TRANSMISSION

CROSS-REFERENCES TO RELATED APPLICATIONS

[0001] The present application claims the benefit of U.S. Provisional Patent Application No. 61/819,440, filed May 3, 2013 which application is incorporated herein by reference.

BACKGROUND

[0002] Automatic and manual transmissions are commonly used on automobile vehicles. Those transmissions are becoming more and more complicated since the engine speed has to be more precisely controlled to limit the fuel consumption and the emissions of cars. This finer control of the engine speed in usual transmissions can only be done by adding more discrete step ratio gears and increasing the overall complexity and cost. Consequently, 6- speed manual transmissions then become more frequently used as are 8 or 9 speed automatic transmissions.

[0003] Transmissions can be used to vary the ratio of rotation an input shaft to an output shaft. This variation of input rotation to output rotation can provide increased performance and fuel economy. The transmission speed ratio of at least some prior transmission can be discrete, for example with fixed gear ratios, which can make switching gears less than desirable. Recently, continuously variable transmissions have been proposed to provide a continuously variable transition speed ratio.

SUMMARY

[0004] Provided herein is a variable transmission comprising an input shaft; a tilting ball variator comprising an input ring, an output ring, and a plurality of tilting variator balls, wherein the input ring is drivingly engaged with the input shaft; a double pinion planetary gearset comprising a second sun gear, a plurality of inner planet gears that engage a plurality of outer planet gears, wherein the inner planet gears and the outer planet gears are carried by a planet carrier (alternatively called second carrier), and a second ring gear (alternatively called second ring or second ring gear); a simple planetary gear set comprising a simple sun gear, a plurality of simple planet gears, a simple planet gear carrier, and a simple ring gear, wherein the simple sun gear is drivingly engaged by the output ring of the tilting ball variator, and the simple carrier is drivingly engaged with the second carrier; a direct mode clutch configured to selectively rotationally fix the simple carrier to the simple sun gear, thereby forcing the simple ring gear to rotate at the same speed as the simple sun gear; an overdrive clutch configured to selectively rotationally fix the input shaft to the second ring; an output shaft drivingly engaged by the simple ring gear of the simple planetary gear set. In some embodiments, the variable transmission comprises a direct drive mode, wherein disengagement of the overdrive clutch directs all power from the input shaft through the tilting ball variator and engagement of the direct mode clutch couples the output shaft to the tilting ball variator output through the simple planetary gearset, thereby matching an output of variable transmission to the output ring of the tilting ball variator. In some embodiments, the variable transmission comprises an overdrive mode, wherein disengagement of the direct mode clutch and engagement of the overdrive clutch redirects a portion of the input shaft power from the tilting ball variator to the simple carrier through the double pinion planetary gearset, thereby allowing increased output shaft speed relative to the direct drive mode when the tilting ball variator output is decreased. In some embodiments, the variable transmission comprises a reverse clutch, that selectively grounds the simple carrier; and a reverse mode wherein engagement of the reverse clutch and disengagement of the direct mode clutch and overdrive clutch directs input shaft power through the tilting ball variator and the simple sun gear, thereby allowing the output shaft to be driven by the simple ring gear in reverse. In some embodiments, the variable transmission is part of a motor vehicle powertrain. In some embodiments, the gear ratios of the internal components of the double pinion planetary gearset are chosen such the second ring gear spins at the same rate as the input shaft when the tilting ball variator operates at its maximum speed ratio, thereby allowing synchronous shifting between direct drive and overdrive modes. In some embodiments, the variable transmission comprises a forward range of output shaft speed ratios of 0.5 to 4.25. Provided herein is a variable transmission comprising: an input shaft; a tilting ball variator comprising an input ring, an output ring, and a plurality of tilting variator balls, wherein the input ring is drivingly engaged with the input shaft; a double pinion planetary gearset comprising a second sun gear, a plurality of inner planet gears that engage a plurality of outer planet gears, wherein the inner planet gears and the outer planet gears are carried by a planet carrier (alternatively called second carrier), and a ring gear (alternatively called second ring or second ring gear), wherein the second sun gear is grounded; a simple planetary gear set comprising a simple sun gear, a plurality of simple planet gears, a simple planet gear carrier rotatably coupled to the second carrier, and a simple ring gear rotatably coupled to the output ring of the tilting ball variator; a direct drive mode clutch that selectively rotatably fixes the simple sun gear to the simple carrier, thereby forcing the simple sun gear to rotate at the same speed as the simple ring gear; an overdrive clutch that selectively rotatably fixes the second ring gear to the input shaft; and an output shaft drivingly engaged by the simple sun gear. In some embodiments, the variable transmission comprises a direct drive mode wherein all input shaft power is directed through the tilting ball variator and engagement of the direct drive clutch directly couples the output shaft to the tilting ball variator output via the simple planetary gearset. In some embodiments, the variable transmission comprises an overdrive mode wherein engagement of the overdrive clutch shifts a portion of the input shaft power from the tilting ball variator to simple carrier through second ring gear and second planet carrier, thereby allowing the variable transmission to drive the output shaft at higher speeds relative to speeds achievable in the direct drive mode. In some embodiments, the variable transmission comprises a reverse mode clutch configured to selectively ground the simple carrier; and a reverse mode wherein engagement of the reverse mode clutch directs input shaft power through the simple ring gear and simple sun gear, thereby driving allowing the output shaft to be driven in reverse. In some embodiments, the gear ratios of the internal components of the double pinion planetary gearset are chosen such the second ring gear spins at the same rate as the input shaft when the tilting ball variator operates at its maximum speed ratio, thereby allowing synchronous shifting between direct drive and overdrive modes. In some embodiments, the variable transmission is part of a motor vehicle powertrain. In some embodiments, the variable transmission comprises a forward range of output shaft speed ratios of 0.5 to 4.25. Provided herein is a variable transmission comprising: an input shaft; a tilting ball variator comprising an input ring, an output ring, and a plurality of tilting variator balls, wherein the input ring is drivingly engaged with the input shaft; a double pinion planetary gearset comprising a second sun gear, a plurality of inner planet gears that engage a plurality of outer planet gears, wherein the inner planet gears and the outer planet gears are carried by a planet carrier (alternatively called second carrier), and a ring gear

(alternatively called second ring or second ring gear), wherein the planet carrier is grounded and the second sun gear is drivingly engaged by the output ring of the tilting ball variator, thereby creating an underdriven variator output at the second ring gear; a simple planetary gear set comprising a simple sun gear, a plurality of simple planet gears, a simple planet gear carrier, and a simple ring gear rotatably coupled to the second ring gear; and an output shaft drivingly engaged by the simple sun gear. In some embodiments, the variable transmission comprises a direct drive clutch configured to selectively rotatably fix the simple carrier to the simple sun gear; a direct drive mode wherein all input shaft power flows through the tilting ball variator and wherein engagement of the direct drive clutch directly couples the output shaft to the

underdriven variator output via the simple planetary gearset. In some embodiments, the variable transmission comprises an overdrive clutch configured to selectively rotatably fix the simple carrier to the input shaft; and an overdrive mode wherein engagement of the overdrive clutch shifts a portion of the input shaft power from the tilting ball variator to the simple carrier, thereby allowing the variable transmission to drive the output shaft at higher speeds relative to speeds achievable in the direct drive mode. In some embodiments, the variable transmission comprises a reverse clutch configured to selectively ground the simple carrier; and a reverse mode, wherein the under driven variator output drives the output shaft in reverse via the simple planetary gearset. In some embodiments, the gear ratios of the internal components of the simple planetary gearset are chosen such the simple planetary gear carrier spins at the same rate as the input shaft when the tilting ball variator operates at its maximum speed ratio, thereby allowing synchronous shifting between direct drive and overdrive modes. In some embodiments, the variable transmission is part of a motor vehicle powertrain. In some embodiments, the variable transmission comprises a forward range of output shaft speed ratios of 0.25 to 2.125.

