Fluid-pressure and analogous brake systems – Speed-controlled – With yaw control
Patent
1997-02-07
1998-12-01
Graham, Matthew C.
Fluid-pressure and analogous brake systems
Speed-controlled
With yaw control
3031135, B60T 824, B60T 858
Patent
active
058427546
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a turn control apparatus for a vehicle, and more specifically, to an apparatus for controlling yawing of a vehicle.
BACKGROUND ART
Yaw rate sensors for detecting yaw rates that indicate the degree of yawing of objects go into actual use and are used in operation control for vehicles. For example, in the brake force control apparatus disclosed in Jpn. Pat. Appln. KOKAI Publication No. 5-105048, when a vehicle is judged to be in the oversteer mode in accordance with an actual yaw rate detected by a yaw rate sensor and a target yaw rate computed based on a steering angle and vehicle speed, the braking forces for the right and left front wheels are controlled to produce a restoration moment on the vehicle, and when judged to be in the understeer mode, the braking forces for the right and left rear wheels are controlled to produce a turning moment, whereby the vehicle turn is controlled.
For the vehicle turn control apparatus of this type, generally, whichever the vehicle is in the oversteer mode or the understeer mode, the turn control is started after a given time has elapsed from the point of time when yawing begins to be detected by a yaw rate sensor.
However, in the case where the turn control is started at a given timing regardless of whether the vehicle is in the oversteer mode or the understeer mode, when the degree of oversteer is great, there is a possibility of the occurrence of spinning of the vehicle before a required restoration moment is produced on the vehicle by the execution of turn control. In this case, it is difficult to recover the vehicle posture by the execution of turn control.
In the apparatus disclosed in Jpn. Pat. Appln. KOKAI Publication No. 5-105048, the turn control is started as soon as a deviation between the actual yaw rate and the target yaw rate occurs. In this case, the yaw control sometimes cannot be carried out smoothly.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a turn control apparatus for a vehicle, which can quickly prevent spinning of a vehicle in the oversteer mode and achieve smooth yaw control.
To achieve the above object, according to the present invention, there is provided a turn control apparatus for a vehicle, which includes a control unit for selectively carrying out yaw acceleration control where a braking force difference to generate a turning moment on the vehicle is produced between target wheels to be controlled and yaw inhibition control where a braking force difference to generate a restoration moment on the vehicle is produced between the target wheels to be controlled, in accordance with a state variable representing at least one of the vehicle operating state and the vehicle behavior. This apparatus comprises timing means for setting the start timing of the yaw inhibition control and the start timing of the yaw acceleration control. The start timing of the yaw inhibition control is set so as to be earlier than the start timing of the yaw acceleration control.
The advantage of the present invention is that when a brake force difference for accelerating or inhibiting yawing of the vehicle is produced between the wheels, the yaw inhibition control can be started at earlier timing than the yaw acceleration control. When the vehicle is oversteer-prone, therefore, the required restoration moment can quickly be produced on the vehicle, thereby preventing spinning of the vehicle. Also, since the yaw control is started at the required timing, the yaw control is not started suddenly, so that smooth yaw control can be achieved.
In the present invention, preferably, the control unit includes required control value calculating means for deriving a required control value associated with the yaw inhibition control and the yaw acceleration control in accordance with the state variable. The timing means sets a discrimination value associated with the start timing of the yaw inhibition control at a first predetermined value, and sets a discrimination value associated with the st
REFERENCES:
patent: 4998593 (1991-03-01), Karnopp
patent: 5302010 (1994-04-01), Ehmer et al.
patent: 5303989 (1994-04-01), Yasuno et al.
patent: 5455770 (1995-10-01), Hadeler et al.
Graham Matthew C.
Mitsubishi Jidosha Kogyo Kabushiki Kaisha
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