JPS61218481A - Steering force controller for power steering - Google Patents

Abstract

PURPOSE:To make a manual torque gear producing pressure characteristic at high-speed driving into the ideakustic one, by constituting the pressure oil divided to the side of a reaction chamber by a flow dividing control valve to be controlled with each action of a solenoid relief valve and a variable throttle valve according to a car speed. CONSTITUTION:A flow rate Q0 of pressure oil to be discharged out of a feed pump 60 is controlled to a constant flow rate Q by a flow control valve 61, and this flow is divided to both sides of a servo valve 30 and a reaction chamber 56 by a flow divind control valve 65. In a state of a car speed being low, a maximum current is fed to a solenoid relief valve 70 via a control circuit 81 where a car speed signal V is inputted, setting relief setting pressure to zero, and a variable throttle valve 100 is made to come into a state of being fully opened. And, when the car speed exceeds the specified value, the relief setting pressure of the solenoid relief valve 70 increases according to a rise in the car speed, making reaction oil pressure PR go up. With this, the setting pressure operates the variable throttle valve 100, pressurizing a plunger 54 of a reaction mechanism, it is made to work so as make operation of a steering wheel heavier.

Description

[Detailed description of the invention] <Field of application in industry> The present invention provides a power steering system equipped with a reaction force mechanism that supplies control pressure according to vehicle speed, etc., and changes steering torque according to vehicle speed, etc. The present invention relates to a steering force control device for a steering device.

<Prior Art> It is known that a control pressure proportional to the vehicle speed or the like is introduced into a reaction force mechanism to control the steering force of the power steering device according to the vehicle speed or the like. In this type of 817, the hydraulic pressure introduced into the reaction force mechanism is controlled using pressure oil in a high pressure line connecting the power steering device and the supply pump.

<Problems to be solved by the invention> In general, this type of control device lowers the hydraulic pressure applied to the reaction force mechanism when running at low speeds when steering pressure is required, and conversely lowers the hydraulic pressure applied to the reaction force mechanism when running at high speeds when steering pressure is not needed at all. need to be higher.

Conventionally, the hydraulic pressure applied to this reaction force mechanism is controlled by an electromagnetic pressure control valve based on signals such as vehicle speed, regardless of steering pressure. As shown in Fig. 4, the manual torque-gear generated pressure characteristics resulting from this change are such that the characteristics during high-speed driving only shift in parallel to the characteristics during low-speed driving, as shown by the two-dot chain line, and the characteristics during high-speed driving differ from those during low-speed driving. The tilt cannot be changed freely. Therefore, there is a problem in that even if the steering wheel is turned in a state where the reaction oil pressure is high, the steering force does not change much. Ideally, the characteristics should have a large slope as shown by the solid line during high-speed running in FIG.

In view of the above-mentioned conventional problems, the present invention makes the manual torque-gear generation pressure characteristic during high-speed running ideal with a large slope, and clarifies the change in steering force.

<Means for Solving the Problems> The present invention provides a servo valve that is operated based on the relative rotation between the input shaft and the output shaft and controls the supply and discharge of pressure oil to the power cylinder, and a handle that is operated based on the relative rotation between the input shaft and the output shaft. In a steering force control device for a power steering device equipped with a reaction force mechanism that changes torque, a diversion system that divides a constant flow of pressure oil discharged from a supply pump into the servo valve side and the reaction chamber side of the reaction force mechanism. A control valve, a communication passage that communicates a passage on the servo valve side and a passage on the reaction chamber side via a fixed throttle, and an electromagnetic relief valve that is provided in the passage on the reaction chamber side and is controlled according to vehicle speed, etc. Above, a variable throttle valve is provided in series with the electromagnetic relief valve, which operates according to the relief setting pressure of the electromagnetic relief valve.

<Function> In the present invention, a constant flow rate of pressure oil discharged from the supply pump is divided so as to be supplied to the servo valve side and the reaction force chamber side by the division/flow II7 control valve. The pressure oil diverted to the reaction force chamber enters the electromagnetic relief valve and sets the relief pressure according to the vehicle speed, etc.
The reaction oil pressure introduced into the reaction force chamber is controlled by a variable throttle valve operated by this relief setting pressure, and this reaction oil pressure is controlled by a fixed restriction in the communication passage → the gear generation pressure on the J-bo valve side. The hydraulic pressure increases as the differential pressure between the hydraulic pressure and the reaction pressure increases by 1, and the hydraulic pressure supplied to the reaction force chamber is controlled to a high pressure at high speeds to control the steering force.

