Fuel Tank Ventilation Valve Segmentation for Actuation Force Reduction
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Solution Overview
Problem
Existing ventilation arrangements for vehicle fuel tanks require three valves to maintain increased internal pressure, which demand high actuating forces and large volumes due to high flow resistances, making them inefficient and bulky.
Innovation Solution
The ventilation arrangement divides the switching movement of the electromagnetically switchable valve into two path elements, with a pilot valve having a small cross section to reduce energy expenditure, allowing for a smaller, more compact drive that can achieve arbitrary pressure settings without undershooting, and utilizes existing design elements to create a compact unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a single electromagnetically switchable valve with large flow cross section is used to maintain pressure in the fuel tank, then the pressure control function is achieved, but the actuating force required becomes very high and the drive volume becomes large
Solution Approach 1:
The valve is segmented into a main valve and a pilot valve. The main valve has a large flow cross section for pressure control, while the pilot valve has a small cross section that is easier to actuate. The pilot valve controls the actuation of the main valve, allowing the large main valve to be opened with minimal force by using the small pilot valve to release the holding force rather than directly overcoming the full spring force.
Solution Approach 2:
The pilot valve acts as an intermediary between the electromagnetic drive and the main valve. Instead of the electromagnetic drive directly actuating the large main valve, it first actuates the small pilot valve, which then triggers the main valve opening through pressure differential and spring force assistance.
2Stress or pressure
If a single electromagnetically switchable valve with large flow cross section is used for ventilation, then pressure control is achieved, but the drive installation volume becomes large
Solution Approach 1:
The valve assembly is segmented into main valve and pilot valve components. The pilot valve mechanism is integrated into the main valve structure, allowing the drive to be compact while still controlling the large main valve through the pilot mechanism.
Solution Approach 2:
The pilot valve is nested within the main valve structure. The pilot valve components are positioned inside or integrated with the main valve body, allowing the entire valve assembly to occupy less space while maintaining the functionality of both valves.
3Stress or pressure
If three separate valves are used to maintain increased pressure in the fuel tank, then pressure control and tightness are achieved, but the device complexity increases
Solution Approach 1:
Multiple valve functions (pressure relief valve, vacuum valve, and electromagnetically switchable valve for refueling) are merged into a single integrated valve assembly. The main valve and pilot valve work together as one unit, reducing the number of separate components and simplifying the overall system while maintaining all required functions.
Solution Approach 2:
The integrated valve assembly performs multiple functions: pressure relief through the pressure relief valve, vacuum prevention through the vacuum valve, and controlled ventilation during refueling through the electromagnetically switchable main and pilot valves. This multi-functional design eliminates the need for three separate valve systems.
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 design reduces the power and installation space requirements for the drive, enabling efficient and adjustable pressure management within the fuel tank while maintaining a balanced adsorption and desorption of hydrocarbon components in the activated charcoal filter.
Implementation Method 1
vapors escape because of vapor pressure differentials relative to the surrounding atmosphere, which are conducted through an activated charcoal filter inserted in a ventilation line, which is intended to adsorptively bind hydrocarbon components
Implementation Method 2
This pressure relief valve establishes a continuous connection between the head space and the surrounding atmosphere when an overpressure or a maximum pressure occurs
Data Source
AI summary
A ventilation arrangement for the head space of the fuel tank of a vehicle comprises a switchable main valve intended for adjusting an arbitrary pressure in the head space of the tank. By way of the opening position of the main valve, a connection between a connection (5) intended for connection to the head space and a connection (6) intended for connection to the surrounding atmosphere is established, wherein the main valve is assigned a pilot valve, which opens during a first path element of a switching movement, wherein the main valve only opens following this first path element. Because of the small cross section of the pilot valve and the pressure relief that materialized through its opening, the switching power can be reduced and a smaller size drive can be employed.