Previously, all ventures in to space were achieved with giant rockets which, after a certain amount of time , were directed back in to the earth’s atmosphere to be reduced to a cinder by the enormous heat of re entry –after the crew and their capsule had been ejected virtually all of that tremendously expensive equipment was destroyed after only one use.
Following are the main supporting systems of a space shuttle.
1. Propulsion system
2. External fuel tank
3. Space shuttle orbiter
A gate valve is a valve that opens by lifting a round or rectangular gate out of the path of the fluid. The distinct feature of a gate valve is the sealing surfaces between the gate and seats are planar. The gate faces can form a wedge shape or they can be parallel. Gate valves are sometimes used for regulating flow, but many are not suited for that purpose, having been designed to be fully opened or closed. When fully open, the typical gate valve has no obstruction in the flow path, resulting in very low friction loss.
Bonnets provide leakproof closure for the valve body. Gate valves may have a screw-in, union, or bolted bonnet. Screw-in bonnet is the simplest, offering a durable, pressure-tight seal. Union bonnet is suitable for applications requiring frequent inspection and cleaning. It also gives the body added strength. Bolted bonnet is used for larger valves and higher pressure applications.
Another type of bonnet construction in a gate valve is pressure seal bonnet. This construction is adopted for valves for high pressure service, typically in excess of 2250 psi. The unique feature about the pressure seal bonnet is that the body - bonnet joints seals improves as the internal pressure in the valve increases, compared to other constructions where the increase in internal pressure tends to create leaks in the body-bonnet joint.
In the field of massive and complex manufacturing we are now in need of materials, with properties, that can be manipulated according to our needs. Smart materials are one among those unique materials, which can change its shape or size simply by adding a little bit of heat, or can change from a liquid to a solid almost instantly when near a magnet. These materials include piezoelectric materials, magneto-rheostatic materials, electro-rheostatic materials, and shape memory alloys. Shape memory alloys are metals, which exhibit two very unique properties, pseudo-elasticity (an almost rubber-like flexibility, under-loading), and the shape memory effect (ability to be severely deformed and then return to its original shape simply by heating). The two unique properties described above are made possible through a solid state phase change that is a molecular rearrangement, in which the molecules remain closely packed so that the substance remains a solid. The two phases, which occur in shape memory alloys, are Martensite, and Austenite.
Nanotechnology, development and production of artefacts in which a dimension of less than 100 nanometres (nm) is critical to functioning (1 nm = 10-9 m/40 billionths of an inch). Nanotechnology is a hybrid science combining engineering and chemistry. Atoms and molecules stick together because they have complementary shapes that lock tog- ether, or charges that attract. As millions of these atoms are pieced together by nanomachines, a specific product will begin to take shape. The goal of nanotechnology is to manipulate atoms individually and place them in a pattern to produce a desired structure. Nanotechnology is likely to change the way almost everything, including medicine, computers and cars, are designed and constructed. Nanotechnology holds out the promise of materials of precisely specified composition and properties, which could yield structures of unprecedented strength and computers of extraordinary compactness and power. Nanotechnology may lead to revolutionary methods of atom-by-atom manufacturing and to surgery on the cellular scale. Scientists have made some progress at building devices, including computer components, at nanoscales. Nanotechnology is anywhere from five to 15 years in the future.
For years, the trusty seatbelts provided the sole form of passive restraints in our car. There were debates about their safety, especially related to children, but over time, much of the country adopted mandatory seat-belt laws. Statistics have show that seat-belts have saved thousands of lives that might have been lost in collisions.Airbags have been under development for many years. The first commercial airbags appeared in automobiles in the 1980s.They are a proven safety device that save a growing number of lives, and prevent a large number of head and chest injuries. They are reducing driver deaths by 14 percent and passenger bags reduce deaths by about 11 percent.
People who use seat-belts think they do not need airbags. But they do. Airbags and lap/shoulder belts work together as a system, and one without the other isn't as effective. Deaths are 12 percent lower among drivers with belts and 9 percent lower among belted passengers.
Since model year, all new cars have been required to have airbags on both driver and passenger sides. Light trucks came under the rule in 1999.Newer than steering-wheel-mounted or dashboard-mounted bags are seat-mounted door-mounted and window airbags. Airbags are subject of serious government and industry researches and tests.
Airbags can cause some unintended adverse effects. Nearly all of these are minor injuries like bruises and abrasions that are more than offset by the lives airbags are saving.You can eliminate this risk, and position is what counts. Serious inflation injuries occur primarily because of peoples position when airbags first begin inflating.
Stopping an objects momentum requires force acting over a period of time. When a car crashes the force required to stop an object is very great because the car's momentum has changed instantly while the passengers has not. The goal of any supplement restraint system is to help stop the passengers while doing as little damage to him or her as possible.
What an airbag want to do is to slow down the passenger's speed to zero with little or no damage .The constraints that it has to work are huge .The airbag has the space between the passenger and the steering wheel or dashboard and a fraction of a second to work with. Even that tiny amount of space and time is valuable
The cam has been an integral part of the IC engine from its invention. The cam controls the "breathing channels" of the IC engines, that is, the valves through which the fuel air mixture (in SI engines) or air (in CI engines) is supplied and exhaust driven out.
