JP2019163749A - Control device of internal combustion engine - Google Patents

Abstract

To provide a control device of an internal combustion engine which can suppress the erroneous detection of knocking by suppressing a piston hit sound.SOLUTION: A control device 60 of an internal combustion engine 10 retards ignition timing when knocking is detected, and advances the ignition timing when the knocking is not detected. Then, when an engine cooling water temperature is within a specified temperature range in which a piston hit sound is generated, the control device 60 sets the ignition timing so as to be retarded more than prescribed ignition timing at which the piston hit sound can be suppressed or so as to be the same as the prescribed ignition timing, even if the knocking is not detected.SELECTED DRAWING: Figure 4

Description

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

  For example, Patent Literature 1 discloses an ignition control device for an internal combustion engine. This ignition control device executes ignition timing learning for low temperature when the cooling water temperature of the internal combustion engine is lower than the temperature threshold. In this ignition timing learning, the retardation of the ignition timing is limited as compared with the ignition timing learning for non-low temperature. For this reason, when the temperature is low, an erroneous retardation of the ignition timing is suppressed. Patent Document 1 discloses that noise generated between a piston and a cylinder inner wall is mistakenly detected as knocking as a cause of erroneous retardation.

JP 2013-087624 A JP2013-096301A JP 2008-057487 A

  The ignition timing control described in Patent Document 1 does not suppress piston hitting sound that occurs when the piston and the cylinder inner wall come into contact with each other. That is, this ignition timing control cannot suppress erroneous detection that the piston sound is knocking.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a control device for an internal combustion engine that can suppress erroneous detection of knocking by suppressing piston hitting sound.

The control apparatus for an internal combustion engine according to the present invention retards the ignition timing when knocking is detected, and advances the ignition timing when knocking is not detected.
When the engine cooling water temperature is within a specific temperature range where piston hitting sound is generated, the control device detects the piston hitting sound from a predetermined ignition timing even when knocking is not detected. Is also retarded or the ignition timing is set to be the same as the predetermined ignition timing.

  According to the present invention, when the engine coolant temperature is within a specific temperature range where piston hitting sound is generated, the engine coolant temperature is retarded from or equal to the predetermined ignition timing capable of suppressing piston hitting sound. The ignition timing is set so that Thereby, since a piston hitting sound can be suppressed, the erroneous detection of knocking resulting from the piston hitting sound can be suppressed.

It is a figure for demonstrating the structure of the system which concerns on Embodiment 1 of this invention. It is an image figure of piston hitting sound generation. It is a figure for demonstrating the suppression effect of the piston hitting sound by an ignition delay angle. It is a flowchart which shows the routine of the process regarding the ignition delay control for the piston hit sound suppression which concerns on Embodiment 1 of this invention. It is a figure showing an example of the specific range used by the process of step S102. It is a flowchart which shows the routine of the process regarding the ignition retard control for the piston hit sound suppression which concerns on the modification of Embodiment 1 of this invention. It is a flowchart which shows the routine of the process regarding the ignition delay control for the piston hit sound suppression which concerns on Embodiment 2 of this invention. It is a flowchart which shows the routine of the process regarding the ignition delay control for the piston hit sound suppression which concerns on Embodiment 3 of this invention. It is a figure for demonstrating the setting method of the ignition delay range this time specified by the engine load KL and the engine speed NE. It is a figure for demonstrating the setting method of the ignition retard range of this time specified by engine coolant temperature and external temperature.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. In the embodiment shown below, when the number of each element is mentioned, the number, quantity, range, range, etc., unless otherwise specified or clearly specified in principle, the number mentioned. However, the present invention is not limited to this. Further, the structures, steps, and the like described in the embodiments below are not necessarily essential to the present invention unless otherwise specified or clearly specified in principle.

1. Embodiment 1
First, with reference to FIGS. 1-6, Embodiment 1 of this invention and its modification are demonstrated.

