JPH07165093A - Power steering device for automobile - Google Patents

Abstract

PURPOSE:To dispense with a member for dividing the oil pressure in response to the steering direction of a steering wheel and a sensor member for detecting the steering torque, and to obtain the assist force for steering. CONSTITUTION:As a driving source of a valve driving actuator 15 for generating the separate torsion moment in a torsion bar 9, oil pressure to be output from a rotary valve 16 at the time of steering a steering wheel 13 is used, and the assist force is obtained by the oil pressure generated in response to the steering torque of the steering wheel 13, and the control of the oil pressure on the basis of the steering torque is eliminated to eliminate a member for dividing the oil pressure is response to the steering direction of the steering wheel and a sensor member for detecting the steering torque.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle steering system used for steering front wheels of a vehicle.

[0002]

2. Description of the Related Art Some automobiles are equipped with a hydraulic power steering device so that steering can be performed by a driver's light steering operation. In this power steering device, an input shaft connected to a steering wheel and an output shaft connected to a steered wheel (front wheel) are connected by a torsion bar, and a rotational force of the input shaft is transmitted as a steering force of the front wheel by interposing a hydraulic assist system. I am trying.

A conventional power steering system will be described with reference to FIG. FIG. 22 shows a schematic configuration of a conventional power steering device.

In the figure, reference numeral 2 is a rack and pinion type steering gear which constitutes the steering mechanism 1, and the steering gear 2 has a structure in which a rack 4 and a pinion 5 are incorporated in a casing 3. One end of the rack 4 has a steering rod 6 and a tie rod 6a.
And one of the front wheels 8 via a knuckle 6b. The other end of the rack 4 is connected to the other front wheel 8 via a steering rod 6, a power cylinder device (cylinder mechanism) 7, a tie rod 6a and a knuckle 6b.

A lower end of a torsion bar 9 is connected to the pinion 5 of the steering gear 2 via an output shaft 5a (output shaft). The upper end of the torsion bar 9 penetrates the valve unit 10 provided on the upper portion of the steering gear 2 and is connected to the input shaft 11 (input shaft). Also input shaft 11
The end of is connected to the handlebar 13 via the steering shaft 12. When the rotational displacement is input from the handle 13, the steering shaft 12, the torsion bar 9, the pinion 5, the rack 4, and the steering rod 6
The left and right front wheels 8 are steered via the.

The valve unit 10 includes a housing 1 on the top of the steering gear 2 so as to surround the torsion bar 9.
4 is installed, and a valve drive actuator 15 (valve drive mechanism) and a rotary valve 16 are provided in a portion from the upper portion of the steering gear 2 to the inside of the housing 14.
Are provided in order from the lower side. Rotary valve 16
Has a cylindrical outer valve rotatably provided on the inner surface of the housing 14, and a cylindrical inner valve that is combined with the outer valve integrally provided on the input shaft 11. That is, the rotary valve 16 has the handle 1
When the torsion bar 9 is twisted by the rotation operation from 3, the relative displacement is generated between the outer valve and the inner valve. Rotary valve 16
Is provided with an inflow port body 19, an outflow port body 20, and a pair of output port portions 21 and 22, and the output port portions 21 and 22 are connected to the power cylinder device 7.

As shown in the figure, in the power cylinder device 7, a piston rod 24 is slidably provided in the cylinder 23 so as to penetrate the cylinder 23, and the cylinder 23 is longitudinally attached to a part of the piston rod 24. A piston 25 is provided so as to be partitioned on both sides (left and right). A pair of input ports 26, 27 communicating with the left and right chambers 25a, 25b partitioned by the piston 25 are connected to the output port portions 21, 22 via the flow paths 28, 29.

The inflow port body 19 of the rotary valve 16 includes a flow path 30 and a flow dividing unit 31 (one of the inlet ports 31a and 2).
One outlet 31b, 31b is a flow path 31 with an orifice
(c, 31c are connected), and is connected to an oil pump 33 (hydraulic pressure generating portion) with a relief valve driven by a running engine 32 of the automobile. The outlet body 20 of the housing 3 is connected to the oil reservoir 35 via the flow path 34, and a hydraulic circuit for the power cylinder device 7 is configured.

When the outer valve and the inner valve of the rotary valve 16 are relatively displaced, the hydraulic circuit supplies hydraulic pressure corresponding to the steering force and the steering direction from the rotary valve 16 to the chambers 25a and 25b of the power cylinder device 7. It That is, the front wheels 8 are steered while being hydraulically assisted.

The valve drive actuator 15 comprises an overhanging portion 42 provided on the input shaft 11 and plungers 44a, 44b for pressing the overhanging portion 42 in the circumferential direction of the input shaft 11 to rotate the plungers 44a, 44b. The overhanging portions 42 are pressed in opposite directions. Valve drive actuator 1
5 is provided with a first inlet / outlet body 54 and a second inlet / outlet body 55, the first inlet / outlet body 54 is connected to a hydraulic chamber for driving the plunger 44a, and the second inlet / outlet body 55 is connected to the plunger 44b.
Is connected to the hydraulic chamber that drives.

