JP7415751B2 - Electric motor - Google Patents

Description

The present invention relates to an electric motor that includes two bearing houses and a conductive member that connects these bearing houses to each other.

Conventionally, as an electric motor, an inner rotor type electric motor is known in which a cylindrical rotor having a permanent magnet is disposed coaxially with the stator on the inner diameter side of a cylindrical stator that generates a rotating magnetic field. This electric motor is used, for example, to rotate a blower fan installed in an air conditioner.

When this electric motor is driven by a PWM type inverter that performs high frequency switching, a potential difference (shaft voltage) is generated between the inner ring and the outer ring of the bearing. When this shaft voltage reaches the dielectric breakdown voltage of the oil film inside the bearing, a current flows inside the bearing and causes electrical corrosion in the bearing. In order to prevent this electrolytic corrosion of the bearing, it is known that a bearing provided at one end of the motor in the direction of the rotating shaft and a bearing provided at the other end are electrically connected by a conductive member.
Patent Document 1 is cited as a conventional technique for fixing a conductive member to the outer circumferential surface of an outer shell of an electric motor. Furthermore, Patent Document 2 can be cited as a conventional technique for embedding a conductive member inside an electric motor.

Japanese Patent Application Publication No. 2007-20348 Japanese Patent Application Publication No. 2014-121100

Here, if the conductive member is fixed to the outer circumferential surface of the outer shell of the electric motor, the assemblability of the electric motor can be improved, but there is a risk that the conductive member will fall off from the outer circumferential surface. On the other hand, if the conductive member is embedded inside the motor, it is possible to prevent the conductive member from falling off from the motor, but the embedding process reduces the assemblability of the motor.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an electric motor that improves assemblability while preventing the conductive member from falling off the electric motor.

One aspect of the electric motor of the present invention includes a rotor, a shaft disposed along a rotation axis of the rotor and to which the rotor is fixed, a first bearing provided on one end side of the shaft, and a first bearing provided at one end of the shaft. It has a second bearing provided on the other end side of the shaft, an annular part, and end face parts formed at both ends of the annular part, and the above-mentioned part is provided inside the annular part and the end face part. The rotor includes an outer shell that accommodates a rotor, a conductive member that connects the first bearing and the second bearing, and legs that protrude radially outward from the outer peripheral surface of the outer shell. A mounting hole is formed in the leg portion to which the vibration isolating member is mounted. The mounting hole is provided with a fixing portion to which the conductive member is fixed.

According to the present invention, ease of assembly can be improved while preventing the conductive member from falling off the motor.

FIG. 1 is an overall perspective view of an electric motor according to the present invention. FIG. 1 is a cross-sectional view showing an electric motor according to the present invention. FIG. 2 is a perspective view of a bracket for an electric motor according to the present invention. FIG. 4 is an overall perspective view of the electric motor according to the present invention, with the bracket of FIG. 3 removed. FIG. 2 is a cross-sectional view showing a cross section along a cut groove in FIG. 1 . FIG. 2 is an overall perspective view of the electric motor according to the present invention, viewed from the output side, with the vibration isolating member and the conductive member removed. FIG. 7 is a perspective view of FIG. 6 with the vibration isolating member and the conductive portion attached. 6 is a perspective view of the conductive member of FIG. 5. FIG.

Next, one embodiment of the present invention will be described with reference to the drawings. In the description of the drawings below, the same or similar parts are designated by the same or similar symbols. However, it should be noted that the drawings are schematic and may differ from the reality. Therefore, specific components should be determined with reference to the following explanation.

In addition, the embodiments shown below exemplify devices and methods for embodying the technical idea of the present invention. It is not specific to the following. The technical idea of the present invention can be modified in various ways within the technical scope defined by the claims.

An electric motor according to an embodiment of the present invention will be described below.

<Overall configuration of electric motor>
1 to 5 are diagrams illustrating the configuration of the electric motor 1 in this embodiment. As shown in these figures, this electric motor 1 is, for example, a brushless DC motor. Although not shown, this electric motor 1 is used, for example, to rotationally drive a blower fan mounted on an outdoor unit of an air conditioner.

As shown in FIGS. 1 and 2, the electric motor 1 in this embodiment has a stator 2, a rotor 3, a motor outer shell (casing, outer shell) 10, a bracket 41, and conduction. A member 5 is provided.
In the following, an inner rotor type permanent magnet electric motor 1 is taken as an example, in which a cylindrical rotor 3 having a permanent magnet part 31 is rotatably arranged inside a cylindrical stator 2 that generates a rotating magnetic field in the radial direction. explain.

