JP2006052686A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely suppress the knocking in an internal combustion engine in which gasoline is mainly used, in a control device of the internal combustion engine. <P>SOLUTION: A gasoline injection valve 30 is installed to directly inject gasoline into a cylinder. A hydrogen injection valve 38 is installed to inject hydrogen gas into an intake passage 18. An ignition plug 28 is installed to ignite an air-fuel mixture of hydrogen and air fed into the cylinder by the hydrogen injection valve 38. Gasoline is fed into the cylinder by the gasoline injection valve 30 almost at the same time as the hydrogen ignition by the ignition plug 28 or at the timing delayed from the ignition. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly to a control device for a spark ignition internal combustion engine that uses gasoline as a main fuel and uses hydrogen gas for combustion.

  Conventionally, for example, Japanese Patent Application Laid-Open No. 2004-116398 discloses a spark ignition internal combustion engine that uses gasoline and hydrogen as fuel. In this internal combustion engine, hydrogen is injected into the intake passage as an auxiliary fuel, and gasoline is injected into the cylinder as a main fuel. In this internal combustion engine, an air-fuel mixture of fuel (gasoline and hydrogen) and air supplied into the cylinder is ignited by an ignition plug, and the flame propagates to the unburned air-fuel mixture existing in the cylinder, thereby causing combustion. Done.

JP 2004-116398 A JP-A-6-235329 JP-A-7-63128

  As described above, in the conventional spark ignition internal combustion engine, combustion by flame propagation is realized using gasoline as a main fuel. According to the conventional engine, the flame propagation speed is improved by adding hydrogen, thereby making it difficult to cause knocking. However, in the method of combusting a mixture of gasoline and air by flame propagation as in the above-mentioned conventional engine, since there is an unburned mixture in front of the flame surface propagating in the cylinder, knocking is completely prevented. It cannot be suppressed.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a control device capable of reliably suppressing knocking in an internal combustion engine using gasoline as a main fuel.

In order to achieve the above object, a first invention is a control device for an internal combustion engine comprising a gasoline injection valve for directly injecting gasoline into a cylinder,
High-temperature and high-pressure field forming means for forming a high-temperature and high-pressure field capable of gasoline self-ignition in a cylinder;
Gasoline supply means for supplying gasoline into the cylinder at a predetermined timing during a period when the inside of the cylinder is the high temperature and high pressure field by the high temperature and high pressure field forming means,
The high temperature and high pressure field forming means includes a combustible gas supply means for supplying a combustible gas into the cylinder, and an ignition plug for igniting the combustible gas supplied into the cylinder.

  The second invention is characterized in that, in the first invention, the combustible gas is hydrogen gas.

  According to a third aspect, in the second aspect, the predetermined timing is substantially the same as or delayed from the ignition of hydrogen gas by the spark plug.

  The fourth invention is characterized in that, in the second or third invention, the combustible gas supply means supplies the hydrogen gas so that the hydrogen gas mixture is uniformly formed in the cylinder.

  According to a fifth invention, in the second or third invention, the combustible gas supply means supplies hydrogen gas so that a high-concentration hydrogen mixture layer is formed in the vicinity of the spark plug. And

  In addition, a sixth invention is characterized in that in any one of the second to fifth inventions, a supercharger for supplying compressed air into the cylinder is provided.

In addition, a seventh invention includes a combustion method selection means for selecting a combustion method according to the operating state of the internal combustion engine in any of the second to sixth inventions,
The combustion mode selection means selects the first combustion mode that realizes combustion using the gasoline supply means in an area where knocking is a concern, and in other areas, only gasoline is used as fuel and gasoline and air are used. It is possible to select a second combustion method that realizes combustion by directly igniting the air-fuel mixture with the spark plug.

  According to the first aspect of the present invention, a high-temperature and high-pressure field capable of self-ignition of gasoline is formed in the cylinder by igniting the combustible gas supplied in the cylinder with the spark plug. Then, by supplying gasoline into a cylinder that is a high-temperature and high-pressure field capable of self-ignition of gasoline, diffusion combustion using gasoline as fuel is realized. According to such a combustion method, unlike a normal gasoline internal combustion engine in which combustion is performed by igniting a gasoline mixture, combustion is possible without depending on flame propagation. The fuel mixture cannot be compressed. Therefore, according to the present invention, knocking can be reliably suppressed in an internal combustion engine using gasoline as the main fuel.

