Device for selectively cooling a motor vehicle engine exhaust gases

Device for cooling exhaust gases of the engine of a motor vehicle, fitted into the path of the exhaust gases in an exhaust line of the vehicle, comprising a first gas flow path in at least one first pipe that is in contact by way of its outer wall with cooling air, and a second gas flow path, having a length greater than the length of the first flow path, constituted by at least one second pipe having an outer wall in contact with cooling air, and means for directing the exhaust gases totally towards the first or at least principally towards the second flow path, which means are controlled as a function of a thermal operating parameter of the exhaust line of the engine, wherein the device includes, in an outer casing that is substantially cylindrical in shape and through the lateral wall of which there pass openings in which casing there are arranged the first path constituted by a tube extending in an axial direction of the cylindrical casing, and the second flow path constituted by a plurality of tubes fixed by holding means in substantially parallel arrangements, in an axial direction of the cylindrical casing, a pipe for the admission of exhaust gases into the cylindrical casing, which pipe is connected to an upstream part of the exhaust line, an exhaust gas evacuation pipe connected to a downstream part of the exhaust line, and exhaust gas distribution pipe means arranged inside the cylindrical casing and connecting the admission pipe with end intake parts of the first and second paths, connecting end outlet parts of the first and second paths with the evacuation pipe, and connecting together intermediate parts of the second path constituted by tubes of the plurality of tubes, the directing means being constituted by at least one valve operated to open and close an end intake part of at least one of the flow paths.