Motor shaft voltage testing device

Abstract

The invention discloses a motor shaft voltage testing device, solves the problem of testing difficulty caused by the existence of a coupler at a motor transmission end, is simple and adjustable in structure, can be suitable for a narrow space, and belongs to the technical field of shaft voltage testing devices. The device comprises a data acquisition instrument and an electric brush assembly, a voltage sensor in the data acquisition instrument is connected with the electric brush assembly and a reference ground through electric wires, the electric brush assembly comprises an electric brush box and an electric brush part, the electric brush part is connected with a spring in an insulated mode, and the spring is installed in the electric brush box. The electric brush part slides in the electric brush box through a spring, the electric brush part is connected with an electric wire, and the bottom of the electric brush box is provided with a threading hole for the electric wire to pass through.

Description

Technical Field

[0001] The invention belongs to the technical field of shaft voltage testing devices, and in particular relates to a motor shaft voltage testing device. Background Art

[0002] With the rapid development of high-speed railways, urban rail transit and new energy markets, traction motors, as core components of traction systems, are more widely used. With the development of the market and the competition among various OEMs, high voltage, high frequency and high speed are the main development directions of motors in the future. Due to objective reasons of motor PWM variable frequency control technology, the three-phase input voltage has a phase difference of 120° and is always unbalanced, that is, there is a high common mode voltage at the input end of the motor stator, which will generate a potential difference between the stray capacitances between the various components inside the motor, and then generate shaft voltage acting on both ends of the bearing, causing electrical corrosion of the bearing, thereby reducing the service life of the bearing, and causing bearing peeling, resulting in abnormal noise and large vibration of the motor, which seriously affects the user experience.

[0003] Excessive shaft voltage is the most direct cause of bearing electrocorrosion. In response to the above problem, motor manufacturers and host companies will focus on this issue when conducting motor tests. However, traditional traction motors currently use insulated bearings to prevent electrocorrosion. In order to reduce daily maintenance steps, the motor body does not have an independent brush interface. Therefore, when conducting shaft voltage tests, it is often necessary to modify the motor structure, which is not only time-consuming, but also unable to achieve batch measurement of factory motors. At the same time, bearing electrocorrosion caused by circulating current also requires attention to the potential difference between the two ends of the motor rotor. The current modification plan can only measure the voltage of the rotor at the non-drive end of the motor to the ground, especially after the motor is connected to the gearbox, the space is small, and it is difficult to measure the shaft voltage at the drive end. In addition, the contact area between the test fixture and the motor shaft is small, and the measurement accuracy is low.

[0004] Therefore, the present invention relates to a motor shaft voltage testing device, which is mainly suitable for traction motor shaft voltage detection in the fields of high-speed trains, urban rail trains, new energy vehicles, etc. Its characteristics are that the motor shaft voltage test can be carried out conveniently, quickly and accurately during type tests and routine tests of motor products to confirm the shaft voltage of the motor under different conditions, which is convenient for the subsequent evaluation of the operating reliability of the motor bearings and reduces the risk of bearing electrical corrosion, thereby helping host companies reduce product maintenance costs while ensuring the safe operation of the products.

[0005] In the prior art, the contact surface between the voltage probe and the motor shaft is not controlled, and the contact between the probe and the motor shaft is achieved only through a fixed base. The fixing force during the test has a great influence on the accuracy of the shaft voltage data, and this force is greatly affected by the operator. Excessive adhesion force will lead to increased wear of the brush and even damage to the brush head, while excessive adhesion force will lead to poor contact and distortion of the shaft voltage data. At the same time, the high-density conductive fiber used therein also has the problem of high cost. Summary of the invention

[0006] The purpose of the present invention is to provide a motor shaft voltage testing device, which solves the problem that the motor transmission end is difficult to test due to the existence of a coupling. The device has a simple and adjustable structure and can be used in a small space.

