Method for removing moisture in lubricating oil

Abstract

To provide a method for removing moisture in lubricating oil capable of removing moisture contained in the lubricating oil.SOLUTION: The method for removing moisture in lubricating oil removes moisture contained in lubricating oil supplied to an internal combustion engine. In the method for removing the moisture in the lubricant, it is determined whether or not the moisture contained in the lubricant O is frozen during the stop of the internal-combustion engine in a step S14, the lubricant O is heated in the step S15 when it is determined that the moisture is frozen, and the water melted by heating in the step S19 and separated from the lubricant O is discharged before the start of the internal-combustion engine.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for removing water from lubricating oil. [Background technology]

[0002] For example, an oil supply device for an internal combustion engine (hereinafter simply referred to as the "conventional device") is known from the past, as disclosed in Patent Document 1. The conventional device is equipped with a heater capable of heating oil near the mesh of an oil strainer that filters out solid matter contained in the oil, and when it is determined that water in the oil has frozen, the heater heats the oil, thereby preventing blockage or damage to the oil passage due to ice blocks. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-217258 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional devices melt ice blocks contained in the lubricating oil near the mesh. However, depending on the vehicle's operating conditions, such as repeated short-term driving in cold climates, the amount of water in the lubricating oil may increase. In this case, conventional devices may take a long time to melt the ice blocks and may not be able to separate the water from the lubricating oil, which may affect the lubrication of the internal combustion engine during cold starts.

[0005] An object of the present invention is to provide a method for removing water from lubricating oil, which is capable of removing water contained in lubricating oil. [Means for solving the problem]

[0006] The method for removing water from lubricating oil of the present invention is a method for removing water contained in lubricating oil supplied to an internal combustion engine, which determines whether the water is frozen while the internal combustion engine is stopped, and if it is determined that the water is frozen, heats the lubricating oil, and melts the water by heating while the internal combustion engine is stopped, separating it from the lubricating oil, and discharges it outside the internal combustion engine before starting the internal combustion engine. [Effects of the Invention]

[0007] According to the present invention, by melting the water frozen in the lubricating oil while the internal combustion engine is stopped, the lubricating oil and the water can be separated into layers. Then, in this state, the water separated from the lubricating oil can be discharged before the internal combustion engine is started. This allows the internal combustion engine to be operated by supplying lubricating oil with reduced water content, thereby maintaining the lubrication of the lubricating oil inside the internal combustion engine during cold start. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic cross-sectional view of an internal combustion engine according to an embodiment of the present invention; [Figure 2] 10 is a flowchart of a moisture removal control program. [Figure 3] FIG. 2 is a diagram for explaining the change in state of moisture (water) in lubricating oil during moisture removal. DETAILED DESCRIPTION OF THE INVENTION

[0009] The method for removing water from lubricating oil of the present invention (hereinafter sometimes simply referred to as the "water removal method") will be described in detail below with reference to the drawings. The water removal method can be applied to an internal combustion engine 1 shown in FIG. 1. The internal combustion engine 1 includes a cylinder block 12 in which, for example, four cylinders 11 are aligned in a row, and a cylinder head 13 attached to the top of the cylinder block 12. Note that FIG. 1 shows only one cylinder 11. A piston 14 is inserted into each cylinder 11 so that it can reciprocate, and is connected to a crankshaft 16 via a connecting rod 15.

[0010] The internal combustion engine 1 also has an oil pan 17 attached to the bottom of the cylinder block 12, which stores lubricating oil O. As a result, in the internal combustion engine 1, the bottom of the cylinder block 12 and the oil pan 17 form a crankcase 18 that houses the crankshaft 16. An oil temperature sensor 71 is disposed at the bottom of the oil pan 17. A crank position sensor 72 is disposed inside the crankcase 18. A water temperature sensor 73 is also disposed on the side wall of the cylinder block 12.

[0011] An oil pump 19 driven by the crankshaft 16 via a chain or the like is disposed inside the crankcase 18. The oil pump 19 draws up lubricating oil O stored in the oil pan 17 via an oil strainer 19A and supplies the lubricating oil O to each lubricated part of the internal combustion engine 1, such as the piston 14 and the bearings of the crankshaft 16. The oil strainer 19A is provided with a mesh (not shown) to separate foreign matter from the drawn lubricating oil as it flows.

