Continuously variable transmission

A continuously variable transmission includes an input disk and output disk rotatable about a disk axis of rotation. An input ring member rotatable about an input axis of rotation engages the input disk at an input contact patch. An output ring member rotatable about an output axis of rotation engages the output disk at an output contact patch. A sum of a length of a first input contact patch vector extending from the input contact patch to the disk axis of rotation and a length of a first output contact patch vector extending from the output contact patch to the disk axis of rotation is greater than a length of at least one of a second input contact patch vector extending from the input contact patch to the input axis of rotation and a second output contact patch vector extending from the output contact patch to the output axis of rotation.

RELATED APPLICATIONS

This application claims the benefit of U.S. patent application Ser. No. 14/166,336, filed on Jan. 28, 2014, which is herein incorporated by reference in its entirety.

BACKGROUND

A continuously variable transmission (CVT) is a type of transmission capable of providing more useable power, better fuel economy and a smoother driving experience than a traditional manual or automatic transmission. A typical automotive transmission may include a fixed number of gears from which to select. The transmission may employ a gear-set that provides a given number of gear ratios. The transmission shifts gears in an attempt to provide the most appropriate gear ratio for a given situation. Switching into a particular gear may allow the vehicle to produce near maximum power it can with the least amount of energy.

A continuously variable transmission (CVT) is a transmission capable of changing seamlessly through an infinite number of effective gear ratios between maximum and minimum values. A CVT makes it possible to vary progressively the transmission ratio. This contrasts with other mechanical transmissions that offer a fixed number of gear ratios. A CVT may provide better fuel economy than other transmissions, by enabling the engine to run at its most efficient revolutions per minute (RPM) for a range of vehicle power and speed combinations. A CVT may also be used to maximize the performance of a vehicle by allowing the engine to turn at the RPM at which it produces peak power. This is typically higher than the RPM that achieves peak efficiency. A CVT may create a more fuel efficient vehicle. The nearly unlimited number of positions helps ensure it is always using the appropriate amount of power.

SUMMARY

Disclosed herein is a continuously variable transmission that may include an input disk rotatable about a disk axis of rotation. The input disk may include an input disk traction surface. The continuously variable transmission may also include an output disk rotatable about the disk axis of rotation. The output disk may include an output disk traction surface. An input ring member rotatable about an input axis of rotation may include an input ring traction surface located at an input ring traction surface radial distance from the input axis of rotation. The input ring traction surface may engage the input disk traction surface at an input contact patch oriented substantially perpendicular to a first input contact patch vector length extending from the input contact patch to the disk axis of rotation and a second input contact patch vector length extending perpendicular from the input contact patch to the input axis of rotation. An output ring member rotatable about an output axis of rotation may include an output ring traction surface located at an output ring traction surface radial distance from the output axis of rotation. The output ring traction surface may engage the output disk traction surface at an output contact patch oriented substantially perpendicular to a first output contact patch vector length extending perpendicular from the output contact patch to the disk axis of rotation and a second output contact patch vector length extending from the output contact patch to the output axis of rotation. The sum of a length of the first input contact patch vector and a length of the first output contact patch vector is greater than a length of at least one of the second input contact patch vector and the second output contact patch vector.

DETAILED DESCRIPTION

Referring now to the discussion that follows and also to the drawings, illustrative approaches to the disclosed systems and methods are described in detail. Although the drawings represent some possible approaches, the drawings are not necessarily to scale and certain features may be exaggerated, removed, sectioned out-of-plane or partially sectioned to better illustrate and explain the present invention. Further, the descriptions set forth herein are not intended to be exhaustive or otherwise limit or restrict the claims to the precise forms and configurations shown in the drawings and disclosed in the following detailed description.

With reference toFIG. 1, an exemplary continuously variable transmission40operable for transferring rotational energy between an input shaft42and an output shaft44. The input shaft42is rotatable about an input axis of rotation46and the output shaft44is rotatable about an output axis of rotation48. The input axis of rotation46may be arranged substantially parallel to the output axis of rotation48. The input axis of rotation46may be offset from the output axis of rotation48by a distance50. The input and output shafts42and44, respectively, may each be rotatably supported within a housing52by bearings54. The bearings54may have any of various configurations, including, but not limited to, a roller bearing, ball bearing and a tapered bearing, and may include other configurations. Multiple bearings54and/or bearing types may be used for supporting the input and output shafts42and44. The position and orientation of the input shaft42is generally fixed relative to the output shaft44.

The continuously variable transmission40may include an input drive mechanism56and an output drive mechanism58spaced from the input drive mechanism56. The input and output drive mechanisms56and58may be arranged in series. The input and output drive mechanisms56and58, respectively, operate in conjunction with one another to transfer rotational torque from the input shaft42to the output shaft44. The input and output drive mechanisms56and58may be selectively adjusted to vary a speed ratio (e.g., speed ratio=(rotational speed of output shaft44)÷(rotational speed of input shaft42)) of the continuously variable transmission40. The continuously variable transmission40may employ a speed ratio selector60operable to selectively adjust the speed ratio.

The input drive mechanism56may employ a first input disk62and a second input disk64positioned adjacent the first input disk62. The first and second input disks62and64are each rotatable about a disk axis of rotation66. The disk axis of rotation66may be aligned generally parallel with the input axis of rotation46and/or the output axis of rotation48. The location of the disk axis of rotation66may be selectively adjusted relative to the input axis of rotation46and/or the output axis of rotation48while maintaining the orientation of the disk axis of rotation66relative to the input axis of rotation46and/or the output axis of rotation48. In other words, the disk axis of rotation66remains substantially parallel to the input axis of rotation46and the output axis of rotation48when adjusting the position of the disk axis of rotation66relative to the input axis of rotation42and/or the output axis of rotation44.

The first and second input disks62and64extend generally radially outward from the disk axis of rotation66. An edge67defines an outer circumferential perimeter of the first input disk62. The first input disk62may include a generally convex conically-shaped first input disk traction surface68positioned adjacent input shaft42and an opposite inner surface70positioned adjacent the second input disk64. The inner surface70of the first input disk62may have generally planar surface contour, as illustrated, for example, inFIG. 1, or may include various other shapes and/or contours. For example, the inner surface70may include one or more recessed regions to help minimize weight and/or rotational inertia of the first input disk62.

The first input disk62may be fixedly attached to an inner shaft72that extends latterly outward from the inner surface70of the first input disk62. The first input disk62may alternatively be integrally formed with the inner shaft72. A longitudinal axis of the inner shaft72substantially coincides with the disk axis of rotation66.

With continued reference toFIG. 1, an edge74defines an outer circumferential perimeter of the second input disk64. The second input disk64may include an inner surface76positioned adjacent the first input disk62and a generally convex conically-shaped second input disk traction surface78located opposite the inner surface76. The second input disk64may be generally configured as a mirror image of the first input disk62when viewed from the perspective ofFIG. 1. Similar to first input disk62, the inner surface76of the second input disk64may have generally planar surface contour, as illustrated, for example, inFIG. 1, or may include various other shapes and/or contours. For example, the inner surface76may include one or more recessed regions to help minimize weight and/or rotational inertia of the second input disk64.

The second input disk64may be fixedly attached to a hollow cylindrically-shaped outer shaft80that extends latterly outward from the second input disk traction surface78of the second input disk64. The second input disk64may alternatively be integrally formed with the outer shaft80. A longitudinal axis of the outer shaft80substantially coincides with the disk axis of rotation66. The outer shaft80includes an elongated outer shaft passage82for receiving inner shaft72. The outer shaft passage82extends lengthwise along the disk axis of rotation66. The inner shaft72and outer shaft80are moveable axially relative to one another along the disk axis of rotation66to enable a distance D1between the first input disk traction surface68and the second input disk traction surface68to be selectively varied. The inner shaft72and outer shaft80may be configured so as to be rotatable relative to one another, or may alternatively be rotatably fixed to one another. The latter may be accomplished, for example, through use of a spline that allows axial movement between the inner and outer shafts72and80, while simultaneously preventing the inner and outer shafts72and80from rotating relative to one another. Either way, the inner shaft72and outer shaft80are generally free to move axially relative to one another.

The output drive mechanism58may be similarly configured as the input drive mechanism56, and may include for example, a first output disk84and a second output disk86positioned adjacent the first output disk84. The first and second output disks84and86are each rotatable about the disk axis of rotation66. The first and second output disks84and86extend generally radially outward from the disk axis of rotation66.

An edge88defines an outer circumferential perimeter of the first output disk84. The first output disk84may include a generally convex conically-shaped first output disk traction surface90arranged adjacent output shaft44and an opposite inner surface92positioned adjacent the second output disk86. The inner surface92of the first output disk84may have generally planar surface contour, as illustrated, for example, inFIG. 1, or may include various other shapes and/or contours. For example, the inner surface92may include one or more recessed regions to help minimize weight and/or rotational inertia of the first output disk84.

The first output disk84may be fixedly attached to an end93of inner shaft72opposite the first input disk62, causing the first input disk62and the first output disk84to operably rotate in unison about the disk axis of rotation66. To facilitate assembly, end93of the inner shaft72and first output disk84may include conjoining threads to enable the first output disk84to be threaded onto the inner shaft72. Other fastening mechanisms may also be used to attach the first output disk84to end83of the inner shaft72, such as bolts, rivets, screws, gluing, brazing and welding, to name a few. Alternatively, the first output disk84may be integrally formed with the inner shaft72.

With continued reference toFIG. 1, an edge94defines an outer circumferential perimeter of the second output disk86. The second output disk86may include an inner surface96positioned adjacent the first output disk84and a generally convex conically-shaped second input disk traction surface98located opposite the inner surface96. The second output disk86may be generally configured as a mirror image of the first output disk84when viewed from the perspective ofFIG. 1. Similar to first output disk84, the inner surface96of the second input disk96may have generally planar surface contour, as illustrated, for example, inFIG. 1, or may include various other shapes and/or contours. For example, the inner surface96may include one or more recessed regions to help minimize weight and/or rotational inertia of the second output disk86.

The second output disk86may be fixedly attached to an end100of the outer shaft80, causing the second input disk64and the second output disk86to operably rotate in unison about the disk axis of rotation66. To facilitate assembly, end100of the outer shaft80and second output disk86may include conjoining threads to enable the second output disk86to be threaded onto the outer shaft80. Other fastening mechanisms may also be used to attach the second output disk86to end100of the outer shaft80, such as bolts, rivets, screws, gluing, brazing and welding, to name a few. Alternatively, the second output disk86may be integrally formed with the outer shaft80.

Similar to first input disk62and second input disk64, the first output disk84and the second output disk86are moveable axially relative to one another along the disk axis or rotation66. This enables a distance D2between the first output disk traction surface90and the second output disk traction surface98to be selectively varied.

The input drive mechanism56may include an input ring member102fixedly connected to the input shaft42for concurrent rotation therewith. The input ring member102operates to rotatably couple the first and second input disks62and64to the input shaft42. The position and orientation of the input ring member102remains substantially fixed relative to the input shaft42. The input ring member102may have a generally C-shaped configuration with an open end104arranged opposite a closed end106. The closed end106may be fixedly attached to or integrally formed with the input shaft42. A generally circular opening103in the open end104of the input ring member102is defined by a circumferential edge108.

