Mazda engineers aimed for a quiet drive to please all on board
This series offers a behind-the-scenes look at development of the all-new Mazda CX-5 and introduces designers and engineers who played a key role in the process. In our final installment, the engineers in charge of dynamic performance explain their focus on developing a quite ride to please not just the driver but all on board.
A prototype all-new CX-5 during overseas testing
Quietness is one of the keys to a high-quality ride
Launched in 2012, the original CX-5 was the leadoff batter for the new-generation lineup, a Mazda term for models featuring the full range of SKYACTIV TECHNOLOGY and KODO—Soul of Motion design. Driving dynamics engineers had worked to provide a consistent Jinba-ittai driving feel across this lineup, and when the time came for a full redesign of the CX-5 they set their sights on enhancing this feel to the maximum extent.
Kiyoshi Hayashi, deputy program manager, drafted development targets and led development of the all-new CX-5, coordinating between the engineering, testing and research departments of the Vehicle Development Division.
Hayashi is well known within Mazda as one who has devoted himself entirely to vehicle development. Rather than schedule regular meetings, he communicated with engineers directly and made frequent visits to each department to keep the development process on track. And he placed particular importance on cabin quietness.
Kiyoshi Hayashi, Deputy program manager and (right) a scene from development
“When describing Jinba-ittai, we often use the word ‘responsive,’” said Hayashi. “But that doesn’t mean the car merely responds to the driver’s inputs. Our vision of Jinba-ittai also includes eliminating any vehicular behavior that drivers or passengers find unsettling or unpleasant and providing a quiet environment that allows them to ride in comfort. In other words, improving dynamic performance in the new CX-5 meant raising the ride quality a notch or two for all on board, and one of the keys was quietness.”
Painstaking efforts to reach the “quiet zone”
Under Hayashi’s leadership, Masahiro Awane was responsible for road noise. In developing the new-generation lineup, his team had established an index for interior noise balance. For the all-new CX-5 they set targets in the so-called “quiet zone,” where the cabin stays extremely quiet even at highways speeds or on rough roads.
Masahiro Awane, NVH performance development group and (right) the interior noise balance index
“Getting the new CX-5 into the ‘quiet zone’ was a huge challenge that required improving noise, vibration and harshness (NVH) performance in all areas, including the tires, the suspension and the body,” Awane recalled.
It involved tens of thousands of different parts from every area of the car. The project team reviewed everything they had achieved with new-generation products to date and considered whether further improvements could be made.
Testing a prototype vehicle overseas
It became an exhaustive effort to identify areas where there was still room for improvement in locations that had already been checked. Using a special tool, the team discovered that the headliner (the interior ceiling) was vibrating slightly, and driving tests revealed a resonance in a rear fender panel. The cumulative effects of such painstaking efforts enabled the team to finally reach its “quiet zone” targets for road noise in the new CX-5.
A diesel engine that is not only quite but has a pleasing sound
The development team tasked with enhancing the quality of the diesel engine also focused on sound.
Kiyoaki Iwata is a specialist in diesel engine sound and vibration characteristics. In addition to bringing greater stability and precision to Mazda’s Natural Sound Smoother and Natural Sound Frequency Control, technologies used to reduce knock noise in SKYACTIV-D engines, he thoroughly investigated the paths by which this noise enters the cabin.
Kiyoaki Iwata, Engine performance development group
By blocking and controlling noise in the body as well as engine components, he created an engine sound he describes as “not only quiet but with a pleasing, premium quality that suits the smooth acceleration feel.”
This reflects the sensibilities Iwata developed when he was dispatched overseas and dedicated himself to taking apart locally made diesel engines to research the methods used to insulate against noise and suppress vibration.
Investigating sound transmission paths in a prototype vehicle
In this way, engineers from different departments worked together to enhance the quality of the drive in the all-new CX-5. In doing so they achieved their goal of providing a more premium and comfortable ride feel not only for drivers but their passengers too. But they aren’t finished yet; a new starting line lies just ahead. The Mazda brand is evolving and its engineers face an ongoing series of challenges.