Besieged by demands for better fuel economy, more power, and less pollution, motor engineers around the world are pursuing a radical "camless" design that promises to deliver the internal-combustion engine's biggest efficiency improvement in years. The aim of all this effort is liberation from a constraint that has handcuffed performance since the birth of the internal-combustion engine more than a century ago. Camless engine technology is soon to be a reality for commercial vehicles. In the camless valvetrain, the valve motion is controlled directly by a valve actuator - there's no camshaft or connecting mechanisms. Precise electronic circuit controls the operation of the mechanism, thus bringing in more flexibility and accuracy in opening and closing the valves. The seminar looks at the working of the electronically controlled camless engine, its general features and benefits over conventional engine.
The engines powering today's vehicles, whether they burn gasoline or diesel fuel, rely on a system of valves to admit fuel and air to the cylinders and to let exhaust gases escape after combustion. Rotating steel camshafts with precision-machined egg-shaped lobes, or cams, are the hard-tooled "brains" of the system. They push open the valves at the proper time and guide their closure, typically through an arrangement of pushrods, rocker arms, and other hardware. Stiff springs return the valves to their closed position
From the day machines with reciprocating piston has come into existence efforts have been undertaken to improve the efficiency of the machines .The main drawbacks of reciprocating machines are the considerably large number of moving parts due to the presence of valves , greater inertial loads which reduces dynamic balance and leakage and friction due to the presence of piston rings . The invention urges has reached on Rotary machines .
One main advantage to be gained with a rotary machine is reduction of inertial loads and better dynamic balance. The Wankel rotary engine has been the most successful example to date , but sealing problems contributed to its decline . There , came the ideas of ball piston machines . In the compressor and pump arena, reduction of reciprocating mass in positive displacement machines has always been an objective, and has been achieved most effectively by lobe, gear, sliding vane, liquid ring, and screw compressors and pumps , but at the cost of hardware complexity or higher losses. Lobe, gear, and screw machines have relatively complex rotating element shapes and friction losses. Sliding vane machines have sealing and friction issues . Liquid ring compressors have fluid turbulence losses.
The new design concept of the Ball Piston Engine uses a different approach that has many advantages, including low part count and simplicity of design , very low friction , low heat loss, high power to weight ratio , perfect dynamic balance , and cycle thermodynamic tailoring capability
Diamond is the hardest material known to man kind. When used on tools, diamond grinds away material on micro (Nano) level. Diamond is the hardest substance known and is given a value of 10 in the Mohs hardness scale, devised by the German mineralogist Friedrich Mohs to indicate relative hardness of substances on a rating scale from 1 to 10. Its hardness varies in every diamond with the crystallographic direction. Moreover, hardness on the same face or surface varies with the direction of the cut.
Diamond crystallizes in different forms. Eight and twelve sided crystal forms are most commonly found. Cubical, rounded, and paired crystals are also common. Crystalline diamonds always separate cleanly along planes parallel to the faces. The specific gravity for pure diamond crystals is almost always 3.52. Other properties of the diamond are frequently useful in differentiating between true diamonds and imitations: Because diamonds are excellent conductors of heat, they are cold to the touch; Most diamonds are not good electrical conductors and become charged with positive electricity when rubbed; Diamond is resistant to attack by acids or bases; Transparent diamond crystals heated in oxygen burn at about 1470° F, forming carbon dioxide
The Technique of measuring high temperature is known as pyrometry and the instrument employed is called pyrometer. Pyrometer is specialized type of thermometer used to measure high temperatures in the production and heat treatment of metal and alloys. Ordinary temperatures can be measured by ordinary thermometer, instead pyrometer is employed for measuring higher temperature.
Any metallic surface when heated emits radiation of different wavelengths which are not visible at low temperatures but at about 5400C radiations are in shorter wavelength and are visible to eye and from colour judgement is made as to probable temperature, the colour scale is roughly as follows.
Dark red - 5400C
Red - 7000C
Bright red - 3500C
Orange - 9000C
Yellow - 10100C
White - 12050C and above
The Technique of measuring high temperature is known as pyrometry and the instrument employed is called pyrometer. Pyrometer is specialized type of thermometer used to measure high temperatures in the production and heat treatment of metal and alloys. Ordinary temperatures can be measured by ordinary thermometer, instead pyrometer is employed for measuring higher temperature.
Any metallic surface when heated emits radiation of different wavelengths which are not visible at low temperatures but at about 5400C radiations are in shorter wavelength and are visible to eye and from colour judgement is made as to probable temperature, the colour scale is roughly as follows.
Dark red - 5400C
Red - 7000C
Bright red - 3500C
Orange - 9000C
Yellow - 10100C
White - 12050C and above
When a substance receives heat, change in pressure, electric resistance, radiation, thermoelectric e.m.f and or colour may takeplace. Any of these change can be used for measurement of temperature. Inorder to exercise provision control over the heat treatment and melting operation in the industry temperaturemeasuring device known as pyrometers are used. Also accurate measurement of temperature of Furnaces, molten metals and other heated materials
This seminar will review the state of the art of active control of gas turbine combustors processes. The seminar will first discuss recently developed approaches for active control of detrimental combustion instabilities by use of 'fast' injectors that modulate the fuel injection rate at the frequency of the instability and appropriate phase and gain. Next, the paper discusses two additional approaches for damping of combustion instabilities; i.e., active modification of the combustion process characteristics and open loop modulation of the fuel injection rate at frequencies that differ from the instability frequency. The second part of the seminar will discuss active control of lean blowout in combustors that burn fuel in a lean premixed mode of combustion to reduce NOx emissions. This discussion will describe recent developments of optical and acoustic sensing techniques that employ sophisticated data analysis approaches to detect the presence of lean blowout precursors in the measured data. It will be shown that this approach can be used to determine in advance the onset of lean blowout and that the problem can be prevented by active control of the relative amounts of fuel supplied to the main, premixed, combustion region and a premixed pilot flame. The will close with a discussion of research needs, with emphasis on the integration of utilized active control and health monitoring and prognostication systems into a single combustor control system
This seminar representing the Green engine effect. That is for increasing the efficiency of the engine and avoiding excessive pollution a new method adopting, a ceramic coating [non-metallic solid coating]is done on the parts like piston and crown of the engine used in automobiles
Factors affecting the efficiency
Incomplete combustion
Carbon deposition
Thermal shocking
Pollution control
For avoiding these factors we adopt the method of ceramic coating on the engine Features of ceramic coating We conduct various process in this coating
