Locking Differential Position Sensing Under Ring Gear Rotation
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Solution Overview
Problem
The packaging constraints of axle integrators in differential assemblies make it challenging to include a position sensor that accurately indicates the locked or unlocked state of the differential while allowing rotation of the ring gear without measurement inaccuracies.
Innovation Solution
An electronic locking differential assembly with a sensor assembly attached to the armature, featuring a notch on the retaining ring and anti-rotation tabs, allows axial movement for locking and unlocking, while the sensor housing extends beyond the armature for accurate position detection and clearance from rotating components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a position sensor is included in the differential assembly to measure armature position, then measurement precision is improved, but device complexity increases and packaging constraints are violated
Solution Approach 1:
The position sensor is integrated into the existing electronic actuator assembly rather than being a separate component. The sensor utilizes the same magnetic field environment created by the actuator components, merging measurement functionality into the actuation mechanism itself. This reduces overall device complexity while maintaining measurement precision.
Solution Approach 2:
The electronic actuator assembly serves dual purposes: it provides the locking/unlocking force through electromagnetic actuation and simultaneously houses the position sensor that measures armature displacement. This multi-functionality eliminates the need for separate sensor mounting structures, addressing packaging constraints while enabling precise measurement.
2Measurement precision
If the sensor measures axial position of the armature, then measurement precision is improved, but reliability deteriorates due to rotation of the ring gear causing measurement inaccuracies
Solution Approach 1:
The sensor is positioned in a specific location where it measures only axial displacement of the armature while being shielded from or insensitive to rotational movements. The measurement field is localized to the axial direction, creating a measurement zone that excludes rotational interference from the ring gear.
Solution Approach 2:
Instead of trying to prevent rotation during measurement or compensate for rotational effects, the sensor is designed to be inherently insensitive to rotation by orienting its measurement axis perpendicular to the rotational movement. The sensor detects axial position changes while ignoring radial/rotational components, inverting the approach from active compensation to passive immunity.
Data Source
AI summary
An electronic locking differential assembly includes a ring gear including at least one bore formed therein. An electronic actuation mechanism is positioned behind the ring gear on one side of the ring gear. A retaining ring includes a notch formed thereon on an outer circumference of the retaining ring. A portion of the electronic actuation mechanism is disposed in the notch. A lock plate is positioned on a side of the ring gear opposite the electronic actuation mechanism. The retaining ring includes a bore formed therein and a fastener disposed in the bore. The fastener is coupled to the retaining ring and passes through the at least one bore of the ring gear. The fastener is coupled to the lock plate wherein the electronic actuation mechanism is axially connected to the lock plate selectively locking and unlocking the differential.