JP4682989B2 - Stator manufacturing method - Google Patents

Description

The present invention relates to the production how the stay data, in particular, in the stator at least the coil end is formed by resin molding, the way of manufacturing the stay data motor function is not impaired even when a crack occurs in the mold body It is related.

  A stator constituting a motor (electric motor) is a stator core formed by laminating steel plates each having an annular yoke, a plurality of teeth projecting radially inward from the yoke, and a slot formed between adjacent teeth. The coil is inserted into the slot and wound between the teeth to complete the stator. Here, the coil winding forms include a concentrated winding method in which a coil is wound for each tooth and a distributed winding method in which a coil is wound over a plurality of teeth.

  Recently, with the spread of hybrid vehicles and electric vehicles, miniaturization and high performance of drive motors have become an important development factor. However, even if the motor is downsized, its rotational performance (torque) can be maintained or In order to improve, it is necessary to apply a large current to the coil, and as a result, the amount of Joule heat increases. It is important that this increased heat generation causes a heat loss of the stator and coil and a decrease in magnetic characteristics, leading to a decrease in motor performance, and further effective heat dissipation from a decrease in performance of the organic insulating material. Therefore, the motors for various electric products having high performance and high heat generation, such as the above-mentioned drive motors for hybrid vehicles and electric vehicles, are downsized and high performance (high rotation performance or high torque performance, In addition, high heat dissipation performance is required in addition to high efficiency performance.

  As a technology for imparting high heat dissipation to a motor, a technology for radiating Joule heat generated in a coil by molding the outer periphery of a stator including a coil end with a resin such as ceramics such as alumina is generally applied. As an example, the servo motor stator disclosed in Patent Document 1 can be cited.

  By providing this resin-molded stator, it is possible to obtain a motor that satisfies all the elements of miniaturization, high performance and high heat dissipation. However, since this resin mold body has low impact resistance and cracks are likely to occur due to thermal expansion and contraction due to the thermal cycle, a part of the resin mold body is peeled off and pulled into the rotor due to the occurrence of this crack. Therefore, there is a high possibility that problems such as locking of the motor and inducing bearing wear on the motor components will occur. In particular, the drive motor for a hybrid vehicle needs to be a motor that can withstand a cooling cycle of −40 ° C. to 150 ° C. or 180 ° C. due to the engine room temperature and use in a cold region. It is necessary to be able to withstand vibration acceleration at a high speed of about 18000 rpm. Therefore, measures for preventing cracks in the resin mold body have been an urgent issue.

JP 2004-289928 A

The present invention has been made in view of the above-described problems, and relates to a stator having a resin mold body formed on the outer periphery thereof and a motor including the stator, in addition to downsizing, high performance, and high heat dissipation, and to provide a way of manufacturing a stator without impairing the durability of the motor even if a crack occurs in the resin mold body.

  To achieve the above object, a stator according to the present invention includes an annular yoke, a plurality of teeth projecting radially inward from the yoke, and a slot formed between adjacent teeth, and a stator core. And a coil formed around the teeth. A resin mold body is formed on at least an outer peripheral side of the stator and a coil end of the stator, and at least a surface of the resin mold body includes the resin mold body. A protective layer made of a resin material having relatively high crack resistance as compared with the above is formed.

  The stator of the present invention may have either a form in which the coils are concentratedly wound or a form in which the coils are wound in a distributed manner. However, even when the heat generation amount is larger and a resin mold body is formed on the outer periphery of the stator, the stator It is particularly suitable for a concentrated winding type stator that does not become too large. In the concentrated winding method, the coil bobbin on which the coil is formed may be fitted to the teeth, or the conductive wire may be wound directly on the outer periphery of the teeth. Further, the stator core constituting the stator may be a laminated body in which silicon steel plates are laminated, or from a powder magnetic core in which magnetic powder formed by coating a soft magnetic metal powder with an insulating binder is pressed. It may be molded.

  The resin molded directly on the outer periphery of the stator has a filling property between coil conductors of about 10 μm, and an appropriate resin material having a heat dissipation performance is used. A possible unsaturated polyester resin (BMC) is preferred.

