JP5455784B2 - DC motor and ventilation fan - Google Patents

Description

  The present invention relates to a brushless DC motor and a ventilation fan equipped with the DC motor.

  A control circuit for driving and controlling a brushless DC motor includes a power supply circuit that converts an AC power source into a DC power source, and an inverter circuit that generates an AC voltage applied to the stator winding of the DC motor from the converted DC power source. Although configured, the switching power supply in the power supply circuit and the switching circuit in the inverter circuit both generate noise. Therefore, a noise filter for suppressing noise passing through the power supply line is provided on the AC input side of the power supply circuit.

  The noise filter includes an X capacitor for countermeasures against normal mode noise, a Y capacitor for countermeasures against common mode noise, and a common mode choke coil. The X capacitor is connected between the two power supply lines. The Y capacitor is connected between one side of the power supply line and ground (circuit ground of the circuit board).

  In such a noise filter, the expected noise suppression effect cannot be obtained if the ground lead wire connecting the ground side (ie, circuit ground) of the Y capacitor and the ground (ground) becomes long. For this reason, various proposals have conventionally been made for the processing method on the ground side of the Y capacitor (for example, Patent Document 1, Patent Document 2, etc.).

Japanese Utility Model Publication No. 5-15666 JP 2010-7974 A

  However, in the above conventional technique, the ground lead wire is still used to connect between the Y capacitor and the earth (ground), so that a resistance component and an inductance component generated between the Y capacitor and the earth (ground), That is, the impedance may increase and the filter characteristics may deteriorate.

  Moreover, the conventional ventilation fan has a configuration in which a DC motor is mounted, and the control circuit of the DC motor is divided into a power supply circuit and an inverter circuit, and the circuit board on which the inverter circuit is mounted is built in the outer frame housing of the DC motor, The circuit board on which the power supply circuit is mounted employs a shape that is externally attached to the outer frame housing of the DC motor. In this configuration, the circuit ground of the built-in circuit board and the circuit ground of the external circuit board (the ground side of the Y capacitor) are connected to the case of the ventilation fan by a common ground lead wire.

  Therefore, in the conventional ventilation fan, the noise suppression effect changes depending on how the ground lead wire is routed, and stable filter characteristics cannot be obtained. In addition, the size of the ventilation fan varies depending on the model, so it is necessary to change the length of the ground lead wire for each model, which makes it difficult to standardize the placement position of external circuit boards and mounted components, and increases costs. Yes. In addition, the built-in circuit board has a long ground lead wire, so the high-frequency current flowing through the stray capacitance between the switching circuit and the circuit ground cannot be ignored. Even if a noise filter is mounted on the external circuit board, noise is not generated. The situation is such that it cannot be effectively reduced.

  The present invention has been made in view of the above, and the ground side of the Y capacitor is held at a low impedance only by fixing the outer frame housing incorporating all of the control circuits including the noise filter to the mounting target device. An object of the present invention is to obtain a DC motor with a built-in control circuit that can reliably perform grounding.

  It is another object of the present invention to provide a ventilation fan in which the DC motor of the present invention is mounted so as to ensure stable filter characteristics, and the cost can be reduced by standardization in parallel with the noise reduction of the DC motor.

  In order to achieve the above-described object, the present invention provides an outer frame housing comprising a bottomed cylindrical motor frame that houses a motor portion including a stator and a rotor, and a motor bracket that closes the opening end of the motor frame. Based on a PWM drive signal, a filter circuit composed of a noise filter in the body, a power supply circuit that converts an AC power supply input through the filter circuit into a DC power supply, and a DC voltage output by the power supply circuit A DC motor having a circuit board mounted with a control circuit having an inverter circuit for switching and outputting a motor driving voltage to be applied to the stator winding, the ground side of the Y capacitor of the noise filter being connected The circuit ground of the circuit board and the outer frame housing are connected with a low impedance. .

  According to the present invention, all of the control circuit including the noise filter is built in the outer frame casing of the DC motor, and between the ground side (circuit ground) of the Y capacitor and the ground (outer frame casing), Connected with low impedance. Then, simply by incorporating the DC motor into the ventilation fan, the grounding process for connecting the earth side (circuit earth) of the Y capacitor and the earth (ground) can be reliably performed through the ventilation fan housing. Therefore, a DC motor having an excellent noise reduction effect can be operated with stable filter characteristics, and a DC motor and a ventilation fan with less noise can be obtained. In addition, there is no need for an earth lead wire that connects the earth side (circuit earth) of the Y capacitor and the earth (ground), so the cost of the earth lead wire can be reduced, and the length of the earth lead wire for each model There is no need to change the sheath routing, and there is an effect that a DC motor and a ventilation fan that can be standardized are obtained.

