Industrial Robot Wrist Driving Structure with Hypoid Gear Sets
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Solution Overview
Problem
Existing wrist driving structures for industrial robots are bulky and heavy due to complex gear systems, limiting their compactness and increasing moment of inertia, which hinders their use in narrow spaces and reduces productivity in production lines.
Innovation Solution
A wrist driving structure with two servo motors and hypoid gear sets, where the driven ring gears are coaxial and the driving gears are positioned parallel to each other, minimizing space and cross-sectional area, allowing for a more compact design and improved control responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If complex gear systems with multiple stages are used to achieve large reduction ratios, then the reduction ratio is improved, but the device complexity and size increase
Solution Approach 1:
The patent combines multiple gear functions into integrated hypoid gear sets that achieve large reduction ratios in a single stage. The hypoid gears integrate the functions of speed reduction and torque multiplication in one compact assembly, eliminating the need for separate gear stages and reducing overall system complexity while maintaining high power transmission capability.
Solution Approach 2:
The patent utilizes the three-dimensional arrangement of hypoid gears with offset axes to achieve compact packaging. By positioning the gear axes in different spatial dimensions rather than linear sequences, the design achieves high reduction ratios without extending the robot arm length, thus reducing device complexity in the critical directional dimensions.
2Power
If complex gear systems with multiple stages are used to achieve large reduction ratios, then the reduction ratio is improved, but the wrist element size increases
Solution Approach 1:
The patent merges multiple gear stages into single-stage hypoid gear sets that achieve equivalent reduction ratios. This consolidation reduces the cumulative volume of gear components while maintaining the required power transmission, directly decreasing wrist element size without sacrificing reduction capability.
Solution Approach 2:
The patent arranges hypoid gear axes in three-dimensional space with strategic offsets, allowing compact packaging of the gear system. This spatial arrangement achieves high reduction ratios within a reduced volume by utilizing vertical and lateral dimensions rather than extending the arm linearly.
3Power
If complex gear systems with multiple stages are used to achieve large reduction ratios, then the reduction ratio is improved, but the weight increases
Solution Approach 1:
The patent consolidates multiple gear stages into fewer, more efficient hypoid gear sets. The single-stage hypoid design reduces the total weight of gear components by eliminating redundant stages while maintaining equivalent reduction ratios through optimized gear geometry and direct-drive architecture.
Solution Approach 2:
The patent replaces traditional multi-stage mechanical gear trains with hypoid gear sets that utilize optimized contact mechanics and direct drive paths. This substitution reduces the number of mechanical components and their associated weights while achieving the same power transmission through improved mechanical efficiency.
4Power
If the wrist element is made heavier to accommodate complex gear systems, then the reduction ratio is improved, but the moment of inertia increases
Solution Approach 1:
The patent merges gear functions into compact hypoid gear sets positioned close to the motor and wrist joints. This consolidation reduces the moment of inertia by minimizing the radius of gyration of the gear system, allowing faster acceleration and deceleration of the wrist element without sacrificing reduction ratio capability.
Solution Approach 2:
The patent positions hypoid gear axes in three-dimensional arrangements that minimize the radial distance from the rotation center. This spatial optimization reduces the moment of inertia by concentrating the gear mass closer to the joint axis, enabling improved dynamic response while maintaining high reduction ratios.
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 enables the wrist element to be more compact, reducing interference in narrow spaces and allowing for increased robot density in production lines, enhancing productivity while maintaining efficient power transmission and control.
Implementation Method 1
two gear sets for reducing a rotational speed of the two driving motors in predetermined reduction ratios; wherein each of the two gear sets comprises a driving gear driven by one of the driving motor and a driven ring gear which meshes with the driving gear
Implementation Method 2
the two driven ring gears are disposed coaxially with the second axis, and wherein the two driving gears are positioned parallel to each other at both sides of the plane containing said first axis and said second axis
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A wrist driving structure for an industrial robot having: a first wrist element (10,10A,10B) supported in cantilever fashion rotatably about a first axis (a); a second wrist element (11) pivotally supported in cantilever fashion at a distal end side of the first wrist element with a proximal end as a supporting point about a second axis (b) intersecting the first axis; a third wrist element (12) supported in cantilever fashion at a distal end side of the second wrist element rotatably about a third axis (c) intersecting the second axis; two driving motors (13,14) provided in the first wrist element for driving the second wrist element and the third wrist element, respectively; and two gear sets (15,20) for reducing a rotational speed of the two driving motors in predetermined reduction ratios. Each of the gear sets has a driving gear (16,21) driven by one of the two driving motors and a driven ring gear (17,22) which meshes with the driving gear. Two driven ring gears of the two gear sets are disposed coaxially with the second axis. Two driving gears of the two gear sets are positioned parallel to each other at both sides of the second axis.