SYSTEMS AND METHODS FOR FLUID CIRCULATION AND DELIVERY IN CONTINUOUSLY VARIABLE TRANSMISSIONS

Abstract

A lubrication system for fluid circulation and delivery to specific components in ball planetary continuously variable transmissions contained in spinning hubs. A tube has a first end extending radially outward into a fluid volume maintained by inertia caused by the spinning shell and a second end extends radially inward near a component. An orifice is positioned near an interior surface of the hub shell and an opening is positioned near the component, such as a sun bearing, planet axle, or other rotating component. As the shell rotates, fluid rotating with the shell enters the orifice and is forced along the tube to the opening, where it exits to lubricate the selected component or components. A circumferential groove in the hub shell collects fluid for controlling fluid flow into the tube, reducing the volume of fluid needed in the CVT.

Claims

1. A ball planetary continuously variable transmission (CVP) having a rotatable hub shell containing a plurality of spherical planets arranged around a main axle defining a longitudinal axis of rotation, each spherical planet having a planet axle defining a planet axis of rotation, wherein tilting the planet axes of rotation changes a speed ratio of the CVP, the rotatable hub shell configured to retain a lubrication fluid, the CVP comprising a lubrication system, the lubrication system comprising: a lubrication tube configured to supply lubrication to components radially inward of the lubrication tube, the lubrication tube comprising: a first end extending radially outward; an orifice at the first end; a second end extending radially inward; and an opening at the second end, wherein rotation of the hub shell causes the lubrication fluid to enter the orifice, flow along the tube, and exit the opening.

2. The CVP of claim 1, wherein the hub shell comprises an interior surface, and wherein the first end of the tube extends to a location radially outward of the longitudinal axis and proximate to the interior surface.

3. The CVP of claim 2, wherein the interior surface of the hub shell comprises a smooth surface.

4. The CVP of claim 2, wherein the interior surface of the hub shell comprises a feature for controlling fluid flow of the lubrication fluid.

5. The CVP of claim 2, wherein an exterior surface of a cross-section of the orifice is complementary to a profile of the interior surface.

6. The CVP of claim 1, wherein an exterior surface of a cross-section of the orifice is one of circular, tear drop, angled, or asymmetric.

7. The CVP of claim 4, wherein the feature for controlling fluid flow comprises a circumferential groove, and wherein lubrication fluid is configured to flow into the circumferential groove.

8. The CVP of claim 7, wherein an exterior surface of a cross-section of the orifice is complementary to the circumferential groove.

9. The CVP of claim 1, wherein the opening and a component of the CVP are located at a same location radially outward of the longitudinal axis and proximate to the interior surface.

10. The CVP of claim 9, wherein the component of the CVP comprises a spherical planet.

11. The CVP of claim 1, wherein an outer surface of the tube is configured for contact with the lubrication fluid, whereby lubrication fluid flows radially inward along the outer surface of the tube.

12. The CVP of claim 1, wherein the tube is fixed to a non-rotatable component of the CVP.

13. The CVP of claim 1, wherein the tube is coupled to a carrier of the CVP.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0062] The accompanying figures, which are incorporated in and form a part of the specification, illustrate certain features of the inventive embodiments.

[0063] FIGS. 1-20 depict schematic diagrams of configurations of drivetrains having a continuously variable transmission forming a part thereof;

[0064] FIGS. 21-24 depict schematic diagrams of CVPs, illustrating U-drive and through drive embodiments of CVPs; and

[0065] FIGS. 25A-25C depict partial cut-away views of a portion of a CVP, illustrating one embodiment of a lubrication system.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

[0066] Embodiments of the present disclosure will now be described with reference to the accompanying figures, wherein like numerals refer to like elements throughout. The terminology used in the description presented herein is not intended to be interpreted in any limited or restrictive manner simply because it is being utilized in conjunction with a detailed description of certain specific embodiments of the present disclosure. Furthermore, embodiments of the present disclosure may include several novel features, no single one of which is solely responsible for its desirable attributes or which is essential to practicing the present disclosure herein described.

[0067] Embodiments disclosed herein relate generally to continuously variable transmissions (CVTs), including infinitely variable transmissions (IVTs). More particularly, embodiments relate to CVTs and their components, as well as subassemblies and systems which may take advantage of the features, available power paths, and configurations possible with a CVT. Embodiments may also relate to vehicles, equipment, machinery, and other applications which may incorporate the functionality of a CVT to improve the performance or efficiency of existing and known technologies.

