CN105720749B

CN105720749B - Rotating electrical machine

Info

Publication number: CN105720749B
Application number: CN201510951804.4A
Authority: CN
Inventors: 中村裕; 丸本达也
Original assignee: Toshiba Mitsubishi Electric Industrial Systems Corp
Current assignee: Toshiba Mitsubishi Electric Industrial Systems Corp
Priority date: 2014-12-17
Filing date: 2015-12-16
Publication date: 2020-02-21
Anticipated expiration: 2035-12-16
Also published as: JP6121980B2; JP2016116407A; CN105720749A

Abstract

The invention improves the operability of replacement operation of a grounding brush in a rotating electrical machine. A rotating electric machine (100) is provided with: a rotor (10) having a rotating shaft (11) and a rotor core (12); a stator (20) having a stator core (21) and a stator coil (22); and grounding means (38, 40) for preventing static electricity from accumulating in the rotor (10). The grounding device (38, 40) comprises: a grounding brush which is fixed to the rotating shaft (11) in a stationary manner in a press-fit state; a support bracket for supporting the grounding brush in a pressure-contact state on the rotating shaft (11); a brush pressing member rotatably supported by the support bracket and pressing the ground brush so that the ground brush is pressed against the rotating shaft (11); and a drive support part (44) formed to enable the support bracket to move between the installation position and the radial outer side.

Description

Rotating electrical machine

Technical Field

The present invention relates to a rotating electric machine having a grounding brush.

Background

A voltage called a shaft voltage is generated between a shaft end surface and a bearing in a rotor shaft of a rotating electrical machine. The causes of the axial voltage include an electromagnetic induction action, an electrostatic induction action, and an accumulation of static charge, which are caused by magnetomotive force and unbalance of a magnetic circuit.

Even when the inverter is driven by a sine wave power supply, the above-described action and the capacitance of the rotating electric machine generate a slight shaft voltage, but the inverter tends to be influenced by a high frequency component and increase in voltage compared to the sine wave power supply.

In a rotating electrical machine, a shaft voltage is high, and a current flows due to discharge or energization through an oil film or a grease film, which has an influence on damage to a shaft or a bearing.

Therefore, in a rotating electrical machine in which a situation in which the shaft voltage is high is likely to occur, a grounding device is provided in the vicinity of either one of the two bearings. The grounding device comprises: a grounding brush for statically supporting the grounding brush to make the grounding brush contact with the rotating shaft; and a holding portion that is statically supported and that brings the grounding brush into pressure contact with the rotating shaft (patent document 1). The holding part is held by the bracket, and the following measures are implemented: the current is reduced to the bearing bracket (ground) so that no current flows through the bearing.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. Sho 63-97358

Disclosure of Invention

Problems to be solved by the invention

Since the grounding brush is kept in pressure contact with the rotating shaft, abrasion occurs. Therefore, when a predetermined amount of wear is reached, replacement is necessary.

In the case of a rotating electrical machine having an outer fan, a grounding device provided near a bearing on the side close to the outer fan is provided in a space between a frame and an outer fan cover. Therefore, an opening for taking out and inserting the grounding brush into and out of the grounding device is formed in the outer fan cover.

Therefore, when the grounding brush is replaced, the grounding brush is removed through the removal/insertion opening, and a replacement grounding brush is inserted. The grounding brush is removed and attached by inserting a hand into the removal/insertion opening. Therefore, there is a possibility that the operability is deteriorated and the hand may be injured depending on the case, and there is a problem that the operability needs to be improved.

Therefore, an object of the present invention is to improve the operability of the replacement operation of the grounding brush in the rotating electric machine.

Means for solving the problems

In order to achieve the above object, a rotating electrical machine according to the present invention includes: a rotor having a rotating shaft rotatably supported by a shaft, extending in an axial direction at a center of the rotating shaft, and a rotor core provided outside the rotating shaft; a stator having a stator core disposed radially outward of the rotating shaft and a stator coil provided in a slot formed in the stator core; and a grounding device for preventing static electricity from accumulating in the rotor, the grounding device including: a grounding brush which is statically fixed to the rotating shaft in a pressure-welded state; a support bracket that statically supports the grounding brush in a press-contact state with the rotating shaft; a brush presser rotatably supported by the support bracket and pressing the grounding brush so that the grounding brush is pressed against the rotating shaft; and a drive support portion configured to enable the support frame to move between a mounting location and the radially outer side.

Effects of the invention

According to the present invention, the operability of the replacement operation of the grounding brush can be improved in the rotating electric machine.

Drawings

Fig. 1 is a longitudinal sectional view of a rotary electric machine according to an embodiment.

