Global Hybrid Cooperation, formerly Advanced Hybrid System 2 (AHS2), is a set of hybrid vehicle technologies jointly developed by General Motors, Daimler, and Chrysler LLC, with BMW joining in 2005. It uses 2 or 3 planetary gearsets in an automatic transmission: one on the internal combustion engine (ICE) side (input split) paired with a second (output split), forming the compound split, and possibly one third additional planetary gearset to multiply the number of fixed gear ratios (up to 4). General Motors has stopped using the "AHS2" name as of 2006, preferring to call it simply a two-mode hybrid system.
This technology was named as "Technology of the Year" for 2007 by Automobile magazine. [1]
The dual-mode hybrid concept, as described in 1994, was developed to optimize vehicle efficiency by switching between parallel and series hybrid operation, taking advantage of series operation in stop-and-go traffic to minimize engine speed variance, and parallel operation at highway speeds to use efficient mechanical transmission. [2] : 4 On September 30, 1993, the United States Department of Energy signed a contract with General Motors to develop and demonstrate hybrid electric powertrains for light duty vehicles. [3] : 22 AHS-2 was derived from a dual-mode hybrid system developed earlier by Allison Transmission, then a division of GM, for transit buses. The Allison system first had been announced for buses in 2003. [4]
The GM/DaimlerChrysler partnership was announced on December 13, 2004, with Dieter Zetsche of DaimlerChrysler joining Rick Wagoner of GM on stage with a prototype. [5] Negotiations had begun earlier in October, after engineering managers at both companies discovered they were independently working on similar dual-mode hybrid concepts while participating on the same conference panel. [6] The agreement was not signed until the following August, however. [7] GM was reportedly responsible for development of rear- and four-wheel drive truck and front wheel drive car systems while DaimlerChrysler was focused on a rear wheel drive luxury car application. [7] It was announced on September 7, 2005, that BMW would also join the alliance, likely using then-archrival DaimlerChrysler's rear wheel drive system. [7]
The three companies formed an organization called Global Hybrid Cooperation with engineering and management centered at the GM, DaimlerChrysler and BMW Hybrid Development Center in Troy, Michigan. [7] In 2006, an article published by Autoweek stated the three automakers planned to spend US$1 billion collectively to develop the front- and rear-wheel drive hybrid transmissions. [8]
The two-mode hybrid system was introduced to the light-duty vehicle market as a drivetrain option for the 2008 model year Chevrolet Tahoe and GMC Yukon, [9] with an observed improvement in fuel economy of 27–58% compared to a conventionally-powered equivalent. [10] GM introduced the hybrid option for 2009 model year Chevrolet Silverado, [11] GMC Sierra, and Cadillac Escalade. The largest improvement was in the EPA city rating. [12] The dual-mode hybrid equipment added approximately 350 lb (160 kg), but this increase was offset completely by lighter seats, wheels, and 12-volt battery; aluminum engine and body components; and eliminating the starter motor. [10] It was equipped with a 6.0L LFA and LZ1 V-8 engines featuring Active Fuel Management, which was larger than the standard 5.3L LY5 base engine. [10]
The GM products were followed by a hybrid Dodge Durango and related Chrysler Aspen for the 2009 model year in late 2008; the 5.7L HEMI V-8 engine on these was equipped with a stop-start system to improve fuel economy. [13] [14] BMW and Mercedes introduced the X6 ActiveHybrid and ML450 Hybrid, respectively, in 2009, [15] [16] but these were discontinued in 2011. [17]
Earlier, on March 1, 2007, BMW and DaimlerChrysler announced that they were entering a separate partnership to develop a mild hybrid module for rear wheel drive premium cars. [18] [19] They planned to roll out the new system within the next three years on BMW and Mercedes-Benz vehicles. GM did not participate in the new partnership, and did not announce plans to develop a similar hybrid RWD system for cars. [20]
In 2009 Mercedes released the S400 mild hybrid, using a lithium ion battery. [21] It was reported in July 2009 that after the upcoming introductions of two-mode hybrid models of the BMW X6 (marketed globally) and the Mercedes-Benz M class (only in the United States), the two-mode hybrid joint venture would be dissolved. Daimler indicated that it wants to avoid investing in aftersales and service for a vehicle which will only be produced in small quantities, and will instead concentrate on modular hybrid building blocks with scalable lithium-ion batteries, based on the hybrid drive developed for the S-class and 7 Series sedans by the joint venture with BMW and auto supplier Continental AG. [22]
By 2014, the two-mode hybrid drivetrain was no longer offered on any light-duty vehicles. [9]
The dual-mode hybrid drive unit includes two AC motor-generators (MG-A and MG-B, each are three-phase permanent magnet machines with 82 kW (110 hp) peak output), [24] three planetary gear sets (P1, P2, and P3), four selectively engaging friction clutches (C1, C2, C3, and C4), and two oil pumps. [1]
This hybrid drive unit is coupled to the engine, taking the place of a conventional transmission. The entire drive unit is comparable in size and shape to an Allison 1000 automatic transmission. A 300 volt battery pack is housed elsewhere in the vehicle to store energy for the two motor-generators.
