JPS61200065A - Controller for car - Google Patents

Abstract

PURPOSE:To improve the traveling stability by calculating each steering amount of rear wheels for that of front wheels on the basis of each load of front and rear wheels and car speed. CONSTITUTION:Load meters 12a and 12b are installed onto the right and left front wheels 6a and 6b, and load meters 13a and 13b are installed onto the right and left rear wheels 7a and 7b. Each output signal of these load meters 12a, 12b, 13a and 13b are input into a control circuit 11. A steering-angle detector 10 is installed onto a front-wheel steering machine 9, and also the output signal of the detector 10 is input into the control circuit 11. The control circuit 11 calculates each steering amount of the rear wheels 7a and 7b for each steering amount of the front wheels 6a and 6b on the basis of each output signal and car speed signal, and a rear-wheel steering machine 14 is controlled so that the calculated value is obtained. The control circuit 11 determines the proper distribution of brake power for the front and rear wheels, and a hydraulic distributor 16 is controlled so that the determined distribution of brake power can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a control device for a motor vehicle, and more particularly to a control device that can provide excellent running stability for a four-wheel drive or four-wheel steering motor vehicle.

[Background of the invention]

In recent years, demands for higher performance of automobiles have been increasing, and various new technologies have been proposed to meet these demands.

A four-wheel steering system was discussed as a means of achieving excellent maneuverability and stability in a document entitled "Improving Vehicle Dynamic Performance by Four-Axis Steering," which was published in the Society of Automotive Engineers of Japan Symposium Text (June 1980). Although the advantages of four-wheel steering are described based on the results of various experiments, this document does not describe any specific control means. In particular, no control device for four-wheel drive or four-wheel steering vehicles that can provide excellent running stability has been realized.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its purpose is to provide a control device for an automobile that has excellent driving performance and high safety.

[Summary of the invention]

The present invention provides a load meter for each front wheel and rear wheel of a four-wheel drive or four-wheel steering vehicle, inputs these detected values to a control device, and calculates the steering amount of the front wheels together with the detected vehicle speed input from the speedometer. This control device calculates the amount of steering of the rear wheels relative to the amount of steering required to achieve the intended purpose.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an automobile control device according to the present invention will be described below with reference to the drawings.

An embodiment of the present invention is shown in FIGS. 1 and 2. FIG.

In FIG. 1, the output of an engine 1 is transmitted to a center differential 3 via a transmission 2. One axle of this center differential 3 is connected to the front differential 4, and the other axle is connected to the rear differential 5.
The front differential 4 connects the left and right front wheels 6a, 6b, and the rear differential 5 connects the left and right rear wheels 7a, 6b.
7b, respectively. The left and right front wheels 6a.

6b is steered via a front wheel steering device 9 according to the turning angle of the steering wheel 8, and this steering amount is detected by a steering angle detector 10 and input to a control circuit 11. the left and right front wheels 6a;
6b each has a load cell 12a.

12b is a load cell 1 on each of the left and right rear wheels 7a and 7b.
3a and 13b are attached, and these load cells 1
The loads detected by 2a, 12b, 13a, 13b are input to the control bag [11.

This four-way brake circuit 11 controls the rear wheel 7 based on the steering amount detected by the steering amount detector 10, the load detected by each of the load meters, and the vehicle speed detected by a speedometer (not shown).
The steering is performed by calculating the amount of steering of the rear wheel steering device 14 that steers the wheels a and 7b. Further, when the driver depresses the brake pedal 15, the hydraulic distributor 16 is activated in response to an instruction from the control circuit 11, as in the case of rear wheel steering described above, and the front wheels 6a
, 6b and rear wheels 7a, 7b, respectively. As shown in FIG. 2, this hydraulic pressure distributor 16 sends hydraulic pressure to the hydraulic pressure distributor 16 when the brake pedal 15 is depressed, and when the detection signal of the load received by the control device 11 is larger for the rear wheel, for example. A current flows in the direction shown by the arrow in the coil 17 provided in this hydraulic distribution 1116,
A plunger 18 provided on the inner diameter of the coil 17 moves rightward in the figure against the biasing force of the spring 19a, and the orifice 20 provided at the hydraulic outlet of the hydraulic distributor 16 moves to the right in the figure.
Among the rear wheels 7a and 20b, the orifice 20a of the hydraulic outlet connected to the brakes of the front wheels 6a and 6b is narrowed, and the opening degree of the orifice 20b of the hydraulic outlet connected to the rear wheels 7a and 7b is increased.

It is designed to increase the control force by increasing the oil pressure to 7b more quickly. When the load on the front wheels 6a, 6b is large, on the other hand, the plunger 18 moves to the left in the figure against the biasing force of the spring 19b, thereby increasing the braking force on the front wheels 6a, 6b.