1. Physical vapour deposition
2. Chemical vapour deposition
3. Ion plating
4. Spattering
5. HAIPAP
Advantages
1. This prevents he deposition of carbon over the cylinder head and piston
2. It acts as a thermal barrier which reduces the amount of heat leakage
3. It help complete combustion of fuels
4. It avoids thermal shocking
5. All the factors above contribute increases the efficiency up to 9% and reduction in pollution in a wide rate
Limitations
1. Additional reactions takes place due to coating.
2. High expense for coating
E85 is an alcohol fuel mixture of 85% ethanol and 15% gasoline, by volume. ethanol derived from crops (bioethanol) is a biofuel.
E85 as a fuel is widely used in Sweden and is becoming increasingly common in the United States, mainly in the Midwest where corn is a major crop and is the primary source material for ethanol fuel production.
E85 is usually used in engines modified to accept higher concentrations of ethanol. Such flexible-fuel engines are designed to run on any mixture of gasoline or ethanol with up to 85% ethanol by volume. The primary differences from non-FFVs is the elimination of bare magnesium, aluminum, and rubber parts in the fuel system, the use of fuel pumps capable of operating with electrically-conductive (ethanol) instead of non-conducting dielectric (gasoline) fuel, specially-coated wear-resistant engine parts, fuel injection control systems having a wider range of pulse widths (for injecting approximately 30% more fuel), the selection of stainless steel fuel lines (sometimes lined with plastic), the selection of stainless steel fuel tanks in place of terne fuel tanks, and, in some cases, the use of acid-neutralizing motor oil. For vehicles with fuel-tank mounted fuel pumps, additional differences to prevent arcing, as well as flame arrestors positioned in the tank's fill pipe, are also sometimes used.
CVCC is a trademark by the Honda Motor Company for a device used to reduce automotive emissions called Compound Vortex Controlled Combustion. This technology allowed Honda's cars to meet the 1970s US Emission requirements without a catalytic converter, and first appeared on the 1975 ED1 engine. It is a form of stratified charge engine.
Honda CVCC engines have normal inlet and exhaust valves, plus a small auxiliary inlet valve which provides a relatively rich air / fuel mixture to a volume near the spark plug. The remaining air / fuel charge, drawn into the cylinder through the main inlet valve is leaner than normal. The volume near the spark plug is contained by a small perforated metal plate. Upon ignition flame fronts emerge from the perforations and ignite the remainder of the air / fuel charge. The remaining engine cycle is as per a standard four stroke engine.
This combination of a rich mixture near the spark plug, and a lean mixture in the cylinder allowed stable running, yet complete combustion of fuel, thus reducing CO (carbon monoxide) and hydrocarbon emissions.
A Diesel Particulate Filter, sometimes called a DPF, is device designed to remove Diesel Particulate Matter or soot from the exhaust gas of a Diesel engine, most of which are rated at 85% efficiency, but often attaining efficiencies of over 90%. A Diesel-powered vehicle with a filter installed will emit no visible smoke from its exhaust pipe.
In addition to collecting the particulate, a method must be designed to get rid of it. Some filters are single use (disposable), while others are designed to burn off the accumulated particulate, either through the use of a catalyst (passive), or through an active technology, such as a fuel burner which heats the filter to soot combustion temperatures, or through engine modifications (the engine is set to run a certain specific way when the filter load reachs a pre-determined level, either to heat the exhaust gasses, or to produce high amounts of No2, which will oxidize the particualte at relatively low temperatures). This procedure is known as 'filter regeneration.' Fuel sulfur interferes many 'Regeneration' strategies, and all jurisdictions that are interested in reduction of particulate emissions, are also passing regulations governing fuel sulfur levels.
A Butterfly valve is a type of flow control device, used to make a fluid start or stop flowing through a section of pipe. The valve is similar in operation to a ball valve. A flat circular plate is positioned in the center of the pipe. The plate has a rod through it connected to a handle on the outside of the valve. Rotating the handle turns the plate either parallel or perpendicular to the flow of water, shutting off the flow. It is a very robust and reliable design. However, unlike the ball valve, the plate does not rotate out of the flow of water, so that a pressure drop is induced in the flow.
There are three types of butterfly valve:
1.Resilient butterfly valve which has a flexible rubber seat. Working pressure up to 1.6 Mpa.
2.High performance butterfly valve which is usually double eccentric in design . Working pressure up to 5.0 Mpa.
3.Tricentric butterfly valve which is usually with metal seated design. Working pressure up to 10.0 Mpa.
Butterfly valves are also commonly utilised in conjunction with carburetors to control the flow of air through the intake manifold and hence the flow of fuel and air into an internal combustion engine. The butterfly valve in this circumstance called a throttle as it is 'throttling' the engines aspiration. It is controlled via a cable or electronics by the furthest right pedal in the drivers footwell (although adaptions for hand control do exist). This is why the accelerator pedal in some countries is called a throttle pedal.