First inlet / outlet body 54 and second inlet / outlet body 55
Are the flow paths 56 and 57, the first and second control valves 58 and 59, which are pressure adjusting valves, and the diversion unit 60, respectively.
(One inlet part 60a and two outlet parts 60b, 60b are connected by flow paths 60c, 60c with an orifice) are connected to the other outlet part 31b of the flow dividing unit 31, By operating the first and second control valves 58 and 59, the oil pressure from the oil pump 33 divided by the flow dividing units 31 and 60 is changed to the inlet / outlet body 54 or the inlet / outlet body 5.
5 are supplied. Incidentally, each control valve 58,
The return portion 59 is connected to the oil reservoir 35 by the flow path 34.

In the hydraulic circuit 64 configured as described above, when only the first control valve 58 is operated, the pressure oil from the oil pump 33 drives the plunger 44a via the first inlet / outlet body 54. Supplied to the hydraulic chamber. As a result, the plunger 44a presses the overhanging portion 42, and causes the torsion bar 9 to generate, for example, a torsion moment in the forward rotation direction (right direction) of the rotary valve 16. Further, when only the second control valve 59 is operated, the pressure oil from the oil pump 33 is supplied to the hydraulic chamber that drives the plunger 44b via the second inlet / outlet body 55. As a result, the plunger 44b presses the overhanging portion 42 and causes the torsion bar 9 to generate a torsion moment in the reverse direction (left direction) of the rotary valve 16, for example. Therefore, the torsional moment can be independently generated in the torsion bar 9 by the switching movement of the first and second control valves 58, 59.

A control unit (ECU) 70 is connected to the solenoid portions 58a and 59a of the first and second control valves 58 and 59 as a control means composed of a microcomputer and its peripheral circuits. ECU
Reference numeral 70 denotes a vehicle speed sensor 71 for detecting a traveling speed (vehicle speed) of the automobile, a steering wheel angle sensor 72 for detecting a steering angle (steering wheel angle) of the steering wheel 13, and a torque sensor 73 for detecting a torque (steering torque) acting on the steering wheel 13. Are connected.

With this control system, the range of the target assist force is set by the assist force obtained by rotating the rotary valve 16 in the same direction as the torsional direction of the torsion bar 9, and the plunger 44a is set to this assist force. , 44b are driven to generate the required torsional moment in the torsion bar 9.

In the power steering system described above, when the torsion bar 9 is twisted when the steering wheel 13 is steered, hydraulic pressure corresponding to the steering force and the steering direction is supplied from the rotary valve 16 to the power cylinder system 7, and the front wheels are hydraulically operated. It is steered while being assisted. Further, depending on the vehicle speed, the steering wheel angle and the steering torque, the first and second control valves 5
8, 59 are actuated to independently generate a torsional moment in the torsion bar 9 to obtain a target assist force according to the traveling situation. As a result, the burden of steering wheel operation can be reduced under a wide range of steering conditions.

[0016]

In the conventional power steering system, the pressure oil from the oil pump 33 is supplied to the control valve 5.
Since it is sent to the valve drive actuator 15 via 8 and 59, hydraulic pressure of a predetermined pressure is sent to the control valves 58 and 59 regardless of the steering torque. For this reason,
The control valves 58 and 59 are operated according to the steering torque detected by the torque sensor 73. As a result, the valve drive actuator 15 is supplied with hydraulic pressure according to the steering torque. Therefore, the conventional power steering device requires the flow dividing unit 31 and the torque sensor 73 to reflect the steering torque in the assist force, which increases the number of parts and complicates the control. Also,
Since the pressure oil from the pump 33 is divided by the flow dividing unit 31 and supplied to the valve drive actuator 15, when the control valves are provided according to the steering direction, the flow dividing unit 60 is further required and the number of parts is further increased. Resulting in.
Further, when the control valves 58, 59 fail in the ON state, the independent hydraulic pressure by the flow dividing unit 31 acts on the valve drive actuator 15, so that the steering wheel 13 is operated even when the vehicle is moving straight.
However, there is a problem in that the system becomes complicated because it requires a fail-safe function, judgment, etc.

The present invention has been made in view of the above situation, and the steering torque can be reflected in the assist force without increasing the number of parts, and the control is performed only when the steering wheel is steered, which is advantageous in terms of fail-safe. An object of the present invention is to provide a power steering device having the above.

