Patent ID: 12246717

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

With reference toFIG.1, there is illustrated a schematic view of an exemplary vehicle100including a powertrain102incorporated within vehicle100. In the illustrated embodiment, the powertrain102includes an engine104, such as an internal combustion engine, structured to generate power for the vehicle100. The powertrain102further includes a transmission106connected to the engine104for adapting the output torque of the engine104and transmitting the output torque to a driveline107including drive shaft108. In certain embodiments, the transmission106is an automated manual transmission that may be disengageably connected to an engine crankshaft105via a clutch109. Transmission106may alternatively or additionally include an actuator119that actuates transmission106to achieve a neutral gear position to disconnect engine104from driveline107. Vehicle100may also include a starter123which can be used to rotate engine104from a stalled or zero speed condition to achieve a cranking speed for starting of engine104.

In the rear wheel drive configuration illustrated for vehicle100, the driveline107of powertrain102includes a final drive110having a rear differential112connecting the drive shaft108to rear axles114a,114b. It is contemplated that the components of powertrain102may be positioned in different locations throughout the vehicle100. In one non-limiting example of a vehicle100having a front wheel drive configuration, transmission106may be a trans axle and final drive110may reside at the front of the vehicle100, connecting front axles116aand116bto the engine104via the transaxle. It is also contemplated that in some embodiments the vehicle100is in an all-wheel drive configuration.

In the illustrated embodiment, vehicle100includes two front wheels122a,122bmounted to front axles116a,116b, respectively. Vehicle system100further includes two rear wheels126a,126bmounted to rear axles114a,114b, respectively. It is contemplated that vehicle100may have more or fewer wheels than illustrated inFIG.1. Vehicle100may also include various components not shown, such a fuel system including a fuel tank, a front differential, a braking system, a suspension, an engine intake system and an exhaust system, which may include an exhaust aftertreatment system, to name a few examples.

Vehicle100includes an electronic or engine control unit (ECU)130, sometimes referred to as an electronic or engine control module (ECM), or the like, which is directed to regulating and controlling the operation of engine104. A transmission control unit (TCU)140is illustrated in vehicle100, which is directed to the regulation and control of transmission106operation. ECU130and TCU140are each in electrical communication with a plurality of vehicle sensors (not shown) in vehicle100for receiving and transmitting conditions of vehicle100, such as temperature and pressure conditions, for example. In certain embodiments, the ECU130and the TCU140may be combined into a single control module, commonly referred to as a powertrain control module (PCM) or powertrain control unit (PCU), or the like. It is contemplated that ECU130and/or TCU140may be integrated within the engine104or transmission106, respectively. Other various electronic control units for vehicle subsystems are typically present in vehicle system100, such as a braking system electronic control unit and a cruise control electronic control unit, for example, but such other various electronic control units are not show in vehicle100to preserve clarity.

Vehicle system100further includes a coasting management (CM) controller150, which may be directed to the control of the operations described herein and/or directed toward an intermediary control for the regulation and control of the powertrain102in vehicle system100. In the illustrated embodiment, CM controller150is in electrical communication with each of the ECU130and TCU140. In certain embodiments, at least a portion of the CM controller150may be integrated within, or be, the ECU130and/or TCU140. CM controller150may further be in electrical communication with one or more of the plurality of vehicle sensors in vehicle100for receiving and transmitting conditions of vehicle100, such as temperature and pressure conditions, route conditions, terrain conditions, speed conditions, and weather conditions, for example. It is contemplated that at least a portion of the conditions and/or measured inputs used for interpreting signals by the CM controller150may be received from ECU130and/or TCU140, in addition to or alternatively to the plurality of vehicle sensors. Furthermore, the CM controller150may include a processor, and may also be referred to as a control unit.

The CM controller150includes stored data values, constants, and functions, as well as operating instructions stored on, for example, a computer readable medium. Any of the operations of exemplary procedures described herein may be performed at least partially by the CM controller150. In certain embodiments, the ECU130, TCU140, and/or CM controller150includes one or more control units disclosed herein with one or more modules structured to functionally execute the operations of the control unit. The description herein including modules emphasizes the structural independence of the aspects of the ECU130, TCU140, and/or CM controller150, and illustrates one grouping of operations and responsibilities of the ECU130, TCU140, and/or CM controller150. Other groupings that execute similar overall operations are understood within the scope of the present application. Modules may be implemented in hardware and/or instructions on computer readable medium, and modules may be distributed across various hardware or computer readable medium components. More specific descriptions of certain embodiments of control operations are included below. Operations illustrated are understood to be exemplary only, and operations may be combined or divided, and added or removed, as well as re-ordered in whole or part, unless stated explicitly to the contrary herein.

