KR20230171787A - Anti erosion structure of motor - Google Patents

Abstract

The present invention is a motor electrostatic prevention structure in which a ground bearing is inserted into the hollow of the shaft, a conductor bar is installed on the rear cover, and the conductor bar contacts the bearing to ground the shaft, thereby preventing electrostatic phenomenon occurring on the fixed bearing side. It's about.

Description

Anti-corrosion structure of motor {ANTI EROSION STRUCTURE OF MOTOR}

The present invention relates to a structure to prevent electrical corrosion of a motor. More specifically, a ground bearing is inserted and installed into the hollow of the shaft, a conductor bar is installed on the rear cover, and the conductor bar contacts the bearing to ground the shaft to prevent damage occurring on the fixed bearing side. This relates to a motor electrostatic prevention structure that can prevent electrostatic phenomenon.

Recently, purely electric, eco-friendly vehicles such as electric vehicles or fuel cell vehicles have been attracting attention. These electric-powered eco-friendly vehicles are equipped with electric motors (hereinafter referred to as 'motor') as a driving source that obtains rotational power from electrical energy instead of internal combustion engines such as existing engines.

A motor used as a power source for an eco-friendly vehicle includes a housing, a stator fixedly installed inside the housing, and a rotor that is disposed with a certain gap from the stator and rotates around a shaft as a drive shaft. Motors used in eco-friendly vehicles receive three-phase AC power through an inverter. The inverter converts the battery's DC power into 3-phase AC through power module switching. At this time, the three-phase voltage is not in the form of a perfect sine wave, but is in the form of a square wave, so the total of the three-phase voltages is not 0. This is called common mode voltage. Due to the common-mode voltage applied to the coil of the motor, shaft voltage is generated on the shaft due to the parasitic capacitance inside the motor. Shaft voltage causes a potential difference between the inner and outer rings of the drive bearing that supports the shaft, and causes electrolysis of the drive bearing by the discharge mechanism inside the drive bearing. This electrolysis causes damage to the drive bearing, etc. It has a serious impact on the durability of

Figure 1 is a diagram showing the prior art. In the prior art, a ground ring (SGR, Shaft Ground Ring) that conducts electricity between the housing and the shaft is installed between the shaft and the housing to reduce the shaft voltage caused by the shaft of the motor. Simultaneously or separately, the drive bearing on the opposite side of the ground ring is made of an insulating ceramic ball bearing rather than a steel ball bearing. Since the ground ring must electrically ground the rotating shaft and the fixed housing, friction occurs between the ground ring and the shaft, and the durability of the ground ring inevitably deteriorates due to the friction generated. In addition, when the cooling oil inside the motor flows into the ground ring, the brush applied to the ground ring is coated with cooling oil, which increases the resistance on the ground ring side, and as a result, the brush applied to the ground ring is coated with cooling oil. There is a problem in that the amount of flowing current is reduced and the grounding performance of the ground ring is greatly reduced. Furthermore, ground rings and ceramic ball bearings have the disadvantage of being expensive.

Korean Patent Publication No. 10-1442414 (registered on September 12, 2014)

The present invention was made to solve the above problems, and its purpose is to provide a motor electrostatic prevention structure that can stably secure the grounding performance of the shaft, has a simple structure, is easy to manufacture, and is inexpensive to manufacture. Do it as

The electrostatic prevention structure of a motor according to an example of the present invention includes a housing that accommodates a stator, a rotor disposed inside the stator, and a shaft disposed inside the rotor; A rear cover coupled to the rear of the housing; and a grounding structure for grounding the shaft, wherein the grounding structure includes a ground bearing inserted into the hollow of the shaft and a conductor bar whose one side is fixed to the rear cover and the other side of which is in contact with the ground bearing. You can.

The ground bearing may be press-fitted into the hollow of the shaft so that the outer ring of the ground bearing is in close contact with the inner peripheral surface of the shaft, and the conductor bar may be in contact with the inner ring of the ground bearing.

The conductor bar includes a fixing part fixed to the rear cover and a protrusion extending from the fixing part and protruding toward the shaft, and at least a portion of the protrusion is inserted into the hollow of the ground bearing to form an inner ring of the ground bearing. It may be in contact with the outer circumferential surface of .

