AUTOMOBILE ENGINES

V Engine

Inline Engine

W Engine

EngineWhat is an “Engine”?• An “Engine” is a device which converts one form of energy into

another form. But usually the word engine is associated with a device that converts Heat energy into mechanical work and are called as “Heat Engines”

Definition of “Heat Engine”• Heat engine is a device which transforms the chemical energy of

a fuel into thermal energy and utilizes this Mechanical energy into useful work.

• Heat engines can be classified into two broad types1. External Combustion Engines : The combustion takes place

outside the engines . The products of combustion transfer heat to a secondary fluid which is the working fluid of the cycle.

Example: Steam engines, where steam is the working fluid 2. Internal Combustion Engines : In Internal combustion

engines the products of combustion are directly the motive fluid.

Example: Petrol engines

Historical Development of Engines

Lenoir engine (1860) Free Piston Otto Langen Engine (1866)

Otto Engine based on Beau De Rochas Paper (1876)

Brayton engine Atkinson Engine 2 stroke Clerk’s Engine (1881)

Broad classification of heat engines

Heat Engines

IC Engines

Rotary Reciprocating

EC Engines

Reciprocating Rotary

Open cycle gas Turbine

Wankel Engine

Gasoline Engine

Diesel Engine

Steam Engine

Stirling Engine

Steam Engine

Closed cycle gas Turbine

Wankel Engine

Trebert Axial Engine

Advantages and Disadvantagesof Reciprocating IC engines

Advantages of Reciprocating IC Engines over other engines• Absence of heat exchangers, thus improved

efficiency• Work at an average temperature which is much

lower than the maximum temperature . Thus very high working fluid temperatures can be employed , resulting in higher efficiency.

• Can obtain higher thermal efficiency with moderate maximum working pressure, thus reducing the weight/power ratio.

Disadvantages of Reciprocating Engines• Vibration • Only certain fuels can be used and fuels used are

costly

Types of IC Engines

Cycle of Operation• Constant Volume Heat addition Engine or Otto Engine (also

called by the name Spark Ignition Engine/petrol engine)• Constant Pressure Heat addition Engine or Diesel Engine (also

called by the name Compression Ignition engine)Types of fuel Used• Engine using liquid fuels like Kerosene, petrol, Diesel,

Alcohol• Engines using gaseous fuels like CNG, LPG, Bio gas etc.• Engines using solid fuels like Charcoal powdered coal etc• Engines using two fuelsMethod of Charging• Naturally aspirated Engines• Supercharged EngineNumber of stroke• 2 stroke engines • 4 stroke engines

Engine design Consideration

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Load Factor• The first step in designing a new engine is to choose

the desired rated power output and rated speed. The load factor must be considered in choosing the speed. �

Wankel Engine

• Designed by German engineer Felix Wankel in 1954• Extremely lightweight and small when compared to

engines with similar power output.• Works on the same principle as the 4 stroke engine . In

Wankel engine the term Phase is used to describe a stroke to avoid confusion.

• Wankel Engine has 2 moving parts. One rotor and one eccentric Shaft.

• Internal and external timing gears are provided on the rotor and the eccentric shaft and are designed to maintain a constant phase relation between the two.

• Each phase takes place after 90° movement of the rotor. Usually eccentric shaft rotates at 3times the speed of rotor and thus for every 270 ° movement phase changes

Cycle of Operation of Wankel Engine

Cylinder vs. Rotary Engines

Reciprocating Cylinders• Uses pistons to regulate intake and

exhaust of fuel and gas.• All four strokes, intake compression,

combustion and exhaust occur in same cylinder.

• Pistons continually reverse direction• Lower rev limit

Rotary Wankel Engine• Has a spinning rotor that creates three

separate chambers and regulates the inflow and outflow of gasses.

• Each chamber draws in air and fuel, is compressed, ignited and combusted then expelled creating power while at the same time forcing the other two chambers to do the same.

• Rotors move in a continuous direction making it smoother

Advantages over reciprocating engine• The piston in a four stroke-cycle reciprocating engine

must momentarily come to rest four times per cycle as its direction of motion changes. In contrast, the moving parts in a rotary engine are in continuous unidirectional motion.

• Higher operating speeds. Thus twice as much power output as a reciprocating engine of same weight.

• Ease of balancing, and absence of vibration

Disdvantages over reciprocating engine• Sealing, leaks from the apex seals greatly reduces

efficiency of the engine.• High Operating Temperature, the housing operates at

steady state with constant heating in each chamber.• Low fuel efficiency and shorter engine life due to

damaged seals.

Geometryof Wankel Engine

• The housing inner surface has a mathematical form known as a Trochoid or Epitrochoid

• The ratio of radius of fixed rotor to radius of rotating rotor is 2:3

• The centre of the rotating rotor follows a circle . The distance between the centre of fixed rotor and the centre of rotating rotor is called Eccentricity.

• The ratio of the radius of the rotor divided by the eccentricity of the engine is called K factor

• K factor for a Wankel engine is usually maintained between 6-10

Engine Block•Foundation of the engine and contains pistons, crank shaft, cylinders, timing sprockets and sometimes the cam shaft.•The cylinder head is mounted on cylinder block .Water jackets or air fins are provide on the engine block for cooling.•Material-Cast Iron / Aluminium (Grade 319 (7% Si, 1% Fe, 3.5% Cu, 0.5% Mn, 0.35% Ni, 1% Zn, 0.25% Ti)•Manufactured by Casting

Components of an reciprocating Engine

Components of an reciprocating Engine

Piston

•Cylindrical component fitted into the cylinder forming the moving boundary of combustion system•With the help of lubricant and piston rings it provides a gas tight space between cylinder•Through connecting rod, forcesthe crank shaft to rotate.•Materials-Cast Iron/Aluminium alloy (hypereutectic alloys)•Manufactured by casting/ forging

Piston Rings

•Piston rings are fitted into the slots around the piston. They provide tight seal between piston and cylinder, thus preventing leakage and gases•Four stroke: Three rings Top two are compression rings (sealing the compression pressure in the cylinder) and the third is an oil ring (scrapes excessive oil from the cylinder walls) •Two Stroke: Two Rings Both the rings are Compression rings•Material- Cast Iron•Manufactured by Forging

Components of an reciprocating Engine

Crank Shaft•Converts reciprocating motion of piston •into rotary motion of the output shaft•Crankshaft of single cylinder engine contains a pair of crank arms and balancing weights, which are provided for static and dynamic balancing of the system•Materials- Alloy steels/ Cast Iron (alloying elements are manganese ,chromium, Molybdenum, Nickel, Cobalt, Vanadium•Manufacturing Method- Forging

Components of an reciprocating Engine

Connecting Rod

•Interconnects the piston and the crankshaft and transmits the gas forces from piston to crankshaft•Two ends of Connecting rod are called small end and big end•Small end is connected to Piston by Gudgeon Pin•Big end is connected to crankshaft by Crank Pin•Material- Alloy Steel (42CrMo4, 43CrMo4, 44csr4, C-70, EN-8D, SAE1141)•Manufactured by Forging

Components of an reciprocating Engine

Flywheel

•Attached to the crankshaft•The net torque applied on the crankshaft during one complete cycle of operation of the engine fluctuates . In order to achieve a uniform torque, flywheel is used•Transfers power from engine to Drive train•Material- Cast Iron•Manufactured by- Forging

Components of an reciprocating Engine

Hybrid Vehicles• Hybrid vehicles are the vehicles, which run on at-

least one alternate source of energy and gasoline. Most of the time that other alternate source of energy for hybrid cars is electricity (rechargeable batteries) hence those are called electric hybrid cars. These new hybrid cars are innovative, efficient and affordableExample: TVS Luna, a moped is type of hybrid because it combines the power or a gasoline engine with the pedal power of its raider

• Hybrid electric vehicles (HEVs) are powered by two energy sources An energy conversion unit such as a combustion engine or fuel cell. And energy storage device such as batteries ,ultras capacitors, fly wheels. A gasoline, methanol, compressed natural gas, hydrogen, or other alternative fuels may power the energy conversion unit.

Advantages over Common IC engines•The nature of HEV configuration enables several important advantages over pure electric vehicles (EVs).• Because the HEV engine shares the workload with the electric motor, it can be constructed smaller. This reduction in size call for weight reductions, leading to greater fuel economy•HEV engines can be optimized to operate within a specific speed range characterized by better fuel economy and reduced emissions

Levels of Hybrid Vehicles• There are two types of hybrid vehicles.• In one type, the electric motor acts as a side-kick to

the gas engine, assisting it whenever surplus power is needed. The electric motor alone is incapable of independently operating the vehicle. Honda's Power Assist technology in its hybrids, Civic and Insight is an example. Such vehicles are termed as Mild Hybrids. In mild hybrids, the gasoline engine provides the main source of power, and the electric motor provides additional power whenever needed.

• The second type of hybrid can be termed as a Full Hybrid, where the gasoline engine and the electric motor can operate the vehicle separately. In this type, the electric motor can drive the vehicle at lower speeds. In need of more speed, the gasoline engine kicks in. Toyota Prius and the Ford Escape implement the same technology.

Honda Insight

Toyota Prius

Components of HVEngine• The hybrid car has a gasoline engine much like the

one you will find on most cars. However, the engine on a hybrid is smaller and uses advanced technologies to reduce emissions and increase efficiency

Hybrid battery • The batteries in a hybrid car are the energy storage

device for the electric motor. Unlike the gasoline in the fuel tank, which can only power the gasoline engine, the electric motor on a hybrid car can put energy into the batteries as well as draw energy from them.

• The batteries perform 2 functions: they send energy to the electric motor and store energy that is being captured by the generator.

Honda Insight IMA

Toyota 1NZ-FXE engine (left) with early HS

The electric drive, a powerful 96 kW (131 hp) motor, is located on the front axle. In contrast, the rear axle is driven by a powerful BMW Twin Power Turbo 1.5-litre 3-cylinder petrol engine with 170 kW (231 hp) of peak performance and up to 320 Nm of torque; . These two drive systems combine to accelerate the BMW i8 from 0 to 100 km/h in 4.4 seconds – with fuel consumption of just 2.1 l per 100 km CO2 emissions of 49 g/km

Types of Hybrid CarsParallel hybrid car• Parallel hybrid systems, which are most commonly produced at present, have both

an internal combustion engine (ICE) and an electric motor connected to a mechanical transmission.

• Most designs combine a large electrical generator and a motor into one unit, often located between the combustion engine and the transmission, replacing both the conventional starter motor and the alternator. To store power, a hybrid uses a large battery pack with a higher voltage than the normal automotive 12 volts.

•Honda's Insight, Civic, and Accord hybrids are examples of production parallel hybrids

Types of Hybrid Cars• Series hybrid car• In a series-hybrid system, the combustion engine drives an electric generator

instead of directly driving the wheels. The generator provides power for the driving electric motors. In short, a series-hybrid is simple, the vehicle is driven by electric motors with a generator set providing the electric power.

Types of Hybrid CarsSeries Parallel hybrid car• They incorporate power-split devices allowing for power paths from the engine to the wheels that can

be either mechanical or electrical. The main principle behind this system is the decoupling of the power supplied by the engine (or other primary source) from the power demanded by the driver.

• A combustion engine's torque output is minimal at lower RPMs and, in a conventional vehicle, a larger engine is necessary for acceptable acceleration from standstill. The larger engine, however, has more power than needed for steady speed cruising. An electric motor, on the other hand, exhibits maximum torque at standstill and is well-suited to complement the engine's torque deficiency at low RPMs. In a power-split hybrid, a smaller, less flexible, and highly efficient engine can be used.

Porshe 918 Spyder, 0-100 in 2.2s

La Ferrari, 0-100 in 2.4s

Fuel Cell Vehicles• A fuel cell vehicle (FCV) or fuel cell electric vehicle (FCEV)

is a type of vehicle which uses a fuel cell to power its on-board electric motor. Fuel cells in vehicles create electricity to power an electric motor, generally using oxygen from the air and compressed hydrogen. A fuel cell vehicle that is fueled with hydrogen emits only water and heat, but no tailpipe pollutants, therefore it is considered a zero-emissions vehicle.

• Fuel cells are like batteries but instead of the chemicals being inside the battery, we get the chemicals from outside. We feed hydrogen gas into one side. Then an electrochemical reaction occurs on the electrode to split the hydrogen into hydrogen ions and electrons. Only the hydrogen ions can transfer through the cell through the electrolyte. The electrons can’t and have to go through a different path. At the other electrode, the hydrgoen ions and electrons combine with oxygen from the air and makes water, and nothing else like carbon dioxide. The alternative path of the electrons is an electric current..i.e. electricity.

Toyota Mirai

Honda FCX Clarity

How fuel Cells Work

Types of Fuel CellsMolten carbonate cellsSolid oxide cellsDirect methanol and other non-hydrogen cellsBiofuel cellsPhosphoric Acid Proton Exchange MembraneAcid and alkaline cells

Historical background • Electric cars were present in early 20th century,

when electricity was preferred in automobile propulsion.

• Advances in internal combustion technology, especially the electric starter, the greater range of gasoline cars, quicker refueling times, and growing petroleum infrastructure, along with the mass production of gasoline vehicles reduced prices of gasoline cars to less than half that of equivalent electric cars, which led to the decline of electric propulsion.

• The energy crisis of 1970s and 1980s brought a renewed interest in electric vehicles. Further the global economic recession of late 2000s called to abandon the fuel inefficient SUVs, in favor of small cars, hybrid cars and electric cars.

Tribelhorn

Electric Vehicles • A battery electric vehicle (BEV) is a vehicle that is powered by electricity stored on the vehicle in a battery through the use of one or more electric motors

• An Electric car is powered by an Electric Motor rather than a Gasoline Engine.

• The Electric Motor gets its power from a controller. The Controller is powered from an array of rechargeable batteries

Tesla Roadster

Reva

Working• The heart of an electric car is the combination of the

electric motor ,The motor's controller, The batteries• The controller takes power from the batteries and delivers

it to the motor. The accelerator pedal hooks to a pair of potentiometers (variable resistors), and these potentiometers provide the signal that tells the controller how much power it is supposed to deliver. The controller can deliver zero power (when the car is stopped), full power (when the driver floors the accelerator pedal), or any power level in between.

