Control device of internal combustion engine

Abstract

To suppress oil with emulsion generated in it from sealing a cavity of a piston.SOLUTION: An internal combustion engine 10 includes: a first oil jet 56 which jets oil toward an inflow hole 25 for feeding oil to a cavity 24; and a second oil jet 58 which jets oil toward a rear surface 23 so that oil does not flow into the cavity 24. A control device 100 of the internal combustion engine 10 determines whether or not the temperature of a piston 22 is equal to or higher than a predetermined temperature as a threshold value for determining whether or not the piston 22 is superheated to a degree of requiring cooling. The control device 100 cools the piston 22 using the first oil jet 56 when the temperature of the piston 22 is the predetermined temperature or higher. The control device 100 restricts jetting of oil from the first oil jet 56 and warms up the oil using the second oil jet when the temperature of the piston 22 is lower than the predetermined temperature.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a control device for an internal combustion engine. [Background technology]

[0002] Patent Document 1 discloses a control device for an internal combustion engine that includes a first oil jet and a second oil jet. The first oil jet injects oil toward a hole that is connected to the cavity and opens on the back surface of the piston in order to flow oil into the cavity that extends inside the piston. The second oil jet injects oil into a portion of the back surface of the piston that is different from the hole. The above control device is able to maintain an appropriate temperature of the piston by using the first oil jet and the second oil jet in combination. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-218912 A Summary of the Invention [Problem to be solved by the invention]

[0004] For example, if the oil contains a large amount of water, the oil is likely to emulsify and produce an emulsion. In such a case, the emulsion may clog the cavity, making it impossible to achieve cooling using the first oil jet. [Means for solving the problem]

[0005] The means for solving the above problems and their effects will be described below. According to one aspect of the present disclosure, there is provided a control device for an internal combustion engine comprising: a first oil jet configured to inject oil toward a hole that is connected to a cavity extending inside a piston and opens to a back surface of the piston in order to flow oil into the cavity; and a second oil jet configured to inject the oil toward a portion of the back surface of the piston other than the hole, the control device comprising a processing circuit, the processing circuit being configured to acquire a temperature of the piston, determine whether the acquired temperature of the piston is equal to or higher than a specified temperature, and if the acquired temperature of the piston is equal to or higher than the specified temperature, execute a first process of injecting the oil from the first oil jet, and if the acquired temperature of the piston is less than the specified temperature, execute a second process of limiting the injection of the oil from the first oil jet and injecting the oil from the second oil jet. Effect of the Invention

[0006] It is possible to prevent the oil from emulsifying and blocking the cavities while the piston temperature is below a specified temperature and at the same time allow the oil to warm up. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram showing the relationship between an internal combustion engine control device and the internal combustion engine. [Diagram 2] FIG. 2 is a flowchart showing the process executed by the control device of FIG. [Diagram 3] FIG. 3 is a flowchart illustrating the first process shown in FIG. [Figure 4] FIG. 4 is a flowchart illustrating the second process shown in FIG. [Diagram 5] FIG. 5 is a timing chart for explaining the operation. [Figure 6] FIG. 6 is a flowchart illustrating a second process according to the modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of a control device for an internal combustion engine will be described with reference to the drawings. <Outline of the control device 100 for the internal combustion engine 10 and the internal combustion engine 10> The internal combustion engine 10 shown in Fig. 1 has a plurality of cylinders 21. Only one of the plurality of cylinders 21 is shown in Fig. 1. A piston 22 reciprocates in each cylinder 21. Each piston 22 is connected to a crankshaft via a connecting rod. The area above the piston 22 in each cylinder 21 forms a combustion chamber 28.