Certain operations described herein include operations to interpret or determine one or more parameters. Interpreting or determining, as utilized herein, includes receiving values by any method known in the art, including at least receiving values from a datalink or network communication, receiving an electronic signal (e.g., a voltage, frequency, current, or pulse-width modulation (PWM) signal) indicative of the value, receiving a software parameter indicative of the value, reading the value from a memory location on a computer readable medium, receiving the value as a run-time parameter by any means known in the art, and/or by receiving a value by which the interpreted or determined parameter can be calculated, and/or by referencing a default value that is interpreted or determined to be the parameter value.

In certain embodiments, the ECU130, TCU140, and/or CM controller150receives operating inputs, such as a fuel amount input, a weather conditions input, and a route conditions input from one or more sensors and/or one or more external devices for detecting route conditions. The CM controller150may also receive engine conditions input from the ECU130and transmission conditions input from the TCU140. Engine conditions may include a brake actuation parameter, a throttle position parameter, a torque request parameter, an ambient air pressure, an ambient air temperature, an engine temperature, an engine torque, an engine speed, an engine speed rate of change, an engine degrade state, and a brake position, for example. Transmission conditions may include a transmission gear ratio, a current transmission gear, a final drive ratio, a clutch actuator position, and a neutral gear state, for example.

In operation, CM controller150controls vehicle operations that provide both anticipated and currently desired vehicle100operation behavior to optimize fuel economy in response to the operating inputs, the engine conditions input, the transmission conditions input, engine fueling parameters, and/or engine braking/friction parameters. CM controller150is operable to assume active control of the vehicle100, regulating a vehicle speed, the engine torque curve, and/or other powertrain102operating conditions to ensure optimal vehicle100operation, or passive control which allows the operator to take recommended actions. In the present application, CM controller150is configured to interpret operating inputs, engine conditions, and transmission conditions to determine if a coasting opportunity is available, and to automatically (without operator input) disconnect the engine104from the driveline107to enable coasting of vehicle100to obtain, for example, fuel economy benefits. Further fuel economy benefits can be provided by shutting off engine104during coasting by cutting off fuel so that the engine104does not idle during coasting operations.

In response to CM controller150interpreting or receiving an input that a coasting opportunity is available for vehicle100and desired, CM controller150outputs, in a first embodiment, a transmission gear command to TCU140or, in a second embodiment, a clutch actuator command to TCU140. The transmission gear command and clutch actuator command each disengage engine104from driveline107in response to coasting opportunity to provide coasting operation of vehicle100. In addition, the CM controller150can shut off engine104during the coasting operation by cutting off fuel to engine104during the coasting operation.

In one embodiment, transmission gear command controls an actuator119(shown inFIG.1as located within the contours of the automated manual transmission106, but it will be appreciated that the actuator119can be located elsewhere) that actuates transmission106to achieve a neutral gear position to disconnect engine104from driveline107. In another embodiment, clutch actuator command actuates a clutch actuator111associated with clutch109to disengage clutch109and disconnect engine104from driveline107. The transmission gear command or clutch actuator command can be activated by CM controller150during cruise control operation of vehicle100, or anytime CM controller150is active for controlling operations of vehicle100in response to certain conditions. The coasting mode of operating can be overridden by operator input, such as when the operator increases the throttle position, pushes a brake pedal, or moves a gear level, to re-engage engine104to driveline107and terminate coasting operation of vehicle100.

Although as discussed above the CM controller150can be structured to output a command to disengage the engine104from the driveline107and cut off fueling to engine104in response to an engine off coasting opportunity, the CM controller150can also be structured to monitor performance of the vehicle100and re-start engine104and re-engage the engine104to the driveline107when conditions warrant. For example, such engine104re-start and engine104re-engagement to the driveline107can occur when vehicle speed and/or predicted speed needs to be controlled by operating engine104, such as to prevent the speed from dropping below a minimum threshold, to control vehicle speed in response to an object or vehicle in front of the coasting vehicle, or other event in which engine off coasting is to be terminated. The conditions dictating an engine re-start can be monitored by the CM controller150or other suitable module or control unit during the engine off coasting event.

