Continuously variable transmission

Embodiments of the inventions disclosed include a continuously variable transmission (CVT) where power is transmitted from a group of balls to a shaft via an idler. In one application, the CVT couples to a gearbox and to a generator of a wind turbine. Traction elements of a CVT can be coated and/or textured, using various coating materials and textures, via disclosed coating and/or texturing methods. Methods and systems for shifting a CVT are disclosed. Certain components for a CVT are disclosed. For example, in one embodiment, a CVT includes a shaft having a spline and a shift flange. In another embodiment, a CVT includes a stator adapted to cooperate with shifter components. Disclosed is a CVT configured to produce a variable output speed that is always greater than an input speed. In one embodiment, a CVT produces a variable output speed that is always lower than an input speed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The field of the invention relates generally to transmissions, and more particularly the invention relates to continuously variable transmissions.

2. Description of the Related Art

In order to provide a continuously variable transmission, various traction roller transmissions that transmit power through traction rollers supported in a housing between torque input and output discs have been developed. In such transmissions, the traction rollers are mounted on support structures which, when pivoted, cause the engagement of traction rollers with the torque discs in circles of varying diameters depending on the desired transmission ratio.

The use of a driving hub for a vehicle with a variable adjustable transmission ratio is known. In some instances a transmission uses iris plates to tilt the axis of rotation of the rollers. Other transmissions include a shaft about which an input disc and an output disc rotate. The input and output discs mount on the shaft and contact balls disposed equidistantly and radially about the shaft. The balls are in frictional contact with both discs and transmit power from the input disc to the output disc. An idler located concentrically over the shaft and between the balls aids in maintaining frictional contact between the balls and the input and output discs.

Wind turbines usually have drive trains that include gearboxes for managing power transfer from a rotor to a generator. Continuously variable transmissions such as those described below offer advantages to improve the performance and efficiency of wind turbines, typically resulting in lower cost of energy production.

SUMMARY OF THE INVENTION

The systems and methods illustrated and described herein have several features, no single one of which is solely responsible for its desirable attributes. Without limiting the scope as expressed by the description that follows, its more prominent features will now be discussed briefly. After considering this discussion, and particularly after reading the section entitled “Detailed Description of the Preferred Embodiment” one will understand how the features of the system and methods provide several advantages over traditional systems and methods.

In one aspect of the invention, a variable speed transmission comprises a longitudinal axis, balls distributed radially about the longitudinal axis, each ball having a tiltable axis about which it rotates, a rotatable input disc in contact with each of the balls, an output disc in contact with each of the balls, a rotatable idler in contact with each of the balls, a cage adapted to maintain the radial position and axial alignment of the balls and that is rotatable about the longitudinal axis, and an idler shaft operationally coupled to the idler and adapted to receive a torque output from the idler and transmit the torque output out of the transmission.

Some embodiments comprise a cage adapted to align the tiltable axes of the balls and further adapted to maintain the angular and radial positions of the balls. In some embodiments, the transmission disclosed here couples to a planetary gearset. For example, in one embodiment an input torque is supplied to a planetary gearset, wherein the planet carrier couples to the input disc, the sun gear couples to the cage, the ring gear is fixed and does not rotate, and an output torque is supplied from the transmission by the output disc.

In another aspect an axial force generator is disclosed for use with transmission embodiments described herein that is adapted to generate an axial force that increases the traction between the input disc, the balls, the idler and the output disc. In some embodiments, an amount of axial force generated by the axial force generator is a function of the transmission ratio of the transmission.

In other embodiments, each of the input disc, the balls, the output disc, and the idler have contact surfaces that are coated with a friction increasing coating material. The coating material of certain embodiments is a ceramic or a cermet. In yet other embodiments, the coating is a material selected from the group consisting of silicon nitride, silicon carbide, electroless nickel, electroplated nickel, or any combination thereof.

In still another aspect, a variable speed transmission is described comprising; first and second pluralities of balls distributed radially about the longitudinal axis, first and second rotatable input discs, an input shaft coaxial with the longitudinal axis and connected to the first and second input discs, a rotatable output disc positioned between the first and second pluralities of balls and in contact with each of the first and second pluralities of balls, a first generally cylindrical idler positioned radially inward of and in contact with each of the first plurality of balls, and a second generally cylindrical idler positioned radially inward of and in contact with each of the second plurality of balls.

For use with many embodiments described herein there is also disclosed an axial force generator adapted to apply an axial force to increase contact force between the input disc, the output disc and the plurality of speed adjusters, the axial force generator further comprising, a bearing disc coaxial with and rotatable about the longitudinal axis having an outer diameter and an inner diameter and having a threaded bore formed in its inner diameter, a plurality of perimeter ramps attached to a first side of the bearing disc near its outer diameter, a plurality of bearings adapted to engage the plurality of bearing disc ramps, a plurality of input disc perimeter ramps mounted on the input disc on a side opposite of the speed adjusters adapted to engage the bearings, a generally cylindrical screw coaxial with and rotatable about the longitudinal axis and having male threads formed along its outer surface, which male threads are adapted to engage the threaded bore of the bearing disc, a plurality of central screw ramps attached to the screw, and a plurality of central input disc ramps affixed to the input disc and adapted to engage the plurality of central screw ramps.

In another aspect, a support cage is disclosed that supports and positions a plurality of speed adjusting tiltable balls in a rolling traction transmission, which utilizes an input disc and an output disc on either side of the plurality of balls, the cage comprising; first and second flat support discs that are each a generally circular sheet having a plurality of slots extending radially inward from an outer edge, each slot having two sides, and a plurality of flat supporting spacers extending between said first and second support discs each spacer having a front side, a back side, a first end and a second end, wherein the first and second ends each have a mounting surface, wherein each mounting surface has a curved surface, and wherein the spacers are positioned angularly about the support discs between the grooves in the support discs such that the curved surfaces are aligned with the sides of the grooves.

In yet another aspect, a support leg for a ratio changing mechanism, which changes the transmission ratio in a rolling traction transmission by tilting an axle that forms the axis of rotation of a ratio-determining ball, is disclosed that comprises: an elongated body, an axle-connecting end, a cam end opposite the axle-connecting end, a front side that faces the ball and a backside that faces away from the ball, and a central support portion between the axle-connecting end and the cam end, wherein the axle-connecting end has a bore formed through it adapted to receive the axle, and wherein a convexly curved camming surface is formed on the front side of the cam end that is adapted to assist in controlling the alignment of the bore.

In some embodiments, the invention comprises a variable speed transmission having a longitudinal axis and a plurality of balls distributed radially about the longitudinal axis. Each ball has a tiltable axis about which it rotates. The transmission also includes a rotatable input disc in contact with each of the balls. The transmission has a rotatable idler coaxial about the longitudinal axis and in contact with each of the balls, wherein the idler is adapted to transfer power. Another feature of the inventive transmission is that the idler can be configured to transfer power at a higher average speed than the input disc. In some embodiments, the idler transfers power at a speed higher than the input disc in all ratios.

In yet another embodiment, the invention includes a variable speed transmission having a longitudinal axis and several spherical rollers distributed radially about the longitudinal axis, each roller is preferably fitted with a tiltable axis about which it rotates. The transmission may also include an input disc in contact with the rollers. The transmission may additionally have an idler rotatable about the longitudinal axis and in contact with each of the rollers. The inventive transmission may also comprise a transfer shaft rotatable about the longitudinal axis. The shaft may be rigidly attached to the idler, is capable of axial movement, and transfers power.

Another feature of the invention concerns a variable speed transmission having multiple transfer bearings that contact a transfer axle, are configured to roll axially along an axis parallel to the longitudinal axis, and orbit the longitudinal axis.

In some embodiments, an aspect of the invention is a variable speed transmission comprising a high speed shaft and a low speed shaft, both rotatable about the longitudinal axis, the high speed shaft transferring power at a higher speed than the low speed shaft wherein the high speed shaft contacts the transfer bearings.

In yet other embodiments, the variable speed transmission includes a high speed shaft having a plurality of longitudinal radiused grooves along axes parallel to and radial outward from the longitudinal axis. The transfer bearings may be adapted to fit into the longitudinal grooves of the high speed shaft, each longitudinal groove having a radius slightly larger than the radii of the transfer bearings.

In some embodiments, a variable speed transmission has a transfer shaft that contains a plurality of longitudinal radiused grooves along axes parallel to and radially outward from the longitudinal axis.

Another aspect of the invention relates to variable speed transmission having a longitudinal axis and an idler which is rotatable about the longitudinal axis and which is adapted to transfer power. The transmission may further include a rotatable input disc. The transmission may also have multiple spherical rollers distributed radially about the longitudinal axis, each roller having a tiltable axis about which it rotates. The roller is operationally in frictional contact with the idler and the input disc. Another aspect of the transmission concerns a bearing disc that is rotatable about the longitudinal axis and is adapted to transfer power and absorb axial force. The transmission may also include a bearing disc bearing that is rotatable about the longitudinal axis, and wherein the bearing disc bearing contacts the bearing disc and is able to absorb axial force. Another feature of the transmission relates to a rotatable case mounted about the longitudinal axis, the case being in operable contact with rollers and the bearing disc bearing. In some embodiments, the case is adapted to not transfer power.

In some embodiments, the inventive transmission may include a non-rotating output stator coaxially positioned about the longitudinal axis, the output stator positioned both inside of and outside of the case, the output stator containing at least one aperture located outside of the case, the at least one aperture configured to provide access for shifting the transmission.

In yet other embodiments, the transmission may have a non-rotating brace rigidly attached to the output stator and operably attached to a rigid structure, such as a frame.

