Variable Compression Ratio
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Variable Compression Ratio
Variable compression ratio (VCR) is a technology to adjust the compression ratio of an internal combustion engine while the engine is in operation. This is done to increase fuel efficiency while under varying loads. Variable compression engines allow the volume above the piston at Dead centre (engineering), top dead centre to be changed. Higher loads require lower ratios to increase power, while lower loads need higher ratios to increase efficiency, i.e. to lower fuel consumption. For automotive use this needs to be done as the engine is running in response to the load and driving demands. The 2019 Infiniti Infiniti QX50, QX50 is the first commercially available vehicle that uses a variable compression ratio engine. Advantages Gasoline engines have a limit on the maximum pressure during the compression stroke, after which the fuel/air mixture detonates rather than burns. To achieve higher power outputs at the same speed, more fuel must be burned and therefore more air is needed. T ...
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Compression Ratio
The compression ratio is the ratio between the volume of the cylinder and combustion chamber in an internal combustion engine at their maximum and minimum values. A fundamental specification for such engines, it is measured two ways: the static compression ratio, calculated based on the relative volumes of the combustion chamber and the cylinder when the piston is at the bottom of its stroke, and the volume of the combustion chamber when the piston is at the top of its stroke. The dynamic compression ratio is a more advanced calculation which also takes into account gasses entering and exiting the cylinder during the compression phase. Effect and typical ratios A high compression ratio is desirable because it allows an engine to extract more mechanical energy from a given mass of air–fuel mixture due to its higher thermal efficiency. This occurs because internal combustion engines are heat engines, and higher compression ratios permit the same combustion temperature to ...
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Combustion Chamber
A combustion chamber is part of an internal combustion engine in which the fuel/air mix is burned. For steam engines, the term has also been used for an extension of the firebox which is used to allow a more complete combustion process. Internal combustion engines In an internal combustion engine, the pressure caused by the burning air/fuel mixture applies direct force to part of the engine (e.g. for a piston engine, the force is applied to the top of the piston), which converts the gas pressure into mechanical energy (often in the form of a rotating output shaft). This contrasts an external combustion engine, where the combustion takes place in a separate part of the engine to where the gas pressure is converted into mechanical energy. Spark-ignition engines In spark ignition engines, such as petrol (gasoline) engines, the combustion chamber is usually located in the cylinder head. The engines are often designed such that the bottom of combustion chamber is roughly in li ...
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Diesel Engine
The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is a so-called compression-ignition engine (CI engine). This contrasts with engines using spark plug-ignition of the air-fuel mixture, such as a petrol engine (gasoline engine) or a gas engine (using a gaseous fuel like natural gas or liquefied petroleum gas). Diesel engines work by compressing only air, or air plus residual combustion gases from the exhaust (known as exhaust gas recirculation (EGR)). Air is inducted into the chamber during the intake stroke, and compressed during the compression stroke. This increases the air temperature inside the cylinder to such a high degree that atomised diesel fuel injected into the combustion chamber ignites. With the fuel being injected into the air just before combustion, the dispersion of the fuel is une ...
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Petrol
Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic compounds obtained by the fractional distillation of petroleum, enhanced with a variety of additives. On average, U.S. refineries produce, from a barrel of crude oil, about 19 to 20 gallons of gasoline; 11 to 13 gallons of distillate fuel (most of which is sold as diesel fuel); and 3 to 4 gallons of jet fuel. The product ratio depends on the processing in an oil refinery and the crude oil assay. A barrel of oil is defined as holding 42 US gallons, which is about 159 liters or 35 imperial gallons. The characteristic of a particular gasoline blend to resist igniting too early (which causes knocking and reduces efficiency in reciprocating engines) is measured by its octane rating, which is produced in several grades. Tetraethyl lead and other ...
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Saab Variable Compression Engine
The Saab Variable Compression engine was a development project of Saab Automobile, for which it won an award both in 2000 and 2001. In a normal internal combustion engine, because cylinder bore diameter, piston stroke length and combustion chamber volume are almost always constant, the compression ratio (CR) for a given engine is almost always constant. One exception is the experimental Saab Variable Compression (SVC) engine, designed for the Saab 9-5. This engine uses a technique that dynamically alters the volume of the combustion chamber, thus changing the compression ratio. To alter the combustion chamber volume, the SVC 'lowers' the cylinder head closer to the crankshaft. It does this by replacing the typical one-part engine block with a two-part block, with the crankshaft in the lower block and the cylinders in the upper portion. The two blocks are hinged together at one side. By pivoting the upper block around the hinge point, the volume of the combustion chamber can be mo ...
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Schema MCE5
The word schema comes from the Greek word ('), which means ''shape'', or more generally, ''plan''. The plural is ('). In English, both ''schemas'' and ''schemata'' are used as plural forms. Schema may refer to: Science and technology * SCHEMA (bioinformatics), an algorithm used in protein engineering * Schema (genetic algorithms), a set of programs or bit strings that have some genotypic similarity * Schema.org, a web markup vocabulary * Schema (logic) ** Axiom schema, in formal logic * Image schema, a recurring pattern of spatial sensory experience * Database schema * XML schema Other * Body schema, a neural representation of one's own bodily posture * Galant Schemata, stock phrases in Galant music * Schema (Kant), in philosophy * Schema (psychology), a mental set or representation * Schema Records, a jazz record label in Milan, Italy *, a solemn vow of asceticism of a monk in Orthodox monasticism ** Great Schema, the highest degree of Orthodox monasticism * ''Schema'' (fly) ...
