CC BY
19TECHNICAL SCIENCES
CREATING AN IMITATION MODEL FOR DIAGNOSING AN AUTONOMOUS POWER SUPPLY
Zaichenko S.
National Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute ",
Professor of department of electromechanical equipment Doctor of technical Sciences, Professor, ORCID: https://orcid.ors/0000-0002-8446-5408
Shevchuk S.
Professor of department of electromechanical equipment Doctor of technical Sciences, Professor, ORCID: https://orcid.org/0000-0002-8446-5408
Adjeby A. postgraduate
National Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute",
Abstract
A simulation model of the process of diagnosing an autonomous electric generator based on an internal combustion engine is developed. The developed model has been experimentally confirmed. The developed simulation model of the diagnostic process allows you to determine the degree of compression of the generator from the starting currents. An inverse proportional linear dependence of the change in the compression coefficient on the ratio of the current ratio is established.
Keywords: diagnosis, compression ratio, generator, engine
The only solution to provide reliable power supply for petroleum industry is the use of power stations with internal combustion engines. The new reliable work of electrical equipment is a complex of diagnostic procedures for determining the technical condition and timely repair. At the heart of the diagnostic process is the receipt of experimental data, diagnostic features, which, depends on the informativeness degree, determine the state of the subject under the study. The main reason for the power generating plants with internal combustion engines loss of the working state is the wear of a cylinder-piston group. For the diagnosis of internal combustion engines, which allows in most cases, by comparing the experimental data obtained with the normative ones, to establish a technical diagnosis, number of diagnostic methods are provided. One of the progressive methods that allows the diagnostics of the cylinder-piston group's airtightness is to measure compression using compressors and compressorso-grafs. The disadvantages of this method include the high workload associated with the engine disassembly and data inaccuracy.
The indicated drawbacks are deprived in diagnostic system of the internal combustion engine which use the level of the starter current as a diagnostic parameter. Application of this method allows to significantly increase the results informality and reliability with simultaneous reduction of labor costs. However, this method of diagnosing requires pre-set data on the currents and the voltage value of starter engines for its implementation, which significantly limits the application of this method, and makes it impossible in case of creation of new engines models.
Analysis of publications that are devoted to the study of the system of electric starter internal combustion engine shows the difficulty of establishing the dependence of the current level on the angle of rotation of
the crankshaft or stator shaft. Also, the conducted studies allow to neglect the change of inertial parameters of the system.
In view of the above, we will determine the average current of the electric starter per engine cycle to simplify the problem, that is, two revolutions.
Generally, the energy balance of the diagnosis system is as follows
n n
Xa=XQ
(1)
7=1 7=1
where A. - the operation of an external energy
source; Q - energy consumption for the implementation of internal processes during engine rotation.
The operation of external power sources is based in this case on the starter for one cycle of the engine. Given the gear ratio i :
Ast = 2mM = ANst (2)
where M -the starter moment; Nst - the starter
power; At - time of one engine cycle.
The starter power can be determined by technical documentation or by dependency:
Nt = UI, (3)
U - the battery voltage(12B); I - average current per engine cycle.
Energy costs for the implementation of internal processes during engine rotation are the cost of friction of parts and thermodynamic gas processes
X 0 = 0/,+Qd (4)
/ i i^-i i=1
The energy consumption of the generator rotation can be neglected due to the engine start frequency, which is within 5% of the rated generator speed.
The friction costs of the parts Q^. are based on a
number of components that are associated with the piston stirring, crankshaft rotation, oil pump operation, gas
distribution. The friction cost of parts Q^. can be determined when starting the engine without a spark plug:
^ - the indicator of the efficiency of the adiabatic process[]:
! 1
m =1 —— , (7)
Qjr = uiy*
(5)
/ - the starter current without the spark plug.
The essence of the costs of gas thermodynamic
processes Qacl in the compression of air with heat.
From the known dependence of the indicator of the efficiency of the flow of gas thermodynamic processes
Qad equal to:
Qad =ViAad , (6)
ff-1'
where n' - test factor 1 < n < k(1.3); £ - the degree of compression of the engine.
The created system of equations (1-7) allows to change the compression ratio from the state of the motor of the autonomous power source. The establishing of the true compression ratio for an autonomous power supply engine allows you to set the system's energy efficiency and resource.
The scheme of the experimental stand of the process of diagnosing the autonomous generator is shown in fig. 1.
Fig. 1. Scheme of the experimental stand
The first parameter that was measured was the starting current of the generator (average current per engine cycle). The average value of the starting current of the generator was:
/ = 238 • 0.07462 = 11.15A.
After measuring the starting current with the spark plug, the spark plug is removed and the starter rotation current is measured. 3.25 (red line). The average value of the generator scroll current was:
I, = 190 • 0.07462 = 14.23A
To determine the values of the compression ratio and the energy efficiency coefficient on the passport, set the necessary values (Fig. 3.26).
Based on the passport Honda GX 200:
A = 0.6s;
U = 12V;
p0 = 100000/a;
V0 * 0.0002m3.
Substituted for expressions for the compression ratio of the current ratio and the energy conversion efficiency of the autonomous power source:
£ = 7.639; 0.366.
The following is an indication of the fact that the passport value is more than one for this model of a warehouse engine, 8 units. The magnitude of the bending of the method propounded is between 3.5%.
References
1. Dyakov I.F., Zeynetdinov R.A. Designing of tractor engines // Ulyanovsk: UlSTU. - 2004.
