Robot Joint Structure With Preloaded Bevel Gear Engagement

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing manipulator devices experience wobbling or rattling due to axial thrust on bevel gears, leading to loose engagement and potential mechanical instability.

Innovation Solution

A joint structure for a robot that includes a first link and a second link rotatably coupled via a joint part, with a first actuator and a second actuator, and a shaft member with shanks oriented in different directions, using a pressing member to press second rotary members inwardly via rotary transmitting members to suppress or eliminate wobbling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If bevel gears are used for differential motion transmission, then torque transmission capability is improved, but axial thrust causes loose engagement and wobbles

Engineering Contradiction:
Improvetorque transmission capabilityVSAvoidengagement stability
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The pressing member applies preliminary axial force to the second rotary member before operation, pre-compressing the bevel gear engagement to counteract the loosening effect of axial thrust during operation, thereby preventing wobbles and maintaining reliable engagement

Inventive Principle:
Principle #9Preliminary anti-action

Solution Approach 2:

The pressing member is positioned and adjusted beforehand to establish optimal pre-load on the second rotary member, ensuring that the bevel gears maintain tight engagement throughout the operational range without requiring continuous adjustment

Inventive Principle:
Principle #10Preliminary action

2Reliability

If pressing member is added to suppress wobbles, then engagement stability is improved, but device complexity increases

Engineering Contradiction:
Improveengagement stabilityVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The pressing member is integrated with the existing shaft member structure, serving both as a positioning element and a pressing mechanism, thereby suppressing wobbles without requiring a completely separate complex assembly

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The pressing member is nested within the existing shaft member and bearing structure, utilizing the available space and structural elements to achieve the pressing function without adding external complexity to the overall mechanism

Inventive Principle:
Principle #7Nested doll (Nesting)

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 joint structure effectively suppresses or eliminates wobbling, enhances rigidity, reduces the need for precise sensors, and lowers costs by ensuring secure engagement and efficient operation.

Implementation Method 1

a pressing member connected to the second shank and configured to press the second rotary member inwardly

Methodology Applied
Scientific EffectMechanical Force: Mechanical Force

Data Source

PatentEP4026670B1Robot joint structure
Publication Date: 2025.11.19 KAWASAKI JUKOGYO KK
  • EP4026670B1 patent drawingFigure 1
  • EP4026670B1 patent drawingFigure 2

AI summary

A joint structure for a robot according to the present disclosure includes a first link (10) and a second link (20) rotatably coupled to each other via a joint part (40). The joint part (40) has a first rotary member (41) disposed so that an axial center thereof is oriented in a first direction and connected to the first link (10), a pair of second rotary members (42A, 42B) disposed so that an axial center thereof is oriented in a second direction perpendicular to the first direction, and so as to engage with the first rotary member (41), and a shaft member (1) formed in a T-shape and having a first shank (11) and a pair of second shanks (12A, 12B). The joint structure further includes a pressing member connected to the second shank and configured to press the second rotary member inwardly.