JPS61115775A - Power steering system controller - Google Patents

Abstract

PURPOSE:To prevent production of noise and heat from a relief valve by contacting a pressure sensor against a piston of power cylinder or integral portion and detecting the steering end. CONSTITUTION:A microprocessor 41 is connected with pressure sensors 50, 51. Said sensors 50, 51 are employing pressurized conductive rubber 51' where fine nickel particles are mixed into silicon rubber as the switch body which is sandwitched by flat braid wire electrodes 54 then applied with silicon rubber 55. Then pressure is applied from the outside to approach fine nickel particles thus to vary the resistance and to flow current. Said pressure sensors 50, 51 are fixed to the cylinder end screwed to the end sections of power cylinder 13 and the gear housing 11 while surrounding the steering rod 14 and arranged to contact against the ball couplings 15, 16 as the piston 17 slides.

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a control device for a power steering device that prevents the generation of abnormal noise and the sudden increase in engine load at the end of steering.

<Prior art> Generally, in a vehicle equipped with a power steering device, a steering torque is applied to the steering wheel to rotate a servo valve, thereby supplying and discharging pressurized fluid from a pump to and from a power cylinder. The assist force allows for nimble steering operation.

<Problems to be Solved by the Invention> In such a conventional device, when the piston reaches the stroke end by steering the steering wheel to the steering end, the pump pressure increases to the relief pressure, which causes a sudden increase in the pump load. This has caused problems such as engine rotation becoming unstable and engine stalling.

In addition, at the same time as the piston stops sliding, all the fluid consumed by the power cylinder is returned to the tank via the relief valve, so a large amount of flow passes through the relief valve, causing abnormal noise and heat generation. There was a problem that it caused the oil temperature to rise.

<Structure of the Invention> The present invention has been made to solve such conventional problems, and is provided with a control device that controls power assist of a power cylinder based on manual steering torque, and this control device includes A pressurized conductor that is installed at the end of the gear housing of the steering device or the power cylinder that is integrated with the gear housing and that contacts the piston that slides in the power cylinder or a part that moves together with the piston to output an electric signal. The structural feature is that a pressure-sensitive sensor made of rubber is connected.

Function> Since the device of the present invention has the above configuration, when the steering handle is steered to the steering end and the piston reaches the stroke end, the ball joint integral with the piston comes into contact with the pressure sensor.

When the pressure-sensitive sunner is pressurized to this ball joint, current is conducted and a signal is output to the control circuit.

The control circuit applies current to the solenoid of the solenoid control valve, causing the spool to slide. As a result, the electromagnetic control valve is opened and the passage leading to both end chambers of the power cylinder is bypassed. This eliminates a sudden increase in pump pressure and prevents an increase in pump load. Furthermore, the flow rate of fluid passing through the relief valve is also reduced, making it possible to prevent abnormal noise and heat generation.

<Example> Embodiments of the present invention will be described below based on the drawings.

In FIG. 1, reference numeral 10 includes a rack and pinion type power steering device, a gear housing 11, a servo valve 12, and a power cylinder 13.

A steering rod 14 is slidably passed through the gear housing 11 and the power cylinder 13, and both ends of the steering rod 14 are connected to ball joints 15 and 16.
It is connected to the running wheels via. Further, a piston 17 is formed on the steering rod 14, and this piston 17 is slidably fitted into the power cylinder 13.

Further, a steering handle 20 is connected to the servo valve 12 via a handle shaft 19. By applying manual steering torque to the steering handle 20 and controlling the rotation of the servo valve 12, the pressure fluid from the pump 21 is controlled to be supplied to and discharged from the power cylinder 13, and the increased steering torque by the power cylinder 13 is controlled. The signal is transmitted to the steering wheels.

An electromagnetic control valve 30 is provided between the servo valve 12 and the power cylinder 13. This electromagnetic control valve 30 bypass-controls the passage leading to both end chambers of the power cylinder 13, and as shown in FIG.
and has.

The spool 32 is normally held at the lower end, blocking a passage 34 communicating with the left chamber of the power cylinder 13 and a passage 35 communicating with the right chamber. However, when an attractive force is applied to the spool 32 according to the current value applied to the solenoid 36,
The spool 32 is displaced upward against a spring 37, and the passages 34 and 35 are communicated with each other via a bypass slit 38 formed in the spool 32.

The electromagnetic control valve 30 is connected to a control circuit 40.

This control circuit 40 includes a microprocessor 41 and an RO
The main components are M42 and RAM 43, and a solenoid drive circuit 44 is connected to this microprocessor 41 to control the electromagnetic control valve 30.

Additionally, the microprocessor 41 includes pressure sensitive sensors 50 and 51.
is connected. As shown in Fig. 3, this pressure-sensitive sensor 50, 51 is made of pressurized conductive rubber 5, which is made of silicone rubber mixed with nickel fine particles of micron size, as a switch body.
1, both sides of the processed grooved electric rubber 5 are sandwiched with flat braided wire electrodes 54 made of braided conductive wires, and the outside is further covered with silicone rubber 55, and pressure is applied from the outside to remove the nickel fine particles. When the two approaches, the resistance value changes and current flows.