[0018]

The structure of the present invention for achieving the above object is rotatably supported coaxially in a housing and connected to each other through a torsion bar so as to be rotatable relative to each other. A steering mechanism that has an input shaft connected to the steering wheel side and an output shaft connected to the steered wheel side, and that steers the steered wheel according to a steering operation of the steering wheel; a hydraulic pressure generation unit that generates a predetermined hydraulic pressure; Valve means provided between the input shaft and the output shaft of the steering mechanism and connected to the hydraulic pressure generating portion to relatively displace the hydraulic pressure according to the torsion of the torsion bar during the steering operation of the steering wheel and output the hydraulic pressure; , Having left and right chambers, and the hydraulic pressure from the valve means acts on one of the left and right chambers in accordance with the steering operation of the steering wheel to drive the steered wheels in the steering direction. A cylinder mechanism and a pressed portion provided on at least one of the input shaft or the output shaft so as to project in the radial direction of the shaft, and is connected to the left and right chambers of the cylinder mechanism and acts on the left and right chambers. There is a pressing element provided on at least the other side of the input shaft or the output shaft so as to be able to press the pressed portion in the circumferential direction of the shaft by driving hydraulic pressure, and the pressed portion driven by the pressing element. A solenoid valve is provided between the cylinder drive and the valve drive means for generating an independent twisting moment in the torsion bar by pressing the solenoid bar, and the hydraulic pressure acting on the pusher by exciting the solenoid valve is controlled. The pusher driving means to be controlled and the target assist force of the assist force obtained by rotating the valve means in the same direction as the torsion direction of the torsion bar are set, and the handle is set. To the driving the pressing elements of the valve mechanism so that the target assist force during a steering operation, characterized by comprising a control means for excitation of the solenoid valve.

[0019]

When the steering wheel is steered, the torsion bar, which is about to be twisted by a difference from the road surface resistance, is twisted in a predetermined direction by the valve drive mechanism so that the target assist force is obtained. As a result, the rotary valve is initially driven by the valve drive mechanism, and then the rotary valve is driven by the torsion bar that is twisted by the difference with the road surface resistance, and the necessary hydraulic pressure is supplied to the cylinder mechanism.

The steering force obtained at this time is the steering force of the cylinder mechanism due to the output of the rotary valve in the region of the operating angle of the torsion bar twisted by the steering wheel operation, and the driving force of the pusher of the valve drive mechanism due to the output of the rotary valve. Changes in a region combined with the steering force generated by rotating the rotary valve in the torsional direction of the torsion bar. The steering force is assisted by the operation of the cylinder mechanism and the valve drive mechanism by the output of the rotary valve according to the steering torque of the steering wheel.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration of a power steering apparatus according to a first embodiment of the present invention, FIG. 2 is a cross section showing a steering mechanism, FIG. 3 is a view taken along the line III-III in FIG.
Shows the IV-IV line arrow in FIG. The same members as those shown in FIG. 23 are designated by the same reference numerals, and duplicate explanations are omitted.

As shown in FIG. 1, the flow passages 28 and 29 connecting the output ports 21 and 22 of the rotary valve 16 and the input ports 26 and 27 of the power cylinder device 7 are branched to form the first passage of the valve drive actuator 15. , And the flow paths 101 and 102 for connecting the second inlet / outlet bodies 54 and 55 are provided. First and second control valves 103 and 104 as electromagnetic valves are provided in the flow paths 101 and 102, and the steering torque output from the rotary valve 16 by the operation of the first and second control valves 103 and 104. The hydraulic pressure corresponding to is supplied to the first and second inlet / outlet bodies 54 and 55.
The return portions of the control valves 103 and 104 are connected to the flow path 34 and to the oil reservoir 35.

The steering mechanism will be described with reference to FIGS. 2 to 4.

In the rotary valve 16, a cylindrical outer valve 17 is rotatably provided on the inner surface of the housing 14, and a cylindrical inner valve 18 that is combined with the outer valve 17 is integrally provided on the input shaft 11. That is, the rotary valve 16 is configured such that when the torsion bar 9 is twisted by the rotation operation from the handle 13, a relative displacement is generated between the outer valve 17 and the inner valve 18.

The inflow port 17a formed in the outer valve 17 is an inflow port body 19 provided in the housing 3.
The outflow port 18a formed in the inner valve 18 communicates with the outflow port body 20 provided in the housing 3. An output port (not shown) formed in the outer valve 17 communicates with a pair of output port portions 21 and 22 provided in the housing 3. The output port units 21 and 22 are connected to the power cylinder device 7.

Outer valve 17 of rotary valve 16
When the inner valve 18 and the inner valve 18 are displaced relative to each other, hydraulic pressure corresponding to the steering force and the steering direction is applied from the rotary valve 16 to the chambers 25a, 2 of the power cylinder device 7 by the hydraulic circuit.
5b. That is, the front wheels 8 are steered while being hydraulically assisted.

The valve drive actuator 15 will be described.

An extension portion 37 is formed at a lower end portion of the input shaft 11 (a shaft portion immediately below the inner valve 18). The extension portion 37 is formed such that the lower end portion of the input shaft 11 is downward along the axial direction of the torsion bar 9. Has been extended to. The casing 3 around the extension portion 37 has a large diameter portion, and a circular chamber 4 is formed in the large diameter portion.
7 are formed. Inside the chamber 47, a hollow circular large-diameter portion 38 integrally connected to the output shaft 5a is rotatably accommodated. The large diameter portion 38 is connected to the outer valve 17 of the rotary valve 16 via a pin 36. An inner sleeve 39 is fitted over the entire outer peripheral surface of the large-diameter portion 38, and the outer sleeve 4 is attached to the inner peripheral surface of the chamber 47 facing the inner sleeve 39.
0 is rotatably fitted.

