Method and system for categorizing powertrain torque requests

A method for operating a powertrain of an autonomous vehicle is described. In one example, the autonomous driver may supply a torque request and a torque or power urgency assessment to a powertrain controller. The powertrain controller may monitor vehicle control system parameters based on the driver demand torque and the torque or power urgency assessment.

FIELD

The present description relates to methods and a system for operating a powertrain of a vehicle. The vehicle may include an autonomous driver that requests torque from the powertrain so that the vehicle may reach its intended destination.

BACKGROUND AND SUMMARY

Output of a powertrain of a vehicle may be limited when a human driver requests power from the powertrain so that the possibility of powertrain component degradation may be reduced. For example, if a vehicle is operating in very warm ambient conditions, it may be possible for temperatures of one or more powertrain components to become elevated. A powertrain controller may perform mitigating actions to reduce the temperatures of the one or more powertrain components so that the possibility of the one or more components degrading may be reduced. The mitigating actions may include reducing powertrain output power and/or reducing powertrain efficiency to reduce powertrain component temperature. In addition, it may be desirable for the powertrain controller to take mitigating actions when operating conditions of other powertrain components approach threshold limits. However, there may be vehicle operating conditions where it may be acceptable to continue to operate the powertrain without immediately performing mitigating actions so that some other desirable outcome may be provided via the powertrain.

The inventors herein have recognized the above-mentioned issues and have developed a vehicle operating method, comprising: generating a powertrain torque request and a powertrain torque urgency assessment via an autonomous driver; and adjusting powertrain output torque in response to the powertrain torque request and monitoring one or more control parameters.

By classifying powertrain torque requests according to different urgency levels, it may be possible to provide the technical result of adjusting thresholds at which mitigating actions may be performed and providing higher levels of powertrain output so that desired outcomes may be provided via the powertrain. For example, if it is determined that there is a higher level of urgency to provide requested powertrain output, then one or move powertrain control thresholds may be adjusted such that higher powertrain output levels may be achieved for at least some period of time. Further, powertrain control parameters may be monitored to determine if they exceed the one or more powertrain control thresholds so that it may be determined if the vehicle should return to a service center.

The present description may provide several advantages. Specifically, the approach may provide a desired level of powertrain output that is responsive to urgency of vehicle operating conditions. Further, the approach may provide for returning a vehicle to a service center so that higher levels of powertrain performance may be maintained. In addition, the approach is flexible and it may be applied to a variety of powertrain configurations and control parameters.

DETAILED DESCRIPTION

The present description is related to controlling torque of a powertrain and meeting powertrain desired outcomes. The present description may be useful for operating vehicles that include an autonomous driver (e.g., an automated non-human driver such as an embedded controller that provides commands to a vehicle so that the vehicle moves to a requested destination).FIG.1shows an engine that may be included in a powertrain. The engine may be included in different powertrain configurations as shown inFIGS.2and3. However, the present description also applies to other powertrain configurations that are not shown. For example, the present description is applicable to full electric vehicles that include only electric machines as propulsion sources. A control system block diagram is shown inFIG.4to illustrate example powertrain components and signal flow. Methods for operating a vehicle are shown inFIGS.5and6. Finally, an example vehicle operating sequence according to the methods ofFIGS.5and6is shown inFIG.7.

Referring toFIG.1, internal combustion engine10, comprising a plurality of cylinders, one cylinder of which is shown inFIG.1, is controlled by electronic engine controller12. Engine10is comprised of cylinder head35and block33, which include combustion chamber30and cylinder walls32. Piston36is positioned therein and reciprocates via a connection to crankshaft40. Flywheel97and ring gear99are coupled to crankshaft40. Starter96(e.g., low voltage (operated with less than 30 volts) electric machine) includes pinion shaft98and pinion gear95. Pinion shaft98may selectively advance pinion gear95to engage ring gear99. Starter96may be directly mounted to the front of the engine or the rear of the engine. In some examples, starter96may selectively supply torque to crankshaft40via a belt or chain. In one example, starter96is in a base state when not engaged to the engine crankshaft.

Combustion chamber30is shown communicating with intake manifold44and exhaust manifold48via respective intake valve52and exhaust valve54. Each intake and exhaust valve may be operated by an intake cam51and an exhaust cam53. The position of intake cam51may be determined by intake cam sensor55. The position of exhaust cam53may be determined by exhaust cam sensor57. Intake valve52may be selectively activated and deactivated by valve activation device59. Exhaust valve54may be selectively activated and deactivated by valve activation device58. Valve activation devices58and59may be electro-mechanical devices.

Fuel injector66is shown positioned to inject fuel directly into cylinder30, which is known to those skilled in the art as direct injection. Fuel injector66delivers liquid fuel in proportion to the pulse width from controller12. Fuel is delivered to fuel injector66by a fuel system (not shown) including a fuel tank, fuel pump, and fuel rail (not shown). In one example, a high pressure, dual stage, fuel system may be used to generate higher fuel pressures.

In addition, intake manifold44is shown communicating with turbocharger compressor162and engine air intake42. In other examples, compressor162may be a supercharger compressor. Shaft161mechanically couples turbocharger turbine164to turbocharger compressor162. Optional electronic throttle62adjusts a position of throttle plate64to control air flow from compressor162to intake manifold44. Pressure in boost chamber45may be referred to a throttle inlet pressure since the inlet of throttle62is within boost chamber45. The throttle outlet is in intake manifold44. In some examples, throttle62and throttle plate64may be positioned between intake valve52and intake manifold44such that throttle62is a port throttle. Compressor recirculation valve47may be selectively adjusted to a plurality of positions between fully open and fully closed. Waste gate163may be adjusted via controller12to allow exhaust gases to selectively bypass turbine164to control the speed of compressor162. Air filter43cleans air entering engine air intake42.

During operation, each cylinder within engine10typically undergoes a four stroke cycle: the cycle includes the intake stroke, compression stroke, expansion stroke, and exhaust stroke. During the intake stroke, generally, the exhaust valve54closes and intake valve52opens. Air is introduced into combustion chamber30via intake manifold44, and piston36moves to the bottom of the cylinder so as to increase the volume within combustion chamber30. The position at which piston36is near the bottom of the cylinder and at the end of its stroke (e.g. when combustion chamber30is at its largest volume) is typically referred to by those of skill in the art as bottom dead center (BDC).

During the compression stroke, intake valve52and exhaust valve54are closed. Piston36moves toward the cylinder head so as to compress the air within combustion chamber30. The point at which piston36is at the end of its stroke and closest to the cylinder head (e.g. when combustion chamber30is at its smallest volume) is typically referred to by those of skill in the art as top dead center (TDC). In a process hereinafter referred to as injection, fuel is introduced into the combustion chamber. In a process hereinafter referred to as ignition, the injected fuel is ignited by known ignition means such as spark plug92, resulting in combustion.

