Rotating electric machine

Abstract

A rotating electrical machine is provided with: an outer housing that accommodates a stator core on the outside in the radial direction of the stator core; and an inner housing that accommodates the stator core between the stator core and the outer housing, the inner housing having a refrigerant flow path in the axial direction therein, holding the outer housing on the outside in the radial direction, and holding the stator core on the inside in the radial direction, the linear expansion coefficient of the inner housing is greater than the linear expansion coefficient of the outer housing.

Description

Technical Field

[0001] The present invention relates to rotating electrical machines. Background Art

[0002] In the continuous operation of a rotating electric machine, cooling performance is important, and in particular, cooling of the stator of the rotating electric machine in a high temperature environment is important from the viewpoint of extending the continuous operation time. For example, Patent Document 1 discloses a rotating electric machine that can dissipate heat from a stator core to a housing without causing deformation of the stator core. Prior art literature Patent Literature

[0003] Patent Document 1: Japanese Patent Application Publication No. 2020-120489 Summary of the invention Problem that the invention aims to solve

[0004] In the structure described in Patent Document 1, when a method of heat-pressing a stator core, which is an electromagnetic steel sheet, into a motor housing is adopted, since the motor housing is made of aluminum, the housing is overly tightened to the stator core at low temperatures due to the linear expansion difference. This may cause excessive stress on the housing and cracks. In addition, when the interference is reduced to avoid such stress, a gap is generated between the stator core and the housing at high temperatures, and the holding force cannot be ensured, and the core on the inner diameter side of the stator core opens. Therefore, the problem of not being able to exert the cooling effect and damaging the reliability of stator holding occurs.

[0005] An object of the present invention is to provide a rotating electrical machine capable of achieving both improvement in cooling performance and relaxation of generated stress. Technical means of solving problems

[0006] A rotating electric machine comprises: an outer shell which accommodates the stator core on the radially outer side of the stator core; and an inner shell which accommodates the stator core between the stator core and the outer shell, wherein the inner shell has a refrigerant flow path in an axial direction inside, holds the outer shell on the radially outer side, and holds the stator core on the radially inner side, and the linear expansion coefficient of the inner shell is greater than the linear expansion coefficient of the outer shell. Effects of the Invention

[0007] A rotating electrical machine capable of achieving both improved cooling performance and reduced stress can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a cross-sectional view of a rotating electrical machine according to one embodiment of the present invention. Figure 2 yes Figure 1A cross-sectional view of the motor housing. Figure 3 This is variant example 1. Figure 4 This is variant example 2. DETAILED DESCRIPTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The following descriptions and drawings are examples for illustrating the present invention, and appropriate omissions and simplifications have been made for the purpose of clarifying the description. The present invention may also be implemented in various other ways. Unless otherwise specified, each constituent element may be singular or plural.

[0010] In order to facilitate understanding of the invention, the position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

[0011] (One embodiment and overall structure of the present invention) ( Figure 1 ) The rotating electric machine 1 has a stator core 6 formed of an electromagnetic steel sheet. The stator core 6 is held by an inner housing 2 and an outer housing 7 by shrink fit or the like. The outer housing 7 accommodates the stator core 6 radially outside the stator core 6. The inner housing 2 accommodates the stator core 6 between the stator core 6 and the outer housing 7. The inner housing 2 is formed of an aluminum material, and the outer housing 7 is formed of an iron material. The present invention is a structure in which an iron annular outer housing 7 is provided on the outer periphery of the inner housing 2, which is a conventional motor housing.

[0012] The inner housing 2 has a base portion 2a and a connection portion 5. The connection portion 5 has a clearance fitting portion 4 having a through hole in the axial direction. The inner housing 2 is fixed to the rotary electric machine 1 by inserting the fixing member 3 through the clearance fitting portion 4.

[0013] ( Figure 2 ) The inner housing 2 holds the outer housing 7 on its radially outer side and holds the stator core 6 on its radially inner side. In addition, the linear expansion coefficient of the inner housing 2 is formed to be larger than the linear expansion coefficient of the outer housing 7. The volume of the inner housing 2 changes with temperature due to the properties of aluminum material. Therefore, the inner housing 2 is pressed against the stator core 6 at high temperature, and the stator core 6 is fixed.

[0014] The inner shell 2 has a plurality of bases 2a forming a refrigerant flow path 8 therein. The bases 2a are formed so as to be divided at predetermined intervals from other bases 2a adjacent to each other in the circumferential direction. A connecting portion 5 is formed between the plurality of bases 2a, the connecting portion 5 being adjacent to the bases 2a in the circumferential direction and connecting the bases 2a to each other. The connecting portion 5 is formed of a material having lower rigidity than the base 2a.

[0015] The rotating electric machine 1 has such a structure, and the inner housing 2 acts in the fastening direction at high temperature, and the plurality of bases 2a are in contact with the stator core 6. At the same time, due to the expansion of the bases 2a generated at high temperature, the outer peripheral side of the inner housing 2 is fixed with an interference generated between the outer housing 7. By maintaining the fastening by utilizing the difference in linear expansion coefficient between the stator core 6 and the inner housing 2 at high temperature, the generation of a gap between the stator core 6 and the rotating electric machine 1 can be suppressed.

[0016] In addition, the inner housing 2 can exert a cooling effect even when the gap between the stator core 6 and the base 2a is narrowed at high temperatures. Therefore, the cooling effect of the stator core 6 is maintained to help improve heat resistance, and there is no longer a restriction on staying within a specified temperature while being fixed at high temperatures.

[0017] On the contrary, at low temperatures, the inner housing 2 shrinks significantly compared to the stator core 6 and the outer housing 7. As a result, the tightening of the inner housing 2 acts in the direction of loosening at low temperatures, and the increase in interference that becomes a problem at low temperatures can be reduced. As a result, the contact pressure of the housing relative to the stator core 6 is alleviated, and the generation of excessive stress is prevented, so that the posture of the inner housing 2 at low temperatures can be maintained, and cracks in the inner housing 2 can be prevented. In addition, through these, the degree of freedom in designing the magnetic circuit is improved, and the performance of the rotating electrical machine 1 can also be improved. In addition, the reliability of holding the stator core 6 is improved.

[0018] In addition, Figure 2 In the figure, the four connecting portions 5 that connect the four base portions 2a are divided in the circumferential direction, but the base portion 2a and the connecting portion 5 may be integrally formed.

[0019] Alternatively, the stator core 6 may be fixed to the inner peripheral side of the inner housing 2 by a jig (not shown) that is press-fitted from the outer peripheral side of the outer housing 7 toward the stator core 6 .

[0020] The present invention eliminates the need for a thermostatic tank, which is a container that can maintain a constant temperature for a long time when the stator core is removed from the housing by shrink-fitting the housing when assembling the housing and the stator in the past. Instead, since the outermost ring is held by light press-fitting, shrink-fitting itself is no longer required in this structure, which can reduce man-hours and simplify equipment, and contribute to environmental protection.

[0021] In addition, according to the present invention, since a gap is provided between the stator core 6 and the inner housing 2, there is no need to worry about the stator core 6 being exposed to the outside air, the insulation effect caused by contamination, etc., and there is no need to consider the use of lubricating oil in the room of the rotating electrical machine 1, so that both reliability and productivity can be achieved.

[0022] (First Modification) ( Figure 3 ) The base 2a of the inner housing 2 is formed into a continuous circular shape, and has discard holes 9 on both sides adjacent to each other in the circumferential direction of the portion where the fixing member 3 is inserted. In this way, by forming the base 2a as a whole and forming the discard holes 9 instead of the connecting portion 5 provided in the above embodiment, the inner housing 2 no longer needs to be divided into the base 2a and provided with the connecting portion 5, which can contribute to the improvement of productivity.

[0023] (Second Modification) ( Figure 4 ) The base 2a may include a recess 10 on at least one of the outer circumferential side surface and the inner circumferential side surface of the portion between the refrigerant flow paths 8 and through which the fixing member 3 is inserted when viewed from the axial direction. Figure 4 , an example is shown in which both the outer peripheral side surface and the inner peripheral side surface of the base 2a are provided with the recessed portion 10. The recessed portion 10 has a groove in a direction opposite to a direction in which the base 2a contacts at least one of the outer housing 7 and the stator core 6.

[0024] With such a structure, the inner case 2 does not hold the outer case 7 or the stator core 6 on the surface on the side where the recess 10 is formed. Therefore, the stress on the stator core 6 or the stress on the outer case 7 generated when the inner case 2 holds the stator core 6 can be further alleviated. In addition, it can also contribute to the improvement of the assemblability of the rotating electrical machine 1.

[0025] According to one embodiment of the present invention described above, the following effects are achieved.

