A continuous variable transmission ( CVT ), also known as single speed transmission , nonstop transmission , pulley transmission, or, in the case of a motorbike, twist-and-go, is an automatic transmission that can change seamlessly through various effective gear ratios. This contrasts with other mechanical transmissions that offer a fixed gear ratio. The flexibility of the CVT with the appropriate control allows the input shaft to maintain a constant angular velocity even when the output velocity varies.
Belt-driven designs offer an efficiency of about 88%, which, while lower than a manual transmission, can be offset by lower manufacturing costs and by allowing the engine to run at the most efficient speed for various output speeds. When power is more important than the economy, CVT ratios can be changed to allow the engine to spin at RPM where it generates the greatest power. This is usually higher than the RPM that achieves peak efficiency. In low-mass low-torque applications (such as motor scooters), the belt-driven CVT also offers ease of use and mechanical simplicity.
CVT does not strictly require the presence of clutch. Nevertheless, in some vehicles (eg motorcycles), centrifugal couplings are added to facilitate a "neutral" attitude, which is useful when stationary or manually backs into the parking lot.
Video Continuously variable transmission
Usage
Simple rubber belt (non-stretchy circles manufactured using a variety of highly durable and flexible materials) CVT is typically used on small motor vehicles, where mechanical simplicity and ease of use exceeds its comparative inefficiency. Almost all snowmobiles, utility vehicles, golf carts and motor scooters use CVT, usually rubber belts or variable pulley variations. Many small tractors and self-made cutters for homes and gardens also use a simple rubber belt CVT. Hydrostatic systems are more common in larger units - self-propelled cutting machines running from a variety of belt slips.
Hydrostatic CVT is commonly used in agricultural equipment and small to medium sized earth moving. Since machines in these machines are typically run on constant power settings to provide hydraulic power or for electric engines, the losses in mechanical efficiency are offset by increased operational efficiency, such as reduced back and forth backlift times in ground transfer operations. The transmission output varies to control the speed and direction of travel. This is particularly useful in equipment designed for spinning or skid steering through differential power applications because the required differential steering action can be easily supplied by an independent CVT, allowing the steering to be achieved without braking losses or losing traction effort and allowing the engine to spin in place. In logging or harvest operations, the CVT allows forward speed of the tractor or a combined harvester adjusted separately from the engine speed. This allows the operator to slow down or accelerate as needed to accommodate variations in plant thickness.
CVT has been used in aircraft power systems since the 1950s and in the Sports Car Club of America (SCCA) Formula 500 racing cars since the early 1970s. Agricultural equipment, ie harvester combines, using variable belt belts in the early 1950s, as well. The CVT was banned from Formula 1 in 1994 because of concerns that the best funded team would dominate if they managed to make a decent F1 CVT. Recently, the CVT system has been developed for go karts and has been shown to improve engine performance and life expectancy. Tomcar range of off-road vehicles also use CVT system.
Some drilling machines and milling machines contain a pulley-based CVT in which the output shaft has a pair of adjustable manual conical pulle sections in which the wide drive belt of the motor loop. Pulleys on motors, however, usually remain in diameter, or may have a series of specific diameter steps to allow selection of the speed range. The handwheel on the drill press, marked with the scale corresponding to the desired engine speed, is fitted to the reduction gearing system for the operator to precisely control the width of the gap between the pulley sections. The width of this gap thus adjusts the rotation ratio between the fixed motor pulley and the variable output shaft pulley, changing the chuck speed. The tensioner pulley is implemented in belt transmission to take or loosen slack on the belt as speed is changed. In many cases, the speed must be changed with the motor running.
CVT must be distinguished from power-sharing transmissions (PST), as used on newer hybrid cars, such as the Toyota Prius, Highlander and Camry, Nissan Altima, and the latest Ford Escape Hybrid models. The CVT technology uses only one input of the prime mover and provides variable speed and torque output, whereas PST technology uses two main driving inputs and varies its contribution ratio to the speed and output power. This transmission is fundamentally different.
