Split Planet Carrier Layout for Backlash-Free Planetary Gears

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Solution Overview

Problem

Existing planetary gear transmissions require high assembly effort and risk of backlash due to the need for separate planetary gear sets and spring elements, which can lead to misalignment and increased design complexity.

Innovation Solution

A planetary gear transmission design featuring a planet carrier with two parts that can be rotated relative to each other, allowing planet gears to adjust their position along a common trajectory with the sun and ring gear, using external disks and adjusting screws for securement and adjustment, thereby simplifying the adjustment of backlash.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a conventional planetary gear transmission is used, then gear engagement and power transmission are achieved, but complex assembly and disassembly procedures are required due to multiple fastening elements

Engineering Contradiction:
Improveassembly procedureVSAvoidfastening elements
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent merges multiple fastening functions into a single snap ring that simultaneously secures the planet carrier to the sun gear and retains the planet gears. This consolidation eliminates the need for multiple separate fastening elements, directly resolving the technical contradiction by reducing device complexity while maintaining assembly ease.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The snap ring is designed as a segmented component with multiple equidistantly spaced segments that can elastically deform during assembly. This segmentation allows the single fastening element to accommodate manufacturing tolerances and facilitate simpler assembly procedures while maintaining secure engagement, thus addressing both assembly ease and device complexity.

Inventive Principle:
Principle #1Segmentation

2Reliability

If multiple fastening elements are used to secure planet carrier, then reliable power transmission is achieved, but manufacturing cost and assembly time increase

Engineering Contradiction:
Improvepower transmissionVSAvoidassembly time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The snap ring combines multiple fastening functions into a single component that secures both the planet carrier to the sun gear and the planet gears in place. This merger maintains reliable power transmission while reducing assembly time by eliminating the need to install multiple separate fastening elements, directly addressing the technical contradiction.

Inventive Principle:
Principle #5Merging (Combining)

3Power

If conventional gear transmission components are used, then power transmission functionality is achieved, but environmental pollution occurs due to gear oil leakage

Engineering Contradiction:
Improvepower transmissionVSAvoidgear oil leakage
Core Design Contradiction:
PowerVSObject-generated harmful factors

Solution Approach 1:

The snap ring acts as a flexible retaining component that seals the gear transmission components within the housing. By securely holding the planet gears and planet carrier in place, the snap ring prevents gear oil leakage, thus eliminating environmental pollution while maintaining power transmission functionality.

Inventive Principle:
Principle #30Flexible shells and thin films

4Productivity

If precise gear engagement is achieved through tight tolerances, then power transmission efficiency is improved, but manufacturing complexity and cost increase

Engineering Contradiction:
Improvepower transmission efficiencyVSAvoidgear engagement tolerance
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The elastomeric snap ring provides a cushioning effect that compensates for manufacturing tolerances in gear engagement. The elastic deformation capability of the snap ring absorbs dimensional variations, allowing for less precise manufacturing while maintaining effective power transmission, thus resolving the technical contradiction between productivity and manufacturing precision.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentEP3990804B1Backlash-free planetary gear
Publication Date: 2024.07.03 KNORR BREMSE SYSTEME FUER NUTZFAHIZEUGE GMBH
  • EP3990804B1 patent drawingFigure 1~2
  • EP3990804B1 patent drawingFigure 3~4
  • EP3990804B1 patent drawingFigure 4A~4B

AI summary

The invention relates to a planetary gear transmission with a sun gear (2), a ring gear (1), at least one first planet gear (3), and at least one second planet gear (4). The first planet gear (3) and the second planet gear (4) are arranged on a planet carrier (7), and the sun gear (3), the ring gear (1), the first planet gear (3), and the second planet gear (4) mesh with one another. The planetary gear transmission is characterized in that the planet carrier (7) has a first planet carrier part (8) and a second planet carrier part (9). The first planet carrier part (8) and the second planet carrier part (9) are designed such that the planet carrier parts are rotated relative to each other starting from a base position and can be fixed in their respective rotated position relative to each other, wherein the at least one first planet gear (3) is connected to the first planet carrier part (8), and the at least one second planet gear (4) is connected to the second planet carrier part (9).