Drive Unit Holder for Circuit Board Alignment and Protection
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Solution Overview
Problem
The assembly of drive units for electrically assisted vehicles is inefficient due to difficulties in aligning screw holes and the risk of damaging electronic circuit boards during the mounting process, particularly due to the reaction force from harnesses and the potential for tools to contact sensitive components.
Innovation Solution
A holder with tabs is used to fix the electronic circuit board, providing easy positioning and protection, along with insertion and screw guides that guide fasteners and prevent them from dropping, and a harness guide to keep wiring lines from being caught between components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the electronic circuit board is directly mounted to the housing, then the assembly process is simpler, but the positioning accuracy of screw holes deteriorates and the risk of tool damage to circuit components increases
Solution Approach 1:
The patent introduces a holder as an intermediary component between the electronic circuit board and the housing. The holder includes positioning protrusions that fit into positioning recesses on the circuit board, and guide holes that align with screw holes. This intermediary structure enables accurate positioning and screw hole alignment without requiring direct mounting, thus resolving the contradiction between assembly simplicity and positioning accuracy.
2Device complexity
If the electronic circuit board is directly mounted to the housing, then fewer components are needed, but the risk of tool contact damaging circuit components increases
Solution Approach 1:
The holder serves as a protective intermediary between assembly tools and the electronic circuit board. During the assembly process, tools interact with the holder (inserting through guide holes, tightening screws) rather than directly contacting the circuit board. This intermediary structure reduces the risk of tool contact damaging sensitive circuit components while only adding one relatively simple component to the system.
3Productivity
If screw holes are aligned without guides, then the assembly process is faster, but the positioning accuracy of the electronic circuit board deteriorates
Solution Approach 1:
The holder is pre-equipped with guide holes at predetermined positions that correspond to screw hole locations on the circuit board and housing. Before the actual screw fastening operation, the operator simply needs to insert the screw through the guide hole, which automatically aligns it with the corresponding screw holes. This preliminary preparation of guide holes enables rapid and accurate positioning without requiring time-consuming manual alignment, thus resolving the contradiction between assembly speed and positioning accuracy.
4Object-affected harmful factors
If the holder covers the entire electronic circuit board, then protection is maximized, but the holder size and complexity increase
Solution Approach 1:
The holder is designed to cover only the critical areas of the electronic circuit board that require protection during assembly, rather than covering the entire board. The holder's size and shape are optimized to provide adequate protection for vulnerable components and mounting areas while minimizing overall holder dimensions. This localized protection approach maintains sufficient protection levels while avoiding unnecessary increases in holder size and structural complexity.
Data Source
AI summary
A drive unit for an electrically assisted vehicle includes an electric motor, an electronic circuit board including a control circuit that controls rotation of the electric motor, a holder that covers an entirety or a portion of the electronic circuit board and is fixed to the electronic circuit board, and a housing that accommodates the electric motor, the electronic circuit board, and the holder, such that the electronic circuit board is at a deeper position than the holder. A position of the holder on the electronic circuit board is fixed by tabs. The holder and the electronic circuit board are fixed to the housing by fasteners extending through first holes in the electronic circuit board and second holes in the holder.