JPS6325176A - Steering force control device for power steering device - Google Patents

Abstract

PURPOSE:To suppress noise in a communication passage by causing spring loads of a spring pressing a spool valve of a divided flow control valve to vary to control reactional oil pressures according to pressures generated by a gear. CONSTITUTION:Pressure chambers 9a through 9c are formed in a hole of a valve housing 18 in which a spool valve 5 is slidably fitted. The pressure chamber 9a communicates with the pressure chamber 96 via a communication passage 11 provided in the spool valve 5 and the pres. sure chamber 9b communicates with the pressure chamber 9c via both an orifice 6 and an axial hole 8 of the spool valve 5. The spool valve 5 is displaced by the balance between pressures at front and back of the orifice 6 and a 1st spring 7. A piston 13 having an integral piston rod 14 is fitted movably in the same direction with that of the spool valve 5 in a cylinder 12 and is pressed toward an original position at a right end by means of a 2nd spring 15.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a power steering device 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.

<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 device, a constant flow rate of pressurized oil discharged from a supply pump is divided into a servo valve side and a reaction chamber side of a reaction force mechanism by a flow control valve, and a vehicle speed control valve is installed in a passage on the reaction force chamber side. The hydraulic pressure introduced into the reaction force mechanism is controlled by an electromagnetic throttle valve that is controlled according to the following conditions. In addition, a communication passage is provided between the passage on the servo valve side and the passage on the reaction force chamber side through a fixed throttle, so that when the handle is turned at high speed,
There is a configuration in which the reaction oil pressure is increased by the flow rate passing through a fixed throttle in the communication passage in response to an increase in the gear-generated pressure of the servo valve, thereby making the response clearer.

<Problems to be Solved by the Invention> In the conventional configuration described above, the flow rate q of the communication passage increases in proportion to the gear generation pressure PG. Therefore, when the electromagnetic throttle valve, which does not require reaction force, is fully open and at low speed, the gear generated pressure is used up to 70 to 80 kgt/cm2, so the flow rate q becomes too large, and the flow velocity in the fixed throttle part becomes extremely high.

Therefore, due to the flow rate q flowing through the fixed throttle and into the relief passage, a hissing sound (passage sound of pressure fluid) is generated in the fixed throttle.
occurs.

Means for Solving the Problems> The present invention has been made to solve the above-mentioned problems of the conventional art. In the steering force control device of a power steering device, which is equipped with 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 depending on the vehicle speed, etc., a constant flow of pressure oil discharged from a supply pump is used. a flow control valve that controls and diverts the flow of oil to the servo valve and the reaction force mechanism, a servo valve that is operated based on the relative rotation between the input shaft and the output shaft and supplies and discharges pressure oil to the power cylinder, and a vehicle speed, etc. In a steering force control device for a power steering device equipped with a reaction force mechanism that changes steering wheel torque according to and an electromagnetic throttle valve that is provided in the passage on the reaction force chamber side and is controlled according to the vehicle speed, etc., and the diversion control valve includes a spring that balances the pressure of the spool valve, and a spring that balances the pressure of the spool valve. The piston has a piston that changes a spring load, and is provided with a pressure oil circuit that controls the piston using gear-generated pressure from a passage on the servo valve side.

Function> The present invention applies gear-generated pressure to the piston of the diversion control valve, changes the spring load of the spring that presses the spool valve of the diversion control valve, and controls the reaction oil pressure according to the gear-generated pressure. .

Embodiments Hereinafter, embodiments of the present invention will be described based on the drawings. In FIG. 1, reference numeral 11 indicates a housing main body forming the main body of the power steering device, and reference numeral 12 indicates a valve housing fixed to the housing main body 11. A binion shaft (output shaft) 21 is rotatably supported within the housing body 11 and the valve housing 12 via a pair of bearings 13 and 14, and the binion shaft 21 is slidable in a direction crossing the binion shaft 21. 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 15 (see FIG. 3), and both ends thereof are connected to steering wheels via a required steering link mechanism.

