TRANSMISSION RELATED APPLICATIONS

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

Application No. 62/512,231 filed on May 30, 2017, and U.S. Provisional Patent Application No. 62/578,818 filed on October 30, 2017, which are incorporated herein by reference.

BACKGROUND

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 available to be implemented in a CVT are not 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 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 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 increased efficiency compared to other configurations providing the same final drive ratio.

SUMMARY

A method for controlling an electric hybrid vehicle having an engine, a first motor/generator, a second motor/generator, and a ball-planetary variator (CVP) provided with a ball in contact with a first traction ring assembly, a second traction ring assembly, and a sun assembly, the method including the steps of: receiving a plurality of signals representative of a CVP ratio, a vehicle speed, a motor/generator speed, and an engine speed; detecting a regenerative charging condition of the vehicle based on the vehicle speed; determining a target motor/generator speed or a target engine speed corresponding to a desired operating condition; determining a target CVP ratio based on the target motor/generator speed or the target engine speed; and commanding the CVP to operate at the target CVP ratio.

In some embodiments, the desired operating condition is a high power operating condition based on target motor/generator speed.

In some embodiments, the target CVP ratio is based on the target

motor/generator speed.

In some embodiments, the method further includes determining a target engine speed based on detecting a vehicle deceleration.

In some embodiments, the method further includes determining a target engine speed based on minimizing pumping losses in the engine.

In some embodiments, the desired operating condition is optimal motor efficiency is based on target motor/generator speed

In some embodiments, target CVP ratio is based on the target motor/generator speed.

In some embodiments, the method further includes determining a target engine speed for an optimal engine efficiency, wherein the target CVP ratio based on the target motor/generator speed and the target engine speed.

In some embodiments, the method further includes determining a target engine speed based on detecting a vehicle deceleration.

In some embodiments, the method further includes determining a target engine speed based on minimizing pumping losses in the engine.

In some embodiments, the desired operating condition is a lower engine pumping loss based on the target engine speed.

In some embodiments, the target CVP ratio is based on the target engine speed.

In some embodiments, the method further includes detecting a target engine speed based on detecting a vehicle deceleration.

In some embodiments, the method further includes detecting a target engine speed based on minimizing pumping losses in the engine.

In some embodiments, the plurality of signals include a brake pedal position signal. 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 devices 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 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 top level block diagram of the input/output interfaces to the hybrid supervisory controller.

Figure 5 is a schematic lever diagram depicting an electric hybrid powertrain having an engine, two motor/generators, and a ball-type variator.

Figure 6 is a flow chart of a braking control process implementable in the controller of Figure 4.

Figure 7 is an exemplary motor speed, torque, and power graph for the motor/generators of Figure 5.

Figure 8 is a schematic diagram depicting an electric hybrid powertrain having an engine, two motor/generators, and a ball-type variator.

Figure 9 is a flow chart of a regenerative mode control process for the electric hybrid powertrain of Figure 8.

Figure 10 is a schematic lever diagram depicting an electric hybrid powertrain having an engine, two motor/generators, and a ball-type variator.

Figure 11 is a flow chart of a regenerative mode control process for the electric hybrid powertrain of Figure 10. Figure 12 is a schematic lever diagram depicting an electric hybrid powertrain having an engine, two motor/generators, and a ball-type variator.

Figure 13 is a schematic lever diagram depicting an electric hybrid powertrain having an engine, two motor/generators, and a ball-type variator.

Figure 14 is a schematic lever diagram depicting system torques during negative power flow.

Figure 15 is a schematic lever diagram depicting system torque during positive power flow.

