Infinitely variable transmissions (IVT) and continuously variable transmissions (CVT) are becoming more in demand for a variety of vehicles as they offer performance and efficiency improvements over standard fixed gear transmissions. Certain types of IVTs and CVTs that employ ball-type continuously variable planetary (CVP) transmissions often have shift actuators coupled to the CVP for control of speed ratio during operation of the transmission. Implementation of a CVT into a vehicle can improve vehicle performance and efficiency. However, some continuously variable transmissions have unique operating characteristics compared to traditional geared transmissions. It is desirable for the transmission control system to manage the CVT under all operating conditions the vehicle will encounter in the most efficient means possible. Therefore a new control method is needed to select operating conditions for the CVT that optimize the overall efficiency and performance of the powertrain.
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 CVP having a plurality of balls, each ball provided with a tiltable axis of rotation, each ball supported in a carrier assembly, the carrier assembly operably coupled to a shift actuator, the computer-implemented system comprising: a digital processing device comprising an operating system configured to perform executable instructions and a memory device; a computer program including instructions executable by the digital processing device, the computer program comprising a software module configured to manage the CVP and the engine; a plurality of sensors configured to monitor vehicle parameters comprising: a transmission output shaft speed sensor configured to sense an engine speed, an engine speed sensor configured to sense an engine speed, an engine torque sensor configured to sense an engine torque, a vehicle speed sensor configured to sense a vehicle speed, a CVP ratio indicator configured to indicate a CVP ratio, and a commanded transmission output torque indicator configured to indicate a commanded transmission output torque; wherein the software module is adapted to determine a commanded CVP ratio based at least in part on the commanded transmission output torque, the transmission output shaft speed, the engine speed, the engine torque, and the vehicle speed.
In some embodiments of the computer-implemented system, the software module further comprises a solution set generator, a sub-system loss model, and a total system loss sub-module.
In some embodiments of the computer-implemented system, the sub-system loss sub-module further comprises a CVP loss sub-system module.
In some embodiments of the computer-implemented system, the sub-system loss sub-module further comprises an engine loss sub-system module.
In some embodiments of the computer-implemented system, the sub-system loss sub-module further comprises a hydraulic pump loss sub-system module.
In some embodiments of the computer-implemented system, the sub-system loss sub-module further comprises a torque converter loss sub-system module.
In some embodiments of the computer-implemented system, the total system loss sub-module is configured to determine the minimum total loss from a set of operating conditions.
In some embodiments of the computer-implemented system, the set of operating conditions are determined in the solution set generator.
In some embodiments of the computer-implemented system, the solution set generator determines a set of operating conditions that satisfy the commanded transmission output torque.
In some embodiments of the computer-implemented system, the total system loss sub-module is configured to determine a commanded CVP ratio based at least in part on the minimum total loss.
In some embodiments of the computer-implemented system, the solution set generator is configured to determine a set of CVP ratio solutions based at least in part on the vehicle speed and the commanded transmission output torque.
In some embodiments of the computer-implemented system, the solution set generator is configured to determine a set of engine speed solutions and a set of engine torque solutions, wherein the set of engine speed solutions and the set of engine torque solutions are based at least in part on the set of CVP ratio solutions.
In some embodiments of the computer-implemented system, the total system loss sub-module further comprises a total loss minimization function.
In some embodiments of the computer-implemented system, the total loss minimization function is configured to execute a process, the process comprising the steps of: receiving a total loss set comprising an indexed array of solutions for total system loss; receiving an input power set comprising an indexed array of solutions for input power; comparing the input power set to a requested input power signal; and selecting a minimum total loss operating condition based at least in part on the comparison of the requested input power signal to the input power set.
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 invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which:
Described herein is a control system for a vehicle having a continuously variable transmission (CVT) having a ball planetary variator (CVP), providing a smooth and controlled operation. In some embodiments, the control system implements an optimization sub-module. System losses in a CVP equipped vehicle consist of the following: CVP efficiency losses, hydraulic pump losses, clutch energy losses, mode shift losses, torque converter losses, and engine losses (defined as deviation from best Brake Specific Fuel Consumption (BSFC) point), among others. Driver torque demand can be satisfied by an infinite combination of operating points consisting of a chosen engine operating point, CVP ratio, and mode selection. The required clamping load and line pressure requirements resulting from these choices further influences losses. Methods described herein will select system operating point that minimizes total system loss.
