Structured Gearwheel Web for Electric Drive Noise Reduction

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In electric vehicles, the lack of masking noise from internal combustion engines makes transmission noise a significant disturbance, and existing lightweight gearwheel designs struggle to balance low mass with high stiffness and durability, while also failing to effectively reduce structure-borne sound issues due to resonance-induced noise peaks.

Innovation Solution

A gearwheel design with a structured annular or corrugated web between the shaft seat and toothed ring, featuring non-uniform mass and stiffness distribution about the axis of rotation, achieved through varying apertures, ribs, or wavy structures, ensuring two-fold rotational symmetry to separate and distribute eigenmodes into different frequencies, thus reducing resonance-induced noise without introducing imbalance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If the gearwheel is designed with lightweight construction (reduced mass), then the mass is reduced, but the stiffness and durability are compromised

Engineering Contradiction:

Improvegearwheel massVSAvoidgearwheel stiffness and durability

Core Design Contradiction:

Weight of moving objectVSStrength

Solution Approach 1:

The gearwheel combines a metallic shaft seat and toothed ring with a plastic web structure, creating a composite construction that optimizes the balance between weight reduction and mechanical strength. The plastic material provides sufficient stiffness while being lighter than metal, resolving the contradiction between lightweight design and structural durability.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The gearwheel hub is divided into a metallic shaft seat, a plastic web with hole structure, and a metallic toothed ring. This segmentation allows each component to be optimized independently - the metal parts provide strength where needed, while the plastic web reduces overall mass, solving the weight-strength trade-off.

Inventive Principle:

Principle #1Segmentation

2Speed

If the gearwheel operates at high speeds with wide operating range, then the power transmission capability is improved, but the transmission noise increases due to resonance-induced noise peaks

Engineering Contradiction:

Improvegearwheel operating speedVSAvoidtransmission noise

Core Design Contradiction:

SpeedVSObject-generated harmful factors

Solution Approach 1:

The patent introduces non-uniform mass distribution through strategically placed holes and corrugated structures in the web, which modifies the natural frequencies of the gearwheel body. This parameter change shifts resonant frequencies away from operating ranges, reducing resonance-induced noise while maintaining high-speed operation capability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The web structure features localized variations in mass distribution with differently structured sectors containing varying numbers, positions, and sizes of holes. These local modifications create non-uniform mass distribution that effectively reduces structure-borne sound without compromising overall structural integrity or speed performance.

Inventive Principle:

Principle #3Local quality

3Object-generated harmful factors

If the web structure has non-uniform mass distribution, then the resonance-induced noise is reduced, but the gearwheel may become imbalanced

Engineering Contradiction:

Improvestructure-borne soundVSAvoidrotational balance

Core Design Contradiction:

Object-generated harmful factorsVSStability of the object's composition

Solution Approach 1:

The patent deliberately introduces asymmetric features (non-uniform hole distribution, corrugated structures) into the web to modify mass distribution and reduce resonance. This controlled asymmetry is designed to affect vibrational modes without creating harmful imbalances, resolving the contradiction between noise reduction and rotational stability.

Inventive Principle:

Principle #4Asymmetry

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 design effectively minimizes resonance-induced excessive noise, maintaining lightweight construction while ensuring the gearwheel meets durability and noise reduction criteria, by separating symmetrical eigenmodes into distinct frequencies, thereby reducing superposition and resonance peaks.

Implementation Method 1

the NVH behavior (noise vibration harshness) in the individual transmission stages is caused in particular by noise peak levels of wheel body resonant vibrations

Methodology Applied

Scientific EffectResonance: Resonance

Implementation Method 2

separating symmetrical eigenmodes into distinct frequencies, reducing superposition and resonance peaks

Methodology Applied

Scientific EffectVibration: Vibration

Data Source

PatentUS11867272B2Gearwheel for reducing structure-borne sound in electric drives

Publication Date: 2024.01.09 ZF FRIEDRICHSHAFEN AG

AI summary

Gearwheel for structure-borne sound reduction in electric drives, having a toothed ring and a wheel hub, which has a structured annular or corrugated web between a shaft seat and the toothed ring. The web has a structure designed with deviations from uniform stiffness and mass distribution about an axis of rotation of the gearwheel, and has an axial symmetry to avoid imbalance. The gearwheel has a two-fold, four-fold, six-fold or eight-fold cyclic axial symmetry.