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Wyszukujesz frazę "irregularity" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
The effect of engine run irregularity level on oil film over cylinder liner surface
Autorzy:
Iskra, A.
Krzymień, P.
Powiązania:
https://bibliotekanauki.pl/articles/244054.pdf
Data publikacji:
2008
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
oil film
engine run irregularity
Opis:
At idle run the engine operates in extremely unfavourable conditions because of vibrations generated by cyclic forces which makes that oil film parameters on liner surface become critical as well. This paper presents one of the crankshaft vibrations results namely the speed that differs from a generally known dependence described with two harmonics rco sin less than p and 1/2Xrco sin2 less than p. Taking into consideration the deterioration of oil film - the thickness in particular - at low idle speed, a further speed decrease could cause the oil film rupture. This means that in the case of piston-cylinder assembly elements the process of abrasive wear occurs first of all at idle run. Avoiding such situations lead to a considerable extension of engine life. The minimum piston speed outside both dead centres could be increased by the rise in idle run speed. Unfortunately, this leads to an increase in fuel consumption, e.g. when waiting for a green light in urban traffic. The only way to improve the oil film parameters at idle run is to improve the engine speed irregularity level 8. Certain possibilities in this field are offered by the hybrid drive. This paper presents an introductory analysis of possible improvement in oil film parameters over cylinder liner achieved by the decrease in speed irregularity level 8.
Źródło:
Journal of KONES; 2008, 15, 2; 125-129
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
How the number of engine cylinders affects its mechanical efficiency
Autorzy:
Iskra, A.
Powiązania:
https://bibliotekanauki.pl/articles/246924.pdf
Data publikacji:
2010
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
mechanical efficiency
oil consumption
irregularity run
Opis:
The relation between engine principal dimensions, i.e. piston diameter to stroke ratio is the parameter often modified in order to increase engine efficiency and durability. A similar operation is the achievement of given volume for different number of cylinders, which is the subject of the following paper. For recent years the engine manufacturers have been proposing in-line engines of 3, 4, 5 and 6 cylinders more eagerfy than in last century. Obviously engines of lesser cylinder number are proposed for small car s while those of greater number - for most dynamic ones. One can ask a question whether the cylinder number for a certain swept volume affects such parameters as engine efficiency and durability as well as lube oil consumption. There is no simple answer to this ąuestion but simulations performed by the author allow estimating tendencies in changes of those parameters for various numbers of cylinders. Moreover, it is quite vital that engine complex modifications accompanying the change in cylinder number have been taken into consideration in a course of carried out tests. Lesser number of cylinders for the same volume results in more solid pistons and connecting rods, worse engine run irregularity and soon. The paper presents introductory conclusions which allow selecting an engine of the cylinder number that ensures the best economical and dynamical parameters for a given car.
Źródło:
Journal of KONES; 2010, 17, 2; 153-158
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Speed irregularity characteristic of low speed, two-stroke marine diesel engine applied as vessels main propulsion
Autorzy:
Kowalak, P.
Powiązania:
https://bibliotekanauki.pl/articles/244760.pdf
Data publikacji:
2008
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
transport
marine diesel engines
combustion processes
speed measurement
speed irregularity
Opis:
The piston engine irregularity is a consequence of the uneven power supply from the engine units. As such, it contains valuable information about engines units working process. Unfortunately, it is strongly influenced by torsional vibration, resonance, and propeller behaviour. In order to better understand the speed irregularity phenomena the instantaneous speed was recorded and its characteristic against engine mean speed was developed. Some statistical parameters: standard error and deviation as well as variance were determined. The results were compared with propulsion plant torsional vibration. The presented results show that the irregularity of the long stroke engine's speed is strongly influenced by torsional vibration phenomena. The analyzed engine has a bared speed range 37-43 rpm. Exactly around that range, the speed irregularity reaches its maximum values of 18% of mean speed. The analysis can be considered as qualitative look into the phenomena. However even based on the presented analysis one can observe some practical inferences. The common type of electronic indicators is used to simplify the measurement by assuming that the shaft speed is equal in between the pickup pulses. In order to increase the accuracy of the indicated power determination the use of such instrument should be avoided in the speed range, which is a multiple number of the barred speed. Due to the fact that the shaft speed is irregular especially in the ranges where torsional resonance may occur the piston positioning (for example for TDC determination) purpose procedure should take it into account.
Źródło:
Journal of KONES; 2008, 15, 4; 263-268
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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