Powertrain torque control system

Abstract

The present disclosure provides a "powertrain torque control system". A vehicle has an electric machine, a first axle shaft, a second axle shaft, a steering wheel, and a controller. The first axle shaft and the second axle shaft are configured to deliver torque from the electric machine to a first wheel and a second wheel, respectively. The controller is programmed to respond to (i) locking the first axle shaft to the second axle shaft, (ii) displacement of at least one of the first axle shaft and the second axle shaft or the steering wheel, and (iii) Commanding a torque of the electric machine to an expected value results in a torque distribution to the first and second axle shafts exceeding a torque capacity of at least one of the first and second axle shafts, the torque of the electric machine being truncated to less than the expected value.

Description

Technical Field

[0001] The present disclosure relates to a powertrain system for a vehicle. Background Art

[0002] A vehicle includes a powertrain configured to transfer power from a power generating device, such as an internal combustion engine or an electric machine, to drive wheels of the vehicle. Summary of the invention

[0003] A vehicle includes an electric motor, an axle, a locker, and a controller. The electric motor is configured to generate torque to propel the vehicle. The axle has a differential, and the differential is configured to receive torque from the electric motor. The axle has a first half shaft and a second half shaft, and the first half shaft and the second half shaft are configured to deliver torque from the differential to a first wheel and a second wheel, respectively. The steering wheel is configured to turn the first wheel and the second wheel. The locker is configured to activate to lock the differential so that the first half shaft and the second half shaft are constrained to rotate in unison. The locker is configured to deactivate to unlock the differential so that the first half shaft and the second half shaft are not constrained to rotate in unison. The controller is programmed to: in response to (i) activation of the lock, (ii) displacement of at least one of the first and second axles or the first and second wheels according to a set of conditions, and (iii) commanding the torque of the motor to a desired value causes the torque allocation to the first and second axles to exceed the torque capacity of at least one of the first and second axles, truncate the torque of the motor to less than a desired value so that the torque allocation to the first and second axles does not exceed the torque capacity of the first or second axles. The controller is also programmed to: in response to (i) deactivation of the lock, (ii) displacement of at least one of the first and second axles according to the set of conditions, and (iii) commanding the torque of the motor to the desired value, control the torque of the motor to the desired value.

[0004] A vehicle includes an electric machine, a first half-shaft, a second half-shaft, and a controller. The first half-shaft and the second half-shaft are configured to deliver torque from the electric machine to a first wheel and a second wheel, respectively. The controller is programmed to: in response to (i) locking the first half-shaft to the second half-shaft, (ii) displacement of at least one of the first half-shaft and the second half-shaft or the first wheel and the second wheel, and (iii) commanding the torque of the electric machine to a desired value results in the torque allocation to the first half-shaft and the second half-shaft exceeding the torque capacity of at least one of the first half-shaft and the second half-shaft, truncate the torque of the electric machine to less than the desired value so that the torque allocation to the first half-shaft and the second half-shaft does not exceed the torque capacity of the first half-shaft or the second half-shaft.

[0005] A vehicle includes an electric machine, a first half-shaft, a second half-shaft, and a controller. The first half-shaft and the second half-shaft are configured to deliver torque from the electric machine to a first wheel and a second wheel, respectively. The controller is programmed to: in response to (i) locking the first half-shaft to the second half-shaft, (ii) a difference between the twist of the first half-shaft and the twist of the second half-shaft exceeding a threshold, and (iii) commanding the torque of the electric machine to a desired value, truncate the torque of the electric machine to be less than the desired value. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is a schematic diagram showing a vehicle and a vehicle powertrain;

[0007] Figure 2 is a schematic diagram of the semi-axis shift angle;

[0008] FIG. 3A to FIG. 3C showing various positions of the wheels of the vehicle; and

[0009] Figure 4 is a flow chart illustrating a method for controlling the torque output of an electric machine. DETAILED DESCRIPTION

[0010] Embodiments of the present disclosure are described herein. However, it should be understood that the disclosed embodiments are merely examples and that other embodiments may take various and alternative forms. The drawings are not necessarily drawn to scale; some features may be enlarged or minimized to show the details of a particular component. Therefore, the specific structural details and functional details disclosed herein should not be interpreted as limiting, but only as a representative basis for teaching those skilled in the art to adopt the embodiments in different ways. As will be understood by those of ordinary skill in the art, the various features shown and described with reference to any one of the accompanying drawings may be combined with the features shown in one or more other drawings to produce embodiments that are not explicitly shown or described. The combination of features shown provides representative embodiments for typical applications. However, for specific applications or embodiments, various combinations and modifications of features consistent with the teachings of the present disclosure may be desired.

[0011] refer to Figure 1 , a schematic diagram representing a vehicle 10 and a corresponding powertrain 12 is shown. The powertrain 12 includes both a power generation component (i.e., an engine or an electric motor) and a drive train. The drive train is the group of components that deliver power to the drive wheels and does not include the power generation component. In contrast, a powertrain is considered to include both the power generation component and the drive train. The powertrain includes an electric machine 16. The electric machine 16 can be configured to draw power from a battery 18 and operate as an electric motor to generate power and torque in order to propel the vehicle 10. The electric machine 16 can also be configured to operate as a generator to charge the battery 18. For example, the electric machine 16 can operate as a generator to charge the battery 18 during a regenerative braking maneuver.

