JP3650906B2 - Motor and electric power steering apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a motor including a plurality of brushes that slide on a commutator and a plurality of brush holders that hold the brushes inside and urge the commutator toward the commutator, and to use this motor for steering force. The present invention relates to an auxiliary electric power steering device.
[0002]
[Prior art]
An electric power steering device for a vehicle includes, for example, a torque sensor that detects a steering torque applied to an input shaft by a relative angular displacement between the input shaft and an output shaft that is coaxially connected to the input shaft via a torsion bar, and a torque sensor And a control unit that drives and controls the steering assist motor based on the detected torque, and assists the operation of the steering mechanism according to the rotation of the steering wheel by the rotation of the motor, and the driver's labor for steering It is configured to reduce the burden.
[0003]
The steering assist motor has a cylindrical stator fixed in the housing, a commutator and a rotor shaft, a rotor arranged rotatably in the stator, and attached in the housing. And a brush that slides on the commutator. The brush is connected to a power source such as a battery via a motor drive circuit, and is configured to supply current to the rotor via the brush and the commutator.
[0004]
FIG. 4 is an external view showing a brush holder for holding a brush of a conventional steering assist motor. The two brush holders 79 are fixed to the inside of a cylindrical brush holder frame 80 that is to be fitted in the motor housing, and each opening extends to the center of the brush holder frame 80 at a position approximately 90 degrees apart. Is directed. The brush holder 79 is a hollow cylindrical type with a bottom, and a majority of the brush 74 is fitted inside and held.
Supporting rods 80a for supporting each other are provided at the tip portions of the two brush holders 79.
[0005]
FIG. 5 is an enlarged cross-sectional view showing a state in which a brush and a brush holder of a conventional steering assist motor are installed. The brush holder 79 is supported by a brush holder frame 80 fitted in a bracket 81 (housing) of the motor. The brush holder 79 holds and holds the majority of the brush 74 inside, and the brush 74 is attached in the direction of the commutator 78 coaxially fitted to the rotor shaft 76 by a spring 73 provided at the bottom. It is fast. In the bottom corner of the brush holder 79, a hole 79a for allowing the wear powder 12 of the brush 74 in the brush holder 79 to escape to the outside is provided.
[0006]
[Problems to be solved by the invention]
In the motor as described above, when the abrasion powder 12 of the brush 74 due to sliding with the commutator 78 is accumulated between the brush 74 and the conductive bracket 81, the motor current is absorbed by the abrasion powder 12 of the brush 74. There is a problem that the electric power steering apparatus may not operate normally due to flow through other than the motor coil (leakage).
[0007]
In particular, the motor of the electric power steering apparatus is used for both left and right rotations, and is surrounded by a brush 74, a brush holder 79, a commutator 78 and a support bar 80a shown in FIG. The peripheral portion of the hole 79a between the brush holder 79 and the bracket 81 shown in FIG. 5 and the portion surrounded by the brush 74, the brush holder 79, the commutator 78 and the bracket 81 shown in FIG. In this structure, the wear powder 12 is concentrated and easily collected.
An object of the present invention is to provide a motor and an electric power steering apparatus that can solve the above-described problems.
[0008]
[Means for Solving the Problems and Effects of the Invention]
A motor according to a first aspect of the present invention includes a plurality of brushes that slide on a commutator, and a plurality of brushes that are juxtaposed around the commutator and that hold each brush inside and bias the commutator toward the commutator. In a motor including a holder and a housing in which the brush holder is fitted, a space for dispersing the abrasion powder of the brush generated by sliding with the commutator is provided between the adjacent brush holders and the brush. It is provided between the holder and the housing.
[0009]
In this motor, a plurality of brushes slide on the commutator, and a plurality of brush holders are juxtaposed around the commutator, and each brush is held inside and urged toward the commutator. Space for dispersing the abrasion powder of the brush generated by sliding with the commutator is provided between the adjacent brush holders and between the brush holder and the housing. Does not cause malfunction.
[0010]
A motor according to a second aspect of the present invention includes a plurality of brushes that slide on the commutator, a plurality of brush holders that hold each brush inside and bias the commutator toward the commutator, and fix the plurality of brush holders In a motor provided with a brush holder frame that engages and a housing in which the brush holder frame is fitted, a space for dispersing abrasion powder generated by sliding with the commutator is provided in the housing and the brush. It is provided by interposing an insulator between the holders.