[0012] A lubricating oil heater 2 is disposed inside the oil pan 17 to heat the lubricating oil O pumped up by the oil pump 19 and to dissolve frozen water contained in the lubricating oil O. The lubricating oil heater 2 is energized and controlled by an electronic control unit 8, which will be described later, and heats the lubricating oil O stored in the oil pan 17 while the internal combustion engine 1 is stopped.

[0013] A drain 17A is provided at the bottom of the oil pan 17. The drain 17A is controlled by the electronic control unit 8 and, as will be described later, discharges moisture (water) that has separated into layers inside the oil pan 17 to the outside. In this embodiment, the drain 17A is provided at the bottom of the oil pan 17. Alternatively, for example, a partition wall may be provided inside the oil pan 17 to allow water that sinks below the lubricating oil O due to the difference in specific gravity between the lubricating oil O and water to pass through and separate the water from the lubricating oil O.

[0014] In the internal combustion engine 1 of this embodiment, a spark plug 3 is disposed on the underside of a cylinder head 13 located on top of the cylinder block 12, corresponding to each cylinder 11. An intake port 40, which is the downstream end of an intake passage 4, and an exhaust port 50, which is the upstream end of an exhaust passage 5, are opened on the underside of the cylinder head 13. An intake valve 41 and an exhaust valve 51 are disposed in the intake port 40 and the exhaust port 50, respectively, and are opened and closed by an intake camshaft 42 and an exhaust camshaft 52 of a valve train.

[0015] In the intake passage 4, a throttle valve 43 and a surge tank 44 are disposed downstream of an air cleaner (not shown), and an intake manifold 45 is connected downstream of the surge tank 44. An air flow meter 74 and a throttle opening sensor 75 are also disposed in the intake passage 4.

[0016] Meanwhile, an exhaust manifold 53 is disposed in the exhaust passage 5 to collect the exhaust ports 50 of each cylinder 11. A catalyst 54, such as a three-way catalyst, for purifying the exhaust gas is disposed downstream of the exhaust manifold 53. An air-fuel ratio sensor 76 is disposed upstream of the catalyst 54, and an oxygen sensor 77 is disposed downstream of the catalyst 54.

[0017] In addition, the internal combustion engine 1 of this embodiment is provided with an injector 6 disposed on the periphery of the intake side of each cylinder 11. The injector 6 injects fuel from the intake stroke to the compression stroke of the internal combustion engine 1. As a result, an air-fuel mixture is formed in the cylinder 11 by the end of the compression stroke, and the spark plug 3 receives high voltage from the igniter 31 and ignites the air-fuel mixture. A fuel supply system to the injector 6 is formed by a fuel tank 61, a fuel supply pipe 62, a high-pressure fuel pump 63, etc.

[0018] The electronic control unit 8 (hereinafter sometimes referred to as "ECU 8") has as its main components a microcomputer having a CPU, ROM, RAM, and various interfaces. The CPU executes various calculation processes based on various control programs and maps, including the programs described below, stored in the ROM. The RAM temporarily stores the results of calculations performed by the CPU and various data. The ECU 8 also has a non-volatile backup RAM, which stores, for example, data to be saved when the internal combustion engine 1 is stopped as backup data.

[0019] The ECU 8 is connected via an interface to the above-mentioned oil temperature sensor 71, crank position sensor 72, water temperature sensor 73, air flow meter 74, throttle opening sensor 75, air-fuel ratio sensor 76, oxygen sensor 77, etc. The ECU 8 is also connected to an accelerator opening sensor 78 that detects the amount of operation of an accelerator pedal (not shown), i.e., the accelerator opening.

[0020] The ECU 8 executes various control programs based on signals input from the various sensors described above, thereby controlling the operation of the internal combustion engine 1. Specifically, the ECU 8 calculates a target torque for the internal combustion engine 1 based on the accelerator opening, the load factor and rotation speed of the internal combustion engine 1, or the vehicle speed, and controls the ignition timing by the spark plug 3, the fuel injection by the injector 6, and the throttle opening, i.e., the intake amount, so as to output this target torque.

[0021] 2 based on signals input from the various sensors described above, thereby removing moisture (water) contained in the lubricating oil O while the internal combustion engine 1 is stopped. The moisture removal program that realizes the moisture removal method will be specifically described below.

