Outboard Motor Neutral Start Control via Shift Actuator Sensor
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Solution Overview
Problem
Existing watercraft propulsion systems with remote control engines face issues where the engine can be inadvertently started in gear due to mechanical disconnects between the shift lever and actuator, leading to potential abrupt movements and requiring additional space for neutral safety switches, which affect responsiveness.
Innovation Solution
A watercraft propulsion system with a shifting mechanism, shift actuator, shift position sensor, and controller that deactivates the engine starter using semiconductor devices when the shift position sensor detects a non-neutral position, ensuring the engine only starts in neutral, incorporating a start-regulation circuit with logic circuits for improved responsiveness and space efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a neutral safety switch mechanism is installed to detect neutral state, then engine starting safety is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent combines the neutral detection function with the existing shift position sensor that detects the position of the shift actuator. The controller uses the same sensor to determine both the shift position and whether the system is in neutral state, eliminating the need for a separate neutral safety switch mechanism while maintaining engine starting safety.
Solution Approach 2:
The shift position sensor serves multiple functions: it detects the position of the shift actuator for gear selection and simultaneously provides neutral state detection for engine starting control. This multi-functional use of the sensor reduces device complexity while ensuring safety.
2Device complexity
If software-based neutral detection is used, then device complexity is reduced, but responsiveness of engine starting deteriorates
Solution Approach 1:
The patent replaces software-based neutral detection with a hardware-based start-regulation circuit that directly receives the shift position signal and controls the starter relay. This hardware circuit provides immediate electrical control of the starter motor without software processing delays, significantly improving engine starting responsiveness.
Solution Approach 2:
The start-regulation circuit continuously monitors the shift position signal and is pre-configured to immediately cut off power to the starter relay when a non-neutral position is detected. This preliminary preparation ensures that even if the engine is attempted to be started in gear, the starter is de-energized before cranking can occur, eliminating software response delays.
3Ease of operation
If the shift lever and shift actuator are mechanically disconnected, then ease of operation is improved, but reliability of neutral detection deteriorates
Solution Approach 1:
The patent implements a feedback system where the shift position sensor continuously monitors the actual position of the shift actuator and provides real-time signals to the controller. This feedback ensures that even when the shift lever is mechanically disconnected from the actuator, the system accurately detects the actual gear position and prevents engine starting in non-neutral states.
Data Source
AI summary
An outboard motor of a watercraft can include a shifting mechanism for performing gear shifting among forward, neutral, and reverse positions. A shift actuator can be configured to drive the shifting mechanism. A shift position sensor can be configured to detect a position of the shift actuator with respect to the forward, neutral, and reverse positions. A controller can be configured to control the shift actuator in accordance with a signal provided from the shift position sensor. A start-regulation circuit can have a plurality of semiconductor devices configured to deactivate a starting motor of the engine when a starting switch of the engine is turned on in a state where a position other than neutral is detected by the shift position sensor.