The first and second input disks62and64may be positioned within an interior cavity110of the input ring member102, with the corresponding inner and outer shafts72and80extending through the opening103in the input ring member102. The opening103may be sized larger than the first and second input disks62and64to facilitate positioning of the disks within the interior cavity110of the input ring member102.

The input ring member102may include an input ring first traction surface112engageable with the first input disk traction surface68of the first input disk62, and an input ring second traction surface114engageable with the second input disk traction surface78. The input ring first and second traction surfaces112and114may be configured as continuous rings extending inward from an inner surface116of the input ring member102. The input ring first and second traction surfaces112and114may be located at a radius117from the input axis of rotation46. The input ring second traction surface114may be arranged immediately adjacent the opening103in the input ring member102. The input ring first traction surface may be located opposite the input ring second traction surface114along a side of the input ring member102attached to the input shaft42.

The output drive mechanism58may include an output ring member118fixedly connected to the output shaft44for concurrent rotation therewith. The output ring member118operates to rotatably couple the first and second output disks84and86to the output shaft44. The position and orientation of the output ring member118remains substantially fixed relative to the output shaft44. The output ring member118may have a generally C-shaped configuration with an open end120arranged opposite a closed end122. The closed end122may be fixedly attached to or integrally formed with the output shaft44. A generally circular opening124in the open end120of the output ring member118is defined by a circumferential edge126.

The first and second output disks84and86may be positioned within an interior cavity130of the output ring member118, with the corresponding inner and outer shafts72and80extending through the opening124in the output ring member118. The opening124may be sized larger than the first and second output disks84and86to facilitate positioning of the disks within the interior cavity130of the output ring member118.

The output ring member118may include an output ring first traction surface132engageable with the first output disk traction surface90of the first output disk84, and an output ring second traction surface134engageable with the second output disk traction surface98. The output ring first and second traction surfaces132and134may be configured as a continuous ring extending generally inward from an inner surface138of the output ring member118. The output ring first and second traction surfaces132and134may be located at a radius136from the output axis of rotation48. The output ring second traction surface134may be arranged immediately adjacent the opening124in the output ring member118. The output ring first traction surface132may be located opposite the output ring second traction surface134along a side of the output ring member118attached to the output shaft44.

The continuously variable transmission40operates to transfer torque from the input shaft42to the output shaft44. Torque from the input shaft42may be transmitted from the input ring member102to the first input disk62across a first input contact patch140where the input ring first traction surface112engages the first input disk traction surface78, and to the second input disk64across a second input contact patch142where the input ring second traction surface114engages the second input disk traction surface78. The first and second input contact patches140and142are located at a radius143from the disk axis of rotation66. The radius143of the first and second input contact patches140and142varies as the speed ratio of the continuously variable transmission40is varied. The inner shaft72transfers torque from the first input disk62to the first output disk84. The outer shaft80transfers torque from the second input disk64to the second output disk86. Torque may be transferred from the first output disk84to the output ring member118across a first output contact patch144where the output ring first traction surface132engages the first output disk traction surface90. Torque may be transferred from the second output disk86to the output ring member118across a second output contact patch146where the output ring second traction surface134engages the second output disk traction surface134. The first and second output contact patches144and146are located at a radius147from the disk axis of rotation66. It should be noted that for purposes of discussion the first and second contact patches144and146are illustrated as occurring within a common plane, so as to be arranged on diametrically opposite sides of disk axis of rotation66(i.e., approximately 180 degrees apart). In practice, however, first and second contact patches144and146may be located out-of-plane, such that the angular location of the first and second contact patches relative to one another is something other than 180 degrees. The radius147of the first and second output contact patches144and146varies as the speed ratio of the continuously variable transmission40is varied. The output ring member118operates to transfer torque from the first and second output disks84and86to the output shaft44.

The speed ratio of the continuously variable transmission40is a function of the radial location143of the first and second input contact patches140and142, and the radial location147of the first and second output contact patches144and146. The speed ratio of the continuously variable transmission40is partially determined by the radial location at which the input ring first and second traction surfaces112and114engage the first and second input disk traction surfaces68and78, respectively (i.e., the radial location143of the first and second input contact patches140and142). The rotational speed of the output shaft44decreases, relative to the rotational speed of the input shaft42, as the radial location143of the first and second input contact patches140and142increases. On the other hand, the rotational speed of the output shaft44increases as the radial location143of the first and second input contact patches140and142decreases. The radial location at which the output ring first and second traction surfaces132and134engage the first and second output disk traction surfaces90and98, respectively (i.e., the radial location147of the first and second output contact patches144and146) has the opposite effect. The rotational speed of the output shaft44increases, relative to the rotational speed of the input shaft42, as the radial location147of the first and second output contact patches144and146increases. On the other hand, the rotational speed of the output shaft44decreases as the radial location147of the first and second output contact patches144and146decreases.

The speed ratio may be selectively adjusted by moving the location of the disk axis of rotation66relative to the input axis of rotation46and the output axis of rotation48, which effects the radial location143at which the input ring member102engages the first and second input disks62and64, and the radial location147at which the output ring member118engages the first and second output disks84and86. Since the first input disk46is connected to the first output disk84by way of inner shaft72, and the second input disk64is connected to the second output disk86by way of outer shaft80, any movement of the first and second input disks62and64results in corresponding movement of the first and second output disks84and86. For example, moving the first and second input disks62and64radially upward (as viewed from the perspective ofFIG. 1) also moves the first and second output disks radially upward. On the other hand, moving the first and second input disks62and64radially downward (as viewed from the perspective ofFIG. 1) also moves the first and second output disks radially downward.

With reference toFIG. 2, the first input contact patch140is aligned substantially perpendicular to a first input contact patch vector154extending from the first input contact patch140to the disk axis of rotation66, and aligned substantially perpendicular to a second input contact patch vector length156extending from the first input contact patch140to the input axis of rotation46. Similarly, the first output contact patch146is aligned substantially perpendicular to a first output contact patch vector158extending from the first output contact patch146to the disk axis of rotation66, and aligned substantially perpendicular to a second output contact patch vector160extending from the first output contact patch146to the output axis of rotation48. The configuration and arrangement of the various components of the continuously variable transmission40is such that a sum of a length of the first input contact patch vector154and a length of the first output contact patch vector158is greater than a length of the second input contact patch vector156and a length of the second output contact patch vector160. The following relationship holds true for all speed ratios:
((length of first input contact patch vector 154)+(length of first output contact patch vector 158))>(length of second input contact patch vector 156); and  A.
((length of first input contact patch vector 154)+(length of first output contact patch vector 158))>(length of second output contact patch vector 160)  B.

A similar relationship also holds true for the second input contact patch142and the second output contact patch144. For example, a sum of a length of a first input contact patch vector extending from the second input contact patch142to the disk axis of rotation66and aligned substantially perpendicular to the second input contact patch142, and a length of a first output contact patch vector extending from the second output contact patch146to the disk axis of rotation66and aligned substantially perpendicular to the second output contact patch146is greater than at least one of a length of a second input contact patch vector extending from the second input contact patch142to the input axis of rotation46and aligned substantially perpendicular to the second output contact patch142, and a length of a second output contact patch vector extending from the second output contact patch146to the output axis of rotation48and aligned substantially perpendicular to the second output contact patch146.

With reference toFIGS. 1 and 3-5, the speed ratio selector60may be used to selectively adjust the speed ratio of the continuously variable transmission40. The speed ratio selector60may have any of a wide variety of configurations. The speed ratio selector60may employ any device capable of adjusting a location of the first and second input disks62and64relative to the input ring102and the first and second output disks84and86relative to the output ring118. This may be accomplished, for example, by selectively adjusting the location of the disk axis of rotation66relative to the input axis of rotation46and/or the output axis of rotation48. An example of one possible configuration of the speed ratio selector60is illustrated in the drawing figures. The speed ratio selector60may include, for example, a pair of interconnected links operably connecting the outer shaft80, and correspondingly, the inner shaft72, the first and second input disks62and64, and the first and second output disks84and86, to the housing52. The speed ratio selector60operates to vary the location of the disk axis of rotation66relative to the input axis of rotation46and output axis of rotation48, and thus the speed ratio. The speed ratio selector60may include a first link148pivotally attached to the outer shaft80and a second link150pivotally attached to the first link148and the housing52. The speed ratio selector60may employ one or more bearings152located at the pivot points of the speed ratio selector60. The speed ratio may be varied by alternately collapsing and extending the first and second links148and150, which varies a distance between the disk axis of rotation66and the housing52, and correspondingly, the location of the disk axis of rotation66relative to the input axis of rotation46and the output axis of rotation48.

FIGS. 1 and 3illustrate the speed ratio selector60arranged in a first speed ratio position, in which the first and second links148and150are fully extended. In this position the input ring member102engages the first and second input disks62and64near their respective outer edges67and74, and the output ring member118engages the first and second output disks84and86closer toward the disk axis of rotation66. This arrangement produces the lowest speed ratio (e.g., speed ratio=(rotational speed of output shaft44)÷(rotational speed of input shaft42)), wherein the output shaft44has a lower rotational speed than the input shaft42.

FIGS. 4 and 5illustrate the speed ratio selector60arranged in a second speed ratio position, in which the first and second links148and150are fully collapsed. In this position the output ring member118engages the first and second output disks84and86near their respective outer edges88and94, and the input ring member102engages the first and second input disks62and64closer toward the disk axis of rotation66. This arrangement produces the highest speed ratio, wherein the output shaft44has a lower rotational speed than the input shaft42. The speed ratio selector60may be infinitely adjustable between the first speed ratio position (for example, as illustrated inFIGS. 1 and 3) and the second speed ratio position (for example, as illustrated inFIGS. 4 and 5).

The speed ratio selector60illustrated in the drawing figures is merely one example of the various types and configuration of actuators that may be used to selectively adjust the speed ratio of the continuously variable transmission. Other types and configurations of actuating mechanisms may also be employed. For example, the speed ratio selector60may include electro-mechanical, hydraulic, pneumatic and mechanical actuators, as well as combinations thereof. Other mechanisms capable of selectively adjusting the radial location of the first and second input disks62and64relative to the input ring member102, and the radial location of the first and second output disks84and86relative to the output ring member118, may also be employed for selectively adjusting the speed ratio of the continuously variable transmission40.

With reference toFIG. 6, an alternately configured continuously variable transmission200operable for transferring rotational energy between the input shaft42and the output shaft44. The input shaft42is rotatable about the input axis of rotation46and the output shaft44is rotatable about an output axis of rotation48. The input axis of rotation46may be arranged substantially parallel to the output axis of rotation48. The input axis of rotation46may be offset from the output axis of rotation48by the distance50. The input and output shafts42and44, respectively, may each be rotatably supported within the housing52by bearings54. The position and orientation of the input shaft42is generally fixed relative to the output shaft44. The offset distance50may be used to compensate for variation in working fluid viscosity.

The continuously variable transmission200may include an input drive mechanism202and an output drive mechanism204spaced from the input drive mechanism202. The input and output drive mechanisms202and204, respectively, operate in conjunction with one another to transfer rotational torque from the input shaft42to the output shaft44. The input and output drive mechanisms202and204may be arranged in series. The input and output drive mechanisms202and204may be selectively adjusted to vary the speed ratio (e.g., speed ratio=(rotational speed of output shaft44)÷(rotational speed of input shaft42)) of the continuously variable transmission200. The continuously variable transmission200may employ the speed ratio selector60operable to selectively adjust the speed ratio.