[0007] The present invention is achieved by adopting the following technical solutions: A motor shaft voltage testing device comprises a data acquisition instrument and a brush assembly, wherein a voltage sensor inside the data acquisition instrument is respectively connected to the brush assembly and a reference ground through electric wires, wherein the brush assembly comprises a brush box and a brush part, wherein the brush part is insulated and connected to a spring, wherein the spring is installed in the brush box, wherein the brush part slides in the brush box through the spring, wherein the brush part is connected to the electric wires, and wherein a threading hole for a power supply line to pass through is arranged at the bottom of the brush box.

[0008] When used, the shaft voltage on the motor shaft is introduced into the measurement system through the brush assembly by applying the brush assembly to the motor shaft. The brush assembly is connected to the data acquisition instrument through wires to realize the collection, recording and analysis of the shaft voltage. The brush part can slide in the brush box, which can ensure that the brush part can have good contact with the motor shaft when the motor shaft vibrates, ensuring that the test data is accurate and reliable.

[0009] Further preferably, the spring is a constant force spring, the inner wall of the brush box is provided with a buckle, one end of the constant force spring is connected to the buckle, and the constant force spring can ensure that the brush part and the motor shaft maintain a constant contact pressure at all times.

[0010] Further preferably, the brush part includes a brush body, the contact surface between the brush body and the motor shaft is an arc surface, the brush body is fixedly connected to an insulating brush holder, the insulating brush holder is connected to a spring, and the brush body is connected to an electric wire. The arc surface design can ensure good contact between the brush body and the motor shaft, avoid problems such as temperature increase of the brush assembly, breakage of the brush assembly, poor contact, etc. caused by simple point or line contact, and improve the accuracy of the test results. When the brush part slides in the brush box through the spring, the brush body is always exposed outside the brush box, and during normal sliding, a part of the insulating brush holder is exposed outside the brush box, and a part slides inside the brush box from beginning to end.

[0011] Further preferably, it also includes a connecting piece, which is connected to the outer wall of the brush box. The connecting piece and the brush box are detachably connected, which is not only easy to carry but also can be replaced with a suitable length according to the type of motor.

[0012] Further preferably, the brush assembly further comprises a first brush holder, the first brush holder is arranged between the insulating brush holder and the spring, the first brush holder is arranged as a box body with a threading hole at the bottom, the outer side wall of the first brush holder is arranged with a mounting hole, the insulating brush holder extends into the interior of the first brush holder and is fixedly connected with the first brush holder by means of bolts passing through the mounting hole, so as to ensure that the insulating brush holder and the first brush holder move in unison. The insulating brush holder is provided with a conductor that passes through the insulating brush holder from the top, the brush body is connected to the conductor at the top of the insulating brush holder, the conductor at the bottom of the insulating brush holder is connected to the wire, and the brush body is conveniently replaced by means of bolt connection.

[0013] Further preferably, the connecting piece is connected to a multi-channel component, the multi-channel component is connected to a magnetic base, and the magnetic base is adsorbed on the motor.

[0014] Further preferably, the connecting piece is connected to a mounting bracket, the mounting bracket is installed on the motor process hole, and the brush assembly is installed on the motor process hole or the magnetic base through the rear connecting piece, thereby avoiding damage to the original motor structure, not affecting the factory requirements of the motor, and realizing the test of the motor shaft voltage.

[0015] Further preferably, the brush box is provided with a safety buckle, and the first brush holder is provided with a slide groove cooperating with the safety buckle, the slide groove is arranged along the extension and contraction direction of the spring, and the distance between the bottom of the slide groove and the bottom of the first brush holder is defined as a safety distance, which can avoid the problem of the brush assembly falling off due to abnormal wear. The slide groove can ensure that the brush part will not pop out of the brush box due to excessive wear, and can ensure that the brush body can slide accurately within a certain range.

