Control device for internal combustion engines

Abstract

The present invention provides a control device for an internal combustion engine that suppresses an excessive drop in the piston crown temperature caused by increased oil injection control, which uses a larger injection amount than normal oil control. [Solution] The control device controls oil control using an oil jet. The control device performs an oil increase control in step S15 if either of the following is true: moisture content WR is greater than or equal to a first threshold L1 (S13:YES) and piston temperature TP is greater than or equal to a first temperature T1 (S14:YES), or fuel ratio FR is greater than or equal to a second threshold L2 (S16:YES) and piston temperature TP is greater than or equal to a second temperature T2 (S17:YES), and a specific control is not currently being performed (S11:YES). The control device does not perform an oil increase control in step S15 if a specific control is currently being performed (S11:YES), regardless of moisture content WR and fuel ratio FR.

Description

Technical Field

[0005] , ,

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

Background Art

[0002] Patent Document 1 discloses a control device for an internal combustion engine. The internal combustion engine includes an oil jet. The oil jet injects lubricating oil onto the back surface opposite to the top surface of the piston. When the water content ratio, which is the ratio of the amount of water contained in the lubricating oil, is equal to or higher than a first threshold value and the temperature of the piston is equal to or higher than a first temperature, the control device injects lubricating oil from the oil jet.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the control device for an internal combustion engine as described in Patent Document 1, when the water content ratio is equal to or higher than a first threshold value and the temperature of the piston is equal to or higher than a first temperature, the amount of lubricating oil injected from the oil jet may be increased compared to the case where it is not. Therefore, the lubricating oil injected from the oil jet takes heat from the piston, and depending on the controlled state of the internal combustion engine, there is a risk of excessively lowering the temperature of the top surface of the piston.

Means for Solving the Problems

[0005] A control device for an internal combustion engine to solve the above problems is applied to an internal combustion engine equipped with an oil jet that injects lubricating oil onto the back surface of a piston, and is a control device for controlling oil injection by the oil jet, wherein when neither of the following is true, the moisture content, which is the percentage of water content in the lubricating oil, is above a first threshold and the piston temperature is above a first temperature, and the fuel content, which is the percentage of fuel content in the lubricating oil, is above a second threshold and the piston temperature is above a second temperature, the control device performs normal control of the oil injection, and when at least one of the following is true, the moisture content is above the first threshold and the piston temperature is above a first temperature, and the fuel content is above the second threshold and the piston temperature is above a second temperature, the control device performs increased injection control, which is greater than the normal control of the oil injection, unless a specific control is being executed that results in a state where more fuel adheres to the piston compared to when it is not being executed, and when the specific control is being executed, the increased injection control is not performed regardless of the moisture content and fuel content. [Effects of the Invention]

[0006] With the above configuration, the control device does not perform fuel enrichment control while control is being performed to facilitate fuel adhesion to the piston. Therefore, the control device can prevent the temperature of the piston crown from dropping excessively due to fuel enrichment control. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic diagram showing a vehicle equipped with an internal combustion engine and control device. [Figure 2] Figure 2 is a flowchart showing the series of oil control processes performed by the control device. [Modes for carrying out the invention]

[0008] <One Embodiment> The following describes one embodiment of a control device for an internal combustion engine with reference to the drawings. <Internal Combustion Engine> As shown in Figure 1, the vehicle 100 is equipped with an internal combustion engine 10. The internal combustion engine 10 has a plurality of cylinders 21 and a plurality of pistons 22. In Figure 1, only one of the plurality of cylinders 21 is shown. The inside of the cylinder 21 is a cylindrical space. Inside each cylinder 21, the piston 22 reciprocates. The space within the cylinder 21 that is partitioned by the top surface of the piston 22 is the combustion chamber 28.

[0009] The internal combustion engine 10 includes a first compression ring 23, a second compression ring 24, and an oil ring 25. The first compression ring 23 is fitted into a first groove recessed in the outer circumference of the piston 22. The second compression ring 24 is fitted into a second groove recessed in the outer circumference of the piston 22. The oil ring 25 is fitted into a third groove recessed in the outer circumference of the piston 22. The components are arranged in the order of first compression ring 23, second compression ring 24, and oil ring 25, starting from the side closest to the combustion chamber 28.

