| 主权项 |
1. A supercharged internal combustion engine, comprising:
a compressor that supercharges intake air; an EGR passage that connects an intake passage at an upstream side of the compressor and an exhaust passage; an EGR valve that is provided in the EGR passage, and regulates a flow rate of EGR gas that flows through the EGR passage by opening and closing the EGR passage; a seal portion that seals a space between the EGR valve and a wall surface of the EGR passage; and a heat insulator that is provided on a surface of the EGR valve that is exposed to the EGR passage which is located at an upstream side in an EGR gas flow with respect to the seal portion when the EGR valve is in a fully closed position, wherein the heat insulator is not provided on a surface of the EGR valve that corresponds to the seal portion, wherein the EGR valve is a poppet type EGR valve having a valve body that is umbrella-shaped and opens and closes the EGR passage, and a valve shaft one end of which is fixed to the valve body, wherein the valve body includes a seal surface that is in contact with a valve seat which is provided on the wall surface of the EGR passage when the valve body is seated on the valve seat, wherein the heat insulator is provided on the surface of the valve body that is exposed to the EGR passage which is located at the upstream side in the EGR gas flow with respect to the seal surface, wherein the valve body includes an umbrella surface that is a surface of the valve body at a side opposite from a site to which the valve shaft is fixed, and a side circumferential surface that is a surface of a site that is located between the umbrella surface and the seal surface, wherein the heat insulator is formed so as to cover the umbrella surface, and so as to be in contact with a wall surface of the EGR passage which is located at an upstream side of the valve seat in an EGR gas flow direction, throughout an entire circumference of the wall surface, when the valve body is in a fully closed position, and wherein a gap that is present between the side circumferential surface and the wall surface of the EGR passage facing the side circumferential surface when the valve body is in the fully closed position is separated, by the heat insulator, from an internal space of the EGR passage that is located at an upstream side of the gap in the EGR gas flow direction. |
