JPS6299262A - Steering force control device of power steering device - Google Patents

Abstract

PURPOSE:To eliminate the need to regulate a working range of a varying throttle, by a method wherein a varying throttle, the opening of which is controlled by a gear-generated pressure along with steering of a servo valve, is inserted in the branch passage of a branch flow control valve, and a stationary throttle is situated in series to the varying throttle. CONSTITUTION:A flow rate control valve 61 is formed with a metering orifice 62 and a bypass valve 64, operated according to the front and the rear pressure of the orifice 62, and opened to control a bypass passage 63 communicated to the lower pressure side so as to hold the front and the rear pressure at a specified value. The high pressure side of the flow rate control valve 61 is connected to a branch flow control valve 65, and the valve 65 branches a flow rate Qc into the servo motor side and the reaction force chamber side by means of a control spool 67. A throttle valve 80 has a slide spool 83, and a branch throttle 84 is formed between the spool 83 and a valve hole. A stationary throttle 85 is located in series to the branch flow throttle 84, and controls a flow rate of pressure oil flowing through a branch passage 93.

Description

[Detailed Description of the Invention] <Industrial Field of Application> The present invention relates to a power steering device equipped with a reaction force mechanism that supplies hydraulic 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> Hydraulic pressure proportional to the vehicle speed, etc. is introduced into the reaction force mechanism to control the steering force of the power steering device according to the vehicle speed, etc. In particular, the hydraulic pressure introduced into the reaction force mechanism is introduced into the reaction force mechanism. It is known that the control is performed using pressure oil in a high pressure line connecting the intake device and the supply pump.

In general, this type of control device requires a low hydraulic pressure to be applied to the reaction force mechanism when driving at low speeds, which requires steering pressure, and a high hydraulic pressure at high speeds, when little steering pressure is required.

Conventionally, as shown in FIG. 11, the hydraulic pressure applied to the reaction force mechanism 100 is controlled by using a diversion control valve 130 that divides the fluid supplied from the pump 110 and whose flow rate is controlled to the power steering device 120 and the reaction force mechanism 100. In addition, an electromagnetic control valve 140 is provided that controls the amount of this diverted fluid released to the oil tank side based on signals such as vehicle speed. Furthermore, in order to increase the change in steering force during high-speed running, a variable steering pressure response throttle 150 is provided in the diverting passage 160 to increase the proportion of diverted flow toward the reaction force mechanism as the steering pressure increases.

<Problems to be Solved by the Invention> Steering pressure is introduced into one end of the variable throttle valve 150 and reaches the relief setting pressure at maximum load, so the spring constant of the spring 151 built into it is high. It is set. As a result, the valve body operating range X varies and the variable throttle area change of the branch control valve 130 also increases as shown in FIG. 12. Therefore, it is necessary to adjust the operating range X, which not only requires an adjustment mechanism but also involves troublesome assembly and adjustment, leading to a problem of increased costs.

<Means for Solving the Problems> The present invention aims to reduce variations in the flow rate control characteristics of the branch control valve due to variations in the operating range It is something that

In the present invention, the fixed throttle is connected in series with the variable throttle, so even if there is variation in the throttle opening with respect to the steering pressure, the degree of change as a composite throttle resistance in the branch flow path is reduced.
As shown in the figure, the amount of change in Δq becomes small, the variation in the flow rate control characteristics of the branch control valve becomes very small, and special adjusting means for determining the operating range of the variable throttle valve becomes unnecessary.

This eliminates the need for adjustment after assembly.

<Example> Embodiments of the present invention will be described below 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 pinion 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.
Rack teeth 22a of a rack shaft 22 that is slidable in a direction intersecting the pinion shaft 21 mesh with the pinion shaft 21. This rack shaft 22 is connected to the power cylinder 90 (see Fig. 3).
The piston is connected to the steering wheel, and both ends thereof are connected to the steering wheel via a required steering linkage mechanism.

A servo valve 30 is housed in 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 low-pressure 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.

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 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 port 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, both distribution ports 1
-33.34 is a low pressure and the pressure is equal, so the power cylinder 90 is not operated.

When the servo valve 30 deviates from the neutral state, pressure oil is supplied to one distribution hole 40 or 41 from the supply port 35,
Fluid discharged from the power cylinder 90 flows into the other distribution hole 41 or 40 and is discharged to the discharge port 36 via the communication passage 37, passage 39, and low pressure chamber 38.

The reaction force mechanism is as follows. At the end of the rotary valve member 31 on the pinion shaft 21 side, as shown in FIG. A fitting groove 51 is formed into which the part 50 is loosely fitted so as to be able to rotate at a slight angle about the axis of the input shaft 23.

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. This plunger 54 is projected forward by hydraulic pressure introduced into a reaction force chamber 55 formed behind it, and holds the protrusion 50 from both sides thereof, and its forward end is connected to the plunger 55.
It is regulated by a large diameter portion 54a formed in 4.

