Easy step by step guide on how an automotive internal combustion engines work,
though appearances may vary to concept is the same for most engine.
- An internal combustion engine is designed
to compress and use combustion of a fuel air mixture.
Automotive Internal Combustion Engine Cutaway - The engine begins by pulling air through
the air intake throttle actuator which is controlled via the
, and foot actuator that is located in the drivers compartment. This
air flow is monitored by the
mass air flow sensor
and cleaned by the
Electronic Throttle Actuator - Once air has passed through the throttle
actuator, it enters the intake manifold were it is divided among individual cylinder
Intake Manifold - Air is then routed through the intake
manifold were it enters individual intake ports contained within the
Step 4 cylinder head
which is controlled by a valve (intake.)
Intake Port Cutaway - Fuel enters the intake port or directly
into the combustion chamber via a
Step 5 fuel
which is controlled by the computer.
Port Fuel Injector
- A camshaft is used to open each valve
while it rotates as the engine is operating. A spring returns the valve to the closed
position which is called a "valve spring". (Overhead camshaft configuration shown.)
Camshaft - The
camshaft is connected to the engine crankshaft via a timing chain. As the crankshaft
turns, the chain is pulled while turning the camshaft at a 2 to 1 ratio 2:1. (Crankshaft
turns twice to once of the camshaft.) A
camshaft actuator is used to control the angle in which the camshaft is positioned
compared to the crankshaft. This position is controlled by the computer.
Timing Chain - A timing chain tensioner is used to take
up slack which helps keep the chain tensioned. This tensioner is activated by engine
Timing Chain Tensioner - The timing chain is driven at the crankshaft
using a drive gear near the front seal and harmonic balancer.
Crankshaft Driven Timing Chain - Once the fuel air mixture has entered
the combustion chamber the piston is thrust upward compressing the mixture for ignition.
Combustion Chamber Cutaway - After the fuel air mixture is compressed,
an Step 11 ignition
coil supplies a high voltage, low amperage charge to the spark plug.
Ignition Coil - This operation is controlled by the computer
which gathers data from the
crankshaft position sensor (CKS), camshaft angle sensors (CAS) and other various
Crankshaft Angle Sensor - After this flammable charge has been
compressed, an electronic charge crosses the spark plug, igniting the mixture which
then forces the piston downward.
Spark Plug (Block and Cylinder Head Cutaway) - As the piston is thrusting downward the
energy is contained within the crankshaft via the piston rods.
Pistons (Engine Block Cutaway) - The piston rod is designed to transfer
energy to a rotating crankshaft which is created by the piston.
Piston Rod - The crankshaft is supported along the
engine block and each piston rod attaches to it. Bearings, which are oiled, are
then fitted between rotating surfaces.
Crankshaft (Block Cutaway) - Once the intake charge has been spent,
the exhaust valve opens while the piston is thrust upward, forcing exhaust gases
to be removed from the cylinder and into the exhaust manifold.
Exhaust Valves (Block - Cylinder Head Cutaway) - While the crankshaft is rotating seals
are used to control motor oil from leaking from the engine oiling system.
Front Crankshaft Seal - An oil pump is driven from the crankshaft
or camshaft and is located in or near the oil pan of the engine. This pump circulates
oil under pressure throughout the engine to prevent heat through lubrication among
bearing and piston surfaces.
Oil Pump - Oil pressure is monitored by an oil pressure
sender, oil is also cleaned by and
Step 20 oil
filter which should be serviced regularly.
Oil Pressure Sender with Filter - Coolant is used to cool the engine while
in operation. A
Step 21 thermostat
is used to stop the coolant from flowing to the radiator until the engine is at
Coolant Thermostat - A water pump is used to circulate coolant
throughout the block, cylinder head and
Step 22 cooling
Water Pump - Together these parts create the engine
which rotates while consuming fuel.
Engine Operating (Animation)
Engine's are designed to have any number of cylinders and are created in all
sizes. The pistons are designed to fire consecutively to rotate the crankshaft inside
the engine block. Motor oil is used to cool and lubricate internal engine parts
including the crankshaft, camshaft, cylinders, pistons, piston rings, wrist pin,
lifters, rock arm, followers, intake and exhaust valves, timing gears and chain.
The oil then travels back into the oil pan creating a re-circulation system. The
oil pump determines the amount of oil pressure the engine will have via a pressure
spring fitted into a relief valve of the pump.
There are primarily two styles of valve train systems, "overhead cam" which consists
of a camshaft mounted on top of the cylinder head, and "in block" systems
which consist of a camshaft mounted inside the engine block, designs to perform
this action will vary depending manufacturer. The cylinder head is bolted to the
engine block using a gasket to seal the engine parts together.
An engine's power output rating is known as horsepower, which has been rated
differently in the past. A more standardized system is used today. Acceleration
is the process of changing the rate of velocity or movement of a vehicle, when a
turbocharger or supercharger accompanies
the engine, it increases the rate of acceleration by increasing horsepower.
The compression ratio of an engine is the measurement of how many times the volume
of the combustion chamber can be fitted into the cylinder when the piston is at
the bottom of its stroke. The compression ratio determines the octane required for
optimum performance and dictates the rate in which fuel that can be compressed without
self igniting. If self ignition does occur, its represented by an engine "ping"
or "knock" sound. Manufacturers create automobiles with improved horsepower and
lighter, stronger construction. This combination improves vehicle performance with
increased mileage. The measurement of horsepower has been successfully used to motivate
Horsepower was first conceptualized by James Watt, in 1782. This well known 19th
century engineer developed the term while observing a horse working on a treadmill.
With some calculations, he determined one unit of horsepower was equal to a specific
amount of work a horse could perform in a given amount of time. This method similar
to calculations used today.
Watt associated this new term to describe the power of a steam engine which would
be used for farming.
Neglect of scheduled
oil changes result in premature engine failures Cooling system neglect causing
in premature engine failures
Article first published