As shown in FIGS. 3 and 4, inside the large-diameter portion 38, radii are obtained from two symmetric points 180 degrees apart in the through-hole 38a of the large-diameter portion 38 in the circumferential direction. A flat concave-shaped chamber 41 extending outward in the direction is formed.

The extended portion 37 covered with the large diameter portion 38 has
Plate-shaped projecting portions 42 (pressed portions) that project outward in the radial direction from two symmetrical points that are separated by 180 degrees in the circumferential direction are formed. Each of the overhanging portions 42 is formed to have an outer shape smaller than the length and width dimensions of the chamber 41, and the overhanging portions 42 are concentrically loosely fitted in the chamber 41. The gap between the plate-shaped overhanging portion 42 and the flat chamber 41 is set to a size that can set the region necessary to compensate the operating angle of the rotary valve 16, and the torsion bar 9 is set at a predetermined angle with respect to the input shaft 11. It is designed to be twisted within a range.

Holes, for example, four circular hole portions 43 are symmetrically formed on both sides of the large diameter portion 38 across the chamber 41 so as to be continuous in series with the overhanging portion 42 interposed therebetween. . Plungers 44a and 44b (pressers) are axially slidably fitted in the holes 43, respectively. A protrusion 42a is formed at the center of the tip of each plunger 44a, 44b, and the plate surface portion of the overhanging portion 42 is pressed by the protrusion 42a. Further, the total length of each plunger 44a, 44b is set shorter than the length dimension of the hole 43, and the hydraulic chambers 45, 46 are formed in the hole surrounded by the rear end surface of the plunger 44a, 44b and the inner sleeve 39, respectively. Has been formed. Hereinafter, of these four symmetrical hydraulic chambers 45, 46, the two on the rear side in the clockwise direction with respect to the chamber 41 will be referred to as the first hydraulic chamber 45 and the chamber 4
The two on the front side in the clockwise direction with respect to the first hydraulic chamber 46
Enter.

As shown in FIG. 2, the inner sleeve 39
A first annular oil passage 48 is provided on the outer peripheral surface of the inner sleeve 39, and a second annular oil passage 49 is provided on the lower outer peripheral surface of the inner sleeve 39.
Is provided. As shown in FIG. 3, the first annular oil passage 48 is connected to the two first oil pressure chambers 45 via the first hole passages 50a provided in the inner sleeve 39 corresponding to the positions of the respective first oil pressure chambers 45. It is in communication. Further, as shown in FIG. 4, the second annular oil passage 49 is connected to the two second oil pressure chambers 46 via the second hole passages 50b provided in the inner sleeve 39 corresponding to the positions of the respective second oil pressure chambers 46. It is in communication.

As shown in FIG. 2, the outer sleeve 40
A first annular oil passage 51 is provided on the outer peripheral surface of the outer sleeve 40, and a second annular oil passage 52 is provided on the lower portion of the outer peripheral surface of the outer sleeve 40.
Is provided. Reference numeral 53 in the drawing denotes the upper stage of the first annular oil passage 51, the first annular oil passage 51 and the second annular oil passage 5
It is an O-ring for oil passage sealing that is provided between the second annular oil passage 52 and the second annular oil passage 52.

As shown in FIG. 3, the outer sleeve 40
The first annular oil passage 51 of the first
The second annular oil passage 52 of the outer sleeve 40 communicates with the inlet / outlet body 54, and the second inlet / outlet body 5 is formed in the casing 3.
It communicates with 5.

The first annular oil passage 48 of the inner sleeve 39
The first annular oil passage 51 of the outer sleeve 40 communicates with each other through first communication holes 61, 61 provided in the outer sleeve 40. Further, the second annular oil passage 49 of the inner sleeve 39 and the second annular oil passage 52 of the outer sleeve 40 communicate with each other through the second communication holes 62, 62 provided in the outer sleeve 40.

The hydraulic circuit 105 configured as described above
First and second control valves 10 (presser driving means)
The situation of the operation of 3, 104 and the action of the hydraulic pressure on the first and second hydraulic chambers 45, 46 will be described with reference to FIGS. 5A and 5B, the first and second hydraulic chambers 45,
The state of action of hydraulic pressure on the valve 46 is shown in FIGS. 6 (a) and 6 (b).
The operation of the plungers 44a and 44b corresponding to is schematically shown.

As the first and second control valves 103 and 104, control valves are used in which the pressure sent to the flow paths 101 and 102 decreases as the control voltage increases. When the control voltage of the set value is applied to the first and second control valves 103 and 104 (non-operation), the hydraulic pressure does not act on the first hydraulic chamber 45 and the second hydraulic chamber 46.

When only the first control valve 103 is operated, as shown in FIGS. 5 (a) and 6 (a), the rotary valve 1
The pressure oil output from 6 is supplied to the first hydraulic chamber 45, the plunger 44a presses the overhanging portion 42, and the torsion bar 9 causes, for example, the normal rotation direction (right direction) of the rotary valve 16.
The twisting moment of is generated. That is, the valve operating angle of the rotary valve 16 is slightly increased.