Figure 16 is a chart depicting regions of operation for the electric hybrid powertrains of Figures 12 and 13.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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, accelerator pedal position sensor values, vehicle speed, gear selector position, user-selectable mode configurations, and the like, or some combination thereof. The electronic controller can also receive one or more control inputs. The electronic controller can determine an active range and an active variator mode based on the input signals and control inputs. The electronic controller can 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 Number 14/425,842, entitled "3-Mode Front Wheel Drive And Rear Wheel Drive Continuously Variable Planetary Transmission" and, U.S. Patent Application Number 15/572288, 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 variator, also known as CVP, 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 contact with the balls, as input (first) traction ring assembly 2 and output (second) traction ring assembly 3, and an idler (sun) assembly 4 as shown on FIG. 1. In some embodiments, the output (second) traction ring assembly 3 includes an axial force generator mechanism. 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 substantially 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 adjustable 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 and second carrier members 6, 7 to impart a tilting of the axles 5 and thereby adjusts the speed ratio of the variator. Other types of ball CVTs also exist, like the one produced by Milner, but are slightly different.

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 (traction fluid) 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, as 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 herein are related to the control of a variator and/or a CVT using generally spherical planets each having a tiltable axis of rotation that is adjustable 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 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 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 the preferred 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.

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 can 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."

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 herein 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 canbe a microprocessor, but in the alternative, the processor can 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 can be integral to the processor. The processor and the storage medium could reside in an ASIC. For example, in some embodiments, a controller for use of control of the CVT includes a processor (not shown).

Referring now to FIG. 4, in some embodiments, control methods described herein are implementable in a hybrid supervisory controller 200 that is adapted to receive a plurality of input signals obtained from sensors equipped on an electric hybrid vehicle, and deliver a plurality of output signals to actuators and controllers provided on the vehicle. Illustrative examples of the hybrid supervisory controller 200 are described in Patent Cooperation Treaty Patent Application No. PCT/US 16/066766, which is hereby incorporated by reference. In some embodiments, the hybrid supervisory controller 200 is configured to receive signals from an accelerator pedal position sensor 210, a brake pedal position sensor 220, and a number of CVP sensors 230. The CVP sensors 230 optionally include input speed sensors, actuator position sensor, temperature sensors, and torque sensors, among others. The hybrid supervisory controller 200 receives a number of input signals from vehicle sensors 240. For example, the vehicle sensors 240 include, but are not limited to, battery state of charge (SOC), motor speed sensor, generator speed sensor, engine speed sensor, engine torque sensor, and a number of temperature sensors, among others.

The hybrid supervisory controller 200 performs a number of calculations based at least in part on the input signals to thereby generate the output signals. The output signals are received by a number of control modules equipped on the vehicle.

In some embodiments, the hybrid supervisory controller 200 is configured to communicate with a CVT control module 250, a motor/generator control module 260, a clutch actuator module 270, a brake control module 280, an engine control module 290, a battery management system (BMS) high voltage control module 300, a body control module 310, among other control modules 320 equipped on the vehicle.

It should be appreciated that the motor/generator/inverter control module 260 is optionally configured with a number of submodules to perform control functions for those components.

The hybrid supervisory controller 200 is adapted to be in communication with an accessory actuator module 330. In some embodiments, the hybrid supervisory controller 200 is optionally configured to communicate with a DC-DC inverter module 340 and a wall charger module 350, among other actuator control modules 360. It should be appreciated that the hybrid supervisory controller 200 is adapted to communicate with a number of vehicle controllers via CAN interface or direct electric connection.

In some embodiments, the hybrid supervisory controller 200 is adapted to interface with a typical electric grid configured to supply electrical energy from a source to a consumer.

In some embodiments, state of health (SOH) of a battery provides guidance as to how much energy overall can be stored in a battery pack. For example, the BMS high voltage module 300 monitors the SOC and SOH of the battery system and provides signals to the CVT control module 250.

The SOH of a new battery pack is 100%, but over time the amount of energy the battery pack can store decreases, for example, 85% of the original capacity.

In some embodiments, the SOC provides guidance as to how much energy can be accepted by the battery pack at the point of time it is evaluated. SOC represents how much energy is currently available in the battery pack.

By using the SOH and the SOC and other related battery pack management signals, the hybrid supervisory controller 200 is adapted to determine the optimal amount of energy to be directed to the battery pack.

