Aluminum Battery Box Isolation from Steel Chassis
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Solution Overview
Problem
Galvanic corrosion occurs between aluminum alloys and steel components in vehicles due to their dissimilar metal nature, leading to potential structural integrity and corrosion issues.
Innovation Solution
A structural enclosure design featuring aluminum rails with sleeves that have a predefined thickness, separating the aluminum rails from a steel body structure, and coated to prevent electrochemical contact, thereby inhibiting galvanic corrosion. The sleeves are either E-coated or have a multi-layer coating to ensure electrochemical isolation, and bolts are used to securely mount the rails to the steel structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If aluminum alloy components are used to reduce vehicle weight, then fuel efficiency is improved, but galvanic corrosion occurs when aluminum contacts steel components
Solution Approach 1:
The patent introduces plastic inserts and coating layers as intermediary materials between aluminum alloy components and steel fasteners. These intermediaries electrically isolate the dissimilar metals, preventing galvanic corrosion while maintaining the structural integrity and weight reduction benefits of aluminum alloy usage in vehicle bodies
Solution Approach 2:
The patent applies protective coatings and pre-installs plastic inserts on steel components before assembly with aluminum parts. This preliminary protective action prevents galvanic corrosion from occurring in the first place, rather than attempting to treat corrosion after it has started
2Strength
If dissimilar metal structures are used in vehicle construction, then design flexibility and strength are improved, but galvanic corrosion occurs at contact points
Solution Approach 1:
The patent employs plastic inserts and electrochemical coatings as intermediary layers between dissimilar metal components. These intermediaries maintain the structural strength benefits of using steel fasteners and aluminum body components while preventing direct electrical contact that would cause galvanic corrosion
Solution Approach 2:
The patent applies protective measures locally at specific contact points between dissimilar metals, such as threading plastic inserts into steel fasteners or applying coatings at interface areas. This localized approach provides corrosion protection exactly where galvanic corrosion would occur, while maintaining the overall structural integrity of the assembly
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 solution effectively prevents galvanic corrosion between aluminum and steel components by maintaining a defined separation and reducing contact areas, enhancing the structural integrity and corrosion resistance of vehicle components.
Implementation Method 1
aluminum alloys are galvanically anodic relative to steel and thus galvanic corrosion can occur when an aluminum alloy component comes into contact with a steel component in the presence of an electrolyte
Implementation Method 2
the at least one aluminum rail is electrochemically isolated from the at least one sleeve and/or the steel body structure such that galvanic corrosion between the at least one aluminum rail, the at least one sleeve and the steel body structure is inhibited
Data Source
AI summary
A structural enclosure includes a pair of aluminum rails with an upper wall and a lower wall spaced apart from the upper wall, a plurality of sleeves extending into and captured within the aluminum rails, and each of the plurality of sleeves having a head with a predefined thickness disposed on an outer surface of the aluminum rails and configured to separate the outer surface of the aluminum rails from a steel vehicle chassis to which the aluminum rails are mounted. The structural enclosure can be an aluminum battery box for an electric vehicle and the aluminum battery box can be mounted to and electrochemically isolated from the steel vehicle chassis.