Abstract:
Devices and methods are provided herein for the transmission of power in motor vehicles. Power is transmitted in a smoother and more efficient manner by splitting torque into two or more torque paths. A continuously variable transmission is provided with a ball variator assembly having an array of balls, a planetary gearset coupled thereto and an arrangement of rotatable shafts with multiple gears and clutches that extend the ratio range of the variator. In some embodiments, clutches are coupled to the gear sets to enable synchronous shifting of gear modes.

Description:
RELATED APPLICATION 
       [0001]    The present application claims priority to and the benefit from Provisional U.S. Patent Application Ser. No. 62/315,369 filed on Mar. 30, 2016. The content of the above-noted patent application is hereby expressly incorporated by reference into the detailed description of the present application. 
     
    
     BACKGROUND 
       [0002]    A driveline including a continuously variable transmission allows an operator or a control system to vary a drive ratio in a stepless manner, permitting a power source to operate at its most advantageous operating point. 
       SUMMARY 
       [0003]    Provided herein is a continuously variable transmission including a first rotatable shaft operably coupleable to a source of rotational power; a second rotatable shaft aligned coaxial with the first rotatable shaft, the first rotatable shaft and the second rotatable shaft forming a main axis; a variator assembly having a first traction ring assembly and a second traction ring assembly in contact with a plurality of balls, wherein each ball of the plurality of balls has a tillable axis of rotation, the variator assembly is coaxial with the main axis; a first planetary gearset having a first sun gear operably coupled to the second rotatable shaft, a first planet carrier operably coupled to the first rotatable shaft, and a first ring gear coupled to the second traction ring assembly; a first-and-third mode clutch operably coupled to the first ring gear, the first-and-third mode clutch coaxial with the main axis; a countershaft arranged parallel to the main axis; a second planetary gear set coaxial with the countershaft, the second planetary gear set having a second sun gear, a second planet carrier, and a second ring gear; a third planetary gear set coaxial with the countershaft, the third planetary gear set having a third sun gear, a third planet carrier, and a third ring gear; a second-and-fourth mode clutch coaxial with the countershaft, the second-and-fourth mode clutch operably coupled to the second sun gear and the third sun gear; a first synchronizer clutch coaxial with the countershaft, the first synchronizer clutch operably coupled to the second ring gear; and a second synchronizer clutch coaxial with the countershaft, the second synchronizer clutch operably coupled to the third ring gear. 
         [0004]    Provided herein is a method of operating a continuously variable transmission, the method including providing a continuously variable transmission including: a first rotatable shaft operably coupleable to a source of rotational power; a second rotatable shaft aligned coaxial with the first rotatable shaft, the first rotatable shaft and the second rotatable shaft forming a main axis; a variator assembly having a first traction ring assembly and a second traction ring assembly in contact with a plurality of balls, wherein each ball of the plurality of balls has a tillable axis of rotation, the variator assembly is coaxial with the main axis; a first planetary gearset having a first sun gear operably coupled to the second rotatable shaft, a first planet carrier operably coupled to the first rotatable shaft, and a first ring gear coupled to the second traction ring assembly; a first-and-third mode clutch operably coupled to the first ring gear, the first-and-third mode clutch coaxial with the main axis; a countershaft arranged parallel to the main axis; a second planetary gear set coaxial with the countershaft, the second planetary gear set having a second sun gear, a second planet carrier, and a second ring gear; a third planetary gear set coaxial with the countershaft, the third planetary gear set having a third sun gear, a third planet carrier, and a third ring gear; a second-and-fourth mode clutch coaxial with the countershaft, the second-and-fourth mode clutch operably coupled to the second sun gear and the third sun gear; a first synchronizer clutch coaxial with the countershaft, the first synchronizer clutch operably coupled to the second ring gear; and a second synchronizer clutch coaxial with the countershaft, the second synchronizer clutch operably coupled to the third ring gear; engaging the first-and-third mode clutch to operate in a first mode of operation and a third mode of operation; engaging the second-and-fourth mode clutch to operate in a second mode of operation and a fourth mode of operation. 
