JP2001231222A - Motor and electrical power steering apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor free from malfunction with a leakage current wherein friction powder of brush is not easily concentrated and reserved. SOLUTION: This motor comprises a plurality of brushes 74 sliding on a commutator 78, a plurality of brush holders 23 that are allocated in parallel at the circumference of the commutator 78 to hold therein each brush 74 to energize toward the commutator 78 and a housing (not shown) internally engaged with the brush holders. A space for dispersing the friction powder of the brush 74 generated with the sliding on the commutator 78 is provided between the adjacent brush holders 23 (D) and between the brush holder 23 and housing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor provided with a plurality of brushes sliding on a commutator, and a plurality of brush holders for holding the respective brushes inside and biasing the brushes toward the commutator. The present invention relates to an electric power steering device that assists a steering force using a motor.

[0002]

2. Description of the Related Art An electric power steering device for a vehicle, for example, detects a steering torque applied to an input shaft by a relative angular displacement between an input shaft and an output shaft coaxially connected to the input shaft via a torsion bar. A sensor for controlling the steering assist motor based on the torque detected by the torque sensor, and assisting the operation of the steering mechanism in accordance with the rotation of the steered wheels by the rotation of the motor. Is configured to reduce the labor burden on the driver.

[0003] The steering assist motor has a tubular stator fixed in a housing, a commutator and a rotor shaft.
A rotor rotatably arranged in the stator, and a brush mounted in the housing and sliding on the commutator, wherein the brush is connected to a power source such as a battery via a motor drive circuit, and the brush is And a current is supplied to the rotor via the commutator.

FIG. 4 is an external view showing a brush holder for holding a brush of a conventional steering assist motor. This 2
The two brush holders 79 are fixed inside a cylindrical brush holder frame 80 to be fitted into the motor housing, and each opening is directed toward the center of the brush holder frame 80 at a position separated by about 90 degrees. ing. The brush holder 79 is of a hollow cylindrical shape with a bottom, and holds the majority of the brush 74 by fitting it inside. A support rod 80a for mutually supporting the two brush holders 79 is provided at the distal ends of the two brush holders 79.
Is provided.

FIG. 5 is an enlarged sectional view showing the state of installation of the brushes and brush holders of a conventional steering assist motor. The brush holder 79 is provided with the motor bracket 8.
Brush holder frame 8 fitted in 1 (housing)
0 supported. The brush holder 79 holds the brush 74
The brush 74 is urged by a spring 73 provided at the bottom toward a commutator 78 coaxially fitted to the rotor shaft 76. At the bottom corner of the brush holder 79, there is provided a hole 79a for letting the abrasion powder 12 of the brush 74 in the brush holder 79 to the outside.

[0006]

In the motor as described above, the abrasion powder 1 of the brush 74 caused by the sliding with the commutator 78 is reduced.
2 accumulates between the brush 74 and the conductive bracket 81, the motor current is
This causes a problem that the electric power steering device may not operate normally due to the flow (leakage) other than through the motor coil.

In particular, the motor of the electric power steering device is used for both left and right rotations, and the brush 74, the brush holder 79, the commutator 78 and the support rod 80 shown in FIG.
a, and a brush holder 79 shown in FIG.
5 and a portion surrounded by the brush 74, the brush holder 79, the commutator 78, and the bracket 81 shown in FIG. 12 are concentrated and easily accumulated. An object of the present invention is to provide a motor and an electric power steering device that can solve the above problems.

[0008]

A motor according to a first aspect of the present invention includes a plurality of brushes sliding on a commutator, and a plurality of brushes arranged around the commutator and holding each brush therein. In a motor having a plurality of brush holders biasing toward the commutator and a housing in which the brush holder is fitted, in order to disperse 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.

