Cam-Disc Fail-Safe Actuator Drive for Compact Spring Energy Storage

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Solution Overview

Problem

Existing fail-safe drives for actuators, such as valves, often have inefficient epicyclic gears when used in reverse to tension mechanical drive energy storage, necessitating an additional motor, which complicates their structure and integration.

Innovation Solution

A fail-safe drive with a compact design utilizing a disc spring energy storage system, including a cam, restoring elements, and a counter-element that converts axial movement into rotary movement, allowing for independent operation and integration within a compact actuator housing, with a locking device and damping mechanism for energy efficiency and safety.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If epicyclic gears are used in reverse to tension mechanical drive energy storage, then the fail-safe actuator can operate without an additional motor, but the efficiency is poor and structure becomes complicated

Engineering Contradiction:
Improvestructure complexityVSAvoidefficiency
Core Design Contradiction:
Device complexityVSLoss of energy

Solution Approach 1:

The patent inverts the conventional approach by using a cam disk with cam lobes instead of epicyclic gears to convert rotary motion to axial motion for tensioning the disc spring. This inversion eliminates the efficiency problems of reverse-gear operation while maintaining the ability to store mechanical energy without additional motors.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent extracts the gear mechanism entirely and replaces it with a cam-based system. By removing the epicyclic gears and using only a cam disk with appropriately shaped lobes, the design achieves both simpler structure and better efficiency simultaneously.

Inventive Principle:
Principle #2Taking out (Extraction)

2Volume of moving object

If a compact design is achieved using disc spring energy storage, then integration into actuator housing is easier, but space and structural constraints increase

Engineering Contradiction:
Improvehousing volumeVSAvoidintegration ease
Core Design Contradiction:
Volume of moving objectVSEase of manufacture

Solution Approach 1:

The patent merges the fail-safe drive mechanism directly into the actuator housing by using a compact cam disk design that integrates with the existing motor shaft and output components. The disc spring is positioned within the housing space, combining multiple functions into a unified compact structure that is easier to manufacture and integrate.

Inventive Principle:
Principle #5Merging (Combining)

3Loss of energy

If cam disk with cam lobes is used to convert rotary motion to axial motion, then efficiency improves, but manufacturing precision requirements increase

Engineering Contradiction:
ImproveefficiencyVSAvoidcam lobe profile precision
Core Design Contradiction:
Loss of energyVSManufacturing precision

Solution Approach 1:

The patent optimizes the cam lobe profile parameters through careful design to achieve efficient motion conversion while maintaining manufacturability. By adjusting the cam lobe geometry parameters (radius, angle, curvature), the design balances efficiency gains with reasonable manufacturing precision requirements that can be achieved through standard machining processes.

Inventive Principle:
Principle #35Parameter changes

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 a simpler, more efficient fail-safe drive that can be easily integrated into actuators, ensuring reliable operation during power failures with a compact design, constant output torque, and protection against damage through damping, while minimizing energy consumption.

Implementation Method 1

a drive energy storage device (6) comprising at least one disc spring (7)

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

a cam disk (8), at least one return element (7), in particular a return spring, a counter element (5), and an output shaft (3), wherein the cam disk (8) and the counter element (5) are configured to jointly convert an axial movement of the return element into a rotary movement of the output shaft (3)

Methodology Applied
Scientific EffectCam mechanism: Cam

Data Source

PatentEP4146966B1Fail-safe drive and actuating drive with a fail-safe drive
Publication Date: 2024.03.27 AUMA RIESTER GMBH & CO KG
  • EP4146966B1 patent drawingFigure 1
  • EP4146966B1 patent drawingFigure 2~3
  • EP4146966B1 patent drawingFigure 4~5

AI summary

The invention relates to improvements in the technical field of actuating drives. For this purpose, among other things, a fail-safe drive (1) for an actuating drive, which has a drive energy accumulator (6) comprising at least one disc spring (7) and a cam (8) for converting an axial drive movement of a restoring element into a rotational drive movement is proposed.