GB2493747A - A method for operating a hybrid powertrain - Google Patents

A method for operating a hybrid powertrain Download PDF

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Publication number
GB2493747A
GB2493747A GB1114160.3A GB201114160A GB2493747A GB 2493747 A GB2493747 A GB 2493747A GB 201114160 A GB201114160 A GB 201114160A GB 2493747 A GB2493747 A GB 2493747A
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United Kingdom
Prior art keywords
value
power
ice
mgu
coolant pump
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GB1114160.3A
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GB201114160D0 (en
Inventor
Alberto Vassallo
Claudio Ciaravino
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GM Global Technology Operations LLC
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GM Global Technology Operations LLC
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Priority to GB1114160.3A priority Critical patent/GB2493747A/en
Publication of GB201114160D0 publication Critical patent/GB201114160D0/en
Publication of GB2493747A publication Critical patent/GB2493747A/en
Withdrawn legal-status Critical Current

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60WCONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W20/00Control systems specially adapted for hybrid vehicles
    • B60W20/10Controlling the power contribution of each of the prime movers to meet required power demand
    • B60W20/15Control strategies specially adapted for achieving a particular effect
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60WCONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W10/00Conjoint control of vehicle sub-units of different type or different function
    • B60W10/04Conjoint control of vehicle sub-units of different type or different function including control of propulsion units
    • B60W10/06Conjoint control of vehicle sub-units of different type or different function including control of propulsion units including control of combustion engines
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60KARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K6/00Arrangement or mounting of plural diverse prime-movers for mutual or common propulsion, e.g. hybrid propulsion systems comprising electric motors and internal combustion engines ; Control systems therefor, i.e. systems controlling two or more prime movers, or controlling one of these prime movers and any of the transmission, drive or drive units Informative references: mechanical gearings with secondary electric drive F16H3/72; arrangements for handling mechanical energy structurally associated with the dynamo-electric machine H02K7/00; machines comprising structurally interrelated motor and generator parts H02K51/00; dynamo-electric machines not otherwise provided for in H02K see H02K99/00
    • B60K6/20Arrangement or mounting of plural diverse prime-movers for mutual or common propulsion, e.g. hybrid propulsion systems comprising electric motors and internal combustion engines ; Control systems therefor, i.e. systems controlling two or more prime movers, or controlling one of these prime movers and any of the transmission, drive or drive units Informative references: mechanical gearings with secondary electric drive F16H3/72; arrangements for handling mechanical energy structurally associated with the dynamo-electric machine H02K7/00; machines comprising structurally interrelated motor and generator parts H02K51/00; dynamo-electric machines not otherwise provided for in H02K see H02K99/00 the prime-movers consisting of electric motors and internal combustion engines, e.g. HEVs
    • B60K6/42Arrangement or mounting of plural diverse prime-movers for mutual or common propulsion, e.g. hybrid propulsion systems comprising electric motors and internal combustion engines ; Control systems therefor, i.e. systems controlling two or more prime movers, or controlling one of these prime movers and any of the transmission, drive or drive units Informative references: mechanical gearings with secondary electric drive F16H3/72; arrangements for handling mechanical energy structurally associated with the dynamo-electric machine H02K7/00; machines comprising structurally interrelated motor and generator parts H02K51/00; dynamo-electric machines not otherwise provided for in H02K see H02K99/00 the prime-movers consisting of electric motors and internal combustion engines, e.g. HEVs characterised by the architecture of the hybrid electric vehicle
    • B60K6/48Parallel type
    • B60K6/485Motor-assist type
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60WCONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W10/00Conjoint control of vehicle sub-units of different type or different function
    • B60W10/04Conjoint control of vehicle sub-units of different type or different function including control of propulsion units
    • B60W10/08Conjoint control of vehicle sub-units of different type or different function including control of propulsion units including control of electric propulsion units, e.g. motors or generators
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60WCONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W10/00Conjoint control of vehicle sub-units of different type or different function
    • B60W10/30Conjoint control of vehicle sub-units of different type or different function including control of auxiliary equipment, e.g. air-conditioning compressors or oil pumps
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60WCONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W20/00Control systems specially adapted for hybrid vehicles
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60WCONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W20/00Control systems specially adapted for hybrid vehicles
    • B60W20/10Controlling the power contribution of each of the prime movers to meet required power demand
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60WCONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W50/00Details of control systems for road vehicle drive control not related to the control of a particular sub-unit, e.g. process diagnostic or vehicle driver interfaces
    • B60W2050/0001Details of the control system
    • B60W2050/0019Control system elements or transfer functions
    • B60W2050/0028Mathematical models, e.g. for simulation
    • B60W2050/0037Mathematical models of vehicle sub-units
    • B60W2050/0039Mathematical models of vehicle sub-units of the propulsion unit
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02TCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00Road transport of goods or passengers
    • Y02T10/60Other road transportation technologies with climate change mitigation effect
    • Y02T10/62Hybrid vehicles