FIG. 1 is a cross-sectional view showing the arrangement of a DC motor according to Embodiment 1 of the present invention. FIG. 2 is a block diagram showing an example of a control circuit mounted on the circuit board shown in FIG. FIG. 3 is a cross-sectional view showing the arrangement configuration of the DC motor according to the second embodiment of the present invention. FIG. 4 is a cross-sectional view showing the arrangement of the DC motor according to Embodiment 3 of the present invention. FIG. 5 is a schematic external configuration diagram of a ventilation fan according to Embodiment 4 of the present invention.

  Embodiments of a DC 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 cross-sectional view showing the arrangement of a DC motor according to Embodiment 1 of the present invention. FIG. 2 is a block diagram showing an example of a control circuit mounted on the circuit board shown in FIG. In FIG. 1, the outer frame housing of the DC motor 1 a includes a bottomed cylindrical motor frame 2 and a motor bracket 3 that is a cover that closes an opening of the motor frame 2. The motor frame 2 and the motor bracket 3 are each made of metal, and flanges 2a and 3a that can be screwed to each other are provided on the outer peripheral edge.

  The outer frame housing of the DC motor 1a is partitioned by a housing 4 into a motor partial housing portion on the motor frame 2 side and a control circuit housing portion on the motor bracket 3 side. The housing 4 is formed by pressing a resin material in a concavo-convex shape, and an outer peripheral edge thereof is fixed to an inner peripheral surface at a position close to the opening of the motor frame 2.

  A stator core 5 and a rotor 6 are arranged in the motor partial storage portion. The stator core 5 has a stator winding 5c wound around an iron core 5b formed of 12 slots spaced 30 degrees apart on the inner periphery of the core back 5a. The stator core 5 is divided into three phases (U phase, V phase, W) at 60 degree intervals. Phase) windings are arranged.

  The stator core 5 shown in FIG. 1 is a cross-sectional cut view of one of three phases and a ground pin 17 arranged at an interval of 180 degrees. The stator core 5 is disposed such that the outer peripheral surface of the core back 5 a is in close contact with the inner peripheral surface of the motor frame 2. Then, both axial ends of the stator core 5 are covered with resin layers 7a and 7b.

  The rotor 6 is composed of a permanent magnet and is fixed to the shaft 8. The shaft 8 is rotatably supported by bearings 9 a and 9 b at the cylindrical center position of the motor frame 2. The bearing 9 a is fixed to the housing 4 and rotatably supports one end of the shaft 8. The bearing 9 b is fixed to the bottom of the motor frame 2 and rotatably supports the other end side of the shaft 8 protruding outward from the bottom of the motor frame 2.

  In the control circuit housing portion, the circuit board 10 is positioned and fixed to the housing 4. All of the control circuits are mounted on the circuit board 10. However, FIG. 1 shows the main configuration of the control circuit. That is, FIG. 1 shows a connector portion 12 connected to an AC input connector 11 provided on the motor bracket 3, a filter circuit 13, a power supply circuit 14, and an inverter circuit 15. Although not shown in FIG. 1, as another component of the control circuit, a sensor for detecting the magnetic pole position of the rotor 6 is arranged at a location close to the rotor 6 on the circuit board 10. Hall elements are widely used as magnetic pole position sensors.

  One end of the coil pin 16 is fixed to the resin layer 7 a that covers the housing 4 side of the stator core 5. The coil pin 16 is made of annealed copper wire and is provided for three phases. One end of each is solder-connected to one end of the corresponding stator winding between the resin layer 7a and the housing 4, and the other end is connected to the circuit board. 10 is pattern-connected to the corresponding output terminal of the switching circuit in the inverter circuit 15.

  In addition, the ground pin 17 is made of a terminal member made of a conductive metal such as copper or brass. One end of the ground pin 17 is inserted into the core back 5a of the stator core 5 through the resin layer 7a, and the other end is inserted through the circuit board 10. The other end side periphery is solder-connected to the circuit ground of the circuit board 10. One end of the ground pin 17 may be press-fitted and fixed to the iron core 5b.

  Next, the control circuit mounted on the circuit board 10 will be specifically described. In FIG. 2, AC power (AC 100 V) input to the connector unit 12 is input to the power circuit 14 through the fuse 17 and the filter circuit 13 and converted to DC power, and the AC required by the inverter circuit 15. Converted to power.

