Tank Venting Tightness Verification Without Pressure Sensor
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Solution Overview
Problem
Current methods for verifying the tightness of a tank venting system in motor vehicles are either time-consuming or require a pressure sensor, which increases costs.
Innovation Solution
A method that reduces verification time without using a pressure sensor by opening the tank venting valve to generate negative pressure, measuring the duration until pressure exceeds a switching pressure, and assessing tightness based on this duration, with optional regulation of valve openings and use of a membrane to control pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pressure sensor is used to monitor pressure continuously, then measurement precision and reliability are improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the continuous pressure monitoring function and replaces it with a simple bistable pressure switch that only detects whether pressure exceeds a predefined threshold. This eliminates the need for expensive pressure sensors while maintaining sufficient measurement capability for the tightness verification application.
Solution Approach 2:
The patent employs a inexpensive bistable pressure switch instead of a costly pressure sensor. The pressure switch is a simple, low-cost component that provides adequate functionality for detecting pressure threshold crossings during the verification process, significantly reducing system cost and complexity.
2Device complexity
If the engine coolant temperature is monitored until it drops sufficiently, then tightness verification can be performed without a pressure sensor, but the verification time increases significantly
Solution Approach 1:
The patent performs preliminary action by actively generating the required negative pressure condition through controlled valve operations before the tightness verification measurement begins. This eliminates the need to wait for natural temperature-driven pressure changes, reducing verification time from hours to seconds while maintaining the ability to perform verification without expensive pressure sensors.
Solution Approach 2:
The patent uses periodic action by repeatedly opening and closing the tank venting valve to generate oscillating pressure conditions. This periodic valve actuation creates multiple pressure cycles that allow the bistable pressure switch to detect tightness characteristics through threshold crossings, enabling rapid verification without waiting for temperature changes.
3Loss of time
If the tank venting valve is opened to generate negative pressure rapidly, then verification time is reduced, but control complexity increases
Solution Approach 1:
The patent implements feedback by using the bistable pressure switch to detect when the pressure has reached the required negative threshold condition. The control unit receives feedback from the pressure switch about threshold crossings and uses this information to determine when to close the tank venting valve, enabling rapid and controlled pressure generation without complex control mechanisms.
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 rapid verification of tank venting system tightness without a pressure sensor, reducing costs and time, and provides a clear indication of leaks by measuring pressure build-up rates.
Implementation Method 1
a bistable pressure switch, the switching states of which indicate that the pressure in the tank venting system is above or below a predetermined switching pressure
Implementation Method 2
the tank venting valve is opened so that the negative pressure in the intake pipe can disperse in the tank venting system
Implementation Method 3
a stop valve for sealing the tank venting system such that it is air-tight relative to an atmosphere prevailing outside the motor vehicle
Data Source
AI summary
In a method for verifying the tightness of a tank bleeding system with a tank bleeding valve, a stop valve for air-tightly closing the tank bleeding system relative to an atmosphere prevailing outside the motor vehicle, and a bistable pressure switch whose switched condition indicates whether a predefined switching pressure is exceeded or not reached in the tank bleeding system, in order to be able to determine the tightness of the tank bleeding system without using a pressure sensor, the following steps are carried out: waiting until the vehicle speed drops below a certain threshold; opening the tank bleeding valve; closing the tank bleeding valve when a negative pressure has been attained which lies below the switching pressure; measuring the duration from the time an initial pressure lies below the switching pressure until the moment the switching pressure is exceeded again; and assessing the tightness is assessed based on the measured duration.