JP2012102677A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve detecting accuracy of the existence of abnormal combustion by a knocking sensor.SOLUTION: In abnormal combustion detection for detecting abnormal combustion in a plurality of respective cylinders in response to output of a knock sensor in a vibration detecting period set in the plurality of respective cylinders, first of all, a discrimination is made on whether a present operation area of an internal combustion engine is an area which can cause the abnormal combustion. Next, when discriminated as being the area which can cause the abnormal combustion, a discrimination is made on whether a vibration detecting period of one cylinder and an injection period of fuel from a fuel injection valve in the other cylinder overlap with each other among the plurality of cylinders. When discriminated as overlapping between the vibration detecting period of the one cylinder and the injection period of the other cylinder, the injection period of at least the other cylinder is adjusted in the timing for reducing overlapping with the vibration detecting period of the one cylinder.

Description

  The present invention relates to a control device for an internal combustion engine, and in particular, is suitable as a control device for an internal combustion engine having means for detecting vibrations of the internal combustion engine.

  Patent Document 1 discloses an internal combustion engine including a knock control system. This knock control system has means for determining whether the vibration detected by the sensor for detecting vibration is due to knocking or preignition. Specifically, in this system, when pressure vibration in the cylinder is detected, first, the ignition timing is retarded. When knocking does not converge due to this ignition timing retardation and the air-fuel ratio is smaller than before the retardation, it is determined that the vibration is due to pre-ignition.

JP-A-11-247750 JP 2010-133367 A

  The knock sensor is generally installed near the center of the cylinder block, and one knock sensor is shared for each cylinder group. Here, vibration due to abnormal combustion of the internal combustion engine such as pre-ignition occurs at a timing near the ignition timing. Therefore, in general, in the detection of vibration due to abnormal combustion, a period near the occurrence of abnormal combustion is set as a vibration detection period for each cylinder, and abnormal combustion of each cylinder is detected according to the output of the knock sensor during this vibration detection period. Presence / absence is determined. As a result, the occurrence of abnormal combustion and the identification of the generated cylinder can be performed by one sensor.

  However, it is conceivable that the vibration detection period set for each cylinder as described above overlaps with the fuel injection periods of the other cylinders. In this case, the fuel injection valve is driven in another cylinder during the vibration detection period of a certain cylinder. When the fuel injection valve is driven in another cylinder, the vibration caused by the driving can be a noise for vibration detection of abnormal combustion in the cylinder in the vibration detection period at this time. Therefore, it is conceivable that the drive noise of the fuel injection valve becomes a factor that reduces the determination accuracy of the presence or absence of abnormal combustion in the cylinder in the vibration detection period.

  In particular, in the case of a system in which one knock sensor is shared, vibrations that occur in cylinders far from the knock sensor placement position are difficult to be transmitted to the knock sensor. For this reason, other vibrations such as driving noise of the fuel injection valve are likely to be noise, and it is considered that the determination accuracy of the presence or absence of abnormal combustion is reduced by this noise.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an improved control device for an internal combustion engine in order to improve the detection accuracy of the presence or absence of abnormal combustion by a knocking sensor.

In order to achieve the above object, the first invention provides
A fuel injection valve disposed in each of the plurality of cylinders of the internal combustion engine and injecting fuel directly into each of the plurality of cylinders;
A knock sensor that is installed in common among at least two of the plurality of cylinders and generates an output corresponding to vibration;
An internal combustion engine control device comprising:
Abnormal combustion detection means for detecting abnormal combustion in each of the plurality of cylinders according to an output of the knock sensor in a vibration detection period set for each of the plurality of cylinders;
An operation region determination means for determining whether or not the current operation region of the internal combustion engine is a region where abnormal combustion can occur;
Of the plurality of cylinders, when the operation region determination unit determines that the region is in a region where abnormal combustion can occur, the vibration detection period of one cylinder and the fuel injection valve in another cylinder Period determining means for determining whether or not the fuel injection period overlaps;
When it is determined that the vibration detection period of the one cylinder and the injection period of the other cylinder overlap, at least the injection period of the other cylinder overlaps with the vibration detection period of the one cylinder. Injection period adjusting means for adjusting to timing;
Is provided.

  In a second aspect based on the first aspect, the injection period adjusting means retards the injection period of the other cylinder.

