Latest trend in Automotive technology, Exams of Engineering

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LATEST TRENDS : AUTOMOTIVE

TECHNOLOGY

INTRODUCTION

1. For a long time the development of automotive technology in our country

was almost non-existent. There were just a couple of models of commercial

vehicles that were seen on Indian roads and every Indian used to look at

imported cars with wonder and wish that these cars were available in our

country. Then came a revolution with the introduction of a range of cars

manufactured in collaboration with foreign companies. There was no looking

back as more and more vehicles were introduced and technology took leaps

and bound to the extent that India has now been able to manufacture

indigenously made vehicles and even export them.

2. With the introduction of computerized chips, there has been a radical

change in automotive technology. To keep abreast with these changes it is

important for us to not only be aware of the existing technology but also with

the future trends and developments in automotives which are taking place all

over the world.

3. There have been major breakthroughs that have been made in engine

technology. Today we have small compact engine having greater power

output and minimum emissions. The emphasis is also towards lesser fuel

consumption with the ever increase in fuel prices and depleting oil resources.

There is also a trend towards development of alternate fuel and electric

engines. Already CNG and LPG are being used in our country and an

indigenously made electric car Reva is being introduced. Similarly there has

been considerable progress made in fuel injection, transmission, suspension,

steering and almost every other automotive aspect of vehicles.

4. This presentation is going to broadly cover all aspect of automotive

technology that are being developed and also those in conceptual stages and

likely to be seen on the road in the near future. Already a no of vehicles like

the Mercedes S class model have introduced state of art technology and they

are available in our country too. This paper has been written with the aim of

keeping abreast everyone's knowledge of the technology behind the modern

vehicles and also the vehicles of tomorrow.

through the vane transfer pump, which is screwed on to the end of rotor. This increases the fuel pressure according to the speed of the rotor. The fuel then flows along a passage in the hydraulic head and around the annular groove to the metering valve. From here it flows to the metering port, where it enters the rotor.

7. Advantages of Distributor Pump :- (a) Low weight (b) Small size (c) Higher fuel economy (d) Adequate cooling (e) Less rust formation Fig : Common Rail Injector Systems

Electric Vehs

8. Electronic Diesel Control Replaces Mechanical Governor in the FIP The development of EDC (Electronic Diesel Control) Fuel injection system is like that of MPFI (Multi Point Fuel Injection System) in petrol vehs. The essential difference between the conventional injection pump and the one that is subject to electronic is given below: - (a) The elimination of a mechanical governor, its place on the pump camshaft being taken by an impulse disc that rotates about a stationary speed sensor. (b) The provision of a linear solenoid actuator, which constantly adjusts the position of a spring return control rod for the pumping elements. (c) The addition of a sensor that detects the changing position of the pump control rod
9. The electronic control unit receives signals from various sensors, this information is processed and compared with pre-programmed values, so that the appropriate command can be sent to control rod actuator and the required quantity of fuel is delivered to the injectors. Fig : Common Rail and High Pressure Pump
10. Schematic Arrangement of an EDC System for a Heavy Veh (a) Amount of Acceleration The Accelerator pedal is connected to a sensor that converts pedal travel into electronic signal. Hence, there is no need for a mechanical connection between pedal and fuel injection pump. (b) Change in Air Pressure This information is required so that the quantity of fuel delivered to the injector can be accurately matched to the available amount of air.

14. A fuel cell provides a DC (direct current) voltage that can be used to power motors, lights or any number of electrical appliances. There are several different types of fuel cells, each using a different chemistry. The type of electrolyte they use usually classifies fuel cells. Some types of fuel cells show promise for use in power generation plants. Others may be useful for small portable applications or for powering cars. The proton exchange membrane fuel cell (PEMFC) is one of the most promising technologies. This is the type of fuel cell that will end up powering cars, buses and maybe even our houses. The proton exchange membrane fuel cell ( PEMFC ) uses one of the simplest reactions of any fuel cell. In the figure above there are four basic elements of a PEMFC.:
15. The anode, the negative post of the fuel cell, has several jobs. It conducts the electrons that are freed from the hydrogen molecules so that they can be used in an external circuit. It has channels etched into it that disperse the hydrogen gas equally over the surface of the catalyst. The cathode, the positive post of the fuel cell, has channels etched into it that distribute the oxygen to the surface of

the catalyst. It also conducts the electrons back from the external circuit to the catalyst, where they can recombine with the hydrogen ions and oxygen to form water. The electrolyte is the proton exchange membrane. This specially treated material, which looks something like ordinary kitchen plastic wrap, only conducts positively charged ions. The membrane blocks electrons. The catalyst is a special material that facilitates the reaction of oxygen and hydrogen. It is usually made of platinum powder very thinly coated onto carbon paper or cloth. The catalyst is rough and porous so that the maximum surface area of the platinum can be exposed to the hydrogen or oxygen. The platinum-coated side of the catalyst faces the PEM.

