Delphi Technologies, Inc.

Other

Michael J Steckler

Malcolm James Grieve

Kenneth M Simpson

Stephen F Majkowski

Carelton Williams

Andrew Paul Bagnasco

David Howard Burke

Sergio Quelhas

Steve L Melby

Derk Geurts

An improved method of testing for evaporative emission system leaks monitors vacuum decay in a closed system so that the effects of fuel tank expansion during the test interval are minimized. In a first embodiment pass/fail criteria are established in terms of the time required for the system pressure to decay by a calibrated amount for a predetermined leak size. A leak at least as large as the predetermined leak is detected if the measured time is shorter than a calibrated time. The effects of fuel tank expansion are minimized because the changes in fuel tank volume occur primarily due to the pressure differential across the tank, as opposed to the leak size, and the changes that occur during the test are essentially the same for any leak size under consideration. In a second embodiment, the pass/fail criteria are established in terms of the change in pressure that occurs in the calibrated time; a leak at least a large as the predetermined leak is detected if the measured change in pressure is larger than the calibrated pressure amount.

Leak detection method for an evaporative emission system including a flexible fuel tank

The present invention relates a method of detecting leaks and blockages in a fuel system. The leaks are detected using a RAMPOFF mode and a TANK mode. The RAMPOFF mode modifies the evaporative diagnostic purge logic to increase the ramp down rates of the evaporative purge duty cycle to aggressively shut off the purge solenoid valve for tests used to detect leaks as small as 0.02 inches in diameter. The TANK mode modifies the evaporative diagnostic purge logic to support aggressive purging requirements for tests used to detect larger leaks of greater than 0.04 inches in diameter. The MASS FLOW mode modifies the evaporative diagnostic purge logic to hold a constant purge mass flow rate necessary to detect blockages across a vent solenoid valve. The RAMPOFF mode, TANK mode, and MASS FLOW modes support evaporative diagnostics that are run continuously within a fuel system when acceptable engine operating conditions are present.

Enhanced vacuum decay diagnostic and integration with purge function

A control method for a direct injection gasoline engine operable in stratified or homogenous combustion modes and having a fuel vapor purge system estimates the hydrocarbon concentration of purge vapor during open loop fuel control in the stratified combustion mode, and controls the fuel injection quantity and the combustion mode based on the estimated concentration. The hydrocarbon concentration of the purge vapor is estimated during open-loop fuel control by measuring the air/fuel ratio error during steady state operation with no fuel vapor purging, and using such air/fuel ratio error to normalize the air/fuel error observed during steady state operation with purge control. The fuel injection quantity is compensated for the estimated purge vapor concentration, and engine combustion mode is determined in part based on a comparison of the estimated concentration with a calibrated threshold.

Control method for a direct injection gas engine with fuel vapor purging

A zero emissions fuel system includes a fuel tank fluidly interconnected with a fuel vapor containment and absorption canister. The canister is further interconnected with an engine intake manifold via a purge solenoid valve that controls the extent to which a vacuum in the intake manifold affects the canister. The canister is also interconnected with the ambient environment via at least one selectively operable valve. During normal operation of the engine, the purge solenoid valve allows the intake manifold to draw fuel vapor from the canister for consumption by the engine. At a predetermined vacuum pressure, the at least one valve opens, thereby allowing outside air to flow into the system through the vacuum relief valve to facilitate purging of the canister.

Vacuum based fuel system

An improved method of diagnosing evaporative emission system leaks at engine idle, wherein the system is closed and drawn down to a sub-atmospheric pressure early in a driving cycle prior to the achievement of an idle condition appropriate for leak testing. When the test enabling conditions other than engine idle are met, the system vent is closed, and the purge valve is modulated to regulate the fuel tank pressure at a sub-atmospheric value substantially equivalent to the leak test pressure to be used at engine idle. When engine idle is achieved, the purge valve is closed, and the leak test is conducted with little or no delay. The time required to conduct the leak test is improved because the system pressure is at or near the test pressure when the engine idle condition is achieved, and at the same time, the reliability of the leak test data is improved because vapor generation equilibrium in the fuel tank is more nearly achieved when the leak test is initiated.

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Highland, MI, United States of America

Michael J Steckler