Patent Application
20190136969
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 may be implemented in a CVT may not be sufficient for some applications. A transmission may implement 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 may have multiple configurations that achieve the same final drive ratio.
The different transmission configurations can, 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 may be different for different applications of the same transmission. For example, the criteria for optimizing control of a transmission for fuel efficiency may 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 may differ depending on whether fuel efficiency or performance is being optimized.
Provided herein is a method for controlling ratio in a ball planetary variator (CVP) in a multiple mode transmission, said CVP operably coupled to an engine of a vehicle, the method including: sensing a commanded transmission mode; commanding a release of an off-going clutch based on the commanded transmission mode; commanding an engagement of an on-coming clutch based on the commanded transmission mode; calculating a torque capacity of the on-coming clutch; calculating a torque capacity of the off-going clutch; comparing the torque capacity of the on-coming clutch and the torque capacity of the off-going clutch; and commanding a CVP position correction when the torque capacity of the on-coming clutch is greater than the torque capacity of the off-going clutch.
Provided herein is a method for controlling ratio in a ball planetary variator (CVP) in a multiple mode transmission, said CVP operably coupled to an engine of a vehicle, the method including: sensing a commanded transmission mode; commanding a release of an off-going clutch based on the commanded transmission mode; commanding an engagement of an on-coming clutch based on the commanded transmission mode; determining an anticipated time to engagement of the on-coming clutch; and commanding a CVP position correction at a predetermined time based on the anticipated time to engagement of the off-coming clutch.
Provided herein is a method for controlling ratio in a ball planetary variator (CVP) in a multiple mode transmission, said CVP operably coupled to an engine of a vehicle, the method including: sensing an early commanded transmission mode, an on-going clutch speed, and an off-going clutch speed; commanding a release of an off-going clutch based on the early commanded transmission mode; commanding an engagement of an on-coming clutch based on the early commanded transmission mode; detecting a slip speed of the on-coming clutch; and commanding a CVP position correction based on the detection of a speed change in the on-coming clutch and the off-going clutch.
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.
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:
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 can be configured to receive input signals indicative of parameters associated with an engine coupled to the transmission. The parameters can include throttle position sensor values, vehicle speed, gear selector position, user-selectable mode configurations, and the like, or some combination thereof. The gear selector position is typically a PRNDL position. The electronic controller can also receive one or more control inputs. The electronic controller can determine an active mode and a variator ratio based on the input signals and control inputs. The electronic controller can control an overall transmission ratio of the variable ratio transmission by controlling one or more electronic actuators and/or hydraulic actuators such as 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 Ser. No. 14/425,842, entitled “3-Mode Front Wheel Drive And Rear Wheel Drive Continuously Variable Planetary Transmission” and, U.S. Patent Application 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, is optionally configured to control any of several types of variable ratio transmissions.
Provided herein are configurations of CVTs based on a ball type variators, sometimes referred to herein as a continuously variable planetary (“CVP”). Basic concepts of a ball type Continuously Variable Transmission 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 (first) traction ring 2, an output (second) traction ring 3, and an idler (sun) assembly 4 as shown on
The working principle of such a CVP of
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 substantially 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.
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 the 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 may 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 may be 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 may operate in both tractive and frictional applications. For example, in the embodiment where a CVT is used for a bicycle application, the CVT can operate at times as a friction drive and at other times as a traction drive, depending on the torque and speed conditions present during operation.
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 is optionally fueled by energy sources including hydrocarbon, electrical, biomass, 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. 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 the various illustrative logical blocks, modules, circuits, strategies, schemes, and algorithm steps described in connection with the embodiments disclosed herein, including with reference to the transmission control system described herein, for example, is optionally 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, strategies, schemes, 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, strategies, schemes, and circuits described in connection with the embodiments disclosed herein is optionally 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 is optionally a microprocessor, but in the alternative, the processor is optionally any conventional processor, controller, microcontroller, or state machine. A processor is also optionally 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 optionally 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. An exemplary storage medium is coupled to the processor such that the processor is capable of reading information from, and writing information to, the storage medium. In the alternative, the storage medium is optionally integral to the processor. The processor and the storage medium optionally 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
In some embodiments, a reverse clutch 16 is included in the multiple-mode gearing portion 13. The reverse clutch 16 is configured to provide a reverse mode of operation.
