CN112366896B

CN112366896B - Motor and electrical equipment

Info

Publication number: CN112366896B
Application number: CN201910683820.8A
Authority: CN
Inventors: 李国雄; 陈丹; 曾路强; 黄成栋; 吕玉婵; 李虎; 陈国勇
Original assignee: Guangdong Welling Motor Manufacturing Co Ltd
Current assignee: Guangdong Welling Motor Manufacturing Co Ltd
Priority date: 2019-07-26
Filing date: 2019-07-26
Publication date: 2021-11-30
Anticipated expiration: 2039-07-26
Also published as: CN112366896A; WO2021017190A1

Abstract

The invention belongs to the technical field of motors, and relates to a motor and electrical equipment with the motor. The motor is provided with a shaft sleeve structure, a rotor shaft is sleeved with a shaft sleeve part of the shaft sleeve structure, the shaft sleeve part is electrically connected with the bearing bracket, and the motor is equivalent to a regulating capacitor which is connected with the bearing capacitor in parallel and is additionally arranged on the outer ring and the inner ring of the bearing. On one hand, the adjustment capacitor increases the equivalent bearing capacitance between the bearing outer ring and the bearing inner ring, so that the shaft voltage between the bearing outer ring and the bearing inner ring is reduced; on the other hand, the shaft current can be shunted, so that the current between the bearing bracket and the rotor shaft is shunted from the branch of the adjusting capacitor, and the shaft current flowing through the bearing outer ring and the bearing inner ring is effectively reduced, therefore, the occurrence of the bearing electric corrosion damage is effectively inhibited. The motor has the characteristics of simple structure, convenience in assembly, high reliability and low cost.

Description

Motor and electrical equipment

Technical Field

The invention belongs to the technical field of motors, and particularly relates to a motor improved for preventing bearing electric corrosion and electrical equipment with the motor.

Background

In recent years, due to the trend of energy saving of electrical equipment, the adopted motor generally replaces an induction motor with a high-efficiency brushless direct current motor, such as an air conditioning unit, and the high-efficiency brushless direct current motor is adopted to drive a fan. These brushless dc motors are driven by inverters that use a pulse width modulation method (hereinafter, referred to as PWM) as a driving method. In the PWM driving method, the neutral point potential of the winding is not zero, so that a common-mode voltage is generated, a coupling capacitor is generated between motor structures under the condition of high frequency, the common-mode voltage forms a loop through the coupling capacitor among the stator, the rotor, the permanent magnet, the end cover and the like and a bearing capacitor, so that a voltage is generated on a bearing capacitor branch circuit, and the voltage generated between the inner ring and the outer ring of the bearing (the bearing capacitor branch circuit) by the common-mode voltage is called as a shaft voltage. The shaft voltage contains high-frequency components of semiconductor high-speed switching action in PWM driving, if the shaft voltage reaches the insulation breakdown voltage of a lubricating oil film in the bearing, the shaft voltage is discharged along with the insulation breakdown voltage to generate current, and then the inner surface of the bearing and the balls are subjected to local erosion, namely the bearing is subjected to electric corrosion. When the galvanic corrosion gradually progresses, a wave-shaped wear phenomenon occurs on the bearing, eventually causing abnormal noise and a reduction in the life of the bearing.

In order to prevent the electric corrosion of the bearing, many proposals are put forward in the industry, and the proposals can be summarized into the following 3 types in general: (1) the method comprises the following steps of (1) enabling the inner ring and the outer ring of the bearing to be in a conducting state, (2) enabling the inner ring and the outer ring of the bearing to be in a reliable insulating state, and (3) reducing the shaft voltage. The method (1) has been proposed to use a conductive bearing grease, but it is difficult to use the grease because the same life as a non-conductive grease cannot be achieved and the cost is high. In addition, there is a method of providing a conductive brush on a shaft, which has problems such as wear of the brush, a need for a space, a high cost of implementation, and a need for maintenance. For the method (2), the practical product application has the case of using the ceramic ball bearing, which has better effect, but the ceramic ball bearing is very expensive and is difficult to be applied on a large scale, especially in some application occasions with high requirements on cost. In the method (3), various invention technologies for reducing the shaft voltage are proposed, and in the invention patent CN101971460B, an insulating layer is provided between the inner side and the outer side of the motor rotor to increase the impedance of the rotor, so that the shaft voltage can be greatly reduced from several tens of volts to less than ten volts, and the shaft voltage gradually becomes smaller as the thickness of the insulating layer increases. However, the rotor of this type has a complicated structure, high implementation cost, low rotor strength, and poor reliability.

Disclosure of Invention

The embodiment of the invention aims to provide a motor to solve the technical problems that in the prior art, a scheme for preventing the motor bearing from being corroded electrically is high in cost, not easy to implement and low in reliability.

An embodiment of the present invention provides a motor, including:

a stator including a stator core having a winding;

a rotor rotatably mounted on the stator, the rotor including a rotor core and a rotor shaft located at a center of the rotor core and connected to the rotor core;

the bearing supports the rotor shaft and comprises a bearing inner ring and a bearing outer ring, and the bearing inner ring is connected with the rotor shaft;

a bearing bracket that fixes and conducts the bearing outer ring; and

the shaft sleeve structure is used for adjusting equivalent capacitance between the bearing inner ring and the bearing outer ring, and comprises a shaft sleeve part electrically connected with the bearing bracket, the shaft sleeve part is sleeved on the rotor shaft, and an adjusting capacitor is formed between the shaft sleeve part and the rotor shaft.

