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116-772: The Mazda Savanna is a rotary-powered automobile sold by the Japanese manufacturer Mazda between 1971 and 1978. Between 1978 and 1991, spanning two generations, Mazda sold the Savanna replacement as the Mazda Savanna RX-7 . Mazda exclusively used the Savanna nameplate in Japan. It was exported as the Mazda RX-3 in its first generation from 1971 to 1978, and as the Mazda RX-7 in its subsequent generations. For

232-837: A hybrid version of its Premacy compact minivan using a version of its signature rotary engine that can run on hydrogen or gasoline named the Mazda Premacy Hydrogen RE Hybrid . Despite plans to release it in 2008, as of 2010 the vehicle is in limited trials. In 2010, Toyota and Mazda announced a supply agreement for the hybrid technology used in Toyota's Prius model. Mazda is finding uses for biomaterials in its vehicles, including both plastics and fabrics made from corn starch, as it aims to become more environmentally-friendly. Mazda introduced some of these innovations (bioplastic internal consoles and bio-fabric seats) in its Mazda5 model at EcoInnovasia 2008, at

348-452: A 33.4-percent controlling interest in May 1996. In June 1996, Henry Wallace was appointed president, and he set about restructuring Mazda and setting it on a new strategic direction. He laid out a new direction for the brand including the design of the present Mazda marque; he laid out a new product plan to achieve synergies with Ford, and he launched Mazda's digital innovation program to speed up

464-498: A MazdaSpeed5), and other venues. Wankel engines have been banned for some time from international Formula One racing, as well as from United States midget racing , after Gene Angelillo won the North East Midget Racing Association championship in 1985 with a car powered by a 13B engine, and again in 1986 in a car powered by a 12A engine. The Cooper Tires Atlantic Championship powered by Mazda

580-576: A Wankel engine are thus mainly limited by tooth load on the synchronizing gears. Hardened steel gears are used for extended operation above 7,000 or 8,000   rpm. In practice, automotive Wankel engines are not operated at much higher output shaft speeds than reciprocating piston engines of similar output power. Wankel engines in auto racing are operated at speeds up to 10,000   rpm, but so are four-stroke reciprocating piston engines with relatively small displacement per cylinder. In aircraft, they are used conservatively, up to 6500 or 7500   rpm. In

696-405: A Wankel rotary engine, the chamber volume V k {\displaystyle V_{k}} is equivalent to the product of the rotor surface A k {\displaystyle A_{k}} and the rotor path s {\displaystyle s} . The rotor surface A k {\displaystyle A_{k}} is given by the rotor tips' path across

812-400: A Wankel rotary engine, the eccentric shaft must make three full rotations (1080°) per combustion chamber to complete all four phases of a four-stroke engine. Since a Wankel rotary engine has three combustion chambers, all four phases of a four-stroke engine are completed within one full rotation of the eccentric shaft (360°), and one power pulse is produced at each revolution of the shaft. This

928-399: A boundary layer from overheating working parts. The University of Florida proposed the use of heat pipes in an air-cooled Wankel to overcome this uneven heating of the block housing. Pre-heating of certain housing sections with exhaust gas improved performance and fuel economy, also reducing wear and emissions. The boundary layer shields and the oil film act as thermal insulation, leading to

1044-600: A decade of class wins from other Mazda prototypes, including the 757 and 767 . The Sigma MC74 powered by a Mazda 12A engine was the first engine and team from outside Western Europe or the United States to finish the entire 24 hours of the Le Mans race, in 1974. Mazda is also the most reliable finisher at Le Mans (with the exception of Honda , which has entered only three cars in only one year), with 67% of entries finishing. Mazda returned to prototype racing in 2005 with

1160-406: A fresh air supply to the exhaust port. It also proved that a Reed-valve in the intake port or ducts improved the low rpm and partial load performance of Wankel engines, by preventing blow-back of exhaust gas into the intake port and ducts, and reducing the misfire-inducing high EGR, at the cost of a slight loss of power at top rpm. Elasticity is improved with a greater rotor eccentricity, analogous to

1276-439: A glow-plug for the leading site spark plug improved low rpm, part load, specific fuel consumption by 7%, and emissions and idle. A later alternative solution to spark plug boss cooling was provided with a variable coolant velocity scheme for water-cooled rotaries, which has had widespread use, being patented by Curtiss-Wright, with the last-listed for better air-cooled engine spark plug boss cooling. These approaches did not require

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1392-431: A high incidence of sealing loss, both between the rotor and the housing and also between the various pieces making up the housing. Also, in earlier model Wankel engines, carbon particles could become trapped between the seal and the casing, jamming the engine and requiring a partial rebuild. It was common for very early Mazda engines to require rebuilding after 50,000 miles (80,000 km). Further sealing problems arose from

1508-441: A high-conductivity copper insert, but did not preclude its use. Ford tested a Wankel engine with the plugs placed in the side plates, instead of the usual placement in the housing working surface ( CA 1036073   , 1978). Wankel engines are capable of high-speed operation, meaning they do not necessarily need to produce high torque to produce high power. The positioning of the intake port and intake port closing greatly affect

1624-455: A hybrid drivetrain for even greater fuel economy. In the racing world, Mazda has had substantial success with both its signature Wankel-engine cars (in two-rotor, three-rotor, and four-rotor forms) as well as its piston-engine models. Mazda vehicles and engines compete in a wide variety of disciplines and series around the world. In 1991, Mazda became the first Japanese automaker to win the 24 Hours of Le Mans overall. Mazda's competition debut

1740-437: A hybrid drivetrain. Engine output is increased and emission levels are reduced. These technologies include high compression ratio gasoline engines (13.0 to 1), reduced compression diesel engines (14.0 to 1) with new 2-stage turbocharger design, highly efficient automatic transmissions, lighter weight manual transmissions, lightweight body designs and electric power steering . It is also possible to combine these technologies with

