A flat engine is an internal combustion engine The internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidiser in a combustion chamber. In an internal combustion engine the expansion of the high temperature and pressure gases, that are produced by the combustion, directly apply force to a movable component of the engine, such as the pistons or turbine with multiple pistons that all move in the horizontal plane. The most popular and significant layout has cylinders A cylinder is the central working part of a reciprocating engine, the space in which a piston travels. Multiple cylinders are commonly arranged side by side in a bank, or engine block, which is typically cast from aluminum or cast iron before precision features are machined into it. The cylinders may then be lined with sleeves or liners of some arranged in two banks on either side of a single crankshaft The crankshaft, sometimes casually abbreviated to crank, is the part of an engine which translates reciprocating linear piston motion into rotation. To convert the reciprocating motion into rotation, the crankshaft has "crank throws" or "crankpins", additional bearing surfaces whose axis is offset from that of the crank, to, generally known as "boxers". There is a widely-used but technologically less significant form consisting of a straight engine Usually found in 4- and 6-cylinder configurations, the straight engine is an internal-combustion engine with all cylinders aligned in one row, with no or only minimal offset with two, three, four or more cylinders canted 90 degrees into the horizontal plane.
The concept of the boxer was patented A patent is a set of exclusive rights granted by a state to an inventor or his assignee for a limited period of time in exchange for a disclosure of an invention in 1896 by engineer Karl Benz Karl Friedrich Benz, sometimes spelled as Carl, was a German engine designer and automobile engineer, generally regarded as the inventor of the gasoline-powered automobile and pioneering founder of the automobile manufacturer, Mercedes-Benz. Other German contemporaries, Gottlieb Daimler and Wilhelm Maybach working as partners, also worked on, eight years after he started producing the world's first successful cars An automobile or motor car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor. Most definitions of the term specify that automobiles are designed to run primarily on roads, to have seating for one to eight people, to typically have four wheels, and to be constructed principally for the transport. Other forms of flat engines include two stroke A two-stroke engine is an internal combustion engine which completes the thermodynamic cycle in two movements of the piston . This increased efficiency is accomplished by using the beginning of the compression stroke and the end of the combustion stroke to perform simultaneously the intake and exhaust (or scavenging) functions. In this way two- diesel employing two crankshafts and pairs of opposing pistons Some variations of the Opposed Piston or OP designs use a single crankshaft like the Doxford ship engines and the Commer OP truck engines. They should not be confused with flat engines. Though flat engines are sometimes referred to as horizontally opposed, they are very different mechanically.
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Configuration
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Flat engines have a lower center of gravity The center of mass of a system of particles is a specific point at which, for many purposes, the system's mass behaves as if it were concentrated. The center of mass is a function only of the positions and masses of the particles that comprise the system. In the case of a rigid body, the position of its center of mass is fixed in relation to the than any other common configuration, so vehicles using them should benefit from better stability and control. They are, however, also wider than more traditional configurations and the extra width causes problems fitting the engine into the engine bay of a front-engined car. Some well-known forms of flat engines tend to restrict lean and cornering in motorcycles. Flat engines lend themselves well to aircraft engines An aircraft engine is a propulsion system for an aircraft. Aircraft engines are almost always either lightweight piston engines or gas turbines. This article is an overview of the basic types of aircraft engines and the design concepts employed in engine development for aircraft, where any extra building expense is of minor importance.
