Isoelastic Counterbalance Arm with Toggle Linkage
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Solution Overview
Problem
Existing counterbalance apparatuses for supporting loads are cumbersome to adjust for varying weights, often require multiple adjustments, and may compromise isoelasticity, leading to inconsistent performance and safety issues, particularly in medical and industrial settings where precise control and safety are critical.
Innovation Solution
A counterbalance apparatus featuring a base, load-bearing arm with a parallelogram linkage, toggle linkage, and resilient members that adjust the support vector to counterbalance loads of different weights, allowing for isoelastic movement with minimal user effort and enhanced safety through a single-point adjustment mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple adjustments are made to various elements to adjust the load carrying capacity, then the load carrying capacity can be adjusted, but the adjustment process becomes slow and cumbersome
Solution Approach 1:
The patent combines multiple adjustment functions into a single adjustment mechanism. The single adjustable element simultaneously controls both the spring preload and the counterbalance moment arm length, allowing load carrying capacity adjustment through one unified adjustment action rather than multiple separate adjustments.
Solution Approach 2:
The single adjustable element serves multiple functions: it adjusts the spring preload force and simultaneously modifies the counterbalance moment arm length. This multi-functional design allows one element to perform what previously required multiple separate adjustment mechanisms.
2Adaptability or versatility
If rate adjustment is increased to allow operation at extreme angles, then the range of motion is improved, but isoelasticity decreases degrading overall performance
Solution Approach 1:
The patent dynamically changes the counterbalance moment arm length as a parameter to maintain isoelasticity across the full range of motion. By adjusting this parameter simultaneously with spring preload, the system preserves constant force characteristics even at extreme angles where traditional mechanisms would fail.
Solution Approach 2:
The counterbalance mechanism transitions from a static fixed configuration to a dynamic adjustable configuration. The moment arm length varies dynamically with the arm position and load conditions, allowing the system to maintain optimal performance characteristics across all operating angles rather than being optimized for a single position.
3Force
If high torque motors are used to counterbalance the load weight, then the counterbalance force is sufficient, but the motors may drive the arm into the patient with excessive force in case of malfunction
Solution Approach 1:
The patent uses a passive spring-based counterbalance mechanism that naturally provides the counterbalance force through mechanical means rather than active motor control. The spring force automatically adjusts to counteract the load weight, eliminating the need for high torque motors and their associated safety risks of uncontrolled force application.
Solution Approach 2:
The spring-loaded counterbalance mechanism is self-regulating and does not require external power or control systems. The spring automatically provides the appropriate counterbalance force based on the arm position and load, eliminating the need for motors that could malfunction and apply excessive force.
4Force
If traditional arms use motors to counterbalance weight, then counterbalance function is achieved, but the arm loses its pose and slumps under its own weight in power failure
Solution Approach 1:
The spring-based counterbalance mechanism provides passive mechanical support that does not depend on electrical power. The spring force continuously acts to counterbalance the arm and load weight, maintaining the arm's pose even during power failures, unlike motor-driven systems that require continuous power to maintain position.
Solution Approach 2:
The counterbalance mechanism is entirely passive and self-sufficient, requiring no external power source. The spring automatically maintains the counterbalance force and arm position regardless of power availability, providing inherent stability without needing brakes or locking mechanisms.
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 apparatus effectively counterbalances loads with varying weights, providing consistent isoelastic movement and improved safety by negating gravity, reducing user effort, and ensuring stability even in power failures, thus addressing the limitations of prior art devices.
Implementation Method 1
a first resilient member adapted to apply a force to the load bearing arm... and a second resilient member adapted to apply a force to the load bearing arm
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A counterbalance apparatus for supporting a load is provided. The apparatus includes a base, a load bearing arm, a toggle linkage, and first and second resilient members for applying a force to the load bearing arm. The load bearing arm consists of a plurality of pivot points forming a parallelogram linkage, may project from the base at an attachment point and is adapted to support the load at a distal end. The toggle linkage may be pivotally connected to the base and moveable between a non-load bearing position and a load bearing position. The toggle linkage may also comprise an adjustment member positioned to define a distance relative to the attachment point. The first resilient member is adapted to apply a force to the load bearing arm and may have a first end connected to a first portion of the parallelogram linkage and a second end connected to the adjustment member; and the second resilient member is also adapted to apply a force to the load bearing arm and may have a first end connected to a second portion of the parallelogram linkage and a second end connected to the adjustment member. Movement of the toggle linkage from the non-load bearing position to the load bearing position engages the forces of the resilient members and movement of the adjustment member varies the distance to adjust a support vector adapted to counterbalance the load vector.