[0016] Further preferably, one or more safety warning strips are provided on the outer wall of the first brush holder to ensure that the brush body does not have poor contact due to excessive wear. Since the brush body on the first brush holder can be replaced with different models, multiple safety warning strips may be provided in actual use to adapt to different models of brush bodies.

[0017] Further preferably, the data acquisition instrument is provided with a plurality of voltage sensors, each of which is connected to a brush assembly and a reference ground via electric wires. The device has a simple and adjustable structure and can be applied to shaft voltage testing in a narrow space, especially solving the problem of testing difficulty caused by the presence of a coupling at the transmission end of the motor, and facilitating subsequent comparative analysis of shaft voltage data.

[0018] The present invention has the following beneficial effects: 1. The present invention can complete the test of the motor shaft voltage without any modification of the test motor, which is convenient for batch testing of the motor under routine testing.

[0019] 2. The present invention is easy and quick to install, and has low requirements on installation conditions and on-site operators. After the test device is installed, the personnel can stay away from the motor during the test, ensuring the safety of the test personnel.

[0020] 3. The present invention can realize fast and accurate measurement of shaft voltage, which not only helps to evaluate the influence of shaft voltage on bearings, but also facilitates data analysis and accumulation of potential difference at both ends of the motor and voltage at both ends to ground. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 This is one of the schematic diagrams for installing the brush assembly of the present invention; Figure 2 is a cross-sectional schematic diagram of a brush assembly of the present invention; Figure 3 1 is a schematic diagram of the appearance of the first brush holder; Figure 4 It is a schematic diagram of the appearance of the brush box; Figure 5 It is a schematic diagram of the installation position of the conductor; Figure 6 This is the second schematic diagram of the installation of the brush assembly of the present invention.

[0024] In the figure: 1-data acquisition instrument, 2-electric wire, 3-brush assembly, 31-constant force spring, 32-brush box, 321-threading hole, 322-safety buckle, 33-brush body, 34-insulating brush holder, 35-first brush holder, 351-mounting hole, 352-slide groove, 353-safety warning strip, 36-conductor, 4-reference ground, 5-connector, 6-multi-pass assembly, 7-magnetic base, 8-mounting bracket. DETAILED DESCRIPTION

[0025] In order to more clearly understand the above-mentioned objectives, features and advantages of the present invention, the scheme of the present invention will be further described below. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0026] In the description, it should be noted that the terms "first" and "second" are only used for descriptive purposes and should not be understood as indicating or implying relative importance. It should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be internal communication between two elements. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0027] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present invention, rather than all of the embodiments.

[0028] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0029] A motor shaft voltage testing device, embodiment 1 includes a data acquisition instrument 1 and a brush assembly 3, the internal voltage sensor of the data acquisition instrument 1 is connected to the brush assembly 3 and the reference ground 4 through the wire 2, the brush assembly 3 includes a brush box and a brush part, the brush part is insulated and connected with a spring, the spring is installed in the brush box 32, the brush part slides in the brush box 32 through the spring, the brush part is connected to the wire, and the bottom of the brush box 32 is provided with a threading hole 321 for the power supply line 2 to pass through.

[0030] The data acquisition instrument 1 used in this embodiment can be a data acquisition storage device such as an oscilloscope, or a data display instrument such as an oscilloscope, to display the collected signal and automatically / manually complete the data recording work. The grounding terminal of the data acquisition instrument 1 can be directly connected to the earth, or a measuring point of an equivalent ground can be selected according to the test requirements.

[0031] The spring is a constant force spring 31 , and a buckle is provided on the inner wall of the brush box 32 . One end of the constant force spring 31 is connected to the buckle. The constant force spring 31 can ensure that the brush part and the motor shaft always maintain a constant contact pressure.

[0032] The brush part includes a brush body 33, and the contact surface between the brush body 33 and the motor shaft is an arc surface. The brush body 33 is fixedly connected to an insulating brush holder 34, and the insulating brush holder 34 is connected to a spring. The brush body 33 is connected to the wire 2. The brush body 33 selects a suitable arc surface according to the diameter of the test motor shaft to ensure good contact between the brush body 33 and the motor shaft. The brush body 33 can be made of conductive nylon fiber, metal graphite, soft copper and other materials according to actual needs.

