Compact Gear With Radial Teeth And Load Sharing

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Solution Overview

Problem

Existing transmissions face limitations in achieving high torque transmission with a small diameter due to uneven load distribution and torsional deformation, particularly in single-stage gears with multiple ring gears, which restricts their effectiveness in transmitting large torques efficiently.

Innovation Solution

A transmission design featuring a coaxial ring gear and inner shaft with multiple cam disks, where the teeth are radially movable and coupled via a tooth carrier, and load sharing means are implemented to ensure even torque distribution across ring gears, counteracting torsional deformations and optimizing load distribution for high torque transmission with a small diameter.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If multiple ring gears are provided to increase torque transmission capacity, then the torque transmission capability is improved, but uneven load distribution and torsional deformation occur reducing effectiveness

Engineering Contradiction:
Improvetorque transmission capabilityVSAvoidload distribution uniformity
Core Design Contradiction:
ForceVSReliability

Solution Approach 1:

The transmission is divided into multiple independent ring gears (first ring gear, second ring gear, etc.) that can be selectively engaged. Each ring gear operates semi-independently, allowing the system to distribute torque across multiple segments rather than overloading a single ring gear, thereby improving torque capacity while maintaining load distribution balance

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent employs movable teeth that can radially move between engaged and disengaged positions, allowing dynamic adjustment of which ring gears are active. This dynamic engagement mechanism enables the system to adapt load distribution in real-time, preventing uneven loading and torsional deformation while maintaining high torque transmission capability

Inventive Principle:
Principle #15Dynamics

2Force

If the diameter of the ring gear is increased to transmit larger torques, then the torque transmission capability is improved, but the installation space requirement increases

Engineering Contradiction:
Improvetorque transmission capabilityVSAvoidinstallation space
Core Design Contradiction:
ForceVSArea of stationary object

Solution Approach 1:

Instead of increasing torque capacity by enlarging the ring gear diameter (two-dimensional expansion), the patent adds multiple ring gears stacked along the axial direction (third dimension). This allows the transmission to handle larger torques by utilizing axial space rather than radial space, maintaining a compact installation footprint while achieving high torque transmission capability

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

Solution Approach 2:

Multiple ring gears are arranged concentrically and stacked along the inner shaft, creating a nested configuration where each ring gear occupies a different axial position. This nesting approach allows multiple torque transmission paths to coexist within a compact radial envelope, enabling high torque capacity without proportionally increasing the overall transmission diameter

Inventive Principle:
Principle #7Nested doll (Nesting)

3Force

If the width of the teeth is increased to transmit larger torques, then the torque transmission capability is improved, but the manufacturing complexity and space requirements increase

Engineering Contradiction:
Improvetorque transmission capabilityVSAvoidtooth structure complexity
Core Design Contradiction:
ForceVSDevice complexity

Solution Approach 1:

The torque transmission function is segmented across multiple ring gears with standard-width teeth rather than concentrating the load on fewer wide teeth. Each ring gear uses conventional tooth dimensions, avoiding the need for complex wide-tooth designs while achieving high torque capacity through parallel load distribution across multiple segments

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The movable teeth mechanism allows the system to dynamically engage multiple ring gears, distributing the torque load across more teeth than would be simultaneously engaged in a static wide-tooth design. This dynamic load distribution enables the use of standard tooth widths while achieving equivalent or superior torque transmission capability

Inventive Principle:
Principle #15Dynamics

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 design allows for efficient transmission of large torques with a small diameter, ensuring even load distribution across ring gears, enhancing the transmission's utilization and adaptability to various installation situations while minimizing deformation-related issues.

Implementation Method 1

at least two, preferably at least three or at least five cam disks being arranged on the inner shaft

Methodology Applied
Scientific EffectCam mechanism: Cam

Implementation Method 2

A bearing means is preferably arranged on the cam disks, which is suitable for reducing friction between the teeth and the cam disk. For example, a large number of rollers can be arranged on the cam disk

Methodology Applied
Scientific EffectRolling friction: Roller

Data Source

PatentEP2381132B1Gearing
Publication Date: 2019.05.15 WITTENSTEIN SE
  • EP2381132B1 patent drawingFigure 1
  • EP2381132B1 patent drawingFigure 2a~2b
  • EP2381132B1 patent drawingFigure 3a~4b

AI summary

The gear (1) has a hollow wheel (2) with internal teeth (5), and two toothed rings provided with respective radially movable teeth (6, 7) for engaging into the internal teeth. Two cam disks (16, 17) are fastened on an inner shaft for radially driving the respective teeth. A load dividing unit divides transmitted torque between the toothed rings, where the torque is transmitted by the toothed rings. The toothed rings with additional teeth (8-10) and cam disks (18-20) are arranged on the inner shaft for driving the additional teeth. Transmission ratio of the gear is 1 to 10.