WO2017196787A1

WO2017196787A1 - Cvt with fixed and variable powerpaths

Info

Publication number: WO2017196787A1
Application number: PCT/US2017/031666
Authority: WO
Inventors: Joel Ls ADCOCK; Jeffrey M. DAVID; Gordon MCINDOE; Charles B. LOHR, III; Travis J. Miller; Sebastian J. PETERS
Original assignee: Dana Limited
Priority date: 2016-05-09
Filing date: 2017-05-09
Publication date: 2017-11-16

Abstract

Devices and methods are provided herein for the transmission of power in motor vehicles. Power is transmitted in a smoother and more efficient manner by splitting torque into two or more torque paths. A continuously variable transmission is provided with a ball variator assembly having an array of balls, a planetary gearset coupled thereto and an arrangement of rotatable shafts with multiple gears and clutches that extend the ratio range of the variator. In some embodiments, a locking clutch is operably coupled to the planetary gearset to selectively couple two of the elements of the planetary gearset during operation. Engagement of the locking clutch corresponds to a fixed ratio operating mode. Disengagement of the locking clutch corresponds to a variable ratio operating mode.

Description

CVT WITH FIXED AND VARIABLE POWERPATHS

RELATED APPLICATION

The present application claims the benefit of U.S. Provisional Application No. 62/333,632 filed on May 9, 2016, which are incorporated herein by reference in its entirety.

BACKGROUND

A driveline including a continuously variable transmission allows an operator or a control system to vary a drive ratio in a stepless manner, permitting a power source to operate at its most advantageous rotational speed.

SUMMARY

Provided herein is a continuously variable transmission including: a first rotatable shaft operably coupleable to a source of rotational power; a second rotatable shaft arranged coaxially with the first rotatable shaft, the first rotatable shaft and the second rotatable shaft forming a main axis; a ball-type variator assembly having a first traction ring assembly and a second traction ring assembly in contact with a plurality of balls, wherein each ball of the plurality of balls has a tiltable axis of rotation, the variator assembly is coaxial with the main axis, the first traction ring is operably coupled to the second rotatable shaft; a planetary gearset having a sun gear operably coupled to the first traction ring assembly, a planet carrier operably coupled to the first rotatable shaft, and a ring gear coupled to the second traction ring assembly; and a locking clutch operably coupled to the planet carrier.

Provided herein is a continuously variable transmission including: a first rotatable shaft operably coupleable to a source of rotational power; a second rotatable shaft arranged coaxially with the first rotatable shaft, the first rotatable shaft and the second rotatable shaft forming a main axis; a ball-type variator assembly having a first traction ring assembly and a second traction ring assembly in contact with a plurality of balls, wherein each ball of the plurality of balls has a tiltable axis of rotation, the variator assembly is coaxial with the main axis, the first traction ring is operably coupled to the second rotatable shaft; a planetary gearset having a sun gear operably coupled to the first traction ring assembly, a planet carrier operably coupled to the first rotatable shaft, and a ring gear coupled to the second traction ring assembly; and a locking clutch operably coupled to the ring gear and the sun gear.

Provided herein is a method of operating vehicle provided with a continuously variable transmission having a ball-type variator, the method including the steps of: operating a powersplit variator including: a first rotatable shaft operably coupleable to a source of rotational power; a second rotatable shaft arranged coaxially with the first rotatable shaft, the first rotatable shaft and the second rotatable shaft forming a main axis; a ball-type variator assembly having a first traction ring assembly and a second traction ring assembly in contact with a plurality of balls, wherein each ball of the plurality of balls has a tiltable axis of rotation, the variator assembly is coaxial with the main axis, the first traction ring is operably coupled to the second rotatable shaft; a planetary gearset having a sun gear operably coupled to the first traction ring assembly, a planet carrier operably coupled to the first rotatable shaft, and a ring gear coupled to the second traction ring assembly; and a locking clutch coupled to the planetary gearset; evaluating a command for fixed ratio operation;

commanding an engagement of the locking clutch; and commanding a disengagement of a variator actuator, the variator actuator coupled to the variator and configured to control a speed ratio of the variator.

Provided herein is a continuously variable transmission including: a first rotatable shaft; a second rotatable shaft arranged coaxially with the first rotatable shaft, the first rotatable shaft and the second rotatable shaft forming a main axis, the second rotatable shaft operably coupled to a source of rotational power; a ball-type variator assembly having a first traction ring assembly and a second traction ring assembly in contact with a plurality of balls, wherein each ball of the plurality of balls has a tiltable axis of rotation, the variator assembly is coaxial with the main axis, the first traction ring is operably coupled to the second rotatable shaft; a planetary gearset having a sun gear operably coupled to the first traction ring assembly, a planet carrier operably coupled to the first rotatable shaft, and a ring gear coupled to the second traction ring assembly; and a locking clutch operably coupled to the planet carrier.

Provided herein is a continuously variable transmission including: a first rotatable shaft; a second rotatable shaft arranged coaxially with the first rotatable shaft, the first rotatable shaft and the second rotatable shaft forming a main axis, the second rotatable shaft operably coupleable to a source of rotational power; a ball-type variator assembly having a first traction ring assembly and a second traction ring assembly in contact with a plurality of balls, wherein each ball of the plurality of balls has a tiltable axis of rotation, the variator assembly is coaxial with the main axis, the first traction ring is operably coupled to the second rotatable shaft; a planetary gearset having a sun gear operably coupled to the first traction ring assembly, a planet carrier operably coupled to the first rotatable shaft, and a ring gear coupled to the second traction ring assembly; and a locking clutch operably coupled to the ring gear and the sun gear.

Provided herein is a vehicle driveline including a power source, a variable transmission of any of described herein drivingly engaged with the _y power source, and a vehicle output drivingly engaged with the variable transmission.

Provided herein is a method of operating vehicle provided with a continuously variable transmission having a ball-type variator, the method including the steps of: operating a powersplit variator having: a first rotatable shaft operably coupleable to a source of rotational power; a second rotatable shaft arranged coaxially with the first rotatable shaft, the first rotatable shaft and the second rotatable shaft forming a main axis; a ball-type variator assembly having a first traction ring assembly and a second traction ring assembly in contact with a plurality of balls, wherein each ball of the plurality of balls has a tiltable axis of rotation, the variator assembly is coaxial with the main axis, the first traction ring is operably coupled to the second rotatable shaft; a shift actuator operably coupled to the ball-type variator, the shift actuator configured to control a ratio of the ball-type variator, the shift actuator configured to engage and disengage the ball-type variator; a locking clutch coupled to the first rotatable shaft and the second rotatable shaft; evaluating a command for fixed ratio operation; commanding an engagement of the locking clutch; and commanding a disengagement of the shift actuator.