Provided herein are configurations of CVTs based on 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, 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 ring 2 and output ring 3, and an idler (sun) assembly 4 as shown on
The working principle of such a CVP of
As used here, the terms “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 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” 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).
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 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 which 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 will 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”.
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 can be fueled by energy sources comprising 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 comprising this technology.
For description purposes, the terms “electronic control unit”, “ECU”, “Driving Control Manager System” or “DCMS” are used interchangeably herein to indicate a vehicle's electronic system that controls subsystems monitoring or commanding a series of actuators on an internal combustion engine to ensure optimal engine performance. It does this by reading values from a multitude of sensors within the engine bay, interpreting the data using multidimensional performance maps (called lookup tables), and adjusting the engine actuators accordingly. Before ECUs, air-fuel mixture, ignition timing, and idle speed were mechanically set and dynamically controlled by mechanical and pneumatic means.
Those of skill will recognize that brake position and throttle position sensors can be electronic, and in some cases, well-known potentiometer type sensors. These sensors can provide a voltage or current signal that is indicative of a relative rotation and/or compression/depression of driver control pedals, for example, brake pedal and/or throttle pedal. Often, the voltage signals transmitted from the sensors are scaled. A convenient scale used in the present application as an illustrative example of one implementation of the control system uses a percentage scale 0%-100%, where 0% is indicative of the lowest signal value, for example a pedal that is not compressed, and 100% is indicative of the highest signal value, for example a pedal that is fully compressed. In some embodiments, there are implementations of the control system where the brake pedal is effectively fully engaged with a sensor reading of 20%-100%. Likewise, in some embodiments, a fully engaged throttle pedal corresponds to a throttle position sensor reading of 20%-100%. The sensors, and associated hardware for transmitting and calibrating the signals, can be selected in such a way as to provide a relationship between the pedal position and signal to suit a variety of implementations. Numerical values given herein are included as examples of one implementation and not intended to imply limitation to only those values. For example, in some embodiments, a minimum detectable threshold for a brake pedal position is 6% for a particular pedal hardware, sensor hardware, and electronic processor. Whereas an effective brake pedal engagement threshold is 14%, and a maximum brake pedal engagement threshold begins at or about 20% compression. As a further example, in some embodiments, a minimum detectable threshold for an accelerator pedal position is 5% for a particular pedal hardware, sensor hardware, and electronic processor. In some embodiments, similar or completely different pedal compression threshold values for effective pedal engagement and maximum pedal engagement are also applied for the accelerator pedal.
Those of skill will recognize that in some embodiments, 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, are 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 may 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 invention. For example, various illustrative logical blocks, modules, and circuits described in connection with the embodiments disclosed herein are 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 may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. In some embodiments, a processor will 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. In some embodiments, software associated with such modules resides 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. In some embodiments, an exemplary storage medium is coupled to the processor such that the processor reads information from, and writes information to, the storage medium. In alternative embodiments, the storage medium is integral to the processor. In some embodiments, the processor and the storage medium reside in an ASIC. For example, in one embodiment, a controller for use of control of the IVT comprises a processor (not shown).
Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. Any reference to “or” herein is intended to encompass “and/or” unless otherwise stated.
In some embodiments, the Control System for a Vehicle equipped with an infinitely variable transmission described herein includes a digital processing device, or use of the same. In further embodiments, the digital processing device includes one or more hardware central processing units (CPU) that carry out the device's functions. In still further embodiments, the digital processing device further comprises an operating system configured to perform executable instructions. In some embodiments, the digital processing device is optionally connected a computer network. In further embodiments, the digital processing device is optionally connected to the Internet such that it accesses the World Wide Web. In still further embodiments, the digital processing device is optionally connected to a cloud computing infrastructure. In other embodiments, the digital processing device is optionally connected to an intranet. In other embodiments, the digital processing device is optionally connected to a data storage device.