INCORPORATION BY REFERENCE

[0005] 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

[0006] The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative

embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which:

[0007] Figure 1 is a side sectional view of a ball-type variator;

[0008] Figure 2 is a magnified, side sectional view of a ball of a variator of Figure 1 having a symmetric arrangement of a first ring assembly and a second ring assembly;

[0009] Figure 3 is a block diagram of a continuously variable transmission (CVT) used in an automobile;

[0010] Figure 4 A shows a speed diagram representing the speeds of the planetary: the X axis representing the speed of the relevant component and the three Y axes representing the sun, carrier and ring components, in accordance with embodiments described herein, and in accordance with an embodiment of the Dual Mode CVT 6.0 OAR as described herein and shown in Figure 4B;

[0011] Figure 4B shows an embodiment of the Dual Mode CVT 6.0 OAR as described herein; [0012] Figure 5A shows a speed diagram representing the speeds of the planetary: the X axis representing the speed of the relevant component and the three Y axes representing the sun, carrier and ring components, in accordance with embodiments described herein, and in accordance with an embodiment of the Dual Mode CVT 8.0 OAR as described herein and shown in Figure 5B;

[0013] Figure 5B shows an embodiment of the Dual Mode CVT 8.0 OAR as described herein;

[0014] Figure 6A shows a speed diagram representing the speeds of the planetary: the X axis representing the speed of the relevant component and the three Y axes representing the sun, carrier and ring components, in accordance with embodiments described herein, and in accordance with an embodiment of the Underdriven Dual Mode CVT 8.5 OAR as described herein and shown in Figure 6B;

[0015] Figure 6B shows an embodiment of the Underdriven Dual Mode CVT 8.5 OAR as described herein;

[0016] Figure 6C shows a plot of transmission ratio (X-axis) vs. CVT efficiency (Y-axis), wherein the speed ratio is the inverse of torque ratio of Underdriven Dual Mode CVT 8.5 OAR of Figure 6 A and Figure 6B.

DETAILED DESCRIPTION

[0017] The continuously variable transmission speed ratio can have the advantage of providing a smoother and continuous transition from a low speed ratio to a high speed ratio. However, the prior continuously variable transmissions can be more complex than would be ideal.

[0018] Continuously Variable Transmissions or CVTs are of many types: belts with variable pulleys, toroidal, and conical, for non-limiting example. The principle of a CVT is that it enables the engine to run at its most efficient rotation speed by changing steplessly the transmission ratio in function of the speed of the car and the torque demand (throttle position) of the driver. If needed for example when accelerating, the CVT is configured to also shift to the most optimum ratio providing more power. A CVT is configured to change the ratio from the minimum to the maximum ratio without any interruption of the power transmission, as opposed to the opposite of usual transmissions which require an interruption of the power transmission by disengaging to shift from one discrete ratio to engage the next ratio.

[0019] A specific use of CVTs is the Infinite Variable Transmission or IVT. Where the CVT is limited to positive speed ratios, the IVT configuration is configured to perform a neutral gear and even reverse ratios steplessly. In some embodiments, a CVT is used as an IVT in some drive line configurations. [0020] Provided herein are configurations of CVTs based on a ball type variators, also known as CVP, for constant variable planetary. Some general aspects of the CVTs and CVPs are described in US20040616399 or AU2011224083A1, incorporated herein by reference in their entirety. The type of CVT provided herein comprises a variator 2 comprising a plurality of variator balls 8a, 8b, depending on the application, two discs or annular rings (input ring 4, output ring 6) each having an engagement portion 10, 12 that engages the variator balls 8a, 8b, at least. The engagement portions 10, 12 are optionally in a conical or toroidal convex or concave surface contact with the variator balls 8a, 8b, as input and output. The variator optionally includes an idler contacting the balls as well as shown on FIG. 1. The variator balls 8a, 8b are mounted on axes, themselves held in a cage or carrier allowing changing the ratio by tilting the variator balls' axes. Other types of ball CVTs also exist, like the one produced by Milner but are slightly different. These alternative ball CVTs are additionally contemplated herein. The working principle generally speaking, of a ball-type variator (i.e. CVP) of a CVT is shown in FIG. 2.

[0021] As shown in FIG.l, a variator is a system that uses a set of rotating and tilting balls in a carrier that is positioned between an input ring and an output ring. Tilting the balls changes their contact diameters and varies the speed ratio. As a result, the variator system offers continuous transition to any ratio within its range. The gear ratio is shifted by tilting the axes of the spheres in a continuous fashion, to provide different contact radii, which in turn drive the input and output rings, or discs.

[0022] The variator, as noted above, has multiple balls to transfer torque through multiple fluid patches. The balls are placed in a circular array around a central idler (sun) and contact separate the input and output traction rings. This configuration allows the input and output to be concentric and compact. The result is the ability to sweep the transmission through the entire ratio range smoothly, while in motion, under load, or stopped.

[0023] A traction fluid is optionally located in the variator for lubrication and traction. When this fluid undergoes high contact pressures under rolling contact between the two very hard elements, the balls and the rings, the fluid undergoes a near-instantaneous phase transition to an elastic solid. Within this patch of traction the molecules of the fluid stack up and link to form a solid, through which shear force and thus torque can be transferred. Note that the rolling elements are actually not in physical contact when the elements are rotating.

[0024] The variator 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 first ring assembly (input of the variator), through the variator balls, to the second ring assembly (output of the variator). By tilting the variator balls' axes, the ratio is changed between input and output. When the axis of each of the variator balls is horizontal the ratio is one, when the axis is tilted the distance between the axis and the contact point change, modifying the overall ratio. All the variator balls 'axles are tilted at the same time and same angle with a mechanism included in the cage.

[0025] In a vehicle, the CVT is used to replace traditional transmission and is located between the engine (ICE or internal combustion engine) and the differential as shown on FIG. 3. A torsional dampener (alternatively called a damper) is optionally introduced between the engine and the CVT to avoid transferring torque peaks and vibrations that could damage the CVT. In some configurations this dampener is coupled with a clutch for the starting function or for allowing the engine to be decoupled from the transmission. In some embodiments, the clutch is located at a different place in the driveline for allowing an interruption in the transmission of power in the driveline.

