Hydraulic Control System for Automatic Transmission Default Mode
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Solution Overview
Problem
Conventional hydraulic control systems for automatic transmissions fail to provide reliable forward and reverse driving states during default conditions, such as electronic control failures or hardware malfunctions, leading to unintended shifts into neutral.
Innovation Solution
A hydraulic control system with a pressure regulation subsystem, manual valve assembly, default disable valve assembly, and clutch regulation valve assemblies that allow for manual selection of gear states, enabling two forward gears and a reverse gear through a network of solenoids, valves, and clutch regulation, even in the absence of electronic control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional hydraulic control system is used, then the transmission can operate under normal electronic control, but it fails to provide reliable forward and reverse driving states during default conditions
Solution Approach 1:
The hydraulic control system is segmented into multiple independent valve assemblies: a manual valve assembly with spool for directional control, a default disable valve assembly with spool for enabling/disabling default mode, and a default select valve assembly with spool for selecting between forward and reverse gears. Each valve assembly operates independently through dedicated hydraulic circuits, allowing the system to maintain forward and reverse functionality during default conditions while keeping the overall system manageable through modular design.
2Ease of operation
If electronic control is used, then gear shifting is automated and convenient, but the system becomes vulnerable to electronic failures and hardware malfunctions
Solution Approach 1:
The system introduces a default disable valve assembly as an intermediary between the electronic control system and the hydraulic clutch control. This valve assembly includes a spool that can be actuated by electronic signals under normal operation, but also has a default position that enables manual gear selection through the manual valve assembly when electronic control fails. The intermediary valve allows seamless transition between electronic and manual control modes, ensuring reliability during electronic failures.
3Device complexity
If the transmission shifts to neutral during default conditions, then the hydraulic system is simplified, but the vehicle loses driving capability
Solution Approach 1:
The manual valve assembly is pre-configured with spool positions corresponding to different gear states (reverse, neutral, first forward gear, second forward gear). The default select valve assembly is pre-configured to direct hydraulic fluid to appropriate clutch circuits based on the manual valve position. This preliminary configuration of hydraulic pathways ensures that when electronic control fails, the system can immediately provide forward and reverse driving capability without shifting to neutral, maintaining vehicle productivity during default conditions.
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 reliable operation of automatic transmissions during default conditions by allowing manual selection of gear states, ensuring continued functionality and safety during electronic failures or hardware malfunctions.
Implementation Method 1
a default disable solenoid in direct fluid communication with the default disable valve assembly
Data Source
AI summary
A hydraulic control system for a motor vehicle transmission includes a pressure regulation subsystem in fluid communication with a pump for providing pressurized hydraulic fluid. A manual valve assembly is in direct fluid communication with the pressure regulation subsystem, and is moveable by an operator of the motor vehicle between at least park, neutral, drive, and reverse positions. A default disable valve assembly is in direct fluid communication with the manual valve assembly, a default disable solenoid, and a default select valve assembly. The manual valve assembly is in direct fluid communication with the default disable valve assembly which is in direct fluid communication with the default disable solenoid and the default select valve assembly. The default disable solenoid enables the default disable valve assembly to enable three default modes of operation and the default select valve assembly selects between two of the three default modes of operation.