JP2008092733A - Heating method of winding for rotary electric machine, and processing unit to apply this heating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To evenly heat a winding for a short time in a series of processes in which the winding is impregnated with varnish and is hardened in manufacturing of a rotary electric machine. <P>SOLUTION: In an induction heating method of the winding for the rotary electric machine using power supply of a frequency which is higher than commercial power supply, a heating coil is used, wherein the heating coil is wound so that a direction perpendicular to a central axis of a radial direction of an annular body may become an axial direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to the manufacture of rotating electric machines such as electric motors, generators, and motor generators, and more particularly to a technique for fixing windings of rotating electric machines by varnish impregnation and curing.

  During the manufacturing process of stators of rotating electrical machines such as electric motors and generators, varnish is applied to the windings for the purpose of improving the insulation of the inserted windings, improving seismic resistance, oil resistance, chemical resistance, heat dissipation, etc. There is a varnish impregnation step of dripping impregnation and curing. In addition to the varnish dropping step, the varnish impregnation step includes a preheating and a heat treatment step for curing as a pretreatment and post-treatment heat treatment step.

  Known conventional heating methods include hot air heating using a hot air circulating furnace, direct heating using direct energization or induction heating, and the like. In the heating by the hot air circulating furnace, heating is performed by heating the air as a heating source from the surface after heating the air using the heater as a heat source.

In addition, in the heating by induction heating, the winding or the metal ring around which the winding is wound directly receives the magnetic field generated by the AC power source from the heating coil installed around the winding. In the metal, an eddy current is generated by this magnetic field, and the metal part directly generates heat due to the Joule heat. For this reason, there exists an advantage that the temperature increase rate of a workpiece | work is quick.
JP 2006-035831 A

  However, in the heating by the hot air circulation furnace, it takes a long time to surely heat the coil end and the coil inside the slot, which are deep parts of the work, and in particular, to heat the varnish, it takes a long time of 1 to 2 hours. It takes time. In continuous processing, the length of the furnace becomes very long regardless of the production volume. When a quality defect in the varnish process is found in a subsequent process, a large number of products processed in the same manner are treated as defective. Since this defective product cannot be corrected in a later process, it must be discarded, resulting in a lot of product loss. The curing process of the varnish is managed by the temperature of the heated air. However, in the temperature management of the heated air, the temperature applied to the actual winding is unknown, and the varnish curing state cannot be grasped in detail.

  In induction heating, when the distance between the heating coil and the workpiece is increased, the magnetic field does not reach the workpiece and the workpiece does not generate heat at all. For this reason, in the conventional heating coil, a coil is manufactured by winding a conductive wire around the outer periphery of a cylindrical bobbin concentric with the central axis in the radial direction of the ring body, and the distance between the workpiece and the coil is minimized.

  However, depending on the application, accessory parts such as the connection terminal portion of the workpiece extend in the radial direction from the ring body. In such a case, it is necessary to increase the inner diameter of the cylindrical bobbin so as not to interfere with the accessory parts. However, if the distance between the workpiece and the heating coil becomes too large, the workpiece does not generate heat and induction heating is applied. become unable. In addition, if a cylindrical heating coil is used for heat treatment after dropping the varnish, the varnish falls from the lower side of the winding, and the varnish that has fallen is deposited and hardened, damaging the heating coil or colliding with the workpiece. It may be damaged or the apparatus transport unit may be damaged, and normal operation becomes impossible. A hot air heating system such as a hot air circulating furnace has been used for winding heating in such cases.

  The ring body is, for example, a cylindrical shape formed by laminating a plurality of donut-shaped electrical steel sheets (punched by pressing), and has a plurality of slots on the inner periphery. In this case, a winding is wound from one slot to an adjacent slot, which is sometimes referred to as a core or the like. FIG. 1 shows an example of an annulus and windings. A combination of this ring and winding is called a workpiece.

  The present invention has been devised in view of the above circumstances, and in a series of steps of impregnating and curing a varnish in a winding in the manufacture of a rotating electrical machine, heating the winding uniformly in a short time. Is the main purpose.

