DE102013208030A1 - Method for determining rotational torque estimation faults and controlling torque during engine operation for hybrid vehicle, involves estimating torque faults after release of clutch based on deviations of actual engine speed profile - Google Patents

Abstract

The method involves releasing a disengaging clutch connected between an internal combustion engine (10) and an electric machine i.e. electromotor, in a vehicle drive strand during a selected engine switching off condition. Rotational torque faults are estimated after release of the disengaging clutch based on deviations of an actual engine speed profile with engine speed set values. The engine speed set values are selected based on an engine torque fault history. The estimated torque faults are located depending on engine actuator settings e.g. ignition timing and boost pressure.

Description

Cross-reference to related applications

The present application takes priority of US Provisional Application Ser. No. 61 / 642,849 filed May 4, 2012, the entire contents of which are incorporated herein by reference for all purposes.

area

The present description relates to a system and method for improving the drivability and fuel economy of a vehicle. The methods may be particularly useful for engines that are selectively connected to an electric machine and a transmission.

General state of the art and abstract

Hybrid vehicles potentially offer improvements in fuel efficiency and vehicle range over non-hybrid vehicles. An example of a hybrid vehicle includes a motor that may be selectively connected to an electric machine and a transmission in accordance with vehicle operating conditions. The engine may be selectively connected to the electric machine and the transmission via an electrically or hydraulically operated disengaging clutch. The disconnect clutch allows the electric machine to provide torque to the vehicle wheels during low torque request conditions without having to operate the engine and without having to provide torque to rotate an engine that does not combust an air-fuel mixture. The disconnect clutch may also be used to restart the engine from a non-rotation condition via the electric machine.

The selective connection of an electric machine to a motor via a disconnect clutch may also involve problems not observed in a non-hybrid vehicle. For example, engine startup may cause vibrations and torque pulses in the vehicle driveline. If the disconnect clutch is operated too abruptly, noises and vibrations may be caused in the vehicle driveline, so that the driver may feel disturbed. Similarly, if the disconnect clutch is released too abruptly, the driver may feel disturbed. Finally, it may be desirable to improve the disconnect clutch operation such that smooth transitions between operating the vehicle without the engine and operating the vehicle with the engine may occur.

The inventors herein have recognized the above-mentioned disadvantages and developed a method of operating a hybrid vehicle that, during selected engine shutdown conditions, enables release of a disconnect clutch connected between an engine and an electric machine in a vehicle driveline and after release of the disengagement clutch estimating torque errors based on deviations of an actual engine speed profile from a commanded engine speed profile at each of a plurality of engine speed setpoints. In this way, torque errors can be determined.

In one example, the engine may be selectively deactivated during an engine shutdown condition, and a disconnect clutch connected between the engine and the remainder of the vehicle driveline having an electric machine, a transmission, and vehicle wheels may be released. Based on the vehicle speed and a pedal position at the time of shutdown, coasting stop may be expected. An engine controller may determine an engine torque commanded prior to release of the clutch. The commanded engine torque may be such that upon release, substantially zero torque is maintained across the disconnect clutch. In the absence of engine torque estimation errors following the release clutch release, the engine may follow an expected speed profile based on the commanded torque. Therefore, based on deviations of the actual engine speed profile from the expected value, torque overestimation and underestimation errors may be determined. In particular, the speed profile may be assessed in a window that is at one or more selected set engine speed values. The speed adjustment values may be determined based on a motor torque error history and correlated with speed adjustment values at which driveline disturbances have occurred. The errors can be determined depending on a motor speed and actuator settings. The detected errors can then may be used to update a torque estimation model and to control engine torque during a subsequent engine restart when the clutch is actuated.

In this way, torque estimation errors can be detected and torque control can be improved. By determining torque errors and updating a torque estimation model, driveline torque disturbances in the powertrain of a hybrid powertrain may be reduced. Furthermore, the approach can improve the driving behavior of the vehicle. In addition, the approach can reduce powertrain wear, thereby increasing the useful life of the powertrain.

The above advantages and other advantages and features of the present description will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.

It will be understood that the summary above is provided to provide in simplified form a selection of concepts that will be further described in the detailed description. It is not intended to identify key features or essential features of the claimed subject matter, the scope of which is defined solely by the claims which follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that eliminate possible disadvantages mentioned above or in any part of the disclosure.

Brief description of the drawings

The advantages described herein are better understood by reading an example of an embodiment, referred to herein as the detailed description, alone or in conjunction with the drawings. Show it:

1 a schematic diagram of an engine;

2 a first exemplary vehicle powertrain configuration;

3 a second exemplary vehicle powertrain configuration;

4 a flowchart for determining torque estimation errors during an engine stop condition and controlling a torque during the subsequent engine operation based on the detected errors;

5 a flow chart of a method for determining torque errors based on deviations in engine speed, engine acceleration, and engine torque from their commanded values;

6 a flow chart of a method for determining torque errors based on deviations in an engine speed profile and an engine acceleration profile of expected profiles at one or more selected engine speed setpoints;

7 an exemplary graph illustrating the determination of torque errors based on the approach 5 represents;

8th to 9 an exemplary graph illustrating the determination of torque errors based on the approach 6 represents.

Detailed description

The present invention relates to the control of a powertrain of a hybrid vehicle. The hybrid vehicle may include a motor and an electric machine as in 1 to 3 shown. The engine may be operated with or without a Crankshaft Integrated Starter / Generator (CISG) integrated into the crankshaft during vehicle operation. In addition, the CISG can be operated with or without the operation of the engine. During selected engine shut-off conditions, when the engine is deactivated and a clutch connecting the engine to the remainder of the vehicle driveline is released, engine torque estimation errors based on deviations of one engine torque estimate may occur Motor speed response and / or a speed response of an electric machine are determined by their expected values after release of the clutch. A motor controller may be configured to control routines such as the routines 4 to 6 to determine torque errors based on deviations of the engine speed profile, deviations of the engine braking profile, etc. from time or a speed-based window after the clutch is released. Examples of determining torque errors based on the deviations after release of the clutch are in 7 to 9 shown. The torque errors may be determined depending on engine settings and actuator settings and may be used to update a torque estimation model. In this way, during subsequent engine operation, engine torque may be better controlled to reduce driveline disturbances.

In relation to 1 becomes an internal combustion engine 10 comprising a cylinder, wherein a cylinder thereof in 1 is shown by the electronic engine control 12 controlled. The motor 10 has a combustion chamber 30 and cylinder walls 32 with a piston 36 That is arranged in and with the crankshaft 40 is connected. The flywheel 97 and the ringwheel 99 are with the crankshaft 40 connected. The starter 96 has a pinion shaft 98 and a pinion gear 95 on. The pinion shaft 98 can the pinion gear 95 selectively advance to the ring gear 99 to engage. As shown, the combustion chamber 30 with the intake manifold 44 and the exhaust manifold 48 via a respective inlet valve 52 and exhaust valve 54 connected. Each intake and exhaust valve may be from an intake cam 51 and an exhaust cam 53 be operated. The position of the intake cam 51 can through the intake cam sensor 55 be determined. The position of the exhaust cam 53 can through the exhaust cam sensor 57 be determined.

As shown, the fuel injector is 66 positioned in such a way that it injects fuel directly into the cylinder 30 injects, as the skilled person is known as direct injection. Alternatively, fuel may be injected into an inlet port, as known to those skilled in the art as port injection. The fuel injector 66 gives liquid fuel in proportion to the pulse width of the signal FPW of the controller 12 from. Fuel is delivered to the fuel injector 66 from a fuel system (not shown) having a fuel tank, a fuel pump and a fuel feeder (not shown). The fuel injector 66 is powered by a driver 68 supplied to the controller 12 responding. In addition, the intake manifold 44 in conjunction with an optional electronic throttle 62 shown a position of the throttle 64 adjusts to a flow of air from the air inlet 42 to the intake manifold 44 to control. In one example, a low pressure direct injection system may be used wherein the fuel pressure may be increased to about 20 to 30 bar. Alternatively, a two-stage high pressure fuel system may be used to generate higher fuel pressures.

In response to the controller 12 provides the distributorless ignition system 88 the combustion chamber 30 through the spark plug 92 a spark ready. As shown, the UEGO (Universal Exhaust Gas Oxygen) sensor 126 with the exhaust manifold 48 upstream of the catalyst 70 connected. Alternatively, the UEGO sensor 126 be replaced by a two-state exhaust gas oxygen sensor.

The catalyst 70 may have multiple catalyst carriers ("bricks") in one example. In another example, multiple emission control devices, each having multiple catalyst carriers, may be used. The catalyst 70 may be a three-way catalyst in one example.

The control 12 is in 1 as a conventional microcomputer, comprising: a microprocessor unit 102 , Input / output connections 104 , a read only memory 106 , a read / write memory 108 , a keep-alive memory 110 and a conventional data bus. As shown, the controller receives 12 In addition to the signals explained above, various signals from sensors connected to the engine 10 and include: the engine coolant temperature (ECT) from the temperature sensor 112 that with the cooling sleeve 114 connected is; a position sensor 134 that with an accelerator pedal 130 for detecting one of the foot 132 applied force is connected; a measurement of the engine manifold pressure (MAP) of the pressure sensor 122 that with the intake manifold 44 connected is; a motor position sensor of a Hall effect sensor 118 , which is the position of the crankshaft 40 detected; a measurement of the air mass entering the engine through the sensor 120 ; and a measurement of the throttle position of the sensor 58 , Further, the air pressure (sensor not shown) for processing by the controller 12 be recorded. In a preferred aspect of the present description, the engine position sensor generates 118 a predetermined number of evenly spaced pulses every revolution of the crankshaft from which the engine speed (RPM) can be determined.

