This application claims the benefit of priority to Japanese Patent Application No. 2017-023490 filed on Feb. 10, 2017. The entire contents of this application are hereby incorporated herein by reference.
The present invention relates to a motor and electrical equipment.
Home appliances, such as a hair dryer, are connected to a source of domestic AC power. Accordingly, a motor mounted in the home appliance includes a board having a power conversion device mounted thereon and a board having a drive circuit mounted thereon. The power conversion device converts the power supplied from the power source to a DC current. The drive circuit supplies the power to the stator and rotationally drives the rotor.
For example, according to Japanese Unexamined Patent Application Publication No. 10-322973, a power module and a printed circuit board is provided so as to be arranged in the axial direction of the rotary shaft. The power module constitutes a power circuit of an inverter device serving as a power conversion device. The printed circuit board has electronic components mounted thereon. The electronic components constitute circuits other than the power circuit (for example, a drive circuit and a DC power supply circuit).
However, in the electric motor described in Japanese Unexamined Patent Application Publication No. 10-322973, a board having the power module mounted thereon is provided separately from the printed circuit board. Thus, the number of members increases, and the manufacturing cost of the motor increases. In addition, the size of the parts used in the DC power supply circuit (especially, electrolytic capacitors) is relatively large. Consequently, when a part is mounted on a surface of the print circuit board facing the stator side in the axial direction of the rotary shaft, it is necessary to dispose the printed circuit board at a position sufficiently away from the stator. For this reason, a bracket for accommodating the printed circuit board tends to increase in size. In particular, the size in the axial direction increases and, thus, the strength of the bracket that holds the printed circuit board may become insufficient. In addition, if the printed circuit board is away from the stator, breaking of a lead wire that electrically connects the circuit formed on the printed circuit board to the coil of the stator easily occurs.
According to the present invention, an exemplary motor includes a rotor including a rotary shaft that extends in the vertical direction, a stator that faces the rotor, a bearing for supporting the rotary shaft for rotation, a bearing holder for holding the bearing, a bracket for holding the bearing holder, and a circuit board having electronic components mounted thereon. The electronic components include a converter, an inverter, and a detection unit. The detection unit detects the rotation angle of the rotor on the basis of an induced voltage generated in the stator due to rotation of the rotor. The bracket includes a holding member that holds the lower end of the bearing holder. The circuit board is disposed under the holding member in the axial direction. The electronic components are disposed on the lower surface of the circuit board.
The exemplary motor according to the present invention can reduce the size of the motor and increases the reliability of a product including the motor.
The above and other elements, features, steps, characteristics and advantages of the present discloser will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings.
Exemplary embodiments of the present invention are described below with reference to the accompanying drawings. As used herein, in regard to a motor 100, the direction in which the rotary shaft of a rotor 1 (refer to a shaft 11 in
The radial direction of the shaft 11 is simply referred to as a “radial direction”, and the circumferential direction around the shaft 11 is simply referred to as “circumferential direction”. In addition, in the radial direction, the direction extending towards the shaft 11 is simply referred to as an “inward” direction, and the direction extending away from the shaft 11 is simply referred to as an “outward” direction. Furthermore, among the surfaces of each of the constituent elements, the side surface facing in the inward radial direction is referred to as an “inside surface”, and the side surface facing in the outward radial direction is referred to as an “outside surface”.
In regard to an apparatus or a device including the motor 100, the direction of the air flow sent out by an air blowing device 200 is referred to as “air flow direction”. In addition, in the air flow direction, the direction from the upstream to downstream is simply referred to as a “forward” direction, and the direction from the downstream to upstream is simply referred to as a “backward” direction.
The directions and surfaces described above do not indicate the positional relationship and the directions when the constituent elements are incorporated into an actual device.
According to the present embodiment, as illustrated in
The motor 100 is a drive unit that rotationally drives the impeller 101. The motor 100 is mounted in electrical equipment, such as a dryer 300 (refer to
As illustrated in
The rotor 1 is the rotor of the motor 100. The rotor 1 has the shaft 11, a rotor holder 12, and a magnet 13. The shaft 11 is a rotary shaft extending in both upward and downward axial directions. The rotor holder 12 is a member that holds the magnet 13 and is rotatable together with the shaft 11 and the impeller 101. The magnet 13 faces the stator 2.
The rotor holder 12 accommodates the rotor 1, the stator 2, and the bearing holder 4. The rotor holder 12 has a plate portion 121 and a cylindrical portion 122. The plate portion 121 is a disk-shaped member extending in an outward radial direction. The cylindrical portion 122 is a cylindrical member extending from the circumferential edge of the plate portion 121 in the axially downward direction. The peripheral wall member 101b of the impeller 101 is attached to the cylindrical portion 122 so as to be located radially outwardly of the cylindrical portion 122. The magnet 13 is held on the inside surface of the cylindrical portion 122.