The flat configuration lends itself very well to air cooling Air cooling is a method of dissipating heat. It works by making the object to be cooled have a larger surface area or have an increased flow of air over its surface, or both. An example of the former is to add fins to the surface of the object, either by making them integral or by attaching them tightly to the object's surface . In the case of the designs such as the flat-4 A flat-4 or horizontally-opposed-4 is a flat engine with four cylinders arranged horizontally in two banks of two cylinders on each side of a central crankcase. The pistons are usually mounted on the crankshaft such that opposing pistons move back and forth in opposite directions at the same time, somewhat like a boxing competitor punching his in the VW Beetle The Volkswagen Type 1 is an economy car produced by the German auto maker Volkswagen from 1938 until 2003. The car was originally known as Käfer, the German word for "beetle," from which the popular English nickname originates. It was not until August 1967 that the Volkswagen corporation itself began using the name Beetle in marketing, Porsche 356 The Porsche 356 was the company's first production automobile. It was a lightweight and nimble handling rear-engine rear-wheel-drive 2 door sports car available in hardtop and convertible configurations. Design innovations continued during the years of manufacture, contributing to its motorsports success and popularity. Production started in 1948 and 912 The Porsche 912 was a sports car manufactured by Porsche of Germany between 1965 and 1969 as their entry-level model. The 912 was a nimble-handling compact performance four-seat vehicle, delivering 90 SAE horsepower at 5800 rpm. The 912 was also capable of up to 30 miles per US gallon fuel economy. This combination was possible because of a high-. The Chevrolet Corvair The Chevrolet Corvair is an automobile produced by the Chevrolet division of General Motors from 1959 to 1969, for the 1960–1969 model years. The Corvair was offered in a wide range of body styles, including four-door sedans, two-door coupes, convertibles, and station wagons. It was also built as a compact van similar to the Volkswagen bus, with used an air-cooled flat-6 The Chevrolet Corvair engine was a flat-6 piston engine used exclusively in the 1960s Chevrolet Corvair automobile. It was a highly unusual engine for General Motors: It was air-cooled, used a flat design, with aluminum heads (incorporating integral intake manifolds) and crankcase, with individual iron cylinder barrels. The heads were modeled, though this is something of a rarity in American designs. Both the older and newer models of the Porsche 911 The Porsche 911 is a sports car made by Porsche AG of Stuttgart, Germany. The famous, distinctive, and durable design is notable for being rear engined like the Porsche-designed Volkswagen Beetle it had been based on. The car was also air-cooled until the introduction of the all-new Type 996 in 1998. Since its introduction in autumn 1963, it has use a flat-6 A flat-6 or horizontally-opposed-6 is a flat engine with six cylinders arranged horizontally in two banks of three cylinders on each side of a central crankcase. The pistons are mounted to the crankshaft such that opposing pistons move back and forth in opposite directions at the same time, somewhat like a boxing competitor punching their gloves, at first air cooled but later models are water-cooled. These automobiles situate the engine in the rear rather than the front, where its width does not interfere with the steering of the front wheels.
Front-mounted air-cooled flat-twin A flat-twin is a two cylinder internal combustion engine with the cylinders arranged on opposite sides of the crankshaft. It is part of the class of flat engines, sub-type "boxer", and shares most characteristics of those engines engines were used by Citroën Citroën is a French automobile manufacturer. Founded in 1919 by André Citroën, it was the world's first mass-production car company outside of the USA. Since 1976 it has been part of PSA Peugeot Citroën, and its headquarters is on rue Fructidor, Paris in their model 2CV The Citroën 2CV was an economy car produced by the French automaker Citroën from 1949 to 1990. It was technologically advanced and innovative, but with extremely utilitarian and deceptively simple Bauhaus inspired bodywork, that belied the sheer quality of its underlying engineering. It was designed to move the French peasantry on from horses and its derivatives, while the GS The Citroën GS and Citroën GSA (1980–86) were small family cars produced by the French automaker Citroën. The GS was voted European Car of the Year for 1971, and was probably the most technologically advanced car in its class when launched, with class leading comfort, safety and aerodynamics.