POWERTRAIN
Zoom-Zoom Powertrain Lineup
A new family of four-cylinder gasoline engines, next-generation common-rail diesel engines with breakthrough environmental capabilities and a new 3.0-liter, low-friction aluminum V-6 engine make the launch of the new Mazda 6 much more than a new midsize car platform.
It is the essence of Mazda 6's Zoom-Zoom - a new range of modern powertrains that exemplify Mazda's new spirit of leadership and innovation.
Mazda Motor Corporation's new family of 4-cylinder engines is the latest in a new range of powertrains that will establish Mazda as Ford Motor Company's center of excellence for all large I-4 gasoline engine development. The new engine will be used in a broad range of vehicles, beginning with the Mazda 6. It will be offered in three displacements: a 1.8-liter, 2.0-liter and an advanced 2.3-liter with Mazda's Sequential Valve Timing (S-VT), which improves performance efficiency, and balance shaft to eliminate vibrations resulting from free mass and momentum forces.
The new family of 4-cylinders provides Mazda with a common architecture the company can use for at least 200 future applications in the Ford Motor Company, including direct injection (DI) gasoline and the more extensive use of sequential valve timing.
But, this new gasoline engine technology is not the whole Mazda 6 powertrain story.
In select markets, Mazda 6 will introduce new Mazda-developed diesel engines with next-generation common-rail injection technology designed for environmental compatibility and outstanding torque responsiveness.
The Mazda 6 powertrain family will be available in some markets with a unique 3.0-liter V-6, also with S-VT and a new intake manifold.
"We've developed the Mazda 6 as a new, global, midsize car platform for the future," said Phil Martens, managing director product strategy, Design and Product Development. "And we've worked hard to give this platform the kind of modern powertrain technology that will do more than just compete in its segment - it will lead it."
The new powertrains offered in the Mazda 6 will be available with new computerized five-speed automatic transmissions or 5-speed manuals with gear ratios matched to the torque curves of each engine, delivering quick acceleration and quiet cruising.
High Technology 2.3-liter Engine
Among the key objectives for the new 2.3-liter engine was achieving more torque, horsepower and smoothness, while delivering improved fuel economy, lower emissions and minimal maintenance requirements. The new engine hits all of these marks, thanks to the use of lightweight aluminum, innovative engineering, such as the use of S-VT, balance shaft and a keen attention to detail.
Mazda's S-VT allows the point at which the engine's valves open and close and the duration they stay open to change with operating conditions, such as engine speed and air volume. Varying these parameters allows the engine to operate more efficiently at all engine speeds while maintaining drivability, improving power, fuel economy and emissions. Traditionally, camshafts open and close intake and exhaust valves at fixed points in the engine cycle, regardless of engine speed or air volume.
Located under the crankshaft, the balance shaft minimizes vibration by rotating at twice the speed of the crankshaft and offsetting the secondary inertia force of the rotating system. The balance shaft is fitted in its own housing and attached to the cylinder block for optimum positioning. It is driven by a gear to reduce drive losses.
Meanwhile, variable valve timing delivers more torque and more power than a conventional engine.
To achieve the aggressive targets on improving torque, horsepower and smoothness, Mazda engineers focused on several other areas, as well. First was developing a new intake manifold. Using an array of powerful computer aided engineering (CAE) tools to compare various designs and options, engineers developed a sophisticated new friction-welded nylon intake manifold with equal length runners that incorporate new devices called swirl control valves. Mazda engineers fitted these specially designed control valves into each of the intake runners, close to the cylinder head flange.
These valves or "tumble flaps" in the variable induction system are controlled by a solenoid actuator and are closed during light-load operations, such as idling at traffic lights, shifting actions and deceleration, to maximize combustion efficiency, fuel economy and emissions performance.
The valves are fully open during higher load conditions, roughly 5,000 rpm, to maximize volumetric efficiency and power output.
The intake manifold is constructed of part-recycled material. Its design improved engine sound quality by emphasizing the even-order engine harmonics - a key to the equal length design.
