JP2018105162A - Internal combustion engine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine control device capable of realizing a stable diffuse combustion by avoiding rapid combustion while assuring ignitability at the time of compression ignition.SOLUTION: ECU 16 includes an injection command part 24 for ordering both a main injection and a front-stage injection to an injector 15, and a penetration force determination part 23 for determining a penetration force of the front-stage injection in such a way that the front-stage injection range may become near an injection hole 17 of the injector 15 a compared with the main injection range. With this arrangement as above, it is restricted that the front-stage injection is diffused over an entire combustion chamber 11 and then mixture gas 29 containing radicals by low temperature oxidation reaction at the front-stage injection is locally generated at a location near the injection hole 17. Due to this fact, it is possible to supply radicals of high concentration to a location near the injection hole 17 for the main injection. Accordingly, it is possible to realize a stable diffusion combustion by avoiding a rapid combustion while assuring ignitability of compression ignition. With this arrangement as above, occurrence of vibration and increasing in NOx are restricted. In addition, since combustion at a place near a wall of the combustion chamber 11 is restricted, cooling loss is reduced.SELECTED DRAWING: Figure 5

Description

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

  2. Description of the Related Art Conventionally, an internal combustion engine that includes a fuel injection device that can inject fuel into a combustion chamber a plurality of times during one cycle and performs compression ignition is known. In Cited Document 1, after the first fuel injection for initial combustion speed control is performed in the intake stroke, an ignition trigger is applied by an ignition trigger means such as a spark plug, for example, and the torque control first in the subsequent compression stroke. 2 fuel injection is performed. The spray by the first fuel injection diffuses throughout the combustion chamber and becomes a uniform air-fuel mixture with the intake air, and then is activated by a compression and ignition trigger to generate radicals.

Japanese Patent No. 3911912

  In Cited Document 1, the spray by the first injection diffuses throughout the combustion chamber and becomes a uniform air-fuel mixture with intake air. For this reason, there is a risk of rapid combustion resulting from premixing and ignition at a location away from the nozzle hole of the fuel injection device. That is, it is impossible to realize clean diffusion combustion that does not burn at once, such that fine droplets evaporate and repeat self-ignition and combustion individually, and spread to adjacent droplets to generate a group of flames. Therefore, there are concerns about the occurrence of vibrations and an increase in NOx.

  The present invention was created in view of the above-mentioned points, and an object of the present invention is to control an internal combustion engine that can realize stable diffusion combustion while avoiding rapid combustion while ensuring ignitability of compression ignition. To provide an apparatus.

  The internal combustion engine control apparatus according to the present invention includes an injection command unit and an injection specification determination unit. The injection command unit commands the fuel injection device to execute main injection for main combustion that generates torque, and pre-stage injection that is injection before the main injection. The injection specification determining unit determines the penetration force of the spray by the front injection or the injection direction of the front injection so that the spray reach by the front injection is closer to the injection hole of the fuel injection device than the spray reach by the main injection. decide.

  With this configuration, it is possible to suppress the spray produced by the pre-stage injection from diffusing throughout the combustion chamber, and radicals generated by the low-temperature oxidation reaction of the spray are locally generated near the nozzle hole. Therefore, high concentration radicals can be supplied to the spray by the main injection at a location near the nozzle hole. Therefore, stable diffusion combustion can be realized by avoiding rapid combustion while securing the ignitability of compression ignition. Thereby, generation | occurrence | production of a vibration and the increase in NOx are suppressed. Further, since the combustion at the wall of the combustion chamber is suppressed, the cooling loss is reduced.

  Here, multistage injection in a diesel engine will be described. Even in a diesel engine, fuel injection may be performed twice. However, in the case of light oil, since it is highly reactive, it immediately undergoes a combustion reaction, and it is difficult to supply intermediate products such as radicals to the spray by the second injection. In a diesel engine, multistage injection is performed with the aim of increasing the in-cylinder temperature due to the combustion of the fuel of the first injection.

