Wed 9 May 2012
Active safety: technology and more
Active safety takes many forms in the CX-5. It starts with a cockpit that enables accurate recognition and judgement by offering superior visibility. Being a Mazda, it also includes the characteristic refined driving feel and predictably responsive handling. And, as the first model of a new generation, the CX-5 is equipped with a host of cutting-edge active safety technology.
The CX-5 raises the bar for active safety in compact SUVs with a package of systems never before seen in this segment, including Smart City Brake Support and a Lane Departure Warning System (see respective boxes for more details). For those hazards lurking behind the vehicle, the CX-5 has eyes in the back of its head in the form of the upgraded Rear Vehicle Monitoring system. Like in other Mazdas, this system detects vehicles approaching from behind in adjacent lanes and in the blind spots, alerting the driver via LEDs in the appropriate side mirror. If the driver disregards an alert and switches on the turn signal lights to change lanes, the LED blinks and a buzzer sounds in the instrument panel. What’s new (besides adjustable buzzer volume) is that the CX-5’s Rear Vehicle Monitoring system – which won the Euro NCAP Advanced Award on the Mazda3 – is useful in city traffic, too, since it functions from speeds as low as 30 km/h instead of 60 km/h, as previously.
Targeting proven dangers
Improving visibility at night was another important safety topic for Mazda engineers. Traffic statistics reveal that 70 % of fatal accidents occur at night, and most of these involve vehicles using low-beam headlamps. So, as the first Mazda and one of the first in the segment, they equipped the CX-5 with a High Beam Control System (HBCS). HBCS automatically switches between low and high beams to ensure good night visibility for everyone. The system uses a camera at the top of the windscreen to detect the headlights of oncoming vehicles at a distance of 600 m (and taillights of preceding cars at a distance of 500 m), changing to low beams to avoid impairing other drivers’ vision and then putting the high beams back on again afterwards. HBCS also switches off the high beams automatically when they are not needed, for example at low speeds or in brightly lit urban areas.
Hill starts need not cause worry, either, thanks to the CX-5’s Hill Launch Assist. By controlling brake pressure to prevent the vehicle from rolling, Hill Launch Assist helps ensure smooth starts on gradients of 2 degrees or more. The acceleration sensor in the CX-5 version even has an integrated auto-learning function to better adapt to an individual’s driving habits.
And the CX-5 naturally comes with a range of additional state-of-the-art equipment, standard in all markets, including ABS with EBD (Electronic Brakeforce Distribution), brake assist, DSC (Dynamic Stability Control) and TCS (Traction Control System).
In the cockpit, Mazda optimised the position of the A-pillars as well as the door mirrors to enhance the driver’s front and side field of vision. It’s just another example of how active safety empowers the driver. Because getting from A to B safely comes down to the person behind the wheel.
Passive safety: absorbing the impact
And passive safety? Well, that’s entirely up to the car. Because this is what matters when an accident occurs. Again, Mazda engineers made no compromises, designing the CX-5 to channel impact energy away from the cabin.
As the first Mazda built with the entire range of SKYACTIV technology, the CX-5 comes with the highly rigid yet lightweight SKYACTIV-Body (see chapter 6). Utilising a straighter, more continuous frame and an extremely efficient multi-load path structure, the SKYACTIV-Body is designed to achieve top ratings in crash tests around the world.
High-tensile steel sees much greater usage than ever before in a Mazda. In fact, 61 % of the steel used in the CX-5 is of the high-tensile variety. The B-pillar and roof reinforcement cross sections, for example, have been expanded with high-tensile steel to enhance side impact protection of the cabin. The floor section, door impact beams and side sills also received high-tensile reinforcement. And the CX-5 is the first vehicle ever with extremely strong and lightweight 1,800 MPa ultra-high tensile steel, which is used in the bumpers (see previous chapter).
Such measures help channel the load outside the cabin during a collision and prevent it from deforming. The SKYACTIV-Body’s multi-load path structure, meanwhile, ensures the optimal distribution of frontal impact energy along the various load paths. And on the back of the vehicle, Mazda straightened the rear frame and optimised its shape while also joining the rear frame and B-frame sections. The upshot is that energy from a crash, whether frontal, side or rear-end impact, is simply absorbed better.
Absorbing impacts was indeed a central focus on the CX-5. It was behind the adoption of a new front suspension structure in which the engine breaks away from the suspension cross members during a crash. This maximises energy absorption by creating a larger crumple zone. The AWD model also uses the driveshaft structure to absorb the backward movement of the engine. The driveshaft detaches from the underbody during a crash and contracts, also breaking away from the rear differential. It thus absorbs energy, which is channelled underneath the cabin without obstructing the crumple zone.
Mazda even came up with an innovative system to efficiently absorb impact energy during relatively minor frontal crashes (up to around 15 km/h), making the CX-5 simple and economical to repair. In such cases, the brunt of the impact is borne in three areas – the shroud upper member, bumper and crash can, and suspension cross member crash can – with easy-to-replace bolt-fastened parts. At the same time, damage to the front frame and engine compartment is minimised.
Inside the cabin
The CX-5 interior also features all the latest in passive safety equipment. Front, side and curtain airbags are standard on all CX-5 versions. And the front seatbelts have pretensioners as well as load limiters, which mitigate the impact on the chest. The steering column, with its tilt and telescopic functionality for maximum comfort, helps prevent injury, too, shifting forward during an accident to absorb the driver’s momentum.
The front seats (described in chapter 4) were completely redesigned with a new lightweight structure. With safety in mind, the seat’s side frame was altered to eliminate contact with the occupant’s ribcage. Developers also put a strong focus on mitigating neck injuries, using an anti-whiplash design that, during a rear impact, reduces the movement and rotation of the head and torso while at the same time decreasing the load these are subject to on the headrest and seatback. They did so by raising the top of the headrest, using stiffer guide holders, making the centre section of the seatback less rigid, and improving the strength of the seat lifter to restrict backwards tilting. But in spite of all this, the seats are still 700 g lighter than the previous generation.
In the back, Mazda gave the seats an internal anti-submarine mechanism, which restrains the lower body during an accident. The seat pan on the 4:2:4 split rear seats limits the amount of forward movement of the occupant’s pelvis, while the 60:40 rear seats use a tough foam material structure for this purpose. The rear seatback frames, mounts and hinges, meanwhile, were also reinforced to better protect rear passengers from luggage and other boot cargo. And for the smallest passengers, the CX-5 has ISOFIX-compatible connections as well as top-tether anchors delivering maximum child seat safety and installation ease.
Pedestrians in focus
In yet another first, Mazda even integrated an energy absorbing design into the CX-5’s front end to minimise pedestrian injury potential. The CX-5’s bonnet, for example, has a sufficient crumple zone between it and the various engine components. The body cowl and instrument panel are also less rigid to soften the blow should a pedestrian’s head hit the windscreen. Finally, the front bumper is equipped with shock absorbing material to reduce leg injury and a rigid area at the bottom to help prevent the legs from going underneath the vehicle.
All in all, the CX-5 is remarkably safe to be in or around. In fact, it has already exhibited outstanding results during Mazda’s own rigorous crash testing under a range of real-world situations, from full and offset frontal and rear collisions to pole collisions and side impacts.
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