Inner and outer double-coil induction heating structure of special-shaped motor stator hot jacket and gradient heating method

Abstract

The invention relates to the technical field of motor stator hot jackets, and discloses an inner and outer double-coil induction heating structure for a special-shaped motor stator hot jacket and a gradient heating method, and two sets of intermediate frequency power supplies are adopted to independently control an inner coil and an outer coil respectively. According to the invention, the uniformity of the temperature and the swelling amount of the special-shaped motor shell with a complex structure in the induction heating process can be ensured, so that the yield of the stator hot jacket is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of motor assembly, in particular to an induction heating technology for a special-shaped motor stator, specifically to an inner and outer double-coil induction heating structure of a special-shaped motor stator heat sleeve and a gradient heating method. Background Art

[0002] For the assembly of motor stators, the traditional press-fit technology has problems such as low efficiency and easy scratching of the workpiece surface. The shrink-fit technology makes the shell expand by heating, making the stator easier to assemble, and has been widely used in the assembly process of motor stators. However, the heating methods of traditional shrink-fit technology include furnace heating and infrared halogen lamp heating, which have the disadvantages of being time-consuming and low energy efficiency.

[0003] Induction heating technology uses the principle of electromagnetic induction. An induction coil with alternating current is placed close to the workpiece to generate eddy currents on the workpiece surface. It has the characteristics of high efficiency, fast speed, and easy automation, and has become a common heating method for shrink fit assembly. However, for special-shaped motor housings, usually only the stator assembly holes are heated, resulting in uneven housing temperature distribution, local deformation, and affecting the shape of the assembly holes, which in turn leads to stator assembly failure. Therefore, a set of special heating coil structures is required to ensure temperature uniformity during the heating process of special-shaped motor housings. Summary of the invention

[0004] The purpose of the present invention is to design an inner and outer double-coil induction heating structure for heat-shrinking the stator of a special-shaped motor, and at the same time provide a gradient heating method to improve the efficiency and success rate of heat-shrinking the stator of a special-shaped motor, in order to solve the problem that only the stator assembly holes of the special-shaped motor housing are heated, resulting in uneven temperature distribution of the housing, local deformation, and affecting the shape of the assembly holes, which in turn leads to stator assembly failure.

[0005] One of the technical solutions of the present invention is:

[0006] An inner and outer double-coil induction heating structure for heat-shrink sleeve of a special-shaped motor stator is characterized in that it consists of an inner coil 2 and an outer coil 3, the inner coil 2 is a solenoid structure, extends into the stator assembly hole, and heats the assembly hole, the outer coil 3 is a contoured structure, sleeved on the outer surface of the shell, and supplements the heat to the outer surface, and two sets of medium-frequency power supplies are used to independently control the heating of the inner coil 2 and the outer coil 3.

[0007] The inner coil 2 of the solenoid structure has its axial diameter and number of winding turns determined according to the aperture and depth of the assembly hole, and the entire assembly hole surface should be covered by the coil, with the matching surface of the stator assembly hole as the main heating surface 5. During the winding process, the gap between the inner coil 2 and the main heating surface 5 should be controlled to be 1-3mm.

[0008] Based on the distance from the main heating surface 5, the outer surface of the shell is divided into a distal surface 7 and a proximal surface 6. The outer coil 3 of the contoured structure should cover the distal surface 7. For the proximal surface 6 and the thin-walled area of ​​the shell, the outer coil 3 is not set or the distance between the outer coil 3 and the outer surface of the area is enlarged; the cross-section of the area surrounded by the outer coil is larger than the maximum cross-section of the shell to avoid interference with the shell, and the minimum gap between the outer coil 3 and the distal surface 7 is 1-3mm.

[0009] The inner coil 2 and the outer coil 3 are both copper tube coils that can pass cooling water, and have cooling water interfaces 4 at both ends. To avoid interference, the axial pitch of the inner coil 2 and the outer coil 3 is 1.2-1.5 times the outer diameter of the copper tube section.

