Lubricant dilution suppression device

Abstract

To provide a lubricating oil dilution suppressing device capable of suppressing the increase of a dilution ratio of lubricating oil.SOLUTION: A lubricating oil dilution suppressing device 1 includes a tank 2, a gas discharge passage 3, an oil introduction passage 4, a gas introduction passage 5, an oil discharge passage 6, a solenoid valve 7, and a control unit 8. The tank 2 is arranged outside or inside a crankcase CC of an internal combustion engine ICE. The gas discharge passage 3 discharges gas from the inside of the tank 2 to the outside of the tank 2, and the oil introduction passage 4 introduces lubricating oil LO from an oil pan OP of the internal combustion engine ICE into the inside of the tank 2. The gas introduction passage 5 introduces gas from the outside of the tank 2 into the inside of the tank 2, and the oil discharge passage 6 discharges the lubricating oil LO from the tank 2 to the oil pan OP. The solenoid valves 7 are provided in the gas outlet passage 3, the oil introduction passage 4, the gas introduction passage 5, and the oil introduction passage 6, respectively, and the control unit 8 controls the opening and closing of the solenoid valves 7 individually.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a lubricating oil dilution suppression device. Background Art

[0002] Conventionally, control devices for internal combustion engines are known (for example, Patent Document 1 below). The control device for an internal combustion engine described in Patent Document 1 increases the oil temperature of the lubricating oil by injecting lubricating oil from an oil jet when the oil temperature of the lubricating oil belongs to a hydraulic oil operating temperature range, thereby suppressing an increase in the dilution rate of the lubricating oil. Prior Art Documents Patent Documents

[0003] Patent Document 1 Japanese Unexamined Patent Publication No. 2010-216266 Summary of the Invention Problem to be Solved by the Invention

[0004] With the control device for an internal combustion engine described in Patent Document 1, for example, in a case where the internal combustion engine is driven intermittently for a short period of time and cold starting is repeated, the temperature of the lubricating oil cannot be sufficiently increased, which may cause the dilution rate of the lubricating oil to increase.

[0005] The present disclosure provides a lubricating oil dilution suppression device capable of suppressing an increase in the dilution rate of lubricating oil. Means for Solving the Problem

[0006] One aspect of the present disclosure provides a lubricating oil dilution suppression device comprising: a tank disposed outside or inside the crankcase of an internal combustion engine; a gas outlet passage for leading gas from inside the tank to outside the tank; an oil inlet passage for introducing lubricating oil from the oil pan of the internal combustion engine into the tank; a gas inlet passage for leading gas from outside the tank to inside the tank; an oil outlet passage for leading the lubricating oil from the tank to the oil pan; solenoid valves provided in each of the gas outlet passage, the oil inlet passage, the gas inlet passage, and the oil outlet passage; and a control unit for individually controlling the opening and closing of the solenoid valves. [Effects of the Invention]

[0007] According to the above-described aspects of this disclosure, a lubricating oil dilution suppression device capable of suppressing an increase in the dilution ratio of the lubricating oil can be provided. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram showing an embodiment of the lubricating oil dilution suppression device according to this disclosure. [Figure 2] Figure 1 is a flowchart showing the processing flow by the control unit of the lubricating oil dilution suppression device. [Figure 3] Figure 2 is a graph illustrating the process for calculating the amount of water and fuel mixed in. [Figure 4] Figure 1 is a timing diagram showing the operation of each part of the lubricating oil dilution suppression device. [Figure 5] Figure 1 is a flowchart showing the processing flow by the control unit of the lubricating oil dilution suppression device. [Figure 6] Figure 1 is a flowchart showing the processing flow by the control unit of the lubricating oil dilution suppression device. [Modes for carrying out the invention]

[0009] The following describes embodiments for carrying out the invention with reference to the drawings.

[0010] Figure 1 is a schematic diagram showing an embodiment of the lubricating oil dilution suppression device according to this disclosure. The lubricating oil dilution suppression device 1 of this embodiment is installed in vehicles equipped with an internal combustion engine (ICE), such as internal combustion engine vehicles, battery electric vehicles (BEVs) equipped with an internal combustion engine as a generator, hybrid electric vehicles (HEVs), or plug-in hybrid electric vehicles (PHEVs). The fuel used in the internal combustion engine (ICE) includes, for example, conventional fuels such as gasoline, diesel fuel, and LPG, as well as carbon-neutral fuels such as hydrogen, synthetic fuels, and biomass fuels.

[0011] An internal combustion engine (ICE) includes, for example, a cylinder head CH, a cylinder block CB, a crankcase CC, and an oil pan OP. The ICE also includes, for example, an intake passage IP equipped with an air cleaner AC and a throttle valve Vth, and an exhaust passage EP equipped with a three-way catalytic converter TC. The three-way catalytic converter TC may be an electrically heated catalyst that can be heated by, for example, an electric heater EH.

