Magnetic Shield for Linear Position Sensor in Dual Clutch Transmission
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Solution Overview
Problem
In dual clutch transmissions, the proximity of powerful solenoids to speed and position sensors leads to magnetic field disturbances that adversely impact sensor output signals, making it challenging to relocate either the solenoids or sensors due to size and packaging constraints.
Innovation Solution
A linear position sensor assembly with a magnetic shield, comprising a pair of magnetic field sensors spaced apart by a high magnetic permeability metal bar, enclosed by a cover of high magnetic permeability material, minimizes interference from adjacent electrical and electromagnetic devices, using a permanent magnet that translates with the clutch actuator component.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If solenoids are located proximate to sensors to meet packaging constraints, then device compactness is improved, but magnetic field interference increases causing sensor signal degradation
Solution Approach 1:
A magnetic shield made of high permeability material is introduced as an intermediary component between the solenoid and the sensor. This shield intercepts and redirects magnetic field lines, preventing them from reaching the sensor while allowing the solenoid and sensor to remain in their required proximity for compact transmission design.
Solution Approach 2:
The magnetic shield is strategically positioned only in the specific region where magnetic interference occurs between the solenoid and sensor, rather than enclosing the entire transmission. This localized approach provides targeted protection while minimizing additional space requirements.
2Measurement precision
If sensors are relocated to avoid magnetic interference, then signal quality is improved, but sensor positioning flexibility is reduced due to narrowly defined sensing locations
Solution Approach 1:
The magnetic shield serves as a protective intermediary that allows the sensor to remain in its optimal positioning for accurate measurement while blocking harmful magnetic fields. This eliminates the need to relocate the sensor to suboptimal positions.
3Measurement precision
If solenoids are relocated to reduce magnetic interference, then sensor signal quality is improved, but power flow path constraints are violated
Solution Approach 1:
The magnetic shield provides a localized solution to the electromagnetic interference problem, allowing both the solenoid and sensor to remain in their functionally required positions without compromising power flow paths or requiring complex system reconfiguration.
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 high-linearity, low-noise output signals with no deadband, effectively suppressing electromagnetic interference and allowing accurate position sensing of clutch engagement and disengagement in dual clutch transmissions.
Implementation Method 1
The sensors and metal bar are enclosed, i.e., surrounded on three sides, by a cover or shield of high magnetic permeability material such as steel or mu metal
Implementation Method 2
a magnetic interference shield which minimizes interference (noise) from adjacent electrical and electromagnetic devices, particularly solenoids
Data Source
AI summary
A linear position sensor assembly having a magnetic shield minimizes interference (noise) from adjacent electrical and electromagnetic devices, particularly solenoids. The sensor assembly includes a permanent magnet linear contactless displacement (PLCD) sensor comprising a pair of magnetic field sensors which are spaced apart by a member of high magnetic permeability such as a metal bar. The sensors and metal bar are enclosed, i.e., surrounded on three sides, by a cover or shield of high magnetic permeability material such as steel or mu metal, for example. A permanent magnet is disposed in sensed proximity to the sensors and translates with a clutch actuator component. When the clutch actuator component translates axially, the two field sensors provide a signal to associated electronics having high linearity, low noise and no deadband.