GB2493745A - A method for operating a hybrid powertrain - Google Patents

Abstract

A method for operating a hy­brid powertrain 100 comprising an internal combustion engine 110 and a motor-generator electric unit 500 is provided. The operating method comprises the steps of: determining an overall value Ptot of power to be delivered by the hybrid powertrain 100; using this overall value Ptot and a predetermined polynomial function having as variables an unknown value x of power to be delivered by the inter­nal combustion engine 110 and an unknown value y of power to be delivered by the motor-generator electric unit 500, to determine a contributing value Pice, of power to be requested to the internal com­bustion engine and a contributing value Pmgu of power to be requested to the motor-generator electric unit 500; and operating the inter­nal combustion engine 110 and the motor-generator electric unit 500 to deliver the respective contributing value of power Pice, Pte; the predetermined polynomial function comprising a term whose value depends on a value Pnoise of an acoustic power of a combustion noise generated by the internal combustion engine 110.

Description

S METECE) FOR OPERM"ING A HYBBW PCMERTBADI

TEQHAIL FUZD

The present invention relates to a method for operating a hybrid po-wertrain of a motor vehicle.

BAQ

It is known that any motor vehicle is equipped with a powertrain, namely with a group of components and/or devices that are provided for generating mechanical power and for delivering it to the final drive of the motor vehicle, such as for example the drive wheels of a car.

A hybrid powertrain particularly comprises an internal combustion en-gine (ICE), such as for example a compression-ignition engine (Diesel engine) or a spark-ignition engine (gasoline or gas engine) r and a motor-generator electric unit (MGU). The MGU can operate as an elec-tric motor for assisting or replacing the ICE in propelling the motor vehicle, and can also operate as an electric generator, especially when the motor vehicle is breaking, for charging an electrical energy storage device (battery) connected thereto. The battery is then pro-vided for powering the MGU, when it operates as electric motor, so that the only source of energy necessary for operating the hybrid po-wertrain is the ICE fuel.

The ICE and the MOO are controlled by an electronic control unit (ECU) according to a Hybrid Operating Strategy (HOS). During the pro-pulsion of the motor vehicle, the HOS provides for determining an overall value of mechanical power to be delivered to the final drive of the motor vehicle, for splitting this overall value in a first contributing value of mechanical power to be requested to the ICE and a second contributing value of mechanical power to be requested to the MOO, and then for operating the ICE and the MOO to deliver to the final drive of the motor vehicle the respective contributing value of mechanical power.

The splitting of the power overall value is optimized by determining, among the infinite couples of first and second contributing values whose addition is equal to the overall value, the couple that minim- ize the result of a predetermined polynomial function, usually re-ferred as target function, whose variables include an unknown value of the ICE power contribution and an unknown value of the MOO power contribution.

The target function comprises several terms, each of which depends on a power loss that is correlated to a specific aspect of the operation of the hybrid powertrain. The power loss is intended as a quantity of power that has been supplied to the hybrid powertrain through the ICE fuel, but that cannot be delivered to the final drive of the motor vehicle, for example because it has been dissipated or howsoever used in that specific aspect of the hybrid powertrain operation.

More particularly, a conventional target function generally comprises a first term, whose value depends on a power quantity lost by the ICE (due to its thermo-mechanical efficiency and to the friction loss in the kinematical chain connecting the ICE to the final drive of the motor vehicle), a second term, whose value depends on a power quanti-ty that is lost by the ICE due a possible slowing down of the ICE warm-up phase caused by the operation of the MGU and vice versa, a third term, whose value depends on a power quantity that is lost by the MGU (due to its electromechanical efficiency and the friction loss in the kinematical chain connecting the MW to the final drive of the motor vehicle) and by the electrical battery connected thereto (due to it chemical efficiency), and finally a fourth term, whose value depends on a fictitious loss of power quantity that accounts for the state of charge of the electric battery.

A drawback of the conventional HOS is related to the Noise, Vibration and Harshness (NVH) comfort level of the motor vehicle. The NVH com-fort level is a parameter that evaluates the overall amount of noise and vibration that is perceived by the occupants of the motor ye-hide. The NVH comfort level is affected by several factors, the most important of which are the noise generated by the combustion processes within the ICE, the noise generated by the aerodynamic of the motor vehicle, and the noise generated by the motor vehicle tires that roll on the road. However, as long as the speed of the motor ve-hicle is low, the aerodynamic noise and the tire-rolling noise are a]nost irrelevant, so that the ICE combustion noise becomes the most worsening factor of the NVH comfort level. Rs a consequence, in order to improve the NVH comfort level in this conditions, it could some-times be better to reduce the combustion noise by reducing the ICE power contributicn and by correspondently increasing the NGU power contribution.

