Paint film structure of high-performance enameled electromagnetic wire for motor

Abstract

The paint film structure of the high-performance enameled electromagnetic wire for the motor comprises a bottom layer, a middle layer and an outer layer which are sequentially coated on a conductor from inside to outside, the bottom layer is a first paint layer, and the first paint layer is composed of high-adherence polyimide paint; the middle layer is composed of one or two of a second paint layer and a third paint layer, the third paint layer is located on the outer side of the second paint layer, the second paint layer is composed of polyimide paint with the relative dielectric constant being 1.5-2.8, and the third paint layer is composed of corona-resistant polyimide paint; the outer layer is a fourth paint layer, and the fourth paint layer is composed of wear-resistant polyimide paint or oil-resistant polyimide paint. The paint film structure is good in temperature resistance, corona resistance and PDIV performance requirements, the proportion of the two layers of paint films in the middle can be adjusted according to the requirements, the paint film structure has good wear resistance, the mechanical performance requirements of production line forming can be met, and the paint film processing cost can be controlled to be at a low level. And meanwhile, the compatibility of various different ATF oils can be met.

Description

Technical Field

[0001] The utility model relates to the field of electricity, in particular to an electromagnetic wire of a motor winding, and more particularly to a paint film structure of a high-performance enameled electromagnetic wire for a motor. Background Art

[0002] Enameled magnet wire is widely used in various motor winding designs, particularly in the field of new energy drive motors, where its application has become mainstream. Furthermore, since new energy drive motors utilize variable frequency drives (VFDs), high voltage spikes are generated during operation. Furthermore, automotive drive motors operate at relatively high speeds, and to achieve high efficiency, the switching frequency of the VFD must also be relatively high, placing very high demands on the performance of the enameled wire.

[0003] The transition from 400V to 800V has seen significant changes in both the type and structure of paint films. This shift has primarily been made from the original PEI and PAI enameled wires to the more heat-resistant PI enameled wires. This has also led to higher requirements for the enameled wire's PDIV onset partial discharge voltage and corona resistance (bipolar square wave), as well as increased heat resistance. Beyond these high-performance requirements, the enameled wire also requires excellent mechanical properties during the molding process, minimal damage during molding, and minimal loss of electrical performance. Furthermore, the cost of processing the enameled wire must be considered.

[0004] In particular, the design and application of flat-wire coating structures are becoming increasingly clear, flexible, and diverse. To meet the diverse performance requirements of different projects, targeted coating structure design and manufacturing can be performed while balancing performance and cost, optimizing coating structures and reducing redundancy. Furthermore, through gradual application, relatively comprehensive performance indicator testing methods and standards have been established.

[0005] In the prior art, electromagnetic enameled wire still has the following defects:

[0006] 1. In the welding of short PIN, due to the short bare copper part, the existing paint film is easily affected by the welding heat and warped, affecting the performance of the paint film;

[0007] 2. Existing copper wire paint films have three or two layers, with the outermost layer being a corona-resistant layer or a corona-resistant, high-temperature, and high-humidity-resistant layer. During the magnet wire forming process, the outermost layer, being corona-resistant, generates significant friction with the tooling. Furthermore, the corona-resistant layer contains inorganic particles, which can cause significant frictional damage. This can damage the paint film at best, or even cause it to break off into small pieces. Summary of the Invention

[0008] The purpose of the utility model is to provide a paint film structure for a high-performance enameled electromagnetic wire for a motor, which aims to solve the technical problems in the prior art that the paint film is easily affected by welding heat and warps, and the outermost corona-resistant paint layer is seriously damaged during processing.

[0009] The utility model discloses a paint film structure of a high-performance enameled electromagnetic wire for a motor, comprising a bottom layer, a middle layer and an outer layer sequentially coated on a conductor from the inside to the outside;

[0010] The bottom layer is a first paint layer, and the first paint layer is composed of a high-adhesion polyimide paint;

[0011] The intermediate layer is composed of one or both of a second paint layer and a third paint layer, the third paint layer is located outside the second paint layer, the second paint layer is composed of a polyimide paint with a relative dielectric constant of 1.5 to 2.8, and the third paint layer is composed of a corona-resistant polyimide paint;

[0012] The outer layer is the fourth paint layer, and the fourth paint layer is composed of wear-resistant polyimide paint or oil-resistant polyimide paint.

