GB2525538A

GB2525538A - Method of controlling a cooling system of an internal combustion engine

Info

Publication number: GB2525538A
Application number: GB1514391.0A
Authority: GB
Inventors: Francesco Barba; Simone Bambagioni; Alessandro Gallone
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2015-08-13
Filing date: 2015-08-13
Publication date: 2015-10-28
Also published as: GB201514391D0

Abstract

A cooling system 500 of an internal combustion engine 110 comprises a coolant pump 520 and a cooling jacket 530 passing through an engine body 115. The cooling jacket 530 receives a coolant from the coolant pump 520. An amount of heat energy transferred from the engine body 115 to the coolant through the cooling jacket 530 is determined from engine speed and torque. A temperature increment of the coolant is calculated as a function of the determined amount of the heat energy, and a value of the coolant temperature determined from the calculated temperature increment. A value of a heat capacity of the engine body 115 may be calculated and used with a heat capacity of the coolant to calculate the temperature increment. A correction factor may be determined from the determined coolant temperature. The speed of the coolant pump 520 may be regulated based on the coolant temperature and a sensor 535 may be used to calculate the difference between measured and determined coolant temperatures to identify a malfunction of the sensor 535.

Description

S METHOD OF CONTROLLING A COOLING SYSTEM OF AN INTERNAL

COMBUSTION ENGINE

TECHNICAL FIELD

The present disclosure relates to a method of controlling a cooling system of an internal combustion engine, in particutar of an internal combustion engine (e.g. gasoline engine or Diesel engine) of a motor vehicle.

BACKGROUND

Powertrains of vehicles generate heat and typically, a cooling system having a circulating coolant is provided to cool the powertrain. During warm-up phase, after a cold start of the powertrain, the temperature increment of the coolant needs to be monitored and managed to ensure the cooling system properly operate. In order to monitor the temperature increment of the coolant a temperature sensor, which continuously senses the temperature of the coolant, is generally provided in the cooling system. However, the coolant temperature sensor represents an additional cost that the car makers would like to save and the proper functioning of the coolant temperature sensor and/or the proper monitoring of the coolant temperature, in any case, has to be guaranteed for thermal management purposes of the cooling system.

SUMMARY

In view of the above, an object of the present disclosure is that of providing a strategy for determining the coolant temperature during the warm-up without using temperature sensors.

Another object is that of reaching this goal with a simple, rational and rather inexpensive solution.

These and other objects are achieved by a solution having the features reported in the independent claim. The features reported in the dependent claims represents auxiliary aspect of the solution.

An embodiment of the disclosure provides a method of controlling a cooling system of an internal combustion engine, wherein the cooling system comprises a coolant pump, a cooling jacket passing through an engine body and receiving a coolant from the coolant pump, wherein the method comprises the steps of: -determining an amount of heat energy transferred from the engine body to the coolant through the cooling jacket on the basis of an engine speed and an engine torque of the internal combustion engine; -calculating an increment of a temperature of the coolant as a function of the determined amount of the heat energy; and -determining a value of the coolant temperature on the basis of the calculated increment.

Thanks to this solution a precise determination of the temperature of the coolant during the warm-up of the internal combustion engine may be obtained without using coolant (or metal) temperature sensors and however independently to their presence in the cooling system. Therefore a cost reduction for the car makers, due to the possible removal of the temperature sensors from the cooling system layouts, may be achieved and a possibility to test the proper functioning of a coolant temperature sensor, if otherwise present, may be given as an example by means of a simple comparison between the measured temperature performed by the sensor and the determined temperature.

S

According to an embodiment, the method may comprise the steps of: -calculating a value of an heat capacity of the engine body; -using the calculated value of the heat capacity and a value of an heat capacity of the coolant for calculating the increment.

In this way, it is provided a simple and reliable solution for calculating the increment requiring few calibration effort and few computation power.

According to an embodiment of the invention, the method may further comprise the steps of: is -calculating a maximum value of the heat capacity of the engine body on the basis of a value of a mass of the engine body and a value of a specific heat of a material of which the mass of the engine body is made; -determining a correction factor on the basis of the determined value of the coolant temperature; and -calculating the value of the heat capacity as a function of the maximum value and the correction factor.

