Powertrain control system and procedures for hybrid vehicles

Abstract

Vehicle (10) comprising the following: a powertrain (12) comprising an electric motor (18), an internal combustion engine (14) and a turbocharger (46); and a controller (48) that is programmed for this purpose, to apply a filter to an engine torque command in response to a driver request, such that for commands with a rate of increase greater than a predefined threshold, corresponding rates of increase for both engine torque and turbocharger speed are limited to respective rates less than a maximum value in order to reduce a sudden increase in emissions emitted by the engine (14), and to issue an engine torque command so that a powertrain torque meets the driver's request.

Description

[0001] The present disclosure relates to hybrid vehicles, specifically powertrain control systems.

[0002] Hybrid vehicles, as is well known, use powertrains that combine internal combustion engines with electric motors. This dual power source allows for the installation of smaller, more economical engines. However, certain inputs can still cause disturbances in the powertrain, leading to reduced fuel efficiency and increased emissions. One such input is a sudden change in the power or torque demanded by the powertrain.

[0003] The insertion of one or more turbochargers coupled to the engine provides a range of different responses to rapid changes in powertrain power demand. Generally, there is a delay between the time power is requested and the point at which the operator notices the turbocharger's assistance.

[0004] US 6,856,034 B2 discloses a method for operating a hybrid electric vehicle to reduce emissions. This involves detecting transients of torque and / or speed. When a significant transient event is detected, a motor / generator generates positive torque. US 2011 / 0276251 A1 discloses a method in which a time constant associated with the operator's torque request is determined, and a fast transient associated with the operator's torque request is detected. A limited motor torque command is provided as a function of the operator's torque request and the time constant, and motor operation is controlled during fast transients to achieve the limited motor torque command.The torque machine is operated in response to an engine torque command, the engine torque command corresponding to a difference between the operator's torque request and the limited engine torque command. DE 10 2009 010 633 A1 discloses a method and a system for reducing the specific fuel consumption of an engine under transient operating conditions. The method includes determining a first limit value of a mean effective pump pressure, determining a current value of a mean effective pump pressure, determining whether the current value of the mean effective pump pressure is greater than the first limit value of the mean effective pump pressure, and, if the current value of the mean effective pump pressure is greater than the first limit value of the mean effective pump pressure, inputting a minimum closing limit value to an electronic inlet air flow control device.

[0005] A vehicle is equipped with a powertrain comprising an electric motor, an internal combustion engine, and a turbocharger. The vehicle also features a control unit programmed to apply a filter to engine torque commands resulting from driver inputs. The filter affects commands with a rate of increase exceeding a predefined threshold, thus limiting the respective rate of increase for both engine torque and turbocharger speed to rates below a specified maximum value, thereby reducing sudden increases in emissions from the engine. The control unit also issues engine torque commands to ensure the powertrain's overall torque meets the driver's input.

[0006] A method for limiting powertrain emissions involves assigning torque commands to both a power engine and an electric motor to meet the driver's torque demand. The method further involves applying a filter to modify the power engine torque command such that, in response to a sudden increase in the driver's torque demand, the rates of increase of both the power engine torque and the turbocharger speed are limited relative to their respective maximum available rates. The method further involves increasing the engine torque command by a value equal to the value of the change in the power engine torque command, thus fulfilling the driver's sudden increase in torque demand.

[0007] A hybrid vehicle is equipped with a control unit programmed to apply a low-pass filter to a power engine torque command, so that as the driver's torque demand increases, the rate of increase in power engine torque is limited accordingly. The control unit is further programmed to apply a multiplier to a motor torque command, so that the motor's output torque is increased by an amount equal to the amount by which the power engine torque is limited.

[0008] Certain vehicles described here can reduce sudden changes in the fuel-air ratio in order to limit the ratio to a stoichiometric air-fuel ratio within a predetermined range. Fig. This is a schematic representation of a hybrid electric vehicle. The Fig.represent a series of time profiles that show the performance parameters of the powertrain in a first operating mode. Fig. is a flowchart according to a procedure of the present disclosure. The Fig. represent a series of time profiles that determine the powertrain performance parameters according to the method of Fig. show.

