JP7447375B2 - Motor unit and motor unit manufacturing method - Google Patents

Description

The present invention relates to a motor unit incorporating a brushless motor and a rotation detection device such as a resolver, and a method for manufacturing the same.

BACKGROUND ART Conventionally, a motor unit is known in which a resolver is fixed to a case containing a brushless motor (hereinafter referred to as a motor), and the rotational position of the motor is accurately detected by the resolver, thereby controlling the drive of the motor. A stator of the motor is fixed to, for example, a cylindrical case with a bottom. Further, a rotor of the motor is fixed to a shaft, and the shaft is rotatably supported by a case via a bearing. The resolver is fixed to a cover (bracket) provided separately from the case in alignment with the stator of the motor. This cover is attached to the case so as to close the end surface thereof (see Patent Documents 1 to 3).

Japanese Patent Application Publication No. 05-022878 Japanese Patent Application Publication No. 07-212993 Japanese Patent Application Publication No. 2019-122177

In the motor unit described above, if force (torque) in the rotational direction is applied to the cover to which the resolver is fixed, the position of the cover (end bell) relative to the case (housing) will shift, resulting in optimal adjustment. There is a risk that the resolver mounted on the cover may shift relative to the motor stator. For example, in an optional motor unit where an electromagnetic brake device is fixed to the cover to restrain rotation of the rotor, activating the electromagnetic brake device applies torque to the cover, causing the cover to move slightly in the direction of rotation. may move to.

Such a positional shift causes a shift in the rotor rotational position information detected by the resolver, and is one of the factors that reduce motor performance. Note that regardless of the presence or absence of an electromagnetic brake device, there is a possibility that the cover may be displaced due to some external force acting on the cover. Therefore, in order to maintain the detection accuracy of the resolver, it is desirable to suppress the displacement of the cover as much as possible even in a motor unit that does not have an electromagnetic brake device.

One of the purposes of this case is to provide a motor unit and its manufacturing method that can ensure the detection accuracy of the rotor rotational position detected by a resolver with a simple configuration, which was created in light of the above issues. The goal is to provide the following. In addition, this purpose is not limited to this purpose, and other purposes of this case may include effects derived from each configuration shown in "Details for Carrying Out the Invention" described later, which cannot be obtained with conventional techniques. It can be positioned as a purpose.

The disclosed motor unit includes a housing to which a stator of a motor is fixed and a rotor of the motor is rotatably supported, and an end bell to which a rotation detection device is attached and joined to the housing via a fastening member. . Further, a first hole formed in one of the housing and the end bell, through which the fastening member is inserted, and a second hole formed in the other of the housing and the end bell, through which the fastening member is inserted. Be prepared. The first hole has a flange that protrudes from an inner wall of the first hole toward the second hole and comes into surface contact with the second hole at a joint surface of the housing and the end bell.

Further, the disclosed method for manufacturing a motor unit includes a motor unit in which a housing in which a stator of a motor is fixed and a rotor of the motor is rotatably supported, and an end bell in which a rotation detection device is mounted are joined by a fastening member. This is a method of manufacturing the unit. First, a first hole through which the fastening member is inserted and a flange protruding in a diametrical direction from an inner wall of the first hole are formed in one of the housing and the end bell. Further, a second hole portion through which the fastening member is inserted is formed in the other of the housing and the end bell. When assembling the housing and the end bell, in order to bring the flange into surface contact with the second hole, the first hole is aligned with the position of the first hole and the second hole. Insert a burring punch into the section.

According to the disclosed motor unit and motor unit manufacturing method, resolver detection accuracy can be maintained with a simple configuration.

FIG. 2 is a cross-sectional view schematically showing the structure of a motor unit as an example. FIG. 2 is a cross-sectional view for explaining the structure of a joint between the housing of the motor unit shown in FIG. 1 and the end bell. FIG. 3 is a cross-sectional view for explaining the structure of the joint shown in FIG. 2, in which (A) is a cross-sectional view of the end bell before joining, and (B) is a cross-sectional view of the housing before joining. (A) to (C) are cross-sectional views for explaining the procedure of burring processing. 3 is a flowchart illustrating a method for manufacturing a motor unit. It is a sectional view showing the structure of the joint part as a modification. FIG. 7 is a cross-sectional view schematically showing the structure of a motor unit as a modified example.