In some embodiments, the device includes a storage and/or memory device. The storage and/or memory device is one or more physical apparatuses used to store data or programs on a temporary or permanent basis. In some embodiments, the device is volatile memory and requires power to maintain stored information. In some embodiments, the device is non-volatile memory and retains stored information when the digital processing device is not powered. In further embodiments, the non-volatile memory comprises flash memory. In some embodiments, the non-volatile memory comprises dynamic random-access memory (DRAM). In some embodiments, the non-volatile memory comprises ferroelectric random access memory (FRAM). In some embodiments, the non-volatile memory comprises phase-change random access memory (PRAM). In other embodiments, the device is a storage device including, by way of non-limiting examples, CD-ROMs, DVDs, flash memory devices, magnetic disk drives, magnetic tapes drives, optical disk drives, and cloud computing based storage. In further embodiments, the storage and/or memory device is a combination of devices such as those disclosed herein.
In some embodiments, the digital processing device includes an input device to receive information from a user. In some embodiments, the input device is a keyboard. In some embodiments, the input device is a pointing device including, by way of non-limiting examples, a mouse, trackball, track pad, joystick, game controller, or stylus. In some embodiments, the input device is a touch screen or a multi-touch screen. In other embodiments, the input device is a microphone to capture voice or other sound input. In other embodiments, the input device is a video camera or other sensor to capture motion or visual input. In further embodiments, the input device is a Kinect, Leap Motion, or the like. In still further embodiments, the input device is a combination of devices such as those disclosed herein.
In some embodiments the Control System for a Vehicle equipped with an infinitely variable transmission disclosed herein includes one or more non-transitory computer readable storage media encoded with a program including instructions executable by the operating system of an optionally networked digital processing device. In further embodiments, a computer readable storage medium is a tangible component of a digital processing device.
In some embodiments, the Control System for a Vehicle equipped with a continuously variable transmission disclosed herein includes at least one computer program, or use of the same. A computer program includes a sequence of instructions, executable in the digital processing device's CPU, written to perform a specified task. Computer readable instructions may be implemented as program modules, such as functions, objects, Application Programming Interfaces (APIs), data structures, and the like, that perform particular tasks or implement particular abstract data types. In light of the disclosure provided herein, those of skill in the art will recognize that a computer program may be written in various versions of various languages.
The functionality of the computer readable instructions may be combined or distributed as desired in various environments. In some embodiments, a computer program comprises one sequence of instructions. In some embodiments, a computer program comprises a plurality of sequences of instructions. In some embodiments, a computer program is provided from one location. In other embodiments, a computer program is provided from a plurality of locations. In various embodiments, a computer program includes one or more software modules. In various embodiments, a computer program includes, in part or in whole, one or more web applications, one or more mobile applications, one or more standalone applications, one or more web browser plug-ins, extensions, add-ins, or add-ons, or combinations thereof.
Referring now to
During operation of the vehicle equipped with the driveline of
System losses in a CVP equipped vehicle consist of the following: CVP efficiency losses, hydraulic pump losses, clutch energy losses, mode shift losses, torque converter losses, and engine losses (defined as deviation from best BSFC point), among others. Brake specific fuel consumption (BSFC) is a measure of the fuel efficiency of any prime mover that burns fuel and produces rotational, or shaft, power. It is typically used for comparing the efficiency of internal combustion engines with a shaft output. It is the rate of fuel consumption divided by the power produced. It may also be thought of as power-specific fuel consumption, for this reason. BSFC allows the fuel efficiency of different engines to be directly compared. Driver torque demand can be satisfied by an infinite combination of operating points consisting of a chosen engine operating point, CVP ratio, and mode selection. The required clamping load and line pressure requirements resulting from these choices further influences losses. Methods described herein will select system operating point that minimizes total system loss.
