JPS6022558A - Power steering device - Google Patents

Abstract

PURPOSE:To secure such a power steering device as capable of meeting every running condition upon securing optimum steering power, by detecting a signal which specifies the running condition of a car. CONSTITUTION:A detector D controls a pump P corresponding to each of outputters 1 and 2. The outputter 2 connected to a flow control valve F adjusts a flow characteristic of the flow control valve F according to an output signal out of the detector D and determines a feed flow rate from the pump P to a power cylinder. A solenoid valve V is connected to the detector D and opens or closes itself according to the speed signal or the like detected by this detector D. In time of being below the setting speed, the solenoid valve V keeps a close position but when exceeding the setting speed, it keeps an open position.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power steering device that detects a signal specifying the driving conditions of a vehicle and obtains an optimal steering force.

(Conventional Device) This type of device, which has been known in the past, controls a flow rate control valve using a vehicle speed signal, a steering wheel operation signal, or the like to adjust the flow rate supplied to the power cylinder.

For example, when the speed exceeds a set speed, the flow rate supplied to the power cylinder is reduced to enter a manual steering state, and when the speed is below the set speed, the flow rate supplied to the power cylinder is increased to enter a power steering state.

However, it is not enough to just control the above flow control valve.

It had the disadvantage of not being able to adapt to all types of driving conditions.

For example, when the pump is stopped or at extremely low speed, even if the opening degree of the flow control valve is maximized, if the pump discharge amount is the maximum, a flow rate higher than that cannot be secured. Therefore, there is a problem in that the power assist cannot be further increased when the vehicle is stopped or at extremely low speeds.

(Objective of the Present Invention) An object of the present invention is to provide a power steering device that can be adapted to all driving conditions.

(Embodiment of the present invention) The hydraulic circuit system of this power steering device includes a prime mover m
A pump P connected to the pump P is connected to a flow control valve F, and a control valve C is connected to the flow control valve F.

Note that, although the above-mentioned prime mover m is normally used in common with a car engine, in the illustrated embodiment, the car engine E and the prime mover m are shown separately for convenience. However, it goes without saying that this embodiment can be applied even if the engine E and the prime mover m are completely separate.

An output device 1.2 is connected to each of the prime mover m and the flow rate control valve F.
is connected to the detector.

This detector is connected to the steering shaft S,
The handle angle of the handle H, its angular velocity, and even the handle torque are detected as electrical signals. Furthermore, this detector is also connected to the engine E to detect the vehicle speed as an electrical signal.

Such a detector detects each of the above-mentioned signals, operates a predetermined output device according to those signals, and controls the pump P or flow control valve F corresponding to the output device 1.2. do.

That is, the output device 1 connected to the prime mover m is constituted by a proportional solenoid that operates according to the output signal from the detector. This proportional solenoid is connected to a throttle valve of the prime mover m, and adjusts the opening degree of the throttle valve to control the rotational speed of the prime mover m.

The reason why this output device 1 is composed of a proportional solenoid is as follows.
This is just an example, and in short, any system that controls the rotational speed of the prime mover m in accordance with the output signal of the detector may suffice. Further, when an electric motor is used as the prime mover m, a variable resistor or the like may be used as the output device l, for example.

Further, the output device 2 connected to the flow rate control valve F also uses a proportional solenoid in this embodiment.

The output device 2 connected to this flow control valve F adjusts the flow rate characteristics of the flow control valve F according to the output signal from the detector, and determines the flow rate supplied from the pump P to the power cylinder. ing.

Furthermore, the control valve C has a pump port 4 and a tank boat 5 formed in its main body 3, and also has a spool 6 slidably housed therein. Both ends of this spool 6 face a reaction force chamber 7.8, and a spring 9.10 is loaded in this reaction force chamber 7.8.

The reaction chamber 7.8 thus constructed is connected to the port 11 of the solenoid valve V. Further, this solenoid valve V normally maintains the closed position shown in the figure, and the boat 12 that communicates with the pump P and the port 11 that communicates with the reaction chamber 7.8.
While cutting off the communication with the tank T, the boat 11 is made to communicate with the tank T. When the solenoid is energized, both the boats 11 and 12 communicate with each other, and the pressure from the pump P is transferred to the reaction chamber 7.
．． Leads to 8.