The present invention relates to the following.
(1) In a method of induction heating of a rotating electrical machine winding using a power source having a frequency higher than that of a commercial power source, rotation using a heating coil wound so that the direction perpendicular to the radial central axis of the annulus is the axial direction Heating method for electric windings.
(2) The heating method for a rotating electrical machine winding according to item (1), wherein the cross-sectional shape of the thermal coil is such that at least two sets of upper and lower two sides entering the winding are not the same length.
(3) A heating method for a rotating electrical machine winding according to item (1) or (2), wherein the heating coil is divided into two parts with respect to the central axis in the radial direction of the annular body.
(4) In a method of induction heating a rotating electrical machine winding using a high frequency power supply higher than a commercial power supply, a heating coil wound in a flat plate shape in a direction perpendicular to the radial central axis of the ring is used. Heating method for rotating electrical machine windings.
(5) A processing apparatus using the heating coil according to any one of claims 1 to 4, wherein the rotary electric machine winding is preheated and then dripped and impregnated with varnish and cured by heat treatment.

  In the configuration described in (1) above, unlike a cylindrical heating coil, even if a sufficient radial distance is provided between the heating coil and the work ring, the distance can be shortened in the direction perpendicular to the radial direction facing the ring. Therefore, the magnetic field generated by the AC power supply can be sufficiently transmitted to the workpiece. Further, when used in a curing furnace, if the opening direction of the heating coil is made to coincide with the direction in which the varnish falls off the workpiece, the varnish will not be deposited on the heating coil.

  In addition, as in the invention described in (2), if the cross-sectional shape of the heating coil is not the same in the length of the upper and lower sides entering the winding but is trapezoidal, the coil can be formed even if the number of coil turns is increased. The total length of the electric wire used can be shortened, and the impedance of the heating coil can be lowered. As a result, a current flowing through the heating coil can be secured and heat can be generated. If the impedance becomes too high, the current flowing through the heating coil decreases, and a predetermined heating amount cannot be obtained.

  As in the invention described in (3), if two heating coils that are divided into two with respect to the central axis in the radial direction of the annular body are used, for example, the heating rate of the workpiece can be increased compared to the case of the same shape. It can be about twice as fast.

  As in the invention described in (4), when a heating coil wound in a flat plate shape in a direction perpendicular to the radial center axis of the annular body is used, the heating coil can be brought close to the workpiece regardless of the radial distance. it can. Also, there is no varnish accumulation due to dripping from the workpiece.

  If the heating coil according to any one of (1) to (3) is used as in the invention described in (5), after preheating the rotating electrical machine winding, the varnish is dropped and impregnated and cured by heat treatment. A suitable varnish processing apparatus can be obtained.

  The process of dripping impregnating and curing the varnish on the winding of the rotating electrical machine in the present invention will be described according to the following example. As illustrated in FIG. 2, in this step, the work is first conveyed into the apparatus and held by a method such as an inner diameter chuck. In general, since the inner diameter chuck incorporates a rotation mechanism, the workpiece rotates during conveyance. A workpiece | work enters a preheating part of a next process from a receiving part. In the preheating unit, the work is heated by induction heating.

  FIG. 3 schematically shows preheating of the workpiece by induction heating. The workpiece 1 is held by a shaft 10 with an inner diameter chuck that supports the inner diameter of the annular body. The shaft 10 is moved by a transport mechanism 11 having a rotation mechanism, and is transported to a predetermined position where the heating coil 13 of the preheating chamber 12 is present. The heating coil 13 is moved to a predetermined position around the workpiece 1 by the back-and-forth moving mechanism 14.

FIG. 4 illustrates a cylindrical coil that has been conventionally used for heating. The cylindrical coil is disposed so as to surround the outer periphery of the work, and at the same time, the coil is wound along the circumferential direction. When a current flows through the coil by an AC power supply, a magnetic field is generated around the coil. The magnetic field is generated in a direction penetrating the metal work ring and the winding, and an eddy current is generated in the ring and the winding. The work generates heat due to the Joule heat of the eddy current. If the work rotates, the relative position between the magnetic field and the work changes, so heat generation is performed more uniformly.
On the other hand, depending on the work, accessory parts such as connection terminals extend from the ring body in the radial direction. In this case, when a conventional cylindrical heating coil is used, the distance between the workpiece and the heating coil is too large. As a result, the gap length of the magnetic path becomes excessive, the current is drastically reduced, and the workpiece cannot be heated. According to the present invention, the workpiece can be heated by bringing the heating coil closer to the workpiece from a plane perpendicular to the diameter.
The heating coil 16 shown in FIGS. 5 to 9 is formed so as to penetrate vertically and is designed so that the axial distance between the workpiece and the heating coil becomes small.

