JPS6053464A - Power steering device - Google Patents

Abstract

PURPOSE:To prevent an abrupt change of a steering force by controlling a hydraulic means so as to increase the torsional rigidity when the car speed is at a predetermined value or more and the steering angle is an angle outside a predetermined range in a power steering device having the hydraulic means changing the torsional rigidity of a torsion bar. CONSTITUTION:A piston 5 is inserted into a gap between an input shaft 1 receiving the input from a handle and a torsion bar 2 connected to the said shaft 1 via a pin 3. The piston 5 is moved to the left against a spring 9 via the oil pressure in a hydraulic chamber 8, and the torsional rigidity of the torsion bar 2 is made variable by changing the longitudinal position of a sleeve 14 spline- connected to the periphery of the torsion bar 2 via a connecting bar 15. In this case, a solenoid valve 18 is provided on an oil path branched from an oil passage 11 communicating to the hydraulic chamber 8, and the said valve 18 is controlled so as to increase the oil pressure in the hydraulic chamber 8 in response to outputs of a car speed sensor 20 and a steering angle sensor 21 when the car speed is at a predetermined value or more and the steering angle is an angle outside a predetermined range.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a power steering device, and more particularly to a power steering device in which the torsional rigidity of a torsion bar is changed to vary the steering force.

[Prior art]

Conventionally, the vehicle speed-sensitive type opens an electromagnetic pulp installed in the power cylinder in the power steering device when the vehicle speed reaches a predetermined speed or in proportion to the vehicle speed to lower the oil pressure in the power cylinder and increase the steering force. A power steering device is known. However, power steering increases the steering force when the vehicle speed reaches a predetermined speed.

In this device, since the steering force changes at a predetermined speed as shown in FIG. 1, there is a problem in that the steering feeling and smoothness are lacking. Also, in a power steering system that changes the steering force in proportion to the vehicle speed.

Since the steering force changes when the vehicle starts running, there is a problem in that it does not smoothly connect to the stationary steering force when the vehicle is stopped, resulting in a lack of smoothness, as shown in FIG. Furthermore, in the power steering system described above, the output is reduced because the steering angle is increased by lowering the oil pressure, and when the torque applied to the pitman arm is large as shown at point 0 in Figure @3, the steering force becomes heavy. For this reason, the third model, which is expected to increase the steering force,
There is a problem in that a sufficient effect cannot be obtained in the region below point b in the figure. The solid line in Figure 3 is the performance curve of a normal power steering system, the dashed-dotted line is the performance curve of a normal manual steering system, and the broken line is the performance curve of a conventional vehicle speed-sensitive power steering system that operates at a predetermined vehicle speed. This is a performance curve.

[Purpose of the invention]

The present invention has been made to solve the above-mentioned problems, and improves the steering feeling by smoothing the change in steering force, and also allows the performance curve of the power steering device to move smoothly when it is in operation and when it is not in operation. The purpose of the present invention is to provide a power steering device.

[Structure of the invention]

In order to achieve the above object, the present invention has a structure in which a tone bar is inserted into the input shaft and connected to the input shaft, and a tone bar is inserted between the input shaft and the torsion bar and is hydraulically operated in the axial direction of the torsion bar. A space formed by the inner surface of the input shaft, the outer surface of the torsion bar, and the side surface of the piston and communicated with the hydraulic pressure source.

A power steering device comprising: a sleeve connected to a piston and movably engaged with a torsion bar in response to oil pressure, and increasing torsional rigidity of the torsion bar as the oil pressure in the space increases. , which is equipped with a control device that increases the oil pressure in the space in proportion to the vehicle speed and steering angle when the vehicle speed is above a predetermined value and when the steering angle is outside a predetermined range centered on the direction in which the vehicle is traveling straight. be.

According to the configuration of the present invention, when the vehicle speed exceeds a predetermined value, the torsional rigidity is increased in proportion to the vehicle speed, and the steering force is increased. When the steering angle falls outside the predetermined range, the torsional rigidity is increased in proportion to the steering angle, and the steering force is increased. Further, when the vehicle speed exceeds a predetermined value and the steering angle falls outside the predetermined range, the steering force is increased not only in proportion to the vehicle speed but also in proportion to the steering angle.