[0013] Furthermore, the third paint layer is composed of corona-resistant, high-temperature-resistant and high-humidity polyimide paint.

[0014] Furthermore, the corona-resistant polyimide paint contains inorganic nanofillers.

[0015] Furthermore, the inorganic nanofiller is SiO2.

[0016] Furthermore, the inorganic nanofiller accounts for 1%-40%.

[0017] Furthermore, the fourth paint layer is composed of wear-resistant, high-temperature and high-humidity resistant polyimide paint.

[0018] Furthermore, the wear-resistant, high-temperature and high-humidity resistant polyimide paint contains a polyimide precursor solution.

[0019] Furthermore, the polyimide paint is selected from one of aliphatic polyimide paint, semi-aromatic polyimide paint or aromatic polyimide paint.

[0020] Furthermore, the thickness of the first paint layer is 5um to 15um.

[0021] Furthermore, the thickness of the fourth paint layer is 5um to 20um.

[0022] Furthermore, the total thickness of a single side of the paint film structure is 50um to 200um.

[0023] Compared with existing technologies, this utility model has significant and positive effects. The paint film structure has excellent temperature resistance, and the ratio of the two intermediate layers can be adjusted to meet the requirements for corona and PDIV resistance. It also offers excellent wear resistance and meets the mechanical performance requirements of production line molding, while also keeping paint film processing costs low. Furthermore, it is compatible with various ATF oils. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagrams of embodiments 1 and 2 of the paint film structure of a high-performance enameled electromagnetic wire for a motor according to the present invention.

[0025] Figure 2 This is a schematic diagram of Example 3 of a paint film structure of a high-performance enameled electromagnetic wire for a motor according to the present invention.

[0026] Figure 3 This is a schematic diagram of Example 4 of a paint film structure of a high-performance enameled electromagnetic wire for a motor according to the present invention.

[0027] Figure 4 This is a schematic diagram of the structural formulas of two polyimide precursors in the paint film structure of a high-performance enameled electromagnetic wire for motors according to the present invention. DETAILED DESCRIPTION

[0028] The following is a further description of the present invention in conjunction with an embodiment. However, the present invention is not limited to the embodiment. All similar structures and similar variations of the present invention should be included in the scope of protection of the present invention. The use of directions such as up, down, front, back, left, and right in the present invention is only for the convenience of clear description and does not limit the technical solution of the present invention.

[0029] like Figures 1-4 As shown, the paint film structure of a high-performance enameled electromagnetic wire for a motor of the present invention includes a bottom layer, a middle layer and an outer layer sequentially coated on a conductor 5 from the inside to the outside;

[0030] The bottom layer is the first paint layer 1, which is composed of a high-adhesion polyimide paint and has good adhesion to the copper material. After curing, the copper wire will not be delaminated during the forming process.

[0031] The intermediate layer is composed of one or both of a second paint layer 2 and a third paint layer 3, wherein the third paint layer 3 is located outside the second paint layer 2, the second paint layer 2 is composed of a polyimide paint having a relative dielectric constant of 1.5 to 2.8, and the third paint layer 3 is composed of a corona-resistant polyimide paint;

[0032] The outer layer is the fourth paint layer 4, and the fourth paint layer 4 is composed of wear-resistant polyimide paint or oil-resistant polyimide paint.

[0033] Specifically, the low dielectric constant of a polyimide varnish with a dielectric constant of 1.8 to 2.5 is determined by the proportion of air bubbles in the cured varnish. The more bubbles, the lower the relative dielectric constant. To balance the mechanical properties of the copper wire, the selected polyimide varnish has a relative dielectric constant of no less than 1.8. The bubbles are formed by the thermal decomposition of the low-decomposition-temperature ester in the low-dielectric varnish. The average pore size of the bubbles in the cured low-dielectric varnish is less than 10 μm, typically less than 3 μm, and less than 1 μm for optimal performance.

