Vol 16, No 2 (2022)

BACKGROUND: The paper presents the results of thermometry of pistons with the TsNIDI type combustion chamber (CC) of the D-240 and the D-245 tractor diesel engines. Various constructive and technological measures aimed at increasing the thermal resistance of pistons are considered.

AIMS: To evaluate the effect of heat-protective coatings on the temperature state of pistons with the TsNIDI type combustion chamber.

METHODS: Motor bench tests of the D-240 and the D-245 diesel engines, equipped with pistons with heat-protective coatings (HPC) on the bottom, were carried out. In the process of research, the influence of the HPC on the thermal state of the pistons as well as on the power and economic indicators of these diesel engines was studied.

RESULTS: It is established that hard anodizing leads to a slight decrease in temperatures and their differences at characteristic points of the piston in stationary and non-stationary diesel operation modes. It is noted that the slow rise in temperature at the bottom of the piston is caused by a decrease in the amount of heat supplied to it due to the low thermal conductivity of the oxide layer. It is shown that the PN85Yu15 gas-plasma coating leads to a significant decrease in temperatures and their differences along the piston bottom. It is determined that this coating helps to reduce the specific effective fuel consumption due to the reduction of the ignition delay period in the combustion process. It is noted that a slower growth rate of temperatures and their differences, especially in the zone of the edge of the CC, should reduce the magnitude of thermal stresses, and therefore increase the thermal resistance of the experimental pistons.

CONCLUSIONS: It is revealed that the most effective way to reduce the heat stress of the piston is the application of heat-protective coatings on its bottom. The influence of the abovementioned coatings on the nature of the temperature distribution and their differences in the piston head is investigated.

BACKGROUND: The areas of hydrogen energetics development are analyzed. The main problems faced by Western automakers and which determine the ways to solve the problems of hydrogen vehicles are outlined. It is noted that small-scale production of hydrogen cars has already begun in Europe and the USA. The development of this direction requires the creation of a network of filling stations, which is related to the high financial cost of hydrogen fuel production technologies and the development of the appropriate infrastructure. The world economy transition to a new energy source requires the introduction of large electrical capacities.

AIMS: Technologies of vehicle onboard hydrogen production with use of hydrogen-containing substances are of interest of the study, as they are highly safe, cheap in production and easy in service.

METHODS: The experimental design developments on converting diesel and gasoline internal combustion engines to run on hydrogen, made by NAMI in the past years, are considered. In the development of this direction, MADI has developed an original method for vehicle onboard hydrogen production with hydrogen supply to the cylinders of a bifuel diesel internal combustion engine.

RESULTS: During the tests, an increase in power indicators, an increase in the effective efficiency of the internal combustion engine and a decrease in the content of CH and CO in the exhaust gases of a diesel engine with a certain increase in nitrogen oxides were obtained.

BACKGROUND: The information about application of hydraulic springs in suspension systems of tanks and self-propelled artillery weapons may be found in domestic scientific and nonfiction literature. In addition, machines, which prototypes were equipped with this type of suspension, are known. For instance, possibility of hydraulic suspension implementation was proven on the T-34 tank prorotype, whereas application of this type of suspension with heavy tanks gave the most prospectivity. Complication of sealing build-up with sufficient life span, development of technologies of metal springs strengthening and shutdown of heavy tanks development did not allowed hydraulic suspensions to become widespread. At present, they are not used at all, whereas methods of analytical calculation are not in public access, despite of the interest of a group of scientists.

AIMS: Development of the method of determination of main parameters of suspensions with hydraulic springs and analysis of properties of the T-34-76 Soviet middle tank prototype hydraulic suspension from the point of modern theory of nonlinear suspension systems.

METHODS: Justification and confidence of given dependencies for properties calculation, conclusions and recommendations are confirmed with application of strict mathematical apparatus of mechanics, hydraulics and thermodynamics as well as scientifically justified theoretical backgrounds.

RESULTS: Historic data on liquids compressibility researches, method of analytical determination of main properties of hydraulic springs with various design schemes, allowing restoring of properties of suspensions of existing tracked vehicles, synthesizing properties of other suspensions and, moreover, estimating reasonability of properties of suspension with hydraulic springs, are presented in the article. According to the method, proposed in the article, properties of the hydraulic spring from the T-34-76 Soviet middle tank prototype, equipped with hydraulic suspension, were restored and analyzed. In addition, suspension properties for the same vehicle were synthesized and used for a comparative analysis.

CONCLUSIONS: The information, presented in the article, is helpful for research engineers, interested in study of elastic behavior of liquids in case of their application in suspension systems, whereas the proposed method, allowing synthesis of reasonable properties of hydraulic springs, gives an opportunity to study the ride comfort of tank propotypes, equipped with hydraulic suspension, with a good quality and, moreover, to synthesize hydraulic springs properties according to the demands, given to a design engineer.

