JP7002359B2 - Rotating machine and bearing structure - Google Patents

Description

The present invention relates to a rotary electric machine and its bearing structure.

A rotary electric machine as a typical example of a rotary machine has a rotor and a stator. The rotor has a rotor shaft that extends axially and is rotatably supported at both ends by bearings, and a rotor core attached radially outward. The stator includes a stator core provided on the radial outer side of the rotor core and a stator having a stator winding that axially penetrates the radial inner portion thereof.

The rotor core and stator are usually housed in a frame. Both sides of the frame in the direction of the center axis of rotation are closed by bearing brackets. Each bearing is supported by a bearing bracket.

Bearings are roughly classified into plain bearings and pointed bearings. Generally, when used for a rotary electric machine that rotates at a high speed, a plain bearing is advantageous, and most of the rotary electric machines use a plain bearing.

When the induction motor is operated by PWM (Pulse Width Modulation), the neutral point voltage does not become zero and the common mode voltage remains. As a result, a potential difference is generated between the rotor shaft and the ground.

In addition, the shaft voltage of the generator is the imbalance of the cross-chain magnetic flux of the shaft due to the non-uniform magnetic resistance of the stator core, the electrostatic action due to the accumulation of static charge, and the potential between the shaft and the bearing due to the grounding of the rotor winding. This is due to the occurrence of.

In a state where such a shaft voltage is generated, when the oil film of the bearing is cut off, a shaft current flows in the path including the rotor shaft and the bearing. At this time, an arc flows between the shaft and the bearing, causing a melting phenomenon in the metal of the rotating portion and the stationary portion of the bearing. This melting phenomenon causes scratches called pitting on the metal portion and scoring on the shaft in the slide bearing. Further, in a rolling bearing, it appears as a ridge mark (Ridgemark).

Further, when an axial current is generated, there is a concern that the bearing may overheat and burn out. Alternatively, there is a problem of corrosion on the contact surface between the rotor shaft and the bearing, a problem of generation of abnormal noise, and the like.

As a countermeasure for this, regardless of whether it is a plain bearing or a rolling bearing, an insulator is inserted between the bearing and its mounting base to prevent the generation of axial current (see Patent Documents 1 and 2). That is, an insulating member, which is an electrical insulator, is provided, for example, in a state of being sandwiched between the bearing metal and the housing.

Japanese Unexamined Patent Publication No. 2000-245100 Japanese Unexamined Patent Publication No. 2008-148453

FIG. 5 is an axial upper half vertical cross-sectional view showing a configuration example of a conventional bearing structure 30 of a rotary electric machine. Further, FIG. 6 is a partial vertical sectional view centering on a portion A of FIG. 5 for explaining the insulating member and its fitting. 5 and 6 show the case of a plain bearing.

As shown in FIG. 5, conventionally, the insulating member 33 is attached to the bearing body 31. The radial outer surface of the insulating member 33 is formed so as to be in close contact with the inner surface of the housing 32.

As shown in FIGS. 5 and 6, hereinafter, the direction in which the rotation center axis of the rotor shaft 11 extends is referred to as the z direction, and the direction from the rotation center axis to the outside in the radial direction is referred to as the r direction.

As shown in FIG. 6, a plurality of receiving grooves 31a extending in the circumferential direction are formed on the outer surface of the bearing body 31 in the radial direction. Each receiving groove 31a extends so as to pierce the bearing body 31 in the z direction.

The insulating member 33 has a planar portion 33a that covers the radial outer surface of the bearing body 31, and a protruding portion 33b that fixes the planar portion 33a to the bearing body 31. The protruding portion 33b finally has the same shape as the space in the receiving groove 31a.

In such a conventional bearing structure, many steps are required, such as forming the receiving groove 31a, fitting the insulating member 33, and molding until the final assembled state thereafter, which is more concise. The configuration and method were desired.

Therefore, an object of the present invention is to realize electrical insulation of bearings in a rotary electric machine with a simple structure.