[0034] Furthermore, the third paint layer 3 is composed of corona-resistant, high-temperature-resistant and high-humidity polyimide paint.

[0035] Furthermore, the corona-resistant polyimide paint contains inorganic nanofillers.

[0036] Furthermore, the inorganic nanofiller is SiO2.

[0037] Furthermore, the inorganic nanofiller accounts for 1%-40%.

[0038] Furthermore, the fourth paint layer 4 is composed of wear-resistant, high-temperature and high-humidity resistant polyimide paint.

[0039] Furthermore, the wear-resistant, high-temperature and high-humidity resistant polyimide paint contains a polyimide precursor solution.

[0040] Furthermore, the polyimide paint is selected from one of aliphatic polyimide paint, semi-aromatic polyimide paint or aromatic polyimide paint.

[0041] Furthermore, the thickness of the first paint layer 1 is 5um to 15um.

[0042] Furthermore, the thickness of the fourth paint layer 4 is 5 μm to 20 μm, which can meet the requirements for electromagnetic wire forming.

[0043] Furthermore, the total thickness of a single side of the paint film structure is 50um to 200um.

[0044] Specifically, the high-adhesion polyimide paint, corona-resistant polyimide paint, wear-resistant polyimide paint, oil-resistant polyimide paint, corona-resistant, high-temperature and high-humidity polyimide paint, wear-resistant, high-temperature and high-humidity polyimide paint, self-aliphatic polyimide paint, semi-aromatic polyimide paint or aromatic polyimide paint in this embodiment all adopt well-known solutions in the prior art, which are understood by those skilled in the art and will not be repeated here.

[0045] Advantages of this utility model:

[0046] 1. Good temperature resistance

[0047] The first paint layer 1, the second paint layer 2, the third paint layer 3 and the fourth paint layer 4 are all composed of polyimide paint. The overall temperature resistance level of the finished enameled wire can reach above 240°C. It has good heat resistance and can meet the welding requirements of a shorter straight section of bare copper with a size of 3mm during welding. The welding heat does not damage the paint film and will not cause blistering or discoloration due to the welding heat.

[0048] 2. High PDIV

[0049] Use low dielectric polyimide paint as the second paint layer 2. For projects with higher PDIV requirements, use low dielectric paint for multiple coats to increase the PDIV initiation partial discharge voltage of the entire electromagnetic wire.

[0050] 3. Good corona resistance

[0051] The third paint layer 3 is coated with a corona-resistant polyimide paint.

[0052] 4. Good mechanical properties

[0053] The fourth paint layer 4 is made of wear-resistant or oil-resistant polyimide paint, which can avoid the problem of slag falling during the molding process when the corona-resistant polyimide paint is used as the outer layer. During the molding process, the paint film is less damaged and the loss of insulation performance is less.

[0054] 5. ATF oil resistance

[0055] For oil-cooled motors, since the fourth paint layer 4 adopts oil-resistant polyimide paint and the third paint layer 3 adopts corona-resistant, high-temperature and high-humidity polyimide paint, the overall ATF oil resistance of the electromagnetic wire is outstanding, and can fully meet the oil resistance requirements of the 415 group standard of high and low temperature impact -45℃, 8h-155℃, 40h8 cycle.

[0056] 6. Large space for structural adjustment and reasonable cost

[0057] The proportions of the first paint layer 1, the second paint layer 2, the third paint layer 3, and the fourth paint layer 4 of this structure can be adjusted. The proportions of the second paint layer (20% to 90%) and the third paint layer (30% to 90%) can be adjusted arbitrarily to meet different performance requirements, reduce the cost of the paint film structure, and achieve the optimal cost.

[0058] In summary, this paint film structure offers excellent heat resistance. The ratio of the two middle layers can be adjusted to meet the requirements for corona and PDIV resistance. It also exhibits excellent wear resistance and meets the mechanical performance requirements of production line molding, while keeping paint film processing costs low. Furthermore, it is compatible with various ATF oils.

