JP2012196034A - Reluctance motor for electric compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a synchronous motor using reluctance torque for an electric compressor which can satisfy gradually required motor output even when a rotor core of the same specification is used.SOLUTION: A motor section includes a stator 30, and a rotor 40 disposed in the stator 30 and having magnetic holding slits 43 respectively formed correspondingly to magnetic poles. In the rotor 40, point-symmetric inner slits 43a and outer slits 43b are arranged along a radial direction correspondingly to the magnetic poles. Each of the inner slits 43a is formed by connecting a first holding part 431a, a second holding part 432a and a third holding part 433a, each having a rectangular planar shape, to each other, and magnet holding lengths L1a, L2a and L3a of these holding parts in their planar direction are set to be equal to each other. Each of the outer slits 43b is formed by connecting a first holding part 431b, a second holding part 432b and a third holding part 433b to each other, and magnet holding lengths L1b, L2b and L3b of these holding parts in their planar direction are set to be equal to each other.

Description

  The present invention relates to a reluctance motor for an electric compressor constituting an air conditioner mounted on an automobile (representing a synchronous motor using reluctance torque, hereinafter referred to as a reluctance motor).

The motor for an electric compressor includes a rotor (rotor) in which permanent magnets are embedded, and a stator (stator) disposed around the rotor. The compressor is driven by fixing the rotating shaft of the compressor to the rotor. A permanent magnet is held in the rotor according to the number of poles of the motor (for example, four poles).
As the permanent magnet, an inexpensive ferrite magnet is used when cost is important, and a rare earth magnet that generates a strong magnetic force is used when motor output or downsizing is important.
Regarding the permanent magnets held by the rotor core, Patent Document 1 proposes that three or more magnetic poles are formed for each magnetic pole, and that three or more permanent magnets for each magnetic pole are formed of at least two kinds of magnet materials. According to this proposal, the selection range of the reluctance torque and the magnetic flux density can be widened, and the cost can be reduced by using a magnet material having a low magnetic flux density (for example, a ferrite magnet). .

JP 2003-000000 A

The output required for the motor for the electric compressor varies depending on the capacity of the air conditioner. In the proposal of Patent Document 1, the size of the permanent magnet embedded in the stator, the number of laminated rotors, or the motor is accommodated. It is necessary to set specifications such as the dimensions of the housing according to the output. If it does so, according to the stepwise output requested | required of a motor, the rotor or housing of a different specification must be prepared and the cost of the motor for electric compressors will be raised.
The present invention has been made based on this problem, and an object of the present invention is to provide a reluctance motor for an electric compressor that can satisfy a motor output required stepwise even if a rotor core having the same specification is used. .

For this purpose, a reluctance motor for an electric compressor according to the present invention includes a stator and a rotor. The rotor is disposed inside the stator, and a magnet holding slit is formed corresponding to the magnetic pole. In the present invention, the magnet holding slit has the following characteristic configuration.
(1) The plurality of magnet holding slits are formed along the radial direction corresponding to the magnetic poles.
(2) Each magnet holding slit is formed by a combination of three rectangular parallelepiped first holding parts, second holding parts, and third holding parts having the same magnet accommodation length in the planar direction.
(3) Each magnet holding slit is point-symmetric with respect to the center of the rotor in plan view, and is formed in a concave shape that opens outward in the radial direction.

