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OnBoard Control Modules Rain Diagnostic System for Evap Leak Detection Utilizing Smart Windshield Washer System

IP.com Disclosure Number: IPCOM000239422D
Publication Date: 2014-Nov-05
Document File: 1 page(s) / 245K

Publishing Venue

The IP.com Prior Art Database

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OnBoard Control Modules Rain Diagnostic System for Evap Leak Detection Utilizing Smart Windshield Washer System

Vehicles sold in North America are required to perform Evap leak diagnostics. Federal states require leak detection on the order of 0.04" in diameter leaks whereas green states require leaks on the order of
0.02". A common method for detecting small Evap leaks is Engine Off Natural Vacuum (EONV). The method relies on heat rejection from a combusting engine to warm up the bulk fuel. At key off, the Evap system is sealed and the ensuing pressure or vacuum build indicates if a system is sealed or leaking. Rain is a big noise factor which negates heat rejection. Driving in the rain and running EONV can result in false failures. Some high end vehicles have rain sensors, but the sensors are not OBD components and cannot be used to enable OBD diagnostics. A method of inferring rain for every vehicle is desirable to boost Evap leak detection robustness against rain.

Method

This method uses wiper actuation and wiper motor load current to infer a rain event.When rain strikes the windshield, a typical driver responds by turn on the wiper system.Running the wiper mechanism adds a mechanical load on the wiper's motor. The added mechanical load is a function of wiper speed, blade-windshield friction, effective mass of the wiped fluid (water, snow, washer spray). Thismethod classifies the wiper mechanical loads based on the physical properties of the snow, rain, and washer fluid...