Adjustable Leg Latch Assembly With External Lever Release
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Solution Overview
Problem
Existing adjustable leg mechanisms in medical assistance devices, such as walkers and safety seats, require significant strength to operate due to the small area of the detent, making it difficult for users with limited strength, particularly those with rheumatoid arthritis, to adjust the leg length.
Innovation Solution
A latch assembly with an externally located lever that provides a mechanical advantage to rotate the detent between latched and unlatched positions, allowing easier adjustment of the leg length by distributing the force over a larger area, featuring a pivotally supported lever and a spring-biased detent within a pocketed body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a small detent is used to engage adjustment holes, then the leg mechanism can be compact and simple, but significant strength is required to operate it
Solution Approach 1:
A lever is introduced as an intermediary component between the user's hand and the detent. The lever pivots on the first leg and transfers force to the detent, allowing the user to apply force at a more convenient location with better mechanical advantage rather than directly on the small detent surface.
Solution Approach 2:
The lever extends the interaction to a different spatial dimension by providing an external hand-operable surface that is radially spaced from the detent. This allows force application in a more accessible direction and location, converting a difficult direct linear push on a small surface into a more manageable rotational motion of the lever.
2Device complexity
If force is concentrated on a small detent area, then the mechanism remains simple, but users with limited strength cannot operate it
Solution Approach 1:
The lever serves as a force-multiplying intermediary that distributes the required operating force over a larger effective area. Instead of concentrating force on the small detent surface area, the lever provides a larger moment arm and external application surface, reducing the strength requirement for users.
Solution Approach 2:
The system transitions from a static direct-force mechanism to a dynamic lever-based system where force is applied through rotational motion. This dynamic approach allows users to leverage body weight and larger muscle groups rather than relying solely on finger or hand strength concentrated on a small area.
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 latch assembly reduces the required strength for adjusting leg length, making it easier for users to operate, particularly those with limited strength, by allowing axial movement of the leg portions and maintaining alignment through anti-rotation features.
Implementation Method 1
A spring biases the detent to the latched position
Implementation Method 2
An externally located lever is supported relative to the first leg. The lever cooperates with a detent received in one of the adjustment holes in a latched position
Data Source
AI summary
An adjustable leg for a device includes first and second legs telescopically received relative to one another. The second leg has multiple adjustment holes. An externally located lever is supported relative to the first leg. The lever cooperates with a detent received in one of the adjustment holes in a latched position in which the first and second legs are fixed relative to one another. The lever includes an area spaced from the detent that is rotatable about a pivot from the latch position to an unlatched position in which the detent is disposed outside one of the adjustment holes. In the unlatched position, movement of the first and second legs in an axial direction relative to one another is permitted.