JP2017150372A - Oil dilution amount determination method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oil dilution amount determination method capable of determining engine oil dilution amount of a diesel engine during an operation of the diesel engine without using an oil sensor.SOLUTION: In an oil dilution amount determination method for determining engine oil dilution amount in a diesel engine, a correlation map of fuel injection amount of the diesel engine and the engine oil dilution amount is prepared (map preparation process), and then, the diesel engine is driven (driving process). Then, feedback control of the fuel injection amount is performed so that the rotational speed of the diesel engine reaches a predetermined value (control process). After that, on the basis of the correlation map, the engine oil dilution amount is calculated from the fuel injection amount (calculation process).SELECTED DRAWING: Figure 1

Description

  The present invention relates to an oil dilution amount determination method, and more particularly to an oil dilution amount determination method for determining an engine oil dilution amount in a diesel engine.

  Conventionally, a diesel particulate filter (DPF; Diesel particulate filter) is provided in an exhaust path of a diesel engine in order to collect and remove exhaust particulates (PM) contained in the exhaust gas. More specifically, PM contained in the exhaust gas in the diesel engine is collected in the DPF, and the exhaust gas from which the PM has been removed is released to the outside. The PM collected in the DPF is heated and burned at a predetermined timing, and the DPF is regenerated.

  In the regeneration of the DPF, for example, a method is known in which an oxidation catalyst is provided on the upstream side of the DPF, and fuel is late post-injected (post-fuel injection) into the diesel engine at a predetermined timing. In this method, the late post-injected fuel is oxidized (combusted) in the oxidation catalyst. The DPF is heated by the oxidation (combustion), and the PM deposited on the DPF is combusted.

  On the other hand, when late post-injecting fuel into a diesel engine, the engine oil in the diesel engine may be diluted by the fuel.

  When engine oil is diluted, the viscosity of the engine oil decreases, and the diesel engine may be damaged, such as seizure.

  Therefore, in order to adjust the frequency of late post-injection and to replace diluted engine oil, it is required to determine the amount of engine oil dilution and to warn when the amount exceeds the reference value. The Specifically, for example, in an internal combustion engine where fuel post-injection is performed, an oil sensor that contacts engine oil is provided, and a warning signal is output when the oil level determined by the oil sensor exceeds a predetermined value. A method of operating an internal combustion engine has been proposed (see, for example, Patent Document 1).

JP 2008-505283 A

  On the other hand, in a diesel engine, it is desired to determine the engine oil dilution amount without using an oil sensor from the viewpoint of efficiency in determining the engine oil dilution amount and cost reduction.

  In addition, in order to control the operating conditions of the diesel engine, it is also desired to determine the oil dilution amount in real time during the operation of the diesel engine.

  An object of the present invention is to provide an oil dilution amount determination method capable of determining an engine oil dilution amount of a diesel engine without using an oil sensor and during operation of the diesel engine.

  The present invention [1] is an oil dilution amount determination method for determining an engine oil dilution amount in a diesel engine, and a map creation step of creating a correlation map between the fuel injection amount of the diesel engine and the engine oil dilution amount The fuel injection amount based on the correlation map based on the driving step for driving the diesel engine, the control step for feedback control of the fuel injection amount so that the rotational speed of the diesel engine becomes a predetermined value, and An oil dilution amount determination method including a calculation step of calculating the engine oil dilution amount is included.

  Further, the present invention [2] further includes a map adjustment for measuring the fuel injection amount when the diesel engine is driven for the first time after changing the engine oil after the map creating step, and adjusting the correlation map. An oil dilution amount determination method according to the above [1], comprising a process.

  According to the oil dilution amount determination method of the present invention, an oil sensor is used to calculate the engine oil dilution amount from the fuel injection amount using a correlation map between the fuel injection amount of the diesel engine and the engine oil dilution amount. In addition, the engine oil dilution amount of the diesel engine can be determined during operation of the diesel engine.

FIG. 1 is a schematic diagram showing an embodiment of a diesel engine in which the oil dilution amount determination method of the present invention is employed. FIG. 2 is a schematic diagram of a correlation map used in the oil dilution amount determination method of the present invention. FIG. 3 is a correlation map obtained in Reference Example 1.