In some examples, the engine may be connected to an electric motor / battery system in a hybrid vehicle, as in FIG 2 and 3 shown. Further, in some examples, other engine configurations, such as a diesel engine, may be used.

During operation, each cylinder in the engine 10 The cycle includes the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke. During the intake stroke, the exhaust valve closes 54 in general and the inlet valve 52 opens. Air gets into the combustion chamber 30 through the intake manifold 44 taken in and the piston 36 moves to the bottom of the cylinder, thus increasing the volume in the combustion chamber 30 to increase. The position at which the piston 36 near the bottom of the cylinder and at the end of its stroke is (for example, if the volume of the combustion chamber 30 is the largest) is typically referred to by the expert as Bottom Dead Center (BDC). During the compression stroke, the inlet valve 52 and the exhaust valve 54 closed. The piston 36 moves to the cylinder head, so the air in the combustion chamber 30 to condense. The point where the piston is 36 at the end of its stroke and closest to the cylinder head (eg when the volume of the combustion chamber 30 is the smallest) is typically referred to by the expert 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 becomes a spark plug by known ignition means 92 ignited, resulting in combustion. During the expansion stroke, the expanding gases push the piston 36 back to bottom dead center. The crankshaft 40 converts the piston movement into a torque of the rotary shaft. Finally the exhaust valve opens 54 during the exhaust stroke to the burned air-fuel mixture to the exhaust manifold 48 and the piston returns to top dead center. It should be understood that the above illustration is intended to be exemplary only and that the intake and exhaust valve opening and / or closing times may vary to provide positive or negative valve overlap, late intake valve closing, or various other examples.

2 is a block diagram of a vehicle powertrain 200 , The powertrain 200 can from the engine 10 be driven. The motor 10 can be started with a motor start system that works in 1 represented by the CISG 240 , Furthermore, the engine can 10 a torque through the torque actuator 204 as a fuel injector, throttle, etc. create or adjust.

An engine output torque may be applied to an input side of the dual mass flywheel 232 be transmitted. The engine speed, as well as the position of the dual mass flywheel input side and the speed can be determined using the engine position sensor 118 be determined. The dual mass flywheel 232 may include springs and separate masses (not shown) for damping powertrain torque disturbances. As shown, output side of the dual mass flywheel 232 with the input side of the disconnect clutch 236 mechanically connected. The disconnect clutch 236 can be operated electrically or hydraulically. A position sensor 234 is on the disengagement clutch side of the dual mass flywheel 232 arranged to the output position and speed of the dual-mass flywheel 232 capture. The downstream side of the disconnect clutch 236 is with the CISG input shaft 237 shown mechanically connected.

The CISG can be operated to the drivetrain 200 To provide a torque or convert a powertrain torque into electrical energy stored in the storage device 275 stored for electrical energy. The storage device 275 for electrical energy may be a battery, a capacitor or an inductor. The downstream side of the CISG 240 is with the impeller 285 of the torque converter 206 over the wave 241 mechanically connected. The upstream side of the CISG is with the disconnect clutch 236 mechanically connected. The torque converter 206 has a turbine 286 on to torque to the shaft 270 issue. The wave 270 connects the torque converter 206 mechanically with the automatic transmission 208 , The torque converter 206 also has a torque converter lockup lockup clutch 212 (TCC). The torque is from the impeller 285 directly on the turbine 286 transmitted when the TCC is locked. The TCC is controlled by the controller 12 electrically operated. Alternatively, the TCC can be hydraulically locked. In one example, the torque converter may be referred to as a component of the transmission.

The torque converter turbine speed and position may be determined by the position sensor 239 be determined. In some examples, the reference numerals 238 and or 239 Be torque sensors or a combination of position and torque sensors.

When the torque converter lockup clutch 212 fully disengaged transmits the torque converter 206 an engine torque via fluid transfer between the torque converter turbine 286 and the torque converter impeller 285 on the automatic transmission 208 so that a torque multiplication is possible. In contrast, when the torque converter lock-up clutch 212 is fully engaged, the engine output torque through the torque converter clutch directly to an input shaft (not shown) of the transmission 208 transfer. Alternatively, the torque converter lock-up clutch 212 be partially engaged, so that the transmitted directly to the transmission torque amount can be adjusted. The control 12 can be configured to adjust the amount of torque supplied by the torque converter 212 by adjusting the torque converter lock-up clutch in response to various engine operating conditions or based on an engine operating request from the driver.

The automatic transmission 208 has gear couplings (eg gears 1 to 6) 211 and a forward clutch 210 on. The gear couplings 211 and the forward clutch 210 can be selectively engaged to power a vehicle. The torque output of the automatic transmission 208 can turn on the wheels 216 be transmitted to the vehicle via the output shaft 260 drive. More precisely, the automatic transmission 208 prior to transmitting output drive torque to the wheels 216 an input drive torque at the input shaft 270 transmitted in response to a vehicle travel condition.

Furthermore, a frictional force on the wheels 216 be applied by the wheel brakes 218 be operated. In one example, the wheel brakes 218 in response to the driver stepping on a brake pedal (not shown). In other examples, the controller may 12 or a controller with the controller 12 is linked, press wheel brakes. In the same way, a frictional force on the wheels 216 be reduced by the wheel brakes 218 in response to the driver taking his foot off a brake pedal, be released. Furthermore, vehicle brakes on the controller 12 a friction force on the wheels as part of an automated engine stop procedure 216 exercise.

A mechanical oil pump 214 can with the automatic transmission 208 in fluid communication to provide hydraulic pressure to various clutches such as the forward clutch 210 , the gear clutches 211 and / or the torque converter lock-up clutch 212 engage. The mechanical oil pump 214 can be in accordance with the torque converter 206 can be actuated and controlled by the rotation of the motor or CISG over, for example, the input shaft 241 are driven. In this way, can be in the mechanical oil pump 214 increase hydraulic pressure as engine speed and / or CISG speed increases, and may decrease with decrease in engine speed and / or CISG speed.

The control 12 can be configured to receive inputs from a motor 10 to receive, as more detailed in 1 and, accordingly, may control torque output of the engine and / or operation of the torque converter, transmission, CISG, clutches, and / or brakes. For example, engine torque output may be controlled by adjusting a combination of spark timing, fuel pulse width, fuel pulse times, and / or air charge by controlling throttle opening and / or valve timing, valve lift, and boost for turbocharger or supercharger engines. In the case of a diesel engine, the controller 12 control engine torque output by controlling a combination of fuel pulse width, fuel pulse times, and air charge. In either case, cylinder-level engine control may be performed to control engine torque output. The control 12 may also control the torque output and the generation of electrical energy from the CISG by adjusting the current flowing to and from the field and / or armature windings of the CISG, as known in the art.

If the idle stop conditions are met, the controller may 42 initiate an engine shutdown by blocking fuel and ignition to the engine. However, the engine may continue to rotate in some examples. Further, to maintain the amount of torsion in the transmission, the controller 12 Rotary elements of the transmission 208 on a housing 259 of the transmission and thus set to the frame of the vehicle. In particular, the controller 12 one or more transmission clutches such as the forward clutch 210 engage and the engaged transmission clutch (s) on the transmission housing 259 and the vehicle frame as described in US Patent Application No. 12 / 833,788 "METHOD FOR CONTROLLING TO ENGINE THAT MAY BE AUTOMATICALLY STOPPED", which is incorporated herein by reference for all purposes. A transmission clutch pressure may vary (eg increased) to adjust the engagement state of a transmission clutch and provide a desired Getriebetorsionsmenge.

A wheel brake pressure may also be adjusted during engine shutdown based on the transmission clutch pressure to assist in setting the transmission while reducing torque transmitted through the wheels. More precisely, by pressing the wheel brakes 218 upon engagement of one or more engaged transmission clutches, opposing forces are exerted on the transmission and thus on the drive train so that the gears are kept in active engagement and potential torsional energy in the gear train without moving the wheels. In one example, the wheel brake pressure may be adjusted such that the actuation of the wheel brakes is coordinated with the locking of the engaged transmission clutch during engine shutdown. As such, by adjusting the wheel brake pressure and the clutch pressure, the amount of torsion retained in the transmission when the engine is off can be adjusted.

If restart conditions are met and / or a vehicle operator wants to start the vehicle, the controller may 12 Reactivate the engine by resuming cylinder combustion. As further in relation to 4 to 9 explained, the engine can be started in various ways.

In relation to 3 A second exemplary vehicle powertrain configuration is illustrated. Many of the elements in the powertrain 300 similar to the elements of the powertrain 200 and use corresponding reference numerals. Therefore, for the sake of brevity, the description of the elements that 2 and 3 have shared, left out. The description of 3 is restricted to elements that are different from the elements 2 are.

The powertrain 300 has a gearbox 308 with two clutches and two intermediate shafts (dual clutch - dual layshaft transmission). The gear 308 is essentially an automatically operated manual transmission. The control 12 actuates the first clutch 310 , the second clutch 314 , and a switching mechanism 315 between the gears (eg 1st to 5th gears) 317 select. The first clutch 310 and the second clutch 314 Can be selectively opened and closed between the gears 317 switch. The output shaft 260 puts the wheels 216 from the transmission 308 a torque ready.

Applicants have recognized that for hybrid powertrains with a disengaging clutch (in 2 with the reference number 236 shown) may be important in the engine output between the engine and the electric machine (or CISG) that the engine can be quickly and seamlessly connected and disconnected. More specifically, the responsiveness to connect the engine when the engine is to accelerate the vehicle according to driver-requested input is particularly important. Likewise, a seamless transition is desired to allow transparent mode transitions. To this end, the powertrain must be capable of robustly triggering engine torques near zero at various engine speeds.

