Stop-start device for a motor vehicle engine

Claim 1

A stop-start device for a motor vehicle engine comprising a starting circuit for starting the engine, which comprises at least one start button bridging a starter switch, and comprising a switching member whose switching condition for switching off the engine is variable through a stop button and/or through a road-speed-dependent switch, characterized in that with the change of the switching condition of the switching member particular consumers in the motor vehicle are changed over to a mode of operation with a lower current consumption; wherein the revolutional speed of the electric motor for a power-assisted braking system or steering system is reduced; wherein upon switching on the engine again the mode of operation adjusted through the operating switch (34) of the consuming device (35) before switching off is again turned on; wherein the switching condition of the switch member (21) may be affected by further switching elements (41, 43, 44) which are controlled in dependence on particular operating conditions on the motor vehicle and, when these particular operating conditions exist, prevent a change in the switching condition of the switching member (21) irrespective of the stop button and/or the road-dependent switch (23) being actuated; wherein further switching elements are dependent on the operating conditions of the engine and especially in the case of a too high oil temperature and/or a too high cooling water temperature a switching-off of the engine is prevented; and, in which the switching member is controlled via a delay circuit in dependence on a road-speed dependent switch, and wherein the delay time of the delay circuit (22) may be affected in dependence on the switching position of particular switch elements (48).