  Further, in the diesel engine, it is considered effective to make the injection location different between the first time and the second time in order to effectively use oxygen in the combustion chamber. For example, a swirl flow is used. On the other hand, in the present invention, in order to supply radicals to the spray by the main injection, it is effective to allow the spray by the main injection to pass through the spray range by the pre-stage injection.

  In this specification, “an internal combustion engine that performs compression ignition” refers to an internal combustion engine that does not include an ignition plug and performs only compression ignition, and an ignition plug that switches between a spark ignition mode and a compression ignition mode. And an internal combustion engine to be implemented.

It is a mimetic diagram explaining an internal combustion engine to which ECU by a 1st embodiment of the present invention is applied. It is a time chart which shows the injection quantity and injection timing of the injector of FIG. It is an expanded sectional view of the III section of Drawing 1, and is a figure showing typically the arrival range of the spray at the time of front stage injection. It is an expanded sectional view of the IV section of Drawing 1, and is a figure showing typically the arrival range of the spray at the time of main injection. It is a block diagram explaining the function part which ECU of FIG. 1 has. FIG. 3 is a time chart when a pre-stage injection ratio is set higher than that in FIG. 2. FIG. FIG. 3 is a time chart when the pre-injection ratio is set lower than that in FIG. It is a flowchart explaining the process by ECU of FIG. It is a schematic diagram explaining the internal combustion engine to which ECU by 2nd Embodiment of this invention was applied. FIG. 10 is a cross-sectional view of the internal combustion engine controlled by the ECU of FIG. 9, and schematically shows a spray reach range at the time of pre-injection. FIG. 10 is a cross-sectional view of the internal combustion engine controlled by the ECU of FIG. 9, schematically showing a spray reach range during main injection. It is a schematic diagram explaining the internal combustion engine to which ECU by 3rd Embodiment of this invention was applied. It is sectional drawing of the internal combustion engine which ECU of FIG. 12 controls, Comprising: It is a figure which shows typically the reach | attainment range of the spray at the time of front | former stage injection. It is sectional drawing of the internal combustion engine which ECU of FIG. 12 controls, Comprising: It is a figure which shows typically the reach | attainment range of the spray at the time of main injection. It is a block diagram explaining the function part which ECU by 4th Embodiment of this invention has. It is a time chart which shows the injection quantity and injection timing of the injector of FIG. It is a flowchart explaining the process by ECU of FIG. It is a block diagram explaining the function part which ECU by 5th Embodiment of this invention has. It is a block diagram explaining the function part which ECU by 6th Embodiment of this invention has. It is a time chart which shows the injection quantity and injection timing of the injector of FIG.

Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. In the embodiments, substantially the same components are denoted by the same reference numerals and description thereof is omitted.
[First Embodiment]
The ECU as the internal combustion engine control apparatus according to the first embodiment of the present invention controls the internal combustion engine 10 shown in FIG.

(Internal combustion engine)
An internal combustion engine 10 shown in FIG. 1 is an engine that uses, for example, gasoline as fuel and performs compression ignition. Compression ignition is an ignition method that utilizes the self-ignition of fuel injected into the compressed heated air in the combustion chamber 11. The combustion at this time is diffusion combustion in which fine droplets in the spray evaporate and repeat self-ignition and combustion individually, spread to adjacent droplets, and generate a flame as a group. Combustion injection is performed by a direct injection injector 15 that directly injects combustion into the combustion chamber 11 defined between the cylinder head 12 and the piston 14 in the cylinder 13.

  The injector 15 operates in accordance with a command from the ECU 16 and can inject fuel at least twice during one cycle through each stroke of intake, compression, expansion (combustion), and exhaust. The fuel injection by the injector 15 includes main injection for main combustion that generates torque, and pre-stage injection that is injection before the main injection. In this embodiment, as shown in FIG. 2, the main injection is performed once from the compression stroke to the expansion stroke, and the pre-injection is performed once in the compression stroke prior to the main injection. In the first embodiment, the upstream injection timing and the main injection timing are constant every cycle.

