JPH0262428B2 - - Google Patents

Description

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

(Prior Art) In a power steering device, for example, as described in Japanese Patent Publication No. 52-39529,
A so-called vehicle speed sensitive type is generally known, which reduces the amount of pressure oil supplied to the power cylinder and reduces the power assist force in response to an increase in vehicle speed. However, in such a vehicle speed sensitive type, the amount of pressure oil supplied decreases as the vehicle speed increases, so when the steering speed is increased, the supply of pressure oil to the power cylinder is delayed, resulting in higher steering resistance. There is a problem where the steering becomes difficult to turn.

On the other hand, in Japanese Patent Application Laid-open No. 57-66071,
Input each signal from the vehicle speed sensor, steering speed sensor, and vehicle lateral acceleration sensor to the control circuit,
It is described that the control circuit controls the amount of pressure oil supplied to the power cylinder by combining it into one control signal and transmitting the signal to a flow rate control valve. In this case, since the steering speed is involved in controlling the amount of pressure oil supplied, a large amount of pressure oil can be supplied to the power cylinder when the steering wheel is turned, but the control circuit has to wait until the steering speed signal is transmitted to the flow control valve. Because there is an element that causes a delay in signal transmission, such as synthesis with the vehicle speed signal, the responsiveness of increasing or decreasing the amount of pressure oil supply to changes in steering speed becomes poor, and when the steering wheel is suddenly turned, the pressure oil supply decreases. There is a problem that the supply cannot keep up, which adversely affects drivability.

That is, the signal from the vehicle speed sensor is usually a pulse signal, and this pulse signal is converted into voltage by a transistor, so it cannot necessarily be said that the responsiveness is high. Therefore, as described above, the method of calculating and combining the signals from the vehicle speed sensor and the signal from the steering speed sensor to obtain one control signal causes a relatively large delay in signal transmission, that is, a delay in response. become. In controlling the amount of pressure oil supplied according to the vehicle speed, the above response delay is not a problem because the vehicle speed itself does not change rapidly when the vehicle accelerates or decelerates, but the Therefore, very fast response is required, and such a request cannot be met.

(Object of the Invention) In view of the above, the present invention provides a pressure oil supply path that connects an oil pump and a power cylinder, and includes a first flow rate control means that is sensitive to a signal from a running state sensor, and a first flow rate control means that is sensitive to a signal from a steering sensor. By interposing the second flow rate control means in parallel and operating the second flow rate control means directly by the steering speed signal, the responsiveness of increase/decrease in the amount of pressure oil supplied to fluctuations in the steering speed is increased.
The purpose is to improve drivability.

(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 via a pressure oil supply path; a running state sensor that detects the running state of the vehicle; and a steering wheel. a steering sensor that detects the steering speed of the power cylinder; a first flow rate control means that controls the amount of pressure oil supplied to the power cylinder; a second flow rate control means that controls the amount of pressure oil supplied to the power cylinder; The two flow rate control means are interposed in parallel to the pressure oil supply path, and the first flow rate control means and the running state sensor are linked,
The second flow rate control means and the steering sensor are linked, that is, the running state sensor and the steering sensor are each independently linked to the first flow rate control means and the second flow rate control means, and the vehicle The first flow rate control means decreases the pressure oil supply amount in response to a transition to a high-speed running state, and the second flow control means increases the pressure oil supply amount in response to an increase in steering speed. , the steering sensor and the second flow rate control means have a one-to-one correspondence.

(Example) In the power steering device 1 shown in FIG. 1, 2 is a steering wheel, 3 is left and right wheels that constitute the front wheels of an automobile, and 4 is a steering wheel that changes the wheels 3, 3 in the left-right direction in accordance with the rotational steering of the steering wheel 2. This is the steering linkage that directs the vehicle.

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 of the wheel are connected via tie rods 11 to a knuckle arm 12 that supports the wheel 3.

A power cylinder 13 for correcting the steering force of the steering wheel 2 is attached to the rack shaft 9. The power cylinder 13 is divided into a first chamber 15 and a second chamber 16 by a piston 14 fixed to the rack shaft 9. 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
The steering wheel 2 is connected to the oil pump 21 driven by the steering wheel 2 through a pressure oil supply path 22.
Pressure oil is selectively supplied to the first chamber 15 and second chamber 16 of the power cylinder 13 in response to the rotation of the power cylinder 13 . Also, gear control valve 1
A return passage 23 extends from 7.

The pressure oil supply path 22 includes a first flow rate control means 24 that controls the amount of pressure oil supplied from the oil pump 21 to the power cylinder 13, a second flow rate control means 25 that also controls the amount of pressure oil supplied, and an adjustment device. Valves 26 are interposed in parallel with each other. The first flow rate control means 24 is a solenoid valve, and as the amount of current applied to the coil 27 increases, the spool 28 moves toward the coil 27 side, and the amount of pressure oil supplied decreases. 1st
A running state sensor 29 that detects the vehicle running state (vehicle speed) is linked to the flow rate control means 24 via a controller 30, and the amount of current applied to the coil 27 increases as the vehicle speed increases. . In this case, the controller 30
The amount of current applied to the coil 27 is changed based on a pulse signal related to the vehicle speed output from the coil 27.

