Jet Watercraft Reverse Gate Stabilization Control
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Solution Overview
Problem
In jet propelled watercraft, the reverse gate becomes unstable when the engine stops, requiring the engine to be restarted to move it to the forward drive position for maintenance, which can lead to overheating due to lack of cooling water.
Innovation Solution
A controller is programmed to move the reverse gate to the forward drive position upon engine stoppage and maintain it there, eliminating the need to restart the engine for maintenance and stabilizing the gate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the reverse gate is moved to the neutral position when the engine stops, then the shift actuator can be simple in structure, but the reverse gate becomes unstable after engine stoppage
Solution Approach 1:
The controller moves the reverse gate to the forward drive position in advance when engine stoppage is detected, before maintenance operations begin. This preliminary action ensures the gate is stabilized at a known position (forward drive position with mechanical stopper engagement) before the engine is stopped for maintenance, eliminating the instability problem at the neutral position.
2Ease of operation
If the engine is restarted to move the reverse gate to the forward drive position for water-washing, then the reverse gate can be positioned correctly, but the engine may overheat due to lack of cooling water
Solution Approach 1:
The reverse gate is moved to the forward drive position in advance while the engine is still running, utilizing the engine's operational state to complete the positioning action. This allows the gate to be properly positioned for water-washing maintenance without requiring engine restart, thereby avoiding overheating while still achieving correct gate positioning for maintenance access.
3Device complexity
If the reverse gate is kept at the neutral position, then the shift actuator can be simple, but the jet pump cannot be accessed for water-washing when the engine is stopped
Solution Approach 1:
The controller automatically moves the reverse gate to the forward drive position before engine stoppage is finalized, ensuring the gate is in the correct position that provides access to the jet pump for water-washing maintenance. This preliminary positioning action maintains simple shift actuator structure while enabling maintenance accessibility without requiring complex additional mechanisms.
Data Source
AI summary
A jet propelled watercraft includes a prime mover, a jet pump driven by the prime mover and jetting water from a jet port, a reverse gate changing a direction of the jet flow jetted from the jet pump, a shift actuator capable of moving a position of the reverse gate to a plurality of shift positions including a forward drive position, at which the direction of the jet flow is toward the rear of the body, a reverse drive position, at which the direction of the jet flow is toward the front of the body, and an intermediate position in between these positions, and a controller configured or programmed to execute a stoppage shift control of controlling the shift actuator to move the reverse gate to the forward drive position when stoppage of the prime mover is detected.