Some vehicles that offer CVT are hybrid Chrysler Pacifica, Ford C-MAX hybrid, Mitsubishi Lancer, Dodge Caliber, Toyota Corolla, Scion iQ, Honda Insight, Fit, CR-Z hybrid, CR-V, Capa, Honda Civic, Honda Accord, Nissan Tiida/Versa (SL, SV, and Note S Plus or higher models), Cube, Juke, Sentra, Altima, Maxima, 2013 1.2 Notes, Rogue, X-Trail, Murano, Pathfinder, Sunny and Micra non-Mexico , Jeep Patriot and Compass, Suzuki SX4 S-Cross, and Subaru Forester, Impreza, Legacy, Outback and Crosstrek, Suzuki Kizashi, Toyota Allion 2009 and so on, Toyota Premio 2009 and beyond, Toyota Avalon, Toyota Mark X,
Maps Continuously variable transmission
Type
Pulleys of variable-diameter (VDP) or Reeves drive
In this most common CVT system, there are two separate V-belt pulleys with their rotation axes, with V-belts running between them. The gear ratio is changed by moving two sheaves from one pulley closer together and two sheaves from the other further farther apart. The belt-shaped V-shaped section causes it to rise higher on one pulley and lower on the other. This changes the effective diameter of both pulleys, which changes the overall gear ratio. Since the distance between the pulleys and the belt length does not change, the two pulleys must be adjusted (one larger, the other smaller) simultaneously to maintain the exact amount of voltage on the belt. A simple CVT that combines a centrifugal drive pulley with a spring-loaded pulley that often uses a belt voltage to affect the corresponding adjustment of the actuated pulle. The V-belt must be very rigid in the axial direction of the pulley to make only short radial motions while sliding in and out of the pulleys. The ubiquitous Chinese gy6-type type uses this type of CVT drive system.
Steel reinforced v-belts is sufficient for low-torque low-mass applications such as utility vehicles and snowmobiles but mass applications and higher torques such as automobiles require chains. Each chain element must have a conical side corresponding to the pulley when the belt runs on the outer radius. As the chain moves to the pulley, the contact plane becomes smaller. Since the contact plane is proportional to the number of elements, the chain belt requires many very small elements. The shape of an element is governed by a static column. The pulley-radial thickness of the belt is a compromise between maximum gear ratio and torque. For the same reason, the axis between the pulleys is as thin as possible. In CVT-based chains, lubricating films are applied to pulleys. It should be thick enough so that the pulley and chain are never touched and should be thin so as not to waste power when every element dives into the lubrication film. In addition, the chain elements stabilize about 12 steel bands. Each band is thin enough to easily bend. If bent, it has a perfect conical surface on its side. In band stacks each band corresponds to slightly different gear ratios, and thus they slide on top of each other and require oil between them. Also the outer bands glide through the stabilizer chain, while the center band can be used as a chain link.
Magnetic atau m
A continuous variable magnetic transmission system was developed at Sheffield University in 2006 and subsequently commercialized. m CVT is a variable magnetic transmission that provides an electrically controllable gear ratio. It can act as a power divider device and can match the fixed input speed of the prime mover to the variable load by importing/exporting electric power through the variator path. The m CVT is of particular interest as a highly efficient power-split device for a mix of parallel hybrid vehicles, but also has potential applications in renewable energy, marine propulsion and drive industry.
Transmission of unlimited variables (IVT)
A subset of CVT designs is called unlimited variable transmission (IVT or IVTs), where the range of the output shaft's speed ratio to include the shaft velocity includes the zero ratio that can be approached from the "higher" ratio specified. The zero output velocity (low gear) with limited input speed implies an infinite ratio of input-to-output velocity, which can continue to be approached from the infinite input value provided with IVT. Low gear is a reference to the low ratio of the output speed to the input speed. This low ratio is brought to an extreme by IVT, producing a neutral "tooth", or a non-driving "low" limit, where the output velocity is zero. Unlike neutral in normal automotive transmissions, IVT output rotation can be prevented because the reverse IVT operation may be unlimited, resulting in very high backdriving torque; in ratcheting IVT, however, the output can freely rotate toward the front.
In the early decades of the twentieth century, some small tractors and locomotives were built with disk-friction transmissions with output disks that rolled in front of the input disk. For discs of the same diameter, the effective gear ratio can be varied from 1: 1 when the contact point is on the perimeter of the input disk, to infinity when the point of contact is at the center, to -1: 1 when the point of contact is on the opposite end. Transmission on early Plymouth locomotives works in this way, while on tractors using friction disks, the reverse speed range is usually limited.