However, the conventional BbS is completely unable to perform this kind of optimization. On the contrary, when the hybrid powertrain is requested to accelerate the motor vehicle starting from a low initial speed, the conventional HOS generally tends to reduce the P4CU power contribution and to increase the ICE power contribution, thereby fur-ther increasing the combustion noise.

An object of an embodiment of the present invention is therefore to solve this drawback. Another object is to reach this goal with a sim-ple, rational and rather inexpensive solution.

DISGIOSURE

These and/or other objects are attained by the characteristics of the embodiments of the invention as reported in independent claims. The dependent claims recite preferred and/or especially advantageous fea-tures of the embodiments of the invention.

In particular, an embodiment of the invention provides a method for operating a hybrid powertrain comprising an internal ccirbustion en- gine (ICE) and a motor-generator electric unit (t4GU), wherein the op-erating method comprising the steps of: -determining an overall value of power to be delivered by the hybrid powertrain, -using this overall value and a predetermined polynomial func-tion (target function) having as variables an unknown value of power to be delivered by the ICE and an unknown value of power to be delivered by the MGU, to determine a contributing value of power to be requested to the ICE and a contributing value of power to be requested to the NGU, and -operating the ICE and the MCD to deliver the respective contri-buting value of power, and wherein the predetermined polynomial function comprises a term whose value depends on a value of an acoustic power of a combustion noise generated by the ICE.

Thanks to this term of the target function, while determining the ICE power contribution and the MGU power contribution, the hybrid operat-ing strategy takes into account also the combustion noise of the ICE, so that it can advantageously increase the MGU power contribution ra-ther than the ICE power contribution whenever the combustion noise could become too annoying for the vehicle occupants, for example when the hybrid powertrain is requested to accelerate the motor vehicle starting from a low vehicle speed.

According to an aspect of the invention, the value of the above named term particularly depends on the logarithm of the acoustic power val-ue of the combustion noise.

The use of this logarithmic approach has the advantage of being more consistent with the way the vehicle occupants perceive the noise dis-comfort.

According to another aspect of the invention, the acoustic power val-ue of the corthustion noise is determined on the basis of the unknown value of power to be delivered by the ICE.

In this way, the value of the target function term here concerned is correctly correlated to the unknown ICE power value, thereby further bptimizing the determination of the ICE power contribution and the MGU power contribution.

In order to make the acoustic power value still more reliable, it can be determined on the basis of a value of an engine torque and a value of an engine speed, wherein the engine torque value depends on the unknown value of power to be delivered by the internal combustion en-gine.

For example, the value of the engine torque and the value of the en-gine speed may be used as inputs of an empirically calibrated map that returns as output a correlated value of the acoustic power.

This aspect of the invention has the advantage that the use of the empirically calibrated map, which can be stored in a memory system associated with the ECU, reduces the computational effort needed to carry out the HOS.

According to another aspect of the invention, the predetermined poly-nomial equation (target function) further comprises an additional term whose value is zero, if a switchable coolant pump coupled with the ICE is switched-off, and it depends on a value of a power lost by the hybrid powertrain for operating the switchable coolant pump, if the switchable coolant pump is switched-on.

A switchable coolant pump is usually embodied as a conventional me-chanical pump having the peculiarity of being connected with the ICE through a mechanical transmission comprising a clutch. The clutch can be moved between an engaged position, in which the pump is driven by the ICE (the pump is switched-on), and a disengaged position, in which the pump is disconnected by the ICE and stops (the pump is switched-off) . The clutch is moved with the aid of an electric actua- tar, which is connected with the electric battery of the hybrid po-wertrairi. As long as the electric actuator is powered by the electric battery, the clutch is kept in the disengaged position; a spring be-ing provided for moving the clutch in the engaged position, when the electric actuator is powered-off. The powering of the electric actua- tor is usually controlled by the ECU on the basis of one or more op-erating parameter of the ICE, typically on the basis of the engine torque and the engine speed.

