Toroidal Traction Drive Transmission Control Valves
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Solution Overview
Problem
Toroidal traction drive automatic transmissions face challenges in multiplexing gear engagement control and providing fault protection, as existing systems lack efficient mechanisms to manage gear engagement and detect fault conditions effectively.
Innovation Solution
The system employs multiple friction engagement devices, a trim system, and control valves to selectively route engagement and disengagement pressures, allowing for multiplexing of gear engagement control and fault protection by configuring the valves to manage pressure distribution across different gear ratios and fault conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple separate control valves are used for each friction engagement device, then reliability and fault protection are improved, but device complexity increases
Solution Approach 1:
The first control valve is designed to perform multiple functions by selectively routing fluid pressure to multiple friction engagement devices (first and second friction engagement devices) through a single valve body with multiple outlets. This multi-functional design reduces the total number of valves needed while maintaining the ability to independently control each friction engagement device, thereby reducing system complexity without compromising reliability or fault protection capabilities
2Device complexity
If a single control valve is used to multiplex gear engagement control, then device complexity is reduced, but measurement precision and fault detection capability deteriorate
Solution Approach 1:
The control system is segmented into multiple independent control valves (first control valve, second control valve, third control valve) that can be selectively activated based on fault conditions. Each valve can independently monitor and control specific friction engagement devices, allowing for precise fault detection in individual components while using a shared first control valve for common functions. This segmented approach enables localized fault detection without requiring a completely separate control system for each device
3Reliability
If separate fluid passageways are used for each friction engagement device, then reliability and fault isolation are improved, but device complexity and fluid system complexity increase
Solution Approach 1:
The fluid delivery system is merged by having the first control valve share a common inlet and control mechanism for multiple friction engagement devices. The valve body integrates multiple outlets that can independently direct fluid to different devices, combining the benefits of separate fluid paths (for fault isolation) with a unified control structure (reducing overall system complexity). This merging approach maintains reliability through independent fluid paths while simplifying the control architecture
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 solution enables effective multiplexing of gear engagement control and fault protection, ensuring smooth transitions between operating modes and maintaining transmission functionality even under fault conditions by selectively engaging appropriate gear ratios.
Implementation Method 1
a trim system configured to selectively supply engagement and disengagement pressures to at least one fluid passageway
Implementation Method 2
a first control valve fluidly coupled directly to the at least one fluid passageway and directly to each of the at least two friction engagement devices. The first control valve may be configured to selectively route the engagement and disengagement pressures through the first control valve directly to the at least two friction devices
Data Source
AI summary
An apparatus for multiplexing gear engagement control in an automatic transmission is provided. At least two friction engagement devices are configured to selectively engage and disengage a different gear ratio of the transmission. A trim system is configured to selectively supply engagement and disengagement pressures to at least one fluid passageway. A first control valve is fluidly coupled directly to the at least one fluid passageway and directly to each of the at least two friction engagement devices. The first control valve is configured to selectively route the engagement and disengagement pressures through the first control valve directly to the at least two friction devices.