[0022] In the internal combustion engine 1, during the compression stroke or the combustion stroke, part of the air-fuel mixture may become so-called blow-by gas and be blown through and discharged into the crankcase 18. In this case, while the internal combustion engine 1 is stopped, water vapor contained in the blow-by gas may condense, for example, as the temperature inside the crankcase 18 drops, and as a result, water may be mixed into the lubricating oil O stored in the oil pan 17.

[0023] As shown in FIG. 3(A), the moisture mixed in the lubricating oil O is dispersed in the lubricating oil O while the internal combustion engine 1 is stopped. In cold regions, for example, the moisture dispersed in the lubricating oil O may freeze into ice blocks while the internal combustion engine 1 is stopped, as shown in FIG. 3(B). When the ice blocks dispersed in the lubricating oil O are melted, the lubricating oil O, which has a lower specific gravity, floats on the water due to the difference in specific gravity between the lubricating oil O and water, i.e., the water, which has a higher specific gravity, sinks in the lubricating oil O, causing some of the moisture (water) produced by the melting to separate in layers from the lubricating oil O, as shown in FIG. 3(C).

[0024] That is, while the internal combustion engine 1 is stopped, the water mixed in the lubricating oil O freezes and the ice blocks formed by the freezing are melted repeatedly, thereby separating the water (water) mixed in the lubricating oil O into layers, and the separated water (water) can be removed. Therefore, in this embodiment, the ECU 8 executes a water removal program shown in FIG. 2 so that the water in the lubricating oil O is separated into layers by repeated freezing and thawing. By executing the water removal program in this manner, the internal combustion engine 1 can be operated by supplying lubricating oil O with reduced water content, thereby maintaining the lubrication of the inside of the internal combustion engine 1 by the lubricating oil O during cold start.

[0025] The ECU 8 starts executing the program in step S10 when the internal combustion engine 1 is stopped, for example, based on the detection values ​​of the crank position sensor 72, the air flow meter 74, the throttle opening sensor 75, the air-fuel ratio sensor 76, the oxygen sensor 77, and the accelerator opening sensor 78. Then, in the following step S11, the ECU 8 estimates the amount of water mixed into the lubricating oil O, i.e., the amount of water in the oil W.

[0026] That is, the ECU 8 estimates the amount of water in oil based on, for example, the amount of blow-by gas generated inside the internal combustion engine 1. That is, the amount of blow-by gas generated inside the internal combustion engine 1 can be determined based on the burned air, i.e., the amount of intake air detected by the air flow meter 74. Therefore, the ECU 8, for example, calculates the total intake air amount by integrating the intake air amount during cold operation of the internal combustion engine 1 detected by the air flow meter 74, and estimates the amount of water in oil W based on the total intake air amount. Note that, although the present embodiment illustrates an example in which the amount of water in oil W is estimated, it is also possible to implement the method in which the amount of water in oil W is measured directly or indirectly. Then, once the ECU 8 has estimated the amount of water in oil W, it executes the step processing of step S12.

[0027] In step S12, the ECU 8 determines whether the estimated amount of water in the oil W is equal to or greater than a predetermined threshold value Wb. That is, if the amount of water in the oil W is equal to or greater than the threshold value Wb, the ECU 8 determines "Yes" because it is necessary to remove the water mixed into the lubricating oil O, and executes the processing of each step from step S13 onwards. On the other hand, if the amount of water in the oil W is less than the threshold value Wb, the ECU 8 determines "No" because it is not yet necessary to remove the water mixed into the lubricating oil O, and ends the execution of the water removal program in step S20.

[0028] In step S13, the ECU 8 acquires the oil temperature T of the lubricating oil O stored in the oil pan 17 from the oil temperature sensor 71, and executes the step processing of step S14. Note that, instead of or in addition to directly measuring and acquiring the oil temperature T by the oil temperature sensor 71, the oil temperature T can also be estimated based on the water temperature acquired from the water temperature sensor 73.

[0029] In step S14, the ECU 8 determines whether or not the moisture (water) mixed in the lubricating oil O is frozen based on the acquired oil temperature T. That is, if the oil temperature T is below 0 degrees Celsius and below a set first determination temperature T1, the ECU 8 determines "Yes" because the moisture (water) is frozen (is likely to be frozen), that is, ice blocks are dispersed in the lubricating oil O, and executes the step processing of step S15. On the other hand, if the oil temperature T is equal to or higher than the first determination temperature T1, the ECU 8 determines "No" because the moisture (water) is not frozen (is likely to be not frozen), and ends the execution of the moisture removal program in step S20.