The reluctance motor for an electric compressor according to the present invention can be used with the magnet holding slit forming a magnetic gap without holding the permanent magnet, and the permanent magnet is inserted into the magnet holding slit for use. Can be provided. The former constitutes a synchronous reluctance motor driven only by reluctance torque, and the latter constitutes an embedded magnet type motor driven by a permanent magnet torque in addition to the reluctance torque. The reluctance motor for an electric compressor according to the present invention can be used as a magnetic gap without holding a permanent magnet in a part of the magnet holding slit and holding the permanent magnet in another magnet holding slit. . In this way, by adjusting the amount (number) of permanent magnets held in the magnet holding slit 43, the reluctance motor for an electric compressor of the present invention can realize multi-stage output.
Moreover, the reluctance motor for electric compressors of this invention can comprise a some magnet holding slit from the inner side slit arrange | positioned inside radial direction, and the outer side slit arrange | positioned radially outside. . In this case, the number of permanent magnets that can be held by the inner slit can be an integral multiple of the number of permanent magnets that can be held by the outer slit. In this case, when permanent magnets having the same specifications are used, the maximum amount of permanent magnets can be held by the rotor while the magnet holding slits are used up without omission.
Furthermore, the reluctance motor for an electric compressor according to the present invention contributes to reduction if a rectangular parallelepiped permanent magnet having the same specification and easy to manufacture is used.

  According to the present invention, the output can be adjusted in multiple stages by adjusting the number of permanent magnets, including the case of functioning as a reluctance motor that does not use a permanent magnet while using a rotor core of the same specification. Can do.

It is a longitudinal cross-sectional view of the electric compressor in this Embodiment. The stator and rotor of the reluctance motor in this Embodiment are shown, (a) is a top view, (b) shows the enlarged view of a magnet holding | maintenance slit (an inner side slit, an outer side slit). The stator and rotor of the reluctance motor in the present embodiment are shown, wherein (a) shows the case where there is no permanent magnet, (b) shows the case of the minimum number of permanent magnets, and (c) shows the number of intermediate permanent magnets. (D) shows the case of the maximum number of permanent magnets. The rotor of the reluctance motor according to the present embodiment and a rotor in which a permanent magnet is held in a magnet holding slit are shown, (a) shows a case where a ferrite magnet is used, (b) shows a case where a rare earth magnet is used ( c) shows a case where a rare earth magnet and a ferrite magnet are used. The permanent magnet used for this Embodiment is shown.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
As shown in FIG. 1, in the electric compressor 10, a motor unit 20 and a scroll type compression unit 50 are accommodated in a housing 11. The electric compressor 10 is used in an air conditioner mounted on, for example, an automobile.

  As shown in FIG. 1, the refrigerant is introduced into the housing 11 from the refrigerant introduction port (not shown) formed at the end of the housing 11 on the side where the motor unit 20 is provided, and the compression unit 50 is provided. The refrigerant compressed by the compression unit 50 is discharged from a refrigerant discharge port (not shown) formed at the end on the side.

  The motor unit 20 includes a stator (stator) 30 fixed to the housing 11 and a rotor (rotor) 40 that is rotatably provided inside the stator 30. The rotor 40 is fitted to the outer peripheral portion of the main shaft 23, and both ends of the main shaft 23 are rotatably supported by the housing 11. The motor unit 20 is an embedded magnet type motor for an electric compressor having four poles.

The compression unit 50 includes a fixed scroll 51 fixed to the housing 11 and a turning scroll 52 that rotates as the main shaft 23 rotates.
In the fixed scroll 51 and the orbiting scroll 52, spiral scroll walls 51b and 52b are erected on one side of the disk-shaped end plates 51a and 52a, respectively. The fixed scroll 51 and the orbiting scroll 52 combine the scroll walls 51b and 52b to form a compression chamber between the scroll walls 51b and 52b.

  The housing 11 that forms the outer shell of such an electric compressor 10 is omitted from the illustration of the motor housing 11A that houses the motor unit 20 and the main shaft 23, the compression unit housing 11B that houses the main shaft 23 and the compression unit 50, and the like. It comprises an inverter housing 11C that houses the inverter. The motor housing 11A, the compression housing 11B, and the inverter housing 11C are integrally fastened by bolts and knock pins, respectively, and the inside is sealed.