[0033] The electric motor also includes a connector 5 connected to an outer wall of a brush box 32. The connector 5 and the brush box 32 are detachably connected, which is not only convenient to carry, but also allows the connector 5 to be replaced with a suitable length according to the type of motor.

[0034] The connecting member 5 used in this embodiment can be a single cylindrical rod, or can be designed as a rectangle or other types according to the external structure of the motor. Its external shape can be linear or in other forms. For example, the connecting member 5 can be designed as a right-angle plate, one end of which is fixed to the brush box 32, and the other end is directly fixed to the motor body by bolts.

[0035] The connector 5 connected below the brush box 32 is detachable from the brush box 32, which is not only convenient for carrying and storage, but also can realize shaft voltage testing of motors of different volumes by combining connectors 5 of different lengths.

[0036] The brush assembly 3 also includes a first brush holder 35, which is arranged between the insulating brush holder 34 and the spring. The first brush holder 35 is arranged as a box body with a threading hole 321 at the bottom. The outer wall of the first brush holder 35 is provided with a mounting hole 351. The insulating brush holder 34 extends into the interior of the first brush holder 35 and is fixedly connected to the first brush holder 35 by means of bolts passing through the mounting hole 351, so as to ensure that the insulating brush holder 34 and the first brush holder 35 move in unison. The insulating brush holder 34 is provided with a conductor 36 that passes through the insulating brush holder 34 from the top. The brush body 33 is connected to the conductor 36 at the top of the insulating brush holder 34, and the conductor 36 at the bottom of the insulating brush holder 34 is connected to the wire 2. The conductor 36 connects the brush body 33 and the wire 2. The wire 2 is responsible for exporting the voltage signal to the data acquisition instrument 1.

[0037] The first brush holder 35 is provided with a mounting hole 351 on the side thereof, and the first brush holder 35 and the insulating brush holder 34 can be fixed together to form a whole by screwing in a slotted headless screw, so as to facilitate the action of the spring.

[0038] The insulating brush holder 34 insulates the brush body 33 from other components to prevent current leakage. The first brush holder 35 is responsible for connecting the insulating brush holder 34 and the spring. On the one hand, it fixes the insulating brush holder 34, and on the other hand, its internal space can prevent the conductor 36 from contacting the outside.

[0039] Here’s how it works: A spring is installed inside the brush box 32 , which can push the brush part against the test shaft of the motor. The brush part introduces the current into the data acquisition instrument 1 through the test shaft.

[0040] The electric wire 2 leads the current on the brush body 33 to the data acquisition instrument 1 through the first brush holder 35 and the threading hole 321 on the brush box 32 .

[0041] The two ends of the voltage sensor inside the data acquisition instrument 1 are respectively connected to the brush lead wire 2 and the reference ground 4. The potential difference between the two ends is the shaft voltage on the motor shaft. The data acquisition instrument 1 can realize real-time display and storage of test data through its own display / external computer.

[0042] During application, the brush part can be in direct contact with the output shaft of the motor transmission end, or it can be in direct contact with the coupling or dummy shaft according to the on-site environment.

[0043] Before the test begins, select a connector 5 of appropriate length according to the on-site environment of the motor under test, connect it to the brush box 32 to form a whole, select a suitable brush body 33 and an insulating brush holder 34 according to the diameter of the test motor shaft, and install them in the first brush holder 35, assemble the installed first brush holder 35 and the brush box 32, and lead the wire 2 out of the threading hole 321. After the brush box 32 is assembled, the wire 2 is connected to the voltage sensor of the data acquisition instrument 1, and the other end of the voltage sensor is connected to the reference ground 4 of the test platform to complete the installation of the shaft voltage test equipment.

