Compact Reducer Design with Radially Overlapping Planetary Gears

Solution Overview

Problem

Existing power tools with reducers have a large axial size and are less durable due to the use of long pins that can break or deform, limiting their efficiency and durability.

Innovation Solution

A power tool design featuring a reducer with two stages of internal gears and carriers aligned axially, where the preceding and succeeding planetary gears radially overlap with a single pin, reducing the axial size and enhancing durability by minimizing mechanical loss and using shorter pins.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If a single pin is used to support planetary gears in axially-adjacent stages, then the axial size of the reducer is reduced, but the pin becomes longer and more prone to breaking or deformation

Engineering Contradiction:

Improveaxial size of reducerVSAvoiddurability of pin

Core Design Contradiction:

Length of moving objectVSReliability

Solution Approach 1:

The reducer is divided into multiple independent stages, each with its own carrier and pin. The first stage has a first carrier with a first pin supporting the first planetary gear, and the second stage has a second carrier with a second pin supporting the second planetary gear. This segmentation allows each pin to be shorter and more reliable while maintaining compact axial dimensions through the staged arrangement of carriers along the axial direction.

Inventive Principle:

Principle #1Segmentation

2Device complexity

If axially-adjacent internal gears are used with a single carrier, then the device complexity is reduced, but the axial length increases and durability decreases

Engineering Contradiction:

Improvestructure of reducerVSAvoidaxial length

Core Design Contradiction:

Device complexityVSLength of moving object

Solution Approach 1:

The reducer is divided into multiple independent stages, each with its own carrier and pin. The first stage has a first carrier with a first pin supporting the first planetary gear, and the second stage has a second carrier with a second pin supporting the second planetary gear. This segmentation allows each pin to be shorter and more reliable while maintaining compact axial dimensions through the staged arrangement of carriers along the axial direction.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS11945092B2Power tool

Publication Date: 2024.04.02 MAKITA CORP

AI summary

A power tool includes a reducer that has a small size in an axial direction and is highly durable, although including a transmission mechanism. The power tool includes a motor, a reducer that reduces rotation from the motor, and an actuator to be actuated by the rotation reduced by the reducer. The reducer includes at least two stages of internal gears aligned in an axial direction, a preceding planetary gear and a succeeding planetary gear adjacent to each other in the axial direction to revolve within the internal gears, and at least two stages of carriers aligned in the axial direction. A carrier of the carriers supports the preceding planetary gear and the succeeding planetary gear radially overlapping each other with a single pin.