FIG.2is a block diagram of a vehicle225including a powertrain or driveline200. The powertrain ofFIG.2includes engine10shown inFIG.1. Powertrain200is shown including vehicle system controller255, engine controller12, electric machine controller252, transmission controller254, energy storage device controller253, brake controller250, autonomous driver201, steering angle controller244, and vehicle human occupant monitor265. The controllers, autonomous driver, and vehicle human occupant monitor may communicate over controller area network (CAN)199. Each of the devices that are coupled to CAN199may provide information to other devices that are coupled to CAN199such as power output limits (e.g., power output of the device or component being controlled not to be exceeded), power input limits (e.g., power input of the device or component being controlled not to be exceeded), power output of the device being controlled, requested steering angle, sensor and actuator data, diagnostic information (e.g., information regarding a degraded transmission, information regarding a degraded engine, information regarding a degraded electric machine, information regarding degraded brakes), powertrain torque requests, powertrain braking requests, human passenger vital signs (e.g., blood pressure, heart rate, respiration rate, etc.), and passenger urgency requests, etc. Further, the vehicle system controller255may provide commands to engine controller12, electric machine controller252, steering angle controller244, transmission controller254, autonomous driver, and brake controller250to achieve autonomous driver and human passenger input requests and other requests that are based on vehicle operating conditions.

For example, in response to an autonomous driver reducing a driver demand torque and vehicle speed, vehicle system controller255may request a desired wheel power or a wheel power level to provide a desired rate of vehicle deceleration. The requested desired wheel power may be provided by vehicle system controller255requesting a first braking power from electric machine controller252and a second braking power from engine controller212, the first and second powers providing a desired driveline braking power at vehicle wheels216. Vehicle system controller255may also request a friction braking power via brake controller250. The braking powers may be referred to as negative powers since they slow driveline and wheel rotation. Positive power may maintain or accelerate driveline and wheel rotation. Vehicle system controller255includes a processor255aand non-transitory memory255b.

In other examples, the partitioning of controlling powertrain devices may be partitioned differently than is shown inFIG.2. For example, a single controller may take the place of vehicle system controller255, engine controller12, electric machine controller252, transmission controller254, and brake controller250. Alternatively, the vehicle system controller255and the engine controller12may be a single unit while the electric machine controller252, the transmission controller254, and the brake controller250are standalone controllers. The autonomous driver201and the vehicle human occupant monitor265may be integrated into the vehicle system controller too.

In this example, powertrain200may be powered by engine10and electric machine240. In other examples, engine10may be omitted. Engine10may be started with an engine starting system shown inFIG.1, or via driveline integrated starter/generator (ISG)240also known as an integrated starter/generator. Driveline ISG240(e.g., high voltage (operated with greater than 30 volts) electrical machine) may also be referred to as an electric machine, motor, and/or generator. Further, power of engine10may be adjusted via power actuator204, such as a fuel injector, throttle, etc.

Bi-directional DC/DC converter281may transfer electrical energy from a high voltage buss274to a low voltage buss273or vice-versa. Low voltage battery280is electrically coupled to low voltage buss273. Electric energy storage device275is electrically coupled to high voltage buss274. Low voltage battery280selectively supplies electrical energy to starter motor96.

An engine output power may be transmitted to an input or first side of powertrain disconnect clutch235through dual mass flywheel215. Disconnect clutch236may be electrically or hydraulically actuated. The downstream or second side234of disconnect clutch236is shown mechanically coupled to ISG input shaft237.

ISG240may be operated to provide power to powertrain200or to convert powertrain power into electrical energy to be stored in electric energy storage device275in a regeneration mode. ISG240is in electrical communication with energy storage device275. ISG240has a higher output power capacity than starter96shown inFIG.1or a BISG. Further, ISG240directly drives powertrain200or is directly driven by powertrain200. There are no belts, gears, or chains to couple ISG240to powertrain200. Rather, ISG240rotates at the same rate as powertrain200. Electrical energy storage device275(e.g., high voltage battery or power source) may be a battery, capacitor, or inductor. The downstream side of ISG240is mechanically coupled to the impeller285of torque converter206via shaft241. The upstream side of the ISG240is mechanically coupled to the disconnect clutch236. ISG240may provide a positive power or a negative power to powertrain200via operating as a motor or generator as instructed by electric machine controller252.

Torque converter206includes a turbine286to output power to input shaft270. Input shaft270mechanically couples torque converter206to automatic transmission208. Torque converter206also includes a torque converter bypass lock-up clutch212(TCC). Power is directly transferred from impeller285to turbine286when TCC is locked. TCC is electrically operated by controller254. Alternatively, TCC may be hydraulically locked. In one example, the torque converter may be referred to as a component of the transmission.

When torque converter lock-up clutch212is fully disengaged, torque converter206transmits engine power to automatic transmission208via fluid transfer between the torque converter turbine286and torque converter impeller285, thereby enabling power multiplication. In contrast, when torque converter lock-up clutch212is fully engaged, the engine output power is directly transferred via the torque converter clutch to an input shaft270of transmission208. Alternatively, the torque converter lock-up clutch212may be partially engaged, thereby enabling the amount of power directly relayed to the transmission to be adjusted. The transmission controller254may be configured to adjust the amount of power transmitted by torque converter212by adjusting the torque converter lock-up clutch in response to various engine operating conditions, or based on a driver-based engine operation request.

Torque converter206also includes pump283that pressurizes fluid to operate disconnect clutch236, forward clutch210, and gear clutches211. Pump283is driven via impeller285, which rotates at a same speed as ISG240.

Automatic transmission208includes gear clutches (e.g., gears1-10)211and forward clutch210. Automatic transmission208is a fixed ratio transmission. Alternatively, transmission208may be a continuously variable transmission that has a capability of simulating a fixed gear ratio transmission and fixed gear ratios. The gear clutches211and the forward clutch210may be selectively engaged to change a ratio of an actual total number of turns of input shaft270to an actual total number of turns of wheels216. Gear clutches211may be engaged or disengaged via adjusting fluid supplied to the clutches via shift control solenoid valves209. Power output from the automatic transmission208may also be relayed to wheels216to propel the vehicle via output shaft260. Specifically, automatic transmission208may transfer an input driving power at the input shaft270responsive to a vehicle traveling condition before transmitting an output driving power to the wheels216. Transmission controller254selectively activates or engages TCC212, gear clutches211, and forward clutch210. Transmission controller also selectively deactivates or disengages TCC212, gear clutches211, and forward clutch210.

Further, a frictional force may be applied to wheels216by engaging friction wheel brakes218. In one example, friction wheel brakes218may be engaged in response to an autonomous driver requesting a braking torque via CAN199and/or in response to instructions within brake controller250. Further, brake controller250may apply brakes218in response to information and/or requests made by vehicle system controller255. In the same way, a frictional force may be reduced to wheels216by disengaging wheel brakes218in response to the autonomous driver cancelling a request for braking torque via CAN199, brake controller instructions, and/or vehicle system controller instructions and/or information. For example, vehicle brakes may apply a frictional force to wheels216via controller250as part of an automated engine stopping procedure.