The input drive mechanism202may employ a first input disk206and a second input disk208positioned adjacent the first input disk206. The first and second input disks206and208are each rotatable about a disk axis of rotation210. The disk axis of rotation210may be aligned generally parallel with the input axis of rotation46and/or the output axis of rotation48. The location of the disk axis of rotation210may be selectively adjusted relative to the input axis of rotation46and/or the output axis of rotation48while maintaining the orientation of the disk axis of rotation210relative to the input axis of rotation46and/or the output axis of rotation48. In other words, the disk axis of rotation210remains substantially parallel to the input axis of rotation46and the output axis of rotation48when adjusting the position of the disk axis of rotation210relative to the input axis of rotation42and/or the output axis of rotation44.

The first and second input disks206and208extend generally radially outward from the disk axis of rotation210. An edge212defines an outer circumferential perimeter of the first input disk206. The first input disk206may include a generally convex conically-shaped first input disk traction surface214positioned opposite the input shaft42and adjacent the second input disk208. Opposite the input disk traction surface214is an outer surface216positioned adjacent the input shaft42. The outer surface216of the first input disk206may have generally planar surface contour, as illustrated, for example, inFIG. 6, or may include various other shapes and/or contours. For example, the inner surface216may include one or more recessed regions to help minimize weight and/or rotational inertia of the first input disk206.

The first input disk206may be fixedly attached to an inner shaft218that extends laterally outward from the first input disk traction surface214of the first input disk206. The first input disk206may alternatively be integrally formed with the inner shaft218. A longitudinal axis of the inner shaft218substantially coincides with the disk axis of rotation210.

With continued reference toFIG. 6, an edge220defines an outer circumferential perimeter of the second input disk208. The second input disk208may include a generally convex conically-shaped second input disk traction surface222positioned adjacent the first input disk206and an outer surface224located opposite the second input disk traction surface222. The second input disk208may be generally configured as a mirror image of the first input disk206when viewed from the perspective ofFIG. 6. Similar to first input disk206, the outer surface224of the second input disk208may have generally planar surface contour, as illustrated, for example, inFIG. 6, or may include various other shapes and/or contours. For example, the outer surface224may include one or more recessed regions to help minimize weight and/or rotational inertia of the second input disk208.

The second input disk208may be fixedly attached to a hollow cylindrically-shaped outer shaft226that extends latterly outward from the outer surface224of the second input disk208. The second input disk208may alternatively be integrally formed with the outer shaft226. A longitudinal axis of the outer shaft226substantially coincides with the disk axis of rotation210. The outer shaft226includes an elongated outer shaft passage228for receiving inner shaft218. The outer shaft passage226extends lengthwise along the disk axis of rotation210. The inner shaft218and outer shaft226are moveable axially relative to one another along the disk axis of rotation210to enable a distance D1between the first input disk traction surface214and the second input disk traction surface22to be selectively varied. The inner shaft218and outer shaft226may be configured so as to be rotatable relative to one another, or may alternatively be rotatably fixed to one another. The latter may be accomplished, for example, through use of a spline that allows axial movement of the inner and outer shafts218and226relative to one another, while simultaneously preventing the inner and outer shafts218and226from rotating relative to one another. Either way, the inner shaft218and outer shaft226are generally free to move axially relative to one another.

The output drive mechanism204may be similarly configured as the input drive mechanism202, and may include for example, a first output disk230and a second output disk232positioned adjacent the first output disk230. The first and second output disks230and232are each rotatable about the disk axis of rotation210. The first and second output disks230and232extend generally radially outward from the disk axis of rotation210.

An edge234defines an outer circumferential perimeter of the first output disk230. The first output disk230may include a generally convex conically-shaped first output disk traction surface236arranged opposite the output shaft44and an adjacent the second output disk232. An outer surface238of the first output disk230may have a generally planar surface contour, as illustrated, for example, inFIG. 6, or may include various other shapes and/or contours. For example, the outer surface238may include one or more recessed regions to help minimize weight and/or rotational inertia of the first output disk230.

The first output disk230may be fixedly attached to an end240of inner shaft218opposite the first input disk206, causing the first input disk206and the first output disk230to operably rotate in unison about the disk axis of rotation210. To facilitate assembly, end240of the inner shaft218and the first output disk230may include conjoining threads to enable the first output disk230to be threaded onto the inner shaft218. Other fastening mechanisms may also be used to attach the first output disk230to end240of the inner shaft218, such as bolts, rivets, screws, gluing, brazing and welding, to name a few. Alternatively, the first output disk230may be integrally formed with the inner shaft218.

With continued reference toFIG. 6, an edge242defines an outer circumferential perimeter of the second output disk232. The second output disk232may include a generally convex conically-shaped second input disk traction surface244positioned adjacent the first output disk230and located opposite an outer surface246. The second output disk232may be generally configured as a mirror image of the first output disk230when viewed from the perspective ofFIG. 6. Similar to the first output disk230, the outer surface246of the second input disk232may have generally planar surface contour, as illustrated, for example, inFIG. 6, or may include various other shapes and/or contours. For example, the outer surface246may include one or more recessed regions to help minimize weight and/or rotational inertia of the second output disk232.

The second output disk232may be fixedly attached to an end248of the outer shaft226, causing the second input disk208and the second output disk232to operably rotate in unison about the disk axis of rotation210. To facilitate assembly, end248of the outer shaft226and the second output disk232may include conjoining threads to enable the second output disk232to be threaded onto the outer shaft226. Other fastening mechanisms may also be used to attach the second output disk232to end248of the outer shaft226, such as bolts, rivets, screws, gluing, brazing and welding, to name a few. Alternatively, the second output disk232may be integrally formed with the outer shaft226.

Similar to first input disk206and second input disk208, the first output disk230and the second output disk232are moveable axially relative to one another along the disk axis or rotation210. This enables a distance D2between the first output disk traction surface236and the second output disk traction surface244to be selectively varied.

The input drive mechanism202may include an input ring member250fixedly connected to the input shaft42for concurrent rotation therewith. The input ring member250operates to rotatably couple the first and second input disks206and208to the input shaft42. The position and orientation of the input ring member250remains substantially fixed relative to the input shaft42. The input ring member250may have a generally C-shaped configuration with an open end254arranged opposite a closed end256. The closed end256may be fixedly attached to or integrally formed with the input shaft42. A generally circular opening252in the open end254of the input ring member250is defined by a circumferential edge258.

The first input disk206may be positioned within an interior cavity260of the input ring member250, with the inner shaft218extending through the opening252in the input ring member250. The opening252may be sized larger than the first input disk206to facilitate positioning of the disk within the interior cavity260of the input ring member250. The second input disk208may be positioned outside of the input ring member250adjacent the opening252.

The input ring member250may include an input ring first traction surface262engageable with the first input disk traction surface214of the first input disk206, and an input ring second traction surface264engageable with the second input disk traction surface222. The input ring first and second traction surfaces262and264may be configured as a continuous ring. The input ring first and second traction surfaces262and264may be located at a radius265from the input axis of rotation46. The input ring first and second traction surfaces262and264may be arranged immediately adjacent the opening252in the input ring member250. The input ring first and second traction surfaces262and264generally face in opposite directions, with the first input ring traction surface262extending generally inward toward the interior cavity260and the second input traction surface264extending generally outward and away from the interior cavity260.

The output drive mechanism204may include an output ring member266fixedly connected to the output shaft44for concurrent rotation therewith. The output ring member266operates to rotatably couple the first and second output disks230and232to the output shaft44. The position and orientation of the output ring member266remains substantially fixed relative to the output shaft44. The output ring member266may have a generally C-shaped configuration with an open end268arranged opposite a closed end270. The closed end270may be fixedly attached to or integrally formed with the output shaft44. A generally circular opening272in the open end270of the output ring member266is defined by a circumferential edge274.

The first output disk230may be positioned within an interior cavity276of the output ring member266, with the inner shaft218extending through the opening268in the output ring member266. The opening268may be sized larger than the first output disk230to facilitate positioning of the disk within the interior cavity276of the output ring member266. The second output disk232may be positioned outside of the output ring member266adjacent the opening268.

The output ring member266may include an output ring first traction surface278engageable with the first output disk traction surface236of the first output disk230, and an output ring second traction surface280engageable with the second output disk traction surface244. The output ring first and second traction surfaces278and280may be configured as a continuous ring. The output ring first and second traction surfaces278and280may be located at a radius281from the input axis of rotation46. The output ring first and second traction surfaces278and280may be arranged immediately adjacent the opening268in the output ring member266. The output ring first and second traction surfaces278and280generally face in opposite directions, with the first output ring traction surface278extending generally inward toward the interior cavity276and the second output traction surface280extending generally outward and away from the interior cavity276.

With reference toFIG. 6, the continuously variable transmission200operates to transfer torque from the input shaft42to the output shaft44. Torque from the input shaft42may be transmitted from the input ring member250to the first input disk206across a first input contact patch282where the input ring first traction surface262engages the first input disk traction surface214, and to the second input disk208across a second input contact patch284where the input ring second traction surface264engages the second input disk traction surface222. The first and second input contact patches282and284are located at a radius285from the disk axis of rotation210. The radius285of the first and second input contact patches282and284varies as the speed ratio of the continuously variable transmission200is varied. The inner shaft218transfers torque from the first input disk206to the first output disk230. The outer shaft226transfers torque from the second input disk208to the second output disk232. Torque may be transferred from the first output disk230to the output ring member266across a first output contact patch286where the output ring first traction surface278engages the first output disk traction surface236. Torque may be transferred from the second output disk232to the output ring member266across a second output contact patch288where the output ring second traction surface280engages the second output disk traction surface244. The first and second output contact patches286and288are located at a radius289from the disk axis of rotation210. The radius289of the first and second output contact patches286and288varies as the speed ratio of the continuously variable transmission200is varied. The output ring member266operates to transfer torque from the first and second output disks230and232to the output shaft44.

The speed ratio of the continuously variable transmission200is a function of the radial location285of the first and second input contact patches282and284, and the radial location289of the first and second output contact patches286and288. The speed ratio of the continuously variable transmission200is partially determined by the radial location at which the input ring first and second traction surfaces262and264engage the first and second input disk traction surfaces214and222, respectively (i.e., the radial location285of the first and second input contact patches282and284). The rotational speed of the output shaft44decreases, relative to the rotational speed of the input shaft42, as the radial location285of the first and second input contact patches282and284increases. On the other hand, the rotational speed of the output shaft44increases as the radial location285of the first and second input contact patches282and284decreases. The radial location at which the output ring first and second traction surfaces278and280engage the first and second output disk traction surfaces236and244, respectively (i.e., the radial location289of the first and second output contact patches286and288) has the opposite effect. The rotational speed of the output shaft44increases, relative to the rotational speed of the input shaft42, as the radial location289of the first and second output contact patches286and288decreases. On the other hand, the rotational speed of the output shaft44decreases as the radial location289of the first and second output contact patches286and288increases.

The speed ratio may be selectively adjusted by moving the location of the disk axis of rotation210relative to the input axis of rotation46and/or the output axis of rotation48, which effects the radial location285at which the input ring member250engages the first and second input disks206and208, and the radial location289at which the output ring member266engages the first and second output disks230and232. Since the first input disk206is connected to the first output disk230by way of inner shaft218, and the second input disk208is connected to the second output disk232by way of outer shaft226, any movement of the first and second input disks206and208results in corresponding movement of the first and second output disks230and232. For example, moving the first and second input disks206and208radially upward (as viewed from the perspective ofFIG. 6) also moves the first and second output disks230and232radially upward. On the other hand, moving the first and second input disks206and208radially downward (as viewed from the perspective ofFIG. 6) also moves the first and second output disks230and232radially downward.

