Nested Crushable Tube Piston Assembly for Long Stroke Adjustment
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Solution Overview
Problem
Existing brake systems with crushable bodies are limited in longer stroke applications, as increasing the stroke length requires a longer crushable body, thereby increasing the axial envelope of the assembly, which can be impractical for space-constrained systems.
Innovation Solution
A piston assembly with a crushable body comprising an inner and outer thin-walled tube that reduces in axial length when a predetermined force is applied, allowing for a longer stroke without increasing the axial envelope, utilizing a spring and spring guide to limit the piston's return stroke and incorporating an outer crushable tube for additional extension without adding to the axial length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the stroke length is increased by using a longer crushable body, then the piston can accommodate wear over multiple cycles, but the axial envelope of the assembly increases
Solution Approach 1:
The inner crushable tube is nested within the outer crushable tube, with the inner tube positioned concentrically inside the outer tube. This nested configuration allows both tubes to contribute to the stroke length while occupying the same radial space, thereby increasing the effective stroke without proportionally increasing the axial envelope of the assembly.
Solution Approach 2:
The solution transitions from a single-dimensional (axial) arrangement to a multi-dimensional configuration by utilizing both axial and radial dimensions. The outer tube extends radially outward to provide additional crushable material for increased stroke, while the nested inner tube ensures that the radial expansion does not significantly increase the overall axial envelope.
2Length of moving object
If a single crushable tube is used, then the structure is simple, but the stroke length is limited and the axial envelope increases for longer strokes
Solution Approach 1:
The inner crushable tube is nested within the outer crushable tube, creating a compact multi-component structure. The inner tube is positioned inside the outer tube with their ends aligned, allowing both tubes to function together as a unified crushable assembly. This nested arrangement increases stroke capability while minimizing the increase in axial envelope.
Solution Approach 2:
The inner and outer crushable tubes are combined to form an integrated adjuster assembly. Both tubes are configured to crush axially in response to piston movement, and their combined crush distance provides the increased stroke length needed to accommodate wear over multiple brake cycles.
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 enables a longer stroke length within the same axial envelope, maintaining the release clearance and adjusting for wear over multiple cycles, while preventing under-adjustment and allowing for easy maintenance by minimizing the number of parts.
Implementation Method 1
the thin-walled tubes configured to form a crushed body of reduced axial length compared to the axial length of the thin-walled tube when a predetermined force is applied to the thin-walled tube
Implementation Method 2
a spring and spring guide to limit the piston's return stroke
Data Source
AI summary
A piston assembly for engaging two selectively engageable parts comprising: a housing defining a piston cylinder; a piston; and an adjuster assembly comprising: a piston stroke limiter configured to limit the length of a return stroke of the piston from an extended stroke position and a retracted stroke position, the piston stroke limiter comprising a spring and a spring guide; and a crushable body, acting between the piston and the piston stroke limiter, the crushable body being arranged to reduce in axial length when a length of an extension stroke exceeds a length of a retraction stroke to maintain the length of the return stroke; wherein the crushable body comprises an inner crushable thin-walled tube surrounding at least a portion of the piston and an outer crushable thin-walled tube mounted around and radially outwards of the inner crushable tube.