Planetary Gear Grease Retention for Friction Reduction

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Solution Overview

Problem

Existing planetary gear decelerators in image forming apparatuses face issues with power loss and abrasion due to rotational friction, particularly when the sun gear shifts and contacts a partner member, and existing solutions like spherical surfaces on the sun gear are not effective in preventing abrasion over extended use.

Innovation Solution

The implementation of a planetary gear mechanism with a grease retaining portion that keeps grease near the contact areas between the sun gear and the contact member, ensuring continuous lubrication and reducing frictional losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If the sun gear shifts in the direction of thrust due to engagement with planetary gears and contacts a partner member, then the thrust load is transmitted, but power loss and abrasion occur due to rotational friction at the contact portion

Engineering Contradiction:

Improvethrust load transmissionVSAvoidpower loss due to rotational friction

Core Design Contradiction:

ForceVSLoss of energy

Solution Approach 1:

A grease retaining portion is introduced as an intermediary structure between the sun gear and the partner member. This portion stores grease and supplies it to the contact surface, mediating the interaction to reduce rotational friction while maintaining thrust load transmission capability

Inventive Principle:

Principle #24Intermediary (Mediator)

2Force

If the sun gear shifts in the direction of thrust and contacts a partner member, then the thrust load is transmitted, but abrasion occurs at the contact portion

Engineering Contradiction:

Improvethrust load transmissionVSAvoiddurability against abrasion

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

The grease retaining portion acts as an intermediary that continuously supplies grease to the contact surface between the sun gear and partner member. This lubricating film prevents direct metal-to-metal contact, thereby reducing abrasion and improving durability while maintaining the necessary thrust load transmission

Inventive Principle:

Principle #24Intermediary (Mediator)

3Loss of energy

If a spherical surface is provided on the sun gear to reduce contact area, then rotational friction is reduced, but the spherical surface gets abraded after extended use

Engineering Contradiction:

Improverotational friction reductionVSAvoiddurability of spherical surface

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

Instead of relying solely on the spherical geometry to reduce friction, a grease retaining portion is introduced as a lubricant supply mechanism. The grease continuously replenishes the contact area, preventing the spherical surface from wearing down through extended use while maintaining low rotational friction

Inventive Principle:

Principle #24Intermediary (Mediator)

4Reliability

If grease is supplied to the spherical portion of the sun gear, then abrasion is prevented, but the grease spatters due to centrifugal force of rotation

Engineering Contradiction:

Improveprotection against abrasionVSAvoidgrease spattering

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The grease retaining portion is designed to extract and hold grease in a controlled manner, separating the grease supply function from the rotating sun gear. The grease is retained in a stationary or slowly moving structure, preventing centrifugal spattering while still providing lubrication to the contact surface

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The grease retaining portion serves as an intermediary structure that decouples the grease supply from the high-speed rotation. It holds the grease in place and delivers it to the contact area without being subjected to the full centrifugal forces, thereby preventing spattering

Inventive Principle:

Principle #24Intermediary (Mediator)

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 solution effectively reduces power loss and abrasion by maintaining a consistent grease supply at the contact points, enhancing the durability and efficiency of the drive transmission unit in image forming apparatuses.

Implementation Method 1

The grease retaining portion retains grease near a contact portion at which the sun gear contacts the contact member as the sun gear moves in the direction of thrust due to engagement with the plurality of planetary gears

Methodology Applied

Scientific EffectLubrication: Lubrication

Data Source

PatentUS8845472B2Drive transmission unit and image forming apparatus including same

Publication Date: 2014.09.30 RICOH CO LTD

AI summary

A drive transmission unit includes a planetary gear mechanism. The planetary gear mechanism includes an outer gear rotatably disposed on a shaft, a sun gear rotated by a power source, coaxially disposed on the same shaft as the outer gear, multiple planetary gears to engage the sun gear and the outer gear, disposed along an inner circumferential surface of the outer gear, a carrier rotatable on the same shaft as the outer gear to rotatably support the planetary gears, a contact member that contacts the sun gear as the sun gear moves in a direction of thrust due to engagement with the plurality of planetary gears, and a grease retaining portion to retain grease near a contact portion at which the sun gear contacts the contact member as the sun gear moves in the direction of thrust. The outer gear, the sun gear, and the planetary gears are helical gears.