Saab 9-3: Safety

Safety Optimized for the Real World

• Improved safety cage and deformable structures
• More “Real life” crash configurations
• Second Generation Saab Active Head Restraints (SAHR)
• Side curtain airbags for certain side and severe frontal impacts
• Sophisticated sensing for airbag/seatbelt pretensioner deployment
• Excellent driving safety with EBD, CBC and ESP

“This is a car loaded with safety. We have incorporated some of the most effective features in the marketplace today.”
– Per Lenhoff, Head of Crash Safety Development

Saab has a long tradition of successful work with car safety. But the pursuit of improved safety is a never-ending quest. The design of an all-new car, such as the new Saab 9-3, has given engineers a great opportunity to apply some of the lessons of real life, raising their safety benchmark ever higher. As a result, the new Saab 9-3 is expected to be one of the safest cars in the world.

For Saab, car safety involves two key areas: crash safety (often called passive safety) and driving (or active) safety. The new 9-3 features important advances in both.

Crash impact resistance benefits from a number of structural systems first seen on the larger 9-5 model, and the introduction of new occupant protection measures, including second generation Saab Active Head Restraints (SAHR) and Side Curtain Airbags. Front and side impact sensing is more precise, and the deployment of counter-measures, such as the dual stage front airbags and seatbelt pretensioners, is more occupant-friendly.

Greatly improved chassis dynamics, including steering, brakes and suspension, keep the driver even more in control and, therefore, better able to avoid a crash. Driving safety is advanced still further by the availability of EBD (Electronic Brake-force Distribution), CBC (Cornering Brake Control) and optional ESP (Electronic Stability Program). These systems are described in the Chassis section.

More “Real-Life” crash configurations
Saab crash tests are designed to replicate what happens in real crashes on real roads, based on the findings of Saab’s own database covering more than 6,000 real-life accidents involving Saab cars.

The structural design and counter-measure deployment of the new 9-3 is, therefore, designed for real-life safety. It has been evaluated in dozens of different crash configurations, which take occupants of all sizes into consideration and is a record number for Saab in a new model development program.

Prototype tests are carried out in the laboratory and outdoors in a wide range of speeds and configurations including, frontal car-to-car, moose impact, frontal under-ride, side swipe, truck-to-car side impacts and roll-overs.

Advanced crash simulations, using finite element methods (FEM), help find the right solutions before any prototypes are built. Support by simulation is used throughout the development process for structural design, as well as for tuning the occupant protection systems, such as seatbelts and airbags.

Safety structure
Saab’s strongest -yet steel safety cage is designed to help protect the passenger compartment. It is fabricated from high-strength steel with most sections completely closed for additional strength, and all joints are designed to help prevent tearing under severe impacts.

The front and rear crumple zones are made up of carefully shaped steel members designed to absorb, distribute and deflect as much impact energy as possible to help more effectively shield the passenger compartment.

Three distinct load paths on each side of the front structure channel impact forces through the front sub-frame, along the longitudinal members and through the upper rail. The longitudinal members have large sections that extend right through the floor of the car to the rear seat area.

The three load paths are connected transversally via cross-members, the most important of which is the bumper beam. This is made from boron alloy steel with a very high yield strength. This highly effective design is a development of the system first seen on the 9-5. The beam is designed to spread impact forces across the front structure, allowing acontrolled and predictable deformation, almost regardless of the point of impact.

For side impact protection, Saab engineers have developed the B-pillar, side sills and door beams to behave as a single, integrated structure, designed to deform in a controlled and predictable way. A key part of this strategy is the “pendulum” movement for the B-pillar, a concept also used on the 9-5.

In effect, the B-pillar is “hinged” from the roof rail of the safety cage. It has highly strengthened upper and middle sections so that, in an impact, it is designed to bend inwards at the bottom, deflecting lateral forces downwards towards the floor, away from the more sensitive occupant head and chest areas. The door beams support this structure and the bottoms of the doors also interlock with the reinforced side sills to allow the whole side structure to play a load-sharing role.

The door beams also have a major load-carrying function in side impacts with narrow objects, such as a tree, when the B-pillar is not engaged.

At the rear, two more longitudinal members are designed to buckle and deform downwards in a two-phase action. In rear-end impacts, they are designed to dissipate impact energy towards the lower C-pillar area and at the same time also force the spare wheel, mounted flat in the trunk, to rotate to a more vertical position for additional rear passenger protection.

The fuel tank is mounted low down in front of the rear axle, far away from any point of impact. Saab has long experience in working with safety regarding fuel system integrity.

Second generation Saab Active Head Restraints (SAHR)
Crash investigation findings have already demonstrated the effectiveness of the innovative Saab Active Head Restraints (SAHR) in helping to protect front-seat occupants against neck injury, one of the most common forms of injury.

Now Saab has developed a “second generation” version for even faster activation in rear impacts at lower speeds. The head restraint is activated as soon as the lower back is pressed into the seatback by the occupant’s inertia during a rear impact.