[0012] Furthermore, the internal combustion engine (ICE) has, for example, a bypass passage BP and a blow-by gas passage BGP. The bypass passage BP connects, for example, the intake passage IP upstream of the throttle valve Vth to the cylinder head CH. The blow-by gas passage BGP connects, for example, the crankcase CC to the intake manifold IM. The blow-by gas passage BGP is provided with, for example, a PCV valve Vpc.

[0013] Furthermore, the internal combustion engine (ICE) includes, for example, an oil pump Po and a vacuum pump Pv. The oil pump Po is driven, for example, by the rotation of a crankshaft CS connected to a piston PI via a connecting rod CR, and delivers lubricating oil LO stored in the oil pan OP to various parts of the internal combustion engine (ICE). The suction port of the vacuum pump Pv is connected, for example, to the negative pressure chamber of a brake booster used to assist the driver's brake operation. The discharge port of the vacuum pump Pv is connected, for example, to a blow-by gas passage BGP.

[0014] Furthermore, the internal combustion engine (ICE) is equipped with a lubricating oil dilution suppression device 1 that suppresses the dilution of lubricating oil LO by, for example, water or fuel. The lubricating oil dilution suppression device 1 includes, for example, a tank 2, a gas outlet 3, an oil inlet 4, a gas inlet 5, an oil outlet 6, a plurality of solenoid valves 7, and a control unit 8.

[0015] Tank 2 is located, for example, outside the crankcase CC of an internal combustion engine (ICE). Alternatively, Tank 2 may be located inside the crankcase CC. Tank 2 is connected, for example, to the crankcase CC via a gas outlet 3 and to the oil pan OP via an oil inlet 4. Alternatively, Tank 2 is connected to the intake passage IP via a gas inlet 5 and to the oil pan OP via an oil outlet 6. Tank 2 is located, for example, vertically above the oil pan OP and temporarily stores lubricating oil LO introduced from the oil pan OP via the oil inlet 4.

[0016] The volume of lubricating oil LO introduced into tank 2 is, for example, smaller than the volume of lubricating oil LO stored in oil pan OP. The volume of lubricating oil LO introduced into tank 2 is set to a range that does not interfere with the operation of the internal combustion engine ICE when lubricating oil LO is introduced from oil pan OP to tank 2.

[0017] Tank 2 includes, for example, a pressure sensor 21, a temperature sensor 22, and a heating device 23. The pressure sensor 21 detects, for example, the internal pressure of Tank 2 and outputs the detection result to the control unit 8. The temperature sensor 22 detects, for example, the temperature of the lubricating oil LO stored in Tank 2 and outputs the detection result to the control unit 8. The heating device 23 is, for example, an electric heater, which is controlled by the control unit 8 to heat the lubricating oil LO inside Tank 2.

[0018] The gas outlet path 3 is, for example, a path that guides gas from the inside of the tank 2 to the outside of the tank 2. In the flow direction Go of gas passing through the gas outlet path 3, the upstream end of the gas outlet path 3 is connected to, for example, the upper part of the tank 2, and the downstream end of the tank 2 is connected to, for example, a crankcase CC. The downstream end of the gas outlet path 3 may be connected to, for example, the suction port of a vacuum pump Pv.

[0019] The oil introduction path 4 is, for example, a path that introduces lubricating oil LO from an oil pan OP of an internal combustion engine ICE to the inside of the tank 2. In the flow direction Oi of lubricating oil LO passing through the oil introduction path 4, the upstream end of the oil introduction path 4 is connected to, for example, the oil pan OP, and the downstream end of the oil introduction path 4 is connected to, for example, the bottom of the tank 2.

[0020] The gas introduction path 5 is, for example, a path that introduces gas from the outside of the tank 2 to the inside of the tank 2. In the flow direction Gi of gas passing through the gas introduction path 5, the upstream end of the gas introduction path 5 is connected to an intake passage IP at a position upstream of a throttle valve Vth, for example, and the downstream end of the gas introduction path 5 is connected to, for example, the upper part of the tank 2.

[0021] The oil outlet path 6 is, for example, a path that guides lubricating oil LO from the tank 2 to the oil pan OP. In the flow direction Oo of lubricating oil LO passing through the oil outlet path 6, the upstream end of the oil outlet path 6 is connected to, for example, the bottom of the tank 2, and the downstream end of the oil outlet path 6 is connected to, for example, the oil pan OP.

[0022] The solenoid valves 7 are provided in each of, for example, the gas outlet path 3, the oil introduction path 4, the gas introduction path 5, and the oil outlet path 6. Each solenoid valve 7 is controlled by, for example, a control unit 8 and opens and closes individually. The solenoid valves 7 include, for example: a gas outlet valve Vgo that opens and closes the gas outlet path 3, an oil introduction valve Voi that opens and closes the oil introduction path 4, a gas introduction valve Vgi that opens and closes the gas introduction path 5, and an oil outlet valve Voo that opens and closes the oil outlet path 6.

