Dynamic calculation of engine 2H. Course

Task

1. Brief description of the engine, selection of initial parameters to obtain an indicator diagram;

2. Construction of engine indicator diagram;

3. Calculation and plotting of change of forces of one cylinder acting on KSM:

- inertia forces;

- gas pressure forces;

- driving forces;

- lateral force;

- radial and tangent force;

is the total tangent force.

4. Analyses the design of a given part that is used in this model - the flywheel.

6. Conclusions

Engine description 2h 10.5/13

Type of engines: four-stroke, vertical, with vortex-chamber mixing two-cylinder, block-block design with block covers for every two cylinders. In two-cylinder engines, tunnel-type block crankcases, crankshafts are installed on rolling bearings.

At the rear end, the shaft has a flange or cone for attaching the flywheel. Gears of gas distribution drive and water pump are secured on front end of shaft.

Diesels connecting rods stamped from carbon steel, rod of I-rod. Bronze bushing is pressed into upper head of connecting rod. The lower head of the connecting rod is detachable, the plane of the connector is located at an angle of 45 ° to the rod of the connecting rod. The cover of the lower head is stamped steel, attached by two bolts screwed into the connecting rod body. Inserts of the lower head of the connecting rod are made of aluminum-nickel alloy.

Piston of two-cylinder engines cast, cast iron;

Six piston rings are installed on the piston, four of which are rectangular compression rings, two are oil-removable. All rings are cast iron, the upper compression ring is chrome. Piston pin of steel, cemented floating type.

Gas distribution

The engine has one steel distribution roller, forged. For both two-cylinder engines, it is forged together with cams of inlet, outlet valves and fuel pumps. The profile of the inlet and outlet cams is the same. Distributing roller is installed on two ball bearings and is driven from crankshaft through gear train. On the distribution roller of the four and six-cylinder engines for driving the fuel pump, a gear is installed. Camshaft of engines is installed in bronze bearings.

Fuel supply system

Engine fuel system consists of filter, high-pressure fuel pump, nozzles and pipelines. No booster pump is installed on two-cylinder engines.

Filters. In the engine fuel system, a felt filter is installed, a slot filter is installed on the nozzle.

T o l and in n i high pressure pump. Individual single-plunger pumps are installed on the two-cylinder engines. The amount of fuel supplied is controlled by changing the supply end by rotating a pump plunger having a spiral cut-off edge on the cylindrical surface. Individual fuel pumps are driven from distribution roller. Drive roller of unit fuel pump with distributing roller of engine is connected by means of gears, and with cam roller of fuel pump by means of elastic coupling.

Closed type nozzle with pin sprayer. Needle opening pressure 140 5 kG/cm2. Nozzle hole diameter is 1.5 mm. Pin cone angle 15 °.

Regulator

Regulators of one of two types are installed on the engine:

1) all-mode centrifugal precision regulator of HLR, direct action with elastically connected cataract and variable degree of non-uniformity. The regulator is installed on engines designed to connect to alternators operating in parallel on a common network;

2) single-mode limit regulator, which allows insignificant adjustment of the number of revolutions.

Lubrication system

Engines lubrication system includes:

1) gear-type oil pump, for one- and two-cylinder engines is installed at the front end of the engine and is driven from the crankshaft through the shank,

2) filter of main cleaning of reticular type;

3) diaphragm type oil cooler,

4) fine filter with cardboard cartridge DASFO1,

5) screen receiving filter in tray. The pump sucks oil from the tray through the intake filter and pumps it through the main filter to the oil line and fine filter. The pressure in the system is 1.5 - 3 kG/cm2.

Cooling system

The engine cooling system may be closed, double-circuit or flow-through depending on the purpose of the engine. At flow cooling system, engines are equipped with one circulating water pump of vortex type, with gear drive from crankshaft installed on attachment cover of units. With closed cooling system, engines are supplied with additional centrifugal pump of sea water, which pumps water through heat exchanger. This pump is installed on the attachment cover of the units and is driven from the roller by a parasitic gear, with which the tail of the roller of the water pump engages. The circulating water pump pumps water into the central main line of the blockcarter, from where water enters the carved space of the cylinders and flows into the cavity of the cylinder cover, and then into the drain pipeline. The four- and six-cylinder engines cool down the exhaust manifold. Thermostat is installed in refrigerator end face.

Start-up system

Start of 2H 10.5/13 engines is performed manually. In addition, the engines are equipped with an electric start-up. Electric starting system includes starter ST25, storage battery 6 STE144 or 6STE128, charging generator GSK1500, voltage relay and filament plugs.

Type of engines: four-stroke, vertical, with vortex-chamber mixing two-cylinder, block-block design with block covers for every two cylinders. In two-cylinder engines, tunnel-type block crankcases, crankshafts are installed on rolling bearings.