[0009] A cavity 24 extends inside the piston 22. The cavity 24 is a so-called cooling channel. The cavity 24 is a torus-shaped oil flow path for cooling the piston 22. An inlet hole 25 is continuous with the cavity 24 and opens to the back surface 23 of the piston 22. An outlet hole 26 is continuous with the cavity 24 and opens to the back surface 23 of the piston 22. Oil injected from a first oil jet 56, which will be described later, flows into the cavity 24 through the inlet hole 25. The oil that has flowed through the cavity 24 flows out of the piston 22 through the outlet hole 26.

[0010] In each combustion chamber 28, an air-fuel mixture containing intake air introduced via an intake passage 30 and fuel injected from a fuel injection valve 29 is combusted. The fuel is, for example, hydrogen, gasoline, or diesel. Exhaust gas generated in each combustion chamber 28 by the combustion of the air-fuel mixture is discharged to an exhaust passage 40.

[0011] The internal combustion engine 10 is also provided with an oil supply device 50 that operates to circulate oil within the internal combustion engine 10. The oil supply device 50 includes an oil pump 52 that draws up oil from within an oil pan 51. The oil supply device 50 includes a first oil jet 56 that injects oil toward the inlet hole 25 to cause the oil to flow into the cavity 24. The oil supply device 50 includes a second oil jet 58 that injects oil toward a portion of the back surface 23 of the piston 22 that is different from the inlet hole 25 and the outlet hole 26 so that the oil does not flow into the cavity 24.

[0012] The oil supply device 50 supplies oil pumped up by an oil pump 52 to each part of the internal combustion engine 10 through an oil supply passage 53. A first solenoid valve 55 is provided in the oil supply passage 53, which stops the injection of oil from a first oil jet 56 by cutting off the supply of oil to the first oil jet 56. A second solenoid valve 57 is provided in the oil supply passage 53, which stops the injection of oil from a second oil jet 58 by cutting off the supply of oil to the second oil jet 58. A cutoff mechanism 54 is provided in the oil supply passage 53, which is located upstream of the first solenoid valve 55 and the second solenoid valve 57. The cutoff mechanism 54 is capable of cutting off the supply of oil to the first oil jet 56 and the second oil jet 58.

[0013] The control device 100 includes a CPU, a RAM, and a ROM. The control device 100 operates the first solenoid valve 55 to stop the injection of oil from the first oil jet 56, or to cause the first oil jet 56 to inject oil. The control device 100 operates the second solenoid valve 57 to stop the injection of oil from the second oil jet 58, or to cause the second oil jet 58 to inject oil.

[0014] When the cut-off mechanism 54 cuts off the supply of oil to the first oil jet 56 and the second oil jet 58, even if the oil pump 52 is operating, oil is not supplied to the first oil jet 56 and the second oil jet 58. As a result, regardless of the states of the first solenoid valve 55 and the second solenoid valve 57, oil is not injected from either the first oil jet 56 or the second oil jet 58.

[0015] The control device 100 controls each part of the internal combustion engine 10 and receives signals from various sensors described below. The crank angle sensor 60 detects the rotation angle of the crankshaft. The control device 100 detects the engine rotation speed, which is the rotation speed of the crankshaft, based on the rotation angle detected by the crank angle sensor 60. The air flow meter 61 detects the intake air amount, which is the amount of air taken into the combustion chamber 28 of the internal combustion engine 10. The oil temperature sensor 62 detects the temperature of the oil in the internal combustion engine 10. The oil temperature sensor 62 may be provided, for example, in the oil pan 51 or in the oil supply passage 53. The oil moisture sensor 63 detects the moisture percentage in the oil in the internal combustion engine 10. The water temperature sensor 64 detects the temperature of the engine cooling water that cools the internal combustion engine 10. The control device 100 executes various controls described in Figs. 2 to 4 based on the output signals of the various sensors.

[0016] <Processing Executed by the Control Device 100> The process executed by the control device 100 will be described with reference to Fig. 2 to Fig. 4. The control device 100 starts the process shown in Fig. 2 when the ignition switch is switched from OFF to ON. While the ignition switch is ON, the control device 100 repeatedly executes the process shown in Fig. 2.

