Outboard Motor Speed Reduction Mechanism Axial Compactness

Solution Overview

Problem

The existing outboard motor speed change devices increase in size when a speed reduction mechanism is added, leading to dimensional issues and increased overall size.

Innovation Solution

The outboard motor incorporates a speed reduction mechanism with an inner gear, planetary gear, and sun gear configuration, where the shaft portion of the carrier overlaps with the sun gear, and the output shaft is coupled to the carrier, allowing for a compact design that prevents size increase, with the speed reduction mechanism located closer to the propeller shaft and engine, and utilizing spline-fitting for concentric arrangement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a speed reduction mechanism is added to the conventional speed change device, then the rotational speed of the input shaft can be reduced and power transmitted to the output shaft, but the dimension of the speed change device in the axial direction becomes larger

Engineering Contradiction:

Improverotational speed reductionVSAvoidaxial dimension of speed change device

Core Design Contradiction:

SpeedVSLength of moving object

Solution Approach 1:

The speed reduction mechanism is nested within the existing speed change device structure. The input shaft of the speed reduction mechanism is integrated with the output shaft of the speed change device, and the output shaft of the speed reduction mechanism is integrated with the propeller shaft. This nesting allows the speed reduction function to be added without increasing the overall axial dimension of the device.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The speed reduction mechanism is merged with the speed change device by sharing common shafts and structural elements. The input shaft of the speed reduction mechanism serves as the output shaft of the speed change device, and the output shaft of the speed reduction mechanism serves as the propeller shaft. This merging eliminates the need for separate mounting spaces and reduces the axial dimension.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If a speed reduction mechanism is added to the conventional speed change device, then power transmission can be stabilized, but the overall size of the outboard motor increases

Engineering Contradiction:

Improvepower transmission stabilityVSAvoidoverall size of outboard motor

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The speed reduction mechanism is nested within the existing speed change device structure. The input shaft of the speed reduction mechanism is integrated with the output shaft of the speed change device, and the output shaft of the speed reduction mechanism is integrated with the propeller shaft. This nesting allows the speed reduction function to be added without increasing the overall axial dimension of the device.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The speed reduction mechanism is merged with the speed change device by sharing common shafts and structural elements. The input shaft of the speed reduction mechanism serves as the output shaft of the speed change device, and the output shaft of the speed reduction mechanism serves as the propeller shaft. This merging eliminates the need for separate mounting spaces and reduces the axial dimension.

Inventive Principle:

Principle #5Merging (Combining)

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

This configuration effectively shortens the length of the speed reduction mechanism in the axial direction, maintains a compact size, and ensures efficient power transmission to the propeller without increasing the motor's dimensions.

Implementation Method 1

a planetary gear that meshes with the inner gear and that rolls inside the inner gear

Methodology Applied

Scientific EffectPlanetary gear mechanism: Gear

Implementation Method 2

The speed reduction mechanism includes an inner gear that is connected with the input shaft, a planetary gear that meshes with the inner gear and that rolls inside the inner gear, and a sun gear that meshes with the planetary gear

Methodology Applied

Scientific EffectMechanical advantage: Mechanical Advantage

Implementation Method 3

the shaft portion of the carrier and the output shaft are coupled by spline-fitting so as to be concentrically arranged

Methodology Applied

Scientific EffectSpline-fitting: Mechanical Fastener

Data Source

PatentUS8118701B2Outboard motor

Publication Date: 2012.02.21 YAMAHA MOTOR CO LTD

AI summary

In an outboard motor, a speed reduction mechanism includes an inner gear connected with an input shaft (i.e., second output shaft), a planetary gear that meshes with the inner gear and that rolls inside the inner gear, and a sun gear that meshes with the planetary gear and that is not rotatable. A shaft portion of a carrier that supports the planetary gear, and a shaft core portion of the sun gear, preferably have a cylindrical or substantially cylindrical shape. The shaft portion of the carrier is inserted and arranged to overlap with the shaft core portion of the sun gear in a direction perpendicular or substantially perpendicular to the shaft. The output shaft (i.e., drive shaft) is inserted and coupled to the shaft portion of the carrier. Accordingly, this provides an outboard motor that makes it possible to prevent the size of a speed change device from increasing in size when a speed reduction mechanism is added.