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153-417: HSD technology produces a full hybrid vehicle which allows the car to run on the electric motor only, as opposed to most other brand hybrids which cannot and are considered mild hybrids . The HSD also combines an electric drive and a planetary gearset which performs similarly to a continuously variable transmission . The Synergy Drive is a drive-by-wire system with no direct mechanical connection between

306-471: A battery (or supercapacitor ) supplemented by an internal combustion engine (ICE) that can either recharge the batteries or power the vehicle. Other hybrid powertrains can use flywheels to store energy. Among different types of hybrid vehicles, only the electric/ICE type is commercially available as of 2017. One variety operated in parallel to provide power from both motors simultaneously. Another operated in series with one source exclusively providing

459-516: A centrifugal clutch , to assist when idling or manually reversing the scooter. The 1974 Rokon RT340 TCR Automatic off-road motorcycle was fitted with a snowmobile CVT. The first ATV equipped with a CVT was the Polaris Trail Boss in 1985. Combine harvesters used variable belt drives as early as the 1950s. Many small tractors and self-propelled mowers for home and garden use simple rubber belt CVTs. Hydrostatic CVTs are more common on

612-444: A clutch , or automatic, with a torque converter , but both allow the engine and the wheels to rotate at different speeds. The driver can adjust the speed and torque delivered by the engine with the accelerator and the transmission mechanically transmits nearly all of the available power to the wheels which rotate at a different rate than the engine, by a factor equal to the gear ratio for the currently selected gear. However, there are

765-419: A continuously variable transmission (CVT), except that the torque/speed conversion uses an electric motor rather than a direct mechanical gear train connection. An HSD car cannot operate without the computer, power electronics, battery pack, and motor-generators, though in principle it could operate while missing the internal combustion engine. (See: Plug-in hybrid ) In practice, HSD equipped cars can be driven

918-462: A diesel–electric locomotive with the addition of a battery that may power the vehicle without running the ICE and acting as an energy buffer that is used to accelerate and achieve greater speed; the generator may simultaneously charge the battery and power the electric motor that moves the vehicle. When the vehicle is stopped the ICE is switched off without idling, while the battery provides whatever power

1071-487: A one-way clutch on the planetary gear carrier of the second planetary gearset. By selectively engaging these, the transmission can simulate ten different gear ratios. The fifth generation Hybrid Synergy Drive transaxle is similar to the prior generation, with detail improvements making the electric motors lighter, more compact, and more powerful. The following is a list of vehicles with Hybrid Synergy Drive and related technologies (Toyota Hybrid System): As of autumn 2005,

1224-406: A ravigneaux-type gear with four shafts, two of which can be held still alternatively by a brake/clutch. The GS 450h and LS 600h systems utilized rear-wheel drive and all-wheel drive drivetrains, respectively, and were designed to be more powerful than non-hybrid versions of the same model lines, while providing comparable engine class efficiency. A simplified version was released in 2012 with

1377-455: A 27% improvement in combined fuel efficiency in EPA testing of the 2009 Saturn VUE. The system can also be found on the 2008–2009 Saturn Aura Green Line and the 2008–2010 Chevrolet Malibu hybrids. Another way to offer start/stop is by employing a static start engine. Such an engine requires no starter motor, but employs sensors to determine the exact position of each piston, then precisely timing

1530-538: A CVT), but in practice, there are many similarities in operation, and a ratcheting CVT is able to produce a zero-output speed from any given input speed (as per an Infinitely Variable Transmission). The drive ratio is adjusted by changing linkage geometry within the oscillating elements so that the summed maximum linkage speed is adjusted, even when the average linkage speed remains constant. Ratcheting CVTs can transfer substantial torque because their static friction actually increases relative to torque throughput, so slippage

1683-552: A Paice patent, Toyota invented, designed and developed the Prius and Toyota’s hybrid technology independent of any inventions of Dr. Severinsky and Paice as part of Toyota’s long history of innovation". Paice earlier entered into an agreement with Ford for the license of Paice's patent. Full hybrid Hybrid vehicle drivetrains transmit power to the driving wheels for hybrid vehicles . A hybrid vehicle has multiple forms of motive power, and can come in many configurations. For example,

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1836-438: A battery large enough to operate the electrical system and ignite the engine. Electrical vehicles have a long history combining internal combustion and electrical transmission – as in a diesel–electric power-train – although they have mostly been used for rail locomotives . A diesel–electric powertrain fails the strict definition of hybrid because the electric drive transmission directly replaces

1989-429: A compound-split design, since the addition of four clutches within the transmission allows for multiple configurations of engine power-splitting. In addition to the clutches, this transmission has a second planetary gearset. The objective of the design is to vary the percentage of mechanically vs. electrically transmitted power to cope both with low-speed and high-speed operating conditions. This enables smaller motors to do

2142-475: A computer that's solely dedicated to keeping the battery at the optimum temperature and optimum charge level. Like the second generation Prius, the third generation Prius battery pack is made up of the same type of 1.2 volt cells. It has 28 modules of 6 cells for a total nominal voltage of only 201.6 volts. A boost converter is used to produce 500 volt DC supply voltage for the inverters for MG1 and MG2. The car's electronics only allow 40% of total rated capacity of

2295-504: A constant/narrow band offsets many of the perceived disadvantages of the Wankel engine in automotive applications. ) The electric propeller motor uses electricity stored in batteries, with the engines not operating, to take off and climb reducing sound emissions. The powertrain reduces the weight of the plane by 100 kilos relative to its predecessor. The DA36 E-Star first flew in June 2013, making this

2448-622: A continuous, gradual improvement in the specific capacity of the traction battery. The original Prius used shrink-wrapped 1.2 volt D cells, and all subsequent THS/HSD vehicles have used custom 7.2 V battery modules mounted in a carrier. In 2001, a modified version of the Generation 1 THS transaxle was released in the Japanese domestic market as the P210 transaxle, fitted to the Estima minivan. The P210 couples

2601-414: A continuously variable transmission allows the driver (or the automobile computer) to effectively select the optimal gear ratio required for any desired speed or power. The transmission is not limited to a fixed set of gears. This lack of constraint frees the engine to operate at its optimal brake-specific fuel consumption . An HSD vehicle will typically run the engine at its optimal efficiency whenever power

2754-462: A controllable torque transfer unit ( US patent 5343970 , Severinsky; Alex J., "Hybrid electric vehicle", issued 1994-09-06   ) and has additional patents related to hybrid vehicles. In 2010 Toyota agreed to license Paice's patents; terms of the settlement were not disclosed. In the settlement "The parties agree that, although certain Toyota vehicles have been found to be equivalent to

2907-647: A court in Düsseldorf had ruled that the Toyota Prius driveline and the Lexus RX 400h driveline do not breach the Antonov hybrid CVT patent. Ford Motor Company independently developed a system with key technologies similar to Toyota's HSD technology in 2004. As a result, Ford licensed 21 patents from Toyota in exchange for patents relating to emissions technology. Paice LLC received a patent for an improved hybrid vehicle with

3060-449: A hybrid may receive its energy by burning gasoline, but switch between an electric motor and a combustion engine . A typical powertrain includes all of the components used to transform stored potential energy . Powertrains may either use chemical, solar, nuclear or kinetic energy for propulsion. The oldest example is the steam locomotive. Modern examples include electric bicycles and hybrid electric vehicles , which generally combine

