Patent Application
20170227122
Continuously variable transmissions (CVT) and transmissions that are substantially continuously variable are increasingly gaining acceptance in various applications. The process of controlling the ratio provided by the CVT is complicated by the continuously variable or minute gradations in ratio presented by the CVT. Furthermore, the range of ratios that are available to be implemented in a CVT are not be sufficient for some applications. A transmission is capable of implementing a combination of a CVT with one or more additional CVT stages, one or more fixed ratio range splitters, or some combination thereof in order to extend the range of available ratios. The combination of a CVT with one or more additional stages further complicates the ratio control process, as the transmission will have multiple configurations that achieve the same final drive ratio.
The different transmission configurations could for example, multiply input torque across the different transmission stages in different manners to achieve the same final drive ratio. However, some configurations provide more flexibility or better efficiency than other configurations providing the same final drive ratio.
The criteria for optimizing transmission control could be different for different applications of the same transmission. For example, the criteria for optimizing control of a transmission for fuel efficiency will differ based on the type of prime mover applying input torque to the transmission. Furthermore, for a given transmission and prime mover pair, the criteria for optimizing control of the transmission will differ depending on whether fuel efficiency or performance is being optimized.
Provided herein is a computer-implemented system for a vehicle having an engine coupled to a continuously variable transmission having a ball-planetary variator (CVP), the computer-implemented system including: a digital processing device including an operating system configured to perform executable instructions and a memory device; a computer program including instructions executable by the digital processing device to create an application including a software module configured to manage a plurality of vehicle driving conditions; a plurality of sensors configured to monitor vehicle parameters including: CVP Speed Ratio, CVP Input Torque, CVP position, wherein the software module is configured to execute a feed-forward sub-module, wherein the feed-forward sub-module includes a base ratio-to-position calibration map configured to store values of a CVP position based at least in part on the CVP input torque and the CVP speed ratio.
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:
An electronic controller is described herein that enables electronic control over a variable ratio transmission having a continuously variable ratio portion, such as a Continuously Variable Transmission (CVT), Infinitely Variable Transmission (IVT), or variator. The electronic controller could be configured to receive input signals indicative of parameters associated with an engine coupled to the transmission. The parameters could include throttle position sensor values, accelerator pedal position sensor values, vehicle speed, gear selector position, user-selectable mode configurations, and the like, or some combination thereof. The electronic controller could also receive one or more control inputs. The electronic controller could determine an active range and an active variator mode based on the input signals and control inputs. The electronic controller could control a final drive ratio of the variable ratio transmission by controlling one or more electronic actuators and/or solenoids that control the ratios of one or more portions of the variable ratio transmission.
The electronic controller described herein is described in the context of a continuous variable transmission, such as the continuous variable transmission of the type described in U.S. patent Application No. 14/425,842, entitled “3-Mode Front Wheel Drive And Rear Wheel Drive Continuously Variable Planetary Transmission” and, U.S. Patent Application Ser. No. 62/158,847, entitled “Control Method of Synchronous Shifting of a Multi-Range Transmission Comprising a Continuously Variable Planetary Mechanism”, each assigned to the assignee of the present application and hereby incorporated by reference herein in its entirety. However, the electronic controller is not limited to controlling a particular type of transmission but rather, could be configured to control any of several types of variable ratio transmissions.
Provided herein are configurations of CVTs based on a ball type variator, also known as CVP, for continuously variable planetary. Basic concepts of a ball type Continuously Variable Transmissions are described in U.S. Pat. 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, comprises a number of balls (planets, spheres) 1, depending on the application, two ring (disc) assemblies with a conical surface contact with the balls, as input traction ring 2 and 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 “torque threshold”, as used herein, indicates a calibrateable value of torque at which a designer desires a control sub-module to enable operation or dis-able operation.
As used here, the terms “operationally connected,” “operationally coupled”, “operationally linked”, “operably connected”, “operably coupled”, “operably coupleable”, “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 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 will take a variety of forms, which in certain instances will be readily apparent to a person of ordinary skill in the relevant technology.
For description purposes, the term “radial”, as used herein indicates a direction or position that is perpendicular relative to a longitudinal axis of a transmission or variator. The term “axial” as used herein 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).
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 herein, generally, these are 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 forces that would be available at the interfaces of the contacting components and is a measure of the maximum available drive torque. 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 could operate in both tractive and frictional applications. As a general matter, the traction coefficient μ is a function of the traction fluid properties, the normal force at the contact area, and the velocity of the traction fluid in the contact area, among other things. For a given traction fluid, the traction coefficient μ increases with increasing relative velocities of components, until the traction coefficient μ reaches a maximum capacity after which the traction coefficient μ decays. The condition of exceeding the maximum capacity of the traction fluid is often referred to as “gross slip condition”. Traction fluid is also influenced by entrainment speed of the fluid and temperature at the contact patch, for example, the traction coefficient is generally highest near zero speed and decays as a weak function of speed. The traction coefficient often improves with increasing temperature until a point at which the traction coefficient rapidly degrades.
