Internal combustion engine air intake control systems

Claim 1

A sensor unit for use in an internal combustion engine having an induction passage for air flow to the engine, a throttle disposed in said induction passage for controlling flow therethrough, said induction passage having a first inlet for receiving ambient temperature air and a second inlet for receiving air warmed to temperatures above ambient temperature, valve means for controlling air flow through said inlets to regulate the temperature of the air flow to said engine, a spring biasing said valve means to permit increased ambient air flow through said first inlet and to decrease warmed air flow through said second inlet, a vacuum motor, and means linking said vacuum motor to said valve means to position said valve meaNs in accordance with variations in pressure sensed by said vacuum motor, said vacuum motor moving said valve means against the bias of said spring to permit increased warmed air flow through said second inlet and to decrease ambient air flow through said first inlet upon a decrease in pressure sensed by said vacuum motor, said sensor unit comprising a body, a closure plate secured to said body to define a chamber therewithin, said body having a first fitting adapted for sensing the pressure in said induction passage downstream of said throttle and a second fitting adapted for connection to said vacuum motor, said closure plate having an air bleed opening for admitting air to said chamber to increase the pressure therein, a bleed valve disposed in and controlling flow through said air bleed opening, means adapted for response to the temperature of induction air flow in said induction passage downstream of said inlets for positioning said bleed valve to permit increased air flow through said air bleed opening upon an increase in said induction air flow temperature and for positioning said bleed valve to decrease air flow through said air bleed opening upon a decrease in said induction air flow temperature, said second fitting having a valve seat formed therein, a pressure responsive non-return valve engageable with said valve seat when the pressure in said first fitting exceeds the pressure in said second fitting to prevent flow from said first fitting through said chamber to said second fitting and disengaged from said valve seat when the pressure in said second fitting exceeds the pressure in said first fitting to permit flow from said second fitting through said chamber to said first fitting, and a temperature responsive member disposed in said chamber and engageable with said non-return valve at temperatures above a selected level to disengage said non-return valve from said valve seat to permit flow through said chamber both from said first fitting to said second fitting and from said second fitting to said first fitting, said temperature responsive member being disengaged from said non-return valve at temperatures below said selected level to permit said non-return valve to engage said valve seat, said second fitting being adjustable relative to said temperature responsive member for varying the selected temperature level above which said temperature responsive member disengages said non-return valve from said valve seat, whereby when the temperature in said chamber is below said selected level said non-return valve permits flow from said vacuum motor to said induction passage and prevents flow from said induction passage and said air bleed opening to said vacuum motor and said vacuum motor positions said valve means to maximize warmed air flow through said second inlet and minimize ambient air flow through said first inlet, and whereby when the temperature in said chamber is above said selected level said temperature responsive member disengages said non-return valve from said valve seat and said vacuum motor senses the pressure created in said chamber by the induction passage pressure sensed through said first fitting and the air flow admitted through said air bleed opening and positions said valve means accordingly.