[0017] In step S200, the control device 100 acquires the temperature of the piston 22. In detail, the control device 100 acquires the temperature of the piston 22 by using a temperature map. The temperature map is a map that represents the relationship between the engine speed and the engine load factor, and the temperature of the piston 22. The engine load factor is a value that indicates the ratio of the current intake air amount to the maximum value of the intake air amount corresponding to the engine speed. Therefore, when the intake air amount is equal to the maximum value, the engine load factor is "100%."

[0018] In step S201, the control device 100 obtains the oil temperature from the oil temperature sensor 62. In step S202, the control device 100 obtains the moisture percentage in the oil from the oil moisture sensor 63.

[0019] In step S203, the control device 100 judges whether the acquired temperature of the piston 22 is equal to or higher than a specified temperature. The specified temperature is a threshold value for judging whether the piston 22 is overheated to the extent that cooling is required. In the case where the acquired temperature of the piston 22 is equal to or higher than the specified temperature (S203: YES), the control device 100 advances the process to step S204. In step S204, the control device 100 executes a first process of injecting oil from the first oil jet 56 to flow the oil into the cavity 24 to cool the piston 22. The first process will be described later with reference to FIG. 3. In the case where the acquired temperature of the piston 22 is lower than the specified temperature (S203: NO), the control device 100 advances the process to step S205. In step S205, the control device 100 executes a second process. In the second process, the oil injection from the first oil jet 56 is limited, and the oil is injected from the second oil jet 58 to exchange heat between the oil and the piston 22, thereby warming up the oil. The second process will be described later with reference to Fig. 4. After completing the process of step S204 or step S205, the control device 100 ends the flow of Fig. 2.

[0020] The first process will be described with reference to FIG. 3. In step S300, the control device 100 injects oil from the first oil jet 56. The oil injection is performed for several seconds, for example. Next, in step S301, the control device 100 acquires the temperature of the piston 22. Next, in step S302, the control device 100 determines whether the temperature of the piston 22 is equal to or lower than a specified temperature. This is performed to determine whether the temperature of the piston 22 has sufficiently decreased due to the injection of oil from the first oil jet 56 executed in step S300. If the temperature of the piston 22 is equal to or lower than the specified temperature (S302: YES), the control device 100 ends the flow of FIG. 3. If the temperature of the piston 22 is higher than the specified temperature (S302: NO), the control device 100 proceeds to the process in step S303. In step S303, the control device 100 injects oil from the first oil jet 56 and the second oil jet 58. When the control device 100 finishes the process of step S303, the control device 100 ends the flow of FIG.

[0021] The second process will be described with reference to FIG. 4. In step S400, the control device 100 judges whether the temperature of the piston 22 is equal to or higher than the temperature of the oil. In the case where the control device 100 judges negative in step S400 (S400: NO), the control device 100 ends the flow of FIG. 4. In the case where the control device 100 judges positive in step S400 (S400: YES), the control device 100 advances the process to step S401. In step S401, the control device 100 judges whether the moisture percentage in the oil is equal to or higher than the moisture percentage threshold. The moisture percentage threshold is, for example, 10%. The moisture percentage threshold is preset as a threshold for judging whether it is desirable to remove moisture from the oil. In the case where the control device 100 judges negative in step S401 (S401: NO), the control device 100 ends the flow of FIG. In the case where the control device 100 judges positive in step S401 (S401: YES), the control device 100 advances the process to step S402. In step S402, the control device 100 injects oil from the second oil jet 58. The oil is injected for several seconds, for example. According to steps S400 to S402, the oil is injected from the second oil jet 58 in the second process when a logical product condition consisting of the following conditions (A) and (B) is satisfied. Condition (A) is a condition that the temperature of the piston 22 is equal to or higher than the temperature of the oil. Condition (B) is a condition that the moisture content in the oil is equal to or higher than the moisture content threshold value. After completing the process of step S402, the control device 100 ends the flow of FIG. 4.

