Speed Sensor Magnetic Weight Counterbalancing
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Solution Overview
Problem
Conventional speed sensors face limitations in achieving low natural frequency and robust electrical connections due to material stress and sagging leaf springs, which restrict the maximum working stroke and increase material stress.
Innovation Solution
The speed sensor design counterbalances the weight of the dynamic part using magnet arrays, eliminating the need for springs and reducing magnetic rigidity, allowing for a larger measurement stroke while minimizing material stress and achieving low natural frequency through a combination of magnet arrays and optional added mass, along with damping mechanisms using short-circuited coils or capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the dynamic part is supported by leaf springs to carry its weight, then the structure is simple and reliable, but the material stress increases and the maximum working stroke is reduced
Solution Approach 1:
The patent applies the anti-weight principle by using a magnet array that generates a magnetic bias force equal and opposite to the gravitational force on the dynamic part. This counterbalances the weight, eliminating the need for leaf springs to support the dynamic part's weight, thereby reducing material stress and increasing the maximum working stroke while maintaining structural reliability
2Device complexity
If leaf springs are used to support the dynamic part, then the structure is mechanically simple, but the natural frequency cannot be reduced below a certain limit
Solution Approach 1:
By counterbalancing the weight with magnetic force, the system eliminates the mechanical constraints of leaf springs, allowing the natural frequency to be reduced below the limits imposed by spring-based support structures
Solution Approach 2:
The patent replaces the mechanical leaf spring support system with a magnetic field-based weight counterbalancing system. This substitution allows for lower natural frequencies and eliminates the mechanical constraints that limit the performance of spring-based systems
3Length of moving object
If the dynamic part is moved freely without spring support, then the working stroke is maximized, but the electrical connection becomes less robust
Solution Approach 1:
The magnetic counterbalancing system enables free movement of the dynamic part with minimal mechanical constraints, maximizing the working stroke while the magnetic field provides stable positioning that facilitates more robust electrical connections
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 design enhances the speed sensor's robustness and measurement capabilities by maintaining a low natural frequency and reducing material stress, enabling a full stroke utilization and effective damping of vibrations.
Implementation Method 1
the first and second parts, which are axially movable relative to one another. One of the parts is static and the other part is dynamic, and one of the parts comprises a measuring coil for measuring the speed at which the two parts are displaced relative to each other. The first part comprises a first magnet array and the second part a second magnet array, which magnet arrays exert a magnetic force on each other
Implementation Method 2
one of the parts comprises a measuring coil for measuring the speed at which the two parts are displaced relative to each other
Implementation Method 3
along with damping mechanisms using short-circuited coils or capacitors
Data Source
AI summary
A speed sensor has a static part and a dynamic part arranged concentrically inside the static part. The static part has two permanent magnets and the dynamic part has two further permanent magnets. The magnet is oriented reversely to the further magnets. The magnets are tuned to each other so that gravity on the dynamic part is counteracted by the magnetic force on the dynamic part. As a result, the weight of the dynamic part need not be carried by springs and the dynamic part can move freely so that the full stroke can be used for measuring accelerations and the natural frequency is low. The static part further includes a measuring coil for measuring the displacement of the dynamic part and for the radial positioning of the dynamic part this part is connected to the static part by means of leaf springs.