[0011]
In this motor, a plurality of brushes slide on the commutator, and a plurality of brush holders hold the brushes inside and urge them toward the commutator. The brush holder frame fixes a plurality of brush holders, and the housing fits in the brush holder frame. Since a space for dispersing the abrasion powder of the brush generated by sliding with the commutator is provided by interposing an insulator between the housing and the brush holder, it is difficult for the abrasion powder to concentrate and collect. Since the insulator insulates the brush and the brush holder from the housing, malfunction due to electric leakage does not occur.
[0012]
According to a third aspect of the present invention, there is provided an electric power steering apparatus according to the first or second aspect of the present invention, a control unit that drives and controls the motor according to the steering of the steering means, and the rotational force of the motor as a steering mechanism. And a transmission means for transmitting.
[0013]
In this electric power steering apparatus, the control unit drives and controls the motor according to claim 1 or 2 according to the steering of the steering means, and the transmission means transmits the rotational force of the motor to the steering mechanism. Does not cause malfunction due to electric leakage.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments thereof.
FIG. 1 is a cross-sectional view showing a configuration of an embodiment of a motor and an electric power steering apparatus according to the present invention. However, for the motor 7, a cross section approximately 45 degrees is shown in order to show a cross section of the brush holder 23.
This electric power steering apparatus has a bar insertion hole 1a, and an upper end (right end in the figure) is inserted into a cylindrical input shaft 1 connected to a steering wheel (not shown) for steering and a bar insertion hole 1a. A torsion bar 3 whose upper end is coaxially connected to the upper end of the input shaft 1 via the dowel pin 2 and an output shaft 5 coaxially connected to the lower end (the left end in the figure) of the torsion bar 3 via the dowel pin 4. ing.
[0015]
The electric power steering apparatus is also provided with a steering assist motor 7 attached to a first housing 6 that accommodates the input shaft 1 and the output shaft 5, and is accommodated in the housing 6 and input by rotation of the steering wheel. A torque sensor 8 that detects the torque applied to the shaft 1 by a twist generated in the torsion bar 3; a control unit 9 that is connected to the torque sensor 8 and that controls the drive of the motor 7 based on the torque detected by the torque sensor 8; Transmission means 10 for transmitting the rotation of the motor 7 to the output shaft 5 is provided.
[0016]
The lower end of the output shaft 5 is a pinion provided with a pinion of a steering mechanism (not shown) having a rack shaft extending in the left-right direction at the front portion of the vehicle body and a pinion meshing with a middle portion of the rack shaft. It is connected to the upper end of the shaft.
A torque sensor 8 is connected to an input unit of the control unit 9 using a microprocessor, and a motor drive circuit 11 of the motor 7 is connected to an output unit of the control unit 9.
[0017]
The transmission means 10 is a hypoid gear having a small gear 10 a that is a hypoid pinion and a large gear 10 b that is a hypoid wheel. The small gear 10 a is integrally formed at the end of the rotor shaft 76 of the motor 7. . The large gear 10 b has a tooth around a conical portion on one side, and an inner peripheral surface is externally fitted to an intermediate portion of the output shaft 5.
[0018]
The motor 7 includes a cylindrical stator 71 fixed in a cylindrical second housing 70 detachably connected to the first housing 6 via a bracket 70a (motor housing); A rotor 72 rotatably arranged in the stator 71 and two brushes 74 attached to the bracket 70a via the respective brush holders 23 and sliding on a commutator 78 described later are provided. Are connected to a power source such as a battery via a motor drive circuit 11, and the motor drive circuit 11 is connected to the control unit 9.
[0019]
The rotor 72 has a rotor shaft 76 rotatably supported in the second housing 70 at both ends via respective bearings 75, and a drive winding 77 fixed to an intermediate portion of the rotor shaft 76. , And a commutator 78 that slides on the brush 74, and the commutator 78 is connected to the drive winding 77.
[0020]
The two brush holders 23 are fixed to the inside of the cylindrical brush holder frame 22 at positions separated by approximately 90 degrees so that the respective openings are directed to the center of the rotor shaft 76. The brush holder 23 fits and holds the majority of the brush 74 inside. The brush holder plate 20 is sandwiched between the brush holder frame 22 and the bracket 70a.
[0021]
FIG. 2 is an external view showing the brush holder 23. As described above, the two brush holders 23 are fixed to the bracket 70a on the inner side of the cylindrical brush holder frame 22 to be fitted with the brush holder plate 20 interposed therebetween, and are approximately 90 degrees apart. The openings are provided so that each opening is directed to the center of the brush holder frame 22. The brush holder 23 is a bottomed hollow cylindrical type, and a majority of the brush 74 slightly thinner than the inner diameter is fitted and held inside.
