JP5227869B2 - Electric motor - Google Patents

Description

  The present invention relates to an electric motor.

  An electric motor is used as a drive source in various applications, and is often used by being incorporated in various products. For example, it is also used for blowers, compressors for refrigeration and air conditioning, and so-called auxiliary machines such as automobile power windows and wipers. As described above, regarding the electric motor incorporated in the product, not only high efficiency but also miniaturization (thinning) or improvement in assemblability is required. And the shape of the rotor or stator for improving efficiency, downsizing, and improving assemblability has been studied.

  Patent Document 6, Patent Document 7 and Patent Document 8 disclose shapes for improving the assembly of a multiphase claw pole type motor using a dust core. In this example, the magnetic powder is compression-molded to obtain a claw magnetic pole having a complicated shape, thereby improving the efficiency of the motor. That is, by using a complex-shaped core to improve the utilization rate of magnetic flux, the space can be effectively used, and it can contribute to miniaturization and thinning.

JP 2008-289272 A Japanese Patent Laid-Open No. 6-1333489 Japanese Patent Laid-Open No. 11-75337 JP 54-15101 A Japanese Unexamined Patent Publication No. 7-87696 JP 2008-236978 JP 2008-79384 A JP 2008-29142 A

  The dust core is formed by pressing and solidifying magnetic powder, and there are problems regarding strength and dimensional accuracy. As an improvement measure, it is conceivable to resin mold the dust core. By molding the dust core, damage to the dust core can be prevented, and the dimension reference surface can be formed by a resin mold. In this resin-molded motor, the core is covered with an insulating resin, so that the core is in an electrically floating state. For this reason, especially when the load has no contact other than air, such as a fan motor, the rotor, which is a rotating part, becomes a high potential by PWM driving or the like, and there is a risk of electric corrosion of the bearing. At this time, the core must be grounded.

  Patent Document 1 discloses a configuration in which metal brackets are provided on both sides of a three-phase stator core, and the stator (core) and the bracket are connected by conductive pins.

  Patent Document 2 discloses that a motor flange and a metal plate (corresponding to a bracket) and a core are electrically connected to both sides of a stator by a conductive pin, and that the conductive pin uses conductive rubber.

  Patent Document 3 discloses that a conductive rubber, a ring-shaped wave washer, or a coil spring is used as the ground member for the stator core and the bracket.

  Patent Document 4 discloses a method of electrically connecting a stator core and a non-charged metal portion other than the core using a coil spring or a metal tube having a preload equivalent to that of the spring.

  Patent Document 5 discloses a method of connecting a stator core and a printed circuit board having a ground pattern with a tapping screw.

  In Patent Document 1, Patent Document 2, and Patent Document 5, when using a conduction pin or a tapping screw, a hole is provided in advance in the core, and an accurate mounting position is required. Moreover, since the conductive rubber in Patent Document 2 and Patent Document 3 cannot maintain a sufficient preload due to deformation at high temperatures or due to long-term use, there may be problems such as causing poor contact.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a small and thin electric motor while improving productivity and increasing efficiency.

In order to achieve the above object, the present invention adopts the configurations described in the claims .

  According to the present invention, it is possible to provide a small and thin electric motor while improving productivity and increasing efficiency.

Motor cross section Motor exploded view Stator core exploded view Shape of conductive elastic body Stator top view, perspective view Exploded view of single-phase stator Schematic structure diagram of equipment FFU

  In the embodiment of the present invention, a conductive spring-like member is placed on the core surface appearing on the end face of the stator portion with respect to the conductive brackets assembled on the load side and the anti-load side of the stator, thereby reducing the potential of the core. It is characterized by having the same potential as the conductive bracket. The conductive spring-like member functions as a ground member, and uses an elastic body to make reliable contact with the stator core and the bracket.

  As the conductive elastic body, a material known as a part that provides a shielding effect against a gap of a door that can be opened and closed in a housing part such as a control panel is suitable. For example, when the one having the shape shown in FIG. 4 is used, the attachment position is attachment to a flat surface, and it may be attached to a place where there is no hindrance to operation, and accurate positioning is not required.

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

  FIG. 1 is a cross-sectional view of the motor of this embodiment, and FIG. 2 is an exploded view of the motor of this embodiment. The motor according to the present embodiment is configured such that a rotor 22 is arranged at the center of a cylindrical stator 14, sandwiched between upper and lower brackets 13 and 15, and both brackets are coupled by a conductive fixture 21 such as a screw. Yes. A rotation shaft 23 that outputs a rotational force is fixed to the rotor 22, and the rotation shaft 23 is rotatably held by a bearing 16 provided on the brackets 13 and 15, so that the rotor 22 is attached. Yes.

