Claims:CLAIMS

We Claim

1. A method (10) to determine fuel evaporation from engine oil from when an engine is switched off to when the engine is switched on, the method (10) comprising:
determining (12) whether an engine control unit is in an off state;
determining (14) a mass of fuel accumulated over time in an oil sump of an engine when the engine control unit is in the off state;
storing (14) the mass of fuel accumulated over time in a memory unit;
determining (16) whether the engine control unit is in an on state;
calculating (18) a mass of fuel that evaporated from then oil sump of the engine between a time interval from when the engine was switched off to when the engine is switched on;
determining (20) a mass of fuel that evaporated from then oil sump of the engine between a time interval from when the engine was switched off to when the engine is switched on;
determining (22) a difference of a mass of fuel that evaporated from then oil sump of the engine between a time interval from when the engine was switched off to when the engine is switched on from the mass of fuel accumulated over time in the oil sump of the engine when the engine control unit is in the off state;
determining (24) an actual available mass of fuel accumulated over time in the oil sump of the engine based on the difference of a mass of fuel that evaporated from then oil sump of the engine between a time interval from when the engine was switched off to when the engine is switched on from the mass of fuel accumulated over time in the oil sump of the engine when the engine control unit is in the off state; and
determining (26) a level of dilution of oil in the oil sump based on a quantity of fuel that is present in the oil sump, wherein the quantity of fuel that is present in the oil sump is based on the determined actual available mass of fuel accumulated over time in the oil sump of the engine.

2. A method (10) to determine fuel evaporation from engine oil from when an engine is switched off to when the engine is switched on in accordance with Claim 1, wherein calculating (18) a mass of fuel that evaporated from then oil sump of the engine between a time interval from when the engine was switched off to when the engine is switched on is based on one of an engine control unit and an engine off time (28).

3. A method (10) to determine fuel evaporation from engine oil from when an engine is switched off to when the engine is switched on in accordance with Claim 1, wherein calculating (18) a mass of fuel that evaporated from then oil sump of the engine between a time interval from when the engine was switched off to when the engine is switched on is based on an evaporation rate of the fuel with reference to an oil temperature (30).

4. A method (10) to determine fuel evaporation from engine oil from when an engine is switched off to when the engine is switched on in accordance with Claim 1, wherein calculating (18) a mass of fuel that evaporated from then oil sump of the engine between a time interval from when the engine was switched off to when the engine is switched on is based on a cooling rate of oil that is present in the oil sump with reference to ambient temperature (32).
, Description:Complete Specification:

The following specification describes and ascertains the nature of this invention and the manner in which it is to be performed.
Field of the invention
[0001] This invention relates to a method to determine fuel evaporation from engine oil, and more specifically to a method to determine fuel evaporation from engine oil from when an engine is switched off to when the engine is switched on.

Background of the invention
[0002] CN 111396171 A describes an engine oil dilution calculation method. The engine oil dilution calculation method comprises the following steps of calculating the fuel oil quantity of engine oil when the engine oil needs to be replaced, and outputting an engine oil dilution coefficient according to the rail pressure and the MAP of the far-backward oil injection quantity. The engine oil dilution calculation method further comprises conducting unit conversion to obtain the fuel oil growth rate of the engine oil in unit time, correcting environmental factors to obtain the fuel oil growth rate of the oil in the engine oil after correction of the environmental factors, correcting the EGR rate, and obtaining the fuel oil growth rate with the corrected EGR rate after unit conversion. The engine oil dilution calculation method further comprises correcting oil volatilization, obtaining the fuel oil evaporation rate in unit time, calculating the fuel oil growth rate of the engine oil in unit time, obtaining the oil content of the engine oil through the and the time integral, and displaying a prompt for replacing engine oil on an instrument when compared with the prior art. The engine oil dilution calculation method has the advantages of low cost and good use effect.

Brief description of the accompanying drawing
[0003] Figure 1 illustrates a flowchart depicting a method to determine fuel evaporation from engine oil in one embodiment of the invention.

