JPS6299213A - Drive power distribution control device for four wheel drive vehicle - Google Patents

Abstract

PURPOSE:To make it possible to corner a vehicle at the driver's will, by computing an ideal yaw angle in accordance with the speed and steering angle of the vehicle so that the distribution of drive power for front and rear wheels is controlled to allow an actual yaw angle rate to coincide with an ideal yaw angle rate. CONSTITUTION:When sensors 15, 16 deliver a vehicle speed and a steering angle to a computing circuit 19 which therefore computes an ideal yaw angle rate phis that is delivered to a processing circuit 21, Meanwhile, a sensor 17 delivers a yaw angle to a detecting circuit 20 which computes an actual yaw angle rate phi that is delivered to the processing circuit 21. The processing circuit 21 compares both yaw angle rates phis, phi with each other and to delivers a signal to hydraulic control valves 13, 14 such that the difference between both yaw angle rates becomes zero. Thereby, the hydraulic pressures of front and rear clutches 4, 7 are controlled to increase and decrease the drive forces of front and rear wheels 6, 9, and therefore, an FR-like drive force distribution is obtained to correct a shift between both yaw angle rates. With this arrangement, it is possible to enhance the running ability and safety of the four wheel drive vehicle.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a driving force distribution control t2Il device that controls the driving force distribution between the front and rear wheels of a four-wheel drive vehicle, and more particularly to one that controls the driving force distribution based on the yaw angular velocity of the vehicle when turning.

[Conventional technology]

Conventionally, in a four-wheel drive vehicle, as shown in Japanese Unexamined Patent Application Publication No. 56-43031g, there have been methods to control the distribution of driving force between the front and rear wheels of a four-wheel drive vehicle. The other transmits power via a hydraulic clutch. It has also been proposed to control the oil pressure of a hydraulic clutch using line pressure of an automatic transmission.

[Problems to be solved by the invention]

By the way, in the configuration of the above-mentioned prior art, the front and rear wheels are directly connected by engagement of a hydraulic clutch, and the hydraulic pressure is lowered so that the hydraulic clutch can slip at low loads to prevent tight yawner braking phenomenon when turning. It is something to avoid. Therefore, although the direct-coupled 4WD distributes the driving force in a slightly biased manner, it has not reached the point where it actively distributes the driving force in a front-wheel drive or R-like manner to improve maneuverability. The mechanism is not perfect, and if there is a disturbance such as a puddle or ice patch during a turn, or if there is an operational error such as excessive acceleration or deceleration, the mechanism may try to deviate from the desired trajectory of the vehicle against the driver's will. In this case, change the drive force distribution between the front and rear wheels to
By doing so, the vehicle itself can correct the deviation in the vehicle motion trajectory. The present invention has been made in view of these points, and by changing the drive force distribution between the front and rear wheels, the vehicle itself actively corrects the movement of the vehicle that is contrary to the driver's will, thereby achieving the vehicle movement that is contrary to the driver's will. The object of the present invention is to provide a driving force distribution control device for a four-wheel drive vehicle that enables yawning.

[Means to solve the problem]

In order to achieve the above object, the present invention calculates an ideal yaw angular velocity based on vehicle speed and steering angle sensor signals, and distributes driving force between the front and rear wheels so that the actual yaw angular velocity measured by the yaw angle sensor matches the ideal yaw angular velocity. is configured to control.

[For production]

Based on the above configuration, when the vehicle attempts to move at a yaw angular velocity different from the ideal yaw angular velocity due to disturbance or the like during a turn, the driving force distribution between the front and rear wheels changes to correct the deviation in the yaw angular velocity. In this way, according to the present invention, when turning, it is possible to always perform yawning as intended by the driver at the ideal yaw angular velocity based on the vehicle speed and steering angle.

