JP4735370B2 - Varnish impregnation method - Google Patents

Description

  The present invention relates to a varnish impregnation method in which a winding coil inserted and disposed in a stator core is dropped and impregnated with varnish.

For example, in a motor stator used in a vehicle or the like, a varnish is dropped on a winding coil inserted and disposed in a slot of a stator core so that the electric insulation, vibration resistance, oil resistance, Improved chemical properties and heat dissipation.
For example, in the method of dripping and impregnating a varnish disclosed in Patent Document 1, a stator core having a winding coil inserted therein is held so that its axial direction is a horizontal direction. And while rotating this stator core, varnish is dripped at the coil end part which a part of winding coil protrudes from the axial direction edge part of a stator core.
As a result, the varnish dripped onto the coil end portion is permeated into the inside of the winding coil inserted and disposed in the slot of the stator core by a capillary phenomenon, and the entire winding coil is impregnated with the varnish.

JP 2003-189523 A

  By the way, the winding coil inserted and arranged in the stator core is in a state in which residual stress is generated in the coating of each covered electric wire (electric wire coating resin) through the coil forming process and the like so far. In addition, a certain amount of moisture is contained in the slot insulating paper and the wedge inserted into the slots of the stator core. It is known that when the varnish is impregnated with these residual stress and moisture remaining, it is disadvantageous for durability and the like. Therefore, before the varnish dripping step is performed, a preheating step is performed in which the stator core provided with the winding coil is heated to anneal the wire coating resin and remove moisture.

  However, the conventional preheating step is usually performed using a hot-air circulating furnace, but it takes a relatively long time to sufficiently remove residual stress and moisture. Therefore, there has been a demand for rationalization of the preheating process, that is, shortening of the heating time and improvement of water removal efficiency.

  The present invention has been made in view of such conventional problems, and includes a pre-drying step that can shorten the heating time and is excellent in moisture removal efficiency, and can finally obtain a high-quality motor. Is to provide a method.

The present invention heats a winding coil inserted and disposed in a stator core, and performs a pre-drying step for removing residual stress and removing moisture from the wire coating resin in the winding coil;
A cooling step of lowering the temperature of the wound coil heated in the preliminary drying step to a dropping temperature of the varnish;
A dropping step of dropping the varnish on the winding coil ;
A heating and curing step of curing the varnish that has penetrated the wound coil after the dropping step ;
In the preliminary drying step, the stator core is disposed in a reduced-pressure atmosphere, and the winding coil is heated by directly applying high-frequency power to the winding coil ,
In performing the heat curing step, the varnish impregnation method is characterized in that the winding coil is heated by directly applying high-frequency power to the winding coil .

  In the preliminary drying step of the varnish impregnation method of the present invention, the stator core provided with the winding coil is not simply heated, but the stator core is disposed in a reduced pressure atmosphere and heated. Thereby, compared with the case where it heats at normal temperature, the boiling point of a water | moisture content becomes low, and the removal efficiency of a water | moisture content can be improved significantly.

  The winding coil is heated by directly applying high-frequency power to the winding coil. This direct application of the high-frequency power can be heated earlier than in the past due to a combination of self-heating of the winding coils and induction heating of the stator core by the magnetic field generated from the winding coils. Therefore, removal of moisture by heating and removal of residual stress of the wire coating resin can be performed more efficiently than before.

  As described above, in the present invention, the above-described special preliminary drying step can shorten the heating time as compared with the conventional case, and can also improve the water removal efficiency. Therefore, a high quality motor can be finally obtained by carrying out the varnish impregnation method including this preliminary drying step.

  In the present invention, the reduced pressure atmosphere in the preliminary drying step is preferably a reduced pressure state of 10 kPa or less. The reduced pressure atmosphere in the preliminary drying step is effective as long as the pressure is reduced to a little lower than normal pressure. However, the boiling point of water can be reduced to 50 ° C. or lower by setting the reduced pressure state to 10 kPa or lower. The decompression effect can be very high. The reduced pressure state is preferably as the pressure is lower (the higher the degree of vacuum is) within the range allowed by the equipment cost.