  The filter circuit 13 includes an X capacitor Cx, a common mode choke coil L, and Y capacitors Cy1 and Cy2 that constitute a noise filter. The X capacitor Cx is connected between two lines of the AC power supply. The common mode choke coil L is inserted in two lines of the AC power source. One end of each of the Y capacitors Cy <b> 1 and Cy <b> 2 is connected to one of the two lines of the AC power supply, and the other end on the ground side is connected to the circuit ground of the circuit board 10. 2 shows a case where the X capacitor Cx is arranged on one end side (power supply input side) of the common mode choke coil L, but also on the other end side (power supply circuit side) of the common mode choke coil L. May be placed. Further, if necessary, a lightning surge absorber may be connected between one end of the AC power source and the circuit ground (omitted in FIG. 2).

  The power supply circuit 14 includes a rectifier circuit 14a, a smoothing capacitor 14b, and a switching power supply 14c. The inverter circuit 15 includes a drive circuit 15a and a switching circuit 15b. In FIG. 1, a magnetic pole position sensor 18 is shown. The magnetic pole position of the rotor 6 detected by the magnetic pole position sensor 18 is input to the drive circuit 15a.

  In the power supply circuit 14, the AC power input through the filter circuit 13 is full-wave rectified by a rectifier circuit 14a using a diode bridge, converted to a DC power, and stored in the smoothing capacitor 14b. The smoothing capacitor 14b generates a DC power source (for example, DC 140V) required by the switching circuit 15b. The switching power supply 14c generates a control power supply (for example, DC15V) required by the drive circuit 15a from the direct current power generated in the smoothing capacitor 14b.

  The switching circuit 15b has a U-phase, V-phase, and W-phase three-phase bridge configuration formed between the positive electrode bus P and the negative electrode bus N. The positive electrode bus P is connected to the positive electrode end of the smoothing capacitor 14b, and the negative electrode bus N is connected to the negative electrode end of the smoothing capacitor 14b. The three transistors on the positive bus P side are upper arm transistors, and the three transistors on the negative bus N side are lower arm transistors. A free-wheeling diode is connected to each switching element in antiparallel. The connection ends of the upper and lower arm transistors constitute an output end and are connected to the U-phase, V-phase, and W-phase stator windings 5c.

  The drive circuit 15a generates a PWM signal for driving on and off the six switching elements in the switching circuit 15b. At that time, a PWM signal is generated in accordance with the magnetic pole position input from the magnetic pole position sensor 18 so that the desired stator winding 5c can be energized. Thereby, the rotor 6 rotates and the shaft 8 rotates.

  In FIG. 1, the high-frequency current generated during the operation of the switching power supply in the power supply circuit 14 and the switching circuit in the inverter circuit 15 is in the path of the Y capacitor in the filter circuit 13 → the ground pin 17 → the stator core 5 → the motor frame 2. Flowing. When the motor frame 2 that is a part of the outer frame casing is connected to the casing of the mounting target device to be incorporated, the motor frame 2 is connected to the ground via the mounting target device and grounded.

  As described above, according to the first embodiment, all of the control circuit including the noise filter is incorporated in the outer frame casing of the DC motor, and the stator core is closely attached to the inner peripheral surface of the outer frame casing. Since the circuit ground of the circuit board to which the ground side of the Y capacitor is connected and the stator core are connected by the low impedance terminal member (ground pin 17), the DC motor is incorporated into the device to be mounted, and the ground side of the Y capacitor The grounding process for connecting between (circuit ground) and ground (ground) can be reliably performed through the target device.

  Therefore, a control circuit built-in type DC motor having an excellent noise reduction effect can be obtained. Further, since the earth lead wire for connecting the earth side (circuit earth) of the Y capacitor and the earth (ground) is unnecessary, the cost of the earth lead wire can be reduced.

Embodiment 2. FIG.
FIG. 3 is a cross-sectional view showing the arrangement of the DC motor according to the second embodiment of the present invention. In FIG. 3, components that are the same as or equivalent to the components shown in FIG. 1 (Embodiment 1) are given the same reference numerals. Here, the description will be focused on the portion related to the second embodiment.

  As shown in FIG. 3, in the DC motor 1b according to the second embodiment, in the configuration shown in FIG. 1 (the first embodiment), one end of the ground pin 17 is not press-fitted into the stator core 5 and is fixed to the resin layer 7a. ing. A ground guide 22 having a length that allows the tip to contact the other end of the ground pin 17 is provided at a predetermined position on the inner peripheral surface of the motor bracket 3 corresponding to the other end position of the ground pin 17 protruding from the circuit board 10. ing.

