JPH05112248A - Power steering device for vehicle - Google Patents

Abstract

PURPOSE:To improve straight running ability and maneuvering stability by steering a steering wheel, on which an assist force is exerted, by a first steering angle mechanism through operation of a handle, controlling a different steering angle mechanism by means of a correction steering angle value responding to a steering angle state, and effecting microcorrection of a steering angle according to the occurrence of disturbance to adsorb disturbance. CONSTITUTION:A hydraulic assist mechanism comprising a power cylinder device 7, a rotary valve 30, an oil pump 46, and a reservoir tank 47 is mounted on a first steering angle mechanism (steering gear) 2 to steer a steering wheel. An assist force is controlled by means of a controller 100, a reaction force mechanism 20, and a pressure control valve 50 and steering is effected by the first steering mechanism 2. Meanwhile, by switching an electromagnetic switching valve 95 to positions A-C, a second steering angle mechanism (microsteering angle mechanism) 70 effects microcorrection of the steering angle of front wheels 8 independently of operation by a handle 18 and within a range of a given angle determined by a gap between a recessed part 76 and a protrusion part 77. Thus, a fluctuation owing to disturbance is absorbed by the microsteering angle mechanism 70 and straight advancing ability and maneuvering stability are improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle power steering apparatus used for steering front wheels of an automobile, for example.

[0002]

2. Description of the Related Art An automobile (vehicle) is equipped with a hydraulic power steering device for steering with a light operation.

In such a power steering system, a steering mechanism (first steering angle mechanism) for steering the front wheels (steering wheels) to the left and right in accordance with the steering operation from the steering wheel is provided.
Oil pump, rotary valve, power cylinder device,
Providing a hydraulic pressure assist system (hydraulic pressure assist mechanism) composed of flow paths that connect each component, and supplying hydraulic pressure obtained by a rotary valve that is displaced by rotation of the handle to the power cylinder device to generate an assist force. Is being carried out. However, the handle force cannot be properly controlled only by the displacement of the rotary valve.

Therefore, in the conventional power steering system, the assist force is variable by providing a reaction force mechanism for varying the reaction force in the assist system and a control valve (control means) for controlling this reaction force mechanism. To
An appropriate steering characteristic is obtained by controlling using a sensor that detects the vehicle speed of the automobile and a sensor that detects the steering wheel angle. For example, the steering force is appropriately increased to make the steering wheel force lighter when steering in the stationary range and the low-speed traveling range, and conversely, made to be appropriately reduced to make the steering wheel force heavier when steering in the medium-high speed traveling range. ..

[0005]

By the way, in the power steering system of a vehicle, there are cases in which the straight running stability is impaired or the steering stability is impaired under the influence of disturbance. This can be seen, for example, in road conditions, side winds, and even during steer steering.

However, conventionally, there is no device for controlling the assisting force and the steering angle (fine region) in an integrated manner in a power steering device for an automobile, and the power steering device is capable of avoiding the influence of disturbance. Is required.

The present invention has been made by paying attention to such a situation, and an object thereof is to appropriately control the assist force and appropriately control the steering angle correction according to the steering angle situation. An object of the present invention is to provide a vehicle power steering device that can be integrated.

[0008]

In order to achieve the above object, a vehicle power steering apparatus of the present invention is provided with a first steering angle mechanism for steering steered wheels in accordance with a steering operation from a steering wheel. The steering angle mechanism is equipped with a hydraulic assist mechanism that assists the steering of the steered wheels with hydraulic pressure.
The hydraulic assist mechanism is provided with control means for varying the assist force generated by the hydraulic assist mechanism, and the control means is controlled according to the steering state.
And a second control means for controlling the first steering angle mechanism to control the steering wheel independently of the first steering angle mechanism.
And a setting means for setting a corrected steering angle value according to the situation at the time of the steering operation, and a second steering angle mechanism for controlling the second steering angle mechanism according to the corrected steering angle value of the setting means.
The control means is provided.

[0009]

According to the vehicle power steering device of the invention, when the steering wheel is steered, the steered wheels are steered by the first steering angle mechanism while obtaining the assist force generated by the control of the first control means. ..

At this time, the operation of the second steering angle mechanism is the second
The control means is controlled according to the corrected steering angle value according to the steering angle situation, and when a disturbance occurs, the steered wheels are slightly steered in response to the disturbance to avoid the influence of the disturbance.
In other words, by controlling the assist force and the steering angle correction in an integrated manner,
Improve straight running stability and steering stability.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment shown in FIGS.

FIG. 1 shows the configuration of a power steering device for steering the left and right front wheels (steering wheels) of an automobile. Reference numeral 2 denotes a steering mechanism 1 such as a rack and pinion type steering gear (first steering angle mechanism). is there.

As shown in FIG. 2, the steering gear 2 has a structure in which a rack 4 and a pinion 5 are built in a casing 3, for example. One end of the rack 4 is connected to one front wheel (not shown) of the automobile via a steering rod 6, a tie rod, and a knuckle (all not shown). On the other end, the steering rod 6, the power cylinder device 7, the tie rod,
It is connected to the other front wheel 8 (steering wheel) of the automobile via a knuckle (neither is shown). The pinion 5 of the steering gear 2 is the transmission shaft portion 2 of the steering mechanism 2.
It is connected to a.

