JP2009065755A - Vibrating-type motor and vibrating-type compressor using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vibrating-type motor capable of achieving low cost and high reliability by simplifying a design parameter and improving motor efficiently without reducing thrust force increase effects by an auxiliary magnet, and to provide a movable magnet-type compressor using the same. <P>SOLUTION: The vibrating-type motor is provided with: a movable portion having a substantially cylindrical main magnet made of a permanent magnet having inner and outer peripheral sides magnetized on different poles, and substantially cylindrical auxiliary magnets each coaxially joined to both axial end portions of the main magnet and made of a permanent magnet having inner and outer peripheral sides magnetized on the magnetism reverse to those of the main magnet; a plurality of exciting yokes having two leg portions opposite to the movable portion via a predetermined gap portion on the radius direction outside of the movable portion and equally disposed in the circumferential direction of the movable portion; exciting coils individually wound on each of the plurality of exciting yokes and generating a magnetic flux to the leg portions; and a cylindrical back yoke disposed to be opposite to the exciting yokes on the diameter direction inside of the movable portion. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vibration type motor that can be used for a vibration type compressor of a Stirling refrigerator, and a vibration type compressor using the vibration type motor.

Conventionally, a movable magnet type linear motor (hereinafter also simply referred to as a movable magnet type motor) has been used as this type of vibration type motor.
FIG. 5 and FIG. 6 are schematic configuration diagrams for explaining the driving principle of the movable magnet type motor, and all show a part of a sectional view along the central axis C of the substantially cylindrical motor. .
In FIG. 5, 101 is an exciting yoke, 102 is an exciting coil, 103 is a back yoke, 104 is disposed in a gap between the exciting yoke 101 and the back yoke 103, and the inner and outer peripheral sides are magnetized to have different polarities. The movable part 201 made of a cylindrical permanent magnet is a magnetic flux generated by the movable part 104. The casing that supports the movable portion 104 is not shown.
In many movable magnet type motors, a single permanent magnet magnetized as the movable part 104 is used as shown in the figure, and this movable part 104 is integrally connected to a piston (not shown). In addition, both end portions in the axial direction of the movable portion 104 are accommodated within the leg width of the excitation yoke 101.
As shown in FIG. 5, when the outer peripheral side of the movable part 104 is an N pole and the inner peripheral side is an S pole, the magnetic flux 201 generated from the outer peripheral side goes around the outer side of the movable part 104 and returns to the inner peripheral side. For this reason, at both ends in the axial direction of the movable portion 104, the magnetic flux 201 is equivalent to the magnetic flux generated when current flows in the opposite direction in the direction perpendicular to the paper surface. This is called the equivalent current I _M of the permanent magnet.

As shown in FIG. 6, when a magnetic flux B is generated by applying an alternating current to the exciting coil 102 and this magnetic flux B is linked to the gap G where the equivalent current I _M exists, the movable part disposed in the gap G In accordance with Fleming's left-hand rule, 104 reciprocates in response to a horizontal force (thrust) in the figure.
The thrust F can be simply calculated by Equation 1.

ここで、Ｂは空隙部Ｇの磁束密度、Ｌ_Mは可動部１０４の周方向の平均長さである。
数式１において、通常のＢ・Ｉ・Ｌ則と異なって等価電流Ｉ_Mが２倍されているのは、本モデルでは可動部１０４の軸方向両端部の２箇所に等価電流Ｉ_Mが存在するためである。
一方、可動部１０４は、図示していない軸方向に適正なばね力を持つ機械ばね（例えば、コイルばねや板ばね）を設置している（特許文献２参照）。これは、機械振動の共振点で運転させることで、入力電力を抑えることができるからである。一般的には、スターリング冷凍機では、40〜80Hzの比較的低周波数で運転される。
また、図５，図６に示すように、励磁ヨーク１０１が励磁コイル１０２を覆うように配置するには、励磁ヨーク１０１を分割可能な構造とし、励磁ヨーク１０１と励磁コイル１０２を別個に製造した後に組み合わせて整合する必要がある。具体的には、励磁ヨーク１０１を、円筒周方向に分割された構造（特許文献２参照）や、円筒軸方向に脚部１１１，１１２が分割可能な構造とし、後に組み合わせて整合することが多い。