When only the second control valve 104 is activated,
As shown in FIGS. 5B and 6B, the pressure oil output from the rotary valve 16 is supplied to the second hydraulic chamber 46,
The plunger 44b presses the overhanging portion 42 to generate a torsion moment in the torsion bar 9 in the reverse rotation direction (left direction) of the rotary valve 16, for example.

When the first and second control valves 103 and 104 are inactive, the pressure oil output from the rotary valve 16 is not supplied to the first hydraulic chamber 45 and the second hydraulic chamber 46,
The plungers 44a and 44b do not press the overhanging portion 42,
The torsion bar 9 does not generate a twisting moment.
Therefore, the rigidity of the torsion bar 9 can be increased.

A control unit (ECU) 70 is connected to the solenoid portions 103a and 104a of the first and second control valves 103 and 104 as a control means composed of a microcomputer and its peripheral circuits. The ECU 70 indicates the traveling speed of the vehicle (vehicle speed: Vel).
And a steering wheel angle sensor 72 for detecting the steering angle (steering wheel angle: θh) of the steering wheel 13
Are connected. With this control system, the target assist force range is set by the assist force obtained by rotating the rotary valve 16 in the same direction as the torsion direction of the torsion bar 9, and the plungers 44a and 44b are set so as to have this assist force. The torsion bar 9 is driven to generate a required twisting moment.

Therefore, the ECU 70 is connected with a function of determining whether the handle 13 is operated in the forward (right) or reverse (left) direction, and a function of obtaining a target torque required for operating the handle 13 at this time. ing. Further, the function of calculating the control voltage value of the solenoids 103a and 104a, the function of determining the current variation of the steering wheel angle θh of the steering wheel 13 (steering wheel angular velocity θhs), and the first and second control valves 1
A function for operating 03 and 104 according to the above calculation result is set.

Next, the control operation in the ECU 70 will be specifically described with reference to FIGS. 7 to 11.

The ECU 70 is started by the ON signal of the ignition key switch (IG). Step S1
Initialization is performed, each control flag is set to 0 (non-execution side), and all variables are set to 0. Further, various coefficients are set to preset values.

The neutral signal (Hc value) of the steering wheel 13 is read in step S2, and the steering wheel angle θh detected by the steering wheel angle sensor 72 is read in step S3. Then, in steps S4 and S5, the vehicle speed Vel and the steering wheel angular velocity θhs detected by the vehicle speed sensor 72 are read. The steering wheel angular velocity θhs is read based on the map shown in FIG. That is, in order to perform the advance control for advancing the phase of the steering wheel angle θh with respect to the steering force, the advance coefficient Kh-V of the relationship shown in FIG. 12 is set with respect to the vehicle speed Vel, and the steering wheel is calculated based on this map. The angular velocity θhs is controlled.

After the neutral signal (Hc value) of the steering wheel 13, the steering wheel angle θh, the vehicle speed Vel and the steering wheel angular velocity θhs are read, the steering force setting routine of step S6 is executed to set the steering force according to the steering situation. It The steering force setting routine will be described with reference to FIG.

As shown in FIG. 8, in step S7, a steering force total coefficient (coefficient) KK is calculated based on the assist control coefficient KV1, the phase advance coefficient Kh-V, and the steering wheel angular velocity θhs. That is, KK = 50KV1 + Kh−V · | θhs |
The coefficient KK is calculated by / 5. The assist control coefficient KV1 is set to the relationship shown in FIG. 13 with the vehicle speed Vel.

After the coefficient KK is calculated in step S7,
In step S8, it is determined whether the steering wheel angle θh is 10 deg or more. When it is determined that the steering wheel angle θh is 10 deg or more, the direction determination routine Tq-OUT in step S9.
Proceed to 1 and execute right-turn assist control. Steering wheel angle θ
If it is determined that h is less than 10 deg, step S
Then, the routine proceeds to step 10, where it is determined whether the steering wheel angle θh is −10 deg or less. When it is determined that the steering wheel angle θh is −10 deg or less, the direction determination routine Tq-OU in step S11.
Proceed to T2 to execute left-turn assist control. When it is determined that the steering wheel angle θh exceeds −10 deg, it is determined in step S12 whether or not the absolute value | θh | of the steering wheel angle is less than 10 deg. Absolute value of steering wheel angle ｜ θ
If h | is determined to be less than 10 deg, the process proceeds to the direction determining routine Tq-OUT0 in step S13, the control is performed when the steering wheel is neutral, and the absolute value of the steering wheel angle | θh |
When is determined to be 10 deg or more, the process returns to the main flowchart.

The direction determining routine Tq-OUT1 in step S9 will be described with reference to FIG.

As shown in FIG. 9, 4.5 in step S14.
The command control voltage Vol is set to a value obtained by subtracting the absolute value | KK | of the coefficient from V. In step S15, the command control voltage Vo
It is determined whether or not l is less than 2.5V, and if it is less than 2.5V, the command control voltage Vol is set to 2.5V (lower limit value setting) in step S16, the process proceeds to step S17, and 2.5V is set. In the above case, the process directly proceeds to step S17. In step S17, the assist control flag Volflg is set to 1 (right-turn assist).

