Fuel Pump Capacitance Detection Using Housing Electrode
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Solution Overview
Problem
In fuel pumps with limited space in fuel tanks, the detection accuracy of capacitance related to fuel properties, such as alcohol concentration, is compromised due to the inability to secure a large surface area for the detection electrodes, leading to reduced efficiency in both capacitance detection and pressure regulation.
Innovation Solution
A fuel pump design that includes a pump main body within the fuel tank, a housing electrode covering the pump, and an outside electrode positioned externally, forming a gap to enhance capacitance detection accuracy, with a filter casing and control system to stabilize the electrode positions and estimate alcohol concentration for precise pressure regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the fuel property detection device is arranged externally on the side of the fuel pump, then the pump function can be performed, but the space in the fuel tank is insufficient to secure a large surface area for the detection electrodes
Solution Approach 1:
The detection device is merged with the pump housing, where the housing itself serves as one electrode (housing electrode) and an outside electrode is positioned adjacent to it. This integration eliminates the need for separate external detection device space while maintaining a large effective electrode surface area through the housing structure.
Solution Approach 2:
The pump housing serves dual functions: it provides structural containment for the pump mechanism and simultaneously acts as an electrode for capacitance detection. This multi-functionality allows the same space to serve both mechanical and sensing purposes, maximizing the use of limited fuel tank space.
2Measurement precision
If the detection electrodes are arranged in a double cylindrical shape with a gap, then capacitance detection can be performed, but the space required increases and reduces the available volume in the fuel tank
Solution Approach 1:
The housing electrode is formed by the pump housing itself, integrating the detection electrode structure with the existing pump components. This eliminates the need for additional space-consuming separate electrode housings while maintaining the capacitive sensing gap structure for accurate detection.
Solution Approach 2:
The capacitive detection is implemented using the radial dimension of the cylindrical pump housing, creating a gap between the housing electrode (outer surface) and the inside electrode (inner surface). This radial arrangement allows effective detection surface area without increasing the axial or radial footprint beyond the pump's existing dimensions.
3Measurement precision
If the surface area of the detection electrodes is increased to improve detection accuracy, then the capacitance detection precision improves, but the device complexity and space requirements increase
Solution Approach 1:
The pump housing serves as the housing electrode, eliminating the need for a separate detection device structure. This reduces overall device complexity while providing a large effective electrode surface area through the housing's extended surface, thereby improving detection accuracy without adding structural complexity.
Solution Approach 2:
The pump housing automatically serves as the detection electrode without requiring additional components or structures. The existing housing geometry is utilized for capacitance sensing, reducing device complexity while maintaining or enhancing detection capabilities through the inherent surface area of the housing.
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
The design significantly increases the detection accuracy of capacitance and pressure regulation by securing a large surface area for the gap between electrodes, allowing for stable and precise estimation and control of alcohol concentration and discharge pressure.
Implementation Method 1
A gap is formed between the outside electrode and the housing electrode to give the capacitance
Data Source
AI summary
A fuel pump has a pump function of sucking fuel in a fuel tank and discharging fuel, and a detection function of detecting a capacitance correlated to a concentration of alcohol in fuel in the fuel tank. The fuel pump includes a pump main body that is received in the fuel tank to perform the pump function, a housing electrode that covers the pump main body in the fuel tank, and an outside electrode that is located outside of the housing electrode in the fuel tank. A gap is formed between the outside electrode and the housing electrode to give the capacitance.