  The heating coil shown in FIGS. 10 to 12 has a method of heating from one axial direction with few projections and the like. In this case, when a heating coil is installed on the opposite side of the inner diameter chuck, the disc coil shown in FIG. 10 can be used. On the other hand, when a heating coil is installed on the inner diameter chuck side, a notched disk heating coil shown in FIG. 12 with the shaft of the inner diameter chuck removed is suitable. In any of the disk coils, it is preferable that one disk heating coil is formed of a coil having one or a plurality of winding centers of the conductive wire.

  In the next step, the work is dripped and impregnated with varnish. The varnish is dripped from a nozzle installed in the vicinity of the coil end of the winding 3 on both sides of the rotating workpiece, and the varnish is impregnated and impregnated throughout the winding by capillary action. The impregnated varnish is cured in the next step. In the varnish curing step, curing has conventionally been performed by hot air heating. This is because the solvent etc. evaporates in the curing process of the varnish, the use atmosphere becomes a solvent atmosphere and this ignites, and when using a cylindrical coil, the varnish dripping from the work adheres to the coil. Because there is a problem.

  Regarding safety, when induction heating is used in a solvent atmosphere, for example, attention must be paid to ignition from an energized heating coil. To cope with this danger, for example, ventilation in the furnace must be sufficiently performed. For example, it is important to control the atmospheric concentration of the solvent generated from the varnish and keep it at a level well below the explosion limit. As for other heating coils, it is useful from the viewpoint of preventing ignition if, for example, a method disclosed in Japanese Patent Application Laid-Open No. 2004-127546 is used. In connection with the connection of the heating coil terminal, it is also useful from the viewpoint of preventing ignition to extend the coil terminal wire to a safe part, create a terminal box at the place, and perform a chisso purge of the terminal box for safety. Enamelled stranded wire such as litz wire is often used for the wire that forms the coil. In this case, the wire is insulated with a glass fiber tube, etc., and then the two wires are joined together to form a terminal box Wiring up to is good. It is preferable to use more litz wires in the wiring when extending the coil terminal wires. This is because the current flowing in the opposite direction at the wiring passage part works in a direction in which the magnetic fluxes cancel each other, and induction heating can be suppressed.

  Depending on the workpiece shape, the magnetic field generated from the manufactured heating coil may not reach the ring body and the windings sufficiently, and power output may not be obtained. In this case, for example, if a rod-shaped ferrite is installed on the surface of the conductor with an angle of 50 to 90 degrees with respect to the coil conductor, a magnetic path is secured and a power output is obtained. Ideally, the angle of the ferrite should be radial so that it goes toward the central axis with respect to the ring body and close to 90 degrees with respect to the conductive wire. It is preferable to determine the angle within a range of 50 to 90 degrees with respect to the conducting wire. If this angle cannot be set appropriately, it is preferable to change the coil conductor as much as possible along the circumferential direction of the ring body, since the output increases.

  It is effective to apply the heat treatment in the present invention to part or all of the preheating step of the winding in the step of impregnating the varnish into the winding of the rotating electrical machine and curing, and the varnish curing heat treatment step of impregnating the winding. It is.

  An outline of the heating mode of the workpiece 1 in the present invention is illustrated in FIG. The workpiece 1 is held by a shaft 10 with an inner diameter chuck, and is moved to a predetermined position in the heating chamber 12 by a transfer device 11 with a rotation mechanism. A heating coil 16 is disposed above the predetermined position, and the heating coil 16 is lowered to a predetermined position of the workpiece 1 by the vertical mechanism 17. The heating coil 16 rises after the heating is completed, and the work 1 moves to the next position.

  6 and 7 schematically show the heating coil 16 manufactured according to the present invention installed on the workpiece 1 from the front and plane. The heating coil was created by winding a litz wire around a bobbin made of a rectangular parallelepiped FRP that vertically penetrated. The impedance of the heating coil measured at 20 kHz was 38 μH. As shown in the plan view 7, the work and the heating coil can maintain a sufficient distance in the radial direction while maintaining a sufficiently close distance in the perpendicular direction. When an AC power supply with a frequency of 30 KHz and an output of 10 KW was connected to the heating coil, an output of 15% was obtained and the workpiece could be heated. If the penetration part of this heating coil is taken in the vertical direction, it is possible to prevent the varnish from dripping from the dropped work. On the other hand, a conventional cylindrical coil was manufactured with the inner diameter of FIG. The impedance of the produced cylindrical coil was 34 μH by the same measurement method. This heating coil was connected to the same power source and heating was studied. However, the coil had an excessively long magnetic path, and the current was drastically reduced, so that heating was not possible.