With reference toFIG. 7, the second input contact patch284is aligned substantially perpendicular to a first input contact patch vector290extending from the second input contact patch284to the disk axis of rotation210, and aligned substantially perpendicular to a second input contact patch vector292extending from the second input contact patch284to the input axis of rotation46. Similarly, the second output contact patch286is aligned substantially perpendicular to a first output contact patch vector294extending from the first output contact patch286to the disk axis of rotation210, and aligned substantially perpendicular to a second output contact patch vector296extending from the second output contact patch286to the output axis of rotation48. The configuration and arrangement of the various components of the continuously variable transmission200is such that a sum of a length of the first input contact patch vector290and a length of the first output contact patch vector294is greater than a length of the second input contact patch vector292and a length of the second output contact patch vector296. The following relationship holds true for all speed ratios:
((length of first input contact patch vector 290)+(length of first output contact patch vector 294))>(length of second input contact patch vector 292); and  A.
((length of first input contact patch vector 290)+(length of first output contact patch vector 294))>(length of second output contact patch vector 296)  B.

A similar relationship also holds true for the first input contact patch282and the first output contact patch288. For example, a sum of a length of a first input contact patch vector length extending from the first input contact patch282to the disk axis of rotation210and aligned substantially perpendicular to the first input contact patch282, and a length of a first output contact patch vector length extending from the first output contact patch288to the disk axis of rotation66and aligned substantially perpendicular to the first output contact patch288is greater than at least one of a length of a second input contact patch vector length extending from the first input contact patch282to the input axis of rotation46and aligned substantially perpendicular to the first input contact patch282, and a length of a second output contact patch vector length extending from the first output contact patch288to the output axis of rotation48and aligned substantially perpendicular to the first output contact patch288.

The speed ratio selector60may be used to selectively adjust the speed ratio of the continuously variable transmission200. The speed ratio selector60may be configured as previously described in connection withFIGS. 1 and 3-5.FIGS. 6 and 8illustrate the speed ratio selector60arranged in a second speed ratio position, in which the first and second links148and150are fully extended. In this position the input ring member250engages the first and second input disks206and208near their respective outer edges212and220, and the output ring member266engages the first and second output disks230and232closer toward the disk axis of rotation210. This arrangement produces the highest speed ratio (e.g., speed ratio=(rotational speed of output shaft44)÷(rotational speed of input shaft42)), wherein the output shaft44has a higher rotational speed than the input shaft42.

FIGS. 9 and 10illustrate the speed ratio selector60arranged in a first speed ratio position, in which the first and second links148and150are fully collapsed. In this position the output ring member266engages the first and second output disks230and232near their respective outer edges234and242, and the input ring member250engages the first and second input disks206and208closer toward the disk axis of rotation210. This arrangement produces the lowest speed ratio, wherein the output shaft44has a lower rotational speed than the input shaft42. The speed ratio selector60may be infinitely adjustable between the first speed ratio position (for example, as illustrated inFIGS. 6 and 8) and the second speed ratio position (for example, as illustrated inFIGS. 9 and 10).

With reference toFIG. 11, an alternately configured continuously variable transmission300operable for transferring rotational energy between the input shaft42and the output shaft44. The input shaft42is rotatable about the input axis of rotation46and the output shaft44is rotatable about an output axis of rotation48. The input axis of rotation46may be arranged substantially parallel to the output axis of rotation48. The position and orientation of the input shaft42is generally fixed relative to the output shaft44.

The continuously variable transmission300may include an input drive mechanism302and an output drive mechanism304spaced from the input drive mechanism302. The input and output drive mechanisms302and304may be arranged in series. The input and output drive mechanisms302and304, respectively, operate in conjunction with one another to transfer rotational torque from the input shaft42to the output shaft44.

The input drive mechanism302may employ a first input disk306and a second input disk308positioned adjacent the first input disk306. The first input disk306may be fixedly attached to the input shaft42. The second input disk308may be fixedly attached to a hollow cylindrically-shaped input outer shaft326that extends laterally outward from the second input disk308. The first and second input disks306and308are each rotatable about an input disk axis of rotation310. The input disk axis of rotation310substantially coincides with a longitudinal axis of the input shaft42and the input outer shaft326. The input shaft42and the input outer shaft326may be rotatably supported within the housing52by one or more bearings54.

The first and second input disks306and308extend generally radially outward from the input disk axis of rotation310. An edge312defines an outer circumferential perimeter of the first input disk306. The first input disk306may include a generally convex conically-shaped first input disk traction surface314positioned adjacent the second input disk308. An edge320defines an outer circumferential perimeter of the second input disk308. The second input disk308may include a generally convex conically-shaped second input disk traction surface322positioned adjacent the first input disk306. The second input disk308may be generally configured as a mirror image of the first input disk306when viewed from the perspective ofFIG. 11.

The axial location of the input outer shaft326and the second input disk308may be axially fixed relative to the housing52. The input shaft42and the first input disk306may be moveable axially along the input disk axis of rotation310relative to the second input disk306to enable the distance D1between the first input disk traction surface314and the second input disk traction surface322to be selectively varied. Alternatively, the axially location of the input shaft42and the first input disk306may be axially fixed relative to the input outer shaft326and the second input disk308, and the input outer shaft326and the second input disk308may be moveable axially along the input disk axis of rotation310relative to the input shaft42and the first input disk306.

An input biasing mechanism329may be operably connected to the input shaft42. The input biasing mechanism329operates to urge the first input disk306toward the second input disk308. Various biasing mechanisms may be employed, which may include for example, a spring, such as a coil spring, and various hydraulic, mechanical, electro-mechanical devices capable of generating a biasing force.

The input shaft42and input outer shaft326may be configured so as to be rotatable relative to one another, or alternatively rotatably fixed to one another. The latter may be accomplished, for example, by employing a spline that enables axial movement of the input shaft42and the input outer shaft326relative to one another, while simultaneously preventing the input shaft42and input outer shaft326from rotating relative to one another. Either way, the input shaft42and input outer shaft326are generally free to move axially relative to one another.

The output drive mechanism304may be similarly configured as the input drive mechanism302, and may include for example, a first output disk330and a second output disk332positioned adjacent the first output disk330. The first and second output disks330and332are each rotatable about an output disk axis of rotation328. The first output disk330may be fixedly attached to the output shaft44. The second output disk332may be fixedly attached to a hollow cylindrically-shaped output outer shaft333that extends latterly outward from the second output disk332. The output disk axis of rotation328substantially coincides with a longitudinal axis of the output shaft44and the output outer shaft333. The output shaft44and the output outer shaft333may be rotatably supported within the housing52by one or more bearings54.

The first and second output disks330and332extend generally radially outward from the output disk axis of rotation328. An edge334defines an outer circumferential perimeter of the first output disk330. The first output disk330may include a generally convex conically-shaped first output disk traction surface336arranged adjacent the second output disk332. An edge338defines an outer circumferential perimeter of the second output disk332. The second output disk332may include a generally convex conically-shaped second output disk traction surface340positioned adjacent the first input disk330. The second output disk332may be generally configured as a mirror image of the first output disk330when viewed from the perspective ofFIG. 11.

An axial location of the second output disk332may be substantially fixed relative to the housing52. The output shaft44may be moveable axially along the output disk axis of rotation328relative to the output outer shaft333and the first output disk330to enable the distance D2between the first output disk traction surface336and the second output disk traction surface340to be selectively varied. Alternatively, the axially location of the output shaft44may be axially fixed relative to the housing52, and the output outer shaft333and second output disk332may be moveable axially along the output disk axis of rotation328relative to the output shaft44and the first output disk330.

An output biasing mechanism341may be operably connected to the output shaft44. The output biasing mechanism341operates to urge the first output disk330toward the second output disk332. Various biasing mechanisms may be employed, which may include for example, a spring, such as a coil, and various hydraulic, mechanical, electro-mechanical devices capable of generating a biasing force.

The output shaft44and output outer shaft333may be configured so as to be rotatable relative to one another, or alternatively rotatably fixed to one another. The latter may be accomplished, for example, by employing a spline that permits axial movement of the output shaft44and the input outer shaft333relative to one another, while simultaneously preventing the output shaft44and output outer shaft333from rotating relative to one another. Either way, the output shaft44and output outer shaft333are generally free to move axially relative to one another.

The continuously variable drive mechanism300may include a ring member342operably connecting the input drive mechanism302to the output drive mechanism304. The ring member342may be moved radially relative to the input drive mechanism302and the output drive mechanism304. The radial location of the ring member342may be selectively adjusted relative to the input and output drive mechanisms302and304to vary the speed ratio (e.g., speed ratio=(rotational speed of output shaft44)÷(rotational speed of input shaft42)) of the continuously variable transmission300.

A speed ratio selector344may be operably connected to the ring member342to selectively adjust the speed ratio of the continuously variable transmission300. The speed ratio selector344operates to adjust the radial location of the ring member342relative to the input and output drive mechanisms302and304to achieve a selected speed ratio. The speed ratio selector344may have any of a wide variety of configurations. The speed ratio selector344may employ any device capable of adjusting a location of the ring member342relative to the first and second input disks306and308of the input drive mechanism302, and the first and second output disks330and332of the output drive mechanism304.

The ring member342may include a pair of interconnected co-rotating rings. The co-rotating rings may include an input traction ring346that engages the first and second input disks306and308, and an output traction ring348that engages the first and second output disks330and332. A generally cylindrical-shaped connecting ring350may fixedly connect the input traction ring346to the output traction ring348. The input and output traction rings346and348may be arranged substantially perpendicular to the input and output disk access of rotation328and310.

The input traction ring346may include a first traction surface352engageable with the first input disk traction surface314of the first input disk306, and a second traction surface354engageable with the second input disk traction surface308. The input traction ring first and second traction surfaces352and354may be configured as a continuous ring. The input traction ring first and second traction surfaces352and354may be located at a radius356from a ring member axis of rotation355. The input traction ring first and second traction surfaces352and354are arranged on opposite sides of the input traction ring346, with the first traction surface352facing the first input disk306and the second traction surface354facing the second input disk308.

The output traction ring348may include a first traction surface358engageable with the first output disk traction surface336of the first output disk330, and a second traction surface360engageable with the second output disk traction surface340. The output traction ring first and second traction surfaces358and360may be configured as a continuous ring. The output traction ring first and second traction surfaces358and360may be located at a radius362from the ring member axis of rotation355. The output traction ring first and second traction surfaces358and360are arranged on opposite sides of the output traction ring348, with the first traction surface358facing the first output disk330and the second traction surface360facing the second output disk332.

The continuously variable transmission300operates to transfer torque from the input shaft42to the output shaft44. Torque from the input shaft42may be transferred from the first input disk306to the ring member342across a first input contact patch364where the input traction ring first traction surface352engages the first input disk traction surface314. For configurations in which the input shaft42is rotatably fixed to the input outer shaft326, for example, by means of spline, torque from the input shaft42may be transferred to the ring member342across a second input contact patch366where the input traction ring second traction surface354engages the second input disk traction surface322. The first and second input contact patches364and366are located at a radius368from the input disk axis of rotation310. The radius368of the first and second input contact patches364and366varies as the speed ratio of the continuously variable transmission300is varied.