  The spray by the pre-stage injection undergoes a low-temperature oxidation reaction before the main injection, and generates radicals at a time overlapping with the main injection time. Radicals are highly reactive intermediate products, also called cold flames, and can improve the ignitability of fuel. This radical is present in high concentration only for a very limited time due to its chemical instability, for example, radicals generated from spray injected in the intake stroke may disappear at the end of the compression stroke. There is. Considering this point, the pre-injection timing in the first embodiment is set to the compression stroke so that the radical generation timing overlaps with the main injection timing.

In the first embodiment, as shown in FIGS. 3 and 4, the injector 15 has two types of injection holes 17 and 18. The injection hole 18 is an injection hole for injecting fuel when pre-injection is performed as shown in FIG. The injection hole 17 is an injection hole for injecting fuel when main injection is performed as shown in FIG. Both injection holes 17, 18 are directed toward the piston cavity 19 in the injection direction. The nozzle hole 18 has a smaller inner diameter (hereinafter referred to as a nozzle hole diameter) than the nozzle hole 17. The fact that the nozzle hole diameter is small means that the spray reach distance x expressed by the following equation (1) is shortened. In equation (1), ρf is the fuel density, ρa is the air density, _dn is the nozzle hole diameter, θ is the spray spread angle, and t is the injection time. W ₀ is the spray speed and is proportional to the square root of the injection pressure. For this reason, the penetration force of the spray by the pre-injection (hereinafter, the pre-stage spray) is smaller than the penetration force of the spray by the main injection (hereinafter, the main spray). An injector having two types of injection holes, one of which has a smaller injection hole diameter than the other, is disclosed in, for example, Japanese Patent Application Laid-Open No. 2013-119636, and thus a detailed description thereof is omitted.

(ECU function)
As shown in FIG. 5, the ECU 16 includes an information acquisition unit 21, an injection amount determination unit 22, a penetration force determination unit 23, and an injection command unit 24. The penetration force determining unit 23 constitutes an injection specification determining unit that determines an injection specification.

  The information acquisition unit 21 acquires the detection values of the temperature sensor 25 and the fuel property sensor 26 and the target load of the internal combustion engine 10 calculated by another control unit. The temperature sensor 25 is provided, for example, in the cylinder head 12 or the like, and detects the temperature of the combustion chamber 11 (hereinafter, combustion chamber temperature). The temperature sensor 25 is installed so that it does not protrude into the combustion chamber 11 in order to avoid interference with the spray or the amount of protrusion is very small. Thereby, it is suppressed that the temperature sensor 25 becomes high temperature and becomes an ignition source. The fuel property sensor 26 is provided in the middle of a fuel tank or a fuel supply path, for example, and detects properties such as the octane number of the fuel.

  The injection amount determination unit 22 first determines the total injection amount based on the target load. The total injection amount is the sum of the fuel injection amount of the main injection and the fuel injection amount of the pre-stage injection. Subsequently, the injection amount determination unit 22 determines the ratio of the injection amount of the pre-stage injection in the total injection quantity (hereinafter, the pre-stage injection ratio) based on the target load. Specifically, the injection amount determination unit 22 increases the pre-injection ratio as shown in FIG. 6 as the target load is lower (that is, the more difficult the compression ignition is), and the higher the target load is, the higher the target load is. As shown in FIG. 7, the pre-injection ratio is reduced (that is, compression ignition is easier). Thereby, when compression ignition is difficult, the amount of radicals generated by the low-temperature oxidation reaction of the pre-stage spray (hereinafter, radical amount) is relatively large as shown in FIG. Further, when compression ignition is easy, the radical amount is relatively small as shown in FIG. 7, and the main injection amount is relatively large.

