Kamaz Motor 740 - Drawings

Contents

Project Task ____________________________________ ___

Design Part

1. Description of the ____________________________ design ___

1.1. Engine ______________________________________ ___

1.2. Cylinder block and drive of units ______________ ___

1.3. Crank mechanism ___________________ ___

1.4. Gas distribution system ______________________ ___

1.5. Lubrication system _____________________________ ___

1.6. Fuel supply system _______________________ ___

1.7 Engine air supply and exhaust system

exhaust gases _____________________________ ___

1.8. Cooling system ____________________________ ___

2. Engine calculation _________________________________ ___

2.1. Workflow Calculation _______________________ ___

2.2.1 Dynamic calculation of engine ___________________ ___

2.3.1 Balancing of _______________________________ ___

2.3.2 Calculation of forces and moments acting in the engine _ ___

2.4. Strength calculation _____________________________ ___

2.4.1. Crankshaft calculation ______________________ ___

2.4.2. Calculation of connecting rod ________________________________ ___

2.4.3. Calculation of piston ring _____________________ ___

2.4.4. Calculation of piston pin ______________________ ___

2.4.5. Calculation of the thermal state of the piston _____________ ___

List of literature ___________________________________ ___

Project Task

Design a four-stroke supercharged six-cylinder diesel engine based on the KAMAZ740 engine for the main tractor of the road train, with the following characteristics:

• Crankshaft speed - 2400 rpm.

• Nominal compression ratio - 16

• Number of valves per cylinder - 4 pcs.

• Speed - 100 km/h.

• Carrying capacity - 25 tons

Install pressurizing system on the engine. Perform dynamic calculation. Perform thermal calculation and calculate strength of the following main parts:

• Connecting rod

• Crankshaft

• Piston ring

• Valve spring

• Piston

1. Construction Description

1.1 Engine

The 6CHN12/12 engine, based on KamAZ740.11-240, is a four-stroke liquid-cooled diesel engine with a V-shaped arrangement of six cylinders with an adjustable pressurizing system and cooling of air after the turbocharger.

The engine has design features:

• pistons cast from high-silicon aluminium alloy with cast iron reinforcing insert for upper compression ring and colloidal graphite in-line skirt coating;

• cylinder liners, volume hardened and treated with flat-top honing;

• piston rings with chromium and molybdenum coating of side surfaces;

• nitrated crankshaft;

• three-layer thin-walled stalebronic inserts of main and connecting rod bearings;

• high-efficiency filtration of oil, fuel and air with paper filtering elements;

• closed cooling system filled with low-freezing cooling liquid with automatic temperature control, fan drive hydraulic coupling and thermostats;

• electrophacel air heating device providing reliable starting of the engine at negative ambient temperatures up to minus 25 ° С.

1.2 Cylinder block and unit drive

Cylinder block is cast from alloyed grey cast iron integral with upper part of crankcase. The crankcase part of the unit is connected to the covers of the base supports by transverse bolting, which gives strength to the structure. To increase longitudinal stiffness, outer walls of the unit are curvilinear. Boss bolts for attachment of cylinder heads are lugs on transverse walls forming water jacket of block.

The left row of cylinders is shifted from the right forward by 29.5 mm, which is caused by the installation of two connecting rods on one crank journal of the crankshaft.

A cover covering the fan drive hydraulic coupling is attached to the unit in front, and a flywheel case is attached to the rear, which serves as a cover for the units drive mechanism located on the rear end of the unit.

"Wet" type cylinder liners are easily detachable, made of special cast iron, volume hardened to increase wear resistance.

The sleeve mirror is treated with flat-top honing to obtain a grid of cavities and platforms at an angle to the sleeve axis. This treatment helps to keep the oil in the troughs and to make the liner more workable.

In the connection of the liner - cylinder block, the water cavity is sealed with circular rubber rings. In lower part two rings are installed in bores of unit.

Gear drive with spur gears, gas distributing mechanism is actuated by drive gear installed with interference on crankshaft tail through intermediate gear unit. Block of intermediate gears rotates on twin conical roller bearing. Gear of camshaft is installed on shaft tail with interference. High-pressure fuel pump is driven by gear engaged with camshaft gear. Rotation to high-pressure fuel pump is transmitted through driving and driven half-couplings with elastic plates, which compensate for misalignment.

Gear of compressor drive and gear of rudder hydraulic booster pump drive are engaged with drive gear of fuel pump.

1.3 Crank gear

The crankshaft is steel, made by hot stamping, strengthened by nitriding or quenching by high-frequency currents of connecting rod and main necks.

Crankshaft has four main supports and three connecting rod necks. In crankpins of shaft there are internal cavities closed with plugs, where oil is subjected to additional centrifugal cleaning. Spaces of connecting rod necks communicate with inclined holes with transverse channels in main necks.

Oil pump drive gear and drive gear assembled with oil deflector are installed on nose and tail of crankshaft. Remote counterweights are detachable and secured on shaft by press fit.

