ANALYTICAL METHOD FOR PISTON TOP DEAD CENTER DETERMINATION IN A PARAMETRIC DIAGNOSTIC SYSTEM FOR MARINE DIESEL ENGINES

Abstract

Introduction. A novel approach to developing a portable real-time parametric diagnostic system for marine engines is proposed. The system leverages modern Android/iOS devices, which receive data from sensors via Bluetooth, perform necessary calculations, and display diagrams and data in real-time. The system under development employs a combination of a gas pressure sensor in the working cylinder and a vibroacoustic sensor, expanding the diagnostic capabilities of marine diesel engines during operation. This solution enables the diagnosis of the fuel injection system, valve timing mechanism, and other engine systems. The objective of this work is to develop a noise-resistant analytical method for determining the Top Dead Center (TDC) position and data synchronization, capable of operating with imprecise input data when testing marine diesel engines during operation. To achieve this, it is crucial to solve the problem of analytical TDC determination, as the system does not use specialized sensors for this purpose. Results. Аn algorithm for TDC determination is proposed, based on the analysis of the original pressure diagram rather than its derivative, minimizing the impact of digital and analog noise. The proposed algorithm for TDC determination and subsequent data synchronization operates without information about the actual compression ratio in the cylinder, which is characteristic of modern engines with variable valve timing. The algorithm also functions with approximate data on charge air pressure, which is refined through iterations. Additionally, a formula for determining the initial TDC position is proposed. Conclusions. The data processing methods presented in this article allow for accurate estimation of indicated power through precise TDC determination, as well as optimal adjustment of engine systems and result monitoring during operation. The proposed approach to real-time marine engine diagnostics offers several advantages over traditional methods. It provides more accurate analysis of the working process, improves control over fuel combustion quality, and helps minimize harmful emissions. This contributes to meeting IMO requirements and opens new possibilities for optimizing marine engine operation, improving their performance characteristics, and reducing negative environmental impact.