Study on the leakage of plunger pair under static condition in high-pressure common rail injector considering deformation effect

Plunger pair is the key component of high pressure common rail injector and its sealing performance is very important. Therefore, it is of great significance to study the leakage mechanism of plunger pair. Under static condition, the high-pressure fuel flow in the gap of the plunger pair caused the deformation of the plunger pair structure and the temperature rise of fuel. For a more comprehensive and accurate study, the effect of deformation, including elastic deformation and thermal expansion, the physical properties of fuel, including density, viscosity and specific heat capacity, as well as the influence of plunger posture in the plunger sleeve, including concentric, eccentric, and inclination condition, are considered in this paper. Firstly, the mathematical models including Reynolds equation, film thickness equation, non-isothermal flow equation, parametric equation of fuel physical property, and section velocity equation are established. The numerical analysis based on finite difference method for the solution of these models is given, which can simultaneously solve for the fuel film pressure distribution, temperature distribution, thickness distribution, distribution of fuel physical properties, and leakage rate. The models are validated by comparing the calculated leakage rates with the measurements. The effects under different posture of plunger are discussed too. Some of the conclusions provided good guidance for the design of high-pressure common rail injector.

INFLUENCE OF WORKING FLUID VISCOSITY ON LUBRICATION MODE OF HYDRAULIC UNITS OF CONSTRUCTION MACHINES

The influence of dynamic viscosity of working liquids И-20А, МГЕ-46В, ВМГЗ on the lubrication of plunger pairs of axial-piston pumps of construction equipment is considered in the article. Based on the existing classification of lubricant types, a mathematical model is obtained to determine the effective viscosity, which corresponds to the transition of the plunger pair from the boundary lubrication regime to the semi-liquid mode. The obtained model takes into account the geometric parameters, the speed of rotation of the pump shaft and the size of the dimensionless criterion — the relative thickness of the lubricating film. The calculation of the change in the effective viscosity from the angle of rotation of the shaft for a plunger pair of an axial-piston pump with an inclined disk.

Increasing the life of plunger and barrel assembly of high pressure fuel pumps

In order to identify the regularities of further increasing the efficiency of transport and technological machines, it is of interest to consider the issues of determining the impact of their design and technological parameters on the quality of running-in and the operability of fuel pumps. The article analyzes the influence of the initial operating modes and the lubricating medium on the quality of running-in and subsequent performance of high-pressure fuel pumps. On the basis of theoretical studies, equations were obtained to determine the unbalanced radial force acting on the plunger and fuel leaks in the plunger pair. These expressions make it possible to establish the dependence of the specific pressure in the plunger and barrel assembly both on the design and technological parameters of the pump.

Diagnostics of hydraulic density of plunger couple of tractor diesel

The article considers the process of developing diagnostic mathematical models that take into account the influence of the hydraulic density of the plunger pair associated with wear. To estimate leaks of precision parts, methods for calculating the cycle feed for wear of plunger pairs are presented. The position of the cut-off edge relative to the hole changes due to the injection movement and rotation of the plunger during the regulation of the fuel cycle. The method and results of accelerated testing of plunger pairs are also presented.

Optimization of capital repair of rod pumps by advanced technologies

The designs of rod pumps, produced by domestic factories, have a significant repair resource. It allows us to make repeatedly a deep overhaul of the plunger pair with usage of advanced technologies. This technologies include mechanical treatment of deep holes (cylinder rod pump L = 3 m or more); thermochemical treatment of the cylinder in shaft furnaces in a carbon dioxide environment; hot spraying with wear-resistant powder grade PRNH16SRZ. Application of the above-mentioned advanced technologies during overhaul of rod pump allows optimizing the costs of its repair, increasing the service life and getting the pump after overhaul with the same technical parameters, and even higher, when compared with new designs.

RESEARCH OF WEAR OF PLUNGERS AND BUSHINGS OF THE FUEL PUMP OF THE DIESEL ENGINE

Compliance with the requirements of the new international standards for diesel fuel (for example, reduction of sulfur compound content) poses a new problem: the lubricating properties of the fuel deteriorate. The experience of the use of highly purified fuels in a number of countries of Western Europe and the United States showed that the reduction of harmful substances in the exhaust gases is accompanied by premature failure of precision pairs of fuel equipment, including plunger pairs of high-pressure fuel pumps, as a result of power losses, increased fuel consumption, increased fluidity of exhaust gases. To solve the problem of wear of the structural pair "plunger-bushing" in this work, the problem of studying the physical and mechanical process of wear of their contacting surfaces from the standpoint of fatigue wear theory is set and solved. The stochastic nature of the destruction of micro-volumes occurring on the contacting surfaces of the plunger pair in the micro-and macro-levels, the influence of temperature gradients make it difficult to obtain a complete mathematical description of the main processes affecting the mechanism and the intensity of their wear. The absence of equations that reflect the relationship of all factors affecting the wear process, it is advisable to use the analysis of the dimension of the physical quantities characterizing the friction and wear of parts for the modeling process. The empirical experience of the science of friction and wear allows us to imagine the influence of certain factors on the process under study. Due to the lack of the possibility of mathematical description of the influence of all factors on the process of wear of the plunger pair, the method of the theory of analysis of dimensions is used. As a result, the criterion relations are obtained, allowing judging the qualitative relationship of the parameters of the acting factors.

ANALYTICAL ESTIMATION OF THE TECHNICAL CONDITION OF PLUNGER PAIR WHEN COMPLETED BY HYDRODENSITY

The paper considers the factors influencing the estimated indicator of the technical state of the plunger pairs, when they are equipped according to the hydrodensity. To determine the influence of factors on the estimated value of the plunger pair in terms of hydrodensity, a two-factor experiment was planned and implemented, and a mathematical model was obtained for the process of selecting plunger pairs as a set for hydro-densities. On the basis of the research, it is suggested to complete the plunger pairs as a set on the KI-759 device with a mathematical dependence to reduce the error.