Control device for internal combustion engine

Abstract

To suppress the direct adhesion of fuel to a piston caused by final fuel injection during catalyst warm-up processing.SOLUTION: A control device of an internal combustion engine performs catalyst warm-up processing for promoting the warm-up of a catalyst by setting an ignition timing TA of an ignition plug to a retardation side rather than a compressor top dead point. When setting a quantity of fuel supplied for one-time combustion as a requirement injection quantity, the control device determines the number of times of injection necessary for injecting the requirement injection quantity from an in-cylinder injection valve, and performs injection control processing for determining each-time injection timing of the fuel. When setting a final fuel injection timing which is determined by the injection control processing as a final injection timing, the control device sets the ignition timing TA to a retardation side rather than a regulation timing ST during catalyst warm-up in the injection control processing (S14: YES), and when a plurality of number of times is determined as the number of times of injection, the control device sets the final injection timing at timing after the regulation timing ST and before the ignition timing TA (S15).SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] The internal combustion engine described in Patent Document 1 includes a piston that reciprocates in a cylinder, an in-cylinder injection valve that injects fuel into the cylinder, an ignition plug that ignites the air-fuel mixture in the cylinder, and an exhaust passage through which exhaust gas from the cylinder flows. The control device for the internal combustion engine described in Patent Document 1 calculates a required injection amount, which is the amount of fuel used for one combustion. The control device can also determine multiple injections as the number of fuel injections when injecting the required injection amount. When multiple injections are determined as the number of injections, the in-cylinder injection valve divides the required injection amount into multiple injections. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-024682 A Summary of the Invention [Problem to be solved by the invention]

[0004] A technique is known for performing a catalyst warm-up process for warming up a catalyst provided in an exhaust passage in an internal combustion engine. In addition, as part of this catalyst warm-up process, the ignition timing is set to a timing on the retard side of the compression top dead center. When this catalyst warm-up process is applied to the internal combustion engine of Patent Document 1, it is possible that the split fuel injection process and the catalyst warm-up process are both performed. In this case, it is preferable to set the injection timing of the final injection of the multiple fuel injections to a timing on the retard side of the compression top dead center in accordance with the ignition timing. By performing the final injection in accordance with the ignition timing in this manner, combustion is stabilized.

[0005] As described above, if the injection timing of the final injection is determined according to the ignition timing during the catalyst warm-up process, the final fuel injection may occur when the ignition timing is close to the top dead center. In this case, there is a risk that the fuel injected by the cylinder injection valve will directly adhere to the piston. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention is applied to an internal combustion engine including a piston that reciprocates within a cylinder, an in-cylinder injection valve that injects fuel into the cylinder, an ignition plug that ignites the air-fuel mixture in the cylinder, an exhaust passage through which exhaust from the cylinder flows, and a catalyst provided in the exhaust passage, and includes a catalyst warm-up process that promotes warm-up of the catalyst by retarding the ignition timing of the spark plug from the compression top dead center, and an injection control process that, when the amount of fuel provided for one combustion is a required injection amount, determines the number of injections required to inject the required injection amount from the in-cylinder injection valve and determines the injection timing of each fuel injection, Run When the final fuel injection timing determined by the injection control process is defined as the final injection timing, if the ignition timing during the catalyst warm-up process becomes more retarded than a specified timing that is predetermined as a timing more retarded than the compression top dead center and the number of injections is determined to be multiple, this is a control device for an internal combustion engine that sets the final injection timing to a timing after the specified timing and before the ignition timing.

[0007] According to the above configuration, even if the ignition timing is retarded from the specified timing by the catalyst warm-up process, the final injection timing is set to a time after the specified timing and before the ignition timing. At the time on the retard side of the specified timing, the position of the piston is considerably far from the top dead center. Therefore, it is possible to prevent the fuel from the final injection from directly adhering to the piston.

