JPH08289510A - Method and apparatus for hardening coil insulating layer - Google Patents

Abstract

PURPOSE: To provide a method and an apparatus for hardening a coil insulating layer, which can improve the insulating characteristic of the coil insulating layer for electric machine formed by using thermosetting resin. CONSTITUTION: Respective coils 1a...1n are compressed with compressors 2a...2n and heated. Thermosetting resin is hardened, and an insulating layer is formed. In this step, the change in capacitance of the coil measured with a capacitance measuring device 11 is monitored by a controller 12. At the time when the capacitance of each coil becomes the maximum value, tightening is performed with the compressors 2a...2n corresponding to the respective coils 1a...1n. Thereafter, the capacitance is decreased. The monitoring is continuded, furthermore. At the time when the predetermined control value is reached, the heating is stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a coil for an electric machine,
The present invention relates to a method and a device for hardening an insulating layer formed by using a thermosetting resin, and particularly to a method and a device for hardening a coil insulating layer capable of improving the insulating performance of a manufactured coil.

[0002]

2. Description of the Related Art Pressure is applied to a coil semi-finished product in which a tape containing a solid insulating material is wound around a coil conductor to impregnate a thermosetting resin, or a semi-cured prepreg tape made of these materials is wound. In the method of forming an insulating layer by heating and curing while adding it, heat it to some extent in the curing process in order to eliminate voids that occur during resin impregnation and winding of prepreg tape, and to make an insulating layer with high insulation performance and reliability. , When the viscosity of the impregnated resin decreases, it is called retightening.
A step of increasing the pressure applied to the insulating layer is provided. After the retightening, the heating state is continued, and the resin is cooled after the completion of curing of the resin.

Conventionally, prior to heating and hardening the coil body, the monitor sample is hardened, and the viscosity of the sample is mechanically measured while sampling the resin, and the temperature and time conditions at which the viscosity becomes the minimum are grasped. Was there. Then, only the temperature was monitored when the coil body was heated and cured, and the coil body was retightened at the same temperature and time history as the monitor sample. In the same manner, the change in hardness of the monitor sample was used as an index for cooling.

[0004]

The method for determining the tightening and cooling timings described above is an indirect method and does not directly monitor the resin viscosity of the coil body.
Even if there is a difference in the temperature history between the monitor sample and the coil body, the tightening and cooling timings cannot be adjusted, and the optimum timing may not be selected. As a result, the insulation performance of the coil produced is not stable and must be designed with a large margin for the performance of the insulation layer produced under optimal conditions, consuming more resources than necessary. It was one of the causes.

The present invention has been made in view of the above circumstances, and in response to the deviation of the hardening progress of the thermosetting resin layer due to the variation of the temperature history of the coil, the tightening is always performed at the optimum timing. It is an object of the present invention to provide a coil insulating layer curing method and device that can stably manufacture a coil for an electric machine having high insulation performance with a small variation by cooling.

[0006]

In order to achieve the above object, in the coil insulating layer curing method and apparatus of the present invention, the viscosity of the resin forming the insulating layer of each coil body is monitored during the curing process. It is configured such that the tightening is performed when the minimum viscosity is reached, and the heating of the coil body is ended when the curing is completed. Also, as a method to detect the change in resin viscosity, instead of the conventional mechanical measurement by partial sampling from a monitor sample, focus on the capacitance of the insulating layer as an electrical characteristic that changes depending on the viscosity. Then, the method of measuring this was adopted.

[0007]

In the present invention, since the viscosity of the resin of the coil body, which is not the monitor sample, is directly monitored, the optimum tightening and cooling timing can always be selected. In addition, since viscosity changes are detected by non-destructive electrical means called changes in electrostatic capacity, it is possible to manage all individual coils when manufacturing multiple coils, and variations in temperature history between coils There is no variation in insulation characteristics due to

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the construction of an embodiment of a coil insulating layer curing device according to the present invention. This example is an example in which n coils of the coils 1a, 1b, ..., 1n are manufactured at the same time. In FIG. Switching device 10
And a capacitance measuring device 1 for measuring the capacitance of each coil
1. It has a control device 12 that controls each part in a centralized manner and a pressurization control device 13 that controls the pressurizing devices 2a, 2b, ..., 2n. Although not shown, the coils 1a, 1b,
1n is equipped with a heating element for heating, or the coils 1a, 1b, ..., 1n are housed in a temperature-controlled curing furnace. For this temperature management, a temperature detector 14 to which a temperature sensor (not shown) is connected and a temperature controller 15 are provided, and these are both connected to the controller 12.