3213-491: A hydrostatic CVT in the form of a variable-displacement axial piston pump with a variable-angle swashplate . A cone CVT varies the drive ratio by moving a wheel or belt along the axis of one or more conical rollers. The simplest type of cone CVT, the single-cone version, uses a wheel that moves along the slope of the cone, creating variation between the narrow and wide diameters of the cone. Some cone CVT designs use two rollers. In 1903, William Evans and Paul Knauf applied for

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3366-432: A hydrostatic CVT include: Disadvantages of a hydrostatic CVT include: Uses of hydrostatic CVTs include forage harvesters , combine harvesters , small wheeled/tracked/skid-steer loaders , crawler tractors , and road rollers .  One agricultural example, produced by AGCO , splits power between hydrostatic and mechanical transfer to the output shaft via a planetary gear in the forward direction of travel (in reverse,

3519-414: A hydrostatic CVT, the effective "gear ratio" between the engine and the driving wheel(s) is the result of a difference between the pump's displacement—expressed as cubic inches or cubic centimeters per revolution—and the motor's displacement. In a closed system, that is, a system in which all of the pump's output is delivered to the motor(s), this ratio is given by the equation GR = Dm ÷ Dp , where Dp

3672-641: A levy on each vehicle sold, which could make the hybrid SUV less competitive. Toyota fought back by seeking to officially invalidate Antonov's relevant patents. The court motion in Microsoft Word document format can be read here. On 1 September 2006 Antonov announced that the Federal Patent Court in Munich has not upheld the validity of the German part of Antonov's patent (EP0414782) against Toyota. A few days later,

3825-481: A limited number of "gears" or gear ratios that the driver can choose from, typically four to six. This limited gear-ratio set forces the engine crankshaft to rotate at speeds where the ICE is less efficient, i.e., where a liter of fuel produces fewer joules. Optimal engine speed-torque requirements for different vehicle driving and acceleration conditions can be gauged by limiting either tachometer RPM rate or engine noise in comparison with actual speed. When an engine

3978-414: A mile or two without gasoline, as an emergency measure to reach a gas station . An HSD transaxle contains a planetary gear set that adjusts and blends the amount of torque from the engine and motor(s) as it's needed by the front wheels. It is a sophisticated and complicated combination of gearing, electrical motor-generators, and computer-controlled electronic controls. One of the motor-generators, MG2,

4131-448: A millimeter thick. The conical pulleys have radial grooves. A groove on one side of the pulley is met with a ridge on the other side and so the sliding plates are pushed back and forth to conform to the pattern, effectively forming teeth of the correct pitch when squeezed between the pulleys. Due to the interlocking surfaces, this type of drive can transmit significant torque and so has been widely used in industrial applications. However,

4284-526: A multi-plate clutch, not a torque converter , to prevent idle creep . Use of CVTs then spread in the following years to models including the 1998 Nissan Cube , 1999 Rover 25 and 1999 Audi A6 . The 1999 Nissan Cedric (Y34) used a toroidal CVT—unlike the pulley-based designs used by other manufacturers—marketed as the Nissan Extroid , which incorporated a torque converter. Nissan then switched from toroidal to pulley-based CVTs in 2003. The version of

4437-412: A normal geared transmission with an electromechanical system. An internal combustion engine (ICE) delivers power most efficiently over a small speed range, but the wheels need to be driven over the vehicle's full speed range. In a conventional automobile the geared transmission delivers different discrete engine speed-torque power requirements to the wheels. Geared transmissions may be manual, with

4590-414: A parallel hybrid architecture. An alternative parallel hybrid is the "through the road" type. In this system a conventional drivetrain powers one axle, with an electric motor or motors driving another. This arrangement was used by the earliest 'off track' trolleybuses. It in effect provides a complete backup power train. In modern motors batteries can be recharged through regenerative braking or by loading

4743-546: A parallel hybrid with start-stop and modest levels of engine-assist or regenerative braking. Mild hybrids generally cannot provide all-electric propulsion. Mild hybrids like the General Motors 2004–2007 Parallel Hybrid Truck (PHT) and the Honda Eco-Assist hybrids are equipped with a three-phase electric motor mounted within the bell-housing between the engine and transmission, allowing the engine to be turned off whenever

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4896-408: A patent on a continuously variable transmission using two parallel conical rollers pointing in opposite directions and connected by belts that could be slid along the cones to vary the transmission ratio. The Evans Variable Speed Countershaft, produced in the 1920s, is simpler—the two rollers are arranged with a small constant-width gap between them, and the position of a leather cord that runs between

5049-427: A power-split hybrid, a smaller, less flexible, and more efficient engine can be used. The conventional Otto cycle (higher power density, more low-RPM torque, lower fuel efficiency ) is often modified to an Atkinson cycle or Miller cycle (lower power density, less low-rpm torque, higher fuel efficiency; sometimes called an Atkinson-Miller cycle). The smaller engine, using a more efficient cycle and often operating in

5202-465: A pulley-based CVT. In some toroidal systems, the direction of thrust can be reversed within the CVT, removing the need for an external device to provide a reverse gear. A ratcheting CVT uses a series of one-way clutches or ratchets that rectify and sum only "forward" motion. The on-off characteristics of a typical ratchet means that many of these designs are not continuous in operation (i.e. technically not

5355-557: A reduction in size and combined weight. The traction motor itself is considerably more compact and gains a better power-to-weight ratio . Notably there is a 20 percent reduction in mechanical losses due to friction compared to the previous model. The 2012– Prius c retains the P510 transaxle. The P610 transaxle employs helical gears rather than the straight-cut spur gears employed in the earlier transaxles, and which run more smoothly and quietly, while also accommodating higher mechanical loads. With

5508-414: A ring of steel pole pieces between them to create a planetary gearset using magnets. It is claimed to produce a 3 to 5 percent reduction in fuel consumption compared to a mechanical system. Some CVTs can also function as an infinitely variable transmission (IVT) which offers an infinite range of low gears (e.g. moving a vehicle forward at an infinitely slow speed). Some IVTs prevent back driving (where

5661-410: A series of discs and rollers. The discs can be pictured as two almost-conical parts arranged point-to-point, with the sides dished such that the two parts could fit into the central hole of a torus . One disc is the input, and the other is the output. Between the discs are rollers, which vary the ratio and transfer power from one side to the other. When the rollers' axes are perpendicular to the axis of

5814-457: A specific level of driver involvement with the vehicles. Many small vehicles—such as snowmobiles , golf carts , and motor scooters —use CVTs, typically of the pulley variety. CVTs in these vehicles often use a rubber belt with a non-stretching fixed circumference manufactured using various highly durable and flexible materials, due to the mechanical simplicity and ease of use outweighing their comparative inefficiency. Some motor scooters include

5967-412: A storage battery through an inverter. Although MG1 typically operates as a generator (alternator), it also serves as the starter motor for the internal combustion engine. MG2 usually acts as a motor, either by itself at low speeds or to assist the internal combustion engine, but MG2 also can act as a generator, for instance, during deceleration for regenerative braking . Schematically, MG1 is connected to

