The all-new CX-5: engineers’ quest for a quieter ride
‘Every passenger should experience the joy of being in the car, not just the driver.’
In building the second-generation CX-5, Mazda engineers tasked with improving its driving performance were united in this vision – and agreed that the focus of their makeover should be on ‘quietness’.
Kiyoshi Hayashi, deputy program manager in charge of coordinating the design, testing and research departments within the Vehicle Development Division, explains their strategy. ‘In order to enhance the CX-5’s dynamic performance, we needed to improve the experience for all passengers several times over, and the key to achieving that was quietness.’
Having spent his whole career in vehicle development, Hayashi avoids calling regular meetings, preferring instead to communicate one-on-one with each engineer, flitting from department to department to rally their efforts. This time, he wanted to impress on his team that quietness inside the cabin was critically important.
‘We often use the word ‘responsive’ to describe the Mazda driving experience, but we don’t just mean that the car reacts as the driver wants it to. We also mean that the car moves in a way that doesn’t make the other passengers feel unsettled or uncomfortable. All passengers should be able to enjoy a smooth ride inside a quiet cabin.’
Exhaustive efforts to conquer the ‘quiet zone’
Masahiro Awane, the engineer in charge of reducing road noise, reflects on the difficult task he faced.
‘It was a huge challenge; we needed to improve the NVH (noise, vibration and harshness) performance in all areas including the tyres, suspension and body.’
Awane’s team christened their target the ‘quiet zone’, in which the cabin stays extremely quiet even as the car drives on motorways or rough terrain. To achieve this ‘quiet zone’, they had to reexamine almost every aspect of the CX-5, amounting to tens of thousands of small parts. They took apart entire sections that they’d previously thought were in the best possible condition, and reassessed them to see if they could be improved even further. It was thorough, painstaking work.
The team’s efforts were duly rewarded with fruitful results: for example, they discovered that the headliner (interior ceiling) was vibrating ever so slightly, while driving tests revealed a resonance in a rear fender panel. Thanks to inspection upon inspection of each tiny part, the road noise of the CX-5 was successfully reduced and brought into the ‘quiet zone’.
Uncompromising quality of the diesel engine sound
While the rest of the team was obsessed with reducing noise, there was one man who was preoccupied with the quality of sound: Kiyoaki Iwata, a specialist in diesel engine sound and vibration.
‘I wanted to improve the texture of the diesel engine sound. It’s not enough that it’s quiet – it also needs to be a pleasing, premium sound that compliments the feel of smooth acceleration,’ Iwata recalls.
To achieve this, Iwata improved the existing technologies that reduce knocking noise (caused by engine problems) to make them even more precise and stable, and made a thorough investigation into how knocking noise makes its way into the cabin. Finally, he worked on the body as well as the engine components to block and control noise.
Iwata had previously spent time overseas, pulling apart locally made diesel engines to see how noise and vibration could be suppressed – this experience proved key to his overhaul of the all-new CX-5.
In these ways, Mazda engineers across departments came together in their quest to deliver a comfortable, quality ride for both the driver and the passengers.
With the all-new CX-5 successfully delivered into customers’ hands, the engineers are already rolling up their sleeves for the next challenge.
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