JP2023023566A - Rotary electric machine - Google Patents

Abstract

To provide a rotary electric machine in which the deformation of a case is suppressed.SOLUTION: A motor 20 as a rotary electric machine comprises: a cylindrical stator 21; a front end frame 33 which is arranged in one in the axial direction with respect to the stator 21; a rear end frame 34 which is arranged in the other in the axial direction with respect to the stator 21; a cylindrical case 32 which is sandwiched between the front end frame 33 and the rear end frame 34 and whose inner side is fixed with the stator 21; and a through bolt 38 which fastens the front end frame 33 and the rear end frame 34 on the outer side in the radial direction to the case 32. The case 32 comprises: a stator fixing part 45 which is located in an intermediate portion in the axial direction; a first end 46 which is in contact with the front frame end 33; and a second end 47 which is in contact with the rear frame end 34. The outermost diameter position of a contact end surface 51 is located on the inner side in the radial direction in comparison to the outermost diameter position of the stator fixing part 45.SELECTED DRAWING: Figure 1

Description

The present invention relates to rotating electric machines.

As a conventional rotary electric machine, for example, one described in Patent Document 1 is known. The motor disclosed in Patent Document 1 is provided integrally with the control section. The motor shell consists of a motor case, a front frame end and a rear frame end. The front frame end and the rear frame end are fastened together by through bolts with the motor case sandwiched therebetween.

JP 2014-131463 A

Due to the axial force of the through bolt, a moment force is generated such that the radially outer portion of the rear frame end with respect to the motor case falls toward the front frame end. Therefore, compressive stress is applied to the contact portion of the motor case with the rear frame end, and there is concern that the motor case may be deformed.

The present invention has been made in view of the above points, and an object thereof is to provide a rotating electrical machine in which deformation of the case is suppressed.

The rotary electric machine of the present invention comprises a cylindrical stator (21), a first end frame (33) arranged on one side in the axial direction with respect to the stator, and a first end frame (33) arranged on the other side in the axial direction with respect to the stator. A cylindrical case (32) sandwiched between two end frames (34), a first end frame and a second end frame, and having a stator fixed inside thereof, and a first end frame radially outside the case. and a through bolt (38) fastening the second end frame.

The case has a stator fixing portion (45) located in an intermediate portion in the axial direction, a first end portion (46) in contact with the first end frame, and a second end portion in contact with the second end frame. (47, 48). If the end surface of the second end portion that is in contact with the second end frame is defined as the contact end surface (51), the outermost diameter position of the contact end surface is compared with the outermost diameter position of the stator fixing portion. Located radially inward. The outermost radial position is the radially outermost position.

As a result, compared to the conventional embodiment in which the thickness of the case is constant and the outermost diameter position of the contact end surface and the outermost diameter position of the stator fixing portion are the same, the present invention acts on the second end portion. less compressive stress. Therefore, deformation of the case can be suppressed.

1 is a vertical cross-sectional view of a driving device to which the motor of the first embodiment is applied; FIG. II-II line sectional view of FIG. The figure which looked at the front-frame end of FIG. 1 from the arrow III direction. The figure which looked at the front-frame end of FIG. 1 from the arrow IV direction. The V section enlarged view of FIG. FIG. 5 is an enlarged view showing the vicinity of the second end of the case of the motor of the second embodiment, and is a view corresponding to FIG. 5 of the first embodiment.

A plurality of embodiments will be described below with reference to the drawings. The same reference numerals are assigned to substantially the same configurations between the embodiments, and the description thereof is omitted.

[First embodiment]
As shown in FIG. 1, the driving device 10 is of an integrated electromechanical type in which a motor 20 as a rotating electrical machine and a control unit 60 are integrally provided. The control unit 60 controls the motor 20 to generate a desired torque based on externally input information and information such as motor current detected inside the control unit 60 . Torque of the motor 20 is output from the output end of the rotating shaft 26 to the outside.

Hereinafter, the direction parallel to the rotation axis O of the motor 20 will be referred to as the axial direction. A direction perpendicular to the rotation axis O is referred to as a radial direction. Moreover, the direction around the rotation axis O is described as the circumferential direction.