Here, B is the magnetic flux density of the gap G, and L _M is the average length in the circumferential direction of the movable portion 104.
In Equation 1, the equivalent current I _M is doubled unlike the normal B · I · L rule. In this model, the equivalent current I _M exists at two positions on both ends of the movable portion 104 in the axial direction. Because.
On the other hand, the movable part 104 is provided with a mechanical spring (for example, a coil spring or a leaf spring) having an appropriate spring force in the axial direction (not shown) (see Patent Document 2). This is because the input power can be suppressed by operating at the resonance point of mechanical vibration. Generally, a Stirling refrigerator is operated at a relatively low frequency of 40 to 80 Hz.
Also, as shown in FIGS. 5 and 6, in order to arrange the excitation yoke 101 so as to cover the excitation coil 102, the excitation yoke 101 has a structure that can be divided, and the excitation yoke 101 and the excitation coil 102 are manufactured separately. It is necessary to combine and match later. Specifically, the excitation yoke 101 has a structure divided in the cylindrical circumferential direction (see Patent Document 2) or a structure in which the leg portions 111 and 112 can be divided in the cylindrical axis direction, and is often combined and matched later. .

By the way, in order to increase the thrust F without changing the physique of the motor (L _M = constant), it is sufficient to increase the magnetic flux density B or the equivalent current I _M in the air gap as is apparent from Equation 1. .
First, in order to increase the magnetic flux density B, it is necessary to shorten the gap length of the gap or increase the exciting current flowing through the exciting coil 102. However, in the former method, the movable part 104 and the member supporting it are thinned, so that the strength is insufficient and the processing cost is likely to increase. The latter method increases Joule heat loss (I ² R) and decreases performance. There is a problem of inviting.
On the other hand, in order to increase the equivalent current I _M , it is conceivable to use a permanent magnet having a larger magnetic force in addition to changing the thickness of the permanent magnet as the movable portion 104. However, both of them cause an increase in cost.
Therefore, as another method for increasing the thrust F, a structure as shown in FIG. 7 can be considered. In this movable magnet type motor, cylindrical auxiliary magnets 106 and 107 magnetized in the opposite direction to the main magnet 105 are coaxially and integrally joined to both ends of the cylindrical main magnet 105 in the axial direction. The movable portion 104A is formed, and the equivalent current I _M is virtually increased.
According to the structure of FIG. 7, the neutral position of the movable portion 104 </ b> A compared to the structures of FIGS. 5 and 6 by canceling out the magnetic flux at the joint between the main magnet 105 and the auxiliary magnets 106 and 107 in the non-excited state. There is also an advantage that the holding force in the is increased and so-called automatic neutral positioning (self-centering) is facilitated.

As shown in FIG. 7, a movable magnet type motor described in Patent Document 1 is known as a conventional technique including a movable portion including a main magnet and a pair of auxiliary magnets.
FIG. 8 is a configuration diagram of the movable magnet type motor described in Patent Document 1. In FIG. In FIG. 8, 201 is a back yoke, 202 is an exciting coil, 203 is an exciting yoke, 204 is a movable part, 205 is a main magnet, 206 and 207 are auxiliary magnets, 300 is a Stirling engine, 301 is a casing, 302 is a piston, 303 Is a display server. Reference numeral 210 denotes a neutral position of the movable unit 204.
US Pat. No. 5,148,066 (FIG. 1) Japanese Patent Laid-Open No. 2005-9397

