Top-pan Balance Corner Load Sensor Overload Protection
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Solution Overview
Problem
Existing scale designs with overload protection mechanisms are bulky, complex, and require additional space, while corner load sensors often fail to provide adequate signals due to dimensional constraints and interference with parallel guidance.
Innovation Solution
Integrating a corner load sensor with the overload protection device as a common assembly behind the overload protection, using thin material areas with strain gauges that are not influenced by parallel guide stability, allowing for thinner sensor components and improved signal output without altering the scale's dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a corner load sensor is dimensioned for maximum overload, then the scale can withstand overload without damage, but the strain gauges cannot provide adequate corner load signals
Solution Approach 1:
The patent divides the load transmission path into two separate functional paths: one for normal weighing (through the parallel guide) and one for overload protection (through the corner load sensor and overload protection device). This segmentation allows the corner load sensor to be optimized for signal quality in the normal range while the overload protection handles extreme loads, resolving the contradiction between strength and measurement precision.
Solution Approach 2:
The patent introduces an intermediary structure (the auxiliary parallel guide with prestressed spring element) between the weighing pan support and the load receiver. This intermediary allows the corner load sensor to operate within its optimal signal range while still providing overload protection, as the intermediary absorbs or limits the transmission of excessive loads to the sensor.
2Reliability
If overload protection device is added to the scale, then overload protection is provided, but the housing size and structural volume increase
Solution Approach 1:
The patent merges the overload protection device with the corner load sensor into a single integrated assembly. The corner load sensor serves dual purposes: providing corner load signals for measurement and serving as part of the overload protection mechanism. This combination eliminates the need for separate overload protection components, reducing the overall volume while maintaining protection functionality.
Solution Approach 2:
The patent positions the corner load sensor and overload protection assembly in the space between the parallel guide links, utilizing previously unused spatial volume. By arranging the assembly to extend into the area between the links and fastening it to the side of the load receiver, the design accommodates the overload protection without increasing the external housing dimensions.
3Measurement precision
If corner load sensor is placed before overload protection in force flow direction, then corner load signals can be obtained, but the sensor is subjected to excessive overload forces
Solution Approach 1:
The patent inverts the conventional arrangement by placing the corner load sensor behind (after) the overload protection device in the force flow direction. This reversal ensures that the sensor only experiences loads within its optimal measurement range, as the overload protection device limits the maximum force transmitted to the sensor, thereby protecting it from excessive overload forces while maintaining signal detection capability.
4Measurement precision
If support points of links are made flexible to improve corner load sensor signal, then corner load signals improve, but parallel guide stability and geometry change
Solution Approach 1:
The patent extracts the corner load sensing function from the parallel guide support points and relocates it to a separate corner load sensor assembly. This separation allows the parallel guide to maintain its rigid, stable geometry for accurate weighing while the corner load sensor provides the necessary flexibility and signal output independently, eliminating the conflict between signal quality and guide stability.
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 enables a compact, efficient overload protection system that maintains parallel guide stability and provides enhanced corner load signals without increasing the scale's outer dimensions, ensuring effective overload protection and accurate weight measurement.
Implementation Method 1
the weighing pan is rigidly coupled to the load receiver in the permissible weighing range, but is only elastically coupled to the load receiver when the permissible weighing range is exceeded
Implementation Method 2
corner load sensor being arranged behind the overload safety device in the direction of force flow from the weighing pan to the load receiver and consists of at least three vertical thin areas of material on which strain gauges are applied
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a top-pan balance having a pan, a weighing system, the load cell (4) of which is connected to fixed points (1) on the housing of the weighing system by an upper connecting rod (2) and a lower connecting rod (3) as a parallel guide so as to be movable in the vertical direction, and an overload safety mechanism. The pan is attached to a pan support (8/9) for securing against overload, said support being connected to the load cell (4) by means of an auxiliary parallel guide (15/16) and by means of a biased spring element (17, 18), whereby the pan is quasi rigidly coupled to the load cell (4) in the permissible weighing range, but is only resiliently coupled to the load cell (4) when the permissible weighing range is exceeded, and wherein at least one limit stop is fixed to the housing and limits the elastic deflection of the pan and the pan support in case of overload. According to the invention, an additional corner load sensor is provided between the pan support (8/9) and the load cell (4), the corner load sensor and the overload safety mechanism form a common assembly (7), wherein the corner load sensor is disposed behind the overload safety mechanism in the force flow direction from the pan to the load cell (4). Furthermore, the assembly (7) is attached on the side of the load cell (4) facing the connecting rods (2, 3) and extends into the space between the connecting rods (2, 3). The additional corner load sensor can thus be integrated into the weighing system without requiring additional space and is protected against overload.