JP2024020884A - Dilution determination device for lubricant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the accuracy of determining whether or not water exceeding a determination value is mixed in lubricant.

SOLUTION: A dilution determination device for lubricant executes: a process (step S30) of calculating a mixed water amount D, which is an amount of water mixed into lubricant per unit time in a current operating state of an internal combustion engine, during a period when specific conditions that a lubricant temperature L is less than a specified oil temperature LK (step S20: YES) and an outside temperature is less than a specified temperature are satisfied; a process (step S40) of calculating an integrated mixing value DA, which is an integrated value of the mixed water amount D during the period in which the specific conditions are satisfied, by integrating the mixed water amount D; and a process (step S50) of determining whether or not water equal to or larger than a determination value DK is mixed into the lubricant based on the integrated mixing value DA.

SELECTED DRAWING: Figure 3

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a lubricating oil dilution determination device.

Patent Document 1 discloses an internal combustion engine and a controller that determines whether or not lubricating oil in the internal combustion engine is diluted. The internal combustion engine has an oil pan and an oil pressure sensor. The oil pan stores lubricating oil for lubricating various parts of the internal combustion engine. The oil pressure sensor detects the oil pressure of lubricating oil flowing within the internal combustion engine.

In the internal combustion engine, fuel reaches the oil pan through the gap between the cylinder wall and the piston. When fuel mixes with lubricating oil, it dilutes the lubricating oil. In this case, the oil pressure detected by the oil pressure sensor decreases. The controller determines whether or not fuel is diluted in the lubricating oil based on the detected value of the oil pressure sensor.

Japanese Patent Application Publication No. 2004-293394

When fuel burns in the cylinder, water vapor generated as the fuel burns can reach the crankcase through the gap between the cylinder wall and the piston. At this time, if the wall surface of the crankcase is in a cold state, such as immediately after a cold start of the internal combustion engine, the water vapor that reaches the crankcase may condense on the wall surface of the crankcase and become water droplets. These water droplets can then get mixed into the lubricating oil in the oil pan. In order to determine whether or not water is mixed into the lubricating oil, it is conceivable to use oil pressure as an index as in Patent Document 1. However, the oil pressure varies depending on the operating state of the internal combustion engine. Therefore, it is not always possible to accurately determine that the lubricating oil has been diluted with water simply based on the oil pressure.

A lubricating oil dilution determining device for solving the above problems includes a cylinder which is a space in which fuel is combusted, a crankcase whose inside communicates with the cylinder, and a crankcase which communicates with the crankcase and stores lubricating oil. An oil temperature calculation process that calculates the temperature of the lubricating oil based on the operating state of the internal combustion engine, for an engine system that has an internal combustion engine that has an oil pan and an outside temperature sensor that detects outside temperature. and, when the specific conditions are that the temperature of the lubricating oil is less than a predetermined specified oil temperature and the outside temperature is less than a predetermined specified temperature, a period during which the specific conditions are satisfied. a mixed water amount calculation process that calculates a mixed water amount, which is the amount of water mixed into the lubricating oil per unit time in the current operating state of the internal combustion engine; and a mixed water amount calculation process that calculates the mixed water amount calculated in the mixed water amount calculation process. By doing so, an integration process is performed to calculate the integrated value of the amount of mixed water during the period when the specific condition is satisfied, and based on the integrated value, water exceeding a predetermined judgment value is mixed into the lubricating oil. A determination process is executed to determine whether or not the

When an internal combustion engine is started when the outside temperature is low and the crankcase wall is cold, water vapor generated as fuel burns can condense on the crankcase wall and become water droplets. These water droplets can then get mixed into the lubricating oil. Further, when the temperature of the lubricating oil is low, water mixed in the lubricating oil can remain in the lubricating oil without evaporating. Since there is a relationship between the outside temperature, the temperature of the lubricating oil, and the water mixed in the lubricating oil, when an internal combustion engine is operated under certain conditions, the amount of water contained in the lubricating oil will increase. It is likely to increase. Therefore, in the above configuration, the amount of mixed water and its integrated value are calculated in accordance with the operating state of the internal combustion engine for a period in which the specific condition is satisfied. By actually calculating the amount of mixed water and its integrated value, the amount of water contained in the lubricating oil can be accurately determined. By doing so, it is possible to improve the accuracy of determining whether or not water exceeding the determination value is mixed in the lubricating oil.

FIG. 1 is a schematic configuration diagram of a vehicle. FIG. 2 is a schematic diagram of the internal combustion engine. FIG. 3 is a flowchart showing the processing procedure of the diagnostic process. FIG. 4 is a time chart showing an example of changes in the integrated value of contamination.

Hereinafter, one embodiment of a lubricating oil dilution determination device will be described with reference to the drawings.
<Overall configuration of vehicle>
As shown in FIG. 1, vehicle 90 includes internal combustion engine 10, clutch 81, motor generator 82, transmission unit 80, hydraulic mechanism 86, differential 71, plural drive wheels 72, inverter 78, and battery 79.

Internal combustion engine 10 is a driving source for vehicle 90 . Details of the internal combustion engine 10 will be described later. Internal combustion engine 10 has a crankshaft 14 .
Motor generator 82 is a drive source for vehicle 90. Motor generator 82 has the functions of both an electric motor and a generator. Motor generator 82 has a stator 82C, a rotor 82B, and a rotating shaft 82A. Rotor 82B is rotatable relative to stator 82C. The rotating shaft 82A rotates together with the rotor 82B. Motor generator 82 is electrically connected to battery 79 via inverter 78 . Battery 79 transfers power to and from motor generator 82 . The inverter 78 converts direct current to alternating current.

Clutch 81 is interposed between internal combustion engine 10 and motor generator 82 . The clutch 81 is operated by hydraulic pressure from the hydraulic mechanism 86 to switch between a connected and disconnected state. When supplied with hydraulic pressure, the clutch 81 enters a connected state in which the crankshaft 14 and the rotating shaft 82A of the motor generator 82 are connected. When the supply of hydraulic pressure is stopped, the clutch 81 enters a disconnected state in which the crankshaft 14 and the rotating shaft 82A are separated.

The transmission unit 80 includes a torque converter 83 and an automatic transmission 85. Torque converter 83 includes a pump impeller 83A, a turbine liner 83B, and a lockup clutch 84. Torque converter 83 is a fluid coupling having a torque amplification function. Pump impeller 83A rotates integrally with rotation shaft 82A of motor generator 82. The turbine liner 83B rotates integrally with the input shaft of the automatic transmission 85. The lock-up clutch 84 receives oil pressure from the hydraulic mechanism 86 and directly connects the pump impeller 83A and the turbine liner 83B.

The automatic transmission 85 is a stepped transmission in which the gear ratio changes in multiple stages by changing gears. An output shaft of the automatic transmission 85 is connected to left and right drive wheels 72 via a differential 71. The differential 71 allows a difference in rotational speed to occur between the left and right drive wheels 72. Note that the clutch 81, motor generator 82, and transmission unit 80 are housed in a single case. In other words, the clutch 81, motor generator 82, and transmission unit 80 are configured as an integrated hybrid transaxle.