[0059] Example 1

[0060] In view of the demand for water-cooled motors, the following structure can be designed: Figure 1 As shown, the first paint layer 1 is a high-adhesion polyimide paint with a thickness of 5 to 15 μm; the second paint layer 2 is a low-dielectric polyimide paint with a relative dielectric constant of 1.8 and a thickness of 40 to 60 μm; the third paint layer 3 is a corona-resistant polyimide paint with a thickness of 40 to 60 μm, which can avoid damage during the paint film processing process. The corona-resistant polyimide paint is composed of inorganic nanofillers uniformly dispersed in the polyimide paint. The inorganic nanofillers are usually composed of one or more of SiO2, SiC, TiO2, Al2O3, and Cr2O3, and the particle size is usually 10 to 1000 nm. The proportion of the inorganic nanofillers ranges from 1% to 40%. The inorganic nanofiller in this embodiment is SiO2, and the filler mass ratio after curing is about 16%; the fourth paint layer 4 is a wear-resistant polyimide paint. Compared with the third paint layer 3, it does not contain inorganic nanofillers and has a thickness of 5 to 20 μm. Compared with the corona-resistant polyimide paint, it has better wear resistance. During the copper wire forming process, it is not easy for the surface paint film to be scraped off, peeling, or falling off, effectively ensuring product quality.

[0061] When the single-side paint film thickness is 50um-200um, PDIV ≥ 1800Vp can be achieved. The corona resistance time is ≥ 1000h under the conditions of impulse steady-state voltage ± 1500V, switching frequency 20kHz, and rise time 100ns.

[0062] Example 2

[0063] In response to the needs of oil-cooled motors, the following structure can be designed: Figure 1 As shown, the first paint layer 1 is a high-adhesion polyimide paint with a thickness of 5 to 10um. The second paint layer 2 is a low-dielectric polyimide paint with a relative dielectric constant of 1.8 and a thickness of 40 to 60um. The third paint layer 3 is a corona-resistant, high-temperature, and high-humidity resistant polyimide paint. The corona resistance is composed of inorganic nanofillers uniformly dispersed in the polyimide paint. The inorganic nanofillers are usually composed of one or more of SiO2, SiC, TiO2, Al2O3, and Cr2O3. The particle size is usually 10 to 1000nm. The proportion of the inorganic nanofiller ranges from 1% to 40%. The high-temperature and high-humidity resistance is achieved by two different structures of polyimide precursors described below according to a specific ratio, which can greatly improve the hydrolysis resistance of the cured polyimide paint. The high-temperature and high-humidity resistant polyimide varnish contains Figure 4 A polyimide precursor solution of structural unit (I) shown in formula (I) 6 and structural unit (II) shown in formula (II) 7, wherein the molar ratio of structural unit (II) to structural unit (I) is 60 / 40 to 90 / 10.

[0064] The nanofiller in this embodiment is SiO2, with a filler mass ratio of approximately 16% after curing and a thickness of 40-60 μm. The fourth paint layer 4 is a wear-resistant, high-temperature, and high-humidity resistant polyimide paint with a thickness of 5-20 μm. Similar to the third paint layer 3, this polyimide paint is composed of two polyimide precursors with different structures in a specific ratio. Compared to the third paint layer 3, the fourth paint layer 4 does not contain inorganic nanofillers, significantly improving the hydrolysis resistance of the cured polyimide paint. Furthermore, oil-cooled motor copper wire manufactured with this structure, according to the closed oil resistance test method specified in the T / CEEIA 415-2009 standard, maintains over 90% of its performance after a high-low temperature shock cycle from -45°C (8 hours) to 155°C (40 hours) in ATF containing 5000 ppm deionized water.

[0065] When the single-sided paint film thickness is 120μm, it can achieve a PDIV ≥ 1800Vp and a corona resistance time of ≥ 1000h under the conditions of an impact steady-state voltage of ±1500V, a switching frequency of 20kHz, and a rise time of 100ns. Furthermore, it can maintain over 90% of its performance after 8 cycles of high and low temperature shock from -45°C (8h) to 155°C (40h).