  In the stator of the present invention, at least the outer peripheral side surface of the stator core in which the coil is formed around the teeth and the coil ends at both ends thereof are covered with a molded body made of resin, and the molded body is protected by a separate resin. Covered with a layer.

  This protective layer may be configured to surround only the outer periphery (outer peripheral side surface and coil end portion) of the molded body, or may be configured to cover the side surface facing the rotor on the inner peripheral side of the stator. Good.

  As the resin for forming the protective layer, a material having relatively high crack resistance as compared with the resin mold body (resin for forming) is selected.

  Here, in order to improve crack resistance, a relatively tougher material can be selected as the protective layer resin as compared with the resin mold resin. For example, a film made of polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polyethylene naphthalate (PEN), polyetherimide (PEI), or the like, which is a high heat resistant film, can be used. As an example of a method of forming a protective layer having a predetermined shape with the film, there is a method of shaping by a female die.

  On the other hand, as another measure for improving the crack resistance, a material having a relatively high strength can be selected as the resin for the protective layer as compared with the resin for the resin mold body. For example, a GFRP prepreg or a long fiber glass reinforced mat (SMC) compression molded body can be used.

  For example, when a protective layer is molded from a thermoplastic resin, the above-described resin material for the protective layer is preferably a material having high fluidity. Since the thickness of the molded body can be reduced by high fluidity, thin molding is possible even when the outer periphery of the resin mold body is covered with a protective layer made of resin, and further, from the resin mold body to the outside The heat dissipation performance is not reduced.

  The motor according to the present invention includes at least the stator and a rotor disposed therein.

  A small motor is obtained by providing the stator described above, that is, a stator having a stator core in which the outer peripheral side of the stator core and the coil end are covered with a resin mold body, and a protective layer having a relatively high crack resistance is provided on the outer periphery. , High performance, high heat dissipation, and a highly durable motor can be obtained. This is because even when a crack occurs in the resin mold body and the mold material is peeled off, the protective material on the outer periphery can prevent the mold material from falling off, so there is no problem in driving the motor. .

  A stator manufacturing method according to the present invention includes a stator core including an annular yoke, a plurality of teeth projecting radially inward from the yoke, and a slot formed between adjacent teeth, A stator formed of a coil, and a resin mold body is formed on at least an outer peripheral side of the stator and a coil end of the stator, and a surface of the resin mold body is compared with the resin mold body. A method of manufacturing a stator in which a protective layer made of a resin material having a relatively high crack resistance is formed, wherein a divided body of the protective layer is disposed on the cavity surfaces of both the movable mold and the fixed mold, A first step in which a protective layer is coated on the coil end by accommodating the stator core formed with the cavity in the cavity, and a second step in which the inside of the cavity is evacuated. , Is characterized in that the resin of the resin molded body is at least provided with a third step of injection-molding, the between the protective layer and the stator core.

  The protective layer constituting the stator is divided into two in the height direction of the stator, and the respective divided bodies are fitted into center posts provided in, for example, a movable type and a fixed type. The center post is formed with an opening communicating with the outside, and a gap is formed between both ends in a posture in which the movable die and the stationary die are closed. For example, a clearance may be provided in a slide hole of an ejector pin for extruding a molded product formed in the movable mold, and the protective layer divided body may be vacuum-sucked through the clearance.

  For example, the inside of the cavity is evacuated from the external vacuum device or the like through the center opening of the center post, and similarly, the resin for the resin mold body is injection-molded between the stator and the protective layer through the center opening of the center post. .

  By opening the mold and cooling as necessary (in BMC with a molding temperature of approximately 150 ° C., the protective layer is stable against heat, so the mold is removed without cooling), and the resin mold body and resin protection A stator coated with layers is formed. It should be noted that the tips of both the movable and fixed center posts are in contact with each other, and a suction hole is formed in a part of the center post so that the suction path communicating with the external vacuum device is centered. It is also possible to evacuate the cavity through the suction hole provided in the post.

  In a preferred embodiment of the stator manufacturing method according to the present invention, in the stator manufacturing method, the stator core is formed with a through-hole extending in the height direction in advance, in the second step. The suction path that communicates with the vacuum device communicates with the through-hole, and the inside of the cavity is evacuated through the interior of the stator core.

