JPS59227560A - Power steering system - Google Patents

Abstract

PURPOSE:To achieve reliable assisting operation of steering system by controlling the driving force of an electromagnetic actuator for assisting the steering force through duty ratio control of power conduction to the actuator. CONSTITUTION:Upon rotation of a steering wheel, a sliding chip 11 is displaced from the central portion of a sliding resistor 10. Relays CR1 and CR2 in a steering direction signal producing means 13a are turned on respectively upon turning to the right and left. At the same time, said displacement signal is provided through an absolute level amplifier 13b to a car speed compensator 13c. This signal is amplified by a signal from a car speed pick-up sensor 14 with lower gain as the car speed increases and fed to a duty ratio control circuit 13e. The duty ratio control circuit 13 will function a motor drive circuit 13f if the input signal exceeds over the signal from a triangular wave oscillation circuit 13d. Consequently, a motor 9 is driven such that the steering operation is assisted to the right or left turn side through ON-state of said relay.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a power steering device used in automobiles, etc., and more particularly to an electric power steering device that applies steering assist force by electromagnetic means. .

(Prior Art) Many conventional power steering devices provide steering assist force using a power cylinder to which pressure oil is supplied by an oil pump. In such a hydraulically operated power steering device, in order to improve the responsiveness of the steering assist, the oil pump is driven at all times during vehicle operation, and when the steering assist force is unnecessary or can be small, the oil pump is operated at all times. A control valve installed in the hydraulic system between the oil pump and the power cylinder restricts the supply of pressure oil to the power cylinder.However, in this way, pressure oil is unnecessarily pumped by the oil pump,
It is obvious that a method of cutting part or all of the flow rate using a valve means increases the power loss of the engine and causes deterioration of fuel efficiency.

In order to eliminate these inconveniences, for example,
As shown in Publication No. 44.058, the steering assist force is applied by electromagnetic means such as a linear motor,
A so-called electric power steering device has been proposed in which the direction and magnitude of the current supplied to the electromagnetic means are controlled by a controller based on the rotational direction of the steering shaft and the steering force detected by a sensor. Since the electromagnetic means has better stand-up characteristics during driving than the hydraulic means mentioned above, in such an electric power steering device, the electromagnetic means can be stopped when the steering is not being carried out, thus saving energy. It is possible to do this.

However, with conventional electric power steering devices,
It has been recognized that vibrations from the electromagnetic means for steering assist are easily transmitted to the steering wheel via the steering shaft, resulting in an uneven steering feel.

(Object of the Invention) The present invention has been made in view of the above-mentioned circumstances, and provides an electric powered power steering system that makes it difficult for the vibrations of the electromagnetic means for steering assist to be transmitted to the steering wheel, thereby providing a sufficiently smooth steering feeling. Aiming to provide steering equipment
.

The target is

(Structure of the Invention) The power steering device of the present invention has a steering rotating shaft disposed coaxially with a steering shaft (for example, a worm shaft in a pole nut type steering device, a pinion in a rack and pinion type steering device, etc.). It is connected to a steering shaft via a torsion bar, and the steering assist force of an electromagnetic actuator is applied to this steering rotating shaft, and the steering direction and steering force are detected based on the torsional direction of the torsion bar. This is done by detecting the amount of torsion and torsion using the sensor, and in response to the output of this sensor, the control roller that controls the driving force and driving direction of the electromagnetic actuator receives the signal from the sensor and detects the torsion bar's torsion. a steering force signal generating means for outputting a steering force signal according to the amount of steering force, an oscillating means for oscillating a triangular wave, and an electromagnetic generator as the torsional force of the torsion bar increases in response to signals from the steering force signal generating means and the oscillating means. a duty ratio control means for controlling an actuator energization duty ratio so as to increase the amount of energization to the actuator; The present invention is characterized by comprising a direction signal generating means, and a driving means for outputting an actuator drive signal in response to signals from the duty ratio control means and the steering direction signal generating means.

(Effects of the Invention) As described in ``--, if an electromagnetic actuator is connected to the steering rotating shaft that is connected to the steering shaft via a torsion bar, the vibrations of this actuator are absorbed by the torsion bar. , the power is transmitted to the steering shaft, steering wheel, and steering wheel, resulting in a smoother steering feel. Furthermore, since the driving force of the electromagnetic actuator is controlled by controlling the duty ratio of the amount of current supplied to the actuator, operation is reliable.