That is, the transmission shaft portion 2a is arranged along the vertical direction, and this is the input side torsion bar portion 9a.
And a torsion bar portion 9b on the output side, a two-stage torsion bar 9 in which two torsion bar portions are connected in series along the axial direction, and a hollow shaft fitted to the outer peripheral portion of the torsion bar 9. Consists of. The torsion bar 9 has a torsional rigidity of the first torsion bar portion 9a set to be "5 to 10 times or more" higher than the torsional rigidity of the second torsion bar portion 9b.

Here, the hollow shaft will be described. It is composed of an input shaft 11a into which the input side end of the input side torsion bar portion 9a is inserted, an input side torsion bar portion 9a and an output side torsion bar portion 9b. The intermediate shaft 11b into which the intermediate portion is inserted, and the output shaft 11c into which the output side end of the output side torsion bar portion 9b is inserted. And
The shafts 11a to 11c arranged in the axial direction are rotatably connected to each other. Specifically, the lower end portion of the input shaft 11a and the upper end portion of the intermediate shaft 11b are formed by inserting the upper end portion of the intermediate shaft 11b into the shaft end of the input shaft 11a and rotatably supporting the both. Are connected with. Similarly, the lower end of the intermediate shaft 11b and the upper end of the output shaft 11c are also connected by inserting the lower end of the intermediate shaft 11b into the shaft end of the output shaft 11c and rotatably supporting the both. ing. The upper end of the input shaft 11a is fixed to the upper end of the input side torsion bar portion 9a with a pin 14. Intermediate shaft 11b
The lower end of is fixed to the intermediate portion between the input side torsion bar portion 9a and the output side torsion bar portion 9b with a pin 15. Further, the lower end of the output shaft 11c is fixed by a pin 16 to the lower end of the output side torsion bar portion 9b. A pinion 5 that meshes with the rack 4 is provided on the lower outer peripheral portion of the output shaft 11c.

The upper end of the torsion bar 9 and the input shaft 11a are connected to the steering shaft 17. The end of the steering shaft 17 is connected to the handle 18 as shown in FIG.
Input the rotational displacement from the steering shaft 1
The front wheels 8 and 8 (only one of which is not shown) are steered (steering angle) via the 8, the torsion bar 9, the pinion 5, the rack 4, and the steering rod 6.

Inside the housing 19 installed above the casing 3 so as to surround the intermediate shaft 11b, the reaction force mechanism 20 (control means), the rotary valve 30, the minute steering angle mechanism 70 (second steering angle) Mechanism) is provided in order. Reference numeral 19a denotes a lid body screwed to the opening of the housing 19 so as to close the upper opening of the housing 19, and the lid body 19a is connected to the input side torsion bar portion 9a.
And the upper end of the input shaft 11a penetrates.

The rotary valve 30 includes an intermediate shaft 11b.
A cylindrical inner valve 31 is provided on the outer periphery of the middle stage,
On the inner surface of the housing 14 corresponding to the outer peripheral surface of the inner valve 31, a cylindrical outer valve 32 that is combined with the inner valve 31 is rotatably provided. That is,
The rotary valve 30 is configured such that when the torsion bar 9 is twisted by the handle force from the handle 18, a relative displacement is generated between the outer valve 32 and the inner valve 31. The outer valve 32 is connected to the upper end of the output shaft 11c via a pin 44.

As shown in FIG. 1, the outer valve 32
The inflow port 32a formed on the inner valve 31 communicates with the inflow port 33a provided on the housing 19, and the outflow port 31a formed on the inner valve 31 communicates with the outflow port 34 provided on the housing 19. Also outer valve 1
An output port (not shown) formed in 7 communicates with a pair of output port portions 35 and 36 provided in the housing 19. These output port portions 35 and 36 are connected to the power cylinder device 7.

The power cylinder device 7 will now be described. As shown in FIG. 1, the power cylinder device 7 has a piston rod 38 slidably provided so as to penetrate a cylinder 37.
A piston 39 is provided in a part of the piston rod 38 so as to partition the cylinder 37 into both sides (left and right) in the longitudinal direction. Left and right chambers 37 partitioned by this piston 39
a pair of input ports 40 and 41 communicating with a and 37b,
The output ports 35 and 36 are connected via the flow paths 42 and 43.

Then, the inflow port body 33 is connected to the automobile through the flow passage 48 and the flow dividing unit 45 (one inlet portion 45a and two outlet portions 45b, 45b are connected by a passage 45c with an orifice). Pump 46 with a relief valve driven by a running engine (not shown)
And the outlet body 34 is connected to the oil reservoir 47 via the flow path 49, and constitutes a hydraulic circuit for the power cylinder device 7. With this hydraulic circuit,
According to the relative displacement between the outer valve 32 and the inner valve 31 in the rotary valve 30, the rotary valve 30 can supply the hydraulic pressure according to the steering force and the steering direction to the chambers 37a, 37b of the power cylinder device 7. That is, the front wheels 8, 8 can be steered while hydraulically assisting the steering wheel force (hydraulic assist mechanism). As the oil pump 46, a pump having a characteristic that the discharge flow rate to the rotary valve 30 changes according to the pump rotation speed is used.

The reaction mechanism 20 will be described below.
As shown in FIG. 2, the pressed portion 21 is attached to the outer peripheral surface of the end portion of the intermediate shaft 11b into which the shaft end of the output shaft 11c is inserted.
Is formed.

