Patent ID: 12233845

The above features and advantages and other features and advantages of the present teachings are readily apparent from the following detailed description of the modes for carrying out the present teachings when taken in connection with the accompanying drawings. It should be understood that even though the following Figures embodiments may be separately described, single features thereof may be combined to additional embodiments.

DETAILED DESCRIPTION

As required, detailed embodiments of the present disclosure are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the disclosure that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present disclosure.

FIG.1illustrates a schematic view of a hybrid electric vehicle10having a control system12for mitigating driveline torque spikes in accordance with one non-limiting aspect of the present disclosure. The vehicle10is illustrated for exemplary non-limiting purposes as being a hybrid of the type having an internal combustion engine (ICE)14and an electric motor16to cooperatively provide rotational force/torque to one or more of a plurality of wheels20,22,24,26. The vehicle10is shown to include a driveline30configured to connect the ICE14and the motor16to the front wheels20,24. The driveline30may include a transmission34, a driveshaft36, a differential38, axles40,42, and/or other componentry to facilitate conveying rotative force from the ICE14and/or the motor16to the wheels20,22,24,26. The vehicle10is predominately described as a two-wheel drive automobile for exemplary non-limited purposes as the present disclosure fully contemplates its use and application with four-wheel drive automobiles and other, non-automobile types of vehicles.

A motor controller46may be configured to generate control signals associated with directing and otherwise implementing desired control of the ICE14and/or the motor16. One or more battery packs50may be configured to supply DC power to a DC-AC inverter52, which then supplies AC power to the electric motor16as directed by the motor controller46. The vehicle10is shown to include the ICE14for exemplary purposes as the present disclosure fully contemplates its use and application with battery-only types of vehicles, i.e., vehicles that rely solely on the motor16for propulsion. The motor controller46may be considered as a motor controller unit (MCU), a main controller, an engine control unit (ECU), and/or other type of controller configured to facilitate controlling a number of vehicle operations according to the processes contemplated herein.

The motor controller46may be configured to interact directly with vehicle components and/or through a vehicle network or bus to facilitate exchanging information, data, commands, etc. with systems, sensors, and other elements within the vehicle10. One non-limiting aspect of the present disclosure contemplates the motor controller46being configured to interact with additional controllers56,58,60or to itself include the additional controllers56,58,60. The controllers46,56,58,60may be functional constructs associated with activities resulting from one or more processors executing a plurality of non-transitory instructions stored on a computer readable storage medium, e.g., the operations, processes, commands, functions, etc. of each controller46,56,58,60may be defined according to separate non-transitory instructions associated therewith. The controllers46,56,58,60, as such, are presented separately for non-limiting purposes in order to demarcate contemplated control functionality.

The motor controller46may be the final arbitrator of torque commands used to control to the ICE14and/or the motor16. The torque commands may be instructions or other information provided from the motor controller46for purposes of directing propulsion of the vehicle10. While the contemplated control may be implemented in conjunction with use of the ICE14, the present disclosure is predominantly described with respect to the motor controller46arbitrating between various torque commands of the controllers56,58,60for purposes of selecting one or more of the torque commands to control operation of the motor16, which may occur independently of or in cooperation with the ICE14. In this exemplary scenario, the controller56may be a wheel slip controller configured to generate a wheel slip torque command, the controller58may be a wheel flare controller configured to generate a wheel flare torque command, and the controller60may be configured as a motor spike controller configured to generate a motor spike torque command. The motor controller46may be tasked with arbitrating between one or more of the wheel slip, wheel flare, and motor spike torque commands for purposes of directing operation of the motor16and/or other components associated therewith, e.g., directing operations of the battery50, the inverter52, etc.

The wheel slip and wheel flare controllers56,58may be closed-loop type of controllers configured to facilitate generating corresponding torque commands. The wheel slip and wheel flare controllers56,58may be generally characterized as control functions focused on preventing the wheels20,22,24,26from slipping, i.e., to maximize tractive force between the wheel20,22,24,26and surface of travel. The wheel slip torque command generated with the wheel slip controller56may be based on a wheel speed measured at one or more of the wheels20,22,24,26and configured for controlling the motor16to mitigate wheel slip. The wheel flare torque command generated with the wheel flare controller58may be based on a transmission output speed of an output of the transmission34and configured for controlling the motor16to mitigate a wheel flare of the wheels20,22,24,26.

