Methods for controlling the elastic damping characteristics of pneumatic seat suspensions

The pneumatic seat suspension is one of the most important, and in some situations, one of the key components of the vibration protection system for the human operator of the vehicle. At the present stage of scientific and technical activities of most developers, great emphasis is placed on controlled seat suspension systems, as the most promising systems. This article analyzes the methods of controlling the elastic damping characteristics of the air suspension of a vehicle seat. Ten dif-ferent and fairly well-known methods of changing the shape and parameters of elastic damping characteristics due to electro-pneumatic valves, throttles, motors, additional cavities, auxiliary mechanisms and other actuators were considered, the advantages, application limits and disad-vantages of each method were analyzed. Based on the results of the performed analytical procedure, as well as the recommendations known in the scientific and technical literature on improving the vibration-protective properties of suspension systems, the authors proposed and developed a new method for controlling the elastic-damping characteristic, which is implemented in the proposed technical solution for the air suspension of a vehicle seat. The method differs in the thing that it im-plements a cyclic controlled exchange of the working fluid between the cavities of the pneumatic elastic element and the additional volume of the receiver on the compression and rebound strokes, forming an almost symmetric elastic damping characteristic, and partial recuperation of vibrational energy by a pneumatic drive, presented in the form of a rotary type pneumatic motor. In addition, the method does not require an unregulated hydraulic shock absorber, while still having the ad-vantage of improved vibration-proof properties of the air suspension of a vehicle seat over a wide range of operating influences.

Applied science and manufacturing: NAMI and VTZ

Starting from the 1960s, a number of acute problems appeared in the engine building during the transition to diesel engines of a new generation, the engines with direct fuel injection into the chamber in the piston. The short time allotted in the cycle for mixture formation and combustion, especially for high-speed diesel engines, makes it extremely scrupulous to approach this in order to obtain high and stable technical and economic indicators. One of the many problems is the organi-zation of efficient and uniform gas exchange across the samples to reduce the spread of final indica-tors during mass production. The article deals with this very problem, specifically - in the case of chill casting of individual heads at the Vladimir Tractor Plant (VTZ) using composite rods of inlet and outlet channels. The method of static blowing of inlet channels developed at Central research and development automobile and engine institute NAMI with a quantitative assessment of the re-sistance and vortex formation in the cylinder was applied. The gas-dynamic parameters (GP) were checked for the heads that received individual numbers in a statistically significant sample of billets on one test bench several times, sequentially according to the stages of the processing. It is shown schematically how these parameters changed during processing and assembly of the heads. It is im-portant that a high “hereditary” correlation is obtained between the GP of the billets and fully ma-chined and assembled cylinder heads. The manufacturing cost of the latter is incommensurably higher than the castings cost. Therefore, according to the results of the work, in order to reduce the cost of products and increase the level and stability of quality, an important decision was made on the early flaw detection of the GP (after casting) with the subsequent remelting of those blanks that are most likely “genetically, hereditarily” will not provide the declared technical and economic in-dicators in assembled product. Similar approaches can be used in the organization of production and other goods with high added value of technological operations required after procurement to ensure the quality of final products.

Physicochemical characteristics of solid particles of contaminants in the coolant of automobile and tractor engines

The article describes the results of a study of the physicochemical characteristics of solid particles of contaminants present in the coolant of automobile and tractor engines. The data on the fractional, physical and chemical composition of solid particles of contamination are given. It was established that the generalized reason for the appearance of contaminants of various nature in liquid cooling systems of engines is the physicochemical interaction of the coolant (antifreeze) with different elements and dissimilar materials of the cooling system. The use of absolutely pure coolant in the cooling systems of automobile and tractor engines is practically unrealistic, since there will always be operating conditions that contribute to the formation of contamination. A number of chemical elements (in an amount from 1 to 47% of each element) were found in the composition of solid particles of coolant contaminants: iron Fe, silicon Si, aluminum Al, lead Pb, tin Sn, zinc Zn, calcium Ca, magnesium Mg, copper Cu. In addition, at a level of less than 1.0% (wt.), Such chemical elements as potassium K, sodium Na, titanium Ti, phosphorus P, sulfur S, chromium Cr, molyb-denum Mo, chlorine Cl, iridium Ir, nickel Ni, manganese Mn, etc. were found. The most dangerous contaminants are particles of iron Fe and silicon Si, contained in the coolant in an amount of up to 47 and 37%, respectively, and possessing significant hardness and angularity. The abrasive proper-ties of Fe and Si particles create the danger of removing a thin oxide film on the inner surface of the walls of the cooling radiator channels, leading to their premature destruction. In this regard, it is concluded that high-performance engine coolant filters should be used in automobiles and tractors to remove these contaminants from the flow.