Another embodiment of the invention disclosed herein refers to a variable speed transmission having longitudinal axis and several balls distributed radially about the longitudinal axis, each ball having a tiltable axis about which it rotates. The transmission also includes a rotatable input disc positioned adjacent to the balls and in contact with each of the balls. In some embodiments, the transmission additionally comprises an idler rotatable about the longitudinal axis and positioned radially inward of and in contact with each of the balls, the idler capable of transferring power. In some embodiments, the transmission may include a transfer shaft rotatable about the longitudinal axis and able to transfer power, the transfer shaft rigidly attached to the idler and able to move axially. The transmission may also have at least one annular shift bearing able to absorb axial force, positioned coaxially about the longitudinal axis, and able to move axially simultaneously with the transfer shaft and the idler.

In some embodiments, the inventive transmission may have a non-rotating output stator coaxially positioned about the longitudinal axis, the output stator positioned both inside of and outside of the case, the output stator containing at least one aperture located outside of the case, the at least one aperture configured to provide access for shifting the transmission. The inventive transmission may also include at least one shift pin contacting the one shift bearing, and extending through the aperture of the output stator. In other embodiments, the transmission may include a shift ring coaxially positioned about the longitudinal axis, the shift ring attached to the shift pin and able to move axially with the transfer shaft.

In additional embodiments, the invention is directed to a variable speed transmission that has a longitudinal axis and multiple balls distributed radially about the longitudinal axis. Preferably, each ball has a tiltable axis about which it rotates. The transmission may also have an input disc operationally in frictional contact with each of the balls. The transmission may include an idler adapted to transfer power, rotatable about the longitudinal axis, and in contact with each of the balls. The transmission may be configured such that an idler track and an input disc track are equal when negative gamma is one half alpha. Gamma and alpha are described below. In some embodiments, the transmission600is configured such that its ratio range is equal to the overdrive ratio of transmission100when positive gamma of each transmission is equal. In yet other embodiments, the ratio range of transmission1800is equal to the overdrive ratio of transmission100when positive gamma of each transmission is equal. In some embodiments, the average speed decrease of transmission1800remains the same as positive gamma varies. In some embodiments, the speed increase of transmission600equals the radius of the input disc divided by the radius of the idler when negative gamma is one half alpha. In other embodiments, the speed decrease of transmission1800equals the radius of the input disc divided by the radius of the idler when negative gamma is one half alpha. In yet other embodiments, the values of negative gamma do not produce as great of a rate of speed change as positive gamma values for the transmission600.

Another aspect of the inventive transmission concerns a variable speed transmission having a longitudinal axis and balls distributed radially about the longitudinal axis, each ball having a tiltable axis about which it rotates. The transmission includes an input disc, an idler, and an output disc, all configured such that each of the input disc, idler, and output disc are in operational frictional contact with each of the balls. The balls may have textured surfaces formed into their surfaces. A hard, wear resistant coating may be applied to the surfaces of the balls. The height of the textured surface is preferably 1-10 microns thick, and more preferably 0.5-5 microns thick. In some embodiments, the input and output discs also have textured surfaces. In other embodiments, the textured surface increases friction between the balls and one or both of the input and output discs. In yet other embodiments, the idler also has a textured surface. In additional embodiments, the textured surface increases the surface area of the balls. In yet other embodiments, the textured surface increases the mechanical bond between the coating and the substrate.

Yet another aspect of the invention concerns a continuously variable transmission (CVT) having a longitudinal axis and a plurality of balls distributed radially about the longitudinal axis. The CVT can additionally include a rotatable idler in contact with each of, and radially inward of, the balls. The CVT can also be configured such that a first shaft is coupled to the idler, and wherein the plurality of balls, the rotatable idler, and the first shaft are adapted to transmit power.

In one aspect, the invention relates to a shifting apparatus for a continuously variable transmission having a plurality of balls arranged radially about, and supported by, an idler. The shifting apparatus can include a shaft operationally coupled to the idler, and a lever operationally coupled to the shaft such that actuation of the lever causes an axial movement of the shaft.

Another aspect of the invention comprehends a method of operating a continuously variable transmission. The method includes providing an input disc, an output disc, a plurality of balls between and in contact with the input disc and the output disc. The method further includes contacting each of the input disc and the output disc to the balls at an angle alpha, wherein the angle alpha is the angle between a line parallel to a longitudinal axis of the CVT and a line parallel to the line of action at the point of contact between the balls and the input disc. The method can further include providing an idler, positioned radially inward of the balls, wherein the idler is configured to support the balls. In one embodiment, the method can also include configuring the CVT such that the ratio of a radius of the input disc to a radius of the idler is such that an idler track is greater than or equal to an input disc track at all gamma angles, wherein gamma is the angle defined by the tilting of an axis of rotation of the balls relative to a longitudinal axis of the CVT.

In yet another aspect, the invention relates to a wind turbine. In one embodiment, the wind turbine can include a wind turbine rotor coupled to a first shaft, a speed increasing gearbox coupled to the first shaft and to a second shaft, a continuously variable transmission (CVT) coupled to the second shaft and to a third shaft, and a generator coupled to the third shaft. In one embodiment of the wind turbine, the CVT includes an input disc operationally coupled to the second shaft, a plurality of balls driven by the input disc, and an idler configured to be driven by the plurality of the balls. In certain embodiments, the idler is operationally coupled to the third shaft.

These and other improvements will become apparent to those skilled in the art as they read the following detailed description and view the enclosed figures.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The transmissions described herein are of the type that utilize speed adjuster balls with axes that tilt as described in, for example, U.S. Pat. Nos. 6,241,636, 6,322,475, and 6,419,608, and 6,689,012. The embodiments described in these patents and those described herein typically have two sides generally separated by a variator portion, to be described below, an input side and an output side. The driving side of the transmission, which is the side that receives the torque or the rotational force into the transmission, is termed the input side, and the driven side of the transmission, or the side that transfers the torque from the transmission out of the transmission, is termed the output side. An input disc and an output disc are in contact with the speed adjuster balls. As the balls tilt on their axes, the point of rolling contact on one disc moves toward the pole or axis of the ball, where it contacts the ball at a circle of decreasing diameter, and the point of rolling contact on the other disc moves toward the equator of the ball, thus contacting the disc at a circle of increasing diameter. If the axis of the ball is tilted in the opposite direction, the input and output discs respectively experience the converse relationship. In this manner, the ratio of rotational speed of the input disc to that of the output disc, or the transmission ratio, can be changed over a wide range by simply tilting the axes of the speed adjuster balls. The centers of the balls define the border between the input side and the output side of the transmission and similar components that are located on both the input side of the balls and the output side of the balls are generally described herein with the same reference numbers. Similar components located on both the input and output sides of the transmission generally have the suffix “a” attached at the end of the reference number if they are located on the input side, and the components located on the output side of the transmission generally have the suffix “b” attached at the end of their respective reference numbers.

Referring toFIGS. 1 and 2, an embodiment of a transmission100is illustrated having a longitudinal axis11about which multiple speed adjusting balls1are radially distributed. The speed adjusting balls1of some embodiments stay in their angular positions about the longitudinal axis11, while in other embodiments the balls1are free to orbit about the longitudinal axis11. The balls1are contacted on their input side by an input disc34and on their output side by an output disc101. The input and output discs34,101are annular discs extending from an inner bore near the longitudinal axis11on their respective input and output sides of the balls1to a radial point at which they each make contact with the balls1. The input and output discs34,101each have a contact surface that forms the contact area between each disc34and101, and the balls1. In general, as the input disc34rotates about the longitudinal axis11, each portion of the contact area of the input disc34rotates and sequentially contacts each of the balls1during each rotation. This is similar for the output disc101as well.

The input disc34and the output disc101can be shaped as simple discs or can be concave, convex, and cylindrical or any other shape, depending on the configuration of the input and output desired. In one embodiment the input and output discs are spoked to make them lighter for weight sensitive applications. The rolling contact surfaces of the discs where they engage the speed adjuster balls can have a flat, concave, convex, or other shaped profile, depending on the torque and efficiency requirements of the application. A concave profile where the discs contact the balls decreases the amount of axial force required to prevent slippage while a convex profile increases efficiency.

Additionally, the balls1all contact an idler18on their respective radially innermost point. The idler18is a generally cylindrical component that rests coaxially about the longitudinal axis11and assists in maintaining the radial position of the balls1. With reference to the longitudinal axis11of many embodiments of the transmission, the contact surfaces of the input disc34and the output disc101can be located generally radially outward from the center of the balls1, with the idler18located radially inward from the balls1, so that each ball1makes three-point contact with the idler18, the input disc34, and the output disc101. The input disc34, the output disc101, and the idler18can all rotate about the same longitudinal axis11in many embodiments, and are described in fuller detail below.

Due to the fact that the embodiments of transmissions100described herein are rolling traction transmissions, in some embodiments, high axial forces are required to prevent slippage of the input disc34and output disc101at the ball1contacts. As axial force increases during periods of high torque transfer, deformation of the contact patches where the input disc34, the output disc101, and the idler18contact the balls1becomes a significant problem, reducing efficiency and the life of these components. The amount of torque that can be transferred through these contact patches is finite and is a function of the yield strength of the material from which the balls1, the input disc,34, the output disc101, and the idler18are made. The friction coefficient of the balls1, the input disc,34, the output disc101, and the idler18has a dramatic effect on the amount of axial force required to transfer a given amount of torque and thus greatly affects the efficiency and life of the transmission. The friction coefficient of the rolling elements in a traction transmission is a very important variable affecting performance.