[1. Configuration]
Hereinafter, a motor unit 10 as an embodiment (application example) and a method of manufacturing the same will be described with reference to the drawings. FIG. 1 is a sectional view schematically showing the structure of a motor unit 10 as an example. The motor unit 10 houses a motor 11 and a resolver 16 that is a rotation detection device. The motor 11 is, for example, a brushless DC motor, and includes a stator 12 (motor stator) including a coil and a rotor 13 (motor rotor) formed of a permanent magnet.

As shown in FIG. 1, the stator 12 and rotor 13 are housed in the housing 1. Of the stator 12 and the rotor 13, the stator 12 is fixed to the housing 1. Further, the rotor 13 is fixed to a shaft 14 that is a rotating shaft of the motor 11. The shaft 14 is rotatably supported by the housing 1 and the end bell 2 via a bearing 15. The housing 1 illustrated in FIG. 1 is formed into a bottomed cylindrical shape with an open top surface. The shaft 14 is provided so as to pass through the bottom surface of the housing 1, and a bearing 15 is disposed at the location where the shaft 14 passes through. Although the housing 1 has a container shape with a bearing 15 installed at the bottom, the housing 1 is not limited to this, and may be cylindrical, and the bottom (with the bearing 15) may be prepared as a separate front bell and assembled.

An opening on the upper surface side of the housing 1 is closed by an end bell 2. The end bell 2 is a cylindrical container with an open bottom and a bottom, and a resolver 16 is mounted inside the flat surface thereof. The resolver 16 has a resolver stator 17 and a resolver rotor 18. As shown in FIG. 1, the resolver stator 17 is fixed to the end bell 2, and the resolver rotor 18 is fixed to the shaft 14. The shaft 14 is provided so as to pass through the top surface of the end bell 2, and a bearing 15 is disposed at the location where the shaft 14 passes through.

The material of the housing 1 is, for example, an aluminum alloy containing a zinc alloy or steel, and the material of the end bell 2 is, for example, an aluminum alloy containing a zinc alloy. These housing 1 and end bell 2 are manufactured using techniques such as die casting and low pressure casting. Further, the material hardness of the housing 1 is preferably set to be higher than the material hardness of the end bell 2. In other words, it is preferable that the material of the housing 1 is at least the same material as the end bell 2 or a harder material than the end bell 2.

A brake device 19 (electromagnetic brake) as an optional equipment may be installed on the outside of the flat part of the end bell 2 (the upper side of the end bell 2 in FIG. 1). The brake device 19 is a device for decelerating the rotation of the shaft 14 or restraining the rotation to maintain the stopped state. If these functions are unnecessary, the brake device 19 is omitted. In this embodiment, the brake device 19 is fixed to the outside of the flat surface of the end bell 2 via the fastening member 5. Specific examples of the fastening member 5 include bolts, nuts, screws, tapping screws, caulking pins, rivets, and the like. Although the number of fastening parts by the fastening member 5 is not limited, for example, the fastening member 5 is attached to a plurality of positions that are rotationally symmetrical about the rotation axis of the shaft 14.

FIG. 2 is an enlarged sectional view showing a fastening location where the housing 1 and the end bell 2 are joined. The end bell 2 is joined to the housing 1 via a fastening member 5. The fastening member 5 for joining the end bell 2 does not need to be the same type of component as the fastening member 5 for fixing the brake device 19. Moreover, the cross-sectional view shown in FIG. 2 represents the state immediately before the fastening member 5 is inserted. The end bell 2 is provided with a first hole 3 into which the fastening member 5 is inserted. Further, the housing 1 is also provided with a second hole 4 through which the fastening member 5 is inserted.

