Variable Rigidity Lock Arm for Electric Connection Box
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Solution Overview
Problem
The existing lock mechanisms for electric connection boxes in vehicles face a trade-off between operability for locking and unlocking and lock retention, as increasing flexural rigidity enhances lock retention but requires more force, while reducing it weakens retention but makes operations easier, leading to a balance that is not optimal for both aspects.
Innovation Solution
A lock mechanism with a cantilever lock arm having distinct flexural rigidities in its base, middle, and upper regions, where the middle region has lower rigidity than the base and upper regions, allowing for easier initial displacement and enhanced final lock retention, achieved by varying the rib configuration and shape to adjust flexural properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the flexural rigidity of the lock arm is increased to enhance lock retention, then the lock retention is improved, but the force required for locking and unlocking operations increases
Solution Approach 1:
The lock arm is designed with non-uniform flexural rigidity along its longitudinal direction. The middle region has lower flexural rigidity compared to the base end region and upper end region. This local variation allows the lock arm to have high overall rigidity for secure locking while the softer middle region reduces the force needed for manipulation during locking and unlocking operations.
2Ease of operation
If the flexural rigidity of the lock arm is reduced to make locking and unlocking operations easier, then the operability is improved, but the lock retention is weakened
Solution Approach 1:
The lock arm incorporates a middle region with reduced flexural rigidity that acts as a flexible zone during operations. This local softening allows easier manipulation without compromising the overall lock retention, as the base end region and upper end region maintain sufficient rigidity to ensure secure locking.
3Device complexity
If the entire lock arm is made with uniform flexural rigidity, then the structure is simple, but both operability and lock retention cannot be optimized simultaneously
Solution Approach 1:
The lock arm is designed with spatially varying flexural rigidity, creating distinct regions with different mechanical properties. The middle region has lower rigidity than the base end and upper end regions. This non-uniform structure, while slightly more complex than uniform design, enables simultaneous optimization of both ease of operation and lock retention.
Solution Approach 2:
The lock arm is segmented into functionally distinct regions: a base end region with high rigidity for secure anchoring, a middle region with lower rigidity for flexible manipulation, and an upper end region with high rigidity for effective locking. This segmentation allows each region to be optimized for its specific function.
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
This configuration allows for easier insertion and locking with reduced operational force while maintaining strong lock retention, improving both operability and retention without risking damage to the lock arm.
Implementation Method 1
the lock arm 151 which is provided on the inner wall 118 of the box body 110 so as to protrude obliquely upward from the inner wall 118 in a cantilever manner... the lock arm 151 is temporarily bent due to the interference between the lock arm 151 and a portion of the part 120. Then, after the interference portion on the part 120 passes the lock projection 155, the lock arm 151 returns to the original state
Implementation Method 2
ribs 156 are provided on the lower surface in the base part attached to the inner wall 118. All the regions of the lock arm 151 except for the region having the ribs 156 formed therein are formed to have the cross section of a squared U shape with ribs 152 provided on the both edges of the plate-shaped lock arm 151. By employing such a configuration, the flexural rigidity of the entire lock arm 151 is set approximately uniform.
Data Source
AI summary
A lock mechanism includes: a lock arm provided in a cantilever manner on an inner wall of a part compartment of a box body of an electric connection box; and a lock projection provided to the lock arm on its surface facing a part housed in the part compartment. The lock arm can be divided in a longitudinal direction into: a base end region fixed to the inner wall; upper end region located in the free end which interferes with the part and receives a pressing force for unlocking operation; and a middle region located within a predetermined distance range between the base and upper end region. The flexural rigidity of the base and upper end region is set larger than that of the middle region by providing ribs on the base and upper end region and providing no ribs on the middle region.