JPH0215431B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a power steering device.

(Prior art) Vehicle speed-sensitive power steering devices that reduce the power assist force by reducing the amount of pressure oil supplied to the power cylinder that assists the steering force as the vehicle speed increases are conventional power steering devices for automobiles. Are known.

In this vehicle speed sensitive power steering device, there is a proposal to further correct the amount of pressure oil supplied by the steering speed, as disclosed in Japanese Patent Laid-Open No. 57-66071. That is,
In this proposal, the reference line for the pressure oil supply amount (at zero steering speed) is set at a low level, and the higher the steering speed is, the more the pressure oil supply amount is corrected. Naturally, a response delay occurs until the oil supply amount control valve operates and the pressure oil supply amount actually increases to a predetermined value. In this case, the response delay appears as a lack of pressure oil supply immediately after turning the steering wheel, and as a result,
The driver feels a sense of resistance (feeling like it's stuck) when he or she begins to turn the steering wheel.

(Object of the Invention) The present invention controls the amount of pressure oil supplied to the power cylinder using three signals: a signal related to the running state of the vehicle, a signal related to the steering speed, and a differential signal of this steering speed signal. The pressure oil supply amount is quickly increased at the start of the steering operation, thereby eliminating the feeling of sluggishness due to the delay in response, and enabling a good steering operation.

(Structure of the Invention) The power steering device according to the present invention includes: a power cylinder that assists the steering force; an oil pump that supplies pressure oil to the power cylinder; an oil amount control means that controls the amount of pressure oil supplied; and detects the running state of the vehicle. A steering sensor that detects the steering speed of the steering wheel.A steering sensor that detects the steering speed of the steering wheel.A controller that receives signals from the driving condition sensor and the steering sensor and issues a control signal to the oil amount control means. The above-mentioned controller includes a signal processing means that processes the signal from the driving state sensor so as to reduce the amount of pressure oil supplied in accordance with the transition to high-speed driving, and increases the amount of pressure oil supplied in accordance with the increase in steering speed. a signal processing means for processing the signal of the steering sensor so as to correct the signal; and a signal processing means for differentiating the signal of the steering sensor and processing the signal of the steering sensor so as to correct the increase correction amount of the pressure oil supply amount based on the differentiated signal. The oil quantity control means is configured to issue a control signal to the oil amount control means based on these signal processing means.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

In the power steering device 1 shown in FIG. 1, 2 is a steering wheel, 3 is a left and right wheel that constitutes the front wheels of an automobile, and 4 is a steering linkage that turns the wheels 3, 3 in the left-right direction in accordance with the rotational steering of the steering wheel 2. It is.

In this steering linkage 4, 5 is a steering shaft whose upper end is connected to the steering wheel 2, 6 is an intermediate shaft, and 7 is a lower shaft. A pinion 8 at the lower end of the lower shaft 7 meshes with a rack 10 of a rack shaft 9. Both ends are connected via tie rods 11 to a knuckle arm 12 that supports the wheel 3.

A power cylinder 13 is attached to the rack shaft 9 to assist the steering force of the steering wheel 2. The power cylinder 13 is connected to the rack shaft 9
The chamber is divided into a first chamber 15 and a second chamber 16 by a piston 14 fixed to the chamber. The first chamber 15 and the second chamber 16 communicate with a gear control valve 17 attached to the lower shaft 7 through oil passages 18 and 19.

The gear control valve 17 is connected to the engine 20
A pressure oil supply path 22 communicates with an oil pump 21 driven by
5 and the second chamber 16.
A return passage 23 extends from the gear control valve 17.

The pressure oil supply path 22 is provided with an oil amount control means 24 that controls the amount of pressure oil supplied from the oil pump 21 to the power cylinder 13 . The oil amount control means 24 includes a solenoid valve device 25 and a drain valve device 26. The electromagnetic valve device 25 includes a solenoid 27 and a spool valve 28 whose stroke position is controlled by the solenoid 27, and changes the passage area of the orifice 29 depending on the stroke position of the spool valve 28. That is, as the amount of current applied to the solenoid 27 increases, the spool valve 28 strokes toward the solenoid to throttle the orifice 29 and reduce the amount of pressure oil supplied.
The drain valve device 26 includes a valve body 31 that opens and closes the drain hole 30 and a spring that closes the valve body 31 in the drain hole closing direction. It is designed to drain some of the pressure oil.