[0010] The internal combustion engine 10 includes a connecting rod 26 and a crankshaft 27. The connecting rod 26 is connected to the piston 22. The connecting rod 26 extends in the direction opposite to the combustion chamber 28, with the piston 22 in between. The crankshaft 27 is connected to the connecting rod 26. The connecting rod 26 and the crankshaft 27 convert the reciprocating linear motion of the piston 22 into rotational motion.

[0011] The internal combustion engine 10 is equipped with a fuel injector 29 and a spark plug 30. The fuel injector 29 injects fuel into the combustion chamber 28. The spark plug 30 ignites the fuel-air mixture introduced into the combustion chamber 28 with a spark.

[0012] The internal combustion engine 10 includes an intake passage 31 and an exhaust passage 32. The intake passage 31 is a passage through which outside air is introduced into the combustion chamber 28. The exhaust passage 32 is a passage through which exhaust gas produced by combustion in the combustion chamber 28 flows.

[0013] The internal combustion engine 10 is equipped with a catalyst 33 and a filter 34. The catalyst 33 is located in the middle of the exhaust passage 32. The catalyst 33 is a three-way catalyst. The catalyst 33 purifies hydrocarbons, carbon monoxide, and nitrogen oxides contained in the exhaust. The catalyst 33 also has oxygen storage capacity. The filter 34 collects particulate matter contained in the exhaust. The filter 34 is located in the middle of the exhaust passage 32. The filter 34 is located downstream of the catalyst 33 in the exhaust passage 32.

[0014] The internal combustion engine 10 is equipped with an oil supply device 50. The oil supply device 50 operates to circulate lubricating oil within the internal combustion engine 10. The oil supply device 50 includes an oil pan 51, an oil pump 52, an oil supply passage 53, an oil jet 54, and a valve 55.

[0015] The oil pan 51 stores lubricating oil that is circulated within the internal combustion engine 10. The oil pan 51 is connected to the crankcase (not shown in the figure) on the side opposite to the cylinder 21. The oil pump 52 draws lubricating oil from the oil pan 51.

[0016] The first end of the oil supply passage 53 is connected to the oil pump 52. The second end of the oil supply passage 53 is connected to the oil jet 54. The oil supply passage 53 supplies lubricating oil pumped up by the oil pump 52 to the oil jet 54.

[0017] The oil jet 54 injects lubricating oil onto the back surface of the piston 22. The valve 55 is located in the middle of the oil supply passage 53. By opening and closing the valve 55, the supply of lubricating oil to the oil jet 54 is controlled. Therefore, the amount of lubricating oil injected by the oil jet 54 changes as the valve 55 is opened and closed.

[0018] <Control devices and various sensors> Vehicle 100 includes a crank angle sensor 61, an air flow meter 62, a moisture content sensor 63, a fuel ratio sensor 64, a water temperature sensor 65, an accelerator sensor 66, a brake sensor 67, a vehicle speed sensor 68, and a control device 80.

[0019] The crank angle sensor 61 detects the rotation angle of the crankshaft 27. The crank angle sensor 61 inputs a signal indicating the rotation angle of the crankshaft 27 to the control device 80. The air flow meter 62 detects the intake air amount. The intake air amount is the amount of air inhaled from the intake passage 31 into the combustion chamber 28. The air flow meter 62 inputs a signal indicating the intake air amount to the control device 80.

[0020] The moisture content sensor 63 detects the moisture content ratio WR. The moisture content ratio WR indicates the ratio of the amount of moisture contained in the lubricating oil. The moisture content sensor 63 inputs a signal indicating the moisture content ratio WR to the control device 80. The fuel ratio sensor 64 detects the fuel ratio FR. The fuel ratio FR indicates the ratio of the amount of fuel contained in the lubricating oil. The fuel ratio sensor 64 inputs a signal indicating the fuel ratio FR to the control device 80.

[0021] The water temperature sensor 65 detects the temperature of the cooling water that cools the internal combustion engine 10. The water temperature sensor 65 inputs a signal indicating the temperature of the cooling water to the control device 80. The accelerator sensor 66 detects the operation amount of the accelerator pedal of the vehicle 100. The accelerator sensor 66 inputs a signal indicating the operation amount of the accelerator pedal to the control device 80.