Provided herein is a continuously variable transmission comprising: a first rotatable shaft; a second rotatable shaft arranged coaxially with the first rotatable shaft, the first rotatable shaft and the second rotatable shaft forming a main axis, the second rotatable shaft operably coupleable to a source of rotational power; a ball-type variator assembly having a first traction ring assembly and a second traction ring assembly in contact with a plurality of balls, wherein each ball of the plurality of balls has a tiltable axis of rotation, the variator assembly is coaxial with the main axis, the first traction ring is operably coupled to the second rotatable shaft; a planetary gearset having a sun gear operably coupled to the first traction ring assembly, a planet carrier operably coupled to the first rotatable shaft, and a ring gear operably coupled to the second traction ring assembly; and a first locking clutch operably coupled to the ring gear and a grounded member; and a second locking clutch operably coupled the ring gear and the second traction ring assembly.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

Novel features of the preferred embodiments are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present embodiments will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the embodiments are utilized, and the accompanying drawings of which:

Figure 1 is a side sectional view of a ball-type variator.

Figure 2 is a plan view of a carrier member that is used in the variator of Figure 1. Figure 3 is an illustrative view of different tilt positions of the ball-type variator of Figure 1.

Figure 4 is a schematic diagram of a planetary powersplit continuously variable transmission.

Figure 5 is a schematic diagram of a multiple mode continuously variable transmission having the planetary powersplit continuously variable transmission of Figure 4.

Figure 6 is a table depicting operating modes of the continuously variable transmissions depicted in Figure 5.

Figure 7 is a schematic diagram of a powersplit variator having a locking clutch.

Figure 8 is a schematic diagram of another powersplit variator having a locking clutch.

Figure 9 is a schematic diagram of yet another powersplit variator having a locking clutch.

Figure 10 is a block diagram of a transmission control system that is used with the any of the powersplit variators or continuously variable

transmissions disclosed herein.

Figure 11 is a flow chart depicting a control process that is implemented in the transmission control system of Figure 10.

Figure 12 is a schematic diagram of a variator having a locking clutch coupled between a first traction ring assembly and a second traction ring assembly.

Figure 13 is a schematic diagram of a powersplit variator having two locking clutches.

Figure 14 is a table depicting operating modes of the powersplit variator of Figure 13.

Figure 15 is a schematic diagram of another powersplit variator having two locking clutches.

Figure 16 is a table depicting operating modes of the powersplit variator of Figure 15.

Figure 17 is a schematic diagram of yet another powersplit variator having two locking clutches. Figure 18 is a table depicting operating modes of the powersplit variator of Figure 17.

Figure 19 is a schematic diagram of a powersplit variator having three locking clutches.

Figure 20 is a table depicting operating modes of the powersplit variator of Figure 19.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments will now be described with reference to the accompanying figures, wherein like numerals refer to like elements throughout. The terminology used in the descriptions below is not to be interpreted in any limited or restrictive manner simply because it is used in conjunction with detailed descriptions of certain specific embodiments. Furthermore,

embodiments includes several novel features, no single one of which is solely responsible for its desirable attributes or which is essential to practicing the embodiments described.

Provided herein are configurations of CVTs based on a ball type variators, also known as CVP, for continuously variable planetary. Basic concepts of a ball type Continuously Variable Transmissions are described in United States Patent No. 8,469,856 and 8,870,711 incorporated herein by reference in their entirety. Such a CVT, adapted herein as described

throughout this specification, comprises a number of balls (planets, spheres) 1 , depending on the application, two ring (disc) assemblies with a conical surface in contact with the balls, an input traction ring 2, an output traction ring 3, and an idler (sun) assembly 4 as shown on FIG. 1. The balls are mounted on tiltable axles 5, themselves held in a carrier (stator, cage) assembly having a first carrier member 6 operably coupled to a second carrier member 7. The first carrier member 6 rotates with respect to the second carrier member 7, and vice versa. In some embodiments, the first carrier member 6 is fixed from rotation while the second carrier member 7 is configured to rotate with respect to the first carrier member, and vice versa. In one embodiment, the first carrier member 6 is provided with a number of radial guide slots 8. The second carrier member 7 is provided with a number of radially offset guide slots 9, as illustrated in FIG. 2. The radial guide slots 8 and the radially offset guide slots 9 are adapted to guide the tiltable axles 5. The axles 5 are adjusted to achieve a desired ratio of input speed to output speed during operation of the CVT. In some embodiments, adjustment of the axles 5 involves control of the position of the first and second carrier members to impart a tilting of the axles 5 and thereby adjusts the speed ratio of the variator. Other types of ball CVTs also exist, but are slightly different.

The working principle of such a CVP of FIG. 1 is shown on FIG. 3. The CVP itself works with a traction fluid. The lubricant between the ball and the conical rings acts as a solid at high pressure, transferring the power from the input ring, through the balls, to the output ring. By tilting the balls' axes, the ratio is changed between input and output. When the axis is horizontal the ratio is one, illustrated in FIG. 3, when the axis is tilted the distance between the axis and the contact point change, modifying the overall ratio. All the balls' axes are tilted at the same time with a mechanism included in the carrier and/or idler. Embodiments disclosed here are related to the control of a variator and/or a CVT using generally spherical planets each having a tiltable axis of rotation that are adjusted to achieve a desired ratio of input speed to output speed during operation. In some embodiments, adjustment of said axis of rotation involves angular misalignment of the planet axis in a first plane in order to achieve an angular adjustment of the planet axis in a second plane that is perpendicular to the first plane, thereby adjusting the speed ratio of the variator. The angular misalignment in the first plane is referred to here as "skew", "skew angle", and/or "skew condition". In one embodiment, a control system

coordinates the use of a skew angle to generate forces between certain contacting components in the variator that will tilt the planet axis of rotation. The tilting of the planet axis of rotation adjusts the speed ratio of the variator.

For description purposes, the term "radial" is used here to indicate a direction or position that is perpendicular relative to a longitudinal axis of a transmission or variator. The term "axial" as used here refers to a direction or position along an axis that is parallel to a main or longitudinal axis of a transmission or variator. For clarity and conciseness, at times similar components labeled similarly (for example, bearing 1011 A and bearing 1011 B) will be referred to collectively by a single label (for example, bearing 1011).

