Cruise control system for a vehicle

摘要

A cruise control system for a vehicle having an internal combustion engine is provided with a throttle valve operated by a diaphragm actuator irrespective of a depression of an accelerator pedal by an operator of the vehicle. The system is provided with a control circuit for controlling an electric signal applied to the actuator. A fixed level signal is first applied to the actuator for a short period after a cruise mode operation has commenced, so that the diaphragm is quickly moved to prevent a temporary decrease in the vehicle speed. After the elapse of the predetermined time, the level of the electric signal is controlled by feedback so that the vehicle speed is controlled to a target speed. A feedback gain initially has a first value for a period after the feedback control is commenced and then has a second value which is smaller than the first value. Furthermore, the feedback gain may have a third value at a transient state from a condition where the feedback gain has the first value and a condition where the feedback gain has the second value.