Vehicle 90 has a notification lamp 57. The notification lamp 57 is located inside the cabin of the vehicle 90. The notification lamp 57 lights up in response to a lighting signal B from the control device 100, which will be described later. Vehicle 90 includes a vehicle speed sensor 58, an accelerator sensor 59, and a power switch 60. Vehicle speed sensor 58 detects the traveling speed of vehicle 90 as vehicle speed SP. The accelerator sensor 59 detects the amount of depression of the accelerator pedal in the vehicle 90 as the accelerator operation amount ACC. Power switch 60 is a system activation switch for vehicle 90. Each of the above-mentioned sensors repeatedly transmits a signal corresponding to the information detected by itself to the control device 100 described below. Further, the power switch 60 transmits a signal U according to the driver's operation to the control device 100, which will be described later.

<Schematic configuration of internal combustion engine>
As shown in FIG. 2, the internal combustion engine 10 includes a cylinder block 26, a crankcase 29, an oil pan 27, and a crank chamber 28. Further, the internal combustion engine 10 includes a plurality of cylinders 11, a plurality of pistons 12, a plurality of connecting rods 13, and the crankshaft 14. The number of cylinders 11 is four. Note that in FIG. 2, only one of the plurality of cylinders 11 is shown. The same applies to the piston 12 and the connecting rod 13. A piston 12 and a connecting rod 13 are provided for each cylinder 11.

The cylinder 11 is a space defined by a cylinder block 26. The cylinder 11 is a space in which a mixture of fuel and intake air is combusted. Piston 12 is located in cylinder 11. The piston 12 reciprocates. The piston 12 is connected to a crankshaft 14 via a connecting rod 13. The crankshaft 14 rotates in accordance with the reciprocating movement of the piston 12. The crankshaft 14 is located in a crank chamber 28. The crank chamber 28 is a space defined by a crankcase 29 located below the cylinder block 26 and an oil pan 27 located below the crankcase 29. That is, the inside of the crankcase 29 and the inside of the oil pan 27 are in communication with each other. The crankcase 29 has a frame shape. The oil pan 27 is box-shaped. Lubricating oil for lubricating various parts of the internal combustion engine 10 is collected at the bottom of the oil pan 27 . The lubricating oil used is one that exhibits high fluidity even in an environment of 0°C or lower. The inside of the crankcase 29 and the inside of the oil pan 27, ie, the crank chamber 28, communicate with each cylinder 11. Although not shown, an oil passage extends from the oil pan 27 for supplying lubricating oil to parts that require lubrication.

Internal combustion engine 10 has a water jacket 25. In addition, in FIG. 2, the water jacket 25 is shown by a thick solid line for convenience. The water jacket 25 is a passage defined by the cylinder block 26 through which cooling water flows. The water jacket 25 is located around the plurality of cylinders 11. The circulation of the cooling water is driven by, for example, an electric pump. Note that the cooling water is, for example, LLC (Long Life Coolant), and is prevented from freezing.

Internal combustion engine 10 has a plurality of spark plugs 19. Note that in FIG. 2, only one of the plurality of spark plugs 19 is shown. A spark plug 19 is provided for each cylinder 11. The spark plug 19 ignites the mixture of intake air and fuel in the cylinder 11 .

Internal combustion engine 10 has a plurality of fuel injection valves 17. Note that in FIG. 2, only one of the plurality of fuel injection valves 17 is shown. A fuel injection valve 17 is provided for each cylinder 11. The fuel injection valve 17 supplies fuel directly to the cylinder 11 without passing through the intake passage 15, which will be described later.

Internal combustion engine 10 has an intake passage 15, a throttle valve 16, and an exhaust passage 21. The intake passage 15 is connected to each cylinder 11. Intake air from the outside flows through the intake passage 15 . The throttle valve 16 is located in the middle of the intake passage 15. The throttle valve 16 adjusts the amount of intake air (hereinafter referred to as intake air amount) GA. The exhaust passage 21 is connected to each cylinder 11. Exhaust gas from each cylinder 11 flows through the exhaust passage 21 .

Internal combustion engine 10 has a blow-by gas recirculation mechanism. The blow-by gas recirculation mechanism is a mechanism for recirculating blow-by gas, which is gas that has leaked into the crank chamber 28 through the gap between the piston 12 and the wall surface that partitions the cylinders 11 in the cylinder block 26, to the intake passage 15. . The blowby gas recirculation mechanism includes a first blowby gas passage 31, a second blowby gas passage 32, and a PCV valve 33. The first blow-by gas passage 31 communicates the crank chamber 28 with a portion of the intake passage 15 on the upstream side when viewed from the throttle valve 16 . The second blow-by gas passage 32 communicates the crank chamber 28 with a portion of the intake passage 15 on the downstream side when viewed from the throttle valve 16 . The PCV valve 33 is located in the middle of the second blow-by gas passage 32. The PCV valve 33 opens when the pressure in the downstream portion of the intake passage 15 when viewed from the throttle valve 16 becomes lower than a specified value. At this time, the second blowby gas passage 32 allows blowby gas to flow from the crank chamber 28 to the intake passage 15. Note that when the blow-by gas flows through the second blow-by gas passage 32, the intake air flows from the intake passage 15 to the crank chamber 28 in the first blow-by gas passage 31.

The internal combustion engine 10 includes a crank position sensor 40, an air flow meter 41, an intake temperature sensor 42, a water temperature sensor 44, and an oil temperature sensor 45. The crank position sensor 40 detects the rotational position CR of the crankshaft 14. Air flow meter 41 detects intake air amount GA. The intake air temperature sensor 42 detects the temperature (hereinafter referred to as intake air temperature) of the intake air flowing in the downstream portion of the intake passage 15 when viewed from the throttle valve 16 . Note that the intake air temperature P generally matches the atmospheric temperature, that is, the outside air temperature. The water temperature sensor 44 detects the temperature of the cooling water (hereinafter referred to as cooling water temperature) W at the outlet of the water jacket 25. The oil temperature sensor 45 detects the temperature L of lubricating oil collected in the oil pan 27. Each of these sensors repeatedly transmits a signal corresponding to the information detected by itself to the control device 100 described below.

In the above configuration, the motor generator 82, the internal combustion engine 10, and the intake temperature sensor 42 as an outside temperature sensor constitute an engine system. Note that in this embodiment, the internal combustion engine 10 includes an intake temperature sensor 42 as an outside temperature sensor.

<Schematic configuration of control device>
As shown in FIG. 1, vehicle 90 includes a control device 100. Control device 100 may be configured as one or more processors that execute various processes according to computer programs (software). Note that the control device 100 includes one or more dedicated hardware circuits such as an application specific integrated circuit (ASIC), or a circuit including a combination thereof, which executes at least some of the various types of processing. It may also be configured as The processor includes a CPU 111 and memories such as RAM and ROM 112. The memory stores program codes or instructions configured to cause the CPU 111 to perform processes. Memory or computer-readable media includes any available media that can be accessed by a general purpose or special purpose computer. Control device 100 includes electrically rewritable nonvolatile memory 113. The control device 100 performs various processes and controls described below by having the CPU 111 execute a program stored in the ROM 112.