That is, as shown in FIG. 1, the pressed portion 21 has four recesses 22 on the outer peripheral surface of the end portion of the intermediate shaft 11b.
Are formed at equal intervals in the circumferential direction. This pressed portion 21
A large-diameter holder portion 24, in which a reaction force plunger 23 is movably installed, is formed in a peripheral wall portion around the shaft end of the output shaft 11c at a position facing the position of each recess 22. A concave portion 22 is provided at the tip of each reaction force plunger 23.
A convex portion 25 that engages with is provided. A chamber 25 is formed behind each reaction force plunger 23.
Each chamber 25 has an inlet 27 provided in the housing 19.
Through the annular flow path 28,
By supplying the hydraulic pressure from 7, the reaction force plungers 23 can press the pressed portion 21 as if they were sandwiched. That is, as the hydraulic pressure in each chamber 25 increases, the intermediate shaft 11b is strongly pressed. As a result, a feeling of reaction (reaction force) is generated in the handle 13.

A pressure control valve 50 (control means: hereinafter referred to as PCV50) for controlling the supply pressure of the reaction force mechanism 20 is integrated with the housing 19 along with the torsion bar 9.

The PCV 50 will be described below.
The PCV 50 is incorporated in a bulging portion 51 formed in a part of a side portion of the housing 19 as shown in FIG. The PCV 50 has a spool valve element 5 in a cylindrical cylinder space 52 formed in the housing 19 along the vertical direction.
3 is provided slidably. This spool valve body 5
The lower end of 3 is connected to a plunger 55 of a solenoid 54 installed below the bulge 51,
In accordance with the excitation control of No. 4, the spool valve body 53 is structured so that it can be displaced upward in its entirety. The spool valve body 5
3 is a spring 56 provided at the upper end of the cylinder space 52
It returns due to the elastic force of.

Belt-shaped annular grooves 57 and 58 are formed on the outer peripheral surface on the upper stage side and the outer peripheral surface on the lower stage side of the spool valve body 53. An annular groove 57 is provided inside the spool valve body 53.
A through-passage 59 is formed so as to communicate with the annular groove 58. Further, the communication state with the inflow port 60 provided in the housing 19 can be varied between the annular groove 57 and the peripheral surface portion around the annular groove 57. The inflow port 60 communicates with a flow path 61 (shown only in FIG. 1) formed in the housing 19 and connected to the oil pump 46. The annular groove 58 is always in communication with the output port 62 provided in the housing 19. The output port 62 is connected to the inflow port 27 of the reaction mechanism 20 via a flow passage 63 provided in the housing 19.

The setting of the annular groove 57 and the inflow port 60 is as follows.
When the axial force of the plunger 55 is the largest (the plunger 5
5 is the most protruding state; for example, the Max current value, and the inflow port 60 is blocked (closed). As the axial force of the plunger 55 becomes smaller (current value becomes smaller) (the plunger 55 becomes The annular groove 57 and the inflow port 60 are communicated with each other, and the communication area at that time is increased. This allows the solenoid 5
According to the excitation of No. 4, a feeling of reaction (reaction force) is generated in the handle 13 (assist force: small).
A drain passage 64 is formed inside the spool valve body 53 so as to pass through a coaxial center portion for drain.
The drain passage 64 connects to the oil reservoir 47 via the outflow port 65 provided in the housing 19.
6 (provided in the housing 19).

On the other hand, the micro rudder angle mechanism 70 will be described. The micro rudder angle mechanism 70 has a large diameter hollow portion 71 surrounding the upper intermediate shaft portion of the inner valve 31 under the input shaft 11a. is doing. The upper and lower portions of the outer peripheral portion of the large-diameter portion 71 are, via bearings 72 and 73, the upper inner peripheral surface of the housing 19 and the inner surface of the lid 19a whose radial dimension is increased corresponding to the large-diameter portion 71. It is rotatably supported on. An inner sleeve 74 is provided on the outer peripheral surface of the large diameter portion 71.
Is fitted. An outer sleeve 75 is rotatably fitted on the inner peripheral surface of the housing 19 facing the inner sleeve 74.

Inside the large-diameter portion 71, as shown in FIGS.
As shown in FIG.
Flat recesses 76 extending outward in the radial direction are respectively formed from two symmetrical points separated by 0 degree. The recess 76 is open at the lower end of the input shaft 11a.

At the upper portion of the intermediate shaft 11b covered with the large diameter portion 71, as shown in FIGS.
Plate-like projecting portions 77 projecting outward in the radial direction are respectively formed from two symmetrical points separated by 80 degrees. The overhanging portion 77 is formed in an outer shape smaller than the outer shape of the recess 76. The projecting portion 77 is concentrically loosely fitted in the recess 76. The overhang 77 and the recess 76
The clearance between and is set to such a dimension that a minute steering angle range necessary for steering angle correction can be set, and the intermediate shaft 11b can rotate within a predetermined angle range with respect to the input shaft 11a.

Further, in the large-diameter portion 71, as shown in FIGS. 3 to 5, concave portions are symmetrically formed in an outer peripheral portion sandwiching the end portion of the concave portion 67, and the same portion is sealed by an inner sleeve 74. 4 hydraulic chambers 78 having a substantially triangular cross section,
Forming 79. Of these four hydraulic chambers, the two on the rear side in the clockwise direction with respect to the concave portion 76 are
The two chambers on the front side in the clockwise direction with respect to the hydraulic chamber 78 and the concave portion 76 will be referred to as a second hydraulic chamber 79.