[0012] The motor 16 may be connected to the axle 20 through a series of drive train components. More specifically, the motor 16 may be connected to the differential 22 of the axle 20 through a drive shaft 24. The differential 22 may in turn be connected to the hub of the driving wheel or drive wheel 26 through a half shaft 28. The half shaft 28 may be referred to as a first half shaft and a second half shaft. There may be additional drive train connections between the motor 16 and the drive wheel 26. For example, a constant velocity joint 30 (see, e.g., Figure 2 ) can connect the output shaft or rotor shaft of the motor 16 to the drive shaft 24, connect the drive shaft 24 to the differential 22, connect the differential 22 to the half shaft 28, and / or connect the half shaft 28 to the hub of the drive wheel 26.

[0013] The differential 22 is configured to receive power and torque from the motor 16. The differential 22 is in turn configured to deliver the power and torque generated by the motor 16 to the half shafts 28. The half shafts 28 are then configured to deliver the power and torque generated by the motor 16 from the differential 22 to the drive wheels 26 to propel the vehicle 10. The drive wheels 26 may be referred to as first wheels and second wheels, and the first half shafts and the second half shafts may be configured to deliver the power and torque generated by the motor 16 from the differential 22 to the first wheels and the second wheels, respectively.

[0014] Figure 1 1 is shown as the front wheels of the vehicle 10. However, it should be understood that the drive wheels 26 may alternatively be the rear wheels of the vehicle 10. Furthermore, while the motor 16 is shown as being the power generating component of the powertrain 12, other power generating components (i.e., an internal combustion engine or a fuel cell) may also be used in place of or in addition to the motor 16 (such as of a hybrid vehicle).

[0015] It should be understood that the vehicle configurations described herein are exemplary only and are not intended to be limiting. Other non-hybrid, electric, or hybrid vehicle configurations should be construed as disclosed herein. Other vehicle configurations may include, but are not limited to, micro-hybrid vehicles, series hybrid vehicles, parallel hybrid vehicles, series-parallel hybrid vehicles, plug-in hybrid electric vehicles (PHEVs), fuel cell hybrid vehicles, battery-operated electric vehicles (BEVs), or any other vehicle configuration known to those of ordinary skill in the art.

[0016] The operator of the vehicle 10 can control the speed of the vehicle and / or the torque applied at the drive wheels 26 of the vehicle 10 by depressing the accelerator pedal 32 or the brake pedal 34. Depressing the accelerator pedal 32 can be consistent with a request to increase the vehicle speed and / or torque. Depressing the brake pedal 34 can be consistent with a request to decrease the vehicle speed and / or torque. Depressing the accelerator pedal 32 or the brake pedal 34 can send an acceleration request or a braking request, respectively, to the vehicle controller 36. The vehicle controller 36 can then adjust the power, speed and / or torque of the electric machine 16, or adjust the torque applied to the friction brake 38 based on the acceleration or braking request and the current vehicle speed.

[0017] The vehicle 10 may also include a steering system 42 configured to turn the wheels 26 to a desired steering angle θ based on user input received from a steering wheel 44. st The steering wheel sensor 46 may be configured to shift the current angle of the steering wheel 44 by θ sw (which may also be referred to as the steering wheel angle) is transmitted to the controller 36. The current angular displacement θ of the steering wheel 44 swThe angular displacement and angular velocity in the clockwise or counterclockwise direction, respectively, may be included. The angular displacement θ of the steering wheel 44 sw The value of can correspond to the steering angle θ st For example, the angular displacement θ of the steering wheel 44 sw With steering angle θ st There may be a linear relationship between θ and θ. This relationship may be stored by the controller 36 so that the controller 36 may shift the angle of the steering wheel 44 by θ sw The value is converted to the steering angle θ st Alternatively, an additional sensor may be provided on the wheel 26, which measures the steering angle θ st Transmitted to the controller 36.

[0018] The differential 22 may be an electronically controlled differential. The differential 22 may include a locker or locking clutch 52. The locking clutch 52 may be a variable torque capacity locking clutch configured to reduce the relative speed of the relative wheels 26 on the axle 20 as the locking clutch torque increases. The torque of the locking clutch 52 may be adjusted between a fully disengaged condition and a fully locked condition, including a slipping condition between the fully disengaged condition and the fully locked condition. As the torque on the locking clutch 52 increases during the slipping condition, the relative speed of the corresponding relative wheels 26 on the relative half shaft 28 and the axle 20 will decrease. When the locking clutch 52 obtains a torque sufficient to lock the differential 22, the speeds of the relative half shaft 28 and the corresponding relative wheels 26 become synchronized, and the relative speed between the relative wheels 26 becomes zero. The differential 22 may include an actuator 54 configured to engage / disengage the locking clutch 52 by increasing or decreasing the torque acting on the locking clutch 52. The actuator 54 can receive a signal from the controller to increase or decrease the torque on the locking clutch 52. The actuator 54 can be an electric solenoid, a hydraulic valve, or any other device known in the art that can increase and decrease the torque on the clutch. The actuator 54 can also act as a sensor that transmits the amount of torque acting on the locking clutch 52 back to the controller 36. The operator can engage the control panel and transition the locking clutch 52 between a locked condition, an unlocked condition, and a slipping condition.

[0019] The locking clutch 52 is not limited to the clutch types disclosed herein, but can be any type of differential locking clutch or locker known in the art. For example, a locker that locks or unlocks the differential 22 can be utilized. Such a locker can be configured to be activated to lock the differential 22 so that the opposing half-shafts 28 and the corresponding opposing wheels 26 are constrained to rotate in unison, and deactivated to unlock the differential 22 so that the opposing half-shafts 28 and the corresponding opposing wheels 26 are not constrained to rotate in unison.