[0026] (1) A rotating electrical machine 1 includes an outer housing 7 that accommodates the stator core 6 on the radially outer side of the stator core 6, and an inner housing 2 that accommodates the stator core 6 between the stator core 6 and the outer housing 7. The inner housing 2 has a refrigerant flow path 8 in the axial direction inside, holds the outer housing 7 on the radially outer side, and holds the stator core 6 on the radially inner side, and the linear expansion coefficient of the inner housing 2 is larger than the linear expansion coefficient of the outer housing 7. By doing so, it is an object to provide a rotating electrical machine 1 that can achieve both improvement in cooling performance and relaxation of generated stress.

[0027] (2) The inner casing 2 includes a plurality of bases 2a having refrigerant flow paths 8. The bases 2a are formed at predetermined intervals from other bases 2a adjacent to each other in the circumferential direction. In this way, the inner casing 2 can be firmly held at high temperatures and prevented from generating excessive stress at low temperatures.

[0028] (3) The inner shell 2 includes a plurality of bases 2a having refrigerant flow paths 8 and a connection portion 5 formed of a material having lower rigidity than the base 2a. The base 2a is adjacent to the connection portion 5 in the circumferential direction. The connection portion 5 connects the plurality of bases 2a to each other between the plurality of bases 2a. The base 2a and the connection portion 5 are integrally formed. In this way, the expansion and contraction of the inner shell 2 at high temperatures and low temperatures can be handled.

[0029] (4) The base 2a has a recess 10 on at least one of the outer circumferential side surface and the inner circumferential side surface of the portion where the fixing member 3 is inserted, and the fixing member 3 fixes the inner housing 2 to the rotating electrical machine 1. The recess 10 has a groove in a direction opposite to the direction in which the base 2a contacts at least one of the outer housing 7 and the stator core 6. In this way, the holding force can be reduced on the side of the inner housing 2 where the recess 10 is provided, which can help alleviate excessive stress.

[0030] (5) The outer peripheral side of the inner housing 2 is fixed by the interference produced between the inner housing 2 and the outer housing 7. In this way, the inner housing 2 is fixed to the outer housing 7 at a high temperature.

[0031] (6) The stator core 6 is fixed to the inner peripheral side of the inner housing 2 by a jig which is pressed into the stator core 6 from the outer peripheral side of the outer housing 7. This allows stable fixation even when the fastening is relaxed at low temperatures.

[0032] In addition, the present invention is not limited to the above-mentioned embodiments, and various modifications and other configurations can be combined within the scope of the gist thereof. In addition, the present invention is not limited to the configuration having all the configurations described in the above-mentioned embodiments, and also includes a configuration in which a part of the configuration is deleted. Explanation of symbols

[0033] 1 Rotating motor 2 Inner shell 2a Base 3. Fixing components 4 Clearance fitting part 5. Connection 6 Stator core 7 Outer shell 8 Refrigerant flow path 9 Discard Hole 10 recess.

Claims

1. A rotating electric machine comprising: an outer casing that accommodates a stator core on a radially outer side of a stator core; and an inner casing that accommodates the stator core between the stator core and the outer casing, wherein: The inner housing has a refrigerant flow path in the axial direction inside, holds the outer housing on the radially outer side and holds the stator core on the radially inner side. The linear expansion coefficient of the inner housing is greater than the linear expansion coefficient of the outer housing.

2. The rotating electrical machine according to claim 1, characterized in that: The inner shell includes a plurality of bases having the refrigerant flow path, The base portions are formed to be spaced apart from other base portions adjacent to each other in the circumferential direction by a predetermined interval.

3. The rotating electrical machine according to claim 1, characterized in that: The inner shell includes: a plurality of bases having the refrigerant flow path; and a connecting portion formed of a material having lower rigidity than the base. The base portion is adjacent to the connecting portion in the circumferential direction, The connecting portion connects the plurality of bases to each other between the plurality of bases. The base portion and the connecting portion are integrally formed.

4. The rotating electrical machine according to claim 3, characterized in that: The base has a recessed portion on at least one of an outer peripheral side surface and an inner peripheral side surface of a portion where a fixing member is inserted, and the fixing member fixes the inner housing to the rotating electrical machine. The recessed portion has a groove in a direction opposite to a direction in which the base portion contacts at least one of the outer casing and the stator core.

5. The rotating electrical machine according to claim 1, characterized in that: The outer peripheral side of the inner housing is fixed by an interference produced between the inner housing and the outer housing.

6. The rotating electrical machine according to claim 1, characterized in that: The stator core is fixed to the inner peripheral side of the inner housing by a clamp that is press-fitted into the stator core from the outer peripheral side of the outer housing.

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