[0026] The embodiments of the present invention as described herein will find many

applications. For example, although reference is made to vehicular applications, the

continuously variable transmission as described herein can be used in many applications such as bicycles, motorized vehicles and power tools, for example.

[0027] Provided herein are embodiments of variable transmission configurations that include a variator 2 (alternatively called a CVP herein, such as a tilting-ball type variator), a simple planetary gearset 26 (alternatively called a first planetary gearset herein), a double pinion planetary gearset 36 (wherein the double pinion refers to two sets of planets, i.e. inner planets 42a, 42b, and outer planets 44a, and 44b that are included in the double pinion planetary gearset 36; the double pinion planetary gearset 36 is alternatively called a second planetary gearset herein), a reverse clutch 48, a direct mode clutch 50, and an overdrive clutch 52. The embodiments depicted, and obvious variants to one of skill in the art upon reviewing the disclosure herein, provide a dual mode of operation (i.e. a low mode or direct drive mode), and a high mode of operation (i.e. overdrive), at least, as well as a reverse mode. In each embodiment, selective engagement of the reverse drive 48 clutch and/or the direct mode clutch act 50 as starting clutches for the transmission. Furthermore, an embodiment is depicted herein that provides, additionally or alternatively, an under-drive mode of operation (see FIGs. 6A, 6B, and 6C).

[0028] The embodiments of the variable transmissions provided herein comprise a variator 2 that functions in a direct mode (100% of the power goes through the variator) in the low mode and allows the power in the variator 2 to be reduced dramatically in the high mode (power in the variator will be decrease from approximately 90% at the synchronous point to 15% at maximum overdrive). In addition to the reduction of power in the variator 2, the low-high mode shift is synchronous in that all internal components of the transmission are spinning at the same speed before, during, and after the synchronous shift. This allows a high quality mode shift to be executed by simply applying the on-coming clutch prior to releasing the off-going clutch. Thus, each of the embodiment transmissions herein are considered Dual Mode transmissions or Dual Mode CVTs having synchronous shifting capability and using a tilting ball -type variator 2 as described herein. The clutch arrangements and gear arrangements described and provided herein provide unexpected and superior benefits to the transmission with regard to fuel economy and seamless shifting over a wider overall ratio, as noted herein. The tilting ball variator 2 is alternatively or additionally described as a co-axial device that operates between an under-drive ratio of one over the square root of the overall ratio of the variator 2 to an overdrive ratio of the square root of the overall ratio of the variator 2. Additionally, the reverse ratio is achieved by grounding the center node of the summing differential rather than adding a dedicated reverse gearset or using the geared neutral mode.

[0029] The reduced fraction of power through the variator 2 in the high mode will significantly improve the fuel economy over a transmission that forces all of the power through the variator (as in the direct mode). Additionally, the synchronous shift will allow a "seamless" low-high mode shift that will feel like a single mode CVT with a significantly wider overall ratio (failing to provide the increased overall ratio of the high mode will reduce the potential fuel economy advantage of this CVT). A multi-mode synchronous shifting arrangement of components utilizing the specific arrangement of gears and clutches to adjust for using the tilting ball -type variator 2 is thus provided herein, along with reverse clutch 48 grounding the center node of the summing differential to also accommodate the tilting ball-type variator 2.

[0030] Provided herein is a variable transmission comprising an input shaft 14; a tilting ball variator 2 comprising an input ring 4, an output ring 6, and a plurality of tilting variator balls 8a, 8b, wherein the input ring 4 is drivingly engaged with the input shaft 14; a double pinion planetary gearset 36 comprising a second sun gear 38, a plurality of inner planet gears 42a, 42a that engage a plurality of outer planet gears 44a, 44b, wherein the inner planet gears and the outer planet gears are carried by a planet carrier 46 (alternatively called second carrier), and a second ring gear 40 (alternatively called second ring or second ring gear); a simple planetary gear set 26 comprising a simple sun gear 28, a plurality of simple planet gears 32a, 32b, a simple planet gear carrier 34, and a simple ring gear 30, wherein the simple sun gear 28 is drivingly engaged by the output ring 6 of the tilting ball variator 2, and the simple carrier 34 is drivingly engaged with the second carrier 46; a direct mode clutch 50 configured to selectively rotationally fix the simple carrier 34 to the simple sun gear 28, thereby forcing the simple ring gear 30 to rotate at the same speed as the simple sun gear 28; an overdrive clutch 52 configured to selectively rotationally fix the input shaft 14 to the second ring 40; an output shaft 16 drivingly engaged by the simple ring gear 30 of the simple planetary gear set 26.

[0031] In some embodiments, the variable transmission comprises a direct drive mode, wherein disengagement of the overdrive clutch directs all power from the input shaft through the tilting ball variator and engagement of the direct mode clutch couples the output shaft to the tilting ball variator output through the simple planetary gearset, thereby matching an output of variable transmission to the output ring of the tilting ball variator.

[0032] In some embodiments, the variable transmission comprises an overdrive mode, wherein disengagement of the direct mode clutch and engagement of the overdrive clutch redirects a portion of the input shaft power from the tilting ball variator to the simple carrier through the double pinion planetary gearset, thereby allowing the variable transmission to drive the output shaft at higher speeds relative to speeds achievable in the direct drive mode.

[0033] In some embodiments, the variable transmission comprises a reverse clutch, that selectively grounds the simple carrier; and a reverse mode wherein engagement of the reverse clutch and disengagement of the direct mode clutch and overdrive clutch directs input shaft power through the tilting ball variator and the simple sun gear, thereby allowing the output shaft to be driven by the simple ring gear in reverse.

[0034] In some embodiments, the variable transmission is part of a motor vehicle powertrain.

[0035] In some embodiments, the gear ratios of the internal components of the double pinion planetary gearset 36 are chosen such the second ring gear 40 spins at the same rate as the input shaft 14 when the tilting ball variator 2 operates at its maximum speed ratio, thereby allowing synchronous shifting between direct drive and overdrive modes.

[0036] In some embodiments, the variable transmission comprises a forward range of output shaft speed ratios of 0.5 to 4.25.

