JP5334295B2 - Permanent magnet motor and hermetic compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a current capacity of a drive device by reducing a current required for magnetization. <P>SOLUTION: A permanent magnet motor 21 has two or more kinds of permanent magnets 33, 34, having different characteristics, inside a rotor 24. A current is made to flow in each stator winding 37 by a drive device. One permanent magnet 34 is magnetized and demagnetized by a magnetic field generated by each winding 37 so as to make a magnetic-flux amount variable, thereby operating the permanent magnet motor. The permanent magnets 33, 34 are configured, by using a rare-earth magnet; and the thickness of one permanent magnet 34, making the magnetic-flux amount variable by being magnetized and demagnetized, is set smaller than that of the other permanent magnet 33 so as to reduce the coercive force. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a permanent magnet motor and a hermetic compressor, and more particularly to a motor that can be operated with a variable amount of magnetic flux.

  In a permanent magnet motor used for a hermetic compressor, a stator that constitutes an armature by winding a coil around a stator core made of magnetic material, and a plurality of permanent magnets for main field on the peripheral surface of the rotor core made of magnetic material Are arranged at equal intervals, and two types of permanent magnets are provided between the main field and poles of the rotor (see, for example, Patent Document 1). For example, rare earth (NdFeB) is used as the permanent magnet of the main field, and alnico or FeCrCo is used as the magnet between the poles. In this permanent magnet motor, the field is weakened by the armature d-axis current during high-speed operation with a small load torque, the alnico magnet is magnetized in the direction to reduce the magnetic flux of the main field, and the magnetic flux interlinking with the armature coil is generated. increase.

  On the other hand, in a permanent magnet motor, a technique is known in which a rotor is divided in the axial direction and one type of permanent magnet having different characteristics is attached to each divided block (for example, see Patent Document 2). In this permanent magnet motor, the coercive force of the magnet is made different, the amount of magnetization of the low coercive permanent magnet is varied by the current of the stator winding, and the magnetic flux linked to the armature coil is varied. For example, one permanent magnet is made of rare earth and the other permanent magnet is made of alnico so that the characteristics are made different. In this technique, when the d-axis component of the rotating magnetic flux generated from the stator is increased in the negative direction, the magnetomotive force in the direction opposite to the magnet magnetic flux is increased by the low coercive force permanent magnet, so that the magnetic force of the magnet is reduced, and d When the axial component is increased in the positive direction, the low coercivity magnet increases the magnetomotive force in the same direction as the magnetic flux of the magnet, so that the magnetic force of the magnet increases, and the high coercivity permanent magnet has higher coercivity characteristics than the stator flux. Therefore, the magnetic force of the magnet is said to be kept constant.

  The operation of the permanent magnet is explained using the BH characteristic curve in the second quadrant as shown in FIG. 9, and the operation of the permanent magnet in the magnetic circuit is the same as the BH characteristic curve of the permanent magnet, the magnetic circuit and the magnet. It is determined by the permeance coefficient Pc determined by the dimensions, and operates at the intersection point p with the permeance line.

  At this time, if the d-axis component of the rotating magnetic flux generated from the stator is increased in the negative direction, negative magnetizing force is applied to the permanent magnet, and the permeance line moves in the negative (left in FIG. 9) direction to operate. The point moves to p1, and the magnetic flux density decreases to B1. On the other hand, if the d-axis component of the rotating magnetic flux generated from the stator is increased in the positive direction, a positive magnetizing force is applied to the permanent magnet, and the permeance line is translated in the positive (right side in FIG. 9) operating point. Moves to p2, and the magnetic flux density rises to B2.