1856-486: A joint venture with Ford New Zealand known as Vehicle Assemblers of New Zealand (VANZ), while in South Africa, Ford's local subsidiary merged with Sigma Motor Corporation , which already assembled Mazdas in the country, to form Samcor , although the sharing of models proved unpopular with both Ford and Mazda customers. In other markets such as Australia, however, the 323 and 626 were always fully imported, with only

1972-430: A long history of motorsport involvement, winning the 24 Hours of Le Mans in 1991 with the rotary-powered Mazda 787B . In the past and present, Mazda has been engaged in alliances with other automakers. From 1974 until the late 2000s, Ford was a major shareholder of Mazda. Other partnerships include Toyota , Nissan , Isuzu , Suzuki and Kia . In 2023, it produced 1.1 million vehicles globally. The name Mazda

2088-423: A longer stroke in a reciprocating engine. Wankel engines operate better with a low-pressure exhaust system. Higher exhaust back pressure reduces mean effective pressure, more severely in peripheral intake port engines. The Mazda RX-8 Renesis engine improved performance by doubling the exhaust port area relative to earlier designs, and there have been studies of the effect of intake and exhaust piping configuration on

2204-412: A low temperature of the lubricating film (approximate maximum 200 °C or 390 °F on a water-cooled Wankel engine). This gives a more constant surface temperature. The temperature around the spark plug is about the same as in the combustion chamber of a reciprocating engine. With circumferential or axial flow cooling, the temperature difference remains tolerable. Problems arose during research in

2320-406: A more steady idle, because it helps to prevent blow-back of burned gases into the intake ducts, which cause "misfirings" caused by alternating cycles where the mixture ignites and fails to ignite. Peripheral porting (PP) gives the best mean effective pressure throughout the rpm range, but PP was also linked to worse idle stability and part-load performance. Early work by Toyota led to the addition of

2436-467: A number of different brands in the Japanese (and occasionally Australian) markets in the 1990s, including Autozam , Eunos , and ɛ̃fini . The motivation was brought on by market competition from other Japanese automakers efforts in offering vehicles at multiple Japanese dealership networks offered by Toyota , Nissan , and Honda . Mazda's implementation of brand diversification reflected a Japanese engineering philosophy, called Kansei engineering , which

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2552-531: A result of the poor efficiency, a Wankel engine with peripheral exhaust porting has a larger amount of unburnt hydrocarbons (HC) released into the exhaust. The exhaust is, however, relatively low in nitrogen oxide (NOx) emissions, because the combustion is slow, and temperatures are lower than in other engines, and also because of the Wankel engine's good exhaust gas recirculation (EGR) behavior. Carbon monoxide (CO) emissions of Wankel and Otto engines are about

2668-513: A rotary internal combustion engine with Felix Wankel, based upon Wankel's supercharger design for their motorcycle engines. Since Wankel was known as a "difficult colleague", the development work for the DKM was carried out at Wankel's private Lindau design bureau. According to John B. Hege, Wankel received help from his friend Ernst Höppner, who was a "brilliant engineer". The first working prototype, DKM 54 (see figure 2.), first ran on 1 February 1957, at

2784-498: A single-rotor Wankel engine produces the same average power as a V h {\displaystyle V_{h}} single-cylinder two-stroke engine , with the same average torque, with the shaft running at the same speed, operating the Otto cycles at triple the frequency. Richard Franz Ansdale, Wolf-Dieter Bensinger and Felix Wankel based their analogy on the number of cumulative expansion strokes per shaft revolution. In

2900-403: A stationary center shaft, the DKM engine was impractical. Wolf-Dieter Bensinger explicitly mentions that proper engine cooling cannot be achieved in a DKM engine, and argues that this is the reason why the DKM design had to be abandoned. NSU development chief engineer Walter Froede solved this problem by using Hanns-Dieter Paschke's design and converting the DKM into what would later be known as

3016-510: A symbol of the beginning of the East and the West civilization, but also a symbol of the automotive civilization and culture." The company's website further notes that the name also derives from the name of the company's founder, Jujiro Matsuda . The alternative proposed names mean "god" ( Sumera ) and "angel" ( Tenshi ); both indicate Matsuda's strong interest in human faith. The Mazda lettering

3132-456: A thermal reactor or catalyst converter may be used to reduce hydrocarbon and carbon monoxide from the exhaust. Mazda uses a dual ignition system with two spark plugs per chamber. This increases the power output and at the same time reduces HC emissions. At the same time, HC emissions can be lowered by reducing the pre-ignition of the T leading plug relative to the L trailing plug. This leads to internal afterburning and reduces HC emissions. On

3248-425: A thin dimensional galvanized chrome layer. This allowed Mazda to return to the 3mm and later even 2mm thick metal apex seals. Another early problem was the build-up of cracks in the stator surface near the plug hole, which was eliminated by installing the spark plugs in a separate metal insert/ copper sleeve in the housing instead of a plug being screwed directly into the block housing. Toyota found that substituting

3364-614: A trial basis 40-octane gasoline was produced by BV Aral, which was used in the Wankel DKM54 test engine with a compression ratio of 8:1; it ran without complaint. This upset the petrochemical industry in Europe, which had invested considerable sums of money in new plants for the production of higher quality gasoline. Direct injection stratified charge engines can be operated with fuels with particularly low octane numbers. Such as diesel fuel, which only has an octane number of ~25. As

3480-608: Is Mazda's biggest market, followed by China and Japan. Mazda's market share in the U.S. fell to a 10-year low of 1.7 percent in 2016. Mazda's brand loyalty was 39 percent in 2016, below the industry average of 53 percent. On October 24, 2022, Mazda decided to get rid of assets in Russia, with the company transferring a stake in a joint venture in Vladivostok to Sollers JSC for 1 euro. Mazda has conducted research in hydrogen-powered vehicles for several decades. Mazda has developed

