JPH0615341B2 - Steering force control device for power steering device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a steering force control device for a power steering device including a reaction force mechanism to which a control pressure according to a vehicle speed or the like is supplied.

<Prior Art> As one that controls the steering force of a power squeezing device according to a vehicle speed or the like, there is a device that includes a control device that supplies a control pressure proportional to a vehicle speed or the like to a reaction mechanism. The control device controls the fluid from the pump to a predetermined flow rate by the flow rate control device, controls the control flow rate to a predetermined pressure by the electromagnetic pressure control valve, and supplies the control force to the reaction force mechanism.

<Problems to be Solved by the Invention> In the control device, the spool in the electromagnetic pressure control valve is locked by dust or the like, or dust is clogged in the middle of the flow path leading to the electromagnetic pressure control valve. There is a considerable possibility that the oil flow to the tank will disappear, and as a result, the pressure difference across the flow control valve will disappear and the bypass passage will be closed, and the reaction mechanism will be affected by oil above a certain pressure. There was a problem that the state of manual steering.

<Means for Solving Problems> The present invention has been made to solve the above problems, and includes a supply pump driven by an automobile engine,
A first flow rate control valve that controls the pressure oil discharged from the supply pump to a predetermined flow rate necessary for the power snake device and bypasses the surplus flow, and a bypass flow rate bypassed by the first flow rate control valve to a constant flow rate. A second flow rate control valve that controls the excess flow to the low pressure side and an electromagnetic pressure control valve that controls the constant flow rate of the pressure oil controlled by the second flow rate control valve to a control pressure according to the vehicle speed. The control valve controlled by the electromagnetic pressure control valve is introduced into the reaction mechanism when the control pressure exceeds a predetermined pressure.

<Examples> Examples of the present invention will be described below with reference to the drawings. Reference numeral 10 denotes a gear housing that forms the main body of the power take-up device. A pinion shaft (output shaft) 11 is rotatably supported by the gear housing 10, and the pinion shaft 11 is slidable in a direction intersecting with the pinion shaft 11. It is meshed with the rack shaft 14. Both ends of the rack shaft 14 are connected to steering wheels via a required steering link mechanism, and a piston of a power cylinder (not shown) is operatively connected to the rack shaft 14.

A valve housing 18 is fixed to the gear housing 10, and a rotary servo valve 20 is provided in the valve housing 18.
Is stored. The rotary servo valve 20 is composed of a sleeve valve member 21 and a rotor valve member 22 that are rotatable relative to each other about the axis of the pinion shaft 11, and the rotor valve member 22 is connected to a steering handle. The input shaft) 24 is integrally formed. Manipulating snake shaft 24
Is flexibly connected to the pinion shaft 11 via a torsion bar 25, and is engaged with the pinion shaft 11 so as to be relatively rotatable by a predetermined amount via an engaging portion 24a.

A plurality of port grooves 21a, 22a are formed on the inner circumference of the sleeve valve member 21 and the outer circumference of the rotor valve member 22 at equal angular intervals on the circumference, and the relative rotation between the sleeve valve member 21 and the rotor valve member 22 causes The supply port 26 is connected to one of the supply / discharge ports 28 and 29 connected to both chambers of the power cylinder, and the other is connected to the discharge port 27.

The valve housing 18 is provided at one end of the pinion shaft 11.
A cylindrical portion 30 rotatably fitted therein is formed, and one end of the cylindrical portion 30 is connected to the sleeve valve member 21 via a connecting pin 31. A reaction force cylinder chamber 33 is formed concentrically with the pinion shaft 11 in the cylindrical portion 30, and a flange-shaped reaction force receiving portion 34 formed on the steering shaft 24 is relatively rotatable in the force cylinder chamber 33. Is fitted to.
A ring-shaped reaction force piston 35 is axially slidably fitted in the reaction force cylinder chamber 33 so as to face the reaction force receiving portion 34, and the reaction force piston 35 is fixed by a detent pin 38 to the pinion shaft 11. It has been stopped against. The inner circumference of the reaction force piston 35 is fitted to the steering shaft 24, and the reaction force piston 35 divides the reaction force cylinder chamber 33 into a left chamber and a right chamber. Then, the left chamber is communicated with the introduction port 40 into which the reaction hydraulic pressure is introduced as described later, and the right chamber is communicated with the drain port 41 connected to the reservoir.
A plurality of conical recesses 34a, 35a are circumferentially formed on the opposing surfaces of the reaction force receiving portion 34 and the reaction force piston 35, and a plurality of circumferential engagement balls are engaged with the recesses 34a, 35a. A retainer 37 holding 36 is interposed between the reaction force receiving portion 34 and the reaction force piston 35. Then, the reaction force piston 35 is provided with a web washer 39 provided on its rear surface.
Is always pressed by the engaging ball 36 in a direction in which the engaging ball 36 is engaged.

