39987653 fuel injection notes

8/6/2019 39987653 Fuel Injection Notes

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Fuel injection

Fuel injection is a system for mixing fuel with air in an internal combustion engine. Ithas become the primary fuel delivery system used inautomotivepetrol engines, having

almost completely replaced carburetors in the late 1980s.

A fuel injection system is designed and calibrated specifically for the type(s) of fuel it

will handle. Most fuel injection systems are for gasoline ordiesel applications. With theadvent of electronic fuel injection (EFI), the diesel and gasoline hardware has become

similar. EFI's programmable firmwarehas permitted common hardware to be used with

different fuels.

Carburetors were the predominant method used to meter fuel on gasoline engines beforethe widespread use of fuel injection. A variety of injection systems have existed since the

earliest usage of the internal combustion engine.

The primary difference between carburetors and fuel injection is that fuel injection

atomizes the fuel by forcibly pumping it through a small nozzle under high pressure,while a carburetor relies on low pressure created by intake air rushing through it to add

the fuel to the airstream.

Objectives

The functional objectives for fuel injection systems can vary. All share the central task of

supplying fuel to the combustion process, but it is a design decision how a particular

system will be optimized. There are several competing objectives such as:

power output

fuel efficiency

emissions performance

ability to accommodatealternative fuels

reliability driveability and smooth operation

initial cost

maintenance cost

diagnostic capability

range of environmental operation

Certain combinations of these goals are conflicting, and it is impractical for a single

engine control system to fully optimize all criteria simultaneously. In practice,automotive engineers strive to best satisfy a customer's needs competitively. The modern

digital electronic fuel injection system is far more capable at optimizing these competing

objectives consistently than a carburetor. Carburetors have the potential to atomize fuelbetter (see Pogue and Allen Caggiano patents).
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Benefits

[edit] Engine operation

Operational benefits to the driver of a fuel-injected car include smoother and moredependable engine response during quickthrottletransitions, easier and more dependable

engine starting, better operation at extremely high or low ambient temperatures, increased

maintenance intervals, and increased fuel efficiency. On a more basic level, fuel injectiondoes away with the choke which on carburetor-equipped vehicles must be operated when

starting the engine from cold and then adjusted as the engine warms up.

An engine's air/fuel ratio must beprecisely controlled under all operating conditions to

achieve the desired engine performance, emissions, driveability, and fuel economy.Modern electronic fuel-injection systems meter fuel very accurately, and use closed loop

fuel-injection quantity-control based on a variety of feedback signals from an oxygen

sensor, a mass airflow (MAF) ormanifold absolute pressure (MAP) sensor, a throttleposition (TPS), and at least one sensor on the crankshaft and/or camshaft(s) to monitor

the engine's rotational position. Fuel injection systems can react rapidly to changing

inputs such as sudden throttle movements, and control the amount of fuel injected tomatch the engine's dynamic needs across a wide range of operating conditions such as

engine load, ambient air temperature, engine temperature, fuel octane level, and

atmospheric pressure.

A multipoint fuel injection system generally delivers a more accurate and equal mass offuel to each cylinder than can a carburetor, thus improving the cylinder-to-cylinder

distribution. Exhaust emissions are cleaner because the more precise and accurate fuel

metering reduces the concentration of toxic combustion byproducts leaving the engine,and because exhaust cleanup devices such as the catalytic convertercan be optimized to

operate more efficiently since the exhaust is of consistent and predictable composition.

Fuel injection generally increases engine fuel efficiency. With the improved cylinder-to-

cylinder fuel distribution, less fuel is needed for the same power output. When cylinder-to-cylinder distribution is less than ideal, as is always the case to some degree with a

carburetor or throttle body fuel injection, some cylinders receive excess fuel as a side

effect of ensuring that all cylinders receivesufficientfuel. Power output is asymmetricalwith respect to air/fuel ratio; burning extra fuel in the rich cylinders does not reduce

power nearly as quickly as burning too little fuel in the lean cylinders. However, rich-

running cylinders are undesirable from the standpoint of exhaust emissions, fuelefficiency, engine wear, and engine oil contamination. Deviations from perfect air/fueldistribution, however subtle, affect the emissions, by not letting the combustion events be

at the chemically ideal (stoichiometric) air/fuel ratio. Grosser distribution problems

eventually begin to reduce efficiency, and the grossest distribution issues finally affectpower. Increasingly poorer air/fuel distribution affects emissions, efficiency, and power,

in that order. By optimizing the homogeneity of cylinder-to-cylinder mixture distribution,
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all the cylinders approach their maximum power potential and the engine's overall power

output improves.

A fuel-injected engine often produces more power than an equivalent carbureted engine.Fuel injection alone does not necessarily increase an engine's maximum potential output.

Increased airflow is needed to burn more fuel, which in turn releases more energy andproduces more power. The combustion process converts the fuel's chemical energy into

heat energy, whether the fuel is supplied by fuel injectors or a carburetor. However,airflow is often improved with fuel injection, the components of which allow more design

freedom to improve the air's path into the engine. In contrast, a carburetor's mounting

options are limited because it is larger, it must be carefully oriented with respect togravity, and it must be equidistant from each of the engine's cylinders to the maximum

practicable degree. These design constraints generally compromise airflow into the

engine. Furthermore, a carburetor relies on a restrictive venturi to create a local airpressure difference, which forces the fuel into the air stream. The flow loss caused by the

venturi, however, is small compared to other flow losses in the induction system. In a

well-designed carburetor induction system, the venturi is not a significant airflowrestriction.

Fuel is saved while the car is coasting because the car's movement is helping to keep the

engine rotating, so less fuel is used for this purpose. Control units on modern cars react to

this and reduce or stop fuel flow to the engine reducing wear on the brakes.[citation needed]

Basic function

The process of determining the necessary amount of fuel, and its delivery into the engine,are known as fuel metering. Early injection systems used mechanical methods to meter

fuel (non electronic, or mechanical fuel injection). Modern systems are nearly all

electronic, and use an electronic solenoid (the injector) to inject the fuel. An electronic

engine control unit calculates the mass of fuel to inject.

Modern fuel injection schemes follow much the same setup. There is a mass airflow

sensor or manifold absolute pressure sensor at the intake, typically mounted either in the

air tube feeding from the air filter box to the throttle body, or mounted directly to the

throttle body itself. The mass airflow sensor does exactly what its name implies; it sensesthe mass of the air that flows past it, giving the computer an accurate idea of how much

air is entering the engine. The next component in line is the Throttle Body. The throttle

body has a throttle position sensor mounted onto it, typically on the butterfly valve of thethrottle body. The throttle position sensor (TPS) reports to the computer the position of

the throttle butterfly valve, which the ECM uses to calculate the load upon the engine.

The fuel system consists of a fuel pump (typically mounted in-tank), a fuel pressureregulator, fuel lines (composed of either high strength plastic, metal, or reinforced
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rubber), a fuel rail that the injectors connect to, and the fuel injector(s). There is a coolant

temperature sensor that reports the engine temperature to the ECM, which the engine uses

to calculate the proper fuel ratio required. In sequential fuel injection systems there is acamshaft position sensor, which the ECM uses to determine which fuel injector to fire.

The last component is the oxygen sensor. After the vehicle has warmed up, it uses the

signal from the oxygen sensor to perform fine tuning of the fuel trim.

The fuel injector acts as the fuel-dispensing nozzle. It injects liquid fuel directly into theengine's air stream. In almost all cases this requires an external pump. The pump and

injector are only two of several components in a complete fuel injection system.