  For example, a through hole is formed in a portion of the yoke of the stator core that does not obstruct the magnetic flux flow, a minute hole is formed in the protective layer, and a suction path communicating with the vacuum device is connected to the through hole. The inside of the cavity can be evacuated. According to this method, even if the evacuation in the cavity is not sufficiently performed only by evacuating through the center post, the vacuum level in the cavity can be increased by evacuating between the laminated steel plates. Further, even when the inner peripheral side (side surface facing the rotor) of the stator is covered with a protective layer, the cavity can be evacuated.

  As can be understood from the above description, according to the stator of the present invention and the motor including the stator, the motor can be reduced in size, performance, heat dissipation, and durability. Moreover, according to the stator manufacturing method of the present invention, the stator can be efficiently manufactured, and the manufacturing yield of high-performance stators and motors can be increased.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view showing an embodiment of a stator manufacturing method of the present invention, FIG. 2 is an enlarged perspective view of a stator core on which coils are formed, and FIG. 3 is an embodiment of a stator of the present invention. It is a perspective view of a form. FIG. 4 is a schematic view showing another embodiment of the stator manufacturing method of the present invention, and FIG. 5 is a perspective view of another embodiment of the movable cavity surface. FIG. 6 is a schematic view showing still another embodiment of the stator manufacturing method of the present invention, and FIG. 7 is an enlarged plan view of a part of the stator applied in the manufacturing method of FIG.

  FIG. 1 is an explanatory view for explaining an embodiment of a stator manufacturing method according to the present invention, and FIG. 2 is an enlarged view of a stator core 1. In this manufacturing method, a coil bobbin 2 in which a conductive wire is wound and a coil 3 is formed is fitted to each tooth 11,... Projecting radially from an annular yoke 12 of a stator core 1 formed by laminating silicon steel plates. This is a concentrated winding type.

  The stator core 1 in which the coil is formed is prepared, the detailed structure is omitted, and the protective layer divided body 51 is provided on the center posts 62 and 72 of the cavities 61 and 71 of both the movable mold 6 and the fixed mold 7 shown in the figure. , 52 are attached.

  The protective layer divided bodies 51 and 52 are formed of a film or a molded body that surrounds at least the coil end and the outer peripheral side of the stator core 1. ), A polyetherimide (PEI) or other high heat resistant resin film, and in the case of a molded body, it is a compression molded body of GFRP prepreg or long fiber glass reinforced mat (SMC). Any material is preferably as thin as possible. For example, a protective layer divided body having a thickness of about 0.5 to 1.0 mm is used.

  The stator core 1 is accommodated in the cavities 61 and 71 of both the movable mold 6 and the fixed mold 7, the mold is closed, the cavity is evacuated, and the injection pipe is inserted into, for example, the through hole formed in the center post 72 of the fixed mold 7. By inserting 91 and filling the unsaturated polyester resin (BMC), the BMC is filled between the stator core 1 and the divided parts 51 and 52 of the protective layer. The stator 10 as shown in FIG. 3 is manufactured by extruding the molded product by an appropriate extruding means after opening the mold.

  In FIG. 3, a protective layer 5 in which protective layer divided bodies 51 and 52 are integrated is formed on the outer periphery of the stator core. Between the protective layer 5 and the stator core 1, a resin mold body 4 in which BMC is cured. Is formed.

  According to the stator 10 shown in FIG. 3, the resin mold body 4 excellent in heat dissipation is formed at least on the coil end and the outer peripheral side of the stator core 1, and is thin on the outer side and is crack resistant as compared with the mold body 4. Since the high protective layer 5 is formed, it is possible to effectively prevent the mold pieces from being scattered even after the occurrence of cracks in the resin mold body having low impact resistance. Therefore, the durability is high and the heat dissipation is excellent. A stator can be obtained.

  FIG. 4 is an explanatory view for explaining another embodiment of a stator manufacturing method.

  As shown in the drawing, an ejector device 8 having a large number of ejector pins 81,... Is provided on one side of the movable die 6A, and ejector pin through holes (not shown) are formed in the movable die 6A. The inner diameter of the through hole is formed to be larger than the outer diameter of the ejector pin 81, and the ejector pin 81 is loosely fitted in the through hole so as to be able to advance and retreat. The final molded product can be extruded from the movable mold 6A by pushing the ejector pins 81,.

