Motor Unit Cover Structure for Clean Bus Bar Terminal Fitting
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Solution Overview
Problem
Existing motor designs face issues with dirt and foreign substances entering the fitting location of bus bars and contact terminals, leading to potential short-circuiting and increased electrical and thermal resistance.
Innovation Solution
A cover member is interposed between the motor and control substrate, featuring a through hole and enclosing parts to prevent the entry of dirt and foreign substances, with an inclined surface to guide the bus bar terminal correctly and reduce entanglement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the fitting location for the bus bar and contact terminal is exposed, then assembly and maintenance are easier, but dirt and foreign substances can enter causing short-circuiting
Solution Approach 1:
The cover member is inserted into a recess formed in the motor housing, creating a nested structure where the cover is housed within the motor assembly. This nesting approach provides protection against dirt and foreign substances entering the fitting location while maintaining a compact integrated design that does not complicate assembly or maintenance procedures
2Object-affected harmful factors
If a cover member is added to enclose the fitting location, then protection against dirt and short-circuiting is improved, but device complexity increases
Solution Approach 1:
The cover member serves multiple functions simultaneously: it encloses the fitting location to prevent dirt and foreign substances from entering, provides structural support for the bus bar terminal insertion, and acts as a protective barrier against short-circuiting. This multi-functionality reduces the need for additional separate protective components, thereby limiting the increase in device complexity while achieving comprehensive protection
3Manufacturing precision
If the through hole has a tapered inner surface for guiding, then alignment and insertion accuracy are improved, but manufacturing complexity increases
Solution Approach 1:
The through hole is formed with a tapered (curved) inner surface that gradually narrows in the insertion direction. This curvature provides a guiding function that automatically aligns the bus bar terminal during insertion, improving alignment accuracy and preventing misalignment. The tapered geometry can be manufactured using standard machining or molding techniques, balancing the need for precision with manufacturing simplicity
4Strength
If the cover member is made of metal for strength, then mechanical strength is improved, but thermal influence between motor and control substrate increases
Solution Approach 1:
The cover member is made of resin (polymer material) instead of metal. Resin provides sufficient mechanical strength for the application while having low thermal conductivity, which reduces thermal influence between the motor and control substrate. This material selection resolves the contradiction by providing adequate structural support without the thermal conduction problems associated with metal materials
Data Source
AI summary
A cover member for a motor unit is disclosed. The cover member is interposed between a motor and a control substrate for controlling operation of the motor. The motor has a bus bar terminal electrically connected to a coil of a stator of the motor. The control substrate has a connection terminal that is fitted to the bus bar terminal and is made to electrically connect the control substrate to the stator. The cover member has a through hole, through which the bus bar terminal pierces, and an enclosing part for enclosing a fitting location for the bus bar terminal and the connection terminal, as seen in a piercing direction of the bus bar terminal.