Redundant Electro-Hydraulic Controller for Multi-Mode Transmission Fault Tolerance
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Solution Overview
Problem
Multi-mode automatic transmissions with toroidal traction drives face challenges in maintaining operation during single fault conditions, particularly in continuously variable transmissions where hydraulic circuits control variator torque, leading to potential system failures and loss of functionality.
Innovation Solution
An electro-hydraulic controller with redundancy is introduced, allowing it to respond to single fault failures in flow control valves, ensuring normal operation by altering fluid flow paths and utilizing redundant components to compensate for faults, thereby maintaining transmission functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a hydraulic circuit with flow control valves is used to control variator torque, then the transmission ratio can be continuously adjusted, but the system becomes vulnerable to single fault failures that cause loss of functionality
Solution Approach 1:
The hydraulic circuit is segmented into multiple independent flow paths, each with its own flow control valve. This allows the system to isolate and bypass faulty segments while maintaining operation through alternative paths, resolving the contradiction between continuous adjustment capability and fault tolerance.
Solution Approach 2:
Redundant flow control valves are incorporated into the hydraulic circuit before faults occur. These redundant components remain standby until needed, providing immediate backup capability when a valve fails, thus maintaining reliability without compromising the continuous adjustment capability.
2Reliability
If redundant components are added to the electro-hydraulic controller, then reliability under fault conditions is improved, but device complexity increases
Solution Approach 1:
The redundant flow control valves are merged into the existing electro-hydraulic controller architecture, sharing common mounting structures, fluid passages, and control electronics. This integration approach provides fault tolerance while minimizing the increase in overall device complexity.
Solution Approach 2:
The redundant flow control valves are designed to perform the same function as the primary valves, allowing them to be interchangeably activated based on system needs or fault conditions. This multi-functionality approach ensures reliability without requiring entirely separate backup systems, thereby controlling complexity.
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
The solution enables the transmission to continue operating normally even under single fault conditions, preventing system failure and ensuring continued vehicle operation without loss of functionality, which is not achievable with prior art systems.
Implementation Method 1
The variator torque is controlled by a hydraulic circuit, which includes hydraulic actuators (i.e., pistons) that apply an adjustable force to the rollers
Implementation Method 2
torque is transmitted by the frictional engagement of variator disks and rollers separated by a traction fluid
Implementation Method 3
allowing it to respond to single fault failures in flow control valves, ensuring normal operation by altering fluid flow paths and utilizing redundant components
Data Source
AI summary
A transmission includes an electro-hydraulic controller that includes redundancy in the hydraulic circuit that permits single fault failures to be compensated for by changing the flow path of hydraulic fluid to bypass the single fault failure. The redundancy results in the ability of the transmission to maintain full operation in all modes.