Abstract: An integral device for controlling the rate of throttle closure and for preventing after run of an internal combustion engine is provided which utilizes a pair of diaphragm assemblies for accomplishing both functional operations. The device includes a dash pot stem having an axial opening through it. The opening is operatively connected to a source of engine vacuum. A diaphragm housing defining a chamber has a pair of diaphragm assemblies positioned in it. A first diaphragm assembly is mounted to the dash pot stem. The second diaphragm assembly is movably mounted on the dash pot stem and includes a shaft extending through the housing. The shaft is engagable with suitable linkage means operatively connected to a throttle valve of a carburetor for the engine. Upon engine start, the application of engine vacuum to a first side of the first diaphragm operates on the diaphragm and housing so that, in effect, the housing moves in a first direction, positioning the shaft at its curb idle position.

Abstract: A unitary device for controlling the rate of throttle closure and for preventing after run of an internal combustion engine is provided with simplified structure, the structure using a single shaft assembly for both functional operations. The shaft assembly is operatively connected to a diaphragm assembly which moves in response to forces acting to position the shaft assembly. The shaft assembly is an axially aligned and concentrically arranged combination, and includes a first shaft element which acts against the diaphragm assembly to bring a carburetor for an internal combustion engine slowly to its curb idle setting upon throttle release from some running condition. A second shaft element of the shaft assembly is controlled by a solenoid. The second shaft element acts against the diaphragm assembly upon ignition system de-energization, and permits the closure of the throttle below the curb idle setting of the carburetor.