1-1. System Configuration FIG. 1 is a diagram for explaining a system configuration according to Embodiment 1 of the present invention. The system shown in FIG. 1 includes a spark ignition type internal combustion engine 10. The internal combustion engine 10 is mounted on a vehicle, for example, and is used as a power source. The internal combustion engine 10 is an in-line four-cylinder engine as an example.

  FIG. 1 shows the configuration of the internal combustion engine 10 with a cooling system as the center. In the cylinder block 12 and the cylinder head 14 corresponding to the main body of the internal combustion engine 10, water jackets 16 and 18 through which engine coolant for cooling the main body flows are formed, respectively. Heat exchange is performed between the engine coolant flowing through the water jackets 16 and 18 and the cylinder block 12 and the cylinder head 14.

  An electric water pump (electric WP) 20 for pumping engine cooling water is disposed in the vicinity of the cooling water inlet of the water jacket 16 formed in the cylinder block 12. According to the electric WP20, the flow rate of the engine coolant can be variably controlled by duty control. The engine cooling water flowing into the cylinder block 12 from the cooling water inlet of the water jacket 16 flows into the cylinder head 14 after passing through the water jacket 16 including the passage between bores (drill path). In the cylinder head 14, the engine coolant flows from the intake side to the exhaust side (exhaust cooling unit 22) in the water jacket 18 including the exhaust valve flow path (Ex-J valve WJ).

  Connected to one of the cooling water outlets of the water jacket 18 is a return flow path 24 through which engine cooling water returning from the cylinder head 14 and returning to the electric WP 20 flows. An EGR cooler (EGR / C) 26 is disposed near the end of the return flow path 24 on the cylinder head 14 side. The return flow path 24 is formed so that the engine coolant that has exited the EGR cooler 26 once flows into the cylinder head 14 and then is sucked into the electric WP 20. An electronic thermostat 28 is disposed near the end of the return flow path 24 on the electric WP 20 side.

  A branch flow path 30 is connected to the return flow path 24. The branch flow path 30 branches from the return flow path 24 at the cooling water outlet of the EGR cooler 26, and merges with the return flow path 24 again at a site after the engine cooling water flows out of the cylinder head 14 again. An EGR valve (EGR / V) 32 and a throttle 34 are arranged in the branch flow path 30 in order from the upstream side of the engine cooling water.

  The water jacket 18 includes two cooling water outlets located on the downstream side of the exhaust cooling unit 22. One of these cooling water outlets is connected to a radiator upstream flow path 38 through which engine cooling water flowing into the radiator 36 flows. Further, the radiator downstream flow path 40 through which the engine cooling water that has been radiated by the radiator 36 flows is connected to the electronic thermostat 28. The electronic thermostat 28 can arbitrarily adjust the ratio of engine cooling water flowing through the return flow path 24 and engine cooling water flowing through the radiator 36.

  The engine cooling water is configured to be able to circulate through various other devices, that is, an oil cooler 42, a heater (for heating the vehicle interior) 44, and an ATF cooler 46. Specifically, an oil cooler flow path 48 formed so that the engine cooling water flows through the oil cooler 42 and then returns to the exhaust cooling unit 22 of the cylinder head 14 is connected to the cooling water outlet of the water jacket 16. Yes. Further, the other of the two cooling water outlets located on the downstream side of the exhaust cooling unit 22 has a device flow path formed so that the engine cooling water flows to the return flow path 24 after flowing through the heater 44 and the ATF cooler 46. 50 is connected. More specifically, the device flow path 50 includes a heater flow path 50 a for the heater 44 and an ATF cooler flow path 50 b for the ATF cooler 46. The heater flow path 50 a is formed so that the engine coolant passes through the heater 44 and merges with the return flow path 24 in the vicinity of the outlet of the EGR cooler 26. The ATF cooler flow path 50 b is formed so that the engine coolant passes through the ATF cooler 46 and then merges with the return flow path 24 at a portion after exiting the cylinder head 14 again. In addition, electromagnetic valves 52 and 54 for opening and closing the heater passage 50a and the ATF cooler passage 50b are arranged, respectively. Furthermore, an engine water temperature sensor 56 that outputs a signal corresponding to the temperature of the engine coolant is disposed at the end of the device flow path 50 on the cylinder head 14 side.