In order to achieve the above object, the present invention has a rotor shaft extending in the direction of the center axis of rotation, a rotor having a rotor core attached to the radial outer side of the rotor shaft, and a diameter of the rotor core. The rotor shaft is statically supported by a stator having a cylindrical stator core provided on the outer side in the direction and a plurality of stator windings penetrating the stator core in the direction of the rotation center axis. A rotary electric machine including two bearing structures rotatably supported on both sides of the rotor core, each of the two bearing structures arranged radially outside the rotor shaft. A bearing body that is slidably contacted with the rotor shaft and receives a reaction force from the rotor shaft, a housing that is provided on the radial outer side of the bearing body and supports the bearing body, and is attached to the inner surface of the housing. An insulating member having a planar portion covering a portion of the housing facing the bearing body and a protruding portion protruding only radially outward from the planar portion and extending in a ring shape in the circumferential direction of the inner surface of the housing. However, the housing is formed with a bearing groove that fits with the protrusion, the cross-sectional shape of the protrusion is rectangular, and the height is longer than the length in the axial direction .

Further, in the present invention, the rotor shaft extending in the direction of the center axis of rotation, the rotor having the rotor core, the stator, and the rotor shaft of the rotary electric machine provided with the rotor shaft are sandwiched. A bearing structure that rotatably supports the rotor shaft on both sides, and is a bearing body that is arranged on the radial outer side of the rotor shaft and is slidably contacted with the rotor shaft to receive a reaction force from the rotor shaft. A housing provided on the radial outer side of the bearing body to support the bearing body, a planar portion attached to the inner surface of the housing and covering a portion of the housing facing the bearing body, and a surface thereof. It is provided with an insulating member having a protruding portion extending only radially outward from the shaped portion and extending in a ring shape in the circumferential direction of the inner surface of the housing, and the housing is formed with a bearing groove that fits with the protruding portion. The cross-sectional shape of the protruding portion is rectangular, and the height is longer than the axial length.

According to the present invention, it is possible to realize electrical insulation of a bearing in a rotary electric machine with a simple structure.

It is a vertical sectional view which shows the structure of the rotary electric machine which concerns on this embodiment. It is the upper half vertical sectional view in the axial direction which shows the structure of the bearing structure of the rotary electric machine which concerns on this embodiment. It is a partial vertical sectional view showing mainly the part B of FIG. 2 for explaining the insulating member of the bearing structure of the rotary electric machine which concerns on this embodiment, and the fitting thereof. It is a flow diagram which shows the procedure of the attachment method of the insulating member of the bearing structure of the rotary electric machine which concerns on this embodiment. It is the upper half vertical sectional view in the axial direction which shows the structural example of the conventional bearing structure of a rotary electric machine. It is a partial vertical cross-sectional view which shows mainly the part A of FIG. 5 for demonstrating the insulating member and the fitting thereof in the structural example of the conventional bearing structure of a rotary electric machine. It is a flow diagram which shows the procedure of the attachment method of the insulating member in the structural example of the conventional bearing structure of a rotary electric machine.

Hereinafter, the rotary electric machine and the bearing structure thereof according to the present invention will be described with reference to the drawings. Here, common reference numerals are given to parts that are the same as or similar to each other, and duplicate description is omitted.

FIG. 1 is a vertical sectional view showing a configuration of a rotary electric machine according to the present embodiment. The rotary electric machine 200 has a rotor 10, a stator 20, two bearing structures 100, a frame 40, and two bearing brackets 45.

The rotor 10 has a rotor shaft 11 extending in the rotation center axial direction (axial direction), and a rotor core 12 attached to the radial outer side of the rotor shaft 11. Hereinafter, the axial direction of the rotor shaft 11 is referred to as the z direction, and the direction extending radially from the rotation center axis is referred to as the r direction.

The stator 20 has a cylindrical stator core 21 arranged radially outside the rotor core 12, and a plurality of stator windings 22 that axially penetrate the stator core 21. The stator winding 22 is housed in a plurality of stator slots (not shown) formed near the radial inner surface of the stator core 21 and extending in the z direction at intervals in the circumferential direction. It extends in the direction.

Each of the two bearing structures 100 rotatably supports both sides of the rotor shaft 11 in the axial direction.

The frame 40 is arranged radially outside the stator 20 to accommodate the rotor core 12 and the stator 20. Both ends of the frame 40 in the axial direction are closed by bearing brackets 45, respectively. Each bearing bracket 45 statically supports each bearing structure 100.

FIG. 2 is an axial upper half vertical cross-sectional view showing the configuration of the bearing structure of the rotary electric machine according to the present embodiment. The bearing structure 100 includes a bearing body 110 and a housing 120. The bearing structure 100 in FIG. 2 shows the case of a plain bearing.

