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LIQUID FUEL TEMPERATURE INFERENCE VIA FUEL PUMP COIL RESISTANCE MEASUREMENT AT KEY OFF

IP.com Disclosure Number: IPCOM000238397D
Publication Date: 2014-Aug-22
Document File: 1 page(s) / 247K

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The IP.com Prior Art Database

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LIQUID FUEL TEMPERATURE INFERENCE VIA FUEL PUMP COIL RESISTANCE MEASUREMENT AT KEY OFF

Vehicles sold in North America are required to perform Evap leak detection as part of OBDII requirements. Green states are required to monitor for 0.02" leaks as part of the Clean Air Act Section 177 (CAA). In MY2017, all states have to perform 0.02" leak tests.For regular gasoline engines, a technique called Engine Off Natural Vacuum (EONV) is used to perform leak detection. EONV relies on heat rejection from a combusting engine to reach the tank and warm the bulk fuel during driving.At key off, the Powertrain Control Module (PCM) stays alive and executes Evap leak detection routine if ample heat was rejected into bulk fuel. Heat rejection into the fuel tank is typically inferred since it is difficult to quantify it. OEMs use various methods to infer heat rejection such as the distance traveled, air mass summation, or injected fuel summation. These heat rejection inference methods are not robust and can be prone to error. A vehicle can travel for miles without engine combusting (HEV, Decel Fuel Shut off, Cylinder Deactivation, etc.). Ultimately, the best indicator that heat was rejected into the liquid fuel is by measuring the fuel temperature after key off. However, adding a temperature sensor is costly. Ideally, a temperature inference is a better method.

Method

The method infers the liquid fuel temperature after key off before EONV starts to execute and when the fuel pum...