| 摘要 |
PURPOSE:To prevent a vehicle from running away even if a brake switch fails, by providing such an arrangement that when the lowering rate of rotational speed of an engine exceeds a predetermined value, the control of constant speed travel is released. CONSTITUTION:A constant speed travel detecting device 1 is constituted such that a controller compares an actual vehicle speed detected by a vehicle speed sensor 9 with a set vehicle speed, and therefore, controls the opening degree of a throttle valve to make both speeds coincide with each other. Accordingly, controls receives the rotational speed of an engine detected by an engine rotational speed sensor 30 so that the lowering rate dN/dt of the engine rotational speed is calculated. If it is determined that the lowering rate exceeds a predetermined value, the controller 5 deenergizes all solenoids 11a, 12a, 13a to release the control of the constant speed and therefore, the throttle valve is actuated by manipulating an accelerator pedal. Thus it is possible to release the control of constant speed travel by brake operation when the engine rotational speed lowers even if a brake switch fails. |