As used here, the terms "operationally connected," "operationally coupled", "operationally linked", "operably connected", "operably coupled", "operably linked," "operably coupleable" and like terms, refer to a relationship (mechanical, linkage, coupling, etc.) between elements whereby operation of one element results in a corresponding, following, or simultaneous operation or actuation of a second element. It is noted that in using said terms to describe inventive embodiments, specific structures or mechanisms that link or couple the elements are typically described. However, unless otherwise specifically stated, when one of said terms is used, the term indicates that the actual linkage or coupling take a variety of forms, which in certain instances will be readily apparent to a person of ordinary skill in the relevant technology.

It should be noted that reference herein to "traction" does not exclude applications where the dominant or exclusive mode of power transfer is through "friction." Without attempting to establish a categorical difference between traction and friction drives here, generally these are typically understood as different regimes of power transfer. Traction drives usually involve the transfer of power between two elements by shear forces in a thin fluid layer trapped between the elements. The fluids used in these applications usually exhibit traction coefficients greater than conventional mineral oils. The traction coefficient (μ) represents the maximum available traction force which would be available at the interfaces of the contacting components and is the ratio of the maximum available drive torque per contact force. Typically, friction drives generally relate to transferring power between two elements by frictional forces between the elements. For the purposes of this disclosure, it should be understood that the CVTs described here operate in both tractive and frictional applications. For example, in the embodiment where a CVT is used for a jDicycle application, the CVT operates at times as a friction drive and at other times as a traction drive, depending on the torque and speed conditions present during operation.

As used herein, "creep" or "slip" is the discrete local motion of a body relative to another and is exemplified by the relative velocities of rolling contact components such as the mechanism described herein. "Creep" is

characterized by the slowing of the output because the transmitted force is stretching the fluid film in the direction of rolling. As used herein, the term "ratio droop" refers to the shift of the tilt angle of the ball axis of rotation (sometimes referred to as the ratio angle or gamma angle) due to a compliance of an associated control linkage in proportion to a control force that is in proportion to transmitted torque, wherein the compliance of the control linkage corresponds to a change in the skew angle of the ball axis of rotation. As used herein, the term "load droop" refers to any operating event that reduces the ratio of output speed to input speed as transmitted torque increases.

Referring now to FIG. 4, in some embodiments, a continuously variable transmission (CVT) 10 is provided with a first rotatable shaft 1 1 adapted to receive power from a source of rotational power. In some embodiments, the first rotatable shaft 1 1 is operably coupled to a torque converter device, or other common coupling. The CVT 10 is provided with a variator (CVP) 12 aligned coaxially with the first rotatable shaft 1 1. In some embodiments, the variator 12 is similar to the variator depicted in FIGS. 1-3. The variator 12 includes a first traction ring assembly 13 and a second traction ring assembly 14 in contact with a number of balls. In some embodiments, the CVT 10 includes a planetary gear set 15 aligned coaxially with the first rotatable shaft 1 1 and the variator 12. The planetary gear set 15 includes a ring gear 16, a planet carrier 17, and a sun gear 18. In some embodiments, the planet carrier 17 is coupled to the first rotatable shaft 1 1. The ring gear 16 is coupled to the second traction ring assembly 14. In some embodiments, the CVT 10 has a first gear set 19 operably coupled to the first traction ring assembly 13. The first gear set 19 is configured to provide a power output path through a first coupling device 20. In some embodiments, the CVT 10 has a second gear set 21 operably coupled to the sun gear 18 and the first gear set 19. The second gear set 21 is configured to provide a power output path through a second coupling device 22. In some embodiments, the CVT 10 has a third gear set 23 operably coupled to the second traction ring assembly 14. The third gear set 21 is configured to provide a power output path through a third coupling device 24. It should be appreciated that the first coupling device 20, the second coupling device 22, and the third coupling device 23 are optionally configured by a designer to achieve desired performance and packaging of the continuously variable transmission.

Still referring to FIG. 4, in some embodiments; CVT 10 is provided with a locking clutch 25 operably coupled to the planet carrier 17 and the sun gear 18. The locking clutch 25 is arranged to selectively couple the planet carrier 17 and the sun gear 18 during operation of the CVT 10. In some embodiments, the locking clutch 25 is optionally configured as a wet clutch, a one-way clutch, a synchronous clutch, or a mechanical diode. In other embodiments, the locking clutch 25 is coupled to the planet carrier 17 and the ring gear 16. In yet other embodiments, the locking clutch 25 is coupled to the ring gear 16 and the sun gear 18.

Turning now to FIG. 5, in some embodiments a continuously variable transmission (CVT) 30 provided with a first rotatable shaft 31 adapted to receive power from a source of rotational power. In some embodiments, the first rotatable shaft 31 is operably coupled to a torque converter device, or other common coupling. The CVT 30 is provided with a variator (CVP) 32 aligned coaxially with the first rotatable shaft 31. In some embodiments, the variator 32 is similar to the variator depicted in FIGS. 1-3. The variator 32 includes a first traction ring assembly 33 and a second traction ring assembly 34 in contact with a number of balls. In some embodiments, the CVT 30 includes a planetary gear set 35 aligned coaxially with the first rotatable shaft 31 and the variator 32. The planetary gear set 35 includes a ring gear 36, a planet carrier 37, and a sun gear 38. In some embodiments, the planet carrier 17 is coupled to the first rotatable shaft 1 1. The ring gear 36 is coupled to the second traction ring assembly 34.

Still referring to FIG. 5, in some embodiments, the CVT 30 includes a first-and-third mode clutch 38 operably coupled to a second rotatable shaft 39. The second rotatable shaft 39 is coaxial with the first rotatable shaft 31 and forms a main axis of the CVT 30. The CVT 30 includes a second-and-fourth mode clutch 40 operably coupled to the second rotatable shaft 39. In some embodiments, the CVT 30 includes a first gear set 41 operably coupled to the first traction ring assembly 33. The first gear set 41 is coupled to a third rotatable shaft 42. The third rotatable shaft 42 is a parallel to the second rotatable shaft 39. In some embodiments, the CVT 30 includes a second gear set 43 operably coupled to the sun gear 38 and the third rotatable shaft 42. In some embodiments, the CVT 30 includes a third gear set 44 operably coupled to the second traction ring assembly 34 and a fourth rotatable shaft 45. The fourth rotatable shaft 45 is parallel to the second rotatable shaft 39 and the third rotatable shaft 42.