In this motor, a plurality of brushes slide on the commutator, and a plurality of brush holders are juxtaposed around the commutator, and hold the respective brushes inside thereof and urge the brush toward the commutator. . Space is provided between adjacent brush holders and between the brush holder and the housing to disperse the abrasion powder of the brush generated by sliding with the commutator. Does not cause malfunction due to

According to a second aspect of the present invention, there is provided a motor comprising: a plurality of brushes sliding on a commutator; a plurality of brush holders for holding the respective brushes therein and for urging toward the commutator; In a motor including a brush holder frame for fixing a holder and a housing for fitting the brush holder frame therein, a space for dispersing abrasion powder of the brush generated by sliding with the commutator is provided in the housing. And an insulator interposed between the brush holders.

In this motor, a plurality of brushes slide on the commutator, and a plurality of brush holders hold each of the brushes therein and urge the brush toward the commutator. The brush holder frame fixes a plurality of brush holders, and the housing internally fits the brush holder frame. Since the space for dispersing the abrasion powder of the brush generated by sliding with the commutator is provided by interposing the insulator between the housing and the brush holder, the abrasion powder hardly concentrates and accumulates. Since the insulator insulates the brush and the brush holder from the housing, malfunction does not occur due to electric leakage.

According to a third aspect of the present invention, there is provided an electric power steering apparatus comprising: a motor according to claim 1 or 2; a control unit for controlling the driving of the motor in accordance with steering of a steering means; Transmission means for transmitting to the picking mechanism.

In this electric power steering apparatus, the control unit controls the driving of the motor described in claim 1 or 2 in accordance with the steering of the steering unit, and the transmission unit transmits the rotational force of the motor to the steering mechanism. The transmission does not cause malfunction due to electric leakage.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing an embodiment. FIG. 1 is a sectional view showing a configuration of an embodiment of a motor and an electric power steering device according to the present invention. However, in order to show the cross section of the brush holder 23, the cross section of the motor 7 is shown at about 45 degrees before. This electric power steering apparatus has a bar input hole 1a, and a cylindrical input shaft 1 whose upper end (right end in the figure) is connected to a steered wheel (not shown) for steering.
And a torsion bar 3 which is inserted into the bar insertion hole 1a and 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).

The electric power steering apparatus further includes a steering assist motor 7 mounted on a first housing 6 that houses the input shaft 1 and the output shaft 5, and a steering assist motor 7 that is housed in the housing 6. A torque sensor 8 that detects a torque applied to the input shaft 1 by rotation by the torsion generated in the torsion bar 3, and a motor 7 that is connected to the torque sensor 8 and is based on the torque detected by the torque sensor 8.
And a control unit 9 for controlling the driving of the motor 7,
And a transmission means 10 for transmitting to the

The lower end of the output shaft 5 is provided with a pinion of a steering mechanism (not shown) having a rack shaft extending in the left-right direction at the front of the vehicle body and a pinion meshing with a middle portion of the rack shaft. Connected to the upper end of the pinion shaft. A torque sensor 8 is connected to an input section of the control section 9 using a microprocessor, and a motor drive circuit 11 of the motor 7 is connected to an output section of the control section 9.

The transmission means 10 comprises a small gear 10a which is a hypoid pinion and a large gear 1 which is a hypoid wheel.
0b, and the small gear 10a is formed integrally with the end of the rotor shaft 76 of the motor 7. The large gear 10 b has teeth on one side of a conical portion, and an inner peripheral surface is fitted to an intermediate portion of the output shaft 5.

The motor 7 is mounted on the first housing 6.
A cylindrical stator 71 fixed in a cylindrical second housing 70 detachably connected via a bracket 70a (a housing of the motor), and a rotation rotatably arranged in the stator 71. A brush 72 attached to the bracket 70a via the respective brush holders 23 and sliding on a commutator 78 described later.
Each of the brushes 74 is 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.

The rotor 72 has a rotor shaft 76 rotatably supported in the second housing 70 via respective bearings 75 via respective bearings 75, and a drive winding fixed to an intermediate portion of the rotor shaft 76. Commutator 78 sliding on wire 77 and brush 74
And the commutator 78 is connected to the drive winding 77.

The two brush holders 23 are fixed to the inside of the cylindrical brush holder frame 22 at a position separated by about 90 degrees so that each opening faces the center of the rotor shaft 76. The brush holder 23 holds the majority part of the brush 74 by fitting it inside. The brush holder plate 20 is sandwiched between the brush holder frame 22 and the bracket 70a.

