Latching Clutch Control System for Automatic Transmission
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Automatic transmissions face challenges in maintaining clutch pressure when the engine is shut off, leading to delayed transmission operation upon restart and requiring quick shift timing and system recovery, while also needing to deactivate clutch pressure for reverse gear engagement.
Innovation Solution
A latching system using one-way valves and bypass valves to retain and release hydraulic fluid in torque-transmitting mechanisms, allowing clutch pressure to be maintained or released as needed, even when engine pressure is zero, by trapping fluid within the clutch cavity and allowing drainage when required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine is shut off to improve fuel economy, then fuel consumption is reduced, but hydraulic fluid drains from the clutch passages into the transmission sump under gravity, causing delayed transmission operation upon restart
Solution Approach 1:
The one-way valve is pre-installed in the clutch feed passage to automatically prevent fluid drainage when the engine shuts off. This preliminary structural arrangement ensures that upon engine restart, the clutch pressure is already maintained and ready for immediate operation, eliminating the need for time-consuming pressure rebuild
Solution Approach 2:
The one-way valve acts as an intermediary component between the clutch feed passage and the transmission sump. It selectively blocks the gravitational drainage of hydraulic fluid while allowing normal pressure-driven flow during operation, thus mediating between fuel economy requirements and transmission responsiveness
2Speed
If clutch pressure is maintained during engine shutdown, then quick shift timing and system recovery are achieved, but clutch pressure cannot be released when reverse gear engagement is required
Solution Approach 1:
The system transitions from a static pressure retention approach to a dynamic controlled release approach. The bypass valve is dynamically actuated by the control module based on gear selection signals, allowing the clutch pressure to be released on demand for reverse gear engagement while maintaining pressure for quick recovery in forward gears
Solution Approach 2:
The control module receives feedback about the desired gear selection and automatically actuates the bypass valve accordingly. When reverse gear is selected, the control module triggers the bypass valve to open and release clutch pressure, ensuring the transmission is adaptable to different operational requirements
3Reliability
If a one-way valve is installed to prevent fluid drainage, then clutch pressure is retained during engine shutdown, but fluid cannot be released from the clutch cavity when needed
Solution Approach 1:
The fluid control function is segmented into two independent pathways: a one-way valve for automatic pressure retention during shutdown, and a bypass valve for controlled pressure release when needed. This segmentation allows each valve to specialize in its function without interfering with the other
Solution Approach 2:
The bypass valve serves as a mediator that overrides the one-way valve's retention function when reverse gear engagement is required. The control module actuates the bypass valve to create a controlled drainage path, temporarily suspending the one-way valve's blocking action to allow fluid release
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
Enables timely shifting and recovery of the transmission, prevents fluid drainage during engine shutdown, and allows for smooth gear changes, including reverse, by effectively managing clutch pressure through the latching and unlatching of hydraulic fluid within the torque-transmitting devices.
Implementation Method 1
a one-way valve, such as a ball check-valve, is located between the torque transmitting mechanism and the control fluid that feeds the torque transmitting mechanism, allowing fluid to flow into the clutch cavity of the torque transmitting mechanism but not to return therefrom
Implementation Method 2
A bypass valve is placed in parallel with the one-way valve to allow fluid to flow from the clutch cavity when it is desired to release clutch pressure
Implementation Method 3
The inlet portion is configured to provide hydraulic fluid from a pressurized source to the clutch portion. The clutch portion is configured to provide hydraulic fluid to a torque transmitting device
Data Source
AI summary
A system is provided for latching and draining a torque transmitting device. The system may include a clutch feed channel having an inlet portion and a clutch portion. The inlet portion is configured to provide hydraulic fluid from a pressurized source to the clutch portion. The clutch portion is configured to provide hydraulic fluid to a torque transmitting device. An inlet valve connects the inlet portion of the clutch feed channel to the clutch portion of the clutch feed channel. The inlet valve is configured to open to allow the hydraulic fluid to flow from the inlet portion to the clutch portion when the torque transmitting device is engaged. The inlet valve is configured to close and to trap hydraulic fluid within the torque transmitting device when the torque transmitting device is not actively pressurized. A multispeed transmission is also provided.