The coil insulating layer curing device having the above structure operates as follows. 1n are tightened in advance by pressurizing devices 2a, 2b, ..., 2n, respectively. The capacitance of each coil 1a, 1b, ..., 1n is measured by the capacitance measuring device 11 via the switching device 10,
The measurement result is sent to the control device 12.

In the control device 12, the coils 1a, 1b, ...
A capacitance of 1 n is sequentially recorded from the start of heating and is monitored for each coil. When it is determined that any coil (here, for example, the coil 1i) has reached the appropriate time for the tightening (the determination method will be described later), the controller 12 performs the tightening on the pressurizing controller 13. Issue a command to make it happen. The pressurization control device 13 that receives this command causes the coil 1
A command to start tightening is issued to the coil pressurizing device 2i corresponding to i, and the coil pressurizing device 2i starts pressurizing the coil 1i.

Further, when it is determined that the curing of the resin is completed (a determination method will be described later), the controller 12 outputs a command to stop heating to the temperature controller 15.

Here, as the control device 12, for example, a digital computer is suitable. Capacitance measuring device 1
As 1, a general-purpose C meter, L, C, R meter, impedance meter or the like can be used. Pressure device 2a, 2
A hydraulic pressurizing device or the like can be used as b, ..., 2n.

Next, an example of a method for determining the tightening and cooling timing will be described. As the viscosity of the resin, which is a dielectric material, decreases, the force that restrains the movement of the electric dipole corresponding to the electric field decreases, and the dielectric constant increases. That is, when the area of the electrodes and the distance between the electrodes are the same, the capacitance becomes large. The viscosity of the thermosetting resin is considerably high in the initial stage of its curing, but when heated, it initially decreases as the temperature rises. On the other hand, as the heating progresses, the viscosity gradually increases, and the viscosity increases. Corresponding to this, the electrostatic capacity rises once after heating and then drops. Here, the peak time of the capacitance coincides with the minimum time of the viscosity, which is the optimum timing for tightening the coil.

The control device 12 controls the coils 1a, 1b,
... By tracking the change in the capacitance value for each 1n, it is possible to identify the time point at which the increase in the capacitance value stops and then shifts to the decrease for each coil. The pressurizing control device 13 may be controlled so that the command is output from the pressurizing control device 13 to the corresponding pressurizing device. After this, if the heating is continued and the curing of the resin is completed, the capacitance value of the corresponding coil will be equal to or less than the value at the start of heating, so record the initial value at the start of heating and compare it with this. It is possible to determine the completion of curing of the resin forming the insulating layer of the corresponding coil.

FIG. 2 shows an example of a temporal change in capacitance of the actual coil during curing, and FIG. 3 shows an example of a temporal change in coil temperature simultaneously measured. In this example, a coil having a rated voltage of 6.6 kV and a length of a portion to be incorporated in the core of about 1 m was measured with an electrode area for measuring the capacitance of about 100 cm ² . Figure 2
The point X in the figure is the maximum point of the electrostatic capacity and the minimum point of the viscosity, that is, the optimum timing of the tightening. If heating is continued after the time point X, curing proceeds and the capacitance decreases. Then, when the curing is completed, the capacitance becomes equal to or less than that before the heating is started, and even if the heating is continued beyond this, the thermal deterioration progresses. As seen from the temperature history of FIG. 3, the optimum timing of the tightening occurs during the temperature rise, and thereafter, the temperature is kept rising to the upper limit where thermal deterioration can be avoided, and the curing is completed. At that point, heating has ended.
By thus monitoring the capacitance of the coil, both timings of tightening and heating can be optimally selected.

The advantages of the curing management method according to this embodiment are as follows. First, by directly controlling the viscosity of the resin that is injected and impregnated into the coil body that is the target of control, or the resin that is contained in the wound prepreg tape, the monitor sample and coil body that cause an error when managing with the monitor sample There is no influence of the difference in temperature history. Of course, since the monitor sample is not necessary, it is possible to save the trouble of grasping the characteristics of the monitor sample in advance, and there is no waste of the monitor sample.

Since the viscosity control is non-destructive and can be performed easily electrically, it is easy to control the total number, and even when curing a large number of coils at the same time, the optimum control that reflects the variation in the temperature history of each coil is performed. It can be performed. That is, even if there are differences in the temperature history characteristics of individual coils due to variations in the characteristics of the heaters that heat the coils, the placement of heaters in the curing furnace, and differences in position, etc., each coil is retightened under optimum conditions. You can set the timing.