The stator 2 is an armature of the motor 100. The stator 2 is held on the outside surface of the bearing holder 4. The stator 2 faces the rotor 1 and drives the rotor 1. The stator 2 includes a stator core 21, a plurality of coil portions 22, and an insulator 23.
The stator core 21 is a laminated steel plate in which electromagnetic steel plates are stacked in the axial direction. The stator core 21 is provided radially outwardly of the bearing holder 4 and radially inwardly of the magnet 13.
As illustrated in
The insulator 23 is an insulating member made of, for example, a resin material. The insulator 23 covers the stator core 21. The insulator 23 electrically insulates the stator core 21 from the coil portion 22. In addition, the insulator 23 has a support member 3 for supporting the wire wrapping pin 6. The support member 3 protrudes from the lower end of the insulator 23 toward the circuit board 7. The support member 3 has terminal supporting portion 31 and a connection portion 32. The terminal supporting portion 31 supports one of the wire wrapping pins 6. The connection portion 32 connects the adjacent terminal supporting portions 31 with each other (refer to, for example,
The bearing holder 4 is a metal bearing holding portion for holding the bearings 41 and 42. The bearing holder 4 is provided radially outward of the shaft 11 and radially inward of the stator 2. The bearings 41 and 42 are bearings which support the shaft 11 for rotation. For example, ball bearings or sleeve bearings are used as the bearings 41 and 42.
The bearing holder 4 has a cylindrical portion 4a extending in the axial direction and a rectangular plate portion 4b. The bearings 41 and 42 are held inside the cylindrical portion 4a. The plate portion 4b extends radially outward from the lower circumference of the cylindrical portion 4a. In the axial direction, the position of the lower surface of part of the plate portion 4b close to the cylindrical portion 4a is the same as the position of the lower surface of the bracket 5. In addition, the upper surface and the lower surface of both end portions of the plate portion 4b in the long direction are clamped by the bracket 5. In this way, the bearing holder 4 is held by the bracket 5. According to the present embodiment, the plate portion 4b and the cylindrical portion 4a are separate members, but may be a single member. That is, the plate portion 4b may extend radially outward from the lower end of the cylindrical portion 4a.
The bracket 5 holds the bearing holder 4. As illustrated in
The cylindrical member 51 is provided radially outwardly of the rotor holder 12 and the peripheral wall member 101b of the impeller 101. The cylindrical member 51 accommodates the lower portions of the stator 2 and the bearing holder 4. The pair of motor fixing members 53 is provided on the outside surface of the cylindrical member 51. In addition, the three board supporting portions 54 and the two hook members 55 are provided at the lower end of the cylindrical member 51 in the axial direction of the cylindrical member 51.
The holding member 52 holds the plate portion 4b. The holding member 52 has a portion extending in the long direction and a portion extending in the short direction. According to the present embodiment, the holding member 52 is a rectangular plate member. However, the holding member 52 is not limited to this example. The holding member 52 may have another shape, such as an oval shape. In a plan view as viewed from the axial direction, both ends in the long direction of the holding member 52 are joined to the cylindrical member 51 at two points where the pair of motor fixing members 53 are joined to the cylindrical member 51.
As illustrated in
The pair of motor fixing members 53 is attached to the electrical equipment having the air blowing device 200 mounted thereon (for example, the dryer 300 described below). The motor 100 is fixed to the electrical equipment through the attachment of the pair of motor fixing members 53. In the plan view as viewed from the axial direction, the two motor fixing members 53 are respectively joined to the cylindrical member 51 at two points of the circumferential edge of the lower end of the cylindrical member 51, where the two points are across from each other with the shaft 11 therebetween.
In the plan view as viewed from the axial direction, the board supporting portions 54 are provided on the circumferential edge of the lower end of the cylindrical member 51 at three positions. Each of the board supporting portions 54 has a stopper portion 541 and a pillar portion 542 (refer to
In the plan view as viewed from the axial direction, the hook members 55 are provided on the circumferential edge of the lower end of the cylindrical member 51 at two positions. Preferably, the hook members 55 are provided at two positions across from each other with the shaft 11 therebetween. Each of the hook members 55 has an extension portion 551 and a claw portion 552 (refer to
The bracket 5 is formed by injection molding using a resin material, for example. The holding member 52 is the same resin member as the cylindrical member 51, the motor fixing member 53, the board supporting portion 54, and the hook member 55. In addition, the holding member 52 is provided around the plate portion 4b (in particular, both end portions in the long direction) of the bearing holder 4. Consequently, the number of parts and the assembling steps can be reduced more than in the case where the holding member 52 is a member different from the cylindrical member 51, the motor fixing member 53, the board supporting portion 54, and the hook member 55.
