JPS6364881A - Discriminating device for condition of road surface - Google Patents

Abstract

PURPOSE:To improve the stability of running, by detecting a handle steering angle, speed of a vehicle and repulsive force of handle control while correcting a steering amount of a wheel in accordance with the information of the detected car speed and repulsive force and performing the actual steering action by the corrected steering amount. CONSTITUTION:A wheel steering amount arithmetic part 110 obtains a steering amount from a handle control amount of a steering angle sensor 100 and a vehicle running speed of a car speed sensor 101, while a correction amount arithmetic part 120 calculates a correction amount in accordance with detection amounts from a car speed sensor 101 and a distortion sensor 102, which detects repulsive force of handle control, and the wheel steering amount arithmetic part 110, which corrects the obtained steering amount in accordance with the correction amount from the correction amount arithmetic part 120, outputs a steering amount, finishing the correction, to a motor driving part 130 for steering a wheel. Accordingly, in addition to determination of the steering amount by a steering angle amount of the handle control and the car speed, the steering amount is corrected by the repulsive force for a handle, when it performs a steering control between the handle and a tire, thus the stability of running can be very high increased by enabling the steering to correspond to a road condition.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention steers the front wheels in response to steering wheel operation, steers the rear wheels in response to the steering of the front wheels, and steers the front wheels in accordance with the driving condition. The present invention relates to a road surface condition determination device for a vehicle having a four-wheel steering device capable of controlling the steering ratio of rear wheels.

(Prior Art) In recent years, automobiles have been provided that are equipped with a four-wheel steering system that steers both the front wheels and the rear wheels. Among these, as shown in Japanese Patent Application Laid-Open No. 60-135369, a system has been proposed in which the steering ratio characteristic can be changed by manual operation. The present invention has a function of gradually changing and shifting over time from a rudder state to a steered state after switching, thereby eliminating the need for unnecessary efforts to correct the steering wheel even if the switching means is operated while driving and turning.

(Problem to be solved by the invention) Since the steering ratio characteristics are uniformly changed by this manual operation, for example, on a low μ road, increasing the steering angle of the rear wheels in the same phase direction will improve stability. Although it is known that μ increases significantly, there has been no method to detect such μ until now, and it has not been possible to adequately cope with it.

(Means for Solving the Problems) The present invention has been made in view of the above-mentioned problems, and as a means for eliminating the above-mentioned problems, the present embodiment has the following configuration.

That is, a steering angle detection means for detecting the steering wheel angle, a vehicle speed detection means for detecting the speed of the vehicle, a detection means for detecting a repulsive force in response to a steering wheel operation, which is disposed between the steering wheel and the tire, and A correction means is provided for correcting the steering amount of the wheels according to the detected repulsive force information and the vehicle speed detected by the vehicle speed detection means.

(Function) In the above configuration, the detection means detects the repulsive force (distortion with respect to the steering wheel input) information in the steering operation between the steering wheel and the tires detected by the detection means and the vehicle speed detection means with respect to the steering amount according to the steering wheel steering angle. The system makes corrections based on the vehicle speed, contributing to improved driving stability.

(Example) Hereinafter, an example according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a functional block diagram of an embodiment according to the present invention. In the figure, 100 is a steering angle sensor that detects the amount of steering angle of the steering wheel; 101 is a vehicle speed sensor that detects the running speed of the vehicle;
2 is a strain sensor that detects the repulsive force from the tires in response to the steering wheel operation; 110 is the steering angle sensor 10;
The steering amount obtained from the steering wheel operation amount of 0 and the vehicle running speed from the vehicle speed sensor 101 is corrected according to the correction amount from the correction amount calculation unit 120, and the corrected steering amount is used for wheel steering. a wheel turning amount calculation unit that outputs to the motor drive unit 130;
120 is a correction amount calculation unit that calculates a correction amount for the wheel turning amount according to the detection amount from the vehicle speed sensor 101 and the strain sensor 102; 140 is a motor rotation angle sensor that detects the rotation angle of the motor 150 and outputs it to the motor drive unit 130. 150 is a motor that steers the wheels.

In this embodiment, by providing the above-mentioned functions, in addition to determining the steering amount based on the steering angle amount of the steering wheel operation and the vehicle speed, the steering amount is determined by the repulsive force against the steering wheel that is generated during steering operation between the steering wheel and the tires. The steering amount can be corrected to correspond to the μ from the road, and driving stability can be greatly increased.

Next, FIG. 2 shows an overall system diagram of a vehicle equipped with a control unit having the above-mentioned functions according to this embodiment, for example, a front-wheel drive vehicle (FF vehicle).

In Fig. 2, IR is the right front wheel, IL is the left front wheel, 2R is the right rear wheel, and 2L is the left rear wheel.The left and right front wheels IR and IL are linked by a front wheel steering mechanism A, and the left and right rear wheels are 2R,
2L is linked by rear wheel steering mechanism B.