[0020] Although shown as one controller, the controller 36 may be part of a larger control system and may be controlled by various other controllers throughout the vehicle 10, such as a vehicle system controller (VSC). It should therefore be understood that the controller 36 and one or more other controllers may be collectively referred to as a "controller" that controls various actuators in response to signals from various sensors to control the functions of the vehicle 10 or vehicle subsystems. The controller 36 may include a microprocessor or central processing unit (CPU) that communicates with various types of computer-readable storage devices or media. The computer-readable storage devices or media may include, for example, volatile and non-volatile storage devices in read-only memory (ROM), random access memory (RAM), and keep-alive memory (KAM). KAM is a persistent or non-volatile memory that can be used to store various operating variables when the CPU is powered off. The computer readable storage device or medium may be implemented using any of a number of known memory devices, such as a PROM (programmable read-only memory), an EPROM (electrical PROM), an EEPROM (electrically erasable PROM), flash memory, or any other electrical, magnetic, optical, or combination memory device capable of storing data, some of which represent executable instructions used by the controller 36 to control the vehicle 10 or a vehicle subsystem.

[0021] The control logic, algorithm or function executed by the controller 36 can be represented by a flowchart or similar diagram in one or more of the accompanying drawings. These drawings provide representative control strategies and / or logic that can be implemented using one or more processing strategies (such as event-driven, interrupt-driven, multi-tasking, multi-threading, etc.). Thus, the various steps or functions shown can be performed in the order shown, can be performed in parallel, or can be omitted in some cases. Although not always explicitly shown, it will be recognized by those of ordinary skill in the art that one or more of the steps or functions shown can be repeatedly performed according to the specific processing strategy used. Similarly, the processing order is not necessarily required to achieve the features and advantages described herein, but is provided for ease of illustration and description. The control logic can be implemented primarily in software executed by a microprocessor-based vehicle, engine and / or powertrain controller. Of course, depending on the specific application, the control logic can be implemented in one or more controllers in software, hardware, or a combination of software and hardware. When implemented in software, the control logic can be provided in one or more computer-readable storage devices or media, which store data representing codes or instructions executed by a computer to control a vehicle or a vehicle subsystem. The computer-readable storage device or medium may include one or more of several known physical devices that utilize electrical, magnetic, and / or optical storage to hold executable instructions and associated calibration information, operating variables, and the like.

[0022] The controller 36 may be configured to receive the Figure 1 10. The electrical signals may be delivered to the controller 36 from the various components via the input channels. In addition, the electrical signals received from the various components may indicate a request or command to change or alter the state of one or more of the corresponding components of the vehicle 10. The controller 36 includes an output channel that is configured to deliver (via electrical signals) the request or command to the various vehicle components. The controller 36 includes control logic and / or algorithms that are configured to generate the request or command delivered via the output channel based on the request, command, condition or status of the various vehicle components.

[0023] Input channels and output channels are Figure 1 It should be understood that a single dotted line may represent both an input channel and an output channel entering or leaving a single element. In addition, an output channel entering one element may operate as an input channel leading to another element, and vice versa.

[0024] refer to Figure 2 , showing one side of the axle 20. It should be understood that the corresponding components on the other side of the axle 20 may be Figure 2 . The displacement of the wheel 26 relative to the neutral position can be determined by measuring the half-shaft angle Φ of the corresponding half-shaft 28 relative to the horizontal plane. An increase in the half-shaft angle Φ relative to the neutral position indicates that the corresponding wheel 26 is in a droop condition, while a decrease in the half-shaft angle Φ relative to the neutral position indicates that the corresponding wheel 26 is in a hop condition. The ride height sensor 56 can communicate the amount of droop or hop that each wheel 26 is experiencing to the controller 36.

[0025] refer to FIG. 3A to FIG. 3C , various positions of the wheels 26 of the vehicle 10 are shown. Each wheel 26 may be connected to a suspension system including a shock absorber or strut 62 and / or a spring 64. The springs 64, along with a portion of the weight of the vehicle 10 experienced at each wheel 26, are intended to maintain the wheel in a neutral or home position (e.g., a position in which the weight of the vehicle and the load on the springs 64 balance such that the position of the wheel 26 remains stationary). Figure 3A A neutral or home position is shown in , wherein the wheels 26 rest on a flat surface 66 .

[0026] When the wheel 26 encounters a deviation from the flat surface 66 (such as a bump 68) (e.g., Figure 3B), the wheel 26 moves upward, energy is absorbed by the strut 62 and stored in the spring 64. When the wheel 26 has passed the deflection that caused the upward movement, the energy stored in the spring 64 and the portion of the weight of the vehicle 10 experienced at the wheel 26 return the wheel 26 to the neutral or home position. This return to the neutral or home position may be referred to as rebound. The upward deflection from the neutral or home position may be referenced by the distance the wheel 26 travels upward from the neutral or home position, which is referred to as upjump.

[0027] When the wheel 26 encounters a deviation from the flat surface 66 (such as a depression 70) (e.g., Figure 3C ), the wheel 26 moves downward, energy is absorbed by the strut 62 and the preload energy from the weight of the vehicle 10 is released from the spring 64. When the wheel 26 has passed the deflection that caused the downward movement, the weight of the vehicle 10 experienced at the wheel 26 reloads the spring 64 and returns the wheel 26 to the neutral or home position. The downward deflection from the neutral or home position can be referenced by the distance the wheel 26 travels downward from the neutral or home position, which is referred to as droop.

