Fuel Level Sensor Dissolvable Barrier Layer Fretting Protection
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Solution Overview
Problem
Fuel level sensors in fuel tank assemblies are prone to damage due to fretting between the wiper and resistor contacts during transportation, especially when the tank is empty, leading to premature wear and failure, and the current methods of protecting them are inefficient and require additional assembly steps.
Innovation Solution
A temporary barrier layer made of dissolvable materials like petroleum jelly or shellac resin is applied to the resistor board to prevent fretting between the wiper and resistive areas, which dissolves when the tank is filled with fuel, ensuring the sensor's operation and eliminating the need for separate assembly at the vehicle assembly plant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fuel level sensor is assembled to the fuel tank before transportation, then the sensor is protected from damage during transportation, but the manufacturing process becomes more complex and time-consuming
Solution Approach 1:
The patent applies preliminary action by pre-assembling the fuel level sensor to the fuel tank at the manufacturing plant before transportation. This allows the sensor to be protected during transit without requiring disassembly and reassembly at the vehicle assembly plant, thereby reducing manufacturing complexity while maintaining sensor protection.
Solution Approach 2:
The patent uses an intermediary substance (protective coating or damping material) applied to the resistor board or wiper contact areas. This intermediary layer prevents direct contact and fretting between the wiper and resistor contacts during transportation, protecting the sensor while allowing it to remain assembled to the tank.
2Reliability
If the fuel level sensor is disassembled from the fuel tank for transportation, then the sensor is protected from fretting damage, but additional assembly steps are required at the vehicle assembly plant
Solution Approach 1:
The fuel level sensor is pre-assembled to the fuel tank at the manufacturing plant before transportation. This preliminary assembly action eliminates the need for disassembly and reassembly at the vehicle assembly plant, saving time and preventing fretting damage through protective measures.
Solution Approach 2:
A protective intermediary layer is applied to the resistor board or wiper contact surfaces. This layer acts as a mediator that prevents direct friction and fretting between moving parts during transportation, allowing the sensor to remain assembled without risk of damage.
3Reliability
If a protective layer is applied to the resistor board, then fretting damage is prevented during transportation, but the protective layer must be removed or dissolved without affecting sensor operation
Solution Approach 1:
The protective layer is made from a material whose properties change under specific conditions - it is dissolvable in fuel. This parameter change allows the protective layer to be easily removed by simply filling the tank with fuel, eliminating the need for manual removal processes and ensuring ease of manufacture.
Solution Approach 2:
The protective layer is designed as a temporary, disposable element that serves its protective function during transportation and then dissolves harmlessly in fuel. This approach simplifies the manufacturing process by eliminating the need for complex removal 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
The dissolvable barrier layer effectively reduces fretting damage during transportation, allowing the fuel tank assembly to be transported complete with the fuel level sensor, ready for direct fitting to a vehicle, thus streamlining the assembly process and extending the sensor's lifespan.
Implementation Method 1
the temporary barrier layer (19) is formed of a material and is applied in a thickness such that it will dissolve when submerged in the fuel on a first filling of the fuel tank (3)
Data Source
Figure 1~2
Figure 3~4
AI summary
A fuel level sensor comprises a variable resistor assembly including a resistor card 13' with at least one resistive area 15, 16; and a wiper (10, Fig. 2) for sliding movement across the resistive area(s). To protect said sensor from damage during transportation within a fuel tank assembly, the at least one resistive area 15, 16 is covered by a temporary barrier layer 19 of material to prevent fretting between the contacts on the wiper 10 and the at least one resistive area. Barrier layer 19 is formed of a material, such as petroleum jelly or shellac resin, which is dissolvable in the fuel. The thickness of barrier layer 19 is sufficient to eliminate fretting during transportation, but thin enough to dissolve in fuel, which may be petrol or diesel, on a first filling of the tank.