JP2018040264A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate an intended time difference of compression self-ignition timing of pre-mixed air fuel mixture and thus disperse heat generation timing.SOLUTION: A control device 200 for an internal combustion engine 100 includes: a combustion control section for controlling injection amount and injection timing of a fuel injection valve 20 and ignition timing of an ignition plug 16 so that ignition assist self-ignition combustion for performing flame propagation combustion of part of fuel by using the ignition plug 16 and by using heat generated at this time, performing pre-mixed compression self-ignition combustion of remaining fuel is generated in a combustion chamber; and an ozone supply amount control section for controlling ozone supply amount to the combustion chamber by using an ozone supply device 81. The combustion control section controls the injection amount and injection timing of the fuel injection valve and the ignition timing of the ignition plug 16 so that predicted self-ignition timing when the ignition assist self-ignition combustion is performed becomes target self-ignition timing. The ozone supply amount control section is configured to control the ozone supply amount on the basis of the fuel amount used for the pre-mixed compression self-ignition combustion.SELECTED DRAWING: Figure 1

Description

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

  In Patent Document 1, as a control device for a conventional internal combustion engine, ozone is supplied so that a difference in concentration occurs in the combustion chamber and premixed compression autoignition combustion is performed. An apparatus configured to disperse the heat generation time by causing a time difference is disclosed.

JP 2001-323829 A

  However, in the above-described conventional control device for an internal combustion engine, when the compression ignition timing of the premixed gas advances from the target ignition timing due to, for example, a change in the outside air temperature, the compression ignition timing of the premixed gas is set. In order to control the target self-ignition timing, it is necessary to reduce the ozone supply amount and increase the ignition delay time of the premixed gas. In this case, the difference in ozone concentration also becomes small, so that it becomes difficult to cause a time difference in the compression auto-ignition timing of the premixed gas, and the heat generation timing cannot be sufficiently dispersed.

  The present invention has been made paying attention to such problems, and even when the compression auto-ignition timing of the premixed gas is shifted from the target auto-ignition timing due to changes in the outside air temperature, etc. It is an object of the present invention to provide a desired time difference in the compression ignition timing of the premixed gas so that the heat generation timing can be dispersed.

  In order to solve the above problems, according to an aspect of the present invention, an engine body, a fuel injection valve for directly injecting fuel into a combustion chamber of the engine body, and an ignition plug disposed so as to face the combustion chamber And an ozone supply device for supplying ozone directly or indirectly to the combustion chamber so that a difference in concentration occurs in the combustion chamber. The fuel injection valve injection amount and the injection amount are set such that ignition assist auto-ignition combustion occurs in the combustion chamber in which the ignition plug causes the remaining fuel to be premixed compression auto-ignition combustion using the heat generated by the spark plug. A combustion control unit that controls the timing and the ignition timing of the spark plug; and an ozone supply amount control unit that controls the amount of ozone supplied to the combustion chamber by the ozone supply device. The combustion control unit controls the injection amount and injection timing of the fuel injection valve and the ignition timing of the spark plug so that the expected self-ignition timing when the ignition assist self-ignition combustion is performed becomes the target self-ignition timing. The ozone supply amount control unit is configured to control the ozone supply amount based on the amount of the remaining fuel to be premixed compression self-ignition combustion.

  According to this aspect of the present invention, the compression ignition timing of the premixed gas even when the compression ignition timing of the premixed gas deviates from the target ignition timing due to a change in the outside air temperature or the like. It is possible to disperse the heat generation time by producing a desired time difference.

FIG. 1 is a schematic configuration diagram of an internal combustion engine and an electronic control unit that controls the internal combustion engine according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the engine body of the internal combustion engine according to the embodiment of the present invention. FIG. 3A is a schematic view of a cylinder of an internal combustion engine according to an embodiment of the present invention as viewed from the cylinder head side. FIG. 3B is a schematic view of the cylinder of the internal combustion engine according to the first modification of the present invention as viewed from the cylinder head side. FIG. 3C is a schematic view of the cylinder of the internal combustion engine according to the second modification of the present invention as viewed from the cylinder head side. FIG. 4 is a diagram showing an operation region of the engine body. FIG. 5A is a diagram illustrating an example of the opening operation of the intake valve and the exhaust valve during the CI operation mode. FIG. 5B is a diagram illustrating an example of the opening operation of the intake valve and the exhaust valve during the CI operation mode. FIG. 6 is a diagram showing the relationship between the crank angle and the heat generation rate when compression autoignition combustion is performed. It is the figure which showed the relationship between the crank angle at the time of implementing ignition assistance self-ignition combustion, supplying ozone during an intake stroke so that a concentration difference may arise in a combustion chamber. FIG. 8A is a flowchart illustrating combustion control and ozone supply control during the CI operation mode according to an embodiment of the present invention. FIG. 8B is a flowchart illustrating combustion control and ozone supply control during the CI operation mode according to an embodiment of the present invention. FIG. 9 is a map for calculating the injection ratio R of the ignition assist fuel based on the engine operating state. FIG. 10 calculates a correction coefficient to be multiplied by the injection ratio R of the ignition assist fuel, a target injection timing of the ignition assist fuel, and a retardation correction amount to be added to the target ignition assist timing based on the advance angle deviation amount. It is a table for. FIG. 11 is a map for calculating the target ozone supply amount based on the engine rotation speed and the main fuel injection amount. FIG. 12 calculates a correction coefficient by which the injection ratio of the ignition assist fuel is multiplied, a target injection timing of the ignition assist fuel, and an advance correction amount γ to be subtracted from the target ignition assist timing, based on the retardation shift amount. It is a table for.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same reference numerals are assigned to similar components.

