Coupling Rod Mechanical Low-Pass Filter for Vibration Isolation

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Solution Overview

Problem

Existing driven axle designs, particularly for two-track vehicles, fail to effectively mitigate dynamic longitudinal vibrations caused by reciprocating internal combustion engines, leading to discomfort and noise due to unaddressed natural vibrations of the vehicle drive unit.

Innovation Solution

Incorporating a mechanical low-pass filter in the coupling rod or its connection to the links, which reduces rigidity in low-frequency ranges to cancel cornering forces while blocking higher-frequency disruptive forces, allowing the coupling rod to transmit these forces between the left and right wheels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the coupling rod is made rigid to transmit cornering forces effectively, then cornering stability is improved, but high-frequency vibrations from the drive unit are transmitted to the vehicle body

Engineering Contradiction:
Improvecornering stabilityVSAvoidvibration transmission
Core Design Contradiction:
Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The coupling rod incorporates a mechanical low-pass filter that dynamically adjusts its characteristics based on frequency. The filter allows rigid coupling for low-frequency cornering forces while providing vibration isolation for high-frequency drive unit disturbances, transforming the static rigid structure into a dynamic adaptive system.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The mechanical low-pass filter changes the effective stiffness parameter of the coupling rod based on frequency. At low frequencies (cornering), the rod maintains high stiffness for stability, while at high frequencies (vibrations), the effective stiffness is reduced to block vibration transmission, achieving both cornering stability and vibration reduction.

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If additional absorber masses are added to mitigate longitudinal vibrations, then vibration mitigation is improved, but device complexity increases

Engineering Contradiction:
Improvelongitudinal vibration mitigationVSAvoidsuspension system complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The mechanical low-pass filter integrated into the coupling rod serves multiple functions simultaneously: it maintains cornering stability through rigid coupling, blocks high-frequency vibration transmission, and mitigates longitudinal vibrations from the drive unit. This multi-functional approach eliminates the need for separate absorber masses and complex suspension coordination systems.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The vibration mitigation function is merged into the existing coupling rod structure through the integrated mechanical low-pass filter. Instead of adding separate absorber masses and complex coordination mechanisms, the filter combines cornering force transmission and vibration mitigation into a single component, reducing overall system complexity.

Inventive Principle:
Principle #5Merging (Combining)

3Stability of the object's composition

If the coupling rod transmits all forces between left and right wheels, then wheel synchronization is improved, but disruptive forces from drive unit irregularities are amplified

Engineering Contradiction:
Improvewheel synchronizationVSAvoiddisruptive force amplification
Core Design Contradiction:
Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

The mechanical low-pass filter provides dynamic force transmission characteristics, allowing synchronous wheel movement for steady-state cornering forces while dynamically blocking disruptive forces from drive unit irregularities. This creates an adaptive coupling that responds differently to various force types based on their frequency content.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The coupling rod exhibits different mechanical properties for different force components: it provides rigid coupling for low-frequency cornering forces to maintain wheel synchronization, while providing vibration isolation for high-frequency disruptive forces. This local differentiation of mechanical quality allows simultaneous achievement of synchronization and disturbance rejection.

Inventive Principle:
Principle #3Local quality

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 cancels out disruptive forces introduced by rotational irregularities of the drive unit, improving vehicle comfort and reducing noise by converting longitudinal vibrations into transverse vibrations that counteract each other, thereby enhancing driving dynamics and acoustics.

Implementation Method 1

a mechanical low-pass filter is provided in the coupling rod and/or in the connection between the coupling rod and one of the links supported against one another by this, which filter reduces the rigidity of the coupling rod in low frequency ranges

Methodology Applied
Scientific EffectMechanical low-pass filter:

Implementation Method 2

the coupling rod then transmits these disturbing forces between the left-hand handlebar and right-hand handlebar

Methodology Applied
Scientific EffectForce transmission:

Data Source

PatentEP2874832B1Driven axle of a dual-track vehicle
Publication Date: 2018.10.31 BAYERISCHE MOTOREN WERKE AG
  • EP2874832B1 patent drawingFigure 1

AI summary

A driven axle of a dual-track vehicle is provided in which a wheel-guiding control rod on the body of the vehicle or on a cross member connected to the body of the vehicle is stabilized spatially in an slightly elastic fashion via a control rod bearing on the body. The control rod of the right-hand wheel is additionally connected to the control rod of the left-hand wheel via a coupling rod. The coupling rod is exclusively supported on the left-hand and right-hand control rod, preferably in the vicinity of the respective control rod bearing on the body of the vehicle that is disposed in an offset fashion in the longitudinal direction of the vehicle relative to the associated wheel bearing. A mechanical deep-pass filter is provided in the coupling rod and/or in the connection between the coupling rod and a control rod stabilized relative thereto.