CYLINDER DEACTIVATION SYSTEM

BY V.GIRIDHARAN

B.E. Mechanical

INTRODUCTION

This topic focuses about the reduction of fuel

consumption of an internal combustion engine.

The power required is very less inside the city than the

peak power generated by the car.

This mechanism is introduced in 1981 by General

Motors .

It keeps on developing by adding new technologies by

car manufacturing companies.

MECHANISM

This is the method of deactivating engine cylinders according to requirement of power to achieve better fuel efficiency and also emission control.

It works because only a small fraction of an engine’s peak horsepower is needed to maintain cruising speed.

Each cylinder is disabled only at the intake and exhaust stroke. It takes 40 to 50 milliseconds.

Each cylinder is disabled by interrupting the operation of intake and exhausts valves with spark and fuel delivery.

METHODS FOR CYLINDER DEACTIVATION SYSTEM

Lifter Pin Control Mechanism

Variable Profile Cam Shaft

Active Valve Train Technology.

I. LIFTER PIN CONTROL MECHANISM

This mechanism consists of four subsystem:

Electronic Control Module Solenoid Valves Hydraulic Subsystem Lifter locking pin mechanism

PRINCIPLE OF OPERATION When the solenoid valve is energized, the

oil becomes pressurized in the control port, the pressure force acts on the pins and makes it lock.

It decouples the camshaft from the valves(i.e. inlet and outlet manifold). So the cylinder is deactivated.

BLOCK DIAGRAM OF LIFTER PIN CONTROL MECHANISM

A. ELECTRONIC CONTROL MODULE It measures the performance of

engine at all events to enable full time control.

It also calculates the total actuation time elapsed by all the systems.

B. SOLENOID VALVE OPERATION A 3-way normally closed direct

current ON\OFF solenoid valve. The common port of the valve is connected to an oil gallery.

The common port is switched to engine oil pressure for deactivation of cylinder(valve energized) .

WORKING OF SOLENOID VALVE

Figure shows the solenoid valve placement for deactivation cylinders 1,4,6,7 in a V8 engine.

C. HYDRAULIC SUBSYSTEM

The working fluid (engine oil) is to lock the lifter pin by pressure and it must be calculated.

The actuation time elapsed by the fluid must be taken into account, because the time taken to deactivate the cylinder is very less.

D. LOCKING PIN MECHANISM

Figure shows the locking pin mechanism

The common port of the control valve is connected via an oil gallery to a pair of spring based locking pins inside the valve lifter.

When the pins are locked the camshaft is decoupled from the engine valve. So that we deactivate the cylinder.

It is desirable to change the switching sequence of cylinder-by-cylinder and to complete transition from V8 to V4.

METHODS USED IN LIFTER PIN CONTROL MECHANISM1. Cylinder Bank Control. In this method the 2 cylinders from each bank is selected for deactivation. This control method is mainly used in inline cylinder engines 2. Individual Cylinder Control. In this method each cylinder is deactivated independently and its selection depends on firing order.

This control method is mainly used in Boxer engines and V engines.

II. VARIABLE PROFILE CAMSHAFT MECHANISM

This system allows the engine to have multiple cam shafts.

As the engine moves into different r.p.m computer can activate alternate lobes on the camshaft and change the cam timings.

This system uses a Cam Profile Switching tappet, to switch between two different cam profiles. In this way the engine gets best features of low speed as well as high speed camshaft of same engine.

This is similar to the patented V-Tech technology used in Honda.

III. ACTIVE VALVE TRAIN TECHNOLOGY

This system uses electrohydraulic operation, movement of engine poppet valves initiated by oil flow into and out of the hydraulic chamber.

It is controlled by fast acting electrohydraulic servo valves, this inturn allows variable timing, duration and lift

Increased combustion control due to variable lift and it offers fuel consumption benefits over conventional camshaft driven valve actuation mechanisms.

But this method is still in experimental stage to rectify the disadvantages.

Figure show the CAD Model of inlet and exhaust valve of a single cylinder

ADVANTAGES OF CYLINDER DEACTIVATED ENGINES

1. Increased fuel efficiency (10-25%).

2. Decreased emissions from deactivated cylinders.

3. Better breathing capability of the engine, thereby reducing the power consumed in suction stroke.

DISADVANTAGES1. Engine balancing – Deactivating cylinders can

cause change in engine balancing which leads to violent vibration and noises. The way of attaching counter masses to the moving parts like crankshaft is very difficult to calculate and attach the counter masses.

2. Increased cost of manufactuing – Though the deactivation process reduces operation costs, the additional parts like ECM and others will increase the cost of manufacturing.

3. Overall increase in weight

4. Complexity of system makes maintenance difficult.

5. Since these methods are still under experimental stage, the reliability of the engine is not predicted yet.

CONCLUSION To reduce the pollution from the

internal combustion engines and the demand of automobile which burns less fuel.

With the increase of price of petroleum products the fuel is burnt according to the power requirement.

So, Cylinder deactivation solve these problems to a great extend without compromising engine performance thus satisfies both manufacturer and consumer.

REFERENCES Research paper published by Quant Zheng,

Delphi Motors.

Internet.

Research paper published by Lotus and Eaton Automotive Systems.

THANK YOU