Transfer Case Locking Mechanism for Positive Torque Coupling
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Solution Overview
Problem
Current transfer cases lack a mechanism for positively coupling primary and secondary output shafts and require separate actuators for operating the plate clutch and gear reduction, limiting their ability to seamlessly switch between drive modes and ranges.
Innovation Solution
A transfer case design incorporating a locking mechanism and a common actuator system that operates the plate clutch and gear reduction, allowing for sequential rotation stages to switch between drive ratios and modes, including a secondary torque locking mechanism for positive coupling in four-wheel drive operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a locking mechanism is added to positively couple the primary and secondary output shafts, then torque transfer reliability is improved, but device complexity increases
Solution Approach 1:
The locking mechanism is integrated with the existing plate clutch assembly, where the locking ring works in conjunction with the plate clutch to provide both friction-based torque transfer and positive mechanical locking. This merging of functions reduces the need for entirely separate locking components and simplifies the overall structure while improving reliability.
Solution Approach 2:
The locking ring acts as an intermediary component that provides positive mechanical coupling between the primary and secondary output shafts. It engages with splines on the shafts to create a direct mechanical connection, ensuring reliable torque transfer without requiring completely separate locking mechanisms.
2Ease of operation
If separate actuators are used for operating the plate clutch and gear reduction, then operational control is improved, but device complexity and cost increase
Solution Approach 1:
A single actuator is designed to perform multiple functions by operating different components at different stages. The actuator first operates the gear reduction mechanism, then subsequently operates the plate clutch and locking ring through sequential engagement, eliminating the need for separate actuators while maintaining operational control.
Solution Approach 2:
The actuator is designed to perform preliminary action by first engaging the gear reduction mechanism before engaging the plate clutch and locking ring. This sequential operation ensures that the system is properly prepared for torque transfer, with the gear reduction already in place before the friction and locking mechanisms engage.
3Adaptability or versatility
If sequential rotation stages are implemented for switching between drive ratios and modes, then adaptability is improved, but device complexity increases
Solution Approach 1:
The system employs dynamic sequential engagement of different mechanisms rather than static fixed configurations. The actuator dynamically switches between operating the gear reduction, plate clutch, and locking ring based on the required drive mode, allowing adaptability without requiring complex mechanical linkages for each possible configuration.
Solution Approach 2:
The actuation process is segmented into distinct stages: first stage for gear reduction engagement, second stage for plate clutch engagement, and third stage for locking ring engagement. This segmentation allows each function to be controlled independently through the single actuator, providing adaptability while keeping the control mechanism relatively simple.
Data Source
AI summary
A transfer case includes a housing, along with an input shaft, a primary output shaft, a secondary output shaft, and a secondary torque transfer mechanism, each disposed at least partially within the housing. The input shaft is configured to couple to the primary output shaft to transfer torque thereto. The secondary torque transfer mechanism includes a rotating member coupled to the secondary output shaft and a locking mechanism. The locking mechanism includes a locking ring, a fork member engaging the locking ring, and a slide shaft coupled to the fork member and configured to slide the locking ring to positively couple the primary output shaft to the rotating member to transfer torque to the secondary output shaft. The housing includes an aperture axially configured to receive an elongated tool configured to be rotated manually external to the housing for engaging and moving the slide shaft to the second position.