JP2018161022A - DC motor and ventilator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a DC motor with built-in circuit that isolates a motor part including a stator and a rotor from a circuit board housing part that houses a circuit board on which a control circuit is mounted and improves the strength of a rotor bearing.SOLUTION: The DC motor includes: a motor portion including a stator 7 and a rotor 6; a bottomed cylindrical motor frame 2 for housing the motor portion; a circuit board 10 on which a control circuit is mounted; a motor cover 4 that covers the circuit board 10 and forms a circuit board housing part; and a metallic motor bracket 3 for isolating the motor portion and the circuit board housing part from each other between the motor frame 2 and the motor cover 4.SELECTED DRAWING: Figure 1

Description

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

Motors that are often used in electrical appliances are moving from AC (alternating current) motors to DC (direct current) motors. A motor that uses a permanent magnet as a rotor and is driven by an inverter is installed in almost all products in air conditioners and refrigerators.
In most conventional DC motors, a DC power supply is connected from the outside of the motor. An inverter circuit for applying a voltage to the motor stator is mounted inside the motor, and a control signal is sent from the external control circuit to the motor. Input to control the motor.
In addition, when a DC motor is used in a conventional product such as a ventilation fan that does not have a control circuit or a power supply circuit, a motor in which a control circuit and a power supply circuit are mounted inside the motor is used.

  DC motors used in such ventilation fans use a structure in which the motor parts such as the rotor and the stator are separated from the circuit parts such as the control circuit and the power circuit depending on the usage conditions such as the bathroom and the bathroom. It is trying not to affect.

Further, the DC motor needs to detect the position of the rotor with a sensor (refer to the above-mentioned magnetic pole position sensor) and apply it to the stator winding to control the voltage phase.
For this reason, it is necessary to arrange a magnetic pole position sensor circuit near the rotor separately from the control circuit. Alternatively, when a magnetic pole position sensor is mounted on the control circuit, it is necessary to bring the control board close to the rotor to such a distance that the magnetic pole position sensor of the control circuit can detect the rotor magnetic flux as a magnetic pole switching signal of the rotor.
For this reason, a part that uses a resin material that transmits magnetic flux as a part for separating the motor part and the circuit part is employed.

JP2011-250545A

  In the structure of Patent Document 1, a resin material is used for a motor bracket that holds a bearing of a rotor and closes an opening end of a motor frame as a component for isolating the circuit board housing portion from the motor portion. This structure requires a resin material, which adds to the resin molding process, and even if the cost of the material and processing increases, there is a limit to the strength of the resin, which hinders a cheap and robust motor structure. It will be.

  In addition, when the bearing holding portion is made of resin, there is a problem that the life is shortened or the motor is not suitable for a device having a large blade because the strength is limited.

  The present invention has been made in view of the above, and reliably retains the bearings of the rotor, isolates the motor portion such as the rotor and the stator from the circuit board housing portion, and provides an inexpensive and robust DC motor. The purpose is to configure.

  A motor part including a stator and a rotor, a bottomed cylindrical motor frame for housing the motor part, a circuit board on which a control circuit for controlling the rotation speed of the rotor is mounted, and a circuit board that covers the circuit board A motor cover that forms a storage portion, and a metal motor bracket that is disposed between the motor frame and the motor cover and isolates the motor portion from the circuit board storage portion.

According to the present invention, the motor bracket is formed by constricting a material such as a metal sheet metal instead of a motor bracket formed by molding a resin. There is no need to prepare. Further, since the bearing support force is increased, a large blade can be used, which leads to an increase in the strength of the structure.
Further, the conventional structural restriction that the magnetic pole position sensor and the circuit must be arranged without being separated is eliminated, and the degree of freedom in structural design is greatly improved.

