Laundry Motor Rotor Frequency Tuning to Avoid Resonance

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Laundry appliance electric motors often produce excessive noise due to natural resonating frequencies during operation, which existing technologies have not effectively addressed.

Innovation Solution

The implementation of a harmonic-modulating member, such as a metallic reinforcing plate or inertial rings, attached to the rotor of the electric motor to modulate the baseline natural frequency, shifting it to a modulated frequency that falls outside the operational range, thereby reducing noise production.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the rotor operates at high rotational speeds to improve productivity, then the motor output increases, but noise and vibration increase due to natural resonating frequencies

Engineering Contradiction:

Improvemotor rotational speedVSAvoidnoise and vibration

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent applies parameter changes by modifying the natural frequency of the rotor through the addition of a harmonic modulating member. This member alters the mass distribution and stiffness characteristics of the rotor, thereby changing its natural frequency parameters to avoid resonance with operational frequencies, reducing noise and vibration while maintaining high rotational speed

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the harmful resonance phenomenon into a beneficial outcome by strategically positioning the harmonic modulating member to shift the natural frequency away from operational ranges. The same structural modifications that could potentially increase mass or complexity are used to eliminate the harmful resonance effect, turning what could be a disadvantage into a noise-reduction solution

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Object-generated harmful factors

If a harmonic-modulating member is added to the rotor to reduce noise, then noise and vibration decrease, but the device complexity increases

Engineering Contradiction:

Improvenoise and vibrationVSAvoid rotor structure

Core Design Contradiction:

Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The patent applies local quality by adding the harmonic modulating member only at specific locations on the rotor where it most effectively influences the natural frequency. Rather than modifying the entire rotor structure, the solution focuses on localized additions (such as rings or plates at specific radial positions) that achieve the frequency modulation goal with minimal structural complexity

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs composite structural concepts by combining the original rotor structure with the harmonic modulating member. This creates a composite rotor system where the modulating member (potentially made of different materials or structural configurations) works in conjunction with the base rotor to achieve the desired frequency characteristics without completely redesigning the entire rotor

Inventive Principle:

Principle #40Composite materials

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 solution effectively minimizes noise and vibration by altering the natural harmonic frequency of the rotor, ensuring the motor operates without significant harmonic disturbance, even at high rotational speeds.

Implementation Method 1

A harmonic-modulating member is attached to the rotor that modulates the baseline excitation frequency of the rotor to be a modulated natural frequency. The predetermined range of rotational frequencies is free of the modulated natural frequency of the rotor.

Methodology Applied

Scientific EffectNatural frequency modulation: Resonance

Data Source

PatentUS10910910B2Acoustical treatment for a rotor of a laundry appliance

Publication Date: 2021.02.02 WHIRLPOOL CORP

AI summary

A drive motor for a laundry appliance includes a stator having a plurality of windings that extend around teeth of the stator. A rotor is in electromagnetic communication with the stator. The rotor is coupled to a drive shaft that extends through the stator. When the winding of the stator is electrically energized, the rotor rotates relative to the stator at a predetermined range of rotational frequencies that includes a baseline natural frequency of the rotor. A harmonic-modulating member is attached to the rotor that modulates the baseline natural frequency of the rotor to be a modulated natural frequency. The predetermined range of rotational frequencies is free of the modulated natural frequency of the rotor.