In the embodiment, the front wheel steering mechanism A includes a pair of left and right knuckle arms 3R, 3L and tie rods 4R, 4L, and a pair of left and right tie rods 4R.

It is composed of a relay rod 5 that connects the 4Ls. A steering mechanism C is linked to the front wheel steering mechanism A, and the steering mechanism C is of a rack and pinion type. That is, a rack 6 is formed on the relay rod 5, and a pinion 7 that meshes with the rack 6 is connected to a handle 9 via a shaft 8 on which a strain sensor 102 is disposed. This allows the handle 9
When the relay rod S is displaced to the left in FIG. 1, the knuckle arms 3R, 3L operate the handle 9 about their rotation centers 3R', 3L'. The vehicle is steered clockwise in the figure by an amount corresponding to the amount of displacement, that is, the steering angle of the steering wheel. Similarly, when the steering wheel 9 is turned to the left, the left and right front wheels IR will change depending on the amount of displacement of this operation.

IL will be steered to the left. At this time, the repulsive force (operation torque amount) against the handle operation is detected by the strain sensor 102.

Similarly to the front wheel steering mechanism A, the rear wheel steering mechanism B also has a pair of left and right knuckle arms IOR, IOL and tie rods IIR, IIL, and a relay rod 12 that connects the tie rods IIR, IIL. Rudder mechanism B
is equipped with a hydraulic power mechanism (boosting mechanism) D.

To explain this power mechanism, the relay rod 1
2 is attached with a cylinder device 13, and the cylinder 1
A piston 13d that defines the interior of 3a into two chambers 13b and 13c.
is integrated into the relay rod 12. The two chambers 13b and 13c within this cylinder 13a are connected to the piping 14 or 1
5 to a control valve 16.

Further, each of the control valves 16 is connected to pipes 18 and 19 extending from the reservoir tank 17, and an oil pump 20 driven by a control unit 61 is connected to one of the pipes 18, which serves as an oil supply pipe. A rack 22 is formed on the relay rod 12, and a pinion 21 is engaged with the rack 22. A bevel gear 91 is fixed to the drive shaft 21a of the binion 21 via a control valve 16, and the binion 21 is driven by a pulse motor 150 via a pair of bevel gears 91 and 92. And this motor 15
Drive control of 0 is performed by a control unit 61.

In addition to the signal from the strain sensor 102, the control unit 61 receives a signal from the front wheel steering angle detection sensor 100, and further receives a signal from the vehicle speed sensor 101 as necessary. . In such a power mechanism, as is known, when the drive shaft 21a of the binion 21 is rotated in one predetermined direction, the binion 21 is rotated in the same direction in response to this, and the relay rod 1
For example, the knuckle arms IOR, IOL are displaced to the left in FIG.
The rear wheels 2R and 2L are turned to the right by rotating clockwise in FIG. 2 about OL'. And during this turning,
Oil is supplied into the chamber 13b of the cylinder device 13 according to the amount of rotation of the drive shaft 21a, and the relay rod 12
(boosting effect), similarly, drive! !
When the II glaze 21a is rotated in the opposite direction, the rear wheels 2R and 2L move to the left while receiving the boosting action of the cylinder device 13 (oil is supplied to the chamber 13b) according to the amount of rotation. It will be steered.

In addition, 13e and 13f in FIG. 2 are return springs that urge the relay rod 12 to the neutral position.
59 is a battery.

A detailed diagram of the steering mechanism C is shown in FIG.

In the embodiment, a shaft 8 connected to a handle 9 is connected to a pin-on 7 via an intermediate shaft 8a. A strain sensor 102 is incorporated in the shaft 8, and detects the return force (applied to the shaft) to detect μ between the tire and the road surface.

The details of this strain sensor 102 are shown in FIG. 4(A).

Shown in (B). FIG. 4(B) is a sectional view taken along the line AA in FIG. 4(A).

As shown in the figure, the handle side shaft 8a and the nion side shaft 8a are linked in the handle rotation direction, and a strain sensor 102 is held in the joint part, and an electric signal is sent to detect the repulsive force (load amount) on the pinion side against the handle rotation. is being converted to . This strain sensor 102 can be composed of, for example, an St bar.

Also, by changing the above configuration, connecting the handle side shaft 8a and pinion side shaft 8b with a torsion bar or the like,
The repulsive force (load amount) may be detected by measuring the displacement between both shafts.

The rear wheel steering control of this embodiment having the above configurations will be described below with reference to the flowchart of FIG. 5.