1. Configuration of Diesel Engine System FIG. 1 is a schematic diagram showing an embodiment of a diesel engine system in which the oil dilution amount determination method of the present invention is adopted.

  In FIG. 1, a diesel engine system 1 is a power source mounted on a vehicle, for example, and includes a diesel engine 2 to which fuel such as light oil is supplied, and an intake section 3 for introducing air into the diesel engine 2. An exhaust part 5 for discharging exhaust gas generated in the diesel engine 2, a DPF unit 8 for removing particulates from the exhaust gas, an output sensor 9 as a detection means for detecting the output of the diesel engine 2, and fuel injection And a control unit 10 as control means for controlling the operation of a valve 19 (described later).

  In FIG. 1, the diesel engine 2 includes a cylinder block 11, a piston 12, a cylinder head 14, an oil pan 15, and a fuel supply unit 4.

  The cylinder block 11 includes a cylindrical cylinder portion (cylinder) 11a in which the piston 12 is accommodated, and a substantially box-shaped crankcase 11b in which a crankshaft 6 (described later) is accommodated below the cylinder portion 11a in the vertical direction. ing.

  In the diesel engine 2, the number of cylinder blocks 11 is not particularly limited, and is one or more (for example, 2 to 6). That is, the diesel engine 2 is a single cylinder type or a multi-cylinder type diesel engine.

  Specific examples of the diesel engine 2 include a one-cylinder diesel engine, a two-cylinder diesel engine, a three-cylinder diesel engine, a four-cylinder diesel engine, and a six-cylinder diesel engine.

  The diesel engine 2 is preferably a multi-cylinder type (more preferably, a three-cylinder type) diesel engine 2. In FIG. 1, only one cylinder block 11 is shown, and the other cylinder blocks 11 are omitted.

  Piston 12 is provided in order to compress air in cylinder part 11a, and is slidably accommodated in cylinder part 11a. The piston 12 is provided with a crankshaft 6 so as to be rotatable in the crankcase 11b.

  The cylinder head 14 is disposed on the upper side in the vertical direction of the cylinder block 11 so as to seal the cylinder block 11, and a combustion chamber 20 is formed between the piston 12 and the cylinder head 14. In the combustion chamber 20, the fuel injected from the fuel injection valve 19 (described later) and the air supplied from the intake section 3 (described later) can be mixed and combusted.

  In addition, the cylinder head 14 discharges exhaust gas generated in the combustion chamber 20 to an exhaust port 5 (described later) and an intake port 21 for introducing air supplied from the intake portion 3 (described later) into the combustion chamber 20. For this purpose, an exhaust port 22 for opening and closing the intake port 21 and an exhaust valve 25 for opening and closing the exhaust port 22 are provided. The intake valve 24 and the exhaust valve 25 are electrically connected to a control unit 10 (described later), and can be opened and closed according to an electrical signal from the control unit 10 (described later).

  The oil pan 15 is a container for storing engine oil, and is disposed on the lower side in the vertical direction of the crankcase 11b. The oil pan 15 stores engine oil (lubricating oil).

  The fuel supply unit 4 is a unit that supplies fuel to the combustion chamber 20, and specifically includes a fuel tank 17, a fuel supply pipe 18, and a fuel injection valve 19.

  The fuel tank 17 is a tank that stores fuel for diesel engines (for example, light oil), and is formed of, for example, a heat and pressure resistant container.

  The fuel supply pipe 18 is a pipe for supplying fuel from the fuel tank 17 to each combustion chamber 20. The upstream end is connected to the fuel tank 17, and the downstream side is connected to the fuel injection valve 19. ing. The fuel supply pipe 18 is provided with a fuel pump (not shown) and the like so that the fuel in the fuel tank 17 can be supplied to the fuel injection valve 19 by driving.

  The fuel injection valve 19 is an injection valve for injecting fuel into each combustion chamber 20, and is connected to the cylinder head 14 so as to face the combustion chamber 20. Each fuel injection valve 19 is electrically connected to a control unit 10 (described later), and can inject fuel into the combustion chamber 20 in accordance with an electrical signal from the control unit 10 (described later). The injection amount can be adjusted by the valve opening.

  In such a diesel engine 2, the lifting and lowering motion of the piston 12 is repeated. For example, an intake process, a compression process, an explosion process, and an exhaust process are sequentially performed. As a result, fuel is combusted in the combustion chamber 20 and the crankshaft 6 rotates to output power.

  The intake section 3 is a unit for introducing air into the combustion chamber 20, and specifically includes an intake pipe 13 and a compressor 16.

  The intake pipe 13 is provided to introduce air into each combustion chamber 20 of the diesel engine 2, and the upstream side is open to the outside (outside air), and the downstream side is connected to the intake port 21 of the cylinder head 14. When the diesel engine 2 has a plurality of cylinder blocks 11, the intake pipe 13 is formed as a branch manifold that branches on the downstream side, and the branch end is connected to the intake port 21 of each cylinder head 14.

  The compressor 16 is a device for sucking air from the outside, and is interposed in the intake pipe 13.

  Further, although not shown in detail, an air cleaner (not shown) for removing impurities from the air and an air cooler (not shown) for cooling the air as necessary in the flow direction of the intake pipe 13 as needed. Etc.) are intervened.

  Note that a throttle valve for adjusting the air amount may be interposed in the middle of the flow direction of the intake pipe 13, but the diesel engine 2 may not include a throttle valve, unlike a gasoline engine. .

  The exhaust unit 5 is a unit that exhausts exhaust gas (fuel combustion gas) generated in the combustion chamber 20 from the combustion chamber 20, and specifically includes an exhaust pipe 23.

  The exhaust pipe 23 is an exhaust manifold provided to exhaust the exhaust gas from each combustion chamber 20 of the diesel engine 2 to the outside, and the upstream side is connected to the exhaust port 22 of each cylinder head 14 and the downstream side is the external It is open to (outside air). When the diesel engine 2 has a plurality of cylinder blocks 11, the exhaust pipe 23 is formed as a branch manifold that branches on the upstream side, and the branch end is connected to the exhaust port 22 of each cylinder head 14.

  Further, a turbocharger 30 for converting the exhaust gas into power is interposed in the middle of the exhaust pipe 23 in the flow direction. The turbocharger 30 may be a known turbocharger. For example, a turbocharger including a turbine (not shown) that rotates by the flow of exhaust gas, a shaft (not shown) that transmits the rotation of the turbine (not shown), and the like. Etc.

  Further, the DPF unit 8 is interposed in the flow direction of the exhaust pipe 23, specifically, downstream of the turbocharger 30.

  The DPF unit 8 is an apparatus for removing particulate matter (PM; Particulate Matter (details will be described later)) from the exhaust gas, and includes a case 26 interposed in the exhaust pipe 23 and particulates disposed in the case 26. A collection filter (DPF; Diesel particulate filter) 6 and an oxidation catalyst 7 are provided.

  The case 26 is not particularly limited. For example, the case 26 is a cylindrical heat-resistant pressure-resistant container having a diameter larger than that of the exhaust pipe 23, and is interposed in the exhaust pipe 23. Further, the case 26 is provided with a temperature sensor (not shown) for detecting the internal temperature as required.

  The DPF 6 is a filter for collecting fine particles in the exhaust gas, and is interposed in the exhaust pipe 23. Specifically, the DPF 6 is formed in a porous cylindrical shape, and is disposed in the case 26 in the middle of the exhaust gas flow direction in the exhaust pipe 23.

  The oxidation catalyst 7 is a catalyst that oxidizes (combusts) the fuel (unburned gas) when it comes into contact, and a known oxidation catalyst such as a metal oxide is used.

  Such an oxidation catalyst 7 is coated on, for example, a cylindrical honeycomb catalyst carrier and disposed in the case 26 on the upstream side of the DPF 6 in the exhaust gas flow direction.

  The exhaust pipe 23 may be provided with a muffler (not shown) or the like downstream of the turbocharger 30 and the DPF unit 8 as necessary.

