Rotary Drive Device Compact Design Using Internal Ring Gear

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Solution Overview

Problem

Existing rotary drive devices face challenges in achieving compact dimensions while accommodating high electrical power requirements, as the electric drive motor needs larger dimensions when operated purely electrically, compromising the device's compactness.

Innovation Solution

A coaxial feed-through channel through the gear housing allows for the placement of a larger drive motor without increasing the device's transverse dimensions by shifting the engagement area of the drive pinion and ring gear closer to the axis of rotation, enabling the use of a compact design with increased electrical power.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the electric drive motor is dimensioned larger to accommodate high power requirements, then the power capability is improved, but the transverse dimensions of the device increase

Engineering Contradiction:
Improveelectrical power capabilityVSAvoidtransverse dimensions
Core Design Contradiction:
PowerVSArea of stationary object

Solution Approach 1:

The patent transitions from external side-by-side gear arrangement to internal concentric ring gear configuration, utilizing the axial dimension and radial space within the housing to accommodate a larger motor without increasing transverse footprint. The ring gear with internal teeth allows the drive pinion to mesh internally, shifting the engagement area closer to the rotation axis and enabling compact motor placement.

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

Solution Approach 2:

The drive pinion is nested within the ring gear structure, with the pinion axially penetrating into the ring gear's internal gearing. This nested configuration allows both gear components to occupy overlapping spatial volumes, maximizing space utilization and enabling a larger motor to be mounted on the rear of the housing without increasing external dimensions.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Power

If the engagement area is positioned closer to the axis of rotation, then the motor size can be increased, but the distance from the motor to the output part increases

Engineering Contradiction:
Improvemotor sizeVSAvoidaxial length
Core Design Contradiction:
PowerVSLength of moving object

Solution Approach 1:

The patent divides the power transmission path into distinct functional segments: the ring gear handles torque multiplication close to the output, while the drive pinion transmits power from the motor. This segmentation allows optimization of each component's position and size independently, accommodating a larger motor while maintaining efficient power transmission.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The ring gear acts as an intermediary between the drive pinion and the output part. By positioning the ring gear internally with its own teeth engagement, it mediates the power transmission from the pinion to the output, allowing the motor to be placed further axially without increasing the overall transmission path length.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP2956689B1Electrically actuated rotary drive device
Publication Date: 2016.07.13 FESTO AG & CO KG
  • EP2956689B1 patent drawingFigure 1
  • EP2956689B1 patent drawingFigure 2
  • EP2956689B1 patent drawingFigure 3

AI summary

The invention relates to an electrically actuated rotary drive device (1), which has a gearing housing (4), to a rear side of which an electric drive motor (2) is fastened and on which an output part (12) having a drive connection to the drive motor (2) is rotatably supported. The drive connection is realised by gearing means (7) arranged in the gearing housing (4), which gearing means comprise an output gear (47), which is arranged on the output part (12) and is designed as a ring gear (47a) having internal teeth (52), and a drive pinion (24), which is provided with external teeth (26) and belongs to the drive motor (2). The drive pinion (24) protrudes into the ring gear (47a) inside the gearing housing (4).