JPH10244952A - Electric power steering unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the restoring force at the slewing motion, and to judge the slewing angle and the returning quantity, by comprising a means for operating the first and second motor driving signals, and determining the third motor driving signal by comparing the first and second driving signals, for driving a motor. SOLUTION: A steering torque signal added to a steering handle 2 is read, and a chopper ratio D1 of a motor 12 is operated. The chopper ratio D1 is set in such manner that it is agreed with a direction of the steering torque, and is almost proportional to the magnitude of the same. Then the rotation angular speed at the present time, of the fork lift is read, and the chopper ratio D2 of the motor 12 which is determined by this angular speed, is operated. The chopper ratio D2 is set in such manner that the direction is opposite to that of the steering ring, and the chopper ratio D2 is almost proportional to the rotation angular speed. Then the chopper ratios D1 and D2 are added to determine the chopper ratio D3 by which the motor 12 is finally driven. Whereby the restoring force can be obtained, and the judgement on the steering can be performed.

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 used for a steering device of a vehicle and supplying an assist torque to a steering wheel.

[0002]

2. Description of the Related Art A steering device used in a vehicle can steer a steered wheel by an operator steering a steering handle. However, in recent technology, a steering device according to the magnitude and direction of a steering torque applied to the steering handle is controlled. The electric power steering motor is driven to reduce the steering force for the operator to steer the steering wheel.

That is, the direction of rotation of the steering motor is determined by the direction of the steering torque applied to the steering wheel, and the amount of rotation of the electric power steering motor is determined by the magnitude of the steering torque. The supply amount of assist torque for steering the vehicle was determined.

[0004]

However, in the above-described configuration, it is not possible to obtain the restoring force of the steering handle at the time of turning, for example, in a vehicle not equipped with a power steering device.

Therefore, the operator cannot sense the turning angle or turning direction of the vehicle at the time of turning by the tactile sensation applied to the steering, and the current turning angle of the vehicle or the steering wheel at the time of changing the vehicle from turning to straight traveling. Driving was difficult because the amount returned was unknown.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object the restoration of a steering handle at the time of turning as well as a vehicle equipped with an electric power steering device. An object of the present invention is to provide an electric power steering device capable of obtaining a force and determining a turning angle of a vehicle body, an amount of return of a steering, and the like.

[0007]

According to the present invention, there is provided a steering torque detector capable of detecting the magnitude and direction of a steering torque applied to a steering handle, and a power arranged to supply an assist torque to a steered wheel. A steering motor, a control device that rotationally drives the power steering motor, a rotational angular speed detector that can detect a rotational angular speed of the vehicle body, and a steering direction detector that detects a steering direction of a steered wheel, wherein the control device includes: Means for calculating a first motor drive signal corresponding to the direction of the torque signal obtained by the steering torque detector and corresponding to the magnitude thereof; and calculating the angular velocity obtained by the rotational angular velocity detector. A second motor that can rotate the power steering motor in a direction opposite to the direction of the steered wheels obtained by the steering direction detector according to the size. Means for calculating a drive signal; and means for comparing the first motor drive signal and the second motor drive signal to determine a third motor drive signal. The power steering motor is driven by the determined third motor drive signal.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described as an example of a vehicle employed in a reach-type forklift. As shown in FIG. 6, the reach type forklift 1 includes a drive wheel 4 that can be steered by a steering handle 3 in a vehicle body 2.

[0009] As shown in FIG. 5, the drive wheel 4 is configured such that the steering torque applied to the steering handle 3 is transmitted from the sprocket 5 through the chain 6 to the sprocket 7.
, And the input shaft 8 fixed to the sprocket 7
The rotation is transmitted to the output shaft 10, the universal joint 11, the drive shaft 14, and the drive gear 15 via the steering torque detector 9 to rotate the turning gear 16.

