Case 1:17-cv-00770-JDW-MPT Document 120-7 Filed 11/17/22 Page 1 of 53 PageID #:
`13177
`
`EXHIBIT T
`
`

`

`. S7l
`Case 1:17-cv-00770-JDW-MPT Document 120-7 Filed 11/17/22 Page 2 of 53 PageID #:
`13178
`
`(^
`
`MASe
`
`UCRL-15037
`
`CONTINUOUSLY VARIABLE TRANSMISSIONS:
`THEORY AND PRACTICE
`
`August 1979
`
`Norman H. Beachley
`Andrew A. Frank
`
`College of Engineering
`University of Wisconsin, Madison
`
`n LAWRENCE
`
`UVERMORE
`LABORATORY
`
`vmrnm
`
`IP THIS 8ocu«arr ii mmm
`
`

`

`Case 1:17-cv-00770-JDW-MPT Document 120-7 Filed 11/17/22 Page 3 of 53 PageID #:
`13179
`
`NOTICE
`
`This report was prepared as an account of work sponsored by an agency
`of the United States Government. Neither the United States Government
`nor any agency thereof, or any of their employees, makes any warranty,
`expressed or implied, or assumes any legal Uability or responsibility for
`any third party's use, or the results of such use, of any information, ap(cid:173)
`paratus, product or process disclosed in this report, or represents that its
`use by such third party would not infringe privately owned rights.
`
`Reference to a company or product name does not imply approval or
`recommendation of the product by the University of California or any
`U.S. Government agency to the exclusion of others that may be suitable.
`
`This work was supported by the United States Nuclear Regulatory Commission under a Memorandum
`ot Understanding with the United States Department of Energy.
`
`Available from National Technical Information Service Springfield, Virginia 22161
`
`

`

`Case 1:17-cv-00770-JDW-MPT Document 120-7 Filed 11/17/22 Page 4 of 53 PageID #:
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`
`DISCLAIMER
`
`This report was prepared as an account of work sponsored by an
`agency of the United States Government. Neither the United States
`Government nor any agency Thereof, nor any of their employees,
`makes any warranty, express or implied, or assumes any legal
`liability or responsibility
`for
`the accuracy, completeness, or
`usefulness of any information, apparatus, product, or process
`disclosed, or represents that its use would not infringe privately
`owned rights. Reference herein to any specific commercial product,
`process, or service by trade name, trademark, manufacturer, or
`otherwise does not necessarily constitute or imply its endorsement,
`recommendation, or favoring by the United States Government or any
`agency thereof. The views and opinions of authors expressed herein
`do not necessarily state or reflect those of the United States
`Government or any agency thereof.
`
`

`

`Case 1:17-cv-00770-JDW-MPT Document 120-7 Filed 11/17/22 Page 5 of 53 PageID #:
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`DISCLAIMER
`
`
`Portions of this document may be illegible in
`electronic image products. Images are produced
`from the best available original document.
`
`
`

`

`Case 1:17-cv-00770-JDW-MPT Document 120-7 Filed 11/17/22 Page 6 of 53 PageID #:
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`Distribution Category
`I IP T ilfa 'I Ih
`
`m
`
`LAWRENCE UVERMORE LABORATORY
`University of Caffomia/Livermore, Califomia/94550
`
`UCRL-15037
`
`CONTINUOUSLY VARIABLE TRANSMISSIONS:
`THEORY AND PRACTICE
`
`Norman H. Beachley
`Andrew A. Frank
`College of Engineering, University of Wisconsin, Madison
`
`Manuscript date: August 1979
`
`- UlbULAIMbK •
`This book was prepared as an ac
`nt ot work sponsored by an agency of the United States Government
`Neither the United Stales Gove
`lent nor any agency thereof nor any of their employees makes any
`warranty express or
`implied
`r assumes any
`legal
`liability or responsibility
`for
`the accuracy
`completeness or usefulness
`any
`information apparatus product
`or process disclosed or
`infringe privately owned rights Reference herein to any specific
`j that Its use would not
`lal product process or service by trade name
`trademark manufacturer or otherwise does
`i endorsement
`recommendation or favoring by the United
`States Government or any agency thereof The views and opinions of authors expressed herein do not
`necessarily state or reflect those of the United States Government or any agency thereof
`
`1 X1
`
`8BUJJ8MTI0K OF THIS
`
`flflCI/Wdf
`
`tf Umli^
`
`