T_Mot:

Motorausgabedrehmoment, Summe der angegebenen, Reibung und Pumpen (Iα-Effekt nicht eingeschlossen), Nm

I_Mot:

Trägheit aller Komponenten, die sich mit dem Motor drehen, Nm/(U/min/s)

N_Mot:

Motordrehzahl, U/min

N_EM:

Drehzahl der elektrischen Maschine, U/min

α_Mot:

Motorbeschleunigung =

U/min/s

α_EM:

Beschleunigung der elektrischen Maschine =

U/min/s

T_Kap:

Ausrückkupplungskapazität, Nm

T_Kupplung:

Ausrückkupplungsdrehmoment (das tatsächlich angewendet wird), Nm Ausgabe der Kupplung, Eingabe in elektrische Maschine und Drehmomentwandler dieses Drehmoment ist negativ, wenn die Kupplung den Motor hochzieht

T_net:

”Netto”-Motordrehmoment bei Kupplungseingabe (was von einem Drehmomentsensor gemessen würde) = T_Mot – I_Mot·α_Mot

For example, when the disconnect clutch is actuated or released, a change in torque from the clutch to the driveline and powertrain (referred to herein as T _clutch ) is proportional to the clutch torque capacity used to maintain the engine speed and speed of the electric machine ( because the speeds on both sides of the clutch are the same when the clutch is locked). Disregarding the dynamics of the high-frequency damper / flywheel, the following parameters and their respective units are defined:

T _Mot :

Engine output torque, sum of specified friction and pumps (Iα effect not included), Nm

I _Mot :

Inertia of all components that rotate with the engine, Nm / (rpm)

N _Mot :

Engine speed, rpm

N _EM :

Speed of electric machine, rpm

α _Mot :

Motor acceleration =

U / min / sec

α _EM :

Acceleration of the electric machine

U / min / sec

T _cape :

Release clutch capacity, Nm

T _coupling :

Disconnect clutch torque (actually applied), Nm clutch output, input to electric machine and torque converter This torque is negative when the clutch is pulling the engine up

T _net :

"Net" engine torque at clutch input (which would be measured by a torque sensor) = T _Mot - I _Mot · α _Mot

When the clutch grinds, the following applies: T = T _{clutch Cape} · sign (N _Mot - N _EM) T _net = T _coupling

When the clutch is locked, the following applies: α _Mot = α _EM , N _Mot = N _EM T _clutch = T _net = T _Mot - I _Mot · α _Mot , restricted by | T _coupling | ≤ T _chap

Upon release of the disconnect clutch, the clutch capacity is reduced to zero from a value high enough to keep it locked. If the system goal is to minimize changes in T _clutch due to clutch release, where T _clutch drops to zero when T _Cape reaches zero, then just before and during clutch release, the following should apply: T _net = 0 T _Mot = I _Mot · α _Mot = I _Mot · α _EM

In other words, the motor torque (without Iα effect) should be proportional to the acceleration of the electric machine. If the speed of the electric machine is constant during clutch release, then the engine torque should be zero.

In comparison, upon actuation of the clutch, the clutch capacity is increased from zero to a high value to ensure that it will remain locked. If the system goal is to minimize T _clutch changes due to the clutch actuation, the following should apply shortly before and during clutch actuation:
N _Mot = N _EM so that the motor acceleration required to lock the clutch is minimized T _Mot = I _Mot · α _Mot = I _Mot · α _EM In other words, the motor torque (without Iα effect) should be proportional to the acceleration of the electric machine. If the speed of the electric machine is constant during clutch operation, then the engine torque should be zero.

It is desirable for both clutch actuation and clutch release to robustly actuate engine torque at the desired height in proportion to the acceleration of the electric machine. This operation of engine torque must be responsive to noise factors such as inter-part variation, engine speed when the clutch is actuated or released (eg in the range of ~ 600 to 3000 rpm), internal engine friction, engine friction changes over time due to engine wear, variations in engine torque Oil viscosity due to temperature, type of oil, oil age, varying air pressure (based on its influence on engine pump losses), air charge estimation error to be robust.

Therefore, at the time of actuation or release of the disengagement clutch, the engine torque must be properly actuated to minimize torque disturbances. When this is achieved, it changes Engine acceleration due to clutch release not. However, if too high or too low a torque is delivered at the time of clutch release, then the engine acceleration changes or is other than the expected acceleration based on the estimated engine torque. This would indicate a torque estimate (or history) error.

Applicants have accordingly recognized that by comparing the expected engine speed response (including an engine speed or acceleration / deceleration profile) to clutch release with the actual engine speed response, torque estimation errors may be determined and used to update a motor torque estimation model. This allows torque errors to be detected and applied to subsequent engine operations such as during clutch actuation on a subsequent engine restart and during clutch release on a subsequent engine shutdown.

In relation to 4 FIG. 10 is a flowchart of an example method of operating a vehicle powertrain and determining torque errors with the methods. FIG 5 to 6 shown. The procedure off 4 can be used as executable instructions in nonvolatile memory of the controller 12 saved as in 1 to 3 shown.

at 402 determines the procedure 400 Operating conditions. Operating conditions include, but are not limited to, torque request, engine speed, engine torque, speed and torque of an electric machine or CISG, vehicle speed, ambient temperature and pressure, and battery state of charge. The torque request may be from the accelerator pedal 130 and the controller 12 out 1 be derived. The procedure 400 go to 402 continue after the operating conditions are determined.

at 402 can be determined whether engine stop conditions have been met. An engine stop can be requested via an operator key or pushbutton input, the only function of which is the request for a motor start. Alternatively, an engine stop may be by the controller 12 automatically requested based on operating conditions. For example, engine stop may be requested in response to the desired powertrain torque being less than a threshold, vehicle speed less than a threshold speed, or engine torque less than a threshold torque. As another example, the controller 12 request an engine stop in response to a driver actuating a vehicle brake pedal or in response to a battery state of charge (higher than a threshold). In this way, a request to stop the engine may be initiated by inputs having functions other than just requesting engine stop. In still other examples, an engine stop may be requested automatically in response to one of the following idle stop conditions being met. These include, for example, that the engine is combusting, the battery state of charge is above a threshold (eg, more than 30%), the vehicle speed is above a threshold, no air conditioning request is made, and the engine temperature is above a threshold, the emission control device temperature is above a threshold (eg, above a firing temperature), the driver requested torque is below a threshold, the electrical load is below a threshold, and so on become. That is, it can be provided that the engine is not turned off.

After confirming that the engine stop conditions have been met, is at 406 determines if an engine coast stop is expected. In one example, an engine coast stop or vehicle idle may be expected if the brake pedal and accelerator pedal are not depressed and the vehicle is moving. In another example, an engine coast stop may be expected based on a specified desired duration to completely stop the engine. For example, when the engine stop conditions are met, a vehicle speed may be estimated, and it may be determined whether the vehicle speed is above a threshold speed. The threshold speed may correspond to a vehicle inertia that may not be able to sustain a vehicle idle for a substantial amount of time, with a potential vehicle standstill imminent. Thus, when the vehicle speed is above the threshold, an engine coasting stop may occur that provides fuel economy benefits. In yet another example, the engine coasting stop may be expected based on traffic or geographic information related to the environment of the vehicle as determined by a vehicle navigation system. For example, if the vehicle is driven in a city that frequently starts and stops, an engine coast stop may be unexpected.

If a coasting stop is expected then you can 408 the coasting stop torque error estimation conditions are confirmed. This may include confirming that the vehicle speed is above a minimum threshold speed but below a maximum threshold speed, that the battery state of charge is below a threshold (such that the regenerative braking power may be directed from the electric machine to the battery during the coasting stop) Engine torque is below a threshold (such that sufficient torque capacity is present in the engine with respect to the negative torque generated during the coastdown stop) that the fuel level in a vehicle fuel tank is higher than a threshold that the transmission is in required gear (otherwise may need to be switched before a torque error can be estimated), etc. included.

If the coasting stop torque estimation conditions are not met, then the routine includes 412 selectively deactivating the engine by shutting off fuel and spark to the engine and releasing a disconnect clutch connected between the engine and an electric machine (such as an electric motor or a CISG) in the vehicle drive shaft. Thereafter, the controller may cause the engine to coast down, but may not estimate torque errors after clutch release during the coast down stop. In one example, a decelaration fuel shut-off (DFSO) operation may be performed to shut off fuel delivery to the engine while the engine continues to rotate. Specifically, after initiation of a DFSO operation, fuel injection to the cylinders is cut off. The engine then gradually turns to hibernate.

If the coasting stop torque estimation conditions are satisfied, then the routine includes 414 the selective deactivation of the engine. In addition, a disconnect clutch connected between the engine and an electric machine (such as an electric motor or a CISG) in the vehicle drive shaft may be released. Optionally, to maintain a constant torque at the vehicle wheels, an electric motor torque can be increased. As in 5 to 6 The controller may then estimate a torque error after disengagement of the disengagement clutch (but before deactivation of fuel delivery to the engine) based on deviations in one or more of torque, engine speed, engine acceleration / deceleration from their desired values at the time of clutch release. The engine speed response may be assessed at each of a plurality of engine speed setpoints.

Additionally, torque errors based on a deviation of engine speed and engine acceleration may be estimated from the expected profile, for example, at each of a plurality of engine speed setpoints. In one example, the machine is the CISG. In another example, the engine is an electric motor of the hybrid vehicle powertrain. As in 5 to 6 For example, the estimated errors may be determined depending on engine settings such as engine speed and actuator settings such as throttle angle, boost pressure, cam timing, valve timing, and so on. The detected errors can be used to update a torque estimation model.

If, back at 406 , no coasting stop is expected, then at 410 Non-coasting stop torque error estimation conditions are confirmed. These include confirming that a restart due to a change of heart is not expected or not requested. If a restart is to be expected due to a change of mind of a driver, the torque error estimation may be made using the approach 6 not be carried out. If the driver changes his mind requesting an engine restart directly from the engine stop condition, the controller may be configured not to perform the engine torque error estimate (or to stop it immediately if the restart is requested due to a change in sense during the torque error estimation) and a full engine stop to cause a subsequent engine restart in response to the driver's change of mind.