Plunger guide holes 80 are formed in the upper and lower stages in the wall portion between the recess 76 and the first hydraulic chamber 78 at positions corresponding to the plate surface portion of the overhanging portion 77 as shown in FIG. ing. A first plunger 81 is fitted in each of the plunger guide holes 80 so as to be slidable in the axial direction. Further, these plungers 81 are urged by a leaf spring 82 installed in the first hydraulic chamber 78 in a direction projecting into the concave portion 76, and the abutting portions 77 set the overhanging portion 77 to a neutral (position) state by each contact. Is done.

Similarly, in the wall portion between the concave portion 76 and the second hydraulic chamber 79, the plug guide holes 83 are formed in two steps in the vertical direction at positions corresponding to the plate surface portion of the overhanging portion 77. .. Then, second plungers 84, which are the same as the first plunger 81, are fitted in the plunger guide holes 83 so as to be slidable in the axial direction. These second plungers 84 are also
Similarly, a leaf spring 85 installed in the second hydraulic chamber 79 urges the concave portion 76 in a protruding direction. The second plungers 84 are arranged symmetrically with the first plunger 81, and similarly, the projections 77 are positioned in a neutral (positional) state together with the first plunger 81 by each contact.

A first annular oil passage 86 is provided at the upper portion of the outer peripheral surface of the inner sleeve 74, and a second annular oil passage 87 is provided at the lower portion thereof. Then, the first annular oil passage 86
3 communicates with the two first hydraulic chambers 78 via first hole-shaped oil passages 88 respectively provided in the inner sleeve portions corresponding to the positions of the first hydraulic chambers 78 as shown in FIG. .. Further, the second annular oil passage 87 is provided with two second hydraulic chambers via a second hole-shaped oil passage 89 provided in the inner sleeve portion corresponding to the position of each second hydraulic chamber 79 as shown in FIG. 7
It communicates with 9.

A first annular oil passage 90 is provided in the upper portion of the outer peripheral surface of the outer sleeve 75, and a second annular oil passage 91 is provided in the lower portion. In addition, 92 is the first annular oil passage 9
0 is an O-ring for oil passage sealing provided in the upper stage of 0, between the first annular oil passage 90 and the second annular oil passage 91, and in the lower stage of the second annular oil passage 91.

The first annular oil passage 90 of the outer sleeve 75 is communicated with the first inlet / outlet body 93 (shown only in FIG. 1) formed in the housing 19, and the second annular oil passage 91 of the outer sleeve 75 is connected to the housing 19. The second inlet / outlet body 94 (shown only in FIG. 1) formed in the above.

These inlet / outlet bodies 93, 94 are connected to another outlet 45b of the flow dividing unit 45 and an oil reservoir via a switching valve, for example, an electromagnetic switching valve 95 for switching four ports and three positions and flow paths 96, 97. 47, and by switching the electromagnetic switching valve 95, the flow dividing unit 45 is connected.
The oil pressure from the oil pump 46 divided by is supplied to the inlet / outlet body 93 or the inlet / outlet body 94. Incidentally, 96a is an orifice provided in the flow path 96.

Further, the first annular oil passage 86 of the inner sleeve 74 and the first annular oil passage 90 of the outer sleeve 75 are in a direction perpendicular to the portions where the first hole-shaped oil passages 88, 88 are located. A first communication hole 98 provided in the portion,
It communicates via 98. Inner sleeve 7
The second annular oil passage 87 of No. 4 and the second annular oil passage 87 of the outer sleeve 75 are provided in the outer sleeve portion which is in a direction perpendicular to the portion where the second hole oil passages 89, 89 are located.
It is communicated through the communication holes 99, 99 so that the supplied hydraulic pressure does not suddenly act on the hydraulic chambers 78, 79.

With the flow path thus configured, when the electromagnetic switching valve 95 is at the central switching position A, hydraulic pressure is prevented from acting on the first hydraulic chambers 78, 78 and the second hydraulic chambers 79, 79. ing. That is, at this time, no twist is generated in the input side torsion bar portion 9a, and the overhanging portion 77 of the intermediate shaft 11b as shown in FIGS. 3 and 4 is located in the circumferential center of the concave portion 76 of the input shaft 11a. It is in a neutral position.

Further, when the electromagnetic switching valve 95 is in the switching position B in which the flow direction is opposite, the pressure oil from the oil pump 46 is supplied to the first hydraulic chambers 78, 78, and as shown in FIG. The 1st plunger 81, 81 presses the overhanging portion 77 and twists the input side torsion bar portion 9a.
b is rotated rightward (clockwise) with respect to the input shaft 11a. That is, at this time, the steering amount to the right of the steering mechanism 1 increases and the steering amount to the left decreases.

Further, at the switching position C where the electromagnetic switching valve 95 remains, the pressure oil from the oil pump 46 is supplied to the second hydraulic chambers 79, 79, and as shown in FIG. The overhanging portion 77 is pressed by 84, the input side torsion bar portion 9a is twisted in the opposite direction, and the intermediate shaft 11b is rotated leftward (counterclockwise) with respect to the input shaft 11a. That is, at this time, the steering amount to the left of the steering mechanism 1 increases and the steering amount to the right decreases.

That is, by controlling the switching operation of the electromagnetic switching valve 95, that is, switching from the switching position A to the switching position B or the switching position C (including the energization time), the handle 1 is operated.
Independent of the steering operation from 8, the steering angle of the front wheels 8, 8
The correction can be made minutely within a range of a predetermined angle determined by the gap between the concave portion 76 and the projecting portion 77.