[0028] The amount of jump or sag can be determined by a sensor 56 such as a ride height sensor (see Figure 1 ) measurements, which determine the relative travel (jump or sag) of the wheel 26 from the neutral or home position. The sensor 56 can then transmit the relative travel of the wheel 26 to the controller 50. More specifically, the sensor 56 can be fixed to the strut 62 or spring 64, and can measure the distance traveled by the strut 62 and / or spring 64 from the neutral or home position to determine the relative travel of the wheel 26 from the neutral or home position. Additionally or alternatively, the load that each wheel 26 is experiencing can be derived from the pitch rate, roll rate, and / or yaw rate that can be measured by one or more sensors, and then transmitted to the controller 50. More specifically, the one or more sensors can be accelerometers, and the load that each wheel 26 is experiencing can be related to the distance traveled from the neutral or home position. This relationship between the load at each wheel and the distance traveled from the neutral or home position can be a linear relationship. For example, the travel distance from the neutral or home position may be equal to the product of (i) the spring constant of spring 64 and (ii) the difference between the current load on wheel 26 and the load on wheel 26 when in the neutral or home position.

[0029] The amount of torque generated by the motor 16 may be less than the amount of torque that the two half-shafts 28 can handle together, but greater than the amount of torque that a single half-shaft 28 can handle alone. When the differential locker is closed (e.g., when the locking clutch 52 is disengaged), the torque distribution at the differential 22 is approximately 50% / 50% between the two half-shafts 28, which will eliminate the possibility of the following scenario: the load of a single half-shaft 28 may exceed the amount of torque that a single half-shaft 28 can handle. When the differential locker is on (e.g., when the locking clutch 52 is closed and locked), up to 100% of the torque can be transferred to one of the half-shafts 28. This will be slip-limited. However, if one wheel 26 is in the air, the normal force on the other grounded wheel 26 may be doubled, making it potentially susceptible to the following scenario: the load of a single half-shaft 28 may exceed the amount of torque that a single half-shaft 28 can handle.

[0030] The data indicates that events of loading one axle 28 with more than 75% of maximum capacity are rare, likely due to the severity of the event and driver caution. However, it may be important to attempt to detect and compensate for such events to protect the integrity of the axle 28. Such a strategy may overly aggressively cut torque when the vehicle operator may need the full capacity of the motor 16 to get out of trouble or over an obstacle.

[0031] A ride height sensor (e.g., sensor 56) can be used to determine the normal force on each wheel 26, thereby allowing the overload susceptibility of the half-shaft 28 to be determined. With the locker on (e.g., when the locking clutch 52 is closed and locked), torque may be cut off when one wheel 26 is in full hop. However, this may result in excessive and / or abrupt torque cutoff. Therefore, the strategy described herein determines the deflection of both wheels 26, calculates the potential torque that can be absorbed by the higher loaded wheel 26, and cuts off (e.g., reduces) the torque if the potential torque that can be absorbed by the higher loaded wheel 26 is higher than the amount of torque that a single half-shaft 28 can withstand. The strategy may also take into account the torque that can be absorbed by a less loaded but still loaded wheel 26 (e.g., a hopped wheel) to minimize drive torque losses. Additionally, the strategy may provide a torque cutoff based on the compound angle of each half-shaft 28 (e.g., steering angle θ stThe strategy may be to reduce the torque of the motor 16 when the lock is on (e.g., when the lockup clutch 52 is closed and locked), and then increase the torque when the normal force load on the wheel 26 is within an acceptable range. The normal force may be determined via the ride height sensor 56 and may be supplemented by calculations based on the physics of the suspension and sprung mass. This may provide additional confidence that the half-shaft 28 is not inadvertently placed in an over-torque scenario.

[0032] Comparison of changes in motor speed to changes in wheel speed provides a direct measure of rotational deflection (e.g., twist) of the axle shaft 28. Alternatively, comparison between changes in speed of each wheel 26 on the axle 20 can provide a measure of rotational deflection (e.g., twist) of the axle shaft 28. Sensors can measure the speed of the motor 16 and the wheels 26, and can transmit the speeds to the controller 36. Such sensors can include a rotary transformer at the motor 16 and an ABS tone ring at the wheel 26. Such sensors can be provided by Figure 1 The sensors 56 in FIG. 5A and 5B are collectively represented. Large and particularly unequal (right wheel 26 and left wheel 26) levels of rotation (e.g., twist) indicate a high level of load. Rotational deflection (e.g., twist) can be used to provide increased confidence that one wheel 26 cannot absorb torque and the other wheel 26 load is high when the lock is on (e.g., when the lockup clutch 52 is closed and locked). Therefore, when the suspension data (e.g., the steering angle θ st When the rotational deflection (e.g., twisting) is not available, the suspension displacement method (i.e., according to the steering angle θ) can be supplemented. st and the half-shaft angle Φ to calculate the potential torque that can be absorbed by the higher-loaded wheel 26) or as an alternative approach.

[0033] refer to Figure 4 , a flow chart of a method 100 for controlling the torque output of the electric machine 16 is shown. The method 100 may be stored as control logic and / or an algorithm within one or more of the vehicle controllers (e.g., the controller 36). The method 100 is initiated at box 102. The start box 102 may correspond to an engagement or "key-on" condition of the vehicle ignition indicating that an operator is initiating a new drive cycle for operating the vehicle.

