CN202178665U - Current eliminating device of motor shaft - Google Patents

Abstract

The utility model is a current elimination device for a motor shaft. One end of a cylindrical bracket sleeved on the motor shaft is fixed to a bearing pressure plate or a motor end cover, and a brush assembly is fixed to a radial hole on one side of the bracket. The bottom of the conductive tube brush rod of the brush assembly is a carbon brush, and the sleeve sleeve is bonded and fixed on the upper part of the brush rod. One end of the connecting piece is inserted into the opening groove at the upper end of the brush rod, and the nut is screwed on the upper end of the brush rod to compress and fix the connecting piece. The compression spring is between the connecting piece and the carbon brush. The bushing is fixed to the radial hole of the bracket, the brush rod and the carbon brush are inserted into the hole, and the compression spring presses the bottom end of the carbon brush to protrude from the brush rod to make good contact with the motor shaft. The binding post connecting the outer end of the chip is grounded through the lead wire. The carbon brush guides the shaft current of the motor shaft to the connecting piece through the brush rod, and the grounding is eliminated. There are insulation bonding material layers between the brush rod and the casing, and between the connecting piece and the casing to ensure the insulation of the brush rod, the casing and the connecting piece. The device can completely eliminate the motor shaft current, prolong the service life of the motor bearing, has a simple structure and low cost, and is easy to popularize.

Description

Motor shaft current elimination device

(1) Technical field

The utility model relates to the technical field of motors, in particular to a motor shaft current eliminating device.

(2) Background technology

During the operation of the motor, if there is shaft current at the two bearing ends or between the motor shaft and the bearing, the service life of the motor bearing will be greatly shortened. The bearings will be damaged if the motor runs for thousands of hours with a slight shaft current. If the shaft current is severe, the motor can only run for a few hours. It directly affects safe production, and the direct and indirect economic losses caused by frequent replacement of bearings cannot be subsumed.

The shaft voltage generated between the two bearing ends of the motor or between the motor shaft and the bearing leads to the existence of shaft current. The main causes of shaft voltage are as follows:

(1) Shaft voltage generated by magnetic imbalance

The fan-shaped punching sheets, silicon steel sheets, iron core slots, ventilation holes and other structures stacked in the motor cause unbalanced reluctance in the magnetic circuit of the motor. The rotation of the motor shaft cuts the alternating magnetic flux around it. The shaft voltage is induced at both ends.

(2) Shaft voltage generated by inverter power supply

When the motor is operated with inverter power supply, because the power supply voltage contains higher harmonic components, under the action of the voltage pulse component, electromagnetic induction is generated between the end of the stator winding coil, the wiring part, and the motor shaft, so that the potential of the motor shaft changes, resulting in shaft voltage.

(3) Electrostatic induction generates shaft voltage

There are many high-voltage equipment around the site where the motor is running. Under the action of a strong electric field, the shaft voltage is induced at both ends of the motor shaft.

(4) Intervention of external power supply generates shaft voltage

Due to the complicated wiring of the operation site, especially the protection facilities of large motors and the wiring of measuring components, as long as a live wire end is lapped on the motor shaft, shaft voltage will be generated.

(5) Other reasons

Factors such as the accumulation of static charge and the insulation damage of the temperature measuring element may lead to the generation of shaft voltage.

After the shaft voltage is generated, shaft current is generated once a path is established between the motor shaft and the frame or housing. It can be seen that the generation of shaft current is difficult to avoid, and it can only be drawn out and eliminated by a specially designed device, but there is no device dedicated to eliminating the motor shaft current.

(3) Contents of utility model

The purpose of this utility model is to design a motor shaft current elimination device, which includes a brush directly in contact with the motor shaft to lead the shaft current to ground and eliminate it.

The motor shaft current elimination device designed by the utility model includes a brush assembly and a bracket. The bracket is a cylindrical bracket sleeved on the motor shaft. One end is fixed to the bearing pressure plate or the motor end cover, and there are radial holes on the side. The brush assembly is fixed in the radial hole on one side of the bracket. The brush assembly includes carbon brushes, brush rods, sleeves, compression springs, connecting pieces and nuts. The brush rod is a conductive tube, the carbon brush is located at the bottom of the brush rod, and the sleeve is placed on the upper part of the brush rod, and the two are bonded and fixed. The side wall at the upper end of the brush rod has opposite opening grooves, and one end of the connecting piece is inserted into the opening groove of the brush rod. The upper end of the brush rod is threaded, and the nut is screwed on the upper end of the brush rod to compress and fix the connecting piece. The compression spring is between the connecting piece and the carbon brush. The sleeve is fixed on the radial hole of the bracket, the brush rod and the carbon brush are inserted into the hole, and the pressure spring presses the bottom end of the carbon brush to protrude from the brush rod to make good contact with the motor shaft.

In order to facilitate the extraction of shaft current, the outer end of the connecting piece is equipped with a binding post, and the lead wire is connected to the binding post and the casing, machine base or other grounding places.

The carbon brush leads the shaft current of the motor shaft to the connecting piece through the brush rod, and then the shaft current is grounded and eliminated through the lead wire.

In order to protect the carbon brush from foreign objects affecting its electrical performance, the other end of the bracket is equipped with a protective cover.

In order to prevent the shaft current from flowing back to the motor shaft through the bushing, there is an insulating bonding material layer between the brush rod and the bushing, and between the connecting piece and the bushing to ensure the insulation of the brush rod, the bushing and the connecting piece.

