Conductive Plastic Water Sensor Brass Pin Contact
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Solution Overview
Problem
Water level sensors in fuel filters face issues with reduced electrical conductivity due to the formation of an isolating 'spray skin' during the plastic injection molding process, which affects the connection with other components.
Innovation Solution
A sharp-edged metal pin, such as a brass pin, is pressed into the electrically conductive plastic water level sensor to tear open the surface and create a reliable electrical contact, eliminating the spray skin and enabling a secure connection to a printed circuit board.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a smooth surface is used in the plastic injection mold to create a spray skin, then the injection molding process is simplified, but the electrical conductivity on the surface of the water level sensor is adversely affected
Solution Approach 1:
The harmful spray skin layer is removed by pressing a metal element with a sharp-edged fastening contour into the plastic, which mechanically extracts or eliminates the isolating surface layer to expose the conductive fibers underneath
Solution Approach 2:
The plastic material is pre-formed with conductive fibers embedded throughout, including the surface layer, so that when the spray skin is removed, the conductive fibers are immediately exposed and available for electrical connection without requiring additional treatment
2Reliability
If a screw connection is used to connect the water level sensor to the printed circuit board, then the connection is secure, but the space requirement increases significantly
Solution Approach 1:
The traditional screw connection mechanism is replaced with a press-in connection using a metal element with a sharp-edged fastening contour that is pressed directly into the plastic, eliminating the need for threads and reducing the connection diameter from approximately 8 mm to 2-3 mm
Solution Approach 2:
The connection method changes from a threaded mechanical fastening system to a direct press-in system, fundamentally altering the geometric parameters of the connection interface to achieve both security and compactness
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 provides a reliable, efficient, and space-saving electrical connection between the water level sensor and the printed circuit board, enhancing the precision and cost-effectiveness of water level detection in fuel filters.
Implementation Method 1
The brass element has the previously described sharp-edged, in particular fir-shaped or sawtooth-shaped, fastening contour, by means of which it is pressed into the electrically conductive plastic of the water level sensor and thereby tears the latter open
Implementation Method 2
which provides information about the water level in the water collection chamber. The electrically conductive poles can be designed, for example, in the form of lines, with electrically conductive plastics having, for example, electrically conductive fibers, such as carbon fibers in particular
Data Source
Figure 1~3
AI summary
The invention relates to a water level sensor device (5) for a fuel filter (1), comprising a printed circuit board (6) and a water level sensor (4) made of an electrically conductive plastic (7), the water level sensor (4) being connected to the printed circuit board (6) via an electrically conductive metal element (8), in particular a brass element (8'). The metal element (8), in particular the brass element (8'), is connected to the water level sensor (4) via a press-fit assembly (9).