The second flow rate control means 25 is also a solenoid valve, and as the amount of current to the coil 31 increases, the spool 32 moves toward the coil 31 side, and the amount of pressure oil supplied is opposite to the first flow rate control means 24. increases. A steering sensor 33 that detects the steering speed of the steering wheel 2 attached to the lower shaft 7 is linked to the second flow rate control means 25, and as the steering speed increases, the amount of current applied to the coil 31 increases. It's becoming like that. In this case, the steering sensor 33 is of a coil type that changes an output voltage according to the rotational speed of the lower shaft 7, that is, the steering speed, and the amount of current applied to the coil 31 is changed according to this output voltage.

The pressure regulating valve 26 is connected to both the flow rate control valves 24 and 25.
A portion of the pressure oil is drained according to the pressure difference between the upstream side and the downstream side. In addition, in FIG. 1, 35 is a battery, and 36 is an oil tank.

In the power steering device 1, when the vehicle speed increases, the coil 2 of the first flow rate control means 24
7 increases, the amount of pressure oil supplied to the power cylinder 13 controlled by the first flow rate control means 24 decreases, and the power assist force decreases. on the other hand,
When the steering speed increases, the amount of current applied to the coil 31 of the second flow rate control means 25 increases, the amount of pressure oil supplied to the power cylinder 13 controlled by the second flow rate control means 25 increases, and the power assist force increases. growing.

Here, looking at the relationship between the vehicle speed V and the pressure oil supply amount Q, as shown in FIG. ₂ , when the steering speed θ is small, the pressure oil supply amount Q is However, the decrease starts when the vehicle speed V is low, and when the amount of current applied to the coil 27 reaches the maximum, the pressure oil supply amount Q is saturated at the lower limit. As the steering speed θ increases, the output voltage E at the steering sensor 33 increases linearly as shown in FIG. It will be supplied to the power cylinder 13. Therefore, as the steering speed θ increases, the pressure oil supplied via the second flow control means 25 is added to the pressure oil supplied via the first flow control means 24, and the third
As shown by the solid lines θ〓 ₂ and θ〓 ₃ in the figure, the pressure oil supply characteristics change in the direction of increasing the pressure oil supply amount.

Since the steering sensor 33 and the second flow rate control means 25 are directly linked in a one-to-one relationship, the steering sensor 33 increases as the steering speed θ increases.
A change in the output signal is immediately transmitted to the second flow rate control means 25, and even if the steering speed θ is increased, there is no delay in the supply of pressure oil, and the responsiveness of wheel direction change to the operation of the steering wheel 2 is increased.

Note that a manual adjustment means is separately provided to correct the output from the driving state sensor 29 and the output from the steering sensor 33 to a higher or lower side using a variable resistor, etc., and the power steering characteristics can be adjusted according to the driver's preference. You may change it.

Further, when the steering sensor 33 is of an electromagnetic coil type, it is more preferable in terms of responsiveness to configure the electromotive force of the electromagnetic coil to be applied directly to the coil 31 of the second flow rate control means.

Further, as the driving state sensor 29, an engine rotation speed sensor or a transmission gear position sensor may be used instead of the vehicle speed sensor of the above embodiment.

(Effects of the Invention) The present invention provides a second flow rate control means in parallel with a first flow rate control means that is sensitive to vehicle running conditions,
Since the signal from the steering sensor is directly transmitted to the second flow rate control means, there is no need for time required for processing the signal from the running state sensor or for calculating and combining this signal with the steering speed signal. The responsiveness of the increase in the amount of pressure oil supplied to changes in steering speed is reliably increased, a delay in the supply of pressure oil is prevented, and drivability is improved.

[Brief explanation of the drawing]

The drawings illustrate embodiments of the present invention, in which Fig. 1 is an overall configuration diagram of a power steering device, Fig. 2 is a graph showing the relationship between vehicle speed and pressure oil supply amount, and Fig. 3 is a graph showing the relationship between the steering speed and the steering sensor. It is a graph showing the relationship with output voltage. 1... Power steering device, 2... Steering, 13... Power cylinder, 17... Gear control valve, 21... Oil pump, 2
2... Supply path, 24... First flow rate control means, 25
... second flow rate control means, 29 ... running state sensor, 33 ... steering sensor.

Claims (1)

[Claims] 1. A power cylinder that assists the steering force, an oil pump that supplies pressure oil to the power cylinder via a pressure oil supply path, a driving condition sensor that detects the driving condition of the vehicle, and a driving condition sensor that detects the steering speed. and a steering sensor, and the pressure oil supply path includes a first flow rate control means that receives a signal from the driving state sensor and corrects the amount of pressure oil supplied to decrease in response to transition to a high speed driving state; A power steering device characterized in that a second flow rate control means is installed in parallel with a second flow rate control means for receiving a signal from the second flow rate control means and correcting an increase in the amount of pressure oil supplied according to an increase in the steering speed.