3596-774: Is a North American open wheel racing series. It is the top level of the MAZDASPEED ladder, a driver development program which rewards season winners of one level with automatic rides at the next level. Since 2006, the Atlantic Championship has been run exclusively with Swift 016.a chassis powered by Mazda- Cosworth MZR 2300 cc (2.3L) DOHC inline-4 engines producing 300 bhp (224 kW). The cars are capable of speeds in excess of 175 mph (282 km/h). Formula Mazda features open wheel race cars with Mazda engines, adaptable to both oval tracks and road courses, on several levels of competition. Since 1991,

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3712-558: Is depicted in figure 7. Seals at the rotor's apices seal against the housing's periphery. The rotor moves in its rotating motion guided by gears and the eccentric output shaft, not being guided by the external chamber. The rotor does not make contact with the external engine housing. The force of expanded gas pressure on the rotor exerts pressure on the center of the eccentric part of the output shaft. All practical Wankel engines are four-cycle (i.e., four-stroke) engines. In theory, two-cycle engines are possible, but they are impractical because

3828-428: Is described in the thermodynamic disadvantages section , the early Wankel engines had poor fuel economy. This is caused by the Wankel engine's design of combustion chamber shape and huge surface area. The Wankel engine's design is, on the other hand, much less prone to engine knocking, which allows using low- octane fuels without reducing compression. NSU tested low octane gasoline at the suggestion of Felix Wankel. On

3944-440: Is different from a four-stroke piston engine, which needs to make two full rotations per combustion chamber to complete all four phases of a four-stroke engine. Thus, in a Wankel rotary engine, according to Bensinger, displacement ( V h {\displaystyle V_{h}} ) is: If power is to be derived from BMEP, the four-stroke engine formula applies: Eugen Wilhelm Huber, and Karl-Heinz Küttner counted all

4060-535: Is the dominant source of hydrocarbon at high speeds and leakage at low speeds. Using side-porting which enables closing the exhaust port around the top-dead center and reducing intake and exhaust overlap helps improving fuel consumption. Mazda Motor Mazda Motor Corporation ( マツダ株式会社 , Matsuda Kabushiki gaisha ) , also known as simply Mazda , is a Japanese multinational automotive manufacturer headquartered in Fuchū , Hiroshima , Japan. The company

4176-397: Is the number of chambers considered for each rotor and i {\displaystyle i} the number of rotors, then the total displacement is: If p m e {\displaystyle p_{me}} is the mean effective pressure , N {\displaystyle N} the shaft rotational speed and n c {\displaystyle n_{c}}

4292-474: The 24 Hours of Daytona , and drove the car back to New Jersey. The Cosmo placed 18th overall in a field of 72. The only modifications were racing brake pads, exhaust, and safety equipment. After substantial successes by the Mazda RX-2 and Mazda RX-3 , the Mazda RX-7 has won more IMSA races in its class than any other model of automobile, with its hundredth victory on September 2, 1990. Following that,

4408-521: The Mazda 121 sold in Europe and South Africa was, for a time, a variant of the Ford Fiesta built in plants in Europe and South Africa. Mazda also made an effort in the past to sell some of Ford's cars in Japan, mainly through its Autorama dealer group. Mazda also helped Ford develop the 1991 Explorer , which Mazda sold as the 2-door only Mazda Navajo from 1991 through 1994. However, Mazda's version

4524-676: The Queen Sirikit National Convention Center in Bangkok . Up to 30% of the interior parts in the Mazda5 are made of biomaterial components. SkyActiv technology is an umbrella name for a range of technologies used in certain new Mazda vehicles. These vehicles include the Mazda2/Demio , Mazda3/Axela , Mazda6/Atenza , and CX-5 . Together these technologies increase fuel economy to a level similar to

4640-470: The RX-3 and RX-4 lines for certain markets). After nine years of development, Mazda finally launched its new model in the U.S. in 1970. Mazda's rotary success continued until the onset of the 1973 oil crisis . As American buyers (as well as those in other nations) quickly turned to vehicles with better fuel efficiency, the relatively thirsty rotary-powered models began to fall out of favor. Combined with being

4756-606: The Xedos name was also associated with the Mazda Xedos 6 , the two models were in production from 1992 until 1997. The Xedos line was marketed under the Mazda brand, and used the Mazda badge from the corresponding years. This diversification stressed the product development groups at Mazda past its limits. Instead of having a half-dozen variations on any given platform , developers were asked to work on dozens of different models at

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4872-594: The 1950s and 1960s. For a while, engineers were faced with what they called "chatter marks" and "devil's scratch" in the inner epitrochoid surface, resulting in chipping of the chrome coating of the trochoidal surfaces. They discovered that the cause was the apex seals reaching a resonating vibration, and the problem was solved by reducing the thickness and weight of the apex seals as well as using more suitable materials. Scratches disappeared after introducing more compatible materials for seals and housing coatings. Yamamoto experimentally lightened apex seals with holes. Now, weight

4988-606: The 1960s, Mazda was inspired by the NSU Ro 80 and decided to put a major engineering effort into development of the Wankel rotary engine as a way of differentiating itself from other Japanese auto companies. The company formed a business relationship with German company NSU and began with the limited-production Cosmo Sport of 1967, and continuing to the present day with the Pro Mazda Championship , Mazda has become

5104-498: The 1960s. Starting in 1979 by expanding their 7 percent financial stake to 24.5%, Ford expanded an existing partnership with Mazda, resulting in various joint projects. The cooperation had begun in 1971 when the Mazda B-Series spawned a Ford Courier variant for North America, a version which was later offered in other markets as well. Mazda's Bongo and Titan cab-over trucks were sold with Ford badging in mainly Asia and

