single cylinder gasoline engine

How airbags work

The design is conceptually simple; a central "Airbag control unit" (ACU) (a specific type of ecu) monitors a number of related sensors within the vehicle, including accelerometers, impact sensors, side (door) pressure sensors, wheel speed sensors, gyroscopes, brake pressure sensors and seat occupancy sensors. The bag itself and its inflation mechanism is concealed within the steering wheel boss (for the driver), or the dashboard (for the front passenger), behind plastic flaps or doors which are designed to "tear open" under the force of the bag inflating. Once the requisite 'threshold' has been reached or exceeded, the airbag control unit will trigger the ignition of a gas generator propellant to rapidly inflate a fabric bag. As the vehicle occupant collides with and squeezes the bag, the gas escapes in a controlled manner through small vent holes. The airbag's volume and the size of the vents in the bag are tailored to each vehicle type, to spread out the deceleration of (and thus force experienced by) the occupant over time and over the occupant's body, compared to a seat belt alone.

The signals from the various sensors are fed into the Airbag control unit, which determines from them the angle of impact, the severity, or force of the crash, along with other variables. Depending on the result of these calculations, the ACU may also deploy various additional restraint devices, such as seat belt pre-tensioners, and/or airbags (including frontal bags for driver and front passenger, along with seat-mounted side bags, and "curtain" airbags which cover the side glass). Each restraint device is typically activated with one or more pyrotechnic devices, commonly called an initiator or electric match. The electric match, which consists of an electrical conductor wrapped in a combustible material, activates with a current pulse between 1 to 3 amperes in less than 2 milliseconds. When the conductor becomes hot enough, it ignites the combustible material, which initiates the gas generator. In a seat belt pre-tensioner, this hot gas is used to drive a piston that pulls the slack out of the seat belt. In an airbag, the initiator is used to ignite solid propellant inside the airbag inflator. The burning propellant generates inert gas which rapidly inflates the airbag in approximately 20 to 30 milliseconds. An airbag must inflate quickly in order to be fully inflated by the time the forward-traveling occupant reaches its outer surface. Typically, the decision to deploy an airbag in a frontal crash is made within 15 to 30 milliseconds after the onset of the crash, and both the driver and passenger airbags are fully inflated within approximately 60-80 milliseconds after the first moment of vehicle contact. If an airbag deploys too late or too slowly, the risk of occupant injury from contact with the inflating airbag may increase. Since more distance typically exists between the passenger and the instrument panel, the passenger airbag is larger and requires more gas to fill it.

Older airbag systems contained a mixture of sodium azide (NaN₃), KNO₃, and SiO₂. A typical driver-side airbag contains approximately 50-80 g of NaN₃, with the larger passenger-side airbag containing about 250 g. Within about 40 milliseconds of impact, all these components react in three separate reactions that produce nitrogen gas. The reactions, in order, are as follows.

(1) 2 NaN₃ → 2 Na + 3 N₂ (g)

(2) 10 Na + 2 KNO₃ → K₂O + 5 Na₂O + N₂ (g)

(3) K₂O + Na₂O + 2 SiO₂ → K₂O₃Si + Na₂O₃Si (silicate glass)

The first reaction is the decomposition of NaN₃ under high temperature conditions using an electric impulse. This impulse generates to 300 °C temperatures required for the decomposition of the NaN₃ which produces Na metal and N₂ gas. Since Na metal is highly reactive, the KNO₃ and SiO₂ react and remove it, in turn producing more N₂ gas. The second reaction shows just that. The reason that KNO₃ is used rather than something like NaNO₃ is because it is less hygroscopic. It is very important that the materials used in this reaction are not hygroscopic because absorbed moisture can de-sensitize the system and cause the reaction to fail. The final reaction is used to eliminate the K₂O and Na₂O produced in the previous reactions because the first-period metal oxides are highly reactive. These products react with SiO₂ to produce a silicate glass which is a harmless and stable compound.

According to a patent, the particle size of the sodium azide, potassium nitrate, and silicon dioxide are important. The NaN₃ and KNO₃ must be between 10 and 20 , while the SiO₂ must be between 5 and 10 µm.

There has been a recent effort to find alternative compounds that can be used in airbags which have less toxic byproducts. In a journal article by Akiyoshi et. Al., it was found that for the reaction of the Sr complex nitrate, (Sr(NH₂NHCONHNH₂)∙(NO₃)₂ of carbohydrazide (SrCDH) with various oxidizing agents resulted in the evolution of N₂ and CO₂ gases. Using KBrO₃ as the oxidizing agent resulted in the most vigorous reaction as well as the lowest initial temperature of reaction. The N₂ and CO₂ gases evolved made up 99% of all gases evolved. Nearly all the starting materials won’t decompose until reaching temperatures of 500 °C or higher so this could be a viable option as an air bag gas generator. In a patent containing another plausible alternative to NaN₃ driven airbags, the gas generating materials involved the use of guanidine nitrate 5-amino tetrazole, bitetrazole dehydrate,  nitroimidazole, and basic copper nitrate. It was found that these non-azide reagents allowed for a less toxic, lower combustion temperature reaction and more easily disposable air bag inflation system.