In response to a request to accelerate vehicle225, vehicle system controller may obtain a driver demand power or power request from the autonomous driver201. Vehicle system controller255then allocates a fraction of the requested driver demand power to the engine and the remaining fraction to the ISG. Vehicle system controller255requests the engine power from engine controller12and the ISG power from electric machine controller252. If the ISG power plus the engine power is less than a transmission input power limit (e.g., a threshold value not to be exceeded), the power is delivered to torque converter206which then relays at least a fraction of the requested power to transmission input shaft270. Transmission controller254selectively locks torque converter clutch212and engages gears via gear clutches211in response to shift schedules and TCC lockup schedules that may be based on input shaft power and vehicle speed. In some conditions when it may be desired to charge electric energy storage device275, a charging power (e.g., a negative ISG power) may be requested while a non-zero driver demand power is present. Vehicle system controller255may request increased engine power to overcome the charging power to meet the driver demand power.

In response to a request to decelerate vehicle225and provide regenerative braking made via the autonomous driver201, vehicle system controller may provide a negative desired wheel power (e.g., desired or requested powertrain wheel power) based on vehicle speed and a braking request made via the autonomous driver201. Vehicle system controller255then allocates a fraction of the negative desired wheel power to the ISG240and the engine10. Vehicle system controller may also allocate a portion of the requested braking power to friction brakes218(e.g., desired friction brake wheel power). Further, vehicle system controller may notify transmission controller254that the vehicle is in regenerative braking mode so that transmission controller254shifts gears211based on a unique shifting schedule to increase regeneration efficiency. Engine10and ISG240may supply a negative power to transmission input shaft270, but negative power provided by ISG240and engine10may be limited by transmission controller254which outputs a transmission input shaft negative power limit (e.g., not to be exceeded threshold value). Further, negative power of ISG240may be limited (e.g., constrained to less than a threshold negative threshold power) based on operating conditions of electric energy storage device275, by vehicle system controller255, or electric machine controller252. Any portion of desired negative wheel power that may not be provided by ISG240because of transmission or ISG limits may be allocated to engine10and/or friction brakes218so that the desired wheel power is provided by a combination of negative power (e.g., power absorbed) via friction brakes218, engine10, and ISG240.

Accordingly, power control of the various powertrain components may be supervised by vehicle system controller255with local power control for the engine10, transmission208, electric machine240, and brakes218provided via engine controller12, electric machine controller252, transmission controller254, and brake controller250.

As one example, an engine power output may be controlled by adjusting a combination of spark timing, fuel pulse width, fuel pulse timing, and/or air charge, by controlling throttle opening and/or valve timing, valve lift and boost for turbo- or super-charged engines. In the case of a diesel engine, controller12may control the engine power output by controlling a combination of fuel pulse width, fuel pulse timing, and air charge. Engine braking power or negative engine power may be provided by rotating the engine with the engine generating power that is insufficient to rotate the engine. Thus, the engine may generate a braking power via operating at a low power while combusting fuel, with one or more cylinders deactivated (e.g., not combusting fuel), or with all cylinders deactivated and while rotating the engine. The amount of engine braking power may be adjusted via adjusting engine valve timing. Engine valve timing may be adjusted to increase or decrease engine compression work. Further, engine valve timing may be adjusted to increase or decrease engine expansion work. In all cases, engine control may be performed on a cylinder-by-cylinder basis to control the engine power output.

Electric machine controller252may control power output and electrical energy production from ISG240by adjusting current flowing to and from field and/or armature windings of ISG as is known in the art.

Transmission controller254receives transmission input shaft position via position sensor271. Transmission controller254may convert transmission input shaft position into input shaft speed via differentiating a signal from position sensor271or counting a number of known angular distance pulses over a predetermined time interval. Transmission controller254may receive transmission output shaft torque from torque sensor272. Alternatively, sensor272may be a position sensor or torque and position sensors. If sensor272is a position sensor, controller254may count shaft position pulses over a predetermined time interval to determine transmission output shaft velocity. Transmission controller254may also differentiate transmission output shaft velocity to determine transmission output shaft acceleration. Transmission controller254, engine controller12, and vehicle system controller255, may also receive addition transmission information from sensors277, which may include but are not limited to pump output line pressure sensors, transmission hydraulic pressure sensors (e.g., gear clutch fluid pressure sensors), ISG temperature sensors, and BISG temperatures, gear shift lever sensors, and ambient temperature sensors. Transmission controller254may also receive requested gear input from gear shift selector290(e.g., a human/machine interface device). Gear shift selector290may include positions for gears1-N (where N is an upper gear number), D (drive), and P (park).

Brake controller250receives wheel speed information via wheel speed sensor221and braking requests from vehicle system controller255. Brake controller250may also receive brake pedal position information from a brake pedal sensor directly or over CAN199. Brake controller250may provide braking responsive to a wheel power command from vehicle system controller255. Brake controller250may also provide anti-lock and vehicle stability braking to improve vehicle braking and stability. As such, brake controller250may provide a wheel power limit (e.g., a threshold negative wheel power not to be exceeded) to the vehicle system controller255so that negative ISG power does not cause the wheel power limit to be exceeded. For example, if controller250issues a negative wheel power limit of 50 N-m, ISG power is adjusted to provide less than 50 N-m (e.g., 49 N-m) of negative power at the wheels, including accounting for transmission gearing.

Autonomous driver201includes a processor201aand non-transitory memory201band it may receive vehicle operating conditions from sensors288. Sensors288may include sensors light detection and ranging sensors (LIDAR), radio ranging sensors (RADAR), cameras, and global positioning system sensors (GPS). Autonomous driver201may select a vehicle travel route based on a destination that is input via vehicle passengers or an external controller. Autonomous driver201may also request driveline or powertrain torque and braking torque amounts in response to road conditions and sensor inputs. In addition, autonomous driver201may also output a powertrain torque urgency assessment level for setting and evaluating powertrain threshold values or levels. Autonomous driver201may issue steering, braking, and torque or power commands to the vehicle system controller255to return a vehicle to a vehicle service center291in response to a request to service the vehicle. Steering controller244may adjust an angle of front wheels245to generate the requested steering angle. Autonomous driver201may communicate the powertrain torque or power request, braking request, and powertrain torque urgency assessment level to vehicle system controller255via CAN199or via direct inputs (e.g., digital inputs).

In one example, the powertrain torque or power urgency assessment level may be an integer value between 1 and 3. However, additional or fewer powertrain torque urgency assessment levels may be provided, if desired. In one example, a powertrain torque or power urgency assessment level of one indicates a lower level of powertrain torque urgency. A powertrain torque or power urgency assessment level of two indicates a medium level of powertrain torque urgency. A powertrain torque or power urgency assessment level of three indicates a high level of powertrain torque urgency. A level one powertrain torque or power urgency level signals the powertrain system that the urgency to deliver the requested powertrain torque is low so that powertrain devices should be operated in a way that they may be expected to operate for their full useful life (e.g., a predetermined vehicle travel distance (150,000 miles) or a predetermined amount of operating time (2500 hours)). A level two powertrain torque or power urgency level signals the powertrain system that the urgency to deliver the requested powertrain torque is medium so that powertrain devices may be operated for a predetermined number of times at elevated performance levels where they may begin to degrade before their full useful life. A level three powertrain torque or power urgency level signals the powertrain system that the urgency to deliver the requested powertrain torque is high so that powertrain devices may be operated for a single time at elevated performance levels where they may begin to degrade in a single use at the elevated performance levels.