5220-791: The 1980s, Ford-badged Mazda products replaced much of their own European-sourced lineup, especially in the Asia-Pacific markets, with the Laser replacing the Escort and the Telstar replacing the Cortina . In some cases, such as New Zealand and South Africa , these were assembled alongside their Mazda-badged equivalents, the Mazda 323 (Familia) and 626 (Capella). Following the closure of its own assembly plant in New Zealand, Mazda established

5336-564: The 84 hour Nürburgring race with four Familias. Only one of these finished, taking fifth place. The first racing victory by a Wankel-engined car in the United States was in 1973, when Pat Bedard won an IMSA RS race at Lime Rock Park in a Mazda RX-2 . In 1976, Ray Walle, owner of Z&W Mazda, drove a Cosmo ( Mazda RX-5 ) from the dealership in Princeton, New Jersey, to Daytona, won the Touring Class Under 2.5 Liters at

5452-717: The American market ( Mazda North American Operations ) and was very successful there, going so far as to create the Mazda Rotary Pickup (based on the conventional piston-powered B-Series model) solely for North American buyers. To this day, Mazda remains the only automaker to have produced a Wankel-powered pickup truck. Additionally, it is also the only brand to have ever offered a rotary-powered bus (the Mazda Parkway, offered only in Japan) or station wagon (within

5568-550: The DKM engine were built; the design is described to have a displacement V h of 250 cm (equivalent to a working chamber volume V k of 125 cm ). The fourth unit built is said to have received several design changes, and eventually produced 29 PS (21 kW) at 17,000 rpm; it could reach speeds up to 22,000 rpm. One of the four engines built has been on static display at the Deutsches Museum Bonn (see figure. 2). Due to its complicated design with

5684-508: The KKM (see figure 5.). The KKM proved to be a much more practical engine, as it has easily accessible spark plugs, a simpler cooling design, and a conventional power take-off shaft. Wankel disliked Froede's KKM engine because of its inner rotor's eccentric motion, which was not a pure circular motion, as Wankel had intended. He remarked that his "race horse" was turned into a "plough horse". Wankel also complained that more stresses would be placed on

5800-460: The KKM type. Felix Wankel designed a rotary compressor in the 1920s, and received his first patent for a rotary type of engine in 1934. He realized that the triangular rotor of the rotary compressor could have intake and exhaust ports added producing an internal combustion engine. Eventually, in 1951, Wankel began working at German firm NSU Motorenwerke to design a rotary compressor as a supercharger for NSU's motorcycle engines. Wankel conceived

5916-488: The KKM ;502 was a powerful engine with decent potential, smooth operation, and low noise emissions at high engine speeds. It was a single-rotor PP engine with a displacement of 996 cm (61 in ), a rated power of 40 kW (54 hp) at 6,000   rpm and a BMEP of 1 MPa (145 lbf/in ). The Wankel engine has a spinning eccentric power take-off shaft, with a rotary piston riding on eccentrics on

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6032-510: The KKM's apex seals due to the eccentric hula-hoop motion of the rotor. NSU could not afford to finance developing both the DKM and the KKM, and eventually decided to drop the DKM in favor of the KKM, because the latter seemed to be the more practical design. Wankel obtained the US patent 2,988,065 on the KKM engine on 13 June 1961. Throughout the design phase of the KKM, Froede's engineering team had to solve problems such as repeated bearing seizures,

6148-587: The Laser and Telstar assembled locally. In Japan, the Laser and Telstar were also sold alongside their Mazda-badged brethren, but the Festiva was not sold as a Mazda 121 on the Japanese market. In North America, the Probe was built in a new Mazda company plant in Flat Rock, Michigan , along with the mainstream 626 sedan and a companion Mazda MX-6 sports coupe. Ford also lent Mazda some of its capacity when needed:

6264-547: The NSU research and development department Versuchsabteilung TX . It produced 21 PS (15 kW). Soon after that, a second prototype of the DKM was built. It had a working chamber volume V k of 125 cm and also produced 21 kW (29 PS) at 17,000   rpm. It could even reach speeds of up to 25,000   rpm. However, these engine speeds distorted the outer rotor's shape, thus proving impractical. According to Mazda Motors engineers and historians, four units of

6380-624: The Pacific region beginning in 1976. These included large and small efforts in all areas of the automotive landscape, most notably in the realm of pickup trucks and smaller cars. Mazda began supplying manual transaxles to Ford in the spring of 1980. Mazda's Familia platform was used for Ford models like the Laser and Escort beginning in 1980, while the Capella architecture found its way into Ford's Telstar sedan and Probe sports models. During

6496-607: The RX-7 won its class in the IMSA 24 Hours of Daytona race ten years in a row, starting in 1982. The RX-7 won the IMSA Grand Touring Under Two Liter (GTU) championship each year from 1980 through 1987, inclusive. In 1991, a four-rotor Mazda 787B (2622 cc actual, rated by FIA formula at 4708 cc) won the 24 Hours of Le Mans auto race outright. The 787B's triumph remains unparalleled, as it remains

6612-443: The Wankel engine run much smoother. This is because the Wankel engine has a lower moment of inertia and less excess torque area due to its more uniform torque delivery. For example, a two-rotor Wankel engine runs more than twice as smoothly as a four-cylinder piston engine. The eccentric output shaft of a Wankel engine also does not have the stress-related contours of a reciprocating piston engine's crankshaft. The maximum revolutions of

6728-467: The alliance between Ford and Mazda has been a very successful one, with Mazda saving perhaps $ 90 million a year in development costs and Ford "several times" that, and that a sale of its stake in Mazda would be a desperate measure. On November 18, 2008, Ford announced that it would sell a 20% stake in Mazda, reducing its stake to 13.4%, thus surrendering control of the company, which it held since 1996. The following day, Mazda announced that, as part of