Moreover, it is preferable that the heating temperature of the said winding coil in the said preliminary drying process shall be the temperature below the melting point below the glass transition temperature of the said electric wire coating resin . In the preliminary drying step, not only moisture removal but also annealing for removing residual stress of the wire coating resin is aimed. For this reason, in order to obtain this annealing action more effectively, it is preferable to set the heating temperature of the winding coil to a temperature not lower than the glass transition temperature and not higher than the melting point of the wire coating resin as described above.

  Moreover, in this invention, after performing the said preliminary drying process, the said dripping process is performed after performing the cooling process which lowers the temperature of the said heated coil winding to the dripping temperature of a varnish. Here, the dripping temperature of the varnish is a temperature that is lower than the curing temperature of the varnish and sufficiently obtains the fluidity of the varnish, and is determined by the kind of the varnish.

  Moreover, it is preferable to perform the said dripping process performed through the said cooling process, rotating a stator core centering on the central axis. Thereby, when dripping a varnish to the coil end part which protruded from the stator core, a varnish can be uniformly supplied to the circumferential direction. Moreover, after continuing varnish dripping for a predetermined period, in order to infiltrate, the cycle which stops varnish dripping may be repeated several times.

Further, after the dropping step, heat curing step of curing the varnish penetrates into the winding coil. At this time, the winding coil is heated by directly applying high-frequency power to the winding coil . Thereby , it is possible to carry out from the preliminary drying step to the heat curing step in one apparatus without moving the stator core, and the manufacturing method can be rationalized.

Below, the varnish impregnation method concerning the Example of this invention is demonstrated using drawing.
Example 1
First, the varnish containing apparatus 1 for performing the varnish impregnation method of this example is demonstrated.
As shown in FIGS. 1 and 4, the varnish impregnation apparatus 1 of this example includes a rotating means 2 that holds and rotates the stator core 91.
The rotating means 2 includes a rotating motor 21, a rotating main shaft 22 connected to the output shaft of the rotating motor 21, a chuck portion 3 movably disposed on the rotating main shaft 22, and a stator core 91 by the rotating means 2. It has a twist preventing mechanism 24 that prevents the current-carrying cable 41 in the current-carrying means 4 from being twisted when rotating.

  The rotation main shaft 22 is disposed in the horizontal direction, and the chuck portion 3 is constituted by a plurality of claw portions 31 that can protrude radially outward with respect to the rotation main shaft 22. In this example, the six core portions 31 are configured to hold the stator core 91 by pressing six positions on the inner peripheral side of the stator core 91.

The rotary motor 21 is configured to reciprocate the rotary main shaft 22 at a predetermined rotation angle. The torsion prevention mechanism 24 is configured by using a cable bear (registered trademark) that holds the energization cable 41 and can be rotated by the rotation of the rotary main shaft 22.
When the rotary motor 21 is configured to continuously rotate the rotary spindle 22 in one direction, the twist prevention mechanism 24 is configured using a slip ring instead of using a cable bear (registered trademark). Can do. The slip ring is disposed in the middle of the energization cable 41, electrically connects one side and the other side of the energization cable 41, and by a plurality of connection ring portions formed around the central axis of the rotation main shaft 22. It can be rotated with electrical connection.

  As shown in FIG. 1, the varnish impregnation apparatus 1 includes an energizing means for heating the winding coil 92 by directly applying high-frequency power to the winding coil 92 while holding the stator core 91 on the rotating means 2. 4. The energization means 4 includes a connection jig 8 that performs electrical connection between an energization cable terminal formed at the end of the energization cable 41 and a lead wire terminal formed at the end of the lead wire in the winding coil 92. Yes. The connection jig 8 includes a cable side jig portion 81 to which an energizing cable terminal is attached and a lead wire side jig portion 82 to which a lead wire terminal is attached. The cable side jig portion 81 and the lead wire side jig are attached. The part 82 is configured to be detachable from each other.

