Automatic Transmission Range Control via Proactive Valve Verification
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Solution Overview
Problem
Conventional automatic transmission shift-by-wire systems face issues with undesirable failure modes and inadequate diagnostics, leading to potential hazardous conditions for the vehicle and driver, especially due to undetected component failures during range changes.
Innovation Solution
A method for controlling internal electronic range selection in automatic transmissions that includes verifying component performance, generating proactive commands, and modifying them to ensure safe states during range changes, with four layers of proactive safety software to monitor and respond to unexpected events and single element failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional shift-by-wire systems are used, then mechanical complexity is reduced, but system reliability deteriorates due to undetected component failures and inadequate diagnostics
Solution Approach 1:
The patent applies preliminary action by performing proactive safety checks and verifying component performance before allowing range changes to occur. The system checks the state of mode valves, park servo, and other critical components in advance, and only permits range changes when all components are confirmed to be in expected states, thereby preventing failures before they can cause hazardous conditions
Solution Approach 2:
The patent implements feedback through continuous monitoring of system components during range change events. The controller receives feedback signals from position switches and sensors that indicate the actual state of mode valves and park servo, and uses this feedback to verify whether components have moved to expected positions, allowing the system to detect and respond to unexpected events in real-time
2Reliability
If traditional mechanical range shift mechanisms are used, then system reliability is maintained, but device complexity and manufacturing cost increase due to numerous mechanical components
Solution Approach 1:
The patent applies mechanics substitution by replacing traditional mechanical range shift mechanisms with an electronic control system. Instead of using mechanical linkages, cables, and levers to shift ranges, the system uses electronic commands from the controller to actuate mode valves and park servo, thereby eliminating numerous mechanical components while maintaining reliable range changing functionality through electronic monitoring and control
3Device complexity
If conventional diagnostic monitoring is used, then system simplicity is maintained, but safety deteriorates due to inability to detect unexpected events during range changes
Solution Approach 1:
The patent applies preliminary action in diagnostics by verifying the expected performance of multiple monitored system components before allowing a range change event to proceed. The controller checks that mode valves and park servo are in correct positions and will operate as expected, preventing range changes when component failures are detected in advance
Solution Approach 2:
The patent implements enhanced feedback monitoring during range change events by continuously checking the actual positions of mode valves and park servo against expected positions. When unexpected events are detected through feedback from position switches and sensors, the system can immediately identify the discrepancy and take corrective action, providing real-time safety monitoring that conventional diagnostics cannot achieve
Data Source
AI summary
A method for controlling internal electronic range selection for an automatic transmission includes: confirming if a range change command has been ordered from a current transmission operating state; verifying expected performance from at least first and second mode valves and a park servo are present in the current transmission operating state prior to allowing a range change event; during the range change event: generating proactive commands including ordering a reduction in a hydraulic system pressure; and identifying if an unexpected event is detected; and following completion of the range change event confirming expected performance is obtained from at least the first and second mode valves and the park servo to achieve a driver intended state.