Reference numeral 50 denotes a supply pump driven by an automobile engine, and a discharge port of the supply pump 50 is connected to the supply port 26 via a first flow rate control valve 51. The first flow rate control valve 51 has a supply passage 45 that connects the discharge port of the supply pump 50 and the supply port 26.
A metering orifice 52 provided therein and a bypass passage 53 which is operated in accordance with the front-rear pressure of the metering orifice 52 so as to keep the front-rear pressure constant.
And a bypass valve 54 that controls the opening of the power supply. The first flow rate control valve 51 supplies the supply port 26 with a constant flow rate required for the power take-up device, and the excess flow is bypassed to the bypass passage 53. First flow control valve 51
The bypass passage 53 is connected to the introduction port 40 of the reaction force cylinder chamber 33 via a second flow control valve 55. The second flow rate control valve 55 is actuated in accordance with the metering orifice 56 provided in the passage 46 connecting the bypass passage 53 and the introduction port 40, and the front-back pressure of the metering orifice 56, and the front-rear direction. A bypass valve 58 that controls the opening of a bypass passage 57 connected to the reservoir so as to always keep the pressure constant, and the second flow rate control valve 55 keeps the flow rate introduced into the introduction port 40 constant. Control and bypass excess flow to the reservoir via bypass passage 57.

An electromagnetic relief valve 60 and a relief valve 80 are connected to the introduction passage 46. A solenoid drive circuit 71 is connected to the solenoid of the electromagnetic relief valve 60, and a computer 70 is connected to the solenoid drive circuit 71. A vehicle speed signal V is applied to the computer 70, and a control current corresponding to the vehicle speed signal V is applied to the solenoid drive circuit 7.
1 to the solenoid of the electromagnetic relief valve 60. As a result, the oil in the introduction passage 46 is controlled to a pressure according to the vehicle speed by the electromagnetic relief valve 60, and this control pressure is transmitted through the introduction port 40 to the reaction force cylinder chamber 33.
Act on. The relief valve 80 has a role of releasing the oil to the reservoir when the pressure of the oil in the introduction passage 46 becomes equal to or higher than a predetermined pressure, and the pressure for releasing the oil is slightly larger than the maximum control pressure by the electromagnetic relief valve 60. Is set. By providing this relief valve 80, the electromagnetic relief valve 60
Are locked or the flow path guided to the electromagnetic relief valve 60 is clogged, and the electromagnetic relief valve 60 is provided in the reaction force cylinder chamber 33.
Oil pressure above the pressure set by does not work.

Next, the operation of the above configuration will be described. The pressure oil discharged from the supply pump 50 is controlled to a predetermined flow rate by the first flow rate control valve 51, and the supply port 2 of the power take-up device is controlled.
6 is supplied. At the same time, the surplus flow from the first flow rate control 51 is controlled to a constant flow rate by the second flow rate control valve 55, and is drained to the reservoir via the electromagnetic relief valve 60. When the vehicle speed is low, a maximum current is supplied to the solenoid of the electromagnetic relief valve 60, and the pressure of the oil in the introduction passage 46 is set to a low pressure by the electromagnetic relief valve 60. Therefore, the reaction force piston 35 is pressed against the engaging ball 36 only by the repulsive force of the web washer 39, and when the steering shaft 24 is rotated by the handle operation, the reaction force piston 3
5 is easily retracted against the repellency of the web washer 39, which allows the sleeve valve member 21 and the rotor valve member 22.
And are rotated relative to each other, and the normal power take-off action is performed.