In contrast to an EFI system, a carburetor directs the induction air through a venturi,

which generates a minute difference in air pressure. The minute air pressure differencesboth emulsify (premix fuel with air) the fuel, and then acts as the force to push the

mixture from the carburetor nozzle into the induction air stream. As more air enters the

engine, a greater pressure difference is generated, and more fuel is metered into the

engine. A carburetor is a self-contained fuel metering system, and is cost competitivewhen compared to a complete EFI system.

An EFI system requires several peripheral components in addition to the injector(s), in

order to duplicate all the functions of a carburetor. A point worth noting during times offuel metering repair is that early EFI systems are prone to diagnostic ambiguity. A single

carburetor replacement can accomplish what might require numerous repair attempts to

identify which one of the several EFI system components is malfunctioning. Newer EFIsystems since the advent ofOBD II diagnostic systems, can be very easy to diagnose due

to the increased ability to monitor the realtime data streams from the individual sensors.

This gives the diagnosing technician realtime feedback as to the cause of the drivability

concern, and can dramatically shorten the number of diagnostic steps required toascertain the cause of failure, something which isn't as simple to do with a carburetor. On

the other hand, EFI systems require little regular maintenance; a carburetor typically

requires seasonal and/or altitude adjustments.

Typical EFI components

Injectors

Fuel Pump

Fuel Pressure Regulator

ECM - Engine Control Module; includes a digital computer and circuitry to

communicate with sensors and control outputs.

Wiring Harness

Various Sensors (Some of the sensors required are listed here.)

Crank/Cam Position: Hall effect sensor

Airflow: MAF sensor, sometimes this is inferred with a MAPsensor
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Exhaust Gas Oxygen: Oxygen sensor,EGO sensor, UEGO sensor

Functional description

Central to an EFI system is a computer called the Engine Control Unit(ECU), whichmonitors engine operating parameters via varioussensors. The ECU interprets these

parameters in order to calculate the appropriate amount of fuel to be injected, among

other tasks, and controls engine operation by manipulating fuel and/or air flow as well asother variables. The optimum amount of injected fuel depends on conditions such as

engine and ambient temperatures, engine speed and workload, and exhaust gas

composition.

The electronic fuel injector is normally closed, and opens to inject pressurized fuel aslong as electricity is applied to the injector's solenoid coil. The duration of this operation,

called thepulse width, is proportional to the amount of fuel desired. The electric pulse

may be applied in closely-controlled sequence with the valve events on each individualcylinder (in a sequential fuel injection system), or in groups of less than the total number

of injectors (in a batch fire system).

Since the nature of fuel injection dispenses fuel in discrete amounts, and since the nature

of the 4-stroke-cycle engine has discrete induction (air-intake) events, the ECU calculatesfuel in discrete amounts. In a sequential system, the injected fuel mass is tailored for each

individual induction event. Every induction event, of every cylinder, of the entire engine,

is a separate fuel mass calculation, and each injector receives a unique pulse width based

on that cylinder's fuel requirements.

It is necessary to know the mass of air the engine "breathes" during each induction event.This is proportional to the intake manifold's air pressure/temperature, which is

proportional to throttle position. The amount of air inducted in each intake event isknown as "air-charge", and this can be determined using several methods. (See MAF

sensor, and MAP sensor.)

The three elemental ingredients for combustion are fuel, air and ignition. However,

complete combustion can only occur if the air and fuel is present in the exactstoichiometric ratio, which allows all the carbon and hydrogen from the fuel to combine

with all the oxygen in the air, with no undesirable polluting leftovers. Oxygen sensors

monitor the amount of oxygen in the exhaust, and the ECU uses this information to adjust

the air-to-fuel ratio in real-time.

To achieve stoichiometry, the air mass flow into the engine is measured and multiplied

by the stoichiometric air/fuel ratio 14.64:1 (by weight) for gasoline. The required fuel

mass that must be injected into the engine is then translated to the required pulse widthfor the fuel injector. The stoichiometric ratio changes as a function of the fuel; diesel,

gasoline, ethanol, methanol, propane, methane (natural gas), or hydrogen.
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Deviations from stoichiometry are required during non-standard operating conditions

such as heavy load, or cold operation, in which case, the mixture ratio can range from

10:1 to 18:1 (for gasoline). In early fuel injection systems this was accomplished with athermotime switch.

Pulse width is inversely related to pressure difference across the injector inlet and outlet.For example, if the fuel line pressure increases (injector inlet), or the manifold pressure

decreases (injector outlet), a smaller pulse width will admit the same fuel. Fuel injectorsare available in various sizes and spray characteristics as well. Compensation for these

and many other factors are programmed into the ECU's software.

Multi-point fuel injection

Multi-point fuel injection injects fuel into the intake port just upstream of the cylinder's

intake valve, rather than at a central point within an intake manifold. MPFI (or just MPI)

systems can be sequential, in which injection is timed to coincide with each cylinder'sintake stroke, batched, in which fuel is injected to the cylinders in groups, without

precise synchronization to any particular cylinder's intake stroke, orSimultaneous, in

which fuel is injected at the same time to all the cylinders.

Many modern EFI systems utilize sequential MPFI; however, it is beginning to bereplaced by direct injection systems in newer gasoline engines.

Mpfi stands for 'multi point (electronic) fuel injection'. This system injects fuel intoindividual cylinders, based on commands from the on board engine management

system computer popularly known as the Engine Control Unit/ECU.

Mpfi Systems can either be : a) Sequential i.e direct injection into individualcylinders against their suction strokes, or b) Simultaneous i.e together

for all the four or whatever the number of cylinders, or c) Group i.e into Cylinder-

Pairs.

These techniques result not only in better power balance amongst the cylinders but

also in higher output from each one of them, along with faster throttle response.

Of these variants of Mpfi, 'Sequential' is the best from the above considerations of

power balance/output.

Sefi, as advertised by Ford Ikon, stands for 'Sequential Electronic Fuel Injection',which technically is the best of the above variants of Mpfi. Hyundai/Maruti Mpfisystems are in fact Sefi too. Daewoo India had the (b) or (c) variants of above Mpfi

systems on its Cielo/Matiz.

On the other hand, older Opel-Astras had a 'single point' fuel injection system,which is in between an Mpfi and the now obsolete Single-Carburettor systems.
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Common rail fuel injector

On diesel engines, it features a high-pressure (over 1,000bar/15,000psi) fuel railfeeding

individual solenoid valves, as opposed to low-pressure fuel pumpfeeding unit injectors(Pumpe Dse or pump nozzles). Third-generation common rail diesels now feature

piezoelectricinjectors for increased precision, with fuel pressures up to

1,800bar/26,000psi.

[edit] Principles

Solenoid orpiezoelectric valves make possible fineelectronic control over the fuelinjection time and quantity, and the higher pressure that the common rail technology

makes available provides better fuel atomisation. In order to lower engine noise the

engine's electronic control unit can inject a small amount of diesel just before the maininjection event ("pilot" injection), thus reducing its explosiveness and vibration, as well

as optimising injection timing and quantity for variations in fuel quality, cold starting,

and so on. Some advanced common rail fuel systems perform as many as five injectionsper stroke.[7]
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Common rail engines require no heating up time[citation needed] and produce lower engine

noise and emissions than older systems.

Diesel engines have historically used various forms of fuel injection. Two common typesinclude the unit injection system and the distributor/inline pump systems (See diesel

engine andunit injectorfor more information). While these older systems providedaccurate fuel quantity and injection timing control they were limited by several factors:

They were cam driven and injection pressure was proportional to engine speed.This typically meant that the highest injection pressure could only be achieved at

the highest engine speed and the maximum achievable injection pressure

decreased as engine speed decreased. This relationship is true with all pumps,

even those used on common rail systems; with the unit or distributor systems,however, the injection pressure is tied to the instantaneous pressure of a single

pumping event with no accumulator and thus the relationship is more prominent

and troublesome.

They were limited on the number of and timing of injection events that could becommanded during a single combustion event. While multiple injection events are

possible with these older systems, it is much more difficult and costly to achieve.

For the typical distributor/inline system the start of injection occurred at a pre-

determined pressure (often referred to as: pop pressure) and ended at a pre-

determined pressure. This characteristic results from "dummy" injectors in thecylinder head which opened and closed at pressures determined by the spring

preload applied to the plunger in the injector. Once the pressure in the injector

reached a pre-determined level, the plunger would lift and injection would start.

In common rail systems a high pressure pump stores a reservoir of fuel at high pressure

up to and above 2,000 bars (29,000 psi). The term "common rail" refers to the fact thatall of the fuel injectors are supplied by a common fuel rail which is nothing more than a

pressure accumulator where the fuel is stored at high pressure. This accumulator supplies

multiple fuel injectors with high pressure fuel. This simplifies the purpose of the highpressure pump in that it only has to maintain a commanded pressure at a target (either

mechanically or electronically controlled). Thefuel injectors are typically ECU-

controlled. When the fuel injectors are electrically activated a hydraulic valve (consistingof a nozzle and plunger) is mechanically or hydraulically opened and fuel is sprayed into

the cylinders at the desired pressure. Since the fuel pressure energy is stored remotely and

the injectors are electrically actuated the injection pressure at the start and end ofinjection is very near the pressure in the accumulator (rail), thus producing a square

injection rate. If the accumulator, pump, and plumbing are sized properly, the injection

pressure and rate will be the same for each of the multiple injection events.
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Emission standard

Emissions standards are requirements that set specific limits to the amount ofpollutantsthat can be released into the environment. Many emissions standards focus on regulating

pollutants released by automobiles(motor cars) and other poweredvehicles but they canalso regulate emissions from industry, power plants, small equipment such as lawn

mowers and diesel generators. Frequent policy alternatives to emissions standards aretechnology standards (which mandate the use of a specific technology) andemission

trading.

Standards generally regulate the emissions ofnitrogen oxides (NOx), sulfur oxides,

particulate matter(PM) orsoot, carbon monoxide(CO), or volatile hydrocarbons(seecarbon dioxide equivalent).

[edit] Motor vehicles

[edit] Background

The first Indian emission regulations were idle emission limits which became effective in

1989. These idle emission regulations were soon replaced by mass emission limits forboth petrol (1991) and diesel (1992) vehicles, which were gradually tightened during the

1990s. Since the year 2000, India started adopting European emission and fuel

regulations for four-wheeled light-duty and for heavy-dc. Indian own emissionregulations still apply to two- and three-wheeled vehicles.

Current requirement is that all transport vehicles carry a fitness certificate that is renewed

each year after the first two years of new vehicle registration.

On October 6, 2003, the National Auto Fuel Policy has been announced, which envisagesa phased program for introducing Euro 2 - 4 emission and fuel regulations by 2010. The

implementation schedule of EU emission standards in India is summarized in Table 1.[1]

Table 1: Indian Emission Standards (4-Wheel Vehicles)

Standard Reference Date Region

India 2000 Euro 1 2000 Nationwide

Bharat Stage II Euro 2 2001 NCR*, Mumbai, Kolkata, Chennai
http://en.wikipedia.org/wiki/Pollutantshttp://en.wikipedia.org/wiki/Automobilehttp://en.wikipedia.org/wiki/Automobilehttp://en.wikipedia.org/wiki/Vehiclehttp://en.wikipedia.org/wiki/Vehiclehttp://en.wikipedia.org/wiki/Industryhttp://en.wikipedia.org/wiki/Electrical_generatorhttp://en.wikipedia.org/wiki/Electrical_generatorhttp://en.wikipedia.org/wiki/Emission_tradinghttp://en.wikipedia.org/wiki/Emission_tradinghttp://en.wikipedia.org/wiki/Emission_tradinghttp://en.wikipedia.org/wiki/NOxhttp://en.wikipedia.org/wiki/NOxhttp://en.wikipedia.org/wiki/NOxhttp://en.wikipedia.org/wiki/NOxhttp://en.wikipedia.org/wiki/Sulfur_oxideshttp://en.wikipedia.org/wiki/Particulate_matterhttp://en.wikipedia.org/wiki/Particulate_matterhttp://en.wikipedia.org/wiki/Soothttp://en.wikipedia.org/wiki/Carbon_monoxidehttp://en.wikipedia.org/wiki/Carbon_monoxidehttp://en.wikipedia.org/wiki/Hydrocarbonhttp://en.wikipedia.org/wiki/Hydrocarbonhttp://en.wikipedia.org/wiki/Carbon_dioxide_equivalenthttp://en.wikipedia.org/w/index.php?title=Bharat_Stage_emission_standards&action=edit&section=1http://en.wikipedia.org/w/index.php?title=Bharat_Stage_emission_standards&action=edit&section=2http://en.wikipedia.org/wiki/Bharat_Stage_emission_standards#cite_note-0%23cite_note-0http://en.wikipedia.org/wiki/Bharat_Stage_emission_standards#cite_note-0%23cite_note-0http://en.wikipedia.org/wiki/Pollutantshttp://en.wikipedia.org/wiki/Automobilehttp://en.wikipedia.org/wiki/Vehiclehttp://en.wikipedia.org/wiki/Industryhttp://en.wikipedia.org/wiki/Electrical_generatorhttp://en.wikipedia.org/wiki/Emission_tradinghttp://en.wikipedia.org/wiki/Emission_tradinghttp://en.wikipedia.org/wiki/NOxhttp://en.wikipedia.org/wiki/Sulfur_oxideshttp://en.wikipedia.org/wiki/Particulate_matterhttp://en.wikipedia.org/wiki/Soothttp://en.wikipedia.org/wiki/Carbon_monoxidehttp://en.wikipedia.org/wiki/Hydrocarbonhttp://en.wikipedia.org/wiki/Carbon_dioxide_equivalenthttp://en.wikipedia.org/w/index.php?title=Bharat_Stage_emission_standards&action=edit&section=1http://en.wikipedia.org/w/index.php?title=Bharat_Stage_emission_standards&action=edit&section=2http://en.wikipedia.org/wiki/Bharat_Stage_emission_standards#cite_note-0%23cite_note-0


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2003.04 NCR*, 10 Cities

2005.04 Nationwide

Bharat Stage III Euro 3

2005.04 NCR*, 10 Cities

2010.04 Nationwide

Bharat Stage IV Euro 4 2010.04 NCR*, 10 Cities

* National Capital Region (Delhi)

Mumbai, Kolkata, Chennai, Bengaluru, Hyderabad, Ahmedabad, Pune, Surat, Kanpur

and Agra

The above standards apply to all new 4-wheel vehicles sold and registered in the

respective regions. In addition, the National Auto Fuel Policy introduces certain emissionrequirements for interstate buses with routes originating or terminating in Delhi or the

other 10 cities.

For 2-and 3-wheelers, Bharat Stage II (Euro 2) will be applicable from April 1, 2005 and

Stage III (Euro 3) standards would come in force from April 1, 2010. [2]

[edit] Trucks and buses

Exhaust gases from vehicles form a significant portion of air pollution which is harmful

to human health and the environment

Emission standards for new heavy-duty diesel enginesapplicable to vehicles of GVW >3,500 kgare listed in Table 2.
http://en.wikipedia.org/wiki/Bharat_Stage_emission_standards#cite_note-1%23cite_note-1http://en.wikipedia.org/w/index.php?title=Bharat_Stage_emission_standards&action=edit&section=3http://en.wikipedia.org/wiki/File:Exhaust.jpghttp://en.wikipedia.org/wiki/File:Exhaust.jpghttp://en.wikipedia.org/wiki/Bharat_Stage_emission_standards#cite_note-1%23cite_note-1http://en.wikipedia.org/w/index.php?title=Bharat_Stage_emission_standards&action=edit&section=3


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Table 2 Emission Standards for Diesel Truck and Bus Engines, g/kWh

Year Reference Test CO HC NOx PM

1992 - ECE R49 17.3-32.6 2.7-3.7 - -

1996 - ECE R49 11.20 2.40 14.4 -

2000 Euro I ECE R49 4.5 1.1 8.0 0.36*

2005 Euro II ECE R49 4.0 1.1 7.0 0.15

2010 Euro III

ESC 2.1 0.66 5.0 0.10

ETC 5.45 0.78 5.0 0.16

2010 Euro IV

ESC 1.5 0.46 3.5 0.02

ETC 4.0 0.55 3.5 0.03

* 0.612 for engines below 85 kW

earlier introduction in selected regions, see Table 1 only in selected regions, see Table

1

More details on Euro I-III regulations can be found in the EU heavy-duty engine

standards page.

[edit] Light duty diesel vehicles

Emission standards for light-duty diesel vehicles (GVW 3,500 kg) are summarized inTable 3. Ranges of emission limits refer to different classes (by reference mass) of light

commercial vehicles; compare the EU light-duty vehicle emission standards page for
http://en.wikipedia.org/w/index.php?title=Bharat_Stage_emission_standards&action=edit&section=4http://en.wikipedia.org/w/index.php?title=Bharat_Stage_emission_standards&action=edit&section=4


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details on the Euro 1 and later standards. The lowest limit in each range applies to

passenger cars (GVW 2,500 kg; up to 6 seats).

Table 3 Emission Standards for Light-Duty Diesel Vehicles, g/km

Year Reference CO HC HC+NOx NOx PM

1992 - 17.3-32.6 2.7-3.7 - - -

1996 - 5.0-9.0 - 2.0-4.0 - -

2000 Euro 1 2.72-6.90 - 0.97-1.70 0.14-0.25 -

2005 Euro 2 1.0-1.5 - 0.7-1.2 0.08-0.17 -

2010 Euro 30.640.80

0.95

-0.560.72

0.86

0.500.65

0.78

0.050.07

0.10

2010 Euro 40.500.63

0.74

-0.300.39

0.46

0.250.33

0.39

0.0250.04

0.06

earlier introduction in selected regions, see Table 1

only in selected regions, see Table 1

The test cycle has been the ECE + EUDC for low power vehicles (with maximum speed

limited to 90 km/h). Before 2000, emissions were measured over an Indian test cycle.

Engines for use in light-duty vehicles can be also emission tested using an engine

dynamometer. The respective emission standards are listed in Table 4.

Table 4 Emission Standards for Light-Duty Diesel Engines, g/kWh


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Year Reference CO HC NOx PM

1992 - 14.0 3.5 18.0 -

1996 - 11.20 2.40 14.4 -

2000 Euro I 4.5 1.1 8.0 0.36*

2005 Euro II 4.0 1.1 7.0 0.15

* 0.612 for engines below 85 kW

earlier introduction in selected regions, see Table 1

[edit] Light duty gasoline vehicles

[edit] 4-wheel vehicles

Emissions standards for gasoline vehicles (GVW 3,500 kg) are summarized in Table 5.

Ranges of emission limits refer to different classes of light commercial vehicles (compare

the EU light-duty vehicle emission standards page). The lowest limit in each rangeapplies to passenger cars (GVW 2,500 kg; up to 6 seats).

Table 5 Emission Standards for Gasoline Vehicles (GVW 3,500 kg), g/km

Year Reference CO HC HC+NOx NOx

1991 - 14.3-27.1 2.0-2.9 -

1996 - 8.68-12.4 - 3.00-4.36

1998* - 4.34-6.20 - 1.50-2.18
http://en.wikipedia.org/w/index.php?title=Bharat_Stage_emission_standards&action=edit&section=5http://en.wikipedia.org/w/index.php?title=Bharat_Stage_emission_standards&action=edit&section=6http://en.wikipedia.org/w/index.php?title=Bharat_Stage_emission_standards&action=edit&section=5http://en.wikipedia.org/w/index.php?title=Bharat_Stage_emission_standards&action=edit&section=6


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2000 Euro 1 2.72-6.90 - 0.97-1.70

2005 Euro 2 2.2-5.0 - 0.5-0.7

2010 Euro 3

2.3

4.17

5.22

0.20

0.25

0.29

-

0.15

0.18

0.21

2010 Euro 4

1.0

1.81

2.27

0.1

0.13

0.16

-

0.08

0.10

0.11

* for catalytic converter fitted vehicles

earlier introduction in selected regions, see Table 1 only in selected regions, see Table

1

Gasoline vehicles must also meet an evaporative (SHED) limit of 2 g/test (effective

2000).

[edit] 3- and 2-wheel vehicles

Emission standards for 3- and 2-wheel gasoline vehicles are listed in the following tables.[3]

Table 6 Emission Standards for 3-Wheel Gasoline Vehicles, g/km

Year CO HC HC+NOx

1991 12-30 8-12 -

1996 6.75 - 5.40

2000 4.00 - 2.00
http://en.wikipedia.org/w/index.php?title=Bharat_Stage_emission_standards&action=edit&section=7http://en.wikipedia.org/wiki/Bharat_Stage_emission_standards#cite_note-2%23cite_note-2http://en.wikipedia.org/w/index.php?title=Bharat_Stage_emission_standards&action=edit&section=7http://en.wikipedia.org/wiki/Bharat_Stage_emission_standards#cite_note-2%23cite_note-2


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2005 (BS II) 2.25 - 2.00

2010.04 (BS III) 1.25 - 1.25

Table 7 Emission Standards for 2-Wheel Gasoline Vehicles, g/km

Year CO HC HC+NOx

1991 12-30 8-12 -

1996 5.50 - 3.60

2000 2.00 - 2.00

2005 (BS II) 1.5 - 1.5

2010.04 (BS III) 1.0 - 1.0

Table 8 Emission Standards for 2- And 3-Wheel Diesel Vehicles, g/km

Year CO HC+NOx PM

2005.04 1.00 0.85 0.10

2010.04 0.50 0.50 0.05

[edit] Overview of the emission norms in India

1991 - Idle CO Limits for Gasoline Vehicles and Free Acceleration Smoke for

Diesel Vehicles, Mass Emission Norms for Gasoline Vehicles.

1992 - Mass Emission Norms for Diesel Vehicles.


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1996 - Revision of Mass Emission Norms for Gasoline and Diesel Vehicles,

mandatory fitment of Catalytic Converter for Cars in Metros on Unleaded

Gasoline.

1998 - Cold Start Norms Introduced.

2000 - India 2000 (Eq. to Euro I) Norms, Modified IDC (Indian Driving Cycle),

Bharat Stage II Norms for Delhi. 2001 - Bharat Stage II (Eq. to Euro II) Norms for All Metros, Emission Norms for

CNG & LPG Vehicles.

2003 - Bharat Stage II (Eq. to Euro II) Norms for 11 major cities.

2005 - From 1 April Bharat Stage III (Eq. to Euro III) Norms for 11 major cities.

2010 - Bharat Stage III Emission Norms for 4-wheelers for entire country whereas

Bharat Stage - IV (Eq. to Euro IV) for 11 major cities. Bharat Stage IV also has

norms on OBD (similar to Euro III but diluted)

[edit] CO2 emission

Indias auto sector accounts for about 18 per cent of the total CO2 emissions in thecountry. Relative CO2 emissions from transport have risen rapidly in recent years, but

like the EU, currently there are no standards for CO2 emission limits for pollution fromvehicles.

[edit] Obligatory labeling

There is also no provision to make the CO2 emissions labeling mandatory on cars in the

country. A system exists in the EU to ensure that information relating to the fueleconomy and CO2 emissions of new passenger cars offered for sale or lease in the

Community is made available to consumers in order to enable consumers to make an

informed choice.

[edit] Non road diesel engines

[edit] Construction machinery

Emission standards for diesel construction machinery were adopted on 21 September

2006. The standards are structured into two tiers:

Bharat (CEV) Stage IIThese standards are based on the EU Stage I

requirements, but also cover smaller engines that were not regulated under the EU

Stage I. Bharat (CEV) Stage IIIThese standards are based on US Tier 2/3 requirements.

The standards are summarized in the following table:

Table 9 Bharat (CEV) Emission Standards for Diesel Construction Machinery
http://en.wikipedia.org/w/index.php?title=Bharat_Stage_emission_standards&action=edit&section=9http://en.wikipedia.org/w/index.php?title=Bharat_Stage_emission_standards&action=edit&section=10http://en.wikipedia.org/w/index.php?title=Bharat_Stage_emission_standards&action=edit&section=11http://en.wikipedia.org/w/index.php?title=Bharat_Stage_emission_standards&action=edit&section=12http://en.wikipedia.org/w/index.php?title=Bharat_Stage_emission_standards&action=edit&section=9http://en.wikipedia.org/w/index.php?title=Bharat_Stage_emission_standards&action=edit&section=10http://en.wikipedia.org/w/index.php?title=Bharat_Stage_emission_standards&action=edit&section=11http://en.wikipedia.org/w/index.php?title=Bharat_Stage_emission_standards&action=edit&section=12


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Engine Power

Date

CO HC HC+NOx NOx PM

kW g/kWh

Bharat (CEV) Stage II

P < 8 2008.10 8.0 1.3 - 9.2 1.00

8 P < 19 2008.10 6.6 1.3 - 9.2 0.85

19 P < 37 2007.10 6.5 1.3 - 9.2 0.85

37 P < 75 2007.10 6.5 1.3 - 9.2 0.85

75 P < 130 2007.10 5.0 1.3 - 9.2 0.70

130 P < 560 2007.10 5.0 1.3 - 9.2 0.54

Bharat (CEV) Stage III

P < 8 2011.04 8.0 - 7.5 - 0.80

8 P < 19 2011.04 6.6 - 7.5 - 0.80

19 P < 37 2011.04 5.5 - 7.5 - 0.60

37 P < 75 2011.04 5.0 - 4.7 - 0.40

75 P < 130 2011.04 5.0 - 4.0 - 0.30


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130 P < 560 2011.04 3.5 - 4.0 - 0.20

The limit values apply for both type approval (TA) and conformity of production (COP)

testing. Testing is performed on an engine dynamometer over the ISO 8178 C1 (8-mode)and D2 (5-mode) test cycles. The Bharat Stage III standards must be met over the useful

life periods shown in Table 10. Alternatively, manufacturers may use fixed emissiondeterioration factors of 1.1 for CO, 1.05 for HC, 1.05 for NOx, and 1.1 for PM.

Table 10 Bharat (CEV) Stage III Useful Life Periods

Power Rating

Useful Life Period

hours

< 19 kW 3000

19-37 kW

constant speed 3000

variable speed 5000

> 37 kW 8000

[edit] Agricultural tractors

Emission standards for diesel agricultural tractors are summarized in Table 11.

Table 11 Indian Emission Standards (4-Wheel Vehicles)

Standard Reference Date Region

India 2000 Euro 1 2000 Nationwide
http://en.wikipedia.org/wiki/ISO_8178http://en.wikipedia.org/w/index.php?title=Bharat_Stage_emission_standards&action=edit&section=13http://en.wikipedia.org/wiki/ISO_8178http://en.wikipedia.org/w/index.php?title=Bharat_Stage_emission_standards&action=edit&section=13


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Bharat Stage II Euro 2

2001 NCR*, Mumbai, Kolkata, Chennai

2003.04 NCR*, 11 Cities

2005.04 Nationwide

Bharat Stage III Euro 3

2005.04 NCR*, 11 Cities

2010.04 Nationwide

Bharat Stage IV Euro 4 2010.04 NCR*, 11 Cities

* National Capital Region (Delhi)

Mumbai, Kolkata, Chennai, Bangalore, Hyderabad, Secunderabad, Ahmedabad, Pune,Surat, Kanpur and Agra

Emissions are tested over the ISO 8178 C1 (8-mode) cycle. For Bharat (Trem) Stage IIIA, the useful life periods and deterioration factors are the same as for Bharat (CEV) Stage

III, Table 10.

[edit] Electricity generation

[edit] Generator sets

Emissions from new diesel engines used in generator sets have been regulated by theMinistry of Environment and Forests, Government of India [G.S.R. 371 (E), 17 May

2002]. The regulations impose type approval certification, production conformity testing

and labeling requirements. Certification agencies include the Automotive ResearchAssociation of India and the Vehicle Research and Development Establishment. The

emission standards are listed below.

Table 12 Emission Standards for Diesel Engines 800 kW for Generator Sets

Engine Power (P) Date CO HC NOx PM Smoke
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g/kWh 1/m

P 19 kW

2004.01 5.0 1.3 9.2 0.6 0.7

2005.07 3.5 1.3 9.2 0.3 0.7

19 kW < P 50 kW

2004.01 5.0 1.3 9.2 0.5 0.7

2004.07 3.5 1.3 9.2 0.3 0.7

50 kW < P 176 kW 2004.01 3.5 1.3 9.2 0.3 0.7

176 kW < P 800 kW 2004.11 3.5 1.3 9.2 0.3 0.7

Engines are tested over the 5-mode ISO 8178 D2 test cycle. Smoke opacity is measured

at full load.

Table 13 Emission Limits for Diesel Engines > 800 kW for Generator Sets

Date

CO NMHC NOx PM

mg/Nm3 mg/Nm3 ppm(v) mg/Nm3

Until 2003.06 150 150 1100 75

2003.07 - 2005.06 150 100 970 75

2005.07 150 100 710 75

Concentrations are corrected to dry exhaust conditions with 15% residual O2.


