JPH02124367A - Electric power steering device - Google Patents

Abstract

PURPOSE:To reduce the number of parts used and enhance easiness in assembling works by forming a steering mechanism, which is fixed to a car body, etc., maneuvered through steering operation, in such a way as consolidated with a torque sensor assembly to sense the steering torque. CONSTITUTION:A steering mechanism 2 has a worm shaft 4 rotated by turning a steering wheel, and this rotation swings a sector 22, i.e., a pitman arm 23, through a ball nut 21, and thus a coupling 25 and a drag rod 24 are tracted to accomplish steering of wheels. Inside of a housing 2a of this steering mechanism 2, a torque sensor assembly 50 is fitted at the other end of the worm shaft 4. This assembly 50 is so constructed that the deflection of a spring 29 in the assembly 50 when a load greater than the set load on the spring is applied to the tip of the pitman arm 23, is sensed by a potentiometer 26 through a lever 31, etc., and in response to this output a motor for steering aid is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electric power steering device. More specifically, it relates to an electric power steering device for vehicles used mainly for cargo handling and transportation, which uses the driving force of an electric motor to lighten the steering force. The present invention relates to an electric power steering device that integrally incorporates a three-dimensional structure.

(Prior Art) An electric power steering device generally includes a steering assembly including a steering wheel and a steering mechanism, a torque sensor assembly, an actuator connected to a wheel steering link mechanism, a controller, and the like.

The steering mechanism of the steering assembly, which is usually fixed to the vehicle body, is connected to a torque sensor assembly by a connecting arm, etc., and the torque sensor assembly, which detects the load from the tires, that is, the wheels, is connected to the actuator. and moves in conjunction with the actuator. An electric motor is connected to this actuator so that it can freely drive the seven actuators, and the torque sensor assembly and electric motor are connected to the controller by wiring (harness) in order to exchange signals with the controller. There is. An example of this type is disclosed in, for example, Japanese Utility Model Application Publication No. 81-145071.

A steering mechanism composed of a ball nut or the like is activated by operating a steering wheel, drives an actuator via a torque sensor assembly, and steers the wheels. At this time, the load from the wheels is detected by the torque sensor assembly, so
When the load exceeds a predetermined value, the electric motor operates to drive the actuator to assist in turning the wheels, thereby reducing the force required for steering operation, that is, steering operation.

(Problems to be Solved by the Invention) In the conventional device described above, the steering mechanism and the torque sensor assembly are connected by a pitman arm or the like, and the torque sensor assembly is connected to the actuator by a link mechanism such as a connection arm. is connected to. The torque sensor assembly is held in a suspended state by link mechanisms at both ends of the torque sensor assembly. Therefore, when the steering device operates, as the actuator moves in the axial direction, the torque sensor assembly also moves by the pitman arm rotatably supported by the steering mechanism.

As previously discussed, the torque sensor assembly is hardwired to the controller. The controller is fixed to a part of the vehicle body, but the torque sensor assembly is suspended in the air and moved as described above.
The wiring between the torque sensor assembly and the controller will also move by expanding and contracting. Therefore, there has been a problem in that the amount of movement of the torque sensor assembly and the movement of the wiring must be assumed in advance and work procedures, such as when assembling a vehicle, must be considered.

Furthermore, since the torque sensor assembly having the function of detecting torque moves, there is a possibility that the detector fe of the sensor may be adversely affected.

Accordingly, an object of the present invention is to provide an electric power steering device in which there is no need to pay attention to wiring and the number of parts is reduced by integrating a steering mechanism and a torque sensor assembly.

(Means for Solving the Problems) In order to achieve the above-mentioned objects, an electric power steering device of the present invention is provided.

A steering mechanism (2) fixed to a vehicle body etc. that is operated by a steering operation, a link mechanism (23, 24) that steers wheels according to the amount of steering by the steering mechanism, and a steering torque that is detected. A torque sensor assembly (50), an electric motor (14) that drives the link mechanism based on detection information from the torque sensor assembly to assist in steering the wheels, and detection information from the torque sensor assembly. and a controller (13) that controls the electric motor based on the torque sensor assembly, and the torque sensor assembly is configured integrally with the steering mechanism.

(Function) As configured as described above, in the one-drive power steering system of the present invention, there is no movement of the wiring between the torque sensor assembly and the controller, and processing work such as wiring arrangement is eliminated. becomes easier.

(Example) Hereinafter, an example of the present invention will be described in detail based on the accompanying drawings. In the drawings, the same parts are indicated by the same reference numerals.

FIG. 1 shows an overall system diagram of the electric power steering device of this embodiment. Steering operation of handle 1 (rotation operation)
The rotation of the steering shaft 3 is controlled by the worm shaft 4 of the steering gear 4#2 which is fixed to the vehicle body etc. via the joint 5.
transmitted to. Based on FIG. 2, the rotation of the shaft 4 is extracted as a slow swinging movement of the pitman arm 23, as will be described later, and is caused by a substantially axial movement of the drag rod 24, which is connected at one end via a connecting portion 25. converted as

A torque sensor assembly 50, which will be described later, is integrated into the steering mechanism 2. Information regarding the load on the wheels detected by the torque sensor assembly 50 is transmitted to the torque sensor assembly 50 and a controller 13 fixed to the vehicle body or the like.
The signal is sent to the controller 13 as a signal via the wiring 34 connecting the two.

The other end of the drag road 24 is connected to a connecting part 9a to a 7-cut unit 9 that is movable in the axial direction to steer the wheels.
are connected in.