Preferably, the correction factor may be calculated with the following formula: k = 0.0629 * e (C.0557'fl, wherein k is the correction factor and T is the determined coolant temperature (in Celsius degrees), if the determined value of the coolant temperature is smaller than a determined threshold value thereof.

Otherwise, the correction factor is set as equal to 1, if the determined value of the coolant temperature gets equal to or larger than a determined threshold value thereof.

This correction factor is based on the assumption that as soon as the internal combustion engine is operated the mass of the engine body which transfers heat energy to the coolant is a small percentage of the overall mass of the engine body, namely a confined mass of the engine body which encompasses engine combustion chambers, and as the engine operates the percentage increases. Therefore this aspect of the solution may reduce the probability of false determinations, especially at the beginning of the operating phases of the internal combustion engine after cold start thereof, wherein the temperature of the coolant is lower than the predetermined threshold value thereof, thereby improving the reliability of the determination of the coolant temperature.

According to a further embodiment, the increment may be calculated with the following equation: AT=HR/(S+B), wherein, AT is the increment, HR is the determined amount of the heat energy, S is the calculated value of the heat capacity of the engine body and B is the value of the heat capacity of the coolant.

Thanks to this solution, the increment of temperature during the warm-up of the internal combustion engine may be calculated by means of a simple equation relating thermal energy to thermal mass.

According to an embodiment the method may comprise the step of operating a thermal management strategy of the cooling system on the basis of the determined value of the coolant temperature, by way of an example the thermal management strategy may comprise the step of regulating a speed at which the coolant pump operates on the basis of the determined value of the coolant temperature.

Thanks to this solution, the cooling system may be controlled, by way of an example modifying the speed and/or the paths of the coolant of the cooling system for optimizing engine and coolant warm-up after cold start thereof.

According to a further embodiment, wherein the cooling system comprises a coolant temperature sensor, the method may comprise the steps of: -measuring a value of the coolant temperature by means of the coolant temperature sensor; -calculating a difference between the determined value of the coolant temperature and the measured value of the coolant temperature; and -identifying a malfunctioning of the coolant temperature sensor, if the calculated difference gets equal to or greater than a predetermined threshold value thereof.

In this way, the determined coolant temperature may be used in a test strategy which may allow to diagnose the proper functioning of the coolant temperature sensor with few calibration effort and few computation power.

The proposed solution, achieving basically the same effects of the method described above, may be carried out with the help of a computer program comprising a program-code for carrying out, when run on a computer, 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.

s Another embodiment of the solution, achieving basically the same effects of the method described above, provides an internal combustion engine equipped with a cooling system comprising a coolant pump, a cooling jacket passing through an engine body of the internal combustion engine and receiving a coolant from the coolant pump, and an electronic control unit configured for carrying out the method above disclosed.

Another embodiment of the solution provides an apparatus for controlling a cooling system of an internal combustion engine, wherein the cooling system comprises a coolant pump, a cooling jacket passing through an engine body and receiving a coolant from the coolant pump, wherein the apparatus comprises: -means for determining an amount of heat energy transferred from the engine body to the coolant through the Cooling jacket on the basis of an engine speed and an engine torque of the internal combustion engine; -means for calculating an increment of a temperature of the coolant as a function of the determined amount of the heat energy; and -means for determining a value of the coolant temperature on the basis of the calculated increment.

According to an embodiment, the apparatus may comprise: -means for calculating a value of an heat capacity of the engine body; -means for using the calculated value of the heat capacity and a value of an heat capacity of the coolant for calculating the increment.

In this way it is provided a simple and reliable solution for calculating the increment requiring few calibration effort and few computation power.

According to an embodiment of the invention, the apparatus may further comprise: -means for calculating a maximum value of the heat capacity of the engine body on the basis of a value of a mass of the engine body and a value of a specific heat of a material of which the mass of the engine body is made; -means for calculating a correction factor on the basis of the determined value of the coolant temperature: and -means for calculating the value of the heat capacity as a function of the maximum value and the correction factor.