FIGS.2A-2Ddepict embodiments of coasting control schemes using both engine off coasting and idle coasting. In both idle coasting and engine off coasting the engine104is disengaged from the driveline107such as by holding the clutch109open or neutralizing the transmission106in response to the control logic in CM controller150concluding coasting conditions are met. Idle coasting maintains fueling of the engine so the engine maintains idle speed. Engine off coasting differs from idle coasting in that fueling to the engine is cut off or terminated during the coasting event, allowing the engine to naturally decelerate until stalling. Engine off coasting can reduce the total fuel used over the mission as compared to idle coasting. In addition, engine drag is reduced and vehicle momentum is increased as compared to idle coasting operation, allowing a delay in fueling resumption. Engine off coasting can also be employed as extension of idle coasting in certain embodiments when conditions indicated it is favorable to shut off the engine rather than maintaining an idling engine.

Shown inFIG.2Ais a schematic of vehicle100on a route segment210with an overall downhill grade having an intermediate uphill segment212.FIGS.2B-2Ddepict various control schemes including an engine on/off status inFIG.2B, the vehicle speed inFIG.2C, and the fueling activity inFIG.2D. Any of the control activities for traversing the route segment can be implemented in the CM controller150or other controller/control modules discussed herein.

FIG.2Bdepicts the engine status along the route segment210. The engine off coasting mode of operation is active along the initial downhill part of the route segment. The engine off coasting mode is temporarily deactivated to traverse the intermediate uphill segment212by re-starting engine104, and then the engine off coasting mode of operation is re-activated and the engine is shut off by cutting fuel to engine104after reaching the subsequent downhill segment. At the end of the last downhill segment, the engine off coasting mode of operation is terminated and the engine is turned on by re-starting the engine104.

The engine off coasting mode of operation will be understood as a condition in which the engine104is disengaged from driveline107in response to a coasting opportunity, where “Engine Off” inFIG.2Brepresents cutting of fuel to the engine104so the engine104stalls. “Engine On” inFIG.2Brepresents re-engagement of the engine107to the driveline107and resumption of fueling to engine104so the engine104propels the vehicle. However, embodiments in which the coasting mode of operation with the engine off is maintained even during the intermediate uphill segment are also contemplated when predicted vehicle speed along the intermediate uphill segment is maintained above minimum threshold even while engine off coasting is active.

FIG.2Cdepicts the speed profiles of the vehicle in which an idle coasting speed is shown in line220, and engine off coasting speed is shown in line230. A lower, minimum speed threshold is shown that can be used to determine when to terminate the coasting mode of operation based on the various inputs to CM controller150and/or a predicted vehicle speed along the route segment210, and an upper speed threshold (EB activation) is shown in which engine braking can be activated to maintain the vehicle speed below the upper speed threshold.FIG.2Ddepicts fuel flow rate within engine104. A baseline fueling amount is shown in line240during idle coasting that is maintained during idle coasting operations. In contrast, fueling to engine104is shown in line250with zero fueling during engine off coasting operation. Fueling is re-initiated while the engine off coasting mode is exited during the intermediate uphill segment212. The engine off coasting can be resumed on the downhill segment following the intermediate uphill segment212.

When the engine off coasting is terminated, it is necessary to re-start the engine104to resume nominal operations for vehicle100.FIGS.3A-6Eshow various embodiments of engine re-start strategies that can be employed by CM controller150and/or in any of the other control units/control modules discussed herein in response to termination of engine off coasting and resumption of nominal engine operations to propel the vehicle100. In an embodiment, CM controller150is configured to select one of the re-start modes discussed herein in response to one or more operating condition inputs, such as a predicted vehicle speed at re-start of the engine104for one or more upcoming route segments. In an embodiment, the engine re-start modes are ranked in a hierarchy of preference depending on the route conditions and/or operating conditions of the vehicle100. If a preferred or higher ranked re-start mode is not available, then the next ranked re-start mode can be selected.

