PLANETARY TRANSMISSION

CROSS-REFERENCES TO RELATED APPLICATIONS

[0001] The present application claims the benefit of U.S. Provisional Patent Application No. 61/819,414, filed May 3, 2013 which application is incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] A vehicle having a driveline including a continuously variable transmission allows an operator of the vehicle or a control system of the vehicle to vary a drive ratio in a stepless manner, permitting a power source of the vehicle to operate at its most efficient rotational speed.

Continuously variable transmissions known in the art tend to have limited ratio ranges and are typically limited to transmitting smaller amounts of power.

SUMMARY OF THE INVENTION

[0003] Provided herein is a variable transmission comprising a stationary housing, an input shaft, an output shaft, a compound planetary gearset (gearset #1) having first, second, third, and fourth rotating elements; a second planetary gearset (gearset #2) having first, second, and third rotating elements; a variator assembly having first and second rotating elements; and four selectable torque transmitting devices; wherein the input shaft is fixedly connected with the first element of the variator assembly; the second rotating element of the variator assembly is fixedly connected with the first rotating element of the compound planetary gearset; the output shaft is fixedly connected with the third rotating element of the compound planetary gearset; a first clutch causes the fourth rotating element of the compound planetary gearset to stop rotating, establishing a first forward variable range of overall transmission speed ratios; a second clutch connects the input shaft to the second rotating element of the compound planetary gearset to establish a second forward variable range of overall transmission speed ratios; a third clutch establishes a fixed ratio between the input shaft speed and the speed of the fourth rotating element of the compound planetary gearset, establishing a third forward variable range of overall transmission speed ratios; a fourth clutch connects the second rotating element of the compound planetary gearset to ground, establishing a reverse variable range of overall

transmission speed ratios; and the variator establishes a controlled, variable ratio between the speeds of its first and second rotating elements, thereby adjusting the overall transmission speed ratio within any of said variable ranges. Provided herein is a variable transmission wherein the third rotating element of the second planetary gearset is fixedly connected to ground, the first clutch connects the fourth rotating element of the compound planetary gearset to ground, the third clutch connects the input shaft to the second rotating element of the second planetary gearset, and the fourth rotating element of the compound gearset is fixedly connected with the first rotating element of the second planetary gearset. In another embodiment, the third rotating element of the second planetary gearset is fixedly connected to ground, the first clutch connects any two of the second planetary gearset' s three rotating elements, causing all of them to rotate at a common (zero) speed; the third clutch connects the input shaft to the second rotating element of the second planetary gearset, and the fourth rotating element of the compound planetary gearset is fixedly connected with the first rotating element of the second planetary gearset. In still another embodiment, the input shaft is fixedly connected with the second rotating element of the second planetary gearset, the first clutch connects the fourth rotating element of the compound planetary gearset to ground, the third clutch connects the third rotating element of the second planetary gearset to ground and the fourth rotating element of the compound gearset is fixedly connected with the first rotating element of the second planetary gearset. In a further embodiment, the input shaft is fixedly connected with the second rotating element of the second planetary gearset, the input shaft is fixedly connected with the second rotating element of the second planetary gearset, the input shaft is fixedly connected with the second rotating element of the second planetary gearset, the third rotating element of the second planetary gearset is fixedly connected to ground, the first clutch connects the fourth rotating element of the compound planetary gearset to ground, and the third clutch connects the fourth rotating element of the compound planetary gearset to the first rotating element of the second planetary gearset.

