Narrow Robot Joint Axis With Direct Drive and Nested Brake Seal

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Solution Overview

Problem

Conventional vertical articulated robots with motors and speed reducers connected via timing belts face reduced positioning accuracy due to belt stretching, and direct connection increases the joint axis size, making it difficult to downsize the robot.

Innovation Solution

The design includes a narrow joint axis portion with a motor, speed reducer, brake, and oil seal, where at least one of the brake or oil seal is arranged inside a recess within the speed reducer, allowing direct connection without a timing belt and reducing the axial size of the joint axis portion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the motor and speed reducer are connected via a timing belt, then the positioning accuracy is maintained, but the joint axis size increases and the robot cannot enter narrow spaces

Engineering Contradiction:

Improvepositioning accuracyVSAvoidjoint axis size

Core Design Contradiction:

Measurement precisionVSVolume of moving object

Solution Approach 1:

The timing belt connection is extracted and removed from the system. Instead of using a timing belt to connect the motor and speed reducer, the patent implements a direct connection, thereby eliminating the space occupied by the timing belt and its tensioning mechanism, which allows the joint axis to be downsized.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The motor and speed reducer are merged into a more compact integrated unit by eliminating the timing belt connection. The direct connection allows these components to be positioned closer together and share common structural elements, reducing the overall joint axis size.

Inventive Principle:

Principle #5Merging (Combining)

2Volume of moving object

If the motor and speed reducer are directly connected, then the joint axis size is reduced, but the positioning accuracy decreases due to timing belt stretching

Engineering Contradiction:

Improvejoint axis sizeVSAvoidpositioning accuracy

Core Design Contradiction:

Volume of moving objectVSMeasurement precision

Solution Approach 1:

The mechanical timing belt transmission system is replaced with a direct mechanical connection. This substitution eliminates the timing belt stretching issue that causes positioning accuracy degradation, while achieving the desired compact joint axis size.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If the brake and oil seal are arranged outside the speed reducer, then the assembly is simpler, but the axial size of the joint axis portion increases

Engineering Contradiction:

Improveassembly simplicityVSAvoidaxial size of joint axis portion

Core Design Contradiction:

Ease of manufactureVSLength of stationary object

Solution Approach 1:

The brake and oil seal are nested inside the speed reducer housing rather than being arranged externally. This nesting arrangement allows these components to occupy the internal space of the speed reducer, thereby reducing the axial length of the joint axis portion without significantly complicating the assembly process.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

Instead of arranging the brake and oil seal in the axial direction (outside the speed reducer), the patent repositions them in the radial direction (inside the speed reducer housing). This dimensional change reduces the axial size of the joint axis portion while maintaining assembly feasibility.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS11865710B2Vertical articulated robot, single-axis robot, and motor unit

Publication Date: 2024.01.09 YAMAHA MOTOR CO LTD

AI summary

A vertical articulated robot includes a plurality of joint axis portions configured to rotationally drive a plurality of arms. The plurality of joint axis portions include a narrow joint axis portion. In the narrow joint axis portion, at least one of at least a portion of a brake or an oil seal is arranged inside a recess.