Certain coatings may be applied to the surfaces of the balls1, the input disc,34, the output disc101, and the idler18to improve their performance. In fact, such coatings can be used advantageously on the rolling contacting elements of any rolling traction transmission to achieve the same added benefits that are achieved for the embodiments of transmissions described herein. Some coatings have the beneficial effect of increasing the friction coefficient of the surfaces of these rolling elements. Some coatings have a high friction coefficient and also display a variable coefficient of friction, which increases as axial force increases. A high friction coefficient allows less axial force to be required for a given torque, thereby increasing efficiency and life of the transmission. A variable coefficient of friction increases the maximum torque rating of the transmission by decreasing the amount of axial force required to transfer this maximum torque.

Some coatings, such as ceramics and cermets, possess excellent hardness and wear properties, and can greatly extend the life of the highly loaded rolling elements in a rolling traction transmission. A ceramic coating such as silicon nitride can have a high friction coefficient, a variable coefficient of friction which increases as axial force increases, and can also increase the life of the balls1, the input disc,34, the output disc101, and the idler18when applied to the surfaces of these components in a very thin layer. The coating thickness depends on the material used for the coating and can vary from application to application but typically is in the range of 0.5 microns to 2 microns for a ceramic and 0.75 microns to 4 microns for a cermet.

The process used to apply the coating is important to consider when the balls1, the input disc,34, the output disc101, and the idler18are made from hardened steel, which is the material used in many embodiments of the transmissions described herein. Some processes used to apply ceramics and cermets require high temperatures and will lower the hardness of the balls1, the input disc,34, the output disc101, and the idler18, harming performance and contributing to premature failure. A low temperature application process is desirable and several are available, including low temperature vacuum plasma, DC pulsed reactive magnetron sputtering, plasma-enhanced chemical vapor deposition (PE-CVD), unbalanced magnetron physical vapor deposition, and plating. The plating process is attractive due to its low cost and because a custom bath can be created to achieve desired coating properties. Immersing the rolling elements in a bath of silicon carbide or silicon nitride with co-deposited electroless nickel or electroplated nickel with silicon carbide or silicon nitride is a low temperature solution that is well suited for high volume production. It should be noted that other materials can be used in addition to those mentioned. With this application process, the parts are contained in a cage, immersed in the bath, and shaken so that the solution contacts all surfaces. Thickness of the coating is controlled by the length of time that the components are immersed in the bath. For instance, some embodiments will soak the components using silicon nitride with co-deposited electroless nickel for four (4) hours to achieve the proper coating thickness, although this is just an example and many ways to form the coating and control its thickness are known and can be used taking into account the desired properties, the desired thickness and the substrate or base metal of which the components are made.

FIGS. 1,2, and3illustrate an embodiment of a continuously variable transmission100that is shrouded in a case40which protects the transmission100, contains lubricant, aligns components of the transmission100, and absorbs forces of the transmission100. A case cap67can, in certain embodiments, cover the case40. The case cap67is generally shaped as a disc with a bore through its center through which an input shaft passes. The case cap67has a set of threads at its outer diameter that thread into a corresponding set of threads on the inner diameter of the case40. Although in other embodiments, the case cap67can be fastened to the case40or held in place by a snap ring and corresponding groove in the case40, and would therefore not need to be threaded at its outer diameter. In embodiments utilizing fasteners to attach the case cap67, the case cap67extends to the inside diameter of the case40so that case fasteners (not shown) used to bolt the case40to the machinery to which the transmission100is attached can be passed through corresponding holes in the case cap67. The case cap67of the illustrated embodiment has a cylindrical portion extending from an area near its outer diameter toward the output side of the transmission100for additional support of other components of the transmission100.

At the heart of the illustrated transmission100embodiment is a plurality of balls1that are typically spherical in shape and are radially distributed substantially evenly or symmetrically about the centerline, or longitudinal axis11of rotation of the transmission100. In the illustrated embodiment, eight balls1are used. However, it should be noted that more or fewer balls1could be used depending on the use of the transmission100. For example, the transmission may include 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or more balls. The provision for more than 3, 4, or 5 balls can more widely distribute the forces exerted on the individual balls1and their points of contact with other components of the transmission100and can also reduce the force necessary to prevent the transmission100from slipping at the ball1contact patches. Certain embodiments in applications with low torque but a high transmission ratio use few balls1of relatively larger diameters, while certain embodiments in applications with high torque and a high transmission ratio can use more balls1or relatively larger diameters. Other embodiments, in applications with high torque and a low transmission ratio and where high efficiency is not important, use more balls1of relatively smaller diameters. Finally, certain embodiments, in applications with low torque and where high efficiency is not important, use few balls1of relatively smaller diameters.

Ball axles3are inserted through holes that run through the center of each of the balls1to define an axis of rotation for each of the balls1. The ball axles3are generally elongated shafts over which the balls1rotate, and have two ends that extend out of either side of the hole through the balls1. Certain embodiments have cylindrically shaped ball axles3, although any shape can be used. The balls1are mounted to freely rotate about the ball axles3.

In certain embodiments, bearings (not separately illustrated) are utilized to reduce the friction between the outer surface of the ball axles3and the surface of the bore through the corresponding ball1. These bearings can be any type of bearings situated anywhere along the contacting surfaces of the balls1and their corresponding ball axles3, and many embodiments will maximize the life and utility of such bearings through standard mechanical principles common in the design of dynamic mechanical systems. In some of these embodiments, radial bearings are located at each end of the bore through the balls1. These bearings can incorporate the inner surface of the bore or the outer surface of the ball axles3as their races, or the bearings can include separate races that fit in appropriate cavities formed in the bore of each ball1and on each ball axle3. In one embodiment, a cavity (not shown) for a bearing is formed by expanding the bore through each ball1at least at both ends an appropriate diameter such that a radial bearing, roller, ball or other type, can be fitted into and held within the cavity thus formed. In another embodiment, the ball axles3are coated with a friction reducing material such as babbit, Teflon or other such material.

Many embodiments also minimize the friction between the ball axles3and the balls1by introducing lubrication in the bore of the ball axles3. The lubrication can be injected into the bore around the ball axles3by a pressure source, or it can be drawn into the bore by the rifling or helical grooves formed on the ball axles3themselves. Further discussion of the lubrication of the ball axles3is provided below.

InFIG. 1, the axes of rotation of the balls1are shown tilted in a direction that puts the transmission in a high ratio, wherein the output speed is greater than the input speed. If the ball axles3are horizontal, that is parallel to the main axis of the transmission100, the transmission100is in a 1:1 input rotation rate to output rotation rate ratio, wherein the input and output rotation speeds are equal. InFIG. 2, the axes of rotation of the balls1are shown tilted in a direction where the transmission100is in a low ratio, meaning the output rotation speed is slower than the input rotation speed. For the purpose of simplicity, only the parts that change position or orientation when the transmission100is shifted are numbered inFIG. 2.

FIGS. 1,2,4, and5illustrate how the axes of the balls1can be tilted in operation to shift the transmission100. Referring toFIG. 5, a plurality of legs2, which in most embodiments are generally struts, are attached to the ball axles3near each of the ends of the ball axles3that extend beyond the ends of the holes bored through the balls1. Each leg2extends from its point of attachment to its respective ball axle3radially inward toward the axis of the transmission100. In one embodiment, each of the legs2has a through bore that receives a respective end of one of the ball axles3. The ball axles3preferably extend through the legs2such that they have an end exposed beyond each leg2. In the illustrated embodiments, the ball axles3advantageously have rollers4coaxially and slidingly positioned over the exposed ends of the ball axles3. The rollers4are generally cylindrical wheels fitted over the ball axles3outside of and beyond the legs2and rotate freely about the ball axles3. The rollers4can be attached to the ball axles3via spring clips or other such mechanism, or they can ride freely over the ball axles3. The rollers4can be radial bearings for instance, where the outer races of the bearings form the wheel or rolling surface. As illustrated inFIGS. 1 and 7, the rollers4and the ends of the ball axles3fit inside grooves86formed by or in a pair of stators80a,80b.

The stators80a,80bof one embodiment are illustrated inFIGS. 5 and 7. The illustrated input stator80aand output stator80bare generally in the form of parallel discs annularly located about the longitudinal axis11of the transmission on either side of the balls1. The stators80a,80bof many embodiments are comprised of input stator discs81aand output stator discs81b, respectively, which are generally annular discs of substantially uniform thickness with multiple apertures to be discussed further below. Each input and output stator disc81a,81bhas a first side that faces the balls1and a second side that faces away from the balls1. Multiple stator curves82are attached to the first side of the stator discs81a,81b. The stator curves82are curved surfaces attached or affixed to the stator discs81a,81bthat each have a concave face90facing toward the balls1and a convex face91facing away from the balls1and contacting their respective stator discs81. In some embodiments, the stator curves82are integral with the stator discs81a,81b. The stator curves82of many embodiments have a substantially uniform thickness and have at least one aperture (not separately shown) used to align and attach the stator curves82to each other and to the stator discs81. The stator curves82of many embodiments, or the stator discs81a,81bwhere integral parts are used, include a slot710that accepts a flat spacer83, which allows further positioning and alignment of the stator curves82and stator discs81a,81b. The flat spacers83are generally flat and generally rectangular pieces of rigid material that extend between and interconnect the input stator80aand the output stator80b. The flat spacers83fit within the slots710formed in the stator curves82. In the illustrated embodiment, the flat spacers83are not fastened or otherwise connected to the stator curves82; however, in some embodiments the flat spacers83are attached to the stator curves82by welding, adhesive, or fastening.