[0037] Provided herein is a variable transmission comprising: an input shaft 14; a tilting ball variator 2 comprising an input ring 4, an output ring 6, and a plurality of tilting variator balls 8a, 8b, wherein the input ring 4 is drivingly engaged with the input shaft 14; a double pinion planetary gearset 36 comprising a second sun gear 38, a plurality of inner planet gears 42a, 42a that engage a plurality of outer planet gears 44a, 44b, wherein the inner planet gears and the outer planet gears are carried by a planet carrier 46 (alternatively called second carrier), and a second ring gear 40 (alternatively called second ring or second ring gear), wherein the second sun gear 38 is grounded; a simple planetary gear set 26 comprising a simple sun gear 28, a plurality of simple planet gears 32a, 32b, a simple planet gear carrier 34 rotatably coupled to the second carrier 46, and a simple ring gear 30 rotatably coupled to the output ring 6 of the tilting ball variator 2; a direct drive mode clutch 50 that selectively rotatably fixes the simple sun gear 28 to the simple carrier 34, thereby forcing the simple sun gear 28 to rotate at the same speed as the simple ring gear 30; an overdrive clutch 52 that selectively rotatably fixes the second ring gear 40 to the input shaft 14; and an output shaft 16 drivingly engaged by the simple sun gear 28.

[0038] In some embodiments, the variable transmission comprises a direct drive mode wherein all input shaft power is directed through the tilting ball variator and engagement of the direct drive clutch directly couples the output shaft to the tilting ball variator output via the simple planetary gearset.

[0039] In some embodiments, the variable transmission comprises an overdrive mode wherein engagement of the overdrive clutch shifts a portion of the input shaft power from the tilting ball variator to simple carrier through second ring gear and second planet carrier, thereby allowing the variable transmission to drive the output shaft at higher speeds relative to speeds achievable in the direct drive mode.

[0040] In some embodiments, the variable transmission comprises a reverse mode clutch configured to selectively ground the simple carrier; and a reverse mode wherein engagement of the reverse mode clutch directs input shaft power through the simple ring gear and simple sun gear, thereby driving allowing the output shaft to be driven in reverse.

[0041] In some embodiments, the gear ratios of the internal components of the double pinion planetary gearset 36 are chosen such the second ring gear 40 spins at the same rate as the input shaft 14 when the tilting ball variator 2 operates at its maximum speed ratio, thereby allowing synchronous shifting between direct drive and overdrive modes.

[0042] In some embodiments, the variable transmission is part of a motor vehicle powertrain.

[0043] In some embodiments, the variable transmission comprises a forward range of output shaft speed ratios of 0.5 to 4, or 0.5 to 4.25.

[0044] Provided herein is a variable transmission comprising: an input shaft 14; a tilting ball variator 2 comprising an input ring 4, an output ring 6, and a plurality of tilting variator balls 8a, 8b, wherein the input ring 4 is drivingly engaged with the input shaft 14; a double pinion planetary gearset 36 comprising a second sun gear 38, a plurality of inner planet gears 42a, 42a that engage a plurality of outer planet gears 44a, 44b, wherein the inner planet gears and the outer planet gears are carried by a planet carrier 46 (alternatively called second carrier), and a second ring gear 40 (alternatively called second ring or second ring gear), wherein the planet carrier 46 is grounded and the second sun gear 38 is drivingly engaged by the output ring 6 of the tilting ball variator 2, thereby creating an underdriven variator output at the second ring gear 40; a simple planetary gear set 26 comprising a simple sun gear 28, a plurality of simple planet gears 32a, 32b, a simple planet gear carrier 34, and a simple ring gear 30 rotatably coupled to the second ring gear 40; and an output shaft 16 drivingly engaged by the simple sun gear 28.

[0045] In some embodiments, the variable transmission comprises a direct drive clutch 50 configured to selectively rotatably fix the simple carrier to the simple sun gear; a direct drive mode wherein all input shaft power flows through the tilting ball variator and wherein engagement of the direct drive clutch directly couples the output shaft to the underdriven variator output via the simple planetary gearset.

[0046] In some embodiments, the variable transmission comprises an overdrive clutch 52 configured to selectively rotatably fix the simple carrier to the input shaft; and an overdrive mode wherein engagement of the overdrive clutch shifts a portion of the input shaft power from the tilting ball variator to the simple carrier, thereby allowing the variable transmission to drive the output shaft at higher speeds relative to speeds achievable in the direct drive mode.

[0047] In some embodiments, the variable transmission comprises a reverse clutch 48 configured to selectively ground the simple carrier; and a reverse mode, wherein the under driven variator output drives the output shaft in reverse via the simple planetary gearset.

[0048] In some embodiments, the gear ratios of the internal components of the simple planetary gearset 26 are chosen such the simple planetary gear carrier 34 spins at the same rate as the input shaft 14 when the tilting ball variator 2 operates at its maximum speed ratio, thereby allowing synchronous shifting between direct drive and overdrive modes.

[0049] In some embodiments, the variable transmission is part of a motor vehicle powertrain.

[0050] In some embodiments, the variable transmission comprises a forward range of output shaft speed ratios of 0.25 to 2.125.

Example 1: Dual Mode CVT 6.0 OAR

[0051] Provided herein are embodiments of variable transmission configurations that include a variator 2 (alternatively called a CVP herein, such as a tilting-ball type variator), a simple planetary gearset 26 (alternatively called a first planetary gearset herein), a double pinion planetary gearset 36 (wherein the double pinion refers to two sets of planets, i.e. inner planets 42a, 42b, and outer planets 44a, and 44b that are included in the double pinion planetary gearset 36; the double pinion planetary gearset 36 is alternatively called a second planetary gearset herein), a reverse clutch 48, a direct mode clutch 50, and an overdrive clutch 52. The embodiments depicted, and obvious variants to one of skill in the art upon reviewing the disclosure herein, provide a dual mode of operation (i.e. a low mode or direct drive mode), and a high mode of operation (i.e. overdrive), at least, as well as a reverse mode. In each embodiment, selective engagement of the reverse drive clutch 48 and/or the direct mode clutch 50 act as starting clutches for the transmission. This embodiment variable transmission is referred to herein as a Dual Mode CVT having a 6.0 OAR ("OAR" stands for overall ratio).

[0052] The simple planetary gearset 26 of FIG. 4B comprises a sun 28 (also called a simple sun, which is named this since it is a component of the simple planetary gearset thus distinguishing it from the second sun, and not necessarily because it has any simple feature or function), a ring 30 (also called a simple ring, which is named this since it is a component of the simple planetary gearset thus distinguishing it from the second ring, and not necessarily because it has any simple feature or function), a plurality of planets 32a, 32b (also called simple planets, which are named this since they are components of the simple planetary gearset thus distinguishing them from the inner and outer planets, and not necessarily because they have any simple feature or function) forming a set of planets, and a carrier 34 (also called a simple carrier, which is named this since it is a component of the simple planetary gearset thus distinguishing it from the second carrier, and not necessarily because it has any simple feature or function). The double pinion planetary gearset 36 of FIG. 4B comprises a sun 38 (also called a second sun, which is named this since it is a component of the double pinion planetary gearset which is also called the second planetary gearset thus distinguishing it from the simple sun, and not necessarily because it has any secondary feature or function), a ring 40 (also called a second ring, which is named this since it is a component of the double pinion planetary gearset which is also called the second planetary gearset thus distinguishing it from the simple ring, and not necessarily because it has any secondary feature or function), a plurality of inner planets 42a, 42b forming a set of inner planets that engage the second sun 38 but do not engage the second ring 40, a plurality of outer planets 44a, 44b forming a set of outer planets each of which engages the second ring 40 and engages one of the inner planets 42a, 42b, and a carrier 46 (also called a second carrier, which is named this since it is a component of the double pinion planetary gearset which is also called the second planetary gearset thus distinguishing it from the simple carrier, and not necessarily because it has any secondary feature or function) of the inner planets 44a, 44b and inner planets 42a, 42b.

