Publications

This selection of publications provides an overview of the main application areas for ROTEC equipment. A wide variety of engine and powertrain testing applications are included. VISPIRON is dedicated to delivering exceptional test equipment to its customers with innovative engineering solutions.


MEASUREMENT AND ANALYSIS OF VALVETRAIN DYNAMICS AND DUAL-MASS FLYWHEEL CHARACTERISTICS

Abstract
Over the last decade the automotive industry has achieved significant progress in improving both fuel economy and driving comfort. In order to make accurate assessments of engine and transmission capabilities state-of-the-art testing equipment in the development phases needs to be used. This paper presents experimental investigations involving two areas of current interest: valvetrains and dual-mass flywheels. Instrumentation used, test configurations, test parameters and analysis software are discussed.

Higher valvetrain efficiency is a key factor in reducing fuel consumption and emissions. Methods for measuring valve motion are outlined. The increasing complexity of valvetrain systems demands application-specific test and analysis software. Valve lift, valve velocity and valve acceleration curves versus camshaft speed and angle are presented.
Measured data are compared with kinematic curves and the dynamics of valve opening, closing and seating are discussed.

The dual mass flywheel or DMF is increasingly used in vehicles fitted with manual transmissions in order to optimise driving comfort by reducing noise and vibration in the driveline. The DMF eliminates excessive gearbox rattle and reduces gear change/shift effort. Measurement data are used to describe the pros and cons of single and dual mass flywheel systems. Typical analyses include DMF wind-up angles and the comparison of torsional vibration amplitudes on the engine and transmission sides.

Read the entire document as a PDF Part 1 and PDF Part 2

 

 

MEASUREMENT AND ANALYSIS OF TORSIONAL VIBRATION IN AUTOMOTIVE DEVELOPMENT

Abstract
Torsional vibrations are mechanical vibrations caused by time-alternating torques which are superimposed on the otherwise steady running speed of a rotating shaft.  In automotive engineering torsional vibration is primarily caused by the fluctuations in engine power output. This results in crankshaft angular velocity fluctuations which cause twisting and untwisting of the shaft.  The effects of torsional vibration are amplified by torsional resonance which occurs when a shaft‘s natural frequency coincides with its torsional frequency.

Excessive torsional vibrations can result in unwanted noise, powertrain component wear and, in severe cases, broken shafts.  To identify such effects in advance and adopt measures to avoid them before ex-cessive damage has occurred, the development engineer requires dedicated, state-of-the-art measuring equipment incorporating application-specific software to simplify measurement setup and provide quick analysis.

This paper begins by discussing several subtleties of dynamic torsional vibration testing. Two applications in automotive development – clutch/dual-mass flywheel measurements (conducted in-vehicle) and timing belt optimisation (on a dedicated engine test rig) – are then described in detail.

Read the entire document as a PDF

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