Study of Friction Reduction Potential in Light- Duty Diesel Engines by Lightweight Crankshaft Design Coupled with Low Viscosity Oil

Mafrici, Salvatore

doi:10.4271/2020-37-0006

Cited by 2 publications

(2 citation statements)

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“…Here, B is the engine bore in (m), p cyl is the in-cylinder pressure in (bar), ϑ cyl is the gas temperature in (K), C 1 is a constant which is defined differently for the high-pressure cycle and the low-pressure cycle, as specified in ( 9), and ν is the characteristic velocity defined in (8). Hence, the variable ν cm is the mean piston speed in (m/s), V c is the clearance volume, V is the actual cylinder volume, both in (m 3 ), and p mi is the mean indicated pressure in (bar), whereby a lower boundary of 1 bar has to be set.…”

Section: Wall Heat Lossesmentioning

confidence: 99%

“…For ICEs, it is crucial to maximize the thermal efficiency across their relevant operating range. Generally helpful for that purpose are any efforts to reduce the friction and weight of moving/rotating parts [7,8]. An increase of the compression ratio helps in improving the thermal efficiency, but is often limited by knock in the case of sparkignited engines.…”

Section: Introductionmentioning

confidence: 99%

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Increased Internal Combustion Engine Efficiency with Optimized Valve Timings in Extended Stroke Operation

et al. 2021

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Spark-ignited internal combustion engines are known to exhibit a decreased brake efficiency in part-load operation. Similarly to cylinder deactivation, the x-stroke operation presented in this paper is an adjustable form of skip-cycle operation. It is an effective measure to increase the efficiency of an internal combustion engine, which has to be equipped with a variable valve train to enable this feature. This paper presents an optimization procedure for the exhaust valve timings applicable to any valid stroke operation number greater than four. In the first part, the gas spring operation, during which all gas exchange valves are closed, is explained, as well as how it affects the indicated efficiency and the blow-by mass flow. In the second part, a simulation model with variable valve timings, parameterized with measurement data obtained on the engine test, is used to find the optimal valve timings. We show that in 12-stroke operation and with a cylinder load of 5 Nm, an indicated efficiency of 34.3% is achieved. Preloading the gas spring with residual gas prevents oil suction and thus helps to reduce hydrocarbon emissions. Measurements of load variations in 4-, 8-, and 12-stroke operations show that by applying an x-stroke operation, the indicated efficiency remains high and the center of combustion remains optimal in the range of significantly lower torque outputs.

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Section: Wall Heat Lossesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%