Preheating method of motor stator

Abstract

The present invention provides a method for preheating a motor stator, which can uniformly preheat the motor stator (1) and an injection mold (2) together in a short time by using simplified preheating equipment. The flange portion (22) of the injection mold (2) is arranged horizontally in a manner such that the main body (21) of the injection mold (2), including a long strip-shaped main body (21) and a flange portion (22) extending outward from one end of the main body (21) in the long side direction, faces upward. When the core (11) of the motor stator (1) is embedded in the cylindrical frame (13), the main body (21) of the injection mold (2) is inserted into the core (11) and one end of the frame (13) in the long side direction is placed on the flange portion (22). Next, a heat-insulating box (5) with an open lower surface is covered from above in a manner such that the frame (13) and the outside of the injection mold (2) are surrounded. An alternating current is passed through the coil (12) inside the box (5) to generate heat in the coil (12), thereby heating the core (11), the frame (13) and the injection mold (2).

Description

Technical Field

[0001] The present invention relates to a preheating method for a motor stator, wherein the motor stator comprises a core portion formed by laminating a plurality of annular electromagnetic steel plates, and coils wound in a plurality of slots formed at predetermined intervals on the inner periphery of the core portion. In the preheating method for a motor stator, the motor stator is preheated before molding the motor stator in which at least insulating resin is injected into a gap between the core portion and the coil and the resin is cured. Background Art

[0002] Conventionally, as a method for preheating such a motor stator, it is known to preheat the motor stator by supplying an alternating current to a coil to generate heat therein (for example, refer to Patent Document 1).

[0003] However, the following problem arises: it takes time to uniformly heat the inner and outer circumferences of the core to a predetermined temperature by energizing the coil. To solve this problem, in a preheating method for a motor stator described in Patent Document 1, a heater is provided at a location sandwiching the outer circumference of the core on at least one of the upper mold or the lower mold used during preheating, and the outer circumference of the core is directly heated by the heater, thereby shortening the preheating time.

[0004] However, in the preheating method for the motor stator described in Patent Document 1, the injection mold used for molding after preheating is not included in the preheating object. Therefore, there is a problem that the injection mold needs to be heated separately from the motor stator before or during molding. In addition, in the preheating method for the motor stator described in Patent Document 1, since a heater is required to directly heat the outer periphery of the coil in order to uniformly preheat the motor stator, there is a problem that the structure of the preheating device becomes slightly complicated.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2008-154348 Summary of the invention

[0008] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a method for preheating a motor stator which can uniformly preheat the motor stator and the injection mold together in a short time by using a simplified preheating device.

[0009] In order to solve the above-mentioned problems, the present invention relates to a preheating method for a motor stator, wherein the motor stator comprises a core formed by laminating a plurality of annular electromagnetic steel sheets, and a coil wound in a plurality of slots formed at a predetermined interval on the inner circumference of the core. In the preheating method for a motor stator, before the motor stator is subjected to molding in which at least an insulating resin is injected into a gap between the core and the coil and then cured, the motor stator is preheated, an alternating current is energized through the coil, and the motor stator is preheated by utilizing the heat generated by the coil. The method is characterized in that the motor stator comprises a strip The flange portion of the injection mold is horizontally arranged in a manner that the main body of the injection mold, including a shaped main body and a flange portion extending outward from one end of the main body in the long side direction, faces upward, and when the core of the motor stator is embedded in the cylindrical frame, the main body of the injection mold is inserted into the core and one end of the frame in the long side direction is placed on the flange portion. Next, a heat-insulating box with an open lower surface is covered from above in a manner that surrounds the outside of the frame and the injection mold, and an alternating current is passed through the coil inside the box to heat the coil, thereby heating the core, the frame and the injection mold.

[0010] According to the present invention, the heat generated by the coil is not only transferred to the inner periphery of the core inside the housing but also can be efficiently transferred to the outer periphery of the core, the frame and the injection mold, so that the motor stator and the injection mold can be uniformly preheated together in a short time. In addition, since the preheating can be completed using only the housing, the preheating equipment can be simplified.

[0011] In addition, in the present invention, it is preferred that after the coil is heated to the first predetermined temperature, the power is turned off, and the coil, the core, the frame, and the injection mold are all left until a second predetermined temperature suitable for the molding is reached. Accordingly, the coil can be powered for a shorter time, thereby improving the preheating efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a cross-sectional view schematically showing an embodiment of a method for preheating a motor stator according to the present invention.