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a power steering device according to one embodiment of the present invention. The device of this embodiment uses a ball nut type steering device as a basic steering device, and a worm shaft 3 is installed inside a pole nut 2 that is slidably arranged in the left and right directions in the figure in a steering gear box J. (rotary shaft for steering) is installed,
The worm shaft 3 and the pole nut 2 are screwed together through a large number of steel balls 4, and when the worm shaft 3 is rotated, the steel balls 4 are screwed into the threads around the shaft 3. The ball neck I-2 is moved in the axial direction. The pole nut 2 is provided with a rack 2a that meshes with the pinion 5a of the sector shaft 5. When the pole nut 2 is moved in the axial direction as shown in "2", the sector shaft 5 is rotated, and the sector shaft 5 is rotated. Connected steering member (not shown)
is moved to give a steering angle to the steered wheels.

``The worm shaft 3 is arranged coaxially with a steering shaft 6 that fixes a steering wheel (not shown), and inside the hollow portions formed at the tips of each of these shafts 3 and 6, there is a worm shaft 3.'' Version 7 is installed. This torsion bar 7 has a worm shaft 3 at each end thereof. It is fixed to the steering shaft 6 and connects both shafts 3 and 6. The worm shaft 3 is connected via a speed reducer 8 to a drive shaft (not shown) of an electric motor 9 serving as a steering assist electromagnetic actuator.

A sliding resistor 10 is fixed to the tip of the steering shaft 6, and the sliding resistor 10 is fixed to the worm shaft 3.
A slider 11 that contacts is fixed. The sliding resistor 10 and the slider 11 constitute a sensor J2 that detects the rotational direction and steering force of the steering shaft 6 as described later. The motor 9 rotates while the rotational force in the rotational direction 9 is controlled by the drive signal S3 which is also output from the controller 13.

The controller 13 will be explained in detail below with reference to FIG. The controller 13 includes a relay control circuit 132 as a steering direction signal generation means, an absolute value increaser 13b as a steering force signal generation means, a vehicle speed compensation circuit 13c, and a triangular wave oscillation circuit 1, each of which is supplied with power from a power supply circuit 23.
3d, a duty ratio control circuit 13e, and a motor drive circuit 13f. The output S1 of the sensor 12 is input to a relay control circuit 13a and an absolute value amplifier J31. The sensor 2 is supplied with power from the power supply circuit 23, and the sliding resistor 10 is supplied with +15V and -15V, for example, at both ends.
A potential of 15V is applied, and when no steering operation is performed, the slider 11 is in contact with the center of the sliding resistor 10, but when the steering wheel is rotated, the steering shaft 6 is rotated. As the steering shaft 6 twists the torsion bar 7 and rotates relative to the worm shaft 3, the slider 1
1 is the sliding resistance] 0 is displaced from the center. Therefore, if this slider 11 is connected to the comparator 20 of the relay control circuit 13a, the comparator 20 will be connected to the third
As shown in the figure, an external output eQl is generated. Therefore, when turning to the right, relay CR+ is turned on, while when turning to the left, relay CR,2 is turned on. When the vehicle is not being steered, both relays CIL+ and CTL2 are turned OFF.

On the other hand, when a steering operation is performed as described above, for example, if a larger steering force is applied because the vehicle speed is low or the steering speed is high, the steering shaft 6
rotates relatively to the worm shaft 3 while twisting the torsion bar 7 to a greater extent. Therefore Sessa]2
, the larger the steering force, the higher the absolute value of the potential output. When this output is passed through the absolute value amplifier 13b, the output e02' as shown in FIG.
02' is obtained. This output eo2' is input to the vehicle speed compensation circuit 13c.

In the vehicle speed compensation circuit t3cVC, the pulse signal input from the vehicle speed pickup processor J4 is converted into a voltage signal corresponding to the vehicle speed by the F-V converter 15, and the voltage signal is sent to the gate of the FET 17 through the amplifier 16. is applied to

Amplifier J8 is the output e O2 of the absolute value amplifier 131).
The gain is controlled by the voltage applied to F17, and the output e02' is amplified at a lower gain 41 as the vehicle speed increases.

The output eo2 of this amplifier 18 is input to the comparator 21 of the duty ratio control circuit 13e.

At the same time, this comparator 21 includes a triangular wave oscillation circuit 13.
The comparator 2J compares this triangular wave signal e03 with the output co2 of the up 18. While the output e()2 of this amplifier 18 exceeds the triangular wave signal e03,
The comparator 21 outputs a pulse signal Q.

