Outboard Motor Reverse Rotation Control Device
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Solution Overview
Problem
Existing boat propulsion systems face challenges in preventing water from entering the internal combustion engine due to reverse crankshaft rotation, leading to increased manufacturing costs and complex maintenance requirements, especially when shifting gears from forward to reverse and vice versa.
Innovation Solution
A control device with a reverse rotation sensing system that includes first and second rotation angle sensing devices to determine reverse rotation, a gear mechanism operation device to shift the gear into neutral, and a drive stop device to halt fuel injection and ignition, minimizing the need for special mechanisms and reducing manufacturing and maintenance complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If combustion is stopped in the engine when reverse rotation is sensed, then water entry prevention is improved, but the gear mechanism remains complex and maintenance becomes laborious
Solution Approach 1:
The patent extracts the reverse rotation prevention function from the gear mechanism by introducing a separate control device that senses reverse rotation and stops combustion independently. This separates the water entry prevention function from the gear shifting mechanism, simplifying the gear mechanism while maintaining reliability.
Solution Approach 2:
The control device acts as an intermediary between the reverse rotation sensing and the combustion control. It receives reverse rotation signals and mediates the response by controlling fuel injection and ignition, thereby preventing water entry without requiring complex gear mechanism modifications.
2Reliability
If a reverse rotation sensing device is added to prevent water entry, then reliability is improved, but manufacturing cost increases
Solution Approach 1:
The control device serves multiple functions: it controls normal combustion operation, detects reverse rotation, and prevents water entry by stopping fuel injection and ignition. This multi-functionality consolidates what would otherwise require separate devices, reducing overall manufacturing cost while improving reliability.
Solution Approach 2:
The control device utilizes existing engine parameters and signals to detect reverse rotation and automatically triggers the appropriate protective action. The system is self-sufficient, using its own sensing capabilities and control outputs without requiring additional external devices or complex mechanical structures.
3Speed
If fuel injection is continued during reverse rotation, then engine responsiveness is improved, but water enters the engine
Solution Approach 1:
The control device continuously monitors engine rotation direction through the reverse rotation sensing function. When reverse rotation is detected, it immediately provides feedback by stopping fuel injection and ignition, creating a closed-loop control system that prevents water entry while maintaining normal operation during forward rotation.
Solution Approach 2:
The control device operates periodically by continuously monitoring rotation direction and alternately enabling or disabling fuel injection and ignition based on the detected rotation state. This periodic control ensures the engine responds appropriately to changing operational conditions without continuous mechanical intervention.
Data Source
AI summary
An engine in an outboard motor includes a first rotation angle sensing device arranged to sense a rotation angle of a crankshaft and second rotation angle sensing device arranged to sense a rotation angle of an exhaust camshaft. A reverse rotation determination section is arranged to determine an occurrence of a reverse rotation of the crankshaft based on of a rotation angle sensed by the first rotation angle sensing device and a rotation angle sensed by the second rotation angle sensing device. A gear mechanism operation section forceaby shifts a shift gear mechanism into a neutral state when a reverse rotation of the crankshaft is sensed by the reverse rotation determination section. Water is surely prevented from entering the internal combustion engine and can minimize an increase in the manufacturing cost and simplify the maintenance work of the internal combustion engine.