[0013] Figure 2 The graphs respectively show the temperatures of the coil, the injection mold, the core, and the frame during preheating. DETAILED DESCRIPTION

[0014] Reference Figure 1, a preheating method of a motor stator according to the present embodiment is described. The motor stator 1 comprises: a core 11 formed by laminating a plurality of annular electromagnetic steel sheets (not shown), a coil 12 wound in a plurality of slots 11a formed at predetermined intervals on the inner periphery of the core 11, and a cylindrical frame 13. The core 11 is embedded in the frame 13 by shrink fit.

[0015] When the motor stator 1 is preheated, the injection mold 2 used for molding to inject at least insulating resin into the gap between the core 11 and the coil 12 (for example, the gap between the core 11 and the coil 12 in the slot 11a, the gap between the conductors forming the coil 12, etc.) and solidify it is also preheated. The injection mold 2 is a hollow mold, which includes: a long cylindrical main body 21, and a flange 22 extending outward from one end of the long side direction of the main body 21. When the motor stator 1 is preheated, the injection mold 2 is arranged horizontally with the flange 22 facing upward. In order to achieve such a stable horizontal arrangement of the flange 22, an annular adjustment plate (palette) 3 is used in this embodiment.

[0016] The adjustment plate 3 is provided with an opening 3a connected to the hollow portion 2a of the injection mold 2, and a plurality of pairs of heat insulating members 4 extending in a straight line in a radial direction passing through the center of the opening 3a are provided on the surface located outside the opening 3a. Each pair of heat insulating members 4 is arranged at a predetermined interval in the circumferential direction of the opening 3a. The flange portion 22 of the injection mold 2 is placed on all the pairs of heat insulating members 4 and arranged horizontally. In addition, the hollow portion 2a of the injection mold 2 and the opening 3a of the adjustment plate 3 are both portions for cooling the injection mold 2 together with the motor stator 1 by allowing a cooling medium such as air to flow after molding, and are not related to preheating.

[0017] In addition, when the motor stator 1 is preheated, the main body 21 of the injection mold 2 is inserted into the core 11, and one end of the frame 13 in the long side direction is placed on the flange 22 of the injection mold 2. Next, the box 5 with heat insulation and an open lower surface is covered from above in a manner that surrounds the outer side of the frame 13 and the injection mold 2. The box 5 has: an upper wall portion 51 and a side wall portion 52, and the upper wall portion 51 and the side wall portion 52 are both formed of a heat insulating member. There is no particular limitation on the material of the heat insulating member. In addition, a connector 53 that can be connected to a connector (not shown) for power supply provided at the lower end of the coil 12 is provided at the lower end of the box 5. When the box 5 is covered from above the frame 13 and the injection mold 2, the two connectors are connected. The connector 53 is connected to an AC power supply 6 for heating, and a control device 7 for controlling the power supply of the coil 12 is connected to the AC power supply 6.

[0018] When the coil 12 is energized with an alternating current from the AC power supply 6 via the control device 7, the coil 12 generates heat inside the housing 5, and the heat is transferred to the core 11, the frame 13, and the injection mold 2, thereby heating the core 11, the frame 13, and the injection mold 2. The lower end of the housing 5 is open, and there is a hollow portion 2a in the injection mold 2, and there is an opening 3a in the adjustment plate 3. Even so, in the space 5a of the housing 5, the air is heated along with the heating of the coil 12, but it does not circulate. In addition, since the injection mold 2 is arranged on the adjustment plate 3 via the heat insulating member 4, the heat generated by the heating of the coil 12 is not transferred to the adjustment plate 3.

[0019] Reference Figure 2 , showing Figure 1 An embodiment of a method for preheating a motor stator is shown in FIG. Figure 1 As shown, the core 11, the coil 12, the frame 13 and the injection mold 2 are respectively equipped with temperature sensors 8, and each temperature sensor 8 is connected to the control device 7 via the AC power supply 6 to measure the temperature of the core 11, the coil 12, the frame 13 and the injection mold 2. Regarding the installation position of the temperature sensor 8, on the coil 12, it is the upper end of the connector side and the upper end of the opposite side away from the connector half a circle, and on the injection mold 2, it is the upper end of the main body 21. In addition, although the figure is omitted, on the frame 13, it is the lower end.