[0008] In the control device for an internal combustion engine, in the injection control process, the final injection timing may be determined to be the same timing as the ignition timing. According to the above configuration, the final injection is performed at a timing after the specified time and before the ignition timing, when the piston is farthest from the top dead center, thereby more effectively preventing the fuel from the final injection from adhering directly to the piston.

[0009] In the control device for an internal combustion engine, in the injection control process, the final injection timing may be determined to be the same timing as the specified timing. With the above configuration, a sufficient amount of time can be ensured between the final injection timing and the ignition timing for the fuel injected in the final injection to reach the vicinity of the tip of the spark plug, so that when the spark plug ignites, a mixture with a fuel concentration suitable for ignition is likely to be produced near the tip of the spark plug.

[0010] In the control device for an internal combustion engine, a specifying process may be further executed to determine the specified timing to be a timing on the more advanced side as the cooling water temperature of the internal combustion engine decreases. In the above configuration, the lower the cooling water temperature, the more unstable the combustion in the cylinder becomes. According to the above embodiment, the specification process specifies the specified timing to be more advanced as the cooling water temperature decreases. In other words, the process of setting the final injection timing to a timing after the specified timing and before the ignition timing is more likely to be executed. Therefore, when the cooling water temperature is low, it is possible to prevent the fuel injected in the final injection from adhering to the piston and causing the combustion in the cylinder to become unstable. In addition, since the final injection timing is considerably close to the ignition timing, the ignition of the fuel by the spark plug does not become excessively unstable. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing an internal combustion engine. [Diagram 2] FIG. 2 is a flowchart showing a processing procedure for control at the start of an internal combustion engine. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] As shown in FIG. 1, the internal combustion engine 20 has a cylinder block 21, a cylinder head 22, a piston 23, and a cylinder 24. The cylinder 24 is a cylindrical space defined inside the cylinder block 21. Both ends of the cylinder 24 in a direction along the central axis are open to the outside of the cylinder block 21. The piston 23 is disposed inside the cylinder 24. The piston 23 reciprocates inside the cylinder 24. The top surface of the piston 23 faces a first end in a direction along the central axis of the cylinder 24. The cylinder head 22 is connected to the cylinder block 21. The cylinder head 22 has a recess 25. The recess 25 is recessed in the outer surface of the cylinder head 22. The recess 25 faces the cylinder 24 in a direction along the central axis of the cylinder 24. The wall surface of the cylinder block 21 that defines the cylinder 24, the wall surface of the recess 25, and the top surface of the piston 23 define a combustion chamber R.

[0013] The internal combustion engine 20 has a connecting rod 26 and a crankshaft 27. The connecting rod 26 is connected to the piston 23. The connecting rod 26 extends in the opposite direction to the cylinder head 22, sandwiching the piston 23 therebetween. 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 23 into rotational motion.

[0014] The internal combustion engine 20 has an intake port 28. The intake port 28 is a space defined inside the cylinder head 22. A first end of the intake port 28 opens toward the recess 25. A second end of the intake port 28 opens toward the outside of the cylinder head 22.

[0015] The internal combustion engine 20 has an exhaust port 29. The exhaust port 29 is a space defined inside the cylinder head 22. A first end of the exhaust port 29 opens toward the recess 25. A second end of the exhaust port 29 opens toward the outside of the cylinder head 22.

[0016] The internal combustion engine 20 includes an intake valve 30 and an exhaust valve 31. The intake valve 30 is a valve that opens and closes a first end of the intake port 28. The exhaust valve 31 is a valve that opens and closes a first end of the exhaust port 29.

[0017] Although FIG. 1 illustrates only one set of the combustion chamber R and the configuration related to the combustion chamber R, the internal combustion engine 20 includes a plurality of sets of these configurations. The internal combustion engine 20 has an intake passage 41 for drawing in outside air. The intake passage 41 is connected to a second end of the intake port 28. The intake passage 41 houses a throttle valve 42. The throttle valve 42 adjusts the intake air amount GA, which is the flow rate of air flowing through the intake passage 41, by changing the valve opening degree. The air drawn in through the intake passage 41 flows into the combustion chamber R via the intake port 28.

