JPH0419065B2 - - Google Patents

Description

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

(Prior Art) Conventionally known devices of this type control 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.

(Problems to be Solved by the Invention) In the conventional device as described above, it was adapted to the driving conditions by simply controlling the flow rate control valve, so there was a problem that it could not cope with all 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, when stopped or at extremely low speeds,
There was a problem that made it impossible to increase the power assist.

An object of the present invention is to provide a power steering device that can be adapted to various driving conditions.

(Means for Solving the Problems) 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 a power cylinder. The present invention is based on a power steering device equipped with a solenoid valve for guiding pressure to a reaction force chamber of the control valve.

Based on the above device, the present invention connects an output device to each of the prime mover and the flow control valve, which operates according to a signal detected by a detector, and connects the output device to the prime mover when stopped or at extremely low speed. The configuration is such that the rotational speed of the prime mover is slightly increased by the action of the detector, and the flow characteristics of the flow rate control valve are adjusted by the operation of the output device according to the running conditions, and the detector and solenoid valve are connected. ,
The solenoid valve is controlled by the output signal from the detector, the reaction force chamber of the control valve is connected to the tank or pump, and the opening degree at the time of communication is controlled. The feature is that the power steering mode is switched from the power steering mode to the manual steering mode.

(Function) Since the present invention is configured as described above, it is possible to control the rotational speed of the prime mover, the flow rate characteristics of the flow control valve, the pressure of the reaction force chamber of the control valve, etc., and to adapt to all running conditions. become.

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

Output devices 1 and 2 are connected to each of the prime mover m and the flow rate control valve F, and these output devices 1 and 2 are connected to a detector D.

This detector D is connected to the steering shaft S and detects the steering angle or angular velocity of the steering wheel H, as well as the steering torque and the like as electrical signals. Furthermore, this detector D is also connected to the engine E to detect the vehicle speed as an electrical signal.

The detector D thus configured detects each of the above-mentioned signals, operates a predetermined output device according to these signals, and controls the pump P or flow control valve F corresponding to the output devices 1 and 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 of the detector D. This proportional solenoid is connected to the throttle valve of the prime mover m, and adjusts the opening degree of the throttle valve.
The number of revolutions is controlled.

It should be noted that the configuration of the output device 1 with a proportional solenoid is merely an example, and in short, any device that controls the rotational speed of the prime mover m in accordance with the output signal of the detector D may be used. Also, this prime mover m
When an electric motor is used as the output device 1, a variable resistor or the like may be used as the output device 1, for example.

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

Then, an output device 2 connected to this flow control valve F
The controller adjusts the flow rate characteristics of the flow control valve F in accordance with the output signal from the detector D, and determines the flow rate supplied from the pump P to the power cylinder.

Furthermore, the control valve C has a pump port 4 and a tank port 5 formed in its main body 3, and also has a spool 6 slidably installed therein. Then, both ends of this spool 6 are connected to reaction force chambers 7,
8, and springs 9, 10 are loaded into the reaction force chambers 7, 8.

The reaction force chambers 7 and 8 thus constructed are connected to the port 11 of the solenoid valve V. In addition, this solenoid valve V usually maintains the closed position shown in the figure and blocks communication between the port 12 that communicates with the pump P and the port 11 that communicates with the reaction force chambers 7 and 8. Connect to T. Then, when the solenoid is energized, both ports 1
1 and 12 communicate with each other and guide the pressure from the pump P to the reaction force chambers 7 and 8.

The solenoid valve V configured as described above is connected to the above-mentioned detector D, and opens and closes in response to a vehicle speed signal detected by the detector D. 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.

Further, the main body 3 supports a pinion shaft 13, which rotates integrally 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 along the rack a predetermined distance in the direction of arrow 15. Furthermore, a drive lever 16 is provided around the pinion shaft 13 so that the drive lever 16 swings about a fulcrum 17 when the pinion shaft 13 moves in the direction of the arrow 15.

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

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, but the reaction force chambers 7 and 8 are When pressure is introduced, 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 port 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 perform power assist.

Thus, 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, that is, the connecting pin 18 tends to swing. At this time, if the solenoid valve V is held in the closed position as described above and the reaction force chambers 7 and 8 are in communication with the tank T, the spool 6 will move from the connecting pin 18 as the connecting pin 18 swings. Move in the swing direction.