Control device 100 repeatedly receives signals from various sensors of vehicle 90. Control device 100 also receives signal U from power switch 60. When control device 100 receives signal U corresponding to power switch 60 being turned on, control device 100 electrically connects battery 79 and motor generator 82 . By doing so, the control device 100 makes the vehicle 90 ready to travel. Hereinafter, the period from when the power switch 60 is turned on to when it is turned off next time will be referred to as "one trip." Note that the control device 100 can output the lighting signal B to the notification lamp 57.

Control device 100 executes drive control of vehicle 90 during one trip. In drive control, control device 100 selects either a hybrid mode or an electric mode as the drive mode of vehicle 90. Control device 100 then controls various parts of vehicle 90 according to the selected drive mode. In the electric mode, control device 100 stops internal combustion engine 10 and drives motor generator 82 . Furthermore, in the electric mode, the control device 100 puts the clutch 81 in a disengaged state. On the other hand, control device 100 drives both internal combustion engine 10 and motor generator 82 in the hybrid mode. Further, the control device 100 connects the clutch 81 in the hybrid mode. Note that in the hybrid mode, the control device 100 may cause the motor generator 82 to generate regenerative power using the power of the internal combustion engine 10. During one trip, the control device 100 selects an appropriate drive mode and switches the drive mode at any time according to the vehicle speed SP, accelerator operation amount ACC, and the like. For example, the control device 100 selects the hybrid mode when the required driving force ascertained from the vehicle speed SP and the accelerator operation amount ACC is large enough to operate the internal combustion engine 10 at a correspondingly high combustion efficiency, such as during normal driving. select. On the other hand, the control device 100 selects the electric mode when the vehicle 90 starts or stops. Furthermore, if an electric mode prohibition flag, which is set in a diagnostic process to be described later, is on, the control device 100 selects the hybrid mode instead of the electric mode. The prohibition flag is a flag indicating prohibition of electric mode. Note that the control device 100 sets a drive flag for identifying the currently selected drive mode. For example, the control device 100 sets the drive flag to "1" when the hybrid mode is selected, and sets the drive flag to "2" when the electric mode is selected.

When operating the internal combustion engine 10, the control device 100 controls the fuel injection of the fuel injection valve 17, the ignition timing of the spark plug 19, and the throttle valve 16 while taking into account the current engine speed NE and engine load factor of the internal combustion engine 10. Performs various controls such as opening degree adjustment. Through such control, the control device 100 causes the plurality of cylinders 11 to sequentially combust the air-fuel mixture. Note that the engine rotation speed NE is the rotation speed of the crankshaft 14. The engine rotational speed NE can be determined from the rotational position CR of the crankshaft 14 detected by the crank position sensor 40. The engine load factor is a value obtained by dividing the intake air amount GA flowing into one cylinder 11 in one combustion cycle by the reference intake air amount. The reference intake air amount changes depending on the engine rotation speed NE. The engine load factor can be determined from the engine rotational speed NE and the intake air amount GA detected by the air flow meter 41.

<Function as a lubricating oil dilution determination device>
If the soak period, which is the period from the end of one trip to the start of the next trip, is quite long, the temperature of the inner wall surface of the crankcase 29 (hereinafter simply referred to as the wall surface) will be approximately the same as the outside temperature. Become. Therefore, if the soak period is quite long and the outside temperature is low, the wall surface of the crankcase 29 will also be in a cold state. When the internal combustion engine 10 is started with the wall surface of the crankcase 29 cold, water vapor generated in response to combustion of fuel may condense on the wall surface of the crankcase 29 and become water droplets. These water droplets mix into the lubricating oil stored in the oil pan 27. When water mixes into lubricating oil, the lubricating oil becomes diluted. The control device 100 functions as a dilution determining device for an engine system that determines whether lubricating oil is diluted in response to water contamination as described above.

The control device 100 is capable of executing diagnostic processing for determining whether or not the lubricating oil is diluted. The control device 100 can execute oil temperature calculation processing as part of the diagnostic processing. In the oil temperature calculation process, the control device 100 calculates the current temperature L of the lubricating oil based on the operating state of the internal combustion engine 10. In this embodiment, the control device 100 converts the current value of the lubricating oil temperature L, which is one of the parameters representing the operating state of the internal combustion engine 10, into a detection signal of the oil temperature sensor 45 that detects the temperature L itself. Calculate based on The control device 100 essentially calculates the latest lubricating oil temperature L received from the oil temperature sensor 45 as the current lubricating oil temperature L as it is.

The control device 100 can execute a contamination amount calculation process as part of the diagnostic process. In the mixing amount calculation process, the control device 100 calculates the amount of water mixed into the lubricating oil per unit time in the current operating state of the internal combustion engine 10 during a period when the internal combustion engine 10 is operating and a specific condition is satisfied. Calculate the amount of Hereinafter, the amount of water mixed into the lubricating oil per unit time will be referred to as the mixed water amount D.

The above specific condition is that both of the following two items (A1) and (A2) are satisfied.
(A1) The outside temperature is less than the specified temperature PK.
(A2) The temperature L of the lubricating oil is less than the specified oil temperature LK.

The specified temperature PK will be explained. As mentioned above, if the soak period is quite long, the temperature of the wall surface of the crankcase 29 will be approximately the same as the outside air temperature. The specified temperature PK is the temperature of the wall surface of the crankcase 29 at which it is expected that condensation on the wall surface of the crankcase 29 and water contamination with the lubricating oil will increase considerably when the internal combustion engine 10 starts, and is determined by, for example, an experiment or simulation. predetermined. The specified temperature PK is, for example, -10°C. The control device 100 stores the specified temperature PK in advance. Note that the control device 100 of this embodiment treats the intake air temperature P as the outside air temperature. Therefore, the control device 100 essentially determines whether the condition that the intake temperature P is less than the specified temperature PK is satisfied.

The specified oil temperature LK will be explained. Suppose that the temperature L of the lubricating oil is gradually raised while water is mixed in the lubricating oil. When the temperature L of the lubricating oil becomes close to the boiling point of water, the amount of water evaporated from the lubricating oil begins to increase rapidly. The temperature at which the amount of water evaporation from the lubricating oil begins to rapidly increase is called the rapid increase temperature. The rapid temperature increase is, for example, 80°C. The sudden temperature increase can be determined, for example, by experiment or simulation. The above specified oil temperature LK is predetermined as a rapid increase temperature. The control device 100 stores the specified oil temperature LK in advance.

The control device 100 stores a first map in advance as information for calculating the amount D of mixed water. The first map shows the relationship between the amount of water newly mixed into the lubricating oil within a unit time (hereinafter referred to as new water amount) and the cooling water temperature W, which is a parameter that reflects the temperature of the wall surface of the crankcase 29. It is expressed. As described above, when the temperature of the wall surface of the crankcase 29 is low, water is likely to be generated in the crankcase 29, and the amount of water that gets mixed into the lubricating oil in the oil pan 27 also increases. As the temperature of the wall surface of the crankcase 29 increases, the amount of water mixed into the lubricating oil decreases. Reflecting this relationship, in the first map, the lower the cooling water temperature W, the greater the amount of new water. Particularly in a temperature range where the cooling water temperature W is 0° C. or lower, the amount of new water is considerably large. Further, even if the cooling water temperature W is in a temperature range of 0° C. or higher, in a relatively low temperature range of, for example, about 20° C. or lower, the amount of new water is correspondingly large. The first map is created based on, for example, experiments or simulations on the premise that the fuel injection amount during operation of the internal combustion engine 10 is a certain normal injection amount. The normal injection amount is a fuel injection amount that can be considered to be somewhat common during operation of the internal combustion engine 10 and is determined, for example, from experiments or simulations. Note that, like the lubricating oil temperature L, the cooling water temperature W is a parameter representing the operating state of the internal combustion engine 10.

