Fan Drive Damping System for Axial Play Noise Reduction
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Solution Overview
Problem
Electric motor drives in motor vehicles experience unwanted noise due to axial play of the motor shaft, leading to impact and vibration noises, which are exacerbated by resonance phenomena and the interaction between the commutator and fan wheel.
Innovation Solution
A damping system is implemented on both sides of the shaft bearings, comprising a sealing disk, sliding disk, and a ring-shaped damping element, with a spring deflection and a thermoplastic elastomer shaft seal, to absorb axial play and reduce noise transmission through the motor housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a damping system is added to reduce noise from axial play, then noise level is reduced, but device complexity increases
Solution Approach 1:
The patent combines multiple functions into a single integrated damping system assembly that includes the sealing disk, damping element, and sliding disk working together. This merging approach reduces the need for separate components while achieving both noise reduction and axial play compensation, thereby limiting the increase in device complexity.
Solution Approach 2:
The damping system is designed to perform multiple functions simultaneously: it dampens impact noises from axial play, reduces structure-borne noise from commutator-brush interactions, and compensates for axial shaft deflections. This multi-functionality allows a single system to address multiple noise sources without proportionally increasing complexity.
2Object-generated harmful factors
If damping elements are added to absorb vibrations, then vibration noise is reduced, but manufacturing complexity increases
Solution Approach 1:
The damping element is positioned specifically at the damping system location where axial play and vibrations occur, rather than distributing damping throughout the entire motor. This localized approach concentrates the vibration absorption function where it is most needed, simplifying manufacturing compared to widespread damping implementation.
Solution Approach 2:
The patent employs a damping element made of viscoelastic material that combines properties of both flexibility and energy absorption. This composite material approach allows the damping function to be achieved through material selection rather than complex mechanical structures, thereby reducing manufacturing complexity.
3Object-generated harmful factors
If the damping system compensates for axial play, then impact noises are reduced, but the shaft bearing load increases
Solution Approach 1:
The damping element is positioned to provide cushioning before axial impacts occur, absorbing the energy of axial play deflections in advance. This beforehand cushioning prevents impact noises from reaching the shaft bearing, thereby reducing the bearing load from impact forces while still compensating for axial play.
Solution Approach 2:
The damping system acts as an intermediary between the axial play source and the shaft bearing, absorbing and dampening vibrations before they transmit to the bearing. This intermediary function reduces the force transmitted to the bearing while maintaining axial play compensation.
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 damping system significantly reduces structure-borne noise and U-tones by absorbing axial deflections and vibrations, thereby minimizing sound levels across the speed range of the electric motor, particularly at resonance frequencies.
Implementation Method 1
a spring deflection is suitably defined between the sealing disk and the sliding disk, which is expediently in the tenth of a millimeter range and is preferably less than or equal to 0.2 mm. Between the sealing disk and the sliding disk, a spring ring-like corrugated spring placed on the motor shaft is used as the preferred spring element.
Implementation Method 2
a spring ring-like corrugated spring placed on the motor shaft is used as the preferred spring element. As is known, this corrugated spring contributes significantly or even essentially to the damping of the howling or U-tones.
Implementation Method 3
The sealing disk, the damping element and the shaft seal are preferably produced in one piece from a two-component plastic using the injection molding process. A thermoplastic elastomer is particularly suitable as the damping material.
Data Source
Figure 1
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AI summary
In an electro-motor drive, in particular for a fan drive of a motor vehicle, comprising a commutator motor (1), the motor shaft (4) of which is rotatably mounted on axially opposing sides (BS, AS) in shaft bearings (9, 10) covered by means of a bearing shield (7, 8), a damping system (14) is arranged on the bearing side of the or each shaft bearing (9, 10) facing away from the bearing shield (7, 8) in order to dampen the sound, in particular of bearing play-related contact noise and vibration or humming noise.