In view of the above, it follows that the overall power lost by a hy-brid powertrain equipped with a switchable coolant pump depends also on whether the switchable coolant pump is actually switched-on or switched-off.

The last mentioned aspect of the invention has therefore the advan-tage of allowing the I-lOS to take into account also the power lost by the switchable coolant pump, thereby determining an ICE power contri-bution and a MGU power contribution that are really able to minimize the overall power losses of a hybrid power train equipped with a switchable coolant pump.

According to an aspect of the invention, the switchable coolant pump is determined to be switched-on or switched-off depending on the un-known value of power to be delivered by the ICE.

In this way, the value of the above named additional term of the tar-get function is correctly correlated to the unknown ICE power value, thereby further optimizing the determination of the ICE power contri-bution and the MOO power contribution.

In order to determine more reliably whether the switchable coolant pump is switched-on or switched-off, it can be done on the basis of a value of an engine torque and a value of an engine speed, wherein the engine torque value depends on the unknown value of power to be deli-vered by the internal corrustion engine.

For example, the value of engine torque and the value of engine speed can be used as inputs of an empirically calibrated map that returns as output whether the switchable coolant pump is correspondently switched-on or switched-off.

This aspect has the advantage that the use of the empirically cali-brated map, which can be stored in a memory system associated with the ECU, reduces the computational effort needed to carry out the HOS.

According to another aspect of the invention, the value of the power lost by the hybrid powertrain for operating the switchable coolant pump depends on a value of one or more (possibly all) of the follow- ing parameters: a power spent by the ICE to drive the switchable coo-lant pump, a power spent to declutch the switchable coolant pump from the ICE, and a variation of power lost by frictions in the ICE due to a variation of an engine temperature caused by the operation of the switchable coolant pump.

The methods according to the invention can be carried cut with the help of a computer program comprising a program-code for carrying out all the steps of the method described above, and in the form of a computer program product comprising the computer program.

The method can be also embodied as an electromaqnetic sional, said signal being modulated to carry a sequence of data bits which represent a computer program to carry out all steps of the method.

Mother embodiment of the present invention provides an apparatus for operating a hybrid powertrain comprising an ICE and a MCU, wherein the apparatus comprises: -means for determining an overall value of power to be delivered by the hybrid powertrain, -means for using this overall value and a predetermined poly- nomial equation (target function) having as variables an un-1-0 known value of power to be delivered by the ICE and an unknown value of power to be delivered by the MGU, to calculate a con- tributing value of power to be requested to the ICE and contri-buting value of power to be requested to the MGU, and -means for operating the ICE and the NGU to deliver the respec-tive contributing value of power, and wherein the predetermined polynomial equation comprises a term whose value depends on a value of an acoustic power of a combustion noise generated by the ICE.

This embodiment of the invention has the same advantage of the method disclosed above, particularly that of allowing the hybrid operating strategy to take into account also the combustion noises of the ICE, so that it can advantageously increase the MGU power contribution ra-ther than the ICE power contribution whenever the combustion noise could become too annoying for the vehicle occupants.

Still another embodiment of the invention provides a hybrid power-train comprising an ICE, a MGU, and an electronic control unit (ECU) configured to: -determine an overall value of power to be delivered by the hy-brid powertrain, -use this overall value and a predetermined polynomial function (target function) having as variables an unknown value of power to be delivered by the ICE and an unlmown value of power to be delivered by the MGI), to determine a contributing value of pow-er to be requested to the ICE and a contributing value of power to be requested to the MGU, and -operate the ICE and the MGU to deliver the respective contri-buting value of power, wherein the predetermined polynomial function comprises a term whose value depends on a value of an acoustic power of a combustion noise generated by the ICE.

Also this embodiment of the invention has the advantage of the method disclosed above, particularly that of allowing the hybrid operating strategy to take into account also the combustion noises of the ICE, so that it can advantageously increase the MGU power contribution ra-ther than the ICE power contribution whenever the combustion noise could become too annoying for the vehicle occupants.

BRIEF DEScRIPTICt1 OF THE DRAWINGS The present invention will now be described, by way of example, with reference to the accompanying drawings.

Figure 1 schematically represents a hybrid powertrain of a motor ve-hicle.

Figure 2 is a flowchart of a method for operating the hybrid power-train of figure 1.

Figure 3 shows in more details an internal combustion engine belong-S ing to the hybrid powertrain of figure 1.