The motor spike controller60may be an open-loop type of controller configured to generate the motor spike torque command as a feedforward type of command. The feedforward nature of the motor spike controller60may be beneficial in providing a quicker response to wheel slippage than the wheel slip and flare controllers56,58and/or a response independent of feedback type of loop such that it can be quickly implemented. One non-limiting aspect of the present disclosure contemplates the motor spike controller60being configured to mitigate driveline torque spikes within the driveline30. Driveline torque spikes may occur under various circumstances and may be generally considered as a temporary or short-lived event whereby a quick response may be beneficial in limiting strain on the driveline30or other systems of the vehicle10.

Driveline torque spikes may occur, for example, in response to an ice clunk event or when the vehicle10crosses a boundary between surfaces having coefficients of friction differing by a predefined amount. Driveline torque spikes may result from a rapid decrease in wheel speed when crossing a boundary from a low friction to a high friction surface and vice versa from a rapid increase in wheel speed when crossing a boundary from a high friction to a low friction surface. Driveline torque spikes may also occur as a result of a panic break event when a vehicle operator engages a braking system in such a manner that the wheel speed suddenly and dramatically drops faster than a predefined rate. Driveline torque spikes may be considered as an imbalance between the motor16and the driven wheels20,24associated with the motor16and/or the driven wheels20,24operating in a manner that disrupts speed ratios, gearing ratios, and/or other design ratios desired for typical operation of the driveline30.

To limit the effect of the imbalance and/or to mitigate the amount of torque spike, one non-limiting aspect of the present disclosure contemplates the motor spike controller60generating the motor spike torque command in a manner sufficient for using the motor16as an actuator whereby the actuator effectively imparts or consumes energy/force to/from the driveline30to mitigate the torque spikes. The motor spike torque command may optionally be used in this manner to inertia match and/or speed match an inertia and/or speed of the motor16with an inertia and/or speed of the driven wheels20,24such that the two (motor and wheel) rotate with essentially the same pace. The matching may take into consideration componentry of the driveline30, i.e., ratios and gearing associated with the transmission34, driveshaft36, differential38, etc. The motor spike torque command may be generated in an attempt to quickly ward off or limit shaft twist of the driveshaft36and the axles40,42, such as to re-balance those and the other components of the driveline30to a state preceding the torque spike event.

The motor spike torque command may be implemented in an attempt to better balance tortional forces in an effort to quickly ameliorate disparity between the driven wheels20,24and the motor16occurring as a result of the torque spike event. One non-limiting aspect of the present disclosure contemplates generating the motor spike torque command according to a torque spike equation. The torque spike equation may be represented as:
Tm=Jm×{dot over (N)}w×Ratiowherein Tmis the motor spike torque command, Jmis a motor inertia of the motor, {dot over (N)}wis a wheel acceleration of the wheel, and Ratio is a constant representing a speed ratio between the motor16and the one or more driven wheels20,24. The motor inertia (Jm) may be a physical value or constant associated with material properties, sizing, and other design characteristics of the motor16. The wheel acceleration ({dot over (N)}w) may be a calculated value based on a wheel speed sensor at one of the driven wheels20,24assessing a rate of change, e.g., the rate of change associated with the wheel speed suddenly increasing or decreasing due to ice clunk, panic braking, disparate frictional surfaces, etc. The speed ratio (Ratio) may be a physical value or constant associated with material properties, sizing, and other design characteristics of the driveline30, e.g., a value derived according to the gearing, step-down, mechanical advantages, etc. associated with interconnecting the wheels20,24with the motor16.

