Ramp-Style Locking Differential Using Dual Tone-Wheel Phase Detection
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Solution Overview
Problem
Existing differential gear mechanisms lack an efficient and reliable method to detect the locked or unlocked state of electronically actuated locking differentials, which is crucial for vehicle traction and performance, especially during turns or varying terrain conditions.
Innovation Solution
An electronically locking differential assembly that includes a differential case, side gears, a lock actuation mechanism with a ramp plate and tone wheels, and sensors to determine the locked or unlocked state by sensing the relative position of teeth on the differential case and ramp plate, allowing the controller to output a signal indicating the lock status.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a locking mechanism is added to the differential to enable locked state, then traction control capability is improved, but device complexity increases
Solution Approach 1:
A ramp plate is introduced as an intermediary component between the electromagnetic coil and the side gears. The ramp plate converts electromagnetic force into mechanical locking action, mediating the interaction between the actuator and the differential mechanism, thereby enabling locking function while maintaining modular design
Solution Approach 2:
The patent replaces complex mechanical locking mechanisms with an electromagnetic coil that actuates the ramp plate. This substitution of electromagnetic actuation for purely mechanical systems reduces the number of moving parts and simplifies the overall device structure while maintaining reliable locking capability
2Measurement precision
If lock status detection is implemented using tone wheels and sensors, then lock status detection accuracy is improved, but device complexity increases
Solution Approach 1:
Tone wheels with teeth patterns are used to create optical copies or representations of the mechanical state. The sensors detect the position of teeth on the tone wheels, which correspond to the lock status, providing an optical copy of the mechanical configuration for electronic interpretation
Solution Approach 2:
The tone wheels serve as intermediary components that translate mechanical position into detectable optical signals. Rather than directly sensing mechanical contact, the system uses the tone wheels as mediators to convert physical state into sensor-readable patterns, improving detection accuracy while isolating the sensing system from mechanical complexity
3Reliability
If two tone wheels are used for lock detection, then lock status determination reliability is improved, but manufacturing cost increases
Solution Approach 1:
Both tone wheels serve multiple functions: they are integral to the locking mechanism structure and simultaneously serve as encoding elements for lock status detection. This multi-functionality reduces the need for separate detection components, offsetting the cost of using two tone wheels through functional consolidation
Solution Approach 2:
The existing structural components (the tone wheels with their teeth patterns) provide their own detection function. The teeth patterns on the tone wheels automatically encode the mechanical state, and the sensors simply need to read these pre-existing patterns, allowing the components to serve both structural and detection purposes without additional specialized parts
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 determination of the differential's lock status, enhancing driver control and vehicle behavior prediction by providing a reliable method to sense phase lag between the differential case and ramp plate, thus improving traction management.
Implementation Method 1
a pickup sensor that senses a position of the plurality of teeth
Data Source
AI summary
An electronically locking differential assembly according to the present disclosure includes a differential case, a first and second side gear, a lock actuation mechanism, a first and second tone wheel, a first and second pickup sensor and a controller. The lock actuation mechanism includes a ramp plate that selectively moves between a locked state and an unlocked state. The first tone wheel has a first plurality of teeth formed on the differential case. The second tone wheel has a second plurality of teeth formed on the ramp plate. The first pickup sensor senses a position of the first plurality of teeth. The second pickup sensor senses a position of the second plurality of teeth. The controller determines whether the lock actuation mechanism is in the locked or unlocked state based on the respective positions of the first and second plurality of teeth.