The scroll-type supercharger is a scroll compressor used as a positive displacement orbiting-spiral supercharger. It is a compromise between the more rugged rotating lobe, and the more efficient sliding vane type superchargers, and is considered to offer the highest potential in regard to efficiency, noise and pressure fluctuation. [1]
The basic concept of the scroll-type supercharger was invented by Léon Creux of France in 1905, [2] originally for aircraft use, though Creux did consider it as a possible form of steam engine. However, Creux's supercharger failed due to the relatively poor casting techniques available at the time. This type of supercharger has not seen widespread use in the aviation role, but has been used on a small number of automotive applications.
The moving parts of the supercharger is a disc-shaped displacer with identical spirals (or scrolls) projecting from each side, and manufactured from light alloy to reduce inertia. A pair of fixed scrolls supported by the end walls of the compressor chamber are interleaved with the moving scrolls. Rather than rotating, the displacer is driven in an orbital motion to create a pumping action between the pairs of scrolls.
Air is pulled into the device when the moving scrolls are at their furthest from the fixed scrolls, leaving a large gap. As the shaft rotates the gap closes, and the point of widest opening rotates to a point further "into" the charger. As the process continues the gap eventually ends up on the middle of the housing, at the point where the higher pressure air exhausts into the engine. The scrolls are shaped so the gap slowly decreases in size as it moves to the centre, thereby compressing the air.
The edges of the scrolls are sealed by strip-type seals, while the supercharger's main shaft bearings use radial seals to prevent the charge air from becoming contaminated with oil. [3]
The most common and well known scroll-type supercharger is the G-Lader (Lader is German for charger), designed by Volkswagen for use in a version of the Mk2 Polo called the GT G40. Launched first as a limited batch of about 500 cars in 1987, most were sold to Volkswagen workers.[ citation needed ] A normal production version of the G40 was launched as part of the Mk2F range. The name comes from the "G" shape of its compression channels. It was mounted on a 1,272 cc (77.6 cu in ) petrol engine, which offered performance about that of a 2 L (122 cu in) naturally aspirated engine.
A similar, but larger G60 became available in the Volkswagen Corrado during the early 1990s, and was also available in limited numbers in the Volkswagen Passat and Volkswagen Golf. The G60 won International Engine of the Year [ citation needed ] when it was introduced in 1989.
The "40" and "60" denote the displacer scroll width in millimetres.
All supercharger types benefit from the use of an intercooler to get rid of the heat produced during compression, and therefore help increase the density of the charged air.
In an internal combustion engine, a turbocharger is a forced induction device that is powered by the flow of exhaust gases. It uses this energy to compress the intake air, forcing more air into the engine in order to produce more power for a given displacement.
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A centrifugal supercharger is a specialized type of supercharger that makes use of centrifugal force in order to increase the manifold air pressure, MAP. An increased MAP allows the engine to burn more fuel, which results in an increased power output. Centrifugal superchargers are generally attached to the front of the engine via a belt-drive or gear-drive from the engine's crankshaft.
A compressor is a mechanical device that increases the pressure of a gas by reducing its volume. An air compressor is a specific type of gas compressor.
The Volkswagen Corrado is a compact four passenger (2+2), three door, front-engine, front-wheel-drive liftback coupe marketed by Volkswagen from 1988 until 1995, and manufactured by Karmann in Osnabrück, Germany.
A drive shaft, driveshaft, driving shaft, tailshaft, propeller shaft, or Cardan shaft is a component for transmitting mechanical power, torque, and rotation, usually used to connect other components of a drivetrain that cannot be connected directly because of distance or the need to allow for relative movement between them.
A scroll compressor is a device for compressing air or refrigerant. It is used in air conditioning equipment, as an automobile supercharger and as a vacuum pump. Many residential central heat pump and air conditioning systems and a few automotive air conditioning systems employ a scroll compressor instead of the more traditional rotary, reciprocating, and wobble-plate compressors.
A twincharger refers to a compound forced induction system used on some internal combustion engines. It is a combination of an exhaust-driven turbocharger and a mechanically driven supercharger, each mitigating the weaknesses of the other.
The Volkswagen G60 and G40 were inline–four-cylinder automobile petrol engines, which used a specific method of forced induction by way of a scroll-type supercharger. The G60 engine was formerly manufactured by the German automaker Volkswagen Group and was installed in a limited number of their 'hot hatch' cars from their Volkswagen Passenger Cars marque from August 1988 to July 1993.
A swing-piston engine is a type of internal combustion engine in which the pistons move in a circular motion inside a ring-shaped "cylinder", moving closer and further from each other to provide compression and expansion. Generally two sets of pistons are used, geared to move in a fixed relationship as they rotate around the cylinder. In some versions the pistons oscillate around a fixed center, as opposed to rotating around the entire engine. The design has also been referred to as a oscillating piston engine, vibratory engine when the pistons oscillate instead of rotate, or toroidal engine based on the shape of the "cylinder".
A rotary vane pump is a type of positive-displacement pump that consists of vanes mounted to a rotor that rotates inside a cavity. In some cases these vanes can have variable length and/or be tensioned to maintain contact with the walls as the pump rotates.
A rotary-screw compressor is a type of gas compressor, such as an air compressor, that uses a rotary-type positive-displacement mechanism. These compressors are common in industrial applications and replace more traditional piston compressors where larger volumes of compressed gas are needed, e.g. for large refrigeration cycles such as chillers, or for compressed air systems to operate air-driven tools such as jackhammers and impact wrenches. For smaller rotor sizes the inherent leakage in the rotors becomes much more significant, leading to this type of mechanism being less suitable for smaller compressors than piston compressors.
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The Volkswagen Polo Mk2 is the second generation of the Volkswagen Polo supermini. It was produced from late 1981 until 1994. It received a major facelift in 1990 and was available in three different body styles, including a distinctive kammback-styled hatchback, nicknamed "breadvan" in the UK but referred to as a Steilheck in Germany. The sedan version typically received the name of Volkswagen Derby.
In an internal combustion engine, a supercharger compresses the intake gas, forcing more air into the engine in order to produce more power for a given displacement.
The Volkswagen Polo Mk2 and Polo Mk2F were available as supercharged G40 models - called the Volkswagen Polo G40.
The G-Lader is a scroll-type supercharger used in various Volkswagen Passenger Cars models. Its purpose is to increase the motive power output from the internal combustion engine attainable with a given engine displacement. Since it is not enough to simply inject more fuel, as this produces too rich an air-fuel mixture, more intake air has to be added at the same time. This can be achieved with an exhaust-driven turbocharger, or a crankshaft-driven positive displacement compressor. The G-Lader is in the compressor category, since it is crankshaft-driven and does not have the "lag" usually associated with turbocharged engines.
An electric supercharger is a specific type of supercharger for internal combustion engines that uses an electrically powered forced-air system that contains an electric motor to pressurize the intake air. By pressurizing the air available to the engine intake system, the air becomes more dense, and is matched with more fuel, producing the increased horsepower to the wheels.
An internal combustion engine is a heat engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combustion engine, the expansion of the high-temperature and high-pressure gases produced by combustion applies direct force to some component of the engine. The force is typically applied to pistons, turbine blades, a rotor, or a nozzle. This force moves the component over a distance, transforming chemical energy into kinetic energy which is used to propel, move or power whatever the engine is attached to.