[0022] The brake sensor 67 detects the operation amount of the brake pedal of the vehicle 100. The brake sensor 67 inputs a signal indicating the operation amount of the brake pedal to the control device 80. The vehicle speed sensor 68 detects the vehicle speed of the vehicle 100. The vehicle speed sensor 68 inputs a signal indicating the vehicle speed to the control device 80.

[0023] The control device 80 is applied to the internal combustion engine 10. In other words, the control device 80 controls the internal combustion engine 10. The control device 80 includes a CPU 81 and a memory 82. The CPU 81 performs various controls by executing various programs stored in the memory 82.

[0024] The CPU 81 calculates the engine speed, which is the rotational speed of the crankshaft 27, based on the rotation angle of the crankshaft 27 input from the crank angle sensor 61. The CPU 81 calculates the piston temperature TP, which is the temperature of the piston 22, based on the engine speed and intake air volume. More specifically, the CPU 81 calculates the piston temperature TP using a temperature map stored in memory 82. The temperature map is a map that shows the relationship between the engine speed, engine load ratio, and the piston temperature TP. The engine load ratio is a value that shows the ratio of the current intake air volume to the maximum intake air volume corresponding to the engine speed. Therefore, when the intake air volume is equal to its maximum value, the engine load ratio is 100%. Note that the piston temperature TP increases as the engine speed increases. The piston temperature TP also increases as the engine load ratio increases.

[0025] The CPU 81 performs specific control on the internal combustion engine 10 by executing each program stored in the memory 82. The specific control is a control that causes more fuel to adhere to the piston 22 during the execution of the specific control compared to when it is not being performed. In this embodiment, the specific control includes catalyst warm-up control, filter regeneration control, idle stop control, and fuel cut control.

[0026] <Catalytic converter warm-up control> The CPU 81 performs catalyst warm-up control to heat the catalyst 33 to its activation temperature. In catalyst warm-up control, the CPU 81 retards the ignition timing in the internal combustion engine 10 compared to when the engine is running without catalyst warm-up control. This increases the temperature of the exhaust gas discharged from the cylinder 21 to the exhaust passage 32. The catalyst 33 is heated as the heated exhaust gas passes through it.

[0027] Specifically, the CPU 81 sets the ignition retardation amount in catalyst warm-up control based on the coolant temperature input from the water temperature sensor 65 and the retardation map stored in memory 82. The ignition retardation amount is the amount by which the ignition timing is retarded from the time when torque is greatest. The CPU 81 also sets the injection timing for injecting fuel in accordance with the ignition timing. In this case, the CPU 81 injects the requested amount of fuel in multiple doses. The CPU 81 sets the timing of the final injection of these multiple doses to a time retarded from top dead center of compression, in accordance with the ignition timing. Therefore, the CPU 81 sets the timing of the final injection to a time close to top dead center of compression. As a result, the fuel injected in the final dose is more likely to directly adhere to the top surface of the piston 22. In other words, catalyst warm-up control is a control that results in a state where more fuel adheres to the piston 22 during control compared to when catalyst warm-up control is not performed.

[0028] The CPU 81 estimates the temperature of the catalyst 33 based on the temperature of the coolant. If the temperature of the catalyst 33 is below the temperature at which catalyst warm-up control is not required, the CPU 81 starts catalyst warm-up control. On the other hand, if catalyst warm-up control is being performed and the temperature of the catalyst 33 rises above the temperature at which catalyst warm-up control is not required, the CPU 81 terminates the catalyst warm-up control.