[0018] The internal combustion engine 20 is equipped with an in-cylinder injection valve 44. The in-cylinder injection valve 44 is attached to the cylinder head 22. The tip of the in-cylinder injection valve 44 is located in the combustion chamber R. The in-cylinder injection valve 44 injects fuel directly into the combustion chamber R without passing through the intake port 28.

[0019] The internal combustion engine 20 is equipped with an ignition plug 45. The ignition plug 45 is attached to the cylinder head 22. The ignition plug 45 is located between the intake port 28 and the exhaust port 29. The tip of the spark plug 45 is located near the tip of the in-cylinder injection valve 44. The spark plug 45 ignites the air-fuel mixture introduced into the combustion chamber R by a spark. That is, the spark plug 45 ignites the air-fuel mixture in the cylinder 24.

[0020] The internal combustion engine 20 includes an exhaust passage 51 through which exhaust gas generated by combustion in the combustion chamber R flows. That is, exhaust gas from the cylinder 24 flows through the exhaust passage 51. The exhaust passage 51 is also connected to a second end of the exhaust port 29.

[0021] The internal combustion engine 20 is equipped with a catalyst 52. The catalyst 52 is provided in the exhaust passage 51. The catalyst 52 is a three-way catalyst, and purifies the hydrocarbons, carbon monoxide, and nitrogen oxides contained in the exhaust gas. The catalyst 52 also has an oxygen storage capacity.

[0022] The internal combustion engine 20 is equipped with a filter 53. The filter 53 is located downstream of the catalyst 52 in the exhaust passage 51. The filter 53 collects particulate matter contained in the exhaust gas.

[0023] The vehicle having the internal combustion engine 20 mounted thereon is provided with a crank angle sensor 91. The crank angle sensor 91 is located in the vicinity of the crankshaft 27. The crank angle sensor 91 detects the rotation phase SC of the crankshaft 27.

[0024] The vehicle is equipped with an air flow meter 92. The air flow meter 92 is located upstream of the throttle valve 42 in the intake passage 41. The air flow meter 92 detects the intake air amount GA, which is the flow rate of air flowing through the intake passage 41.

[0025] The vehicle is provided with a coolant temperature sensor 93. The coolant temperature sensor 93 detects the coolant temperature TW, which is the temperature of the coolant that cools the internal combustion engine 20. The vehicle is equipped with a driving switch 94. The driving switch 94 is turned on when starting the driving of the internal combustion engine 20, and is turned off when stopping the driving of the internal combustion engine 20. R It is a switch.

[0026] A vehicle equipped with the above-mentioned internal combustion engine 20 is equipped with a control device 100. The control device 100 controls the internal combustion engine 20. The control device 100 obtains a signal indicating the rotation phase SC of the crankshaft 27 from a crank angle sensor 91. The control device 100 obtains a signal indicating the intake air amount GA from an air flow meter 92. The control device 100 obtains a signal indicating the coolant temperature TW from a coolant temperature sensor 93. The control device 100 obtains an ON signal for starting the operation of the internal combustion engine 20 and an OFF signal for stopping the operation of the internal combustion engine 20 from an operation switch 94.

[0027] The control device 100 includes a CPU 101, a peripheral circuit 102, a ROM 103, a storage device 104, and a bus 105. The bus 105 connects the CPU 101, the peripheral circuit 102, the ROM 103, and the storage device 104 so that they can communicate with one another. The peripheral circuit 102 includes a circuit that generates a clock signal that regulates internal operations, a power supply circuit, a reset circuit, and the like. The ROM 103 stores various programs in advance for the CPU 101 to execute various controls. The CPU 101 executes the various programs stored in the ROM 103 to control the internal combustion engine 20, particularly the in-cylinder injection valve 44 and the spark plug 45.

