Patent ID: 8041486
Filing Date: 2011-10-18
Classification: B60W,F16H

Abstract:
1. A method of gear shifting in a servo-controlled gearbox for shifting from a first current gear to a second next gear, the gearbox including at least one primary shaft connected to a crankshaft of an engine by a clutch and a secondary shaft connected to drive wheels, the method comprising: generating an oscillation on angular velocities of the primary and secondary shafts before disengaging the first current gear; separating the primary shaft from the secondary shaft thus disengaging the first current gear when the oscillation of the angular velocity of the primary shaft has taken the angular velocity of the primary shaft close to the angular velocity that the primary shaft must assume to engage the second next gear; connecting the primary shaft to the secondary shaft thus engaging the second next gear; connecting the primary shaft to the secondary shaft thus engaging the second next gear when the oscillation of the angular velocity of the secondary shaft has led the angular velocity of the secondary shaft to equalize the current angular velocity of the primary shaft multiplied by the transmission ratio of the second next gear; calculating for each operation an estimated delay time corresponding to the time interval elapsing from the instant in which the actuation of the operation is commanded and the instant in which the operation itself is actually completed; commanding the actuation of a first operation at a first instant of time; calculating a second instant of time in which the first operation will be actually completed, adding the delay time estimated for the first operation itself to the first instant of time in which actuation of the first operation was commanded; determining a third instant of time in which to command the actuation of the second next operation subtracting the delay time estimated for the second operation decreased by a safety constant, whose function is to avoid overlapping between the completion of the first operation and the completion of the second next operation, from the second instant of time; and commanding the actuation of the second next operation when the third instant of time is reached.