JP6177454B2 - Electric motor and exhaust fan - Google Patents

Description

  The present invention relates to an electric motor and a ventilation fan including a stator and a rotor.

  Conventionally, an electric motor is used in which a rotor is disposed inside a stator and a shaft coupled to the rotor is rotated. Patent Document 1 discloses an electric motor including a bearing that rotatably holds a shaft, a bracket that holds the bearing, and a board that is provided on the opposite side of the bearing with the bracket interposed therebetween.

JP 2012-253845 A

  In the electric motor as disclosed in Patent Document 1, a spring may be inserted between the bearing and the bracket in order to apply a load to the bearing. The spring applies a force in a direction separating the bearing and the bracket. The spring applies an urging force that urges the bracket toward the board side. Here, the stator is provided with a pin extending toward the substrate side, and the pin penetrates the bracket and is joined to the substrate. Since there is a bracket between the substrate and the stator, the bracket may be displaced due to the urging force applied by the spring, which may cause a displacement in the position of the substrate. In the assembly process of the electric motor, if the bonding with the pin is performed while the position of the substrate is shifted, stress may be applied to the bonding portion after the electric motor is assembled, and the bonding reliability may be lowered.

  The present invention has been made in view of the above, and an object of the present invention is to obtain an electric motor capable of suppressing the displacement of the position of the substrate against the urging force that urges the bracket toward the substrate.

  In order to solve the above-described problems and achieve the object, the present invention includes a stator having a cylindrical shape, a frame that houses the stator, a rotor disposed inside the stator, and a rotor connected to the rotor. A shaft extending along the central axis of the stator; a first bearing provided on one side along the central axis with respect to the rotor; and holding the shaft rotatably about the central axis; and a first bearing A bracket provided on the opposite side of the rotor across the rotor and holding the first bearing, a substrate provided on the opposite side of the first bearing across the bracket, and a position of the rotor mounted on the substrate for detecting the position of the rotor An electric motor comprising a position detection unit and an urging force applying unit for applying an urging force for urging the bracket toward the substrate, wherein a convex portion is formed on one side of the stator and the bracket. Is, a concave portion is formed on the other side of the stator and the bracket, characterized in that the protrusion is press-fitted into the recess.

  The electric motor according to the present invention has an effect that the displacement of the position of the substrate can be suppressed against the urging force that urges the bracket toward the substrate.

1 is a side view of a DC brushless motor according to a first embodiment of the present invention. Partial expanded sectional view which expanded the A section shown in FIG. Top view of stator Sectional view seen along line BB shown in FIG. View of bracket viewed from bracket housing side The figure which looked at the bracket along the arrow C shown in FIG. Sectional drawing of the ventilation fan concerning Embodiment 2 of this invention

  Hereinafter, an electric motor and a ventilation fan according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a side view of the DC brushless motor according to the first embodiment of the present invention. FIG. 2 is a partially enlarged cross-sectional view in which the portion A shown in FIG. 1 is enlarged. FIG. 3 is a plan view of the stator. FIG. 4 is a cross-sectional view taken along line BB shown in FIG. In FIG. 1, the left side of the central axis 30 is shown as a cross-sectional view. In FIG. 1, hatching is omitted for easy understanding of the drawing.

  In the DC brushless motor 1 that is an electric motor, each element is housed inside an outer shell constituted by a frame 2 and a cover 8. The frame 2 has a bottomed cylindrical shape and is made of metal. A stator 3 having a cylindrical shape is press-fitted into the inner diameter of the frame 2. The stator 3 is configured by winding a coil 3b around an iron core 3a.

  Inside the stator 3, a rotor 6b having an annular shape is arranged. A shaft 6a extending along the central axis 30 of the stator 3 is connected to the rotor 6b. One end side of the shaft 6 a protrudes outside the frame 2. In the following description, one end side of the shaft 6a protruding outside from the frame 2 is referred to as a front side, and the other end side that is the opposite side is referred to as a rear side.

  The shaft 6a is provided with a front bearing 4a, which is a second bearing, on the front side of a connection portion with the rotor 6b, and a rear bearing 4b, which is a first bearing, on the rear side of the connection portion with the rotor 6b. Provided. Each of the bearings 4a and 4b holds the shaft 6a so as to be rotatable about the central axis 30. The front bearing 4 a is held by a housing 2 a formed on the frame 2.

  A bracket 7 for holding the rear bearing 4b is provided at a position opposite to the rotor 6b with the rear bearing 4b interposed therebetween. The bracket 7 is made of resin. The bracket 7 is formed with a bracket housing 7d that holds the rear bearing 4b. Between the bracket 7 and the rear bearing 4b, a spring 5 that is an urging force applying portion is provided. The spring 5 exerts a force in a direction in which the rear bearing 4 b and the bracket 7 are separated along the central axis 30. The spring 5 applies a force necessary for the rear bearing 4b to operate properly to the rear bearing 4b. Further, a biasing force that biases the bracket 7 toward the substrate 9 is applied to the bracket 7 by the spring 5.

