Workpiece Transfer Robot Joint Layout for High Torque and Low Height
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Solution Overview
Problem
Existing workpiece transfer robots face challenges with large vertical dimensions and insufficient torque due to the use of oscillating gear mechanisms and precession type speed reducers, which also complicate electrical wiring and piping within the robot joints.
Innovation Solution
A workpiece transfer robot design that incorporates a fixed gear, oscillating gear, and output gear arrangement around the output shaft, with a permanent magnet and electromagnet configuration that suppresses vertical dimension and allows for a hollow output shaft, enabling reduced weight and space for electrical wiring and piping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If an oscillating gear mechanism with coils is used to achieve large reduction ratio, then the reduction ratio is increased, but the vertical dimension becomes large
Solution Approach 1:
The patent repositions the oscillating gear mechanism from a vertical arrangement to a horizontal arrangement around the output shaft. The oscillating gear rotates horizontally in the internal space of the arm, with the fixed gear and output gear arranged radially around the output shaft, converting the vertical dimension problem into a radial space utilization solution.
Solution Approach 2:
The oscillating gear mechanism is nested within the internal space of the robot arm. The oscillating gear, fixed gear, and output gear are arranged in the radial direction within the hollow output shaft structure, efficiently utilizing the available internal volume without increasing the external vertical dimension.
2Ease of operation
If magnetic force from coils is used to drive the oscillating gear, then the oscillating gear can rotate, but the magnetic force is not strong enough under large load
Solution Approach 1:
The patent combines permanent magnets and electromagnets in a hybrid magnetic drive system. The permanent magnet provides a strong baseline magnetic field, while the electromagnet adds controllable magnetic force, creating a composite magnetic system that delivers sufficient driving force under large load conditions.
Solution Approach 2:
The patent merges the functions of permanent magnets and electromagnets into a single drive system. The permanent magnet establishes a persistent magnetic field, and the electromagnet modulates this field to control the oscillating gear's rotation, combining the advantages of both magnetic sources.
3Shape
If a precession type speed reducer is placed radially outside the motor rotor, then the actuator can be axially flattened, but the position of magnetic pole makes it difficult to generate torque
Solution Approach 1:
Instead of placing the speed reducer outside the motor rotor as in conventional designs, the patent inverts the arrangement by placing the oscillating gear mechanism inside the hollow output shaft. The motor rotor rotates at the center, and the speed reduction gears are nested within the rotor's internal space, reversing the traditional spatial relationship.
4Strength
If solid output shaft is used for structural strength, then the joint can support load, but electrical wiring and piping cannot be laid through the joint
Solution Approach 1:
The patent creates a hollow output shaft structure that nests electrical wiring and piping within its internal cavity. The oscillating gear mechanism is further nested within the hollow shaft space, creating a multi-level nested arrangement that accommodates both mechanical components and electrical infrastructure.
Solution Approach 2:
The output shaft is segmented into functional zones: the hollow internal space for wiring and piping, the radial space for gear mechanisms, and the external structure for load bearing. This segmentation allows each zone to fulfill its specific function without interfering with others.
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 large driving force while minimizing the vertical dimension of the robot joints, improving transport accuracy and reducing the weight of the arms, allowing for improved positioning and transport of workpieces.
Implementation Method 1
an electromagnet provided in an internal space of a front end of the second arm side and generating a rotating magnetic field with respect to the permanent magnet
Implementation Method 2
a bearing provided on an inner wall of the rotor, with an inclined central axis line inclined at a predetermined angle with respect to a central axis line as a center of rotation
Implementation Method 3
each tooth of the oscillating gear h on both sides meshes with the output gear f and the fixed gear g, thereby a rotor is configured so that the oscillating gear h is always inclined at a certain angle with respect to the output shaft e
Data Source
AI summary
A workpiece transfer robot has a joint equipped with a precise actuator that has a small size in the vertical direction. The actuator is configured from a speed reducer section arranged parallel to a circular fixed gear and a circular output gear. An oscillating gear is arranged inclined with respect to the fixed gear and the output gear between the fixed gear and the output gear. The fixed gear and the oscillating gear are configured to mesh at a first position, and the oscillating gear and the output gear are configured to mesh at a second position. In addition, a motor section drives the oscillating gear and is arranged coaxially with a permanent magnet on the outside of the oscillating gear, and the size of the joint of the workpiece transfer robot in the vertical direction is minimized by arranging an electromagnet coaxially on the outside of the permanent magnet.