6120-737: A system named "Two-Mode Hybrid" as part of the Global Hybrid Cooperation . The technology was released in the fall of 2007 on the Chevrolet Tahoe Hybrid . The system was also featured on the GMC Graphite SUV concept vehicle at the 2005 North American International Auto Show in Detroit . BYD Auto 's F3DM sedan is a series-parallel plug-in hybrid automobile, which went on sale in China in 2008. The Two-Mode Hybrid name highlights

6273-409: A vehicle giving superior weight distribution and maximizing vehicle cabin space and opening up the possibility of superior vehicle designs exploiting this flexibility. Power-split hybrid or series-parallel hybrid are parallel hybrids that incorporate power-split devices, allowing for power paths from the ICE to the wheels that can be either mechanical or electrical. The main principle is to decouple

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6426-471: A wheel directly eliminates the conventional mechanical transmission elements: gearbox, transmission shafts and differential, and can sometimes eliminate flexible couplings . In 1997, Toyota released the first series-hybrid bus sold in Japan. Designline International of Ashburton, New Zealand produces city buses with a microturbine powered series-hybrid system. Wrightbus produces series hybrid buses including

6579-407: A wide speed range. ICEs are most efficient when turning at a constant speed. ICEs can run optimally when turning a generator. Series-hybrid systems offer smoother acceleration by avoiding gear changes. Series-hybrids incorporate: In addition: The electric motor may be entirely fed by electricity from the battery or via the generator turned by the ICE, or both. Such a vehicle conceptually resembles

6732-435: Is a transversal categorization. Micro hybrid is a general term given to vehicles that use some type of start-stop system to automatically shut off the engine when idling . Strictly speaking, micro hybrids are not real hybrid vehicles, because they do not rely on two different sources of power. Mild hybrids are essentially conventional vehicles with some hybrid hardware, but with limited hybrid features. Typically, they are

6885-409: Is connected to the output shaft, and thus couples torque into or out of the drive shafts; feeding electricity into MG2 adds torque at the wheels. The engine end of the drive shaft has a second differential ; one leg of this differential is attached to the internal combustion engine and the other leg is attached to a second motor-generator, MG1. The differential relates the rotation speed of the wheels to

7038-429: Is eliminated. The aim is to reduce fuel consumption and emissions by up to 25 percent. An onboard 40 hp (30 kW) Austro Engine Wankel rotary engine and generator provides the electricity. The Wankel was chosen because of its small size, low weight and great power to weight ratio. (Wankel engines also run efficiently at a constant speed of approximately 2,000 RPM which is suited to generator operation. Keeping to

7191-433: Is impossible in properly designed systems. Efficiency is generally high because most of the dynamic friction is caused by very slight transitional clutch speed changes. The drawback to ratcheting CVTs is the vibration caused by the successive transition in speed required to accelerate the element, which must supplant the previously operating and decelerating power-transmitting element. The design principle dates back to before

7344-423: Is needed at rest. Vehicles at traffic lights, or in slow moving stop-start traffic need not burn fuel when stationary or moving slowly, reducing emissions. Series-hybrids can be fitted with a supercapacitor or a flywheel to store regenerative braking energy, which can improve efficiency by recovering energy otherwise lost as heat through the braking system. Because a series-hybrid has no mechanical link between

7497-480: Is needed to charge batteries or accelerate the car, shutting down the engine entirely when less power is required. Like a CVT , an HSD transmission continuously adjusts the effective gear ratio between the engine and the wheels to maintain the engine speed while the wheels increase their rotational speed during acceleration. This is why Toyota describes HSD-equipped vehicles as having an e-CVT ( electronic continuously variable transmission ) when required to classify

7650-553: Is not uncommon, especially for extended drives at modest speeds (a longer drive allows the engine to warm up fully). This is approximately twice the fuel efficiency of a similarly equipped four-door sedan with a conventional power train. Not all of the extra efficiency of the Prius is due to the HSD system: the Atkinson cycle engine itself was also designed specifically to minimize engine drag via an offset crankshaft to minimize piston drag during

7803-433: Is outfitted with 4.4 kWh lithium-ion batteries co-developed with Panasonic that weighs 80 kg (180 lb) compared with the nickel-metal hydride battery of the third generation Prius , which has a capacity of only 1.3 kWh, and weighs 42 kg (93 lb). The larger battery pack enables all-electric operation at higher speeds and longer distances than the conventional Prius hybrid. The following table details

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7956-467: Is required to operate efficiently across a broad RPM range, due to its coupling to a geared transmission, manufacturers are limited in their options for improving engine efficiency , reliability, or lifespan, as well as reducing the size or weight of the engine. This is why the engine for an engine-generator is often much smaller, more efficient, more reliable, and longer life than one designed for an automobile or other variable speed application. However,

8109-519: Is the Fisker Karma . The Chevrolet Volt is almost a series hybrid, but also includes a mechanical link from the engine to the wheels above 70 mph. Series-hybrids have been taken up by the aircraft industry. The DA36 E-Star, an aircraft designed by Siemens , Diamond Aircraft and EADS , employs a series hybrid powertrain with the propeller turned by a Siemens 70 kW (94 hp) electric motor. A power sapping propeller speed reduction unit

8262-400: Is the pump's effective displacement, Dm is the motor's displacement, and GR is the "gear ratio." In a hydrostatic CVT, the effective "gear ratio" is varied by varying effective displacement of the pump, which will vary the volume of oil delivered to the motor(s) at a given engine speed (RPM).  There are several ways in which this may be accomplished, one being to divert some of

8415-478: The California Air Resources Board . Electric transmissions were invented by 1903. Mechanical transmissions involve costs via their weight, bulk, noise, cost, complexity and drain on engine power with every gear-change, affecting both manual and automatic systems. Unlike ICEs, electric motors typically do not require a transmission. Compared to parallel hybrids, the mechanical transmission between

8568-591: The Ford Escape Hybrid . Toyota CEO Katsuaki Watanabe said in a February 16, 2007 interview that Toyota was "aiming at reducing, by half, both the size and cost of the third-generation HSD system". The new system will feature lithium-ion batteries in later years. Lithium-ion batteries have a higher energy capacity-to-weight ratio compared to NiMH , but operate at higher temperatures, and are subject to thermal instability if not properly manufactured and controlled, raising safety concerns. In 2005, vehicles such as

8721-511: The Gemini 2 and New Routemaster . Supercapacitors combined with a lithium ion battery bank have been used by AFS Trinity in a converted Saturn Vue SUV vehicle. Using supercapacitors they claim up to 150 mpg in a series-hybrid arrangement. Well known automotive series hybrid models include the variant of the BMW i3 that is equipped with a range extender. Another example of a series hybrid automobile

8874-549: The Volvo V60 plug-in hybrid , the BMW 2 Series Active Tourer , BMW i8 and the second generation Honda NSX . Series hybrids are also referred to as extended-range electric vehicles (EREV) or range-extended electric vehicles (REEV), or electric vehicle with extended range (EVER). All series hybrids are EREV, REEV or EVER, but not all EREV, REEV or EVER are series hybrids. Series hybrids with particular characteristics are classified as range-extended battery-electric vehicle (BEVx) by

