Vol 10, No 2 (2016)
- Year: 2016
- Articles: 13
- URL: https://journal-vniispk.ru/2074-0530/issue/view/3714
Articles
The method of simulating the loading of boosted diesel engine during start-up at low ambient temperatures
Abstract
The paper discusses the method of simulating the loading of boosted diesel engine during start-up at low ambient temperatures. To improve the reliability of the experimental evaluation of the results of diesel qualities the device simulating resistance to crankshaft turn over from the side of transmission elements of object was developed. The device provides the ability to control and change the moment of resistance to crankshaft turn over. The method of start-up testing of high performance engine with the device in a climatic chamber was developed. The engine is equipped with prior-start preparation and start-up facilitation systems. Loading parameters for type 12ChN15/16 engine object. In accordance with the test program 20 experiments were conducted at ambient temperatures of 5, minus 5 and minus 20 °С. The results of experimental studies confirmed the effectiveness and adequacy of the proposed method. It was revealed that crankshaft breakaway torque during engine acceleration does not depend on load of engine and oil viscosity (in the range of ambient temperatures during testing) and is determined by moment of inertia of the rotating masses. During diesel turn over load pressure is provided almost simultaneously with the start of engine crankshaft breakaway. Loading of device pump by pressure of 14 MPa leads to an increase of resistance to crankshaft turn over moment at an ambient temperature of minus 20 °С to 9% (from 883 to 970 N·m). According to the results of testing the recommendations for further improvement of the device to simulate loading of boosted diesel engine during start-up at low ambient temperatures were given.
Izvestiya MGTU MAMI. 2016;10(2):2-7
2-7
Innovative developments in the field of intensification of fuel-air mixtures ignition
Abstract
The article discusses the intensification of fuel-air mixtures ignition in internal combustion engines with positive ignition. The conditions of operation of the spark plug in the combustion chamber and directions of improving fuel-air mixtures ignition process organization were considered. It was noted that nowadays spark ignition is used widely and it performs one of the basic functions in internal combustion engine, but reserves for its improving are almost exhausted. In this context, a promising direction in the field of intensification of lean mixtures combustion in the engine through the use of laser ignition system is considered. The article describes the design of the laser adapter plug installed in the spark plug hole of engine cylinder head. It is shown that the intensification of combustion of lean mixtures in the internal combustion engine through the use of laser ignition system significantly improves the process of primary focus ignition, which contributes to the rapid development of the ignition and subsequent combustion process. And engine with positive ignition performance characteristics significantly improves. The advantage of laser ignition is the ability to focus the beam on a small area in the center of combustion chamber to ensure optimal combustion conditions. It was noted that during ignition firstly the maximum temperature is reached and then it drops. It is shown that during the spark ignition it largely determines the speed of ignition and combustion, but when laser ignition is used it has practically no influence on the ignition and subsequent combustion of the mixture. There are also other advantages of the laser ignition in relation to the traditional ignition, the most important are: the possibility of reducing the requirements for octane level and ensuring stability and reliability of the engine when operating on poor mixtures.
Izvestiya MGTU MAMI. 2016;10(2):8-12
8-12
Mathematical modeling of cargo oscillations on the mobile machine manipulator load lifting body
Abstract
Hydraulic crane-manipulator devices mounted on a movable chassis of different transport and technological machines are widely used in various sectors of the Russian economy. The main objective of handling system operation is movement of cargo or working body to the desired point of space. Therefore, dynamic loading of handling system is largely determined by the nature of the interaction with cargo or working body. The paper discusses approaches to assessing the impact of cargo on loadbearing metal structure of mobile machine manipulator. The mathematical models of cargo oscillations on rigid and flexible fixture are developed. Motion equations are integrated together with motion equations of handling system. Dynamic model of cargo oscillations on rigid and flexible fixture are considered. The results of mathematical modeling of cargo oscillations on rigid and flexible fixture are provided. Stiffness of handling system was determined using the finite element method. Mathematical modeling helped to find out that cargo oscillations on load lifting body cause additional dynamic loading on loadbearing metal structure of mobile machine manipulator. For jib cranes dynamic factor when determining dynamics of cargo impact is usually taken equal to 1.1 ... 1.3, and on the basis of the calculations the dynamic factors when using flexible fixture can reach values of 1.5 ... 2.0. Therefore, in the calculation of impacts from the side of cargo it is recommended to use the developed model. Dynamic loads for rigid fixture are lower than when using flexible cargo fixture. Dynamic factor in this case lies in the range of 1.05 ... 1.1.