<Stator, rotor, and motor outer shell>
As shown in FIG. 2, the rotor 3 includes an annular permanent magnet part 31 and a connecting part 35 that is arranged on the inner diameter side of the permanent magnet part 31 and connects the permanent magnet part 31 and the shaft 32. Be prepared. The shaft 32 is arranged along the central axis of the cylindrical rotor 3 and is fixed to the rotor 3. In this embodiment, the permanent magnet part 31 and the connecting part 35 of the rotor 3 are formed by integral molding of a resin material mixed with ferrite magnetic material, and by magnetizing only the permanent magnet part 31 after molding. The permanent magnet portion 31 functions as a ferrite bond magnet. Moreover, the permanent magnet part 31 is magnetized so as to become a polar anisotropic magnet in which S poles and N poles appear alternately in the circumferential direction. This eliminates the need for a portion of the yoke for concentrating the flow of magnetic flux in the permanent magnet portion 31, and leakage magnetic flux can be suppressed.
Note that the permanent magnet portion 31 and the connecting portion 35 may be formed separately. For example, in the rotor 3, a plurality of sintered ferrite magnets (corresponding to the permanent magnet part 31) made by baking powdered ferrite magnetic material in a mold are attached to the outer peripheral surface of the rotor core (corresponding to the connecting part 35) in an annular shape. It may also be a so-called surface magnet (SPM) type rotor attached to the surface.

The stator 2 includes a stator core 21 having a cylindrical yoke (not shown) and a plurality of teeth (not shown) extending radially inward from the yoke, and a stator core 21 that is wound around the teeth through an insulator. It also includes a winding (not shown). This stator 2 is integrally molded with resin and is covered with a motor outer shell 10 (main body) made of resin, except for the inner circumferential surface of the stator core 21 (see FIGS. 2 and 4). That is, the motor outer shell 10 covers the stator 2 including the stator core 21 and the windings, and accommodates the rotor 3 therein. As shown in FIGS. 1 and 2, the stator 2 is arranged on the outer peripheral side of the rotor 3 (outside in the radial direction of the permanent magnet motor 1). Further, the stator core 21 of the stator 2 is arranged such that the teeth portion thereof are opposed to the permanent magnet portion 31 of the rotor 3 in the radial direction. In other words, the stator 2 is arranged such that the annular permanent magnet portion 31 of the rotor 3 faces the stator core 21 of the stator 2 in the radial direction.

The motor outer shell 10 serving as the main body may have any shape, but for example, the motor outer shell 10 may have an arbitrary shape. It is formed into a bottomed cylindrical shape with an opening O on the non-output side). In this embodiment, the motor outer shell 10 includes an annular portion 12, an opening O, and an end surface portion (bottom surface) 13 formed at the end opposite to the opening O (output side of the shaft 32). . Note that the motor outer shell 10 does not need to be entirely formed from an insulating material such as resin, and a portion may be formed from a metal that is a conductive material. Further, in this embodiment, the outer appearance of the motor outer shell 10 is cylindrical, but the outer appearance of the motor outer shell 10 may be a square prism or a hexagonal prism.

The rotor 3 is rotatably disposed on the inner peripheral side of the stator core 21 of the stator 2 with a predetermined gap therebetween. As shown in FIGS. 2, 4, and 5, the annularly arranged permanent magnet section 31 is arranged on the radially outer side (outer circumferential side) of the rotor 3 so as to face the stator core 21.

The rotor 3 is fixed around a shaft 32. The shaft 32 is rotatably supported (held) by a first bearing 33 and a second bearing 34 (bearing, bearing) fixed to the outer peripheral surface of the shaft 32. Further, the first bearing 33 is accommodated (held) in a first bearing accommodating portion 42 described later, and the second bearing 34 is accommodated (held) in a second bearing accommodating portion 43 described later, so that the rotor 3 rotates. freely supported. The first bearing accommodating portion 42 and the second bearing accommodating portion 43 are made of a magnetic material such as chromium-nickel stainless steel, for example.

<Bearing, bracket and bearing house section>
As shown in FIGS. 2, 3, and 5, the inner ring side of the first bearing 33 is fixed to one end side (non-output side) of the shaft 32. As shown in FIGS. The second bearing 34 has an inner ring side fixed to the other end side (output side) of the shaft 32. The first bearing 33 and the second bearing 34 (a pair of bearings) cooperate to rotatably support the shaft 32 and the rotor 3 connected to the shaft 32. For the first bearing 33 and the second bearing 34, for example, ball bearings are used.