As shown in FIGS. 1 and 2, the control unit 60 includes a substrate 61 arranged on the rotation axis O and on the opposite side of the front frame end 33 from the stator 21 of the motor 20, and It has various mounted electronic components and a cover 62 arranged to cover the board 61 and the various electronic components.

Although illustration is omitted, the various electronic components described above include, for example, a rotation angle sensor that detects the rotation angle of the rotation shaft 26, a motor drive element that switches the energization state of the motor 20, and an external or rotation angle sensor. It includes a control circuit and the like that perform calculations based on information from sensors and the like and issue commands to motor drive elements and the like.

The motor 20 is a three-phase brushless motor and includes a stator 21, a rotor 25, and a housing 31 that accommodates them. Stator 21 has stator core 22 fixed to housing 31 and three-phase winding set 23 assembled to stator core 22 . Three-phase winding set 23 is connected to control unit 60 via bus bar 24 .

The rotor 25 has a rotating shaft 26 supported by a rear bearing 35 and a front bearing 36 and a rotor core 27 fixed to the rotating shaft 26 . The rotor 25 is provided inside the stator 21 and is rotatable relative to the stator 21 . A permanent magnet 37 is provided at one end of the rotating shaft 26 .

The housing 31 includes a case 32, a front frame end 33 as a first frame end arranged on one side in the axial direction with respect to the case 32, and a second frame end arranged on the other side in the axial direction with respect to the case 32. and a rear frame end 34 as .

Here, a first comparative embodiment in which the case has a cup shape with a bottom portion on the front side as disclosed in Japanese Patent No. 5952542 will be described. If the case is cup-shaped, it becomes difficult to secure a space for arranging the busbars. If the stack thickness of the stator core is reduced to secure the above space, the motor output will be insufficient. Also, if the busbar is made smaller, heat generation increases. In addition, if the overall length of the driving device is increased, the mountability of the device on a vehicle is reduced, and the increased weight reduces the fuel efficiency of the vehicle. On the other hand, in the first embodiment, the case 32 has a cylindrical shape instead of a cup shape. The space without the bottom is used for busbar placement.

As shown in FIGS. 1 to 5, the stator 21 is fixed inside the case 32 by shrink fitting. Case 32 is sandwiched between front frame end 33 and rear frame end 34 . The front frame end 33 has a front-side fastening portion 41 located radially outside the case 32 . The rear frame end 34 has a rear-side fastening portion 43 located radially outside the case 32 . The through bolt 38 fastens the front side fastening portion 41 and the rear side fastening portion 43 on the radially outer side of the case 32 .

Two through bolts 38 are provided. The rear fastening portion 43 has a through hole 44 through which the through bolt 38 is inserted. The front fastening portion 41 has a threaded hole 42 into which the threaded portion of the through bolt 38 is screwed. The two through bolts 38 are arranged at equal intervals in the circumferential direction.

The case 32 includes a stator fixing portion 45 positioned in the middle in the axial direction, a first end portion 46 in contact with the front frame end 33, and a second end portion 47 in contact with the rear frame end 34. have. The stator fixing portion 45 needs to have a predetermined thickness (that is, a radial thickness) for shrink-fitting the stator core 22 . The second end 47 is shaped without a flange. As a result, interference between the second end portion 47 and the through bolt 38 is avoided, and the weight of the case 32 is reduced.

Hereinafter, the end surface of the second end portion 47 that is in contact with the rear frame end 34 will be referred to as a contact end surface 51 . A portion of the rear frame end 34 that contacts the contact end surface 51 is referred to as a contacted portion 52 .

Here, a problem caused by the axial force of the through bolt 38 will be described. When the axial force of the through bolt 38 acts on the rear frame end 34 , a moment force is generated that causes the rear fastening portion 43 to fall toward the front frame end 33 . Therefore, a compressive stress is applied to the radially outer portion of the second end portion 47 in contact with the rear frame end 34 , and the case 32 may be deformed.