FIG.2illustrates a flowchart70of a control method for mitigating driveline torque spike in an electric vehicle in accordance with one non-limiting aspect of the present disclosure. The method may improve operation of an electric vehicle by mitigating driveline torque spikes, and thereby the undesirable strain on a driveline and other mechanisms, such as when a vehicle crosses boundaries between surfaces having differing coefficients of friction, experiences panic breaking, and/or is otherwise subject to events producing wheel slip or other rapid wheel speed changes. The method, and associated operations, processes, functions, commands, etc., may be facilitated with a controller having a corresponding set of non-transitory instructions stored on a computer readable storage medium such that, when executed with a processor, the non-transitory instructions are sufficient to facilitate mitigating driveline torque spike in the manner contemplated herein, i.e., by generating a motor spike torque command for use by a motor controller to control a motor to mitigate driveline torque spikes.

Block72relates to instigating the contemplated control strategy and methodology. This may include a motor controller or other vehicle controller initiating its operation or otherwise collecting data according to processes needed to identify various vehicle operating states and related operator demand. One non-limiting aspect of the present disclosure contemplates the method being implemented in accordance with wheel slip and wheel flare controls such that the initialization process may include the motor controller initializing each of a wheel slip controller, a wheel flare controller, and a motor spike controller to respectively generate a wheel slip torque command, a wheel flare torque command, and the motor spike torque command. The motor controller may be configured to receive each of these torque commands and to arbitrate corresponding control of the motor, i.e., to select one or more of the torque commands for use in controlling the motor and/or the components associated therewith (e.g., battery, inverter, etc.).

Block74relates to determining whether either one of a wheel slip controller and/or a wheel flare controller are actively being engaged to respectively generate the wheel slip and/or wheel flare torque commands. This assessment may be useful in identifying conditions or events where the vehicle is beginning to experience wheel slippage or conditions when will slippage is likely or possible to occur in the near future, such as when the wheel speed is greater than a wheel speed threshold or the output of the transmission is greater than a predetermined output acceleration threshold. Integrating generation of the motor spike torque command with the torque commands of the wheel slip and flare controllers may be beneficial in limiting programming and other processing associated with the implementation thereof. In other words, rather than undertaking programming or otherwise generating procedures for detecting events preceding a torque spike event or making independent measurements, the motor spike controller may more simply identify such a need from binary flags set for the wheel slip and flare controllers. The generation of the motor spike torque command, alternatively, may be perpetually generated throughout vehicle operations and provided continuously to the motor controller. This may be beneficial in ameliorating time delays associated with triggering generation of the motor spike torque command and its deliverance to the motor controller. The motor controller may be correspondingly configured to ignore the motor spike torque command until conditions indicate a need for the use thereof.

Block76relates to calculating a wheel acceleration for one or more of the wheels being driven by the motor. The wheel acceleration may be based on a wheel speed measured with a sensor positioned at the corresponding wheel, such as with a sensor associated with an antilock braking system (ABS).

Block78relates to determining whether the wheel acceleration exceeds a predefined motor spike threshold. The motor spike threshold may be a design parameter set according to situations where driveline torque spikes may be possible. The wheel acceleration threshold, for example, may be specified with a sufficient margin such that the motor spike threshold is less than that which would actually induce a driveline torque spike. The motor spike threshold may be calculated as an absolute value such that the threshold may be exceeded with a sufficient amount of acceleration or deceleration. The use of the wheel acceleration threshold may be beneficial in comparison to a wheel speed threshold or a transmission speed threshold, i.e., the thresholds utilized by the wheel slip and flare controllers, due to acceleration being a more accurate representation for driveline torque spikes or conditions likely to cause shaft twists.

Block80relates to generating the motor spike torque command according to a torque spike equation. The torque spike equation may be represented as:
Tm=Jm×{dot over (N)}w×Ratiowherein Tmis the motor spike torque command, Jmis a motor inertia of the motor, {dot over (N)}wis a wheel acceleration of the wheel, and Ratio is a constant representing a speed ratio between the motor and the one or more driven wheels. The motor inertia (Jm) may be a physical value or constant associated with material properties, sizing, and other design characteristics of the motor. The wheel acceleration ({dot over (N)}w) may be a calculated value based on a wheel speed sensor at one of the driven wheels assessing a rate of change, e.g., the rate of change associated with the wheel speed suddenly increasing or decreasing due to ice clunk, panic braking, disparate frictional surfaces, etc. The speed ratio (Ratio) may be a physical value or constant associated with material properties, sizing, and other design characteristics of the driveline.