Further, this technique basically uses the operation in the straight line portion (recoil wire) of the BH curve of the permanent magnet. As shown in FIG. 9, the operation is reversible (reversible demagnetization). And increased magnetization).
JP-A-8-9610 JP-A-2005-304204

  However, the above technique has the following problems. That is, in the technique using the alnico magnet, although the alnico magnet has a small magnetizing force, it requires a considerably large magnetizing force for magnetization (magnetization) and is magnetized by a d-axis or q-axis current in normal operation. It is difficult. Therefore, it is necessary to pass a large current for magnetization, and there is a problem that the current capacity of the driving device is large. Alnico magnets have a small coercive force, and partial demagnetization occurs even with normal operating current. If the thickness of the permanent magnet is increased to prevent demagnetization, magnetization by d-axis or q-axis current becomes more difficult.

  Further, in the above technique in which permanent magnets having different characteristics are attached to each divided block, the phenomenon of increasing or decreasing the amount of magnetic flux by changing the magnetic flux density to increase or decrease the d-axis component occurs only in the low coercive force permanent magnet. However, since it occurs in the same way in the high coercivity permanent magnet, it is not possible to obtain an effect simply by using the low coercivity permanent magnet and the high coercivity permanent magnet in combination. Further, since the operation is reversible, the permanent magnet returns to the original BH curve when the magnetizing force is removed, so that the magnetic flux density cannot be changed greatly.

  In view of the above circumstances, the present invention provides a permanent magnet motor and a hermetic compressor that can reduce the current required for magnetization and reduce the current capacity of the driving device. Objective.

A permanent magnet motor according to an embodiment of the present invention includes two or more types of permanent magnets having different characteristics in a rotor, and a current is passed through the stator winding by a driving device, and a magnetic field generated by the stator winding Is a permanent magnet motor that is operated by magnetizing and demagnetizing the permanent magnet and varying the amount of magnetic flux, and the permanent magnet is composed of rare earth magnets, and is magnetized and demagnetized to generate a magnetic flux. One of the permanent magnets whose amount is variable has a smaller thickness than the other permanent magnet and has a smaller coercive force. The rotor core of the rotor has a size of a permanent magnet housing hole for housing the permanent magnet. Two or more types of blocks having different punch plates are provided in combination in the axial direction of the rotor, and one type of permanent magnet is accommodated in each of the plurality of permanent magnet accommodation holes of each block, Rotor A slit hole is provided on the outer peripheral side of the permanent magnet in the iron core, and the positions on the outer peripheral side of the two types of permanent magnets are arranged at the same position when viewed from the axial direction of the rotor .

  According to the present invention, the current required for magnetization can be reduced, and the current capacity of the drive device can be reduced.

  Hereinafter, the permanent magnet motor 21 and the compressor according to the first embodiment of the present invention will be described with reference to FIGS. 1 and 2. In the figure, arrows X, Y, and Z indicate three directions orthogonal to each other. Here, the arrow Z indicates the axial direction of the rotor 24, and the arrows X and Y indicate the radial direction.

  The refrigeration cycle apparatus 1 includes a compressor 10, a condenser 11 connected to the compressor 10, an expansion device 12 connected to the condenser 11, an evaporator 13 connected to the expansion device 12, and an evaporator 13. And an accumulator 14 connected to.

  The compressor 10 is a hermetic compressor 10 configured by housing a permanent magnet motor 21 and a compression mechanism unit 22 driven by the permanent magnet motor 21 in a sealed container 23. The permanent magnet motor 21 includes a rotor 24 and a stator 25. The rotor 24 is fixed to a shaft 26 extending to the compression mechanism portion 22 and is rotatably disposed in the stator 25.

  The permanent magnet motor 21 includes two or more kinds of permanent magnets 33 and 34 having different characteristics in the rotor 24, and a current is passed through the stator winding 37 by the driving device, and one permanent magnet 34 is generated by a magnetic field generated by the winding. Is a permanent magnet motor 21 that is operated by magnetizing and demagnetizing the magnetic flux and varying the amount of magnetic flux.

  The rotor 24 includes a cylindrical rotor core 31 as a magnetic pole core disposed on the outer periphery of the shaft 26, and a plurality of permanent magnet portions provided at four locations on the rotor core 31 so as to surround the outer periphery of the shaft 26. 32.