Preferably, the correction factor may be calculated with the following formula: k = 0.0629 * e (00557, wherein k is the correction factor and I (in Celsius degrees) is the determined value of the coolant temperature, if the determined value of the coolant temperature is smaller than a determined threshold value thereof.

This correction factor is based on the assumption that as soon as the internal combustion engine is operated the mass of the engine body which transfers heat energy S to the coolant is a small percentage of the overall mass of the engine body, namely a confined mass of the engine body which encompasses engine combustion chambers, and as the engine operates the percentage increases. Therefore this aspect of the solution may reduce the probability of false determinations1 especially at the beginning of the operating phases of the internal combustion engine after cold start thereof, wherein the temperature of the coolant is lower than the predetermined threshold value thereof, thereby improving the reliability of the determination of the coolant temperature.

According to a further embodiment, the increment may be calculated with the following equation: AT=HR((S+B), wherein, AT is the increment, HR is the determined amount of the heat energy, S is the calculated value of the heat capacity of the engine body and B is the value of the heat capacity of the coolant.

According to an embodiment the apparatus may comprise means for operating a thermal management strategy of the cooling system on the basis of the determined value of the coolant temperature, by way of an example the means for operating the thermal management strategy may comprise means for regulating a speed at which the coolant pump operates on the basis of the determined value of the coolant temperature.

According to a further embodiment, wherein the cooling system comprises a coolant temperature sensor, the apparatus may comprise: -means for measuring a value of the coolant temperature by means of a coolant temperature sensor; -means for calculating a difference between the determined value of the coolant temperature and the measured value of the coolant temperature; and -means for identifying a malfunctioning of the coolant temperature sensor, if the calculated difference gets equal to or greater than a predetermined threshold value thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The various embodiments will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows an automotive system; Figure 2 is a cross-section of an internal combustion engine belonging to the automotive systemoffigurel; Figure 3 is a schematic view of a cooling system according to an embodiment of the present solution; Figure 4 is a flowchart of a method of determining a coolant temperature in the cooling system of Figure 3, according to an embodiment of the invention.

Figure 5 is a flowchart of a method of determining a coolant temperature in the cooling system of Figure 3, according to a further embodiment of the invention.

Figure 6 is a flowchart of a method of determining a coolant temperature in the cooling system of Figure 3, according to another embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Some embodiments may include an automotive system 100, as shown in Figures 1-3, that includes an intemal combustion engine (ICE) 110 having an engine body 115 which comprises a cylinder block 120 defining at least one cylinder 125 having a piston 140 coupled to rotate a crankshaft 145. The engine body 115 comprises also a cylinder head 130 which cooperates with the piston 140 to define a combustion chamber 150.

A fuel and air mixture (not shown) is disposed in the combustion chamber 150 and ignited, resulting in hot expanding exhaust gasses causing 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 160 from a fuel rail 170 in fluid communication with a high pressure fuel pump 180 that increase 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 time with the crankshaft 145. The valves 215 selectively allow air into the combustion chamber 150 from the intake port 210 and alternately allow exhaust gases to exit through an 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 duct 205 may provide air from the ambient environment to the intake manifold 200. In other embodiments, a throttle valve 330 may be provided to regulate the S flow of air into the intake 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 air intake duct 205 and intake manifold 200. An intercooler 260 disposed in the air intake duct 205 may reduce the temperature of the air.

The turbine 250 rotates 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. The exhaust gases exit the turbine 250 and are directed into an exhaust gas aftertreatment system 270. This example shows a variable geometry turbine (VGT) 250 with a VGT actuator 290 arranged to move the vanes to alter the flow of the exhaust gases through the turbine 250.

The exhaust gas aftertreatment system 270 may include an exhaust pipe 275 having one or more exhaust aftertreatment devices 280. The aftertreatment devices 280 may be any device configured to change the composition of the exhaust gases. Some examples of aftertreatment devices 280 include1 but are not limited to, catalytic converters (two and three way), oxidation catalysts, lean NOx traps, hydrocarbon adsorbers, selective catalytic reduction (8CR) systems, and particulate filters. Other embodiments may include an exhaust gas recirculation (EGR) system 300 coupled between the exhaust manifold 225 and the intake 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.