FIGS.3A-3Edepict a first re-start mode for engine104in which the transmission106is solely responsible for bringing engine104back to a desired operating speed for final re-engagement to the driveline107, such as by engagement of clutch109and/or actuator119.FIG.3Aincludes an engine speed profile, andFIG.3Bshows a profile for clutch position relative to engine speed over time. Closing of the clutch109is controlled to ramp up the engine speed to a desired operating speed S for final engagement of the engine to the driveline107in a synced condition. The closing rate of clutch109is controlled so that the engine speed gradually increases from a stalled condition to the desired operating speed S, when the clutch109is completely closed to finally engage engine104with driveline107in a synced condition.

As shown inFIG.3C, normal or nominal fueling of engine104is resumed when the clutch109is completely closed, at which time the driveline107is completely engaged to engine104as shown inFIG.3E. As shown inFIG.3D, the starter123is not used to re-start the engine104in this embodiment. The first re-start mode can be selected when the fastest mode for re-starting the engine is desired. However, the first re-start mode may be ranked lower in the hierarchy of re-start modes disclosed herein in order to minimize wear of clutch109.

FIGS.4A-4Edepict a second re-start mode for engine104in which clutch109and fueling to engine104are both employed to bring engine104back to a desired operating speed for final re-engagement to the driveline107.FIG.4Aincludes an engine speed profile, and FIG.4B shows a profile for clutch position relative to engine speed over time. Closing of the clutch109is controlled at a rate that ramps up the engine speed from a stalled condition to a first speed threshold S1at which fueling of engine104re-initiated for starting the engine104as shown inFIG.4C. Closing of clutch109and fueling of engine104continues simultaneously until the engine104reaches the desired operating speed S, when the clutch109is completely closed to complete the engagement with the speed of the engine104synced to the speed of the driveline107.

As shown inFIG.4C, normal or nominal fueling of engine104is resumed when the clutch109is completely closed, at which time the driveline is engaged as shown inFIG.4E. As shown inFIG.4D, the starter123is not used to re-start the engine in this embodiment. The second re-start mode reduces clutch wear as compared to the first re-start mode discussed above with respect toFIGS.3A-3E, but does involve repeatable fuel delivery and response to bring the engine104up to speed S for re-engagement.

FIGS.5A-5Edepict a third re-start mode for engine104in which clutch109and fueling to engine104are both employed in a manner that differs fromFIGS.4A-4Eto bring engine104back to a desired operating speed for final re-engagement to the driveline107.FIG.5Aincludes an engine speed profile, andFIG.5Bshows a profile for clutch position relative to engine speed over time. Closing of the clutch109is controlled at a rate that ramps up the engine speed from a stalled condition to a second speed threshold S2, at which time the clutch109is opened again and fueling of engine104re-initiated for starting the engine104as shown inFIG.5C. Speed threshold S2can be, for example, a cranking or idle speed of engine104. Fueling of engine104continues to increase until engine104approaches or reaches the desired operating speed S. Clutch109is then completely closed from its open condition to complete the engagement of engine104with driveline107with the speed of the engine104synced to the speed of the driveline107.

As shown inFIG.5C, normal or nominal fueling of engine104is resumed when the clutch109is completely closed, at which time the driveline107is engaged as shown inFIG.5E. As shown inFIG.5D, the starter123is not used to re-start the engine104in this embodiment. The third re-start mode reduces clutch wear as compared to the first re-start mode discussed above with respect toFIGS.3A-3E, but does involve repeatable fuel delivery response like the re-start mode ofFIGS.4A-4E, and also repeatable clutch positioning accuracy in contrast to the second re-start mode discussed above with respect toFIGS.4A-4E.

FIGS.6A-6Edepict a fourth re-start mode for engine104in which starter123and fueling to engine104are both employed to bring engine104back to a desired operating speed from an engine off coasting mode of operation. This fourth re-start mode can be used, for example, as a backup mode when the clutch109is unresponsive or the other restart modes discussed above don't work as intended.FIG.6Aincludes an engine speed profile, andFIG.6Bshows a profile for clutch position relative to engine speed over time. Closing of the clutch109, if possible, is delayed until engine104reaches desired operating speed threshold S. In order to initiate re-starting of engine104, starter is engaged as shown inFIG.6Dto increase the speed of engine104to a third speed threshold S3. At third speed threshold S3fueling of engine104is re-initiated as shown inFIG.6Cfor starting the engine104. Fueling of engine104continues to increase until the engine104reaches the desired operating speed S, and then the clutch109is completely closed, if possible or if not already closed, to complete the engagement with the speed of the engine104synced to the speed of the driveline107.