As shown in FIG. 2, the stator 30 constituting the motor unit 20 includes a stator core 31 provided so as to surround the outer periphery of the rotor 40, and windings (illustrated) composed of electric wires attached to the stator core 31. Is omitted).
The stator core 31 has a substantially annular shape and is configured by laminating thin magnetic steel plates that are conductive materials. The stator core 31 is formed with a plurality of winding slots 33 provided at predetermined intervals in the circumferential direction on the inner peripheral wall thereof, and windings are applied to the winding slots 33. The winding slot 33 is assumed to be a distributed type as a form of winding, but the present invention is not limited to this, and can be applied to a case where winding is performed by concentrated winding. The stator core 31 generates a rotating magnetic field inside the stator core 31 by energizing the windings from the power source. The stator core 31 is formed, for example, by pressing a magnetic steel plate, such as pressing or laser processing. The same applies to the magnet holding slit 43 and the shaft through hole 45 described below.

The rotor 40 constituting the motor unit 20 includes a rotor core 41, a plurality (four in this example) of magnet holding slits 43 formed in the rotor core 41, and a shaft through hole 45 through which the main shaft 23 passes. Yes. A permanent magnet MG, which will be described later, is press-fitted into the magnet holding slit 43 and is held on the rotor core 41 via the magnet holding slit 43 by using an adhesive as necessary. In the present application, it may be simply held by the magnet holding slit 43 for convenience.
The rotor core 41 has a substantially annular shape and is formed by laminating thin magnetic steel plates. A shaft through hole 45 through which the main shaft 23 of the electric compressor 10 described above is inserted is formed at the center of the rotor core 41. The rotor core 41 is fixed to the main shaft 23 by press-fitting the main shaft 23 into the shaft through hole 45.

  Four magnet holding slits 43 corresponding to the number of poles are formed around the shaft through hole 45 at equal intervals in the circumferential direction. Each magnet holding slit 43 includes a set of an inner slit 43a and an outer slit 43b. The inner slit 43a is arranged on the inner side in the radial direction, and the outer slit 43b is arranged on the outer side in the radial direction.

  Each set of magnet holding slits 43 (inner slit 43a and outer slit 43b) is an obstacle to the passage of magnetic flux from the central axis side to the outer peripheral side of the rotor core 41 when the permanent magnet MG is not held. On the other hand, in the circumferential direction of the rotor core 41, the portions sandwiched between the adjacent magnet holding slits 43 are easy to pass magnetic fluxes from the central axis side to the outer circumferential side of the rotor core 41, and become salient pole portions.

Both the inner slit 43a and the outer slit 43b are formed in a concave shape having an opening on the outer side in the radial direction of the rotor 40, and more specifically as follows.
The inner slit 43a includes a first holding part 431a, a second holding part 432a, and a third holding part 433a. Each holding portion is formed of a rectangular parallelepiped space that penetrates the rotor core 41 in the thickness direction. The same applies to the outer slit 43b.
The first holding portion 431a, the second holding portion 432a, and the third holding portion 433a are connected to form the inner slit 43a. The first holding portion 431a, the second holding portion 432a, and the third holding portion 433a have the same magnet accommodation length L1a, L2a, L3a in the planar direction (FIG. 2B). Here, it is natural to allow a difference in error that the magnet accommodation length is equal.

  Both ends of the inner slit 43 a do not reach the outer peripheral surface of the rotor core 41. Therefore, a connecting portion 44 a is provided between each of the second holding portion 432 a and the third holding portion 433 a that make a pair and the outer peripheral surface of the rotor core 41. By providing the connecting portion 44a, the mechanical strength of the rotor 40 can be ensured. This also provides the connecting portion 44b for the outer slit 43b. And the dimension of radial direction is set equally with the connection part 44a of the inner side slit 43a, and the connection part 44b of the outer side slit 43b. That is, both ends of the inner slit 43a and the outer slit 43b are located on the same circumference.