         [0005]    Provided herein is a vehicle driveline including a power source, a variable transmission of any of described herein drivingly engaged with the power source, and a vehicle output drivingly engaged with the variable transmission. 
         [0006]    Provided herein is a vehicle including the variable transmission of any one of the transmissions described herein. 
         [0007]    Provided herein is a method including providing a variable transmission of any one of the transmissions described herein. 
         [0008]    Provided herein is a method including providing a vehicle driveline of the kind described herein. 
         [0009]    Provided herein is a method including providing a vehicle having any one of the transmission described herein. 
       INCORPORATION BY REFERENCE 
       [0010]    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 
         [0011]    The novel features of the preferred embodiments are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present embodiments will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the preferred embodiments are utilized, and the accompanying drawings of which: 
           [0012]      FIG. 1  is a side sectional view of a ball-type variator. 
           [0013]      FIG. 2  is a plan view of a carrier member that is used in the variator of  FIG. 1 . 
           [0014]      FIG. 3  is an illustrative view of different tilt positions of the ball-type variator of  FIG. 1 . 
           [0015]      FIG. 4  is a schematic diagram of a planetary powersplit continuously variable transmission. 
           [0016]      FIG. 5  is a table depicting operating modes and corresponding clutch engagement for the transmission of  FIG. 4 . 
           [0017]      FIG. 6  is a schematic diagram depicting power flow through a powersplit variator assembly used in the transmission of  FIG. 4 . 
           [0018]      FIG. 7  is another schematic diagram depicting power flow through a powersplit variator assembly used in the transmission of  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0019]    The preferred embodiments will now be described with reference to the accompanying figures, wherein like numerals refer to like elements throughout. The terminology used in the descriptions below is not to be interpreted in any limited or restrictive manner simply because it is used in conjunction with detailed descriptions of certain specific embodiments. Furthermore, the preferred embodiments includes several novel features, no single one of which is solely responsible for its desirable attributes or which is essential to practicing the preferred embodiments described. 
         [0020]    Provided herein are configurations of continuously variable transmissions (CVTs) based on a ball type variators, also known as CVP, for continuously variable planetary. Basic concepts of a ball type Continuously Variable Transmissions are described in U.S. Pat. Nos. 8,469,856 and 8,870,711 incorporated herein by reference in their entirety. Such a CVT, adapted herein as described throughout this specification, includes a number of balls (planets, spheres)  1 , depending on the application, two ring (disc) assemblies with a conical surface in contact with the balls, an input traction ring  2 , an output traction ring  3 , and an idler (sun) assembly  4  as shown on  FIG. 1 . The balls are mounted on tiltable axles  5 , themselves held in a carrier (stator, cage) assembly having a first carrier member  6  operably coupled to a second carrier member  7 . The first carrier member  6  rotates with respect to the second carrier member  7 , and vice versa. In some embodiments, the first carrier member  6  is fixed from rotation while the second carrier member  7  is configured to rotate with respect to the first carrier member, and vice versa. In one embodiment, the first carrier member  6  is provided with a number of radial guide slots  8 . The second carrier member  7  is provided with a number of radially offset guide slots  9 , as illustrated in  FIG. 2 . The radial guide slots  8  and the radially offset guide slots  9  are adapted to guide the tiltable axles  5 . The axles  5  are adjusted to achieve a desired ratio of input speed to output speed during operation of the CVT. In some embodiments, adjustment of the axles  5  involves control of the position of the first and second carrier members to impart a tilting of the axles  5  and thereby adjusts the speed ratio of the variator. Other types of ball CVTs also exist, but are slightly different. 