[0044] After the installation is completed, the motor is started and tested according to the test conditions, and the shaft voltage data of the motor shaft to the ground is observed and recorded on the data acquisition instrument 1.

[0045] By using this solution, it is possible to perform shaft voltage testing without any modification to the existing motor. At the same time, this solution can realize shaft voltage testing in a small environment, and the brush body 33 can be replaced by itself and adapted to a variety of motor output shafts or couplings. It has the advantages of simple and safe operation and high accuracy of collected data.

[0046] In this embodiment, the test device is fixed on the motor so that the brush body 33 of the test device contacts the motor shaft to measure the motor shaft voltage. In addition to this method, a longer connector 5 can be used at the rear end of the brush box 32, and an insulating sheath is installed at the end of the connector 5. Then, during the test, the operator holds the insulating part of the connector 5 and presses the brush body 33 at the top of the brush box 32 against the motor shaft to lead out the electrical signal to measure the motor shaft voltage. Alternatively, the measuring device can be installed on a tooling near the motor, and the position between the tooling and the motor can be adjusted to make the brush body 33 contact the motor shaft.

[0047] In the second embodiment, the connector 5 is connected to a multi-channel component 6, the multi-channel component 6 is connected to a magnetic base 7, and the magnetic base 7 is adsorbed on the motor.

[0048] The magnetic base 7 can be adsorbed on the motor stator, and the magnetic base 7 and the connector 5 of the brush box 32 assembly are connected through the multi-pass assembly 6, so that the brush box 32 is fixed to the motor body, wherein the multi-pass assembly 6 can be tightened by a built-in knob to prevent the brush box 32 from being thrown out or falling during the test.

[0049] The external magnetic device is easy to install without damaging the paint surface of the original motor. It is suitable for shaft voltage testing during routine tests of the motor.

[0050] When in use, fix the magnetic base 7 on the motor stator housing, and use the multi-pass component 6 to connect and tighten the connector 5 of the brush box 32 to the magnetic base 7. After installation, rotate the motor to check whether the contact between the brush body 33 and the motor shaft is good, and ensure that the motor shaft rotates smoothly without jamming.

[0051] In the third embodiment, the connector 5 is connected to the mounting bracket 8, and the mounting bracket 8 is mounted on the process hole of the motor. The brush assembly 3 is mounted on the process hole of the motor or the magnetic base 7 through the rear connector 5, thereby avoiding damage to the original motor structure and not affecting the factory requirements of the motor.

[0052] In the fourth embodiment, the brush box 32 is provided with a safety buckle 322, and the first brush holder 35 is provided with a slide groove 352 cooperating with the safety buckle 322. The slide groove 352 is arranged along the extension and contraction direction of the spring, and the distance between the bottom of the slide groove 352 and the bottom of the first brush holder 35 is defined as a safety distance, which can avoid the problem of the brush assembly 3 falling off due to abnormal wear. The slide groove 352 can ensure that the brush part will not pop out of the brush box 32 due to excessive wear.

[0053] The brush box 32 of this embodiment can adopt a split structure divided into two parts, which is convenient for installing and fixing the first brush holder 35 and the spring. The spring is fixed by the internal buckle of the brush box 32, and continuously applies a constant force to the first brush holder 35, so that the brush body 33 can always maintain good contact with the motor shaft. It should be noted that the brush box 32 does not need to use a split structure. The installation method can adopt a method of providing a pin hole on the outer wall of the brush box 32. Specifically, after the first brush holder 35 is placed in the brush box 32, the safety buckle 322 is inserted into the pin hole, and then inserted into the slide groove 352 of the first brush holder 35, so that the first brush holder 35 and the brush box 32 can be assembled.

[0054] Working principle: The first brush holder 35 can be made of metal or non-metal material, and a slide groove 352 is arranged at the center thereof. The slide groove 352 cooperates with the safety buckle 322 in the brush box 32. The safety buckle 322 plays the function of sliding guidance and limiting, so as to prevent the brush body 33 from floating and swinging greatly and falling off due to abnormal wear.