[0053] The three horizontal axes of FIG. 4 A represent respectively, from the bottom to the top, the simple sun 28 rotation speed ratio of the simple planetary gearset of FIG. 4B, the simple carrier 34 rotation speed ratio of the simple planetary gearset of FIG. 4B, and the simple ring 30 rotation speed ratio of the simple planetary gearset of FIG. 4B. In direct mode (under drive) with the direct mode clutch 50 engaged and the overdrive clutch 52 disengaged. The input shaft 14 power is completely directed through the ball variator 2. The direct mode clutch 50 connects the simple sun 28 and simple carrier 34 of the simple planetary gearset 26 together, such that the variator output ring 6 drives both the simple sun 28 and the simple carrier 34 at the same speed ratio. Thus in the underdrive mode the CVT output ring 6 (at the output ring) matches the variator speed ratio at the simple sun 28. The simple planetary carrier 34 is connected to the second planetary carrier 46. The second sun 38 is grounded. The second sun 38, planets, and second ring 40 gear ratios of the double pinion planetary set 36 are chosen such that, at the maximal variator speed ratio (2.0) the second ring 40 of the double pinion planetary gearset 36 has a rotating speed that matches the input shaft 14. At this point a synchronous shift to overdrive mode is possible wherein the overdrive clutch 52 is engaged and the direct drive clutch 50 is disengaged. In the overdrive mode input shaft 14 power is channeled both through the variator 2 and through both the double pinion planetary gearset 36 and the simple planetary gearset 26. The input shaft 14 power is still connected to the simple sun 28 via the variator 2, but now is also connected via the overdrive clutch 52 to the second ring 40 of the double pinion planetary gearset 36 which in turn drives the simple carrier 34 via the second carrier 46. In overdrive mode, lowering the variator speed ratio increases the differential in speed ratio between the simple sun 28 and simple carrier 34; the simple sun 28 will have a lower speed ratio than the simple carrier 34 causing an increase in the speed ratio of the simple ring 30 and output shaft 16 i.e. CVT OUT. This will also cause more power to flow through the mechanical path and less power to flow through the variator 2 resulting in increased efficiency. In reverse mode the simple carrier 34 is grounded via the reverse clutch 48, thus the output at the simple ring 30 is at a negative speed ratio of the variator output 6 (simple sun 28).

[0054] FIG. 4B depicts the arrangement and connections of the variator 2, simple planetary gearset 26, double pinion planetary gearset 36 and various clutches 48, 50, 52. The input shaft 14 is connected to the input ring 4 of the variator 2 and to the overdrive clutch 52 which will selectively connect the input shaft 14 to the second ring 40. The output ring 6 of the variator 2 is connected to the simple sun (SS) 28 and optionally to the simple carrier 34 via the direct mode clutch 50. The simple carrier 34 may be optionally grounded by the reverse clutch 48 for reverse mode operation. The simple carrier 34 is also connected to the second carrier 46. The second sun 38 is grounded in underdrive or direct mode. The direct mode clutch 50 engages the simple carrier 34 to the simple sun 28 which is connected in turn to the variator output ring 6. Thus the variator output ring 6 is effectively rigidly connected to the simple ring 30 and all input shaft power flows through the variator 2. At maximal variator speed ratio the second ring 40 is at the same speed as the input shaft so a synchronous mode shift to overdrive can be

accomplished by engaging the overdrive clutch 52 and disengaging the direct mode clutch 50. In overdrive the simple sun 28 is still driven by the variator output ring 6 but the simple carrier 34 is connected to the second carrier 46. In overdrive the simple carrier 34 will maintain the second carrier 46 speed but the variator 2 can lower the simple sun 28 speed thus increasing the simple ring 30 speed and speed of the output shaft 16. As shown in FIG 4B, the gear ratio (R/S) of the simple planetary gearset 26 of simple ring to simple sun is 1.5. Also as shown in FIG 4B, the gear ratio (R/S) of the double pinion planetary gearset 36 of second ring to second sun is 2.0

[0055] Table 1 below shows the clutch engagement scenarios of the embodiment transmission of FIG. 4B which result in the various modes of operation, i.e. direct drive mode (low mode), reverse mode, and overdrive mode (OD).

Table 1.

Example 2 Dual Mode CVT 8.0 OAR

[0056] Provided herein are embodiments of variable transmission configurations that include a variator 2 (alternatively called a CVP herein, such as a tilting-ball type variator), a simple planetary gearset 26, a double pinion planetary gearset 36, a reverse clutch 48, a direct mode clutch 50, and an overdrive clutch 52. The embodiments depicted, and obvious variants to one of skill in the art upon reviewing the disclosure herein, provide a dual mode of operation (i.e. a low mode or direct drive mode), and a high mode of operation (i.e. overdrive), at least, as well as a reverse mode. In each embodiment, selective engagement of the reverse clutch 48 and/or the direct mode clutch 50 act as starting clutches for the transmission. This embodiment variable transmission is referred to herein as a Dual Mode CVT having a 8.0 OAR ("OAR" stands for overall ratio).

[0057] The simple planetary gearset 26 of FIG. 5B comprises a sun 28 (also called a simple sun, which is named this since it is a component of the simple planetary gearset thus distinguishing it from the second sun, and not necessarily because it has any simple feature or function), a ring 30 (also called a simple ring, which is named this since it is a component of the simple planetary gearset thus distinguishing it from the second ring, and not necessarily because it has any simple feature or function), a plurality of planets 32a, 32b (also called a simple planets, which are named this since they are components of the simple planetary gearset thus distinguishing them from the inner and outer planets, and not necessarily because they have any simple feature or function) forming a set of planets, and a carrier 34 (also called a simple carrier, which is named this since it is a component of the simple planetary gearset thus distinguishing it from the second carrier, and not necessarily because it has any simple feature or function). The double pinion planetary gearset 36 of FIG. 5B comprises a sun 38 (also called a second sun, which is named this since it is a component of the double pinion planetary gearset which is also called the second planetary gearset thus distinguishing it from the simple sun, and not necessarily because it has any secondary feature or function), a ring 40 (also called a second ring, which is named this since it is a component of the double pinion planetary gearset which is also called the second planetary gearset thus distinguishing it from the simple ring, and not necessarily because it has any secondary feature or function), a plurality of inner planets 42a, 42b forming a set of inner planets that engage the second sun 38 but do not engage the second ring 40, a plurality of outer planets 44a, 44b forming a set of outer planets each of which engages the second ring 40 and engages one of the inner planets 42a, 42b, and a carrier 46 (also called a second carrier, which is named this since it is a component of the double pinion planetary gearset which is also called the second planetary gearset thus distinguishing it from the simple carrier, and not necessarily because it has any secondary feature or function) of the inner planets 44a, 44b and inner planets 42a, 42b.