Izvestiya MGTU MAMI. 2016;10(2):13-19
13-19
Mathematical model of test bench
Abstract
The description of multifunctional test bench construction to determine the basic operational characteristics of transmissions of automobiles and trucks designed in Volgograd State Technical University is provided. The description of its mathematical model created on the basis of the spatial dynamic schema is given and the results of calculation of test bench mass and inertia parameters are provided. The models of moving masses are the masses of transmission rotating elements, which transmit torque, transmission housing, test bench frame, that consists of two subframes, two hubs, DinaPack loading device, including a hydraulic machine. The values of parts inertia moments and stiffness of its joints are obtained by DASP software package and SolidWorks 3D CAD system. On the first stage to carry out the simulation capabilities at various loading conditions and forecast their results without a long-term field tests, on the basis of the structural scheme of test bench the flat dynamic model was created, which besides the data on composition and communication of the masses, contains data on elastic, inertial and dissipative parameters of its elements. On the next stage the spatial structural test bench scheme was created, on the basis of which in “Universal mechanism” program the spatial dynamic model was made. The dynamic model of test bench includes 31 inertial masses influenced by linear, contact, bipolar and special forces. To check the adequacy of the created model at the initial stage the calculation of fundamental frequencies of its masses in the range from 0 to 10000 Hz was made. The comparison of its values with the results of processing of experimental digital oscillograms of test bench masses oscillations showed sufficient for the solution of engineering problems convergence of results.
Izvestiya MGTU MAMI. 2016;10(2):20-25
20-25
Experimental study of polymer coatings quality of tractor and automobiles body parts from the elastomer F-40 solution with infrared drying
Abstract
Infrared drying of automotive coatings is quite widely used in painting. However, the infrared heat treatment of the coatings from elastomer F-40 solution is not studied. The article presents the method and results of experimental studies of defects in coatings for tractors and automobiles body parts from the elastomer F-40 solution with different methods of drying, deformation and strength properties of the elastomer F-40 from the infrared operation mode, and the optimum mode is provided. Price of body parts components and assemblies for tractors and automobiles is much higher than the price of other typical parts and largely forms the price of units and machines in general. These items are basic, resource details, which mainly determine lifetime of the entire unit. One major reason of body parts rejection is mounting bores wear due to fretting corrosion. Polymer coating on the surface of the holes can significantly increase tolerance when boring holes in the process of production of new body parts and also increase the resource of bearings fixed joints and eliminate the occurrence of fretting corrosion. The use of thermoradiation drying method of coatings on the basis of elastomers allows to reduce defects in the coating in 1.43 times compared to the convective process. The paper defined the optimal mode of infrared drying of elastomer films F-40 (temperature , time ). It is found out that infrared drying comparing to convection method provides increase of material strength in 1.42 times, reduction of thermal treatment temperature in 20оС, of time in 1hr, which confirms the reduction of energy consumption.
Izvestiya MGTU MAMI. 2016;10(2):26-31
26-31
Rubber-reinforced caterpillar tracks of agricultural tractors. Stiffness at tension and bending
Abstract
The theoretical and experimental study of tensile stiffness and bending strength of rubber-reinforced caterpillar traclks of agricultural tractors is provided with the development of design models and analytical expressions and the assessment of their reliability. The discrepancy between the results of calculations of rubber-reinforced caterpillar tracks rigidity obtained by analytic expressions and experimental data does not exceed 3%, which confirms the possibility of the use of design models and analytical expressions in practical calculations. The effect of design of the power layer and the presence of damage at rubber-reinforced caterpillar tracks on stiffness indicators in tension and bending was experimentally evaluated. On the basis of experimental studies of rubber-reinforced caterpillar tracks was discovered that that the difference between the values of tensile stiffness of entire samples and damaged parts with cable structure is 10.44% and for cord design samples - 10.78%. This proves a minor impact of damage presence in the form of transverse cracks on caterpillar track stiffness value in tension (in the absence of bundles). The negligible effect of rubber-reinforced caterpillar tracks power layer design on the value of its tensile stiffness (when supporting capability of the considered power layers is constant) and significant influence of damage presence in the form of transverse cracks on the bending stiffness value of rubber-reinforced caterpillars were determined. Difference between the values of bending stiffness of entire samples and damaged parts of rubber-reinforced caterpillar tracks is 41,1 % for parts with cable structure and 22,9 % for cord design samples. This proves a major impact of damage presence in the form of transverse cracks on caterpillar track bending stiffness value.
Izvestiya MGTU MAMI. 2016;10(2):32-38
32-38
The transport robot with reconfigurable structure
Abstract
The paper discusses research results of transport robot new design for automation of different kinds of work in emergency situations. The purpose of research is to expand the robot's functional properties due to the possibility of overcoming the various obstacles, as well as high-speed movement on flat surfaces by reconfiguring its structure to the type of surface displacement. The robot has two caterpillar tracks located on each side of the platform for process equipment and two wheeled driving machines mounted on the front and rear of platform between caterpillar track groups. A feature of the design is that the wheel axis of wheeled driving machines is connected with the platform through levers, which drive is located on platform with the possibility of wheeled driving machines movement vertically relative to platform. Lever length could vary that allows to transform robot for different obstacles. A kinematic model of the robot in SolidWorks was developed to study different traffic modes. An experimental sample remote-controlled robot on the basis of standard components nodes was made. Its laboratory tests confirmed the ability to overcome different types of obstacles. The simulation of control system for levers extension in Matlab Simulink was made. It showed the stability of the system at the given parameters. The results can be used to create full-scale robots.