Axial displacements of crankshaft are limited by four steel-aluminum semi-rings installed in grooves of rear root support so that side with grooves adjoins thrust ends of shaft, and hub enters slot on cover of rear root bearing.

Crankshaft shank is sealed by rubber self-tightening gland installed in flywheel case.

Flywheel made of grey special cast iron is fixed by bolts on rear end of crankshaft and is fixed by two pins and locating bushing. Toothed rim is fitted on flywheel by hot press fit and serves for starting of engine by starter. The number of teeth of the crown of the flywheel 113.

On the outer surface of the flywheel there is a slot for the flywheel retainer, which is used in adjusting the engine.

Connecting rods of steel, I-section; lower head is made with straight and flat connector. The connecting rod is finally processed together with the cover, so the connecting rod covers are not interchangeable. Two connecting rods are installed on each connecting rod journal of crankshaft. The sliding bearings are a bushing made of bimetallic tape in the upper head of the connecting rod and removable interchangeable inserts in the lower one. Connecting rod cover is secured by two connecting rod bolts with nuts.

Pistons made of high-silicon aluminum alloy with insert (special cast iron) for the upper compression ring and colloidal graphite skirt coating. Two compression rings and one oil-collecting ring are installed on the piston. Compression rings in section represent one-sided trapezoid, made of cast iron of special chemical composition. Working surface of upper compression ring is covered with chromium, lower one with molybdenum.

Oil collector ring of rectangular section with twisted spring expander and chrome working surface.

Combustion chamber is arranged in piston head. Piston with connecting rod is connected with pin of floating type, axial movement of pin in piston is limited by locking rings. Piston pin is made of chromium-nickel steel in the form of hollow cylindrical rod, hardened by cementation and hardening.

The bearings of the crankshaft and the lower head of the connecting rod are replaceable, thin-walled, three-layer, with a working layer of lead bronze. Upper and lower inserts of crankshaft crankshaft bearing are non-replaceable. Upper insert has oil feed hole and groove for its distribution.

1.4 Gas distribution system

Gas distribution mechanism is designed for air intake into cylinders and exhaust gas discharge. The opening and closing of the inlet and outlet valves takes place in strictly defined positions with respect to the upper and lower dead points, which correspond to the rotation angles of the crankshaft neck indicated in the gas distribution phase diagram.

Engine valve distribution mechanism - overhead valve. Cams of camshaft actuate pushers in certain sequence. Rods impart rocking movements to rockers, which, overcoming resistance of springs, open valves. Valves are closed by force of compressed springs. The improvement of the gas exchange system consists in the use of two inlet and two outlet valves.

Torque is transmitted to camshaft from crankshaft through gears of units drive.

Cylinder heads cast from aluminium alloy have coolant cavities communicating with block jacket. Joints of cylinder head and liner, head and unit are sealed with gaskets. A ring of gas joint is pressed into the groove on the sealing plane of the head, by which the head is directly installed on the collar of the cylinder liner. Sealing tightness is ensured by high accuracy of treatment of mating surfaces of ring and cylinder liner and, additionally, by application of lead coating on ring surface to compensate for micro-irregularities of sealed surfaces. Sealing of bypass channels for cooling liquid is performed by sealing rings made of silicone rubber, which are installed by shanks into holes of cylinder head. Head restraint space, hole of engine oil drain and rod passage are sealed by molded gasket of cylinder head.

Inlet and outlet channels are located on opposite sides of head. Inlet channel has tangential profile to swirl air in cylinder. Cast-iron seats and metal-ceramic guide bushings of valves are pressed into the head. Each head is fixed on the unit with four bolts. Valve mechanism is closed by aluminium cover under which sealing gasket is located.

Steel camshaft, surfaces of cams and support necks are cemented and hardened with high-frequency currents. The shaft is installed in the collapse of the unit on four sliding bearings.

The bearing of the rear support is a bushing clad with bronze and pressed into a removable cast-iron housing. Bushings made of bimetallic tape pressed into transverse partitions of the unit serve as bearings for other shaft supports.

Axial displacement of the camshaft is limited by the bearing housing, against the ends of which the gear hub rests on one side, and on the other side - the thrust collar of the rear support of the shaft journal. Rear support bearing housing is secured on the unit by three bolts.

Pushers - fungal type, hollow, with cylindrical guide part, are made by cold landing from steel with subsequent surfacing of the plate with bleached iron. Inner cylindrical part of pusher ends with spherical seat for stop of lower end of rod.

Inlet and outlet valves are made of heat-resistant steels. The rods of both valves are 125 mm long. from the end face they are coated with graphite to improve running-in.

During operation of the engine, the valve rods are lubricated with oil flowing from the coupling of the rockers with the axes and sprayed by the valve springs. To prevent oil ingress into the cylinder along the gap, a rubber collar is installed on the bushing of the intake valve.

Pusher guides cast from grey cast iron are made detachable to increase repairability and processability of the unit. Three guides are installed on the engine, in which three pushers move. Each guide is mounted on two pins and attached to cylinder block by two bolts. Bolts are locked by bending washers.

