rotating electrical machines

Abstract

To provide a rotary electric machine which suppresses increase in stress acting on an inner housing.SOLUTION: A rotary electric machine is constituted by housing a stator 20 and a rotor 30 in a housing 10, wherein the housing comprises: a cylindrical inner housing 11 into which the stator is inserted; a bottomed cylindrical outer housing 12 which houses the inner housing 11, a bottom 12b of the outer housing 12 comprises: a penetration part 12d through which a rotating shaft passes; and a standing part 14 which stands in an axial direction from the bottom around the penetration part, and in the inner housing 11, an inner surface of its tip is constituted as a press fit part 16 which is press-fitted to an outer surface of the standing part 14.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rotating electric machine having a stator and a rotor housed in a housing. [Background technology]

[0002] A rotating electric machine is generally configured by accommodating a stator and a rotor in a housing. Patent Document 1 describes a rotating electric machine configured by shrink-fitting a stator into a cylindrical inner housing, and press-fitting the inner housing into a cylindrical outer housing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication WO2020 / 213052 Summary of the Invention

[0004] In the conventional technology described above, inward stress is generated in the inner housing when the stator is cooled after shrink-fitting. Furthermore, inward stress is generated from the outer housing to the inner housing at the press-fit portion. Therefore, these stresses combine to apply a large inward stress to the press-fit portion of the inner housing of the rotating electric machine.

[0005] In order to cope with the stress of the press-fit portion, it was necessary to select materials and strengthen the structure, which resulted in problems such as an increase in the weight of the inner housing and higher manufacturing costs.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a rotating electrical machine that can suppress an increase in stress acting on an inner housing.

[0007] According to one aspect of the present invention, the present invention is applied to a rotating electric machine configured by housing a stator and a rotor. The housing includes a cylindrical inner housing into which the stator is fitted, and a cylindrical outer housing with a bottom that houses the inner housing. The bottom of the outer housing includes a through-hole through which a rotating shaft passes and an upright portion that rises axially from the bottom around the through-hole. The inner surface of the tip of the inner housing is configured as a press-fit portion that is press-fitted into the outer surface of the upright portion.

[0008] According to the present invention, the inner housing is subjected to inward stress on the stator fitted inside, while the press-fit portion that is pressed into the standing portion is subjected to outward stress, so that the directions in which these stresses act are opposite to each other, thereby suppressing the increase in stress when the inner housing is pressed into the outer housing. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a partial cross-sectional view of a rotating electrical machine according to this embodiment. [Figure 2] FIG. 2 is an exploded perspective view of the housing. [Figure 3] FIG. 3 is a perspective view of the inner housing. [Figure 4] FIG. 4 is a cross-sectional view of a main part of a rotating electrical machine. [Figure 5] FIG. 5 is a cross-sectional view of a main part of a rotating electric machine according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0011] Fig. 1 is a partial axial cross-sectional view of a rotating electrical machine (motor) 1 according to this embodiment. Fig. 2 is an exploded perspective view of a housing 10. Fig. 3 is a perspective view of an inner housing 11.

[0012] 1 and 2, the motor 1 includes a housing 10, a stator 20 accommodated in the housing 10, a rotor 30 rotatably provided on the inner periphery of the stator 20, and a rotating shaft 31 fixed to the rotor 30 and rotating coaxially with the rotor 30. The motor 1 receives electric power from a battery (not shown) to drive it to rotate.

[0013] The motor 1 of this embodiment is mounted on, for example, an electric vehicle and functions as an electric motor that drives the wheels. The motor 1 also functions as a generator that generates electricity (regenerates) by receiving driving force from the rotation of the wheels. The motor 1 may also be used as a drive device for devices other than automobiles, such as various electrical appliances or industrial machines.

[0014] The housing 10 has an inner housing 11 and an outer housing 12, and is configured by fitting the outer housing 12 onto the inner housing 11. The inner housing 11 and the outer housing 12 are formed by casting, for example, using an aluminum alloy as a material.

[0015] The inner housing 11 has a cylindrical shape and is composed of a cylindrical portion 11a, a tip portion 11b, and a flange portion 11c.

[0016] The cylindrical portion 11a is a cylindrical portion that houses the stator 20 inside. The tip portion 11b is configured as a surface that is narrower in diameter than the cylindrical portion 11a at one end of the cylindrical portion 11a so as to face the bottom portion 12b of the outer housing 12 and is perpendicular to the axial direction. The flange portion 11c abuts against the thick portion 12c of the outer housing 12 in the axial direction and is fastened with bolts 19, thereby fixing the inner housing 11 to the outer housing 12.