[0022] <Action of this embodiment> The operation of this embodiment will be described with reference to FIG. 5. At time T0, the ignition switch is switched from OFF to ON. Therefore, the temperature of the piston 22 starts to rise from time T0. The control device 100 also starts the process shown in FIG. 2 from time T0. Immediately after time T0, the temperature of the piston 22 is below the specified temperature (S203: NO), so the control device 100 executes step S205 and the second process shown in FIG. 4. Between time T0 and time T1, the temperature of the piston 22 is equal to or higher than the temperature of the oil (S400: YES), and the moisture content in the oil is equal to or higher than the moisture content threshold value (S401: YES). Therefore, the second oil jet 58 injects oil between time T0 and time T1.

[0023] At time T1, the moisture percentage in the oil is equal to the moisture percentage threshold value. After time T1, the moisture percentage in the oil is less than the moisture percentage threshold value. Furthermore, from time T1 to time T2, the temperature of the piston 22 is less than the specified temperature. For this reason, from time T1 to time T2, the control device 100 makes a negative determination in step S203 and also makes a negative determination in step S401. Therefore, from time T1 to time T2, oil is not injected from the second oil jet 58.

[0024] At time T2, the temperature of the piston 22 reaches the specified temperature. Immediately after time T2, the temperature of the piston 22 is equal to or higher than the specified temperature (S203: YES), so the control device 100 executes step S204 and the first process shown in FIG. 3. At time T3, the control device 100 determines that the temperature of the piston 22 is higher than the specified temperature (S302: NO). Therefore, immediately after time T3, oil is injected from the first oil jet 56 and the second oil jet 58 (S303).

[0025] At time T4, the temperature of piston 22 reaches the specified temperature. Immediately after time T4, the temperature of piston 22 is below the specified temperature. Immediately after time T4, the moisture content in the oil is below the moisture content threshold value. For this reason, control device 100 makes a negative determination in step S203 and also makes a negative determination in step S401. This means that oil is not injected from second oil jet 58.

[0026] <Effects of this embodiment> (1) The above-mentioned internal combustion engine 10 is equipped with a first oil jet 56 that is configured to inject oil toward an inlet hole 25 that is connected to the cavity 24 and opens to the back surface 23 of the piston 22 in order to flow oil into the cavity 24 extending inside the piston 22, and a second oil jet 58 that is configured to inject oil toward a portion of the back surface 23 of the piston 22 other than the inlet hole 25 and the outlet hole 26 so as to prevent oil from flowing into the cavity 24 (Figure 1). The control device 100 of the internal combustion engine 10 acquires the temperature of the piston 22 (S200), and determines whether the acquired temperature of the piston 22 is equal to or higher than a specified temperature, which is a threshold for determining whether the piston 22 has overheated to the extent that it requires cooling (S203). If the acquired temperature of the piston 22 is equal to or higher than the specified temperature, a first process is executed in which oil is injected from the first oil jet 56 to flow into the cavity 24 to cool the piston 22 (S203: YES, S204, Figure 3). If the acquired temperature of the piston 22 is less than the specified temperature, a second process is executed in which the injection of oil from the first oil jet 56 is restricted and oil is injected from the second oil jet 58 to exchange heat between the oil and the piston 22 and warm up the oil (S203: NO, S205, Figure 4).

[0027] When the temperature of the piston 22 is below a specified temperature, there is a high possibility that an emulsion of the oil will occur due to the large amount of water in the oil. In such a case, when the oil is injected using the first oil jet 56, the cavity 24 may be blocked by the oil that has caused the emulsion. Therefore, it is desirable to remove the water in the oil by warming the oil. According to the above embodiment, when the temperature of the piston 22 is below a specified temperature, the injection of the oil using the first oil jet 56 is limited. Specifically, when the temperature of the piston 22 is below a specified temperature, the injection of the oil using the first oil jet 56 is not performed. In addition, the second oil jet 58 injects the oil onto the back surface 23 of the piston 22. Therefore, while the temperature of the piston 22 is below a specified temperature, it is possible to suppress the blocking of the cavity 24 and warm up the oil at the same time.