In the prior art, when the movable part 104 shown in FIGS. 5 and 6 is a single permanent magnet, the magnetic flux passing through the excitation yoke 101 increases as the displacement of the magnet increases, and the interlinkage magnetic flux of the excitation coil 102 increases. Changes significantly.
When the movable portion 104A shown in FIG. 7 uses the main magnet 105 and the auxiliary magnets 106 and 107, most of the magnetic flux loops only in the leg portions 111 and 112 in the excitation yoke 101. Almost no change in magnetic flux. However, since the exciting coil 102 wound in a substantially cylindrical shape is used, the interlinkage magnetic flux of the exciting coil 102 changes when the movable portion 104A made of a permanent magnet moves along the cylindrical axis of the exciting coil 102.
In either case, an electromotive force is generated because the interlinkage magnetic flux of the exciting coil 102 changes, and this electromotive force must be taken into consideration when designing electrical resonance, making the design difficult.
Further, the excitation yoke 101 has a structure that can be divided, and the excitation yoke 101 and the excitation coil 102 are combined and matched, so that the cost is high. Further, since the exciting yoke 101 covers the exciting coil 102, there is a problem that the heat radiation environment of the exciting coil 102 is bad and the efficiency of the entire motor is lowered.

On the other hand, when the exciting yoke 101 is radially arranged radially outside the exciting coil 102, all of the plural exciting yokes are excited by the single exciting coil 102, so that the coil impedance is increased. As a result, the power factor of the motor deteriorated, increasing the burden on the power supply.
Therefore, the problem to be solved by the present invention is to use a vibration type motor that simplifies design parameters, increases the efficiency of the motor, realizes low cost, and achieves high reliability without reducing the effect of increasing thrust by the auxiliary magnet. The object is to provide a movable magnet compressor.

In order to solve the above problem, the invention according to claim 1
A substantially cylindrical main magnet composed of permanent magnets magnetized with different polarities on the inner peripheral side and the outer peripheral side, and the axially opposite ends of the main magnet are respectively joined coaxially, and the inner peripheral side and the outer peripheral side are A movable part having a substantially cylindrical auxiliary magnet made of a permanent magnet magnetized with a polarity opposite to that of the main magnet;
A plurality of exciting yokes provided with two legs opposed to the movable part through a constant gap on the radially outer side of the movable part in the previous period, and arranged evenly in the circumferential direction of the movable part;
An exciting coil that is individually wound around the plurality of exciting yokes and generates magnetic flux in the legs;
A cylindrical back yoke disposed on the radially inner side of the movable part so as to face the excitation yoke,
An alternating current is passed through the exciting coil to reciprocate the movable part in the axial direction.
According to a second aspect of the present invention, in the vibration type motor according to the first aspect, the excitation yoke is integrally formed without being divided in the magnetic flux direction.
According to a third aspect of the present invention, in the vibration type motor according to the first or second aspect, the excitation yoke is formed by laminating electromagnetic steel sheets and crimping.

According to a fourth aspect of the present invention, in the vibration type motor according to any one of the first to third aspects, the axial length of the movable portion is outside the surface closest to the previous movable portion in the excitation yoke leg portion. It is characterized by being longer than the distance between the end portions.
The invention according to claim 5 is a vibration type compressor equipped with the vibration type motor according to any one of claims 1 to 4, further comprising a pressure casing that maintains airtightness with the outside, and inside the pressure casing, The inner wall of the pressure casing and the exciting coil are in contact with each other.
According to a sixth aspect of the present invention, in the vibration type compressor mounted with the vibration type motor according to any one of the first to fourth aspects, the exciting coil is molded so as to be integrated with a good heat conductive material, and the pressure is increased. Inside the casing, the inner wall of the pressure casing and the molded part are in contact with each other.

