Spring Balancing Mechanism for Rotating X-ray Arm Torque
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Solution Overview
Problem
Current X-ray imaging systems with a rotational arm, such as mammography systems, are unbalanced due to the center of mass being offset from the axis of rotation, requiring significant torque to rotate, which increases the power requirement of the actuation system and leads to system fatigue and high costs due to counterbalance mechanisms like counterweights or gas springs.
Innovation Solution
A balancing system using a spring mechanism with a geometric constraining point and an active connection point, where the spring force balances the gravitational torque of the arm, reducing the torque required for rotation and eliminating the need for heavy counterweights by optimizing the spring rate and connection point distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If counterweights are used to balance the arm, then the torsional force required for rotation is significantly reduced, but the weight and cost of the system increase significantly
Solution Approach 1:
The patent uses a spring mechanism to provide a counteracting force that balances the gravitational torque of the arm. The spring is positioned and configured to generate a force that opposes the weight of the arm during rotation, effectively reducing the net torque required without adding significant weight through traditional counterweights.
Solution Approach 2:
The patent replaces the traditional mechanical counterweight system with a spring-based mechanism. This substitution eliminates the need for heavy counterbalancing masses while achieving the same torque-balancing effect through elastic mechanical energy storage and release in the spring.
2Force
If counterweights are used to balance the arm, then the torsional force required for rotation is reduced, but the system becomes difficult to move from place to place
Solution Approach 1:
The spring mechanism provides the necessary counterbalancing force without requiring heavy counterweights, thereby maintaining the ease of moving the entire mammography system to different locations while still reducing the operational torque during arm rotation.
Solution Approach 2:
By replacing the heavy counterweight mechanism with a compact spring-based system, the overall weight and complexity of the moving components are reduced, making the system more portable and easier to reposition without sacrificing rotational balance.
3Force
If a gas spring is used to counterbalance the arm, then the arm is balanced through a gear set, but the gas spring force degrades up to 20% over its lifespan and has very limited cycle life
Solution Approach 1:
The patent specifies a spring rate of approximately 400 N/m and positions the spring to act at a distance of about 0.5 meters from the pivot point. These parameter optimizations ensure the spring maintains consistent force characteristics throughout its operational lifespan, avoiding the degradation issues associated with gas springs.
Solution Approach 2:
The patent employs a mechanically simple spring mechanism that, while having a finite lifespan, avoids the complex sealing and pressure maintenance issues of gas springs. The solid-state spring mechanism is more reliable for high-cycle applications and can be more easily replaced or maintained.
4Force
If current counterbalance mechanisms are used, then some torque reduction is achieved, but 90% of the motor power is still used to compensate for the unbalanced gravitational load
Solution Approach 1:
The spring mechanism is specifically configured to counterbalance the gravitational torque of the arm, creating a near-perfect balance that eliminates the need for the motor to compensate for gravitational effects. This reduces motor power consumption from 90% to approximately 10% of the original requirement.
Solution Approach 2:
By replacing the inadequate partial-balancing mechanisms with a properly designed spring system, the patent achieves complete gravitational torque compensation, thereby dramatically reducing the energy burden on the motor and improving overall system efficiency.
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 proposed balancing system significantly reduces the power requirement of the actuation system by approximately 80%, extends the life expectancy of the system, and minimizes weight, making it more cost-effective and efficient by completely counterbalancing the gravitational torque at any angle.
Implementation Method 1
The counterbalance mechanism includes a spring mechanism configured to apply a counteractive force to the arm. The spring mechanism includes a spring having a spring rate of approximately 400 N/m.
Implementation Method 2
the center of mass of the rotatable C-arm is typically spaced apart from the axis of rotation, and is therefore 'unbalanced' about the axis of lateral rotation. In an unbalanced system, a significant torque must be applied to rotate the arm to a desired position.
Data Source
AI summary
An apparatus for balancing a statically unbalanced system, particularly useful in balancing X-ray and mammography systems having an X-ray source and detector mounted to a rotational arm, includes a spring mechanism which synchronizes the activation of the spring mechanism with the rotation of the arm of the mammography system. The balancing system reduces the amount of torque necessary to rotate the arm and decreases the overall inertia of the system by eliminating the need for counterweights to maintain balance of the system.