  According to the second invention, by using hydrogen gas having good ignitability and a sufficiently high flame propagation speed as the combustible gas, it becomes possible to perform rapid combustion under a high excess air ratio, and oxygen A good high temperature and high pressure field with a large remaining amount can be instantly formed.

  According to the third aspect of the invention, gasoline can be supplied into the cylinder during a period in which the cylinder is in a high temperature and high pressure field.

  According to the fourth invention, the hydrogen gas is uniformly supplied into the cylinder, so that a good high-temperature and high-pressure field is formed in the entire cylinder. For this reason, according to the present invention, stable gasoline combustion can be realized.

  According to the fifth aspect of the present invention, combustion can be performed under a sufficiently high air excess rate by stratified combustion of hydrogen gas. For this reason, according to the present invention, oxygen remaining in the cylinder at the time of gasoline combustion can be used effectively, and at the same time, the amount of hydrogen used can be saved.

  According to the sixth invention, supercharging can be performed without worrying about the occurrence of knocking, and a desired high torque can be easily obtained as compared with a normal gasoline engine.

  According to the seventh aspect, the total amount of hydrogen used can be saved by not using hydrogen gas in at least a part of the region (for example, the normal region) other than the region where knocking is a concern.

Embodiment 1 FIG.
FIG. 1 is a diagram for explaining a configuration of a spark ignition type internal combustion engine 10 according to a first embodiment of the present invention. A piston 12 that reciprocates inside the cylinder of the internal combustion engine 10 is provided. Further, the internal combustion engine 10 includes a cylinder head 14. A combustion chamber 16 is formed between the piston 12 and the cylinder head 14. An intake passage 18 and an exhaust passage 20 communicate with the combustion chamber 16. An intake valve 22 and an exhaust valve 24 are disposed in the intake passage 18 and the exhaust passage 20, respectively. A throttle valve 26 is provided in the intake passage 18. The throttle valve 26 is an electronically controlled throttle valve that can control the throttle opening independently of the accelerator opening.

  A spark plug 28 is attached to the cylinder head 14 so as to protrude into the combustion chamber 16 from the top of the combustion chamber 16. The cylinder head 14 is provided with a gasoline injection valve 30 that injects gasoline into the cylinder. A gasoline tank 34 communicates with the gasoline injection valve 30 through a gasoline supply pipe 32. The gasoline supply pipe 32 includes a pump 36 between the gasoline injection valve 30 and the gasoline tank 34. The pump 36 can supply gasoline to the gasoline injection valve 30 at a predetermined pressure. For this reason, the gasoline injection valve 30 is able to inject a quantity of gasoline into the cylinder according to the opening time by opening the valve in response to a drive signal supplied from the outside.

  The intake passage 18 is provided with a hydrogen injection valve 38 for injecting hydrogen gas into the port. The system of this embodiment includes a hydrogen tank 40 for storing hydrogen in a gaseous state at a high pressure. A hydrogen supply pipe 42 communicates with the hydrogen tank 40. The hydrogen supply pipe 42 communicates with the hydrogen injection valve 38. A regulator 44 is installed in the hydrogen supply pipe 42 between the hydrogen tank 40 and the hydrogen injection valve 38. According to such a configuration, hydrogen is supplied to the hydrogen injection valve 38 at a predetermined pressure reduced by the regulator 44. For this reason, the hydrogen injection valve 38 opens the valve in response to a driving signal supplied from the outside, and thereby can inject an amount of hydrogen into the intake passage 18 according to the valve opening time.

In addition, a hydrogen fuel pressure sensor 46 is incorporated in the hydrogen supply pipe 42 between the regulator 44 and the hydrogen injection valve 38. The hydrogen fuel pressure sensor 46 is a sensor that emits an output corresponding to the pressure of the hydrogen gas supplied to the hydrogen injector 38. The hydrogen supply pipe 42 further incorporates a hydrogen temperature sensor 48 between the hydrogen fuel pressure sensor 46 and the hydrogen injection valve 38. The hydrogen temperature sensor 48 is a sensor that emits an output corresponding to the temperature of the hydrogen gas supplied to the hydrogen injector 38. Compared with gasoline, which is a liquid, the density of hydrogen, which is a gas, varies greatly depending on pressure and temperature. Accordingly, when the hydrogen supply amount is controlled by the hydrogen injection period τ _H , it is necessary to measure the hydrogen fuel pressure and temperature. According to the configuration of the present embodiment, it is possible to accurately control the hydrogen supply amount to a desired value by correcting the hydrogen injection period τ _H according to the hydrogen pressure and temperature.

