Влияние износа плунжерных пар топливных насосов высокого давления на эксплуатационные показатели судовых дизелей

Представлен обзор авторских исследований повышения долговечности плунжерных пар топливных насосов высокого давления (ТНВД) судовых дизелей и влияния их износа на эксплуатационные показатели двигателей, выполненных с 1990 по 2020 г., Уточнены факторы, влияющие на ресурсные показатели плунжерных пар ТНВД судовых мало- и среднеоборотных двигателей. Определены методы и возможности оценки износных показателей топливной аппаратуры. Приведен сравнительный анализ ресурсных возможностей плунжерных пар, восстановленных различными методами, и новых пар, изготовленных ведущими дизелестроительными фирмами, а также анализ влияния износов плунжерных пар топливных насосов высокого давления на эксплуатационные показатели судовых дизелей. Показано, что по мере изнашивания плунжерных пар ТНВД судовых средне- и малооборотных дизелей уменьшается цикловая подача топлива вследствие его протечек, при этом возрастает температура отходящих газов, что часто приводит к аварийным ситуациям. Для повышения эффективности эксплуатации и надежности дизелей нами разработана перспективная технология упрочнения, позволяющая увеличить износостойкость плунжерных пар ТНВД. Впервые показано, что плунжерные пары ТНВД, восстановленные нанесением износостойких хромовых покрытий, успешно конкурируют с серийными (плунжерами без покрытия), а в случае нанесения композиционных покрытий (хром-металлокерамика) – обеспечивают значительно большую износостойкость. Динамическая гидроплотность пар и соответственно цикловая подача топлива плунжерных пар с износостойким покрытием плунжера остается практически неизменной в течение более длительного времени (период стабильной динамической гидроплотности в среднем в 2–3 раза дольше, чем для пар без покрытия). Ключевые слова: дизель, плунжерная пара, износ, отказ, цикловая подача топлива, температура отходящих газов, хром-металлокерамическое покрытие An overview of the author's studies focused on increasing the durability of plunger pairs of highpressure fuel pumps of marine diesel engines and the effect of their wear on engine performance is presented, made from 1990 to 2020. The factors affecting the resource indicators of the plunger pairs of high-pressure fuel pumps of marine low- and medium-speed engines have been clarified. Methods and possibilities for assessing wear indicators of fuel equipment are determined. A comparative analysis of the resource capabilities of plunger pairs, restored by various methods, and new pairs, manufactured by leading diesel-building companies, as well as an analysis of the effect of wear of plunger pairs of high-pressure fuel pumps on the performance of marine diesel engines is presented. It is shown that as the plunger pairs of high-pressure fuel pumps of marine medium- and low-speed diesel engines wear out, the cycle fuel supply decreases due to its leaks, while the temperature of the exhaust gases rises, which often leads to emergency situations. To increase the efficiency of operation and reliability of diesel engines, we have developed a promising hardening technology, which makes it possible to increase the wear resistance of the injection pump plunger pairs. It has been shown for the first time that high-pressure fuel pump plunger pairs, restored by applying wearresistant chromium coatings, successfully compete with serial (uncoated plungers), and in the case of applying composite coatings (chromium + cermet), they provide significantly higher wear resistance. The dynamic hydraulic density of the steam and, accordingly, the cyclic fuel supply of plunger pairs with a wear-resistant plunger coating remains practically unchanged for a longer time (the period of stable dynamic hydraulic density is on average 2–3 times longer than for uncoated steam). The conditions of operation of precision parts of the fuel equipment of marine low and medium speed engines are described. The factors influencing the service life of the plunger pairs are given. Methods and possibilities for assessing the wear indicators of fuel equipment are determined. Keywords: diesel, plunger pair, wear, failure, cyclic fuel supply, exhaust gas temperature, cover

Method of calculating pneumatic compensators for plunger pumps with submersible drive

One of the most promising ways to improve the efficiency of mechanized oil production is a plunger pump with a submersible drive, which allows obtaining harmonic reciprocating movement of the plunger. In the pumping process of well products by plunger pumps, oscillations in the velocity and pressure of the liquid in the lifting pipes occur, which lead to an increase in cyclic variable loads on the plunger, a decrease in the drive life period and the efficiency of the pumping unit. To eliminate the pulsation characteristics of the plunger pump and increase the reliability indicators of the pumping unit (in particular, the overhaul period), pneumatic compensators can be used. A method for calculating the optimal technological parameters of a system of deep pneumatic compensators for plunger pumping units with a submersible drive, based on mathematical modeling of hydrodynamic processes in pipes, has been developed. Calculations of the forming flow velocity and pressure in the lifting pipes of submersible plunger units equipped with pneumatic compensators (PC) have been carried out. Influence of the PC technological parameters on the efficiency of smoothing the oscillations of velocity and pressure in the pipes has been analyzed. Non-linear influence of the charging pressure and PC total volume on the efficiency of their work has been established. Optimal pressure of PC charging, corresponding to the minimum pressure in the tubing during the pumping cycle for the considered section of the tubing, is substantiated. Two ultimate options of PC system placement along the lifting pipes are considered. In the first option, PC are placed sequentially directly at the outlet of the plunger pump, in the second - evenly along the lift. It is shown that the first option provides the minimum amplitude of pressure oscillations at the lower end of the tubing and, accordingly, variable loads on the pump plunger. Nature of the pressure and flow velocity oscillations in the tubing at the wellhead for both options of PC placement has similar values.