[citation needed], GSA The Citroën GS and Citroën GSA (1980–86) were small family cars produced by the French automaker Citroën. The GS was voted European Car of the Year for 1971, and was probably the most technologically advanced car in its class when launched, with class leading comfort, safety and aerodynamics.[citation needed], Oltcit The Oltcit was a Romanian car developed in co-operation with Citroën of France in the 1980s. It is a small three-door hatchback, based on the Citroën Prototype Y and built in Craiova at the Automobile Craiova plant used a flat-4, and a flat-6 was proposed for the DS The Citroën DS is an executive car produced by the French manufacturer Citroën between 1955 and 1975. Styled by Italian sculptor and industrial designer Flaminio Bertoni, the DS is known for its futuristic body design and innovative technology, including hydropneumatic self-leveling suspension, but rejected. BMW Bayerische Motoren Werke AG (BMW), (English: Bavarian Motor Works) is a German automobile, motorcycle and engine manufacturing company. Founded in 1916, it is known for its performance and luxury vehicles. It owns and produces the MINI brand, and is the parent company of Rolls-Royce Motor Cars used an air-cooled flat-twin in almost all of its motorcycles A motorcycle is a single-track, two-wheeled motor vehicle. Motorcycles vary considerably depending on the task for which they are designed, such as long distance travel, navigating congested urban traffic, cruising, sport and racing, or off-road conditions. Being the most affordable form of motorised transport, in some parts of the world they are from 1921 until 1980, and still depends heavily on this layout, using it in many models including the most popular.
All versions of the Subaru Impreza "Impreza" is a coined word, deriving from an originally Italian word, impresa, meaning a feat or achievement. In Polish, "Impreza" means "party", "event" or "show", Forester The Subaru Forester, is a tall, all-wheel drive Compact Sports Utility Vehicle manufactured since 1997 by Subaru — currently in its third generation and now marketed as a compact crossover. Originally introduced to the United States in 1998, the Forester shared its platform with the Impreza up to the third generation and now features a hybrid, Tribeca The Subaru Tribeca is a mid-size crossover SUV sold by Japanese automaker Subaru. The Tribeca was first sold as a 2006 model, with five-seat and seven-seat trims. Built on the Subaru Legacy platform, the Tribeca was inspired by the B9X concept car and has now evolved into its second styling generation, Legacy The Legacy is a mid-size car introduced by the Japanese manufacturer Subaru in February 1989 as a larger companion to the company's Leone/Loyale. Worldwide distribution started in 1990. In Australia, the Legacy bears the name Liberty out of respect for Legacy Australia, an organization which aids veterans and their families during and after wars and SVX use either a flat-4 or flat-6 engine.
"Boxers" can be subdivided, since true boxers have each crankpin controlling only one piston/cylinder, and 180° engines A flat engine is an internal combustion engine with multiple pistons that all move in the horizontal plane. The most popular and significant layout has cylinders arranged in two banks on either side of a single crankshaft, generally known as "boxers". There is a widely-used but technologically less significant form consisting of a share crankpins.
- The boxer engine (the true horizontally opposed engine) has corresponding pistons reaching top dead center In a reciprocating engine, the dead center is the position of a piston in which it is farthest from, or nearest to, the crankshaft. The former is known as top dead center while the latter is known as bottom dead center (BDC) (TDC) simultaneously.
- The 180° V engine A V engine is a common configuration for an internal combustion engine. The cylinders and pistons are aligned, in two separate planes, so that they appear to be in a "V" when viewed along the axis of the crankshaft. The V configuration generally reduces the overall engine length, height and weight compared to an equivalent inline has corresponding pistons sharing a crank pin In a reciprocating engine, the crankpins, also known as crank journals are the bearing journals of the big end bearings, at the ends of the connecting rods opposite to the pistons on the crankshaft and reaching top dead center half a crankshaft revolution apart. They may use regular connecting rods In a reciprocating piston engine, the connecting rod or conrod connects the piston to the crank or crankshaft side by side, or use a master/slave system, or a fork-and-blade system. Flat engines with more than eight cylinders are most commonly V engines.