  The system according to the present embodiment includes a control device 60 for controlling the internal combustion engine 10. The control device 60 is an ECU (Electronic Control Unit) having at least one processor, at least one memory, and an input / output interface. The input / output interface captures sensor signals from various sensors mounted on the internal combustion engine 10 and outputs operation signals to various actuators for controlling the operation of the internal combustion engine 10. The various sensors include an air flow sensor 62, a crank angle sensor 64, an outside air temperature sensor 66, and a knock sensor 68. The air flow sensor 62 detects a signal corresponding to the intake air flow rate Ga. The crank angle sensor 64 outputs a signal corresponding to the crank angle. The control device 60 can calculate the engine rotation speed NE using this signal. The outside air temperature sensor 66 outputs a signal corresponding to the outside air temperature. The knock sensor 68 is attached to the outer wall of the cylinder block 12 and measures the vibration of the cylinder block 12 to detect knocking. The various actuators described above include an ignition device 70 together with the electric WP 20, the electronic thermostat 28, the EGR valve 32, the throttle 34, and the electromagnetic valves 52 and 54 described above. The ignition device 70 is configured to be able to control the ignition timing for each cylinder.

  In the memory of the control device 60, various programs and various data (including a map) for controlling the internal combustion engine 10 are stored. Various functions of the control device 60 are realized by the program stored in the memory being executed by the processor. For example, ignition timing control by operating the ignition device 70 is one of the functions realized by executing a program. In addition, the control apparatus 60 may be comprised from several ECU.

1-2. Ignition Timing Control Ignition timing control performed by the control device 60 includes ignition timing control by a knock control system (KCS) and ignition timing control (ignition delay control) based on detection of piston striking sound.

1-2-1. Ignition Timing Control by KCS The KCS basically includes a knock sensor 68, an ignition device 70, and a control device 60. According to KCS, when knocking is detected using the knock sensor 68, the ignition timing is retarded, and when knocking is not detected, the ignition timing is advanced.

1-2-2. Piston hammering force The piston that reciprocates in the piston / crank mechanism is subjected to a force (so-called side thrust) that presses the side surface of the piston against the cylinder wall due to the inclination of the connecting rod. Due to the influence of the side thrust, the piston and the inner wall of the cylinder come into contact with each other, so that a piston hitting sound may be generated. When a piston hitting sound is generated in an internal combustion engine using KCS, not only the vibration noise performance is lowered, but also the following problems occur.

  According to the system configuration shown in FIG. 1, by stopping the operation of the electric WP 20 during engine warm-up and almost stopping the flow of water in the water jackets 16 and 18, warm-up is promoted and fuel efficiency is improved. Can be achieved (water stop control). The water stop control can be performed by switching the flow path using the multi-function valve instead of the electric WP20. However, when such water stop control is performed, the upper part of the cylinder head 14 is biased to a high temperature due to the influence of heat generated by combustion. As a result, piston striking noise is generated by the deformation of cylinders other than the end (# 2 and # 3 cylinders other than the end in the example of the internal combustion engine 10 having four cylinders # 1 to # 4 from one end). It becomes easy.

  FIG. 2 is an image diagram of generation of piston hitting sound. FIG. 2 illustrates the # 3 cylinder (same as the # 2 cylinder) which is one of the cylinders other than the end. “Behavior 1” in FIG. 2 indicates the piston 72 immediately before the compression top dead center. “Behavior 2” indicates a state in which the above-described side thrust acts on the piston 72 that has reached the compression top dead center while tilting clockwise in FIG. 2. Regarding the cylinder inner wall 74, the side marked “Th” in FIG. 2 corresponds to the “thrust side” that receives the side thrust immediately after the compression top dead center, and the side marked “ATh” It corresponds to the “anti-thrust side” which is the opposite side.

