초록 ▼

This invention relates to a speed control system which is operable to maintain a vehicle at a selected speed, or to prevent the vehicle speed dropping below the selected speed. The system includes an electrically-operable pressure control valve which is arranged to be fed with fluid from a source of

This invention relates to a speed control system which is operable to maintain a vehicle at a selected speed, or to prevent the vehicle speed dropping below the selected speed. The system includes an electrically-operable pressure control valve which is arranged to be fed with fluid from a source of fluid pressure, for example from the transmission oil pump of an automatic transmission system, an electronic control circuit having a memory in which a selected vehicle speed can be set by the driver, and which supplies a control signal in the form of a variable mark/space ratio pulse train representative of the difference between the actual and selected speeds, to the electrically operable control valve. Fluid pressure from the pump is applied to the smaller working area side of a displaceable differential piston of a differential area piston arrangement, and the larger working area side of the differential piston is connected to the output side of the control valve. The control valve is modulated by the variable control signal to correspondingly vary the pressure applied to the larger area side of the differential piston, and correspondingly displace the piston. The piston is connected by a linkage arrangement to the vehicle engine to control the latter in order to maintain said selected vehicle speed. Means are provided, between the driver-operated accelerator pedal and the engine, to permit driver control of the engine to be overridden by the system.

대표청구항 ▼

A system for enabling a vehicle to maintain a selected vehicle speed, which system comprises; an electrically-operable pressure control valve arranged to be fed with fluid from a source of fluid pressure; an electronic control circuit having a memory in which a selected vehicle speed can be set and

A system for enabling a vehicle to maintain a selected vehicle speed, which system comprises; an electrically-operable pressure control valve arranged to be fed with fluid from a source of fluid pressure; an electronic control circuit having a memory in which a selected vehicle speed can be set and which is arranged to supply a signal, representative of the difference between the actual and selected speeds, to the electrically-operable control valve; a differential area piston arrangement, to the smaller working area side of the differential piston of which the fluid source pressure is fed, and to the greater working area side of the differential piston of which the output pressure of the control valve is supplied; and means coupled between the differential piston and the engine of the vehicle, the position of the piston being used to control the vehicle engine in order to maintain said selected vehicle speed.