Fuel Tank System Tightness Testing via Compressor Parameters
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Solution Overview
Problem
Current methods for checking the tightness of fuel tank systems in internal combustion engines cannot effectively assess the tightness of all sections, particularly the sections beyond the tank ventilation valve and check valve, leading to potential uncontrolled escape of fuel vapors into the environment.
Innovation Solution
A method utilizing a compressor integrated into the scavenging air line, which generates defined pressure levels and compares operating parameters such as compressor drive speed and electrical current with setpoint values to determine the tightness of sections within the fuel tank system, ensuring that gases flow only through the compressor, and using shut-off valves to isolate sections for testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pressure sensor is arranged between the tank ventilation valve and the check valve to measure pressure changes, then the tightness of the section between these valves can be checked, but the tightness of the remaining sections of the tank ventilation system cannot be checked
Solution Approach 1:
The scavenging air line is divided into two separable sections: a first section between the fuel vapor filter and the compressor, and a second section between the compressor and the shut-off valve. This segmentation allows the compressor to be used for testing different sections independently, enabling comprehensive tightness checking of the entire system rather than just one section.
Solution Approach 2:
The compressor is designed to serve multiple functions: it acts as both a scavenging device for the fuel vapor filter and as a testing device for checking tightness of different sections of the ventilation system. By utilizing the compressor's ability to generate pressure changes and measure operating parameters, the same component performs both operational and diagnostic roles, increasing system versatility without adding separate testing equipment.
2Measurement precision
If the compressor is used to generate defined pressure levels for testing, then precise determination of tightness is enabled, but additional components like shut-off valves are required to isolate sections
Solution Approach 1:
The shut-off valve is integrated into the existing scavenging air line rather than being added as a separate testing component. This integration allows the valve to serve dual purposes: controlling the scavenging air flow during normal operation and isolating sections during tightness testing. The merging of testing functionality into existing components achieves precise measurement capability without significantly increasing overall system complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method allows for precise determination of tightness in various sections of the fuel tank system, including the scavenging air line and ventilation line, enabling early detection of leaks and preventing fuel vapor escape into the environment, thus ensuring compliance with emission regulations.
Implementation Method 1
A method utilizing a compressor integrated into the scavenging air line, which generates defined pressure levels
Implementation Method 2
integrating a fuel vapor filter, usually in the form of an activated carbon filter, into the ventilation line, which absorbs the fuel vapors
Implementation Method 3
the negative pressure prevailing in the region of the opening of the scavenging air line in the fresh-gas line can temporarily draw in ambient air via an ambient opening of the fuel vapor filter
Data Source
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AI summary
The invention relates to a method for testing the sealing tightness of a fuel tank system of an internal combustion engine, wherein the fuel tank system comprises: a fuel tank (10); a fuel vapor filter (14), which is connected in a fluid-conducting manner to an environment opening (62); a venting line (12), which leads from the fuel tank (10) to the fuel vapor filter (14), a purge air line (16), which leads from the fuel vapor filter (14) to a fresh gas tract (18) of the internal combustion engine; a compressor (64) integrated into the purge air line (16); and a shutoff valve (60), which is integrated into the purge air line (16) and which is arranged between an opening (50) of the purge air line (16) into the fresh gas tract (18) and the compressor (64), is characterized in that sufficient sealing tightness and insufficient sealing tightness are distinguished by a comparison of at least one value or value curve of a parameter that corresponds to an operating parameter of the compressor (64) or to the pressure in at least one section of the purge air line (16) that should be tested, said value or value curve being determined in a defined operating state of the fuel tank system, with an associated set point value or set point value range, which represents said operating state and which corresponds to sufficient sealing tightness.