Robot Drive Unit Oil Absorber With Cellulose Fiber Retention

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Solution Overview

Problem

Existing oil absorbers for robot driving units have insufficient oil-component absorbing characteristics, leading to difficulty in spreading and retaining oil, with a risk of leakage to the outside.

Innovation Solution

An oil absorber composed of defibrated cellulose fibers bound by a thermoplastic resin, which quickly absorbs and spreads oil components, retaining them effectively despite mechanical stress and vibrations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a porous body such as a sponge is used as an oil absorber, then the oil absorber can absorb oil components, but the oil component cannot spread effectively and retention is weak leading to leakage

Engineering Contradiction:
Improveoil component absorption capacityVSAvoidoil retention capability
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The invention uses a composite material consisting of cellulose fibers and a binding material. The cellulose fibers provide oil absorption capacity through their hydrophilic nature and porous structure, while the binding material holds the fibers together to form a stable sheet structure that prevents oil leakage. This composite structure resolves the contradiction between absorption capacity and retention reliability.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The oil absorber is constructed with cellulose fibers that form a porous network structure. These pores allow oil components to penetrate and be absorbed effectively. The porous structure of cellulose fibers provides high surface area for oil contact while maintaining structural integrity through the binding material, thus achieving both absorption and retention.

Inventive Principle:
Principle #31Porous materials

2Quantity of substance

If grease is contained in a circular recess with a felt member, then grease can be contained, but oil-component spreading and retention remains insufficient

Engineering Contradiction:
Improvegrease containmentVSAvoidoil-component retention
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The invention replaces the traditional felt member with a composite sheet structure made of cellulose fibers and binding material. This composite material provides superior oil-component retention through the synergistic effect of hydrophilic cellulose fibers and the structural stability provided by the binding material, preventing leakage that occurs with traditional felt members.

Inventive Principle:
Principle #40Composite materials

3Ease of manufacture

If a traditional oil absorber structure is used, then it can be manufactured simply, but it has insufficient oil-component absorbing characteristics and weak retention power

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidoil-component absorption efficiency
Core Design Contradiction:
Ease of manufactureVSQuantity of substance

Solution Approach 1:

The invention changes the material parameters by using cellulose fibers with specific properties (hydrophilic nature, porous structure) combined with a binding material. This parameter change in material composition enables high oil-component absorption efficiency while maintaining ease of manufacture through sheet formation processes.

Inventive Principle:
Principle #35Parameter changes

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 oil absorber efficiently absorbs and retains oil components, preventing leakage by spreading them over a wide area and maintaining retention under operational conditions.

Implementation Method 1

an oil absorber (1) comprising: defibrated material (10), and a binding material (20)

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Data Source

PatentEP4421354B1Oil absorber
Publication Date: 2025.10.29 SEIKO EPSON CORP
  • EP4421354B1 patent drawingFigure 1~2
  • EP4421354B1 patent drawingFigure 3
  • EP4421354B1 patent drawingFigure 4

AI summary

An oil absorber is disposed around a rotational driving unit of a robot and absorbs an oil component. The oil absorber includes a defibrated material obtained by defibrating fibers, and a binding material that binds the fibers together. The rotational driving unit includes a motor and a speed reducer coupled to one end portion of the motor. The oil absorber is disposed at least at one of an outer circumferential portion of the speed reducer, surroundings around the motor, and the other end portion of the motor.