JP3886278B2 - Electric power steering device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in an electric power steering apparatus that applies an assist force by an electric motor.
[0002]
[Prior art]
Conventionally, as this type of electric power steering apparatus, as disclosed in, for example, Japanese Patent Application Laid-Open No. 9-30434, there is an electric motor and its controller that are housed in a common case and unitized. This eliminates the need for external wiring connecting the controller and the motor, and can suppress the influence of radiation noise caused by the motor drive current.
[0003]
[Problems to be solved by the invention]
However, in such a conventional electric power steering device, it is considered that the brush wear powder generated in the motor chamber can easily enter the controller chamber by housing the motor and the controller in a common case. It is done.
[0004]
The present invention has been made in view of the above problems, and an object of the present invention is to suppress adverse effects of brush abrasion powder and the like in an electric power steering apparatus in which an electric motor and a controller are unitized.
[0005]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a motor shaft that rotates in cooperation with a steering mechanism, a commutator that is fixed to the motor shaft and is electrically connected to a coil, a pair of brushes that are in sliding contact with the commutator, a motor chamber in which the brush is disposed, and a brush Generated in the motor room, comprising a controller for supplying drive current, a controller room in which the controller is disposed, a partition wall that divides the motor room and the controller room, and a wiring hole that passes through the partition wall and connects the controller and the brush. This is applied to an electric power steering apparatus in which wear powder of the brush to be moved may enter the controller room through between the wiring hole and the wiring .
[0006]
Then, the motor shaft is arranged substantially horizontally, the brush sliding directions are arranged substantially horizontally, and the brushes are arranged on the common center line L so as to face each other with the commutator interposed therebetween. The motor is mounted on the vehicle so that L is substantially horizontal, and the wiring hole is disposed above the brush.
[0007]
According to a second invention, in the first invention, when a straight line connecting the rotation center of the motor shaft and the center of the wiring hole is a wiring center line T, the sandwiching angle θ between the two wiring center lines T is 60 to 120 °. The range was set.
[0008]
According to a third invention, in the first or second invention, a rack shaft that cooperates with the steering mechanism, a pinion that transmits the rotation of the handle to the rack shaft, and an assist pinion that transmits the rotation of the motor to the rack shaft are provided. did.
[0009]
Operation and effect of the invention
In the first invention, since the abrasion powder of the brush falls in a region below each brush holder in the motor chamber, the sliding direction of the brush is disposed substantially horizontally and the wiring hole is disposed above the brush. The wear powder can be prevented from entering the controller chamber through the wiring hole, and the controller can be prevented from malfunctioning.
[0010]
In addition, by sliding the brush in a substantially horizontal direction, the vertical vibrations of the vehicle are not input in the brush sliding direction, preventing the brush from coming off the commutator and causing poor contact, thus stabilizing the motor operation. Can be made.
[0011]
In the second invention, by setting the sandwiching angle θ of the wiring center line T in the range of 60 to 120 ° and sufficiently securing the height of each wiring hole with respect to each brush, the wear powder passes through the wiring hole. Intrusion into the controller room can be effectively suppressed.
[0012]
In the third aspect of the present invention, the assist pinion that transmits the rotation of the motor to the rack shaft is a two-pinion type structure that is provided separately from the pinion that transmits the rotation of the handle, so that the motor can be arranged in a limited space of the vehicle. The motor can be easily arranged so that the brushes slide in a substantially horizontal direction.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0014]
As shown in FIG. 1, the rack and pinion type steering device is a rack in which the rotation of the handle 1 steered by the driver is transmitted to the pinion 3 via the input side shaft 2 and the output side shaft 15 and meshed with the pinion 3. As the shaft 4 moves in the left-right direction, the direction of the wheel 7 changes via the left and right tie rods 5 and the knuckle arm 6.
[0015]
The rack assist type electric power steering apparatus includes an assist pinion 12 that meshes with the rack shaft 4, and transmits the rotation of the electric motor 50 to the assist pinion 12 to perform power assist.
[0016]
As means for detecting the steering torque, a torsion bar 16 is interposed between the input side shaft 2 and the output side shaft 15, and a torque sensor 17 for detecting the torsion amount of the torsion bar 16 is provided.
[0017]
The controller 20 inputs a steering torque detection signal sent from the torque sensor 17 and a vehicle speed detection signal sent from a vehicle speed sensor (not shown), and controls the current supplied to the coil of the motor 50 according to these signals. Then, the output torque (power assist force) of the motor 50 is adjusted.