Referring now to FIGS. 5-11, modern electric and electric hybrid vehicles are commonly configured to recuperate energy from the moving vehicle during

deceleration. The process of converting kinetic energy from the moving vehicle to potential energy in the battery system is sometimes referred to as "regenerative charging", "regenerative braking", or "energy recuperation". Control methods described herein incorporate a variator (CVP) to control operating conditions of components in the electric or electric hybrid vehicle to optimize the conversion of kinetic energy to potential energy.

For purposes of description, schematics referred to as lever diagrams are used herein. A lever diagram, also known as a lever analogy diagram, is a translational- system representation of rotating parts for a planetary gear system. In certain embodiments, a lever diagram is provided as a visual aid in describing the functions of the transmission. In a lever diagram, a compound planetary gear set is often

represented by a single vertical line ("lever"). The input, output, and reaction torques are represented by horizontal forces on the lever. The lever motion, relative to the reaction point, represents direction of rotational velocities. For example, a typical planetary gear set having a ring gear, a planet carrier, and a sun gear is represented by a vertical line having nodes "R" representing the ring gear, node "S" representing the sun gear, and node "C" representing the planet carrier.

Provided herein is control methods for optimizing powertrains of electric or electric-hybrid vehicles.

In some embodiments, the powertrain and/or drivetrain configurations use a ball planetary style continuously variable transmission to couple power sources used in a hybrid vehicle, for example, combustion engines (internal or external), motors, generators, batteries, and gearing. The powertrains disclosed herein are applicable to HEV, EV and Fuel Cell Hybrid systems. It should be understood that electric or hybrid electric vehicles incorporating embodiments of the hybrid architectures disclosed herein are capable of including a number of other powertrain components, such as, but not limited to, high-voltage battery pack with a battery management system or ultracapacitor, on-board charger, DC-DC converters, a variety of sensors, actuators, and controllers, among others.

It should be noted that the battery is capable of being not just a high voltage pack such as lithium ion or lead-acid batteries, but also ultracapacitors or other pneumatic/hydraulic systems such as accumulators, or other forms of energy storage systems.

Additionally the motor/generators described herein are capable of representing hydromotors actuated by variable displacement pumps, electric machines, or pneumatic motors driven by pneumatic pumps. The electric axle powertrain architectures depicted in the figures and described in text is capable of being extended to create a hydro- mechanical CVT architectures as well for hydraulic hybrid systems.

Turning now to FIG. 5, in some embodiments, an electric hybrid powertrain 20 includes an engine 21, a first motor/generator 22, a second motor/generator 23, and a ball-type variator (CVP) 24 similar to the variator described in Figures 1-3. The electric hybrid powertrain 20 has a planetary gear set 25 having a ring gear 26 operably coupled to the second motor/generator 23, a planet carrier 27 operably coupled to the engine 21, and a sun gear 28 operably coupled to the first motor/generator 21.

In some embodiments, the second motor/generator 23 is operably coupled to the CVP 24. The CVP 24 is configured to transmit an output power to a final drive gear 29. It should be appreciated that a variety of configuration for coupling the CVP 24 to the second motor/generator 23 are known. As illustrative example, electric hybrid powertrains are disclosed in United States Patent No. 15/760653; 15/760647; and 15/774625, which are hereby incorporated by reference.

Referring now to FIG. 6, in some embodiments, a braking control process 30. is adapted to control the electric hybrid powertrain 20 during a vehicle braking or coastdown maneuver. The braking control process 30 begins at a start state 31 and proceeds to a block 32 where a number of input signals are received. In some embodiments, the block 32 receives a vehicle speed signal, a brake pedal position signal, an engine speed signal, a first motor/generator speed signal, a second motor/generator speed signal, and a CVP ratio signal, among others. The braking control process 30 proceeds to an evaluation block 33 to assess the vehicle condition. If the evaluation block 33 returns a false result, indicating that the vehicle is not in a braking or coastdown condition, then the braking control process 30 returns to the block 32. If the evaluation block 33 returns a true result, indicating that the vehicle is performing a braking or coastdown maneuver, the braking control process 30 proceeds to a block 34. The block 34 determines a target motor speed for the second motor/generator 23 that corresponds to desired operating condition.

