Automatic Transmission Control for Cryogenic Engine Stalling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Automatic transmissions with torque converters featuring a separate chamber multi-plate clutch structure experience excessive drag torque at cryogenic temperatures, leading to engine stalling during initial gear shifting due to high viscosity transmission oil and poor oil flow, causing the turbine to fail in smoothly disconnecting from the engine.
Innovation Solution
A method for controlling the automatic transmission that reduces engine rotation and line pressure at the start of shifting, increases fluid pressure to the reverse clutch, and adjusts turbine rotation to zero, thereby minimizing drag and preventing engine stalling by gradually increasing engine rotation and line pressure for smooth gear shifting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a torque converter with separate chamber multi-plate clutch structure is used in automatic transmission, then gear shifting operation is improved, but excessive drag torque occurs at cryogenic temperatures causing engine stalling
Solution Approach 1:
The control method applies preliminary action by reducing engine rotation speed and line pressure before the gear shifting operation commences. This preparatory reduction in rotational speed and pressure prevents excessive drag torque from developing during the shifting process, thereby avoiding engine stalling while maintaining effective gear shifting operation.
Solution Approach 2:
The invention applies dynamics by dynamically adjusting engine rotation speed and line pressure based on operating conditions. During initial gear shifting at cryogenic temperatures, the system dynamically reduces these parameters to minimize drag torque, then gradually increases them as the shifting progresses, ensuring reliable operation without engine stalling.
2Reliability
If engine rotation speed is reduced to minimize drag torque, then engine stalling is prevented, but gear shifting efficiency may be compromised
Solution Approach 1:
The control method applies periodic action by implementing a multi-stage sequence: first reducing engine rotation speed and line pressure to prevent stalling, then gradually increasing them as the shifting progresses. This periodic variation in operational parameters ensures both engine stalling prevention and maintained gear shifting efficiency through controlled progression through different pressure and speed phases.
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
This method enhances the startability of the engine by reducing drag torque and preventing engine stalling during gear shifts at cryogenic temperatures, improving fuel efficiency and reducing the risk of engine shutdown.
Implementation Method 1
a torque converter changes a rotational power of an engine
Implementation Method 2
a solenoid valve is controlled by a control signal applied from a transmission control unit (TCU) according to a driving state of the vehicle so that a hydraulic circuit which operates a friction element is formed
Data Source
AI summary
A method for controlling an automatic transmission includes reducing, by a controller, a number of rotation of the engine connected to the automatic transmission to the first number of rotation when a shifting of the automatic transmission is started. The method further includes reducing, by the controller, a line pressure that is a hydraulic pressure of a flow line that operates the automatic transmission when the shifting of the automatic transmission is started.