Provided herein is a variable transmission having a compound planetary gearset comprising a ring gear, a carrier assembly rotatably supporting an outer set of long pinions in mesh with said ring gear and an inner set of short pinions in mesh with said outer long pinions, a first sun gear meshing with said long outer pinions, and a second sun gear meshing with said short inner pinions; and wherein the first rotating element of the compound planetary gearset is the first sun gear; the second rotating element of the compound planetary gearset is said carrier assembly; the third rotating element of the compound planetary gearset is said ring gear; and the fourth rotating element of the compound planetary gearset is said second sun gear. Further, the second planetary gearset is a simple planetary gearset comprising a second ring gear, a second carrier assembly rotatably supporting a third set of pinions in mesh with said second ring gear, and a third sun gear in mesh with said third pinions, and wherein the first rotating element of the second planetary gearset is said second ring gear, the second rotating element of the second planetary gearset is said second carrier assembly, the third rotating element of the second planetary gearset is said third sun gear. Provided herein is a ball-type variator comprising a carrier assembly rotatably supporting a set of pivoting axles rotatably disposed about the transmission axis, said axles each further rotatably supporting a ball; and first and second ring assemblies, each comprising a ball contact area in continuous contact with all of said balls, and wherein the first rotating element of the variator is said first ring assembly; the second rotating element of the variator is said second ring assembly; and the carrier assembly moves in controlled fashion through a small range of angles with respect to the variator housing in order to cause the pivoting axles to change orientation, thus changing the speed ratio between said first and second ring assemblies. Provided herein is a transmission wherein as the variator speed ratio between the first and second assembly rings increases, the overall transmission speed ratio within said first forward range increases; the overall transmission speed ratio within said second forward range decreases; the overall transmission speed ratio within said third forward range increases; the overall transmission speed ratio within said reverse range becomes more negative. Provided herein is a transmission wherein at a variator speed ratio which is near the lower end of the variator speed ratio range but still within said range, the overall transmission speed ratios in said second and third forward ranges are the same; said third clutch can be synchronously engaged while in said second forward range; said second clutch can be synchronously engaged while in said third forward range; and an additional, fixed-ratio transmission operating mode, which transmits no power through the variator, is established by simultaneous engagement of said second and third clutches. In addition, said second and/or third clutches are dog-style clutches. Provided herein is a variable transmission comprising an input member, an output member, two planetary gearsets that are connected to form a compound planetary gearset assembly, (alternatively called herein gearset #1), and also referred to as a Ravigneaux planetary gearset, a third planetary gearset, (alternatively called herein gearset #2), a plurality of torque transmitting devices that include a plurality of clutches, and a variator comprising a plurality of tilting variators balls disposed between a first drive ring (or a first ring assembly) and a second drive ring (or a second ring assembly). The compound planetary gearset assembly has a single, common carrier having two radii for rotatably supporting a first (inner) plurality of pinion gears (planets) and a second (outer) plurality of pinion gears (planets), two sun gears, one large and one small, and a common ring gear. The two sets of planet gears rotate independently of the carrier, but corotate in a fixed gear ratio with respect to each other. The inner planets couple to the small sun gear and corotate at a fixed ratio, whereas the outer planets couple to the large sun and also corotate at a fixed ratio. The ring gear also couples to the outer planets and corotates at a fixed ratio. The third planetary gearset, (alternatively gearset #2) comprises a sun gear, a carrier supporting a plurality of pinion gears (planets) coupled to the third sun gear, and a ring gear coupled to the planets, wherein the gearset #2 corotates at a fixed ratio. This transmission configuration can produce three forward modes with decreasing power through the variator in each successive mode leading to higher efficiency at fuel efficient relevant speeds. Thus, provided herein is a continuously variable transmission comprising: an input shaft; an output shaft; and a first ring assembly rotatably disposed in a housing drivingly engaged with the input shaft, the first ring assembly comprising a first variator ball engagement surface that is in driving engagement with a plurality of variator balls. The variable planetary transmission further comprises a grounded variator carrier assembly comprising an annular arrangement of the plurality of tiltable variator balls each having a ball axle shaft. The variable transmission further comprises a second ring assembly rotatably disposed in the housing comprising a second variator ball engagement surface that is in driving engagement with each of the variator balls. In this embodiment of the present invention, the output of the variator is drivingly engaged to the large sun gear in the compound planetary gearset assembly (alternatively gearset #1). As the first clutch is engaged, the second sun gear of the compound planetary gearset assembly is grounded. This causes the compound planetary gearset to establish an underdrive ratio between the variator output and the transmission output. In another embodiment of the present invention, a second clutch is engaged in a synchronous fashion. As the variator speed ratio approaches 1.8, the second forward mode can be synchronously engaged as the slip across the second clutch approaches zero, wherein the second clutch can be fully engaged with no change in speeds of any transmission components. Still further in this embodiment of the present invention, a third clutch may be engaged in a synchronous fashion. When the first clutch is released, the variator ratio can be controlled back down toward 0.5 as the vehicle continues to accelerate. As the speed of the variator approaches the end of the speed ratio range, the third forward mode can be synchronously engaged as the slip across the third clutch drops to zero, and the new ratio can be engaged in synchronous fashion while releasing the second clutch. In still another embodiment of the present invention, a reverse braking clutch is engaged to ground the carrier of the compound planetary gearset assembly, thus reversing the output from the large sun to the carrier ring, and providing a reverse mode to the output shaft. In yet another embodiment of the present invention, a neutral mode can be attained by releasing all torque transmitting clutches.