As used herein, “creep”, “ratio droop”, or “slip” is the discrete local motion of a body relative to another and is exemplified by the relative velocities of rolling contact components such as the mechanism described herein. In traction drives, the transfer of power from a driving element to a driven element via a traction interface requires creep. Usually, creep in the direction of power transfer, is referred to as “creep in the rolling direction.” Sometimes the driving and driven elements experience creep in a direction orthogonal to the power transfer direction, in such a case this component of creep is referred to as “transverse creep.”
For description purposes, the terms “prime mover”, “engine,” and like terms, are used herein to indicate a power source. Said power source could be fueled by energy sources including hydrocarbon, electrical, biomass, nuclear, solar, geothermal, hydraulic, pneumatic, and/or wind to name but a few. Although typically described in a vehicle or automotive application, one skilled in the art will recognize the broader applications for this technology and the use of alternative power sources for driving a transmission including this technology.
Those of skill will recognize that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein, including with reference to the transmission control system described herein, for example, could be implemented as electronic hardware, software stored on a computer readable medium and executable by a processor, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans could implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present embodiments. For example, various illustrative logical blocks, modules, and circuits described in connection with the embodiments disclosed herein could be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor could be a microprocessor, but in the alternative, the processor could be any conventional processor, controller, microcontroller, or state machine. A processor could also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. Software associated with such modules could reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other suitable form of storage medium known in the art. An exemplary storage medium is coupled to the processor such the processor reads information from, and write information to, the storage medium. In the alternative, the storage medium could be integral to the processor. The processor and the storage medium could reside in an ASIC. For example, in one embodiment, a controller for use of control of the IVT includes a processor (not shown).
Referring now to
Referring now to
In one embodiment, the speed ratio control sub-module 112 includes a feed-forward sub-module 119 adapted to receive the commanded CVP ratio signal 115 and a CVP input torque signal 120. The CVP input torque signal 120 is received from other sub-modules in the transmission control module 104 and is indicative of an input torque magnitude applied to the CVP. The feed-forward sub-module 119 determines a ratio control feed-forward signal 121 that is summed with the output signal 117 to form a ratio command signal 122. The ratio command signal 122 is used by other sub-modules of the transmission control module 104 to adjust the CVP during operation.
Referring now to
Still referring to
Still referring to
In one embodiment, the feed-forward sub-module 119 includes a short-term adaptive control sub-module 152 configured to receive the enable command signal 145. During operation, when the enable command signal 145 is true, the short-term adaptive control sub-module 152 executes instructions to populate the values of the short-term ratio-to-position calibration map 147 based at least in part on the CVP position signal 132 and the summed value of the base adaptive control signal 149 and the short-term ratio-to-position control signal 150. The summed value of the base adaptive control signal 149 and the short-term ratio-to-position control signal 150 is the ratio control feed forward signal 121. The ratio control feed forward signal 121 is passed out of the feed-forward sub-module 119 for use in the speed ratio control sub-module 112. The feed-forward sub-module 119 includes a long-term adaptive control write sub-module 153 and a long-term adaptive control read sub-module 154. The long-term adaptive control write sub-module 153 receives the write command signal 142 from the state machine 140. The long-term adaptive control write sub-module 153 is configured to compute a moving average of the long-term control signal values 151 generated during operation. The long-term adapted control write sub-module 153 is also configured to compute the moving average of the current short-term control signal values 150. The long-term control write sub-module 153 is configured to write the computed moving averages to memory based at least in part on the write command signal 142. The long-term adaptive control read sub-module 154 receives the read command signal 143 from the state machine 140. The long-term adaptive control read sub-module 154 is configured to read stored values of the long-term ratio-to-position calibration map 148 from memory and populate the short-term ratio-to-position calibration map 147 with said values based at least in part on the read command signal 143.
Passing now to
Boolean block 169 receives inverse of the resulting signals from the first evaluation block 162 and the second evaluation block 166. The Boolean block 169 receives the master enable signal 131 and the enable adaptive control signal 141. In one embodiment, the adaptive enable sub-module 144 receives the CVP position signal 132 that is passed to a third evaluation block 170. The third evaluation block 170 compares the CVP position signal 132 to upper and lower threshold values that are optionally configured to be calibration variables. The third evaluation block 170 passes a true signal when the CVP position signal 132 is between the upper and lower threshold values. A difference between the CVP position signal 132 and the CVP position signal 132 of the previous computational step is passed to a comparison block 171. The comparison block 171 compares the difference to a product of a maximum rate calibration variable 172 and a time step calibration variable 173. In other words, the comparison block 171 compares the change in the CVP position signal 132 between computational time steps to a maximum rate of change and passes a true signal if the change is less than the maximum. The comparison block 171 passes the result to the Boolean block 169. The Boolean block 169 determines the enable command signal 145 based on the input signals described.
Turning now to
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.
The foregoing description details certain embodiments. It will be appreciated, however, that no matter how detailed the foregoing appears in text, the preferred embodiments are practiced in many ways. As is also stated above, it should be noted that the use of particular terminology when describing certain features or aspects of the preferred embodiments should not be taken to imply that the terminology is being re-defined herein to be restricted to including any specific characteristics of the features or aspects of the embodiments with which that terminology is associated.
While preferred embodiments of the present 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 could be employed in practice. 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.
This application claims the benefit of U.S. Provisional Application No. 62/291,660 filed on Feb. 5, 2016, which is herein incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62291660 | Feb 2016 | US |