The solenoid valve V thus configured is connected to the above-mentioned detector, and opens and closes in response to a vehicle speed signal etc. detected by the detector. For example, when the speed is below a set speed, the solenoid valve V maintains the closed position, and when the speed exceeds the set speed, the solenoid valve V maintains the open position.

Furthermore, although the main body 3 supports the pinion shaft 13,
This pinion shaft 13 rotates together with the handle H and is engaged with a rack connected to the steering arm 14.

Although the rack is not shown, it is provided in a direction perpendicular to the pinion shaft 13.

The pinion shaft 13 thus constructed is supported so as to be movable in parallel a predetermined distance in the direction of arrow 15 along the rack. Moreover, around this pinion shaft l3,
drive/<-te, and the pinion shaft 13 is aligned with the arrow 1 above.
When moving in five directions, this drive lever 16 moves to the fulcrum 1.
It is designed to oscillate around 7.

A connecting pin 18 is provided on the opposite side of the fulcrum 17 of this drive lever 16, and this connecting pin 18 is connected to the spool 6.
is inserted into.

Therefore, when the pinion shaft 13 moves in the direction of the arrow 15, the drive lever 16 swings, and as the drive lever 16 swings, the spool 6 is switched.
When pressure is introduced into the reaction chamber 7.8, its movement is restricted.

When the spool 6 is in the neutral position shown in the figure, the fluid flowing into the pump port 4 via the flow rate control valve F returns to the tank T via the tank boat 5 as it is. On the other hand, when the spool 6 moves to either the left or right, the fluid is guided to either the left or right chamber of the power cylinder to operate the power cylinder and provide power assist.

When the solenoid valve V is in the closed position and the handle H is turned, the following happens.

That is, when the handle H is turned, the pinion shaft 13 is displaced in the direction of the arrow 15 because the resistance on the rack side is large. Along with this displacement of the pinion shaft 13, the drive lever 16
In other words, the connecting bottle 18 is about to swing. At this time, if the solenoid valve V is held in the closed position as described above and the reaction force chamber 7.8 is in communication with the tank T, the spool 6 will move from the connecting pin 18 as the connecting bottle swings during the day. Move in the swing direction.

As the spool 6 moves, fluid from the pump P flows into one chamber of the power cylinder, and the other chamber communicates with the tank T.

Therefore, the vehicle enters a steering state with power assist I.

On the other hand, if the solenoid valve V is held in the open position,
A pressure hole from the pump P flows into the reaction chamber 7.8I. When pressure flows into the reaction force chambers 7, h, the spool 6 is pressed down from both sides. For that reason, the handle H
Even if the spool 6 is turned, the spool 6 does not switch, and the pinion shaft 13
It becomes a state of manual steering where only the steering wheel rotates.

With such a steering device, /\ndruH
The steering force and the output of the power cylinder are controlled so that they have the relationship shown in FIG.

In other words, as the vehicle speed increases from vl to Vn,
Decrease the output of the power cylinder and increase its steering force.

For example, when the car is stopped or at extremely low speeds, the following control is performed.

In other words, when the steering wheel H is operated when the vehicle is stopped or at an extremely low speed, the turning resistance is large, so that the steering wheel i·lux also becomes large. Therefore, a detector detects the steering wheel torque and also detects the vehicle speed.

When the steering wheel torque and vehicle speed are detected in this way, this detector performs a calculation function and outputs a predetermined signal.

In response to this signal, the solenoid valve V maintains the closed position, the flow rate control valve F is fully opened, and the rotation speed of the prime mover m is slightly increased by the operation of the output device 1, thereby increasing the discharge amount of the pump P. Do more.

In this way, when the flow rate control valve F is fully open and the discharge amount of the pump P increases, the flow rate supplied to the power cylinder increases accordingly, so even if the diversion resistance is large, the handle H can be operated easily. .

Figure 3 shows the correlation between the rotational speed of the prime mover m and the flow rate supplied to the power cylinder.As is clear from this figure, when the prime mover m is stopped or at extremely low speed, The rotational speed of , that is, the supply flow rate to the power cylinder is increased to point a.

The dot in FIG. 3 is the conventional discharge amount when stopped or at an extremely low speed, and it is therefore clear that the discharge amount a in this example is larger than the above-mentioned discharge amount . .

