JP2952910B2 - Electric power steering system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electric power steering apparatus. More specifically, the present invention relates to an electric power steering device for a vehicle mainly used for cargo handling, transportation, etc., which reduces a steering wheel operating force by a driving force of an electric motor, and more particularly, to a rotary type steering system. The present invention relates to an electric power steering apparatus in which a torque sensor assembly having a sensor is integrated.

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

Usually, a steering mechanism of a steering assembly fixed to a vehicle body or the like is connected to a torque sensor assembly by a connecting arm or the like, and a torque sensor assembly for detecting a load such as a tire, that is, a wheel, is connected to an actuator. It moves in conjunction with the actuator. An electric motor is connected to the actuator so that the actuator can be driven.The torque sensor assembly and the electric motor are used to transmit and receive signals to and from the controller.
Connected to the controller with wiring (harness). An example of this type is disclosed, for example, in Japanese Utility Model Laid-Open No. 61-145071.

A steering mechanism constituted by a ball nut or the like operates by operating a steering wheel, drives an actuator via a torque sensor assembly, and steers wheels. At this time, since the load from the wheels is detected by the torque sensor assembly, if the load is greater than or equal to a predetermined value, the electric motor operates to drive the actuator to assist in turning the wheels,
The steering operation, that is, the force required for steering operation is reduced.

(Problems to be Solved by the Invention) In the above-described conventional device, the steering mechanism and the torque sensor assembly are connected by a pitman arm or the like, and the torque sensor assembly is further actuated by a link mechanism such as a connection arm. It is connected to. The torque sensor assembly is held in a suspended state by link mechanisms at both ends thereof. 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 already described, the torque sensor assembly is hardwired to the controller. Although the controller is fixed to a part of the vehicle body, the wiring between the torque sensor assembly and the controller also extends because the torque sensor assembly moves while floating in the air as described above. It will move by shrinking or shrinking. Therefore, there has been a problem in that it is necessary to consider in advance the amount of movement of the torque sensor assembly and the movement of the wiring and to consider the work process in assembling a vehicle, for example.

Further, since the torque sensor assembly having the function of detecting torque moves, the detection function of the sensor may be adversely affected.

In order to solve the above-mentioned problems, the applicant of the present application has reduced the number of parts in the Japanese Patent Application No. 63-276092 (filed on November 2, 1988) by integrating the steering mechanism and the torque sensor assembly. We proposed an electric power steering device, eliminating the need to pay attention to wiring processing.

However, in the aforementioned Japanese Patent Application No. 63-276092,
It has been found that there are further problems as follows.

(1) Since a linear motion sensor (potentiometer) is used, if the distribution of the lever that swings by engaging with the telescopic pin for detection of this sensor is uneven, one end of the lever is supported to allow the lever to move. It is necessary to adjust the position of the sleeve member which is displaced in the axial direction in accordance therewith, so that the distribution of the levers is equalized, and this work is troublesome.

(2) Shim adjustment is required to bring out the electrical center of a direct acting potentiometer (voltage displacement meter).

(3) When the lever is operated, an angle is generated between the lever and the pin of the potentiometer. For this reason, a radial force is generated at the pin portion of the potentiometer, which may adversely affect the operation, durability, and the like of the potentiometer.

Therefore, an object of the present invention is to reduce the number of parts by integrating the steering mechanism and the torque sensor assembly without paying attention to the processing of the wiring, and to easily attach and adjust the sensor unit, It is an object of the present invention to provide an electric power steering device capable of ensuring the durability and the operation stability of the motor.

(Means for Solving the Problems) In order to achieve the above object, an electric power steering apparatus according to the present invention includes a steering mechanism (2) fixed to a vehicle body or the like operated by a steering operation; A link mechanism (23, 24) for turning wheels according to the steering amount of the mechanism, a torque sensor assembly (50) for detecting a turning torque, and a link mechanism based on detection information from the torque sensor assembly. An electric motor (14) for driving the link mechanism to assist in turning the wheels, and a controller (13) for controlling the electric motor based on detection information from the torque sensor assembly, wherein the torque sensor assembly is The torque sensor assembly is formed integrally with the steering mechanism and has a rotary sensor.

(Operation) With the configuration described above, in the electric power steering apparatus of the present invention, the movement of the wiring between the torque sensor assembly and the controller is eliminated, and processing operations such as wiring arrangement are easy. At the same time, the mounting and adjustment of the sensor unit are easy, and the durability and operation stability of the sensor unit can be secured.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same parts are denoted by the same reference numerals.

