Spring-Pulley Arm Support for Rapid Restoring Moment Reduction
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Solution Overview
Problem
Existing arm support mechanisms do not provide a rapid enough reduction in restoring moment as the user lowers their arm, leading to discomfort and interference with free movement.
Innovation Solution
Incorporation of compensation elements such as springs, elongate tension elements, and pulleys that modify the offset force applied by the arm support as it pivots, with features that adjust the attachment point of the tension element to reduce the offset force when the arm is lowered.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If simple trigonometric relationships are used to reduce the moment applied to the arm when the user lowers it, then the arm support mechanism is simple and easy to manufacture, but the reduction in moment is insufficient and does not diminish rapidly enough
Solution Approach 1:
The patent changes the parameter of moment reduction from a simple trigonometric relationship to an exponential decay relationship. By using a spring element with exponential force-displacement characteristics, the restoring moment decreases rapidly as the arm lowers, providing both manufacturing simplicity and high productivity in terms of moment reduction rate.
Solution Approach 2:
The patent employs a spring element as a counterweight mechanism that provides an exponential restoring force. This spring-based counterweight system naturally provides rapid moment reduction through its exponential force-displacement relationship, solving the contradiction between simplicity and rate of reduction.
2Force
If the restoring moment is maximized when the user's arm is horizontal, then the arm support provides maximum support where needed, but the support interferes with free movement when the arm is lowered
Solution Approach 1:
The patent changes the parameter of restoring moment from a constant or linear relationship to an exponential decay relationship. This allows the restoring moment to be maximized when the arm is horizontal (where exponential function has highest value) while rapidly diminishing as the arm lowers, enabling free movement without interference.
Solution Approach 2:
The patent introduces dynamic characteristics through the exponential spring element, allowing the restoring moment to automatically adjust based on arm position. The system dynamically provides maximum support at horizontal positions while naturally reducing support as the arm lowers, enabling ease of operation without mechanical intervention.
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 solution provides a more rapid reduction in restoring moment as the arm is lowered, enhancing user comfort and allowing for extended periods of free arm movement.
Implementation Method 1
one or more compensation elements coupled to the arm support to apply an offset force to at least partially offset a gravitational force acting on the arm as the user raises and lowers the arm. The one or more compensation elements may include a spring including a first end mounted to the arm support
Implementation Method 2
One or more pulleys are mounted on the arm support such that the tension element wraps at least partially around the one or more pulleys to modify the offset force as the user raises and lowers the arm
Implementation Method 3
an elongate tension element, e.g., cable, comprising a first end coupled to a connection post on the connection bracket and a second end coupled to a second end of the spring, thereby defining an axis extending along a segment of the tension element from the second end of the arm support towards the first end of the arm support
Data Source
AI summary
An arm support system includes an arm support coupled to a connection bracket about a pivot joint and carrying an arm rest for receiving a user's upper arm. Compensation elements are coupled to the arm support to apply an offset force to at least partially offset a gravitational force acting on the arm as the user raises and lowers the arm including a spring, a cable coupled between a connection post on the connection bracket and the spring, thereby defining an axis along a segment of the cable, one or more pulleys mounted on the arm support such that the cable wraps at least partially around the pulleys to modify the offset force as the user raises and lowers the arm, and a feature mounted adjacent the connection post that modifies the cable axis relative to the pivot joint to reduce the offset force as the arm support is lowered.