Dual-Truncated Wheel Kibble Balance With Flexure Pivot Precision
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional Kibble balances face challenges with measurement errors due to hysteresis and limited deflection in their knife edge pivots, which affect the precision and accuracy of mass determination.
Innovation Solution
The dual-truncated wheel Kibble balance employs a flexure pivot mechanism with a central flexural bridge and connector bands to constrain motion to one degree of freedom, allowing for high-precision, linear motion and reduced hysteresis, enabling accurate mass determination in both weighing and moving modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a knife edge pivot is used in conventional Kibble balances, then the balance can achieve mass determination capability, but measurement precision deteriorates due to hysteresis and limited deflection
Solution Approach 1:
The patent replaces the traditional knife edge mechanical pivot with a flexure pivot mechanism. The flexure pivot uses elastic deformation of a flexural bridge to achieve rotational motion without mechanical contact, thereby eliminating hysteresis and friction associated with knife edge pivots. This substitution of mechanical contact-based rotation with elastic deformation-based rotation directly resolves the hysteresis error problem while maintaining the balance functionality.
Solution Approach 2:
The patent changes the physical parameters of the pivot system by using a flexure with specific elastic properties. The flexural bridge is designed with controlled dimensions and material properties to provide the required deflection range while minimizing hysteresis. By adjusting the flexure geometry and material parameters, the system achieves both adequate deflection for mass determination and reduced hysteresis for improved measurement precision.
2Measurement precision
If a flexure pivot mechanism is used to reduce hysteresis, then measurement precision improves, but device complexity increases due to the dual-truncated wheel and connector band structure
Solution Approach 1:
The patent merges multiple functions into the dual-truncated wheel structure. The wheel serves as both the balancing element and the motion constraint mechanism. The connector bands integrate the function of suspending the wheel while simultaneously constraining its motion to one degree of freedom. This merging of functions reduces the number of separate components needed, thereby managing device complexity while achieving high measurement precision.
Solution Approach 2:
The flexure pivot mechanism is designed to perform multiple functions: it provides the pivot point for rotation, constrains motion to one degree of freedom through the dual-truncated wheel geometry, and suspends the balancing mass. The connector bands similarly serve both suspension and motion constraint functions. This multi-functionality reduces the overall system complexity by eliminating the need for separate components for each function.
3Measurement precision
If motion is constrained to one degree of freedom using connector bands, then measurement accuracy improves by reducing mechanical nonlinearities, but ease of operation decreases due to restricted movement
Solution Approach 1:
The patent applies local quality by providing different degrees of freedom in different directions. The connector bands constrain motion in horizontal directions to eliminate parasitic movements that would reduce measurement accuracy, while allowing free motion in the vertical direction where the balancing action occurs. This selective constraint approach improves measurement accuracy without unduly restricting the operational motion needed for mass determination.
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 dual-truncated wheel Kibble balance achieves sub-micron level precision and suspends up to 15 kg with minimal hysteresis, providing a compact, high-precision mechanism for determining absolute mass with reduced mechanical nonlinearities.
Implementation Method 1
the central flexural bridge is: interposed between the stationary frame and the double balance wheel, interconnects the stationary frame and the double balance wheel, and flexes in response to pivotal motion of the double balance wheel relative to the stationary frame
Implementation Method 2
a first outer connector band disposed on the first outer wheel head at the outer peripheral radial surface, such that the first outer connector band is gravitationally suspended from the first outer wheel head
Data Source
AI summary
A dual-truncated wheel Kibble balance includes: a stationary frame; a double balance wheel disposed on the stationary frame; a pair of guide members, such that one of the guide members is disposed on each opposing end of the double balance wheel; outer connector bands, such that each guide member is gravitationally suspended from the double balance wheel by at least one of the outer connector bands; inner connector bands, such that each guide member is gravitationally suspended from the double balance wheel by at least one of the inner connector bands; and a central flexural bridge in mechanical communication with the stationary frame and the double balance wheel, such that the central flexural bridge is: interposed between the stationary frame and double balance wheel, interconnects the stationary frame and the double balance wheel, and flexes in response to pivotal motion of the double balance wheel relative to the stationary frame.