Failure Mechanisms Caused by Motor Oil Degradation and Their Study as Part of Expertise of Technical Condition of Gasoline Car Engines

Abstract

The article considers the main symptoms and causes of accelerated motor oil aging in the gasoline engine operation. This process is revealed when conducting auto-technical expertise and is caused by motor oil being exposed to various constructive and operational factors. The object of the study is the automotive internal combustion engine affected by fuel and motor oil that have abnormal properties. The goal of the work is to develop a method that can be used for the tasks of auto-technical expertise and can help clarify the types and symptoms of various effects on motor oil, as well as determine the causes for the changes in its properties when the engine is running. The research method is experimental-theoretical and includes the analysis of a large amount of data that were obtained during auto-technical expert research and demonstrated how various factors affect motor oil properties. To solve the problem, an algorithm for logical analysis has been developed that determine the nature of motor oil exposure to fuel. It describes the causal relationships between the failure event and the underlying events that initiate the change in oil properties. A logical graph is obtained for the analysis of causal relationships and determination of the failure cause due to lack of bearing lubrication that occurs as a result of oil exposure to fuel, which includes the formation of deposits, sediment, changes in oil viscosity. The practical application of the method is most expedient in the tasks of auto-technical expertise of engine faults. The obtained results help avoid gross errors in determining the cause of the formation of sediment in oil and/or deposits on the walls. Based on large factual material, it has been determined that the processes of oil exposure to fuel are random. However, attempts to obtain a mathematical description of the problem in order of assess the probability of this type of failure are complex and do not lead to any useful equations for practical application. In such conditions, the use of the developed logical algorithm becomes the most expedient, especially when determining the causes of engine failures, when they are caused by the use of abnormal fuel. KEYWORDS: INTERNAL COMBUSTION ENGINE, FUEL, OIL, DEGRADATION, FAILURE.

Application of logical methods in expert analysis of automotive engine failures in operation

“…The result obtained in the form of a logical graph (Figs. 6 and 7) clarifies and details the data [16] on the causes, signs and consequences of severe damage, associated mainly with breaking of the synchronization of progressively moving and rotating parts. In addition, this method is applicable for other tasks related to engine failures, for example, due to oil degradation [16].…”

“…6 and 7) clarifies and details the data [16] on the causes, signs and consequences of severe damage, associated mainly with breaking of the synchronization of progressively moving and rotating parts. In addition, this method is applicable for other tasks related to engine failures, for example, due to oil degradation [16]. In this case, unlike the severe damage considered, there can be no significant damage to the engine, and external signs usually indicate changes in oil properties.…”

“…4. Direct (a) and reverse (b) logical diagrams (direction of analysisbottom-up), describing data on a separately identified failure from amongst those given in [16] Based on such a logical scheme, it is not difficult to create a detailed graph for each failure considered.…”

“…Similarly, logical fault tree diagrams can be developed for other reasons under consideration [4,16,17,18], including destruction of the bearing and connecting rod due to lubrication failure (Fig. 7), valve destruction [14], abrasive wear and temperature damage.…”