These controls are carried out by a wheel turning amount calculating section 110 and a correction amount calculating section 120 shown in FIG. 1 of the control unit 61.
This is done by

First, in step S1, the wheel turning amount calculating section 110 and the correction amount calculating section 120 calculate the steering angle amount (θ, ) from the steering angle sensor 100.
The wheel turning amount calculation unit 110 reads the following step S.
2, the current vehicle speed (V) is read from the vehicle speed sensor 101. Then, in step S3, the rear wheel turning amount is calculated and determined from the steering angle θ and the vehicle speed ■. The steering amount characteristic determined here is, for example, as shown by the solid line A in Fig. 6, and when the vehicle speed V is slow, the steering is performed in the opposite phase to the front wheels, assuming that the steering wheel operation is intended to rotate (sudden turn). However, it improves rotational performance, and when the vehicle speed becomes faster, it steers in the same phase direction as the front wheels, providing control that allows for smooth lane changes.

Next, the correction amount calculation unit 120 pays attention to the fact that stability is greatly improved by increasing the turning angle of the rear wheels in the same phase direction on a low μ road, and in step S4, the distortion data (α
Note that the relationship between μ from the road surface and strain is proportional as shown in FIG. In the following step S5, the vehicle speed V is read from the vehicle speed sensor 101. The road surface μ varies depending on the vehicle speed (2), and the higher the vehicle speed V, the weaker the tire's grip on the road surface, and the smaller the amount of strain detected by the strain sensor 102. The relationship between the vehicle speed V and the steering force (distortion) αμ is shown in Fig. 348. The correction amount calculation unit 120 calculates the road surface μ from the read vehicle speed ■ and the distortion αμ, and calculates the correction amount for the rear wheel turning amount previously calculated by the rear wheel turning amount calculation unit 110. This correction amount becomes larger as the road is lower in resistance that the tire receives from the road surface, and becomes, for example, the correction amount shown in FIG. 9. In this way, the correction amount performance nose part 12
The correction amount obtained at 0 is sent to the wheel turning amount calculation section 110,
The wheel turning amount calculation unit 110 corrects the steering amount previously obtained in step S3, and calculates the actual wheel turning amount. This example is shown by dashed line B in FIG.

Instead of performing each of the above calculations, an output turntable for these constant inputs is stored in memory, and control is performed so that the steering amount and correction amount corresponding to human power are gradually read out and output from the output turntable. You may.

Then, in step S8, the wheel turning amount calculating section 110 operates the motor driving section 1 according to the steering amount corrected in this way.
30, and the motor drive section 30 rotates the motor 150 in accordance with the drive signal to perform rear wheel steering. Note that the amount of rotation of the motor 150 is detected by a motor rotation angle sensor 140, which is, for example, a rotary encoder attached to the drive shaft of the motor 150, and this detected value is reported to the motor drive unit 130. Then, when the desired amount of steering is performed, the process ends.

In this way, when the μ from the road surface is small, the turning angle is increased, and when the amount of distortion is large and the μ from the road surface is large, the correction amount is reduced to reduce the turning angle, resulting in extremely high running stability. Four-wheel steering is possible.

In addition, in vehicles such as PR cars and RR cars that drive the rear wheels 2R and 2L, the rear wheels 2R and 2L are driven by the front wheels
What is necessary is to correct R and IL more toward the same phase side.

As explained above, according to this embodiment, the steering ratio is adjusted to an optimum ratio based on the road surface μ and the front wheel steering angle θ, compared to the conventional method of steering the rear wheels using a fixed steering ratio. It can be controlled automatically and can improve driving stability.

(Effects of the Invention) As explained above, according to the present invention, it is possible to realize a road surface condition determination device that can provide an automobile with extremely high running stability.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a steering control section according to an embodiment of the present invention, Fig. 2 is an overall system diagram of this embodiment, Fig. 3 is a detailed diagram of the steering mechanism, Fig. 4 (A), ( B) is a detailed diagram of the strain sensor, FIG. 5 is a flowchart of the rear wheel steering control of this embodiment, and FIGS. 6 to 9 are characteristic diagrams showing an example of changing the steering ratio. In the figure, A...front wheel steering mechanism, B...rear wheel steering mechanism,
C...Steering mechanism, E...Steering ratio changing device,
IR, IL...Front wheel, 2R, 2L...Rear wheel, 8...
- Shaft, 9... Handle, 61... Control unit, 100... Rudder angle sensor, 101... Vehicle speed sensor, 102... Strain sensor, 110... Wheel turning amount calculation unit, 120 ...Correction amount calculation section, 130...
Motor ffi moving part, 150...Motor.

Claims (1)

[Claims] A vehicle with a four-wheel steering device that can steer the front wheels in response to steering wheel operation, steer the rear wheels in response to the steering of the front wheels, and control the steering ratio between the front and rear wheels depending on the driving condition. A road surface condition discriminating device in which a steering angle detection means detects a steering angle, a vehicle speed detection means detects the speed of a vehicle, and a detection device disposed between a steering wheel and a tire detects a repulsive force in response to a steering wheel operation. A road surface condition discriminating device comprising: a means for determining a road surface condition; and a correcting means for correcting the amount of wheel turning according to the repulsive force information detected by the detecting means and the vehicle speed detected by the vehicle speed detecting means.