The ring member342transfers torque from the input drive mechanism302to the output drive mechanism304. Torque may be transferred from the ring member342to the first output disk330across a first output contact patch370where the output traction ring first traction surface358engages the first output disk traction surface336. Torque may be transferred from the ring member342to the second output disk332across a second output contact patch372where the output traction ring second traction surface360engages the second output disk traction surface340. The first and second output contact patches370and372are located at a radius374from the output disk axis of rotation328. The radius374of the first and second output contact patches370and372varies as the speed ratio of the continuously variable transmission300is varied. Torque transferred from the ring member342to first output disk330may be output through the output outer shaft333.

For configurations in which the output shaft44is rotatably fixed to the output outer shaft333, for example, by means of spline, torque from the output outer shaft333may be transferred across the connection between the two shafts to the output shaft44. Alternatively, torque from the output shaft44may be transferred across the connection between the two shafts to the output outer shaft333.

The speed ratio of the continuously variable transmission300is a function of the radial location368of the first and second input contact patches364and366, and the radial location374of the first and second output contact patches370and372. The speed ratio of the continuously variable transmission300is partially determined by the radial location at which the input traction ring first and second traction surfaces352and354engage the first and second input disk traction surfaces314and322, respectively (i.e., the radial location368of the first and second input contact patches364and366). The rotational speed of the output shaft44increases, relative to the rotational speed of the input shaft42, as the radial location368of the first and second input contact patches364and366increases. On the other hand, the rotational speed of the output shaft44decreases as the radial location368of the first and second input contact patches364and366decreases. The radial location at which the output traction ring first and second traction surfaces370and372engage the first and second output disk traction surfaces336and340, respectively (i.e., the radial location374of the first and second output contact patches370and372) has the opposite effect. The rotational speed of the output shaft44increases, relative to the rotational speed of the input shaft42, as the radial location374of the first and second output contact patches370and372decreases. On the other hand, the rotational speed of the output shaft44decreases as the radial location374of the first and second output contact patches370and372increases.

The speed ratio may be selectively adjusted by moving the location of the ring member axis of rotation355relative to the input disk axis of rotation310and/or the output disk axis of rotation328, which effects the radial location368at which the ring member342engages the first and second input disks306and308, and the radial location374at which the ring member342engages the first and second output disks330and332. Moving the ring member342radially relative to the first and second input disks304and306results in corresponding movement of the ring member342relative to the first and second output disks330and332. For example, moving the ring member342radially outward relative to the first and second input disks306and308also moves the ring member342radially inward relative to the first and second output disks330and332. On the other hand, moving the ring member342radially inward relative to the first and second input disks306and308also moves the ring member342radially outward relative to the first and second output disks330and332.

With continued reference toFIG. 11, the first input contact patch364is aligned substantially perpendicular to a first input contact patch vector376extending from the first input contact patch364to the input disk axis of rotation310, and aligned substantially perpendicular to a second input contact patch vector378extending from the first input contact patch364to the ring member axis of rotation355. Similarly, the first output contact patch370is aligned substantially perpendicular to a first output contact patch vector380extending from the first output contact patch370to the output disk axis of rotation328, and aligned substantially perpendicular to a second output contact patch vector382extending from the first output contact patch370to the ring member axis of rotation355. The configuration and arrangement of the various components of the continuously variable transmission300is such that a sum of a length of the first input contact patch vector376and a length of the first output contact patch vector380is greater than a length of the second input contact patch vector378and a length of the second output contact patch vector382. The following relationship holds true for all speed ratios:
((length of first input contact patch vector 376)+(length of first output contact patch vector 380))>(length of second input contact patch vector 378); and  A.
((length of first input contact patch vector 376)+(length of first output contact patch vector 380))>(length of second output contact patch vector 382)  B.

A similar relationship also holds true for the second input contact patch366and the second output contact patch372. For example, a sum of a length of a first input contact patch vector length extending from the second input contact patch366to the input disk axis of rotation310and aligned substantially perpendicular to the second input contact patch366, and a length of a first output contact patch vector length extending from the second output contact patch372to the output disk axis of rotation328and aligned substantially perpendicular to the second output contact patch372is greater than at least one of a length of a second input contact patch vector length extending from the second input contact patch366to the ring member axis of rotation355and aligned substantially perpendicular to the second input contact patch366, and a length of a second output contact patch vector length extending from the second output contact patch372to the ring member axis of rotation355and aligned substantially perpendicular to the second output contact patch372.

With reference toFIGS. 11 and 12, the speed ratio selector344may be used to selectively adjust the speed ratio of the continuously variable transmission300.FIG. 11illustrates the speed ratio selector344arranged in a first speed ratio position. In this position the ring member342engages the first and second output disks330and332near their respective outer edges334and338, and the ring member342engages the first and second input disks306and308closer toward the input disk axis of rotation310. This arrangement produces the lowest speed ratio (e.g., speed ratio=(rotational speed of output shaft44)÷(rotational speed of input shaft42)), wherein the output shaft44has a lower rotational speed than the input shaft42.

FIG. 12illustrate the speed ratio selector344arranged in a second speed ratio position. In this position the ring member342engages the first and second input disks306and308near their respective outer edges312and320, and the ring member346engages the first and second output disks330and332closer toward the output disk axis of rotation328. This arrangement produces the highest speed ratio, wherein the output shaft44has a higher rotational speed than the input shaft42. The speed ratio selector60may be infinitely adjustable between the first speed ratio position (for example, as illustrated inFIG. 11) and the second speed ratio position (for example, as illustrated inFIG. 12).

As described previously, input biasing mechanism329and output biasing mechanism341may include various configurations. An example of one such configuration is illustrated inFIGS. 13 and 14, which includes a hydraulic system used to produce the biasing force for controlling the traction forces generated between the ring member342and the first and second input disks306and308and the first and second output disks330and332. This particular configuration of the input and output biasing mechanisms329and341utilizes hydraulic pressure to generate a biasing force for urging the second input disk308toward the first output disk306and the second output disk332toward the first output disk330. Input biasing mechanism329may include a hydraulic reservoir384configured to exert a biasing force against the second input disk308. The hydraulic reservoir384may be defined by a rear surface385of the second input disk308and a cover386positioned adjacent the second input disk308. The second input disk308may slideably engage the input shaft42. The cover386may include a generally cylindrically-shaped flange387that slideably engages a generally cylindrically-shaped flange388extending from the rear surface385of the second input disk308. A seal389, such as an O-ring, may be disposed between the flange387of the cover386and the flange388of the second input disk308to prevent hydraulic fluid from escaping hydraulic reservoir384. A seal390may be employed to seal an opening that may occur between the cover386and the input shaft42and an opening that may occur between the second input disk308and the input shaft42.

The output biasing mechanisms341may be similarly configured as the input biasing mechanism329. For example, the output biasing mechanism341may include a hydraulic reservoir391configured to exert a biasing force against the second output disk332. The hydraulic reservoir391may be defined by a rear surface392of the second output disk330and a cover393positioned adjacent the second output disk330. The second input disk330may slideably engage the output shaft44. The cover393may include a generally cylindrically-shaped flange394that slideably engages a generally cylindrically-shaped flange395extending from the rear surface392of the second output disk330. Seal389, such as an O-ring, may be disposed between the flange394of the cover393and the flange395of the second output disk330to prevent hydraulic fluid from escaping hydraulic reservoir391. Seal390may be employed to seal an opening that may occur between the cover393and the output shaft44and an opening that may occur between the second output disk330and the output shaft44.

A fluid passage396may fluidly connect the hydraulic reservoir384of the input biasing mechanism329to the hydraulic reservoir391of the output biasing mechanism341. A hydraulic pump397may be fluidly connected to the fluid passage396. The hydraulic pump397operates to control a pressure of the hydraulic fluid present within the system, and thus the traction forces generated between the ring member342and the first and second input disks306and308and the first and second output disks330and332.

The input and output biasing mechanisms329and341operate in conjunction with one another to provide a generally consistent biasing force. The volume of the hydraulic reservoirs384and391may vary as the speed ratio of the continuously variable transmission300is varied. For example,FIG. 13illustrates the continuously variable transmission300arranged in the first speed ratio position, andFIG. 14illustrates the speed ratio selector344arranged in a second speed ratio position. With the speed ratio selector342arranged in the first speed ratio position (i.e.,FIG. 13), the ring member342engages the first and second output disks330and332near their respective outer edges334and338, and the ring member342engages the first and second input disks306and308closer toward the input disk axis of rotation310. This arrangement produces a maximum separation between the first input disk306and the second input disk308, and a minimum separation between the first output disk330and the second output disk332. With the speed ratio selector342arranged in the second speed ratio position (i.e.,FIG. 14), the ring member342engages the first and second input disks306and308near their respective outer edges312and320, and the ring member346engages the first and second output disks330and332closer toward the output disk axis of rotation328. This arrangement produces a minimum separation between the first input disk306and the second input disk308, and a maximum separation between the first output disk330and the second output disk332.

Selectively moving the ring member342from the first speed ratio position (i.e.,FIG. 13) toward the second speed ratio position (i.e.,FIG. 14) causes the second input disk308to move toward the first input disk306and thereby increase the volume of the hydraulic reservoir384, and the second output disk332to move away from the first output disk330, and thereby decrease the volume of the hydraulic reservoir391. On the other hand, moving the ring member342from the second speed ratio position (i.e.,FIG. 14) toward the first speed ratio position (i.e.,FIG. 13) causes the second input disk308to move away from the first input disk306and thereby increase the volume of the hydraulic reservoir384, and the second output disk332to move toward the first output disk330and thereby decrease the volume of the hydraulic reservoir391. Hydraulic fluid may be transferred back and forth between the hydraulic reservoir384and hydraulic reservoir391through fluid passage396as the ring member342is cycled between the various speed ratio positions.

With reference toFIG. 15, an alternately configured exemplary continuously variable transmission400is operable for transferring rotational energy between the input shaft42and the output shaft44. The input shaft42is rotatable about the input axis of rotation46and the output shaft44is rotatable about the output axis of rotation48. The input axis of rotation46may be arranged substantially parallel to the output axis of rotation48. The input axis of rotation46may be offset from the output axis of rotation48by the distance50. The input and output shafts42and44, respectively, may each be rotatably supported within the housing52by bearings54. The position and orientation of the input shaft42is generally fixed relative to the output shaft44.

The continuously variable transmission400may include an input drive mechanism402and an output drive mechanism404spaced from the input drive mechanism402. The input and output drive mechanisms402and404may be arranged in series. The input and output drive mechanisms402and404, respectively, operate in conjunction with one another to transfer rotational torque from the input shaft42to the output shaft44.

The input drive mechanism402may employ an input disk406rotatable about the input axis of rotation46. The input disk406may be fixedly attached or integrally formed with the input shaft42. The input disk406extends generally radially outward from the input axis of rotation46. An edge408defines an outer circumferential perimeter of the input disk406. The input disk406may include a generally convex conically-shaped input disk first traction surface410and an opposite input disk second traction surface412. The input disk first and second traction surfaces410and412may be generally configured as mirror opposites when viewed from the perspective ofFIG. 15.