In some embodiments, the first clutch 14, the second clutch 15, and the reverse clutch 16 are hydraulically operated clutches.
In some embodiments, the first clutch 14, the second clutch 15, and the reverse clutch 16 are mechanically operated clutches.
In some embodiments, the transmission shifts from the first mode to the second mode when the slip speed of the on-going (or engaging) clutch is nearly equal to zero. This type of shift event, depicted on the graph of
To elucidate,
Turning now to
In some embodiments, the output signal processing module 106 is configured to transmit commanded signals to actuators based on target values determined in the transmission control module 104.
The transmission control module 104 optionally includes a variety of sub-modules or sub-routines for controlling continuously variable transmissions of the type discussed here. For example, the transmission control module 104 optionally includes a clutch control sub-module 108 that is programmed to execute control over clutches or similar devices within the transmission.
In some embodiments, the clutch control sub-module implements state machine control for the coordination of engagement of clutches or similar devices.
The transmission control module 104 optionally includes a CVP control sub-module 110 programmed to execute a variety of measurements and determine target operating conditions of the CVP, for example, of the ball-type continuously variable transmissions discussed here. It should be noted that the CVP control sub-module 110 optionally incorporates a number of sub-modules for performing measurements and control of the CVP. In some embodiments, the vehicle control system 100 includes an engine control module 112 configured to receive signals from the input signal processing module 102 and in communication with the output signal processing module 106. The engine control module 112 is configured to communicate with the transmission control module 104.
Referring now to
Referring now to
Referring now to
Referring now to
Turning now to
In some embodiments, the commanded CVP position correction determined through a calibrateable look-up table based on engine torque and CVP ratio. The control process 45 proceeds to a block 54 where commands are sent to complete the clutch shift.
Turning now to
In some embodiments, the signals optionally include a current transmission mode, a current CVP ratio, and an engine torque.
The control process 55 proceeds to an evaluation block 58. When the evaluation block 58 returns a false result, indicating that the mode shift has not been commanded by the transmission control module 104, the control process 55 returns to the block 57. When the evaluation block 58 returns a true result, indication that a mode shift has been commanded, the control process 55 proceeds to a block 59. The block 59 sends a command to initiate a shift of clutches. The control process 55 proceeds to a block 60 where an anticipated time to clutch engagement is determined.
In some embodiments, the block 60 is a trigger to start a timer based on clutch torque capacity or clutch pressure.
The control process 55 proceeds to a block 61 were a commanded CVP position correction is sent at a specified time in anticipation of the engagement of the on-coming clutch.
Referring now to
In some embodiments, the signals optionally include a current transmission mode, a current CVP ratio, and an engine torque.
The control process 65 proceeds to an evaluation block 68. When the evaluation block 68 returns a false result, indicating that an early command for a mode shift has not occurred, the control process 65 returns to the block 67. When the evaluation block 68 returns a true result, indicating that an early command for a mode shift has been issued, the control process 65 proceeds to a block 69 where commands are sent to initiate a release of the off-going clutch and an engagement of the on-coming clutch.
In some embodiments, an early mode shift command is a command to shift the clutches at a CVP ratio that is slightly lower than the synchronous ratio. For example, a synchronous ratio of the transmission 10 is 1.78, and an early mode shift command is optionally issued at a CVP ratio of 1.73. The control process 65 proceeds to a block 70 where a slip speed across the on-going clutch element is monitored, which indicates that a torque reversal has occurred, the control process 65 proceeds to a block 71. The block 71 sends a commanded CVP position correction.
The foregoing description details the preferred embodiments. 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 described herein may be employed 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.
This application claims priority to U.S. Provisional Application 62/582,975 filed on Nov. 8, 2017 which is hereby incorporated in by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62582975 | Nov 2017 | US |