On the other hand, in the first embodiment, the radially outermost position of the contact end surface 51 is located radially inside the radially outermost position of the stator fixing portion 45 . Specifically, the inner diameters of the second end portion 47 and the stator fixing portion 45 are the same, but the second end portion 47 is formed thinner than the stator fixing portion 45 . As a result, compared with the second comparative embodiment in which the thickness of the case is constant and the outermost diameter position of the contact end surface and the outermost diameter position of the stator fixing portion are the same, the first embodiment has the second Compressive stress acting on the end portion 47 is reduced.

If the second end portion 47 is made thin and the contact end face 51 is made small as described above, there is concern that the case 32 may buckle and the second end portion 47 may collapse into the contacted portion 52 . On the other hand, in the first embodiment, the radial width t of the contact end surface 51 is set so as to satisfy the following formula (1). In Equation (1), σ is the stress applied to the contacted portion 52 . S is the area of the abutted portion 52 . F is the axial force of the through bolt 38; d is the inner diameter of the contact end surface 51 . σ _cy is the stress at the compression yield point of the rear frame end 34 . The material of the case 32 is, for example, cold-rolled steel plate, and the material of the rear frame end 34 is an aluminum alloy. The axial force F is maximized within a range in which the through bolt 38 does not break.
σ=2F/S=2F/[π{((d+2t)/2) ² −(d/2) ² }]<σ _cy (1)

The front frame end 33 has an outer fitting portion 53 having a cylindrical surface. The fitting portion 53 is fitted to another member. When the axial force of the two through bolts 38 across the rotation axis O acts on the front frame end 33, there is concern that the fitting portion 53 will deform into an ellipse. In contrast, in the first embodiment, the first end has a flange portion 54 that extends radially outward and abuts the front frame end 33 in the axial direction. The outer diameter of the flange portion 54 is approximately the same as the outer diameter of the front frame end 33 . The flange portion 54 serves as a resistance portion against deformation of the front frame end 33 .

The flange portion 54 has a positioning hole 56 provided in a convex portion 55 protruding radially outward. The positioning holes 56 are used for positioning in the circumferential direction when assembling the motor. The front frame end 33 has positioning portions 57 at positions corresponding to the positioning holes 56 . The protrusions 55 are also provided at positions corresponding to the front fastening portions 41 in order to avoid interference between the burrs on the edges of the flange portion 54 and the front fastening portions 41 as much as possible.

Protrusions 55 are provided at positions corresponding to the two front-side fastening portions 41, and a protrusion 55 and a positioning hole 56 are provided at positions corresponding to the vicinity of the middle of the two front-side fastening portions 41 in the circumferential direction. . If only one convex portion 55 is provided on the flange portion 54, or if the convex portion 55 is provided unevenly in the circumferential direction, there is a concern that the accuracy of the inner diameter of the case 32 may be lowered. In order to secure the inner diameter accuracy, it is effective to provide three or more protrusions 55 arranged at approximately equal intervals in the circumferential direction. In the first embodiment, the convex portion 55 is also provided on the side opposite to the positioning hole 56 with the rotation axis O interposed therebetween. The flange portion 54 has four convex portions 55 arranged at approximately equal intervals in the circumferential direction. Approximately equal spacing means that a certain amount of spacing difference is allowed.

The flange portion 54 has two cutout holes 58 arranged at approximately equal intervals in the circumferential direction, through which the through bolts 38 pass. The notch hole 58 is provided in the convex portion 55 at a position corresponding to the front side fastening portion 41 .

(effect)
As described above, in the first embodiment, the case 32 includes the stator fixing portion 45 located in the intermediate portion in the axial direction, the first end portion 46 in contact with the front frame end 33 , the rear frame end 34 and a second end 47 abutting on the . The outermost diameter position of the contact end surface 51 is located radially inside the outermost diameter position of the stator fixing portion 45 . As a result, compared to the first comparative embodiment in which the thickness of the case is constant and the outermost diameter position of the contact end face and the outermost diameter position of the stator fixing portion are the same, the first embodiment has the second Compressive stress acting on the end portion 47 is reduced. Therefore, deformation of the case 32 can be suppressed.

In the first embodiment, the second end portion 47 is formed thinner than the stator fixing portion 45 . Thereby, the compressive stress acting on the second end portion 47 can be reduced.