Optionally, the number of the bearings is two, two bearings are arranged on two sides of the rotor core at intervals along the axial direction of the rotor core, and each bearing is correspondingly connected with one bearing bracket; at least one of the bearing brackets is provided with the bushing structure.

Optionally, the motor further comprises a conducting member, and the two bearing brackets are electrically connected through the conducting member.

Optionally, the stator core outside is equipped with moulds the capsule, it is the bar to switch on the piece, it follows to switch on a part the axial setting of stator is in mould the outer peripheral face of capsule, another part that switches on the piece is followed the radial setting of stator is in one of them terminal surface of plastic envelope shell, the both ends one-to-one that switches on the piece is connected in two on the bearing bracket.

Optionally, the shaft sleeve structure further includes a connecting portion connected to the shaft sleeve portion, and the connecting portion is disposed on the bearing bracket and electrically connected to the bearing bracket.

Optionally, the connecting portion and the boss portion are integrally molded metal pieces.

Optionally, the bearing bracket has a bearing support portion, and the connecting portion is sleeved on an outer circumferential surface of the bearing support portion.

Alternatively, the connecting portion is press-fitted to an outer peripheral surface of the bearing support portion.

Optionally, the boss structure is integrally molded with the bearing bracket.

Optionally, an end cover is disposed at one axial end of the stator, the bearing bracket is disposed on the end cover, and the end cover includes a stator bracket located at an outer circumferential side of the stator and a support plate for connecting the bearing bracket and the stator bracket.

Optionally, the end cap is an integrally molded metal piece.

Optionally, the sleeve portion includes an outer sleeve close to the outer circumferential surface of the rotor shaft, and a first air gap is formed between the inner circumferential surface of the outer sleeve and the outer circumferential surface of the rotor shaft.

Optionally, the inner circumferential surface of the outer sleeve is a cylindrical surface, the outer circumferential surface of the portion of the rotor shaft penetrating into the outer sleeve is a cylindrical surface, and the outer sleeve and the rotor shaft are coaxially arranged.

Optionally, the distance of the first air gap is less than or equal to 0.3 mm.

Optionally, the one end of the axial direction of rotor shaft has the shaft hole that extends along the axial direction, axle sleeve portion still includes interior axle sleeve, interior axle sleeve is at least partly set up in the shaft hole, the outer peripheral face of interior axle sleeve with form the second air gap between the shaft hole inner wall of rotor shaft.

Optionally, the outer circumferential surface of the inner sleeve is a cylindrical surface, the circumferential surface of the shaft hole of the rotor shaft is a cylindrical surface, and the inner sleeve and the rotor shaft have the same axis.

Optionally, the distance of the second air gap is less than or equal to 0.3 mm.

Optionally, one end of the inner shaft sleeve, which extends into the shaft hole, is a closed end, and the same end surface of the outer shaft sleeve and the inner shaft sleeve is connected through an annular closing plate;

or the same end surfaces of the outer shaft sleeve and the inner shaft sleeve are connected through a whole sealing plate.

Optionally, a ratio of a facing area of the first air gap to a distance is greater than or equal to 3.4 m.

Optionally, the sum of the ratio of the facing area to the distance of the first air gap and the ratio of the facing area to the distance of the second air gap is greater than or equal to 3.4 m.

Optionally, the shaft sleeve portion is disposed on a side of the bearing bracket opposite to the stator core, and is sleeved on at least a portion of the rotor shaft exposed out of the bearing bracket;

or the shaft sleeve part is arranged on one side of the bearing bracket, which faces the stator core, and is sleeved on at least one part of the rotor shaft, which is hidden inside the bearing bracket.

The embodiment of the invention provides electrical equipment which comprises the motor.

One or more technical schemes in the motor and the electrical equipment provided by the embodiment of the invention at least have one of the following technical effects: the motor is provided with a shaft sleeve structure, a rotor shaft is sleeved with a shaft sleeve part of the shaft sleeve structure, the shaft sleeve part is electrically connected with the bearing bracket, and the motor is equivalent to a regulating capacitor which is connected with the bearing capacitor in parallel and is additionally arranged on the outer ring and the inner ring of the bearing. On one hand, the adjustment capacitor can increase the equivalent bearing capacitance between the bearing outer ring and the bearing inner ring, and can reduce the shaft voltage between the bearing outer ring and the bearing inner ring; on the other hand, the shaft current can be shunted, so that the current between the bearing bracket and the rotor shaft is shunted from the branch of the adjusting capacitor, and the shaft current flowing through the bearing outer ring and the bearing inner ring is effectively reduced, therefore, the occurrence of the bearing electric corrosion damage is effectively inhibited. The motor and the electrical equipment with the motor have the characteristics of simple structure, convenience in assembly, high reliability and low cost. Need not to set up the insulating layer in the rotor core of this motor, ensure rotor bonding strength, avoid current rotor core insulating layer to take place ageing along with the rise of temperature and the increase of live time, and then ensure the reliability of motor.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.

