Patent Application
20180363763
As emission limits place greater emphasis on optimizing drivetrain performance in vehicles, motorcycles and other lightweight vehicles are becoming more popular. Their popularity is due in part to small motors and engines generating more power with increased efficiency. Both internal combustion engines and electric motors are advancing in technology such that smaller engines and electric motors are capable of even greater power and efficiency, making these lightweight vehicles even more popular.
Most motorcycle drivetrains have an engine as a prime mover, but electric motors are also gaining popularity as manufacturers look to new power options.
In addition to an engine or motor, motorcycles generally include a gear box having a few gears, a clutch to switch between gears, and either a chain-sprocket system or belt-pulley system that transfers power from the engine to the rear wheel while providing a fixed gear ratio. Recently, manufacturers have started implemented belt driven continuously variable transmissions (CVTs) for possible improvements in the overall performance of the drivetrain.
In power generation systems such as internal combustion engines, torsional vibration is commonly generated relative to a shaft along its axis of rotation. Torsional vibration can cause failures if not controlled, and torsional vibration can lead to noticeable vibrations or noise at certain speeds, which are undesirable. A torsion damper (also referred to as a torsional damper, torsion dampener or torsional dampener) is included to reduce torsional vibration in a drivetrain.
An engine may operate optimally at a first speed (N1), but a pump, alternator, or other component may operate optimally at a lower speed (N2), and a wheel may rotate at a third speed (N3). A gear ratio (GR) between the prime mover and a component allows the prime mover to operate within a first speed range and the component to operate within a second speed range.
A transmission with multiple gears has multiple gear ratios and allows the engine or motor to operate within a first speed range and the vehicle to travel at a target speed. A gear ratio may be implemented by various systems, including two gears or pulleys with a chain, belt, or other endless member, or a gear set, such as a planetary gear set. Typically, motorcycles have a front gear (with a first radius and first tooth count) associated with an output of the engine coupled by a chain or belt to a rear gear (with a second radius and second tooth count) associated with the rear axle. The difference between the first radius and the second radius results in a speed reduction (and a corresponding torque increase).
As used herein, the term “transverse” or “longitudinal”, when referring to prime mover orientation, generally refers to an orientation of a crankshaft in an internal combustion engine or an orientation of an output shaft for an electric motor. A “transverse crankshaft engine” refers to an engine in which the crankshaft is perpendicular to a plane that divides the vehicle frame into left and right halves. A “longitudinal crankshaft engine” refers to an engine in which the crankshaft is contained in or parallel to a plane that divides the vehicle frame into left and right halves. A “transverse shaft motor” refers to a motor in which the output shaft is perpendicular to a plane that divides the vehicle frame into left and right halves. A “longitudinal shaft motor” refers to a motor in which the output shaft is contained in or parallel to a plane that divides the vehicle frame into left and right halves. A transverse orientation may also be referred to as an “east-west” or “left-right” orientation and a longitudinal orientation may also be referred to as a “north-south” or “front-rear” orientation.
A prime mover may be an engine such as an internal combustion engine (“IC engine” or “ICE”) or an electric motor. Control of a prime mover may be accomplished via signals from a control system. A control system may receive input from a human operator and convert that input into an output signal corresponding to a target power requirement for a drivetrain.
Internal combustion engine firing pulses may introduce torsional vibration in a drivetrain. A torsional damper may reduce vibrations to reduce rattle and premature wear on components or otherwise extend the life of a drivetrain. Various dampers may be used without affecting the operation of a CVT or the drivetrain. For example, a torsional damper with a long travel or otherwise torsionally soft dampening may be included, particularly for single cylinder engines. As the number of cylinders increases, torsional vibration may be managed in other ways.
