International Journal of Automotive Technology

, Volume 15, Issue 1, pp 125–134 | Cite as

Analysis of the shifting behavior of a novel clutchless geared smart transmission

  • S. J. Kim
  • C. Song
  • K. -S. Kim
  • Y. -S. YoonEmail author


Conventional geared transmissions use some kinds of clutches to control the power flow from an internal combustion engine to the driveline while shifting gears. However, the shifting performance is seriously affected by the clutch engagement and an unavoidable drop in the torque may occur when the clutch is disconnected. Moreover, wear of the clutch, the need for hydraulic equipment, and the load limit may together aggravate the limits of the clutch system. For this reason, as a novel transmission without a clutch, the clutchless geared smart transmission (henceforth CGST) is proposed by our research team. The CGST controls the power flow in a multiple-input gear-train by controlling the electric motor attached to the planetary gear system. However, no CGST has been realized in an actual vehicle thus far, and the performance has been predicted only theoretically. In this research, we analyzed the achievable performance based on a developed CGST dynamic model with a typical CGST structure. In addition, a CGST gear-shifting algorithm is proposed for use with the dynamic model. From the simulation results, the CGST does not show an abrupt drop in its torque or oscillation while shifting gears due to the absence of a discontinuous power flow. The developed dynamic model can serve as a performance reference for the CGST. Moreover, it can be used as a simulation tool for developing a gear-shifting control logic scheme.

Key Words

Clutchless geared smart transmission (CGST) Dynamic model Gear shifting Planetary gear system Hybrid transmissions 


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Copyright information

© The Korean Society of Automotive Engineers and Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • S. J. Kim
    • 1
  • C. Song
    • 1
  • K. -S. Kim
    • 1
  • Y. -S. Yoon
    • 1
    Email author
  1. 1.School of Mechanical, Aerospace and System EngineeringKAISTDaejeonKorea

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