[0028] (Ignition timing control) The control device 100 executes ignition timing control with the spark plug 45 as the control target. In the ignition timing control, the CPU 101 calculates the ignition timing TA of the internal combustion engine 20 based on the engine load KL and the engine speed NE. Then, the CPU 101 controls the operation of the spark plug 45 so that the ignition operation by the spark plug 45 is performed at the ignition timing TA. Note that in this embodiment, a value obtained by dividing the intake air amount GA by the engine speed NE is used as the engine load KL. The CPU 101 calculates the engine speed NE based on the rotation phase SC acquired from the crank angle sensor 91.

[0029] In this embodiment, the CPU 101 executes normal processing and catalyst warm-up processing as ignition timing control. Note that in the following, the compression top dead center is set to "0", the ignition timing TA set before the compression top dead center is set to a positive value, and the ignition timing TA set after the compression top dead center is set to a negative value. Therefore, the value of the ignition timing TA increases as it is set to the advanced angle side.

[0030] When the catalyst warm-up process is not executed, the CPU 101 executes normal processing. In the normal processing, the CPU 101 calculates the basic ignition timing TB based on the engine load KL and the engine speed NE. Then, the CPU 101 calculates the basic ignition timing TB as the ignition timing TA.

[0031] During a cold start of the internal combustion engine 20, the CPU 101 executes a catalyst warm-up process that promotes warm-up of the catalyst 52 by retarding the ignition timing TA of the spark plug 45 from the compression top dead center. When the cooling water temperature TW at the start is equal to or lower than a specified temperature, the CPU 101 determines that the internal combustion engine 20 is in a cold start state and executes the catalyst warm-up process.

[0032] In the catalyst warm-up process, the CPU 101 first calculates the basic ignition timing TB based on the engine load KL and the engine speed NE. Next, the CPU 101 calculates the ignition timing TA by adding a predetermined retard correction amount AR to the basic ignition timing TB. The retard correction amount AR is a negative value, and the smaller the value, that is, the larger the absolute value, the more the corrected ignition timing TA is set to the retard side. Therefore, in the catalyst warm-up process, the calculated ignition timing TA is set to the retard side compared to the normal process. Furthermore, the retard correction amount AR is set so that the ignition timing TA calculated by adding it to the basic ignition timing TB is retarded from the compression top dead center. Therefore, the ignition timing TA calculated in the catalyst warm-up process is calculated as a timing retarded from the compression top dead center.

[0033] In the catalyst warm-up process, the CPU 101 operates the spark plug 45 to ignite at the ignition timing TA calculated by adding the retard correction amount AR. This causes the ignition timing TA of the spark plug 45 to be retarded from the compression top dead center, thereby accelerating the warm-up of the catalyst 52.

[0034] (Injection control process) The control device 100 executes an injection control process by controlling the in-cylinder injection valve 44. In the injection control process, the CPU 101 first calculates a required injection amount, which is the amount of fuel used for one combustion. The CPU 101 calculates the required injection amount based on the engine load KL and the engine speed NE.

[0035] Next, the CPU 101 determines the number of injections required to inject the required injection amount from the in-cylinder injection valve 44, and determines the injection timing of each injection. Multiple times Injection, or 1 time By selecting the injection, the number of injections and the injection timing are determined.

[0036] 1 time The injection frequency is one. Therefore, 1 time The injection amount in the first injection is the required injection amount. 1 time The injection timing of the first injection is a timing before the compression top dead center, for example, 160 degrees before the compression top dead center. 1 time In the case of injection, the ignition timing TA is changed depending on whether the catalyst is warming up or not.