The control device 100 stores a second map in advance as information for calculating the mixed water amount D. The second map represents the relationship between the amount of evaporated water, which is the amount of water that evaporates from the lubricating oil within a unit time, and the temperature L of the lubricating oil. Note that the unit time that defines the amount of evaporated water in the second map and the unit time that defines the new amount of water in the first map are the same length. The relationship between the amount of evaporated water and the lubricating oil temperature L in the second map reflects the water evaporation characteristics described in relation to the specified oil temperature LK. That is, in the second map, the amount of evaporated water basically increases as the temperature L of the lubricating oil increases. The amount of evaporated water in a temperature range where the lubricating oil temperature L is lower than the rapid increase temperature is extremely small. On the other hand, in a temperature range where the temperature L of the lubricating oil is higher than the rapidly increasing temperature, the amount of evaporated water rapidly increases as the temperature L of the lubricating oil increases. The second map is created based on, for example, experiment or simulation.

In the mixed amount calculation process, the control device 100 calculates the current mixed water amount D by subtracting the evaporated water amount from the new water amount. In other words, the amount of mixed water D is the net amount of water mixed into the lubricating oil, which is obtained by subtracting the amount of water that evaporates from the lubricating oil within the unit time from the amount of water newly mixed into the lubricating oil within the unit time. be. Here, in relation to the specific condition item (A2), the amount of mixed water D is calculated in the operating state of the internal combustion engine 10 in which the temperature L of the lubricating oil is lower than the sudden increase temperature. In the operating state of the internal combustion engine 10 in which the temperature L of the lubricating oil is lower than the sudden increase temperature, the amount of evaporated water is small, so basically, the amount of mixed water D takes a value that reflects the new amount of water. In an operating state of the internal combustion engine 10 in which the lubricating oil temperature L and the cooling water temperature W are below 0° C., the mixed water amount D becomes considerably large. As the temperature L of the lubricating oil and the temperature W of the cooling water increase, the amount of mixed water D decreases. In a temperature environment where neither dew condensation nor evaporation occurs easily, the amount of mixed water D is approximately zero. Note that the lubricating oil temperature L and the cooling water temperature W basically change in conjunction with the degree of warming up of the internal combustion engine 10. The lubricating oil temperature L and the cooling water temperature W increase as the internal combustion engine 10 warms up.

The control device 100 can execute integration processing as part of the diagnostic processing. In the integration process, the control device 100 integrates the amount of mixed water D calculated in the mixed amount calculation process, thereby obtaining an integrated value of the amount of mixed water D during a period when the internal combustion engine 10 is operating and a specific condition is satisfied. (Hereinafter, referred to as the integrated value of contamination.) Calculate DA. In addition, in the integration process, when the lubricating oil temperature L increases to the specified oil temperature LK while the internal combustion engine 10 is operating, the control device 100 resets the contamination integration value DA to zero. This depends on the following considerations. That is, when the temperature L of the lubricating oil increases to the specified oil temperature LK, there is almost no new water mixed into the lubricating oil, while the amount of water evaporating from the lubricating oil rapidly increases. As a result, water contained in the lubricating oil quickly disappears. Note that the water evaporated from the lubricating oil reaches the intake passage 15 together with the blow-by gas through the second blow-by gas passage 32.

In addition, in the integration process, if the internal combustion engine 10 ends operation without the lubricating oil temperature L reaching the specified oil temperature LK, the control device 100 uses the contamination integration value DA at that point as the ending integration value DAx. It is stored in the non-volatile memory 113. Then, when the internal combustion engine 10 is started and operated next time, the control device 100 updates the contamination integrated value DA using the ending integrated value DAx as an initial value. Note that the situation in which the internal combustion engine 10 stops operating is either a situation in which the drive mode switches to electric mode in the middle of one trip, or a situation in which one trip ends as the power switch 60 is turned off. That's it.

The control device 100 can execute a determination process as part of the diagnostic process. In the determination process, the control device 100 determines whether water in an amount equal to or greater than the determination value DK is currently mixed into the lubricating oil based on the integrated mixing value DA. The determination value DK will be explained. Here, it is assumed that the internal combustion engine 10 is stopped while the amount of water contained in the lubricating oil is relatively large, and the internal combustion engine 10 is exposed to a low-temperature environment. Suppose that the water in the lubricating oil freezes. When the amount of water contained in the lubricating oil is relatively large and the water freezes, relatively large chunks of ice form within the lubricating oil. Such relatively large chunks of ice may block the oil passage when the internal combustion engine 10 is started next time. The determination value DK is predetermined, for example, by experiment or simulation, as a value for the amount of water contained in the lubricating oil that may cause the oil passage to become clogged due to freezing. The determination value DK is, for example, a value of 20% of the total amount of lubricating oil. The control device 100 stores the determination value DK in advance. Note that the fact that the control device 100 makes an affirmative determination in the determination process corresponds to the control device 100 determining that dilution of the lubricating oil has occurred.

The control device 100 can execute countermeasure processing as part of the diagnostic processing. When the control device 100 makes an affirmative determination in the determination process, it performs a countermeasure process. In the countermeasure process, the control device 100 prohibits selection of the electric mode in drive control until the lubricating oil temperature L increases to the specified oil temperature LK. Further, the control device 100 turns on the notification lamp 57 while prohibiting selection of the electric mode.

<Specific processing procedure of diagnostic processing>
During one trip, when the internal combustion engine 10 is started, that is, when the drive mode is switched to the hybrid mode by drive control, the control device 100 determines that the latest intake temperature P received from the intake temperature sensor 42 is less than the specified temperature PK. Starts diagnostic processing under the condition. Note that starting the internal combustion engine 10 means starting combustion of fuel by starting control of ignition timing and fuel injection. Here, in consideration of the specific processing contents of the diagnostic processing that will be explained later, the period required from the start to the end of one diagnostic processing will vary depending on the situation such as the timing at which the internal combustion engine 10 is stopped. The longest time is, for example, about 10 to 20 minutes. The outside temperature does not change much on this time scale. Therefore, the outside temperature during execution of the diagnostic process can be considered to be approximately constant. That is, the outside temperature during execution of the diagnostic process is maintained below the specified temperature PK.

As shown in FIG. 3, when the control device 100 starts the diagnostic process, it first executes the process of step S10. In step S10, control device 100 determines whether or not internal combustion engine 10 is continuing to operate. The control device 100 makes the determination in step S10 based on the drive mode selection status in drive control and the operation status of the power switch 60. If the hybrid mode is selected in the drive control, the control device 100 determines YES in step S10. In this case, the control device 100 advances the process to step S20. Note that the control device 100 may refer to the drive flag in order to grasp the selection status of the drive mode.

