control the position of the piston in the radial direction by passing an electric current through the support coil, and to support the piston in the casing while keeping the piston and the cylinder in a non-contact state. Become. This eliminates the need for a mechanical spring to support the piston and allows the piston to reciprocate in the axial direction without causing friction between the piston and the cylinder. The life of the vibration type compressor can be improved without degrading the performance.

Further, according to the vibration type compressor according to claim 2, the inner yoke is provided, the piston is reciprocable in the axial direction, the linear motor that drives the piston in the axial direction, and the pressure vessel in which the working gas is sealed. The linear motor is disposed on the outer side of the casing and covers the outer periphery of the permanent magnet. The casing also serves as a cylinder for the piston. Winding coil, outer yoke radially divided so as to contain the driving coil, and each outer yoke is wound independently, and the position of the piston is set in the radial direction. And a supporting coil to be controlled.
Thereby, it is not necessary to accommodate the stator of the linear motor inside the casing, and the stator of the linear motor can be separated from the working gas. For this reason, it becomes possible to reduce the contamination source of working gas, to suppress the deterioration of cooling performance, and to improve the reliability of the vibration type compressor.

  According to the vibration type compressor according to claim 3, a piston capable of reciprocating in the axial direction, a linear motor for driving the piston in the axial direction, and a pressure in which the linear motor is accommodated and in which working gas is sealed The linear motor includes an inner yoke connected to the piston, and a permanent magnet integrally provided on the inner yoke. The casing includes a casing that forms a container, and a cylinder that is connected to the casing and accommodates the piston. And a driving coil wound so as to cover the outer periphery of the permanent magnet, and an outer yoke supported by the cylinder or casing and radially divided so as to contain the driving coil, Each of the outer yokes is wound independently and includes a supporting coil that controls the position of the piston in the radial direction.

  As a result, the piston can be separated from the thrust generating portion, and the gap between the inner yoke and the outer yoke can be reduced by disposing the cylinder between the inner yoke and the outer yoke. . For this reason, it is possible to reduce the magnetic resistance of the magnetic circuit formed between the inner yoke and the outer yoke, and it is possible to reduce the supply current to the driving coil necessary for generating the same thrust.

According to a fourth aspect of the present invention, the piston is formed of a cylindrical or donut-shaped movable magnet.
As a result, the position of the piston can be controlled in the radial direction while reducing the number of parts, and the length in the axial direction can be shortened, and the vibration type compressor can be made compact and inexpensive. While realizing this, it is possible to extend the life of the vibration type compressor.

According to a fifth aspect of the present invention, the permanent magnet includes a main magnet and a side magnet that are magnetized so that radial magnetic poles are different from each other.
Thereby, by displacing the piston to the left or right, a suction force can be applied toward the outer yoke, and a restoring force to the neutral position can always be applied. For this reason, by adjusting the restoring force, the gas spring force of the working gas, and the inertial force of the movable part, it is possible to realize the resonance of the axial movement of the piston. The length in the axial direction can be shortened as unnecessary.

In addition, according to the vibration type compressor of the sixth aspect, the current is passed through any one of the support coils and is smaller than the support coil adjacent to the support coil in the circumferential direction. The position of the piston is controlled in the radial direction by flowing an electric current in the reverse direction.
As a result, when controlling the piston position in the radial direction, it is possible to prevent variations in thrust in the radial direction of the piston and to prevent the piston from tilting and to stabilize the piston in the neutral position in the radial direction. And can be held.

  As described above, according to the present invention, by providing a support coil that controls the position of the piston in the radial direction, the piston can be supported in the casing while keeping the piston and the cylinder in a non-contact state. It becomes possible. This eliminates the need for a mechanical spring to support the piston and allows the piston to reciprocate in the axial direction without causing friction between the piston and the cylinder. The life of the vibration type compressor can be improved without degrading the performance.

Hereinafter, a vibration type compressor according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1A is a cross-sectional view showing a schematic configuration of the vibration type compressor according to the first embodiment of the present invention, and FIG. 1B is a diagram of the vibration type compressor according to the first embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view showing a part of the vibration type compressor of FIG. 1.

  1 and 2, the vibration type compressor is provided with a pair of opposed movable vibration type pistons 102, a cylinder 103 that accommodates the pistons 102, and a pair of linear motors that drive the pistons 102 in the axial direction. The piston 102, the cylinder 103, and the linear motor are accommodated in the casing 101. Note that helium gas of about several MPa is sealed inside the vibration type compressor, and the casing 101 can constitute a pressure vessel. In addition, a cylinder 103 is disposed outside the piston 102 through a minute gap in the radial direction. In consideration of some sliding when the piston 102 is inserted, at least one of the piston 12 and the cylinder 103 is disposed. The surface may be coated with a solid lubricant.