A controller 32 that issues a control signal to the solenoid 27 is linked to the flow rate control means 24, and this controller 32 includes a running state sensor 33 that detects the running state (vehicle speed) of the vehicle, and a steering wheel mounted on the lower shaft 7 of the steering linkage 4. A steering sensor 34 and a battery 35 are connected to detect the steering speed of the vehicle. The amount of current applied to the solenoid 27 is controlled by a controller 32 based on signals from a running state sensor 33 and a steering sensor 34.

The specific configuration of the controller 32 is shown in FIG.

In the same figure, 36 is an F/V converter that converts the pulse signal from the running state sensor 33 into voltage;
7 is a differentiation circuit that differentiates the signal from the steering sensor 34; 38 is an addition unit that adds the output voltage from the steering sensor 34 and the output voltage from the differentiation circuit 37; 3;
9 is the output voltage from the F/V converter 36 and the adder 3
This is an amplification section that amplifies the difference between the output voltage from 8 and 8. The output of the amplification section 39 and the output from the triangular wave generation circuit 40 are the (+) of the comparator 41, respectively.
Comparator 4
Output terminal 1 turns on/off energization to solenoid 27.
It is connected to the base of the transistor 42 that controls turning off.

In the above circuit configuration, the voltage according to the vehicle speed V input to the (+) side of the operational amplifier 43 of the amplifier section 39 is E _V , the output voltage of the steering sensor 34 is Eθ〓, and the output voltage of the differentiating circuit 37 is Eθ ¨. Then, the amplifying section 39
The output voltage E of is K( _EV −Eθ〓−Eθ〓). Note that K is a constant.

Therefore, if we look at the relationship between the vehicle speed V and the pressure oil supply amount Q when the steering speed θ = 0, the output voltage of the amplifier 39 is E = KE _V , and at the vehicle speed V = V ₁ (high speed) Assuming that the output voltage is E ₁ and the output voltage at V=V ₂ (low speed) is E ₂ , the relationship between E ₁ , E ₂ and the pulsating voltage E _W of the triangular wave generation circuit 40 is as shown in FIG. 3a. Become.
When the vehicle speed is high, the width _W1 of the pulse signal output from the comparator 41 is wide, as shown in FIG. 3b, and conversely, when the vehicle speed is low, the pulse width _W2 is narrow, as shown in FIG. 3c. . Therefore, the amount of current applied to the solenoid 27 increases as the vehicle shifts to a high-speed running state, the amount of drain from the oil amount control means 24 increases, and the amount Q of pressure oil supplied to the power cylinder 13 decreases. The relationship between the vehicle speed V and the pressure oil supply amount Q is shown by the line θ=0 in FIG.

Next, looking at the relationship between the steering speed θ〓 of the steering wheel 2 and the pressure oil supply amount Q, we can see that the input voltage E of the comparator 41 is
is K( _EV −Eθ〓−Eθ¨), so θ〓=θ〓 ₁
(large), θ〓
If E when = θ〓 ₂ (small) is E ₁₁ and E ₂₂ respectively, then E ₁₁ < E ₂₂ , and this E ₁₁ ; E ₂₂ and the pulsating voltage E _w
The relationship with is shown in FIG. 5a. When the steering speed is high, the comparator 4 is used as shown in Fig. 5b.
The pulse width W ₁₁ from 1 is narrow, and when the steering speed is small, the pulse width W ₂₂ becomes wide as shown in FIG. 5c. Therefore, as the steering speed increases, the amount of current applied to the solenoid 27 decreases, and the drain amount decreases, so the pressure oil supply amount Q increases as shown in FIG.

In other words, the amount of increase in the pressure oil supply amount Q is K(Eθ〓+
θ¨), and the steering speed θ〓=θ〓 ₁ (
Big),
The V-Q characteristics at θ = θ = ₂ (small) are shown in Figure 4.
= θ〓 ₁ , θ〓 = θ〓 ₂ , and θ〓 =
0→θ〓
The increase correction amount q ₁ at =θ〓 ₁ is naturally larger than the increase correction amount q _{2 at θ〓=0→θ〓=θ〓 2 .} As a result, the seventh
As shown in the figure, the steering torque T of the steering wheel 2 remains approximately constant regardless of the magnitude of the steering speed sail.

