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Variator
A variator is a device that can change its parameters, or can change parameters of other devices. Often a variator is a mechanical power transmission device that can change its gear ratio continuously (rather than in steps). Examples * Beier variable-ratio gear * Continuously variable transmission * Evans friction cone * NuVinci Continuously Variable Transmission * Variator (variable valve timing) * Variomatic * VANOS See also * Epicyclic gearing An epicyclic gear train (also known as a planetary gearset) consists of two gears mounted so that the center of one gear revolves around the center of the other. A carrier connects the centers of the two gears and rotates the planet and sun gea ... Mechanical power control {{Mech-engineering-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Variator (variable Valve Timing)
Variable valve timing (VVT) is a system for varying the valve opening of an internal combustion engine. This allows the engine to deliver high power, but also to work tractably and efficiently at low power. There are many systems for VVT, which involve changing either the relative timing, duration or opening of the engine's inlet and exhaust valves. One of the first practical VVT systems used a variator to change the phasePhase refers to the relative timing between the inlet and exhaust camshafts, expressed as an angular measure. of the camshaft and valves. This simple system cannot change the duration of the valve opening, or their lift.'Lift' is the distance by which the valves open. Later VVT systems, such as the helical camshaft or the movable fulcrum systems, could change these factors too. Despite this limitation, the variator is a relatively simple device to add to an existing engine and so they remain in service today. As the benefit of the variator relies on changing the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NuVinci Continuously Variable Transmission
Internal CVP shift mechanism Tilting ball variator schematic. The rotating input disk drives rotation of the balls, which drive the rotating output disk. The rotation axis of the balls can be changed in order to change the ratio of input to output speed The NuVinci Continuously Variable Planetary Transmission is a type of roller-based continuously variable transmission (CVT) manufactured and marketed by the American company Fallbrook Technologies Inc. The design saw its initial market application as a bicycle gearing system, first available in December 2006 in the Netherlands and United States. NuVinci CVP technology is also currently under development for other applications, including wind turbines, light electric vehicles, outdoor power equipment, and automotive front-end accessory drives. History Mechanical variators have existed since the 1800s, and they have been used successfully in machinery, particularly the Kopp tilting ball variator. Various attempts have been mad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beier Variable-ratio Gear
The Beier variable-ratio gear or Beier variator is a mechanical drive offering a continuously variable gear ratio between input and output. The gear relies on the inter-meshing of a number of thin disks. By varying their separation, the effective radius of one disk varies, thus changing the overall gear ratio. This varying-radius principle is shared by a number of other variator mechanisms. An advantage of the Beier is that a large number of disks may be stacked on a common shaft, thus increasing its torque capacity for only a small increase in overall length. The mechanism consists of a spring-loaded stack of thin disks on a central shaft. Around this are arranged other stacked disk packs on a number of planetary shafts, usually three. These shafts are mounted on swinging arms, so that they may be moved in and out together. The central disks are thin, with a thickened rim. The planet disks are tapered across their radius, at an included angle of around 3°. When the disks are i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Continuously Variable Transmission
A continuously variable transmission (CVT) is an automatic transmission that can change seamlessly through a continuous range of gear ratios. This contrasts with other transmissions that provide a limited number of gear ratios in fixed steps. The flexibility of a CVT with suitable control may allow the engine to operate at a constant RPM while the vehicle moves at varying speeds. CVTs are used in cars, tractors, side-by-sides, motor scooters, snowmobiles, bicycles, and earthmoving equipment. The most common type of CVT uses two pulleys connected by a belt or chain; however, several other designs have also been used at times. Types Pulley-based The most common type of CVT uses a V-belt which runs between two variable-diameter pulleys. The pulleys consist of two cone-shaped halves that move together and apart. The V-belt runs between these two-halves, so the effective diameter of the pulley is dependent on the distance between the two-halves of the pulley. The V-shape ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Power Transmission