Globe valves are named for their spherical body shape. The two halves of the valve body are separated by a baffle with a disc in the center. Globe valves operate by screw action of the handwheel. They are used for applications requiring throttling and frequent operation. Since the baffle restricts flow, they're not recommended where full, unobstructed flow is required.
A bonnet provides leakproof closure for the valve body. Globe valves may have a screw-in, union, or bolted bonnet. Screw-in bonnet is the simplest bonnet, offering a durable, pressure-tight seal. Union bonnet is suitable for applications requiring frequent inspection or cleaning. It also gives the body added strength. Bolted bonnet is used for larger or higher pressure applications.
Many globe valves have a class rating that corresponds to the pressure specifications of ANSI 16.34. Other different types of valve usually are called globe style valves because of the shape of the body or the way of closure of the disk. As an example typical swing check valves could be called globe type.
The stratified charge engine is a type of internal-combustion engine, similar in some ways to the Diesel cycle, but running on normal gasoline. The name refers to the layering of fuel/air mixture, the charge inside the cylinder.
In a traditional Otto cycle engine the fuel and air are mixed outside the cylinder and are drawn into it during the intake stroke. The air/fuel ratio is kept very close to stoichiometric, which is defined as the exact amount of air necessary for a complete combustion of the fuel. This mixture is easily ignited and burns smoothly.
The problem with this design is that after the combustion process is complete, the resulting exhaust stream contains a considerable amount of free single atoms of oxygen and nitrogen, the result of the heat of combustion splitting the O2 and N2 molecules in the air. These will readily react with each other to create NOx, a pollutant. A catalytic converter in the exhaust system re-combines the NOx back into O2 and N2 in modern vehicles.
A Diesel engine, on the other hand, injects the fuel into the cylinder directly. This has the advantage of avoiding premature spontaneous combustion—a problem known as detonation or ping that plagues Otto cycle engines—and allows the Diesel to run at much higher compression ratios. This leads to a more fuel-efficient engine. That is why they are commonly found in applications where they are being run for long periods of time, such as in trucks.
BlueTec is DaimlerChrysler's name for its two nitrogen oxide (NOx) reducing systems, for use in their Diesel automobile engines. One is a urea catalyst called AdBlue, the other is called DeNOx and uses an oxidising catalytic converter and particular filter combined with other NOx introduced the systems in the reducing systems. Both systems were designed to slash emissions further than ever before. Mercedes-BenzE-Class (using the 'DeNOx' system) and GL-Class (using 'AdBlue') at the 2006 North American International Auto Show as the E 320 and GL 320 Bluetec. This system makes these vehicles 45-state and 50-state legal respectively in the United States, and is expected to meet all emissions regulations through 2009. It also makes DaimlerChrysler the only car manufacturer in the the US committed to selling diesel models in the 2007 model year.
A MAP sensor (manifold absolute pressure) is one of the sensors used in an internal combustion engine's electronic control system. Engines that use a MAP sensor are typically fuel injected. The manifold absolute pressure sensor provides instantaneous pressure information to the engine's electronic control unit (ECU). This is necessary to calculate air density and determine the engine's air mass flow rate, which in turn is used to calculate the appropriate fuel flow. (See stoichiometry.)
An engine control system that uses manifold absolute pressure to calculate air mass, is using the speed-density method. Engine speed (RPM) and air temperature are also necessary to complete the speed-density calculation. Not all fuel injected engines use a MAP sensor to infer mass air flow, some use a MAF sensor (mass air flow).
The Valvetronic system is the first variable valve timing system to offer continuously variable timing (on both intake and exhaust camshafts) along with continuously variable intake valve lift, from ~0 to 10 mm, on the intake camshaft only. Valvetronic-equipped engines are unique in that they rely on the amount of valve lift to throttle the engine rather than a butterfly valve in the intake tract. In other words, in normal driving, the 'gas pedal' controls the Valvetronic hardware rather than the throttle plate
First introduced by BMW on the 316ti compact in 2001, Valvetronic has since been added to many of BMW's engines. The Valvetronic system is coupled with BMW's proven double-VANOS, to further enhance both power and efficiency across the engine speed range. Valvetronic will not be coupled to BMW's N53 and N54, 'High Precision Injection' (gasoline direct injection) technology due to lack of room in the cylinder head.
Cylinder heads with Valvetronic use an extra set of rocker arms, called intermediate arms (lift scaler), positioned between the valve stem and the camshaft. These intermediate arms are able to pivot on a central point, by means of an extra, electronicly actuated camshaft. This movement alone, without any movement of the intake camshaft, can open or close the intake valves.
Because the intake valves now have the ability to move from fully closed to fully open positions, and everywhere in between, the primary means of engine load control is transferred from the throttle plate to the intake valvetrain. By eliminating the throttle plate's 'bottleneck' in the intake track, pumping losses are reduced, fuel economy and responsiveness are improved.
A regenerative brake is an apparatus, a device or system which allows a vehicle to recapture part of the kinetic energy that would otherwise be lost to heat when braking and make use of that power either by storing it for future use or feeding it back into a power system for other vehicles to use.
It is similar to an electromagnetic brake, which generates heat instead of electricity and is unable to completely stop a rotor.
Regenerative brakes are a form of dynamo generator, originally discovered in 1832 by Hippolyte Pixii. The dynamo's rotor slows as the kinetic energy is converted to electrical energy through electromagnetic induction. The dynamo can be used as either generator or brake by converting motion into electricity or be reversed to convert electricity into motion.
