Tocodynamometer Transducer Flat Spring Symmetry
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Prior tocodynamometer transducers suffer from mechanical instability, limited dynamic range, inaccurate readings due to uneven spring constants, heat welding stresses, ferrite core protrusion causing electromagnetic interference, and under-voltage semiconductor operation, leading to non-linear outputs and reliability issues.
Innovation Solution
The improved tocodynamometer transducer features a flat spring with symmetrical spring ribs for consistent spring constant, a solid ferrite core within the LVDT windings, and a design that prevents ferrite core protrusion, along with a semiconductor circuit optimized for +4.0V DC operation, ensuring linear output and enhanced mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a flat spring with one axis of equal spring constant is used, then the transducer structure is simple, but the readings become inaccurate when force is applied to different locations on the diaphragm
Solution Approach 1:
The patent applies asymmetry by transitioning from a flat spring with one axis of equal spring constant to a curved spring with two axes of equal spring constant. The curved spring is designed with symmetrical spring ribs that provide equal spring constant in both radial and tangential directions, creating a balanced mechanical response regardless of where force is applied on the diaphragm surface.
2Strength
If heat welding is used to affix the plastic adapter to the flat spring, then the adapter is securely attached, but stresses are introduced in the spring causing variations in spring constant and permanent offset
Solution Approach 1:
The patent replaces the heat welding process with a mechanical interference fit system. The plastic adapter is designed with interference fit features that mechanically secure it to the curved spring without requiring heat welding. This substitution eliminates the thermal stresses and mechanical deformations introduced by welding, while maintaining secure attachment through precise mechanical dimensions and interference fit design.
3Power
If the ferrite core length exceeds the LVDT transformer wire windings boundary, then the magnetic coupling is enhanced, but the readings become non-linear and inaccurate due to electromagnetic interference
Solution Approach 1:
The patent applies parameter changes by precisely controlling the ferrite core length to match the LVDT transformer wire winding boundary. The ferrite core is designed with specific dimensional parameters that ensure it extends just enough to provide adequate magnetic coupling while remaining within the windings boundary. This parameter optimization balances magnetic coupling strength with reading linearity, preventing electromagnetic interference while maintaining sufficient magnetic flux coupling.
4Power
If the ferrite core length is more than double the required size, then the magnetic coupling is sufficient, but the LVDT output drifts due to electromagnetic interference
Solution Approach 1:
The patent optimizes the ferrite core length parameter to achieve the minimum sufficient length for adequate magnetic coupling while preventing excessive protrusion that causes electromagnetic interference. The ferrite core length is carefully dimensioned to extend just enough within the LVDT transformer to maintain sufficient magnetic flux coupling, avoiding the instability and drift caused by overly long cores that protrude beyond the windings boundary.
5Stability of the object's composition
If a raised step collar is added to the plunger to limit ferrite core range of motion, then the ferrite core is constrained, but the dynamic range is limited and positioning becomes difficult
Solution Approach 1:
The patent removes the raised step collar feature from the plunger design. Instead of using a step collar to limit ferrite core range of motion, the invention relies on the natural mechanical constraints of the LVDT transformer structure and the interaction between the ferrite core and the diaphragm assembly. This extraction of the step collar feature eliminates the artificial range limitation while maintaining stable ferrite core positioning through the inherent mechanical interface between the plunger, diaphragm, and transformer components.
6Use of energy by moving object
If the supply voltage is fixed at +4.0V DC but semiconductor components require minimum +5.0V DC, then the circuit operates at reduced voltage, but semiconductor performance varies and accuracy fluctuates
Solution Approach 1:
The patent changes the semiconductor component selection parameters to match the fixed +4.0V DC supply voltage. Instead of using semiconductors rated for minimum +5.0V DC operation, the invention selects semiconductor components that are optimized for +4.0V DC operation. This parameter change in component specification ensures stable and accurate semiconductor performance at the fixed supply voltage, eliminating performance variations and accuracy fluctuations that occur when operating below the minimum rated voltage.
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 a stable, linear output across a wider dynamic range (0-500 gm) with improved accuracy and reliability, reducing drift and electromagnetic interference, and extending the transducer's operational lifespan.
Implementation Method 1
The ultrasound signal is received by piezo-electric crystals and appropriately filtered
Implementation Method 2
A Linear Variable Differential Transformer (LVDT) in the transducer design
Data Source
AI summary
The present invention relates to an improved tocodynamometer transducer that exhibits increased mechanical stability, dynamic range, accuracy, and reliability. Improvement components include top and bottom enclosures, plunger, ferrite core, LVDT transformer, transformer housing, flat spring, and other components. The flat spring includes four spring ribs that are symmetrical, curvilinear in shape, identical in path length, separated by an air gap, and equally spaced between the outer ring, inner ring, and the spring ribs that are adjacent. The spring constant is identical along two or more axes improving the accuracy of the improved tocodynamometer transducer. The ferrite core travel length is increased and mechanically constrained to remain between the LVDT transforming winding increasing the dynamic range and the linearity of the voltage output of the improved tocodynamometer transducer.