[0023] The control unit 8, for example, individually controls the opening and closing of multiple solenoid valves 7. The control unit 8 is an electronic control unit (ECU) composed of, for example, a central processing unit (CPU) and one or more microcontrollers including memory such as RAM or ROM. The control unit 8 controls each part of the internal combustion engine ICE and the lubricating oil dilution suppression device 1 by, for example, executing a program stored in memory. The control unit 8 may also serve as an engine control unit for controlling the internal combustion engine ICE, or it may be provided separately from the engine control unit.

[0024] Figure 2 is a flowchart showing an example of the processing flow by the control unit 8 of the lubricating oil dilution suppression device 1 shown in Figure 1. When the start switch of a vehicle equipped with an internal combustion engine (ICE) is turned on, for example, the control unit 8 repeatedly executes the processing flow shown in Figure 2 at a predetermined cycle until the start switch is turned off. When the control unit 8 starts the processing flow shown in Figure 2, it executes a process S1, for example, to calculate the amount of water and fuel mixed into the lubricating oil LO.

[0025] Figure 3 is a graph illustrating the process S1 for calculating the amount of water and fuel mixed in, as shown in Figure 2. In this process S1, the control unit 8 calculates the amount of water mixed in with the lubricating oil LO, for example, by following the procedure below.

[0026] The control unit 8, for example, refers to correlation data stored in memory beforehand. The correlation data is data that defines the correlation between the internal combustion engine ICE's coolant temperature Tw, the internal combustion engine ICE's load τ, the internal combustion engine ICE's rotational speed N, and the water mixing rate Rw with respect to the lubricating oil LO, as shown in Figure 3. The control unit 8 also retrieves, for example, the internal combustion engine ICE's history data stored in memory. The history data includes, for example, the history of the internal combustion engine ICE's coolant temperature Tw, the history of the internal combustion engine ICE's load τ, and the history of the internal combustion engine ICE's rotational speed N.

[0027] The control unit 8 calculates, for example, the water mixing rate Rw into the lubricating oil LO based on the correlation data and historical data described above. For example, as shown in Figure 3, the water mixing rate Rw2 into the lubricating oil LO when the cooling water temperature Tw, load τ, and rotational speed N are relatively low is lower than the water mixing rate Rw1 into the lubricating oil LO when the cooling water temperature Tw, load τ, and rotational speed N are relatively high.

[0028] Furthermore, the control unit 8 calculates the amount of water mixed into the lubricating oil LO based on the calculated water mixing rate Rw and its duration. The control unit 8 also calculates the amount of water mixed into the lubricating oil LO up to the current process S1 by adding the amount of water newly calculated in the current process S1 with the amount of water mixed in calculated and accumulated in previous processes S1.

[0029] Furthermore, the control unit 8 calculates, for example, the amount of fuel mixed into the lubricating oil LO in the same way as the amount of water mixed into the lubricating oil LO. Once the control unit 8 has finished the process S1 which calculates the amounts of water and fuel mixed into the lubricating oil LO, it executes a process S2 which determines, for example, whether or not the water or fuel mixed into the lubricating oil LO needs to be evaporated, as shown in Figure 2.

[0030] In this process S2, the control unit 8 determines, for example, whether the amount of water and the amount of fuel mixed into the lubricating oil LO, calculated in the previous process S1, exceed their respective thresholds. Here, if the control unit 8 determines, for example, that neither the amount of water nor the amount of fuel mixed into the lubricating oil LO exceeds their respective thresholds (NO), it terminates the process flow shown in Figure 2.

[0031] Subsequently, the control unit 8 repeats the processing flow shown in Figure 2 at predetermined intervals, for example, until the vehicle's start switch is turned off. As a result, the control unit 8 determines in the aforementioned processing S2 that the amount of water mixed with the lubricating oil LO exceeds the threshold, or that the amount of fuel mixed in exceeds the threshold (YES). In this case, the control unit 8 sequentially executes, for example, the oil introduction processing S3, the negative pressure evaporation processing S4, and the oil discharge processing S5 shown in Figure 2.

[0032] Figure 4 is a timing diagram showing the operation of each part of the lubricating oil dilution suppression device 1 shown in Figure 1. For example, as shown in the top graph of Figure 4, at time t0 before the control unit 8 starts the oil introduction process S3, the liquid level OL of the lubricating oil LO stored inside the tank 2 is approximately at the lowest level (L).

[0033] Furthermore, as shown in the second graph from the top in Figure 4, the internal pressure Pt of tank 2 is, for example, approximately equal to atmospheric pressure (AP). Also, as shown in the third graph from the top in Figure 4, the vacuum pump Pv is, for example, turned ON and in operation. Furthermore, as shown in the graphs from the fourth to the bottom in Figure 4, among the multiple solenoid valves 7, for example, the oil outlet valve Voo is in the open state (O), while the other oil inlet valve Voi, gas inlet valve Vgi, and gas outlet valve Vgo are in the closed state (C).

