Open large image in new tab »
1. Crankshaft. 2. Crankshaft sprocket. 3. Chain stop pin. 4. Camshaft drive chain. 5. Chain tensioner shoe. 6. Chain tensioner plunger. 7. Chain tensioner plunger spring. 8. Chain tensioner rod. 9. Clamping cracker of the rod. 10. Fixing nut. 11. Chain tensioner spring. 12. Bolt of fastening of an asterisk. 13. Camshaft sprocket. 14. Chain guide. 15. Thrust flange of the camshaft. 16. Camshaft bearing housing. 17. Camshaft. 18. Retaining ring. 19. Inlet valve. 20. Intake valve guide. 21. Oil cap. 22. Support washer of the outer spring of the valve. 23. Support washer of the internal valve spring. 24. Internal valve spring. 25. Outer valve spring. 26. Valve spring plate. 27. Valve cracker. 28. Valve drive lever. 29. Valve lever spring. 30. Valve adjusting bolt. 31. Adjusting bolt locknut. 32. Adjusting bolt bushing. 33. Exhaust valve. 34. Exhaust valve guide. 35. Insert connecting rod bearing. 36. Nut of fastening of a cover of a rod. 37. Connecting rod cover. 38. A bolt of fastening of a cover of a rod. 39. Connecting rod. 40. Piston pin. 41. Piston. 42. Top compression ring. 43. Lower compression ring. 44. Oil scraper ring. 45. Oil scraper ring spring. 46. Heat-regulating piston plate. 47. Flywheel bolt. 48. Washer of bolts of fastening of a flywheel. 49. Flywheel. 50. Front bearing of the input shaft of the gearbox. 51. Half rings of the thrust bearing of the crankshaft. 52. Inserts 1, 2, 4 and 5 of the main bearings. 53. The insert of the central main bearing.
The energy of the expansion of the products of combustion of fuel through the crank mechanism is transmitted to the crankshaft of the engine. The details of the crank mechanism are exposed to significant mechanical and thermal loads. The selection of materials for the piston, pin, piston rings and their design provide reliable cylinder sealing, efficient heat dissipation, low weight of parts, minimum friction coefficient, high strength and reliability.
Pistons 41 are made of aluminum alloy and coated with a layer of tin to improve run-in. The piston skirt is oval in cross section, and the major axis of the oval is perpendicular to the axis of the piston pin. The piston has a conical shape in height: the diameter is smaller at the top than at the bottom. In addition, steel plates 46 are poured into the piston bosses. All this is done to compensate for the uneven thermal deformation of the piston during operation in the engine cylinders, which occurs due to the uneven distribution of the metal mass inside the piston skirt.
Piston bosses have holes for oil to pass to the piston pin. The hole for the piston pin is shifted from the axis of symmetry by 2 mm to the right side of the engine. This reduces the possibility of piston knocking when passing through top dead center.
Pistons are subdivided into five classes according to the outer diameter through 0.01 mm and individually selected for each cylinder, and according to the diameter of the hole for the piston pin - into three categories through 0.004 mm.
Pistons by weight in the same engine are selected with a maximum allowable deviation of±2.5 g.
The piston pin 40 is steel, cemented, tubular section, pressed into the upper head of the connecting rod with an interference fit and rotates freely in the piston bosses.
Piston pins, like the holes in the piston bosses in terms of outer diameter, are divided into three categories through 0.004 mm. The pin and piston to be assembled must belong to the same category.
Piston rings 42, 43 and 44, which provide the necessary sealing of the cylinder, are made of cast iron. The piston has two compression (sealing) rings that seal the gap between the piston and cylinder and remove heat from the piston, and one oil scraper, which prevents oil from entering the combustion chamber. The rings are pressed against the cylinder wall by their own elasticity and gas pressure. The upper compression ring 42 operates under conditions of high temperature, aggressive combustion products and insufficient lubrication, therefore, to increase wear resistance, its outer surface is chrome-plated and has a barrel-shaped generatrix to improve running-in. Bottom Compression Ring 43 Scraper Type (has a groove on the outer surface) phosphated, also performs the additional function of an oil-drop ring.
The oil scraper ring 44 has slots for the oil removed from the cylinder and an internal twisted spring 45 - an expander that provides additional pressing of the ring against the cylinder wall.
Connecting rods 39 - steel, forged with an I-section rod. The lower head of the connecting rod is detachable; inserts 35 of the connecting rod bearing are installed in it. The lower head cover 37 is fastened with two bolts 38 and self-locking nuts 36. The connecting rod is processed together with the cover, and therefore, during assembly, the numbers on the connecting rod and the cover must be the same and be on the same side.
Oil passes through the hole at the transition point of the lower head of the connecting rod to the rod, lubricating the cylinder walls.
The crankshaft 1 is cast iron and is the main power part of the engine, which perceives the action of gas pressure and inertial forces. The shaft material works for fatigue. An increase in fatigue strength is achieved by a large overlap of the main and connecting rod journals, the presence of five bearings (full support), surface hardening of the necks with high-frequency currents to a depth of 2-3 mm, specially made transitions between the necks and cheeks, careful processing of stressed areas.