Note that when the prime mover m is shared with the engine E, the rotational speed of the engine E increases under the above conditions, but this increase is sufficient to have almost no effect on the vehicle speed.

In this way, when stopped or at extremely low speeds, the rotational speed of the prime mover m is increased and the discharge amount of the pump P itself is increased to reduce the operating force of the handle H, but when driving at medium to high speeds, the force applied to the power cylinder is increased. Control to reduce the supply flow rate,
It is necessary to increase the steering force.

FIG. 4 shows such a control relationship. In FIG. 4, as the vehicle speed increases, the flow rate control valve F is controlled to reduce the flow rate supplied to the power cylinder.

When the vehicle speed exceeds the set speed, the gas flow control valve F
The controlled flow rate of is controlled according to the vehicle speed, and
The vehicle speed is detected by a detector and the solenoid valve V is energized.

When the solenoid valve ■ is energized, it holds the open position and directs the pressure from the pump P into the reaction chamber 7.8. When pressure flows into the reaction chamber 7.8, the spool 6 does not move even if it is turned. Therefore, the supply of fluid to the power cylinder is blocked, and a state of manual steering is established in which the rack moves by rotation of the pinion shaft 13.

As mentioned above, in this embodiment, vehicle speed, steering wheel torque,
Since the steering wheel angle or the angular velocity of the steering wheel is detected to control the pump P, flow rate control valve F, or control valve C, it is possible to adapt to any driving condition by controlling these organically. .

Note that a microcomputer may be used as the detector in the above embodiment. Further, the detection signal may be of any type as long as it can specify the driving conditions.

(Configuration of the present invention) The configuration of the present invention includes a pump connected to a prime mover, a flow control valve connected to the pump, and a control valve connected to the flow control valve and controlling the direction of flow into the power cylinder. In a power steering device equipped with a solenoid valve for guiding pressure to a reaction force chamber of the control valve, an output device that operates according to a signal detected by a detector is connected to each of the above-mentioned prime mover and flow control valve. However, when the engine is stopped or at very low speed, the rotation speed of the engine is slightly increased by the action of the output device connected to the engine, and the flow rate characteristics of the flow rate control valve are controlled by the operation of the output device according to the running conditions. Along with adjusting
The above detector and solenoid valve are connected, and the solenoid valve is controlled by the output signal from the detector, and the pressure in the reaction force chamber of the control valve is adjusted. When the speed exceeds the set speed, the power steering status is determined. The feature is that the steering mode can be switched from to manual steering.

(Effects of the present invention) Therefore, according to the present invention, the rotational speed of the prime mover and the flow rate control valve can be improved! By controlling the volume characteristics and the pressure in the reaction force chamber of the control valve, it is possible to perform control that adapts to all driving conditions.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention. Fig. 1 is a circuit diagram, Fig. 2 is a graph showing the correlation between steering torque and the power cylinder, and Fig. 3 is a graph showing the correlation between the rotational speed of the prime mover and the power cylinder. A graph showing the correlation between the supply flow rate and FIG. 4 is a graph showing the correlation between the supply flow rate to the power cylinder and the vehicle speed. M...Motor, Pψ...Pump, F-...Flow control valve, C...Control valve, 1.2◆-Medium output device, D...O detector, 7.8...Reverse Force chamber, V--・Solenoid valve. Representative Patent Attorney Nobuyuki Shima Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] A pump connected to the prime mover, a flow control valve connected to this pump, a control valve connected to this flow control valve and controlling the direction of flow into the power cylinder, and leading pressure to the reaction chamber of this control valve. In a power steering device equipped with a solenoid valve, an output device that operates according to a signal detected by a detector is connected to each of the above-mentioned prime mover and flow control valve, and is connected to the above-mentioned prime mover when stopped or at extremely low speed. The rotation speed of this prime mover is slightly increased by the action of the output device, and the flow characteristics of the flow rate control valve are adjusted according to the running conditions by the operation of the two-part output device. The solenoid valve is controlled by the output signal from the detector, and the pressure in the reaction force chamber of the control valve is adjusted. When the speed exceeds the set speed, the power steering state changes to the manual steering state. Switchable power steering device.