As shown in FIGS. 4 and 5, such pressure-sensitive sensors 50 and 51 are arranged so as to surround the steering iron 14 in the cylinder end 18 screwed into the end of the gear housing 11 and the end of the power cylinder 3, respectively. The ball joints 15 and 16 are arranged so as to come into contact with the ball joints 15 and 16 as the piston 17 slides. Therefore, when the ball joints 15, 16 come into contact with the pressure sensors 50, 51 and pressure is applied, the pressure sensors 50, 51 become electrically connected, and it is possible to detect that the piston 17 has slid to the stroke end.

Next, the operation of the apparatus of the present invention having the above configuration will be explained.

First, when the engine is started, the engine drives the pump 21, and the pump 21 supplies pressurized fluid to the servo valve 12. Since this servo valve 12 is a normal oven type valve, when the servo valve 12 is in a neutral state, the pressure fluid supplied to the servo valve 12 is returned to the tank as it is, and the pump pressure does not increase.

However, when the steering handle 20 is steered from the above-mentioned neutral state to the steering end, such as stationary steering, the fluid supplied from the pump 21 is returned to the tank via the relief valve of the circuit after the piston 17 reaches the stroke end. Therefore, the pump pressure suddenly rises to the relief pressure, and at the same time, the flow rate of fluid flowing from the relief valve to the tank increases rapidly.

This increase in pump pressure rapidly increases the load on the pump 21, that is, the engine load, making the engine rotation unstable.
Furthermore, an increase in the flow rate passing through the relief valve causes abnormal noise and heat generation.

However, in the present invention, the ball joints 15, 16
comes into contact with the pressure-sensitive sensor 50 or 51, making the pressure-sensitive sensor 50 or 51 conductive.

The control circuit 40 detects conduction between the pressure sensors 50 and 51 and applies current to the electromagnetic control valve 30.

This applied current causes the spool 32 to slide and the passage 3
4 and 35 are communicated via a bypass slit 38. As a result, the pressure fluid to be supplied to the power cylinder 13 is bypassed to the tank, suppressing the increase in pump pressure, and as a result, there is no sudden increase in pump load and engine stall associated with it. The flow rate is also reduced, and noise and heat generation in the relief valve are also prevented.

In the above embodiment, a rank and pinion type power steering device is described in which pressure sensors 50 and 51 are attached to the end of the gear housing 11 and the cylinder end 18, but the present invention is not limited to this. (As shown in FIG. 5, in the pole screw type steering device, pressure sensors 60 and 61 are provided inside the power cylinder 62,
The pressure sensors 60 and 61 may be directly pressed by the piston 63.

Further, in the above embodiment, the passage 34 passing the electromagnetic control valve 30 to both end chambers of the power cylinder. ' 35 is provided to bypass, but it is not limited to this.
A drain passage is connected to the supply passage from the pump 21 to the servo valve 12, and an electromagnetic control valve 30 is installed in this drain passage.
may be inserted.

<Effects of the Invention> As described above, the present invention is provided with a control device that controls the power assist of the power cylinder based on manual steering torque, and this control device includes a gear housing of the power steering device or a gear housing thereof. A pressure-sensitive sensor made of pressurized conductive rubber that outputs an electric signal when it comes into contact with a piston that slides inside the power cylinder or a part that moves together with the piston is connected to the end of the integrated power cylinder. Because of this configuration, the pressure sensor is pressed at the same time as the piston of the power cylinder slides to the stroke end, and the signal from this pressure sensor can detect the steering end and control the opening of the electromagnetic control valve. This prevents a sudden increase in pump load and the accompanying engine stall, and also reduces the flow rate of the pressure fluid returned from the relief valve to the tank (which reduces noise and heat generation at the relief valve). It has the advantage of being preventive.

Furthermore, the present invention has a configuration in which the pressure sensor is brought into contact with the piston of the power cylinder or a part that is integral with the dirt to detect the steering end, so there is no restriction on installation space. The pressure sensor is made of pressurized conductive rubber, and has the advantage of reducing impact at the end of the stroke of the piston.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention; FIG. 1 is a diagram showing the power steering device of the present invention, a hydraulic circuit and a control circuit for controlling the power steering device, FIG. 2 is a sectional view of an electromagnetic control valve, and FIG. Figure 4 is a cross-sectional view showing the pressure sensor, Figure 4 is a partial cross-sectional view of the end of the gear housing, Figure 5 is a partial cross-sectional view of the end of the power cylinder, and Figure 6 is a partial cross-sectional view of the end of the power cylinder. FIG. 3 is a sectional view of a power steering device showing another embodiment of the present invention. 12... Servo valve, 14... Steering blonde, 17... Piston, 20... Steering handle, 2
DESCRIPTION OF SYMBOLS 1... Pump, 30... Solenoid control valve, 40... Control circuit, 50.51... Pressure-sensitive sensor.

Claims (1)

[Claims] (1) In a power steering device that controls the supply and discharge of pressure fluid from a pump to a power cylinder by rotating a servo valve based on a manual steering torque applied to a steering handle, the power is generated based on the manual steering torque. A control device for controlling power assist of the cylinder is provided, and the control device includes a gear housing of the power steering device or
A pressure-sensitive sensor made of pressurized conductive rubber is installed at the end of the power cylinder, which is integrated with this, and outputs an electric signal when it comes into contact with a piston that slides inside the power cylinder or a part that moves together with the piston. A control device for a power steering device, characterized in that: