The exhaust camshaft is driven by a roller chain from the crankshaft sprocket (pic. 3.13), intake camshaft - from the exhaust sprocket, thanks to an intermediate goal.
1 - crankshaft; 2,8,14,15 - asterisk; 3 - tensioner bar; 4 - piston; 5 - spring; 6 - sealing ring; 7 - cover bolt; 9.16 - chain; 10.12 - strap bolt; 13 - key; 17 - exhaust camshaft; 18 - intake camshaft; 19 - hydraulic pusher; 20 - valve cotters; 21 - top plate; 22 - spring; 23 - bottom plate; 24 - oil scraper cap; 25 - inlet valve; 26 - exhaust valve
Gas distribution mechanism (timing) includes a cylinder head, camshafts, intake and exhaust valves, valve guides, conical valve springs with fastening parts, hydraulic tappets, camshaft drive targets with tension and damping parts. The tension of the chains is regulated by an automatic tensioner with a hydraulic damping mechanism.
Camshafts (17 and 18) valve actuators (25, 26) have a mechanism for changing the angle of their initial position (turn), which leads to a change in the opening phase of the valves - the D-VANOS system. Gas distribution mechanism (timing) includes a cylinder head, camshafts, intake and exhaust valves, valve guides, conical valve springs with fasteners, hydraulic pushers, camshaft drive chains with tension and damping parts.
The chain tension is regulated by an automatic tensioner with a hydraulic damping mechanism.
Camshaft
Camshafts (17, 18. fig. 3.13) seven basic, rotate in plain bearings.
Sprockets mounted on exhaust camshafts (8. 14, 15) for drive chains (9,16). The sprockets are connected to the camshafts through the inclined splines of the D-VANOS mechanism, which allows you to change the position of the shafts during engine operation.
Axial movement of the camshaft:
- nominal 0.150 mm;
- maximum allowable 0.330 mm.
Gap between shaft journals and their bearings (radial): 0.02—0.054 mm
Limit runout in operation 0.1 mm.
Thrust bearing width 20.0 mm.
Camshaft lobe height:
- inlet 47.7±0.06 mm;
- outlet 46.8±0.06 mm.
Valve lift:
- intake 9.7 mm;
- outlet 8.8 mm.
The maximum permissible diameter of the camshaft journals in operation (before renovation) - 34.86-0.02 mm.
Camshafts of nominal size are marked with blue paint, repair size - yellow. The mark is applied between the first and second cams.