Motor Casing Lid Fixation via Biting Bend Portions
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Solution Overview
Problem
Existing methods for fixing a resin casing lid to a metal motor casing are prone to loosening due to dimensional changes caused by temperature and humidity, and they either require costly adhesives or risk deformation and breakage when attempting to secure the lid firmly.
Innovation Solution
The motor casing is designed with bend portions that bite into fixation portions on the casing lid, featuring noncontact regions such as grooves, allowing the resin to escape and concentrating the biting force, thus preventing loosening and deformation without the need for adhesives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bend portions of the motor casing are increased in length and bent deeper to prevent loosening, then the fixation firmness is improved, but deformation or breakage of the casing lid may result
Solution Approach 1:
The invention introduces noncontact regions at the tips of bend portions where the metal casing does not contact the resin lid, allowing resin to escape and concentrate biting force at specific locations. This creates localized high-stress biting zones rather than distributed contact, preventing both loosening and lid deformation by optimizing the stress distribution pattern.
Solution Approach 2:
The bend portions are designed with segmented contact patterns through the noncontact regions, dividing the continuous bending force into discrete biting points. This segmentation allows the fixation structure to achieve firm holding while distributing mechanical stress to prevent catastrophic failure of the resin lid.
2Reliability
If adhesive is used to fix the casing lid and bent pawls together, then the fixation firmness is improved, but separation may occur under temperature and humidity influence and cost increases
Solution Approach 1:
The invention extracts and eliminates the adhesive from the fixation system, replacing it with a purely mechanical biting structure. The noncontact regions enable the metal bend portions to bite directly into the resin lid without adhesive, simplifying the fixation structure while maintaining reliability through the concentrated biting force mechanism.
Solution Approach 2:
The bend portions are designed to automatically bite into the resin lid through their own elastic deformation, without requiring adhesive or additional fastening components. The elastic recovery force of the bent metal portions provides self-contained fixation, making the system self-sufficient and eliminating dependency on adhesive bonding.
3Reliability
If the opening end portion of the motor casing is bent at several positions to fix the casing lid, then the fixation firmness is improved, but clearance is generated at fixed portions when dimensional change occurs toward the center of the casing lid
Solution Approach 1:
The invention changes the geometric parameters of the bend portions by introducing noncontact regions at their tips. This parameter modification transforms the contact pattern from continuous to discontinuous, enabling the structure to accommodate dimensional changes of the resin lid while maintaining fixation accuracy through concentrated biting at specific points rather than distributed contact.
Data Source
AI summary
The present invention enables firm fixation between a motor casing and a casing lid at low cost through employment of a simple structure without need to use adhesive. A casing lid made of resin is fixedly fitted to an opening portion of a motor casing made of metal. Grooves or depressions are provided at the bottoms of a plurality of fixation portions provided on the casing lid at constant intervals in the circumference direction thereof. Bend portions at the opening portion of the motor casing are caused to bite into the grooves or depressions of the casing lid fitted into the opening portion of the motor casing, whereby the motor casing and the casing lid are fixed together.