Differential Gear Sensor Assembly for Axial Position Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing traction modifying differentials face challenges in sensing the locked or unlocked condition due to the axial movement of members within a rotating differential gear case, which is difficult to monitor effectively, especially in severe environments and with petrochemical-based lubricants, and requires additional target members or complex sensor arrangements.
Innovation Solution
A differential gear mechanism with a sensor assembly that utilizes the axial movement of a member already part of the mechanism, such as the inner ramp plate of a ball ramp actuator, to sense changes in state through electromagnetic flux coupling, eliminating the need for additional target members and enabling operation in harsh conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sensor assembly is added to sense the axial movement of members within the rotating differential gear case, then the sensing capability is improved, but the device complexity and package size increase
Solution Approach 1:
The sensor assembly is integrated into the stationary gear case structure, merging the sensing function with the existing housing. The sensor element and wall-like member are incorporated as part of the gear case assembly rather than as separate add-on components, thereby improving sensing capability without proportionally increasing overall device complexity.
Solution Approach 2:
A wall-like member is introduced as an intermediary element between the moving member and the sensor element. This wall-like member modulates electromagnetic flux coupling with the sensor element in response to axial movement of the member being sensed, enabling indirect sensing that avoids direct mechanical contact and reduces complexity.
2Measurement precision
If traditional sensor arrangements are used to monitor axial movement in a rotating gear case, then sensing is achieved, but reliability deteriorates in severe environments and with petrochemical-based lubricants
Solution Approach 1:
The invention replaces mechanical sensor arrangements with an electromagnetic sensing system. The sensor element detects axial movement through electromagnetic flux coupling rather than mechanical contact, eliminating wear and corrosion issues associated with mechanical sensors in severe environments and petrochemical-based lubricants.
Solution Approach 2:
The wall-like member serves as a non-contact intermediary that transmits movement information to the sensor element through electromagnetic flux modulation. This intermediary approach allows the sensor to remain stationary and protected while still accurately sensing the position and movement of rotating components.
3Measurement precision
If additional target members are added to enable sensing, then measurement capability is improved, but the package size increases
Solution Approach 1:
The wall-like member serves multiple functions: it provides structural support within the gear case, defines the sensing zone for the sensor element, and acts as the target for electromagnetic flux coupling. By making this component multi-functional, the invention improves sensing capability without requiring additional dedicated target members that would increase package size.
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
This solution allows for reliable sensing of the differential's state across a broad temperature range and in lubricant environments, reducing package size and enhancing system reliability by leveraging existing mechanical components for feedback.
Implementation Method 1
A sensor assembly is disposed adjacent the one axial end of the gear case and includes a sensor element and a wall-like member disposed axially between the moveable member and the sensor element. The wall-like member includes a non-ferromagnetic portion disposed axially between the sensor element and the moveable member, whereby movement of the moveable member between the first and the second positions results in a corresponding change in the electromagnetic flux coupling the sensor element and the moveable member.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A differential rotation limiting means (35) operable to limit rotation of an output guar (23) relative to a gear case (11 ), and actuation means (55) for actuating the rotation limiting means, from an unactuated to an actuated condition. The rotation limiting means includes a member (47), toward one axial end of the gear case and moveable between a first position, the unactuated condition of said rotation limiting means, and a second position, the actuated condition. A sensor assembly (47,71,73) is adjacent the one axial end of the gear case and includes a sensor element (71 ) and a wall-like member (63,73) between the rotation limiting means (35) and the actuation means. The wall-like member (63,73) includes a non- ferromagnetic portion (73) between the sensor element (71) and the moveable member (47). Movement between the first and second positions results in a corresponding change in the electromagnetic flux (F) coupling the sensor element (71) and the moveable member (47).