The ratcheting IVT dates back to before the 1930s; the original design turns the spinning motion into an oscillatory motion and returns to a rotating motion using a roller clutch. Medium adjustable oscillation stroke, varying the output speed of the shaft. The fundamental limitation is that when the transfer torque between the oscillatory paths separates the deflection changes causing high vibrations at higher torques. The original design is still produced today, and examples and animations from this IVT can be found here. Paul B. Pires creates more compact variations (radial symmetry) using a ratchet mechanism instead of a roller grip, so it does not have to rely on friction to drive output. Articles and sketches of these variations can be found here
Many IVTs are produced from a combination of CVTs with planetary gear systems that impose the rotation speed of the IVT output shaft equal to the difference between the two other velocities in IVT. This IVT configuration uses CVT as a continuous variable control (CVR) of the rotational speed of one of the three rotators of the planet gear system (PGS). If two speeds of the PGS rotator are the CVR input and output, there is a CVR setting which results in a zero IVT output speed. The maximum output/input ratio can be selected from unlimited practical possibilities through the selection of additional input or output gear, pulley or sprocket size without affecting zero output or overall system continuity. IVT is always involved, even during zero output adjustment.
IVT can in some implementations offer better efficiency in the preferred range of operations when compared to other CVTs because most of the power flows through planetary gear systems and not CVR controllers. Torque transmission capability can also be improved. Split strength splits are also possible for further improvements in efficiency, torque transmission capability and improved maintenance efficiency over a wide gear ratio range.
An example of the correct IVT is the Hydristor because the front unit connected to the engine can move from zero to 27 cubic inches (440 cm 3 ) per revolution forward and zero to -10 cubic inches (-160 cm < > 3 ) per revolution backwards. The rear unit is capable of zero to 75 cubic inches (1,230 cm 3 ) per revolution. However, whether this design enters production remains to be seen. Another example of true IVT being put into production recently and that continues under commercial development is from Torotrak.
Ratcheting
Ratcheting CVT is a transmission that relies on static friction and is based on a set of elements that are successively involved and then separated between the drive system and the driven system, often using oscillatory or indexing motions together with one-way or ratchet clutches that fix and summarize only movement "advanced". The transmission rate is adjusted by altering the linkage geometry in the oscillating element, so that the total added linkage rate is adjusted even when the average link speed remains constant. Power is transferred from input to output only when coupling or ratchet is activated, and therefore when it is locked into static friction mode where driving & amp; the rotating surface is pushed for a moment twisted together without a skid.
This CVT can transfer substantial torque, because the static friction actually increases relative to torque throughput, so slippage is not possible in well-designed systems. Efficiency is generally high, since most of the dynamic friction is caused by very few changes in the transition clutch speed. Weakness to the increased CVT is the vibration caused by the successive transitions in the speed required to accelerate the element, which must replace the previous power transmission element and slow down.
Ratcheting CVTs are distinguished from VDP and CVT-based rollers by being static friction-based devices, as opposed to dynamic friction-based devices that throw significant energy through slippage on a winding surface. An example CVT braking is a prototype as a protected bicycle transmission under AS. Patent 5,516,132 where a strong pedaling torque causes this mechanism to react to springs, moving the ring gears/wheel assemblies to a more concentric and lower gear position. When the paddling torque relaxes to a lower level, the transmission adjusts to the higher gear, accompanied by an increase in transmission vibration.
Hydrostatic
Hydrostatic transmission uses variable displacement pumps and hydraulic motors. All power is transmitted by hydraulic fluid. These types can generally transmit more torque, but can be sensitive to contamination. Some designs are also very expensive. However, they have the advantage that the hydraulic motor can be mounted directly to the wheel hub, allowing a more flexible suspension system and eliminating the efficiency losses from friction on the driving shaft and differential components. This type of transmission is relatively easy to use as all forward and backward speeds can be accessed using a single lever.
An integrated hydrostatic transaxle (IHT) uses one housing for the hydraulic element and a tooth reduction element. This type of transmission has been effectively applied to different versions of lawn mowers and cheap and expensive garden tractors.
One class of lawn mowers that has recently become more popular among consumers is a lawn mower with a zero radius. This lawn mower is traditionally supported with a wheel hub attached to a hydraulic motor driven by a continuous variable pump, but the design is relatively expensive.
Some heavy equipment can also be driven by hydrostatic transmission; eg agricultural machinery including collectors, joiners, and some tractors. Various heavy equipments that move the ground, such as compact and small wheel loaders, tracker type tractor and crawler, skid-steered loader and asphalt compactor use hydrostatic transmission. Hydrostatic CVT is usually not used for long-term high torque applications due to the heat generated by the flowing oil, although there are various oil cooling designs to help solve this problem.