[0009] Embodiments of the present disclosure are described below. It should be noted, however, that the disclosed embodiments are merely examples and other embodiments may take different and alternative forms. The illustrations are not necessarily to scale; some features may be exaggerated or reduced in size to show details of certain components. Therefore, specific structural and functional details disclosed herein are not to be understood as limiting, but merely as a representative basis to provide guidance to those skilled in the art in this field for the use of the present invention in a variety of ways.As an average person skilled in the art will understand, various features illustrated and described with reference to any of the figures can be combined with features illustrated in one or more other figures to create embodiments that are not expressly illustrated or described. The combinations of features result in representative embodiments for typical applications. However, various combinations and modifications of the features, consistent with this disclosure, may be desired for particular applications or implementations.

[0010] Reference is made to Fig. , which shows a schematic representation of a hybrid electric vehicle (HEV) 10 according to an embodiment of the present disclosure. Fig.This illustrates representative relationships between the components. The actual arrangement and orientation of the components within the vehicle may vary. The vehicle 10 has a powertrain 12. The powertrain 12 has a power unit 14 that drives a transmission 16. As described in more detail below, the transmission 16 has an electric machine, such as an electric motor / generator (M / G) 18, an associated traction battery 20, a torque converter 22, and a multi-stage automatic transmission, or gearbox, 24.

[0011] The power unit 14 and the M / G 18 can both provide drive power for the HEV 10. The power unit 14 generally represents a power source, which may be an internal combustion engine, such as a gasoline, diesel, or natural gas-powered engine, or a fuel cell. The power unit 14 generates power and corresponding torque, which is provided to the M / G 18 when a disengagement clutch 26 between the power unit 14 and the M / G 18 is at least partially engaged. The M / G 18 can be implemented by any of a variety of electric machines. For example, the M / G 18 can be a permanent magnet synchronous motor. Power electronics 28 prepares the direct current (DC) supplied by the battery 20 for the requirements of the M / G 18, as described below.For example, the power electronics can provide three-phase alternating current (AC) to the M / G 18.

[0012] When the release clutch 26 is at least partially engaged, power can flow from the engine 14 to the M / G 18 or from the M / G 18 to the engine 14. For example, when the release clutch 26 is engaged, the M / G 18 can act as a generator to convert rotational energy supplied by a crankshaft 30 via the M / G shaft 32 into electrical energy, which is stored in the battery 20. The release clutch 26 can also be disengaged to disconnect the engine 14 from the rest of the drivetrain 12, so that the M / G 18 acts as the sole power source for the vehicle 10. The shaft 32 extends through the M / G 18. The M / G 18 is permanently engaged with the shaft 32, whereas the power unit 14 is only engaged with the shaft 32 when the release clutch 26 is at least partially engaged.

[0013] The M / G 18 is also connected to the torque converter 22 via shaft 30. Therefore, the torque converter 22 is also connected to the power unit 14 when the release clutch 26 is at least partially engaged. The torque converter 22 has an impeller attached to the M / G shaft 32 and a turbine attached to a transmission input shaft 343. The torque converter 22 provides a hydraulic coupling between shaft 32 and the transmission input shaft 34. A torque converter lock-up clutch 36 can also be provided, which, when engaged, frictionally or mechanically couples the impeller and the turbine of the torque converter 22, enabling efficient power transmission. The torque converter lock-up clutch 36 can be operated as a launch clutch to ensure smooth vehicle acceleration.Alternatively or in combination, a starting clutch similar to the release clutch 26 can be provided between the M / G 18 and the transmission 24 for applications that do not have a torque converter 22 or a torque converter lock-up clutch 36. In some applications, the release clutch 26 is generally referred to as the upstream clutch, and the starting clutch 36 (which may be a torque converter lock-up clutch) is generally referred to as the downstream clutch.

