Internal combustion engine

Abstract

The present invention provides an internal combustion engine that can suppress clogging of the oil inflow path due to the strainer sucking in emulsion, and the occurrence of airlocks due to the strainer sucking in air. [Solution] The distance between the first intake port and the lowest part of the oil pan in the vertical direction is greater than the distance between the second intake port and the lowest part in the vertical direction. The valve position of the flow path switching valve is switchable between a first position that connects the first intake port and the oil pump and blocks communication between the second intake port and the oil pump, and a second position that blocks communication between the first intake port and the oil pump and connects the second intake port and the oil pump. The control device switches the valve position to the first position when the oil pump starts operating (S11-S12), and switches the valve position to the second position after the internal combustion engine has finished warming up (S13-S14).

Description

Technical Field

[0001] This invention relates to an internal combustion engine.

Background Art

[0002] Patent Document 1 discloses a strainer for sucking oil stored in an oil pan of an internal combustion engine and feeding it into an oil pump.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, water may be mixed into the oil in the oil pan. When the oil and water are stirred by an oil pump, an emulsion having a higher viscosity than the oil is generated. Since the emulsion has a greater specific gravity than the oil, it precipitates at the bottom of the oil pan. In a low-temperature environment, this emulsion may freeze.

[0005] When the operation of the oil pump is restarted, the frozen emulsion may be sucked by the strainer, resulting in clogging of the oil inflow path. Since the emulsion precipitates at the bottom of the oil pan, increasing the distance between the suction port of the strainer and the bottom of the oil pan makes it difficult for the strainer to suck in the emulsion. By suppressing the suction of the emulsion, clogging of the oil inflow path due to the frozen emulsion is less likely to occur.

[0006] On the other hand, in internal combustion engines installed in vehicles, the oil level tilts, exposing the strainer's intake port to the air, which causes air to mix with the oil flowing through the intake path (hereinafter referred to as airlock). Increasing the distance between the strainer's intake port and the bottom of the oil pan to suppress the intake of emulsions makes the strainer's intake port more easily exposed to the air, thus making airlock more likely to occur. [Means for solving the problem]

[0007] An internal combustion engine for solving the above problems is an in-vehicle internal combustion engine comprising an oil pan, an oil pump, and a strainer for supplying oil from the oil pan to the oil pump, further comprising an energized flow path switching valve and a control device for controlling the flow path switching valve, wherein the strainer includes a first pipe having a first suction port located in the oil pan and connected to the oil pump, and a second pipe having a second suction port located in the oil pan and connected to the oil pump, wherein the distance between the first suction port and the lowest part of the oil pan in the vertical direction is greater than the distance between the second suction port and the lowest part in the vertical direction, and the flow path switching valve The valve position is switchable between a first position that connects the first suction port and the oil pump and blocks communication between the second suction port and the oil pump, and a second position that blocks communication between the first suction port and the oil pump and connects the second suction port and the oil pump. The control device performs a first switching process to control the flow path switching valve so that the valve position switches from the second position to the first position when either the operation of the oil pump is started or the operation of the oil pump is stopped, and a second switching process to control the flow path switching valve so that the valve position switches from the first position to the second position after the warm-up of the internal combustion engine is complete. [Effects of the Invention]

[0008] The above-described internal combustion engine can suppress clogging of the oil inflow path due to the strainer sucking in emulsion, and the occurrence of airlocks due to the strainer sucking in air. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic diagram of an internal combustion engine according to one embodiment. [Figure 2] Figure 2 is a flowchart showing the processing performed by the control device of the first embodiment. [Figure 3] Figure 3 is a flowchart showing the processing performed by the control device of the second embodiment. [Modes for carrying out the invention]

[0010] <First Embodiment> The first embodiment of the internal combustion engine will be described below with reference to Figures 1 and 2. <Configuration of an internal combustion engine> The vehicle is equipped with an internal combustion engine 10. The internal combustion engine 10 shown in Figure 1 is an on-board internal combustion engine installed in the vehicle. The internal combustion engine 10 is used, for example, as a power source for the vehicle. The fuel for the internal combustion engine 10 is, for example, hydrogen.