[0018]
The controller 20 includes a drive circuit that converts a current from a battery (not shown) into a drive current to the motor 50 and outputs it, a control circuit that processes the signal, and the like. Connected by.
[0019]
As shown in FIG. 2, the motor 50 includes a motor shaft 52 that is rotatably supported, a coil 55 that is fixed in the middle of the motor shaft 52, and a commutator that is also fixed in the middle of the motor shaft 52 and is conducted to the coil 55. 57, a pair of brushes 58 that are in sliding contact with the commutator 57 and that supplies a drive current from the controller 20, a stator 56 formed of a permanent magnet fixed around the coil 55, and the like.
[0020]
A part of the motor shaft 52 is rotatably supported by the case 30 via a bearing 53, and one end of the motor shaft 52 is rotatably supported by the motor housing 40 via a bearing 54. The other end of the motor shaft 52 is connected to the shaft 12A of the assist pinion 12 via a torque limiter 18 and a reduction mechanism including a worm gear 75 and a wheel gear 76 in the gear housing 37, for example. Is transmitted to the assist pinion 12 via. The case 30 is formed with a center hole 31 through which the motor shaft 52 passes and an annular recess 35 into which the bearing 53 is fitted.
[0021]
As shown in FIG. 3, the motor 50 includes a pair of brush holders 59 that slidably support the brushes 58. Each brush holder 59 has a cylindrical holder portion 63, and a rod-like brush 58 is slidably fitted to the holder portion 63. The brush 58 is pressed against the commutator 57 by the biasing force of the spring 69.
[0022]
By the way, when the vibration of the vehicle is input in the sliding direction of each brush 58, the brush 58 may move away from the commutator 57 and cause a contact failure.
[0023]
As a countermeasure, the brushes 58 are arranged so as to slide in a substantially horizontal direction so that the vertical vibration of the vehicle is not input in the sliding direction of the brushes 58. That is, the brushes 58 are arranged on a common center line L so as to face each other with the commutator 57 interposed therebetween, and the motor 50 is mounted on the vehicle so that the center line L is substantially horizontal.
[0024]
Each brush holder 59 is formed of a metal plate, and guides current from the controller 20 to the brush 58 via a wire-shaped pigtail wire 64. Each brush holder 59 has a terminal 66 connected to the controller 20 and a terminal 65 to which one end of the pigtail wire 64 is connected, and these are integrally formed. The other end of the pigtail line 64 is coupled to the brush 58.
[0025]
The motor 50 and the controller 20 constituting the electric power steering apparatus are accommodated through a common case 30 to unitize them. In FIG. 2, a motor chamber 39 for housing the motor 50 is defined between the case 30 and the motor housing 40, while the controller 20 is disposed between the case 30 and the gear housing 37. A controller room 38 is defined.
[0026]
The cylindrical case 30 has a disk-shaped partition wall 32 that partitions the motor chamber 39 and the controller chamber 38, a flange portion 33 for fitting the motor housing 40, and a flange portion 34 for fitting the gear housing 37. These are integrally formed using aluminum as a material.
[0027]
A disk-shaped plate 61 made of an insulating material is fastened to the side of the motor chamber 39 of the partition wall 32 through a screw 62 and the brush holder 59 is coupled to the plate 61.
[0028]
A substrate 71 of the controller 20 is attached to the partition wall 32 on the controller chamber 38 side, and a cover 72 made of an insulating material covering a circuit provided on the substrate 71 is interposed.
[0029]
A pair of wiring holes 29 through which the respective terminals 66 are inserted is formed in the partition wall 32 of the case 30. Each wiring hole 29 penetrates the partition wall 32 and communicates the motor chamber 39 and the controller chamber 38. The terminal 66 integrally formed with the metal brush holder 59 is inserted through the wiring hole 29 and fixed to a terminal (not shown) provided on the controller 20 side by soldering.
[0030]
By the way, although the abrasion powder of the brush 58 is generated in the motor chamber 39, if a large amount of abrasion powder enters the controller chamber 38 through the wiring hole 29, it causes a malfunction of the controller 20.
[0031]
As countermeasures, the brushes 58 are arranged so as to slide in a substantially horizontal direction, and the wiring holes 29 are arranged above the brushes 58 so that the abrasion powder of the brushes 58 passes through the wiring holes 29 and is placed in the controller chamber. 38.
[0032]
Assuming that a straight line passing through the center of each wiring hole 29 and the rotation center O of the motor shaft 52 is a wiring center line T, the sandwiching angle θ of each wiring center line T is set in a range of 60 to 120 °, and A sufficient height of the wiring hole 29 is ensured. In the present embodiment, the wiring center lines T are arranged so as to have a sandwiching angle θ of about 90 °.
