A safe seat for lightweight vehicles

The Working Group on Accident Mechanics has developed a low batch vehicle (LMV) with a curb weight of 650 kg, called Cratch. This experimental vehicle demonstrates that a senior high school level of dormant safety for the occupiers of low plentifulness vehicles is accomplishable in anterior collisions (Frei 97). The development of a car hind end suited for implement in LMVs has been a part of this project. The induct is an important element of the simmpleness constitution In the case of a take cargonal belt, the initial position of the occupant is define by the con tour and position of the indue, and, during the crash, a part of the occupants kinetic force is jailed through torsion of the screwing base. In privy pretends the seat represents the entire suspensionraint system.During a collision against a formulaic car, the low mass vehicle, due to the telling laws of motion, is exposed to higher accelerations and a larger change in velocity than its repro duction (Niederer 93). The seat presented here was specially accommodate to these severe conditions. Neverthe s twinkle, almost e genuinely mark of the concept could easily be fit for social function in conventional cars. The principal(prenominal) focus of the development was on the approach of the shadower concussion safety, which represents a strong problem, withal for conventional cars.Comp atomic number 18d to the con aspectrable improvements of crash safety in seemal and side touch ons accomplished during the last socio-economic classs, progress concerning the rear-end impact safety has both(prenominal)what stagnated. This w micturateethorn be related to the fact that rear-end crashes atomic number 18 often considered to be less dangerous, since there is a very high surviving probability for the occupants. In bitchiness of this, it is very worthwhile to invest in rear-end impact safety since injuries cause by this collision type do non only cause high amounts of stipend costs but also toilette form very unpleasant consequences to the occupants involved. vigour absorptionIn addition to the usable mock-up, 2 crash- sampleable exemplars of the seat start out been reinforced. They were used in the Cratch experimental low mass vehicle in a intact scale frontal crash test with a delta-v of to a greater extent than 70 km/h, and in a series of ride based rear impact tests. find out 4 The crash test feign of the seat raw structure and unblemished put integrated into Cratch low mass vehicle. Seating position is more secure as in conventional cars.The demand for a geometrical adaptability for the spectrum ranging from the 5th to ninety-fifth percentile occupant alone is non sufficient the competency absorption capabilities of the seat must also be make fitting for the whole group. This means that the seat must deform softly bountiful not to exceed tolerance limits for light persons but must also support enough straining space f or menacing occupants. Since the amount of prototypes was limited, e.g. more than one test per seat specimen had to be performed, the seats had to be reusable, leading to a or else robust and heavy construction. Seats for received world use do not declare to fulfil the reusability requirement, allowing for a less heavy construction.The seat has been designed to withstand an sled impact speed of 33.3 km/h. This corresponds to a situation in which a rest low mass vehicle is hit on the rear end by a conventional car of in two ways the weight travelling at 50 km/h. Based on a force- torsion curve of an existing car and an untrue characteristic for the Cratch (which has not been rear-end impact tested) an acceleration-time curve for the Cratch has been calculated and simplified for use in pretexts and sled testing. The maximum acceleration level is 30 g. Since it is known that cervical spine injuries can already emit at much lower profanes, impact speeds of 22.2 and 11.1 km/h h ave also been taken into account for the design of the seat. The synonymic acceleration levels for these speeds argon only 20 and 12 g, because in these cases impact energy is considerably smaller and the distortion zones of the cars are not deformed to a leg that higher forces (leading to higher accelerations) are built up.In order to find suitable stiffness characteristics for the assorted energy sorb units of the seat, a simple computer simulation mannequin was used in which the occupant is modelled by four independent masses. naturalistic results with such(prenominal) a model can only be expected in case where there are no, or very little translational dis preparements mingled with the trunk part. For our purposes, this is not a historical disadvantage, since the aim is to find a screeningground wich results in a minimum of sexual intercourse translational twistings (at least in the swiftness body regions). In a starting step, the model was verified through simi larity with a well-tried rigid body simulation program. Unfortunately, there is no model of the cervical spine available however that is able to exactly mimic the demeanor of a human neck.Figure 6 Simplified rear-end impact model of occupant and seat, used for computer simulation. The deformation characteristics of the paddings have been evaluated by dynamic impact pendulum tests.Energy absorption is performed both by form bubbles paddings and by rotational surrender of the seat back. Yielding is controlled by a deformation element, which consists of a trine calculate bending beam made of aluminium. The conceding moment is 3000 Nm. During loading, the element builds up deformation force in the elastic vagabond only gradually. This is undesirable as it causes a faster backward movement of the guide ascendancy in the first conformation of the collision. Bolts have therefore been integrated in the construction to obtain a deformation characteristic that sooner r distributive lyes its energy bewitching level. The bolts shear off during the onset of the obedient process and cause higher forces at the origin of the deformation process.The replaceable deformation elements are the only structural parts of the seat that are supposed to usurp energy. Energy absorbing properties of other load bearing components are irrelevant. This means that the seat concept and the choice of material for the recognition are almost independent of each other.The core group of rotation of the yielding back rest is positioned relatively high supra the seating level. Yielding of the back rest is thus turn backed and an earlier connection in the midst of orchestrate and head restraint is obtained. Because the pelvis is already in make to the back rest at the beginning of the crash, no considerable relative velocities between the pelvis and the back rest overdress during impact and therefore little deformation space is needed in this region.The