Next, the first holding portion 431 a is disposed orthogonal to the radial direction of the rotor 40.
The second holding portion 432a has one end connected to one end of the first holding portion 431a, and the other end positioned on the outer side in the radial direction than the first holding portion 431a.
The third holding portion 433a has one end connected to one end of the first holding portion 431a, and the other end positioned on the outer side in the radial direction than the first holding portion 431a.
Each inner slit 43 a configured as described above is point-symmetric with respect to the center of the rotor 40.

The outer slit 43b includes a first holding part 431b, a second holding part 432b, and a third holding part 433b.
The first holding part 431b having a rectangular planar shape, the second holding part 432b, and the third holding part 433b are connected to form the outer slit 43b. The first holding portion 431b, the second holding portion 432b, and the third holding portion 433b have the same magnet accommodation length L1b, L2b, and L3b in the planar direction (FIG. 2B). The magnet housing lengths L1b, L2b, and L3b have the following relationship with the magnet housing lengths L1a, L2a, and L3a of the inner slit 43a described above. That is, the inner slit 43a can accommodate and hold a larger amount (twice) of the permanent magnet MG than the outer slit 43b.
L1a = 2 × L1b, L2a = 2 × L2b, L3a = 2 × L3b,

Next, the first holding portion 431 b is disposed orthogonal to the radial direction of the rotor 40. Accordingly, the first holding part 431b is parallel to the first holding part 431a of the inner slit 43a.
The second holding portion 432b has one end connected to one end of the first holding portion 431b, and the other end positioned on the outer side in the radial direction than the first holding portion 431b. The second holding part 432b is parallel to the second holding part 432a of the inner slit 43a.
The third holding portion 433b has one end connected to one end of the first holding portion 431b, and the other end positioned more radially outside the first holding portion 431b. The third holding part 433b is parallel to the third holding part 433a of the inner slit 43a.
The outer slit 43 b configured as described above is also point-symmetric with respect to the center of the rotor 40. Further, the distance Lab between the inner slit 43a and the outer slit 43b is set uniformly from one end to the other end.

The inner slit 43a and the outer slit 43b are appropriately set based on the specifications of the electric compressor 10, but are preferably set within the following range.
Angle θ1 at both ends of inner slit 43a: 0.5 to 0.6 times of polar angle (360 ° / number of poles) Angle θ2 at both ends of outer slit 43b: 0.8 to 0. of polar angle (360 ° / number of poles) 9 times embedded depth D1 of inner slit 43a: 2/4 to 2/3 of rotor 40 radius
Depth D2 embedded in outer slit 43b: 1/4 to 1/3 of rotor 40 radius

  Now, in the rotor 40 provided with the above inner slit 43a and outer slit 43b, the inner slit 43a and the outer slit 43b having a concave shape having an opening on the outer side in the radial direction of the rotor 40 function as a flux barrier. Therefore, if the magnet holding slit 43 remains a gap without holding the permanent magnet MG, the motor unit 20 functions as a synchronous reluctance motor driven only by reluctance torque. Further, if the magnet is held in the magnet holding slit 43, it functions as an embedded magnet type motor that uses a permanent magnet and a current torque as a power source in addition to the reluctance torque. Hereinafter, as described with reference to FIG. 3, the motor unit 20 according to the present embodiment including the synchronous reluctance motor can cope with various outputs while the rotor 40 has a single shape. .

  In FIG. 3A, since the magnet holding slit 43 is left as a gap without holding the permanent magnet MG, the magnet holding slit 43 serves as a flux barrier, and a portion between adjacent magnet holding slits 43 The motor unit 20 that serves as a salient pole and includes the rotor 40 functions as a reluctance motor. The motor unit 20 in this case corresponds to the minimum output because the torque by the permanent magnet MG cannot be obtained.