In order to prevent the shaft current from flowing back to the motor shaft through the nut, the nut is an insulating plastic nut.

The advantages of the motor shaft current elimination device of the utility model are: 1. It can completely eliminate the motor shaft current and prolong the working life of the motor bearing; 2. The pressure spring can adjust the pressure of the carbon brush on the motor shaft to ensure good contact, and the influence of the motor efficiency can be reduced. Negligible; 3. Simple structure and low cost, easy to popularize and apply.

(4) Description of drawings

Fig. 1 is the overall structure schematic diagram of the embodiment of this motor shaft current eliminating device;

FIG. 2 is an enlarged schematic view of the brush assembly in FIG. 1 .

The labels in the figure are: 1. Electric brush assembly, 11. Nut, 12. Insulation bonding layer, 13. Compression spring, 14. Brush rod, 15. Carbon brush, 16. Brush braid, 17. Sleeve, 18 . Connecting piece, 19. Terminal post, 2. Protective cover, 3. Motor shaft, 4. Support.

(5) Specific implementation methods

The embodiment of this motor shaft current elimination device is shown in Figure 1, including a brush assembly 1 and a bracket 4, the bracket 4 is a cylindrical bracket sleeved on the motor shaft 3, one end is fixed on the bearing pressure plate or the motor end cover, and the side has a diameter To the hole. The brush assembly 1 is fixed in the radial hole on one side of the bracket 4 . The brush assembly 1 includes a carbon brush 15 , a brush rod 14 , a sleeve 17 , a compression spring 13 , a connecting piece 18 and a nut 11 . The brush rod 14 is a copper pipe, the carbon brush 15 is at the bottom of the brush rod 14, the sleeve 17 is set on the upper part of the brush rod 14, and epoxy resin is cast between the two to form an insulating adhesive layer 12. The side wall at the upper end of the brush rod 14 has a corresponding open groove, and one end of the connecting piece 18 is inserted into the open groove of the brush rod 15 . The nut 11 is screwed on the upper end of the brush rod 15, and the connecting piece 18 is compressed and fixed. The compression spring 13 is located between the connecting piece 18 and the carbon brush 15 . The carbon brush 15 is also connected with a brush braid 16, the brush braid 16 passes through the compression spring 13, the upper end of the brush braid 16 is welded to the connecting piece 18, and the length of the brush braid 16 is 1 mm to 5 mm less than the distance from the bottom surface of the connecting piece 18 to the bottom end of the brush rod 14 . The brush pigtail 16 can be made of conductive material, and also plays the role of drawing the axial current, and can also limit the protruding length of the compression spring 13 . Sleeve 17 is fixed on the radial hole of bracket 4, and the lower part of brush rod 14 and carbon brush 15 are inserted into the hole. Compression spring 13 presses the bottom end of carbon brush 15 to protrude from brush rod 14 to make good contact with motor shaft 3.

The outer end of the connection piece 18 is equipped with a binding post 19, and the lead wire is connected to the binding post and the casing, the machine base or other grounding places.

The other end of the bracket 4 is fitted with the protective cover 2 .

The above-mentioned embodiments are only specific examples for further specifying the purpose, technical solutions and beneficial effects of the utility model, and the utility model is not limited thereto. All modifications, equivalent replacements, improvements, etc. made within the disclosed scope of the present utility model are included in the protection scope of the present utility model.

Claims (5)

1. The motor shaft current elimination device is characterized in that: It includes the brush assembly (1) and the bracket (4). The bracket (4) is a cylindrical bracket set on the motor shaft (3). One end is fixed to the bearing pressure plate or the motor end cover. There are radial holes on the side. The assembly (1) is fixed to the radial hole on one side of the bracket (4); the brush assembly (1) includes a carbon brush (15), a brush rod (14), a sleeve (17), a compression spring (13), connecting piece (18) and nut (11); the brush bar (14) is a conductive tube, the carbon brush (15) is at the bottom of the brush bar (14), and the sleeve (17) is set on the top of the brush bar (14). The upper side wall of the brush rod (14) has a relative opening groove, and one end of the connecting piece (18) is inserted in the opening groove of the brush rod (15), and the upper end of the brush rod (14) is threaded, and the nut ( 11) Screw on the upper end of the brush rod (15), press and fix the connecting piece (18); the pressure spring (13) is between the connecting piece and the carbon brush (15), and the sleeve (17) is fixed on the diameter of the bracket (4). On the hole, the bottom of the brush bar (14) and the carbon brush (15) are inserted in this hole, and the stage clip (13) presses the bottom end of the carbon brush (15) to stretch out the brush bar (14) and contact with the motor shaft (3). 2. The motor shaft current elimination device according to claim 1, characterized in that: The outer end of the connecting piece (18) is equipped with a binding post (19), and the lead wire connects the binding post (19) with the casing, machine base or other grounding places. 3. The motor shaft current elimination device according to claim 1 or 2, characterized in that: The other end of the bracket (4) is equipped with a protective cover (2). 4. The motor shaft current elimination device according to claim 1 or 2, characterized in that: Between the brush rod (14) and the sleeve (17) and between the connecting piece (18) and the sleeve (17), there are insulating adhesive material layers. 5. The motor shaft current elimination device according to claim 1 or 2, characterized in that: Also connected with brush braid (16) on the described carbon brush (15), brush braid (16) passes stage clip (13), and brush braid (16) upper end is welded with connecting piece (18), and the brush braid (16) The length is 1mm-5mm less than the distance from the bottom surface of the connecting piece (18) to the bottom end of the brush rod (14).