Honda Motor DN-01 is the first consumer vehicle with hydrostatic drive that uses variable variable axial piston pump with variable-angle swashplate.
AGCO Corporation has used hydrostatic CVT transmission in agricultural equipment. Transmission divides the power between hydrostatic and mechanical transfers into the output shaft through the planet's gears in the forward direction of the journey. On the other hand the transfer of power is fully hydrostatic.
Naudic Addition (iCVT)
This is a chain-driven system advertised in * [1] Despite an iCVT work, it has the following drawbacks:
High friction loss
The variant valve of iCVT faltered using two small choking pulses. Here one choking pulley is positioned on the taut side of the iCVT chain. Therefore there is a considerable burden on the choke pulley, the amount of which is proportional to the voltage in the chain. Each clogged pulley is pulled by two chain segments, one chain link to the left and one on the right of the choking pulley; here if two segments of the chain are parallel to each other, then the load on the blocked pulley is twice the tension in the chain. But since both segments of the chain are likely not parallel to each other during the operation of iCVT, it is estimated that the load on the blocked pulley is between 1 and 1.8 times the chain voltage.
Also, the clogged pulley is so small that the timing arm is very small. The larger moment arm reduces the force required to rotate the pulley. For example, using a long lock, which has a large moment arm, to open the nut takes less power than using a short wrench, which has a small moment arm. Assuming that the diameter of the choke pulley is twice the diameter of the axis, which is a generous estimate, the friction resistance force in the outer diameter of the choke pulle is half the frictional resistance force on the choke pulley shaft.
Surprise and durability
The transmission rate of iCVT should be changed one increase in less than one full rotary of its variator pulley. This means that the diameter of the variator pulley transmission, made generally of rubber, shall be changed from a diameter having a circumferential length equal to the number of integers of teeth of another diameter having the same circumference length as the tooth integer; such as changing the diameter of a variator pulley transmission from a diameter having a circumferential length of 7 teeth to a diameter having a circumferential length of 8 gears for example. This is because if the transmission diameter diameter of the variator does not have the same circular length as the number of tooth integers, such as the length of the circumference 7Ã,½ of the tooth for example, improper involvement between the variator and chain pulley teeth will occur. For example, imagine having a bike pulley with 7Ã,½ teeth; here the improper involvement between the bike and chain pulleys will occur when the teeth behind the ½ gear space will be involved with the chain, as it is positioned a distance of ½ teeth late relative to the chain.
Regarding the preceding paragraph, the iCVT chain forms an open loop on its variator pulley which partially covers its variator pulley so that the open part, which is not covered by the chain, exists. This is similar to a bicycle sprocket where there is a part of the sprocket that is covered by a chain, and part of a sprocket not covered by the chain. During one full cycle, the toothed portion of the variator pulley of iCVT passes through the open part and moves back with the chain. Here if the transmission diameter diameter of the variator does not represent the number of integer teeth, improper re-involvement between the variator and chain pulley teeth will occur. Also, the diameter of the variator pulley transmission can not be changed when the toothed portion of the variator pulley covers the entire open part of the recurrence chain. Because this is similar to where the plate is glued in the open part of the chain loop, which does not allow the expansion or contraction of the chain loop as required for the variation diameter transmission pulse change. Therefore, the diameter of the variator pulley transmission shall be changed one increment during the interval in which the variator pulley rotates from the starting position where a portion of the variator pulley section is positioned on the open portion of the chain loop but does not encompass all the open parts, to the end position where the toothed variator pulley passes through the open part of the loop chain and will re-engage with the chain. Since it takes less than one full turn to rotate the variator pulley from its initial position to the end position mentioned in the previous sentence, the diameter of the variator pulley transmission must be changed one increment in less than one full cycle.
Additionally, as the transmission diameter increases, the chain must be pushed to the sloping surface of the pulley part of the variator pulley, while the voltage in the chain tends to pull the chain in the opposite direction. Therefore a large force, greater than the voltage in the chain, is required to change the transmission diameter. Since the transmission ratio must be changed in less than one full rotary of the variator pulley, the force must be applied to the pulley in a very short duration. If for example the variator pulley rotates at 3600 rpm, which is equivalent to 60 revolutions per second, then the force required to change the transmission ratio should be applied within 1/60 sec. It's like hitting something with a hammer. Therefore, here a significant shock load is applied to the variator pulley during the transmission ratio change which increases the transmission diameter. These shock charges can cause comfort problems for vehicle drivers using iCVT. Also iCVT should be designed to be able to withstand these shock loads that will most likely increase the cost and weight of an iCVT.
