Marine Transmission Shift Timing for Redline RPM Protection
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Solution Overview
Problem
Existing marine propulsion systems with multi-speed transmissions face challenges in efficiently shifting gears based on engine speed and load, leading to suboptimal performance and fuel efficiency.
Innovation Solution
A method and system for shifting a multi-speed transmission in a marine propulsion device, which involves measuring the powerhead RPM, comparing it to predefined thresholds, and determining a shift RPM based on the transition time and redline RPM of the powerhead, to ensure shifting completes before reaching the redline RPM.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If gear shifting is controlled based on engine speed and load, then transmission performance is improved, but the risk of exceeding redline RPM increases
Solution Approach 1:
The system calculates the required shift time based on the transition curve before initiating the gear shift. By determining the shift completion time in advance and working backward to identify the optimal shift initiation point, the system ensures the shift completes exactly at the target RPM without exceeding redline, thus preventing harmful effects while maintaining performance
Solution Approach 2:
The system continuously monitors engine RPM and compares it against the transition curve during the shifting process. This real-time feedback allows the control system to verify that the shift is proceeding as predicted and to make adjustments if necessary, ensuring the shift completes at the correct moment and preventing redline exceedance
2Reliability
If gear shifting is delayed to prevent redline exceedance, then engine protection is improved, but acceleration performance deteriorates
Solution Approach 1:
The system uses the pre-calculated transition curve to determine the exact moment when gear shifting should be initiated to complete the shift at the optimal point before redline. This advance planning allows the system to shift at the precise optimal moment rather than delaying conservatively, thus maintaining acceleration performance while protecting the engine
Solution Approach 2:
The transition curve is dynamically adjusted based on current engine operating conditions, allowing the shift timing to be optimized for each specific situation. This dynamic approach enables the system to extract maximum performance from each gear shift while still ensuring engine protection, rather than using fixed conservative timing
3Stability of the object's composition
If multiple marine propulsion devices shift simultaneously, then system coordination is improved, but the risk of synchronized redline exceedance increases
Solution Approach 1:
The control system continuously monitors RPM across all marine propulsion devices and uses feedback from the transition curve to coordinate shifting timing. This ensures that even when multiple devices shift simultaneously for coordinated operation, each device's shift is precisely timed to complete at its own optimal point, preventing synchronized redline exceedance
Solution Approach 2:
Before initiating coordinated shifts across multiple devices, the system pre-calculates the shift timing for each device based on its transition curve and current operating conditions. This advance planning allows simultaneous shifting to be coordinated in a way that maintains system stability while preventing redline issues
Data Source
AI summary
A method for shifting a marine propulsion device transmission between first and second gears transmitting torque from a powerhead with a redline RPM. The transmission has a transition time for completing a shift. The method includes measuring an RPM of the powerhead, comparing the RPM to a first threshold, and starting a timer when the RPM exceeds the first threshold. The method includes measuring the RPM of the powerhead after the first threshold is exceeded, comparing the RPM to a second threshold, stopping the timer when the RPM exceeds the second threshold, determining an elapsed time between starting and stopping the timer, and determining a shift RPM based on the determined elapsed time, the redline RPM, and the transition time of the transmission. The method includes controlling the transmission to shift when the RPM measured for the powerhead reaches the shift RPM such that shifting completes before the redline RPM.