Patent ID: 7527088

Claim:
An exhaust gas heat exchanger comprising: a plurality of exhaust gas tubes through which exhaust gas generated by combustion flows; a casing in which the plurality of exhaust gas tubes are arranged, defining a fluid passage therein through which fluid flows around the plurality of exhaust gas tubes to exchange heat with the exhaust gas; a fluid inlet disposed on the casing at an inlet side of the plurality of exhaust gas tubes through which the fluid flows into the casing along a direction substantially perpendicular to a longitudinal direction of the plurality of exhaust gas tubes; an outer space defined at a longitudinal position of the casing aligned with the fluid inlet between an inner wall of the casing and an outermost exhaust gas tube of the plurality of exhaust gas tubes, and extending longitudinally in a direction substantially parallel with an inflow direction of the fluid flowing into the casing through the fluid inlet; and a fluid flow regulating means provided in the fluid passage close to an upstream side of the plurality of exhaust gas tubes for regulating a stream of the fluid at a vicinity of the upstream side of the plurality of exhaust gas tubes so that the fluid after colliding with a side inner wall of the casing is led toward an upstream side of the plurality of exhaust gas tubes, the fluid flow regulating means extending in a direction crossing the longitudinal direction of the exhaust gas tubes; wherein a width of the outer space, in a direction substantially perpendicular to the inflow direction of the fluid and substantially perpendicular to the longitudinal direction of the plurality of exhaust gas tubes, is substantially equal to that of an inner space defined between adjacent exhaust gas tubes at the longitudinal position of the casing aligned with the fluid inlet; each of the plurality of exhaust gas tubes is a flat tube having a major dimension and a smaller minor dimension in a cross section; and the fluid flow regulating means extends longitudinally only in a direction of the major dimension in the cross-section of the flat tube.