JP2008113492A - Electric motor and electric compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric motor which can prevent deficiencies, such as cracks, even if a housing and a stator core expand or contract, in the direction of the tightening degree becoming tighter due to a difference in the thermal expansion coefficient between the components, and to provide an electric compressor that uses the electric motor. <P>SOLUTION: In the electric motor wherein the annular stator core comprising a material with the thermal expansion coefficient different from that of the housing is fixed to the inside of the housing; an annular space part is formed between the inner circumferential surface of the housing and the outer circumferential surface of the stator core; and three or more fixing members are disposed in the space in the circumferential direction and allow the stator core to be fixed to the housing via the fixing member. The electric compressor that uses the electric motor is also provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electric motor and an electric compressor using the electric motor, and more particularly to an electric motor that solves a problem associated with a difference in thermal expansion between different materials, and an electric motor that drives a compression mechanism using the electric motor. It relates to a compressor.

  There are various types of electric compressors that incorporate an electric motor and drive the compression mechanism by the electric motor. Such an electric motor generally has a stator core fixed inside a housing (in the case of an electric compressor, the electric motor housing and the compressor housing are often combined). A structure in which a rotor of a motor is rotatably arranged inside is adopted.

When fixing the stator core in the housing, for example, a method in which the stator core is directly fitted into the housing, a method in which the stator core is fitted through an intermediate annular member, or a method of press-fitting (for example, Patent Document 1), the housing, the stator core side A method of performing pressure relief shape processing, shrink fitting and press fitting is known.
JP 2003-343438 A

  However, when the stator core is fixed to the motor housing and is fixed by shrink fitting or press fitting, the following problems occur when the ambient temperature changes greatly from a low temperature to a high temperature. For example, the ambient temperature of an electric compressor, especially where a car air conditioner electric compressor is installed, varies greatly from low temperature to high temperature, but the motor housing and stator core are made of different metals, and their linear expansion rates differ. (For example, the coefficient of thermal expansion: aluminum> iron), the stress between the two members caused by the atmospheric temperature may cause cracking of the motor housing or loosening of the motor fixing.

  The tightening allowance between the housing and the stator core is normally set in advance so as not to loosen even when the electric compressor becomes hot. Therefore, conversely, when the electric compressor is at a low temperature, there is a problem that the tightening degree becomes excessively high, and there is a possibility that problems such as cracks may occur in either of them.

  Therefore, the problem of the present invention is that, as described above, even if the housing and the stator core are expanded or contracted in the direction in which the tightening is tightened due to the difference in thermal expansion coefficient between them, problems such as cracks occur. An object of the present invention is to provide an electric motor capable of preventing this, and an electric compressor using the same.

  In order to solve the above-mentioned problems, an electric motor according to the present invention is an electric motor in which an annular stator core made of a material having a coefficient of thermal expansion different from that of the housing is fixed inside the housing. An annular space is formed between the surface and the outer peripheral surface of the stator core, and three or more fixing members are arranged in the space in the circumferential direction, and the housing is interposed via the fixing member. The stator core is fixed.

  By adopting such a configuration, the housing and the stator core are fixed via fixing members that are intermittently arranged in the circumferential direction. Between the fixing members, an annularly extending gap portion is formed. To be left. Therefore, there is a difference in the coefficient of thermal expansion between the materials of the housing and the stator core, and even if a difference in the amount of thermal expansion occurs between the two members, the difference is mostly absorbed by the gap. As a result, it is possible to prevent problems such as cracks from occurring even if the members are expanded or contracted in a direction in which the tightness of both members is tightened due to the difference in thermal expansion coefficient. The stress generated between the two members due to the difference in the coefficient of thermal expansion is locally generated only at the site of the fixing member that is intermittently arranged. Therefore, the generated stress is greatly relieved by the absorption of the deformation amount by the gap, and it is possible to prevent the occurrence of defects such as cracks from this surface as well.

  In such an electric motor according to the present invention, the fixing member can take various forms. For example, it can be formed into a member (pin-shaped member) having a circular cross-sectional shape. Alternatively, it can be formed into a member having a half-moon shaped cross section. Alternatively, it can be formed in a plate-like member having a flat plate (band flat plate) shape or a plate shape curved in an arc shape. Moreover, the fixing member of these shapes can also be formed in a hollow member. If the hollow member is formed, the fixing member itself can be expected to be elastically deformed. Therefore, it is possible to greatly relieve local stress generated in the fixing member portion.