[0020] The control device 7 supplies a high frequency power of 590 Hz and 1690 W from the AC power source 6, and the coil 12 is energized with an AC current of 23 A. Figure 2 As shown in the figure, after 20 minutes and 30 seconds, the temperature of the upper end of the energized side of the coil 12 reaches 150°C, which is the first specified temperature, and therefore, the energization of the coil 12 is disconnected by the control device 7. During the energization, temperature distribution caused by the difference in heat transfer degree etc. appears in the core 11, the coil 12, the frame 13 and the injection mold 2, but about 10 minutes after the energization is disconnected, the temperature of the core 11, the coil 12, the frame 13 and the injection mold 2 converges to 110°C, and this temperature convergence state continues as long as the box 5 is covered.

[0021] As described above, according to the preheating method of the motor stator 1 of the present embodiment, the heat generated by the heat generated by the coil 12 is not only transferred to the inner periphery of the core 11 inside the housing 5 but can also be efficiently transferred to the outer periphery of the core 11, the frame 13 and the injection mold 2, so that the motor stator 1 and the injection mold 2 can be uniformly preheated together in a short time. In addition, since the preheating can be completed using only the housing 5, the preheating equipment can be simplified.

[0022] In addition, according to the preheating method of the motor stator 1 of the present embodiment, after the coil 12 is heated to the first specified temperature, the power is disconnected, and the coil 12, the core 11, the frame 13 and the injection mold 2 are all placed until the second specified temperature suitable for molding is reached. As a result, the coil 12 only needs to be energized for a shorter time, thereby improving the preheating efficiency.

[0023] Although one embodiment of the present invention is described above, the present invention is not limited to the above embodiment. For example, the use of the adjustment plate 3 is arbitrary, and there is no particular limitation on the structure of the adjustment plate 3 when it is used. In addition, the adjustment plate 3 is not just fixedly set at the preheating position and remains unchanged, but can also be placed on a conveying mechanism such as a roller conveyor and move freely, and automatically move to the molding process after preheating. In addition, there is no particular limitation on the shape and structure of the injection mold 2.

[0024] Description of Reference Numerals

[0025] 1 ... motor stator; 11 ... core; 11a ... slot; 12 ... coil; 13 ... frame; 2 ... injection mold; 21 ... main body; 22 ... flange; 5 ... housing.

Claims

1. A method for preheating a motor stator, the motor stator comprising a core formed by laminating a plurality of annular electromagnetic steel sheets, and a coil wound in a plurality of slots formed at predetermined intervals on an inner circumference of the core, wherein the motor stator is preheated before molding the motor stator by injecting at least an insulating resin into a gap between the core and the coil and curing the insulating resin, The coil is energized with alternating current, and the heat generated by the coil is used to preheat the motor stator. It is characterized in that The flange portion of the injection mold is horizontally arranged in a manner that the main body of the injection mold, including a long cylindrical main body and a flange portion extending outward from one end of the main body in the long side direction, faces upward, and the flange portion of the injection mold is horizontally arranged in a manner that: when the core portion of the motor stator is embedded in the cylindrical frame, the main body of the injection mold is inserted into the core portion and one end of the frame in the long side direction is placed on the flange portion, and the flange portion of the injection mold is placed on all pairs of heat insulating parts of the annular adjustment plate, wherein the annular The adjustment plate is formed with an opening connected to the hollow portion of the injection mold, and on the surface located on the outer side of the opening, a plurality of pairs of thermal insulation members are provided, which extend in straight lines in a radial direction passing through the center of the opening, and each pair of thermal insulation members is arranged at a specified interval in the circumferential direction of the opening; next, a box having thermal insulation properties and an open lower surface is covered from above in a manner so as to surround the outer side of the frame and the injection mold, and an alternating current is passed through the coil inside the box to heat the coil, thereby heating the core, the frame and the injection mold.

2. The method for preheating a motor stator according to claim 1, characterized in that: After the coil is heated to the first predetermined temperature, the power is turned off, and the coil, the core, the frame, and the injection mold are all left until they reach a second predetermined temperature suitable for the molding.

Images