The output drive mechanism404may be similarly configured as the input drive mechanism402, and may include for example, an output disk414rotatable about the output axis of rotation48. The output disk414may be fixedly attached or integrally formed with the output shaft48. The output disk414extends generally radially outward from the output axis of rotation48. An edge416defines an outer circumferential perimeter of the output disk414. The output disk414may include a generally convex conically-shaped output disk first traction surface418and an opposite output disk second traction surface420. The output disk first and second traction surfaces418and420may be generally configured as mirror opposites when viewed from the perspective ofFIG. 15.

The continuously variable transmission400may include a ring member422operably connecting the input drive mechanism402to the output drive mechanism404. The ring member422may be moved radially relative to the input drive mechanism402and the output drive mechanism404. The radial location of the ring member422may be selectively adjusted relative to the input and output drive mechanisms402and404to vary the speed ratio (e.g., speed ratio=(rotational speed of output shaft44)÷(rotational speed of input shaft42)) of the continuously variable transmission400.

The ring member422may include a pair of interconnected co-rotating rings. The co-rotating rings may include an input traction ring426that engages the input disk first traction surface410, and an output traction ring428that engages the output disk first traction surface418. A generally cylindrical-shaped connecting ring430may fixedly connect the input traction ring426to the output traction ring428. The input and output traction rings426and428may be arranged substantially parallel to one another and substantially perpendicular to the input and output axis of rotation46and48.

The input traction ring426may include an input ring traction surface432engageable with the input disk first traction surface410. The input ring traction surface432may be configured as a continuous ring. The input ring traction surface432may be located at a radius434from a ring member axis of rotation436.

The output traction ring428may include an output ring traction surface438engageable with the output disk first traction surface418. The output ring traction surface438may be configured as a continuous ring. The output ring traction surface428may be located at a radius440from the ring member axis of rotation436. The output ring traction surface438and the input ring traction surface432may be arranged at opposite axial ends of the ring member422, with the input ring traction surface432generally facing the output ring traction surface438.

With reference toFIGS. 15 and 16, the continuously variable transmission400may include an intermediate traction ring442disposed between the input traction ring426and the output traction ring428. The intermediate traction ring442may be generally configured as an annular disk having an outer circumference444and an inner circumference446. The intermediate traction ring442may be aligned generally parallel to the input and output traction rings426and428and substantially perpendicular to the ring member axis of rotation436. The outer circumference446may include a helical spline448, or similar connecting mechanism, that slideably engages a corresponding connecting mechanism, for example a helical spline450, located on an inner circumference452of the connecting ring430. The helical splines448and450enable the intermediate traction ring442to move axially along an axial path of travel (i.e., along ring member axis of rotation436) relative to the ring member422while maintaining the angular orientation of the intermediate traction ring relative to the input and output traction rings426and428and the ring member axis or rotation436. The helical splines448and450operate to rotatably fix the intermediate traction ring442to the ring member422, thereby causing the intermediate traction ring to rotate in substantial unison with the input and output traction rings426and428.

With reference toFIGS. 15 and 17, moving ring member422radially along radial path of travel455causes a corresponding axial movement of ring member422and intermediate traction ring442in opposite directions along axial path of travel451. For example, moving ring member422radially upward as viewed from the perspective ofFIGS. 15 and 17) from the radial position illustrated inFIG. 17to the radial position illustrated inFIG. 15causes input traction ring426to move rightward (as viewed from the perspective ofFIGS. 15 and 17) as input ring traction surface432travels radially outward along input disk first traction surface410and output ring traction surface438travels radially inward along output disk first traction surface418. This also causes intermediate traction ring442to move leftward (as viewed from the perspective ofFIGS. 15 and 17) as intermediate input traction surface454travels radially outward along input disk second traction surface412and intermediate output traction surface456travels radially inward along output disk second traction surface420. Moving ring member422radially downward (as viewed from the perspective ofFIGS. 15 and 17) causes input traction ring426, output traction ring438and the intermediate traction ring442to move axially along axial path of travel451in a direction opposite the direction when moving the ring member422radially upward.

The intermediate traction ring442may include an intermediate input traction surface454engageable with the input disk second traction surface412. The intermediate input traction surface454may be configured as a continuous ring. The intermediate input traction surface454may be located at a radius458from the ring member axis of rotation436.

The intermediate traction ring442may include an intermediate output traction surface456engageable with the output disk second traction surface420. The intermediate output traction surface456may be configured as a continuous ring. The intermediate output traction surface456may be located at the radius458from the ring member axis of rotation436. The intermediate output traction surface458and the intermediate input traction surface454may be arranged on opposite sides of the intermediate traction ring442, with the intermediate input traction surface454generally facing in an opposing direction of the intermediate output traction surface456.

The ring member422may be moved radially along a radial path of travel455relative to the input drive mechanism402and the output drive mechanism404. The radial location of the ring member422may be selectively adjusted relative to the input and output drive mechanisms402and404to vary the speed ratio (e.g., speed ratio=(rotational speed of output shaft44)÷(rotational speed of input shaft42)) of the continuously variable transmission400.

A speed ratio selector460may be operably connected to the ring member422to selectively adjust the speed ratio of the continuously variable transmission400. The speed ratio selector460operates to adjust the radial location of the ring member422relative to the input and output drive mechanisms402and404to achieve a selected speed ratio. The speed ratio selector460may have any of a wide variety of configurations. The speed ratio selector460may employ any device capable of adjusting a location of the ring member460relative to the input disk406of the input drive mechanism402, and the output disk414of the output drive mechanism404.

The continuously variable transmission400operates to transfer torque from the input shaft42to the output shaft44. Torque from the input shaft42may be transferred from the input disk406to the ring member422across a first input contact patch462where the input ring traction surface432engages the input disk first traction surface410.

Torque may be transferred from the ring member422to the output disk414across a first output contact patch468where the output ring traction surface438engages the output disk first traction surface418. Torque transferred from the ring member422to output disk414may be output through the output shaft44.

Torque from the input shaft42may also be transferred from the input disk406through the intermediate traction ring442to the output disk414. Torque from the input disk406may be transmitted across a second input contact patch474where the intermediate input traction surface454of the intermediate traction ring442engages the input disk second traction surface412. Torque may be transferred from the intermediate traction ring442to the output disk414across a second output contact patch476where the intermediate output traction surface456of the intermediate traction ring442engages the output disk second traction surface420. The first and second input contact patches462and474are located at a radius478from the input axis of rotation46. The first and second output contact patches468and476are located at a radius480from the output axis of rotation48. The radius478of the first and second input contact patches462and474, and the radius480of the first and second output contact patches468and476varies as the speed ratio of the continuously variable transmission400is varied.

The input and output shafts42and44exert their respective torques on the input disk first and second traction surfaces410and412and the output disk first and second traction surfaces418and420, respectively. The torques generate equal and opposite forces at the first input and output contact patches462and468and the second input and output contact patches474and476. The forces may be transmitted from the input disk406to the output disk414by traction contact between the input and output disks406and414and the ring member422.

The traction forces generated at the input first input contact patch462and the first output contact patch468includes a radial component that urges the ring member422tightly into contact with the input and output disks406and414to help maintain a position of the ring member422relative to the input and output disks406and414. A tangential component transmits a tractive force between the ring member422and the input and output disks406and414. A normal component is dependent on the geometry of the input and output disks406and414and a circumferential location of the contact patches462and468relative to one another, and is generally adequate to prevent slippage between the input and output disks406and414and the ring member422. The input disk second traction surface412and output disk second traction surface420experiences a set of forces that balance the forces on the opposite input disk first traction surface410and the output disk first traction surface418.

The vector component forces (i.e., radial, tangential and normal) acting at the first and second input contact patches462and474and the first and second output contact patches468and476generally balance to produce a net zero force. The opposing forces tend to cause the ring member422and intermediate traction ring442to pinch the input and output disks406and414to produce sufficient clamping force between the ring member422and intermediate traction ring442and the input and output disks406and414to accomplish traction without slip.

The speed ratio of the continuously variable transmission400is a function of the radial location478of the first and second input contact patches462and474, and the radial location480of the first and second output contact patches468and476. The speed ratio of the continuously variable transmission400is partially determined by the radial location at which the input ring traction surface432engages the input disk first traction surface410and the radial location at which the intermediate input traction surface454engages the input disk second traction surface412(i.e., the radial location478of the first and second input contact patches462and474). The rotational speed of the output shaft44increases, relative to the rotational speed of the input shaft42, as the radial location478of the first and second input contact patches462and474increases. On the other hand, the rotational speed of the output shaft44decreases as the radial location478of the first and second input contact patches462and474decreases.

The radial location at which the output ring traction surface438engages the output disk first traction surface418and the radial location at which the intermediate output traction surface456engages the output disk second traction surface420(i.e., the radial location480of the first and second output contact patches468and476) has a compounding influence on speed ratio. The rotational speed of the output shaft44increases, relative to the rotational speed of the input shaft42, as the radial location480of the first and second output contact patches468and476decreases. On the other hand, the rotational speed of the output shaft44decreases as the radial location480of the first and second output contact patches468and476increases.

The speed ratio may be selectively adjusted by moving the location of the ring member axis of rotation436relative to the input axis of rotation46and/or the output axis of rotation48, which effects the radial location478at which the ring member422engages the input disk406, and the radial location480at which the ring member422engages the output disk414. Moving the ring member422radially relative to the input disk406results in corresponding movement of the ring member422relative to the output disk414. For example, moving the ring member422radially outward relative to the input disk406also moves the ring member422radially inward relative to the output disk414. On the other hand, moving the ring member422radially inward relative to the input disk406also moves the ring member422radially outward relative to the output disk414.

With continued reference toFIG. 15, the first input contact patch462is aligned substantially perpendicular to a first input contact patch vector482extending from the first input contact patch462to the input axis of rotation46, and aligned substantially perpendicular to a second input contact patch vector484extending from the first input contact patch462to the ring member axis of rotation436. Similarly, the first output contact patch468is aligned substantially perpendicular to a first output contact patch vector486extending from the first output contact patch468to the output axis of rotation48, and aligned substantially perpendicular to a second output contact patch vector488extending from the first output contact patch468to the ring member axis of rotation436. The configuration and arrangement of the various components of the continuously variable transmission400is such that a sum of a length of the first input contact patch vector482and a length of the first output contact patch vector486is greater than a length of the second input contact patch vector484and a length of the second output contact patch vector488. The following relationship holds true for all speed ratios:
((length of first input contact patch vector 482)+(length of first output contact patch vector 486))>(length of second input contact patch vector 484); and  A.
((length of first input contact patch vector 482)+(length of first output contact patch vector 486))>(length of second output contact patch vector 488)  B.

A similar relationship also holds true for the second input contact patch474and the second output contact patch476. For example, a sum of a length of a first input contact patch vector length extending from the second input contact patch474to the input axis of rotation46and aligned substantially perpendicular to the second input contact patch474, and a length of a first output contact patch vector length extending from the second output contact patch476to the output axis of rotation48and aligned substantially perpendicular to the second output contact patch476is greater than at least one of a length of a second input contact patch vector length extending from the second input contact patch474to the ring member axis of rotation436and aligned substantially perpendicular to the second input contact patch474, and a length of a second output contact patch vector length extending from the second output contact patch476to the ring member axis of rotation436and aligned substantially perpendicular to the second output contact patch476.