Figure 4 is a section A-A of the internal combustion engine of figure 3.

Dfl DESCRIPTICV Some embodiments may include a motor vehicle's mild hybrid powertrain 100, as shown in Figures 1, that comprises an internal combustion en-gine (ICE) 110, in this example a diesel engine, a motor-generator electric unit (MGU) 500, an electric energy storage device (battery) 600 electrically connected to the MGU 500, and an electronic control unit (ECU) 450.

As shown in figure 3 and 4, the ICE 110 has an engine block 120 de- fining at least one cylinder 125 having a piston 140 coupled to ro-tate a crankshaft 145, which may be connected with a final drive of the motor vehicle, for example to drive wheels. A cylinder head 130 cooperates with the piston 140 to define a combustion chamber 150. A fuel and air mixture (not shown) is disposed in the combustion cham- ber 150 and ignited, resulting in hot expanding exhaust gasses caus-ing reciprocal movement of the piston 140. The fuel is provided by at least one fuel injector 160 and the air through at least one intake port 210. The fuel is provided at high pressure to the fuel injecto: from a fuel rail 170 in fluid corrinunication with a high pressure fuel pump 180 that increases the pressure of the fuel received from a fuel source 190. Each of the cylinders 125 has at least two valves 215, actuated by a camshaft 135 rotating in tilne with the crankshaft 145. The valves 215 selectively allow air into the combustion chamber from the port 210 and alternately allow exhaust gases to exit through at least one exhaust port 220. In some examples, a cam phaser 155 may selectively vary the timing between the camshaft 135 and the crankshaft 145.

The air may be distributed to the air intake port(s) 210 through an intake manifold 200. An air intake pipe 205 may provide air from the ambient environment to the intake manifold 200. In other embodiments, a throttle body 330 may be provided to regulate the flow of air into the manifold 200. In still other embodiments, a forced air system such as a turbocharger 230, having a compressor 240 rotationally coupled to a turbine 250, may be provided. Rotation of the compressor 240 increases the pressure and temperature of the air in the intake pipe 205 and manifold 200. An intercooler 260 disposed in the intake pipe 205 may reduce the temperature of the air. The turbine 250 ro-tates by receiving exhaust gases from an exhaust manifold 225 that directs exhaust gases from the exhaust ports 220 and through a series of vanes prior to expansion through the turbine 250. This example shows a variable geometry turbine (VGT) with a VGT actuator 290 ar-ranged to move the vanes to alter the flow of the exhaust gases through the turbine 250. In other embodiments, the turbocharger 230 may be fixed geometry and/or include a waste gate.

The exhaust gases exit the turbine 250 and are directed into an cx-haust system 270. The exhaust system 270 may include an exhaust pipe 275 having one or more exhaust aftertreatment devices 280. The after- treatment devices may be any device configured to change the corrposi-tion of the exhaust gases. Some examples of aftertreatment devices 280 include, but are not limited to, catalytic converters (two and three way), oxidation catalysts, lean NOx traps, hydrocarbon adsor-bers, selective catalytic reduction (5CR) systems, and particulate filters. Other embodiments may include an exhaust gas recirculation (EGR) system 300 coupled between the exhaust manifold 225 and the in-take manifold 200. The EGR system 300 may include an EGR cooler 310 to reduce the temperature of the exhaust gases in the EGR system 300.

An EGR valve 320 regulates a flow of exhaust gases in the EGR system 300.

As shown in figure 1, the ICE 110 is further equipped with an engine coolant circuit 470 for cooling at least the engine block 120 and the cylinder head 130. In this example, the engine coolant circuit 470 comprises a switchable coolant pump 475 that delivers a coolant, typ-ically a mixture of water and antifreeze, to a plurality of cooling channels not shown) cast in the engine block 120 and/or in the cy-linder head 130, and a radiator 480 for cooling down the coolant, once it has passed through the cooling channels.

