Closed Loop Canister Purge Control System

Vapor purge estimation using a dual-mode observer

“…It is worth noting that alternative configurations of vapor purge systems exist wherein a bypass line is available between the fuel-tank vapor line and the vapor purge line as seen in the system of Sultan et al (1998). The system of Sultan et al (1998) is not considered in this paper.…”

“…Today's stringent tailpipe and evaporative emissions standards necessitate aggressive purge strategies to deplete the canister over the course of an emissions test cycle, and precise A/F control to achieve the high efficiencies required of the three-way catalyst (TWC). Methods employing vapor or pressure sensors have been proposed to estimate the amount of fuel and air contributed by the purge flow in order to mitigate the A/F disturbance as in Feldkamp, Yuan, and Jesion (2003) and Sultan, Kushion, Wind, Folkerts, and Mathhews (1998). In this paper, a control oriented model of the purge system is developed and a dual-mode observer is designed that permits increased purge flow without recourse to additional sensors.…”

Fuel–air ratio control for a spark ignition engine using gain‐scheduled delay‐dependent approach

“…In the past decades, considerable contributions have been presented by worldwide researchers and engineers. The authors [1–4] showed that disturbances of air and fuel mass flows into cylinders from vapour purge system can be estimated. The authors [5, 6] researched the oxygen sensor aging dynamics and parameters calibration, which can be applied to improve FAR feedback control performance.…”

Feed-forward control of purge flow in internal combustion engines

“…development of an engine-fueling compensation strategy that mitigates the effect of the purge flow on the A/ F control systems. Most of the literature is composed of studies focusing on the estimation of fuel vapor fraction (FVF) through various methods; previous studies [3][4][5][6][7][8][9][10][11][12] contain various proposed solutions. Presented herein is a summary of fundamental canister modeling and control studies.…”

“…These types of look-up tables cannot provide continuous estimation of the purge flow. 6 The purge flow estimation can be improved by using an upstream pressure sensor in the purge line as proposed in Sultan et al 7 Purge flow was estimated based on the Bernoulli's orifice equation; 13,14 for pressures above the critical pressure (in which the velocity of the flow has reached its maximum value possible, that is, speed of sound), the flow does not increase with pressure anymore (choked condition). In a canister purge application, this critical pressure itself is a function of fuel vapor concentration in the purge line, 7 due to the dependency of the specific heat ratio on the fuel vapor concentration; therefore, the accurate estimations of purge flow and FVF are coupled to one another.…”