JP2013207959A - Dc brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DC brushless motor capable of securing with certainty a distance between a substrate on which a Hall IC is mounted and a magnet for a sensor, according to a rule.SOLUTION: A DC brushless motor comprises: a rotor 104 arranged freely and rotatably inside a stator 113; a sensor magnet 103 fixed at one end part in a shaft center direction, of the rotor 104; a housing 108 resin-molded by a molding metal mold and covering at least an outer periphery of the stator 113; and a substrate 109 in which a Hall IC 114 opposed to the magnet 103 is mounted on the lower surface, and that is installed on an insulator 107a of the stator 113 in a state that a distance from the magnet 103 is kept constant by the resin used at the molding of the housing 108. The substrate 109 is attached with a substrate supporting part in advance, and when the substrate supporting part is pressed in a vertical direction by upper and lower molds of the molding metal mold, a distance from the magnet 103 is maintained.

Description

  The present invention relates to a DC brushless motor, and more particularly to a technique for ensuring a distance between a Hall IC that detects a rotational position of a rotor and a magnet.

  As a conventional DC brushless motor, a Hall IC is fixed to an L-shaped pressing plate by soldering, etc., and a claw provided on the pressing plate is hooked on a groove processed into a stator and mechanically fixed. There is one in which a substrate on which an IC is fixed by soldering or the like is fixed to a stator using through bolts and nuts (see, for example, Patent Document 1).

JP 2000-197291 A (page 3, FIG. 3)

In the above-described prior art, an L-shaped presser plate is required, the groove portion must be processed in the stator, the substrate must be fixed to the stator using bolts and nuts, and the DC brushless There was a problem that the number of assembly steps of the motor increased.
In the case of an IPM motor (abbreviation for magnet-embedded motor), the distance between the magnetic sensor such as a Hall IC that detects the rotational position of the rotor and the magnet for the sensor is specified. There was a variation due to restrictions.

  The present invention has been made to solve the above-described problems, and reliably secures the distance between the substrate on which the Hall IC is mounted and the magnet for the sensor as specified without increasing the number of assembly steps. An object of the present invention is to provide a DC brushless motor that can be used.

  The DC brushless motor according to the present invention is fixed to a stator that generates a rotating magnetic field, a rotor that is rotatably arranged inside the stator, and rotates at the same cycle as the rotating magnetic field, and one end portion in the axial direction of the rotor, A sensor magnet that rotates together with the rotor, a resin molded by a molding die, a housing that covers at least the outer periphery of the stator, and a Hall IC that faces the magnet are mounted on the lower surface. And a substrate installed on the stator insulator in a state in which the distance between them is kept constant, and the substrate has a substrate support portion attached in advance, and the substrate support portion is formed by an upper mold and a lower mold of the molding die. The distance from the magnet is maintained when the mold is pressed from above and below.

  According to the present invention, when the housing is resin-molded by the molding die, the upper and lower molds of the molding die are used to hold down the substrate support portion attached to the substrate from above and below. As a result, even if the resin for housing molding is injected into the molding die, the substrate is fixed without being inclined by the substrate support portion, and therefore the distance between the lower surface of the substrate and the magnet for the sensor is constant. Thus, variation in the detection performance of the rotational position of the rotor can be minimized. Further, since the substrate is fixed on the insulator by the resin at the time of molding the housing, the man-hour is not increased.

It is a longitudinal cross-sectional view of the DC brushless motor which concerns on embodiment. It is an expansion perspective view which shows the board | substrate before housing molding in the DC brushless motor of FIG. FIG. 3 is an enlarged perspective view showing the substrate of FIG. 2 as viewed from below. It is a side view of the board | substrate upper surface support part shown in FIG. It is a side view of the board | substrate lower surface support part shown in FIG.

  1 is a longitudinal sectional view of a DC brushless motor according to an embodiment, FIG. 2 is an enlarged perspective view showing a substrate before molding a housing in the DC brushless motor of FIG. 1, and FIG. 3 shows the substrate of FIG. 4 is an enlarged perspective view, FIG. 4 is a side view of the substrate upper surface support portion shown in FIG. 3, and FIG. 5 is a side view of the substrate lower surface support portion shown in FIG.

  The DC brushless motor shown in FIG. 1 is an inner rotor type motor. The rotor 104 is integrated by, for example, press-fitting a rotary shaft 102 and is rotatably supported by the upper and lower bearings 101 via the rotary shaft 102. ing. The rotor 104 is disposed with a gap inside the stator 113 as described above, and a plurality of magnets 104a are embedded in the circumferential direction. Further, a magnet holding portion 103 a holding a sensor magnet 103 is fixed to the upper end portion of the rotor 104.