Therefore, in response to the axial movement of the drag rod 24,
Actuator 9 also moves in the axial direction. The actuator 9 is disposed in a cylinder member 11 so as to be freely movable in the axial direction, and an electric motor, that is, an electric motor 14 is provided in the cylinder member 11 so as to drive the seven actuators 9 in the axial direction. Electric motor 14 is connected to controller 13 via wiring 37.

The actuator 9 is connected to the transmission plate IO by a link 18. The transmission plate 10 is rotatable around a fixed shaft 15 fixed to a vehicle body or the like. One end of a link arm 16 is further connected to the transmission plate 10, and the other end of this link arm 16 is connected to a knuckle arm 17 of a wheel 19 (tire not shown). The wheels 19 are steered by the axial movement of the actuator 9 via the link mechanism described above.

FIG. 2 is a longitudinal sectional view of the steering mechanism 2 shown in FIG. 1, showing details of the steering mechanism 2 and the torque sensor assembly 50.

The worm shaft 4 is disposed in a housing 2a in a so-called "ball nut type" steering mechanism z, and a guide 4
0, the ball 41 and the nut 42 are engaged with a known ball nut part 21. The nut 42 meshes with the sector 22, which is rotatable about a pivot shaft 43. Therefore, the rotation of the nut 42 is converted into a turning motion of the sector 22, which is taken out as a swinging motion of the pitman arm 23 in the direction of arrow A. The movement beyond the pitman arm 23 is as described above.

Inside the housing 2a of the steering mechanism 2.

At the other end of the worm shaft 4, a torque sensor assembly 50 protected by a cover 44 is provided integrally with the steering mechanism 2.

The torque sensor assembly 50 is fixedly fitted to the worm shaft 4 and has bearing rings 27 and 28 provided at a predetermined interval, and contacts the bearing rings 27 and 28 between the bearing rings 27 and 28 to connect the worm shaft 4.
an intermediate ring 30 fitted into the bearing rings 27 and 28;
A spring 29 is provided between the spring 29 and the intermediate ring 30, and a circumferential groove 30a is provided at a substantially intermediate position in the axial direction of the intermediate ring 30 and extends with a predetermined length. One end 31a of the shaft 31, which is rotatably supported around a shaft 32, is fitted into this groove 30a without play in the axial direction. The other end of the lever 31 is an extension 31b.

The extension portion 31b of the lever 31 is housed within a joint portion 35 that protrudes from the housing 2a of the steering mechanism 2. A voltage displacement meter 26 such as a potentiometer is fixed to the side wall of the node 35, and a pin 33 for detecting displacement of the lever 31 projects into the node 35. To this pin 33,
Extension of the aforementioned lever 31! The wash end of 31b is configured to come into contact with it.

This torque sensor assembly 50 operates as follows. Link mechanism with wheels, actuator9. When a load larger than the set load of the spring 29 in the torque sensor assembly 50 is applied to the tip of the pitman arm 23 from the wheel (tire) via the drag rod 24 or the like, that is, when it is sensed, the worm shaft 4 responds to the biasing force of the spring 29. The ball nut part 21 moves forward or backward along the screw lead of the ball nut part 21 in the axial direction.

When the worm shaft 4 moves in the axial direction, the bearing rings 27 and 28 fixed thereto also move, causing the spring 29 to bend. At this time, the intermediate ring 30 also moves together, so the lever 3
The end portion 31a of one pivots around the shaft 32. Therefore.

The extension 31b opposite the end 31a pivots about the axis 32 in the opposite direction to the end 31a.

In order to amplify the amount of movement of the worm shaft 4 by t<-31, the extension part 31b needs to extend a relatively long distance with respect to the end part 31a. Since the tip of the extension 31b is in contact with the pin 33 of the voltage displacement meter 26,
The pin 33 expands and contracts slowly depending on the turning state of the spreading portion 31b. The amount of expansion and contraction of the pin 33 is converted into an electrical signal inside the voltage displacement meter 26 and sent to the controller 13 via the wiring 34.
is sent to; controls the electric motor 14.

Note that the torque sensor assembly 50 is centered by the spring 29 unless a load greater than the set load is applied. The steering mechanism 2 is of a type in which the worm shaft 4 moves in the axial direction when a force (input torque) greater than a set centering load is applied.

As can be seen from the above description, the wiring 34 does not move while the steering mechanism 2 and the torque sensor assembly 50 are in operation.
This is because the steering mechanism 2 and the controller 13 are fixed, and the torque sensor assembly 50 is integrally formed with the fixed steering mechanism 2. Furthermore, in the past, the steering mechanism 2 and the torque sensor assembly were separate bodies, so a connecting arm was needed to connect them, but according to the present invention, this connecting arm is no longer necessary. Therefore, the number of parts can be reduced.

(Effects of the Invention) According to the electric power steering device of the present invention explained above,
The following effects can be obtained.

Since the wires do not move, there is no need to worry about handling the wires, making work easier.

Since the steering mechanism and the torque sensor assembly are integrally formed, the conventionally necessary connecting arm is no longer necessary, and the number of parts is reduced.

Since the torque sensor assembly is in a fixed state, the accuracy of detecting input torque is improved.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing a steering device according to an embodiment of the present invention. FIG. 2 is a longitudinal sectional view of the steering mechanism of FIG. 1. [Explanation of symbols of main parts]

Claims (1)

[Claims] A steering mechanism fixed to a vehicle body or the like that is operated by a steering operation, a link mechanism that steers wheels according to the amount of steering by the steering mechanism, a torque sensor assembly that detects steering torque, and the torque sensor. It consists of an electric motor that drives the link mechanism based on detection information from the assembly to assist in steering the wheels, and a controller that controls the electric motor based on the detection information from the torque sensor assembly. An electric power steering device characterized in that a sensor assembly is configured integrally with the steering mechanism.