9027-595: The fourteenth generation Crown (S210) ; the L210 transmission omits the two clutches but retains the second planetary gearset (MSRD) applied to the output of MG2, in common with other Generation 3 transaxles. However, compared to the G3 transaxles, instead of coupling the two ring gears, the L210 couples the PSD ring gear to the MSRD planetary gear carrier, and grounds the ring gear of the MSRD instead of

9180-556: The power stroke , and a unique intake system to prevent drag caused by manifold vacuum ("pumping losses") versus the normal Otto cycle in most engines. Furthermore, the Atkinson cycle recovers more energy per cycle than the Otto because of its longer power stroke. The downside of the Atkinson cycle is much reduced torque, particularly at low speed; but the HSD has enormous low-speed torque available from MG2. The Highlander Hybrid (also sold as

9333-486: The unsprung mass of the wheel assembly; vehicle designs may be optimized to lower the centre of gravity by locating heavier elements (including battery) at floor level; In a typical road vehicle the power-transmission setup may be smaller and lighter than the equivalent conventional mechanical power-transmission setup, liberating space; the combustion generator set only requires cables to the driving electric motors, increasing flexibility in major component layout spread across

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9486-502: The 1930s, with the original design intended to convert rotary motion to oscillating motion and back to rotary motion using roller clutches. This design remains in production as of 2017, for use with low-speed electric motors. An example prototyped as a bicycle transmission was patented in 1994. The operating principle for a ratcheting CVT design, using a Scotch yoke mechanism to convert rotary motion to oscillating motion and non-circular gears to achieve uniform input to output ratio,

9639-410: The 1950s. CVTs with flywheels are used as a speed governor between an engine (e.g. a wind turbine) and the electric generator . When the engine is producing sufficient power, the generator is connected directly to the CVT which serves to regulate the engine's speed. When the power output is too low, the generator is disconnected, and the energy is stored in the flywheel. It is only when the speed of

9792-680: The Antonov Automotive Technology BV Plc company has sued Toyota , the Lexus brand mother company, over alleged patent infringement relating to key components in the RX 400h's drivetrain and the Toyota Prius hybrid compact car. The case has been pending in secret since April 2005, but settlement negotiations did not bring a mutually acceptable result. Antonov eventually took legal recourse in the German court system, where decisions are usually made relatively swiftly. The patent holder seeks to impose

9945-549: The CVT available in the Rex kei car . Subaru has also supplied its CVTs to other manufacturers (e.g., the 1992 Nissan Micra and Fiat Uno and Panda ). Also in 1987, second-generation Ford Fiesta and first-generation Fiat Uno were introduced with steel-belted CVTs, which are called CTX and Unomatic in Ford and Fiat, respectively. The 1996 sixth-generation Honda Civic introduced a pulley-based Honda Multi Matic (HMM) CVT which included

10098-449: The CVT used with the VQ35DE engine in the fourth-generation Nissan Altima is claimed to be capable of transmitting higher torque loads than other belt CVTs. The 2019 Toyota Corolla (E210) is available with a CVT assisted by a physical "launch gear" alongside the CVT pulley. At speeds of up to 40 km/h (25 mph), the launch gear is used to increase acceleration and reduce stress on

10251-653: The CVT. Above this speed, the transmission switches over to the CVT. Marketing terms for CVTs include "Lineartronic" ( Subaru ), "Xtronic" ( Jatco , Nissan , Renault ), INVECS-III ( Mitsubishi ), Multitronic ( Volkswagen , Audi ), "Autotronic" ( Mercedes-Benz ) and "IVT" ( Hyundai , Kia ). In the United States, Formula 500 open-wheel racing cars have used CVTs since the early 1970s. CVTs were prohibited from Formula One in 1994 (along with several other electronic systems and driving aids) due to concerns over escalating research and development costs and maintaining

10404-509: The Estima was released at the same time; the Q410 rear drive unit uses an electric traction motor with no mechanical coupling to the front transaxle. THS was followed by THS-II in the 2004 Prius. Starting with THS-II, Toyota also began referring to the system as Hybrid Synergy Drive (HSD). Compared to THS, THS-II offered reduced consumption and better performance with increased power and torque. THS-II uses

10557-474: The Fourth Generation HSD, Toyota is also offering a four-wheel drive option, dubbed "E-Four", similar to the 2005 RX400h and Highlander Hybrid, in which an electric traction motor is added to the rear, but is not mechanically coupled to the internal combustion engine or front inverter. In fact, the "E-Four" system has its own rear inverter, although this inverter draws power from the same hybrid battery as

10710-530: The Generation 3 HSD as it provides for a smaller, yet more powerful MG2. However, a secondary benefit is the MG1 will not be driven into overspeed as frequently, and which would otherwise mandate employing the ICE to mitigate this overspeed; this strategy improves HSD performance as well as saving fuel and wear-and-tear on the ICE. The HSD system has two principal battery packs, the High Voltage (HV) battery, also known as

10863-447: The HSD powered car significant efficiency advantages—particularly in city driving. The HSD operates in distinct phases depending on speed and demanded torque. Here are a few of them: The Toyota Prius has modest acceleration but has extremely high efficiency for a midsized four-door sedan: usually significantly better than 40 mpg (US) (5.9 L/100 km) is typical of brief city jaunts; 55 mpg (4.3 L/100 km)

11016-622: The HV battery capacity for several Lexus and Toyota vehicles. The HSD drive works by shunting electrical power between the two motor generators, running off the battery pack, to even out the load on the internal combustion engine. Since a power boost from the electrical motors is available for periods of rapid acceleration, the ICE can be downsized to match only the average load on the car, rather than sized by peak power demands for rapid acceleration. The smaller internal combustion engine can be designed to run more efficiently. Furthermore, during normal operation

11169-481: The Highlander Hybrid rates between 27 and 31 mpg (8.7–7.6 L/100 km). A conventional Highlander is rated by the EPA with 19 city, 25 highway mpg (12.4 and 9.4 L/100 km respectively). The HSD mileage boost depends on using the gasoline engine as efficiently as possible, which requires: Most HSD systems have batteries that are sized for maximal boost during a single acceleration from zero to

11322-430: The ICE and the wheels, the engine can run at a constant and efficient rate regardless of vehicle speed, achieving higher efficiency (37%, rather than the ICE average of 20% ) and at low or mixed speeds this could result in ~50% increase in overall efficiency (19% vs 29%). Lotus offered an engine/generator set design that runs at two speeds, giving 15 kW of electrical power at 1,500 rpm and 35 kW at 3,500 rpm via

11475-499: The ICE can also act as a generator for supplemental recharging. This makes them more efficient in urban 'stop-and-go' conditions. They use a smaller battery pack than other hybrids. Honda 's early Insight, Civic , and Accord hybrids using IMA are examples of production parallel hybrids. General Motors Parallel Hybrid Truck (PHT) and BAS Hybrids such as the Saturn Vue and Aura Greenline and Chevrolet Malibu hybrids also employ