  First, the configuration of an internal combustion engine 100 and an electronic control unit 200 that controls the internal combustion engine 100 according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3A. FIG. 1 is a schematic configuration diagram of an internal combustion engine 100 and an electronic control unit 200 for controlling the internal combustion engine 100 according to the present embodiment. FIG. 2 is a schematic cross-sectional view of the engine body 1 of the internal combustion engine 100. FIG. 3A is a schematic view of the cylinder 10 as viewed from the cylinder head side.

  The internal combustion engine 100 includes an engine body 1 having a plurality of cylinders 10, a fuel supply device 2, an intake device 3, an exhaust device 4, an intake valve device 5, and an exhaust valve device 6.

  The engine body 1 burns fuel in a combustion chamber 11 (see FIG. 2) formed in each cylinder 10 to generate power for driving a vehicle, for example. The engine body 1 is provided with one spark plug 16 for each cylinder so as to face the combustion chamber 11 of each cylinder 10, and a pair of intake valves 50 and a pair of exhaust valves 60 are provided for each cylinder. As shown in FIG. 2, pistons 12 that reciprocate within the cylinders 10 are received inside the cylinders 10 by receiving combustion pressure. The piston 12 is connected to a crankshaft via a connecting rod, and the reciprocating motion of the piston 12 is converted into rotational motion by the crankshaft.

  The fuel supply device 2 includes an electronically controlled fuel injection valve 20, a delivery pipe 21, a supply pump 22, a fuel tank 23, and a pressure feed pipe 24.

  The fuel injection valve 20 is disposed at the center top of the combustion chamber 11, and one fuel injection valve 20 is provided in each cylinder 10 so as to face the combustion chamber 11 of each cylinder 10. As shown in FIG. 2, in this embodiment, the electrode portion 16 a of the spark plug 16 is adjacent to the spark plug 16 so as to be located in the fuel injection region R of the fuel injection valve 20 or in the vicinity of the fuel injection region R. By disposing the fuel injection valve 20, a so-called spray guide for igniting the fuel spray in the fuel injection region R or in the vicinity of the fuel injection region R immediately after the fuel injection can be performed. . The valve opening time (injection amount) and valve opening timing (injection timing) of the fuel injection valve 20 are changed by a control signal from the electronic control unit 200. When the fuel injection valve 20 is opened, the fuel injection valve 20 changes to the combustion chamber. The fuel is directly injected into 11.

  The delivery pipe 21 is connected to the fuel tank 23 via a pressure feed pipe 24. A supply pump 22 for pressurizing the fuel stored in the fuel tank 23 and supplying it to the delivery pipe 21 is provided in the middle of the pressure feeding pipe 24. The delivery pipe 21 temporarily stores the high-pressure fuel pumped from the supply pump 22. When the fuel injection valve 20 is opened, the high-pressure fuel stored in the delivery pipe 21 is directly injected into the combustion chamber 11 from the fuel injection valve 20. The delivery pipe 21 is provided with a fuel pressure sensor 211 for detecting the fuel pressure in the delivery pipe 21, that is, the pressure (injection pressure) of the fuel injected from the fuel injection valve 20 into the cylinder.

  The supply pump 22 is configured to be able to change the discharge amount, and the discharge amount of the supply pump 22 is changed by a control signal from the electronic control unit 200. By controlling the discharge amount of the supply pump 22, the fuel pressure in the delivery pipe 21, that is, the injection pressure of the fuel injection valve 20 is controlled.

  The intake device 3 is a device for guiding intake air into the combustion chamber 11 and changes the state of intake air (intake pressure, intake air temperature, EGR (Exhaust Gas Recirculation) gas amount) sucked into the combustion chamber 11. It is configured to be able to. The intake device 3 includes an intake passage 30, an intake manifold 31, and an EGR passage 32.