Methods disclosed herein can be implemented as an offline simulation tool that develops a set of calibration tables that define a rule based control strategy. Offline simulation tools can evaluate an infinite number of points as simulation time allows. Alternatively, methods can be implemented real time in a controller to dynamically optimize system operating points in vehicle. Real time execution would rely on a rule based table to choose a set of operating points in close proximity to offline simulation results at some arbitrary loop execution rate. In smaller increments of that loop rate each potential set of operating points is evaluated and the minimum loss point is selected.
Methods disclosed herein are executed as follows: For a given driver torque command the best BSFC operating point is chosen and system losses are calculated as a baseline. The control sub-system then generates alternative operating points that deviate from best BSFC operation point. System losses are calculated again and the operating point that minimizes total loss is selected.
Referring now to
Referring now to
Still referring to
Turning now to
Turning now to
Passing now to
Referring now to
Referring now to
Turning now to
Referring now to
Turning now to
Referring now to
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 CVP having a plurality of balls, each ball provided with a tiltable axis of rotation, each ball supported in a carrier assembly, the carrier assembly operably coupled to a shift actuator, the computer-implemented system comprising: a digital processing device comprising 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 comprising a software module configured to manage a plurality of vehicle driving conditions; a plurality of sensors configured to monitor vehicle parameters comprising: a transmission output shaft speed, an engine speed, an engine torque, a vehicle speed, a CVP ratio, and a commanded transmission output torque; wherein the software module is configured to execute instructions provided by an optimization sub-module, wherein the software module is adapted to determine a commanded CVP ratio based at least in part on the commanded transmission output torque.
In some embodiments of the computer-implemented system, the optimization sub-module further comprises a solution set generator, a sub-system loss model, and a total system loss sub-module.
In some embodiments of the computer-implemented system, the sub-system loss sub-module further comprises a CVP loss sub-system.
In some embodiments of the computer-implemented system, the sub-system loss sub-module further comprises an engine loss sub-system.
In some embodiments of the computer-implemented system, the sub-system loss sub-module further comprises a hydraulic pump loss sub-system.
In some embodiments of the computer-implemented system, the sub-system loss sub-module further comprises a torque converter loss sub-system.
In some embodiments of the computer-implemented system, the total system loss sub-module is configured to determine the minimum total loss from a set of operating conditions.
In some embodiments of the computer-implemented system, the set of operating conditions are determined in the solution set generator.
In some embodiments of the computer-implemented system, the solution set generator determines a set of operating conditions that satisfy the commanded transmission output torque.
In some embodiments of the computer-implemented system, the total system loss sub-module is configured to determine a commanded CVP ratio based at least in part on the minimum total loss.
In some embodiments of the computer-implemented system, the solution set generator is configured to determine a set of CVP ratio solutions based at least in part on the vehicle speed and the commanded transmission output torque.
In some embodiments of the computer-implemented system, the solution set generator is configured to determine a set of engine speed solutions and a set of engine torque solutions, wherein the set of engine speed solutions and the set of engine torque solutions are based at least in part on the set of CVP ratio solutions.
In some embodiments of the computer-implemented system, the total system loss sub-module further comprises a total loss minimization function.
In some embodiments of the computer-implemented system, the total loss minimization function is configured to execute a process, the process comprising the steps of: receiving a total loss set comprising an indexed array of solutions for total system loss; receiving an input power set comprising an indexed array of solutions for input power; comparing the input power set to a requested input power signal; and selecting a minimum total loss operating condition based at least in part on the comparison of the requested input power signal to the input power set.
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 inventions 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 of the invention. It will be appreciated, however, that no matter how detailed the foregoing appears in text, the invention can be 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 invention 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 invention with which that terminology is associated.
While preferred embodiments of the present invention 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 invention. It should be understood that various alternatives to the embodiments of the invention described herein are employable in practicing the invention. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.
The present application claims priority to U.S. Provisional Patent Application No. 62/249,810, filed Nov. 2, 2015, which is incorporated herein by reference in its entirety.
Number | Date | Country | |
---|---|---|---|
62249810 | Nov 2015 | US |