Pc42b Design

The latest version of the 570 mm bore PC4 series, the PC4-2B design, has a 660 mm stroke and develops 1325 kW/cylinder at 430 rev/min on a mean effective pressure of 22 bar. The production programme embraces V10-, 12-, 16- and 18-cylinder models covering a power band up to 23 850 kW (Figures 25.2 and 25.10). A specific fuel consumption of 176 g/kWh is reported. Progressive improvements have benefited the PC4 design since the first example entered service in 1977, the refinements focusing on the exhaust and inlet manifolds, exhaust valves, fuel injection system, crankshaft and camshafts. The PC4-2 featured a 620 mm stroke and the PC40L (Figure 25.11) a stroke of 750 mm and a running speed of 375 rev/min.

Fuel Injector Cross Section
Figure 25.10 Cross-section of PC4-2B engine
Figure 25.11 Cross-section of PC40L engine

The key features of the PC4-2B engine include:

• A one-piece welded steel engine frame with a steel plate oil sump mounted on the bottom.

• A bore-cooled cylinder liner of special cast iron located inside a cast iron water jacket, avoiding contact between the cooling water and the engine frame. Cooling of the liner's upper part was calculated to reduce thermal stresses.

• A one-piece underslung crankshaft of chromium molybdenum forged steel; each main bearing is fixed by two vertical and two horizontal tie-bolts, fostering a weight reduction for the frame. A temperature sensor is installed on each main bearing to prevent shell bearing abnormalities.

• Composite-type pistons embrace a steel crown and light alloy skirt, with a floating-type piston pin. The crown is oil cooled by the shaker effect.

• Forged alloy steel connecting rods with a wide big end and stepped boss small end to secure low bearing pressures.

• The cast iron cylinder head is fixed to the water jacket and to the liner by eight studs screwed into the frame bosses. It incorporates two inlet and two exhaust valves, a fuel valve, an indicator valve, a safety valve and a starting valve.

• Heat-resistant steel inlet valves exploit the two-guides solution while the Nimonic exhaust valves have sealed guides. All water flowing across the cylinder head runs through the exhaust valve cages, significantly reducing the valve seat temperature. All the valves are provided with Rotocap rotating devices.

• Camshaft bearings are fixed directly under the fuel injection pump brackets, avoiding the transmission of injection stresses to the frame.

• A large fuel injection pump diameter and short piping underwrite a high injection pressure achieving fine fuel pulverization even at low load; complete and clean combustion of the heaviest residual fuels with a high asphaltene content is promoted. The fuel pump plunger and barrel can be exchanged through the pump's upper part without dismantling the pump body. The weight of the dismountable equipment is 20 kg. The fuel injectors are cooled by a separate freshwater circuit.

• The patented modular pulse converter (MPC) turbocharging system is the best compromise between pulse and constant pressure systems, according to SEMT-Pielstick. Air coolers may be supplied with two banks of tubes, one of which can be deployed to heat air when the engine operates at low load.

See Chapter 22 for MAN B&WDiesel's V40/50 design, a derivative of the SEMT-Pielstick PC2.6B engine; and Chapter 30 for SEMT-Pielstick PA series high speed engines.

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