6844-613: The average torque, with the shaft running at 2/3 the speed, operating the Otto cycles at the same frequency: Applying a 2/3 gear set to the output shaft of the three-cylinder (or a 3/2 one to the Wankel), the two are analogous from the thermodynamic and mechanical output point of view, as pointed out by Huber. NSU licensed the Wankel engine design to companies worldwide, in various forms, with many companies implementing continual improvements. In his 1973 book Rotationskolben-Verbrennungsmotoren , German engineer Wolf-Dieter Bensinger describes

6960-422: The axially closer side housings in the cooler intake lobe areas was dealt with by using an axial rotor pilot radially inboard of the oils seals, plus improved inertia oil cooling of the rotor interior (C-W US 3261542   , C. Jones, 5/8/63, US 3176915   , M. Bentele, C. Jones. A.H. Raye. 7/2/62), and slightly "crowned" apex seals (different height in the center and in the extremes of seal). As

7076-551: The beginning bore that name. The Mazda R360 was introduced in 1960, followed by the Mazda Carol in 1962 and were sold at a specific retail dealership that sold passenger cars called "Mazda Auto Store" whereas commercial products were sold at "Mazda Store". As Mazda continued to offer passenger cars like the Savanna , Familia , Luce , Cosmo and Capella , they were added to the "Mazda Auto Store" network only. Beginning in

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7192-407: The chambers, since each one operates its own thermodynamic cycle. So y = 3 {\displaystyle y=3} and n c = 3 {\displaystyle n_{c}=3} : With these values, a single-rotor Wankel engine produces the same average power as a V h {\displaystyle V_{h}} three-cylinder four-stroke engine, with 3/2 of

7308-435: The company had not totally turned its back on piston engines, as it continued to produce a variety of four-cylinder models throughout the 1970s. The smaller Familia line in particular became very important to Mazda's worldwide sales after 1973, as did the somewhat larger Capella series. Mazda refocused its efforts and made the rotary engine a choice for the sporting motorist rather than a mainstream powerplant. Starting with

7424-600: The concept of the small sports car after its decline in the late 1970s. From 1974 to 2015, Mazda had a partnership with the Ford Motor Company , which acquired a 24.5% stake in 1979, upped to a 33.4% ownership of Mazda in May 1995. Under the administration of Alan Mulally , Ford gradually divested its stake in Mazda from 2008 to 2015, with Ford holding 2.1% of Mazda stock as of 2014 and severing most production as well as development ties. This partnership with Ford began owing to Mazda's financial difficulties during

7540-479: The deal, it was buying back 6.8% of its shares from Ford for about US$ 185 million while the rest would be acquired by business partners of the company. It was also reported that Hisakazu Imaki would be stepping down as chief executive, to be replaced by Takashi Yamanouchi . On November 18, 2010, Ford reduced its stake further to 3%, citing the reduction of ownership would allow greater flexibility to pursue growth in emerging markets, and Sumitomo Mitsui Financial Group

7656-438: The design and marketing of the second generation of Savanna. The subsequent two generations, released in 1978 and 1985 respectively, fitted the rotary engines to a unique coupe body that sold internationally as the Mazda RX-7 . The rotary engine had financial advantages to Japanese consumers in that the engine displacement remained below 1.5 litres, a significant determination when paying the Japanese annual road tax which kept

7772-426: The design of a triangular rotor in the compressor. With the assistance of Prof. Othmar Baier  [ de ] from Stuttgart University of Applied Sciences, the concept was defined mathematically. The supercharger he designed was used for one of NSU's 50 cm one-cylinder two-stroke engines. The engine produced a power output of 13.5 PS (10 kW) at 12,000   rpm. In 1954, NSU agreed to develop

7888-642: The development of new products. At the same time, he started taking control of overseas distributors, rationalized dealerships and manufacturing facilities, and driving much-needed efficiencies and cost reductions in Mazda's operations. Much of his early work put Mazda back into profitability and laid the foundations for future success. Wallace was succeeded by James Miller in November 1997, followed in December 1999 by Ford executive Mark Fields , who has been credited with expanding Mazda's new product lineup and leading

8004-448: The early days, unique, dedicated production machines had to be built for different housing dimensional arrangements. However, patented designs such as U.S. patent 3,824,746 , G. J. Watt, 1974, for a "Wankel Engine Cylinder Generating Machine", U.S. patent 3,916,738 , "Apparatus for machining and/or treatment of trochoidal surfaces" and U.S. patent 3,964,367 , "Device for machining trochoidal inner walls", and others, solved

8120-416: The engine's torque production. Early closing of the intake port increases low-end torque, but reduces high-end torque (and thus power). In contrast, late closing of the intake port reduces low-end torque while increasing torque at high engine speeds, thus resulting in more power at higher engine speeds. A peripheral intake port gives the highest mean effective pressure ; however, side intake porting produces

8236-431: The engine. While this puts great demands on the materials used, the simplicity of the Wankel makes it easier to use alternative materials, such as exotic alloys and ceramics . A commonplace method is, for engine housings made of aluminum, to use a spurted molybdenum layer on the engine housing for the combustion chamber area, and a spurted steel layer elsewhere. Engine housings cast from iron can be induction-brazed to make

8352-421: The experience gained, from carbon alloys, to steel, ferritic stainless , Ferro-TiC, and other materials. The combination of housing plating and the apex and side seal materials was determined experimentally, to obtain the best duration of both seals and housing cover. For the shaft, steel alloys with little deformation on load are preferred, the use of Maraging steel has been proposed for this. Leaded petrol fuel