[0010] In order to prevent the conflict of magnetic field directions generated by the inner and outer coils in the heating area, the inner coil 2 and the outer coil 3 have opposite rotation directions or the phase difference of the alternating current is controlled to be π.

[0011] The second technical solution of the present invention is:

[0012] A gradient heating method based on the inner and outer double coil induction heating structure of the special-shaped motor stator heat sleeve, characterized in that: during the heating process, a gradient heating method is adopted, and when the maximum temperature of the shell reaches one-third and two-thirds of the target temperature, the power of the inner coil (2) and the outer coil (3) is adjusted to keep the shell warm for 60-100 seconds. After the insulation is completed, heating is continued at the initial power value. When the maximum temperature of the shell reaches the highest value, the output power is adjusted to one-third of the initial value until the temperature difference between the highest temperature and the lowest temperature on the shell is within 10°C.

[0013] The beneficial effects of the present invention are:

[0014] The present invention provides an inner and outer double coil induction heating structure and a gradient heating method for heat-shrinking of special-shaped motor stators. The inner and outer double coils are heated to keep the temperature uniformity of the motor housing during the heating process, reduce the temperature difference caused by the temperature gradient formed during the heat conduction process, and then ensure the uniformity of the aperture expansion of the housing during the thermal expansion process, thereby improving the efficiency and success rate of heat-shrinking of the motor stator. Since the inner and outer coils use two sets of independent control power supplies, the controllability of the heating structure is increased, the temperature control is more accurate, and the temperature difference of each part of the housing can be accurately controlled within ±5°C, ensuring that the deformation of each part is within an acceptable range. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the induction heating structure in an embodiment of the present invention.

[0016] Figure 2 1 is a top view of the heating structure in an embodiment of the present invention.

[0017] Figure 3 Schematic diagram of inner and outer coils in an embodiment of the present invention.

[0018] Figure 4 Schematic diagram of key features of the motor housing in an embodiment of the present invention.

[0019] Figure 5 It is a temperature distribution cloud diagram after the shell is heated in the embodiment of the present invention.

[0020] In the figure: 1 is the motor housing, 2 is the inner coil, 3 is the outer coil; 4 is the cooling water interface; 5 is the main heating surface, 6 is the proximal surface, and 7 is the distal surface. DETAILED DESCRIPTION

[0021] In order to make the technical means, creative features, objectives and effects of the present invention easier to understand, the present invention is further described in conjunction with the accompanying drawings and embodiments.

[0022] like Figure 1 shown.

[0023] The motor stator heat-shrink sleeve induction heating structure described in the embodiment of the present invention is used to heat a motor housing 1 of a certain type, and the heating structure includes an inner coil 2 and an outer coil 3. Figure 3 As shown, the inner coil 2 and the outer coil 3 are both copper tube coils, with an inner diameter of 6 mm and an outer diameter of 8 mm, and cooling water interfaces 4 are connected at both ends. During the heating process, an industrial water cooler is used to continuously supply cooling water to prevent the conductivity of the coil body material from changing due to overheating, and to cool the power components and transformer inside the heating equipment. Figure 4 As shown, in the structural analysis of the shell, the main heating surface 5, the proximal surface 6 and the distal surface 7 are determined. According to the results of the structural analysis, the inner coil axis is determined to have a diameter of 40mm, a pitch of 12mm, 11 turns, and a right-handed rotation. The outer coil is divided into three parts: the top coil, the middle coil and the bottom coil. The top coil axis is a rectangular solenoid with a length of 207mm and a width of 127mm; the number of turns is 5, the middle coil axis is a rectangular solenoid with a length of 217mm and a width of 137mm, and the number of turns is 4; the bottom coil axis is a rectangular solenoid with a length of 162mm and a width of 82mm, and the number of turns is 3. The rotation directions of the three parts are all left-handed, and the pitch is 12mm. The inner and outer coils are controlled by two sets of medium-frequency induction power supplies respectively, and do not interfere with each other. The frequency of the alternating current passed through the inner and outer coils is 20KHz. The initial current of the inner coil is 600A, and the initial current of the outer coil is 450A. When the maximum temperature of the shell reaches 67℃ and 134℃ respectively, the heating power is adjusted to 30% of the initial value, and the heat preservation is continued for 60-100 seconds. After the heat preservation is completed, the heating is continued at the initial power. When the maximum temperature of the shell reaches 200℃, the output power is adjusted to 37% of the initial value. The final temperature distribution of the shell is as follows Figure 5 As shown, the highest temperature is 204.1°C, the lowest temperature is 195.5°C, and the overall temperature difference is 8.6°C. The average radial expansion of the assembly hole is 0.11mm.