FIG. 1 shows an overall system diagram of the electric power steering apparatus of the present embodiment. The rotation of the steering shaft 3 by the steering operation (rotation operation) of the steering wheel 1 causes the joint 5 to rotate.
Is transmitted to the worm shaft 4 of the steering mechanism 2 fixed to the vehicle body or the like. 2, the rotation of the shaft 4 is taken out as the swinging motion of the pitman arm 23, as will be described later, and is substantially the axial motion of the drag rod 24, one end of which is connected via the connecting portion 25. Is converted.

A torque sensor assembly 50 described later is integrally incorporated in the steering mechanism 2. Information about the wheel load and the like detected by the torque sensor assembly 50 is transmitted as a signal to the controller 13 via a wiring 34 connecting the torque sensor assembly 50 and the controller 13 fixed to the vehicle body or the like.
Sent to

The other end of the drag rod 24 is connected at a connecting portion 9a to an actuator 9 that is movable in the axial direction to steer a wheel. Therefore, the actuator 9 also moves in the axial direction according to the movement of the drag rod 24 in the axial direction. The actuator 9 is disposed inside the cylinder member 11 so as to be movable in the axial direction. An electric motor, that is, an electric motor 14 is provided on the cylinder member 11 so as to drive the actuator 9 in the axial direction. The electric motor 14 is connected to the controller 13 via a wiring 37.

The actuator 9 is connected to the transmission plate 10 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 the link arm 16 is connected to a knuckle arm 17 of a wheel 19 (tire is 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 and shows details of the steering mechanism 2 and the torque sensor assembly 50.

The worm shaft 4 is disposed in a housing 2 a in a so-called “ball nut type” steering mechanism 2, and is provided with a guide 4.
0, a known ball nut portion 21 composed of a ball 41 and a nut 42 is engaged. The nut 22 is engaged with a sector 22 that is pivotable about a pivot shaft 43. Therefore,
The linear motion of the nut 42 is converted into a turning motion of the sector 22 and is taken out as a swing of the pitman arm 23 in the direction of the arrow A. The movement beyond the pitman arm 23 is as described above.

In the housing 2a of the steering mechanism 2, the worm shaft 4
A torque sensor assembly 50 protected by a cover 44 and a box 35 is provided integrally with the steering mechanism 2 at the other end of the steering mechanism 2. Reference numeral 51 denotes an oil seal fitted on the outer periphery of the worm shaft 4. The oil seal 51 is used for a voltage displacement meter or the like described later when the hydraulic oil in the steering mechanism 2 enters the torque sensor assembly 50 and The space between them is sealed so as not to affect them.

The torque sensor assembly 50 includes races 27 and 28 fixedly fitted to the worm shaft 4 and provided at predetermined intervals;
An intermediate ring 30 fitted on the worm shaft 4 in contact with the intermediate ring between the bearing rings 27 and 28;
A circumferential groove 30a having a predetermined length is engraved at a substantially intermediate position in the axial direction of the intermediate ring 30 and includes a spring 29 provided in parallel with the intermediate ring 30. In addition, one end 31a of a lever 31 pivotally supported on a shaft 32 as a center.
Are fitted so that there is no backlash in the axial direction.

As is clear from FIG. 2, the middle of the lever 31 is a circular portion.
The circular portion 31b is fitted with a shaft 32. Lever on the opposite side of end 31a across intermediate circular portion 31b
A U-shaped engaging portion 31c having two protruding portions 31d is provided at an end of 31.

The engaging portion 31c of the lever 31 is connected to the housing 2a of the steering mechanism 2.
Are housed in a box 35 protruding from the housing. A rotary voltage displacement meter 26 such as a potentiometer is fixed to a flange 35a extending from the side wall of the box 35. The voltage displacement meter 26 has a flange portion 26a as shown in FIG. 4, and the flange portion 26a and the flange 35a are
It is fixed by mounting means such as b. At this time, since the flange portion 26a is provided with the elongated hole 26b, when attaching the voltage displacement meter 26 to the box portion 35, the voltage displacement meter 26 is inserted into the elongated hole 26b.
The centering of the voltage displacement meter can be easily performed by positioning along the direction 26b, that is, by rotating in the direction of arrow B.

As shown in FIGS. 2, 3, and 4, an arm piece 53 is fixed to a rotatable center shaft 52 of the voltage displacement meter 26.
A shaft 55 is fixed to the arm piece 53. On axis 55,
A cylindrical member 54 is rotatably fitted to the shaft 55.

