JPH0811538B2 - Steering force control device for power steering device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a power steering apparatus including a reaction force mechanism that supplies a control pressure according to a vehicle speed or the like and changes a steering wheel torque according to the vehicle speed or the like. The present invention relates to a steering force control device.

<Prior Art> It is known that a control pressure proportional to a vehicle speed or the like is introduced into a reaction force mechanism to control the steering force of a power steering apparatus according to the vehicle speed or the like. In this type of device, a constant flow rate of the pressure oil discharged from the supply pump is diverted to the servo valve side and the pressure chamber side of the reaction force mechanism by a shunt control valve, and the vehicle speed etc. provided in the passage on the reaction force chamber side is divided. The hydraulic pressure introduced into the reaction force mechanism is controlled by the electromagnetic throttle valve that is controlled in accordance with. In addition, a communication passage that connects the passage on the servo valve side and the passage on the reaction force chamber side via a fixed throttle is provided to respond to the increase in the pressure generated by the servo valve when the handle is cut at high speed. There is a configuration in which the reaction force hydraulic pressure is increased by the flow rate passing through the fixed throttle of the communication passage to make the feeling of response clear.

<Problems to be Solved by the Invention> In the above conventional configuration, the flow rate q in the communication passage increases in proportion to the gear generation pressure PG. Therefore, the electromagnetic throttle valve that does not require a reaction force is fully open and stationary, and at low speeds the gear pressure is used up to 70 to 80 kgt / cm ^2, so the flow rate q becomes too large and the flow velocity at the fixed throttle becomes extremely high. . Therefore, due to the flow rate q flowing through the fixed throttle into the leaf passage, a shoe sound (passing sound of pressure fluid) is generated in the fixed throttle portion.

<Means for Solving Problems> The present invention has been made to solve the above-mentioned conventional problems, and the structure thereof is operated based on the relative rotation of the input shaft and the output shaft. In the steering force control device of the power steering system, which has a servo valve that supplies and discharges pressure oil to and from the vehicle, and a reaction force mechanism that changes the steering wheel torque according to the vehicle speed, etc. A flow control valve for controlling the flow rate to the servo valve and the reaction force mechanism to divide the flow rate, a servo valve operated based on the relative rotation of the input shaft and the output shaft to supply and discharge the pressure oil to the power cylinder, the vehicle speed, etc. In the steering force control device of the power steering device equipped with a reaction force mechanism that changes the steering wheel torque in accordance with the above, the constant amount of pressure oil discharged from the supply pump is supplied to the servo valve side and the reaction force chamber side of the reaction force mechanism. A diversion control valve for diversion to An electromagnetic throttle valve provided in the passage on the reaction force chamber side and controlled according to the vehicle speed and the like is provided, and the diversion control valve has a spring for pressure balancing the spool valve and a piston for changing the spring load of the spring. However, a pressure oil circuit for controlling the piston by the pressure generated by the gear from the passage on the servo valve side is provided.

<Operation> In the present invention, the gear generated pressure is applied to the piston of the diversion control valve, the spring load of the spring that presses the spool valve of the diversion control valve is changed, and the reaction force hydraulic pressure is controlled according to the gear generated pressure.

<Examples> Examples of the present invention will be described below with reference to the drawings. First
In the figure, 11 is a housing main body that forms the main body of the power steering apparatus, and 12 is a valve housing fixed to the housing main body 11. This housing body 11 and valve housing 12
A pinion shaft (output shaft) 2 via a pair of bearings 13 and 14
1 is rotatably supported and the pinion shaft 21 has rack teeth of a rack shaft 22 slidable in a direction intersecting with the pinion shaft 21.
22a meshes. The rack shaft 22 is connected to the piston of the power cylinder 15 (see FIG. 3), and both ends thereof are connected to the steered wheels via a required steering link mechanism.

A servo valve 30 is housed in the valve hole of the valve housing 12. The servo valve 30 includes a rotary valve member 31 formed integrally with an input shaft 23 as a steering shaft, and the rotary valve member 31.
A sleeve valve member 32, which is concentrically and relatively rotatably fitted around the outer circumference of 31, is a main constituent member. Rotary valve member
Reference numeral 31 is flexibly connected to the pinion shaft 21 via a torsion bar 24 having one end connected to an input shaft 23 integrated with the pinion shaft 21.

