GMR Target Wheel Sensing for Hidden Transmission Shaft Rotation
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Solution Overview
Problem
Existing systems for sensing the speed and direction of a rotating shaft, such as an input shaft in a vehicle transmission, face challenges due to the construction of the transmission, which makes it difficult for sensors to observe the shaft's rotation effectively.
Innovation Solution
A transmission system that includes a target wheel with voids and a giant magnetoresistance (GMR) sensor spaced apart to observe the voids, allowing the sensor to determine the rotation speed and direction of the shaft through the GMR effect, even when a non-ferrous torque transfer housing is present between the sensor and the target wheel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional sensor system is used to observe the input shaft rotation, then the shaft rotation speed can be determined, but the transmission construction makes it difficult to observe the input shaft as it rotates
Solution Approach 1:
A target wheel is introduced as an intermediary component that is easier to access and observe than the input shaft itself. The target wheel rotates with the input shaft through magnetic coupling, allowing the sensor to detect rotation by observing the target wheel's position changes rather than directly observing the shaft
Solution Approach 2:
The system replaces direct mechanical observation of the input shaft with a magnetic field-based detection system. A Hall effect sensor detects changes in magnetic field position caused by the rotating target wheel, substituting mechanical observation with electromagnetic sensing
2Measurement precision
If magnets are included in the target wheel to aid detection, then detection capability is improved, but manufacturing complexity and weight increase
Solution Approach 1:
The magnets are extracted from the target wheel and placed in the sensor assembly instead. This allows the target wheel to be a simple ferromagnetic or non-magnetic component that can be easily manufactured, while the magnetic field generation is handled by the sensor system
Solution Approach 2:
Instead of using magnets in the target wheel to create magnetic signatures for detection, the system inverts the approach by using the sensor's own magnetic field and detecting disturbances or position changes caused by the ferromagnetic target wheel material itself
3Measurement precision
If a ferrous target wheel is used, then magnetic field interaction is enhanced, but energy loss increases
Solution Approach 1:
The system changes the material parameter of the target wheel from ferrous to non-magnetic materials such as aluminum or plastic. This reduces magnetic energy loss and eddy current effects while maintaining detection capability through alternative magnetic field interaction mechanisms
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
Enables accurate detection of the rotation speed and direction of the input shaft, reducing manufacturing complexity and weight, while minimizing energy loss and improving fuel efficiency by using a magnet-free target wheel and optimizing the magnetic field detection capability of the GMR sensor.
Implementation Method 1
The giant magnetoresistance (GMR) sensor is configured to observe the at least one void of the target wheel to determine a rotation speed of the shaft based on a giant magnetoresistance (GMR) effect
Data Source
AI summary
A transmission system associated with a vehicle includes a shaft to rotate about an axis of rotation. The shaft is coupled to a gear set. The transmission system includes a target wheel to be coupled to the gear set and to rotate with the gear set. The target wheel includes at least one void. The transmission system includes a giant magnetoresistance (GMR) sensor spaced apart from the target wheel by a gap. The giant magnetoresistance (GMR) sensor is configured to observe the at least one void of the target wheel to determine a rotation speed of the shaft based on a giant magnetoresistance (GMR) effect. The transmission system further includes a rotating shell located in the gap between the target wheel and the giant magnetoresistance (GMR) sensor.