<Examples> Examples of the present invention will be described below based on the drawings. In FIG. 1, numeral 1 is a housing main body forming the main body of the power steering device, and 12 is a valve housing fixed to the housing main body 11. In FIG. A pinion shaft (output shaft) 21 is rotatably supported in the housing main body II and the valve housing 12 via a pair of bearings 13 and 14, and the pinion shaft 2I is slidable in a direction crossing the pinion shaft 2I. The rack teeth 22a of the possible rack shafts 22 are in mesh. This rack shaft 22 is connected to a piston of a power cylinder (not shown), and both ends thereof are connected to steering wheels via a required steering link mechanism.

A servo valve 30 is housed in the hole of the valve housing 12. The servo valve 30 mainly includes a rotary valve member 31 formed integrally with an input shaft 23 as a steering shaft, and a sleeve valve member 32 fitted to the outer circumference of the rotary valve member 31 concentrically and relatively rotatably. It is used as a component. The rotary valve member 31 is flexibly connected to the pinion shaft 21 via a torsion bar 24 whose one end is connected to an input shaft 23 integral therewith. Further, on the outer periphery of the rotary valve member 31, a plurality of land portions and groove portions (not shown) extending in the axial direction are formed at equal intervals, and a communication path that communicates from the bottom of the groove to the inner peripheral portion. 37 are drilled.

The input shaft 23 is provided with a passage 39 that communicates the inner peripheral portion with the low pressure chamber 38 within the valve housing 12 . On the other hand, a plurality of lands and grooves extending in the axial direction are formed at equal intervals on the inner periphery of the sleeve valve member 32, and distribution holes 40° 41 are provided that open from each groove to the outer periphery of the sleeve valve member 32. ing. When the control valve is in the neutral state, the pressure fluid supplied from the supply boat 35 flows equally into the grooves on both sides of the land portion, and flows out from the low pressure chamber 38 to the discharge boat 36 via the communication passage 37 and the passage 39. In this case, both distribution boats 33, 34 are at low and equal pressure, so the power cylinder is not activated. When the control valve deviates from the neutral state, pressure oil is supplied from the supply boat 35 to one distribution hole 40 or 41, and fluid discharged from the power cylinder flows into the other distribution hole 41 or 40, and the connection is established. The liquid is discharged into the discharge boat 36 through a passage 372, a passage 39, and a low pressure chamber 38.

The reaction force mechanism is as follows. A protrusion 50 that protrudes on both sides in the radial direction is formed at the end of the rotary valve member 31 on the binion shaft 21 side. A fitting groove 51 is formed into which the fitting groove 51 is loosely fitted so as to be rotatable several angles.

A tapered engagement groove 52 is formed on the outer peripheral surface of the protrusion 50, and an insertion hole 53 is formed in the radial direction in the pinion shaft 21 at a position corresponding to the engagement groove 52 when the control valve is in the neutral state. has been done. A plunger 54 is slidably inserted in the insertion hole 53 in the radial direction, and an annular groove 55 is formed to guide hydraulic fluid to the rear of the plunger 54.

The insertion hole 53 and the annular groove 55 constitute a reaction force chamber 56. Reference numeral 58 is a boat that introduces pressure fluid from a pump controlled according to the vehicle speed, etc., and 57 is a passage that communicates the boat 58 with the annular groove 55.

The reaction force mechanism configured as described above is a so-called radial type, but may also be a thrust type configured to apply a reaction force in the axial direction.

In FIG. 2, 6I is a flow control valve that controls the flow rate 00 of the pressure oil discharged from the supply pump 60 driven by the automobile engine to a constant flow rate Q. This flow, quantity control valve 6
I is operated by a metering orifice 62 and a bypass valve 64 that is operated according to the front and rear pressure of this metering orifice 62 and controls the opening of a bypass passage 63 communicating with the low pressure side so as to keep this front and rear pressure constant. It is configured. Incidentally, if the supply pump is of a constant speed motor-driven type and discharges a constant flow rate, the flow rate control valve 61 is not necessary.

Reference numeral 65 denotes a flow divider that is connected to the high pressure side of the flow rate control valve 61. This branch control valve 65 is
The flow rate Q is controlled by the servo valve 3 using the differential pressure across the fixed throttle 68 and the control spool 67 operated by a spring.
The flow rate OG is divided into the passage 45 on the 0 side, and the flow rate OR is divided into the passage 46 on the reaction force chamber 56 side.

Further, the passages 45 and 46 are communicated through a communication passage 90 having a fixed throttle 91. Further, in the passage 46 on the side of the reaction force chamber 56, an electromagnetic relief valve 70 that is controlled according to the vehicle speed, etc.
And, immediately before this electromagnetic relief valve 70, an electromagnetic relief valve 7 is installed.
Variable throttle valve 100 that operates according to the relief setting pressure of 0
is located. In FIG. 2, 64 indicates a power cylinder.

As shown in FIG. 3, the electromagnetic relief valve 70 has a solenoid 71 supplied with a current value according to a vehicle speed signal V from a solenoid control circuit 81 controlled by a computer.
, a relief pressure setting spring 74 whose spring load is changed by the action of this solenoid 71, and a ball valve 73 that is pressed by this spring 74 and releases the reaction pressure PR to the low pressure side via the relief passage 72. has been done.