Capability and reliability of torque transfer
The pulley variator of the iCVT is formed by pins extending from one pulley to the other half of the pulley and sliding in the pulley groove of the pulley variator. Here the torque of the chain is transferred to the pin and then from the pin to the pulley section. Because the pins are round and curved, the contact line between the pins and the grooves is used to transfer the power from the pin to the groove. The number of forces that can be transmitted between two parts depends on the contact area of ​​two parts. Because the contact area between the pin and the groove is very small, the number of forces that can be transmitted between them, and therefore the torque capacity of iCVT, is limited.
Another possible problem with iCVT is that the variator pulley pins can fall out when they are not involved with their chain, and wearing pins and grooves from the pulley section can cause some serious performance and reliability issues.
Cone
CVT cones vary an effective gear ratio using one or more conical rolls. The simplest type of cone CVT, single-cone version, using wheels that move along the cone slope, creates variations between narrow and wide narrow diameter.
More sophisticated cone systems are also a type of cone CVT.
In a CVT with an oscillating cone, the torque is transmitted through friction from a number of conical variables (corresponding to the torque to be transmitted) to the center, barrel-shaped hub. The surface of the convex side of the hub with certain radius of curvature is smaller than the convex cone fingers. In this way, there will be only one (theoretical) contact point between each cone and hub at any time.
The new CVT using this technology, Warko, was presented in Berlin during the International Symposium CTI 6 Innovative Automotive Transmission, from December 3-7, 2007.
Warko's special characteristic is the absence of clutch: the engine is always connected to the wheel, and the rear drive is obtained by using the epicyclic system in the output. This system, named "power sharing", allows the machine to have "neutral teeth": when the engine spins (connected to the sun's teeth from the epicyclic system), the variator (ie planetary gear) will offset the rotation engine, resulting in the outer ring gear (which provide output) remain silent.
Radial roller
The working principle of this CVT is similar to a conventional oil pump, but, instead of pumping oil, a common steel roller is compressed.
The motion transmission between the rollers and the rotor is aided by tailored traction fluid, which ensures precise friction between surfaces and slows its use. Unlike other systems, the radial roller does not exhibit variations of tangential velocity (delta) along the contact lines on the rotor. From this, greater mechanical efficiency and working life are claimed.
Planetary
In the planet CVT, the gear ratio is shifted by tilting the axis of the ball continuously, to provide different contact radii, which in turn drive the disc input and output. The system can have multiple "planets" to transfer torque through several fluid patches. One commercial implementation is the NuVinci Continuous Variable Transmission.
History
Leonardo da Vinci, in 1490, drew on endlessly continuous transmission. Milton Reeves discovered a variable speed transmission for a saw mill in 1879, which he applied to his first car in 1896. The first patent for a friction-based CVT belt for a car was filed in Europe by Daimler and Benz in 1886, and US Patent for a toroidal CVT awarded in 1935.
In 1910, Zenith Motorcycles built a twin-engined V-motorcycle with Gradua-Gear, which is a CVT. In 1912, the British motorcycle manufacturer, Rudge-Whitworth, built Rudge Multigear. The Multi is a much better version of the Gradua-Gear Zenith.
Between 1913 and 1923 the Spanish manufacturer David produced the cyclecar with CVT.
The initial CVT app was in British Clyno car, introduced in 1923.
In 1926, George Constantinesco produced Constantinesco cars with a smooth, efficient, and inertia CVT mass, which he discovered in 1923, built into a two-cylinder engine.
During the late 1940s and early 1950s, Charles H. Miner of Denver, CO made significant developments in creating CVT by creating "Variable Speed ​​Clutch Pulley". He filed and awarded several US patents for his CVT system using a steel ball and centrifugal force to manipulate the moving side from the end of his V-belt coupling power. He formed a manufacturing company (Miner Pulley) in Denver and built a clutch coupe until he sold the company to Warner Clutch for health reasons. See US Patent US2974544 A for diagrams and details.