8468-463: The factor that controls the amount of unburnt hydrocarbons in the exhaust is the rotor surface temperature, with higher temperatures resulting in fewer hydrocarbons in the exhaust. Curtiss-Wright widened the rotor, keeping the rest of engine's architecture unchanged, thus reducing friction losses and increasing displacement and power output. The limiting factor for this widening was mechanical, especially shaft deflection at high rotative speeds. Quenching

8584-404: The farthest, and a {\displaystyle a} as the shortest parallel transfer of the rotor and the inner housing and assuming that R 1 = R + a {\displaystyle R_{1}=R+a} and R 2 = R + a ′ {\displaystyle R_{2}=R+a'} . Then, Including the parallel transfers of the rotor and

8700-554: The first Miller cycle engine for automotive use in the Millenia luxury sedan of 1995. Though the Millenia (and its Miller-type V6 engine) were discontinued in 2002, the company introduced a much smaller Miller-cycle four-cylinder engine for use in its Demio in 2008. Further financial difficulties at Mazda during the 1990s ( partly caused by losses related to the 1997 Asian financial crisis ) caused Ford to increase its stake to

8816-529: The following licensees, in chronological order, which is confirmed by John B. Hege: In 1961, the Soviet research organizations of NATI, NAMI, and VNIImotoprom began developing a Wankel engine. Eventually, in 1974, development was transferred to a special design bureau at the AvtoVAZ plant. John B. Hege argues that no license was issued to any Soviet car manufacturer. Felix Wankel managed to overcome most of

8932-449: The inner housing provides sufficient accuracy for determining chamber volume. Different approaches have been used over time to evaluate the total displacement of a Wankel engine in relation to a reciprocating engine: considering only one, two, or all three chambers. Part of this dispute was because of Europe vehicle taxation being dependent on engine displacement, as reported by Karl Ludvigsen . If y {\displaystyle y}

9048-536: The intake gas and the exhaust gas cannot be properly separated. The operating principle is similar to the Otto operating principle; the Diesel operating principle with its compression ignition cannot be used in a practical Wankel engine. Therefore, Wankel engines typically have a high-voltage spark ignition system. In a Wankel engine, one side of the triangular rotor completes the four-stage Otto cycle of intake, compression, expansion, and exhaust each revolution of

9164-929: The introduction of the Courage C65 LMP2 car at the American Le Mans Series race at Road Atlanta . This prototype racer uses the Renesis Wankel from the RX-8. Mazdas have also enjoyed substantial success in World Land Speed competition, SCCA competition, drag racing , pro rally competition (the Familia appeared in the WRC several times during the late '80s and early '90s), the One Lap of America race (winning SUV & truck in

9280-552: The introduction of the Mazda-Go auto rickshaw . The name Mazda came into existence with the production of the company's first three-wheeled trucks. Other candidates for a model name included Sumera-Go , Tenshi-Go , and more. Officially, the company states: Mazda comes from Ahura Mazda , the god of harmony, intelligence and wisdom from the earliest civilization in West Asia . Key members of Toyo Kogyo interpreted Mazda as

9396-416: The least-efficient automaker in Japan (in terms of productivity), inability to adjust to excess inventory and over-reliance on the U.S. market, the company suffered a huge loss in 1975. An already heavily indebted Toyo Kogyo was on the verge of bankruptcy and was only saved through the intervention of Sumitomo keiretsu group, namely Sumitomo Bank , and the company's subcontractors and distributors. However,

9512-555: The lightweight RX-7 in 1978 and continuing with the modern RX-8 , Mazda has continued its dedication to this unique powerplant. This switch in focus also resulted in the development of another lightweight sports car, the piston-powered Mazda MX-5 Miata (sold as the Eunos and later Mazda Roadster in Japan), inspired by the concept ' jinba ittai '. Introduced in 1989 to worldwide acclaim, the Roadster has been widely credited with reviving

9628-414: The material suited for withstanding combustion heat stress. Among the alloys cited for Wankel housing use are A-132, Inconel 625, and 356 treated to T6 hardness. Several materials have been used for plating the housing working surface, Nikasil being one. Citroën, Daimler-Benz, Ford, A P Grazen, and others applied for patents in this field. For the apex seals, the choice of materials has evolved along with

9744-430: The number of shaft revolutions needed to complete a cycle ( N / n c {\displaystyle N/n_{c}} is the frequency of the thermodynamic cycle), then the total power output is: Kenichi Yamamoto and Walter G. Froede placed y = 1 {\displaystyle y=1} and n c = 1 {\displaystyle n_{c}=1} : With these values,

9860-468: The obligation affordable to most buyers, while having more power than the traditional inline engines. Wankel rotary engine In its basic gasoline fuelled form, the Wankel engine has lower thermal efficiency and higher exhaust emissions relative to the four-stroke reciprocating piston engine. The thermal inefficiency has restricted the engine to limited use since its introduction in the 1960s. However, many disadvantages have mainly been overcome over

9976-546: The oil flow inside the engine, and the engine cooling. The first fully functioning KKM engine, the KKM 125, weighing in at only 17 kg (37.5 lb) displaced 125 cm and produced 26 PS (19 kW) at 11,000   rpm. Its first run was on 1 July 1958. In 1963, NSU produced the first series-production Wankel engine for a car, the KKM 502 (see Figure 6.). It was used in the NSU Spider sports car, of which about 2,000 were made. Despite its "teething troubles",

10092-456: The only non-piston-engined car ever to win at Le Mans, and Mazda is the first Japanese brand to have won overall at Le Mans. This led to a ban on rotary engines in the Le Mans race starting in 1992, which has since been rescinded. After the 1991 race, the winning engine was publicly dismantled for internal examination, which demonstrated that despite 24 hours of extremely hard use it had accumulated very little wear. The Le Mans win in 1991 followed