  ADVANTAGE OF THE INVENTION According to this invention, without reducing the thrust increase effect by an auxiliary magnet, the design parameter is simplified, the efficiency of the motor is increased, and the vibration type motor that realizes low cost and high reliability, and the movable magnet type using the same It is possible to provide a compressor.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a main part of an embodiment of a vibration type motor according to the present invention, and is a cross-sectional view along a motor central axis C. 2 is a cross-sectional view taken along the line AA shown in FIG.
In FIG. 1 or FIG. 2, 1 is an excitation yoke, 2 is an excitation coil individually wound around the excitation yoke 1, 3 is a back yoke, and 4 is a cylinder disposed in the gap between the excitation yoke 1 and the back yoke 3. It is a movable part which consists of a permanent magnet.
The movable portion 4 is a cylindrical auxiliary magnet magnetized in the opposite direction to the main magnet 5 at both ends in the axial direction of the cylindrical main magnet 5 magnetized with the N pole on the outer peripheral side and the S pole on the inner peripheral side. Magnets 6 and 7 are coaxially and integrally connected. The main magnet 5 and the auxiliary magnets 6 and 7 are fixed to the magnet holder 10. In addition, 8 and 9 are joint parts of the main magnet 5 and the auxiliary magnets 6 and 7.
For the main magnet 5 and the auxiliary magnets 6 and 7, rare earth permanent magnets such as neodymium and samarium are used.
As shown in FIG. 2, the plurality of exciting yokes 1 in which the exciting coils 2 are individually wound are based on the inner diameters of the two leg portions 11 and 12 that generate magnetic fluxes on the radially outer side of the cylindrical movable portion 4. Are arranged radially.

The excitation yoke 1 is integrally formed without being divided in the magnetic flux direction. This is because the magnetic resistance of the excitation yoke 1 is reduced and the motor efficiency is improved as compared with the case where the magnetic flux is divided in the magnetic flux direction. Further, the coaxiality of the inner diameters of the leg portions 11 and 12 is determined by the processing accuracy, and it becomes easy to configure a uniform clearance with the back yoke. As a result, variations in product performance can be suppressed, and at the same time, design tolerances can be relaxed, and costs can be reduced.
The exciting yoke 1 is preferably formed by laminating a plurality of iron plates, silicon steel plates and the like. This is because when an alternating magnetic field is applied like a vibration type motor, by insulating the direction perpendicular to the magnetic flux, eddy currents generated in the excitation yoke 1 can be suppressed and performance degradation can be prevented.
In addition, when laminating | stacking and forming the excitation yoke 1, it is preferable to crimp-bond the laminated steel plate etc. which carried out the press work. This is because the winding of the exciting coil 2 can be performed as it is by making the blocks by laminating steel plates for lamination and the like into blocks. Further, since the laminated steel plates are fixed by the exciting coil 2 and do not spread, post-processing such as welding can be eliminated, and the cost can be reduced.
The lengths of the auxiliary magnets 6 and 7 along the axial direction are such that both end portions of the movable portion 4 (one end of each of the auxiliary magnets 6 and 7) are in contact with the leg portions 11 and 12 even at the maximum displacement required as a motor stroke. Thus, the length does not reach the surface closest to the movable portion 4. This is because, when the lengths of the auxiliary magnets 6 and 7 are short, a reaction force due to an equivalent current (see FIG. 8) existing at the outer ends of the auxiliary magnets 6 and 7 is generated. This is because it becomes smaller.

The support springs 13 and 14 are fastened to the excitation yoke 1 via ring-shaped spacers 15 and 16. The spacers 15 and 16 are made of a nonmagnetic material (for example, stainless steel). Further, both end portions of the magnet holder 10 are fastened to the support springs 13 and 14.
As the support springs 13 and 14, for example, a flexure bearing formed by laminating a plurality of spiral-shaped slits on a disk is generally used. This is because this type of spring has a great rigidity in the radial direction and can be strongly supported, but has a small rigidity in the axial direction and can vibrate freely.
As a result, the exciting yoke 1 is fixed, and an alternating current having the same phase is passed through the plurality of exciting coils 2, whereby a thrust acts on the main magnet 5 and the auxiliary magnets 6 and 7, and the magnet holder in which the movable part 4 is fixed. 10 will move left and right.
Since the excitation coils 2 are individually wound around the plurality of excitation yokes 1 and are arranged radially outside the cylindrical movable part 4, the permanent magnets do not move inside the excitation coil 2. The exciting coil 2 generates almost no electromotive force, and the design considering dynamic characteristics becomes easy.
Further, by exciting the divided excitation yokes 1 with individual excitation coils 2, a circuit in which the inductance components of the coils are arranged in parallel is obtained, and the power factor can be improved by reducing the inductance components. .

