Webasto Ag Fahrzeugtechnik

Webasto-werk W. Baier Gmbh & Co.

Dieter Raethel

Dieter Goerlich

Friedrich Widemann

Bernhard Umlauf

Guenter Kahnau

Wilfried Meiler

Richard Kohse

Christof Schumacher

Wilfried Renovanz

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.

Fuel preheating device for a heater

A water type heater, in particular a vehicle auxiliary heater having a temperature safety mechanism, intended to prevent overheating damage to temperature-sensitive parts of the heater, that utilizes a contact sensor that is in heat conducting connection with the heat exchanger. As a heat conducting connection, a direct physical contact between the heat exchanger and a water jacket casing of the heater can be utilized that is, preferably, achieved with the aid of a projection, and optionally, a diametrically opposite projection acting as countersupport. In a modified embodiment, an elastic body that conducts heat well can be placed in a compressed state between the jacket casing and the heat exchanger. The contact sensor then lies against the outer surface of the casing as the temperature safety mechanism. The elastic body that conducts heat well is suitably made in the form of a disk made of a graphite material. In other embodiments, the contact sensor can be spring-mounted or at least a head part thereof can be elastically deformable. In this way, the contact sensor can extend into direct engagement with the heat exchanger without being adversely affected by thermal expansion effects experienced by the heat exchanger and jacket casing during operation of the heater.

Heater, in particular vehicle auxiliary heater, with a temperature

In an exhaust gas pipe of a diesel engine, a particle separator serving for reduction of the particle emission of the diesel engine by exhaust gas aftertreatment, a burner by which the particle separator can be regenerated by means of hot fuel gases delivered by the burner unit, the burner unit is so placed that, even in the case of leaks occurring at a flap valve for shutting off of the fuel gas line, no impairment of the operation of the burner is to be feared. For this purpose, upstream from the burner, a blower may be installed, which constantly provides air to the burner unit and the space of the fuel gas line between the flap valve and the burner unit, the air being discharged from the space into the environment by a vent pipe. In this way, exhaust gases, which leak past the closed flap valve into the fuel gas line, do not reach the burner and are discharged by the vent pipe into the enviroment. Alternatively, a suction blower can be placed in a vent pipe branching off from the space between the flap valve and the burner unit in the fuel gas line, this blower causing venting of the space, when the separator is not being regenerated and the flap valve is closed. According to another alternative embodiment, a bypass pipe goes from the space between the flap valve and the burner unit, into a section of the exhaust gas pipe located downstream from the separator. The discharge area of this bypass pipe is designed as an injector or ejector, so that a negative pressure is produced in the bypass pipe by which the space in the fuel gas line is vented.

Particle separator arrangement in an exhaust pipe of a diesel engine

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Mittelstetten, Germany

Dieter Raethel