Patent ID: 8230681
Filing Date: 2012-07-31
Classification: F02M,F28F

Abstract:
1. An exhaust gas switching valve comprising: (a) a housing having four exhaust gas ports which respectively communicate with an exhaust passage of an internal combustion engine, an intake passage of an internal combustion engine, an inlet of an exhaust gas cooler and an outlet of the exhaust gas cooler, and (b) a valve rotatably accommodated in the housing to switch a communicating condition between four exhaust gas ports, wherein according to a rotational angle position of the valve in the housing, the exhaust gas switching valve switches between a cooler mode in which an exhaust gas is introduced into the exhaust gas cooler to be cooled and a bypass mode in which the exhaust gas bypasses the exhaust gas cooler, said four exhaust gas ports correspond to a gas inlet port communicating with the exhaust passage of the internal combustion engine, a gas outlet port communicating with the intake passage of the internal combustion engine, a cooler inlet port communicating with an inlet of the exhaust gas cooler, and a cooler outlet port communicating with an outlet of the exhaust gas cooler, the valve is a butterfly valve including a shaft supported by the housing, a first valve plate and a second valve plate which are respectively connected to both side surfaces of the shaft, the housing includes a first gas passage connecting the gas inlet port to the cooler inlet port, a second gas passage connecting the cooler outlet port to the gas outlet port, a connecting portion connected to the exhaust gas cooler and a partition wall partitioning the cooler inlet port and the cooler outlet port, the partition wall extends from the connecting portion to a vicinity of the shaft, the valve has a center portion supported by the shaft, the first valve plate and the second valve plate are arranged opposite sides relative to the center portion, the first valve plate has an overlap portion which is brought into a contact with the partition wall in the second gas passage at the cooler mode and which overlaps the partition wall in the second gas passage at the cooler mode, the housing has an opening closed by at least the second valve plate at the cooler mode, a contacting position between the first valve plate and the partition wall is arranged at a vicinity of the shaft, the partition wall is arranged upstream of the first valve plate in a flow direction of the exhaust gas introduced from the gas inlet port, and the partition wall and the overlap portion configure a double wall structure with a gap clearance space therebetween at the cooler mode in such a manner that the exhaust gas introduced from the gas inlet port flows toward the cooler inlet port along a surface of the partition wall without contacting with the overlap portion of the first valve plate.