In carrying out the present invention, an embodiment for measuring the capacitance will be described below. FIG. 4 shows a cross section in which a part of the coil 1 being heat-molded is disassembled. In the figure, the coil 1 comprises a coil internal conductor 21 and a resin insulating layer 22 which surrounds the coil internal conductor 21 and is made by mixing a solid or glassy insulating material with a thermosetting resin or the like. Here, the coil inner conductor 21 is used as one electrode, and the molding plates 23a, 23b, 23c, and 23d arranged with the resin insulating layer 22 separated are used as the other electrodes, and the lead wires 3 and 3'are led out from both electrodes. Coil 1
Will measure the capacitance of. Molded plate 23
Since a, 23b, 23c, and 23d are tightened, they are often electrically connected, and the capacitance measured at this time is the total sum of the insulating layers. Temporary molding plate 23
When all or part of a, 23b, 23c, and 23d are electrically independent, the capacitance of the portion in contact with the contact plate connected to the lead wire 3'is mainly measured. In the present invention, attention is paid to the change in capacitance, and the absolute value does not matter, so either may be used.

In many cases, the inner conductor 21 of the coil 1 is not a single conductor but an aggregate of a plurality of conductors insulated from each other. In this case, it is preferable that the conductors are electrically short-circuited at the ends of the coil so that the whole can be regarded as one electrode having the same potential. As this method, it is common to peel off the insulating coating of each strand at the end and short-circuit with a conductor, etc., but apply a conductive paint to the end face of the coil so that it extends over each strand, A method of applying putty may be used.

In FIG. 4, the molding plates 23a, 23b,
When 23c and 23d are at the ground potential, the lead wire 3'on the ground potential side may be omitted. Also, the molding plate 23
When a, 23b, 23c, and 23d are at the ground potential, and it is difficult to measure the capacitance by single-line grounding, the configuration shown in FIG. 5 can be adopted. That is, a conductive layer 24 is provided on the outer circumference of the coil insulating layer 22, and this is connected to the lead wire 3'as one electrode for measuring capacitance. A heat-resistant insulating layer 25 capable of withstanding the maximum temperature in the curing process is formed between the molding plates 23a, 23b, 23c, 23d.
Is provided to provide insulation to ground. In this case, the heat-resistant insulating layer 25 has only to withstand a few volts, which is the applied voltage when measuring the capacitance.

FIG. 5 shows an example in which a conductive foil or conductive tape is wound as the conductive layer 24 and an insulating foil or insulating tape is wound as the insulating layer 25 around the entire outer circumference of the insulating layer 22.
Instead of these, a single plate-shaped conductor plate or insulating plate may be provided only on the flat portion excluding the corner portions. In this case, the present invention can be implemented by arranging the flat portion on at least one of the four flat portions.

As a modification of the present invention, there is a method of accelerating the curing of the coil itself or the resin forming the insulating layer of the coil by utilizing the residual heat of the heater or the curing furnace. When the coil, the heater, the curing furnace, etc. have a large amount of residual heat, they are not immediately cooled even if the heating is stopped, and the curing of the uncured resin proceeds. Therefore, by anticipating this effect and stopping heating early, the energy required for heating can be reduced,
Further, there is an effect that it is possible to prevent the progress of thermal deterioration caused by heating more than necessary. In this method, in the electrostatic capacity history characteristic shown in FIG. 6, the index value Cs is set in consideration of the decrease in the electrostatic capacity due to the residual heat after the heating is stopped, and the observed electrostatic capacity value is set to this value. This can be realized by outputting a heating stop command from the temperature control device 15 in FIG. Note that FIG. 6 shows an electrode area of about 100c for a coil with a rated voltage of 6.6kV.
This is an example measured at m ² .

As another embodiment of the present invention, there is a method of monitoring the loss coefficient or impedance in addition to the capacitance as an index for grasping the curing state of the resin forming the insulating layer of the coil. With this method as well, a coil having good insulation characteristics can be manufactured as in the method of monitoring the electrostatic capacitance described above. In addition, when the loss coefficient is monitored, the characteristic that the specific resistance of the resin increases with temperature is also evaluated. Therefore, in many cases, the loss coefficient shows a peak before the electrostatic capacity shows a peak in the temperature rising process, and there is an effect that it can be used as a notice signal of the optimum tightening timing.

Further, in the method of monitoring impedance, a single-function impedance measuring instrument having no analysis function such as capacitance can be used.

[0026]

According to the present invention described above, in the step of heating and hardening the resin forming the insulating layer of the coil of the electric machine, the progress of hardening is determined by the electrical non-destructive characteristics of the resin,
In particular, since it is possible to determine the timing of pressurization and end of heating by grasping the change in capacitance, the resin that forms the insulating layer is always cured under optimal conditions. Can be manufactured.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a coil insulating layer curing device according to the present invention.

FIG. 2 is a diagram showing a measurement example of a change with time of the capacitance of the coil insulating layer when the coil insulating layer is cured by the insulating layer curing method of the present invention.