Compressor type engine brake

The accident rate in road transport remains unacceptably high, and in order to reduce it, it is nec-essary to take into account all the factors affecting this process. In this regard, the process of long-term braking deserves special attention, which negative processes require the creation of additional braking systems (retarder brakes) for vehicles operating in mountainous areas, primarily in the field of passenger transportation. Transmission retarder brakes that provide sufficient braking performance have a number of dis-advantages that inhibit their use. Existing engine retarder brakes provide insufficient deceleration, and studies were carried out at the Kuban State Agrarian University (KubSAU) to improve their efficiency. After a theoretical analysis, the compressor brake mode was experimentally investigated. The in-creased pressure was created in the intake manifold and at the end of the compression stroke, air from the cylinder was released through a special valve back into the system, due to which the brak-ing effect was created. The carried out experiments confirmed the possibility of a significant increase in the engine braking torque in the compressor brake mode, when both valves are closed - the exhaust after the exhaust manifold and the intake in front of the carburetor, and compressed air is supplied to the in-take manifold at different pressures. Then the braking torque increases in comparison with engine braking by more than 3 times.

V-belt transmissions of agricultural machines

The article is devoted to the analysis of design features and operating conditions of V-belt trans-missions of agricultural machinery. When designing these gears, it is recommended to give prefer-ence to gears made according to an open circuit or with a tension roller located outside the belt con-tour, to avoid cross and semi-cross gears, as well as multi-pulley gears with crossing shaft axles. To make the wider use of more progressive types of belts. It was shown that the features of V-belt transmissions of agricultural machinery require clarification of the methods for calculating trans-missions with progressive types of V-belts and automatic belt tensioning methods. It was noted that special attention should be paid to transmissions with multi-profile belts, which calculation has not been sufficiently reflected in domestic regulatory documents. The advantages of such belts are es-pecially noticeable under variable and shock loading. Based on the analysis, the recommendations for clarifying the calculation of belt drives with multi-profile belts were given. Analytical dependencies are proposed for determining the value of the nominal power transmitted by one belt (stream) of a multi-profile belt, allowing automation of the calculation of V-belt transmissions of agricultural machinery. For gears with a tension or guide roller that add an extra (sometimes reverse) bend of the belt, it is proposed to determine the coeffi-cient taking into account different degrees of bending on the pulleys according to a graph built tak-ing into account the linear hypothesis of summation of damages. It is recommended to calculate gears with spring-loaded tensioning rollers and design tensioning devices for such transmissions using a special method that takes into account the belt tensioning method. At the same time, the required value of the pre-tension of the belt can be significantly re-duced, which will have a positive effect on its resource, without losing the traction capacity of the transmission itself. Expressions are given for finding the value of the pre-tension of belts, both for gears with tension due to the elasticity of the belt, and for gears with spring-loaded tension rollers. Conclusions and directions for further research are formulated.

The development of tractor theory

The article discusses the main developments of the author in the field of tractor theory, which were published at different times and in different editions of technical literature, including Tractors and Agricultural Machinery journal. These are traction dynamics of the tractor; modular energy technology facilities and block-modular tractor aggregation system; a method for optimizing the type of a tractor, as well as the combustion chamber of the D-75 engine implemented in production and GOST for testing agricultural tractors.

Development of the design of an internal combustion engine cooling system with a pre-starting heating function

The main topic of the article is the development of an effective design for a pre-starting heating system for an internal combustion engine for conditions of limited power supply. The work to im-prove the design of light wheeled all-terrain vehicles on low pressure pneumatics is done at Pacific National University. Prototypes of light wheeled off-road vehicles are used mainly in agriculture and for forestry production. There are prerequisites for their use in oil and gas fields in the Far North conditions. This vehicle is operated all year round, in the absence of power supply, it is stored in the open air, so the problem of starting a cold engine is quite important, and the topic of creating a design for a pre-starting heating system for an internal combustion engine under conditions of limited or com-plete absence of power supply is relevant. The purpose of the work is to develop and study the efficiency of the pre-starting heating system for an internal combustion engine with liquid cooling for conditions of limited power supply. Our own design of the cooling system with a pre-starting heating function based on a gasoline burner was developed. To assess the efficiency of the engine warm-up process, the circuit was as-sembled on a light wheeled all-terrain vehicle. The experimental studies were carried out to deter-mine the regularity of changes in the temperature of the engine coolant during pre-starting heating at different ambient temperatures. The results of the experiment indicate the high efficiency of the developed system based on a gasoline burner. The average heating rate of the engine coolant during the warm-up process was 2.1 - 2.8 оС per minute, which indicates an intensive pace of pre-starting heating.