  That is, on the outer peripheral side of the rotor core 31 of the rotor 24, for example, along the shaft 26, four permanent magnet housing holes 31a for housing the permanent magnet are provided so as to surround the shaft 26. Permanent magnet portions 32 each including a plurality of permanent magnets 33 and 34 are disposed in the four permanent magnet accommodation holes 31a.

  As shown in FIG. 2, the permanent magnet portion 32 is configured by combining two types of first permanent magnets 33 and second permanent magnets 34 having different characteristics. The first permanent magnet 33 to which the amount of magnetic flux is fixed is a high coercive force permanent magnet, and the second permanent magnet 34 whose amount of magnetic flux is variable is a low coercive force permanent magnet. Both the first permanent magnet 33 and the second permanent magnet 34 are formed in a rectangular plate shape using a rare earth magnet.

  The permanent magnet portion 32 is configured by arranging a first permanent magnet 33 in the center and arranging second permanent magnets 34 at both ends of the first permanent magnet 33. One second permanent magnet 34 is magnetized and demagnetized to vary the amount of magnetic flux. The second permanent magnet 34, which is magnetized / demagnetized to change the amount of magnetic flux, is thinner than the other first permanent magnet 33 (the size in the magnetization direction is reduced). It is easy to be demagnetized. That is, in this embodiment, the magnetization / demagnetization is made different depending on the thickness.

  The stator 25 shown in FIG. 3 has a configuration in which a stator winding 37 is concentratedly wound around a stator core 36.

  In the compressor 10 configured as described above, a second permanent magnet 34 serving as one permanent magnet that causes a current to flow through the stator winding 37 by the driving device and varies the magnetic flux by the magnetic field generated by the stator winding 37. Is operated by varying the amount of magnetic flux.

  FIG. 4 shows the relationship between the magnetizing force applied to the permanent magnet when a current for changing the magnetic flux of the permanent magnet is passed through the stator winding 37 and the thickness of the permanent magnet. It can be seen that the magnetizing force applied to the permanent magnet increases as the thickness of the permanent magnet decreases. Therefore, as the thickness is thinner, the permanent magnet can be magnetized and demagnetized with less current.

  FIG. 5 is a graph for explaining the operation of the permanent magnet according to the present embodiment. The vertical axis represents magnetic flux density (T), and the horizontal axis represents magnetizing force (A / m). The operation of the permanent magnet will be described using a BH characteristic curve in the second quadrant as shown in FIG. The operation of the permanent magnet in the magnetic circuit is determined by the BH characteristic curve of the permanent magnet and the permeance coefficient Pc determined by the dimensions of the magnetic circuit and the magnet, and operates at the intersection point p with the permeance line. That is, the permanent magnet is magnetized at the magnetic flux density B0 at this operating point p.

  As shown in FIG. 5, the permeance coefficient Pc is determined by the size of the magnetization direction of the magnetic circuit and the magnet. Therefore, if the thickness of the low coercive force permanent magnet, that is, the size of the magnetization direction is decreased, the permeance coefficient Pc is decreased. The permeance line is normally changed from Pc1 to Pc2.

  That is, as can be seen from FIG. 5, the permeance line Pc2 has an inclination that easily exceeds the bending point of the BH curve as compared with the permeance line Pc1. For this reason, irreversible demagnetization occurs with a small magnetization force, and the magnetization of the permanent magnet is easily changed irreversibly.

  If the magnetization of the permanent magnet is made irreversible, a large change in the amount of magnetic flux can be obtained, so that irreversible demagnetization and remagnetization of the permanent magnet can be used.

  As shown in FIG. 5, when a magnetizing force is applied to the second permanent magnet 34, which is a low coercive force permanent magnet, the operating point moves beyond the inflection point of the BH curve. In this way, even if the negative magnetizing force is removed, the permanent magnet does not return to the original BH curve, irreversible demagnetization occurs, the operating point becomes the p 'point, and the magnetic flux density is greatly reduced. And it is magnetized by B ′.