`

`Case 1:17-cv-00770-JDW-MPT Document 120-7 Filed 11/17/22 Page 7 of 53 PageID #:
`13183
`
`FORKWORD
`
`This report analyzes transmissison concepts useful for vehicular
`
`applications that utilize mechanical energy storage.
`
`Authors Norman H. Beachley and Andrew A. Frank of the University of
`
`Wisconsin, Madison, conducted this work as consultants to the Lawrence
`
`Livermore Laboratory, Mecheuiical Energy Storage Project.
`
`The Mechanical Energy Storage Project is funded by the Department of
`
`Energy, Division of Energy Storage Systems.
`
`., Vit
`
`iv
`
`

`

`Case 1:17-cv-00770-JDW-MPT Document 120-7 Filed 11/17/22 Page 8 of 53 PageID #:
`13184
`
`CONTENTS
`
`Foreword
`
`Abstract
`
`«
`
`1. Introduction
`
`2. Automotive Applications of Continuously Variable Transmissions . .
`
`2.1 Conventional Automobiles
`
`2.2 Electric Automobiles
`
`2.3 Flywheel Automobiles
`
`iii
`
`1
`
`1
`
`2
`
`2
`
`2
`
`3
`
`3. Design Categories of Continuously Variable Transmissions . . ..
`
`3
`
`3.1 Hydrostatic Transmissions
`
`3.2 Traction Drive
`
`3.2.1 V-Belt Traction Drives
`
`3.2.2 Rolling Contact Traction Drives
`
`3.3 Overrunning Clutch Designs
`
`3.4 Electric Continuously Variable Transmissions
`
`3.5 Multispeed Gearbox With Slipping Clutch
`
`Continuously Variable Transmission
`
`4. Power-Split and Inverse Power-Split Principles
`
`4.1 Power-Split Principle
`
`4.2 Inverse Power-Split Principle
`
`4.3 Power Recirculation Mode in Regular Power-Split
`
`Continuously Variable Transmission
`
`5. Controls
`
`3
`
`5
`
`5
`
`7
`
`9
`
`11
`
`12
`
`13
`
`13
`
`16
`
`19
`
`20
`
`5.1 Continuously Variable Transmissions in Automobiles . . ..
`
`22
`
`5.1.1. Continuously Variable Transmissions
`
`in the Conventional Car
`
`•
`
`5.1.2. Continuously Variable Transmissions
`
`for the Flywheel Hybrid Car
`
`6. Summary
`
`Appendix A: Commercially Available Continuously
`
`23
`
`23
`
`26
`
`Variable Transmissions Suitable for Motor Vehicles . ..
`
`27
`
`Appendix B: Research and Development Programs for
`
`Continuously Variable Transmissions
`
`31
`
`V
`
`

`

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`
`LIST OF ILLUSTRATIONS
`
`Schematic diagram of a flywheel automobile
`
`Typical hydrostatic transmission
`
`Variable-diameter pulley V-belt continuously variable
`
`transmission
`
`Steel-block belt as used in the van Doorne
`
`Transmatic continuously variable transmission
`
`Rolling contact traction drive continuously
`
`variable transmissions
`
`Single linkage of the zero-max continuously
`
`variable transmission
`
`Simple electric transmission
`
`Schematic diagram of a multispeed gearbox with
`
`slipping clutch continuously variable transmission
`
`Illustration of the power-split continuously variable
`
`transmission principle
`
`Schematic diagram of a hydrostatic power-split continuously
`
`variable transmission
`
`Illustration of the inverse power-split continuously
`
`variable transmission principle
`
`Diagrams of regular and inverse power-split continuously
`
`variable transmissions, showing directions of
`
`rotation and of torque
`
`Schematic diagram of a regular power-split continuously
`
`variable transmission when operating in the power
`
`recirculation mode
`
`Simple manual system to control the speed ratio of a
`
`variable V-belt continuously variable transmission
`
`Schematic diagram of a hydrostatic transmission showing a
`
`manually controlled lever that gives direct speed ratio
`
`control
`
`Schematic diagram of the torque control system used in the
`
`University of Wisconsin flywheel automobile
`
`vi
`
`4
`
`4
`
`6
`
`7
`
`8
`
`10
`
`11
`
`12
`
`13
`
`14
`
`17
`
`18
`
`20
`
`21
`
`22
`
`25
`
`

