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The wear analysis is a basic step for assessment of the functioning of mechanical systems and helps to the products improvement. The service life of the assemblies is approximate depending on the level of wear of their components. Starting from the product prototype phase, all components are tested and very carefully analyzed. This kind of analysis depends on the fault type and also the analysis devices are chosen in view of this. The Scanning Electron Microscope is one of the most used equipment which provides images with very good resolution at nanometers sizes. The classic microscopes are very often used for surface analysis or measurements. Hardness tester and adhesion measurements devices help to evaluate the material hardness and coatings adhesion. The improvement of the wear analysis methods is necessary due to continuing evolution of the materials and production processes. This paper presents the most common wear types from the injection high-pressure pumps and their analysis methods.

The wear is a very common physical phenomenon in the mechanical area. It can be observed in different mechanisms in different forms. Depending of the role of the mechanism in the assembly or subassembly of which it is part of, wear can happen. Thus, after a short analysis in the automotive area, it can be observed that in the fuel high pressure pumps, several forms of wear are encountered. Various levels of the wear can be studied. Depending of the working period and the operating conditions of the pump, various types of wear can occur, such as adhesion, corrosion, abrasion, fatigue or erosion. The purpose of this paper is to experimental study a type of wear often encountered in high pressure pumps, whose early identification can be useful in damages prevention in order to assure the pump performance. Some wear examples due to material fractures are described.

The article describes the impact of hydrogen-containing vegetable fuels consumption with modern injection apparatus. The fuel in question is B100 rapeseed oil ethyl ester. The process of atomizing fuel in the engine at high temperature and in a high pressure chamber plays an important role in the combustion processes in the CI engine. The elements responsible for supplying fuel to the engine’s combustion chamber are the injectors and the injection pump. The paper presents the construction and operation of modern injection pumps and fuel injectors, the methods of their diagnosis are discussed, the important role of precision, and the course of their wear phenomenon are indicated. The paper discusses the impact of hydrogen-containing “green” vegetable fuels on the durability and reliability of injection pumps and fuel injectors used in Common Rail systems. In addition, the tests on the operating parameters of the fuel injector and pump operating on conventional fuel and hydrogen-containing “green” biofuel were carried out.

The article presents a concept of improving operation of the engine with the effect of gas desorption from a solution with nucleation of gas bubbles. This concept consists in dissolving gas in diesel fuel until the solution is in equilibrium. At a later stage, the phenomenon is reversed, and the gas is released from the solution during its injection into the combustion chamber. The purpose of the study is to present the idea of the desorption effect along with a thermodynamic analysis of the process and to study its impact on the operation of a diesel engine. The article also describes the most important features of the injection pump adapted to employ the desorption effect, which is a proprietary, patented solution. The conducted engine preliminary tests concerned the most important parameters of the engine’s operation (indicated pressure course, pressure growth rate, heat release rate, etc.) and the emission of harmful compounds (PM—particulate matter, CO, HC, and NOx—nitrogen oxides). A significant reduction of PM, CO, and HC, with a simultaneous increase in NOx emissions obtained in tests, confirmed that the desorption effect facilitated engine operation.

In this study, in order to improve the performance of the plunger type high pressure pump using DME as fuel, the flow verification was confirmed according to the change of the pump rotation speed and the design parameter change of the high pressure pump through experiments and analysis. In the experiment, the commonrail pressure was fixed at 300 bar and 400 bar, and the speed of the pump was increased from 300 to 1,000 rpm. By using AMESim, the discharge flow rate was compared and verified by changing key parameters. As a result of experiment, the discharge flow rate increased linearly as the number of revolutions was increased. Also, as the pressure of the common rail increased, the flow rate of the pump decreased slightly. As the result of simulation, it was confirmed that both the discharge flow rate and the internal pressure had the same results as in the experiment and found the two key parameters can affect to the pump performance.

The slurry abrasive water jet (S-AWJ) has the advantages of high cutting capacity and simple implementation process. However, the high-pressure slurry abrasive flow generated by pump pressurization causes severe wear on the key passage parts of the pump: the T-tube, valve ball, and valve seat. Therefore, it is significant to study the wear laws and wear mechanisms of high-pressure slurry abrasive flow on these parts. In this paper, firstly, a finite element model was established using Fluent to study the wear law of flow passage parts with different parameters. Secondly, a wear test device was designed and the wear tests were conducted. It was found that the wear rate of the valve ball, valve seat, and T-tube increased with the increase in pump pressure and abrasive concentration and decreased with the increase in abrasive mesh number. Moreover, the wear morphology of the wearing parts was also studied. The surface morphology of the valve ball after wear was mainly lip-shaped pits. The wear position of the valve seat was the chamfer in contact with the valve ball. The main reason for the wear was that the abrasive would accumulate after the contact area changes from the linear sealing to the face sealing. The wear morphology of the T-tube was mainly flaky and dotted craters. Finally, the sensitivity of the wearing parts to different parameters was obtained by orthogonal tests, and the wear model for wearing parts was established. The results of this paper provide a basis for a closer understanding of the wear mechanism of the S-AWJ pump body, as well as future wear reduction solutions.