In a third aspect based on the first aspect, the internal combustion engine includes a port injection valve for injecting fuel to each intake port communicating with each of the plurality of cylinders.
Adjustment determination for determining whether or not the injection period and the vibration detection period of the one cylinder can be adjusted within an allowable range by retarding or advancing the injection period of the other cylinder Means,
Advance or retard the injection period of the other cylinder when it is determined that the overlap between the injection period of the other cylinder and the vibration detection period of the one cylinder cannot be adjusted to be within an allowable range. An injection period shortening setting means for shortening the injection period of the other cylinder in a range in which an overlap between the vibration detection period of the one cylinder and the injection period of the other cylinder can be allowed.
A deficient fuel amount calculating means for calculating a fuel amount deficient due to the shortening of the injection period when the injection period of the other cylinder is shortened by the injection period shortening setting means;
Port injection amount setting means for setting the fuel injection amount from the port injection valve by adding the insufficient fuel amount;
Is further provided.

Moreover, 4th invention is set in 1st invention,
Adjustment determination for determining whether or not the injection period and the vibration detection period of the one cylinder can be adjusted within an allowable range by retarding or advancing the injection period of the other cylinder Means further comprising
The injection period consists of a divided injection period divided into two or more and a pause period between them.
The injection adjusting means includes
When it is determined that the overlap between the injection period of the other cylinder and the vibration detection period of the one cylinder cannot be adjusted to be within an allowable range, the pause period of the other cylinder is lengthened and the pause Adjustment is made so that the period overlaps at least a part of the vibration detection period of the one cylinder.

The fifth invention is the first invention, wherein
Adjustment determination for determining whether or not the injection period and the vibration detection period of the one cylinder can be adjusted within an allowable range by retarding or advancing the injection period of the other cylinder Means further comprising
The injection period consists of a divided injection period divided into two or more and a pause period between them.
The injection adjusting means includes
When it is determined that adjustment cannot be made so that an overlap between the injection period of the other cylinder and the vibration detection period of the one cylinder falls within an allowable range, the injection period is reduced by shortening the pause period of the other cylinder. The period is shortened, and adjustment is performed so that the overlap between the vibration detection period of the one cylinder and the injection period of the other cylinder falls within an allowable range.

  A sixth invention is the cylinder according to any one of the first to fifth inventions, wherein the one cylinder is arranged at a position farthest from the knock sensor.

Further, in a seventh invention according to any one of the first to fifth inventions, the injection period adjusting means includes:
When it is determined that the vibration detection period of the one cylinder and the injection period of the other cylinder overlap, the injection period for all of the plurality of cylinders is set as the vibration detection period of any of the plurality of cylinders. Adjust the timing so that there is less overlap with.

Further, an eighth invention is any one of the first to seventh inventions,
The internal combustion engine includes a plurality of cylinder groups each having a plurality of cylinders,
The knock sensor is installed for each cylinder group,
The one cylinder and the other cylinder are cylinders arranged in the same cylinder group.

  According to the first invention, when the operation region of the internal combustion engine is a region where abnormal combustion can occur, it is determined that the vibration detection period of one cylinder of the internal combustion engine and the injection period of other cylinders overlap. Then, at least the injection period of other cylinders is adjusted to a timing at which the overlap with the vibration detection period of one cylinder is reduced. Thereby, the influence of the drive noise in the vibration detection of one cylinder can be reduced. Therefore, in an operating state in which abnormal combustion can occur, vibrations caused by abnormal combustion can be detected more accurately, and the presence or absence of abnormal combustion can be determined with higher accuracy.

  According to the second invention, when the vibration detection period of one cylinder and the injection period of the other cylinder overlap, the injection period of the other cylinder is retarded. As a result, the overlap between the vibration detection period of one cylinder and the injection period of the other cylinders can be reliably reduced.

  According to the third invention, when the injection period of another cylinder is retarded or advanced, the overlap between the injection period and the vibration detection period of one cylinder cannot be adjusted within an allowable range. The fuel injection period is shortened, and fuel that is insufficient due to the shortening of the injection period is injected from the port injection valve. Thereby, the overlap with the injection period of the other cylinder in the vibration detection period of one cylinder can be reliably reduced to an allowable range. Therefore, it is possible to suppress the occurrence of vibration due to driving of the fuel injection valves of other cylinders during the vibration detection period of one cylinder, and it is possible to more appropriately detect vibration due to abnormal combustion.

