Marine Propulsion Engine Load Control for Gear Rattle Noise Reduction

Solution Overview

Problem

Conventional marine vessel propulsion devices experience gear rattle noise due to relative rotation speed fluctuations between the drive shaft and propeller shaft, which is typically addressed by increasing the number of mechanical components, leading to higher assembly costs and complexity.

Innovation Solution

A marine vessel propulsion device that uses an engine load generating unit to detect relative rotation speed and apply an opposing load, reducing the need for additional mechanical components by controlling the engine load through a power generator and control unit, thereby canceling out rotational fluctuations and minimizing gear rattle.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a damper structure is added to reduce gear rattle noise, then the abnormal noise is reduced, but the number of components increases and assembly cost increases

Engineering Contradiction:

Improvegear rattle noiseVSAvoidnumber of components

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical damper structure with an engine load control system that uses a power generator and control unit to detect and counteract relative rotation speed fluctuations between the drive shaft and propeller shaft, eliminating the need for additional mechanical components while reducing gear rattle noise

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The control unit detects the relative rotation speed between the drive shaft and propeller shaft and generates an engine load in opposition to the detected fluctuation, creating a feedback mechanism that actively counteracts the harmful vibrations without requiring mechanical dampers

Inventive Principle:

Principle #23Feedback

2Object-affected harmful factors

If a damper structure is added to reduce gear rattle noise, then the abnormal noise is reduced, but assembly man-hours increase

Engineering Contradiction:

Improvegear rattle noiseVSAvoidassembly man-hours

Core Design Contradiction:

Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The patent replaces the mechanical damper structure with an engine load control system that uses a power generator and control unit to detect and counteract relative rotation speed fluctuations between the drive shaft and propeller shaft, eliminating the need for additional mechanical components while reducing gear rattle noise

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system uses the engine's own power generation capability to create the counteracting load, allowing the engine to self-regulate its own rotational fluctuations without requiring external mechanical dampening components that would increase assembly complexity and time

Inventive Principle:

Principle #25Self-service

3Object-affected harmful factors

If a damper structure is added to reduce gear rattle noise, then the abnormal noise is reduced, but cost increases

Engineering Contradiction:

Improvegear rattle noiseVSAvoidassembly cost

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent replaces the mechanical damper structure with an engine load control system that uses a power generator and control unit to detect and counteract relative rotation speed fluctuations between the drive shaft and propeller shaft, eliminating the need for additional mechanical components while reducing gear rattle noise

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The power generator serves multiple functions: it generates electrical power from the engine and simultaneously acts as a variable load to counteract rotational fluctuations, eliminating the need for separate mechanical damper components and reducing overall system cost

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

The solution effectively reduces abnormal noise from relative rotation speed fluctuations without increasing the number of components, maintaining a simple structure and reducing assembly costs while stabilizing engine rotation.

Implementation Method 1

a power generator that is driven by power transmitted from the engine

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS8827758B2Marine vessel propulsion device

Publication Date: 2014.09.09 YAMAHA MOTOR CO LTD

AI summary

A marine vessel propulsion device includes an engine, a propeller shaft, a drive shaft that is rotated by power transmitted from the engine, a dog clutch that transmits rotation of the drive shaft to the propeller shaft, and an engine load generating unit. The engine load generating unit detects relative rotation speed between the drive shaft and the propeller shaft, and generates an engine load opposite in phase to the relative rotation speed detected therebetween.