  On the other hand, in the first permanent magnet 33, which is a high coercive force permanent magnet, the operating point does not exceed the bending point even when a magnetizing force is applied, so that irreversible demagnetization does not occur and the original magnetic flux density is restored.

  In order to generate such irreversible demagnetization, a short negative magnetizing force is applied. That is, a current may be passed. Thereafter, when it is desired to increase the magnetic flux density of the permanent magnet, re-magnetization may be performed by applying a short positive magnetizing force.

  As described above, by utilizing the difference between the magnetization and demagnetization of the permanent magnet, by generating irreversible demagnetization only in the second permanent magnet 34 which is a permanent magnet that is easily magnetized and demagnetized, a certain amount of magnetism can be obtained. A large change in the amount of magnetic flux can be obtained after securing.

  Here, as Comparative Example 1, a permanent magnet motor in which the above-described rotor 24 is divided in the axial direction and a permanent magnet made of a material having different characteristics is provided for each divided block will be described with reference to FIGS. 9 and 10. To do.

  The operation of the permanent magnet of Comparative Example 1 will be described using a BH characteristic curve in the second quadrant as shown in FIG. The operation of the permanent magnet in the magnetic circuit is determined by the BH characteristic curve of the permanent magnet and the permeance coefficient Pc determined by the dimensions of the magnetic circuit and the magnet, and operates at the intersection point p with the permeance line. That is, the permanent magnet is magnetized at the magnetic flux density B0 at this operating point p.

  At this time, if the d-axis component of the rotating magnetic flux generated from the stator 25 is increased in the negative direction, negative magnetizing force is applied to the permanent magnet, and the permeance line is translated in the negative (left side in FIG. 9) direction. The operating point moves to p1, and the magnetic flux density decreases to B1. On the other hand, when the d-axis component of the rotating magnetic flux generated from the stator 25 is increased in the positive direction, a permanent magnetizing force is applied to the permanent magnet, and the permeance line moves in parallel in the positive (right side in FIG. 9) operation. The point moves to p2, and the magnetic flux density rises to B2.

  As described above, the magnetic flux density of the permanent magnet can be changed by increasing or decreasing the d-axis component of the rotating magnetic flux generated from the stator 25, so that the amount of magnetic flux can be increased or decreased. However, this phenomenon occurs not only in the low coercivity permanent magnet but also in the high coercivity permanent magnet. That is, it occurs in the permanent magnets in general and has no relation to the coercive force.

Further, the operating point of the permanent magnet of Comparative Example 1 moves on the BH curve, and the slope of the BH curve is expressed by the recoil relative permeability μrec. In rare earth magnets, it is close to 1 and is almost equal to the permeability 4π × 10 ⁻⁷ in vacuum. For this reason, in a normal configuration, a considerably large magnetizing force must be applied to greatly change the magnetic flux density, and a large current is required to generate a d-axis component magnetic flux.

  In the permanent magnet motor 21 of Comparative Example 1 described above, two magnets of low magnetic permeability / high coercive force and low coercive force / high magnetic permeability are combined. However, in the high magnetic permeability magnet, the slope of the BH curve is increased. The change in the magnetic flux density at the operating point due to the magnetizing force is large, and the amount of magnetic flux can be varied with a smaller current. However, this action is independent of the coercive force, and there is no point in combining a high coercivity magnet and a low coercivity magnet.

  The permanent magnet motor 21 of the comparative example 1 basically uses the operation in the straight line portion (recoil wire) of the BH curve of the permanent magnet, and the operation is reversible (reversible demagnetization and increase). Magnetism). Also, since the operation is reversible, the permanent magnet returns on the original BH curve when the magnetizing force is removed, so that the magnetic flux density cannot be changed greatly. Moreover, in order to exceed the bending point, it is necessary to magnetize in a short time. However, in a rare earth magnet, magnetization requires a large magnetizing force, that is, a current, although it is a short time. It is necessary to increase it.