The autonomous driver201may select or generate a powertrain torque or power urgency assessment level in response to vehicle operating conditions including urgency requests input to human/machine interface261via human vehicle passengers292, inputs from sensors288, and input from vehicle human occupant monitor265. Vehicle human occupant monitor265may request higher levels of powertrain torque urgency in response to a human's blood pressure, respiration rate, heart beat rate, and other human vital conditions as determined via sensors267including blood pressure sensors, heart beat sensors, and respiration rate sensors. Human/machine interface261may comprise a display panel with touch input for displaying and receiving data and inputs from human passengers292.

Referring now toFIG.3, a second example vehicle driveline system300is shown. The system ofFIG.3includes many of the same powertrain components described inFIG.2. The identification numbers assigned to powertrain components described inFIG.2are carried over intoFIG.3. Specifically, powertrain components identified with a particular number inFIG.2and that are carried over inFIG.3are illustrated with a same number. For example, engine10inFIG.2is the same engine10shown inFIG.3.

The system ofFIG.3includes fewer components than the system that is shown inFIG.2. In particular, the system ofFIG.3does not include an ISG240and its related components. However, vehicle225may be driven via an autonomous driver201and receive input via human/machine interface261and vehicle human occupant monitor as previously described. Further, the system ofFIG.3may operate as previously described with the exception of functions that were attributed to ISG240.

The systems ofFIGS.1-3provides for a vehicle system, comprising: a propulsion source; an autonomous driver; and a controller including executable instructions stored in non-transitory memory to receive a powertrain torque or power request and a powertrain torque or power urgency assessment via the autonomous driver and adjust output torque or power of the propulsion source in response to the powertrain torque or power request and request vehicle service responsive to one or more vehicle control parameters exceeding one or more threshold levels based on the powertrain torque or power urgency assessment. The vehicle system includes where the powertrain torque or power urgency assessment is based on vehicle operating conditions. The vehicle system includes where the powertrain torque or power urgency assessment is based on vital signs of one or more vehicle occupants. The vehicle system includes where the powertrain torque or power urgency assessment is based in input from one or more vehicle occupants. The vehicle system includes where the one or more vehicle control parameters includes a turbocharger speed.

Referring now toFIG.4, a control block diagram that illustrates system components and data flow for the method and system described herein is shown. Portions of block diagram400may be included in the system shown inFIGS.1-3and may perform in cooperation with the method ofFIGS.5and6.

Block diagram400shows autonomous driver201in communication with powertrain control system401, which may include but is not limited to engine controller12, vehicle system controller255, electric machine controller252, transmission controller254, energy storage device controller253, brake controller250, steering angle controller244, and vehicle human occupant monitor265. Further, powertrain control system includes actuators432that may include but are not limited to engine torque actuators204, ISG240, transmission208, brakes218, torque converter206, and other actuators described inFIGS.2and3.

Autonomous driver201sends a powertrain torque or power request and a powertrain torque or power urgency assessment level to the powertrain control system401as indicated by arrows450and452. In one example, vehicle system controller255shown inFIG.2receives these parameters; however, engine controller12and/or other controllers may receive these control parameters from the autonomous driver201. The powertrain torque or power request may be received as a wheel torque or power request or it may be converted to a wheel torque or power request if the torque or power request is a torque or power request at a different powertrain position. For example, if the autonomous driver outputs a transmission input torque or power, the transmission input torque or power may be converted to a wheel torque or power via adjusting the transmission input torque or power for the transmission gear ratio, final drive ratio, and wheel radius at block404. The wheel torque or power is then requested from one or more of the powertrain propulsion sources (e.g., the engine, the electric machine, or a combination of the engine and the electric machine). In one example, the torque or power amounts requested from the powertrain propulsion sources may be a function of battery state of charge, amount of torque or power requested, and other vehicle operating conditions. Block410then outputs control parameter values for powertrain devices that may operate in concert to provide the requested powertrain torque or power. For example, block410may output an electric machine torque to block412. Block410also outputs a present inverter temperature to block414, an electric energy storage device temperature to block416, an electric energy storage device output power to block418, a present turbocharger speed to block420, a present engine air amount to block422, a present catalyst temperature to block424, a present engine speed to block426, a present powertrain noise vibration and harshness assessment to block428, and a present powertrain drivability estimate to block430. The powertrain control parameters input to blocks412-430is not intended to be an exhaustive list of powertrain control parameters and other powertrain control parameters may also be included, if desired. The powertrain control parameters may be related to the requested powertrain torque or power level.

The powertrain torque or power urgency level is input to block406. Block406outputs powertrain thresholds for each of blocks412-430and any other blocks for other powertrain control parameters that may be desired. Block406may output different threshold for each level of powertrain torque or power urgency assessment level. For example, an electric machine torque threshold level for a level one powertrain torque urgency assessment level may be 250 Newton-meters, an electric machine torque threshold level for a level two powertrain torque urgency assessment level may be 255 Newton-meters, and an electric machine torque threshold level for a level three powertrain torque urgency assessment level may be 265 Newton-meters.

Blocks412-430then compare inputs received from block410to threshold levels received from block406. If one of the blocks412-430determines that its input parameter exceeds a level one powertrain torque urgency assessment level threshold, thereby entering operating conditions where the powertrain device may begin to degrade before its full useful life it the powertrain device is operated in the region for a predetermined number of times or for longer than a predetermined time duration (e.g., level two powertrains torque urgency operating conditions for the device), then the block outputs such information to block408. Likewise, if one of the blocks412-430determines that its input parameter exceeds a level two powertrain torque urgency assessment level threshold, thereby entering operating conditions where the powertrain device may begin to degrade upon exceeding the level two powertrain torque urgency assessment level threshold, then the block outputs such information to block408.

For example, if the level one electric machine torque threshold is 250 Newton-meters, the level two electric machine torque threshold is 255 Newton-meters, and the level three electric machine torque threshold is 265 Newton-meters and the present electric machine torque output is 252 Newton-meters, then block412indicates to block408that the electric machine has entered the level two powertrain torque level. However, if the present electric machine torque output is 257 Newton-meters, then block412indicates to block408that the electric machine has entered the level three powertrain torque level.

Block408tracks each time one of blocks412-430enter the level two powertrain torque level. If one of the blocks412-430indicates that a powertrain control parameter has entered level two powertrain conditions more than a predetermined number of times, then block408requests that the autonomous driver proceed to a service station for maintenance. Alternatively, if one of the blocks412-430indicates that a powertrain control parameter has entered level three powertrain conditions once, then block408requests that the autonomous driver proceed to a service station for maintenance.

Blocks412-430may output commands to actuators432so that the torque or power that is requested via the autonomous driver may be provided via the powertrain. Further, if one of the threshold levels of blocks412-430is exceeded, blocks412-430may limit the extent that the threshold may be exceeded. For example, if block406outputs an electric machine torque threshold of 250 Newton-meters based on a powertrain torque urgency assessment level of one, then block416may limit electric machine torque output to less than 255 Newton-meters.