The first hole 3 is provided with a cylindrical inner wall 21 and a flange 6 protruding from the inner wall 21. The inner wall 21 is formed to have a hole diameter that allows the fastening member 5 to be inserted therethrough with a sufficient margin. Further, the flange 6 is provided in a conical shape so as to protrude from the inner wall 21 near the joint surface between the housing 1 and the end bell 2 (the lower side of the first hole 3 in FIG. 2). In the state shown in FIG. 2 (a cross section passing through the hole center of the first hole 3), the flange 6 projects obliquely toward the inside and downward of the first hole 3. In other words, the flange 6 is formed in a shape that is inclined with respect to the axis (fastening direction) of the fastening member 5 in a cross section passing through the axis of the fastening member 5 . Further, the lower surface side of the flange 6 is provided so as to be in surface contact with the inside of the second hole 4.

FIG. 3(A) is a cross-sectional view showing the shape of the first hole 3 when manufacturing the end bell 2. As shown in FIG. When manufacturing the component, the protruding direction of the flange 6 is set to be perpendicular to the inner wall 21 (diameter reduction direction). The protruding direction of the flange 6 is changed by a burring process performed after the housing 1 and the end bell 2 are joined. This burring process will be described later. Further, the protrusion dimension of the flange 6 from the inner wall 21 is set to such a length that the flange 6 does not interfere with the fastening member 5 after the burring process.

The second hole portion 4 is provided with a flange receiving surface 7, a hole wall 8, an inner cylindrical surface 22, and a conical surface 23. The flange receiving surface 7 is a planar portion that makes surface contact with the flange 6. The flange receiving surface 7 shown in FIG. 2 is formed into a conical shape with an enlarged diameter at the end on the first hole 3 side. Further, the hole wall 8 is a surface that constitutes the inner wall of the hole through which the fastening member 5 is inserted. The hole wall 8 shown in FIG. 2 is formed with a thread groove that engages, for example, with the thread 9 of the fastening member 5, and the fastened state is maintained by these threaded engagements. When the fastening member 5 is a tapping screw, the threads 9 of the fastening member 5 are screwed into the hole wall 8 and fixed.

FIG. 3(B) is a cross-sectional view showing the shape of the second hole 4 during manufacture of the housing 1 component. The inner cylindrical surface 22 is a cylindrical surface having a larger diameter than the hole wall 8, and the conical surface 23 is a planar portion connecting the inner cylindrical surface 22 and the hole wall 8. These inner cylindrical surface 22 and conical surface 23 are chamfered to facilitate insertion of the fastening member 5.

[2. Burring processing]
In the manufacturing process of the motor unit 10, when the housing 1 and the end bell 2 are assembled, immediately before the fastening member 5 fastens, the fastening location is burred to shape the flange 6. The burring process in this embodiment is a process in which the flange 6 is bent and deformed until it comes into surface contact with the second hole part 4 by inserting the burring punch 24 into the first hole part 3 and the second hole part 4. means. By performing such machining at the current location, even if the coaxiality of the first hole 3 and the second hole 4 is slightly misaligned during assembly, wobbling in the rotor rotation direction between the housing 1 and the end bell 2 can be prevented. This prevents the end bell 2 from being misaligned after it is assembled to the housing 1.

FIGS. 4(A) to 4(C) are cross-sectional views for explaining the procedure of burring. A burring punch 24 shown in FIG. 4(A) is used as a tool for burring. The burring punch 24 is provided with a first cylindrical surface 25, a pressing surface 26, and a second cylindrical surface 27. The first cylindrical surface 25 is a cylindrical surface corresponding to the inner wall 21 of the first hole 3 . The pressing surface 26 is a surface for pressing the flange 6 to bend and deform it, and is formed in a conical shape corresponding to the flange receiving surface 7. The second cylindrical surface 27 is a cylindrical surface having a smaller diameter than the first cylindrical surface 25, and is formed in a cylindrical shape corresponding to the inner cylindrical surface 22 of the second hole 4.

Next, the procedure for burring will be explained. First, the housing 1 and the end bell 2 are positioned and fixed using equipment (not shown) such that the first hole 3 and the second hole 4 are coaxially aligned. In this equipment, a burring punch 24 is also arranged so as to be coaxial with the first hole 3. Further, as shown in FIG. 4(A), a burring punch 24 is inserted into the first hole 3 from the end bell 2 side. At this time, the first cylindrical surface 25 of the burring punch 24 is guided by the inner wall 21 of the first hole 3, and the burring punch 24 is guided deep into the first hole 3.