  The system of this embodiment includes an ECU 50. In addition to the hydrogen fuel pressure sensor 46 and the hydrogen temperature sensor 48 described above, the ECU 50 includes an accelerator position sensor 52, various engine speeds (not shown) for detecting the operating state of the internal combustion engine 10 and the like. Sensor is connected. The ECU 50 is connected to devices such as the ignition plug 28, the gasoline injection valve 30, the pump 36, and the hydrogen injection valve 38 described above. The ECU 50 can appropriately drive the various devices described above by performing predetermined processing based on the sensor outputs.

Next, the combustion technique used in this embodiment will be described with reference to FIGS.
FIG. 2 is a timing chart showing an example of setting of the hydrogen gas injection timing and ignition timing and gasoline injection timing used in the system of the present embodiment. In FIG. 2, the horizontal axis corresponds to the crank angle, and the waveform shown in FIG. 2 shows the waveform of the in-cylinder pressure of the internal combustion engine 10 in a predetermined operating state.

  As shown in FIG. 2, the hydrogen gas injection timing is set during the intake stroke or during the previous exhaust stroke so that the injection is completed by the end of the intake stroke. In the system of the present embodiment, the mixture of hydrogen gas and air supplied into the cylinder during the intake stroke is ignited by the spark plug 28, and the ignition timing for this is set to a predetermined level before compression top dead center. It is set at the time of arrival of the crank angle. Since the flame propagation speed of hydrogen gas is extremely high, the combustion of hydrogen gas is completed in a short period of time as shown in FIG. 2 with a “hydrogen mixture ignition period”. More specifically, the gasoline injection timing is set to a predetermined timing during the period in which the high-temperature and high-pressure field is formed in the cylinder by the combustion of hydrogen gas, more specifically, almost at the same time as the end of the hydrogen mixture ignition period. Is set. Further, these hydrogen ignition timing and gasoline injection timing are set at appropriate timings such that the in-cylinder pressure becomes maximum near the compression top dead center.

Next, a series of operations realized based on the setting of the timing chart shown in FIG. 2 will be described in detail with reference to FIG.
First, as shown in FIG. 3A, hydrogen gas is injected into the intake passage 18 by the hydrogen injection valve 38 during the intake stroke. Since hydrogen has good ignitability, lean burn combustion is possible at an excess air ratio λ (approximately λ> 3) compared to gasoline. For this reason, in this embodiment, hydrogen gas is supplied by the hydrogen injection valve 38 so that the above high air excess ratio is realized within a range in which no misfire occurs. In this way, hydrogen can be burned even in a fairly lean state, so that it is possible to secure enough air for gasoline combustion after hydrogen combustion, thereby enabling subsequent gasoline combustion. Yes.

  Next, when the compression stroke is started, as shown in FIG. 3B, the mixture of hydrogen gas and intake air that is uniformly sucked into the cylinder at a predetermined excess air ratio is compressed. Next, as shown in FIG. 3C, the hydrogen mixture is ignited by the spark plug 28 at a predetermined ignition timing during the compression stroke. As a result, when hydrogen gas burns, the in-cylinder pressure and the in-cylinder temperature rapidly increase, and a high-temperature and high-pressure field capable of gasoline self-ignition is formed in the cylinder. Next, as shown in FIG. 3D, when the gasoline is directly injected into the cylinder under such a high temperature and high pressure condition, the gasoline is heated to the auto-ignition temperature or higher. At this time, as shown in FIG. 3 (E), the gasoline injected into the cylinder is vaporized and diffused, so that a combustible air-fuel mixture layer is formed between the gasoline and the in-cylinder air. Combustion progresses explosively from one or several places. And while gasoline is being injected into the cylinder, the gasoline introduces oxygen around the spray and advances combustion one after another. That is, according to the combustion method of the present embodiment, diffusion combustion using gasoline as fuel is realized by directly injecting gasoline into a cylinder in which a high-temperature and high-pressure field is formed by combustion of hydrogen gas.

