MT (manual transmission) uses simple spur gears providing excellent transmission efficiency and thus typically get 10% or better fuel mileage than current ATs (automated transmissions). The object of the ATM (automated manual transmission ) is to automate starting and gear shifting while retaining this excellent fuel efficiency. A round of fierce competition was triggered among European manufacturers to see who would be the first to develop what is generally known as a conventional AMT that attempts to automate the shifting of MT. The problem with this design is that the drive torque is momentarily interrupted during shifting. This results in a very different shift feeling from an AT, and thus never saw the wide spread acceptance as a replacement for the conventional AT in mainstream vehicles. This was more recently followed by a twin clutch AMT that is receiving great deal of attention. Supporting smooth and responsive shifting much like an AT, the twin-clutch AMT has been installed by European vehicle manufacturer on some high engine capacity sport cars beginning last fall. Hitachi group has now developed an original torque-assist AMT that is fundamentally different from these other two approaches.
TORQUE-ASSIST AMT
In order to achieve widespread acceptance as a replacement for conventional transmissions, the next generation must provide the good fuel economy of an MT, the effortless shifting of an AT, and must also be compact and affordable. Unfortunately, the conventional AMT fails to achieve the seamless shifting of an AT and the twin clutch AMT is difficult to implement compactly and cost effectively.
Hitachi Group has proposed a third way that does meet all the above requirements a torque assist AMT and is now in the process of developing this system. A key advantage of this approach is that it can be implemented with relatively little modification to existing AMTs by simple adding a friction clutch called as assist clutch to the transmission. Action of the assist clutch effectively solves the torque interruption problem of the conventional AMT while providing the smooth gear shifting of an AT. A compact and economical torque assist AMT could thus be implemented fairly easily for application on mainstream FF (front-engine front-drive) compact vehicles with engine displacement with 2 liters.
TORQUE-ASSIST AMT
In order to achieve widespread acceptance as a replacement for conventional transmissions, the next generation must provide the good fuel economy of an MT, the effortless shifting of an AT, and must also be compact and affordable. Unfortunately, the conventional AMT fails to achieve the seamless shifting of an AT and the twin clutch AMT is difficult to implement compactly and cost effectively.
Hitachi Group has proposed a third way that does meet all the above requirements a torque assist AMT and is now in the process of developing this system. A key advantage of this approach is that it can be implemented with relatively little modification to existing AMTs by simple adding a friction clutch called as assist clutch to the transmission. Action of the assist clutch effectively solves the torque interruption problem of the conventional AMT while providing the smooth gear shifting of an AT. A compact and economical torque assist AMT could thus be implemented fairly easily for application on mainstream FF (front-engine front-drive) compact vehicles with engine displacement with 2 liters.
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