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Automotive - 4 Stroke Engine Terms
Terms in this set (35)
Internal Combustion Engine
Power comes from the burning of a compressed mixture of gasoline and air in a proper ration. It is the burning of this chemical energy and transforming it into mechanical energy that takes place in this assembly
Pushes valves open using an eccentric lobe
Allows air to enter the combustion chamber when the correct valve/valves are open. It may also be where fuel is mixed with the air.
Is the device that controls air entering, and prevents it leaving from, the combustion chamber. it should only be open during the intake stroke
where controlled burning of the air/fuel mixture takes place.
Holds the Crank Shaft, Cylinders, & has many other components mounted to it.
Physical link between the crankshaft and piston
Part in an engine the ultimately changes the linear up and down motion of the pistons into rotational motion
Performs the task of compressing the air/fuel mixture as it is moving up and is pushed down by the expanding gas once it is ignited.
Usually exists in a 50/50 mixture and helps transfer heat created during the combustion process out of the engine and into the air. It also helps lubricate the water pump and prevents freezing at cold temperatures.
On most engines, it holds most of the valve train. It is bolted to the top of the engine block and helps create the combustion chamber. It also has passages for coolant and oil to circulate around.
Allows the byproducts of the combustion process to exit the combustion chamber when the correct valve/valves are open.
Physically closes and keeps the valves closed.
Four Stroke Cycle
Invented by Nikolaus Otto,1. intake, 2. compression. 3. power/combustion, 4. exhaust
The more an air/fuel mixture is compression the more combustion/power we get. It could be between 8.5:1 up to 13:1 in most gasoline 4 stroke internal combustion engines. It also has a direct effect on the Octane rating of gasoline that needs to be used in the engine.
Create a spark to ignite the compressed air/fuel mixture
Is bolted between the crankshaft and the transmission. It also has a ring gear around its outside edge that the starter engages to spin the engine on initial startup
Computer monitored and controlled system that is supplied with pressurized fuel by the fuel pump. It is capable of opening and closing when the injector is energized, an electromagnet moves a plunger that opens the valve and allows pressurized fuel to squirt out in a fine mist for a specified length of time called the pulse width.
An Emissions device that reduces unburned hydrocarbons and other pollutants in the exhaust
Throttlebody Fuel Injection
Oldest and simplest type that replaced carburetors with one or two fuel injectors located near the throttle body which is the throat of the engine's intake manifold.
Multi-point Fuel Injection
Devotes a separate injector nozzle to each cylinder right outside its intake port. port injection.. measures fuel more precisely than earlier styles, therefore improving the air-fuel ratio in each cylinder. This leads to improved power and fuel economy
Injects fuel directly into the combustion chamber bypassing the valves. Typically used in diesel engines however, it is becoming more common on gasoline engines in recent years.
Engine Control Unit (ECU)
Powertrain Control Module (PCM)
On computer controlled engines, a computer needs to monitor and send signals to a wide variety of electrical components. Sensor to be monitored include: mass airflow sensor (MAF), oxygen sensor (o2), throttle position sensor (TPS), coolant temperature sensor (ECT), cam or crankshaft position sensor, etc.
Provides a film of oil between the moving parts in an engine. Reservoir of oil in stored in the crank- case. An oil pump forces it from the crank-case up to the bearings and other critical moving parts in the engine. Without it, metal to metal contact happens and engine wear would occur.
Starting the Engine
An electric motor called the starter spins the engine's flywheel. This creates the initial 4 stroke cycle needed to get the engine running by itself.
Refers to the correct synchronization of a crankshaft, camshaft, piston, valves, and the fuel and air delivery to create an ignition event.
Ignition system composed of a distributor, coil, cap, rotor, spark plug wires, and spark plugs. The firing of the correct spark plug is determined by correct ignition timing.
Ignition system composed of multiple coils, spark plugs, and possibly some plug wires/boots. The firing of the correct spark plug is typically determined by a signal sent from a computer
At sea level, this is the amount of weight being pushed down upon everything by the column of air above. It is generally stated as 14.7 pounds per square inch (psi)
An engine whose cylinders are arranged in a line
V - Engine
An engine whose cylinders are arranged in a "V" formation
An engine whose cylinders are arranged in a pancake/opposed position. Pistons move up and down 180 degrees apart
Traditionally a "Stoichiometric" mixture is described at 14.7:1. If the ratio moves towards 10:1, this is referred to as "rich" and if the mixture moves towards 16:1, this is referred to as "lean".
Provides a slightly compressible material to help seal between the cylinder head and the engine block
A measure of distance between Top Dead Center (TDC) and Bottom Dead Center (BDC).
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