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Renault
Groupe Renault ( , , , also known as the Renault Group in English; legally Renault S.A.) is a French multinational automobile manufacturer established in 1899. The company produces a range of cars and vans, and in the past has manufactured trucks, tractors, tanks, buses/coaches, aircraft and aircraft engines, and autorail vehicles. According to the Organisation Internationale des Constructeurs d'Automobiles, in 2016 Renault was the ninth biggest automaker in the world by production volume. By 2017, the Renault–Nissan–Mitsubishi Alliance had become the world's biggest seller of light vehicles. Headquartered in Boulogne-Billancourt, near Paris, the Renault group is made up of the namesake Renault marque and subsidiaries, Alpine, Renault Sport (Gordini), Automobile Dacia from Romania, and Renault Samsung Motors from South Korea. Renault has a 43.4% stake with several votes in Nissan of Japan, and used to have a 1.55% stake in Daimler AG of Germany, it was sold off in ...
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Citroën
Citroën () is a French automobile brand. The "Automobiles Citroën" manufacturing company was founded in March 1919 by André Citroën. Citroën is owned by Stellantis since 2021 and previously was part of the PSA Group after Peugeot acquired 89.95% share in 1976. Citroën's head office is located in the Stellantis Poissy Plant in Saint-Ouen-sur-Seine since 2021 (previously in Rueil-Malmaison) and its offices studies and research in Vélizy-Villacoublay, Poissy (CEMR), Carrières-sous-Poissy and Sochaux-Montbéliard. In 1934, the firm established its reputation for innovative technology with the Citroën Traction Avant, Traction Avant. This was the world's first car to be mass-produced with front-wheel drive, four-wheel independent suspension, as well as unibody construction, omitting a separate chassis, and instead using the body of the car itself as its main load-bearing structure. In 1954, they produced the world's first hydropneumatic self-levelling suspension system then, ...
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Peugeot
Peugeot (, , ) is a French brand of automobiles owned by Stellantis. The family business that preceded the current Peugeot companies was founded in 1810, with a steel foundry that soon started making hand tools and kitchen equipment, and then bicycles. On 20 November 1858, Émile Peugeot applied for the lion trademark. Armand Peugeot (1849–1915) built the company's first car steam tricycle, in collaboration with Léon Serpollet in 1889; this was followed in 1890 by an internal combustion car with a Panhard- Daimler engine. The Peugeot company and family are originally from Sochaux. Peugeot retains a large manufacturing plant and Peugeot museum there. In February 2014, the shareholders agreed to a recapitalisation plan for the PSA Group, in which Dongfeng Motors and the French government each bought a 14% stake in the company. Peugeot has received many international awards for its vehicles, including six European Car of the Year awards. Peugeot has been involved suc ...
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Volvo
The Volvo Group ( sv, Volvokoncernen; legally Aktiebolaget Volvo, shortened to AB Volvo, stylized as VOLVO) is a Swedish multinational manufacturing corporation headquartered in Gothenburg. While its core activity is the production, distribution and sale of trucks, buses and construction equipment, Volvo also supplies marine and industrial drive systems and financial services. In 2016, it was the world's second-largest manufacturer of heavy-duty trucks. Automobile manufacturer Volvo Cars, also based in Gothenburg, was part of AB Volvo until 1999, when it was sold to the Ford Motor Company. Since 2010 Volvo Cars has been owned by the automotive company Geely Holding Group. Both AB Volvo and Volvo Cars share the Volvo logo and cooperate in running the Volvo Museum in Sweden. The corporation was first listed on the Stockholm Stock Exchange in 1935, and was on the NASDAQ indices from 1985 to 2007. Volvo was established in 1915 as a subsidiary of SKF, a ball bearing manufacturer; ...
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Nissan Motors
, trading as Nissan Motor Corporation and often shortened to Nissan, is a Japanese multinational automobile manufacturer headquartered in Nishi-ku, Yokohama, Japan. The company sells its vehicles under the Nissan, Infiniti, and Datsun brands, with in-house performance tuning products (including cars) labelled Nismo. The company traces back to the beginnings of the 20th century, with the Nissan ''zaibatsu'', now called Nissan Group. Since 1999, Nissan has been part of the Renault–Nissan–Mitsubishi Alliance (Mitsubishi joining in 2016), a partnership between Nissan and Mitsubishi Motors of Japan, with Renault of France. , Renault holds a 43.4% voting stake in Nissan, while Nissan holds a 15% non-voting stake in Renault. Since October 2016 Nissan has held a 34% controlling stake in Mitsubishi Motors. In 2013, Nissan was the sixth largest automaker in the world, after Toyota, General Motors, Volkswagen Group, Hyundai Motor Group, and Ford. In 2014, Nissan was the largest car ...
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Saab Automobile
Saab Automobile AB () is a defunct automotive industry, car manufacturer that was founded in Sweden in 1945 when its parent company, Saab AB, began a project to design a small automobile. The first production model, the Saab 92, was launched in 1949. In 1968 the parent company merged with Scania-Vabis, and ten years later the Saab 900 was launched, in time becoming Saab's best-selling model. In the mid-1980s the new Saab 9000 model also appeared. In 1989, the automobile division of Saab-Scania was restructured into an independent company, Saab Automobile AB. The American manufacturer General Motors (GM) took 50 percent ownership. Two well-known models to come out of this period were the Saab 9-3 and the Saab 9-5. Then in 2000, GM exercised its option to acquire the remaining 50 percent. In 2010 GM sold Saab Automobile AB to the Dutch automobile manufacturer Spyker Cars N.V. After many years establishing a sound engineering reputation and ultimately a luxury car, luxury price t ...
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