JP2018161021A - Dc motor and ventilation fan - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a control circuit built-in DC motor that can maintain a ground side of a Y-capacitor to a low impedance and perform grounding processing with certainty, by only fixing an outer frame housing that incorporates all of a control circuit including a noise filter to a mounting target device.SOLUTION: On a circuit board 10, a control circuit (a filter circuit 13, a power supply circuit 14, and an inverter circuit 15) is mounted. As a configuration for connecting between an outer frame housing, which is configured by a metal motor frame 2 and a metal motor bracket 3, and the circuit ground of the circuit board 10 by a low impedance, a circuit ground pattern of the circuit board connected with the ground side of a Y-capacitor in the filter circuit 13, and the metal motor bracket 3 are connected by a screw 12. Grounding processing is performed to the motor frame 2 that is a part of an outline housing via a mounting target device.SELECTED DRAWING: Figure 1

Description

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

  A control circuit for driving and controlling a DC motor includes a power circuit that converts AC power into DC power, and an inverter circuit that generates AC voltage to be applied to the stator winding of the DC motor from the converted DC power. However, both the switching power supply in the power supply circuit and the switching circuit in the inverter circuit 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).

JP2011-250545A

  However, in the above conventional technique, since the circuit board and the ground pin are joined by solder, solder cracks are generated due to vibration and aging deterioration during the operation of the DC motor, and the impedance of the joint portion is increased to deteriorate the filter characteristics. There is a fear.

  In addition, since the ground pin is press-fitted into and contacted with the stator core, heat from the stator winding and the iron core is transmitted to the circuit board, which may reduce the life of the electronic components and soldered parts on the circuit board. Furthermore, when the DC motor is driven by an inverter, noise generated from the DC motor may be propagated onto the circuit board and cause a malfunction of the circuit.

Therefore, in the conventional DC motor and ventilation fan, the circuit board has a structure that is susceptible to heat and noise, and it has been difficult to stably reduce noise over a long period of time. There is also a problem that cracks are likely to occur in the soldered part due to heat and vibration.

  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. It is an object of the present invention to obtain a DC motor with a built-in control circuit that can reliably perform grounding, the circuit board is hardly subject to heat and noise, and can stably suppress noise over a long period of time.

  In addition, the present invention is low in that the DC motor according to the present invention is mounted so as to ensure stable filter characteristics and reliability of the soldered portion, and the ground lead wire is eliminated in parallel with the noise reduction of the DC motor. The purpose is to obtain a ventilation fan that can be cost-effective.

  In order to achieve the above-described object, the present invention includes a motor part including a stator and a rotor, a bottomed cylindrical metal motor frame that houses the motor part, and a metal motor bracket that closes the opening end of the motor frame. An outer casing provided, a filter circuit configured by a noise filter, a power circuit that converts an AC power input through the filter circuit into a DC power, and a power circuit output the casing A circuit board having a control circuit including an inverter circuit that switches a DC voltage and outputs a motor driving voltage that is applied to a stator winding of a stator, and a DC motor having a grounding of a Y capacitor of a noise filter The circuit ground pattern of the circuit board to which the side is connected and the metal motor bracket are connected by a metal fastener To.

  According to the present invention, all of the control circuit including the noise filter is built in the outer casing of the DC motor, and a low impedance is provided between the ground side (circuit ground) of the Y capacitor and the ground (outer casing). Connected with. 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, since the ground side (circuit ground) of the Y capacitor and the ground (ground) are connected with screws without using solder, there is no risk of solder cracking due to vibration during the DC motor operation or aging. In addition, since the circuit ground is fixed to the motor bracket with screws, heat and noise from the stator windings and the iron core are difficult to propagate to the circuit board, and it is possible to suppress malfunctions and lifetime reduction of the circuit board. Further, since no earth lead wire is required, the cost of the earth lead wire can be reduced, and there is no need to change the length or routing of the earth lead wire for each model, and there is an effect that a standardized DC motor and ventilation fan can be 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 an arrangement configuration of the DC motor according to the second embodiment of the present invention. FIG. 4 is a schematic external configuration diagram of a ventilation fan according to Embodiment 3 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 casing of the DC motor 1 includes a bottomed cylindrical motor frame 2, a motor bracket 3 that is a cover that closes the opening of the motor frame 2, and a cover 4 that covers the circuit board 10. ing. The motor frame 2, the motor bracket 3, and the cover 4 are each made of metal, and flanges 2 a, 3 a, 4 a that can be screwed to each other are provided on the outer peripheral edge.

