METHOD OF CONTROLLING WATER INJECTION IN AN INTERNAL COMBUSTION ENGINE

Abstract

A method of controlling water injection in an internal combustion engine for a motor vehicle in case of freezing cold weather. The method includes: controlling the quality of the water, having a first sub-step of disapproving the quality of the water if the electrical conductivity σ of the water is not zero nor close to zero when the temperature T of the water is 0° C. or less and a second sub-step of approving the quality of the water if the electrical conductivity σ of the water is zero or close to zero when the temperature T of the water is higher than −4° C., preferably higher than −2° C. The method further includes a second sub-step of preventing water injection if the quality of the water is disapproved and a third step of allowing water injection if the quality of the water is approved.

Claims

1. A method of controlling water injection in an internal combustion engine for a motor vehicle, the method comprises the steps of: (a) determining a temperature T of the water contained in a water injection tank around a conductivity sensor, (b) controlling the quality of the water, which comprises the following step: (b10) disapproving the quality of the water if the electrical conductivity σ of the water is not zero nor close to zero, (c) preventing water injection if the quality of the water is disapproved, wherein step (b) is performed when the determined temperature T of the water is below 0° C.

2. The method according to claim 1, wherein the method further comprises the steps of: (b20) approving at step (b) the quality of the water if the electrical conductivity σ of the water is zero or close to zero when the determined temperature T of the water is higher than a predetermined threshold T.sub.min, (d) allowing water injection if the quality of the water is approved, wherein the value of the predetermined threshold T.sub.min is higher than 4° C., preferably higher than 2° C.

3. The method according to claim 2, wherein the water is heated when the determined temperature T is less than the predetermined threshold T.sub.min until the determined temperature T reaches at least the predetermined threshold T.sub.min.

4. The method according to claim 1, wherein the electrical conductivity σ of the water is close to zero when its value a is less than or equal to a predetermined threshold of electrical conductivity σ.sub.max, wherein the value of the predetermined threshold of electrical conductivity σ.sub.max is 30 μS/cm, more preferably 20 μS/cm, and most preferably 10 μS/cm.

5. A water injection system configured for implementing the method of controlling water injection in an internal combustion engine for a motor vehicle according to claim 1, the water injection system comprises: a water injection tank for storing the water, an electrical conductivity sensor for sensing the electrical conductivity σ of the water in the water injection tank, a temperature determining means for determining the temperature T of the water in the water injection tank around the conductivity sensor, a comparator for comparing the sensed electrical conductivity σ to the predetermined threshold of electrical conductivity σ.sub.max, a water injection pump for supplying water from the water injection tank to an injection line configured to be connected to the internal combustion engine, a first electronic control unit for approving or disapproving the quality of the water.

6. The water injection system according to claim 5, wherein the water injection system is configured for sensing the electrical conductivity σ of the water in the water injection tank when the determined temperature T is higher than a predetermined threshold T.sub.min, the predetermined threshold T.sub.min being higher than 4° C., preferably higher than 2° C.

7. The water injection system according to claim 6, wherein the water injection system further comprises a heater for heating the water stored in the water injection tank when the determined temperature T is less than the predetermined threshold T.sub.min until the determined temperature T reaches at least the predetermined threshold T.sub.min.

8. The water injection system according to claim 5, wherein the temperature determining means comprise a temperature sensor.

9. The water injection system according to claim 8, wherein the temperature sensor and the electrical conductivity sensor comprise each a sensing surface, and the distance between the sensing surface of the temperature sensor and the sensing surface of the electrical conductivity sensor is 30 mm or less.

10. The water injection system according to claim 8, wherein the temperature sensor and the electrical conductivity sensor are part of a quality sensor device.

11. The water injection system according to claim 5, wherein the water injection tank comprises a water delivery module.

12. The water injection system according to claim 11, wherein the water delivery module comprises the water injection pump, the temperature determining means, the electrical conductivity sensor and the heater.

13. An internal combustion engine system configured for implementing the method of controlling water injection in an internal combustion engine for a motor vehicle according to claim 1, the internal combustion engine system comprises an internal combustion engine, a water injection system including a water injection tank for storing the water, an electrical conductivity sensor for sensing the electrical conductivity σ of the water in the water injection tank, a temperature determining means for determining the temperature T of the water in the water injection tank around the conductivity sensor, a comparator for comparing the sensed electrical conductivity σ to the predetermined threshold of electrical conductivity σ.sub.max, a water injection pump for supplying water from the water injection tank to an injection line configured to be connected to the internal combustion engine, a first electronic control unit for approving or disapproving the quality of the water, and a second electronic control unit for allowing or preventing water injection by controlling the water injection pump.

