JPH05319123A - Front and rear wheel driving torque distribution control device for four-wheel drive vehicle - Google Patents

Abstract

PURPOSE:To provide a front and rear wheel driving torque distribution control device of a four-wheel drive vehicle of which the steering angle of a constant speed joint can be set large and the small sharp turning ability can be insured. CONSTITUTION:The steering angle of front wheels 10 is detected by means of a steering angle sensor 13, when the steering angle exceeds a decided value driving torque distribution rate for the front wheel 10 is gradually decreased by a torque limiting means 14, and input of large driving torque to the front wheels is prevented by slipping of a wet type multiple disk clutch 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a four-wheel drive vehicle, and more particularly to a full-time four-wheel drive vehicle. The present invention relates to a distribution control device.

[0002]

2. Description of the Related Art Conventionally, as a front / rear wheel drive torque distribution control device for such a four-wheel drive vehicle, for example, JP-A-62-27 is known.
The one described in Japanese Patent No. 5836 is known.

This vehicle is equipped with a control system that distributes the driving torque of the front and rear wheels depending on the running state, and runs in urban areas, mountain roads, suburbs, depending on running conditions for a predetermined time obtained from the average values of vehicle speed and steering angle. A plurality of traveling modes such as high-speed traveling are discriminated and the driving torque distribution of the front and rear wheels is controlled for each of the various traveling modes.

[0004]

However, in such a front-rear wheel drive torque distribution control device for a conventional four-wheel drive vehicle, since the control corresponding to the steering angle is not performed in real time, the large steering is performed. Even in the corner state, the drive torque distribution to the front wheels may increase. For example, there is a case where the vehicle is accelerating from a low speed while maintaining a large steering angle in the city driving mode.

When such a phenomenon occurs, the use condition of the constant velocity joint for transmitting the driving torque to the front wheels may be severe, and therefore the cutting angle of the front wheels (constant velocity joint) is usually set small. I don't get it. As a result, there is a problem that the four-wheel (front wheel) drive vehicle has poor turning performance as compared with the rear-wheel drive vehicle.

In view of the above facts, an object of the present invention is to provide a front / rear wheel drive torque distribution control device for a four-wheel drive vehicle capable of setting a large turning angle of a constant velocity joint and ensuring a small turning ability. ..

[0007]

In order to achieve the above object, the present invention controls the front / rear wheel drive torque distribution control device for controlling the front / rear wheel drive torque distribution according to the running state of the vehicle. In, a steering angle detecting means for detecting the steering angle of the front wheels, and a torque limiting means for limiting the front wheel drive torque by gradually reducing the drive torque distribution ratio to the front wheels when the steering angle by the steering angle detecting means exceeds a predetermined value. It is characterized by having and.

[0008]

According to the present invention, the steering angle of the front wheels is detected by the steering angle detecting means. When the steering angle exceeds a predetermined value, the torque limiting means gradually reduces the distribution ratio of the driving torque to the front wheels. Therefore, when the steering angle exceeds the predetermined value, a large driving torque is not input to the front wheels, so that the turning angle of the constant velocity joint can be set large.

[0009]

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

In FIG. 1, 1 is an engine, 2 is a transmission, 3 is a transfer, and an output shaft 2A of the transmission 2 is connected to a rear differential device 5 through a center drive shaft 3A and a propeller shaft 4 of the transfer 3 in sequence. There is. Transfer 3
Center drive shaft 3A and the shaft 3A
A wet multi-plate clutch 6 that connects and disconnects with a drive sprocket 3B that is rotatably provided above is provided, and the wet multi-plate clutch 6 is driven by a hydraulic actuator 7. Inside the transfer 3, a driven sprocket 3D driven by a driving sprocket 3B via a silent chain 3C is further provided, and is connected to a front differential device 9 via a front drive shaft 8.

Numeral 10 is a wheel, and a wheel rotation sensor 11 (11 ₁ , 11 ₂ , 11) for detecting the number of rotations (R ₁ , R ₂ , R ₃ , R ₄ ) of the wheel 10 corresponding to each wheel.
₃ , 11, ₄ ) are provided. 12 is

[0012]

[Outer 1]

A throttle opening sensor for detecting G, an acceleration sensor (hereinafter referred to as a G sensor) G for detecting accelerations (G ₁ , G ₂ ) in the longitudinal and lateral directions of the vehicle, and a steering angle (θ) 13 for the front wheels. Is a steering rudder angle sensor that detects the signal. Detection signals from these sensors 11, 12, G and 13 are input to a control unit 14 including a microcomputer or the like.

Reference numeral 15 denotes a hydraulic unit, which is provided with a pump 15A as a hydraulic pressure source and a proportional electromagnetic pressure-reducing control valve 15B which is a control valve for controlling the discharge pressure of the pump 15A to reduce the pressure. A control current is supplied from the control unit 14 to the proportional electromagnetic pressure-reducing control valve, and a pressure corresponding to the current value exerts on the actuator 7.

