A motor insulation bearing voltage division measuring device

Abstract

The application discloses a motor insulating bearing voltage sharing measurement device, which comprises a main shaft, an inner bearing cover, an end cover and a speed measurement tooth disc outer cover. The main shaft is installed in the inner bearing cover through an insulating bearing. The insulating bearing comprises an inner ring, an outer ring and an insulating layer arranged on the outer ring. The end cover is connected with the inner bearing cover. The speed measurement tooth disc outer cover is connected with the end cover. The measurement device further comprises a conductive disc, an electric brush, a first leading wire, a second leading wire, a third leading wire and a detection module. The conductive disc is arranged on the main shaft and contacts the inner ring. The electric brush is arranged in the speed measurement tooth disc outer cover and contacts the conductive disc. The first leading wire is connected with the inner bearing cover. The second leading wire is connected with the outer ring. The third leading wire is connected with the electric brush. The motor insulating bearing voltage sharing measurement device can not only measure the shaft voltage of the motor main shaft, but also measure the voltage shared by the insulating layer of the insulating bearing, so that the voltage sharing ratio of the insulating layer of the insulating bearing is obtained.

Description

Technical Field

[0001] This application relates to the field of motor testing technology, and in particular to a motor insulation bearing voltage divider measuring device. Background Technology

[0002] Currently, the motor drive system uses a power converter with pulse width modulation (PWM) technology. This power converter has advantages such as wide speed range and fast dynamic response. However, the IGBT high-speed switching devices used in the system will generate high-frequency common-mode voltage. This common-mode voltage generates shaft voltage and shaft current through the motor shaft, leading to electro-corrosion of the motor bearing. The severe electro-corrosion of the bearing severely restricts the service life of the subway traction motor bearing. There are three main methods to reduce the shaft voltage: (1) using hybrid ceramic insulated bearings; (2) increasing the insulation layer thickness; (3) short-circuiting the shaft current. The first two methods mainly reduce the shaft voltage by increasing the insulation impedance of the bearing, thereby reducing the shaft current. To evaluate the voltage dividing capacity of the insulated bearing, it is necessary to measure the shaft voltage of the motor and the voltage dividing ratio of the insulation layer of the insulated bearing.

[0003] Existing bearing electro-corrosion testing devices and methods primarily measure the actual shaft voltage of traction motor bearings during online operation, or simulate the actual operation of traction motor bearings through bearing bench tests and apply shaft voltage to the bearings to analyze the relationship between different shaft voltages and the degree of bearing electro-corrosion. However, existing bearing electro-corrosion testing devices and methods cannot measure the voltage division ratio of the insulation layer of traction motor insulated bearings. Therefore, it is necessary for those skilled in the art to provide a measuring device and method capable of measuring the voltage division ratio of the insulation layer of traction motor insulated bearings. Summary of the Invention

[0004] The purpose of this application is to provide a voltage divider measuring device for motor insulated bearings, which can not only measure the shaft voltage of the motor spindle, but also measure the voltage shared by the insulation layer of the insulated bearing, thereby obtaining the voltage divider ratio of the insulation layer of the insulated bearing.

[0005] To achieve the above objectives, this application provides a motor insulated bearing voltage divider measuring device, including a main shaft, an inner bearing cover, an end cover, and a speed measuring gear outer cover. The main shaft is installed in the inner bearing cover via an insulated bearing, which includes an inner ring, an outer ring, and an insulating layer disposed on the outer ring. The end cover is connected to the inner bearing cover, and the speed measuring gear outer cover is connected to the end cover.

[0006] It also includes a conductive disk, a brush, a first lead wire, a second lead wire, a third lead wire, and a detection module. The conductive disk is located on the main shaft and contacts the inner ring. The brush is located inside the outer cover of the speed measuring gear and contacts the conductive disk. The first lead wire is connected to the inner bearing cover, the second lead wire is connected to the outer ring, and the third lead wire is connected to the brush.

[0007] When measuring the spindle voltage, one input terminal of the detection module is connected to the first lead, and the other input terminal is connected to the third lead. When measuring the voltage shared by the insulation layer, one input terminal of the detection module is connected to the first lead, and the other input terminal of the detection module is connected to the second lead.

[0008] In some embodiments, the first lead wire is connected to the outer diameter surface of the inner bearing cap via a detachable connector.

