Exhaust gas recirculation system for an automobile engine, including a high altitude compensator

Abstract

Disclosed is an exhaust gas recirculation system for an automobile engine, provided with a high altitude compensator. The high altitude compensator has an atmospheric chamber in which a first valve is adapted to open when the automobile reaches a predetermined altitude. The opening of this valve is enlarged in proportion to an increase in the altitude. The system also includes a second valve for exhaust gas recirculation control having a negative pressure chamber communicated with a first pressure sensing port opening to the carburetor. This valve controls the amount of the exhaust gas recycled into the intake side of the engine according to variation in the pressure of the negative pressure chamber. The system further includes a third or air flow switching valve having a negative pressure chamber communicated with a second pressure sensing port opening to the carburetor. This valve controls the amount of the air supplied into the exhaust side of the engine according to variation in the pressure of the negative pressure chamber. The atmospheric pressure chamber of the high altitude compensator is connected with both the negative pressure chambers of the second and third valves. The present system prevents a large decline in the engine power output, an unduly heavy generation of NO.sub.x and uncombusted HC and CO and thermal damage to the exhaust circuit of the engine during engine operation at a high altitude.

Dependencies are inferred from the claim text.