The protrusion of the conductor bar may be press-fitted into the hollow of the ground bearing to press the inner ring of the ground bearing radially outward.

The conductor bar is a rod member bent in a U-shape, and its central portion is formed in a ring shape to contact the inner ring of the ground bearing, and both ends may be respectively fixed to the rear cover.

Among the protrusions of the conductor bar, the part inserted into the hollow of the ground bearing is called the head, and the remaining part excluding the head is called the body. The head may be ring-shaped, and the body may be narrow.

The conductor bar may have a protruding spherical structure.

Among the protrusions of the conductor bar, the part inserted into the hollow of the ground bearing is called the head, and the remaining part excluding the head is called the body. The head may be spherical and the body may be narrow.

On the outer peripheral surface of the inner ring of the ground bearing, a guide groove may be formed with a predetermined indentation inward so that a portion of the protrusion of the conductor bar that is in contact with the inner ring of the ground bearing can be seated.

The conductor bar may be bolted to the rear cover.

The inside of the ground bearing may be filled with conductive grease.

The housing further accommodates a drive bearing installed on the shaft to support the shaft, and the bearing balls of the drive bearing may be made of steel balls.

According to the present invention, by preventing electrostatic corrosion in the driving bearing, it is possible to reduce the loss of the driving bearing due to electrostatic corrosion, reduce vibration and noise generated in the driving bearing due to the electrostatic phenomenon, and furthermore, it is possible to prevent conventional corrosion using ceramics to prevent electrostatic corrosion. The use of balls can be converted to steel balls, reducing the manufacturing cost of the motor.

1 is a diagram showing the prior art.
Figure 2 is an exploded perspective view of a motor according to an example of the present invention.
Figure 3 is a view viewed from the opposite direction of Figure 2.
Figure 4 is a cross-sectional perspective view before assembly of the housing and rear cover.
Figure 5 is a side view of Figure 4.
Figure 6 is a cross-sectional perspective view of the completed assembly of the housing and rear cover.
Figure 7 is a side view of Figure 6.
Figure 8 is a diagram showing a conductor bar installed inside the rear cover.
Figure 9 is a diagram for explaining the guide groove of the ground bearing.
Figure 10 is a cross-sectional perspective view before assembly of the housing and rear cover.
Figure 11 is a cross-sectional perspective view of the completed assembly of the housing and rear cover.
Figure 12 is a side view of Figure 11.

Hereinafter, the present invention will be described with reference to the attached drawings.

Figure 2 is an exploded perspective view of a motor according to an example of the present invention, and Figure 3 is a view viewed from the opposite direction of Figure 2. As shown, the motor 1 of the present invention largely consists of a housing 10 and a rear cover ( 20), and a grounding structure 30.

The housing 10 is a cover member that accommodates various components of the motor, and a stator, a rotor, a shaft 11, and a drive bearing 12 can be accommodated inside the housing 10. The stator is disposed on the outermost side of the housing, a rotor is disposed inside the stator, a shaft 11 is disposed inside the rotor, and a drive bearing 12 is disposed on the shaft to support the shaft (Figure 1 , 4). The shaft 11 may be a hollow shaft or a solid shaft, and in the case of a solid shaft, a groove may be formed in the center of the shaft, and a hollow 11C may be formed along the axial direction in the center of the shaft 11. You can.

The rear cover 20 is a cover member that is coupled to the rear of the housing 10 and closes the open rear portion of the housing 10. The rear cover 20 is made of a metal material and may be grounded.

The grounding structure 30 is configured to ground the shaft 11. The present invention relates to an electrostatic prevention structure for a motor. By grounding the shaft 11 through the grounding structure 30, it is possible to prevent electric corrosion of the drive bearing due to axial current flowing through the shaft 11.

Referring again to FIGS. 2 and 3, the grounding structure 30 of the present invention includes a grounding bearing 100 and a conductor bar 200, and further includes a fixing member 300.

The ground bearing 100 includes an inner ring, an outer ring, and a bearing ball interposed between the inner ring and the outer ring, and may be filled with grease inside. The conductor bar 200 is a conductive member and, for example, may be made of a metal material. The fixing member 300 is a member for fixing the conductor bar 200 and may be a bolt, for example.