16. The pressurized hydrogen gas (H 2 ) entering the fuel cell on the anode side. This gas is forced through the catalyst by the pressure. When an H (^2) molecule comes in contact with the platinum on the catalyst, it splits into two H+^ ions and two electrons (e_). The electrons are conducted through the anode, where they make their way through the external circuit (doing useful work such as turning a motor) and return to the cathode side of the fuel cell. Meanwhile, on the cathode side of the fuel cell, oxygen gas (O 2 ) is being forced through the catalyst, where it forms two oxygen atoms. Each of these atoms has a strong negative charge. This negative charge attracts the two H+^ ions through the membrane, where they combine with an oxygen atom and two of the electrons from the external circuit to form a water molecule (H 2 O). This reaction in a single fuel cell produces only about 0.7 volts.
17. The oxygen required for a fuel cell comes from the air. In fact, in the PEM fuel cell, ordinary air is pumped into the cathode. The hydrogen is not so readily available, however. Hydrogen has some limitations that make it impractical for use in most applications. For instance, you don't have a hydrogen pipeline coming to your house, and you can't pull up to a hydrogen pump at your local gas station.
18. Hydrogen is difficult to store and distribute, so it would be much more convenient if fuel cells could use fuels that are more readily available. A device

23. Some advantages and disadvantages of a parallel configuration include; (a) Increased performance over ICE alone as it optimizes operating efficiency by choosing the best power source for the speed/torque requirement. (b) Most parallel vehicles do not need a generator to produce electrical energy for the storage unit as an ICE standard alternator can be used. (c) The power is directly coupled to the road, thus it can be more efficient. (d) Full size ICE and transmission produce no weight or space savings. This concept offers no improvement with respect to overall maintenance of the vehicle.
24. Series Hybrid By contrast, in a series hybrid (Figure below) the gasoline engine turns a generator, and the generator can either charge the batteries or power an electric motor that drives the transmission. Thus, the gasoline engine never directly powers the vehicle.
25. Schematic Diagram of Series System.
26. The advantages and disadvantages of a series configuration include: (a) The engine never idles, which reduces vehicle emissions.

(b) The engine drives a generator to run at optimum performance therefore achieving better fuel economy. (c) Allows a variety of options when mounting the engine and vehicle components. (d) Some series hybrids do not need a transmission; (e) The engine is used to generate energy for the supply of electrical power to the storage unit (batteries) and thus, can remain fairly small in comparison to an engine used in the parallel mode.

27. Components Of A Hybrid Vehicle. (a) The Power Unit Hybrid Electric Vehicles (HEVs) rely on power from both a heat engine and an electric motor to provide the torque to move the vehicle. In a hybrid vehicle, the heat engine, also called the hybrid power unit (HPU), performs different functions than its conventional counterpart. In a parallel hybrid vehicle, the HPU drives the wheels through a transaxle; in a series hybrid vehicle, it drives an alternator to produce electricity. In the HEV, the electric motor assumes some of the power responsibilities of the HPU, thereby permitting the use of a smaller and more efficient engine. However, in order to achieve high fuel economy , the HEV configuration places additional demands on the HPU and requires more critical packaging and integration constraints. Specifically, the HPU must be able to start and stop much more quickly and the emissions during starts must be lower. The candidates for the HPU are the gasoline engine / diesel engines, gas turbine. The ability to achieve specific power and power density equal to or higher than that of conventional engines is also an important factor. Other considerations include noise and vibration reduction, reliability, durability, maintenance, operating costs, and safety. (b) The Storage Device. High-power battery technologies are the principal energy storage devices that are being considered for application with Hybrid Electric Vehicles (HEVs). Other technologies, such as ultra capacitors and flywheels, are also promising. Two candidate battery chemistries have been identified as the most likely to succeed in meeting the HEV high-power requirements: nickel/metal hydride and lithium-ion. Nickel/metal hydride batteries are currently used in electric vehicles, Computers, medical equipment, and other applications. They offer relatively good power capability as a result of the good ionic conductivity of the potassium hydroxide electrolyte, and their components are recyclable. The main challenges are their high cost, the need to control hydrogen loss, and their low cell efficiency. Lithium-ion batteries offer excellent energy density that can be traded for higher power. They are being investigated for use in HEVs in full-size modules in a two-phase program to scale-up the basic performance and life capabilities demonstrated in small laboratory cells

Overrunning clutches #4& Control the connections between the electric motors and the system.