  One end of the intake passage 30 is connected to the air cleaner 34, and the other end is connected to the intake collector 31 a of the intake manifold 31. In the intake passage 30, an air flow meter 212, a compressor 71 of the exhaust turbocharger 7, an intercooler 35, and a throttle valve 36 are provided in order from the upstream.

  The air flow meter 212 detects the flow rate of air that flows through the intake passage 30 and is finally sucked into the cylinder 10.

  The compressor 71 includes a compressor housing 71a and a compressor wheel 71b disposed in the compressor housing 71a. The compressor wheel 71b is rotationally driven by the turbine wheel 72b of the exhaust turbocharger 7 mounted on the same axis, and compresses and discharges the intake air flowing into the compressor housing 71a. The turbine 72 of the exhaust turbocharger 7 is provided with a variable nozzle 72c for controlling the rotational speed of the turbine wheel 72b. By controlling the rotational speed of the turbine wheel 72b by the variable nozzle 72c, the compressor housing 71a. The pressure (supercharging pressure) of the intake air discharged from the inside is controlled.

  The intercooler 35 is a heat exchanger for cooling the intake air that has been compressed by the compressor 71 to a high temperature, for example, with traveling wind, cooling water, or the like.

  The throttle valve 36 adjusts the amount of intake air introduced into the intake manifold 31 by changing the cross-sectional area of the intake passage 30. The throttle valve 36 is driven to open and close by a throttle actuator 36a, and its opening (throttle opening) is detected by a throttle sensor 213.

  The intake manifold 31 is connected to an intake port 14 formed in the engine body 1, and the intake air flowing in from the intake passage 30 is evenly distributed into the combustion chamber 11 of each cylinder 10 via the intake port 14. . An intake collector 31a of the intake manifold 31 detects an intake pressure sensor 214 for detecting the pressure of intake air (intake pressure) sucked into the cylinder and a temperature of intake air (intake air temperature) sucked into the cylinder. An intake air temperature sensor 215 is provided.

  The EGR passage 32 communicates the exhaust manifold 41 and the intake collector 31a of the intake manifold 31, and is a passage for returning a part of the exhaust discharged from each cylinder 10 to the intake collector 31a by a pressure difference. Hereinafter, the exhaust gas flowing into the EGR passage 32 is referred to as “EGR gas”. By recirculating the EGR gas to the intake collector 31a and thus to each cylinder 10, the combustion temperature can be reduced and the emission of nitrogen oxides (NOx) can be suppressed. The EGR passage 32 is provided with an EGR cooler 37 and an EGR valve 38 in order from the upstream.

  The EGR cooler 37 is a heat exchanger for cooling the EGR gas with, for example, traveling wind or cooling water.

  The EGR valve 38 is an electromagnetic valve whose opening degree can be adjusted continuously or stepwise, and the opening degree is controlled by the electronic control unit 200 according to the engine operating state. By controlling the opening degree of the EGR valve 38, the flow rate of the EGR gas to be recirculated to the intake collector 31a is adjusted.

  The exhaust device 4 is a device for discharging exhaust gas from the inside of the cylinder, and includes an exhaust manifold 41 and an exhaust passage 42.

  The exhaust manifold 41 is connected to an exhaust port 15 formed in the engine body 1, and exhausts exhausted from the cylinders 10 are collectively introduced into the exhaust passage 42.

  The exhaust passage 42 is provided with a turbine 72 of the exhaust turbocharger 7 and an exhaust aftertreatment device 43 in order from the upstream.

  The turbine 72 includes a turbine housing 72a and a turbine wheel 72b disposed in the turbine housing 72a. The turbine wheel 72b is rotationally driven by the energy of the exhaust gas flowing into the turbine housing 72a, and drives the compressor wheel 71b mounted coaxially.

  The variable nozzle 72c described above is provided outside the turbine wheel 72b. The variable nozzle 72 c functions as a throttle valve, and the nozzle opening (valve opening) of the variable nozzle 72 c is controlled by the electronic control unit 200. By changing the nozzle opening degree of the variable nozzle 72c, the flow rate of the exhaust for driving the turbine wheel 72b can be changed in the turbine housing 72a. That is, by changing the nozzle opening degree of the variable nozzle 72c, the supercharging pressure can be changed by changing the rotational speed of the turbine wheel 72b. Specifically, when the nozzle opening of the variable nozzle 72c is reduced (the variable nozzle 72c is throttled), the exhaust flow rate increases, the rotational speed of the turbine wheel 72b increases, and the supercharging pressure increases.