[0011] The internal combustion engine 10 includes a cylinder as a combustion chamber for burning a fuel-air mixture. The internal combustion engine 10 also includes a piston that reciprocates within the combustion chamber, an output shaft that outputs rotational torque, and a connecting rod that connects the piston and the output shaft. When the internal combustion engine 10 is in operation, hydrogen as fuel is injected into the combustion chamber, and the piston reciprocates due to the combustion of the fuel within the combustion chamber. The reciprocating motion of the piston is converted into rotational motion of the output shaft by the connecting rod and the output shaft.

[0012] The internal combustion engine 10 comprises an oil pan 21, an oil pump 22, and a strainer 23. The oil pan 21 is located on the underside of the internal combustion engine 10. The oil pan 21 stores oil L. In the example shown in Figure 1, the oil pan 21 has a first case 24 and a second case 25. The first case 24 constitutes the lowest part 21L of the oil pan 21 in the vertical direction. The second case 25 is fixed above the first case 24. The second case 25 constitutes the highest part 21H of the oil pan 21 in the vertical direction.

[0013] The oil pump 22 is, for example, a pump driven by the rotational force of the output shaft. In this case, for example, pulleys are attached to both the oil pump 22 and the output shaft. Belts are wrapped around these pulleys. The rotational force of the output shaft is transmitted to the oil pump 22 via the belt. The oil pump 22 is, for example, a pump driven by an electric motor.

[0014] The oil pump 22 draws up oil L from the oil pan 21 via the strainer 23. The oil L drawn up by the oil pump 22 is supplied to the supply section 12. The supply section 12 is, for example, a drive part that generates friction during the operation of the internal combustion engine 10, such as the piston, connecting rod, and output shaft mentioned above, or a hydraulic system that is operated by hydraulic pressure. After circulating through the supply section 12 for purposes such as lubrication, the oil L flows into the oil pan 21.

[0015] The strainer 23 sends the oil L in the oil pan 21 to the oil pump 22. The strainer 23 includes an intake pipe 26. One end of the intake pipe 26 is connected to the oil pump 22. The other end of the intake pipe 26 branches into a first pipe 27 and a second pipe 28.

[0016] The strainer 23 includes a first pipe 27 and a second pipe 28. The first pipe 27 is connected to the oil pump 22. The first pipe 27 is connected to the oil pump 22 via, for example, the suction pipe 26. The first pipe 27 has a first suction port 29. The first suction port 29 is disposed in the oil pan 21. When at least the vehicle is stationary, the first suction port 29 is immersed in the oil L.

[0017] The second pipe 28 is connected to the oil pump 22. The second pipe 28 is connected to the oil pump 22 via, for example, the suction pipe 26. The second pipe 28 has a second suction port 31. The second suction port 31 is disposed in the oil pan 21. The second suction port 3l is immersed in the oil L.

[0018] The first suction port 29 is located above the second suction port 31 in the vertical direction. A first distance L1, which is the distance between the first suction port 29 and the lowest part 21L of the oil pan 21 in the vertical direction, is greater than a second distance L2, which is the distance between the second suction port 31 and the lowest part 21L in the vertical direction. Preferably, when a third distance L3 from the lowest part 21L to the highest part 21H of the oil pan 21 is h, the first distance L1 is h / 5 or more. The second distance L2 is less than h / 5.

[0019] The internal combustion engine 10 further includes a flow path switching valve 40 and a control device 50. The flow path switching valve 40 operates by being energized. The flow path switching valve 40 is, for example, a solenoid valve. The flow path switching valve 40 is disposed between the suction pipe 26 and the first pipe 27 and the second pipe 28.