Most high-pressure fuel pumps for compression-ignition engines manufactured today are cam driven. These pumps have numerous advantages, such as low energy consumption and limited production costs. However, a problem arising from the nature of the cam mechanism is an unfavorable distribution of forces in the camshaft-plunger-cylinder system of a delivery section. The authors have proposed an innovative pump design that eliminates most of the problems present in conventional solutions. The pump utilizes a gear-based hypocycloid drive. This paper focuses mainly on the strength analysis of the two critical components (countershaft and mount) of the subassembly under the highest load – simulations were carried out for different critical load states. The following procedure of estimating fatigue life was adopted for computations: the operational evolution of stresses will be systematized to the set of amplitude stresses and mean stresses by means of the “Rainflow” method. The results obtained in the work showed that the main factor determining change of stresses was the presence of clearances in the pump mechanism. It has been proved that the values of clearances have a negative influence on the power transmission in particular – their presence results in loads being carried by the countershaft and not by the support inter-operating with it. This may cause frictional wear of teeth, leading to the improper operation of the transmission. The analysis showed that the mount was designed correctly. This facilitates the use of less demanding constructional materials.

The roller–shoe mechanism is a classic mechanical assembly with an essential role in motion transmission. Common rail high-pressure pumps are an example of a complex assembly that uses such a mechanism to transform the rotation motion into a translation one. The rolling element of the mechanism is represented by a cylindrical roller. Although it can carry heavy loads due to its design, a proper surface profile could significantly increase the life of the entire mechanism. A better solution can be achieved using a logarithmic profile. The shoe is the second base element of the mechanism. It is a part with an inner cylindrical surface and it is separated from the roller by a thin lubricant film. Considering this, increasing the hardness of the roller–shoe contact surface can be obtained using a suitable coating. The positive results of this coating are highlighted using endurance tests to which high-pressure pumps are subjected. Therefore, the roller profile and the shoe coating represent two directions for improving the contact between the mechanism transmission elements, in terms of wear reduction. The purpose of this paper is to identify a suitable roller profile and to highlight its impact on the shoe coating.

A study on the internal fluid dynamic of a high-pressure external gear pump is described in this paper. The pump has been analyzed with both numerical and experimental techniques. Starting from a geometry of the pump, a three-dimensional computational fluid dynamics (CFD) model has been built up using the commercial code PumpLinx®. All leakages have been taken into account in order to estimate the volumetric efficiency of the pump. Then the pump has been tested on a test bench of Casappa S.p.A. Model results like the volumetric efficiency, absorbed torque, and outlet pressure ripple have been compared with the experimental data. The model has demonstrated the ability to predict with good accuracy the performance of the real pump. The CFD model has been also used to evaluate the effect on the pump performance of clearances in the meshing area. With the validated model the pressure inside the chambers of both driving and driven gears have been studied underlining cavitation in meshing fluid volume of the pump. For this reason, the model has been implemented in order to predict the cavitation phenomena. The analysis has allowed the detection of cavitating areas, especially at high rotation speeds and delivery pressure. Isosurfaces of the fluid volume have been colored as a function of the total gas fraction to underline where the cavitation occurs.

Safflower (Carthamus tinctorius L.) is an underestimated and multipurpose crop resistant to environmental stresses. Its oil presents useful chemical–physical properties, potentially exploitable for industrial purposes as a bio-based lubricant. In this work safflower oil was applied as a less toxic alternative to mineral-based hydraulic fluids. The extracted oil was partially refined and the antioxidant tert-buthylhydroquinone (THBQ) was added at two concentrations (0.25 and 3.00 mg kg−1). Efficiency tests of the obtained oil were carried out using an experimental test rig capable of simulating a real hydraulic system and performing severe short-duration work cycles with the aim of strongly accelerating the ageing of the tested oil. Oil performance was verified by monitoring hydraulic and chemical–physical parameters, which were correlated to the main lubricant properties through sensor detection and laboratory analysis in parallel. The results indicated that the safflower oil behaved well at both THBQ concentrations and showed good technical performance (operating pressure and temperature; flowrate and transmitted hydraulic power), though a higher THBQ concentration was necessary to protect the oil’s chemical–physical properties from worsening. In fact, the higher THBQ concentration allowed the test to be extended to 270 h, an improvement compared to the 150 h that was achieved with the lower THBQ concentration. Finally, the use of safflower oil for industrial and agricultural purposes seems feasible and would contribute toward the sustainability of the whole crop rotation in a prospective valuable circular economy.