The switchable coolant pump 475 may be embodied as a conventional me-chanical pump that is connected with the crankshaft 145 of the ICE by means of a clutch 485. The clutch 485 comprises a driving mem-ber 486, which may be constantly connected with the crankshaft 145 through a transmission belt 487, and a driven member 488, which may be constantly connected with the pump 475 and which may be moved to and from the driving member 486, between an engaged position, in which it is connected to the driving member 486 so that the pump 475 is driven by the crankshaft 145 (the pump is switched-on), and a dis-engaged position, in which it is disconnected from the driving member 486 so that the pump 475 stops (the pump is switched-off). A spring 489 is provided for constantly thrusting the driven member 488 in the engaged position. The driven member 488 may be moved in the disen-gaged position by an electric actuator 490, in this example a linear electric actuator, which is connected with and powered by the elec-tric battery 600. More particularly, as long as the electric actuator 490 is powered by the electric battery 600, the driven member 488 is kept in the disengaged position. When the electric power is cut off, the driven member 488 is automatically moved in the engaged position by the spring 489. The powering of the electric actuator 490 may be controlled by the ECU 450 using a map or a model that receives as in-puts a value of an engine torque and a value of an engine speed, and which returns as output whether the electric actuator 490 should be powered-on or powered-off.

The NGU 500 is an electric machine, namely an electro-mechanical energy converter, which is able either to convert electricity sup-plied by the battery 600 into mechanical power (i.e., to operate as an electric motor) or to convert mechanical power into electricity that charges the battery 600 (i.e., to operate as electric genera-tor). In greater details, the MGIJ 500 may comprise a rotor, which is arranged to rotate with respect to a stator, in order to generate or respectively receive the mechanical power. The rotor may comprise means to generate a magnetic field and the stator may comprise elec-tric windings connected to the battery 600, or vice versa. When the MGU 500 operates as electric motor, the battery 600 supplies electric currents in the electric windings, which interact with the magnetic field to set the rotor in rotation. Conversely, when the MGU 500 op- erates as electric generator, the rotation of the rotor causes a rel-ative movement of the electric wiring in the magnetic field, which generates electrical currents in the electric windings. The MGU 500 may be of any known type, for example a permanent magnet machine, a brushed machine or an induction machine. The MGU 500 may also be ei-ther an asynchronous machine or a synchronous machine.

The rotor of the MGU 500 may comprise a coaxial shaft 505, which is mechanically is connected with other components of the hybrid power-train 100, so as to be able to deliver or receive mechanical power to and form the final drive of the motor vehicle. In this way, operating as an electric motor, the PIGU 500 can assist or replace the ICE 110 in propelling the motor vehicle, whereas operating as an electric ge-nerator, especially when the motor vehicle is breaking, the MGU 500 can charge the battery 600. In the present example, the MW shaft 505 is connected with the ICE crankshaft 145 through a transmission belt 510, similarly to a conventional alternator starter. In order to switch between the motor operating mode and the generator operating mode, the MGU 500 may be equipped with an appropriate internal con-trol system.

Turning now to the ECU 450, this apparatus may include a digital cen-tral processing unit (CPU) in corununication with a memory system 460 and an interface bus. The memory system 460 may include various sto-rage types including optical storage, magnetic storage, solid state storage, and other non-volatile memory. The interface bus may be con-fiqured to send, receive, and modulate analog and/or digital signals to/from the various sensors and control devices. The CPU is conf i- guxed to execute instructions stored as a program in the memory sys-tern 460, and send and receive signals to/from the interface bus. The program may errbody the methods disclosed herein, allowing the CPU to carryout out the steps of such methods and control the ICE 110 and the MGU 500. 7.

In order to carry out these methods, the ECU 450 is in corrgnunication with one or more sensors and/or devices associated with the ICE 110, the MCU 500 and the battery 600. The ECU 450 may receive input sig- nals from various sensors configured to generate the signals in pro-portion to various physical parameters associated with the ICE 110, the MGU 500 and the battery 600. The sensors include, but are not li- mited to, a mass airf low and temperature sensor 340, a manifold pres-sure and temperature sensor 350, a combustion pressure sensor 360, coolant and oil temperature and level sensors 380, a fuel rail pres- sure sensor 400, a camshaft position sensor 410, a crankshaft posi-tion sensor 420, exhaust pressure and temperature sensors 430, an EGR temperature sensor 440, a sensor 445 of a position of an accelerator pedal 446, and a measuring oircuit 605 capable of sensing the state of charge of the battery 600. FUrthermore, the ECU 450 may generate output signals to various control devices that are arranged to con-trol the operation of the ICE 110 and the MGU 500, including, but not limited to, the fuel injectors 160, the throttle body 330, the EGR valve 320, the VGT actuator 290, the cam phaser 155, and the above mentioned internal control system of the MGU 500. Note, dashed lines are used to indicate connunication between the ECU 450 and the vari-ous sensors and devices, but some are omitted for clarity.