  Here, the linear motor is provided with a stator fixed inside the casing 101 and a mover fixed to the piston 102. The mover is provided with a main magnet 102b provided integrally with the piston 102 and a pair of side magnets 102c arranged on both sides thereof. The piston 102 is provided with an inner yoke 102a, and the main magnet 102b and the side magnet 102c can constitute the piston 102 together with the inner yoke 102a. Here, the inner yoke 102a can be formed in a cylindrical shape with a soft magnetic material such as iron. Further, the main magnet 102b and the side magnets 102c may be constituted by outer peripheral single pole ring-shaped magnets, or may be constituted by arranging outer peripheral single pole segment type magnets in the circumferential direction. Further, the main magnet 102b and the side magnet 102c can be magnetized so that the magnetic poles in the radial direction are different from each other. The piston 102 may be constituted by a cylindrical or donut-shaped movable magnet.

  On the other hand, the stator of the linear motor is wound so as to cover the outer periphery of the main magnet 102 b, and the drive coil 106 that drives the piston 102 in the axial direction and the radial direction radially so as to include the drive coil 106. Each of the divided outer yoke 104 and the outer yoke 104 is provided with a supporting coil 107 that is wound independently and controls the position of the piston 102 in the radial direction. The driving coil 106 is supported by the casing 101 via the support member 105. The outer yoke 104 can be configured by a block in which silicon steel plates or the like are stacked in multiple layers. For example, the outer yoke 104 can be divided into eight parts in the circumferential direction. The driving coil 106 is connected to an AC power source, and the supporting coil 107 is connected to a DC power source independently.

On the cylinder 103, at least four position detectors 108 for detecting a gap between the piston 102 and the cylinder 103 are arranged in the circumferential direction.
For example, when a current is passed clockwise through the driving coil 106, the magnetic flux flows from the right to the left through the inner yoke 102a, and the interaction between the magnetic flux generated between the gap with the outer yoke 104 and the magnetic flux generated by the main magnet 102b. As a result, thrust is generated in the left direction, and the right piston 102 can be moved in the left direction. Further, by making the current flowing through the driving coil 106 reverse, a thrust is generated in the reverse direction, and the piston 102 can be moved in the reverse direction. For this reason, the piston 102 can be reciprocated by supplying an alternating current such as a sine wave to the driving coil 106.

  Further, the position detector 108 can detect which side of the piston 102 is in the radial direction, and the current flowing through the support coil 107 can be controlled based on the detection result. Then, by controlling the current flowing through the support coil 107, the suction force acting on the inner yoke 102a is adjusted, and a gap is secured between the piston 102 and the cylinder 103, while the piston 102 and the cylinder 103 are not in contact with each other. Can be kept in a state.

  As a result, it is possible to control the position of the piston 102 in the radial direction by passing an electric current through the support coil 107, and the piston 102 is moved in the casing 101 while keeping the piston 102 and the cylinder 103 in a non-contact state. It becomes possible to support. This eliminates the need for a mechanical spring for supporting the piston 102 and allows the piston 102 to reciprocate in the axial direction without causing friction between the piston 102 and the cylinder 103. The life of the vibration type compressor can be improved without deteriorating the cooling performance of the compressor.

  Further, by arranging the side magnets 102c on both sides of the main magnet 102b, when the piston 102 is displaced to the left or right, an attractive force can be exerted toward the outer yoke 104, and the restoring force to the neutral position is always obtained. Can work. Therefore, by adjusting the restoring force, the gas spring force of the working gas, and the inertial force of the movable part, it is possible to realize the resonance of the axial movement of the piston 102, such as a mechanical disk-like spring. The length in the axial direction can be shortened.

  In the above-described embodiment, the method of providing the position detector 108 for detecting the radial position of the piston 102 has been described. However, the position detector 108 is not necessarily provided, and the current waveform of the driving coil 106 is not necessarily provided. The current flowing through the support coil 107 may be adjusted while confirming the behavior of the piston 102 by monitoring the above.

FIG. 3 is a cross-sectional view showing a schematic configuration of a vibration type compressor according to a second embodiment of the present invention.
In FIG. 3, the vibration type compressor is provided with a pair of opposed movable vibration type pistons 202 and a pair of linear motors that drive the pistons 202 in the axial direction. Are accommodated in a casing 201 configured to also serve as a cylinder. In addition, helium gas of about several MPa is sealed inside the vibration type compressor, and the casing 201 can constitute a pressure vessel.

