Variable Pitch Linear Displacement Sensor for High Sensitivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing linear contactless displacement sensors face limitations in sensitivity and packaging space due to the degrading magnetic field strength as the magnet moves further from the coils, leading to reduced voltage changes for given displacements, which affects accuracy and increases the weight and kinematic interference of vehicles.
Innovation Solution
A linear contactless displacement sensor assembly with a rotating sleeve having a variable thread pitch, where the sleeve rotates about a linearly translating shaft, allowing a sensor target with a tooth to move along a linear track, enhancing sensitivity and accuracy by varying the thread pitch to match different operational conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor length is increased to maintain sensitivity at larger magnet displacements, then the measurement precision is improved, but the device complexity and packaging space requirements increase
Solution Approach 1:
The patent applies parameter changes by varying the thread pitch along the length of the sleeve. The thread pitch is smaller near the sensor coils and progressively larger at greater distances. This parameter variation compensates for the degrading magnetic field strength, maintaining consistent sensitivity across the full range of motion without requiring increased sensor length.
Solution Approach 2:
The patent implements local quality by making different sections of the sleeve have different thread pitches. The region closer to the coils has a finer pitch for high sensitivity where the magnetic field is strongest, while regions farther away have coarser pitches appropriate for the weaker field strength, optimizing performance locally throughout the sensor assembly.
2Measurement precision
If the sensor length is increased to maintain sensitivity, then the measurement precision is improved, but the weight and kinematic interference increase
Solution Approach 1:
By changing the thread pitch parameter along the sleeve length, the patent maintains measurement precision without increasing sensor length. This prevents the associated weight increase that would result from a longer sensor assembly, directly resolving the contradiction between sensitivity and weight.
3Manufacturing precision
If the thread pitch is uniform throughout the sleeve, then the manufacturing precision is improved, but the sensitivity varies with magnet displacement distance
Solution Approach 1:
The patent applies local quality by making the thread pitch non-uniform, with different pitches in different regions of the sleeve. This deliberate local variation compensates for the spatial variation in magnetic field strength, maintaining consistent sensitivity across all displacement positions while accepting the increased manufacturing complexity of variable pitch threading.
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 variable thread pitch design improves sensitivity and accuracy of the sensor, particularly during high-speed maneuvers, while reducing the need for increased sensor length, thus minimizing weight and kinematic interference in vehicles.
Implementation Method 1
a magnet passing over coils changes the magnetic field around the coils, creating a voltage
Implementation Method 2
A tooth is disposed in the threading and fixed on a linear track such that the tooth moves linearly as the sleeve rotates
Data Source
AI summary
A linear contactless displacement sensor assembly is provided. The sensor assembly can include a shaft configured to translate linearly, and a sleeve rotatably coupled about the shaft and linearly fixed such that the shaft can linearly translate through the sleeve as the sleeve rotates. The sleeve includes an outer surface having a threading that varies in pitch. A tooth is disposed in the threading and fixed on a linear track such that the tooth moves linearly as the sleeve rotates. A sensor is configured to sense a location of the tooth along the linear track. This allows the sensor assembly to measure an amount of linear movement and a corresponding amount of rotation of the sleeve.