JPS63315373A - Control method for vehicle speed response type power steering apparatus - Google Patents

Abstract

PURPOSE:To make it possible to detect at once a failure of a vehicle speed sensor by determining breakage of the vehicle speed sensor when the governor hydraulic pressure of a automatic hydraulic transmission does not correspond to a vehicle speed indicated by the sensor. CONSTITUTION:A valve mechanism 9 for controlling the flow rate or pressure of hydraulic oil is controlled in accordance with an output signal from a control circuit 11 in response to a vehicle speed signal from a vehicle speed sensor 10. The control circuit 11 receives a signal from a governor hydraulic pressure sensor 13 for detecting the governor hydraulic pressure. Further, when a vehicle speed signal from the vehicle speed sensor 10 is zero, whether a signal from the governor hydraulic pressure sensor indicates a value greater than a predetermined value or not is checked. If the governor hydraulic pressure is greater than the predetermined value, it means that no vehicle speed signal is delivered from the vehicle speed sensor 10 although the vehicle is running, and accordingly, whether the vehicle speed sensor is failed or the wiring to the control circuit 11 is broken is determined, and a power assist mode adapted to applied to high speed running operation is turned on and an alarm is issued.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of controlling a vehicle speed responsive power steering device.

BACKGROUND ART In order to reduce the need for steering wheel operations during steering in automobiles, a torque sensor is provided to detect steering torque during steering operations, and the steering torque detected by the torque sensor is converted into an electrical quantity. The output of the electric motor is variably controlled according to changes in the amount of electricity, and the electric motor provides power assist in the steering direction according to the steering torque, and a vehicle speed sensor is provided to detect the vehicle speed. An electric power steering device that reduces the output of the electric motor according to the vehicle speed based on sensor signals to prevent excessive steering during high-speed driving has already been published [5f1 (for example, Japanese Patent Publication No. 1808/1983). reference).

Problems to be Solved by the Invention: In an electric power steering device like the one described in F, when driving at high speeds, the power assist becomes small and the steering force applied to the steering wheel increases, which prevents the steering wheel from being turned too much. If the signal from the vehicle speed sensor that reduces the output of the electric motor is not input due to sensor failure, etc., the same amount of power assist will be applied in the steering direction even when driving at high speeds as when driving at low speeds, which will cause the steering to be applied to the steering wheel. There is a problem of stagnation if the force becomes too light and the steering wheel is turned too much.

SUMMARY OF THE INVENTION An object of the present invention is to provide a control method for a vehicle speed-responsive power steering device that can address the above-mentioned problems.

Means for Solving the Problems The present invention provides a fluid automatic vehicle equipped with a vehicle speed-responsive power steering device that gradually reduces power assist in the steering direction as the vehicle speed indicated by a vehicle speed signal from a vehicle speed sensor increases. In a vehicle equipped with a transmission, when there is no correspondence between the governor oil pressure of the hydraulic automatic transmission, which changes depending on the vehicle speed, and the vehicle speed indicated by the vehicle speed signal from the vehicle speed sensor, it is determined that the vehicle speed sensor is disconnected, and the system is applied when driving at high speed. This feature is characterized in that it switches to a small power assist mode and also issues an alarm.

According to ``Function'', even if the vehicle speed sensor fails during high-speed driving, not only can the failure of the vehicle speed sensor be detected immediately, but also a large power assist is not applied as in the case of stationary steering. It is possible to prevent problems such as excessive turning of the steering wheel.

Example The present invention will be explained below with reference to the accompanying drawings.

In FIG. 1, 1 is an engine (not shown) or '11!
This is a hydraulic pump driven by a drive source such as a dynamic motor, and the hydraulic oil discharged by the hydraulic pump 1 flows through an orifice 2 and a high-pressure pipe 3 to a control valve 4 section, and is closed to the control valve except during steering. The oil circulates from part 4 through low-pressure piping 5 to reserve tank 6, and during steering, control valve 4 is activated and the working oil from high-pressure piping 3 enters either the R or L working chamber of the cylinder device (not shown). A force is applied to the rack shaft via the piston in the operating direction of the steering device, thereby reducing the steering force. 7 is a relief valve.

8 is a drain path leading from the high pressure pipe 3 to the reserve tank 6; 9 is a valve mechanism that variably controls the passage area of the drain path 8; the valve mechanism 9 is connected to a control circuit 11 based on a vehicle speed signal from a vehicle speed sensor Controlled by output signal. 12 is an orifice provided in the drain path 8.

That is, when the vehicle speed signal from the vehicle speed sensor 10 indicates a low vehicle speed, the valve mechanism 9 closes the drain passage 8, and all the working oil discharged from the hydraulic pump 1 flows to the control valve 4 section to reach the maximum level. As the vehicle speed increases, the valve mechanism 9 gradually increases the passage area of the drain passage 8, and the amount of drain from the high-pressure pipe 3 to the reserve tank 6 gradually increases, so that the operating oil to the control valve 4 section increases. The amount can be reduced and the puff assist can be made small.

The control gIl aspect of the vehicle speed responsive power steering as described above is well known as described above, and therefore detailed explanation will be omitted.

In the known control J of the vehicle speed responsive power steering device as described above, the lj speed sensor 10 for detecting the vehicle speed is used.
When a speedometer installed in a car is used, a failure in the speedometer itself or a break in the speedometer cable can be confirmed from the speedometer display. When a fault such as a break in the wiring occurs, the control circuit 11
Since the system judges that the vehicle is at city speed or zero and controls the vehicle, the power assist is maximized and the steering force becomes too light even when driving at high speed, which may cause excessive steering. There is.

Therefore, in the present invention, we have focused on the fact that the governor hydraulic pressure used to perform automatic gear shifting in a vehicle equipped with a hydraulic automatic transmission has a characteristic of gradually increasing according to the vehicle speed as shown in FIG. Oil pressure and vehicle speed sensor 1
It detects whether the vehicle speed indicated by the vehicle speed signal from 0 corresponds to the vehicle speed, and if they do not correspond, it is determined that the vehicle speed sensor 10 has failed, and the system switches to a small power assist that is applied when driving at high speed. It was designed to send out information.

That is, the governor oil pressure signal of the governor oil pressure sensor 13 which detects the governor oil pressure and issues the governor oil pressure signal is input to the control circuit 11, and the governor oil pressure signal is inputted to the control circuit 11 at a certain period, for example, 0.3.
Every second, as shown in FIG. 3, it is checked whether the vehicle speed indicated by the vehicle speed signal from the vehicle speed sensor 10 is zero, and if it is 0, the governor oil pressure indicated by the governor oil pressure signal from the governor oil pressure sensor 13 is at a predetermined value. For example, it is checked to see if it is greater than or equal to I Kg/cm2, and if it is greater than the predetermined value, it means that there is no input of the vehicle speed signal from the vehicle speed sensor 10 even though the vehicle is running, indicating that the vehicle speed sensor IO is malfunctioning. It is determined that the wiring from the vehicle speed sensor 10 to the control circuit 11 has broken, and the system switches to a small power assist mode applied during high-speed driving and issues a notification.

Note that normal power assist is provided during normal driving when a vehicle speed signal is input from the vehicle speed sensor 10 and when stopped when a vehicle speed signal is not output from the vehicle speed sensor 10 and a governor oil pressure signal is not output from the governor oil pressure sensor 13. Needless to say.

Also, as a method to check the correspondence between vehicle speed and governor oil pressure,
A method may be used to compare the vehicle speed and the governor oil pressure, and for example, it may be determined that the vehicle speed sensor has failed when the vehicle speed and the governor oil pressure deviate from the correspondence shown in FIG. 2 by a predetermined value or more.

Effects of the Invention As described above, according to the present invention, there is provided a fluid control system equipped with a vehicle speed-responsive power steering device that gradually reduces power assist in the steering direction as the vehicle speed indicated by the vehicle speed signal from the vehicle speed sensor increases. In a vehicle with an automatic transmission, when there is no correspondence between the governor oil pressure of the hydraulic automatic transmission, which changes depending on the vehicle speed, and the vehicle speed indicated by the vehicle speed signal from the vehicle speed sensor, it is determined that the vehicle speed sensor is disconnected, and when driving at high speed. By switching to a small power assist that is applied and issuing a warning, even if the vehicle speed sensor fails while driving, it is not only possible to detect the failure immediately, but also to prevent large Since power assist is not applied, it is possible to prevent problems such as turning the steering wheel too much.
This can bring about great practical effects.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating an embodiment of the present invention, FIG. 2 is a governor oil pressure characteristic diagram with respect to vehicle speed, and FIG. 3 is a flowchart illustrating an embodiment of the present invention. ■... Hydraulic pump, 3... High pressure piping, 4... Control valve, 5... Low pressure piping, 6... Reserve tank, 8... Drain path, 9... Valve mechanism, 10・
...Vehicle speed sensor, 11...Control circuit, 13...Governor oil pressure sensor. that's all

Claims (1)

[Claims] In a vehicle equipped with a fluid automatic transmission equipped with a vehicle speed-responsive power steering device that gradually reduces power assist in the steering direction as the vehicle speed indicated by a vehicle speed signal from a vehicle speed sensor increases, the power assist changes depending on the vehicle speed. When there is no correspondence between the governor oil pressure of the fluid automatic transmission and the vehicle speed indicated by the vehicle speed signal from the vehicle speed sensor, it is determined that the vehicle speed sensor is disconnected, and the system switches to a small power assist mode applied during high-speed driving and issues a warning. A method for controlling a vehicle speed responsive power steering device, characterized in that: