Valve Mechanism

A valve mechanism is a group of components that
opens and closes the intake and exhaust valves in
the cylinder head at the appropriate timing.
Crankshaft
Timing sprocket
Timing chain
Intake camshaft
Intake valve
Exhaust camshaft
Exhaust valve
* The diagram shows a VVT-i system valve
mechanism.

Intake stroke

The exhaust valve closes and the intake valve
opens. The downward stroke of the piston causes
the air-fuel mixture to be drawn into the cylinder
from the open intake valve

Exhaust stroke

The exhaust valve opens as the piston is about to
complete its downward stroke. Then, the exhaust
gases that result from the combustion are
discharged outside of the cylinder

Combustion stroke

When the piston is about to complete its upward
stroke, current flows to the spark plug, thus
creating a spark. This is then followed by the
combustion of the compressed air-fuel mixture and
an explosion. This explosion pushes the piston
downward, causing the crankshaft to rotate

Compression stroke

The piston completes its downward stroke and the
intake valve closes. The air-fuel mixture that is
drawn into the cylinder becomes highly
compressed with the upward stroke of the piston

Fuel cell hybrid vehicle (FCHV)

This electric vehicle uses the electric energy that is
created when the hydrogen fuel reacts with the
oxygen in the air to form water. Because it emits
only water, this is considered to be the ultimate
form of low- pollution vehicle, and is anticipated to
become the motive power for the next generation.
• The diagram indicates Toyota fuel cell hybrid
system.
Power control unit
Electric motor
Fuel cell stack
Hydrogen storage system
Secondary battery

Electric vehicle (EV)

This vehicle uses the power of the batteries to
operate the electric motor. Instead of using fuel, the
batteries require recharging. It offers many
advantages, including zero emissions and low
noise during operation. System of wheel drive uses
290V, on the other hand, other electric 12V.
• The diagram indicates Toyota EV system.
Power control unit
Electric motor
Battery