In this way, control parameters of powertrain components may be compared against threshold levels that are associated with powertrain degradation levels. If a powertrain control parameter exceeds a threshold level, then an autonomous driver may be requested to return the vehicle to a service station for maintenance. By operating a vehicle in this way, it may be possible to provide greater powertrain output during vehicle operating conditions where higher vehicle performance carries a higher priority. Further, desirable levels of powertrain output may be provided while extending powertrain component life during operating conditions where higher vehicle performance may be less of a priority.

Referring now toFIG.5, a method for operating an autonomous driver is shown. The method ofFIG.5may operate in cooperation with the method ofFIG.6. At least portions of method500may be implemented as executable controller instructions stored in non-transitory memory of an autonomous driver. Method500may operate in cooperation with the system ofFIGS.1-3. Additionally, portions of method500may be actions taken in the physical world to transform an operating state of an actuator or device.

At502, method502determines vehicle operating conditions including but not limited to distance to the nearest object in the vehicle's forward path, travel route, vehicle speed limit, weather conditions, engine temperature, engine speed, engine load, electric machine speed, electric machine load, present vehicle speed, road grade, and battery state of charge. Method500proceeds to504.

At504, method500method500determines a powertrain wheel torque or power request based on the vehicle travel route and vehicle operating conditions. In one example, method500estimates an amount of wheel torque or power to accelerate or decelerate the vehicle from its present speed to the posted vehicle speed subject to traffic ahead of the vehicle, objects in the vehicle's travel path, road grade, traffic signals, and vehicle drivability constraints. Method500may employ one or more of a rule based controller (e.g., fuzzy controller), machine learning algorithms, pattern recognition algorithms, and/or other known type of controller to generate a powertrain wheel torque or power request. Method500proceeds to506.

At506, method500determines a powertrain torque or power urgency assessment level. The powertrain torque or power urgency assessment level classifies the powertrain torque or power request according to powertrain component degradation that may result from operating the powertrain at the powertrain torque or power urgency assessment level. The powertrain torque urgency assessment level may be an integer value between 1 and 3. However, additional or fewer powertrain torque urgency assessment levels may be provided, if desired. In one example, a powertrain torque urgency assessment level of one indicates a lower level of powertrain torque urgency. Powertrain components may be expected to operate for their full useful life (e.g., a predetermined vehicle travel distance (150,000 miles) or a predetermined amount of operating time (2500 hours)) when the powertrain components are operated at powertrain conditions are at a level one powertrain torque urgency assessment level. A powertrain torque urgency assessment level of one may be identified as a predetermined lower bounded range of powertrain torque output (e.g., from 0 Newton-meters to 350 Newton-meters of torque). A powertrain torque urgency assessment level of two indicates a medium level of powertrain torque urgency. A level two powertrain torque urgency level signals the powertrain system that the urgency to deliver the requested powertrain torque is medium so that powertrain devices may be operated for a predetermined number of times (e.g., 200 occurrences) at elevated performance levels where they may begin to degrade before their full useful life. A powertrain torque urgency assessment level of two may be identified as a predetermined medium bounded range of powertrain torque output (e.g., from 351 Newton-meters to 400 Newton-meters of torque). A powertrain torque urgency assessment level of three indicates a high level of powertrain torque urgency. A level three powertrain torque urgency level signals the powertrain system that the urgency to deliver the requested powertrain torque is high so that powertrain devices may be operated for a single time at elevated performance levels where they may begin to degrade in a single use when operated at the elevated performance levels. A powertrain torque urgency assessment level of three may be identified as a predetermined higher bounded range of powertrain torque output (e.g., above 401 Newton-meters of torque).

In one example, the autonomous driver may select or request a level one powertrain torque urgency assessment level when vehicle human occupants do not specify a powertrain torque urgency assessment level or when the vehicle human occupants specifically request a level one powertrain torque urgency assessment level via the human/machine interface. The autonomous driver may select a level two powertrain torque urgency assessment level when vehicle human occupants specifically request a level two powertrain torque urgency assessment level via the human/machine interface. Likewise, the autonomous driver may select a level three powertrain torque urgency assessment level when vehicle human occupants specifically request a level two powertrain torque urgency assessment level via the human/machine interface. In addition, the autonomous driver may select a level two or three powertrain torque urgency assessment level during specialized vehicle operating conditions. For example, the autonomous driver may select or request a powertrain torque urgency assessment level (e.g., level two or level three) responsive to the vehicle traveling off-road or on a competitive track as determined via the GPS system. Further still, the autonomous driver may select a powertrain torque or power urgency assessment level (e.g., level two or a level three) responsive to vital signs (e.g., heart beat rate, respiration rate, and/or blood pressure) of human occupants in the vehicle. For example, if the human's heat beat is slower than a first threshold or faster than a second threshold, a level two powertrain torque or power urgency assessment level may be requested via the autonomous driver. The autonomous driver may select or request the powertrain torque urgency assessment level in response the human's other vital signs in a similar way. The vital signs of the human occupants may be transferred to the autonomous driver via a human occupant monitor265or the human occupant monitor may specifically signal to the autonomous driver that the vehicle occupant's situation is urgent and that the vehicle's travel destination should be reached in a short amount of time. Method500proceeds to508.

At508, method500requests the torque or power from the powertrain and supplies the powertrain torque or power urgency assessment level to one or more powertrain controllers. In one example, method500requests torque or power from the vehicle system controller and informs the vehicle system controller of the powertrain torque or power urgency assessment level. The autonomous driver may deliver the torque or power request and the powertrain torque or power urgency assessment level via the CAN or via other inputs to the vehicle system controller. In other examples, method500may request torque or power from the engine controller and/or the electric machine controller. Further, method500informs the engine controller and the electric machine controller of the powertrain torque or power urgency assessment level. Method500proceeds to510.

At510, method500judges if the autonomous driver has received a request to service the vehicle. The vehicle system controller, engine controller, electric machine controller, or other powertrain controller may request vehicle service so that the vehicle may continue to operate as expected. The request for service may be received via the CAN or other inputs of the autonomous driver. If method500judges that a request for vehicle service is requested, the answer is yes and method500proceeds to512. Otherwise, the answer is no and method500proceeds to511.

At512, method500sends commands to the steering system, braking system, and powertrain to drive the vehicle to a service station where powertrain components may be inspected and replaced if degradation is observed. Method500may drive the vehicle to the service center after a presently selected destination has been reached by the vehicle. Method500proceeds to exit.

At511, method500sends commands to the steering system, braking system, and powertrain to drive the vehicle to the vehicle's destination. The vehicle's destination may be input via the human/machine interface or directly into the autonomous driver via a human or a Wi-Fi signal. Method500proceeds to exit.

In this way, an autonomous driver may request torque or power from a powertrain. In addition, the autonomous driver may determine a powertrain torque or power urgency assessment level and communicate the powertrain torque or power urgency assessment level to one or more powertrain controllers.

Referring now toFIG.6, a method for operating an autonomous driver is shown. The method ofFIG.6may operate in cooperation with the method ofFIG.5. At least portions of method600may be implemented as executable controller instructions stored in non-transitory memory of a powertrain controller. Method600may operate in cooperation with the system ofFIGS.1-3. Additionally, portions of method600may be actions taken in the physical world to transform an operating state of an actuator or device.