If the no coast stop torque estimation conditions are not met, then the routine continues to increase 412 , Here, the routine includes selectively deactivating the engine by shutting off fuel and spark to the engine and releasing a disconnect clutch connected between the engine and an electric machine (such as an electric motor or a CISG) in the vehicle drive shaft. Thereafter, the controller may cause the engine to coast down (eg, a faster stop), but may not estimate torque errors after clutch release during the coast down stop.

If non-coasting stop torque estimation conditions are met, then the routine continues to increase 414 , wherein the motor is selectively deactivated. In addition, a disconnect clutch connected between the engine and an electric machine (such as an electric motor or a CISG) in the vehicle driveline may be released or released. Optionally, to maintain a constant torque at the vehicle wheels, an electric motor torque can be increased. As in 5 to 6 The controller may then estimate a torque error upon release of the disconnect clutch based on deviations in one or more of torque, engine speed, and engine acceleration / deceleration from its desired values upon clutch release. In particular, the controller may estimate torque errors based on deviations of the actual engine speed profile from the commanded engine speed profile at each of a plurality of engine speed setpoints.

A number of engine speed setpoints at which the engine speed response is checked may vary based on whether the engine stop was a coast stop or a no coast stop. In particular, a larger number of engine speed set values for torque errors may be judged when the engine is coast down (due to the relatively longer time to full engine rest state), whereas a smaller number of engine speed set values may be judged for torque errors the engine is subjected to a non-coasting stop (due to the relatively shorter time to complete engine dormancy).

From 414 The routine can continue to 416 go, taking the procedure 400 judges whether engine restart conditions have been met or not and whether engine start is desired. An engine start can be requested via an operator key or a pushbutton input, the only function of which is the request for an engine start. Alternatively, an engine restart from the controller 12 automatically requested based on operating conditions. For example, the controller 12 request engine start in response to a driver releasing a vehicle brake pedal or in response to a battery state of charge. In this way, a request to restart the engine may be initiated by inputs having functions other than just requesting engine startup. If the procedure 400 judges that an engine restart is requested, the procedure goes 400 further to 420 , Otherwise, the procedure goes 400 further to 418 wherein the engine is maintained in the shut-off condition (or idle-stop condition) until the engine restart conditions are met.

at 420 For example, the engine may be selectively reactivated in response to engine restart conditions being met (eg, by resuming spark and fueling). In some embodiments, the engine may be cranked using a starter, such as a starter, with a lower torque output than that of the CISG. In another example, the engine may be started via the CISG while the lower torque capacity starter remains disabled. After reactivating the engine, the disengagement clutch can be actuated. In addition, engine torque may be commanded at or just prior to actuation of the clutch to enable a seamless transition, wherein the engine torque command is based on the detected torque errors and the updated torque estimation model.

In this way, torque estimation errors can be determined so that torque errors can be reduced over time. Thereby, the torque control can be improved, in particular during the operation and release of a clutch in a hybrid vehicle drive train.

Regarding 5 is an exemplary process 500 for determining torque estimation errors based on deviations in engine speed and acceleration upon release of the clutch during an engine shutdown. The procedure off 5 can look like part of the routine 4 as in 414 be applied. An exemplary graph illustrating the determination of torque errors through the approach 5 is explained in 7 shown.

at 501 the method includes confirming that an engine coast stop has been requested. The procedure 500 out 5 can only be done during a motor coast stop. at 502 For example, the method after confirming includes attempting to provide zero torque in a disengagement clutch (after clutch release) wherein the disengagement clutch mechanically connects a motor and an electric machine. In one example, the routine includes determining an engine torque command that provides substantially zero torque in the clutch after clutch release, and commanding the determined torque command during engine stop conditions immediately prior to clutch release.

After that, the routine includes 504 selectively deactivating the engine and reducing the disengagement clutch capacity (to gradually release the disconnect clutch) while maintaining the determined engine torque command during engine deceleration. After that can at 506 confirmed that the disengagement clutch has been released. For example, it can be confirmed that the clutch capacity of the disengaging clutch is below a threshold or at a minimum capacity. After confirming that the disconnect clutch has been released, the procedure at 508 estimating one or more of an engine speed, an engine acceleration / deceleration, and a speed of an electric machine and an engine acceleration / deceleration for a time since the clutch release.

at 510 For example, an expected engine speed, an engine acceleration / deceleration, an electrical machine speed, and an engine acceleration / deceleration for the time period since the disengagement clutch release may be determined based on the commanded engine torque. In one example, the particular engine torque command may be selected such that the engine is decelerated at an expected deceleration rate or with an expected engine speed response following release of the clutch. Similarly, the particular engine torque command may be selected to provide an expected engine speed profile or rate after the release clutch is released.

at 512 The actual engine speed and engine speed (at 508 estimated) with the expected values (at 510 determined). If the actual values match the expected values, then 514 no motor torque error can be determined. In comparison, if the actual value does not match the expected value, the routine determines at 516 a motor torque error based on a deviation of the actual values from the estimated values. More specifically, the engine controller estimates a torque error upon release clutch release based on a deviation in one or more of engine speed, engine acceleration / deceleration, engine speed, engine acceleration / deceleration, and engine torque from their expected or commanded clutch release values. Therefore, the routine includes determining a motor torque error based on a speed response of the motor and / or the electric machine after the disengagement clutch is released.

The controller may determine whether the estimated error due to overestimation or underestimation of engine torque occurred based on the direction of the deviation. In one example, determining a torque error based on the engine speed response includes estimating the engine torque error based on a deviation of the actual deceleration rate of the decelerating engine from the expected deceleration rate. If the engine torque command is maintained after disengagement of the disengagement clutch, and if the torque command coincided correctly with the zero torque in the disengagement clutch, then the speed of the electric machine should remain constant after clutch release (or within a threshold of the previous speed, such as within 10 RPM). while the engine should maintain its current speed or should decelerate at a constant, low rate prior to clutch release. In this way, a motor torque error is determined in response to a change in engine speed and a change in engine speed or deceleration rate after clutch release (compared to prior to clutch release). The determining may further include determining an engine torque overestimation error when the engine decelerates slower than the expected deceleration rate (or engine speed is higher than the expected engine speed) and determining an engine torque underestimation error when the engine decelerates faster than expected Deceleration rate (or the engine speed is lower than the expected speed).

at 518 Torque errors can be determined depending on motor settings and actuator settings. For example, the torque errors can be determined as a function of the engine speed. As another example, the torque errors may be determined as a function of throttle angle, valve timing, spark timing, cam timing, boost pressure, manifold airflow, etc. In one example, the controller may update the errors in a look-up table that stores the estimated torque errors depending on the engine and actuator settings.

at 520 The routine includes updating a motor torque estimation model with the detected torque errors. This allows the torque control to be improved during subsequent engine operation. For example, during a subsequent engine restart, the controller may control engine torque that is based on the updated one during the restart Motor torque estimation model is commanded. In particular, a more accurate torque command may be given during the subsequent engine restart at the time of disengagement clutch actuation.

In one example, during engine shutdown conditions, a controller may release a disconnect clutch connected between a motor and an electric machine in a vehicle driveline. The electric machine may be a CISG or other electric motor, the engine connecting the engine to the transmission and vehicle wheels of the vehicle drive shaft. Prior to releasing the disconnect clutch, the controller may command an engine torque that maintains a desired engine deceleration. The controller may then adjust one or more engine operating parameters to maintain the commanded engine torque. Thereafter, the disengagement clutch can be released. After enabling the disconnect clutch, the controller may determine torque estimation errors based on a deviation of the actual engine deceleration from the desired engine deceleration while maintaining the commanded engine torque.

In this way, torque errors may be determined during engine shutdown upon release of the clutch and during engine rotation based on an engine speed response after clutch release. By determining the torque errors in response to engine settings and applying the detected errors to provide more accurate torque control during subsequent engine operation, powertrain disturbances that occur during clutch actuation and release may be reduced and a smoother transition may be achieved.

7 FIG. 12 illustrates an example of determining torque errors during engine stop conditions in a hybrid vehicle using the in 6 In particular, the graph shows 700 Changes in engine speed when displayed 702 , Changes in engine torque when presented 704 and changes in disengagement clutch capacity when presented 706 Prior to t1, the engine may be operated at engine torque commanded based on an operator torque request (eg, based on a pedal position). Therefore, during this time, at least a portion of the requested torque may be provided by the engine. For example, the total torque request from the engine may be met. Alternatively, the entire torque request from the engine and a system battery may be met.

At t1, the engine stop conditions can be confirmed. For example, an engine idle / stop condition may be confirmed. Accordingly, a motor torque can be commanded at t1 (FIG 704 solid line) that enables the provision of substantially zero torque in a disconnect clutch that mechanically connects the rotating engine to a rotating electrical machine and then to the vehicle driveline transmission and wheels. The commanded engine torque may be determined depending on the desired engine acceleration (or in this case engine braking) and engine inertia. Between t1 and t2, the engine controller may adjust one or more engine operating parameters to obtain an estimated engine torque (plot 705 dashed line) to the desired / commanded engine torque (illustration 704 , solid line) approximate.

At t2, the estimated engine torque may settle near the target torque. Accordingly, at t2, control may be achieved by reducing clutch clutch clutch capacity (FIG 706 ), so as to release the clutch while the engine torque command (FIG 704 ) is kept constant. Thus, the controller attempts to provide zero torque via the disengagement clutch after disengaging the clutch, by determining an engine torque command that provides substantially zero torque (eg, within a zero threshold), and by providing the determined torque command (eg immediately before) commands the clutch to release.