  The above-described stator 113 has a plurality of teeth protruding inward toward the axial center, and a coil 106 is wound around each of the teeth via insulators 107a and 107b provided at the upper and lower ends of the stator 113. It is configured to be turned. Each coil 106 is connected for each phase (for example, U phase, V phase, W phase), and generates a rotating magnetic field by a current from an inverter (not shown) flowing in through the power lead 112. The rotor 104 is rotated at the same cycle as the rotating magnetic field. At this time, the magnet 103 also rotates in the same direction together with the rotor 104.

  The outer periphery of the stator 113, that is, the portion excluding the bearing 101, the rotating shaft 102, the magnet 103, the magnet holding portion 103a, and the rotor 104 is covered with a housing 108 (made of resin) formed by resin molding with a molding die. Yes. By covering the stator 113 with resin, an insulating effect and a waterproof effect can be achieved.

  As shown in FIGS. 1 and 2, the insulator 107 a at the upper end of the stator 113 is provided with, for example, three or more insulator pins 105 for each tooth in the circumferential direction. The insulator pin 105 is integrally formed with the insulator 107a. Further, an insulator pin 105 passes through the insulator 107a at the upper end, and a substrate 109 supported by a substrate upper surface support portion 110 and a substrate lower surface support portion 111 described later is disposed.

  As shown in FIGS. 2 and 3, the board 109 has a connector 115 mounted on the upper surface and three Hall ICs 114 facing the magnet 103 on the lower surface. The substrate 109 is covered and fixed with resin together with the connector 115 and the three Hall ICs 114 when the housing 108 is molded. By covering the substrate 109 with resin when the housing 108 is molded, man-hours can be reduced.

  When the substrate 109 is fixed with resin, a distance A between the lower surface of the substrate 109 and the sensor magnet 103 is secured as shown in FIG. A method of holding the distance A will be described later. With the distance A, the three Hall ICs 114 mounted on the lower surface of the substrate 109 enter the magnetic field of the magnet 103, and the magnetic flux from the magnet 103 can be reliably detected.

  The connector 115 described above is connected to a control circuit (not shown) such as a microcomputer via a control lead wire 116. The Hall IC 114 generates a signal every time the sensor magnet 103 passes and inputs the signal to the control circuit via the connector 115 and the control lead wire 116. On the other hand, the control circuit detects the rotational position of the rotor 104 based on the signals from the three Hall ICs 114. When the rotational position of the rotor 104 is deviated from the rotational magnetic field, the rotor 104 has the same cycle as the rotational magnetic field. An inverter (not shown) is controlled to rotate.

  The substrate 109 has, for example, four or more through holes 109a (see FIG. 3), and as described above, the insulator pins 105 are inserted into the respective through holes 109a and installed on the insulator 107a (see FIG. 2). ). When the substrate 109 is installed on the insulator 107a, the substrate 109 is installed across the teeth of the stator 113 due to the relationship between the number of the insulator pins 105 and the number of the through holes 109a. Further, as described above, the substrate 109 is supported by the substrate upper surface support portion 110 and the substrate lower surface support portion 111 at two locations in the circumferential direction. The substrate upper surface support portion 110 and the substrate lower surface support portion 111 constitute a substrate support portion.

  As shown in FIG. 4, the substrate upper surface support portion 110 is formed in a bottomed cylindrical shape having a hole 110a therein, and the substrate lower surface support portion 111 includes a flat head portion 111a as shown in FIG. It is comprised with the column-shaped insertion part 111b which makes the center of the head 111a an axial center. In addition, the board | substrate upper surface support part 110 and the board | substrate lower surface support part 111 are shape | molded by materials, such as PPS, unsaturated polyester, and PET, for example.

  When the substrate 109 is installed on the insulator 107a, first, the insertion portions 111b of the substrate lower surface support portion 111 are respectively inserted into two through holes (not shown) provided in the substrate 109, and each insertion portion 111b is further inserted. Are inserted into the holes 110a of the substrate upper surface support portion 110, and the substrate 109 is supported by the peripheral edge portion 110b of the substrate upper surface support portion 110 and the head portion 111a of the substrate lower surface support portion 111 (see FIG. 3). In this state, the insulator pin 105 is inserted into each through hole 109a provided in the substrate 109, and the substrate 109 is placed on the insulator 107a (see FIG. 2). At this time, the distance between the lower surface of the substrate 109 and the sensor magnet 103 is A.

  The above-described substrate upper surface support portion 110 and substrate lower surface support portion 111 are fixed from above and below by an upper die and a lower die of the molding die when the housing 108 is resin-molded by a molding die. For this reason, even when resin (liquid) is injected into the molding die at an injection pressure of 8 MPa to 12 MPa, the substrate 109 is connected to the insulator pin 105 by the fixed substrate upper surface support portion 110 and the substrate lower surface support portion 111. The above-mentioned distance A is ensured without deviating from or tilting. In addition, when the housing 108 is resin-molded by the molding die, a liquid resin is injected into the molding die, and the inlet is provided on the insulator 107b side of the lower end portion of the stator 113. . This is to prevent the resin from being directly injected onto the substrate.