In the first embodiment, the radial width t of the contact end surface 51 is set so as to satisfy the formula (1). This can prevent the case 32 from collapsing into the rear frame end 34 .

In the first embodiment, the first end portion 46 has a flange portion 54 that extends radially outward and axially abuts the front frame end 33 . As a result, the flange portion 54 resists deformation of the front frame end 33, so deformation of the front frame end 33 can be suppressed. Furthermore, the flange portion 54 has four convex portions 55 that protrude radially outward and are arranged at substantially equal intervals in the circumferential direction. As a result, it is possible to suppress a decrease in the accuracy of the inner diameter of the case 32 due to the provision of only one protrusion 55 .

In the first embodiment, the flange portion 54 has a plurality of notch holes 58 through which the through bolts 38 pass and which are arranged at substantially equal intervals in the circumferential direction. As a result, the pitch between the two through bolts 38 can be minimized to suppress deformation of the case 32 .

[Second embodiment]
As shown in FIG. 6, in the second embodiment, the outermost radial position of the contact end surface 51 is located radially inside the outermost radial position of the stator fixing portion 45, as in the first embodiment. ing. Specifically, while the inner diameters of the second end portion 48 and the stator fixing portion 45 are the same, the thickness of the second end portion 48 gradually decreases from the stator fixing portion 45 side toward the contact end surface 51 . is formed in The outer wall surface of the second end portion 48 is tapered. As a result, the compressive stress acting on the second end portion 48 is reduced as in the first embodiment.

[Other embodiments]
In another embodiment, in order to position the outermost diameter position of the contact end face radially inward from the outermost diameter position of the stator fixing portion, for example, a large chamfered portion or A rounded portion may be provided.

In other embodiments, the number of through bolts 38 is not limited to two, and may be three or more.

The present invention is not limited to the above-described embodiments, and can be embodied in various forms without departing from the scope of the invention.

20 motor (rotary electric machine), 21 stator, 32 case, 33 first end frame, 34 second end frame, 38 through bolt, 45 stator fixing portion, 46 first end portion, 47, 48 second end portion, 51 contact contact surface.

Claims (6)

a cylindrical stator (21);
a first end frame (33) arranged on one side in the axial direction with respect to the stator;
a second end frame (34) arranged on the other side in the axial direction with respect to the stator;
a cylindrical case (32) sandwiched between the first end frame and the second end frame and having the stator fixed inside;
a through bolt (38) that fastens the first end frame and the second end frame on the radially outer side of the case;
with
The case includes a stator fixing portion (45) located in an intermediate portion in the axial direction, a first end portion (46) in contact with the first end frame, and a second end portion (46) in contact with the second end frame. having two ends (47, 48);
If the end surface of the second end that is in contact with the second end frame is defined as a contact end surface (51),
The rotary electric machine, wherein the outermost diameter position of the contact end surface is located radially inside the outermost diameter position of the stator fixing portion. The rotary electric machine according to claim 1, wherein said second end (47) is formed thinner than said stator fixing portion. The rotary electric machine according to claim 1, wherein said second end portion (48) is formed such that the thickness thereof gradually decreases from said stator fixing portion side toward said contact end surface. If the portion of the second end frame that is in contact with the contact end surface is defined as a contacted portion (52),
Let σ be the stress applied to the contact portion, S be the area of the contact portion, F be the axial force of the through bolt, d be the inner diameter of the contact end surface, and the radial direction of the contact end surface Assuming that the width is t and the stress at the compressive yield point of the second frame end is _σcy ,
The radial width t is
σ=2F/S=2F/[π{((d+2t)/2) ² −(d/2) ² }]<σ _cy
The rotating electric machine according to any one of claims 1 to 3, which is set so as to satisfy the first end has a flange portion (54) that extends radially outward and abuts the first frame end in the axial direction;
The electric rotating machine according to any one of claims 1 to 4, wherein the flange portion has three or more protrusions (55) that protrude radially outward and are arranged at substantially equal intervals in the circumferential direction. The rotary electric machine according to claim 5, wherein the flange portion has a plurality of notch holes (58) arranged at substantially equal intervals in the circumferential direction and through which the through bolts pass.

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