Next, FIG. 3 is a block diagram showing one embodiment of a compressor using a vibration type motor. In the compressor shown in FIG. 3, a pressure casing 22 is installed so as to cover the vibration type motor 21 described above. The exciting coil 2 of the vibration type motor according to the present invention exists in the maximum outer diameter portion of the motor. Therefore, the exciting coil 2 and the pressure casing 22 can be configured to contact each other. A specific contact method can be realized by a method of increasing the contact pressure such as press fitting or shrink fitting.
With this configuration, heat generated by the exciting coil 2 can be directly conducted to the pressure casing 22 having a large surface area, and not only the vibration type motor 21 can be protected but also the motor efficiency can be improved.
Next, FIG. 4 is a block diagram showing another embodiment of a compressor using a vibration type motor.
As shown in FIG. 4, at least the excitation yoke 1 and the excitation coil 2 are included in order to increase the thermal conductivity from the vibration type motor 21 to the pressure casing 22 and at the same time improve the workability at the time of assembly of the vibration type motor 21. The outer periphery of the vibration type motor 21 is molded with a good heat conductive material 31 (for example, aluminum). By doing so, the contact surface between the pressure casing 22 and the vibration type motor is increased, heat dissipation can be further promoted, and the insulation reliability of the exciting coil 2 is improved.

  As in the second embodiment, the assembly is performed by a method having a large contact pressure such as press fitting or shrink fitting.

It is a block diagram which shows the embodiment of the vibration type motor which concerns on this invention. It is AA sectional drawing of the vibration type motor which concerns on this invention. It is a block diagram of the 1st embodiment of the compressor using the vibration type motor which concerns on this invention. It is a block diagram of the 2nd embodiment of the compressor using the vibration type motor which concerns on this invention. It is a block diagram for demonstrating the drive principle of a movable magnet type motor. It is a block diagram for demonstrating the drive principle of a movable magnet type motor. It is a block diagram for demonstrating a prior art. It is a block diagram which shows the prior art described in patent document 1.

Explanation of symbols

1: Excitation yoke 2: Excitation coil 3: Back yoke 4: Moving part 5: Main magnet 6, 7: Auxiliary magnet 8, 9: Joint part 10: Magnet holder 11, 12: Leg part 13, 14: Support spring 15, 16: Spacer

Claims (6)

A substantially cylindrical main magnet composed of permanent magnets magnetized with different polarities on the inner peripheral side and the outer peripheral side, and the axially opposite ends of the main magnet are respectively joined coaxially, and the inner peripheral side and the outer peripheral side are A movable part having a substantially cylindrical auxiliary magnet made of a permanent magnet magnetized with a polarity opposite to that of the main magnet;
A plurality of exciting yokes provided with two legs facing the movable part through a constant gap on the radially outer side of the movable part, and arranged uniformly in the circumferential direction of the movable part;
An exciting coil that is individually wound around the plurality of exciting yokes and generates magnetic flux in the legs;
A cylindrical back yoke disposed on the radially inner side of the movable part so as to face the excitation yoke,
An oscillation type motor characterized in that an alternating current is passed through the excitation coil to reciprocate the movable part in the axial direction.   2. The vibration type motor according to claim 1, wherein the excitation yoke is integrally formed without being divided in the magnetic flux direction.   3. The vibration type motor according to claim 1, wherein the excitation yoke is formed by laminating electromagnetic steel plates and crimping.   4. The axial length of the movable part is longer than the distance between the outer end portions of the surface of the excitation yoke leg that is closest to the previous movable part. The vibration type motor described in item 1.   5. The pressure casing according to claim 1, further comprising a pressure casing that maintains airtightness with the outside, wherein the inner wall of the pressure casing and the excitation coil are in contact with each other inside the pressure casing. A vibration type compressor equipped with the vibration type motor described in the section. The said exciting coil is molded so that it may become united with a good heat conductive material, and the inner wall of the said pressure casing and the said molding part are contacting in the inside of the said pressure casing. 5. A vibration type compressor equipped with the vibration type motor described in any one of items 4 above.

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