`

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`
`CONTINUOUSLY VARIABLE TRANSMISSIONS:
`THEORY AND PRACTICE
`
`Norman H. Beachley
`
`Andrew A. Frank
`
`ABSTRACT
`
`This report examines and compares the five basic principles that can be
`
`used in continuously variable transmission (CVT) design; (1) hydrostatic;
`
`(2) traction drive (V-belt and rolling contact); (3) overrunning clutch;
`
`(4) electric; and (5) multispeed gearbox with slipping clutch.
`
`Appendix A discusses commercially available CVTs suitable for motor
`
`vehicles, and Appendix B describes research and development programs for CVTs.
`
`1. INTRODUCTION
`
`This report examines and compares the five basic principles that can be
`
`used in continuously variable transmission design (CVT). Appendix A describes
`
`commercially available CVTs suitable for motor vehicles.
`
`Basic terms used in this report are defined in this section.
`
`A CVT is a transmission having a speed ratio that can be varied
`
`continuously over its allowable range. Its speed ratio may take on any value
`
`between its operational limits, i.e., an infinite number of ratios are
`
`possible. A gearbox transmission, on the other hand, has a discrete number of
`
`fixed speed ratios.
`
`The term continuously variable transmission also usually implies that
`
`torque may be controlled independently of speed ratio and vice versa. In
`
`other words, the torque converter of the conventional automobile should not be
`
`considered a CVT because the speed ratio is set by the torque transmitted.
`
`The term infinitely variable transmission (IVT) means basically the same
`
`as CVT, with the added restriction that a speed ratio of zero must be
`
`available, i.e., it must be possible to have zero output velocity for any
`
`input speed producing an infinite ratio range. A CVT providing negative as
`
`1
`
`

`

`Case 1:17-cv-00770-JDW-MPT Document 120-7 Filed 11/17/22 Page 11 of 53 PageID #:
`13187
`
`well as positive speed ratios would also be considered an IVT since its range
`
`passes through a speed ratio of zero.
`
`Even though this definition of IVT is generally accepted, IVT is often
`
`used as a synonym for CVT by those not familiar with the difference.
`
`Ratio range is one of the most important parameters of a CVT in terms of
`
`characterizing it for possible applications. Ratio range is defined as the
`
`numerical ratio of the maximum to the minimum output speeds possible for a
`
`given fixed input speed. For example, if a CVT can be controlled to operate
`
`between 3000 and 1000 rpm for a given fixed input speed, its ratio range is
`
`3.0. Ratio range is usually more significant than the speed ratios
`
`themselves, since the latter can normally be adjusted if necessary by other
`
`components in the drive line (e.g., the rear axle ratio of an autcanobile).
`
`The ratio range of an IVT is infinite, since it is calculated as a finite
`
`ratio divided by zero.
`
`2. AUTOMOTIVE APPLICATIONS OF CONTINUOUSLY VARIABLE TRANSMISSIONS
`
`2.1 CONVENTIONAL AUTOMOBILES
`
`At any given vehicle speed, and for any needed propulsive force, a
`
`certain transmission ratio will provide maximum fuel economy for a given
`
`engine. In addition, for any given vehicle speed, one transmission ratio will
`
`permit maximum acceleration with that engine. Since a CVT with the proper
`
`ratio range can provide the desired transmission ratios, it is obviously
`
`attractive for automobiles from both economy and performance points of view.
`
`In fact, its use (if its efficiency is high and its ratio range wide enough)
`
`can make it possible to have both maximum economy and maximum performance in
`
`the same vehicle.
`
`2.2 ELECTRIC AUTOMOBILES
`
`Electric traction motors are even less versatile in terms of efficiency
`
`over the typical automobile required torque-speed range than internal
`
`combustion engines. An efficient CVT has the potential of improving the
`
`average efficiency and, therefore, range of an electric automobile.
`
`2
`
`

