Coolant fluid leakage detection method for a cooling system of an internal combustion engine of a motor vehicle

Abstract

Coolant fluid leakage detection method for a cooling system of an internal combustion engine (5) of a motor vehicle comprising measuring (10, 20) the temperature at two different instants (Tti,Tti+1) and comparing (30) measurements taken. If the difference is smaller than a first threshold value (X1) restart measuring stages and if it is equal or bigger then measuring (40) the knocking level (K) of the internal combustion engine. If knocking level (K) is lower than a second threshold value (X2), then set a counter (Ct) to zero and restart measuring stages. Conversely if knocking level (K) is equal or bigger, then add one unit to the counter. If the resulting counter value is lower than a third threshold value (X3), then restart measuring stages and if the counter value is equal to the third threshold value (X3), then send (60) a leakage alert.

Description

[0001] Coolant fluid leakage detection method for a cooling system of an internal combustion engine of a motor vehicle

[0002] DESCRIPTION

[0003] Technical field

[0004] The present invention belongs to the automotive technical field, and more particularly to the area to the area of cooling systems for motor vehicles, such as, for example and without being limitative, cars, vans, trucks and buses.

[0005] Thus, a first object of this invention is a coolant fluid leakage detection method, which is capable of detecting coolant fluid leakages in the cooling system of an internal combustion engine of a motor vehicle, without the cooling circuit necessarily having to be provided with a water level / presence detector for this specific purpose.

[0006] The present invention also refers to a cooling system for an internal combustion engine of a motor vehicle which allows to implement said coolant fluid leakage detection method.

[0007] Background of the invention

[0008] Under certain circumstances, for example extreme environmental conditions, or as a consequence of prolonged used, the cooling system of a motor vehicle may be damaged, resulting in a significative coolant fluid leak, usually water.

[0009] As a result of coolant leakage, different parts of engine, such as the crankcase and / or cylinder heads, could be no longer cooled correctly. In that case the high rise in temperature due to the combustion inside the engine cylinders can rapidly damage the engine and cause serious damage to it, including an eventual breakdown.

[0010] In those cases, in which the cooling circuit includes a water level / presence detector, in particular in a coolant reservoir, it is known in the state of the art to send an alert to the vehicle's dashboard, for example within three seconds, so as to warn the driver that there is a risk of engine failure, so that he or she stops the vehicle.

[0011] Such an alert concerning the appearance of a fault is also possible in those cases in which an electric water pump is present then, a so-called "dry run" function operates in a similar way. As is well known, an electric water pump operates with a certain amount of current in order to deliver a normal flow of coolant to the engine. In the event of a coolant leakage, water isintroduced into the circuit and a two-phase mixture of water and air impinges on the pump blades, reducing the current required to drive the flow. A leakage is diagnosed by comparing the current with a predefined threshold.

[0012] However, if the engine is fitted with a mechanical water pump, driven by the engine, or more precisely by the engine crankshaft, existing cooling systems are unable to employ a "dry run" detection strategy.

[0013] If those cases in which the engine is associated with a diagnosis of the cooling system, it is possible to alert the driver of the risk of engine failure and invite him (or her) to stop the vehicle very quickly. Nevertheless, based on the observation that some customers do not follow this recommendation and stop the engine, there is also a need to develop a cooling system which, in the event of coolant leakage diagnosis, it is capable limiting the consequences of said leakage. To that end, an invention developed by Nissan is known to firstly clean up the engine's performance (more or less sharp reduction in torque / power), which delays the appearance of damage to the engine, and then, in a second phase, to cause successive stops and restarts of fuel injection, which has the effect of creating unpleasant vehicle behavior: the driver finds himself shaken and ends up stopping the vehicle.

[0014] However, if the cooling circuit is not fitted with a coolant fluid (usually water) level / presence sensor or if such a sensor fails, and if it is not fitted with an electric water pump enabling a "dry run" function, particularly if the engine has a mechanical water pump, it is not possible to diagnose a leak.