  “Behavior 3” represents a state in which the lower part of the piston 72 which has started to descend after the compression top dead center has collided with the cylinder inner wall 74 on the thrust side by the side thrust (collision 1). “Behavior 4” indicates a state in which the piston 72 is rotated counterclockwise by the side thrust with the lower part of the collision as a fulcrum. “Behavior 5” represents a state in which the entire piston 72 collides with the cylinder inner wall 74 on the thrust side as a result of the counterclockwise rotation (collision 2).

  When a piston hitting sound is generated along with the collisions 1 and 2, vibrations derived from the collisions 1 and 2 are generated on the outer wall of the cylinder block 12 as shown in FIG. The knock sensor 68 detects such vibration as noise. And as shown in FIG. 3, the generation time of the vibration accompanied with the piston hitting sound is a time immediately after the compression top dead center, and overlaps with the generation time of knocking. As a result, the KCS may erroneously detect that knocking has occurred due to the occurrence of vibration accompanied by piston hitting sound. In order to avoid such erroneous detection, it is conceivable to suppress the occurrence of piston hitting sound. Specifically, in a situation where it is desired to improve engine warm-up by water stop control, the temperature difference between the upper and lower sides of the main body of the internal combustion engine 10 is suppressed by securing a certain amount of cooling water flow, and piston hitting noise is generated. It is conceivable to suppress this. However, when such measures are taken, the effect of water stop control is diminished, and the fuel efficiency that can be improved by promoting engine warm-up is sacrificed.

1-2-3. FIG. 3 is a diagram for explaining the effect of suppressing the piston hitting sound by the ignition delay angle. The vertical axis in FIG. 3 represents the intensity of vibration detected by the knock sensor 68. FIG. 3 shows the waveform having the largest peak value extracted from the waveforms of vibration intensity acquired for a predetermined number of cycles under the situation where piston hitting sound is generated.

  The left diagram in FIG. 3 shows the waveform when the optimum ignition timing (MBT) is selected, and the right diagram shows the timing when the ignition timing is retarded from the MBT under the same engine operating conditions (for example, , MBT, 3 ° CA retardation). A straight line L in FIG. 3 corresponds to an allowable limit of vibration intensity for suppressing erroneous detection of the knock sensor 68.

  In the example shown in FIG. 3, when the ignition timing is MBT, the peak value of the vibration intensity exceeds the allowable limit (straight line L) at the timing immediately after the compression top dead center. On the other hand, when a predetermined ignition timing retarded from the MBT (for example, 3 ° CA retarded from the MBT) is used, the peak value of the vibration intensity immediately after the compression top dead center falls below the allowable limit. That is, noise superimposed on knock sensor 68 is reduced. This is because the peak value of the combustion pressure is lowered by retarding the ignition timing, and as a result, the piston sound is suppressed.

  In this embodiment, a situation that is subject to ignition delay control for suppressing piston hitting sound is, for example, during engine warm-up in which water stop control that contributes to piston hitting sound is performed. The piston hitting sound is considered to occur within a specific engine coolant temperature range (for example, 60 ° C. to 75 ° C.). For this reason, the execution condition of this ignition retardation control first includes that the engine coolant temperature is within the specific temperature range.

  Further, it is considered that the piston hitting sound is likely to occur within the range of the specific engine load KL (or intake air flow rate Ga) and the engine rotation speed NE. For this reason, it is desirable that the execution condition of the ignition retard control includes that the engine load KL and the engine speed NE are in a specific range (for example, FIG. 5 described later). Therefore, in the present embodiment, not only the engine coolant temperature but also the engine load KL and the engine speed NE are used as parameters to specify the execution conditions for the ignition retard control. However, the execution condition of the ignition retard control may be only that the engine coolant temperature is within a specific temperature range.

  In addition, the ignition retard control is intended for piston hitting sound resulting from the execution of the water stop control described above. For this reason, this ignition delay angle control is executed for the cylinders (that is, the specific cylinders (# 2, # 3) other than the end) where the piston hitting sound is likely to occur. The ignition retard control can be performed, for example, at the end cylinder, even when the piston hitting sound resulting from the execution of the water stop control is targeted. May also be executed as a target.