The CVT, called Variomatic, was designed and built by Hub van Doorne, co-founder of Van Doorne's Automobiel Fabriek (DAF), in the late 1950s, in particular to produce automatic transmissions for small, affordable cars. The first DAF van using the Van Doorne CVT, DAF 600, was produced in 1958. Van Doorne's patent was then transferred to a company called VDT (Van Doorne Transmissie BV) when the passenger car division was sold to Volvo in 1975 ; CVT was used in Volvo 340. In 1995, VDT was acquired by Robert Bosch GmbH.
For the 1965 model, Wheel Horse Products, Inc., of South Bend, Indiana, USA, introduced the first garden tractor equipped with a hydraulic CVT. Models 875 and 1075 include variable-displacement variable-displacement variable swlet-plate and fixed-displacement gear-type hydraulic motor assemblies incorporated into a single compact package, connected directly to a patented Wheel Horse Unidrive (TM) transaxle. Reverse is produced by reversing the pump flow through over-centering of the swash plate. Acceleration is limited and refined through the use of pressure accumulators and release valves located between the pump and the motor, to prevent sudden changes in possible speed with direct hydraulic clutch. The next version includes fixed swash plate motors, and ball pumps and sourced from Eaton and Sundstrand Corp.
Many snowmobiles use a CVT rubber belt. In 1974, Rokon offered a motorcycle with a CVT rubber belt.
CVT is used in multiple vehicles in all terrains. The first ATV equipped with the CVT was the Polaris Trail Boss in 1985.
In February 1987, Subaru released Justy in Tokyo with an electronically controlled continuous variable transmission (ECVT) developed by Fuji Heavy Industries that own Subaru, and Van Doorne Transmissie in the Netherlands. One and a half years later in November 1988, Subaru also issued Justy 4WD ECVT, Justy with a part-time 4WD and ECVT gearbox. Production is limited to 500 units per month because Van Doorne can only produce this much steel belt for them. In June, inventory increased to 3,000 per month and Subaru responded by installing extra volume into the transmission for their Rex microcar. In 1989 Justy became the first production car in the US to offer CVT technology. While Justy sees only limited success, Subaru continues to use CVT in kei cars to this day, while also supplying to other manufacturers. Subaru offers CVT (Lineartronic) in 2014 Outback, Legacy, Forester, Impreza, and Crosstrek.
In the summer of 1987, the Ford Fiesta and Fiat Uno became the first major European automaker to be equipped with steel-bonded CVT (as opposed to a less powerful rubber-belted DAF design). This CVT, Ford CTX was developed by Ford, Van Doorne, and Fiat, with transmission work starting in 1976.
Nissan March 1992 includes Nissan N-CVT based on Fuji Heavy Industrial ECVT. In the late 1990s, Nissan designed its own CVT that allowed higher torque and included a torque converter. This gearbox is used in a number of Japanese market models. Nissan is also the only car maker to bring roller-based CVT to the market in recent years. Their toroidal CVT, named Extroid, is available in the Japanese market Y34 Nissan Gloria and V35 Skyline GT-8. However, the gearbox did not get carried away when Cedric/Gloria was replaced by Nissan Fuga in 2004. Nissan Murano, introduced in 2003, and Nissan Rogue, introduced in 2007, also use CVT in their automatic transmission model. In a Nissan press release dated July 12, 2006, Nissan announced large-scale displacement to CVT transmissions when they selected XTronic CVT technology for all versions of Versa, Cube, Sentra, Altima and Maxima vehicles in North America, making the CVT mainstream transmission system. One of the main motivators for Nissan to switch to CVT is as part of their 'Green Program 2010' which aims to reduce CO 2 emissions by 2010. CVT found in Nissan Maxima, Murano and V6 Altima versions are considered as the world's first "3.5 L class" CVT belt and can withstand much higher torque loads than other belt CVTs.
After studying the pulley-based CVT for years, Honda also introduced their own version of the Honda Civic VTi 1995. Dubbed the Honda Multi Matic, the CVT gearbox receives much higher torque than traditional CVT pulleys, and also includes a torque converter for "creep" action. CVT is used in Honda City ZX produced in India and Honda City Vario manufactured in Pakistan.
In 1996, Fendt, a German-based tractor manufacturer, released the first heavy-duty tractor to be equipped with a hydrostatic type CVT with Fendt Vario 926. A year later Fendt was acquired by AGCO Corporation which expanded the use of transmission to Tractor Challenger, Massey Ferguson, and brand TerraGator engines, which are also owned by AGCO. More than 100,000 agricultural tractors have been produced with this transmission design.