In some embodiments, the desired operation condition is a high power condition.

The braking control process 30 proceeds to a block 35 where a target CVP ratio for the CVP 24, for example, is determined based on the target motor speed from the block 34.

In some embodiments, the CVP ratio is a speed ratio.

In other embodiments, the CVP ratio is a torque ratio.

The braking control process 30 proceeds to a block 36 where a command is sent to control the CVP ratio to the target CVP ratio determined in the block 35. The braking control process 30 returns to the block 32.

Referring now to FIG. 7, when implemented, the braking control process 30 provides more efficient regenerative charging for the electric hybrid powertrain 20. The graph 40 depicted in Figure 7 is an exemplary motor performance chart as a function of speed. A motor torque 41 and a motor power 42 is depicted as a function of speed. During operation of the electric hybrid powertrain 20, the braking control process 30 is used to increase the speed of the second motor/generator 23 from a first speed 43 to a second speed 44, thereby increasing the power transmitted to the second motor/generator 23. During other operating conditions of the electric hybrid powertrain 20, the braking control process 30 is used to decrease the speed of the second motor/generator 23 from a first speed 45 to a second speed 46, thereby increasing the power transmitted to the second motor/generator 23.

Passing now to FIG. 8, in some embodiments, an electric hybrid powertrain 50 includes an engine 51 operably coupled to a variator (CVP) 52. The CVP 52 has a first traction ring assembly 52 that is operably coupled to a grounded member (not shown), a second traction ring assembly, a ball carrier 55 operably coupled to the engine 51, and a sun assembly 56 operably coupled to a first motor/generator 57. The second traction ring assembly 54 is operably coupled to a second motor/generator 58. It should be appreciated that electric hybrid powertrains disclosed herein are equipped with a charging system including a battery 59 and associated inverter/power electronics electrically coupled to the first motor/generator 57 and the second motor/generator 58.

Referring now to FIG. 9, during operation of the electric hybrid powertrain 50, a regenerative charging control process 60 is implemented to control the engine 51, the CVP 52, the first motor/generator 57, and the second motor/generator 58 to operate at optimal efficiency conditions. The regenerative charging control process 60 begins at a start state 61 and proceeds to a block 62 where a number of input signals are received.

In some embodiments, the block 62 receives a vehicle speed signal, a brake pedal position signal, an engine speed signal, a first motor/generator speed signal, a second motor/generator speed signal, and a CVP ratio signal, among others. The regenerative charging control process 60 proceeds to an evaluation block 63 where the operating condition of the electric hybrid powertrain 50 is assessed. If the evaluation block 63 returns a false result, indicating that the electric hybrid powertrain 50 is not in a regenerative charging operating condition, the regenerative charging control process 60 returns to the block 62. If the evaluation block 63 returns a true result, indicating that the electric hybrid powertrain 50 is in a regenerative charging condition, the regenerative charging process 60 proceeds to a block 64.

The block 64 determines a target motor speed for a desired operating condition. In some embodiments, the desired operating condition is optimal motor efficiency based on the operating condition of the vehicle.

In some embodiments, the target motor speed is determined for the first motor/generator 57.

In some embodiments, the target motor speed is determined for the second motor/generator 58. The regenerative charging control process 60 proceeds to a block 65 where a target engine speed for optimal efficiency of the engine 51 is determined based on the operating condition of the vehicle. The regenerative charging control process 60 proceeds to a block 66 where a target CVP ratio for the CVP 52 is determined based on the target motor speed and the target engine speed. The regenerative charging control process 60 proceeds to a block 67 where a command is sent to control the CVP 52 to the target CVP ratio. The regenerative charging control process 60 returns to the block 62.

