Further Experimental Investigation of Motored Engine Friction Using Shunt Pipe Method

Abstract

<div class="section abstract"><div class="htmlview paragraph">Mechanical friction is a significant power dissipater in the internal combustion engine. In the effort of designing more efficient and less pollutant engines, friction reduction is certainly on the agenda to be investigated. Such investigation cannot be possible without an accurate measurement of the same quantity. This publication regards a continued study on the mechanical friction determination in an internal combustion engine using the Pressurised Motoring Method. In this work, the friction mean effective pressure of a four-cylinder compression ignition engine was investigated with varying engine speed and manifold pressurisation, using a dedicated high precision sensor for the correct determination of the cylinder Top Dead Centre position. Two different measurement sessions were carried out; in the first, air was employed as pressurisation medium, testing 32 different setpoints; in the second, instead, with the aim to test the effect of the variation of thermochemical properties of fluids on the thermodynamic loss angle, Argon was used in place of air in 18 different setpoints. In the motored condition it is widely accepted that the brake torque is a measure of the losses of the engine and therefore has to be supplied by the driver, in our case the AC motor. The 2000 rpm region was explored with the aim to investigate the high motoring brake torque observed in a previous work from the same authors [<span class="xref">1</span>]. An investigation of the volumetric efficiency effect on motoring brake torque is also presented in the paper. Values of IMEP, BMEP, FMEP, peak in-cylinder pressure, loss angle and other parameters are given. The loss angle measured at each setpoint using the TDC sensor is compared with the loss angle evaluated by the use of two thermodynamic methods developed by Stas’ [<span class="xref">2</span>] and Pipitone [<span class="xref">3</span>].</div></div>

Study on the frictional properties of the top ring-liner conjunction for different-viscosity lubricant

“…), which friction power loss contributes significantly to the engine energy efficiency. [2][3][4] In these low-friction technologies, the application of low-viscosity lubricant has been recognized as an effective approach to reduce the friction power loss of the piston assembly. 5 However, due to the complex working conditions, the effect of lubricant viscosity on the frictional properties of the piston assembly is still not entirely clear.…”

Test bench development and implementation for experimental determination of mechanical losses in single cylinder internal combustion engines

“…Related to mechanical losses, these are composed by the rubbing friction of all the moving pairs, the pumping work due to the intake and exhaust process backpressure and the power needed to drive the auxiliary systems [16][17][18][19][20][21]. Only the friction losses consume 4−15 % of the energy provided by the fuel [8], i.e., that by reducing the mechanical loss is possible to improve the net engine efficiency.…”