This paper deals with the study of the dynamic behavior of a F1 car gear selection hydraulic circuit, when involved in different shift transients.
In the first part of the paper the actual circuit is described, and the main hypotheses adopted for the numerical modeling of the hydraulic power unit, of the control valves, of hydraulic pipes and of the actuators involved in the gear shift cycles are introduced. Particular attention is devoted to the actuators actual sequences, as applied by the Electronic Control Unit (ECU) to the servo-valves deputed to actuators control. The strategy to define each gear shift cycle in terms of actuators working position in time domain is chosen, using the frequency map of each servo-valve.
A numerical vs. experimental comparison of the behavior of the actuators involved in the gear selection (during about 50 ms for an up shifting and 100 ms for a down shifting) is performed, with the target to define the validity limits of the numerical model results.
Finally, the paper reports the analysis of those hydraulic variables not controlled by the on board diagnostic, with the aim to analyze the behavior of the power unit and of the pipes when submitted to the sudden hydraulic power request correspondent to a gear shift.