  The output sensor 9 is a sensor that detects the output (load) of the diesel engine 2, and specifically, a known sensor that measures the rotational speed of the diesel engine 2 is employed. Moreover, the output sensor 9 can also measure the torque of the diesel engine 2 etc. as needed.

  The control unit 10 is a unit that executes electrical control in the diesel engine system 1 (for example, ECU: Electronic Control Unit), and includes a microcomputer that includes a CPU, a ROM, a RAM, and the like.

  As indicated by broken lines in FIG. 1, the control unit 10 is electrically connected to the intake valve 24 and the exhaust valve 25 so that the opening and closing thereof can be controlled. Further, the control unit 10 is electrically connected to the output sensor 9 and the fuel injection valve 19 as indicated by a broken line in FIG. 1. The diesel engine 2 detected by the output sensor 9 will be described in detail later. The operation of the fuel injection valve 19 can be controlled according to the output (number of rotations).

  The diesel engine system 1 preferably includes a cooling system 31.

  The cooling system 31 is a system that cools the diesel engine 2 (see the thick chain line in FIG. 1) with cooling water. For example, the water tank 32 that stores the cooling water and the cooling water circulate along the outer periphery of the diesel engine 2. And a radiator (not shown) for cooling the water after the diesel engine 2 is cooled (that is, heated).

  The cooling system 31 includes a water temperature sensor (not shown) that detects the temperature of the cooling water. For example, the water temperature sensor 33 is disposed in the water tank 32 so that the temperature of the cooling water can be detected. Further, the water temperature sensor 33 is electrically connected to the control unit 10 as indicated by a broken line in FIG. 1, and the temperature of the cooling water can be input to the control unit 10.

  Furthermore, the diesel engine system 1 can be provided with an exhaust gas recirculation (EGR) flow path 28 (see the broken line in FIG. 1) as necessary from the viewpoint of improving fuel efficiency.

  The EGR flow path 28 is a bypass pipe that connects an intermediate portion in the flow direction of the exhaust pipe 23 (between the turbocharger 30 and the DPF unit 8) and an intermediate portion in the flow direction of the intake pipe 13 (downstream side of the compressor 16). In the middle of the flow direction, an opening / closing control valve (not shown) is provided. When such an EGR flow path 28 is provided, the exhaust gas in the exhaust pipe 23 can be circulated to the intake pipe 13 via the EGR flow path 28, and as a result, the exhaust gas is again supplied to the diesel engine. The engine 2 can be supplied.

2. Driving Diesel Engine System In the diesel engine system 1, the piston 12 is repeatedly moved up and down in each cylinder portion 11a, and an intake process, a compression process, an explosion process, and an exhaust process are sequentially performed.

  Specifically, the compressor 16 is driven, the intake valve 24 is operated, and the intake port 21 is opened, so that air passes through the intake pipe 13 and is supplied to each combustion chamber 20. (Intake process).

  Thereafter, the intake valve 24 is operated, the intake port 21 of the cylinder head 14 is closed, and the air is compressed by the pistons 12 that move up and down (up) in each cylinder block 11 (compression process).

  When the piston 12 is lifted, the fuel in the fuel tank 17 passes through the fuel supply pipe 18 and the fuel injection valve 19 at a predetermined timing (that is, when the air compression rate reaches a predetermined value). It is supplied to the combustion chamber 20. As a result, the fuel spontaneously ignites and explodes in the compressed high-temperature and high-pressure air (explosion process).

  Thereby, the fuel is burned and exhaust gas is generated in the combustion chamber 20.

  Thereafter, the exhaust valve 25 is operated and the exhaust port 22 is opened, whereby the exhaust gas in the combustion chamber 20 passes through the exhaust pipe 23 and is discharged to the outside (exhaust process).

  In this exhaust process, the exhaust gas passes through the turbocharger 30 interposed in the exhaust pipe 23. Thereby, the flow of exhaust gas is converted into motive power.

  On the other hand, the exhaust gas usually contains fine particles (PM). PM includes, for example, black smoke, soluble organic matter (SOF), sulfate in which sulfur contained in fuel is chemically changed, and the like.

  Such PM is legally restricted from being released to the outside air. Therefore, in the diesel engine system 1 described above, PM is collected in the DPF 6 when the exhaust gas passes through the exhaust pipe 23. That is, the exhaust gas after passing through the DPF 6 has a reduced PM content. Therefore, the exhaust gas after passing through the DPF 6 can be released to the outside air.

  Further, when the diesel engine 2 is driven, the engine oil in the oil pan 15 is pumped up by a pump (not shown) or the like and supplied to, for example, a sliding portion of the piston 12. As a result, wear and seizure due to sliding are suppressed.

3. Regeneration of DPF As described above, the DPF 6 collects PM. However, as the DPF 6 collects PM, the DPF 6 causes clogging, and the collection performance decreases. Further, when the DPF 6 is clogged, the operation efficiency of the diesel engine system 1 may be reduced or the diesel engine system 1 may be damaged.

  Therefore, in the diesel engine system 1, the DPF 6 is heated at a predetermined timing. As a result, the PM collected on the DPF 6 is burned and the DPF 6 is regenerated.

  Specifically, PM is burned at, for example, 550 ° C. or higher, preferably 600 ° C. or higher. Therefore, by heating DPF6 to 600 degreeC or more preferably, PM deposited on DPF6 can be burned and DPF6 can be regenerated | regenerated.

  For example, if the temperature of the exhaust gas generated in the explosion process is equal to or higher than a predetermined temperature (preferably 600 ° C.), the DPF 6 is heated when the exhaust gas passes through the exhaust pipe 23 in the exhaust process.

  As a result, the DPF 6 is heated to a predetermined temperature (preferably 600 ° C.) or higher, and the PM collected in the DPF 6 is burned.

  On the other hand, for example, depending on the driving conditions of the diesel engine system 1, the temperature of the exhaust gas generated in the explosion process may be lower than a predetermined temperature (preferably 600 ° C.).

  In such a case, when the exhaust gas passes through the exhaust pipe 23, the DPF 6 cannot be heated to a predetermined temperature (preferably 600 ° C.) or higher, and PM may not be combusted.

  Therefore, in the diesel engine system 1, fuel is post-injected into the combustion chamber 20 in order to heat the DPF 6 to a predetermined temperature (preferably 600 ° C.) or more during driving of the diesel engine 2.

  The post-injection is an injection for supplying fuel to the exhaust pipe 23, not for supplying the fuel to the above-described explosion process. Specifically, in post-injection, fuel is injected into the combustion chamber 20 in the exhaust process described above, not in the explosion process described above.

  The fuel post-injected into the combustion chamber 20 is mixed with the exhaust gas generated in the explosion process. Then, the fuel is supplied to the exhaust pipe 23 together with the exhaust gas in the exhaust process.

  The fuel supplied to the exhaust pipe 23 comes into contact with the oxidation catalyst 7 of the DPF unit 8 and is oxidized (burned). The exhaust gas is heated by oxidation (combustion) of the fuel, and the heated exhaust gas is filled in the DPF unit 8 and supplied to the DPF 6. As a result, the temperature in the DPF unit 8 rises and the PM deposited on the DPF 6 is burned.

  In this manner, by injecting fuel into the combustion chamber 20, the exhaust gas is heated, and the DPF 6 can be heated to a predetermined temperature (preferably 600 ° C.) or more to burn PM.

4). On the other hand, when the fuel is post-injected as described above, the engine oil in the diesel engine 2 may be diluted by the post-injected fuel.

  That is, post-injected fuel (light oil, etc.) may not be burned in the combustion chamber 20, may not be discharged to the exhaust pipe 23, and may drip into the oil pan 15, and engine oil in the oil pan 15 may be fueled. May be diluted with (light oil, etc.).

  When the engine oil is diluted, the engine oil viscosity decreases, and damage such as wear or seizure may occur during the driving of the diesel engine 2.

  Therefore, it is required to determine the engine oil dilution amount, appropriately adjust the frequency of post injection according to the engine oil dilution amount, and further replace the diluted engine oil.

  In particular, it is desired to determine the engine oil dilution amount without using an oil sensor from the viewpoint of efficiency in determining the engine oil dilution amount and cost reduction.

