JP5268845B2 - DC brushless motor and ventilation fan - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a DC brushless motor wherein the productivity is enhanced, stresses are less apt to be generated in electronic components, and poor electrical connection is less apt to be produced. <P>SOLUTION: The direct-current brushless motor includes a metal frame; a stator on which a coil is wound and which is fit to the frame; a pin which is erected behind the stator and around which an end of the coil is entwined; a resin bracket, with a rear bearing holding portion formed in the center thereof and an outer cylinder portion and a through-hole formed in the outer circumferential portion thereof, the outer cylinder portion being press-fit in the frame from behind the stator and the through hole having the pin inserted therein; a damp-proof seal that closes the through-hole, with the pin inserted therein; a rotor placed in the stator; a circuit board mounted with an electronic component placed behind the bracket and conductively connected to the pin; and a metal cover on the outer circumferential portion of the front end of which a cover flange fastened together with a frame flange of the frame is formed and which is fit onto the outer cylinder portion of the bracket and fastened to the frame, and is brought into contact with the electronic component and radiates heat. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a DC brushless motor and a ventilation fan in which a blower fan is driven by the DC brushless motor.

  Conventionally, a rotor, a stator, and the like are confined in a case, a sensor for detecting the rotation of the rotor, a peripheral circuit to which an output signal of the sensor is supplied, and a one that is rotationally driven according to the output signal of the peripheral circuit In an electric motor including a chip inverter, the one-chip inverter, the sensor, and the peripheral circuit are arranged on the bottom surface of the case and molded with a mold resin, and the case serves as a heat dissipation means for the one-chip inverter and is moisture resistant. An electric motor with improved performance is disclosed (for example, see Patent Document 1).

JP 2001-128417 A (4th and 5th pages, FIGS. 1 and 2)

  However, according to the above conventional technique, the one-chip inverter, the sensor, and the peripheral circuit are molded with the mold resin in the case. For this reason, there is a problem that the molding resin requires a curing time in the manufacturing process and the productivity is poor. In addition, there is a problem that stress is easily generated in the electronic component due to the difference between the thermal strain amount of the mold resin and the thermal strain amount of the electronic component, and the electronic component is likely to fail. Furthermore, there is a problem that poor connection occurs when the lower case and the stator coil are electrically connected.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a DC brushless motor that is highly productive, hardly generates stress in electronic components, and hardly causes poor electrical connection.

  In order to solve the above-described problems and achieve the object, the present invention includes a metal frame in which a front bearing holding portion is formed in the center of the front end plate and a frame flange is formed in the rear end outer peripheral portion of the cylindrical body portion. A stator in which a coil is wound and fitted in a cylindrical body portion of the frame, a pin standing on the rear side of the stator and entangled with the end of the coil, and a rear bearing holding portion formed in the center An outer cylinder part and a through hole are formed in the part, and after the stator, the outer cylinder part is press-fitted into the cylindrical body part of the frame and the pin is inserted into the through hole, and the pin A moisture-proof seal that closes the inserted through-hole, a rotor that is held in the front bearing holding portion of the frame and a rear bearing is held in the rear bearing holding portion of the bracket and disposed in the stator, a power supply circuit, Configure the drive circuit A circuit board on which electronic components are mounted and disposed on the rear side of the bracket and conductively connected to the pins, and a cover flange that is fastened to the frame flange are formed on the outer periphery of the front end, and a cylindrical body is formed on the outer cylinder portion of the bracket A metal cover that is externally fitted and fastened to the frame to dissipate heat of the electronic component by contacting the electronic component.

  According to the present invention, it is possible to obtain a DC brushless motor that is highly productive, hardly generates stress in an electronic component, and hardly causes poor electrical connection.

FIG. 1 is a partial cross-sectional view showing a first embodiment of a DC brushless motor according to the present invention. FIG. 2 is an enlarged view of part A in FIG. FIG. 3 is a partial cross-sectional view showing a second embodiment of the DC brushless motor according to the present invention. FIG. 4 is a partial sectional view showing a third embodiment of the DC brushless motor according to the present invention. FIG. 5 is an enlarged view of a portion B in FIG. FIG. 6 is a sectional view of a ventilation fan equipped with a DC brushless motor according to the present invention.