[0020] The valve position of the flow path switching valve 40 can be switched between a first position and a second position. The first position is a position where the first suction port 29 and the oil pump 22 are in communication and the communication between the second suction port 31 and the oil pump 22 is blocked. When the valve position of the flow path switching valve 40 is the first position, the oil pump 22, the suction pipe 26, and the first pipe 27 are in communication. When the valve position of the flow path switching valve 40 is the first position, the oil pump 22 sucks oil L from the first suction port 29. The second position is a position where the communication between the first suction port 29 and the oil pump 22 is blocked and the second suction port 31 and the oil pump 22 are in communication. When the valve position of the flow path switching valve 40 is the second position, the oil pump 22, the suction pipe 26, and the second pipe 28 are in communication. When the valve position of the flow path switching valve 40 is the second position, the oil pump 22 sucks oil L from the second suction port 31.

[0021] The control device 50 includes a processing circuit and a storage device not shown in the figure. The processing circuit is composed of a CPU that executes processing according to a program and its peripheral circuits. The storage device is composed of a ROM in which a program is stored, a volatile RAM into which data can be temporarily written, a non-volatile storage into which data can be written, and the like. The storage device stores information related to the control of the internal combustion engine 10.

[0022] The control device 50 controls the flow path switching valve 40. For example, the control device 50 controls the valve position of the flow path switching valve 40 by outputting a control signal indicating the valve position of the flow path switching valve 40 to the flow path switching valve 40.

[0023] The internal combustion engine 10 includes, for example, an oil temperature acquisition unit 51, a discharge pressure acquisition unit 52, an elapsed time acquisition unit 53, and a moisture content acquisition unit 54. Each of the oil temperature acquisition unit 51, the discharge pressure acquisition unit 52, the elapsed time acquisition unit 53, and the moisture content acquisition unit 54 outputs the acquisition result to the control device 50.

[0024] The oil temperature acquisition unit 51 acquires the oil temperature LT of the oil L in the oil pan 21. The oil temperature acquisition unit 51 includes, for example, an oil temperature sensor. The discharge pressure acquisition unit 52 acquires the discharge pressure DP of the oil pump 22. The discharge pressure acquisition unit 52 includes, for example, a hydraulic sensor.

[0025] The elapsed time acquisition unit 53 acquires the elapsed time ED from the start of operation of the oil pump 22 until the discharge pressure DP of the oil pump 22 rises to a predetermined pressure. The elapsed time acquisition unit 53 includes, for example, a timer. The elapsed time acquisition unit 53 may also be a function of the control device 50.

[0026] The moisture content acquisition unit 54 acquires the moisture content MC of the oil L in the oil pan 21. The moisture content acquisition unit 54 includes, for example, a sensor that detects the moisture content MC of the oil L. An example of a sensor that detects the moisture content MC is a capacitive sensor.

[0027] The oil L in the oil pan 21 and the water mixed in the oil pan 21 are agitated by the oil pump 22, generating an emulsion M with a higher viscosity than the oil L. The emulsion M that settles at the bottom of the oil pan 21 may freeze in low-temperature environments. Frozen emulsion M has a higher water content MC than unfrozen emulsion M. When hydrogen is used as fuel for the internal combustion engine 10, the amount of water mixed into the oil L is greater than when gasoline is used as fuel because the combustion gas contains a large amount of water.

[0028] Because the emulsion M has a higher water content MC compared to the oil L, it settles at the bottom of the oil pan 21. Preferably, the water content acquisition unit 54 is configured to acquire the water content MC at the bottom of the oil pan 21. When the water content MC detected by the sensor of the water content acquisition unit 54 is high, it is more likely than when the water content MC is low that emulsion M has settled at the bottom of the oil pan 21, or that the settled emulsion M has frozen. When the operation of the internal combustion engine 10 is started, the oil L circulates between the oil pan 21 and the oil supply part 12. Since the temperature of the supply part 12 is higher than the oil temperature LT of the oil L in the oil pan 21, the frozen emulsion M melts as the temperature of the oil L in the oil pan 21 rises.