[0037] Multiple timesThe number of injections is two, and the injection amount and injection timing of each injection are determined as follows: The injection amount for the first injection is 97% of the required injection amount. The injection timing for the first injection is 160 degrees before the compression top dead center. The injection amount for the second, i.e., the final injection is 3% of the required injection amount. The final injection timing, which is the timing for the second injection, is determined to be after the predetermined specified timing ST and before the ignition timing TA. In this embodiment, the final injection timing is the same as the ignition timing TA. The specified timing ST is determined to be a timing that is retarded from the compression top dead center, and details will be described later.

[0038] (Regarding start-up control) Hereinafter, a description will be given of the ignition timing control process and the injection control process at the start of the internal combustion engine 20 by the control device 100. When the CPU 101 receives an ON signal from the operation switch 94, it starts a series of start-up controls shown in FIG.

[0039] As shown in FIG. 2, when the CPU 101 starts the start-up control, the CPU 101 first executes the process of step S11. In step S11, the CPU 101 determines whether or not the catalyst warm-up condition is satisfied. Specifically, the CPU 101 compares the cooling water temperature TW with a predetermined specified temperature. The specified temperature is, for example, several degrees Celsius to several tens of degrees Celsius. If the cooling water temperature TW is equal to or lower than the specified temperature, the CPU 101 determines that the engine is in a cold start state, that is, the catalyst warm-up condition is satisfied. If the cooling water temperature TW exceeds the specified temperature, the CPU 101 determines that the catalyst warm-up condition is not satisfied. In this case (S11: NO), the CPU 101 proceeds to step S21, assuming that the catalyst warm-up process is not performed in the current start-up control.

[0040] In step S21, the CPU 101 calculates the ignition timing TA. In step S21, the ignition timing TA is calculated by selecting normal processing. That is, as described above, the CPU 101 calculates the basic ignition timing TB based on the engine load KL and the engine speed NE. Then, the CPU 101 calculates the basic ignition timing TB as the ignition timing TA. After that, the CPU 101 advances the process to step S22.

[0041] In step S22, the CPU 101 executes the following as the injection control process: 1 time Select injection. This causes the CPU 101 to 1 time The number of injections and the injection timing are determined. That is, in this case, the number of injections is 1, and the injection timing is 160 degrees. After that, the CPU 101 ends a series of processes in the current start-up control.

[0042] On the other hand, when the CPU 101 determines that the cooling water temperature TW is equal to or lower than the specified temperature and thus satisfies the catalyst warm-up condition (S11: YES), the CPU 101 advances the process to step S12. In step S12, the CPU 101 calculates the ignition timing TA as the injection control process. The CPU 101 calculates the ignition timing TA by selecting the catalyst warm-up process. That is, as described above, the CPU 101 calculates the ignition timing TA by adding the predetermined retard correction amount AR to the basic ignition timing TB. Then, the process proceeds to step S13.

[0043] In step S13, CPU 101 executes a specifying process to calculate specified time ST. In the specifying process, CPU 101 calculates specified time ST as a timing on the retard side of compression top dead center based on cooling water temperature TW. CPU 101 calculates specified time ST so that the lower the cooling water temperature TW, the more advanced the timing becomes. In this embodiment, regardless of cooling water temperature TW, specified time ST is calculated as a timing on the retard side of 15 degrees or more after compression top dead center. In other words, the maximum value of specified time ST is -15 degrees. CPU 101 then advances the process to step S14.

[0044] In step S14, the CPU 101 determines whether the ignition timing TA is retarded from the specified timing ST. If the ignition timing TA is retarded from the specified timing ST (S14: YES), the CPU 101 advances the process to step S15.

[0045] In step S15, the CPU 101 executes the following as the injection control process: Multiple times Select the injection. Multiple times When the injection is selected, the CPU 101 controls the in-cylinder injection valve 44 and the ignition plug 45 so that the in-cylinder injection valve 44 and the ignition plug 45 Multiple times That is, the CPU 101 determines the number of injections to be multiple on the condition that the ignition timing TA becomes more retarded than the specified timing ST during the catalyst warm-up.