  The energization means 4 includes a high-frequency power supply device 40 that generates a three-phase high-frequency current. The high-frequency power supply device 40 includes a three-phase high-frequency current that is inserted and disposed in a stator core 91. The winding coil 92 is energized. In addition, the energization cable terminal is crimped to the distal end portion of the energization cable 41 through which a current for energization from the high frequency power supply device 40 flows.

Moreover, the high frequency power supply device 40 can form a high frequency current by increasing the frequency of a commercial three-phase AC power supply using an inverter or the like.
The energization means 4 energizes the winding coil 92 in the stator 9 to cause the winding coil 92 to self-heat due to its electric resistance, and to generate an eddy current in the stator core 91 due to the generation of a magnetic field by energization. By induction heating 91, the stator 9 can be heated to a temperature suitable for each processing step.

Further, as shown in FIG. 1, the varnish dripping means 5 of this example includes a storage tank (not shown) for storing the varnish, a pump 55 (FIG. 7) for feeding the varnish from the storage tank, and a discharge from the pump. It has a liquid feed pipe connected to the outlet, a varnish dropping nozzle 51 connected to the tip of the liquid feed pipe, and a valve (not shown) disposed in the liquid feed pipe.
The varnish dropping nozzles 51 are provided at a plurality of locations so that the varnish can be uniformly dropped onto the coil end portion 922 of the winding coil 92.

Specifically, as shown in FIGS. 1 and 2, a varnish dropping nozzle 51a for dropping varnish on the outer peripheral surface of a coil end portion 922 located on the back side is provided on the back side of the decompression tank 6 described later. Three varnish dripping nozzles 51b for dripping varnish are disposed on the inner peripheral surface of the coil end portion 922 located on the back side in such a manner as to protrude from the rotary main shaft 22 while being disposed three above 91. Yes.
As shown in FIGS. 1 and 3, a varnish dropping nozzle 51 c for dropping varnish on the outer peripheral surface of the coil end portion 922 located on the opening side is provided above the stator core 91 on the opening side of the decompression tank 6. And three varnish dropping nozzles 51d for dropping the varnish on the inner peripheral surface of the coil end portion 922 located on the opening side are located in the coil end portion 922. Yes. Actually, these varnish dripping nozzles 51c and 51d are fixed to an opening / closing door 66 of the decompression tank 6 described later.

Further, as shown in FIGS. 1 and 4, the varnish impregnation apparatus 1 includes a decompression tank 6 provided so as to incorporate at least the rotating means 2 and the varnish dropping means 5, and a decompression pump 71 for decompressing the decompression tank 6. And have.
The decompression tank 6 is formed with an air supply port 62 for supplying air into the decompression tank 6 and a suction port 61 to which a decompression pump 71 is connected. An air blower 72 that supplies air into the decompression tank 6 is connected to the air supply port 62.

  As shown in FIG. 1, the decompression tank 6 includes a container main body 65 and an open / close door 66 that can be opened and closed with respect to the container main body 65. The decompression tank 6 is provided with an exhaust deodorization device 73 that exhausts the solvent and the like in the varnish that evaporates when the varnish is heated from the exhaust port 63, and a gas concentration detector that detects the concentration of the evaporated solvent and the like. It is installed. The control means 10 is configured to monitor the concentration of the solvent or the like detected by the gas concentration detector 731 and control the heating amount by the energization means 4.

Further, as shown in FIG. 1, the rotating means 2, the energizing means 4, the varnish dropping means 5, the decompression pump 71 and the air blower 72 are electrically connected to the control means 10 and controlled by the control means 10. It is configured.
That is, the control means 10 includes a timing at which the rotating means 2 rotates the stator core 91, a timing at which the winding coil 92 is energized by the energizing means 4, and a timing at which the varnish is dropped onto the winding coil 92 by the varnish dropping means 5. The timing for depressurizing the decompression tank 6 by the decompression pump 71, the timing for supplying air into the decompression tank 6 by the air blower 72, and the like can be controlled.