Izvestiya MGTU MAMI. 2016;10(2):39-45
39-45
Integrated vehicle safety
Abstract
The paper analyzes issues of vehicle structural safety regulated by international UN rules in order to reduce the number of road accidents and particularly the severity of their consequences. The effectiveness of the UN Rules for reduction of road accidents is analyzed and especially the number of killed and injured in accidents on the roads is studied. There were also considered the issues related to the increasing pollution of the atmosphere of large cities with exhaust gases harmful emissions from road transport even though long-term efforts of manufacturers were made to drastically reduce them to the Euro 6 for Ecology UN Rules number 49 and 83. A comparative analysis of foreign and domestic studies of emissions from wear of tires, brake mechanisms of road transport and road surface was made. The conclusion of a significant increase in pollution of air environment of large cities because of the solid fine particles from wear of tires and road surface was made. The problems of active, passive and environmental safety predetermine the necessity of reconsideration of the concept and strategy of the international and national legislation, for integrated safety of road transport.
Izvestiya MGTU MAMI. 2016;10(2):46-54
46-54
Overview and classification of advanced schemes of multithreaded combined energy transmissions based on their kinematic analysis
Abstract
The article deals with the existing and promising modern automotive multithreaded combined energy transmissions, based on the principle of separation of power for the electrical and mechanical streams. These combined energy transmissions due to the presence in their design of continuously variable electric transmission allow obtaining an arbitrary gear ratio from the engine to the wheels, while maintaining high efficiency inherent to manual transmission. It allows to assume that multithreaded combined energy transmissions are promising for use in hybrid vehicles as evidenced by the successful operation of Toyota Prius automobile. The article describes 16 different schemes of electromechanical transmissions. Some of them are actually applied in practice, while others exist only as prototypes or theoretical projects. On the basis of the kinematic analysis, including determination of number of operating modes and degrees of freedom as well as the construction of kinematic plans for different of operating modes the classification of multithreaded combined energy transmissions by type of differential mechanism (mechanical part of transmission) was proposed. There were allocated single-mode and multi-mode multithreaded combined energy transmissions. The last ones were divided into three classes, depending on the method of obtaining different modes: stepped, variable and combined. Moreover, within each class transmissions with differential at input, differential at output with complex power division were identified. This review allows to get acquainted with possibilities of application of multithreaded combined energy transmissions in road transport, to understand its strengths and weaknesses, identify promising areas of application of multithreaded electromechanical transmissions of various types.
Izvestiya MGTU MAMI. 2016;10(2):55-65
55-65
Proposals for the formulation of law of control for articulated truck activated trailer hydrostatic transmission
Abstract
The article is devoted to the development of scientifically based methods of creation of systems of automated adaptive control (SAAC) by “intelligent” transmissions multidrive-wheeled vehicles, such as articulated trucks with activated trailing links. The purpose of the studies is to formulate laws of control, the use of which in such SAAC should provide automatic selection in a variety of driving conditions of energy-efficient mode of power distribution between drive wheels. One of the most important issues in this case is to determine the parameters with necessary information content, which control of changes’ nature in the process of vehicle motion will allow SAAC to form control signals, ensuring keeping of the energy-optimal mode of motion in changing conditions. Obviously, these parameters should be the only ones that can be controlled during motion of articulated truck in real operation conditions by currently known and reliable methods. The article contains the results of this research obtained on the basis of the mathematical modeling of steady linear motion of articulated truck with activated trailing link, which wheels’ drive is provided by adjustable hydrostatic transmission in conditions of non-deformable bearing surface. The analysis was performed in the range of change gear ratios of trailer wheel drive when the transmission does not have interaxle power circulation. On the basis of studies the authors revealed the parameters that meet the above mentioned requirements, and also present the proposals for the formulation of control law for hydrostatic transmission of articulated truck activated trailer unit, which usage in the developed SAAC will improve energy efficiency of articulated trucks.