[0030] In step S15, the ECU 8 heats the lubricating oil O. Specifically, the ECU 8 controls the supply of electricity to the lubricating oil heater 2 to cause the lubricating oil heater 2 to generate heat and heat the lubricating oil O stored in the oil pan 17. In the following step S16, the ECU 8 acquires the oil temperature T of the lubricating oil O stored in the oil pan 17 from the oil temperature sensor 71, and executes the step processing of step S17.

[0031] In step S17, the ECU 8 determines whether the ice blocks dispersed in the lubricating oil O have melted based on the acquired oil temperature T. That is, if the oil temperature T is equal to or higher than a second determination temperature T2 set at 0 degrees Celsius or higher, the ECU 8 determines "Yes" because the ice blocks have melted (are likely to have melted), and executes the step processing of step S18. On the other hand, if the oil temperature T is lower than the second determination temperature T2, the ECU 8 determines "No" because the ice blocks have not melted (are likely to have not melted), and executes the step processing from step S15 onwards.

[0032] In step S18, the ECU 8 stops heating the lubricating oil O. Specifically, the ECU 8 controls the supply of current to the lubricating oil heater 2 to stop the lubricating oil heater 2 from generating heat, thereby stopping the heating of the lubricating oil O stored in the oil pan 17.

[0033] In the next step S19, the ECU 8 drains (or isolates) the water (water) that has separated into layers inside the oil pan 17 while the internal combustion engine 1 is stopped, in other words, before the internal combustion engine 1 is started. Specifically, the ECU 8 controls the flow of current to open the drain 17A, thereby discharging the water (water) that has separated into layers at the bottom of the oil pan 17 to the outside of the internal combustion engine 1. In this case, the ECU 8 can, for example, intermittently open and close the drain 17A for a predetermined period of time to drain the separated water (water), or open and close the drain 17A in response to a change in viscosity of the liquid passing through the drain 17A to drain the separated water (water). In addition, when the water (water) that has separated into layers is isolated via a partition wall, the water (water) can be drained at a certain frequency, for example, by loosening a drain bolt disposed at the bottom of the oil pan 17.

[0034] Then, after discharging the moisture (water) separated into layers in step S19, the ECU 8 returns to the step processing of step S11 and repeatedly executes the step processing from step S11 onwards, for example, until the internal combustion engine 1 is started. Note that the ECU 8 is configured to subtract the amount of water discharged from the amount of water in the oil W when executing the step processing of step S11 for the second time or later, based on the relationship, which can be determined experimentally, with the amount of water separated when a single cycle of freezing and thawing is performed when the amount of water in the oil is W.

[0035] As can be understood from the above explanation, the method for removing water from lubricating oil removes water contained in lubricating oil O supplied to the internal combustion engine 1. The method for removing water from lubricating oil determines whether or not the water is frozen while the internal combustion engine 1 is stopped, and if it is determined that the water is frozen, heats the lubricating oil O, and melts the water by heating while the internal combustion engine 1 is stopped, and discharges the water that is separated from the lubricating oil O to the outside of the internal combustion engine 1 before the internal combustion engine 1 is started.

[0036] This allows the water frozen in the lubricating oil O to melt while the internal combustion engine 1 is stopped, or more preferably, allows repeated freezing and melting, resulting in a state in which the lubricating oil O and water are separated into layers. In this state, the water separated from the lubricating oil O can be discharged before starting the internal combustion engine 1. This allows the internal combustion engine 1 to be operated by supplying lubricating oil O with reduced water content, thereby maintaining the lubrication of the inside of the internal combustion engine 1 by the lubricating oil O during cold start. [Explanation of symbols]

[0037] 1...internal combustion engine, 17...oil pan, 17A...drain, 2...lubricating oil heater, 71...oil temperature sensor, 8...electronic control unit, O...lubricating oil, W...water content in oil, Wb...threshold value, T...oil temperature, T1...first judgment temperature, T2...second judgment temperature

Claims

[Claim 1] A method for removing water contained in lubricating oil supplied to an internal combustion engine, comprising: determining whether the water is frozen while the internal combustion engine is stopped; heating the lubricating oil when it is determined that the water is frozen; A method for removing water from lubricating oil, comprising heating the lubricating oil while the internal combustion engine is stopped to melt and separate the water from the lubricating oil, and discharging the water outside the internal combustion engine before starting the internal combustion engine.

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