Fig. 1 is a partial cross-sectional view of a motor provided in accordance with an embodiment of the present invention;

fig. 2 is an exploded perspective view of a motor according to an embodiment of the present invention;

fig. 3 is a partial cross-sectional view of a motor provided in accordance with another embodiment of the present invention;

FIG. 4 is a cross-sectional view of the motor of FIG. 3 taken along line A-A;

fig. 5 is a sectional view of a rotor applied in the motor of fig. 3;

fig. 6 is a perspective view illustrating a bushing structure applied to the motor of fig. 3;

FIG. 7 is a cross-sectional view of the bushing structure of FIG. 6;

fig. 8 is a partial cross-sectional view of a motor provided in accordance with another embodiment of the present invention;

fig. 9 is a partial cross-sectional view of an end cap for use in the motor of fig. 8;

fig. 10 is a partial cross-sectional view of a motor provided in accordance with another embodiment of the present invention;

FIG. 11 is a cross-sectional view of the motor of FIG. 10 taken along line B-B;

fig. 12 is a partial cross-sectional view of a rotor employed in the motor of fig. 10;

fig. 13 is a perspective assembly view of a rotor employed in the motor of fig. 10;

fig. 14 is a partial cross-sectional view of an end cap for use in the motor of fig. 10.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

In the description of the embodiments of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the embodiments of the present invention and simplifying the description, but do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the embodiments of the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the embodiments of the present invention, unless otherwise explicitly specified or limited, the terms "mounted," "connected," "fixed," and the like are to be construed broadly, e.g., as being fixedly connected, detachably connected, or integrated; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. Specific meanings of the above terms in the embodiments of the present invention can be understood by those of ordinary skill in the art according to specific situations.

Referring to fig. 1, 3, 8 and 10, an embodiment of the invention provides a motor including a stator 10, a rotor 20, a bearing 30, a bearing bracket 40 and a shaft sleeve structure 50. The stator 10 includes a stator core 11 having a winding 111. The stator core 11 may be molded with a resin material, and the molded case 12 may be molded outside the stator core 11. The rotor 20 is rotatably mounted on the stator 10, and referring to fig. 5 and 13, the rotor 20 includes a rotor core 21 and a rotor shaft 22 located at the center of the rotor core 21 and connected to the rotor core 21, the rotor core 21 may include a permanent magnet 211, and the rotor core 21 and the rotor shaft 22 rotate synchronously.

The bearing 30 supports the rotor shaft 22 such that the rotor shaft 22 can rotate freely. The bearing 30 includes a bearing inner ring 31 and a bearing outer ring 32, the bearing inner ring 31 is sleeved on the outer circumferential surface of the rotor shaft 22 and is limited on the rotor shaft 22 along the axial direction of the rotor shaft 22, and the bearing inner ring 31 is communicated with the rotor shaft 22. The bearing outer ring 32 is mounted on the bearing bracket 40, and is limited on the bearing bracket 40 along the radial direction and the axial direction, and the bearing outer ring 32 is communicated with the bearing bracket 40. Rolling elements 33 are provided between the bearing outer ring 32 and the bearing inner ring 31 so that the bearing outer ring 32 and the bearing inner ring 31 can rotate freely. At least a portion of the bearing bracket 40 connected to the bearing outer race 32 is made of a conductive material, and is used for fixing and conducting the bearing outer race 32.

The sleeve structure 50 is used to adjust the equivalent capacitance between the bearing inner race 31 and the bearing outer race 32. The shaft sleeve structure 50 includes a shaft sleeve portion 51, the shaft sleeve portion 51 is made of a conductive material, and the shaft sleeve portion 51 is electrically connected to the bearing bracket 40. Here, the electrical connection includes direct and indirect conductive connection, as well as connection via a large capacitance. Through the connection of a large capacitor, for example, a very thin insulating layer is arranged between two metal parts, and as long as the two metal parts are close enough and the facing area is large enough, the capacitance value between the two metal parts is large enough. The sleeve portion 51 is fitted over the rotor shaft 22, and the sleeve portion 51 is insulated from the rotor shaft 22. A tuning capacitance C1 is formed between the boss portion 51 and the rotor shaft 22.

A shaft sleeve structure 50 is arranged on a motor, a shaft sleeve part 51 of the shaft sleeve structure 50 is sleeved on at least one part of a rotor shaft 22, which is equivalent to adding a conductive polar plate on the circumferential side of the rotor shaft 22, a regulating capacitor C1 is formed between the polar plate and the rotor shaft 22, the shaft sleeve part 51 (namely, the polar plate) is electrically connected with a bearing bracket 40, a bearing inner ring 31 is considered to extend partially by the rotor shaft 22, a bearing outer ring 32 is considered to extend partially by the shaft sleeve structure 50, the two extending parts have opposite areas and are not communicated, so that a regulating capacitor C1 is formed, and the regulating capacitor C1 is equivalent to be connected between the bearing outer ring 32 and the bearing inner ring 31 in parallel. If one bearing 30 is respectively disposed at two ends of the rotor core 21, that is, two bearings 30 are disposed on the rotor core 21, a high-frequency equivalent circuit between the bearing outer ring 32 and the bearing inner ring 31 of one bearing 30 may be equivalent to a coupling capacitor Cb1, and a high-frequency equivalent circuit between the bearing outer ring 32 and the bearing inner ring 31 of the other bearing 30 may be equivalent to a coupling capacitor Cb2, where the shaft voltage is a voltage division voltage on Cb1 and Cb 2.

Each bearing 30 is mounted on a respective bearing bracket 40, and the inner bearing rings 31 of both bearings are electrically conductively connected to the rotor shaft. For the sake of simplicity of analysis, the description is made in the case where the two bearing brackets 40 are electrically connected, and the capacitances Cb1 and Cb2 are equivalent to parallel connection. The above-mentioned shaft sleeve part 51 is arranged to be equivalent to that the adjusting capacitor C1 is connected in parallel to the bearing capacitors Cb1 and Cb2, and the total capacitance of the parallel connection of Cb1, Cb2 and C1 is the above-mentioned "equivalent capacitance", and it can be understood that, when the two bearing brackets 40 (or the bearing outer race 32) are not electrically connected, Cb1 or Cb2 is connected in parallel to C1, and the total capacitance of the parallel connection of the two is the above-mentioned "equivalent capacitance". Each of Cb1 and Cb2 is a bearing capacitance corresponding to the bearing itself, and is related to a facing area between a bearing inner ring and a bearing outer ring of the bearing itself, and the bearing capacitance is also determined for a predetermined bearing. The equivalent capacitance is denoted as Cb, and the size of the adjusting capacitance C1 and the size of the equivalent capacitance Cb can be effectively changed by adjusting the facing area of the sleeve portion 51 and the rotor shaft 22 and the size of the air gap therebetween. For convenience of description, a capacitance formed by the bearing outer ring 32 and the stator core 11 through the bearing bracket 40 is Cd, and an equivalent capacitance formed by the bearing inner ring 31 and the stator core 11 through the rotor shaft 22, the permanent magnet 211, and an air gap between the stator 10 and the rotor 20 is Cz. The coupling capacitance loop formed by the whole motor comprises the equivalent capacitances Cb, Cd and Cz.

The motor that this embodiment provided has following technological effect: the capacitor C1 is adjusted in parallel to the bearing capacitors Cb1 and Cb2 to increase the equivalent capacitor Cb, so that the voltage difference across the equivalent capacitor Cb is reduced. On one hand, the parallel connection of the capacitor C1 is adjusted, so that the equivalent capacitor Cb is increased, and the equivalent capacitor Cb obtains smaller partial voltage, that is, the voltage difference between the bearing inner ring 31 and the bearing outer ring 32 is reduced, thereby realizing the reduction of the shaft voltage; on the other hand, when the adjusting capacitor C1 is relatively large with respect to both the bearing capacitors Cb1 and Cb2, the current between the bearing bracket 40 and the rotor shaft 22 will pass through the branch of the adjusting capacitor C1, and the shaft current will be shunted, so that the current passing through the bearing outer ring 32 and the bearing inner ring 31, i.e. the shaft current, is reduced, and therefore, the risk of electrical corrosion damage to the bearing 30 can be greatly reduced.

The motor is only provided with the shaft sleeve structure 40 on the bearing bracket, and the adjusting capacitor C1 is formed between the motor and the rotor shaft 22, the internal structure of the rotor or the stator does not need to be adjusted, and the motor has the characteristics of simple structure, convenience in assembly, high reliability and low cost.

Further, conventional machines employing insulated rotors are considered in the industry as being more effective methods of reducing shaft voltage. According to the simulation verification of the circuit model of the invention patent (with the publication number of CN101971460B) in the plastic package motor for the air conditioner, the method can be obtained on the DC brushless motor with the outer diameter of 92mm used in the small air conditioner, and the same conclusion can be obtained, namely compared with the motor without a rotor insulating layer, the shaft voltage of the motor with the insulating layer increased by the rotor can be reduced, and the shaft voltage is gradually reduced along with the increase of the insulating layer. However, on motors having an outer diameter of 92mm or more used in some larger air conditioners, the opposite conclusion is reached that the rotor adds an insulating layer, the motor shaft voltage conversely rises, and the shaft voltage gradually increases as the thickness of the insulating layer increases. Therefore, the application of the inventive technique has certain limitations. In addition, the technology of the invention needs to carry out great improvement on the rotor structure, needs to add a rotor outer iron core high-punching die, a rotor inner iron core high-punching die and a rotor insulating layer injection die, needs to add the dies corresponding to each motor with different sizes, and has high implementation cost and complex manufacturing process. In summary, such rotors with an insulating layer have a number of disadvantages, including limitations in use, over conventional rotors without an insulating layer; the material cost and the manufacturing cost are greatly increased; the rotor bonding strength is reduced due to the addition of the insulating layer in the rotor core; the insulating layer in the rotor is deteriorated with an increase in temperature and an increase in service time, resulting in a decrease in product reliability, etc.

In the present embodiment, the above-mentioned problem can be avoided by using the above-mentioned sleeve structure 40, and the electric corrosion of the bearing 30 can be effectively prevented for all dc motors, and the electric corrosion of the bearing 30 can be prevented even for motors having an outer diameter of 92mm or more. An insulating layer is not required to be arranged in the rotor core 21 of the motor, the bonding strength of the rotor 20 is ensured, the phenomenon that the insulating layer of the existing rotor core is aged along with the rise of temperature and the increase of service time is avoided, and the reliability of the motor is further ensured.

Referring to fig. 1, in another embodiment of the present invention, the number of the bearings 30 is two, two bearings 30 are disposed at intervals along the axial direction of the rotor core 21 on both sides of the rotor core 21, and each bearing 30 is connected to a bearing bracket 40. The two sets of bearings 30 are provided at intervals, are positioned so as to sandwich the rotor core 21 in the axial direction, and rotatably support the rotor shaft 22. Two sets of bearings 30 are mounted on two bearing brackets 40, respectively. The bearing bracket 40 on the shaft extension side X and the outer part of the stator core 11 are subjected to plastic molding to form the plastic package 12, and the bearing bracket 40 on the non-shaft extension side X' is arranged on the plastic package 12. At least one bearing bracket 40 is provided with a bushing structure 50, and a regulating capacitance C1 is formed by the bushing structure 50, so as to reduce the shaft voltage and the shaft current flowing through the bearing outer ring 32 and the bearing inner ring 31. The shaft sleeve structure 50 may be disposed on at least one of the shaft extension side X and the non-shaft extension side X' of the rotor shaft 22, and is disposed as required.

Referring to fig. 1 and 2, in another embodiment of the present invention, the shaft sleeve structure 50 further includes a connecting portion 52 connected to the shaft sleeve portion 51, and the connecting portion 52 is disposed on the bearing bracket 40 and electrically connected to the bearing bracket 40. The structure is easy to form and assemble. Specifically, the bushing structure 50 may be assembled on the bearing bracket 40 (shown in fig. 1 and 3), and the bushing structure 50 may be integrally formed on the bearing bracket 40 (shown in fig. 8 and 10). In both schemes, the connection portion 52 may be electrically connected to the bearing bracket 40, and the connection portion 52 may be connected to the sleeve portion 51, so that the sleeve portion 51 is electrically connected to the bearing bracket 40, and the adjustment capacitor C1 is formed between the sleeve portion 51 and the rotor shaft 22, and the adjustment capacitor C1 is connected in parallel to the bearing capacitors Cb1 and Cb 2.

Referring to fig. 1 and 2, in another embodiment of the present invention, the connecting portion 52 and the shaft sleeve portion 51 are integrally molded metal pieces, and are easily processed by an integrally molding process. Specifically, the sleeve structure 50 may be made of aluminum or other metal, and is electrically conductive and easy to press-mold.

In another embodiment of the present invention, the bushing structure 50 is assembled on the bearing bracket 40 when the bearing bracket 40 is manufactured by stamping and drawing. The bearing bracket 40 has a bearing support portion 41 for mounting the bearing 30, the connecting portion 52 is substantially cylindrical, and the shaft sleeve structure 50 and the bearing bracket 40 can be assembled and electrically connected by fitting the connecting portion 52 on the outer peripheral surface of the bearing support portion 41. Preferably, the outer diameter of the connecting portion 52 is larger than the outer diameter of the boss portion 51, so that the thickness of the first air gap 53 between the boss portion 51 and the rotor shaft 22 is relatively suitable, forming a predetermined adjustment capacitance C1.

Further, the connecting portion 52 is connected to the outer peripheral surface of the bearing support portion 41 by pressure welding. The connection portion 52 is fixed outside the bearing support portion 41 by a crimping process, so that the assembly is easy, and the connection between the connection portion and the bearing support portion is reliable and conductive.

Further, in the mode of assembling the sleeve structure 50 to the bearing bracket 40, the two bearing brackets 40 are electrically connected by the conductive member 60, which is equivalent to electrically connecting the two bearing outer rings 32, and the bearing inner rings 31 of the two bearings 30 are electrically connected by the rotor shaft 22, so that the effect of providing the adjusting capacitor C1 affects the shaft voltages of the two bearings 30 at the same time, and the effect of reducing the risk of the occurrence of the electrical corrosion of the two bearings 30 at the same time is achieved.

Specifically, referring to fig. 1, the lead-through 60 may be disposed outside the stator 10. The two bearing brackets 40 are respectively located on the axial extending side X and the non-axial extending side X'. The conducting piece 60 is in a strip shape, one part of the conducting piece 60 is arranged on the outer circumferential surface of the plastic package casing 12 along the axial direction of the stator 10, and the other part of the conducting piece 60 is arranged on one end surface of the plastic package casing 12 along the radial direction of the stator 10. The bearing bracket 40 located on the shaft extension side X covers the other end face of the stator core 11. The bearing bracket 40 has a slot 42, and one end 60a of the conducting member 60 is bent at the edge of the plastic package case 12 and inserted into the slot 42 to connect the one end 60a of the conducting member 60 with one bearing bracket 40. The bearing bracket 40 on the non-axial side X' abuts against the other end 60b of the conducting member 60 and may be connected by a fastening member 61. This solution is easy to assemble, compact and allows the conduction of the two bearing brackets 40. With further reference to fig. 2, the outer surface of the stator plastic capsule 12 is provided with a mounting groove 121 for mounting the lead-through 60. During assembly, the conducting member 60 is mounted in the mounting groove 121, so that the conducting member 60 is conveniently assembled. It is understood that the conducting member 60 may be disposed inside the stator 10 to conduct the two bearing brackets 40.

Referring to fig. 8 to 10, in another embodiment of the present invention, when the shaft sleeve structure 50 and the bearing bracket 40 are integrally molded, the shaft sleeve structure 50 and the bearing bracket 40 are made of conductive materials, and the structure is easy to mold and does not need to be assembled. Specifically, the sleeve structure 50 and the bearing bracket 40 may be made of aluminum or other metal, and are electrically conductive and easy to press-mold.

Further, referring to fig. 8, an end cover 70 is provided at one axial end of the stator 10, the bearing bracket 40 is provided on the end cover 70, and the end cover 70 includes a stator bracket 71 located at an outer circumferential side of the bearing bracket 40 and a support plate 72 for connecting the bearing bracket 40 and the stator bracket 71. The stator bracket 71 is disposed on the same side of the support plate 72 as the bearing bracket 40, and the bushing structure 50 is disposed on the other side of the support plate 72. In assembly, the end cap 70 covers an end face of the stator core 11, the stator bracket 71 is used for mounting the stator 10, the bearing bracket 40 is used for mounting one of the bearings 30, and the bushing structure 50 cooperates with the rotor shaft 22 to form the regulating capacitor C1.

Further, the end cap 70 is a unitary molded metal piece. That is, the bearing bracket 40, the end cap 70 and the boss structure 50 are integrally formed, which simplifies assembly.

Further, referring to fig. 8 and 10, when the shaft sleeve structure 50 and the bearing bracket 40 are integrally molded, the two bearing brackets 40 are electrically connected through the conducting member 60 disposed at the outer side of the stator 10, which is equivalent to electrically connecting the two bearing outer rings 32, and the bearing inner rings 31 of the two bearings 30 are electrically connected through the rotor shaft 22, so that the effect of disposing the adjusting capacitor C1 affects the shaft voltages of the two bearings 30 at the same time, and the effect of reducing the risk of the occurrence of the electrical corrosion of the two bearings 30 at the same time is achieved.