Also illustrated inFIG. 7, multiple cylindrical spacers84, of a generally cylindrical shape with bores at least in each end, are radially positioned inside of the flat spacers83and also connect and position the stator discs81and stator curves82. The bores of the cylindrical spacers84accept one spacer fastener85at each end. The spacer fasteners85are designed to clamp and hold the stator discs81a,81b, the stator curves82, the flat spacers83, and the cylindrical spacers84together, which collectively form the cage89. The cage89maintains the radial and angular positions of the balls1and aligns the balls1with respect to one another.

The rotational axes of the balls1are changed by moving either the input-side or output-side legs2radially out from the axis of the transmission100, which tilts the ball axles3. As this occurs, each roller4fits into and follows a groove86, which is slightly larger than the diameter of the roller4, and is formed by the space between each pair of adjacent stator curves82. The rollers4therefore roll along the surface of the sides92,93of the stator curves82, a first side92and a second side93for each stator curve82, in order to maintain the plane of movement of the ball axles3in line with the longitudinal axis11of the transmission100. In many embodiments, each roller4rolls on a first side92of the stator curve82on the input side of the transmission100and on the corresponding first side92of the corresponding output stator curve82. Typically in such embodiments, the forces of the transmission100prevent the rollers4from contacting the second side93of the stator curves82in normal operation. The rollers4are slightly smaller in diameter than the width of the grooves86, forming a small gap between the edges of the grooves86and the circumference of each corresponding roller.

If the opposing sets of stator curves82on the input stator80aand output stator80bwere in perfect alignment, the small gap between the circumferences of the rollers4and the grooves86would allow the ball axles to slightly tilt and become misaligned with the longitudinal axis11of the transmission100. This condition produces sideslip, a situation where the balls axles3are allowed to slightly move laterally, which lowers overall transmission efficiency. In some embodiments, the stator curves82on the input and output sides of the transmission100may be slightly offset from each other so that the ball axles3remain parallel with the axis of the transmission100. Any tangential force, mainly a transaxial force, the balls1may apply to the ball axles3is absorbed by the ball axles3, the rollers4and the first sides92,93. As the transmission100is shifted to a lower or higher transmission ratio by changing the rotational axes of the balls1, each one of the pairs of rollers4, located on the opposite ends of a single ball axle3, move in opposite directions along their respective corresponding grooves86by rolling up or down a respective side of the groove86.

Referring toFIGS. 1 and 7, the cage89can be rigidly attached to the case40with one or more case connectors167. The case connectors167extend generally perpendicularly from the radial outermost part of the flat spacers83. The case connectors167can be fastened to the flat spacers83or can be formed integrally with the flat spacers83. The outside diameter formed roughly by the outsides of the case connectors167is substantially the same dimension as the inside diameter of the case40and holes in both the case40and case connectors167provide for the use of standard or specialty fasteners, which rigidly attach the case connectors167to the case40, thus bracing and preventing the cage40from moving. The case40has mounting holes providing for the attachment of the case40to a frame or other structural body. In other embodiments, the case connectors167can be formed as part of the case40and provide a location for attachment of the flat spacers83or other cage89component in order to immobilize the cage89.

FIGS. 1,5, and7illustrate an embodiment including a pair of stator wheels30attached to each of the legs2that roll on the concave face90of the curved surfaces82along a path near the edge of the sides92,93. The stator wheels30are attached to the legs2generally in the area where the ball axles3pass through the legs2. The stator wheels30can be attached to the legs2with stator wheel pins31, which pass through a bore through the legs2that is generally perpendicular to the ball axles3, or by any other attachment method. The stator wheels30are coaxially and slidingly mounted over the stator wheel pins31and secured with standard fasteners, such as snap rings for example. In some embodiments, the stator wheels30are radial bearings with the inner race mounted to the stator wheel pins31and the outer race forming the rolling surface. In certain embodiments, one stator wheel30is positioned on each side of a leg2with enough clearance from the leg2to allow the stator wheels30to roll radially along the concave faces90, with respect to the longitudinal axis11, when the transmission100is shifted. In certain embodiments, the concave faces90are shaped such that they are concentric about a radius from the longitudinal axis11formed by the center of the balls1.

Still referring toFIGS. 1,5, and7, guide wheels21are illustrated that can be attached to the end of the legs2that are nearest the longitudinal axis11. In the illustrated embodiment, the guide wheels21are inserted into a slot formed in the end of the legs2. The guide wheels21are held in place in the slots of the legs21with guide wheel pins22, or by any other attachment method. The guide wheels21are coaxially and slidingly mounted over the guide wheel pins22, which are inserted into bores formed in the legs2on each side of the guide wheels21and perpendicular to the plane of the slot. In some embodiments, the legs2are designed to elastically deflect relatively slightly in order to allow for manufacturing tolerances of the parts of the transmission100. The ball1, the legs2, the ball axle3, the rollers4, the stator wheels30, the stator wheel pins31, the guide wheels21, and the guide wheel pins22collectively form the ball/leg assembly403seen inFIG. 5.

Referring to the embodiment illustrated inFIGS. 4,6, and7, shifting is actuated by rotating a rod10that is positioned outside of the case40. The rod10is utilized to wrap an unwrap a flexible input cable155aand a flexible output cable155bthat are attached to, at their respective first ends, and wrapped around the rod10, in opposite respective directions. In some embodiments, the input cable155ais wrapped counter-clockwise around the rod10and the output cable155bis wrapped clockwise around the rod10, when looking from right to left as the rod10is illustrated inFIG. 6. Both the input cable155aand the output cable155bextend through holes in the case40and then through the first end of an input flexible cable housing151a, and an output flexible cable housing151b. The input flexible cable housing151aand the output flexible cable housing151bof the illustrated embodiment are flexible, elongated tubes that guide the input cable155aand output cable155bradially inward toward the longitudinal axis11, then longitudinally out through holes in the stator discs81a,81b, and then again radially inward where the second end of the input and output flexible cable housings151a,151bare inserted into and attach to the first end of input and output rigid cable housings153a,153b,respectively.

The input and output rigid cable housings153a,153b, are inflexible tubes through which the cables155a,155bpass and are guided radially inward from the second ends of the flexible cable housings151a,151band then direct the cables155a,155blongitudinally through holes in the stator discs81a,81band toward a second end of the rigid cable housings153a,153bnear the idler18. In many embodiments, the cables155a,155bare attached at their second ends to an input shift guide13a, and an output shift guide13b(described further below) with conventional cable fasteners, or other suitable attachment means. As will be discussed further below, the shift guides13a,13bposition the idler18axially along the longitudinal axis11and position the legs3radially, thereby changing the axes of the balls1and the ratio of the transmission100.

If the rod10is rotated counter-clockwise, relative to the axis of the rod10from right to left as illustrated inFIG. 6, by the user, either manually or assisted with a power source, the input cable155aunwinds from the rod10and the output cable155bwinds onto the rod10. Therefore, the second end of the output cable155bapplies a tension force to the output shift guide13band the input cable155ais unwinding a commensurate amount from the rod10. This moves the idler18axially toward the output side of the transmission100and shifts the transmission100toward low.

Still referring toFIGS. 4,5, and7, the illustrated shift guides13a,13b, are each generally of the form of an annular ring with inside and outside diameters, and are shaped so as to have two sides. The first side is a generally straight surface that dynamically contacts and axially supports the idler18via two sets of idler bearings17a,17b, which are each associated with a respective shift guide13a,13b. The second side of each shift guide13a,13b, the side facing away from the idler18, is a cam side that transitions from a straight or flat radial surface14, towards the inner diameter of the shift guides13a,13b, to a convex curve97towards the outer diameter of the shift guides13a,13b. At the inner diameter of the shift guides13a,13ba longitudinal tubular sleeve417a,417bextends axially toward the opposing shift guide13a,13bin order to mate with the tubular sleeve417a,417bfrom that shift guide13a,13b. In some embodiments, as illustrated inFIG. 4, the tubular sleeve417aof the input side shift guide13ahas part of its inner diameter bored out to accept the tubular sleeve417bof the output shift guide13b. Correspondingly, a portion of the outer diameter of the tubular sleeve417bhas been removed to allow a portion of that tubular sleeve417ato be inserted into the tubular sleeve417b, and vice versa. This provides additional stability to the shift guides13a,13bof such embodiments.

The cross section side view of the shift guides13a,13billustrated inFIG. 4shows that, in this embodiment, the flat surface14profile of the side facing away from the is perpendicular to the longitudinal axis11up to a radial point where the guide wheels21contact the shift guides13a,13b, if the ball axles3are parallel with the longitudinal axis11. From this point moving out toward the perimeter of the shift guide13a,13b, the profile of the shift guides13a,13bcurves in a convex shape. In some embodiments, the convex curve97of a shift guide13a,13bis not a radius but is composed of multiple radii, or is shaped hyperbolically, asymptotically or otherwise. As the transmission100is shifted toward low, the input guide wheels21aroll toward the longitudinal axis11on the flat portion14of shift guide13a, and the output guide wheels21broll on the convex curved97portion of the shift guide13baway from the longitudinal axis11. The shift guides13a,13b, can be attached to each other by either threading the tubular sleeve of the input shift guide13awith male threads and the tubular sleeve of the output sleeve13bwith female threads, or vice versa, and threading the shift guides13a,13b, together. One shift guide13a,13b, either the input or output, can also be pressed into the other shift guide13a,13b. The shift guides13a,13bcan also be attached by other methods such as glue, metal adhesive, welding or any other means.

