Saddle Fuel Tank Level Sensing for Pump Balance and Fuel Quantity
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Solution Overview
Problem
The existing fuel supply systems for road vehicles with internal combustion engines face challenges in accurately determining the fuel quantity and balancing the flow rates of low-pressure fuel pumps due to the absence of a connection pipe between the fuel tank's lower areas, leading to increased hydrocarbon emissions, mechanical vulnerabilities, and complex pump balancing.
Innovation Solution
A fuel supply system that employs three level sensors and control units to measure and calculate the fuel levels in separate areas of the fuel tank, allowing precise determination of the total fuel quantity and balancing the low-pressure fuel pumps by using conversion tables and feedback control to maintain target fuel pressure, eliminating the need for a connection pipe between the lower areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a connection pipe is provided to put the two lower areas in hydraulic communication, then fuel can flow freely between lower areas during transversal accelerations, but hydrocarbon vapour emissions increase and mechanical resistance decreases
Solution Approach 1:
The upper area acts as an intermediary space that enables indirect hydraulic communication between the two lower areas. During transversal accelerations, fuel can move from one lower area through the upper area to the other lower area, achieving the desired fuel redistribution without requiring a direct connection pipe that would increase emissions and reduce mechanical strength.
2Ease of operation
If a connection pipe is provided to put the two lower areas in hydraulic communication, then fuel distribution is improved during accelerations, but the number of components increases and mounting problems increase
Solution Approach 1:
The fuel tank is designed as a single integrated component where the upper area and two lower areas form one continuous hydraulic space. This merging of functions into a single structure eliminates the need for separate connection pipes and additional components, while still allowing fuel to distribute freely between lower areas during vehicle accelerations through the upper area.
3Object-generated harmful factors
If the connection pipe is eliminated, then hydrocarbon vapour emissions decrease and mechanical resistance increases, but fuel quantity determination becomes less precise
Solution Approach 1:
The upper area serves as an intermediary hydraulic space that connects the two lower areas indirectly. This configuration allows the system to eliminate the connection pipe (reducing emissions and improving mechanical strength) while maintaining the ability to determine fuel quantity accurately, as the upper area provides a reference level that sensors can use to calculate total fuel volume across all three areas.
4Object-generated harmful factors
If the connection pipe is eliminated, then hydrocarbon vapour emissions decrease, but access to the area under the fuel tank becomes more difficult
Solution Approach 1:
The connection pipe, which is the source of hydrocarbon vapour emissions and the obstacle to access, is completely extracted from the system. The fuel tank design relies on the internal geometry of the upper and lower areas to provide hydraulic communication, eliminating the external connection pipe that would interfere with access to the area under the fuel tank while maintaining the desired emission reduction.
5Productivity
If two low-pressure fuel pumps are used without a connection pipe, then fuel can be drawn from both lower areas, but balancing the flow rates becomes very complicated
Solution Approach 1:
The upper area acts as a hydraulic intermediary that balances the fuel supply system. By drawing fuel from both lower areas through the upper area, the system naturally equalizes pressure and flow conditions, making pump flow rate balancing much simpler compared to a system without this intermediary space.
Data Source
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AI summary
A fuel supply system (5) for a road vehicle (1) and having: a fuel tank (6), which is shaped like saddle due to the presence of a central saddle (10) and delimits an inner volume divided into an upper area (11), which is located above the central saddle (10), and two lower areas (12), which are located under the upper area (11) and are separated from one another by the central saddle (10); two low-pressure fuel pumps (7), which each suck from the bottom of a corresponding lower area (12); at least one high-pressure fuel pump (9), which receives fuel from both low-pressure fuel pumps (7); a level sensor (13) arranged in the upper area (11) and configured to measure a fuel level only in the upper area (11); and two level sensors (13), each arranged in a respective lower area (12) and configured to measure a fuel level only in the respective lower area (12).