[0028] According to the above-described control device 100, it is possible to remove moisture from the oil while the temperature of the piston 22 is below a specified temperature. Therefore, when the temperature of the piston 22 reaches or exceeds the specified temperature, cooling can be performed quickly using the first oil jet 56.

[0029] (2) The control device 100 is configured to acquire the temperature of the oil (S201). In the second process, the oil is injected from the second oil jet 58 when the temperature of the piston 22 is equal to or higher than the temperature of the oil (S400: YES, S402).

[0030] According to the above embodiment, when the temperature of the piston 22 is lower than the temperature of the oil, oil is not injected from the second oil jet 58 in the second process. For this reason, if the oil cannot be warmed up even if it is injected from the second oil jet 58, oil is not injected from the second oil jet 58. Therefore, it is possible to prevent the second oil jet 58 from wasting oil.

[0031] (3) The control device 100 is configured to acquire the moisture percentage in the oil (S202). In the second process, the oil is jetted from the second oil jet 58 when the moisture percentage in the oil is equal to or higher than the moisture percentage threshold value (S401: YES, S402).

[0032] According to the above embodiment, when the moisture content in the oil is less than the moisture content threshold value, the oil is not injected from the second oil jet 58 in the second process. Therefore, when the moisture content in the oil is so low that there is no need to remove moisture from the oil, the oil is not warmed up. Therefore, it is possible to prevent the second oil jet 58 from wasting oil.

[0033] (4) In the second process shown in FIG. 4, oil is not injected from the first oil jet 56. In this way, the control device 100 is configured to maintain the state in which oil spray from the first oil jet 56 is stopped during the second processing when the acquired temperature of the piston 22 is below the specified temperature (S203: NO, S205, Figure 4).

[0034] According to the embodiment described above, during the second process, oil is not injected from the first oil jet 56. This can minimize the possibility that the cavity 24 will be blocked by emulsion-generated oil.

[0035] <Example of change> This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction.

[0036] In the above embodiment, the inlet hole 25 and the outlet hole 26 are provided in communication with the cavity 24. For example, the outlet hole 26 may be omitted. In such a case, the oil that flows into the cavity 24 through the inlet hole 25 flows out of the cavity 24 through the inlet hole 25.

[0037] In the above embodiment, the control device 100 obtains the temperature of the piston 22 by using a temperature map. However, this is merely an example. For example, the control device 100 may use the temperature of the engine coolant detected by the water temperature sensor 64 as the temperature of the piston 22. Alternatively, for example, the control device 100 may use the temperature of the oil as the temperature of the piston 22.

[0038] Steps S301, S302, and S303 may be omitted. In the above embodiment, oil is injected from the second oil jet 58 in the second process when the logical product condition consisting of the above-mentioned condition (A) and condition (B) is satisfied. However, this is merely an example, and one or both of condition (A) and condition (B) may be omitted. That is, one or both of step S400 and step S401 may be omitted. Correspondingly, one or both of step S201 and step S202 may be omitted.

[0039] The process of step S401a shown in Fig. 6 may be executed instead of the process of step S401 in Fig. 4. In step S401a, the control device 100 sets the amount of oil to be injected from the second oil jet 58. This is performed using a map that indicates the relationship between the moisture percentage in the oil and the amount of oil to be injected from the second oil jet 58. The lower the moisture percentage in the oil, the lower the amount of oil to be injected from the second oil jet 58 is set.

[0040] According to the modified example of Figure 6, the control device 100 is configured to acquire the moisture percentage in the oil (S202), and the amount of oil injected from the second oil jet 58 in the second process is limited when the moisture percentage in the oil is low compared to when it is high (S401a).