Determination of the optimal composition of mixed fuel based on the environmental performance of a diesel engine

The use of rapeseed oil (RO) in tractor engines and other agricultural machinery in its pure form or a mixture of RO with diesel fuel (DF) imposes a number of limitations associated with some dif-ference in physical and chemical properties. Therefore, the most promising is the use of mixed fuel (MF) consisting of DF and RO. The purpose of these studies is to determine the optimal composi-tion of the MF, consisting of DF and RM by optimizing the approximated dependences of the envi-ronmental indicators of a diesel engine. To solve this problem, bench tests of the operation of the D-245.5S diesel engine (4ChN 11.0 / 12.5) were carried out. The following determined environmental performance indicators of a diesel engine are selected: soot (С), nitrogen oxides (NOx), unburned hydrocarbons (CxHy), carbon dioxide (CO2) and carbon monoxide (CO). The studies were carried out on various compositions of MF, consisting of 80% DF and 20% RO, 55% DF and 45% RO, 20% DF and 80% RO by weight, respectively. As a result of the bench tests, two load characteris-tics were obtained, the one at a speed of n = 1400 min-1 corresponding to the value of the maximum torque, and the second at a speed of n = 1800 min-1 corresponding to the value of the rated power, as well as the external speed characteristic of the D-245.5S tractor diesel engine (4ChN 11.0 / 12.5). The analysis of the obtained experimental data revealed the dependence of environmental indicators on the rotational speed of the diesel engine crankshaft, the average effective pressure and the addi-tion of RO in MF by weight. Using the least squares method, the approximated mathematical de-pendences of the ecological indicators of a diesel engine are determined. The analysis of the ob-tained dependencies showed that: the increase in the crankshaft speed n, the proportion of RO in MF and a decrease in the average effective pressure pe, leads to a decrease in soot С to 4.0%, nitro-gen oxides NOx to 100.0 ppm, unburned hydrocarbons CxHy to 1.0 ppm, carbon dioxide, CO2 up to 2%, and an increase in carbon monoxide CO up to 0.16%. As a result of solving the obtained system of equations for the approximated dependences of environmental indicators, the optimal addition of RO to MF of up to 35% by weight was determined.

Evaluation of methods for experimental and analytical determination of the contour area of the contact patch of a pneumatic tire with a support base

Subject of study. The results of experiments on the estimation of the error of methods of experi-mental and calculated determination of the contour area for the ecological assessment of a mobile energy device (MED) are presented. There was used the example of modern radial tires 360 / 70R24 of Bel-89 and 18.4R34 of F-11 agricultural tractor MTZ-1025.2. in modes of non-nominal loading at nominal load on tires and changes in tire pressure within the range recommended for field work. The purpose of the study. To assess the possibility of improving the computational method for determining the contour area of the contact patch of the tire tread of a pneumatic wheel based on the mathematical model of V.L. Biederman. Materials and methods. The assessment was carried out for four ways of determining the area of the tire contact patch: 1) directly measuring the area using a digital photograph of the tire contact patch in Kompas-3D V13 software with the de-termination of the scaling and method error using a square from 100x100 mm graph paper; 2) calcu-lation by the formula of the area of an ellipse, using the length and width of the tire contact patch, measured with a tape measure directly from the obtained print; 3) by calculation, determined from the digital photograph in Kompas-3D V13 software; 4) by calculation, determined by calculation using the parameters of the universal tire characteristic (UTC). Results and discussion. As a result of the experiments, it was found that for modern radial tractor tires, the static deformation of which does not exceed 18-22%, the method of theoretical determination of the contour area of the tire contact patch using the UTC parameters can be applied with sufficient (for engineering practice) accuracy. Full convergence of the calculated and experimental contour areas of the tire contact patch can be provided by the coefficient of their ratio. Conclusions. The carried out assessment of the possibility of using methods for calculating the conditional contour area of the tire showed that these methods can be well used for a comparative assessment of the technogenic mechanical impact of propellers on the soil.

Energy intensity of chopping fructified raspberry stems

The article analyzes the results of measuring the force required for the destruction of a dried raspberry stem by means of transverse action on it. There was used as a variant of the experiment the cutting of stem with support at one and two points, as well as breaking it with a distance between the supports of 30 and 54 mm. It was found that the force on the working body linearly depends on the diameter of the stem. The essential dependence of the required force on the method of action on the material was confirmed. It was revealed that the effort to cut a dried stem is significantly higher than the effort required to break it. To implement the breaking process, a working body in the form of a pair of horizontal twelve-blade rotors mounted with a radial overlap between them by an amount approximately equal to the distance between the outer edges of the adjacent blades is proposed. In this case, the rotors should have a diameter of about 200-210 mm. In addition, they must be equipped with a synchronous drive and shifted in phase by an angle of 150. As a result of modeling the phases of the destruction of the stem by transverse fracture, the force and energy parameters of the process were obtained. With a rotor length of one meter and simultaneous crushing of 25 stems, the average power required to drive is 9.3 kW, with a probability of peak val-ues of 16.4 kW. When calculating the strength, it should be taken into account that a distributed load of up to 12,400 N acts on the rotor shaft in the vertical plane and a distributed load of 2,750 N acts in the horizontal plane. A prototype grinder was tested and proven to work.