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Automation & Control Theory (AREA)
  • Hybrid Electric Vehicles (AREA)
  • Control Of Vehicle Engines Or Engines For Specific Uses (AREA)
  • Electric Propulsion And Braking For Vehicles (AREA)

Abstract

A method for operating a hy­brid powertrain 100 comprising an internal combustion engine (ICE) 110 and a motor-generator electric unit (MGU) 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 ICE 110 and an unknown value y of power to be delivered by the MGU 500, to determine a contributing value Pice, of power to be requested to the ICE and a contributing value Pmgu of power to be requested to the MGU 500; and operating the ICE 110 and the MGU 500 to deliver the respective contributing value of power Pice, Pmgu; the predetermined polynomial function comprising a term whose value depends on a value PLswp of a power lost by the hybrid powertrain 100 for operating a switchable coolant pump 475, if the switchable coolant pump 475 is switched-on, and is zero if the switchable coolant pump is switched off.

Description

HETHCD FOR OPERATING A HYBRID PC*ERTPA2'1 TEQ1ICL FflD The present invention relates to a method for operating a hybrid p0-wertrain of a motor vehicle.
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), and a motor-generator electric unit (NGU). 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 MGU are controlled by an electronic control unit (ECU) according to a Hybrid cperating 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 MGU, and then for operating the ICE and the MCU 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 NGU 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 terra, 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 MOO 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 MGU 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 HOS arises when the ICE is equipped with a switcha-ble coolant pump. The switchable coolant pump is usually ethodied as a conventional mechanical pump having the peculiarity of being con-nected 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 disen-gaged 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 actuator, which is connected with the electric battery of the hybrid powertrain. As long as the electric actuator is powered by the electric battery, the clutch is kept in the disengaged position; a spring being provided for moving the clutch in the engaged posi-tion, when the electric actuator is powered-off. The powering of the electric actuator is controlled by the ECU on the basis of one or more operating parameter of the ICE, typically on the basis of the engine torque and engine speed.
In view of the above, it follows that the overall power lost by the hybrid powertrain equipped with a switchable coolant pump depends al-so on whether the switchable coolant pump is actually switched-on or switched-off. However, the conventional HOS is completely insensitive to this aspect, so that there can be cases in which the HOS deter- mines an ICE power contribution that is not the optimal one for mini-mizing the overall power loss of the hybrid powertrain, for example because the determined ICE power contrThution could cause the switch- able pump to switch-on whereas it could be better to keep the switch- able coolant pump switched-off and increasing the MGU power contribu-tion.
An object of an entodinent 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.
DISCLOSURE
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 combustion en- gine (ICE) and a motor-generator electric unit (MGU), 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 MGJJ, to determine a contributing value of power to be requested to the ICE and a contributing value of power to be requested to the MGU, and - -operating the ICE and the MJ to deliver the respective contri-buting value of power, and wherein the predetermined polynomial equation comprises a 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.
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 advantageously into account the power lost by the switchable coolant pump, thereby determining an ICE power contribu-tion 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 switohable 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 term of the target function is correct- ly correlated to the unknown ICE power value, thereby further opti-mizing the determination of the ICE power contribution and the D'IGU 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 combustion 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 I-lOS.
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.
According to another aspect of the invention, the predetermined poly-nomial equation (target function) further comprises an additional term whose value depends on a value of an acoustic power of a corribus-tion noise generated by the ICE.
This aspect of the invention has the advantage of improving the Noise, Vibration and Harshness (NVH) comfort level of the motor ve- hicle. The NVH comfort level is a parameter that evaluates the over-all amount of noise and vibration that is perceived by the occupants of the motor vehicle. 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 aero-dynamic 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 vehicle is low, the aerodynamic noise and the tire-rolling noise are almost irrelevant, so that the ICE combustion noise becomes the most worsening factor of the NVH comfort level. As a consequence, in order to improve the NW comfort level in this conditions, it could sometimes be better to reduce the combustion noise by reducing the ICE power contribution and by correspondently increasing the MW power contribution.
The last mentioned aspect of the invention has the advantage of al- lowing the HOS to perform this optimization, namely to take into ac- count also the combustion noise of the ICE, so as to be able of in- creasing the MGU power contribution rather than the ICE power contri-bution whenever the combustion noise could become too annoying for the vehicle occupants, for example when the hybrid powertrain is re-quested to accelerate the motor vehicle starting from a low vehicle speed.
According to an aspect of the invention, the value of the above named additional term particularly depends on the logarithm of the acoustic power value of the ccmbustion 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 combustion 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 additional term is cor- rectly correlated to the unknown ICE power value, thereby further op-timizing 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.