         [0021]    The working principle of such a CVP of  FIG. 1  is shown on  FIG. 3 . The CVP itself works with a traction fluid. The lubricant between the ball and the conical rings acts as a solid at high pressure, transferring the power from the input ring, through the balls, to the output ring. By tilting the balls&#39; axes, the ratio is changed between input and output. When the axis is horizontal the ratio is one, illustrated in  FIG. 3 , when the axis is tilted the distance between the axis and the contact point change, modifying the overall ratio. All the balls&#39; axes are tilted at the same time with a mechanism included in the carrier and/or idler. Embodiments disclosed here are related to the control of a variator and/or a CVT using generally spherical planets each having a tiltable axis of rotation that are adjusted to achieve a desired ratio of input speed to output speed during operation. In some embodiments, adjustment of said axis of rotation involves angular misalignment of the planet axis in a first plane in order to achieve an angular adjustment of the planet axis in a second plane that is perpendicular to the first plane, thereby adjusting the speed ratio of the variator. The angular misalignment in the first plane is referred to here as “skew”, “skew angle”, and/or “skew condition”. In one embodiment, a control system coordinates the use of a skew angle to generate forces between certain contacting components in the variator that will tilt the planet axis of rotation. The tilting of the planet axis of rotation adjusts the speed ratio of the variator. 
         [0022]    For description purposes, the term “radial” is used here to indicate a direction or position that is perpendicular relative to a longitudinal axis of a transmission or variator. The term “axial” as used here refers to a direction or position along an axis that is parallel to a main or longitudinal axis of a transmission or variator. For clarity and conciseness, at times similar components labeled similarly (for example, bearing  1011 A and bearing  1011 B) will be referred to collectively by a single label (for example, bearing  1011 ). 
         [0023]    As used here, the terms “operationally connected,” “operationally coupled”, “operationally linked”, “operably connected”, “operably coupled”, “operably linked,” “operably coupleable” and like terms, refer to a relationship (mechanical, linkage, coupling, etc.) between elements whereby operation of one element results in a corresponding, following, or simultaneous operation or actuation of a second element. It is noted that in using said terms to describe inventive embodiments, specific structures or mechanisms that link or couple the elements are typically described. However, unless otherwise specifically stated, when one of said terms is used, the term indicates that the actual linkage or coupling take a variety of forms, which in certain instances will be readily apparent to a person of ordinary skill in the relevant technology. 
         [0024]    It should be noted that reference herein to “traction” does not exclude applications where the dominant or exclusive mode of power transfer is through “friction.” Without attempting to establish a categorical difference between traction and friction drives here, generally these are typically understood as different regimes of power transfer. Traction drives usually involve the transfer of power between two elements by shear forces in a thin fluid layer trapped between the elements. The fluids used in these applications usually exhibit traction coefficients greater than conventional mineral oils. The traction coefficient (μ) represents the maximum available traction force which would be available at the interfaces of the contacting components and is the ratio of the maximum available drive torque per contact force. Typically, friction drives generally relate to transferring power between two elements by frictional forces between the elements. For the purposes of this disclosure, it should be understood that the CVTs described here operate in both tractive and frictional applications. For example, in the embodiment where a CVT is used for a bicycle application, the CVT operates at times as a friction drive and at other times as a traction drive, depending on the torque and speed conditions present during operation. 
         [0025]    Referring now to  FIG. 4 , in some embodiments, a continuously variable transmission (CVT)  10  is provided with a first rotatable shaft  11  adapted to receive power from a source of rotational power. In some embodiments, the first rotatable shaft  11  is operably coupled to a torque converter device, or other common coupling. The CVT  10  is provided with a variator (CVP)  12  aligned coaxially with the first rotatable shaft  11 . In some embodiments, the variator  12  is similar to the variator depicted in  FIGS. 1-3 . The variator  12  includes a first traction ring assembly  13  and a second traction ring assembly  14  in contact with a number of balls. In some embodiments, the CVT  10  includes a first planetary gear set  15  aligned coaxially with the first rotatable shaft  11  and the variator  12 . The first planetary gear set  15  includes a first ring gear  16 , a first planet carrier  17 , and a first sun gear  18 . In some embodiments, the first planet carrier  17  is coupled to the first rotatable shaft  11 . In some embodiments, the first planet carrier  17  is operably coupled to a number of planet gears that are optionally configured as stepped gears. The first ring gear  16  is coupled to the second traction ring assembly  14 . In some embodiments, a first-and-third mode clutch  19  is coupled to the ring gear  16 . The sun gear  18  is coupled to a second rotatable shaft  20 . The second rotatable shaft  20  is coaxial with the first rotatable shaft  11  and forms a main axis. In some embodiments, a first gear set  21  is configured to couple the second rotatable shaft  20  to a countershaft  22 . The countershaft  22  is parallel to the main axis. 