In step S18, the command control voltage Vol is output to the solenoid portion 103a of the first control valve 103, and 4.5V is output to the solenoid portion 104a of the second control valve 104. That is, as shown by the solid line in FIG. 14, the command control voltage Vol corresponding to the vehicle speed Vel is output to the first control valve 103, the hydraulic pressure is generated according to the command control voltage Vol, and the assist force in the right-turn direction is generated. It is generated (FIG. 14 (a)). The second control valve 104 has 4.
5V is output so that the hydraulic pressure is not generated and the assisting force in the left-turn direction is not generated (FIG. 14 (b)). The command control voltage Vol is, as shown in FIG. 16, a vehicle speed Vel.
It is set for each handle angle θh.

The direction determining routine Tq-OUT2 in step S11 will be described with reference to FIG.

As shown in FIG. 10, steps S19 and S
20 and S21, the command control voltage Vol is calculated in the same manner as described above, and the lower limit value of the command control voltage Vol is 2.5 V.
Is set and the process proceeds to step S22. In step S22, the assist control flag Volflg is set to 2 (left-turn assist).

In step S22, 4.5V is output to the solenoid portion 103a of the first control valve 103, and the second control
The command control voltage Vol is output to the solenoid portion 103a of the control valve 104 of FIG. That is, as shown by the dotted line in FIG.
A command control voltage Vol corresponding to the vehicle speed Vel is output to the second control valve 104, a hydraulic pressure is generated according to the command control voltage Vol, and an assist force in the left-turn direction is generated (FIG. 14B). ). 4.5V for the first control valve 103
Is output, and the hydraulic pressure is not generated so that the assisting force in the right-turning direction is not generated (FIG. 14 (a)).

The direction determining routine Tq-OUT0 in step S13 will be described with reference to FIG.

In step S24, the command control voltage Vol is set to V
ol + C (predetermined value) is set, and it is determined in step S25 whether the command control voltage Vol is 4.5 V or higher. When the command control voltage Vol is 4.5 V or more, the command control voltage Vol is set to 4.5 V (upper limit value setting) in step S26, and the process proceeds to step S27. When it is less than 4.5 V, the process directly proceeds to step S27.

In step S27, the assist control flag Vo
It is determined whether lflg is 1 or not. If it is determined in step S27 that the assist control flag Volflg = 1, step S27
At 28, the command control voltage Vol is output to the first control valve 103 and 4.5V is output to the second control valve 104. That is, as indicated by the solid line in FIG. 15, the steering wheel angle θh is small (less than 10 deg) at this time, so
About 4.5V is output to the control valve 103, so that the hydraulic pressure is hardly generated and the assisting force in the right-turning direction is hardly generated (FIG. 15A). Second control valve 10
4.5V is output to 4 so that hydraulic pressure is not generated and assisting force in the left turning direction is not generated (FIG. 15).
(B)).

In step S29, it is determined whether or not the assist control flag Volflg is 2 in step S29.
When it is determined in step S29 that the assist control flag Volflg = 2, 4.5 V is output to the first control valve 103 and the command control voltage Vol is output to the second control valve 104 in step S30. That is, as shown by the dotted line in FIG. 15, 4.5V is output to the first control valve 103,
The hydraulic pressure is not generated, and the assisting force in the right turning direction is not generated (FIG. 15 (a)). Further, since the steering wheel angle θh is small at this time, the second control valve 104 has approximately 4.
5V is output so that the hydraulic pressure is hardly generated and the assisting force in the left turning direction is hardly generated (Fig. 15).
(B)).

As described above, the command control voltage Vol is determined according to the steering direction of the steering wheel 13, the steering amount, and the vehicle speed Vel.
Is set and the first and second control valves 103 and 104 are operated according to the command control voltage Vol, so that the assist force can be generated according to the running state of the vehicle, and the steering operation load is increased. Can be reduced.

Further, since the assisting force is generated by the pressure oil output from the rotary valve 16, the assisting force corresponding to the steering force (steering torque) of the steering wheel 13 can always be obtained, and the command control voltage can be obtained. It is not necessary to use steering torque information when setting Vol.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 17 shows the overall configuration of the power steering apparatus according to the second embodiment of the present invention. Incidentally, FIG.
The same members as the members shown in FIG.

The flow paths 28 and 29 are branched, and the flow paths 101 and 102 for connecting the first and second inlet / outlet bodies 54 and 55 of the valve drive actuator 15 are provided. Channel 1
A control valve 110 as a solenoid valve is provided at 01 and 102, and when one control valve 110 is operated, the hydraulic pressure corresponding to the steering torque output from the rotary valve 16 is changed to the first and second control valves.
It is adapted to be supplied to the inlet / outlet bodies 54 and 55. The return port 111 of the control valve 110 is connected to the flow path 34 and is connected to the oil reservoir 35. The control valve 110 is provided with two input ports 201 and 202 and two output ports 203 and 204. Input port 201
When the pressure oil is sent from the output port 203 to the output port 203, that is, when the pressure oil is sent from the output port 21 of the rotary valve 16 to the first inlet / outlet body 54 of the valve drive actuator 15, the assisting force at the time of right turn is obtained. Input port 202
When pressure oil is sent from the output port 204 to the output port 204, that is, when pressure oil is sent from the output port 22 of the rotary valve 16 to the second inlet / outlet body 55 of the valve drive actuator 15, an assist force for left turning is obtained. It is designed to be used. Then, the oil pressure of the pressure oil when obtaining the assist force is adjusted according to the voltage value applied to the solenoid portion 110a of the control valve 110.

