WO2018187296A1

WO2018187296A1 - Planetary powertrain configuration with a ball variator continuously variable transmission used as a powersplit

Info

Publication number: WO2018187296A1
Application number: PCT/US2018/025843
Authority: WO
Inventors: Dennis W. PERSON
Original assignee: Dana Limited
Priority date: 2017-04-03
Filing date: 2018-04-03
Publication date: 2018-10-11

Abstract

Provided herein is a continuously variable transmission including: a first rotatable shaft operably coupleable to a source of rotational power, the first rotatable shaft forming a main axis; a variator 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 tiltable axis of rotation, the variator is coaxial with the main axis; a planetary gear set having a sun gear operably coupled to the second traction ring assembly, a planet carrier operably coupled to the first rotatable shaft, and a ring gear coupled to the first traction ring assembly; and a second rotatable shaft arranged coaxial with the first rotatable shaft, the second rotatable shaft operably coupled to the first traction ring assembly and the ring gear.

Description

PLANETARY POWERTRAIN CONFIGURATIONS WITH A BALL VARIATOR CONTINUOUSLY VARIABLE TRANSMISSION USED AS A POWERSPLIT

RELATED APPLICATION

The present application claims the benefit of U.S. Provisional

Application No. 62/480,803 filed on April 3, 2017, which is incorporated herein by reference in its entirety.

BACKGROUND

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 rotational speed. SUMMARY

Provided herein in a continuously variable transmission including a first rotatable shaft operably coupleable to a source of rotational power, the first rotatable shaft forming a main axis; a variator 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 tiltable axis of rotation, the variator is coaxial with the main axis; a planetary gear set having a sun gear operably coupled to the second traction ring assembly, a planet carrier operably coupled to the first rotatable shaft, and a ring gear coupled to the first traction ring assembly; and a second rotatable shaft arranged coaxial with the first rotatable shaft, the second rotatable shaft operably coupled to the first traction ring assembly and the ring gear.

In some embodiments, the continuously variable transmission further includes an input power coupling device operably coupled to the first rotatable shaft.

In some embodiments, the continuously variable transmission further includes a multiple speed gear box operably coupled to the second rotatable shaft. In some embodiments of the continuously variable transmission the variator includes a traction fluid.

In some embodiments, the continuously variable transmission further includes a locking clutch operably coupled to the ring gear and the second rotatable shaft.

Provided herein is a vehicle driveline including a power source, an embodiment of the continuously variable transmission described herein drivingly engaged with the power source, and a vehicle output drivingly engaged with the continuously variable transmission.

In some embodiments of the vehicle driveline the power source is drivingly engaged with the vehicle output.

Provided herein is a vehicle including a continuously variable

transmission described herein.

Provided herein is a method including providing a continuously variable transmission described herein.

Provided herein is a method including providing a vehicle driveline described herein.

Provided herein is a method including providing a vehicle described herein.

INCORPORATION BY REFERENCE

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.

BRIEF DESCRIPTION OF THE DRAWINGS

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 embodiments are utilized, and the accompanying drawings of which: Figure 1 is a side sectional view of a ball-type variator.

Figure 2 is a plan view of a carrier member that is used in the variator of Figure 1.

Figure 3 is an illustrative view of different tilt positions of the ball-type variator of Figure 1.

Figure 4 is a schematic diagram of a preferred embodiment of a continuously variable transmission.

Figure 5 is a schematic diagram of another preferred embodiment of a continuously variable transmission.

Figure 6 is a schematic diagram of another preferred embodiment of a continuously variable transmission.

Figure 7 is a schematic diagram of an embodiment of a vehicle driveline having a continuously variable transmission.

Figure 8 is a partial schematic diagram of another preferred embodiment of a vehicle driveline having a continuously variable transmission.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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 embodiments described.

Continuously Variable Transmissions or CVTs are of many types: belts with variable pulleys, toroidal, and conical, for non-limiting example. The principle of a CVT is that it enables the engine to run at its most efficient rotation speed by changing steplessly the transmission ratio in function of the speed of the car and the torque demand (throttle position) of the driver. If needed for example when accelerating, the CVT can also shift to the most optimum ratio providing more power. A CVT can change the ratio from the minimum to the maximum ratio without any interruption of the power transmission, as opposed to the opposite of usual transmissions which require an interruption of the power transmission by disengaging to shift from one discrete ratio to engage the next ratio.

Provided herein are configurations of continuously variable

transmissions (CVTs) based on a ball-type variators, also known as CVPs, for continuously variable planetary. Basic concepts of a ball-type Continuously Variable Transmissions are described in United States Patent No. 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 (first) traction ring 2, an output (second) traction ring 3, and an idler (sun) assembly 4 as shown on FIG. 1. The balls are mounted on tiltable axles 5, themselves held in a carrier (stator, cage) assembly having a first carrier member 6 operably coupled to a second carrier member 7. The first carrier member 6 rotates with respect to the second carrier member 7, and vice versa.

