Three-phase asynchronous motor end cover insulation structure

Abstract

The invention belongs to the technical field of motor end covers, and particularly relates to a three-phase asynchronous motor end cover insulation structure which comprises a base, a front end cover, a weftless tape and bolts, a first insulation washer and a second insulation washer are arranged between the base and the front end cover, and the weftless tape is wound on the matching surface of the base and the front end cover. The first insulating washer and the second insulating washer are arranged between the motor base and the front end cover, and the weftless tape winding and the epoxy resin coating are matched, so that multiple insulating barriers are formed, a metal conductive path between the end cover and the motor base is effectively blocked, the possibility of shaft current generation is reduced, and the service life of the motor is prolonged. The first insulating washer and the second insulating washer adopt a composite structure with a sealing ring, good sealing is realized while the insulating property is ensured, dust and moisture are prevented from invading into the motor, the operation reliability of the motor is improved, the insulating tubes are sleeved among the bolt, the end cover and the base, the electrical isolation of the connecting part is ensured, and the bolt is prevented from becoming an electric leakage channel.

Description

Technical Field

[0001] This invention relates to the field of motor end cover technology, and more particularly to an insulation structure for a three-phase asynchronous motor end cover. Background Technology

[0002] During operation, a three-phase asynchronous motor generates an induced voltage at both ends of the rotor shaft under the influence of an alternating magnetic field. When this voltage exceeds the breakdown voltage of the bearing oil film, a shaft current will form, damaging the motor's insulation system. Traditionally, the motor end cover and frame are in direct metal-to-metal contact and rigidly connected by bolts, forming a metal-to-metal conductive path. Once leakage or short circuit occurs, it will seriously affect the motor's lifespan and operational safety.

[0003] In practical use, this structure has several shortcomings: First, the direct metal-to-metal contact between the end cap and the base provides a low-resistance path, which is not conducive to blocking shaft current. Second, the bolted connection lacks effective insulation and may become a leakage path. Third, the metal-to-metal contact between the bearing and the bearing housing of the end cap cannot prevent shaft voltage from being conducted through the bearing. Finally, the lack of an effective shaft voltage conduction mechanism leads to the accumulation of shaft current, which accelerates insulation aging and bearing damage. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides an insulation structure for the end cover of a three-phase asynchronous motor, which overcomes the deficiencies of existing technologies and effectively solves the problems of direct metal-to-metal contact forming a conductive path, inability to effectively block shaft current, susceptibility of bearings to electrolytic corrosion damage, and difficulty in achieving both insulation and sealing in traditional end cover structures.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: An insulating structure for an end cover of a three-phase asynchronous motor includes a frame, a front end cover, a non-woven tape, and bolts. A first insulating washer and a second insulating washer are provided between the frame and the front end cover. The mating surfaces of the frame and the front end cover are wrapped with non-woven tape. An insulating tube is fitted between the bolts, the front end cover, and the frame. An end cover bearing chamber is provided on the inner wall of the front end cover, and a bearing is provided on the inner wall of the end cover bearing chamber. A rotating shaft is provided on the inner ring of the bearing, and the rotating shaft passes through the interior of the frame and the front end cover.

[0006] Preferably, the second insulating washer is located inside the first insulating washer, and the second insulating washer and the first insulating washer are located inside and outside the front cover, respectively.

[0007] Preferably, the outer wall of the non-woven belt is coated with an epoxy resin layer.

[0008] Preferably, an insulating bushing is provided between the outer ring of the bearing and the bearing housing of the end cover.

[0009] Preferably, a conductive ring is installed at the extended end of the rotating shaft, and the conductive ring is in contact with the grounding brush, which is fixed to the grounding terminal of the base.

[0010] Preferably, the first insulating washer and the second insulating washer are a composite structure with a sealing ring, which has both insulation and sealing functions.

[0011] Preferably, the two ends of the insulating tube are in close contact with the base and the front cover, respectively.

[0012] Preferably, the non-woven tape is wound around the outer wall of the front end of the base.

[0013] The beneficial effects of this invention are as follows: The three-phase asynchronous motor end cover insulation structure of the present invention forms multiple insulation barriers by setting a first insulating washer and a second insulating washer between the frame and the front end cover, combined with non-woven tape winding and epoxy resin coating, which effectively blocks the metal conductive path between the end cover and the frame, reducing the possibility of shaft current generation. The first insulating washer and the second insulating washer adopt a composite structure with a sealing ring, which achieves good sealing while ensuring insulation performance, preventing dust and moisture from entering the motor and improving the reliability of motor operation. The three-phase asynchronous motor end cover insulation structure of this invention features an insulating tube fitted between the bolts and the end cover / frame to ensure electrical isolation at the connection points and prevent the bolts from becoming leakage current paths. An insulating bushing is installed between the bearing outer ring and the bearing housing of the end cover to further block the path of shaft voltage conduction through the bearing, protecting the bearing from electrolytic corrosion damage and extending its service life. The three-phase asynchronous motor end cover insulation structure of the present invention has a conductive ring installed on the extended end of the shaft and in contact with the grounding brush, which can promptly conduct the induced charge on the shaft to the ground and prevent the accumulation of shaft voltage. This design, which combines active conduction and passive isolation, significantly reduces the damage of shaft current to the motor insulation system, improves the safety and stability of motor operation, and is suitable for various three-phase asynchronous motors, especially for occasions with high requirements for insulation performance. Attached Figure Description