14. A motor vehicle comprising an internal combustion engine system according to claim 13.

15. A non-transitory computer-readable medium comprising instructions of controlling water injection in an internal combustion engine for a motor vehicle, which, when executed by a processor, cause the processor to perform steps according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0049] FIG. 1 is a graph illustrating how the electrical conductivity of demineralized water change with temperature;

[0050] FIG. 2 is a graph illustrating how the electrical conductivity of non-demineralized water change with temperature;

[0051] FIG. 3 is a flow diagram of a method of controlling water injection in an internal combustion engine for a motor vehicle in case of freezing cold weather according to the invention;

[0052] FIG. 4 is a diagrammatic view of a water injection system and an internal combustion engine system according to the invention.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0053] The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn on scale for illustrative purposes. The dimensions and the relative dimensions do not correspond to actual reductions to practice of the invention.

[0054] It is to be noticed that the term “comprising”, used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression “a device comprising means A and B” should not be limited to devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B.

[0055] FIG. 1 is a graph of experimental data, wherein the x-axis represents the temperature T1 of demineralized water in ° C. (degree Celsius) and the y-axis represents the electrical conductivity σ1 of the demineralized water in μS/cm (microsiemens per centimeter). This graph has been constructed with actual values of σ1 as T1 gradually increases from −10° C. to 60° C. For this first set of experiments, a water tank is filled with 10 liters of a reference demineralized water. A reference demineralized water is a water having a conductivity of 150 μS/cm or less at room temperature, which is considered to be acceptable water for water injection in an internal combustion engine. The water tank comprises a temperature sensor for sensing T1, an electrical conductivity sensor for sensing σ1 and a heater for heating the demineralized water stored in the water tank. In an example, the electrical conductivity sensor senses at zero electrical frequency, i.e. it is a DC measurement. Alternatively, it may be an AC measurement. The heater is typically an electrical heater. The temperature sensor and the electrical conductivity sensor comprise each a sensing surface. In order to accurately measure the temperature of the demineralized water at the electrical conductivity sensor and properly associate a sensed electrical conductivity value to a corresponding sensed temperature value, the distance between the sensing surface of the temperature sensor and the sensing surface of the electrical conductivity sensor is 30 mm or less. The water tank is placed in a climatic chamber the time required to freeze the demineralized water. When the temperature of the demineralized water reaches −10° C. or less, the heater is activated to heat the demineralized water until T1 reaches at least 60° C.

[0056] During temperature increase, the applicant has found that σ1 is zero or close to zero when T1 increases from −10° C. to about 2° C., then σ1 increases with T1 when T1 increases from about 2° C. to 60° C.

[0057] FIG. 2 is a graph of experimental data similar to the graph of FIG. 1, wherein demineralized water is replaced with non-demineralized water. The x-axis represents the temperature T2 of non-demineralized water in ° C. and the y-axis represents the electrical conductivity σ2 of the non-demineralized water in μS/cm. This graph has been constructed with actual values of σ2 as T2 gradually increases from −10° C. to 66° C. For this second set of experiments, a water tank is filled with 10 liters of non-demineralized water. The water tank comprises a temperature sensor for sensing T2, an electrical conductivity sensor for sensing σ2 and a heater for heating the non-demineralized water stored in the water tank. The heater is typically an electrical heater. The temperature sensor and the electrical conductivity sensor comprise each a sensing surface. In order to accurately measure the temperature of the non-demineralized water at the electrical conductivity sensor and properly associate a sensed electrical conductivity value to a corresponding sensed temperature value, the distance between the sensing surface of the temperature sensor and the sensing surface of the electrical conductivity sensor is 30 mm or less. The water tank is placed in a climatic chamber the time required to freeze the non-demineralized water. When the temperature of the non-demineralized water reaches −10° C. or less, the heater is activated to heat the non-demineralized water until T2 reaches at least 60° C.

[0058] During temperature increase, the applicant has found that σ2 is zero or close to zero when T2 increases from −10° C. to about −4° C., then 62 increases with T2 when T2 increases from about −4° C. to 60° C.

[0059] By comparing the outputs of the first and second set of experiments, the applicant has found a reliable way to discriminate between demineralized and non-demineralized water. Indeed, if the electrical conductivity σ of a water is not zero nor close to zero when the temperature T of the water is 0° C. or less at atmospheric pressure, for example, when T is about −2° C., then it means that the water is non-demineralized.

[0060] FIG. 3 shows an example method 100 of controlling water injection in an internal combustion engine for a motor vehicle in case of freezing cold weather, in accordance with the present disclosure. At step Start, method 100 starts. At step a, method determines the temperature T of the water contained in a water injection tank around a conductivity sensor. At step b, method controls the quality of the water. At step c, method prevents water injection if the quality of the water is disapproved. At step d, method allows water injection if the quality of the water is approved. Method 100 may then end.

[0061] Step b comprises two sub-steps: sub-step b10 and sub-step b20. At sub-step b10, method 100 disapproves the quality of the water if the electrical conductivity σ of the water is not zero nor close to zero when the determined temperature T of the water is 0° C. or less. At sub-step b20, method 100 approves the quality of the water if the electrical conductivity σ of the water is zero or close to zero when the determined temperature T of the water is higher than a predetermined threshold T.sub.min, wherein the value of the predetermined T.sub.min is higher than −4° C., preferably higher than −2° C.