The burring punch 24 is loaded downward while the pressing force is controlled by a checker (not shown) disposed in the equipment, and the pressing surface 26 presses the flange 6 to bend and deform it. When the flange 6 is pressed against the flange receiving surface 7 by the pressing surface 26, the pressing force sensed by the checker increases more than during bending deformation, and when it exceeds a certain value, the equipment stops applying the load to the burring punch 24. programmed to stop. Thereby, the flange 6 and the flange receiving surface 7 come into surface contact, and the assembly position of the end bell 2 with respect to the housing 1 is fixed.

Note that the contact between the flange 6 and the flange receiving surface 7 may be such that there is a gap partially, or it is sufficient that the flange 6 and the flange receiving surface 7 are in contact with each other partially.
After that, the burring punch 24 is pulled out. Thereafter, as shown in FIG. 4(B), the fastening member 5 is inserted into the first hole 3 and the second hole 4, and the housing 1 and the end bell 2 are fastened and fixed. When the fastening member 5 is a tapping screw, the thread 9 of the fastening member 5 is screwed into the hole wall 8 of the second hole portion 4 and fixed, as shown in FIG. 4(C).

[3. Flowchart]
FIG. 5 is a flowchart for explaining the outline of the method for manufacturing the motor unit 10. Step A1 is a process related to manufacturing the end bell 2, and Step A2 is a process related to manufacturing the housing 1. The order of these steps is not critical; they may be performed in the reverse order, or may be performed simultaneously. Further, steps A3 to A5 are steps related to assembling the housing 1 and the end bell 2, and are performed after steps A1 and A2.

Although the attachment of the resolver 16 onto the end bell 2 is omitted in the flowchart, it is assumed that the resolver 16 is adjusted and attached to the optimal position relative to the stator 12 of the motor 11 after all the fastening members have been fixed. The mounting surface on the end bell 2 may be either on the motor 11 side (lower side in FIG. 1) or on the opposite side to the motor 11 (upper side in FIG. 1) with respect to the rotor axial direction.
In addition, when attaching the resolver 16 to the motor 11 side, as shown in FIG. 7 mentioned later, the housing 1 may be made into a cylindrical shape, and the bottom part may be prepared as a separate front bell 31. By assembling the front bell 31 to the cylindrical housing 1 after attaching the resolver 16, the motor unit 10 can be assembled.

In step A1, a first hole 3 into which the fastening member 5 is inserted is formed in the end bell 2. As shown in FIG. 3(A), the inner wall of the first hole 3 is provided with a flange 6 that protrudes in the diameter reduction direction. Further, in step A2, a second hole 4 into which the fastening member 5 is inserted is formed in the housing 1. As shown in FIG. 3(B), the second hole 4 is provided with a conical flange receiving surface 7 formed by expanding the diameter of the end on the first hole 3 side. In step A3, the first hole 3 and the second hole 4 are aligned using equipment (not shown) so that the coaxes of the first hole 3 and the second hole 4 are aligned, and the housing 1 and the end bell are aligned. 2 position is fixed.

In step A4, the burring punch 24 is inserted into the first hole 3 to perform burring. In this step, as shown in FIG. 2, the flange 6 is oriented inside the first hole 3 and inclined downward, and is in surface contact with the flange receiving surface 7. This prevents misalignment between the housing 1 and the end bell 2. In subsequent step A5, the fastening member 5 is inserted from the first hole 3 side, and the housing 1 and the end bell 2 are fastened and fixed.