  Furthermore, the fixing member can be formed as a spring pin having one cut in the circumferential direction. With such a spring pin configuration, the fixing member itself can be expected to be elastically deformed, so that it is possible to greatly relieve the local stress generated in the fixing member portion.

  In any form of fixing member, the length of the fixing member in the motor shaft direction is not particularly limited. The stator core may extend over substantially the entire length, or may extend partially in the axial direction.

  Further, a groove into which a part of the fixing member is fitted can be formed on the outer peripheral surface of the stator core and / or the inner peripheral surface of the housing in correspondence with the position of the fixing member. In this way, the fixing member can be reliably determined at a desired position. The magnitude relationship between the groove length and the fixing member length, the fixing member arrangement position in the groove extending direction, and the like are not particularly limited, and may be set as appropriate.

  The fixing member is preferably made of stainless steel. By using stainless steel as the material, the fixing member can be arranged without affecting the magnetic path of the stator core.

  Furthermore, it is preferable that the fixing member is disposed at a position corresponding to the teeth portion of the stator core. Since the outer peripheral position of the stator core corresponding to the teeth portion is a position where the influence can be suppressed magnetically even if a fixing member is provided, the desired fixing state as described above is achieved by providing the fixing member. However, the original performance of the motor can be reliably maintained.

  The present invention also provides an electric compressor incorporating the electric motor as described above. In particular, an electric compressor used in a car air conditioner or the like is exposed to an environment in which the temperature changes greatly, and thus the advantages of the stator core fixing structure with the fixing member interposed as described above are maximally exhibited.

  As described above, according to the electric motor and the electric compressor using the electric motor according to the present invention, even if the members are expanded or contracted in the direction in which the tightness of the two members is tightened due to the difference in the coefficient of thermal expansion between the housing and the stator core. It is possible to reliably prevent the occurrence of defects such as cracks. In addition, by optimizing the material and arrangement position of the fixing member, even if the fixing member is provided, an increase in so-called stator iron loss can be prevented, and the original performance of the motor can be reliably maintained. .

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an example of an electric compressor to which an electric motor according to the present invention is applied. In FIG. 1, reference numeral 1 denotes the entire electric compressor, and the electric compressor 1 includes a compression unit 2 and a motor unit 3 for fluid (for example, refrigerant). In this embodiment, the compression unit 2 includes a compression mechanism 6 including a fixed scroll 4 and a movable scroll 5, and the movable scroll 5 is prevented from rotating via a ball coupling 7, and the drive bearing 8 is rotated by a drive shaft 9 that is formed integrally with the motor shaft via an eccentric bush 10 disposed at the tip of the drive shaft 9. The drive shaft 9 is rotatably supported by bearings 11 and 12. The rear housing side of the compressor is configured as a motor housing 13, and an electric motor D is built in the motor housing 13.

  The electric motor D includes a stator core 14 that is fixed inside the housing 13 and a rotor 15 that rotates within the stator core 14. The rotor 15 is fixed to the drive shaft 9 and rotates integrally with the drive shaft 9. It is possible.

  In the electric motor D, as shown in FIG. 2, an annular gap 16 is formed between the inner peripheral surface of the housing 13 and the outer peripheral surface of the stator core 14. The width of the gap 16 (difference between inner and outer diameters) is set to a dimension that can absorb the difference in thermal expansion between the housing 13 and the stator core 14. In the gap portion 16, three or more fixing members 17 are disposed in the circumferential direction. In the present embodiment, the three fixing members 17 are equally distributed in the circumferential direction (every 120 degrees). Arrangement). The stator core 14 is fixed to the housing 13 via these fixing members 17. Further, in this embodiment, grooves 18 are formed on the outer peripheral surface side of the stator core 14 in correspondence with the positions where the fixing members 17 are arranged, and a part of each fixing member 17 is fitted in each groove 18. As a result, each fixing member 17 is positioned at a predetermined position. Further, in the present embodiment, the fixing member 17 is made of stainless steel and has a round bar shape with little magnetic influence, and the teeth portion 19 of the stator core 14 having the least magnetic influence is formed. It is arranged at a position corresponding to.