In step S20, the control device 100 determines whether the current lubricating oil temperature L is less than the specified oil temperature LK. As specific processing in step S20, the control device 100 first calculates the latest lubricating oil temperature L received from the oil temperature sensor 45 as the current lubricating oil temperature L. This process is an oil temperature calculation process. After this, the control device 100 compares the current lubricating oil temperature L and the specified oil temperature LK. Then, when the current lubricating oil temperature L is less than the specified oil temperature LK (step S20: YES), the control device 100 advances the process to step S30.

In step S30, the control device 100 calculates the mixed water amount D. When calculating the mixed water amount D, the control device 100 first calculates the new water amount. Specifically, the control device 100 refers to the first map. Then, the control device 100 calculates the new water amount corresponding to the latest cooling water temperature W received from the water temperature sensor 44 as the current new water amount in the first map. After this, the control device 100 calculates the amount of evaporated water. Specifically, the control device 100 refers to the second map. Then, in the second map, the control device 100 calculates the amount of evaporated water corresponding to the current temperature L of the lubricating oil calculated in step S20 as the current amount of evaporated water. Thereafter, the control device 100 calculates a value obtained by subtracting the amount of evaporated water from the new amount of water as the amount of mixed water D. After this, the control device 100 advances the process to step S40. Note that the process in step S30 is a mixing amount calculation process.

In step S40, the control device 100 updates the contamination integrated value DA. Specifically, the control device 100 adds the mixed water amount D calculated in step S30 to the previous value DAn of the mixed integrated value DA. Then, the control device 100 sets the obtained value as the latest contamination integrated value DA. Note that when the control device 100 executes step S40 for the first time after starting the diagnostic process, the end-time integrated value DAx stored in the nonvolatile memory 113 in the previous diagnostic process is used as the previous value DAn. The process of storing the end-time integrated value DAx in the nonvolatile memory 113 will be explained in step S90, which will be described later. On the other hand, if this step S40 is executed for the second time or later after the start of the diagnostic process, the control device 100 employs the contamination integrated value DA calculated in the previous step S40 as the previous value DAn. After updating the contamination integrated value DA, the control device 100 advances the process to step S50. Note that the process in step S40 is an integration process.

In step S50, the control device 100 determines whether the integrated contamination value DA calculated in step S40 is greater than or equal to the determination value DK. When the contamination integrated value DA is less than the determination value DK (step S50: NO), the control device 100 returns to the process of step S10. At this time, it is assumed that the determination in step S10 is YES again, and the determination in step S20 is also YES. In this case, the control device 100 executes the processes from step S30 to step S50 again. The control device 100 repeats the processing from step S10 to step S50 while the situation in which the determinations in step S10 and step S20 are YES and the determination in step S50 is NO continues. Then, when the contamination integrated value DA becomes equal to or greater than the determination value DK (step S50: YES), the control device 100 advances the process to step S60. Note that the execution interval of step S30 while repeating the processes of steps S10 to S50 as described above is the unit time in which the new water amount is defined in the first map, and the evaporated water amount is defined in the second map. It is set to the same length as the unit time. The unit time is, for example, 1 second.

In step S60, the control device 100 determines that water equal to or greater than the determination value DK is mixed in the lubricating oil. After this, the control device 100 advances the process to step S70. Note that the processes in step S60 and step S70 are determination processes.

In step S70, the control device 100 executes a countermeasure process. Specifically, control device 100 switches the electric mode prohibition flag from off to on. Further, the control device 100 lights up the notification lamp 57. Thereafter, the control device 100 monitors the transition of the lubricating oil temperature L received from the oil temperature sensor 45. Then, the control device 100 waits until the lubricating oil temperature L increases to the specified oil temperature LK. Note that since the electric mode prohibition flag is on, the control device 100 continues to select the hybrid mode in drive control. That is, the control device 100 causes the internal combustion engine 10 to continue operating. As a result, the warm-up of the internal combustion engine 10 progresses, and the temperature L of the lubricating oil increases. When the lubricating oil temperature L increases to the specified oil temperature LK, the control device 100 switches the electric mode prohibition flag from on to off. Further, the control device 100 turns off the notification lamp 57. After this, the control device 100 advances the process to step S80.

In step S80, the control device 100 resets the contamination integrated value DA to zero. After this, the control device 100 advances the process to step S90. In step S90, the control device 100 stores the latest contamination integrated value DA in the nonvolatile memory 113 as the end integrated value DAx. After this, the control device 100 ends the series of diagnostic processing. Note that the processes in step S80 and step S90 are part of the integration process.

Now, in step S20, if the current lubricating oil temperature L is equal to or higher than the specified oil temperature LK (step S20: NO), the control device 100 advances the process to step S80. That is, for example, when the lubricating oil temperature L increases to the specified oil temperature LK while repeating the processing of steps S10 to S50, the control device 100 advances the processing to step S80. Then, the control device 100 resets the contamination integrated value DA to zero.

Further, in step S10, the control device 100 determines that the operation of the internal combustion engine 10 has ended when the drive mode is switched to the electric mode in the drive control, or when the power switch 60 is turned off (step S10: NO). In this case, the control device 100 advances the process to step S90. For example, if the control device 100 switches the drive mode or operates the power switch 60 while repeating the processing from step S10 to step S50, the control device 100 advances the processing to step S90. Then, the control device 100 stores the latest contamination integration value DA in the nonvolatile memory 113 in step S90.

Note that regarding step S70, the power switch 60 may be turned off during execution of the countermeasure process. In this case, the control device 100 ends the diagnostic process at that point. However, before ending the diagnostic process, the control device 100 stores the latest contamination integration value DA at that time in the nonvolatile memory 113 as the completion integration value DAx. After that, the control device 100 ends the diagnostic process. If this is done, the next time the diagnostic process is executed, the process will proceed as follows. That is, when the control device 100 starts the diagnostic process, the determinations in steps S10, S20, and S50 are inevitably YES, so the process proceeds to step S70. Therefore, the control device 100 restarts the handling process.

<Action of the embodiment>
It is assumed that the vehicle 90 has been exposed to an environment where the outside temperature is lower than the specified temperature PK for a long period of time. Assume that the entire internal combustion engine 10 has cooled considerably, and the temperature L of the lubricating oil and the wall surface of the crankcase 29 have reached a temperature close to the outside temperature. Assume that the power switch 60 is turned on at time T1 under this situation. Assume that the control device 100 selects the hybrid mode and operates the internal combustion engine 10. Then, the control device 100 starts diagnostic processing. At this time, since the temperature L of the lubricating oil is low (step S20: YES), the control device 100 starts integrating the contamination integrated value DA (step S30, step S40). That is, as shown in FIG. 4, after time T1, the control device 100 sequentially updates the contamination integrated value DA by repeating the processing of steps S10 to S50. During this time, the temperature L of the lubricating oil also gradually increases as the internal combustion engine 10 warms up.