If the engine torque command is given correctly, after the clutch is released, there should be no significant change in engine speed (ie, there is no change in speed by more than a threshold, eg, more than 10 rpm of the previous speed) and The engine may be operated in a substantially similar manner (ie, at a similar low rate) as before the clutch was released (ie, along the way) 702 ) continue to accelerate or decelerate. However, if an error has occurred in the torque estimate and, accordingly, in the commanded torque, the engine speed response deviates from the expected value after the clutch is released.

At t3 the coupling capacity can be reduced to a minimum capacity. After the clutch capacity has dropped and the clutch has been released, a motor control can be activated Monitor and estimate engine parameters over a period of time from clutch release (ie, for a period of time between t3 and t4). The parameters estimated over the defined period of time may include an average engine acceleration (Beschl_durchschn), an average engine speed (U / min_durchschn) and an average estimated engine torque (dm_durchschn). The controller may then calculate and determine a motor torque error (dm_error) as follows: dm_error = dm_durchschn - beschl_durchschn · Motor inertia

In this way, the controller may determine air and fuel supply errors necessary to provide zero torque based on a speed profile of the engine and / or the electric machine for a period of time after the clutch release.

Determining errors based on the engine speed profile includes, for example, when an actual engine speed profile is higher than an expected engine speed profile over the time period, determining an error that corresponds to overestimating engine torque. An example of torque override error or error due to excessive torque output is shown 708 (dashed and dotted line) shown. As another example, determining an error based on the engine speed profile when an actual engine speed profile is less than an expected engine speed profile over the duration of time includes determining an error corresponding to an underestimation of engine torque. An example of a torque underestimation error or an error due to a low torque output is shown 709 (dashed line) shown. In either case, the expected engine speed profile is based on the engine torque command (Graph 706 ).

The torque errors can be determined as a function of an engine speed and one or more actuator settings. For example, the error may be determined in accordance with one or more of the following settings: throttle, EGR, boost, MAF, MAP, cam timing, and valve timing at the time of torque fault identification. The detected error may then be used to update a motor torque estimation model. More particularly, the engine torque estimation model may use various parameters to estimate a friction torque, such as torque error, air pressure, engine oil temperature, average engine speed, etc. The torque error used in the torque estimation model during engine restart may be updated to reflect the torque error. detected during the immediately preceding engine shutdown.

As explained above, the approach can be determined by determining torque errors in 5 and 7 described during an engine coast stop condition are performed. That is, torque errors may be determined during engine idle-stop conditions as described above when a vehicle speed is higher than a threshold speed and while the disengaging clutch is released when the vehicle speed is above the threshold speed. Regarding 6 is an exemplary process 600 for determining torque estimation errors based on deviations in engine speed and acceleration upon release of the disengagement clutch at selected engine speed setpoints during an engine shutdown. The procedure off 6 can look like part of the routine 4 as in 414 be applied. An exemplary graph illustrating the determination of torque errors through the approach 6 is explained in 7 and 8th shown. It will be appreciated that the following approach can be used to determine torque errors upon release of a disengaging clutch, but prior to disabling fuel to the engine to shut down the engine.

at 602 The method includes determining whether an engine coast stop has been requested or expected. As above regarding 4 (at 406 ), an engine coast stop may be determined and distinguished from an engine coastdown stop based on at least one of pedal positions and a vehicle speed (with respect to a threshold) at the time the engine stop request is made. When an engine coast stop is confirmed, the routine continues to increase 604 , Otherwise, the routine continues to increase 606 to determine if an engine coast down stop was requested or expected. When an engine-non-coasting stop is confirmed, the routine continues to increase 608 , In itself, the process can 600 out 6 may be performed during an engine coast stop as well as during an engine coast down stop, however, a number of engine speed set values may be monitored and assessed at which the speed response of the engine and / or the electric machine is determined to detect torque errors , vary based on the nature of the engine stop.

at 604 and 608 a plurality of engine speed setpoints are selected at which torque estimation errors are determined. In both cases, the multiple engine speed setpoints are selected based on a motor torque error history. For example, the engine speed setpoints may be selected based on past information stored in the memory of the controller with respect to engine torque output errors. An indication of engine torque output errors at these selected engine speed setpoints may have been based on engine acceleration data and / or driveline disturbances that occurred during and after actuation and release of a disconnect clutch.

As noted above, a number of engine speed setpoints for an engine coastdown stop may vary from a motor coastdown stop. In particular, at 604 a larger number of engine speed set values are selected during the engine stop condition when the engine is coasting to rest (ie, for an engine coast stop condition), whereas at 608 a smaller number of engine speed set values is selected when the engine is stopped rapidly (eg, substantially instantaneously) (as for an engine no coast stop condition). Herein, the number of engine speed set values is selected based on a desired time to engine idle condition during engine shutdown conditions, with the number of selected engine speed setpoint values increasing with the increase of the desired time duration until engine idle (as in the case of coast down). In yet another example, the engine speed setpoints at which the errors are determined may be increased as a difference between an engine speed at which the clutch is released and the engine idle state (that is, zero speed) increases.

From 604 and 608 the routine continues to grow 610 wherein error estimation windows are determined based on the selected engine speed setpoints with a history of torque disturbances. The windows may correspond to speed windows about the selected engine speed setpoint, with error estimates to be made based on the engine (or engine) speed responses within those windows. After that can at 612 determining an engine torque command that provides substantially zero torque over a clutch release clutch clutch, the clutch mechanically coupling the engine to an electric machine and to a transmission and wheels of the vehicle drive shaft. The particular engine torque command may be commanded prior to release of the clutch, more specifically immediately prior to clutch release. In one example, the determined engine torque command may be correlated with an expected engine speed response or an engine speed profile upon release clutch release. Similarly, the particular engine torque command may be correlated with an expected engine speed response or an engine speed profile upon release of the disengagement clutch.

After that can at 614 confirmed that the disengagement clutch has been released. For example, it can be confirmed that the clutch capacity of the disengaging clutch is below a threshold or at a minimum capacity. After confirming that the disconnect clutch has been released, the procedure at 616 estimating an engine speed profile and an engine acceleration / deceleration profile at each of the selected engine speed setpoints in the particular windows. Optionally, a speed profile of an electric machine and an acceleration / deceleration profile of an electric machine may also be estimated at each of the selected engine speed setpoints in the predetermined windows. In addition to the engine speed response, actuator settings can also be estimated and determined at the selected engine speed settings in the particular windows.

at 618 For example, an expected engine speed profile and an engine acceleration / deceleration profile may be determined at each of the selected engine speed setpoints. Alternatively, an expected speed profile of an electric machine and an acceleration / deceleration profile of an electric machine may be determined for each of the selected engine speed setpoints. In one example, the expected engine speed profile may be based on the assumption of zero torque command (at 612 ). For example, the engine torque command may be selected to accelerate / decelerate the engine at an expected rate or with an expected engine speed response following release of the disconnect clutch. Similarly, the particular engine torque command may be selected to provide an expected engine speed profile or rate after the release clutch is released.

at 620 For example, the actual speed response of the engine and the actual speed response of the electric machine (at 616 estimated) with the expected values (at 618 determined). If the actual values match the expected values, then can at 622 no motor torque error can be determined. If compared with at 624 the actual value does not match the expected value, the routine determines a motor torque error based on a deviation of the actual values from the estimated values. Specifically, upon release of the disengagement clutch, the controller estimates torque errors based on deviations of an actual engine speed profile from a commanded (or expected) engine speed profile at each of a plurality of engine speed setpoints. Therefore, the routine includes determining a motor torque error based on a speed profile of the motor and / or the electric machine after the disengagement clutch is released.

It will be appreciated that torque error estimations can not be performed if the torque error estimation conditions are not met (as in FIG 4 , Step 408 and 410 illustrated). For example, the controller may not estimate torque errors when a fuel level in a vehicle fuel tank is below a threshold. As another example, if a restart is to be expected due to a change of mind of a driver, the torque error estimation may be made using the approach of 6 not be carried out. Further, when a restart request due to a sudden change of driver's senses is received during the estimation and determination of torque errors, the estimation and the determination of torque errors may be promptly interrupted and the controller may cause the engine to spin down (to accelerate an engine restart). ,

The controller may determine based on the direction of the deviation whether the estimated error occurred due to overestimation or underestimation of the engine torque. If the torque commanded prior to the release of the clutch is maintained after the clutch is released, and if the torque command was substantially equal to substantially zero torque across the clutch, then after release of the clutch, the engine speed profile should be considered with respect to the speed profile prior to clutch release remain unchanged (eg within a threshold of 10 rpm). In this way, a motor torque error may be determined in response to a change in the engine speed profile (or engine acceleration rate) after the clutch release at the specific speed reference values. The determining may further include determining an engine torque overestimation error if the actual engine speed profile in the engine speed window is higher than the expected engine speed profile and determining an engine torque underestimate error if the actual engine speed profile in the engine speed window is lower than the expected engine speed profile.