[0014] The transmission 24 can have (not shown) gear sets that can be selectively arranged in different gear ratios by selectively engaging friction elements such as clutches or (not shown) brakes to achieve the desired multiple single or stepped gear ratios. The friction elements are controllable via a switching routine that connects or disconnects certain elements of the gear sets to control the gear ratio between a transmission output shaft 38 and the transmission input shaft 34. The transmission 24 ultimately provides an output torque from the drive train to the output shaft 38.

[0015] As further in the representative embodiment of Fig.As shown, the output shaft 38 is connected to a differential 40. The differential 40 drives a pair of wheels 42 via corresponding axles 44, which are connected to the differential 40. The differential transmits approximately the same torque to each wheel 42 while allowing for small differences in rotational speed, for example, when the vehicle is cornering. Various types of differentials or similar devices can be used to distribute torque from the drivetrain to one or more wheels. In some applications, the torque distribution can vary, for example, depending on the specific operating mode or condition.

[0016] It is understood that the hydraulically controlled transmission 24 in combination with a torque converter 22 is merely one example of a transmission arrangement; any multi-stage transmission that receives drive torque(s) from a power unit and / or motor and then delivers torque to an output shaft in various gear ratios is suitable for use in embodiments of the present disclosure. For example, the transmission 24 can be implemented by an automated manual transmission (AMT) comprising one or more servo motors to translate / rotate shift forks along a shift rail to select a desired gear ratio. As is generally known to those skilled in the art, an AMT can be used, for example, in applications with higher torque requirements.

[0017] The engine 14 can be coupled with a turbocharger 46 to provide a higher intake air pressure, or "boost pressure," in order to force a larger volume of air into a combustion chamber of the engine 14. The increase in boost pressure generally refers to the amount by which the intake manifold pressure exceeds atmospheric pressure. Boost pressure is also representative of the additional air pressure that exceeds the pressure that would be achieved without forced intake. With respect to the increased air pressure supplied to the engine 14 by the turbocharger 46, a corresponding increase in the fuel combustion rate can be achieved. The additional increase in air pressure therefore allows the engine 14 to produce additional output power, thus increasing the engine torque.

[0018] The turbocharger 46 can be driven by the vehicle's exhaust gases, which are recirculated to drive a turbine located within the turbocharger 46. The turbine's rotation pressurizes the intake air and expels this pressurized air from the turbocharger 46 into the engine's intake manifold. Typically, there is a time delay between the point at which the engine speed is increased to generate an exhaust flow and the point at which the turbocharger 46 reaches maximum output pressure. This delay is partly due to the time required for the exhaust system and the turbocharger 46 to spool up and generate the maximum available boost pressure.Turbo lag, or the time required for the turbocharger to change its power output following a change in throttle position, can be perceived by the driver as a delay or slower throttle response during acceleration compared to a naturally aspirated engine. Inertia, friction, and supercharger load are common causes of turbo lag. While turbo lag manifests itself to varying degrees, it can be particularly problematic when rapid changes in power output are required.

[0019] Furthermore, turbo lag can vary depending on the size of the turbocharger. A smaller turbocharger can provide boost more quickly and at lower engine speeds, but may not be able to deliver as much boost at higher engine speeds when a larger volume of air is drawn into the engine. However, smaller turbochargers also carry the risk of spinning too fast at higher engine speeds when a large volume of exhaust gas flows through the turbine. Conversely, while larger turbochargers may offer greater available boost pressure, they are more susceptible to turbo lag.

