JPS587503B2 - Power steering steering force control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a steering force control device for power steering.

General power steering was used primarily to reduce the steering force, so the driver could feel changes in the steering force, the steering became unstable when driving at high speeds or on mountain roads, and the driver could feel the steering force change when driving at high speeds or on mountain roads. There were times when the steering wheel was turned too far or turned back too far, which could be dangerous.

The present invention aims to solve the above-mentioned disadvantages. - Controls the steering force so that it is as light as possible when the steering wheel is turned off, and the weight is proportional to the vehicle speed and turning condition when driving. This invention attempts to provide a steering force control device.

On the other hand, when the vehicle is turning, it is ideal to increase or decrease the steering force of the steering wheel depending on the degree of the vehicle's turning, that is, the yawing motion of the vehicle that comes from visual perception, or the centrifugal force that comes from the inertia of the vehicle's body weight.

In view of the above points, the present invention changes the steering force so as to increase in response to an increase in the lateral acceleration generated in the vehicle due to steering, and has the following features.

(1) Since the steering force increases as the centripetal acceleration or lateral acceleration increases, the turning state can be felt by the steering force, and furthermore, since the steering force and centripetal acceleration change correspondingly, the driver can feel the turning state. This allows for stable handling without becoming unbalanced.

(2) Since the centripetal acceleration and the side force that the tire receives are interrelated, the tire's limit performance can be felt through the steering force.

Therefore, it is possible to prevent accidents such as spinning of the vehicle due to excessive steering or excessive steering caused by being unaccustomed to high-speed driving.

(3) When the vehicle is stopped, the centripetal acceleration becomes zero, so if this point is set as a singular point, the stationary steering force can be made very light.
The advantages of original power steering can be fully utilized.

(4) As for vehicles equipped with power steering, the oil pressure or oil flow rate of the power steering is controlled by centripetal acceleration, so it can be adopted in most vehicles.

Embodiments of the present invention will be described below with reference to the drawings.

Reference numeral 1 in FIGS. 1, 6, and 7 indicates a conventional torsion bar integrated type power steering system, which is supplied with a constant flow rate of working fluid by a constant flow pump 2 activated by the engine.

・When steering the steering wheel 3, the torsion bar 4 is twisted,
A torsion torque corresponding to the torsion angle is applied to the driver as a reaction force, and at the same time, pump oil pressure PP corresponding to the torsion angle of the torsion bar 4 is applied to the side chamber 6a or 6b of the piston 5 depending on the steering direction of the handle 3. Conveyed.

This hydraulic pressure PP causes the piston 5 to generate a force in a direction that aids steering, thereby rotating the sector wheel 7.

The above is the same as conventionally known power steering, but
In this invention, as shown in FIG. 1, it is possible to take out the hydraulic pressure from the power steering inlet port 8.

The oil pressure in the inlet port 8 is guided to a proportional electromagnetic flow control valve 9 (hereinafter simply referred to as a control valve), and the throttle valve 1
1 is opened and drained.

Note that reference numeral 12 denotes a lateral acceleration sensor that detects a lateral acceleration value generated in the vehicle, and the signal from this lateral acceleration sensor 12 is amplified by an amplifier 13 to cause a control current {circle around (2)} to flow through the DC solenoid 10.

Therefore, the oil pressure at the inlet port 8 will be reduced in response to the lateral acceleration occurring in the vehicle.

The detailed structure of the lateral acceleration sensor 12 is as shown in FIG. 2, for example, as shown in FIG.
21, and a weight 124 supported by leaf springs 122, 123 is provided in this space, and strain gauges R1, R2 are installed on both sides of each leaf spring 122, 123.
and R3 and R4 are arranged and provided.

By arranging the sensor 12 so that the weight 124 swings in the left-right direction of the vehicle, the resistance generated in the strain gauges Rl=R2=R3 and R4 increases or decreases when lateral acceleration acts on the vehicle.

FIG. 3 shows an electric circuit including strain gauges R, , R2, R3, and R4 provided in the lateral acceleration sensor 12 of FIG. Rectifier 12
6, the signal is rectified and converted into a DC signal.

FIG. 4 shows the configuration of an example of the control valve 9, in which the port 111 is connected to the drain port 1 through the variable orifice 112.
13, and the drain port 113 communicates with an oil reservoir.

The variable orifice 112 is formed by a slit 101 and a groove 110 provided in the spool 114, and is variable depending on the degree of alignment between the two.

The spool 114 is pressed to the right in the figure by a spring 115, and this pushing force is set by an adjustment screw 116.