Further, although not shown on the outer periphery of the rotary valve member 31,
A plurality of lands extending in the axial direction and a groove are formed at equal intervals, and a communication passage 37 is formed so as to communicate from the groove bottom to the inner peripheral portion. The input shaft 23 is provided with a passage 39 that connects the inner peripheral portion and the low pressure chamber 38 in the valve housing 12. On the other hand, on the inner circumference of the sleeve valve member 32, a plurality of brand portions and groove portions extending in the axial direction are formed at equal intervals,
Distribution hole 4 that opens from the groove to the outer circumference of the sleeve valve member 32
0,41 are provided. If the servo valve is in the neutral state, the pressure fluid supplied from the supply port 35 flows evenly in the groove portions on both sides of the land portion, passes through the communication passage 37 and the passage 39, and then the low pressure chamber 38.
From the discharge port 36. In this case, both distribution ports
The power cylinder 15 is not operated because the pressures of 33 and 34 are low and equal. When the servo valve 30 deviates from the neutral state, pressure oil is supplied to the one distribution hole 40 or 41 from the supply port 35, and the power cylinder is supplied to the other distribution hole 41 or 40.
The fluid discharged from 15 flows in and is discharged to the discharge port 36 via the communication passage 37, the passage 39, and the low pressure chamber 38.

The reaction force mechanism is as follows. As shown in FIG. 2, the rotary valve member 31 is provided at its end on the pinion shaft 21 side with protrusions 50 protruding radially on both sides.
The pinion shaft 21 corresponding to the above is formed with a fitting groove 51 into which the protrusion 50 is loosely fitted so as to be rotatable about the axis of the input shaft 23 by several degrees.

Insertion holes 53 are formed on both sides of the projection 50 on the pinion shaft 21, and the plungers are respectively inserted into the insertion holes 53.
54 is slidably connected. The plunger 54 is projected forward by the hydraulic pressure introduced into the reaction force chamber 55 formed at the rear of the plunger 54. The plunger 54 is clamped from both sides thereof, and its forward end is a large diameter portion formed on the plunger 54.
It is regulated by 54a. 57 is a port for introducing hydraulic pressure according to the vehicle speed, 58 is a passage, and 59 is an annular groove that connects the passage 58 with the reaction chamber 55.

The reaction mechanism having the above-mentioned structure applies hydraulic pressure in the direction in which the protrusions 50 are rotated by the plungers 54 provided on both sides of the protrusion 50, but the radial system that presses the plunger in the radial direction. It may be a thrust type one that is pressed by or in the axial direction.

FIG. 3 shows an embodiment of the present invention, and 60 is a supply pump driven by an automobile engine. Reference numeral 61 is a flow rate control valve for controlling the flow rate Q ₀ of the pressure oil discharged from the supply pump 60 to a constant flow rate Q. This flow control valve 61 is operated in accordance with the metering orifice 62 and the front-rear pressure of the metering orifice 62, and a bypass valve for controlling the opening of a bypass passage 63 communicating with the low pressure side so as to always keep the front-rear pressure constant. It is composed of 64. When the supply pump 60 is driven by a constant speed motor, the flow rate control valve 61 is not necessary because a constant flow rate Q is discharged.

1 is connected to the high-pressure side of the flow control valve 61, and the flow rate QG from the supply pump 60 to the servo valve 30 side and the flow rate QR to the reaction force chamber 55 side at a constant shunt ratio. It is a diversion control valve.

This diversion control valve 1 is an inlet port 2 for introducing a constant flow rate Q of pressure fluid from the supply pump 60, and a servo valve which moves the pressure fluid introduced from this inlet port 2 by a spool valve 5 at a constant diversion rate. It has a first outlet port 3 flowing into the chamber 30 via a passage 45 and a second outlet port 4 flowing into the reaction force chamber 55 via a passage 46.

Further, pressure chambers 9a, 9b, 9c are formed in the inner hole of the valve housing 18 in which the spool valve 5 is slidably fitted. The pressure chamber 9a communicates with the pressure chamber 9b via a communication passage 11 provided in the spool valve 5, and the pressure chamber 9b communicates with the pressure chamber 9c via the orifice 6 and the shaft hole 8 of the spool valve 5. Reference numeral 7 is a first spring for pressing the spool valve 5 to the left in FIG. 3, and the spool valve 5 is moved by the balance of the front-rear pressure of the orifice 6 and the pressing force of the first spring 7.

12 is a cylinder, and in FIG. 3, a valve housing 18
Is formed at the right end of the. A piston 13 and a piston rod 14 integrated with the piston 13 are fitted in the cylinder 12 so as to be movable in the same direction as the spool valve 5, and the second spring 15 causes the piston 13 to move to the right end in FIG. Pressing in the home position direction. Further, one end of the first spring 7 is in contact with the tip of the piston rod 14.
Reference numeral 19 is a stopper portion that defines the forward movement end of the piston 13.

At the rear end of the cylinder 12, an input port for the gear generation pressure
16 is provided, and is connected to the passage 45 on the servo valve 30 side via the passage 17.