[0020] The stoichiometric mixture for an internal combustion engine is the ideal fuel-air ratio that allows all the fuel in the engine's combustion chamber to burn completely without excess air. For example, in gasoline-powered engines, the stoichiometric fuel-air ratio can be approximately 1:15. Mixtures with a higher than ideal stoichiometric ratio are called rich mixtures. Those with a lower air-fuel ratio are called lean mixtures. The vehicle 10 may be equipped with at least one oxygen sensor or other feedback loop used to monitor and control the fuel-air ratios.The vehicle 10 can then automatically compensate for deviations from the ideal stoichiometric ratio by adjusting operating parameters in response to the detection of a concentration or presence of exhaust oxygen or other exhaust gas components. For example, modifying the volume of fuel supplied to the combustion chamber can be used to adjust the fuel-air ratio. According to aspects of the disclosure, the vehicle 10 modifies the operating parameters to maintain the fuel-air ratio for the engine within a predefined range around a stoichiometric fuel-air ratio.

[0021] Operating states of the powertrain 12 can be prescribed by a controller, such as a powertrain control unit (PCU). Although the PCU is shown as a single controller, it may be part of a larger control system and be influenced by various other controllers throughout the vehicle 10, such as a vehicle system controller (VSC) 48. Examples of such other controllers that may be included in the VSC 48 are a brake system control module (BSCM), a high-voltage battery controller (BECM), and other interconnected controllers responsible for various vehicle functions.The one or more other control units can be collectively referred to as a "control unit" that issues commands to various actuators in response to signals from different sensors. The response of the VSC 48 can be used to prescribe or influence a number of vehicle functions, such as starting / stopping the engine 14, operating the M / G 18 to provide wheel torque or recharge the traction battery 20, selecting or shifting gear ratios, etc. The VSC 48 can also include a microprocessor or central processing unit (CPU) that communicates with various types of computer-readable storage devices or data carriers.Computer-readable storage devices or data carriers can include volatile and non-volatile storage, for example, in read-only memory (ROM), random-access memory (RAM), and keep-alive memory (KAM). KAM is a persistent or non-volatile memory that can be used to store various operating variables while the CPU is powered off.Computer-readable storage devices or data carriers can be implemented using any of the many known storage devices, such as PROMs (Programmable Read-Only Memory), EPROMs (Electrically Erasable PROM), EEPROMs (Electrically Erasable PROM), flash memory, or any other electrical, magnetic, optical, or combined storage devices capable of storing data, some of which may be executable instructions used by the controller to control the power machine or vehicle.

[0022] The VSC 48 communicates with various sensors and actuators of the power unit / vehicle via an input / output (I / O) interface, which can be implemented as a single integrated interface providing various raw data or signal conditioning, processing and / or conversion, short-circuit protection, and similar functions. Alternatively, one or more dedicated hardware or firmware chips can be used to condition and process specific signals before they are delivered to the CPU. As is generally the case in the representative embodiment of Fig.As illustrated, the VSC 48 can transmit signals to and / or from the power unit 14, turbocharger 46, release clutch 26, M / G 18, starting clutch 36, transmission 24, and power electronics 28. Although not explicitly shown, various functions or components that can be controlled by the VSC 48 are recognizable to the average person in each of the aforementioned subsystems.Representative examples of parameters, systems and / or components that can be actuated directly or indirectly by means of control logic executed by the controller include fuel injection timing, rate and duration, throttle valve position, ignition timing (for spark-ignition engines), intake / exhaust valve setting and duration, belt drive (front-end accessory drive, FEAD) components such as alternator, air conditioning compressor, battery charging, regenerative braking, M / G operation, clutch pressure for release clutch 26, starting clutch 36 and transmission 24 and similar.Sensors that communicate inputs via the I / O interface can be used to display, for example, turbocharger boost pressure, turbocharger rotational speed, crankshaft position, engine speed (RPM), wheel speeds, vehicle speed, engine coolant temperature, intake manifold pressure, accelerator pedal position, ignition switch position, throttle valve position, air temperature, oxygen content or other exhaust gas components in the exhaust gas or their presence, intake airflow, transmission, gear ratio or mode, transmission oil temperature, transmission turbine speed, torque converter lock-up clutch status 36, deceleration or shift mode.