At the rear end, the shaft has a flange or cone for attaching the flywheel. Gears of gas distribution drive and water pump are secured on front end of shaft.

Diesels connecting rods stamped from carbon steel, rod of I-rod. Bronze bushing is pressed into upper head of connecting rod. The lower head of the connecting rod is detachable, the plane of the connector is located at an angle of 45 ° to the rod of the connecting rod. The cover of the lower head is stamped steel, attached by two bolts screwed into the connecting rod body. Inserts of the lower head of the connecting rod are made of aluminum-nickel alloy.

Piston of two-cylinder engines cast, cast iron;

Six piston rings are installed on the piston, four of which are rectangular compression rings, two are oil-removable. All rings are cast iron, the upper compression ring is chrome. Piston pin of steel, cemented floating type.

Gas distribution

The engine has one steel distribution roller, forged. For both two-cylinder engines, it is forged together with cams of inlet, outlet valves and fuel pumps. The profile of the inlet and outlet cams is the same. Distributing roller is installed on two ball bearings and is driven from crankshaft through gear train. On the distribution roller of the four and six-cylinder engines for driving the fuel pump, a gear is installed. Camshaft of engines is installed in bronze bearings.

Fuel supply system

Engine fuel system consists of filter, high-pressure fuel pump, nozzles and pipelines. No booster pump is installed on two-cylinder engines.

Filters. In the engine fuel system, a felt filter is installed, a slot filter is installed on the nozzle.

T o l and in n i high pressure pump. Individual single-plunger pumps are installed on the two-cylinder engines. The amount of fuel supplied is controlled by changing the supply end by rotating a pump plunger having a spiral cut-off edge on the cylindrical surface. Individual fuel pumps are driven from distribution roller. Drive roller of unit fuel pump with distributing roller of engine is connected by means of gears, and with cam roller of fuel pump by means of elastic coupling.

Closed type nozzle with pin sprayer. Needle opening pressure 140 5 kG/cm2. Nozzle hole diameter is 1.5 mm. Pin cone angle 15 °.

Regulator

Regulators of one of two types are installed on the engine:

1) all-mode centrifugal precision regulator of HLR, direct action with elastically connected cataract and variable degree of non-uniformity. The regulator is installed on engines designed to connect to alternators operating in parallel on a common network;

2) single-mode limit regulator, which allows insignificant adjustment of the number of revolutions.

Lubrication system

Engines lubrication system includes:

1) gear-type oil pump, for one- and two-cylinder engines is installed at the front end of the engine and is driven from the crankshaft through the shank,

2) filter of main cleaning of reticular type;

3) diaphragm type oil cooler,

4) fine filter with cardboard cartridge DASFO1,

5) screen receiving filter in tray. The pump sucks oil from the tray through the intake filter and pumps it through the main filter to the oil line and fine filter. The pressure in the system is 1.5 - 3 kG/cm2.

Cooling system

The engine cooling system may be closed, double-circuit or flow-through depending on the purpose of the engine. At flow cooling system, engines are equipped with one circulating water pump of vortex type, with gear drive from crankshaft installed on attachment cover of units. With closed cooling system, engines are supplied with additional centrifugal pump of sea water, which pumps water through heat exchanger. This pump is installed on the attachment cover of the units and is driven from the roller by a parasitic gear, with which the tail of the roller of the water pump engages. The circulating water pump pumps water into the central main line of the blockcarter, from where water enters the carved space of the cylinders and flows into the cavity of the cylinder cover, and then into the drain pipeline. The four- and six-cylinder engines cool down the exhaust manifold. Thermostat is installed in refrigerator end face.

Start-up system

Start of 2H 10.5/13 engines is performed manually. In addition, the engines are equipped with an electric start-up. Electric starting system includes starter ST25, storage battery 6 STE144 or 6STE128, charging generator GSK1500, voltage relay and filament plugs.

Calculation and construction of a theoretical indicator chart

The calculated indicator diagram is built based on the calculation data of the working cycle. In the future, this diagram is the starting material for dynamic and strength calculations of the engine. Chart construction is done analytically because graphical construction methods produce large errors.

Ordinates of points of compression and expansion polytrope are calculated by

Using the V/Vc ratio as a variable allows you to simplify the calculations, since the numerical values ​ ​ of V/Vc necessary for calculating the ordinates of the compression and expansion polytrop are mainly integers (from 1.0 to g for the compression polytrop, from p to e for the expansion polytrop). It is also convenient to set the same values of V/Vc to calculate the ordinate of the compression and expansion polytrop. At the same time, two ordinates of compression and expansion polytropes correspond to one abscissa, which greatly simplifies their construction.