  For example, in a normal design, magnetizing by the stator winding 37 requires several tens of times the normal operating current, but the element of the drive device is rated or rated even for a few ms. Can only flow up to twice the current. Therefore, in order to pass a current several tens of times the normal operating current, it is necessary to make the element have a large rated current, which greatly increases the cost.

  On the other hand, as shown in FIG. 5, the permanent magnet motor 21 of the present embodiment can change the magnetization of the permanent magnet irreversibly to obtain a large change in the amount of magnetic flux. That is, by making the thickness of one permanent magnet thin to shift the inclination of the permeance line Pc, it is possible to easily exceed the irreversible bending point. For this reason, the irreversible demagnetization and remagnetization of a permanent magnet can be utilized.

  According to the permanent magnet motor 21 and the compressor 10 according to the present embodiment, the following effects can be obtained. That is, the inclination of the permeance line can be changed as shown by Pc2 in FIG. 5 by making the thickness of the second permanent magnet 34 that changes the magnetic flux thinner than the thickness of the first permanent magnet 33 that fixes the magnetic flux. Therefore, the second permanent magnet 34 which is a low coercive force permanent magnet can be easily magnetized and demagnetized, and the bending point can be easily exceeded. For this reason, since irreversible demagnetization can be generated with a small magnetization force, the amount of magnetic flux can be varied without increasing the current capacity of the drive device (inverter).

  Further, since rare earth magnets are used for both the first and second permanent magnets 33 and 34, it is possible to magnetize with a d-axis or q-axis current in normal operation. In addition, the coercive force is larger than that of the alnico magnet, and partial demagnetization can be prevented from occurring even under normal operating current. When the operating current is divided into a component in phase with the back electromotive force of the permanent magnet motor and a component advanced in phase by 90 degrees in electrical angle, the in-phase component is defined as q-axis component and the component advanced in phase by 90 degrees. Called the d-axis component.

[Second Embodiment]
A permanent magnet motor 21 according to a second embodiment of the present invention will be described below with reference to FIG. FIG. 6A shows a perspective view of the rotor 40 of the present embodiment, FIG. 6B conceptually shows a cross section of the first block 41, and FIG. 6C conceptually shows a cross section of the second block 42. In addition, since it is the same as that of the permanent magnet electric motor 21 concerning the said 1st Embodiment and the hermetic compressor 10 except the structure of the rotor 40, common description is abbreviate | omitted.

  As shown in FIG. 6, the rotor 40 includes a cylindrical rotor core 31 disposed on the outer periphery of the shaft 26, and permanent magnets 33 and 34 provided on the rotor core 31 so as to surround the outer periphery of the shaft 26. And is configured. The rotor core 31 includes a combination of first and second blocks 41 and 42. The 1st block 41 and the 2nd block 42 are comprised by the punching board in which the permanent magnet accommodation holes 41a and 42a were formed, respectively, and the dimension of this permanent magnet accommodation holes 41a and 42a differs. That is, the rotor core 31 is composed of two or more types of punched plates having permanent magnet housing holes 41a and 42a having different dimensions.

  In the two blocks 41 and 42 of the rotor core 31 of the rotor 40, four rectangular permanent magnet housing holes 41a and 42a are provided on the outer peripheral side so as to surround the shaft 26 along the shaft 26, for example. One kind of permanent magnets 33 and 34 are disposed in the four permanent magnet receiving holes 41a and 42a, respectively.

  In the plurality of blocks 41 and 42 divided in the axial direction, permanent magnets 33 and 34 having different dimensions are respectively arranged. For example, here, a thin second permanent magnet 34 is disposed in the block 41 on the one axial side (upper side in the drawing), and the second block 42 on the other axial side (lower side in the drawing) is provided with the second permanent magnet 34. A first permanent magnet 33 that is thicker than the permanent magnet 34 is disposed. That is, the second permanent magnet 34 which is a low coercive force permanent magnet is arranged in the upper part in the drawing, and the first permanent magnet 33 which is a high coercive force permanent magnet is arranged in the lower part in the drawing, and two kinds of permanent magnets are arranged in the axial direction. They are arranged in parallel. The rotor 40 includes two types of first permanent magnets 33 and second permanent magnets 34 having different characteristics. The first permanent magnet 33 and the second permanent magnet 34 are both configured using rare earth magnets.