The methods according to the invention can be carried out 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 electromagnetic signal, said signal being modulated to carry a sequence of data bits which represent a computer program to carry out all steps of the method.
Another embodiment of the present invention provides an apparatus for operating a hybrid powertrain comprising an ICE and a MGU, 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-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 1GU to deliver the respec-tive contributing value of power, and wherein the predetermined polynomial equation comprises a terra 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.
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 the power lost by the switchable coo-lant pump, thereby determining an ICE power contribution 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.
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 unl.a-iown value of power to be delivered by the MGU, 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 equation comprises a 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 switcha-ble coolant pump is switched-on.
Also this eitodiment of the invention has the advantage of the method disclosed above, particularly that of allowing the hybrid operating strategy to take into account the power lost by the switchable coo-lant pump, thereby determining an ICE power contribution 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.
BRflF DESCfl2TIC4 Ok' 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-ing to the hybrid powertrain of figure 1.
Figure 4 is a section A-A of the internal combustion engine of figure 3.
DEILTh DESCBIPTICN 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 MGCJ 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 chain- 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 injector from a fuel rail 170 in fluid communication 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 cantshaft 135 rotating in time with the crankshaft 145. The valves 215 selectively allow air into the combustion chamber 150 from the port 210 and alternately allow exhaust gases to exit through at least one exhaust port 220. In some examples, a cam phaser 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 ex-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 cornposi-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-berg, selective catalytic reduction (SCR) 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.
M 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-under 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 48, 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 F4GU 503 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 MGU 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 wind.inqs. The NGU 500 may be of any known type, for example a permanent magnet machine, a brushed machine or an induction machine. The [CU 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 £43U 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 [CU 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 NGU 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 conmunication 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-figured to send, receive, and modulate analog and/or digital signals to/from the various sensors and control devices. The CPU is conf 1- gured to execute instructions stored as a program in the memory sys-tem 460, and send and receive signals to/from the interface bus. The program may embody the methods disclosed herein, allowing the Cpu to carryout out the steps of such methods and control the ICE 110 and the ?4GU 500.
In order to carry out these methods, the ECU 450 is in comunication with one or more sensors and/or devices associated with the ICE 110, the MSU 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 airflow and terperature 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 terrperature sensor 440, a sensor 445 of a position of an accelerator pedal 446, and a measuring circuit 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 EGS Valve 320, the VOT actuator 290, the cam phaser 155, and the above mentioned internal control system of the MGU 500. Note, dashed lines are used to indicate conmunication 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 MGU 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 2tot 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 P1 of mechanical power to be requested to the ICE 110, and a contributing value P of mechanical power to be re-quested to the MOO 500, and then of -operating (block 30) the ICE 110 to deliver the contributing value P1 of mechanical power, and the MGU 500 to deliver con-tributing value P of mechanical power.
In the present example, where the MOO shaft 505 is mechanically con-nected with the final drive of the motor vehicle through the ICE crankshaft 145, the value P0 could alternatively indicate the overall mechanical power to be delivered to the ICE crankshaft 145 itself. In that case, also the contributing values F1 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 P 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 FL0 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, .) -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 I-lOS provides for the ECU 450 to determine, among the infinite couples of power values (x, y) which satisfy the equation: p = + the specific couple of power values which also minimize the target function, namely which minimize the value 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 MGU contributing value so that the contributing values P) satisfies both the following conditions: = + f(PjceJ'jqçj)=IMflf(X.Y) Two alternative approaches are known and may be used by the ECU 450 to determine the couple of power values 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 MGO 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 MGU 500 is requested to operate as an electric generator that charges the battery 600.