The control valve 110 will be described with reference to FIGS. 18 to 21 by taking the case of right turning as an example. As the control valve 110, a valve whose axial force increases as the voltage value applied to the solenoid 110a increases is used. FIG. 18 shows the maximum axial force, and FIG. 19 shows the medium axial force.
FIG. 20 shows cases where the axial force is zero.

The control valve 110 has input ports 201, 20
2 and output ports 203, 204 are formed, and a return port 111 is formed for each output port 203, 204. The control valve 110 has a solenoid portion 11
A piston 112 that moves in the axial direction by the excitation of 0a is provided, and the piston 112 is biased in one direction (left direction in the figure) by a return spring 113. Piston 112
Three large diameter portions 114a, 114b, 114c and two small diameter portions 115a, 115b are formed in the.

As shown in FIG. 18, the solenoid portion 110
When the piston 112 is maximally moved in the axial direction (rightward in the figure) against the biasing force of the return spring 113 due to the excitation of a, the two return ports 111 are closed by the large diameter portions 114a and 114b of the piston 112. , The input ports 201 and 202 by the small-diameter portions 115a and 115b.
And the output ports 203 and 204 are fully opened.
As shown in FIG. 20, the piston 112 has a return spring 113.
When the piston 112 is moved in the axial direction (leftward in the figure) only by the urging force of the pistons 112, the large diameter portions 114b and 114c of the piston 112 cause the input ports 201 and 202 and the output ports 203 and 2 to move.
04 and the small diameter portion 115a, 11
The two return ports 111 are opened by 5b. In addition, as shown in FIG.
When the piston 112 moves to the intermediate portion in the axial direction against the urging force of the return spring 113 due to the excitation of the
The two large diameter portions 114a and 114b close the two return ports 111 and the large diameter portions 114b and 114b.
Input port 201, 202 and output port 2 by 4c
The state between 03 and 204 is half closed. Therefore, the flow rate of the pressure oil between the input ports 201 and 202 and the output ports 203 and 204 is adjusted according to the voltage output to the solenoid part 110a, and the assist force by the valve drive actuator 15 is adjusted.

The control operation when the above-mentioned control valve 110 is used will be described with reference to FIG. In this control operation, the steering force setting routine of step S6 in the flowchart shown in FIG. 7 is executed as shown in FIG.

Depending on the steering direction, the pressure oil from the rotary valve 16 passes through the flow passage 28 or the flow passage 29 and the control valve 11
Sent to 0. In the present embodiment, description will be given by taking as an example the case of right cutting when pressure oil is sent to the flow path 28. After the neutral signal (Hc value) of the steering wheel 13, the steering wheel angle θh, the vehicle speed Vel and the steering wheel angular velocity θhs are read, the steering force setting routine shown in FIG. 21 is executed to set the steering force according to the steering situation. .

As shown in FIG. 21, in step S41, a steering force total coefficient (coefficient) KK is calculated based on the assist control coefficient KV1, the phase advance coefficient Kh-V, and the steering wheel angular velocity θhs. That is, KK = 50KV1 + Kh−V · | θh
The coefficient KK is calculated by s | / 5. The assist control coefficient KV1 is set to the relationship shown in FIG. 13 with the vehicle speed Vel as described above.

After the coefficient KK is calculated in step S41, the absolute value of the coefficient | KK from 4.5V is calculated in step S42.
The command control voltage Vol is set to a value obtained by subtracting |. In step S43, it is determined whether the command control voltage Vol is less than 2.5V, and if it is less than 2.5V, step S4.
In step 4, the command control voltage Vol is set to 2.5 V (lower limit value setting), and the process proceeds to step S45. If 2.5 V or more, the process directly proceeds to step S45.

In step S45, the command control voltage Vol is output to the solenoid portion 110a of the control valve 110. As a result, the piston 1 of the control valve 110 is axially moved according to the voltage value.
12 moves against the biasing force of the return spring 113,
The pressure oil sent from No. 8 is supplied to the valve drive actuator 15 via the input port 201 and the output port 203 to generate the assisting force in the right turning direction. When turning left, pressure oil from the rotary valve 16 is sent to the control valve 110 via the flow path 29, and pressure oil is supplied to the valve drive actuator 15 via the input port 202 and the output port 203. Generates the assist power of.

When the command control voltage Vol is approximately 4.5V,
As shown in FIG. 18, the piston 112 has a return spring 113.
The maximum movement is made in the right direction in the figure against the urging force of (1), and the state between the input port 201 and the output port 203 is fully opened. As a result, all the pressure oil from the flow path 28 is supplied to the valve drive actuator 15, and a large assist force is obtained.