The automotive system 100 may further include an electronic control unit (ECU) 450 in communication with one or more sensors and/or devices associated with the ICE 110.

The ECU 450 may receive input signals from various sensors configured to generate the signals in proportion to various physical parameters associated with the ICE 110. The sensors include, but are not limited to, a mass airflow, pressure, temperature sensor 340, a manifold pressure and temperature sensor 350, a combustion pressure sensor 360, coolant and oil temperature and level sensors 380, a fuel rail pressure sensor 400. a cam position sensor 410, a crank position sensor 420, exhaust pressure and temperature sensors 430, an EGR temperature sensor 440, and an accelerator pedal position sensor 445.

Furthermore, the ECU 450 may generate output signals to various control devices that are arranged to control the operation of the ICE 110, including, but not limited to, the fuel injector 160, the throttle valve 330, the EGR Valve 320, the VGT actuator 290, and the cam phaser 155. Note, dashed lines are used to indicate communication between the is ECU 450 and the various sensors and devices, but some are omitted for clarity.

Turning now to the ECU 450, this apparatus may include a digital central processing unit (CPU 460) in communication with a memory system and an interface bus. The CPU is configured to execute instructions stored as a program in the memory system, and send and receive signals to/from the interface bus. The memory system may include various storage types including optical storage, magnetic storage, solid state storage, and other non-volatile memory. The interface bus may be configured to send, receive, and modulate analog and/or digital signals to/from the various sensors and control devices.

The program may embody the methods disclosed herein, allowing the CPU to carryout out the steps of such methods and control the ICE 110.

The program stored in the memory system is transmitted from outside via a cable or in a wireless fashion. Outside the automotive system 100 it is normally visible as a computer program product, which is also called computer readable medium or machine readable medium in the art, and which should be understood to be a computer program code residing on a carrier, said carrier being transitory or non-transitory in nature with the consequence that the computer program product can be regarded to be transitory or non-transitory in nature.

An example of a transitory computer program product is a signal, e.g. an electromagnetic signal such as an optical signal, which is a transitory carrier for the computer program code. Carrying such computer program code can be achieved by modulating the signal by a conventional modulated technique such as QPSK for digital data, such that binary data representing said computer program code is impressed on the transitory electromagnetic signal. Such signals are e.g. made use of when transmitting computer program code in a wireless fashion via a WiFi connection to a laptop.

In case of a non-transitory computer program product the computer program code is is embodied in a tangible storage medium. The storage medium is then the non-transitory carrier mentioned above, such that the computer program code is permanently or non-permanently stored in a retrievable way in or on this storage medium. The storage medium can be of conventional type known in computer technology such as a flash memory, an Asic, a CD or the like.

Instead of an ECU 450, the automotive system 100 may have a different type of processor to provide the electronic logic, e.g. an embedded controller, an onboard computer, or any processing module that might be deployed in the vehicle.

The ICE 110 further comprises a cooling system 500 having a coolant circuit 505, schematically depicted in figure 3, that connects the ICE 110, a radiator 510, a thermostat 515 and a coolant pump 520. A bypass conduit 525 directly connects a portion of the coolant conduit 505 placed upstream of the radiator 510 to the thermostat 515 and bypasses the radiator 510, thus defining a "short-circuit" which connects the ICE 110, the thermostat 515 and the coolant pump 520. The coolant circuit 505, in order to pass through the ICE 110, comprises a cooling jacket 530 comprising a cylinder head cooling jacket, a cylinder block cooling jacket. The coolant which runs into the coolant circuit 505 is generally a mixture of water and glycol.

The thermostat 515 is realized as a three way valve actuated by the coolant temperature and, when is closed, in orderto speed up the warm-up of the ICE 110, allows the coolant to divert back to ICE 110 via the bypass conduit 525, and hence it prevents the coolant from flowing through the radiator 510 till the coolant temperature reaches a selected target temperature.