〔Effect of the invention〕

According to the above configuration of the present invention, since the steering force is increased in proportion to the vehicle speed when the vehicle speed exceeds a predetermined value, the change in the steering force becomes smooth from when the vehicle is stopped to when the vehicle is running at high speed, and the steering angle is Since the steering force is changed accordingly, stability during turning is improved, and the torsional rigidity of the torsion bar is increased to change the aggregate reaction force (steering force).
The same effect can be obtained by lowering the oil pressure of the power cylinder, and the sufficient effect can be obtained in areas where an increase in steering force is expected.
A unique effect can be obtained.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 4 shows an embodiment of the present invention. This embodiment is configured to include a power steering device main body and a control device.

As shown in the partial sectional view of Fig. 4, the main body of the power steering device is
An input shaft 1 that receives input from the handle is connected to a torsion bar 2 inserted therein and a pin 3, and the torsion bar 2 is connected to an output shaft (not shown) by the same pin, so that the input shaft 1 is connected to an output shaft (not shown). It is configured to transmit torque to the output shaft. The ends of the input shaft 1 and the torsion bar 2 are sealed by a seal ring 4, and the inner circumference of the input shaft 1 and the torsion bar 2 are sealed at the axially inner side of the pin 3 (on the left side in Fig. 4). A gap is formed between the piston 5 and the outer circumference, and a piston 5 whose inner and outer circumferential sides are sealed with two seal rings 6 and 7 is provided within this gap so as to be movable in the axial direction. .

The piston 5 forms a hydraulic pressure space 8 on the right side of the drawing together with the inner periphery of the input shaft 1 and the outer periphery of the torsion bar 2, and on the opposite side there is a spring 9 and a reservoir for locking the spring 9. A stopper ring 10 is provided.

In addition, an oil passage 11 is formed in the center of the torsion bar 2, and this oil passage 11 communicates the space 8 with a hydraulic pump 13 driven by a transmission 12, and the transmission 12 drives the hydraulic pump 13. By doing so, hydraulic pressure is supplied from the hydraulic pump 13 into the space 8 to move the piston 5 in the axial direction against the biasing force of the spring 9.

On the other hand, the piston 5 is connected to a sleeve 14 spline-coupled to the inner peripheral surface of the input shaft 1 and the outer peripheral surface of the torsion bar 2.
are connected to each other by a connecting bar 15.

Therefore, as the piston 5 is moved in the axial direction by the hydraulic pressure from the hydraulic pump 13, the sleeve 14 is moved against the piston 5.
It will also move in the axial direction.

In this case, the force with which the sleeve restrains the torsion bar 2 changes depending on the axial position of the sleeve 14, and the torsional rigidity of the torsion bar 2 changes accordingly.

That is, when the oil pressure is low and the sleeve 14 is in the right position in the figure, the torsional rigidity of the torsion bar 2 is reduced and steering can be performed with a small steering force.
When the sleeve 14 moves one step to the left in the figure, the torsional rigidity of the torsion joint 2 increases, and a large steering force is required during steering.

The control device includes an electromagnetic solenoid 18 that controls the opening degree of the spool valve 17 and a control circuit 19. The control circuit 19 includes a vehicle speed sensor 20 that detects vehicle speed by driving a reed switch and a magnetically sensitive element using a big amplifier fixed to the speedometer cable, and a variable resistor attached to the steering shaft. A steering angle sensor 21 is connected to detect the steering angle from changes.

The control circuit 19 includes a diode D whose cathode is connected to a reed switch of the vehicle speed sensor 20, as shown in FIG.
It is equipped with The anode of diode D is connected to the input end of frequency-voltage converter 22 via resistor R7. The input terminal of the frequency-voltage converter 22 is connected to the vehicle-mounted batch +7B via a resistor R2, and is also grounded via a capacitor CI. The output terminal of the frequency-voltage converter 22 is connected to a non-inverting terminal of an operational amplifier OP constituting a comparator 24. A resistor R8 is connected to the inverting terminal of the operational amplifier OP. A reference voltage corresponding to a predetermined vehicle speed (for example, 60 Km/b) is applied. The output terminal of the operational amplifier OP is a transistor Tr of a duty ratio control circuit 3° that controls the duty ratio of the resistor R3 of the adder 26 and the electromagnetic solenoid.
connected to the base of.