Regulation of the three-plunger pump operation

Analytical dependences are proposed for recalculating the operating parameters of three-plunger pumps when changing the rotation frequency of a crankshaft. Keywords three-plunger pump, plunger diameter, nominal pressure, rotation frequency, crankshaft. [email protected]

Ensuring Reliable Operation of Machine Parts with a New System of Variable Tolerances

Introduction. The article describes an algorithm for determining the system of tolerances for ensuring reliable operation of parts on the section. The block diagram of the program for determining the variable tolerances is demonstrated. There determined blocks of initial information − broken and smooth curves of the controlled parameter, histogram and graph of resource distribution and definition of active area of control, and blocks of building graphs of “marginal fan curves of wear” and systems of admissions for objects of study of two types: for universal fuel pump (UTN-5) and four-section small-sized fuel pump with mechanical regulator. Two ways of determining the system of tolerances are suggested. Variant 1 is a graphical way through constructing “limit fan curves of wear” and determining tolerances by the value of ordinates in the control points. Variant 2 is an analytical way. There is created a formula to replace the graphical method for determining system tolerances. Materials and Methods. Two models of high-pressure pump were selected as objects of the study. Nominal and limit values of parameters were known for the pumps. Schedules for checking and equation of wear curves are determined. Dependencies describing the pump plunger pair wear curves are determined. A histogram and graph for determining pump life cycles are drawn. The active area of control is determined with a given failure probability coefficient. Results. As a result of the study the values for the tolerances system of two types of high pressure fuel pumps are obtained. Reliability values for one pump type are determined. Graphic and analytical algorithms for determining the system of tolerances by the formula are developed. Discussion and Conclusion. The study approves the possibility of using the variable tolerance as a basis for determining the system of tolerances and reliability indicators of the diagnostic object.

Development of a magnetostrictive material–based electro-hydrostatic actuator with an active rotary rectifying valve

A magnetostrictive material–based electro-hydrostatic actuator with an active rotary valve for fluid rectification is presented in this article, which consists of a magnetostrictive material–based pump, an active rotary valve and a hydraulic cylinder. First, the magnetostrictive material–based pump plunger motion model is established, and the factors that affect the phase lag between the magnetostrictive material–based pump plunger displacement and the input voltage are discussed. Second, the flow area model of the active rotary valve and the kinetic model of the cylinder are established. After that, the phase compensation for the input voltage that influences the synchronous motion between the magnetostrictive material–based pump plunger and the valve spool is investigated. Finally, the simulation model is built in MATLAB/Simulink, and the results are subsequently verified with experimental data. The results indicate that the phase lag of magnetostrictive material–based pump plunger output displacement is mostly influenced by magnetization with a low driving frequency and by an eddy current with a high driving frequency. The compensation angle for the input voltage affects the output flow of the magnetostrictive material–based electro-hydrostatic actuator and the moving direction of the cylinder piston rod. For a magnetostrictive material–based electro-hydrostatic actuator rectified by the active rotary valve, at the driving frequency of 200 Hz, the peak output flow can reach 2.4 L/min, which is much higher than 1.1 L/min of a magnetostrictive material–based electro-hydrostatic actuator rectified by the passive reed valve.

Optimizing the Quantity of Diesel Fuel Injection by Using 25HHOCNG Gas Fuel Mixture

Injection behaviors of internal combustion engines are very substantial fact that provides developments to future strategies about optimizing the engine and fuel parameters. During the combustion process, pilot diesel injection technique is more preferable option while using alternative gas fuels in a diesel engine. In this experimental study, a 3.6 L commercial, four stroke, four cylinders and mechanical fuel pump non-modified diesel test engine operated with hydroxy (HHO) and compressed natural gas (CNG) fuel mixtures under 25% and 75% (vol/vol), respectively. Diesel fuel injection quantities were reduced with the help of steeping motor devices which mounted on mechanical fuel pump plunger pin. Sensitive removes of steeping motor, plunger pin twisted clockwise 360°, 720° and 1080°, respectively. Comparisons of engine performance and exhaust emissions were explained briefly and illustrated via graphs. As a result, 720° clockwise twisted pin is the optimum point for experimental fuel pump plunger while using 25HHOCNG fuel mixtures.

Experimental Study on the Performance of the Engine Fueled with DME-Methanol Blends

Performance test of the engine fueled with DME-methanol blends was conducted on a 4102BQ diesel engine. The results show that: by increasing the fuel pump plunger diameter, delaying injection timing, and reducing nozzle-opening pressure, the rated power of the engine, fueled with DM90 blends (Mass ratio of DME and methanol is 9:1), descended 13.97% relative to the original diesel engine, but the soot emissions did not appeared in all test conditions. In full load condition, NOx emissions declined by 55.1%, CO emissions fell by 65.8%, but HC emissions increased by 21.6%.