10208-595: The original 1971 version of Savanna, Mazda fitted its 10A rotary engine to the Mazda Grand Familia to create a separately marketed product sold in coupé, sedan, and station wagon guises. The engine was upgraded to the larger 12A rotary in the GT model introduced in September 1972, and eventually this became the standard engine across the entire range. Coupé sales accounted for over half of total sales, influencing

10324-506: The other hand, the same ignition timing of L and T leads to a higher energy conversion. Hydrocarbons adhering to the combustion chamber wall are expelled into the exhaust at the peripheral outlet. Mazda used 3 spark plugs in their R26B engine per chamber. The third spark plug ignites the mixture in the trailing side before the squish is generated, causing the mixture to burn completely and, also speeding up flame propagation, which improves fuel consumption. According to Curtiss-Wright research,

10440-430: The performance of Wankel engines. Side intake ports (as used in Mazda's Renesis engine) were first proposed by Hanns-Dieter Paschke in the late 1950s. Paschke predicted that precisely calculated intake ports and intake manifolds could make a side port engine as powerful as a PP engine. As formerly described, the Wankel engine is affected by unequal thermal expansion due to the four cycles taking place in fixed places of

10556-463: The problem. Wankel engines have a problem not found in reciprocating piston four-stroke engines in that the block housing has intake, compression, combustion, and exhaust occurring at fixed locations around the housing. This causes a very uneven thermal load on the rotor housing. In contrast, four-stroke reciprocating engines perform these four strokes in one chamber, so that extremes of "freezing" intake and "flaming" exhaust are averaged and shielded by

10672-421: The problems that made prior attempts to perfect the rotary engines fail, by developing a configuration with vane seals having a tip radius equal to the amount of "oversize" of the rotor housing form, relative to the theoretical epitrochoid, to minimize radial apex seal motion plus introducing a cylindrical gas-loaded apex pin which abutted all sealing elements to seal around the three planes at each rotor apex. In

10788-486: The proceeds were used to build an auto plant in Salamanca , Mexico . The Mexican plant was built jointly by the company and Sumitomo Corporation . In May 2015, the company signed an agreement with Toyota to form a "long-term partnership", that would, among others, see Mazda supply Toyota with fuel-efficient SkyActiv gasoline and diesel engine technology in exchange for hydrogen fuel cell systems. Mazda tried using

10904-600: The professionally organized Pro Mazda Championship has been the most popular format for sponsors, spectators, and upward bound drivers. It is the second-highest level on the aforementioned Mazdaspeed driver development ladder. Engines for the Star Mazda series are all built by one engine builder, certified to produce the prescribed power, and sealed to discourage tampering. They are in a relatively mild state of racing tune, so that they are extremely reliable and can go years between motor rebuilds. Spec Miata has become one of

11020-429: The rotor (equivalent to three shaft revolutions, see Figure 8.). The shape of the rotor between the fixed apexes is to minimize the volume of the geometric combustion chamber and maximize the compression ratio , respectively. As the rotor has three sides, this gives three power pulses per revolution of the rotor. Wankel engines have a much lower degree of irregularity relative to a reciprocating piston engine, making

11136-410: The rotor housing and determined by the generating radius R {\displaystyle R} , the rotor width B {\displaystyle B} , and the parallel transfers of the rotor and the inner housing a {\displaystyle a} . Since the rotor has a trochoid ("triangular") shape, the sine of 60 degrees describes the interval at which the rotors get closest to

11252-443: The rotor housing. Therefore, The rotor path s {\displaystyle s} may be integrated via the eccentricity e {\displaystyle e} as follows: Therefore, For convenience, a {\displaystyle a} may be omitted because it is difficult to determine and small: A different approach to this is introducing a ′ {\displaystyle a'} as

11368-514: The same time. Consumers were confused as well by the explosion of similar new models. This selective marketing experiment was ended in the mid-1990s due to economic conditions, largely attributed to the collapse of the Japanese asset price bubble in 1991. Traditionally, Mazda has always been led by an executive leader known as the President and CEO. As of January 2022 , the United States

11484-407: The same. The Wankel engine has a significantly higher (Δt K >100 K) exhaust gas temperature than an Otto engine, especially under low and medium load conditions. This is because of the higher combustion frequency and slower combustion. Exhaust gas temperatures can exceed 1300 K under high load at engine speeds of 6000 rpm . To improve the exhaust gas behavior of the Wankel engine,

11600-406: The shaft in a hula-hoop fashion. The Wankel is a 2:3 type of rotary engine, i.e., its housing's inner side resembles a two lobes oval-like epitrochoid (equivalent to a peritrochoid),. In contrast, its rotary piston has a three vertices trochoid shape (similar to a Reuleaux triangle ). Thus, the Wankel engine's rotor constantly forms three moving working chambers. The Wankel engine's basic geometry

11716-423: The sole manufacturer of Wankel-type engines for the automotive market, mainly by way of attrition. (NSU and Citroën both gave up on the design during the 1970s, and prototype Corvette efforts by General Motors never made it to production.) This effort to bring attention to itself apparently helped, as Mazda rapidly began to export its vehicles. Both piston-powered and rotary-powered models made their way around

11832-422: The succeeding decades as the production of road-going vehicles progressed. The advantages of compact design, smoothness, lower weight, and fewer parts over the reciprocating piston internal combustion engines make the Wankel engine suited for applications such as chainsaws , auxiliary power units (APUs), loitering munitions , aircraft , jet skis , snowmobiles , and range extenders in cars . The Wankel engine

11948-426: The turnaround during the early 2000s. Ford's increased influence during the 1990s allowed Mazda to claim another distinction in history, having maintained the first foreign-born head of a Japanese car company, Henry Wallace. Amid the world financial crisis in the fall of 2008, reports emerged that Ford was contemplating a sale of its stake in Mazda as a way of streamlining its asset base. BusinessWeek explained

