Noise Control Transmission Methods of the Combustion Engine by Means of Reduction of the Vibration

Abstract

Transmission of vibroacoustic energy from an internal combustion engine (ICE) to its surroundings largely depends on how it is mounted, on available transmission paths and on the construction of the vehicle body and/or its surrounding structures. This is especially true in low speed engines in enclosed areas which generate perceptually weak noise, but strong low-frequency waves which energy has a negative impact on human health, comfort and driving safety especially in prolonged exposure to the source. The primary aim of the article was to analyse components of the ICE unit which had a determining impact on the reduction of low-frequency waves. Thus, the structurally transmitted noise from the ICE to its surrounding structure (body of the passenger vehicle) was analysed. The results of the vibroacoustic measurements were compared to modal analysis in order to determine possible resonance sources in the vehicle body and/or for assessing the influence of the vehicles safety gear on the generated vibroacoustic energy transfer into the cabin area of the passenger vehicle. Measurements were made for a passenger vehicle at rest and operating in its most common operational speed as well as for the stationary ICE of a cogenerate unit (CGU). Measurements and FFT analysis were used for the detection of the vibroacoustic energy sound pressure level (noise) and mechanical vibration. Firstly, the low-frequency noise sources were determined and their direct effects on the human body were investigated. Finally, this paper suggests some measures which may contribute to the reduction of undesirable vibroacoustic energy in enclosed areas.

Monitoring of Machinery Components During Their Life Cycle

“…When measuring mechanical and acoustic vibration, the most modern measuring technique was used from the renowned Bruel & Kjaer (B&K) company, namely the 12-channel B&K PULSE measuring card; accelerometers with usable frequency ranges of 0.2 Hz -12 800 Hz; sound analyser with a usable frequency range up to 25 600 Hz for control recording of measured signals, including residual noise. The attachment of the sensor to the investigated objects was in accordance with the requirements of ISO 5348 [23] on the accelerometer as well as in accordance with the previous experience of the researchers [2][3][4][5][6][10][11][12][13][14][15][16][17][18][19][20][21]. The aim was to ensure that the accelerometer correctly reproduces the movement of the analysed component without interfering with its sound.…”

“…The good and effective diagnostics can prevent damage to other parts of the machine and ultimately accidents, thus significantly reducing the cost of repairing and recycling machine components. A representative example can be, in machine systems, spinning headstocks used in the textile industry, where A-weighting noise levels normally exceed the value of 90 dB, primarily depending on the degree of bearing fault and therefore a timely replacement of the bearings of the spinning unit reduces noise in the working environment and extends the service lifetime of the assigned components of the given machinery and, in case of insufficient vibration isolation, also of nearby building structures [3].…”

Archives of Acoustics

“…The roadway noise contributes to a proportionately large share of the total societal noise pollution. The adverse effects include sleep disturbance (Öhrström, 1989), cardiovascular disease (Qatu et al, 2009), and irritation (Žiaran, Chlebo, 2016). Noise emission can also be related to the quality of the vehicle and indirectly affect the preference of customers when considering buying a new vehicle (Shin, Cheong, 2010).…”

Using of Recycled Materials to Protect the Working and Natural Environment by Reducing Noise and Vibration

“…Other complications arise because of non-uniaxial motion causing nonlinearities (e.g. combustion engine [14]). Damping refers to reduce of mechanical energy from given vibration.…”