JPH07309246A - Steering device - Google Patents

Abstract

PURPOSE:To make turning or sliding property of a rack shaft smooth and improve the steering sense of a steering device by arranging a ball screw mechanism and a motor provided in a housing at a specific position. CONSTITUTION:Both ends of a housing 1 molded integrally are supported through a bearing member 13 and a slide member 15 which are provided on the outer periphery of a rack shaft 2 at a specific interval, and a ball screw mechanism 16 and a motor 20 are provided between the bearing member 13 and the slide member 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric power steering device for an automobile, for example.

[0002]

2. Description of the Related Art An electric power steering system transmits a rotation of a steering wheel to a rack shaft via a pinion as left and right movements, and when steering wheels by steering tie rods connected to both ends of the rack shaft, steering is performed. Power steering is performed by detecting a steering torque of a shaft, driving an electric motor based on the detected value, and transmitting the driving force to a rack shaft through a ball screw mechanism. For example, the one disclosed in JP-A-59-50864 is known.

[0003]

However, in the electric power steering device disclosed in Japanese Patent Laid-Open No. 59-50864, the ball screw mechanism and the electric motor are provided in the two housings connected by the bolts, and the bearing member and the sliding member. It is difficult to make the rack shaft axis coincide with each other because there are many radial support points of the rack shaft, and an assembly error occurs due to variations in accuracy of each component. However, the ball nut mechanism and the electric motor cannot be arranged at predetermined positions, which eventually leads to deterioration of steering feeling and deterioration of drive efficiency of the electric motor.

[0004]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention slidably supports a rack shaft in which a pinion attached to a steering shaft meshes in a housing, and inside the housing, an outside of the rack shaft is supported. In a steering device in which an electric motor is coaxially arranged on the rack shaft and the torque generated by the electric motor is transmitted to a rack shaft via a ball screw mechanism, the housing is integrally formed, and a bearing member and a sliding member are mounted on the outer periphery of the rack shaft. The ball screw mechanism and the electric motor are disposed between the bearing member and the sliding member while being disposed via the moving member. At this time, it is preferable that the bearing member and the sliding member are provided near both ends of the integrally molded housing.

[0005]

The both ends of the integrally molded housing are supported via the bearing member and the sliding member which are provided on the outer periphery of the rack shaft at predetermined intervals, and the ball screw mechanism and the electric motor are provided between the bearing member and the sliding member. Is provided.

[0006]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a sectional view of a main portion of a steering device according to the present invention, FIG. 2 is an enlarged view showing a motor portion, and FIG. 3 is an overall configuration diagram of the steering device according to the present invention.

In the drawing, reference numeral 1 designates a housing, which is integrally formed into a tubular shape comprising a small diameter portion 1a, a large diameter portion 1b and an inclined portion 1c by a drawing process. A rack shaft 2 is inserted into the housing 1, and the rack shaft 2
Both ends of the left and right protrude from the housing 1 and the gear case 3 to the left and right, and tie rods 4 are connected to the ends thereof, and the rack shaft 2 moves in the left and right directions to steer the left and right wheels 5 through the tie rods 4.

In the gear case 3, a steering shaft 7 rotated by a steering wheel 6 is connected via a torsion bar 8 and a universal joint 9 and a steering torque detecting mechanism (not shown) is arranged. A pinion 10 is provided at the lower end of the rack, and the pinion 10 is engaged with a rack 11 formed on the rack shaft 2.

A long cylindrical hollow shaft 12 constituting a rotor is arranged on the outer periphery of the rack shaft 2. A bearing (bearing member) 13 using the hollow shaft 12 as an inner race is provided at one end of the hollow shaft 12, and an outer circumference of the outer race 13a is provided on the gear case 3.
Is fixed to the inner circumference of the end of the gear case 3, and one end (on the large diameter portion 1b side) of the housing 1 is fixed to the outer circumference of the end of the gear case 3.

On the other hand, the other end of the housing 1 (small diameter portion 1
a side) is a mounting member 14 and a bush (sliding member) 15
It is slidably supported by the rack shaft 2 inserted into the housing 1 via the.

Further, a piece type nut 17 constituting a ball screw mechanism 16 is engraved on the inner circumference of the other end of the hollow shaft 12, and between the nut screw 17 and a screw groove 18 engraved on the rack shaft 2. Hold the steel ball 19.