  The rotor core is generally laminated at the same time as punching by caulking projections, but in the progressive feeding type of the core, two permanent magnet accommodation hole punching stations with different dimensions are provided, and either one is selectively punched A rotating iron core 31 shown in FIG. 6 is obtained.

  In the permanent magnet motor 21 and the hermetic compressor 10 according to the present embodiment, the same effects as in the first embodiment can be obtained. In other words, it is necessary for magnetization because the permanent magnet 34 that changes the magnetic flux is made thin so that irreversible changes can easily occur and irreversible demagnetization and remagnetization of the permanent magnet can be used. It is possible to reduce the current and the current capacity of the driving device.

  Furthermore, by changing the axial length (stacking direction thickness) indicated by the arrow z in the drawing of each block 41, 42, the ratio of the magnets that can change the amount of magnetic flux can be easily selected.

[Third Embodiment]
A permanent magnet motor 21 according to a third embodiment of the present invention will be described below with reference to FIG. 7A conceptually shows a cross-sectional view of the first block 41, and FIG. 7B conceptually shows a cross-sectional view of the second block 42. In addition, since it is the same as that of the permanent magnet electric motor 21 concerning the said 2nd Embodiment and the hermetic compressor 10 except the structure of the rotor core 31, common description is abbreviate | omitted.

  As in the second embodiment, the rotor 40 in the present embodiment has four cylindrical rotor cores 31 disposed on the outer periphery of the shaft 26 and four locations so that the rotor core 31 surrounds the outer periphery of the shaft 26. And a plurality of permanent magnets 33 and 34 provided in the. The rotor core 31 is a combination of a first block 41 and a second block 42, and the dimensions of the permanent magnet accommodation holes 41a, 42a formed in the respective blocks 41, 42 are different.

  In this actual child form, as shown in FIG. 7, a plurality of slit holes 43 are formed on the outer peripheral side of the permanent magnets 33 and 34 in the rotor core 31 of the rotor 40. The slit hole 43 is provided for the purpose of reducing armature reaction magnetic flux or controlling the magnetic flux distribution around the rotor.

  In the two blocks 41 and 42 arranged in parallel in the axial direction, the rotor 40 is arranged so that the positions of the permanent magnets 33 and 34 are aligned on the outer peripheral side where the slit hole 43 is formed, and the position on the inner peripheral side. Is different. That is, the difference in thickness between the permanent magnets 33 and 34 is configured to be different by changing the shape and size setting of the iron core on the shaft 26 side (inner diameter side), not on the slit hole 43 side (outer periphery side). Yes. That is, when viewed from the axial direction (Z direction) of the rotor 40, the positions on the outer peripheral side of the permanent magnets 33, 34 are the same, and the two blocks 41, 42 are the same in the outer peripheral part where the slit holes 43 are formed. It is formed into a shape.

  In the permanent magnet motor 21 and the hermetic compressor 10 according to the present embodiment, the same effect as in the second embodiment can be obtained. That is, by making the permanent magnet whose magnetic flux is variable thin, it is easy to generate irreversible changes, and the irreversible demagnetization and remagnetization of the permanent magnet can be used. It is possible to reduce the current and the current capacity of the driving device. Furthermore, the shape of the slit hole 43 may be only one, and it is not necessary to change the shape and arrangement of the slit hole 43 for each of the blocks 41 and 42, and an extra die or punching process is unnecessary. Further, it is possible to prevent the shape of the punching die of the rotor core 31 from becoming complicated.