  The penetration force determining unit 23 determines the penetration force of the front stage spray so that the reach range of the front stage spray (hereinafter, the front stage spray range) is closer to the nozzle hole 17 than the reach range of the main spray (hereinafter, the main spray range). decide. That is, the penetration force determining unit 23 controls the generation site of radicals by the previous stage spraying with the penetration force. Specifically, the penetrating force determination unit 23 determines that fuel is injected from the nozzle hole 18 having a nozzle hole diameter smaller than that of the nozzle hole 17 at the time of main injection at the time of preceding injection prior to main injection for main fuel. . That is, the nozzle hole 18 having a relatively small nozzle hole diameter is selected during the front-stage injection, and the nozzle hole 17 having a relatively large nozzle hole diameter is selected during the main injection. As a result, the front spray range Rp shown in FIG. 3 is closer to the nozzle hole 17 than the main spray range Rm shown in FIG.

  The injection command unit 24 includes a drive circuit for driving the injector 15 and commands the injector 15 to execute main injection and pre-stage injection with an injection amount and penetration force determined at a predetermined injection timing. .

(Processing by ECU)
The ECU 16 executes the process shown in FIG.
First, in step S <b> 1, the information acquisition unit 21 acquires the combustion chamber temperature, the fuel octane number, and the target load of the internal combustion engine 10.

  In step S2 after step S1, the injection amount determination unit 22 determines the total injection amount and the upstream injection ratio based on the target load. The lower the target load, the larger the upstream injection ratio is set, and the higher the target load, the smaller the upstream injection ratio.

  In step S3 after step S2, the penetration force determining unit 23 has an injection hole diameter larger than that of the injection hole 17 at the time of main injection so that the front spray range is closer to the injection hole 17 than the main spray range. It is decided to inject fuel from the small nozzle hole 18.

In step S4 after step S3, the injection command unit 24 performs main injection and pre-stage injection at a predetermined injection timing with the injection amount determined in step S2 and the penetration force determined in step S3. To the injector 15.
After step S4, the process exits the routine of FIG.

(effect)
As described above, in the first embodiment, the ECU 16 instructs the injector 15 to execute the main injection and the pre-stage injection, and the injection hole 17 of the injector 15 in which the pre-stage spray range is compared with the main spray range. A penetrating force determining unit 23 that determines the penetrating force of the pre-stage spray so as to be closer is provided.

  With this configuration, it is possible to suppress the pre-stage spray from diffusing throughout the combustion chamber 11, and as shown in FIG. 4, the air-fuel mixture 29 containing radicals due to the low-temperature oxidation reaction of the pre-stage spray is located near the nozzle hole 17. It occurs locally. Therefore, high concentration radicals can be supplied to the main spray at a location near the nozzle hole 17. Therefore, stable diffusion combustion can be realized by avoiding rapid combustion while securing the ignitability of compression ignition. Thereby, generation | occurrence | production of a vibration and the increase in NOx are suppressed. Further, since the combustion at the wall of the combustion chamber 11 is suppressed, the cooling loss is reduced.

  Here, radicals are present in a high concentration only for a very limited time due to their chemical instability, for example, radicals generated from spray injected in the intake stroke disappear at the end of the compression stroke. there is a possibility. Further, the spray injected in the intake stroke is diffused throughout the combustion chamber 11 by the flow of intake air. On the other hand, in the first embodiment, since the pre-stage injection is performed in the compression stroke, the radical generation time can be set so as to overlap with the main injection time, and the radical is locally arranged in the vicinity of the nozzle hole 17. can do.

Moreover, in 1st Embodiment, the penetration diameter of the front stage spray is made into the penetration force of the main spray by making the nozzle hole diameter of the injection hole 18 at the time of front stage injection smaller than the nozzle hole diameter of the nozzle hole 17 at the time of main injection. Compared to the main spray range, the front spray range is made closer to the injection hole 17 of the injector 15.
Thereby, radicals due to the low-temperature oxidation reaction of the pre-stage spray are locally generated near the nozzle hole 17.