  The through hole provided in the movable die 6A faces the cavity 61 of the movable die 6A, and the cavity can be evacuated from the gap between the two in a posture in which the ejector pin 81 is loosely fitted in the through hole. ing. Specifically, a pipe line 82 provided in the ejector device 8 communicates with a through-hole provided in the movable mold 6A, and is sucked by a vacuum pump 92 through the pipe line 82 so as to be in the cavity. A vacuum is evacuated.

  In the fixed mold 7A, a gas suction part 71a made of sintered metal is formed in a part of the cavity 71, and the gas suction part 71a and the pipe line 74 are communicated with each other via the pipe line 74. Vacuum suction is performed with a vacuum pump 92.

  By vacuuming from both the movable mold side and the fixed mold side, the divided bodies 51 and 52 of the protective layer are positioned while being vacuum-sucked to both cavity surfaces.

  Further, for example, in the form of a movable cavity shown in FIG. 5, by providing an opening 61a,... In the center post 62, the gap between the ejector pin 81 and the through hole is passed through the opening 61a,. It is also possible to evacuate the cavity.

  After evacuation, the injection conduit 91 is inserted into the cavity through the center opening 73 of the fixed mold 7A, and is filled with BMC.

  FIG. 6 is an explanatory view for explaining still another embodiment of the stator manufacturing method. First, a stator core 1A necessary for the present manufacturing method when this manufacturing method is applied will be described based on a partial plan view of FIG.

  The stator core 1A used in this manufacturing method extends in the height direction of the core near the intersection between the axis of the teeth 11 and the circumferential axis of the yoke, in particular, at a portion where the magnetic flux flow in the yoke 12 is not hindered. The through-hole 13 to be formed is formed.

  A stator core 1A having a plurality of through holes 13,... At predetermined portions of the yoke and having coils formed on teeth is accommodated in the cavities of the movable mold 6B and the fixed mold 7B shown in FIG.

  Here, suction pipes 63,..., 75,... Communicating with an external vacuum pump project from both the cavity of the movable mold 6B and the cavity of the fixed mold 7B, and the tip plugs thereof are through holes of the stator core 1A. 13 is connected to both openings.

  In addition to vacuuming through the center post as described above, the inside of the cavity is brought to a high vacuum level by vacuuming through the through hole 13 formed in the yoke of the stator core 1A as in the present manufacturing method. be able to. Furthermore, since the air in the gap between the steel plates can be effectively vented by directly evacuating the stator core made of laminated steel plates, the stator core itself can be narrowed by increasing the adhesion between the steel plates. It leads to.

  The present inventors manufactured the stator by the manufacturing method shown in the explanatory view of FIG. First, the protective layer was manufactured by stacking three Nittobo glass prepregs: WP-15D, heating a predetermined shape mold to 130 ° C., setting the glass prepreg on this, and compression molding. After 15 minutes, it was taken out from the mold, and a protective layer (divided body) having a thickness of 0.5 mm was obtained. Subsequently, the end surface of this protective layer was trimmed into a predetermined shape to remove burrs.

  The molded protective layer (divided body thereof) was placed on the cavity surfaces of both the movable mold and the fixed mold, and the mold was preheated while preventing the displacement of the protective layer divided body by evacuation.

  Next, a stator core preheated to a predetermined temperature was placed on the outer periphery of the movable center post along the inner diameter thereof, and the mold was closed.

  Next, BMC resin (RNC-833 manufactured by Showa Polymer Co., Ltd.) having a thermal conductivity of 0.7 W / m · K is used as a material for the resin mold body, and thermosetting manufactured by Niigata Machine Techno Co., Ltd. BMC resin was injection-molded between the protective layer and the stator core using an injection molding machine for functional resin. The injection was performed at a mold temperature of 150 ° C., an injection speed of 17 mm / second, and a holding pressure of 5 MPa.

  After completion of the injection, the stator core was placed for 300 seconds in a posture in which it was accommodated in the mold, the resin was thermoset, the mold was opened, and the stator was taken out.