As in the examples in 8th to 9 For example, determining errors based on engine speed profile deviations at specified engine speed setpoints may be accomplished in a variety of ways. In an approach that is in 8th For example, the controller may specify an engine speed target (corresponding to a selected engine speed setpoint) and allow a controller to adjust actuator settings to maintain the engine speed at the engine speed target. The torque model error and / or the change in actuator settings (from the initial settings) required to maintain the engine speed at the target speed may then be determined. This can be repeated at each selected engine speed setpoint. In an alternative approach, in 9 For example, the controller may prescribe or command a smooth engine speed profile and may detect engine speed, engine acceleration, and engine torque (commanded and estimated values) at the selected engine speed setpoint values selected during engine deceleration. The controller may allow a controller to adjust actuator settings to enable the commanded smooth engine speed profile. Torque model errors and / or a change in actuator settings (from the initial settings) are then detected or detected at each target speed setpoint.

at 626 For example, the torque errors may be determined and stored as a function of the corresponding engine speed setpoints (where they were determined). Further, the estimated torque errors may be determined in accordance with one or more engine actuator settings, including throttle angle, valve timing, spark timing, cam timing, boost pressure, manifold airflow, etc. In one example, the controller may update the errors in a look-up table that estimates the estimated torque errors stores the motor and actuator settings.

at 628 The routine includes updating a motor torque estimation model with the estimated estimated torque errors. This allows the torque control to be improved during subsequent engine operation. For example, during a subsequent engine restart operation, the controller may actuate the disconnect clutch and adjust an engine air and fuel supply based on the detected torque errors to control engine torque, which may occur during engine cranking Clutch operation was commanded during the restart. In this way, an accurate torque command can be delivered during the subsequent engine restart, thereby reducing driveline disturbances at the time of clutch actuation. The detected torque errors may also be used to adjust engine air and fuel delivery to control engine torque commanded upon release of the clutch during a subsequent engine shutdown restart operation. In this way, an accurate torque command can be given during the subsequent engine shutdown, thereby reducing driveline disturbances at the time the clutch is released.

8th FIG. 12 illustrates a first example of determining torque errors at engine shutdown conditions in a hybrid vehicle at selected speed setpoints using the approach 6 , In particular, the graph shows 800 Changes in the speed of the electric machine when displayed 802 , Changes in engine speed at presentation 804 , Changes in engine torque at presentation 806 and changes in disengagement clutch capacity when displayed 808 , The desired (discontinuous) engine speed profile with discrete engine speed setpoints for which torque errors are progressively estimated is shown 805 shown (dashed line). It will be appreciated that the following approach can be taken to determine torque errors after releasing a disconnect clutch but before deactivating fuel to the engine to shut off the engine.

Prior to t1, the engine may be operated at a commanded engine torque based on the operator torque request (eg, based on a pedal position). Therefore, during this time, at least a portion of the requested torque may be provided by the engine. For example, the total torque request from the engine may be met. Alternatively, the entire torque request from the engine and a system battery may be met.

At t1, the engine stop conditions can be confirmed. For example, an engine idle / stop condition may be confirmed. Accordingly, a motor torque can be commanded at t1 (FIG 806 ). In one example, the requested engine torque may substantially enable zero torque in a disconnect clutch that mechanically connects the rotating engine to a rotating electrical machine and then to the vehicle driveline transmission and wheels. The commanded engine torque can be determined as a function of engine inertia, so that a specified engine speed profile (illustration 805 ) can be achieved. The specified engine speed profile (illustration 805 ) may be a discontinuous engine speed profile representing discrete target engine speeds ( 810 to 813 ), which must be reached at certain times since release of the clutch. In particular, the target engine speed setpoints may be speed setpoints at which torque errors are determined adaptively. The target engine speed setpoints may be based on calibratable adjustments or the occurrence of powertrain disturbances during disengagement of the disengagement clutch (or disengagement clutch actuation) during previous engine operation. Further, at t1, a controller may have a clutch capacity of the disconnect clutch (shown in FIG 808 ) to release the disconnect clutch. So as soon as the clutch is released, the transmission is in a neutral gear.

Therefore, the controller attempts to provide zero torque in a disengagement clutch after disengaging the disengagement clutch by determining an engine torque command that provides substantially zero torque and commanding the determined torque command prior to (eg, immediately before) disengaging the clutch. Therefore, if the engine torque command is performed correctly, there should be no significant change in engine speed or engine speed (FIG 802 ) by releasing the clutch (eg, not changing by more than a threshold amount, such as more than 10 RPM from the previous value), wherein the engine can continue the acceleration / deceleration at a low, constant rate with a speed profile based on the profile before releasing the clutch. However, if an error has occurred in the torque estimate and, accordingly, in the commanded torque, the engine speed response deviates from the expected value after the clutch is released.

At t2, the engine clutch can be released. The controller may then set a first desired engine speed setpoint 810 adjust while allowing a regulation. Accordingly, an engine torque command that sets the engine speed setpoint 810 should be given at t2. The controller may then wait until the engine speed stabilizes in the vicinity (eg, within a threshold) of the desired engine speed setpoint. Likewise, the controller may also wait for the actual engine torque command to stabilize in the vicinity (eg, within a threshold) of the requested torque. At t3, when the engine speed and the Torque has stabilized, the controller estimates the average engine acceleration (verl_durchsch), the average engine speed (rpm) and the average estimated requested engine torque (dm_durchschn) in a window that is at the target speed setpoint. In particular, the estimates may be determined in a window defined by the duration between t2 and t3 and at the first target speed setpoint 810 lies.

Between t2 and t3, the engine controller may set one or more engine operating parameters for adjusting engine torque and for approximating the actual engine speed to the target speed setpoint. The controller may then detect the actual actuator settings that are used via a control in the window between t2 and t3 to determine the engine speed at the target engine speed setpoint 810 to keep or bring him to this.

At t3, control may also include a motor torque error 820 (dm_error), which is at the engine speed setpoint 810 occurs, calculate and determine as follows: dm_error = dm_durchschn - beschl_durchschn · Motor inertia

In this way, the controller can control the torque error 820 at the selected engine speed setpoint 810 determine, including air and fuel supply errors. The controller may also determine and update the actuator settings that are used to achieve and maintain engine speed at the engine speed setpoint 810 required are.

At t3, the controller may then set a second desired engine speed setpoint 811 while continuing the control. Accordingly, an engine torque command that sets the engine speed setpoint 811 should be given at t3. The controller may then wait until the engine speed stabilizes in the vicinity (eg, within a threshold) of the desired engine speed setpoint. Likewise, the controller may also wait for the actual engine torque command to stabilize in the vicinity (eg, within a threshold) of the requested torque. At t4, when the engine speed and torque have stabilized, the controller may estimate the average engine acceleration (speed), the average engine speed (rpm), and the average estimated commanded engine torque (dm_durchschn) in a window that is at the target speed limit. Setting value is. In particular, the estimates may be determined in a window defined by the duration between t3 and t4 and at the second target speed setpoint 811 lies.

Between t3 and t4, the engine controller may adjust one or more engine operating parameters to adjust engine torque and to bring the current engine speed closer to the target speed setpoint. The controller may then detect the current actuator settings used in a control in the window between t3 and t4 to determine the engine speed at the target engine speed setpoint 811 to keep or bring them to this. At t4, control may further determine a motor torque error using the equation described above 821 (dm_error), which is at the engine speed setpoint value 811 caused, calculate and determine. In this way, the controller can control the torque error 821 at the selected engine speed setpoint 811 determine, including air and fuel supply errors. The controller may also determine and update the actuator settings that are used to achieve and maintain engine speed at the engine speed setpoint 811 required are.

Control may now begin by sequentially setting the target engine speed setpoints 812 and 813 continue and the corresponding torque error 822 and 823 in the corresponding windows t4 to t5 and t5 to t6.

Determining errors based on a deviation of an actual engine speed profile from an expected engine speed profile in an engine speed window (based on selected engine speed setpoints), for example, implies that if an actual engine speed profile is displayed in a window selected at a selected engine speed. Setpoint value is higher than an expected engine speed profile, an error corresponding to an overestimation of the engine torque is determined. Similarly, an error corresponding to an underestimation of engine torque is determined when the actual engine speed profile in a window that is at a selected engine speed setpoint is less than an expected engine speed profile.

The torque errors may be determined as a function of the corresponding engine speed setpoints and one or more engine actuator settings detected in the corresponding window. For example, the error may be determined in accordance with one or more of the following settings: throttle, EGR, boost, MAF, MAP, cam timing, and valve timing at the time of torque fault identification. Thus, air and fuel supply errors can be determined depending on the corresponding engine speed setpoints. The detected error may then be used to update a motor torque estimation model. Specifically, the engine torque estimation model may use various parameters to estimate friction torque, such as torque error, air pressure, engine oil temperature, average engine speed, etc. The torque error used in the torque estimation model during engine restart may be updated to reflect the torque error. detected during the immediately preceding engine shutdown. In this manner, the controller may control engine torque requested during a subsequent engine restart based on the determined engine torque error.

9 FIG. 12 illustrates a second example of determining torque errors at engine shutdown conditions in a hybrid vehicle at selected speed setpoints using the approach 6 , In particular, the graph shows 900 Changes in the speed of the electric machine when displayed 802 , Changes in the engine speed profile when displayed 904 (solid line), changes in engine torque when displayed 906 and changes in a clutch release capacity when displayed 908 , The desired (smooth and continuous) engine speed profile with discrete engine speed setpoints at which torque errors are progressively estimated is shown 905 shown (dashed line). It will be appreciated that the following approach can be used to determine torque errors after releasing a disconnect clutch but before deactivating fuel to the engine to shut off the engine.

Prior to t1, the engine may be operated at a commanded engine torque based on the operator torque request (eg, based on a pedal position). Therefore, during this time, at least a portion of the requested torque may be provided by the engine. For example, the total torque request from the engine may be met. Alternatively, the entire torque request from the engine and a system battery may be met.

At t1, the engine stop conditions can be confirmed. For example, an engine idle / stop condition may be confirmed. Accordingly, a motor torque can be commanded at t1 (FIG 906 ). In one example, the commanded engine torque may enable substantially zero torque via a disconnect clutch that mechanically connects the rotating engine to a rotating electrical machine and then to the vehicle drive shaft gear and wheels. The commanded engine torque can be determined as a function of engine inertia, so that a specified engine speed profile (illustration 905 ) can be achieved. The specified engine speed profile (illustration 905 ) may be a smooth and continuous engine speed profile that includes discrete target engine speed settings (FIG. 910 to 913 ), which must be reached at fixed times since release of the release clutch. In particular, the target engine speed setpoints may be speed setpoints at which torque errors are determined adaptively. The target engine speed setting values 910 to 913 may be due to calibratable adjustments or powertrain disturbances during disengagement of the disengagement clutch (or clutch apply) during previous engine operation. Also at t1, a controller can control the clutch capacity of the disconnect clutch (log 908 ) to release the clutch. So as soon as the clutch is released, the transmission is in a neutral gear.

