Rack Arm Counterbalance Spring With Nonlinear Cam Force Transfer
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Solution Overview
Problem
Movable rack arms in surgical equipment often lack precise control, leading to unintended movement during surgeries, which can disrupt procedures and potentially harm patients due to inadequate counterbalance mechanisms.
Innovation Solution
A movable rack arm assembly with a counterbalance spring system that includes a cam housing, circular gear, rack arm, and spring assembly, allowing for contoured non-linear force transfer, enabling precise control and minimizing accidental movement by varying the force required for extension and retraction based on the arm's position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a counterbalance spring is used to prevent the rack arm from moving too easily, then stability is improved, but the rack arm becomes difficult to move when intentional adjustment is needed
Solution Approach 1:
The cam mechanism transforms the static counterbalance spring force into a dynamic, position-dependent force. As the rack arm moves through different positions, the cam profile varies the effective leverage of the spring, creating regions of high stability (when surgical equipment should remain stationary) and regions of ease of movement (when intentional adjustment is needed). This resolves the contradiction by making the counterbalance force adaptive rather than constant.
Solution Approach 2:
The invention changes the parameter of counterbalance force from a constant value to a variable value that depends on the rack arm position. The cam profile is specifically designed to modulate the spring force, increasing it at positions where stability is critical and decreasing it where manual adjustment should be facilitated. This parameter change allows the system to simultaneously achieve both stability and ease of operation at different operational phases.
2Device complexity
If a linear counterbalance spring is used, then the mechanism is simple, but it cannot provide precise control at different positions of the rack arm
Solution Approach 1:
The cam mechanism introduces a curved geometric element that transforms the linear motion of the rack arm into a controlled rotational motion with variable leverage. The specific curvature of the cam profile is designed to produce the desired non-linear force characteristics, providing precise position control without requiring a complex multi-component mechanism. This curved geometry elegantly solves the precision control problem while maintaining relative simplicity.
3Device complexity
If the counterbalance force is constant, then the spring mechanism is simple, but it allows accidental movement during surgery
Solution Approach 1:
The invention changes the counterbalance force parameter from constant to variable based on rack arm position. The cam profile is designed to create high counterbalance forces at surgical operating positions, preventing accidental movement during procedures. The mechanism remains relatively simple as it uses the existing spring force, merely modulating its effectiveness through the cam's geometric transformation rather than requiring an actively controlled system.
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 system provides controlled and stable movement of surgical equipment, reducing the risk of accidental displacement during surgeries by applying a non-linear force profile, thus enhancing surgical precision and safety.
Implementation Method 1
The spring assembly includes a spring, a spring arm attached to the spring at a first end
Implementation Method 2
The cam includes a curved cam groove having an inner end and an outer end, wherein the inner end is located radially closer to the axle than the outer end
Implementation Method 3
a circular gear including circular gear teeth and mounted on and rotatable about the axle
Data Source
AI summary
The present disclosure relates to a movable rack arm assembly including a cam housing, a circular gear, a rack arm, a cam, and a spring assembly for contoured non-linear force transfer.