An experimental investigation of camshaft dynamics.

Anderson, Stefan W.

Abstract

The construction of the internal combustion engine, since its first use in vehicles in 1865, has steadily increased in complexity. It is because of this increase of complexity that has lead to increase in vibration levels throughout the engine. Unwanted vibrations in the camshaft area can lead to accelerated wear of the valvetrain mechanism, causing the engine to lose power. To try and gain a better understanding of the vibration levels in the camshaft area it was decided to focus this research project on one particular aspect of valvetrain dynamics. It tried to determine whether there was a simple direct relationship between the rotational vibration measured from the camshaft and the vibrations transmitted through the camshaft bearings. Using the influence coefficients theory for a static linear system equations were developed for use in a dynamic system. A test rig was designed and built around a Ford 2.0L DOHC engine so that experimental vibration information, in the form of frequency response tests, could be determined and used in the developed equations to determine the values of the influence coefficients. The values determined for the influence coefficients found that there would appear to be no direct relationship between the two sets of vibration information. After further analysis to try and determine whether there were any particular similarities between the values for the influence coefficients, using experimental data measured at the same position in the engine but at different speeds, no apparent similarities could be determined. This could be due to two possible reasons. Firstly, the vibration measured by the accelerometers attached to the camshaft bearings is not solely due to the vibration of the camshaft but due to all the vibration levels transmitted throughout the engine. Thus, invalidating the initial premise that there is a simple direct relationship between the two sets of vibration data and thus also the working equations used. One possible next step of this research project would be to try and overcome these problems by taking the other vibrations into account in the initial equations. Secondly, using the influence coefficient theory for a static loading case could be developed for a dynamic case. In that case a more realistic set of equations would have to be developed and used.

Citation

ANDERSON, S.W. 1996. An experimental investigation of camshaft dynamics. Robert Gordon University, MPhil thesis. Hosted on OpenAIR [online]. Available from: https://doi.org/10.48526/rgu-wt-2807281

• Thesis Type: Thesis
• Deposit Date: May 9, 2025
• Publicly Available Date: May 9, 2025
• DOI: https://doi.org/10.48526/rgu-wt-2807281
• Keywords: Camshaft; Vibration; Internal combustion engine; Valvetrain; Influence coefficients; Frequency response; Dynamic system
• Public URL: https://rgu-repository.worktribe.com/output/2807281
• Award Date: Sep 30, 1996