Device for the automatic or manual selection of the ratio of a gearbox on a motor vehicle

Claim 1

A device for selecting the ratio of a gearbox of a vehicle, comprising, in combination: a motor vehicle having an engine, a mechanical clutch, and a direct drive gearbox; said gearbox having an input shaft; electronic means for placing the speed of said engine under the control of said input shaft of said gearbox, and for introducing a parameter which takes into account the intentions of the driver of said motor vehicle, said electronic means including memory means for memorizing said parameter imposed by said driver; a safety system operably and electronically connected to said electronic means for determining high and low speed limits of said vehicle for each said ratio and including indicator means and warning means which are actuated when one of said limits is overstepped upon a variation in the operating condition of said engine; said high and low speed limits for the ratio concerned correspond to the admissible maximum and minimum operating conditions, respectively, for said engine, while any overstepping of the range defined by said limits involves the change of the gearbox ratio systematically; and means for enabling the driver to select the smallest allowed ratio, including a transitory stop or kick-down device which is operated by a fleeting overstroke of the accelerator pedal in order to enable the driver to retrograde as much as possible; and the retrogradation control having been memorized by said memory means, while the passage to the smallest allowed ratio as imposed by said kick-down device is cancelled either when passing to a higher speed ratio, or when the device detects an acceleration beyond a certain limit which corresponds to the possibility of engaging the higher ratio when it is desirable to use the greatest ratio compatible with the safety system in order to limit the operating conditions of said engine.

Claim 2

A device for selecting the ratio of a gearbox of a vehicle, comprising, in combination: a motor vehicle having an engine, a mechanical clutch, and a direct drive gearbox; said gearbox having an input shaft; electronic means for placing the speed of said engine under the control of said input shaft of said gearbox, and for introducing a parameter which takes into account the intentions of the driver of said motor vehicle, said electronic means including memory means for memorizing said parameter imposed by said driver; a safety system operably and electronically connected to said electronic means for determining high and low speed limits of said vehicle for each said ratio and including indicator means and warning means which are actuated when one of said limits is overstepped upon a variation in the operating condition of said engine; said high and low speed limits for the ratio concerned correspond to the admissible maximum and minimum operating conditions, respectively, for said engine, while any overstepping of the range defined by said limits involves the change of the gearbox ratio systematically; and means for enabling the driver to select the smallest allowed ratio, including a transitory stop or kick-down device which is operated by a fleeting overstroke of the accelerator pedal in order to enable the driver to retrograde as much as possible; and the retrogradation control having been memorized by said memory means, while the passage to the smallest allowed ratio as imposed by said kick-down device is cancelled either when passing to a higher speed ratio, or when the device detects an acceleration beyond a certain limit which corresponds to the possibility of engaging the higher ratio when it is desirable to use the greatest ratio compatible with the safety system in order to limit the operating conditions of said engine.