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Analysis of gear noise and dynamic transmission error measurements
KTH, Superseded Departments, Aeronautical and Vehicle Engineering. (Vibro acoustics)
2004 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Measurements of dynamic transmission error (DTE) and noise have been performed on a truck gearbox. The DTE is related to the dynamic properties of the complete gear system. To investigate the coupling between noise and DTE, the correlation between noise and DTE is calculated for fixed speeds, as the torque is increased. The highest correlation is found for the low split gear pair, which is located closest to the gearbox housing. When the correlation is low, one of the reasons can be a resonance of the shafts, although not all resonances effect the correlation between noise and DTE. The DTE is also compared to calculated static TE for the gear teeth. Both the DTE and noise for the fifth gear increases as the torque is increased. The calculated static TE shows the opposite trend and decreases as the torque is increased.

Place, publisher, year, edition, pages
New York: ASME , 2004. 1-9 p.
Keyword [en]
Gears, Gear noise, transmission error
National Category
Vehicle Engineering
Identifiers
URN: urn:nbn:se:kth:diva-11842Scopus ID: 2-s2.0-19544385769OAI: oai:DiVA.org:kth-11842DiVA: diva2:284820
Conference
2004 ASME International Mechanical Engineering Conference
Note
QC 20100719Available from: 2010-01-12 Created: 2010-01-08 Last updated: 2010-11-30Bibliographically approved
In thesis
1. On Noise Generation and Dynamic Transmission Error of Gears
Open this publication in new window or tab >>On Noise Generation and Dynamic Transmission Error of Gears
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Noise from heavy trucks is an important environmental issue. Several sources contribute to the total noise level of a vehicle, such as the engine, gearbox, tires, etc. The tonal noise from the gearbox can be very disturbing for the driver, even if the noise level from the gearbox is lower than the total noise level. The human ear has a remarkable way of detecting pure tones of which the noise from loaded gears consists of. To be allowed to sell a heavy truck within the European Union, the so called pass-by noise test must be completed successfully. The maximum noise level permitted is 80dB(A) and undercertain conditions, the gearbox can be an important contributor to the total noise level. Gear noise is therefore an important issue for the automotive industry.

In this thesis gear noise and dynamic transmission error is investigated. Traditionally, transmission error (TE) is considered to be the main excitation mechanism of gear noise. The definition of TE is ”the difference between the actual position of the output gearand the position it would occupy if the gear drive were perfect”. Measurements of dynamic transmission error (DTE) and noise have been performed on a gearbox. The measurement object was a commercial truck gearbox powered by an electrical motor. The torque used was in the normal operating range of the gearbox and the correlation between gear noise and DTE, when the torque is changed, is investigated. The result differs for different gear pairs and for the first gear stage, located close to the housing, the correlation is high for most speeds. The measured DTE and noise show a poor correlation with calculated transmission error. A minimisation of TE therefore does not necessarily mean a minimisation of gear noise.

A transfer function can be employed to calculate the relationship between DTE and noise. The general trend of the gear noise is an increase of 6dB per doubling of the rotational speed together with fluctuations around the mean due to resonances of the system. The magnitude of the transfer function can be estimated using the amplitudesof the gear mesh orders and harmonics.

Two gear pairs with similar macro geometry but different profile modifications are investigated. Although the gear pairs have similar transmission error, the noise level display a significantly different trend, further strengt hening the position that transmission error is not the single most important gear noise excitation mechanism. Further analysis concludes that shuttling forces and friction forces can be more important than what is often suggested. A dynamic model including transmission error and shuttling forces is used to investigate the two gear pairs. The bearing forces show that for some frequency regions shuttling forces can be of the same order of magnitude as the forces caused by transmission error.

This work highlights the importance of considering other excitations of gear noise besides transmission error when designing quiet gears. The influence of transmission error can not be determined by investigating the gears only. A deeper knowledge of the gear system is needed in order to minimise gear noise for a specific gear design.

Place, publisher, year, edition, pages
Stockholm: KTH, 2009. 17 p.
Series
Trita-AVE, ISSN 1651-7660 ; 2009:89
National Category
Vehicle Engineering Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-11858 (URN)978-91-7514-537-2 (ISBN)
Public defence
2010-01-29, Sal F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20100719Available from: 2010-01-13 Created: 2010-01-12 Last updated: 2010-07-19Bibliographically approved
2. Analysis of dynamic transmission error and noise from a two-stage gearbox
Open this publication in new window or tab >>Analysis of dynamic transmission error and noise from a two-stage gearbox
2005 (English)Licentiate thesis, comprehensive summary (Other scientific)
Place, publisher, year, edition, pages
Stockholm: KTH, 2005. 14 p.
Series
Trita-AVE, ISSN 1651-7660 ; 2005:34
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-488 (URN)
Presentation
2005-11-17, Seminarierum 74, Teknikringen 8, Stockholm, 13:15
Opponent
Supervisors
Note
QC 20101130Available from: 2005-11-11 Created: 2005-11-11 Last updated: 2010-11-30Bibliographically approved

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Citation style
  • apa
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