Since no support rod or the like is provided between the two brush holders 23 shown in D for supporting the brush holders 23, a wide space can be secured and the wear of the brush 74 caused by sliding with the commutator 78. Powder can be dispersed.
[0022]
FIG. 3 is an enlarged cross-sectional view showing the installation state of the brush 74 and the brush holder 23. The brush holder 23 is supported by a brush holder frame 22 fitted in a bracket 70a (housing) of the motor, holds the majority of the brush 74 by fitting it inside, and the brush 74 is held by a spring 73 provided at the bottom. , And biased toward the commutator 78 that is coaxially fitted to the rotor shaft 76.
[0023]
Between the brush holder 23 and the bracket 70a, the brush holder plate 20 having an L-shaped cross section, which is an insulator, is sandwiched as described above, and the space between the brush 74 and the bracket 70a as shown in E and F. The creepage distance is kept long. Therefore, the abrasion powder 12 of the brush 74 generated by sliding with the commutator 78 can be dispersed in the space. Moreover, since the brush holder plate 20 which is an insulator insulates between the brush 74 and the brush holder 23, and the bracket 70a, the electric leakage by the abrasion powder 12 of the brush 74 can be prevented.
[0024]
Hereinafter, operations of the motor and the electric power steering apparatus having such a configuration will be described.
In this electric power steering device, the steering torque applied to the steered wheels is generated by the relative angular displacement of the torque sensor 8 between the input shaft 1 and the output shaft 5 coaxially connected to the input shaft 1 via the torsion bar 3. To detect.
The control unit 9 drives and controls the steering assisting motor 7 based on the steering torque detected by the torque sensor 8. The rotation of the motor 7 is transmitted to the output shaft 5 by the transmission means 10, and the transmitted rotation is converted into a movement of the front wheels of the vehicle in the left-right direction by the steering mechanism. As described above, the operation of the steering mechanism according to the rotation of the steered wheels is assisted by the rotation of the motor, and the labor burden on the driver for steering is reduced.
[0025]
In the motor 7, a space surrounded by the brush 74, the brush holder 23, and the commutator 78 shown by D in FIG. 2, and a brush 74, the brush holder 23, the commutator 78, and the bracket 70a shown by F in FIG. Therefore, the wear powder 12 of the brush 74 generated by sliding with the commutator 78 can be dispersed, and leakage due to the wear powder 12 of the brush 74 can be prevented.
Further, as shown by E and F in FIG. 3, even if the abrasion powder 12 of the brush 74 is accumulated between the brush holder 23 and the bracket 70a, the brush holder plate 20 which is an insulator is not attached to the brush holder 23 and the bracket 70a. The insulation state between them can be maintained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a configuration of an embodiment of a motor and an electric power steering apparatus according to the present invention.
FIG. 2 is an external view showing a brush holder of a motor according to the present invention.
FIG. 3 is an enlarged cross-sectional view showing a mounting state of a brush and a brush holder of a motor according to the present invention.
FIG. 4 is an external view showing a brush holder for holding a brush of a conventional motor.
FIG. 5 is an enlarged cross-sectional view showing a conventional motor brush and brush holder installation state.
[Explanation of symbols]
7 Motor 9 Control unit 10 Transmission means 12 Brush abrasion powder 20 Brush holder plate (insulator)
22 Brush holder frame 23 Brush holder 70a Bracket (housing)
72 Rotor 73 Spring 74 Brush 78 Commutator

Claims (3)

A plurality of brushes that slide on the commutator, a plurality of brush holders that are arranged around the commutator, hold each brush inside thereof, and urge the brush toward the commutator, and the brush holder In a motor having a housing to be fitted,
A motor characterized in that spaces for dispersing the abrasion powder of the brush generated by sliding with the commutator are provided between the adjacent brush holders and between the brush holder and the housing. A plurality of brushes that slide on the commutator, a plurality of brush holders that hold each brush inside and urge toward the commutator, a brush holder frame that fixes the plurality of brush holders, and the brush In a motor comprising a housing that fits in a holder frame,
A motor provided with a space for dispersing abrasion powder generated by sliding with the commutator by interposing an insulator between the housing and the brush holder. 3. A motor according to claim 1, comprising: a control unit that drives and controls the motor according to steering of a steering unit; and a transmission unit that transmits a rotational force of the motor to a steering mechanism. Electric power steering device.

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