Next, the operation of the above configuration will be explained. The flow rate 00 of the pressure oil discharged from the supply pump is controlled to a constant flow rate Q by the flow control valve 61. The pressure oil controlled to have a constant flow rate Q is divided into the servo valve 30 side and the reaction force chamber 56 side by the flow control valve 65.

When the vehicle speed is low, the solenoid 7 of the electromagnetic relief valve 70
As a result, the spring load of the relief pressure setting spring 74 becomes substantially O, and the relief setting pressure becomes O, so that the variable throttle valve 100 adjusts between the train pressure of the electromagnetic relief valve 70 and the spring. It becomes fully open.

Therefore, the reaction oil pressure PI'l flows into the reservoir, and the reaction oil pressure PI'l is held at O. Therefore, when the input shaft 23 is rotated by operating the handle, the plunger 54 is easily pushed up, thereby causing the sleeve valve The member 32 and the rotor valve member 31 are rotated relative to each other, and the change in the gear generated pressure F'G with respect to the manual torque has the characteristics shown by the low-speed, stationary curve in FIG. 4, allowing light steering operation.

Furthermore, when the vehicle speed exceeds a predetermined value, the current value supplied to the solenoid 73 of the electromagnetic relief valve 70 is decreased in response to the vehicle speed signal V input to the control circuit 8I as the vehicle speed increases. As a result, the spring load of the relief pressure setting spring 74 is increased as the vehicle speed increases, and the reaction oil pressure P
R is increased, and at the same time, the variable throttle valve 100 is operated by the rise in the reaction oil pressure PR, thereby forming a throttle passage. Therefore, as the vehicle speed increases, the plunger 54 is pressed against the engagement groove 52 by a force corresponding to the reaction oil pressure P, and the sleeve valve member 3
2 and the rotary valve member 31 are rotated relative to each other, making the handle operation difficult. Then, at high speed, when the handle is turned in, the gear generation pressure PG on the servo valve 30 side increases. In response to this increase in gear generation pressure PG, the communication passage 9
Gear generation pressure PG and reaction oil pressure Pl' with fixed throttle 91 of 0
The differential pressure with 1 increases by 1, and the variable throttle valve 100
The flow rate g passes through the fixed throttle 91, and the throttle action of the variable throttle valve 100 increases the reaction oil pressure PR in accordance with the gear generation pressure PG. As a result, the high speed (
As shown in the curve of the present invention), the slope of the manual torque characteristic is changed to a greater degree than the conventional characteristic in accordance with the gear generation pressure PG, thereby making it clearer when turning the steering wheel at high speed.

Incidentally, the variable throttle valve 100 can perform the same function even if it is provided on the drain side of the electromagnetic relief valve 70.

<Effects of the Invention> As described above, the present invention divides a constant flow of pressure oil from the supply pump into the servo valve side and the reaction force chamber side using the distribution control valve, and uses a fixed throttle between the distribution passages. In the passage on the reaction force chamber side, there is an electromagnetic relief valve that is controlled according to the vehicle speed, etc., and in series with this electromagnetic relief valve, there is a variable valve that is operated by the relief setting pressure of the electromagnetic relief valve. A throttle valve is provided, and the flow rate passing through the variable throttle valve is increased according to the pressure generated by the gear during high-speed running, thereby increasing the reaction oil pressure, so the slope of the manual torque during high-speed steering is free. This has the effect of providing a feeling of responsiveness when steering.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an embodiment of a power steering device, Fig. 2 is a hydraulic system diagram of the present invention, Fig. 3 is a sectional view of the main part of an electromagnetic relief valve, and Fig. 4 is a curve diagram of steering characteristics. It is. 21... Pinion shaft, 23... Input shaft, 30...
Servo valve, 56... reaction force chamber, 65... branch control valve,
70... Solenoid relief valve, 90... Communication path, 91...
...Fixed throttle, 100...Variable throttle valve.

Claims (1)

[Claims] Steering of a power steering device equipped with a servo valve that is activated based on the relative rotation of the input shaft and output shaft to supply and discharge pressure oil to the power cylinder, and a reaction force mechanism that changes the steering torque according to vehicle speed, etc. In a force control device, a flow control valve that divides a constant flow of pressure oil discharged from a supply pump into a servo valve side and a reaction chamber side of a reaction force mechanism, a passage on the servo valve side and a passage on the reaction chamber side an electromagnetic relief valve that is controlled according to the vehicle speed, etc. provided in the passage on the reaction chamber side, and a relief setting pressure of the electromagnetic relief valve that is connected in series with the electromagnetic relief valve. A steering force control device for a power steering device, characterized in that it is equipped with a variable throttle valve that operates according to.