`

`Case 1:17-cv-00770-JDW-MPT Document 120-7 Filed 11/17/22 Page 12 of 53 PageID #:
`13188
`
`2.3 FLYWHEEL AUTOMOBILES
`
`For an automobile using an energy storage flywheel (Fig. 1 ), a CVT or IVT
`
`is not only desirable but essential. The speed of the flywheel cannot be
`
`controlled at will, but changes only slowly as energy is added or subtracted. A
`
`CVT is required to match the flywheel and vehicle speeds under all possible
`
`operating conditions. A typical mode of operation, acceleration, will find the
`
`car speed increasing while the flywheel is slowing down. The CVT must match the
`
`two speeds in a continuous manner. Furthermore, the driver must be able to
`
`control the torque being transmitted in order for the car to be driven in a
`
`conventional manner.
`
`To take full advantage of the flywheel concept, regenerative braking must
`
`be used, i.e., the system must allow kinetic energy of the car to be converted
`
`to flywheel kinetic energy. This kind of braking requires a CVT that can
`
`transmit power in both directions—to or from the flywheel.
`
`3. DESIGN CATEGORIES OF CONTINUOUSLY VARIABLE TRANSMISSIONS
`
`Many CVT designs have been proposed, and quite a number have been built,
`
`either as prototypes or as production versions. Some designs are so
`
`sophisticated it is difficult to determine how they operate from drawings or
`
`written descriptions. It is very useful, therefore, to describe and discuss the
`
`different categories into which the various CVTs fall. A few well-defined
`
`principles form the basis of all known CVT designs, and knowing the basic
`
`advantages and limitations of each principle will aid in the preliminary
`
`evaluation of any proposed CVT design.
`
`The following basic types of CVT are meant to cover all generic
`
`possibilities although it is possible that there are inventions unknown to us
`
`that use some entirely different principle. If one can find the proper category
`
`for any particular CVT, he can understand certain of its characteristics and
`
`features without a complete understanding of the mechanical details.
`
`3.1 HYDROSTATIC TRANSMISSIONS
`
`Hydrostatic transmissions transmit power through the use of high-pressure
`
`oil, typically at pressures up to about 5000 psi. A hydrostatic transmission
`
`(Fig. 2) consists of a hydraulic pump and hydraulic motor connected together by
`
`two hydraulic lines and with the other required hydraulic components (such
`
`^3
`
`

`

`Case 1:17-cv-00770-JDW-MPT Document 120-7 Filed 11/17/22 Page 13 of 53 PageID #:
`13189
`
`Engine calibrated
`for low emissions and
`low bsfc at
`full-throttle
`operation
`
`Standard rear
`axle assembly-
`
`CVT clutch
`(if required)
`
`Continuously
`variable
`transmission
`
`Driveshaft
`
`Flywheel
`package
`
`FIG. 1. Schematic diagram of a flywheel automobile,
`fuel consumption.)
`
`(bsfc is brake specific
`
`Variable
`swashplate ^^^^^3,
`
`Forward 1 Reverse
`
`Fixed
`swashplate-
`
`ifZZZZZA Low-pressure
`fluid WZZZZhi
`yz^^B^
`r ^^
`^ ^ £ _ ] ^ ^^
`V//7A "i°'-g"-° V//////y-
`
`Variable displacement pump
`
`Input
`shaft
`
`Fixed displacement motor
`Output
`shaft
`
`FIG. 2. Typical hydrostatic transmission.
`
`f4
`
`

`

`Case 1:17-cv-00770-JDW-MPT Document 120-7 Filed 11/17/22 Page 14 of 53 PageID #:
`13190
`
`as reservoir, check valves, and relief valves). The pump creates the
`
`hydraulic power (pressure and flow rate), and the motor converts the hydraulic
`
`power to mechanical power (torque and speed). The basic system is a CVT if
`3
`the pump is designed to have a displacement (in. /revolution) that can be
`
`varied. (Sonetimes the motor is also given a variable displacement to give
`
`additional versatility.)
`
`Straight hydrostatic transmissions (the power-split version will be
`
`discussed later) will almost always have a ratio range of infinity, i.e., be
`
`IVTs. (Since the stroke of the pump can be set to zero, the output speed of
`
`the motor will vary from zero to its maximum value.) The stroke of the pump
`
`can usually be reversed so that the hydraulic motor rotation can be either
`
`positive or negative. The torque of the hydrostatic transmission can be
`
`reversed (the high-pressure line changing to the low-pressure line and vice
`
`versa), with the "pump" then acting as a motor and the "motor" as a pump.
`
`The hydrostatic transmission is thus quite versatile, and has a number of
`
`features desirable for an autcxnobile transmission. There are many commercially
`
`available units in sizes appropriate for automobiles. The major disadvantages
`
`are size, weight, and relative inefficiency (especially when compared to
`
`gears) of the straight hydrostatic transmission over a wide speed and torque
`
`range.
`
`3.2 TRACTION DRIVE
`
`Traction drive is a term applied to any device which transmits power
`
`through adhesive friction between two objects loaded against each other. A
`
`V-belt is one example; another is the use of metal elements rolling on one
`
`another. The concept is in contrast to the use of gears or chains, in which
`
`the coefficient of friction serves no useful purpose. Traction drive CVTs
`
`fall into two basic categories, V-belt drives and rolling contact drives, and
`
`it is useful to discuss the two separately.
`
`3.2.1 V-Belt Traction Drives
`
`A rubber V-belt drive with pulleys (sheaves) whose diameters may be
`varied is a CVT (Fig. 3) that can transmit power in either direction of
`rotation. If both pulleys are made variable, a ratio range of about 3.5 is
`
`5
`
`

