Two-Stage Cycloid Gear with Coaxial Cam Disks

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Solution Overview

Problem

Cycloidal gears in prior art are limited in degree of reduction and miniaturization, leading to low strength and high manufacturing costs due to fine pitch cam sections and small bolt diameters, making them unsuitable for precision engineering applications.

Innovation Solution

A cycloidal gear design featuring two gear stages with cam disks eccentrically coupled and arranged coaxially, allowing for larger reductions and increased torque transmission, with the second gear stage having thicker cam disks and larger bolt diameters to enhance strength and manufacturability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If single-stage cycloidal gears are used to achieve high reductions, then the degree of reduction is improved, but the cam sections become very small (fine pitch) and bolt diameters become very small, leading to lower strength and lower transmissible torque

Engineering Contradiction:
Improvetransmissible torqueVSAvoidcam section and bolt strength
Core Design Contradiction:
PowerVSStrength

Solution Approach 1:

The transmission system is divided into two separate gear stages, each handling a portion of the total reduction ratio. This segmentation allows each stage to use larger cam sections and bolts, maintaining strength while achieving the overall high reduction. The first stage reduces speed by a first ratio, and the second stage further reduces it by a second ratio, with both stages using robust mechanical components.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from a single-stage two-dimensional design to a multi-stage three-dimensional axial arrangement. The two gear stages are positioned at different axial locations, allowing the system to achieve high reduction ratios without compromising component strength. This spatial arrangement enables each stage to operate independently with optimized component sizes.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Power

If single-stage cycloidal gears are used to achieve high reductions, then the degree of reduction is improved, but manufacturing cost increases due to difficulty of manufacturing small curve sections and small bolts

Engineering Contradiction:
Improvedegree of reductionVSAvoidmanufacturing cost
Core Design Contradiction:
PowerVSEase of manufacture

Solution Approach 1:

By dividing the high reduction ratio into two separate stages, each stage can use larger, easier-to-manufacture cam sections and bolts. This segmentation makes the manufacturing process more feasible and cost-effective, as standard manufacturing techniques can be applied to larger components rather than requiring specialized processes for very small precision parts.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the design parameters from fine-pitch small components to coarser-pitch larger components distributed across two stages. This parameter change makes the components easier to manufacture with standard tolerances and reduces manufacturing complexity, thereby lowering production costs while maintaining the desired reduction ratio.

Inventive Principle:
Principle #35Parameter changes

3Power

If single-stage cycloidal gears are used, then the structure is simple, but the degree of reduction is limited and miniaturization is restricted

Engineering Contradiction:
Improvedegree of reductionVSAvoidgear stage structure
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The transmission system is segmented into two modular gear stages that can be manufactured and assembled separately. Each stage is a complete functional unit with its own cam disks, driving pins, and support structure. This modular segmentation allows for easier manufacturing and assembly while achieving higher overall reduction ratios than a single stage could provide.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The two gear stages are arranged axially one after the other, with the second stage positioned along the axis of the first stage. This nested axial arrangement allows the system to achieve high reduction ratios in a compact configuration, with each stage contributing to the overall reduction while maintaining a relatively compact overall structure.

Inventive Principle:
Principle #7Nested doll (Nesting)

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

Enables large gear reductions with high transmissible torques while being cost-effective, overcoming the limitations of single-stage cycloidal gears by providing a compact and robust design.

Implementation Method 1

cam disks transmit a rolling torque. For this purpose, an eccentric drives a cam disk with cycloid cam sections of the number n, which rolls in a bolt ring with n+1 bolts

Methodology Applied
Scientific EffectRolling: Roller

Implementation Method 2

a drive shaft that can be driven in rotation about a gear axis and is eccentrically coupled in movement to the cam discs of the first gear stage

Methodology Applied
Scientific EffectEccentric movement: Eccentric

Data Source

PatentEP3301324B1Cycloid gear
Publication Date: 2019.08.21 SCHUNK GMBH & CO KG
  • EP3301324B1 patent drawingFigure 1
  • EP3301324B1 patent drawingFigure 2
  • EP3301324B1 patent drawingFigure 3

AI summary

Cycloidal transmission with a first transmission stage comprising a first and a second cam disk, each having cam sections, which are coupled by a plurality of drive pins, with a drive shaft rotatably driven about a transmission axis, which is eccentrically coupled to the cam disks of the first transmission stage, and with at least one first output shaft arranged coaxially to the transmission axis, wherein a second transmission stage is provided comprising a first and a second cam disk, each having cam sections, which are coupled by a plurality of drive pins, wherein the cam disks of the second transmission stage are eccentrically coupled to the first output shaft.