29. Power flows from the internal combustion engine, through the secondary drive shaft to the transmission. It then flows from the transmission to the primary drive shaft, and then to the wheels. Overrunning clutches 3, 2 are engaged and all others are disengaged.
30. Power flows from the internal combustion engine, through the secondary drive shaft, through the transmission, and then to the primary drive shaft and then to the tires. Power also flows from both electric motors, to the transmission, and then to the primary drives shaft and the tires. Overrunning clutches 3, 4, and 5 are engaged and solenoid clutch 2 is engaged. All others are disengaged. (a) Power flows from the wheels to the primary drive shaft, then through the transmission, through the secondary drive shaft, and to the generator, and finally to the batteries. This occurs during regenerative braking. Solenoid clutches 1 and 2 are engaged, all other clutches are disengaged. (b) Power flows from the internal combustion engine, through drive shaft 2, to the transmission, and then to drive shaft 1 and the tyres. Power also flows from the I.C.E., through drive shaft 2, and to the generator. Overrunning clutch 3 and solenoid clutch 1 are engaged, all others are disengaged. (c) Power flows from the internal combustion engine, through the secondary drive shaft, to the transmission, then through the primary drive shaft and the tires. The I.C.E. also provides power to the generator, through solenoid clutch 1, and then to the batteries. Also, the electric motors provide power to the primary drive shaft, through the transmission. All clutches are engaged.

TRANSMISSION

Automatic Transmission

1. Unlike a semi-automatic transmission sys a fully automatic one completely relives the drive of the duty of changing gear. While still allowing the drive to override its normal operation if though desirable An automatic transmission has therefore been defined by the socially of automotive engineers in America as a transmission in which ratio changes are effected automatically without manual assist: the individual roles played by the fluid coupling converter and epicyclical gear train the development of automatic transmission. However it was not until the rate 1930’s when a brilliant team of general motors train mission engineers led by eart Thompson added a sophisticated hydraulic control sys to the operation of an epicycle gear train that the fully automatic transmission became a practical reality.
2. Advantage of Automatic Transmission (a) It minimizes drivers fatigue especially in heavy traffic by eliminating the need to operate a clutch pedal and gear lever for starting from rest and changing gear. (b) It contributes to safer driving because the concentration of the drive is not disturbed by the need to change gear. Also both hands can remain on the steering wheel. (c) Progress can be smoother under normal driving conditions because gear changes will occur at the theoretically correct moment in terms of road speed and throttle opening.

Fig : Hydraulic Power Steering

5. Electronic Variable Orifice Steering. The Electronic variable orifice (EVO) steering system is standard on many late-model vehicles. The EVO steering system provides high power steering assistance during low speed cornering and parking, and normal power steering assistance at higher speeds for proper road feel. Higher power steering assistance during low speed cornering and parking increases driver convenience.
6. The steering wheel rotation sensor is mounted on the steering column, and a shutter disc attached to the steering shaft rotates through the sensor when the steering wheel is rotated. A row of slits is positioned near the outer edge of the shutter disc. When these slits rotate through the sensor, a steering wheel rotation speed signal is sent from the sensor to the control module.
7. The vehicle speed sensor (VSS) is mounted in the transaxle or transmission, and this sensor sends a signal to the control module in relation to vehicle speed. The VSS signal is also used for other purposes.
8. EVO Output Control. A varying current flow is sent from the control module through the EVO actuator in the power steering pump. The actuator swivels freely when it is installed in the power steering pump. As the control module changes the current flow through the actuator, the actuator supplies a variable pressure to the spool valve in the power steering pump. Two wires are connected from the actuator to the control module. The power steering pump is mounted directly to the engine to reduce noise, vibration, and harshness (NVH).