Command control voltage Vol is 4.5V and 2.5V
In between (for example, 3.5V), as shown in FIG.
The piston 112 moves to the intermediate portion in the axial direction against the urging force of the return spring 113, and the input port 201 and the output port 2
It will be in a half-open state with 03. As a result, the pressure oil from the flow path 28 is throttled and supplied to the valve drive actuator 15, and a moderate assist force is obtained.

When the command control voltage Vol is 2.5 V, as shown in FIG. 20, the piston 112 moves leftward in the figure only by the urging force of the return spring 113, and the input port 2
01 and the output port 203 are fully closed. As a result, the pressure oil from the flow path 28 is not supplied to the valve drive actuator 15 and no assist force is generated.

As described above, similarly to the first embodiment, the assisting force can be generated according to the running state of the vehicle and the assisting force according to the steering torque of the steering wheel 13 can be obtained. Further, since the supply amount of the pressure oil is controlled by one control valve 110, it is not necessary to detect the steering direction of the handlebar 13, and the number of members can be reduced to simplify the control.

[0075]

In the power steering apparatus for a vehicle of the present invention, the hydraulic pressure output from the rotary valve at the time of steering operation of the steering wheel is used as the drive source of the valve drive mechanism for generating an independent torsion moment in the torsion bar. The assist force can always be obtained by the hydraulic pressure generated according to the steering torque of the steering wheel, and it is not necessary to control the hydraulic pressure based on the steering torque. As a result, a member that divides the hydraulic pressure and a sensor member that detects the steering torque are not required according to the steering direction of the steering wheel, and the number of parts can be reduced and the control can be simplified.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a power steering device according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a steering mechanism.

FIG. 3 is a view taken along the line III-III in FIG.

FIG. 4 is a view taken along the line IV-IV in FIG.

FIG. 5 is an explanatory view of the action of hydraulic pressure on a hydraulic chamber.

FIG. 6 is an operation explanatory view of the plunger corresponding to FIG.

FIG. 7 is a control flowchart of the power steering device.

FIG. 8 is a control flowchart of the power steering device.

FIG. 9 is a control flowchart of the power steering device.

FIG. 10 is a control flowchart of the power steering device.

FIG. 11 is a control flowchart of the power steering device.

FIG. 12 is a graph showing the relationship between a phase advance coefficient and vehicle speed.

FIG. 13 is a graph showing the relationship between the assist control coefficient and the vehicle speed.

FIG. 14 is a graph showing the characteristics of the command control voltage depending on the vehicle speed.

FIG. 15 is a graph showing the characteristics of the command control voltage depending on the vehicle speed.

FIG. 16 is a graph showing the relationship between the command control voltage and the steering wheel angle depending on the vehicle speed.

FIG. 17 is an overall configuration diagram of a power steering device according to a second embodiment of the present invention.

FIG. 18 is an explanatory diagram of a control valve.

FIG. 19 is an explanatory diagram of a control valve.

FIG. 20 is an explanatory diagram of a control valve.

FIG. 21 is a control flowchart of the power steering device.

FIG. 22 is an overall configuration diagram of a conventional power steering device.

[Explanation of symbols]

 1 Steering Mechanism 7 Power Cylinder Device 8 Front Wheel 9 Torsion Bar 11 Input Shaft 13 Handle 15 Valve Drive Actuator 16 Rotary Valve 28,29 Flow Path 33 Oil Pump 42 Overhang 70 Control Unit 103 First Control Valve 104 Second Control Valve 110 control valve

Claims (1)

[Claims] 1. An input shaft connected to a steering wheel side and an output shaft connected to a steered wheel side, which are coaxially rotatably supported in a housing and rotatably connected to each other via a torsion bar. A steering mechanism that steers the steered wheels in accordance with a steering operation of the steering wheel; a hydraulic pressure generation unit that generates a predetermined hydraulic pressure; and a steering mechanism that is provided between the input shaft and the output shaft of the steering mechanism. A valve means that is connected to the hydraulic pressure generation unit and outputs hydraulic pressure by relative displacement according to the twist of the torsion bar during steering operation of the steering wheel; Of the input shaft or the output shaft, and the cylinder mechanism that drives the steered wheels in the steering direction by the hydraulic pressure from the valve means acting on one of the chambers. At least on one side, the pressed portion provided so as to project in the radial direction of the shaft is connected to the left and right chambers of the cylinder mechanism, and the pressed portion is driven by the hydraulic pressure acting on the left and right chambers. Has a pusher provided on at least the other side of the input shaft or the output shaft so as to be able to push in the circumferential direction, and the twisting moment independent of the torsion bar by the pushing of the pushed portion by the driving of the pusher. And a solenoid valve provided between the cylinder mechanism and the presser,
Setting a target assist force of an assist force obtained by rotating the valve means in the same direction as the torsion direction of the torsion bar, and a pusher driving means for controlling a hydraulic pressure acting on the pusher by exciting the electromagnetic valve. And a control means for exciting the solenoid valve so as to drive the pusher of the valve mechanism so as to obtain the target assist force during steering operation of the steering wheel. Steering device.