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 covers the opening of the motor frame 2, and a motor cover 4 that covers the circuit board 10. Has been. The motor frame 2, the motor bracket 3, and the motor cover 4 are provided with flanges 2a, 3a, and 4a that can be screwed to each other 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 circuit board housing part on the upper part of 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 7 and a rotor 6 are arranged in the motor partial storage portion.
The stator 7 has three-phase (U-phase, V-phase, and W-phase) stator windings 7a on the inner periphery of the motor frame 2 that protrudes from the inner periphery of the cylindrical yoke at intervals of 120 degrees. It is placed in close contact with the surface.

  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 circuit board 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.

  One end of the coil pin 16 is fixed to a resin layer (not shown) that covers the circuit case 5 side of the stator 7. 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 and the housing 4, and the other end is connected to the circuit board 10. Above, it is pattern-connected to the corresponding output terminal of the switching circuit 15b in the inverter circuit 15.

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.

  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 a magnetic pole position sensorless drive in which a magnetic pole position sensor such as a Hall IC is deleted, and has a magnetic pole position estimating means for estimating the magnetic pole position of the rotor. The magnetic pole position estimating means estimates the position of the rotor 6 from the current flowing through the stator winding 7a and the motor constant, and generates a PWM signal so that the desired stator winding 7a can be energized. As a result, the rotor 6 rotates and the shaft 8 rotates.

  In FIG. 1, a motor bracket 3 is provided at the opening end of the motor frame 2. The motor frame 2, the motor bracket 3, and the motor cover 4 are each made of a metal material. The motor bracket 3 is formed by a sheet metal drawing die or the like, for example, and a holding portion for holding the rotor bearing 9a is provided at the center.

Thus, by providing the motor bracket 3, the motor part and the circuit board 10 accommodated in the circuit board accommodating part can be easily isolated. Therefore, it is possible to improve the reliability without giving the circuit board 10 moisture or the like of the room where the ventilation fan is used. In addition, since the strength of the holding portion of the bearing 9a can be improved, it can be used for a large device equipped with a large blade having a heavy weight, and the life of the motor can be extended.
Conventionally, when the magnetic pole position sensor is mounted, the magnet mounted on the rotor 6 protrudes more than the thickness of the rotor 6 in order to bring the end face of the magnet closer to the magnetic pole position sensor mounted on the control circuit. It was necessary to make it into a shape. However, there is no magnetic pole position sensor this time, and it is no longer necessary to bring the rotor magnet close to the magnetic pole position sensor. Therefore, the configuration of the rotor 6 is simplified, the magnet is only required to be the minimum length, and the motor is compact. Can be

Embodiment 2. FIG.
FIG. 3 is a cross-sectional view showing the 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. In FIG. 3, the position information of the rotor 6 is detected using the magnetic pole position sensor 40.
As shown in FIG. 3, the magnetic pole position sensor 40 is mounted on a sensor substrate 41. The sensor substrate 41 is fixed to the resin layer of the stator 7 inside the motor, and is connected to the circuit substrate 10 by sensor leads 43. A through hole 43 is provided in the motor bracket 3 and the circuit case 5, and the sensor lead 42 is connected through the through hole 43.

As described above, according to the second embodiment, since the magnetic pole position sensor 40 is used in the outer casing of the DC motor 1 and in the vicinity of the rotor 6, the position information of the rotor 6 can be accurately grasped. Further, since the motor bracket 3 and the through hole 43 of the circuit case 5 need only have a diameter that allows the sensor lead 42 to pass therethrough, the motor bracket 3 and the circuit board housing portion can be partitioned without greatly affecting the isolation. It is possible.
Further, since the magnetic pole position sensor 40 is disposed in the vicinity of the rotor 6, it is not necessary to bring the magnet of the rotor 6 close to the circuit board 10, and the size can be minimized, and the material cost can be reduced.

  Therefore, as in the first embodiment, the humidity of the room where the ventilation fan is used does not affect the circuit board 10, and the strength of the holding portion of the bearing 9a can be ensured, so that it is also adopted for large equipment. In addition, the life of the motor can be extended.

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 casing 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 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.

