Rod Load Cell With Segmented Strain Member
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Solution Overview
Problem
Traditional strain gage load cells face inaccuracies when measuring load on a rod due to unpredictable contact points between the rod and the strain gage, leading to inconsistent deformation and measurement errors.
Innovation Solution
A cylindrical strain member with slots forming predictable contact points is used, accompanied by strain gages adjacent to these points to produce an electrical voltage proportional to the load on the rod, ensuring consistent and accurate measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional strain gage load cells are used to measure load on a rod, then the measurement can be obtained, but the contact points between the rod and strain gage are unpredictable leading to measurement errors
Solution Approach 1:
The strain member is segmented by forming slots through its circumference, which divides the continuous surface into discrete sections. This segmentation creates defined contact regions between the rod and strain member, ensuring predictable and consistent contact points. The slots effectively break up the surface to control where contact occurs, resolving the reliability issue of unpredictable contact points while maintaining measurement precision.
Solution Approach 2:
The invention applies local quality by creating specific zones on the strain member - the slot areas represent non-contact zones while the areas between slots represent contact zones. This local differentiation ensures that contact occurs only at predetermined locations, making the contact points predictable and consistent. The strain gages are strategically positioned adjacent to these contact points to accurately measure the localized deformation.
2Measurement precision
If strain gages are positioned without controlled contact points, then the device structure is simpler, but the deformation measurement becomes inconsistent
Solution Approach 1:
The strain member incorporates slots that segment its structure, creating a pattern of contact and non-contact zones. This segmentation is achieved by forming slots through the circumference of the strain member, which adds structural complexity but ensures consistent deformation patterns. The segmentation allows the strain gages to reliably measure deformation at predictable locations, improving measurement consistency despite the increased structural complexity.
Solution Approach 2:
The slots are pre-formed in the strain member during manufacturing, establishing the contact points before the load cell is installed and used. This preliminary action of creating the slot pattern ensures that when the rod is inserted, contact occurs at the predetermined locations between the slots. The strain gages are also pre-positioned adjacent to these contact points, ensuring consistent measurement geometry from the first use.
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 more accurate and consistent load measurements by controlling the contact points between the rod and the load cell, enhancing the precision of strain gage readings in applications like oil and gas well rod pumping.
Implementation Method 1
The strain gage measures deformation as an electrical signal because the strain changes the effective electrical resistance of the wire
Implementation Method 2
the force deforms a strain gage
Data Source
AI summary
A load cell for measuring load in a rod, the load cell is described. The load cell is formed by a cylindrical strain member having a cylindrical aperture there through. The cylindrical aperture sized to fit the rod. The strain member includes a plurality of slots that create contact points there between for strain member to contact the rod in a predicable manner. A plurality of strain gages located adjacent to the contact points, the strain gages producing an electrical voltage proportional to the load on the rod.