In some embodiments, the first carrier member 6 is fixed from rotation while the second carrier member 7 is configured to rotate with respect to the first carrier member, and vice versa.

In one embodiment, the first carrier member 6 is provided with a number of radial guide slots 8. The second carrier member 7 is provided with a number of radially offset guide slots 9, as illustrated in FIG. 2. The radial guide slots 8 and the radially offset guide slots 9 are adapted to guide the tiltable axles 5, The axles 5 are adjusted to achieve a desired ratio of input speed to output speed during operation of the CVT.

In some embodiments, adjustment of the axles 5 involves control of the position of the first 6 and second carrier members 7 to impart a tilting of the axles 5 and thereby causing a tilting of the balls' axes of rotation to adjust the speed ratio of the variator.

In other embodiments, the CVT can be a belt-and-pulley, toroidal-type variator, or other known continuously variable device and appropriate gearing. While the figures and description herein are directed to ball-type variators (CVTs), alternate embodiments are contemplated another version of a variator (CVT), such as a Variable-diameter pulley (VDP) or Reeves drive, a toroidal or roller-based CVT (Extroid CVT), a Magnetic CVT or mCVT, Ratcheting CVT, Hydrostatic CVTs, Naudic Incremental CVT (iCVT), Cone CVTs, Radial roller CVT, Planetary CVT, or any other version CVT.

The working principle of such a CVP of FIG. 1 is shown on FIG. 3. The

CVP itself works with a traction fluid. The lubricant between the ball and the conical rings acts as a solid at high pressure, transferring the power from the input ring, through the balls, to the output ring. By tilting the balls' axes, the ratio is changed between input and output. When the axis is horizontal the ratio is one-to-one (1 :1) illustrated in FIG. 3. When the axis is tilted the distance between the axis and the contact point change, modifying the overall ratio. All the balls' axes are tilted at the same time with a mechanism included in the carrier and/or idler.

Embodiments disclosed here are related to the control of a variator and/or a CVT using generally spherical planets each having a tiltable axis of rotation that are adjusted to achieve a desired ratio of input speed to output speed during operation.

In some embodiments, adjustment of said axis of rotation involves angular misalignment of the planet axis in a first plane in order to achieve an angular adjustment of the planet axis in a second plane that is perpendicular to the first plane, thereby adjusting the speed ratio of the variator. The angular misalignment in the first plane is referred to here as "skew", "skew angle", and/or "skew condition".

In one embodiment, a control system coordinates the use of a skew angle to generate forces between certain contacting components in the variator that will tilt the planet axis of rotation. The tilting of the planet axis of rotation adjusts the speed ratio of the variator.

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 1011 A and bearing 1011 B) 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 frictionai forces between the elements. For the purposes of this disclosure, it should be understood that the CVTs described here operate in both tractive and frictionai 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 FIG. 4, in some embodiments, a continuously variable transmission (CVT) 10 is provided with a first rotatable shaft 1 1 adapted to receive power from a source of rotational power.

In some embodiments, the first rotatable shaft 1 1 is operably coupled to a torque converter device, or other common input coupling device 40 as depicted in FIG. 6.

In some embodiments, the first rotatable shaft 1 1 forms a main axis A.

The CVT 10 is provided with a variator (CVP) 12 aligned coaxially with the first rotatable shaft 1 1.

In some embodiments, the variator 12 is similar to the variator depicted in FIGS. 1 -3. The variator 12 includes a first traction ring assembly 13 and a second traction ring assembly 14 in contact with a number of balls.

In some embodiments, the CVT 10 includes a planetary gear set 15 aligned coaxially with the first rotatable shaft 1 1 and the variator 12. The planetary gear set 15 includes a ring gear 16, a planet carrier 17, and a sun gear 18.

In some embodiments, the planet carrier 17 is coupled to the first rotatable shaft 1 1. The sun gear 18 is operably coupled to the second traction ring assembly 14. The ring gear 16 is coupled to the first traction ring assembly 13 and a second rotatable shaft 19.

In some embodiments, the second rotatable shaft 19 is coaxial with the first rotatable shaft 1 1.

In some embodiments, the second rotatable shaft 19 is configured to transmit a power out of the CVT 10 to a multiple speed gear box, fixed ratio gearing, or other known power transmission mechanisms.

Basic concepts of power transmissions and mechanisms used with continuously variable transmissions are described in pending are described in Patent Cooperation Treaty Application Nos. PCT/US17/033,452,

PCT/US 17/033,456, PCT/US17/033,463, PCT/US17/033,445 and United States Patent Application No. 15/474, 120 incorporated herein by reference in their entirety.