11628-750: The ICE/MG1 and the MG2 have separate reduction paths, and are combined in a "compound" gear which is connected to the final reduction gear train and differential; it was introduced on all-wheel drive and rear-wheel drive Lexus models. By May 2007 Toyota had sold one million hybrids worldwide; two million by the end of August 2009; and passed the 5 million mark in March 2013. As of September 2014, more than 7 million Lexus and Toyota hybrids had been sold worldwide. The United States accounted for 38% of TMC global hybrid sales as of March 2013. Toyota's HSD system replaces

11781-468: The Kluger in some countries) offers better acceleration performance compared to its non-hybrid version. The hybrid version goes from 0–60 mph in 7.2 seconds, trimming almost a second off the conventional version's time. Net power is 268 hp (200 kW) compared to the conventional 215 hp (160 kW). Top speed for all Highlanders is limited to 112 mph (180 km/h). Typical fuel economy for

11934-558: The Lexus Hybrid Drive name, was fitted to the Lexus GS 450h / LS 600h sedans as the L110 transmission. Previous versions of HSD/THS were fitted to transaxles used with front-wheel drive platforms; Lexus Hybrid Drive applied the two-motor HSD concept to a longitudinal transmission for rear-wheel drive vehicles. This system uses two clutches (or brakes) to switch the second motor's gear ratio to

12087-402: The Lexus RX 400h and Toyota Highlander Hybrid added four-wheel drive operation by adding a third electric motor ("MGR") on the rear axle. In this system, the rear axle is purely electrically powered, and there is no mechanical link between the engine and the rear wheels. This also permits regenerative braking on the rear wheels. In 2006 and 2007, a further development of the HSD drivetrain, under

12240-476: The Motor Speed Reduction Device (MSRD); it is compounded with the first planetary gearset (PSD) by coupling the two ring gears together. The coupled ring gears are still used to drive the front wheels of the vehicle. The traction motor (MG2) uses the MSRD as a reduction gear, making it possible to increase the power density of the motor. Ford has also developed a similar hybrid system, introduced in

12393-453: The Prius c). The Generation 4 HSD eliminates the second planetary gear set, and places the electric motors on parallel axes, with a combining gear in between these axes, and transfers the combined result to the final drive differential. This is quite similar to Toyota-affiliated Aisin Seiki 's hybrid system, and saves significant space. General Motors , BMW , and DaimlerChrysler collaborated on

12546-584: The Reeves CVT was also used by several other manufacturers. The 1911 Zenith Gradua 6HP motorcycle used a pulley-based Gradua CVT. A year later, the Rudge-Whitworth Multigear was released with a similar but improved CVT. Other early cars to use a CVT were the 1913–1923 David small three-wheeled cyclecars built in Spain, the 1923 Clyno built in the U.K., and the 1926 Constantinesco Saloon built in

12699-486: The Toyota brand ( Lexus ; the HSD-derived systems used in Lexus vehicles have been termed Lexus Hybrid Drive ), was implemented in the 2006 Camry and Highlander, and would eventually be implemented in the 2010 "third generation" Prius , and the 2012 Prius c . The Toyota Hybrid System is designed for increased power and efficiency, and also improved "scalability" (adaptability to larger as well as smaller vehicles), wherein

12852-677: The U.K. The first mass-production car to use a CVT was the 1958 DAF 600 from the Netherlands . Its Variomatic transmission was used in several vehicles built by DAF and Volvo until the 1980s. In 1987, the ECVT , the first electronically controlled steel-belted CVT, was introduced as an optional transmission on the Subaru Justy , Production was limited to 500 units per month due to Van Doorne's limited production output. In June of that year, supplies increased to 3,000 per month, leading Subaru to make

13005-501: The battery is exhausted and the car can achieve only 55–60 mph on the same slope. (until the battery is recharged by driving under less demanding circumstances) The design of the Toyota Hybrid System ;/ Hybrid Synergy Drive has now had five generations since the original 1997 Japanese-market Toyota Prius. The power train has the same basic features, but there have been a number of significant refinements. The system

13158-662: The battery pack (6.5 ampere-hour) to be used in order to prolong the battery life. As a result, the SoC is allowed to vary only between 40% and 80% of the rated full charge. The battery used in the Highlander Hybrid and the Lexus RX 400h was packaged in a different metal battery casing with 240 cells that deliver high voltage of 288 volts. A button labelled "EV" maintains electric vehicle mode after being powered on and under most low-load conditions at less than 25 mph (40 km/h) if

13311-644: The battery, which can also be charged from external sources. Nissan 's e-Power line ( Note , Serena , Kicks , X-Trail , and Qashqai ) using the engine to drive a generator and the EM57 traction motor. Mazda 's MX-30 , is optionally equipped with a range extender. BMW's i3 attached the generator only to the battery. ThunderVolt hybrid transit buses and transit buses fitted with BAE Systems (formerly Lockheed Martin ) HybriDrive powertrains are also serial hybrids. Electric motors are more efficient than ICEs, with high power-to-weight ratios providing torque over

13464-424: The car or both coupled up jointly giving drive. This is the most common hybrid system as of 2016. If they are joined at an axis (in parallel) , the speeds at this axis must be identical and the supplied torques will add together (most electric bicycles are of this type). When only one of the two sources is in use, the other must be connected via a one-way clutch or freewheel so it can rotate freely. With cars

13617-437: The car's internal combustion engine and run accessories when the engine is not running. The alternator is used to recharge the battery and run the accessories when the engine is running. The HSD system replaces the geared transmission, alternator, and starter motor with: Through the power splitter, a series-parallel full hybrid's HSD system thus allows for the following intelligent power flows: The mechanical gearing design of

13770-424: The central sun gear (S), the internal combustion engine is connected to the planetary gear carrier (P) and not to any individual gear, and MG2 is connected to the ring gear (R). The wheels are connected to the ring gear through appropriate reduction gearing and a differential, not illustrated in the diagram. The Toyota Hybrid System uses a high-voltage battery pack, ranging between 276 and 288 V. There has been

13923-508: The contribution of power from the electric motor and the internal combustion engine. These differ from standard CVTs in that they are powered by an electric motor in addition to the engine, often using planetary gears to combine their outputs instead of a belt used in traditional CVTs. A notable example is the Toyota Hybrid Synergy Drive . Friction-disk transmissions were used in several vehicles and small locomotives built in

14076-420: The conventional engine-driven type. This removes the need to continuously run the engine when cabin cooling is required. Two positive temperature coefficient heaters are fitted in the heater core to supplement the heat provided by the engine. The updated version of HSD first delivered in the model year 2006 RX 400h is similar to THS/THS-II, with the addition of a second planetary gearset, which Toyota calls

14229-428: The different motors are at providing motive power: the ICE may be dominant (engaging the electric motor only in specific circumstances) or vice versa; while in others can run on the electric system alone but because current parallel hybrids are unable to provide electric-only or internal combustion-only modes they are often categorized as mild hybrids (see below). Parallel hybrids rely more on regenerative braking and

14382-415: The discs, the effective diameter is the same for the input discs and the output discs, resulting in a 1:1 drive ratio. For other ratios, the rollers are rotated along the surfaces of the discs so that they are in contact with the discs at points with different diameters, resulting in a drive ratio of something other than 1:1. An advantage of a toroidal CVT is the ability to withstand higher torque loads than