At602, method602determines vehicle operating conditions including but not limited to engine speed, engine load, electric machine speed, electric machine load, present vehicle speed, and battery state of charge. Method600proceeds to604.

At604, method600receives a wheel power or torque request from an autonomous driver. The wheel power or torque request may be received via a CAN or other controller inputs. In some examples, method600may limit the wheel power or torque request responsive to powertrain drivability, powertrain noise, vibration, and harshness. Method600receives the wheel power or torque request and proceeds to606.

At606, method600determines the distribution of the requested wheel torque or power between the vehicle's powertrain propulsion sources. In one example, method600may determine the distribution of wheel torque or power between the vehicle's powertrain propulsion sources via logic in controller memory. For example, if driver demand wheel power or torque is low and state of battery charge is high, method600may allocate all of the torque or power that is requested by the autonomous driver to an electric machine. If driver demand wheel power or torque is low and state of battery charge is low, method600may allocate all of the wheel torque or power that is requested by the autonomous driver to an internal combustion engine. If driver demand wheel power or torque is greater than a first threshold and less than a second threshold, method600may allocate all of the wheel torque or power that is requested by the autonomous driver to the internal combustion engine. If driver demand wheel power or torque is greater than the second threshold, method600may allocate a first portion of the wheel torque or power that is requested by the autonomous driver to an electric machine and a second portion of the wheel torque or power that is requested by the autonomous driver to the internal combustion engine.

Once the requested wheel torque or power is allocated to the powertrain propulsion sources, method600determines the torque or power to be produced by each propulsion source that is allocated a fraction of the requested wheel torque or power. Method600multiplies a wheel torque that is allocated to a particular propulsion source via the present gear ratios between the wheels and the propulsion source and divides the result by the driveline efficiency. For example, if an engine is allocated 75% of a requested wheel torque of 800 Newton-meters (Nm) and the torque converter is locked, method600may determine the requested engine torque via the following equation:

T⁢e⁢n⁢g=Teng_all×Whl_req×G⁢REff_drv
where Teng is the requested engine torque, Teng_all is the fraction of requested wheel torque that is allocated to the engine (e.g., 0.75 for 75%), Whl_req is the requested wheel torque, and GR is the gear ratio including transmission gear ratio and final drive ratio between the wheel and the engine, and Eff_drv is the driveline efficiency between the wheel and the engine. Additional adjustments may be made for the torque converter if the torque converter is unlocked. Torque amounts or power amounts for the other propulsion sources (e.g., electric machines) that have been allocated a fraction of the requested wheel torque may be determined in a similar way.

Method600may also convert one or more of the requested torques or powers into a normalized torque or power request. For example, engine torque may be normalized to an engine load value that may range between 0 and 1, where zero is no engine load and 1 is the engine operating at full engine load (e.g., wide open throttle). The engine load may be determined via dividing the present engine air flow amount by a maximum theoretical engine air flow amount. The engine load may then be converted into a desired engine air flow rate and the engine air flow rate may be converted into a throttle angle. In addition, a turbocharger compressor speed, waste gate position, and compressor bypass valve position may be determined from the desired engine air flow and the present engine speed. Method600may also determine fuel injection amount and desired catalyst temperature for the requested engine torque and present engine speed.

Method600may also determine electric current amount for electric machines and electric energy storage devices. In one example, method600determines an amount of electric current to supply to an electric machine via referencing a table or function that outputs an electric current amount for an electric machine when the table or function is referenced by the electric machine's present speed and the requested torque or power amount of the electric machine. The electric energy storage current output may be equal to the amount of electric current that is consumed by the electric machine to provide the amount of power or torque that is requested from the electric machine. However, if the electric machine is provided with electrical power via the electric energy storage device and another electric machine, then the amount of electric current that is requested output from the electric energy storage device may be less than the amount of electric current that is consumed via the electric machine. Method600proceeds to610after allocating the requested powertrain power or torque to the powertrain propulsion sources.

At608, method600receives a powertrain wheel torque or power urgency assessment level from an autonomous driver. The powertrain wheel torque or power urgency assessment level may be received via a CAN or other controller inputs. Method600may accept and apply the powertrain wheel torque or power urgency assessment level as received from the autonomous driver, or method600may override the received powertrain wheel torque or power urgency assessment level and simply only allow a level one powertrain wheel torque or power urgency assessment level if vehicle service has not been performed at requested intervals or when it has been requested. Method600receives the powertrain wheel torque or power urgency assessment level and proceeds to610.

At610, method600determines powertrain threshold limits and the powertrain threshold limits may include governing powertrain threshold limits and non-governing powertrain threshold limits. The governing powertrain thresholds may be a function of or be based on the received powertrain wheel torque or power urgency assessment level, and the non-governing powertrain threshold limits may be a function of or based on powertrain wheel torque or power urgency levels that are not received via the powertrain controllers from the autonomous driver. The governing and non-governing powertrain threshold limits may include but are not limited to electric machine torque thresholds, engine torque thresholds, electric energy storage device output current thresholds, turbocharger compressor speed thresholds, turbocharger temperature thresholds, inverter electric current output thresholds, inverter temperature thresholds, electric machine temperature thresholds, engine air amount thresholds, catalyst temperature thresholds, powertrain noise, vibration, and harshness thresholds, drivability thresholds, and electric energy storage device temperature thresholds. Of course, additional powertrain thresholds may be provided for other powertrain components that may degrade when the powertrain is operating under level one, level two, or level three powertrain wheel torque or power urgency assessment levels. The powertrain is operated so as to not exceed governing powertrain thresholds.

The governing powertrain thresholds may be such that each powertrain component has less possibility of degrading when the governing powertrain thresholds are based on a level one powertrain wheel torque or power urgency assessment level. The governing powertrain thresholds may be such that each powertrain component has more possibility of degrading when the governing powertrain thresholds are based on a level two powertrain wheel torque or power urgency assessment level. But when the governing powertrain thresholds are based on the level two powertrain wheel torque or power urgency assessment level, the powertrain components have less possibility of degrading as compared to when the governing powertrain thresholds are based on a level three powertrain wheel torque or power urgency assessment level. The governing powertrain thresholds may be such that each powertrain component has a higher possibility of degrading when the governing powertrain thresholds are based on a level three powertrain wheel torque or power urgency assessment level.

For example, a governing engine torque threshold that is based on a level one powertrain wheel torque or power urgency assessment level and that is not to be exceeded by actual engine torque or power may be an engine torque threshold of 300 Nm. However, the governing engine torque threshold that is based on a level two powertrain wheel torque or power urgency assessment level and that is not to be exceeded by actual engine torque or power may be an engine torque threshold of 350 Nm. Further, the governing engine torque threshold that is based on a level three wheel torque or power urgency assessment level and that is not to be exceeded by actual engine torque or power may be an engine torque threshold of 375 Nm. The non-governing engine torque thresholds for level two and level three powertrain wheel torque or power urgency assessment levels are 350 Nm and 375 Nm when the governing engine torque threshold is based on the level one powertrain wheel torque or power urgency assessment level. The non-governing engine torque thresholds for level one and level three powertrain wheel torque or power urgency assessment levels are 300 Nm and 375 Nm when the governing engine torque threshold is based on the level two powertrain wheel torque or power urgency assessment level. The non-governing engine torque thresholds for level one and level two powertrain wheel torque or power urgency assessment levels are 300 Nm and 350 Nm when the governing engine torque threshold is based on the level three powertrain wheel torque or power urgency assessment level. Thus, engine torque thresholds for each powertrain torque or power urgency assessment level may be provided, but the governing engine torque threshold may be based only on the powertrain torque or power urgency assessment level that is presently requested via the autonomous driver. Governing and non-governing thresholds for the other engine control parameters (e.g., electric machine torque, engine torque, electric energy storage device output current, turbocharger compressor speed, etc.) may be adjusted for the powertrain wheel torque or power urgency assessment level in a similar way. Method600proceeds to612.