[0029] <Filter playback control> The CPU 81 performs filter regeneration control to burn and purify the particulate matter deposited on the filter 34. In the filter regeneration control, the CPU 81 first executes fuel injection of the fuel injection valve 29 with the spark of the ignition plug 30 stopped, and introduces the air-fuel mixture containing the fuel injected by the fuel injection valve 29 into the catalyst 33 without burning it in the cylinder 21. As a result, the fuel of the air-fuel mixture introduced into the catalyst 33 burns inside the catalyst 33. Then, the exhaust gas heated to a high temperature due to the combustion occurring inside the catalyst 33 flows out from the catalyst 33 and flows into the filter 34. As a result, the particulate matter deposited on the filter 34 is heated by the exhaust gas at a high temperature and burns. As described above, the fuel injected with the spark of the ignition plug 30 stopped is more likely to adhere to the top surface of the piston 22 than when the spark of the ignition plug 30 is not stopped. That is, the filter regeneration control is a control in which more fuel adheres to the piston 22 during the control than when the filter regeneration control is not being performed.

[0030] In performing the filter regeneration control, the CPU 81 estimates the deposition amount of the particulate matter deposited on the filter 34 based on the history of the filter regeneration control, the engine speed, the engine load factor, and the like. Then, the CPU 81 starts the filter regeneration control when the deposition amount becomes an amount equal to or greater than the amount required to perform the filter regeneration control determined in advance. When a series of processes in which the spark of the ignition plug 30 is stopped for a predetermined period of the filter regeneration control is completed, the CPU 81 restarts the spark of the ignition plug 30 to end the filter regeneration control.

[0031] <S&S control> The CPU 81 performs so-called S&S control. In the S&S control, the CPU 81 temporarily stops the internal combustion engine 10 and then restarts it. Specifically, the S&S control includes a temporary stop process of the internal combustion engine 10 and a restart process of the internal combustion engine 10.

[0032] In S&S control, the CPU 81 performs a temporary stop operation to temporarily stop the drive of the internal combustion engine 10 when predetermined automatic stop conditions are met. The automatic stop conditions are, for example, that the accelerator pedal operation amount is zero, the vehicle speed is zero, and the brake pedal operation amount is greater than zero, all of the above conditions are met.

[0033] Furthermore, in S&S control, the CPU 81 performs a restart process to restart the internal combustion engine 10 when predetermined restart conditions are met while the internal combustion engine 10 is temporarily stopped. The restart conditions are, for example, when the automatic stop conditions mentioned above are not met. The restart process is completed when the engine rotation speed reaches a rotation speed at which it can independently continue driving after the internal combustion engine 10 has started to drive.

[0034] During the restart process, the CPU 81 sets the amount of fuel injected from the fuel injector 29 to be greater than when the restart process is not in progress. Therefore, S&S control results in a state where more fuel adheres to the piston 22 when the control is completed compared to when S&S control is not being performed.

[0035] <Fuel cut control> The CPU 81 performs fuel cut control. Fuel cut control includes a fuel stop process for fuel injection from the fuel injector 29 and a fuel restart process for fuel injection from the fuel injector 29.

[0036] In fuel cut control, the CPU 81 performs a fuel stop operation in which the crankshaft 27 rotates with the fuel supply to the internal combustion engine 10 stopped when predetermined fuel stop conditions are met. The fuel stop conditions are that the vehicle 100 is decelerating with the accelerator pedal pressed to zero, and the engine rotation speed is equal to or greater than a predetermined rotation speed. When the fuel stop conditions are met and fuel injection from the fuel injector 29 is stopped, the crankshaft 27 rotates with the fuel supply to the internal combustion engine 10 stopped.

[0037] Furthermore, in fuel cut control, the CPU 81 performs a re-injection process when predetermined re-injection conditions are met while the fuel stop process is being executed. In the re-injection process, the CPU 81 restarts fuel injection from the fuel injector 29. The re-injection process is completed when the engine speed reaches a rotational speed at which the internal combustion engine 10 can independently continue driving after it has started to operate.

[0038] During the re-injection process, the CPU 81 sets the amount of fuel injected from the fuel injector 29 to be greater than when the re-injection process is not in progress. Therefore, the fuel cut control is a control that results in a state where more fuel adheres to the piston 22 when the control is completed compared to when the fuel cut control is not in place.

[0039] <Regarding oil injection control> The CPU 81 controls the oil injection by the oil jet 54. The CPU 81 performs both normal control and increased injection control for oil injection.

[0040] In normal control, the CPU 81 controls the amount of oil injected from the oil jet 54 to increase as the estimated piston temperature TP increases. Specifically, the CPU 81 controls the amount of oil injected from the oil jet 54 by controlling the hydraulic pressure of the lubricating oil pumped up by the oil pump 52 and by controlling the opening and closing of the valve 55.