[4. Action, effect]
(1) The above motor unit 10 is provided with a flange 6 that protrudes from the inner wall 21 of the first hole 3 toward the second hole 4 . By bringing this flange 6 into surface contact with the second hole 4, positional displacement (relative movement) of the housing 1 and end bell 2 after assembly can be prevented. Further, even if, for example, some external force acts on the end bell 2 while the motor 11 is operating, the end bell 2 can be prevented from moving relative to the housing 1. Thereby, it is possible to prevent a decrease in detection accuracy of the resolver 16 due to positional deviation. Therefore, according to the disclosed motor unit 10, detection accuracy of the resolver 16 can be ensured with a simple configuration, and deterioration of controllability of the motor 11 can be prevented.

(2) Further, the second hole portion 4 is provided with a flange receiving surface 7 that makes surface contact with the flange 6. By providing the flange receiving surface 7 in the second hole 4, the surface contact state of the flange 6 is stabilized, and displacement of the housing 1 and the end bell 2 after they are assembled is more reliably prevented. Therefore, it is possible to prevent the rotational positioning accuracy detected by the resolver 16 from deteriorating, and it is also possible to easily maintain the fixed state of the end bell 2, thereby further improving the controllability of the motor 11.

(3) As shown in FIG. 1, when the brake device 19 is installed on the end bell 2, by operating the brake device 19, torque in the rotor rotation direction acts on the end bell 2, and the end bell 2 There is a possibility that it will move slightly in the rotational direction. On the other hand, according to the motor unit 10 described above, such rotational movement of the end bell 2 can be restrained. In other words, even if the brake device 19 is activated, the end bell 2 can be prevented from shifting in the rotational direction with respect to the housing 1. Therefore, the detection accuracy of the resolver 16 can be improved with a simple configuration, and the controllability of the motor 11 can be further improved.

(4) In the motor unit 10 described above, the hardness of the material of the case having the second hole 4 can be set to be higher than the hardness of the material of the case having the first hole 3. For example, the material hardness of the housing 1 is preferably set to be higher than the material hardness of the end bell 2. With this configuration, when pressing the flange 6 of the first hole 3 against the second hole 4 with the burring punch 24, the flange 6 is bent with respect to the surface of the second hole 4 (flange receiving surface 7). It can be transformed. Thereby, the flange 6 can be reliably brought into surface contact with the second hole 4, and positioning accuracy can be improved.

(5) In the above motor unit 10, as shown in FIG. 2, the flange 6 is formed in a shape inclined with respect to the axis of the fastening member 5 in a cross section passing through the axis of the fastening member 5. With such a configuration, the tightening force acting between the housing 1 and the end bell 2 is easily distributed evenly between the flange 6 and the surface of the second hole 4 (flange receiving surface 7), and the The surface contact state can be further stabilized. Therefore, the detection accuracy of the resolver 16 can be maintained with a simple configuration, and the controllability of the motor 11 can also be maintained.

(6) In addition, in the method for manufacturing the motor unit 10 of this embodiment, as shown in FIG. 5, when assembling the housing 1 and the end bell 2, In this state, the burring punch 24 is inserted into the first hole 3. By employing such a method, the flange 6 can be reliably brought into surface contact with the second hole 4, and the housing 1 and the end bell 2 can be firmly positioned. Thereby, it is possible to prevent the accuracy of the resolver 16 from decreasing due to positional deviation, and the controllability of the motor 11 can be maintained.

[5. Variations]
The above-described embodiments are merely illustrative, and there is no intention to exclude the application of various modifications and techniques not specified in the present embodiments. Each configuration of this embodiment can be modified and implemented in various ways without departing from the spirit thereof. In addition, each configuration of this embodiment can be selected or selected as necessary, or can be appropriately combined with various configurations included in known techniques.

In the above embodiment, as shown in FIG. 2, the flange 6 is formed in a shape inclined with respect to the axis of the fastening member 5 in a cross section passing through the axis of the fastening member 5. The shape of the flange 6 after processing is not limited to this. For example, as shown in FIG. 6, the flange 6 may be formed in a shape parallel to the axis of the fastening member 5 in a cross section passing through the axis of the fastening member 5. In other words, the flange 6 may be bent and deformed until the contact surface between the flange 6 and the second hole 4 (flange receiving surface 7) becomes parallel to the axis of the fastening member 5. Even in such a configuration, it is possible to prevent positional displacement of the housing 1 and the end bell 2 after they are assembled.

