Planetary Clamping Gear for Self-Locking Jaw Position Retention

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Solution Overview

Problem

Existing gripping or clamping devices with worm gear systems suffer from inefficiencies, require axial adjustment, and incur high bearing demands due to axial forces, while also lacking reliable position retention when the drive is not actuated.

Innovation Solution

The use of a self-locking or partially retarding planetary gear system as the gear unit, which ensures that the jaw element maintains its position without reversing even when the drive is not engaged, offering greater efficiency, higher power transmission, a more compact design, and smoother operation compared to worm gear systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a worm gear system is used for position retention, then the jaw element can be maintained in position when the drive is not actuated, but the system suffers from poor efficiency, high axial forces requiring additional bearings, and the need for axial adjustment

Engineering Contradiction:
Improveposition retentionVSAvoidefficiency
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent changes the fundamental gear type from worm gear to planetary gear with specific tooth profile parameters. The planetary gear uses a positive stationary transmission ratio design where the sun gear (input) and ring gear (output) engage through planetary gears mounted on a carrier. By optimizing the tooth profiles and engagement geometry, the system achieves self-locking behavior through friction and geometric constraints rather than the inherent self-locking of worm gears, thereby improving efficiency while maintaining position retention reliability.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If a worm gear system is used, then position retention is achieved, but the device requires additional bearings and axial adjustment mechanisms due to high axial forces

Engineering Contradiction:
Improveposition retentionVSAvoidbearing requirements
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the worm gear component entirely, replacing it with a planetary gear system that inherently handles force distribution differently. The planetary gear configuration distributes radial and axial loads across multiple planetary gears and bearing points, eliminating the need for specialized axial adjustment mechanisms and reducing the overall bearing requirements while maintaining position retention functionality.

Inventive Principle:
Principle #2Taking out (Extraction)

3Loss of energy

If a planetary gear system is used instead of worm gear, then efficiency and power transmission are improved, but the self-locking behavior must be carefully designed to ensure position retention

Engineering Contradiction:
ImproveefficiencyVSAvoidposition retention
Core Design Contradiction:
Loss of energyVSReliability

Solution Approach 1:

The patent employs a composite approach combining multiple gear elements (sun gear, planetary gears, ring gear, carrier) with different functional characteristics. The system integrates power transmission elements with self-locking elements through the specific configuration where the planetary gears engage both the sun gear and ring gear simultaneously. This composite gear structure allows efficient power transmission while the geometric constraints and friction between multiple meshing surfaces provide the necessary self-locking behavior for position retention.

Inventive Principle:
Principle #40Composite materials

4Reliability

If a worm gear system is used, then position retention is achieved, but the design is less compact and operation is less smooth compared to planetary gears

Engineering Contradiction:
Improveposition retentionVSAvoiddesign compactness
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The patent merges multiple gear stages and functions into a single planetary gear unit. The planetary configuration allows the input shaft (sun gear), output shaft (ring gear), and self-locking mechanism to be integrated in a compact arrangement around a common axis. This consolidation eliminates the need for separate worm gear components and axial adjustment mechanisms, achieving superior compactness while maintaining position retention through the inherent self-locking behavior of the planetary gear configuration.

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

The planetary gear system effectively maintains the gripping force and position even when the drive is not active, while providing improved efficiency, power transmission, and a more compact design, thus addressing the limitations of worm gear systems.

Implementation Method 1

the gear unit has an input shaft and an output shaft, wherein the input shaft can be or is coupled to a drive and wherein the output shaft can be or is coupled to the at least one jaw element

Methodology Applied
Scientific EffectGear meshing: Gear

Implementation Method 2

a 'self-retarding planetary gear' means that a load torque at the actual drive, which thereby becomes the drive, can be increased up to a destruction limit without the load torque causing movement of the planetary gear, in particular the input shaft. Increasing the load torque increases, among other things, the opposing frictional forces.

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP4556176A1Gripping and/or clamping device with an inhibiting gear
Publication Date: 2025.05.21 SCHUNK GMBH & CO KG
  • EP4556176A1 patent drawingFigure 1
  • EP4556176A1 patent drawingFigure 4~5

AI summary

The invention relates to a gripping or clamping device (10) with a base housing (12), with at least one jaw element (14) arranged to be movable in the base housing (12) and with a gear unit (18), wherein the gear unit (18) has an input shaft (24) and an output shaft (28), wherein the input shaft (24) can be or is coupled to a drive (16) and wherein the output shaft (28) can be or is coupled to the at least one jaw element (14), and wherein the gear unit (18) is designed as an inhibiting planetary gear (18A).