[0029] <Processing by the control device> The control device 50 performs a first switching process and a second switching process. The first switching process is a process of controlling the flow path switching valve 40 so that the valve position of the flow path switching valve 40 switches from the second position to the first position. The control device 50 performs the first switching process when the operation of the oil pump 22 is started. The operation of the oil pump 22 starts, for example, when the internal combustion engine 10 starts operation. In the first switching process, the control device 50 outputs a control signal to the flow path switching valve 40 so that the valve position of the flow path switching valve 40 switches from the second position to the first position.

[0030] The second switching process is a process of controlling the flow path switching valve 40 so that the valve position of the flow path switching valve 40 switches from the first position to the second position. The control device 50 executes the second switching process after the internal combustion engine 10 has finished warming up. The control device 50 determines that the internal combustion engine 10 has finished warming up, for example, based on the fact that the oil temperature LT of the oil L has reached a predetermined temperature. The control device 50 determines that the warm-up has finished, for example, based on the fact that the coolant temperature of the internal combustion engine 10 has reached a predetermined temperature. In the second switching process, the control device 50 outputs a control signal to the flow path switching valve 40 so that the valve position of the flow path switching valve 40 switches from the first position to the second position.

[0031] Figure 2 shows a sequence of processes performed by the control device 50 of this embodiment. The control device 50 repeatedly executes the processes shown in Figure 2.

[0032] In step S11, the control device 50 determines whether or not the oil pump 22 has started operating. For example, the control device 50 determines that the oil pump 22 has started operating when the internal combustion engine 10 has started operating. If the control device 50 determines that the oil pump 22 has started operating (step S11: YES), it executes the process in step S12. If the control device 50 determines that the oil pump 22 has not started operating (step S11: NO), it terminates the process shown in Figure 2.

[0033] The control device 50 executes the first switching process in step S12, and then executes the process in step S13. In step S13, the control device 50 determines whether the warm-up of the internal combustion engine 10 is complete. For example, the control device 50 determines that the warm-up of the internal combustion engine 10 is complete if the oil temperature LT of the oil L in the oil pan 21 is equal to or greater than the third predetermined value PV3. The control device 50 obtains the oil temperature LT from the oil temperature acquisition unit 51. If the control device 50 determines that the warm-up of the internal combustion engine 10 is complete (step S13: YES), it executes the process in step S14. If the control device 50 determines that the warm-up of the internal combustion engine 10 is not complete (step S13: NO), it repeats the process in step S13.

[0034] After executing the second switching process in step S14, the control device 50 terminates the process shown in Figure 2. <Operation and Effects of This Embodiment> (1) If the internal combustion engine 10 has not finished warming up, the control device 50 outputs a control signal to the flow path switching valve 40 to set the valve position of the flow path switching valve 40 to the first position. Because the first distance L1 is greater than the second distance L2, the first intake port 29 is less likely to suck in the frozen emulsion M settled at the bottom of the oil pan 21. As a result, clogging of the emulsion M in the oil L inflow path is less likely to occur.

[0035] After the internal combustion engine 10 has finished warming up, the control device 50 outputs a control signal to the flow path switching valve 40 to set the valve position of the flow path switching valve 40 to the second position. After the internal combustion engine 10 has finished warming up, there is a high possibility that the frozen emulsion M has melted, so clogging of the oil L inflow path with emulsion M is unlikely to occur. Since the second distance L2 is smaller than the first distance L1, exposure of the second intake port 31 to the air due to the tilting of the oil level is less likely to occur than exposure of the first intake port 29 to the air due to the tilting of the oil level. When oil L is drawn in from the second intake port 31, airlock is less likely to occur compared to when oil L is drawn in from the first intake port 29. According to this embodiment, clogging of the oil L inflow path due to the strainer 23 drawing in emulsion M and the occurrence of airlock due to the strainer 23 drawing in air can be suppressed.

[0036] <Second Embodiment> The second embodiment of the internal combustion engine will be described below with reference to Figures 1 and 3. The same configuration and operation as in the first embodiment will be simplified or omitted from the description. In the second embodiment, the conditions for executing the first and second switching processes differ from those in the first embodiment.

