The wearing out compensation of diesel engines combustion chambers by modern systems implementation.

Ostoia, Daniel ; Negoitescu, Arina ; Tokar, Adriana 等

1. INTRODUCTION

The increase of the environment pollution generated by the internal combustion engines the vehicles are equipped with, represent a desideratum both for the manufacturers and for those who use them.

The problems generated by this pollution are complex and their causes are various (Negrea, 2001). Most researches refer to the new product's technology, but the influences of the wears that appear as a result of the exploitation are more difficult to underline and to mend.

This study approaches both the possibility to take over information regarding the wear of some engine devices and the possibility to mend the efects of these inerent wears by mending the engine's actuators' parameters. The modern engines cannot satisfy the requests imposed by pollution but by using the electronic and informatics elements, thus it results a mechatronic complex. The present work is a method for quantifying and reducing the wear effects in the combustion chamber by using the electronic and informational up-dating systems of some functional parameters. Thus, up-dating the new data of the mechanic parameters in the electronical administration of the engine (ECU), new configurations for the new functioning situations of the engine can be created.

2. THE RESEARCH METHOD

The experimental study of the pressure loss in the combustion chamber was achieved on a M 511 diesel engine. It is characterized by a power of 5 kW for 2500 rot/min speed and is switched on with the engine through the C coupling.

The engine parameters (the indicate pressure into the cylinder, the injection pressure) are measured with two transducers, a position photoelectric transducers, a Kistler type and an Elkon one. These transducer signals are introduced in a signal converter and than are captured in an acquisition device type Labview. The converter signals are processed by this device and with LabView software are saved in ASCII files for further computations.

The engine speed and smoke are measured with a Type AVL device. The sealing degree of combustion chamber is a result of wearing out compensation and the important parameters of degree comparison.

[FIGURE 1 OMITTED]

In order to simulate and control the sealing degree of combustion chamber, it was assembled a device that allows fitting gauged holes into the combustion chamber. Through these holes the motor fluid is lost and the performances of the combustion chambers decrease.

The tests on test stand were achieved in the following cases:

--engine under normal working conditions which means the hole diameter of chamber is equal to 0mm, so there are no loses in combustion chamber;

--engine under working conditions characterized by the hole diameter equal to 2 mm, so through this hole are supplementary losses. The test stand is presented in Figure 1.

The testing method purpose was to achieve verification on partial automated experimental installation that can be found in the Internal Combustion Engines lab of MMUT Department of University Politehnica of Timisoara (Ostoia, 2006; Ostoia et al., 2005). The stall land auxiliary installations were equipped as to obtain some parameters established at tests objectives.

The device has a good accuracy for a relevant experimental study duet o fact that convergent results were also experimental obtained for piston rings with different wear degrees.

The experimental program was achieved as every testing case was recurring for a convenient number of times and the resulted values are representing average values of these tests. The device was assembled into the combustion chamber and into the device can be achieved fitting gauged holes in order to simulate the losses through leakiness caused by piston rings wear.

In order to compare the simulation cases were achieved tests for the engine equipped as it follows:

--new piston rings

--weared piston rings

--new piston rings with fitting of 2mm device

To compensate the loss caused by the non-tighten of the combustion chamber due to the wears, it is proposed a change in the injection pressure from 175 bar standard to 200 bar.

[FIGURE 2 OMITTED]

Thus, together with the information received from the sensor in the combustion chamber, the engine's actuators' parameters can be corrected by changing the values of the Electronic Central Unit (ECU).

These changes must be corrected for each phase, together with their own diagnosis on board (OBD), but i tis preffered to be made together with the change of parameters in the combustion chamber (Madaras, et al., 2006).

The diagram block of connection between transducer pressure from combustion chamber TP, electronic control unit (ECU) and injection pressure actuators I.A. is shown in Figure2.

3. THE EXPERIMENTAL RESULTS AND THEIR INTERPRETATION

The main experimental data regarding the performance parameters of the engine (the effectiv power [P.sub.e], the engine speed n, the cyclic dosage [d.sub.c], the injection pressure p) are plotted in Figure3 and Figure 4 (Ostoia, et al., 2005).

[FIGURE 3 OMITTED]

[FIGURE 4 OMITTED]

4. CONCLUSION

By analyzing the accomplished researches regarding the modification of conditions from the combustion chamber, results the following conclusions:

--The modulating methods allow the losses through leakiness evaluation of the engine piston rings

--By knowing the engine behavior in losses case, functional and constructive parameters can be adjusted as the engine working conditions to be optimum

--The tested engine and the ones of its family are energetically influenced by the sealing of the combustion chamber

--The compression and sealing degrees of the combustion chambers are corroborated with the wear of the sealing element. This fact was observed on the comsumption increasing together with the increase of leakinsess the combustion chamber

--The compensation of the leakeage due leakiness could be achieved through an electronic management of injection system until a certain value of these losses.

--The parameters correction of engines will be realized by unit electronic control (ECU) when the transducers of pressure indicate a different value of standard.

This study makes a connection between mechanics parameters (wearing out, effective power, pollution degree) and the electronics and informatics device which equipped the new generation of modern engine.

The study can be especially applied for high capacity diesel engines. These engines usually are related to heavy vehicles (trucks, buses) with an exploitation period larger than the cars one and they presume a high exploitation price.

The results for pollution and energetic performances improvements create the possibility of the combustion chambers wear degree quantification.

The experimental results of this study represent a research direction which must be in accordance with the studies regarding the engine operation optimization.

5. REFERENCES

COFRET, 2006

Madaras L, Ostoia Daniel, Holotescu S., (2006). The influence of loses diesel engine combustion chambers to mechanical indicate work at idle characteristic, The Third Edition of the French-Romanian Colloquim Ostoia, D. (2006). Studies and researches of the formation control of mixture and burning and the influence of behaviour in work to the combustion chamber in correlation with pollution conditions to the diesel engines, Ph.D. Thesis, University Politehnica of Timisoara

Negrea, D. (2001). Processes into internal combustion diesel engine. Economicity. Pollution control. Vol I-II, Ed. Politehnica, 973-9389-89-9, Timisoara

Ostoia, D., Negoitescu, A., S., (2005) A study regarding the combustion chambers behavior in corelation with emitted noxe sat diesel engines, The 30th Annual Congres of the American Romanian Academy of Arts and Sciences, The Academy of Economic studies of Moldova, pp. 576-578, 9975-313-2, july 200, Chsinau

Ostoia, D., Negoitescu, A., S., Tokar,A.,(2005). Improvemet possibilies of fuel pulverization at the multiple jet sprayer's by functional altering of the injection system, Scientific reunion of the special program of the Alexander von Hhumboldt foundation concerning the reconstruction of the South Eastern Europe, Sustailnability for humanity & enviroment in the extended connection field science-economy-policy, 1, pp. 131-134, 973-65-25-204-3, february 2005, Timisoara