Rotary Actuator Retaining Element for Play-Free Positioning

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Solution Overview

Problem

Existing pivoting units fail to securely hold components in rotational end positions, leading to instability and inaccuracies during machining or relocation processes.

Innovation Solution

A pivoting unit with a housing-mounted drive and a retaining element, featuring conical contact sections and a biased holding mechanism, ensures secure engagement of the pivoting part in defined rotational end positions through a combination of mechanical stops and compressed air actuation, allowing for precise and repeatable positioning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional swivel units are used without additional retaining mechanisms, then the structure remains simple, but the swiveling part cannot be securely held in end positions, leading to instability and play

Engineering Contradiction:
Improveholding accuracyVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

A retaining element is introduced as an intermediary component between the swiveling part and the housing. This retaining element features a conical contact section that engages with a complementary conical counter-contact section on the swiveling part, providing secure positioning in end positions while maintaining structural clarity and ease of understanding.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The retaining element and counter-contact section utilize conical (curved) surfaces instead of flat or cylindrical contacts. The conical contact section with its specific half-angle creates a self-centering, play-free engagement that securely holds the swiveling part in end positions through geometric constraint rather than complex mechanical linkages.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Manufacturing precision

If mechanical stops alone are used to define end positions, then the device remains simple, but play and positioning inaccuracies occur in the end positions

Engineering Contradiction:
Improvepositioning accuracyVSAvoidmechanism complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The conical contact surfaces create a geometric locking mechanism where the swiveling part is forced into precise end positions by the angled surfaces of the retaining element and counter-contact section. This curved surface engagement eliminates play and achieves high positioning accuracy without requiring complex adjustment mechanisms or multiple components.

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Reliability

If the retaining element is always engaged to prevent play, then positioning accuracy is maintained, but the swiveling part cannot be moved between end positions

Engineering Contradiction:
Improvepositioning stabilityVSAvoidmovability
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The retaining element is designed to be movable along the axis of rotation rather than fixed. It can be retracted axially to release the conical contact engagement, allowing the swiveling part to be freely rotated between end positions. When pressed axially, the retaining element engages the conical counter-contact section to lock the position, providing dynamic switching between movable and locked states.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

A pneumatic actuator with a piston is used to move the retaining element axially. By applying pneumatic pressure to the piston, the retaining element is pushed into engagement with the conical counter-contact section to lock the swiveling part in end positions. Releasing the pneumatic pressure allows a spring to retract the retaining element, enabling free movement between positions.

Inventive Principle:
Principle #29Pneumatics and hydraulics

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 solution provides secure and repeatable positioning of the pivoting part in rotational end positions without play, enabling accurate machining or relocation of components, while allowing adjustable end positions within a certain range through screw adjustments.

Implementation Method 1

The retaining element 50 is pre-tensioned towards the pivoting part 12 by means of a coil spring 62

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The drive piston 30 longitudinally defines two pressure chambers 34, which can be alternately pressurized with compressed air via compressed air inlets 36

Methodology Applied
Scientific EffectPressurisation: Pressurisation

Implementation Method 3

The retaining element 50 also defines a pressure chamber 64 that can be pressurized with compressed air

Methodology Applied
Scientific EffectPressurisation: Pressurisation

Data Source

PatentEP2909485B1Rotary actuator
Publication Date: 2020.10.14 SCHUNK GMBH & CO KG
  • EP2909485B1 patent drawingFigure 1
  • EP2909485B1 patent drawingFigure 2~4
  • EP2909485B1 patent drawingFigure 5~8

AI summary

The invention relates to a pivot unit (10) that has a pivot part (12) that can pivot from a first rotational end position into a second rotational end position and has a drive (16), which is provided in a housing (14), for pivoting said pivot part (12). A retaining element (50) that can be moved transversely to the direction of rotation of the pivot part (12) is provided in such a way that, when a rotational end position has been reached, said retaining element (50) is moved from a releasing position into a retaining position and the pivot part (12) is thereby held in the rotational end position.