During operation of the CVT 10, a power transmitted through the first rotatable shaft 1 1 drives the planet carrier 17 to thereby transmit power to the sun gear 18 and the ring gear 16. The sun gear 18 transmits rotational power to the second traction ring assembly 14. The ring gear 16 transmits rotational power to the first traction ring assembly 13.

In some embodiments, power is transmitted out of the CVT 10 on the second rotatable shaft 19. These embodiments provide a reduced length powersplit mechanism.

In some embodiments, a locking clutch is placed between the ring gear 16 and the sun gear 18, or the ring gear 16 and the planet carrier 17.

In some embodiments, as shown in FIG. 5, the CVT 10 includes a locking clutch 20 operably coupled to the ring gear 16 and the second rotatable shaft 19.

It should be appreciated that the locking clutch 20 disclosed herein is optionally configured as a wet clutch, dry clutch, synchronizer clutch, one-way clutch, or mechanical diode.

In some embodiments, the CVT 10 is drivingly engaged with a power source (not shown) and a vehicle output as part of a vehicle driveline 100, as depicted in FIG. 7. In some embodiments, the vehicle driveline includes a source of rotational power 100, a differential 102 assembly and a torsional damper 101 . In some configurations, this damper 101 can be coupled with a clutch for the starting function.

In some embodiments, the CVT 10 is coupled to a multiple speed gear box 30, fixed ratio gearing, or other known power transmission mechanisms as shown in FIG. 8.

In some embodiments, the first rotatable shaft 1 1 is adapted to be operably coupleable to a source of rotational power and the second rotatable shaft 19 is configured to transmit power out of the CVT 10.

In some embodiments, the first rotatable shaft 1 1 is adapted to transmit power out of the CVT and the second rotatable shaft 19 is adapted to operably couple to a source of rotational power.

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.

Aspects of the invention include:

Aspect 1 : A continuously variable transmission comprising:

a first rotatable shaft operably coupleable to a source of rotational power, the first rotatable shaft forming a main axis;

a variator 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 tiltable axis of rotation, the variator is coaxial with the main axis; a planetary gear set having a sun gear operably coupled to the second traction ring assembly, a planet carrier operably coupled to the first rotatable shaft, and a ring gear coupled to the first traction ring assembly; and

a second rotatable shaft arranged coaxial with the first rotatable shaft, the second rotatable shaft operably coupled to the first traction ring assembly and the ring gear.

Aspect 2. The continuously variable transmission of Aspect 1 , further comprising an input power coupling device operably coupled to the first rotatable shaft.

Aspect 3. The continuously variable transmission of Aspect 2, further comprising a multiple speed gear box operably coupled to the second rotatable shaft.

Aspect 4. The continuously variable transmission of any one of Aspects 1-3, wherein the variator comprises a traction fluid. Aspect 5. The continuously variable transmission of any one of Aspects 1-4 further comprising a locking clutch operably coupled to the ring gear and the second rotatable shaft. Aspect 6. A vehicle driveline comprising: a power source, a continuously variable transmission of any of Aspects 1-5 drivingly engaged with the power source, and a vehicle output drivingly engaged with the continuously variable transmission. Aspect 7. The vehicle driveline of Aspect 6, wherein the power source is drivingly engaged with the vehicle output.

Aspect 8. A vehicle comprising the continuously variable transmission of any one of Aspects 1-5.

Aspect 9. A method comprising providing a continuously variable transmission of any one of Aspects 1-5.

Aspect 10. A method comprising providing a vehicle driveline of Aspect 6 or 7.

Aspect 11. A method comprising providing a vehicle of Aspect 8.

Claims

WHAT IS CLAIMED IS:

1. A continuously variable transmission comprising:

2. The continuously variable transmission of Claim 1 , further comprising an input power coupling device operably coupled to the first rotatable shaft.

3. The continuously variable transmission of Claim 2, further comprising a multiple speed gear box operably coupled to the second rotatable shaft.

4. The continuously variable transmission of any one of Claims 1-3, wherein the variator comprises a traction fluid.

5. The continuously variable transmission of any one of Claims 1-4 further comprising a locking clutch operably coupled to the ring gear and the second rotatable shaft.

6. A vehicle driveline comprising: a power source, a continuously variable transmission of any of Claims 1-5 drivingly engaged with the power source, and a vehicle output drivingly engaged with the continuously variable transmission.

7. The vehicle driveline of Claim 6, wherein the power source is drivingly engaged with the vehicle output.

8. A vehicle comprising the continuously variable transmission of any one of Claims 1-5.

9. A method comprising providing a continuously variable

transmission of any one of Claims 1-5.

10. A method comprising providing a vehicle driveline of Claim 6 or 7.

11. A method comprising providing a vehicle of Claim 8.