  Embodiments of a DC brushless motor and a ventilation fan according to the present invention will be described below 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 partial sectional view showing a first embodiment of a DC brushless motor according to the present invention, and FIG. 2 is an enlarged view of a portion A in FIG. As shown in FIGS. 1 and 2, the DC brushless motor 91 according to the first embodiment has a front bearing holding portion 1a formed at the center of the front end plate 1t, and a frame flange 1b at the outer peripheral portion of the rear end of the cylindrical body 1d. A metal frame 1 formed in a cap shape as a whole, an iron core 2b around which a coil 2a is wound, a stator 2 fitted in a cylindrical body 1d of the frame 1, and a shaft 3a. The front bearing 3b and the rear bearing 3c are fitted and the front bearing 3b is held in the front bearing holding portion 1a of the frame 1 so that the rotor 3 is disposed in the stator 2, and the rear bearing holding that holds the rear bearing 3c in the center. Part 4a is formed, outer cylinder part 4b is formed on the outer periphery, and resin cylinder-like bracket 4 in which outer cylinder part 4b is press-fitted into cylindrical body part 1d of frame 1 after stator 2 is provided. ing.

  The bracket 4 is positioned in the axial direction by bringing the front end face into contact with the rear end face of the iron core 2b. The outer diameter of the outer cylindrical portion 4 b of the bracket 4 is formed to be a size that is a squeeze to the inner diameter of the frame 1. Moreover, the outer peripheral surface of the outer cylinder part 4b of the bracket 4 is in contact with the inner peripheral surface of the frame 1 over the entire periphery. The front bearing 3 b is held by the front bearing holding portion 1 a of the frame 1, and the rear bearing 3 c is held by the rear bearing holding portion 4 a of the bracket 4.

  On the outer peripheral portion of the bracket 4 (inside the outer tube portion 4b), three axial through holes 4c are formed. A pin 2c erected on the rear side of the stator 2 is inserted into the through hole 4c. The pin 2 c electrically connects the terminal of the coil 2 a of the stator 2 and the circuit board 5.

  The through-hole 4c is a tapered hole so that the inner diameter on the stator 2 side (motor section 11 side) is large and the inner diameter on the circuit board 5 side (circuit section 12 side) is small so that the gap with the pin 2c is small. After the pin 2c is inserted into the through hole 4c, a quick-drying moisture-proof seal 6 is provided so as to close the gap with the pin 2c in order to prevent air from entering from the motor unit 11 side to the circuit unit 12 side.

  The circuit board 5 is attached (arranged) to the circuit part 12 side of the bracket 4 so that the pin 2c is inserted, and the pin 2c and the circuit board 5 are conductively connected by solder or the like. On the circuit board 5, electronic components 7 constituting a drive circuit, a power supply circuit, and the like for rotating the DC brushless motor 91 are mounted.

  The cylindrical body portion 8d of the metal cover 8 is fitted on the outer tube portion 4b of the bracket 4, and the cover flange 8b formed on the outer peripheral portion of the front end of the cover 8 is brought into contact with the frame flange 1b and fastened with screws or the like. To do. An annular throttle portion 8a is formed on the rear end plate 8t of the cover 8, and the bottom surface of the throttle portion 8a comes into contact with the electronic component 7 such as a heat generating IC or a diode bridge to cover the heat of the electronic component 7. Heat is released from the surface of 8.

  When a commercial AC voltage is applied from the outside, the AC voltage is converted to a DC voltage by a power circuit (not shown) mounted on the circuit board 5 and is switched by a drive circuit (not shown). The stator 2 is connected via a pin 2c. A current in a predetermined direction flows through the coil 2a, and the rotor 3 rotates.