Note that 116a is a fixing nut for the screw 116.

The orifice 11 is configured as described above.

The DC nolenoid 10 has a force F proportional to the current flowing through it.
The position of the spool 114 is adjusted by the balance between the force F proportional to the current and the spring 115, and once the position of the spool 114 is determined, the corresponding opening degree of the variable orifice 112 is determined. .

The hole 117 installed in the spool 114
It is a useless thing that gives damping to.

In general power steering, the characteristics are fixed as shown in b in Fig. 11, regardless of whether the vehicle is stationary or at high speed. Steering force can be reduced, reducing the burden on the driver.

This is because when the vehicle speed is zero, no lateral acceleration occurs, so no control current flows and the opening degree of the variable orifice 112 becomes zero.

That is, at this time, the hydraulic oil does not flow into the variable orifice 112,
The function matches that of conventional power steering.

As the vehicle speed increases, the lateral acceleration caused by steering increases accordingly, so the control current increases in accordance with the lateral acceleration, the spool 114 moves to the left in FIG. 4, and the opening degree of the variable orifice 112 increases. The hydraulic pressure of the power steering 1 caused by the steering increases and decreases because hydraulic oil escapes from the variable orifice 112.

This means that the larger the opening degree of the variable orifice 112 is, the easier the hydraulic oil will flow, so the oil pressure of the power steering 1 will not increase.

Therefore, the output torque relative to the steering torque becomes smaller.

However, as the vehicle speed and turning angle increase, as shown in FIG. 11, the steering torque can continuously change from a characteristic such as PA to C.

When using the lateral acceleration sensor shown in FIG. 2, when the vehicle is tilted laterally, the tilt component is also applied to the steering force as a control signal, resulting in a lack of accuracy in steering force control.

Therefore, in the present invention, it is preferable to use a late gyro shown in FIG. 5 instead.

In this late gyro, the centripetal acceleration is proportional to the square of the yaw angular velocity using the turning radius as a variable, as shown in equation (1) below.

Furthermore, as shown in equation (2) below, the vehicle speed and yaw angular velocity are R
is changed as a variable.

From these, if the yaw angular velocity is sensed, both the centripetal acceleration and the vehicle speed are sensed, which compensates for the major drawback of the power steering 02, which is a win-win situation.

With this device, the longitudinal and lateral inclinations of the vehicle do not affect the detection of lateral acceleration.

Ac=Rω2...(1) ω=■/R...(2) However, Ac: Centripetal acceleration R: Turning radius ω: Yaw angular velocity ■: Vehicle speed The late gyro is shown in Figure 5. Top 21 that rotates like this
, a frame that supports the rotation axis of this top, that is, a gimbal 22, and a spring 2 that connects this gimbal and the base 23.
4 as the main components.

The yaw angular velocity is detected by the amount of deflection of the spring 24.

Since the rotating top 21 of the gyro is given angular momentum, in order to change the axis of rotation, it is necessary to apply an external force corresponding to the rate of change.

That is, when the base 23 is attached to the vehicle,
When the vehicle attempts to change direction and generates a yaw angular velocity, the rotational axis of the top 210 attempts to maintain that state, so the spring 24 flexes and exerts the force necessary to change the rotational axis.

This amount of deflection is converted into an electrical signal by a potentiometer 25 and taken out.

This amount of deflection can also be extracted mechanically.

When converting into an electrical signal, the lateral acceleration sensor 12 shown in FIG. 1 is replaced with the above-mentioned late gyro.

FIG. 6 shows another example of the present invention. In this example, a throttle 3 is provided in front of the inlet port 8 and is operated by a solenoid 31 to reduce its opening in response to a signal from a lateral acceleration sensor 12.
A control valve 30 having 2 is arranged.

The inlet oil pressure is reduced in accordance with the throttle of the control valve 30, and the same effects as in the embodiment described above can be achieved.

In addition, 33 is an IJ single flap valve.

Still in this example, there is a reaction force chamber 3 in the power steering device 1.
4, the hydraulic pressure P downstream of the control valve 30
By supplying P to the reaction force chamber 34 as shown by the dotted line in FIG. 6, the steering force felt by the driver can be adjusted more appropriately by the hydraulic pressure P, which increases in accordance with the lateral acceleration.

FIG. 7 shows still another embodiment of the present invention, in which the side chambers 6a, 6b of the piston 5 are commonly connected to the reservoir via check valves 41', 42', and the check valves 41' , 42', a control valve 40 having a throttle 42 operated by a solenoid 41 to increase its opening in response to a signal from the lateral acceleration sensor 12 is disposed.

