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Investigations of the Friction Losses of Different Engine Concepts. Part 1: A Combined Approach for Applying Subassembly-Resolved Friction Loss Analysis on a Modern Passenger-Car Diesel Engine

1
VIRTUAL VEHICLE Research Center, Inffeldgasse 21A, 8010 Graz, Austria
2
AVL List GmbH, Hans-List-Platz 1, 8020 Graz, Austria
3
Institute of Internal Combustion Engines and Thermodynamics—Graz University of Technology, Inffeldgasse 19, 8010 Graz, Austria
*
Author to whom correspondence should be addressed.
Lubricants 2019, 7(5), 39; https://doi.org/10.3390/lubricants7050039
Received: 29 March 2019 / Revised: 16 April 2019 / Accepted: 17 April 2019 / Published: 26 April 2019
(This article belongs to the Special Issue Automotive Tribology)

Abstract

This work presents the application of a combined approach to investigate the friction losses in a modern four-cylinder passenger-car diesel engine. The approach connects the results from engine friction measurements using the indication method and the results from journal-bearing simulations. The utilization of the method enables a subassembly-resolved friction loss analysis that yields the losses of the piston group, crankshaft journal bearings, and valve train (including the timing drive and crankshaft seals). The engine and engine subassembly friction losses are investigated over the full speed and load range, covering more than 120 engine operation points at different engine media supply temperatures ranging from 70 to 110 C. The subsequently decreasing lubricant viscosity due to higher engine media supply temperatures allow for the identification of friction reduction potentials as well as possible risks due to an onset of mixed lubrication. Furthermore, additional strip-tests have been conducted to determine the friction losses of the crankshaft radial lip seals, the timing drive, and the crankshaft journal bearings, thus enabling a verification of the calculated journal-bearing friction losses with measurement results. For the investigated diesel engine, a friction reduction potential of up to 21% could be determined when increasing the engine media supply temperature from 70 to 110 C, at engine speeds higher than n = 1500 rpm and part load operating conditions. At low engine speeds and high load operations, the friction loss reduction potential is considerably decreased and below 8%, indicating mixed lubrication regimes at the piston group and valve train. View Full-Text
Keywords: engine friction; friction measurements; friction loss distribution; subassembly friction; journal-bearing simulation; valve train; journal bearings; piston group engine friction; friction measurements; friction loss distribution; subassembly friction; journal-bearing simulation; valve train; journal bearings; piston group
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
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Knauder, C.; Allmaier, H.; Sander, D.E.; Sams, T. Investigations of the Friction Losses of Different Engine Concepts. Part 1: A Combined Approach for Applying Subassembly-Resolved Friction Loss Analysis on a Modern Passenger-Car Diesel Engine. Lubricants 2019, 7, 39.

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