General Motors has designated the drive unit as the 2ML70; [25] for BMW and DaimlerChrysler vehicles, it is the GM-Allison AHS-2. [26] The technology is known as a "two-mode" hybrid system because the transmission / drive unit can transfer either electrical power, mechanical power, or a blend of both to the wheels, operating both as a series hybrid, using the internal combustion engine solely to generate electrical power, or as a parallel hybrid, using the electrical motor(s) to augment the mechanical power from the engine. [27] The two modes of operation are:
This system amplifies the output of the electric motors similarly to the way in which a conventional transmission amplifies the torque of an internal combustion engine. It also, when required, permits transfer of more of the engine's torque to the wheels, making the transmission more efficient even without the electric motors in use. Although the transmission mechanically has only four conventional gear ratios, the electric motors allow it to function as a continuously variable transmission. This variable ratio functions in addition to the torque multiplication of the planetary gears.
Operation of the Allison Transmission (AHS-2), or Two-Mode Hybrid, from the Global Hybrid Cooperation. This transmission is mounted on the BMW X6 ActiveHybrid and the Mercedes-Benz ML450 BlueHybrid. [29]
Per the patent, the planetary gearsets P1 and P2 are compounded, with MG-A driving (or being driven by) the sun gear of P1, which is coupled to the ring gear of P2, and the carriers for the planet gears in P1 and P2 are coupled. [23] : col.6 ll.24–33 Similarly, MG-B drives (or is driven by) the sun gear of P2, which is coupled to the sun gear of P3 via a hollow shaft. [23] : col.6 ll.54–64
Name (aka) | Schematic | Clutch engagement | MG operation | Description | |||||
---|---|---|---|---|---|---|---|---|---|
C1 | C2 | C3 | C4 | MG-A | MG-B | ||||
Mode I: First Power Split Mode (Input-Split) | Yes | No | No | No | Gen | Mot | Generally, the vehicle will launch in Mode I; as speeds increase, the transmission will transition to the first fixed gear ratio, shift back to Mode I, then transition to the second fixed gear ratio before entering Mode II. [23] : col.11 ll.53–56 Throughout Mode I, clutch C1 remains engaged. This locks the ring gear of planetary gearset P3, which in turn forces the rotational speed of the second motor-generator (MG-B, connected to the sun gear of P3) to be proportional to the output driveshaft (planetary gears of P3). [23] : col.10 ll.5–14 The first planetary gearset pair acts as a four-driveshaft power-split transmission, and the last planetary gearset reduces the rotational speed. [23] : col.9 ll.61–67 MG-A acts as a generator, [23] : col.10 ll.29–30 while MG-B acts as a motor. [23] : col.10 ll.5–6 | ||
within Mode I | First Fixed Gear ratio | No | No | Yes | Sync'd | In general, when maximum power is required at low speeds, C4 is engaged in addition to C1, entering the first fixed gear ratio. [23] : col.11 ll.26–34 By engaging shunt clutch C4, the first two planetary gearsets (P1, P2) are maintained in a synchronous 1:1 fixed gear ratio, and the last planetary gearset (P3) reduces the rotational speed. [23] : col.11 ll.5–10 With C4 engaged, both motor-generators are mutually synchronous, and both can be operated either as motors for maximum acceleration, or as generators for regenerative braking. [23] : col.10 ll.10–17 It's the midpoint of the first continuously variable range, when both motor-generators rotational speed join. | |||
Second Fixed Gear ratio | Yes | No | No | Off / freewheel | At higher speeds within Mode I, C2 is engaged alongside C1 to enter the second fixed gear ratio. [23] : col.11 ll.41–43 All three planetary gearsets (P1, P2, P3) are active, collectively forming an intermediate fixed gear ratio, and both motor-generators can be turned off, with the vehicle motivated solely by mechanical power transmitted from the engine. [23] : col.11 ll.43–49 The rotational speed of both motor-generators are very asymmetric (1:9), excluding effective usage of the first one (MG-A). It's the boundary between both continuously variable ranges. The two-modes switching occurs at this point, when the third planetary gearset ring gear reach zero rotational speed, and all the planetary gearset carriers gears reach the same rotational speed together. | ||||