[0041] When the moisture content of the oil is low, there is little need to warm up the oil by injecting oil from the second oil jet 58. According to the above configuration, the amount of oil injected from the second oil jet 58 in the second process is more limited when the moisture content of the oil is low than when it is high. This makes it possible to prevent oil from being wasted from the second oil jet 58 even when there is little need to warm up the oil.

[0042] The control device 100 may limit the number of cylinders 21 into which oil is injected from the second oil jet 58 in the second process when the moisture percentage in the oil is low, more than when it is high. In the above embodiment, as shown in FIG. 4, in the second process, oil is not injected from the first oil jet 56. However, this is merely an example. For example, in the second process, it is also possible to simply limit the injection of oil from the first oil jet 56. In other words, the amount of oil injected from the first oil jet 56 does not necessarily have to be set to zero.

[0043] In the above embodiment, the control device 100 includes a CPU, a RAM, and a ROM. The control device 100 executes software processing. However, this is merely an example. For example, the control device 100 may include a dedicated hardware circuit (e.g., ASIC, etc.) that processes at least a part of the software processing executed in the above embodiment. That is, the control device 100 may have any of the following configurations (a) to (c). (a) The control device 100 includes a processing device that executes all processing according to a program, and a program storage device such as a ROM that stores the program. That is, the control device 100 includes a software execution device. (b) The control device 100 includes a processing device that executes a part of the processing according to a program, and a program storage device. Furthermore, the control device 100 includes a dedicated hardware circuit that executes the remaining processing. (c) The control device 100 includes a dedicated hardware circuit that executes all processing. Here, the software execution device and / or the dedicated hardware circuit may be multiple. That is, the above processing may be executed by a processing circuitry that includes at least one of a software execution device and a dedicated hardware circuit. The software execution device and the dedicated hardware circuit included in the processing circuit may be multiple. Program storage devices or computer-readable media include storage devices that are any available media that can be accessed by a general purpose or special purpose computer. [Explanation of symbols]

[0044] 10... internal combustion engine, 22... piston, 23... back surface, 24... cavity, 25... inlet hole, 56... first oil jet, 58... second oil jet, 100... control device

Claims

1. A first oil jet configured to inject oil toward a hole that is connected to a cavity extending inside the piston and opens to a back surface of the piston in order to cause the oil to flow into the cavity; A control device for an internal combustion engine comprising: a second oil jet configured to inject the oil to a portion of the back surface of the piston other than the hole, A processing circuit is provided, the processing circuit comprising: Obtaining a temperature of the piston; determining whether the acquired temperature of the piston is equal to or higher than a specified temperature; When the acquired temperature of the piston is equal to or higher than the specified temperature, a first process is executed to inject the oil from the first oil jet; When the acquired temperature of the piston is lower than the specified temperature, a second process is executed to limit the injection of the oil from the first oil jet and to inject the oil from the second oil jet. A control device for an internal combustion engine.

2. the processing circuit is configured to obtain a temperature of the oil; Injecting the oil from the second oil jet in the second process is executed when the temperature of the piston is equal to or higher than the temperature of the oil. The control device for an internal combustion engine according to claim 1.

3. The processing circuit is configured to obtain a moisture percentage in the oil; Injecting the oil from the second oil jet in the second process is executed when the moisture content in the oil is equal to or greater than a moisture content threshold value. The control device for an internal combustion engine according to claim 1.

4. The processing circuit is configured to obtain a moisture percentage in the oil; The amount of the oil injected from the second oil jet in the second process is limited when the moisture content in the oil is low compared to when the moisture content is high. The control device for an internal combustion engine according to claim 1.

5. The processing circuit is configured to maintain a state in which the injection of the oil from the first oil jet is stopped during the second process when the acquired temperature of the piston is lower than the specified temperature. The control device for an internal combustion engine according to any one of claims 1 to 4.

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