Front airbags normally do not protect the occupants during side, rear, or rollover accidents. Since airbags deploy only once and deflate quickly after the initial impact, they will not be beneficial during a subsequent collision. Safety belts help reduce the risk of injury in many types of crashes. They help to properly position occupants to maximize the airbag's benefits and they help restrain occupants during the initial and any following collisions.

In vehicles equipped with a rollover sensing system, accelerometers and gyroscopes are used to sense the onset of a rollover event. If a rollover event is determined to be imminent, side curtain airbags are deployed to help protect the occupant from contact with the side of the vehicle interior, and also to help prevent occupant ejection as the vehicle rolls over.

HAPPY ONAM............

Duster face-lift revealed at Frankfurt Motor Show

Dacia showcased the new 2014 model of its successful Duster SUV at the 2013 Frankfurt Motor Show. As can be seen from the image, the updated Duster features cosmetic changes to the front including a new grille featuring a double chrome strip design at the top coupled with a mesh air intake below and new double-optic headlights with daytime running lights. Other changes comprise new 16-inch dark metal alloy wheels, slightly altered tail light design, a chrome plated exhaust pipe and Duster branded roof rails. 

On the inside, the 2014 Dacia Duster is loaded with more equipment such as the new Dacia Media Nav multimedia system including Bluetooth and cruise control/speed limiter (depending on the model). Other new features are rear parking assist and Electronic Stability Control (ESC) fitted as standard on Euro 5 versions. Dacia is also offering a host of optional equipment for the Duster in European markets.

The 1.5 litre dCi diesel engine and the 1.2 litre direct-injection turbocharged petrol engine as well as the 1.6 litre petrol engine all remain unchanged for the new Dacia Duster

duster specificaion

Dimensions & Weight
Length	4315 mm
Width	1822 mm
Height	1695 mm
Wheelbase	2673 mm
Ground Clearance	205 mm

Capacity
Seating Capacity	5 Person
Doors	5 Doors
No of Seating Rows	2 Rows
Bootspace	475 litres
Fuel Tank Capacity	50 litres

Engine & Transmission
Engine Type	1.5 dCI K(K THP Diesel engine
Displacement	1461 cc
Fuel Type	Diesel
Max Power	108 bhp @ 3900 RPM
Max Torque	248 Nm @ 2250 RPM
Mileage (ARAI)	19.01 kmpl
Alternate Fuel	Not Applicable
Valve/Cylinder (Configuration)	4, DOHC
Cylinders	4, Inline
Transmission Type	Manual
No of gears	6 Gears
Dual Clutch	0
Sport Mode	0
Drivetrain	FWD

Suspensions, Brakes, Steering & Tyres
Suspension Front	Independent MacPherson strut with coil springs & anti-roll bar
Suspension Rear	Torsion beam axle with coil springs & anti-roll bar
Front Brake Type	Disc
Rear Brake Type	Drum
Steering Type	hydraulic power assisted
Minimum Turning Radius	5.2 metres
Front Tyres	215 / 65 R16
Rear Tyres	215 / 65 R16 Safety Airbags 2 (Driver & Co-Driver) Dual-Stage Airbags No Middle rear three-point seatbelt No Braking & Traction Anti-Lock Braking System Yes Electronic Brake-force Distribution Yes Brake Assist Yes Electronic Stability Program No Traction Control System No Locks & Security Engine immobilizer Yes Central Locking Remote Child Safety Lock Yes Comfort & Convenience Cruise Control No Air Conditioner Manual Rear AC Separate Zone Heater Yes Power Steering Yes Steering Adjustment Tilt Ash Tray No Keyless Start Yes CD Changer No Headlight off and lgnition Key Off Reminder Yes Paddle Shift No Rear Parking Sensors Yes Vanity Mirrors on Sun Visors Co-Driver Only Cigarette Lighter No 12V Power Outlets Yes Seats & Upholstery Seat Upholstery Fabric Active headrest No Driver Height Adjustable Seat Yes Lumbar Support Driver Only Folding Rear Seat Full Driver Armrest No Rear Armrest With Cup Holder Head-rests Front & Rear Adjustable Head-rests Front & Rear Leather-wrapped Steering Wheel No Front Seat Pockets Yes Audio Controls in Rear Armrest No Storage Cup Holders Front & Rear Doors, Windows, Mirrors & Wipers Power Windows Front & Rear Rear Defogger Yes Boot-lid Opener Internal with Remote Door Pockets Front Outside Rear View Mirrors Both Sides Adjustable ORVM Electrically Adjustable Turn Indicators on ORVM No Body-Coloured ORVMs No Rear Wiper Yes Rain-sensing Wipers No Headlight Washers No Exterior Sunroof / Moonroof No Body-Coloured Bumpers Yes Roof Mounted Antenna Yes Lighting Headlamps Conventional Automatic Head Lamps No Fog Lamps Front Clear lens Head Lamp Yes Daytime Running Lamps No LED tail lamps No Clear lens Tail Lamp Yes Headlight Height Adjuster Yes Instrumentation Distance to Empty Yes Average Fuel Consumption Yes Average Speed Yes Clock Digital Seat Belt Warning Yes Low Fuel Level Warning Yes Door Ajar Warning Yes Entertainment, Information & Communication Music Player Size 2 Din Integrated (in-dash) Music System Yes Touch-screen Display No GPS Navigation System Yes AM/FM Radio Yes CD Player Yes MP3 Playback Yes DVD Playback No Bluetooth Compatibility Phone & Audio Streaming iPod Compatibility No USB Compatibility Yes Aux Compatibility Yes Speakers 4 Wheels & Tyres Alloy Wheels Yes Tubeless Tyres Yes