[0037] <Processing by the control device> The control device 50 of this embodiment performs a first determination process and a first switching process. The first determination process is a process that determines whether the elapsed period ED from the start of operation of the oil pump 22 until the discharge pressure DP of the oil pump 22 rises to a first predetermined value PV1 is equal to or greater than a predetermined period PD. The first predetermined value PV1 is set, for example, to the discharge pressure DP when the oil pump 22 is in normal operation. Normal operation of the oil pump 22 is the operation of the oil pump 22 in a state in which there is no blockage of emulsion M in the oil L inflow path. The first predetermined value PV1 is, for example, 200 kPa. The predetermined period PD is set, for example, to the time until the oil pump 22 starts up when there is no blockage of emulsion M in the oil L inflow path. The predetermined period PD is, for example, 1 sec. The control device 50 performs the first determination process when the valve position of the flow path switching valve 40 is in the second position.

[0038] Preferably, in the first determination process, the control device 50 further determines whether the rate of change CR of the discharge pressure DP per unit time is greater than or equal to a second predetermined value PV2. The rate of change CR is calculated as (XY) / X when the discharge pressure DP at the first time is X kPa and the discharge pressure DP at the second time, one unit time after the first time, is Y kPa. The second predetermined value PV2 is set to a value that indicates, for example, that a blockage of emulsion M has occurred in the inflow path of oil L. The second predetermined value PV2 is, for example, 10 percent.

[0039] In this specification, the change rate CR being greater than or equal to a second predetermined value PV2 includes the condition that the change rate CR is greater than or equal to a second predetermined value PV2 when the change rate CR is a positive value, and that the change rate CR is less than or equal to minus a second predetermined value PV2 when the change rate CR is a negative value. When the discharge pressure DP at the second time point falls below the discharge pressure DP at the first time point due to the emulsion M clogging the inflow path of the oil L, the change rate CR becomes a positive value.

[0040] On the other hand, when the emulsion M flows into the oil pump 22, the shear force of the oil pump 22 acts on the emulsion M, which may cause the emulsion M to separate into oil L and water. For example, when the discharge pressure DP decreases due to the emulsion M clogging the oil L inflow path, the clogging is cleared when the emulsion M separates into oil L and water. As a result, the discharge pressure DP at the second time step increases compared to the discharge pressure DP at the first time step. When the emulsion M clogging the oil L inflow path separates, the rate of change CR becomes a negative value.

[0041] In this embodiment, the control device 50 makes a positive determination in the first determination process when the elapsed period ED is equal to or greater than a predetermined period PD and the rate of change CR is equal to or greater than a second predetermined value PV2. When the control device 50 makes a positive determination in the first determination process, it executes the first switching process. Even if the operation of the oil pump 22 is started, the control device 50 does not execute the first switching process if the first determination process makes a negative determination.

[0042] The control device 50 of this embodiment performs a second determination process and a second switching process. The second determination process is a process of determining whether the oil temperature LT of the oil L in the oil pan 21 is equal to or greater than a third predetermined value PV3. The third predetermined value PV3 is set, for example, to the melting temperature of the emulsion M frozen in the oil pan 21. The third predetermined value PV3 is, for example, 100°C. The control device 50 performs the second determination process when the valve position of the flow path switching valve 40 is in the first position.

[0043] Preferably, in the second determination process, the control device 50 further determines whether the moisture content MC of the oil L at the bottom of the oil pan 21 is less than a fourth predetermined value PV4. The fourth predetermined value PV4 is set to a value that indicates, for example, that the water in the oil pan 21 has evaporated. The fourth predetermined value PV4 is, for example, 5%.

[0044] In this embodiment, the control device 50 makes a positive determination in the second determination process when the oil temperature LT is equal to or greater than the third predetermined value PV3 and the moisture content MC is less than the fourth predetermined value PV4. When the control device 50 makes a positive determination in the second determination process, it executes the second switching process. In this embodiment, the control device 50 does not execute the second switching process if the second determination process makes a negative determination, regardless of whether the internal combustion engine 10 has completed warming up.