  Combustion in a normal spark-ignition internal combustion engine that uses gasoline as a fuel ignites a mixture of gasoline and air that has been mixed in advance, or a mixture that has been stratified so that the concentration near the spark plug is high. It is performed by igniting with the spark of the plug and the flame propagating to the unburned mixture present in the cylinder. In a normal spark ignition type internal combustion engine having such a combustion system, the unburned mixture at the end of the combustion chamber 16 existing in front of the flame surface propagating in the combustion chamber 16 is compressed in a low rotation high load region or the like. Thus, the phenomenon of self-ignition at a high temperature, that is, knocking may occur. Therefore, in an area where the occurrence of knocking is a concern, the ignition timing cannot be advanced to an appropriate timing, and thus high-efficiency operation becomes difficult.

  On the other hand, according to the above combustion method used in the system of the present embodiment, gasoline having a higher octane number than that of light oil, that is, self-ignition hardly occurs (in other words, difficult to diffuse combustion). Using this as a fuel, diffusion combustion can be realized. That is, since combustion without causing flame propagation itself is possible, the unburned mixture in the combustion chamber 16 cannot be compressed. Therefore, according to the system of the present embodiment, it is possible to realize an operation that does not cause knocking in the spark ignition internal combustion engine 10 that uses gasoline as the main fuel.

  FIG. 4 is a flowchart of a routine executed by the ECU 50 in order to realize the above functions in the first embodiment. In addition, this routine shall be periodically performed in every cylinder of the internal combustion engine 10 for every fixed crank angle. Further, in the system of the present embodiment, the throttle valve 26 is set to a fully open state, and the output of the internal combustion engine 10 is controlled based on the gasoline injection amount in accordance with the processing of this routine.

  In the routine shown in FIG. 4, first, the engine speed and the accelerator opening are obtained (step 100), and the load factor is calculated based on the engine speed and the accelerator opening (step 102). Next, the fuel pressure and temperature of the hydrogen gas supplied to the hydrogen injector 38 are obtained (step 104).

Next, when the predetermined hydrogen gas injection timing arrives, hydrogen gas is injected into the intake passage 18 by the hydrogen injection valve 38 (step 106). As described above, the hydrogen gas injection timing is set so that the injection is completed during the period from the start of the exhaust stroke of the previous cycle to the end of the intake stroke of the current cycle. The hydrogen injection period τ _H is a value obtained by multiplying the base value τ _Hb by a correction coefficient A based on the hydrogen gas fuel pressure and temperature so that a constant excess air ratio satisfying λ> 3 is realized in a range where no misfire occurs. Is set.

  Next, when the predetermined hydrogen gas ignition timing arrives, ignition of the hydrogen mixture is performed by the spark plug 28 (step 108). Next, gasoline injection is executed almost simultaneously with the end of the hydrogen mixture ignition period (step 110). The ECU 50 stores a map in which the gasoline injection amount (injection period) and the gasoline injection timing are determined by adaptation in relation to the load factor. In step 110, gasoline injection is executed with reference to these maps. In the system of this embodiment, the injection pressure of the gasoline injection valve 30 is set to be higher than the in-cylinder pressure that rises due to lean burn combustion of hydrogen gas.

  According to the routine processing described above, a high-temperature and high-pressure field capable of self-ignition of gasoline is formed by combustion of hydrogen gas, and diffusion combustion using gasoline as fuel can be realized. For this reason, according to the system of this embodiment, in the spark ignition internal combustion engine 10 using gasoline as the main fuel, it is possible to realize an operation capable of reliably suppressing knocking. Further, according to the system of the present embodiment, the throttle valve 26 is fully opened and the output control based on the gasoline injection amount is performed, so that the operation by the diffusion combustion can be performed even in the low load region. Thereby, the pump loss in the throttle valve 26 can be eliminated, and high thermal efficiency can be realized.