  In this configuration, since the earth guide 22 is composed of a terminal member, when the motor bracket 3 is fixed to the motor frame 2, the other end of the earth pin 17 is connected to the motor bracket 3 via the earth guide 22 with low impedance. .

  Then, the high-frequency current generated during the operation of the switching power supply in the power supply circuit 14 and the switching circuit in the inverter circuit 15 flows through the path of the Y capacitor in the filter circuit 13 → the earth pin 17 → the earth guide 22 → the motor bracket 3. When the motor bracket 3 which is a part of the outer frame housing is connected to the housing of the mounting target device to be incorporated, the motor bracket 3 is connected to the ground via the mounting target device and grounded.

  In the second embodiment, the arrangement mode of the stator core 5 (contact / non-contact with the inner peripheral surface of the motor frame 2) may be the same as or different from the first embodiment.

  As described above, according to the second embodiment, all of the control circuit including the noise filter is built in the outer frame housing of the DC motor, and the outer frame housing (motor bracket 3) and the circuit ground are connected with low impedance. Since the terminal member (the ground pin 17 and the ground guide 22) is connected, the grounding process for connecting the ground side (circuit ground) of the Y capacitor and the ground (ground) can be performed only by incorporating the DC motor into the target device. It can be done reliably through the target equipment.

  Therefore, as in the first embodiment, a control circuit built-in DC motor having an excellent noise reduction effect can be obtained. Further, since the earth lead wire for connecting the earth side (circuit earth) of the Y capacitor and the earth (ground) is unnecessary, the cost of the earth lead wire can be reduced.

Embodiment 3 FIG.
FIG. 4 is a cross-sectional view showing the arrangement of the DC motor according to Embodiment 3 of the present invention. In FIG. 4, components that are the same as or equivalent to the components shown in FIG. 1 (Embodiment 1) are assigned the same reference numerals. Here, the description will be focused on the portion related to the third embodiment.

  As shown in FIG. 4, the DC motor 1 c according to the third embodiment has the configuration shown in FIG. 1 (the first embodiment) except that the ground pin 17 is omitted and a ground connection piece 24 is provided. The ground connection piece 24 is formed in such a form that the other end contacts the circuit ground of the circuit board 10 when one end is sandwiched between the flange 2 a of the motor frame 2 and the flange 3 a of the motor bracket 3.

  In this configuration, since the ground connection piece 24 is composed of a terminal member, when the motor frame 2 is fixed to the motor bracket 3 with the other end of the ground connection piece 24 in contact with the circuit ground of the circuit board 10, The circuit ground of the circuit board 10 and the outer frame casing are connected with low impedance through the ground connection piece 24.

  Then, the high-frequency current generated during the operation of the switching power supply in the power supply circuit 14 and the switching circuit in the inverter circuit 15 flows through the path of the Y capacitor in the filter circuit 13 → the ground connection piece 24 → the outer frame housing. When the outer frame housing of the DC motor 1c is connected to the housing of the mounting target device to be incorporated, it is connected to the ground via the mounting target device and grounded.

  In the third embodiment, the arrangement mode of the stator core 5 (whether it is in contact with the inner peripheral surface of the motor frame 2) may be the same as or different from the first embodiment.

  Thus, according to the third embodiment, all of the control circuit including the noise filter is built in the outer frame casing of the DC motor, and the outer frame casing and the circuit ground are connected to the low-impedance terminal member (ground). Since the connection piece 24) is connected, the grounding process for connecting the ground side (circuit ground) of the Y capacitor and the ground (ground) can be reliably performed through the mounting target device by simply incorporating the DC motor into the mounting target device. .

  Therefore, as in the first embodiment, a control circuit built-in DC motor having an excellent noise reduction effect can be obtained. Further, since the earth lead wire for connecting the earth side (circuit earth) of the Y capacitor and the earth (ground) is unnecessary, the cost of the earth lead wire can be reduced.

Embodiment 4 FIG.
FIG. 5 is a schematic external configuration diagram of a ventilation fan according to Embodiment 4 of the present invention. In FIG. 5, the ventilation fan 30 according to the fourth embodiment is equipped with the DC motor 1a described in the first embodiment. The DC motors 1b and 1c described in the second and third embodiments are also mounted on the ventilation fan 30 in the manner shown in FIG.

  The DC motor 1 a is mounted on the ventilation fan 30 by fixing the outer frame housing to the ventilation fan body 32 with screws 33 in a state where the fan 31 is attached to the shaft 8. The ventilation fan body 32 is provided with a power connection terminal block 34 and a ground connection terminal 35.