INCORPORATION BY REFERENCE

[0004] 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

[0005] 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:

[0006] Figure 1 is a lever diagram illustration of the continuously variable transmission which provides the speed ratio ranges illustrated in Figure 3;

[0007] Figure 2 is a stick diagram illustration of one embodiment of the inventive transmission, as shown in Figure 1 ;

[0008] Figure 3 is a graph of a speed diagram illustrating the speed ratio ranges of the inventive transmission and mapping the continuously variable planetary ratio range of each mode.;

[0009] Figure 4 is a cutaway view of a currently known and used continuously variable transmission (CVT); and

[0010] Figure 5 is a magnified cutaway view of a ball and ring of the CVT of Figure 4.

DETAILED DESCRIPTION OF THE INVENTION

[0011] Provided herein is a variable transmission comprising an input member, an output member, two planetary gearsets that are connected to form a compound planetary gearset assembly, (alternatively called herein gearset #1), and also referred to as a Ravigneaux planetary gearset, a third planetary gearset, (alternatively called herein gearset #2), a plurality of torque transmitting devices that include a plurality of clutches and a variator or Constant Variable Planetary, also known as a CVP, comprising a plurality of tilting variators balls disposed between a first drive ring (or a first ring assembly) and a second drive ring (or a second ring assembly). The compound planetary gearset assembly has a single, common carrier having two radii for rotatably supporting a first (inner) plurality of pinion gears (planets) and a second (outer) plurality of pinion gears (planets), two sun gears, one large and one small, and a common ring gear. The two sets of planet gears rotate independently of the carrier, but corotate in a fixed gear ratio with respect to each other. The inner planets couple to the small sun gear of the compound planetary gearset and corotate at a fixed ratio, whereas the outer planets couple to the large sun of the compound planetary gearset and also corotate at a fixed ratio. The ring gear also couples to the outer planets of the compound planetary gearset and corotates at a fixed ratio. The third planetary gearset, or gearset #2, comprises a sun gear, a carrier supporting a plurality of pinion gears (planets) coupled to the third sun gear, and a ring gear coupled to the planets, wherein the gearset #2 also corotates at a fixed ratio. This transmission configuration can produce three forward modes with decreasing power through the variator in each successive mode leading to higher efficiency at fuel efficient relevant speeds. The ratio range resulting from the configurations described herein, or obvious to one of skill in the art having read such disclosure, will be wider than the variator range and sufficient for a vehicle. Additional variable transmission details are described in U.S. Application No. 13/743,951 filed Jan 17, 2013, and/or PCT/US2013/026037 filed Feb. 14, 2013, incorporated herein by reference in their entirety.

[0012] The variable transmission that employs a ball type Continuously Variable Transmission (CVT, which is also known as CVP for constant variable planetary, herein) may replace a conventional transmission in a vehicle, such as a rear wheel drive automobile. The transmissions disclosed herein may be used in any vehicle type that needs or uses a transmission.

[0013] Basic concepts of a ball type Continuously Variable Transmissions are described in US20040616399 and AU2011224083A1, incorporated herein by reference in their

entirety. Such a CVT, adapted herein as described throughout this specification, comprises a number of balls 997, depending on the application, two discs with a conical surface contact with the balls, as input 995 and output 996, and an idler 999 as shown on FIG. 4. The balls are mounted on axes 998, themselves held in a cage or carrier allowing changing the ratio by tilting the balls' axes. Other types of ball CVTs also exist, like the one produced by Milner, but are slightly different.

[0014] The working principle of such a CVP of FIG. 4 is shown on FIG. 5. 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 can be changed between input and output. When the axis 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 balls' axes are tilted at the same time with a mechanism included in the cage.