The operation of this embodiment configured as described above will be explained below. The steering amount of the front wheels 6a and 6b is δ1, and the rear wheel 7a is
, 7b is the steering amount δ2, and the vehicle speed is V (km/h), the relationship between δ2/δ□ and V is shown in FIG. When the loads on the front and rear wheels are P and P2, respectively, p
When z/p 1=1, v= as shown by the solid line
0, that is, when stopped, δ2/δ1 = approximately -0,8
It is. This means that by steering the front and rear wheels in opposite phases, the turning radius becomes smaller and the inner axle difference can be eliminated. As the vehicle speed V increases, the steering ratio δ2/δ1 becomes close to 0, and only the front wheels 6a and 6b are steered at ■=approximately 40 km/h.

If the speed is higher than this, the steering will be in phase, and V = 1100
At k/h, δ2/δ=approximately 0.5. At high speeds, steering in the same phase improves driving stability.

On the other hand, the load P1 applied to the front wheels 6a and 6b and the rear wheel 7a.

When the load P2 applied to the tire 7b changes, the driving force of the tire also changes. Therefore, when climbing a board or when there are many passengers at the rear, that is, when p2>pl, the cornering force of the rear wheels increases, so the actual steering angle of the rear wheels increases at the same steering ratio. Therefore, when P, /P1>1, the high-speed steering ratio is set to δ'2/δ1<0, as shown by the dashed line.
5, P2/P in the opposite case, δ as shown by the dotted line in the case of <1, and /δ□>0.5, thereby increasing high-speed running stability.

FIG. 3 shows the relationship between the tire drive torque T and the slip rate S in terms of loads p, , p2. If the load is large, the driving force will also increase. In the case of four-wheel drive, its true value is demonstrated only when the coefficient of friction between the road surface and the tires is small, but if there is a difference in the load between the front and rear wheels, a difference will occur in the drive torque depending on each load. do. However, in the case of a center differential type, as shown in Figure 3, the loads P1 and P2 applied to the front and rear wheels are
If there is a difference between the two, it will not be possible to drive the front wheels with more than twice the driving force of the rear wheels, which have a smaller load. In this manner, when the loads on the front wheels and the rear wheels exceed a set value, a locking device (not shown) of the center differential 3 is activated, thereby making it possible to effectively utilize the driving torque.

On the other hand, the driving torque of the tires is almost the same as the braking force when the brakes are applied. Therefore, if there is a load difference between the front wheels and the rear wheels, the braking forces between the front wheels and the rear wheels will naturally also differ.

When an anti-skid system detects axle slip, the axle with the least load begins to slip earlier, so the brakes are weakened. Therefore, the axle, which has a large load and can produce a large braking force, cannot utilize sufficient braking force. To solve this problem, a hydraulic distributor 16 as shown in FIG. 2 is used to adjust and supply brake hydraulic pressure according to the load ratio of the front and rear wheels.
This allows maximum use of the braking force of the front and rear wheels.

As described above, according to this embodiment, when driving at low speeds, the front and rear wheels are steered in opposite phases, when driving at approximately 40 km/h, only the front wheels are steered, and when driving at high speeds, the wheels are steered in the same phase to improve driving stability. can do. In addition, the steering ratio is changed according to changes in the loads applied to the front and rear axles, and the braking force applied to the front and rear wheels is adjusted, so that the braking force can be effectively transmitted to each wheel.

〔Effect of the invention〕

As described above, according to the present invention, the load on each wheel of a four-wheel drive or four-wheel steering vehicle is detected, and the steering ratio and braking force of the front and rear wheels are changed by the control device. Therefore, braking time is shortened and excellent running stability can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of a control device for an automobile according to the present invention, Fig. 2 is a detailed block diagram showing the hydraulic distributor of Fig. 1, and Fig. 3 is a diagram showing the relationship between vehicle speed and steering ratio. The graph shown in FIG. 4 is a graph showing the relationship between slip rate and drive torque. 1... Engine, 6a, 6b... Front axle, 7a, 7b
...Rear wheel, 8...Handlebar, 9...Front wheel steering device,
1o... Steering angle detector, 11... Control circuit, 12a
, 12b. 13a, 13b...Load cell, 14...Rear wheel steering device,
Figure 1 A ratio Figure 3 Vehicle speed V (Kn/h) Figure 4 P. Surimu S

Claims (1)

[Scope of Claims] 1. A control device for an automobile comprising a transmission mechanism that transmits the driving force of an engine to front wheels and rear wheels, and a steering device that transmits a steering angle of a steering wheel to the wheels and the rear wheels. A control device for an automobile, characterized in that the steering ratio of the front wheels and the rear wheels is changed depending on the vehicle speed of the automobile and the loading ratio applied to the front wheels and the rear wheels. 2. The control device for an automobile according to claim 1, wherein the braking force applied to the front wheels and the rear wheels is changed depending on the load ratio of the front wheels and the rear wheels, respectively.