  Since the bracket 4 is made of resin such as PPS and has an insulating property, a creeping distance in the radial direction between the coil 2a, the pin 2c and the circuit board 5, the frame 1 and the cover 8 can be secured. Further, the space between the coil 2a and the bracket 4 and the space between the circuit board 5 and the bracket 4 are unnecessary (may be brought into contact), and the axial dimension of the DC brushless motor 91 is reduced. Can do.

  Since the bracket 4 is positioned in the axial direction by bringing the front end face into contact with the rear end face of the iron core 2b, the bracket 4 does not tilt with respect to the axis. Further, since the bracket 4 is press-fitted into the frame 1, the degree of coaxiality between the front bearing holding portion 1a of the frame 1 and the rear bearing holding portion 4a of the bracket 4 is high, and the shaft 3a and the rotor 3 can be assembled with high accuracy. Can do.

  Since the through hole 4c is a tapered hole having a large inner diameter on the motor unit 11 side, a space for tying the end of the coil 2a to the pin 2c is secured, and when the bracket 4 is press-fitted into the frame 1, There is no fear that the connected terminal will break.

  Since the bracket 4 is press-fitted into the frame 1 and the moisture-proof seal 6 is provided in the through hole 4c so as to close the gap with the pin 2c, the motor part 11 and the circuit part 12 can be separated in an airtight manner. And adverse effects such as moisture and condensation in the circuit section 12 can be avoided. Since the moisture resistance performance of the circuit unit 12 is high, it is possible to reduce the working time and the number of processes for molding and potting.

  Since the bottom surface of the narrowed portion 8a of the cover 8 comes into contact with the electronic component 7 and the heat of the electronic component 7 is dissipated from the entire surface of the cover 8, an increase in temperature of the electronic component 7 can be suppressed.

  Further, a heat-dissipating sheet having insulating properties and cushioning properties may be interposed between the electronic component 7 and the bottom surface of the throttle portion 8a. In this way, the pressure applied to the electronic component 7 due to an assembly error in the axial direction. Can be absorbed by the heat dissipation sheet.

  Further, even when the DC brushless motor 91 is abnormal (failure due to a temperature rise or the like of the electronic component 7), the electronic component 7 or the like is covered with the metal cover 8, so that it can be safely stopped.

Embodiment 2. FIG.
FIG. 3 is a partial cross-sectional view showing a second embodiment of the DC brushless motor according to the present invention. As shown in FIG. 3, in the DC brushless motor 92 of the second embodiment, a bracket flange 24f is provided on the outer peripheral portion of the outer cylinder portion 24b of the bracket 24, and the bracket flange 24f is sandwiched between the frame flange 1b and the cover flange 8b. The bracket 24 is positioned in the axial direction.

  The outer diameter of the bracket flange 24f is the same as the outer diameter of the frame flange 1b and the cover flange 8b, and the thickness is 1 mm or more. By sandwiching and fixing the bracket flange 24f between the frame flange 1b and the cover flange 8b, the bracket 24 press-fitted into the frame 1 is prevented from being displaced in the axial direction due to a difference in thermal expansion coefficient between resin and metal. Can do.

Embodiment 3 FIG.
FIG. 4 is a partial cross-sectional view showing a third embodiment of the DC brushless motor according to the present invention, and FIG. 5 is an enlarged view of portion B of FIG. As shown in FIGS. 4 and 5, the DC brushless motor 93 according to the third embodiment has a plurality of (for example, 3 at regular intervals on the circumference) that protrudes inward from the cylindrical body of the cover 38 by a punch or the like. The projection 38t is provided at a location where the rear end portion of the outer cylinder portion 4b of the bracket 4 pressed into the frame 1 and abutted against the stator 2 is pressed by the projection 38t.

  In the DC brushless motor 93 according to the third embodiment, even if the bracket 4 expands or contracts due to a temperature change, the axial position of the bracket 4 does not shift.

Embodiment 4 FIG.
FIG. 6 is a sectional view of a ventilation fan equipped with a DC brushless motor according to the present invention. As shown in FIG. 6, any of the DC brushless motors 91 to 93 of the first to third embodiments is mounted on the body 41 of the ventilation fan 100, and the blower fan 42 is attached to the shaft 3a. The body 41 is installed on the ceiling plate 43 and the grille 44 is attached to the body 41 from below.

