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Development of New Compact 4-speed Automatic Transmission for Honda LIFE

Article of Honda R&D Technical Review Vol.16 No.2


A new electronically controlled 4-speed automatic transmission has been developed for use in next-generation compact class vehicles and employed in the new Honda LIFE. In addition to new fourth gear shift and lock-up mechanisms, the new AT features a parallel triple-shaft structure with a squashed torque converter and a case with no side cover, and the control system components are also concentrated. These have made the unit more compact, the shortest in its class at 334 mm in overall length. The employment of Active Lock-up II to provide lock-up control has significantly increased the lock-up control area with no loss of drivability. In combination with the addition of a fourth gear and the reduction of friction by 30%, this expansion of the control area has contributed significantly to improved fuel economy.
In addition, the employment of direct control of clutch hydraulic pressure using a linear solenoid, center positioning of idler gear trains on each shaft and climbing and descending control, among a variety of other technologies, has resulted in a smooth and very stable shift feeling, superb quietness and improved drivability.


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(2) Abe, H., Miyoi, N., Yamashita, T., Shirakigawa, K.: Practical Simulation Method by Compensating the Outlet Flow Angle of a Stator, JSAE Annual Congress Proceedings, No. 951, p. 121-124 (1995)
(3) Abe, H., Maruyama, T., et al.: Development of an Ultra Flat Torque Converter by Applying Three-dimensional Computational Fluid Dynamics, Honda R&D Technical Review, Vol. 13, No. 1, p. 75-80 (2001)
(4) Kato, S., Miyamoto, O., Saitoh, Y., Tokuda, M., Hotta, T., Sunada, S.: Development of One-way Clutch-less 5-speed Automatic Transmission, JSAE Annual Congress Proceedings, No. 29-01, p. 13-18 (2001)

Author (organization or company)

Yoshiharu UCHIDA(Tochigi R&D Center)、Osahide MIYAMOTO(Tochigi R&D Center)、Tetsuya OTANI(Tochigi R&D Center)、Tetsuro MARUYAMA(Tochigi R&D Center)、Kazuaki SAKAI(Tochigi R&D Center)、Seiji TANIMOTO(Tochigi R&D Center)

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