14535-400: The drive shafts, for feedback to the control computer. In Generation 1 and Generation 2 HSDs, MG2 is directly connected to the ring gear, that is, a 1:1 ratio, and which offers no torque multiplication, whereas in Generation 3 HSDs, MG2 is connected to the ring gear through a 2.5:1 planetary gear set, and which, consequently, offers a 2.5:1 torque multiplication, this being a primary benefit of

14688-415: The drive-train's ability to operate in all-electric (Mode 1, or Input-Split ) as well as hybrid (Mode 2, or Compound-Split ) modes. The design allows for operation in more than two modes. Two power-split modes are available, along with several fixed-gear (essentially parallel hybrid) regimes. Such a design can be referred to as a multi-regime design. The Two-Mode Hybrid powertrain design can be classified as

14841-550: The early 20th century in racing cars, including the Lohner–Porsche Mixte Hybrid . Porsche named the system System Mixte, which had a wheel hub motor arrangement, with a motor in each of the two front wheels, setting speed records. This approach isolates the engine from demand, allowing it to operate only at its most efficient speed. The engine can be much smaller, since it does not have to accommodate high speed/acceleration. Traction motors are typically powered only by

14994-455: The early 20th century, including the Lambert and Metz automobiles. Used today in snow blowers , these transmissions consist of an output disk that is moved across the surface of the input disk upon which it rolls. When the output disk is adjusted to a position equal to its own radius, the resulting drive ratio is 1:1. The drive ratio can be set to infinity (i.e. a stationary output disk) by moving

15147-399: The effective diameter of the pulley is dependent on the distance between the two halves of the pulley. The V-shaped cross-section of the belt causes it to ride higher on one pulley and lower on the other; therefore, the gear ratio is adjusted by moving the two sheaves of one pulley closer together and the two sheaves of the other pulley farther apart. As the distance between the pulleys and

15300-541: The electrically driven wheels during cruise. This allows a simpler approach to power-management. This layout also has the advantage of providing four-wheel-drive in some conditions. (An example of this principle is a bicycle fitted with a front hub motor, which assists the cyclist's pedal power at the rear wheel.) Vehicles of this type include the Audi 100 Duo II and Subaru VIZIV concept cars, Peugeot 3008 , Peugeot 508 , 508 RXH , Citroën DS5 (all using PSA 's HYbrid4 system),

15453-629: The electronic accessories. General Motors then introduced their BAS Hybrid system, another mild-hybrid implementation officially released on the 2007 Saturn Vue Green Line . Its "start-stop" functionality operates similarly to the Silverado, although via a belted connection to the motor/generator unit. However the GM BAS Hybrid System can also provide modest assist under acceleration and during steady driving, and captures energy during regenerative (blended) braking. BAS Hybrid offered as much as

15606-448: The elements form a conical surface. In the stack of bands, each band corresponds to a slightly different drive ratio, and thus the bands slide over each other and need sufficient lubrication . An additional film of lubricant is applied to the pulleys. The film needs to be thick enough to prevent direct contact between the pulley and the chain, but thin enough to not waste power as each chain element enters it. Some CVTs transfer power to

15759-417: The engine and the engine controls: both the gas pedal/accelerator and the gearshift lever in an HSD car merely send electrical signals to a control computer . HSD is a refinement of the original Toyota Hybrid System ( THS ) used in the 1997 to 2003 Toyota Prius. The second generation system first appeared on the redesigned Prius in 2004. The name was changed in anticipation of its use in vehicles outside

15912-564: The engine and wheels is discarded. The engine instead acts as an electric generator, attached to the battery via cable. The linkage is engine to battery to electric motor to wheels. In some cases, the generator also directly links to the motor. This serial arrangement is common in diesel–electric locomotives and ships (the Russian river ship Vandal , launched in 1903, was the world's first diesel-powered and diesel–electric powered vessel). Ferdinand Porsche successfully used this arrangement in

16065-512: The engine can be operated at or near its ideal speed and torque level for power, economy, or emissions, with the battery pack absorbing or supplying power as appropriate to balance the demand placed by the driver . During traffic stops the internal combustion engine can even be turned off for even more economy. The combination of efficient car design, regenerative braking, turning the engine off for traffic stops, significant electrical energy storage and efficient internal combustion engine design give

16218-579: The engine to operate at a constant angular velocity 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. 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

16371-461: The favorable region of the brake specific fuel consumption map, significantly contributes to the higher overall efficiency of the vehicle. Interesting variations of the simple design (pictured at right) found, for example, in the well-known Toyota Prius are the: The Toyota Hybrid System THS / Hybrid Synergy Drive has a single power-split device (incorporated as a single three-shaft planetary gearset) and can be classified as an Input-Split, since

16524-429: The first ever flight of a series hybrid powertrain. Diamond Aircraft state that the technology is scalable to a 100-seat aircraft. If the motors are attached to the vehicle body, flexible couplings are required but not if the traction motors are integrated into the wheels . One disadvantage is that the unsprung mass increases and suspension responsiveness decreases, which impacts ride and potentially safety. However

16677-423: The first such vehicles to be fitted with a hydrostatic CVT. The design used a variable-displacement swash-plate pump and fixed-displacement gear-type hydraulic motor combined into a single compact package. Reverse ratios were achieved by reversing the flow of the pump through over-centering of the swashplate. Acceleration was limited and smoothed through the use of pressure accumulator and relief valves located between

16830-480: The flywheel is sufficient that the kinetic energy is converted into electricity, intermittently, at the speed required by the generator. Some drill presses and milling machines contain a simple belt-drive CVT system to control the speed of the chuck , including the Jet models J-A5816 and J-A5818. In this system, the effective diameter of only the output shaft pulleys is continuously variable. The input pulley connected to

16983-493: The forward-reverse shuttle times are reduced. The speed and power output of the CVT is used to control the travel speed and sometimes steering of the equipment. In the latter case, the required speed differential to steer the equipment can be supplied by independent CVTs, allowing the steering to be accomplished without several drawbacks associated with other skid steer methods (such as braking losses or loss of tractive effort). The 1965 Wheel Horse 875 and 1075 garden tractors were

17136-513: The front inverter. "E-Four" began being offered in Prius models in the United States in the 2019 model year. "E-Four" is an integral part of the RAV4 Hybrid models offered in the United States, and all such RAV4 Hybrids are "E-Four" only. The L310 transmission for rear-wheel drive applications succeeded the prior L110 transmission in premium vehicles. Compared to the L110 and L210, the L310 couples MG2 to

17289-686: The impact should be minimal as electric motors in wheel hubs such as Hi-Pa Drive , may be very small and light having exceptionally high power-to-weight ratios and braking mechanisms can be lighter as the wheel motors brake the vehicle. Advantages of individual wheel motors include simplified traction control , all wheel drive if required and a lower floor (useful for buses and other specialised vehicles (some 8x8 all-wheel drive military vehicles use individual wheel motors). Diesel–electric locomotives have used this concept (individual motors driving axles of each pair of wheels) for 70 years. Other measures include lightweight aluminium wheels to reduce

17442-408: The injection and ignition of fuel to turn over the engine. Continuously variable transmission A continuously variable transmission ( CVT ) is an automated transmission that can change 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