Fig. 2 is a partial longitudinal cross-sectional view showing a portion of the grounding device as seen along line II-II of fig. 1.

Fig. 3 is a partial transverse cross-sectional view showing a portion of the grounding device as viewed along line III-III of fig. 2.

Fig. 4 is a conceptual diagram for explaining the structure and operation of the drive support portion of the grounding device of the rotating electric machine according to the embodiment.

Detailed Description

Hereinafter, a squirrel cage induction motor according to an embodiment of the present invention will be described with reference to the drawings.

Fig. 1 is a longitudinal sectional view of a rotary electric machine according to an embodiment. The rotating electric machine 100 includes a rotor 10, a stator 20, a frame 31, an outer fan side bearing 32, a coupling side bearing 33, an outer fan 35, and an outer fan cover 37.

The rotor 10 includes a rotating shaft 11, a rotor core 12, a rotor rod 13, and a short ring 14. The rotating shaft 11 is supported rotatably about the main shaft and extends in the main shaft direction. The rotor core 12 has a central opening formed in the center thereof and penetrating the rotating shaft 11, and is formed in a cylindrical shape, for example, by laminating ferromagnetic silicon steel plates in the main shaft direction. Further, through holes, not shown, are formed in the rotor core 12 at intervals in the circumferential direction on the radially outer side of the central opening, that is, in the vicinity of the radially outer side of the rotor core 12.

The rotor rods 13 are conductive bodies and are provided in the respective through holes. The short ring 14 is an annular conductor that protrudes from both ends of the rotor core 12 in the axial direction and electrically connects the rotor bars 13 to each other.

The stator 20 includes a stator core 21 and a stator coil 22. The stator core 21 is mainly made of a ferromagnetic material, is provided radially outside the rotor core 12, and faces the rotor core 12 with a gap. The stator coil 22 has a conductor housed in a not-shown groove formed in the stator core 21 and extending in the main shaft direction, and a connection portion outside the stator core 21.

The frame 31 houses the rotor core 12 and the stator 20. The outer fan side bearing 32 and the coupling side bearing 33 on the coupling 11a side as a coupling part to be coupled to a rotation mechanism not shown rotatably support both sides of the shaft 11 in the main shaft direction. The outer fan side bearing 32 and the coupling side bearing 33 are respectively fixed by the frame 31.

An outer fan 35 is mounted axially outward of the portion of the shaft 11 supported by the outer fan-side bearing 32. In addition, a part of the frame 31 and the outer fan 35 are covered with an outer fan cover 37. A cooling atmosphere suction port 37b is formed in a part of the outer fan cover 37 on the suction side of the outer fan 35. The outer fan cover 37 is provided with a treatment opening 37a for treating a grounding brush of a support bracket 43 (fig. 2 and 3) described later, and is covered with a cover except for treatment.

A coupling-side grounding device 38 is provided between the coupling-side bearing 33 and the coupling portion 11 a. Further, an outer fan side grounding device 40 is provided between the outer fan 35 and the outer fan side bearing 32. The outer fan-side grounding device 40 has a drive support 44. The driving support portion 44 will be described below with reference to fig. 2.

Fig. 2 is a partial longitudinal cross-sectional view showing a portion of the grounding device as seen along line II-II of fig. 1. Fig. 3 is a partial transverse cross-sectional view showing a portion of the grounding device viewed along line III-III of fig. 2. The outer-fan-side grounding device 40 includes a grounding brush 41, a brush holder 42, a support bracket 43, and a drive support portion 44.

The grounding brush 41 is stationary fixed by a support bracket 43. One surface of the grounding brush 41 is pressed against the surface of the rotating shaft 11 by a brush holder 42 fixedly supported by a support bracket 43. In the rotating state of the rotating shaft 11, the sliding state between the surface of the grounding brush 41 and the surface of the rotating shaft 11 is maintained.

The driving support portion 44 includes a movable support portion 45 and a driving portion 46, and the driving portion 46 drives and moves the support bracket 43 fixedly supported by the movable support portion 45. The movement support portion 45 extends radially outward from the vicinity of the surface of the rotating shaft 11 to the vicinity of the processing opening 37a of the outer fan cover 37 (fig. 1). The movement support portion 45 incorporates a rotation shaft 45a that rotates about an axis extending in the axial direction. The rotary shaft 45a is threaded and is rotationally driven by a driving unit 46.

Fig. 4 is a conceptual diagram for explaining the structure and operation of the driving support portion 44. The movement support portion 45 includes a rotating shaft 45a, a bearing 45b, a second gear 45c for speed reduction, and an axial movement transmission portion 45 d. The support bracket 43 holding the grounding brush 41 is moved radially outward to replace the grounding brush 41, and the moving direction is referred to as a brush moving direction.

