Selectable One-Way Clutch for Hybrid Transmission Actuation
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Solution Overview
Problem
Conventional clutch packs in hybrid gasoline/electric transmissions require high hydraulic pump pressure for quick actuation, leading to energy losses in the hydraulic circuit and spin losses at the clutch plate interface, which affects fuel efficiency and emission reduction.
Innovation Solution
A controllable three-mode selectable one-way clutch with a motor controller for speed synchronization and a transmission controller for mode selection, utilizing an outer and inner race with sliding selector plates and actuators to manage clutch operational modes, including freewheeling, torque holding in one direction, and torque holding in both directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional clutch packs are used for gear shifting in hybrid transmissions, then gear shifting can be achieved, but high hydraulic pump pressure is required leading to energy losses in the hydraulic circuit and spin losses at the clutch plate interface
Solution Approach 1:
The clutch system transitions from a static conventional clutch pack to a dynamic selectable one-way clutch mechanism that can change its operational characteristics. The clutch allows one-way torque transmission while permitting reverse rotation, enabling the system to adapt between locked and freewheeling states based on operating conditions, thereby reducing energy losses during gear shifting operations.
Solution Approach 2:
The invention changes the fundamental parameter of clutch torque transmission from bidirectional (conventional) to unidirectional (one-way). This parameter change allows the clutch to freewheel in the reverse direction, eliminating the need for high hydraulic pressure during certain operations and reducing both hydraulic circuit losses and spin losses at the clutch plate interface.
2Speed
If high hydraulic pump pressure is applied to quickly actuate the clutch-apply mechanism, then clutch engagement speed is improved, but energy losses in the hydraulic circuit increase
Solution Approach 1:
The selectable one-way clutch enables periodic alternation between locked and freewheeling states. During gear shifting, the clutch can quickly transition to a freewheeling state, allowing rapid operational changes without requiring sustained high hydraulic pressure, thus reducing energy losses while maintaining fast response capability.
Solution Approach 2:
The invention converts what would traditionally be a harmful condition (clutch disengagement or reverse rotation) into a beneficial freewheeling state. By allowing the clutch to freewheel in the reverse direction, the system eliminates the need for high pressure actuation during these phases, transforming potential energy losses into energy-saving opportunities.
Data Source
AI summary
A controllable selectable one-way clutch is provided for use within a hybrid transmission. The clutch comprises an outer and inner race, and a first and second selector plate. A transmission motor controller synchronizes the speeds of the races to facilitate application and release of the clutch, and a transmission controller communicates a signal to the clutch for re-positioning of the plates to apply and release the clutch. The clutch has three operational modes, including freewheeling and holding torque in one direction or both directions. A method is also provided for applying a selectable one-way clutch in a vehicle having a hybrid transmission with a motor controller and a transmission controller, including synchronizing the clutch speed using the motor controller, detecting the direction of the race speed difference, communicating the race speed difference to the transmission controller, and selecting between the clutch operational modes in response to the detected speed difference.