The convex curves97of the two shift guides13a,13b, act as cam surfaces, each contacting and pushing the multiple guide wheels21. The flat surface14and convex curve97of each shift guide13a,13bcontact the guide wheels21so that as the shift guides13a,13b, move axially along the longitudinal axis11, the guide wheels21ride along the shift guide13a,13bsurface14,97in a generally radial direction forcing the leg2radially out from, or in toward, the longitudinal axis11, thereby changing the angle of the ball axle3and the rotational axis of the associated ball1.

Referring toFIGS. 4 and 7, the idler18of some embodiments is located in a trough formed between the first sides and the sleeve portions of the shift guides13a,13b, and thus moves in unison with the shift guides13a,13b. In certain embodiments, the idler18is generally tubular and of one outside diameter and is substantially cylindrical along the central portion of its inside diameter with an input and output idler bearing17a,17b, on each end of its inside diameter. In other embodiments, the outer diameter and inside diameters of the idler18can be non-uniform and can vary or be any shape, such as ramped or curved. The idler18has two sides, one near the input stator80a, and one near the output stator80b.

The idler bearings17a,17bprovide rolling contact between the idler18and the shift guides13a,13b. The idler bearings17a,17bare located coaxially around the sleeve portion of the shift guides13a,13b, allowing the idler18to freely rotate about the axis of the transmission100. A sleeve19is fit around the longitudinal axis11and fitting inside the inside diameters of the shift guides13a,13b. The sleeve19is a generally tubular component that is held in operable contact with an inside bearing race surface of each of the shift guides13a,13bby an input sleeve bearing172aand an output sleeve bearing172b. The sleeve bearings172a,172b, provide for rotation of the sleeve19by rolling along an outer bearing race complimentary to the races of the shift guides13a,13b. The idler18, the idler bearings17a,17b, the sleeve19, the shift guides13a,13b, and the sleeve bearings172a,172bcollectively form the idler assembly402, seen inFIG. 4.

Referring toFIGS. 4,7, and8, the sleeve19of some embodiments has its inside diameter threaded to accept the threaded insertion of an idler rod171. The idler rod171is a generally cylindrical rod that lies along the longitudinal axis11. In some embodiments, the idler rod171is threaded at least partially along its length to allow insertion into the sleeve19. The first end of the idler rod171, which faces the output side of the transmission100, is preferably threaded through the sleeve19and extends out past the output side of the sleeve19where it is inserted into the inside diameter of the output disc101.

As illustrated inFIG. 8, the output disc101in some embodiments is generally a conical disc that is spoked to reduce weight and has a tubular sleeve portion extending from its inner diameter axially toward the output side of the transmission100. The output disc101transfers the output torque to a drive shaft, wheel, or other mechanical device. The output disc101contacts the balls1on their output side and rotates at a speed different than the input rotation of the transmission at ratios other than 1:1. The output disc101serves to guide and center the idler rod171at its first end so that the sleeve19, idler18, and shift guides13a,13bstay concentric with the axis of the transmission100. Alternately, an annular bearing (not shown) may be positioned over the idler rod171, between the idler rod171and the inside diameter of the output disc101, to minimize friction. The idler rod171, sleeve19, shift guides13a,13b, and idler18are operably connected, and all move axially in unison when the transmission100is shifted.

Referring toFIG. 2, a conical spring133, positioned between the input shift guide13aand stator80abiases the shifting of the transmission100toward low. Referring toFIG. 1, output disc bearings102, which contact a bearing race near the perimeter of the output disc101, absorb and transfer axial force generated by the transmission100to the case40. The case40has a corresponding bearing race to guide the output disc bearings102.

Referring toFIGS. 4,5, and7, the limits of the axial movement of the shift guides13a,13bdefine the shifting range of the transmission100. Axial movement is limited by inside faces88a,88b, on the stator discs81a,81b, which the shift guides13a,13b, contact. At an extreme high transmission ratio, shift guide13acontacts the inside face88aon the input stator disc81a, and at an extreme low transmission ratio, the shift guide13bcontacts the inside face88bon the output stator disc81b. In many embodiments, the curvature of the convex curves97of the shift guides13a,13b, is functionally dependent on the distance from the center of a ball1to the center of the guide wheel21, the radius of the guide wheel21, the angle between lines formed between the two guide wheels21and the center of the ball1, and the angle of tilt of the ball1axis. An example of such a relationship is described below, with respect toFIGS. 25,26and27.

Now referring to embodiments illustrated byFIGS. 1,5, and7, one or more stator wheels30can be attached to each leg2with a stator wheel pin31that is inserted through a hole in each leg2. The stator wheel pins31are of the proper size and design to allow the stator wheels30to rotate freely over each stator wheel pin31. The stator wheels30roll along the concave curved surfaces90. The stator wheels30provide axial support to prevent the legs2from moving axially and also to ensure that the ball axles3tilt easily when the transmission100is shifted.

Referring toFIGS. 1 and 7, a spoked input disc34, located adjacent to the stator80a, partially encapsulates but generally does not contact the stator80a. The input disc34may have two or more spokes or may be a solid disc. The spokes reduce weight and aid in assembly of the transmission100. In other embodiments, a solid disc can be used. The input disc34has two sides, a first side that contacts with the balls1, and a second side that faces opposite the first side. The input disc34is generally an annular disk that fits coaxially over, and extends radially from, a set of female threads or nut37at its inner diameter. The outside diameter of the input disc34is designed to fit within the case40, if the case40used is the type that encapsulates the balls1and the input disc34and mounts to a rigid support structure116such as a chassis or frame with conventional bolts, which are inserted through bolt holes in a flange on the case40. As mentioned above, the input disc34is in rotating contact with the balls1along a circumferential ramped or bearing contact surface on a lip of the first side of the input disc34, the side facing the balls1. As also mentioned above, some embodiments of the input disc34have a set of female threads37, or a nut37, inserted into its inside diameter, and the nut37is threaded over a screw35, thereby engaging the input disc34with the screw35.

Referring toFIGS. 1 and 4, the screw35is attached to and rotated by a drive shaft69. The drive shaft69is generally cylindrical and has an inner bore, a first end facing axially towards the output side, a second end facing axially toward the input side, and a generally constant diameter. At the first end, the drive shaft69is rigidly attached to and rotated by the input torque device, usually a gear, a sprocket, or a crankshaft from a motor. The drive shaft69has axial splines109extending from its second end to engage and rotate a corresponding set of splines formed on the inside diameter of the screw35. A set of central drive shaft ramps99, which on a first side is generally a set of raised inclined surfaces on an annular disk that is positioned coaxially over the drive shaft69, have mating prongs that mate with the splines109, are rotated by the drive shaft69, and are capable of moving axially along the drive shaft69. A pin ring195contacts a second side of the central drive shaft ramps99. The pin ring195is a rigid ring that is coaxially positioned over the idler rod171, is capable of axial movement and has a transverse bore that functions to hold an idler pin196in alignment with the idler rod171. The idler pin196is an elongated rigid rod that is slightly longer than the diameter of the pin ring195and which is inserted through an elongated slot173in the idler rod171and extends slightly beyond the pin ring195at both its first and second ends when it is inserted into the bore of the pin ring195.

The elongated slot173allows for axial movement of the idler rod171to the right, when viewed as illustrated inFIG. 1, without contacting the pin196when the transmission100is shifted from 1:1 toward high. However, when the transmission100is shifted from 1:1 toward low, the side on the input end of the elongated slot173contacts the pin196, which then operably contacts the central drive shaft ramps99via the pin ring195. The idler rod171is thus operably connected to the central drive shaft ramps99when the transmission is between 1:1 and low so that when the idler rod171moves axially the central drive shaft ramps99also move axially in conjunction with the idler rod171. The ramp surfaces of the central drive shaft ramps99can be helical, curved, linear, or any other shape, and are in operable contact with a set of corresponding central bearing disc ramps98. The central bearing disc ramps98have ramp faces that are complimentary to and oppose the central drive shaft ramps99. On a first side, facing the output side of the transmission100, the central bearing disc ramps98face the central drive shaft ramps99and are contacted and driven by the central drive shaft ramps99.

The central bearing disc ramps98are rigidly attached to a bearing disc60, a generally annular disc positioned to rotate coaxially about the longitudinal axis11. The bearing disc60has a bearing race near its perimeter on its side that faces away from the balls1that contacts a bearing disc bearing66. The bearing disc bearing66is an annular thrust bearing at the perimeter of the bearing disc60and is positioned between the bearing disc60and the case cap67. The bearing disc bearing66provides axial and radial support for the bearing disc60and in turn is supported by a bearing race on a case cap67, which acts with the case40to partially encapsulate the inner parts of the transmission100.

Referring toFIG. 1, the case cap67is generally an annular disc extending from the drive shaft69having a tubular portion extending toward the output end from at or near its perimeter and also having a bore through its center. The case cap67absorbs axial and radial forces produced by the transmission100, and seals the transmission100, thereby preventing lubricant from escaping and contamination from entering. The case cap67is stationary and, in some embodiments, is rigidly attached to the case40with conventional fastening methods or can have male threads on its outside diameter, which mate with corresponding female threads on the inside diameter of the case40. As was mentioned above, the case cap67has a bearing race that contacts the bearing disc bearing66near the perimeter of the bearing disc60that is located at the inside of the output end of the tubular extension from the case cap67. The case cap67also has a second bearing race facing the output side located near the inside diameter of its annular portion that mates with a drive shaft bearing104. The drive shaft bearing104is a combination thrust and radial bearing that provides axial and radial support to the drive shaft69. The drive shaft69has a bearing race formed on its outside diameter facing the input side that mates with the drive shaft bearing104, which transfers the axial force produced by the screw35to the case cap67. An input bearing105, adds support to the drive shaft69. The input bearing105is coaxially positioned over the drive shaft69and mates with a third race on the inside diameter of the case cap67facing the input side of the transmission100. A cone nut106, a generally cylindrical threaded nut with a bearing race designed to provide a running surface for the input bearing105, is threaded over the drive shaft69and supports the input bearing105.

