Outboard Motor Shift Actuator Control for Gear Disengagement

Solution Overview

Problem

Outboard motors face challenges in disengaging gears during high-speed rotation due to strong meshing between the dog clutch and driven gear, leading to prolonged high current flow and potential durability issues in the shift actuator.

Innovation Solution

A control device that detects the operating position and state quantity of the shift actuator, suppressing ignition and fuel injection when the state quantity exceeds a threshold, allowing for rapid reduction in engine rotational speed and easing gear disengagement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the engine rotates at high speed, then the propeller generates sufficient thrust, but the dog clutch and driven gear strongly mesh making gear disengagement difficult

Engineering Contradiction:

Improveengine rotational speedVSAvoidgear disengagement

Core Design Contradiction:

SpeedVSEase of operation

Solution Approach 1:

The control unit suppresses ignition and fuel injection before the gear shifting operation is completed. This preliminary action reduces engine rotational speed in advance, weakening the meshing force between the dog clutch and driven gear, thereby enabling easy disengagement during the shifting process.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If the shift actuator continuously attempts to switch gear meshing at high speed, then gear shifting is maintained, but large current flows for long time reducing shift actuator durability

Engineering Contradiction:

Improvegear shifting capabilityVSAvoidshift actuator durability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The control unit suppresses ignition and fuel injection before the gear shifting operation is completed. This preliminary action reduces engine rotational speed in advance, weakening the meshing force between the dog clutch and driven gear, thereby enabling easy disengagement during the shifting process.

Inventive Principle:

Principle #10Preliminary action

3Ease of operation

If the shift actuator operates against strong gear meshing force, then gear switching is attempted, but prolonged high current flow occurs

Engineering Contradiction:

Improvegear switchingVSAvoidshift actuator current consumption

Core Design Contradiction:

Ease of operationVSUse of energy by moving object

Solution Approach 1:

The control unit suppresses ignition and fuel injection before the gear shifting operation is completed. This preliminary action reduces engine rotational speed in advance, weakening the meshing force between the dog clutch and driven gear, thereby enabling easy disengagement during the shifting process.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS11919614B2Outboard motor and outboard motor control device

Publication Date: 2024.03.05 HONDA MOTOR CO LTD

AI summary

An outboard motor is provided with: an encoder which detects the rotational speed of an engine; a position sensor which detects an operating position of a shift lever; and a state quantity detection unit which detects a state quantity of a shift actuator. A control device of the outboard motor determines whether the state quantity is more than or equal to a stop-initiating threshold value when the operating position has been switched. If the state quantity is more than or equal to the stop-initiating threshold value, the control device implements a stop control to stop ignition and/or fuel injection in the engine.