[0015] Thus, provided herein is a continuously variable transmission comprising: an input shaft; an output shaft; and a first ring assembly rotatably disposed in a housing drivingly engaged with the input shaft and the first ring assembly comprising a first variator ball engagement surface that is in driving engagement with a plurality of variator balls. The variable transmission, in certain embodiments, further comprises a grounded variator carrier assembly, a plurality of planet gears rotatably disposed in the variator carrier assembly, and a ring gear, the variator carrier assembly comprising an annular arrangement of the plurality of tiltable variator balls each having a ball axle shaft. The variable transmission, in certain embodiments, further comprises a second ring assembly rotatably disposed in the housing comprising a second variator ball engagement surface that is in driving engagement with each of the variator balls. The variable transmission further comprises a Ravigneaux gearset assembly comprised of two planetary gearsets that are coupled into a compound planetary gearset assembly (gearset #1), a third planetary gearset (gearset #2), and a plurality of torque transmitting devices that include several clutches and braking clutches. The variable transmission, in this embodiment, has a compound planetary gearset assembly with a single, common carrier having two radii for rotatably supporting a first (inner) plurality of pinion gears (planets) and a second (outer) plurality of pinion gears (planets), two sun gears, one large and one small, and a common ring gear; all of which in proper combination, independently corotate at a fixed ratio. The variable transmission, in certain embodiments, can be engaged in various forward modes or a reverse mode, through selective synchronous engagement or release of said clutches and braking clutches.

[0016] Referring now to FIG. 1, an embodiment of a 4-mode rear wheel drive continuously variable planetary transmission 10 is illustrated in a lever diagram format, wherein a four node lever is connected to a three node lever. A lever diagram is a schematic representation of the components of a mechanical device such as an automatic transmission. Each individual lever represents a planetary gearset wherein the three basic mechanical components of the planetary gear are each represented by a node. Therefore, a single lever contains three nodes: one for the sun gear, one for the planet gear carrier, and one for the ring gear. In some cases, two levers may be combined into a single lever having more than three nodes (typically four nodes). For example, if two nodes on two different levers are interconnected through a fixed connection they may be represented as a single node on a single lever. The relative length between the nodes of each lever can be used to represent the ring-to-sun ratio of each respective gearset. These lever ratios, in turn, are used to vary the gear ratios of the transmission in order to achieve an appropriate ratio and ratio progression. Mechanical couplings or interconnections between the nodes of the various planetary gearsets are illustrated by solid lines and torque transmitting devices such as clutches and brakes are presented as interleaved fingers. Further explanation of the format, purpose and use of lever diagrams can be found in SAE Paper 810102, "The Lever Analogy: A New Tool in Transmission Analysis" by Benford and Leising which is hereby fully incorporated by reference.

[0017] The transmission 10 includes an input shaft 12, a CVP or variator 5, a first planetary gearset 25, and a second planetary gearset 27, coupled together into a compound planetary gearset assembly, (gearset #1) 20, a third planetary gearset (gearset #2) 30, and an output shaft 51. In the lever diagram of FIG. 1, the levers for the first planetary gearset and the second planetary gearset have been interconnected into a single four node lever 20 (compound planetary gearset assembly, or gearset #1) having: a first node 21 (sun gear 1), a second node 22, (planet carrier 1-2), a third node 24 (ring gear 1-2), and a fourth node 23 (sun gear 2). Thus the planetary gear carrier 22, is the common planetary carrier for the first planetary gearset and the second planetary gearset, and the ring gear 24 is the output for both gearset one and gearset two and is driven by the planet gears of gearset one. The three node lever of the third planetary gearset (gearset #2) 30 is then coupleable to the four node lever of the compound planetary gearset assembly (gearset #1) at the fourth node of the four node assembly, 23, (sun gear 2) and first node of the three node assembly, 33, (ring gear 3) respectively. In the first forward mode, the input shaft 12 is directly coupled to the variator 5, driving the load through the variator balls in the variator assembly, which in turn, couples to the first sun gear 21 of the compound planet gearset assembly (gearset #1) 20, (the first node of the four node lever), the first clutch has been engaged to ground the second sun gear 23. In turn, the first sun gear 21 directly engages the planet gears of gearset one and the compound planetary gear assembly carrier 22, at the second node, which in turn engages the common output ring gear 24, engaging the output shaft 51 at the third node of the four node lever.

[0018] As the first clutch is disengaged, a second clutch 42 synchronously selectively connects the input shaft 12 to the common planetary gear carrier at node 22 of the compound planetary gearset assembly (gearset #1) with the output ring gear at node 24, which engages the output shaft 51 at the third node of the four node lever to engage the second forward mode.

