Spring Brake Drum Grooves for Quiet Electromechanical Actuators
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Solution Overview
Problem
Electromechanical actuators for home automation and solar protection systems experience noise issues during operation, particularly due to frictional instability between the spring brake's coils and the drum's internal surface, which worsens with temperature and repeated cycles.
Innovation Solution
A method of manufacturing the drum with a mechanical surface treatment that creates grooves on the internal surface to improve lubrication and reduce noise, combined with a thermochemical surface treatment and application of a solid lubricant to enhance frictional stability and maintain lubrication between the coil spring and the drum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the spring brake operates with metal-to-metal contact between coil and drum housing, then the brake can provide sufficient friction force for activation, but frictional instability and noise increase during operation
Solution Approach 1:
A lubricant is introduced as an intermediary substance between the coil spring and the drum housing internal surface. This lubricant layer mediates the contact interface, reducing direct metal-to-metal interaction while maintaining sufficient friction for brake activation. The lubricant eliminates noise and frictional instability by preventing adhesion phases between metal surfaces.
Solution Approach 2:
The surface properties of the drum housing internal surface are modified through mechanical surface treatment to create a specific roughness profile. This parameter change in surface texture optimizes lubricant retention and distribution, ensuring stable lubrication conditions that reduce noise while maintaining adequate friction force for brake operation.
2Object-generated harmful factors
If mechanical surface treatment is applied to the drum housing internal surface, then lubrication is improved and noise is reduced, but manufacturing complexity increases
Solution Approach 1:
The internal surface of the drum housing undergoes mechanical surface treatment that modifies its physical parameters, specifically creating a controlled roughness profile. This parameter change optimizes the surface for lubricant retention and distribution, achieving noise reduction while maintaining a relatively simple manufacturing process using conventional surface treatment techniques.
3Force
If the coil spring rotates in the second direction to activate the brake, then friction force increases for braking, but noise and frictional instability worsen
Solution Approach 1:
The lubricant acts as a mediator during the braking operation when the coil spring rotates in the second direction. It maintains a lubricated contact interface that provides sufficient friction force for effective braking while preventing metal-to-metal adhesion that causes noise and frictional instability, thus resolving the contradiction between needing high friction and avoiding noise.
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 effectively reduces operating noise and frictional instability, ensuring reliable and quiet operation of the spring brake across varying temperatures and cycles.
Implementation Method 1
an internal friction surface of the housing of the drum is configured to cooperate with at least one coil of the coil spring... The step of mechanical surface treatment of the internal surface of the housing of the drum is a step of generating streaks on the inner surface of the housing
Implementation Method 2
The generation of operating noises of the spring brake is due to frictional instability resulting from adhesion phases and sliding phases of at least one turn of the spring brake with respect to the internal surface of the housing of the drum
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A method relates to the manufacture of a drum (23) for a spring brake for an electromechanical actuator, the drum (23) comprising a housing (26) configured to house at least one helical spring, an input member and an output member. The housing (26) has an internal friction surface (27) configured to cooperate with at least one coil of the helical spring. The method comprises at least one step of mechanical surface treatment of the inner surface (27) of the housing (26) of the drum (23), the mechanical surface treatment of the inner surface (27) of the housing (26) of the drum (23) being a step of creating grooves (50a, 50b) on the inner surface (27) of the housing (26).