Further, in the motor unit 10 shown in FIG. 1, the housing 1 is formed larger than the end bell 2, but this does not necessarily indicate a size relationship therebetween. The housing 1 only needs to have a size that accommodates at least the stator 12, and the end bell 2 only needs to have a size that accommodates at least the resolver 16. Regardless of the size relationship of each component, by adopting a structure in which the flange 6 of the first hole 3 is brought into surface contact with the second hole 4, the same effects as in the above embodiment can be obtained.

Further, in the above embodiment, the first hole 3 is formed in the end bell 2, and the second hole 4 is formed in the housing 1, but the relationship between these may be reversed. That is, the flange 6 may be formed on the housing 1 side, or a corresponding flange receiving surface 7 may be formed on the end bell 2 side. At least, by bringing the flange 6 protruding from the inner wall of the first hole 3 toward the second hole 4 into surface contact with the second hole 4, the same effect as in the above embodiment can be obtained. can.

Note that, as shown in FIG. 7, the end bell 2 may be a two-body object with a cover 32, and the resolver 16 may be arranged in a space surrounded by the end bell 2 and the cover 32. In this case, the brake device 19 may be arranged on the cover 32 instead of on the flat surface of the end bell 2. Alternatively, the housing 1 may be formed into a hollow cylindrical shape, and the bottom side thereof may be closed with the front bell 31. In this case, the top side of the housing 1 may be closed by the end bell 2, and the motor 11 may be disposed in a space surrounded by the housing 1, the end bell 2, and the front bell 31.

1 Housing 2 End bell 3 First hole 4 Second hole 5 Fastening member 6 Flange 7 Flange receiving surface 8 Hole wall 9 Thread 10 Motor unit 11 Motor (brushless motor)
12 Stator 13 Rotor 14 Shaft 15 Bearing 16 Resolver (rotation detection device)
17 Resolver stator 18 Resolver rotor 19 Brake device 21 Inner wall 22 Inner cylindrical surface 23 Conical surface 24 Burring punch 25 First cylindrical surface 26 Pressing surface 27 Second cylindrical surface 31 Front bell 32 Cover

Claims (8)

a housing in which a stator of a motor is fixed and a rotor of the motor is rotatably supported;
an end bell to which a rotation detection device is attached and joined to the housing via a fastening member;
a first hole formed in one of the housing and the end bell, into which the fastening member is inserted;
a second hole formed in the other of the housing and the end bell, into which the fastening member is inserted;
The first hole has a flange that protrudes from an inner wall of the first hole toward the second hole and comes into surface contact with the second hole at a joint surface of the housing and the end bell. A motor unit featuring: The motor unit according to claim 1, wherein the rotation detection device is a resolver. 3. The motor unit according to claim 1, wherein the second hole has a flange receiving surface that is expanded in diameter at an end on the first hole side and makes surface contact with the flange. The motor unit according to any one of claims 1 to 3, further comprising a brake device fixed to the end bell and restraining rotation of the rotor relative to the stator. The motor unit according to any one of claims 1 to 4, wherein the hardness of the material of the case having the second hole is greater than or equal to the hardness of the material of the case having the first hole. . The motor unit according to any one of claims 1 to 5, wherein the flange is formed in a shape that is inclined with respect to the axis in a cross section passing through the axis of the fastening member. The motor unit according to claim 1, wherein the flange is formed in a shape parallel to the axis in a cross section passing through the axis of the fastening member. A method for manufacturing a motor unit in which a housing in which a stator of a motor is fixed and a rotor of the motor is rotatably supported, and an end bell in which a rotation detection device is mounted are joined by a fastening member, the method comprising:
A first hole through which the fastening member is inserted, and a flange protruding from an inner wall of the first hole in a diametrical direction are formed in one of the housing and the end bell;
forming a second hole in the other of the housing and the end bell, into which the fastening member is inserted;
When assembling the housing and the end bell, in order to bring the flange into surface contact with the second hole, the first hole is aligned with the position of the first hole and the second hole. A method for manufacturing a motor unit, the method comprising inserting a burring punch into the section.

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