[0019] A third clutch 43 selectively connects the input shaft 12 to the second planetary gear carrier 32 of the third planetary gearset (gearset #2) 30, (depicted by the three node lever), as the second clutch synchronously disengages, wherein, with the sun gear 31 grounded, drives the ring gear 33 which engages the second planetary sun gear 23 at the forth node of the four node lever, thereby driving the output through the planets of the compound planetary gearset assembly (gearset #1) to the common ring carrier 24, at the third node of the four node lever, providing a third forward mode to the output shaft 51.

[0020] A reverse braking clutch 45 may selectively engage the planetary gear carrier 22 of the compound planetary gear assembly 20 at the second node of the four node lever, thus reversing the output from the first sun gear 21 to the common ring carrier 24, at the third node of the four node lever, and generating a reverse mode to the output shaft 51.

[0021] Finally, when an alternative first clutch 41 A is applied to the third sun 31 of the third planetary gearset (gearset #2) 30, the entire gearset rotates at the same speed. Since the sun gear 31 is permanently grounded, this causes all of planetary gearset 30 to stop rotating. In addition, since the sun gear 23 within the compound planetary gearset assembly (gearset #1) 20 is rigidly connected to the ring gear 33 of the third planetary set (gearset #2) 30, it too will stop rotating. This in turn transfers all power back through the variator 5 and places the transmission in mode one. This is the same effect as the original first clutch; hence, either location works.

[0022] Referring now to FIG. 2, a diagrammatic illustration of an embodiment of a 4-mode rear wheel drive, continuously variable planetary transmission 10 is shown, illustrating what is described by the lever diagram in FIG. 1. This is one of several possible variations.

[0023] As shown, input power can enter the CVP, 5, through the input shaft 12, selectively engaging the a first ring assembly rotatably disposed in a housing, the first ring assembly comprising a first variator ball engagement surface, 6, that is in driving engagement with a plurality of tiltable variator balls 9, each on a ball axis shaft, dispersed within a carrier 7 which is grounded within the housing at 44. The variable transmission further comprises a second ring assembly rotatably disposed in the housing drivingly engaged with the output shaft, the second ring assembly comprising a second variator ball engagement surface, 8, that is in driving engagement with each of the variator balls. The variable transmission has a continuously variable operating mode.

[0024] In a first forward mode embodiment of the present invention, the output power of the variator 5 is at 100% and the speed ratio is at a minimum and is engaged to the sun gear 21 in the compound planetary gearset assembly 20 (gearset #1), as the slip across the first clutch 41 approaches zero and is engaged, grounding the second sun gear 23 of the compound planetary gearset assembly 20, in turn driving the compound assembly planetary carrier 22, thereby engaging the compound assembly ring gear 24, generating a first gear output to the drive shaft 51.

[0025] In a second forward mode embodiment, when in first gear, as the variator 5 speed ratio approaches the maximum end (1.8), the second clutch 42 can be initialized. As the slip across the second clutch 42 approaches zero, it can be synchronously engaged, releasing the first clutch 41, with no change in speeds of any of the transmission components. This engages the compound assembly carrier 22 of the compound planetary gearset 20 (gearset #1), driving the entire gearset ratio through to the common ring gear 24, generating a second gear output to the drive shaft 51.

[0026] In yet a third forward mode embodiment, after the second clutch 42 is engaged, the variator speed ratio can be controlled back down toward the minimum end of the ratio (0.5), as the vehicle continues to accelerate, and the variator power drops. As the variator ratio approaches 0.5, the third clutch 43 can be initialized. As the slip across the third clutch 43 approaches zero, it can be synchronously engaged, releasing the second clutch 42, engaging the second planetary carrier 32 of the third planetary gearset 30 (gearset #2), thus connecting the second ring gear 33, to the second sun gear 23 and allowing both the variator speed ratio and transmission speed ratio to accelerate to the maximum ends of their ranges in third gear.

[0027] In still another embodiment, the reverse braking clutch 45 can be engaged to the planetary gear carrier 22 of the compound planetary gear assembly 20, thus reversing the output to the ring carrier 24, providing a reverse mode to the output shaft 51.

[0028] Referring now to FIG. 3, a speed diagram shows the speed ratio ranges of the

transmission and mapping of the CVP ratio range on to each mode of the transmission. As the diagram illustrates, the shifts between modes are synchronous. Or in other words, e.g., the transmission can be "in" 1 ^st and 2 ^nd mode simultaneously, utilizing no shift energy when the continuously variable planetary (CVP) is at the end of the speed ratio range.

[0029] 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.