930676 A New Approach to Finding Optimum Planetary Gear Trains for Automatic Transmissions Toshikazu Oshidari, Noboru Hattori, and Yoshirou Morimoto Nissan Motor Co., Ltd. Reprinted from: Automotive Transmissions and Drivelines (SP-965) International Congress and Exposition Detroit, Michigan March 1-5,1993 Downloaded from SAE International by University of Wisconsin - Madison , Sunday, September 09, 2018The appearance of the ISSN code at the bottom of this page indicates SAE's consent that copies of the paper may be made for personal or internal use of specific clients. This consent is given on the condition, however, that the copier pay a $5.00 per article copy fee through the Copyright Clearance Center, Inc. Operations Center, 27 Congress St., Salem, MA 01970 for copying beyond that permitted by Sections 107 or 108 of the U.S. Copyright Law. This consent does not extend to other kinds of copying such as copying for general distribution, for advertising or promotional purposes, for creating new collective works, or for resale. SAE routinely stocks printed papers for a period of three years following date of publication. Direct your orders to SAE Customer Sales and Satisfaction Depart- ment, Quantity reprint rates can be obtained from the Customer Sales and Satisfaction Department. To request permission to reprint a technical paper or permission to use copyrighted SAE publications in other works, contact the SAE Publications Group. No part of this publication may by reproduced in any form, in an electronic retrieval system or otherwise, without the prior written permission of the publisher. ISSN 0148-7191 Copyright 1993 Society of Automotive Engineers, Inc. Positions and opinions advanced in this paper are those of the author(s) and not necessarily those of SAE. The author is solely responsible for the content of the paper. A process is available by which discussions will be printed with the paper if it is published in SAE transactions. For permission to publish this paper in full or in part, contact the SAE Publications Group. Persons wishing to submit papers to be considered for presentation or publication through SAE should send the manuscript or a 300 word abstract of a proposed manuscript to: Secretary, Engineering Activity Board, SAE. Printed in USA 90-1203B/PG All SAE papers, standards, and selected books are abstracted and indexed in the SAE Global Mobility Database. Downloaded from SAE International by University of Wisconsin - Madison , Sunday, September 09, 2018930676 A New Approach to Finding Optimum Planetary Gear Trains for Automatic Transmissions Toshikazu Oshidari, Noboru Hattori, and Yoshirou Morimoto Nissan Motor Co., Ltd. ABSTRACT There has been a growing need to develop more compact automatic transmissions with a greater number of speeds for better fuel economy and better driveability. This study investigated a method for determining suitable planetary gear trains for today's transmissions. A computer program has been developed for application to five-speed transmissions consisting of two planetary gearsets. By analyzing various gear train possibilities, the program can identify which gearsets are suitable for different conditions, including the number of speeds, the number of binding elements, topological suitability and other factors. 1. ANALYTICAL THEORY A planetary gear train, consisting of N number of planetary gearsets, can have different gear system configurations depending on how engagement of the rotating elements is accomplished. The rotating ele- ments referred to here include the sun gear, carrier and ring gear of each planetary gearset, as well as the input and output shafts and case. Two types of engagement can be considered - ordinary engagement and discon- tinuous engagement through the action of the binding elements, i.e., clutches and brakes. Since two types of engagement are possible for each combination of 3 N + 3 ele