JSAE 20030331 SAE 2003-01-1973 Analysis of the Various Factors Affecting Drag Torque in Multiple-Plate Wet Clutches Hisanao Kitabayashi, Chen Yu Li, Henry Hiraki Dynax Corporation 2003 JSAE/SAE International Spring Fuels & Lubricants Meeting Yokohama, Japan May 19-22,2003 10-2 Gobancho,Chiodaku, Tokyo 102-0076 Japan Tel:+81-3-3262-8211 Fax:+81-3-3261-2204 Downloaded from SAE International by University of Minnesota, Tuesday, July 31, 2018Notice about photocopy In order to photocopy any works from this publication, you or your organization must obtain permission from the following organization which you has been delegated for copyright for clearance by the copyright owner of this publication. Except in the U.S.A. Japan Academic Association for Copyright Clearance (JAACC) 6-41 Akasaka 9-chome, Minato-ku, Tokyo 107-0052 Japan TEL: 81-3-3475-5618 Fax: 81-3-3475-5619 E-mail:[email protected] In the U.S.A. Copyright Clearance Center, Inc. 222 Rosewood Drive, Danvers, MA 01923 U.S.A. Phone: 1-978-750-8400 Fax:1-978-750-4744 Copyright © 2003 Society of Automotive Engineers of Japan, Inc. Downloaded from SAE International by University of Minnesota, Tuesday, July 31, 2018JSAE 20030331 SAE 2003-01-1973 Analysis of the Various Factors Affecting Drag Torque in Multiple-Plate Wet Clutches Hisanao Kitabayashi, Chen Yu Li, and Henry Hiraki Dynax Corporation Copyright © 2003 Society of Automotive Engineers of Japan, Inc. ABSTRACT Experiments were conducted to study the effects of design factors of clutch packs on drag torque. From the test results, the design factors with a large effect were facing area and wave height. At high rotational speeds, automatic transmission fluid (ATF) flow rates and the number of grooves also had a significant effect. At low rotational speeds, since drag torque increased linearly with increasing speed, the results were compared to calculated values using theoretical equations based on Newton's law of viscosity. Furthermore, it was confirmed through visualization experiments of ATF flow on the rotating facing surface that the ATF completely covered the surface at low rotational speeds and that air mixed with the ATF at high rotational speeds. INTRODUCTION There is currently a strong demand in the automotive industry for improving energy efficiency in order to help protect the environment. One possible countermeasure for attaining this goal is to reduce drag torque in automatic transmissions (A/T). The drag torque mentioned in this paper refers to the torque transmitted from the driving plates to the driven plates during disengagement and is one of the causes of energy loss. Numerous papers have been written on the subject including studies on the differences in usage conditions and their effects on drag torque [1] and studies on the mechanisms that produce drag torque [2]. When the clutch is in a disengaged mode, since the friction plates and separator plates generally rotate at different speeds, the shearing force of the ATF is believed to cause drag torque. In this paper, the effects of various design factors on drag torque are evaluated. CLUTCH PACK STRUCTURE Figure 1 shows a configuration for a typical A/T clutch pack currently in production. 1 The clutch pack alternates a number of friction plates with separator plates. The former are splined to the clutch hub; the latter are splined to the clutch drum. The ATF that is supplied from an oil pump travels through the shaft of the clutch hub, flows radially between the friction plates and separator plates by centrifugal force, and is discharged through the oil holes of the clutch drum. TEST EQUIPMENT AND TEST CONDITIONS DRAG TORQUE TESTER Figure 2 shows the drag torque tester designed and developed by our company specifically for measuring drag torque. Downloaded from SAE International by University of Minnesota, Tuesday, July 31, 2018This drag torque teste