According to the present embodiment, the ICE 110 and the DIGU 500 are controlled by the ECU 450 according an Hybrid Operating Strategy (HOS). During the propulsion of the motor vehicle, the HOS provides for continuously repeating the routine which is shown in the f low-chart of figure 2, and which comprises the essential steps of: -determining (block 10) an overall value F0 of mechanical power to be delivered to the final drive of the motor vehicle by the hybrid powertrain as a whole, -splitting (block 20) this overall value P in a contributing value P of mechanical power to be requested to the ICE 110, and a ccntributing value F of mechanical power to be re-quested to the NGU 500, and then of -operating (block 30) the ICE 110 to deliver the contributing value Pj of mechanical power, and the MGU 500 to deliver con-tributing value P of mechanical power.

In the present example, where the MGU shaft 505 is mechanically con-nected with the final drive of the motor vehicle through the ICE crankshaft 145, the value P could alternatively indicate the overall mechanical power to be delivered to the ICE crankshaft 145 itself. In that case, also the contributing values P1 and P would be referred to the ICE crankshaft 145.

The overall value P may be determined by the ECU 450 on the basis of the position of the accelerator pedal 446, which can be measured by the accelerator pedal position sensor 445.

The splitting of the overall value P0 may be performed by the ECU 450 with the aid of a predetermined polynomial function, hereafter re-ferred as target function, that quantifies the overall power losses FL of the hybrid powertrain 100, on the basis of an unknown value x of mechanical power to be delivered by the ICE 110 and an unknown value y of mechanical power to be delivered by the MGU 500: = f(x, i-') In other words, the unknown value x and y are variables of the target function f (x, y). The predetermined target function f (x, y) may be stored in the memory system 460 associated to the ECU 450.

More particularly, the 1-lOS provides for the ECU 450 to determine, among the infinite couples of power values (x. y) which satisfy the equation: the specific couple of power values which also minimize the target function, namely which minimize the value PL of the overall power losses of the hybrid powertrain 100.

The power values of the so determined couple are then respectively assumed as ICE contributing value (P) and as GU contributing value so that the contributing values P) satisfies both the following oondit ions: = + -IIgu = minf(x,y).

Two alternative approaches are known and may be used by the ECU 450 to determine the couple of power values (Pj, P) which minimize the target function f(x, y): a step-by-step approach or an integral ap-proach.

It should be understood that the contributing value P of the MGU 500 may result either positive or negative. If the contributing value P is positive, it means that the MW 500 is requested to operate as an electric motor that delivers torque to the final drive of the motor vehicle. If the contributing value P is negative, it means that the MCU 500 is requested to operate as an electric generator that charges the battery 600.

According to the present exthodiment, the target function may be de-scribed by the following equation: FL,0, =f(x,y)=F1 +F2 +F -i-F4 +P +F wherein F1, ..., F6 are the so called terms of the polynomial target func-tion.

The first term F1 of the target function may be described by the fol-iowing equation: = . PL, wherein k1 is a constant and PL1 is a value that quantifies the power lost by the ICE 110, as a difference between the energy of the spent fuel and the energy aotually delivered by the ICE 110 to the final drive of the motor vehicle. The value PL1 may be calculated according to the following equation: PLke = Il -x =(1-uiYQ, *H1 so that: F1 = PL, = . (H. -= . [(1 -H I wherein H1 is the value of the heat of combustion of the fuel, Q is the value of the mass flow of fuel injected into the ICE 110 X ±5 the unknown value of mechanical power to be delivered by the ICE 110, and q is the value of an efficiency parameter that accounts for both the thermo-mechanical efficiency of the ICE 110 and the friction loss in the kinematical chain connecting the ICE 110 to the final drive of the motor vehicle.

The second term F2 of the target function may be described by the fol-lowing equation: F., = . wherein Jc2 is a constant and PL1,1 is a value that quantifies an addi-tional amount of power that is lost by the ICE 110 due a possible slowing down of the ICE warm-up phase caused by the operation of the MGU 500 and vice versa. The value PLr,± may be calculated according to the following equation: ( P L icC,WurJfl Tic, T T k ice, warn: -ice,culd) so that: F2 = k2 PLTk, = ( T1ç warn: -cc]2 Tke wan: -cc,cokI wherein is a nominal value of the ICE temperature after the completion of the warm-up phase, is a nominal value of the ICE temperature before the want-up phase, is an actual value of the ICE temperature, and is the power supplied by the battery 600.