[0034] The method 100 then proceeds to box 104 where it is determined whether a torque command has been generated (e.g., the operator of the vehicle 10 has depressed the accelerator pedal 32 to generate a desired torque command to propel the vehicle 10). If a torque command has not been generated, the method 100 loops back to the beginning of box 104. If a torque command has been generated, the method 100 proceeds to box 106.

[0035] At frame 106, it is determined whether the differential locker has been activated such that the differential 22 is locked (e.g., the locking clutch 52 is activated and the differential 22 is locked such that the first and second half shafts 28 and the corresponding wheels 26 are constrained to rotate in unison). If the differential locker has not been activated (e.g., the locking clutch 52 has not been activated and the differential 22 is disengaged and not locked), the method 100 proceeds to frame 108, where the electric machine 16 (or other prime mover) is operated at the desired torque command to propel the vehicle 10. If the differential locker has been activated (e.g., the locking clutch 52 has been activated and the differential 22 is locked), the method 100 proceeds to frame 110.

[0036] At box 110, the torque capacity of each half-shaft 28 is determined based on the deflection or displacement of each half-shaft 28. The torque capacity may refer to the amount of torque that can be transmitted to the wheel 26 via the half-shaft 28, wherein the torque is transmitted through the wheel 26 without slipping between the wheel 26 and the surface on which the wheel 26 travels. The torque capacity of the half-shaft 28 to transmit torque is not always consistent with the torque upper limit or torque capacity of the half-shaft 28 to transmit torque. The torque upper limit or torque capacity of the half-shaft 28 may correspond to the mechanical upper limit or ability of the half-shaft 28 to transmit torque. The purpose of the system described herein is to protect the half-shaft 28 in a scenario where the torque capacity of at least one of the half-shafts 28 exceeds the torque upper limit or torque capacity of the half-shaft 28. This scenario may occur when one of the wheels 26 is in a drooping condition and the other of the wheels 26 is not in a drooping condition (e.g., the other of the wheels 26 is in a neutral or jump-up condition), and a large torque is delivered to the axle including the two half-shafts 28. Other scenarios may include a large amount of twisting within the half-shaft 28.

[0037] The torque capacity of each axle 28 may be stored in a lookup table within the controller 36 and may be based on or may be a function of: (i) the normal force applied to the corresponding wheel 26 connected to the corresponding axle 28; (ii) the radius of the corresponding wheel 26; (iii) the coefficient of friction (Mu) between the corresponding wheel 26 and the surface on which the corresponding wheel 26 travels; and (iv) the steering angle θ of the vehicle 10. st The normal force applied to each wheel 26 may be derived from the position of a ride height sensor (eg, sensor 56 ) coupled to each wheel 26 .

[0038] The ride height sensor can also determine the half-shaft angle Φ of the corresponding half-shaft 28 connected to each wheel 26. The half-shaft angle Φ of the corresponding half-shaft 28 and the steering angle θ of the vehicle 10 can be determined based on the half-shaft angle Φ of the corresponding half-shaft 28 and the steering angle θ of the vehicle 10. st The compound angle at each half-shaft 28 is determined by summing the half-shaft angle Φ of the corresponding half-shaft 28 and the steering angle θ of the vehicle 10. The torque capacity of each half-shaft 28 may also or alternatively be stored in a lookup table within the controller 36 and may be based on or may be a function of the compound angle at each half-shaft 28, which is based on the half-shaft angle Φ of the corresponding half-shaft 28 and the steering angle θ of the vehicle 10. st The sum of .

[0039] Next, the method 100 advances to frame 112, where it is determined whether the torque distribution to the half-shafts 28 will exceed the torque upper limit or torque capacity of at least one of the half-shafts 28 based on the desired torque command for propelling the vehicle 10. The torque distribution to the half-shafts 28 may exceed the torque upper limit or torque capacity of one of the half-shafts 28 in the following scenarios: (i) the differential locker has been activated so that the differential 22 is locked; (ii) the torque capacity of the first of the half-shafts 28 determined at frame 110 exceeds the torque upper limit or torque capacity of the first of the half-shafts 28; and (iii) the desired torque command for propelling the vehicle 10 will result in the torque delivered to the first of the half-shafts 28 exceeding the torque upper limit or torque capacity of the first of the half-shafts 28. Such a scenario may consider delivering torque to the second of the half-shafts 28 at the torque capacity of the second of the half-shafts 28 determined at frame 110.

[0040] It should also be noted that when certain scenarios exist, at box 112, the torque distribution to the half-shafts 28 may exceed the torque limit or torque capacity of one of the half-shafts 28. Such scenarios may correspond to scenarios where the deflection or displacement of the half-shaft 28 or wheel 26 determined at box 110 is within a first set of conditions or parameters. Such a first set of conditions or parameters may include: (i) a compound angle (e.g., one of the half-shaft angles Φ and the steering angle θ of the vehicle 10) st or (ii) a drooping condition of one of the wheels 26 and a neutral or jumping condition of another of the wheels 26.

[0041] On the other hand, when certain other scenarios exist, at box 112, the torque distribution to the half-shafts 28 may not exceed the torque upper limit or torque capacity of one of the half-shafts 28. Such other scenarios may correspond to scenarios where the deflection or displacement of the half-shaft 28 or wheel 26 determined at box 110 is within a second set of conditions or parameters. Such a second set of conditions or parameters may include: (i) a compound angle (e.g., one of the half-shaft angles Φ and the steering angle θ of the vehicle 10) st The sum of the values ​​of the two wheels 26 does not exceed or is less than a threshold value; or (ii) the two wheels 26 are in a neutral or jumping condition.

