Patent Application
20170284508
A driveline including a continuously variable transmission allows an operator or a control system to vary a drive ratio in a stepless manner, permitting a power source to operate at its most advantageous operating point.
Provided herein is a continuously variable transmission including a first rotatable shaft operably coupleable to a source of rotational power; a second rotatable shaft aligned coaxial with the first rotatable shaft, the first rotatable shaft and the second rotatable shaft forming a main axis; a variator assembly having a first traction ring assembly and a second traction ring assembly in contact with a plurality of balls, wherein each ball of the plurality of balls has a tillable axis of rotation, the variator assembly is coaxial with the main axis; a first planetary gearset having a first sun gear operably coupled to the second rotatable shaft, a first planet carrier operably coupled to the first rotatable shaft, and a first ring gear coupled to the second traction ring assembly; a first-and-third mode clutch operably coupled to the first ring gear, the first-and-third mode clutch coaxial with the main axis; a countershaft arranged parallel to the main axis; a second planetary gear set coaxial with the countershaft, the second planetary gear set having a second sun gear, a second planet carrier, and a second ring gear; a third planetary gear set coaxial with the countershaft, the third planetary gear set having a third sun gear, a third planet carrier, and a third ring gear; a second-and-fourth mode clutch coaxial with the countershaft, the second-and-fourth mode clutch operably coupled to the second sun gear and the third sun gear; a first synchronizer clutch coaxial with the countershaft, the first synchronizer clutch operably coupled to the second ring gear; and a second synchronizer clutch coaxial with the countershaft, the second synchronizer clutch operably coupled to the third ring gear.
Provided herein is a method of operating a continuously variable transmission, the method including providing a continuously variable transmission including: a first rotatable shaft operably coupleable to a source of rotational power; a second rotatable shaft aligned coaxial with the first rotatable shaft, the first rotatable shaft and the second rotatable shaft forming a main axis; a variator assembly having a first traction ring assembly and a second traction ring assembly in contact with a plurality of balls, wherein each ball of the plurality of balls has a tillable axis of rotation, the variator assembly is coaxial with the main axis; a first planetary gearset having a first sun gear operably coupled to the second rotatable shaft, a first planet carrier operably coupled to the first rotatable shaft, and a first ring gear coupled to the second traction ring assembly; a first-and-third mode clutch operably coupled to the first ring gear, the first-and-third mode clutch coaxial with the main axis; a countershaft arranged parallel to the main axis; a second planetary gear set coaxial with the countershaft, the second planetary gear set having a second sun gear, a second planet carrier, and a second ring gear; a third planetary gear set coaxial with the countershaft, the third planetary gear set having a third sun gear, a third planet carrier, and a third ring gear; a second-and-fourth mode clutch coaxial with the countershaft, the second-and-fourth mode clutch operably coupled to the second sun gear and the third sun gear; a first synchronizer clutch coaxial with the countershaft, the first synchronizer clutch operably coupled to the second ring gear; and a second synchronizer clutch coaxial with the countershaft, the second synchronizer clutch operably coupled to the third ring gear; engaging the first-and-third mode clutch to operate in a first mode of operation and a third mode of operation; engaging the second-and-fourth mode clutch to operate in a second mode of operation and a fourth mode of operation.
Provided herein is a vehicle driveline including a power source, a variable transmission of any of described herein drivingly engaged with the power source, and a vehicle output drivingly engaged with the variable transmission.
Provided herein is a vehicle including the variable transmission of any one of the transmissions described herein.
Provided herein is a method including providing a variable transmission of any one of the transmissions described herein.
Provided herein is a method including providing a vehicle driveline of the kind described herein.
Provided herein is a method including providing a vehicle having any one of the transmission described herein.
All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference.
The novel features of the preferred embodiments are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present embodiments will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the preferred embodiments are utilized, and the accompanying drawings of which:
The preferred embodiments will now be described with reference to the accompanying figures, wherein like numerals refer to like elements throughout. The terminology used in the descriptions below is not to be interpreted in any limited or restrictive manner simply because it is used in conjunction with detailed descriptions of certain specific embodiments. Furthermore, the preferred embodiments includes several novel features, no single one of which is solely responsible for its desirable attributes or which is essential to practicing the preferred embodiments described.