[0017] The tip portion 11b has an insertion portion 13 that opens around the rotating shaft 31, and as described below, the inner periphery of the insertion portion 13 is configured as a press-fit portion 16 that is press-fitted and fixed into the upright portion 14 formed on the bottom portion 12b of the outer housing 12.

[0018] The outer housing 12 has a cylindrical shape with a bottom, and is made up of a cylindrical portion 12a, a bottom portion 12b, and a thick portion 12c.

[0019] The tubular portion 12a is a cylindrical portion that accommodates the inner housing 11 therein. The bottom portion 12b is configured as a surface perpendicular to the axial direction at one end of the tubular portion 12a. The bottom portion 12b has a through portion 12d at its axial center, through which the rotating shaft 31 passes, and rotatably supports the rotating shaft 31 via a bearing 32. The bottom portion 12b has an upright portion 14 formed on its inner side that rises in the axial direction, and the press-fit portion 16 of the inner housing 11 is press-fitted onto the outer periphery of this upright portion 14. The upright portion 14 is formed in an annular shape so as to surround the through portion 12d. The thick portion 12c is formed at the other end of the tubular portion 12a and is thicker than the tubular portion 12a. The thick portion 12c abuts against a flange portion 11c of the inner housing 11 and is fastened with a bolt 19 to fix the inner housing 11 in the axial direction.

[0020] The cylindrical portion 12a of the outer housing 12 defines a cooling water flow path 11d between itself and the inner housing 11 that is fitted inside the cylindrical portion 12a.

[0021] More specifically, as shown in Fig. 3, radially protruding projections 111 are formed in a spiral row on the outer peripheral surface of the cylindrical portion 11a of the inner housing 11. Grooves 112 are recessed between the projections 111. The grooves 112 form spaces between themselves and the inner wall of the cylindrical portion 12a of the outer housing 12, and these spaces serve as cooling water flow paths 11d through which cooling water flows. The cooling water flow path 11d is configured so that cooling water flows in a spiral pattern around the periphery of the inner housing 11 from one side to the other in the axial direction. The cooling water flowing through the cooling water flow path 11d cools the stator 20 mounted within the housing 10.

[0022] 1, on the outer peripheral surface of the cylindrical portion 11a of the inner housing 11, a first groove 114 is formed between one end (left side in FIG. 1) of the protrusion 111 and the tip portion 11b, to which a seal member 114a is attached, for sealing between the outer peripheral surface of the inner housing 11 and the inner wall of the outer housing 12. Similarly, a second groove 115 is formed between the other end (right side in FIG. 1) of the protrusion 111 and the flange portion 11c, to which a seal member 115a is attached. Sealing members 114a, 115a, such as O-rings, are attached in the first groove 114 and the second groove 115.

[0023] Next, we will explain how to assemble the motor 1. The motor 1 is assembled by fixing the stator 20 to the inside of the inner housing 11 by so-called shrink fitting, and then press-fitting the inner housing 11 into the outer housing 12.

[0024] The stator 20 is formed so that its outer diameter is slightly larger than the inner diameter of the inner housing 11. The stator 20 is shrink-fitted, i.e., the inner housing 11 is heated to expand its inner diameter before being inserted into the inner housing 11, and as the inner housing 11 cools, the inner diameter of the inner housing 11 shrinks, bringing the inner wall of the inner housing 11 and the outer wall of the stator 20 into tight contact. This fixes the stator 20 to the inner housing 11.

[0025] 2, the inner housing 11 to which the stator 20 is fixed is inserted into the cylindrical portion 12a of the outer housing 12 through the opening 12e of the outer housing 12, and the tip end 11b of the inner housing 11 is press-fitted into the outer housing 12. Details of this press-fitting will be described later. Thereafter, the flange portion 11c of the inner housing 11 is fixed to the thick portion 12c of the outer housing 12 with bolts 19. In this way, the inner housing 11 is fixed to the outer housing 12.

[0026] As shown in FIG. 1, a cover 15 is attached to the outer housing 12 to close the opening 12e.

[0027] Here, conventionally, when the inner housing with the stator shrink-fitted thereto is press-fitted into the outer housing, the following problems have arisen.