  In the ignition delay control, the ignition timing is set to be retarded or the same as the “predetermined ignition timing” that can suppress the piston hitting sound. In other words, the ignition timing is set so as not to advance more than the predetermined ignition timing. Further, the predetermined ignition timing here is, for example, a value delayed by a predetermined amount (3 ° CA) from the MBT described with reference to FIG. The retard amount of the predetermined ignition timing with respect to MBT may be a uniform value (for example, 3 ° CA), or may be engine coolant temperature, engine load KL, engine speed NE, and other It may be a variable value according to the factor.

1-2-4. FIG. 4 is a flowchart showing a routine of a process related to the ignition delay control for suppressing the piston hitting sound according to the first embodiment of the present invention. The control device 60 repeatedly executes the processing of this routine at a predetermined control cycle during engine warm-up after engine startup.

  In the routine shown in FIG. 4, first, the control device 60 determines whether the engine coolant temperature detected by the engine coolant temperature sensor 56 is within a specific temperature range (for example, 60 ° C. to 75 ° C.) in which piston hitting sound is generated. It is determined whether or not (step S100). As a result, when the determination result is negative, the control device 60 ends the current processing cycle.

  On the other hand, if the determination result of step S100 is affirmative, the process proceeds to step S102. In step S102, the control device 60 determines whether or not the engine load KL and the engine rotation speed NE are within a specific range. FIG. 5 is a diagram illustrating an example of the specific range used in the process of step S102. In FIG. 5, as an example, the specific range (ignition delay range) that is subject to ignition delay control is set so that the engine load KL is 30 to 70% and the engine rotation speed NE is 2000 to 4000 rpm. Has been. The specific range in terms of the engine load KL and the engine rotational speed NE can be specified by performing a test or the like in advance as a range in which piston hitting sound is generated. Note that the boundary of the specific range (ignition delay range) does not have to be rectangular as shown in FIG. 5, and may be specified by, for example, an iso-output line of the internal combustion engine 10. The engine load (load factor) KL can be calculated based on, for example, the intake air flow rate Ga, the engine rotational speed NE, and the like.

  If the determination result of step S102 is negative, the control device 60 ends the current processing cycle. On the other hand, if the determination result of step S102 is affirmative, the process proceeds to step S104. In step S104, the control device 60 performs ignition retard control for specific cylinders other than the end (# 2, # 3 in the internal combustion engine 10). Specifically, the ignition timing is set to be the same as or retarded from the predetermined ignition timing. For this reason, when the current target ignition timing is a value advanced from the predetermined ignition timing, the target ignition timing is corrected to be the same as the predetermined ignition timing. On the other hand, when the current target ignition timing is the same as the predetermined ignition timing or a value on the retard side, the target ignition timing is not changed.

1-3. Effect As described above, according to the present embodiment, when the engine coolant temperature is within the specific temperature range where the piston hitting sound is generated, the engine load KL and the engine rotational speed NE are within the specific range. On the condition of this, the ignition retard control is executed. According to this ignition delay control, the ignition timing is set so as to be retarded or the same as the predetermined ignition timing capable of suppressing the piston hitting sound. Thereby, since a piston hitting sound can be suppressed, the erroneous detection of knocking resulting from the piston hitting sound can be suppressed.

1-4. In the first embodiment described above, the engine load KL and the engine rotation speed NE are used together with the engine coolant temperature as parameters that define the execution conditions of the ignition retard control. However, in addition to these parameters, as parameters that can contribute to piston hitting sound, for example, the rising gradient of the outside air temperature or the engine coolant temperature can be considered. Therefore, the execution condition of the ignition retard control may be defined in consideration of these parameters as in the routine shown in FIG. As a result, it is possible to more appropriately determine the situation in which the ignition retard control is to be truly executed.