The bracket 41 includes a first bearing accommodating portion 42 made of a magnetic material and accommodating the first bearing 33, and a nonmagnetic portion 44 (end surface portion) made of a nonmagnetic material (for example, resin). The bracket 41 is arranged in the motor outer shell 10 (main body part) of the permanent magnet electric motor 1 at one end in the direction of the rotation axis C, that is, on the opposite output side of the shaft 32. The non-magnetic part (end face part) 44 of the bracket 41 has a connecting part 45 connected to the first bearing accommodating part 42 (see FIGS. 2, 3, and 5). The non-magnetic part (end face part) 44 of the bracket 41 is molded integrally with the first bearing accommodating part 42, which is a magnetic part, by insert molding. The non-magnetic portion (end surface portion) 44 is connected to the first bearing accommodating portion 42 at a connecting portion 45 .
This bracket 41 serves as a lid that covers the opening O of the motor outer shell 10 (main body) and is attached by screwing to the end of the motor outer shell 10 (main body) on the non-output side. Note that the opening O of the motor outer shell 10 (main body) may be opened toward the output side. In this case, the bracket 41 is arranged on the output side of the shaft 32 rather than on the opposite output side of the shaft 32.

The non-magnetic portion 44 (end surface portion) of the bracket 41 is formed into a generally disk shape whose radial outer shape extends in the radial direction to the outer circumferential surface of the motor outer shell 10 . Further, the non-magnetic portion 44 (end surface portion) of the bracket 41 forms the resin outer shell of the permanent magnet motor 1 together with the motor outer shell 10 . The non-magnetic portion 44 includes a protrusion 410 that protrudes radially outward from the outer circumferential surface of the motor outer shell 10 when viewed from the direction of the rotation axis C. The protruding portion 410 comes into contact with a base end portion of a leg portion 107 of the motor outer shell 10, which will be described later. The protrusion 410 of the bracket 41 is arranged to overlap the leg 107 in the direction of the rotation axis C.

The protruding parts 410 of the bracket 41 are formed in the same number as the leg parts 107 provided on the motor outer shell 10 (three locations), and are formed, for example, in a trapezoidal shape when viewed from the direction of the rotation axis C. The portion has a screw hole portion 413 penetrating in the direction of the rotation axis C.

Note that the bracket 41 has a cut groove 416 formed on the outer surface side exposed to the outside of the permanent magnet motor 1 after assembly, in which a conductive member 5 for preventing electrolytic corrosion, which will be described later, is disposed (see FIG. 1). and 3).
This cut groove portion 416 extends radially outward from the center portion of the bracket 41 (cylindrical connection portion 45 of the non-magnetic portion 44 described later) to the outer circumferential surface of the bracket 41, and further extends from there into contact with the motor outer shell 10. It extends in the axial direction to the point where it touches.

After the bracket 41 is fitted to the motor outer shell 10 (main body part), the bracket 41 is screwed into the leg side fastening part (screw hole part) 103 (described later) of the leg part 107 of the motor outer shell 10 through the screw through hole part 413. (See Figure 1).
Further, a first bearing housing portion (bearing house portion) 42 for accommodating the first bearing 33 on the inside side (output side) of the permanent magnet motor 1 is arranged in the center of the disc-shaped bracket 41. There is. The first bearing accommodating portion 42 is generally formed into a bottomed cylindrical shape by, for example, press working. Furthermore, the non-magnetic portion 44 of the bracket 41 has a cylindrical connecting portion 45 connected to the first bearing accommodating portion 42 on the inner diameter side (see FIGS. 2 and 5).

A second bearing accommodating part (bearing house part) 43 for accommodating the second bearing 34 on the inner side (opposite the output side) of the electric motor 1 is arranged in the center of the output side end of the motor outer shell 10. (See Figures 2, 5 and 6). The second bearing accommodating part 43, like the first bearing accommodating part 42, is generally formed in a cylindrical shape with a bottom. The second bearing accommodating portion 43 is arranged inside (on the inner diameter side) of the annular permanent magnet portion 31 in the radial direction of the rotor 3 . The end surface portion 13 of the motor outer shell 10 has a connecting portion 14 connected to a flange portion 432 (described later) of the second bearing housing portion 43.

As shown in FIGS. 2 and 5, the first bearing accommodating portion 42 includes a cylindrical portion 421 that holds the outer ring side of the first bearing 33 from the radial direction, and an end portion of the cylindrical portion 421 in the rotation axis C direction. An annular flange portion 422 extending radially outward (outer circumferential side) in the rotor 3, and a crown portion extending radially inward (inner circumferential side) from the other end of the cylindrical portion 421 in the rotation axis C direction. 423. The crown portion 423 covers the other end side of the first bearing 33 in the rotation axis C direction. The outer peripheral edge of the annular flange portion 422 is located on the inner side (inner peripheral side) of the rotor 3 in the radial direction than the permanent magnet portion 31 . In other words, the first bearing housing portion 42 is formed so as not to overlap the permanent magnet portion 31 when viewed from the direction of the rotation axis C of the rotor 3 .