[0028] When the inner housing is shrink-fitted, its diameter shrinks as it cools. This causes radially inward stress in the inner housing. In conventional methods, the outer periphery of the tip of the inner housing is press-fitted into the inner wall of the outer housing. When press-fitted in this way, radially inward stress is applied to the tip of the inner housing against the inner wall of the outer housing.

[0029] Therefore, the tip of the inner housing is subjected to large stresses due to these two radially inward stresses. To cope with this stress, it is necessary to select a high-strength material for the inner housing or to design a structure that can withstand the stress. This results in problems such as increased material and manufacturing costs, as well as increased weight and size.

[0030] Therefore, the present invention suppresses the increase in stress applied to the inner housing 11 by adopting the following configuration.

[0031] As shown in FIG. 1, the inner housing 11 is configured so that stress acts radially outward at a press-fit portion 16 that is press-fitted into the outer housing 12.

[0032] More specifically, the inner housing 11 has a tip end 11b formed in a wall shape perpendicular to the axial direction of the rotary shaft 31, and the inner peripheral surface of the tip end 11b is configured as a press-fit portion 16 that is press-fitted into the outer peripheral surface of the upright portion 14 of the outer housing 12. With this configuration, the press-fit portion 16 is subjected to radially outward stress relative to the outer periphery of the upright portion 14.

[0033] Therefore, as shown in Fig. 4, radially inward stress (indicated by the downward arrow in Fig. 4) acts on the inner housing 11 as it cools after shrink fitting. Furthermore, radially outward stress (indicated by the upward arrow in Fig. 4) acts on the inner housing 11 at the press-fit portion 16 of the tip end portion 11b as it is press-fitted onto the outer periphery of the upright portion 14 of the outer housing 12. These stresses act in opposite directions.

[0034] Therefore, the radially outward stress and the radially inward stress act in directions that cancel each other out near the tip end 11b of the inner housing 11. As a result, an increase in stress near the tip end 11b of the inner housing 11 is prevented.

[0035] The outer periphery of the upstanding portion 14 of the outer housing 12 and the inner periphery of the press-fit portion 16 of the inner housing 11 may be machined to be tapered to each other to facilitate press-fitting. That is, the upstanding portion 14 may be shaped so that it shrinks in the radial direction as it rises, and the press-fit portion 16 may be shaped so that it shrinks in the radial direction as it moves inward from the tip.

[0036] As described above, this embodiment is applied to a motor (rotating electric machine) 1 configured by accommodating the stator 20 and the rotor 30 within the housing 10. The housing 10 includes a cylindrical inner housing 11 into which the stator 20 is fitted, and a cylindrical outer housing 12 with a bottom that accommodates the inner housing 11. The bottom 12b of the outer housing 12 includes a through-hole 12d through which the rotating shaft 31 passes, and an upright portion 14 that stands up from the bottom 12b in the axial direction around the through-hole 12d. The inner surface of the tip of the inner housing 11 is configured as a press-fit portion 16 that is press-fitted into the outer surface of the upright portion 14.

[0037] With this configuration, the inner housing 11 is subjected to inward stress on the stator 20, which is fitted inside by shrink fitting, while the press-fit portions 16, which are press-fit into the upright portions 14 of the outer housing 12, are subjected to outward stress. As a result, the directions in which these stresses act are opposite to each other, which prevents an increase in stress when the inner housing 11 is press-fitted into the outer housing 12. This eliminates the need to design the inner housing 11 to be strong enough to withstand stress, allowing for reductions in material costs and manufacturing costs for the inner housing 11.

[0038] In addition, in this embodiment, the inner housing 11 has a cylindrical portion 11a that faces the inner surface of the tubular portion 12a of the outer housing 12, and a tip portion 11b that is formed at the tip of the cylindrical portion 11a and faces the bottom portion 12b of the outer housing 12, and the tip portion 11b has an insertion portion 13 that opens around the center of the rotating shaft 31, and the inner circumference of the insertion portion 13 is configured as a press-fit portion 16.

[0039] With this configuration, the press-fit portion 16 of the inner housing 11 is press-fitted from the outer periphery of the upright portion 14 of the outer housing 12, and is thereby configured to receive outward stress.

[0040] In this embodiment, the tip end portion 11b of the inner housing 11 is disposed so as to be positioned outside the coil ends 21 protruding from the stator 20.