Continuously variable transmissions (CVTs) may include continuously variable planetary transmissions (CVPs). A CVP traction drive is stiffer than a belt-pulley CVT, and torsional stiffness and characteristic inertia of a CVP may vary relative to ratio. In some configurations, a CVP may function as a U-drive, allowing power from a prime mover on a first side to pass through the CVP (via, for example, a shaft extending through a CVP) and exit the CVP on the same side as the prime mover. In other configurations, power from a prime mover may enter on one side of a CVP and exit the CVP on an opposite side.
Clutches may be used to selectively engage or disengage from a main shaft passing from a prime mover. Centrifugal clutches—which use centrifugal force to engage concentric shafts—are commonly used in scooters, mopeds, motorcycles, and other vehicles, to disengage the drivetrain and to prevent an internal combustion engine from stalling during braking.
Gear sets may change a speed or torque in a drive train. If a gear set uses a belt or chain, a first pulley or sprocket with a first gear radius is coupled by a chain (or belt or endless member) to a second pulley or sprocket with a second gear radius. If a gear set is a planetary gear set, by selectively locking or unlocking one or more of a sun gear, a set of planet gears, or a ring gear, a drive train can operate in low mode, high mode, forward mode, or reverse mode. In some configurations, power may be input through the sun gear, and if the ring gear is locked, power exits the set of planet gears, but in a reverse direction. Other gear sets are possible.
During operation of a drivetrain, a prime mover generates and delivers power at certain torque and speed levels, which depend on, among other things, various load requirements. A control system receives signals indicating operating conditions for one or more of the prime mover and CVP and sends control signals to one or more of the prime mover, clutch, CVP, and possibly a gear set, gear box or other mechanisms for providing a gear ratio (GR). The control signals sent to one or more of the prime mover, clutch, gear set, and CVP ensure a target performance of the drivetrain.
To illustrate the advantages and characteristics of drivetrains incorporating CVTs (especially CVPs), various motorcycle drivetrain architectures are described. Those skilled in the art will appreciate after reviewing this disclosure that the exemplary concepts described herein may be useful for other vehicles having two or more wheels.
A drivetrain (such as in a motorcycle or scooter) may have components disposed on both sides relative to a lateral center of mass and at least partially in a longitudinal plane of the vehicle. For example,
Power exits torsion damper 20, crosses the longitudinal plane (to a “left hand” or “left” side), and changes from a transverse path to a longitudinal path via bevel gears 42A and 42B (collectively referred to as bevel gears 42-1), and enters CVP 30. Bevel gears 42-1 interposed between torsion damper 20 and CVP 30 may change power transmission from transverse to longitudinal and may further have a second gear ratio GR2 associated with gears 42A and 42B. In some configurations, GR2 is 1:1 indicating bevel gear 42-1 only changes the power transmission from transverse to longitudinal. In other configurations, GR2 is some other ratio, indicating bevel gear 42-1 may change the direction of power transmission and change a speed ratio.
Power enters CVP 30, where a tilt or other change adjusts a ratio of output speed relative to input speed. CVP 30 may be adjusted to a target speed ratio independent of the power generated by prime mover 10 or may be adjusted to a target speed ratio based on power generated by prime mover 10.
One of coupling 54 or 55 is engaged or disengaged by clutch 40, such that power exiting CVP 30 is allowed or prevented from reaching bevel gear 42-2 coupled to axle 56, which is coupled to wheel 50. Bevel gear 42-2 coupled to rear axle 56 may change power transmission from longitudinal to transverse and may further have a third gear ratio GR3. In some configurations, GR3 is 1:1 indicating bevel gear 42-2 only changes the power transmission from longitudinal to transverse. In other configurations, GR3 is some other ratio, indicating bevel gear 42-2 coupled to axle 56 may change the direction of power transmission and change a speed ratio.
In operation, control unit 80 may send signals to prime mover 10 to generate power, which will have an associated torque and speed. The generated power is transmitted via coupling 51 through gear set 60 having first gear ratio GR1, through torsion damper 20 to bevel gear 42-1 having second gear ratio GR2, and through coupling 52 to CVP 30. Power exiting CVP 30 is transmitted via coupling 54, through clutch 40 and coupling 55 to bevel gear 42-2 coupled to coupling 56, with bevel gear 42-2 coupled to coupling 56 having a third gear ratio GR3. Control unit 80 controls CVP 30 such that power exiting CVP 30 rotates wheel 50 at a target rate (revolutions per minute).
