New Trends in Internal Combustion Engines

CHIRAG KALADIYIL

Introduction• The internal combustion engine has been with

us since about 1885. • An internal combustion engine (ICE) is a heat

engine where the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit.

• An IC engine is fed with fossil fuels like natural gas or petroleum products such as gasoline, diesel fuel or fuel oil.

Will the IC engine be able to cope with these challenges also in the future?

1. Fuel Economy

2. Safety

3. Exhaust emission

4. Noise and vibration

New Trends in IC Engine

1. Cylinder Deactivation

2. Direct Injection

3. Variable valve timing and lift

4. Turbochargers

Cylinder Deactivation

• Cylinder deactivation is one of the technologies that improve fuel economy, the

objective of which is to reduce engine pumping losses under certain vehicle

operating conditions

• Cylinder Deactivation is the method of deactivating Cylinders as per the Power

requirement of the Engine in order to achieve better Fuel efficiency as well as

Emission Control.

• Cylinder deactivation works because only a small fraction of an engine’s peak

horsepower is needed to maintain cruising speed.

Working Of Cylinder Deactivation

Advantages• Lean combustion: Lean combustion returns 15 percent increase in fuel

efficiency over a conventional spark ignition engine.• Cleaner combustion: Cleaner combustion and lower emissions (especially

NOx) than a conventional spark ignition engine.• Compatibility: Compatible with gasoline as well as E85 (ethanol) fuel.• Easy fuel burning: Fuel is burned quicker and at lower temperatures,

reducing heat energy loss compared to a conventional spark engine.• Throttle less induction: Throttle less induction system eliminates

frictional pumping losses incurred in traditional (throttle body) spark engines.

Disadvantages• Engine balancing- Deactivating cylinders can cause change in engine balancing

which can lead to very violent vibration and increased noise levels. • Increased cost of manufacturing- the cost of the additional parts like electronic

control module and the complexity in the design and lifter pin mechanism will increase the cost of manufacturing

• Overall increase in weight- Due to the presence of additional components like hydraulic lines used in hydraulic sub system, lifter locking mechanism, and solenoid valves etc.

• Complexity of system makes maintenance difficult. - Complex lifter locking mechanism and solenoid valves are difficult to maintain.

Direct fuel Injection

Direct injection is where fuel is injected (directly) into the cylinders, not mixed with air in the inlet manifold or inlet ports before being drawn into the cylinders.

Types Of Direct Injection Systems

MPFi EngineMulti Point Fuel Injection system. In this system each cylinder has number of injectors to supply/spray fuel into the cylinders .

CRDi EngineCommon Rail Direct injection system. In this system, all the injectors are supplied by a common fuel supply line or a manifold called the common rail.

Advantages of Direct Fuel Injection

Due to multiple injections, uniform A/F mixture supplied to cylinder; thus difference in power developed in each cylinder is minimum. Noise and Vibration from the engine is less.

Since the engine is controlled by ECU, accurate A/F mixture supplied resulting in complete combustion leading to effective utilization of fuel supplied and hence low emission level.

Disadvantages of direct fuel injection

• The primary disadvantages of direct injection engines are complexity and cost.

• Direct injection systems are more expensive to build because their components must be more rugged -- they handle fuel at significantly higher pressures than indirect injection systems and the injectors themselves must be able to withstand the heat and pressure of combustion inside the cylinder.

Variable Valve Timing And Lift

• Principle is to use a two-position advance or retard of either an engine’s intake or exhaust camshaft to better match the engine’s operating conditions . Two main factors that determine an I.C engine performance are

• The point at which valves open.

• The duration of the valves being open.

Types of Variable Valve Timing System

VTEC Engine (Variable Valve-Timing and Lift Electronic Control) VTEC works by varying valve timing and lift to compensate for the time delay and out-of-phase arrival of the air-fuel charge at the intake valve. Shifts valve between two separate sets of cam lobes—one for high-speed operation and one for low.

Advantages

• Low fuel consumption appreciable increase in power

• Lower tail pipe emission.• Valvetronic system, optimize engine

power and efficiency.• Reduces pumping losses

Disadvantage

• Has a complex design to manufacture

• Is expensive

• High wear and tear occurs

• Very difficult to maintain

Turbocharger• A turbocharger is a turbine-driven forced induction device

that increases an internal combustion engine's efficiency and power output by forcing extra air into the combustion chamber.

• This improvement over a naturally aspirated engine's output results because the turbine can force more air, and proportionately more fuel, into the combustion chamber than atmospheric pressure alone.

• Turbochargers are commonly used on truck, car, train, aircraft, and construction equipment engines. They are most often used with Otto cycle and Diesel cycle internal combustion engines.

Working principle of a turbocharger• A turbocharger is a small radial fan pump

driven by the energy of the exhaust gases of an engine.

• A turbocharger consists of a turbine and a compressor on a shared shaft.

• The turbine converts exhaust to rotational force, which is in turn used to drive the compressor.

• The compressor draws in ambient air and pumps it in to the intake manifold at increased pressure, resulting in a greater mass of air entering the cylinders on each in take stroke.

Working of turbocharger

Advantages

• The more increase the pressure of the intake air above the local atmospheric pressure (boost), the more power the engine produces.

• Engines burn air and fuel at an ideal ratio of about 14.7:1, which means that if you bum more air, you must also bum more fuel.

• This is particularly useful at high altitudes: thinner air has less oxygen, reducing power by around 3% per 1,000 feet above sea level, but a turbocharger can compensate for that loss, pressurizing the intake charge to something close to sea level pressure.

Disadvantages

• Cost and complexity

• Detonation

• Large space requirement

• Turbo lag

Conclusion

• Internal combustion engines are among the most important engineering applications. The theory of application either depends on Diesel or Otto cycles. They are categorized either according to the operating cycle, or due to the mechanism of working. 

• Each type of engines has some advantages over the other one. Thus, the selection of the appropriate engine requires determining the conditions of application. 

• Despite the green hype, internal-combustion engines with its latest and advanced technology will keep powering vehicles for the foreseeable future