[0042] If the answer at box 112 is no, the method 100 proceeds to box 108. If the answer at box 112 is yes, the method 100 proceeds to box 112 where the torque of the electric machine 16 (or other prime mover) is truncated to less than a desired value so that the torque distribution to the half-shafts 28 does not exceed the torque limit or torque capacity of any of the half-shafts 28. It should be noted that if the differential locker is not activated at box 106, the method 100 can proceed to box 108 regardless of any deflection or displacement of the half-shafts 28 and / or wheels 26.

[0043] In an alternative configuration, blocks 110 and 112 may be eliminated and replaced by a single block that determines whether the difference between the twist of the first of the axle shafts 28 and the twist of the second of the axle shafts 28 exceeds a threshold value. In response to a "yes" answer at block 106, the method 100 will proceed to such a block that replaces blocks 110 and 112. If the difference between the twist of the first of the axle shafts 28 and the twist of the second of the axle shafts 28 does not exceed the threshold value, the method will proceed to block 108. If the difference between the twist of the first of the axle shafts 28 and the twist of the second of the axle shafts 28 does not exceed the threshold value, the method will proceed to block 114. The twist can be measured by comparing the change in speed of the motor (which can be measured and transmitted to the controller 36 via a sensor such as a resolver) relative to the change in speed of the wheel 26 (which can be measured and transmitted to the controller 36 via a sensor such as an ABS sensor), which will provide a direct measure of the deflection of the axle shaft 28. This alternative can be used to provide an increased confidence that one wheel 26 cannot absorb torque and the other wheel 26 load is high when the differential locker has been activated. This alternative can supplement or be used in place of the suspension shifting method, particularly when no suspension data (e.g., the deflection or displacement of the half-shaft 28 and wheel 26 determined at box 110) is available. In a similar manner, the degree of twist can be used to more directly calculate the torque absorbed at each axle, allowing the system to still protect the highly loaded axle while not truncating torque that can be easily absorbed by the less loaded axle.

[0044] It should be understood that Figure 4 The flowchart in FIG. 1 is for illustrative purposes only, and method 100 should not be construed as limiting Figure 4 Some of the steps of method 100 may be rearranged, while other steps may be omitted entirely.

[0045] It should be understood that the first, second, third, fourth, etc. labels for any components, states or conditions described herein can be rearranged in the claims so that they are arranged in chronological order with respect to the claims. In addition, it should be understood that if one or more specific components, states or conditions are claimed, any components, states or conditions described herein without a numerical designation can be given a first, second, third, fourth, etc. designation in the claims.

[0046] The words used in the specification are descriptive rather than restrictive, and it should be understood that various changes may be made without departing from the spirit and scope of the present disclosure. As previously mentioned, the features of the various embodiments may be combined to form additional embodiments that may not be explicitly described or shown. Although various embodiments may have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, it should be recognized by those of ordinary skill in the art that one or more features or characteristics may be compromised to achieve the desired overall system properties, depending on the specific application and implementation. To this end, embodiments that are described as being less desirable than other embodiments or prior art implementations with respect to one or more characteristics are within the scope of the present disclosure and may be desirable for a particular application.

[0047] According to the present invention, a vehicle is provided, which has: an electric motor, the electric motor is configured to generate torque to propel the vehicle; an axle, the axle having (i) a differential, the differential is configured to receive torque from the electric motor; and (ii) a first half shaft and a second half shaft, the first half shaft and the second half shaft are configured to deliver torque from the differential to a first wheel and a second wheel, respectively; a locker, the locker is configured to (i) activate to lock the differential so that the first half shaft and the second half shaft are constrained to rotate in unison, and (ii) deactivate to unlock the differential so that the first half shaft and the second half shaft are not constrained to rotate in unison; and a controller, the controller being programmed to respond to (i) activation of the locker, (ii) activation of the first half shaft and The second half-shaft or at least one of the first and second wheels is shifted according to a set of conditions and (iii) the torque of the motor is commanded to an expected value, resulting in the torque allocation to the first half-shaft and the second half-shaft exceeding the torque capacity of at least one of the first half-shaft and the second half-shaft, the torque of the motor is truncated to be less than the expected value, so that the torque allocation to the first half-shaft and the second half-shaft does not exceed the torque capacity of the first half-shaft or the second half-shaft; and in response to (i) deactivation of the lock, (ii) shifting of at least one of the first half-shaft and the second half-shaft according to the set of conditions and (iii) the torque of the motor is commanded to the expected value, the torque of the motor is controlled to the expected value.

[0048] According to an embodiment, the set of conditions includes a compound angle exceeding a threshold, and wherein the compound angle includes the sum of an angle of at least one of the first and second half-shafts and a steering angle of the first and second wheels.

[0049] According to an embodiment, the set of conditions includes: (i) a droop condition of one of the first wheel and the second wheel; and (ii) a neutral or hop-up condition of the other of the first wheel and the second wheel.

[0050] According to an embodiment, the controller is also programmed to: control the torque of the motor to the desired value in response to (i) activation of the lock, (ii) shifting of at least one of the first half-shaft and the second half-shaft or the first wheel and the second wheel according to a second set of conditions, and (iii) commanding the torque of the motor to the desired value resulting in the torque allocation to the first half-shaft and the second half-shaft not exceeding the torque capacity of the first half-shaft or the second half-shaft.