  In addition, in order to control the operating conditions of the diesel engine, it is also desired to determine the oil dilution amount in real time during the operation of the diesel engine.

  Therefore, in the diesel engine system 1 described above, the engine oil dilution amount (and dilution ratio) is determined by the following oil dilution amount determination method during operation of the diesel engine.

5. Oil Dilution Amount Determination Method (1) In this method, first, a correlation map between the fuel injection amount of the diesel engine 2 and the engine oil dilution amount is created (map creation step).

  The fuel injection amount and the engine oil dilution amount have a correlation as described below.

  That is, in general, under the temperature environment where the diesel engine 2 is driven, the viscosity of the engine oil is higher than the viscosity of the fuel of the diesel engine 2.

  Therefore, when the dilution amount of the engine oil is relatively high (that is, when the concentration of the engine oil is relatively low), the viscosity of the engine oil becomes relatively low. In such a case, when the diesel engine 2 is driven, the viscous resistance due to the engine oil is relatively low, so that the mechanical loss (mechanical loss) for driving is relatively low. As a result, the amount of fuel injection required to drive the diesel engine 2 at a predetermined rotational speed is relatively small.

  On the other hand, when the dilution amount of the engine oil is relatively low (that is, when the concentration of the engine oil is relatively high), the viscosity of the engine oil becomes relatively high. In such a case, when the diesel engine 2 is driven, the viscous resistance due to the engine oil is relatively high, so that the mechanical loss (mechanical loss) for driving becomes relatively high. As a result, the amount of fuel injection required to drive the diesel engine 2 at a predetermined rotational speed is relatively large.

  Accordingly, engine oils adjusted to various dilution amounts are prepared in advance, and the fuel injection amount necessary for driving the diesel engine 2 at a predetermined rotational speed when each engine oil is used is measured. Then, based on the obtained data, the relationship between the fuel injection amount necessary for driving the diesel engine 2 at a predetermined rotational speed and the engine oil dilution amount is mapped to create a correlation map. A schematic diagram of a correlation map used in this method is shown in FIG.

  As shown in FIG. 2, in order to drive the diesel engine 2 at a predetermined rotational speed, the higher the engine oil dilution amount (that is, the lower the engine oil concentration and the lower the viscosity), the more proportional combustion occurs. The injection amount is reduced.

  (2) Next, in this method, the diesel engine 2 is driven (drive process).

  In driving the diesel engine 2, as described above, fuel is injected into the combustion chamber 20 from the fuel injection valve 19, and the piston 12 is repeatedly moved up and down, and the intake process, compression process, explosion process, and exhaust process are sequentially performed. The

  (3) Next, in this method, the fuel injection amount is feedback-controlled so that the rotational speed of the diesel engine 2 becomes a predetermined value (control process).

  That is, in this method, the rotational speed of the diesel engine 2 is detected by the output sensor 9, and the detection signal is input to the control unit 10.

  When the rotational speed of the diesel engine 2 is higher than a preset numerical value, the fuel injection amount by the fuel injection valve 19 is decreased. Further, when the rotational speed of the diesel engine 2 is lower than a preset numerical value, the fuel injection amount by the fuel injection valve 19 is increased. Thereby, it adjusts so that the rotation speed of the diesel engine 2 may become equivalent to the numerical value set beforehand.

  (4) Thereafter, in this method, the engine oil dilution amount is calculated from the fuel injection amount based on the correlation map obtained in the map creation step (calculation step).

  That is, it was created in the step (1) from the fuel injection amount (for example, see point A in FIG. 2) required to drive the diesel engine 2 at a predetermined rotational speed in the step (3). With reference to the correlation map (for example, see the broken line arrow in FIG. 2), the dilution amount of the engine oil of the diesel engine 2 (for example, see the point B in FIG. 2) is calculated.

  According to such an oil dilution amount determination method, an oil sensor is used to calculate the engine oil dilution amount from the fuel injection amount using a correlation map between the fuel injection amount of the diesel engine 2 and the engine oil dilution amount. In addition, the engine oil dilution amount of the diesel engine can be determined during operation of the diesel engine.