[0009] In some embodiments, the inner bearing cover is provided with a first lead-out hole, and the end cover is provided with a second lead-out hole. The second lead-out hole communicates with the first lead-out hole, and the first lead-out wire is connected to the outer diameter surface of the inner bearing cover and led out through the first lead-out hole and the second lead-out hole.

[0010] In some embodiments, the outer ring is provided with a connecting hole, the end cap is provided with a third lead-out hole, the outer cover of the speed measuring gear is provided with a fourth lead-out hole, and the second lead-out wire is connected to the connecting hole and led out through the third lead-out hole and the fourth lead-out hole.

[0011] In some embodiments, an insulating sleeve is also included, which is fixed to the outer cover of the speed measuring gear, and the brush is installed at the bottom of the insulating sleeve.

[0012] In some embodiments, an insulating cover plate is also included, which is disposed on the insulating sleeve and has a through hole for leading out the third lead wire.

[0013] In some embodiments, an elastic element is also included, which abuts between the insulating cover and the brush, and the elastic element is used to provide an elastic force to the brush, causing the brush to tend to move away from the insulating cover.

[0014] In some embodiments, the spindle is provided with a shoulder, the inner bearing cover is provided with a mounting step, the two end faces of the inner ring contact the shoulder and the conductive disk respectively, and the two end faces of the outer ring contact the mounting step and the end cover respectively.

[0015] In some embodiments, the conductive disk has a groove on the side near the insulating bearing, the groove being used to accommodate the spindle.

[0016] In some embodiments, the inner side of the outer cover of the speed measuring gear is provided with a clearance groove, which is used to avoid the conductive disk when the conductive disk rotates with the spindle.

[0017] Compared to the aforementioned background technology, the motor insulated bearing voltage divider measuring device provided in this application includes a main shaft, an inner bearing cover, an end cover, and a speed measuring gear outer cover. The main shaft is mounted inside the inner bearing cover via an insulated bearing, which includes an inner ring, an outer ring, and an insulating layer disposed on the outer ring. The end cover is connected to the inner bearing cover, and the speed measuring gear outer cover is connected to the end cover. Further, the measuring device also includes a conductive disk, a brush, a first lead wire, a second lead wire, a third lead wire, and a detection module. The conductive disk is disposed on the main shaft and contacts the inner ring. The brush is disposed inside the speed measuring gear outer cover and contacts the conductive disk. The first lead wire is connected to the inner bearing cover, the second lead wire is connected to the outer ring, and the third lead wire is connected to the brush. Thus, when measuring the shaft voltage of the main shaft, one input terminal of the detection module is connected to the first lead wire, and the other input terminal is connected to the third lead wire. When measuring the voltage shared by the insulating layer, one input terminal of the detection module is connected to the first lead wire, and the other input terminal is connected to the second lead wire. In other words, by measuring the voltage between the first and third leads, the shaft voltage of the motor spindle can be measured. By measuring the voltage between the first and second leads, the voltage borne by the insulation layer of the insulated bearing can be measured. Finally, the ratio of the voltage borne by the insulation layer of the insulated bearing to the shaft voltage can be calculated, and this ratio is the voltage division ratio of the insulation layer of the insulated bearing. Compared with traditional measuring devices that cannot measure the voltage division ratio of the insulation layer of a motor insulated bearing, the motor insulated bearing voltage division measuring device provided in this application, through structural modification of an existing motor, simulates the actual operating conditions of the motor by applying voltages of different magnitudes and frequencies to the bearing unit. It can not only measure the shaft voltage of the motor spindle, but also measure the voltage borne by the insulation layer of the insulated bearing, thereby obtaining the voltage division ratio of the insulation layer (or common-mode voltage) of the insulated bearing. This is beneficial for evaluating the voltage division capability of the insulated bearing and analyzing the relationship between the insulation impedance and bearing electro-corrosion, and can thus improve the service life of the motor bearing to a certain extent. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of the motor insulation bearing voltage divider measuring device in the embodiments of this application.