         [0026]    Still referring to  FIG. 4 , in some embodiments, the CVT  10  includes a second-and-fourth mode clutch  23  arranged coaxially with the countershaft  22 . The second-and-fourth mode clutch  23  is operably coupled to a second planetary gear set  24  and a third planetary gear set  25 . The second planetary gear set  24  and the third planetary gear set  25  are arranged coaxially with the countershaft  22 . In some embodiments, the second planetary gear set  24  includes a second ring gear  26 , a second planet carrier  27 , and a second sun gear  28 . In some embodiments, the third planetary gear set  25  includes a third ring gear  29 , a third planet carrier  30 , and a third sun gear  31 . The second-and-fourth mode clutch  23  is configured to selectively couple the second sun gear  28  and the third sun gear  31 . In some embodiments, the CVT  10  includes a first synchronizer clutch  32  arranged coaxially on the countershaft  22 . The first synchronizer clutch  32  is operably coupled to the second ring gear  26 . The CVT  10  includes a second synchronizer clutch  33  operably coupled to the third ring gear  29 . In some embodiments, the first synchronizer clutch  32  is configured to selectively engage the second ring gear  26  and the second planet carrier  27 . The second synchronizer clutch  33  is configured to selectively engage the third ring gear  29  to the third planet carrier  30 . 
         [0027]    Typically, synchronizer mechanisms (referred to herein as “synchronizer clutch”) used in power transmissions include a dog clutch integrated with a speed-matching device such as a cone-clutch. During operation of the transmission, if the dog teeth of the dog clutch make contact with a gear, and the two parts are spinning at different speeds, the teeth will fail to engage and a loud grinding sound will be heard as they clatter together. For this reason, a synchronizer mechanism or synchronizer clutch is used, which consists of a cone clutch. Before the teeth engage, the cone clutch engages first, which brings the two rotating elements to the same speed using friction. Until synchronization occurs, the teeth are prevented from making contact. It should be appreciated that the exact design of the synchronizer clutch is within a designer&#39;s choice for satisfying packaging and performance requirements. A synchronizer clutch is optionally configured to be a two position clutch having an engaged position and a neutral (or free) position. A synchronizer clutch is optionally configured to be a three position clutch having a first engaged position, a second engaged position, and a neutral position. Embodiments disclosed herein use synchronizer clutches to enable the pre-selection of gear sets by a control system (not shown) for smooth transition between operating modes of the transmission. It should be appreciated that the powertrain configurations disclosed herein are optionally configured with other types of selectable torque transmitting devices including, and not limited to, wet clutches, dry clutches, dog clutches, and electromagnetic clutches, among others. 
         [0028]    Still referring to  FIG. 4 , in some embodiments, the CVT  10  includes a second gear set  34  configured to couple the second planet carrier  27  to the first-and-third mode clutch  19 . The second gear set  34  includes, for example, two meshing gears, one of which is coaxial with the countershaft  22  and the other coaxial with the main axis. In some embodiments, the CVT  10  includes a reverse clutch  35  arranged coaxially with the countershaft  22 . The reverse clutch  35  is optionally configured as a controllable clutch. For example, during operation of the CVT  10 , the reverse clutch  35  is configured to operate as a bearing during forward direction of operation, and the reverse clutch  35  is configured to operate as a clutching device during reverse direction of operation. In some embodiments, a third gear set  36  operably couples the reverse clutch  35  to the first-and-third-mode clutch  19 . The third gear set  36  optionally includes a number of meshing gears. For example, the third gear set  36  includes a gear arranged coaxially with the countershaft  22 , an idler gear supported on a shaft arranged parallel to the countershaft, and a gear arranged coaxially with the main axis. 