Advantages and disadvantages of torsion bar suspension

The main advantages of a torsion bar suspension are durability, easy adjustability of ride height, and small profile along the width of the vehicle. It takes up less of the vehicle's interior volume than coil springs. A disadvantage is that torsion bars, unlike coil springs, usually cannot provide a progressive spring rate. In most torsion bar systems, ride height (and therefore many handling features) may be changed by simply adjusting bolts that connect the torsion bars to the steering knuckles. In most cars with this type of suspension, swapping torsion bars for a different spring rate is usually an easy task.

renault

Renault made an excellent move in the Indian car market by launching the Duster compact Sports Utility Vehicle (SUV), also known as Dacia Duster in the international market, in 2012. This car made a huge impact on the position of the French auto maker in India, which was slightly shaky before the introduction of Duster. The car has done remarkably well in both, international and Indian markets. In fact, the popularity of Renault Duster paved the way for success of the compact SUV segment in India. To further capitalise on the success of the car, Renault has come up with the facelift version of the same that is set to be globally showcased at the Frankfurt Auto Show in September 2013.

Renault Duster facelift to be unveiled at Frankfurt Auto Show

Experts suggest that with the facelifted version of Duster, when launched in India, will continue to clock good sales counts. The French car maker has decided to give one of its best selling cars a new look to carve a different customer base. Apart from minor tweaks, everything else is expected to remain the same as before. However, industry experts feel that the changes made will be prominent enough to make the new facelifted version distinguished from the current one.

Sources close to the development process revealed that the French car maker will provide a more rugged look to the reworked model. The new Duster will get a redesigned grill which will now have two chrome strips. It will also feature daytime running lights along with new air intake and double-optic headlights. Also, the new air intake and larger light clusters will be hidden behind a redesigned front grille. Chrome tipped exhaust along with newly designed tail lights are the only changes to appear at the rear. Reports suggest that the yet to be launched car will also feature an Eco2 button on the 1.5-litre dCi prototypes.

Regarding the new changes, David Durand, Head of Styling for the Entry range at Dacia was quoted as saying, “We built on the appeal of the original model and its proportions. Identity components such as the grille have been modernized. We have also strengthened the 4×4 cues of the vehicle, while keeping all its useful features. New Duster gets an even stronger character while retaining its initial DNA.”

The Duster compact SUV is also expected to get a new set of roof bars with slatted supports. It will also feature a new badging and a chrome plated tail pipe along with a set of 16-inch Dark Metal alloys. Even without making any substantial changes and sticking to non-comprehensive makeover, the French auto manufacturer is quite confident of attracting new customers through the facelift. Although the changes announced are applicable for the European version of the car, it has been speculated that the new version will also debut in other markets soon after its official launch.

As of now, it can be said that the external upgrades are minor in nature. According to sources, the reason Renault would not have liked to give Duster a major changeover is that the design of the car highly contributed in its success. The car features 16-inch 'Dark Metal' alloy wheels, which will add to the sporty side profile of the upcoming car. Dacia, in its press conference, claimed that the upgrades will 'underscore the car's on-road stance and robust, "go-anywhere" character.' More news regarding the Duster facelift is expected in the near future, before the Frankfurt Auto Show in September, 2013.