This document summarizes information about valve mechanisms in internal combustion engines. It discusses the basic operation of valves using camshafts and the components involved like cam lobes, followers, push rods and rocker arms. It also introduces future camless valve technologies that would be electrically controlled. The document outlines the main types of valves used in 2-stroke and 4-stroke engines and lists the advantages of more advanced valve mechanisms as better fuel efficiency and performance, though they are more complex and expensive.

1. Excel polytechnic college
DEPARTMENT OF MECHANICAL
ENGINEERING

2. SEMINAR
THERMAL & AUTOMOBILE

3. Title : VALVE MECHANISM
Subject : THERMAL & AUTOMOBILE
Section : C
Department: Mechanical
Submitted by
KEERTHIVASAN

4. CONTENTS
• INTRODUCTON
• OPERATION
• TYPES
• VALVE MECHANISM IN CONVENTIONAL TYPE
• SOLIENOID OPERATED VALVES
• ADVANTAGES
• DISADVANTAGES

5. INTRODUCTION
• The valves are used to release the sucked
fuels , compressed gas or fuels , produced
power , exhaust the un burnt fuel and for
many purposes this is the introduction
about valves.

6. OPERATION
• Consists of a central cam shaft
• When cam shaft rotates the lobes push
against the valves to open them
• The cam is driven by taking input from
the crank shaft.
• A single cam shaft can be used to open
both the (i.e. intake and exhaust ) valves
(SOHC) or two cams can be used one for
intake and one for exhaust (DOHC).
 How the valves are opened and closed?

7. OPERATION
• Depending on RPM and engine load the
ECM would directly control all valve
timings.
• There will be no cam ( Camless Valves)
• Valve timing would be infinitely
controllable
• Valve timing will be controlled electrically
by Electronic Control Module (ECM)
• It is a future technology and currently not
in production.
Solenoid Operated Valves

8. TYPES OF VALVES
• COMPRESSION VALVE
• POWER VALVE
• SUCTION VALVE
• EXHAUST VALVE
FOR 2 STROKE ENGINES
FOR 4 STROKE ENGINES

9. • CAM SHAFT
• CAM FOLLOWER
• PUSH ROD
• ROCKER ARM
• VALVE SPRING
• VALVE GUIDE
• VALVE STEM
VALVE MECHANISM IN CONVENTIONAL
ENGINE

10. Advantages
• Better fuel efficiency
• High initial torque
• Lover emission
• Better performance

11. Disadvantages
• Higher cost of engine
• More complex mechanisms
• Lower overall engine life because of
increased wear.

12. CONCLUSION
• Even though some disadvantages
are present, we can expect electro-
hydraulic & electromechanical
valves to replace the conventional
camshaft technology.