Actuator Sensor Assembly with Biasing Member for Run-Out Compensation
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Solution Overview
Problem
Existing sensing systems for actuator assemblies in locking gear sets, such as power takeoff units and differentials, face issues with mechanical and magnetic proximity sensors due to run-out of moving parts, leading to accuracy problems and noise caused by axial displacement during rapid rotation.
Innovation Solution
A sensing system comprising a magnet holding plate with a biasing member and raised portions, a pressure plate with a spring biasing mechanism, and a sensor assembly that includes a Hall sensor to detect the position of a sensor target, which maintains alignment and reduces noise by limiting axial movement of the pressure plate, thereby enhancing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If magnetic proximity sensors are used to detect actuator position, then non-contact sensing is achieved, but accuracy deteriorates due to run-out of moving parts causing axial displacement
Solution Approach 1:
A non-magnetic spacer is introduced as an intermediary component between the rotating pressure plate and the magnetic sensor. This spacer acts as a mediator that transfers the rotational position information to the sensor while isolating the sensor from the harmful effects of run-out and axial displacement. The spacer's non-magnetic property prevents interference with the magnetic field, while its rigid structure provides a stable reference surface for accurate position detection.
2Measurement precision
If mechanical positional sensors are used to detect actuator position, then direct mechanical contact sensing is achieved, but wear and mounting issues occur
Solution Approach 1:
The patent replaces mechanical contact-based position sensing with a magnetic field-based sensing system. Instead of using mechanical sensors that physically contact the rotating components, a magnetic sensor detects position through the magnetic field generated by magnets mounted on the pressure plate. This substitution eliminates wear from mechanical contact while maintaining accurate position detection capability.
3Measurement precision
If the sensor is positioned close to the rotating pressure plate for accurate detection, then measurement precision improves, but sensitivity to run-out and axial displacement increases
Solution Approach 1:
The non-magnetic spacer serves as a protective intermediary that allows the sensor to be positioned close to the rotating pressure plate for accurate detection while shielding the sensor from the harmful effects of run-out and axial displacement. The spacer absorbs and isolates these mechanical imperfections, preventing them from directly affecting sensor readings.
Solution Approach 2:
The system creates a copy of the rotational position information through the magnetic field, which is then detected by the sensor. Instead of directly sensing the physical position of the pressure plate, the sensor detects the magnetic field pattern that copies the positional information. This copying mechanism allows accurate detection while being immune to mechanical run-out and axial displacement.
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 proposed sensing system improves accuracy by minimizing the impact of run-out on sensor readings, reducing noise and error motions, and maintaining precise detection of the locking gear set's position despite rapid rotation.
Implementation Method 1
The sensor assembly includes a sensor and a sensor housing positioned radially outward from the pressure plate and magnet holding plate
Data Source
AI summary
An actuator assembly with a sensor system that is less sensitive to run-out out of moving parts. The sensing system includes a magnet holding plate, a pressure plate, a sensor target and a sensor assembly. The magnet holding plate includes an aperture defining an inner surface, an outer surface, a raised portion along the inner surface, a biasing member positioned along the inner surface in the raised portion, and a flange positioned on the outer surface. The pressure plate includes an outer surface of the pressure plate is positioned underneath the raised portion of the magnet holding plate, axially between the raised portion and the biasing member. The sensor target is attached to the flange of the magnet holding plate. The sensor assembly includes a sensor and a sensor housing positioned radially outward from the pressure plate and magnet holding plate.