`

`Case 1:17-cv-00770-JDW-MPT Document 120-7 Filed 11/17/22 Page 15 of 53 PageID #:
`13191
`
`Input
`
`zz
`
`TTT7 w Output
`
`FIG. 3. Variable-diameter pulley V-belt continuously variable transmission.
`
`typically achieved. Such drives are common for machine tools. In recent
`
`years they have been the most common type of transmission for snowmobiles,
`
`where they may transmit up to 50 hp or more. The DAF automobile, built in
`
`Holland (and currently owned by Volvo of Sweden), has used a rubber V-belt CVT
`
`for many years.
`
`The pulley diameters may be varied in various ways, depending on the
`
`ratio range desired and the type of control needed. A common scheme for
`
`machine tools is to have both pulleys variable with a fixed center distance,
`
`one pulley having its effective diameter set by a mechanical linkage, and the
`
`other one spring-loaded to provide automatic correspondence. Typical mobile
`
`applications set the ratio range as a function of demanded tiorque and speed,
`
`using mechanical control system devices to provide the desired relationships.
`
`A recent development is the Transmatic transmission based on a V-belt
`
`made of steel blocks joined by steel bands (Fig. 4 ). (This transmission is
`
`produced by van Doorne of Holland.)
`
`6
`
`

`

`Case 1:17-cv-00770-JDW-MPT Document 120-7 Filed 11/17/22 Page 16 of 53 PageID #:
`13192
`
`FIG. 4. Steel-block belt as used in the van Doorne Transmatic continuously
`
`variable transmission.
`
`3.2.2 Rolling Contact Traction Drives
`
`A number of CVT configurations work on the principle of rolling contact,
`
`usually two metal surfaces rolling on one another while lubricated with a
`
`special type of oil. By changing the effective radius of one or both
`
`surfaces, the speed ratio is varied in a continuous fashion.
`
`Several transmissions in this category are illustrated in Fig. 5. The
`
`simple concept shown in Fig. 5(a) was actually used in several early makes of
`
`automobiles (e.g., the 1909 Cartercar, the 1909 Sears Motor Buggy, and the
`
`1909 Orient Model BB Buckboard). The output wheel is moved on a splined shaft
`
`to different diameters on the input disk to set the desired speed ratio. The
`
`design is still in use on some makes of garden tractors.
`
`For the CVT of Fig. 5(b), a ring is moved back and forth to vary the
`
`speed ratio. The ring must be kept at the same angle so that the points of
`
`tangency will be the same distance apart.
`
`In the CVT of Fig. 5(c), a ball is used to transmit torque between the
`
`input and output disks. The ball can be moved as shown to increase the radius
`
`of contact on one disk while at the same time decreasing the radius on the
`
`other. In practice, a number of balls are used, located in a cage that is
`
`positioned to set the CVT ratio. The cage itself must be free to rotate about
`
`7
`
`

`

`Case 1:17-cv-00770-JDW-MPT Document 120-7 Filed 11/17/22 Page 17 of 53 PageID #:
`13193
`
`Input
`
`Input
`
`V
`
`S]
`
`K
`i
`i
`
`)
`
`r
`
`V
`
`(a) Simple concept
`
`Input
`
`Input
`
`-^
`
`Output
`
`(c) Ball
`
`Rim disk-
`
`Output
`
`Id) Two or more spherical elements
`
`Input
`
`Output
`
`Cone disk
`
`(e) Beier drive
`
`(f) Toroidal drive
`
`FIG. 5. Rolling contact traction drive continuously variable transmissions.
`
`8
`
`

