1、Innovations IN AUTOMOTIVE TRANSMISSION ENGINEERING Martin G. GabrielInnovations in Automotive Transmission Engineering Martin G. Gabriel Warrendale, Pa. Copyright 2004 SAE International eISBN: 978-0-7680-5529-0All rights reserved. No part of this publication may be reproduced, stored in a retrieval
2、system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. For permission and licensing requests, contact: SAE Permissions 400 Commonwealth Drive Warrendale, PA 15096-0001 USA E-mail: permissionssae
3、.org Tel: 724-772-4028 Fax: 724-772-4891 For multiple print copies, contact: SAE Customer Service E-mail: CustomerServicesae.org Tel: 877-606-7323 (inside USA and Canada) 724-776-4970 (outside USA) Fax: 724-776-1615 ISBN 0-7680-0995-2 Library of Congress Control Number: 2001099454 Copyright 2004 SAE
4、 International Positions and opinions advanced in this book are those of the author(s) and not necessarily those of SAE. The author is solely responsible for the content of this book. SAE Order No. T-109 Printed in the United States of America.Other SAE titles of interest: Electronic Transmission Co
5、ntrols By Ronald K. Jurgen (Order No. PT-79) The Motor Vehicle Edition 13 By K. Newton, W. Steeds, and T.K. Garrett (Order No. R-298) Vehicle and Engine Technology By Heinz Heisler (Order No. R-233) Automotive Handbook Edition 5 (Order No. BOSCH5) Special Publication from the 2003 SAE World Congress
6、: Transmission phone (724) 776-4970; fax (724) 776-0790; e-mail CustomerServicesae.org; website http:/store.sae.org.Contents Acknowledgments 9 Preface 11 Chapter One Some History! 13 Chapter Two The Transmission in Its Environment 17 Chapter Three The Transmission: An Integral Part of the Vehicle Po
7、wertrain 19 Rear-Wheel Drive (RWD) 19 Front-Wheel Drive (FWD) 20 Four-Wheel Drive (4WD) 21 Chapter Four Transmission Types 23 Manual-Step Layshaft Transmission 24 Automated Shift Transmission (AST) 25 Clutch/Flywheel Startup Device 26 Fluid Coupling Transmission 28 Torque Converter Transmission 29 C
8、ontinuously Variable Transmission (CVT) with Belt or Chain Variator 33 Continuously Variable Transmission (CVT) with Toroidal Variator 36 Continuously Variable Transmission (CVT) Hydrostatic 38 The Hybrid 39 Power-Split Configuration 39 Chapter Five Gearing the Transmission 43 The Vehicle Applicatio
9、n 44 Packaging Space 46 The Gearing Arrangement 46 Torque Multiplication Range 49 5“Elegant,“ Appropriate Ratio Steps 50 Shift Controls and Logic 50 Interface with Engine Controls 51 Lubrication 51 External Transmission Controls 52 Minimum Gear Noise and/or Whine 52 Gear Durability 52 Manufacturing
10、Facility Requirements 52 Chapter Six The Clutches of Change 55 Chapter Seven Transmission Controls 59 Chapter Eight Performance Attributes 63 Chapter Nine Transmission Power Needs 67 Chapter Ten Transmission Efficiency and Internal Component Power Losses 71 Chapter Eleven Harnessing Noise, Vibration
11、, and Harshness (NVH) 75 Chapter Twelve The Transmission Is “Cool“ 77 Chapter Thirteen Transmission Fluid and Lubrication 81 Chapter Fourteen Transmission Sealing Considerations 83 Chapter Fifteen Transmission Life Cycle and Sustainable Development 87 Chapter Sixteen The Measurables 89 Chapter Seven
12、teen The “New“ Transmission 99 Appendix One Significant Transmission Innovations 107 6List of Acronyms 111 About the Author 113 7Acknowledgments I wish to express my thanks to my wonderful wife, Marie, for her support and encour- agement in preparing this document. I am indebted to my daughter, Jean
13、ne Heilman, for her precious time and inspiration in the proofreading. Many others have contrib- uted, including Doug Cameron, Robert Cherrnay, Wayne Colonna, Don Fergle, Michael Imirie, V.J. Jandasek, Burt Martin, Walter Muench, Bruce Palamsky, R.C. Roethler, Karl Schneider, and Bruce Simpson. I wi
14、sh to credit David Burhans, DLB Industrial Design, who created the excellent graphics. I appreciate the help of Martha Swiss of the SAE International staff. 9Preface An automotive transmission is broad ranging, strong but invisible within its own environment, the vehiclelike a tiger in its native ha
15、unts. For years, engineers have been developing transmissions, mated with engines, to produce the optimum vehicle powertrain. For all of their thousands of creative mechanisms and patented ideas, the transmission engineers inventive genius has yet to meet all the needs of the customer and of society
16、. The automatic transmission has been in active development since the late 1930s. To commemorate the fiftieth anniversary of the automatic transmission, in March 1985, SAE International sponsored a panel discussion during its annual Congress held in Detroit, Michigan. Industry pioneers in the field
