Robot Joint Brake Assembly With Adjustable Friction Tension

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Solution Overview

Problem

Existing brake assemblies for collaborative robots face challenges in providing reliable, safe, and cost-effective braking solutions due to manufacturing tolerances and difficulties in achieving precise brake friction during assembly.

Innovation Solution

An annular brake member with a resilient member and positionable locking members arranged on the motor axle, allowing for adjustable friction by varying the tension of the resilient member, which is applied between the annular brake member and locking members, enabling precise control of brake friction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a brake assembly is designed with fixed components and standard manufacturing tolerances, then the device complexity is reduced and ease of manufacture is improved, but the manufacturing precision of brake friction is insufficient and reliability is compromised

Engineering Contradiction:
Improvebrake friction precisionVSAvoidbrake assembly structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The brake assembly incorporates an adjustable resilient member (spring) that allows dynamic adjustment of brake friction force. The spring can be compressed to different degrees to vary the pressing force on the brake member, enabling precise control of friction without requiring complex fixed structures. This transforms a static brake system into a dynamically adjustable one, resolving the contradiction between precision and complexity.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention changes the physical parameter of spring compression distance to control brake friction. By adjusting how much the resilient member is compressed between the first and second locking members, the pressing force and consequently the friction can be precisely tuned. This parameter-based adjustment mechanism provides manufacturing precision without increasing overall device complexity.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the brake assembly uses a resilient member with adjustable tension, then the reliability and precision of brake friction are improved, but the ease of manufacture deteriorates due to additional adjustment requirements

Engineering Contradiction:
Improvebrake operation safetyVSAvoidassembly process
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The brake assembly is segmented into distinct functional components: the resilient member, the brake member, and the two locking members. This segmentation allows each component to be manufactured separately using standard processes, then assembled together. The adjustment mechanism is divided into discrete elements that can be independently manufactured and positioned, making the overall assembly easier to manufacture despite the adjustable feature.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The locking members serve as intermediary elements that mediate between the resilient member and the brake member. These locking members provide a standardized interface for adjusting spring tension while maintaining simple manufacturing requirements. The intermediaries enable reliable force transmission and adjustment without requiring complex direct connections, thus improving reliability while preserving ease of manufacture.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If the brake member is designed to prevent rotation effectively, then the safety and reliability are improved, but the wear on gear systems increases due to excessive friction

Engineering Contradiction:
Improvemotor axle braking reliabilityVSAvoidgear system wear
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The invention uses adjustable spring compression as a parameter control mechanism to optimize brake friction force. By precisely controlling the compression distance of the resilient member, the pressing force on the brake member can be tuned to provide sufficient braking reliability while avoiding excessive friction that would cause gear wear. This parameter optimization resolves the contradiction between reliable braking and reduced wear.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The brake assembly applies partial braking force through the adjustable resilient member rather than maximum friction at all times. The spring can be compressed to provide just enough braking force for safe operation, avoiding excessive friction. This partial action approach ensures reliability when needed while minimizing harmful wear during normal operation.

Inventive Principle:
Principle #16Partial or excessive action

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 solution allows for precise adjustment of brake friction, ensuring safe and reliable operation of collaborative robots by preventing motor axle rotation while allowing for manual rotation when engaged, thus enhancing safety and reducing wear on gear systems.

Implementation Method 1

The resilient member 135 is provided at the motor axle and the resilient member 135 is provided as annular leaf spring arranged at the motor axle

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

a brake assembly configured as a friction brake which can activated and deactivated and provide controlled braking of the output flange

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3793787B1Robot joint comprising brake assembly
Publication Date: 2023.11.15 UNIVERSAL ROBOTS AS DK
  • EP3793787B1 patent drawingFigure 1a~1b
  • EP3793787B1 patent drawingFigure 2
  • EP3793787B1 patent drawingFigure 3~5

AI summary

A robot joint connectable to at least another robot joint via an output flange. The robot joint comprises a joint motor having a motor axle configured to rotate the output flange. The robot joint comprises a brake assembly comprising an annular brake member rotatable and a resilient member arranged on the motor axle. The annular brake member and the resilient member are arranged between a first locking member and a positionable locking member, where the positionable locking member can be fixed at a plurality of positions along and at the motor axle. An engagement member is movable between an engaging position and a non-engaging position, where in the engaging position the engagement member engages with the annular brake member and prevents rotation of the annual brake member around the motor axis. The annular may comprise brake protrusion comprises two slats forming a triangular like shape.