Along with this movement of the spool 6, the pump P
The fluid from flows into one chamber of the power cylinder, and the other chamber communicates with the tank T.

Therefore, the steering becomes powered assisted.

On the other hand, when the solenoid valve V is held in the open position, pressure from the pump P flows into the reaction chambers 7 and 8. When pressure flows into the reaction force chambers 7 and 8, the spool 6 is pressed from both sides. Therefore, even when the handle H is turned, the spool 6 is not switched and only the pinion shaft 13 is rotated, resulting in a manual steering state.

In such a steering device, the steering force of the handle H and the output of the power cylinder are
Control so that the relationship shown in the figure is achieved.

In other words, as the vehicle speed increases from _V1 to Vn, the output of the power cylinder is decreased and the steering force is increased.

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 extremely low speed, the turning resistance is large, so the steering torque also becomes large. Therefore, the detector D 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 D 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 control valve F is fully open,
Furthermore, as 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.

Point b in FIG. 3 is the conventional discharge amount when stopped or at an extremely low speed. Therefore, it is clear that the discharge amount a in this embodiment is greater than the above-mentioned discharge amount b. I understand.

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 the engine is stopped or at extremely low speed, the rotational speed of the prime mover m is increased, the discharge amount of the pump P itself is increased, and the operating force of the handle H is reduced.
When driving at medium to high speeds, it is necessary to reduce the flow rate supplied to the power cylinder and 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 becomes equal to or higher than the set speed, the flow rate controlled by the flow rate control valve F is controlled according to the vehicle speed, and the vehicle speed is detected by the detector D to energize the solenoid valve V.

When the solenoid valve V is energized, it holds the open position and transfers the pressure from the pump P to the reaction chambers 7, 8.
lead to. When pressure flows into the reaction force chambers 7 and 8, the movement of the spool 6 is restricted, so even if the handle H is turned, the spool 6 does not move. Therefore, the supply of fluid to the power cylinder is blocked, and a state of manual steering is established in which the rack is moved by the rotation of the pinion shaft 13.

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

In addition, as the detector D in the above embodiment,
A microcomputer may also be used. Also,
The detection signal may be of any type as long as it can specify the driving conditions.

(Effects of the present invention) According to the device of the present invention, it is possible to control the rotational speed of the prime mover, the flow rate characteristics of the flow rate control valve, the pressure of the reaction force chamber of the control valve, etc., and to adapt to all running conditions. Become.

Further, since the device of the present invention communicates the reaction force chamber and the pump via a solenoid valve, it has the following advantages over, for example, a structure in which the reaction force chamber is locked.

That is, in the case of a device that completely locks the reaction force chamber, there is a problem that air in the pipe line and the reaction force chamber gets mixed in, which reduces the incompressibility of the oil, resulting in a lack of reliability. On the other hand, in the device of the present invention, the discharge pressure of the pump is applied to the reaction force chamber, so even if air gets mixed in, it will be crushed. Therefore, the device of the present invention has the advantage of being more reliable than the device that locks the reaction chamber as described above.

[Brief explanation of drawings]

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... Prime mover, P... Pump, F... Flow rate control valve, C... Control valve, 1, 2... Output device, D... Detector, 7, 8... Reaction force chamber, V... Solenoid valve.

Claims (1)

[Claims] 1 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 a control valve that applies pressure to the reaction force chamber of this control valve. In a power steering device equipped with a solenoid valve for guiding, an output device that operates according to a signal detected by a detector is connected to each of the prime mover and the flow control valve,
When stopped or at extremely low speed, the output device connected to the prime mover is configured to slightly increase the rotational speed of the prime mover, and the flow characteristics of the flow rate control valve are adjusted by the operation of the output device depending on the running conditions. At the same time, the above-mentioned detector and a solenoid valve are connected, and the solenoid valve is controlled by the output signal from the detector, and the reaction force chamber of the control valve is communicated with the tank or pump, and when the communication is made, the opening of the solenoid valve is controlled. A power steering device that is configured to control the speed and switches from power steering to manual steering when the speed exceeds a set speed.