Specifically, the two bearing brackets 40 are respectively located on the axial extending side X and the non-axial extending side X'. The conducting piece 60 is in a strip shape, one part of the conducting piece 60 is arranged on the outer circumferential surface of the plastic package casing 12 along the axial direction of the stator 10, and the other part of the conducting piece 60 is arranged on one end surface of the plastic package casing 12 along the radial direction of the stator 10. The non-axial-extending side X' of the stator core 11 is covered with an end cover 70. One end 60a of the conducting piece 60 is abutted with the bearing bracket 40 positioned on the shaft extension side X and can be connected with the stator bracket 71 through a fastening piece 61, the other end 60b of the conducting piece 60 is abutted with the stator bracket 71, and the stator bracket 71 is electrically connected with the bearing bracket 40 positioned on the non-shaft extension side X' through a supporting disc 72, so that the two bearing brackets 40 are electrically connected. Further, the outer surface of the stator plastic capsule 12 is provided with a mounting groove for mounting the lead-through 60. When assembling, the conducting piece 60 is directly installed in the installation groove, and the assembly is easy.

Referring to fig. 1, 3, 4 and 6, in another embodiment of the present invention, the sleeve portion 51 includes an outer sleeve 511 close to the outer peripheral surface 22a of the rotor shaft 22, and a first air gap 53 is formed between the inner peripheral surface of the outer sleeve 511 and the outer peripheral surface 22a of the rotor shaft 22. When the boss portion 51 of the boss structure 50 is electrically connected to the bearing bracket 40, an adjustment capacitance C1 is formed between the boss portion 51 and the rotor shaft 22, and the adjustment capacitance C1 is connected in parallel to the bearing capacitances Cb1 and Cb 2. On one hand, the shaft voltage between the bearing outer ring 32 and the bearing inner ring 31 can be reduced; on the other hand, the shaft current can be branched, so that the current between the bearing bracket 40 and the rotor shaft 22 is branched from the branch of the adjusting capacitor C1, and the shaft current flowing through the bearing outer ring 32 and the bearing inner ring 31 can be effectively reduced. The motors shown in fig. 8 and 11 are two other embodiments of the outer bushing 511.

Further, the inner peripheral surface of the outer sleeve 511 is a cylindrical surface, the outer peripheral surface 22a of the portion of the rotor shaft 22 inserted into the outer sleeve 511 is a cylindrical surface, and the outer sleeve 511 and the rotor shaft 22 are coaxially provided. This structure enables the thickness of the first air gap 53 between the outer hub 511 and the rotor shaft 22 to be relatively suitable, forming a predetermined adjustment capacitance C1. In addition, the outer sleeve 511 and the rotor shaft 22 are coaxially arranged, so that the assembly is easy and the structure is compact.

Further, the distance of the first air gap 53 is less than or equal to 0.3mm, so that the value of the adjusting capacitor C1 is relatively large, the equivalent capacitor Cb is increased, a smaller partial voltage is obtained at two ends of the equivalent capacitor Cb, that is, the voltage difference between the bearing inner ring 31 and the bearing outer ring 32 is reduced, and the reduction of the shaft voltage is realized. Meanwhile, by making the adjusting capacitor C1 larger than the bearing capacitors Cb1 and Cb2, the electric quantity at the two ends of the equivalent capacitor Cb can be more concentrated at the two ends of the adjusting capacitor C1, i.e., at the sleeve portion 51 and the rotor shaft 22 close to the sleeve portion 51, so as to reduce the shaft current.

Further, referring to fig. 3, 5 and 7, one end of the rotor shaft 22 in the axial direction has a shaft hole 221 extending along the axial direction, the shaft sleeve portion 51 includes an inner shaft sleeve 512, the inner shaft sleeve 512 is at least partially embedded in the shaft hole 221, and a second air gap 54 is formed between the outer peripheral surface of the inner shaft sleeve 512 and the inner wall 22b of the shaft hole 221 of the rotor shaft 22. By providing the inner sleeve 512 extending into the rotor shaft 22, the facing area of the sleeve portion 51 to the rotor shaft 22 is increased, and the adjustment capacitance C1 is increased. Further, the adjustment capacitor C1 is made larger than the bearing capacitors Cb1 and Cb2, so that the electric quantity at the two ends of the equivalent capacitor Cb is more concentrated at the two ends of the adjustment capacitor C1 to reduce the shaft current. The motor shown in fig. 10, 12 and 14 is another embodiment in which the shaft hole 221 and the inner sleeve 512 are provided.

Specifically, referring to fig. 3 and 7, one end of the inner sleeve 512 extending into the shaft hole 221 is a closed end. The same end faces of the outer hub 511 and the inner hub 512 are connected by an annular closing plate 513. Referring to fig. 10 and 14, the same end surfaces of the outer hub 511 and the inner hub 512 are connected by a full surface closing plate 513. When the shaft sleeve structure 50 is assembled to the motor, the closed end of the inner shaft sleeve 512 and the closing plate 513 can prevent foreign matters from entering the shaft hole 221, so as to ensure reliable operation of the shaft sleeve structure 50.