A turning gear case 17 for pivotally supporting the drive wheel 4 is fixed to the turning gear 16.
The steering torque detector 9 includes an input shaft 8 and an output shaft 1.
A torsion relative to 0 is electrically detected as a steering torque signal, and the power steering motor 12 is rotationally driven by a motor drive signal corresponding thereto, and the assist torque is reduced via a gear case 13 having a built-in reduction mechanism. The steering torque is applied to the drive shaft 14 to reduce the steering torque. However, in the present invention, the power steering motor 12 is driven to rotate by using the motor drive signal as a chopper signal.

The turning gear 16 is provided with a steering direction detector 20 for detecting the steering direction of the drive wheel 4, for example, a micro switch.

Further, the vehicle body 2 of the reach type forklift 1
Is provided with a rotational angular velocity detector 18 to detect the rotational angle of the reach type forklift 1 per unit time, that is, the rotational angular velocity of the reach type forklift 1.

Next, a description will be given based on a block diagram of the control device of the present invention shown in FIG. From each of the rotational angular velocity detector 18, the steering torque detector 9, and the steering direction detector 20,
The rotational angular velocity signal of the reach type forklift 1 and the steering torque signal applied to the steering handle 3 are A / D
Input to the converter.

In the A / D converter, each input signal is converted from an analog signal to a digital signal, and is input to an MPU or a RAM via a bus line.

The ROM is a working memory. The ROM stores various motor drive signals for driving the power steering motor 12 which can be arbitrarily determined, the relationship between the steering torque and the rotational angular velocity, and the power steering motor 12. The operation procedure of the motor drive signal for driving the motor is stored.
This will be described later.

The chopper ratio of the power steering motor 12 determined by the MPU is converted into an analog signal by a D / A converter, and drives the power steering motor 12 via a logic circuit 19. Note that a control signal is input from the MPU to the logic circuit 19, and control such as normal rotation and reverse rotation of the power steering motor 12 is performed.

FIG. 1 is a flowchart showing a processing procedure of the present invention. First, a steering torque signal applied to the steering handle 3 is read (S1), and a chopper ratio D1 of the power steering motor 12 is calculated (S1).
2).

The chopper ratio D1 can be derived from a graph as shown in FIG. 4, and the relationship between the chopper ratio D1 as shown in FIG. 4 and the steering torque is stored in the ROM. Therefore, the MPU can calculate the chopper ratio D1 corresponding to the steering torque.

The chopper ratio D1 is such that the direction of the steering torque obtained by the steering torque detector 9, that is, if the steering handle 3 rotates clockwise, the power steering motor 12 also rotates clockwise in the same direction. And it is set so as to be substantially proportional to the steering torque.

If the steering torque is equal to or greater than a predetermined value, the absolute value of the chopper ratio D1 is at most 100%. If the absolute value of the steering torque is equal to or less than the predetermined value, hunting of the power steering motor 12 is prevented. Chopper ratio D1
Is set to zero. The chopper ratio for rotating the power steering motor 12 clockwise is given a positive sign, and the chopper ratio for rotating the power steering motor 12 counterclockwise is given a minus sign.

Next, the MPU reads the current rotational angular velocity of the reach type forklift 1 (S3), and calculates a chopper ratio D2 of the power steering motor 12 determined by the angular velocity (S4).

The chopper ratio D2 regulates the steering restoring force for rotating the steering handle 3 in the reverse direction among the chopper ratios for driving the power steering motor 12. This will be described with reference to FIG.

The horizontal axis indicates the rotational angular velocity of the reach type forklift 1, and the vertical axis indicates the chopper ratio D2 of the power steering motor 12.

The chopper ratio D2 is a direction opposite to the direction of the drive wheel 4 obtained by the steering direction detector 20,
The rotation angular velocity is set to be substantially proportional to the rotational angular velocity obtained by the rotational angular velocity detector 18. That is, when the drive wheel 4 is in the right direction, the power steering motor 12 outputs a negative chopper rate so that the power steering motor 12 rotates counterclockwise. In this example, the chopper is -50% of the maximum value of the rotational angular velocity. The example which outputs a rate is illustrated.

Finally, the chopper rates D1 and D2 are added to finally determine the chopper rate D3 for driving the power steering motor 12. (S6).

