internal combustion engines

introducing combustion engines

A combustion engine is a complex machine that burns fuel to produce thermal energy and then uses the energy to do work. In a car, the engine does the work of providing kinetic energy that turns the wheels. The combustion engine in a car is a type of engine called an internal combustion engine. (Another type of combustion engine is an external combustion engine.)

how energy from the engine turns the wheels

In a car, the piston in the engine is connected by the piston rod to the crankshaft. The crankshaft rotates when the piston moves up and down. The crankshaft, in turn, is connected to the driveshaft. When the crankshaft rotates, so does the driveshaft. The rotating driveshaft turns the wheels of the car.

how internal combustion engines work

An internal combustion engine burns fuel internally, or inside the engine. This type of engine is found not only in cars but in most other motor vehicles as well. The engine works in a series of steps, which keep repeating. You can follow the steps in the Figure 1.1. 1. A mixture of fuel and air is pulled-into a cylinder through a valve, which then closes. 2. A piston inside the cylinder moves upward, compressing the fuel-air mixture in the closed cylinder. The mixture is now under a lot of pressure and very warm. 3. A spark from a spark plug ignites the fuel-air mixture, causing it to burn explosively within the confined space of the closed cylinder. 4. The pressure of the hot gases from combustion pushes the piston downward. 5. The piston moves up again, pushing exhaust gases out of the cylinder through another valve. 6. The piston moves downward again, and the cycle repeats. Q: The internal combustion engine converts thermal energy to another form of energy. Which form of energy is it? A: The engine converts thermal energy to kinetic energy, or the energy of a moving objectin this case, the moving piston.


how many cylinders

Most cars have at least four cylinders connected to the crankshaft. Their pistons move up and down in sequence, one after the other. A powerful car may have eight pistons, and some race cars may have even more. The more cylinders a car engine has, the more powerful its engine can be.

instructional diagrams

No diagram descriptions associated with this lesson


all combustion engines

a) burn fuel to produce thermal energy.

b) change thermal energy to kinetic energy.

c) burn fuel inside the engine.

-->  d) two of the above

in an internal combustion engine, fuel is burned in the

-->  a) cylinders.

b) valves.

c) spark plugs.

d) pistons.

a car engine provides the kinetic energy needed to

-->  a) turn the wheels.

b) apply the brakes.

c) power the lights.

d) two of the above

all cars have at least eight cylinders.

a. true

-->  b. false

the more pistons a car has, the greater the cars power is.

-->  a. true

b. false

diagram questions

No diagram questions associated with this lesson