Motor vehicle exhaust gas heat exchanger for heating engine coolant and lubricating oil

In a combination of an internal combustion engine comprising a cooling circuit containing a cooling liquid and a lubricating circuit containing a lubricating liquid, and a heat exchanger comprising a bundle of tubes, a perforated plate in which the ends of said tubes are sealingly mounted, a fluid box fixed to said perforated plate opposite to said tubes with the ends of said tubes opening into said fluid box, means to introduce exhaust gas from said engine into said bundle of tubes at one end and to withdraw the gas from said bundle of tubes at the opposite end, the improvement comprising:

• an envelope surrounding said bundle of tubes having an inlet means and an outlet means connected in said cooling circuit, said envelope being formed of a material adapted to withstand at least approximately the highest expected temperature of the cooling liquid, but less than the highest expected temperature of the exhaust gas, a tubular element surrounding said bundle of tubes and interposed between said perforated plate and said envelope, said tubular element, said fluid box and said perforated plate being formed of a material adapted to withstand the highest expected temperature of the exhaust gas, and at least one duct within said envelope in heat exchange relationship with the cooling liquid having inlet and outlet means passing through said envelope and being connected in said lubricating circuit.