[0045] Figure 3 shows a series of processes executed by the control device 50 of this embodiment. In Figure 3, steps S22 and S23 correspond to the first determination process. Steps S25 and S26 correspond to the second determination process. The control device 50 repeatedly executes the process shown in Figure 3 when the valve position of the flow path switching valve 40 is in the second position. Note that a detailed explanation of the parts that are common with the process shown in Figure 2 of the first embodiment is omitted.

[0046] In step S21, the control device 50 determines whether or not the oil pump 22 has started operating. If the oil pump 22 has started operating (step S21: YES), the control device 50 executes the process in step S22. If the oil pump 22 has not started operating (step S21: NO), the control device 50 terminates the process shown in Figure 3.

[0047] In step S22, the control device 50 determines whether the elapsed period ED from the start of operation of the oil pump 22 until the discharge pressure DP of the oil pump 22 rises to a first predetermined value PV1 is equal to or greater than a predetermined period PD. The control device 50 obtains the elapsed period ED from the elapsed period acquisition unit 53. The elapsed period acquisition unit 53 starts measuring the elapsed period ED, for example, according to the output of the discharge pressure acquisition unit 52. If the elapsed period ED is equal to or greater than the predetermined period PD (step S22: YES), the control device 50 executes the process in step S23. If the elapsed period ED is not equal to or greater than the predetermined period PD (step S22: NO), the control device 50 terminates the process shown in Figure 3.

[0048] In step S23, the control device 50 determines whether the rate of change CR of the discharge pressure DP per unit time is greater than or equal to a second predetermined value PV2. The control device 50 obtains the rate of change CR from the change in output of the discharge pressure acquisition unit 52. If the rate of change CR is greater than or equal to the second predetermined value PV2 (step S23: YES), the control device 50 executes the process in step S24. If the rate of change CR is not greater than or equal to the second predetermined value PV2 (step S23: NO), the control device 50 terminates the process shown in Figure 3.

[0049] The control device 50 executes the first switching process in step S24, and then executes the process in step S25. In step S25, the control device 50 determines whether the oil temperature LT of the oil L in the oil pan 21 is equal to or greater than a third predetermined value PV3. The control device 50 obtains the oil temperature LT from the oil temperature acquisition unit 51. If the oil temperature LT is equal to or greater than the third predetermined value PV3 (step S25: YES), the control device 50 executes the process in step S26. If the oil temperature LT is not equal to or greater than the third predetermined value PV3 (step S25: NO), the control device 50 repeats the process in step S25.

[0050] In step S26, the control device 50 determines whether the moisture content MC of the oil L at the bottom of the oil pan 21 is less than a fourth predetermined value PV4. The control device 50 obtains the rate of change CR from the moisture content acquisition unit 54. If the moisture content MC is less than the fourth predetermined value PV4 (step S26: YES), the control device 50 executes the process in step S27. If the moisture content MC is not less than the fourth predetermined value PV4 (step S26: NO), the control device 50 repeats the process from step S25.

[0051] After executing the second switching process in step S27, the control device 50 terminates the process shown in Figure 3. <Operation and Effects of This Embodiment> The operation and effects of this embodiment will now be explained.

[0052] (2-1) If frozen emulsion M clogs the oil L inflow path, the oil pump 22 will have difficulty pumping up the oil L. As a result, the elapsed time ED from the start of operation of the oil pump 22 until the discharge pressure DP of the oil pump 22 rises to a first predetermined value PV1 will be longer. When the elapsed time ED is longer than or equal to a predetermined period PD, the control device 50 outputs a control signal to the flow path switching valve 40 to set the valve position of the flow path switching valve 40 to the first position. As a result, oil L is drawn in from the first suction port 29, and the occurrence of clogging of the oil L inflow path by emulsion M can be suppressed.