Therefore, during cold start and warm-up operating modes of the ICE 110 the thermostat 515 remains closed and the coolant pump 520 circulates the coolant only along the "short circuit, i.e. along the cooling jacket 530, the bypass conduit 525 and the thermostat 515. When the coolant temperature rises up to the target temperature the thermostat 515 opens and the coolant pump 520 circulates the coolant along the entire coolant conduit 505. The coolant circuit 505 may also comprise one or more flow control valves operated by the ECU 450 in order to modify the path of the coolant along the coolant circuit 505.

The coolant pump 520 may be one of an electrical, mechanical, and hybrid electrical-mechanical coolant pump 520. The mechanical pump variation may be powered by the crankshaft 145 and the electrical or hybrid pump may be controlled by the ECU 450, and may provide coolant independent of engine speed and allow for stopping or slowing down coolant flow, for maximum engine andlor coolant warm-up.

The cylinder block 120 may be made of a first material, for example of cast iron, or of a plurality of first materials, for example of Aluminum or Aluminum alloy including one or more reinforcing inserts made of a heavier and stiffer material, for example a ferrous material such as cast iron or steel.

A value mbIock of the overall mass of each first materials of which is made the cylinder block 120 is stored in the memory system, for example each of the values mblock of the overall mass may be a value pre-estimated via CAD design and stored in the memory system.

Moreover, a value Cp,bloclc of the specific heat of each first materials of which is made the cylinder block 120 is stored in the memory system, for example each of the values cp.b of the specific heat may be a value known from literature and stored in the memory system.

Again, the cylinder head 130 may made of a second material, for example of cast iron or Aluminum.

A value mh.s of the overall mass of the second material of which is made the cylinder head 120 is stored in the memory system, for example the value mhd of the overall mass of the cylinder head 130 may be pre-estimated via CAD design and stored in the memory system.

Moreover, a value Cphoad of the specific heat of the second material of which is made the cylinder head 130 is stored in the memory system, for example the value cp.head of the specific heat may be a value known from literature and stored in the memory system.

Moreover, a value ccoia,,t of the specific heat of the coolant, generally a mixture of water and glycol, may be stored in the memory system, for example the value cp,iaM of the specific heat may be a value known from literature and stored in the memory system.

A value mant of the mass of the coolant which circulates (only) in the "short circuit" may be stored in the memory system, for example the value mccoia,,t of the inner volume of the "short circuit" may be pre-estimated via CAD design and stored in the memory system.

A value of an heat capacity B of the coolant may be calculated from the value of and the value according to the formula * miam = B; for example the value B of the heat capacity of the coolant may be calculated (for example by the ECU 450) or may be a value known from literature, in any case, the value B may be stored in the memory system.

One of the tasks of the ECU 450 may be that of determining the temperature of the coolant by way of an estimation thereof during the warm-up of the ICE 110 and therefore when the thermostat 515 is closed, wherein the coolant temperature increases, warmed by the ICE 110, up to the target temperature.

As a mailer of fact, after a cold start of ICE 110 and during the warm-up thereof, the temperature of the coolant gradually uses from a starting temperature To up to the target temperature; the starting temperature To is for example equal to the temperature of the external environment, i.e. To = Tamb, wherein Tomb, is the ambient temperature, which may be measured by the temperature sensor 340 and stored in the memory system.

As soon as the ICE 110 is started (for example after a cold start thereof), the ECU 450 may be configured to cyclically repeat a control cycle represented in figure 4.

Each control cycle (i) provides for the ECU 450 to determine (block 81) an amount of heat energy HR1 (so called heat rejection), which is transferred from the hot expanding exhaust gasses in the combustion chamber 150 to the engine body 115 and to the coolant through the cooling jacket 530, on the basis of an engine operating point value, i.e. an engine speed and an engine torque of the ICE 110.

In particular, as the amount of heat energy HR transferred from the hot expanding exhaust gasses in the combustion chamber 150 to the engine body 115 and to the coolant may depend on the engine operating points, namely on the engine speed and on the engine torque, the ECU 450 may be configured to determine the current values of the engine speed Wi and of the engine torque L and to use them to determine a corresponding current amount of heat energy HR1.