17、discussed the latest transmission developments as well as the technical progress of the entire industry. And it is a major industry, currently measured in billions of dollars. This book is designed to provide background and cohesive support for the manager who may have planning responsibility for di
18、recting the application of a transmission for a future vehicle application. Historical information is briefly reviewed as a basis for the state of development of current and future transmissions. Knowledge of past efforts helps to preclude repeating problems of the past. The format evolves naturally
19、 to the subject of transmissions of the future, identified as the “new“ transmission. New transmission concepts are examined and tested to shed light on ways the engi- neer can help to meet the demands of the customer of tomorrow. A transmission may take many forms and has various applications; ther
20、efore, for the purpose of the discussion in the following pages, some criteria have been established. First, the fundamental purpose of a transmission, as discussed herein, is to provide a cost-effective, efficient connection between a vehicle power source and its driving wheels. At first glance, th
21、is seems like a relatively straightforward objective. How- ever, after vehicle criteria are established, some of which may appear to conflict among themselves, the problems to engineer a successful transmission, which will be accepted by the motoring public for a sufficient number of years to make i
22、t a profit- able venture, may be quite formidable. The best example of conflicting criteria is to 11economically produce a higher-performance vehicle enginetransmission with no compromise in fuel economy. As the following pages show, that ongoing objective is being met. The discussion in the followi
23、ng pages will be limited to transmissions in passenger car or light truck applications, primarily in North America, to define a manageable scope of this vast and interesting subject. 12Chapter One Some History! An early MercuryEdselLincoln technical service manual, in its description of a transmissi
24、on, simply stated that a transmission is a device for adapting available engine power to road and load conditions. Far from a simple device, the transmission developed from a history of innovation that established its viability while remaining out of sight and “out of earshot“ (see Appendix One). To
25、day, following years of development of automotive vehicles and their powertrains, we know that a transmission can be described by its role in many scenarios. Impor- tant characteristics, such as vehicle fuel economy, vehicle performance, and quality and reliability, to name a few, immediately come t
26、o mind. These and others will be identified and sorted out in the following chapters. Some characteristics affect the customer and driver of the vehicle directly. Others, such as fabrication complexity and cost, will directly affect the transmission engineer and manufacturer; however, the eventual p
27、urchaser of the vehicle is still affected, albeit indirectly. Therefore, how can management, and particularly the transmission engineer, favorably impact these issues before they become unmanageable or unacceptably costly? In any event, over the years, after many transmission reiterations and billio
28、ns of dollars invested, are we to find out that the early definition as previously stated is still the most accurate? A review of the many transmission designs that have been implemented over the years reveals some interesting trends. Initial design approaches encompassed mechanisms to provide suffi
29、cient torque capacity to meet the torque output of the engine. Thus, the physical shape and overall dimensions of the transmission external case were defined. Then, with minor compromises, the vehicle underbody and connecting link- age would be adapted to accept that configuration. In early designs,
30、 objectives such as performance and fuel economy were subrogated by customer convenience and smooth performance, compared with those of manual transmissions. Acceptable vehicle performance was attained by employing sufficiently 13large engines with their correspondingly large displacements, as well
31、as large drive gear ratios to ensure mobility over the common road grades. Maximum vehicle speed became a by-product of so-called engine redline limitations and overall drive ratios. Although the first transmissions developed torque multiplication deemed adequate for acceptable vehicle acceleration,
32、 whether by means of stepped gearing or belt or trac- tion drive methods, the demand for driver convenience would define the parameters of the early automatic transmission. However, compromised vehicle performance or jerky shifting often was the result, discouraging full acceptance by the customer.