The nominal values and T±,ld can be determined during art expe-rimental activity and stored in the memory system 460 associated with the ECU 450; the actual value T1 can be measured with the aid of one or more of the temperature sensor of the ICE, including, but not li-mited to, the manifold temperature sensor 350, the coolant and oil temperature sensors 380, and the exhaust temperature sensors 430; the value P can be determined from the voltage and current absorption of the MGI,) 500.

The third term F of the target function may be described by the fol-lowing equation: F, = wherein Ic3 is a constant and PI is a value that quantifies the power lost by the MGU 500, as a difference between the chemical energy of the battery 600 and the energy actually delivered by the MW 500 to the final drive of the motor vehicle, thereby taking into account the chemical efficiency of the battery 600, the electromechanical effi-ciency of the MOO 500 and the friction loss in the kinematical chain connecting the MOO 500 to the final drive of the motor vehicle. The value PI may be calculated according to the following equation: = -Y = I -y so that: = PL,,,,, = -y) = (1* - wherein is a value of an electric power generated by the bat-tery 600, I is a value an electric current absorbed by the MOO 500, Vo is a value of a tension measured at battery 600 poles at open cir-cuit, and y is the unknown value of mechanical power to be delivered by the MOO 500. The values I and V can be determined by measuring MGU 500 current and battery 600 voltage characteristics.

The fourth term F4 of the target function may be described by the fol-lowing equation: = wherein Ic4 is a constant and PL is a value that quantifies a ficti-tious increase/decrease of power loss, which is introduced if the current value of the state of charge (SOC) of the battery 600 exits from a predetermined range of allowable values thereof. The current SOC value can be determined through the measuring circuit 605. The range of allowable values may be stored in the memory system 460 as-sociated with the ECU 450. The value PL may be calculated according to the following equation: = c1'i so. --v/gil so that: F4 = PL = [c, -(Ph,,,, -h,,ii 4ift wherein C1, is a value of a non-dimensional quantity comprised be-tween -1 and ÷1, which is used to target the battery 600 state of charge within the acceptable range, P\ is a value of actual power absorbed or released by the battery 600, Pttt,sft is a fictitious val- ue of battery power used to target the ideal state of charge of bat- tery 600. The values C1,, tt,tft can be determined by a proper ca-libration activity, whereas P can be determined from the current and voltage measurement on the MGTJ 500.

The fifth term F5 of the target function takes into account the noise generated by the corrbustion processes within the ICE 110. The fifth term F5 may be described by the following equation: F = . wherein k5 is a constant and is a value of an acoustic power of the ICE coritustion noise. The acoustic power value Pj may be deter-mined on the basis of the unknown value x of mechanical power to be delivered by the ICE 110. More particularly, the acoustic power value noise may be determined on the basis of a value of engine torque, which depends on the unknown value x of mechanical power according to well known models or maps implemented in the ECU 450, and on the ba-sis of a value of engine speed, which can be measured by the ECU 450 with the aid of the crankshaft position sensor 420. By way of exam-ple, the acoustic power value Pise may be determined by means of a map which receives as inputs the above mentioned engine torque value and engine speed value, and which return as output a corresponding acoustic power value F1, of the combustion noise of the ICE 110. The map can be empirically calibrated and then stored in the memory sys- tem 460 associated with the ECU 450. The use of the logarithmic ap-proach is consistent with the way the occupants of the motor vehicle perceive the noise discomfort.

Thanks to this fifth term F5 of the target function, the HOS can ad-vantageously increase the MGU contributing value P rather than the ICE contributing value Pj, whenever the combustion noise could become too annoying for the vehicle occupants, for example when a vehicle drive away or an acceleration.

The sixth term Es takes into account the operating state of the switchable coolant pump 475.

The value of the sixth term F5 is set to zero, whenever the switchable coolant pump 475 is expected to be switched-off, and it is evaluated, whenever the switchable coolant pump 475 is expected to be switched-on.