[0034] Subsequently, when the oil introduction process S3 is started, the control unit 8 controls the individual solenoid valves 7 to open the gas outlet valve Vgo and the oil introduction valve Voi, and close the gas introduction valve Vgi and the oil outlet valve Voo. As a result, for example, as shown in the bottom and fourth-to-bottom graphs of Figure 4, at time t1, the gas outlet valve Vgo and the oil introduction valve Voi transition from the closed state (C) to the open state (O). Also, as shown in the second-to-last graph of Figure 4, the gas introduction valve Vgi remains in the closed state (C), and as shown in the third-to-last graph of Figure 4, the oil outlet valve Voo transitions from the open state (O) to the closed state (C).

[0035] As a result, as shown in Figure 1, the gas inside tank 2 flows in the flow direction Go from tank 2 to crankcase CC through the gas outlet passage 3 and the open (O) gas outlet valve Vgo. Consequently, as shown in the second graph from the top in Figure 4, the internal pressure Pt of tank 2 decreases, and the lubricating oil LO stored in oil pan OP flows in the flow direction Oi from oil pan OP to tank 2 through the oil inlet passage 4 and the open (O) oil inlet valve Voi.

[0036] As a result, lubricating oil LO is introduced from the oil pan OP into the tank 2, and the liquid level OL of the lubricating oil LO in the tank 2 rises, as shown in the top graph of Figure 4. Then, for example, at time t2, when the liquid level OL of the lubricating oil LO in the tank 2 reaches the highest level (H), the control unit 8 terminates the oil introduction process S3 shown in Figure 2, for example, and executes the next negative pressure evaporation process S4.

[0037] In this negative pressure evaporation process S4, the control unit 8 controls multiple solenoid valves 7 to open and close the gas inlet valve Vgi while keeping the gas outlet valve Vgo open and the oil inlet valve Voi and oil outlet valve Voo closed. Specifically, the control unit 8 opens and closes the gas inlet valve Vgi to maintain the internal pressure Pt of the tank 2 at a predetermined negative pressure VP. More specifically, the control unit 8 controls the opening degree of the gas outlet valve Vgo between a closed state (C) and an open state (O) by performing feedback control of the internal pressure Pt of the tank 2 to maintain the internal pressure Pt of the tank 2 at a predetermined negative pressure VP.

[0038] Here, the predetermined negative pressure VP in the negative pressure evaporation process S4 is set to a pressure suitable for the evaporation of water and fuel mixed in the lubricating oil LO, for example. This predetermined negative pressure VP is set to a pressure lower than the internal pressure of the crankcase CC in an internal combustion engine ICE during operation. More specifically, for example, if the internal pressure of the crankcase CC in an internal combustion engine ICE during operation is several negative kilopascals in gauge pressure, the predetermined negative pressure VP of the tank 2 can be set to, for example, several tens of negative kilopascals in gauge pressure.

[0039] In the negative pressure evaporation process S4, the control unit 8 maintains the internal pressure Pt of the tank 2 at a predetermined negative pressure VP for a predetermined period from time t2 to time t3. This predetermined period is set to, for example, the period required to evaporate the amount of water and fuel mixed in, which was calculated in the process S1 described above. The period required to evaporate the water and fuel can be calculated, for example, based on the internal pressure Pt of the tank 2, the temperature of the lubricating oil LO, and the amount of water and fuel mixed in.

[0040] Here, as shown in Figure 1, for example, if the tank 2 has a heating device 23, the control unit 8 may control the heating device 23 in the negative pressure evaporation process S4 to heat the lubricating oil LO inside the tank 2 to a predetermined temperature. The predetermined temperature of the lubricating oil LO is set to a temperature that allows sufficient evaporation of the water and fuel mixed in the lubricating oil LO when the internal pressure Pt of the tank 2 is maintained at a predetermined negative pressure VP.

[0041] By executing the negative pressure evaporation process S4, the water and fuel mixed in the lubricating oil LO in the tank 2 evaporate, and the liquid level OL of the lubricating oil LO gradually decreases, as shown in the top graph of Figure 4. The control unit 8 terminates the negative pressure evaporation process S4 after a predetermined period has elapsed from the time t2 when the negative pressure evaporation process S4 was started, and then executes the next oil discharge process S5, as shown in Figure 2.

[0042] When this oil discharge process S5 is started, the control unit 8 closes the gas discharge valve Vgo at time t3, changing it from the open state (O) to the closed state (C), as shown in the bottom and fourth-to-bottom graphs of Figure 4, for example, and maintains the closed state (C) of the oil inlet valve Voi. Also, at time t3, the control unit 8 opens the gas inlet valve Vgi and the oil discharge valve Voo, changing them from the closed state (C) to the open state (O), as shown in the second and third-to-bottom graphs of Figure 4.