This innovative intake manifold design is further enhanced by the careful design of the air cleaner system. Mazda's air cleaner does more than simply clean the air. The system features a performance-tuned, bell-mounted, cold-air pickup duct at the very front of the vehicle, a large noise, vibration and harshness-tuned resonator in the wheel-arch and "organ pipes" designed to selectively feed back sporty sound to the driver under high throttle conditions.
To enhance fuel economy and reduce NOx emissions even further, Mazda engineers developed a water-cooled, electronically operated exhaust-gas recirculation (EGR) system. The EGR valve, actuated by a stepping motor, precisely redirects exhaust gas to the intake side of the engine, where it is inducted into the intake manifold through a short duct. The EGR passage is cast into the cylinder head.
To reduce engine back-pressure and to ensure quick catalyst warm-up efficiency with the 2.3-liter, Mazda uses a fabricated stainless steel exhaust manifold design of welded tubes. Unlike a conventional cast iron constructed exhaust manifold, the stainless steel exhaust manifold delivers low-heat retention in normal operation. A typical 4-cylinder exhaust manifold funnels into a single pipe and then into the catalyst.
In the Mazda design, a heat-insulating layer surrounds the portion where the four runners meet and a divider plate is located longitudinally in the exhaust pipe. This arrangement combines the heat retention benefits of a single pipe structure with the engine performance benefits of a dual-pipe structure. This concept of heat management allowed Mazda to simplify the rest of the exhaust system and eliminate the need for a close-coupled catalyst.
Eliminating the close-coupled catalyst and locating it under the floor, reduces engine back pressure, helping improve real-world performance and high speed fuel economy.
High quality stainless steel materials also were used for the extended service life of the muffler system, which has been tuned for a sporty sound quality under high-load driving conditions.
The engine and exhaust systems of all Mazda 6 variants - critical for keeping emissions low - are continuously monitored by a so-called onboard diagnostic system. The system uses a control lamp in the instrument cluster to warn the driver ("Check Engine") of a fault affecting a component relevant to pollutant emissions.
The 2.3-liter in the Mazda 6 also marks the appearance of a new engine management computer module. At its heart is a microprocessor, incorporating logic by Mazda. The system works through a CAN-bus to the chassis controls for intelligent vehicle dynamics features such as anti-lock braking and traction control. With the speed and capacity of this advanced computer chip, Mazda engineers were given the ability to fine tune the engine's performance with more extensive and sophisticated algorithms developed with the use of state-of-the-art, real-time simulation tools.
One of the side benefits of this new system is that some of the complexity of the control system required for optimal fuel economy and emissions could be simplified.
To simulate real world environments, Mazda engineers made extensive use of transient powertrain dynamometers that could be operated under extreme hot and cold conditions. These engine test facilities helped engineers simulate real world environments ranging from Artic cold to Saharan heat.
Mazda's engine development center in Hiroshima, played a leading role in this climate-controlled testing.
Lightweight Aluminum Construction
Mazda's 1.8-liter, 2.0-liter and 2.3-liter engines are made of a lightweight all-aluminum alloy construction that helps deliver superior performance and fuel economy.
Each 4-cylinder begins life as a precision gravity sand-cast cylinder block of high-grade aluminum alloy with cast-iron cylinder sleeves cast directly into the block. This closed-deck, deep-skirt cylinder block ensures a tight seal between the cylinder block and cylinder head. An aluminum alloy, ribbed ladder-frame structure, which carries the bottom bearing braces, mates to the cylinder block for optimized stiffness. But engineers didn't stop there. As the oil pan has a significant influence on joint rigidity between the cylinder block and transmission and can minimize vibration from the engine and transmission to the body, a ribbed aluminum oil pan was developed to complement stiffness properties and contribute to quiet operation.
Weight savings were obtained using a nodular cast iron crankshaft that requires only four counterweights for the 1.8-liter and 2.0-liter. The 2.3-liter engine has eight counterweights because of its larger displacement. Low friction-coated, lightweight alloy pistons with sinter-forged connecting rods for dimensional accuracy and fraction-split ends are used for a precision fit that enhances reliability and reduces noise and vibration.