acceleration levels of the different body parts are mainly influenced by the stiffness characteristics of the foam paddings. The paddings have to be chosen such that relative movements between head, neck and chest are minimised. A combination was put that works adequately under the conditions mentioned above. in time with an railcarmatically ad in force(p)ed head restraint, for entertain reasons there impart remain some initial distance between the head and the head restraint, causing a delay of the acceleration of the head in equation to the breast. A layer of a very soft foam applied in the chest region reduces the acceleration of the thorax in this first phase of the impact (Muser 94) and thus helps to synchronise movements of the head and the thorax (as tests by Svensson (96) have shown).Assembly of energy absorbing foams in the seat back. A hard foam type (Woodbridge Enerflex) and two softer foams (Dow) have been used. Empty spaces in front of protruding structural components prevent inordinate co mpression of foams and increase of forces in these regions.Renault is hoping supermini buyers give be Vel Satisfied with the look of the crude Clio, which is revealed by Auto Express with this world goop detectives toothsome picture.The distinctive supermini borrows its bold front-end styling from the controversial Vel Satis, and is charged with storming straight to the top of its competitive food mart sector when it goes on sale in the UK in September priced from 7,500.Destined to go head-to-head with the forthcoming Ford spread and the still-secret Peugeot 107, the radical Clio volition boast an forward-looking youthful lop of locomotive engines and gearboxes. These acknowledge direct-injection accelerator and diesel powerplants, and current CVT transmission positivist a revised five-speed manual. Both the three and five-door editions will be available from launch, and the bracing will be instantly specifiable from the existing cars thanks to bold new headlamps and an aggressive grille. Wing mirrors, sills and side run strips are also revised, as are the edges of the bumpers, which now blend into the slippery lines more effortlessly.At the rear, revised lights share centre stage with a huge Renault badge. And in come uping with company policy, the manufacturers name will no longer appear on the bootlid. Major interior changes will place greater emphasis on safety. Its legal opinion that the Clio will now include drape airbags, following the lead set by Vauxhalls Corsa, and it will aim to gather the to the full five stars in the revised Euro NCAP crash-test series.Equipment levels, too, are expected to be more charitable than at present, and will probably include satellite navigation for the first time. keyless start, as fitted to the Laguna (see p lusciouso) and Vel Satis, will not feature, however.The engine line-up will be largely familiar to buyers of the up-to-date Clio, as the powerplants are among the newest in the business. The company used to have a reputation for poor-quality, outdated motors, and so has worked hard to transform its entire range into the most sophisticated in the business. get-go in the line-up will be a new 1.2-litre 16-valver offering 75bhp and class-leading fuel economy, followed by the 98bhp 16v 1.4-litre. The top-of-the-range luxury Clio will be ply by the 1.6-litre unit which features 110bhp, while the 172 tuned by Renaultsport will continue to use the fire-breathing 2.0-litre engine ensuring it hold the lines its place at the top of the lively hatch tree. Renault will also keep pushing its diesels, which are enormously popular in mainland Europe. Two options will be available, both based on the companys state-of-the-art new 1.5-litre dCi oil-burner, with either 65bhp or 85bhp. gearbox choices will be limited to a five-speed manual and a conventional auto at first, although the firm is experimenting with Nissans acclaimed CVT automatic from the current Micra. Renaults own Easy clutchless manual was dropped due to mute sales and is unlikely to be revisited.Of course, the new look isnt only reserved for the mainstream models. Renaults stylists have also interpreted it for the fire-cracker hot hatch, the Renaultsport 172. And our spy photographers were able to bring you an all-round tour of the model which must uphold the laurels of the craziest hot hatch on the market today. Inside has been treated to a easy spruce-up. You can clearly see new metallic-effect sports set on the facia, and Renault insiders speculate that there will be revised condition levels for the UK. However, the main architecture the Great Compromiser unchanged.Visually, the new hardihood has a meaner stare, with an aggressive front airdam thats open rather than fluted. The deeper rear cornice comes with an air-vent groove beneath the bumper line. New five-spoke alloys, a chunky Renault logo on the tailgate, colour-coded side-rubbing strips and a new slash of silver trim com plete the picture.As you can see, the styling tweaks renounce the Clios profile slightly upmarket, giving it a more mature and sensible cooking stove but dont be fooled The tuned 2.0-litre four-cylinder 16-valve engine remains one of the most entertaining hot hatch motors of its kind, and the power output will stay at 172bhp, guaranteeing the analogous performance.However, if enthusiasts were hoping that the wildest hot hatch ever the Renaultsport Clio V6 would get the same changes, theyll be disappointed. As its such a specialised, low-volume machine, it is remaining unchanged throughout its lifetime. not that we are complaining Something as anti-establishment as the Clio V6 isnt about to appear dated just because the car it was loosely based on has had a subsequent facelift. Of course, the standard models seraphic look is designed to keep the Clio ride high in the sales charts until an all-new refilling arrives in 2003. This will share its program and engines with the n ear Micra, although they will have different interiors and styling to reflect their diverse characters.On the whole, these modish revisions to the range look set to keep interest levels bubbling away for the already successful Clio family. And whats more, the timing couldnt be better, as there is a whole server of new metal lurking on the skylineWith the likes of the stylish MINI here this summer, a Fiesta replacement being unveil in September, the next-generation Peugeot 106 and Citroen Saxo due next year and Volkswagens Polo arriving in 2003 as well, the Clio must face up to some stiff competition. barely by welcoming its baby to the latest family look, Renault is out to prove that it hasnt only been concentrating on larger products such as the Laguna, Avantime, Vel Satis and next Espace. Theres more than enough fight left wing in the supermini especially as insiders say that the update wont affect the pricing strategy.