Читать книгу Internal Combustion Engines - Allan T. Kirkpatrick - Страница 35

A photograph of a V‐6 3.2 L automobile engine is shown as in Figure 1.19 and in cutaway view in Figure 1.20. The engine has a 89 mm bore and a stroke of 86 mm. The maximum power is 165 kW (225 hp) at 5550 rpm. The engine has a single overhead camshaft per piston bank with four valves per cylinder. The pistons are flat with notches for valve clearance. The fuel is mixed with the inlet air by spraying the fuel into the intake port at the Y‐junction just above the intake valves.

Figure 1.19 3.2 L V‐6 automobile engine. (Courtesy of Honda Motor Co.)

Figure 1.20 Cutaway view of 3.2 L V‐6 automobile engine. (Courtesy of Honda Motor Co.)

As shown in Figure 1.21, the overhead camshaft acts on both the intake and exhaust valves via rocker arms. The engine has variable valve timing applied to the intake valves with a shift from low‐lift short duration cam lobes to high‐lift long duration cam lobes above 3500 rpm. In the low‐lift short duration cam operation the two intake valves have staggered timing, which creates additional swirl to increase flame propagation and combustion stability. Roller bearings are used on the rocker arms to reduce friction. The clearance volume is formed by an angled pent roof in the cylinder head, with the valves also angled.

Figure 1.21 A variable valve timing mechanism. (Courtesy of Honda Motor Co.)