FIG. 2 is an external view showing the brush holder 23. As described above, the two brush holders 23 are fixed to the inside of the cylindrical brush holder frame 22 to be fitted in the bracket 70a with the brush holder plate 20 interposed therebetween, and are separated by approximately 90 degrees. In the position
Each opening is provided so as to face the center of the brush holder frame 22. The brush holder 23 is a hollow cylindrical shape with a bottom, and holds a majority portion of a brush 74 slightly smaller than the inner diameter by fitting it into the inside thereof. Since a support bar for mutually supporting the brush holders 23 is not provided between the two brush holders 23 shown in D, a large space can be secured, and the wear of the brush 74 caused by sliding with the commutator 78 is achieved. Powder can be dispersed.

FIG. 3 shows the brush 74 and the brush holder 23.
It is sectional drawing which expands and shows the installation state of. The brush holder 23 includes a motor bracket 70a (housing).
The brush 74 is supported by the brush holder frame 22 fitted therein, and the majority of the brush 74 is fitted and held inside the brush holder frame 22, and the brush 74 is fixed to the rotor shaft 76 by a spring 73 provided at the bottom.
To the direction of the commutator 78 fitted coaxially to the outside.

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 between the brush holder 23 and the bracket 70a as described above. The space between them is maintained and the creepage distance is kept long. Therefore, abrasion powder 12 of brush 74 generated by sliding with commutator 78 can be dispersed in the space. In addition, the brush holder plate 20, which is an insulator, insulates the brush 74, the brush holder 23, and the bracket 70a from each other.

Hereinafter, the operation of the motor and the electric power steering apparatus having the above-described configurations will be described. In this electric power steering device, the steering torque applied to the steered wheels is determined by the relative angular displacement between the input shaft 1 and the output shaft 5 coaxially connected to the input shaft 1 via the torsion bar 3 by the torque sensor 8. To detect. The control unit 9 controls the driving of the steering assist 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 by the steering mechanism into a movement of the front wheels of the vehicle in the left-right direction.
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.

In the motor 7, a brush 7 indicated by D in FIG.
4. Since the space surrounded by the brush holder 23 and the commutator 78 and the space surrounded by the brush 74, the brush holder 23, the commutator 78 and the bracket 70a shown by F in FIG. The abrasion powder 12 of the brush 74 generated by the sliding can be dispersed, and the leakage of the abrasion 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 70 a, the brush holder plate 20, which is an insulator, is kept on the brush holder 23 and the bracket 70 a. Insulation between them can be maintained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of an embodiment of a motor and an electric power steering device according to the present invention.

FIG. 2 is an external view showing a brush holder of the motor according to the present invention.

FIG. 3 is an enlarged sectional view showing an installed state of a brush and a brush holder of the 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 an installed state of a brush and a brush holder of a conventional motor.

[Explanation of symbols]

 Reference Signs List 7 motor 9 control unit 10 transmission means 12 brush wear 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)

[Claims] 1. A plurality of brushes sliding on a commutator, a plurality of brush holders arranged in parallel around the commutator, holding each brush therein and biasing the brush toward the commutator; In a motor having a housing in which the brush holder is fitted, a space for dispersing abrasion powder of the brush generated by sliding with the commutator is provided between adjacent brush holders and between the brush holder and the brush holder. A motor provided between the housing and the housing. 2. A plurality of brushes sliding on a commutator, a plurality of brush holders holding respective brushes in the commutator and urging the brushes toward the commutator, and a brush holder for fixing the plurality of brush holders. In a motor comprising a frame and a housing in which the brush holder frame is fitted, a space for dispersing abrasion powder of the brush generated by sliding with the commutator is provided between the housing and the brush holder. A motor characterized by being provided by interposing an insulator. 3. A motor according to claim 1 or 2,
An electric power steering apparatus, comprising: a control unit that controls the driving of the motor in accordance with steering of a steering unit; and a transmission unit that transmits a rotational force of the motor to a steering mechanism.