The bearing body 110 surrounds the radial outer side of the rotor shaft 11 in the circumferential direction, and is formed in a shape such that the inner surface is in contact with the rotor shaft 11. The bearing body 110 is configured to be divisible into two parts (not shown), for example. The two portions are attached so as to surround the rotor shaft 11 from both sides in the radial direction of the rotor shaft 11, and then are connected and integrated by, for example, screws or the like. The integrated bearing body 110 has a shape of a rotating body centered on a rotation center axis.

The contact surface of the inner surface of the bearing body 110 with the rotor shaft 11 is slidably in contact with the rotor shaft 11 in a state where the rotor shaft 11 is rotating, and becomes a sliding surface with the rotor shaft 11. The bearing body 110 has a sliding member 111 extending along the sliding surface. The material of the sliding member 111 is different from the material of the main body 112 other than the sliding member 111 of the bearing main body 110. The material of the sliding member 111 is, for example, an alloy for a slide bearing (hereinafter, referred to as white metal) mainly composed of a low melting point alloy such as lead, tin, antimony, and zinc. Other than the sliding member, a structural material, that is, a steel material having structural strength, a carbon material, or the like can be used.

The bearing body 110 comes into contact with the rotor shaft 11 at the sliding member 111 and receives a reaction force from the rotor shaft 11. The radial outer side of the bearing body 110 has a shape in which the diameter decreases toward both sides in the axial direction. Has been done. At least one lubrication hole 113 penetrating in the radial direction is formed in the central portion of the bearing body 110 in the axial direction.

The housing 120 supports the bearing body 110 against the reaction force from the rotor shaft 11 received by the bearing body 110. The housing 120 is supported by a bearing bracket 45 (FIG. 1). The housing 120 may be formed so as to coincide with the bearing bracket 45.

The radial inner surface of the housing 120 is formed so as to face the shape of the outer surface of the bearing body 110. Since the bearing body 110 has a rotating body shape centered on the axis of rotation, the radial inner side surface of the housing 120 also has a rotationally symmetric shape. As the housing 120, a steel material, a carbon material, or the like can be used as the structural material.

At a position corresponding to the central position in the axial direction of the bearing body 110, a recess 121 as a passage for lubricating oil is formed on the inner surface of the housing 120 over the circumferential direction. Further, a refueling hole 123 is formed so as to communicate with the recessed portion 121 from the outside.

An insulating member 130 is provided between the bearing body 110 and the housing 120, and extends in a curved surface. The insulating member 130 electrically insulates between the bearing body 110 and the housing 120. The insulating member 130 has a planar portion 131 and a protruding portion 132. The material of the insulating member 130 is, for example, an insulating material such as silicon rubber or epoxy resin.

The radial inner surface of the housing 120 is formed so as to be in close contact with the radial outer surface of the bearing body 110. The bearing body 110 and the housing 120 are in close contact with each other via the planar portion 131 of the insulating member 130. The housing 120 is also configured to be divisible into two parts (not shown), for example, after the two parts are attached so as to surround the bearing body 110 from both sides in the vertical direction of the bearing body 110, for example, a screw or the like. Assembled together.

FIG. 3 is a partial vertical cross-sectional view centering on a portion B of FIG. 2 for explaining an insulating member of the bearing structure of the rotary electric machine according to the present embodiment and its fitting. Only one is shown in the axial direction, but the other is also formed plane-symmetrically.

The planar portion 131 is attached so as to cover the radial inner surface of the housing 120. In the planar portion 131, an opening 133 is formed in a portion corresponding to the oil supply hole 113 of the bearing main body 110.

The protrusion 132 fixes the planar portion 131 to the housing 120. The protrusions 132 are formed at intervals in the axial direction. Each of the plurality of projecting portions 132 projects in the r direction from the outer surface of the planar portion 131. That is, the protruding portion side surface 132a extending from the outer surface of the planar portion 131 is in a plane perpendicular to the rotation axis CL. Further, the protruding portion 132 is formed so as to extend in a ring shape along the circumferential direction.

A plurality of receiving grooves 124 that fit with the protruding portion 132 of the insulating member 130 are formed inside the housing 120 in the radial direction. Since the protruding portion 132 protrudes in the r direction, the receiving groove 124 is also formed so as to be deep in the r direction. That is, the receiving groove side surface 124a of the receiving groove 124 is in a plane perpendicular to the rotation axis CL.

