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The article provides the study on causes of damage to ICE intake valves, in the course of which the intake valve heads have been overheated and deformed as a result of material creep. On the example of the failure detected in the analysed engine, it has been established that the traditionally known reasons such as the combustion process failure cannot cause the damage described. For the purpose of determining the real causes of damage to the intake valves the authors simulated the thermal state of the intake valve in the heatingcooling conditions with the impact of gas in the cylinder and the impact of air in the intake pipe as well as the contact heat exchange with the seat with regard to thermal conductivity along the stem. The calculations have shown that with the increase of rotation frequency the failure of the control system that causes the engine to run at high rotation frequencies with a small intake valve lift leads to the temperature increase higher than it is recommended for the materials used, which causes the described overheating. Based on the conducted research the authors have developed recommendations for improving the reliability of the intake valves performance in the ICEs with variable valve timing. [ABSTRACT FROM AUTHOR]

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The sealing problem of flash vaporization equipment interferes with the flash evaporation process and reduces flash evaporation equipment's operating efficiency, wasting energy. This issue has not been given sufficient attention. The influence of air inflow rate on low-pressure static flash evaporation is studied by adding an intake valve on the flash chamber in experiments. The suitable adjustment ranges of the intake and extraction valves' opening levels are determined through experiments. By analyzing the effects of different initial back pressures and initial liquid temperatures on the flash process, the relationship between the dimensionless evaporation efficiency and the dimensionless rate of pressure rise caused by the air inflow is proposed. • The opening level of the extraction valve affects the flash duration. • The effect of intake valve opening is more sensitive to initial back pressure. • The relation between the rate of pressure rises and the vapor productions is linear. • The relationship between m e ‾ and v p ‾ is proposed as: m e ‾ = − 10 − 2 × P 0 ‾ v p ‾ + 7.4 × 10 − 5 ψ. [ABSTRACT FROM AUTHOR]

The degradation of engine oil and its influence on the formation of intake valve deposits is being discussed in this paper. Degraded samples of oil were prepared using a stationary engine testbed while deposition studies were performed using a bench top simulator. The degree of degradation, as indicated by the amount of polymeric, oxidized and oxidative products, increases as the engine oil is used over a period of time. The rate of degradation, however, varies depending on the quality of base oil and the type of additives used. It was obser ved that the degraded oil played an important role in the formation of inlet valve deposits. [ABSTRACT FROM AUTHOR]