Therefore, the controller thus attempts to enable zero torque via a disengagement clutch after disengaging the clutch by determining an engine torque command that provides substantially zero torque and commanding the determined torque command prior to (eg, immediately before) disengaging the clutch. Therefore, if the engine torque command is performed correctly, no significant change in engine speed upon release of the clutch (eg, no change by more than a threshold speed, such as more than 10 RPM from the previous value) should be initiated Acceleration / deceleration at a small and constant rate can continue with a speed profile based on the profile before releasing the clutch. However, if an error has occurred in the torque estimate and, accordingly, in the commanded torque, the engine speed profile deviates from the expected profile after the clutch is released.

At t2, the engine clutch can be released. The controller may then monitor the desired engine speed profile while enabling control and a first engine speed setpoint 910 in which torque error is determined adaptively. The controller may then wait until the engine speed approaches (eg, within the threshold) a target engine speed setpoint value 910 stabilized. At t3, if the actual engine speed profile has a speed setting, that may be the pull speed setpoint 910 The controller has estimated the average engine acceleration (verl_durchschn), the average engine speed (rpm) and the average estimated commanded engine torque (dm_durchschn) in a window that corresponds to the target speed setpoint 910 lies. In particular, the estimates may be determined in a window defined by the duration between t2 and t3 and at the first target speed setpoint 910 lies.

Between t2 and t3, the engine controller may set one or more engine operating parameters for adjusting engine torque and for approximating the actual engine speed to the target speed setpoint. The controller may then detect the actual actuator settings that are used via a control in the window between t2 and t3 to determine the engine speed at the target engine speed setpoint 910 to keep or bring him to this.

At t3, control may also include a motor torque error 920 (dm_error) caused to reflect the actual engine speed profile (plot 904 ) to the desired engine speed profile (illustration 905 ) at speed setting value 910 to calculate and calculate as follows: dm_error = dm_durchschn - beschl_durchschn · Motor inertia

In this way, the controller can control the torque error 920 at the selected engine speed setpoint 910 determine, including air and fuel supply errors. The controller may also determine and update the actuator settings that are used to achieve and maintain engine speed at the engine speed setpoint 910 required are.

Between t3 and t4, the controller may continue to monitor engine speed profile control while waiting for the engine speed to reach a second target speed setpoint 911 reached. At t4, if the actual engine speed profile has a speed setting that is the prescribed setpoint 911 the controller estimates the average engine acceleration (rpm), the average engine speed (rpm), and the average estimated commanded engine torque (dm_durchschn) in a window equal to the target speed setpoint 911 lies. In particular, the estimates may be determined in a window defined by the duration between t3 and t4 and at the second target speed setpoint 911 lies.

Between t3 and t4, the engine controller may set one or more engine operating parameters for adjusting engine torque and approximating the current engine speed to the target speed setpoint. The controller may then detect the actual actuator settings used in a control in the window between t3 and t4 to determine the engine speed at the target engine speed setpoint 911 to hold or bring on this. The controller may also provide a motor torque error 921 calculate and determine the actual engine speed profile (plot 904 ) to the desired engine speed profile (illustration 905 ) at speed setting value 911 bring to. The controller may continue to adjust the engine speed profile for a deviation in the selected target engine speed setpoints 912 and 913 to monitor sequentially and the corresponding torque errors 922 and 923 in the corresponding windows t4 to t5 and t5 to t6.

Thus, in response to idle / stop conditions, a controller may release a disconnect clutch connected between the engine and an electric machine (such as a CISG), and a controller may detect an engine speed error within an engine speed window during engine deceleration, but before Disabling fuel injection into the engine. The detected error may be estimated based on the deviation of an actual engine speed profile from an expected engine speed profile in the engine speed window after releasing the clutch. For example, the controller attempts to provide zero torque in the disengagement clutch after releasing the clutch (by commanding the zero torque immediately prior to clutch release), and thereafter while the engine is decelerating, control determines air and fuel delivery errors based upon providing zero torque are required on an engine speed profile in a window at each of the plurality of engine speed set values. As shown in the example above, the controller can control the torque errors 920 to 923 at the appropriate engine speed settings 910 to 913 determine, including air and fuel supply errors. The controller may also determine and update the actuator settings required to achieve and maintain engine speed at the corresponding engine speed setpoints.

As explained above, the approach for detecting torque errors that may occur in 6 . 8th and 9 during an engine coast stop condition and a motor no coast stop condition are performed with a number of engine speed set values selected to be larger in the engine coast stop condition than at the engine-non-coast-stop condition. Thus, if the torque errors are detected at various speed setpoints during an engine coast stop, the disconnect clutch may be released while a vehicle speed is above a threshold speed.

Thus, torque estimation errors may be determined based on an engine speed response after releasing a clutch connecting the engine to an electric machine and the remainder of the vehicle drive shaft. By determining torque errors and updating a torque estimation model, driveline torque disturbances that occur during actuation and release of a clutch can be reduced. Improving torque control improves vehicle handling. In addition, the approach can reduce drive shaft wear, increasing the useful life of the drive shaft.

As one of ordinary skill in the art appreciates, the methods described herein may represent one or more different processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, and the like. As such, the various steps or functions may be performed in the described sequence or in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily determinative of the accomplishment of the objects, features, and advantages described herein, but is provided for ease of explanation and description. Although not expressly stated, one of ordinary skill in the art will recognize that one or more of the illustrated steps or functions may be performed repeatedly, depending on the particular strategy being used.

• A. Verfahren für ein Hybridfahrzeug, umfassend: während ausgewählter Motorabschaltbedingungen, Freigeben einer Ausrückkupplung, die zwischen einem Motor und einer elektrischen Maschine in einer Fahrzeugantriebsstrang verbunden ist; und nach Freigabe der Ausrückkupplung, Schätzen von Drehmomentfehlern basierend auf Abweichungen eines tatsächlichen Motordrehzahlprofils von einem befohlenen Motordrehzahlprofil bei jedem von mehreren Motordrehzahl-Einstellwerten.
• B. Verfahren nach A, wobei die mehreren Motordrehzahl-Einstellwerte basierend auf einer Motordrehmoment-Fehlerhistorie ausgewählt werden.
• C. Verfahren nach B, wobei eine Anzahl von Motordrehzahl-Einstellwerten basierend auf einer gewünschten Dauer bis zu einem Motorruhezustand während der Motorabschaltbedingungen ausgewählt wird, wobei die Anzahl der Motordrehzahl-Einstellwerte mit Zunahme der gewünschten Dauer zum Motorruhezustand zunimmt.
• D. Verfahren nach B, wobei eine größere Anzahl von Motordrehzahl-Einstellwerten während Motorabschaltbedingungen ausgewählt wird, wenn der Motor in den Ruhezustand ausrollt, und eine kleinere Anzahl von Motordrehzahl-Einstellwerten ausgewählt wird, wenn der Motor im Wesentlichen unverzüglich angehalten wird.
• E. Verfahren nach A, ferner umfassend das Nichtschätzen der Drehmomentfehler, wenn ein Kraftstofffüllstand in einem Fahrzeugkraftstofftank unter einem Schwellenwert liegt.
• F. Verfahren nach A, ferner umfassend als Reaktion auf eine Neustartanforderung aufgrund eines Sinneswandels eines Fahrers, die während des Schätzens empfangen wird, das Unterbrechen des Schätzens von Drehmomentfehlern und Beschleunigen des Herunterdrehens des Motors in den Ruhezustand.
• G. Verfahren nach A, wobei die elektrische Maschine ein in die Kurbelwelle integrierter Starter/Generator (CISG) ist, der den Motor mit einem Getriebe und Rädern der Fahrzeugantriebswelle mechanisch verbindet.
• H. Verfahren nach Anspruch A, ferner umfassend das Ermitteln der geschätzten Drehmomentfehler in Abhängigkeit von entsprechenden Motordrehzahl-Einstellwerten und das Aktualisieren eines Motordrehmoment-Schätzungsmodells mit den geschätzten Drehmomentfehlern.
• I. Verfahren nach H, wobei die geschätzten Drehmomentfehler ferner in Abhängigkeit einer oder mehrerer Motoraktoreinstellungen, die Drosselklappenwinkel, Zündzeitpunkt, Krümmerluftströmung und Ladedruck einschließen, ermittelt werden.
• J. Verfahren nach H, ferner umfassend, während eines nachfolgenden Motorneustarts, das Betätigen der Ausrückkupplung und Einstellen der Motorluft und Kraftstoffzufuhr basierend auf den ermittelten Drehmomentfehlern, um ein Motordrehmoment zu steuern, das bei der Kupplungsbetätigung befohlen wird.
• K. Verfahren nach A, wobei das Schätzen von Drehmomentfehlern nach Freigabe der Ausrückkupplung das Schätzen von Drehmomentfehlern nach Freigabe der Ausrückkupplung und vor Deaktivierung der Kraftstoffeinspritzung in den Motor umfasst.
• L. Verfahren für einen Hybridfahrzeug-Antriebsstrang, umfassend: als Reaktion auf Leerlauf-Stopp-Bedingungen, selektives Deaktivieren eines Motors und Freigeben einer Ausrückkupplung, die zwischen dem Motor und einem CISG verbunden ist; wobei der CISG mit dem Antriebsstranggetriebe und Rädern verbunden ist; und während des Abbremsens des Motors, Beibehalten eines Motordrehmomentbefehls; und Ermitteln eines Motordrehmomentfehlers innerhalb eines Motordrehzahlfensters, wobei der Fehler basierend auf einer Abweichung eines tatsächlichen Motordrehzahlprofils von einem erwarteten Motordrehzahlprofil in dem Motordrehzahlfenster nach Freigeben der Kupplung geschätzt wird.
• M. Verfahren nach L, wobei das Motordrehzahlfenster basierend auf einem Motordrehzahl-Einstellwert ausgewählt wird, der eine Historie von Drehmomentstörungen aufweist.
• N. Verfahren nach M, wobei das Ermitteln eines Motordrehmomentfehlers innerhalb eines Motordrehzahlfensters bei jedem von mehreren Motordrehzahl-Einstellwerten ausgeführt wird, wobei die mehreren Motordrehzahl-Einstellwerte basierend auf Antriebsstrangstörungen ausgewählt werden, die während der Freigabe der Ausrückkupplung bei vorherigen Motor-Leerlauf-Stopp-Bedingungen aufgetreten sind.
• O. Verfahren nach M, wobei das Ermitteln eines Motordrehmomentfehlers Folgendes beinhaltet, Ermitteln eines Motordrehmoment-Überschätzungsfehlers, wenn das tatsächliche Motordrehzahlprofil in dem Motordrehzahlfenster höher als das erwartete Motordrehzahlprofil ist, und Ermitteln eines Motordrehmoment-Unterschätzungsfehlers, wenn das tatsächliche Motordrehzahlprofil in dem Motordrehzahlfenster niedriger als das erwartete Motordrehzahlprofil ist.
• P. Verfahren nach L, wobei das Freigeben einer Ausrückkupplung das Freigeben einer Ausrückkupplung, während eine Fahrzeuggeschwindigkeit über einer Schwellengeschwindigkeit liegt, beinhaltet.
• Q. Verfahren nach L, ferner umfassend das Ermitteln des Motordrehmomentfehlers in Abhängigkeit einer Motordrehzahl und von Aktoreinstellungen bei der Motordrehzahl und das Steuern eines Motordrehmoments, das während eines nachfolgenden Motorneustarts befohlen wird, basierend auf dem ermittelten Motordrehmomentfehler.
• R. Verfahren für ein Hybridfahrzeug, umfassend: Versuchen, über einer Ausrückkupplung nach Kupplungsfreigabe ein Nulldrehmoment bereitzustellen, wobei die Kupplung einen Motor mit einer elektrischen Maschine mechanisch verbindet; und während ein Motor mit der freigegebenen Kupplung langsamer wird, Ermitteln von Fehlern im Hinblick auf Luft und Kraftstoffzufuhr, die für die Bereitstellung des Nulldrehmoments erforderlich sind, basierend auf einem Motordrehzahlprofil in einem Fenster bei jedem von mehreren Motordrehzahl-Einstellwerten.
• S. Verfahren nach R, wobei das Versuchen, ein Nulldrehmoment in der Kupplung bereitzustellen, das Bestimmen eines Motordrehmomentbefehls, der ein Drehmoment von im Wesentlichen null bereitstellt, und das Befehlen des bestimmten Drehmomentbefehls unmittelbar vor der Kupplungsfreigabe beinhaltet.
• T. Verfahren nach R, wobei eine Anzahl von Motordrehzahl-Einstellwerten, bei denen die Fehler ermittelt werden, erhöht wird, wenn sich eine Differenz zwischen einer Motordrehzahl, bei der die Kupplung freigegeben wird, und einem Motorruhezustand erhöht und wobei die Fehler im Hinblick auf Luft und Kraftstoffzufuhr in Abhängigkeit von entsprechenden Motordrehzahl-Einstellwerten ermittelt werden.