Moreover, in 1st Embodiment, the information acquisition part 21 which acquires the information regarding the load of the internal combustion engine 10 is provided. The injection amount determination unit 22 increases the upstream injection ratio as the load on the internal combustion engine 10 is low, and decreases the upstream injection ratio as the load on the internal combustion engine 10 is high.
As a result, the amount of radicals is relatively large under conditions where compression ignition is difficult, so that the ignitability is improved. In addition, the radical amount is relatively small and the main injection amount is relatively large under the condition where compression ignition is easy, so that the isovolume is improved and the thermal efficiency is enhanced.

[Second Embodiment]
In the second embodiment of the present invention, the penetration force determining unit 32 of the ECU 31 shown in FIG. 9 determines the penetration force of the front stage spray so that the front stage spray range is closer to the nozzle hole 17 of the injector 15 than the main spray range. To do. That is, the penetrating force determining unit 32 determines that the fuel is injected with the nozzle hole diameter and the injection pressure being smaller at the time of the pre-injection prior to the main injection for the main fuel than at the time of the main injection.

The diameter of the nozzle hole 18 at the time of the previous injection is made smaller than the diameter of the nozzle hole 17 at the time of the main injection, and the injection pressure at the time of the previous injection is made smaller than the injection pressure at the time of the main injection. The fact that the nozzle hole diameter and the injection pressure are small means that the spray reach distance x expressed by the equation (1) is shortened. In equation (1), W ₀ is the spray speed and is proportional to the square root of the injection pressure. Thereby, the penetration force of the front stage spray is smaller than that of the main spray, and the front stage spray range Rp shown in FIG. 10 is closer to the injection hole 17 of the injector 15 than the main spray range Rm shown in FIG. An injector having a variable injection pressure is disclosed in, for example, Japanese Translation of PCT International Publication No. 2009-545701, and thus a detailed description thereof is omitted.

Thus, even if the injection pressure at the time of the front stage injection is made smaller than the injection pressure at the time of the main injection, the front stage spray range can be closer to the injection hole 17 of the injector 15 than the main spray range. Therefore, as in the first embodiment, it is possible to achieve stable diffusion combustion by avoiding rapid combustion while ensuring the ignitability of compression ignition.
Further, by reducing both the nozzle hole diameter and the injection pressure at the time of the front injection, the front spray range can be made closer to the nozzle hole 17 than when only one of them is reduced.

[Third Embodiment]
In the third embodiment of the present invention, the penetration force determination unit 42 of the ECU 41 shown in FIG. 12 determines the injection direction of the front spray so that the front spray range is closer to the injection hole 44 of the injector 43 than the main spray range. To do. That is, the penetrating force determination unit 42 determines that the fuel is injected with the injection direction closer to the partition wall of the combustion chamber 11 in the pre-stage injection prior to the main injection for the main fuel as compared with the main injection.

As shown in FIGS. 13 and 14, the injector 43 has two types of injection holes 17 and 44.
As shown in FIG. 14, the injection direction of the injection hole 17 at the time of main injection is directed to the piston cavity 19. On the other hand, as shown in FIG. 13, the injection direction of the injection hole 44 at the time of the front injection is directed to the upper surface 45 of the piston 14 that is one of the partition walls of the combustion chamber 11. Since the injection direction at the time of the front injection is directed closer to the partition wall of the combustion chamber 11 than the injection direction at the time of the main injection, the front spray range Rp shown in FIG. 13 is an injector compared to the main spray range Rm shown in FIG. 43 near the nozzle hole 17. An injector that includes two types of injection holes and makes one injection direction different from the other injection direction is disclosed in, for example, Japanese Patent Application Laid-Open No. 2013-198136, and thus detailed description thereof is omitted.

