Planetary Gear Unit Axial Force Management

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Solution Overview

Problem

Existing planetary gear units experience energy losses due to internal friction from axial components of tooth forces, which are undesirable in smooth operation, especially in timing gears.

Innovation Solution

The use of angular ball bearings to support sun gears, allowing axial components of tooth forces to be absorbed and transmitted to the surrounding structure, reducing the need for separate axial and radial bearings and enhancing the gear unit's ability to handle both axial and radial forces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If axial components of tooth forces are absorbed by friction surfaces, then the sun gears are supported axially, but energy is consumed due to internal friction

Engineering Contradiction:

Improveaxial support stabilityVSAvoidenergy loss due to friction

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent replaces the friction-based axial support mechanism with a ball bearing mechanism. The ball bearing absorbs axial components of tooth forces through rolling contact instead of sliding friction, significantly reducing energy losses while maintaining reliable axial support for the sun gears

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the fundamental parameter of contact type from sliding friction to rolling contact. By introducing ball bearings, the interaction between sun gears and supporting structure transitions from high-friction sliding to low-friction rolling, thereby reducing energy consumption while maintaining load-bearing capacity

Inventive Principle:

Principle #35Parameter changes

2Force

If a combination of axial bearing and radial bearing is used to support sun gears, then both axial and radial forces can be absorbed, but the installation space requirement increases

Engineering Contradiction:

Improveaxial and radial force absorptionVSAvoidinstallation space

Core Design Contradiction:

ForceVSArea of stationary object

Solution Approach 1:

The patent merges the functions of axial bearing and radial bearing into a single angular ball bearing. This combined bearing simultaneously absorbs both axial and radial force components, eliminating the need for separate bearings and thereby reducing the overall installation space requirement while maintaining comprehensive force absorption capability

Inventive Principle:

Principle #5Merging (Combining)

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 configuration minimizes energy loss by effectively managing axial forces and maintaining smooth operation with reduced installation space requirements, improving the efficiency of the planetary gear unit.

Implementation Method 1

The angular ball bearing has a comparatively small installation space requirement compared to a combination consisting of an axial bearing and a radial bearing, with which the sun gear could be supported and can absorb higher axial forces than a radial deep-groove ball bearing.

Methodology Applied

Scientific EffectBall bearing: Ball Bearing

Data Source

PatentUS9051996B2Planetary gear unit

Publication Date: 2015.06.09 SCHAEFFLER TECHNOLOGIES AG & CO KG

AI summary

A planetary gear unit, having at least one first set of first planetary wheels arranged at a radial distance to a central axis, which mesh with a first sun gear that is rotatable around the central axis. The planetary gear unit further includes at least one second set of second planetary wheels arranged at a radial distance to the central axis, where the second planetary wheels mesh with a second sun gear that is rotatable around the central axis.