The switchable coolant pump 475 may be determined to be switched-off or switched-on depending on the unknown value x of the mechanical power to be delivered by the ICE 110. More particularly, this deter-mination may be performed on the basis of a value of engine torque, which depends on the unknown value x of mechanical power according to well known models or maps implemented in the ECU 450, and on the ba-sis of a value of engine speed, which can be measured by the ECU 450 with the aid of the crankshaft position sensor 420. As a matter of fact, this determination may be performed using the map or model which has been described to be used by the ECU 450 to control the po-wering of the electric actuator 490.

When the switchable coolant pump 475 is expected to be switched-on, the sixth terms F5 may be calculated according to the following equa-tion: = . PL, wherein k6 is a constant and PL is a value that quantifies a power lost by the hybrid powertrain 100 for operating the switchable coo- lant pump 475. The value PL may be calculated according to the fol-lowing equation: = -hp.eI + 77t,,gTA so that: P6 = PL = k6 -wp,cI + ii "Sn wherein is a value of the mechanical power spent by the ICE 110 to drive the switchable coolant pump 475, when the latter is switch-ed-on, is a value of the electrical power spent by the battery 600 to power-on the electric actuator 490, when the switchable coo- lant pump 475 is switched-off, apLfrjc,Tl is a value of a difference be-tween the power lost by the ICE 110, due to mechanical friction, when the switchable coolant pump 475 is switched-on and the power lost by the ICE 110, due to mechanical friction, when the switchable coolant pump 475 is switched-off. In fact, if the switchable coolant pump 475 is switched-off, the coolant does not pass through the radiator 430, so that the engine temperature is greater (about 105°C) than if the switchable coolant pump 475 is switched-on and the coolant actually passes through the radiator 480 (about 95°C). This variation of en-gine temperature causes a variation of the viscosity of the lubricant (oil) that is used to lubricate the moving parts of the ICE 110. As a consequence the ICE friction losses are generally a little lower when the switchable coolant pump 475 is switched-off rather than when it is switched-on. The value APLf,1 quantifies this variation of the ICE friction losses due to the lubricant viscosity variation.

The value the value 2,e1 and the value APLftIC,T1 can be empiri-cally determined and stored in the memory system 460 associated with the ECU 450.

It should be understood that the proposed expression of the value PL takes into almost all the power losses caused by the activation of the switchable coolant pump 475, but a rough evaluation of these ad-ditional power loss could also be achieved by considering only one or two of the preceding values Pw,el and &Lfric,T1.

From the above it follows that, thanks to the sixth term F6 of the target function, the BbS can advantageously take into account the power losses due to the cperation of the switchable coolant pump 475, thereby optimizing the splitting of the overall value P into the ICE contributing value Pj and the P4GU contributing value P. The value of the constants ki, k2, k3, k4, k5 and k6 involved in the target function are empirically calibrated and stored in the memory system 460 associated to the ECU 450.

While at least one exemplary embodiment has been presented in the foregoing summary and detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only exam- ples, and are not intended to limit the scope, applicability, or con- figuration in any way. Rather, the forgoing summary and detailed de-scription will provide those skilled in the art with a convenient road map for implementing at least one exemplary embodiment, it being understood that various changes may be made in the function and ar-rangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and in their legal equivalents.

BEEEREWS block block

30 block hybrid powertrain internal combustion engine engine block cylinder 130 cylinder head camshaft piston crankshaft combustion chamber 155 cam phaser fuel injector fuel rail fuel pump fuel source 200 intake manifold 205 air intake pipe 210 intake port 215 valves 220 exhaust port 225 exhaust manifold 230 turbocharger 240 compressor 250 turbine 260 intercooler 270 exhaust system 275 exhaust pipe 280 aftertreatment devices 290 VGT actuator 300 exhaust gas recirculation system 310 EGR cooler 320 EGR valve 330 throttle body 340 mass airflow and temperature sensor 350 manifold pressure and temperature sensor 360 in-cylinder pressure sensor 380 coolant and oil temperature and level sensors 400 fuel rail pressure sensor 410 camshaft position sensor 420 crankshaft position sensor 430 exhaust pressure and temperature sensors 440 EGR temperature sensor 445 accelerator pedal position sensor 446 accelerator pedal 450 ECU 460 memory system 470 engine coolant circuit 475 switchable coolant pump 480 radiator 485 clutch 486 driving member 487 transmission belt 488 driven member 489 spring 490 electric actuator 500 motor-generator electric unit 505 MGU shaft 510 transmission belt 600 battery 605 measuring circuit