[0041] In increased flow control, the CPU 81 controls the amount of lubricating oil injected from the oil jet 54 to be greater than in normal control. Specifically, the CPU 81 controls the oil pressure of the lubricating oil pumped by the oil pump 52 to its maximum value, and controls the valve 55 to be open, thereby controlling the amount injected from the oil jet 54 to its maximum value.

[0042] During engine operation, the CPU 81 repeatedly executes the oil injection program stored in memory 82 at a predetermined interval. During engine operation, the crankshaft 27 is rotating.

[0043] As shown in Figure 2, when the CPU 81 starts executing the oil injection program, it first performs the process in step S11. In step S11, the CPU 81 determines whether or not specific control is currently being performed on the internal combustion engine 10. In this embodiment, the CPU 81 determines whether or not it is performing any of the following on the internal combustion engine 10: catalyst warm-up control, filter regeneration control, S&S control, or fuel cut control. If specific control is currently being performed on the internal combustion engine 10 (S11: YES), the CPU 81 proceeds to step S12.

[0044] In step S12, the CPU 81 performs normal control of oil injection. That is, the CPU 81 does not perform increased oil injection control. After that, the CPU 81 terminates this series of processes.

[0045] On the other hand, when no specific control is being performed on the internal combustion engine 10 (S11:NO), the CPU 81 proceeds to step S13. In step S13, the CPU 81 determines whether the moisture content WR is greater than or equal to a predetermined first threshold L1. The first threshold L1 is determined in advance through testing and simulation as the moisture content WR at which the lubricant's performance can no longer meet acceptable standards. If the moisture content WR is greater than or equal to the first threshold L1 (S13: YES), the CPU 81 proceeds to step S14.

[0046] In step S14, the CPU 81 determines whether the piston temperature TP is equal to or greater than a predetermined first temperature T1. The first temperature T1 is determined in advance through tests or simulations as the temperature at which the water contained in the lubricating oil can evaporate. For example, the first temperature T1 is 100 degrees Celsius. If the piston temperature TP is equal to or greater than the first temperature T1 (S14: YES), the CPU 81 proceeds to step S15.

[0047] In step S15, the CPU 81 performs an oil increase control. That is, if the CPU 81 makes a positive determination in step S13 and also makes a positive determination in step S14, the CPU 81 performs an oil increase control. After that, the CPU 81 terminates this series of processes.

[0048] On the other hand, when the moisture content WR is less than the first threshold L1 (S13:NO), the CPU 81 proceeds to step S16. Also, when the piston temperature TP is less than the first temperature T1 (S14:NO), the CPU 81 proceeds to step S16.

[0049] In step S16, the CPU 81 determines whether the fuel ratio FR is equal to or greater than a predetermined second threshold L2. The second threshold L2 is determined in advance through tests and simulations as the fuel ratio FR at which the lubricant performance can no longer meet acceptable performance standards. If the fuel ratio FR is equal to or greater than the second threshold L2 (S16: YES), the CPU 81 proceeds to step S17.

[0050] In step S17, the CPU 81 determines whether the piston temperature TP is equal to or greater than a predetermined second temperature T2. The second temperature T2 is determined in advance through tests and simulations as the temperature at which the fuel contained in the lubricating oil can evaporate. If the piston temperature TP is equal to or greater than the second temperature T2 (S17: YES), the CPU 81 proceeds to step S15.

[0051] In step S15, as described above, the CPU 81 performs an oil increase control. That is, if the process in step S16 is positive and the process in step S17 is positive, the CPU 81 performs an oil increase control. Therefore, the CPU 81 performs an oil increase control if at least one of the following conditions is met: the process in step S13 is positive and the process in step S14 is positive, and the process in step S16 is positive and the process in step S17 is positive. After that, the CPU 81 terminates this series of processes.

[0052] On the other hand, when the fuel ratio FR is less than the second threshold L2 (S16:NO), the CPU 81 proceeds to step S18. Also, when the piston temperature TP is less than the second temperature T2 (S17:NO), the CPU 81 proceeds to step S18.