  According to the fourth and fifth inventions, when the injection period of another cylinder is retarded or advanced, the injection period and the vibration detection period of one cylinder cannot be adjusted to be within the allowable range. The rest period between the divided injection periods obtained by dividing the injection periods of the other cylinders into two or more is adjusted. As a result, the overlap between the injection period of the other cylinder and the vibration detection period of one cylinder can be easily reduced, and vibration due to abnormal combustion can be detected more reliably.

  By the way, especially in the cylinder far from the knock sensor, the vibration generated by the abnormal combustion is difficult to be transmitted, and the detection accuracy is easily lowered due to the influence of the vibration caused by the drive of the fuel injection valve of the other cylinder. In this regard, according to the sixth invention, one cylinder is a cylinder disposed farthest from the knock sensor, and the overlap of the vibration detection period of this cylinder with the injection period of other cylinders is reduced. To be controlled. Therefore, high detection accuracy can be maintained for the presence or absence of abnormal combustion even in a cylinder disposed at a position far from the knock sensor.

  According to the seventh aspect, when it is determined that the vibration detection period of one cylinder and the injection period of the other cylinder overlap, the injection periods of all the cylinders are the vibration detection period of any cylinder. Is adjusted to a timing at which the overlap of the images decreases. As a result, for all the cylinders, vibration due to driving of the fuel injection valves of the other cylinders during the vibration detection period can be suppressed, and vibration due to abnormal combustion can be detected with higher accuracy.

  According to the eighth invention, when a plurality of cylinder groups having a plurality of cylinders are provided, the adjustment when the injection period and the vibration detection period overlap can be performed only between the same cylinder groups. . Therefore, it is possible to adjust the injection period only between cylinders that are considered to be noise when a vibration of a certain cylinder is detected.

It is a figure which shows the system configuration | structure of the internal combustion engine to which the control apparatus of Embodiment 1 of this invention is applied. It is a figure for demonstrating the control in Embodiment 1 of this invention. It is a figure for demonstrating the routine of control which a control apparatus performs in Embodiment 1 of this invention. It is a figure for demonstrating the internal combustion engine to which the control apparatus of Embodiment 2 of this invention is applied. It is a figure for demonstrating the control in Embodiment 2 of this invention. It is a figure for demonstrating the routine of control which a control apparatus performs in Embodiment 2 of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 6. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof is simplified or omitted.

  FIG. 1 is a diagram showing a system configuration of an internal combustion engine to which a control device according to Embodiment 1 of the present invention is applied. The system of FIG. 1 has an internal combustion engine 2. Although only one cylinder 4 of the internal combustion engine 2 is shown in FIG. 1, the internal combustion engine 2 is actually a spark ignition type four-stroke engine having four cylinders # 1 to # 4. The order of ignition of the cylinders in the internal combustion engine 2 is set as # 1 → # 3 → # 4 → # 2.

  A fuel injection valve 6 is attached to each cylinder 4 of the internal combustion engine 2. The fuel injection valve 6 is a direct injection type fuel injection valve that directly injects fuel into each cylinder 4. Each cylinder 4 communicates with an intake port 8 and an exhaust port 10.

  The internal combustion engine 2 has a knock sensor 12. The knock sensor 12 is attached to the cylinder block near the center of the four cylinders, that is, between the # 2 cylinder and the # 3 cylinder. The knock sensor 12 is a sensor that emits an output corresponding to the generated vibration.

  The control system of the internal combustion engine 2 according to the first embodiment includes an ECU (Electronic Control Unit) 20. The ECU 20 is a control device that comprehensively controls the entire system of the internal combustion engine 2. Various actuators such as an actuator of the fuel injection valve 6 are connected to the output side of the ECU 20, and a sensor such as a knock sensor 12 is connected to the input side of the ECU 20. The ECU 20 receives signals from the sensors and operates the actuators according to a predetermined control program. There are many actuators and sensors connected to the ECU 20, but the description thereof is omitted in this specification.

  The ECU 20 determines whether or not abnormal combustion has occurred according to the output of the knock sensor 12 during a predetermined vibration detection period. More specifically, the output of the knock sensor 12 during a vibration detection period for each cylinder, which will be described later, is detected, it is determined whether the output is equal to or higher than a predetermined threshold level, and the output is recognized as being equal to or higher than the threshold level. If it is, it is determined that abnormal combustion has occurred. As a result, the abnormal combustion detecting means of the present invention is realized.

  By the way, vibration due to abnormal combustion such as pre-ignition that leads to self-ignition before the set ignition timing occurs before and after the ignition timing. Therefore, the vibration detection period for detecting abnormal combustion is set to a timing before and after the ignition timing. However, in the case of a four-cylinder internal combustion engine, it is conceivable that the vibration generation timing due to abnormal combustion overlaps with the fuel injection period from the fuel injection valves 6 of other cylinders. In this case, during the vibration detection period, vibration due to driving of the fuel injection valve 6 is transmitted to the knock sensor 12 as noise, so that it is conceivable to reduce the determination accuracy of whether or not vibration has occurred due to abnormal combustion.

  In particular, in the # 1 cylinder and the # 4 cylinder arranged at the end far from the knock sensor 12, vibration generated by abnormal combustion is not easily transmitted to the knock sensor 12. For this reason, it is conceivable that the influence of the drive noise of the fuel injection valve 6 becomes larger in the case of the # 1 cylinder and the # 4 cylinder at the end, and the detection accuracy for abnormal combustion occurring in the end cylinder is lowered.

  Therefore, in the first embodiment, the ECU 20 as the control device increases the detection accuracy of the presence or absence of abnormal combustion when the operation region of the internal combustion engine 2 is in the abnormal combustion generation operation region where abnormal combustion is likely to occur. Therefore, the following control is performed. FIG. 2 is a diagram for illustrating control executed by the ECU 20 as the control device in the first embodiment of the present invention. In FIG. 2, the cylinder number is shown in the leftmost column, and each row represents the stroke of one cycle for each cylinder.

  As shown in FIG. 2, the vibration detection period for detecting abnormal combustion in each cylinder is a time when vibration due to abnormal combustion is assumed to be transmitted to the cylinder block of the internal combustion engine 2, and the explosion stroke It is set to the timing after the explosion process starts a little before. Specifically, here, the crank angle is between BTDC30CA and ATDC60CA.

  For example, the normal fuel injection period (A) of the # 1 cylinder partially overlaps with the vibration detection period of the # 4 cylinder. Similarly, the normal injection period (A) of the # 4 cylinder partially overlaps with the vibration detection period of the # 1 cylinder. That is, in the # 4 cylinder and the # 1 cylinder, the vibration generation timing due to the drive of the fuel injection valve 6 and the vibration detection period of abnormal combustion overlap each other. The same relationship applies to the # 3 and # 2 cylinders.

  Here, in particular, vibration due to abnormal combustion generated in a cylinder located far from the knock sensor 12 such as the # 1 cylinder and the # 4 cylinder is not easily transmitted to the knock sensor 12. Therefore, when the operation region is in the abnormal combustion generation operation region, the injection period is retarded or advanced so that the drive noise of the fuel injection valve 6 does not affect the detection of abnormal combustion vibrations in the # 1 cylinder and # 4 cylinder. Adjust by turning the corner.

  Specifically, when the operating region of the internal combustion engine 2 is an abnormal combustion occurrence region, the injection periods of the # 4 cylinder and the # 1 cylinder, which overlap with the vibration detection periods of the # 1 cylinder and the # 4 cylinder in advance, It is retarded from the normal injection period (A) and set to the injection period (B) when there is a possibility of occurrence of abnormal combustion (hereinafter referred to as “abnormal injection period”).

  The abnormal-time injection period (b) is a period set within a range in which the injection timing can be set as indicated by the broken-line arrows in FIG. 2 and does not overlap with the vibration detection period of the # 1 cylinder or the # 4 cylinder. It's time. This can prevent the fuel injection valve 6 of the # 4 cylinder or # 1 cylinder from being driven during the vibration detection period in the # 1 cylinder or # 4 cylinder.

  FIG. 3 is a flowchart for illustrating a control routine executed by ECU 20 as the control device in the first embodiment of the present invention. In the routine of FIG. 3, it is first determined from the current operating condition of the internal combustion engine 2 whether or not it is currently in an abnormal combustion generation operation region, which is a region where abnormal combustion is likely to occur (S102). Here, whether or not the current operation state is an abnormal combustion occurrence operation region is whether or not the current operation state satisfies a preset condition, for example, whether a high load operation state continues. Based on the determination. Here, when it is not recognized that the engine is in the abnormal combustion occurrence operation region, the current process is terminated.

  On the other hand, if it is determined in step S102 that the region is in the abnormal combustion occurrence operation region, then, among the cylinders # 1 to # 4, the vibration detection period of one cylinder and the current from the fuel injection valve 6 of the other cylinder are detected. It is determined whether or not the injection period overlaps (S104). Here, if it is not recognized that the vibration detection period of one cylinder overlaps the injection period of the other cylinders, the current process ends.