For example, let us consider a state in which the steering angle is rotated clockwise from the neutral position and the drive wheel 4 is gradually approaching the right steering end while the vehicle body 2 is stopped. Here, since the steering torque is gradually increased, the chopper ratio D1 is proportionally increased from 0 to 100%. At this time, since the body part 2 is stopped, the rotation angular velocity is 0, and the chopper ratio D2 is also naturally 0, so that the final chopper ratio D3 is the chopper ratio D1.

Next, it is assumed that the steering angle is rotated rightward from the neutral position while the vehicle body 2 is running, and the drive wheel 4 is gradually approaching the right steering end. . Here, as described above, since the steering torque is gradually increased, the chopper ratio D1 is proportionally increased from 0 to 100%. At this time, since the vehicle body 2 is traveling, the rotational angular velocity also increases, and the chopper ratio D
2 also naturally increases from 0 to -50%, and thus the final chopper ratio D3 increases from 0 to 50% as the sum of the chopper ratio D1 and the chopper ratio D2 and is output.

When the vehicle body 2 is run without applying a steering torque while the steering handle 3 is rotated to the right by a certain angle, the chopper ratio D1 is 0, and the rotation angular speed increases, so that the chopper ratio is increased. Rate D2 is 0 to -50%
Changes to Therefore, since the chopper ratio D2 becomes the final chopper ratio D3, the steering handle 3 is configured to automatically return to the neutral position.

As a result, as the rotational angular velocity increases, the steering reaction force gradually acts on the human hand operating the steering handle 3, and the steering becomes heavier.
It increases linearly as it approaches the right steering end of the drive wheel 4.

Further, the steering handle 3 is automatically returned to the neutral position when the hand is released while the steering handle 3 is being rotated clockwise while the vehicle is running.

The above-described operation can be similarly performed when the steering handle 3 is rotated to the left.

Although the present invention has been described in detail above, the present invention is not limited to the above-described embodiment, but can be variously modified without departing from the gist of the present invention. It can be used for various body parts 2. Further, as an example of changing the chopper ratio, a linear curve is shown in this example, but it goes without saying that various other quadratic and cubic curves can be adopted.

[0033]

According to the present invention, as a result of employing the above configuration,
Even in a vehicle using an electric power steering device, it is possible to obtain the restoring force of the steering wheel at the time of turning, and the operator senses the turning angle and turning direction of the vehicle with the tactile sensation applied to the steering wheel, This makes it possible to determine the amount of return of the steering handle when changing the vehicle from turning to straight traveling.

[Brief description of the drawings]

FIG. 1 is a flowchart of the present invention.

FIG. 2 is a control block diagram of the present invention.

FIG. 3 is a diagram showing a relationship between an angular velocity and a chopper ratio D2 for driving a power steering motor.

FIG. 4 is a diagram showing a relationship between a steering torque and a chopper ratio D1 for driving a power steering motor.

FIG. 5 is a diagram for explaining a steering mechanism of a drive wheel.

FIG. 6 is a side view of the reach type forklift.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reach type forklift 2 Body part 3 Steering handle 4 Drive wheel 9 Steering torque detector 12 Power steering motor 18 Rotation angular velocity detector 20 Turning direction detector

Claims (1)

[Claims] 1. A steering torque detector capable of detecting a magnitude and a direction of a steering torque applied to a steering wheel, a power steering motor arranged to supply an assist torque to a steered wheel, and the power steering motor. A control device that rotationally drives the vehicle, a rotational angular velocity detector that can detect a rotational angular velocity of the vehicle body, and a steering direction detector that detects a steering direction of a steered wheel, wherein the control device is obtained by the steering torque detector. Means for calculating a first motor drive signal corresponding to the direction of the detected torque signal and according to the magnitude of the torque signal; and the steering direction according to the magnitude of the angular velocity obtained by the rotational angular velocity detector. In the direction opposite to the direction of the steered wheels obtained by the detector,
A second power steering motor capable of rotationally driving the motor;
Means for calculating the motor drive signal, and comparing the first motor drive signal with the second motor drive signal to obtain a third motor drive signal.
Means for determining the motor drive signal of the above, wherein the power steering motor is driven by the third motor drive signal determined thereby.