The restraint is fixed to the top of a frame inside the seatback, which pivots at its mid point. As the occupant’s lower back comes into contact with the bottom of the seatback, the upper half of the frame carrying the head restraint moves forward in the opposite direction. In this way, the occupant’s head movement during a rear-end impact is minimized, helping to prevent neck injury.

The SAHR system is entirely mechanical and, after activation, the restraint automatically springs back to its passive position ready for further use. It is designed to give adequate protection, even if the adjustable restraint is set at an incorrect height. Although for best protection, it should always be adjusted to the prescribed height directly behind the occupant’s head.

Side Curtain Airbags
The new 9-3 becomes the first Saab to include a roof-mounted airbag. It can play an important function throughout an entire crash sequence and is programmed to deploy in severe frontal, as well as side, impacts.

The Side Curtain is installed from the A to the C-pillar, up in the interior headlining above the side windows, and offers head protection to both front- and rear-seat occupants. To improve cushion kinematics during inflation, it is activated from the B-pillar area. The airbag remains inflated for up to 3 seconds in order to help prevent a passenger’s head from striking the A-, B-, or C-pillar, or exterior objects, during the course of an impact sequence. In side impacts, it is activated together with seat-belt pretensioning and the seat-mounted thorax side airbag. It is also deployed in severe frontal impacts, where stage 2 activation of the front airbags is used.

For improved impact sensing, there are now two side-impact sensors in each side of the new 9-3, one in the sill near the B-pillar and the other in the lower part of the C-pillar. These sensors measure acceleration rates and a decision on airbag deployment is taken by the central sensing and diagnostic module (SDM) in a few milliseconds.

Adaptive front airbags
Dual stage, front airbags are revised for a more occupant-friendly deployment in frontal impacts. Two sensors in the front bumper beam detect impact severity, a sensor in the seat track communicates seating positions and a switch in each front seatbelt buckle indicates whether or not the belt is being worn. All this data is sent to the centrally located SDM, which within milliseconds, chooses between activation of the seatbelt pretensioners alone, or in combination with a single or two-stage inflation of the airbags. In a severe impact, where stage 2 of the front airbag is used, the Side Curtain Airbag will also deploy for additional head protection.

A crash with a relatively low level of impact energy would, for example, require less airbag pressure and, therefore, a slower rate of inflation than a more severe, high-energy impact. Likewise, a short driver sitting close to the steering wheel or a front passenger sitting close to the dash fascia would also benefit from a softer, lower pressure inflation.

Conversely, if the occupant is not wearing a seatbelt, the system also takes this into consideration. In this way, the airbags can be deployed differently for the driver and passenger, depending on their requirements.

Seatbelt load limiter and reminder system
Despite the use of airbags, seatbelts are still the single most important occupant restraint system. Three-point belts are used on all five seating positions.

For all outboard occupants there are belt pretensioners and load-limiting functions to remove belt slack and to help reduce belt loads in severe crashes. The pretensioner is mounted on the belt retractor and is activated by a signal from the airbag sensing system, igniting a small pyrotechnic charge that retracts the belt.

The load-limiting function consists of a torsion bar inside the retractor that, at a pre¬determined load level, will start to deform and thus reduce the belt load.

Saab has used a seatbelt reminder function since 1974, and to further inform customers of the importance of belt usage, a more advanced system is now introduced. This system uses tell¬tales and warning sounds, based on speed and time to independently remind the driver and the front passenger when they are not wearing their seatbelts.

“Occupant-friendly” interior
A great deal of expertise has gone into designing the interior surfaces and materials to be “occupant-friendly” in a collision or rollover. In particular, the front areas of the cabin near the knee and lower leg, the headlining and all pillar linings are well bolstered to help prevent occupant injury.

In the foot area, protective padding reduces the risk of foot injuries and the driver’s pedals are designed to break away in a severe impact. The steering column and steering wheel are energy absorbing also.

Passenger safety is the main reason why door armrests and inner door handles are always recessed inside a Saab. It is also one of the reasons why the new 9-3 retains Saab’s traditional floor-mounted ignition switch, well away from sensitive knee and leg areas.

Another Saab tradition in passenger safety is the importance of ensuring good protection against the hazard of shifting loads. The split-fold rear seatback has been carefully engineered for strength in this area, and robust tie-down loops are also installed on the floor of the trunk to help secure cargo.

New Saab 9-3 In Focus: Non-stop, stop lights!
If one of the rear stop lights fails, driving safety will be not be compromised, thanks to a dual function built into the rear lights.

The stop light function – extra light intensity whenever the brake pedal is pushed – is programmed into the outer of the two light bulbs in each rear light cluster. If this bulb fails, the brake light function is not lost because it is automatically switched to the other bulb. This is possible because the usual voltage restriction (13.3 > 6.3v), which is lifted whenever the brake pedal is pushed, is applied to both bulbs. Normal service is automatically resumed when the broken bulb is replaced.