Therefore, the output characteristics of the steering sensor 34 and the output characteristics of the differentiating circuit 37 are as shown by the solid lines a and b in FIG. The combined signal will be input. Therefore, when using only the steering speed signal, the pressure oil supply amount Q increases with a slight response delay from the rise of the steering speed signal, as shown by the broken line in Figure 8c, but if the differential signal is involved in this, this At the time of rising, a high voltage with a spike waveform is input to the (-) side of the operational amplifier 43, so the output voltage of the operational amplifier 43 becomes low, and in the oil amount control means 24, the amount of current flowing through the solenoid 27 decreases significantly. In other words, the above-mentioned differential signal reduces the energization amount of the solenoid 27 at the rising edge of the steering speed signal, reduces the drain amount, and reduces the pressure oil supply amount Q.
This acts to correct the response delay in increasing the amount of pressure oil supplied, as shown in FIG. 8c.

On the other hand, considering the case where the steering wheel 2 is returned to its original position after being operated, if only the steering speed signal is used,
Even after the steering wheel 2 is operated, the pressure oil supply amount Q continues to increase slightly due to the response delay, so when the steering wheel 2 is returned to its original position, the steering link 2 suddenly becomes lighter (steering torque becomes smaller). On the other hand, the differential signal acts in a direction to reduce the amount of pressure oil supplied immediately after the steering speed signal is interrupted, so that the steering wheel 2 is prevented from suddenly becoming lighter.

In short, the differential signal has the effect of advancing the phase of the increase in the amount of pressure oil supplied, thereby preventing response delays and improving the operability of the steering wheel 2.

In the above embodiment, the signal from the running state sensor 33 and the signal from the steering sensor 34 are combined to control one oil amount control means 24. A first oil amount control means and a second oil amount control means that responds to the signal from the steering sensor 34 are provided in parallel in the pressure oil supply path 22, and each flow rate control means is controlled individually based on the driving state signal and the steering speed signal. It may also be controlled.

Further, it is also possible to amplify the output of the steering sensor 34, differentiate the signal, and provide a separate oil amount control means that responds only to this differentiated signal.

Further, as the driving state sensor, an engine rotation sensor, a transmission gear position sensor, etc. may be used in addition to the vehicle speed sensor.

(Effects of the Invention) According to the present invention, the amount of pressure oil supplied to the power cylinder is controlled by the signal of the driving state sensor, the signal of the steering sensor, and the differential signal of the signal of the steering sensor, so that the steering operation is started. The required amount of oil can be immediately supplied to the power cylinder at times, reducing the feeling of stiffness (feeling of resistance) in steering operation.
You can improve the operability of the steering wheel without having to remember the steering wheel.

[Brief explanation of drawings]

The drawings illustrate embodiments of the present invention; FIG. 1 is an overall configuration diagram of a power steering device, FIG. 2 is a control circuit diagram, and FIG. , Figures 3b and 3c are output characteristic diagrams of the same comparator, Figure 4 is a characteristic diagram showing the relationship between vehicle speed and pressure oil supply amount, and Figures 5a, b, and c are graphs showing the relationship between changes in steering speed. FIG. 6 is a characteristic diagram showing the relationship between steering speed and pressure oil supply amount; FIG. 7 is a characteristic diagram showing the relationship between steering speed and steering torque; Figures 8a, b, and c are characteristic diagrams showing temporal changes in the steering speed signal, differential signal, and pressure oil supply amount, respectively. 1... Power steering device, 2... Steering, 3... Wheels, 13... Power cylinder,
21...Oil pump, 22...Pressure oil supply path, 2
4...oil amount control means, 32...controller, 3
3... Running state sensor, 34... Steering sensor, 3
7... Differential circuit.

Claims (1)

[Claims] 1. A power cylinder that assists the steering force of the steering wheel, an oil pump that supplies pressure oil to the power cylinder, and an oil amount control means that controls the amount of pressure oil supplied from the oil pump to the power cylinder.
Signals from a driving condition sensor that detects the driving condition of the vehicle, a steering sensor that detects the steering speed, and a driving condition sensor are processed according to predetermined signal processing characteristics, and pressure oil is activated in response to the transition to a high-speed driving condition. The supply amount is reduced, and the signal from the steering sensor is processed to increase the pressure oil supply amount according to the increase in steering speed, and the pressure oil supply amount is determined by a differential signal obtained by differentiating the signal from the steering sensor. A power steering device comprising: a controller that issues a control signal to a flow rate control means to correct the increase correction amount.