  The AC input connector 11 of the DC motor 1 a is connected to the power connection terminal block 34. The power connection terminal block 34 has one external connection terminal connected to one power line of an AC 100V AC power source 37 via a switch 36 and the other external connection terminal directly connected to the other power line of the AC 100V AC power source 37. It is connected. That is, the DC motor 1a is energized / interrupted by turning on / off the switch 36. When the switch 36 is turned on and the DC motor 1a is energized, the fan 31 connected to the shaft 8 of the DC motor 1a rotates and the room is ventilated.

  The ground terminal block 35 is grounded to be connected to the ground by a ground wire 38. The ventilation fan body 32 may be made of metal or may not be made of metal. If not made of metal, the fastening location of the screw 33 and the location of the ground terminal block 35 are connected by a metal plate. That is, when the DC motor 1 a is screwed and fixed to the ventilation fan body 32, the outer frame housing of the DC motor 1 a is automatically grounded through the ventilation fan body 32.

  Therefore, the high-frequency current generated during the operation of the switching power supply in the power supply circuit 14 and the switching circuit in the inverter circuit 15 during the process of turning on the switch 36 and energizing the DC motor 1a to ventilate the room is DC It flows in the route of the outer frame housing of the motor 1a → the ground connection terminal 35 of the ventilation fan body 32 → the ground wire 38 → the ground (ground).

  Thus, according to the fourth embodiment, since the ventilation fan body (ventilation fan casing) is grounded, the DC motor shown in any of the first to third embodiments is simply mounted on the ventilation fan. Then, the grounding process for automatically connecting the circuit ground of the circuit board 10 to the ground (ground) is performed. As a result, the DC motor is mounted so as to ensure stable filter characteristics, so that the DC motor can be operated with less noise.

  And since the earth lead wire is not used for the connection between the circuit ground and the earth (ground) of the mounted DC motor, the cost of the earth lead wire can be reduced. In addition, since it is not necessary to change the length of the ground lead wire and the routing for each type of ventilation fan, standardization can be easily performed, and the cost can be reduced.

  In the first to fourth embodiments, the DC motor is a single-axis motor in which the shaft is extended from the motor frame side. However, the contents described in this embodiment are that the shaft is divided into the motor frame side and the motor bracket side. Needless to say, the present invention can be similarly applied to a double-axis motor that is extended from both sides.

  As described above, the DC motor according to the present invention holds the ground side of the Y capacitor at a low impedance only by fixing the outer frame housing incorporating all of the control circuits including the noise filter to the mounting target device. It is useful as a DC motor with a built-in control circuit that can reliably perform grounding.

  The ventilation fan according to the present invention is useful as a ventilation fan in which the DC motor of the present invention is mounted so as to ensure stable filter characteristics, and the cost can be reduced by standardization in parallel with the noise reduction of the DC motor.

1a, 1b, 1c DC motor 2 Motor frame 3 Motor bracket 5 Stator core 5a Core back 5b Iron core 5c Stator winding 6 Rotor 8 Shaft 10 Circuit board 11 AC input connector 12 Connector part 13 Filter circuit 14 Power supply circuit 14a Rectification circuit 14b For smoothing Capacitor 14c Switching power supply 15 Inverter circuit 15a Drive circuit 15b Switching circuit 16 Coil pin 17 Earth pin 18 Magnetic pole position sensor 22 Earth guide 24 Earth connection piece 30 Ventilation fan 31 Fan 32 Ventilation fan body 34 Power supply terminal block 35 Earth connection terminal Cx X capacitor Cy1, Cy2 Y Capacitor L Common mode choke coil

Claims (2)

An outer frame housing composed of a bottomed cylindrical metal motor frame that houses a motor portion including a stator and a rotor, and a metal motor bracket that closes an opening end of the motor frame;
A filter circuit configured by a noise filter; a power supply circuit that converts an AC power input through the filter circuit into a DC power; and a DC voltage output from the power circuit based on a PWM drive signal to switch the stator a control circuit and an inverter circuit for outputting a motor driving voltage applied to the stator windings been mounted, the circuit board arranged in said motor frame,
A DC motor in which the motor part and the circuit board are accommodated in the outer frame housing ,
A terminal member having one end connected to the circuit ground of the circuit board to which the ground side of the Y capacitor of the noise filter is connected by solder and the other end being press-fitted and fixed to the stator core; A DC motor, wherein the outer frame casing is connected with low impedance. A ventilation fan on which the DC motor according to claim 1 is mounted,
The outer frame casing of the DC motor is fixed to a ventilation fan casing that is grounded and connected to the ground.

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