  On the other hand, if it is found in step S104 that the vibration detection period of one cylinder and the injection period of the other cylinder overlap, then the injection periods of the # 1 and # 4 cylinders are the vibrations of the other cylinders. It is delayed until the abnormal injection period (b) after the end of the detection period and reset (S106). Thereafter, the current process ends.

  As described above, in the first embodiment, the abnormal combustion of the end cylinders (# 1, # 4) is performed in the abnormal combustion generation operation region where abnormal combustion is likely to occur due to the operation conditions of the internal combustion engine 2. It is possible to avoid mixing the drive noise of the fuel injection valves 6 of the other cylinders during the vibration detection period due to. Thereby, even in the cylinder at the end portion far from the knock sensor 12, it is possible to suppress the influence of other vibrations and more accurately determine the presence or absence of abnormal combustion.

  In the first embodiment, the case where only the injection period of the # 1 cylinder and the # 4 cylinder is retarded in the abnormal combustion generating operation region has been described. However, in the present invention, the cylinder for retarding the injection period is not limited to this. For example, in consideration of the installation position of the knock sensor 12, the injection period of another cylinder that overlaps with the vibration detection period of the cylinder located far enough to prevent the vibration caused by abnormal combustion from being transmitted may be adjusted. .

  Alternatively, when it is determined that the engine is in the abnormal combustion generation operation region regardless of the installation position of the knock sensor 12, the injection period of all the cylinders may be uniformly retarded. As a result, since it is possible to avoid the overlap of the injection periods of the other cylinders in each vibration detection period for all the cylinders, vibrations due to abnormal combustion can be detected more accurately.

  In the first embodiment, the case where the injection period is retarded so that the vibration detection period of one cylinder and the injection periods of the other cylinders do not completely overlap has been described. However, the present invention is not limited to this, and the ejection period may be reset so that the overlap between the vibration detection period of one cylinder and the injection period of the other cylinders is reduced.

  In the first embodiment, the “operation region determining means” of the present invention is realized by executing the process of step S102, and the “period determining means” is realized by executing the process of step S104. The “injection period adjusting means” is realized by executing the process of step S106.

Embodiment 2. FIG.
In the first embodiment, the case where the injection period from the fuel injection valve 6 is retarded within the range of the fuel injectable timing when the operation of the internal combustion engine 2 is in the abnormal combustion generation operation region has been described. However, for example, particularly in the case of eight cylinders, if an attempt is made to retard the injection period while avoiding the vibration detection period, the fuel injection may not be completed within the range of the fuel injectable period. The system according to the second embodiment of the present invention performs control corresponding to such a case.

  FIG. 4 is a schematic diagram for explaining an internal combustion engine to which the system of the second embodiment of the present invention is applied. The internal combustion engine 30 in FIG. 4 is installed in place of the internal combustion engine 2 in FIG. The internal combustion engine 30 includes two cylinder groups 32a and 32b. In each cylinder group 32a, four cylinders # 1, # 3, # 5, and # 7 are formed. Four cylinders # 2, # 4, # 6, and # 8 are formed in the cylinder group 32b. The ignition order of the internal combustion engine is # 1 → # 8 → # 4 → # 3 → # 6 → # 5 → # 7 → # 2.

  In the second embodiment, knock sensors 34a and 34b are provided for each of the cylinder groups 32a and 32b. Knock sensors 34a and 34b are respectively installed near the center position of the four cylinders of the cylinder block, that is, between the # 3 cylinder and the # 5 cylinder and between the # 4 cylinder and the # 6 cylinder. Accordingly, in the cylinder group 32a, the distance between the knock sensor 34a and the # 1 cylinder and # 7 cylinder is relatively long, and in the cylinder group 32b, the distance between the knock sensor 34b and the # 2 cylinder and # 8 cylinder is relatively long. It ’s far away.

  Although not shown, the internal combustion engine 30 has a port injection valve that is disposed in each intake port communicating with each cylinder and injects fuel into the intake port. In the internal combustion engine, fuel injection is performed by using both direct injection from the fuel injection valve 6 into each cylinder and port injection to each intake port.

  FIG. 5 is a diagram for describing control executed by the ECU 20 as the control device in the second embodiment. In FIG. 5, the cylinder numbers are shown in the leftmost column, and each row represents a stroke of one cycle in each cylinder. As shown in FIG. 5, the vibration detection period for detecting abnormal combustion is a period after ignition from slightly before the explosion stroke of each cylinder, and the crank angle is BTDC30CA to ABDC60CA.