Still referring to FIG. 5, in some embodiments, the CVT 30 includes a first mode synchronizer clutch 46 positioned coaxially with, and coupled to, the fourth rotatable shaft 45. The first mode synchronizer clutch 46 is operably coupled to the first-and-third mode clutch 38 with a fourth gear set 47. In some embodiments, the CVT 30 includes a second mode synchronizer clutch 48 positioned coaxially with, and coupled to, the third rotatable shaft 42. The second mode synchronizer clutch 48 is operably coupled to the second-and- fourth mode clutch 40 with a fifth gear set 49. In some embodiments, the CVT 30 includes a third mode synchronizer clutch 50 positioned coaxially with, and coupled to, the fourth rotatable shaft 45. The third mode synchronizer clutch 50 is operably coupled to the first-and-third mode clutch 38 with a sixth gear set 51. In some embodiments, the CVT 30 includes a fourth mode synchronizer clutch 52 positioned coaxially with, and coupled to, the third rotatable shaft 42. The fourth mode synchronizer clutch 52 is operably coupled to the second-and- fourth mode clutch 40 with a seventh gear set 53. In some embodiments, the CVT 30 includes a reverse mode synchronizer clutch 54 positioned coaxially with, and coupled to the fourth rotatable shaft 45. The reverse mode

synchronizer clutch 54 is operably coupled to the second rotatable shaft 39 with a reverse gear set 55. In some embodiments, the CVT 30 includes a locking clutch 56 coupled to the planet carrier 37 and the ring gear 36.

Typically, synchronizer mechanisms (referred to herein as "synchronizer clutch") used in power transmissions include a dog clutch integrated with a speed-matching device such as a cone-clutch. During operation of the transmission, if the dog teeth of the dog clutch make contact with a gear, and the two parts are spinning at different speeds, the teeth will fail to engage and a loud grinding sound will be heard as they clatter together. For this reason, a synchronizer mechanism or synchronizer clutch is used, which consists of a cone clutch. Before the teeth engage, the cone clutch engages first, which brings the two rotating elements to the same speed using friction. Until synchronization occurs, the teeth are prevented from making contact. It should be appreciated that the exact design of the synchronizer clutch is within a designer's choice for satisfying packaging and performance requirements. A synchronizer clutch is optionally configured to be a two position clutch having an engaged position and a neutral (or free) position. A synchronizer clutch is optionally configured to be a three position clutch having a first engaged position, a second engaged position, and a neutral position. Embodiments disclosed herein use synchronizer clutches to enable the pre-selection of gear sets by a control system (not shown) for smooth transition between operating modes of the transmission. It should be appreciated that the powertrain configurations disclosed herein are optionally configured with other types of selectable torque transmitting devices including, and not limited to, wet clutches, dry clutches, dog clutches, and electromagnetic clutches, among j others.

Referring now to FIG. 6, during operation of the CVT 30 multiple modes of operation are achieved through engagement of the various clutching devices to provide modes corresponding to overlapping ranges of speed and torque.

Typically, the first mode of operation corresponds to a launch mode of a vehicle from a stop. The subsequent modes engaged correspond to higher speed ranges. Likewise, the reverse mode of operation corresponds to a reverse direction of a vehicle equipped with the CVT 30. The table depicted in FIG. 6, lists the modes of operation for the CVT 30 and indicates with an "x" the corresponding clutch engagement. For mode 1 operation, the first-and-third mode clutch 38 and the first synchronizer clutch 46 are engaged. For mode 2 operation, the second-and-fourth mode clutch 40 and the second synchronizer clutch 48 are engaged. For mode 3 operation, the first-and-third mode clutch 38 and the third synchronizer clutch 50 are engaged. For mode 4 operation, the second-and-fourth mode clutch 40 and the fourth synchronizer clutch 52 are engaged. For reverse mode operation, the reverse synchronizer clutch 54 is engaged. In some embodiments, the locking clutch 56 is selectively engaged during operation to provide a fixed ratio operating mode as an optional gear in any of the four modes of operation depicted in FIG. 6. During fixed ratio operating modes, power is transmitting through fixed gear ratios and the variator 32 operates at a 1 :1 speed ratio without transmitting any power. For example, engagement of the locking clutch 56 in mode 1 provides a fixed ratio for vehicle launch from a stop. The locking clutch 56 can be disengaged when a desired vehicle speed is reach and the vehicle continues to operate in mode 1 with power transmitted through the variator. The locking clutch 56 can be engaged during mode 2, mode 3, mode 4, or reverse operation to transmit power through fixed gear ratios and effectively bypass the variator 32.

Referring now to FIG. 7, in some embodiments; a powersplit variator 60 includes a first rotatable shaft 61 adapted to receive power from a source of rotational power (not shown). The powersplit variator 60 includes a second rotatable shaft 62 adapted to transmit a rotational power out of the powersplit variator 60. For example, the second rotatable shaft 62 is adapted to couple to a multiple speed gear box (not shown) to provide multiple modes of operation. In some embodiments, the second rotatable shaft 62 is adapted to couple to a fixed ratio automatic transmission such as the General Motors 4L60/4L80 transmission, the Ford Motor Company 4R70, and other well-known multiple speed automatic transmissions or simplified versions thereof utilizing

alternative friction plate clutches. It should be appreciated that embodiments of powersplit variators disclosed here are optionally configured to couple to any power transmission device. In some embodiments, the powersplit variator 60 includes a variator 63. The variator 63 is optionally configured to be a variator similar to the variator depicted in FIGS. 1-3. The variator 63 is provided with a first traction ring assembly 65 and a second traction ring assembly 64. In some embodiments, the powersplit variator 60 includes a planetary gear set 66 having a ring gear 67, a planet carrier 68, and a sun gear 69. The ring gear 67 is operably coupled to the second traction ring assembly 64. The sun gear 69 is operably coupled to the second rotatable shaft 62. In some embodiments, the second rotatable shaft 62 is coupled to the first traction ring assembly 65. In some embodiments, the powersplit variator 60 includes a locking clutch 70 operably coupled to the ring gear 67 and the planet carrier 68. It should be noted that in some embodiments, the first rotatable shaft 61 is adapted to transmit power out of the powersplit variator 60 and the second rotatable shaft 62 is adapted to operably couple to a source of rotational power.

Referring now to FIG. 8, in some embodiments; a powersplit variator 75 includes a first rotatable shaft 76 adapted to receive power from a source of rotational power (not shown). The powersplit variator 75 includes a second rotatable shaft 77 configured to transmit an output power from the powersplit variator 75. The powersplit variator 75 includes a variator 78 having a first traction ring assembly 80 and a second traction ring assembly 79. The powersplit variator 75 includes a planetary gear set 81 having a ring gear 82, a planet carrier 83, and a sun gear 84. In some embodiments, the ring gear 82 is operably coupled to the second traction ring assembly 79. The sun gear 84 is coupled to the second rotatable shaft 77. The first traction ring assembly 80 is coupled to the second rotatable shaft 77. In some embodiments, the powersplit variator 75 is provided with a locking clutch 85 coupled to the planet carrier 83 and the sun gear 84. It should be noted that in some embodiments, the first rotatable shaft 76 is adapted to transmit power out of the powersplit variator 75 and the second rotatable shaft 77 is adapted to operably couple to a source of rotational power.