[0062] When T<T.sub.min, method 100 heats the water until T reaches at least T.sub.min.

[0063] At sub-steps b10 and b20, method 100 compares the electrical conductivity σ of the water to a predetermined threshold of electrical conductivity σ.sub.max. In the context of the invention, the electrical conductivity σ of the water is close to zero when its value σ is less than or equal to the predetermined threshold of electrical conductivity σ.sub.max, wherein the value of the predetermined threshold of electrical conductivity σ.sub.max is 30 μS/cm, more preferably σ.sub.max is 20 μS/cm, and most preferably σ.sub.max is 10 μS/cm.

[0064] FIG. 4 shows a water injection system 10 configured for implementing the method of controlling water injection in an internal combustion engine for a motor vehicle in case of freezing cold weather. The water injection system comprises: [0065] a water injection tank 1 for storing water 30, [0066] an electrical conductivity sensor 3 for sensing the electrical conductivity σ of the water in the water injection tank 1, [0067] a temperature determining means 2 for determining the temperature T of the water in the water injection tank 1 around the conductivity sensor 3, [0068] a comparator 4 for comparing the sensed electrical conductivity σ to the predetermined threshold of electrical conductivity σ.sub.max, [0069] a water injection pump 5 for supplying water from the water injection tank 1 to an injection line 6 configured to be connected to the internal combustion engine, [0070] a first electronic control unit 7 for approving or disapproving the quality of the water.

[0071] It's to be understand that the temperature determining means can be a temperature sensor or any other means for determining the temperature of the water in the specific zone around the conductivity sensor.

[0072] The water injection system 10 is configured for sensing the electrical conductivity σ of water in the water injection tank 1 even when the determined temperature T is below 0° C. In addition, the water injection system 10 is advantageously configured for sensing the electrical conductivity σ of the water in the water injection tank 1 when the determined temperature T is higher than the predetermined threshold T.sub.min.

[0073] Advantageously, the comparator 4 is part of the first electronic control unit 7.

[0074] Advantageously, the first electronic control unit 7 controls the water injection pump 5 for allowing or preventing water injection, based on the quality of the water.

[0075] The water injection system 10 further comprises a heater 8 for heating the water 30 stored in the water injection tank 1 when T<T.sub.min until T reaches at least T.sub.min.

[0076] Advantageously, the temperature sensor 2 and the electrical conductivity sensor 3 are close to each other, so that the temperature measured by the temperature sensor 2 substantially corresponds to the temperature of the water around (which means very closed to) the electrical conductivity sensor 3.

[0077] In a very interesting embodiment, the temperature sensor 2 and the electrical conductivity sensor 3 are part of a quality sensor device 9.

[0078] The temperature sensor 2 and the electrical conductivity sensor 3 comprise each a sensing surface, and the distance between the sensing surface of the temperature sensor 2 and the sensing surface of the electrical conductivity sensor 3 is 30 mm or less.

[0079] The water injection tank 1 comprises a water delivery module 11.

[0080] Advantageously, the water delivery module 11 comprises the water injection pump 5, the temperature sensor 2, the electrical conductivity sensor 3 and the heater 8.

[0081] FIG. 4 shows also an internal combustion engine system 20 configured for implementing the method of controlling water injection in an internal combustion engine for a motor vehicle in case of freezing cold weather. The internal combustion engine system 20 comprises an internal combustion engine 21 and the water injection system 10.

[0082] The internal combustion engine system 20 comprises a second electronic control unit 22 for commanding and controlling the first electronic control unit 7, for example, for allowing or preventing water injection by controlling the water injection pump 5.

[0083] In an alternative arrangement (not shown), the comparator is part of the second electronic control unit 22 and the second electronic control unit 22 controls the water injection pump 5 for allowing or preventing water injection, based on the quality of the water. Therefore, the first electronic control unit 7 can be replaced with the second electronic control unit 22 and the first electronic control unit 7 can be removed.

[0084] The internal combustion engine system 20 is part of a motor vehicle (not shown) configured for implementing the method of controlling water injection in an internal combustion engine fora motor vehicle in case of freezing cold weather.

[0085] Method 100 may be carried out by the first electronic control unit 7 and may be stored at the first electronic control unit 7 as executable instructions in non-transitory memory. Instructions for carrying out method 100 may be executed by the first electronic control unit 7 based on instructions stored on the non-transitory memory of the first electronic control unit 7 and in conjunction with measurement information received from the temperature determining means 2 and the electrical conductivity sensor 3.

LIST OF REFERENCES

[0086] 1: water injection tank [0087] 2: temperature determining means [0088] 3: electrical conductivity sensor [0089] 4: comparator [0090] 5: water injection pump [0091] 6: injection line [0092] 7: first electronic control unit [0093] 8: heater [0094] 9: quality sensor device [0095] 10: water injection system [0096] 11: water delivery module [0097] 20: internal combustion engine system [0098] 21: internal combustion engine [0099] 22: second electronic control unit [0100] 30: water