  As a result of disassembling the stator, cutting the resin mold body and checking the filling state, a part of the unfilled portion was found between the protective layer on the movable mold side, but the BMC resin was between the protective layer and the stator core. Was surely filled.

  Next, the stator was manufactured using the movable mold in which the manufacturing method shown in the explanatory diagram of FIG. 4 was applied and the center post on the movable mold side was provided with the opening for vacuuming shown in FIG. In addition, eight openings were provided in the circumferential direction of the center post.

  The specific manufacturing method is the same as in Example 1. As a result of disassembling and cutting the manufactured stator in the same manner as in Example 1 and checking the resin filling state, there was no unfilled portion.

  Next, a thermal cycle test was similarly performed on the stator manufactured by the method of Example 2 and the conventional stator (stator without a protective layer), and the state of cracks on the stator surface before and after the test was verified. In this cooling / heating cycle test, 500 cycles of 3 hours in a high temperature atmosphere of 150 ° C. and then 3 hours in a low temperature atmosphere of −40 ° C. are performed, and the stator is left in this environment.

  When the crack state was verified, no cracks were present on the stator surface (protective layer surface) of Example 2 according to the production method of the present invention.

  On the other hand, in the stator of the conventional structure (comparative example), the mold material did not fall off, but there were seven hair cracks, and the total extension was as long as 130 mm. According to the crack state of this comparative example, it is judged that the possibility of cracks falling off from the stator surface becomes extremely high when the number of thermal cycles is further increased by several tens of cycles. Further, even in the 500 cycle state, it is inevitable that the existing cracks are further extended due to vibration during driving of the motor, and the mold material falls off.

  As is clear from the results of this experiment, by providing a thin protective layer with higher crack resistance than the resin mold body on the outer periphery of the resin mold body, for example, a drive motor for a hybrid vehicle can be experienced. It is possible to reliably prevent the resin mold material from dropping off under a cold cycle environment. In addition, this stator is not disturbed in size reduction, and is a stator excellent in heat dissipation.

  A motor having a stator core manufactured by the manufacturing method described above can be applied not only to next-generation SR motors for hybrid vehicles, but also to all types of motors such as motors used in various home appliances. it can.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

It is the schematic diagram which showed one Embodiment of the manufacturing method of the stator of this invention. It is an expansion perspective view of the stator core in which the coil was formed. It is a perspective view of one embodiment of a stator of the present invention. It is the schematic diagram which showed other embodiment of the manufacturing method of the stator of this invention. It is a perspective view of other embodiment of a movable type cavity surface. It is the schematic diagram which showed further another embodiment of the manufacturing method of the stator of this invention. FIG. 7 is an enlarged plan view of a part of a stator applied in the manufacturing method of FIG. 6.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,1A ... Stator core, 10 ... Stator, 11 ... Teeth, 12 ... Yoke, 13 ... Through-hole, 2 ... Coil bobbin, 3 ... Coil, 4 ... Resin mold body, 5 ... Protective layer, 51, 52 ... Protective layer division body 6, 6A, 6B ... movable type, 61 ... cavity, 62 ... center post, 62a ... through passage, 7, 7A, 7B ... fixed type, 71 ... cavity, 72 ... center post, 8 ... ejector device, 81 ... ejector Pin, 91 ... Pipe for injection, 92 ... Vacuum pump

Claims (1)

A stator including a stator core including an annular yoke, a plurality of teeth projecting radially inward from the yoke, a slot formed between adjacent teeth, and a coil formed around the teeth. A resin mold body is formed at least on the outer peripheral side and the coil end of the stator, and the surface of the resin mold body has a relatively high crack resistance compared to the resin mold body. A stator manufacturing method in which a protective layer of a material is formed,
A first step in which a divided body of the protective layer is disposed on the cavity surface of both the movable mold and the fixed mold, and the stator core on which the coil is formed is accommodated in the cavity to cover the coil end with the protective layer;
A second step of evacuating the cavity;
And at least a third step of injection molding a resin for a resin mold body between the protective layer and the stator core ,
A through hole extending in the height direction is formed in the stator core in advance, and in the second step, a suction path communicating with the vacuum device is communicated with the through hole, and a cavity is formed through the interior of the stator core. The stator is produced by evacuating the inside of the stator.

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