Internal Carbon Fiber Resin Gear Pairing to Reduce Tooth Damage

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Solution Overview

Problem

Carbon fiber reinforced resin gears experience early damage due to exposed fibers on the tooth surface during external meshing, leading to damage of both the resin-made gear and the mating gear.

Innovation Solution

The gear device configuration is modified to have a metal external gear and carbon fiber reinforced resin internal gears, which mesh internally, reducing tooth contact pressure and sliding speed, thus minimizing damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If carbon fiber reinforced resin is used for external meshing gears, then weight reduction is achieved, but the exposed carbon fibers on the tooth surface cause early damage to both the resin gear and the mating gear

Engineering Contradiction:

Improvegear weightVSAvoidgear durability

Core Design Contradiction:

Weight of moving objectVSReliability

Solution Approach 1:

The patent inverts the traditional external meshing configuration by using internal meshing instead. In internal meshing, the carbon fiber reinforced resin gear meshes with a metal gear internally, which prevents the exposed carbon fibers from attacking the mating gear surface, thereby resolving the durability issue while maintaining weight reduction benefits

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the meshing type parameter from external to internal meshing. This parameter change fundamentally alters the contact mechanics between gears, reducing the harmful effects of exposed carbon fibers and enabling the use of carbon fiber reinforced resin without compromising gear durability

Inventive Principle:

Principle #35Parameter changes

2Strength

If carbon fiber reinforced resin is used for gear material, then strength is improved, but tooth contact pressure and sliding speed cause damage during external meshing

Engineering Contradiction:

Improvegear strengthVSAvoidtooth surface damage

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

By inverting from external to internal meshing, the patent changes the direction and nature of contact between teeth. This inversion reduces the sliding speed and contact pressure at the tooth surface, preventing damage while allowing the high strength of carbon fiber reinforced resin to be fully utilized

Inventive Principle:

Principle #13The other way round (Inversion)

3Ease of manufacture

If external meshing configuration is used with carbon fiber reinforced resin gears, then manufacturing is simplified, but the exposed fibers attack the mating gear surface

Engineering Contradiction:

Improvegear manufacturingVSAvoidfiber exposure damage

Core Design Contradiction:

Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The patent resolves the harmful effect of exposed fibers by inverting to internal meshing configuration. This configuration change prevents the fibers from being exposed on the outer tooth surface that contacts the mating gear, eliminating the damage mechanism while keeping the manufacturing process relatively simple

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS11649887B2Gear device

Publication Date: 2023.05.16 SUMITOMO HEAVY IND LTD

AI summary

A gear device includes an external gear, and an internal gear that meshes with the external gear. The external gear is formed of metal. The internal gear is formed of a carbon fiber reinforced resin.