Lubrication from the main bearings to the connecting rods is supplied through drilled channels, which are closed with plugs 54. Axial movement of the crankshaft (no more than 0.35 mm) limited by two thrust half rings 51 located in the block on both sides of the rear main bearing. It should be borne in mind that the grooves located on one side of the semi-rings 51 must face the thrust surfaces of the crankshaft.
At the rear end of the crankshaft, a socket is made for the front bearing 50 of the gearbox input shaft.
Flywheel 49 is cast iron and has a pressed steel gear rim for starting the engine with a starter. The flywheel is attached to the rear end of the crankshaft with six bolts 47, under which a washer 48 is installed.
The liners of the main 52, 53 and connecting rod 35 bearings are thin-walled, bimetallic steel-aluminum. The shells of each main or connecting rod bearing consist of two halves. The bushings are kept from turning by a protrusion that enters the groove of the connecting rod or main bearing. All connecting rod bearings are identical and interchangeable. Inserts 52 of the 1st, 2nd, 4th and 5th main bearings are the same and interchangeable, the insert 53 of the central (3rd) the main bearing differs from the rest in width.
The gas distribution mechanism ensures that the engine cylinders are filled with a fresh charge of the combustible mixture and the exhaust gases are released.
The parts of the gas distribution mechanism include: camshaft, valves and guide bushings, springs with fastening parts, valve drive levers. The gas distribution mechanism is driven from the drive sprocket 2 of the crankshaft 1 by a double-row roller chain 4. The same chain drives the oil pump drive shaft, ignition distributor and fuel pump through the second sprocket. A feature of the drive is the use of a semi-automatic tensioner (including tensioner and its shoe) and chain damper 14.
To adjust the chain tension, it is necessary to unscrew the fixing nut 10. In this case, the chain is tensioned by the shoe 5, on which the spring 11 acts through the plunger 6. The tensioner shoe rotates around the fastening bolt. After tightening the nut 10, the rod 8 is clamped by the collets of the cracker 9, as a result of which the external tensioner spring is blocked. During operation, only the internal spring 7 acts on the plunger 6, which, due to a gap of 0.2-0.5 mm in the tensioner mechanism, provides compensation for chain vibrations. The chain damper 14 with a rubber pad dampens the vibrations of the leading branch of the chain. A restrictive pin 3 is installed at the bottom of the cylinder block, which prevents the chain from falling into the crankcase when the camshaft sprocket is removed from the car.
The camshaft 17, which controls the opening and closing of the valves, is cast iron, cast, with hardened high-frequency currents, rubbing surfaces of the cams and bearing journals. The driven sprocket 13 is attached to the front end of the camshaft with a central bolt 12. The camshaft rotates on five bearings in a special housing 16, mounted on the cylinder head at nine points.
From axial movements, the camshaft is held by a thrust flange 15, placed in the groove of the front bearing journal of the shaft. The thrust flange is attached to the camshaft bearing housing with two studs and nuts. Lubrication to the rubbing surfaces of the camshaft is supplied from the oil line through a groove on the central bearing journal, through drilling along the axis of the shaft and holes on the cams and bearing journals.
valves (intake 19 and exhaust 33), which serve to periodically open and close the openings of the intake and exhaust channels, are located in the cylinder head obliquely in one row. The intake valve head has a larger diameter for better cylinder filling, and the exhaust valve face, which operates at high temperatures in an aggressive exhaust gas environment, has a heat-resistant alloy overlay. In addition, the exhaust valve is made of composite: the stem is made of chromium-nickel-molybdenum steel with better wear resistance to friction and thermal conductivity to remove heat from the valve head to its guide sleeve, and the head is made of heat-resistant chromium-nickel-manganese steel. The inlet valve is made of chromium-nickel-molybdenum steel.
Springs (outer 25 and inner 24) press the valve to the seat and do not allow the valve to come off the actuator lever. The lower ends of the springs rest on two support washers 22 and 23. The upper support plate 26 of the springs is held on the valve stem by two biscuits 27, which, when folded, have the shape of a truncated cone.
The guide bushings 20 and 34 of the valves are made of cast iron, pressed into the head and are kept from possible falling out by retaining rings 18. The hole in the bushing is finally processed as an assembly with the cylinder head, which ensures a narrow tolerance for the diameter of the hole and the accuracy of its location in relation to the working chamfers seats and valves. To reduce the penetration of oil into the combustion chamber through the gaps between the sleeve and the valve stem, oil deflector caps 21 made of oil-resistant rubber are used.
The valve seats are made of special cast iron and pressed into the heated block head when cooled. Plug-in valve seats provide the necessary strength when subjected to shock loads. In order to obtain a secure fit of the valve seat in the bored seat of the block head at various expansion coefficients of the block head and seat materials, the seat is cooled to -180°C before pressing, and the cylinder head is heated to 170°C.
Levers 28, steel, transmit force from the camshaft cam to the valve. The lever at one end rests on the spherical head of the adjusting bolt 30 and is held by springs 29, and the other end, which has a special groove for holding the lever on the valve, rests on the end of the valve. The adjusting bolt 30 is screwed into the sleeve 32, which, in turn, is screwed into the cylinder head. The adjusting bolt is locked with a nut 31.