  As shown in FIG. 4, in the DC motor 1, the ventilation fan body 32 of the ventilation fan 30 and the flange 4 a of the motor cover 4 are fixed with screws 33. Although there are two screws 33 in FIG. 4, they are appropriately selected and tightened according to the size of the DC motor 1. In this structure, motor parts such as the motor frame 2, the rotor 6, and the stator 7 of the DC motor 1 are arranged in the ventilation fan body 32. On the other hand, the circuit board 10 of the circuit board housing portion built in the motor cover 4 is disposed outside the ventilation fan body 32.

  Here, the ventilation fan 30 is used for various purposes. For example, in residential applications, it is widely used in living rooms, kitchens, bathrooms, toilets, and the like. For this reason, the inside of the ventilation fan body 32 of the ventilation fan 30 varies greatly depending on the use environment, such as being exposed to high-temperature air containing oily smoke or water vapor in a residential kitchen, or being exposed to high-humidity air in a bathroom, for example.

  Therefore, although the motor part of the DC motor 1 inside the ventilation fan body 32 may be exposed to various environments in the house as described above, the circuit board 10 of the circuit board housing part built in the motor cover 4 is The motor bracket 3 can be isolated from the motor portion so as to obtain a substantially stable atmosphere.

As described above, according to the third embodiment, the circuit board 10 in the circuit board housing portion can be maintained in a relatively stable state without being influenced by the environment in which the ventilation fan 30 is used. 1 can be improved and the life can be extended. Further, since the motor bracket 3 is made of metal, the strength for holding the bearing 9a of the rotor 6 is improved, and heavy blades such as large blades and metal blades can be used. Will expand the use of.
Further, here, for example, the explanation was made for residential use, but the same applies to business use. Furthermore, since the DC motor 1 can be miniaturized, the ventilating fan 30 can be miniaturized, and the use of the ventilating fan 30 having a large air volume can be obtained with the size of the conventional ventilating fan body 32 to further expand its application. Is possible.

  In the first to third embodiments, the DC motor 1 is a single-axis motor in which the shaft is extended from the motor frame side. However, the contents described in this embodiment are the shafts on 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 is useful as a DC motor with a built-in control circuit because the motor portion and the circuit board portion can be separated by a strong metallic motor bracket.

  Moreover, the ventilation fan concerning this invention is mounted as the DC motor control circuit of the said invention is ensured so that the stable temperature-humidity environment can be ensured, and it is useful as a ventilation fan which can anticipate long-term reliability of a DC motor.

DESCRIPTION OF SYMBOLS 1 DC motor 2 Motor frame 3 Motor bracket 4 Motor cover 5 Circuit case 6 Rotor 7 Stator 7a Stator winding 8 Shaft 9a, 9b Bearing 10 Circuit board 11 AC input connector 13 Filter circuit 14 Power supply circuit 14a Rectifier circuit 14b Smooth Capacitor 14c Switching power supply 15 Inverter circuit 15a Drive circuit 15b Switching circuit 16 Coil pin 20 Current fuse 30 Ventilation fan 31 Fan 33 Screw 34 Power supply terminal block 32 Ventilation fan body 35 Ground connection terminal 36 Switch 37 AC power supply 38 Ground wire 40 Magnetic pole position sensor 41 Sensor Substrate 42 Sensor lead 43 Through hole Cx X capacitor Cy1, Cy2 Y capacitor L Common mode choke coil

Claims (4)

A motor part including a stator and a rotor;
A bottomed cylindrical motor frame that houses the motor portion;
A circuit board equipped with a control circuit for controlling the rotational speed of the rotor;
A motor cover that covers the circuit board and forms a circuit board housing portion;
A metal motor bracket disposed between the motor frame and the motor cover to isolate the motor portion and the circuit board housing;
A DC motor comprising:   2. The DC motor according to claim 1, wherein the control circuit includes magnetic pole position estimating means for estimating a magnetic pole position of the rotor.   2. The DC motor according to claim 1, wherein the stator includes a sensor board on which a magnetic pole position sensor for detecting a magnetic pole position of the rotor is mounted.   The ventilation fan carrying the DC motor in any one of Claims 1-3.

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