  FIG. 5 is a view of the bracket 7 as seen from the bracket housing 7d side. FIG. 6 is a view of the bracket 7 taken along the arrow C shown in FIG. The bracket 7 has a disk shape as a whole so as to close the open portion of the frame 2. An outer peripheral portion of the bracket 7 is a bracket flange 7c, and is sandwiched between the frame flange 2b of the frame 2 and the cover flange 8a of the cover 8 as shown in FIG.

  As shown in FIGS. 2 and 5, the bracket 7 is formed with a bracket protrusion 7 a that protrudes toward the frame 2 and a cover-side protrusion 7 b that protrudes toward the cover 8. The bracket projection 7a is inserted inside the frame 2 along the inner periphery of the frame 2. The cover-side protrusion 7 b is inserted inside the cover 8 along the inner periphery of the cover 8. By inserting the bracket projection 7a inside the frame 2 and inserting the cover side projection 7b inside the cover 8, the center of the housing 2a and the center of the bracket housing 7d are aligned. The frame flange 2b, the bracket flange 7c, and the cover flange 8a are fixed with screws.

  A substrate 9 is provided on the opposite side of the rear bearing 4b with the bracket 7 interposed therebetween. The board 9 is provided with a Hall IC 31 that is a position detection unit for detecting the position of the rotor 6b, a drive circuit for rotating the rotor 6b, a power supply circuit, and electronic components constituting a microcomputer. In addition, illustration of a drive circuit and an electronic component is abbreviate | omitted.

  Holes for screwing and fixing the DC brushless motor 1 to the product are formed in the bracket flange 7c, the frame flange 2b, and the cover flange 8a. An example of a product to which the DC brushless motor 1 is fixed is a ventilation fan.

  As shown in FIGS. 3 and 4, the stator 3 is configured by winding an insulator 3d molded of resin for the purpose of insulation from the coil 3b on an iron core 3a, and then winding the coil 3b. The stator 3 is formed with pins 3 c that protrude toward the substrate 9. The end surface of the coil 3b is electrically joined to the pin 3c. The pin 3 c passes through the bracket 7, reaches the substrate 9, and is joined to the substrate 9. An example of the bonding between the substrate 9 and the pin 3c is a bonding using solder.

  Commercial AC power is applied to the substrate 9 from the outside, and the AC power is converted into a DC voltage by a power circuit, and power is supplied at a voltage corresponding to each element. The drive circuit mounted on the substrate 9 generates an alternating voltage so that a current flows in the intended direction with respect to the coil 3b through the pin 3c. The shaft 6a is rotated by the current flowing through the coil 3b.

  The microcomputer detects the induced voltage phase of the DC brushless motor 1 based on the signal of the Hall IC 31 which is a position detection unit, and performs control so that the induced voltage phase and the motor phase current phase generated from the drive circuit are the same phase. Do. The efficiency of the DC brushless motor 1 can be improved because the induced voltage phase and the motor phase current phase are the same phase.

  As shown in FIGS. 2, 3, and 4, a recess 3 e is formed in the iron core 3 a of the stator 3. As shown in FIGS. 2, 5, and 6, a protrusion 7 e that protrudes toward the stator 3 is formed on the bracket protrusion 7 a of the bracket 7. The concave portion 3e and the convex portion 7e are formed at positions overlapping each other when viewed along the central axis 30. Further, when the DC brushless motor 1 is assembled, the convex portion 7e is press-fitted into the concave portion 3e. The press-fitting strength of the convex portion 7 e into the concave portion 3 e is greater than the urging force applied by the spring 5. As shown in FIG. 6, a taper is provided at the tip of the convex portion 7e. Thereby, the improvement of the insertion property of the convex part 7e to the recessed part 3e can be aimed at.

  According to the DC brushless motor 1 described above, the stator 3 and the bracket 7 can be positioned relative to each other by fitting the concave portion 3e and the convex portion 7e. Further, since the convex portion 7e is press-fitted into the concave portion 3e, it is possible to suppress the bracket 7 from being displaced to the substrate 9 side due to the biasing force applied by the spring 5 and coming off or floating. Therefore, the board 9 can be prevented from being displaced by the bracket 7. That is, it is possible to prevent the substrate 9 from being displaced due to the biasing force applied by the spring 5.