Using a dynamo as an regenerative brake was discovered co-incident with the modern electric motor. In 1873, Zénobe Gramme attached the wires from two dynamos together. When one dynamo rotor was turned as a regenerative brake, the other became an electric motor.
It is estimated that regenerative braking systems in vehicles currently reach 31.3% electric generation efficiency, with most of the remaining energy being released as heat; the actual efficiency depends on numerous factors, such as the state of charge of the battery, how many wheels are equipped to use the regenerative braking system, and whether the topology used is parallel or serial in nature. The system is no more efficient than conventional friction brakes, but reduces the use of contact elements like brake pads, which eventually wear out. Traditional friction-based brakes must also be provided to be used when rapid, powerful braking is required.
Hybrid Synergy Drive (HSD) is a set of hybrid car technologies developed by Toyota and used in that company's Prius, Highlander Hybrid, Camry Hybrid, Lexus RX 400h, and Lexus GS 450h automobiles. It combines the characteristics of an electric drive and a continuously variable transmission, using electricity and transistors in place of toothed gears. The Synergy Drive is a drive-by-wire system with no direct mechanical connection between the engine and the engine controls: both the gas pedal and the gearshift lever in an HSD car merely send electrical signals to a control computer.
HSD is a refinement of the original Toyota Hybrid System (THS) used in the 1997–2003 Toyota Prius. As such it is occasionally referred to as THS II. The name was changed in anticipation of its use in vehicles outside the Toyota brand (Lexus).
When required to classify the transmission type of an HSD vehicle (such as in standard specification lists or for regulatory purposes), Toyota describes HSD-equipped vehicles as having E-CVT (Electronically-controlled Continuously Variable Transmission).
FADEC is the acronym for Full Authority Digital Engine Control. It is a system consisting of a digital computer (called EEC /Electronic Engine Control/ or ECU /Electronic Control Unit/) and its related accessories which control all aspects of aircraft engine performance. FADECs have been produced for both piston engines and jet engines, their primary difference due to the different ways of controlling the engines.
Electronics' superior accuracy led to early generation analogue electronic control first used in Concorde's Rolls-Royce Olympus 593 in the 1960s. Later in the 1970s NASA and Pratt and Whitney experimented with the first experimental FADEC, first flown on an F-111 fitted with a highly modified Pratt & Whitney TF-30 left engine. The experiments led to Pratt & Whitney F100 and Pratt & Whitney PW2000 being the first military and civil engines respectively fitted with FADEC and later the Pratt & Whitney PW4000 as the first commercial 'Dual FADEC' engine.
The aircraft's thrust lever sends electrical signals (pilot's command, may also be the autothrottle) to the FADEC. The FADEC digitally calculates and precisely controls the fuel flow rate to the engines giving precise thrust. In addition to the fuel metering function, the FADEC performs numerous other control and monitoring functions such as Variable Stator Vanes (VSV's) and Variable Bleed Valves (VBV's) control, cabin bleeds and power off-takes control, control of starting and re-starting, turbine blade and vane cooling and blade tip clearance control, thrust reversers control, engine health monitoring, oil debris monitoring and vibration monitoring. The inputs come from various aircraft and engine sensors. Apart from the key parameters that are monitored for a safe thrust control (shaft rotational speeds, pressures and temperatures at various points along the gas path) the FADEC also monitors hundreds of various analog, digital and discrete data coming from the engine subsystems and related aircraft systems, providing a fully redundant and fault tolerant engine control.
A mass airflow sensor is used to determine the mass of air entering the engine. The air mass information is necessary to calculate and deliver the correct fuel mass to the engine. Air is a gas, and its density changes as it expands and contracts with temperature and pressure. In automotive applications, air density varies with the vehicle's operating environment, and is an ideal application for a mass sensor. (See stoichiometric, ideal gas law, and density.)
There are two common types of mass airflow sensors in usage on gasoline engines. They are the vane meter and the hot wire. Neither design employs technology that measures air mass directly. However, with an additional sensor or two, the engine's air mass flow rate can be accurately determined.
Both approaches are used almost exclusively on gasoline burning, EFI (electronic fuel injection) engines. Both sensor designs output a 0 - 5.0 volt signal that is proportional to the air mass flow rate, and both sensors have an IAT sensor (intake air temperature) incorporated into their housings.
When a MAF is used in conjunction with an exhaust gas oxygen sensor, the engine's air/fuel ratio can be controlled very accurately. The MAF sensor provides the open-loop predicted air flow information (the measured air flow) to the engine's ECU, and the EGO sensor provides closed-loop feedback in order to make minor corrections to the predicted air mass.
EURO V is the most recent set in a series of mandatory European emission standards applying to new road vehicles sold in the EU. For heavy duty vehicles (lorries) the standards apply to vehicles brought on the market from October 2008. It requires Heavy Goods Vehicles (HGVs) to emit no more than 2.0 g/kWh of NOx and 0.02 g/kWh of PM. As yet, there is no Euro V standard applying for passenger cars, but a recent proposal suggests to limit diesel car emissions to 0.200 g/km of NOx and 0.005 g/km of Particulate Matter (PM), petrol cars to 0.060 g/km NOx and 0.005 g/km PM.
The standards do not mandate the application of specific technologies, but it is widely expected that diesel particulate filters will need to be fitted in diesel vehicles to comply with the PM standard.
