Tribology and Lubricants

Korean Tribology Society (한국트라이볼로지학회)
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Experimental Assessment of Drag Torque of Wet Clutch

습식 클러치 드래그 토크 특성의 실험적 평가

  • Kim, Hansol (School of Mechanical Engineering, University of Ulsan) ;
  • Chung, Koo-Hyun (School of Mechanical Engineering, University of Ulsan)
  • Received : 2017.09.15
  • Accepted : 2017.11.18
  • Published : 2017.12.31
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Abstract

Currently, fuel efficiency becomes one of critical issues for automotive industries as concerns about environmental and energy problems grow. In an automatic transmission of an automobile, a drag torque due to a viscous drag of a fluid between friction and clutch plates is one of factors that degrade fuel economy. In this work, the drag torque characteristics of a wet clutch was experimentally investigated with respect to rotational speed, temperature of automatic transmission fluid (ATF), and gap between friction and clutch plates. The experimental results showed that drag torque increases to a certain level, and then decrease to the steady state value with increasing rotational speed. This behavior may be associated with two-phase flow of air and ATF at gap between friction and clutch plates. Also, it was found that the maximum drag torque value decreased as ATF viscosity decreases with increasing temperature. However, it was shown that the point at which the maximum drag torque occurs was not significantly affected by the ATF temperature. In addition, maximum drag torque was found to decrease as the gap between friction and clutch plates increased from 0.1 mm to 0.2 mm. Furthermore, it was observed that the generation of maximum drag torque was delayed as the gap increased. The outcomes of this work are expected to be helpful to gain a better understanding of drag torque characteristic of a wet clutch, and may therefore be useful in the design of wet clutch systems with improved performance.

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References

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