  FIG. 6 is a flowchart showing a routine of processing relating to ignition delay control for suppressing piston hitting sound according to a modification of the first embodiment of the present invention. The processes in steps S100 to S104 in the routine shown in FIG. 6 are as described in the first embodiment.

  In the routine shown in FIG. 6, the control device 60 proceeds to step S200 when the determination result of step S102 is affirmative. In step S200, control device 60 determines whether or not the outside air temperature is within a specific temperature range. Such a specific temperature range of the outside air temperature can be specified by performing a test or the like in advance as a temperature range in which piston hitting sound is generated. The outside air temperature used for this determination may be a detection value of the outside air temperature sensor 66 or may be an engine coolant temperature at the time of engine start detected by the engine water temperature sensor 56.

  If the determination result of step S200 is negative, the control device 60 ends the current processing cycle. On the other hand, if the determination result of step S200 is affirmative, the process proceeds to step S202. In step S202, the control device 60 determines whether or not the rising gradient of the engine coolant temperature during a predetermined time is greater than a predetermined threshold value. This is because, when the rising gradient of the engine coolant temperature is large, piston hitting sound is easily generated due to cylinder deformation.

  If the determination result of step S202 is negative, the control device 60 ends the current processing cycle. On the other hand, when the determination result of step S202 is affirmative, the control device 60 performs ignition retard control (step S104).

  Further, as another example of the execution condition of the ignition retard control, instead of the example shown in FIG. 6, at least one of steps S200 and S202 may be used together with steps S100 and S102. Alternatively, as another example of the execution condition, at least one of steps S200 and S202 may be used together with step S100 instead of step S102.

2. Embodiment 2
Next, a second embodiment of the present invention will be described with reference to FIG. In the following description, the configuration shown in FIG. 1 is used as an example of the configuration of the system according to the second embodiment. The same applies to the third embodiment described later.

2-1. Ignition Timing Control The ignition timing control according to the present embodiment is different from the ignition delay control according to the first embodiment in the execution conditions of the ignition delay control for suppressing piston hitting sound. That is, in this embodiment, as this execution condition, the engine coolant temperature is within a specific temperature range, and the knock sensor 68 has detected a piston hitting sound. The execution condition may be obtained by adding at least one of the determination conditions of steps S102, S200, and S202 described above to these two conditions.

2-2. FIG. 7 is a flowchart showing a routine of a process related to ignition delay control for suppressing piston hitting sound according to Embodiment 2 of the present invention. The processing in steps S100 and S104 in the routine shown in FIG. 7 is as described in the first embodiment.

  In the routine shown in FIG. 7, the control device 60 proceeds to step S300 when the determination result of step S100 is affirmative. In step S300, control device 60 determines whether knock sensor 68 has detected a piston hitting sound. As described above, when the piston hitting sound is generated, the outer wall of the cylinder block 12 vibrates, so that the vibration is superimposed on the output of the knock sensor 68. For this reason, for example, by setting in advance a threshold value that can discriminate that the vibration caused by the piston hitting sound is superimposed, the piston hitting sound can be detected based on the output of the knock sensor 68. In addition, as long as it is another sensor which can detect a piston hitting sound, such a sensor may be used instead of the knock sensor 68 for determination of this step S300.

  If the determination result of step S300 is negative, the control device 60 ends the current processing cycle. On the other hand, when the determination result of step S300 is affirmative, the control device 60 executes ignition retard control (step S104).

2-3. Effect According to the ignition retard control according to the second embodiment described above, the condition for truly executing the ignition retard control is appropriately determined using the detection result of the piston hitting sound using the knock sensor 68. can do. In this embodiment, not only the detection result of the piston hitting sound using the knock sensor 68 but also the fact that the engine coolant temperature is within a specific temperature range where the piston hitting sound is used as an execution condition. . Thereby, the detection of the piston hitting sound by the knock sensor 68 can be performed more accurately.