With reference toFIGS. 15 and 17, the speed ratio selector460may be used to selectively adjust the speed ratio of the continuously variable transmission400.FIG. 15illustrates the speed ratio selector460arranged in a first speed ratio position. In this position the ring member422engages the input disk406near its respective outer edge408, and the ring member422engages the output disk414closer toward the output axis of rotation48. This arrangement produces the highest speed ratio (e.g., speed ratio=(rotational speed of output shaft44)÷(rotational speed of input shaft42)), wherein the output shaft44has a higher rotational speed than the input shaft42.

FIG. 17illustrate the speed ratio selector460arranged in a second speed ratio position. In this position the ring member422engages the output disk414near its outer edge416, and the ring member422engages the input disk406closer toward the input axis of rotation46. This arrangement produces the lowest speed ratio, wherein the output shaft44has a lower rotational speed than the input shaft42. The speed ratio selector460may be infinitely adjustable between the first speed ratio position (for example, as illustrated inFIG. 15) and the second speed ratio position (for example, as illustrated inFIG. 17).

With reference toFIG. 18, an alternately configured exemplary continuously variable transmission700is operable for transferring rotational energy between input shaft42and the output shaft44. Continuously variable transmission700is similarly configured as continuously variable transmission400, but utilizes an alternate mechanism for controlling alignment of an intermediate traction ring702and a ring member706relative to input disk406and output disk414. Intermediate traction ring702and ring member706operably connect input drive mechanism402to output drive mechanism404. Ring member706and intermediate traction ring702may be selectively moved in unison radially relative to the input drive mechanism402and the output drive mechanism404. The radial location of the ring member706and the intermediate traction ring702may be selectively adjusted relative to the input and output drive mechanisms402and404to vary the speed ratio (e.g., speed ratio=(rotational speed of output shaft44)÷(rotational speed of input shaft42)) of the continuously variable transmission700.

The ring member706may include a pair of interconnected co-rotating rings. The co-rotating rings may include an input traction ring708that engages the input disk first traction surface410, and an output traction ring710that engages the output disk first traction surface418. The input and output traction rings708and710may be arranged substantially parallel to one another and substantially perpendicular to the input and output axis of rotation46and48.

Input traction ring708may include a generally cylindrical-shaped input traction ring support712extending laterally outward from input traction ring708. Output traction ring710may include an output traction ring support714extending laterally outward from output traction ring710. Output traction ring support714may be sized larger (i.e., have a larger diameter) than input traction ring support712. Output traction ring support714extends around and at least partially overlays input traction ring support712. An inner circumference716of output traction ring support714may have a larger diameter than a diameter of an outer circumference718of input traction ring support712, thereby forming a circumferential annulus720between input traction ring support712and output traction ring support714. Input and output traction ring supports712and714may be fixedly connected to one another by a radial connector722to cause input traction ring708and output traction ring710to rotate in unison.

The input traction ring708may include an input ring traction surface724engageable with the input disk first traction surface410. The input ring traction surface724may be configured as a continuous ring.

The output traction ring710may include an output ring traction surface726engageable with the output disk first traction surface418. The output ring traction surface726may be configured as a continuous ring. The output ring traction surface726and the input ring traction surface724may be arranged so as to generally face one another.

With reference toFIGS. 15 and 16, the continuously variable transmission700may include the intermediate traction ring702disposed between the input traction ring708and the output traction ring710. The intermediate traction ring702may be generally configured as an annular disk having an outer circumference728and an inner circumference730. The intermediate traction ring702may be aligned generally parallel to the input and output traction rings708and710and substantially perpendicular to the ring member axis of rotation732. The outer circumference728may include a generally cylindrical-shaped input traction ring support734extending laterally outward from intermediate traction ring702. Intermediate traction ring support734at least partially extends into the annulus720formed between output traction ring support714and input traction ring support712. An outer circumference736of intermediate traction ring support734may slideably engage the inner circumference716of output traction ring support714. This arrangement enables the intermediate traction ring702to move axially (i.e., along ring member axis of rotation732) relative to the ring member706while maintaining the angular orientation of the intermediate traction ring734relative to the input and output traction rings708and710and the ring member axis or rotation732. Alternatively, an inner circumference738of intermediate traction ring support734may slideably engage the outer circumference718of input traction ring support712.

The intermediate traction ring702may include an intermediate input traction surface740engageable with the input disk second traction surface412. The intermediate input traction surface740may be configured as a continuous ring.

The intermediate traction ring702may include an intermediate output traction surface742engageable with the output disk second traction surface420. The intermediate output traction surface742may be configured as a continuous ring. The intermediate output traction surface742and the intermediate input traction surface740may be arranged on opposite sides of the intermediate traction ring702, with the intermediate input traction surface740generally facing in an opposing direction of the intermediate output traction surface742.

With continued reference toFIGS. 18 and 19, moving ring member706radially along radial path of travel455causes a corresponding axial movement of ring member422and intermediate traction ring442in opposite directions along axial path of travel451. For example, moving ring member422radially upward (as viewed from the perspective ofFIGS. 18 and 19) from the radial position illustrated inFIG. 19to the radial position illustrated inFIG. 18causes input traction ring708to move rightward (as viewed from the perspective ofFIGS. 18 and 19) as input ring traction surface724travels radially outward along input disk first traction surface410and output ring traction surface726travels radially inward along output disk first traction surface418. This also causes intermediate traction ring702to move leftward (as viewed from the perspective ofFIGS. 18 and 19) as intermediate input traction surface740travels radially outward along input disk second traction surface412and intermediate output traction surface742travels radially inward along output disk second traction surface420. Moving ring member706radially downward (as viewed from the perspective ofFIGS. 18 and 19) causes input traction ring708, output traction ring710and the intermediate traction ring702to move axially along axial path of travel451in a direction opposite the direction when moving the ring member706radially upward.

The ring member706may be moved radially along path of travel455relative to the input drive mechanism402and the output drive mechanism404. The radial location of the ring member706may be selectively adjusted relative to the input and output drive mechanisms402and404to vary the speed ratio (e.g., speed ratio=(rotational speed of output shaft44)÷(rotational speed of input shaft42)) of the continuously variable transmission700.

The speed ratio selector460may be operably connected to the ring member706to selectively adjust the speed ratio of the continuously variable transmission700. The speed ratio selector460operates to adjust the radial location of the ring member706relative to the input and output drive mechanisms402and404to achieve a selected speed ratio. The speed ratio may be selectively adjusted by moving the location of the ring member axis of rotation473relative to the input axis of rotation46and/or the output axis of rotation48, which effects the radial locations at which the ring member706engages the input disk406and the output disk414. Moving the ring member706radially relative to the input disk406results in corresponding movement of the ring member706relative to the output disk414. For example, moving the ring member706radially outward relative to the input disk406also moves the ring member706radially inward relative to the output disk414. On the other hand, moving the ring member706radially inward relative to the input disk406also moves the ring member706radially outward relative to the output disk414

A common feature between the various exemplary configurations of the continuously variable transmission, among others, is that the sum of the input and output contact patch vector lengths (for example, a length of first input contact patch vector154and first output contact patch vector158, as illustrated inFIG. 2) is greater than the lengths of corresponding ring member vectors156and160(for example, input ring member102as illustrated inFIG. 2). Also, each of the exemplary configurations depict the ring members as having their respective traction surfaces (for example, input ring first traction surface112, as illustrated inFIG. 1) positioned at a fixed radius, whereas the radius of the corresponding disk traction surface (for example, first input disk traction surface68, as illustrated inFIG. 1) varies, as this arrangement may generally provide the greatest range of drive ratios. Alternatively, the radial location of the disk traction surface may be fixed and the radial location of the ring traction surface may be allowed to vary as the means for adjusting the drive ratio.

With reference toFIGS. 20 and 21, an exemplary two-stage continuously variable transmission500is operable for transferring rotational energy between the input shaft42and the output shaft44. The two-stage continuously variable transmission500may include a first drive mechanism502and a second drive mechanism504. The first and second drive mechanisms502and504may be arranged in series. The first and second drive mechanisms502and504operate to transfer rotational torque from the input shaft42to the output shaft44. The first and second drive mechanisms502and504may be selectively adjusted to vary a speed ratio (e.g., speed ratio=(rotational speed of output shaft44)÷(rotational speed of input shaft42)) of the tow-stage continuously variable transmission500. The two-stage continuously variable transmission500may employ a speed ratio selector506operable to selectively adjust the speed ratio.

The first drive mechanism502may be fixedly attached to the input shaft42and the second drive mechanism504may be fixedly attached to the output shaft44. An intermediate shaft508operably connects the first drive mechanism502to the second drive mechanism504. The input shaft42and the output shaft44are rotatable about a common axis of rotation510. The position and orientation of the input shaft42is generally fixed relative to the output shaft44.

The first drive mechanism502may employ a first input disk512and a first output disk514positioned adjacent the first input disk512. The first input and output disks512and514are each rotatable about the axis of rotation510. The first input and output disks512and514extend generally radially outward from the axis of rotation510. An edge516defines an outer circumferential perimeter of the first input disk512. The first input disk512may include a first input disk traction surface520positioned adjacent input shaft42and an opposite inner surface522positioned adjacent the first output disk514. The inner surface522of the first input disk62may have generally planar surface contour, as illustrated, for example, inFIG. 20, or may include various other shapes and/or contours.

With continued reference toFIG. 20, an edge524defines an outer circumferential perimeter of the first output disk514. The first output disk514may include an inner surface526positioned adjacent the first input disk512and a first output disk traction surface528located opposite the inner surface526. The first output disk514may be generally configured as a mirror image of the first input disk512when viewed from the perspective ofFIG. 20. Similar to first input disk512, the inner surface526of the first output disk514may have generally planar surface contour, as illustrated, for example, inFIG. 20, or may include various other shapes and/or contours. The first output disk514may be fixedly attached to the intermediate shaft508.

The first input disk512and the first output disk514may be rotatably supported relative to one another. For example, a bearing530may be disposed between the inner surface522of the first input disk512and the inner surface526of the first output disk514. The bearing530may be integrally formed with the first input disk512and the first output disk514, for example, as illustrated inFIG. 20, or may be configured as a separate component that attaches to the inner surface522of the first input disk512and the inner surface526of the first output disk514.

The second drive mechanism504may be similarly configured as the first drive mechanism502, and may include for example, a second input disk532and a second output disk534positioned adjacent the second input disk532. The second input disk532and the second output disk534are each rotatable about the axis of rotation510. The second input and output disks532and534extend generally radially outward from the axis of rotation510.

An edge536defines an outer circumferential perimeter of the second input disk532. The second output disk534may include a second input disk traction surface538and an opposite inner surface540positioned adjacent the second output disk534. The inner surface540of the second input disk532may have generally planar surface contour, as illustrated, for example, inFIG. 20, or may include various other shapes and/or contours. The second input disk532may be fixedly attached to the intermediate shaft508.

The second output disk534may be fixedly attached to the output shaft44. An edge542defines an outer circumferential perimeter of the second output disk534. The second output disk534may include an inner surface544positioned adjacent the second input disk532and a second output disk traction surface546located opposite the inner surface544. The second output disk534may be generally configured as a mirror image of the second input disk532when viewed from the perspective ofFIG. 20. Similar to second input disk532, the inner surface544of the second output disk534may have a generally planar surface contour, as illustrated, for example, inFIG. 20, or may include various other shapes and/or contours.