As shown inFIG.6C, normal or nominal fueling of engine104is resumed when the clutch109is completely closed, at which time the driveline107is engaged as shown inFIG.6E. The fourth re-start mode can be, for example, an emergency mode that allows vehicle100to retain full braking, steering, charging, and driver comfort capabilities in order to get the vehicle100stopped or out of the immediate path of travel. Since wear and tear on starter123is increased, this fourth starting mode can also, for example, be used as a backup mode in the event other starting modes experience problems preventing completion, and/or ranked last in the hierarchy of starting mode selection.

According to one aspect of the present disclosure, a method includes operating a vehicle in a coasting mode during which fuel to an engine of the vehicle is cut-off and a driveline of the vehicle is disengaged from the engine while the vehicle coasts; determining the coasting mode of operation of the vehicle is to be terminated; in response to the determining, selecting an engine re-start mode that increases a speed of the engine by coupling the engine to the driveline and re-initiating fueling to the engine; and re-engaging the driveline to the engine in response to the speed of the engine being increased to a desired operating speed.

In an embodiment of the method, coupling the engine to the driveline includes initiating closing a clutch between the driveline and the engine. In a refinement of this embodiment, closing the clutch is initiated before re-initiating fueling to the engine.

In a further refinement of this embodiment, fueling to the engine is re-initiated during closing the clutch. In yet a further refinement, fueling to the engine is re-initiated in response to the speed of the engine increasing to a speed threshold less than the desired operating speed.

In a further refinement of this embodiment, the method includes re-opening the clutch before re-initiating fueling to the engine, and then re-initiating fueling to the engine while the clutch is re-opened. In yet a further refinement, the clutch is re-opened in response to the speed of the engine increasing to a first threshold less than the desired operating speed. In yet a further refinement, the method includes re-closing the clutch in response to the speed of the engine achieving a second threshold greater than the first threshold via fueling to the engine. In yet a further refinement, the second threshold approximates the desired operating speed.

In an embodiment of the method, the speed of the engine is increased by engaging a starter to increase the speed of the engine to a first threshold before re-initiating fueling the engine, and then disengaging the starter in response to the speed of the engine reaching the first threshold. In a refinement of this embodiment, the method includes closing a clutch after increasing the speed of the engine to a second threshold greater than the first threshold via re-initiating fueling to the engine.

In another aspect of the present disclosure, there is disclosed an apparatus that includes a coasting controller for a vehicle having an engine structured to provide motive power to the vehicle. The coasting controller is configured to operate the vehicle in a coasting mode during which fuel to the engine of the vehicle is cut-off and a driveline of the vehicle is disengaged from the engine while the vehicle coasts; determine the coasting mode is to be terminated; couple the engine to the driveline and re-initiate fueling of the engine to increase the speed of the engine; and re-engage the driveline to the engine in response to the speed of the engine reaching a desired operating speed.

In an embodiment, the coasting controller is configured to increase the speed of the engine by initiating closing a clutch between the driveline and the engine. In a refinement of this embodiment, the coasting controller is configured to initiate closing the clutch before fueling to the engine is re-initiated.

In yet a further refinement of the above embodiment, the coasting controller is configured to re-initiate fueling to the engine during closing the clutch. In yet a further refinement, the coasting controller is configured to re-initiate fueling to the engine response to the speed of the engine increasing to a speed threshold less than the desired operating speed.

In still a further refinement, the coasting controller is configured to re-open the clutch before fueling to the engine is re-initiated, and then re-initiate fueling to the engine while the clutch is re-opened. In a further refinement, the coasting controller is configured to re-open the clutch in response to the speed of the engine increasing to a first threshold less than the desired operating speed. In yet a further refinement, the coasting controller is configured to re-close the clutch in response to the speed of the engine achieving a second threshold greater than the first threshold via fueling re-initiated to the engine. In a further refinement, the second threshold approximates the desired operating speed.

It should be understood that while the use of words such as preferable, preferably, preferred or more preferred if utilized in the description above indicate that the feature so described may be more desirable, it nonetheless may not be necessary and embodiments lacking the same may be contemplated as within the scope of the invention, the scope being defined by the claims that follow. In reading the claims, it is intended that when words such as “a,” “an,” “at least one,” or “at least one portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language “at least a portion” and/or “a portion” is used the item can include a portion and/or the entire item unless specifically stated to the contrary.