Provided herein are configurations of continuously variable transmissions (CVTs) based on a ball type variators, also known as CVP, for continuously variable planetary. Basic concepts of a ball type Continuously Variable Transmissions are described in U.S. Pat. Nos. 8,469,856 and 8,870,711 incorporated herein by reference in their entirety. Such a CVT, adapted herein as described throughout this specification, includes a number of balls (planets, spheres) 1, depending on the application, two ring (disc) assemblies with a conical surface in contact with the balls, an input traction ring 2, an output traction ring 3, and an idler (sun) assembly 4 as shown on
The working principle of such a CVP of
For description purposes, the term “radial” is used here to indicate a direction or position that is perpendicular relative to a longitudinal axis of a transmission or variator. The term “axial” as used here refers to a direction or position along an axis that is parallel to a main or longitudinal axis of a transmission or variator. For clarity and conciseness, at times similar components labeled similarly (for example, bearing 1011A and bearing 1011B) will be referred to collectively by a single label (for example, bearing 1011).
As used here, the terms “operationally connected,” “operationally coupled”, “operationally linked”, “operably connected”, “operably coupled”, “operably linked,” “operably coupleable” and like terms, refer to a relationship (mechanical, linkage, coupling, etc.) between elements whereby operation of one element results in a corresponding, following, or simultaneous operation or actuation of a second element. It is noted that in using said terms to describe inventive embodiments, specific structures or mechanisms that link or couple the elements are typically described. However, unless otherwise specifically stated, when one of said terms is used, the term indicates that the actual linkage or coupling take a variety of forms, which in certain instances will be readily apparent to a person of ordinary skill in the relevant technology.
It should be noted that reference herein to “traction” does not exclude applications where the dominant or exclusive mode of power transfer is through “friction.” Without attempting to establish a categorical difference between traction and friction drives here, generally these are typically understood as different regimes of power transfer. Traction drives usually involve the transfer of power between two elements by shear forces in a thin fluid layer trapped between the elements. The fluids used in these applications usually exhibit traction coefficients greater than conventional mineral oils. The traction coefficient (μ) represents the maximum available traction force which would be available at the interfaces of the contacting components and is the ratio of the maximum available drive torque per contact force. Typically, friction drives generally relate to transferring power between two elements by frictional forces between the elements. For the purposes of this disclosure, it should be understood that the CVTs described here operate in both tractive and frictional applications. For example, in the embodiment where a CVT is used for a bicycle application, the CVT operates at times as a friction drive and at other times as a traction drive, depending on the torque and speed conditions present during operation.
Referring now to
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Typically, synchronizer mechanisms (referred to herein as “synchronizer clutch”) used in power transmissions include a dog clutch integrated with a speed-matching device such as a cone-clutch. During operation of the transmission, if the dog teeth of the dog clutch make contact with a gear, and the two parts are spinning at different speeds, the teeth will fail to engage and a loud grinding sound will be heard as they clatter together. For this reason, a synchronizer mechanism or synchronizer clutch is used, which consists of a cone clutch. Before the teeth engage, the cone clutch engages first, which brings the two rotating elements to the same speed using friction. Until synchronization occurs, the teeth are prevented from making contact. It should be appreciated that the exact design of the synchronizer clutch is within a designer's choice for satisfying packaging and performance requirements. A synchronizer clutch is optionally configured to be a two position clutch having an engaged position and a neutral (or free) position. A synchronizer clutch is optionally configured to be a three position clutch having a first engaged position, a second engaged position, and a neutral position. Embodiments disclosed herein use synchronizer clutches to enable the pre-selection of gear sets by a control system (not shown) for smooth transition between operating modes of the transmission. It should be appreciated that the powertrain configurations disclosed herein are optionally configured with other types of selectable torque transmitting devices including, and not limited to, wet clutches, dry clutches, dog clutches, and electromagnetic clutches, among others.
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It should be noted that the description above has provided dimensions for certain components or subassemblies. The mentioned dimensions, or ranges of dimensions, are provided in order to comply as best as possible with certain legal requirements, such as best mode. However, the scope of the embodiments described herein are to be determined solely by the language of the claims, and consequently, none of the mentioned dimensions is to be considered limiting on the inventive embodiments, except in so far as any one claim makes a specified dimension, or range of thereof, a feature of the claim.
While preferred embodiments have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the preferred embodiments. It should be understood that various alternatives to the embodiments described herein may be employed in practicing the preferred embodiments. It is intended that the following claims define the scope of the preferred embodiments and that methods and structures within the scope of these claims and their equivalents be covered thereby.
The present application claims priority to and the benefit from Provisional U.S. Patent Application Ser. No. 62/315,369 filed on Mar. 30, 2016. The content of the above-noted patent application is hereby expressly incorporated by reference into the detailed description of the present application.
| Number | Date | Country | |
|---|---|---|---|
| 62315369 | Mar 2016 | US |
