Arrangement for deriving intake negative pressure from an

Abstract

An arrangement for deriving intake negative pressure from an internal-combustion engine, comprising a carburetor in the latter, with an intake for an air -- fuel mixture, a throttle valve therein for regulating the mixture, and at least one longitudinal passage therein for guiding the mixture toward the engine; an intake passage leading from the carburetor to the engine; which latter also has an exhaust passage leading therefrom; wherein the throttle valve has a shaft substantially transversally disposed in one of the passages of the carburetor, the latter being fitted with a discharge opening in a side wall of the intake passage to derive negative passage from the carburetor for regulating and controlling the engine operation; the discharge opening being provided in the flow of the mixture, in an area that is directed downstream from the throttle-valve shaft; whereby to avoid accumulation and discharge of condensed fuel from the carburetor to the discharge opening. The arrangement can be associated with a control circuit for the engine, including pressure-responsive elements, as well as an air pump for delivering secondary air to the exhaust passage of the engine. According to an important feature of the invention, an insert member is interposed between the body of the carburetor and the intake passage, with a connecting tube being integrally formed in the insert member but projecting therefrom, which tube is in communication with the discharge opening.