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[edit] Power plants

The emission standards for thermal power plants in India are being enforced based on

Environment (Protection) Act, 1986 of Government of India and its amendments fromtime to time.[4] A summary of emission norms for coal and gas based thermal power

plants is given in Tables 14 and 15

Table 14 Environmental standards for coal & gas based power plants

Capacity Pollutant Emission limit

Coal based thermal plants

Below 210 MW Particulate matter (PM) 350 mg/Nm3

210 MW & above 150 mg/Nm3

500 MW & above 50 mg/Nm3

Gas based thermal plants

400 MW & aboveNOX(V/V at 15%excess oxygen)

50 PPM for natural gas; 100

PPM for

naphtha

Below 400 MW & up to 100MW

75 PPM for natural gas; 100PPM for

naphtha

Below 100 MW 100 PPM for naphtha/natural gas

For conventional boilers 100 PPM

Table 15 Stack height requirement for SO2 control

Power Generation Capacity Stock Height (Metre)

Less than 200/210 MWe

H = 14 (Q)0.3 where Q is emission

rate of SO 2 in kg/hr,H = Stack height in metres

200/210 MWe

or less than 500 MWe 200 200

500 MWe and

above

275 (+ Space provision for FGD

systems in future)

The norms for 500 MW and above coal based power plant being practised is 40 to50 mg/Nm and space is provided in the plant layout for super thermal power stations for

installation of flue gas desulphurisation (FGD) system. But FGD is not installed, as it is

not required for low sulphur Indian coals while considering SO X emission fromindividual chimney.
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In addition to the above emission standards, the selection of a site for a new power plant

has to maintain the local ambient air quality as given in Table 16.

Table 16 Ambient air quality standard

Category

Conc. g/m3

SPM SO2 CO NOX

Industrial and mixed-use 500 120 5000 120

Residential and rural 200 80 2000 80

Sensitive 100 30 1000 30

Table 17 World bank norms for new projects

Existing Air Quality Recommendation

SOX > 100 ?

g/m3 No project

SOX = 100 ?

g/m3

Polluted area, max. from a project

100 t/day

SOX < 50 ?

g/m3

Unpolluted area, max. from a project

500 t/day

However the norms for SOX are even stricter for selection of sites for World Bank

funded projects (refe r Table 2.4). For example, if SOX level is higher than 100 ? g/m 3,

no project with further SOX emission can be set up; if SO X level is 100 ? g/m 3, it is

called polluted area and maximum emission from a project should not exceed 100 t/day;and if SOX is less than 50 ? g/m 3, it is called unpolluted area, but the SOX emission

from a project should not exceed 500 t/day. The stipulation for NOX emission is that its

emission should not exceed 260 gram s of NOX per giga joule of heat input.

In view of the above, it may be seen that improved environment norms are linked tofinancing and are being enforced by international financial institutions and not by the

policies/laws of land.

[edit] Fuels

Fuel Quality plays a very important role in meeting the stringent emission regulation.


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The fuel specifications of Gasoline and Diesel have been aligned with the Corresponding

European Fuel Specifications for meeting the Euro II, Euro III and Euro IV emission

norms.

The use of alternative fuels has been promoted in India both for energy security and

emission reduction Delhi and Mumbai have more than 100,000 commercial vehiclesrunning on CNG fuel. Delhi has the largest number of CNG commercial vehicles running

any where in the World. India is planning to introduce Biodiesel, Ethanol Gasolineblends in a phased manner and has drawn up a road map for the same. The Indian auto

Industry is working with the authorities to facilitate for introduction of the alternative

fuels. India has also setup a task force for preparing the Hydrogen road map. The use ofLPG has also been introduced as an auto fuel and the oil industry has drawn up plans for

setting up of Auto LPG dispensing station in major cities.

Indian Gasoline specifications:

Table 18

Sl.No

Characteristics UnitBharat

Stage II

Bharat

Stage III

Bharat

Stage IV

1 Density 15 0 C Kg/m3 710-770 720-775 720-775

2 Distillation

3

a) Recovery up to 70 0 C(E70)

b) Recovery up to 100 0 C (E100)

c) Recovery up to 180 0 C (E180)

d) Recovery up to 150 0 C (E150)

e) Final Boiling Point (FBP), Max

f) Residue Max

%Volume

%Volume

%Volume

%Volume

0C

% Volume

10-45

40-70

90

-

210

2

10-45

40-70

-

75min

210

2

10-45

40-70

-

75min

210

2

4Research Octane Number(RON), Min

88 91 91

5Anti Knock Index (AKI)/ MON,Min

84 (AKI) 81 (MON) 81 (MON)

6 Sulphur, Total , Max % mass 0.05150

mg/Kg50mg/Kg

7 Lead Content(as Pb), Max g/l 0.013 0.005 0.005

8 Reid Vapour Pressure (RVP), Kpa 35-60 60 60


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Max

9

Benzene, Content, Max

a) For Metros

b) For the rest

% Volume

-

3

5

1 1

10 Olefin content, Max % Volume - 21 21

11 Aromatic Content, Max % Volume - 42 35

Indian diesel specifications:

Table 19

S. No Characteristic BSII BSIII BSIV

1 Density Kg/m3 15 0 C 820-800 820-845 820-845

2 Sulphur Content mg/kg max 500 350 50

3(a)

3(b)

Cetane Number minimum and / or

Cetane Index

48

or 46

51

and 46

51

and 464 Polycyclic Aromatic Hydrocarbon - 11 11

5

(a)

(b)

(c)

Distillation

Reco. Min. At 350 0 C

Reco. Min. At 370 0C

95%Vol Reco at 0o C max

85

95

-

-

-

360

-

-

360

Table 20 Diesel Fuel Quality in India

Date Particulars


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199

5Cetane number: 45; Sulfur: 1%

1996

Sulfur: 0.5% (Delhi + selected cities)

1998

Sulfur: 0.25% (Delhi)

199

9Sulfur: 0.05% (Delhi, limited supply)

200

0Cetane number: 48; Sulfur: 0.25% (Nationwide)

2001

Sulfur: 0.05% (Delhi + selected cities)

200

5Sulfur: 350 ppm (Euro 3; selected areas)

201

0Sulfur: 350 ppm (Euro 3; nationwide)

2010

Sulfur: 50 ppm (Euro 4; selected areas)

Indian bio-diesel specifications:

Table 21

S.No. Characteristics Requirement Method of Test ,


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ref to

Other Methods[P:] of IS

1448

(1) (2) (3) (4) (5)

i. Density at 15C, kg/m3 860-900 ISO 3675 P:16/

ISO 12185 P:32

ASTM

ii. Kinematic Viscosity at 40C, cSt 2.5-6.0 ISO 3104 P:25

iii. Flash point (PMCC) C, min 120 P:21

iv. Sulphur, mg/kg max. 50.0 ASTM D 5453 P:83

vCarbon residue (Ramsbottom) *,%

by mass, max0.05

ASTM D 4530ISO

10370-

vi. Sulfated ash, % by mass, max 0.02 ISO 6245 P:4

vii. Water content, mg/kg, max 500 ASTM D 2709 P:40

ISO 3733

ISO 6296


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viii Total contamination, mg/kg, max 24 EN 12662 -

ix Cu corrosion, 3 hrs at 50C, max 1 ISO 2160 P:15

x Cetane No., min 51 ISO 5156 P:9

xi Acid value, mg KOH/g, max 0.50 - P:1 / Sec 1

xii Methanol @, % by mass, max 0.20 EN 14110 -

xiii Ethanol, @@ % by mass, max 0.20 -

xiv Ester content, % by mass, min 96.5 EN 14103 -

xv Free Glycerol, % by mass, max 0.02 ASTM D 6584 -

xvi Total Glycerol, % by mass, max 0.25 ASTM D 6584 -

xvii Phosphorous, mg/kg, max 10.0 ASTMD 4951 -

xviii Sodium & Potassium, mg/kg, max To report EN 14108 & -

EN 14109 -

xix Calcium and Magnesium, mg/kg,max

To report -

xx Iodine value To report EN 14104 -


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xxiOxidation stability, at 110C hrs,

min6 EN 14112 -

* Carbon residue shall be run on 100% sample

** European method is under development

@ Applicable for Fatty Acid Methyl Ester

@@ Applicable for Fatty Acid Ethyl Ester

Gear cutting

[edit] Processes

[edit] Broaching

Main article: Broaching

For very large gears orsplines, a vertical broach is used. It consists of a vertical rail that

carries a single tooth cutter formed to create the tooth shape. A rotary table and a Y axisare the customary axes available. Some machines will cut to a depth on the Y axis and

index the rotary table automatically. The largest gears are produced on these machines.