Referring now to FIG. 9, in some embodiments; a powersplit variator 90 includes a first rotatable shaft 91 adapted to receive power from a source of rotational power (not shown). The powersplit variator 90 includes a second rotatable shaft 92 configured to transmit an output power from the powersplit variator 90. The powersplit variator 90 includes a variator 93 having a first traction ring assembly 95 and a second traction ring assembly 94. The powersplit variator 90 includes a planetary gear set 96 having a ring gear 97, a planet carrier 98, and a sun gear 99. In some embodiments, the ring gear 97 is operably coupled to the second traction ring assembly 94. The sun gear 99 is coupled to the second rotatable shaft 92. The first traction ring assembly 95 is coupled to the second rotatable shaft 92. In some embodiments, the powersplit variator 90 is provided with a locking clutch 100 coupled to the ring gear 97 and the sun gear 99. It should be noted that in some embodiments, the first rotatable shaft 91 is adapted to transmit power out of the powersplit variator 90 and the second rotatable shaft 92 is adapted to operably couple to a source of rotational power.

It should be appreciated that the locking clutch 25, the locking clutch 56, the locking clutch 70, the locking clutch 85, and the locking clutch 100 disclosed herein are optionally configured as wet clutch, dry clutches, synchronizer clutches, one-way clutches, or mechanical diodes.

Referring now to FIG. 10, in one embodiment, a transmission controller 101 includes an input signal processing module 102, a transmission control module 104 and an output signal processing module 106. The input signal processing module 102 is configured to receive a number of electronic signals from sensors provided on the vehicle and/or transmission. The sensors optionally include temperature sensors, speed sensors, position sensors, among others. In some embodiments, the signal processing module 102 optionally includes various sub-modules to perform routines such as signal acquisition, signal arbitration, or other known methods for signal processing. The output signal processing module 106 is optionally configured to

electronically communicate to a variety of actuators and sensors. In some embodiments, the output signal processing module 106 is configured to transmit commanded signals to actuators based on target values determined in the transmission control module 104. The transmission control module 104 optionally includes a variety of sub-modules or sub-routines for controlling continuously variable transmissions of the type discussed here. For example, the transmission control module 104 optionally includes a gear selection sub- module 107 and a clutch control sub-module 108 that are programmed to execute control over clutches or similar devices within the transmission. In some embodiments, the gear selection sub-module 107 is configured to coordinate selection of a desired gear ratio for the transmission. For example, the gear selection sub-module 107 is optionally configured to coordinate preselection of synchronizer clutches or other selectable torque transmitting devices. In some embodiments, the clutch control sub-module implements state machine control for the coordination of engagement of clutches or similar devices. The transmission control module 04 optionally includes a CVP control sub-module 110 programmed to execute a variety of measurements and determine target operating conditions of the CVP, for example, of the ball- type continuously variable transmissions and powersplit variators discussed here. It should be noted that the CVP control sub-module 1 0 optionally incorporates a number of sub-modules for performing measurements and control of the CVP. One sub-module included in the CVP control sub-module 110 is described herein.

Referring now to FIG. 11 , in some embodiments, the transmission controller 101 is configured to execute a control process 150 that begins at a start state 151 and proceeds to a block 152 where a number of signals are received. In some embodiments, the signals are indicative of a current CVP speed ratio, a vehicle speed, an accelerator pedal position, and a current transmission operating mode, and a variety of signals from sensors equipped in the multiple speed gear box, for example. The control process 150 proceeds to an evaluation block 153 where a request for fixed ratio operation is evaluated. During operation of vehicles equipped with continuously variable transmission having powersplit variators of the type disclosed herein, fixed ratio operation may be desired. For example, the transmission control system 101 monitors a number of signals and parameters relating to vehicle operation. Based at least in part on the signals and parameters of vehicle operation, the transmission control system 101 generates a signal indicative of a fixed ratio operation command. Vehicle operating conditions where fixed ratio operation is desirable include, but are not limited to vehicle launch from stop, low speed towing, high speed towing, low speed cruise (relatively constant speed) conditions, high speed cruise conditions, stepped shift operating conditions, limp home conditions, or cold temperature protection of the variator. The block 153 evaluates a command for fixed ratio operation. If the block 153 returns a false condition corresponding to a command to not operate in a fixed ratio, the control process 150 proceeds to a block 154 where commands are sent to continue to operate the transmission in a variable ratio mode. For example, operation in a variable ratio mode corresponds to the locking clutch 15, or similar locking clutches disclosed herein) to be disengaged and the variator speed ratio is under the control of the CVP control module 1 0. If the block 153 returns a positive condition corresponding to a command to operate in a fixed ratio mode, the control process 150 proceeds to the block 155 where a command is sent to engage the locking clutch, for example the locking clutch 25, among others. The control process 150 proceeds to a block 156 where a command is sent to disengage a CVP actuator.

In some embodiments, the CVP actuator is configured to couple to the variator 15, the variator 32, the variator 66, the variator 78, the variator 93, or any variator disclosed herein, to provide ratio control. In some embodiments, the CVP actuator is configured to couple to the carrier of the variator, for example the first carrier member 6. The CVP actuator is optionally configured to engage and disengage the first carrier member 6. Engagement of the CVP actuator corresponds to operation in a variable speed ratio mode where the CVP actuator positions the first carrier member 6 to achieve a desired speed ratio. Disengagement of the CVP actuator corresponds to a condition when the first carrier member 6 is not constrained by force or torque and the variator speed ratio is determined by the speed of the first traction ring assembly 2 and the second traction ring assembly 3, for example. It should be appreciated that the variator depicted in FIG. 1 is used as an illustrative example for the variators described herein. In some embodiments, the control process 150 proceeds back to the evaluation block 153.