17595-573: The integrated electrical generator, used in the Nissan concept Infiniti Emerg-e . This operating profile allows greater scope for alternative engine designs, such as a microturbine , rotary Atkinson cycle engine or linear combustion engine . The ICE is matched to the electric engine by comparing the output rates at cruising speed . Generally, output rates for combustion engines are provided for instantaneous (peak) output rates, but in practice these can't be used. The use of an electric motor driving

17748-483: The internal combustion engine with the sun gear and couples the starter/generator (MG1) with the planetary gear carrier, which is the opposite of the G1 THS scheme. In addition, the single-motor G1 THS omits the traction motor (MG2) and uses a belt-drive continuously variable transmission which can be selectively coupled via rotating clutches to either the planetary gear carrier or the ring gear. An all-wheel drive option for

17901-530: The job of larger motors when compared to single-mode systems, because the derived electrical peak power is proportional to the width of the continuous variation range. The four fixed gears enable the Two-Mode Hybrid to function like a conventional parallel hybrid under high continuous power regions such as sustained high speed cruising or trailer towing. Full electric boost is available in fixed-gear modes. These contain two different energy recovery systems. This

18054-610: The larger units. In mowing or harvesting operations, the CVT allows the forward speed of the equipment to be adjusted independently of the engine speed; this allows the operator to slow or accelerate as needed to accommodate variations in the thickness of the crop. Hydrostatic CVTs are used in small- to medium-sized agricultural and earthmoving equipment. Since the engines in these machines are typically run at constant power output (to provide hydraulic power or to power machinery), losses in mechanical efficiency are offset by enhanced operational efficiency. For example, in earthmoving equipment,

18207-467: The length of the belt does not change, both pulleys must be adjusted (one bigger, the other smaller) simultaneously to maintain the proper amount of tension on the belt. Simple CVTs combining a centrifugal drive pulley with a spring-loaded driven pulley often use belt tension to effect the conforming adjustments in the driven pulley. The V-belt needs to be very stiff in the pulley's axial direction to make only short radial movements while sliding in and out of

18360-501: The maximum speed is significantly lower than other pulley-based CVTs. The sliding plates will slowly wear over years of usage. Therefore the plates are made longer than is needed, allowing for more wear before the chain must be refurbished or replaced. Constant lubrication is required and so the housing is usually partially filled with oil. Toroidal CVTs, as used on the Nissan Cedric (Y34) , and those built by CVTCORP, consist of

18513-498: The mechanical transmission rather than being a supplementary source of motive power. One of the earliest forms of hybrid land vehicle was the 'trackless' trolleybus experiment in The United States (New Jersey) that ran from 1935 to 1948, which normally used traction current delivered by wire. The trolleybus was fitted with an internal combustion engine to power the mechanical drivetrain directly, not to generate electricity for

18666-408: The motor to turn more rapidly. Another method is to employ a variable displacement pump .  When the pump is configured for low displacement, it produces a low volume of oil flow, causing the hydraulic motor(s) to turn more slowly.  As the pump's displacement is increased, a greater volume of oil flow is produced for any given engine RPM, causing the motor(s) to turn faster. Advantages of

18819-399: The outermost radius. As the chain moves into the pulleys the contact area gets smaller. As the contact area is proportional to the number of elements, chain belts require many very small elements. A belt-driven design offers approximately 88% efficiency, which, while lower than that of a manual transmission , can be offset by enabling the engine to run at its most efficient RPM regardless of

18972-459: The output disk to the center of the input disk. The output direction can also be reversed by moving the output disk past the center of the input disk. The transmission on early Plymouth locomotives worked this way, while on tractors using friction disks, the range of reverse speeds was typically limited. Still in development, the magnetic CVT transmits torque using a non-contact magnetic coupling. The design uses two rings of permanent magnets with

19125-509: The output pulley via tension in the belt (a "pulling" force), while others use compression of the chain elements (where the input pulley "pushes" the belt, which in turn pushes the output pulley). Positively Infinitely Variable (PIV) chain drives are distinct in that the chain positively interlocks with the conical pulleys. This is achieved by having a stack of many small rectangular plates in each chain link that can slide independently from side-to-side. The plates may be quite thin, around

19278-486: The output shaft can freely rotate, like an automotive transmission in neutral) due to providing high back-driving torque. Other IVTs, such as ratcheting types, allow the output shaft to freely rotate. The types of CVTs which are able to function as IVTs include epicyclic, friction-disk, and ratcheting CVTs. In 1879, Milton Reeves invented a CVT (then called a variable-speed transmission ) for use in sawmilling. In 1896, Reeves began fitting this transmission to his cars, and

19431-601: The physical size of the traction motor (MG2) in THS-II remains approximately the same, but the maximum output has increased from 33 to 50 kW (44 to 67 hp) and the maximum torque has increased from 350 to 400 N⋅m (260 to 300 lbf⋅ft). The stator windings are connected in series, which requires a higher potential. Although not part of the THS/HSD as such, starting with the 2004 Prius, all THS/HSD vehicles have been fitted with an electric air-conditioning compressor, instead of

19584-695: The planetary gear carrier. On October 13, 2015, Toyota announced details of the Fourth Generation Hybrid Synergy Drive which was introduced for the 2016 model year. The overall design returns to a single planetary gearset similar to THS/THS-II; parallel reduction gears on the Fourth Generation transaxles replace the Motor Speed Reduction Device, which is a second planetary gear set found in the Third Generation transaxles. The transaxle and traction motor have been redesigned, delivering

19737-535: The power and the second providing electricity. Either source may provide the primary motive force, with the other augmenting the primary. Other combinations offer efficiency gains from superior energy management and regeneration that are offset by cost, complexity and battery limitations. Combustion-electric (CE) hybrids have battery packs with far larger capacity than a combustion-only vehicle. A combustion-electric hybrid has batteries that are light that offer higher energy density and are far more costly. ICEs require only

19890-537: The power of the engine is split at the input to the transmission. This in turn makes this setup very simple in mechanical terms, but has drawbacks of its own. For example, in Generation 1 and Generation 2 HSDs maximum speed is mainly limited by the speed of the smaller electric motor (often functioning as a generator). The Generation 3 HSD separates the ICE-MG1 path from the MG2 path, each with its own, tailored gear ratio (1.1:1 and 2.5:1, respectively, for late Priuses, including

20043-417: The power supplied by the primary source from the power demanded by the driver. ICE torque output is minimal at lower RPMs and conventional vehicles increase engine size to meet market requirements for acceptable initial acceleration. The larger engine has more power than needed for cruising. Electric motors produce full torque at standstill and are well-suited to complement ICE torque deficiency at low RPMs. In

20196-581: The power transfer is fully hydrostatic).  This arrangement reduces the load on the hydrostatic portion of the transmission when in the forward direction by transmitting a significant portion of the torque through more efficient fixed gears. A variant called the Integrated Hydrostatic Transaxle (IHT) uses a single housing for both hydraulic elements and gear-reducing elements and is used in some mini-tractors and ride-on lawn mowers . The 2008–2010 Honda DN-01 cruiser motorcycle used

20349-399: The pulleys. The radial thickness of the belt is a compromise between the maximum gear ratio and torque. Steel-reinforced V-belts are sufficient for low-mass, low-torque applications like utility vehicles and snowmobiles, but higher-mass and -torque applications such as automobiles require a chain. Each element of the chain must have conical sides that fit the pulley when the belt is running on