The present disclosure may be embodied in many different forms. Representative examples are shown in the various drawings and described herein in detail as non-limiting representations of the disclosed principles. To that end, elements and limitations described above, but not explicitly set forth in the appended claims, should not be incorporated into the claims, singly or collectively, by implication, inference, or otherwise. Moreover, unless specifically disclaimed, use of the singular includes the plural and vice versa, the terms “and” and “or” shall be both conjunctive and disjunctive, “any” and “all” shall both mean “any and all”, and the words “including”, “containing”, “comprising”, “having”, and the like shall mean “including without limitation”. The terms “comprising”, “including”, and “having” are inclusive and therefore specify the presence of stated features, steps, operations, elements, or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, or components. Orders of steps, processes, and operations may be altered when possible, and additional or alternative steps may be employed. As used in this specification, the term “or” includes any one and all combinations of the associated listed items. The term “any of” is understood to include any possible combination of referenced items, including “any one of” the referenced items.

“A”, “an”, “the”, “at least one”, and “one or more” are used interchangeably to indicate that at least one of the items is present. A plurality of such items may be present unless the context clearly indicates otherwise. All numerical values of parameters (e.g., of quantities or conditions) in this specification, unless otherwise indicated expressly or clearly in view of the context, including the appended claims, are to be understood as being modified in all instances by the term “about” whether or not “about” actually appears before the numerical value. “About” indicates that the stated numerical value allows some slight imprecision (with some approach to exactness in the value; approximately or reasonably close to the value; nearly). If the imprecision provided by “about” is not otherwise understood in the art with this ordinary meaning, then “about” as used herein indicates at least variations that may arise from ordinary methods of measuring and using such parameters. In addition, a disclosure of a range is to be understood as specifically disclosing all values and further divided ranges within the range.

Words of approximation such as “about”, “almost”, “substantially”, “generally”, “approximately”, etc., may be used herein in the sense of “at, near, or nearly at”, or “within 0-5% of”, or “within acceptable manufacturing tolerances”, or logical combinations thereof. Also as used herein, a component that is “configured to” perform a specified function is capable of performing the specified function without alteration, rather than merely having potential to perform the specified function after further modification. In other words, the described hardware, when expressly configured to perform the specified function, is specifically selected, created, implemented, utilized, programmed, and/or designed for the purpose of performing the specified function. For consistency and convenience, directional adjectives may be employed throughout this detailed description corresponding to the illustrated embodiments. Those having ordinary skill in the art will recognize that terms such as “above”, “below”, “upward”, “downward”, “top”, “bottom”, etc., may be used descriptively relative to the figures, without representing limitations on the scope of the disclosure, as defined by the claims. Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the drawing figures. Spatially relative terms may be intended to encompass different orientations of the device or system in use or operation in addition to the orientation depicted in the drawing figures.

While various embodiments have been described, the description is intended to be exemplary, rather than limiting and it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible that are within the scope of the embodiments. Any feature of any embodiment may be used in combination with or substituted for any other feature or element in any other embodiment unless specifically restricted. Accordingly, the embodiments are not to be restricted except in light of the attached claims and their equivalents. Also, various modifications and changes may be made within the scope of the attached claims. Although several modes for carrying out the many aspects of the present teachings have been described in detail, those familiar with the art to which these teachings relate will recognize various alternative aspects for practicing the present teachings that are within the scope of the appended claims. It is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and exemplary of the entire range of alternative embodiments that an ordinarily skilled artisan would recognize as implied by, structurally and/or functionally equivalent to, or otherwise rendered obvious based upon the included content, and not as limited solely to those explicitly depicted and/or described embodiments.