Course work on the subject of energy installations of transport equipment

Contents

Introduction

In today's world, transport plays a crucial role, allowing people and things to move not only within one country, but also in cross-border directions. Therefore, occupations related to transport will always be popular. After all, it is thanks to them that cargo and passengers are quickly delivered to different, even the most remote and inaccessible places on our planet.

The basis of road energy in the near future will remain piston internal combustion engines (PDVS) due to their high economy, low metal consumption, reliability and relative durability. The piston internal combustion engine is today the most common thermal engine. It is used for the drive of means of the land, air and water transport, the military, agricultural and construction equipment, electric generators, compressors, water pumps, pomp, the motorized tool and other cars, both mobile, and stationary, and is made in the world annually in number of several tens of millions products. In addition, the design and workflow will also be subject to regulatory limitations and process requirements.

It is also natural that the trend in the development of PDPA will manifest itself in the desire to obtain the maximum effective efficiency by using more complex solutions and technologies in it. Assuming a shortage of labor, there will be a trend towards the development and technology of engines that require minimal maintenance and repair costs.

If you turn to fuel, here it can be noted that in the world there is a tendency to produce products according to technical requirements close to the limit. This is due to the desire to produce more fuel to meet the growing need for it. A decrease in fuel quality will force us to look for solutions that would avoid possible negative consequences in operation.

Deep understanding of the principles of the PDVA, strict scientific validity of ways and methods of further improving PDVA are the main requirements for a specialist of the future.

The main problems in the design of PDVS:

improved fuel economy;

improving the environmental characteristics of PDMA;

higher reliability.

increased mechanical efficiency

reduce the area of rubbing surfaces

In this regard, the main task of the specialist of the future is: the development of environmentally friendly automobile power plants that ensure high quality and efficiency of road transportation with minimum labor costs, operational materials and energy during their production and operation.

The following requirements for the power plant can be formulated: transport efficiency, safety of transport services, ensuring transport comfort and safety of goods during transportation, harmless impact on the environment, conservation of natural (fuel and energy, material, labor) resources.

Specialty 05B71300 "Transport, Transport Technology and Technologies" refers to the fields of science and technology, which include a set of means, methods and methods of human activity aimed at the development, implementation, production, installation and operation of transport technology, as well as research in the field of lifting, construction, road and automotive engineering.

1 Heat calculation and heat balance of the engine

Calculate four-stroke diesel engine with turbocharged pk = 0.170 MPa. Effective rated power Ne, = 180 kW at crankshaft speed = 2100, min1, number i = 6 and V-shaped arrangement of cylinders, undivided combustion chamber and film mixing. Cooling system: liquid. Compression ratio a = 16.5.

1.1.3 Temperature of heating of a fresh charge ΔТ (J)

During the filling process, the temperature of the fresh charge increases slightly due to heating from heated engine parts.

In thermal calculation of engine ΔT is accepted on the basis of available experimental data and indirect calculations (Table 1).

We accept the heating temperature of the fresh charge ΔT = (-5)... (+ 10) = + 5 ° C.

1.6 Indicators of engine operating cycle

The indicator indicators of the working cycle characterize the perfection of the working cycle in terms of thermal use, the quality of organization and the course of processes. These include mean indicator pressure pi, indicator pressure p.p.d. ¼ i and specific indicator fuel consumption gi .

Strength calculation of engine parts

In the course design, the strength calculation is made only for the main parts in accordance with the assignment for the course design. Before you begin to calculate parts for strength, you must select or install the material and heat treatment of this part; find out what forces and in which sections create dangerous stresses; Determine whether all forces are defined in the dynamic calculation or whether further calculations are necessary to determine them. The calculation of each part shall be accompanied by a sketch indicating the hazardous sections and dimensions required for the calculation. In addition, allowable stresses and strength reserves shall be specified in the strength calculations to assess the strength characteristics of the designed part or assembly.

5.1 Prerequisites for calculation and calculation modes

Calculation of parts in order to determine stresses and deformations arising during engine operation is carried out according to the formulas of resistance of materials and machine parts. To date, most of the calculated expressions used give only approximate stress values.

The discrepancy between the estimated and actual data is due to various reasons, the main of which are:

Absence of a valid pattern of stress distribution in the material of the calculated part; use of approximate design schemes of forces action and place of their application; the presence of difficult-to-consider alternating loads and the impossibility of determining their actual values; difficulty in determining the condition of operation of many engine parts and their thermal stresses; influence of non-accurately calculated elastic vibrations; Inability to accurately determine the effect of surface condition, machining quality (mechanical and thermal), part dimensions, etc., on the amount of stress encountered.

In this regard, the calculation methods used make it possible to obtain stresses and strains that are only conditional values ​ ​ and characterize only the comparative strength of the calculated part.

The main loads acting on the engine parts are pressure forces of gases in the cylinder and inertia of translationally and rotationally moving masses, as well as forces from elastic vibrations and thermal loads.

The gas pressure load varies continuously during the operating cycle and has a maximum value only in a relatively small portion of the piston stroke. The load from inertial forces has a periodic nature of change and in high-speed engines sometimes reaches values ​ ​ exceeding the load from the pressure of gases. These loads are sources of various elastic vibrations, which pose a danger in resonance phenomena.

Forces from temperature loads resulting from heat generation during combustion of working mixture and friction reduce mechanical strength of materials and cause additional stresses in conjugated parts with their different heating and different linear (or volumetric) expansion.

Conclusion

As a result of the course design, the piston internal combustion engine was calculated, the effective rated power of which is Ne = 180 kW at the crankshaft speed = 2100 min1, the number i = 6 and the V-shaped arrangement of the cylinders.

The design part consists of five parts: thermal calculation and thermal balance of the engine, calculation and construction of the external speed characteristic of the engine, kinematics of the crank gear mechanism, dynamics of the crank gear mechanism and strength calculation of engine parts.

The following processes are considered in the thermal calculation and thermal balance of the engine: the intake process, the compression process, the combustion process, the expansion process, the exhaust process. Engine thermal balance working cycle indicator diagram was calculated.

In the second part, the external speed characteristic of the engine was calculated.

In the kinematics of the crank mechanism, the following are calculated: piston movement, piston speed and piston acceleration.

The calculation of the dynamics of the crank mechanism consisted in the scanning of the indicator diagram, calculations of the inertia forces of the moving masses of the KSM, the total forces and moments acting in the KSM and in the construction of a polar diagram of the pressures on the connecting rod neck.

The following calculations were made in the strength calculation of engine parts: calculation of parts taking into account variable load, calculation modes, calculation of parts of the piston group, calculation of the piston ring, calculation of the piston pin, calculation of parts of the connecting rod group.

On the basis of the calculation part, a graphic part is made, in which it is displayed on sheets in formats A1:

- indicator diagram; movement chart; speed diagram; acceleration diagram; design diagram of KSM; external speed characteristic; drilldown of the indicator chart; a diagram of normal and longitudinal forces; radial force diagram; tangential force diagram; crankpin pressure diagram and four-stroke engine torque diagram.

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