The stator core 91 is embedded with a temperature detector (not shown) such as a thermistor. By detecting the temperature of the stator core 91 using this temperature detector, it is possible to monitor the temperature of the three-phase motor configured using the stator 9.
The connection jig 8 connects only the energizing cable terminal and the lead wire terminal. However, in order to detect the temperature of the stator 9 when the varnish is impregnated, the temperature detection line terminal in the temperature detector is used. Can be connected to an input line terminal in the control means 10.
In this case, the control means 10 monitors the temperature of the stator core 91 detected by the temperature detector, and controls the energization means 4 so that the temperature of the stator core 91 becomes a temperature suitable for performing each process. can do.

As shown in FIG. 5, the varnish impregnation method of this example using the varnish impregnation apparatus 1 having such a configuration is as shown in FIG. 5, a workpiece attaching step S1, a preliminary drying step S2, a first cooling step S3, a dropping step S4, and a heat curing step S5. The second cooling step S6 and the workpiece removal step S7 are sequentially performed.
First, as shown in FIG. 1, the workpiece attachment step S <b> 1 is performed by holding a stator core 91 having a winding coil 92 inserted and disposed on the chuck portion 3 of the rotating means 2 in the decompression tank 6.

  Next, the winding coil 92 inserted and disposed in the stator core 91 is heated to perform a pre-drying step S <b> 2 for removing residual stress and moisture from the wire coating resin in the winding coil 92. In this example, the stator core 91 is disposed in a reduced-pressure atmosphere, and high-frequency power is directly applied to the winding coil 92 to heat the winding coil 92.

  More specifically, the decompression pump 71 described above is operated to decompress the decompression tank 6. While performing this decompression process, high-frequency power is directly applied to the winding coil 92 using the energizing means 4. Thereby, the winding coil 92 can be heated in a reduced pressure state. In this example, the pressure was reduced until the pressure became 10 kPa or less, and the temperature of the winding coil 92 was heated to 180 ° C.

  Next, the first cooling step S3 is performed. In this step, cooling air is introduced from the air supply port 62 while the stator core 91 is held and rotated by the chuck portion 3 of the rotating means 2 until the varnish dropping temperature reaches approximately 80 to 110 ° C. Cooling. In addition, varnish dripping temperature is below the temperature at which the catalyst (peroxide) in a varnish starts reaction. At this time, the exhaust deodorizing device 73 is also operated to achieve a smooth air flow while exhausting from the decompression tank 6.

  Next, a varnish dropping step S4 is performed. In this step, the varnish dropping means 5 drops the varnish while holding and rotating the stator core 91 on the chuck portion 3 of the rotating means 2. At this time, the dropped varnish penetrates from the coil end portion 922 toward the insertion arrangement portion 921 of the winding coil 92 by capillary action. At this time, by detecting the coil temperature so that the coil temperature does not decrease by dripping varnish at room temperature, and performing temperature control so that the coil temperature is optimally maintained for dripping, the capillary phenomenon is more effective. Is going to.

  Next, a heat curing step S5 is performed. Also in this step, the winding coil 92 and the stator core 91 are heated using the above-described energizing means 4 while the stator core 91 is attached to the chuck 3. First, a curing reaction is started by raising the temperature of the catalyst in the dropped varnish to a temperature at which the reaction starts (120 ° C.). Thereby, varnish viscosity becomes high and fluidity | liquidity is eliminated (gelation). Thereafter, the coil temperature is further increased (165 ° C.) to completely cure the varnish. Further, in this step, a large amount of the solvent component of the varnish evaporates, so the exhaust deodorization device 73 is operated. By heating, the varnish gels and hardens, and the wires of the winding coil 92 are fixed.

Next, the second cooling step S6 is performed. In this step, as in the case of the first cooling step S3 described above, cooling air is introduced from the air supply port 62 while holding and rotating the stator core 91 on the chuck portion 3 of the rotating means 2, Cool down to approximately 40 ° C., the temperature that the operator can handle. At this time, the exhaust deodorizing device 73 is also operated to achieve a smooth air flow while exhausting from the decompression tank 6.
Thereafter, the claw portion 31 of the chuck portion 3 is contracted to bring the stator core 91 into a free state, and a workpiece removal step S7 to be removed to the outside is performed.