As is apparent from FIGS. 2 and 3, the cylindrical member 54
The lever 31 is engaged so as to be sandwiched between two projecting portions 31d of the engaging portion 31c of the lever 31. The distance between the outer diameter of the cylindrical member 54 and the inner surface of the protruding portion 31d is set to be substantially equal, so that there is no play in the engaging portion between the two. With the above configuration, when the lever 31 swings about the shaft 32 in the direction of the arrow C, the displacement amount is taken out as the amount of rotation of the arm piece 53 about the shaft 52 via the cylindrical member 54. Therefore, this rotation amount becomes an output of the voltage displacement meter 26 and is input to the controller 13 via the wiring 34.

The torque sensor assembly 50 operates as follows. When a load larger than the set load of the spring 29 in the torque sensor assembly 50 is applied from the wheel (tire) to the tip of the pitman arm 23 via the link mechanism with the wheel, the actuator 9, the drag rod 24, etc. The worm shaft 4 overcomes the urging force of the spring 29 and moves forward or backward in the axial direction.

When the worm shaft 4 moves in the axial direction, the bearing rings 27 and 28 fixed thereto also move, and the spring 29 bends. At this time, the intermediate ring 30 also moves integrally, so that the end of the lever 31
31a pivots about axis 32 in the direction of arrow C. Therefore,
The engagement portion 31c on the opposite side to the end 31a is an end around the shaft 32.
Turn in the opposite direction to 31a.

In order to amplify the amount of movement of the worm shaft 4 by the lever 31, the distance between the engaging portion 31c and the shaft 32 must be equal to the distance between the end 31a and the shaft 32.
Is relatively longer than the distance between Since the two protrusions 31d of the engagement portion 31c are engaged with the cylindrical member 54, the lever 3
According to the turning direction and the turning amount of 1, the shaft 52 rotates via the arm piece 53, and the output of the voltage displacement meter 26 is obtained. Arm piece
The rotation amount and direction of 53 are converted to electric signals inside the voltage displacement meter 26 and sent to the controller 13 through the wiring 34,
The electric motor 14 is controlled.

When a load greater than the set load is not applied, the torque sensor assembly 50 is centered by the spring 29. The steering mechanism 2 is configured such that when a force (input torque) greater than a set load for centering is applied, the worm shaft 4 moves in the axial direction.

As can be seen from the above description, the wiring 34 does not move during the operation of the steering mechanism 2 and the torque sensor assembly 50. This is because the steering mechanism 2 and the controller 13 are fixed and the torque sensor assembly 50 is fixed.
This is because they are integrally formed. Conventionally, since the steering mechanism 2 and the torque sensor assembly were separate bodies,
Although a connecting arm for connecting the two is required, according to the present invention, the connecting arm is not required. Therefore, the number of parts can be reduced. Also, compared to the conventional method, it is easier to adjust the mounting of the sensor such as centering the voltage displacement meter when mounting it, and no extra force is applied to the detection part of the sensor, so that the durability and operation stability of the sensor are stable Can be secured.

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

Since the wiring does not move, there is no need to pay attention to the processing of the wiring, and the work processing becomes easy.

Since the steering mechanism and the torque sensor assembly are integrally formed, the connecting arm, which is conventionally required, is not required, and the number of parts is reduced.

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

In addition, since a rotary sensor (voltage displacement meter) is used, the mounting and adjustment of the sensor unit becomes easy, and the durability and operation stability of the sensor unit can be secured.

[Brief description of the 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 shown in FIG. 1. FIG. FIG. 4 is a partially cutaway sectional view taken in the direction of arrows XX. FIG. 4 is a detailed view of a voltage displacement meter. [Description of Signs of Main Parts] 1 Handle 2 Steering device 9 Actuator 13 Controller 14 Electric motor 26 Voltage displacement meter 50 Torque sensor assembly 14 Electric motor

Claims (1)

(57) [Claims] 1. A steering mechanism fixed to a vehicle body or the like operated by a steering operation, a link mechanism for turning wheels according to a steering amount of the steering mechanism, and a torque sensor assembly for detecting a steering torque. A motor that drives the link mechanism based on detection information from the torque sensor assembly to assist in turning the wheels, and a controller that controls the motor based on detection information from the torque sensor assembly. And the torque sensor assembly is integrally formed with the steering mechanism, and is fixedly fitted to an input shaft connected to the steering mechanism, and the input shaft is connected to the link via a ball nut. An electric power steering apparatus, wherein an output shaft connected to a mechanism is meshed, and the torque sensor assembly has a rotary sensor.