JPH0328081A - Four-wheel steering device - Google Patents

Abstract

PURPOSE:To enhance the response in sensing the steering angle speed of a steering wheel by controlling the operation of an opposite phase steering output generating mechanism in accordance with a steering angle speed signal given by a differentiating circuit consisting of an analog circuitry. CONSTITUTION:Through a cylinder the front wheels 1 are steered from a steering wheel 10, and a same-phase control valve 98 uses this steering oil presence as a pilot pressure and supplies one oil chamber of a rear power cylinder 90 with a same-phase steering force oil pressure. Meantime a controller 126 differentiates an analog signal given by a steering angle sensor 128 by the use of an analog type differentiating circuitry, obtains the steering angle speed, A/D converts, supplies a control signal to an opposite phase control valve 100 on the basis of the result therefrom and a signal given by a car speed sensor 127, applies the opposite phase steering force oil pressure to the other oil chamber of the rear power cylinder 90, and steers the rear wheels 82 with synthetization of the same-phase and opposite phase steering forces. This enhances the response in sensing the steering angle speed and enables effective performance of the phase inversion control.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement of a four-wheel steering device that steers front wheels and rear wheels.

(Prior art) Conventionally, it has been known that four-wheel steering systems can improve steering stability during vehicle turns by steering the rear wheels in the same phase as the front wheels. A four-wheel steering system has been proposed that simultaneously improves the yaw response when the vehicle turns by adding control for steering the wheels in the opposite phase direction to the above-mentioned in-phase control.

As such a four-wheel steering device, for example, Japanese Patent Application Laid-Open No. 59-1999
-1 8 6 7 7 3 publication and JP-A-62-191
There is a method disclosed in Japanese Patent No. 272, and in all of these, the rear wheel steering mechanism is controlled by the output of a single rear wheel steering means, and after the rear wheels are steered in the opposite phase direction at the initial stage of steering, the rear wheel steering mechanism is controlled by the output of a single rear wheel steering means. The wheels are steered in the same phase direction.

However, since the above-mentioned conventional example performs phase inversion control of the rear wheels using the output of a single rear wheel steering means, there is a drawback that the control becomes complicated.

Moreover, in the former conventional example, the phase of the rear wheels is reversed from opposite phase to in-phase after the initial set time of steering has elapsed, so it is difficult to set such a set time when considering both turning performance and convergence. .

Furthermore, in the latter conventional example, the phase of the rear wheels is reversed by detecting when the steering wheel is turned and when the steering wheel is turned. Since the rotation is reversed, the turning behavior of the vehicle changes rapidly, which tends to give a sense of discomfort to the occupants.

For this reason, the applicant filed a patent application for
No. 53 or the like, the in-phase steering means steers the rear wheels in the same phase direction as the front wheels in response to the steering angle or steering force of the steering wheel, and the in-phase steering means steers the rear wheels in the opposite phase direction from the front wheels in accordance with the steering angular velocity of the steering wheel. A four-wheel steering system has been proposed, which has a reverse phase steering means for steering in the direction of the vehicle, and controls the steering angle of the rear wheels by combining the steering output of the in-phase steering means and the steering output of the reverse phase steering means.

According to the four-wheel steering system proposed by the present applicant, phase reversal control of the rear wheels can be performed with relatively simple control, and it is possible to achieve both turning performance and convergence performance when the vehicle turns, and also to provide a suitable turning feeling. can be obtained.

(Problem to be Solved by the Invention) However, in the above four-wheel steering device proposed by the present applicant, the steering output of the rear wheels is determined by combining the steering output of the in-phase steering means and the steering output of the anti-phase steering means. Therefore, in order to efficiently achieve phase reversal control in which the rear wheels are once steered in the opposite direction at the beginning of steering, and then the rear wheels are steered in the in-phase direction, it is necessary to control the in-phase steering means at the beginning of steering. It is necessary to generate the steering output of the anti-phase steering means earlier than the steering output of , and it is required to improve the detection responsiveness of the steering angular velocity of the steering wheel.