Further, the outer peripheral surface of the inner sleeve 512 is a cylindrical surface, the outer peripheral surface 22a of the shaft hole 221 of the rotor shaft 22 is a cylindrical surface, and the inner sleeve 512 and the rotor shaft 22 have the same axis. This configuration enables the second air gap 54 thickness between the inner hub 512 and the rotor shaft 22 to be relatively tailored to form a predetermined tuning capacitance C1. In addition, the inner sleeve 512 is coaxially disposed with the rotor shaft 22, so that the assembly is easy and the structure is compact.

Further, the distance of the second air gap 54 is smaller than or equal to 0.3mm, so that the value of the adjusting capacitor C1 is larger, the equivalent capacitor Cb is increased, a smaller partial voltage is obtained at two ends of the equivalent capacitor Cb, that is, the voltage difference between the bearing inner ring 31 and the bearing outer ring 32 is reduced, and the reduction of the shaft voltage is realized. Meanwhile, by making the adjusting capacitor C1 larger than the bearing capacitors Cb1 and Cb2, the electric quantity at the two ends of the equivalent capacitor Cb can be more concentrated at the two ends of the adjusting capacitor C1, i.e., at the sleeve portion 51 and the rotor shaft 22 close to the sleeve portion 51, so as to reduce the shaft current.

Referring to fig. 1, 3, 8, and 10, in another embodiment of the present invention, a rolling element 33 and grease are further disposed between the bearing outer ring 32 and the bearing inner ring 31, a formed capacitance mainly depends on an oil film, and in a state that the bearing 30 is stationary, the bearing capacitance is larger, and after the bearing rotates, the higher the rotation speed is, the more uniform the formed bearing oil film is, and the smaller the corresponding bearing capacitance is, and generally, after the rotation speed exceeds 1500r/min, the bearing capacitance value is substantially stable. The measured capacitance of the common 608-type bearing is 55PF, 33PF and 32PF respectively corresponding to 1000r/min, 1500r/min and 2000 r/min. Namely, the basic value of the bearing capacitance is more than 30 PF. The bushing structure 50 is provided, and a regulating capacitor C1 is formed between the bushing structure 50 and the rotor shaft 22, the regulating capacitor C1 is an air capacitor, and the relative dielectric constant and the absolute dielectric constant of air are fixed. It is the facing area and air gap distance that determines the tuning capacitance C1. If the ratio of the facing area of the two sides of the air gap to the air gap distance is greater than or equal to 3.4m, a tuning capacitance C1 greater than 30PF can be formed. The adjustment capacitance C1 between the bushing arrangement 50 and the rotor shaft 22 is then made larger than the bearing capacitances Cb1 and Cb2 between the outer bearing ring 32 and the inner bearing ring 31 of the corresponding bushing arrangement 50. Even if the adjusting capacitor C1 is greater than or much greater than the bearing capacitors Cb1 and Cb2, the electric quantity at the two ends of the equivalent capacitor Cb can be concentrated more at the two ends of the adjusting capacitor C1, i.e. at the sleeve portion 51 and the rotor shaft 22 close to the sleeve portion 51, so that most of the current between the bearing bracket 40 and the rotor shaft 22 passes through the branch of the adjusting capacitor C1, and the shaft current is shunted, thereby greatly reducing the current passing through the bearing outer ring 32 and the bearing inner ring 31, i.e. the shaft current, and therefore, the risk of electrical corrosion damage to the bearing 30 can be greatly reduced.

Specifically, referring to fig. 1 and 8, when the first air gap 53 is formed between the inner circumferential surface of the outer sleeve 511 and the outer circumferential surface 22a of the rotor shaft 22, the ratio of the facing area of the first air gap 53 to the distance is set to be greater than or equal to 3.4 m. Therefore, the adjusting capacitor C1 is larger or much larger than the bearing capacitors Cb1 and Cb2, and the effect of reducing the shaft current to reduce the electric corrosion of the bearing 30 is achieved.

Referring to fig. 3 and 10, when a first air gap 53 is formed between the inner circumferential surface of the outer sleeve 511 and the outer circumferential surface 22a of the rotor shaft 22 and a second air gap 54 is formed between the outer circumferential surface of the inner sleeve 512 and the inner wall 22b of the shaft hole 221 of the rotor shaft 22, the adjusting capacitance between the outer sleeve 511 and the outer circumferential surface 22a of the rotor shaft 22 and the adjusting capacitance between the inner sleeve 512 and the inner wall 22b of the shaft hole 221 of the rotor shaft 22 are connected in parallel, and the sum of the ratio of the facing area of the first air gap 53 to the distance and the ratio of the facing area of the second air gap 54 to the distance is greater than or equal to 3.4 m. Therefore, the adjusting capacitor C1 is larger or much larger than the bearing capacitors Cb1 and Cb2, and the effect of reducing the shaft current to reduce the electric corrosion of the bearing 30 is achieved.

In the above embodiments, the shaft sleeve portion 51 is disposed on a side of the bearing bracket 51 opposite to the stator core 11, and is sleeved on at least a portion of the rotor shaft 22 exposed from the bearing bracket 40. In other embodiments, when the non-shaft-extending side of the rotor shaft does not extend out of the bearing bracket, the sleeve portion may also be disposed on a side of the bearing bracket facing the stator core, and the sleeve portion is disposed on at least a portion of the rotor shaft hidden inside the bearing bracket.

In another embodiment of the present invention, an electrical apparatus is provided, which includes the above-mentioned motor.