  Then, during operation of the diesel engine, the operation state of the diesel engine 2 can be appropriately adjusted according to the engine oil dilution amount, and the frequency of post injection can be adjusted.

  Further, when the engine oil dilution amount exceeds the reference value, a warning is displayed and the engine oil can be replaced.

  In this method, preferably, after changing the engine oil, the fuel injection amount at the time of driving the first diesel engine 2 is measured, and the correlation map is adjusted (map adjustment step).

  That is, in this method, after the engine oil is changed, the diesel engine 2 is driven so as to have a predetermined rotational speed, and the fuel injection amount is measured. Then, assuming that the fuel injection amount obtained at this time is the fuel injection amount with the engine oil dilution amount 0 (dilution rate 0%), the correlation map is zeroed.

  Thereby, the engine oil dilution amount can be calculated from the fuel injection amount with higher accuracy.

  The temperature condition in the above method is not particularly limited as long as it is generally a temperature at which the diesel engine 2 is driven. For example, the temperature of the cooling water of the diesel engine 2 is, for example, 20 ° C. or higher, preferably 30 ° C. or higher, for example, 80 ° C. or lower, preferably 40 ° C. or lower.

  In particular, in an environment where the temperature of the cooling water is 30 to 40 ° C. (for example, when the diesel engine 2 is cooled), the viscosity of the engine oil is relatively high, and the fuel injection amount corresponding to the dilution amount of the engine oil is low. Since the difference increases, the engine oil dilution amount can be calculated from the fuel injection amount with higher accuracy.

6). Action / Effect According to such an oil dilution amount determination method, the engine oil dilution amount is calculated from the fuel injection amount using the correlation map between the fuel injection amount of the diesel engine 2 and the engine oil dilution amount. The engine oil dilution amount of the diesel engine 2 can be determined without using a sensor and during the operation of the diesel engine 2.

  Further, when a known oil level type oil sensor is used to determine the dilution amount of the engine oil, the volume of the engine oil is usually determined and the dilution amount is calculated by increasing or decreasing the volume. Therefore, if the amount of engine oil does not change from the beginning, the amount of engine oil dilution can be detected. However, for example, when engine oil is added and used, there is a problem that the amount of engine oil dilution cannot be accurately detected from the volume. In addition, the oil level type oil sensor normally needs to store a predetermined amount of engine oil in the oil pan 15, and if the initial oil amount is excessively small, the oil dilution amount may not be detected.

  On the other hand, in the oil dilution amount determination method described above, the engine oil dilution amount is calculated from the fuel injection amount. Therefore, even when the engine oil is added and used or when the initial oil amount is excessively small, the diesel engine 2 engine oil dilution amount can be determined.

  Next, although this invention is demonstrated based on a reference example, this invention is not limited by the following example.

Reference Example 1
Engine oils having a dilution rate of 0% (new oil), 12.2%, and 17.5% were prepared, and the following operations were performed using each engine oil.

  That is, a diesel engine equipped with a DPF unit was driven, and fuel injection was performed while maintaining the oil temperature and the coolant temperature at 30 ° C. The fuel injection amount was feedback controlled so that the engine speed was maintained at 975 rpm.

  Then, the fuel injection amount was measured, and a correlation map between the increase / decrease in the engine oil dilution amount (dilution ratio) and the increase / decrease in the fuel injection amount was created. The results are shown in Table 1.

  The obtained correlation map is shown in FIG.

1 Diesel engine system 2 Diesel engine

Claims (2)

An oil dilution amount determination method for determining an engine oil dilution amount in a diesel engine,
A map creation step of creating a correlation map between the fuel injection amount of the diesel engine and the engine oil dilution amount;
A driving process for driving the diesel engine;
A control step of feedback-controlling the fuel injection amount so that the rotational speed of the diesel engine becomes a predetermined value; and
An oil dilution amount determination method comprising: a calculation step of calculating the engine oil dilution amount from the fuel injection amount based on the correlation map. Furthermore, after the map creation process,
2. The oil dilution amount according to claim 1, further comprising a map adjustment step of adjusting the correlation map by measuring the fuel injection amount when the diesel engine is driven for the first time after changing the engine oil. Judgment method.

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