Cylinder head construction is of aluminum-silicon alloy - thermally treated for strength and durability after the casting process - with an asymmetrical, four-valves-per-cylinder design. Two inlet valves (32.5-mm for the 1.8-liter; 35 mm for the 2.0-liter and 2.3-liter) are positioned at 19 degrees, and the two exhaust valves (28 mm and 30 mm, respectively) are positioned at 20 degrees. The compression ratio for the family of 4-cylinder engines varies from 9.7 to 10.8 depending on displacement and market.
The double overhead cams are driven by a hydraulically-tensioned silent chain drive, actuating the valves via mechanical tappets. Unlike previous-generation Mazda engines, the tappets are precision-fit during assembly and require no shimming. The intake and exhaust valves are nitrogen treated for durability.
Displacement variations for Mazda's new family of engines are achieved by increasing bore size (87.5 mm for the 2.0-liter versus 83.0 mm for the 1.8-liter) while keeping the common stroke length of 83.1 mm for the 2.0-liter and 1.8-liter. The stroke for the 2.3-liter with S-VT is 94 mm.
Smooth, Refined Operation
Mazda's use of S-VT and balance shaft in the 2.3-liter version of the company's new family of 4-cylinder engines provides the Mazda 6 an extra level of refinement and another level of NVH reduction.
The result is smooth, quiet operation even during spirited driving.
All 4-cylinder offerings in the Mazda 6 are mounted via a three-point torque-roll access management engine mount system. This Mazda mounting system supports the engine with two load-bearing mounts along its roll axis, one of which incorporates a hydraulic damping element to reduce powertrain shake on rough roads and reduce transmitted vibrations. A third bushed link - mounted from the transmission case to the subframe - provides rigid resistance to torque. Mazda's philosophy of separating the two primary forces on the engine mounting system leads to a reduction in powertrain vibration and harshness.
when other six-year-olds were playing with their tricycles, young Tadanobu Yamamoto was taking his first step toward becoming the lead chassis engineer who would create the driving dynamics of an all-new family of cars called the Mazda 6.
Yamamoto drove a car for the first time when he was six years old. Sitting next to his uncle on the front seat of a Mazda Karo, he was bitten early by the car bug on a quiet, rural lane in the Yokohama Prefecture of Japan where he grew up.
"I've always loved cars," said Yamamoto. "Maybe it was because the first car I drove was a Mazda."
When he grew up and became a professional engineer, Yamamoto was drawn to Mazda and its reputation for creating drivers' cars. Little did he know that he would someday create a car that would help to transform Mazda Motor Corporation in a new millennium.
Mazda 6's all-new platform was designed to compete with some of the best brands from Germany. It features a newly designed front and rear suspension that rewards the driver who wants dynamic performance, while at the same time delivering, comfortable, long-distance ride comfort.
Deep in its insightfully engineered core, the new Mazda 6 owes a small
debt to the Zoom-Zoom of the Mazda Karo that was Yamamoto's first drive all
those years ago.
Tadanobu Yamamoto
Chassis development staff manager
Whether it is lifting weights, collecting Gundam models or developing a new range of powertrains for the Mazda 6, Kenichiro Saruwatari gives it his all.
Saruwatari loves his job as much as his hobbies.
Today, as assistant manager of powertrain development, Saruwatari points with pride to the Mazda 6's new range of powertrains.
"The new four-cylinder gasoline engine produces a pleasant sound by improving the resonance sound," Saruwatari said. "The new common-rail engine diesel engine is a highly efficient engine that minimizes emissions. And the sequential valve timing on our new 2.3-liter four-cylinder and 3-liter V-6 deliver fun-to-drive power."
Saruwatari takes a hands-on approach to his work.
"We conducted extensive drive tests to develop Mazda 6's performance and dynamic capabilities," Saruwatari said. "We worked to optimize the gear ratios to improve driving quality. We also worked on little things, like improving the movements of the pointers for the speedometer and tachometer to reflect this vehicle's upscale image."
In his spare time, Saruwatari enjoys skiing and collecting Gundam models, detailed, robotic action figures that are popular in Japan.
"I like Gundam models and I have an extensive collection of them."
Kenichiro Saruwatari
Powertrain assistant manager
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