Marine Propulsion Shock Reduction Mechanism

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Solution Overview

Problem

The prior art marine vessel propulsion units face issues with wear of drive teeth and driven teeth due to shock absorption, inadequate shock absorption during rotational direction switching, and reduced torque transmission to the propeller shaft, leading to shortened mechanism life and inefficient propulsion.

Innovation Solution

A marine vessel propulsion unit incorporating an intermediate shaft, a forward-reverse switching mechanism, and a shock reduction mechanism with multiple spring members and stopper portions to absorb rotational shocks and prevent excessive deformation, ensuring reliable torque transmission to the propeller shaft.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If drive teeth and driven teeth are used to absorb shock through sliding movement, then shock absorption is achieved, but wear occurs and mechanism life is shortened

Engineering Contradiction:

Improveshock absorptionVSAvoidmechanism life

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

The patent replaces the mechanical sliding engagement of drive teeth and driven teeth with a spring member-based shock absorption system. The spring member elastically deforms to absorb shock forces, eliminating the need for sliding friction between teeth and thereby preventing wear while maintaining shock absorption capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The spring member acts as an intermediary element between the drive shaft and driven shaft. Instead of direct tooth-to-tooth contact, the spring member mediates the transmission of rotational forces while absorbing shock through elastic deformation, thus protecting the toothed components from wear.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If only one spring member is used for shock absorption, then device complexity is reduced, but shock absorption during rotational direction switching is insufficient

Engineering Contradiction:

Improvenumber of spring membersVSAvoidshock absorption capacity

Core Design Contradiction:

Device complexityVSForce

Solution Approach 1:

The patent divides the shock absorption function into multiple segments by using multiple spring members arranged around the central rotation axis. Each spring member handles a portion of the shock load, and collectively they provide sufficient shock absorption capacity during rotational direction switching while maintaining manageable device complexity.

Inventive Principle:

Principle #1Segmentation

3Force

If spring member supports drive teeth, then shock is absorbed, but torque transmission to propeller shaft is reduced

Engineering Contradiction:

Improveshock absorptionVSAvoidtorque transmission

Core Design Contradiction:

ForceVSPower

Solution Approach 1:

The patent employs a dynamic shock absorption system where the spring member elastically deforms only during shock events (such as rotational direction switching). During normal torque transmission, the spring member maintains its rigid structure and does not absorb torque, thereby ensuring full power transmission to the propeller shaft while still providing shock protection when needed.

Inventive Principle:

Principle #15Dynamics

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 shock reduction mechanism effectively minimizes wear and extends the life of the propulsion unit by absorbing rotational shocks and ensuring high torque transmission to the propeller shaft, improving propulsion efficiency and reducing mechanical stress.

Implementation Method 1

The plurality of spring members are arranged to absorb a force in the rotational direction by elastically deforming in the rotational direction when the force in the rotational direction is applied to the intermediate shaft

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentUS8092266B2Marine vessel propulsion unit

Publication Date: 2012.01.10 YAMAHA MOTOR CO LTD

AI summary

A marine vessel propulsion unit includes an engine, a drive shaft, a propeller shaft, a propeller, an intermediate shaft, a forward-reverse switching mechanism, and a shock reduction mechanism. The intermediate shaft is arranged on a central rotation axis of the propeller shaft. The intermediate shaft is arranged to transmit rotation between the drive shaft and the propeller shaft. The forward-reverse switching mechanism is arranged to switch a rotational direction of the propeller shaft to a forward drive direction or a reverse drive direction. The shock reduction mechanism includes a plurality of spring members and a pair of stopper portions. The shock reduction mechanism is arranged on the central rotation axis of the propeller shaft. The plurality of spring members are arranged to absorb a force in the rotational direction by elastically deforming in the rotational direction when the force in the rotational direction is applied to the intermediate shaft. The pair of stopper portions are arranged to prevent elastic deformations of the plurality of spring members by coming into contact with each other when the elastic deformation amounts of the plurality of spring members reach a predetermined value.