Reducing cleaning roller amplitude and speed oscillations of a cleaning robot

Solution Overview

Problem

In robotic vacuum cleaners, the cleaning roller's rotational speed can fluctuate due to pinching between the floor and a bushing shroud, leading to decreased and increased speed episodes, which causes wear and noise.

Innovation Solution

A bushing shroud with a reduced cross-section is used to provide additional compliance at the bearing end of the cleaning roller, allowing it to deflect radially inward and reducing the likelihood of pinching, while maintaining protection against hair migration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a standard cross-section bushing shroud is used, then protection against hair migration is provided, but the cleaning roller experiences pinching between the floor and bushing shroud causing rotational speed fluctuations

Engineering Contradiction:

Improverotational speed stabilityVSAvoidpinching and wind-up issues

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The bushing shroud cross-sectional dimensions are reduced from standard specifications to create additional compliance and radial deflection capability. This parameter change allows the bushing shroud to accommodate floor variations without pinching the cleaning roller shell, eliminating rotational speed fluctuations while maintaining the protective function against hair migration.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The bushing shroud is designed with non-uniform cross-sectional dimensions, creating localized compliance zones at critical areas where pinching occurs. The reduced cross-section is specifically positioned at the bearing end to provide radial deflection capability where needed, while maintaining adequate protection in other regions.

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If the bushing shroud cross-section is reduced to provide compliance, then pinching is reduced, but protection against hair migration may be compromised

Engineering Contradiction:

Improvepinching and rotational speed fluctuationsVSAvoidprotection against hair migration

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The bushing shroud is designed with non-uniform cross-sectional dimensions, creating localized compliance zones at critical areas where pinching occurs. The reduced cross-section is specifically positioned at the bearing end to provide radial deflection capability where needed, while maintaining adequate protection in other regions.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The bushing shroud cross-sectional dimensions are reduced from standard specifications to create additional compliance and radial deflection capability. This parameter change allows the bushing shroud to accommodate floor variations without pinching the cleaning roller shell, eliminating rotational speed fluctuations while maintaining the protective function against hair migration.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the cleaning roller shell is made more compliant to prevent pinching, then rotational speed stability improves, but structural strength may be reduced

Engineering Contradiction:

Improverotational speed stabilityVSAvoidshell structural strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

Instead of changing the shell material or structure, the invention modifies the bushing shroud cross-sectional dimensions to create compliance. This approach achieves rotational speed stability while preserving the shell's structural strength and integrity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The bushing shroud acts as an intermediary element between the cleaning roller shell and the floor. By reducing its cross-section, it provides a compliant interface that absorbs variations in floor height and prevents direct pinching forces from being transmitted to the shell, thereby maintaining both stability and strength.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

This configuration stabilizes the rotational speed of the cleaning roller, reducing wear and noise, and improving debris pickup efficiency by preventing pinching and wind-up issues.

Implementation Method 1

providing a bushing shroud having a reduced cross section in one or more portions, such as to provide additional compliance in the bearing end of the cleaning roller

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS11678780B2Reducing cleaning roller amplitude and speed oscillations of a cleaning robot

Publication Date: 2023.06.20 IROBOT CORP

AI summary

A roller assembly for a mobile cleaning system for cleaning a work surface can include a drive shaft, a sheath, a bushing, and a bushing shroud. The drive shaft can be rotatable about a drive axis, and the drive shaft can include a driven end and an opposite bushing end. The sheath can be supported by the drive shaft and the sheath can be rotatable with the drive shaft. The sheath can include a shell engageable with the work surface. The bushing can be located about the bushing end of the drive shaft. The bushing shroud can be connected to the bushing. The sheath and the drive shaft can be together rotatable with respect to the bushing and the bushing shroud, the bushing shroud can include an outer portion defining a first radius of curvature and a recessed portion connected to the outer portion.