JPH0674048B2 - Steering angle sensor for vehicle - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering angle sensor used in an electric power steering device for an automobile.

2. Description of the Related Art In an electric power steering system for an automobile, a torque detector, a steering wheel position detector, and a steering torque applied manually are added to solve the problem that the steering handle returns due to the moment of inertia of the electric motor. A discriminator is provided that outputs no output while the steering torque is zero and the steering wheel is in a position other than the neutral position while the output is switched to the electric motor and the electric motor is switched at the same time. By applying a voltage through a voltage limiting resistor to rotate the electric motor in the steering wheel return direction, the moment of inertia of the electric motor is prevented from being applied to the steering wheel during the hand-release operation, and the steering wheel restores force from the wheels. A device that can return to the neutral position by itself has already been developed.

In such an electric power steering device, as a steering wheel position detector that outputs a signal for rotating the electric motor in the steering wheel return direction, a movable element that is normally screw-fed with the rotation of the steering shaft, and the movable element slides. A switch mechanism composed of a moving left contact plate and a right contact plate is used, and both contact plates of the switch mechanism are provided in series with a gap of about the width of the mover.
The gap position is usually the same as the neutral position of the steering wheel (for example, Japanese Patent Publication No. 46).
-5168).

Problems to be Solved by the Invention Since the conventional steering wheel position detector as described above has an on / off control system, the steering wheel is rotated to the steering wheel return direction, which has been applied up to near the neutral position of the steering wheel. Since the steering wheel return force suddenly becomes zero at the neutral position, there is a problem that a strange feeling is likely to occur during steering.

It is an object of the present invention to provide a turning angle sensor that addresses the above conventional problems.

Means for Solving Problems According to the present invention, a steering wheel is steered from a neutral position to a maximum steering position on one of two members that relatively move in accordance with a steering operation in a steering device. The two driving magnets having a length almost equal to the moving amount and having surfaces of different polarities are fixed together in the moving direction, and the other member is a magnetic element using a Hall element or a magnetoresistive element. The sensor moves in parallel relative to the surfaces of the two drive magnets as the one member moves, and also opposes the abutting portion of the two drive magnets when the steering handle is in the neutral position. The two drive magnets are mounted so as to be positioned so that the distance between the two drive magnets and the magnetic sensor is the maximum on the butting side of the two drive magnets and the other side. It is characterized in that it is set to be gradually smaller toward.

Effect The present invention adopts the above-described configuration, and the absolute value of the output voltage of the steering angle sensor is substantially linear so that the absolute value of the output voltage of the steering angle sensor becomes minimum with the steering wheel in the neutral position and gradually increases as the steering angle increases. Along with the characteristic that changes, the polarity of the output voltage is reversed on the left and right with the neutral position as a boundary, and the steering handle return force controlled by the output voltage gradually changes toward zero as it approaches the neutral position. The feeling of strangeness in steering is completely eliminated.

Embodiment One embodiment of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, 1 is a steering handle, 2 is a steering shaft, 3 is an intermediate shaft, and 4 is a pinion. When the steering handle 1 is rotated, the pinion 4 is rotated through the steering shaft 2 and the intermediate shaft 3, and the steering is performed. The rack shaft 5, which is supported in the gear box 6 so as to be slidable in the axial direction, slides in the axial direction to steer the vehicle.

Reference numeral 7 is an electric motor, 8 is a speed reducer, and 9 is a pinion. The electric motor 7 is controlled by a signal from a torque sensor 10 that detects the torque of the pinion 4, and for example, the steering wheel 1 When the rotary operation is performed to the right, the sensor 10 which detects the rotational torque detects it and rotates the electric motor 7 to the right, and the pinion 9 rotates to the right through the speed reducer 8 to slide the rack shaft 5 in the steering direction. Then, the manual operation force from the steering handle 1 side is assisted by the input from the electric motor 7 side to reduce the manual operation force.