  By the way, in Embodiment 1 mentioned above, as shown in the timing chart shown in FIG. 2, it is supposed that gasoline is injected almost at the same time as the end of the hydrogen mixture ignition period, but the gasoline injection timing in the present invention is as follows. As long as the high-temperature and high-pressure field capable of self-ignition of gasoline is maintained, the injection timing is not limited to this. That is, for example, the gasoline injection timing may be substantially the same as the hydrogen ignition by the spark plug 28, or may be a predetermined timing after the hydrogen mixture ignition period has elapsed.

  Furthermore, according to the system of the present embodiment, the heat generation rate at the time of diffusion combustion by gasoline can be controlled by adjusting the interval between the hydrogen mixture ignition period and the gasoline injection timing. More specifically, if the interval between the hydrogen mixture ignition period and the gasoline injection timing is widened, gasoline is injected while the in-cylinder pressure and the in-cylinder temperature are lowered, which may moderate heat generation. It is possible to reduce the load applied to the engine during combustion. When the ignition timing for the hydrogen mixture is changed, the in-cylinder pressure and the in-cylinder temperature at the time of gasoline injection change. That is, according to the system of the present embodiment, the heat generation rate at the time of diffusion combustion can be controlled also by changing the ignition timing for the hydrogen mixture.

In the first embodiment described above, the high temperature and high pressure field is formed in the cylinder by igniting the hydrogen gas, which is a combustible gas, with the spark plug 28. The method using the spark plug 28 is not limited as long as it can form a high-temperature and high-pressure field capable of self-ignition of gasoline during gasoline injection. That is, for example, the high temperature and high pressure gas may be directly supplied into the cylinder. Alternatively, a high temperature and high pressure field may be formed in the cylinder by providing a sub chamber and burning a combustible gas such as hydrogen gas using a spark plug or the like in the sub chamber.
The combustible gas of the present invention may be a gas other than hydrogen gas as long as it has good ignitability and a sufficiently high flame propagation speed.

In the first embodiment described above, the ECU 50 executes the processing of steps 106 and 108, whereby the “high temperature and high pressure field forming means” in the first invention executes the processing of step 110. Thus, the “gasoline supply means” in the first invention is realized.
Further, in the first embodiment described above, the “combustible gas supply means” in the second aspect of the present invention is realized by the ECU 50 executing the processing of step 106.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIGS.
FIG. 5 is a diagram for explaining the configuration of the spark ignition internal combustion engine 60 according to the second embodiment of the present invention. As shown in FIG. 5, the internal combustion engine 60 of this embodiment includes a hydrogen injection valve 62 that directly injects hydrogen gas into the cylinder, instead of the hydrogen injection valve 38 that injects hydrogen gas into the intake passage 18. Except for this point, the configuration is the same as that of the first embodiment described above. Hereinafter, in FIG. 5, the same reference numerals are used for the same elements as those shown in FIG. 1, and the detailed description thereof is omitted or simplified.

  In the first embodiment described above, the hydrogen gas injected into the intake passage 18 is taken into the cylinder as a uniform air-fuel mixture together with air, and then burned. Since hydrogen has good ignitability, combustion at a high excess air ratio λ is possible. However, in the configuration of the first embodiment, there is a limit to increasing the excess air ratio λ because the hydrogen mixture is uniformly taken into the cylinder. The hydrogen combustion in the present invention is performed in order to form a high-temperature and high-pressure field in the cylinder for realizing diffusion combustion by gasoline. Accordingly, there is a demand for reducing the amount of oxygen consumed during hydrogen combustion in order to sufficiently secure the amount of oxygen used during gasoline combustion. Therefore, in the system of the present embodiment, the stratified combustion of the hydrogen gas is performed so that the hydrogen gas is burned at a higher air excess ratio λ as compared with the first embodiment.

  As a specific configuration for that purpose, the hydrogen injection valve 62 shown in FIG. 5 is configured to be able to inject hydrogen gas directly toward the spark plug 28. The configuration for realizing hydrogen stratified combustion is not limited to this, and a recess is provided on the top surface of the piston 12, and the jet of hydrogen gas is directed toward the spark plug 28 by the recess. May be.

  FIG. 6 is a timing chart showing an example of setting of the hydrogen gas injection period and ignition timing, and the gasoline injection timing used in the system of the present embodiment. As shown in FIG. 6, the injection timing of hydrogen gas is set immediately before the ignition timing so that a high-concentration hydrogen gas mixture layer is formed in the vicinity of the spark plug 28. The gasoline injection timing is the same as in the first embodiment.