The insulating member 130 is similarly divided according to the divided form of the housing 120. Each of the divided insulating members 130 is attached to each of the divided housings 120 and then coupled and integrated with each other. In the following description, the description of the parts related to the division and the integration after each installation will be omitted.

In addition, in FIG. 3, the number of each of the protrusion 132 of the insulating member 130 and the receiving groove 124 of the housing 120 corresponding thereto is shown as an example in the case where two are formed on one side, that is, four in total. However, it is not limited to this. There may be two cases on one side, that is, two cases in total. Alternatively, there may be three or more cases each. It may be appropriately set from the shape of the curved surface inside the radial direction of the housing 120, the size of the transmitted load, the manufacturability, and the like.

FIG. 4 is a flow chart showing a procedure of a method of attaching an insulating member of a bearing structure of a rotary electric machine according to the present embodiment.

First, the insulating member 130 is molded (step S11). When the housing 120 is divided into upper and lower parts, the insulating member 130 separately forms a portion that fits into the upper portion and a portion that fits into the lower portion.

Next to step S11, the receiving groove 124 of the housing 120 is formed (step S12). The radial inner surface of the housing 120 has a rotating body surface shape centered on the axis of rotation. Further, the receiving groove 124 is formed so as to be deep in the r direction. Therefore, forming the receiving groove 124 on the radial inner surface of the housing 120 can be easily performed using a lathe. Here, when forming the receiving groove 124, cutting may be performed with the upper and lower housings 120 integrated.

Note that step S12 may be performed in parallel with step S11 without being performed after step S11.

After step S11 and step S12, the protrusion 132 of the insulating member 130 is fitted into the receiving groove 124 formed on the radial inner surface of the housing 120 (step S13). At this time, each of the divided elements of the housing 120, for example, when it is divided into upper and lower parts, each of the upper half and the lower half of the housing 120, and the upper half and the lower half of the insulating member 130, respectively. To fit. Since the receiving groove 124 and the protruding portion 132 are each formed in the r direction, the insulating member 130 is inserted so that the direction of the insulating member 130 is parallel to the protruding portion side surface 132a and the receiving groove side surface 124a. This is possible by moving the insulating member 130 in one direction in the r direction, and can be easily performed.

After that, in the assembly process of the rotary electric machine 200, each member of the bearing structure 100 is sequentially attached.

FIG. 7 is a flow chart showing a procedure of a method of attaching an insulating member in a configuration example of a conventional bearing structure.

First, the insulating member 33 is molded (step S01). At this time, molding is performed so as to have the planar portion 33a and the protruding portion 33b.

Next to step S01, a receiving groove 31a is formed in the bearing body 31 (step S02). The bearing body 31 is rotationally symmetric about the rotation axis CL. Therefore, the cutting of the entire bearing body 31 is such that the distance in the r direction is changed while moving in the z direction. On the other hand, the receiving groove 31a is a groove extending in the z direction. Therefore, when forming the receiving groove 31a, the configuration at the time of cutting needs to be in a completely different state.

After step S01 and step S02, the protruding portion 33b of the insulating member 33 is fitted into the receiving groove 31a formed in the bearing body 31 (step S03). The insulating member 33 will be inserted in the z direction.

Next, the insulating member 33 is heated in a state where the protruding portion 33b of the insulating member 33 and the receiving groove 31a are fitted to each other (step S04). When the insulating member 33 becomes deformable by heating, the insulating member 33 is pressed from the inside in the radial direction (step S05). By pressing, the protruding portion 33b of the insulating member 33 penetrates deep into the receiving groove 31a. As a result, even when the insulating member 33 returns to room temperature, the protruding portion 33b completely fills the space in the receiving groove 31a.

Next, with the insulating member 33 attached to the outer surface of the bearing body 31, the outer surface is finished (step S06). This is because the surface shape of the insulating member 33 is deformed by the processing in steps S04 and S05.

As described above, in the bearing structure 30 of the conventional example, as shown in FIG. 6, the protrusions 33b on both sides of the center of the insulating member 33 in the z direction face each other toward the center in the z direction, and are insulated. After the member 33 is completely molded, it is difficult to attach the member 33 to the outside of the bearing body 31 in the radial direction. Therefore, in the bearing structure 30 of the conventional example, it is necessary to take a complicated procedure in order to form the insulating member 33.