A servo valve 30 is housed within the valve hole of the valve housing 12. The servo valve 30 is connected to the input shaft 23 as a steering shaft.
The main components are a rotary valve member 31 formed integrally with the rotary valve member 31, and a sleeve valve member 32 fitted concentrically and relatively rotatably to the outer periphery of the rotary valve member 31. 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, although not shown, on the outer periphery of the rotary valve member 31,
A plurality of land portions and groove portions extending in the axial direction are formed at equal intervals, and a communication passage 37 communicating from the groove bottom to the inner peripheral portion is bored. A passage 39 that connects the input shaft 23 with the inner peripheral portion and the low pressure chamber 38 in the valve housing 12.
is provided. On the other hand, a plurality of lands and grooves extending in the axial direction are formed at equal intervals on the inner circumference of the sleeve valve member 32, and distribution holes 40, 41 are provided that open from each groove to the outer circumference of the sleeve valve member 32. There is.

When the servo 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 port 36 via the communication passage 37 and the passage 39. In this case, since both distribution ports 33 and 34 are at low and equal pressure, the power cylinder 15
is not activated. When the servo valve 30 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 15 flows into the other distribution hole 41 or 40. , communication path 372
Passage 39. It is designed to be discharged into a discharge boat 36 via a low pressure chamber 38.

The reaction force mechanism is as follows. As shown in FIG. 2, a protrusion 50 is formed at the end of the rotary valve member 31 on the pinion shaft 21 side, and the protrusion 50 protrudes from both sides in the radial direction. A fitting groove 51 into which the part 50 is loosely fitted so as to be rotatable several degrees around the axis of the input shaft 23
is formed.

Insertion holes 53 are formed in the pinion shaft 21 on both sides of the protrusion 50, and plungers 54 are slidably inserted into each of the insertion holes 53. The plunger 54 is projected forward by hydraulic pressure introduced into a reaction chamber 55 formed at the rear thereof, and holds the protrusion 50 from both sides thereof, and its forward end is connected to a large diameter portion formed in the plunger 54. 54a.

57 is a boat for introducing hydraulic pressure according to the vehicle speed, 58 is a passage, and 59 is an annular groove that communicates this passage 58 with the reaction force chamber 55.

The reaction force mechanism configured as described above applies hydraulic pressure in the direction of rotating the protrusion 50 by the plungers 54 provided on both sides of the protrusion 50, but it is a radial type in which the plunger is pressed from the radial direction. Alternatively, a thrust type that presses in the axial direction may be used.

FIG. 3 shows an embodiment of the invention, where 60 is a supply pump driven by an automobile engine. Reference numeral 61 denotes a flow rate control valve that controls the flow of pressure oil discharged from the supply pump 60 to a constant flow rate Q. This flow rate control valve 61 is operated according to the metering orifice 62 and the front and back pressure of this metering orifice 62, and a bypass passage 63 that communicates with the low pressure side so as to keep this front and rear pressure constant at all times.
It is constituted by a bypass valve 64 that controls the opening of the valve. Incidentally, when the supply pump 60 is driven by a constant speed motor, a constant flow rate Q is discharged, so the flow rate control valve 61 is not necessary.

1 is connected to the high pressure side of the flow rate control valve 61, and supplies a constant flow rate of pressure fluid ff1Q from the supply pump 60 to the servo valve 30 side at a constant rate of division, and a flow rate OR to the reaction force chamber 55 side. This is a diverter control valve that allows the flow to flow.

This diversion control valve 1 includes an inlet boat 2 that introduces pressure fluid at a constant flow rate Q from the supply pump 60, and a servo valve that divides the pressure fluid introduced from the inlet boat 2 at a constant rate by moving a spool valve 5. 30 via a passage 45, and a second output robot 4 which allows the flow to flow to the reaction force chamber 55 via a passage 46.

Further, a pressure chamber 9a is provided in the inner hole of the valve housing 18 into which the spool valve 5 is slidably fitted.

9b and 9C are formed. 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 denotes a first spring that presses the spool valve 5 to the left in FIG. 3, and the spool valve 5 is moved by the balance between the longitudinal pressure of the orifice 6 and the pressing force of the first spring 7.

12 is a cylinder, and in FIG.
It is formed at the right end of 8. A piston 13 and a piston rod 14 integral with the bislon 13 are fitted in the cylinder 12 so as to be movable in the same direction as the spool valve 5, and a second spring 15 moves the piston 13 to the right end in FIG. It is pressed in the direction of the original position. Furthermore, one end of the first spring 7 is brought into contact with the tip of the piston rod 14 . Reference numeral 19 denotes a stopper portion that defines the forward movement end of the piston 13.

