Planetary Gear Carrier Stiffness Balancing for Pin Alignment
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Solution Overview
Problem
In planetary gear reduction devices with a rotatable carrier, misalignment occurs due to torque and centrifugal forces, leading to bending and twisting deformations of planetary pins, which are not adequately addressed by existing configurations.
Innovation Solution
The device employs a carrier design with equalized stiffness regions to balance twist and radial tensile forces, using a flexible structure in the front plate to equalize twist stiffness and a stronger structure in the rear plate to equalize radial tensile stiffness, preventing pin misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the carrier is made stiffer to reduce twist deformation under torque, then the twist stiffness improves, but the radial tensile stiffness under centrifugal force becomes excessive causing pin tilting
Solution Approach 1:
The carrier is divided into two regions with different stiffness characteristics: a first region (front plate) with lower twist stiffness to accommodate torque reactions, and a second region (rear plate) with higher radial tensile stiffness to resist centrifugal forces. This local differentiation allows each region to be optimized for its specific functional requirement without compromising the other.
Solution Approach 2:
The carrier is segmented into a front plate and a rear plate connected by coupling members, allowing independent optimization of stiffness properties in each segment. The front plate is designed with lower twist stiffness while the rear plate maintains higher radial tensile stiffness, resolving the contradiction between torque accommodation and centrifugal force resistance.
2Stability of the object's composition
If the front plate stiffness is reduced to accommodate torque reactions, then the twist deformation is reduced, but the radial tensile stiffness under centrifugal force is insufficient causing pin tilting
Solution Approach 1:
The front plate is designed with local quality characteristics that provide adequate twist flexibility while maintaining sufficient radial tensile stiffness through strategic material distribution and structural design in specific regions.
Solution Approach 2:
The front plate is segmented into regions with different stiffness properties, allowing the outer regions to be more flexible for torque accommodation while inner regions maintain higher stiffness for radial force resistance.
3Power
If the output frame is connected closer to the front plate, then the torque transmission is improved, but the torque reaction force creates imbalanced twist deformation
Solution Approach 1:
The carrier and output frame connection is designed asymmetrically, with the output frame connected to a portion of the radially outer portion closer to the front plate. This asymmetric configuration, combined with the differentiated stiffness regions, balances the torque reaction forces while maintaining effective power transmission.
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 effectively prevents misalignment of planetary pins by balancing twist and centrifugal forces, ensuring precise operation even at high rotational speeds.
Implementation Method 1
the carrier has a first region as an external force transmission path between the front pin support surfaces and the output frame, and a second region as the external force transmission path between the rear shaft support surfaces and the output frame, and a stiffness with respect to a twist force of the first region and a stiffness with respect to the twist force of the second region are equal to each other
Implementation Method 2
the outer portion of the front plate includes a flexible structure portion which makes the stiffness with respect to the twist force lower than that of the outer portion of the rear plate
Implementation Method 3
in the front plate and the rear plate, a stiffness with respect to a radial tensile force applied to the front pin support surfaces and a stiffness with respect to the radial tensile force applied to the rear shaft support surfaces are equal to each other
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An output frame is connected to a portion of a radially outer portion of a carrier, the portion being closer to a front plate than to a rear plate. The carrier has a first region as an external force transmission path between front pin support surfaces and the output frame, and a second region as the external for transmission path between rear shaft support surfaces and the output frame, and a stiffness with respect to a twist force of the first region and a stiffness with respect to the twist force of the second region are equal to each other. In the front plate and the rear plate, a stiffness with respect to a radial tensile force applied to the front pin support surfaces and a stiffness with respect to the radial tensile force applied to the rear shaft support surfaces are equal to each other.