[0053] (2-2) Fluctuations in the discharge pressure DP are likely to occur when the inflow path of the oil L becomes clogged with emulsion M. In this regard, the control device 50, in the first determination process, does not execute the first switching process if the rate of change CR of the discharge pressure DP per unit time is less than the second predetermined value PV2, even if the elapsed period ED is equal to or greater than the predetermined period PD. As a result, the control device 50 executes the first switching process when there is a higher probability that the inflow path of the oil L is clogged. Therefore, the first switching process is executed when there is no clog in the inflow path of the oil L, which can prevent airlock from occurring.

[0054] (2-3) When the oil L temperature LT of the oil L rises to the third predetermined value PV3 due to the operation of the oil pump 22 as the oil L circulates between the oil pan 21 and the supply section 12, it is highly likely that the frozen emulsion M is melting. When the oil temperature LT reaches or exceeds the third predetermined value PV3, the control device 50 outputs a control signal to the flow path switching valve 40 to set the valve position of the flow path switching valve 40 to the second position. As a result, the oil L can be drawn in from the second suction port 31 in a state where clogging of the emulsion M in the oil L inflow path is less likely to occur due to the melting of the frozen emulsion M.

[0055] (2-4) The oil temperature LT of the oil L may not be uniform within the oil pan 21. Therefore, even if the oil temperature LT of the oil L in the oil pan 21 rises to the third predetermined value PV3, the frozen emulsion M at the bottom of the oil pan 21 may not have thawed. The control device 50 does not execute the second switching process if the moisture content MC of the oil L is 4th predetermined value PV4 or higher, even if the oil temperature LT is 3 or higher. As a result, the second switching process can be executed when the frozen emulsion M has thawed.

[0056] <Example of changes> Each embodiment can be implemented with the following modifications. Each embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0057] The fuel for the internal combustion engine 10 may be hydrogen, ethanol, synthetic fuels, or other CN fuels. Furthermore, the fuel for the internal combustion engine 10 is not limited to CN fuels. The flow path switching valve 40 is not limited to a solenoid valve. The valve body of the flow path switching valve 40 may be rotated by an electric motor to switch the valve position.

[0058] If the oil pump 22 is a pump driven by an electric motor, the start of operation of the oil pump 22 is, for example, when a drive signal is output to the control circuit of the electric motor. The start of operation of the oil pump 22 is, for example, when the vehicle's main switch is turned ON.

[0059] The control device 50 may perform the first switching process when the operation of the oil pump 22 is stopped. The period when the operation of the oil pump 22 is stopped is from the time the vehicle's main switch is turned off until it is turned on again. If the oil pump 22 is a pump driven by an electric motor, the period when the operation of the oil pump 22 is stopped is from the time the output of the drive signal to the control circuit of the electric motor is stopped.

[0060] The control device 50 may perform a second switching process when the operation of the oil pump 22 is stopped, or when the operation of the oil pump 22 is stopped. The control device 50 may, in the first determination process, make a positive determination when the elapsed period ED is equal to or greater than a predetermined period PD, regardless of the rate of change CR per unit time of the discharge pressure DP.

[0061] The control device 50 may, in the second determination process, make a positive determination when the oil temperature LT is equal to or greater than the third predetermined value PV3, regardless of the moisture content MC of the oil L in the oil pan 21. In the second embodiment, the second determination process may be omitted, and the second switching process may be performed under the same conditions as in the first embodiment.

[0062] In each embodiment, the case where frozen emulsion M clogs the oil L inflow path is assumed, but the above configuration can also be applied when emulsion M, which is not frozen but has become extremely viscous at low temperatures, clogs the oil L inflow path. Furthermore, the above configuration can also be applied when ice formed by the freezing of water mixed in with oil L clogs the oil L inflow path. The freezing of water and the melting of ice can be determined in the same way as in the case of emulsion M. Therefore, the first switching process can be executed based on the occurrence of ice clogging, and the second switching process can be executed based on the elimination of the ice clogging. [Explanation of symbols]