Next, a series of operations realized based on the setting of the timing chart shown in FIG. 6 described above will be described in detail with reference to FIG.
First, as shown in FIG. 7A, air is taken into the cylinder during the intake stroke, and then, as shown in FIG. It is injected toward the spark plug 28. Next, as shown in FIG. 7C, the hydrogen mixture in the vicinity of the spark plug 28 is ignited at a predetermined ignition timing during the compression stroke. Since hydrogen has good ignitability, super-lean burn combustion with a higher excess air ratio λ (approximately λ> 6) is possible with stratified combustion as compared with uniform combustion. Next, as shown in FIG. 7 (D), gasoline is injected so as to be widely diffused into the cylinder made into a high-temperature and high-pressure field by the combustion of hydrogen gas. As a result, as in the case of the first embodiment, diffusion combustion using gasoline as fuel is realized.

  FIG. 8 is a flowchart of a routine executed by the ECU 64 in order to realize the above functions in the second embodiment. Also in the system of this embodiment, the throttle valve 26 is set to a fully open state, and the output of the internal combustion engine 60 is controlled based on the gasoline injection amount by the processing of this routine. In FIG. 8, the same steps as those shown in FIG. 4 in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted or simplified.

In the routine shown in FIG. 8, when a predetermined hydrogen gas injection timing arrives, hydrogen gas is injected into the cylinder by the hydrogen injection valve 62 (step 112). As described above, the hydrogen gas injection timing is set to be immediately before the ignition timing. In the hydrogen injection period τ _H ′, the base value τ _Hb ′ is based on the fuel pressure and temperature of the hydrogen gas so that a constant excess air ratio that satisfies λ> 6 is realized in the entire combustion chamber 16 within a range where no misfire occurs. A value obtained by multiplying the correction coefficient B is set.

  Next, when the predetermined hydrogen gas ignition timing arrives, ignition of the hydrogen gas mixture is performed by the spark plug 28 (step 108), and gasoline injection is performed at a timing after the time when the hydrogen gas is ignited (step 108). 110).

  According to the routine processing described above, the oxygen consumption during hydrogen combustion can be reduced by performing hydrogen stratified combustion. For this reason, according to the system of the present embodiment, oxygen remaining in the cylinder at the time of gasoline combustion can be effectively utilized as compared with the system of the first embodiment. That is, the torque that can be generated when the same amount of air is sucked into the cylinder can be improved as compared with the system of the first embodiment. Further, the amount of hydrogen used can be saved as compared with the system of the first embodiment.

  By the way, in Embodiment 2 mentioned above, hydrogen stratification combustion is implement | achieved using the hydrogen injection valve 62 which injects hydrogen directly in a cylinder, However, The hydrogen gas supply means of this invention is limited to this is not. For example, the hydrogen gas supply means uses a hydrogen injection valve 38 that injects hydrogen gas into the intake passage 18 and a swirl control valve to form a high-concentration hydrogen mixture layer around the spark plug 28. Also good.

Embodiment 3 FIG.
Next, a third embodiment of the present invention will be described with reference to FIG.
FIG. 9 is a view for explaining the configuration of the spark ignition internal combustion engine 70 according to the third embodiment of the present invention. As shown in FIG. 9, the internal combustion engine 70 of the present embodiment is described above except that a supercharger 72 is provided on the upstream side of the throttle valve 26 in the intake passage 18 so that compressed air can be supplied into the cylinder. The configuration is the same as that of the first embodiment. Also in the system of the present embodiment, the throttle valve 26 is set to a fully open state, and the output of the internal combustion engine 70 is controlled based on the gasoline injection amount according to a routine process similar to the routine shown in FIG. That is, also in this embodiment, diffusion combustion using gasoline as fuel is executed.

  In the following, in FIG. 9, the same reference numerals are used for the same elements as those shown in FIG. 1, and the detailed description thereof is omitted or simplified. Here, hydrogen gas is supplied into the intake passage 18, but this is not limiting, and hydrogen stratified combustion is realized by directly injecting hydrogen gas into the cylinder as in the second embodiment. You may do. Further, the supercharger 72 is not limited to the supercharger shown in FIG. 9, but may be a turbocharger or the like.