  The outer casing of the DC motor 1 is partitioned by a motor bracket 3 into a motor part housing part on the motor frame 2 side and a control circuit housing part above the motor bracket 3. The circuit case 5 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 bracket 3.

A stator core 7 and a rotor 6 are arranged in the motor partial storage portion.
The stator core 7 has three-phase (U-phase, V-phase, W-phase) stator windings 7a on the inner peripheral surface of the motor frame 2 on three iron cores protruding at 120 degree intervals on the inner periphery of the cylindrical yoke. They are placed in close contact.

  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 motor bracket 3 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 circuit case 5. 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 an AC input connector 11, a filter circuit 13, a power supply circuit 14, and an inverter circuit 15 provided on the motor bracket 3.

  The ground pattern portion arranged on the circuit board 10 has a hole in the board. By inserting a metal screw 12 into the hole and tightening the screw 12 to the motor bracket 3, the ground pattern and the motor bracket 3 are connected. Thus, the entire outer shell of the motor becomes conductive with the ground pattern.

Next, the control circuit mounted on the circuit board 10 will be specifically described.
In FIG. 2, an AC power source 37 (AC 100 V to AC 240 V) input to the control circuit is input to the power source circuit 14 via the fuse 20 and the filter circuit 13 and is converted into a DC power source required by the inverter circuit 15. The

  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, although the example in which the Y capacitors Cy1 and Cy2 are arranged on the power supply circuit side of the common mode choke coil L has been shown, there are cases where they are arranged on the power input side of the common mode choke coil L.

  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 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 or DC 280V) 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 7a.

  The drive circuit 15a generates a PWM signal for driving on and off the six switching elements in the switching circuit 15b. In this system, the DC motor is driven by sensorless driving in which a magnetic pole position sensor such as a Hall IC is deleted, and the position of the rotor 6 is estimated from the back electromotive voltage generated from the stator winding 7a when the switching element is turned on / off. Then, a PWM signal is generated so that a desired stator winding 7a 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 Y capacitor in the filter circuit 13 → grounding pattern on the board → screw 12 → motor frame 3. It flows along the route. When the motor frame 2 that is a part of the outer 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 built in the outer casing of the DC motor 1, and the outer casing (the motor bracket 3) and the circuit ground are more reliably connected. The connection can be fixed, and simply by incorporating the DC motor 1 into the mounting target device, 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.

Therefore, the control circuit built-in type DC motor 1 having an excellent noise reduction effect can be obtained. In addition, since the ground pattern is connected by screw tightening without using solder, there is no risk of solder cracking due to vibration or aging deterioration, and a stable noise suppression effect can be obtained in the long term. In addition, since the circuit ground is fixed to the motor frame with screws, heat and noise from the stator winding 7a and the iron core are difficult to propagate to the circuit board, and it is possible to suppress malfunctions and lifetime reduction of the circuit board. .
Furthermore, since the earth lead wire for connecting the earth side (circuit earth) of the Y capacitor and the earth (ground) is not necessary, the cost of the earth lead wire can be reduced.
In FIG. 1, the circuit board 10 is arranged between the motor bracket 3 and the cover 4. However, the present invention is not limited to this. The same applies.

Embodiment 2. FIG.
FIG. 3 is a cross-sectional view showing an arrangement configuration of the DC motor 1 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. A metal nut 16 is press-fitted into the motor bracket 3, and the ground pattern and the motor outer shell are connected with low impedance by tightening the screw 12 to the ground pattern portion disposed on the circuit board 10.

  As described above, according to the second embodiment, all of the control circuit including the noise filter is built in the outer casing of the DC motor 1, and the outer casing (the motor bracket 3) and the circuit ground are more reliably connected. The connection can be fixed, and simply by incorporating the DC motor 1 into the mounting target device, 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.

  Therefore, as in the first embodiment, the control circuit built-in type DC motor 1 having an excellent noise reduction effect can be obtained. Since the ground pattern is connected by screw tightening without using solder, there is no fear of solder cracks due to vibration or aging deterioration, and a stable noise suppression effect can be obtained over a long period of time. In addition, since the circuit ground is fixed to the motor frame 2 with the screws 12, heat and noise from the stator winding 7a and the iron core are not easily transmitted to the circuit board, and it is possible to suppress malfunctions and lifetime reduction of the circuit board. It is. Furthermore, since the earth lead wire for connecting the earth side (circuit earth) of the Y capacitor and the earth (ground) is not necessary, the cost of the earth lead wire can be reduced.