On the other hand, the solenoid 54 and the solenoid portion 95a of the electromagnetic switching valve 95 have a controller 10 including a microcomputer and its peripheral circuits.
0 (corresponding to setting means, first control means, second control means) is connected. This controller 100 has
For example, a lateral G sensor 10 provided at the front of the vehicle body of an automobile to detect acceleration (lateral acceleration) in the vehicle width direction that acts on the vehicle body.
1, a vehicle speed sensor 102 for detecting the traveling speed of an automobile, a steering angle sensor 103 for detecting the steering angle of the steering wheel 18, and a steering angular velocity sensor 1 for detecting the steering angular velocity of the steering wheel 18
04, a mode selector switch 105 for switching the response between the normal mode and the sports mode is connected.

By using this control system, the assist force is changed according to the steering state, and the steering angle of the front wheels 8 is momentarily corrected when the steering wheel 18 is turned back during the sudden steering (to avoid the influence of disturbance). To correct the steering angle). Therefore, the controller 100 has the following functions.

That is, in order to control the assist force, the controller 100 is set with a vehicle speed map in which the control current value of the solenoid 54 according to the vehicle speed is divided into modes (normal, sports) as shown in FIG. And
The appropriate assist force can be detected.

The controller 100 has a function of judging whether the mode is the normal mode or the sports mode from the ON / OFF state of the mode changeover switch 105, and a function of reading a control current value according to the vehicle speed during the steering operation in the judged mode.
A function for exciting the solenoid 54 is set according to the read control current value, and the steering force is changed depending on how much the reaction force plunger 23 is pressed against the intermediate shaft 11b.

Further, the controller 100 has a map of each control gain as shown in FIG. 13 which is determined by the vehicle speed and the steering angular velocity as shown in FIG. 11 in order to instantaneously correct the steering angle of the front wheels 8. A map of a control gain defined by a vehicle speed and a steering angular velocity, which is a reference of a relationship to be compared with this map, and a set value of lateral acceleration for detecting a sudden change of the vehicle body are set.

Further, the controller 100 has a function of judging whether it is the time of cutting or returning from the sensor detection, a function of comparing the detected values read in the above map, and a comparison between the detected lateral acceleration and the set lateral acceleration. Functions are set, and it is possible to detect that abrupt cutting back is performed after abrupt cutting is performed by these functions.

Further, the controller 100 has a function for obtaining a steering angle correction value according to the above steering situation,
In the case where a function for switching the electromagnetic switching valve 95 to the switching position A or the switching position C according to the steering angle correction value is set, and a sudden cut-back is performed after a sharp cutting is performed, The fine rudder angle mechanism 70 is used to change the degree of rudder angle (to improve the convergence of the yaw rate). The flowchart in FIG. 8 shows the control operation in the controller 100. Next, the control operation in the controller 100 will be described with reference to a flowchart.

The controller 100 is activated by the ON signal of the ignition key switch of the automobile. Then, first, in step S1, initialization is performed, and the return flag θFLG, the correction flag RFLG, and the control level memory MCL are each set to “0”.

After that, in steps S2 to S4,
The vehicle speed V detected by the vehicle speed sensor 102 and the steering angular speed θ of the steering wheel 18 detected by the steering angular speed sensor 104.
The lateral acceleration YG detected by the H and lateral G sensors 101 is read. After step S4, the process proceeds to step S40, and the steering reaction force is controlled according to the reaction force control routine shown in FIG.

That is, in step S41, it is determined from the on / off state of the mode changeover switch 105 whether the current steering mode of the vehicle is the "normal mode" suitable for normal traveling or the "sport mode" suitable for sports traveling. ..

If the "normal mode" is determined at this time, the process proceeds to step S42, and the normal mode diagram of the "vehicle speed-control current" map shown in FIG. 10 corresponds to the current vehicle speed. The control current value A is read.

When it is determined that the "sport mode" is set,
In step S43, similarly, the control current value A corresponding to the current vehicle speed of the vehicle is read from the sports mode diagram of the "vehicle speed-control current" map. Then, in step S43, the read control current value A is supplied to the solenoid 54.

Specifically, when the vehicle speed is low, the solenoid 54 has the largest axial force of the plunger 55, namely 1.0.
A (Max) drive current is supplied. As a result, the plunger 55 of the solenoid 54 projects to the highest position,
The spool valve body 53 of the PCV 50 is held at a position where the inflow port 60 is shut off. In this state, the discharge pressure of the oil pump 46 does not act on each chamber 26 of the reaction force mechanism 20. That is, there is no force for pressing the reaction force plunger 23 against the pressed portion 21 of the intermediate shaft 11b.

When the vehicle speed is high, a drive current of 1.0 A or less is supplied, the current difference and the pragna 55 are held in the lowered position, the inflow port 60 is opened, and the current discharge pressure of the oil pump 46 is reversed. It is supplied to each chamber 26 of the force mechanism 20. That is, when the vehicle speed is high, the pressed portion 21 of the intermediate shaft 11b is pressed by the reaction force plunger 23 by the discharge pressure of the oil pump 46. By such control of the pressing force, the handlebar 13 has an appropriate weight according to the current vehicle speed (appropriate assist force).