For example, if a method in which the steering angular velocity is calculated from the steering angle signal using a calculation function in a microcomputer is used to control the above-mentioned anti-phase steering system, a big problem will arise in the operational response of the anti-phase steering system. Even if a steering angular velocity sensor according to the above formula is used, there is a problem in the resolution of calculation of the steering angular velocity, and the detection accuracy of the steering angular velocity deteriorates, and the responsiveness is not satisfactory.

(Means for Solving the Problems) The present invention was devised to solve the above problems, and the present invention steers the rear wheels in the same phase direction as the front wheels in response to the steering angle or steering force of the steering wheel. It has an in-phase steering means and an anti-phase steering means for steering the rear wheels in a direction opposite to the front wheels according to the steering angular velocity of the steering wheel, and the steering output of the in-phase steering means and the anti-phase steering means In a four-wheel steering system that controls the steering angle of the rear wheels by combining steering outputs, the anti-phase steering means includes an analog steering angle sensor that detects the steering angle of the steering wheel, and a system that differentiates the output of the steering angle sensor. a differentiator circuit that outputs a steering angular velocity signal, a reverse phase steering output generation mechanism that generates a steering output for the reverse phase steering, and a reverse phase steering output generating mechanism that receives the steering angular velocity signal output from the differentiator circuit and outputs the reverse phase steering output. The four-wheel steering device is characterized in that it includes a control device that controls the operation of the generating mechanism, and that the differential circuit is constituted by an analog circuit.

(Function) According to the present invention, a steering angular velocity signal is generated by differentiating the output of an analog steering angle sensor by a differentiating circuit constituted by an analog circuit, and a steering angular velocity signal is generated for anti-phase steering in accordance with this steering angular velocity signal. Since the output generation is controlled, the detection response of the steering angular velocity of the steering wheel is improved, and the operational response of the anti-phase steering system is improved.

(Example) Hereinafter, an example of the present invention will be described in detail based on the accompanying drawings.

1 to 19 show a first embodiment of the present invention.

FIG. 1 is a schematic diagram of this four-wheel steering system.

The left and right front wheels 1L and IR are rotatably supported by knuckles 2L and 2R. Also, knuckle 2L. 2R is connected to the power steering device 4 via tie rods 3L and 3R.
are connected to the left and right ends of the piston rod 5. The piston rod 5 is provided by passing through the cylinder 6, and the piston rod 5 is inserted into the cylinder 6 to form left and right pressure chambers 7L. It has a piston 8 spaced apart from each other by 7R. In addition, the piston rod 5
has a rack that engages with a pin pin 39 in the steering gear box 9. A first steering shaft 12 that receives steering input from the steering wheel 10 from a column shaft 11, and a steering gear box 9.
A variable gear ratio mechanism l4 is interposed between the second steering shaft 13 and the second steering shaft 13 connected to the second steering shaft 13. Therefore, the steering input from the steering wheel 10 is transmitted to the steering gear box 9 via the variable gear ratio mechanism 14. Further, a power steering valve known per se is provided between the second steering shaft 13 and the pinion gear 39, and the pressure chamber 7L.
It controls the supply of hydraulic pressure to 7R. In addition, the oil pump l5 for the power steering device 4 is
A type of pump that is driven by the engine 16 and whose discharge flow rate decreases as the engine speed increases after the engine speed reaches a predetermined value or higher is used.

Claims (1)

[Claims] In-phase steering means that steers the rear wheels in the same phase direction as the front wheels in response to the steering angle or steering force of the steering wheel; and phase steering means;
In the four-wheel steering device that controls the steering angle of the rear wheels by combining the steering output of the in-phase steering means and the steering output of the anti-phase steering means, the anti-phase steering means is an analog type that detects the steering angle of the steering wheel. a steering angle sensor, a differentiating circuit that differentiates the output of the steering angle sensor and outputs a steering angular velocity signal, an anti-phase steering output generation mechanism that generates a steering output for the anti-phase steering, and an output from the differentiating circuit. and a control device for controlling the operation of the anti-phase steering output generation mechanism in response to a steering angular velocity signal, wherein the differentiating circuit is constituted by an analog circuit.