3. Embodiment 3
Next, Embodiment 3 of the present invention will be described with reference to FIGS.

3-1. Ignition Timing Control Ignition timing control according to the present embodiment is different from the ignition delay control according to the second embodiment in that the following contents are added with respect to the ignition delay control for suppressing piston hitting sound. ing. That is, in the present embodiment, the ignition retard control is executed according to the same execution conditions as in the second embodiment. Further, in the present embodiment, even when the internal combustion engine 10 is operated under conditions (engine load KL, engine rotation speed NE, engine coolant temperature, and outside air temperature) that are similar to those at the time when the ignition retard control was performed last time, Ignition retarding control is executed.

3-2. FIG. 8 is a flowchart showing a routine of processing relating to ignition delay control for suppressing piston hitting according to Embodiment 3 of the present invention. The routine shown in FIG. 8 is executed in parallel with the routine shown in FIG. 7 of the second embodiment described above.

  In the routine shown in FIG. 8, the control device 60 has at least one of the engine operating range specified by the engine load KL and the engine rotational speed NE and the temperature range specified by the engine coolant temperature and the outside air temperature. It is determined whether or not it is within the current ignition delay range (step S400).

  FIG. 9 is a diagram for explaining a setting method of the current ignition delay range specified by the engine load KL and the engine speed NE. In step S400, as shown in FIG. 9, the control device 60 sets the current ignition delay range from the viewpoint of the engine load KL and the engine rotational speed NE with the previous retard execution point as the center. In the example shown in FIG. 9, the range of ± 5% of the engine load KL at the previous retarding execution point and the range of ± 5000 rpm of the engine rotational speed NE at the previous retarding execution point are the current ignition retardation range. Set as The control device 60 stores the values of the engine load KL and the engine rotational speed NE when the ignition delay is performed every time the ignition delay is performed according to the routine shown in FIG. It shall be.

  FIG. 10 is a diagram for explaining a method for setting the current ignition delay range specified by the engine coolant temperature and the outside air temperature. In step S400, the control device 60 further sets the current ignition delay range from the viewpoint of the engine coolant temperature and the outside air temperature with the previous delay angle execution point as the center, as shown in FIG. In the example shown in FIG. 10, the range of ± 5 ° C. of the engine coolant temperature at the previous retarding execution point and the range of ± 1 ° C. of the outside air temperature at the previous retarding execution point are the current ignition retardation range. Set as Note that each time the ignition delay is performed according to the routine shown in FIG. 7, the control device 60 stores the values of the engine coolant temperature and the outside air temperature when the ignition delay is performed as the previous retardation execution point. It shall be.

  If the determination result of step S400 is negative, the control device 60 ends the current processing cycle. On the other hand, when the determination result of step S400 is affirmative, the control device 60 executes ignition retard control (step S104).

3-3. Effect According to the ignition retard control according to the third embodiment described above, various conditions (such as the engine load KL and the engine coolant temperature) when the ignition retard control is performed last time are learned. Then, when the internal combustion engine 10 is operated under conditions close to the previous time (that is, conditions in which piston strike noise is likely to occur as in the previous time), the ignition delay control is executed. For this reason, piston hitting sound can be more effectively suppressed.

  In addition, the examples described in the above-described embodiments and other modifications may be appropriately combined within a possible range other than the explicit combination, and may be within a scope not departing from the gist of the present invention. Various modifications may be made.

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 12 Cylinder block 14 Cylinder head 16, 18 Water jacket 20 Electric water pump (electric WP)
56 Engine water temperature sensor 60 Control device 62 Air flow sensor 64 Crank angle sensor 66 Outside air temperature sensor 68 Knock sensor 70 Ignition device 72 Piston 74 Cylinder inner wall

Claims (1)

A control device for an internal combustion engine that retards the ignition timing when knocking is detected and advances the ignition timing when knocking is not detected,
When the engine cooling water temperature is within a specific temperature range where piston hitting sound is generated, the control device detects the piston hitting sound from a predetermined ignition timing even when knocking is not detected. The ignition timing is set so as to be retarded or the same as the predetermined ignition timing.

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