Sensor Assembly for Rotor Position Detection in Clutch Actuators
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Solution Overview
Problem
Accurate determination of the axial position and angular position of a rotor in clutch actuators is challenging due to dynamic tolerances and changing air gaps between sensors and permanent magnets, especially when sensors are positioned at a distance from the axis of rotation.
Innovation Solution
A sensor assembly comprising a multiturn sensor and a single turn sensor, positioned at a calculated distance from the axis of rotation, detects the magnetic flux directions in the radial and tangential fields to determine the number of rotations and angular position of a permanently magnetized rotor, minimizing vector sum differences and scatter due to operational tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor is positioned at a distance from the axis of rotation to enable accurate position determination, then the measurement accuracy is improved, but the sensitivity to dynamic tolerances and air gap changes increases
Solution Approach 1:
The patent applies parameter changes by optimizing the radial position of the sensor relative to the permanent magnet. Specifically, the sensor is positioned at a calculated distance from the axis of rotation where the vector sum of radial and tangential flux densities falls within a defined range (12-37 mT). This parameter optimization ensures that the sensor operates in a magnetic field region that is sufficiently strong for accurate measurement while being less sensitive to dynamic tolerances and air gap variations that occur during clutch actuator operation.
2Use of energy by moving object
If the sensor is positioned closer to the permanent magnet to increase magnetic flux density, then the signal strength is improved, but the measurement becomes more sensitive to air gap changes and dynamic tolerances
Solution Approach 1:
The patent changes the spatial parameter of sensor positioning from merely 'close to the magnet' to a specifically calculated radial distance. The sensor is positioned where the vector sum of radial and tangential flux densities is optimized (12-37 mT range), which balances signal strength with reduced sensitivity to operational variations. This parameter optimization resolves the contradiction by finding the optimal compromise point rather than maximizing only one aspect.
3Device complexity
If the sensor is positioned on the axis of rotation, then the setup is simplified, but the ability to determine axial position of actuating units is lost
Solution Approach 1:
The patent transitions the sensor positioning from the axial dimension (on the axis of rotation) to the radial dimension (at a calculated distance from the axis). By moving the sensor radially outward to a specific distance where the magnetic flux vector sum is optimized, the system gains the capability to determine axial position of actuating units while maintaining a relatively simple sensor arrangement. This dimensional change enables both functionality and measurement capability.
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 arrangement provides accurate and stable measurement of rotor positions over time, reducing measurement errors caused by operational tolerances and allowing for precise axial position determination of actuating units in clutch actuators.
Implementation Method 1
The first sensor detects the magnetic field directions of the magnetic flux in the radial magnetic field direction and in the tangential magnetic field direction for determining the number of rotations
Data Source
AI summary
A sensor assembly for determining a number of rotations of a permanent magnet includes a first sensor. The permanent magnet has an axis of rotation, end surfaces lying in an X-Y plane, a central axis, and exactly two poles. The two poles are disposed in the X-Y plane on mutually opposite sides of the permanent magnet so that the permanent magnet is magnetized diametrically. The first sensor is axially fixed and rotationally displaceable relative to the permanent magnet. The first sensor is disposed at a first distance axially offset from the permanent magnet and at a second distance radially offset from the axis of rotation. The second distance is selected so that a vector sum of a radial flux density and a tangential flux density is not less than a first limit value and does not exceed a second limit value.