Next, a case where the motor unit 20 functions as an embedded magnet type motor using the permanent magnet MG will be described.
The permanent magnet MG used here has a rectangular parallelepiped shape (width W × thickness T × length L) as shown in FIG. As the permanent magnet MG, various materials such as a ferrite magnet and a rare earth magnet can be used.
As will be described later, the motor unit 20 can adjust the amount (number) of permanent magnets MG held by the magnet holding slit 43 in accordance with the output required for the motor unit 20, but in addition to this, Thus, the material of the permanent magnet MG can be selected.

3 (b) to 3 (d) show that the number of permanent magnets MG corresponding to the minimum (when the permanent magnet MG is held), the middle, and the maximum required for the motor unit 20 are the magnet holding slits. 43.
Here, as is apparent from FIGS. 3B to 3D, the inner slit 43a can hold twice as many permanent magnets MG as the outer slit 43b. A single magnet holding slit 43 (a combination of the inner slit 43a and the outer slit 43b) can hold a number of permanent magnets MG from a minimum of 1 to a maximum of 9 in stages. Hereinafter, an example of the number of permanent magnets MG that can be held by the magnet holding slit 43 will be described. The dimensions of the permanent magnet MG are the same.

Inner slit 43a:
2 (2 on the first holding part 431a)
4 (2 for the first holding part 431a, 1 for the second holding part 432a and 3rd holding part 433a)
6 (two for each of the first holding part 431a, the second holding part 432a, and the third holding part 433a)
Outer slit 43b:
1 (first holding part 431b)
3 (one for each of the first holding part 431b, the second holding part 432b, and the third holding part 433b)

As described above, the motor unit 20 adjusts the output in multiple stages by adjusting the number of permanent magnets MG, including the case of functioning as a reluctance motor without using the permanent magnet MG. Can do.
Since the motor unit 20 can realize the multistage adjustment of the number of permanent magnets MG that can be held by the magnet holding slit 43 with the rotor core 41 having the same specifications, only one type of punching die is required. This contributes to an improvement in the manufacturing efficiency of the rotor core 41 and a reduction in manufacturing costs. In addition, the fact that the rotor core 41 having the same specification can be used is based on the premise that the output of the motor unit 20 can be adjusted in multiple stages, but the housing 11 has only to have the same specification. The production efficiency is improved and the production cost is reduced. In addition, since the permanent magnet MG having the same specifications (shape, dimensions, material) and having a rectangular parallelepiped shape that is easier to manufacture than the arc shape can be used, improvement in manufacturing efficiency and manufacturing are possible from this viewpoint. Costs are reduced. In short, according to the present embodiment, the manufacturing efficiency of the electric compressor 10 is improved and the manufacturing cost is reduced.

  The example in which the output of the motor unit 20 is adjusted according to the number of permanent magnets MG has been described above, but the present invention can adjust the output of the motor unit 20 by changing the material of the permanent magnet MG. For example, FIG. 4A shows an example in which a permanent magnet FMG made of a ferrite magnet is held in the inner slit 43a, and FIG. 4B shows an example in which a permanent magnet RMG made of a rare earth magnet is held in the inner slit 43a. Show. Since the rare earth magnet has a larger magnetic force than the ferrite magnet, the output of the motor unit 20 can be increased.

  The permanent magnet MG shown in FIGS. 4 (a) and 4 (b) has a width (2W) twice that of the permanent magnet MG shown in FIG. 5 (a) as shown in FIG. 5 (b). Therefore, the single permanent magnet MG may be inserted and held in the inner slit 43a. However, even in this case, the permanent magnet MG held in the outer slit 43b is the permanent magnet MG having the width W shown in FIG. In this case, by preparing two types of permanent magnets MG having different widths, one permanent magnet MG is enough to be inserted into the inner slit 43a, so that two permanent magnets MG having a width W are used as the inner slit 43a. Compared with holding, the operation of inserting the permanent magnet MG can be simplified.

