Abstract: In an inner fin, a plate is made up of a top part, a bottom part, and a wall plate part, and a channel having a concave-shaped cross section and a channel having an inverted concave-shaped cross section are alternately repeated as channels of the gas by a pair of the wall plate parts facing each other. The wall plate part for each of the channels has a shape in which the wall plate part is bent left and right in a serpentine shape and projected and recessed parts thereof are alternately repeated and formed, and the recessed part of the wall plate part is formed with a chevron-shaped part made up of an upward slope part that ranges from a base part to the top part and a downward slope part that passes downward from the top part to a neighboring base part.

Abstract: In an inner fin, a plate is made up of a top part, a bottom part, and a wall plate part, and a channel having a concave-shaped cross section and a channel having an inverted concave-shaped cross section are alternately repeated as channels of the gas by a pair of the wall plate parts facing each other. The wall plate part for each of the channels has a shape in which the wall plate part is bent left and right in a serpentine shape and projected and recessed parts thereof are alternately repeated and formed, and the recessed part of the wall plate part is formed with a chevron-shaped part made up of an upward slope part that ranges from a base part to the top part and a downward slope part that passes downward from the top part to a neighboring base part.

Abstract: There is provided an EGR cooler having a core portion in which a large number of flat tubes through which exhaust gases pass are stacked one on another in an interior of a hollow cylindrical shell to be joined to the shell for heat exchange between the exhaust gases and a cooling fluid which flows around the tubes, a cylindrical inlet header which is joined to an upstream side of the shell in relation to a gas flow at one end thereof, and a cylindrical outlet header which is joined to a downstream side of the core portion in relation to the gas flow at one end thereof, characterized in that the inlet header and the outlet header are joined to an outer surface of the shell, and the tubes are joined to an inner surface of the shell at those joint portions.

Abstract: There is provided an inner fin wherein: a sheet material is formed into an offset configuration in which grooves and ridges are formed alternately in a widthwise direction, and the grooves and the ridges are offset laterally at right angles to a gas flowing direction at predetermined length intervals in an alternate fashion; and a first projection and a second projection are formed for each segment surrounded by a pair of left and right side walls, by cutting either an upper surface portion or a lower surface portion and causing the cut surface portion to stand, the first projection being inclined towards an upstream side of the gas flowing direction, the second projection being disposed downstream of the first projection and being inclined towards a downstream side of the gas flowing direction at an angle equal to an angle at which the first projection is inclined.

Abstract: There is provided an EGR cooler having a core portion in which a large number of flat tubes through which exhaust gases pass are stacked one on another in an interior of a hollow cylindrical shell to be joined to the shell for heat exchange between the exhaust gases and a cooling fluid which flows around the tubes, a cylindrical inlet header which is joined to an upstream side of the shell in relation to a gas flow at one end thereof, and a cylindrical outlet header which is joined to a downstream side of the core portion in relation to the gas flow at one end thereof, characterized in that the inlet header and the outlet header are joined to an outer surface of the shell, and the tubes are joined to an inner surface of the shell at those joint portions.