[0015] Document CN115452255 discloses a vehicle coolant leakage prediction method and device which employs a deep learning neural network model, directed to the detection of coolant leakage at an early stage. Nevertheless, for cost reasons, it would be preferable to develop new coolant leakage detection methods, which do not involve major modifications to the vehicle, and which are easy and economical to implement.

[0016] Summary of the invention

[0017] With the aim of providing a solution to the abovementioned problems, a first object of the present invention refers to a coolant fluid leakage detection method for a cooling system of an internal combustion engine of a motor vehicle, the cooling system comprising:

[0018] a first cooling circuit having a closed loop shape and surrounding the internal combustion engine; anda pump, arranged for circulating a coolant fluid through the first cooling circuit and a second cooling circuit;

[0019] a second cooling circuit, connected to a radiator and being also connected both to the first cooling circuit and the pump;

[0020] a temperature sensor interposed between the first cooling circuit and the second cooling circuit, the temperature sensor being configured to allow the passage of coolant fluid to the second circuit only if the temperature detected in the first circuit interior exceeds a predefined threshold;

[0021] the fluid leakage detection method being characterized in that it comprises the following sequential stages:

[0022] a) with the internal combustion engine of the motor vehicle running, measure the temperature with the temperature sensor at a first instant;

[0023] b) wait for a predetermined period of time and measure again the temperature with the temperature sensor at a second instant;

[0024] c) compare the temperature measured at the second instant with temperature measured at the first instant, if the temperature difference is lower than a predefined first threshold value, then go back to previous measuring stage a), conversely if the temperature difference is equal to or bigger than the first predefined threshold value, then measure the knocking level of the internal combustion engine and compare it with a second predefined threshold value;

[0025] d) if the knocking level of the internal combustion engine is lower than the second predefined threshold value, then set a counter to zero and go back to previous measuring stage a), conversely if the knocking level of the internal combustion engine is equal to or bigger than the predefined second threshold value, then add one unit to the counter;

[0026] e) compare the value of the counter with a third predefined threshold value, if the value of the counter is lower than a third predefined threshold value then go back to previous measuring stage a), and conversely if the value of the counter of the internal combustion engine is equal to the third predefined threshold value, then send a coolant fluid leakage alert.

[0027] The abovementioned fluid leakage detection method according to the present invention, can operate correctly even though the cooling circuit of the internal combustion engine of the motor vehicle is not equipped with a coolant level / presence sensor, or even if that sensor fails.In fact, the detection method of the invention exploits the presence of a coolant temperature sensor present which is present in the cooling circuit. Said temperature sensor is present regardless of the type of pump (electric or mechanical) employed by the cooling circuit and can therefore be used advantageously for diagnostics when the engine has a mechanical pump, i.e. without the "dry run" function required by prior art to enable the coolant leakage to be diagnosed.

[0028] Thus, in the method according to the present invention when a significant leakage of coolant fluid occurs, the temperature sensor perceives a falling temperature when the coolant fluid level decreases. Consequently, the temperature sensor will perceive the ambient temperature instead of detecting a temperature in the range of 120°C because it is no longer in contact with the coolant fluid (which in a preferred embodiment of the invention is water) but rather with air.

[0029] On the other hand, the lack of cooling fluid, for example water, causes an increase in the temperature of the cylinder head, which in turn causes an increase in the level of knocking detected by the sensor(s) adapted to this function (knock sensors). In this case, the detection method according to the present invention sends a coolant fluid leakage alert to warn the driver of the risk to the engine.

[0030] The temperature sensor can be optionally provided with a thermostat. The temperature sensor can also be housed for example, but not restrictively, inside a water outlet. Nevertheless, the present invention also contemplates the possibility of the temperature sensor temperature sensor being housed inside a water inlet.