`

`Case 1:17-cv-00770-JDW-MPT Document 120-7 Filed 11/17/22 Page 18 of 53 PageID #:
`13194
`
`its center line, to allow for the fact that the balls in this case will be at
`
`different radii. (Although it is not obvious by any means, a kinematic
`
`analysis will prove that all balls can transmit torque by a pure rolling
`
`action with no sliding required.)
`
`In the CVT of Fig. 5(d), two or more spherical elements are used to
`
`transmit torque between the input and output disks. Tilting the axles of the
`
`spheres will produce different rolling radii for the input and output contact
`
`#
`
`points.
`
`The Beier drive. Fig. 5(e), is based on rim disks with outer rims that
`
`make contact with cone disks at a variable radius. The distance between the
`
`input and output shafts is varied to make contact.
`
`Industrial CVTs with small horsepower capacities are available with
`
`designs based on Figs. 5(a) through 5(e) as well as other similar principles.
`
`The toroidal drive. Fig. 5(f), however, may be more nearly developed to the
`
`point of being practical for automobiles. Early work was done by General
`
`Motors in the 1920's and 30's, with the concept apparently losing out to the
`
`torque converter type of automatic transmission that is now virtually
`
`standard. In England, the toroidal drive is known as the Perbury Drive,
`
`apparently named after the man who invented or designed that particular
`
`version. At least two U.S. companies are now actively engaged in research and
`
`development of this particular concept: (1) Excelermatic, Inc., of Austin,
`
`Texas and (2) AiResearch Manufacturing Company, Garrett Corporation, Torrance,
`
`California. Various companies and private individuals are developing and
`
`promoting other rolling contact traction drive concepts.
`
`3.3 OVERRUNNING CLUTCH DESIGNS
`
`An overrunning clutch is a device that allows torque to be transmitted in
`
`one direction, but which overruns or freewheels if an attempt is made to apply
`
`torque in the opposite direction. A common example is the bicycle coaster
`
`brake (or corresponding freewheel of a 10-speed bike). Some CVTs use a
`
`combination of overrunning clutches and kinematic linkages.
`
`One of the simpler examples of this class of CVT, and one which is
`
`available commercially in smaller power ranges, is the Zero-Max. Figure 6
`
`illustrates the operating principle of a single linkage with four to eight
`
`such linkages normally being used. The rotating shaft at the left has an
`
`9
`
`

`

`Case 1:17-cv-00770-JDW-MPT Document 120-7 Filed 11/17/22 Page 19 of 53 PageID #:
`13195
`
`FIG. 6. Single linkage of the zero-max continuously variable transmission.
`
`eccentric for each linkage. This arrangement causes the power link to
`
`oscillate. With overrunning clutches (or ratchets), a one-directional
`
`rotation of the output shaft on the right is obtained. With multiple
`
`linkages, the resultant output motion, equal at any instant of time to the
`
`motion of the overrunning clutch that is rotating the fastest and therefore
`
`driving, is nearly uniform. The speed ratio is changed by moving point A of
`
`the control link.
`
`Other more sophisticated transmissions based on the same basic principle,
`
`but in sizes suitable for automobiles, have been proposed. Insufficient
`
`experimental data are available to adequately evaluate them.
`
`One important disadvantage of the ratchet type CVT is that it does not
`
`allow reverse torque; therefore a single such CVT cannot allow regenerative
`
`braking for a flywheel car. The only way to get regenerative braking is to
`
`put two such CVTs in parallel, but reversed with respect to each other. One
`
`would then be used for positive torque and the other for regenerative braking.
`
`10
`
`