In the grounding structure 30 of the present invention, the ground bearing 100 is inserted into the hollow 11C of the shaft at the rear end side of the shaft 11, and one side of the conductor bar 200 is attached to the rear cover 20. It is fixed and has a structure in which the other side is in contact with the ground bearing 100. That is, the ground bearing 100 and the rear cover 20 are electrically connected through the conductor bar 200, and the ground bearing 100 is electrically connected to the shaft 11, so that the shaft 11 and the rear cover ( 20) are connected to each other, and the shaft 11 electrically connected to it is finally grounded by the grounded rear cover 20.

In this way, the shaft 11 and the rear cover 20 are electrically connected through the grounding structure 30, thereby creating a new path through which the axial current on the shaft is transmitted to the housing (including the rear cover), which is different from the existing path. It forms a parallel structure with the current path passing through the drive bearing. Accordingly, the axial current of the shaft is distributed and transmitted to the rear cover 20 through the grounding structure 30, thereby reducing the amount of current passing through the drive bearing, thereby preventing corrosion in the drive bearing.

In other words, according to the present invention, by preventing electrostatic corrosion in the driving bearing, the loss of the driving bearing due to electrostatic corrosion can be reduced, the vibration and noise generated in the driving bearing due to the electrostatic phenomenon can be reduced, and furthermore, it is possible to prevent conventional electrostatic corrosion. For this reason, the use of ceramic balls can be converted to steel balls, thereby reducing the manufacturing cost of the motor.

Hereinafter, the grounding structure 30 of the present invention will be examined in more detail through specific embodiments.

Figure 4 is a cross-sectional perspective view before assembly of the housing and rear cover, Figure 5 is a side view of Figure 4, Figure 6 is a cross-sectional perspective view after assembly of the housing and rear cover is completed, and Figure 7 is a side view of Figure 6. This is a view as seen, and Figure 8 is a view showing a conductor bar installed inside the rear cover.

First, the ground bearing 100 is press-fitted into the hollow 11C of the shaft 11, so that the outer ring 120 of the ground bearing is in close contact with the inner peripheral surface of the shaft 11. For example, the diameter of the ground bearing 100 is formed to be larger than or equal to the diameter of the hollow 11C of the shaft, so that the ground bearing 100 can be mid-fitted or pressed into the hollow 11C of the shaft. there is. Accordingly, the shaft and the ground bearing are tightly coupled, and connectivity between the shaft and the ground bearing can be secured.

Then, the conductor bar 200 is in contact with the inner ring 110 of the ground bearing. At this time, the conductor bar 200 is structured to press the inner ring 110 of the ground bearing radially outward, which can increase the load capacity of the inner ring 110 of the ground bearing, and accordingly, the bearing balls 130 and The inner and outer rings 110 and 120 are brought into closer contact so that constant connectivity can be secured.

More specifically, referring to FIG. 7, the conductor bar 200 includes a fixing part 210 fixed to the rear cover 20, and a protrusion 220 extending from the fixing part 210 and protruding toward the shaft 11. ), and at least a portion of the protrusion 220 is inserted into the hollow 11C of the ground bearing and comes into contact with the outer peripheral surface of the inner ring 110 of the ground bearing. At this time, the protrusion 220 of the breech is press-fitted into the hollow 100C of the ground bearing. That is, the maximum diameter of the protrusion 220 of the conductor bar is formed to be larger than the diameter of the hollow 100C of the ground bearing, so that the protrusion 220 of the conductor bar is press-fitted into the hollow 100C of the bearing, and accordingly, the inner ring of the ground bearing (110) can be pressed radially outward.

As a specific example of a conductor bar that performs this function, referring to FIGS. 5 to 8, the conductor bar 200 of this example is a bar member bent in a U shape, and the central portion is formed in a ring shape to form the inner ring of the ground bearing ( 110), and both ends are respectively fixed to the rear cover 20.