[0055] The brush box 32 can be made of metal or non-metal material, and is provided with a safety buckle 322 inside, which cooperates with the slide groove 352 on the first brush holder 35. On the one hand, it is used to ensure that the first brush holder 35 can slide according to the specified trajectory. On the other hand, when the brush body 33 is worn a lot or abnormally worn, the protruding safety buckle 322 can lock the first brush holder 35 to prevent the first brush holder 35 from popping out and causing personal injury or other hazards.

[0056] In the fifth embodiment, one or more safety warning strips 353 are arranged on the outer wall of the first brush holder 35 to ensure that the brush body 33 will not have poor contact due to excessive wear.

[0057] The safety warning strip 353 can be designed according to the thickness of the brush body 33. When the brush body 33 is worn to expose the safety warning strip 353, it indicates that the brush body 33 needs to be replaced in time.

[0058] In the sixth embodiment, the data acquisition instrument 1 is provided with a plurality of voltage sensors, each of which is connected to a brush assembly 3 and a reference ground 4 through an electric wire 2. The device has a simple and adjustable structure and can be applied to shaft voltage testing in a narrow space, especially to solve the problem of difficulty in testing the transmission end of the motor due to the existence of a coupling. When a plurality of brush assemblies 3 are used simultaneously, the potential difference at both ends of the shaft can be measured, which is convenient for subsequent comparative analysis of shaft voltage data. By adding a brush box 32, the voltage between the shaft and the ground at both ends of the motor and the potential difference at both ends of the motor can be measured, which is convenient for subsequent comprehensive analysis of shaft voltage data and its influence on bearing electro-corrosion.

[0059] When in use, the shaft voltage measurement of the motor shaft to the ground can be carried out as required, or the brush assembly 3 can be installed at both ends of the motor in a combined form to measure the potential difference at both ends of the motor shaft and the shaft voltage at both ends of the motor to the ground.

[0060] The present invention has the following advantages: 1. The brush body 33 of the present invention can be made of different materials according to the requirements of the field test. In routine tests with high requirements for field conditions, conductive fibers can be selected to avoid the pollution of the motor bearing structure by carbon powder generated by traditional brushes.

[0061] 2. The brush body 33 of the present invention is designed to be replaceable, which is not only convenient for daily maintenance, but also allows the selection of brushes of different sizes according to the test motor to ensure good contact between the conductive brush and the motor shaft.

[0062] 3. The brush body 33 of the present invention can be designed with different shapes to match the corresponding motor products, which can not only increase the contact area between the conductive brush and the motor shaft and reduce the contact resistance, but also avoid the problems of high brush heating and breakage caused by traditional point and line contact.

[0063] 4. The brush body 33 of the present invention is controlled by a constant force spring 31, which can ensure that the brush body 33 is in good contact with the motor shaft at all times, avoiding the distortion of the measurement results caused by brush wear in the traditional structure. At the same time, with the arc-shaped brush body 33, more accurate shaft voltage data can be obtained.

[0064] 5. The first brush holder 35 of the present invention is equipped with a slide groove 352 and a safety warning strip 353, which can not only limit the relative movement of the brush body 33 and the motor shaft when they are in contact, causing the problem of test data fluctuation, but also the safety warning strip 353 can remind the on-site operator to replace the brush body 33 at the appropriate time to avoid data distortion caused by wear of the brush body 33.

[0065] 6. The brush box 32 of the present invention is equipped with a safety buckle 322. The safety buckle 322 cooperates with the slide groove 352 to not only avoid equipment damage and personal injury accidents caused by the contact between the insulating brush holder 34 and the rotating shaft after abnormal wear of the brush body 33, but also remind the on-site operator to replace the brush body 33 at an appropriate time.

