Vol 88, No 5 (2021)

The subject of the research is to determine the parameters of the diesel intake and gas exchange pro-cess when using a mixed fuel (MF), consisting of diesel fuel (DF) and rapeseed oil (RO). The main goal of this work is to determine the dependences of the parameters of the intake and gas exchange of a diesel engine on the composition used by the MF. To achieve this goal, theoretical and experimental studies of the D-245,5S tractor diesel engine with a characteristic of 4ChN 11,0/12,5 were carried out on the following MF compositions: DF – 80 % + RO – 20 %, DF – 45 % + RO – 55 %, DF – 20 % + RO – 80 %, as well as pure diesel fuel. During the carried out studies there were obtained the dependences of the hourly air flow rate, the cylinder filling factor and the charge density in the intake manifold of a diesel engine when operating on DF and MF on the crankshaft rotation speed and load at = 1800 min–1 and = 1400 min–1. It is theoretically determined and experimentally confirmed that the composition of the used MF has practically no effect on the characteristics G_в, η_v and ρ_к depending on p_e of the diesel engine. As a result, it was found that with an increase of n from 1400 to 1800 min–1 on all compositions of MF the G_в increased from 276 to 394 kg/h, from 1,44 to 1,70 kg/m3, and at increase of n from 1800 to 2000 min–1, the G_в decreased from 394 to 322 kg/h, from 1,70 to 1,49 kg/m3 and from 0,97 to 0,77. With an increase p_e from 0,2 to 1,2 MPa on all compositions the MF increased, at n = 1400 min–1, from 187 to 276 kg/h, ρ_к from 1,29 to 1,44 kg/m3 and η_v from 0,73 to 0,97, at n = 1800 min–1, G_в from 274 to 394 kg/h, ρ_к from 1,29 to 1,69 kg/m3 и η_v from 0,83 to 0,91, respectively.

The issue of rehabilitation of abandoned agricultural lands in Georgia is currently topical. In the rehabilitated areas there are grapes, intensive orchards and various plantation crops planted. Rehabilitation includes clearing the soil from plants and root systems, deep tillage, setting up a ridge and preparing the soil for planting seedlings. It is known that out of agricultural work the cultural and technical work is characterized by the highest energy and labor costs. One of such energy-intensive operations in land rehabilitation technology is cleaning the soil from the root system of plants. Despite technical progress, a number of problematic issues in the design and manufacture of machinery for some agricultural work have not yet been resolved. The fact is that in soil rehabilitation there are used the machines, which working bodies do not take into account in their design the rheological parameters of the treated medium. As a result, there is non-technological work with high energy consumption and mechanical erosion of the pro-cessed medium. Often there are expensive, wide-cut mulchers of European production with hammer-shaped working bodies. Its use contradicts the theory of cutting and crushing the soil and gives especially negative results when processing soil with high humidity.

The paper presents a technology and a system of machinery for the rehabilitation of abandoned agricultural areas. The basic principles of designing existing machinery for land rehabilitation are considered. The prerequisites for the design of the working bodies of rotary agricultural machines operating in an elastic-plastic medium are presented. It is noted that the basis for the creation of tillage machines should be the rheological and mechanical parameters of the treated medium. Using the theory of impact, the process of interaction between cutting knives and the root system of a plant in a soil environment was investigated. An analytical image for calculating the impact force was obtained.

To determine the indicators of the mobility properties of unmanned tracked trains and the formation of traffic control laws, it is advisable to use mathematical simulation. On the example of a tracked semitrailer train, a mathematical model is being developed. It consists of a large number of rigid bodies connected by kinematic and power connections; therefore, it is proposed to use software systems that make it possible to synthesize a system of equations for the dynamics of a tracked train in an automated mode. The article discusses general approaches to the formation of such systems of equations in modern software packages for automated analysis of the dynamics of body systems. There are given a structural diagram of the developed mathematical model of a tracked train and a description of its main structural elements (blocks), which are responsible for the operation of various systems: a power plant, transmission and running system.

The features of the interaction of active sections of a caterpillar propeller with a low-deformable support base of the “dense soil” type are considered. On the example of the maneuver “turn with a given radius”, an imitation mathematical modeling of the movement of a caterpillar train was carried out, and on the basis of an analysis of the results obtained, the operability of the developed mathematical model was confirmed. The developed mathematical model of the movement of a tracked semitrailer train makes it possible to study its movement in space, taking into account the mutual influence of the tractor and the semitrailer, taking into account the interaction of the active sections of the tracked propeller with the sup-port base and taking into account the modeling of the working processes of its systems.