Next, the effect by which the system of this embodiment is provided with the supercharger 72 is demonstrated.
In the case of a normal spark ignition type internal combustion engine that ignites a gasoline mixture and burns it, it is necessary to suppress the occurrence of knocking in a high load region including a supercharging region, so that an ignition that provides an ideal torque can be obtained. The angle cannot be advanced at the time, and the torque decreases. On the other hand, according to the gasoline diffusion combustion of the present embodiment, there is a torque reduction factor by the amount of oxygen consumed by hydrogen combustion, but combustion is possible without causing knocking. Therefore, it is easy to generate a desired high torque. In addition to this, according to the system of the present embodiment, by performing supercharging, it is possible to supply in advance a large amount of oxygen for the amount of oxygen consumed by hydrogen combustion into the cylinder, and this is caused by hydrogen combustion. Thus, the peak value of the original torque can be generated without lowering the torque.

  Further, in the case of a normal spark ignition type internal combustion engine, knocking is more likely to occur as the boost pressure is increased, so it is difficult to increase the boost pressure, and the boost pressure is further increased. However, since it is forced to further delay the ignition timing, it is difficult to obtain a desired high torque by increasing the supercharging pressure. On the other hand, according to the system of the present embodiment, it is possible to increase the supercharging pressure without considering knocking, and a desired high torque can be easily obtained. This effect is more prominent as the boost pressure is higher.

  In addition, according to the system of the present embodiment, a sufficient amount of oxygen is supplied into the cylinder by supercharging, and air and gasoline are likely to be mixed. And unburned THC are effectively suppressed.

Embodiment 4 FIG.
Next, a fourth embodiment of the present invention will be described with reference to FIG.
The system of the present embodiment is realized by causing the ECU 52 to execute the routine shown in FIG. 10 using the apparatus configuration of the first embodiment described above.

  In the first embodiment described above, gasoline diffusion combustion is performed using hydrogen gas regardless of the operating state of the internal combustion engine 10 (hereinafter referred to as “gasoline diffusion combustion system”). In contrast, the system of the present embodiment does not always use the gasoline diffusion combustion method, but uses the gasoline diffusion combustion method only in an area where knocking is a concern, and in other areas, hydrogenation is performed. It is characterized in that the gasoline mixture is directly ignited and combusted without being performed (hereinafter referred to as “normal combustion system”).

  FIG. 10 is a flowchart of a routine executed by the ECU 50 in order to realize the above functions in the fourth embodiment. In FIG. 10, the same steps as those shown in FIG. 4 in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted or simplified. In the routine shown in FIG. 10, after the load factor is calculated (step 102), it is determined whether or not it is a knocking risk area (step 114). The ECU 50 stores a map having a region using the gasoline diffusion combustion method and a region using the normal combustion method. This map is set so that the gasoline diffusion combustion method is applied in a low rotation high load region where knocking is a concern, and the normal combustion method is applied in other regions such as a low load region. In this step 114, this map is referred to and it is determined which combustion method is used in the current operation state.

  If it is determined in step 114 that the region is not the knocking risk region, that is, the region where the normal combustion method is used, the gasoline is directly injected into the cylinder at a predetermined injection timing by the gasoline injection valve 30 (step 116). The ECU 50 stores a map in which the gasoline injection amount (injection period) and the gasoline injection timing are determined by adaptation in relation to the load factor. In this step 116, the gasoline injection is executed with reference to these maps so that the gasoline stoichiometric operation is realized. Further, as already described, hydrogenation is not performed here. Next, when a predetermined ignition timing arrives, the gasoline mixture is ignited by the spark plug 28 (step 118). As a result, combustion by flame propagation is performed.

  On the other hand, if it is determined in step 114 that the region is a knocking risk region, that is, a region in which the gasoline diffusion combustion system is used, the same processing as in steps 104, 106, 108, and 110 described above is executed. The As a result, gasoline diffusion combustion is performed.

  According to the routine processing described above, hydrogen is used only in a region where knocking is a concern, and a normal combustion method in which hydrogen is not used in a low load region, which is a normal region, is used. Compared to the system, the total amount of hydrogen used can be saved.