[0058] The three horizontal axes of FIG. 5 A represent respectively, from the bottom to the top, the simple ring 30 rotation speed ratio of the simple planetary gearset 26 of FIG. 5B, the simple carrier 34 rotation speed ratio of the simple planetary gearset 26 of FIG. 5B, and the simple sun 28 rotation speed ratio of the simple planetary gearset 26 of FIG. 5B. The simple sun 28 rotation speed ratio which is also the CVT output shaft 16 speed ratio is shown in different methods of operation. In reverse mode the reverse clutch 48 is engaged which grounds the simple carrier 34. Thus the simple sun 28 ratio (thus CVT ratio) is a negative multiple of the simple planetary Ring/Sun ratio which also reflects the output ring 6 speed ratio of the variator 2. As we see the in reverse mode the simple carrier 34 speed ratio is zero (due to grounding) and the output (simple sun 28) is shown as a negative multiple of the variator low speed ratio (simple ring 30). In direct mode or underdrive mode the direct clutch 50 is engaged, which links the simple carrier 34 with the simple sun 28. Thus the simple carrier 34 and simple sun 28 will rotate at the same speed ratio as the simple ring 30 which is the output of the variator 2. Thus, in direct mode the output shaft 16 speed ratio (CVT OUT) is the same as the variator 2 speed ratio. At maximum speed ratio of the variator 2 (2.0) the simple sun 28 and simple carrier 34 and simple ring 30 are all rotating at a speed ratio of 2 which is the same speed ratio as the carrier 46. The double pinion planetary gearset 36 is connected to the simple planetary gearset 26 via a connection between the second planetary carrier 46 (also called the second carrier) and the simple carrier 34. The second sun 38 is grounded and the second ring 40 is optionally connected to the input shaft 14 via the overdrive clutch 52. The second sun 38, second planets, and second ring 40 gear ratios of the double pinion planetary set 36 are chosen such that, second ring 40 is spinning at the same speed as the input shaft 14when the variator 2 is at maximum speed ratio a synchronous shift to overdrive mode can be made by engaging the overdrive clutch 52 and disengaging the direct mode clutch 50. In overdrive mode the simple carrier 34 is held at a speed ratio of 2.0 by the power connection through the second ring 40 and outer second planets 44a, 44b (at least) to the input shaft 14. Consequently as the variator 2 output speed is reduced the speed ratio differential between the simple ring 30 and simple carrier 34 increases and the simple ring 30 (and output shaft 16) speed ratio can be increased beyond the variator maximum speed ratio. Thus the overdrive speed mode CVT OUT (output shaft 16) speed ratio increases beyond 2.0 as the variator 2 (input/output ring) speed ratio decreases within its operational range.

[0059] In FIG. 5B, the Dual Mode Synchronous Shift CVT uses a 2: 1 OD ("OD" stands for overdrive) shown in the Dual Mode CVT 8.0 OAR version transmission of FIG. 5 A and 5B ("OAR" stands for overall ratio). The double pinion planetary gearset 36 having a second sun 38 and a plurality of pairs of planets respectively comprising inner planets 42a, 42b, and outer planets 44a, 44b, connected by a common second planet carrier 46 and a second ring 40 is shown in FIG. 5B, wherein the second ring 40 is coupled to the simple ring 30 of the simple planetary gearset 26 having a simple sun 28, planet gears 32a, 32b with a simple planet carrier 34, and simple ring 30. The variator 2 is shown with its input ring 4 connected to the input shaft 14 of the CVT transmission and with its output ring 6 connected to the simple ring 30. The simple carrier 34 is selectively coupled to the simple sun 28 by the direct clutch 50 and may also be selectively grounded by the reverse clutch 48. The second carrier 46 and simple carrier 34 are connected, and the second ring 40 is selectively coupled to the input shaft 14 via the overdrive clutch 52. The second sun 38 is grounded. In reverse mode the reverse clutch 48 is engaged which grounds the simple carrier 34. Power flows through the variator 2 to the simple ring 30 and then the simple sun 28 to the output shaft 16. The simple sun 28 spins at a constant speed ratio factor of the simple ring 30 since the simple carrier 34 is grounded. The drawing depicts by example a R/S ratio of 1.5 so the simple sun 28 will spin at a -S/R ratio of the simple ring 30 or -0.75 of the simple ring 30. In direct drive mode the simple carrier 34 is connected to the simple sun 28 via the direct drive clutch 50, all power flows from the input shaft 14 through the variator 2 and to the simple ring 30. Since the simple carrier 34 is connected to the simple sun 28 via the direct drive clutch 50, the simple sun 28 and simple carrier 34 have the same speed as the simple ring 30 and the transmission output shaft 16 speed ratio is the same as the variator 2 speed ratio. At maximum variator speed ratio a synchronous shift to overdrive mode is made by engaging the overdrive clutch 52 and then disengaging the direct drive clutch 50. A synchronous shift is possible because the second sun 38, planets, and second ring 40 gear ratios of the double pinion planetary set 36 are chosen such that the second ring 40 has a matching speed with the input shaft 14 when the variator 2 output is at maximal speed ratio in direct drive mode.

[0060] In overdrive mode, input shaft 14 power is split; a portion flows through the variator 2 to the simple ring 30 and then the simple sun 28, while a portion of power flows through the second ring 40 to the second sun 38 and simple sun 28 and then to the output shaft 16. This particular arrangement is regenerative in that the power flowing through the mechanical path is greater than unity, but the power flowing through the variator is negative and less than unity. The output shaft 16 speed at the simple sun 28 becomes a function of how this power is split. The second ring 40 and second carrier 46 speed is now fixed to the input shaft 14. In Fig. 5A this is shown where the carrier speed ratio is fixed at 2.0 in overdrive mode. The variator output speed ratio is lowered from its maximum to slow simple ring 30 speed ratio. As this is done more the speed ratio differential between the second carrier 46 and second ring 40 gets larger causing the simple sun 28 to spin faster. This also causes less power to flow through the variator 2. This arrangement allows the overdrive mode to achieve higher speed ratios than the variator is capable of alone and increases efficiency at high speeds. As shown in FIG 5B, the gear ratio (R/S) of the simple planetary gearset 26 of simple ring to simple sun is 1.5. Also as shown in FIG 5B, the gear ratio (R/S) of the double pinion planetary gearset 36 of second ring to second sun is 2.0.

[0061] Table 2 below shows the clutch engagement scenarios of the embodiment transmission of FIG. 4B which result in the various modes of operation, i.e. direct drive mode (low mode), reverse mode, and overdrive mode (OD). Table 2.