[0053] In step S18, the CPU 81 performs normal oil control. That is, the CPU 81 performs normal oil control if it does not receive a positive result in step S13 and step S14, or if it does not receive a positive result in step S16 and step S17. After that, the CPU 81 terminates this series of processes.

[0054] In this way, when specific control is being performed on the internal combustion engine 10 (S11:YES), regardless of the moisture content WR and fuel content FR, the CPU 81 performs normal control in step S12 without performing increased oil injection control.

[0055] <Operation and Effects of This Embodiment> (1) When the moisture content WR is greater than or equal to the first threshold L1 and the piston temperature TP is greater than or equal to the first temperature T1, the CPU 81 performs an increased oil control. This increases the amount of lubricating oil injected onto the back surface of the piston 22, thereby increasing the amount of lubricating oil that receives heat from the piston 22. As a result, evaporation of moisture contained in the lubricating oil can be promoted.

[0056] When the fuel ratio FR is above the second threshold L2 and the piston temperature TP is above the second temperature T2, the CPU 81 performs an increased oil control. This increases the amount of lubricating oil injected onto the back surface of the piston 22, thereby increasing the amount of lubricating oil that receives heat from the piston 22. As a result, the evaporation of fuel contained in the lubricating oil can be promoted.

[0057] On the other hand, while specific control is being performed on the internal combustion engine 10, the CPU 81 does not perform increased oil control. Therefore, in a situation where the temperature of the piston 22's crown is likely to decrease due to fuel adhering to the crown surface of the piston 22 as a result of the specific control, the control device 80 prevents an excessive amount of lubricating oil from being injected onto the back surface of the piston 22. Thus, the control device 80 can suppress an excessive decrease in the temperature of the piston 22's crown surface due to increased oil control.

[0058] (2) The specific control includes catalytic converter warm-up control. In catalytic converter warm-up control, the fuel injection timing makes it easier for more fuel to adhere to the top surface of the piston 22. Furthermore, when catalytic converter warm-up control is being performed on the internal combustion engine 10, the control device 80 does not perform the oil control enrichment control. This allows the control device 80 to prevent the temperature of the top surface of the piston 22 from dropping excessively during catalytic converter warm-up control.

[0059] (3) The specific control includes filter regeneration control. In filter regeneration control, fuel injected with the spark plug 30 stopped is more likely to adhere to the top surface of the piston 22. Furthermore, the control device 80 does not perform oil enrichment control while filter regeneration control is being performed on the internal combustion engine 10. This allows the control device 80 to prevent the temperature of the top surface of the piston 22 from dropping excessively during filter regeneration control.

[0060] (4) The specific control includes S&S control, which temporarily stops and then restarts the internal combustion engine 10. In the restart process of S&S control, the amount of fuel injected is increased, making it easier for more fuel to adhere to the top surface of the piston 22. Furthermore, the control device 80 does not perform the oil control increase control while S&S control is being performed on the internal combustion engine 10. This allows the control device 80 to prevent the temperature of the top surface of the piston 22 from dropping excessively during S&S control.

[0061] (5) When specific control is being performed on the internal combustion engine 10, the control device 80 performs normal control without performing enrichment control. By doing so, the control device 80 can prevent excessive restriction of the lubricating oil injection amount by not performing enrichment control.

[0062] <Example of changes> The above embodiment can be implemented with the following modifications. The above embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0063] The specific control does not have to include catalyst warm-up control. The specific control does not have to include filter regeneration control. The specific control does not have to include S&S control. The specific control does not have to include fuel cut control. The specific control is a control that, while in operation, results in more fuel adhering to the piston compared to when it is not in operation. For example, if vehicle 100 is a hybrid vehicle, the specific control may be intermittent control.

[0064] The types of sensors provided by the vehicle 100 are not limited to the examples of the above embodiment. For example, the vehicle 100 does not need to be equipped with a moisture content sensor 63. In this case, the control device 80 may calculate the moisture content WR based on the engine rotation speed or the like.