Reference numeral 70 denotes an electromagnetic throttle valve provided in the passage 46 on the reaction force chamber 55 side, which controls the flow rate QR on the reaction force chamber 55 side according to the vehicle speed or the like to drain to the low pressure side.

Next, the operation of the above configuration will be described. Supply pump 60
The diversion control valve 1 diverts the pressure oil having a constant flow amount Q from the flow amount into a flow amount QG to the servo valve 30 side and a flow amount QR to the reaction force mechanism side.

When the vehicle speed is low, no electric current is supplied to the solenoid of the electromagnetic throttle valve 70, so the solenoid valve 70 is fully open.
The flow rate QR divided into two is released to the low pressure side without resistance. Therefore, the reaction force hydraulic pressure acting on the plunger 54 of the reaction force mechanism is maintained at 0, so that when the input shaft is rotated by the handle operation, the plunger 54 is easily pushed up, whereby the sleeve valve member 32 and the rotary valve member. 31 and 31 rotate relative to each other, and a light steering wheel operation can be performed like the manual torque shown by the curve at low speed in FIG.

When the vehicle speed exceeds a predetermined value, the current value supplied to the solenoid of the electromagnetic throttle valve 70 increases linearly as the vehicle speed increases. As a result, the opening degree of the electromagnetic throttle valve 70 is narrowed to increase the reaction force hydraulic pressure PR. Therefore, the plunger 54 according to the increase of the vehicle speed increases the pressing force against the projection 50 by the force according to the reaction force hydraulic pressure PR, and moves in parallel with the low speed like the manual torque shown by the curve at the high speed in FIG. To increase the steering force.

Further, at high speed, when the handle is turned, the gear generation pressure PG of the servo valve 30 increases. This gear generation pressure PG is passed through the passage 17 to the cylinder 12 of the diversion control valve 1.
Is guided to the inlet port 16 and the piston 13 is moved in the forward direction (left direction in FIG. 3) by the increase in the gear generation pressure PG.
The amount of forward movement of the piston 13 presses the first spring 7 in contact with the tip end surface of the piston rod 14 to increase the spring load of the first spring 7.

By increasing the spring load of the first spring 7, the flow rate QR on the reaction force chamber 55 side increases in proportion to the increase of the gear generation pressure PG as shown in FIG. As shown by the curve, it is tilted more than the curve at high speed, making the feel of the handle when turning it clear. still,
In Fig. 4, point A is the piston due to the gear generation pressure PG.
13 is the point at which the operation is started, and point B is the point at which the piston 13 contacts the stopper 19 and the forward movement is restricted.

<Effects of the Invention> As described above, according to the present invention, the flow control valve for dividing the pressure fluid is provided on the side of the reaction force chamber on the servo valve side, and the spring of the spring that presses the spool valve of the flow control valve. By changing the load and increasing the pressure generated by the gear, the flow rate on the reaction force chamber side is increased, and the reaction force oil when the handle is turned at high speeds is increased to clarify the feeling of response.
This is to solve the problem of shoe noise in the communication passage, which has a structure in which the passage on the servo valve side and the passage on the reaction force chamber side are communicated with each other through a fixed throttle as in the prior art.

[Brief description of drawings]

The drawings show an embodiment of the present invention. Fig. 1 is a sectional view of a power steering apparatus, Fig. 2 is a sectional view taken along the line II-II of Fig. 1, Fig. 3 is a hydraulic system diagram of the present invention, and Fig. 4 Is a reaction force chamber side flow rate characteristic chart according to the present invention, and FIG. 5 is a steering force characteristic chart according to the present invention. 1 ... Flow control valve, 5 ... Spool valve, 7 ... First spring, 12 ... Cylinder, 13 ... Piston, 17 ... Passage, 21 ... Pinion shaft, 23 ... Input shaft, 30 ... … Servo valve, 55… Reaction chamber, 70… Electromagnetic throttle valve.

Claims (1)

[Claims] 1. A servo valve which is operated based on relative rotation between an input shaft and an output shaft to supply and discharge pressure oil to and from a power cylinder,
In a steering force control device of a power steering device equipped with a reaction force mechanism that changes the steering wheel torque according to the vehicle speed, etc., a constant flow rate of pressure oil discharged from a supply pump is applied to the servo valve side and the reaction force chamber of the reaction force mechanism. And a solenoid valve that is controlled in accordance with the vehicle speed and the like provided in the passage on the reaction force chamber side, and the diversion control valve includes a spring for pressure balancing the spool valve, A steering force control device for a power steering device, comprising: a piston for changing a spring load of a spring; and a pressure oil circuit for controlling the piston by a gear generation pressure from a passage on the servo valve side. .