A Probabilistic Approach to Engine Balance

1999 ◽  
Vol 122 (4) ◽  
pp. 526-532 ◽  
Author(s):  
Dinu Taraza

The paper presents an original probabilistic model of the balance of internal combustion engines. The model considers the manufacturing tolerances and predicts the most probable value of the first-order residual unbalance for engines that—theoretically—have the first order forces and moments balanced. It has been found that, assuming normal distributions of the geometric and mass parameters of the reciprocating mechanisms of a multicylinder engine, the unbalancing forces and moments are statistically distributed according to a Rayleigh law. The mode of the Rayleigh distribution, which represents the most probable value of the residual unbalance, is expressed in terms of the statistical characteristics of the parameters subjected to manufacturing tolerances. In this way, the tolerances and, especially the ones admitted for the reciprocating masses, are directly correlated to the expected value of the residual unbalance making it possible to establish reasonable limits for these tolerances. Validation of the probabilistic balance model is demonstrated by computer simulation. [S0742-4795(00)01704-X]

2009 ◽  
Vol 139 (4) ◽  
pp. 22-33
Author(s):  
Ryszard MOSAKOWSKI

Simple relations describing the resultant moments of inertia forces of the first and second order for all sixty possible configurations of the crankshaft in two-stroke four-cylinder engine have been derived in the paper. A comparative analysis of the crankshafts with different arrangements of cranks have been carried out with respect to the resultant moments of the first and second order inertia forces. The comparison has been carried out for two values of the crank throw to connecting rod length ratio, namely l = 0.3 and l = 0.5. The outcomes of the comparative analysis indicate that irrespective of the l value, within the range of its values having practical meanings, the arrangement of cranks 1-5-3-4-2-6 is the best. As a result of 50% balancing of the moment of the first order inertia forces the differences between various configurations of the crankshaft are significantly reduced and configuration 1-4-2-6-3-5 equals with respect to balancing with the commonly used configuration 1-5-3-4-2-6.


Author(s):  
Petar Kazakov ◽  
Atanas Iliev ◽  
Emil Marinov

Over the decades, more attention has been paid to emissions from the means of transport and the use of different fuels and combustion fuels for the operation of internal combustion engines than on fuel consumption. This, in turn, enables research into products that are said to reduce fuel consumption. The report summarizes four studies of fuel-related innovation products. The studies covered by this report are conducted with diesel fuel and usually contain diesel fuel and three additives for it. Manufacturers of additives are based on already existing studies showing a 10-30% reduction in fuel consumption. Comparative experimental studies related to the use of commercially available diesel fuel with and without the use of additives have been performed in laboratory conditions. The studies were carried out on a stationary diesel engine СМД-17КН equipped with brake КИ1368В. Repeated results were recorded, but they did not confirm the significant positive effect of additives on specific fuel consumption. In some cases, the factors affecting errors in this type of research on the effectiveness of fuel additives for commercial purposes are considered. The reasons for the positive effects of such use of additives in certain engine operating modes are also clarified.


Author(s):  
QI CHEN ◽  
◽  
JINTAO SUN ◽  
JIANYU LIU ◽  
BAOMING ZHAO ◽  
...  

Plasma-assisted ignition and combustion, widely applied in gas turbines, scramjets, and internal combustion engines, has been considered as a promising technique in shortening ignition delay time, improving combustion energy efficiency, and reducing emission. Nonequilibrium plasma can excite the gas molecules to higher energy states, directly dissociate or ionize the molecules and, thereby, has the potential to produce reactive species at residence time and location in a combustible mixture and then to efficiently accelerate the overall pyrolysis, oxidation, and ignition. Previous studies have demonstrated the effectiveness of plasma-assisted combustion by using direct current, alternating currant, microwave, radio frequency, and pulsed nanosecond discharge (NSD). Due to the complicated interaction between plasma and combustion in different types of plasma, detailed plasma-combustion chemistry is still not well understood.


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