When the vehicle speed exceeds a predetermined value, the solenoid drive circuit 71 is controlled according to the vehicle speed signal V input to the computer 70, and the current supplied to the solenoid of the electromagnetic relief valve 60 is decreased according to the increase of the vehicle speed. As a result, the control pressure of the oil introduced into the reaction force cylinder chamber 33 through the introduction port 40 by the electromagnetic relief valve 60 is increased in accordance with the increase in the vehicle speed, and the reaction force piston 35 causes the axial thrust corresponding to the control pressure. Is pressed against the engagement ball 36 to increase the manual torque for relatively rotating the sleeve valve member 21 and the rotor valve member 22. When the vehicle speed rises in this way, a control pressure corresponding to the vehicle speed is applied to the reaction force piston 35, and the vehicle speed sensitivity in which the manual torque increases in proportion to the increase in the vehicle speed is brought about.

In the above-described embodiment, an example in which the control pressure introduced into the reaction force cylinder chamber 33 is controlled in proportion to the vehicle speed has been described, but this control pressure is controlled by the steering wheel rotation angle or the steering wheel rotation speed in addition to the vehicle speed. Of course, you can also do it.

Further, in the above-described embodiment, an example in which the reaction force piston 35 of the reaction force mechanism is moved in the axial direction of the servo valve 20 has been described, but even if the reaction force piston is moved in the radial direction of the servo valve, It is possible to perform the same manipulating force control as. Instead of the electromagnetic relief valve 60, an electromagnetic control valve that changes the throttle area of the variable throttle may be used.

<Effects of the Invention> As described above, the present invention controls the supply pump driven by the automobile engine and the pressure oil discharged from the supply pump to a predetermined flow rate required for the power take-up device to bypass the excess flow. A first flow rate control valve, a second flow rate control valve that controls the bypass flow rate bypassed by the first flow rate control valve to a constant flow rate and bypasses the surplus flow to the low pressure side, and the second flow rate control valve An electromagnetic pressure control valve that controls a constant flow rate of pressure oil controlled by a valve to a control pressure according to the vehicle speed, a relief valve that escapes to a low pressure side when this control pressure exceeds a predetermined pressure, and the electromagnetic pressure Since the control pressure controlled by the control valve is introduced into the reaction force mechanism, the spool in the electromagnetic pressure control valve is locked by dust or the like, or On the way Even if the oil flow is stopped due to clogging of dust and the like, the pressure of the oil above the predetermined pressure does not act on the reaction mechanism, so there is an advantage that the state of manual steering can be avoided.

[Brief description of drawings]

1 is a diagram showing a hydraulic system diagram together with a cross-sectional view of a power steering apparatus showing an embodiment of the present invention. 11 ... Output shaft, 20 ... Servo valve, 24 ... Input shaft, 33 ... Reaction force cylinder chamber, 35
...... Reaction force piston, 50 ...... Supply pump, 51 ...... First flow control valve, 55 ...... Second flow control valve, 60 ...... Electromagnetic relief valve, 80 ...... Relief valve.

Claims (1)

[Claims] 1. A servo valve which is operated based on relative rotation between an input shaft and an output shaft to control supply and discharge of pressure oil to and from a power cylinder, and a reaction force mechanism which changes a steering wheel torque according to a vehicle speed. In a steering control device for a power steering apparatus, a supply pump driven by an engine and a pressure oil discharged from the supply pump are controlled to a predetermined flow rate required for the power steering apparatus to bypass an excess flow. Flow control valve, a second flow control valve that controls the bypass flow rate bypassed by the first flow control valve to a constant flow rate and bypasses the surplus flow to the low pressure side, and the second flow control valve The electromagnetic pressure control valve that controls the pressure oil with a constant flow rate to a control pressure according to the vehicle speed, the relief valve that escapes to the low pressure side when this control pressure becomes equal to or higher than a predetermined pressure, and the electromagnetic pressure control valve Controlled Steering force control device for a power Hebito device comprising constituted by means for introducing the control pressure in the reaction force mechanism.