Referring to the embodiment illustrated inFIG. 1, a set of multiple perimeter ramps61, generally forming a ring about the longitudinal axis11, are rigidly attached to the bearing disc60. The perimeter ramps61are multiple inclined surfaces that are positioned radially about the longitudinal axis11and are positioned against or formed on the bearing disc60and face the output side. The inclined surfaces can be curved, helical, linear, or another shape and each one creates a wedge that produces and axial force that is applied to one of multiple ramp bearings62. The ramp bearings62are spherical but can be cylindrical, conical, or another geometric shape, and are housed in a bearing cage63. The bearing cage63of the illustrated embodiment is generally ring shaped with multiple apertures that contain the individual ramp bearings62. A set of input disc ramps64are rigidly attached to, or formed as part of, the input disc34. The input disc ramps64in some embodiments are complimentary to the perimeter ramps62with the ramps facing toward the input side. In another embodiment, the input disc ramps64are in the form of a bearing race that aligns and centers the ramp bearings62radially. The ramp bearings62respond to variations in torque by rolling up or down the inclined faces of the perimeter ramps61and the input disc ramps64.

Referring now toFIGS. 1 and 4, an axial force generator160is made up of various components that create an axial force that is generated and is applied to the input disc34to increase the normal contact force between the input disc34and the balls1, which is a component in the friction the input disc34utilizes in rotating the balls1. The transmission100produces sufficient axial force so that the input disc34, the balls1, and the output disc101do not slip, or slip only an acceptable amount, at their contact points. As the magnitude of torque applied to the transmission100increases, an appropriate amount of additional axial force is required to prevent slippage. Furthermore, more axial force is required to prevent slippage in low than in high or at a 1:1 speed ratio. However, providing too much force in high or at 1:1 will shorten the lifespan of the transmission100, reduce efficiency, and/or necessitate larger components to absorb the increased axial forces.

Ideally, the axial force generator160will vary the axial force applied to the balls1as the transmission100is shifted and also as torque is varied. In some embodiments, the transmission100accomplishes both these goals. The screw35is designed and configured to provide an axial force that is separate and distinct from that produced by the perimeter ramps61. In some embodiments, the screw35produces less axial force than the perimeter ramps61, although in other versions of the transmission100, the screw35is configured to produce more force than the perimeter ramps61. Upon an increase in torque, the screw35rotates slightly farther into the nut37to increase axial force by an amount proportional to the increase in torque.

If the transmission100is in a 1:1 ratio and the user or vehicle shifts into a lower speed, the idler rod171, moves axially toward the input side, along with the sleeve19, sleeve bearings172, shift guides13a,13b, and idler18. The idler rod171contacts the central drive shaft ramps99through the pin196and pin ring195, causing the central drive shaft ramps99to move axially toward the output side. The ramped surfaces of the central drive shaft ramps99contact the opposing ramped surfaces of the central bearing disc ramps98, causing the central bearing disc ramps98to rotate the bearing disc60and engage the perimeter ramps61with the ramp bearings62and the input disc ramps64. The central drive shaft ramps99and the central bearing disc ramps98perform a torque splitting function, shifting some of the torque from the screw35to the perimeter ramps61. This increases the percentage of transmitted torque that is directed through the perimeter ramps61, and due to the fact that the perimeter ramps61are torque sensitive as described above, the amount of axial force that is generated increases.

Still referring toFIGS. 1 and 4, when shifting into low, the idler18moves axially towards the output side, and is pulled toward low by a reaction of forces in the contact patch. The farther the idler18moves toward low, the stronger it is pulled. This “idler pull,” which increases with an increase in normal force across the contact as well as shift angle, also occurs when shifting into high. The idler pull occurs due to a collection of transverse forces acting in the contact patch, the effect of which is called spin. Spin occurs at the three contact patches, the points of contact where the balls contact the input disc34, the output disc101, and the idler18. The magnitude of the resultant forces from spin at the contact between the idler18and the balls1is minimal in comparison to that of the balls1and input and output discs34,101. Due to the minimal spin produced at the contact patch of the idler18and ball1interface, this contact patch will be ignored for the following explanation. Spin can be considered an efficiency loss in the contact patches at the input disc34and ball1and also at the output disc101and ball1.

Spin produces a transverse force perpendicular to the rolling direction of the balls1and discs34,101. At a 1:1 ratio the transverse forces produced by spin, or contact spin, at the input and output contact patches are equal and opposite and are essentially cancelled. There is no axial pull on the idler18in this condition. However, as the transmission100is shifted toward low for example, the contact patch at the input disc34and ball1moves farther from the axis or pole of the ball1. This decreases spin as well as the transverse forces that are produced perpendicular to the rolling direction. Simultaneously the output disc101and ball1contact patch moves closer to the axis or pole of the ball1, which increases spin and the resultant transverse force. This creates a situation where the transverse forces produced by spin on the input and output sides of the transmission100are not equal and because the transverse force on the output contact is greater, the contact patch between the output disc101and ball1moves closer to the axis of the ball1. The farther the transmission100is shifted into low the stronger the transverse forces in the contacts become that are exerted on the ball1. The transverse forces caused by spin on the ball1exert a force in the opposite direction when shifting into high. The legs2attached to the ball axles3transfer the pull to the shift guides13a,13b, and because the shift guides13a,13b, are operably attached to the idler18and sleeve19, an axial force is transferred to the idler rod171. As the normal force across the contact increases, the influence of contact spin increases at all ratios and efficiency decreases.

Still referring toFIGS. 1 and 4, as the transmission100is shifted into low, the pull transferred to the idler rod171results in an axial force toward the left, as viewed inFIG. 1, which causes the input torque to shift from the screw35to the perimeter ramps61. As the transmission100is shifted into extreme low, the idler rod171pulls more strongly, causing relative movement between the central drive shaft ramps99and the central bearing disc ramps98and shifts even more torque to the perimeter ramps61. This reduces the torque transmitted through the screw35and increases the torque transmitted through the perimeter ramps61, resulting in an increase in axial force.

Referring now toFIGS. 9 and 10, an alternative embodiment of the transmission100is disclosed. For simplicity, only the differences between the transmission600and the transmission100will be described. The transmission600is capable of increasing or decreasing speed in addition to varying speed. Referring toFIG. 9, two vertical dashed lines at the top and bottom of the transmission600and positioned at the center of the balls1, denote high speed and low speed sides of the transmission600. Where an increase in speed through the transmission600is desired, the low speed shaft608accepts input from a motor, human powered device, or other torque generating means. In some embodiments, the low speed shaft608is hollow and has a keyway formed on its interior diameter to accommodate a mating shaft inserted into its bore. In other embodiments, the low speed shaft608can be solid and formed integral to the torque generating device. In still other embodiments the low speed shaft608can be threaded, pinned, welded, glued, or joined with conventional fasteners such as screws to the torque generating means. The low speed shaft608material can be steel, aluminum, titanium, plastic, or any other suitable material for the intended application. The low speed shaft608rotates about a longitudinal axis12and is supported and located by the input bearing105and the low speed shaft bearing604. In some embodiments the low speed shaft bearing604is a radial bearing coaxially positioned in the inside diameter of the low speed shaft608. In other embodiments the low speed shaft bearing604is an angular contact bearing.

Still referring toFIGS. 9 and 10, the low speed shaft608is rigidly attached to the bearing disc60. In some embodiments, the bearing disc60is pressed over the outside diameter of the low speed shaft608with an interference press fit. In other embodiments the bearing disc60can be keyed, pinned, fastened with adhesive, welded, or threaded to the low speed shaft608. In some embodiments, a low speed stator bearing610is used to align the input stator80arelative to the low speed shaft608. The low speed stator bearing610is preferably a radial bearing that fits into an inside diameter of the low speed shaft608and also over a flange or into the bore of the input stator80a.

Still referring toFIGS. 9 and 10, power is transferred from the bearing disc60to the perimeter ramps61, to the ramp bearings62, to the input disc34, to the balls1, to the idler18, and to the transfer shaft624. The idler18is rigidly attached to the transfer shaft624, which is a long cylindrical component that rotates about the longitudinal axis12. In some embodiments, the idler18is attached with an interference press fit, while in other embodiments it can be keyed, pinned, fastened with adhesive, welded, or threaded to the transfer shaft624. In still other embodiments, the idler18and the transfer shaft624are combined into one part. The transfer shaft624at a first end on the low speed side of the transmission600is inserted into the bore of the low speed shaft bearing604so that the transfer shaft624is able to slide axially. In some embodiments, the low speed shaft bearing604is eliminated and the transfer shaft624is shortened, terminating at the low speed side of the idler18. The transfer shaft624in some embodiments is made from the same material as the idler18and in other embodiments can be made from a tough steel, such as 4130, that is partially heat treated. In low torque applications the transfer shaft624can be made from aluminum, titanium, plastic, or any other suitable material. The transfer shaft624is further supported and located by a high speed shaft bearing605, which in some embodiments is a radial bearing inserted into the bore of the output stator80b, and over the outside diameter of the transfer shaft624, allowing the transfer shaft624to move axially. At a second end on the high speed side of the transmission600the transfer shaft has integrally formed into its surface one or more transfer grooves634.