This pulse signal qQ is input to the power transistor 22, and the power transistor 22 receives this signal Q and outputs an output voltage.
becomes N (see Figure 5).

At this time, if the steering wheel is turned off to the right, relay CR+ is ON as described above, so the current of battery power source E is
The field of the motor 9 flows along the path F→C1 (1), and the motor 9 rotates the worm shaft 3 via the reducer 8 in the direction of rotation during right turn steering, thereby assisting the steering operation. On the other hand, when the vehicle is steered to the left turning side, relay CR2 is turned on, so the current of battery power supply I is changed to armature A-) CI (2→field F- of motor 9) CR2 of motor 9. The direction of the current flowing through the field F is opposite to that in the above case. Therefore, the motor 9 rotates the worm shaft 3 in the opposite direction to that in the above case, thereby assisting the steering operation for turning left.

As mentioned above, power is supplied to the motor 9 only while the pulse signal Q is being output from the comparator 21, but since the period of the pulse signal Q is constant (the period of the triangular wave signal e03), the power is supplied to the motor 9. The amount of power supplied is controlled by the tuteity ratio according to the pulse width T of the pulse signal Q (see FIG. 5). This pulse width T becomes thicker as the level of the output e02 of the amplifier 18 is higher, that is, as the steering force is larger (therefore, the motor 9 is supplied with power at a higher duty ratio as the steering force is larger). The tab motor 9 generates a large rotational force as the steering force increases, and provides a large steering assist force to the steering device, thereby reliably reducing the steering burden on the driver.

Further, as mentioned above, the output e02 of the amplifier 18 becomes lower as the vehicle speed increases, so the duty ratio of the power supply to the motor 9 decreases. This reduces the risk of the steering being too light and jerky at high speeds.

In the above power steering device, the steering assist force is provided by the electric motor 9, and during steering, this motor 9 is driven and vibrations are likely to occur (note that this vibration is caused by the duty ratio control of the motor 9). (This is more likely to occur because the However, since the worm shaft 3 rotated by the motor 9 is partially connected to the steering shaft 6 via the torsion bar 7, the drive of the motor 9 is absorbed by the torsion bar 7 and the steering shaft 6 is Therefore, the steering feeling of this device is sufficiently smooth.

The embodiments in which the present invention is applied to a pole nut type steering device have been described above, but the present invention can also be applied to other steering devices. For example, the present invention can be applied to a rack and pinion type steering device. Alternatively, a pinion serving as a rotating shaft for steering may be connected to a steering shaft via a torsion bar, and this pinion may be assisted by an electromagnetic actuator.

Further, the electromagnetic actuator that generates one steering force is not limited to the motor in the above embodiment, but a known one such as a solenoid device may be selected and used.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway side view showing one embodiment of the present invention, Fig. 2 is a schematic circuit diagram of the controller in the above embodiment, and Figs. 3, 4, and 5 are graphs showing electrical signals in the controller. It is. 3. Worm shaft (rotating shaft for steering) 6. Steering shaft 7.. 1. - John bar 9... Electric motor 12... Sensor 13... Controller 13a... Relay control circuit (steering direction signal generation means)
J31)...absolute value amplifier (steering force signal generation means)]
3d...Triangular wave oscillation circuit 13e Duct 1
] Karikaji 13f...Motor drive circuit Figure 1 Figure 2

Claims (1)

[Claims] A steering shaft rotated by a steering wheel, an electromagnetic actuator that applies a steering assist force to a steering rotating shaft connected to the steering shaft via a torsion bar, a processor that detects torsion of the torsion bar, and a processor that detects twisting of the torsion bar. The output is received from a controller that controls the driving force and driving direction of the electromagnetic actuator according to the torsion of the torsion bar, and the controller receives the signal from the sensor and controls the amount of torsion of the torsion bar. Steering force signal generation means for outputting a steering force signal, oscillation means for oscillating a triangular wave, and in response to signals from the above-mentioned steering force signal generation means and oscillation means, the torsion force of the torsion bar becomes thicker (the more the torsion force is applied to the electromagnetic actuator). duty ratio control means for controlling the actuator energization duty ratio so as to increase the energization amount;
Steering direction signal generating means receives the control signal and outputs a steering direction signal in the same direction as the torsional direction of the torsion bar, and receives signals from the duty ratio control means and the steering direction signal generating means to generate an actuator drive signal. A power steering device comprising a driving means for outputting an output.