  In the example shown in FIG. 5, the cylinder group 32a overlaps with the normal injection period (A) of the # 3 cylinder within the vibration detection period of the # 1 cylinder at the end of the cylinder group 32a when viewed from the cylinder groups 32a and 32b. The # 7 cylinder's vibration detection period overlaps the # 7 cylinder's injection period (i). Similarly, in the cylinder group 32b, the normal injection periods (i) of the # 4 cylinder, # 2 cylinder, and # 6 cylinder overlap the vibration detection periods of the # 2, # 6, and # 8 cylinders. .

  As described above, when abnormal combustion occurs in the cylinder (# 1, # 2, # 7, # 8) at the end far from the knock sensor 34a or 34b, vibration due to the combustion is transmitted to the knock sensors 34a, 34b. It is hard to be done. For this reason, if fuel injection in other cylinders is started during the vibration detection period, erroneous determination of abnormal combustion is likely to occur due to drive noise of the fuel injection valve 6.

  Therefore, in particular, during the vibration detection periods of the # 1, # 8, and # 2 cylinders (hereinafter referred to as “specific cylinders”) at the end, the # 3, # 6, and # 4 cylinders ( Hereinafter, the fuel injection period is controlled so that the injection periods of these “other cylinders” do not overlap. However, as in the first embodiment, even if an attempt is made to retard the fuel injection period, there is a large overlap on the retarded side between the vibration detection period and the injection timing settable period of other cylinders. It is difficult to set the injection period later.

  Therefore, in the second embodiment, the injection period of the other cylinders is advanced as much as possible within the range of the injection timing setting period, and is shortened to a timing that does not overlap the vibration detection period of the specific cylinder. In this case, the injection period is short and the required amount of fuel cannot be injected. For this reason, it is set as the structure which increases the ratio of port injection and compensates for the insufficient fuel.

  FIG. 6 is a flowchart for illustrating a control routine executed by the ECU as the control device in the second embodiment of the present invention. The routine in FIG. 6 is the same as the routine in FIG. 4 except that the processing in steps S202 to S208 is performed instead of S106 in FIG.

  First, in step S102, it is recognized from the current operating conditions that the region is in the abnormal combustion occurrence operation region, and in step S104, it is recognized that the injection period of direct injection from the fuel injection valve 6 overlaps the vibration detection period. Then, in step S202, it is determined whether or not the injection period can be set. This determination is made as to whether or not the injection period of the fuel injection valve 6 of the other cylinder can be adjusted so that the injection period of the other cylinder does not overlap the vibration detection period of one cylinder within the injection timing settable period. Determined.

  If it is determined in step S202 that the injection period can be set, then the injection periods of the # 3, # 6, and # 4 cylinders are adjusted to timings that can be set on the advance side or the retard side (step S202). S204).

  On the other hand, if it is not recognized in step S202 that the injection period can be set, the injection time and the start timing of the direct injection are next determined for the injection periods of # 3, # 6, and # 4 cylinders. It is adjusted (S206). That is, here, in the same cylinder group 32a or 32b, the injection periods of the # 3, # 6, and # 4 cylinders overlap with the vibration detection periods of the end cylinders # 1, # 8, and # 2. Accordingly, for the injection periods of # 3, # 6, and # 4 cylinders, the injection start timing is advanced as much as possible within the injection timing setting period, and vibrations of # 1, # 8, and # 2 cylinders are detected. It is shortened to a range that does not overlap the period, and adjusted to the abnormal combustion injection period (b).

  Next, the port injection ratio in the fuel injection of # 3, # 6, and # 4 cylinders is increased (S208). In this case, the increased port injection ratio is set so as to compensate for the shortage of fuel due to the reduction of the injection time by adjusting the direct injection period in step S206. Thereafter, the current process ends.

  As described above, according to the second embodiment, even when the timing of direct fuel injection cannot be adjusted by shifting the retarded side or when the injection period cannot be sufficiently secured, It is possible to prevent the cylinder vibration detection period from overlapping. Therefore, vibration due to abnormal combustion can be detected with higher accuracy, and erroneous determination can be avoided.

  In the second embodiment, the “adjustment determining means” of the present invention is realized by executing the process of step S202, and the “injection period shortening setting means” is executed by executing the process of step S206. By realizing and executing the processing of step S208, “insufficient fuel amount calculating means” and “port injection amount setting means” are realized.