[0024] Comparative Example:

[0025] The parameters of the heating coil are the same as those of Example 1, except that the heating process is not divided into stages, but directly heated to 200°C, and no insulation measures are added during the entire process. The final overall temperature difference exceeds 20°C, and the power consumption and time consumption are both increased by more than 30% compared with Example 1.

[0026] The present invention does not involve parts that are the same as the prior art or can be implemented by using the prior art.

Claims

1. An inner and outer double coil induction heating structure of a special-shaped motor stator heat sleeve, characterized by: It consists of an inner coil (2) and an outer coil (3). The inner coil (2) is a solenoid structure and extends into a stator assembly hole to heat the assembly hole. The outer coil (3) is a contoured structure and is sleeved on the outer surface of a shell to provide supplementary heat to the outer surface. Two sets of medium frequency power supplies are used to independently control the heating of the inner coil (2) and the outer coil (3).

2. The inner and outer double coil induction heating structure of the special-shaped motor stator shrink sleeve according to claim 1 is characterized in that: The inner coil (2) of the solenoid structure has its axis diameter and number of winding turns determined according to the diameter and depth of the assembly hole, and the entire surface of the assembly hole should be covered by the coil, with the mating surface of the stator assembly hole as the main heating surface (5). During the winding process, the gap between the inner coil (2) and the main heating surface (5) should be controlled to be 1-3 mm.

3. The inner and outer double coil induction heating structure of the special-shaped motor stator shrink sleeve according to claim 1 is characterized in that: The outer surface of the shell is divided into a proximal surface (6) and a distal surface (7) based on the distance from the main heating surface (5). The outer coil (3) of the contoured structure should cover the distal surface (7). For the proximal surface (6) and the thin-walled area of ​​the shell, the outer coil (3) is not set or the distance between the outer coil (3) and the outer surface of the area is enlarged; the cross-section of the area surrounded by the outer coil is larger than the maximum cross-section of the shell to avoid interference with the shell, and the minimum gap between the outer coil (3) and the distal surface (7) is 1-3 mm.

4. The inner and outer double coil induction heating structure of the special-shaped motor stator shrink sleeve according to claim 1 is characterized in that: The inner coil (2) and the outer coil (3) are both copper tube coils that can pass cooling water, and both ends are cooling water interfaces (4). To avoid interference, the axial pitch of the inner coil and the outer coil is 1.2-1.5 times the outer diameter of the copper tube cross section.

5. The inner and outer double coil induction heating structure of the special-shaped motor stator shrink sleeve according to claim 1 is characterized in that: In order to prevent the conflict of directions of magnetic fields generated by the inner and outer coils in the heating area, the inner coil (2) and the outer coil (3) have opposite rotation directions or the phase difference of the alternating currents passed is controlled to be π.

6. A gradient heating method based on the inner and outer double coil induction heating structure of the special-shaped motor stator shrink sleeve according to claim 1, characterized in that: During the heating process, a gradient heating method is used. When the maximum temperature of the shell reaches one-third and two-thirds of the target temperature, the power of the inner coil (2) and the outer coil (3) is adjusted to keep the shell warm for 60-100 seconds. After the insulation is completed, heating is continued at the initial power. When the maximum temperature of the shell reaches the highest value, the output power is adjusted to one-third of the initial value until the temperature difference between the highest temperature and the lowest temperature on the shell is within 10°C.

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