That is, the first bearing accommodating portion 42 (the bearing house portion included in the bracket 41) is arranged on the radially inner side (inner diameter side) of the rotor 3 than the permanent magnet portion 31 when viewed from the rotation axis C direction. Further, the outer peripheral edge (edge on the outer diameter side) of the flange portion 422 of the first bearing housing portion 42 (bearing house portion) is covered with resin, which is a non-magnetic material. The outer peripheral edge of the flange portion 422 of the one-bearing housing portion 42 is covered with a non-magnetic portion 44 made of resin.

As described above, the bracket 41 is formed of the first bearing housing part (magnetic part) 42, which is one of a pair of bearing housing parts (bearing house parts), and the non-magnetic part 44 (end surface part). Since the first bearing accommodating part (magnetic part) 42 is arranged on the inner diameter side of the permanent magnet part 31 in the radial direction of the rotor 3, the flange part 422 provided in the first bearing accommodating part 42 as a magnetic part is , it is possible to prevent the permanent magnet portion 31 from facing the permanent magnet portion 31 in the direction of the rotation axis C. Thereby, leakage magnetic flux flowing from the permanent magnet part 31 to the first bearing housing part (magnetic part) 42 can be suppressed. Further, in the first bearing housing portion (magnetic portion) 42 , the outer peripheral edge of the flange portion 422 adjacent to the permanent magnet portion 31 of the rotor 3 is covered with a non-magnetic portion 44 . Thereby, the path of leakage magnetic flux flowing from the permanent magnet part 31 to the first bearing housing part (bearing house part) 42 made of a magnetic material can be blocked by the non-magnetic part 44 made of a non-magnetic material. Therefore, leakage magnetic flux flowing from the permanent magnet section 31 to the first bearing housing section 42 can be further suppressed.

Note that this structure for suppressing magnetic flux leakage can be applied not only to the first bearing accommodating part 42 side but also to the second bearing accommodating part 43 side. At this time, the second bearing accommodating part 43 is formed in the same shape as the first bearing accommodating part 42, and includes a cylindrical part 431 that holds the outer ring side of the second bearing 34 from the radial direction, and a rotation of the cylindrical part 431. An annular flange portion 432 extending radially outward of the rotor 3 from one end in the axis C direction, and a crown portion 433 extending radially inward from the other end of the cylindrical portion 431 in the rotation axis C direction. , has. The second bearing accommodating portion 43 is arranged on the inner diameter side of the permanent magnet portion 31 in the radial direction of the rotor 3 . Further, the outer peripheral edge of the flange portion 422 included in the second bearing housing portion 43 is covered by the end surface portion 13 (connection portion 14) of the motor outer shell 10 made of resin, which is a non-magnetic material. Thereby, leakage magnetic flux flowing from the permanent magnet 31 to the second bearing housing portion 43 can be suppressed.

The non-magnetic part (end face part) 44 of the bracket 41 has a connecting part 45 connected to the first bearing housing part (bearing house part) 42 . The connecting portion 45 is formed into a generally cylindrical shape, and the flange portion 422 of the first bearing housing portion (bearing house portion) 42 is inserted into and fixed to the inner diameter side surface of the cylindrical connecting portion 45. . Here, the cylindrical part 421 of the first bearing housing part 42 is not in contact with the non-magnetic part 44 of the bracket 41 (not covered by the non-magnetic part 44), and only the outer peripheral edge of the flange part 422 are joined (connected) so as to be covered by the connecting portion 45 of the non-magnetic portion 44 . Further, an air gap AG1 is formed between the cylindrical portion 421 of the first bearing accommodating portion 42 and the cylindrical connecting portion 45 of the non-magnetic portion 44. Thereby, deformation of the motor outer shell 10 due to heat, impact, etc. becomes less likely to affect the first bearing 33. Furthermore, the contact area between the connecting part 45 of the bracket 41 and the flange part 422 of the first bearing housing part 42 can be reduced, and the heat generated in the windings wound around the stator core 21 can be reduced. 41 to the first bearing 33 can be suppressed. Thereby, the temperature rise of the first bearing 33 can be suppressed and deterioration of the first bearing 33 can be prevented.

In this embodiment, the second bearing housing part 43 side, which is the other of the pair of bearing housing parts (bearing house parts), has the same structure as the first bearing housing part 42 side. That is, the motor outer shell 10 is formed into a cylindrical shape with a bottom, and an annular portion 12 of the motor outer shell 10 that is integrated with the stator 2 and a radially inner (inner) The end face portion 13 of the motor outer shell 10 extends toward the circumferential side. The end surface portion 13 of the motor outer shell 10 has a cylindrical connecting portion 14 that is connected to the second bearing housing portion 43 . Similarly to the first bearing housing part 42, the second bearing housing part 43, which is the other of the pair of bearing housing parts, includes a cylindrical part 431 and a flange part 432 extending radially outward from the cylindrical part 431. Only the outer peripheral edge of the flange portion 432 is inserted into and fixed to the inner diameter side surface of the connecting portion 14 of the resin outer shell (motor outer shell 10). Furthermore, an air gap AG2 is formed between the cylindrical portion 431 of the second bearing accommodating portion 43 and the connecting portion 14 of the resin outer shell (motor outer shell 10).

