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WIND INFERENCE IN A STATIONARY VEHICLE TO IMPROVE OBD MONITOR ROBUSTNESS

IP.com Disclosure Number: IPCOM000234691D
Publication Date: 2014-Jan-28
Document File: 1 page(s) / 222K

Publishing Venue

The IP.com Prior Art Database

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WIND INFERENCE IN A STATIONARY VEHICLE TO IMPROVE OBD MONITOR ROBUSTNESS

Vehicles sold in North America are required to perform Evap Leak Diagnostics. For green states, a leak size of 0.02" needs to be detected. Since 0.02" leak is very small, most OEMs perform the 0.02" leak detection in a vehicle static condition to reduce noise factors from sloshing fuel, vehicle dynamics, etc… Typically, natural vacuum methods are used at key off to detect for 0.02" leaks. Alternatively, PCM is awakened hours after shutdown to perform Evap leak detection by using a vacuum pump. One noise factor that can result in a 0.02" leak monitor setting false failures is an excessive wind condition. When the wind blows, it can accelerate the cooling effect inside the fuel tank. A 0.02" leak or smaller will go undetected. Inability to demonstrate monitor ability to detect failures can cause vehicle recalls. Ideally, an excessive wind condition needs to be detected and the OBD monitor needs to either compensate for it or abort execution.

Method

The majority of 0.02" Evap leak detection methods used by various OEMs occur after key off when the vehicle is stationary. The novelty of the invention is to infer wind conditions in a stationary vehicle and use it as an input to the OBDII Evap leak diagnostics. The method utilizes the existing ambient temperature sensor located outside the vehicle to infer wind existence. Any sudden temperature spikes or perturbations in the temperature sensor,...