[0023] The VSC 48 also features a torque control logic function. The VSC 48 can interpret driver requests based on various vehicle inputs. These inputs can include, for example, gear selection (PRNDL), accelerator pedal inputs, battery temperature, voltage, current, and battery state of charge (SOC). The VSC 48, in turn, can provide a gear selection command signal to the transmission based on an engine speed request derived from at least some of the inputs mentioned above.

[0024] A driver of the vehicle 10 can provide an input at the accelerator pedal 50, generating a torque or power request, or a driving command to propel the vehicle 10. Generally, pressing and releasing the pedal 50 generates an accelerator pedal input signal, which the VSC 48 can interpret as a request for higher or lower power. Based on at least one input from the pedal, the controller 48 can assign torque commands between the power unit 14 and / or the M / G 18 to fulfill the torque requested by the driver. The controller 48 can also control the timing of gear changes in the transmission 24, as well as the engagement or disengagement of the release clutch 26 and the torque converter lock-up clutch 36. Like the release clutch 26, the torque converter lock-up clutch 36 can be adjusted over a range between the engaged and disengaged positions.This generates variable slip in the torque converter 22 in addition to the variable slip generated by the hydrodynamic coupling between the impeller and the turbine. Alternatively, the torque converter lock-up clutch 36 can be operated in a locked or open state without using a modulated operating mode, depending on the specific application.

[0025] To propel the vehicle with the motor 14, the release clutch 26 is at least partially engaged to transmit at least a portion of the motor's torque via the release clutch 26 to the M / G 18 and then from the M / G 18 through the torque converter 22 and the transmission 24. The M / G 18 can assist the motor 14 by providing additional torque to rotate the shaft 32. This operating mode can be referred to as "hybrid mode" or "electrically assisted mode." As mentioned above, the VSC 48 can also be operated to issue commands to allocate torque output to both the motor 14 and the M / G 18 such that the combination of both torque outputs satisfies an input from the driver via the accelerator pedal 50.

[0026] To power the vehicle 10 with the M / G 18 as the sole power source, the energy flow remains the same, except that the release clutch 26 disconnects the motor 14 from the rest of the drivetrain 12. During this time, combustion in the motor 14 can be deactivated or otherwise switched off, for example, to save fuel. The traction battery 20 transfers stored electrical energy via cable 52 to the power electronics 28, which may include an inverter. The power electronics 28 converts high-voltage direct current from the battery 20 into alternating current for the M / G 18. The VSC 48 can also issue commands to the power electronics 28, enabling the M / G 18 to provide positive or negative torque to the shaft 32. This operating mode can be referred to as the "purely electric" operating mode.

[0027] In any operating mode, the M / G 18 can function as a motor and provide drive power for the powertrain 12. In particular, under conditions requiring a high rate of increase in powertrain torque, such as when starting the vehicle from a standstill, the motor torque command can be increased to provide adequate torque for the entire powertrain. The M / G 18 can have an initial high output torque to provide additional powertrain torque until the motor torque reaches its maximum available torque. Once the motor torque reaches its maximum available torque, the motor's torque output can be reduced or deactivated.

[0028] Alternatively, the M / G 18 can operate as a generator to convert kinetic energy from the drivetrain 12 into electrical energy, which is to be stored in the battery 20. For example, the M / G 18 can function as a generator while the engine 14 provides the sole driving power for the vehicle 10. Furthermore, the M / G 18 can also function as a generator during regenerative braking, when rotational energy from the rotating wheels 42 is transferred back via the transmission 24 and converted into electrical energy for storage in the battery 20.

[0029] It is understandable that the in Fig.The schematic representation shown is merely exemplary and not to be understood as limiting. Other configurations are considered that use the selective engagement of both a power unit and a motor to transmit power via a transmission. For example, the M / G 18 can be offset from the crankshaft 30, an additional motor can be provided to start the power unit 14, and / or the M / G 18 can be positioned between the torque converter 22 and the transmission 24. Other configurations are considered without deviating from the scope of protection of this disclosure.