Boxer engines must not be confused with opposed piston engines Some variations of the Opposed Piston or OP designs use a single crankshaft like the Doxford ship engines and the Commer OP truck engines. They should not be confused with flat engines. Though flat engines are sometimes referred to as horizontally opposed, they are very different mechanically, which are based on a quite different concept using two crankshafts. These can be used in vehicles such as tanks.
Boxer engines
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Boxer engines got their name because each pair of pistons moves simultaneously in and out rather than alternately, like boxers showing they're ready by clashing their gloved fists against each other before a fight. Boxer engines of up to eight cylinders have proved highly successful in automobiles An automobile or motor car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor. Most definitions of the term specify that automobiles are designed to run primarily on roads, to have seating for one to eight people, to typically have four wheels, and to be constructed principally for the transport and up to six cylinders in motorcycles, and continue to be popular for light aircraft Examples of light aircraft include the entire range of Cessna propeller driven aircraft from the Cessna 120 up to and including the Cessna Caravan; Piper, Beechcraft and Cirrus aircraft; GA8 Airvan; Aviat Husky and the Robin DR400 engines.
Boxers are one of only three cylinder layouts that have a natural dynamic balance; the others being the straight-6 The straight-six engine or inline-six engine is a six cylinder internal combustion engine with all six cylinders mounted in a straight line along the crankcase. The single bank of cylinders may be oriented in either a vertical or an inclined plane with all the pistons driving a common crankshaft. Where it is inclined, it is sometimes called a and the V12 Since each cylinder bank is essentially a straight-6, this configuration has perfect primary and secondary balance no matter which V angle is used and therefore needs no balance shafts. A V12 with two banks of six cylinders angled at 60°, 120°, or 180° from each other has even firing with power pulses delivered twice as often per revolution as,. These engines can run very smoothly and free of unbalanced forces with a four-stroke cycle Today, internal combustion engines in cars, trucks, motorcycles, aircraft, construction machinery and many others, most commonly use a four-stroke cycle. The four strokes refer to intake, compression, combustion , and exhaust strokes that occur during two crankshaft rotations per working cycle of the Gasoline engine and Diesel engine and do not require a balance shaft In piston engine engineering, a balance shaft is an eccentric weighted shaft which offsets vibrations in engine designs that are not inherently balanced . They were first invented by British engineer Frederick Lanchester in 1904 or counterweights on the crankshaft The crankshaft, sometimes casually abbreviated to crank, is the part of an engine which translates reciprocating linear piston motion into rotation. To convert the reciprocating motion into rotation, the crankshaft has "crank throws" or "crankpins", additional bearing surfaces whose axis is offset from that of the crank, to to balance the weight of the reciprocating parts, which are required in other engine configurations. Note that this is generally true of boxer engines regardless of the number of cylinders (assumed to be even), but not true for all V or inline engines. However, in the case of boxer engines with fewer than six cylinders, unbalanced moments (a reciprocating torque also known as a "rocking couple") are unavoidable when the output is a crankshaft due to the "opposite" cylinders being not exactly opposite but offset slightly.
Boxer engines (and flat engines in general) tend to be noisier than other common engines for both intrinsic and other reasons, eg in cars, valve clatter from under the bonnet is not damped by large air-filters and other components. Boxers use a lighter crankshaft without need of balance weights, so should be able to accelerate faster - but in practice (eg in cars) they would suffer excessive torsional vibrations at low speeds so are fitted with a larger flywheel that negates the advantage. They have a characteristic smoothness throughout the rev range and, when combined with a mounting position immediately ahead of the rear axle, offer a low center of gravity and largely neutral handling.
180° V-engines
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Non-boxer flat engines have been used in performance and racing cars, notably 180 degree V12s. Ferrari used a 180° version of the Colombo V12 in the Testarossa and Berlinetta Boxer models. The Porsche 917 flat 12 engine is also not a boxer.