[0046] Specifically, CPU 101 sets the number of injections to two. For the first injection, CPU 101 sets the injection timing to 160 degrees before top dead center of compression and the injection amount to 97% of the required injection amount. For the second, i.e., final injection, CPU 101 sets the injection timing to a timing after specified timing ST and before ignition timing TA and the injection amount to 3% of the required injection amount. In particular, CPU 101 operates in-cylinder injection valve 44 so that the final injection timing, which is the timing of the final injection, is the same timing as ignition timing TA. CPU 101 operates in-cylinder injection valve 44 so that the fuel from the final injection induces discharge near the tip of ignition plug 45.

[0047] On the other hand, if the ignition timing TA is not on the retarded side of the specified timing ST (S14: NO), the CPU 101 advances the process to step S16. In step S16, the CPU 101 executes the following as the injection control process: 1 time Then, the CPU 101 controls the in-cylinder injection valve 44 and the ignition plug 45 so that the in-cylinder injection valve 44 and the ignition plug 45 1 time Perform injection.

[0048] Specifically, the CPU 101 sets the number of injections to one. The CPU 101 sets the injection timing to 160 degrees before top dead center of compression and the injection amount to a required injection amount, and operates the in-cylinder injection valve 44. The CPU 101 then operates the spark plug 45 to ignite at the ignition timing TA. The ignition timing TA at this time is the ignition timing TA determined in step S12, that is, the timing obtained by adding the retard correction amount AR to the basic ignition timing TB. Thus, in the start-up control of this embodiment, the calculation of the ignition timing TA in step S12 and the operation of the spark plug 45 in step S15 or step S16 constitute the catalyst warm-up process.

[0049] After completing the process of step S15 or after completing the process of step S16, the CPU 101 advances the process to step S17. In step S17, the CPU 101 determines whether or not a catalyst warm-up end condition is satisfied. The catalyst warm-up end condition is a condition indicating whether or not the temperature of the catalyst 52 has become sufficiently high. The catalyst warm-up end condition is, for example, when the temperature of the catalyst 52 has reached a specified temperature or higher, or when the process of S15 has been repeated a specified number of times, Multiple times The injection process was carried out.

[0050] If the catalyst warm-up end condition is not satisfied (S17: NO), CPU 101 returns the process to step S12. On the other hand, if the catalyst warm-up end condition is satisfied (S17: YES), CPU 101 ends the current series of processes for the start-up control. In other words, "catalyst warm-up in progress" refers to the state from when an affirmative determination is made in step S11 to when an affirmative determination is made in step S17 in the series of start-up controls shown in FIG.

[0051] (Operation of the embodiment) Multiple times According to the injection, the spark plug 45 ignites a small amount of fuel from the final injection while it is located near the spark plug 45. Therefore, the fuel from the final injection becomes the spark and the combustion propagates to the combustion chamber R. In other words, Multiple times The injection stabilizes the combustion in the combustion chamber R.

[0052] On the other hand, the time until the fuel from the final injection is ignited is quite short. Furthermore, the position of the piston 23 at the time of the final injection is close to the compression top dead center. Therefore, the injected fuel may directly adhere to the piston 23. If combustion begins with the piston 23 wet with fuel, particulate matter such as soot will increase.

[0053] (Effects of the embodiment) (1) According to the above embodiment, when the ignition timing TA becomes later than the specified timing ST due to the catalyst warm-up process, the control device 100 Multiple times Therefore, when the ignition timing TA is on the retard side of the specified timing ST, the number of injections is determined to be multiple. Multiple times The final injection timing is set to a timing after the specified timing ST and before the ignition timing TA.