Weber carburetors were originally produced in Italy by Edoardo Weber as part of a conversion kit for 1920s Fiats. Weber pioneered the use of twin barrel carburetors with two barrels (or venturi) of different sizes, the smaller one for low speed running and the larger one optimised for high speed use.
In the 1930s Weber began producing twin barrel carburetors for motor racing where two barrels of the same size were used. These were arranged so that each cylinder of the engine has its own carburetor barrel. These carburetors found use in Maserati and Alfa Romeo racing cars.
In time, Weber carburetors were fitted to standard production cars and factory racing applications on automotive marques such as Abarth, Alfa Romeo, Aston Martin, BMW, Ferrari, Fiat, Ford, Lamborghini, Lancia, Lotus, Maserati, Porsche, Triumph, and Volkswagen.
In the United States Weber Carburetors are sold for both street and off road use. They are sold in what is referred to as a Weber Conversion kit. A Weber conversion kit is a complete package of Weber Carburetor, intake manifold or manifold adapter, throttle linkage, air filter and all of the necessary hardware needed to install the Weber on a vehicle.
MegaSquirt is an aftermarket electronic fuel injection (EFI) controller designed to be used with a wide range of internal combustion engines. It is an open project headed by Bruce Bowling and Al Grippo, engineers that work on the U.S. East Coast. The project's do-it-yourself approach makes it the least-expensive system for this purpose. Basic costs are below US$200 as of 2005, although this can vary widely depending on application.
MegaSquirt is a successor of sorts to Bowling and Grippo's earlier EFI332 design, which was more complex yet more powerful system (at least initially). The EFI332 project started around 1995, and culminated in the release of about 200 kits in 2000. The system used a 32-bit MC68332 microcontroller from Motorola, hence the name. A steep learning curve is believed to have prevented the system from gaining wider acceptance.
The two engineers decided to simplify the design and focus on managing the fuel injectors (the EFI332 could also control the spark plug ignition system if so desired). The version 1.0 MegaSquirt used an 8-bit Motorola MC68HC908 microcontroller, but a later MegaSquirt-II upgrade included a 16-bit MC9S12. It is likely that a future version will use a 32-bit processor.
The assembled controller takes input from a few different sensors in order to manage the fuel injectors, including a throttle position sensor (TPS), exhaust gas oxygen sensor (EGO or O2 sensor), MAP sensor, intake air temperature sensor (IAT), and a coolant temperature sensor (CLT). The latter two sensors themselves are usually the General Motors type, although you can recalibrate the controller to use other sensors.
There are several related projects, including:
- MegaJoltLite – an ignition system controller for the Ford Enhanced Distributorless Ignition System (EDIS)
- UltraMegaSquirt – an integrated fuel injection and ignition controller
VTEC (standing for Variable valve Timing and lift Electronic Control) is a system developed by Honda to improve the combustion efficiency of its internal combustion engines throughout the RPM range. This was the first system of its kind and eventually led to different types of variable valve timing and lift control systems that were later designed by other manufacturers (VVTL-i from Toyota, VarioCam Plus from Porsche, and so on). It was invented by Honda's chief engine designer Kenichi Nagahiro.
A ball valve (like the butterfly valve, one of a family of valves called quarter turn valves) is a valve that opens by turning a handle attached to a ball inside the valve. The ball has a hole, or port, through the middle so that when the port is in line with both ends of the valve, flow will occur. When the valve is closed, the hole is perpendicular to the ends of the valve, and flow is blocked. The handle position lets you 'see' the valve's position.
Ball valves are durable and usually work to achieve perfect shutoff even after years of disuse. They are therefore an excellent choice for shutoff applications (and are often preferred to globe valves and gate valves for this purpose). They do not offer the fine control that may be necessary in throttling applications but are sometimes used for this purpose.
The body of ball valves may be made of metal, ceramic, or plastic. The ball may be chrome plated to make it more durable.
There are three general types of ball valves: full port, standard port, and reduced port.
- A full port ball valve has an oversized ball so that the hole in the ball is the same size as the pipeline resulting in lower friction loss. Flow is unrestricted, but the valve is larger.
- A standard port ball valve is usually less expensive, but has a smaller ball and a correspondingly smaller port. Flow through this valve is one pipe size smaller than the valve's pipe size resulting in slightly restricted flow.
- In reduced port ball valves, flow through the valve is two pipe sizes smaller than the valve's pipe size resulting in restricted flow.
A trunnion ball valve has a mechanical means of anchoring the ball at the top and the bottom
Gasoline direct injection or GDI is a variant of fuel injection employed in modern four stroke petrol engines. The gasoline or biobutanol is injected right into the combustion chamber of each cylinder, as opposed to conventional multi point fuel injection that happens in the intake manifold.
GDI enables stratified charge (ultra lean burn) combustion for improved fuel efficiency and emission levels at low load. Further improving efficiency and high-load output-power, the engine power is governed by modulating fuel injection, like a diesel engine; as opposed to restricting intake airflow, like a conventional gas internal combustion engine.
A tyre is a cushion provided with an automobile wheel. It consists of mainly the outer tyre and the inner tube. The air inside the tube carries the entire load and provides the cushion.
The functions of a tyre are
- To support the vehicle load
- To provide cushion against shocks
- To transmit driving and braking forces on the road
- To provide cornering power for smooth steering
Thread Patterns
1. Rib Shape
2. Lug Shape
3. Rib-Lug Shape
4. Block shape
5. Asymmetric Pattern
6. Directional Pattern
Most metal parts are manufactured by either fully-liquid (e.g., casting) or fully-solid (e.g., forging) processes. Semi-Solid Metalworking (SSM) incorporates elements of both casting and forging for the manufacture of near-net-shape discrete parts. Applications are fuel rails, suspension arms, engine brackets, steering Knuckles,rear axle components and motor cycle upper fork plates.
