Mazda Teams with Toyota For Hybrid Powertrain

Mazda_SKY-G_EngineMazda Motor Corp. has agreed to lease a hybrid drivetrain technology from Toyota Motor Corp. The deal gives Mazda access to the electric powertrain system used in the third-generation Toyota Prius. Mazda Executive Vice President Masaharu Yamaki said the electric-gasoline powertrain will debut in 2013 in a Mazda-brand hybrid for the Japanese market. Mazda didn’t announce plans for overseas versions, but a spokesman said selling the car in North America is a possibility.

The agreement helps Mazda meet its goal of improving fleet fuel economy 30 percent by 2015 compared with 2008 levels. Mazda already has rolled out plans for a more efficient gasoline engine, called the Sky-G, and measures such as weight reduction and idle stop technology. For Toyota, the deal also pushes its hybrid technology closer to becoming a global standard. Leasing it to other companies is not only a cash stream for the world’s biggest auto company, it’s also a potent way to guarantee volume for its suppliers, which drives down cost.

Teaming with Toyota signals another Mazda break from Ford, which reduced its stake in the Japanese automaker to 13 percent, from 33 percent in 2008. Since then, Ford and Mazda have embarked on largely separate powertrain strategies. While Ford is chasing greater fuel economy with its turbocharged EcoBoost engines, Mazda is developing its own line of Sky engines, which rely mostly on direct fuel injection.

The four-cylinder, direct-injection Sky-G gasoline engine will range between 1.3 and 2.0 liters and deliver 15 percent better fuel economy than current engines in the same class. Its diesel partner, the Sky-D, will get a 20 percent increase over today’s offerings.

Posted by reedman on Apr 23 2010 in Mazda Technology

The Great Rotary Engine

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Throughout the automakers history, Mazda has used the rotary engine in various models. Today, Mazda is the only automaker to use this type of engine in a production vehicle.  The Wankel (or rotary) engine currently resides in the Mazda RX-8 sports coupe, and previously was found powering the Mazda RX-7. The Wankel engine is a type of internal combustion engine which uses a rotary design to convert pressure into a rotating motion instead of using reciprocating pistons. Its four-stroke cycle takes place in a space between the inside of an oval-like epitrochoid-shaped housing and a rotor that is similar in shape to a Reuleaux triangle. This design delivers smooth high-rpm power, from a compact size. Since its introduction the engine has been commonly referred to as the rotary engine, though this name is also applied to several completely different designs. The engine was invented by German engineer Felix Wankel. He began its development in the early 1950s at NSU Motorenwerke AG (NSU) before completing a working, running prototype in 1957. NSU then licensed the concept to companies around the world, who have continued to improve the design.

Because of their compact design, Wankel rotary engines have been installed in a variety of vehicles and devices such as automobiles including racing cars, along with aircraft, go-karts, personal water craft, chain saws, and auxiliary power units. The most extensive automotive use of the Wankel engine has been by Mazda. In the Wankel engine, the four strokes of a typical Otto cycle occur in the space between a three-sided symmetric rotor and the inside of a housing. In the basic single-rotor Wankel engine, the oval-like epitrochoid-shaped housing surrounds a rotor which is triangular with bow-shaped flanks, a three-pointed curve of constant width, but with the bulge in the middle of each side a bit more flattened. From a theoretical perspective, the chosen shape of the rotor between the fixed apexes is basically the result of a minimization of the volume of the geometric combustion chamber and a maximization of the compression ratio, respectively. Thus, the symmetric curve connecting two arbitrary apexes of the rotor is maximized in the direction of the inner housing shape with the constraint not to touch the housing at any angle of rotation.

Mazda RX8Despite poorer fuel economy there are some advantages of rotary engines. They are considerably simpler, lighter, and contain far fewer moving parts than piston engines of equivalent power output. For instance, because valving is accomplished by simple ports cut into the walls of the rotor housing, they have no valves or complex valve trains; in addition, since the rotor rides directly on a large bearing on the output shaft, there are no connecting rods and no crankshaft. The elimination of reciprocating mass and the elimination of the most highly stressed and failure prone parts of piston engines gives the Wankel engine high reliability, a smoother flow of power, and a high power to weight ratio. Because of the quasi-overlap of the power strokes that cause the smoothness of the engine, and the avoidance of the 4-stroke cycle in a reciprocating engine, the Wankel engine is very quick to react to throttle changes and is able to quickly deliver a surge of power when the demand arises, especially at higher rpms. This difference is more pronounced when compared to 4 cylinder reciprocating engines and less pronounced when compared to higher cylinder counts. In addition to the removal of internal reciprocating stresses by virtue of the complete removal of its reciprocating internal parts typically found in a piston engine, the engine is constructed with an iron rotor within a housing made of aluminium, which has a greater coefficient of thermal expansion. This ensures that even a severely overheated Wankel engine cannot seize, as would likely occur in an overheated piston engine.

Posted by reedman on Oct 31 2009 in Mazda Technology, Uncategorized