Thereby, deformation of the motor outer shell 10 due to heat, shock, etc. becomes less likely to affect the second bearing 34. Furthermore, the contact area between the connecting portion 14 of the motor outer shell 10 and the flange portion 432 of the second bearing housing portion 43 can be reduced, and heat generation in the windings wound around the stator core 21 can be reduced. Transmission to the second bearing 34 via the resin outer shell 10 can be suppressed. Thereby, the temperature rise of the first bearing 33 can be suppressed and deterioration of the first bearing 33 can be prevented.

Further, as described above, the rotor 3 includes the connecting portion 35 to which the shaft 32 is fixed and connects the permanent magnet portion 31 and the shaft 32. The permanent magnet portion 31 is arranged to face the cylindrical stator core 21 in the radial direction. The connecting part 35 is arranged on the inner diameter side of the annularly arranged permanent magnet part 31. As shown in FIGS. 2 and 4, the connecting portion 35 has a recess 36 recessed in the axial direction of the rotation axis C (rotation axis C direction). The recessed portion 36 is formed such that the thickness of the connecting portion 35 in the rotational axis C direction at the position where the recessed portion 36 is formed is smaller than the thickness of the permanent magnet portion 31 in the rotational axis C direction. The flange portion 422 of the first bearing accommodating portion 42 is arranged to overlap with this recess 36 in the direction of the rotation axis C.

As a result, an annular recess 36 recessed toward the rotation axis C direction is formed in the rotor 3, and the flange portion 422 of the first bearing accommodating portion 42 can be disposed within this recess 36.
In this way, a part of the first bearing housing part 42 (flange part 422) can fit into the annular recess 36 recessed in the axial direction of the rotation axis C, and the thickness of the permanent magnet electric motor 1 in the rotation axis C direction can be reduced. This reduces the size of the permanent magnet motor 1 in the direction of the rotation axis C.

As shown in FIG. 4, the end of the stator 2 on the opposite output side in the direction of the rotation axis C (the upper end in FIG. 4) is electrically connected to a winding (not shown) of the stator core 21. Terminal pins 26 and bosses 27 that serve as guides when attaching a board (not shown) are provided.
The bracket 41 functions as an insulating cover to prevent the terminal pin 26 from being exposed to the outside of the permanent magnet motor 1.
In this embodiment, the terminal pins 26 are provided at three locations, and the bracket 41 is attached to the motor outer shell 10 so as to cover and hide these three locations.

The bracket 41 includes a cover body 414 attached along the upper end surface of the stator 2 and a fitting portion 415 integrally formed with the cover body 414. These cover main body 414 and fitting portion 415 correspond to the above-mentioned non-magnetic portion 44 (end surface portion).
The cover main body 414 is generally formed into a disk shape as a whole. As shown in FIG. 3, the fitting portion 415 is formed as an annular projection disposed on the outer peripheral edge of the cover body 414. As shown in FIG. 2, the fitting portion 415 is fitted to the non-output side end of the motor outer shell 10 (the upper end surface of the motor outer shell 10 in FIG. 4) from the rotation axis C direction, so that the motor outer shell 10 ( The main body portion) and the bracket 41 are aligned, and the first bearing 33 is accommodated in a first bearing accommodating portion 42 provided in the bracket 41.

<Characteristics of the invention>
The motor outer shell 10 (main body part) of the electric motor 1 has a diameter extending from the outer circumferential surface of the cylindrical motor outer shell 10 (the outer circumferential surface of the annular part 12) at one end side (the end on the non-output side) in the direction of the rotation axis C. It includes a plurality of legs 107 that protrude outward (on the outer diameter side) (see FIGS. 1, 2, 4 to 7). For example, three leg portions 107 are provided so as to be arranged at equal intervals in the circumferential direction of the electric motor 1.
The plurality of legs 107 protrude in a trapezoidal shape in the outer diameter direction of the electric motor 1 and have a predetermined thickness in the direction of the rotation axis C. Note that the number of legs 107 may be arbitrary, such as two or six, and the plurality of legs 107 may not be arranged at equal intervals.

As shown in FIGS. 1, 4, and 7, the trapezoid-shaped leg portion 107 has a circumferential length that becomes shorter toward the radially outer side (outer diameter side) of the electric motor 1. It is formed like this. Thereby, the strength of the leg portion 107 can be ensured, and a dead space, which will be described later, formed in the leg portion 107 can be effectively utilized.