[0065] The control device 80 does not have to perform specific control. For example, specific control may be performed by a device other than the control device 80. The method for calculating the piston temperature TP is not limited to the examples of the above embodiment. For example, the CPU 81 may calculate the piston temperature TP based on the temperature of the coolant detected by the water temperature sensor 65. Alternatively, the CPU 81 may calculate the piston temperature TP based on the wall temperature of the cylinder 21, i.e., the bore wall temperature. Alternatively, the CPU 81 may calculate it based on the cumulative intake air volume.

[0066] The CPU 81 may perform steps S16 and S17 regardless of the result of the judgment in step S14. In this case, the CPU 81 should perform the increase control if either of the following conditions is met: the judgment in step S13 is positive and the judgment in step S14 is positive, or the judgment in step S16 is positive and the judgment in step S17 is positive. Alternatively, the CPU 81 may perform steps S16 and S17 before the processing of steps S13 and S14. In this case, the CPU 81 should perform step S13 if it makes a negative judgment in either step S16 or step S17.

[0067] The CPU 81 does not need to perform normal control in step S12. The CPU 81 does not need to perform increased quantity control in step S12. For example, in the process of step S12, the CPU 81 may set the amount of lubricating oil injected to be less than in the case of normal control.

[0068] • For enrichment control, it is sufficient that the amount of fuel injected from the oil jet 54 is greater than that for normal control. Therefore, the amount of fuel injected from the oil jet 54 in enrichment control does not have to be the maximum amount. For example, if the normal control of oil control is a control that does not inject lubricating oil, the enrichment control may be a control that injects lubricating oil.

[0069] The oil supply device 50 may be configured so that the amount of fuel injected from the oil jet 54 is controlled only by opening and closing the valve 55. In this case, the control device 80 may increase the amount of fuel injected from the oil jet 54 by making the proportion of time the valve 55 is open longer than the proportion of time the valve 55 is open in normal control.

[0070] The detailed structure of the internal combustion engine 10 is not limited to the examples of the embodiments described above. For example, the internal combustion engine 10 may include port injection valves in addition to the fuel injection valve 29. [Explanation of Symbols]

[0071] 10... Internal combustion engine 21 cylinders 22... Piston 31…Intake passage 32... Exhaust passage 33… Catalyst 34…Filter 54… Oil jet 80...Control device FR…Fuel rate L1...First threshold L2…Second threshold T1…1st temperature T2…Second temperature WR…Moisture percentage

Claims

1. A control device for controlling oil injection by an oil jet, which is applied to an internal combustion engine equipped with an oil jet that injects lubricating oil onto the back surface of a piston, When neither of the following conditions is met: the moisture content, which is the percentage of water contained in the lubricating oil, is above a first threshold and the piston temperature is above a first temperature; nor is the fuel content, which is the percentage of fuel contained in the lubricating oil, above a second threshold and the piston temperature is above a second temperature; then, normal control of the oil injection is performed. When the moisture content is equal to or greater than the first threshold and the piston temperature is equal to or greater than the first temperature, and when the fuel content is equal to or greater than the second threshold and the piston temperature is equal to or greater than the second temperature, if a specific control is not being performed which results in a state where more fuel adheres to the piston compared to when it is not being performed, then an increased injection control is performed which is greater than the normal control of the oil injection. When the aforementioned specific control is being performed, the enrichment control will not be performed regardless of the moisture content and fuel content. Control device for internal combustion engines.

2. The internal combustion engine comprises an exhaust passage through which exhaust gas produced by the combustion of fuel in the cylinder flows, and a catalyst disposed in the exhaust passage. The aforementioned specific control includes catalyst warm-up control for warming up the catalyst. A control device for an internal combustion engine according to claim 1.

3. The internal combustion engine comprises an exhaust passage through which exhaust gas produced by the combustion of fuel in the cylinder flows, and a filter positioned in the exhaust passage to collect particulate matter contained in the exhaust gas. The aforementioned specific control includes filter regeneration control for regenerating the filter. A control device for an internal combustion engine according to claim 1.

4. The aforementioned specific control includes control to temporarily stop and then restart the internal combustion engine. A control device for an internal combustion engine according to claim 1.

5. If the aforementioned specific control is being performed, the normal control will be performed without performing the increase control. A control device for an internal combustion engine according to claim 1.

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