  The rotor 22 includes a magnet 12 in the rotor core 17. In the rotor core 17 of the present embodiment, the magnet 12 is disposed so as to face the inner peripheral surface of the stator 14, and the rotor 22 rotates with the rotating magnetic field from the coil wound around the stator 14, and the rotating shaft 23. Rotational force is output to the outside via.

  The bracket of the present embodiment uses a conductive member, and the two brackets are fixed to each other by the conductive fixture 21 so that both brackets have the same potential. The material of the conductive fixture 21 is not limited, but a metal is desirable to make both brackets have the same potential and to ensure strength. These brackets are not in contact with the stator core, and are coupled to the stator core via a resin mold 18 as will be described later.

  In the above configuration, the conductive fixture 21 functions as a conductive member between the brackets. Therefore, even if both brackets are not in contact with each other, the conductive fixture 21 comes into contact with the brackets 13 and 15 so that both brackets have the same potential. In addition, when adopting a method in which both brackets are fixed in contact with each other, it is not always necessary to use a conductive fixture, but it is necessary to appropriately select the material of the fixture in consideration of strength and the like. .

  The stator 14 is configured by stacking three single-phase stators each having a coil wound thereon (see FIG. 3) and fixing them with a resin mold 18 in a state where three layers are stacked. As the three layers are stacked, a three-phase current having a phase difference of 120 ° in electrical angle flows through each coil. In order to guide the coil held by each single-phase stator to the outside, a coil drawing portion 18 a is formed in the resin mold 18. Further, the single-phase stators holding the three-phase coils are brought into contact with each other to be conducted by being overlapped. With these configurations, the periphery of the stator core and the coil is held in a state of being insulated from the outside by a resin mold 18 made of an insulator or a space.

  Further, the upper surface of the core is exposed on the surface of the stator 14 formed by laminating the single-phase stators, and the conductive elastic body 11 is disposed here. The conductive elastic body 11 is located in a gap between the surface of the stator 14 and the bracket 13 and is in contact with both of them. Although the arrangement of the conductive elastic body 11 will be described later, since the stator 14 and the bracket 13 are electrically connected by the conductive elastic body 11, the conductive elastic body 11 functions as a ground member for the stator 14. The operation of the conductive elastic body 11 will be described.

  As described above, the motor according to the present embodiment has a structure in which a coil is provided inside the resin mold 18 or spaced apart, thereby achieving insulation from the surroundings. However, the rotor 22 disposed in the vicinity of the stator generates a shaft voltage due to the harmonic current of the PWM inverter, which is now mainstream, and the electric corrosion is likely to occur in the bearing 16 that holds the rotating shaft 23. There is a problem. Therefore, it is necessary to take measures against electrolytic corrosion such as using a ceramic material for the bearing 16, and high reliability can be obtained, but this leads to high cost.

  In this embodiment, the stator cores of the respective phases constituting the stator 14 are electrically connected to each other, and are provided with the conductive elastic body 11 as a ground member that makes the stator 14 and the bracket 13 have the same potential. Electric corrosion can be effectively suppressed.

  The conductive elastic body 11 functions as a ground member when attached to one side (for example, the upper bracket 13 side) of the stator core. Therefore, it is not necessarily provided on both sides of the stator 14, but may be provided on both sides (for example, both sides on the upper bracket 13 side and the lower bracket 15 side) for more reliable grounding. At this time, since both sides of the stator 14 are held by the elastic member, it is also suitable for noise and vibration countermeasures.

  Moreover, since the conductive elastic body 11 should just be provided between both the stator 14 and the bracket 13 as mentioned above, the fixing method is not ask | required. For example, if the stator core 51 exposed on the surface of the stator 14 at the time of motor assembly is attached with an adhesive tape and brought into contact with the bracket 13 with a preload, reliable conduction is possible without causing contact problems. . The shape and attachment position of the conductive elastic body 11 suitable for this will be described.

  FIG. 4 is a shape diagram of the conductive elastic body 11 of this embodiment, and shows a state when there is no load. The conductive elastic body 11 is usually made of a copper alloy having a spring property (phosphor bronze or the like). As an example of attachment, an adhesive tape is used for the attachment surface, and it is adhesively fixed to the flat portion of the stator core or the conductive bracket. Adhesive tape may have conductivity, but if it is not conductive, in order to ensure conduction on the adhesive surface side, the tape is not affixed to the entire surface of the adhesive surface, but the metal parts are exposed on both sides of the tape. . When the curved opposing side is pressed when the bracket is assembled, the metal portions on both sides of the tape are also pressed, and the metal portions are in contact with the adhesion-side member.