It is generally described:

• A. A method for a hybrid vehicle, comprising: during selected engine shutdown conditions, enabling a disconnect clutch connected between an engine and an electric machine in a vehicle driveline; and after disengaging the disengagement clutch, estimating torque errors based on deviations of an actual engine speed profile from a commanded engine speed profile at each of a plurality of engine speed adjustment values.
• B. Method according to A, wherein the plurality of engine speed set values are selected based on a motor torque error history.
• C. The method of B, wherein a number of engine speed adjustment values are selected based on a desired duration to an engine idle condition during engine shutdown conditions, the number of engine speed adjustment values increasing with increasing desired engine idle condition duration.
• D. The method of B, wherein a greater number of engine speed setpoints are selected during engine shutdown conditions when the engine is coasting to rest and a smaller number of engine speed setpoints are selected when the engine is substantially immediately stopped.
• E. The method of A, further comprising not estimating the torque errors when a fuel level in a vehicle fuel tank is below a threshold.
• F. The method of A further comprising, in response to a restart request due to a driver's sense change received during the estimation, suspending the torque error estimation and accelerating the engine spin-down into idle state.
• G. A method according to A, wherein the electric machine is a crankshaft integrated starter / generator (CISG) that mechanically connects the engine to a transmission and wheels of the vehicle drive shaft.
• The method of claim A, further comprising determining the estimated torque errors in response to respective engine speed setpoints and updating a motor torque estimation model with the estimated torque errors.
• I. The method of H, wherein the estimated torque errors are further determined in response to one or more engine actuator settings including throttle angle, spark timing, manifold air flow, and boost pressure.
• J. The method of H, further comprising, during a subsequent engine restart, actuating the disconnect clutch and adjusting engine air and fueling based on the detected torque errors to control engine torque commanded in the clutch actuation.
• K. The method of A, wherein estimating torque errors after releasing the disconnect clutch comprises estimating torque errors upon release of the disconnect clutch and before deactivating fuel injection to the engine.
• A method for a hybrid vehicle powertrain, comprising: in response to idle-stop conditions, selectively deactivating an engine and releasing a disconnect clutch connected between the engine and a CISG; wherein the CISG is connected to the powertrain transmission and wheels; and during deceleration of the engine, maintaining a motor torque command; and determining an engine torque error within an engine speed window, wherein the error is estimated based on a deviation of an actual engine speed profile from an expected engine speed profile in the engine speed window after releasing the clutch.
• M. A method of L, wherein the engine speed window is selected based on an engine speed setpoint having a history of torque disturbances.
• N. Method of M, wherein determining an engine torque error within an engine speed window is performed at each of a plurality of engine speed settings, wherein the plurality of engine speed settings are selected based on powertrain disturbances that occur during release of the disengagement clutch at previous engine idle-stop conditions. Conditions have occurred.
• O. A method of M, wherein determining an engine torque error includes determining an engine torque overestimation error if the actual engine speed profile in the engine speed window is higher than the expected engine speed profile and determining an engine torque underestimate error if the actual engine speed profile in the engine speed window is lower than the expected engine speed profile is.
• P. A method of L, wherein releasing a disconnect clutch includes releasing a disconnect clutch while a vehicle speed is above a threshold speed.
• Q. The method of L, further comprising determining the engine torque error versus engine speed and actuator settings at engine speed and controlling engine torque commanded during a subsequent engine restart based on the determined engine torque error.
• R. A method for a hybrid vehicle, comprising: attempting to provide zero torque over a release clutch after clutch release, the clutch mechanically connecting a motor to an electric machine; and as an engine with the released clutch slows down, determining errors in air and fuel supply required to provide the zero torque based on an engine speed profile in a window at each of a plurality of engine speed setpoints.
• S. The method of R, wherein attempting to provide a zero torque in the clutch includes determining an engine torque command that provides substantially zero torque and commanding the determined torque command immediately prior to clutch release.
• T. A method of R, wherein a number of engine speed setting values at which the errors are determined, is increased when a difference between an engine speed at which the clutch is released, and an engine resting state increases and wherein the errors with respect to Air and fuel supply depending on corresponding engine speed set values are determined.

This completes the description. The skilled artisan can discern many changes and modifications by reading them that, however, do not depart from the spirit and scope of the description. For example, I3, I4, I5, V6, V8, V10, and V12 engines operating on natural gas, gasoline, diesel, or alternative fuel configurations could take advantage of the present disclosure.

Claims (10)

Method for a hybrid vehicle, comprising: during selected engine shutdown conditions, Enabling a disconnect clutch connected between a motor and an electric machine in a vehicle driveline; and upon release of the disconnect clutch, estimating torque errors based on deviations of an actual engine speed profile from a commanded engine speed profile at each of a plurality of engine speed setpoints. The method of claim 1, wherein the plurality of engine speed setpoints are selected based on a motor torque error history. The method of claim 2, wherein a number of engine speed set values are selected based on a desired duration up to an engine idle condition during engine shutdown conditions, wherein the number of engine speed setpoints increases with increase in desired engine idle condition duration. The method of claim 2, wherein a larger number of engine speed set values are selected during engine shutdown conditions when the engine is coasting and a smaller number of engine speed set values are selected when the engine is substantially immediately stopped. The method of claim 1, further comprising not estimating the torque errors when a fuel level in a vehicle fuel tank is below a threshold. The method of claim 1, further comprising, in response to a restart request due to a change of mind of a driver received during the estimation, suspending the estimation of torque errors and speeding down the engine to idle. The method of claim 1, wherein the electric machine is a crankshaft integrated starter / generator (CISG) that mechanically connects the engine to a transmission and wheels of the vehicle drive shaft. The method of claim 1, further comprising determining the estimated torque errors in response to respective engine speed setpoints and updating a motor torque estimation model with the estimated torque errors. The method of claim 8, wherein the estimated torque errors are further determined in response to one or more engine actuator settings including throttle angle, spark timing, manifold airflow, and boost pressure. The method of claim 8, further comprising, during a subsequent engine restart, actuating the disengagement clutch and adjusting engine air and fueling based on the detected torque errors to control engine torque commanded in the clutch actuation.

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