[0068] For embodiments disclosed with respect to the figures, the following descriptions may be helpful.

[0069] As used here, the terms coupled, operationally connected, operationally coupled, operationally linked, operably connected, operably coupled, operably linked, and like terms, refer to a relationship (mechanical, linkage, coupling, etc.) between elements whereby operation of one element results in a corresponding, following, or simultaneous operation or actuation of a second element. It is noted that in using these terms to describe certain embodiments of the present disclosure, specific structures or mechanisms that link or couple the elements are typically described. However, unless otherwise specifically stated, when one of these terms is used, the terms indicate that the actual linkage or coupling may take a variety of forms, which in certain instances will be obvious to a person of ordinary skill in the technology. For description purposes, the term radial is used here to indicate a direction or position that is perpendicular relative to a longitudinal axis of a transmission or continuous variator. The term axial as used here refers to a direction or position along an axis that is parallel to a main or longitudinal axis of a transmission or continuous variator.

[0070] Unless otherwise explicitly stated, as used herein, the term or refers to an inclusive statement. In other words, the statement A or B is true if any of the following conditions are met: A is True and B is False; A is False and B is True; or A is True and B is True.

[0071] Certain embodiments of the present disclosure described below incorporate spherical-type variators that use spherical speed adjusters, each of which typically has a tiltable axis of rotation. The speed adjusters are also known as power adjusters, balls, planets, spheres, sphere gears, or rollers. Usually, the adjusters are arrayed radially in a plane perpendicular to a longitudinal axis of a CVT. Traction rings are positioned on each side of the array of planets, with each traction ring being in contact with the planets. Either of the traction rings may apply a clamping contact force to the planets for transmission of torque from a traction ring, through the planets, to the other traction ring. A first traction ring applies input torque at an input rotational speed to the planets. As the planets rotate about their own axes, the planets transmit the torque to a second traction ring at an output rotational speed. The ratio of input rotational speed to output rotational speed (speed ratio) is a function of the ratio of the radii of the contact points of the first and second traction rings, respectively, to the rotational axes of the planets. Tilting the axes of the planets with respect to the axis of the CVT adjusts the speed ratio.

[0072] FIGS. 21-24 depict schematic diagrams of ball-planetary continuously variable transmissions (CVP's), illustrating configurations in which a CVP may be used as a U-drive or a through-drive transmission according to the present disclosure. Power may enter any of CVPs 2100, 2200, 2300, or 2400 via input sprocket 1 and be transferred through first traction ring 4A, planets 5, out second traction ring 4B to output sprocket 3. Sun 2 may be positioned radially inward of planets 5. Carrier 6 may be used to adjust a tilt angle of planets 5. Seals 8 may ensure a traction fluid is maintained within a CVP. Actuator 9 may control carrier 6 or otherwise tilt planets 5 to provide a target speed ratio.

[0073] As depicted in FIGS. 21 and 22, CVP 2100 and 2200 may function as a through-drive (i.e., input sprocket 1 and output sprocket 3 are located on opposite sides of planets 5).

[0074] As depicted in FIGS. 23 and 24, CVP 2300 and 2400 may function as a U-drive (i.e., input sprocket 1 and output sprocket 3 are located on the same side of planets 5).

[0075] One aspect of the torque/speed regulating devices disclosed here relates to drive systems for industrial vehicles which may operate at various speeds and require varying amounts of torque. A motorcycle is one example of a vehicle that might move at varying speeds and torques, depending on the terrain, the weight of the rider, and other factors. A prime mover in a motorcycle can be, for example, an electrical motor and/or an internal combustion engine. A motorcycle may also run other devices off the motor, including an alternator and a pump. Usually, the speed of a prime mover varies as the speed or power requirements change. The alternator or pump may operate optimally at another speed.