Izvestiya MGTU MAMI. 2016;10(2):66-76
66-76
Analysis of the structure of a mathematical model of a piston engine cycle
Abstract
The paper analyzes the structure of the mathematical model of a piston engine cycle and proposes a modified version of it, allowing determination of the optimum pressure p in the cylinder. For the analysis the authors used published results of other authors’ studies of work processes for piston engines, working on liquid fuels, and gave recommendations on usage of models for calculation and development of engines. In the considered mathematical model there are used cycle equations of: thermodynamic processes, energy balance, mass conservation, state and known empirical relationships. It is shown that four factors have major impact on changes of pressures p: current volume of the cylinder V; mass of the working body at gas exchange M; supply of heat released during combustion Qx and heat exchange with walls of intracylinder space Qw. The authors analyzed the influence of each of these factors on the change of pressure in a piston engine cylinder. Defining contribution of each of these factors on the pressure change of the working body in the cylinder will purposefully improve processes in a piston engine, providing not only environmental but also efficiency performance. Although the mathematical model is presented in quasi-stationary formulation, it provides the desired results in design studies, especially in fine-tuning engine to the required performance. When calculating the cycle the most important is accuracy of determination of the start of visible combustion (the beginning of heat supply to the working body by the crank angle φf), as well as determination of mixture ignition time delay (MID) τi. Position of the point by crankshaft angle φf relative to the TDC significantly affects indicator performance and cycle efficiency. Angle φf is an adjustment parameter, so its accepted value is included in the original data for calculation of the cycle. The complexity of considering of influence of various factors on the duration of mixture ignition delay led to a wide variety of empirical or semi-empirical formulas for calculation of MID τi, which significantly complicates their selection for a particular model. The analysis made for the structure, conditions and methods for the preparation of formulas for determination of τi (analyzed 19 semi-empirical and experimental formulas of various authors). The heat involved in the heat exchange between the working body and the walls of intracylinder space is calculated by the formula of Newton-Richman. Increments of pressure and temperature in the pipes are calculated in the exhaust and intake pipes. The described model of piston engine cycle was implemented in a package of piston engines and calculation softwares used in scientific research and educational process.
Izvestiya MGTU MAMI. 2016;10(2):77-83
77-83
Increase of efficiency of alternative fuels use in transport
Abstract
The paper analyzes the results of scientific and research works carried out at the department “Automotive engines” of Moscow State University of Mechanical Engineering (MAMI) in the field of alternative energy, which is widely regarded as the most promising direction in addressing energy and environmental security of the transport complex. The paper analyzes the causes hindering the massive use of alternative fuels in energy consumption of domestic transport, which mostly have lower energy and kinetic performance during combustion compared to conventional fuels. A new approach is stated to solve the problem of increasing chemmotological indicators of alternative fuels on the basis of their preliminary thermochemical conversion - conversion on board of vehicle. Preliminary results show analytical study of the on-board conversion process parameters for a number of potentially suitable alternative fuels with the purpose of process effeciency evaluation. The possibility of practical implementation of the proposed process of chemmotological conversion of alternative fuels with the evaluation of its efficiency was verified by the results of full-scale experimental testing of a diesel engine. The study substantiates the feasibility of using of this process in transport technology due to technical simplicity of its implementation and effectiveness. Implementation of on-board alternative fuel conversion is realizable on any type of serial engine without changing the basic design. The main component of the conversion system, the thermocatalytic reactor, is a simple design heat exchanger, which mass and dimensional characteristics (in the volume of a conventional muffler) provide ease of installation into engine exhaust system. Application of gaseous conversion products improves mixing process because both combustible mixture components, air and fuel, are in the same aggregate state. In addition, the component composition of these products contains reaction active compounds that contribute to improvement of environmental and energy-saving performance of combustion process and efficiency of engine operating cycle.
Izvestiya MGTU MAMI. 2016;10(2):84-92
84-92
Theoretical study of the static characteristics of automotive friction clutch as the automatic control facility
Abstract
Reduction of costs related to automobile operation due to increase of their systems resource is the actual scientific and technical task that can be done in various ways. One of the ways is to use automatics which provide optimal operating modes. It is known that clutch friction pairs of self-propelled machines are less durable components of transmissions therefore above mentioned ideas are especially relevant for them. The disk friction clutch is a system whose state changes during operation due to wear disk pads. Considering it as one of the objects of automatic control of stepped mechanical transmission, it should be mentioned that the change in its state entails a change in the characteristics of work processes flow. If there is no means to address this change or to track and compensate it in automatic control system the algorithm used by system will gradually lose the adequacy to object, which will result the accelerated wear of pads and increase of costs related with both disc replacement and downtime of automobiles during repairs. The presence of clutch elements that have non-linear elastic characteristics in the design allows to assume that this process will have a non-trivial nature requiring to study regularities that in the future will assess their impact on the loading of friction pairs. In this paper, the construction and implementation of appropriate mathematical model solves first of these tasks in relation to the friction of single-disc dry clutch, where pressure is created by the split diaphragm spring with a direct installation.
Izvestiya MGTU MAMI. 2016;10(2):92-102
92-102