Spring Brake Centering in Electromechanical Actuators
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Solution Overview
Problem
Existing electromechanical actuators for blackout devices face issues with the spring brake operation noise and efficiency due to improper centering during assembly, which is exacerbated by the press fitting of the centering shaft.
Innovation Solution
The electromechanical actuator design incorporates a bearing mounted inside the input and output members of the spring brake, allowing for precise centering without the need for a centering shaft, and includes features like a cylindrical drum with a specific diameter and planet carrier bores for improved assembly and operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the output member is force-fitted into the bore of the sun gear and the bore of the input member, then the assembly is secured, but the output member is not centered relative to the input member inside the spring brake, leading to operating noise and degraded performance
Solution Approach 1:
A centering shaft is introduced as an intermediary element between the output member and the input member. The centering shaft fits into the bore of the sun gear and the bore of the input member, providing a precise centering reference that ensures the output member is properly aligned within the spring brake during assembly, thereby eliminating operating noise and maintaining performance
2Ease of manufacture
If the output member is force-fitted into the bore of the sun gear and the bore of the input member, then the assembly is secured, but the centering shaft insertion is constrained, risking operating noise and degraded spring brake performance
Solution Approach 1:
The centering shaft is pre-installed into the bore of the sun gear and the bore of the input member before assembling the output member. This preliminary action establishes the correct centering geometry in advance, allowing the output member to be easily fitted without constrained force fitting, thus maintaining both ease of manufacture and spring brake performance
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 quiet and efficient operation of the spring brake by maintaining precise centering and reducing assembly constraints, thereby enhancing the overall performance and reliability of the blackout device.
Implementation Method 1
a drum (49), the drum (49) comprising a friction surface (57), the friction surface (57) being configured to cooperate with at least one turn of the helical spring (48)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An electromechanical actuator comprises a housing, an electric motor, a gearbox, a spring brake (25), and a centering shaft (71). The brake (25) comprises a helical spring (48), a drum (49), an input member (50), an output member (51), and a bearing (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 bearing (76) comprises a bore (77) within which the shaft (71) is mounted. The bearing (76) is mounted inside the first bore (72) of the input member (50) with a tight fit and inside the second bore (74) of the output member (51) with a loose fit.