  Here, the linear motor is provided with a stator fixed to the outside of the casing 201 and a mover fixed to the piston 202. The mover is provided with a main magnet 202b provided integrally with the piston 202 and a pair of side magnets 202c arranged on both sides thereof. The piston 202 is provided with an inner yoke 202a, and the main magnet 202b and the side magnet 202c can constitute the piston 202 together with the inner yoke 202a. Here, the inner yoke 202a can be formed in a cylindrical shape with a soft magnetic material such as iron. Further, the main magnet 202b and the side magnet 202c may be configured by outer peripheral single pole ring-shaped magnets, or may be configured by arranging outer peripheral single pole segment type magnets in the circumferential direction. Further, the main magnet 202b and the side magnet 202c can be magnetized so that the magnetic poles in the radial direction are different from each other. The piston 202 may be configured by a cylindrical or donut-shaped movable magnet.

  On the other hand, the stator of the linear motor is wound so as to cover the outer periphery of the main magnet 202b, and the driving coil 206 for driving the piston 202 in the axial direction and the driving coil 206 are radially included in the circumferential direction. Each of the divided outer yoke 204 and the outer yoke 204 is provided with a supporting coil 207 that is wound independently and controls the position of the piston 202 in the radial direction. The drive coil 206 is supported by the casing 201 via the support member 205.

Then, by controlling the current flowing through the support coil 207, the suction force acting on the inner yoke 202a is adjusted, and a gap is secured between the piston 202 and the cylinder 203, while the piston 202 and the cylinder 203 are not in contact with each other. Can be kept in a state. Further, by passing an alternating current through the driving coil 206, a thrust is generated in the axial direction by the interaction between the magnetic flux generated between the gap with the outer yoke 204 and the magnetic flux by the main magnet 202b, and the piston 202 is reciprocated. be able to.
Thereby, it is not necessary to house the stator of the linear motor inside the casing 201, and the stator of the linear motor can be separated from the working gas. For this reason, it becomes possible to reduce the contamination source of working gas, to suppress the deterioration of cooling performance, and to improve the reliability of the vibration type compressor.

FIG. 4 is a cross-sectional view showing a schematic configuration of a vibration type compressor according to a third embodiment of the present invention.
In FIG. 4, the vibration type compressor accommodates a pair of opposed movable vibration type pistons 302, a cylinder 303 that accommodates the pistons 302, a pair of linear motors that drive the pistons 302 in the axial direction, and linear motors. A casing 301 connected to the cylinder 303 is provided. In addition, helium gas of about several MPa is sealed inside the vibration type compressor, and the casing 301 and the cylinder 303 can constitute a pressure vessel.

  Here, the linear motor is provided with a stator fixed inside the casing 301 and a mover that can move integrally with the piston 302. The mover is provided with an inner yoke 302a connected to the piston 302, a main magnet 302b provided integrally with the inner yoke 302a, and a pair of side magnets 302c disposed on both sides thereof. Here, the inner yoke 302a can be formed in a cylindrical shape with a soft magnetic material such as iron. Further, the main magnet 302b and the side magnet 302c may be configured by an outer peripheral single pole ring-shaped magnet, or may be configured by arranging outer peripheral single pole segment type magnets in the circumferential direction. The main magnet 302b and the side magnet 302c can be magnetized so that the magnetic poles in the radial direction are different from each other.

  On the other hand, the stator of the linear motor is wound so as to cover the outer periphery of the main magnet 302b, and the drive coil 306 that drives the piston 302 in the axial direction and the drive coil 306 are radially included in the circumferential direction. Each of the divided outer yoke 304 and the outer yoke 304 is provided with a supporting coil 307 that is independently wound and controls the position of the piston 302 in the radial direction. The drive coil 306 is supported by the cylinder 303 via the support member 305.

  Then, by controlling the current flowing through the support coil 307, the suction force acting on the inner yoke 302a is adjusted, and a gap is secured between the piston 302 and the cylinder 303 while the piston 302 and the cylinder 303 are not in contact with each other. Can be kept in a state. Further, by passing an alternating current through the driving coil 306, a thrust is generated in the axial direction by the interaction between the magnetic flux generated between the gap with the outer yoke 304 and the magnetic flux by the main magnet 302b, and the piston 302 is reciprocated. be able to.

  As a result, the thrust generating portion of the piston 302 can be separated from the piston 302, and the cylinder 303 is not disposed between the inner yoke 302a and the outer yoke 304, so that the portion between the inner yoke 302a and the outer yoke 304 is not disposed. The gap can be reduced. For this reason, the magnetic resistance of the magnetic circuit formed between the inner yoke 302a and the outer yoke 304 can be reduced, and the supply current to the driving coil 306 required to generate the same thrust can be reduced. Can do.