[0020] in:

[0021] 1-Main spindle; 2-Inner bearing cover; 21-Outer diameter surface; 22-First lead-out hole; 23-Mounting step; 3-Insulated bearing; 31-Inner ring; 32-Outer ring; 33-Insulation layer; 4-First bolt; 5-End cover; 51-Second lead-out hole; 52-Third lead-out hole; 6-Third lead wire; 7-Insulating cover plate; 8-Elastic element; 9-Insulating sleeve; 10-Brush; 11-Conductive disk; 111-Groove; 12-Second bolt; 13-Tachymeter gear outer cover; 131-Fourth lead-out hole; 132-Allowing groove; 14-Second lead wire; 15-First lead wire; 16-Detachable connector. Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] It should be noted that the directional terms such as "upper end," "lower end," "left side," and "right side" mentioned below are defined based on the accompanying drawings in the instruction manual.

[0025] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of the motor insulation bearing voltage divider measuring device in the embodiments of this application.

[0026] The motor insulated bearing voltage divider measuring device provided in this application embodiment includes a main shaft 1, an inner bearing cover 2, an end cover 5, and a speed measuring gear outer cover 13. The inner bearing cover 2, the end cover 5, and the speed measuring gear outer cover 13 are all located at the non-transmission end of the main shaft 1. The main shaft 1 is installed in the inner bearing cover 2 through an insulated bearing 3. The insulated bearing 3 includes an inner ring 31, an outer ring 32, and an insulating layer 33 located on the outer ring 32. The insulating layer 33 is used to improve the insulation resistance of the bearing to reduce the degree of electrical corrosion of the bearing. The end cover 5 is connected to the inner bearing cover 2, and the speed measuring gear outer cover 13 is connected to the end cover 5.

[0027] Of course, depending on actual needs, the outer cover 13 of the speed measuring gear, the end cover 5 and the inner bearing cover 2 can be connected by the first bolt 4, which is set parallel to the axis of the main shaft 1.

[0028] Furthermore, the measuring device also includes a conductive disk 11, a brush 10 (or a carbon brush), a first lead wire 15, a second lead wire 14, a third lead wire 6, and a detection module. The conductive disk 11 is mounted on the spindle 1 and contacts the inner ring 31. The brush 10 is mounted inside the outer cover 13 of the speed measuring gear and contacts the conductive disk 11. The first lead wire 15 is connected to the inner bearing cover 2, the second lead wire 14 is connected to the outer ring 32, and the third lead wire 6 is connected to the brush 10.

[0029] In some embodiments, in order to facilitate axial positioning of the bearing, the spindle 1 is provided with a shoulder, the inner bearing cover 2 is provided with a mounting step 23, the two end faces of the inner ring 31 contact the shoulder and the conductive disk 11 respectively, and the two end faces of the outer ring 32 contact the mounting step 23 and the end cover 5 respectively, so as to achieve axial positioning of the bearing.

[0030] In some embodiments, the conductive disk 11 has a groove 111 on the side near the insulating bearing 3, the groove 111 being used to accommodate the spindle 1. Specifically, the conductive disk 11 can be connected to the end of the spindle 1 by a second bolt 12. The groove 111 is provided to improve the stability and reliability of the connection between the conductive disk 11 and the spindle 1, and to ensure that the two rotate synchronously.

[0031] In some embodiments, the inner side of the speed measuring gear cover 13 is provided with a relief groove 132, which is used to avoid the conductive disk 11 when it rotates with the main shaft 1. The relief groove 132 can be an annular relief groove 132, so that when the conductive disk 11 rotates with the main shaft 1, the speed measuring gear cover 13 can prevent the conductive disk 11 from interfering with the conductive disk 11, and ensure the stability of the rotation of the conductive disk 11.

[0032] In this way, when measuring the shaft voltage of the main spindle 1, one input terminal of the detection module is connected to the first lead 15, and the other input terminal is connected to the third lead 6. When measuring the voltage shared by the insulation layer 33, one input terminal of the detection module is connected to the first lead 15, and the other input terminal is connected to the second lead 14. That is, by measuring the voltage between the first lead 15 and the third lead 6, the shaft voltage of the motor main spindle 1 can be measured. By measuring the voltage between the first lead 15 and the second lead 14, the voltage borne by the insulation layer 33 of the insulating bearing 3 can be measured. Finally, the ratio of the voltage borne by the insulation layer 33 of the insulating bearing 3 to the shaft voltage is calculated. This ratio is the voltage division ratio of the insulation layer 33 of the insulating bearing 3.

[0033] Of course, the detection module can be a voltmeter or other instrument capable of measuring voltage.