The steering angle sensor 11 that outputs a signal for rotating the electric motor 7 in the return direction is a magnetic sensor 12 fixed to one of the two members of the rack and pinion type steering device that move left and right relatively, for example, the steering gear box 6. And the other two, for example, two drive magnets fixed to the rack shaft 5.
It is composed of a combination of 13,14.

Magnetic sensor 12 using Hall element or magnetoresistive element
Is attached to the lower end surface of the magnetic sensor mounting base 12a fixed to the opening 6a provided in the steering gear box 6, that is, the surface facing the rack shaft 5. The axial outer peripheral surface of the rack shaft 5 facing the magnetic sensor 12 has a length substantially equal to the moving distance of the rack shaft 5 when the steering handle 1 is steered from the neutral position to the maximum steering position. The groove 5a is provided in both left and right directions centering on a point 5b facing the central point of the magnetic sensor 12 when the steering handle 1 is in the neutral position.

Drive magnets 13 and 14 each having a length of about half the axial length of the recess groove 5a are attached to the groove 5a so as to be aligned in the longitudinal direction, and the drive magnets 13 and 14 are respectively attached to the rack shaft 5. The lower part facing the bottom of the groove and the magnetic sensor 12
Is magnetized so as to have a different polarity from the upper surface opposed to, and the polarities are opposite in the drive magnets 13 and 14. That is, the upper surface of the drive magnet 13 facing the magnetic sensor 12 has an N pole, whereas the upper surface of the drive magnet 14 has an S pole.

The drive magnets 13 and 14 are both configured to have a minimum thickness on the side of the center point 5b in the axial length of the recessed groove 5a and gradually increase toward both ends of the recessed groove 5a.

According to the present invention, by adopting the above configuration, the steering handle 1 is set to the neutral position, and the magnetic sensor 12 is positioned to face the center point 5b in the axial length of the concave groove 5a, that is, the butting portion of the drive magnets 13 and 14. At this time, the distance between the magnetic sensor 12 and both drive magnets 13 and 14 becomes maximum, and at the same time, the magnetic fields due to the N pole on the upper surface of the drive magnet 13 and the S pole on the upper surface of the drive magnet 14 cancel each other, so that the output of the magnetic sensor 12 is zero. Becomes When the steering handle 1 is steered to the right or left from the neutral position, the distance between the magnetic sensor 12 and the upper surface of the drive magnet 13 or 14 facing it becomes gradually smaller as the stroke of the rack shaft 5 to the left and right increases. As a result, as shown in FIG. 3, the absolute value of the output voltage of the magnetic sensor 12 gradually increases, and the distance between the magnetic sensor 12 and the upper surface of the drive magnet 13 or 14 facing it becomes constant. When it becomes, the output voltage of the magnetic sensor 12 becomes a constant value and is saturated. Then, as shown in FIG. 3, the polarities of the output voltage of the magnetic sensor 12 are opposite between left turning and right turning.

As described above, in the left and right predetermined steering angle ranges centered on the neutral position of the steering wheel 1, the output voltage characteristic gradually changes to zero as it approaches the neutral position, and the output voltage characteristic is controlled by the output voltage. Electric motor 7
The return direction rotational force gradually approaches zero as it approaches the neutral position, and then becomes zero at the neutral position, so there is no sense of discomfort during steering.

Note that the size of the turning angle range, which is a characteristic that the output voltage of the magnetic sensor 12 changes substantially linearly, and the change rate of the output voltage with respect to the stroke amount of the rack shaft 5 in that range are as follows.
It can be arbitrarily set by changing the shape of the surface of the drive magnets 13 and 14 facing the magnetic sensor 12 or changing the relative positions of the magnetic sensor 12 and the drive magnets 13 and 14. Also, a slight gap may be provided in the abutting portion between the drive magnets 13 and 14 so that the output voltage of the magnetic sensor 12 is maintained at zero in the minute stroke range of the rack shaft 5 near the neutral position. .

