Protective Cover Snap-Fastening for Vibration-Resistant Rotary Machines
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Solution Overview
Problem
The existing snap-fastening mechanism for protective covers in rotary electrical machines, such as alternators, is not robust and suffers from wear and detachment due to vibrations, making it difficult to reuse the cover after dismantling.
Innovation Solution
A protective cover with a screw that includes a retention groove and a shoulder to secure flexible tongues, preventing excessive wear and allowing for easy dismantling without damage, enabling secure snap-fastening and reusability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the protective cover is secured by snap-fastening with tongues on threads, then the cover can be easily attached, but the plastic wears and the tongues detach due to vibrations
Solution Approach 1:
A retention groove is introduced as an intermediary element between the tongue and the threaded portion of the screw. The groove receives and retains the tongue, preventing it from sliding along the threads during vibration, while still allowing for easy snap-fastening attachment.
Solution Approach 2:
The retention groove is designed beforehand to accommodate the tongue, providing a pre-prepared retention mechanism that prevents wear and detachment before vibrations can cause damage. This anticipatory design prevents the harmful effect of vibration-induced wear.
2Ease of repair
If the cover is dismantled for finishing operations, then maintenance can be performed, but the tongues break and the cover cannot be reused
Solution Approach 1:
The retention groove acts as a protective intermediary that holds the tongue in place during dismantling operations. The tongue can be removed from the groove for maintenance, and the groove ensures the tongue is properly retained upon reassembly, enabling cover reuse.
Solution Approach 2:
The design allows the cover to be temporarily disassembled for maintenance (discarding the assembled state) and then recovered by reinserting the tongues into the retention grooves, restoring the secure attachment and enabling reuse.
3Device complexity
If the tongues are subjected to friction with threaded areas, then the screw can secure both the module and cover, but excessive wear leads to detachment
Solution Approach 1:
The screw is segmented into two distinct functional portions: a threaded portion for securing the electronic control module to the rear bearing, and a smooth retention groove portion for retaining the tongues of the protective cover. This segmentation prevents the tongues from contacting the threaded area, eliminating wear while maintaining integrated securing functionality.
Solution Approach 2:
The retention groove serves as an intermediary structure that separates the tongue retention function from the threaded securing function. This intermediate structure prevents direct contact between the tongue and threaded portion, eliminating friction-induced wear while maintaining both securing functions.
Data Source
AI summary
The invention relates mainly to a rotary electric machine for a motor vehicle, having: —a casing (11), —an electronic assembly (47) mounted on the casing, —a protective cover (50) positioned around the electronic assembly (47), and —a screw (55) that extends along an axis (X′) and allows the cover (50) to be fastened to the casing (11) and/or electronic assembly (47). The protective cover (50) has at least one opening that forms a fastening zone into which there extends at least one tongue (56) delimiting a central opening (57) for the screw (55) to pass through. The screw (55) has a screw head (70) and a retaining groove (71) such that the tongues (56) are housed in said groove (71).