Rotary Joint Cable Cassette for Strain-Free Motion

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Solution Overview

Problem

Conventional cable management systems in rotary joints fail to adequately protect conductors from mechanical strain, electromagnetic interference, and physical damage in harsh environments, leading to premature failure and performance issues.

Innovation Solution

A cable management system featuring a rotary housing with a cable cassette that winds cables around a guide as the joint rotates, minimizing mechanical stress and providing internal shielding, while allowing a larger range of motion in a smaller package.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If cables are packaged externally with a large joint loop to accommodate the entire range of motion, then the cables can move freely with the joint, but this creates a snagging hazard and kinematic constraints

Engineering Contradiction:
Improverange of motionVSAvoidsnagging hazard
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The cable management system nests the cable reel inside a protective housing, with the cable wound around the reel in a compact configuration. This nested structure allows the joint to achieve a large range of motion while the cable remains contained, eliminating the external loop that causes snagging hazards.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

Instead of allowing the cable to form a large external loop in three-dimensional space, the system winds the cable around a reel, transforming the cable's path into a compact two-dimensional spiral pattern on the reel surface. This dimensional transformation reduces the spatial footprint and eliminates snagging hazards while maintaining range of motion.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Ease of operation

If cables are subject to external mechanical loading from rotating joint, then the joint can rotate, but the conductors in the cable may break due to tension, bending strain, or fatigue

Engineering Contradiction:
Improvejoint rotationVSAvoidconductor integrity
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The cable reel acts as an intermediary mechanism between the rotating joint and the cable conductors. As the joint rotates, the reel winds or unwinds the cable, mediating the mechanical motion and preventing direct tension and bending strains from being applied to the conductors. This protects the conductors from fatigue and breakage while enabling joint rotation.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system provides beforehand cushioning by maintaining proper cable tension and routing through the reel mechanism, preventing excessive bending strains and mechanical loads from reaching the conductors before they can cause damage. The reel ensures the cable is always properly supported and routed, cushioning the conductors against harmful mechanical stresses.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Strength

If the cable bundle is made stiff to support mechanical loads, then the conductors are protected, but the stiffness affects performance of the joint

Engineering Contradiction:
Improvemechanical supportVSAvoidjoint performance
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The cable reel serves as an intermediary that assumes the mechanical support function, allowing the cable bundle to remain flexible for optimal joint performance while the reel provides the necessary mechanical strength and load-bearing capability through its winding mechanism.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP4576462A1Cable management system and methods for a rotary joint
Publication Date: 2025.06.25 MACDONALD DETTWILER & ASSOC INC
  • EP4576462A1 patent drawingFigure 1
  • EP4576462A1 patent drawingFigure 2A~2B
  • EP4576462A1 patent drawingFigure 3A

AI summary

Provided is a system for cable management in a rotary joint. The system includes a rotary housing that rotates about a rotational axis relative to a stationary housing. The stationary housing has a stationary cavity for allowing a cable to pass through. The system includes a cable management system for managing one or more cables. The cable management system includes a cable cassette attached to the stationary housing, wherein the cable cassette winds the cable around the cable cassette as the rotary joint rotates.