According to the present embodiment, the target function may be de-scribed by the following equation: P4,,, =f(x,y)=F1+F2+F3+F4+F5+F6 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-lowing equation: F1 = . 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 actually delivered by the ICE 110 to the final drive of the motor vehicle. The value PL may be calculated according to the following equation: PLace = II, Qi -= (1 77). Q11 H, so that: F1 =Ic *PL ice = k.(H.Q1 -P,.)=k, {(l-T/)Qfd H,] wherein H is the value of the heat of coithustion of the fuel, Qe is the value of the mass flow of fuel injected into the ICE 110, x is the unknown value of mechanical power to be delivered by the ICE 110, and r 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: F2 = k1 *PJJ,, wherein Ic2 is a constant and PL11 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 may be calculated according to the following equation: FL -ICC,WUfl,i ICC 7Jce T ce,warm -ice,coW 1 so that: (r. -Tt = PI#j*jc = ,Ct,wciru, i -cecoId} wherein is a nominal value of the ICE temperature after the completion of the warm-up phase, T±,c is a nominal value of the ICE temperature before the warm-up phase, is an actual value of the ICE temperature, and P is is the power supplied by the battery 600. The nominal values and Tj,w1d can be determined during an experimental 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 limited to, the manifold terrperature sensor 350, the coolant and oil tert-perature sensors 380, and the exhaust temperature sensors 430; the value can be determined from the voltage and current absorption of the £4GIJ 500.
The third term F3 of the target function may be described by the fol-lowing equation: F, = k3 wherein k3 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 MGU 500 to the final drive of the motor vehicle, thereby taking into account the chemical efficiency of the battery 600, the electromechanical eff i-ciency of the MGJ 500 and the friction loss in the kinematical chain connecting the MGU 500 to the final drive of the motor vehicle. The value PL4 may be calculated according to the following equation: = T'clwu,,hai, -Y = -Y so that: F3 = - = . h,,, -y) = k3 (1 -Y) wherein is a value of an electric power generated by the bat-tery 600, I is a value of an electric current absorbed by the MGU 500, V, is a value of a tension measured at battery 600 poles at open circuit, and y is the unknown value of mechanical power to be deli- vered by the MOO 500. The values I arid V can be determined by mea-suring MGU 500 current and battery 600 voltage characteristics.
The fourth term F4 of the target function may be described by the fol-lowing equation: F4 = k4 - wherein 1c4 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: PL1 = - -.vh) so that: F4 = k4 = k4 --huIf.sliffi wherein Ci, is a value of a non-dimensional quantity convrised 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, is a fictitious val- ue of battery power used to target the ideal state of charge of bat- tery 600. The values C1,, B.Dtt,sjuft can be determined by a proper ca-libration activity, whereas P can be determined from the current and voltage measurement on the P'GU 500.
The fifth term F5 of the target function takes into account the noise generated by the combustion processes within the ICE 110. The fifth term F5 may be described by the following equation: F5 = k5 Log(P,,.) wherein k5 is a constant and 2floe is a value of an acoustic power of the ICE combustion noise. The acoustic power value jse 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 Pnojse 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 cf the crankshaft position sensor 420. By way of exam-plc, the acoustic power value j5e 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 2flQjse 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 P1, whenever the cortustion noise could become too annoying for the vehicle occupants, for example when a vehicle drive away or an acceleration.
The sixth term F'6 takes into account the operating state of the switchable coolant pump 475.
The value of the sixth term F'6 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 F6 may be calculated according to the following equa-tion: = 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 PL3 may be calculated according to the fol-lowing equation:
H CI
= wp piece -+ APL so that: F6 = = 1mmecc -WP,CI + SPLIVIC wherein PM,, 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, Pw,ei 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, PLjc,T1 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 480, 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 APLfrjc,T1 quantifies this variation of the ICE friction losses due to the lubricant viscosity variation.
The value the value and the value apLfric,T1 can be ei-rpiri-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 PLgtp 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 and apLiric,ii.
From the above it follows that, thanks to the sixth term F6 of the target function, the 1-103 can advantageously take into account the power losses due to the operation of the switchable coolant pump 475, thereby optimizing the splitting of the overall value P0 into the ICE contributing value P and the MGU contributing value P. The value of the constants kl, 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 exeirpiary 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 surmiary and detaiied 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. 2B
REFZRENES 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 punp 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 VCT 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 menter 487 transmission belt 488 driven member 489 spring 490 electric actuator 503 motor-generator electric unit 505 MOO shaft 510 transmission belt 600 battery 605 measuring circuit
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2515776A (en) * 2013-07-01 2015-01-07 Gm Global Tech Operations Inc Method of controlling a hybrid powertrain

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JP2008001301A (en) * 2006-06-26 2008-01-10 Mazda Motor Corp Controller of hybrid vehicle
US20080228351A1 (en) * 2007-03-12 2008-09-18 Mc Gee Gary E Speed-limiting accessory drive system and method of controlling speed of a driven accessory

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008001301A (en) * 2006-06-26 2008-01-10 Mazda Motor Corp Controller of hybrid vehicle
US20080228351A1 (en) * 2007-03-12 2008-09-18 Mc Gee Gary E Speed-limiting accessory drive system and method of controlling speed of a driven accessory

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2515776A (en) * 2013-07-01 2015-01-07 Gm Global Tech Operations Inc Method of controlling a hybrid powertrain

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