  While the second embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the second embodiment, a case has been described in which control is performed so that the vibration detection period of a specific cylinder does not overlap with the injection periods of other cylinders. However, the present invention is not limited to this, and in the detection of abnormal combustion, the range where the drive noise can be tolerated is specified, and accordingly, the allowable range of overlap between the injection period and the vibration detection period is determined, The injection period may be adjusted so as to be within this allowable range.

  In the second embodiment, the case of eight cylinders has been described. However, in the present invention, the internal combustion engine is not limited to this. The control of the second embodiment can be applied to, for example, a four-cylinder internal combustion engine as in the first embodiment, and an internal combustion engine having another number of cylinders such as a six-cylinder or a twelve-cylinder internal combustion engine. It is also possible to apply to.

  Further, in the second embodiment, the case has been described in which adjustment is performed so that the injection period and the vibration detection period do not overlap with each other and a certain specific cylinder. However, the present invention is not limited to this. Due to the advance angle (or retard angle) of the injection period, the injection period of the other cylinders is one order before the related specific cylinder (in the case of a retard angle). May overlap with the vibration detection period of the next cylinder). In this case, the injection period of the other cylinders may be adjusted in relation to the related specific cylinder and the cylinder whose ignition sequence is one before (or after) the ignition sequence. However, according to the ignition order in the second embodiment, each of the injection periods of the other cylinders and the cylinders whose ignition timing is one before the specific cylinder related thereto are not in the same cylinder group. Therefore, the injection period can be adjusted only in relation to the specific cylinder related to the other cylinders.

  Further, in the second embodiment, the case has been described in which the short fuel amount is injected by the port injection when the injection period of the direct injection cannot be adjusted within the injection timing setting period. However, in the present invention, the adjustment of the injection period is not limited to this. For example, in the case of split injection of fuel, the rest period between the split injection period and the split injection period is adjusted to be longer by advancing or retarding the split injection periods of the other cylinders. To do. In addition, by overlapping the vibration detection period of the specific cylinder during the pause period, the overlap between the injection period of the other cylinders and the vibration detection period of the specific cylinder is reduced to an allowable range or does not overlap. You can also

  Conversely, by shortening the interval between split injections of the other cylinders and shortening the period from the start of injection from the fuel injection valve 6 to the completion of injection, there is no overlap with the vibration detection period of the specific cylinder, Or you may adjust so that it may decrease to an allowable range.

  In the second embodiment, the normal injection period (A) of the # 3, # 6, and # 4 cylinders (other cylinders) is the end cylinder # 1 in each of the cylinder groups 32a and 32b. Since it overlaps with the vibration detection period of the cylinder, # 8 cylinder, # 2 cylinder (specific cylinder), only when the direct injection period is adjusted or the port injection ratio is increased only for the injection period (b) of the other cylinders Explained. However, the present invention is not limited to this, and in the abnormal combustion generation operation region, the injection period from the fuel injection valve 6 overlaps with any one of the vibration detection periods of all the cylinders in the same cylinder group. For other cylinders, the injection period may be adjusted, or the port injection may be increased.

  For example, in the example of FIG. 5, the injection periods of the # 7 cylinder and # 2 cylinder overlap with the vibration detection periods of the # 3 cylinder and # 6 cylinder of the same cylinder group. Therefore, the normal injection periods (A) of the # 7 cylinder and the # 2 cylinder may be adjusted together with the # 3, # 6, and # 4 cylinders (other cylinders). Alternatively, in the abnormal combustion generation operation region, when the injection period of another cylinder overlaps with the vibration detection period of any cylinder, the injection period may be adjusted or shortened uniformly for all the cylinders. Good.

  Further, when knock sensor 34a or 34b is arranged at another position, not only the example of the second embodiment, but a cylinder whose detection accuracy is lowered due to the installation position of knock sensor 12 is specified cylinder. In the same cylinder group, the injection period of other cylinders that overlap the vibration detection period of the specific cylinder may be adjusted. This adjustment may be performed only between cylinders in the same cylinder group using the same knock sensor 12, or may be performed among all cylinders including those of other cylinder groups. May be.

  In the above embodiment, when referring to the number of each element, quantity, quantity, range, etc., the reference is made unless otherwise specified or the number is clearly specified in principle. The invention is not limited to the numbers. Further, the structure, method, and the like described in this embodiment are not necessarily essential to the present invention unless otherwise specified or clearly specified in principle.