[0051] According to an embodiment, the second set of conditions comprises a compound angle being less than a threshold, and wherein the compound angle comprises the sum of an angle of at least one of the first and second half-shafts and a steering angle of the first and second wheels.

[0052] According to an embodiment, the second group of conditions includes: neutral or jump-on conditions of the first wheel and the second wheel.

[0053] According to an embodiment, the controller is further programmed to: in response to (i) activation of the lock, (ii) a difference between the twist of the first half-shaft and the twist of the second half-shaft exceeding a threshold, and (iii) commanding the torque of the motor to be the desired value, truncate the torque of the motor to be less than the desired value.

[0054] According to the present invention, a vehicle is provided, the vehicle having: a motor; a first half-shaft and a second half-shaft, the first half-shaft and the second half-shaft being configured to deliver torque from the motor to a first wheel and a second wheel, respectively; and a controller, the controller being programmed to truncate the torque of the motor to less than the expected value in response to (i) locking the first half-shaft to the second half-shaft, (ii) shifting of at least one of the first half-shaft and the second half-shaft or the first wheel and the second wheel, and (iii) commanding the torque of the motor to a desired value resulting in the torque allocation to the first half-shaft and the second half-shaft exceeding the torque capacity of at least one of the first half-shaft and the second half-shaft.

[0055] According to an embodiment, the controller is also programmed to: control the torque of the motor to the desired value in response to (i) unlocking the first half-shaft from the second half-shaft, (ii) shifting at least one of the first half-shaft and the second half-shaft or the first wheel and the second wheel, and (iii) commanding the torque of the motor to be the desired value.

[0056] According to an embodiment, the displacement of at least one of the first and second half-shafts or the first and second wheels corresponds to a compound angle exceeding a threshold, and wherein the compound angle comprises the sum of the angle of at least one of the first and second half-shafts and the steering angles of the first and second wheels.

[0057] According to an embodiment, the displacement of at least one of the first and second half-axles or the first and second wheels corresponds to: (i) a drooping condition of one of the first and second wheels; and (ii) a neutral or jumping condition of the other of the first and second wheels.

[0058] According to an embodiment, the controller is also programmed to: control the torque of the motor to the desired value in response to (i) locking the first half-shaft to the second half-shaft, (ii) a second shift of at least one of the first half-shaft and the second half-shaft or the first wheel and the second wheel, and (iii) commanding the torque of the motor to the desired value so that the torque distribution to the first half-shaft and the second half-shaft does not exceed the torque capacity of the first half-shaft or the second half-shaft.

[0059] According to an embodiment, the second displacement of at least one of the first and second axles or the first and second wheels corresponds to a compound angle less than a threshold, and wherein the compound angle comprises the sum of the angle of at least one of the first and second axles and the steering angles of the first and second wheels.

[0060] According to an embodiment, the second displacement of at least one of the first and second axle shafts corresponds to a neutral or a hop-up condition of the first and second wheels.

[0061] According to an embodiment, the controller is also programmed to: in response to (i) locking the first half-shaft to the second half-shaft, (ii) the difference between the twist of the first half-shaft and the twist of the second half-shaft exceeds a threshold, and (iii) commanding the torque of the motor to be the desired value, truncate the torque of the motor to be less than the desired value.

[0062] According to the present invention, a vehicle is provided, comprising: a motor; a first half-shaft and a second half-shaft, wherein the first half-shaft and the second half-shaft are configured to deliver torque from the motor to a first wheel and a second wheel, respectively; and a controller, wherein the controller is programmed to: truncate the torque of the motor to be less than a desired value in response to (i) locking the first half-shaft to the second half-shaft, (ii) a difference between a twist of the first half-shaft and a twist of the second half-shaft exceeding a threshold, and (iii) commanding the torque of the motor to be a desired value.

[0063] According to an embodiment, the controller is also programmed to: in response to (i) locking the first half-shaft to the second half-shaft, (ii) the displacement of at least one of the first half-shaft and the second half-shaft or the first wheel and the second wheel being within a set of parameters, and (iii) commanding the torque of the motor to the expected value causes the torque allocation to the first half-shaft and the second half-shaft to exceed the torque capacity of at least one of the first half-shaft and the second half-shaft, truncate the torque of the motor to be less than the expected value so that the torque allocation to the first half-shaft and the second half-shaft does not exceed the torque capacity of the first half-shaft or the second half-shaft.

[0064] According to an embodiment, the controller is also programmed to: control the torque of the motor to the desired value in response to (i) unlocking the first half-shaft from the second half-shaft, (ii) shifting at least one of the first half-shaft and the second half-shaft or the first wheel and the second wheel within the set of parameters, and (iii) commanding the torque of the motor to the desired value.

[0065] According to an embodiment, the set of parameters comprises a compound angle exceeding a threshold value, and wherein the compound angle comprises the sum of an angle of at least one of the first and second half-shafts and a steering angle of the first and second wheels.

[0066] According to an embodiment, the set of parameters includes: (i) a droop condition of one of the first wheel and the second wheel; and (ii) a neutral or jump condition of the other of the first wheel and the second wheel.