[0066] 7. The brush box 32 and the connector 5 of the present invention are designed to be split, which is convenient to carry and can be adapted to connectors 5 of different lengths and types, thereby adapting to shaft voltage tests of motors of different types and volumes.

[0067] 8. The present invention has various installation methods. You can choose to use the magnetic base 7 to cooperate with the connector 5 to achieve quick installation without tools. You can also choose to connect the brush box 32 to the connecting rod and complete the installation by cooperating with the process holes on the motor end cover.

[0068] The above is only a specific implementation of the present invention, which enables those skilled in the art to understand or implement the present invention. Although detailed descriptions are given with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments, and they should all be covered by the protection scope of the claims.

Claims

1. A motor shaft voltage testing device, characterized in that: The invention comprises a data acquisition instrument (1) and a brush assembly (3); a voltage sensor inside the data acquisition instrument (1) is connected to the brush assembly (3) and a reference ground (4) via an electric wire (2), the brush assembly (3) comprises a brush box and a brush part; the brush part is insulated and connected to a spring, the spring is installed in the brush box (32), the brush part slides in the brush box (32) via the spring, the brush part is connected to the electric wire, and a threading hole (321) through which a power supply line (2) passes is provided at the bottom of the brush box (32).

2. A motor shaft voltage testing device according to claim 1, characterized in that: The spring is a constant force spring (31), the inner wall of the brush box (32) is provided with a buckle, and one end of the constant force spring (31) is connected to the buckle.

3. A motor shaft voltage testing device according to claim 1, characterized in that: The brush part comprises a brush body (33), the contact surface between the brush body (33) and the motor shaft is an arc surface, the brush body (33) is fixedly connected to an insulating brush holder (34), the insulating brush holder (34) is connected to a spring, and the brush body (33) is connected to an electric wire (2).

4. A motor shaft voltage testing device according to claim 1, characterized in that: It also includes a connecting piece (5), wherein the connecting piece (5) is connected to the outer wall of the brush box (32).

5. A motor shaft voltage testing device according to claim 3, characterized in that: The brush assembly (3) further comprises a first brush holder (35), the first brush holder (35) being arranged between the insulating brush holder (34) and the spring, the first brush holder (35) being arranged as a box body with a threading hole (321) at the bottom, the outer wall of the first brush holder (35) being arranged with a mounting hole (351), the insulating brush holder (34) extending into the interior of the first brush holder (35) and being fixedly connected to the first brush holder (35) by means of bolts passing through the mounting hole (351), the insulating brush holder (34) being arranged with a conductor (36) penetrating the insulating brush holder (34) from the top, the brush body (33) being connected to the conductor (36) at the top of the insulating brush holder (34), and the conductor (36) at the bottom of the insulating brush holder (34) being connected to the electric wire (2).

6. A motor shaft voltage testing device according to claim 4, characterized in that: The connecting member (5) is connected to a multi-channel component (6), the multi-channel component (6) is connected to a magnetic base (7), and the magnetic base (7) is adsorbed on the motor.

7. A motor shaft voltage testing device according to claim 4, characterized in that: The connecting piece (5) is connected to a mounting bracket (8), and the mounting bracket (8) is mounted on a process hole of the motor.

8. A motor shaft voltage testing device according to claim 5, characterized in that: The brush box (32) is provided with a safety buckle (322), and the first brush holder (35) is provided with a slide groove (352) that cooperates with the safety buckle (322). The slide groove (352) is arranged along the expansion and contraction direction of the spring, and the distance between the bottom of the slide groove (352) and the bottom of the first brush holder (35) is defined as a safety distance.

9. A motor shaft voltage testing device according to claim 8, characterized in that: One or more safety warning strips (353) are provided on the outer wall of the first brush holder (35).

10. A motor shaft voltage testing device according to any one of claims 1 to 9, characterized in that: The data acquisition instrument (1) is provided with a plurality of voltage sensors, each of which is connected to a brush assembly (3) and a reference ground (4) via an electric wire (2).

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