Wyniki wyszukiwania - BazTech

1

Increasing the accuracy of the mean indicated pressure determination by appointment of the TDC cylinder position

Pawletko R.

Journal of KONES

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2014

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Vol. 21, No. 4

397--404

EN

The paper describes the problems of mean indicated pressure determination and the piston TDC (Top Dead Centre) position impact on this parameter in marine diesel engines. Mean indicated pressure Pi is one of the most important diagnostic parameters of marine engines. On the basis of his parameter, the assessment of the technical condition of each cylinder as well as the regulation of injection equipment can be made. Most of the available electronic indicators enable automatic calculation of mean indicated pressure on the basis of progress indicator diagram. As the research shows the greatest impact on the accuracy of the designation mean indicated pressure has errors of piston TDC position. These errors can be significant and therefore this may lead to engine misdiagnosis. The actual TDC piston correction methods were discussed, and were justified the need of their use in marine engines, despite the wide use of methods of determining the angular position of the crankshaft. The original method of TDC correction based on the model of curve of the compression with the exponent of a polynomial was introduced. The proposed method of TDC correction has been verified for different types of marine engines.

2

Increasing the accuracy of the mean indicated pressure determination by appointment of the TDC cylinder position

Pawletko R.

Journal of KONES

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2014

|

Vol. 21, No. 2

251--258

EN

The paper describes the problems of mean indicated pressure determination and the piston TDC (Top Dead Centre) position impact on this parameter in marine diesel engines. Mean indicated pressure Pi is one of the most important diagnostic parameters of marine engines. On the basis of its parameter, the assessment of the technical condition of each cylinder as well as the regulation of injection equipment can be made. Most of the available electronic indicators enable automatic calculation of mean indicated pressure on the basis of progress indicator diagram. As the research shows the greatest impact on the accuracy of the designation mean indicated pressure has errors of piston TDC position. These errors can be significant and therefore this may lead to engine misdiagnosis. The actual piston TDC correction methods were discussed, and they justified the need of their use in marine engines, despite the wide use of methods of determining the angular position of the crankshaft. The original method of TDC correction based on the model of curve of the compression with the exponent of a polynomial was introduced. The proposed method of TDC correction has been verified for a different types of marine engines.

3

Evaluation of current developments and trends in the diagnosis of marine diesel engines based on the indicator diagrams analysis

Pawletko R., Polanowski S.

Journal of KONES

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2014

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Vol. 21, No. 4

389--396

EN

The paper analyses the current offer of combustion pressure sensors for use on marine engines under operating conditions, methods of data acquisition, methods of determining TDC position and methods of obtaining diagnostic information from the indicator diagrams. Terms of continuous work on marine engines themselves only: new ABB cylinder pressure sensor, the piezoelectric sensors from KISTLER and AVL companies, but with limitations, the main ones being stability at high temperature. Another important issue for the accuracy of mean indicated pressure and heat released characteristics determination is referred to TDC position on the indicator diagrams. TDC is appropriate thermodynamic point, it is hardly determinable in the presence of interference and lack of sufficient information – but is used, for example in ABB solution. One of the sources of diagnostic information is to analyse trends in some parameters, which, unfortunately, is very difficult in environments with varying engine loads. Further progress in the diagnostic use of indicator diagrams should be associated with the use of the heat released characteristics and the net internal efficiency, which as shown by the results of preliminary tests can be used to assess the accuracy of the injection and combustion of fuel, including gas fuel. Supplementing these methods may be the use of vibration and noise to detect certain malfunctions.

4

Low speed marine diesel engine diagnosis based on passive experiment

Polanowski S., Pawletko R.

Journal of Polish CIMAC

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2012

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Vol. 7, no 2

161-166

EN

Analysis of the indicator diagram is the basis of technical state evaluation of marine diesel engines. The indicator diagram contains a large amount of diagnostic information. In most cases, analysis of the graph is reduced to determination only the maximum pressure or mean indicated pressure. It seems appropriate to determine the possibility of use heat release characteristics for the diagnostic purpose. The paper presents results of studies related to the use of indicator diagrams for the diagnosis of high power marine diesel engine. The results include a comprehensive approach to problems of use of the cylinder pressure curves for the evaluation of the technical condition of the engine. The problem of dynamic adjustment of the GMP position, smoothing distortions due to the impact of the channel and indicator valve were considered. Diagnostic analysis includes also the designation of the heat release characteristics on the basis of the curves pressure in the engine cylinder. The algorithms allow to determine both the curves of heat release rate q and the heat released Q. The curve of heat release rate q is a full equivalent to fuel injection pressure curve in the fuel pipes. It allows identification of the failure of the injection system. The curve of Q allows such determination and additional assessment of internal efficiency of the cylinder. The analyzed indicator diagrams were obtained during the sea voyage with the use of the stationary electronic indicator PREMET. The pressure sensor were placed on the indicator valves.

5

Influence of gas channels of medium speed marine engines on the accuracy of determination of diagnostic parameters based on the indicator diagrams

Pawletko R., Polanowski S.

Journal of Polish CIMAC

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2012

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Vol. 7, no 2

139-146

EN

Analysis of the indicator diagram is the basis of technical state evaluation of marine diesel engines. The indicator diagram contains a large amount of diagnostic information. A major problem for the diagnostic use of the indicator diagrams in case of medium speed engines are distortion caused by the gas channels between the cylinder and the pressure sensor. Indicator channel and valve may introduce significant distortions which increases with increasing engine speed. The paper presents results of results of the analysis of the indicator diagram of engines in onboard service, and research conducted on the medium speed laboratory engine Al 25/30. These engines are characterized by gas channels of high complexity. During laboratory research pressure measurement (indication) was made by the sensor placed directly in the cylinder (instead of starting air valve), before the indicator valve (with special Kistler adapter) and on the indicator valve. Distortion of heat release characteristics for the sensor placed on the indicator valve is important, but it is estimated that diagnostic information is not erased. For medium speed engines is to be expected the use of a portable pressure sensors placed on the indicator valve. For this reason, further research is needed to assess the impact of channels and valves on different cylinders. During the research the course of heat release rate q and the heat released Q were determined. The curve of heat release rate q is a full equivalent to fuel injection pressure curve in the fuel pipes. It allows identification of the failure of the injection system. The curve of Q allows such determination and assessment of internal efficiency of the cylinder.