The motor is provided with a shaft sleeve structure 50, a shaft sleeve part 51 of the shaft sleeve structure 50 is sleeved on the rotor shaft 22, and the shaft sleeve part 51 is electrically connected with the bearing bracket 40, which is equivalent to adding an adjusting capacitor C1 connected with the bearing capacitors Cb1 and Cb2 in parallel between the bearing outer ring 32 and the bearing inner ring 31. On one hand, the adjustment capacitor increases the equivalent bearing capacitance between the bearing outer ring 32 and the bearing inner ring 31, and can reduce the shaft voltage between the bearing outer ring 32 and the bearing inner ring 31; on the other hand, the shaft current can be branched to branch the current between bearing bracket 40 and rotor shaft 22 from adjusting capacitor C1, and the shaft current flowing through bearing outer ring 32 and bearing inner ring 31 can be effectively reduced, so that the occurrence of electric corrosion damage to bearing 30 can be effectively suppressed. The motor and the electrical equipment with the motor have the characteristics of simple structure, convenience in assembly, high reliability and low cost. An insulating layer is not required to be arranged in the rotor core 21 of the motor, the bonding strength of the rotor 20 is ensured, the phenomenon that the insulating layer of the existing rotor core is aged along with the rise of temperature and the increase of service time is avoided, and the reliability of the motor is further ensured.

The present invention is not limited to the above preferred embodiments, and any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An electric machine, comprising:

a stator including a stator core having a winding;

a bearing bracket that fixes and conducts the bearing outer ring; and

the shaft sleeve structure is used for adjusting equivalent capacitance between the bearing inner ring and the bearing outer ring, the shaft sleeve structure comprises a shaft sleeve part electrically connected with the bearing bracket, the shaft sleeve part is sleeved on the rotor shaft, an adjusting capacitance is formed between the shaft sleeve part and the rotor shaft, the shaft sleeve part comprises an outer shaft sleeve close to the outer peripheral surface of the rotor shaft, and a first air gap is formed between the inner peripheral surface of the outer shaft sleeve and the outer peripheral surface of the rotor shaft; the rotor comprises a rotor shaft, a shaft sleeve part and a rotor core, wherein one end of the rotor shaft in the axial direction is provided with a shaft hole extending along the axial direction, the shaft sleeve part further comprises an inner shaft sleeve, at least part of the inner shaft sleeve is embedded in the shaft hole, and a second air gap is formed between the outer peripheral surface of the inner shaft sleeve and the inner wall of the shaft hole of the rotor shaft; the tuning capacitance is greater than the bearing capacitance.

2. The motor of claim 1, wherein the number of the bearings is two, two bearings are arranged on two sides of the rotor core at intervals along the axial direction of the rotor core, and each bearing is correspondingly connected with one bearing bracket; at least one of the bearing brackets is provided with the bushing structure.

3. The motor of claim 2, further comprising a conducting member through which the two bearing brackets are electrically connected.

4. The motor according to claim 3, wherein a plastic package is disposed outside the stator core, the conducting member is in a bar shape, a part of the conducting member is disposed on an outer circumferential surface of the plastic package along an axial direction of the stator, another part of the conducting member is disposed on one end surface of the plastic package along a radial direction of the stator, and two ends of the conducting member are connected to the two bearing brackets in a one-to-one correspondence manner.

5. The motor of claim 1, wherein said bushing structure further comprises a connecting portion connected to said bushing portion, said connecting portion being disposed on and electrically connected to said bearing bracket.

6. The electric machine of claim 5 wherein said connecting portion and said sleeve portion are an integrally molded metal piece.

7. The motor according to claim 5, wherein the bearing bracket has a bearing support portion, and the connection portion is fitted over an outer circumferential surface of the bearing support portion.

8. The motor according to claim 7, wherein the connecting portion is press-fitted to an outer peripheral surface of the bearing support portion.

9. The motor of claim 1 wherein said bushing structure is integrally molded with said bearing bracket.

10. The motor according to claim 9, wherein an end cover is provided at one axial end of the stator, the bearing bracket is provided on the end cover, and the end cover includes a stator bracket located at an outer circumferential side of the stator and a support plate for connecting the bearing bracket and the stator bracket.

11. The electric machine of claim 10 wherein the end cap is an integrally molded metal piece.

12. The electric machine according to any one of claims 1 to 11, wherein an inner peripheral surface of the outer sleeve is a cylindrical surface, an outer peripheral surface of a portion of the rotor shaft inserted into the outer sleeve is a cylindrical surface, and the outer sleeve is disposed coaxially with the rotor shaft.

13. The electric machine of claim 12 wherein the distance of the first air gap is less than or equal to 0.3 mm.

14. The electric machine according to any one of claims 1 to 11, wherein the outer peripheral surface of the inner sleeve is a cylindrical surface, the peripheral surface of the shaft hole of the rotor shaft is a cylindrical surface, and the inner sleeve is coaxial with the rotor shaft.

15. The electric machine of claim 14, wherein the distance of the second air gap is less than or equal to 0.3 mm.

16. The electric machine according to any of claims 1 to 11, wherein the end of the inner sleeve extending into the shaft hole is closed, and the same end surface of the outer sleeve and the inner sleeve is connected by an annular closing plate;

17. An electrical machine according to any of claims 1 to 11, wherein the ratio of the facing area of the first air gap to the distance is greater than or equal to 3.4 m.

18. The electric machine of any of claims 1 to 11 wherein the sum of the ratio of the facing area to the distance of the first air gap and the ratio of the facing area to the distance of the second air gap is greater than or equal to 3.4 m.

19. The motor according to any one of claims 1 to 11, wherein the shaft sleeve portion is disposed on a side of the bearing bracket facing away from the stator core and is sleeved on at least a portion of the rotor shaft exposed from the bearing bracket;

20. Electrical apparatus, characterized in that it comprises an electrical machine according to any one of claims 1 to 19.