Mode II: Second Power Split Mode (Compound-Split) | No | Yes | No | No | Mot | Gen | The vehicle enters Mode II from the second fixed gear in Mode I by disengaging clutch C1. Again, the first planetary gearset pair acts as a four-driveshaft power-split transmission. Neither of the two motor-generators is directly coupled with input or output. MG-A briefly operates as a generator in Mode II when the vehicle is traveling at speeds in the lower range of Mode II, transitioning to operation as a motor at higher speeds. [23] : col.12 ll.17–34 At the same transition point, MG-B switches from a motor to a generator. [23] : col.12 ll.35–40 | ||
within Mode II | Third Fixed Gear ratio | No | No | Yes | Sync'd | The first planetary gearset pair are in a synchronous 1:1 fixed gear ratio by C4 clutch action, and, by the way, both motor-generators are mutually synchronous, either all as motor, or all as generator. It's the midpoint of the second continuously variable range, when both motor-generators rotational speed join. | |||
Fourth Fixed Gear ratio | No | Yes | No | Off / freewheel | The third C3 clutch block the first planetary gearset sun gear, and the second motor-generator (MG-B) still off-line. |
Toyota's Hybrid Synergy Drive may appear similar in that it also combines the power from an ICE and a pair of electric motor–generators; however in its current form, Toyota uses only one planetary gearset providing only single mode functionality (i.e. input split only) using a series/parallel architecture. [30]
Honda's Integrated Motor Assist uses a traditional ICE and transmission where the flywheel is replaced with an electric motor: it is a simple parallel architecture, [30] requiring the addition of a mechanical continuously variable transmission (CVT), i.e. not electrically variable.
The two-mode hybrid drive system manufactured by Allison Transmission was first used in New Flyer transit buses which entered revenue service in 2004; [31] in testing at the National Renewable Energy Laboratory, measured fuel economy improved by 0.69–1.09 mpg‑US (341–216 L/100 km; 0.83–1.31 mpg‑imp), representing an improvement of 30.3 – 74.7% compared to a conventional diesel-powered bus. [32] : 10
By 2008, Allison had delivered 1,000 hybrid powertrains. [33] Many transit operators since then have received buses with the Allison hybrid system, now branded eGen Flex, [34] including:
The longitudinal system for light trucks from General Motors will be manufactured at Baltimore Transmission by GM's PowerTrain division. The nickel-metal hydride batteries will be manufactured by Panasonic EV of Japan.
The system was introduced for the 2008 model year in the full-sized Chevrolet Tahoe and GMC Yukon SUVs as a specific 2-Mode Hybrid model. Rear wheel drive and four wheel drive light duty trucks using the 2-mode hybrid system include:
The Mercedes-Benz Group AG is a German multinational automotive corporation headquartered in Stuttgart, Baden-Württemberg, Germany. It is one of the world's leading car manufacturers. Daimler-Benz was formed with the merger of Benz & Cie., the world's oldest car company, and Daimler Motoren Gesellschaft in 1926. The company was renamed DaimlerChrysler upon the acquisition of American automobile manufacturer Chrysler Corporation in 1998, and was again renamed Daimler AG upon divestment of Chrysler in 2007. In 2021, Daimler AG was the second-largest German automaker and the sixth-largest worldwide by production. In February 2022, Daimler was renamed Mercedes-Benz Group as part of a transaction that spun-off its commercial vehicle segment as an independent company, Daimler Truck.
A hybrid vehicle is one that uses two or more distinct types of power, such as submarines that use diesel when surfaced and batteries when submerged. Other means to store energy include pressurized fluid in hydraulic hybrids.
The Mitsubishi Fuso Truck and Bus Corporation is a Japanese manufacturer of trucks and buses. It is headquartered in Kawasaki, Kanagawa and owned by Germany-based Daimler Truck.
An automatic transmission is a multi-speed transmission used in motor vehicles that does not require any input from the driver to change forward gears under normal driving conditions. Vehicles with internal combustion engines, unlike electric vehicles, require the engine to operate in a narrow range of rates of rotation, requiring a gearbox, operated manually or automatically, to drive the wheels over a wide range of speeds.