[Fourth Embodiment]
A permanent magnet motor 21 according to a fourth embodiment of the present invention will be described below with reference to FIG. In addition, since it is the same as that of the permanent-magnet motor 21 and the hermetic compressor 10 concerning the said 1st thru | or 3rd Embodiment except the material which comprises a permanent magnet, common description is abbreviate | omitted.

In this embodiment, the low coercive force permanent magnet 34, which is the second permanent magnet 34 that is magnetized and demagnetized to vary the amount of magnetic flux, is a 1-5 samarium-cobalt (which has good magnetization characteristics among rare earths). SmCo ₅ ) magnet.

As shown in FIG. 8, generally, rare earth magnets have poor magnetization characteristics. For example, neodymium / iron / boron magnets have little change in magnetization characteristics due to differences in coercive force and residual magnetic flux density, and generally require a magnetizing force of 1 to 1.5 (MA / m). On the other hand, the magnetization characteristics of the 2-17 samarium-cobalt (Sm ₂ [Co, Cu, Fe, Zr] ₁₇ ) magnet vary greatly depending on the coercive force, but it is about 0.8 to 1.2 (MA / m). Magnetizing force is required. In this case, if the coercive force is lowered, the magnetization characteristics are improved, but if the coercive force is lowered too much, irreversible demagnetization may occur during normal operation.

In contrast, the 1-5 samarium-cobalt (SmCo ₅ ) magnet used in this embodiment has a relatively high coercive force and is unlikely to cause irreversible demagnetization, but the permeance coefficient Pc is reduced by reducing the thickness. Therefore, irreversible demagnetization can be easily performed with a current that can be output by a normal driving device.

  In the permanent magnet motor 21 and the hermetic compressor 10 according to the present embodiment, the same effects as in the first embodiment can be obtained. That is, by making the second permanent magnet 34 that changes the magnetic flux thin, it is easy to generate irreversible changes, and irreversible demagnetization and remagnetization of the permanent magnet can be used. Therefore, it is possible to reduce the current required for this and to reduce the current capacity of the driving device. Furthermore, by using a material having good magnetization, it is possible to magnetize with a smaller current, and to prevent an increase in the current capacity of the driving device. Therefore, irreversible demagnetization and magnetization can be performed with a current that can be output by a normal driving device.

  The present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. For example, in FIG. 1, the two-cylinder compressor 10 having two compression chambers is illustrated, but the present invention is not limited to this. The rotors 24 and 40 are shown as a four-pole structure as an example, but are not limited thereto. Moreover, although the shape of the permanent magnet is a rectangular plate shape, the shape is not limited to this, and may be configured, for example, in a circular arc shape in a sectional view. Although the case where the stator 25 is concentrated winding is shown, it is not limited to this, and may be distributed winding, for example. Furthermore, although the case where there are two types of permanent magnets is illustrated, three or more types may be used.

Furthermore, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment.
Hereinafter, embodiments of the present invention will be described.
(1)
Two or more types of permanent magnets with different characteristics are provided in the rotor, current is passed through the stator winding by the driving device, and one of the permanent magnets is magnetized and demagnetized by the magnetic field created by the stator winding. A permanent magnet motor that is operated by varying the amount,
The permanent magnet is composed of rare earth magnets, and one of the permanent magnets, which is magnetized and demagnetized to change the amount of magnetic flux, has a smaller thickness and a smaller coercive force than the other permanent magnet. A permanent magnet motor characterized by that.
(2)
The rotor core of the rotor includes a combination of two or more types of blocks having punched plates having different dimensions of the permanent magnet housing holes for housing the permanent magnets in the axial direction of the rotor, and a plurality of blocks of the blocks. The permanent magnet electric motor according to (1), wherein one type of permanent magnet is accommodated in each permanent magnet accommodation hole.
(3)
A slit hole is provided on the outer peripheral side of the permanent magnet in the rotor core of the rotor,
(2) The permanent magnet motor according to (2), wherein the positions of the two types of permanent magnets on the outer peripheral side are arranged at the same position when viewed from the axial direction of the rotor.
(4)
The permanent magnet motor according to any one of (1) to (3), wherein a 1-5 samarium-cobalt (SmCo5) magnet is used as a permanent magnet that is magnetized and demagnetized to change the amount of magnetic flux. .
(5)
A hermetic compressor in which the permanent magnet motor according to any one of (1) to (4) and a compression mechanism portion driven by the permanent magnet motor are housed in a hermetic container.