Referring now to FIG. 2, in some embodiments, a variator 160 is provided with a first traction ring assembly 161 and a second traction ring assembly 162 in contact with a plurality of balls. The variator 160 is similar to the variator depicted in FIGS. 1-3. The first traction ring assembly 161 is coupled to a first rotatable shaft 163. In some embodiments, the first rotatable shaft 163 is adapted to operably couple to a source of rotational power. In other embodiments, the first rotatable shaft 163 is adapted to transmit a power out of the variator 160. The second traction ring assembly 162 is operably coupled to a second rotatable shaft 164. In some embodiments, the second rotatable shaft 164 is adapted to transmit a power out of the variator 160. In other embodiments, the second rotatable shaft 164 is adapted to operably couple to a source of rotational power. The variator 160 is provided with a locking clutch 165 coupled to the first traction ring assembly 161 and the second rotatable shaft 164. The locking clutch 165 is configured to selectively engage the first traction ring assembly 161 and the second rotatable shaft 164 to thereby transmit power from the first rotatable shaft 163 to the second rotatable shaft 164. Control of the locking clutch 165 is optionally provided by the control process 150. In some embodiments, the variator 160 is used in an electric vehicle (EV) to provide variable ratio operation between an electric motor and the driven wheels. For EV applications, the locking clutch 165 is engaged to bypass the CVP- at 1 :1 speed ratio and thus allow only underdrive through 1 :1 operation. The locking clutch 165 is connected between the first rotatable shaft 163 and the second rotatable shaft 164. A shift actuator (not shown) coupled to the variator 160 is adapted with a default position is towards 1 :1 speed ratio, and is configured to actively control the variator 160 towards underdrive for launch torque or regeneration optimization. The shift actuator is configured to passively disengage in all other operating speed ratios, and thereby reducing CVP losses. In some embodiments, the orientation of the locking clutch 165 is adapted to provide bypass of the CVP for underdrive conditions through 1 :1 speed ratio and thus provide only overdrive operation.

Referring now to FIG. 13, in some embodiments; a powersplit variator 170 includes a first rotatable shaft 171 adapted to receive power from a source of rotational power (not shown). The powersplit variator 170 includes a second rotatable shaft 172 configured to transmit an output power from the powersplit variator 170. The powersplit variator 170 includes a variator 173 having a first traction ring assembly 175 and a second traction ring assembly 174. The powersplit variator 170 includes a planetary gear set 176 having a ring gear 177, a planet carrier 178, and a sun gear 179. In some embodiments, the planetary gear set 176 is optionally configured with stepped planet gears supported in the planet carrier 178. The planet carrier 178 is operably coupled to the first rotatable shaft 171. In some embodiments, the ring gear 177 is operably coupled to the second traction ring assembly 174. The sun gear 179 is coupled to the second rotatable shaft 172. The first traction ring assembly 175 is coupled to the second rotatable shaft 172. In some embodiments, the powersplit variator 170 is provided with a first locking clutch 180 coupled to the ring gear 177 and to a grounded member of the transmission, such as a housing (not shown). The powersplit variator 170 includes a second locking clutch 181 operably coupled to the ring gear 177 and the second traction ring assembly 174. It should be noted that in some embodiments, the first rotatable shaft 171 is adapted to transmit power out of the powersplit variator 170 and the second rotatable shaft 172 is adapted to operably couple to a source of rotational power.

Turning to FIG. 14, during operation of the powersplit variator 170, engagement of the first locking clutch 80 corresponds to operation where power is transmitted from the first rotatable shaft 171 to the second rotatable shaft 172, or vice versa, without power transmission through the variator 173. This mode of operation is sometimes referred to herein as "bypass mode",

"CVP bypass", or "variator bypass". During operation of the powersplit variator 170, engagement of the second lock clutch 181 corresponds to operation where power is transmitted through the first rotatable shaft 171 to the variator 173 and the second rotatable shaft 172, or vice versa.

Referring now to FIG. 15, in some embodiments; a powersplit variator

185 includes a first rotatable shaft 186 adapted to receive power from a source of rotational power (not shown). The powersplit variator 185 includes a second rotatable shaft 187 configured to transmit an output power from the powersplit variator 185. The powersplit variator 185 includes a variator 188 having a first traction ring assembly 190 and a second traction ring assembly 189. The powersplit variator 185 includes a planetary gear set 191 having a ring gear 192, a planet carrier 193, and a sun gear 194. In some embodiments, the planetary gear set 191 is optionally configured with stepped planet gears supported in the planet carrier 193. The planet carrier 193 is operably coupled to the first rotatable shaft 186. In some embodiments, the ring gear 192 is operably coupled to the second rotatable shaft 87. The sun gear 194 is coupled to the second traction ring assembly 89. The first traction ring assembly 190 is coupled to the second rotatable shaft 187. In some

embodiments, the powersplit variator 185 is provided with a first locking clutch 195 coupled to the ring gear 192 and to a grounded member of the

transmissjon, such as a housing (not shown). The powersplit variator 185 includes a second locking clutch 196 operably coupled to the sun gear 194 and the second traction ring assembly 189. It should be noted that in some embodiments, the first rotatable shaft 186 is adapted to transmit power out of the powersplit variator 185 and the second rotatable shaft 187 is adapted to operably couple to a source of rotational power.

Turning to FIG. 16, during operation of the powersplit variator 187, engagement of the first locking clutch 195 corresponds to operation where power is transmitted from the first rotatable shaft 186 to the second rotatable shaft 187, or vice versa, without power transmission through the variator 188. This mode of operation is sometimes referred to herein as "bypass mode", "CVP bypass", or "variator bypass". During operation of the powersplit variator 185, engagement of the second lock clutch 196 corresponds to operation where power is transmitted through the first rotatable shaft 186 to the variator 188 and the second rotatable shaft 187, or vice versa.

Referring now to FIG. 17, in some embodiments; a powersplit variator 200 includes a first rotatable shaft 201 adapted to receive power from a source of rotational power (not shown). The powersplit variator 200 includes a second rotatable shaft 202 configured to transmit an output power from the powersplit variator 200. The powersplit variator 200 includes a variator 203 having a first traction ring assembly 205 and a second traction ring assembly 204. The powersplit variator 200 includes a planetary gear set 206 having a ring gear 207, a planet carrier 208, and a sun gear 209. The planet carrier 208 is operably coupled to the first rotatable shaft 201. In some embodiments, the ring gear 207 is operably coupled to the second traction ring assembly 204. The sun gear 209 is coupled to the second rotatable shaft 202. The first traction ring assembly 205 is coupled to the second rotatable shaft 202. In some embodiments, the powersplit variator 200 is provided with a first locking clutch 210 coupled to the ring gear 207 and to a grounded member of the transmission, such as a housing (not shown). The powersplit variator 200 includes a second locking clutch 211 operably coupled to the ring gear 207 and the second traction ring assembly 204. It should be noted that in some embodiments, the first rotatable shaft 201 is adapted to transmit power out of the powersplit variator 200 and the second rotatable shaft 202 is adapted to operably couple to a source of rotational power. Turning to FIG. 18, during operation of the powersplit variator 200, engagement of the first locking clutch 210 corresponds to operation where power is transmitted from the first rotatable shaft 201 to the second rotatable shaft 202, or vice versa, without power transmission through the variator 203. This mode of operation is sometimes referred to herein as "bypass mode",

"CVP bypass", or "variator bypass". During operation of the powersplit variator 200, engagement of the second lock clutch 21 1 corresponds to operation where power is transmitted through the first rotatable shaft 201 to the variator 203 and the second rotatable shaft 202, or vice versa.