Other operations such as broaching work particularly well for cutting teeth on the inside.

The downside to this is that it is expensive and different broaches are required to makedifferent sized gears. Therefore it is mostly used in very high production runs.

[edit] Hobbing

Main article: Hobbing

Hobbing is a method by which a hob is used to cut teeth into a blank. The cutter and gear

blank are rotated at the same time to transfer the profile of the hob onto the gear blank.The hob must make one revolution to create each tooth of the gear. Used very often for

all sizes of production runs, but works best for medium to high.

[edit] Machining

Main article: Machining
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Spurmay be cut orground on a milling machine orjig grinderutilizing a numbered gear

cutter, and any indexing head or rotary table. The number of the gear cutter is determined

by the tooth count of the gear to be cut.

To machine a helical gearon a manual machine, a true indexing fixture must be used.

Indexing fixtures can disengage the drive worm, and be attached via an externalgeartrain to the machine table's handle (like a power feed). It then operates similarly to a

carriage on a lathe. As the table moves on the X axis, the fixture will rotate in a fixedratio with the table. The indexing fixture itself receives its name from the original

purpose of the tool: moving the table in precise, fixed increments. If the indexing worm is

not disengaged from the table, one can move the table in a highly controlled fashion viathe indexing plate to produce linear movement of great precision (such as a vernier

scale).

There are a few different types of cutters used when creating gears. One is a rack shaper.

These are straight and move in a direction tangent to the gear, while the gear is fixed.

They have six to twelve teeth and eventually have to be moved back to the starting pointto begin another cut.

A popular way to build gears is by form cutting. This is done by taking a blank gear and

rotating a cutter, with the desired tooth pattern, around its periphery. This ensures that thegear will fit when the operation is finished.

[edit] Shaping

Main article: Gear shaper

The old method of gear cutting is mounting a gear blank in a shaperand using a tool

shaped in the profile of the tooth to be cut. This method also works for cutting internalsplines.

Another is a pinion-shaped cutter that is used in a gear shaper machine. It is basically

when a cutter that looks similar to a gear cuts a gear blank. The cutter and the blank musthave a rotating axis parallel to each other. This process works well for low and high

production runs.

[edit] Finishing

After being cut the gear can be finished byshaving,burnishing, grinding, honingor

lapping.[1]

Pistons and Rings

Piston rings are not difficult to make IF you have the necessary formulae. There is a fineline between a piston ring which works, and another which is too weak (compressive wall
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force), too stiff (impossible to install without breakage), or otherwise unsuitable. The

finest treatise on making custom piston rings can be found in the magazine Strictly IC,

issues 7, 8, and 9. Editor Bob Washburn has all of the back issues. The author of theseries on piston ring construction is Mr. George Trimble, and he approached the subject

scientifically, deriving a method which will make great rings forany IC engine. The

method makes use of a mandrel which holds the rings spread for heat treatment, and isbased on ratios of ring thickness to bore.

The first step in preparing rings is to

rough out (and then polish) the

outside diameter of the rings from afine-grained cast-iron bar. Tolerance

is +.0006, -.0000. UNDERSIZED

RINGS are a no-no, and will notwork. The bore size of all my

cylinders is 1.0003", +.0002, -.0002.

Hence I needed this bar to measure1.0005" minimum. I shot for1.0005". The bar is turned to

1.0015", and the taper carefully

measured. In my case it tapered .0004". I used silicon carbide wet-dry

paper in grits 320, 600, 1200, 1500,

and 2000 to SLOWLY remove thetaper and polish the bar to a mirror

finish. The paper is backed with a

hardened steel parallel. Final

dimension was within .0001throughout the length.

The bore of the ring stock is cut. The

grooves already cut in the piston

measure .904" diameter. I elected tobore the ring stock to .914 to provide

plenty of clearance. Final cuts were

taken with a very minimal feed toremove spring from the tool, maybe

3 passes for the final .005". Internal

taper was negligible.

Note the high finish on the OD of thering stock compared to the turned

finish in the above photo.


32/37

A mini-thin parting tool of width .

027" was used to part the individual

rings. Before parting, the outer rim isdeburred with a hard arkansas stone,

and partway through the stock, the

tool is withdrawn and the inner ODrim is deburred as well. The ID rims

are deburred after parting with a

Cratex rubberized abrasive mounted

in a Foredom hand tool. My engineuses 2 rings per piston... I planned on

36 rings, as many will be scrapped

for one reson or another. The whitestuff inside the bore is a paper towel

shoved in to control ringing and

chatter during parting.

After parting, thefaces of the ringsare lapped on a surface plate with

progressively finer wet-dry, with

2000 grit producing a mirror finish.

The mandrel is shown here,constructed of 1018 steel with the

formula derived from the SIC

articles. Basically, the formulas giveyou the large mandrel size, the small

dowel size (the small dowel opens

the ring) and the distance betweencenters of the two.

The rings, after polishing, are split

with ordinary wire cutters. This will

usually cleave them cleanly, butperhaps one in ten will be discarded

due to a jagged, uneven break. The

survivors are slowly spread andmounted on the mandrel. The whole

assy is then heated to 1475 deg. f. for

1/2 hour. Scale prevention isimportant... I used a double-wrapping of SS foil, with Nitrogen

gas injected before sealing. I have

used keepbryte in the past whichworks, but the SS foil is neater and

easier to use.


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After heat treatment, the rings retain

their expanded set. The dark color is

not scale... I was a bit anxious toopen the SS envelope, and the whole

assy was hot enough to darken the

rings a bit. If you look closely, youcan still see some rings mounted at

the base of the mandrel. Note the gap

in the loose rings... this is the set of

the rings, notthe traditional ring gapwhich must be cut after the rings are

inserted into a bore.

Two pistons with ring grooves cut

but without rings. The top groove ispurely compression... the bottom

groove is a combination compression

and oil-control setup. Note the holesdrilled axially. These holes are

drilled after a band perhaps .005"

deep is turned in the piston, anddrain to the wrist pin cavity seen in

the right hand piston. The lower ring

scrapes the oil into this shallow

groove, where it is forced backinside the piston.

A piston ring is an open-ended ring that fits into a groove on the outer diameter of a

piston in a reciprocating enginesuch as aninternal combustion engineorsteam engine.

The three main functions of piston rings in reciprocating engines are:

1. Sealing the combustion/expansion chamber.

2. Supporting heat transfer from the piston to the cylinder wall.3. Regulating engine oil consumption.[4][1]

The gap in the piston ring compresses to a few thousandths of an inch when inside the

cylinder bore.