  Thus, even if the injection direction at the time of the front stage injection is directed closer to the partition wall of the combustion chamber 11 than at the time of the main injection, the front stage spray range can be closer to the injection hole 17 of the injector 43 than the main spray range. . Therefore, as in the first embodiment, it is possible to achieve stable diffusion combustion by avoiding rapid combustion while ensuring the ignitability of compression ignition.

[Fourth Embodiment]
In the fourth embodiment of the present invention, the injection timing determination unit 52 of the ECU 51 shown in FIG. 15 performs the combustion chamber temperature and fuel control so that the generation timing of radicals due to the low-temperature oxidation reaction of the pre-stage spray overlaps the injection timing of the main injection. The injection timing of the pre-stage injection is determined based on the octane number. That is, the injection timing determination unit 52 controls the radical generation timing by the injection timing of the pre-stage injection.

  Specifically, as shown in FIG. 16, the injection timing determination unit 52 retards the injection timing of the pre-injection as the combustion chamber temperature is higher (that is, the low-temperature oxidation reaction is more likely to proceed) to determine the combustion chamber temperature. Is lower (that is, the lower the temperature oxidation reaction is, the more difficult the advancement is). Further, the injection timing determination unit 52 retards the injection timing of the preceding injection as the octane number of the fuel is lower (that is, the low-temperature oxidation reaction is more likely to proceed), and as the octane number of the fuel is higher (that is, the low-temperature oxidation reaction is performed). Advancing the injection timing of the preceding injection)

The ECU 51 executes the process shown in FIG. Steps S11, S12, S14, and S15 have the same contents as steps S1 to S4 in FIG. 8 of the first embodiment.
In step S13 after step 12, the injection timing determination unit 52 performs the pre-injection based on the combustion chamber temperature and the octane number of the fuel so that the generation timing of radicals by the low-temperature oxidation reaction of the pre-stage spray overlaps the injection timing of the main injection. Determine the injection timing.

  In this way, by changing the injection timing of the pre-stage injection based on the combustion chamber temperature and the octane number of the fuel, the radical generation timing can be overlapped with the main injection timing. Therefore, high concentration radicals can be supplied to the main spray at a location near the nozzle hole 17. Therefore, as in the first embodiment, it is possible to achieve stable diffusion combustion by avoiding rapid combustion while ensuring the ignitability of compression ignition.

[Fifth Embodiment]
In the fifth embodiment of the present invention, the penetrating force determining unit 62 of the ECU 61 shown in FIG. 18 performs the injection in addition to reducing the injection pressure at the time of the pre-stage injection as compared with the time of the main injection as in the third embodiment. The injection pressure at the preceding injection is increased or decreased according to the advance / delay angle of the injection timing of the preceding injection by the timing determining unit 52. Specifically, the penetration force determining unit 62 decreases the injection pressure at the front stage injection to reduce the penetration power at the front stage spray as the injection timing of the front stage injection is advanced, and retards the injection timing of the front stage injection. The injection pressure at the front stage injection is increased to increase the penetration force of the front stage spray.

  For example, when the injection timing is advanced, it takes a long time for the air-fuel mixture to diffuse, making it difficult to place the radicals locally near the nozzle holes. On the other hand, in the fifth embodiment, the diffusion force of the air-fuel mixture is suppressed by reducing the penetration force of the front stage spray as the injection timing of the front stage injection is advanced.

[Sixth Embodiment]
In the sixth embodiment of the present invention, the injection amount determination unit 72 of the ECU 71 shown in FIG. 19 sets the front injection ratio to the combustion chamber so that the generation timing of radicals due to the low temperature oxidation reaction of the front spray overlaps the injection timing of the main injection. Determine based on temperature and octane number. That is, the injection amount determination unit 72 controls the radical generation timing based on the pre-injection ratio of the pre-injection.