In this embodiment having the above-mentioned structure, the torque of the engine 1 output through the transmission 2 is the center drive shaft 3 in the transfer 3.
The rear wheel 10 is driven via the A, the propeller shaft 4, and the rear differential device 5. With respect to the torque for driving the front wheels, the wet multi-plate clutch 6 is engaged by moving the actuator 7 by the command hydraulic pressure from the hydraulic unit 15, and as a result, the sprocket 3 on the center drive shaft 3A is engaged.
B is transmitted to B and the front wheel 10 is rotated by the silent chain 3C via the front wheel sprocket 3D, the front drive shaft 8 and the front differential device 9. The amount of torque transmitted to the front wheels depends on the wet multi-plate clutch 6
It changes when the pressing load of is controlled. That is, in the discontinuous state of the wet multi-plate clutch 6, only the rear wheels are driven, and the drive torque distribution ratio to the front wheels is 0% (front: rear distribution ratio = 0: 100). On the contrary, when the wet multi-plate clutch 6 is in the completely connected state without slipping, the front and rear wheels are evenly driven, and the drive torque distribution ratio to the front wheels is 100% (front: rear distribution ratio = 50: 50).

An example of actual control will be described with reference to the flow charts shown in FIGS.

In FIG. 2, when control is started, a detection signal is read from the sensor in step S1. That is, the rotational speeds R _{1 to} R _{4 of} each wheel 10, the longitudinal and lateral accelerations G ₁ and G ₂ , and

[0018]

[Outside 2]

[0019] Then, in step S2, the front wheel transmission torque T _F1 is calculated using the detection signal as a parameter. Further, the process proceeds to step S3, and the front wheel torque limiting subroutine is executed.

In this front wheel torque limiting subroutine, in step S31, the steering steering angle sensor 1
The steering angle θ by 3 and the above-mentioned front wheel transmission torque T _F1 are read. Next, in step S32, it is determined whether or not the absolute value of the steering angle | θ | exceeds a predetermined value θ _0. If not, the process proceeds to step S35. When it exceeds the predetermined value θ ₀ , the routine proceeds to step S33, where the front wheel transmission torque T _F1 is determined corresponding to the steering angle θ as shown in FIG.

[0021]

[Outside 3]

It is judged whether or not it exceeds. If it does not exceed here, the process proceeds to step S35, and if it does, the process proceeds to step S34.

Therefore, in step S34, the front wheel transmission torque T _F1 corresponds to the drive torque distribution ratio to the front wheels which is gradually decreased beyond the predetermined value θ as described above.

[0024]

[Outside 4]

Is replaced by As a result, the control current from the control unit 14 is applied to the wet multi-plate clutch 6
The actuator 7 is output so as to generate a pressing force enough to cause the actuator 7 to slide. That is, the steering angle θ is a predetermined value θ
The driving torque distribution ratio to the front wheels becomes smaller as it exceeds ₀ and finally becomes 0%. At this time, the front wheels 1
The drive torque of 0 becomes 0.

On the other hand, in step S35, the front wheel transmission torque T obtained in step S2 is obtained without limiting the torque.
_A control current is sent to the hydraulic unit 15 to obtain _F1 .

[0027]

As is apparent from the above description, according to the present invention, steering angle detecting means for detecting the steering angle of the front wheels,
When the steering angle by the steering angle detecting means exceeds a predetermined value, the torque limiting means for gradually reducing the drive torque distribution ratio to the front wheels to limit the front wheel drive torque is provided.
When the steering angle is large, a large driving torque is not input to the front wheels, and the turning angle of the constant velocity joint can be set to a large extent accordingly. Therefore, a small turning property can be secured.

[Brief description of drawings]

FIG. 1 is a system configuration diagram showing an outline of the present invention.

FIG. 2 is a flowchart for explaining an example of a control procedure of the present invention.

FIG. 3 is a flowchart for explaining an example of a control procedure of the present invention.

[Fig. 4] Steering angle θ

[Outside 5] It is a characteristic graph which shows an example.

[Explanation of symbols]

 3 Transfer 6 Wet multi-plate clutch 7 Actuator 11 Wheel rotation sensor G Acceleration sensor 13 Steering angle sensor 14 Control unit 15 Hydraulic unit

Claims (1)

[Claims] 1. A front / rear wheel drive torque distribution control device for a four-wheel drive vehicle, wherein a front / rear wheel drive torque distribution control device controls a front / rear wheel drive torque distribution according to a running state of the vehicle, and steering angle detection means for detecting a front wheel steering angle, A front and rear of a four-wheel drive vehicle, comprising: torque limiting means for gradually reducing the drive torque distribution ratio to the front wheels when the steering angle by the steering angle detecting means exceeds a predetermined value to limit the front wheel drive torque. Wheel drive torque distribution control device.