On the other hand, in the present embodiment, as described above, the shape is as shown in FIG. 3, and as shown in FIG. 4, after the insulating member 130 is formed into the final shape, the receiving groove 124 of the housing 120 is formed. It can be attached to. Therefore, the procedure is simpler than that of the bearing structure 30 of the conventional example. Therefore, according to the present embodiment, there is provided a bearing structure 100 capable of realizing electrical insulation in a rotary electric machine 200 by a simpler configuration and an easier and more reliable method, and a rotary electric machine 200 having the bearing structure 100. can do.

[Other embodiments]
Although the embodiments of the present invention have been described above, the embodiments are presented as examples and are not intended to limit the scope of the invention. For example, in the embodiment, when the rotary electric machine has a frame and a bearing bracket, a case where the housing is supported by the bearing bracket or the housing is integrally formed with the bearing bracket is shown as an example. However, it is not limited to this. For example, there may be a case where the rotary electric machine does not have a frame and a bearing bracket, and the bearing structure is directly statically supported from the outside.

Further, in the embodiment, the case where the radial outer surface of the bearing body 110 and the radial inner surface of the housing 120 are rotationally symmetric with respect to the axis of rotation is shown, but the present invention is not limited to this. For example, the cross section perpendicular to the axial direction may be a polygon instead of a circle.

Further, the embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. The embodiments and variations thereof are included in the scope of the invention described in the claims and the equivalent scope thereof, as are included in the scope and gist of the invention.

10 ... Rotor, 11 ... Rotor shaft, 12 ... Rotor core, 20 ... Stator, 21 ... Stator winding, 22 ... Stator winding, 30 ... Bearing structure, 31 ... Bearing body, 31a ... Receiving groove, 32 ... Housing, 33 ... Insulation member, 33a ... Planar portion, 33b ... Projection, 40 ... Frame, 45 ... Bearing bracket, 100 ... Bearing structure, 110 ... Bearing body, 111 ... Sliding member, 112 ... Main body, 113 ... Refueling hole, 120 ... Housing, 121 ... Recessed portion, 122 ... Fixing groove, 123 ... Refueling hole, 124 ... Bearing groove, 124a ... Bearing groove side surface, 130 ... Insulating member, 131 ... Planed portion, 132 ... Projecting portion , 132a ... Protruding side surface, 133 ... Opening, 200 ... Rotating electric machine

Claims (3)

A rotor having a rotor shaft extending in the direction of the center axis of rotation and a rotor core attached to the radial outer side of the rotor shaft.
A stator having a cylindrical stator core provided on the radial outer side of the rotor core, and a plurality of stator windings penetrating the stator core in the direction of the center axis of rotation.
Two bearing structures that are statically supported and rotatably support the rotor shaft on both sides of the rotor core.
It is a rotary electric machine equipped with
Each of the two bearing structures
A bearing body that is arranged on the radial outer side of the rotor shaft and is slidably in contact with the rotor shaft to receive a reaction force from the rotor shaft.
A housing provided on the radial outer side of the bearing body to support the bearing body, and a housing.
A planar portion attached to the inner surface of the housing and covering a portion of the housing facing the bearing body, and a protrusion extending radially outward from the planar portion and extending in a ring shape in the circumferential direction of the inner surface of the housing. It is provided with an insulating member having a portion and
The housing is formed with a receiving groove that fits with the protrusion.
The cross-sectional shape of the protrusion is rectangular, and the height is longer than the axial length.
A rotating electric machine characterized by that. The rotary electric machine according to claim 1, wherein the radial outer surface of the bearing body and the radial inner surface of the housing facing the same have a rotationally symmetric shape. The rotor shaft extending in the direction of the center axis of rotation, the rotor having a rotor core, the stator, and the rotor on both sides of the rotor core of the rotary electric machine provided with the rotor shaft, which are statically supported. It is a bearing structure that rotatably supports the shaft.
A bearing body that is arranged on the radial outer side of the rotor shaft and is slidably in contact with the rotor shaft to receive a reaction force from the rotor shaft.
A housing provided on the radial outer side of the bearing body to support the bearing body, and a housing.
A planar portion attached to the inner surface of the housing and covering a portion of the housing facing the bearing body, and a protrusion extending radially outward from the planar portion and extending in a ring shape in the circumferential direction of the inner surface of the housing. It is provided with an insulating member having a portion and
The housing is formed with a receiving groove that fits with the protrusion.
The cross-sectional shape of the protrusion is rectangular, and the height is longer than the axial length.
The bearing structure is characterized by that.

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