Referring now to FIG. 19, in some embodiments, a powersplit variator

215 includes a first rotatable shaft 216 adapted to receive power from a source of rotational power (not shown). The powersplit variator 215 includes a second rotatable shaft 220 configured to transmit an output power from the powersplit variator 215. The powersplit variator 215 includes a variator 218 having a first traction ring assembly 219 and a second traction ring assembly 220. In some embodiments, the second traction ring assembly 220 is operably coupled to the second rotatable shaft 217. The powersplit variator 215 includes a first clutch

221 (labeled as "C1" in Figure 19) operably coupled to the first rotatable shaft 216. The first clutch 221 is operably coupled to the first traction ring assembly 219. The powersplit variator 215 includes a second clutch 222 (labeled as "C2" in Figure 19) operably coupled to the first rotatable shaft 216. The powersplit variator 215 includes a third clutch 223 (labeled "C3" in Figure 19) operably coupled to the first rotatable shaft 216. The powersplit variator 215 includes a torque splitting planetary 224 operably coupled to the first traction ring assembly 219 and the second rotatable shaft 217. In some embodiments, the torque splitting planetary 224 is a typical ball thrust bearing and includes a ball cage supporting a number of balls in contact with an inner race and an outer race. In some embodiments, the torque splitting planetary 224 is arranged with the outer race operably coupled to the first traction ring assembly 219 and the inner race operably coupled to the first clutch 221 , the second clutch 222, and the third clutch 223, respectively. In some embodiments, the second clutch

222 is operably coupled to the cage of the torque splitting planetary 224. In some embodiments, the first clutch 221 , the second clutch 222, and the third clutch 223 are hydraulically controlled clutches. In some embodiments, a spring element (not shown) is arranged between any of the clutches to provide a pre-load force.

Referring now to FIG. 20, during operably of the powersplit variator 215, engagement of the first clutch 221 and disengagement of the second clutch 222 and the third clutch 223 corresponds to a "CVT" mode of operation. In the CVT mode of operation, the first traction ring assembly 219 is engaged to the first rotatable shaft 216, and the powersplit variator 215 acts as a wide ratio continuously variable, non-inverting continuously variable planetary device with output at the second traction ring assembly 220. Engagement of the second clutch 222 and disengagement of the first clutch 221 and the third clutch 223 corresponds to a "torque split CVT" mode of operation. In the torque split CVT mode, the first rotatable shaft 216 is coupled to the cage of the torque splitting planetary 224 to thereby split the power input from the first rotatable shaft 216 to the variator 218 and the second rotatable shaft 217. Engagement of the third clutch 223 and disengagement of the first clutch 221 and the second clutch 222 corresponds to a CVP bypass mode of operation. In the CVP bypass mode, power is transmitted from the first rotatable shaft 216 to the second rotatable shaft 217 without passing through the variator 218.

Provided herein is a vehicle including the variable transmission of any one of the transmissions described herein.

Provided herein is a method including providing a variable transmission of any one of the transmissions described herein.

Provided herein is a method including providing a vehicle driveline of the kind described herein.

Provided herein is a method including providing a vehicle having any one of the transmission described herein.

It should be noted that the description above has provided dimensions for certain components or subassemblies. The mentioned dimensions, or ranges of dimensions, are provided in order to comply as best as possible with certain legal requirements, such as best mode. However, the scope of the embodiments described herein are to be determined solely by the language of the claims, and consequently, none of the mentioned dimensions is to be considered limiting on the inventive embodiments, except in so far as any one claim makes a specified dimension, or range of thereof, a feature of the claim.

While preferred embodiments have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the preferred embodiments. It should be understood that various alternatives to the embodiments described herein may be employed in practice. It is intended that the following claims define the scope of the preferred embodiments and that methods and structures within the scope of these claims and their equivalents be covered thereby.

Claims

WHAT IS CLAIMED IS:

1. A continuously variable transmission comprising:

a first rotatable shaft operably coupleable to a source of rotational power;

a second rotatable shaft arranged coaxially with the first rotatable shaft, the first rotatable shaft and the second rotatable shaft forming a main axis; a ball-type variator assembly having a first traction ring assembly and a second traction ring assembly in contact with a plurality of balls, wherein each ball of the plurality of balls has a tiltable axis of rotation, the variator assembly is coaxial with the main axis, the first traction ring is operably coupled to the second rotatable shaft;

a planetary gearset having a sun gear operably coupled to the first traction ring assembly, a planet carrier operably coupled to the first rotatable shaft, and a ring gear coupled to the second traction ring assembly; and

a locking clutch operably coupled to the planet carrier.

2. The continuously variable transmission of Claim 1 , wherein the locking clutch is coupled to the ring gear.

3. The continuously variable transmission of Claim 1 , wherein the locking clutch is coupled to the sun gear.

4. The continuously variable transmission of Claim 1 , wherein the second rotatable shaft is operably coupled to a multiple speed gear box having multiple operating modes.

5. The continuously variable transmission of Claim 1 , wherein the variator assembly is provided with an actuator configured to engage and disengage during operation.

6. A continuously variable transmission comprising:

a first rotatable shaft operably coupleable to a source of rotational power;

a locking clutch operably coupled to the ring gear and the sun gear.

7. The continuously variable transmission of Claim 6, wherein the second rotatable shaft is configured to operably couple to a multiple speed gear box having multiple operating modes.

8. A method of operating vehicle provided with a continuously variable transmission having a ball-type variator, the method comprising the steps of:

operating a powersplit variator comprising:

a first rotatable shaft operably coupleable to a source of rotational power;

a second rotatable shaft arranged coaxially with the first rotatable shaft, the first rotatable shaft and the second rotatable shaft forming a main axis;

a ball-type variator assembly having a first traction ring assembly and a second traction ring assembly in contact with a plurality of balls, wherein each ball of the plurality of balls has a tiltable axis of rotation, the variator assembly is coaxial with the main axis, the first traction ring is operably coupled to the second rotatable shaft; a planetary gearset having a sun gear operably coupled to the first traction ring assembly, a planet carrier operably coupled to the first rotatable shaft, and a ring gear coupled to the second traction ring assembly; and

a locking clutch coupled to the planetary gearset; evaluating a command for fixed ratio operation;

commanding an engagement of the locking clutch; and

commanding a disengagement of a variator actuator, the variator actuator coupled to the variator and configured to control a speed ratio of the variator.

