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107-417: 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

214-471: 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

321-444: 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

428-419: 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

535-465: 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

642-487: 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,

749-406: 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

856-458: 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

963-556: 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,

1070-438: 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

1177-429: 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

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1284-475: 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

1391-512: 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

1498-641: 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

1605-414: 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

1712-466: 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

1819-669: 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

1926-449: 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

2033-665: 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,

2140-481: 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

2247-414: 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,

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2354-412: 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

2461-414: 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

2568-561: 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

2675-427: 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

2782-561: 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

2889-412: 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

2996-775: 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

3103-409: 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

3210-475: 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

3317-407: 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

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3424-435: 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

3531-409: 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

3638-429: 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

3745-423: 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

3852-480: 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

3959-561: 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

4066-433: 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

4173-467: 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,

4280-525: 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

4387-490: 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

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4494-599: 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

4601-518: 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

4708-554: 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

4815-609: 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

4922-565: 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

5029-486: 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

5136-701: 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

5243-517: 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

5350-483: 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

5457-539: 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

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5564-447: 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)

5671-625: 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

5778-489: 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

5885-430: 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

5992-505: 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

6099-762: 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

6206-472: 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

6313-575: 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

6420-402: 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

6527-488: 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

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6634-457: 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

6741-492: 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

6848-512: 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

6955-678: 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

7062-648: 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

7169-424: 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

7276-437: 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

7383-424: 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

7490-420: 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

7597-428: 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

7704-400: 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

7811-415: 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

7918-550: 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

8025-545: 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),

8132-643: 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

8239-417: 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

8346-569: 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

8453-512: 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

8560-461: 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

8667-429: 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

8774-586: 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

8881-686: 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

8988-577: 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

9095-487: 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

9202-537: 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

9309-506: 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

9416-610: 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

9523-726: 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

9630-535: 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

9737-542: 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

9844-417: 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

9951-399: 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

10058-400: 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

10165-411: 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,

10272-410: 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

10379-405: 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

10486-439: 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

10593-502: 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

10700-535: 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

10807-419: 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

10914-408: 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

11021-402: 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

11128-399: 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

11235-403: 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

11342-399: 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

11449-497: 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

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