Function

Function

Oil pan




The main task of the oil sump is to be the reservoir for the oil as well as for part of the cylinder block. There are a number of components which are secured in or on the oil sump.
The oil level is checked via the dipstick which is connected to the oil pan. A suction pipe with a nozzle supplies the oil pump with oil which is then pumped onwards in the engine. To facilitate the suction function of the oil pump, there is a bleed valve which ensures that any air in the system is evacuated. The oil flows through the oil cooler to lower its temperature. The oil cooler is screwed to the outside of the oil pan.

Crankshaft
The function of the crankshaft is to transfer the upwards and downwards power of the piston movement. The engine is pendulum mounted, which provides better crankshaft balance than a non-pendulum mounted engine. The connecting rod, which is secured on the crankshaft, transfers the upwards and downwards movement of the piston into crankshaft rotation.

Piston
The main task of the piston is to compress the fuel/air mixture during the different strokes. The piston rings provide a seal so that the fuel/air mixture is not forced past the piston. The uppermost ring expands when the piston moves downwards. The second ring, as well as sealing is an oil scraper ring during the downward piston movement. The third ring ensures that the oil is drained via the drainage hole.

Camshafts, valve system




The camshafts and their valves let in the fuel and air mixture so that the ignition procedure can take place. The camshafts and their valves let out the fuel and air mixture after ignition has taken place. Tapered valve springs enables the use of a smaller valve washer and the total movable mass is reduced. The valve spring acts progressively, which gives a small force at the beginning of opening and end of closing, while it becomes big at the maximal valve lift.
The camshaft is rotated by the timing belt which is turned by the crankshaft. When the cam lobes on the camshaft press in the valve lifter, the valve is also pressed in and lets the fuel/air mixture out. A VVT unit on the camshaft can vary the valve timing steplessly using the oil pressure. The function of the VVT unit is to determine when to open or close the valves (within specific tolerances).

Mechanical belt tensioner




The belt tensioner must maintain constant pressure on the timing belt and prevent the belt from jumping off the cogs.

Lubrication system




The oil is led from the oil pan via a suction piece to the oil pump. The oil pump is located on the cylinder block. The oil is then pumped onwards to the oil cooling system and then to the oil filter.
The oil flows from the filter through a cast oil duct in the intermediate section to the main bearings. The oil then flows through bored channels in the crankshaft to the connecting rod bearings. The camshafts are supplied with oil by a bored channel in the cylinder block. The channel runs through the cylinder head, where it flows out at the bottom of the upper half of the cylinder head. There is a cross duct in the channel to the cylinder head which carries oil to the pistons via a piston cooling valve. The oil flows on via an oil duct to the bearing for the left-hand camshaft and the valve lifters (intake side).
The bearings for the right-hand side camshaft (exhaust side) are supplied by a cast cross duct at the front edge of the upper half. This cast cross duct also supplies pressurized oil to the solenoids for the VVT unit. Drain holes in the cylinder block release the oil from the cylinder head and crankshaft bearing back to the oil pan.

Oil filter




The filter is an environment filter which filters out any dirt particles from the oil. The oil flow from the outside into the filter. If the filter becomes blocked, the by-pass valve opens so that the oil can pass the filter. This ensures that the engine is always lubricated with oil.

Piston cooling valve




The piston cooling valve regulates the oil flow by letting oil through the piston cooling nozzles.

Oil pump




The oil pump pumps oil from the oil pan via channels in the intermediate section and cylinder block into the cylinder head and onwards in the system. The oil pump is placed on the crankshaft. A gear (duo-centric) reduces the flow of oil, increasing the pressure. This results in a pulse action which forces out the oil. The oil can only flow in one direction.

Intake system
Each cylinder has an intake manifold which comes from a plenum chamber. The injectors are on the lower aluminum intake manifold close to the intake valves. This is so that the fuel mixes as well as possible with the turbulent air. The position of the injectors is optimized to minimize wetting the cylinder walls. Thereby good emissions. There are ducts in the lower intake manifold for the crankcase gases so that they can reach the combustion chamber.




The air enters via the air intake, which is secured in the front member. In the inlet manifold, there is a rail that divides the pipe, to reduce the pressure-drop. Then the air passes in to the air filter housing. Here, there is also a so-called snow valve. This is opened if the air filter housing and air intake are clogged by snow. The air flow passes on and also cools the Engine control module (ECM) using cooling fins. The air flow continues on through a funnel and further to the mass air flow sensor. The mass air flow sensor measures the amount of air to the engine. Thereafter in a fresh air hose over the engine. Then the air passes the turbocharger and the charge-air cooler and continues to the electric throttle body and in to the inlet manifold. The EVAP-valve returns the fuel and air mixture for further combustion. The EVAP-valve is located by the throttle body.

Throttle body (TB)
The throttle body guides the air flow into the intake manifold. The requested throttle disc angle is obtained by the driver by the accelerator pedal movement / accelerator pedal position. The intake air comes from the air filter housing through the throttle body and on to the intake manifold.

Turbocharger (TC)
The exhausts enter via the manifold down to the turbine housing and out to the exhaust system via downpipe and the catalytic converter. The turbine rotor blows out the exhausts and gives rotation to the compressor rotor. The compressor rotor generates a certain suction for inlet air. This inlet air enters via the air filter in to the compressor and that speeds up the air via a rotational movement, it is this that generates the boost pressure. Then the air continues to the inlet system. The wastegate controls the turbocharger's boost pressure by deciding how much of the exhausts shall pass through the turbine, which then transfers power to the compressor. The by-pass valve is a diaphragm that balances inlet and exhaust air pressure to eliminate any noise.

Crankcase ventilation
The crankcase ventilation controls the pressure in the crankcase. The crankcase gases are also separated in the flame trap and cyclone separators and favorable particles are returned to the engine.

Flame trap
The flame trap roughly separates the crankcase gases from the cylinder block. The crankcase gases circulate around the walls in the flame trap before entering the cyclone separators. The cyclone separators act on the crankcase gases to separate the particles/substances. The oil in the crankcase gas runs down into a container chamber to be returned to the oil pan. The rest of the crankcase gas is directed on to a pressure regulator which regulates the pressure in the crankcase. The crankcase gas is then evacuated from the pressure regulator to return to the intake manifold via the turbocharger on vehicles with turbocharged engines. Otherwise the gas returns directly to the intake manifold.

Oil cooler
When the coolant temperature is high enough to partially open the thermostat, the coolant is distributed via the radiator and the bypass channel to the coolant pump. When the thermostat is fully open, all the coolant goes to the radiator. The cooled air is sucked through the radiator by an electric engine cooling fan (FC) on the fan shroud behind the radiator.

Thermostat
The thermostat controls the amount of coolant to the engine. When energy in the form of heat is added, the wax body expands. In today's cooling system the thermostat is set to start expanding when the ambient coolant temperature is 90 °C. When the wax body in the thermostat starts to expand it enables a flow of coolant through the radiator, at the same time as it shuts off the flow to the by-pass, to obtain faster cooling. The coolant returns back in to the engine, without being cooled, through the by-pass. Any air can escape from the system with a jiggle pin. The jiggle pin is located in the thermostat.