[0066] All of the above polyimide varnishes are selected from at least one of aliphatic polyimide varnish, semi-aromatic polyimide varnish or aromatic polyimide varnish. At the same time, oil-resistant wire enamels are prepared by polymerizing different monomers in different proportions.

[0067] Example 3

[0068] In order to meet the different requirements of different customers for copper wire performance, the ratio of the second paint layer 2 and the third paint layer 3 can be adjusted arbitrarily. In extreme cases, it can be as follows Figure 2 and Figure 3 Three-layer paint film structure. Figure 2 and Figure 3 The demand between performance requirements can be adopted Figure 1 The structure is achieved by adjusting the proportion of paint layers.

[0069] For customers who require high PDIV performance, such as a 120um paint film on one side, requiring PDIV ≥ 2100Vp, but no requirements for corona resistance, it can be as follows Figure 2 In the structure shown, the middle layer is composed of the second varnish layer 2, which is a polyimide varnish having a relative dielectric constant of 1.8 to 2.5.

[0070] Example 4

[0071] According to customer needs, the PDIV requirement is relatively low, for example, for a 120um paint film on one side, the PDIV is required to be ≥1500Vp, while the corona resistance requirement is very high, such as under the conditions of impulse steady-state voltage ±1500V, switching frequency 20kHz, and rise time 100ns, the corona resistance time is ≥1000h, which can be as follows Figure 3 In the structure shown, the middle layer is composed of the third paint layer 3, namely, the corona-resistant polyimide paint.

Claims

1. A paint film structure for a high-performance enameled magnet wire for a motor, comprising a bottom layer, an intermediate layer, and an outer layer sequentially coated on a conductor from the inside out; characterized in that: The bottom layer is a first paint layer, and the first paint layer is composed of a high-adhesion polyimide paint; The intermediate layer is composed of one or both of a second paint layer and a third paint layer, the third paint layer is located outside the second paint layer, the second paint layer is composed of a polyimide paint with a relative dielectric constant of 1.5 to 2.8, and the third paint layer is composed of a corona-resistant polyimide paint; The outer layer is the fourth paint layer, and the fourth paint layer is composed of wear-resistant polyimide paint or oil-resistant polyimide paint.

2. The paint film structure of the high-performance enameled magnet wire for motors according to claim 1, characterized in that: The third paint layer is composed of corona-resistant, high-temperature-resistant and high-humidity polyimide paint.

3. The paint film structure of a high-performance enameled magnet wire for a motor according to claim 1 or 2, characterized in that: The corona-resistant polyimide paint contains inorganic nanofillers.

4. The paint film structure of the high-performance enameled magnet wire for motors according to claim 3, characterized in that: The inorganic nanofiller is SiO2.

5. The paint film structure of the high-performance enameled magnet wire for motors according to claim 3, characterized in that: The inorganic nanofiller accounts for 1%-40%.

6. The paint film structure of the high-performance enameled magnet wire for motors according to claim 1, characterized in that: The fourth paint layer is composed of wear-resistant, high-temperature and high-humidity resistant polyimide paint.

7. The paint film structure of the high-performance enameled electromagnetic wire for motors according to claim 6, characterized in that: The wear-resistant, high-temperature and high-humidity resistant polyimide paint contains a polyimide precursor solution.

8. The paint film structure of the high-performance enameled magnet wire for motors according to claim 7, characterized in that: The polyimide paint is selected from one of aliphatic polyimide paint, semi-aromatic polyimide paint or aromatic polyimide paint.

9. The paint film structure of the high-performance enameled magnet wire for motors according to claim 1, characterized in that: The thickness of the first paint layer is 5um-15um.

10. The paint film structure of the high-performance enameled magnet wire for motors according to claim 1, characterized in that: The thickness of the fourth paint layer is 5um~20um.

11. The paint film structure of the high-performance enameled magnet wire for motors according to claim 1, characterized in that: The total thickness of one side of the paint film structure is 50um~200um.

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