Disconnectable All-Wheel Drive Driveline with Synchronizer
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Solution Overview
Problem
Modern all-wheel drive (AWD) drivelines in vehicles are less fuel efficient compared to front-wheel drive (FWD) systems due to components being rotatably driven even when power is not transmitted, leading to increased fuel consumption.
Innovation Solution
A vehicle driveline system with a primary driveline distributing power to a first set of wheels and a secondary driveline with a power take-off unit (PTU) and torque transfer devices, allowing selective coupling and decoupling of power transmission to a second set of wheels, utilizing a synchronizer and clutch to inhibit torque transmission when not needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an all-wheel drive driveline is used to maintain performance, then vehicle traction and handling are improved, but fuel efficiency deteriorates due to continuous rotation of driveline components even when power is not transmitted
Solution Approach 1:
The driveline system dynamically switches between two operational states: a first state where the coupling device connects the primary and secondary drivelines for all-wheel drive operation, and a second state where the coupling device disconnects the secondary driveline to reduce energy consumption during two-wheel drive operation. This dynamic reconfiguration allows the system to adapt to varying driving conditions, providing all-wheel drive capability when needed while improving fuel efficiency during normal driving.
Solution Approach 2:
The driveline system is segmented into a primary driveline and a secondary driveline that can be independently connected or disconnected. The coupling device enables selective engagement of the secondary driveline, allowing the primary driveline to operate independently during two-wheel drive mode, thereby eliminating unnecessary energy consumption from rotating components in the disconnected secondary driveline.
2Use of energy by moving object
If a disconnectable all-wheel drive system is implemented to improve fuel efficiency, then energy consumption is reduced, but device complexity increases due to additional coupling and synchronization mechanisms
Solution Approach 1:
The coupling device serves multiple functions: it connects and disconnects the primary and secondary drivelines, transmits rotational motion between them, and enables synchronization of rotational speeds. By consolidating these functions into a single mechanism, the patent reduces overall system complexity compared to using separate components for each function.
Solution Approach 2:
The synchronizer acts as an intermediary mechanism between the primary and secondary drivelines, mediating the synchronization of their rotational speeds. This intermediary component facilitates smooth engagement and disengagement of the coupling device while maintaining speed coordination, thereby managing the complexity of the disconnectable all-wheel drive system.
3Speed
If continuous rotation of driveline components is maintained to ensure readiness for all-wheel drive, then responsiveness to driving conditions is improved, but energy loss increases
Solution Approach 1:
The coupling device is designed to enable rapid reconnection of the secondary driveline when all-wheel drive capability is needed. By maintaining the coupling device in a ready state that can quickly transition from disconnected to connected, the system achieves preliminary preparation for all-wheel drive operation without requiring continuous rotation of secondary driveline components, thus minimizing energy loss while ensuring responsiveness.
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 system enhances fuel efficiency by enabling operation in two-wheel drive mode with minimal power loss, switching to all-wheel drive when required, thereby reducing fuel consumption and maintaining performance.
Implementation Method 1
The synchronizer includes a plurality of dog teeth formed on the axially movable member and a plurality of dog teeth formed on the input gear in selective engagement with the dog teeth on the axially movable member
Implementation Method 2
The friction clutch is mounted about the differential axis between the second differential and one of the shafts. The friction clutch is configured to selectively interrupt torque transmission between the second differential and the one of the shafts
Data Source
AI summary
A vehicle with a primary driveline that is configured to distribute rotary power to a first set of vehicle wheels and a power transmitting device that can be selectively operated to transmit rotary power to a secondary driveline. The power transmitting device has an input member, which is driven by the primary driveline, and an output member that is selectively coupled to the input member to receive rotary power therefrom. The secondary driveline comprises a differential, a pair of shafts, and a side shaft coupling that selectively interrupts power transmission between the differential and one of the shafts.