The selection of the material of the permanent magnet MG is not limited to ferrite magnets and rare earth magnets. For example, even in the same rare-earth magnet, the magnetic characteristics are different between the SmCo-based magnet and the NdFeB-based magnet, so that these can be selected. The same applies to ferrite magnets.
The present invention can also use a plurality of permanent magnets MG. FIG. 4C shows an example of this, and by arranging a permanent magnet FMG made of a ferrite magnet in the inner slit 43a and arranging a permanent magnet RMG made of a rare earth magnet in the outer slit 43b, the output of the motor unit 20 is shown. Can be adjusted. In addition, when using a ferrite magnet and a rare earth magnet, as shown in FIG.4 (c), it is preferable to arrange | position a rare earth magnet in the outer side slit 43b. Since the strength of the magnetic field (reverse magnetic field) applied from the coil is stronger toward the outside of the rotor core 41, a rare earth magnet having a strong coercive force is disposed there.

In addition to the above, as long as the gist of the present invention is not deviated, the configuration described in the above embodiment can be selected or changed to another configuration as appropriate.
For example, here, each set of magnet holding slits is constituted by two of the inner slit 43a and the outer slit 43b. However, the present invention is not limited to this, and the present invention includes three or more formed along the radial direction. Each of the magnet holding slits 43 can be configured from the slit group.
Further, when the motor unit 20 is used as the synchronous reluctance motor that does not use the permanent magnet MG, the magnet holding slit 43 (the inner slit 43a and the outer slit 43b) is normally left as a gap. However, a resin material such as an epoxy resin or an acrylic resin, or a nonmagnetic material such as a nonmagnetic metal such as aluminum, an aluminum alloy, copper, or a copper alloy may be filled.
Further, the permanent magnet MG can be held in the magnet holding slit 43 by press-fitting, but the permanent magnet MG can also be held more firmly on the rotor core 41 using an adhesive.
Furthermore, a locking claw 46 for positioning the permanent magnet MG can be provided in the magnet holding slit 43 (FIG. 2B).

DESCRIPTION OF SYMBOLS 10 Electric compressor 11 Housing 20 Motor part 30 Stator 31 Stator core 33 Winding slot 40 Rotor 41 Rotor core 43 Magnet holding slit 43a Inner slit 43b Outer slit 431a, 432a, 433a Holding part 431b, 432b, 433b Holding part 45 Shaft through hole 46 Locking claw 50 Compression part MG, FMG, RMG Permanent magnet

Claims (6)

A stator,
A rotor disposed inside the stator and having a magnet holding slit formed corresponding to the magnetic pole,
A plurality of the magnet holding slits are arranged along the radial direction corresponding to the magnetic poles,
Each of the magnet holding slits is formed by a combination of three rectangular parallelepiped first holding parts, second holding parts, and third holding parts having the same length in the planar direction.
Each of the magnet holding slits is point-symmetric with respect to the center of the rotor in plan view, and is formed in a concave shape that opens outward in the radial direction.
The synchronous motor using the reluctance motor for electric compressors characterized by the above-mentioned. The magnet holding slit constitutes a magnetic gap and is used.
A synchronous motor using the reluctance motor for an electric compressor according to claim 1. A permanent magnet is inserted into the magnet holding slit and used.
A synchronous motor using the reluctance motor for an electric compressor according to claim 1. A permanent magnet is held in a part of the magnet holding slit, and the other magnet holding slit constitutes a magnetic gap and is used for use.
A synchronous motor using the reluctance motor for an electric compressor according to claim 3. The plurality of magnet holding slits are
It consists of an inner slit arranged inside in the radial direction and an outer slit arranged outside in the radial direction,
The number of permanent magnets that can be held by the inner slit is an integral multiple of the number of permanent magnets that can be held by the outer slit.
The synchronous motor using the reluctance motor for electric compressors as described in any one of Claims 1-4. The rectangular parallelepiped permanent magnet having the same specification is held in the magnet holding slit,
The synchronous motor using the reluctance motor for electric compressors as described in any one of Claims 3-5.