[edit] Automotive

Most automotive pistons have three rings: The top two while also controlling oil are

primarily for compression sealing (compression rings); the lower ring is for controlling

the supply of oil to the liner which lubricates the piston skirt and the compression rings

(oil control rings). Typical compression ring designs will have an essentially rectangularcross section or a keystone cross section. The periphery will then have either a barrel
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profile (top compression rings) or a taper napier form (second compression rings). There

are some taper faced top rings and on some old engines simple plain faced rings were

used.

Oil control rings typically are of three types: (1) single piececast iron, (2) helical spring

backed cast iron or steel, or (3) multipiece steel. The spring backed oil rings and the castiron oil rings have essentially the same range of peripheral forms which consist of two

scraping lands of various detailed form. The multipiece oil control rings usually consistof two rails or segments (these are thin steel rings) with a spacer expander spring which

keeps the two rails apart and provides the radial load.

[edit] Wear due to ring load on the bore

Piston rings are subject to wear as they move up and down the cylinder bore due to theirown inherent load and due to the gas load acting on the ring. To minimize this, they are

made of wear-resistant materials, such as cast iron and steel, and are coated or treated to

enhance the wear resistance. Two-stroke port design is critical to ring life. Newer modernmotorcycle manufacturers have many single function but serrated ports to retain the ring.

Typically, top ring and oil control rings will be coated with Chromium[2] , orNitrided[5],

possibly plasma sprayed[6]or have a PVD (physical vapour deposit)[3]ceramic coating.

For enhanced scuff resistance and further improved wear, most moderndiesel engineshave top rings coated with a modified chromium coating known as CKS[4] or GDC[7], a

patent coating from Goetze which has aluminium oxide or diamond particles respectively

included in the chrome surface. The lower oil control ring is designed to leave alubricating oil film, a few micrometres thick on the bore, as the piston descends. Three

piece oil rings, i.e. with two rails and one spacer, are used for four-stroke gasoline

engines.

[edit] Fitting new piston rings

When fitting new piston rings, orbreakingthem in within an engine, the end gap is a

crucial measurement. In order that a ring may be fitted into the "grooves" of the piston, it

is not continuous but is broken at one point on its circumference. The ring gap may bechecked by putting the ring into the bore/liner (squared to bore) and measuring with a

feeler gauge. End gap should be within recommended limits for size of bore and intended

"load" of engine. Metals expand with a rise in temperature, so too small a gap may result

in overlapping or bending when used under hot running conditions (racing, heavy loads,towing), and even at normal temperatures, a small ring gap may lead to ring gap closure,

ring breakage, bore damage and possible seizure of the piston. Too large a gap may giveunacceptable compression and levels ofblow-by gasses or oil consumption. When beingmeasured in a used bore it may indicate excessive bore wear or ring wear.(Radial wear on

ring face reduces thickness of used/worn ring (face wear in bore) essentially decreasing

face circumference of ring and thereby increasing size of ring end gap.)

When fitting new rings to a used engine, special "ridge dodger" rings are sometimes usedfor the top compression ring, to improve compression and oil consumption without
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reboring the cylinder. These have a small step of iron removed from the top section to

avoid making contact with any wear ridge at the top of the cylinder, which could break a

conventional ring. Generally, these are not recommended as they are probably notrequired and may give inferior oil consumption. A more acceptable method is to remove

the wear ridge with a "ridge reamer" tool before lightly honing thebore to accept new

rings. In fact if the "ridge " is measured it will generally be apparent it is not really aridge but a relatively local hollow caused by the top ring near the ring reversal point. The

upper edge of this hollow will take the form or a "ramp" about 2mm long from the point

of maximum wear to the point of zero wear. In this case there is not actually any ridge tohit, so light honing may be all that is required.

Piston

A piston is a component ofreciprocating engines,pumps and gas compressors. It is

located in a cylinderand is made gas-tight bypiston rings. In an engine, its purpose is to

transfer force from expanding gas in the cylinder to the crankshaft via apiston rodand/orconnecting rod. In a pump, the function is reversed and force is transferred from the

crankshaft to the piston for the purpose of compressing or ejecting the fluid in thecylinder. In some engines, the piston also acts as avalve by covering and uncovering

ports in the cylinder wall.

[edit] Piston engines

Main article: Reciprocating engine

[edit] Internal combustion engines

There are two ways that aninternal combustionpiston engine can transform combustioninto motive power: the two-stroke cycle and the four-stroke cycle. A single-cylinder two-

stroke engine produces power every crankshaft revolution, while a single-cylinder four-

stroke engine produces power once every two revolutions. Older designs of small two-stroke engines produced more pollution than four-stroke engines. However, modern two-

stroke designs, like the Vespa ET2 Injectionutilisefuel-injectionand are as clean as four-

strokes. Large diesel two-stroke engines, as used in ships and locomotives, have alwaysused fuel-injection and produce low emissions. One of the biggest internal combustion

engines in the world, the Wrtsil-Sulzer RTA96-C is a two-stroke; it is bigger than most

two-storey houses, has pistons nearly 1 metre indiameterand is one of the most efficient

mobile engines in existence. In theory, a four-stroke engine has to be larger than a two-

stroke engine to produce an equivalent amount of power. Two-stroke engines arebecoming less common in developed countries these days, mainly due to manufacturer

reluctance to invest in reducing two-stroke emissions. Traditionally, two-stroke engineswere reputed to need more maintenance (despite exceptions like theRicardo Dolphin

engine, and the Twingle engines of the Trojan carand the Puch 250 motorcycle). Even

though the simplest two-stroke engines have fewer moving parts, they could wear outfaster than four-stroke engines. However fuel-injected two-strokes achieve better engine

lubrication, also cooling and reliability should improve considerably.
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Gallery

A piston and its

connecting rod.

CAD drawing of

crankshaft and pistons.

Large pistons (over

0.5 m incl.

connecting rod).

Simplified piston

animation.

Two-stroke enginewith

atuned expansion pipe

[edit] Steam engines

Steam engines are usually double-acting (i.e. steam pressure acts alternately on each side

of the piston) and the admission and release of steam is controlled by slide valves,piston

valves orpoppet valves.

[edit] Air cannons

The lists in this article may contain items that are not notable,encyclopedic, orhelpful. Please help outby removing such elements and incorporating

appropriate items into the main body of the article. (November 2008)

There are two special type of pistons used in air cannons: close tolerance piston anddouble piston. While in close tolerance piston,O-ringsare used as valve but in double

piston, O-rings are not used.

There are some features of close tolerance piston mentioned below:

1. Piston can swell and stick.2. Fits tightly in the cylinder.

3. Tight tolerance fit.4. Properties alter due to atmospheric change.

5. Backlash may such,some of the bin material into the valve which also can causethe piston to stick.

Common features of double piston:

1. Cannot swell and stick.
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2. Fits loosely in the cylinder.

3. No tight tolerance fit.

4. Properties are not altered due to atmospheric change.5. Two depression on the top of the piston so make enough clearance.

6. Even if foreign material enters the valve,the double piston does not stick.

[edit] Drawbacks

This section may require cleanup to meet Wikipedia's quality standards.Please improve this section if you can. (March 2009)

Since the piston is the main reciprocating part of an engine, its movement creates an

imbalance. This imbalance generally manifests itself as a vibration, which causes theengine to be perceivably harsh. The fricti

39987653 fuel injection notes

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