Carburetor throttle valve positioner

Claim 1

A carburetor throttle valve positioner comprising, in combination, an engine carburetor having an induction passage open to atmospheric pressure at one end and adapted to be connected to an engine intake manifold at the opposite end so as to be subject to engine vacuum varying in level from ambient atmospheric pressure at engine shutdown to a maximum subatmospheric pressure level during engine deceleration operating conditions, a throttle valve rotatably mounted across said passage and movable from a closed position to an engine idle speed position and beyond to a wide open throttle position, and return, for controlling flow through said passage, an idle fuel/air mixture passage connected to said induction passage around said throttle valve and having a discharge end connected to said induction passage at a location above the closed throttle valve position but adapted to be traversed by the throttle valve as it moves towards an open position so that the idle passage is subjected to manifold vacuum when the throttle valve is positioned beyond the closed position to provide normal idle and beyond normal idle speed mixture flow and subjected to ambient pressure level during closed throttle valve position to terminate idle mixture flow, and control means to move said throttle valve to and between said positions, said control means including first means operatively acting on and biasing said throttle valve to an open beyond normal engine idle throttle position, second engine manifold vacuum responsive means operatively acting on said first means permitting return movement at times of said throttle valve to a normal engine idle speed position during operation of said engine, third movable stop means to prevent return movement of said throttle valve to a position less open than said normal idle position during operation of said engine, and means to withdraw said stop means upon engine shut down to permit movement of said throttle valve to a closed anti-dieseling position.