[0076] In the configurations presented herein, a ball-planetary type continuously variable transmission may be enclosed in a hub shell. In some embodiments, a CVP is enclosed in a hub shell that is rotatable (also referred to as a spinning hub shell). Ball-planetary type continuously variable transmissions (CVPs) can experience windage due to the presence of traction fluid around the planets. The effects of windage vary according to the type of traction fluid and the volume of traction fluid, as well as the geometry of the CVT. Loss of efficiency and reduced power capacity are significant concerns, but so are foaming, excessive turbulence, CVT damage, decreased service life and fluid damage are some examples of effects that may be the result of excessive windage.

[0077] In some embodiments, air cooling may be sufficient to cool all components in a scooter or motorcycle. In other embodiments, due to the size of the prime mover or other component, the position or orientation of any one component, the arrangement or configuration of any group of components, or the aerodynamic shielding or routing of air flow by a component or group of components, air cooling might be insufficient and additional cooling techniques may be necessary or target. A lubrication system may circulate lubricant adapted to coat and/or cool various components of a drivetrain. Embodiments disclosed herein include a lubrication system capable of supplying lubrication to key components while reducing the effects of windage.

[0078] FIG. 25A depicts a cutaway view of one embodiment of a ball planetary continuously variable transmission (CVP) having a spinning hub shell 2535, with traction fluid circulating and in contact with inner surface 2540 of hub shell 2535. In some embodiments, traction fluid may circulate between inner surface 2540 of hub shell 2535 and radially outward of traction rings 4A, 4B, outer surface 2580 of carrier 8A, 8B, radially outward of spherical planets 5, or some other component, depending on target operating parameters of CVP 2500.

[0079] FIGS. 25B-25C depict partial cutaway views of a portion of one embodiment of a continuously variable transmission, illustrating an exemplary lubrication system and a fluid circulation pattern relative to components in a spinning hub shell.

[0080] As hub shell 2535 of CVP 2500 rotates, fluid generally migrates radially outward in hub shell 2535 and circulates toward interior surface 2540 due to centrifugal action. Fluid in contact with interior surface 2540 will start circulating in the same direction that hub shell 2535 rotates. The velocity at which fluid flows depends on surface features and other characteristics of interior surface 2540, surface friction between interior surface 2540 and molecules of the fluid, viscosity and other characteristics of the fluid, and other characteristics of the CVT. In some embodiments, interior surface 2540 is a continuous surface, whereby surface friction between interior surface 2540 and the fluid is the predominant mechanism by which fluid flows. In other embodiments, interior surface is discontinuous, and grooves (transverse or longitudinal), dimples or other recessed or protruding features may push fluid or otherwise generate fluid flow forces to cause fluid to flow, or may increase a surface area of interior surface 2540 or otherwise adhere the fluid to interior surface 2540, thereby increasing the volume of fluid available for use in a speed-based lubrication system.

[0081] FIGS. 25B-25C further depict partial cutaway side views of embodiments of a speed-based lubrication system. As depicted in FIGS. 25B-25C, a speed-based lubrication system may include tube 2550 positioned in CVP 2500 with orifice 2555 extending radially outward into fluid that is centrifugally held out at interior surface 2540 and openings 2560A, 2560B located radially inward to direct the fluid to a sun pilot bearing or other components of CVP 2500. In some embodiments, tube 2550 may include middle portion 2552 having one or more curves, angles, orifices, nozzles or other fluid dynamics feature. The size or shape of any fluid dynamics feature may ensure a flow rate of a lubrication fluid exiting openings 2560A, 2560B is at least a minimum flow rate, less than a maximum flow rate, or within some range of flow rates, or may ensure a fluid pressure of a lubrication fluid exiting openings 2560A, 2560B is at least a minimum fluid pressure, less than a maximum fluid pressure, or within some range of fluid pressures.

[0082] Orifice 2555 is ideally situated near interior surface 2540 such that tube 2550 interacts with fluid. As the fluid interacts with tube 2550, a volume of the fluid will enter orifice 2555 of tube 2550 near interior surface 2540 of hub shell 2535 and flow through tube 2550 to one or more openings 2560 located radially inward. The viscosity and other characteristics of the fluid, the rotational velocity of the shell, and the orifice and tube internal characteristics determine the pressure and rate at which fluid flows through tube 2550 to openings 2560. Openings 2560 are arranged and configured to provide a flow rate of fluid at a target pressure to be delivered to one or more components. In some embodiments, orifice 2555 may be configured to provide an input flow rate and pressure and two or more openings 2560A, 2560B may allow equal or controlled flow rates and pressures of traction fluid.