[0030] Sudden increases in the driver's torque demand generally cause rapid responses to the engine's throttle position in an attempt to increase engine torque as quickly as possible and achieve maximum power to meet the driver's demand. A high rate of change in engine torque can, in turn, cause a sudden change in the fuel-air ratio. Richer fuel mixtures may result in some unburned fuel being expelled from the engine, leading to spikes in vehicle emissions as a result of hard acceleration.

[0031] Fig. presents a series of corresponding time profiles for various operating parameters of the powertrain. Fig. Each corresponds to a specific time period and shows different vehicle operating parameters that occur as a result of driver requirements. Fig.This is a curve representing driver input over time. Curve 110 depicts a driver input and shows a sudden increase in driver input, represented by a step in the input. The input step increases at time T0.

[0032] Fig.This is a corresponding time course of various torque parameters of the powertrain. Curve 112 represents a power engine torque command that increases from time T0 in response to the increased driver demand. It should be noted that during conventional operation, the power engine torque command 112 also simulates a step-like increase, which replicates the sudden change in driver demand. Curve 114 represents the actual torque output of the power engine in response to the power engine torque command. Since the power engine torque generally cannot be increased instantly, curve 114 for the actual torque output of the power engine rises along an initial rate of increase indicated by flank 116. In vehicle systems such as the one described by Fig.The torque output of the power unit is limited only by the power unit's capacity limits. Curve 118 represents the engine's output torque. Generally, the engine torque can be increased considerably faster than the power unit torque. In this way, the engine torque 118 can rise rapidly in response to a driver request to provide additional drivetrain torque for the period during which the power unit torque is increasing. Afterward, the engine torque is reduced in proportion to the increase in the actual output torque 114 of the power unit. At point 120, the engine can be completely deactivated and become a load on the power unit, generating negative torque, for example, in generator mode.

[0033] Fig.This is a time course of a fuel-air ratio in a combustion chamber of the engine. Curve 122 shows how the ratio is affected by sudden increases in driver demand. The region 124 represents a stoichiometric range, which is generally a stable state. At time T0, and in response to a sudden change in driver demand, there is a sudden increase 126 in the fuel-air ratio, causing a rich combustion condition due to the attempt to suddenly increase the powertrain torque. Once the rate of increase of the engine torque is reduced, the fuel-air ratio returns to a stable stoichiometric mixture at 128.

[0034] Fig.This is a time-dependent curve of the turbocharger boost pressure, in which curve 130 shows the boost pressure's response to a sudden increase in the driver's torque demand. At T0, the boost pressure begins to rise as the turbocharger speed increases, until a maximum available boost pressure is reached at point 132. The period between T0 and point 132 can be perceived by a driver as turbo lag, as discussed above.

[0035] Fig. This is a time course of emissions from the vehicle's engine. Curve 134 represents the emission response in relation to the sudden increase in the fuel-air ratio as shown above. Fig.described. Also related to the attempt to rapidly increase the engine torque, there is a sudden increase in emissions (136). Corresponding to the changes in the fuel-air mixture, the emissions return to a generally stable state (138) once the engine reaches full torque and is operating at a generally stable power output.

[0036] An algorithm is provided to reduce emissions by preventing a sudden increase in the fuel-air mixture ratio, which is usually a reaction to a sudden increase in the driver's torque demand. Fig.Method 200 represents an embodiment of the VSC torque control logic. The torque control logic can use the driver's torque request 202 as inputs, as well as the operating parameters 204 of a turbocharger. Step 206 can include detecting the rotational speed of the turbocharger. Similarly, step 208 can include detecting the turbocharger boost pressure 208.

[0037] Initially, the procedure 200 may involve, in steps 210 and 212, assigning commands for a desired torque between the power unit and the engine to fulfill a driver request. The initial assignment may determine hybrid operation based on maximum available torque and additional engine torque to meet the driver's torque request 202. As discussed above, when rapid increases in torque occur, applying the maximum available power unit torque may cause a sudden increase in the fuel-air ratio and / or emissions from the power unit. Accordingly, the procedure 200 involves applying a variable low-pass filter to the power unit torque delivery command.