[0054] If the position of the piston 23 is closer to the top dead center than the position at the specified time ST, the distance between the top surface of the piston 23 and the direct injection valve 44 is short. Therefore, the fuel injected from the direct injection valve 44 is likely to adhere to the top surface of the piston 23. According to the above embodiment, Multiple times The timing of the final injection is later than the specified time ST. Therefore, the position of the piston 23 is considerably distant from the in-cylinder injection valve 44. Therefore, according to the above embodiment, Multiple times This makes it possible to prevent the fuel from the final injection from directly adhering to the piston 23.

[0055] (2) According to the above embodiment, the CPU 101 determines the final injection timing to be the same as the ignition timing TA. Multiple times The final injection is performed at the timing after the specified timing ST and before the ignition timing TA when the piston 23 is furthest from the top dead center. This makes it possible to more effectively prevent the fuel from the final injection from directly adhering to the piston 23.

[0056] (3) In the internal combustion engine 20, the lower the cooling water temperature TW, the less likely the fuel is to atomize and evaporate, and this causes the combustion in the combustion chamber R to become unstable. In the above embodiment, the specification process specifies the specified timing ST to be more advanced as the cooling water temperature TW decreases. In other words, the lower the cooling water temperature TW, the more likely it is that the above-mentioned step S15 will be advanced. Multiple times This makes it easier to execute the injection. Multiple times When injection is performed, the number of injections is determined to be two, and the final injection timing is determined to be the same as the ignition timing TA. By matching the final injection timing with the ignition timing TA in this way, the fuel can be burned stably even when the cooling water temperature TW is low.

[0057] (4) According to the above embodiment, the specified time ST is a time that is 15 degrees or more retarded after the compression top dead center. Therefore, at the specified time ST, the position of the piston 23 is considerably far from the top dead center. Therefore, it is possible to more reliably prevent the fuel from the final injection from adhering to the piston 23.

[0058] (5) According to the above embodiment, the injection amount of the final injection is 3% or less of the required injection amount. Therefore, the injection amount of the final injection is considerably small. Since the amount of fuel injected in the final injection is small, it is easy to suppress the amount of fuel adhering to the piston 23.

[0059] <Other embodiments> The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs.

[0060] The injection amount of the final injection in the injection control process is not limited to the example of the above embodiment. If the injection amount of the final injection is 10% or less of the required injection amount, it is easy to suppress the amount of fuel that directly adheres to the piston 23 by significantly reducing the injection amount of the final injection. The injection amount of the final injection may be more than 10% of the required injection amount. Furthermore, the injection amount of the final injection may be set to a constant value regardless of the required injection amount.

[0061] The specified time ST may be set on the retard side of the compression top dead center. In other words, the specified time ST may be set on the retard side or larger than -15 degrees. The more the specified time ST is set on the advanced side, the more the CPU 101 Multiple times This increases the opportunities for selecting the injection timing. Therefore, in order to stabilize the combustion during the catalyst warm-up, it is preferable that the specified timing ST is close to "0".

[0062] The specifying process may be omitted. In this case, the specified timing ST may be set to a constant value regardless of the coolant temperature TW. For example, the specified timing ST may be set to a timing 17 degrees retarded from the compression top dead center regardless of the coolant temperature TW.

[0063] If the ignition timing TA is a timing before the specified timing ST (step S14: NO), the number of fuel injections may be determined to be multiple. However, even in this case, in order to prevent fuel from adhering to the piston 23, it is necessary to determine the final injection timing at a timing other than the timing between the timing when the piston 23 is at the top dead center of the compression stroke and the specified timing ST. That is, in the case of this modification, for example, the final injection timing may be set to a timing on the more advanced side than the timing when the piston 23 is at the top dead center of the compression stroke.

[0064] In the injection control process, the final injection timing does not have to be the same as the ignition timing TA. The final injection timing may be determined to be a timing after the specified timing ST and before the ignition timing TA. For example, in the injection control process, the final injection timing may be determined to be the same as the specified timing ST. In this case, the final injection timing will be the most advanced timing among the timings after the specified timing ST and before the ignition timing TA. Therefore, a sufficient amount of time can be ensured between the injection timing and the ignition timing TA for the fuel in the final injection to reach the vicinity of the tip of the spark plug 45. Therefore, Multiple times This makes it easier to stably generate sparks during the final injection.