  When the DC brushless motors 91 to 93 are rotated and the blower fan 42 is rotated, an air flow indicated by an arrow in FIG. 6 is generated. As described in the first embodiment, in the DC brushless motor 91 (92, 93), the circuit unit 12 and the motor unit 11 are partitioned by the bracket 4, and the motor unit 11 is exposed to the air flow. Since the circuit unit 12 is a space cut off from the air flow, the circuit unit 12 does not have high humidity but can be used for ventilation in a high humidity atmosphere such as a bathroom. Moreover, since the DC brushless motors 91 to 93 can be reduced in size, the ventilation fan 100 can be reduced in size and can be easily installed on the back of the ceiling.

  As described above, the DC brushless motor and the ventilation fan according to the present invention are suitable for a bathroom ventilation fan.

DESCRIPTION OF SYMBOLS 1 Frame 1a Front bearing holding | maintenance part 1b Frame flange 1d Cylindrical trunk | drum 1t Front end plate 2 Stator 2a Coil 2b Iron core 2c Pin 3 Rotor 3a Shaft 3b Front bearing 3c Rear bearing 4 Bracket 4a Rear bearing holding part 4b Outer cylinder part 4c Through-hole DESCRIPTION OF SYMBOLS 5 Circuit board 6 Moisture-proof seal 7 Electronic component 8 Cover 8a Restriction part 8b Cover flange 8d Cylindrical trunk part 8t Rear end plate 11 Motor part 12 Circuit part 24 Bracket 24b Outer cylinder part 24f Bracket flange 38 Cover 38t Projection 41 Body 42 Fan 43 Ceiling panel 44 Grill 91, 92, 93 DC brushless motor 100 Ventilation fan

Claims (6)

A metal frame in which a front bearing holding portion is formed in the center of the front end plate and a frame flange is formed on the outer peripheral portion of the rear end of the cylindrical body portion;
A stator wound with a coil and fitted into the cylindrical body of the frame;
A pin erected on the rear side of the stator and entangled with the end of the coil;
A rear bearing holding part is formed in the center, an outer cylinder part and a through hole are formed in the outer peripheral part, the outer cylinder part is press-fitted into the cylindrical body part of the frame from the rear of the stator, and the pin is inserted into the through hole. Plastic brackets,
A moisture-proof seal that closes the through-hole through which the pin is inserted;
A rotor in which a front bearing is held in a front bearing holding portion of the frame and a rear bearing is held in a rear bearing holding portion of the bracket and disposed in the stator;
A circuit board on which electronic components constituting a power supply circuit and a drive circuit are mounted and disposed on the rear side of the bracket and conductively connected to the pins;
A cover flange to be fastened to the frame flange is formed on the outer peripheral portion of the front end, and a cylindrical body is externally fitted to the outer tube portion of the bracket to be fastened to the frame and to contact the electronic component to heat the electronic component. A metal cover that dissipates heat,
A DC brushless motor comprising:   2. The DC brushless motor according to claim 1, wherein the through hole of the bracket is a tapered hole having a large inner diameter on the stator side and a small inner diameter on the circuit board side.   The DC brushless motor according to claim 1 or 2, wherein the electronic component and the cover are brought into contact with each other with a heat dissipation sheet interposed therebetween.   2. A bracket flange is provided on an outer peripheral portion of an outer cylinder portion of the bracket, and the bracket flange is sandwiched between the frame flange and the cover flange to position the bracket in the axial direction. DC brushless motor as described in any one of -3.   A plurality of projections projecting inward are provided on the cylindrical body portion of the cover, and the rear end portion of the outer cylinder portion of the bracket that is press-fitted into the frame and is in contact with the stator is pressed by the projection. The DC brushless motor according to any one of claims 1 to 3.   The ventilation fan by which a ventilation fan is driven with the DC brushless motor as described in any one of Claims 1-5.

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