[0038] Step 214 involves calculating a variable time constant for the low-pass filter. The time constant can vary based on at least one of the turbocharger speed, detected in step 206, and the turbocharger boost pressure, detected in step 208. In this way, the effect of the filter is constantly changed as the turbocharger spools up to its full operating capacity. The time constant can also be functionally related to at least one of the turbocharger parameters mentioned above. For example, the controller can have a stored lookup table that specifies predefined time constant values ​​or perform mathematical calculations to derive the filter's time constant in real time.

[0039] In step 216, the low-pass filter is applied to the command for a desired engine torque calculated in step 210. Using the time constant determined in step 214, the filter operates to limit the rate of increase of the engine torque commands despite sudden increases in driver demand. Due to the variable nature of the filter's time constant, the magnitude of the command signal that is filtered out changes as the turbocharger builds up its maximum power. Applying the filter to the desired engine torque in step 216 results in a modified engine torque, which may be a reduced torque that ultimately limits the rate of increase of the actual engine torque output. The filter effectively reduces an engine torque command with a rate of increase greater than a predefined threshold.In step 218, a modified torque command is issued to the power machine, based on the filtered initial desired power machine torque. Although a low-pass filter is described here, it should be clear that alternative filter topologies may be suitable for modifying power machine torque commands to reduce emissions, as well as for other purposes. Other such filter types can also be provided with variable time constants, as described above.

[0040] To ensure the vehicle's powertrain fully meets the driver's torque demand, it may be necessary to increase the engine torque beyond the initially desired value to adequately complement the powertrain's output. Step 220 calculates a modified engine torque, partially based on deficits in the engine torque resulting from the filtered torque command. The modified engine torque can be increased by an amount equal to the amount by which the engine torque was limited in filtering step 216. Alternatively, a multiplier can be applied to the engine torque command signal to achieve a similar effect.

[0041] The control algorithms described here improve the vehicle's operating performance in several ways. Reduced emissions from the engine during rapid changes in torque delivery can be achieved. Furthermore, the effects of turbo lag can be at least partially mitigated by measuring the increase in engine torque. Fig. presents a series of corresponding time profiles for various operating parameters of the powertrain. Fig. They correspond in time and show similar vehicle operating parameters as Fig. , which occur as a result of driver requirements. Fig. This is a curve representing the driver demand over time. Curve 310 depicts a driver input and shows a sudden increase in driver demand, represented by a step in the input. The input step increases at time T0.

[0042] Fig.This is a corresponding time course of various torque parameters of the powertrain. Curve 312 represents a power engine torque command that increases from time T0 in response to the increased driver demand. Compared to conventional operation, the rate of change of the power engine torque command, represented by curve 312, is limited below the full available power engine torque, despite a sudden increase in driver demand. Curve 314 represents the actual torque output of the power engine in response to the power engine torque command 312. Relative to the limited rate of change in the power engine torque command 312, curve 314 for the actual torque output of the power engine rises along an initial rate of change indicated by slope 316.It should be noted that the actual power unit output can be kept significantly closer to the measured power unit torque command compared to a conventional system. Curve 318 represents an output torque of the engine. As in other cases, the engine torque 318 is increased very rapidly in response to a driver request to provide additional drivetrain torque. However, a higher engine output torque is maintained for a longer period so that the power unit can build torque more slowly. At point 320, the engine is deactivated and can begin to generate negative torque on the drivetrain.

[0043] Fig.This is a time course of a fuel-air ratio in a combustion chamber of the engine. Curve 322 shows how the ratio can vary in response to sudden increases in driver demand. Region 324 represents a stoichiometric range, which is generally a stable state. At time T0, and in response to a sudden change in driver demand, there may be some degree of fluctuation in the fuel-air ratio at 326. However, systems according to the present disclosure can be configured to maintain the fuel-air ratio within a predetermined range 328 around the stoichiometric fuel-air ratio. In this way, the fuel-air ratio for combustion is kept closer to a stable state, regardless of a sudden change in driver demand.