[0014] Figure 1 This is a three-dimensional structural schematic diagram of the end cover insulation structure of a three-phase asynchronous motor proposed in this invention. Figure 2 Based on Figure 1 A schematic diagram of the structure when half of the non-woven belt is removed; Figure 3 Based on Figure 2 A diagram showing the front cover being cut in half; Figure 4 This is a schematic diagram showing the overall structure of the insulation structure of the end cover of a three-phase asynchronous motor proposed in this invention.

[0015] In the diagram: 1. Base; 2. Front cover; 3. Non-woven belt; 4. First insulating washer; 5. Second insulating washer; 6. End cover bearing housing; 7. Bearing; 8. Insulating bushing; 9. Shaft; 10. Conductive ring; 11. Insulating tube; 12. Bolt. Detailed Implementation

[0016] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0017] Reference Figures 1-4 Example 1: An insulating structure for the end cover of a three-phase asynchronous motor includes a base 1, a front cover 2, a non-woven tape 3, and bolts 12. A first insulating washer 4 and a second insulating washer 5 are provided between the base 1 and the front cover 2. The non-woven tape 3 is wound around the mating surface of the base 1 and the front cover 2. The second insulating washer 5 is located inside the first insulating washer 4, and the second insulating washer 5 and the first insulating washer 4 are located inside and outside the front cover 2, respectively. The outer wall of the non-woven tape 3 is coated with an epoxy resin layer. The non-woven tape 3 is wound around the outer wall of the front end of the base 1. The first insulating washer 4 and the second insulating washer 5 are a composite structure with a sealing ring, which has both insulation and sealing functions.

[0018] The above-described scheme involves placing a first insulating washer 4 and a second insulating washer 5 between the base 1 and the front cover 2. The second insulating washer 5 is located inside the first insulating washer 4, positioned on the inner and outer sides of the front cover 2, respectively. A non-woven tape 3 is wound around the mating surfaces of the base 1 and the front cover 2, and an epoxy resin layer is coated on its outer wall to enhance insulation performance and mechanical strength. The first insulating washer 4 and the second insulating washer 5 employ a composite structure with a sealing ring, achieving a sealing function while isolating metal contact, effectively preventing external impurities from entering the motor.

[0019] In this embodiment, by setting a first insulating washer 4 and a second insulating washer 5 between the base 1 and the front end cover 2, combined with the non-woven tape 3 winding and epoxy resin coating, multiple insulating barriers are formed, effectively blocking the metal conductive path between the end cover and the base 1, and reducing the possibility of shaft current generation. The first insulating washer 4 and the second insulating washer 5 adopt a composite structure with a sealing ring, which achieves good sealing while ensuring insulation performance, preventing dust and moisture from entering the motor and improving the reliability of motor operation.

[0020] In embodiment 2, an insulating tube 11 is fitted between the bolt 12 and the front cover 2 and the base 1. The two ends of the insulating tube 11 are in close contact with the base 1 and the front cover 2, respectively. An end cover bearing chamber 6 is provided on the inner wall of the front cover 2, and a bearing 7 is provided on the inner wall of the end cover bearing chamber 6. A rotating shaft 9 is provided on the inner ring of the bearing 7, and the rotating shaft 9 passes through the interior of the base 1 and the front cover 2. An insulating bushing 8 is provided between the outer ring of the bearing 7 and the end cover bearing chamber 6. A conductive ring 10 is installed on the extended end of the rotating shaft 9. The conductive ring 10 is in contact with the grounding brush, and the grounding brush is fixed to the grounding terminal of the base 1.