Referring toFIGS. 11 and 12, in some embodiments four transfer grooves634are formed into the transfer shaft624, but in other embodiments 1, 2, 3, 5, 6, or more transfer grooves634can be used. Each transfer groove634is an indentation extending in a direction parallel with the longitudinal axis12and which has a concave radius profile. Fitted into each transfer groove634are one or more transfer bearings628. The transfer bearings628are typically hardened steel spheres common in the art, and the size and number of transfer bearings628can be adjusted to suit the power requirements of the application. Typically, the transfer grooves634will have a radius that is slightly larger than the radii of the transfer bearings628.

Still referring toFIGS. 11 and 12, a high speed shaft602contacts and is rotated by the transfer bearings628. Corresponding shaft grooves636, identical to the transfer grooves634except that they are formed on the inside diameter of the high speed shaft602rather than the outside diameter of the transfer shaft624, are positioned so that the transfer bearings628fit into and contact both the transfer grooves634and the shaft grooves636. Power is distributed among the transfer bearings628and is transferred from the transfer shaft624to the high speed shaft602. The high speed shaft602is a generally cylindrically shaped component that rotates about the longitudinal axis12. The inside diameter of the high speed shaft602is slightly larger than the outside diameter of the transfer shaft624. The high speed shaft602can be attached to a drive shaft, generator, sprocket, pulley, gear, wheel, or any other rotating device. The transfer grooves634and the shaft grooves636are longer than the axial space taken up by the transfer bearings628so that the transfer bearings628can roll axially when the transmission600is shifted. For some embodiments, the transfer bearings628will roll half the distance that the idler18and transfer shaft624move axially when the transmission600is shifted and thus the lengths of the transfer grooves634and the shaft grooves636can be calculated with the following equation:
x/2+d*y=length of transfer groove 634 and shaft groove 636

where x=the total axial distance the idler18can be shifted, d=the transfer bearing628diameter, and y=the number of transfer bearings628in each transfer groove634.

In some embodiments, the lengths of each transfer groove634and shaft groove636are increased slightly to provide a margin of error so that the transfer bearings628do not run out of space when they are rolling axially.

Referring toFIGS. 10,11,12,16, and17, shifting of the transmission600will be described. The output stator80bcomprises a stator tube658which extends through the wall of the case40(seen inFIG. 10). Outside of the case40, the stator tube658fits into the bore of the brace630. The brace630is a generally cylindrical component with a flange at a first end, and in some embodiments is made from steel. In other embodiments, the brace630can be made from aluminum, titanium, plastic, a composite, or any other suitable material. Holes positioned circumferentially around the flange provide for attachment of the brace630to a strong stationary structure (not shown), such as a frame or the case of a generator. Fasteners, such as bolts or machine screws are inserted through the flange holes on the brace630, and then through corresponding holes in the stationary structure to rigidly and securely attach the brace630.

At a second end of the brace630, additional holes which extend radially through the cylindrical portion of the brace630align with stator holes654in the stator tube658. The output stator80bfits inside of the bore of the brace630with a small amount of clearance although in some embodiments the brace630fits inside the bore of the output stator80b. The lever mounts640aand640bare rigid, L-shaped components incorporating a bend at a first end and attach to and provide a pivot for the levers622aand622b. Two lever mounts640a,640b, are used although 1, 3, 4, or more may be used. The lever mounts640a,640b, at a first end, the end with the bend, have holes which align with holes on the brace630. Brace fasteners632, which can be standard fasteners such as machine screws or bolts, are used to secure the lever mounts640a,640b, to the brace630and the output stator80b. In some embodiments, the holes in the lever mounts640a,640b, and the brace630are clearance holes, and the stator holes654are threaded. At a second end of the lever mount640, a single hole is provided to allow attachment of a lever622to the lever mount640. A corresponding hole in the lever622provides for mounting a lever pin642through the lever622to the lever mount640. Preferably, a small amount of clearance between the lever pin642and the hole in the lever622is provided so that the lever622may rotate freely about the pivot created by the lever pin642.

In some embodiments a second hole, located near a first end of the generally elongated, flat, bar shaped lever622, is provided so that an actuator pin644may be inserted through the second hole into an actuator638. Both the lever pin642and actuator pin644may be fastened with threads, an interference fit, or other suitable methods. An actuator638, a generally flat, straight, bar shaped component is attached to the actuator pin644near a first end. Near a second end the actuator638can be attached to a device (not shown) that controls shifting, such as a servo motor, cable, or actuator. Upon axial movement of the actuator638, the lever622pivots about the lever pin642. The mechanical advantage of the lever can be controlled by adjusting the distance between the lever pin642and the actuator pin644.

Referring toFIGS. 9,11,16, and17, in some embodiments the lever622near a second end is forked shaped with a slot formed into its second end. The slot surrounds and contacts a shift ring620, which in some embodiments is an annular ring with a profile of a radius at its outside diameter and a flat on its inside diameter. The mechanical advantage of the lever622can be adjusted by changing the distance between the shift ring620and the lever pin642. The shift ring620in some embodiments is made from hardened steel to resist wear, although in other embodiments different wear resistant materials such as plastic can be used. The inside diameter of the shift ring620is slightly larger than the outside diameter of the output stator80b, to allow axial sliding of the shift ring620over the stator tube658. Ring holes660are formed into the shift ring620to allow insertion of shift pins616a,616binto the shift ring620. In some embodiments, the shift pins616a,616bare hardened dowel pins which are pressed with an interference fit into the ring holes660. The shift pins616a,616bmay also be attached with adhesive or other methods common in the art. The shift pins616a,616bare inserted into the shift ring620after the shift ring620is assembled over the stator tube658and positioned so that the ring holes660are aligned with the stator slots656.

In some embodiments, there are two stator slots656although 1, 3, 4, or more be used. The stator slots656are elongated slots formed parallel with the longitudinal axis12and provide enough space so that the shift pins616a,616b, may slide freely in an axial direction within the stator slot656. The shift pins616a,616bextend through the stator slots656inside the stator tube658. Positioned on either side of and contacting the shift pins616a,616b, on a first side are the shift bearings614a,614b. The shift bearings614aand614bmay be annular bearings capable of absorbing thrust loads and are coaxial with the longitudinal axis12. On a second side, the shift bearing614acontacts the shaft flange609on the transfer shaft624. The shaft flange609is a disc shaped protrusion on the transfer shaft624and in some embodiments is formed integral to the transfer shaft624. On a second side, the shift bearing614bcontacts the shift lock618, an annular ring which in some embodiments is threaded onto the transfer shaft624until it contacts shift bearing614b. The shift lock618can be held in place with adhesive, or the threads may terminate slightly before the shift lock618contacts shift bearing,614b, and the shift lock618can be tightened against shift bearing614b. In other embodiments, the shift lock618is pressed over the transfer shaft624with an interference fit until it contacts shift bearing614a. When the actuators638a,638b, are moved axially toward the high speed shaft630, the transfer shaft624and idler18move axially toward the low speed shaft608, shifting the transmission to a higher speed. When the actuators638a,638b, are moved axially toward the low speed shaft608, the transfer shaft624and idler18move axially toward the high speed shaft630, shifting the transmission to a lower speed.

Referring now toFIGS. 9 and 10, the output disc101of the transmission600is rigidly attached to, and rotates with, the case40. In some embodiments, the output disc101can be formed as part of the case40. When the balls1are positioned so that their axes are parallel with the longitudinal axis12, the case40rotates at the same speed as the input disc34. At this ratio, there is no relative movement between the case40and the input disc34, and the bearing disc bearing66does not rotate. At this ratio, efficiency of the transmission600is maximized and it is recommended that in most applications the transmission600be designed so that the case40and the input disc34are rotating at the same speed at the speed ratio most frequently used.

Referring toFIG. 13, it shows the idler18and the shift guides13a,13b. Due to the fact that the transfer shaft624rotates, clearance between the bore of the shift guides13a,13b, and the transfer shaft624is preferred so that the components do not rub against each other. In some embodiments, a bearing race is formed into the shift guides13a,13b, and the idler18, to house the idler bearings17a,17b. In other embodiments, stock bearings may be used and it is not necessary to form a bearing race into the shift guides13a,13b, and the idler18.

Referring toFIG. 18, an alternative transmission1800is designed to decrease speed as well as vary speed. Compared to the transmission600, in the transmission1800the input and output are switched, otherwise the transmissions600and1800are similar. In a transmission1800designed to decrease speed, the high speed shaft602, is attached to input torque means, such as an electric motor, internal combustion engine, human powered machine, etc. Power follows the reverse direction of the transmission600and exits through the low speed shaft608. The input disc34of transmission600is no longer an input disc34, and becomes the low speed disc1834of transmission1800, but is otherwise similar to the input disc34.

Referring toFIGS. 14 and 15, the speed ratios of a speed increasing transmission600are explained. Near the top ofFIG. 14, an angle alpha of 45 degrees is shown. Alpha is the angle in degrees at which the input disc34and output disc101contact the balls1from their equators when the ball axles3are parallel to the longitudinal axis12. Near the center right ofFIG. 14, an angle gamma of 22 degrees is shown. Gamma is the angle in degrees at which the ball axles3are tilted relative to the longitudinal axis12, to produce variable speed and torque. The idler track650shows the circle diameter on the ball1where the idler18and ball1contact. It can be seen inFIG. 14that with a positive gamma of 22 degrees, the idler track650is larger than the input disc track652. A track generally refers to a path of frictional contact. InFIG. 15it can be seen that with a negative gamma of 22 degrees, the idler track650and the input disc track652are nearly equal, and when negative gamma is one half of alpha, the idler track650and the input disc track652are equal. When negative gamma equals one half alpha, the speed increase through the transmission600is equal to the input disc34radius divided by the idler18radius. For a speed decreasing transmission1800, the relationships shown inFIGS. 14 and 15are the same as for transmission600but the power direction is reversed.