Power transmission is the movement of energy from its place of generation to a location where it is applied to perform useful work. Power is defined formally as units of energy per unit time. In SI units: :\text = \frac = \frac Since the development of technology, transmission and storage systems have been of immense interest to technologists and technology users. Electrical power With the widespread establishment of electrical grids, power transmission is usually associated most with electric power transmission. Alternating current is normally preferred as its voltage may be easily stepped up by a transformer in order to minimize resistive loss in the conductors used to transmit power over great distances; another set of transformers is required to step it back down to safer or more usable voltage levels at destination. Power transmission is usually performed with overhead lines as this is the most economical way to do so. Underground transmission by high-voltage c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gear Ratio
A gear train is a mechanical system formed by mounting gears on a frame so the teeth of the gears engage. Gear teeth are designed to ensure the pitch circles of engaging gears roll on each other without slipping, providing a smooth transmission of rotation from one gear to the next. Features of gears and gear trains include: * The gear ratio of the pitch circles of mating gears defines the speed ratio and the mechanical advantage of the gear set. * A planetary gear train provides high gear reduction in a compact package. * It is possible to design gear teeth for gears that are non-circular, yet still transmit torque smoothly. * The speed ratios of chain and belt drives are computed in the same way as gear ratios. See bicycle gearing. The transmission of rotation between contacting toothed wheels can be traced back to the Antikythera mechanism of Greece and the south-pointing chariot of China. Illustrations by the Renaissance scientist Georgius Agricola show gear trains with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Variomatic
Variomatic is the continuously variable transmission (CVT) of the Dutch car manufacturer DAF, originally developed by Hub van Doorne. It is a stepless, fully-automatic transmission, consisting of a V-shaped drive-belt, and two pulleys, each of two cones, whose effective diameter can be changed so that the "V" belt runs nearer the spindle or nearer the rim, depending on the separation of the cones. These are synchronized so that the belt always remains at the same optimal tension. History The Variomatic was the first commercially successful CVT (as opposed to shifting between separate gears). In theory, this always produces the optimum torque. The Variomatic was introduced by DAF in 1958, also putting an automatic gearbox in the Netherlands for the first time. The ''Variomatic'' was introduced on the DAF 600. Efficiency Because most of the time the engine runs at its most economical speed, the fuel consumption of this car was acceptable, although the fuel efficiency of any mec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
VANOS
VANOS is a variable valve timing system used by BMW on various automotive petrol engines since 1992. The name is an abbreviation of the German words for ''variable camshaft timing'' (german: variable Nockenwellensteuerung). The initial version (retrospectively renamed "single VANOS") was solely used on the intake camshaft, while the later "double VANOS" systems are used on intake and exhaust camshafts. Since 2001, VANOS is often used in conjunction with the valvetronic variable valve lift system. Operation VANOS is a variator system that varies the timing of the valves by moving the position of the camshafts in relation to the drive gear. The relative timing between inlet and exhaust valves is changed. At lower engine speeds, the position of the camshaft is moved so the valves are opened later, as this improves idling quality and smooth power development. As the engine speed increases, the valves are opened earlier: this enhances torque, reduces fuel consumption and lowers emi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epicyclic Gearing
An epicyclic gear train (also known as a planetary gearset) consists of two gears mounted so that the center of one gear revolves around the center of the other. A carrier connects the centers of the two gears and rotates the planet and sun gears mesh so that their pitch circles roll without slip. A point on the pitch circle of the planet gear traces an epicycloid curve. In this simplified case, the sun gear is fixed and the planetary gear(s) roll around the sun gear. An epicyclic gear train can be assembled so the planet gear rolls on the inside of the pitch circle of a fixed, outer gear ring, or ring gear, sometimes called an ''annular gear''. In this case, the curve traced by a point on the pitch circle of the planet is a hypocycloid. The combination of epicycle gear trains with a planet engaging both a sun gear and a ring gear is called a ''planetary gear train''.J. J. Uicker, G. R. Pennock and J. E. Shigley, 2003, ''Theory of Machines and Mechanisms,'' Oxford University Pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