The adder 26 is composed of a resistor R2 and an operational amplifier OP2, and the output end of the adder 26 is connected to an inverting circuit 28 composed of a resistor R+8%J and an operational amplifier OP3. This inversion circuit 28 is connected to a duty ratio control circuit 30.

The duty ratio control circuit 30 includes a comparator equipped with an operational amplifier OP4, a duty ratio control comparator equipped with an operational amplifier OP, and transistors 'J' r, l Tr2, T.
It is comprised of a switching circuit equipped with r3, an oscillator 32 that outputs a triangular wave signal of a predetermined frequency, and a current detection circuit 34 that detects the excitation current flowing through the current solenoid 18. This current detection circuit 34 is composed of an operational amplifier OP6, a resistor R1 (1"I"+4), and a capacitor C2. The output terminal of the operational amplifier OP4 is connected to the inverting terminal of the operational amplifier OP via a resistor R8. The oscillator 32 is also connected to the inverting terminal of the operational amplifier OP4 and the resistor via the resistor RI6.
5 and 7 to the non-inverting terminal of the operational amplifier OP.

The output end of the operational amplifier OP is connected to the base of the transistor Tr via a resistor R8. The collector of the transistor Tr is connected to the battery B via the resistor R, , and the emitter of the transistor Tr is connected to the battery B.
It is connected to the. The emitter of the transistor Tr1 is
It is connected to the base of the transistor IJIr and the emitter of the transistor Tr3. Transistor T'
The collectors of r, Tr3 are grounded via a diode D, and are connected to one end of the electromagnetic solenoid 18. In an electromagnetic solenoid, there is a wire between the emitter and collector of the transistor Tr.

Iode D is connected.

The midpoint of the variable resistor constituting the steering angle sensor 21 is connected to the adder 26 via a comparator 34 and an inversion circuit 32. The comparator 34 includes an operational amplifier OP, a resistor OP,
1, J2, R, , s, and the steering angle is within a predetermined range (for example, ±9
When the steering angle reaches an angle other than 0°, a signal corresponding to the steering angle is output. Further, the inverting circuit 32 includes an obedenbu OP8 and resistors R74 and R2.

The operation of this embodiment will be explained below. In addition, in the following, the predetermined value of the vehicle speed is 60 Km/l+, and the range of the steering angle is ±90.
Describe as °. A pulse signal corresponding to the vehicle speed output from the vehicle speed sensor 20 is converted into a voltage signal (2) shown in FIG. 6(1) by the frequency-voltage converter 22 and output. This voltage signal ■1 is applied to the comparator 24 at a vehicle speed of 6.
It is compared with the reference voltage for 0 Km/Ii, and
) is output as the voltage signal ■.

On the other hand, the voltage corresponding to the steering angle detected by the steering angle sensor 21 is processed by the comparator 34 and the inverting circuit 32 and outputted as a voltage signal 2 shown in FIG. 6(3).

The above voltage signal ■2 and voltage signal v3 are sent to the adder 26
After addition, the result is inverted by the inverting circuit 28, and the result is shown in FIG. 6 (4).
It is output as the voltage signal ■4 shown in .

Note that the line A in FIG. 6(4) is the voltage signal ■4 when the steering angle is O to ±90°, that is, when the voltage signal V8 is O and the voltage signal ■2 is in the state of FIG. 6(2). The line B shows the voltage signal 4 when the steering angle is at the maximum and the voltage signal 2 is in the state shown in FIG. 6(2).