9. The control module positions the actuator and spool valve to provide full power steering assistance under these conditions: (a) Vehicle speed less than 10 mph (16 kmph). (b) Steering wheel rotation above 15 rpm
10. The full power assist mode reduces driver effort required to turn the steering wheel during low speed cornering and parking for increased convenience. In the full power – assist mode, the control module supplies 30 milliamps (ma) to the actuator. The control module positions the actuator and spool valve to reduce power steering assistance under these conditions: (a) Vehicle speed above 25 mph (40 kmph) (b) Steering wheel rotation below 15 rpm. Electrical Power Assisted Steering
11. Electrical Power Assisted Steering (EPAS) basically comprises a system that uses electronic control and an electrical power supply as distinct from the mechanical control and hydraulic power supply long associated with conventional power assisted steering system. Electrical Power Assisted steering system was first used by the Suzuki motor Company in Japan for their small three cylinder engine, front wheel drive, city cars in 1988 and they were followed soon after by other major car manufactures of the world.
12. Advantages of Electrical Power Assisted Steering : - (a) Fuel economy is improved, because to all intents and purposes, the system only consumes energy when there is a demand for power assistance. There is no requirement for a hydraulic pump to be continuously driven by the engine. (b) A more compact installation can be achieved for the system by virtue of its integrated construction; hence there is less intrusion on engine compartment space. (c) A significant saving in weight is generally attributed to electrical power assisted systems, which again derives from their integrated construction and few components. (d) Similar to hydraulic power assistance, the various systems can be provided with speed sensitive characteristics and naturally have a fail – safe facility. (e) In some system, power assistance is still available even though the engine is not running. While in others this is intentionally prevented to avoid discharging the battery. (f) The service nuisance of dealing with fluid leaks is non-existent.

14. Electronic Power Steering Operation. An Electronic power steering (EPS) system is used in Acura NSX models. The EPS system has a rack and pinion steering gear with electric steering assist. The rack and pinion steering gear changes rotary steering wheel motion to transverse motion of the rack. The motor that provides electric steering assist is designed in to the steering gear. The steering sensor is mounted in the pinion shaft. This sensor sends input voltage signals to the EPS control unit in relation to the direction, amount, and torque of the steering wheel rotation.
15. The EPS control unit is mounted above the steering gear. This control unit receives voltage input signals from the steering sensors, VSS, or differential speed sensor. When these signals are received, the EPS control unit calculates the proper amount and direction of steering assist. The EPS control unit then commands a power module in the EPS control unit to drive the electric motor in the steering gear and provide the proper direction and amount of steering assist. The EPS control unit also contains self – diagnostic capabilities. Four Wheel Steering System
16. Overview. The concept of steering more than four wheels in case of multi axles veh even though, exists, indigenous development of technology in this regard has not yet taken place. Certain military applications, like bridging role needs development of unusually long vehs in which more than four wheels (four in the front and four in the rear) have to be steered to make the veh maneuverable on high ways. Fig : 4 Wheel Steering
17. Keeping the above application in view technology involving electronically cont hydrostatic steering has been developed to steer more than four wheels of long mobile platform. There is a necessity to design and devp the multi wheel steering system for multi wheel extra long transporters. These will subsequently be utilized for mil applications like bridge laying role to tpt unusually extra long eqpt. Hence the analysis design and development of multi wheel steering system for extra long transporter has been taken up by VRDE, Ahmednagar, for towing Agni Msl Tlrs. The extra long tpts with 15 m long shall be provided with six axles out of which four axles would be steerable i,e. Two axles each in front and rear are steer able and 3rd^ and 4th axles are tandem non steerable.

18. 4 WS Characteristics If a car with conventional front wheel steering is parallel parked at a curb between two vehicles, this car may be driven from the parking space with out hitting the car in front if the front wheels are turned all the way to the left. Fig : 4WS Low Speed Control
19. When the car in the same parking space as a 4WS system that steers the rear wheels in the opposite direction to the front wheels at low speed, the car steers out of the parking space with plenty of distance between the vehicle parked in front. When the rear wheels steering the opposite direction to the front wheels, the rear wheels steer toward the curb. This action causes the right rear tyre to strike the curb if the car is parked closed to the curb. Therefore, the maximum rear steering angle must be considerably less than the maximum front wheel steering angle to help prevent this problem. However a car with 4 WS has a smaller turning circle or turning radius compared to a vehicle with conventional front wheel steering. This improves maneuverability while parking.
20. 4 WS Control. The rear wheel steering in a 4WS system may be controlled in relation to vehicle speed or the amount of steering wheel rotation. At low vehicle speeds or with a considerable amount of steering wheel rotation, the rear wheels are steered in the opposite direction to the front wheels. When the vehicle is operating at higher speeds or with a small amount of steering wheel rotation, the rear wheels are steered in the same direction as the front wheels.
21. When a vehicle is cornering at higher speeds, centrifugal force tends to move the rear of the vehicle sideways. This action causes the rear tyres to slip sideways