33、The marketing objectives of the vehicle and the overall vehicle powertrain arrange- ment dictate transmission configuration. A review of vehicle and transmission design history exemplifies certain objectives and compromises. For example, the well-known Ford Model T employed a front longitudinal engi
34、ne location, with the transmission driving the axle and rear wheels by means of a longitudinal driveshaft. This rear- wheel-drive example of modular vehicle design featured the outstanding advantages of easily assembled components and dealer servicing. These features were appreci- ated by service te
35、chnicians and home-garage repairmen alike, in comparison to the compact designs of today. Rear-wheel-drive vehicles performed their jobs well and are an economic success even today for various design and performance reasons. A lengthy period of successful production rear-wheel-drive vehicles ensued,
36、 however with interruptions of new driving features, to be discussed later. Then, around 1959, the high-production British Mini introduced the transverse enginetransmission, driv- ing the vehicle front wheels. The advantages of component integration, better con- trolled enginetransmission fabricatio
37、n, vehicle packaging, and operating efficiency immediately became popular with the motoring public. Vehicle driving advantages, such as handling under snowy road conditions, ensured the popularity of front-wheel drive. Limitations such as greater vehicle weight distribution on the front wheels had t
38、o be addressed. New servicing techniques had to be developed. It was natural that most early transmissions incorporated gearing to provide torque multiplication to accelerate the vehicle. The fixed nature of gearing has led to the incorporation of gear steps and an ancillary manual mechanism to enab
39、le the shifting from one gear ratio to another. It will be shown that alternative transmission mecha- nisms, such as belt and traction drives, can eliminate the gear steps and the associated potential jerkiness. 14Geared transmissions have retained much of their acceptance since those early days. Ir
40、onically, it is not because of their simplicity but because of their durability and inher- ent efficiency. Correct gear-teeth design facilitates torque transfer by rolling tooth contact. Rolling action is practically frictionless, unlike transfer by friction belts or traction drives. And without sig
41、nificant friction, gearing provides the opportunity for excellent durability, thereby compensating for the inflexibility of the gearing. This will be discussed further in subsequent pages. A review of developments over the years shows that more than 30 different transmis- sion designs were produced
42、in relatively high volumes, not counting heavy-truck, off-road, and specialty vehicles. Many of these are described in detail by P.M. Heldt 1-1, Phillip G. Gott 1-2, and others. Common features were as follows: A clutch or fluid member to connect the transmission to the engine A torque multiplicatio
43、n mechanism (usually a planetary geartrain) A device by which the driver controlled the transmission, engine, and vehicle A sealed case structure to house the transmission and ancillary components These devices included shift mechanisms and hydraulic fluid systems for control, lubrication, and cooli
44、ng. With these integral componentsand with provisions for monitoring vehicle speed, engine power, and speedwas born the modern automatic transmission. Of particular interest to us, however, are the significant new developments over the years and their impact on todays transmissions and the transmiss
45、ion design of the future. A chronological look may begin with the significant impact of viable methods for shifting gears. Back in 1891, Emile Levassor was credited with a patent using exter- nal gears on parallel shafts progressively engaged and disengaged. Although this fea- ture made the manual t
46、ransmission more acceptable to the average motorist at that time, it was soon replaced by L. Renaults design that transmitted power in direct gear without going through an engaged gearset with its associated losses. This basic concept prevailed until another significant innovation, called the Synchr
47、omesh trans- mission, was produced by Cadillac in 1928. No longer would the driver have to deal 15with the clashing of gears. The following pages will develop how electronics has facilitated shifting from gear to gear more smoothly, more reliably, and, most impor- tantly, executing the shifts at the
48、 best time for maximum vehicle performance or for fuel economy. Probably the next most significant development was the single plate clutch mecha- nism connecting the transmission to the engine. Other clutch designs came in the form of electromagnetic clutches, and multiple-plate dry and wet friction
49、 clutches. Subsequently, the fluid coupling appeared on the scene, first with the manual gearbox. With the advent of hydraulically augmented shifting and electronics, the clutch and gearbox drivetrain has become less popular. Thus was born the high-production fluid coupling automatic transmission such as the early General Motors Hydramatic, with three simple gearsets, introduced around 1940. That gradually was superseded by various configurations of torque converter transmissions that contained four, five, or more individual elements or integral geared arrangem