9. The method of Claim 8, wherein commanding an engagement of the locking clutch further comprises engaging the ring gear and the planet carrier of the planetary gear set.

10. The method of Claim 8, wherein commanding an engagement of the locking clutch further comprises engaging the sun gear and the planet carrier of the planetary gear set.

11. The method of Claim 8, wherein commanding an engagement of the locking clutch further comprises engaging the ring gear and the sun gear of the planetary gear set.

12. The method of Claim 8, wherein evaluating a command for fixed ratio operation further comprises monitoring a plurality of signals indicative of a launch condition of the vehicle.

13. The method of Claim 8, wherein evaluating a command for a fixed ratio operation further comprises monitoring a plurality of signals indicative of a low speed cruise condition of the vehicle.

14. The method of Claim 8, wherein evaluating a command for a fixed ratio operation further comprises monitoring a plurality of signals indicative of a high speed cruise condition of the vehicle.

15. The method of Claim 8, wherein evaluating a command for a fixed ratio operation further comprises monitoring a plurality of signals indicative of a towing condition of the vehicle.

16. The method of Claim 8, wherein evaluating a command for a fixed ratio operation further comprises monitoring a plurality of signals indicative of a limp home mode of operation for the vehicle.

17. A continuously variable transmission comprising:

a first rotatable shaft;

a second rotatable shaft arranged coaxially with the first rotatable shaft, the first rotatable shaft and the second rotatable shaft forming a main axis, the second rotatable shaft operably coupled to a source of rotational power;

a ball-type variator assembly having a first traction ring assembly and a second traction ring assembly in contact with a plurality of balls, wherein each ball of the plurality of balls has a tiltable axis of rotation, the variator assembly is coaxial with the main axis, the first traction ring is operably coupled to the second rotatable shaft;

a locking clutch operably coupled to the planet carrier.

18. The continuously variable transmission of Claim 17, wherein the locking clutch is coupled to the ring gear.

19. The continuously variable transmission of Claim 17, wherein the locking clutch is coupled to the sun gear.

20. The continuously variable transmission of Claim 17, wherein the first rotatable shaft is operably coupled to a multiple speed gear box having multiple operating modes.

21. The continuously variable transmission of Claim 17, wherein the variator assembly is provided with an actuator configured to engage and disengage during operation.

22. A continuously variable transmission comprising:

a first rotatable shaft;

a second rotatable shaft arranged coaxially with the first rotatable shaft, the first rotatable shaft and the second rotatable shaft forming a main axis, the second rotatable shaft operably coupleable to a source of rotational power; a ball-type variator assembly having a first traction ring assembly and a second traction ring assembly in contact with a plurality of balls, wherein each ball of the plurality of balls has a tiltable axis of rotation, the variator assembly is coaxial with the main axis, the first traction ring is operably coupled to the second rotatable shaft;

a locking clutch operably coupled to the ring gear and the sun gear.

23. The continuously variable transmission of Claim 22, wherein the first rotatable shaft is configured to operably couple to a multiple speed gear box having multiple operating modes.

24. The continuously variable transmission of any of Claims 1 , 6, 17, or 22, wherein the variator comprises a traction fluid.

25. A vehicle driveline comprising: a power source, a variable transmission of any of Claims 1 , 6, 17, or 22 drivingly engaged with the power source, and a vehicle output drivingly engaged with the variable transmission.

26. The vehicle driveline of Claim 25, wherein the power source is drivingly engaged with the vehicle output.

27. A method of operating vehicle provided with a continuously variable transmission having a ball-type variator, the method comprising the steps of:

operating a powersplit variator comprising:

a first rotatable shaft operably coupleable to a source of rotational power;

a shift actuator operably coupled to the ball-type variator, the shift actuator configured to control a ratio of the ball-type variator, the shift actuator configured to engage and disengage the ball-type variator; a locking clutch coupled to the first rotatable shaft and the second rotatable shaft;

evaluating a command for fixed ratio operation;

commanding an engagement of the locking clutch; and

commanding a disengagement of the shift actuator.

28. The method of Claim 27, wherein commanding an engagement of the locking clutch further comprises coupling the first rotatable shaft to the second rotatable shaft and the sun gear of the planetary gear set.

29. The method of Claim 28, wherein evaluating a command for fixed ratio operation further comprises monitoring a plurality of signals indicative of a launch condition of the vehicle.

30. The method of Claim 28, wherein evaluating a command for a fixed ratio operation further comprises monitoring a plurality of signals indicative of a low speed cruise condition of the vehicle.

31. The method of Claim 28, wherein evaluating a command for fixed ratio operation further comprises monitoring a plurality of signals indicative of electric vehicle operation.

32. A continuously variable transmission comprising:

a first rotatable shaft;

a planetary gearset having a sun gear operably coupled to the first traction ring assembly, a planet carrier operably coupled to the first rotatable shaft, and a ring gear operably coupled to the second traction ring assembly; a first locking clutch operably coupled to the ring gear and a grounded member; and

a second locking clutch operably coupled the ring gear and the second traction ring assembly.

33. The continuously variable transmission of Claim 32 wherein the planetary gearset further comprising a plurality of stepped gears supported in the planet carrier.

34. A continuously variable transmission comprising: a first rotatable shaft;

a torque splitting planetary having an inner race in contact with a plurality of bails supported in a ball cage, an outer race in contact with the plurality of balls;

wherein the outer race is operably coupled to the first traction ring assembly, and the inner race is operably coupled to the second traction ring assembly;

a first clutch operably coupled to the first rotatable shaft and the first traction ring assembly;

a second clutch operably coupled to the first rotatable shaft and the ball cage; and

a third clutch operably coupled to the first rotatable shaft and the inner race.

35. The continuously variable transmission of Claim 34, wherein engagement of the first clutch, disengagement of the second clutch, and disengagement of the third clutch, corresponds to a CVT mode of operation, wherein a power is transmitted from the first rotatable shaft through the first traction ring assembly and out of the second traction ring assembly.

36. The continuously variable transmission of Claim 34, wherein engagement of the second clutch, disengagement of the first clutch, and disengagement of the third clutch, corresponds to a torque split CVT mode of operation, wherein a power is transmitted from the first rotatable shaft to the first traction ring assembly and to the second rotatable shaft.

37. The continuously variable transmission of Claim 34, wherein engagement of the third clutch, disengagement of the first clutch, and disengagement of the second clutch, corresponds to a bypass mode of operation, wherein a power is transmitted from the first rotatable shaft to the second rotatable shaft.