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 the 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.

In FIG. 3, 61 is a flow control valve that controls the flow rate QO of pressure oil discharged from the supply pump 60 driven by the automobile engine to a constant flow rate Qc. This flow control valve 6
1 includes a metering orifice 62 and a bypass valve 64 that is operated according to the front and rear pressure of the 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. In addition, when the supply pump 60 is a constant speed motor-driven type that discharges a constant flow rate, the flow rate control valve 6
1 is unnecessary.

Reference numeral 65 denotes a flow divider that is connected to the high pressure side of the flow rate control valve 61 via a supply passage 66 . This flow control valve 65 controls the flow rate QC to a control spool 67.
Accordingly, the flow is divided into a flow rate Qq to the passage 45 on the servo valve 30 side and a flow rate QR to the passage 46 on the reaction force chamber 55 side.

80 is a variable throttle valve. This throttle valve 80 has a passage 91
Gear generation pressure Pc introduced via the spring 82
The valve has a sliding spool 83 that slides based on the pressure balance with the repelling force of the valve, and a flow dividing restriction 84 is formed between the sliding spool 83 and the valve hole. This branching throttle 84 functions as a fixed throttle in the initial state, and then the gear generated pressure P. It functions as a variable aperture whose aperture area changes as the sliding spool 83 is displaced. A fixed throttle 85 is provided in series with this branch throttle 84 to control the flow rate of the pressure oil flowing through the branch passage 93. This branch passage 93 has one end connected to the supply passage 66 and the control spool 67 through a small hole 95 formed in the branch control valve 67.
The other end communicates with the front chamber 96 of the control spool 6.
It communicates with a rear chamber 99 of the branch control valve 65 through communication holes 97 and 98 formed in the valve 7 . Therefore, the throttle valve 8
By changing the aperture area of the 0 branch flow restrictor 84, the pressure balance between the front and rear chambers 95.99 of the branch flow control valve 65 changes, and the flow rate QC to the passage 45 on the servo valve 30 side and the flow rate QC on the reaction force chamber 56 side change. The ratio of the flow divided into the flow MQp to the passage 46 is changed. In addition, 69 is a spring for balance.

Further, an electromagnetic control valve 70 that is controlled according to vehicle speed and the like is inserted in the passage 46 on the side of the reaction force chamber 55.

As shown in FIG. 4, the electromagnetic control valve 70 consists of a valve body 7I, a spool 72 slidably fitted into the inner hole of the valve body 71, and a solenoid control circuit (surrounded by The solenoid 73 is supplied with a current (2) according to the vehicle speed signal (2) from the vehicle speed signal (4). The spool 72 is normally held at its lower end by a spring 74 and is connected to a diverter control valve 65 and a passageway 76 leading to the tank.
77 are communicated only through a small hole 78. When the solenoid 73 is energized, the spool 72 is displaced against the spring 74 according to the current value (2), and the passage 76.
77 are communicated through small holes 78 and slits 79.

In FIG. 3, 90 is a power cylinder, and 94 is a safety relief valve that releases pressure when the pressure inside the passage 46 exceeds a predetermined pressure.

Next, the operation of the above configuration will be explained. supply pump 60
A flow rate control valve 61 controls the flow lQo of the pressure oil discharged from the pump to a constant flow lQc. This pressurized oil controlled to a constant flow rate Qc is divided by the flow control valve 65 into flow rates Qa and QR toward the servo valve 30 side and the reaction force chamber 56 side, respectively, with the flow flow characteristics shown in FIG. . In the low speed state, as shown in FIG. 6, a large current I is supplied to the solenoid 73, which causes the spool 72 of the electromagnetic control valve 70 to largely displace, thereby fully opening the slit 79. Therefore passage 4
The pressure oil diverted to the 6 side is drained into the tank, and almost no reaction oil pressure PR is generated.

Therefore, when the input shaft 23 is rotated by operating the handle, the plunger 54 is easily pushed back, whereby the sleeve valve member 32 and the rotary valve member 31 are rotated relative to each other, and the change in the gear generation pressure pc with respect to the manual torque TM is The characteristics are shown by the low-speed, stationary curve in Figure 9, and the steering wheel can be operated easily.

When the vehicle speed increases thereafter, as shown in FIG. 6, the solenoid 73 of the electromagnetic control valve 70
The control current value ■ supplied to decreases. As a result, the spool 72 is displaced and the opening degree of the slit 79 becomes smaller.
As a result, the flow rate of the hydraulic pressure returned to the tank is restricted, and the reaction hydraulic pressure PR is increased. As the pressure oil pressure PR increases, the pressing force of the plunger 54 against the protrusion 50 increases, and the handle becomes heavier accordingly.

On the other hand, when the handle is operated, gear generation pressure pc is generated in the passage 45 leading to the servo valve 30 side.