Next, the operation of the duty ratio control circuit 30 will be explained with reference to FIG. The current (2) flowing through the electromagnetic solenoid 18 is rectified and amplified by the current detection circuit, and is inputted to the operational amplifier OP4 as a reference signal (2), and is compared with the voltage signal (2) mentioned above and inputted to the operational amplifier OP as a voltage signal V6. Operational amplifier OP.

Since the triangular wave signal (7) from the triangular wave oscillator 32 is input to the circuit, the voltage signal (6) is compared with the triangular wave signal (7), and the comparison result is input to the transistor Tr as a control signal (4).

On the other hand, when the voltage signal (2) rises, the transistor Tr is turned on, and the on/off of the transistor Tr2 controls the on/off of the transistor Tr, and the duty ratio of the electromagnetic solenoid is controlled by the on/off of the transistor 1r.

As a result of the above, the steering angle θn] is in the straight direction of the vehicle (θm=0)
When the steering angle θm becomes 1908 or more, the duty ratio for controlling the electromagnetic solenoid is increased in accordance with the steering angle θm, and the opening degree of the spool pulp 17 is decreased in accordance with the steering angle, as shown in FIG.

Therefore, the oil pressure in the space 8 is increased, and as shown in FIG. 8, the torque Tm applied to the steering wheel is increased in accordance with the steering angle, and a large steering force is required. Further, when the vehicle speed (2) exceeds 60 km/h, the duty ratio for controlling the electromagnetic solenoid is increased in accordance with the vehicle speed V, and the opening degree of the spool valve 17 is decreased in accordance with the vehicle speed, as shown in FIG. For this reason, the oil pressure in the space 8 is increased, and as shown in FIG. 9, the torque Tm applied to the steering wheel is increased in accordance with the vehicle speed, and a large steering force is required. Note that when the vehicle speed V is 60 KJn/'h or more and the steering angle θm is 1908 or more, the torque Tm is increased according to the vehicle speed and the steering angle.

FIG. 10 shows the same performance curve as FIG. 3 in this example. According to this embodiment, the torsional rigidity of the torsion bar is increased to change the steering force, so there is a drawback to the method of increasing the steering force by lowering the hydraulic pressure of the power cylinder (if the torque applied to the pitman arm is large, the steering force will be increased). However, this problem can be solved (particularly in areas where an increase in steering force is expected, a sufficient effect cannot be obtained).

[Brief explanation of drawings]

Figs. 1 and 2 are conventional diagrams showing the relationship between vehicle speed and torque Tm, Fig. 3 is a diagram showing a conventional performance curve, and Fig. 4 is a schematic waveform showing an embodiment of the present invention. Figure 8 shows the steering angle θm, spool valve opening and torque T.
FIG. 9 is a diagram showing the relationship between vehicle speed ■, spool pulp opening and torque Tm, and FIG. 10 is a diagram showing the performance curve of this embodiment. DESCRIPTION OF SYMBOLS 1... Input shaft, 2... Torsion bar, 5... Piston, 8... Space, 14... Sleeve, 17... Spool pulp, 18... Electromagnetic solenoid, 19... Control circuit, 20...Vehicle speed sensor, 21...Steering angle sensor. Agent Tatsuyuki Unuma (and 1 other person) Figure 1 @ 2 Figure 3 Figure 4 12 Figure 7 ゛'''Skin, Tiger Hi====== Figure 8 Figure 9

Claims (1)

[Claims] (1) A torsion bar that is inserted through the input shaft and connected to the input shaft; and a torsion bar that is interposed between the input shaft and the torsion bar and that can be moved in the axial direction by hydraulic pressure. a space formed by an inner surface of the input shaft, an outer surface of the torsion bar, and a side surface of the piston and communicated with a hydraulic pressure generation source; and a torsion bar connected to the piston and movable according to the hydraulic pressure. A power steering device comprising: a sleeve that increases the screw rigidity of the torsion bar as the hydraulic pressure in the space increases;
a vehicle speed sensor that detects vehicle speed; a steering angle sensor that detects steering angle; and a vehicle speed sensor that detects vehicle speed and a steering angle sensor that detects steering angle. A power steering device comprising: a control device that increases hydraulic pressure in the space in proportion to the steering angle.