[0021] Through the above scheme, an insulating tube 11 is fitted between bolt 12 and the front cover 2 and the base 1 to ensure electrical isolation at the bolt 12 connection point. The inner wall of the front cover 2 is provided with an end cover bearing chamber 6, in which a bearing 7 is installed. An insulating bushing 8 is provided between the outer ring of the bearing 7 and the end cover bearing chamber 6 to block the path of shaft voltage conduction through the bearing 7. The rotating shaft 9 passes through the base 1 and the front cover 2, and a conductive ring 10 is installed at its extended end. The conductive ring 10 contacts a grounding brush fixed to the grounding terminal of the base 1, realizing the effective release of induced charge on the rotating shaft 9. This invention constructs a comprehensive insulation protection system: the multiple insulation structure between the base 1 and the end cover blocks the radial conductive path; the bolt 12 and the insulating tube 11 prevent axial leakage; the bearing 7 and the insulating bushing 8 protect the critical rotating parts; and the conductive ring 10 and the grounding brush system actively guide the shaft voltage, fundamentally reducing the risk of shaft current generation.

[0022] In this embodiment, an insulating tube 11 is fitted between the bolt 12 and the end cover and the base 1 to ensure electrical isolation at the connection point and prevent the bolt 12 from becoming a leakage current path. An insulating bushing 8 is provided between the outer ring of the bearing 7 and the bearing housing 6 of the end cover to further block the path of shaft voltage conduction through the bearing 7, protect the bearing 7 from electrolytic corrosion damage, and extend its service life. A conductive ring 10 is installed on the extended end of the shaft 9 and contacts the grounding brush, which can promptly conduct the induced charge on the shaft 9 to the ground and prevent the accumulation of shaft voltage. This design, which combines active conduction with passive isolation, significantly reduces the damage of shaft current to the motor insulation system, improves the safety and stability of motor operation, and is suitable for various three-phase asynchronous motors, especially for applications with high insulation performance requirements.

[0023] Working Principle: When a three-phase asynchronous motor is running, the induced voltage generated by the rotor in the alternating magnetic field will cause a potential difference across the two ends of the shaft 9. If no measures are taken, this voltage may break down the oil film of the bearing 7, forming a shaft current and damaging the insulation system. This invention blocks possible conductive paths through multiple insulation structures: the first insulating washer 4 and the second insulating washer 5 isolate the metal contact between the base 1 and the end cover; the non-woven tape 3 and the epoxy resin coating further enhance the insulation effect; the insulating tube 11 ensures that no leakage current path is formed at the bolt 12 connection; and the insulating bushing 8 prevents electrical conduction between the outer ring of the bearing 7 and the bearing chamber 6 of the end cover.

[0024] Meanwhile, the conductive ring 10 at the extended end of the shaft 9 contacts the grounding brush, promptly conducting the induced charge on the shaft 9 to the ground and preventing shaft voltage accumulation. This dual mechanism of "isolation + conduction" effectively reduces the possibility of shaft current generation, protects the motor insulation system and bearing 7, and improves the safety and reliability of motor operation.

[0025] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A three-phase asynchronous motor end cover insulation structure, comprising a base (1), a front end cover (2), a weftless tape (3), a bolt (12), characterized in that, The first insulating washer (4) and the second insulating washer (5) are arranged between the base (1) and the front end cover (2), the no-weft tape (3) is wound on the mating surface of the base (1) and the front end cover (2), the bolt (12) is sleeved with the insulating tube (11) between the front end cover (2) and the base (1), the inner wall of the front end cover (2) is provided with the end cover bearing chamber (6), the inner wall of the end cover bearing chamber (6) is provided with the bearing (7), the inner ring of the bearing (7) is provided with the rotating shaft (9), and the rotating shaft (9) penetrates through the inside of the base (1) and the front end cover (2).

2. A three-phase asynchronous motor end cover insulation structure according to claim 1, characterized in that, The second insulating washer (5) is located on the inner side of the first insulating washer (4), and the second insulating washer (5) and the first insulating washer (4) are located on the inner side and the outer side of the front end cover (2) respectively.

3. A three-phase asynchronous motor end cover insulation structure according to claim 1, characterized in that, The outer wall of the no-weft tape (3) is coated with an epoxy resin layer.

4. A three-phase asynchronous motor end shield insulation structure according to claim 1, characterized in that, The outer ring of the bearing (7) is provided with the insulating bushing (8) between the end cover bearing chamber (6).

5. A three-phase asynchronous motor end shield insulation structure according to claim 1, characterized in that, The outer end of the rotating shaft (9) is provided with the conductive ring (10), the conductive ring (10) is in contact with the grounding brush, and the grounding brush is fixed on the grounding terminal of the base (1).

6. A three-phase asynchronous motor end shield insulation structure according to claim 1, characterized in that, The first insulating washer (4) and the second insulating washer (5) are composite structures with sealing rings, and have the functions of insulation and sealing.

7. A three-phase asynchronous motor end shield insulation structure according to claim 1, characterized in that, The insulating tube (11) is in close contact with the base (1) and the front end cover (2) at both ends.

8. A three-phase asynchronous motor end shield insulation structure according to claim 1, characterized in that, The no-weft tape (3) is wound on the outer wall of the front end of the base (1).

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