A four-wheel drive, also called 4×4 or 4WD, is a two-axled vehicle drivetrain capable of providing torque to all of its wheels simultaneously. It may be full-time or on-demand, and is typically linked via a transfer case providing an additional output drive shaft and, in many instances, additional gear ranges.
A diesel–electric transmission, or diesel–electric powertrain, is a transmission system for vehicles powered by diesel engines in road, rail, and marine transport. Diesel–electric transmission is based on petrol–electric transmission, a transmission system used for petrol engines.
The Mercedes-Benz GLE, formerly Mercedes-Benz M-Class, is a mid-size luxury SUV produced by the German manufacturer Mercedes-Benz since 1997. In terms of size, it is slotted in between the smaller GLC and the larger GLS, the latter with which it shares platforms.
The BMW E70 is the second-generation BMW X5 mid-size luxury SUV. It replaced the BMW X5 (E53) in July 2006. It was manufactured alongside the BMW X6 at BMW's Greer, South Carolina plant in the U.S. and BMW's facility in Toluca, Mexico.
Hybrid Synergy Drive (HSD), also known as Toyota Hybrid System II, is the brand name of Toyota Motor Corporation for the hybrid car drive train technology used in vehicles with the Toyota and Lexus marques. First introduced on the Prius, the technology is an option on several other Toyota and Lexus vehicles and has been adapted for the electric drive system of the hydrogen-powered Mirai, and for a plug-in hybrid version of the Prius. Previously, Toyota also licensed its HSD technology to Nissan for use in its Nissan Altima Hybrid. Its parts supplier Aisin Seiki Co. offers similar hybrid transmissions to other car companies.
Integrated Motor Assist is Honda's hybrid car technology, introduced in 1999 on the Insight. It is a specific implementation of a parallel hybrid. It uses an electric motor mounted between the internal combustion engine and transmission to act as a starter motor, engine balancer, and assist traction motor.
Power steering is a system for reducing a driver's effort to turn a steering wheel of a motor vehicle, by using a power source to assist steering.
Allison Transmission is an American manufacturer of commercial duty automatic transmissions and hybrid propulsion systems. Allison products are specified by over 250 vehicle manufacturers and are used in many market sectors, including bus, refuse, fire, construction, distribution, military, and specialty applications.
The Dodge Intrepid ESX prototype cars are the result of the 1993 response by the Chrysler Corporation to a challenge by U.S. President Bill Clinton to produce a vehicle which was capable of meeting the demands of the modern consumer, while still achieving an unprecedented 80 miles per US gallon overall in fuel economy. The PNGV - Partnership for a New Generation of Vehicles project was aimed at The Big Three American car manufacturers.
The Mitsubishi Fuso Aero Star (kana:三菱ふそう・エアロスター) is a heavy-duty single-decker bus produced by the Japanese manufacturer Mitsubishi Fuso. The range was available as either a public bus or a coach. Its principal competitors are the Isuzu Erga, the Nissan Diesel Space Runner RA and the Hino Blue Ribbon.
Hybrid vehicle drivetrains transmit power to the driving wheels for hybrid vehicles. A hybrid vehicle has multiple forms of motive power.
The BMW X6 is a mid-size luxury crossover SUV by German automaker BMW. The BMW X6 is the originator of the sports activity coupé (SAC), referencing its sloping rear roof design. It combines the attributes of an SUV with the stance of a coupé. It is built in BMW's North American plant in Greer, South Carolina alongside the BMW X5, whose platform it shares. Prior to the release of the X7, the X6 was considered a flagship SUV for BMW.
The Orion VII is a line of low-floor transit buses available in 30' rigid, 35' rigid, and 40' rigid lengths manufactured by Daimler Buses North America's subsidiary Orion Bus Industries between 2001 and 2013 in three generations. The conventional powered buses, either with longitudinally-mounted diesel or natural gas engines, used a T-drive transmission coupling. A series hybrid variant powered by a diesel-driven generator was also available. The Orion VII replaced the fully low-floor Orion VI and high-floor Orion V buses, and was manufactured until its parent company DaimlerChrysler withdrew from the transit bus market in 2013.
A range extender is a fuel-based auxiliary power unit (APU) that extends the range of a battery electric vehicle by driving an electric generator that charges the vehicle's battery. This arrangement is known as a series hybrid drivetrain. The most commonly used range extenders are internal combustion engines, but fuel-cells or other engine types can be used.
{{cite journal}}
: CS1 maint: multiple names: authors list (link){{cite journal}}
: CS1 maint: multiple names: authors list (link)