Each of the plurality of legs 107 is formed with a leg side fastening part 103 and a vibration isolating member arrangement part 104 in which the vibration isolating member 6 is arranged. The vibration isolating member arrangement portion 104 is formed at the center of each leg portion 107 in the circumferential direction of the electric motor 1 .

The vibration isolating member 6 is exemplified by a vibration isolating rubber, a bush, etc. formed into a hollow bobbin shape or a cylindrical shape, for example. The vibration isolating member 6 of the embodiment is formed in a bobbin shape, and includes a core portion 61, flange portions 62 formed at both ends of the core portion 61 in the direction of the rotation axis C, and an insertion hole through which the fastening member is inserted. and a hole 63 (see FIGS. 5 and 7). Note that the bobbin-shaped vibration isolating member 6 may have a hexagonal shape or a quadrangular shape when viewed from the direction of the rotation axis C (shape when viewed from above). In the insertion hole 63 of the vibration isolating member 6, a fastening member (for example, a screw) (not shown) for attachment to an object to which the permanent magnet motor 1 is fixed (for example, the casing of an air conditioner) is inserted in the direction of the rotation axis C. It is inserted. The vibration isolating member 6 is made of an elastic material such as EPDM (ethylene propylene diene rubber) or CR (chloroprene rubber).

The leg-side fastening section 103 is, for example, a screw hole, an embedded nut, or the like, and a fastening member (such as a screw) (not shown) is fastened thereto. The leg side fastening part 103 formed on the leg part 107 and the screw hole part 413 formed on the bracket 41 are fastened together via the fastening member, so that the leg side fastening part 103 has a vibration-proof structure. It is fixed at a position that does not overlap with the member 6 (vibration isolating member arrangement portion 104). Thereby, it is possible to effectively utilize the area (dead space) in each leg 107 where the vibration isolating member 6 is not arranged, and therefore it is possible to suppress each leg 107 from increasing in size.

The vibration isolating member placement portion 104 formed on the leg portion 107 has a mounting hole 104A penetrating in the direction of the rotation axis C into which the center core 61 of the vibration isolating member 6 is fitted (attached), and a mounting hole 104A that penetrates in the direction of the rotation axis C. A cutout portion 104B is formed to connect the outer edge of the leg portion 107 and the attachment hole 104A in order to fit (attach) the vibration isolating member 6 from the outer diameter side. Thereby, the center portion 61 of the vibration isolating member 6 can be fitted into the mounting hole 104A via the notch portion 104B.
The vibration isolating member 6 attached to the vibration isolating member arrangement portion 104 is restricted from moving in the thickness direction of the leg portion 107 (in the direction of the rotation axis C) by the flange portion 62 provided on the vibration isolating member 6.

Note that the vibration isolation member placement portion 104 does not need to include the notch portion 104B that is connected to the outer peripheral edge of the leg portion 107, and may be a mounting hole 104A that is simply a through hole penetrating in the direction of the rotation axis C. . In this case, the vibration isolating member 6 is inserted into the mounting hole 104A formed as a through hole from the direction of the rotation axis C.

Even if the vibration isolating member arrangement portion 104 is formed with a recessed portion 106 in which one side of the leg portion 107 in the rotation axis C direction (the output side of the shaft 32) is recessed so as to match the shape of the vibration isolating member 6. good. Thereby, the shape of the vibration isolating member 6 can be simplified while ensuring the thickness of the leg portion 107 and maintaining its strength.

Here, when the electric motor 1 is driven by a PWM type inverter that performs high-frequency switching, the neutral point potential of the windings does not become zero, and a voltage called a common mode voltage is generated. Due to this common mode voltage, a potential difference (shaft voltage) is generated between the inner ring and the outer ring of each of the first bearing 33 and the second bearing 34 due to the stray capacitance inside the electric motor 1 . When this shaft voltage reaches the dielectric breakdown voltage of the oil film inside the bearing, a current flows inside the bearing and causes electrical corrosion in the bearing. The electric motor 1 of this embodiment includes a conductive member that connects the first bearing accommodating part 42 and the second bearing accommodating part 43 in which two bearings are housed, in order to prevent electrolytic corrosion from occurring in the bearings. 5.

The conductive member 5 is formed, for example, by processing a conductive material into a band shape or wire shape. In this embodiment, the conductive member 5 is formed by punching out a steel plate into a belt shape and bending it into a U-shape along the outer surfaces of the motor shell 10 and the bracket 41. (See Figures 5 and 8). The conduction member 5 connects the first bearing 33 and the second bearing by electrically connecting the first bearing accommodating part 42 in which the first bearing 33 is housed and the second bearing accommodating part 43 in which the second bearing 34 is housed. The potential on the outer ring side of each of the bearings 34 can be set to the same potential, and by reducing the potential difference between the inner and outer rings of each bearing, the occurrence of electrolytic corrosion can be suppressed.

