Fuel Pump Terminal Insulation for Corrosion Resistance
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Solution Overview
Problem
Fuel pumps used in alcohol mixture fuels, which have high electric conductivity, face issues with electrochemical corrosion due to electrical short circuits between terminals.
Innovation Solution
A fuel pump design that includes insulative portions covering the base of terminals and a terminal support member with guide projections to prevent contact with fuel, reducing electrochemical corrosion and allowing easy assembly without interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If terminals are exposed in the fuel for conducting electricity to the motor section, then electrical conductivity is ensured, but electrochemical corrosion of the terminals occurs due to high electric conductivity of alcohol mixture fuel
Solution Approach 1:
An insulative portion is introduced as an intermediary component between the terminal and the fuel. This insulative portion selectively covers the terminal surface that would otherwise contact the fuel, preventing electrochemical corrosion while allowing the terminal to maintain its electrical conductivity function through non-fuel paths
Solution Approach 2:
The terminal surface is differentially treated: some portions are covered with insulative material to prevent corrosion, while other portions remain exposed to maintain electrical conductivity. This local differentiation allows the terminal to simultaneously achieve corrosion resistance and electrical functionality
2Object-affected harmful factors
If insulative portions are added to cover terminal base portions, then electrochemical corrosion is reduced, but assembly complexity increases due to additional components and fitting operations
Solution Approach 1:
The insulative portion is integrated with the discharge-side cover to form a single unified component. The insulative portion is fitted into a fitting hole formed in the discharge-side cover, merging the cover and insulator into one assembly unit that reduces the number of separate parts and simplifies the assembly process
Solution Approach 2:
The fitting hole for the insulative portion is pre-formed in the discharge-side cover during cover manufacturing. This preliminary preparation of the assembly structure allows for quick and easy installation of the insulative portion without requiring complex assembly operations or additional processing steps
Data Source
AI summary
A fuel pump includes a case member defining a fuel passage and a discharge-side cover connected to the case member and defining an outlet port. A pump section has an inlet port and is connected to the case member. A motor section is housed in the case member for driving the pump section. A positive electrode terminal and a negative electrode terminal are supported by an insulative terminal support member fixed to the discharge-side cover. Base portions of the positive and negative electrode terminals are covered by insulative portions. The insulative portions are fitted in fitting holes of the discharge-side cover. The discharge-side cover has guide portions on its inner surface. The terminal support member has engagement projections on opposite side walls thereof. The engagement projections are guided by the guide portions to restrict the discharge-side cover from rotating with respect to the terminal support member.