BACKGROUND: The antispin regulation (ASR) operation, combined with an individual electric traction drive (IETD) of a city electrobus, may contribute to road safety improvement as well as to economy of electric energy, consumed by IETD from drive battery as a result of decreasing of drving wheels spin.

AIMS: Development of a new operation algorithm of the electrodynamic ASR of the rear axle driven electrobus, based on additional modulation of the vectoral PWM signal, applied to three-phase windings of a stator of a synchronous traction motor and helping to ensure electroenergy economy as a result of consumption decrease and partial energy return during driving wheels regenerative braking,as well as improvement of driving stability on slippery roads.

METHODS: The chosen criterion of operating capability of the ASR operation algorithm is absence of negative impact on road safety, which may consist in loss of course and trajectory driving stability and loss of mobility. Electrobus motion path was used as an integrational measuring tool for quality assessment of these performance characteristics. The chosen criteria of energy efficiency are the summarized averaged electric power, consumed by traction motors, and the summarized averaged electrical power of regeneration, returned by traction motors to the battery throughout the electrobus testing ride.

RESULTS: With simulation methods, it was found that the summarized averaged power of the electrobus, featured with the ASR, driving on slippery road, is 9.7% less than the power of the electrobus without the ASR in the same conditions.

CONCLUSIONS: The summarized economy, resulted from decreasing of energy consumption (driving wheels spin is eliminated) and partial energy return back to a battery during driving wheels regenerative braking, may be up to 26.8% of the summarized averaged electric power, consumed by traction motors of the electrobus with the ASR.

BACKGROUND: Diesel engines, used in generator units, primarily operate in variable loading conditions. Therefore, their technical and economic performance generally deteriorate when the load decreases. It arises from the diesel engine fuel system feature, where pressure and quantity of the fuel, injected into a cylinder, reduces with the load decreasing. As a result, the injection becomes “sluggish”, the quality of mixing process and combustion becomes worse.

AIMS: Improvement of effective indicators of the diesel-generator units with electronically controlled fuel injection.

METHODS: Adjustment of operation modes of the diesel engine of the electrical power unit carried out with use of electronically controlled Denso solenoid, connected to the high-pressure fuel pump via an adapter.

RESULTS: Results of the motor testing of the low power diesel-generator unit with electronically controlled fuel feed system are described in the article. The oscillograph charts of valve displacement and solenoid magnet winding current, presented in the article, confirm its operation efficiency. Sharp decrease in boost current at the stage of valve lift can be explained by onset of back EMF. Stable solenoid operation at diesel operation velocity of 3000–3100 min^-1 is achieved by means of boost impulse supply to its winding. The boost impulse is supplied from a voltage upconverter and generated by discharge of preliminary charged booster capacitor.

CONCLUSIONS: Separated fuel feed adjustment in each high-pressure pump section made possible to reduce intersectional fuel feed irregularity to zero. Significant fuel consumption reduction was revealed with the motor testing of the low power diesel-generator unit with electronically controlled fuel feed system (the reduction reaches 10% on low loading operation modes). As mentioned by authors, transition to electronic control of operation modes of diesel engines of autonomous electrical power units does not require major engine design change – only to dismantle a mechanical controller and to set an adapter with electronically controlled bypass valve at a section of the high-pressure fuel pump. Electronic control unit supplies current to the valve. For autonomous electrical power units, transition to this control method can be done in typical repair workshop conditions, and an update of one unit (e.g. the KIPOR KDE19AE3) costs 13 950 rubles. By doing so, one electrical power unit may save up to 1191 liters of fuel and more than 63.96 thousands rubles at a cost of 53.7 rubles per liter.

BACKGROUND: Ensuring transport accessibility of arctic zones of the RF, according to the strategy of social and economic development of the Russian Federation until 2030, is an important and relevant objective.

AIMS: The article contains the results of the study of motion of the 6WD snow and swamp-going vehicle with traction electric drive, developed at the “Wheeled vehicles” department of Bauman MSTU as part of development of snow-going vehicles line-up for the sake of improvement of transport accessibility for people living in arctic zone of the RF.

METHODS: On the basis of the RM 650-2 6X4 all-terrain vehicle, the state-of-the-art electric snow- and swamp-going vehicle with a light-weight welded frame, an electric power unit, a lithium battery as a power-supply source and electromechanical transmission was designed. The vehicle equipped with systems of control, cooling and lighting as well as sensors and measuring complexes. Studies were carried out with various vehicle operation modes (on direct gear with current limit, without current limit and on low gear). Soil road and prepared cross-country terrain were used as a profiled track.

RESULTS: The time-domain diagrams of traction electric drive operation and the vehicle dynamic characteristics were obtained as the study results.

CONCLUSIONS: The obtained values and characteristics point at high level of vehicle power equipment and at prospects of designs, used in the snow-and swamp-going vehicle. The study results can be used for modernization of existing vehicles and for development of high-technology machinery, based on electric power unit.