  Specifically, as shown in FIG. 20, the injection amount determination unit 72 decreases the pre-injection ratio as the combustion chamber temperature is higher (that is, as the low-temperature oxidation reaction proceeds more easily), and as the combustion chamber temperature is lower. The pre-injection ratio is increased (that is, the low-temperature oxidation reaction is difficult to proceed). Further, the injection amount determination unit 72 decreases the injection ratio as the octane number of the fuel is low (that is, the low-temperature oxidation reaction is likely to proceed), and as the fuel octane number is high (that is, the low-temperature oxidation reaction is difficult to proceed). Increase the front injection ratio.

  Thus, by changing the pre-injection ratio based on the combustion chamber temperature and the octane number of the fuel, more radicals can be generated at the injection timing of the main injection. Therefore, high concentration radicals can be supplied to the main spray at a location near the nozzle hole 17. Therefore, as in the first embodiment, it is possible to achieve stable diffusion combustion by avoiding rapid combustion while ensuring the ignitability of compression ignition.

  The low temperature oxidation reaction rate is a function of the ambient temperature, the equivalence ratio, and the octane number. The ECU 71 of the sixth embodiment sequentially calculates the low-temperature oxidation reaction rate, and controls the injection timing and the injection amount of the pre-stage injection so that the radical concentration becomes the highest at the main injection timing.

[Other Embodiments]
In other embodiments of the present invention, the pre-injection may be performed more than once. The main injection may be performed twice or more.
In another embodiment of the present invention, for example, alcohol fuel or gas fuel may be used as fuel other than gasoline.

  In another embodiment of the present invention, the ECU includes an ignition plug and is used to ensure the ignitability in the compression ignition mode in an internal combustion engine that is switched between the spark ignition mode and the compression ignition mode. Good. In such a form, the octane number of the fuel may be estimated based on the ignition timing and the in-cylinder pressure in the spark ignition mode. In the spark ignition mode, generally, in the case of combustion that tends to ignite (low octane number), control for delaying the ignition timing is performed to avoid knocking. The octane number of combustion is estimated from information obtained by such control.

  In another embodiment of the present invention, the temperature in the combustion chamber may be estimated based on the in-cylinder pressure detected by the in-cylinder pressure sensor, or may be estimated based on the temperature of the cooling water detected by the cooling water temperature sensor. . By measuring the cooling water temperature, for example, it can be predicted that the temperature in the combustion chamber is unlikely to rise during cold weather.

In other embodiment of this invention, 2nd Embodiment and 3rd Embodiment may be combined and implemented. That is, the injection pressure at the time of preceding injection may be made smaller than that at the time of main injection, and the injection direction at the time of preceding injection may be directed closer to the partition wall of the combustion chamber than at the time of main injection.
In another embodiment of the present invention, the injection hole diameter may not be changed between the front injection and the main injection, and the injection pressure during the front injection may be made smaller than that during the main injection.
The present invention is not limited to the embodiments described above, and can be implemented in various forms without departing from the spirit of the invention.

DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine 11 ... Combustion chamber 15 ... Fuel-injection apparatus 16 ... ECU (internal combustion engine control apparatus)
17 ... Injection hole 23, 32, 42, 62 ... Injection specification determining part 24 ... Injection command part Rp ... Pre-stage spray reach range Rm ... Main spray reach range

Claims (13)