[0034] Compared to traditional measuring devices that cannot measure the voltage division ratio of the insulation layer 33 of the motor insulated bearing 3, the motor insulated bearing voltage division measuring device provided in this application embodiment modifies the structure of an existing motor. By applying voltages of different magnitudes and frequencies to the bearing unit, it simulates the actual operating conditions of the motor. It can not only measure the shaft voltage of the motor spindle 1, but also measure the voltage shared by the insulation layer 33 of the insulated bearing 3, thereby obtaining the voltage division ratio of the insulation layer 33 (or common mode voltage) of the insulated bearing 3. This is beneficial for evaluating the voltage division capability of the insulated bearing 3 and analyzing the relationship between the insulation impedance and the bearing electro-corrosion, which can improve the service life of the motor bearing to a certain extent.

[0035] In some embodiments, the first lead wire 15 is connected to the outer diameter surface 21 of the inner bearing cover 2 via a detachable connector 16. The detachable connector 16 can be a bolt or a screw.

[0036] Specifically, the outer diameter surface 21 of the inner bearing cover 2 is provided with a threaded hole. The first lead wire 15 is wound around a bolt or screw, and then the bolt or screw is threaded to the threaded hole on the outer diameter surface 21 of the inner bearing cover 2, so that the first lead wire 15 can be fixed on the outer diameter surface 21 of the inner bearing cover 2.

[0037] In some embodiments, the inner bearing cover 2 is provided with a first outlet hole 22, and the end cover 5 is provided with a second outlet hole 51. The second outlet hole 51 can be a grease filling channel for the end cover 5. The second outlet hole 51 is connected to the first outlet hole 22. The first lead wire 15 is connected to the outer diameter surface 21 of the inner bearing cover 2 and leads out through the first outlet hole 22 and the second outlet hole 51.

[0038] In this way, the first lead 15 can be used as the first test point, and the potential of the outer ring 32 of the insulating bearing 3 can be measured at the first test point.

[0039] In some embodiments, the outer ring 32 of the insulating bearing 3 has a connecting hole on its flange, the end cover 5 has a third lead-out hole 52, and the outer cover 13 of the speed measuring gear has a fourth lead-out hole 131. The second lead-out wire 14 is connected to the connecting hole on the flange of the outer ring 32 and leads out through the third lead-out hole 52 and the fourth lead-out hole 131. Of course, the second lead-out wire 14 can be fixed in the connecting hole by adhesive bonding.

[0040] In this way, the second lead 14 can be used as the second test point, and the potential of the inner raceway surface of the outer ring 32 of the insulating bearing 3 can be measured at the second test point.

[0041] In some embodiments, to facilitate the assembly of the brush 10, the measuring device further includes an insulating sleeve 9, which is fixed to the outer cover 13 of the speed measuring gear, and the brush 10 is installed at the bottom of the insulating sleeve 9 and extends out of the bottom of the insulating sleeve 9.

[0042] In some embodiments, the measuring device further includes an insulating cover plate 7, which is fixedly connected to the insulating sleeve 9. The insulating cover plate 7 has a through hole for the third lead wire 6 to be led out.

[0043] In some embodiments, to ensure that the brush 10 and the conductive disk 11 are always in contact, the measuring device further includes an elastic element 8, which abuts against the insulating cover plate 7 and the brush 10. The elastic element 8 is used to provide an elastic force to the brush 10, causing the brush 10 to tend to move away from the insulating cover plate 7. Of course, the elastic element 8 is a compression spring.

[0044] In this way, the third lead wire 6 is connected to the spring and the brush 10. The brush 10 is fixed inside the outer cover 13 of the speed measuring gear plate through the insulating sleeve 9. After the insulating cover plate 7 presses the spring, it ensures that the brush 10 is in close contact with the conductive disk 11. The third lead wire 6 is led out through the through hole on the insulating cover plate 7.

[0045] The third lead-out line 6 can be used as the third test point, and the potential on the motor shaft side can be measured at the third test point.

[0046] It is understandable that the voltage measured at the first and third test points is the shaft voltage. Since the lead at the first test point is closer to the bearing, the shaft voltage measured at the first test point is more accurate. The voltage measured at the first and second test points is the voltage shared by the insulating layer 33 of the insulating bearing 3.