Explanatory drawing which shows the refrigerating-cycle apparatus which concerns on 1st Embodiment of this invention. Explanatory drawing which shows notionally the cross section of the rotor which concerns on the same embodiment. Explanatory drawing which shows notionally the cross section of the stator which concerns on the same embodiment. The graph which shows the relationship between the thickness of the permanent magnet which concerns on the same embodiment, and magnetizing force. The graph which shows the operation | movement of the permanent magnet which concerns on the same embodiment, and the relationship of magnetic flux density and magnetizing force. The perspective view which shows the rotor which concerns on 2nd Embodiment of this invention. Explanatory drawing which shows notionally the cross section in the 1st block of the rotor which concerns on the same embodiment. Explanatory drawing which shows notionally the cross section in the 2nd block of the rotor which concerns on the same embodiment. Explanatory drawing which shows notionally the cross section in the 1st block of the rotor which concerns on 3rd Embodiment of this invention. Explanatory drawing which shows notionally the cross section in the 2nd block of the rotor which concerns on the same embodiment. The graph which shows the relationship between the magnetization rate and magnetizing force of the permanent magnet which concerns on 3rd Embodiment of this invention. The graph which shows the operation | movement of an example of a permanent magnet, and the relationship between magnetic flux density and magnetizing force. The graph which shows the operation | movement of an example of a permanent magnet, and the relationship between magnetic flux density and magnetizing force.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Refrigeration cycle apparatus, 10 ... Hermetic compressor, 11 ... Condenser, 12 ... Expansion apparatus,
13 ... Evaporator, 4 ... Accumulator, 21 ... Permanent magnet motor, 22 ... Compression mechanism,
23 ... Airtight container, 24.40 ... Rotor, 25 ... Stator, 26 ... Shaft,
31 ... Rotor core, 31a ... Permanent magnet accommodation hole, 32 ... Permanent magnet part,
33 ... 1st permanent magnet, 34 ... 2nd permanent magnet, 36 ... Stator core, 37 ... Stator winding,
40 ... rotor, 41 ... first block, 41a. 42a ... Permanent magnet receiving hole,
42 ... second block, 43 ... slit hole.

Claims (3)

Two or more types of permanent magnets with different characteristics are provided in the rotor, current is passed through the stator winding by the driving device, and one of the permanent magnets is magnetized and demagnetized by the magnetic field created by the stator winding. A permanent magnet motor that is operated by varying the amount,
With the above permanent magnet is constituted by using a rare earth magnet, one of the permanent magnet by magnetizing and demagnetized to vary the amount of magnetic flux to reduce the thickness than the other of the permanent magnets, reducing the coercive force ,
The rotor core of the rotor includes a combination of two or more types of blocks having punched plates having different dimensions of the permanent magnet housing holes for housing the permanent magnets in the axial direction of the rotor, and a plurality of blocks of the blocks. Each type of permanent magnet is accommodated in the permanent magnet accommodation hole, and a slit hole is provided on the outer peripheral side of the permanent magnet in the rotor core of the rotor,
A permanent magnet electric motor characterized in that the outer peripheral side positions of the two types of permanent magnets are arranged at the same position when viewed from the axial direction of the rotor. As a permanent magnet for varying the magnetic flux amount by magnetizing-demagnetized, 1-5 based samarium-cobalt (SmCo5) permanent magnet motor according to claim 1, characterized by using a magnet. A hermetic compressor in which the permanent magnet motor according to claim 1 or 2 and a compression mechanism portion driven by the permanent magnet motor are housed in a hermetic container.

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