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Method to Operate Fuel Operated Heater During Decel Fuel Shut Off Mode Disclosure Number: IPCOM000244166D
Publication Date: 2015-Nov-18
Document File: 1 page(s) / 237K

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Method to Operate Fuel Operated Heater During Decel Fuel Shut Off Mode

- In California, a CARB mandate exists that limits engine idling for fleets. Specifically, vehicles with weight > 10,000 cannot idle an engine for more than 5 minutes at a time. This is to reduce tailpipe emissions and improve air quality. During cold weather, loss of engine power means loss of cabin heat since engine heat is used to warm up the cabin. Fuel Operated Heaters (FOH) are typically installed in vehicles to remedy the loss of engine combustion. The FOH uses gasoline from the car fuel tank and a glow plug to ignite it. FOH heats up the coolant inside the engine/cabin without having to start the engine and idle it. This saves fuel by a ratio of 1/8 vs idling. Once the vehicle's engine combusts again, the FOH turns off. Note that Start/Stop or Hybrid engines may actually turn on the engine if heat is demanded. There are also vehicle driving conditions known as Decel Fuel Shut Off (DFSO) in which a vehicle can coast to a stop or is motored by gravity (such as a long downhill drive) while not combusting. During a DFSO event, there is no engine combustion and hence waste heat cannot be used to warm up the cabin. This can be problematic in cold climates when driver demands heat. Turning on the full engine combustion is wasteful as it consumes a lot of fuel.


Our method uses the FOH during a DFSO mode when engine is not combusting (DFSO). This provides heat to the cabin without turni...