FIG. 5 is a longitudinal sectional view showing a schematic configuration of a vibration type compressor according to a fourth embodiment of the present invention.
In FIG. 5, it is assumed that the supporting coil 107 in FIG. 1 includes eight driving coils 107a to 108h that are divided from each other. For example, when the position of the piston 102 is corrected upward, the current Ia is supplied to the support coil 107a, and the current Ib smaller than the support coils 107b and 107h circumferentially adjacent to the support coil 107a. , Ih is allowed to flow in the opposite direction, whereby the position of the piston 102 can be controlled in the radial direction.

Accordingly, when the position of the piston 102 is controlled in the radial direction, it is possible to prevent a variation in thrust in the radial direction of the piston 102, and to prevent the piston 102 from being tilted to a neutral position in the radial direction. The piston can be held.
In the above-described embodiment, the method of forming the inner yoke in a cylindrical shape has been described. However, the inner yoke of the portion facing the side opposite to the compression space side has a shape that is hollowed out so as not to be magnetically saturated. Alternatively, it may have a movable cylinder shape in which the compression space side is hollowed out. In the above-described embodiment, the method of dividing the outer yoke into eight has been described. However, the outer yoke may be divided into six, may be divided into twelve, or may be divided into other numbers.

FIG. 1A is a cross-sectional view showing a schematic configuration of the vibration type compressor according to the first embodiment of the present invention, and FIG. 1B is a diagram of the vibration type compressor according to the first embodiment of the present invention. It is a longitudinal cross-sectional view which shows schematic structure. It is a cross-sectional view which expands and shows a part of vibration type compressor of FIG. It is a cross-sectional view which shows schematic structure of the vibration type compressor which concerns on 2nd Embodiment of this invention. It is a cross-sectional view which shows schematic structure of the vibration type compressor which concerns on 3rd Embodiment of this invention. It is a longitudinal cross-sectional view which shows schematic structure of the vibration type compressor which concerns on 4th Embodiment of this invention. It is a cross-sectional view which shows schematic structure of the conventional vibration type compressor.

Explanation of symbols

101, 201, 301 Casing 102, 202, 302 Piston 102a, 202a, 302a Inner yoke 102b, 202b, 302b Main magnet 102c, 202c, 302c Side magnet 103, 303 Cylinder 104, 204, 304 Outer yoke 105, 205, 305 Support Member 106, 206, 306 Driving coil 107, 207, 307, 407a to 407h Supporting coil 108 Position detector

Claims (6)

A piston provided with an inner yoke and capable of reciprocating in the axial direction;
A cylinder containing the piston;
A linear motor for driving the piston in the axial direction;
A casing that houses the piston, cylinder, and linear motor, and that constitutes a pressure vessel filled with working gas;
The linear motor is
A permanent magnet provided integrally with the piston;
A drive coil wound around the outer periphery of the permanent magnet and driving the piston in the axial direction;
An outer yoke supported by the casing and radially divided in a circumferential direction so as to enclose the driving coil;
A vibration type compressor comprising: a support coil that is wound independently for each outer yoke and that controls a position of the piston in a radial direction. A piston provided with an inner yoke and capable of reciprocating in the axial direction;
A linear motor for driving the piston in the axial direction;
A pressure vessel filled with a working gas, and a casing that also serves as a cylinder for the piston; and
The linear motor is
A permanent magnet provided integrally with the piston;
A driving coil disposed outside the casing and wound around the outer periphery of the permanent magnet;
An outer yoke radially divided in a circumferential direction so as to enclose the driving coil;
A vibration type compressor comprising: a support coil that is wound independently for each outer yoke and that controls a position of the piston in a radial direction. A piston capable of reciprocating in the axial direction;
A linear motor for driving the piston in the axial direction;
A casing constituting a pressure vessel in which the linear motor is housed and in which a working gas is enclosed;
A cylinder connected to the casing and containing the piston;
The linear motor is
An inner yoke coupled to the piston;
A permanent magnet provided integrally with the inner yoke;
A drive coil wound so as to cover the outer periphery of the permanent magnet;
An outer yoke supported by the cylinder or casing and radially divided in a circumferential direction so as to contain the driving coil;
A vibration type compressor comprising: a support coil that is wound independently for each outer yoke and that controls a position of the piston in a radial direction.   The vibration type compressor according to any one of claims 1 to 3, wherein the piston is configured by a cylindrical or donut-shaped movable magnet.   5. The vibration type compressor according to claim 1, wherein the permanent magnet includes a main magnet and a side magnet which are magnetized so that magnetic poles in a radial direction are different from each other.   A current is passed through any one of the supporting coils, and a smaller current is passed in the opposite direction to the supporting coil adjacent to the supporting coil in the circumferential direction, thereby reducing the position of the piston. 6. The vibration type compressor according to claim 1, wherein the vibration type compressor is controlled in a direction.

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