Latching Clutch Control System for Engine Stop-Start Delay
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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 recovery, especially in engine stop/start systems, while also needing to deactivate clutch pressure for reverse gear.
Innovation Solution
A control system with a latching valve and hydraulic pressure storage circuit that traps pressurized fluid within the torque transmitting device, allowing for timely shifting and recovery, and selectively releases fluid to unlatch the clutch when necessary, using accumulators to provide hydraulic fluid pressure when engine power is unavailable.
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 clutch pressure is lost and transmission operation is delayed
Solution Approach 1:
The system performs preliminary action by maintaining clutch pressure in advance during engine operation, storing energy in the spring mechanism before engine shutdown. This allows the clutch to remain engaged immediately upon engine restart without waiting for pressure buildup, thus resolving the contradiction between fuel savings from engine shutdown and transmission operation delay.
2Loss of time
If clutch pressure is maintained during engine shutdown, then transmission recovery time is reduced, but clutch pressure cannot be released for reverse gear operation
Solution Approach 1:
The system implements dynamic control by providing two distinct pathways for clutch pressure: a retention pathway that maintains pressure during normal operation and engine shutdown, and a release pathway that allows rapid pressure discharge when reverse gear is selected. This dynamic switching capability resolves the contradiction between quick recovery and reverse gear adaptability.
Solution Approach 2:
The patent introduces an intermediary release valve mechanism that mediates between the pressure retention system and the clutch cavity. This intermediary component allows controlled pressure release for reverse gear operation without affecting the overall pressure maintenance system, thus enabling both quick recovery and reverse gear capability.
3Speed
If a latching valve is added to maintain clutch pressure, then transmission operation speed is improved, but device complexity increases
Solution Approach 1:
The latching valve is designed as a self-service component that automatically latches and unlatches based on system conditions without requiring complex external control mechanisms. The valve uses the existing hydraulic pressure and spring forces to operate, minimizing additional control system complexity while achieving improved transmission operation speed.
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 quick and efficient transmission operation upon engine restart, reduces delay in establishing pressure, and allows for seamless gear changes, including reverse, by maintaining hydraulic fluid pressure within the clutch cavity even when the engine is off.
Implementation Method 1
A latching valve connects the clutch feed channel to the torque transmitting device. The latching valve is configured to selectively trap pressurized hydraulic fluid within the torque transmitting device.
Implementation Method 2
A hydraulic pressure storage circuit is configured to selectively provide pressurized hydraulic fluid to the latching valve to unlatch the latching valve.
Implementation Method 3
One or more release valves are opened to release fluid from an accumulator to exert fluid pressure on the latching valve. Upon exerting fluid pressure on the latching valve, the latching valve opens to allow fluid to flow from the clutch cavity
Data Source
AI summary
A clutch latching system is provided for latching and draining a torque transmitting mechanism. The latching clutch control system may include a latching valve, a release valve, and an accumulator. The clutch latching system may include a clutch feed channel configured to provide hydraulic fluid from a pressurized source to a torque transmitting device when the torque transmitting device is engaged and the engine is running. A latching valve connects the clutch feed channel to the torque transmitting device. The latching valve is configured to selectively trap pressurized hydraulic fluid within the torque transmitting device. A hydraulic pressure storage circuit configured to selectively provide pressurized hydraulic fluid to the latching valve to unlatch the latching valve. A multiple speed transmission is also provided.