`

`Case 1:17-cv-00770-JDW-MPT Document 120-7 Filed 11/17/22 Page 20 of 53 PageID #:
`13196
`
`3.4 ELECTRIC CONTINUOUSLY VARIABLE TRANSMISSIONS
`
`An electric generator motor combination makes a CVT (Fig. 7) that is in
`
`many respects analogous to the hydrostatic transmission. The generator
`
`converts mechanical power (torque and speed) to electrical power (voltage and
`
`current). The electric power is then fed to the motor, which converts it back
`
`to mechanical power. The continuously variable feature is achieved because of
`
`the lack of any rigid requirement on the relative speeds of the two electric
`
`machines and because the torque of the motor can be controlled by varying the
`
`voltage and/or the current of the generator. With proper component
`
`characteristics, the system will be an IVT, i.e., the motor can supply torque
`
`while motionless. Such a system can be based on either ac or dc power.
`
`The concept is attractive because of the versatility of electric motors
`
`in terms of torque and speed. Currently available electric machines capable
`
`of automobile level power are quite large and heavy, however. Efficiency
`
`drops off when they cire operated at conditions far removed from the design
`
`point. Another consideration is the complexity and efficiency of a controller
`
`that would allow the driver to control torque independently of vehicle speed.
`
`Research in the electric drive field is being conducted with these factors in
`
`mind.
`
`The electric CVT is readily adaptable to the power-split principle
`
`(Section 4.1).
`
`Control circuitry
`
`r^
`
`^
`
`[~^
`\J Input
`
`dc
`Electric
`generator
`
`dc
`Electric
`motor
`
`•^
`
`^
`Output
`
`FIG. 7. Simple e l e c t r ic
`
`transmission.
`
`11
`
`

`

`Case 1:17-cv-00770-JDW-MPT Document 120-7 Filed 11/17/22 Page 21 of 53 PageID #:
`13197
`
`3.5 MULTISPEED GEARBOX WITH SLIPPING CLUTCH
`
`CONTINUOUSLY VARIABLE TRANSMISSION
`
`A gearbox can operate only at discrete speed ratios. If a clutch is
`
`placed in series with the gearbox, however, its slippage can allow any speed
`
`ratio to be available, and the system can be considered to be a form of CVT
`
`(Fig. 8) because the torque can be controlled independently of the ratio. If
`
`enough gear ratios are available, the energy loss due to slippage is minimal.
`
`For example, if we ignore such things as bearing friction, a clutch that has
`
`15 percent slippage is 85 percent efficient.
`
`One major advantage of the slipping clutch concept is that it could be
`
`designed and developed in a straightforward manner with current technology.
`
`Some early experimental flywheel vehicles have operated on this principle.
`
`Some disadvantages are the high frequency of shifting required and the
`
`somewhat unknown factor of clutch wear. It is possible, however, to use a
`
`device that acts as a clutch (e.g., a hydrostatic pump with a controllable
`
`orifice between it and the reservoir) that would have virtually no wear.
`
`Input
`
`^
`
`5-Speed
`gearbox
`
`I Output
`
`—V-
`-^
`
`I i
`
`2-Speed box
`with clutches
`
`FIG. 8. Schematic diagram of a multispeed gearbox with slipping clutch
`continuously variable
`transmission.
`
`12
`
`

`

`Case 1:17-cv-00770-JDW-MPT Document 120-7 Filed 11/17/22 Page 22 of 53 PageID #:
`13198
`
`4. POWER-SPLIT AND INVERSE POWER-SPLIT PRINCIPLES
`
`4.1 POWER-SPLIT PRINCIPLE
`
`>'
`
`The power-split principle was developed to partially overcome the poor
`
`efficiency characteristics of certain CVTs. The basic idea is to send only
`
`part of the power through the continuously variable unit (CVU), with the
`
`remainder of the power going through a straight mechanical path (with higher
`
`efficiency). The two components of power are then added in a mechanical gear
`
`differential at the output of the power-split CVT. Figure 9 illustrates the
`
`basic concept.
`
`For a given input speed (w. ), we are essentially adding two velocities
`
`at the mechanical differential. With one of these fixed and the other
`
`variable, the output speed (o) i.) is variable and the overall system of
`
`Fig. 9 is a CVT. As is usually the case, however, we don't get something for
`
`nothing. In gaining higher efficiency, we suffer a reduction in ratio range.
`
`Figure 10 is another schematic of a power-split CVT, one which shows a
`
`little more detail. The mechanical differential is drawn as a bevel gear type
`
`(exactly the same principle as used in the drive axle differentials of
`
`automobiles) for ease of illustration, but a planetary or a spur gear type of
`
`Power
`input
`
`Mechanical
`shaft
`power
`
`Power
`to
`continuously
`variable
`unit
`
`Continuously
`variable
`unit
`
`Mechanical
`differential
`
`j|^
`
`Power
`from
`continuously
`variable
`unit
`
`Power
`output
`
`o ut
`
`FIG. 9. Illustration of the power-split continuously variable transmission
`
`principle.
`
`Where a basic CVT unit is used as part of a more complex CVT system it will
`
`be called a continuously variable unit in an attempt to avoid confusion.
`
`13
`
`