A device for controlling an internal combustion engine (10) that includes a fuel injection device (15) capable of injecting fuel into a combustion chamber (11) a plurality of times during one cycle, and that performs compression ignition,
An injection command section (24) for instructing the fuel injection device to execute main injection for generating main torque for main combustion, and pre-injection that is injection before the main injection;
The penetration force of the spray by the preceding stage injection so that the reach range (Rp) of the spray by the preceding stage injection is closer to the injection hole (17) of the fuel injection device than the reach range (Rm) of the spray by the main injection. Or an injection specification determining unit (23, 32, 42, 62) for determining the injection direction of the preceding injection;
An internal combustion engine control device.   The internal combustion engine control device according to claim 1, wherein the pre-stage injection is performed in a compression stroke.   The injection specification determining unit (23, 32, 62) reduces the penetration force of the spray by the preceding injection by reducing one or both of the injection pressure and the nozzle hole diameter at the preceding injection as compared with the main injection. The fuel spray device according to claim 1 or 2, wherein the spray penetration force by the main injection is made smaller than the spray injection force by the main injection, and the spray reach by the main injection is closer to the nozzle hole of the fuel injection device than the spray reach by the main injection. The internal combustion engine control apparatus described.   The injection specification determination unit (42) directs the injection direction at the time of the preceding injection toward the partition wall (45) of the combustion chamber as compared with the time of the main injection, thereby setting the reach range of the spray by the preceding injection. The internal combustion engine control device according to any one of claims 1 to 3, wherein the internal combustion engine control device is closer to a nozzle hole of the fuel injection device than a spray reach range by main injection. An information acquisition unit (21) for acquiring information on the state quantity and fuel properties of the combustion chamber;
An injection timing determination unit (52) that determines the injection timing of the preceding injection based on the state quantity or the fuel property so that the generation timing of radicals by the low temperature oxidation reaction of the spray by the upstream injection overlaps the injection timing of the main injection. )When,
The internal combustion engine control device according to any one of claims 1 to 4, further comprising:   The injection timing determining unit retards the injection timing of the preceding injection as the temperature in the combustion chamber as the state quantity is higher, and advances the injection timing of the preceding injection as the temperature in the combustion chamber is lower. Item 6. The internal combustion engine control device according to Item 5.   The injection timing determination unit retards the injection timing of the preceding injection as the octane number of the fuel as the fuel property is lower, and advances the injection timing of the preceding injection as the octane number of the fuel is higher. An internal combustion engine control device according to claim 1.   The injection specification determining unit (62) reduces the penetration force of the spray by the preceding injection as the injection timing of the preceding injection is advanced, and performs the preceding injection as the injection timing of the preceding injection is retarded. The internal combustion engine control device according to any one of claims 5 to 7, wherein the penetration force of the spray is increased.   The injection specification determining unit (42) causes the injection direction at the preceding injection to be closer to the partition wall of the combustion chamber as the injection timing of the preceding injection is advanced, and the injection timing of the preceding injection is retarded. The internal combustion engine control device according to any one of claims 5 to 8, wherein an injection direction at the time of the preceding stage injection is separated from a partition wall of the combustion chamber. In the case where the sum of the injection amount of the preceding injection and the injection amount of the main injection is referred to as a total injection amount, and the proportion of the injection amount of the preceding injection in the total injection amount is referred to as a pre-injection proportion,
An information acquisition unit for acquiring information on the load of the internal combustion engine;
An injection amount determination unit (22) that increases the front injection ratio as the load on the internal combustion engine is lower, and decreases the front injection ratio as the load on the internal combustion engine is higher;
The internal combustion engine control device according to any one of claims 1 to 9, further comprising: In the case where the sum of the injection amount of the preceding injection and the injection amount of the main injection is referred to as a total injection amount, and the proportion of the injection amount of the preceding injection in the total injection amount is referred to as a pre-injection proportion,
An information acquisition unit for acquiring information on the state quantity and fuel properties of the combustion chamber;
An injection amount determination unit (72) for determining the pre-injection ratio based on the state quantity or the fuel property so that the generation timing of radicals due to the low-temperature oxidation reaction of the spray by the pre-injection overlaps the injection timing of the main injection; ,
The internal combustion engine control device according to any one of claims 1 to 9, further comprising:   The said injection specification determination part (72) makes the said front | former stage injection ratio small, so that the temperature in the said combustion chamber as said state quantity is high, and makes the said front stage injection ratio large, so that the temperature in the said combustion chamber is low. The internal combustion engine control apparatus described.   The said injection specification determination part (72) makes the said front | former stage injection ratio small, so that the octane number of the fuel as said fuel property is low, and makes the said front stage injection ratio large, so that the octane number of fuel is high. Internal combustion engine control device.

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