Resin Wheel Train with Staged Rigidity for Torque and Wear

Solution Overview

Problem

In geared motors used in imaging devices, increasing torque to accommodate higher pixel counts leads to gear wear, and enlarging gear modules to reduce wear increases size, posing challenges in balancing torque and size reduction while minimizing noise.

Innovation Solution

A wheel train mechanism with gears made of resin materials, featuring increasing rigidity in three or more stages, and a module configuration where the final stage gear has a larger module than the front stage gear, and the fourth gear has lower rigidity than the third gear, to reduce wear and noise while maintaining high torque.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the module of each gear is increased to suppress wear, then the durability of gears is improved, but the size of the geared motor increases

Engineering Contradiction:

Improvegear durabilityVSAvoidgeared motor size

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The patent applies local quality by making each gear have different rigidity properties according to its position in the transmission chain. Specifically, gears are arranged in increasing order of rigidity from input to output stage, with the final stage gear having the highest rigidity. This localized differentiation allows each gear to have optimal properties for its specific loading conditions without requiring all gears to be oversized, thus suppressing wear while controlling overall size.

Inventive Principle:

Principle #3Local quality

2Force

If the torque output from the geared motor is increased, then the torque capability is improved, but the wear of gears increases

Engineering Contradiction:

Improvetorque outputVSAvoidgear wear resistance

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

The patent applies parameter changes by systematically varying the rigidity parameter of gears across different stages of the transmission mechanism. The rigidity of gears is changed in increasing order from the input stage to the output stage, with the final stage gear having the highest rigidity. This parameter progression allows the system to handle high torque outputs while distributing wear resistance appropriately across the transmission chain.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the rigidity of all gears is increased to reduce wear, then the gear durability is improved, but the cost of manufacturing increases

Engineering Contradiction:

Improvegear durabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies local quality by making each gear have different rigidity properties according to its position in the transmission chain. Specifically, gears are arranged in increasing order of rigidity from input to output stage, with the final stage gear having the highest rigidity. This localized differentiation allows each gear to have optimal properties for its specific loading conditions without requiring all gears to be oversized, thus suppressing wear while controlling overall size.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS10731729B2Wheel train mechanism, gear box, driving device, and electronic apparatus

Publication Date: 2020.08.04 SEIKO INSTR INC

AI summary

In a wheel train mechanism, a first speed reduction gear, a second speed reduction gear, a third speed reduction gear, a fourth speed reduction gear and an output gear are all made of a resin material. The third speed reduction gear and the fourth speed reduction gear are disposed at a rear stage of the second speed reduction gear and made of a material having rigidity higher than that of the first speed reduction gear and the second speed reduction gear. The output gear is disposed at a rear stage of the fourth speed reduction gear and is made of a material having rigidity higher than that of the fourth speed reduction gear.