Starter Metal Conductor with Fuse Function
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Solution Overview
Problem
Conventional starters face issues with abnormal current flow leading to short circuits and component breakage due to low melting point materials, and the risk of normal current causing fuse failure, which prevents engine starting.
Innovation Solution
A starter design featuring a metal conductor with a narrowed portion having a fuse function and higher electrical resistance than the field coil, connected upstream of the field coil to reliably cut off abnormal currents and prevent short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pigtail moves with the brush and comes close to nearby component, abnormal current flows causing the fused pigtail to contact the component and create short circuit
Solution Approach 1:
The narrowed portion acts as an intermediary protective element that sacrifices itself by fusing first, preventing the main current path from being compromised. It serves as a controlled weak point that protects the overall system from more severe failures.
Solution Approach 2:
The fuse function is extracted and concentrated into a specific narrowed portion of the metal conductor, separating this protective function from the main current-carrying path. This allows the fuse function to operate independently at a designated location away from critical components.
2Ease of manufacture
If a soft solder material with low melting point is used for the brush lead wire, then connection is achieved, but the lead wire may undergo fusing during normal current supply
Solution Approach 1:
Rather than using low melting point material throughout the entire lead wire, the invention creates a localized narrowed portion with specific properties. This localized approach provides the necessary fuse function while the rest of the conductor maintains appropriate properties for normal current carrying.
Solution Approach 2:
The metal conductor can be viewed as a composite structure with different sections having different properties - the narrowed portion with higher resistance for fuse function, and the main body with lower resistance for efficient current conduction during normal operation.
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
Effectively prevents breakage from abnormal currents and reduces the likelihood of current cutoff during normal operation, while avoiding unnecessary component additions and maintaining engine starting functionality.
Implementation Method 1
the metal conductor has a narrowed portion endowed with a fuse function and having a small sectional area... the metal conductor is endowed with a fuse function and is composed of a material having a larger electrical resistance than the field coil
Data Source
AI summary
Provided is a starter which reliably cuts off any abnormal current caused to flow through the motor and which can reduce the possibility of current cutoff in the case of normal supply current. According to the present invention, a starter includes: a motor having a field coil; and an electromagnetic switch for supplying an electric current from a battery to the motor to start an engine through a pinion gear, in which: a metal conductor is connected to an upstream side of the field coil to which the electric current is supplied; and the metal conductor has a narrowed portion endowed with a fuse function and having a small sectional area.