At this time, if the part of the protruding part 220 of the conductor bar inserted into the hollow of the ground bearing is called the head part 220H, and the remaining part excluding the head part 220H is called the body part 220B, as shown, the head part 220B The portion 220H is formed in a ring shape, and the body portion 220B is formed narrowly. Here, the conductor bar 200 of this example may have a predetermined elasticity, and has a structure in which the head portion 220H is expanded by forming the body portion 220B narrowly, so that the pressing force on the inner ring 110 will increase. You can. In addition, the structure of the conductor bar 200 is very simple and has the advantage of being convenient to manufacture and install.

Figure 9 is a diagram for explaining the guide groove of the ground bearing. As shown, a guide groove 110G is formed on the outer peripheral surface of the inner ring 110 of the ground bearing and is predeterminedly indented inward, and a conductor is placed in the guide groove 110G. As the portion of the protrusion 220 of the bar that is in contact with the inner ring 110 of the ground bearing is seated and fixed, the conductor bar 200 can be prevented from slipping on the inner ring 110. The guide groove 110G has a structure that is recessed in the axial direction at a specific position (for example, a position corresponding to the conductor bar) on the outer circumferential surface of the inner ring 110, or is recessed in the radial direction on the outer circumferential surface of the inner ring 110. It can be formed in the form of a ring groove. In addition, the part of the protrusion 220 of the conductor bar that is in contact with the inner ring 110 has a flat structure so as to be in close contact with the outer peripheral surface of the inner ring 110, so that the contact area with the inner ring is increased, thereby improving the connection between the inner ring and the conductor bar. At the same time, it is firmly seated in the guide groove, so the fixing force between the bearing and the conductor bar and the pressing force of the conductor bar toward the bearing can be increased.

Figures 10 to 12 are views showing other embodiments of the conductor bar, Figure 10 is a cross-sectional perspective view before assembly of the housing and rear cover, Figure 11 is a cross-sectional perspective view after assembly of the housing and rear cover, and Figure 12 is a This is a view of number 11 from the side.

As shown, the conductor bar 200 of this example has a protruding spherical structure. More specifically, the part of the protrusion 220 of the conductor bar that is inserted into the hollow 100C of the ground bearing 100 is called the head 220H, and the remaining part excluding the head 220H is called the body 220B. In this case, the head portion 220H is formed in a spherical shape, and the body portion 220B is formed narrowly. The side cross-sectional shape of the conductor bar 200 in this example is substantially the same as the side cross-sectional shape of the conductor bar 200 in the previous example, and the operating principle thereof may also be the same. However, the conductor bar 200 of the present example is formed in a spherical shape, and as the contact area with the inner ring 110 of the ground bearing increases, the pressing force on the inner ring further increases compared to the conductor bar 200 of the previous example. , there is an advantage that constant connectivity between the conductor bar 200 and the bearing 100 is improved.

In addition, as shown in FIG. 10, a guide groove 110G is formed on the outer peripheral surface of the inner ring 110 of the ground bearing of this example, and is indented to the inside, and the protrusion 220 of the conductor bar is formed in the guide groove 110G. can be settled. This performs the same function as the guide groove described in FIG. 9. In this case, the groove shape of the guide groove 110G in this example is formed to correspond to the shape of the portion in contact with the inner ring 110 among the protrusions 220 of the conductor bar. You can.

Meanwhile, as described above, the grounding structure 30 of the present invention includes a fixing member 300, and the conductor bar 200 can be fixed to the rear cover 20 by the fixing member 300. Member 300 may be a bolt. Referring again to FIGS. 7 and 12, the conductor bar 200 may be bolted to the rear cover 20. More specifically, as the fixing part 210 corresponding to the rear cover 20 side end of the conductor bar 200 is bolted to the rear cover 20 by the bolt 300, the conductor bar 200 is rear It can be installed and fixed to the cover 20. Through this bolting combination, the conductor bar can be easily and simply fixed to the rear cover, and at the same time, an electrical connection between the conductor bar and the rear cover can be secured. Furthermore, the conductor bar can be installed on the rear cover as is without changing the design of the rear cover of the existing motor. There are benefits to this.

