Gearbox Cam Disk Pivoting Segment Fatigue Reduction

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Solution Overview

Problem

Existing gear transmissions with radially displaceable teeth and cam disks experience fatigue due to low friction and high loads, leading to reduced service life, particularly in the mounting of swivel segments on the cam disk.

Innovation Solution

The transmission design incorporates rigid teeth made from metal or plastic alloys with a cam disk and a ring gear, featuring a bearing system with pivoting segments supported by roller bearings and a profiled surface to prevent slipping, along with a non-circular cam disk shape for varied gear ratios, and a tooth carrier with parallel rows of rolling elements for enhanced stability and reduced friction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If simple roller bearings are used between pivoting segments and cam disk, then friction is reduced, but fatigue occurs leading to reduced service life

Engineering Contradiction:
ImprovefrictionVSAvoidservice life
Core Design Contradiction:
Loss of energyVSReliability

Solution Approach 1:

A lubricant is introduced as an intermediary substance between the roller bearings and the cam disk surface. The lubricant forms a protective film that reduces direct metal-to-metal contact, thereby reducing friction while preventing fatigue and extending service life of the pivoting segments

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The surface properties of the cam disk are modified by applying a coating or treatment that changes the friction and wear characteristics. This parameter change allows the surface to maintain low friction while increasing resistance to fatigue and extending the service life of the bearing system

Inventive Principle:
Principle #35Parameter changes

2Strength

If rigid teeth made from metal or plastic alloys are used, then load capacity and rigidity are increased, but manufacturing complexity increases

Engineering Contradiction:
Improveload capacityVSAvoidmanufacturing complexity
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The teeth are manufactured as composite structures combining metal and plastic materials. The metal provides structural strength and rigidity to handle high loads, while the plastic portions can be molded into complex tooth profiles, thereby achieving high load capacity while maintaining ease of manufacture through composite material properties

Inventive Principle:
Principle #40Composite materials

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 significantly increases the service life of gear transmissions by reducing fatigue and maintaining high rigidity and load capacity, while allowing for high gear ratios and efficient power transmission.

Implementation Method 1

roller bearings, which in turn rest on the cam disk

Methodology Applied
Scientific EffectRolling friction: Roller

Implementation Method 2

Despite the low friction of the roller bearing, signs of fatigue can occur in this area

Methodology Applied
Scientific EffectFriction reduction: Friction

Data Source

PatentEP3168497B1Gearbox and the use of a gearbox
Publication Date: 2020.01.08 WITTENSTEIN SE
  • EP3168497B1 patent drawingFigure 1

AI summary

Gearbox (1), in particular coaxial gearbox or linear gearbox, comprising a toothing (40), a tooth carrier with radially oriented guides, teeth (25, 27) which are received in the guides for engagement with the toothing, wherein the teeth (25, 27) are mounted in the guides so as to be radially displaceable in the direction of their longitudinal axis relative to the tooth carrier, a cam disk (3) for radially driving the teeth (25, 27), wherein the cam disk has a circumferential profile, rolling elements (15, 17) which are arranged on the profile, and a plurality of pivot segments (19) for supporting the teeth (25, 27), wherein the pivot segments are arranged on the rolling elements (15, 17), wherein the rolling elements (15, 17) are arranged on the profile in at least two rows of rolling elements parallel in the circumferential direction of the cam disk.