[0043] As a result, the control unit 8 directs the lubricating oil LO from the tank 2 to the oil pan OP. Specifically, air is introduced into the tank 2 from the intake passage IP via the gas inlet passage 5 and the open (O) gas outlet valve Vgo. Consequently, as shown in the second graph from the top in Figure 4, the internal pressure Pt of the tank 2 rises from a predetermined negative pressure VP and returns to an internal pressure Pt that is approximately equal to atmospheric pressure AP.

[0044] Furthermore, the lubricating oil LO inside the tank 2 flows in the flow direction Oo from the tank 2 to the oil pan OP through the oil outlet passage 6 and the open (O) oil outlet valve Voo, for example, due to the action of gravity, and is discharged from the inside of the tank 2 to the oil pan OP. As a result, for example, as shown in the top graph of Figure 4, the liquid level OL of the lubricating oil LO inside the tank 2 gradually decreases and falls to the lowest level (L) at time t4. After that, the control unit 8 performs a process S6 to update the amount of water and fuel mixed in, for example, as shown in Figure 2.

[0045] In this process S6, the control unit 8 updates the amount of water and fuel mixed into the lubricating oil LO by subtracting the amount of water and fuel evaporated in the previous negative pressure evaporation process S4 from the total amount of water and fuel mixed into the lubricating oil LO before the previous negative pressure evaporation process S4 was executed. More specifically, the control unit 8 calculates and updates the amount of water mixed into the lubricating oil LO based on the following equation (1), for example.

[0046] Amount of water contamination = Previous value of water contamination × (1 - Amount of lubricating oil in the tank / Total amount of lubricating oil) ... (1)

[0047] Furthermore, the control unit 8 can calculate and update, for example, the amount of fuel mixed with the lubricating oil LO, in the same way as the amount of water mixed in. Subsequently, the control unit 8 performs a process S7 to determine, for example, whether the evaporation of the water and fuel mixed with the lubricating oil LO has been completed, as shown in Figure 2.

[0048] In this process S7, the control unit 8 compares, for example, a threshold value for the amount of water mixed in that is pre-stored in memory with the amount of water mixed in the lubricating oil LO after the update. Similarly, the control unit 8 compares, for example, a threshold value for the amount of fuel mixed in that is pre-stored in memory with the amount of fuel mixed in the lubricating oil LO after the update.

[0049] In this process S7, the control unit 8 determines, for example, that the evaporation of water or fuel mixed into the lubricating oil LO is not complete (NO) if the amount of water mixed in after the update exceeds a threshold, or if the amount of fuel mixed in after the update exceeds a threshold. In this case, the control unit 8 sequentially repeats, for example, the oil introduction process S3, the negative pressure evaporation process S4, the oil discharge process S5, and the process S6 for updating the amount of water and fuel mixed in.

[0050] On the other hand, in the aforementioned process S7, the control unit 8 determines that the evaporation of water and fuel mixed into the lubricating oil LO is complete (YES) if, for example, the amount of water mixed in after the update is below a threshold and the amount of fuel mixed in after the update is below a threshold. In this case, the control unit 8 terminates the process flow shown in Figure 2, for example, and repeats the process flow shown in Figure 2 at a predetermined cycle until the start switch of the vehicle equipped with the internal combustion engine ICE is turned off.

[0051] The operation of the lubricating oil dilution suppression device 1 of this embodiment will be explained below.

[0052] The lubricating oil dilution suppression device 1 of this embodiment includes a tank 2 located outside or inside the crankcase CC of an internal combustion engine ICE. The lubricating oil dilution suppression device 1 also includes a gas outlet passage 3 for leading gas from inside the tank 2 to the outside of the tank 2, and an oil inlet passage 4 for introducing lubricating oil LO from the oil pan OP of the internal combustion engine ICE into the tank 2. The lubricating oil dilution suppression device 1 also includes a gas inlet passage 5 for leading gas from outside the tank 2 to the inside of the tank 2, and an oil outlet passage 6 for leading lubricating oil LO from the tank 2 to the oil pan OP. Furthermore, the lubricating oil dilution suppression device 1 includes solenoid valves 7 provided in each of the gas outlet passage 3, oil inlet passage 4, gas inlet passage 5, and oil outlet passage 6, and a control unit 8 for individually controlling the opening and closing of these solenoid valves 7.

[0053] With this configuration, the lubricating oil dilution suppression device 1 of this embodiment allows the control unit 8 to control the opening and closing of the solenoid valves 7 provided in each of the gas outlet passage 3, oil inlet passage 4, gas inlet passage 5, and oil outlet passage 6. This allows the gas inside the tank 2 to be discharged to the outside of the tank 2 via the gas outlet passage 3, thereby lowering the internal pressure Pt of the tank 2, and lubricating oil LO to be introduced into the tank 2 from the oil pan OP via the oil inlet passage 4.

[0054] Furthermore, by releasing the gas inside the tank 2 to the outside of the tank 2 via the gas outlet passage 3, and introducing a predetermined amount of gas from the outside of the tank 2 to the inside of the tank 2 via the gas inlet passage 5, the internal pressure Pt of the tank 2 can be maintained at a predetermined negative pressure VP. As a result, the water and fuel mixed in the lubricating oil LO can be efficiently evaporated inside the tank 2.