Toyota used the Power Split Transmission (PST) in the 1997 Prius, and all subsequently sold Toyota and Lexus hybrids continue to use the system (marketed under the name Hybrid Synergy Drive). HSD is also referred to as electronically controlled continuously variable transmission (eCVT). PST allows either an electric motor or an internal combustion engine (ICE) or both to drive the vehicle. In ICE-only mode, parts of mechanical power are mechanically coupled to the drivetrain, with other parts through generators and motors. The amount of power supplied through the electrical path determines the effective gear ratio. Toyota also offers a non-hybrid CVT called Multidrive for models such as Avensis.
Audi, since 2000, offers CVT type chains (multitronic) as an option on some of the larger engine models, for example A4 3.0Ã, L V6.
Fiat in 2000 offered the CVT Cone-type as an option on the Fiat Punto hit model (16v 80 PS ELX, Sporting) and Lancia Y (1.2 16V).
BMW used the CVT belt-drive (produced by ZF Friedrichshafen) as an option for the MINI low and middle-range in 2001, leaving it only on supercharged versions of cars where increased torque levels demanded a conventional automatic gearbox. CVT can also be manually "shifted" if desired with software simulation shift points.
MG-Rover uses identical ZF CVT transmission on Rover 45 and MG ZS models.
GM introduced a CVT version known as VTi in 2002. It was used in the Saturn Vue and Saturn Ion models.
In 2002, the Suzuki Burgman 650 was the world's largest displacement scooter, and the first two-wheeled vehicle featuring an electrically controlled CVT.
Mercedes-Benz introduced their CVT Transmission version, known as "Autotronic" in 2004 for the 2005 model A-Class. And then in 2005 to model the 2006 B-Class. "Autotronic" is one of the most compact CVT Transmissions in the world.
Ford introduced the CVT driven by a chain known as the CFT30 at Ford Freestyle 2005, Ford Five Hundred, and Mercury Montego. The transmission is designed in collaboration with German automotive supplier ZF Friedrichshafen and was manufactured in Batavia, Ohio at Batavia Transmissions LLC (subsidiary Ford Motor Company) until March 22, 2007. The Batavia factory also manufactures a belt-driven CVT CFT23 which enters the Ford Focus C-MAX, which does not have much success due to the failure of the gearbox, because it is incorporated with a 1.6 TDCi turbodiesel engine, which has a higher torque rating than the CVT can handle. Ford also sold Escort and Orion models in Europe with the CVT in the 1980s and 1990s.
The contract agreement was made in 2005 between MTD and Torotrak Products for the first full toroidal system to be produced for outside electrical equipment such as jet ski, ski-car and cutting machine.
The 2007 Caliber Dodge and related Jeep Compass and Jeep Patriot use CVT using a variable pulley system as their optional automatic transmission.
The Mitsubishi Lancer 2008 model is available with CVT transmission as an automatic transmission. DE and ES models receive standard CVT with Drive and Low gear; the GTS model comes with Standard Drive and also Sportronic mode which allows the driver to use 6 different preset gear ratios (either with shifters or padded steering-mounted shifters).
SEAT Exeo 2009 is available with CVT (multitronic) automatic transmission as an option for 2.0 TSI petrol engine 200 hp (149 kW), with a "six speed" option.
In 2010, the US Patent Office issued the patent number 7,647,768 B1 for a series of hydraulic torque converters using hydraulic friction rather than mechanical friction as CVT.
Suzuki has been using CVT since 2010 on their SX4 and Kizashi models.
In 2016, FCA US LLC announces Chrysler Pacifica 2017 minivan using CVT instead of the 9-speed automatic found in gasoline versions.
For Toyota Corolla Hatchback Toyota 2019 creates a new CVT with a "launch gear" or a physical 1st gear from a conventional automatic transmission along with a CVT pulleys. From 0-25 mph transmission will remain at this launch wheel to help accelerate from stop and increase CVT durability. After 25 mph, the transmission will switch to the CVT pulley.
Marketing name
- Lineartronic: Subaru
- Xtronic Jatco: Nissan, Renault
- K CVT, CVTi, eCVT: Toyota
- INVECS-III: Mitsubishi
- Multitronic: Volkswagen, Audi
See also
Constant Speed ​​DriveNote
References
External links
- John Kelly: CVT Transaxle Steel Push Belt Construction (YouTube), Weber State University, Odgen, 2017
Source of the article : Wikipedia
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