  As described above, in this example, the series of steps can be performed only by the varnish impregnation apparatus 1. What should be noted here is that, in the preliminary drying step S2, the stator core 91 provided with the winding coil 92 is not simply heated, but the stator core 91 is placed in a reduced-pressure atmosphere and heated. Thereby, compared with the case where it heats at normal temperature, the boiling point of a water | moisture content becomes low, and the removal efficiency of a water | moisture content can be improved significantly.

  The winding coil 92 is heated by directly applying high-frequency power to the winding coil. This direct application of the high-frequency power can be heated earlier than in the past due to a combination of self-heating of the winding coils and induction heating of the stator core by the magnetic field generated from the winding coils. Therefore, the removal of moisture by heating and the removal of residual stress of the wire coating resin can be performed more efficiently than before.

Here, FIG. 6 shows an explanatory diagram of the effect of the reduced pressure when the preliminary drying step S2 is performed. In this figure, the horizontal axis represents time (seconds), the vertical axis represents temperature (° C.) and the degree of vacuum (kPa), and the degree of vacuum A and the boiling point temperature B of water are plotted. For reference, the temperature C in the vacuum tank 6 is also shown. In addition, the unit of the degree of vacuum in the figure is the one in which the normal pressure is 0 kPa and the reduced pressure is represented by-(minus).
As can be seen from the figure, by raising the degree of vacuum to higher than -90 kPa, that is, reducing the pressure to about 10 kPa or less, at least the boiling point of water can be reduced to 50 ° C. or less, and moisture removal by heating. It turns out that an effect can be heightened.

  Moreover, in this example, when performing the heat hardening process S5 which hardens the varnish which osmose | permeated the winding coil 92 after the said dripping process S4, the winding coil 92 is directly supplied by applying high frequency power to the winding coil 92. Heat. As a result, as described above, it is possible to carry out all the steps basically required for the varnish dripping treatment in one varnish impregnation apparatus 1 without moving the stator core 91, thereby streamlining the manufacturing method. be able to.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which shows the principal part structure of the varnish impregnation apparatus in Example 1. FIG. FIG. 3 is an explanatory diagram illustrating an arrangement state of varnish dropping nozzles on the back side of the decompression tank in the first embodiment. FIG. 3 is an explanatory diagram illustrating an arrangement state of varnish dropping nozzles on the opening side of the decompression tank in the first embodiment. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view showing the overall configuration of a varnish impregnation device in Example 1. FIG. 3 is an explanatory view showing a series of steps of varnish impregnation processing in Example 1. FIG. 3 is an explanatory diagram showing the relationship between the degree of vacuum and the boiling point of water in the preliminary drying step in Example 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Varnish impregnation apparatus 2 Rotating means 3 Chuck part 4 Current supply means 5 Varnish dripping means 6 Depressurization tank 71 Decompression pump 72 Air blower 9 Stator 91 Stator core 911 Slot 92 Winding coil 921 Insertion arrangement part 922 Coil end part

Claims (2)

A pre-drying step for heating the winding coil inserted and disposed in the stator core to remove residual stress and moisture from the wire coating resin in the winding coil;
A cooling step of lowering the temperature of the wound coil heated in the preliminary drying step to a dropping temperature of the varnish;
A dropping step of dropping the varnish on the winding coil ;
A heating and curing step of curing the varnish that has penetrated the wound coil after the dropping step ;
In the preliminary drying step, the stator core is disposed in a reduced-pressure atmosphere, and the winding coil is heated by directly applying high-frequency power to the winding coil ,
A varnish impregnation method characterized in that, when performing the heat curing step, the winding coil is heated by directly applying high-frequency power to the winding coil .   2. The varnish impregnation method according to claim 1, wherein the reduced pressure atmosphere in the preliminary drying step is a reduced pressure state of 10 kPa or less.

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