2 Internal combustion engine 6 Fuel injection valve 12 Knock sensor 30 Internal combustion engine 32a, 32b Cylinder group 34a, 34b Knock sensor

Claims (8)

A fuel injection valve disposed in each of the plurality of cylinders of the internal combustion engine and injecting fuel directly into each of the plurality of cylinders;
A knock sensor that is installed in common among at least two of the plurality of cylinders and generates an output corresponding to vibration;
An internal combustion engine control device comprising:
Abnormal combustion detection means for detecting abnormal combustion in each of the plurality of cylinders according to an output of the knock sensor in a vibration detection period set for each of the plurality of cylinders;
An operation region determination means for determining whether or not the current operation region of the internal combustion engine is a region where abnormal combustion can occur;
Of the plurality of cylinders, when the operation region determination unit determines that the region is in a region where abnormal combustion can occur, the vibration detection period of one cylinder and the fuel injection valve in another cylinder Period determining means for determining whether or not the fuel injection period overlaps;
When it is determined that the vibration detection period of the one cylinder and the injection period of the other cylinder overlap, at least the injection period of the other cylinder overlaps with the vibration detection period of the one cylinder. Injection period adjusting means for adjusting to timing;
A control device for an internal combustion engine, comprising:   2. The control apparatus for an internal combustion engine according to claim 1, wherein the injection period adjusting means retards an injection period of the other cylinder. The internal combustion engine includes a port injection valve for injecting fuel into each intake port communicating with each of the plurality of cylinders,
Adjustment determination for determining whether or not the injection period and the vibration detection period of the one cylinder can be adjusted within an allowable range by retarding or advancing the injection period of the other cylinder Means,
Advance or retard the injection period of the other cylinder when it is determined that the overlap between the injection period of the other cylinder and the vibration detection period of the one cylinder cannot be adjusted to be within an allowable range. An injection period shortening setting means for shortening the injection period of the other cylinder in a range in which an overlap between the vibration detection period of the one cylinder and the injection period of the other cylinder can be allowed.
A deficient fuel amount calculating means for calculating a fuel amount deficient due to the shortening of the injection period when the injection period of the other cylinder is shortened by the injection period shortening setting means;
Port injection amount setting means for setting the fuel injection amount from the port injection valve by adding the insufficient fuel amount;
The control device for an internal combustion engine according to claim 1, further comprising: Adjustment determination for determining whether or not the injection period and the vibration detection period of the one cylinder can be adjusted within an allowable range by retarding or advancing the injection period of the other cylinder Means further comprising
The injection period consists of a divided injection period divided into two or more and a pause period between them.
The injection adjusting means includes
When it is determined that the overlap between the injection period of the other cylinder and the vibration detection period of the one cylinder cannot be adjusted to be within an allowable range, the pause period of the other cylinder is lengthened and the pause 2. The control apparatus for an internal combustion engine according to claim 1, wherein the injection period is adjusted so that the period overlaps at least a part of the vibration detection period of the one cylinder. Adjustment determination for determining whether or not the injection period and the vibration detection period of the one cylinder can be adjusted within an allowable range by retarding or advancing the injection period of the other cylinder Means further comprising
The injection period consists of a divided injection period divided into two or more and a pause period between them.
The injection adjusting means includes
When it is determined that adjustment cannot be made so that an overlap between the injection period of the other cylinder and the vibration detection period of the one cylinder falls within an allowable range, the injection period is reduced by shortening the pause period of the other cylinder. 2. The control device for an internal combustion engine according to claim 1, wherein the control period of the internal combustion engine according to claim 1 is adjusted such that the period is shortened and an overlap between a vibration detection period of the one cylinder and an injection period of the other cylinder falls within an allowable range.   6. The control device for an internal combustion engine according to claim 1, wherein the one cylinder is a cylinder disposed at a position farthest from the knock sensor. The injection period adjusting means is
When it is determined that the vibration detection period of the one cylinder and the injection period of the other cylinder overlap, the injection period for all of the plurality of cylinders is set as the vibration detection period of any of the plurality of cylinders. The control apparatus for an internal combustion engine according to any one of claims 1 to 5, wherein the control is performed at a timing at which the overlap with the engine becomes less. The internal combustion engine includes a plurality of cylinder groups each having a plurality of cylinders,
The knock sensor is installed for each cylinder group,
The control apparatus for an internal combustion engine according to any one of claims 1 to 7, wherein the one cylinder and the other cylinder are cylinders arranged in the same cylinder group.

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