Embodiment 3 FIG.
FIG. 4 is a schematic external configuration diagram of the ventilation fan according to the first embodiment of the present invention. In FIG. 4, the ventilation fan 30 according to the first embodiment is mounted with the DC motor 1 described in the first embodiment. The DC motor 1 described in the second embodiment is also mounted on the ventilation fan 30 in the manner shown in FIG.

  The DC motor 1 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 terminal block 35.

  The AC input connector 11 of the DC motor 1 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 1 is energized / interrupted by turning on / off the switch 36. When the switch 36 is turned on and the DC motor 1 is energized, the fan 31 connected to the shaft 8 of the DC motor 1 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 is screwed and fixed to the ventilation fan body 32, the outer casing of the DC motor 1 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 1 to ventilate the room is DC It flows along the route of the outer casing of the motor 1 → the ground terminal block 35 of the ventilation fan body 32 → the ground wire 38 → the ground (ground).

  As described above, according to the third embodiment, since the ventilation fan body (ventilation fan casing) 32 is grounded, the DC motor 1 shown in any of the first and second embodiments is mounted on the ventilation fan 30. By simply doing this, 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 1 is mounted so as to ensure stable filter characteristics, so that the DC motor 1 can be operated with less noise.

  And since the ground lead wire is not used for the connection between the circuit ground and ground (ground) of the mounted DC motor 1, the cost of the ground 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. Since the ground pattern is connected by screw tightening without using solder, there is no fear of solder cracks due to vibration or aging deterioration, and a stable noise suppression effect can be obtained over a long period of time. In addition, since the circuit ground is fixed to the motor frame 2 with the screws 12, heat and noise from the stator winding 7a and the iron core are not easily transmitted to the circuit board, and it is possible to suppress malfunctions and lifetime reduction of the circuit board. It is.

In the first to third embodiments, the DC motor 1 is a single-axis motor in which the shaft 8 is extended from the motor frame side. However, the content described in this embodiment is that the shaft 8 is connected to the motor frame 2 side. Needless to say, the present invention can be similarly applied to a double-axis motor that is extended from both sides of the motor bracket 3 side.
In this embodiment, the sensorless drive is described as a premise. However, the motor bracket 3 is notched or the motor bracket 3 is integrally formed of resin and metal so that a DC using a sensor such as a Hall IC is used. The present invention can also be applied to a motor drive device.
The DC motor of the present invention may be brushless or with a brush. Needless to say, the motor drive voltage can be applied not only to a high voltage drive of DC 140 V or DC 280 V but also to a low voltage drive configuration of 50 V or less.

  As described above, the DC motor according to the present invention holds the grounding side of the Y capacitor at a low impedance only by fixing the outer casing containing all of the control circuit 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.

  Further, 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 long-term reliability can be expected in parallel with the reduction in noise of the DC motor.

DESCRIPTION OF SYMBOLS 1 DC motor 2 Motor frame 3 Motor bracket 4 Cover 5 Circuit case 6 Rotor 7 Stator core 7a Stator winding 8 Shaft 9a, 9b Bearing 10 Circuit board 11 AC input connector 12 Screw 13 Filter circuit 14 Power supply circuit 14a Rectification circuit 14b Smoothing capacitor 14c Switching power supply 15 Inverter circuit 15a Drive circuit 15b Switching circuit 16 Nut 20 Fuse 30 Ventilation fan 31 Fan 32 Ventilation fan body 33 Screw 34 Power connection terminal block 35 Ground terminal block 36 Switch 37 AC power supply 38 Ground wire Cx X capacitor Cy1, Cy2 Y capacitor L Common mode choke coil

Claims (4)

An outer casing including a motor part including a stator and a rotor, a bottomed cylindrical metal motor frame that houses the motor part, and a metal motor bracket that is connected to the motor frame and closes an opening end of the motor frame. When,
A filter circuit configured by a noise filter, a power supply circuit that converts AC power input through the filter circuit into DC power, and a DC voltage output from the power circuit are switched inside the outer casing. A control circuit comprising: an inverter circuit that outputs a motor drive voltage applied to the stator winding of the stator;
A DC motor equipped with
A DC motor, wherein a circuit ground pattern of the circuit board to which a ground side of a Y capacitor of the noise filter is connected and the metal motor bracket are connected by a metal fastener.   The DC motor according to claim 1, wherein the metal fastener is a screw.   The DC motor according to claim 2, wherein a nut is fixed to the metal motor bracket, and a screw is fastened to the nut for fixing. A ventilation fan in which the DC motor according to claim 1 is mounted,
The outer casing of the DC motor is fixed to a ventilation fan casing that is grounded and connected to the ground.

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