FIG. 3 is a diagram showing an example of measurement of changes over time in temperature of a coil insulating layer when the coil insulating layer is cured by the insulating layer curing method of the present invention.

FIG. 4 is an explanatory diagram showing an example of a cross-sectional structure of a coil cured by the insulating layer curing method of the present invention.

FIG. 5 is an explanatory diagram showing another example of the cross-sectional structure of the coil cured by the insulating layer curing method of the present invention.

FIG. 6 is a diagram showing a time-varying characteristic of electrostatic capacity for explaining another example of the insulating layer curing method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 coil 1a coil 1b coil 1i coil 1n coil 2a pressurizing device 2b pressurizing device 2i pressurizing device 2n pressurizing device 3 lead wire 3'lead wire 10 switching device 11 capacitance measuring device 12 control device 13 pressurizing control device 14 Temperature Detector 15 Temperature Control Device 21 Coil Inner Conductor 22 Resin Insulation Layer 23a Molding Plate 23b Molding Plate 23c Molding Plate 23d Molding Plate 24 Conductive Layer 25 Insulating Layer

Continued Front Page (72) Tohru Koyama 7-1-1 Omika-cho, Hitachi City, Hitachi, Ibaraki Prefecture Hitachi Research Laboratory, Hitachi Ltd. (72) Hiroyuki Kamiya 3-1-1, Saiwaicho, Hitachi City, Ibaraki Prefecture Hitachi Ltd., Hitachi Works (72) Inventor Mitsuru Onoda 3-1-1, Saiwaicho, Hitachi City, Ibaraki Prefecture Hitachi Ltd., Hitachi Works (72) Inventor Nobuaki Furukawa 3-chome, Sachimachi, Hitachi City, Ibaraki Prefecture 1st-1 Hitachi Ltd. Hitachi factory (72) Inventor Yoichi Kotani 3-1-1 1-1 Saiwaicho, Hitachi City, Ibaraki Hitachi Ltd Hitachi factory

Claims (4)

[Claims] 1. A coil insulating layer curing method for producing a coil for an electric machine by pressurizing and heating a thermosetting resin layer containing an insulating material formed around a conductor to cure the resin, From the start of the heating and curing, the electrical properties that are correlated with the viscosity of the resin layer are measured, and the changes over time in the measured values are monitored,
A method for curing a coil insulating layer, which comprises increasing the pressure applied to the resin layer when the measured value reaches a value at which the resin layer has the minimum viscosity, and stopping the heating when the curing of the resin layer is completed. 2. A coil insulation layer curing method for producing a coil for an electric machine by pressurizing and heating a conductor formed with a thermosetting resin layer containing an insulating material around the conductor, Measure the capacitance of the resin layer from the start of heating and curing,
The time-dependent change of the measured value is monitored, and the pressing force of the resin layer is increased at the time when the measured value of the electrostatic capacitance becomes maximum, and then the electrostatic capacitance value is decreased to a predetermined value at the start of heating. A method for curing a coil insulating layer, characterized in that heating is stopped at. 3. A heating means for heating a coil body on which a thermosetting resin layer containing an insulating material is formed around a conductor, a pressurizing means for pressurizing the coil body, and controlling the heating means and the pressurizing means. In a coil insulation layer curing device for producing a coil for an electric machine by pressurizing and heating the coil body to heat the resin layer to control the resin layer of the coil body in a heat curing step. It has an electrical characteristic measuring means for measuring an electrical characteristic having a correlation with viscosity, the control means takes in the measurement result of the electrical characteristic measuring means, and the electrical characteristic of the resin layer from the start of heating and curing. Of the measured value of the resin layer is monitored over time, and when the measured value reaches a value at which the resin layer has the minimum viscosity, the pressing force of the resin layer is increased, and heating is stopped when the curing of the resin layer is completed. To the heating means Coil insulating layer curing apparatus characterized by controlling the pressurizing means. 4. A heating means for heating a coil body on which a thermosetting resin layer containing an insulating material is formed around a conductor, a pressure means for pressurizing the coil body, and the heating means and the pressure means are controlled. In a coil insulation layer curing device for producing a coil for an electric machine by pressurizing and heating the coil body to heat the resin layer to control the resin layer of the coil body in a heat curing step. Having a capacitance measuring means for measuring the capacitance, the control means takes in the measurement result of the capacitance measuring means, changes with time of the measured value of the capacitance of the resin layer from the start of heating and curing. Is monitored, the pressure of the resin layer is increased when the measured value reaches the maximum value at which the resin layer has the minimum viscosity, and the heating means and Controlling the pressurizing means Coil insulating layer curing apparatus characterized.