After the lapse of step S40, the routine proceeds to step S5, where it is judged if "YG.times..theta.H" is smaller than "0", that is, if the current steering state is the additional steering state. However, this determination is intended to detect the additional cutting state based on the positive / negative relationship (detection direction) of the detected values of the steering angular velocity and the lateral G. Therefore, the lateral increase G can be detected by the above determination. Sensor 101, steering angular velocity sensor 1
The positive / negative of the output of 04 is set.

Here, when the vehicle is in a straight traveling state,
From step S5 to step S6, the correction flag RF
It is determined whether LG is “1”. At first, the correction flag RFLG is "0", so that the process proceeds to step S7.

Next, at step S7, it is judged if the return flag θFLG is "1". Initially, the return flag θFLG is “0”, so the flow proceeds to step S8. In step S8, it is determined whether “YG × θH” is greater than “0”, that is, whether the current steering state is the switchback state. At this time, since the automobile is in a straight traveling state, the process returns to step S2 after step S8, and the processes after step S2 are repeated. Next, it is assumed that the steering wheel 18 is steered from this straight traveling state to generate a lateral G on the vehicle body. Then, “YG × θH” used for the determination in step S5 becomes larger than “0”, and the process proceeds from step S5 to step S9.

In step S9, the value of the control gain a corresponding to the current vehicle speed V and the steering angular speed θH is obtained based on the "vehicle speed-steering angular speed" map shown in FIG. The control level Cθ of the corrected steering angle is calculated by the following equation. Cθ = γ {a · g (1 + KV ² ) / (V ² / L)} ρ where V is the vehicle speed, K is the stability factor, g is the gravitational acceleration, L is the wheelbase of the vehicle body, ρ is the steering gear ratio, and γ is the steering coefficient (constant).

After obtaining the control level Cθ, step S
In step 10, it is determined whether the calculated control level Cθ value is larger than the stored control level memory MCL value.

If the control level Cθ is higher, the process proceeds to step S11, where the value of the control level memory MCL is C.
After rewriting to the value of θ, the process proceeds to step S6. If the control level Cθ is smaller, the process directly proceeds from step S10 to step S6.

Here, as described above, the correction flag RFLG and the return flag θFLG are initially "0" and not in the switchback state. Therefore, the process returns from step S6 to step S7 and back to step S2. After that, the process is repeated. At the same time, the value of the maximum control level Cθ calculated when the handle 18 is turned up is stored in the control level memory MCL by the processing of steps S9 to S11.

Then, the driver turns the wheel 18 from the time of turning.
If you try to return to the straight state by switching back
“Yg × θH” used for the determination in step S8 becomes smaller than “0”, and steps S8 to S1
Go to 2.

In step S12, the reference value of the steering angular velocity with respect to the vehicle speed V at that time is read out based on the map of FIG. In a succeeding step S13, it is determined whether or not the absolute value of the steering angular velocity θH detected by the steering angular velocity sensor 104 is equal to or larger than the reference value obtained in the previous step S11 (that is, the relationship between the vehicle speed V and the steering angular velocity θH is shown in FIG. 12
Is included in the hatched area). At this time, if it is smaller than the reference value, the process returns to step S2.

In step S13, the steering angular velocity θ
When it is determined that the absolute value of H is equal to or greater than the reference value, the process proceeds to step S14, the return flag θFLG is set to "1", and the timing timer Tr is set to "0".

After step S14, step S15
Next, it is determined whether or not the differential value of the output of the lateral G sensor 101, that is, the absolute value of the lateral acceleration YG of the vehicle body is equal to or greater than a predetermined value. When it is determined in step S15 that the absolute value of the lateral acceleration YG is not equal to or larger than the predetermined value, the process returns to step S2 and the process is repeated thereafter.

Since the occurrence of the lateral acceleration YG equal to or more than the set value may be delayed with respect to the occurrence of the steering angular velocity θH equal to or greater than the reference value, the above timing timer Tr is used.

That is, from step S15 to step S
Even if the process returns to step 2, if the process proceeds to step S7 again, the return flag θFLG is set to "1".
Proceed to 16. In step S16, the control period INT is added to the stored value Tr of the timing timer to count the timing timer, and then the process proceeds to step S17. In this step S17, the value Tr of the timing timer
Is determined for a predetermined time Co or not. At this time, if it is longer than the predetermined time Co, the return flag θFLG is reset to “0” in step S18, and then the process returns to step S2.

When the value Tr of the timing timer is smaller than the predetermined time Co, the process proceeds from step S17 to step S15 again, and it is determined whether or not the absolute value of the lateral acceleration change rate Yg is a predetermined value or more. Therefore, the steering angular velocity θH
For a predetermined time C after it is detected that is greater than or equal to the reference value.
By making the determination in step S15 within o, it is possible to deal with the case where the generation of the lateral acceleration change rate Yg is delayed.

If it is determined in step S15 that the absolute value of the lateral acceleration change rate Yg is equal to or larger than the predetermined value, the process proceeds to step S19, and the control level memory MCL is used.
It is determined whether or not the value of is larger than "0".

If it is determined in step S19 that the value in the control level memory MCL is smaller than "0", it is determined that correction steering is not necessary, and the process returns to step S2 to repeat the subsequent processing.

In step S19, the control level memory M
When it is determined that the value of CL is larger than “0”, this means that a steep turn-in steering is performed, and then a sharp turn-back steering is performed, and the lateral G acting on the vehicle body is steep. It is determined to have decreased. In this case, since the yaw-direction swing-back is likely to occur in the vehicle body, the processing for steering angle correction after step S20 is performed.