After this, as shown in FIG. 4, before the contamination cumulative value DA reaches the determination value DK (step S50: NO) and before the lubricating oil temperature L reaches the specified oil temperature LK (step S20: YES), and the power switch 60 is turned off at time T2 (step S10: NO). In this case, the control device 100 stores the contamination integrated value DA calculated last before the power switch 60 is turned off as the end integrated value DAx in the nonvolatile memory 113 (step S90). Then, the control device 100 temporarily ends the diagnostic process.

It is assumed that after this, the vehicle 90 is again exposed to a low temperature environment for a long period of time. Assume that the entire internal combustion engine 10 has cooled considerably, and the temperature L of the lubricating oil and the temperature of the wall surface of the crankcase 29 have returned to a temperature close to the outside temperature. Assume that under these circumstances, time T3 has arrived as shown in FIG. It is assumed that the power switch 60 is turned on at time T3. Assume that the control device 100 selects the hybrid mode and operates the internal combustion engine 10. Then, similarly to the above, the control device 100 starts the diagnostic process and resumes updating the contamination integrated value DA (step S30, step S40). When the control device 100 restarts updating the contamination integrated value DA, the control device 100 uses the ending integrated value DAx stored at time T2 as an initial value. Then, the control device 100 sequentially updates the contamination integrated value DA by repeating the processing from step S10 to step S50 as described above.

After this, as in the case of time T2, before the contamination cumulative value DA reaches the judgment value DK (step S50: NO) and before the lubricating oil temperature L reaches the specified oil temperature LK (step S20: YES). Assume that the power switch 60 is turned off at time T4 (step S10: NO). It is assumed that the power switch 60 is turned on at time T5 after the vehicle 90 has been exposed to a low-temperature environment for a long time again, and the operation of the internal combustion engine 10 is started. Then, the control device 100 resumes updating the contamination accumulation value DA using the contamination accumulation value DA at time T4 as an initial value, and sequentially updates the contamination accumulation value DA. After this, it is assumed that the contamination integrated value DA reaches the determination value DK at time T6 (step S50: YES). Then, the control device 100 determines that water equal to or greater than the determination value DK has mixed into the lubricating oil (step S60). Then, the control device 100 prohibits switching to the electric mode and turns on the notification lamp 57 (step S70). Thereafter, when the lubricating oil temperature L increases to the specified oil temperature LK, the control device 100 cancels the inhibition of switching to the electric mode and turns off the notification lamp 57. After this, the control device 100 resets the contamination integrated value DA to zero (step S80). The control device 100 then ends the diagnostic process.

As shown in the above example, it is often necessary to execute the diagnostic process multiple times before obtaining the determination result that the lubricating oil is contaminated with water equal to or higher than the determination value DK. In addition, although FIG. 4 shows an example where the number of trips for the contamination cumulative value DA to reach the judgment value DK is three, the number of trips for the contamination cumulative value DA to reach the determination value DK varies depending on the situation. . In addition, in FIG. 4, the rate of increase in the cumulative contamination value DA is kept constant when the cumulative contamination value DA is updated, but this is an example to easily explain the transition of the cumulative contamination value DA. , does not necessarily match the actual one.

Unlike the example in FIG. 4, during the update of the integrated contamination value DA, that is, while repeating the processing from step S10 to step S50, the internal combustion engine 10 is It may be stopped (step S10: NO). In this case, as in the above example, the control device 100 stores the contamination integrated value DA at the time when the internal combustion engine 10 is stopped in the nonvolatile memory 113 as the end integrated value DAx (step S90). Then, the next time the internal combustion engine 10 is started, the control device 100 resumes updating the contamination integrated value DA using the ending integrated value DAx as the initial value.

Further, unlike the example in FIG. 4, the lubricating oil temperature L may reach the specified oil temperature LK during the update of the contamination integrated value DA (step S20: NO). In this case, the control device 100 resets the contamination integrated value DA to zero at that point (step S80). Then, the control device 100 stores zero in the nonvolatile memory 113 as the end-time integrated value DAx (step S90). In this case, the next time the internal combustion engine 10 is started, the control device 100 updates the contamination integrated value DA with zero, which is the ending integrated value DAx, as an initial value, if the specific condition is satisfied.

<Effects of embodiment>
(1) Under conditions where specific conditions are met, both the wall surface of the crankcase 29 and the lubricating oil in the oil pan 27 are cold. Therefore, when the internal combustion engine 10 is operated under certain conditions, water droplets are likely to be generated in the crankcase 29, and the water that has reached the oil pan 27 from the wall of the crankcase 29 may enter the lubricating oil. continue to stay. Therefore, the amount of water contained in the lubricating oil increases. Therefore, in the above configuration, the mixed water amount D and the mixed water integrated value DA as the integrated value are calculated in accordance with the operating state of the internal combustion engine 10 for a period in which the specific condition is satisfied. By calculating the amount of mixed water D and the integrated value DA of mixed water, the amount of water contained in the lubricating oil can be accurately grasped. By doing so, it is possible to accurately determine whether or not water exceeding the determination value DK is mixed in the lubricating oil.

(2) If the operation of the internal combustion engine 10 ends before the temperature L of the lubricating oil increases during operation of the internal combustion engine 10, the water mixed in the lubricating oil will still remain in the lubricating oil even when the internal combustion engine 10 starts next time. remains mixed in. Therefore, in the above configuration, if the previous operation of the internal combustion engine 10 ends without the lubricating oil temperature L increasing to the specified oil temperature LK, the contamination cumulative value DA during the previous operation of the internal combustion engine 10 is used as the contamination cumulative value DA for the next internal combustion engine Set it as the initial value of the contamination cumulative value DA during operation in step 10. Therefore, even under conditions where the internal combustion engine 10 is repeatedly operated in a relatively short period of time where the temperature L of the lubricating oil does not rise, it is possible to accurately determine whether or not the lubricating oil contains water exceeding the judgment value DK. Can be judged.

(3) As the temperature of the wall surface of the crankcase 29 decreases, the amount of water generated in the crankcase 29 increases. Furthermore, although the amount of water evaporating from the lubricating oil is small when the temperature L of the lubricating oil is lower than the sudden rise temperature, the amount of water evaporating from the lubricating oil gradually increases as the temperature L of the lubricating oil increases. Become. In this embodiment, by using the first map and the second map, water is mixed while taking into account the behavior of water as described above depending on the temperature of the wall surface of the crankcase 29 and the temperature L of the lubricating oil. The amount of water D is calculated. Therefore, it is possible to accurately calculate the mixed water amount D and, by extension, the mixed water integrated value DA.

(4) In the present embodiment, when it is determined that there is water mixed in at a level equal to or higher than the determination value DK, switching the drive mode of the vehicle 90 to the electric mode is prohibited. This facilitates warming up of the internal combustion engine 10 and allows water to quickly evaporate from the lubricating oil. Therefore, it is possible to prevent water mixed into the lubricating oil from clogging the oil passage.

<Example of change>
Note that the above embodiment can be modified and implemented as follows. The embodiments and the following modification examples can be implemented in combination with each other within a technically consistent range.