By way of example, the current amount of heat energy HR1 may be provided as an output of a pre-calibrated map which receives as an input said current values wj,L1. This map may be pre-determined during experimental activities performed on a test bench and stored in the memory system.

The control cycle (i) provides for the ECU 450 to calculate (block S2) an increment AT of a temperature of the coolant during warm-up on the basis of the determined current amount of heat energy HR1.

In particular, the increment AT is the difference between the temperature Ti of the coolant at the current control cycle i and the determined temperature Li of the coolant at the previous control cycle i-i, therefore AT = Ti -Li.

For example, at the control cycle number 1, with the assumption that the ECU 450, after the cold start of ICE 110, immediately starts to perform the first control cycle (i=l), the temperature Li of the coolant at the previous control cycle i-I =0 is a known value of temperature, for example the ambient temperature, i.e. Li = To = Tamb.

To calculate the increment AT, the control cycle (i) provides for the ECU 450 to calculate (block 83) a current value Si of an heat capacity of the engine body 115.

In particular, the current value S1 of the heat capacity is the product of a maximum value A of the heat capacity of the engine body 115 and a current correction factor k1, S1 = kiA.

The maximum value A of the heat capacity is determined on the basis of the values mb and mh of a mass of the engine body 115, namely of the cylinder block 120 and of the cylinder head 130, and the respective specific heat values cpbrodc and cph..

In particular, the maximum value A of the heat capacity may be calculated as the sum of any heat capacities A', A' of any materials of which is made the engine body 115, wherein each of the heat capacities A', A" is the product of the mass value mblock, mMad of the material of which the engine body 115 is made with the respective value Cp,head of the specific heat of the same material.

In an example, in which the cylinder head 130 is made of the second material and the cylinder block 120 is made of only one of the first materials, the maximum value A of the heat capacity (an equivalent heat capacity) is calculated with the following formula: A = (A' + A") = (mb * cpblock + mhd * wherein A is the heat capacity of the cylinder block 120 and A' is the heat capacity of the cylinder head 120.

According to an embodiment, the control cycle (i) provides for the ECU 450 to calculate (block S5) the current correction factor K according to the following formula: k1 = 0.0629 * e (O.0557T1-1), wherein k1 is the correction factor and Li is the determined coolant temperature (in is Celsius degrees) at the previous control cycle (i-i).

In particular, the control cycle (i) provides for the ECU 450 to compare (block S6) the determined coolant temperature Li at the previous control cycle (i-i) with a determined threshold value Tth thereof, for example said temperature threshold value Ith may be equal to 50 °C and may be predetermined during experimental activities performed on a test bench and stored in the memory system.

The control cycle (i) provides for the ECU 450 to calculate (block S5) the correction factor ki according the above formula only if the determined coolant temperature Li at the previous control cycle (i-I) is smaller than the determined threshold value Im, otherwise the control cycle provides for the ECU 450 to set (block S7) the correction factorkiasequalto 1.

According to an embodiment, the calculated current value Si=kiA of the heat capacity of engine body 115 and the value B of the heat capacity of the coolant may be used, together with the current amount of heat energy HR1, for calculating (block S2) the increment AT of the coolant temperature.

In particular, the increment AT may be calculated by the ECU 450 with the following equation: AT = Ti -Li. = HR1 / (Si+ B), wherein, AT is the increment, HR1 is the determined current amount of heat energy, Si = = ki(A' + A") is the current value of the heat capacity of the engine body 115 and B is the heat capacity of the coolant.

In particular, being the starting temperature a known value (namely the ambient temperature Tamb) the only unknown value of the above equation is the current value Ti of the coolant temperature which may be therefore univocally determined by means of said equation.

As a matter of fact, the control cycle (i) provides for the ECU 450 to determine (block S4) the current temperature T as the sum of the coolant temperature of the previous control cycle T11 and the calculated increment AT, namely TiTi + AT = Th + HR1 / (S + B).

At every control cycle (i) the determined coolant temperature Ti may be used by the ECU 450 for operating thermal management strategies of the cooling system 500, during the warm-up operating mode of the ICE 110, or for testing purposes, as hereinafter disclosed.

