Locking Differential Sensor Assembly With Stationary Case-Mounted Sensing
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Solution Overview
Problem
Existing electronically actuated locking differentials face challenges in sensing the locked state due to non-contacting sensors on rotating armatures, leading to increased costs and durability concerns.
Innovation Solution
A sensor assembly with a sensor housing, switch element, and sense element, such as a magnet, is configured to determine the position of the armature relative to the stator, using a detent mechanism and flexible housing to isolate the sensor from the armature, allowing for reliable state detection without direct contact and reduced wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sensor is attached to the rotating armature to detect the locked state, then the ability to electronically sense the differential state is improved, but the cost increases and durability concerns arise due to wear and non-contacting sensor requirements
Solution Approach 1:
Instead of attaching the sensor to the rotating armature, the patent inverts the arrangement by fixing the sensor assembly to the stationary differential case and allowing a sense element (magnet) to move with the armature. This inversion eliminates the need for the sensor to withstand rotation and wear, thereby improving reliability while maintaining detection capability.
Solution Approach 2:
The patent introduces a magnet as an intermediary element that couples the moving armature to the sensing mechanism. The magnet serves as a mediator that transfers positional information from the rotating armature to the stationary sensor without requiring direct mechanical contact between the sensor and armature, thus improving durability while maintaining measurement precision.
2Measurement precision
If a sensor is attached to the rotating armature to detect the locked state, then the ability to electronically sense the differential state is improved, but the cost increases due to non-contacting sensor requirements
Solution Approach 1:
The patent inverts the sensor mounting approach, fixing the sensor to the stationary case rather than the rotating armature. This allows the use of simpler, less expensive sensors that do not need to be designed for rotational environments, thereby reducing manufacturing costs while maintaining the ability to detect differential state electronically.
Solution Approach 2:
By using a magnet as an intermediary, the patent enables the use of cost-effective stationary sensors instead of expensive non-contacting sensors that would be required if mounted on the rotating armature. The magnet provides a simple, low-cost mechanism for transmitting positional information.
3Measurement precision
If a sensor is attached to the rotating armature to detect the locked state, then the ability to electronically sense the differential state is improved, but wear and durability become a concern
Solution Approach 1:
The patent eliminates sensor wear by inverting the mounting configuration - the sensor remains stationary on the differential case while only a simple magnet moves with the armature. This inversion removes the harmful factor of wear from the sensor, as stationary sensors do not experience mechanical degradation from rotation or contact.
Solution Approach 2:
The magnet serves as a wear-free intermediary that carries positional information without subjecting the sensor to harmful wear mechanisms. The magnet can freely move with the rotating armature without causing wear to the stationary sensor, thereby eliminating durability concerns.
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 enables accurate detection of the differential's locked or unlocked state, reducing costs and improving durability by isolating the sensor from harsh environments and eliminating parasitic losses during locking, while maintaining ease of installation and minimal mass addition.
Implementation Method 1
The sense element is a magnet. The sensor assembly is configured to change state based on a position of the sense element
Data Source
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AI summary
A sensor assembly configured for use with a locking differential received in a differential case includes a sensor housing, a switch element and a sense element. The sensor assembly is configured to determine a position of an armature in relation to a stator. The armature moves relative to the stator between engaged and disengaged positions corresponding to the locking differential being in a locked and unlocked state. The sensor housing is coupled relative to the differential case of the locking differential. The switch element is disposed in the sensor housing. The sense element moves with the armature. The sensor assembly is configured to change state based on a position of the sense element.