This gear generated pressure PC causes the flow restriction 84 of the throttle valve 80 to
The diaphragm aperture area S gradually increases as shown in FIG.
When the sliding spool 83 reaches the stroke end, it becomes constant. As a result, the fluid flows into the diverter control valve 65 via the diverter restrictor 84 and fixed restrictor 85 of the throttle valve 80 . Since the dividing throttle 85 and the fixed throttle 85 are provided in series, the rate of change in the combined flow resistance is smaller than the rate of change of the dividing throttle 84 alone. As a result, the flow control valve 6
Changes in the pressure balance between the front and rear chambers 96 and 99 of No. 5 are also reduced, thereby reducing changes in flow rate characteristics of the flow dividing valve.

As shown in Fig. 5, as shown in Fig. 5, the shunt characteristics reduce the shunt restriction amount Q, and increase the shunt flow (t Q R) toward the reaction force chamber side, and this shunt flow ff
i Q Due to the increase in R, the reaction oil pressure PR becomes the gear generation pressure p
It rises according to c. As is clear from Fig. 8, this reaction oil pressure P9 rises only at a low rate at low speed and in the stationary state.
The gear generation pressure pc tends to increase rapidly as the speed increases, and the change characteristics of the gear generation pressure pc with respect to the manual torque TM are as shown in FIG. 9. In particular, since the configuration has a fixed throttle in series with the variable throttle, even if there is variation in the operating range of the variable throttle, the effect of the variation is absorbed by the fixed throttle, and at low speeds, the gear generation pressure pc relative to the manual torque TM is reduced. It is low, and at high speeds, it becomes heavier as you turn the steering wheel, giving you a responsive steering feel.

<Effects of the Invention> As detailed above, the device of the present invention supplies pressure oil supplied from the supply pump via the supply passage to the servo valve side, and branches a part of this pressure oil from the supply passage. A diversion control valve is provided that diverts the flow to the reaction chamber side via a branch passage, and a variable throttle whose opening degree is controlled by the gear generated pressure accompanying the steering of the servo valve is inserted in the branch passage of this diversion control valve. Since the fixed diaphragm is provided in series with the variable diaphragm, even if there is variation in the operating range due to the high spring constant of the variable diaphragm, this can be significantly reduced as a change in the shunt characteristics. This eliminates the need for special adjustment means for the operating range, making it possible to simplify the mechanism and facilitate assembly. Furthermore, when driving at high speeds, it is possible to reduce the slope of the characteristic of gear generation pressure relative to manual torque, thereby reducing power assist, which provides a responsive steering feel as you turn the steering wheel. It has the effect of

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a sectional view of the power steering device, FIG. 2 is a sectional view taken along line nn in FIG. 1, and FIG.
FIG. 3 is a hydraulic system diagram of the present invention, FIG. 4 is a sectional view of the electromagnetic control valve, FIG. 5 is a diagram showing the diversion characteristics of the diversion control valve, and FIG. 6 is a diagram showing the control characteristics of the electromagnetic control valve. Figure 7 is a diagram showing the control characteristics of the throttle valve, Figure 8 is a diagram showing the change characteristics of the reaction oil pressure, Figure 9 is a diagram showing the change characteristics of the gear generated pressure, and Figure 10 is a diagram showing the change characteristics of the fixed throttle valve. Figures 11 and 12 are diagrams showing the flow rate control characteristics when the valve is inserted into the valve, and Figures 11 and 12 show conventional devices. Figure 11 is a hydraulic system diagram, and Figure 12 is flow control due to variations in the valve body operating range X. It is a figure which shows the variable throttle area change of a valve. 21... Binion shaft, 23... Input shaft, 30...
Servo valve, 50... protrusion, 54... plunger,
55... Reaction force chamber, 65... Diversion control valve, 70...
Electromagnetic control valve, 80... Throttle valve, 84... Diversion throttle,
85...Variable aperture, 86...Fixed aperture.

Claims (1)

[Claims] (1) A servo valve that is operated based on the relative rotation between the input shaft and the output shaft to supply and discharge pressure oil to the power cylinder, a reaction force mechanism that changes the steering wheel torque according to vehicle speed, etc., and this reaction force mechanism In a steering force control device for a power steering device, which is equipped with an electromagnetic control valve that is installed on a passage leading to a pressure chamber and controls pressure oil generated in the reaction force chamber according to vehicle speed, etc., the supply passage is connected to a supply pump. A flow control valve is provided to supply pressure oil supplied through the servo valve side to the servo valve side and to divert a part of this pressure oil to the reaction force chamber side via a branch passage branching from the supply passage. A variable throttle whose opening degree is adjusted by gear-generated pressure associated with the steering of the servo valve is inserted in the branch passage of the branch control valve, and a fixed throttle is provided downstream of the variable throttle in series with the variable throttle. Steering force control device for power steering device.