Browse Publications Technical Papers 2018-01-1881

Improvement of the Methods of Evaluating the Dynamics of Brake Dynamics with Failure of ABS 2018-01-1881

Analysis of known methods for determining the rational choice of the distribution of braking forces between the axes made it possible to reveal a number of inaccuracies and contradictions, to which the following can be attributed: traditionally determine the distribution of limiting forces on the adhesion of wheels to the road in case of emergency braking of cars, and according to it - distribution of brake moments, which does not take into account the influence of inertial masses applied to the wheels; when determining the normal reactions on wheels and their redistribution between the axles, the change in the point of application of the braking force when locking the wheels is not taken into account (with the wheels unblocked, the braking force is applied to the wheel axle, and with the wheels locked, in the contact spot of the wheels with the road). The article provides analytical expressions that allow the rational choice of the distribution of the brake moments between the front and rear axle wheels, taking into account the inertial masses of the transmission. It is shown that the known law of the ideal distribution of tangential reactions between the axes corresponds to the braking of the car with all the blocked wheels. If it is necessary to simultaneously bring to the verge of blocking the front and rear wheels, one must be guided by another law of distribution of braking forces between the axles, at which the front brakes are weakened and the rear brakes are strengthened. Simultaneous bringing to the verge of blocking the front and rear wheels does not prevent ahead locking of the rear wheels. It is determined that the failure of the ABS on the rear wheels and the continued operation of the ABS on the front wheels, makes it possible to improve the stability of the car (compared to the failure of the ABS on all wheels) by increasing the normal load on the rear wheels. The received recommendations can be useful at development of brake systems of cars. They will allow increasing safety of braking of the car not only at refusal АВS, but also at service braking when АВS is not included in work.


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