• The signal from the potentiometers tells the controller how much power to deliver to the electric car's motor. There are two potentiometers for safety's sake. The controller reads both potentiometers and makes sure that their signals are equal. If they are not, then the controller does not operate. This arrangement guards against a situation where a potentiometer fails in the full-on position.

Pulse Width Modulation

Electric-car Motors and Batteries

Motors• Electric cars can use AC or DC motors:• If the motor is a DC motor, then it may run on anything

from 96 to 192 volts. Many of the DC motors used in electric cars come from the electric forklift industry.

• If it is an AC motor, then it probably is a three-phase AC motor running at 240 volts AC with a 300 volt battery pack.

Batteries• Electric vehicle batteries differ from starting, lighting,

and ignition (SLI) batteries because they are designed to give power over sustained periods of time. Deep cycle batteries are used instead of SLI batteries for these applications. Traction batteries must be designed with a high ampere-hour capacity. Batteries for electric vehicles are characterized by their relatively high power-to-weight ratio, energy to weight ratio and energy density

• Rechargeable batteries used in electric vehicles include lead-acid NiCd, nickel metal hydride, lithium ion, Li-ion polymer

The weak link in any electric car is the batteries. There are significant problems with current lead-acid battery technology:1. They are heavy (a typical lead-acid battery

pack weighs 1,000 pounds or more).2. They are slow to charge (typical recharge

times for a lead-acid pack range between four to 10 hours for full charge, depending on the battery technology and the charger).

3. They have a short life (three to four years, perhaps 200 full charge/discharge cycles).

4. They are expensive

Advantages and Disadvantages • Advantages of an Electric Car

1. No Gas Required2. Savings3. No Emissions4. Low Maintenance5. No Noise Pollution• Disadvantages of an Electric Car1. Short Driving Range and Speed2. Lack of recharge points3. Longer Recharge Time4. Silence as Disadvantage- Can lead to accidents5. Costly battery Replacement

Gas Turbine• A gas turbine, also called a combustion turbine, is a type of internal combustion engine. It

has an upstream rotating compressor coupled to a downstream turbine, and a combustion chamber in between.

Gas Turbine components• Inlet System Collects and directs air into the gas turbine. Often, an air cleaner and silencer

are part of the inlet system. It is designated for a minimum pressure drop while maximizing clean airflow into the gas turbine.

• Compressor Provides compression, and, thus, increases the air density for the combustion process. The higher the compression ratio, the higher the total gas turbine efficiency . Low compressor efficiencies result in high compressor discharge temperatures, therefore, lower gas turbine output power.

• Combustor Adds heat energy to the airflow. The output power of the gas turbine is directly proportional to the combustor firing temperature; i.e., the combustor is designed to increase the air temperature up to the material limits of the gas turbine while maintaining a reasonable pressure drop.

• Gas Producer Turbine Expands the air and absorbs just enough energy from the flow to drive the compressor. The higher the gas producer discharge temperature and pressure, the more energy is available to drive the power turbine, therefore, creating shaft work.

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Simplistic Gas Turbines working principles

1-2 Isentropic compression (in a compressor)2-3 Constant pressure heat addition (in a combustor)3-4 Isentropic expansion (in a turbine)4-1 Constant pressure heat rejection

Why gas turbines are not popular?

• Engine clogging problems• Very large in size compared to a normal

piston engine• Very costly to manufacture• Exhaust gas posses lot of energy and if not

cooled down might harm the vehicle behind you

• Very hard to control the speed of the engine• High noise pollution• Can be used to charge a battery, but highly

inefficient. (this

Howmet TX turbine sports car

MTT Turbine Superbike

Jaguar C-X75

F1 car enginesAir Intake• The engine air intake on Formula 1 car is

positioned behind and above the driver's head to capture high-pressure, relatively undisturbed air. Inside the air intake is an expansion chamber (diffuser) that slows the air down and thus increases its pressure ready for its passage into the engine inlet manifold.

• The air intake is positioned away from sources of heat, such as the track and radiators, to minimize the air temperature. The intake faces the direction of travel to take advantage of a small ram effect the car induces as it moves forward through the air.

Mercedes PU106-Type Hybrid

F1 car engines• F1 cars are usually associated with

Pneumatic operated Valves, where as the normal engines have Spring operated Valves. The pneumatic operated Valves can sustain the high RPM of the F1 car engines

• The F1 cars are fitted with turbo charges which utilizes the power of exhaust gases to generate electricity , which is stored in battery during deceleration.

• The F1 car engines operate at much higher RPM range compared to the normal vehicles