[0083] The fluid volume may be selected so that the planets are partially submerged in a fluid region. The level to which the planets are submerged may be based on maximizing fluid delivered to a component (such as a sun, ring, or other component of CVP 2500), maximizing fluid passing through an orifice, minimizing windage, or some other performance characteristic.

[0084] Fluid in contact with the planets will adhere to the planets until the spin reaches a speed to cast or sling the fluid outward and radially towards the drive center (sun assembly).

[0085] As depicted in FIGS. 25A-25C, tube 2550 in a lubrication system may receive fluid from a fluid volume circulating radially outward in hub shell 2535 (such as fluid that is centrifugally held out at hub shell 2535 interior surface 2540) and direct the fluid to a target area or component within CVP 2500. Fluid may be received via orifice 2555 oriented circumferentially, may circulate in tube 2550 radially inward due to fluid pressure applied by the fluid at orifice 2555, and may exit tube 2550 axially through one or more openings 2560A, 2560B. The positioning and/or orientation of openings 2560 2560A, 2560B may be to provide fluid to a particular region or component. In some embodiments, at least one opening 2560 is positioned, shaped or configured to provide fluid to a sun pilot bearing associated with sun 2.

[0086] At slower speeds, fluid may flow along outer surface 2570 of tube 2550. However, once the rotational speed of hub shell 2535 exceeds a threshold, the effectiveness of using outer surface 2570 for fluid flow may decrease. At these higher speeds, inertia of the fluid may force fluid into orifice 2555 and through tube 2550 to opening 25602560A, 2560B. Tube 2550 may have curves 2552 for directing fluid flow. At slower speeds, fluid may flow along outer surface 2570 of tube 2550 until the fluid reaches curve 2552. At curve 2552, fluid may separate from outer surface 2570.

[0087] In some embodiments, orifice 2555 is manufactured with a circular cross section area to be perpendicular to a fluid flow profile of the fluid to maximize flow rate per inlet area. However, in some embodiments orifice 2555 may be manufactured to be angled with respect to the fluid flow profile. Having an asymmetric inlet area or having an angled orifice may be useful for reducing negative effects of windage or ensuring a target flow rate or fluid pressure of lubrication fluid.

[0088] In some embodiments, a trough or other circumferential fluid channel is provided in hub shell 2535 to reduce the effects of windage on traction planets while still providing sufficient fluid for cooling. Positioning orifice 2555 of tube 2550 in a trough may allow orifice 2555 to be made smaller without the associated drag coefficient. In some embodiments, if orifice 2555 is positioned in a trough, orifice 2555 may be manufactured with a tear drop, angled, triangular, or other cross section area complementary to a cross section area of the trough.

[0089] In some embodiments, the oil volume held at interior surface 2540 may be used to act upon a movable carrier to assist with adjusting a speed ratio of CVP 2500. In general, a circulation direction and which carrier 8A, 8B is allowed to tilt planets 5 tends to add torque towards underdrive (UD). Embodiments disclosed herein may include a set of vanes or other features configured to provide direction circulation and formed as part of a fixed carrier that would redirect the fluid in the opposite direction upon a movable carrier to help create torque towards over drive (OD).

[0090] In some embodiments, cantilevered links are rotatably pinned to a fixed carrier. One end of the link extends radially outward into fluid retained against interior surface 2540 by inertia (which may be referred to as centrifugal action), and the other end of the link extends radially inward and contacts a movable carrier (such as carrier 8A, 8B in FIGS. 21-25C). The shape of the link causes the link to retract or fold out of the fluid stream when a CVP is operating in underdrive (UD) and extend out into stream when the CVP is operating in overdrive (OD). As hub shell 2535 rotates, fluid circulating inside hub shell 2535 contacts a radially outward end of a link causing the link to rotate about its axis. Rotation of the link about its axis causes a radially inward end of the link to contact a movable carrier, biasing the movable carrier toward either underdrive (UD) or overdrive (OD). In one embodiment, the movable carrier is biased toward overdrive.

[0091] The embodiments described herein are examples provided to, among other things, meet legal requirements. These examples are only embodiments that may be used and are not intended to be limiting in any manner. Therefore, the claims that follow, rather than the examples, define the present disclosure.