Some configurations of a drivetrain may have components located on one side of a longitudinal plane of the drivetrain or balanced relative to a longitudinal plane of the vehicle. An advantage to having all components on the same side of the longitudinal plane, in series (and possibly even coaxial) may include manufacturability, compactness of the drivetrain and maintenance.
Power enters CVP 30, where a tilt or other change adjusts a ratio of output speed relative to input speed. CVP 30 may be adjusted to a target speed ratio independent of the power generated by prime mover 10 or may be adjusted to a target speed ratio based on power generated by prime mover 10.
Power may exit CVP 30 via coupling 63 and enter gears 70, and exit gears 70 via coupling 64 to clutch 40. Coupling 64 may be engaged or disengaged from wheel 50 by clutch 40, such that power exiting gear box 70 is controlled by clutch 40. Control unit 80 may be communicatively coupled to one or more of prime mover 10, gear box 75 having multiple gear ratios (GRs), CVP 30, clutch 40, and gear 70 having a gear ratio (GR) or multiple gear ratios (GRs) and may receive sensor signals from any of a plurality of sensors associated with components on the vehicle or environmental conditions. For example, control unit 80 is configurable to control CVP 30 independently of a speed of a motorcycle, yet a speed sensor capable of determining motorcycle speed may be received by control unit 80 in some configurations. Furthermore,
In operation, control unit 80 may send signals to prime mover 10 to generate power, which will have an associated torque and speed. The generated power is transmitted via coupling 51 through torsion damper 20 through coupling 61 to gear box 75 having multiple gear ratios (GRs). Power from gear box 75 is transmitted via coupling 62 to CVP 30. CVP 30 may be adjusted for a target output torque or speed. Power from CVP 30 may be transmitted via coupling 63 to gear 70 having a gear ratio (GR) or multiple gear ratios (GRs), and from gear 70 via coupling 64 to wheel 50 depending on an engagement state of clutch 40.
A drivetrain may have some components located forward of the drivetrain and other components located at the back of the drivetrain. For example,
Control unit 80 may be communicatively coupled to one or more of prime mover 10, CVP 30, clutch 40, and gear box 75 having multiple gear ratios (GRs) and may receive sensor signals from any of a plurality of sensors associated with components on the vehicle or environmental conditions. For example, control unit 80 is configurable to control CVP 30 independently of a speed of a motorcycle, yet a speed sensor capable of determining motorcycle speed may be received by control unit 80 in some configurations. Furthermore,
A drivetrain may have components located primarily on a forward side of a frame hinge and at least partially in a plane of the vehicle that divides the vehicle into left hand and right-hand sides.
In operation, control unit 80 may send signals to prime mover 10 to generate power, which will have an associated torque and speed. The generated power is transmitted via coupling 51 to torsion damper 20, through coupling 52 to CVP 30, through coupling 54 to clutch 40, through bevel gear 42 having a first gear ratio (GR) and gear-chain set 60 having a second gear ratio (GR) to wheel 50. Control unit 80 may be communicatively coupled to one or more of prime mover 10, torsion damper 20, CVP 30, and clutch 40, and may receive sensor signals from any of a plurality of sensors associated with components on the vehicle or environmental conditions. For example, control unit 80 is configurable to control CVP 30 independent of a speed of a motorcycle, yet a speed sensor capable of determining motorcycle speed may be received by control unit 80 in some configurations. Furthermore,
A drivetrain may have components located primarily on a forward side of a frame hinge but not restricted to a plane of the vehicle.
