Selectable One-Way Clutch for Electric Vehicle Two-Speed Drive
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current electrical vehicle two-clutch systems are not selectable and suffer from inefficiency due to friction-induced drag during free-wheeling, limiting the operating efficiency of two-speed drive systems.
Innovation Solution
A two-speed drive unit with a planetary gear set transmission and a selectable one-way clutch (SOWC) system, where a motor generator unit supplies motive force through a first and second stage gear, and a second torque transmitting device is selectively engaged to achieve two drive speed ranges, with a controller managing the SOWC's locking and unlocking members for efficient gear shifting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a friction clutch is used in a two-clutch system for free-wheeling, then the system can achieve automatic braking in one direction and free-wheeling in the opposite direction, but friction-induced drag during free-wheeling creates inefficiency in the drive system
Solution Approach 1:
The patent extracts the friction element from the torque transmitting path during free-wheeling operations. The selectable one-way clutch mechanism allows the system to disengage the friction clutch from the power flow path when free-wheeling is required, eliminating friction-induced drag while maintaining automatic braking capability when needed.
Solution Approach 2:
The patent implements dynamic selection of clutch engagement states through the selectable one-way clutch (SOWC) mechanism. The controller dynamically switches between locked and unlocked states of the SOWC to selectively engage or disengage the friction clutch based on operating conditions, optimizing both braking performance and efficiency.
2Productivity
If a two-clutch system with friction clutch is used for two-speed transmission, then shifting between speeds is achieved, but the system is not selectable and always automatically brakes one direction while free-wheeling in the opposite direction
Solution Approach 1:
The patent transforms the static two-clutch system into a dynamic, selectable system through the SOWC mechanism. The controller can dynamically select between different operational modes (locked or unlocked states) based on vehicle conditions, enabling adaptable operation rather than fixed automatic braking/free-wheeling behavior.
Solution Approach 2:
The selectable one-way clutch mechanism provides multi-functionality by enabling the system to perform multiple operations: automatic braking, free-wheeling, and selectable engagement/disengagement modes. This universal mechanism allows the same hardware to adapt to different operational requirements without requiring separate systems.
3Manufacturing precision
If a selectable one-way clutch is electrically actuated with multiple locking and unlocking members, then precise control of gear ratios is achieved, but the device complexity increases
Solution Approach 1:
The patent replaces complex mechanical actuation systems with electrical actuation through the electrically actuated SOWC mechanism. Electrical motors or actuators control the locking and unlocking members, providing precise control with simpler actuation infrastructure compared to purely mechanical systems.
Solution Approach 2:
The controller serves as an intermediary between the electrical actuation system and the mechanical locking/unlocking members. It coordinates the operation of multiple members systematically, managing the complexity through intelligent control logic that sequences engagements and disengagements to achieve precise gear ratio control.
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 solution enables improved shift quality and energy recapture through regenerative braking, maintaining high efficiency by selecting the appropriate gear ratio and reducing friction-induced inefficiencies, thus enhancing the overall performance of the two-speed drive system.
Implementation Method 1
The SOWC is electrically actuated. A controller signals operation of multiple locking and unlocking members of the SOWC.
Implementation Method 2
A second torque transmitting device is provided between the first element and the second element selectively frictionally engaged to couple the first element to the second element. the second torque transmitting device defines a friction clutch.
Data Source
AI summary
A two-speed drive unit of an electric vehicle includes a planetary gear set transmission having multiple elements including a first element, a second element and a third element. A motor generator unit supplies a motive force to the planetary gear set transmission. A first stage gear transfers the motive force to the planetary gear set transmission from the motor generator unit. A second stage gear is connected through the second element to a final drive. A first torque transmitting device defining a selectable one-way clutch (SOWC) is connected to the third element.