At612, method600commands the powertrain propulsion sources to deliver the torques determined at606based on the torques they were allocated to provide according to the requested wheel torque. However, if a control parameter, including engine torque and/or electric machine torque, reaches its associated governing threshold level, then mitigating actions may be taken so that the control parameter does not exceed its associated governing threshold level. For example, if a level one powertrain torque or power urgency assessment level is requested and the governing threshold engine torque is 350 Nm, then an engine throttle opening amount and/or fuel injection amount may not be increased once engine torque reaches 350 Nm. In this way, engine control parameters may be restricted to values less than or equal to their associated governing threshold levels. Method600proceeds to614.

At614, method600tracks a number of times that each powertrain control parameter exceeds a threshold that is based on a level one powertrain torque or power urgency assessment. In other words, method600tracks a number of times that each powertrain control parameter enters operating conditions that are allowed when the powertrain torque or power urgency assessment level is two but that are not allowed when the powertrain torque or power urgency assessment level is one. For example, if the powertrain torque urgency assessment level is two, a catalyst threshold temperature is 800° C. for a powertrain torque urgency assessment level of one (e.g., the non-governing catalyst threshold temperature), a catalyst threshold temperature is 850° C. for a powertrain torque urgency assessment level of two (e.g., the governing catalyst threshold temperature), and a temperature of a catalyst cycles between 700° C. and 820° C. two times during a drive cycle, then a total number of times that the catalyst has exceeded the level one threshold catalyst temperature is incremented by two. Method600tracks the number of times that each of the other powertrain control parameters exceeds its threshold that is based on the level one powertrain torque or power urgency assessment level in a similar way.

In addition, method600tracks a number of times that each powertrain control parameter exceeds a threshold that is based on a level two powertrain torque or power urgency assessment. In other words, method600tracks a number of times that each powertrain control parameter enters operating conditions that are allowed when the powertrain torque or power urgency assessment level is three. For example, if the powertrain torque urgency assessment level is three, a catalyst threshold temperature is 800° C. for a powertrain torque urgency assessment level of one (e.g., the non-governing catalyst threshold temperature), a catalyst threshold temperature is 850° C. for a powertrain torque urgency assessment level of two (e.g., the non-governing catalyst threshold temperature), a catalyst threshold temperature is 870° C. for a powertrain torque urgency assessment level of three (e.g., the governing catalyst threshold temperature), and a temperature of a catalyst cycles between 800° C. and 860° C. two times during a drive cycle, then a total number of times that the catalyst has exceeded the level two threshold catalyst temperature is incremented by two. Method600tracks the number of times that each of the other powertrain control parameters exceeds its threshold that is based on the level two powertrain torque or power urgency assessment level in a similar way. Method600proceeds to616.

At616, method600requests service for select powertrain devices by sending a service request to the autonomous driver when one of the powertrain control parameters exceeds its threshold that is based on the level one powertrain torque or power urgency assessment level a predetermined number of times since the time of vehicle manufacture. For example, if turbocharger compressor speed has exceeded a threshold turbocharger compressor speed that is based on the level one powertrain torque or power urgency assessment level a predetermined number of times since the time of vehicle manufacture, method600requests that the autonomous driver proceed to a vehicle service center for service on the turbocharger compressor. Further, method requests service for select powertrain devices by sending a service request to the autonomous driver when one of the powertrain control parameters exceeds its threshold that is based on the level two powertrain torque or power urgency assessment level a single time. Method600proceeds to exit.

In this way, method600may adjust powertrain operation to prevent some powertrain from exceeding threshold levels that are based on powertrain wheel torque or power urgency assessment levels. Further, method600may change threshold levels that govern powertrain operation to meet objectives of vehicle occupants and/or vehicle owners/operators.

Thus, the method ofFIG.6provides for a vehicle operating method, comprising: generating a powertrain torque or power request and a powertrain torque or power urgency assessment via an autonomous driver; and adjusting powertrain output torque or power in response to the powertrain torque or power request and monitoring one or more control parameters. The method further comprises determining an actual total number of times the one or more control parameters exceed one or more threshold levels. The method further comprises adjusting the one or more threshold levels responsive to the powertrain torque or power urgency assessment. The method includes where the powertrain torque or power urgency assessment is based on input provided via one or more vehicle occupants. The method includes where the powertrain torque or power urgency assessment is based on input provided via one or more vehicle systems. The method includes where the one or more vehicle systems monitor one or more vital signs of a human. The method includes where powertrain torque or power output is adjusted via a controller that receives the powertrain torque or power request from the autonomous driver.

The method ofFIG.6also provides for a vehicle operating method, comprising: generating a powertrain torque or power request and a powertrain torque or power urgency assessment via an autonomous driver; adjusting powertrain output torque or power in response to the powertrain torque request and monitoring one or more control parameters; and returning a vehicle to a service center via the autonomous driver responsive to the one or more control parameters exceeding a first threshold level a predetermined number of times after completing a drive cycle in which the first threshold level is exceeded the predetermined number of times. The method further comprises returning the vehicle to the service center via the autonomous driver responsive to the one or more control parameters exceeding a second threshold level a single time after completing the drive cycle in which the second threshold level is exceeded. The method further comprises requesting vehicle service via a powertrain controller. The method further comprises communicating the powertrain torque or power request and the powertrain torque or power urgency assessment from the autonomous driver to a vehicle controller. The method includes where adjusting powertrain output torque or power includes adjusting output torque of an engine. The method includes where adjusting powertrain output torque or power includes adjusting output torque of an electric machine. The method includes where the one or more control parameters includes a temperature of an electric energy storage device. The method includes where the one or more control parameters includes a temperature of a catalyst. In another representation, the method ofFIG.6provides for a vehicle operating method, comprising: generating a powertrain torque or power request and a powertrain torque or power urgency assessment via an autonomous driver; adjusting powertrain output torque or power in response to the powertrain torque or power request and monitoring one or more control parameters; and selecting a powertrain thresholds as a governing threshold responsive to the powertrain torque or power urgency assessment. The method further comprises, comparing a powertrain parameter to the governing threshold. The method further comprises, requesting vehicle service via an autonomous driver in response to the powertrain parameter exceeding a non-governing threshold.

Referring now toFIG.7, a prophetic operating sequence according to the method ofFIG.6is shown. The vehicle operating sequence shown inFIG.6may be provided via the method ofFIG.6in cooperation with the system shown inFIGS.1-3. The plots shown inFIG.7occur at the same time and are aligned in time. The vertical lines at t0-t7represent times of interest during the sequence.