According to an embodiment shown in Figure 5, the determined temperature Ti may be used by the ECU 450 to control (block SB) one or more thermal management actuators of the cooling system 500.

By way of an example, the ECU 450 may operate the coolant pump 520 to regulate the speed at which the coolant pump 520 operates on the basis of the determined coolant temperature T1.

As an example, the ECU 450 may be configured to determine a temperature increment rate and a threshold value thereof, predetermined during experimental activities performed on a test bench and stored in the memory system; again the ECU 450 may be configured to slow down the speed at which the coolant pump 520 operates lithe determined temperature increment rate is smaller than the determined threshold value.

The ECU 450 may further be configured to regulate the operation of one or more of the flow control valves and/or the thermostat 515 of the cooling system 500, on the basis of the determined temperature Ti, in such a way to modify the path of the coolant along the coolant circuit 505.

According to a further embodiment shown in Figure 6, one of the tasks of the ECU 450 may be that of executing a test strategy aimed to identify whether a coolant temperature sensor 535, which may be present on the coolant circuit 505 (as depicted with a dashed line in figure 3), is properly functioning.

To do so, the ECU 450 may be configured to perform (block S9) a test strategy of the proper functioning of the coolant temperature sensor 535.

By way of an example, the test strategy may provide for the ECU 450 to perform the steps of: -measuring (block SlO) a coolant temperature Tmea$ud, for example by means of the coolant temperature sensor 535; -calculating (block 511) a difference between the determined coolant temperature Tr and the measured coolant temperature and -identifying (block S12) a malfunctioning of the coolant temperature sensor 535, if the calculated difference gets equal to or greater than a predetermined threshold value thereof, wherein this predetermined threshold value may be predetermined during experimental activities performed on a test bench and stored in the memory system.

In practice, a malfunctioning of the coolant temperature sensor 535 may be identified if the measured coolant temperature Tmeam is too much different from the determined coolant temperature Ti.

On the contrarç the ECU 450 identifies that the coolant temperature sensor 535 is functioning properly if the calculated difference is smaller than the predetermined threshold value.

Once a malfunctioning of the coolant temperature sensor 535 has been identified, the ECU 450 may be configured to perform one or more recovery actions. These recovery actions may include, but are not limited to, the generation (block 812) of a signal perceivable by a driver, for example through the activation of a signaller (e.g. a light and/or a sound) disposed in a dashboard of the automotive system 100. In this way the driver may be informed of the malfunctioning of the coolant temperature sensor 535 and suggested to take some countermeasures, for example to go to the nearest car service center, by way of an example in order to substitute the coolant temperature sensor 535.

At the same time, other tasks of the ECU 450 may be that of executing other test strategies aimed to identify whether a component of the cooling system 500 is properly functioning, for example if the coolant pump 520 is properly functioning and/or if no coolant leakages from the conduits of the usholl circuit" are occurring.

To do so, by way of an example, each of these test strategies may provide for the ECU 450 to perform the steps of: -measuring a coolant temperature Imeasu for example by means of the coolant temperature sensor 535; -identifying that the coolant pump 520 does not properly functions andlor a coolant leakage from the conduits of the "short circuit", if the determined coolant temperature Ii differs from the measured coolant temperature of a quantity equal to or greater than a predetermined threshold value thereof, wherein this predetermined threshold value may be predetermined during experimental activities performed on a test bench S and stored in the memory system.

In practice, a malfunctioning of the coolant pump 520 and/or a coolant leakage from the conduits of the "short circuit" may be identified if the measured coolant temperature Tmoasur,o is too much different from the expected determined coolant temperature Ti.

Also in this case once a malfunctioning of the coolant system 100 has been identified, the ECU 450 may be configured to perform one or more of above disclosed recovery actions.

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 examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description 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 arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents.