[0065] In the above embodiment, Multiple timesAlthough the number of injections required to inject the required injection amount from the in-cylinder injection valve 44 is set to two, the number of injections may be three or more. Even if the number of injections is three or more, it is sufficient that the final injection timing, which is the injection timing of the final injection, is a timing after the specified timing ST and before the ignition timing TA.

[0066] The catalyst warm-up condition is not limited to the example in the above embodiment. For example, the catalyst warm-up condition may be that the temperature of the catalyst 52 is equal to or lower than a predetermined temperature. Even in this case, it is possible to determine that the catalyst 52 needs to be warmed up.

[0067] The catalyst warm-up end condition is not limited to the example of the above embodiment. The catalyst warm-up end condition may be, for example, that the integrated value of the intake air amount GA after the start of the internal combustion engine 20 reaches a predetermined amount, or that the elapsed time after the start of the internal combustion engine 20 reaches a predetermined time. In these cases, it can be assumed that the catalyst 52 has been warmed up, and therefore these can be set as conditions for ending the catalyst warm-up process.

[0068] In the above embodiment, the catalyst warm-up process and the injection control process are described using the start-up control as an example. However, the catalyst warm-up process and the injection control process may be performed when the internal combustion engine 20 is restarted.

[0069] The control device 100 is not limited to a device having a CPU 101 and a ROM 103 and executing software processing. For example, the control device 100 may be equipped with a dedicated hardware circuit (such as an ASIC) that performs hardware processing of at least a part of what was processed by software in the above embodiment. That is, the control device 100 may have any of the following configurations (a) to (c). (a) A processing device that executes all of the above processes according to a program, and a program storage device such as a ROM that stores the program. (b) A processing device and a program storage device that execute a part of the above processes according to a program, and a dedicated hardware circuit that executes the remaining processes. (c) A dedicated hardware circuit that executes all of the above processes. Here, there may be a plurality of software execution devices having a processing device and a program storage device, and a dedicated hardware circuit. [Explanation of symbols]

[0070] 20…Internal combustion engine 23…Piston 24…cylinder 44…In-cylinder injection valve 45…Spark plug 51...Exhaust passage 52...Catalyst 100...Control device

Claims

1. The present invention is applied to an internal combustion engine including: a piston that reciprocates within a cylinder; an in-cylinder injection valve that injects fuel into the cylinder; an ignition plug that ignites the mixture in the cylinder; an exhaust passage through which exhaust gas from the cylinder flows; and a catalyst provided in the exhaust passage, a catalyst warm-up process for accelerating the warm-up of the catalyst by retarding the ignition timing of the spark plug from the top dead center of the compression stroke; an injection control process for determining the number of injections required for injecting the required injection amount from the direct injection valve when the amount of fuel provided for one combustion is a required injection amount, and for determining the injection timing of each injection; When the final fuel injection timing determined by the injection control process is the final injection timing, In the injection control process, When the ignition timing becomes more retarded than a predetermined timing that is predetermined as a timing more retarded than the compression top dead center during the catalyst warm-up process and the number of injections is determined to be a plurality of times, the final injection timing is set to a timing after the predetermined timing and before the ignition timing. A control device for an internal combustion engine.

2. In the injection control process, the final injection timing is determined to be the same as the ignition timing. The control device for an internal combustion engine according to claim 1.

3. In the injection control process, the final injection timing is determined to be the same as the specified timing. The control device for an internal combustion engine according to claim 1.

4. A process is further performed to determine the specified timing to be more advanced as the cooling water temperature of the internal combustion engine decreases. The control device for an internal combustion engine according to claim 2.

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