PRESENTATION ON CAMLESS ENGINE

Suchitra MishraRegd No.: 0801211137

B.Tech Mechanical Engineering

CAM IN A CONVENTIONAL IC ENGINE

The cam is used in the internal combustion engine to operate the valves

Cam is the device which converts rotary motion of camshaft to the linear motion of valves

The valve mechanism operations consist of cam, tappet, rocker arm, spring and valves

Valve train schematic

CAM IN A CONVENTIONAL IC ENGINE

DISADVANTAGES

Less volumetric efficiency , improper combustion and ultimately detonation in Spark Ignition (SI) engine

Reduction in output of the engine.

Valve timing diagram at slow speed and high speed are different, which reduces flexibility of engine.

Cam design need to compromise between maximum efficiency and power.

Types of camless engines

using Hydraulic actuators using Pneumatic actuators using Electromagnetic actuators using Solenoid control actuators using Electro-hydraulic (using

piezoelectric) actuators

Hydraulic Actuator

CASE I

When the spool valve translates up, fluid flows through the B port and pressurizes the upper cavity of the cylinder block. This pressurization results in the downward translation of the piston. In turn, the engine valve is being opened as the piston translates down.

Hydraulic Actuator Contd…

CASE II

The opposite occurs as the spool valve translates down. Port end pressurizes the lower cavity of the cylinder block, piston to rise and allows the engine valve to close.

Hydraulic Actuator Contd…

DISADVANTAGES

Hydraulic system would not be fast enough with it's inherent slowness due to the inertia of the fluid flow.

The support components would increase weight and consume more space.

Pneumatic actuators

Pneumatic actuators were chosen after running comparison tests among different methods. Pressurized air was chosen due to its low mass, allowing fast response and stability over a broad temperature range. The researchers found that hydraulic systems had sluggish response, especially at low temperatures. The pressurized air was controlled by EM valves. All flow path distances were minimized to increase the response time of the actuator by reducing the volume of air required for actuation. The pressurized air opened the engine valves based on the timed electrical signal input to the “Electromagnetic Latch”.

Pneumatic actuators Contd…

DISADVANTAGES

A pneumatic system would have to operate at extremely high pressures to help overcome the time delay in building up pressure to move the valve.

The support components (pumps & plumbing for pneumatic) would increase weight and consume more space.

Electromagnetic Actuators

The camshaft of the engine is replaced by electromagnetic actuators for opening and closing each valve independently. The principle of the actuators is based on an oscillating mass-spring system with two magnetic coils holding the valve alternatively opened and closed .The main components are: the actuators, the Valve Control Unit (VCU), the wiring rail and the Electronic Control Unit (ECU).

Electromagnetic Actuators Contd…

ADVANTAGES

Fuel consumption reduction (15-20%)

Emissions reduction

Drive ability improvement

Shorter torque response time during transients

Electromagnetic Actuators Contd…

DISADVANTAGES

The support components would increase weight and consume more space.

Piezoelectric Controlled Hydraulic Actuator

Solenoid Control Actuators

This is also known as electromagnetic coil valve actuation system (ECVAS)

The system consists of design of :

solenoid sensing wheel and driving electronic circuit

Solenoid Control Actuators Contd…

To summarize, circuit get its input from the sensing wheel on which phototransistors and LED are placed. Timing adjustable slots are designed on the sensing wheel, such that the rotation of this wheel gives required crank angles used for valve operations. This wheel is fixed in concurrence with cam wheel. The photo transistors will conduct as light of LED incident on them, thus it will provide a path to relay and hence the voltage is directly provided to electromagnetic valves for operation

Solenoid Control Actuators Contd…

ADVANTAGES

Better Fuel Efficiency Higher Output Performance of Engine Reduction of Emission

Solenoid Control Actuators Contd…

DISADVANTAGES

Power loss cannot be avoided .

If electric system fails, big problem could occur.

Are bulky and consume lot of space.

Large winding and heavy current draw.

USE OF THE CAMLESS ENGINE

These are huge 2 stroke Diesel engines with power rating more than 100,000 KW.

These engines are running with computer hardware ,controlling both fuel exhaust valve operation and the Cylinder Lubrication.

Camless Engines are made by MAN, B&W, Mitsubishi and New Sulzer.

DISCUSSION & CONCLUSION

DISCUSSION

Although the problem of the power loss, friction , torque & maximum power may be tackled using camless engines, there are also some problems which arises due to the use of the camless engines

The use of hydraulic actuators lead to the slowness due to the inertia of the fluid flow. The use of the pneumatic actuators lead to the use of the high air pressure system.

The use of electromagnetic, piezoelectric and solenoid control actuators need electrical power supply. Also the revised camless setup will increase space and weight and initial investment too

DISCUSSION & CONCLUSION

CONCLUSION

Hence it is being concluded that the use of camless engines lead to increase in fuel efficiency and reduced emission still the space , weight and other factors are to be dealt with so as to make the use of camless engine economical which is the primary concern of any customer.