This configuration is sometimes termed a 180° V engine because like most other V engine layouts each pair of pistons share a crank pin (also referred to as a crankshaft throw). In a 180° V engine when one piston of a pair is at Top Dead Centre the other will be at BDC. In a boxer engine a pair of pistons will be on crank pins 180° apart so that both pistons in a pair will be at TDC at the same time.
Notable flat engines
Subaru Boxer Turbodiesel engine cutaway display- In 1896, Karl Benz invented the first internal combustion engine with horizontally opposed pistons
- In 1923 Max Friz designed the first BMW motorcycles, choosing a 500 cc boxer engine and unit transmission with shaft drive. This engine type is still in production today. The BMW 247 engine, known as an airhead due to its air cooling, was produced until 1995. BMW replaced it with the oilhead engine with partial oil cooling and four valves per cylinder, but still retaining the same boxer twin configuration.
- In 1948 Preston Tucker modified a helicopter flat-6 to be rear mounted in his Tucker Torpedo
- The Volkswagen air-cooled flat-4 engine used in the Volkswagen Beetle, SP2 and Karmann Ghia, and later developed further for the Volkswagen Type 2 (Bus) transporters and Volkswagen Type 3 cars
- The Citroën 2CV and Panhard air-cooled flat-2 engines, both influenced by the flat-2s of BMW
- The air-cooled Chevrolet Corvair OHV flat-6
- In 1960 Lancia's flat-4 water-cooled engine debuted for the Lancia Flavia model, first Italian front-wheel drive car, like 1500 cc 90 bhp (67 kW) din coupè version and during the years become a 2000 cc with 142 bhp (106 kW) when was mounted the first electronic Injection by Bosch in 1970 in a flat four engine, Lancia also rebuild a new big flat-4 engine in 1976, 2484 cc, for his upper size model Lancia Gamma, this engine was also tested by Squadra Corse Lancia in 1978 with 16 valves and Turbo supercharged, over 300 bhp (220 kW), for the racing Car Lancia Beta Montecarlo prototype (car after becomes World Champion of Makes in 1979 with a different engine). Last Flat-4 engine by Lancia was produced in 1984 on final production of Lancia Gamma, replaced by new Lancia Thema
- The flat-4 engines in Alfa Romeo's Alfasud, Sprint, 33 and early versions of the 145. The last of the line was a 1712 cc flat-4, 16 valves, producing up to 137 bhp (102 kW).
- The water-cooled front-mounted flat-4 and flat-6 engines used by Subaru in all of its mid-sized cars; Subaru refers to these as boxer engines in publicity commentary, and include a variety of naturally aspirated and turbo driven engines; in their turbo engines from 1983 to current, both closed and semi-closed short blocks have been used. Subaru also offers a boxer turbodiesel,[1] the world's first to be fitted into a passenger car.
- Since its introduction in 1975, the Honda Goldwing has utilized a boxer engine, a 4-cylinder until 1987, and 6-cylinders since. The water-cooled SOHC 1832 cc flat-6 is fitted to the Honda Goldwing from 2001 on.
- The air-cooled flat-4, flat-6 and flat-8 engines were used for many years in early Porsches. The flat-12 in the 917 model is a 180° V-engine and not a boxer.
- The water-cooled flat-6 engines in the Porsche Boxster, Cayman and later 911 models
- General aviation aircraft often use air-cooled flat-4 and flat-6 engines made by companies such as Lycoming, Continental. Ultralight and microlight aircraft often use engines such as the Rotax 912 or Jabiru 2200.
Flat engine designs
Other engine designs
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See also
References
- ^ "Greencarcongress". Legacy Diesel Announcement. http://www.greencarcongress.com/2008/01/subarus-first-b.html. Retrieved on 2008-01-23.
External links
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Categories: Piston engine configurations | Boxer engines
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gomez
Wed, 17 Jun 2009 18:50:28 GM
Not bad! Here's the story from MotorAuthority The eleventh International . Engine. of the Year Awards winners have just been announced and this year it.