It should be appreciated that the hybrid supervisory controller and the respective slave controllers control the operating conditions of the motor/generators.

Referring now to FIG. 10, in some embodiments, an electric hybrid powertrain 70 includes an engine 71, a first motor/generator 72, a second motor/generator 73, and a variator (CVP) 74. The electric hybrid powertrain 70 has a planetary gear set 75 having a ring gear 76 coupled to the second motor/generator 73, a planet carrier 77 operably coupled to the CVP 74, and a sun gear 78 operably coupled to the first motor/generator 72.

In some embodiments, the engine 71 is operably coupled to the CVP 74.

In some embodiments, the second motor/generator 73 is configured to transmit power out of the electric hybrid powertrain 70.

Turning now to FIG. 11, during operation of the electric hybrid powertrain 70, a regenerative charging control process 80 is implemented to control the engine 71 and the CVP 74 in coordination with the first motor/generator 72 and the second

motor/generator 73 to reduce the engine pumping losses and optimize the regenerative charging. The regenerative charging control process 80 begins at a start state 81 and proceeds to a block 82 where a number of input signals are received.

In some embodiments, the block 82 receives a vehicle speed signal, a brake pedal position signal, an engine speed signal, a first motor/generator speed signal, a second motor/generator speed signal, and a CVP ratio signal, among others. The regenerative charging control process 80 proceeds to an evaluation block 83 where the operating condition of the electric hybrid powertrain 70 is assessed. If the evaluation block 83 returns a false result, indicating that the electric hybrid powertrain 70 is not in a regenerative charging operating condition, the regenerative charging control process 80 returns to the block 82. If the evaluation block 83 returns a true result, indicating that the electric hybrid powertrain 70 is in a regenerative charging condition, the regenerative charging process 80 proceeds to a block 84. The block 84 determines a target engine speed for a desired operating condition.

In some embodiments, the desired operating condition is minimum pumping losses of the engine 71 on the operating condition of the vehicle. In some embodiments, the minimum pumping losses of the engine 71 are stored as calibrateable tables or maps based on engine speed and/or other engine operating conditions, for example, in memory.

The regenerative charging control process 80 proceeds to a block 85 where a target CVP ratio for the CVP 72 is determined based on the target engine speed. The regenerative charging control process 80 proceeds to a block 86 where a command is sent to control the CVP 72 to the target CVP ratio. The regenerative charging control process 80 returns to the block 62.

Referring now to FIG. 12, in some embodiments, an electric hybrid powertrain 90 includes an engine 91, a first motor/generator 92, a second motor/generator 93, and a ball-type variator (CVP) 98 similar to the variator described in Figures 1-3. The electric hybrid powertrain 90 has a planetary gear set 94 having a ring gear 95 operably coupled to the second motor/generator 93, a planet carrier 96 operably coupled to the engine 91, and a sun gear 97 operably coupled to the first motor/generator 92.

In some embodiments, the engine 91 is coupled to the planet carrier 96 through a one-way clutch 104.

In some embodiments, the second motor/generator 93 is operably coupled to the ring gear 95 with a transfer gear set 102.

The CVP 98 includes a first traction ring assembly 99, a second traction ring assembly 100, and a carrier assembly 101. The second motor/generator 93 is coupled to the first traction ring assembly 99. The CVP 24 is configured to transmit an output power to a final drive gear 103 through the second traction ring assembly 100. It should be appreciated that a variety of configurations for coupling the CVP 98 to the second motor/generator 93 are known.

Referring now to FIG. 13, embodiments, an electric hybrid powertrain 110 includes an engine 111, a first motor/generator 112, a second motor/generator 113, and a ball-type variator (CVP) 114 similar to the variator described in Figures 1-3. The CVP 114 includes a first traction ring assembly 115, a second traction ring assembly 116, and a carrier assembly 117. The electric hybrid powertrain 110 has a planetary gear set 119 having a ring gear 120 operably coupled to the second motor/generator 113, a planet carrier 121 operably coupled to the second traction ring assembly 116, and a sun gear 122 operably coupled to the first motor/generator 112. In some embodiments, the second motor/generator 113 is operably coupled to the ring gear 120 through a transfer gear set 123.