The second input disk532and the second output disk534may be rotatably supported relative to one another. For example, the bearing530may be disposed between the inner surface540of the second input disk532and the inner surface544of the second output disk534. The bearing530may be integrally formed with the second input disk532and the second output disk534, for example, as illustrated inFIG. 20, or may be configured as a separate component that attaches to the inner surface540of the second input disk532and the inner surface544of the second output disk534.

The first drive mechanism502may include a first ring member548that operates to rotatably couple the first input disk512to the first output disk514. The first ring member548is rotatable about a first ring member axis of rotation549. The first ring member axis of rotation549is oriented substantially perpendicular to a plane extending through a bearing588for rotatably supporting the first ring member548. The first ring member548may be moved radially relative to the first input disk512and the first output disk514. The radial location of the first ring member548may be selectively adjusted relative to the first input disk512and the first output disk514to vary the speed ratio of the first drive mechanism502(e.g., first drive mechanism speed ratio=(rotational speed of output shaft44)÷(rotational speed of the intermediate shaft508)).

The second drive mechanism504may include a second ring member550that operates to rotatably couple the second input disk532to the second output disk534. The second ring member550is rotatable about a second ring member axis of rotation551. The second ring member axis of rotation551is aligned substantially perpendicular to a plane extending through bearing588that rotatably supports the second ring member550. The second ring member550may be moved radially relative to the second input disk532and the second first output disk534. The radial location of the second ring member550may be selectively adjusted relative to the second input disk532and the second output disk534to vary the speed ratio of the second drive mechanism504(e.g., second drive mechanism speed ratio=(rotational speed of intermediate shaft508)÷(rotational speed of the output shaft44)).

The first ring member548may include a pair of interconnected co-rotating rings. The co-rotating rings may include an input traction ring552that engages the first input disk512, and an output traction ring554spaced from the input traction ring552and which engages the first output disk514. A generally cylindrical-shaped connecting ring556may fixedly connect the input traction ring552to the output traction ring554. The input and output traction rings552and554extend generally radially inward from the connecting ring556.

The input traction ring552may include a first ring member input traction surface558engageable with the first input disk traction surface520of the first input disk512. The output traction ring554may include a first ring member output traction surface560engageable with the first output disk traction surface528of the first output disk514. The first ring member input and output traction surfaces558and560may be configured as continuous rings. The first ring member input traction surface558may be located at a radius562from a ring member effective axis of rotation566. The ring member effective axis of rotation566may not coincide with the first ring member axis of rotation549or the second ring member axis of rotation551depending on the orientation of bearing588. Rather, the first and second ring member axis of rotation549and551may be oriented at an oblique angle relative to the ring member effective axis of rotation566. The ring member effective axis or rotation566is aligned substantially parallel to the axis of rotation510of input shaft42and output shaft44. The first ring member output traction surface560may be located at a radius564from the ring member effective axis of rotation566. The first ring member input and output traction surfaces558and560are arranged on opposite sides of the first ring member548, with the first ring member input traction surface558facing the first input disk512and the first ring member output traction surface560facing the first output disk514.

The second ring member550may be similarly configured as the first ring member548. The second ring member550may include a pair of interconnected co-rotating rings. The co-rotating rings may include an input traction ring568that engages the second input disk532, and an output traction ring570spaced from the input traction ring568and which engages the second output disk534. A generally cylindrical-shaped connecting ring572may fixedly connect the input traction ring568to the output traction ring570. The input and output traction rings568and570extend generally radially inward from the connecting ring572.

The input traction ring568may include a second ring member input traction surface574engageable with the second input disk traction surface538of the second input disk532. The output traction ring570may include a second ring member output traction surface576engageable with the second output disk traction surface546of the second output disk534. The second ring member input and output traction surfaces574and576may be configured as continuous rings. The second ring member input traction surface574may be located at a radius578from a ring member effective axis of rotation566. The second ring member output traction surface576may be located at a radius580from the ring member effective axis of rotation566. The first ring member input and output traction surfaces574and576are arranged on opposite sides of the second ring member550, with the second ring member input traction surface574facing the second input disk532and the second ring member output traction surface576facing the second output disk534.

The speed ratio selector506may be operably connected to the first and second ring members548and550to selectively adjust the speed ratio of the two-stage continuously variable transmission500. The speed ratio selector506operates to adjust the radial location of the first ring member548relative to the first input disk512and the first output disk514, and adjust the radial location of the second ring member550relative to the second input disk532and the second output disk534, to achieve a selected speed ratio.

The speed ratio selector506may have any of a wide variety of configurations. The speed ratio selector506may employ any device capable of adjusting a location of the first ring member548relative to the first input and output disks512and514, and the location of the second ring member550relative to the second input and output disk532and534. An example of one such configuration is illustrated inFIGS. 20-22.

With reference toFIGS. 20 and 21, the speed ratio selector506may include an actuator582having a hollow inner region584defined by a generally circular cylindrically-shaped inner surface586. A longitudinal axis of the inner surface586substantially coincides with the ring member effective axis of rotation566. The first and second ring members548and550may be rotatably disposed within the interior region584of the actuator582. The first ring member548may be rotatably supported on a bearing588mounted on the inner surface586of the actuator582. The second ring member550may be similarly rotatably mounted to the inner surface586of the actuator582using a second bearing588. The bearing588may be configured as a separate component or may be at least partially integrally formed with the actuator582and/or first and second ring members548and550.

The actuator582may be rotatably attached to the housing55, for example, using one or more bearings590. The bearing590may be mounted to an outer circumference592of the actuator582and the housing55. The outer circumference592of the actuator582may have a generally circular shape with a center axis that coincides with an axis of rotation594of the actuator582. The axis of rotation594of the actuator582may be offset from the ring member effective axis of rotation566by a distance596. As a consequence, a thickness T of the actuator582varies circumferentially, as shown, for example, inFIG. 19, with a minimum and maximum thickness T of the actuator occurring on diametrically opposite sides of the actuator582. The eccentricity between the inner surface586and the outer circumference592of the actuator582allows a radial location of the first and second ring members548and550to be selectively varied relative to the first input and output disks512and514and the second input and output disks532and534by rotating the actuator582about its axis of rotation594.

The two-stage continuously variable transmission500operates to transfer torque from the input shaft42to the output shaft44. Torque from the input shaft42may be transferred from the first input disk512to the first ring member548across a first input contact patch598where the first ring member input traction surface558engages the first input disk traction surface520. Torque may be transferred from the first ring member548to the first output disk514across a first output contact patch600where the first ring member output traction surface560engages the first output disk traction surface528. The first input contact patch598is located at a radius602from the input and output shaft axis of rotation510, and the first output contact patch600is located at a radius604from the input and output shaft axis of rotation510. The radius602of the first input contact patch598and the radius604of the first output contact patch600varies as the speed ratio of the two-stage continuously variable transmission500is varied.

Torque from the first output disk514is transmitted along the intermediate shaft508to the second input disk532. Torque from the second input disk532may be transferred to the second ring member550across a second input contact patch606where the second ring member input traction surface574engages the second input disk traction surface538. Torque may be transferred from the second ring member550to the second output disk534across a second output contact patch608where the second ring member output traction surface576engages the second output disk traction surface546. The second input contact patch606is located at a radius610from the input and output shaft axis of rotation510, and the second output contact patch608is located at a radius612from the input and output shaft axis of rotation510. The radius610of the second input contact patch606and the radius612of the second output contact patch608varies as the speed ratio of the two-stage continuously variable transmission500is varied. Torque transferred from the second ring member550to second output disk534may be output through the output shaft44.

The speed ratio of the two-stage continuously variable transmission500is a function of the radial locations602and604of the first input and output contact patches598and600, respectively, and the radial locations610and612of the second input and output contact patches606and608, respectively. The rotational speed of the output shaft44increases, relative to the rotational speed of the input shaft42, as the radial locations602and610of the first and second input contact patches598and606respectively increase, and the radial locations604and612of the first and second output contact patches608and612respectively decrease. On the other hand, the rotational speed of the output shaft44decreases as the radial locations602and610of the first and second input contact patches598and606respectively decrease, and the radial locations604and612of the first and second output contact patches608and612respectfully increase.

With reference toFIGS. 20 and 22, the speed ratio selector506may be used to selectively adjust the speed ratio of the two-stage continuously variable transmission500.FIG. 20illustrates the speed ratio selector506arranged in a first speed ratio position. In this position the first and second ring members548and550engage the first and second output disks514and534near their respective outer edges524and542, and engage the first and second input disks512and532closer toward the input and output axis of rotation510. This arrangement produces the lowest speed ratio (e.g., speed ratio=(rotational speed of output shaft44)÷(rotational speed of input shaft42)), wherein the output shaft44has a lower rotational speed than the input shaft42.

FIG. 22illustrates the speed ratio selector506arranged in a second speed ratio position. In this position the first and second ring members548and550engage the first and second output disks514and534near their respective outer edges524and542, and engage the first and second input disks512and532closer toward the input and output axis of rotation510. This arrangement produces the lowest speed ratio (e.g., speed ratio=(rotational speed of output shaft44)÷(rotational speed of input shaft42)), wherein the output shaft44has a lower rotational speed than the input shaft42. The speed ratio selector506may be infinitely adjustable between the first speed ratio position (for example, as illustrated inFIGS. 20 and 21) and the second speed ratio position (for example, as illustrated inFIG. 22). The illustrated speed ratio selector506is configured to provide a shift ratio of 1:1, but may also be configured to provide other speed ratios depending on the design and performance requirement of a particular application.

The configuration of the first drive mechanism502of the continuously variable drive mechanism500is such that a sum of the radial location602of the first input contact patch598and the radial location604of the first output contact patch600is greater than the radius562of the first ring member input traction surface558and the radius564of the first ring member output traction surface560. The following holds true for all speed ratios:
((radius 602)+(radius 604))>(radius 562)  A.
((radius 602)+(radius 604))>(radius 564)  B.

A similar relationship also holds true for the second drive mechanism504. For example, the configuration of the second drive mechanism504of the continuously variable transmission500is such that a sum of the radial location610of the second input contact patch606and the radial location612of the second output contact patch608is greater than the radius578of the second ring member input traction surface574and the radius580of the second ring member output traction surface576. The following holds true for all speed ratios:
((radius 610)+(radius 612))>(radius 578)  A.
((radius 610)+(radius 612))>(radius 580)  B.

It is intended that the scope of the present methods and apparatuses be defined by the following claims. However, it must be understood that the various disclosed configurations and operation of the continuously variable transmission may be practiced otherwise than is specifically explained and illustrated without departing from its spirit or scope. It should be understood by those skilled in the art that various alternatives to the configurations described herein may be employed in practicing the claims without departing from the spirit and scope as defined in the following claims. The scope of the disclosed systems and methods should be determined, not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. It is anticipated and intended that future developments will occur in the arts discussed herein, and that the disclosed systems and methods will be incorporated into such future examples. Furthermore, all terms used in the claims are intended to be given their broadest reasonable constructions and their ordinary meanings as understood by those skilled in the art unless an explicit indication to the contrary is made herein. In particular, use of the singular articles such as “a,” “the,” “said,” etc., should be read to recite one or more of the indicated elements unless a claim recites an explicit limitation to the contrary. It is intended that the following claims define the scope of the device and that the method and apparatus within the scope of these claims and their equivalents be covered thereby. In sum, it should be understood that the device is capable of modification and variation and is limited only by the following claims.