Planetary Gear Fixing Member for Vessel Propulsion Backlash Reduction

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Solution Overview

Problem

Existing vessel propulsion apparatuses face challenges in securely fixing the planetary gear train due to circumferential backlash between the bearing carrier member and the gear case, leading to unreliable fixation of the housing to the lower case, which affects torque transmission and stability.

Innovation Solution

A vessel propulsion apparatus with a fixing member bolted to both the case and housing, ensuring the sun gear, ring gear, and carrier are not rotatable with respect to the housing, thereby securely fixing the planetary gear train and reducing backlash.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the anchoring member is inserted in the recess provided in the gear case, then the movement in the circumferential direction is restricted, but the width of the anchoring member is smaller than the width of the recess, resulting in circumferential clearance gap and backlash

Engineering Contradiction:

Improvefixation stabilityVSAvoidbacklash reduction

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent applies local quality by making the anchoring member's width in the circumferential direction equal to or greater than the width of the recess, specifically designing the anchoring member with protruding portions that extend beyond the recess boundaries. This local dimensional adjustment eliminates the circumferential clearance gap while maintaining the recess structure for radial positioning.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Instead of making the recess wider than the anchoring member (conventional approach), the patent inverts the design by making the anchoring member wider than or equal to the recess. This inversion eliminates the clearance gap that causes backlash, transforming the anchoring member from a fit-within-component to an over-extending component that prevents circumferential movement.

Inventive Principle:

Principle #13The other way round (Inversion)

2Strength

If the housing is fixed to the lower case using the anchoring member and bolt, then the planetary gear train is housed securely, but the circumferential clearance gap causes the housing to not be fixed firmly, affecting torque transmission

Engineering Contradiction:

Improvefixation strengthVSAvoidtorque transmission

Core Design Contradiction:

StrengthVSForce

Solution Approach 1:

The patent applies local quality by specifically adjusting the circumferential dimension of the anchoring member to equal or exceed the recess width, creating protruding portions that eliminate circumferential clearance. This localized dimensional change ensures firm fixation in the circumferential direction while maintaining overall fixation strength for torque transmission.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent inverts the conventional design approach by making the anchoring member wider than the recess in the circumferential direction, rather than fitting the anchoring member within the recess boundaries. This inversion eliminates the clearance gap that compromises torque transmission, ensuring the housing is firmly fixed to the lower case.

Inventive Principle:

Principle #13The other way round (Inversion)

3Power

If the sun gear is fixed in the rotational direction by the housing, then high torque is applied from the sun gear to the housing, but without firm fixation the sun gear cannot be reliably secured to the lower case

Engineering Contradiction:

Improvetorque applicationVSAvoidfixation reliability

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The patent applies local quality by specifically designing the anchoring member's circumferential width to equal or exceed the recess width, creating protruding portions that eliminate circumferential clearance. This localized dimensional adjustment ensures the housing is firmly fixed to the lower case, enabling reliable transmission of high torque from the sun gear without slippage or backlash.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent inverts the conventional design by making the anchoring member wider than the recess in the circumferential direction. This inversion eliminates the clearance gap that would cause unreliable fixation under high torque, ensuring the sun gear's rotational force is reliably transmitted through the housing to the lower case.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS8926466B2Vessel propulsion apparatus

Publication Date: 2015.01.06 YAMAHA MOTOR CO LTD

AI summary

A vessel propulsion apparatus includes a prime mover, a propeller shaft, a planetary gear train, a lower case, a cylindrical housing, and a fixing member. The planetary gear train is disposed on a propeller axis. The propeller shaft and the planetary gear train are housed in the lower case. The housing surrounds the propeller shaft about the propeller axis inside the lower case. The housing supports a sun gear such that the sun gear is not rotatable with respect to the housing. The fixing member is fixed to both the lower case and the housing.