The rear end of the cylinder 12 has an input boat 16 for gear generation pressure, which is connected to a passage 45 on the side of the servo valve 3o and a passage 1.
It is connected via 7.

Reference numeral 70 designates an electromagnetic throttle valve provided in the passage 46 on the side of the reaction force chamber 55, which restricts and controls the flow MQR on the side of the reaction force chamber 55 in accordance with vehicle speed, etc., and trains it to the low pressure side.

Next, the operation of the above configuration will be explained. supply pump 60
A constant flow MQ of pressure oil is divided by a flow control valve 1 into a flow i0G to the servo valve 30 side and a flow rate QR7 to the reaction force mechanism side.

When the vehicle speed is low, no current is supplied to the solenoid of the electromagnetic throttle valve 70, so it is fully open, and the passage 4
The flow ff1OR divided into 6 is released to the low pressure side without resistance. Therefore, the reaction oil pressure acting on the plunger 54 of the reaction mechanism is maintained at O, so when the input shaft is rotated by operating the handle, the plunger 54 is easily pushed up.
As a result, the sleeve valve member 32 and the rotary valve member 31 rotate relative to each other, allowing light steering operation as shown by the manual torque curve at low speed in FIG.

Furthermore, when the vehicle speed exceeds a predetermined value, the current value supplied to the solenoid of the electromagnetic throttle valve 70 increases linearly in accordance with the increase in vehicle speed. This reduces the opening degree of the electromagnetic throttle valve 70 and increases the reaction oil pressure PR.

Therefore, as the vehicle speed increases, the pressing force of the plunger 54 against the protrusion 50 increases with a force corresponding to the reaction oil pressure PR.
As shown by the manual torque curve at high speeds in the figure, the steering force is increased by moving parallel to that at low speeds.

Furthermore, at high speeds, when the handle is turned in, the gear generation pressure PG of the servo valve 30 increases. This gear generation pressure PG is led to the inlet port 16 of the cylinder 12 of the branch control valve 1 through the passage 17, and the gear generation pressure PG
The rise causes the piston 13 to move forward (leftward in Figure 3).
move it to The amount of forward movement of the piston 13 presses the first spring 7 that is in contact with the distal end surface of the piston rod 14, increasing the spring load of the first spring 7.

By increasing the spring load of the first spring 7, the flow rate QR of the reaction force chamber 55 increases in proportion to the increase in the gear generation pressure PG as shown in FIG. As shown in the curve, the slope is greater than the curve at high speed,
To clarify the feeling of response when turning the handle.

In FIG. 4, point A is the point at which the piston 13 starts operating due to the gear generated pressure PG, and point B is the point at which the piston 13 contacts the stopper 19 and its forward movement is restricted.

-<Effects of the Invention> As described above, according to the present invention, a hydraulic cylinder is provided in the flow control valve that divides pressure fluid into the servo valve side and the reaction force chamber side, and gear generation pressure is introduced into this hydraulic cylinder. A piston is actuated, and the actuation of this piston changes the spring load of the spring that presses the spool valve of the flow dividing control valve, and the flow rate on the reaction force chamber side is increased due to the increase in the gear generation pressure, and the handlebar at high speeds. Since the purpose is to increase the reaction force pressure oil during cutting and make the feeling of response clear, the passage on the servo valve side and the passage on the reaction chamber side are communicated via a fixed throttle, as in the past. This solves the problem of hissing noise in the communication passage.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 is a cross-sectional view of the power steering device, FIG. 2 is a cross-sectional view taken along the line ■-■ in FIG. 1, FIG. 3 is a hydraulic system diagram of the present invention, and FIG. 5 is a reaction force chamber side flow rate characteristic diagram according to the present invention, and FIG. 5 is a steering force characteristic diagram according to the present invention. DESCRIPTION OF SYMBOLS 1... Diversion 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 force chamber,
70...Electromagnetic 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 the 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 force chamber side of the reaction force mechanism, and a vehicle speed etc. provided in a passage on the reaction force chamber side. an electromagnetic throttle valve that is controlled according to A steering force control device for a power steering device, comprising a pressure oil circuit that controls the piston using pressure.