Nested Bellows Boot Structure for Shorter Compression Stroke
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Solution Overview
Problem
Existing boots for forward/backward movement members, such as those used in fuel lid opening/closing devices, are too long when compressed and exhibit excessive restoring forces, leading to design issues and potential lifting off from the vehicle body.
Innovation Solution
A tubular boot design with a bellows portion and an extending portion, where the extending portion's outer diameter is smaller than the bellows portion's inner diameter, allowing it to be displaced into the bellows portion when compressed, thereby reducing the boot's length and restoring force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the boot is made longer to protect the tappet shank when the flap is opened, then the protection capability is improved, but the boot length when compressed becomes excessive and cannot fit in narrow spaces
Solution Approach 1:
The extending portion is designed with an outer diameter smaller than the inner diameter of the bellows portion-side valley portion, allowing it to be nested inside the bellows portion when the boot is compressed. This nesting configuration enables the boot to achieve a compact compressed length while maintaining sufficient extended length for protection when the flap is opened.
2Reliability
If the boot is made longer to ensure adequate coverage, then the sealing effectiveness is improved, but the restoring force when compressed increases excessively causing the flap to lift off
Solution Approach 1:
By enabling the extending portion to nest inside the bellows portion during compression, the overall compressed length is reduced. This reduction in compressed length directly decreases the restoring force generated by the boot, preventing excessive flap lifting while maintaining adequate boot length for effective sealing when extended.
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 design achieves a shorter boot length with reduced restoring force, accommodating it in narrow spaces and preventing lifting off from the vehicle body, while maintaining effective protection against water and dust.
Implementation Method 1
the extending portion is configured so that at least a part of the extending portion is displaced into the bellows portion when the boot is compressed in the axis direction
Data Source
AI summary
A boot of extends along an axis X direction and has a cylindrical shape that is extendable and contractable in the axis X direction. The boot includes a bellows portion alternately having a bellows portion-side peak portion and a bellows portion-side valley portion along the axis X direction, and an extending portion connected adjacent to the bellows portion in the axis X direction and provided adjacent to one end and/or an other end of the boot in the axis X direction. The extending portion is formed so that an outer diameter of an end of the extending portion on a side opposite to a side connected to the bellows portion in the axis X direction is smaller than an inner diameter of the bellows portion-side valley portion of the bellows portion.