Integrated Motor Assist (commonly abbreviated as IMA) is

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technology, introduced in 1999 on the

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. It is a specific implementation of a

parallel hybrid Hybrid vehicle drivetrains transmit power to the driving wheels for hybrid vehicles. A hybrid vehicle has multiple forms of motive power. Hybrids come in many configurations. For example, a hybrid may receive its energy by burning gasoline, but sw ...

. It uses an

electric motor An electric motor is an Electric machine, electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a Electromagneti ...

mounted between the

internal combustion engine An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combus ...

and

transmission Transmission may refer to: Medicine, science and technology * Power transmission ** Electric power transmission ** Propulsion transmission, technology allowing controlled application of power *** Automatic transmission *** Manual transmission *** ...

to act as a

starter motor A starter (also self-starter, cranking motor, or starter motor) is a device used to rotate (crank) an internal-combustion engine so as to initiate the engine's operation under its own power. Starters can be electric motor, electric, pneumatic ...

, engine balancer, and assist

traction motor A traction motor is an electric motor used for propulsion of a vehicle, such as locomotives, electric vehicle, electric or hydrogen vehicles, elevators or electric multiple unit. Traction motors are used in electrically powered rail vehicles (ele ...

Overview

In its first generation, IMA could not power the car on electricity alone, and could only use the motor to assist or start the engine. 2006

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, however, can activate the electric motor while the vehicle is coasting without turning on the internal combustion engine, though in contrast to

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(HSD) or

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and

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, the IMA has a less powerful motor/generator which allows the car to slow or stop its rate of deceleration to a lesser extent; it cannot operate without turning over the engine which is directly coupled to its electric motor.

Regenerative braking

The IMA uses

regenerative braking Regenerative braking is an energy recovery mechanism that slows down a moving vehicle or object by converting its kinetic energy into a form that can be either used immediately or stored until needed. In this mechanism, the electric traction mo ...

to capture some of the energy that would otherwise be lost as heat during braking and reuse that energy later to help accelerate the vehicle. This has three effects: it increases the rate of acceleration, reduces the work required of the

engine An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy. Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power gen ...

, and reduces the frequency of brake hardware replacement. The acceleration boost is important as it allows the engine to be scaled down to a smaller but more fuel-efficient variant without rendering the vehicle unacceptably slow or weak. This smaller engine is the primary reason cars equipped with IMA get better highway mileage than their more conventional counterparts.

Starting

Additionally, vehicles equipped with IMA can shut off their engine when the vehicle stops and use the electric motor to rapidly spin it back up when the driver releases the brake pedal (or in the manual transmission variant, when the shifter is placed into gear from neutral). They also have a conventional starter as a backup, making it the only production hybrid system which can operate with its high voltage electric system disabled, using only its engine like a traditional vehicle. However, since the IMA also acts as the vehicle's

alternator An alternator is an electrical generator that converts mechanical energy to electrical energy in the form of alternating current. For reasons of cost and simplicity, most alternators use a rotating magnetic field with a stationary armature.Go ...

, eventually the 12 volt accessory battery would require an external charge.

Other names

*ISG: Integrated Starter Generator *ISA: Integrated Starter Alternator *ISAD: Integrated Starter Alternator Damper *CAS: Combined Alternator Starter *CSA: Crankshaft Starter Alternator or Combined Starter Alternator *CISG: Crank-mounted Integrated Starter Generator

List of vehicles using IMA

IMA-equipped Honda Civic Hybrid *

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(1997

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) *

Honda Insight The is a hybrid electric vehicle that is manufactured and marketed by Honda. Its first generation was a two-door, two passenger liftback (1999–2006) and in its second generation was a four-door, five passenger liftback (2009–2014). In its ...

(1999-2006, 2010-2014) *

Honda Dualnote The Honda Dualnote (also branded as the Acura DN-X) is a hybrid sports car concept that was initially unveiled at Japan's Tokyo Motor Show in 2001. The Dualnote was powered by a double overhead camshaft (DOHC) i-VTEC V6 motor with Honda's In ...

(2001 concept car) * Honda Fit Hybrid (2010-present) *

Honda Fit Shuttle The Honda Fit Shuttle is a subcompact station wagon derived from the Fit and is mainly available in Japan's domestic market. The Shuttle is also a successor to the station wagon variant of first generation Fit, sold as the Airwave. __TOC__ ...

Hybrid (2010-present) *

Honda Civic Hybrid The is a series of automobiles manufactured by Honda since 1972. Since 2000, the Civic has been categorized as a compact car, while previously it occupied the subcompact class. , the Civic is positioned between the Honda Fit/City and Honda Acc ...

(2003-2015) *

Honda Accord Hybrid The , also known as the in Japan and China for certain generations, is a series of cars manufactured by Honda since 1976, best known for its four-door sedan variant, which has been one of the best-selling cars in the United States since 1989. ...

(2005-2007) *

Honda Freed Hybrid The is a mini MPV produced by the Japanese automaker Honda since 2008. The vehicle is designed mainly for the need of Japanese consumers. It is based on the Fit/Jazz platform and acts as a replacement for the first generation Mobilio in Japan. ...

(2008-present) *

Honda CR-Z The Honda CR-Z is a sport compact hybrid electric automobile manufactured by Honda and marketed as a "sport hybrid coupe." The CR-Z combines a hybrid gasoline-electric powertrain with traditional sports car elements, including a 2+2 seating arran ...

(2010-2016) *

Acura ILX Hybrid The Acura ILX is a subcompact executive car manufactured and marketed by Honda under the Acura brand, based on the ninth-generation Civic sedan. The ILX replaced the Canadian market exclusive Acura CSX. The ILX was Acura's first gasoline-elec ...

(2013-2014)

References

{{reflist

External links

Honda Official "Green Technology - Hybrid"
Automotive technology tradenames Engine technology Honda Hybrid powertrain de: Honda Civic IMA