[0055] Furthermore, by introducing gas from outside the tank 2 into the tank 2 via the gas introduction passage 5, the lubricating oil LO can be discharged from inside the tank 2 to the oil pan OP via the oil discharge passage 6. Therefore, according to this embodiment, even when the internal combustion engine ICE is driven intermittently for short periods of time and cold starts are repeated, it is possible to provide a lubricating oil dilution suppression device 1 that can evaporate water and fuel mixed in the lubricating oil LO inside the tank 2 and suppress an increase in the dilution rate of the lubricating oil LO.

[0056] Furthermore, in the lubricating oil dilution suppression device 1 of this embodiment, the solenoid valve 7 includes a gas outlet valve Vgo that opens and closes the gas outlet passage 3, an oil inlet valve Voi that opens and closes the oil inlet passage 4, a gas inlet valve Vgi that opens and closes the gas inlet passage 5, and an oil outlet valve Voo that opens and closes the oil outlet passage 6. The control unit 8 sequentially executes an oil introduction process S3, a negative pressure evaporation process S4, and an oil outlet process S5. The oil introduction process S3 is a process in which lubricating oil LO is introduced from the oil pan OP to the tank 2 by opening the gas outlet valve Vgo and the oil inlet valve Voi and closing the gas inlet valve Vgi and the oil outlet valve Voo. The negative pressure evaporation process S4 is a process in which the gas outlet valve Vgo is opened and the oil inlet valve Voi and the oil outlet valve Voo are closed, and the gas inlet valve Vgi is opened and closed to maintain the internal pressure Pt of the tank 2 at a predetermined negative pressure VP. The oil discharge process S5 is a process in which lubricating oil LO is discharged from tank 2 to oil pan OP by closing the gas discharge valve Vgo and oil inlet valve Voi and opening the gas inlet valve Vgi and oil discharge valve Voo.

[0057] With this configuration, the lubricating oil dilution suppression device 1 of this embodiment allows the control unit 8 to perform the oil introduction process S3. This allows the gas inside the tank 2 to be released to the outside of the tank 2 via the gas outlet passage 3 and the open (O) gas outlet valve Vgo, thereby reducing the internal pressure Pt of the tank 2. As a result, lubricating oil LO can be introduced from the oil pan OP into the tank 2 via the oil introduction passage 4 and the open (O) oil introduction valve Voi.

[0058] Furthermore, after introducing lubricating oil LO into the tank 2, the control unit 8 can perform negative pressure evaporation processing S4. This allows the gas inside the tank 2 to be discharged to the outside of the tank 2 via the gas outlet passage 3 and the open (O) gas outlet valve Vgo, while a predetermined amount of gas is introduced from the outside of the tank 2 into the tank 2 via the gas inlet passage 5 and the gas inlet valve Vgi. As a result, the internal pressure Pt of the tank 2 can be maintained at a predetermined negative pressure VP, effectively evaporating the water and fuel mixed in the lubricating oil LO introduced into the tank 2, and discharging them to the outside of the tank 2 via the gas outlet passage 3 and the gas outlet valve Vgo.

[0059] Furthermore, after the water and fuel mixed in the lubricating oil LO introduced into the tank 2 have sufficiently evaporated, the control unit 8 can perform the oil discharge process S5. As a result, gas is introduced into the tank 2 from outside through the gas introduction passage 5 and the open (O) gas introduction valve Vgi, and the lubricating oil LO, from which the mixed water and fuel have been sufficiently removed, is discharged from the tank 2 to the oil pan OP through the oil discharge passage 6 and the open (O) oil discharge valve Voo.

[0060] By repeatedly performing the oil introduction process S3, negative pressure evaporation process S4, and oil discharge process S5 described above, it becomes possible to evaporate and thoroughly remove water and fuel mixed in the lubricating oil LO stored in the oil pan OP. Therefore, the lubricating oil dilution suppression device 1 of this embodiment can effectively suppress the increase in the dilution rate of the lubricating oil LO.

[0061] Furthermore, if the lubricating oil dilution suppression device 1 of this embodiment further includes a heating device 23 for heating the lubricating oil LO inside the tank 2, the control unit 8 can control the heating device 23 in the negative pressure evaporation process S4 to heat the lubricating oil LO to a predetermined temperature.

[0062] With this configuration, the lubricating oil dilution suppression device 1 of this embodiment makes it possible to more effectively evaporate and remove water and fuel mixed in the lubricating oil LO during the negative pressure evaporation process S4. Therefore, the lubricating oil dilution suppression device 1 of this embodiment can more effectively suppress the increase in the dilution ratio of the lubricating oil LO, even when the internal combustion engine ICE is driven intermittently for short periods and cold starts are repeated.

