Automobile speed control method and system

An automatic speed control system for an automobile having a fuel injection engine and a throttle valve, and comprising:

• a speed signal generator circuit which generates a first electrical signal indicating actual automobile speed;
• desired automobile speed signal supply circuit means which supplies a second electric signal indicating desired automobile speed in response to a speed set operation of the automobile driver;
• an electronic fuel injection control device which produces a fuel injection control signal;
• a feedback signal generator circuit which generates a third electric signal indicating fuel injection rate in response to the fuel injection control signal from the electronic fuel injection control device;
• a comparator circuit combining said first, second and third signals to provide an engine throttle valve control signal;
• and
• servomotor means for driving the throttle valve in response to the throttle valve control signal.

An automatic speed control system for an automobile having a fuel injection engine and a throttle valve, and comprising

• a speed signal generator circuit which generates a first electrical signal indicating actual automobile speed;
• a memory circuit having a memory capacitor, an impedance converter means connected to the memory capacitor for supplying a second electric signal indicating desired automobile speed and a switching means connected to the memory capacitor for supplying it with the first electric signal;
• a switch circuit having a set switch which energizes the switching means in the memory circuit to turn ON;
• an electronic fuel injection control device which produces a pulsating fuel injection control signal;
• an integration circuit which receives the pulsating fuel injection control signal from the electronic fuel injection control device and generates a third electric signal indicating fuel injection duration;
• a comparator circuit combining said first, second and third signals to provide a throttle valve control signal;
• and
• servomotor means for positioning the throttle valve and comprising a solenoid valve which is energized by the throttle valve control signal through an amplifier, and a vacuum actuator which is driven by the vacuum pressure in the engine intake manifold through the solenoid valve.