12064-512: The uneven thermal distribution within the housings causing distortion and loss of sealing and compression. This thermal distortion also caused uneven wear between the apex seal and the rotor housing, evident on higher mileage engines. The problem was exacerbated when the engine was stressed before reaching operating temperature . However, Mazda Wankel engines solved these initial problems. Current engines have nearly 100 seal-related parts. The problem of clearance for hot rotor apexes passing between

12180-568: The world. The rotary models quickly became popular for their combination of good power and light weight when compared to piston-engined competitors that required heavier V6 or V8 engines to produce the same power. The R100 and the RX series ( RX-2 , RX-3 , and RX-4 ) led the company's export efforts. During 1968, Mazda started formal operations in Canada (MazdaCanada) although Mazdas were seen in Canada as early as 1959. In 1970, Mazda formally entered

12296-579: Was also used to power motorcycles and racing cars . The Wankel engine is a type of rotary piston engine and exists in two primary forms, the Drehkolbenmotor (DKM, "rotary piston engine"), designed by Felix Wankel (see Figure 2.) and the Kreiskolbenmotor (KKM, "circuitous piston engine"), designed by Hanns-Dieter Paschke (see Figure 3.), of which only the latter has left the prototype stage. Thus, all production Wankel engines are of

12412-471: Was believed to become its largest shareholder. Ford and Mazda remained strategic partners through joint ventures and exchanges of technological information. On September 30, 2015, when Ford's shares had sunk to a little over 2% due to stock dilution , Ford sold its remaining shares in Mazda. In 2011, Mazda raised more than 150 billion yen (US$ 1.9 billion) in a record share sale to replenish capital, as it suffered its biggest annual loss in 11 years. Part of

12528-792: Was derived from Ahura Mazda , the god of harmony, intelligence and wisdom in Zoroastrianism , as well as from the surname of the founder, Matsuda . Mazda began as the Toyo Cork Kogyo Co., Ltd, as a cork -making factory founded in Hiroshima , Japan, January 30, 1920. Toyo Cork Kogyo renamed itself to Toyo Kogyo Co., Ltd. in 1927. In the late 1920s the company had to be saved from bankruptcy by Hiroshima Saving Bank and other business leaders in Hiroshima. In 1931, Toyo Kogyo moved from manufacturing machine tools to vehicles with

12644-516: Was founded on January 30, 1920, as Toyo Cork Kogyo Co., Ltd., a cork-making factory, by Jujiro Matsuda . The company then acquired Abemaki Tree Cork Company. It changed its name to Toyo Kogyo Co., Ltd. in 1927 and started producing vehicles in 1931. Mazda is known for its innovative technologies, such as the Wankel engine , the SkyActiv platform, and the Kodo Design language. It also has

12760-456: Was identified as the main cause. Mazda then used aluminum-impregnated carbon apex seals in their early production engines. NSU used carbon antimony-impregnated apex seals against chrome. NSU developed ELNISIL coating to production maturity and returned to a metal sealing strip for the RO80. Mazda continued to use chrome, but provided the aluminum housing with a steel jacket, which was then coated with

12876-701: Was on October 20, 1968, when two Mazda Cosmo Sport 110S coupes entered the 84-hour Marathon de la Route ultra-endurance race at the Nürburgring , one finishing in fourth place and the other breaking an axle after 81 hours. The next year, Mazda raced Mazda Familia R100 M10A coupes. After winning the Singapore Grand Prix in April 1969 and coming in fifth and sixth in the Spa 24 Hours (beaten only by Porsche 911s ), on October 19, 1969, Mazda again entered

12992-573: Was the predominant type available in the first years of the Wankel engine's development. Lead is a solid lubricant, and leaded petrol is designed to reduce the wearing of seals and housings. The first engines had the oil supply calculated with consideration of petrol's lubricating qualities. As leaded petrol was being phased out, Wankel engines needed an increased mix of oil in the petrol to provide lubrication to critical engine parts. An SAE paper by David Garside extensively described Norton's choices of materials and cooling fins. Early engine designs had

13108-683: Was to begin selling in late 1993. The initial Amati range would have included the Amati 500 (which became the Eunos 800 in Japan and Australia, Mazda Millenia in the U.S., and Mazda Xedos 9 in Europe), a rebadged version of the Mazda Cosmo and the Amati 1000 (a rear-wheel drive V12 competitor to the Lexus LS400 ). The Amati brand was eventually scrapped before any cars hit the market. In Europe,

13224-611: Was unsuccessful, while the Ford (available from the start as a 4-door or 2-door model) instantly became the best-selling sport-utility vehicle in the United States and kept that title for over a decade. Mazda has used Ford's Ranger pickup as the basis for its North American–market B-Series trucks, starting in 1994 and continuing through 2010, when Mazda discontinued the B-Series trucks to North America. Following its long-held fascination with alternative engine technology, Mazda introduced

13340-712: Was used as an advertising slogan in North America. One of the most niche sub-brands was M2 , used on three rare variants of the Eunos Roadster (the M2-1001, M2-1002 and M2-1028) and one of the Autozam AZ-1 (M2-1015). M2 even had its own avant-garde company headquarters, but was shut down after a very short period of operation. In early 1992, Mazda planned to release a luxury brand, Amati , to challenge Acura , Infiniti , and Lexus in North America, which

13456-532: Was used in combination with the corporate emblem of Mitsubishi Motors , which was responsible for sales, to produce the Toyo Kogyo three-wheeled truck registered trademark. Toyo Kogyo produced weapons for the Japanese military throughout the Second World War, most notably the series 30 through 35 Type 99 rifle . The company formally adopted the Mazda name in 1984, though every automobile sold from

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