  In the electric motor D configured in this way, the housing 13 and the stator core 14 are fixed via fixing members 17 that are intermittently arranged in the circumferential direction, and the portions between the fixing members 17. Is left as a gap 16 extending annularly. There is a difference in coefficient of thermal expansion between the materials of the housing 13 and the stator core 14, and even if a difference in the amount of thermal expansion occurs between the two members, most of the difference is absorbed by the gap 16 and the thermal expansion. Even if the two members expand or contract in a direction in which the tightening degree of both members is tightened due to the difference in rate, it is possible to prevent the occurrence of problems such as cracks. The stress generated between the members 13 and 14 due to the difference in thermal expansion coefficient is locally generated only in the portion of the fixing member 17 that is intermittently arranged, and both sides of the stress generating portion. Since there is always a gap portion 16, the generated stress is greatly relieved by absorbing the deformation amount by the gap portion 16, and it is possible to prevent the occurrence of defects such as cracks from this aspect as well. It becomes. Further, as described above, the fixing member 17 is made of stainless steel and disposed at a position corresponding to the tooth portion 19 of the stator core 14 having the least magnetic influence, so that the original function of the electric motor D is maintained as it is. The

  The fixing member can be formed in various shapes as described above. For example, as shown in FIG. 2, the fixing member 21 having a half-moon-shaped cross section may be used. In FIG. 2, an embodiment without a groove for the fixing member 21 is shown, but a groove can be provided on the inner peripheral surface side of the housing 13, for example.

  Further, as shown in FIG. 4, a fixing member 31 made of a spring pin having a single cut in the circumferential direction can be used, or as shown in FIG. The member 41 can also be used. With such a shape, it becomes possible to absorb the local stress generated in this portion more efficiently by utilizing the elastic deformation of the fixing members 31 and 41. However, as the shape of the fixing member, any shape can be appropriately adopted as necessary.

  The structure of the electric motor according to the present invention can be applied to any motor that fixes a stator core in a housing, and is particularly suitable for an electric compressor for a car air conditioner or the like that is used in an environment with a severe temperature difference. .

It is a longitudinal cross-sectional view which shows an example of the electric compressor used as the application object of the electric motor which concerns on this invention. It is a cross-sectional view of the motor part of the electric compressor of FIG. It is a cross-sectional view which shows another structural example of the motor part of an electric compressor. It is a perspective view which shows another example of a shape of the member for fixing. It is a perspective view which shows another example of a shape of the member for fixing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric compressor 2 Compression part 3 Motor part 4 Fixed scroll 5 Movable scroll 6 Compression mechanism 7 Ball coupling 8 Drive bearing 9 Drive shaft 10 Eccentric bushes 11 and 12 Bearing 13 Housing 14 Stator core 15 Rotor 16 Air gap parts 17, 21, and 31 , 41 Fixing member 18 Groove 19 Teeth part D Electric motor

Claims (10)

  In an electric motor in which an annular stator core made of a material having a coefficient of thermal expansion different from that of the housing is fixed inside the housing, an annular gap is formed between the inner peripheral surface of the housing and the outer peripheral surface of the stator core In addition, the electric motor is characterized in that three or more fixing members are disposed in the gap portion in the circumferential direction, and the stator core is fixed to the housing via the fixing members.   The electric motor according to claim 1, wherein the fixing member is a member having a circular cross-sectional shape.   The electric motor according to claim 1, wherein the fixing member is formed as a member having a half-moon shape in cross section.   The electric motor according to claim 1, wherein the fixing member is formed as a plate-like member.   The electric motor according to claim 1, wherein the fixing member is formed of a spring pin having one cut in the circumferential direction.   The electric motor according to claim 1, wherein the fixing member is formed as a hollow member.   The groove | channel by which a part of fixing member is fitted is engraved by the outer peripheral surface of a stator core or / and the inner peripheral surface of a housing corresponding to the arrangement | positioning position of the said fixing member. The electric motor according to claim 6.   The electric motor according to claim 1, wherein the fixing member is made of stainless steel.   The electric motor according to claim 1, wherein the fixing member is disposed at a position corresponding to a tooth portion of the stator core.   An electric compressor including the electric motor according to any one of claims 1 to 9.

Images