Load Cell Support Structure with Pivot and Biasing for Eccentric Load Protection
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Solution Overview
Problem
Current load cell support structures in weighing scales inadequately protect against low-frequency vibrations and eccentric loads, as they rely on stiff force sensors that deflect minimally under load, making it difficult to accurately adjust protection gaps and leading to unpredictable stability and inaccurate load limitation, especially for off-center loads.
Innovation Solution
A load cell support structure featuring a base support member, a load bearing member with a load cell engaging member, a load transfer member, and biasing members that apply a predetermined force opposing the load, along with pivot members allowing pivotal movement, enabling accurate and predictable load release conditions and improved stability by allowing preloading springs to be positioned variably and limiting forces beyond the pivot limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If deflection limiting gaps are used to protect the load cell from overload, then the load cell is protected from centred overload conditions, but the structure becomes difficult to adjust with sufficient accuracy and does not sufficiently prevent low frequency vibration
Solution Approach 1:
The patent changes the fundamental parameter of load cell support from rigid gaps to compliant preloaded springs. This allows the system to maintain protection functionality while enabling easy adjustment of the preload force parameter to control when load release occurs, eliminating the difficulty of precise gap adjustment.
Solution Approach 2:
The patent transitions from static rigid gaps to dynamic preloaded springs that can adapt to different load conditions. The springs provide continuous compliance and can be adjusted to different preload levels, enabling the system to respond dynamically to varying load magnitudes and frequencies.
2Reliability
If preloading springs are used to support the load and absorb impact energy, then larger dimensioned gaps can be used at the corners, but the arrangement provides unpredictable stability and inaccurate limitation range for off-centre loads
Solution Approach 1:
The patent replaces the complex mechanical arrangement of multiple preloaded springs with a simpler pivot mechanism. The pivot provides a defined fulcrum point that creates predictable load paths and moment arms, eliminating the unpredictable stability issues associated with multiple spring arrangements while maintaining impact energy absorption capabilities.
Solution Approach 2:
The pivot mechanism creates a counterbalancing effect where the load cell reacts to loads through a defined pivot point. This provides accurate limitation of off-centre loads by creating predictable moment arms and load paths, allowing precise control of the limitation range.
3Device complexity
If stiff force sensors are used, then the scale structure is simplified, but the sensors deflect very little under load making it difficult to accurately adjust protection gaps
Solution Approach 1:
The patent introduces preloaded springs as an intermediary element between the stiff load cell and the load bearing structure. This mediator provides the necessary compliance and visible deflection for accurate adjustment, while the stiff load cell maintains its structural advantages. The spring acts as a buffer that translates small load cell deflections into measurable movements.
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
This configuration provides highly accurate and stable operation up to maximum overload release forces, allowing greater design flexibility and effective limitation of forces transferred to the load cell, while reducing the risk of damage from eccentric and off-center loads.
Implementation Method 1
at least one biasing member adapted to urge said load transfer member towards said load cell engaging member with a predetermined biasing force
Implementation Method 2
at least one pivot members operatively engaging said load transfer member and said load cell engaging member, so as to allow pivotal movement of said load transfer member with respect to said load cell engaging member about said pivot members
Data Source
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AI summary
A load cell support structure for a scale comprising a base support member for mounting at least one load cell; a load bearing member movable with respect to said base support member and having an upper surface for receiving a load; a load cell engaging member adapted to operatively engage at least one load cell in a direction of a load applied to said upper surface of said load bearing member; a load transfer portion integrally formed with said load bearing member and operatively coupled to said load cell engaging member so as to transfer a load from said upper surface to at least one load cell via said load cell engaging member; at least one biasing member adapted to urge said load transfer member towards said load cell engaging member with a predetermined biasing force and in a direction opposing a load applied to said upper surface of said load bearing member; at least one pivot member operatively engaging said load transfer member and said load cell engaging member, so as to allow pivotal movement of said load transfer member with respect to said load cell engaging member about said pivot member and in at least one plane parallel to the direction of a load applied to said upper surface.