JPH0232542Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a power steering device that changes power assist according to steering load.

Power steering, which uses hydraulic power to assist, is widely used to reduce steering effort, but since the steering load is approximately proportional to vehicle speed, power assist at high speeds actually reduces steering stability. In order to prevent this, a system has been proposed in which the flow rate of hydraulic oil supplied to the power cylinder is reduced according to the vehicle speed.

However, conventionally, vehicle speed has been detected by electrically or mechanically detecting the rotation speed of the propeller shaft, resulting in problems such as long wiring to the power cylinder and a complicated structure. It was hot.

It is an object of the present invention to provide a power steering device with a simple configuration that eliminates such conventional problems.

To this end, the present invention provides a power steering system that includes a variable orifice in the middle of the circuit that supplies pressure oil from the pump to the power cylinder and a valve that returns excess oil to the reservoir. A control circuit is provided that calculates a steering load by integrating acceleration and narrows down the variable orifice in accordance with a decrease in the steering load.

In the present invention, since the traveling speed representing the steering load is calculated only by the acceleration detection means, the configuration of the control system of the power steering device is significantly simplified.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

In FIG. 1, reference numeral 10 denotes an acceleration detection means whose output increases in accordance with the acceleration of the vehicle, and is constituted by a known acceleration sensor.

Reference numeral 3 denotes a control circuit consisting of an integrator, an amplifier, etc., which integrates the output of the acceleration detecting means 10 to calculate the vehicle speed, which is a representative value of the steering load, and outputs a signal current that increases as the vehicle speed increases. Output to solenoid 4.

The solenoid 4 increases or decreases the opening degree of the variable orifice 5, and the flow rate is reduced as the exciting current increases.

This variable orifice 5 supplies pressure oil from a pump 6 to a power cylinder 7 via a switching valve (not shown).
It is inserted in the middle of the circuit that sends it to.

The pressure difference between the front and rear of the variable orifice 5 is kept almost constant by the flow control valve 8 which returns excess oil to the reservoir in response to the pressure difference between the front and rear of the variable orifice 5.

Therefore, the flow rate passing through the variable orifice 5 becomes exactly proportional to the opening degree of the orifice.

In the above configuration, when the vehicle accelerates and the vehicle speed increases, the increase in vehicle speed is reflected by the acceleration detection means 10.
It is calculated by the control circuit 3 as an integral value of the acceleration through the . On the other hand, the vehicle speed when the vehicle is not accelerating is obtained from the acceleration progress up to that point.

Based on this integral calculation, the control circuit increases the excitation current to the solenoid 4 as the vehicle speed increases.

Therefore, the variable orifice 5 is narrowed down via the solenoid 4 in response to a reduction in the steering load, and the flow rate supplied to the power cylinder 7 can be reduced.

Generally, as the vehicle speed increases, the steering load decreases, and by preventing excessive power assist in high-speed ranges, steering stability can be improved.

Although the flow control valve 8 is provided in the above embodiment, the present invention can be applied to various other types.

As described above, according to the present invention, the steering load is calculated based on the acceleration of the vehicle, and the amount of oil supplied to the power cylinder is reduced in accordance with the decrease in the steering load. Power assist improves steering stability, and the effect is that such functions can be realized with an extremely simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an embodiment of the present invention. 3... Control circuit, 4... Solenoid, 5... Variable orifice, 6... Pump, 7... Power cylinder, 8... Flow control valve, 10...
...Acceleration detection means.

Claims (1)

[Scope of utility model registration request] In power steering, a variable orifice is installed in the middle of a circuit that supplies pressure oil from a pump to a power cylinder, and a valve is installed to return excess oil to a reservoir.In power steering, a means for detecting acceleration and an integral of the detected acceleration are used to reduce the steering load. A power steering device comprising a control circuit that performs calculations and narrows down the variable orifice according to a decrease in steering load.