In FIG. 4, the length in the expansion / contraction direction when the load of the conductive elastic body 11 is not applied is L ₁ , the length in the longitudinal direction is L ₂ , and the length in the short direction is L ₃ . When assembled to the bracket, to be held in a contracted state in the stretch direction, the length of the expansion and contraction direction is smaller than L _1.

  Next, the attachment position of the conductive elastic body 11 will be described together with the shape of the stator core. FIG. 5 is a top view and a perspective view of the stator, and FIG. 6 is an exploded view of the single-phase stator. In the stator of this embodiment, three single-phase stators are overlapped, and this is covered with a resin mold 18 on the side surface and part of the upper and lower surfaces. A plurality of protrusions 41 are formed in the circumferential direction on the upper and lower surfaces where the stator core is exposed. From the coil lead-out portion 18a of the resin mold 18, a conducting wire for flowing a three-phase current is drawn out. The conductive elastic body 11 is attached to the exposed surface of the stator core by pasting or the like.

  As shown in FIG. 6, the single-phase stator is configured by stacking two stator core materials 51 facing each other so as to sandwich the bobbin 53. The stator core material 51 is a molded body having an annular base 51a and a plurality of teeth 51b that protrude from the base 51a and are formed in the circumferential direction. The stator core 51 is formed by compressing magnetic powder.

  A coil 52 is wound around the bobbin 53. In the stator core material 51, the teeth 51b protrude from the base 51a whose surface is planar to the inner peripheral side, and a plurality of teeth 51b are provided in the circumferential direction, and a concave shape is formed between these teeth 51b. 51c is formed. The teeth 51b of the other stator core material 51 are positioned between the teeth 51b of one stator core material 51, and the stator inner peripheral surface is a single phase so that both teeth 51b are arranged with each other. A stator is formed. Further, the bobbin 53 is assumed to be uneven according to the shape of the stator core material 51.

  As described above, the stator core material 51 is made of a powder magnetic core and pressed into the shape shown in the figure by pressing the magnetic powder. Therefore, it is difficult to ensure sufficient flatness on the surface of the base 51a, and individual differences during mass production often occur. For this reason, the surface of a stator core cannot be made into a standard position at the time of bracket attachment. Therefore, in this embodiment, the protruding portion (the outer peripheral upper end portion 18b or the protruding portion 41 of the resin mold 18) is used as the reference surface.

  The outer peripheral upper end 18b and the protrusion 41 will be briefly described. The outer peripheral upper end 18b is a part of the resin mold 18 that covers the stator. Since the resin mold 18 covers the edge portion of the outer peripheral edge of the annular stator, the upper end protrudes from the surface of the stator core. Moreover, the protrusion 41 is provided to cover the core edge portion of the concave 51c with resin during molding, and thus a plurality of protrusions 41 protruding from the surface of the stator core are formed in the circumferential direction. Since these can perform dimensional control at the time of molding, they are suitable as positioning references compared to the surface of the base 51a of the stator core material 51, which is a compact of a dust core.

  FIG. 5 shows an example of the attachment position when the conductive elastic body 11 is attached to the stator. As described above, the conductive elastic body 11 is attached to the stator core or the bracket with an adhesive tape or the like. Even if the positional deviation occurs due to weakening of the adhesive force, the inconvenience due to the positional deviation is avoided by setting the dimensions so as not to protrude from between the adjacent protrusions 41 and contact the rotor. . In particular, if the conductive elastic body 11 is mounted on the outer peripheral side with respect to the protrusion 41, it can be mounted without an adhesive tape.

Specifically, as shown in FIG. 5, when the dimension L ₅ dimension between protruding portions 41 adjacent L _4, from the outer end portion of the protruding portion 41 to the outer peripheral upper end portion 18b of the resin mold 18,
(1) L ₂ > L ₄
(2) L ₃ <L ₅
The dimensional relationship is as follows. At this time, even if there is no adhesive tape as a fixing method, the conductive elastic body 11 does not fall, which contributes to improvement in productivity and reliability.

Conductive elastic body 11, for contact with the improvement of the stator core and the bracket, stretch dimension L ₁ is made larger than the gap dimension between both when the stator core and the bracket is fixed. In the present embodiment, L ₁ is larger than the higher dimension of “the height of the upper end of the protrusion 41 from the stator core surface” or “the height from the stator core surface to the outer peripheral upper end 18 b”. I have to.

  In the above example, since the ground member is an elastic body, precise positioning is not required. Therefore, the structure is simplified, the motor can be assembled without requiring skill, and the cost of the members can be reduced. Therefore, an inexpensive and highly productive motor can be provided.

  In addition, since the elastic body is used, the ground connection is ensured even if the motor is configured by a combination of materials having different thermal expansion coefficients. Further, by devising the spring multiplier and mounting position of this elastic body, it is possible to bring about an effect of suppressing the vibration of the bracket.

  FIG. 7 is a diagram showing an example using the motor 61 shown in the above-described embodiment. In this example, a fan filter unit (FFU) is shown. A fan 63 is attached to the rotating shaft of the motor 61 and is housed in a housing 62 together with a filter 64 to constitute an FFU. The housing 62 has an opening on the upper side, and air is taken in from the opening as the fan 63 rotates. That is, the air is sucked in from the upper part in the figure by the rotation of the fan 63 and passes through the filter 64 attached below the fan 63.

  Therefore, when passing through the filter 64, the air is filtered and discharged to the downstream side (lower part in the figure) of the filter 64 as clean air. During operation of the FFU, it is possible to keep supplying clean air in the clean room by continuously supplying air from which dust and the like have been removed.

  Since the FFU of this embodiment is attached to a clean room ceiling or a semiconductor manufacturing apparatus, there is a strong demand for thinning. Since the filter 64, the motor 61, and the fan 63 are attached to the housing 62, the FFU can be reduced in thickness by reducing the size of the motor 61.

  DESCRIPTION OF SYMBOLS 11 ... Conductive elastic body, 12 ... Magnet, 13 ... Bracket, 14 ... Stator, 15 ... Bracket, 16 ... Bearing, 17 ... Rotor core, 18 ... Resin Mold, 21 ... Fixing tool, 22 ... Rotor, 23 ... Rotating shaft, 41 ... Projection, 51 ... Stator core material, 52 ... Coil, 53 ... Bobbin, 61 ..Motor, 62... Casing, 63... Fan, 64.

Claims (5)

A molded body having an annular base portion and a plurality of teeth portions protruding from the base portion in the circumferential direction is formed by compressing magnetic powder, and three single-phase stators arranged to face each other are formed. A stator formed by laminating phases; and
A resin mold that covers a part of the base and an edge portion of the core of the stator and has a protruding portion protruding from the surface of the base;
A conductive bracket covering the stator,
A rotor that rotates by a rotating magnetic field from the stator, a rotating shaft that rotates as the rotor rotates, and a bearing that holds the rotating shaft;
A grounding member for conducting the stator and the bracket ;
The ground member is a conductive elastic body, and the conductive elastic body is attached to a gap between the base and the bracket,
The stretchable direction length L ₁ at the time of no load of the conductive elastic body is longer than the gap,
The projecting shape portion comprises an outer peripheral upper end portion covering an edge of an outer peripheral edge of the stator core, and a plurality of projection portions covering a concave edge between the teeth,
The longitudinal length L ₂ of the conductive elastic body, is greater than the distance dimension L ₄ of the plurality of the protrusions, the conductive short direction length L ₃ of the elastic body, the outer periphery and the protrusions motor, which is a smaller than the interval dimension L ₅ and the upper end portion. A molded body having an annular base portion and a plurality of teeth portions protruding from the base portion in the circumferential direction is formed by compressing magnetic powder, and three single-phase stators arranged to face each other are formed. A stator formed by laminating phases; and
A resin mold that covers a part of the base and an edge portion of the core of the stator and has a protruding portion protruding from the surface of the base;
A conductive bracket covering the stator,
A rotor that rotates by a rotating magnetic field from the stator, a rotating shaft that rotates as the rotor rotates, and a bearing that holds the rotating shaft;
A grounding member for conducting the stator and the bracket;
The ground member is a conductive elastic body, and the conductive elastic body is attached to a gap between the base and the bracket,
The stretchable direction length L ₁ at the time of no load of the conductive elastic body is longer than the protrusion-shaped part height,
The projecting shape portion comprises an outer peripheral upper end portion covering an edge of an outer peripheral edge of the stator core, and a plurality of projection portions covering a concave edge between the teeth,
The longitudinal length L ₂ of the conductive elastic body, is greater than the distance dimension L ₄ of the plurality of the protrusions, the conductive short direction length L ₃ of the elastic body, the outer periphery and the protrusions motor, which is a smaller than the interval dimension L ₅ and the upper end portion. The electric motor according to claim 1, wherein the conductive elastic body is disposed on both sides of the stator . The bracket includes a first bracket that covers the stator from one side, and a first bracket that covers the stator from the other side, and the first bracket and the second bracket are The electric motor according to any one of claims 1 to 3, wherein the electric potential is the same . 5. The electric motor according to claim 4, wherein the first bracket and the second bracket are connected by a conductive fixture, and are at the same potential via the conductive fixture . 6.

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