Exhaust gas recirculation valve

Claim 1

An exhaust gas recirculation control valve assembly for use on an internal combustion engine having an induction passage for air flow to the engine, a throttle disposed in said induction passage and rotatable between closed and open positions for controlling air flow therethrough, an exhaust passage for exhaust gas flow from the engine, a recirculation passage having a first portion extending from said exhaust passage and a second portion extending to said induction passage downstream of said throttle, said valve assembly comprising a base member having upper, peripheral, and lower walls defining a chamber, said lower wall further defining an inlet for receiving exhaust gases from said first recirculation passage portion and an outlet for discharging exhaust gas to said second recirculation passage portion, a valve seat formed in said inlet, a valve pintle associated with said valve seat for controlling exhaust gas flow therethrough, a valve stem secured to said valve pintle and extending through said chamber and said upper wall, a first diaphragm secured to said valve stem outside said chamber, the lower side of said diaphragm being exposed to atmospheric pressure, a second diaphragm secured to said valve stem above said first diaphragm and defining a second chamber between said diaphragms, means subjecting said second chamber to the pressure in said induction passage downstream of said throttle, said second diaphragm having an effective area greater than the effective area of said first diaphragm whereby the pressure in said second chamber creates a greater force on the lower side of said second diaphragm than on the upper side of said first diaphragm, means defining a third chamber on the upper side of said second diaphragm, and means subjecting said third chamber to the pressure signal created at a port in said induction passage disposed adjacent and traversed by the edge of said throttle.