Browse Prior Art Database

EONV LEAK DETECTION ROBUSTNESS TO FUEL SLOSH METHOD

IP.com Disclosure Number: IPCOM000236164D
Publication Date: 2014-Apr-10
Document File: 1 page(s) / 219K

Publishing Venue

The IP.com Prior Art Database

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 67% of the total text.

Page 01 of 1

EONV LEAK DETECTION ROBUSTNESS TO FUEL SLOSH METHOD

Vehicles sold in North America market are required to capture fuel vapors and store them inside a carbon canister. Vehicles are also required to perform leak checking/diagnostics on the Evap system. For green states, leaks as small as 0.02" need to be detected. In MY2017, all states will adopt EPA Tier III regulations requiring 0.02" leak detection. Engine Off Natural Vacuum (EONV) is the 0.02" Evap leak detection strategy for many OEMs. EONV is based on heat rejection into the fuel tank from a combusting engine. At key off, the Evap system is sealed and the resulting pressure rise or vacuum build yields Evap system leak integrity results. One noise factor which can alter EONV pass/fail results is how the vehicle comes to a stop. If the vehicle comes to a harsh stop, or performs a radius turn before stopping, or stops on hilly terrain, the fuel sloshes inside the fuel tank. The issue is aggravated if the fuel is winter grade (high RVP). Fuel slosh causes a dramatic pressure rise inside fuel tank which results in alpha or beta errors.

Method

This system improves EONV robustness to fuel slosh by monitoring the fuel level indicator sensor(FLI) prior to key off. If the sensor shows significant fuel slosh prior to key off, the strategy does not seal the Evap system until the fuel slosh wave has dissipated and the pressure rise associated with the fuel slosh has subsided.Fuel slosh is typically calculated as ABS[ins...