- The map is not limited to a table or a graph, but may also be a mathematical formula.
- The method of determining whether or not the internal combustion engine 10 is continuing to operate in step S10 is not limited to the example of the above embodiment. For example, the above judgment may be made using the engine rotational speed NE as an index. If the engine rotation speed NE is greater than zero, it may be determined that the internal combustion engine 10 is continuing to operate, and if the engine rotation speed NE is zero, it may be determined that the internal combustion engine 10 has stopped. Any method may be used as long as it can appropriately determine whether or not the internal combustion engine 10 is continuing to operate.

- The content of the countermeasure processing is not limited to the example of the above embodiment. Other treatments may be performed instead of or in addition to the aspects adopted in the above embodiments. For example, the ignition timing of the spark plug 19 in the internal combustion engine 10 may be retarded, or the engine rotational speed NE during idling may be made higher than normal. Idle operation means operating the internal combustion engine 10 at the minimum rotational speed of the crankshaft 14 at which the internal combustion engine 10 can operate independently. The countermeasure processing may be any kind of countermeasure as long as it takes some kind of countermeasure to the determination that water of the determination value DK or more has mixed into the lubricating oil. As a countermeasure, information indicating that water equal to or higher than the determination value DK has mixed into the lubricating oil may be stored in the nonvolatile memory 113. In this case, for example, when inspecting the vehicle 90, the information can be read out and utilized as information when maintaining the vehicle 90.

- The content of the oil temperature calculation process is not limited to the example of the above embodiment. That is, the current method of calculating the lubricating oil temperature L is not limited to the example of the above embodiment. For example, the lubricating oil temperature L may be calculated based on the integrated value of the intake air amount GA after the internal combustion engine 10 is started, and the cooling water temperature W. When adopting such an aspect, a map representing the relationship between these parameters and the temperature L of the lubricating oil may be created in advance through experiments or simulations. The temperature L of the lubricating oil may be calculated based on the operating state of the internal combustion engine 10. In addition to the above, examples of parameters representing the operating state of the internal combustion engine 10 that can be used to understand the temperature L of the lubricating oil include the following. That is, for example, the engine rotational speed NE, engine load factor, gas pressure in the intake passage 15, gas pressure in the crank chamber 28, intake temperature P, exhaust temperature, operation duration of the internal combustion engine 10, etc. are listed. In order to grasp the values of these parameters, it is sufficient to attach various necessary sensors to the internal combustion engine 10.

- The content of the mixing amount calculation process is not limited to the example of the above embodiment. That is, the method of calculating the amount of mixed water D is not limited to the example of the above embodiment. For example, as information for calculating the amount of mixed water D, a characteristic map representing the relationship between the temperature L of the lubricating oil and the amount of mixed water D may be created in advance based on, for example, experiments or simulations. Here, the temperature L of the lubricating oil can reflect the degree of warming up of the internal combustion engine 10 and, by extension, the temperature of the wall surface of the crankcase 29. Therefore, by using the temperature L of the lubricating oil as an index, it is possible to grasp not only the amount of water that evaporates from the lubricating oil but also the amount of water that is newly mixed into the lubricating oil. Therefore, for each temperature L of the lubricating oil, the amount of water newly mixed into the lubricating oil within a unit time minus the amount of water that evaporates from the lubricating oil within a unit time is calculated as the net amount of water mixed into the lubricating oil. You can understand the amount of Based on the balance between the amount of water generated in the crankcase 29 and the amount of water evaporated from the lubricating oil as described in the above embodiment, in the specific map, the lower the temperature L of the lubricating oil, the larger the amount of mixed water D becomes. The mixed water amount D may be calculated using such a characteristic map. Any method may be used as long as the mixed water amount D can be calculated appropriately.

- When calculating the mixed water amount D, the amount of fuel injection may be taken into consideration. For example, in the embodiment described above, a provisional value of the new water amount may be calculated based on the first map, and the provisional value may be corrected according to the current fuel injection amount. Then, the corrected value may be treated as the final new water amount.

- The mixed water amount D may be calculated based on parameters other than the lubricating oil temperature L and the cooling water temperature W. As such parameters, various parameters described in the modification example related to calculation of the lubricating oil temperature L can also be used. A map representing the relationship between the amount of mixed water D and these parameters may be created in advance, for example, by experiment or simulation.

- The unit time defined by the first map, the second map, the specific map, etc. may be different from the execution interval of step S30 during which steps S10 to S50 are repeated. In this case, the amount of mixed water D per unit time ascertained from each map may be converted into a value corresponding to the execution interval of step S30.

- The operating state of the internal combustion engine 10 under a situation where specific conditions are satisfied is determined to a certain extent. Therefore, the amount of mixed water D during operation of the internal combustion engine 10 may be set in advance to a certain fixed value on the premise that the internal combustion engine 10 is in an operating state under a situation where a specific condition is satisfied. In the mixing amount calculation process, the fixed value may be repeatedly calculated. In this case, for example, a fixed value calculated based on experiment or simulation may be stored in the control device 100. When such an aspect is adopted, the processing load on the control device 100 when executing the mixing amount calculation process can be suppressed.

- The aspect of integration processing is not limited to the example of the above embodiment. That is, when the internal combustion engine 10 ends its operation without the lubricating oil temperature L reaching the specified oil temperature LK, it is not essential to store the end-time integrated value DAx. For example, the mixed water amount D may continue to be calculated even when the internal combustion engine 10 is intermittently stopped. At this time, the mixed water amount D is calculated as zero. Then, while the internal combustion engine 10 is intermittently stopped, the mixed water amount D continues to update the mixed water cumulative value DA. If such an aspect is adopted, the contamination accumulation value DA during the next operation of the internal combustion engine 10 will be the contamination accumulation value DA during the previous operation of the internal combustion engine 10, even if the end-time accumulation value DAx is not stored. The appropriate value will be inherited. For example, if the determination content in step S10 of the embodiment described above is set to be NO only when the power switch 60 is turned off, the amount of mixed water D and the mixed water amount D can be calculated even when the internal combustion engine 10 is intermittently stopped. It is possible to realize a mode in which the calculation of the value DA is continued.

- The above modification example in which the amount of mixed water D during operation of the internal combustion engine 10 is set to a fixed value may be combined with the above modification example in which the amount D of mixed water is set to zero while the internal combustion engine 10 is intermittently stopped. Then, the mixed water amount D may be set to a predetermined fixed value while the internal combustion engine 10 is operating, and the mixed water amount D may be set to zero while the internal combustion engine 10 is stopped.

- The method of determining the judgment value DK is not limited to the example of the above embodiment. The determination value DK may be determined as appropriate depending on the amount of water whose degree of mixing into the lubricating oil is to be determined.
- The method of determining the specified temperature PK and the specified oil temperature LK is not limited to the example of the above embodiment. The specified temperature PK and the specified oil temperature LK may be set to values that can specify an environment in which water is expected to be mixed into the lubricating oil.