  By the way, in Embodiment 4 mentioned above, in areas other than the area where knocking is a concern, combustion is performed using only gasoline as fuel, but the present invention is not limited to this. In other words, it is not always necessary to perform combustion using only gasoline as a fuel in all regions other than the region where knocking is a concern, and combustion is performed using only gasoline as a fuel in at least some regions other than regions where knocking is a concern. It may be.

  In the above-described fourth embodiment, the ECU 52 is caused to execute the routine shown in FIG. 10 using the apparatus configuration of the first embodiment. However, the present invention is not limited to this, and the second embodiment is not limited to this. The routine shown in FIG. 10 may be executed by the ECU 64 using the apparatus configuration.

  In the above-described fourth embodiment, the “combustion method selection means” according to the seventh aspect of the present invention is realized by the ECU 50 executing the processing of step 114. Further, the gasoline diffusion combustion system corresponds to the “first combustion system” in the seventh invention, and the normal combustion system corresponds to the “second combustion system” in the seventh invention.

It is a figure for demonstrating the structure of the spark ignition internal combustion engine of Embodiment 1 of this invention. It is a timing chart which shows an example of the setting of the injection timing and ignition timing of hydrogen gas used in Embodiment 1 of this invention, and the injection timing of gasoline. FIG. 3 is a diagram conceptually showing the operation of the internal combustion engine based on the setting of the timing chart shown in FIG. 2. It is a flowchart of the routine performed in Embodiment 1 of the present invention. It is a figure for demonstrating the structure of the spark ignition internal combustion engine of Embodiment 2 of this invention. It is a timing chart which shows an example of the setting of the injection timing of hydrogen gas and ignition timing used in Embodiment 2 of this invention, and the injection timing of gasoline. It is a figure which shows notionally the operation | movement of the internal combustion engine based on the setting of the timing chart shown in FIG. It is a flowchart of the routine performed in Embodiment 2 of this invention. It is a figure for demonstrating the structure of the spark ignition internal combustion engine of Embodiment 3 of this invention. It is a flowchart of the routine performed in Embodiment 4 of this invention.

Explanation of symbols

10, 60, 70 Internal combustion engine 16 Combustion chamber 18 Intake passage 20 Exhaust passage 26 Throttle valve 28 Spark plug 30 Gasoline injection valve 38, 62 Hydrogen injection valve 50, 64 ECU (Electronic Control Unit)
72 Turbocharger

Claims (7)

A control device for an internal combustion engine including a gasoline injection valve for directly injecting gasoline into a cylinder,
High-temperature and high-pressure field forming means for forming a high-temperature and high-pressure field capable of gasoline self-ignition in a cylinder;
Gasoline supply means for supplying gasoline into the cylinder at a predetermined timing during a period when the inside of the cylinder is the high temperature and high pressure field by the high temperature and high pressure field forming means,
The control apparatus for an internal combustion engine, wherein the high-temperature and high-pressure field forming unit includes a combustible gas supply unit that supplies a combustible gas into the cylinder, and an ignition plug that ignites the combustible gas supplied into the cylinder.   The control apparatus for an internal combustion engine according to claim 1, wherein the combustible gas is hydrogen gas.   3. The control apparatus for an internal combustion engine according to claim 2, wherein the predetermined timing is a timing that is substantially the same as or delayed from the ignition of the hydrogen gas by the spark plug.   4. The control apparatus for an internal combustion engine according to claim 2, wherein the combustible gas supply means supplies hydrogen gas so that a hydrogen gas mixture is uniformly formed in the cylinder.   4. The control apparatus for an internal combustion engine according to claim 2, wherein the combustible gas supply means supplies hydrogen gas so that a high-concentration hydrogen mixture layer is formed in the vicinity of the spark plug.   The control device for an internal combustion engine according to any one of claims 2 to 5, further comprising a supercharger for supplying compressed air into the cylinder. Combustion method selection means for selecting a combustion method according to the operating state of the internal combustion engine,
The combustion mode selection means selects the first combustion mode that realizes combustion using the gasoline supply means in an area where knocking is a concern, and in other areas, only gasoline is used as fuel and gasoline and air are used. The internal combustion engine control apparatus according to any one of claims 2 to 6, wherein a second combustion system that realizes combustion by directly igniting the air-fuel mixture with the spark plug can be selected.

Images