Fail-Safe Actuator Assembly with Dual Drive Trains and Spring Return
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Solution Overview
Problem
Existing fail-safe actuators for moving parts between two end positions are not compact in structure and flexible in use, particularly in applications like HVAC and emergency ventilation systems, where they need to ensure a safe position in case of drive failure.
Innovation Solution
A fail-safe actuator design featuring a first and second drive train with a mechanical rotary entrainment device, an energy storage device, and an externally actuatable holding device, allowing for compact and flexible operation by enabling the actuator to move parts between two end positions using either drive train independently or together, with energy storage and release mechanisms for safe positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fail-safe actuator uses a single drive train with energy storage device, then the structure is simpler, but the operational flexibility and reliability are reduced
Solution Approach 1:
The actuator is divided into two independent drive trains (first and second drive trains), each capable of independently actuating the part. This segmentation allows the system to maintain operational flexibility by using either drive train independently, while also improving reliability through redundancy. Each drive train has its own holding device that can be independently activated, enabling versatile operational modes including single-drive operation and coordinated dual-drive operation.
2Adaptability or versatility
If a fail-safe actuator uses two independent drive trains, then the operational flexibility is improved, but the device complexity increases
Solution Approach 1:
The two drive trains are merged through a common output shaft and integrated holding devices, allowing them to function as a unified system when both are operational. The mechanical coupling through the output shaft enables the drive trains to work together synergistically, reducing the effective complexity by creating a coordinated system rather than two completely separate mechanisms. The integrated holding devices can be selectively activated to manage the combined system efficiently.
3Area of stationary object
If the actuator uses mechanical rotary entrainment device with stop surfaces, then the radial space requirement is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The stop surfaces are pre-positioned on the drive train components during manufacturing to establish precise mechanical engagement points. This preliminary positioning ensures that when the drive trains engage through the stop surfaces, the rotational alignment and torque transfer occur at predetermined, precisely defined locations. The pre-established geometric relationships between stop surfaces eliminate the need for complex real-time adjustment mechanisms, maintaining manufacturing precision while minimizing radial space requirements.
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 actuator ensures reliable and flexible operation, allowing for quick energy introduction and storage, enabling the part to be moved into specified positions efficiently, even in case of drive failure, with compact design and reduced radial space requirements.
Implementation Method 1
an energy storage device, e.g. at least one elastic spring element, which is coupled with the second drive train
Data Source
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AI summary
A fail-safe actuator for moving a part has in each case a drive (18, 118) by means of which a first or a second drive train (24, 26) can be moved. The drive trains (24, 26) in each case have their own output shaft (34, 38) and can be actuated independently of one another. An energy storage device is coupled with the second output shaft (38), wherein a holding device selectively holds the energy or releases it from the energy storage device, so that the second output shaft (38) can be moved. A rotary entrainment of the first output shaft (34) ensures that in the event of a failure of the drive (18) this is moved into a specified end position. The two output shafts (34, 38) are set in motion via gear wheels (32, 36) if the drive trains are actuated. An assembly unit consisting of actuator and moved part is also described.