Planetary Differential Clutch AWD Disconnect Axle
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Solution Overview
Problem
There is a need for improved disconnectable drivelines in all-wheel drive (AWD) vehicles to minimize driveline losses and efficiently manage torque distribution between the primary and secondary drivelines, particularly in conditions where no drive torque is transmitted to the rear wheels or rear differential.
Innovation Solution
The implementation of a drivetrain system that includes a planetary differential with two clutches, allowing for selective coupling and decoupling of components to manage torque distribution, including a first clutch that couples or decouples the sun gear with the second output member and a second clutch that couples or decouples the planet carrier with the second output member, enabling modes for disconnecting, limited slip, and locking operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a disconnect system is incorporated to uncouple components of the secondary driveline, then driveline losses are minimized, but device complexity increases
Solution Approach 1:
The secondary driveline is segmented into multiple controllable sections through the planetary differential mechanism. The sun gear, planet carrier, and ring gear can be independently controlled via first and second clutches, allowing selective disconnection of different driveline components. This segmentation enables precise control over which components remain connected to minimize driveline losses while maintaining overall system manageability.
Solution Approach 2:
The disconnect system employs dynamic clutch control to adaptively connect and disconnect driveline components based on operating conditions. The first clutch dynamically couples or decouples the sun gear from the second output member, while the second clutch dynamically couples or decouples the planet carrier from the second output member. This dynamic control allows the system to respond to varying torque requirements and minimize energy losses in real-time.
2Productivity
If a planetary differential with two clutches is used to manage torque distribution, then torque distribution efficiency is improved, but device complexity increases
Solution Approach 1:
The planetary differential mechanism serves multiple functions within a single integrated structure. It simultaneously provides torque distribution to the secondary driveline, enables limited-slip differential action through the differential gear set, and allows for locked differential operation when both clutches are engaged. This multi-functionality eliminates the need for separate mechanisms for each function, improving torque distribution efficiency while controlling overall device complexity.
Solution Approach 2:
The planetary differential acts as an intermediary mechanism between the input member and the second output member. The differential gear set mediates torque distribution between the sun gear and planet carrier, allowing smooth torque management. The first and second clutches serve as intermediary control elements that regulate the engagement and disengagement of different torque paths, enabling efficient torque distribution without direct rigid coupling.
3Reliability
If disconnect modes are implemented to prevent back-driving, then reliability is improved, but ease of operation decreases
Solution Approach 1:
The disconnect system is designed to automatically respond to back-driving conditions through the inherent mechanical characteristics of the planetary differential. When the secondary driveline attempts to back-drive, the planetary gear arrangement and clutch configuration automatically disengage the affected components, preventing damage without requiring external intervention. This self-service capability improves reliability while maintaining ease of operation.
Data Source
AI summary
An all-wheel drive vehicle drivetrain can include an input member, first and second output members, a planetary differential, a first clutch, and a second clutch. The differential can include an internal gear, a carrier, a sun gear, and a differential gear set. The internal gear can be coupled to the input member to receive input torque about an axis. The carrier can be coupled to the first output for common rotation about the axis. The differential gear set can receive input torque from the internal gear and output differential torque to the carrier and the sun gear. The first clutch can be operable to selectively couple and decouple the sun gear with the second output member for common rotation. The second clutch can be operable to selectively transmit torque between the carrier and the second output member.