Based on the study, it can be concluded that the use of the method of computer modeling of the dynamics of body systems is an effective tool for predicting the performance indicators of tracked trains, determining the laws of traffic control, and also for assessing energy efficiency when performing virtual maneuvers. The developed mathematical model of the dynamics of a tracked train allows a wide range of studies to assess the mobility of tracked trains of various design and layout.

A method for calculating the traction motor of a hybrid transmission of a front-end loader is proposed. It is indicated that these vehicles are characterized by a mode of operation with multiple accelerations and decelerations, as well as alternating operations with high and low required traction force. An electromechanical transmission scheme is proposed. This scheme can be effectively used in such conditions.

The proposed method uses the concept of the magnitude of the range of an electric motor, which can be used to select a specific electric motor that provides the required mobility of the vehicle. For a front loader with a lifting capacity of 3500 kg, a maximum speed of 40 km / h and a maximum specific thrust of 1, the main parameters of the traction motor were determined. However, for the transmission with one fixed gear ratio (EMT1), an electric motor with an excessively high power was obtained. Therefore, the determination of the characteristics of the electric motor for an electromechanical transmission with two fixed gear ratios (EMT2) was carried out. In the process of calculating this transmission, a significantly lower required engine power was obtained.

The article provides an approximate assessment of the energy efficiency of EMT1 and EMT2 transmissions. A method to determine the efficiency of an electric motor depending on its operating mode (on the current angular speed of the shaft and torque) was used. It was determined that the EMT2 transmission has the best efficiency of the electric motor both during bulldozing operation and when driving at maximum speed.

The general conclusion is that it is most rational to use a transmission with two fixed gear ratios. As a further direction of research, the use of computer simulation for evaluating the energy efficiency of a loader in a loading-unloading cycle is highlighted.

The procedure for the calculation of loading reduction of the bearing assembly of the automotive diesel engines turbocharger forced aspiration by using composite materials for the rotor impellers is decribed. The most significant parameters for such an assessment are the reaction force in the bearing oil layer, the frictional moment in the oil layer, and the relative internal and external clearances in the bearings. The software Flexible Rotor was used as the main computational tool of this study. This software is registered in the register of applied programs for computers No. 2006611094. The study considered the following design options for rotors with a combination of wheels made of different materials: 1) impellers made of traditional metal materials – compressor wheel made of aluminum alloy, turbine wheel made of heat-resistant nickel alloy (basic version); 2) сompressor wheel made of composite, turbine wheel made of heat-resistant nickel alloy; 3) aluminum alloy compressor wheel and composite turbine wheel; 4) a compressor wheel and a turbine wheel made of composites. According to the evaluation studies, the most rational options for variable wheel combinations in the rotor design are proposed. In general, the results of the calculations showed that a decrease in the mass-inertial characteristics of the rotor due to the use of composite materials with a low density leads to a decrease in bearing loads and a reduction in friction losses by up to 3 times. The established reduction of the friction torques reduces the intensity of the dissipation of mechanical energy in the bearings. This has a positive effect on the energy efficiency of the turbocharger and reduces the temperature of oil heating from friction.

Sorghum is one of the staple foods in the Republic of Burundi, where food security is at risk. Sorghum is genetically adapted to hot and dry agroecologies and is used not only as food, but also as feed for poultry and cattle. There is a problem of increasing the yield of sorghum and reducing the high labor costs in its cultivation in the Republic of Burundi, since in general agriculture is characterized by a natural species with a predominance of food and seasonal crops, which occupy about 90 % of the cultivated land. Traditional African agriculture is based on a system with individual elements of intensive farming and is not well prepared for the use of high-tech machinery and tools of production. On the plots of a peasant family of about 0,8 hectares (two acres) with the help of a hoe and a machete with a shift farming system, the yield of sorghum reaches 1,0 ... 1,3 t / ha. For peasant farms in the form of production cooperatives with an area of 200 ... 300 hectares, where it is possible to conduct intensive farming and to use of modern technical units of high productivity in order to increase yields several times, there was proposed the Mounted discochisel harrow developed in the Kuban State Agrarian University. The harrow consists of a three-girder frame, brackets, a disc module, disc rippers, a chisel module, chisel rippers and a packer roller. Its purpose of peeling, plowing and seedbed cultivation, thanks to a special regulating mechanism, is performed by the unit in one pass. This will help to achieve lower operating and energy costs due to the fact that tillage work is carried out in a very short time.