The first plot from the top ofFIG.7is a plot of a powertrain torque request that is received from an autonomous driver by a powertrain controller versus time. The vertical axis represents the powertrain torque request and the powertrain torque request increases in the direction of the vertical axis arrow. The horizontal axis represents time and time increases from the left side of the figure to the right side of the figure. Trace702represents the powertrain torque request.

The second plot from the top ofFIG.7is a plot of a powertrain torque assessment level that is received via a powertrain controller versus time. The vertical axis represents the powertrain torque assessment level. The horizontal axis represents time and time increases from the left side of the figure to the right side of the figure. Trace704represents the powertrain torque assessment level.

The third plot from the top ofFIG.7is a plot of catalyst temperature versus time. The vertical axis represents catalyst temperature and the catalyst temperature increases in the direction of the vertical axis arrow. The horizontal axis represents time and time increases from the left side of the figure to the right side of the figure. Trace706represents the catalyst temperature. Horizontal line750represents a catalyst temperature threshold not to be exceeded for a powertrain torque assessment level of one. Horizontal line752represents a catalyst temperature threshold not to be exceeded for a powertrain torque assessment level of two. Horizontal line754represents a catalyst temperature threshold not to be exceeded for a powertrain torque assessment level of three.

The fourth plot from the top ofFIG.7is a plot of an actual number of times that catalyst temperature has exceeded the catalyst temperature threshold not to be exceeded for a powertrain torque assessment level of one (e.g., the actual number of times that catalyst temperature has entered permissible catalyst temperatures for a powertrain torque assessment level of two). The vertical axis represents the actual number of times that catalyst temperature has exceeded the catalyst temperature threshold not to be exceeded for a powertrain torque assessment level of one. The horizontal axis represents time and time increases from the left side of the figure to the right side of the figure. Trace708represents the actual number of times that catalyst temperature has exceeded the catalyst temperature threshold not to be exceeded for a powertrain torque assessment level of one.

The fifth plot from the top ofFIG.7is a plot of an actual number of times that catalyst temperature has exceeded the catalyst temperature threshold not to be exceeded for a powertrain torque assessment level of two (e.g., the actual number of times that catalyst temperature has entered permissible catalyst temperatures for a powertrain torque assessment level of three). The vertical axis represents the actual number of times that catalyst temperature has exceeded the catalyst temperature threshold not to be exceeded for a powertrain torque assessment level of two. The horizontal axis represents time and time increases from the left side of the figure to the right side of the figure. Trace710represents the actual number of times that catalyst temperature has exceeded the catalyst temperature threshold not to be exceeded for a powertrain torque assessment level of two.

At time t0, the powertrain torque request is low and the powertrain torque assessment level is one. Therefore, the catalyst temperature threshold not to be exceeded for a powertrain torque assessment level of one750is the governing catalyst threshold. The catalyst temperature is well below threshold750so the actual number of times that catalyst temperature has exceeded the catalyst temperature threshold not to be exceeded for a powertrain torque assessment level of one is not incremented. Likewise, the catalyst temperature is well below threshold752so the actual number of times that catalyst temperature has exceeded the catalyst temperature threshold not to be exceeded for a powertrain torque assessment level of two is not incremented.

The powertrain torque request is increased at times t1, t2, and t3without the powertrain torque assessment level increasing. The catalyst temperature is well below threshold750so the actual number of times that catalyst temperature has exceeded the catalyst temperature threshold not to be exceeded for a powertrain torque assessment level of one is not incremented. Additionally, the catalyst temperature is well below threshold752so the actual number of times that catalyst temperature has exceeded the catalyst temperature threshold not to be exceeded for a powertrain torque assessment level of two is not incremented.

At time t4, the autonomous driver increases the powertrain torque assessment level to two and it also increases the requested powertrain torque output. The catalyst temperature increases as the engine's torque output is increased in response to the increase in the powertrain torque request. However, the catalyst temperature remains below threshold750so the actual total number of times that catalyst temperature has exceeded the catalyst temperature threshold not to be exceeded for a powertrain torque assessment level of one is not incremented. Additionally, the catalyst temperature is well below threshold752so the actual total number of times that catalyst temperature has exceeded the catalyst temperature threshold not to be exceeded for a powertrain torque assessment level of two is not incremented.

At time t5, the autonomous driver powertrain torque request is at a higher level and the powertrain torque assessment level remains equal to two. However, the catalyst temperature now exceeds threshold level750so the actual total number of times that catalyst temperature has exceeded the catalyst temperature threshold not to be exceeded for a powertrain torque assessment level of one is now incremented. The catalyst temperature remains below threshold752so the actual total number of times that catalyst temperature has exceeded the catalyst temperature threshold not to be exceeded for a powertrain torque assessment level of two is not incremented. Engine service is not requested because the actual total number of times that catalyst temperature has exceeded the catalyst temperature threshold has not exceeded a predetermined value.

At time t6, the autonomous driver powertrain torque request is increased and the powertrain torque assessment level is increased to a value of three. Therefore, threshold754becomes the governing catalyst threshold. The catalyst temperature begins to increase in response to the engine torque increasing (not shown). The catalyst temperature continues to exceed threshold level750but the actual total number of times that catalyst temperature has exceeded the catalyst temperature threshold not to be exceeded for a powertrain torque assessment level of one is not incremented because catalyst temperature has not been reduced to less than threshold750since time t4. The catalyst temperature remains below threshold752so the actual total number of times that catalyst temperature has exceeded the catalyst temperature threshold not to be exceeded for a powertrain torque assessment level of two is not incremented. Engine service is not requested because the actual total number of times that catalyst temperature has exceeded the catalyst temperature threshold750has not exceeded a predetermined value.

At time t7, engine service is requested because catalyst temperature exceeds threshold752. However, engine service is not requested due to the actual total number of times that catalyst temperature has exceeded the catalyst temperature threshold750has not exceeded a predetermined value. The powertrain torque request levels off at a higher level and the powertrain torque assessment level remains at a value of three.

Thus, vehicle service may be requested in response to a powertrain control parameter exceeding a threshold level that is based on a powertrain torque assessment level of two. Further, vehicle service may be requested in response to a powertrain control parameter exceeding a threshold level that is based on a powertrain torque assessment level of one a predetermined number of times during a vehicle life cycle.

Note that the example control and estimation routines included herein can be used with various engine and/or vehicle system configurations. The control methods and routines disclosed herein may be stored as executable instructions in non-transitory memory and may be carried out by the control system including the controller in combination with the various sensors, actuators, and other engine hardware. The specific routines described herein may represent one or more of any number of processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, various actions, operations, and/or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. One or more of the illustrated actions, operations and/or functions may be repeatedly performed depending on the particular strategy being used. Further, at least a portion of the described actions, operations and/or functions may graphically represent code to be programmed into non-transitory memory of the computer readable storage medium in the control system. The control actions may also transform the operating state of one or more sensors or actuators in the physical world when the described actions are carried out by executing the instructions in a system including the various engine hardware components in combination with one or more controllers.