[0063] Furthermore, if the downstream end of the gas outlet 3 connected to the tank 2, opposite to the upstream end, is connected to the suction port of the vacuum pump Pv, the internal pressure Pt of the tank 2 can be reduced by the vacuum pump Pv. Therefore, in the negative pressure evaporation process S4, it is possible to easily reduce the internal pressure Pt of the tank 2 to a predetermined negative pressure VP.

[0064] As described above, according to this embodiment, even when the internal combustion engine ICE is driven intermittently for short periods and cold starts are repeated, it is possible to provide a lubricating oil dilution suppression device 1 that can suppress an increase in the dilution rate of lubricating oil LO. The lubricating oil dilution suppression device according to this disclosure is not limited to the configuration of the lubricating oil dilution suppression device 1 according to the above embodiment. Hereinafter, with reference to Figures 1 to 4, as well as Figures 5 and 6, modified examples of the lubricating oil dilution suppression device 1 according to the above embodiment will be described.

[0065] The lubricating oil dilution suppression device 1 in each of the following modified examples differs from the lubricating oil dilution suppression device 1 in the above-described embodiment in the processing flow of the control unit 8. The other components of the lubricating oil dilution suppression device 1 in each modified example are the same as those of the lubricating oil dilution suppression device 1 in the above-described embodiment, so the same reference numerals are used for the same parts and their description is omitted.

[0066] Figure 5 is a flowchart showing a modified version of the processing flow by the control unit 8 of the lubricating oil dilution suppression device 1 in Figure 1. In this modified version, the vehicle equipped with the internal combustion engine ICE shown in Figure 1 is, for example, a PHEV that can be connected to an external power source, or an EV equipped with an internal combustion engine ICE as a generator.

[0067] In the modified example shown in Figure 5, if the control unit 8 determines in the aforementioned process S2 that evaporation of water and fuel mixed in the lubricating oil LO is necessary (YES), it executes process S8 to determine whether the vehicle equipped with the internal combustion engine ICE is connected to an external power source. In this process S8, if the control unit 8 determines that the vehicle is not connected to an external power source (NO), it terminates the process flow shown in Figure 5.

[0068] On the other hand, in process S8, if the control unit 8 determines that the vehicle is connected to an external power source (YES), it executes the processes from the oil introduction process S3 to process S6, which updates the amount of water and fuel mixed in. Here, for example, in the oil introduction process S3, the control unit 8 uses the external power source to operate the heating device 23 and heat the lubricating oil LO inside the tank 2. Also, for example, in the oil introduction process S3 and the negative pressure evaporation process S4, the control unit 8 uses the external power source to operate the vacuum pump Pv connected to the downstream end of the gas outlet passage 3.

[0069] Subsequently, the control unit 8 performs a process S7 to determine whether the evaporation of water and fuel mixed in the lubricating oil LO has been completed, similar to the embodiment described above. In addition, in the modified example shown in Figure 5, the control unit 8 also determines in process S7 whether it is necessary to interrupt the negative pressure evaporation process S4, for example, whether the amount of evaporated fuel has reached the limit that can be adsorbed by the three-way catalyst TC, or whether the connection between the vehicle and the external power supply has been disconnected.

[0070] In process P7, if the control unit 8 determines, for example, that the evaporation of water or fuel is not complete and that there is no need to interrupt the negative pressure evaporation process S4 (NO), it repeatedly executes the oil introduction process S3 to process S7 described above. On the other hand, in process P7, if the control unit 8 determines, for example, that the evaporation of water or fuel is complete or that there is a need to interrupt the negative pressure evaporation process S4 (YES), it terminates the process flow shown in Figure 5.

[0071] As described above, in the modified example shown in Figure 5, the control unit 8 of the lubricating oil dilution suppression device 1 performs the oil introduction process S3, the negative pressure evaporation process S4, and the oil discharge process S5 when the vehicle equipped with the internal combustion engine ICE is connected to an external power source.

[0072] With this configuration, the lubricating oil dilution suppression device 1 shown in the modified example in Figure 5 can suppress the increase in the dilution rate of the lubricating oil LO by evaporating water and fuel mixed in the lubricating oil LO, even when the internal combustion engine ICE is not running and the temperature of the internal combustion engine ICE is low, such as when the vehicle is being charged. Furthermore, by using an external power source, it is not necessary to drive the internal combustion engine ICE, and carbon dioxide emissions can be reduced.

[0073] Figure 6 is a flowchart showing a modified example of the processing flow by the control unit 8 of the lubricating oil dilution suppression device 1 shown in Figure 1.

[0074] The control unit 8 of the modified lubricant dilution suppression device 1 shown in Figure 6 differs from the modified lubricant dilution suppression device 1 shown in Figure 5 in that, after a process S8 that determines whether or not the vehicle is connected to an external power source, the control unit 8 performs a process S9 in which it heats the three-way catalyst TC.