[0047] In addition, the voltages at the second and third test points can be measured. The measured voltages are the voltages shared by the oil film in the insulating bearing 3, which is the oil film between the outer ring 32 and the rolling elements. This allows for the calculation of the voltage division ratio of the oil film within the insulating bearing 3, which is beneficial for evaluating the voltage division capability of the insulating bearing 3 and analyzing the relationship between the bearing's insulation impedance and bearing electro-corrosion. Consequently, it can improve the service life of the motor bearing to a certain extent.

[0048] It should be noted that the above-mentioned measuring device can easily and accurately measure the shaft voltage and the voltage shared by the insulating bearing 3 without modifying the motor structure, thereby obtaining the voltage division ratio of the common mode voltage of the insulating bearing 3. At the same time, by combining the measurement of the voltage division ratio of the insulating layer 33 of the insulating bearing 3 and the voltage division ratio of the oil film inside the insulating bearing 3, the calculation accuracy of the voltage division capability of the insulating bearing 3 can be improved, and the relationship between the insulation impedance of the bearing and the bearing electro-corrosion obtained by this method is more reliable.

[0049] It should be noted that in this specification, relational terms such as first and second are used only to distinguish one entity from several other entities, and do not necessarily require or imply any such actual relationship or order between these entities.

[0050] The above provides a detailed description of the motor insulation bearing voltage divider measuring device provided in this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are merely for the purpose of helping to understand the solution and core ideas of this application. It should be noted that those skilled in the art can make various improvements and modifications to this application without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A voltage divider measuring device for motor insulated bearings, characterized in that, The device includes a main shaft, an inner bearing cover, an end cover, and an outer cover for a speed measuring gear. The main shaft is mounted inside the inner bearing cover via an insulated bearing. The insulated bearing includes an inner ring, an outer ring, and an insulating layer disposed on the outer ring. The end cover is connected to the inner bearing cover, and the outer cover for the speed measuring gear is connected to the end cover. It also includes a conductive disk, a brush, a first lead wire, a second lead wire, a third lead wire, and a detection module. The conductive disk is disposed on the main shaft and contacts the inner ring. The brush is disposed inside the outer cover of the speed measuring gear and contacts the conductive disk. The first lead wire is connected to the inner bearing cover. The second lead wire is connected to the outer ring. The third lead wire is connected to the brush. When measuring the spindle's shaft voltage, one input terminal of the detection module is connected to the first lead, and the other input terminal is connected to the third lead. When measuring the voltage shared by the insulation layer, one input terminal of the detection module is connected to the first lead, and the other input terminal is connected to the second lead. It also includes an insulating sleeve, which is fixed to the outer cover of the speed measuring gear, and the brush is installed at the bottom of the insulating sleeve; It also includes an insulating cover plate, which is disposed on the insulating sleeve and has a through hole for the third lead wire to be led out. It also includes an elastic element that abuts between the insulating cover and the brush, the elastic element being used to provide an elastic force to the brush, causing the brush to tend to move away from the insulating cover; The inner side of the outer cover of the speed measuring gear is provided with a clearance groove, which is used to avoid the conductive disk when the conductive disk rotates with the main shaft.

2. The motor insulation bearing voltage divider measuring device as described in claim 1, characterized in that, The first lead wire is connected to the outer diameter surface of the inner bearing cover via a detachable connector.

3. The motor insulation bearing voltage divider measuring device as described in claim 2, characterized in that, The inner bearing cover is provided with a first lead-out hole, and the end cover is provided with a second lead-out hole. The second lead-out hole communicates with the first lead-out hole, and the first lead-out wire is connected to the outer diameter surface of the inner bearing cover and leads out through the first lead-out hole and the second lead-out hole.

4. The motor insulation bearing voltage divider measuring device as described in claim 1, characterized in that, The outer ring is provided with a connecting hole, the end cover is provided with a third lead-out hole, the outer cover of the speed measuring gear is provided with a fourth lead-out hole, and the second lead-out wire is connected to the connecting hole and led out through the third lead-out hole and the fourth lead-out hole.

5. The motor insulation bearing voltage divider measuring device as described in any one of claims 1-4, characterized in that, The main shaft is provided with a shoulder, the inner bearing cover is provided with a mounting step, the two end faces of the inner ring respectively contact the shoulder and the conductive disk, and the two end faces of the outer ring respectively contact the mounting step and the end cover.

6. The motor insulation bearing voltage divider measuring device as described in claim 1, characterized in that, The conductive disk has a groove on the side near the insulating bearing, and the groove is used to accommodate the spindle.

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