Detailed description of the embodiments
[0004] Figure 1 illustrates a method 10 to determine fuel evaporation from engine oil from when an engine is switched off to when the engine is switched on. The method 10 comprises determining 12 whether an engine control unit is in an off state, determining 14 a mass of fuel accumulated over time in an oil sump of an engine when the engine control unit is in the off state, storing 14 the mass of fuel accumulated over time in a memory unit, and determining 16 whether the engine control unit is in an on state. The method further comprises calculating 18 a mass of fuel that evaporated from then oil sump of the engine between a time interval from when the engine was switched off to when the engine is switched on, determining 20 a mass of fuel that evaporated from then oil sump of the engine between a time interval from when the engine was switched off to when the engine is switched on, determining 22 a difference of a mass of fuel that evaporated from then oil sump of the engine between a time interval from when the engine was switched off to when the engine is switched on from the mass of fuel accumulated over time in the oil sump of the engine when the engine control unit is in the off state, determining 24 an actual available mass of fuel accumulated over time in the oil sump of the engine based on the difference of a mass of fuel that evaporated from then oil sump of the engine between a time interval from when the engine was switched off to when the engine is switched on from the mass of fuel accumulated over time in the oil sump of the engine when the engine control unit is in the off state, and determining 26 a level of dilution of oil in the oil sump based on a quantity of fuel that is present in the oil sump, wherein the quantity of fuel that is present in the oil sump is based on the determined actual available mass of fuel accumulated over time in the oil sump of the engine.

[0005] Figure 1 illustrates a method 10 to determine fuel evaporation from engine oil from when an engine is switched off to when the engine is switched on in one embodiment of the invention. The method 10 comprises determining 12 whether an engine control unit is in an off state or in an on state. Once the engine control unit is determined to be in an off state, a mass of fuel accumulated over time in an oil sump of the engine when the engine control unit was just switched off to be in the off state is determined 14. The mass of fuel accumulated over time in an oil sump of the engine when the engine control unit was just switched off is stored 14 in the memory unit for further processing.

[0006] The method further comprises determining 16 whether the engine control unit is in an on state or in an off state. Once the engine control unit is determined to be in an on state, the engine control unit calculates 18 a mass of fuel that evaporated from the oil sump of the engine between a time interval from when the engine was switched off to when the engine is switched on. The engine control unit therein determines 20 a mass of fuel that evaporated from the oil sump of the engine between a time interval from when the engine was switched off to when the engine is switched on. Therefore, the mass of fuel that evaporated from the oil sump is equal to the mass of the fuel that evaporated during an engine off condition of the vehicle. Hence, by knowing the mass of the fuel that evaporated during an engine off condition of the vehicle, the quantity of fuel that is remaining within the oil sump of the engine may be more accurately determined. Therein, the engine control unit subtracts 22 the mass of the fuel that evaporated during an engine off condition of the vehicle from the mass of fuel accumulated over time in the oil sump of the engine when the engine control unit is in the off state. The difference between the mass of the fuel that evaporated during an engine off condition of the vehicle and the mass of fuel accumulated over time in the oil sump of the engine is equal to the mass of fuel that is remaining within the oil sump of the engine.

[0007] In an exemplary embodiment, the method 10 comprises determining 24 an actual available mass of fuel accumulated over time in the oil sump of the engine based on the difference of a mass of fuel that evaporated from then oil sump of the engine between a time interval from when the engine was switched off to when the engine is switched on from the mass of fuel accumulated over time in the oil sump of the engine when the engine control unit is in the off state. Once the difference of the mass of fuel that evaporated from then oil sump of the engine between the time interval from when the engine was switched off to when the engine is switched on from the mass of fuel accumulated over time in the oil sump of the engine when the engine control unit is in the off state is known, a quantity of fuel the remains within the oil sump that is responsible for diluting the oil within the oil sump may be determined.

[0008] In an exemplary embodiment, a level of dilution of oil in the oil sump is determined 26 based on a quantity of fuel that is present in the oil sump after the mass of fuel that evaporated from then oil sump of the engine between the time interval from when the engine was switched off to when the engine is switched on has been accounted for. More specifically, the quantity of fuel that is present in the oil sump after the mass of fuel that evaporated from then oil sump of the engine between the time interval from when the engine was switched off to when the engine is switched on is based on the determined actual available mass of fuel accumulated over time in the oil sump of the engine by inputting the mass of fuel accumulated over time in the oil sump of the engine divided by the density of the fuel that is present in the oil sump.

[0009] In an exemplary embodiment, calculating 18 a mass of fuel that evaporated from then oil sump of the engine between a time interval from when the engine was switched off to when the engine is switched on is based on one of an engine control unit / engine off time 28. In an alternate exemplary embodiment, calculating 18 a mass of fuel that evaporated from then oil sump of the engine between a time interval from when the engine was switched off to when the engine is switched on is based on an evaporation rate of the fuel with reference to an oil temperature 30. In yet another alternate exemplary embodiment, calculating 18 a mass of fuel that evaporated from then oil sump of the engine between a time interval from when the engine was switched off to when the engine is switched on is based on a cooling rate of oil that is present in the oil sump with reference to an ambient air temperature 32.

[0010] It must be understood that the embodiments explained above are only illustrative and do not limit the scope of the disclosure. Many modifications in the embodiments with regard to dimensions of various components are envisaged and form a part of this invention. The scope of the invention is only limited by the scope of the claims.