Marine Propulsion Starter-Generator for Hydrolock Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Marine engines face hydrolock issues when suddenly shifted into reverse gear while moving forward at high speeds, causing damage due to water ingestion and insufficient torque response from the engine combustion strategy.
Innovation Solution
A starter-generator motor is used to exert torque on the driveshaft in both positive and negative modes to prevent engine stalling and facilitate smooth gear shifts, including applying negative torque to slow down the engine RPM and switch to positive torque to assist in initiating reverse rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the engine is suddenly shifted into reverse gear while moving forward at high speed, then the gear shift is achieved, but water ingestion occurs causing hydrolock and engine damage
Solution Approach 1:
The control system detects the gear shift command and proactively reduces engine RPM to a safe threshold before the reverse gear is fully engaged. This preliminary action prevents water from being forced into the cylinders during the transition, eliminating the hydrolock condition while still achieving swift gear shifting.
2Power
If the engine combustion strategy is used to respond to reverse gear engagement, then the engine can provide torque, but the response is insufficient and slow
Solution Approach 1:
The control system acts as an intermediary between the gear shift command and the engine combustion system. It mediates by first reducing RPM to a safe level, then coordinating the reverse gear engagement, and finally managing the combustion response. This intermediary control ensures both safe operation and optimal torque delivery without the delays caused by water ingestion or uncoordinated system responses.
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
Prevents hydrolock by maintaining propeller rotation direction and reducing engine RPM quickly to enable swift gear shifts, thereby preventing engine stalling and ensuring safe and efficient reverse gear engagement.
Implementation Method 1
A marine propulsion device includes an internal combustion engine driving a driveshaft into rotation and a starter-generator motor in a torque transmitting relationship with the driveshaft
Data Source
AI summary
A marine propulsion device includes an internal combustion engine driving a driveshaft into rotation and a starter-generator motor in a torque transmitting relationship with the driveshaft. The starter-generator motor is alternately operable in a positive torque mode where it is powered by a battery to exert a positive torque on the driveshaft, and in a negative torque mode where it exerts a negative torque on the driveshaft and generates a charge to the battery. A control module is configured to receive an engine RPM, determine an engine RPM drop rate, and determine that the engine RPM drop rate exceeds a threshold drop rate. The starter-generator motor is then operated in a positive torque mode based on the engine RPM drop rate when the engine RPM drop rate exceeds the threshold drop rate.