SSM casting was selected for each of these applications for different reasons - high integrity, pressure tightness and design simplification. In each case SSM processing provides several unique advantages over other candidates.
The process capitalises on thixotropy, a physical state wherein a solid material behaves like a fluid when a shear force is applied. The SSM process requires a nondendritic feedstock that can be produced by applying mechanical or electromechanical stirring during alloy solidification at a controlled rate, or from fine-grained materials produced by powder metallurgy or spray forming methods. This feedstock, usually in billet form, is then heated to a temperature between its solidus and liquidus and formed in dies to make near-net-shape parts.
The typical future-tech scenario calls for millions of low-powered radio frequency devices scattered throughout our environment -- from factory-floor sensor arrays to medical implants to smart devices for battlefields.
Because of the short and unpredictable lifespans of chemical batteries, however, regular replacements would be required to keep these devices humming. Fuel cells and solar cells require little maintenance, but the former are too expensive for such modest, low-power applications, and the latter need plenty of sun.
A third option, though, may provide a powerful -- and safe -- alternative. It's called the Direct Energy Conversion (DEC) Cell, a betavoltaics-based 'nuclear' battery that can run for over a decade on the electrons generated by the natural decay of the radioactive isotope tritium. It's developed by researchers at the University of Rochester and a startup, BetaBatt, in a project described in the May 13 issue of Advanced Materials and funded in part by the National Science Foundation.
Because tritium's half-life is 12.3 years (the time in which half of its radioactive energy has been emitted), the DEC Cell could provide a decade's worth of power for many applications. Clearly, that would be an economic boon -- especially for applications in which the replacement of batteries is highly inconvenient, such as in medicine and oil and mining industries, which often place sensors in dangerous or hard-to-reach locations.
'One of our main markets is for remote, very difficult to replace sensors,' says Larry Gadeken, chief inventor and president of BetaBatt. 'You could place this [battery] once and leave it alone.'
Betavoltaic devices use radioisotopes that emit relatively harmless beta particles, rather than more dangerous gamma photons. They've actually been tested in labs for 50 years -- but they generate so little power that a larger commercial role for them has yet to be found. So far, tritium-powered betavoltaics, which require minimal shielding and are unable to penetrate human skin, have been used to light exit signs and glow-in-the-dark watches. A commercial version of the DEC Cell will likely not have enough juice to power a cell phone -- but plenty for a sensor or pacemaker.
The key to making the DEC Cell more viable is increasing the efficiency with which it creates power. In the past, betavoltaics researchers have used a design similar to a solar cell: a flat wafer is coated with a diode material that creates electric current when bombarded by emitted electrons. However, all but the electron particles that shoot down toward the diodes are lost in that design, says University of Rochester professor of electrical and computer engineering Phillipe Fauchet, who developed the more-efficient design based on Gadeken's concept.
The solution was to expose more of the reactive surface to the particles by creating a porous silicon diode wafer sprinkled with one-micron wide, 40 micron-deep pits. When the radioactive gas occupies these pits, it creates the maximum opportunity for harnessing the reaction.
As importantly, the process is easily reproducible and cheap, says Fauchet -- a necessity if the DEC Cell is to be commercially viable.
The fabrication techniques may be affordable, but the tritium itself -- a byproduct of nuclear power production -- is still more expensive than the lithium in your cell-phone battery. The cost is less of an issue, however, for devices designed specifically to collect hard-to-get data.
Cost is only one reason why Gadeken says he will not pursue the battery-hungry consumer electronics market. Other issues include the regulatory and marketing obstacles posed by powering mass-market devices with radioactive materials and the large battery size that would be required to generate sufficient power. Still, he says, the technology might some day be used as a trickle-recharging device for lithium-ion batteries.
Instead, his company is targeting market sectors that need long-term battery power and have a comfortable familiarity with nuclear materials.
'We're targeting applications such as medical technology, which are already using radioactivity,' says Gadeken.
For instance, many implant patients continue to outlive their batteries and require costly and risky replacement surgery.
Eventually, Gadeken hopes to serve NASA as well, if the company can find a way to extract enough energy from tritium to power a space-faring object. Space agencies are interested in safer and lighter power sources than the plutonium-powered Radioisotope Thermal Generators (RTG) used in robotic missions, such as Voyager, which has an RTG power source that is intended to run until around 2020.
Furthermore, a betavoltaics power source would likely alleviate environmental concerns, such as those voiced at the launch of the Cassini satellite mission to Saturn, when protestors feared that an explosion might lead to fallout over Florida.
For now, though, Gadeken hopes to interest the medical field and a variety of niche markets in sub-sea, sub-surface, and polar sensor applications, with a focus on the oil industry.
And the next step is to adapt the technology for use in very tiny batteries that could power micro-electro-mechanical Systems (MEMS) devices, such as those used in optical switches or the free-floating 'smart dust' sensors being developed by the military.
In fact, another betavoltaics device, under development at Cornell University, is also targeting the MEMS power market. The Radioisotope-Powered Piezoelectric Generator, due in prototype form in a few years, will combine a betavoltaics cell with a tritium-powered electromechanical cantilever device first demonstrated in 2002.
