Flexible Ring Gear in Planetary Actuator
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Solution Overview
Problem
Electromechanical actuators for closing, screening, or solar protection installations with planetary-type reduction gears suffer from non-uniform contact pressure distribution along the length of engagement, leading to excessive stress and wear on the toothing, which can result in breakage.
Innovation Solution
The use of an epicyclic-type reduction gear with satellite pinions having separate toothing parts and made of a rigid metallic material, while the ring gear is made of a flexible plastic material, allows for uniform contact pressure distribution by enabling angular offset and deformation, preventing oblique alignment of planet pinions during rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electromechanical actuators with planetary reduction gears are used, then the structure is simple and manufacturing is easy, but the contact pressure distribution along the engagement length is non-uniform, leading to excessive stress and wear on the toothing
Solution Approach 1:
The planetary gear is divided into multiple independent satellite pinions instead of a single continuous gear. Each satellite pinion can deform independently, allowing for more uniform distribution of contact pressure along the engagement length with the ring gear, thereby reducing excessive stress and wear on the toothing.
Solution Approach 2:
The patent changes the material parameters by using a plastic ring gear instead of a metallic one. The plastic material provides greater flexibility and deformability, which allows the ring gear to adapt to the rotation of the input shaft and maintain uniform contact pressure distribution with the satellite pinions throughout the engagement length.
2Productivity
If the input shaft is driven by the electric motor, then the actuator performs its function, but non-uniform contact pressure generates excessive stress that can cause breakage of planetary gear teeth
Solution Approach 1:
The plastic ring gear acts as a cushioning element that absorbs and distributes the stresses generated during operation. Its deformable nature allows it to compensate for load variations and prevent excessive stress concentration on the planetary gear teeth, thereby preventing breakage before it occurs.
Solution Approach 2:
By changing the material of the ring gear from rigid metal to flexible plastic, the patent fundamentally alters the stress distribution parameters. The plastic material's ability to deform under load creates a more favorable stress distribution pattern that protects the planetary gear teeth from excessive stress and potential breakage during actuator operation.
3Volume of moving object
If only a portion of the planetary gear engagement length is used to transmit force, then the gear dimensions can be reduced, but wear is observed over only a portion of the engagement length
Solution Approach 1:
The patent introduces dynamic behavior to the previously static engagement pattern. The plastic ring gear deforms dynamically during rotation, continuously adapting its shape to maintain contact across the entire engagement length of all satellite pinions. This dynamic adaptation ensures uniform wear distribution and improves reliability while allowing for optimized gear dimensions.
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 configuration ensures uniform contact pressure distribution, reduces stress on components, and prevents breakage by allowing the ring gear to deform and follow the movement of satellite pinions, thereby extending the lifespan of the actuator.
Implementation Method 1
the ring gear is made of a flexible plastic material, allows for uniform contact pressure distribution by enabling angular offset and deformation
Data Source
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AI summary
An electromechanical actuator comprises an electric motor and a gearbox (19). The gearbox (19) includes at least one reduction stage (25a, 25b, 25c) which comprises at least one planetary gear (32c), one ring gear (37c), and a plurality of satellite gears (33c). The planetary gear (32c) is configured to cooperate with each satellite gear (33c). Each satellite gear (33c) meshes with an internal tooth profile (38c) of the ring gear (37c). Each satellite gear (33c) comprises at least a first tooth profile (39) and a second tooth profile (40). The planetary gear (32c) and the satellite gears (33c) are made of a first material. Furthermore, the ring gear (37c) is made of a second material. The rigidity of the first material of the planetary gear (32c) and satellite gears (33c) is greater than the rigidity of the second material of the ring gear (37c).