[0044] Fig.This is a time course of the turbocharger boost pressure, in which curve 330 shows the boost pressure response to a sudden increase in the driver's torque demand. At T0, the boost pressure begins to rise as the turbocharger speed increases, until a maximum available boost pressure is reached at point 332. Although not shown in the diagram, the rate of increase in turbocharger speed can generally be constant, as a consequence of a limited increase in engine torque. The turbocharger speed may increase linearly during certain parts of the spool-up and therefore be limited below an available maximum value. Nevertheless, after a similar duration compared to other systems, the turbocharger can still reach maximum turbocharger power.Since the level of engine support can be based on the condition of the turbocharger, the effect of turbo lag is reduced in the driver's perception.

[0045] Fig. This is a time course of emissions from the vehicle's engine. Curve 334 represents emissions in response to a sudden increase in driver demand. Because a sudden increase in the fuel-air ratio during combustion is avoided, emissions can be kept in a more stable state. Although some fluctuation may occur as a result of aggressive acceleration of the vehicle, as described in 336, sudden increases in emissions from the engine are largely limited, as discussed here.

[0046] This disclosure provides representative control strategies and / or logic that can be implemented using one or more processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, and similar approaches. Therefore, various steps or functions illustrated here can be executed in the sequence shown, in parallel, or optionally omitted. Although not always explicitly stated, it is apparent to the average person skilled in this field that one or more of the illustrated steps or functions can be executed repeatedly, depending on the processing strategy employed.Similarly, the order in which things are processed is not strictly necessary to achieve the features and benefits described here, but is merely provided for better illustration and description.

[0047] The control logic can be primarily implemented as software, executed by a microprocessor-based vehicle, engine, and / or powertrain control unit. Of course, the control logic can also be implemented as software, hardware, or a combination of both in one or more control units, depending on the specific application. If implemented as software, the control logic can be provided in one or more computer-readable storage devices or as a data carrier containing stored data that represents code or instructions executed by a computer to control the vehicle or its subsystems.The computer-readable storage devices can include one or more of a variety of known physical devices that use electrical, magnetic, and / or optical storage to store executable instructions and associated calibration information, operating variables, and the like. Alternatively, the processes, procedures, or algorithms can be integrated, in whole or in part, into suitable hardware components, such as application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), state machines, controllers, or other hardware components or devices, or a combination of hardware, software, and firmware components.

[0048] Although exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms covered by the claims. The terms used in this specification are merely descriptive and do not imply any limitation. It is understood that various modifications can be made without departing from the spirit and scope of the disclosure. As described above, the features of different embodiments can be combined to form further embodiments of the invention, which are not expressly described or illustrated here.Even if various embodiments could have been described as advantageous or preferred over other embodiments or implementations according to the prior art with respect to one or more desired property(ies), those skilled in the art recognize that one or more features or properties may be included to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes include, but are not limited to, cost, strength, durability, life-cycle costs, marketability, appearance, packaging, size, usability, weight, manufacturability, ease of assembly, etc.Thus, embodiments that are described as less desirable than other embodiments or implementations according to the prior art with regard to one or more properties do not fall outside the scope of protection of the disclosure and may be desirable for certain applications. LEGEND Fig. 3 Fig. 202 Received torque request from the driver 210 Desired engine torque (T') KRAFTMASCHINE ) calculate 212 Desired engine torque (T') MOTOR ) calculate 206 Measure turbocharger speed 214 Calculate the time constant of the low-pass filter 208 Measure turbocharger boost pressure 216 Modified engine torque (T) KRAFTMASCHINE )calculate by filtering the desired engine torque (T') KRAFTMASCHINE ) 218 Output power machine torque request signal 220 Calculate modified engine torque (T MOTOR ) = (T' MOTOR ) + (T' KRAFTMASCHINE - T KRAFTMASCHINE ) 222 Output motor torque request signal

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