That is, when it is determined that the value of the control level memory MCL is larger than "0" in step S19, the process proceeds to step S20, and the stored value Tc of the control timer is set to "0", and then in step S21. Correction flag RFLG is set to "1", return flag θFL
G is reset to "0".

Then, in the next step S22,
The output YG of the lateral G sensor 101 is stored in the lateral G memory Myg, and in the subsequent step S23, the control level memory MCL is set as the control amount CCθ that is the target of the correction steering.
Is set and the control level memory MCL is cleared in the next step S24.

After step S24, step S25
After the control period INT is added to the stored value Tc of the control timer to count the control timer, the process proceeds to step S26.

At step S26, the value Tc of the control timer is set.
Is determined to be greater than the predetermined time Ct. When Tc is small, the routine proceeds to step S27, where the steering angle correction value θ ₂ of the front wheels 8 and 8 is calculated by the following equation. θ ₂ = CCθ (Tc / Ct) where CCθ is the control amount and Ct is the rise / fall time.
After the lapse of step S27, the process proceeds to step S28, where the lateral G
It is determined whether the stored value in the memory is rightward (corresponding to a left turn) or leftward (corresponding to a right turn).

If the vehicle is turning to the right (turning to the left), the process proceeds to step S29, and the solenoid portion 9 of the electromagnetic switching valve 95 is arranged so that the front wheels 8 and 8 are corrected and steered to the left by θ _2.
5a is controlled to switch to the switching position B, and the first plunger 8
The intermediate shaft 11 is pressed by the pressing of the overhanging portion 77 by 4, 84.
b is slightly rotated rightward with respect to the input shaft 11a (as shown in FIG. 6). On the other hand, if the vehicle is turning left (turning right), the process proceeds to step S30, where the front wheels 8 and 8 turn right by θ.
The solenoid portion 95a of the electromagnetic switching valve 95 is controlled so that the steering is corrected for ₂ minutes, and the solenoid valve 95 is switched to the switching position C.
1b is slightly rotated leftward with respect to the input shaft 11a (as shown in FIG. 7).

After step S29 or step S30 has passed, the process returns to step S2, but the correction flag RF
Since LG is "1", the process proceeds from step S6 to step S25 to increase the value Tc of the control timer and then to step S26 again.

Here, in the arithmetic expression of step S27 used when the value Tc of the control timer is equal to or less than the predetermined time Ct, θ ₂ increases as the value Tc of the control timer increases, so that the control timer The correction amount θ ₂ of the steering angle increases with time until the value Tc reaches the predetermined time Ct. Then, when the value Tc of the control timer reaches the predetermined time Ct, θ ₂ becomes CCθ, so that the target correction steering amount stored as the target control amount CCθ at this time is generated in the front wheels 8, 8. It will be.

When the value Tc of the control timer becomes longer than the predetermined time Ct, the process proceeds from step S26 to step S31, and the calculation formula of the steering angle correction value θ ₂ of the front wheels 8 and 8 is changed to the following formula for returning. The steering angle correction value θ ₂ is calculated based on this equation. θ ₂ = CCθ (2-Tc / Ct)

After step S31, step S
In 32, it is determined whether the stored value in the lateral G memory is rightward (corresponding to a left turn) or leftward (corresponding to a right turn). If the value is rightward, the process proceeds to step S33, where θ ₂ is returned to the return side. Solenoid part 95a of the electromagnetic switching valve 95
If it is leftward, the process proceeds to step S34, and the solenoid portion 95a of the electromagnetic switching valve 95 is controlled so that the return side becomes θ ₂ .

After step S33 or step S34 has passed, in step S35 the current corrected steering amount θ ₂
Is determined to be "0", and if not "0", the process returns to step S2. Then, through steps S6 to S26, the process reaches step 31 again.

In the arithmetic expression of step S31, when the value Tc of the control timer increases, θ ₂ decreases. Therefore, until the value Tc of the control timer reaches twice the predetermined time Ct (2Ct), the steering angle changes with time. The correction amount of is reduced. Then, when the value Tc of the control timer becomes 2 Ct, the correction steering amount θ ₂ calculated in step S31 becomes “0”, so that the correction steering angle for the front wheels 8, 8 of the minute steering angle mechanism 70 is not performed.

Then, from step S35 to step S3
When proceeding to 6, the control amount CCθ, the correction flag RFLG and the lateral G memory Myg are reset to “0”. After the lapse of step S36, the processing from step S2 is repeated again.

If the driver cuts the steering wheel 18 in the opposite direction following the return of the steering wheel 18, the process proceeds from step S5 to steps S8, 9 and 10 to prepare for the next return. , Then step S
Since the process proceeds to step 6, the processing after step S20 is performed as long as the correction flag RFLG is "1", and the correction flag RFLG is set.
Correction steering is executed until LG becomes "0".

At this time, since the preparation for the correction steering at the time of the next return is made during this execution, the correction steering at the time of the return is always performed even if the steering operation is continuously repeated. Become.

That is, according to the process for correcting the steering angle,
As shown in FIG. 13, the actual steering angles of the front wheels 8 and 8 are, when the steering wheel 18 is turned back at the reference steering angular velocity or higher, within a predetermined time 2Ct from the time when the rate of change of the lateral G becomes equal to or higher than a set value. The steering angle θH input from the steering wheel 18 is controlled by adding the minute steering angle (θ ₂ ) input from the minute steering angle mechanism 70.

