Active Dry Disconnect System for Hypoid Gearset Energy Loss Reduction
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Solution Overview
Problem
Existing vehicle drivelines experience energy losses due to continuous rotation of hypoid gearsets, which convert transferred energy into heat, reducing efficiency and increasing fuel consumption.
Innovation Solution
A driveline system with selectively disconnectable hypoid gearsets using active power disconnection devices, such as dry friction clutches, to prevent the hypoid gearsets from rotating when not transferring torque, thereby reducing churning losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If hypoid gearsets continuously rotate during all modes of operation, then torque transfer capability is maintained, but energy losses increase due to churning and parasitic effects
Solution Approach 1:
The patent applies dynamics by making the hypoid gearset rotation state changeable - it can rotate when torque transfer is needed and be disconnected when it is not. The power take-off unit with disconnect capability allows the ring gear to dynamically transition between rotating and non-rotating states based on driveline mode, resolving the contradiction between maintaining torque transfer capability and reducing energy losses.
Solution Approach 2:
The driveline is segmented into separate controllable units with individual disconnect capabilities. Each power take-off unit can be independently disconnected from its associated hypoid gearset, allowing selective engagement/disengagement. This segmentation enables the system to reduce energy losses in non-driven axles while maintaining torque transfer in active axles.
2Power
If power take-off units are connected to transaxle output differential, then torque transfer is enabled, but power losses occur through hypoid gear churning in lubricating fluid
Solution Approach 1:
The patent extracts the hypoid gearset from the continuous rotation path by implementing a disconnect mechanism. When the power take-off unit is disconnected, the ring gear is extracted from the torque transfer path and stops rotating, eliminating the source of churning losses while allowing torque transfer when connected.
Solution Approach 2:
The disconnect system enables periodic engagement and disengagement of the hypoid gearset based on driveline mode requirements. The gearset rotates periodically when torque transfer is needed and remains stationary when not needed, creating a rhythmic on/off pattern that reduces overall energy losses while maintaining necessary power transfer capability.
3Reliability
If rear drive axle hypoid gearset continuously rotates, then driveline functionality is maintained, but churning losses convert energy into heat
Solution Approach 1:
The disconnect system allows the driveline to serve itself by automatically determining when torque transfer is needed and when it is not. Based on driveline mode signals, the system self-regulates the rotation state of hypoid gearsets, stopping them when unnecessary to eliminate churning losses while maintaining functionality when required.
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 significantly reduces energy losses by disconnecting the hypoid gearsets from power sources during non-torque transferring modes, enhancing the overall energy efficiency of the driveline and reducing fuel consumption.
Implementation Method 1
At least one of the first and second power disconnection devices includes a dry friction clutch
Data Source
AI summary
A vehicle drive train for transferring torque to first and second sets of wheels includes a first driveline adapted to transfer torque to the first set of wheels and a first power disconnection device. A second driveline is adapted to transfer torque to the second set of wheels and includes a second power disconnection device. A hypoid gearset is positioned within one of the first driveline and the second driveline in a power path between the first and second power disconnection devices. The hypoid gearset is selectively disconnected from being driven by the first driveline and the second driveline when the first and second power disconnection devices are operated in a disconnected, non-torque transferring, mode. At least one of the first and second disconnection devices includes an active dry friction clutch.