The steering hydraulic pressure that presses the piston 5 is the throttle 42 of the control valve 40.
It is designed to decrease according to the above-described embodiment, and the same effects as those of the above-mentioned embodiment can be achieved.

FIG. 8 shows still another embodiment of the present invention. In this embodiment, a lateral acceleration sensor 12 is connected between the side chambers 6a and 6b of the piston 5.
The control valve 50 is driven by a solenoid 51 in response to a signal from zero and has a throttle 52 whose opening degree gradually increases from zero. Make it.

In each of the above embodiments, the steering force is controlled using a continuously changing aperture, but the steering force may be controlled in stages as described below.

That is, in the case of the embodiment shown in Fig. 1.7.8 where the opening degree increases according to the lateral acceleration, a switching valve as shown in Fig. 9 may be used, and the embodiment shown in Fig. 6 may be used. In the case where the opening degree decreases depending on the lateral acceleration, such as the one shown in FIG. 10, the Yongei switching valve shown in FIG. 10 may be used.

When the solenoid 610 is turned on, the switching valve in FIG. 9 is set to the 62-valve arrangement, when the solenoid 61 is turned off, the spring 63 causes the switching valve to be set to the 64-valve arrangement, and when the switching valve n solenoid 71 in FIG. It is assumed that when the nolenoid 71 is turned off, the spring 73 sets the valve to the valve position 74.

It goes without saying that instead of a switching valve that changes in two stages as described above, a switching valve that changes in multiple stages by using a plurality of solenoids may be used.

[Brief explanation of drawings]

Fig. 1 is a schematic system diagram of the device of the present invention, Fig. 2 is a sectional view of a lateral acceleration sensor used in the device of the invention, Fig. 3 is a circuit diagram for extracting a control current from the lateral acceleration sensor, and Fig. 4 is a diagram of the present invention. FIG. 5 is a cross-sectional view of a control valve used in the inventive device, FIG. 5 is a perspective view of a late gyro used in place of the lateral acceleration sensor shown in FIG. 2, and FIGS. 6 to 8 show three other examples of the present invention. A schematic system diagram, FIGS. 9 and 10 are explanatory diagrams of a switching valve that can be used in place of the control valve of the apparatus of the present invention, and FIG. 11 is a diagram of the operating characteristics of the apparatus of the present invention. 1...power steering, 2...pump, 3...
・Steering handle, 4... Torsion bar, 5
．． ．． ．． Power Pis 1・n, 6at6b...side chamber, 7・
...Sector gear, 8...Hydraulic inlet port}, 9,30
, 40...; control valve, 10, 31, 41, 51...
Solenoid, 11, 32, 42, 52... variable aperture,
13... Amplifier, 21... Top, 22... Gimbal, 23... Base, 24... Spring, 25...
... Potentiometer, 101 ... Slit, 110
...Groove, 111...Hydraulic pressure/inlet port, 112...
... Orifice, 113 ... Drain port, 114.
...Spool, 115...Spring, 116...Adjustment screw, 117...Dunbar hole, 120...Case, 1
21... Brake oil chamber, 122, 123... Leaf spring, 1
24... Weight, R1, R2, R3, R4... Strain gauge, 125... Bridge, 126... Rectifier.

Claims (1)

[Scope of Claims] 1. A power steering system in which hydraulic pressure supplied from a pump is selectively supplied to and discharged from a power cylinder by a control valve operated by a steering wheel, and the steered wheels are steered in response to the steering wheel. A drain passage having a control valve is connected to the oil supply passage to the control valve, and the throttle opening of this control valve is configured to increase according to the lateral acceleration generated in the vehicle, thereby controlling the steering force according to the driving state. A steering force control device for power steering, characterized in that it is configured to. 2. In power steering, in which hydraulic pressure supplied from a pump is selectively supplied to and discharged from a power cylinder by a control valve operated by a steering wheel, and the steered wheels are steered in response to the steering wheel, oil is supplied to the control valve. A steering force control device for power steering, characterized in that a control valve is provided in a passage, and the throttle opening of the control valve is reduced in accordance with lateral acceleration generated in a vehicle. 3 In power steering, in which hydraulic pressure supplied from a pump is selectively supplied to and discharged from a power cylinder by a control valve operated by a steering wheel, and the steered wheels are steered in response to the steering wheel, the hydraulic pressure generated in the power cylinder is controlled. 1. A steering force control device for power steering, characterized in that the control is performed by a control valve whose throttle opening increases in accordance with an increase in lateral acceleration occurring in a vehicle.