[0031] In a preferred embodiment, the coolant fluid leakage detection method according to the present invention, after the stage of sending the coolant fluid leakage alert also comprises the following additional stage:

[0032] f) sending instructions to an on-board computer of the motor vehicle for reducing the speed of the motor vehicle to a predefined value.

[0033] Said predefined value can be, for example, and without being limitative, 30 km / h.

[0034] A second object of the present invention refers to a computer readable storage medium comprising instructions which, when executed in a computer, cause the computer to carry out any of the abovementioned coolant fluid leakage detection methods for a cooling system of an internal combustion engine of a motor vehicle, according to the first object of the invention.In the context of the present invention, a computer is to be understood as any device that includes processing circuitry and a memory coupled to the processing circuitry, such that instructions can be stored in the memory and those instructions being also executable by the processing circuitry. Therefore, the term computer expressly includes, among other devices: on-board computers of motor vehicles, on-board diagnostic systems of motor vehicles, laptop computers, tablets, smartphones and smartwatches.

[0035] A third object of the present invention is a computer product comprising instructions which, when executed in a computer, cause the computer to carry out any of the abovementioned coolant fluid leakage detection methods for a cooling system of an internal combustion engine of a motor vehicle, according to the first object of the invention.

[0036] A fourth object of the present invention is an on-board computer of a motor vehicle comprising processing circuitry and a memory coupled to the processing circuitry, the memory storing instructions which, when executed by the processing circuitry, cause the processing circuitry to carry out any of the abovementioned coolant fluid leakage detection methods for a cooling system of an internal combustion engine of a motor vehicle, according to the first object of the invention.

[0037] A fifth object of the present invention is an on-board diagnostic system of a motor vehicle comprising processing circuitry and a memory coupled to the processing circuitry, the memory storing instructions which, when executed by the processing circuitry, cause the processing circuitry to carry out any of the abovementioned coolant fluid leakage detection methods for a cooling system of an internal combustion engine of a motor vehicle, according to the first object of the invention.

[0038] Brief description of the drawings

[0039] As a means for better understanding at least one embodiment of the present invention, the following set of drawings is introduced by way of schematic illustration and in a non-limitative manner.

[0040] Figure 1A: is a schematic diagram showing the operation of a prior art cooling circuit of an internal combustion engine, when said engine is cold;

[0041] Figure 1 B: is a schematic diagram showing the operation the cooling circuit of Fig. 1A once said engine has been warmed up; andFigure 2: is a flow chart that schematically illustrates one possible embodiment of a coolant fluid leakage detection method, according to the present invention.

[0042] Detailed description of the invention

[0043] Equal or similar elements will be designated with the same numerical references throughout the figures.

[0044] Figures 1 A and 1 B schematically show the operation of a prior art cooling circuit, intended for cooling an internal combustion engine 5 of a motor vehicle, when said engine is still cold (Fig.

[0045] 1A) and after said engine has acquired has become hot enough to trigger the full cooling system (Fig. 1 B).

[0046] As can be seen in the figures, the cooling circuit comprises a first cooling circuit 1 , which has a closed loop shape and surrounds the internal combustion engine 5.

[0047] A pump 3 is also provided. Pump 3, which may be driven by the engine crankshaft or be of the electric type is arranged for circulating a coolant fluid, in this case water, both through the first cooling circuit 1 and through a second cooling circuit 2.

[0048] The second cooling circuit 2, is bigger in size than the first cooling circuit. In fact, in this particular embodiment it comprises two different branches, both of them connected to a radiator 4.

[0049] Radiator 4 is generally located at the front of the vehicle, and once in operation, is used to remove heat from the air and, if necessary, to cool the coolant fluid by using the air it receives. In this case, radiator 4 is associated with a thermocontact and a motorized fan, which is used to supply air to the radiator when 4 it receives little or insufficient air. The motorized fan is activated in response to the thermocontact, with a thermostatic sensor located in the radiator 4 measuring the temperature of the water at that point. If the temperature is too high, the fan unit is activated.