FIG. 8 shows a trapezoidal heating coil in which the lengths of the upper and lower sides are different. In this trapezoidal coil, since the length per turn can be reduced, the number of turns can be 1.3 times the number of turns of the rectangular coil of FIG. For this reason, the energization amount to the heating coil was able to increase about 30% of the rectangular coil.
FIG. 9 is an example in which two trapezoidal coils are used, and is apparently divided into two parts with respect to the center axis of the annular body. In the arrangement of this example, the energization amount of the AC power source could be improved to about 200% compared to one trapezoid coil. When the coils are properly combined, the magnetic path is secured and the electric power effective for heating is about doubled.

  10 and 11 are examples using a disk-shaped coil. The disk-shaped coil is formed so as to be applied to the ring body and the winding around the center axis of the ring body. For example, the coil is not formed in the center portion where there is no workpiece. When this disk coil was placed on the side surface of the workpiece winding and turned on with an AC power supply, the temperature could be raised to the target temperature in 20 minutes.

FIG. 12 shows an example in which a notched disk coil is used. Since this coil cannot be wound in a concentric manner around the center axis of the annular body, the coil is divided into three blocks and wound with a size suitable for each block. The disk coil was not close enough to the workpiece with the terminals coming out, and the workpiece could not be heated even when AC power was turned on. Since this notched disk coil was sufficiently close to the workpiece from the support shaft side, the workpiece could be heated with an AC power supply.
In the present invention, the heating coil may be formed such that the cross-sectional shape of the heating coil is not only a straight line but also a side in the workpiece entry direction is an arc, and the coil conductor is along the circumferential direction of the annular body.
Further, not only when the workpiece is held by the inner diameter chuck, but also when the workpiece is held by the outer shape chuck or held flat, the workpiece can be heated by using the disk coil.
In FIGS. 4 and 6 to 9, the windings are omitted and shown, and in FIGS. 3 and 5 to 12, the conductive wire of the heating coil is omitted and shown.
The present invention can be widely applied to a stator or a rotor of a general multiphase rotating electrical machine, and can be applied to heating of windings in, for example, a three-phase induction motor or a generator.

It is a section explanatory view of a work. It is explanatory drawing of a varnish impregnation process. It is a block diagram which shows the outline of the conventional varnish impregnation apparatus heating part. It is an example of the conventional cylindrical heating coil. It is the example of a block diagram which shows the outline of the varnish impregnation apparatus heating part by this invention. It is a front view which shows the outline of the heating coil by this invention. It is a top view which shows the outline of the heating coil by this invention. 1 is a schematic example of a trapezoidal heating coil according to the present invention. 2 is a schematic example of using two trapezoidal heating coils according to the present invention. It is an outline example of the disc heating coil simple substance by the present invention. It is an outline example of the disc heating coil by the present invention. 1 is a schematic example of a notched disk heating coil according to the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Work, 2 ... Ring, 3 ... Winding, 10 ... Shaft, 11 ... Conveying device, 12 ... Heating chamber, 13 ... Heating coil (conventional), 14 ... Back-and-forth movement mechanism, 16 ... Heating coil, 17 ... Up and down mechanism.

Claims (5)

  In a method of induction heating a rotating electrical machine winding using a power source having a frequency higher than that of a commercial power source, a heating coil wound so as to have a direction perpendicular to the radial central axis of the ring as an axial direction is used. Heating method for rotating electrical machine windings.   2. The method of heating a rotating electrical machine winding according to claim 1, wherein the cross-sectional shape of the heating coil is such that at least two sets of upper and lower two sides entering the winding are not the same length.   3. A method of heating a rotating electrical machine winding according to claim 1, wherein the heating coil is divided into two parts with respect to the central axis in the radial direction of the annular body.   In a method of induction heating a rotating electrical machine winding using a high frequency power source higher than a commercial power source, a rotating electrical machine winding characterized by using a heating coil wound in a plate shape in a direction perpendicular to the radial central axis of the ring Wire heating method.   A processing apparatus using the heating coil according to any one of claims 1 to 4, wherein the heating coil is preliminarily heated and thereafter dripped and impregnated with varnish and cured by heat treatment.

Images