Cam-Disc Fail-Safe Drive for Constant Torque Actuation
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Solution Overview
Problem
Failsafe drives with epicyclic gear mechanisms have an unfavorable efficiency, particularly when used in reverse to tension a mechanical drive energy store, often requiring an additional motor, leading to a complex and inefficient design.
Innovation Solution
A failsafe drive utilizing a cup spring energy store, which can be tensioned by a drive motor, incorporating a cam disc, counter-element, and output shaft for converting axial movements into rotational movements, allowing for a compact and efficient design, and featuring a locking apparatus and movement damper for reliable operation and energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an epicyclic gear mechanism is used in the failsafe drive, then the drive can tension a mechanical drive energy store, but the efficiency becomes unfavorable and the construction becomes complex
Solution Approach 1:
The patent extracts the epicyclic gear mechanism from the failsafe drive design, replacing it with a direct coupling between the cup spring and the cam mechanism. This removal of the complex gear mechanism eliminates the efficiency losses and construction complexity while preserving the failsafe functionality through the spring-based energy storage system.
Solution Approach 2:
Instead of using a motor-driven gear mechanism to tension the spring (as in conventional designs), the patent inverts the approach by allowing the cup spring to directly drive the cam mechanism during failsafe operation. The spring is tensioned during normal operation and automatically releases energy during failsafe conditions, reversing the traditional power flow direction.
2Use of energy by moving object
If an epicyclic gear mechanism is used in reverse to tension the mechanical drive energy store, then the energy store can be charged, but the efficiency becomes unfavorable
Solution Approach 1:
The patent implements preliminary action by tensioning the cup spring during normal operational periods when energy is available, storing mechanical energy in advance for potential failsafe conditions. The cam mechanism is designed to accumulate energy in the spring during regular operation, preparing the system for emergency use without requiring energy-intensive reverse gear operation.
3Force
If a cam disc with control cams is used to convert axial movement to rotational movement, then the output torque can be kept constant, but the mechanism becomes more complex
Solution Approach 1:
The patent applies local quality by designing control cams with specific geometric profiles that vary along their length. Each cam profile is locally optimized to compensate for the non-linear spring characteristics at different compression stages, ensuring constant output torque is maintained only where needed in the operational range rather than throughout the entire mechanism.
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 failsafe drive with a compact design, ensuring constant output torque and movement, even with non-linear spring characteristics, and protects against shocks and jolts, while being energy-efficient and easily integratable into actuating drives.
Implementation Method 1
a drive energy store (6) which comprises at least one cup spring (7)
Implementation Method 2
a cam disc (8) for the common conversion of an axial drive movement of a restoring element (7) into a rotational drive movement
Implementation Method 3
featuring a locking apparatus and movement damper for reliable operation and energy efficiency
Data Source
AI summary
A fail-safe drive (1) for an actuating drive is provided, which has a cam disc (8), at least one restoring element, a counter-element (5) and an output shaft (3), with the cam disc (8) and the counter-element (5) being configured for joint conversion of an axial movement of the restoring element along the output shaft (3) into a rotational movement of the output shaft (3). The cam disc (8) has a control cam (10), the profile of which is adapted to a spring characteristic curve of the restoring element such that, in the case of activation of the failsafe drive (1), a constant output movement and/or a constant output torque can be generated.