Example 3 Under-Driven Dual Mode CVT 8.5 OAR

[0062] Provided herein are embodiments of variable transmission configurations that include a variator 2 (alternatively called a CVP herein, such as a tilting-ball type variator 2), a simple planetary gearset 26, a double pinion planetary gearset 36, a reverse clutch 48, a direct mode clutch 50, and an overdrive clutch 52. The embodiments depicted, and obvious variants to one of skill in the art upon reviewing the disclosure herein, provide a dual mode of operation (i.e. a low mode or direct drive mode which in this example is an underdrive mode), and a high mode of operation (i.e. overdrive), at least, as well as a reverse mode. In each embodiment, selective engagement of the reverse drive clutch and/or the direct mode clutch act as starting clutches for the transmission. This embodiment variable transmission is referred to herein as an Under- Driven Dual Mode CVT having a 8.5 OAR ("OAR" stands for overall ratio).

[0063] The simple planetary gearset 26 of FIG. 6B comprises a sun 28 (also called a simple sun, which is named this since it is a component of the simple planetary gearset thus distinguishing it from the second sun, and not necessarily because it has any simple feature or function), a ring 30 (also called a simple ring, which is named this since it is a component of the simple planetary gearset thus distinguishing it from the second ring, and not necessarily because it has any simple feature or function), a plurality of planets 32a, 32b (also called simple planets, which are named this since they are components of the simple planetary gearset thus distinguishing them from the inner and outer planets, and not necessarily because they have any simple feature or function) forming a set of planets, and a carrier 34 (also called a simple carrier, which is named this since it is a component of the simple planetary gearset thus distinguishing it from the second carrier, and not necessarily because it has any simple feature or function). The double pinion planetary gearset 36 of FIG. 6B comprises a sun 38 (also called a second sun, which is named this since it is a component of the double pinion planetary gearset which is also called the second planetary gearset thus distinguishing it from the simple sun, and not necessarily because it has any secondary feature or function), a ring 40 (also called a second ring, which is named this since it is a component of the double pinion planetary gearset which is also called the second planetary gearset thus distinguishing it from the simple ring, and not necessarily because it has any secondary feature or function), a plurality of inner planets 42a, 42b forming a set of inner planets that engage the second sun 38 but do not engage the second ring 40, a plurality of outer planets 44a, 44b forming a set of outer planets each of which engages the second ring 40 and engages one of the inner planets 42a, 42b, and a carrier 46 (also called a second carrier, which is named this since it is a component of the double pinion planetary gearset which is also called the second planetary gearset thus distinguishing it from the simple carrier, and not necessarily because it has any secondary feature or function) of the inner planets 44a, 44b and inner planets 42a, 42b.

[0064] The four horizontal axes of FIG. 6A represent respectively, from the bottom to the top, the double pinion sun 38 rotation speed ratio of FIG. 6B, the rotation speed ratio of the simple ring 30 of the simple planetary gearset 26 of FIG. 6B and of the second ring 40 of the double pinion planetary gearset 36 of FIG. 6B, the rotation speed ratio of both the simple carrier 34 of the simple planetary gearset 26 of FIG. 6B and the second carrier 46 of the double pinion planetary gearset 36 of FIG. 6B, and the simple sun 28 rotation speed ratio of the simple planetary gearset 26 of FIG. 6B. Fig. 6A shows the speed ratios of the various part of the CVT transmission in different drive modes. The second sun 38 speed ratio is the variator output (output ring 6), shown here as varying from speed ratios 0.5 to 2.0 of the input shaft 14 speed. The second planetary carrier is grounded so the second ring 40 speed and the simple ring 30 (SR) speed (shown as Ring-Ring in Fig. 6A), vary as a function of the second sun 38 and the gear ratio of the double pinion planetary gearset 36 CR/CS, here shown as R/S= 2.0. Since second ring/second sun is 2.0 the double pinion planetary gearset 36 essentially underdrives the variator 2. The ring-ring speed will be second sun/second ring times the variator output. In this case Ring-Ring speed ratio is shown as varying from .25-1.0 corresponding to ½ times the variator output (output ring 6). In direct drive mode and reverse mode all the power flows from the input shaft 14 through the variator 2 and double pinion planetary gearset 36. In reverse mode the reverse clutch 48 grounds the simple carrier 34 so the CVT output speed (shown as CVT OUT in FIG. 6A, corresponding to the output shaft 16 speed) at the simple sun 28 is a function of the simple ring 30 speed and the simple planetary gear ratio. In this example the simple planetary gear ratio is depicted as R/S = 1.5. Since simple ring/simple sun = 1.5 the reverse speed ratios of the output, i.e. the simple sun 28 in this embodiment, can vary as -1.5 times the under driven variator 2 speed ratio range which drives the second ring 40 and simple ring 30. Here a single reverse speed is depicted at -0.375 which corresponds to the variator speed output (output ring 6 speed) of 0.5 and the underdriven variator output of 0.25 at the second ring 40. [0065] In direct mode the simple planets 32a, 32b and simple sun 28 are coupled by the direct drive clutch 50, thus they must rotate together and rotate in unison with the simple ring 30. As a result the direct drive mode output speeds match the underdriven variator output. The gear ratios of the planets, carrier 34, simple sun 28 and simple ring 30 of the simple planetary gearset 26 are chosen such that at the maximum variator output speed ratio the simple carrier 34 speed matches the input shaft 14 speed and a synchronous shift to overdrive mode is made by engaging the overdrive clutch 52 and then disengaging the direct drive clutch 50. The shift is synchronous in that all rotating components involved coupling and decoupling are rotating at the same speed. In overdrive mode power flows through the variator 2, as in the direct drive mode, however some of the input shaft 14 power now directly flows to the simple carrier 34. The transmission output speed at simple sun 28 now varies as a function of the simple ring 30 and the simple carrier 34 speed. In this example the simple carrier 34 speed ratio is held constant at 1.0 as it is directly coupled to the input shaft 14. Output speed ratio at simple sun 28 can by increased beyond 2.0 by lowering the variator output speed ratio and in turn the underdriven variator output speed which drives the second ring 40 via the double pinion planetary gearset 36. Increasing the difference in speed ratio between the second ring 40 and the second sun 38 by lowering the variator output increases the simple sun 28 output speed ratio allowing higher overdrive speeds. This causes less power to flow through the variator 2.

