Electromechanical Actuator Brake Bushing for Precise Centering
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Solution Overview
Problem
Existing electromechanical actuators for shading devices face issues with the output member not being centered during assembly, leading to potential operating noise and reduced efficiency due to the force-fitting of the centring shaft into the gearbox and spring-applied brake components.
Innovation Solution
The actuator design includes a bushing mounted inside the input and output members of the spring-applied brake, ensuring centring even without the centring shaft being inserted, along with specific features like a cylindrical drum and planet carrier configurations to maintain precise alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the centring shaft is force-fitted into the bore of the input member and the bore of the sun gear to centre the output member, then the output member can be centred during assembly, but the operation of the spring-applied brake is constrained which generates operating noise and reduces efficiency
Solution Approach 1:
The invention divides the centring function into two separate components: the centring shaft provides initial positioning during assembly, while the bushing provides continuous centring support during operation. This segmentation allows each component to perform its specific function optimally without interfering with the other, resolving the contradiction between assembly precision and operational efficiency.
Solution Approach 2:
The bushing acts as an intermediary element between the centring shaft and the bore of the input member. It mediates the interaction by providing a low-friction interface that maintains centring precision while allowing the spring-applied brake to operate freely without constraint, thus eliminating operating noise and maintaining efficiency.
2Manufacturing precision
If the centring shaft is inserted into the bores to ensure centring, then assembly alignment is achieved, but the force-fitting constrains the spring-applied brake operation
Solution Approach 1:
The bushing serves as a mediator that decouples the centring function from the brake operation. It allows the centring shaft to maintain precise alignment while preventing direct contact between the centring shaft and the spring-applied brake components, thereby eliminating the source of operating noise.
Solution Approach 2:
The invention changes the friction parameter at the interface between the centring shaft and the input member bore by introducing the bushing. This parameter change from high friction (force-fitting) to low friction (bushing interface) maintains alignment precision while eliminating noise-generating constraints on brake operation.
3Ease of manufacture
If the output member is centred using force-fitting of the centring shaft, then assembly is simplified, but the efficiency of the spring-applied brake is reduced
Solution Approach 1:
The invention segments the centring and braking functions into separate components (centring shaft and bushing), allowing the assembly process to remain simple while the operational efficiency of the brake is preserved. The bushing is a simple addition that does not complicate assembly but significantly improves brake performance.
Solution Approach 2:
The bushing is designed to be self-installing within the bore of the input member, requiring no special tools or complex procedures. It automatically provides the necessary centring function while allowing the spring-applied brake to operate efficiently without additional assembly steps, thus maintaining ease of manufacture while improving efficiency.
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
This design ensures precise centring and reduces operational noise and enhances efficiency by maintaining proper alignment of the gearbox components during assembly, improving the overall performance of the electromechanical actuator.
Implementation Method 1
The drum comprises a friction surface, the friction surface being configured to cooperate with at least one turn of the coil spring
Implementation Method 2
The bushing is mounted inside the first bore of the input member with an interference fit. Furthermore, the bushing is mounted inside the second bore of the output member with a loose fit
Data Source
AI summary
An electromechanical actuator comprises a casing, an electric motor, a gearbox, a spring-applied brake (25) and a centring shaft (71). The brake (25) comprises a coil spring (48), a drum (49), an input member (50), an output member (51) and a bushing (76). The input member (50) comprises a first bore (72). The output member (51) comprises a first bore (73) and a second bore (74). The shaft (71) is mounted inside the first bore (73) of the output member (51) and a bore of a sun gear of a reduction stage of the gearbox. The bushing (76) comprises a bore (77), inside which the shaft (71) is mounted. The bushing (76) is mounted inside the first bore (72) of the input member (50) with an interference fit and inside the second bore (74) of the output member (51) with a loose fit.