[0033]
Next, the operation will be described.
[0034]
The controller 20 inputs detection signals of steering torque and vehicle speed, and supplies electric power to the motor 50 in accordance with these signals. The motor 50 is supplied with current supplied from the controller 20 to the coil 55 via the brush holder 59, the pigtail wire 64, the brush 58, the commutator 57, and the like, and generates a power assist force corresponding to the electric power.
[0035]
By arranging the brushes 58 to slide in a substantially horizontal direction, the vertical vibrations of the vehicle are not input in the sliding direction of the brushes 58, and the brushes 58 are separated from the commutator 57 and cause poor contact. The operation of the motor 50 can be stabilized.
[0036]
By adopting a two-pinion type structure in which the assist pinion 12 is provided separately from the pinion 3, the degree of freedom in arranging the motor 50 in a limited space of the vehicle is increased, so that each brush 58 slides in a substantially horizontal direction. The motor 50 can be disposed.
[0037]
By housing the motor 50 and the controller 20 constituting the electric power steering apparatus in a common case 30 and unitizing them, an external wiring connecting the controller 20 and the motor 50 becomes unnecessary. By shortening the wiring connecting the drive circuit of the controller 20 and the brush 58 with the brush holder 59 and the pigtail line 64, the power transmission loss can be reduced and the voltage drop can be suppressed.
[0038]
However, when the motor 50 and the controller 20 are housed in the common case 30, there is a possibility that the abrasion powder of the brush 58 generated in the motor chamber 39 may enter the controller chamber 38. In response to this, each brush 58 is arranged so as to slide in a substantially horizontal direction, and each wiring hole 29 is arranged above each brush 58. Since the abrasion powder of the brush 58 falls and accumulates in the motor chamber 39 in a region below each brush 58, the abrasion powder can be prevented from entering the controller chamber 38 through the wiring hole 29, and the malfunction of the controller 20 can be prevented. It can be prevented from coming.
[0039]
The sandwiching angle θ of each wiring center line T is set in the range of 60 to 120 °, and the height of each wiring hole 29 with respect to each brush 58 is sufficiently secured, so that the wear powder passes through the wiring hole 29 and passes through the controller room 38 can be effectively prevented from entering.
[0040]
As another embodiment, as shown by a broken line in FIG. 1, the motor 50 may directly drive the pinion 3. Further, the motor 50 may be configured to drive the input side shaft 2 via the gear device 70. In this case, the assist pinion can be abolished although the degree of freedom of arrangement of the motor 50 is reduced as compared with the two-pinion type structure in the embodiment.
[Brief description of the drawings]
FIG. 1 is a system diagram showing an embodiment of the present invention.
FIG. 2 is a cross-sectional view of a motor and the like.
FIG. 3 is a front view of the brush holder and the like.
FIG. 4 is a sectional view of the case and the like.
[Explanation of symbols]
3 Pinion 4 Rack shaft 12 Assist pinion 20 Controller 29 Wiring hole 30 Case 32 Bulkhead 38 Controller chamber 39 Motor chamber 50 Motor 52 Motor shaft 57 Commutator 58 Brush 59 Brush holder 64 Pigtail wire 66 Terminal

Claims (3)

A motor shaft that rotates in conjunction with a steering mechanism, a commutator that is fixed to the motor shaft and is connected to a coil, a pair of brushes that are in sliding contact with the commutator, a motor chamber in which the brush is disposed, and a drive current for the brush A controller chamber in which the controller is arranged, a partition wall that partitions the motor chamber and the controller chamber, and a wiring hole that passes through the partition wall and connects the controller and the brush, In the electric power steering apparatus in which the abrasion powder of the brush generated in the motor chamber may enter the controller chamber through between the wiring hole and the wiring, the motor shaft is disposed substantially horizontally. faces disposed substantially horizontally sliding direction of the brush, the commit each of said brushes at the common center line L Arranged to face each other across the stator, the motor so that the center line L is substantially horizontal and mounted on a vehicle, the electric power steering apparatus, wherein a wiring hole is arranged above the brush. When a straight line connecting the rotation center of the motor shaft and the center of the wiring hole is a wiring center line T, the sandwiching angle θ between the two wiring center lines T is set in a range of 60 to 120 °. The electric power steering apparatus according to claim 1. 3. A rack shaft cooperating with the steering mechanism, a pinion that transmits rotation of a handle to the rack shaft, and an assist pinion that transmits rotation of the motor to the rack shaft. The electric power steering apparatus described.

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