[0066] In FIG. 6B, Under-driven Dual Mode CVT, shows a reconfiguration of the Dual Mode Synchronous Shift CVT that uses a direct mechanical path rather than the 2: 1 UD ("UD" stands for underdrive) shown in the Dual Mode CVT 8.0 OAR version transmission of FIG. 6 A and 6B ("OAR" stands for overall ratio). This arrangement uses the exact same content as the arrangements of FIG. 4B and 5B, including the same Ring/Sun ratios for the two planetary gearsets, and simply changes the connections. In this embodiment power flows from the input shaft 14 to the variator input ring 4 and selectively to the simple carrier 34 via the overdrive clutch 52. In direct drive or reverse mode all the power flows from the input shaft 14 through the variator 2. The variator output is connected to the second sun 38. Here the second carrier 46 is grounded which effectively allows the double pinion planetary gearset 36 to underdrive the variator 2. In this example, the speed ratio of the variator output is effectively halved by the double pinion planetary gearset 36 because second ring 40 to second sun 38 gear ratio of the double pinion planetary gearset 36 is 2.0. Simply put the output of the double pinion planetary gearset 36 at second ring 40 is simply an underdriven variator output. Thus underdriven variator output drives the simple ring 30 via the connection between the second ring 40 and the simple ring 30. In direct mode the direct clutch 50 engages the simple carrier 34 to the simple sun 28; consequently simple ring 30, simple carrier 34, and simple sun 28 rotate with matching speed ratio. In direct mode the CVT output speed ratio, at the simple sun 28 is equivalent to the underdriven variator output speed ratio. In reverse mode the simple carrier 34 is grounded so power flows from the simple ring 30 and second ring 40 (equivalent to the power output of the underdriven variator 2) to the simple sun 28 through simple planetary gearset 26. Thus the reverse mode output is a multiple of the underdriven variator output, that multiple being the negative ring to sun ratio (R/S) of the simple planetary gearset 26. In overdrive mode the power flows through from the input shaft 14 to the variator 2 as before but some of the input power is directed to the simple carrier 34 via the overdrive clutch 52. In overdrive the transmission output is a function of the simple carrier 34 and the simple ring 30, with the simple ring 30 being driven by the underdriven variator output (at the second ring) as before. Reducing the variator speed ratio output will in turn reduce the simple ring 30 speed and increase the speed differential between the simple ring 30 and the simple carrier 34. The increase in the speed differential allows the simple sun 28 speed and transmission output speed to rise.

[0067] Table 3 below shows the clutch engagement scenarios of the embodiment transmission of FIG. 6B which result in the various modes of operation, i.e. direct drive mode (low mode), reverse mode, and overdrive mode (OD).

Table 3.

[0068] FIG. 6C shows a plot of transmission efficiency (Y-axis) vs. transmission speed ratio (X- axis), wherein the speed ratio is the inverse of torque ratio of Underdriven Dual Mode CVT 8.5 OAR of FIG. 6 A and 6B. The curve on the left between 0 and 1 on the X-axis is the

transmission efficiency vs. transmission speed ratio when the Underdriven Dual Mode CVT 8.5 OAR is in the direct mode. The curve on the right between 1 and 2.125 on the X-axis is the transmission efficiency vs. transmission speed ratio when the Underdriven Dual Mode CVT 8.5 OAR is in over-drive mode. As the speed ratio varies in the direct mode, efficiency changes due to changing losses in the ball variator. After switching to overdrive mode the speed output of the CVT is increased by lowering the ball variator speed ratio and less power is directed through the ball variator and overall efficiency increases. This graph shows the benefit of the CVT with the overdrive arranged in this configuration as higher efficiencies are attained at higher speed ratios.

[0069] The similarities of the Under-driven Dual Mode CVT of FIGs. 6B relative to the Dual Mode CVT 8.0 OAR are: both have a direct mode in the low range and a power regenerative mode (mechanical path power greater than unity and variator path power negative but absolute value less than unity) in the high mode; both provide the same overall ratio (max speed ratio divided by min speed ratio); both locate the clutches for each function in the same location; both allow the choice of using a torque converter or using two of the clutches as starting clutches ("Direct" clutch for forward and "Rev" clutch for reverse); total vehicle efficiency (crank to axle) is the same in the low direct mode; and the high mode has different losses on the variator, mechanical, and transmission output paths.

[0070] The benefits of the Under-driven Dual Mode CVT over the 8.0 OAR Dual Mode CVT are that there is elimination of the ground connection under the variator balls which allows a single thrust bearing to react the clamp load of the variator rings. That is, the carrier (not called out in Fig. 6B) of the balls is grounded. The carrier is the ground element for the variator (one ring 4 is the variator input, the other ring 6 is the output, and the ball carrier takes the torque reaction to ground). The first two example embodiments described herein in Example 1 and FIGs. 4A, 4B and Example 2 and FIGs. 5A, 5B require the ground connection for the double pinion gearset to be transferred from the grounded carrier, under the variator rings, and ultimately connected to the double pinion gearset. This ground connection forces a second thrust bearing between the input and output rings 4, 6 of the variator 2 to press the input ring 4 and output ring 6 into the balls 8a, 8b. In contrast, in the example embodiment described herein in Example 3 and FIGs. 6A, 6B, and 6C connects the double pinion carrier 46 to ground external from the variator 2. This allows a single thrust bearing to hold the input ring 4 and output ring 6 to the variator balls 8a, 8b. Not only is this cheaper (one bearing vs. two), but the single bearing does not have any relative speed at the 1 : 1 speed ratio while the dual bearing design does have a relative speed to ground in both bearings at 1 : 1. This will result in lower losses for the embodiments of Example 3 and FIGs. 6A, 6B, and 6C.

[0071] Further, the speed ratio range has been shifted lower by a factor of two (i.e. the original CVT speed ratio range of 0.5 UD to 4.25 OD has now been reduced to 0.25 UD to 2.125 OD in the embodiments of Example 3 and FIGs. 6A, 6B, and 6C). The range of the embodiments of Example 3 and FIGs. 6A, 6B, and 6C, thus, is very close to the speed ratios used by the current 6, 7, and 8 speed automatic transmissions in current production vehicles which will allow the use of the production hypoid rear axle ratio. This provides the function of an add-on speed reducer without the additional expense of such a separate device.

[0072] The embodiments disclosed herein may be used by Other CVT manufactures that use a co-axial variator and intend to execute a synchronous mode shift could be interested in this powerflow.

[0073] Although specific embodiments are disclosed herein, alternative embodiments are contemplated herein which alter the embodiments described and shown herein by various ways known to one of skill in the art upon reading the disclosure herein, or in ways that would be obvious to one of skill in the art upon reading the disclosure herein. These alternatives would achieve similar results despite changes to the specific embodiments shown and described herein without departing from the inventions described. For non-limiting example, an extra gearset may be added, such as either a dedicated reverse gearset or a gearset that provides the variator underdrive ratio to allow the transmission to function in the IVT mode (the transmission would now be a triple mode CVT and could either function as an IVT or simply use the reverse range of the IVT with a conventional starting device).

[0074] While the figures and description herein are directed to ball-type variators (CVTs), alternate embodiments are contemplated another version of a variator (CVT), such as a

Variable-diameter pulley (VDP) or Reeves drive, a toroidal or roller-based CVT (Extroid CVT), a Magnetic CVT or mCVT, Ratcheting CVT, Hydrostatic CVTs, Naudic Incremental CVT (iCVT), Cone CVTs, Radial roller CVT, Planetary CVT, or any other version CVT.

[0075] While preferred embodiments of the present invention 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 invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.