And, as described above, the inside of the ground bearing 100 may be filled with grease for lubrication between the bearing balls 130 and the inner and outer rings 110 and 120. At this time, the grease may be a conductive grease with current conductivity, which can improve the electrical connection between the bearing balls and the inner and outer rings.

Furthermore, as described above, a drive bearing 12 supporting the shaft 11 is installed on the shaft 11, and at this time, the motor 1 of the present invention flows the shaft current through the ground structure 30 to As the amount of current flowing to the drive bearing side is reduced, the electrostatic phenomenon on the drive bearing side is reduced, so even if the bearing balls of the drive bearing are made of steel balls, damage to the drive bearing due to electrocorrosion does not occur. That is, the bearing balls of the drive bearing of the motor of the present invention may be composed of steel balls, which are cheaper than ceramic ball bearings and can reduce the overall manufacturing cost of the motor.

Above, embodiments of the present invention have been described with reference to the attached drawings, but those skilled in the art will understand that the present invention can be implemented in other specific forms without changing the technical idea or essential features. You will understand that it exists. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

1: motor
10: Housing
11: shaft
11C: hollow of shaft
12: Drive bearing
20: Rear cover
30: Ground structure
100: ground bearing
100C: Hollow in ground bearing
110: inner ring
120: paddle
130: bearing ball
200: conductor bar
210: Fixing part of conductor bar
220: Protrusion of conductor bar
300: Fixing member

Claims (12)

A housing that accommodates a stator, a rotor disposed inside the stator, and a shaft disposed inside the rotor;
A rear cover coupled to the rear of the housing; and
Includes a grounding structure for grounding the shaft,
The grounding structure is
A ground bearing inserted into the hollow of the shaft,
Comprising a conductor bar whose one side is fixed to the rear cover and whose other side is in contact with the ground bearing,
Electrostatic prevention structure of the motor.
According to paragraph 1,
The ground bearing is press-fitted into the hollow of the shaft so that the outer ring of the ground bearing is in close contact with the inner peripheral surface of the shaft,
The conductor bar is in contact with the inner ring of the ground bearing,
Electrostatic prevention structure of the motor.
According to paragraph 2,
The conductor bar includes a fixing part fixed to the rear cover, and a protrusion extending from the fixing part and protruding toward the shaft,
At least a portion of the protrusion is inserted into the hollow of the ground bearing and contacts the outer peripheral surface of the inner ring of the ground bearing,
Electrostatic prevention structure of the motor.
According to paragraph 3,
The protrusion of the conductor bar is press-fitted into the hollow of the ground bearing and has a structure to press the inner ring of the ground bearing radially outward,
Electrostatic prevention structure of the motor.
According to paragraph 4,
The conductor bar is a rod member bent in a U-shape, the central part of which is formed in a ring shape and is in contact with the inner ring of the ground bearing, and both ends are respectively fixed to the rear cover,
Electrostatic prevention structure of the motor.
According to clause 5,
Among the protrusions of the conductor bar, the part inserted into the hollow of the ground bearing is called the head, and the remaining part excluding the head is called the body,
The head has a ring shape,
The body portion is formed narrowly,
Electrostatic prevention structure of the motor.
According to paragraph 4,
The conductor bar is composed of a protruding spherical structure,
Electrostatic prevention structure of the motor.
In clause 7,
Among the protrusions of the conductor bar, the part inserted into the hollow of the ground bearing is called the head, and the remaining part excluding the head is called the body,
The head has a spherical shape,
The body portion is formed narrowly,
Electrostatic prevention structure of the motor.
According to paragraph 3,
On the outer peripheral surface of the inner ring of the ground bearing, a guide groove is formed with a predetermined indentation inward so that the portion of the protrusion of the conductor bar that is in contact with the inner ring of the ground bearing can be seated,
Electrostatic prevention structure of the motor.
According to paragraph 1,
The conductor bar is bolted to the rear cover,
Electrostatic prevention structure of the motor.
According to paragraph 1,
The interior of the ground bearing is filled with conductive grease,
Electrostatic prevention structure of the motor.
According to paragraph 1,
The housing further accommodates a drive bearing installed on the shaft to support the shaft,
The bearing balls of the drive bearing are composed of steel balls,
Electrostatic prevention structure of the motor.