         [0029]    Turning now to  FIG. 5 , during operation of the CVT  10  multiple modes of operation are achieved through engagement of the various clutching devices to provide modes corresponding to overlapping ranges of speed and torque. Typically, the first mode of operation corresponds to a launch mode of a vehicle from a stop. The subsequent modes engaged correspond to higher speed ranges. Likewise, the reverse mode of operation corresponds to a reverse direction of a vehicle equipped with the CVT  10 . The table depicted in  FIG. 5 , lists the modes of operation for the CVT  10  and indicates the corresponding clutch engagement. For mode  1  operation, the first-and-third mode clutch  19  is engaged while the second-and-fourth mode clutch  23  is disengaged. Mode  1  operation corresponds to the first synchronizer clutch  32  engaged in a position to thereby couple the second ring gear  26  and the second planet carrier  27 . During mode  1  operation, the second synchronizer clutch  33  is in a neutral position or controlled to preselect engagement for mode  2  operation. For mode  2  operation, the second-and-fourth mode clutch  23  is engaged while the first-and-third mode clutch  19  is disengaged. Mode  2  operation corresponds to the second synchronizer clutch  33  engaged in a position to thereby couple the third ring gear  29  and the third planet carrier  30 . During mode  2  operation, the first synchronizer clutch  32  is in a neutral position or controlled to preselect engagement for operating in mode  1  or in mode  3 . For mode  3  operation, the first-and-third mode clutch  19  is engaged while the second-and-fourth mode clutch  23  is disengaged. Mode  3  operation corresponds to the first synchronizer clutch  32  engaged in a position to thereby couple the second ring gear  26  to a grounded member. During mode  3  operation, the second synchronizer clutch  33  is in a neutral position or controlled to preselect engagement for mode  2  or mode  4  operation. For mode  4  operation, the second-and-fourth mode clutch  23  is engaged whiled the first-and-third mode clutch  19  is disengaged. Mode  4  operation corresponds to the second synchronizer clutch  33  engaged in a position to thereby couple the third ring gear  29  to a grounded member. During mode  4  operation, the first synchronizer clutch  33  is in a neutral position or controlled to preselect engagement for mode  3  operation. For reverse operation, the first-and-third mode clutch  19  and the reverse clutch  35  are engaged while the second-and-fourth mode clutch  23  is disengaged. The first synchronizer clutch  32  and the second synchronizer clutch  33  are in neutral positions. 
         [0030]    Referring now to  FIGS. 6 and 7 , and still referring to  FIG. 4 , in some embodiments, the first planetary gear set  15  and the variator  12  are collectively referred to as a powersplit variator assembly  37 . It should be appreciated that the powersplit variator assembly  37  is optionally configured to have different couplings between the fixed ratio planetary portion and the variator portion. For example, the powersplit variator assembly  37  is optionally configured such as the power paths described in pending U.S. patent applications Ser. Nos. 15/423,131; 62/291,668; and 62/316,703, each of which are hereby incorporated by reference. During operation of the CVT  10 , power flow through the powersplit variator assembly  37  for mode  1  and mode  3  operation is depicted with dashed arrows in  FIG. 6 . Rotational power comes in on the first rotatable shaft  11  and is transmitted out of the powersplit variator assembly  37  through the first ring gear  16 . Power flow through the powersplit variator assembly  37  for mode  2  and mode  4  operation is depicted with dashed arrows in  FIG. 7 . Rotational power is transmitted on the first rotatable shaft  11  and is transmitted out of the powersplit variator assembly  37  through the second rotatable shaft  20 . 
         [0031]    It should be noted that the description above has provided dimensions for certain components or subassemblies. The mentioned dimensions, or ranges of dimensions, are provided in order to comply as best as possible with certain legal requirements, such as best mode. However, the scope of the embodiments described herein are to be determined solely by the language of the claims, and consequently, none of the mentioned dimensions is to be considered limiting on the inventive embodiments, except in so far as any one claim makes a specified dimension, or range of thereof, a feature of the claim. 
         [0032]    While preferred embodiments have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the preferred embodiments. It should be understood that various alternatives to the embodiments described herein may be employed in practicing the preferred embodiments. It is intended that the following claims define the scope of the preferred embodiments and that methods and structures within the scope of these claims and their equivalents be covered thereby.