Exhaust gas recirculation control system
AssigneeNissan Motor Co., Ltd.
InventorSyunichi Aoyama
Life of this patent
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Abstract
A multiple spark plug ignition internal combustion engine is equipped with an EGR control system which consists of an EGR control valve disposed in an EGR passageway connecting an exhaust gas passageway and an intake passageway. The EGR control system is arranged to control EGR rate in accordance with venturi vacuum and in accordance with the exhaust gas pressure in the EGR passageway upstream of the EGR control valve. The EGR control system comprises a device for decreasing the EGR rate under a suburban area cruising condition of a motor vehicle on which the engine is mounted.
Claims17
An exhaust gas recirculation (EGR) control system in combination with an internal combustion engine of a motor-vehicle including a combustion chamber, an intake passageway providing communication between the atmosphere and the combustion chamber, a venturi formed in the intake passageway, a throttle valve rotatably disposed in the intake passageway downstream of the venturi, and an exhaust gas passageway providing communication between the combustion chamber and the atmosphere, said EGR control system comprising:
- Egr passageway means providing communication between the exhaust gas passageway and the intake passageway for recirculating exhaust gas back to the combustion chamber;
- a diaphragm actuated EGR control valve operatively disposed in said EGR passageway means to divide said EGR passageway means into an upstream portion connecting to the exhaust gas passageway and a downstream portion connecting to the intake passageway, said EGR control valve being operative in opposite directions to increase and decrease the pressure of the exhaust gas in the upstream portion of said EGR passageway means to control the flow of the recirculated exhaust gas, the diaphragm of said EGR control valve defining a first chamber which communicates through first passage means with the intake passageway to provide the first chamber with an intake vacuum in the intake passageway;
- control means for controlling the intake vacuum provided to the first chamber of said EGR control valve to increase and decrease the exhaust gas pressure in the upstream portion of said EGR passageway means in accordance with a decrease and an increase in the exhaust gas pressure in the upstream portion, respectively, and in accordance with a decrease and an increase in a vacuum in said venturi, respectively;
- and
- means for decreasing the degree of the intake vacuum provided to the first chamber of said EGR control valve under a suburban area cruising condition of the vehicle.
Dependencies are inferred from the claim text.