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Fuel Rail Depressurization System For Reducing Evaporative Emissions From A Vehicle

IP.com Disclosure Number: IPCOM000009681D
Publication Date: 2002-Sep-10
Document File: 1 page(s) / 40K

Publishing Venue

The IP.com Prior Art Database

Abstract

When a vehicle having an engine fueled by a gaseous fuel, such as compressed natural gas, hydrogen, or liquid petroleum gas, is inactive, the high residual pressure in the fuel rail inevitably bleeds down through the fuel injectors during the inactive period. Another factor leading to further fuel leakage across the injectors is the diurnal temperature changes that cause a change in system pressure. Fuel leaked through the injectors into the intake manifold escapes to the atmosphere via the air induction system.

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Fuel Rail Depressurization System for Reducing Evaporative Emissions From a Vehicle

When a vehicle having an engine fueled by a gaseous fuel, such as compressed natural gas, hydrogen, or liquid petroleum gas, is inactive, the high residual pressure in the fuel rail inevitably bleeds down through the fuel injectors during the inactive period.� Another factor leading to further fuel leakage across the injectors is the diurnal temperature changes that cause a change in system pressure. Fuel leaked through the injectors into the intake manifold escapes to the atmosphere via the air induction system.�

Automotive vehicles are subject to evaporative emission standards and are tested for compliance in a 2 or 3-day diurnal standard test procedure.� Gaseous fuel leakage through injectors is a significant fraction of the total level of evaporative emissions.

The present idea is to reduce leakage through the injectors by dropping the pressure in the high-pressure fuel rail.� This is accomplished by evacuating the pressure in the rail into a relatively large reservoir, with respect to the rail volume.� The combined reservoir and rail volume enables the fuel to approach atmospheric pressure, thereby significantly reducing the pressure difference across the injector tips, thereby reducing the potential for leakage.

Another aspect of the present idea is that the reservoir is brought into communication with the intake manifold during engine operation, providing access to manifold vacuum.� In this way, the purged reservoir pressure is made to be less than atmospheric, further improving the effectiveness of the system.

The inventive system, as shown in Figure 1, comprises a storage reservoir coupled to the...