Webasto Ag Fahrzeugtechnik

Wilfried Renovanz

Bernhard Umlauf

Dieter Raethel

Christof Schumacher

A heater, in particular a motor vehicle heater operated with liquid fuel in which the fuel to be fed to the burner of the heater is preheated using the thermal energy of the combustion gases in the discharge area of the heater to guarantee reliable operation of the heater even at low temperatures, and to prevent paraffin separations, especially with diesel fuel in advance of filter devices in the fuel supply of the burner. For this purpose, a fuel preheating pipe section is provided that can be made in the form of a spiral-shaped pipe loop and that is placed in the flow of combustion gases, which have passed through the heat exchanger of the heater. Since the fuel is warmed in the fuel flow pipe before passage through the filter device, clogging of the filter device is avoided. In accordance with various embodiments the fuel preheating pipe section can be placed in an exhaust gas collecting chamber of the heater or in an exhaust gas discharge connection. Another embodiment feature includes the provision of a second heat exchanger that warms the fuel to being fed to the internal combustion engine using the liquid coolant that was previously warmed in the motor vehicle heater and which also serves as the heat exchange medium for the heat exchanger of the heater.

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Groebenzell, Germany

Wilfried Renovanz