Selectable One-Way Clutch for Automatic Transmission
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In vehicle transmissions with one-way clutches, the disengaged multi-plate clutches experience drag, leading to spin losses and decreased fuel economy, particularly in forward gears where the low and reverse clutch is disengaged, resulting in increased relative speed between input and output components.
Innovation Solution
A frictionless engagement selectable one-way clutch (SOWC) with a controllable selection mechanism allows for operation in two modes: disengaged mode for torque transmission in one direction and freewheeling in the reverse direction, and engaged mode for torque transmission in both directions, reducing part complexity, weight, and spin losses by eliminating the need for additional components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional one-way clutch is used in the transmission, then torque can be transmitted in one direction with freewheeling capability, but additional components are required to achieve engine braking, increasing device complexity
Solution Approach 1:
The selectable one-way clutch is designed to perform multiple functions: it can operate as a traditional one-way clutch for torque transmission and freewheeling, or be selectively engaged to enable engine braking. This multi-functionality eliminates the need for separate additional clutch components, reducing device complexity while maintaining adaptability for different operating modes
Solution Approach 2:
The clutch system incorporates a selectable engagement mechanism that dynamically changes the clutch state based on operating conditions. The clutch can be selectively engaged or disengaged through a control system that monitors transmission gear state and driving conditions, allowing the system to adapt between torque transmission mode and engine braking mode without requiring separate fixed components
2Loss of energy
If the low and reverse clutch is disengaged in forward gears to allow one-way clutch freewheeling, then fuel economy improves through reduced drag, but spin losses increase due to relative motion between clutch components
Solution Approach 1:
The control system applies partial engagement of the selectable one-way clutch in certain forward gears where traditional one-way clutches would freewheel. Instead of complete disengagement, the clutch is selectively engaged just enough to reduce spin losses between components while maintaining sufficient torque transmission capability, achieving a balance that reduces energy loss without excessive drag
Solution Approach 2:
The system dynamically changes the engagement parameter of the selectable one-way clutch based on operating conditions. By adjusting the clutch engagement state between fully disengaged and fully engaged, the control system optimizes the balance between minimizing drag for fuel economy and reducing spin losses, with the ability to select intermediate engagement levels to address both concerns
3Adaptability or versatility
If a selectable one-way clutch is engaged to enable engine braking, then torque transmission in both directions is achieved, but locked conditions may occur that prevent disengagement during upshifts
Solution Approach 1:
The control system continuously monitors the engagement state and operating parameters of the selectable one-way clutch. When an upshift is commanded, the feedback mechanism detects the engagement state and automatically controls the disengagement timing and sequence, ensuring the clutch is properly disengaged before the upshift occurs to prevent locked conditions, thereby maintaining ease of operation
Solution Approach 2:
The control system performs preliminary disengagement of the selectable one-way clutch before executing the upshift command. By anticipating the upshift requirement and proactively disengaging the clutch in advance, the system prevents locked conditions from occurring, ensuring smooth operation and ease of clutch management during gear transitions
Data Source
AI summary
A method for controlling a powertrain includes monitoring engagement status of said selectable one-way clutch, monitoring an upshift command, monitoring a speed of an engine to torque converter shaft, monitoring a speed of a torque converter to transmission shaft, when the monitoring detects engagement of the selectable one-way clutch and the upshift command, then determining a relative rotational speed of the torque converter based upon the speed of said engine to torque converter shaft and the speed of said torque converter to transmission shaft. A locked selectable one-way clutch condition is diagnosed based upon the relative rotational speed. A torque increase is commanded from the engine based upon the locked selectable one-way clutch condition. And disengagement of the selectable one-way clutch is commanded.