【Example】

Embodiments of the present invention will be described below based on the drawings. In FIG. 1, to explain the outline of the entire configuration, an engine 1 is transferred to a transfer Vt position 3 via a transmission @2.
Transmission is configured from the transfer device 3 to the front wheels 6 via a hydraulic front wheel clutch 4 and a front differential device 5, and simultaneously to the rear wheels 9 via a hydraulic rear wheel clutch 1 and a rear differential device 8. ing. A hydraulic circuit 11.12 from the oil pump 10 communicates with each clutch 4.7, and a hydraulic control valve 13.14 in the hydraulic circuit 11.12.
The driving force distribution between the front and rear wheels 6.9 is determined by the clutch oil pressure of each clutch 4.1. On the other hand, as an electric control system, a vehicle speed sensor 15 and a steering angle sensor 1
6 and a yaw angle sensor 17 using a gyro or the like. Signals from the vehicle speed sensor 15 and steering angle sensor 16 are input to an arithmetic circuit 19 of the control unit 18, and an ideal yaw angular velocity is calculated from the vehicle speed and steering angle values. As shown in Figure 2, the distance between the center of gravity G of the vehicle, the distance between the front and rear wheels 6.9 21 The distance from the center of gravity G to the front and rear wheels 11
11f, Ar, yI rear wheel yawning power Kf,
)(r, steering angle δ, and vehicle speed V, the ideal yaw angular speed φS is found by the following formula. φs=[1/(1−(g+/21)x (Af Kr −Ar Kr ) X V2 /Kf Kr ] ×(V/A)X
δ Also, the signal from the yaw angle sensor 17 is input to the detection circuit 20 to detect the actual yaw angular velocity φ, and the processing circuit 21 compares the two yaw angular velocities φS and φ, and adjusts the hydraulic pressure so that the difference becomes zero. It is configured to output electrical signals to control valves 13 and 14. Next, the operation of the driving force distribution control device configured as described above will be explained with reference to FIGS. 3(2) to 3(C). First, during normal driving, the valve opening degrees of the hydraulic control valves 13 and 14 are set to be equal based on the output signal of the processing circuit 21 of the control unit 18, so that the clutch hydraulic pressure of the front and rear wheel clutches 4.7 is also equal, and The driving force distribution of .9 is 1
:1. In this state, there is a puddle 8 while the vehicle C is turning on the turning path A shown in FIG.
When the value becomes smaller than the value of the ideal yaw angular velocity φS depending on the steering angle and vehicle speed, and there is a tendency for understeer, the processing circuit 21
The valve opening degrees of the hydraulic control valves 13 and 14 change according to the output signal. Then, the clutch oil pressure of the front wheel clutch 4 is lowered to reduce the driving force of the front wheels 6, and the clutch oil pressure of the rear wheel clutch 7 is increased to increase the driving force of the rear wheels 9, as shown in (C). [Correct the deviation in yaw angular velocity using R-like drive distribution. On the other hand, if the value of the actual yaw angular velocity φ recovers as shown in Φ) due to the above-mentioned FR driving and conversely becomes larger than the value of the ideal yaw angular velocity φS, resulting in a tendency towards over-busteer, as shown in (C), the above-mentioned situation will occur. This results in a reverse FE-like driving force distribution. By controlling the distribution of driving force between the front and rear wheels 6.9 in response to the disturbance caused by the puddle shade, the vehicle yaws in accordance with the ideal yaw angular velocity desired by the driver. The case where control is performed in relation to the yaw angular velocity during turning has been described above, but it is also possible to smooth the turning movement itself in relation to the steering angle. That is, as shown in FIG. 1, the output signal of the processing circuit 21 is controlled by the signal from the steering angle sensor 16. As shown in Figure 4 (2) to C), in the case of a swinging bamboo pole, the turning performance is improved by distributing the driving force in an R-like manner, and in the latter half, it is stabilized by distributing the driving force in an R-like manner. This makes it possible to obtain ideal steering performance.For this reason, if control is based on the steering angle based on the steering angle described above, and yaw angular velocity 1iIII control is added to this control, turning It becomes possible to further improve the characteristics. [Effects of the Invention] As described above, according to the present invention, when turning
Since the drive force distribution between the front and rear wheels is controlled so that the vehicle travels along the ideal yaw angular speed based on first gear and the steering angle, it is possible to yawner according to the driver's intention in response to disturbances, driving errors, etc. Improves driving performance and safety. Rudder angle, I! Since the driving force distribution is controlled by input signals such as speed, it is easy to enrich and expand the content of control.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram showing an embodiment of the driving force distribution control device of the present invention, Fig. 2 is a diagram used for calculating yaw angular velocity, and Fig. 3 (2) to C) shows yaw angular velocity control. Figures 4(2) to 4(C) are diagrams showing control during turning. 4... Front wheel clutch 7... Rear wheel clutch 13, 14... Hydraulic pressure control valve 15... Vehicle speed sensor 1G... Rudder angle sensor 17... Yaw angle sensor 18... Control unit

Claims (1)

[Claims] A four-wheel vehicle that calculates an ideal yaw angular velocity based on vehicle speed and steering angle sensor signals, and controls driving force distribution between the front and rear wheels so that the actual yaw angular velocity measured by the yaw angle sensor matches the ideal yaw angular velocity. Drive force distribution control device for drive vehicles.