1999-2009 [Subscribe to Daily Digest] |
Members do not see ads below this line. - Help Keep This Site Online - Signup
Bi-xenon lighting provides a class-leading view
Good, strong, powerful lights have always been a Saab speciality. The performance has partly been due to the engineers' own survival instincts - you need a good spread of light when you're peering through the gloom and murk of a Swedish winter. No wonder Saabs win car-magazine lighting tests - even against xenon-equipped rivals. It's all part of Saab's in-built safety culture.
So far, though, all of this has been achieved with conventional halogen-bulb technology. But that's about to change: bi-xenon lights are now available as an option on the new Saab 9-5 range. And the results are staggering. The light spread is 60 per cent better than with Saab's already exemplary halogen bulbs. Which means there's a far greater chance of spotting an elk that's about to wander out of the Swedish mists and onto the road…
What is bi-xenon lighting?
Well, let's start with halogen bulbs first. Halogen bulbs use reflectors to direct the spread of light. But they're simply not as powerful as a xenon lamp.
Xenon lighting uses a bright, white gas-discharge lamp - unlike a halogen lamp, in which a filament glows. Xenon lights work on an AC current while halogen bulbs are powered by the battery's DC current. To provide the xenon lights with an alternating current, an electronic ballast (starter module), with a high-voltage start-up, transforms the normal voltage into AC.
Until relatively recently, only xenon light systems have been on the market. They used a combination of xenon lighting with its projector modules for dip-beam work and halogen bulbs with reflectors for high-beam situations, simply because the xenon projector modules just weren't big enough to work effectively on high beam.
However, two years ago, the first bi-xenon lights were made commercially available, the projector module featuring a shutter which rises to reveal the whole lamp on high beam. That's when Saab decided to incorporate the lighting system as an option on the new Saab 9-5 range.
Saab's goal - a world-class lighting system
"It was a very exciting time for us," explains Ingemar Knutson, manager of exterior lighting systems. "We had the opportunity to create a world-leading lighting system on the new 9-5 range, using a xenon gas-discharge lamp both on dip and on high beam, with a halogen bulb as an additional auxiliary high-beam unit. We are one of the first with such a system.
"We worked very closely with the exterior designer Ola Granlund to ensure that we had enough surface area to make the bi-xenon lights work really efficiently. It's really important to use your source in the right way - if you have very slim lights then you don't have very much surface area to make the reflectors work properly. Sure they look good, but they don't do the job well enough. I think ours is a good compromise."
World-leading safety standards are key to Saab's approach to building motor cars. Comparing the light output of a halogen lamp to a bi-xenon lamp shows the difference. The Saab halogen bulb throws out 1,500 lumens - the lumen being a measure of light. The bi-xenon simply doubles that to 3,000 lumens.
Xenon light is also a white light - unlike the yellow cast from a halogen bulb - with a terrific spread, allowing the lights to illuminate the sides where trees meet the edge of the road. The white light also benefits people suffering from deteriorating night vision, which becomes particularly prevalent in middle age, allowing them better vision in the dark.
Development of the bi-xenon lights
Saab engineers worked closely with lamp supplier Valeo to develop the necessary performance required by Saab's engineers.
Among the issues to be resolved was the necessity for a dynamic self-levelling system, so the lights wouldn't affect other road users as the car body travelled up and down over road imperfections. Sensors are connected to the front and rear axles and obtain information from the suspension system on compression rates. This information is fed to a motor which reacts in milliseconds so that the reflector 'shades' the bulb. The bulb itself remains fixed in position.
There's also a system of filters, so that the motor can correctly understand the information it receives, otherwise the shade would be constantly in motion to no benefit.
Initially, Valeo made photometric prototypes for laboratory testing. These prototypes were then tested and measured on the road, using a special bumper fitted out with the lamps, before moving to the final prototype stage and then on to series production.
However, to ensure world-leading performance, Saab has for European markets included a halogen bulb for increased high-beam illumination. This provides supplementary brightness in addition to the beam from the bi-xenon lamps. "It gives our light units the extra performance," says Ingemar. "Halogen just gives us that extra bit of spread. It makes all the difference.
"We have our own internal Saab scale for assessing lamps," continues Ingemar. "We look at all the small details - I really believe that's what makes us the best. On a scale of 0 to 10, a good lamp will register seven. When we started with bi-xenon it was only at four. By the time we finished, it was up to nine - that's how good it is."
Powerjets for new clear-lens design
Bi-xenon lamps have necessitated using clear plastic lens covers. While looking more modern and contemporary, the new clear-lens philosophy has meant dealing a blow to one of Saab's safety landmarks: the headlamp wash/wipe system. Saab was the first car manufacturer to introduce this - on a Saab 99 in 1971 - and the benefits of clean headlamps in poor driving conditions were plain to see.
The new clear plastic covers are more resistant to stone chips and breakage as well as being lighter. A head lamp with a plastic lens is also better for avoiding condensation than one with a glass lens. The plastic lens gets warmed up in a more efficient way to dry the condensation. This plastic lens would be scratched by the traditional wash/wipe system. Instead, the job is now done by high-pressure jets which rise from the bumper to spray cleaning fluid over the lens covers.
But here, too, Saab engineers have done a really thorough job on the system. "There's a legally prescribed 'dirt' you have to use to measure the washers' performance," explains Ingemar. "You then have to go through a dirt/wash cycle and measure the deterioration of the light output. Which of course we did. But we also went and found some real mud. Swedish mud. And tested the system properly. Because if we weren't going to have a wash/wipe system, then we had to have really powerful jet sprays that worked in a Swedish winter."
Needless to say, the Saab jet sprays now exceed the legal requirement. By 15 per cent...
"I think we have a lighting system that is truly world class," concludes Ingemar. "It's the result of our focus on real-life strategies. We have to make Saabs work, and work well, even in the most extreme conditions. And often that means in Sweden!"
New bi-xenon lights - key points
New bi-xenon option, with dynamic self-levelling, provides world-leading lighting system
Bi-xenon lamps 100 per cent more effective than Saab's class-leading halogen lighting system
Large surface area helps provide superior performance
Clear light lens now standard across the new 9-5 range
Powerful washer jets replace traditional headlamp wash/wipe system
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
 |
 |
 |
 |
 |