Claims

1. A vehicle comprising: an electric machine configured to generate torque to propel the vehicle; an axle having (i) a differential configured to receive torque from the electric machine; and (ii) a first half shaft and a second half shaft, the first half shaft and the second half shaft configured to deliver torque from the differential to a first wheel and a second wheel, respectively; a locker configured to (i) be activated to lock the differential such that the first axle half shaft and the second axle half shaft are constrained to rotate in unison, and (ii) be deactivated to unlock the differential such that the first axle half shaft and the second axle half shaft are not constrained to rotate in unison; as well as A controller, the controller being programmed to: In response to (i) activation of the lock, (ii) displacement of at least one of the first and second axles or the first and second wheels according to a set of conditions, and (iii) commanding the torque of the electric machine to a desired value that results in the torque allocation to the first and second axles exceeding the torque capacity of at least one of the first and second axles, truncating the torque of the electric machine to be less than the desired value such that the torque allocation to the first and second axles does not exceed the torque capacity of the first or second axles, and The torque of the motor is controlled to the desired value in response to (i) deactivation of the lock, (ii) displacement of at least one of the first and second half shafts according to the set of conditions, and (iii) commanding the torque of the motor to the desired value.

2. The vehicle of claim 1 , wherein the set of conditions includes a compound angle exceeding a threshold, and wherein the compound angle includes the sum of an angle of at least one of the first half-shaft and the second half-shaft and a steering angle of the first wheel and the second wheel.

3. The vehicle of claim 1, wherein the set of conditions includes: (i) a sagging condition of one of the first wheel and the second wheel; and (ii) a neutral or hop-up condition of the other of the first wheel and the second wheel.

4. The vehicle of claim 1 , wherein the controller is further programmed to control the torque of the motor to the desired value in response to (i) activation of the lock, (ii) shifting of at least one of the first half-shaft and the second half-shaft or the first wheel and the second wheel according to a second set of conditions, and (iii) commanding the torque of the motor to the desired value resulting in the torque allocation to the first half-shaft and the second half-shaft not exceeding the torque capacity of the first half-shaft or the second half-shaft.

5. The vehicle of claim 4, wherein the second set of conditions includes a compound angle less than a threshold, and wherein the compound angle includes the sum of an angle of at least one of the first half-shaft and the second half-shaft and a steering angle of the first wheel and the second wheel.

6. The vehicle of claim 4, wherein the second set of conditions includes: A neutral or jump-on condition of the first wheel and the second wheel.

7. The vehicle of claim 1 , wherein the controller is further programmed to: truncate the torque of the motor to less than the desired value in response to (i) activation of the lock, (ii) a difference between the twist of the first half shaft and the twist of the second half shaft exceeding a threshold, and (iii) commanding the torque of the motor to be the desired value.

8. A vehicle comprising: Motor; a first half shaft and a second half shaft, the first half shaft and the second half shaft configured to deliver torque from the electric machine to a first wheel and a second wheel, respectively; as well as A controller programmed to: in response to (i) locking the first half-shaft to the second half-shaft, (ii) shifting of at least one of the first half-shaft and the second half-shaft or the first wheel and the second wheel, and (iii) commanding the torque of the motor to a desired value resulting in the torque allocation to the first half-shaft and the second half-shaft exceeding the torque capacity of at least one of the first half-shaft and the second half-shaft, truncate the torque of the motor to less than the desired value so that the torque allocation to the first half-shaft and the second half-shaft does not exceed the torque capacity of the first half-shaft or the second half-shaft.

9. The vehicle of claim 8, wherein the controller is further programmed to control the torque of the motor to the desired value in response to (i) unlocking the first axle from the second axle, (ii) shifting at least one of the first axle and the second axle or the first wheel and the second wheel, and (iii) commanding the torque of the motor to the desired value.

10. The vehicle of claim 8, wherein the displacement of at least one of the first and second half-axles or the first and second wheels corresponds to a compound angle exceeding a threshold, and wherein the compound angle comprises the sum of an angle of at least one of the first and second half-axles and a steering angle of the first and second wheels.

11. The vehicle of claim 8, wherein the controller is further programmed to: control the torque of the motor to the desired value in response to (i) locking the first axle to the second axle, (ii) a second shift of at least one of the first axle and the second axle or the first wheel and the second wheel, and (iii) commanding the torque of the motor to the desired value resulting in the torque allocation to the first axle and the second axle not exceeding the torque capacity of the first axle or the second axle.

12. The vehicle of claim 8, wherein the controller is further programmed to: truncate the torque of the motor to less than the desired value in response to (i) locking the first half shaft to the second half shaft, (ii) a difference between the twist of the first half shaft and the twist of the second half shaft exceeding a threshold, and (iii) commanding the torque of the motor to be the desired value.

13. A vehicle comprising: Motor; a first half shaft and a second half shaft, the first half shaft and the second half shaft configured to deliver torque from the electric machine to a first wheel and a second wheel, respectively; as well as A controller is programmed to: in response to (i) locking the first half shaft to the second half shaft, (ii) a difference between the twist of the first half shaft and the twist of the second half shaft exceeding a threshold, and (iii) commanding the torque of the motor to be a desired value, truncate the torque of the motor to be less than the desired value.

14. The vehicle of claim 13, wherein the controller is further programmed to: in response to (i) locking the first axle to the second axle, (ii) displacement of at least one of the first axle and the second axle or the first wheel and the second wheel within a set of parameters, and (iii) commanding the torque of the motor to the desired value results in the torque allocation to the first axle and the second axle exceeding the torque capacity of at least one of the first axle and the second axle, truncate the torque of the motor to be less than the desired value so that the torque allocation to the first axle and the second axle does not exceed the torque capacity of the first axle or the second axle.

15. The vehicle of claim 14, wherein the set of parameters includes a compound angle exceeding a threshold, and wherein the compound angle includes the sum of an angle of at least one of the first half-shaft and the second half-shaft and a steering angle of the first wheel and the second wheel.

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