Amit Lal, one of the Cornell researchers, offers both praise and cautious skepticism about the DEC Cell. While he's impressed with the power output from the DEC Cell, he said that there are still issues with power leakage. To avoid those potential leakage problems, Cornell is using a slightly larger-scale wafer design. They're also planning to move to a porous design and either solid or liquid tritium to improve efficiency.
Lal also notes that the market for either Cornell's device or the DEC Cell might be squeezed by newer, longer-lasting lithium batteries. Still, there's a niche for very small devices, he believes, especially those that must run longer than ten years.
The future of fuel-cell vehicles is already happening in an unlikely proving ground: forklifts used in warehouses. Several manufacturers are testing forklifts powered by a combination of fuel cells and batteries -- and finding that these hybrids perform far better than the lead-acid battery systems now typically used. In some situations, in fact, they could pay for themselves in cost savings and added productivity within two or three years.
The adoption of the technology points to a promising hybrid strategy for finally making fuel cells economically practical for all sorts of vehicles. While researchers have speculated for years that hydrogen fuel cells could power clean, electric vehicles, cutting emissions and decreasing our dependence on oil, manufacturing fuel cells big enough to power a car is prohibitively expensive -- one of the main reasons they are not yet in widespread use. But by relying on batteries or ultracapacitors to deliver peak power loads, such as for acceleration, fuel cells can be sized as much as four times smaller, slashing manufacturing costs and helping to bring fuel cell-powered vehicles to market.
The forklift hybrids use ultracapacitors, devices similar to batteries but able to deliver higher bursts of power. The fuel cell powers the forklift as it drives through a warehouse, while at the same time the cell charges the ultracapacitors. The ultracapacitors kick in to lift a pallet.
'If you had to do that with just fuel-cell power, you'd need a fuel cell about four times as large, which would be too big,' says Michael Sund, spokesperson for Maxwell Technologies, an ultracapacitor manufacturer. 'It would dwarf the forklift, and it would also be very expensive. Being able to downsize the fuel cell makes it smaller, lighter, and cheaper.'
The use of the fuel-cell hybrids in forklifts could bode well for the auto industry. Cars and SUVs, like forklifts, have peak power demands. When cruising, they use less than one-quarter of an engine's maximum power, which is sized to provide acceleration and sustained power up long hills, says Brian Wicke, who's developing fuel-cell systems at GM.
Batteries and ultracapacitors could provide at least some of the accelerating power, allowing the fuel cell to be smaller. Last year, GM rolled out a concept car featuring a hybrid system, although it will be after the end of the decade before such a vehicle is available. Other major automakers are also pursuing the hybrid technology.
In addition to supplying peak power, ultracapacitors and batteries give fuel-cell vehicles the ability to recapture energy from braking, as happens now with commercial gasoline-battery hybrid vehicles. This can make the system much more efficient, especially in applications such as city driving. A vehicle powered by a fuel cell alone would not have this ability.
'You can't take energy into a fuel cell. You've got to have a battery,' says Brian Barnett at Tiax in Cambridge, MA, a company that has provided analyses of fuel cells for the U.S. Department of Energy. 'Why you would put an electric drive train system on the road, and not have the ability to accept regenerative braking is beyond me.'
The future of fuel-cell vehicles is already happening in an unlikely proving ground: forklifts used in warehouses. Several manufacturers are testing forklifts powered by a combination of fuel cells and batteries -- and finding that these hybrids perform far better than the lead-acid battery systems now typically used. In some situations, in fact, they could pay for themselves in cost savings and added productivity within two or three years.
The adoption of the technology points to a promising hybrid strategy for finally making fuel cells economically practical for all sorts of vehicles. While researchers have speculated for years that hydrogen fuel cells could power clean, electric vehicles, cutting emissions and decreasing our dependence on oil, manufacturing fuel cells big enough to power a car is prohibitively expensive -- one of the main reasons they are not yet in widespread use. But by relying on batteries or ultracapacitors to deliver peak power loads, such as for acceleration, fuel cells can be sized as much as four times smaller, slashing manufacturing costs and helping to bring fuel cell-powered vehicles to market.
The forklift hybrids use ultracapacitors, devices similar to batteries but able to deliver higher bursts of power. The fuel cell powers the forklift as it drives through a warehouse, while at the same time the cell charges the ultracapacitors. The ultracapacitors kick in to lift a pallet.
'If you had to do that with just fuel-cell power, you'd need a fuel cell about four times as large, which would be too big,' says Michael Sund, spokesperson for Maxwell Technologies, an ultracapacitor manufacturer. 'It would dwarf the forklift, and it would also be very expensive. Being able to downsize the fuel cell makes it smaller, lighter, and cheaper.'
The use of the fuel-cell hybrids in forklifts could bode well for the auto industry. Cars and SUVs, like forklifts, have peak power demands. When cruising, they use less than one-quarter of an engine's maximum power, which is sized to provide acceleration and sustained power up long hills, says Brian Wicke, who's developing fuel-cell systems at GM.
In addition to supplying peak power, ultracapacitors and batteries give fuel-cell vehicles the ability to recapture energy from braking, as happens now with commercial gasoline-battery hybrid vehicles. This can make the system much more efficient, especially in applications such as city driving. A vehicle powered by a fuel cell alone would not have this ability.
'You can't take energy into a fuel cell. You've got to have a battery,' says Brian Barnett at Tiax in Cambridge, MA, a company that has provided analyses of fuel cells for the U.S. Department of Energy. 'Why you would put an electric drive train system on the road, and not have the ability to accept regenerative braking is beyond me.'
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