[0050] In addition, one of the branches of the second cooling circuit 2 is connected to an expansion tank 6 intended to hold the water, which acts as coolant fluid. The tank can be option ally provided with a conventional minimum and maximum system sensor to measure the level and / or absence of liquid. Depending on the flow rate and temperature within the cooling circuit, liquid can be added. It should be noted that the leakage detection method of the invention canbe applied, but not exclusively, in the case where the circuit does not include such a sensor intended to measure the level and / or absence of liquid in the expansion tank 6.

[0051] The coolant circuit also comprises temperature sensor 7 interposed between the first cooling circuit 1 and the second cooling circuit 2. The temperature sensor 7 is associated with a fluid passage valve, so that said valve only allows the passage of coolant fluid to the second circuit 2 if the temperature detected by temperature sensor 7 in the interior of the first circuit 1 exceeds a predefined threshold.

[0052] As a result, when the engine is not sufficiently warm (as shown in Figure 1A), the water circulating through the first cooling circuit 1 which is contact with the internal combustion engine 5 does not have temperature enough to reach the predefined temperature threshold. Consequently, the temperature sensor 7 will not open the valve and the water will only be able to circulate through the first cooling circuit 1 . On the contrary, once the internal combustion engine 5 has become hot enough, the temperature of the water circulating through the first cooling circuit 1 will enough for exceeding the predefined temperature threshold, which will cause the valve linked with the temperature sensor 7 to open, allowing passage of water to the second refrigeration circuit 2.

[0053] Figure 2: shows a flow chart of one possible embodiment of a coolant fluid leakage detection method according to the present invention, for a cooling system of an internal combustion engine 5 of a motor vehicle. In this case, the method is implemented with the aid of a computer, for example and without being limitative, an on-board computer of a motor vehicle, an on-board diagnostic system of a motor vehicle, a laptop computer, a tablet, a smartphone or a smartwatch.

[0054] On the other hand, the cooling system of the internal combustion engine 5 of a motor vehicle is similar to the one illustrated in Fig. 1 A and 1 B (so it is not illustrated in another figure) and comprises a first cooling circuit 1, with closed loop shape and which surrounds the internal combustion engine 5. It also comprises a second cooling circuit 2, connected to a radiator 4, to the first cooling circuit 1 and to a pump 3. arranged for circulating a coolant fluid through the first cooling circuit 1 and the second cooling circuit 2. A temperature sensor 7 is interposed between the first cooling circuit 1 and the second cooling circuit 2, the temperature sensor 7 being configured to allow the passage of coolant fluid to the second circuit 2 only if the temperature detected in the first circuit interior 1 exceeds a predefined thresholdThe detection method of Fig. 2 starts with step 10 in which, with the internal combustion engine 5 of the motor vehicle running, the temperature sensor 7 is used for measuring the temperature Tti at a first instant ti.

[0055] Then, in step 20, after waiting for a predetermined period of time the temperature sensor 7 is used again for measuring and temperature Tti+i at a second instant ti+i .

[0056] In step 30, the computer compares the temperature Tti+1 measured at the second instant ti+i with temperature Tti measured at the first instant ti. If the temperature difference Tti+1 - Tti is lower than a predefined first threshold value Xi, the method goes back to previous measuring stage 10. Conversely if the temperature difference Tti+1 - Tti is equal to or bigger than the first predefined threshold value Xi, step 40 is performed, wherein the knocking level K of the internal combustion engine 5 is measured with the aid of sensors and compared 40 with a second predefined threshold value X2.

[0057] If the knocking level K of the internal combustion engine is lower than the second predefined threshold value X2, then the computer sets a counter Ct to zero and goes back to previous measuring stage 10. Conversely if the knocking level K of the internal combustion engine is equal to or bigger than the predefined second threshold value X2, then one unit is added to the counter Ct.