The conductive member 5 includes a pair of connection ends 51, 51 connected to the bearing housing parts 42, 43, a pair of end face side arrangement parts 52, which are arranged to extend in the radial direction on the end face part of the outer shell of the electric motor 1, 52, and an outer circumferential surface side arrangement portion 53 disposed on the outer circumferential surface of the outer shell of the electric motor 1 along the direction of the rotation axis C. In this embodiment, the conductive member 5 is formed from one band-shaped member, but the conductive member 5 may be formed by connecting a plurality of conductive members.

As described above, in the electric motor 1 of the embodiment, cut grooves 108 and 416 are formed in the motor outer shell 10 and the bracket 41, respectively (see FIGS. 1, 5 to 7). By fitting the bracket 41 to the motor outer shell 10, the cut groove 416 of the bracket 41 and the cut groove 108 formed on the outer surface of the motor outer shell 10 are made continuous.

As shown in FIGS. 5 and 7, the conductive member 5 is formed on the outer surface of the electric motor 1 from the position of the flange portion 422 of the first bearing accommodating portion 42 to the notch groove portion 416 of the bracket 41 and the later-described notch groove portion 105 of the leg portion 107. , and the cut groove portion 108 of the motor outer shell 10, and extends to the position of the flange portion 432 of the second bearing housing portion 43. By disposing the conductive member 5 in each cut groove (416, 105, 108), the conductive member 5 does not protrude to the outer surface of the electric motor 1, and the conductive member 5 can be prevented from falling off from the electric motor 1.

Here, any one of the three legs 107 is provided with a cut groove (a conductive member fixing part ) 105 are formed. The cut groove 105 is a concave, V-shaped, etc. groove formed continuously with the mounting hole 104A so as to be depressed from the edge of the mounting hole 104A toward the inner diameter side.
Thereby, the edge of the attachment hole 104A serves as a guide for guiding the outer circumferential side arrangement portion 53 of the conductive member 5 to the cut groove portion 105, and positioning of the conductive member 5 becomes easy. In addition, by forming the cut groove portion 105 as a conductive member fixing portion in the leg portion 107 that protrudes from the outer periphery of the motor outer shell 10 in the outer radial direction, the groove is deeper than when the groove is directly provided on the side surface of the motor outer shell 10. This makes it more difficult for the conductive member 5 to fall off from the electric motor 1.

Further, as described above, the vibration isolating member arrangement section 104 includes a cutout section 104B in which a part of the leg section 107 is cut out so that the outer circumferential surface of the leg section 107 and the mounting hole 104A are continuous. . As a result, similarly to attaching the vibration isolating member 6 to the mounting hole 104A, the conductive member 5 is attached to the conductive member fixing portion provided in the mounting hole 104A from the outer peripheral side of the leg portion 107 via the notch 104B. It can be easily placed in the (cut groove) 105. That is, since the conductive member 5 is attached to the conductive member fixing portion 105 so as to extend from the outside of the electric motor 1, it is easy to attach the conductive member 5 to the electric motor 1.

Furthermore, before fitting the vibration isolating member 6 into the vibration isolating member arranging portion 104 (mounting hole 104A) of the leg portion 107, the outer circumferential surface side arranging portion 53 of the conductive member 5 is placed through the above-mentioned cut groove 105 in advance. Then, by fitting the vibration isolating member 6 into the vibration isolating member arrangement portion 104 (attachment hole 104A), the movement of the conductive member 5 in the outer radial direction is restricted by the vibration isolating member 6. Furthermore, movement of the conductive member 5 in the circumferential direction is restricted by a cut groove portion (conductive member fixing portion) 105 formed continuously in the mounting hole 104A. That is, the vibration isolating member 6 and the cut groove portion 105 cooperate to restrict the movement of the conductive member 5, thereby making it possible to prevent the conductive member 5 from falling off from the electric motor 1.

The connecting ends 51, 51, which are both ends of the conductive member 5, are arranged along the cylindrical connecting portions (45, 14) of the resin outer shell and the cylindrical portions (421, 431) of the bearing house portions (42, 43). After being bent, it is press-fitted and fixed into the outer gaps AG1 and AG2 of the cylindrical parts 421 and 431 of the bearing house parts 42 and 43 (see FIGS. 1, 5 to 7). Thereby, the conductive member 5 for preventing electrolytic corrosion can be easily fixed to the bearing houses 42 and 43 by using the gaps AG1 and AG2. By fixing the connecting ends 51, 51 of the conductive member 5 in contact with the flanges 422, 432 of the bearing house parts 42, 43, respectively, the first bearing 33 and the second bearing 34 are connected. Conducted.