In the plan view as viewed from the axial direction, a portion of the holding member 52 that extends in the long direction is parallel to, for example, a line segment extending between the middle of a portion of the circumferential edge of the lower end of the cylindrical member 51 to which one of the motor fixing members 53 is joined and the middle of a portion to which the other motor fixing member 53 is joined. That is, in the plan view as viewed from the axial direction, both ends of the portion of the holding member 52 extending in the long direction are respectively joined to the cylindrical member 51 at the above-mentioned two positions. As compared with a holding member joined to the entire circumference of the cylindrical member 51, the holding member 52 joined to the cylindrical member 51 at only the above-mentioned two positions of the cylindrical member 51 more easily dissipates vibration transferred to the bracket 5. For this reason, as compared with a holding member joined to the entire circumference of the cylindrical member 51, the holding member 52 joined to the cylindrical member 51 at only the above-mentioned two positions of the cylindrical member 51 can reduce the eigenvalue (the vibration frequency) generated in the bracket 5. In addition, the mounting strength of the motor 100 attached to the electrical equipment can be increased.
The circuit board 7 is, for example, a disk-shaped board made of a resin material, such as epoxy. The circuit board 7 is disposed at a position away from the holding member 52 in the downward axial direction. For example, as illustrated in
As illustrated in
The position detection circuit is a detection unit that detects the position (that is, the rotation angle) of the rotor 1 on the basis of the induced voltages generated in the coil portions 22 of the stator 2 due to the rotation of the rotor 1. Note that the induced voltages are voltages generated in the coil portions 22 by the magnetic force of the magnet 13 when the rotor 1 rotates. For example, the position detection circuit detects the induced voltage generated in each of the coil portions 22 and detects the zero cross of the detected voltage. That is, the position detection circuit further detects the time at which the detected voltage exceeds 0 [V] and the tendency of the voltage increase/decrease at this time. Thereafter, the position detection circuit detects the rotation angle of the rotor on the basis of the result of detection.
By setting the circuit board 7 below the holding member 52 in the axial direction, the need for setting a circuit board having electronic components mounted thereon between the stator 2 and the bracket 5 is eliminated. Thus, the size of the motor 100 can be reduced.
If the electronic components 71 are mounted on the lower surface of the circuit board 7, the shortest distance between the stator 2 and the circuit board 7 can be made shorter than when the electronic components 71 are mounted on the upper surface of the circuit board 7. In addition, even when an element having a relatively large size in the axial direction (e.g., the electrolytic capacitor 71a used in, in particular, the AC/DC converter) is mounted on the circuit board 7, the shortest distance between the stator 2 and the circuit board 7 need not be increased. In this way, the occurrence of breaking of a wire (in particular, the lead wire 221) between the stator 2 and the circuit board 7 can be reduced or prevented.
The electronic components 71 including, for example, an AC/DC converter, an inverter, a control circuit, and a position detection circuit are mounted on the same circuit board 7. In this manner, the number of parts (for example, the total number of circuit boards 7) can be reduced more than in a motor using a plurality of circuit boards and, thus, the manufacturing cost can be reduced.
A specific structure of the support member 3 is described below.
The support member 3 is a support member for supporting the wire wrapping pins 6. The support member 3 protrudes from the lower end of the insulator 23. The wire wrapping pins 6 are stably supported by the support member 3. As a result, the occurrence of breaking of the wires (in particular, the lead wire 221) between the coil portion 22 and the circuit board 7 due to the vibration of the motor 100 can be reduced or prevented more effectively.
The support member 3 is disposed in the connection opening 521 in a plan view as viewed from the axial direction (refer to
The support member 3 has three terminal supporting portions 31 and two connection portions 32. Note that the present invention is not limited to this example, and the number of the terminal supporting portions 31 may be any plural number other than three. Each of the terminal supporting portions 31 is a member for supporting the wire wrapping pin 6 and protrudes from the insulator 23 toward the circuit board 7. Each of the connection portions 32 connects the adjacent terminal supporting portions 31. In the radial direction, the radial width of the connection portion 32 is smaller than the radial width of the terminal supporting portion 31. As a result, in a plan view as viewed from the axial direction, the inside surface of the connection portion 32 forms a recess 33 together with the inside surfaces of the two adjacent terminal supporting portions 31, as illustrated in
In the holding member 52, the first protrusions 522 and the second protrusions 523 are provided on the circumferential edge of the connection opening 521. The first protrusions 522 protrude from the circumferential edge of the connection opening 521 in the outward radial direction and are in contact with the support member 3. The second protrusions 523 protrude from the circumferential edge of the connection opening 521 in the outward radial direction and are in contact with the support member 3. More specifically, as illustrated in
In this manner, the displacement of the support member 3 in both the inward radial direction and outward radial direction is suppressed. Consequently, a decrease in the strength of the support member 3 due to the vibration of the motor 100 can be reduced or prevented. In addition, the vibration of the motor 100 transferred from the holding member 52 via the first protrusions 522 and the second protrusions 523 can be reduced by the connection portion 32 and, thus, the vibration is less likely to be transferred to the terminal supporting portion 31. As a result, a decrease in the strength of the wire (in particular, the lead wire 221) between the coil portion 22 and the circuit board 7 due to the vibration of the wire wrapping pins 6 can be reduced.