  As described above, in the embodiment, when the housing 108 is resin-molded by the molding die, the two substrate support portions attached in advance to the substrate 109 with the upper die and the lower die of the molding die. (Consisting of the substrate upper surface support portion 110 and the substrate lower surface support portion 111) is pressed from above and below. As a result, even if the resin for housing molding is injected into the molding die, the substrate 109 is fixed without being inclined by the substrate support portion, so that the space between the lower surface of the substrate 109 and the sensor magnet 103 is reduced. The distance A can be reliably ensured, and variations in detection performance of the rotational position of the rotor 104 can be minimized.

  Further, since the substrate 109 is fixed on the insulator 107a by the resin at the time of molding the housing 108, the man-hour is not increased. Furthermore, since three or more insulator pins 105 are provided on the insulator 107a for each tooth, the substrate 109 can be positioned easily and arbitrarily.

  In the embodiment, it has been described that the substrate upper surface support portion 110 and the substrate lower surface support portion 111 that are attached to the substrate 109 in advance using the upper mold and the lower mold are pressed from above and below. When pressed by the mold and the lower mold, the cylindrical substrate upper surface support portion 110 may bulge outward. In that case, the thickness is adjusted so that the substrate upper surface support portion 110 bulges outward without being damaged by pressure, and the height is the same as the resin surface (the outer surface of the housing 108) even if the substrate upper surface support portion 110 swells. The substrate upper surface support portion 110 is used in consideration of the height of the height so that the height is increased. As a result, the substrate upper surface support portion 110 is not damaged, and a distance A between the lower surface of the substrate 109 and the sensor magnet 103 can be secured.

  Alternatively, when the substrate upper surface support portion 110 is formed of an elastic member such as hard rubber and is held by the upper die and the lower die, the cylindrical substrate upper surface support portion 110 moves outward. You may make it swell. In that case, similarly to the above, the substrate upper surface support portion 110 is used in consideration of the height so that the height is the same as the resin surface even when the substrate upper surface support portion 110 swells. When the substrate upper surface support portion 110 is made of an elastic member in this way, the substrate upper surface support portion 110 is not damaged by pressure, and therefore a distance A between the lower surface of the substrate 109 and the sensor magnet 103 is secured. can do.

  In the embodiment, the two substrate support portions are attached to the substrate 109. However, the present invention is not limited to this, and three or more substrate support portions may be used.

  In the embodiment, the insulator 107a having the insulator pin 105 is provided at the upper end of the stator 113. However, the insulator 107a may be used for a motor that does not require the substrate 109 having the Hall IC 114. Cost reduction can be realized by making common use.

  100 DC brushless motor, 101 bearing, 102 rotating shaft, 103 magnet for sensor, 103a magnet holder, 104 rotor, 104a magnet, 105 insulator pin, 106 coil, 107a, 107b insulator, 108 housing, 109 substrate, 109a through hole , 110 substrate upper surface support portion, 110a hole, 110b peripheral edge portion, 111 substrate lower surface support portion, 111a head portion, 111b insertion portion, 112 power supply lead wire, 113 stator, 114 Hall IC, 115 connector, 116 control lead wire.

Claims (6)

A stator that generates a rotating magnetic field;
A rotor that is rotatably arranged inside the stator and rotates at the same cycle as the rotating magnetic field;
A sensor magnet fixed to one end of the rotor in the axial direction and rotating together with the rotor;
A housing that is resin-molded by a molding die and covers at least the outer periphery of the stator;
A Hall IC facing the magnet is mounted on the lower surface, and a substrate placed on the insulator of the stator in a state where the distance from the magnet is kept constant by a resin during molding of the housing. ,
The substrate has a substrate support portion attached in advance, and the distance between the substrate and the magnet is maintained when the substrate support portion is pressed from above and below by the upper mold and the lower mold of the molding die. DC brushless motor characterized by the above.   The board is temporarily fixed with a plurality of insulator pins provided in the insulator before resin molding of the housing, and a plurality of board support portions are attached. The DC brushless motor according to 1. The substrate is temporarily fixed with four or more insulator pins passing therethrough,
The DC brushless motor according to claim 2, wherein three or more insulator pins are provided for each tooth of the stator.   The substrate support portion includes a substrate upper surface support portion formed in a bottomed cylindrical shape having a hole therein, a flat head portion, and a columnar insertion portion centering on the center of the head portion. 2. A lower surface support portion, and an insertion portion of the substrate lower surface support portion is inserted from the lower surface of the substrate into the hole of the substrate upper surface support portion, and is attached to the substrate. The DC brushless motor as described in any one of thru | or 3.   5. The DC brushless motor according to claim 4, wherein the thickness of the substrate upper surface support portion is adjusted so as to expand outward when the upper mold and the lower mold are combined. .   The DC brushless motor according to claim 4, wherein the substrate upper surface support portion is formed of an elastic member.

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