Solenoid valve control for exhaust gas recirculation

Claim 2

In an internal combustion engine, an intake passage for air flow to the engine, a throttle in said intake passage for controlling air flow therethrough, an exhaust for the flow of exhaust gases from the engine, an exhaust gas recirculation passage fluidly connecting said exhaust passage with said intake passage downstream of said throttle, a valve in said exhaust gas recirculation passage for controlling flow of the exhaust gaSes, said valve being movable between an open position and a closed position, a solenoid operatively connected to said valve for moving said valve to said open position when energized and to said closed position when deenergized; circuit means including amplifier means for energizing and deenergizing said solenoid during each engine cycle, a pressure transducer operatively positioned at said intake passage downstream of said throttle, said transducer being responsive to absolute pressure at said intake passage which pressure varies in accordance with throttle position and engine load, said circuit means including means responsive to said transducer and operative to control energization of said amplifier means to energize said solenoid for a variable period within each engine cycle in accordance with changes in intake passage pressure produced by changes in engine load and throttle setting to thereby provide a recirculation rate proportional to engine air flow.

Claim 3

In an internal combustion engine, an intake passage for air flow to the engine, a throttle in said intake passage for controlling air flow therethrough, an exhaust for the flow of exhaust gases from the engine, an exhaust gas recirculation passage fluidly connecting said exhaust passage with said intake passage downstream of said throttle, a valve in said exhaust gas recirculation passage for controlling flow of the exhaust gases, said valve being movable between an open position and a closed position, a solenoid operatively connected to said valve for moving said valve to said open position when energized and to said closed position when deenergized; circuit means including amplifier means for controlling energization of said solenoid, said circuit means including a signal generator producing a signal on each engine cycle and means to condition said amplifier means to energize and deenergize said coil on each engine cycle in response to said signal, a pressure transducer operatively positioned at said intake passage downstream of said throttle, said transducer being responsive to absolute pressure at said intake passage which pressure varies in accordance with throttle position and engine load, and means responsive to said pressure transducer to condition said circuit means to maintain said amplifier means conditioned to energize said coil for a variable period during each engine cycle established in accordance with changes in intake passage pressure produced by changes in engine load and throttle setting to thereby produce a recirculation rate proportional to engine air flow.

Claim 4

In an internal combustion engine, an intake passage for air flow to the engine, a throttle in said intake passage for controlling air flow therethrough, an exhaust for the flow of exhaust gases from the engine, an exhaust gas recirculation passage fluidly connecting said exhaust passage with said intake passage downstream of said throttle, a valve in said exhaust gas recirculation passage for controlling flow of the exhaust gases, said valve being movable between an open position and a closed position, a solenoid operatively connected to said valve for moving said valve to said open position when energized and to said closed position when deenergized; circuit means including amplifier means for controlling energization of said solenoid, said circuit means including a signal generator producing a signal on each engine cycle and means to condition said amplifier means to energize and deenergize said coil on each engine cycle in response to said signal, a pressure transducer operatively positioned at said intake passage downstream of said throttle, said transducer being responsive to absolute pressure at said intake passage which pressure varies in accordance with throttle position and engine load, and means responsive to said pressure transducer to condition said circuit means to maintain said amplifier means conditioned to energize said coil for a variable period during each engine cycle established in accordance with changes in intake passage pressure produced by changes in engine load and throttle setting to thereby produce a recirculation rate proportional to engine air flow.