Automatic Transmission Alternate Forward Start Gear Downshift Control
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Solution Overview
Problem
Off-road machines with automatic transmissions equipped with an alternate start gear and first gear lock out feature lack the capability to automatically downshift to a lower gear when environmental and machine conditions necessitate more power, leading to inadequate performance and inefficient operation.
Innovation Solution
An electronic control system with sensors and a transmission electronic controller that detects engine speed, transmission speed, oil temperature, vehicle payload, and terrain grade, and initiates a downshift from the alternate forward start gear to the lower forward start gear when conditions warrant, ensuring adequate power delivery and preventing performance inhibition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the transmission operates in alternate forward start gear (second gear or higher) to eliminate shifting time and improve acceleration, then machine acceleration is improved, but power delivery becomes inadequate when environmental and machine conditions require more power
Solution Approach 1:
The transmission system dynamically switches between alternate forward start gear and lower forward start gear based on real-time sensor inputs. The electronic controller continuously monitors engine speed, transmission speed, oil temperature, vehicle payload, and terrain grade to determine the optimal gear selection, making the system adaptive to changing operating conditions
Solution Approach 2:
The system changes the gear ratio parameter based on detected operating conditions. When sensors indicate that environmental and machine conditions require more power, the electronic controller initiates a downshift from the alternate forward start gear to the lower forward start gear, effectively changing the transmission ratio to provide adequate power delivery
2Productivity
If the lower forward start gear lock out feature prevents starting in lower gear during normal drive mode to maintain efficient operation, then operational efficiency is improved, but the machine cannot access lower gears when performance is needed
Solution Approach 1:
The gear lockout feature transitions from a static restriction to a dynamic control mechanism. The electronic controller evaluates sensor data in real-time and dynamically adjusts gear availability, disabling the lockout only when conditions warrant additional power, thus maintaining efficiency during normal operation while providing adaptability when needed
Solution Approach 2:
The system uses sensor feedback (engine speed, transmission speed, oil temperature, vehicle payload, percent grade) to continuously monitor operating conditions and determine when the lockout should be overridden. This feedback mechanism allows the system to maintain efficiency while adapting to conditions that require more power
3Power
If the transmission automatically downshifts to lower gear when conditions warrant more power, then power delivery is improved, but system complexity increases due to additional sensors and control logic
Solution Approach 1:
The electronic controller performs multiple functions: it monitors multiple sensor inputs, determines optimal gear selection, manages the lockout feature, and initiates downshifts. By consolidating these functions in a single controller, the system achieves the needed complexity while avoiding the need for separate control systems for each function
Solution Approach 2:
The transmission system automatically monitors its own operating conditions through sensors and self-regulates gear selection based on detected conditions. The electronic controller autonomously determines when downshifting is necessary and executes the gear change without operator intervention, making the system self-managing
Data Source
AI summary
An electronic control system for an automatic transmission having an alternate forward start gear, a lower forward start gear and a lower forward start gear lock our feature, in which the electronic control system can sense from various conditions when more power to the drive train is needed and cause the automatic transmission to automatically downshift to the lower forward start gear.