FIG. 4 shows another embodiment of the present invention, in which the rack shaft 5
Magnetic sensor caused by bending or bending due to load
The change in the gap between the upper surface of the drive magnets 13 and 14 and the upper surface of the drive magnets 13 and 14 opposed thereto and the change in the output voltage of the magnetic sensor 12 due to the change are prevented.

That is, in FIG. 4, the surface of the drive magnets 13 and 14 facing the magnetic sensor 12 is filled with a filling material 5c such as a synthetic resin so that the surface of the rack shaft 5 is flush with the magnetic sensor. An urging spring 12b that attaches the magnetic sensor 12 to the magnetic sensor mounting base 12a so as to be slidable toward the surface of the rack shaft 5 and urges the magnetic sensor 12 to press the surface of the rack shaft 5.
Is provided, and the biasing spring 12b keeps the magnetic sensor 12 elastically in contact with the surface of the filling material 5c.

With this configuration, even when the rack shaft 5 is bent or bent, the magnetic sensor 12 always slides on the packing material 5c that is flush with the surface of the rack shaft 5, and the magnetic sensor The distance between 12 and the drive magnets 13 and 14 facing it will not change.

EFFECTS OF THE INVENTION As described above, according to the present invention, the steering handle is steered from the neutral position to the maximum steered position on either one of the two members that move relatively with the steering operation. Two driving magnets having a length almost equal to the moving amount and having surfaces with polarities different from each other were fixed by matching the moving directions, and a Hall element or a magnetoresistive element was used as the other member. The magnetic sensor is moved in parallel relative to the surfaces of the two drive magnets as the one member is moved, and is positioned opposite the butting portion of the drive magnets when the steering handle is in the neutral position. The two drive magnets are mounted so that the distance from the magnetic sensor is the maximum on the side of the butting portion of the two drive magnets, and the distance to the other side. The steering angle sensor for a vehicle is configured by a combination of the two drive magnets and a magnetic sensor.
The output characteristic of the steering angle sensor with respect to the movement amount of the two members that move to the right should be a change characteristic in which the polarities of the left and right sides of the steering handle are opposite to each other and gradually approach zero as they approach the neutral position. Therefore, the steering handle return force controlled by the output is gently reduced to zero as it approaches the neutral position, and a natural steering feeling without discomfort can be obtained. Further, as described above, the output angle of the steering angle sensor gradually changes to zero as it approaches the neutral position. It can be easily changed and set by changing the relative positions of the magnetic sensor and the drive magnet, etc., and in combination with the simple structure and high reliability, it can bring great effects in practical use. is there.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 1 is an overall external perspective view, FIG. 2 is a cross-sectional view of the main part, and FIG. 3 is an output voltage characteristic diagram of the magnetic sensor with respect to the rack shaft stroke amount. FIG. 4 is a sectional view of the main part showing another embodiment. 1 ... Steering handle, 2 ... Steering shaft, 5 ... Rack shaft, 6 ... Steering gear box, 10 ... Torque sensor, 11 ... Steering angle sensor, 12 ...
Magnetic sensor, 13, 14 ... Drive magnet.

Claims (2)

[Claims] 1. A movement amount when a steering handle is steered from either a neutral position to a maximum steering position to one of two members that relatively move in accordance with a steering operation in a steering device. Two driving magnets having lengths and surfaces having polarities different from each other are fixed in accordance with the moving directions, and the other member is provided with a magnetic sensor using a Hall element or a magnetoresistive element. 2 is moved so as to face the surfaces of the two drive magnets in parallel with each other, and when the steering handle is set to the neutral position, the two drive magnets are mounted so as to face the abutting portions of the two drive magnets. The distance between the driving magnets and the magnetic sensor is the maximum on the side of the butting portion of the two driving magnets, and becomes gradually smaller toward the other side. The vehicle turning angle sensor, characterized in that the set. 2. The magnetic sensor is biased so as to slide and press on a filling material such as a synthetic resin which is linearly filled on the surface of the driving magnet. The vehicle steering angle sensor according to the first aspect.