20502-461: The pump and motor, to prevent the sudden changes in speed possible with direct hydraulic coupling. Subsequent versions included fixed swash plate motors and ball pumps. The 1996 Fendt Vario 926 was the first heavy-duty tractor to be equipped with a IVT transmission. It is not the same thing as a hydrostatic CVT. Over 100,000 tractors have been produced with this transmission. CVTs have been used in aircraft electrical power generation systems since

20655-412: The pump's output back to the reservoir through an adjustable valve.  With such an arrangement, as more oil is diverted by opening the valve, the effective displacement of the pump is reduced and less oil is delivered to the motor, causing it to turn more slowly.  Conversely, closing the valve will reduce the volume of oil being diverted, increasing the effective displacement of the pump and causing

20808-399: The ring gear of the PSD. In addition L310 adds a third planetary gearset, compounded with the second (MSRD) by coupling the planetary gear carrier of the second planetary gearset with the ring gear of the third planetary gearset, and by coupling the ring gear of the second with the planetary gear carrier of the third. In addition, several rotating clutches and brakes have been added, including

20961-597: The rollers determines the transmission ratio. In an epicyclic CVT (also called a planetary CVT), the gear ratio is shifted by tilting the axes of spherical rollers to provide different contact radii, which in turn drive input and output discs. This is similar in principle to toroidal CVTs. Production versions include the NuVinci CVT . Several hybrid electric vehicles —such as the Toyota Prius, Nissan Altima, Mitsubishi Outlander PHEV, and Ford Escape Hybrid —use electric variable transmissions (EVTs, sometimes eCVT) to control

21114-400: The rotation speeds of the engine and MG1, with MG1 used to absorb the difference between wheel and engine speed. The differential is an epicyclic gear set (also called a "power split device"); that and the two motor-generators are all contained in a single transaxle housing that is bolted to the engine . Special couplings and sensors monitor rotation speed of each shaft and the total torque on

21267-411: The same design as THS, combining traction power from an internal combustion engine and an electric motor via a planetary gearset (power split device) which can divert some power to an electrical generator. Electrically, HSD/THS-II adds a DC to DC converter boosting the potential of the battery to 500 V or more. This allows smaller battery packs to be used, and more powerful motors. Compared to THS,

21420-410: The second generation Prius consisted of 28 Panasonic prismatic nickel metal hydride modules, each containing six 1.2 volt cells, connected in series to produce a nominal voltage of 201.6 volts. The discharge power capability of the second gen Prius pack is about 20 kW at 50% state of charge (SoC). The power capability increases with higher temperatures and decreases at lower temperatures. The Prius has

21573-405: The system allows the mechanical power from the ICE to be split three ways: extra torque at the wheels (under constant rotation speed), extra rotation speed at the wheels (under constant torque), and power for an electric generator. A computer running appropriate programs controls the systems and directs the power flow from the different engine + motor sources. This power split achieves the benefits of

21726-439: The top speed of the vehicle; if there is more demand, the battery can be completely exhausted, so that this extra torque boost is not available. Then the system reverts to just the power available from the engine. This results in a large decline in performance under certain conditions: an early-model Prius can achieve over 90 mph (140 km/h) on a 6 degree upward slope, but after about 2,000 feet (610 m) of altitude climb

21879-491: The traction battery has enough charge. This permits all-electric driving with no fuel consumption for up to 1 mi (1.6 km). However, the HSD software switches to EV mode automatically whenever it can. Only the Toyota Prius Plug-in Hybrid has a longer driving all-electric range in blended operation electric-gasoline of 11 mi (18 km) ( EPA rating) until the battery is depleted. The Prius PHEV

22032-529: The traction battery, and a 12 volt lead-acid battery known as the Low Voltage (LV) battery, which functions as an auxiliary battery. The LV battery supplies power to the electronics and accessories when the hybrid system is turned off and the high-voltage battery main relay is off. The traction battery is a sealed nickel-metal hydride (NiMH) battery pack. The battery pack of the first generation Toyota Prius consisted of 228 cells packaged in 38 modules, while

22185-419: The traction motor. This enabled the vehicle to be used for revenue service where there was no contact wire. Since the 1990s trolleybus hybrids have been introduced with small power plants to provide a low speed capability for emergency and maintenance but not to support general revenue service. Parallel hybrid systems have both an internal combustion engine and an electric motor that can both individually drive

22338-408: The transmission type for standards specification lists or regulatory purposes. In a conventional car design the separately-excited alternator with integral rectifier (DC generator) and starter (DC motor) are considered accessories that are attached to the internal combustion engine (ICE) which normally drives a transmission to power the wheels propelling the vehicle. A battery is used only to start

22491-402: The truck is coasting, braking, or stopped, yet restart quickly to provide power. Accessories can continue to run on electrical power while the engine is off, and as in other hybrid designs, regenerative braking recaptures energy. The large electric motor spins up the engine to operating-speeds before injecting fuel. The 2004–2007 Chevrolet Silverado PHT was a full-size pickup truck . Chevrolet

22644-399: The two sources may be applied to the same shaft (for example with the electric motor connected between the engine and transmission), turning at equal speeds and the torques adding up with the electric motor adding or subtracting torque to the system as necessary. (The first two generations of Honda Insight use this system.) Parallel hybrids can be further categorized by the balance between

22797-450: The vehicle's speed. When power is more important than economy, the ratio of the CVT can be changed to allow the engine to turn at the RPM at which it produces the greatest power. In a chain-based CVT, numerous chain elements are arranged along multiple steel bands layered over one another, each of which is thin enough to easily bend . When part of the belt is wrapped around a pulley, the sides of

22950-403: The wheels between a ratio of 3.9 and 1.9, for low and high speed driving regimes respectively. This decreases the power flowing from MG1 to MG2 (or vice versa) during higher speeds. The electrical path is only about 70% efficient, thus decreasing its power flow while increasing the overall performance of the transmission. The second planetary gearset is extended with a second carrier and sun gear to

23103-399: Was able to get a 10% efficiency improvement by shutting down and restarting the engine on demand and using regenerative braking. The electrical energy was used only to drive accessories such as power steering. The GM PHT used a 42 volt system via three 12 volt vented lead acid batteries connected in series (36V total) to supply the power needed for the startup motor, as well as to power

23256-488: Was called the Toyota Hybrid System (THS) when it was introduced with the Prius in 1997. The hybrid transaxle , designated P110, includes two electric motors (MG1 and MG2) and a planetary gearset , which Toyota calls the "Power Split Device" (PSD); mechanical power from the internal combustion engine (E) can be directed either to the wheels or to MG1, acting as a generator. Electrical power flows between MG1, MG2, and

23409-461: Was patented in 2014. A hydrostatic CVT uses an engine-driven, positive-displacement pump to deliver oil under pressure to one or more hydraulic motors , the latter creating the torque that is applied to the vehicle's driving wheel(s).  The name "hydrostatic CVT," which misuses the term " hydrostatic ," differentiates this type of transmission from one that incorporates a hydrodynamic torque multiplier ("torque converter") into its design. In

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