Note that the means for fixing both ends of the conductive member 5 to the bearing house portion is not limited to the above-mentioned means. For example, the connecting ends 51, 51 of the conductive member 5 may be fixed to the bearing house parts 42, 43 by a caulking member (not shown).

Further, the conductive member 5 is not limited to the case where the whole is formed in a U-shape, and it is sufficient that the conductive member 5 is provided with an outer circumferential surface side arrangement portion 53 that is fixed to the mounting hole 104A formed in the leg portion 107. . For example, if the metal bearing house portion (the first bearing housing portion 42 and the second bearing housing portion 43) is formed to extend to the outer peripheral surface of the cylindrical motor outer shell 10, the conductive member 5 is connected to the motor. It is sufficient to include only the outer circumferential surface side arrangement portion 53 along the side surface of the outer shell 10 (the outer circumferential surface of the annular portion 12), and it is not necessary to provide the end surface side arrangement portion 52 along the end surface (end surface portions 13, 44) of the electric motor 1. good.

As described above, the electric motor 1 includes a rotor 3, a shaft 32 arranged along the rotation axis C of the rotor 3 and to which the rotor 3 is fixed, and a first bearing provided at one end of the shaft 32. 33, a second bearing 34 provided on the other end side of the shaft 32, an annular portion 12, and end face portions 13 and 44 formed at both ends of the annular portion 12 in the rotation axis C direction. Outer shells 10 and 41 that accommodate rotor 3 inside covered by section 12 and end face sections 13 and 44, conductive member 5 that conducts electrically between first bearing 33 and second bearing 34, and the outer peripheral surface of outer shell 10. The leg portion 107 is provided with a leg portion 107 that protrudes outward in the radial direction. A mounting hole 104A to which the vibration isolating member 6 is mounted is formed in the leg portion 107. A conductive member fixing portion (cut groove portion) 105 to which the conductive member 5 is fixed is provided in the mounting hole 104A.
As a result, the conductive member 5 can be fixed to the electric motor 1 using the cut groove portion (conductive member fixing portion) 105 provided in the mounting hole 104A, so that the conductive member 5 can be attached to the electric motor 1. This can be done easily, and the conductive member 5 can be prevented from falling off from the electric motor 1.

Note that the conductive member fixing portion 105 provided in the attachment hole A104 does not need to include a cut groove portion in which the edge of the attachment hole 104A is cut. At this time, the conductive member 5 is clamped and fixed between the edge of the circular attachment hole 104A and the vibration isolating member 6. In this case as well, the conductive member 5 can be easily fixed by using the mounting hole 104A and the vibration isolating member 6 attached to the mounting hole 104A, and the conductive member 5 can be prevented from falling off from the electric motor 1.

1...Electric motor 10...Motor outer shell (outer shell)
12... Annular part 13... End face part 104... Vibration isolating member placement part 104A... Mounting hole 104B... Notch part 105... Cut groove part (conducting member fixing part)
107... Leg part 2... Stator 3... Rotor 32... Shaft 33... First bearing 34... Second bearing 41... Bracket 44... End surface part 5... Conductive member 53... Outer peripheral surface side arrangement part 6... Vibration isolating member

Claims (5)

rotor and
a shaft arranged along the rotation axis of the rotor and to which the rotor is fixed;
a first bearing provided on one end side of the shaft;
a second bearing provided on the other end side of the shaft;
an annular portion; and end face portions formed at both ends of the annular portion in the direction of the rotation axis;
an outer shell that accommodates the rotor in an interior covered with the annular portion and the end surface portion;
a conduction member that connects the first bearing and the second bearing;
An electric motor comprising: legs projecting radially outward from the outer circumferential surface of the outer shell,
A mounting hole is formed in the leg to which a vibration isolating member is mounted,
The mounting hole is provided with a fixing part to which the conductive member is fixed ,
The conductive member is regulated from moving outward in the radial direction by the vibration isolating member attached to the mounting hole.
Electric motor. The electric motor according to claim 1,
The conductive member is arranged on the outer circumferential surface of the outer shell along the axial direction of the rotating shaft.
It has an outer peripheral surface side arrangement part,
In the electric motor, the conductive member has the outer peripheral surface side arrangement portion fixed to the fixing portion. The electric motor according to claim 1 or 2,
The fixing part is a groove part formed continuously in the mounting hole. The electric motor according to claim 3,
The fixed portion is formed in the mounting hole at a position where the distance from the rotating shaft is a minimum. The electric motor according to any one of claims 1 to 4,
A part of the outer diameter side of the mounting hole is cut out, and the outer peripheral surface of the leg portion and the mounting hole are continuous.

Images