`

`Case 1:17-cv-00770-JDW-MPT Document 120-7 Filed 11/17/22 Page 23 of 53 PageID #:
`13199
`
`Indicates torque
`on shaft
`
`Indicates shaft
`speed
`
`^
`
`Z
`
`N
`
`Input
`shaft
`
`r
`'^
`
`f^
`
`Nr
`
`t
`
`Equations for
`differential:
`T i = T2
`T3 = T, + T2 = 2 T,
`N3 = y2{Ni + N 2)
`
`Differential jyj
`
`'31 2
`
`>
`
`I
`
`«
`
`!
`
`Driveshaft
`
`5
`
`-
`
`N
`'^3
`
`Ty
`
`t
`
`Rear
`axle
`
`5
`
`N.
`
`Hydrostatic
`transmission
`(CVU)
`
`A
`V
`
`N.
`
`FIG. 10. Schematic diagram of a hydrostatic power-split continuously variable transmission.
`
`

`

`Case 1:17-cv-00770-JDW-MPT Document 120-7 Filed 11/17/22 Page 24 of 53 PageID #:
`13200
`
`differential is a more logical choice for a practical design. (Planetary
`
`gearing is used in the Sundstrand and Orshansky power-split CVTs.) Note that
`
`Fig. 10 shows a gear ratio between the input shaft and the input to the CVU
`
`and also between the output of the CVU and the gear differential.
`
`To reduce the fraction of power going through the CVU (and thereby raise
`
`overall efficiency), we reduce its torque (which also allows its size to be
`
`reduced). But to satisfy the torque balance of the differential (T = T ),
`
`•
`
`a relatively large gear ratio (N_/N_) is needed. As this gear ratio
`
`increases, the effect of a given change in CVU output speed upon N
`
`decreases, resulting in a lower ratio range. (This explanation is based on
`
`the assumption that the speed characteristics of the CVU do not change
`
`appreciably with a change in size.)
`
`It is interesting to consider the type of application for which a
`
`power-split CVT is ideally suited. This would be an application where a
`
`device is to be run at a speed that is almost, but not quite, constant, and
`
`where the small speed changes must be made in a continuous manner. Certain
`
`components of paper-making machinery (e.g., large rolls) fit this category,
`
`since small speed adjustments are required to keep the proper tension in the
`
`paper as it runs through. The CVT ratio range may be reduced to 1.1 or less
`
`for such an application, meaning that only a small fraction of the power is
`
`transmitted by the CVU and the rest by mechanical shafts and gears.
`
`For an automobile, the loss in ratio range caused by using the
`
`power-split principle can be compensated by having a gearbox (or something
`
`comparable) in series. The gearbox-CVT then becomes a wide range continuous
`
`transmission system, with the CVT filling in the ratio gaps between gears. As
`
`an example, suppose we want to have an overall ratio range of 10.4 to 1, and
`
`we wish to accomplish this using a 4-speed gearbox and a power-split CVT in
`series. Then we find that y 10.4 = 1.8; therefore, each gear ratio of the
`fixed ratio transmission should vary from the adjacent one by a factor of 1.8;
`
`i.e., first gear will be 5.83, second gear will be 3.24, third gear will be
`
`«
`
`1.8, and fourth gear will be 1.0. The CVT must also have a ratio range of
`
`1.8. The overall transmission system ratio is then the CVT ratio multiplied
`
`by the fixed transmission ratio. Thus, in first gear the overall speed ratio
`
`varies from 10.4 to 5.83 with the CVT varying from 1.8 to 1, at which time the
`
`fixed transmission is shifted and the CVT set again to 1.8. The gear ratio in
`
`second gear then varies continuously from 5.83 to 3.24. Thus by changing
`
`15
`
`

`

`Case 1:17-cv-00770-JDW-MPT Document 120-7 Filed 11/17/22 Page 25 of 53 PageID #:
`13201
`
`gears in the fixed ratio transmission and letting the CVT vary back and forth
`
`the overall transmission system can vary continuously from 10.4 to 1.0 to 1.
`
`It is important to realize that this shifting and control can be automated
`
`very easily if the proper control