Vehicle speed control system

Abstract

A vehicle speed sensor is connected to a fluid pressure source such as the engine intake manifold and produces a pressure output corresponding to vehicle speed. An actuator in the form of a diaphragm assembly positions the engine fuel control member in accordance with the pressure output of the speed sensor so as to decrease the amount of fuel for combustion as the vehicle speed increases and vice-versa so that the vehicle speed is maintained at a predetermined value regardless of vehicle load. A normally open exhaust brake valve is provided in the engine exhaust system and is automatically closed to block the exhaust system and thereby brake the engine when the speed control system is energized and the fuel control member is moved by the actuator to a minimum fuel demand position. This condition occurs when the vehicle is rolling downhill or the like and the vehicle speed cannot be limited to the predetermined value by fuel control alone. Various switches are provided to automatically de-energize the speed control system when the operator depresses a brake pedal, a clutch pedal, a manual exhaust brake switch and when the vehicle speed exceeds the predetermined value by a predetermined amount.

Dependencies are inferred from the claim text.