The theoretical indicator diagram of the working cycle in this case is represented in the coordinate system p - V/Vc dimensionless in the direction of the axis of volumes. Absolute volumes corresponding to the V/Vc ratio values are easily found by multiplying the V/Vc ratio by the constant compression chamber volume Vc :

- for four-stroke ICE

Calculation of ordinates of points of compression and expansion polytropes is conveniently carried out in tabular form and in certain order

The values of ps, pa, pz and pp are control values and must correspond to those obtained in the calculation of the cycle.

Building an Indicator Chart

Dynamic calculation of the engine

Inertia Forces

Force of inertia of translational moving masses is applied in center of piston pin acts along cylinder axis and is equal to:

Gas pressure forces

The piston on the side of the combustion chamber is influenced by the pressure of gases in the cylinder of the engine Rg (Fig.2.). It is applied in the center of the piston pin and acts along the axis of the cylinder.

The gas pressure forces acting on the piston Rg and on the cylinder cover Rg are mutually balanced inside the engine and are not transmitted to its supports. Outside the engine, the pressure forces of the gases are manifested in the form of the rotating MIR and the overturning moments of the MOTAPM. The relative value of the pressure force of gases depending on the angle of rotation of the crank Pg = f (¼) is determined analytically or graphically from the calculated or actual indicator diagram .

It is more advantageous to analytically determine the working fluid pressures for the calculated crank positions. In this case, the following data should be available:

and e is the conditional and actual compression ratio;

and - the degree of preliminary expansion and the degree of subsequent expansion;

Pz and Pa - cylinder pressures - maximum and at the beginning of compression;

n1 and n2 - indices of compression and expansion polytropes;

The calculated positions of the mechanism and their corresponding values ​ ​ will be marked with index i; S * and s * without indices are used to indicate the full stroke of the piston.

The current compression ratio i is the ratio of the volume of the cylinder at the moment of the beginning of compression to its current volume, equal to the ratio of the pistons corresponding to these volumes:

Absolute value of gas pressure force on piston Rg = pgFn, MN, and relative value Rg = p, MPa.

Driving force

The driving force is the resultant of all the forces acting on the piston - the pressure force of the gases in the cylinder Rg, the air pressure force in the sub-piston cavity Rp, the inertia force of the PDM Pj, the gravity force and the PDM Rt and is equal to their algebraic sum, MPa,

Figure 2 shows the driving force in KSM. It is applied in the center of the piston pin and acts along the axis of the cylinder. Force Pdv is spread out into components: normal force acting perpendicular to the cylinder axis and pressing the piston to the bushing N = Pdvtg, and force acting along the connecting rod axis, Q = Pdv/cos.

The force Q is transferred along its line of action to the center of the connecting rod neck and is laid out into two components: the radial force acting on the crank, Z = Q cos (¼ +) = Pdb cos (¼ + )/cos and the tangential force T = Q sin (¼ +) = Pdb sin (¼ + )/cos.

The forces acting on the CMM are variable in magnitude and direction, therefore, for ease of analysis, they are represented in the form of graphical dependencies showing the change in forces along the angle of rotation of the crank. Periodic curves, with a period of 360 ° in two-stroke engines and 720 ° in four-stroke engines. The forces are considered positive when Rdv, Pj and Z are directed to the center of rotation of the crankshaft, T is directed to the side of rotation of the crankshaft, and N is directed to the side opposite to rotation. The angle is positive when the connecting rod is deflected towards the crankshaft rotation.

Total tangent forces in

multi-cylinder engine

The total tangent forces in multi-cylinder engines must be known in order to determine the torque and calculate the crankshaft for strength.

The diagram of the total tangent forces T of the multi-cylinder engine is constructed by sequentially summing the tangent force curves of each of the cylinders shifted in phase by the angle of the wedge of the cranks. Summation can be done graphically or in tabular form. Builds T.

The values of T are obtained by summing ordinates within each row. Values of Tz = T0, as T - periodic function with the period ϕз. According to the obtained data, we build a dependence T = f (¼).

Conclusions

In this work, I constructed an indicator diagram for the 2H 10.5/13 engine, which also made it possible to find gas pressure forces, inertia forces, driving forces, radial, lateral and tangent forces. These forces determine the design and, accordingly, the weight and size of the diesel engine. Finding tangent forces made it possible to find a change in torque on the flange of the engine. Since this is a ship's engine, by setting the degree of non-uniformity of rotation we can find the geometric dimensions of the flywheel using the dependence of the change in the total tangent force on the angle of rotation of the crankshaft

List of literature used

1. Istomin P.A. Dynamics of ship ICE. L. Shipbuilding, 1964.

2. Fomin Yu.A. and others. Ship ICE. L., Shipbuilding, 1989.

3. Gogin A.F. and others. Ship diesel engines, M., Transport, 1988.

4. Khandov Z.A. Ship ICE, M., Transport, 1968.

5. Vansheidt V.A. Ship ICE, Shipbuilding, 1962