[0075] In the example shown in Figure 6, the control unit 8, for example, determines in process S2 that it is necessary to evaporate the water or fuel mixed in the lubricating oil LO (YES), and in process S8 determines that the vehicle is connected to an external power source (YES), then executes process S9 to heat the three-way catalytic converter TC.

[0076] In this process S9, the control unit 8 controls, for example, the electric heater EH that heats the three-way catalyst TC to heat the three-way catalyst TC to its activation start temperature. After that, the control unit 8 executes process S6 to update the amount of water and fuel mixed in from the oil introduction process S3 described above. Here, the fuel evaporated from the lubricating oil LO in the negative pressure evaporation process S4 is purified by the three-way catalyst TC heated by the electric heater EH.

[0077] Subsequently, the control unit 8 executes a process S7, for example, to determine whether evaporation is complete or interrupted. In this process S7, if the control unit 8 determines, for example, that the amount of water and fuel mixed into the lubricating oil LO updated in the previous process S6 is below a threshold, or that the connection between the vehicle and the external power supply has been disconnected (YES), it terminates the process flow shown in Figure 6.

[0078] As described above, in the modified example shown in Figure 6, the control unit 8 of the lubricating oil dilution suppression device 1 heats the three-way catalytic converter TC, which is an electrically heated catalytic converter provided in the exhaust passage of the internal combustion engine ICE, during the negative pressure evaporation treatment S4 when the vehicle is connected to an external power source.

[0079] With this configuration, the lubricating oil dilution suppression device 1 of this embodiment can purify harmful substances such as hydrocarbons generated by the evaporation of fuel mixed in the lubricating oil LO during the negative pressure evaporation treatment S4 using a three-way catalyst TC heated with an external power source. Therefore, the limitation on the amount of harmful substances adsorbed by the three-way catalyst TC when the internal combustion engine ICE is not operating is eliminated, and it becomes possible to evaporate all of the fuel mixed in the lubricating oil LO.

[0080] Preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the embodiments described above. Various modifications or substitutions can be applied to the embodiments described above without departing from the scope of the present invention. [Explanation of Symbols]

[0081] 1: Lubricating oil dilution suppression device, 2: Tank, 23: Heating device, 3: Gas outlet passage, 4: Oil inlet passage, 5: Gas inlet passage, 6: Oil outlet passage, 7: Solenoid valve, 8: Control unit, CC: Crankcase, EP: Exhaust passage, ICE: Internal combustion engine, LO: Lubricating oil, OP: Oil pan, S3: Oil inlet treatment, S4: Negative pressure evaporation treatment, S5: Oil outlet treatment, TC: Three-way catalyst (electrically heated catalyst), Vgi: Gas inlet valve, Vgo: Gas outlet valve, Voi: Oil inlet valve, Voo: Oil outlet valve, VP: Predetermined negative pressure.

Claims

1. A tank located outside or inside the crankcase of an internal combustion engine, A gas outlet passage for leading gas from the inside of the tank to the outside of the tank, An oil introduction passage for introducing lubricating oil from the oil pan of the internal combustion engine into the tank, A gas introduction passage for introducing gas from outside the tank into the tank, An oil outlet passage for discharging the lubricating oil from the tank to the oil pan, Solenoid valves provided in each of the gas outlet passage, the oil inlet passage, the gas inlet passage, and the oil outlet passage, The system includes a control unit that individually controls the opening and closing of the solenoid valves, The solenoid valve includes a gas outlet valve for opening and closing the gas outlet passage, an oil inlet valve for opening and closing the oil inlet passage, a gas inlet valve for opening and closing the gas inlet passage, and an oil outlet valve for opening and closing the oil outlet passage. The control unit sequentially performs the following processes: an oil introduction process in which lubricating oil is introduced from the oil pan to the tank by opening the gas outlet valve and the oil inlet valve and then closing the gas inlet valve and the oil outlet valve; a negative pressure evaporation process in which the gas outlet valve is opened and the oil inlet valve and the oil outlet valve are closed, and the gas inlet valve is opened and closed to maintain the internal pressure of the tank at a predetermined negative pressure; and an oil discharge process in which lubricating oil is discharged from the tank to the oil pan by closing the gas outlet valve and the oil inlet valve and then opening the gas inlet valve and the oil outlet valve. Lubricant dilution suppression device.

2. The tank further comprises a heating device for heating the lubricating oil inside the tank, The control unit controls the heating device in the negative pressure evaporation process to heat the lubricating oil to a predetermined temperature. The lubricating oil dilution suppression device according to claim 1.

3. The control unit performs the oil introduction process, the negative pressure evaporation process, and the oil discharge process when the vehicle equipped with the internal combustion engine is connected to an external power source. The lubricating oil dilution suppression device according to claim 1 or claim 2.

4. The control unit, in the negative pressure evaporation process, heats the electrically heated catalyst provided in the exhaust passage of the internal combustion engine when the vehicle is connected to the external power supply. The lubricating oil dilution suppression device according to claim 3.

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