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SKYACTIV: Keeping the Zoom in Zoom-Zoom

Mazda takes a total approach to design.
Thursday, July 31, 2014 - 07:00
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To improve transmission oil pressure control they combined the hydraulic controls with the electronic controls into a Mechatronics module and located in the transmission. To get better shift quality, Mazda engineers came up with direct linear solenoids for quicker, more precise pressure control response giving better shifts.

SKYACTIV-MT (manual transmission)
Mazda came up with some different slants on manual transmission shifting and internal redesigns to lower weight by 16 percent and reduce friction by 1 percent. Mazda wanted to develop two levels of manual transmissions, a large and mid-size to handle different types of power plants or combinations of. Space and weight were a major concern along with that driving experience theme.

It first looked to improve shift feel and shorten the shift stroke. This required redesigning the internal stroke by adding a small module spline to move the synchronizers. It adopted lock ball type synchronizers, shift load cancellers and ball bearing on the slides to give an easier but positive feeling shift.  It rearranged the gears, moving first gear to the top shaft, using a common 2nd/3rd input gear, and doing away with the reverse idler shaft. This allowed for a more compact and lighter weight yet tough, fun shifting transmission.

Mazda wanted to keep a crisp looking, aerodynamic body that would turn heads. It was determined to lower the weight by 8 percent, improve rigidity by 30 percent and still meet worldwide safety standards. Some of the ideas it went for were “straightening” and “continuous framework.” Straightening refers to removing or decreasing underbody curves giving a straighter frame-like platform. Continuous framework means a completely bonded upper and lower structure combined into a dual brace configuration to spread any forces over the whole body. This gives the ride a tighter feel by absorbing impacts from bumps and improves crash safety. 

In this body redesign, even the door hinges were improved. The redesign also included weld-bonding of the roof as an assembly before welding it to the body structure. Body materials were also changed to a higher tensile-strength steel material.

Last but certainly not least, Mazda engineers knew the chassis needed to be revisited with all the changes made to the powertrain and body. Remember they wanted to be able to adapt to any type of power plant and lighten the overall weight. If the engineers were to control the ride and keep the fun in driving, the suspension needed to be lighter, but offer more rebound control.

Mazda improved low to mid-speed agility and high speed stability by adding electric power steering to increase yaw gain. The steering ratio was increased for better low speed response and better road feel at highway speeds. Through the use of electronic controls the turning effort is speed adaptable. It also increased both caster angle and caster trail for a better straight ahead driving feel.

The rear suspension was reworked to increase road grip and reduce rear wheel bounce. The rear suspension dampeners were moved rearward giving a straighter line for rear wheel impact control. To add to this rebound control for absorbing road bumps and keeping the wheel in contact with the road, the rear trailing arm was moved upward above the wheel centerline. This allows the wheel to swing up to roll over a bump rather than the impact pushing backward on the wheel axle causing more energy to be absorbed by the body. The engineers incorporated the old idea of “box channel frame” construction for a more rigid cross member while lowering the weight 14 percent. The front member was extended reducing the offset of the front lower control arms. The rear cross member was also given a bigger front to rear span to reduce the link offset for better wheel to body control.

Mazda engineers went back to the drawing boards to redesign their vehicles to blend with future technology while still keeping the fun in driving. They went against the normal thinking processes and made it work.  Zoom on Mazda!

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