Stay Drop-off Structure with Segmented Slits for Impact Load Response
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Solution Overview
Problem
Existing stay drop-off structures, such as those described in Japanese Patent No. 3954477, are prone to unintended separation of the stay from the mount bracket due to the equal dimensions of the slit width and the stud bolt's outer diameter, leading to potential displacement during events other than impact loads, such as loosening of the threaded portion.
Innovation Solution
A stay drop-off structure featuring a recessed portion with a cutout portion that is dimensioned to allow the bolt head to pass through only under impact load, preventing unintended separation by ensuring the bolt remains fastened in normal conditions and allowing controlled separation during impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the dimension of the slit in width direction is set equal to the outer diameter of the threaded portion of the stud bolt, then the stay can be separated from the mount bracket upon impact load, but the stud bolt may be displaced through the slit from the bolt hole in events other than impact load such as loosening of the threaded portion
Solution Approach 1:
The invention divides the single slit structure into multiple slits (first slit and second slit) positioned at different locations. The first slit has a width equal to the stud bolt outer diameter, while the second slit has a smaller width. This segmentation allows the stud bolt to pass through the first slit during impact load while being retained by the second slit during normal operation, thus resolving the contradiction between impact response reliability and prevention of unintended drop.
Solution Approach 2:
The invention applies different width dimensions to different slits based on their specific functions. The first slit is designed with a width equal to the stud bolt outer diameter to facilitate impact load separation, while the second slit is designed with a smaller width to prevent unintended displacement. This local differentiation of geometric properties allows each slit to perform its specific function optimally.
2Ease of operation
If the dimension of the slit in width direction is set equal to the outer diametrical dimension of the threaded portion of the stud bolt, then the stay can drop upon impact load, but the stay may drop in events other than impact load due to displacement of the stud bolt through the slit
Solution Approach 1:
The invention segments the ejection path into two distinct slits with different width characteristics. The first slit provides a wide passage for impact load ejection, while the second slit provides a narrow retention barrier. This segmentation enables the system to achieve both easy separation during impact and reliable retention during normal operation.
Solution Approach 2:
Instead of using a single slit that allows passage in all conditions, the invention inverts the approach by using a combination of slits where one allows passage (first slit) and the other prevents passage (second slit) under normal conditions, reversing the typical single-opening design logic.
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
The structure reliably causes the stay to drop upon impact while preventing unintended drops due to factors like loosening of the bolts, ensuring the stay remains secured in non-impact scenarios.
Implementation Method 1
the head portion of the first bolt is capable of passing through the cutout portion deformed by the input of an impact load
Data Source
AI summary
A stay includes a first-bolt hole portion fastened to a body frame by a first bolt, a second-bolt hole portion fastened to a subframe by a second bolt, a recessed portion disposed between the first-bolt hole portion and the second-bolt hole portion and recessed downward, and a cutout portion continuous with the first-bolt hole portion and formed by cutting out a part of the recessed portion. The dimension of the recessed portion in its depth direction is equal to or larger than the dimension of the head portion of the first bolt in its height direction. The widthwise dimension of the cutout portion in a direction perpendicular to an axis of the stay is set to be smaller than the largest outer diameter of the head portion of the first bolt.