Furthermore,
In operation, control unit 80 may send signals to prime mover 10 to generate power, which will have an associated torque and speed. The generated power is transmitted via coupling 51 through gear-chain set 60A having a gear ratio (GR), through torsion damper 20, through coupling 52 to CVP 30. Power from CVP 30 transmitted via coupling 54 to clutch 40, through coupling 57, gear-chain set 60B having a gear ratio (GR) and shaft 65 to wheel 50.
A drivetrain may have components disposed on a forward side of a frame hinge and oriented transversely.
In operation, control unit 80 may send signals to prime mover 10 to generate power, which will have an associated torque and speed. The generated power is transmitted via coupling 51 to torsion damper 20, through coupling 61 to gear box 70 having a gear ratio (GR) or multiple gear ratios (GRs), through coupling 62 to CVP 30, to clutch 40. Drive train 600 may be located forward, coplanar (including coaxial) with, or rear of a frame hinge.
A drivetrain may have components disposed on two axes in the vehicle.
Control unit 80 may be communicatively coupled to one or more of prime mover 10, CVP 30, clutch 40, and gear box 75, and may receive sensor signals from any of a plurality of sensors associated with components on the vehicle or environmental conditions. For example, control unit 80 is configurable to control CVP 30 independently of a speed of a motorcycle, yet a speed sensor capable of determining motorcycle speed may be received by control unit 80 in some configurations. Furthermore,
In operation, control unit 80 may send signals to prime mover 10 to generate power, which will have an associated torque and speed. The generated power is transmitted via shaft 71 to clutch 40, through shaft 72 and gear-chain set 60 having an associated gear ratio GR1 to gear box 75, through shaft 65 to CVP 30 in wheel 50.
A drivetrain may have selected components disposed on an axis between a prime mover axis and a wheel axis.
Control unit 80 may be communicatively coupled to one or more of prime mover 10, torsion damper 20, CVP 30, clutch 40, and gear box 75, and may receive sensor signals from any of a plurality of sensors associated with components on the vehicle or environmental conditions. For example, control unit 80 is configurable to control CVP 30 independently of a speed of a motorcycle, yet a speed sensor capable of determining motorcycle speed may be received by control unit 80 in some configurations. Furthermore,
In operation, control unit 80 may send signals to prime mover 10 to generate power, which will have an associated torque and speed. The generated power is transmitted via coupling 51 through gear-chain set 60A (including torsion damper 20), to gear box 75, through coupling 62 to CVP 30. Power from CVP 30 is transmitted via coupling 54 to clutch 40 and from clutch 40 through bevel gears 42-1 and 42-2 (two sets) and shaft 65 to wheel 50. Gear box 75 may be configured for a target output torque or speed. For example, power may enter a planetary gear set via an outer ring, may exit via a sun gear. Alternatively, a planetary gear set may be configured to allow power to enter via a carrier, a sun gear, a planet gear or some combination.
Similarly,
There exists a continuing need for CVTs, both as independent systems and as subassemblies integrated with existing technologies, in a multitude of powered applications.
In some systems, it would be beneficial to operate an electric motor or an internal combustion engine at an optimal speed and have a power modulating device manage vehicle speed for optimal acceleration, efficiency or range.
Embodiments disclosed herein may be based on any of the foregoing examples in accordance with OEM (Original Equipment Manufacturer) requirements for new design options for market differentiation. A configuration may be desirable to an OEM based solely on the ability for the OEM to market the configuration as unique. For example, a configuration may allow for a new design not previously available, or may allow for target functionality, such as a step through frame. A profile may be smoother for better aerodynamics or laterally extended for improved cooling of components. Components may be combined or positioned behind fairings for a more streamlined appearance. Components may be positioned based on one or more factors such as cooling (including positioning hotter components farther from a rider), noise reduction or abatement, ease of manufacturing, assembly, testing or maintenance, ability to have a sealed drivetrain or portion thereof to avoid ingress of dirt, water or cooling fluids, or allow for jack points or other serviceability requirements or desires. In some embodiments and configurations, off-the-shelf (existing), lighter, or smaller components may be desirable to reduce the overall weight of the motorcycle or to control a center of balance for the motorcycle, reduce unsprung weight for the motorcycle, etc. Embodiments may be selected to allow for improvements in swing arm design, clutch design, shock design, brake design, hub/rim design, and may further use right-angle gears, gear boxes, or other gear designs. Furthermore, embodiments disclosed above may work better for different prime movers. For example, internal combustion engines in motorcycles typically range from 50 cc to 2100 cc. A drivetrain configuration for a 50 cc engine may have different requirements and may therefore differ from a drivetrain for a 2100 cc engine.