[0058] In step 50 of the method shown in Fig. 2, the value of the counter Ct is compared with a third predefined threshold value X3. If the value of the counter Ct is lower than the third predefined threshold value X3, the method cgoes back to previous measuring stage 10. Conversely if the value of the counter Ct of the internal combustion engine is equal to the third predefined threshold value X3, then in the final step 60, a coolant fluid leakage alert is sent.

Claims

CLAIMS1. Coolant fluid leakage detection method for a cooling system of an internal combustion engine (5) of a motor vehicle, the cooling system comprising:- a first cooling circuit (1) having a closed loop shape and surrounding the internal combustion engine (5); and- a pump (3), arranged for circulating a coolant fluid through the first cooling circuit (1) and a second cooling circuit (2);- a second cooling circuit (2), connected to a radiator (4) and being also connected both to the first cooling circuit (1) and the pump (3);- a temperature sensor (7) interposed between the first cooling circuit (1 ) and the second cooling circuit (2), the temperature sensor (7) being configured to allow the passage of coolant fluid to the second circuit (2) only if the temperature detected in the first circuit interior (1) exceeds a predefined threshold;the detection method being characterized in that it comprises the following sequential stages:a) with the internal combustion engine (5) of the motor vehicle running, measure (10) the temperature (Tti) with the temperature sensor (7) at a first instant (ti);b) wait for a predetermined period of time and measure again (20) the temperature (Tti+i) with the temperature sensor (7) at a second instant (t+i);c) compare (30) the temperature (Tti+i) measured at the second instant (ti+i) with temperature (Tti) measured at the first instant (ti), if the temperature difference (Tti+i- Tti) is lower than a predefined first threshold value (Xi), then go back to previous measuring stage a), conversely if the temperature difference (Tti+i- Tti) is equal to or bigger than the first predefined threshold value (Xi), then measure (40) the knocking level (K) of the internal combustion engine (5) and compare (40) it with a second predefined threshold value (X2);d) if the knocking level (K) of the internal combustion engine is lower than the second predefined threshold value (X2), then set a counter (Ct) to zero and go back to previous measuring stage a), conversely if the knocking level (K) of the internalcombustion engine is equal to or bigger than the predefined second threshold value (X2), then add one unit to the counter (Ct);e) compare (50) the value of the counter (Ct) with a third predefined threshold value (Xs), if the value of the counter (Ct) is lower than the third predefined threshold value (X3), then go back to previous measuring stage a), and conversely if the value of the counter (Ct) of the internal combustion engine is equal to the third predefined threshold value (X3), then send (60) a coolant fluid leakage alert.

2. Method according to claim 1 , wherein the coolant fluid is water.

3. Method according to claim 2, wherein temperature sensor (7) comprises a thermostat and is housed inside a water outlet, or alternatively, is housed inside a water inlet.

4. Method according to any of claims 1 to 3, said method also comprising after the stage of sending the coolant fluid leakage alert, the following additional stage:f) sending instructions to an on-board computer of the motor vehicle for reducing the speed of the motor vehicle to a predefined value.

5. Computer readable storage medium comprising instructions, which when executed in a computer, cause the computer to carry out any of the coolant fluid leakage detection methods according to claims 1 to 4.

6. Computer product comprising instructions, which when executed in a computer, cause the computer to carry out any of the coolant fluid leakage detection methods according to claims 1 to 4.

7. On-board computer of a motor vehicle, comprising processing circuitry and a memory coupled to the processing circuitry, the memory storing instructions which, when executed by the processing circuitry, cause the processing circuitry to carry out any of the abovementioned coolant fluid leakage detection methods according to claims 1 to 4.

8. On-board diagnostic system of a motor vehicle, comprising processing circuitry and a memory coupled to the processing circuitry, the memory storing instructions which, when executed by the processing circuitry, cause the processing circuitry to carry out any of the abovementioned coolant fluid leakage detection methods according to claims 1 to 4.

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