In some embodiments, the first traction ring assembly 115 is operably coupled to the engine 111 through a one-way clutch 118. The ring gear 120 is configured to transmit an output power to a final drive gear 124.

Turning now to FIGS. 14-16, in some embodiments, regeneration optimization in a power split hybrid, such as the electric hybrid powertrains depicted in FIG. 12 and FIG. 13, have a number of considerations to manage the ratio change of the CVP.

In some embodiments, the optimization factors in the capability for the battery pack to accept energy into the commanded ratio change of the CVP.

In some embodiment, for example, for the electric hybrid powertrain 20, the commanded CVP ratio is controlled to avoid conditions which lead to an increase in temperature that negatively impacts the battery pack's useful life. Those conditions include, but are not limited to, conditions having inefficient energy recuperation and charging of the battery pack and conditions having too much energy flowing to the battery pack.

In some embodiments, the aforementioned conditions are associated with extreme low CVP ratio or extreme high CVP.

In some embodiments, the sign of the first motor/generator speed must be consistent with the chart of Figure 16, as will be discussed herein, to stay in a generator mode.

In some embodiments, the magnitude of the first motor/generator speed must be such that regenerative power is optimized for a given electric machine efficiency map. FIG. 14 depicts the lever diagram of the planetary gear set 94 as illustrative example. As shown in FIG. 14, to operate in a regenerative breaking mode and have a negative power flow the engine torque (T _en g) is negative and torque of the first motor/generator (TMGI) is positive. Therefore, too operate in a generator mode, the first motor/generator speed must be negative.

It should be noted that when speed and torque of an electric motor are of opposite sign, the system is generating power whereas when speed and torque are of the same sign, the system is consuming power.

Similarly, FIG. 15 depicts the lever diagram of the planetary gear set 94 as illustrative example of a positive power flow while in motor mode. FIG. 16 is a chart 130 depicting operating regions of generator mode and motor mode for powersplit electric hybrid powertrains such as the ones depicted in FIGS. 12 and 13. The chart 130 has an x-axis 131 representing the speed of the first

motor/generator and a y-axis 132 representing the torque of the first motor/generator. A line 133 represents a maximum torque of the first motor/generator. A line 134 represents the minimum torque of the first motor/generator.

During operation of the powersplit electric hybrid powertrain, the CVP ratio is managed to hold the first motor/generator in the desired generator mode. It should be understood that a given vehicle speed and target engine speed, as well as adjustments in the CVP ratio, influence the motor/generator operating mode.

For a given vehicle speed, a target engine speed, and a CVP ratio moving towards an underdrive condition, the motor/generator speed will move towards negative, and with a positive torque command, the motor/generator will remain in generator mode.

For a given vehicle speed, a target engine speed, and a CVP repeating in an underdrive condition, a motor mode corresponds to a negative speed and negative torque of the first motor/generator.

For a given vehicle speed, a target engine speed, and a CVP ratio moving towards overdrive, the generator speed will move towards positive, and with a positive torque command, the motor/generator mode will tend to stay in motor mode.

For a given vehicle speed, a target engine speed, and a similar overdrive operating condition of the CVP, a generator mode corresponds to a positive speed and negative torque of the first motor/generator.

Under certain operating conditions, for a given vehicle speed, both the CVP ratio and the target engine speed are controlled to operate the first motor/generator in the generator mode.

In some operating conditions, the engine speed is increased to keep the first motor/generator in the desired generator mode.

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 preferred embodiments with which that terminology is associated.

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 preferred embodiments described herein could 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 additionally include the following.

