The first car based on Mazda’s next generation of small platform Skyactiv-Vehicle Architecture, the Mazda3 takes handling, ride quality and refinement standards to a new level for a Mazda hatchback. Every element from the body, tyres and suspension has been developed to ensure that Mazda’s famous ‘Jinbai Ittai’ sense of oneness between car and driver is finely balanced.
This laser focus on delivering an engaging driving experience begins with the body and chassis of the Mazda3 and its Skyactiv-Vehicle Architecture. Featuring a body concept, which is based on a straight framework and continuous ring structures, the Mazda3 has front-to-back connections that complement the vertical and lateral connections to form multi-directional ring structures. These increase rigidity while reducing lag in the transmission of energy, which helps to maximise the function of the dampers and tyres.
The multi-directional ring structures make it possible to concentrate energy input from the road surface in specifically chosen locations, while a damping structure employed in the locations where the energy is concentrated serves as a buffer material that absorbs energy. This effectively reduces vibration that would otherwise cause noise, and it does not increase vehicle weight.
Even better, the Mazda3’s advanced and stiff chassis has allowed for a suspension system that delivers excellent communication of road inputs and enhanced ride quality. Designed with the aim of smoothing forces to the sprung mass, the suspension uses MacPherson struts in the front and a torsion beam set-up in the rear. Specific measures include bushings with a spherically shaped internal structure that makes the suspension respond to input by moving appropriately in the desired direction. In addition, the shortened distance between the lower arm front bushings and ball joints increases longitudinal rigidity in response to lateral input. One result is that it suppresses front-rear movement and supports rapid, lag-free transmission of the input.
The suspension geometry is designed to reduce the amount of steering direction change in relation to suspension stroke to realise more linear movement while cornering. The rear torsion beam structure features different diameters at its centre and outer sections. This effectively increases the rigidity of the rear tyre mounts, which enhances the vehicle’s response.
Braking performance has been developed with the aim of improved stopping performance and pedal feel. Part of the innate connection needed for ‘Jinba-Ittai’, brake pedal feedback was a key focus, with the engineering team working to ensure it’s easy for the driver to sense when the brakes start engaging. This means that they can easily adjust the rate of deceleration by backing off the pedal and it achieves a high level of rigidity that is maintained for as long as the brakes are firmly applied. Thus, the structure of the brake callipers and the movement of the piston seals that push the brake pads are optimised. The design maintains constant clearance between the brake pads and brake discs, regardless of whether the brakes are lightly or firmly applied. This reduces rolling resistance and significantly improves controllability. Mazda also paid careful attention to the muscle movement associated with operating the brake pedal. The pedal parts were redesigned to effectively leverage the movement of only those muscles best suited to pedal operation, which results in reduced fatigue and greater control.
Equal efforts were applied to other key driver engagement factors such as steering feel and weighting, plus the shift action of the gearbox. Even the Mazda M Hybrid system was engineered to adjust engine speed during upshifts to deliver a smoother shift and enhance the driver’s subconscious clutch operation.
With prolonged exposure to noise, vibration, and harshness (NVH) a cause of driver fatigue and passenger discomfort, so refinement was another key pillar of the development concept for the Mazda3. Mazda’s engineers optimised parts structures and conducted human research studies to not only reduce noise, but also control the fluctuations in and direction of sounds throughout the cabin.
The Mazda3 features a ‘two-wall’ structure, which leaves space for air between the floor carpeting and body panel beneath it and greatly improves insulation quality. The two walls are designed to match the characteristics of the fibre material attached to the carpet. This increases efficiency without adding weight. Furthermore, the amount of fibre material on the underside of the floor carpet was tuned to its specific location to achieve optimum density across the entire floor. The number of holes in the carpeting was also reduced wherever possible, while all remaining holes were virtually covered by relocating surrounding parts.
Another feature of the Mazda3 is a seal inside the parting lines between the roof panel and boot hatch. This significantly reduces noise caused by wind blowing into the gap. As a result, rear seat occupants experience a far quieter ride when travelling at motorway speeds. To further reduce road noise and vibration, the sound-absorbing headliner and floor mats in the Mazda3 quickly suppress high-frequency noise when the road surface changes from rough to smooth.
Tyres with optimised vertical spring action likewise absorb vibrations to help keep changes in the road surface from being transmitted to the ears of cabin occupants. In addition, engineers greatly increased the rigidity of the passageways through which vibration is transmitted from the tyres to the car’s suspension and body. This reduces the actual existence of vibration, which in turn minimises the amount of noise that cabin occupants perceive.
Other NVH improvement measures include optimisation of the engine control system and engine mounts to suppress unpleasant vibrations during i-stop operation. Of particular note is the belt-driven ISG used by the Mazda M Hybrid system of the e-Skyactiv G 2.0 engine. When stopping, it enables the system’s motor to move the pistons to a position where they will start again smoothly, regardless of the operating environment.