Further, an electric motor 20 is arranged between the outside of the hollow shaft 12 and the inside of the large diameter portion 1b.
In this embodiment, a brushless type is applied as the electric motor 20. This electric motor 20 has a large diameter portion 1b.
An iron core 22 around which a winding wire 21 that constitutes a stator is wound is fixed to the inner peripheral surface of, and a permanent magnet 23 that constitutes a rotor is attached to the outer circumference of the hollow shaft 12.

Since the brushless type electric motor 20 described above has no brush, the position of the permanent magnet 23 is detected, and the current is supplied to the winding 21 at the commutation (switching of the winding current) according to the rotational position. There is a need to. Therefore, in this embodiment, the flange portion 3a at the end of the gear case 3 is connected to the external connecting portion 24 connected to the electric motor driving means (not shown) and the internal connecting portion 2 connected to the electric motor 20.
5 is integrally provided and a rotor rotation angle detecting means is provided inside the housing 1.

The rotation angle detecting means is a permanent magnet 2 which is a rotor.
Attach a Hall element (not shown) at a position facing 3
The position of the rotor is detected by detecting the position of the permanent magnet 23 with this Hall element. Reference numeral 26 is an IC substrate for signal processing such as amplification and waveform shaping after the detection and detection. As described above, by using the brushless type electric motor, the abrasion of the brush is eliminated, the durability of the electric motor is significantly improved, and the miniaturization can be achieved.

In the above structure, a signal from the steering torque detecting mechanism or the like is input to the control unit (ECU) 27, a predetermined process is performed based on the input value, and then a control signal for driving the electric motor 20 is supplied to the battery 28. The electric power is supplied to the electric motor drive means, and the electric motor 20 is drive-controlled at a predetermined commutation timing.

When the electric motor 20 is driven, the hollow shaft 12 rotates, and the rotation of the hollow shaft 12 is transmitted to the rack shaft 2 via the ball screw mechanism 16 as a lateral movement (power assist).

FIG. 4 is an enlarged view of an electric motor portion according to another embodiment, and the same members are designated by the same reference numerals. In this embodiment, the electric motor 20 has a permanent magnet 23 fixed to the inner peripheral surface of the large diameter portion 1b to form a stator, and the hollow shaft 12
An iron core 22 around which a winding wire 21 is wound is fixed to the outer peripheral surface of to form a rotor. Further, the ball screw mechanism 16 is formed by press-fitting the nut screw 29 into the inner peripheral surface of the other end of the hollow shaft 12 constituting the rotor and preventing the nut screw 29 from coming off with the circlip 30. A steel ball 19 is held between the formed thread groove 18.

The flange portion 3 at the end of the gear case 3
The electric current supplied through the external connecting portion 24 and the internal connecting portion 25 formed in a is supplied to the winding 21 coil through the brush 31 and the commutator 32 which are held inside the large diameter portion 1b, and the electric motor 20 is driven and controlled in the same manner as in the above embodiment.

[0019]

As described above, according to the present invention,
In a steering device in which torque generated by an electric motor is transmitted to a rack shaft via a ball screw mechanism, a housing integrally formed with a bearing member and a sliding member provided at a predetermined interval on the outer periphery of the rack shaft is provided. Since the ball screw mechanism and the electric motor are arranged between the bearing member and the sliding member, the rack shaft is supported at two places,
As compared with the conventional support, an assembly error due to variations in accuracy of each component is less likely to occur, and the ball screw mechanism and the electric motor can be arranged at a predetermined position. Therefore, the rotation or slidability of the rack shaft becomes smooth, and the steering feeling of the steering device is improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main portion of a steering device according to the present invention.

FIG. 2 is an enlarged view showing an electric motor part.

FIG. 3 is an overall configuration diagram of a steering device according to the present invention.

FIG. 4 is an enlarged view of an electric motor portion according to another embodiment.

[Explanation of symbols]

1 ... Housing, 2 ... Rack shaft, 7 ... Steering shaft, 10 ... Pinion, 13 ... Bearing (bearing member), 15 ... Bush (sliding member), 16 ... Ball screw mechanism, 20 ... Electric motor.

Claims (2)

[Claims] 1. A rack shaft in which a pinion attached to a steering shaft meshes is slidably supported in a housing, and an electric motor is coaxially arranged outside the rack shaft in the housing. In a steering device in which torque is transmitted to a rack shaft via a ball screw mechanism, the housing is integrally formed, and the housing is disposed on the outer periphery of the rack shaft via a bearing member and a sliding member, and the bearing A steering device in which the ball screw mechanism and an electric motor are arranged between a member and a sliding member. 2. The steering device according to claim 1, wherein the bearing member and the sliding member are provided near both ends of the housing.