The rotating shaft 45a extends in the brush moving direction, and both ends thereof are rotatably supported by bearings 45b such that the rotating shaft 45a does not move in the brush moving direction. The rotary shaft 45a is configured to be rotatable in both forward and reverse directions. A portion of the rotating shaft 45a sandwiched by the two bearings 45b is formed with a male screw. The second gear 45c for speed reduction is provided outside the bearing on the side of the rotating shaft 45 a.

The axial movement conduction portion 45d is formed with a through hole through which the rotation shaft 45a passes. A portion of the through hole facing the rotation shaft is formed with a female screw corresponding to the male screw formed on the rotation shaft 45 a. The axially moving conductive portion 45d is coupled to the support bracket 43. The support bracket 43 is configured to be movable only in the brush moving direction by a guide not shown. Therefore, the axial movement conduction portion 45d and the support bracket 43 coupled thereto move in the brush movement direction so as not to rotate in a plane perpendicular to the brush movement direction by the rotation of the rotating shaft 45 a.

The driving unit 46 includes a driving motor 46a and a first gear 46b for speed reduction. The drive motor 46a is rotatable in both forward and reverse directions, and rotates the first gear 46b for speed reduction. The first reduction gear 46b transmits the rotation to the second reduction gear 45c, and rotates the rotation shaft 45 a. Further, although the case where the drive motor 46a is reversed to reverse the rotation direction of the rotary shaft 45a is shown, the present invention is not limited to this. For example, when the rotation direction of the rotating shaft 45a is reversed, a system in which a gear not shown is interposed between the first gear 46b for reduction and the second gear 45c for reduction may be substituted.

In the present embodiment, a case has been described in which a rotating shaft or the like having a male screw formed therein is used to move the support bracket 43 holding the grounding brush 41 between the attachment position near the surface of the rotating shaft 11 and the vicinity of the inner surface of the outer fan cover 37, but the present invention is not limited to this. For example, the system may be a movable system including a system using a crawler belt.

The embodiments of the present invention have been described above, but the embodiments are presented as examples and are not intended to limit the scope of the present invention. The embodiments may be implemented in other various forms, and various omissions, substitutions, and changes may be made without departing from the spirit of the invention. The embodiments and modifications thereof are included in the scope and spirit of the present invention, and also included in the invention described in the claims of the present patent application and the equivalent scope thereof.

Description of the reference symbols

10 rotor

11 rotating shaft

11a coupling part

12 rotor core

13 rotor rod

14 short-circuit ring

15 inner fan

20 stator

21 stator core

22 stator coil

31 frame

32 outer fan side bearing

33 coupling side bearing

35 external fan

37 outer fan cover plate

37a treatment opening

37b suction inlet

38 coupling side earthing device

40 external fan side grounding device

41 ground brush

42 electric brush pressing piece

43 support bracket

44 drive support

45 moving support part

45a rotary shaft

45b bearing

45c second gear for speed reduction

45d axial movement conducting part

46 drive part

46a drive motor

46b first gear for speed reduction

100 rotating electric machine

Claims

1. A rotating electrical machine, characterized by comprising:

a rotor having a rotating shaft rotatably supported by a shaft, extending in an axial direction at a center of the rotating shaft, and a rotor core provided outside the rotating shaft;

a stator having a stator core disposed radially outward of the rotating shaft and a stator coil provided in a slot formed in the stator core; and

a grounding device for preventing static electricity from accumulating in the rotor,

the grounding device includes:

a grounding brush which is statically fixed to the rotating shaft in a pressure-welded state;

a support bracket that statically supports the grounding brush in a press-contact state with the rotating shaft;

a brush presser rotatably supported by the support bracket and pressing the grounding brush so that the grounding brush is pressed against the rotating shaft; and

a drive support portion formed so as to be movable between a mounting position and a position on the radially outer side where the brush replacement can be safely performed,

the drive support portion includes:

a movable support part which movably supports the support bracket through a rotating shaft having a male screw formed thereon and rotatably supported at both ends thereof, extends radially outward, and is fixed in position in a radial direction, the male screw being screwed with a female screw formed on the support bracket; and

and a driving unit that drives the rotation shaft to rotate and drives the support bracket to move along the movement support unit.

2. The rotating electric machine according to claim 1,

comprising:

a frame that houses the rotor core and the stator;

an outer fan side bearing and a coupling side bearing which rotatably support both sides of the rotating shaft in the main shaft direction; and

an outer fan mounted on an axially outer side of the outer fan-side bearing,

the portion of the rotating shaft to which the grounding brush is fixed in a pressed state is a portion sandwiched between the outer fan and the outer fan-side bearing.