In some embodiments, individual customization is possible. For example, a drivetrain may be controlled electronically to reduce torsional vibrations. Electronic control may include using information provided directly by a user or by using feedback from sensors indicating a driving style or intended use of a scooter or motorcycle. There may be certain sensors (including placement of the spacers) used to gather information about the scooter. This may include direct measurement (which might be more accurate but require more sensors) or inferential determination (which would reduce the number of sensors but require more processing, such as noise handling, etc.). Empirical data may be analyzed to determine usable life of components, when components need to be serviced, if a warranty claim is valid, etc. Sensor information on a scooter may be integrated with sensor information received from a smart phone (e.g., getting accelerometer data from a cell phone to determine acceleration speed of the scooter during an event, getting sensor information from sensors on the scooter, and determining a driving or operational style of the rider—hard acceleration vs. easy speed ups, exceeding a maximum vehicle speed limit or weight limit, etc.). In some embodiments, features or functionality may be integrated into a smart phone application that is usable “out of the box” but adapts over time to that user. One possible drawback for any drivetrain architecture is thermal management, especially in architectures in which air cooling is a significant (if not the dominant) factor to consider. Thus, while a compact and lightweight engine behind an aerodynamic fairing may be beneficial, cooling the engine may present additional problems, such as the additional weight, size and costs of a radiator, fluid reservoir and other components of a water-cooled system. If a water-cooled system is not feasible, then the drivetrain itself or architecture of the drivetrain may be limited in terms of what components need higher air flow, which components cannot be located near each other, where components should be located to minimize risk of burning a rider, where components should be located to minimize noise, and the like.
Embodiments illustrated and described herein have several features, no single one of which is solely responsible for its desirable attributes.
In one broad respect, embodiments may be generally directed to a system for lubricating a ball-planetary continuously variable transmission. The CVP may have 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 CVT. The rotatable hub shell is configured for retaining a lubrication fluid. The lubrication system comprises a lubrication tube for supplying lubrication to radially inward components. The lubrication tube comprises a first end extending radially outward with an orifice at the first end and a second end extending radially inward with an opening at the second end. Rotation of the hub shell causes lubrication fluid to enter the orifice, flow along the tube, and exit the opening. In some embodiments, the hub shell has an interior surface, wherein the first end of the tube extends to a radial distance proximate to the interior surface. In some embodiments, the interior surface of the hub shell is smooth or comprises a feature for controlling fluid flow. In some embodiments, the orifice is complementary to a profile of the interior surface. In some embodiments, the orifice cross-section is one of circular, tear drop, angled, or asymmetric. In some embodiments, the feature comprises a circumferential groove, wherein lubrication fluid flows into the circumferential groove. In some embodiments, the orifice is shaped as complementary to the circumferential groove. In some embodiments, the opening and a component of the CVT are located at a same radial position. In some embodiments, the component comprises a spherical planet. In some embodiments, 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. In some embodiments, the tube is fixed to a non-rotatable component of the CVT. In some embodiments, the tube is coupled to a carrier.
The accompanying figures, which are incorporated in and form a part of the specification, illustrate certain features of the inventive embodiments.
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.
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.
For embodiments disclosed with respect to the figures, the following descriptions may be helpful.
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.
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.
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.
As depicted in
As depicted in
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.
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.
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.
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.
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.
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.
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).
As depicted in
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.
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.
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.
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).
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
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.