[0041] With this configuration, when the stator 20 is fixed to the inner housing 11, the coil ends 21 are not exposed to the outside due to the tip end 11b, and this completely prevents the coil ends 21 from being damaged by collisions with other objects during work. Furthermore, with this shape, the portion of the inner housing 11 where the stator 20 is installed and the portion where it is press-fitted into the outer housing 12 (press-fit portion 16) are spaced apart in the axial direction. This prevents stress acting on the inner housing 11 from concentrating in one place, thereby suppressing an increase in stress at the tip end 11b of the inner housing 11.

[0042] In this embodiment, the standing portion 14 is formed in a ring shape around the through portion 12d. Therefore, the press-fit portion 16 of the inner housing 11 is press-fitted into the standing portion 14 with a uniform force in the circumferential direction.

[0043] In addition, in this embodiment, a groove portion 112 is formed on the outer peripheral surface of the inner housing 11 so as to be recessed radially inward, and the space formed between the groove portion 112 of the inner housing 11 and the inner wall of the outer housing 12 is configured as a cooling water flow path 11d through which cooling water flows.

[0044] With this configuration, the cooling water flow path 11d can be formed by the double structure of the inner housing 11 and the outer housing 12, so that the structure of the housing 10 can be simplified.

[0045] The above describes embodiments of the present invention, but the configurations described in the above embodiments and each modified example only show some of the application examples of the present invention and are not intended to limit the technical scope of the present invention.

[0046] In the above embodiment, an example was shown in which the upright portions 14 are formed circumferentially on the bottom portion 12b of the outer housing 12, but this is not limiting. Any shape may be used as long as the press-fit portion 16 of the tip portion 11b of the inner housing 11 is press-fitted radially outward of the upright portions 14, thereby securing the inner housing 11 in place. For example, the upright portions 14 may be formed as ribs that reinforce the bottom portion 12b and the through-hole portion 12d. Furthermore, instead of forming the upright portions 14 on the inner peripheral surface of the bottom portion 12b, the periphery of the through-hole portion 12d (part A in FIG. 4) may be configured as the upright portions 14 into which the press-fit portions 16 are press-fitted.

[0047] Furthermore, although the tip end portion 11b of the inner housing 11 is formed to taper in the radial direction, this is not limited thereto. For example, as shown in the cross-sectional view of the main part of a modified example in Fig. 5, the tip end portion 11b of the inner housing 11 may be formed in a cylindrical shape continuous with the cylindrical portion 11a, and the upstanding portion 14 may be formed close to the inner periphery of the tubular portion 12a of the outer housing 12 so that the inner periphery of this tip end portion 11b is press-fitted into the upstanding portion 14 of the outer housing 12. [Explanation of symbols]

[0048] 1: motor (rotating electric machine), 10: housing, 11: inner housing, 11a: cylindrical portion, 11b: tip portion, 11c: flange portion, 11d: cooling water flow path, 12: outer housing, 12a: tubular portion, 12b: bottom portion, 12c: thick portion, 12d: through portion, 12e: opening, 13: insertion portion, 14: upright portion, 16: press-fit portion, 20: stator, 21: coil end, 30: rotor, 31: rotating shaft, 111: protrusion portion, 112: groove portion, 114: first groove portion, 115: second groove portion

Claims

1. A rotating electric machine configured by housing a stator and a rotor, the housing has a double-tube structure including a cylindrical inner housing into which the stator is fitted and a bottomed cylindrical outer housing that accommodates the inner housing, a bottom portion of the outer housing including a through-hole through which the rotation shaft passes, and a rising portion that rises in an annular shape from the bottom portion in the axial direction around the through-hole, the through portion rises from the bottom portion on the same side as the upright portion in the axial direction, the inner housing has a cylindrical portion facing an inner surface of the tubular portion of the outer housing, and a tip portion facing the bottom portion, the tip portion being configured as a surface perpendicular to the axial direction by reducing in diameter from the cylindrical portion at a tip of the cylindrical portion, the tip portion includes an insertion portion that opens in an annular shape around the rotation shaft, and an inner periphery of the insertion portion is configured as a press-fit portion that is press-fitted into an outer surface of the upright portion, A rotating electric machine, wherein a space exists between the upright portion and the through portion in a radial direction perpendicular to the axial direction.

2. 2. The rotating electric machine according to claim 1, The tip end portion is disposed outside a coil end that protrudes from the stator in the axial direction. Rotating electric motor.

3. 3. The rotating electric machine according to claim 1, A groove portion is formed on the outer peripheral surface of the inner housing so as to be recessed radially inward, a space formed between the groove of the inner housing and the inner wall of the outer housing as a cooling water flow path through which cooling water flows; Rotating electric motor.

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