  Therefore, the board | substrate 9 and the pin 3c can be joined in a suitable position. Here, when the substrate 9 is joined to the pin 3c while being displaced, stress is applied to the joint portion between the substrate 9 and the pin 3c when the substrate 9 is returned to an appropriate position in the subsequent assembly process. In some cases, the bonding reliability may decrease. On the other hand, in the DC brushless motor 1 according to the first embodiment, since the displacement of the substrate 9 can be suppressed, it is possible to improve the bonding reliability between the pins 3c and the substrate 9. Thereby, the reliability of the DC brushless motor 1 can be improved. In addition, a recessed part may be formed in the bracket 7 side, and a convex part may be formed in the stator 3 side.

  Further, since the bracket 7 is made of resin and has an insulating property, it is easy to secure a creeping distance in the radial direction between the coil 3b, the pin 3c and the substrate 9, and the frame 2 and the cover 8. Further, in the direction along the central axis 30, the coil 3 b and the bracket 7 can be brought into contact with each other, and the bracket 7 and the substrate 9 can be brought into contact with each other. Therefore, the DC brushless motor 1 can be reduced in size by shortening the distance between the coil 3b and the bracket 7 and the distance between the substrate 9 and the bracket 7. The bracket 7 is not limited to a resin one. The bracket 7 may be made of metal.

  In addition, a spring that applies a force in the direction of separating the front bearing 4a and the frame 2 may be inserted between the front bearing 4a and the frame 2. This spring also applies a biasing force that biases the bracket 7 toward the substrate 9. When springs are inserted into both the front bearing 4a side and the rear bearing 4b side, the spring is inserted into the front bearing 4a side and the spring 5 is inserted into the rear bearing 4b side. It is preferable to set so that the press-fitting strength of the convex portion 7e into the concave portion 3e is greater than the force.

Embodiment 2. FIG.
FIG. 7 is a cross-sectional view of the ventilation fan according to the second embodiment of the present invention. In FIG. 7, some hatching is omitted for easy understanding of the drawing. The ventilation fan 11 is configured by attaching the DC brushless motor 1 described in the first embodiment to a body 12. A blade 13 is fixed to the tip of the shaft 6 a of the DC brushless motor 1.

  The ventilation fan 11 has a structure in which a body 12 is installed on a ceiling plate 14 and a grill 15 is attached to the body 12. As the shaft 6a of the DC brushless motor 1 rotates and the blades 13 also rotate, an air flow indicated by an arrow D in FIG. 7 is generated.

  As shown in FIG. 1, in the DC brushless motor 1, a circuit part provided with a substrate 9 and a motor part provided with a rotor 6 b and a stator 3 are partitioned by a bracket 7. Therefore, the motor part is exposed to the air flow, but the circuit part is a space that is cut off from the air flow, so that it is difficult to become a high humidity space. Therefore, the ventilation fan 11 provided with the DC brushless motor 1 can be used for ventilation in a high humidity atmosphere. An example of the high humidity atmosphere is a bathroom. In addition, the ventilation fan 11 can be reduced in size by reducing the size of the DC brushless motor 1. Thereby, it can be set as the ventilation fan 11 which is easy to install in the ceiling back with a limited space.

  The configuration described in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and can be combined with other configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

  1 DC brushless motor (electric motor), 2 frame, 2a housing, 3 stator, 3a iron core, 3b coil, 3c pin, 3e recess, 4a front bearing (second bearing), 4b rear bearing (first bearing), 5 Spring (biasing force applying part), 6a Shaft, 6b Rotor, 7 Bracket, 7e Convex part, 9 Substrate, 11 Ventilation fan, 12 Body, 13 Blades, 30 Central axis, 31 Hall IC (position detection part).

Claims (5)

A stator having a cylindrical shape;
A frame for accommodating the stator therein;
A rotor disposed inside the stator;
A shaft coupled to the rotor and extending along a central axis of the stator;
A first bearing that is provided on one side of the rotor along the central axis and holds the shaft rotatably about the central axis;
A bracket that is provided on the opposite side of the rotor across the first bearing, and holds the first bearing;
A substrate provided on the opposite side of the first bearing across the bracket;
A position detector that is mounted on the substrate and detects the position of the rotor;
An urging force applying unit that applies an urging force that urges the bracket toward the substrate;
A convex portion is formed on one side of the stator and the bracket,
A recess is formed on the other side of the stator and the bracket,
The electric motor, wherein the convex portion is press-fitted into the concave portion.   The biasing force applying portion is a spring that is provided between the first bearing and the bracket and applies a force in a direction in which the first bearing and the bracket are separated along the central axis. The electric motor according to claim 1. A second bearing that is provided on the other side along the central axis with respect to the rotor and that holds the shaft rotatably about the central axis;
The second bearing is held by the frame,
The biasing force applying portion is a spring that is provided between the second bearing and the frame and applies a force in a direction to separate the second bearing and the frame along the central axis. The electric motor according to claim 1.   The electric motor according to any one of claims 1 to 3, wherein the bracket is made of resin. An electric motor according to any one of claims 1 to 4,
Blades connected to the shaft;
And a body that houses the blades therein.

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