REFERENCE NUMBERS

100 automotive system internal combustion engine engine body cylinder 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 duct 210 intake port 215 valves 220 exhaust port 225 exhaust manifold 230 turbocharger 240 compressor 250 turbine 260 intercooler s 270 exhaust gas aftertreatment system 275 exhaust gas line 280 aftertreatment devices 290 VGT actuator 300 exhaust gas recirculation duct 310 EGR cooler 320 EGR valve 330 throttle valve 340 mass airflow, pressure, temperature sensor 350 manifold pressure and temperature sensor 360 combustion pressure sensor 380 coolant temperature and level seisors 385 lubricating oil temperature and level sensor 400 fuel rail digital pressure sensor 410 cam position sensor 420 crank position sensor 430 exhaust pressure and temperature sensors 440 EGR temperature sensor 445 accelerator pedal position sensor 450 ECU/controller 460 central processing unit 500 cooling system 505 coolant circuit 510 radiator 515 thermostat 520 coolant pump 525 bypass conduit 530 cooling jacket 535 coolant temperature sensor S1-S12 blocks

Claims

CLAIMS1. A method of controlling a cooling system (500) of an internal combustion engine (110), wherein the cooling system (500) comprises a coolant pump (520), a cooling jacket (530) passing through an engine body (115) and receiving a coolant from the coolant pump (520), wherein the method comprises the steps of: -determining an amount of heat energy transferred from the engine body (115) to the coolant through the cooling jacket (530) on the basis of an engine speed and an engine torque of the intemal combustion engine (110); -calculating an increment of a temperature of the coolant as a function of the determined amount of the heat energy; and -determining a value of the coolant temperature on the basis of the calculated increment.
2. The method according to claim 1, comprising the steps of: -calculating a value of an heat capacity of the engine body (115); -using the calculated value of the heat capacity and a value of an heat capacity of the coolant for calculating the increment.
3. The method according to claim 2, comprising the steps of: -calculating a maximum value of the heat capacity of the engine body (115) on the basis of a value of a mass of the engine body (115) and a value of a specific heat of a material of which the mass of the engine body (115) is made; -determining a correction factor on the basis of the determined value of the coolant temperature; and -calculating the value of the heat capacity as a function of the maximum value and the correction factor.
4. The method according to claim 3, wherein the correction factor is calculated with the following formula: k = 0.0629 * e (thO557T) wherein k is the correction factor and T is determined value of the coolant temperature, if the determined value of the coolant temperature is smaller than a determined threshold value thereof.
5. The method according to claim 3, wherein the correction factor is set as equal to 1, ii the determined value of the coolant temperature gets equal to or larger than a determined threshold value thereof.
6. The method according to any of the preceding claims from 3 to 4, wherein the increment is calculated with the following equation: AT=HR/(S+B), wherein, aT is the increment, HR is the determined amount of the heat energy, S is the calculated value of the heat capacity of the engine body (115) and B is the value of the heat capacity of the coolant.
7. The method according to any of the preceding claims, comprising the step of operating a thermal management strategy of the cooling system (500) on the basis 2 C of the determined value of the coolant temperature.
8. The method according to claim 7, wherein the thermal management strategy comprises the step of regulating a speed at which the coolant pump (520) operates on the basis of the determined value of the coolant temperature.
9. The method according to any of the preceding claims, comprising the steps of: -measuring a value of the coolant temperature by means of a coolant temperature sensor (535); -calculating a difference between the determined value of the coolant temperature and the measured value of the coolant temperature; and -identifying a malfunctioning of the coolant temperature sensor (535), if the calculated difference gets equal to or greater than a predetermined threshold value thereof.
1O.A computer program comprising a computer-code for performing, when run on a computer, the method of any of the preceding claims.
Ii.Acomputer program product comprising a carrier on which the computer program of claim 10 is stored.
12.A control apparatus for an internal combustion engine (110), comprising an electronic control unit (450), a data carrier associated to the electronic control unit (450) and the computer program of claim 10 stored in the data carrier.
13. An internal combustion engine (110) equipped with a cooling system (500) comprising a coolant pump (520), a cooling jacket (530) passing through an engine body (115) of the internal combustion engine (110) and receiving a coolant from the coolant pump (530), and an electronic control unit (450) configured for carrying out the method according to any of the claims from I to 9.