Hollow Speed Reducer Layout for Cable Routing Without Size Growth
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Solution Overview
Problem
Industrial machines, such as robots, face a challenge in increasing the hollow diameter of speed reducers to accommodate more auxiliary devices while maintaining performance and reducing size, as the number of cables penetrating through the hollow space increases, contradicting the demand for reduced size and built-in cables.
Innovation Solution
A speed reducer design with a cylindrical case and internal teeth, featuring a carrier and crank shafts arranged on an imaginary circle, allowing for a hollow ratio within specific ranges to increase the hollow diameter without enlarging the speed reducer's size, while maintaining a predetermined reduction ratio and necessary strength, facilitating easier passage of cables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of cables penetrating through the hollow space is increased to accommodate more auxiliary devices, then the functionality of the robot is improved, but the hollow diameter requirement increases which contradicts the demand for reduced size
Solution Approach 1:
The patent transitions from a traditional single-dimension hollow structure to a multi-dimensional arrangement by positioning multiple crank shafts on a circumference of an imaginary circle. This spatial reconfiguration allows cables to be routed through optimized paths in three-dimensional space, effectively increasing the functional hollow diameter without increasing the actual outer diameter of the speed reducer.
Solution Approach 2:
The patent employs an external tooth member that is eccentrically movable by the crank shafts, creating a dynamic carrier that rotates relative to the case. This dynamic structure allows for flexible cable routing and positioning, enabling multiple cables to pass through the hollow space efficiently while maintaining a compact overall size.
2Ease of operation
If the hollow diameter is increased to facilitate cable passage, then the ease of cable installation is improved, but the outer diameter of the speed reducer increases which contradicts the demand for reduced size
Solution Approach 1:
The patent implements a nested structure where the carrier with crank shafts is positioned inside the case, and the external tooth member is nested within the carrier. This nested arrangement maximizes the use of internal space, allowing cables to pass through the hollow space formed by the nested components without increasing the outer diameter of the entire speed reducer assembly.
Solution Approach 2:
By arranging crank shafts on a circumference and creating a rotating carrier structure, the patent utilizes three-dimensional space more effectively. This allows cables to pass through optimized paths within the nested structure, facilitating easy cable installation while maintaining a compact outer diameter.
3Strength
If the crank shafts are arranged on a larger imaginary circle to improve structural strength, then the strength is improved, but the hollow diameter decreases which contradicts the demand for increased hollow space
Solution Approach 1:
The patent optimizes the parameters by specifying that the imaginary circle diameter D2 satisfies the relation (D-D2)/(D2-R) ≥ 1.5, where D is the outer diameter and R is the inner diameter of the case. This parameter optimization allows the crank shafts to be positioned at an optimal radius that balances structural strength requirements with the need to maintain sufficient hollow diameter for cable passage.
Solution Approach 2:
The dynamic carrier structure allows the system to adapt its internal configuration, enabling the crank shafts to be arranged on an imaginary circle that optimizes both strength and hollow space. The rotating carrier creates flexible internal pathways that maintain structural integrity while preserving hollow diameter for cable routing.
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 design achieves a larger hollow diameter without increasing the speed reducer's size, preserving output and allowing for easier cable passage, while maintaining structural integrity and reduction ratio.
Implementation Method 1
an external tooth member having second external teeth meshing with the internal teeth of the case
Implementation Method 2
a plurality of crank shafts having a shaft axial line arranged on a circumference of an imaginary circle that is centered around the central axis of the case
Implementation Method 3
each crank shaft has first external teeth, an external tooth member having second external teeth meshing with the internal teeth of the case, where the external tooth member is eccentrically movable by the crank shafts
Data Source
AI summary
A speed reducer includes a case with internal teeth, where the case has a cylindrical shape and an outer diameter D, an inner cylinder centered around an central axis of the case and having an inner diameter R, where R/D falls within a range of 20% to 45%, crank shafts arranged on a circumference of an imaginary circle centered around the central axis of the case, where the crank shafts are spaced away from each other in a circumferential direction of the imaginary circle, and each crank shaft has first external teeth, an external tooth member having second external teeth meshing with the internal teeth, where the external tooth member is eccentrically movable by the crank shafts, and a carrier supporting the crank shafts in a rotatable manner, where the carrier is rotatable by the crank shafts relative to the case.