Pusher rods - steel, tubular, with pressed and compacted tips. Lower tip has convex spherical surface, upper tip is made in the form of spherical cup for stop of adjusting screw of rocker.

The rocker arm of the valve - steel, forged, with a bronze bushing, is a double-arm lever having a transmission ratio of 1.55. Adjustment screw with counter nut is screwed into short arm of rocker to adjust clearance in valve mechanism. Rockers of inlet and outlet valves are mounted cantilever on axles made integral with rocker strut; post is installed on pin and is fixed on head by two studs. Axial movement of rockers is limited by spring retainer. Lubricant is supplied to each rocker through holes in rocker strut.

Valve springs are cylindrical with uniform pitch of turns. and different winding directions. Two springs are installed on each valve. Lower ends of springs rest on head through. steel washer, upper ones - to plate. Trays rest against bushing connected with valve rod by two conical crumbs. The split bushing-tray connection allows the valves to rotate relative to the seat.

1.5 Lubrication system

Engine lubrication system combined with wet crankcase. Oil under pressure is supplied to crankshaft crankshaft and crankshaft bearings, camshaft bearings, rocker sleeves, high-pressure fuel pump and compressor bearings. Pulsed oil supply to upper spherical supports of push rods is provided.

lubrication system includes oil pump, oil crankcase, filters - full-flow and centrifugal, air-oil radiator, oil channels in cylinder block and heads, front cover and flywheel crankcase, external oil pipes, oil-filling neck, valves to ensure normal operation of the system and control devices.

Oil is supplied from crankcase through oil intake to oil pump delivery and radiator sections, from pressure section through channel in RH wall of block it is supplied to oil cleaning filter, where it is cleaned by two filtering elements, then it is supplied to main line, from where it is directed to crankshaft main bearings, rocker bushings and upper tips of pusher rods through channels in block and cylinder heads. Oil is supplied to crankshaft crankshaft bearings via holes inside the shaft from the nearest root journal. Oil removed from cylinder walls by oil-collecting ring is withdrawn into piston and lubricates supports of piston pin in bosses and bearing of upper head of connecting rod. Oil under pressure flows through channels in rear wall of cylinder block and housing of flywheel to bearings of compressor, through channels in front wall of unit - to bearings of high-pressure fuel pump. Oil is extracted from the main line for supply to the hydraulic clutch switch, which is installed on the front end of the unit and controls operation of the hydraulic clutch of the fan drive. Oil flows from the radiator section of the oil pump to the centrifugal filter, then to the radiator and then to the crankcase. When the valve is closed, oil from the centrifugal filter is drained into the crankcase through the drain valve, bypassing the radiator.

The remaining engine parts and assemblies are lubricated with spray and oil mist.

Oil pump is secured on lower plane of cylinder block. Pump delivery section supplies oil to engine main line, radiator section - to centrifugal filter and radiator. Oil cleaning filter installed on the right side of cylinder block consists of housing, caps and two paper filtering elements. Bypass valve with filter element clogging indicator is installed in filter housing. Signal lamp of filter elements clogging is located on the instrument panel in the cockpit. The lamp is allowed to glow or blink at engine starting and heating. At constant illumination of the lamp on the heated engine, replace the filtering elements.

Oil pressure and warning sensors [less than 68.7 kPa (0.7 kgf/cm2)] of oil pressure in the main line are installed in the filter housing.

The bypass valve bypasses the crude oil into the main line, bypassing the filter element, at low oil temperature or significant clogging of the filter elements with pressure drops on the elements 245.8... 294.2 kPa (2.5... 3.0 kgf/cm2).

Centrifugal oil filter - with active-reactive rotor drive, is installed on front cover of cylinder block on the right side of engine. Rotor assembled with hood is rotated by oil jet flowing from tangential slot in rotor axis, as well as by reactive forces generated at oil inlet into rotor tangential channels.

During operation of the engine, oil is supplied from the radiator section of the pump under pressure to the filter, ensuring rotation of the rotor. Under the action of centrifugal forces, mechanical particles are thrown to the walls of the rotor cap and retained, and purified oil through the hole in the rotor axis and the pipe enters the air-oil radiator or through the drain valve in the filter body, adjusted for pressure 49.0... 68.7 kPa (0.5... 0.7 kgf/cm2), in the engine housing. The bypass valve installed in the filter housing is adjusted to the pressure of 588.4... 637.5 kPa (6.0... 6.5 kgf/cm2).

In order not to disturb the rotor balance during the filter maintenance, the rotor and the hood are marked, which must be combined during its assembly.

Oil stamped steel crankcase is secured on lower plane of cylinder block by bolts. Rubber-plug gasket is installed between crankcase and unit to ensure tightness of connection. In the lower part of the crankcase there is a drain plug.

Air-to-oil tube-plate radiator, two-row air-cooled radiator is installed in front of engine cooling system radiator.