[0063] 10...Internal combustion engine, 12...Supply part, 21...Oil pan, 22...Oil pump, 23...Strainer, 21H...Highest part, 21L...Lowest part, 24...First case, 25...Second case, 26...Intake pipe, 27...First pipe, 28...Second pipe, 29...First intake port, 31...Second intake port, 40...Flow path switching valve, 50...Control device, 51...Oil temperature acquisition unit, 52...Discharge pressure acquisition unit, 53...Elapsed time acquisition unit, 54...Moisture content acquisition unit, L...Oil, M...Emulsified, LT...Oil temperature, DP...Discharge pressure, ED...Elapsed time, MC...Moisture content, CR...Rate of change, L1...First distance, L2...Second distance, L3...Third distance, PV1...First predetermined value, PV2...Second predetermined value, PV3...Third predetermined value, PV4...Fourth predetermined value, PD...Predetermined period.

Claims

1. An internal combustion engine for vehicles, comprising an oil pan, an oil pump, and a strainer for supplying oil from the oil pan to the oil pump, A flow path switching valve that operates when power is applied, The system further comprises a control device for controlling the aforementioned flow path switching valve, The strainer includes a first pipe having a first suction port located in the oil pan and connected to the oil pump, and a second pipe having a second suction port located in the oil pan and connected to the oil pump. The distance between the first intake port and the lowest part of the oil pan in the vertical direction is greater than the distance between the second intake port and the lowest part in the vertical direction. The valve position of the flow path switching valve is switchable between a first position that connects the first suction port and the oil pump and blocks communication between the second suction port and the oil pump, and a second position that blocks communication between the first suction port and the oil pump and connects the second suction port and the oil pump. The control device is A first switching process controls the flow path switching valve so that the valve position switches from the second position to the first position when either the operation of the oil pump is started or the operation of the oil pump is stopped, After the internal combustion engine has finished warming up, a second switching process is performed to control the flow path switching valve so that the valve position switches from the first position to the second position. Internal combustion engine.

2. An internal combustion engine for vehicles, comprising an oil pan, an oil pump, and a strainer for supplying oil from the oil pan to the oil pump, A flow path switching valve that operates when power is applied, The system further comprises a control device for controlling the aforementioned flow path switching valve, The strainer includes a first pipe having a first suction port located in the oil pan and connected to the oil pump, and a second pipe having a second suction port located in the oil pan and connected to the oil pump. The distance between the first intake port and the lowest part of the oil pan in the vertical direction is greater than the distance between the second intake port and the lowest part in the vertical direction. The valve position of the flow path switching valve is switchable between a first position that connects the first suction port and the oil pump and blocks communication between the second suction port and the oil pump, and a second position that blocks communication between the first suction port and the oil pump and connects the second suction port and the oil pump. The control device is A first determination process that determines whether the elapsed time from the start of operation of the oil pump until the discharge pressure of the oil pump rises to a first predetermined value is greater than or equal to a predetermined period, when the valve position is in the second position, When the first determination process determines that the result is positive, a first switching process is performed to control the flow path switching valve so that the valve position switches from the second position to the first position. Internal combustion engine.

3. The control device further determines whether the rate of change of the discharge pressure per unit time is equal to or greater than a second predetermined value, and if the elapsed period is equal to or greater than the predetermined period and the rate of change is equal to or greater than the second predetermined value, it makes an affirmative determination in the first determination process. The internal combustion engine according to claim 2.

4. The control device is A second determination process that determines whether the oil temperature of the oil in the oil pan is equal to or greater than a third predetermined value when the valve position is in the first position, When the second determination process determines that the result is positive, a second switching process is performed to control the flow path switching valve so that the valve position switches from the first position to the second position. An internal combustion engine according to claim 2 or claim 3.

5. The control device further determines whether the moisture content of the oil at the bottom of the oil pan is less than a fourth predetermined value, and makes an affirmative determination in the second determination process when the oil temperature is equal to or greater than the third predetermined value and the moisture content is less than the fourth predetermined value. The internal combustion engine according to claim 4.

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