When such steering angle correction is performed, the cornering force CF of the front wheels 8 increases as shown in FIGS. 14 and 15, and the cornering forces CF of the rear wheels 8a (shown only in FIG. 15) are balanced. Therefore, it is possible to avoid a phenomenon in which the cornering force of the front wheels 8 becomes extremely smaller than the cornering force of the rear wheels 8a when returning from the turning state to the straight traveling state. This means that the front wheels 8 are slightly steered in the direction in which the disturbance is corrected to avoid the influence of the disturbance. In other words, the convergence of the yaw trait is improved, and stable straight traveling is restored even during sudden steering. Moreover, the handle 18
During the steering operation, the control is appropriately controlled by the process of step S40 described above, so that high steering stability is always maintained.

Therefore, the integrated control of the appropriate control of the assist force of the power steering device and the control of the appropriate steering angle correction according to the steering angle situation can be performed, and the straight-line stability and steering stability of the vehicle can be greatly improved. Bring about an improvement in sex.

In the above-described embodiment, the plungers are arranged on both sides of the plate-shaped overhanging portion, and the fine rudder angle mechanism having the structure in which the overhanging portion is pressed by the plunger is used. However, the present invention is not limited to this. A fine rudder angle mechanism having the structure of, for example, a plurality of first claw portions is provided on the input shaft, and a plurality of second claw portions that are alternately arranged with the first claw portion are provided on the intermediate shaft, and between the two claw portions. A fine rudder angle mechanism having a structure in which a plunger is arranged and a claw portion is pressed by the plunger, or a fine rudder angle mechanism having a structure in which a ring gear of a planetary gear device is rotated by a pinion gear may be used.

Further, in the embodiment, as the avoidance of the influence of the disturbance, the control for improving the swing-back at the time of the return at the time of the sudden steering is shown as an example, but the control is not limited to this, and the disturbance of the steering due to the road surface condition is avoided. Alternatively, the control for avoiding the disturbance of the steering due to the influence of the side wind may be used.

[0093]

As described above, according to the present invention,
By the first control means and the second control means, it is possible to perform integrated control of appropriate control of the assist force and control of appropriate steering angle correction according to the steering angle situation. As a result, it is possible to significantly improve the straight running stability and steering stability of the vehicle.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a vehicle power steering apparatus according to an embodiment of the present invention together with a control system.

FIG. 2 is a sectional view showing the configuration of a steering mechanism in FIG.

FIG. 3 is a sectional view of the minute steering angle mechanism taken along the line AA in FIG.

FIG. 4 is a sectional view of the minute steering angle mechanism taken along line BB in FIG.

5 is a cross-sectional view of the minute steering angle mechanism taken along the line C-C in FIG.

FIG. 6 is a cross-sectional view showing a state in which the intermediate shaft is rotated to the right (small steering angle) with respect to the input shaft by the small steering angle mechanism.

FIG. 7 is a sectional view showing a state in which the intermediate shaft is rotated to the left (small steering angle) with respect to the input shaft by the small steering angle mechanism.

FIG. 8 is a flowchart showing the content of integrated control of assist force and steering angle correction at the time of return during sudden steering.

9 is a flowchart showing the contents of a reaction force control routine in FIG.

FIG. 10 is a diagram showing a control current value of a solenoid with respect to a vehicle speed for controlling an assist force.

FIG. 11 is a diagram for obtaining a control level.

FIG. 12 is a diagram showing a reference steering angular velocity corresponding to a vehicle speed.

FIG. 13 is a view showing the timing of correction operation control at the time of returning.

14 is a diagram showing the characteristics of yaw rate at the timing of FIG.

FIG. 15 is a diagram showing the characteristics of this yaw rate with a two-wheel model.

[Explanation of symbols]

1 ... Steering mechanism, 2 ... Steering gear (first steering angle mechanism), 7, 30, 46, 47 ... Power cylinder device, rotary valve, oil pump, reservoir tank (hydraulic assist mechanism), 8 ... Front wheel (steering wheel) ), 20 ... Reaction force mechanism (control means), 50 ... Pressure control valve (control means), 70 ... Micro rudder angle mechanism (second rudder angle mechanism), 100 ... Controller, 101
... lateral G sensor, 102 ... vehicle speed sensor, 103 ... steering angle sensor, 104 ... steering angular velocity sensor.

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location B62D 117: 00 137: 00 (72) Inventor Takeo Takeo 5-3-8 Shiba 5-chome, Minato-ku, Tokyo Mitsubishi Motors Corporation Incorporated (72) Inventor Tadao Tanaka 5-33-8, Shiba, Minato-ku, Tokyo Within Mitsubishi Motors Corporation

Claims (1)

[Claims] 1. A first steering angle mechanism for steering a steered wheel according to a steering operation from a steering wheel, and a hydraulic assist mechanism provided in the first steering angle mechanism for hydraulically assisting steering of the steered wheel. Control means provided in the hydraulic assist mechanism for varying the assist force generated by the hydraulic assist mechanism, first control means for controlling the control means in accordance with a steering state, and provided in the first steering angle mechanism A second steering angle mechanism for steering the steered wheels independently of the first steering angle mechanism, and setting means for setting a corrected steering angle value according to the situation during the steering operation, A power steering apparatus for a vehicle, comprising: second control means for controlling the second steering angle mechanism according to the corrected steering angle value of the setting means.