The holding member 52 having the first protrusions 522 and the second protrusions 523 is a resin member. Consequently, even when the first protrusions 522 and the second protrusions 523 push the support member 3 due to the vibration of the motor 100, the force that pushes the support member 3 is reduced due to the elasticity of the holding member 52 having the first protrusions 522 and the second protrusions 523. As a result, a decrease in the strength of the support member 3 due to the vibration of the motor 100 can be reduced or prevented.
It is desirable that in a plan view as viewed from the axial direction, the first protrusions 522 and the second protrusions 523 be in point contact with the inside surface and the outside surface of the connection portion 32, respectively. In addition, in a plan view as viewed from the axial direction, the points of the inside surface of the connection portion 32 with which the first protrusion 522 is in contact may be single, and the points of the outside surface of the connection portion 32 with which the second protrusion 523 is in contact may be single. However, it is more desirable that the points be plural. For example, in
The dryer 300 is described below. The dryer 300 is an example of application of the electrical equipment having the air blowing device 200 including the above-described motor 100 according to the present embodiment.
Subsequently, the dryer 300 is electrical equipment for blowing out hot air. The dryer 300 rotates the impeller 101 of the air blowing device 200 by using the rotary drive of the motor 100 and sends an air flow frontward in the air blowing direction. The dryer 300 heats the air flow sent in the forward air blowing direction with a heater and discharges the heated air flow (that is, hot air) to the outside. The dryer 300 is used as, for example, a hairdryer for home or business use that dries hair. However, the dryer according to the present invention may be a dryer for drying or heating something other than hair, such as an industrial dryer.
As illustrated in
The dryer housing 301 is a casing of the dryer 300. The dryer housing 301 includes an air inlet 301a, an air outlet 301b, and an internal space 301c. The air inlet 301a is disposed in a rear portion of the dryer housing 301 in the air blowing direction. The air outlet 301b is provided in a front portion of the dryer housing 301 in the air blowing direction. The air inlet 301a and the air outlet 301b communicate with the internal space 301c of the dryer housing 301. The air blowing device 200 using the motor 100, the flow rectifier member, and the heater are disposed in the internal space 301c.
The impeller 101 of the air blowing device 200 is disposed in the rear portion in the air blowing direction, and the motor 100 is disposed in the front portion in the air blowing direction. The axial direction of the air blowing device 200 is parallel to the air blowing direction of the dryer 300. The upward axial direction corresponds to a direction opposite to the air blowing direction. The downward axial direction corresponds to the air blowing direction.
The flow rectifier member has a plurality of stator vanes (not illustrated) arranged in the circumferential direction of the motor. Each of the stator vanes is provided radially outward of the motor 100, that is, between the motor 100 and the dryer housing 301.
The heater is provided between the air blowing device 200 and the air outlet 301b. The heater is a heating member for heating an air flow. The heater has a heating wire, such as a nichrome wire, which generates heat by passing an electric current therethrough.
When the power switch (not illustrated) of the dryer 300 is switched on, the air blowing device 200 is activated. By rotation of the impeller 101, the air blowing device 200 generates an air flow flowing from the outside of the dryer housing 301 into the internal space 301c through the air inlet 301a. The air flow flowing into the internal space 301c is sent from the air blowing device 200 in the outward radial direction by the rotation of the impeller 101. The air flow is guided to between the plurality of stator vanes by the inner surface of the internal space 301c and is sent toward the heater. The air flow flowing around the heater is heated by the heater. Thereafter, the heated air flow is blown out from the air outlet 301b.
The embodiments of the present invention have been described above. It should be noted that the scope of the present invention is not limited to the above-described embodiments. The present invention can be implemented with various modifications without departing from the spirit and scope of the invention. Furthermore, the above-described embodiments can be combined in any way as appropriate.
For example, while the above embodiment has been described with reference to the motor 100 of an outer rotor type, the type of motor is not limited to this example. The motor may be of an inner rotor type.
In addition to the dryer (refer to
Features of the above-described preferred embodiments and the modifications thereof may be combined appropriately as long as no conflict arises.
While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.
Number | Date | Country | Kind |
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2017-023490 | Feb 2017 | JP | national |