- It is not essential to reset the contamination cumulative value DA when the lubricating oil temperature L reaches the specified oil temperature LK. Instead of resetting the contamination cumulative value DA when the lubricating oil temperature L reaches the specified oil temperature LK, for example, the contamination cumulative value DA may be reset each time the internal combustion engine 10 is started. In this case, the contamination cumulative value DA during the previous operation of the internal combustion engine 10 will not be carried over to the next operation of the internal combustion engine 10. For example, as part of collecting information to ascertain the state of the internal combustion engine 10, such an aspect is also effective when it is desired to ascertain the degree of water contamination in the lubricating oil after the internal combustion engine 10 has started. be.

- As described in the above modification example, the use of diagnostic processing is not limited to preventing blockages in oil passages. Depending on the purpose of diagnostic processing, countermeasure processing may not be necessary.
- The processing device that controls the internal combustion engine 10 and the lubricating oil dilution determination device may be configured as separate processing devices. In this case, the lubricating oil dilution determination device may be configured to be able to acquire information necessary to execute oil temperature calculation processing, mixed amount calculation processing, integration processing, and determination processing.

- The overall configuration of the internal combustion engine 10 is not limited to the example of the above embodiment. For example, the number of cylinders 11 may be changed. Further, the fuel injection valve 17 may be installed in the intake passage 15. Then, fuel may be supplied to the cylinder 11 via the intake passage 15. The internal combustion engine 10 only needs to have a cylinder 11, a crankcase 29, and an oil pan 27.

- The overall configuration of the vehicle 90 is not limited to the example of the embodiment described above. Vehicle 90 may have only internal combustion engine 10 as a drive source. Even in the vehicle 90 using only the internal combustion engine 10 as a driving source, by applying the diagnostic processing of the above embodiment, for example, it is possible to determine whether or not water equal to or greater than the determination value DK has mixed into the lubricating oil. In a vehicle 90 using only the internal combustion engine 10 as a driving source, the internal combustion engine 10 and the outside temperature sensor constitute an engine system.

- The configuration of the outside temperature sensor is not limited to the example of the above embodiment. That is, the outside temperature sensor may be configured by a device other than the intake temperature sensor 42. For example, the outside temperature sensor may be attached to a frame member of the vehicle 90, such as the front bumper of the vehicle 90. The outside temperature sensor only needs to be able to detect the outside temperature, that is, the temperature of the atmosphere.

<Technical philosophy>
The technical ideas that can be understood from the above embodiment and a plurality of modified examples will be described.
(Technical idea 1) An internal combustion engine that has a cylinder that is a space in which fuel is combusted, a crankcase whose inside communicates with the cylinder, and an oil pan that communicates with the crankcase and stores lubricating oil. and an outside temperature sensor that detects outside temperature, an oil temperature calculation process that calculates the temperature of the lubricating oil based on the operating state of the internal combustion engine, and an oil temperature calculation process that calculates the temperature of the lubricating oil based on the operating state of the internal combustion engine; When the specific conditions are that the oil temperature is less than a predetermined specified temperature and the outside temperature is less than a predetermined specified temperature, the current operation of the internal combustion engine is determined during the period when the specified conditions are satisfied. The specific condition is satisfied by performing a mixing amount calculation process that calculates the amount of mixed water that is the amount of water mixed into the lubricating oil per unit time in the state, and integrating the mixed water amount calculated in the mixing amount calculation process. an integration process that calculates an integrated value of the amount of water mixed in during a period of time; and a judgment process that determines whether or not a predetermined judgment value or more of water is mixed into the lubricating oil based on the integrated value. A lubricating oil dilution determination device that performs the following.

(Technical idea 2) In the integration process, when the temperature of the lubricating oil increases to the specified oil temperature while the internal combustion engine is operating, the integrated value is reset to zero, and the temperature of the lubricating oil increases to the specified oil temperature. When the internal combustion engine finishes operation without reaching the oil temperature, the integrated value at that point is stored as the ending integrated value, and the next time the internal combustion engine is started and operated, the ending integrated value is stored. The lubricating oil dilution determination device according to technical idea 1, wherein the integrated value is updated using the initial value as the initial value.

(Technical idea 3) Technical idea 1 or technique of calculating the amount of mixed water in the mixing amount calculation process such that when the temperature of the lubricating oil is low, the value is larger than when the temperature of the lubricating oil is high. The lubricating oil dilution determination device according to Concept 2.

(Technical idea 4) In the mixing amount calculation process, the mixing water amount is set to a predetermined constant value while the internal combustion engine is operating, and the mixing water amount is set to zero while the internal combustion engine is stopped.Technical idea 1 The lubricating oil dilution determination device described in .

(Technical idea 5) The engine system includes a motor generator in addition to the internal combustion engine as a drive source, and when it is determined in the determination process that water in an amount equal to or more than the determination value is mixed in the lubricating oil. The lubricating oil dilution determination device according to any one of Technical Ideas 1 to 4, which prohibits an electric mode in which only the motor generator is driven while stopping the internal combustion engine.

DESCRIPTION OF SYMBOLS 10... Internal combustion engine 11... Cylinder 27... Oil pan 29... Crank case 42... Intake temperature sensor 82... Motor generator 100... Control device

Claims (5)

An internal combustion engine having a cylinder which is a space in which fuel is combusted, a crankcase whose inside communicates with the cylinder, and an oil pan which communicates with the crankcase and stores lubricating oil;
an outside temperature sensor that detects outside temperature;
Targeting institutional systems with
an oil temperature calculation process that calculates the temperature of the lubricating oil based on the operating state of the internal combustion engine;
When a specific condition is that the temperature of the lubricating oil is less than a predetermined specified oil temperature and the outside temperature is less than a predetermined specified temperature, during a period when the specific condition is satisfied, a mixed water amount calculation process that calculates a mixed water amount that is the amount of water mixed into the lubricating oil per unit time in the current operating state of the internal combustion engine;
an integration process of calculating an integrated value of the amount of mixed water during a period in which the specific condition is satisfied by integrating the amount of mixed water calculated in the mixed amount calculation process;
a determination process that determines whether or not water in an amount equal to or greater than a predetermined determination value is mixed in the lubricating oil based on the integrated value;
Lubricating oil dilution determination device. In the integration process,
If the temperature of the lubricating oil increases to the specified oil temperature during operation of the internal combustion engine, resetting the integrated value to zero;
If the internal combustion engine ends its operation without the temperature of the lubricating oil reaching the specified oil temperature, the integrated value at that point is stored as the integrated value at the end, and the internal combustion engine is then started and operated. The lubricating oil dilution determination device according to claim 1, wherein the integrated value is updated using the end integrated value as an initial value. In the mixing amount calculation process,
The lubricating oil dilution determination device according to claim 1, wherein the amount of mixed water is calculated so that when the temperature of the lubricating oil is low, the value is larger than when the temperature of the lubricating oil is high. In the mixing amount calculation process,
The lubricating oil dilution determination device according to claim 1, wherein the amount of mixed water is set to a predetermined constant value while the internal combustion engine is operating, and the amount of mixed water is set to zero while the internal combustion engine is stopped. The engine system includes a motor generator in addition to the internal combustion engine as a driving source,
According to claim 1, if it is determined in the determination process that water in an amount equal to or greater than the determination value is mixed in the lubricating oil, an electric mode in which only the motor generator is driven while stopping the internal combustion engine is prohibited. Lubricating oil dilution determination device.

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