Aspect 1. A vehicle comprising:

an engine;

a first motor/generator;

a second motor/generator;

a continuously variable planetary (CVP), wherein the CVP is a ball variator assembly having a sun assembly, 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 and wherein each tiltable axis is supported in a carrier assembly; and

a controller configured to detect a vehicle deceleration, the controller adapted to control a CVP ratio, an engine speed, a first motor/generator speed, and a second motor/generator speed,

wherein the controller commands a change in the CVP ratio to control the first motor/generator speed.

Aspect 2. The vehicle of Aspect 1, further comprising planetary gear set having a ring gear, a planet carrier, and a sun gear, wherein the planet carrier is operably coupled to the engine, the ring gear is coupled to the second motor/generator, and the sun gear is coupled to the first motor/generator.

Aspect 3. The vehicle of Aspect 2, wherein the CVP is operably coupled to the second motor/generator. Aspect 4. The vehicle of Aspect 3, wherein the controller is configured to determine a target motor/generator speed and adjust the CVP ratio to operate the second motor/generator at the target motor/generator speed.

Aspect 5. The vehicle of Aspect 1, wherein the engine is operably coupled to the carrier assembly of the CVP, the first traction ring assembly is non-rotatable, the first motor/generator is operably coupled to the sun assembly, and the second motor/generator is operably coupled to the second motor/generator.

Aspect 6. The vehicle of Aspect 5, wherein the controller determines a target engine speed based on detecting a vehicle deceleration.

Aspect 7. The vehicle of Aspect 1, further comprising planetary gear set having a ring gear, a planet carrier, and a sun gear, wherein the planet carrier is operably coupled to the CVP, the ring gear is coupled to the second motor/generator, the sun gear is coupled to the first motor/generator, and the engine is operably coupled to the CVP.

Aspect 8. The vehicle of Aspect 7, wherein the controller determines a target engine speed based on minimizing pumping losses in the engine.

Aspect 9. A computer-implemented method for controlling an electric hybrid vehicle having an engine, a first motor/generator, a second motor/generator, and a ball- planetary variator (CVP) provided with a ball in contact with a first traction ring assembly, a second traction ring assembly, a sun assembly, the method including the steps of: receiving a plurality of data signals provided by sensors located on the transmission, the plurality of data signals including: a CVP ratio, a vehicle speed, a motor/generator speed, and an engine speed; detecting a regenerative charging condition of the vehicle based on the vehicle speed; determining a target motor speed corresponding to a higher power operating condition; determining a target CVP ratio based on the target motor speed; and commanding the CVP to operate at the target CVP ratio.

Aspect 10. A computer-implemented method for controlling an electric hybrid vehicle having an engine, a first motor/generator, a second motor/generator, and a ball- planetary variator (CVP) provided with a ball in contact with a first traction ring assembly, a second traction ring assembly, a sun assembly, the method including the steps of: receiving a plurality of data signals provided by sensors located on the transmission, the plurality of data signals including: a CVP ratio, a vehicle speed, a motor/generator speed, and an engine speed; detecting a regenerative charging condition of the vehicle based on the vehicle speed; determining a target motor speed corresponding to an optimal motor efficiency; determining a target engine speed for an optimal engine efficiency; determining a target CVP ratio based on the target motor speed and the target engine speed; and commanding the CVP to operate at the target CVP ratio.

Aspect 11. A computer-implemented method for controlling an electric hybrid vehicle having an engine, a first motor/generator, a second motor/generator, and a ball- planetary variator (CVP) provided with a ball in contact with a first traction ring assembly, a second traction ring assembly, a sun assembly, the method including the steps of: receiving a plurality of data signals provided by sensors located on the transmission, the plurality of data signals including a CVP ratio, a vehicle speed, a motor/generator speed, and an engine speed; detecting a regenerative charging condition of the vehicle based on the vehicle speed; determining a target engine speed having a lower engine pumping loss; determining a target CVP ratio based on the target engine speed; and commanding the CVP to operate at the target CVP ratio.