Referring now toFIGS. 19 and 20, relationships among transmission100, transmission600, and transmission1800, are shown in two charts. In these charts, the top row provides variables from which speed ratios and relationships can be calculated. The first variable is alpha, and by comparingFIG. 19withFIG. 20, it can be seen that changing alpha from 50 to 35 degrees produces significant changes in the transmissions100,600, and1800. The row immediately underneath the top row gives the names of the variables calculated in each column. For example, the first cell in the second row is gamma, and the column underneath gamma lists various values for gamma. The second cell in the second row is Ball radius @ input, which is equal to one half the input disc track652. The third cell is Ball radius @ output, and the column underneath this cell provides this radius at different values for gamma. The fourth cell is Ball radius @ idler, which is equal to one half the idler track650. The fifth cell is Speed Increaser Ratio, which is the ratio produced by the transmission600. The sixth cell, Ratio range, gives the overall ratio for various values of gamma. The seventh cell, Average speed increase, provides the average speed increase at various gamma values. The eighth cell is termed Normal Mode Speed Ratio which gives the ratios for the transmission100. The ninth cell, Speed Reducer Ratio, gives the speed ratios for the transmission1800. The tenth cell, Ratio range, gives the overall ratio range for the transmission1800. The eleventh cell, Average Speed Decrease, gives the average speed decrease for the transmission1800.

It can be seen that in the column Speed Increaser Ratio, which is the ratio produced by the transmission600, speed does not change linearly with changes in gamma. For example, inFIG. 19, the change in speed from a gamma of −24 to −25 is 0.03, while the change in speed from 24 to 25 is 0.38, a rate of change over 12 times greater than 0.03. This produces a situation where larger changes in negative gamma are required to achieve the same speed and torque ratio change as positive gamma. Due to the fact that output speed is lower in gammas with negative values than in positive gammas, output torque is higher in gammas with negative values. Thus, at higher output torques the balls1and idler18move more than at lower output torques for equivalent ratio changes, which spreads wear over larger surface areas of the balls1and idler18.

Referring toFIGS. 10 and 18, the relationships of torque and speed through the transmissions600and1800are explained. In the transmission600, torque enters through the low speed shaft608, continuing through the bearing disc60, perimeter ramps61, and the ramp bearings62, before reaching the input disc34. An annular bearing race is formed on the input disc34, which helps locate the ramp bearings62. The ramp bearings62also serve an additional function of centering the input disc34. Due to the fact that in the transmission600speed is always higher at the high speed shaft602than the low speed shaft608, regardless of gamma, torque is always lower at the high speed shaft602than the low speed shaft608. Thus, maximum torque occurs on the low speed, or input side of the transmission600, and the optimal axial force to prevent slippage is determined by the highest torque produced in the transmission600. The torque sensitive perimeter ramps61are thus located in the optimum area of transmission600to produce the optimum axial force at all ratios, which is between the low speed shaft608and the balls1. This simple method to optimize axial force at all ratios and at all torques maximizes efficiency of the transmission600.

In the transmission1800, torque enters the high speed shaft602, travels a path through the transfer bearings628, transfer shaft624, idler18, balls1, low speed disc1834, ramp bearings62, perimeter ramps61, and bearing disc60, before reaching the low speed shaft608. Due to the fact that in the transmission1800speed is always lower at the low speed shaft608than the high speed shaft602, regardless of gamma, torque is always higher on the output side of the transmission1800, between the balls1and the low speed shaft608. Thus, the perimeter ramps62are ideally located on the output side of the transmission1800to optimize axial force at all ratios. This simple configuration maximizes efficiency of the transmission1800at all ratios and at all torques.

Referring toFIG. 21, an embodiment of the transmission600is shown implemented in a wind turbine670. Typically, in wind turbines the rotor688rotates at a speed slower than the generator682. The rotor is attached to a gearbox shaft676which rotates a speed increasing gearbox690. In some wind turbines, speed increases of over 50 times bridge the gap between rotor speed and the required generator682speed. For example, the wind turbine rotor688may rotate at 20 rpm while the generator requires a speed of 1200 rpm. For this configuration, the gearbox690may be adapted to increase speed 60 times. The gearbox690will typically increase speed in three stages, each stage increasing speed by a fixed ratio, generally between 3.5 and 6 times. There are variations to this range depending on the size of the wind turbine and the choice of generator682. Since usually the gearbox690is expensive, heavy, and prone to breakage, it is desirable to minimize the size, weight, cost, and number of stages in the gearbox690. Further, each stage of the gearbox690reduces efficiency, generally between 2-3%.

Still referring toFIG. 21, in some applications it is desirable to capture gusts of wind that produce torque spikes; however, these spikes can stress and ultimately damage the drivetrain of the wind turbine670. Typically, a wind turbine670will respond to gusts by pitching the blades of the rotor688and shedding wind; however, this cannot be done instantaneously. A variable speed transmission600that can be shifted quickly in response to a gust would allow the rotor688to increase speed, capturing the gust and minimize, or completely eliminate, the damage caused by torque spikes. Further, the transmission600has torque spike absorbing characteristics, which include the perimeter ramps61. The ramp bearings62will roll up the perimeter ramps61in response to an increase in torque, helping to absorb torque spikes.

Still referring toFIG. 21, it is desirable to vary speed of the rotor688as wind speeds change. This allows the rotor688to rotate at its aerodynamic optimum, maximizing the energy that can be extracted from the wind turbine670. Generally, a variable speed wind turbine670will produce 10% more energy than a fixed speed wind turbine. However, the generator682requires a near constant speed. Currently, power electronics are used to create variable speed in a wind turbine.

Embodiments of the transmission600can be shifted so as to capture gusts and minimize damaging torque spikes, can increase speed and replace at least one stage of the gearbox690, and can vary speed as wind speeds change, thus holding a constant speed into the generator682.

Still referring toFIG. 21, a drivetrain for a wind turbine670that implements the transmission600is described. The gearbox690is rigidly attached to the nacelle680with the gearbox mount678, a strong rigid structure designed to absorb the very large torques that are produced by a wind turbine670drivetrain. The nacelle680is a large stationary case which houses and protects the gearbox690, transmission600, generator682, and other wind turbine components from the weather. On the output side of the gearbox690, a shaft is connected to the low speed shaft608of the transmission600. Speed is increased as well as varied through the transmission600, which is located inside the nacelle680, and between the gearbox690and the generator682. Depending on wind speed and thus the rotor688speed, the transmission600will increase or decrease speed into the generator682. If the rotor688speed is high due to strong winds, the transmission600will shift to a lower speed. If the rotor688speed is slow due to low wind speeds, the transmission600will shift to a higher speed.

Referring now toFIG. 22, a textured surface701profile of the balls1, the input disc34, the low speed disc1834, the output disc101, and the idler18, is shown for the transmissions100,600, and1800. The textured surface701in some embodiments are of a shape that resist wear and preferably do not have any sharp corners or features prone to removal or deformation. In some embodiments, the textured surface701produces microscopic domes from 1-10 microns on the surfaces of the above components, depending on the speed, size, and torque rating of the transmissions100,600,1800. The textured surface701can be formed into the balls1, input disc34, low speed disc1834, output disc101, and idler18by tumbling, shot peening, sandblasting, laser etching, or any other suitable method. If the components are made from molded plastic, in addition to the above techniques, the mold surfaces or cavities can be varied to produce the textured surface701. The textured surface701increases friction between the surfaces of the balls1and the input disc34, the low speed disc1834, the output disc101, and the idler18. This reduces the amount of axial force, or clamp force required to transfer torque without slippage of these components in the transmissions100,600,1800. The textured surface701significantly increase the surface area of the balls1, input disc34, low speed disc1834, output disc101, and the idler18, aiding heat dissipation.

Still referring toFIG. 22, in some embodiments, a hard, wear resistant coating702is applied to the surfaces of the balls1, the input disc34, the low speed disc1834, the output disc101, and the idler18. The coating702in some embodiments is hard, wear resistant, resilient, high friction, and bonds well to steel, such as silicon nitride. A silicon nitride coating702can be between 0.5 to 5 microns thick, depending on the size, speed, and torque rating of the transmissions100,600, and1800. Two suitable methods to apply a silicon nitride coating to steel are plasma vapor deposition and chemical vapor deposition. The high temperatures required for some chemical vapor deposition processes make it unsuitable for some hardened steels such as 52100 and some other bearing steels because these steels will lose their temper during the coating process. In transmission100,600,1800applications where the excellent bond produced from chemical vapor deposition is required, the use of tool steel for the balls1, the input disc34, the low speed disc1834, the output disc101, and the idler18, may be required. The increased surface area produced by the textured surface701increases the amount of the coating702that can be applied to the surfaces. The bumpiness produced by the textured surface701increases the strength of the mechanical bond between the surface of the textured surface701and the coating702.

The embodiments described herein are examples provided to meet the descriptive requirements of the law and to illustrate various ways to practice the mechanisms, methods of use, methods of manufacturing, etc., of the present invention. The embodiments described here explain and facilitate the full comprehension and enablement of all that is disclosed here. The description of these examples is not intended to be limiting in any manner. Additionally, here terms are used in their broad respective senses unless otherwise stated. Therefore, terms should not be read as being used in any restrictive sense or as being redefined unless expressly stated as such.