  The exhaust aftertreatment device 43 is a device for purifying exhaust gas and discharging it to the outside air, and includes various exhaust purification catalysts for purifying harmful substances, filters for collecting harmful substances, and the like.

  The intake valve operating device 5 is a device for opening and closing the intake valve 50 of each cylinder 10 and is provided in the engine body 1. The intake valve operating device 5 according to the present embodiment is configured to open and close the intake valve 50 by, for example, an electromagnetic actuator so that the opening and closing timing of the intake valve 50 can be controlled to an arbitrary timing. However, the present invention is not limited to this, and the intake valve 50 is configured to open and close by the intake camshaft, and a variable valve that changes the relative phase angle of the intake camshaft with respect to the crankshaft by hydraulic control at one end of the intake camshaft. By providing a mechanism, the opening / closing timing of the intake valve 50 may be controlled to an arbitrary timing.

  The exhaust valve device 6 is a device for opening and closing the exhaust valve 60 of each cylinder 10 and is provided in the engine body 1. The exhaust valve operating device 6 according to the present embodiment is configured so that the exhaust valve 60 of each cylinder 10 can be opened during the exhaust stroke, and can also be opened during the intake stroke as necessary. In this embodiment, an electromagnetic actuator controlled by the electronic control unit 200 is adopted as such an exhaust valve operating device 6, and the exhaust valve 60 of each cylinder 10 is driven to open and close by the electromagnetic actuator, thereby opening and closing the exhaust valve 60. The timing and lift amount are controlled to an arbitrary timing and lift amount. The exhaust valve operating device 6 is not limited to an electromagnetic actuator, and a valve operating device that changes the opening / closing timing and the lift amount of the exhaust valve 60 by changing the cam profile by, for example, hydraulic pressure can also be adopted.

  As shown in FIGS. 1 and 3A, the internal combustion engine 100 according to the present embodiment further includes a discharge plug 81 as an ozone supply device. One discharge plug 81 is provided for each cylinder 10 so as to face the combustion chamber 11 of each cylinder 10. The discharge plug 81 is controlled by the electronic control unit 200, converts oxygen in the combustion chamber 11 into ozone by discharge (silent discharge, corona discharge, streamer discharge, etc.), and supplies ozone into the combustion chamber 11.

  As shown in FIG. 3A, in the present embodiment, the discharge plug 81 is arranged with a bias with respect to the center of the cylinder 10 and between the combustion chamber opening 14a of the intake port 14 and the combustion chamber opening 15a of the exhaust port 15. Is arranged. In the present embodiment, the intake air sucked into the combustion chamber 11 from one combustion chamber opening 14a of the intake port 14 and the intake air sucked into the combustion chamber 11 from the other combustion chamber opening 14b are combusted. In order to suppress mixing in the chamber 11, intake air sucked into the combustion chamber 11 from the combustion chamber opening 14 a and the combustion chamber opening 14 b causes a tumble flow in the combustion chamber 11. Port 14 is formed.

  Thus, ozone is generated by the discharge plug 81 during the intake stroke, so that the ozone concentration in the region where the intake air mainly sucked from the combustion chamber opening 14a of the intake port 14 exists in the combustion chamber 11 The ozone concentration in the region where the intake air sucked from the combustion chamber opening 14b of the port 14 mainly exists can be made higher. As described above, in the present embodiment, ozone can be supplied so that a concentration difference occurs in the combustion chamber 11.

  In addition, the method of supplying ozone so that a density | concentration difference may arise in the combustion chamber 11 is not restricted to such a method.

  For example, as in the internal combustion engine 100 according to the first modification of the present embodiment shown in FIG. 3B, the intake port 14 has a 1 in the intake port 14 so that ozone is included in the intake air mainly sucked into the combustion chamber 11 from the combustion chamber opening 14 a. Two discharge plugs 81 may be provided. Further, as in the internal combustion engine 100 according to the second modified example of the present embodiment of FIG. 3C, ozone is contained in the intake air sucked into the combustion chamber 11 from the combustion chamber opening 14a and the combustion chamber opening 14b, respectively. Two discharge plugs 81 may be provided, and the amount of ozone generated by each discharge plug 81 may be varied.

  Although not shown, ozone can be supplied so that a difference in concentration occurs in the combustion chamber 11 by injecting ozone generated in advance into the combustion chamber 11 or the intake port 14 by an injection valve or the like. You may comprise an ozone supply apparatus so that it can do.

  The electronic control unit 200 is composed of a digital computer and is connected to each other by a bi-directional bus 201. 206.

  In addition to the output signal from the fuel pressure sensor 211 and the like, the input port 205 includes a water temperature sensor 219 for detecting the cooling water temperature for cooling the engine body 1, a humidity sensor 220 for detecting the humidity of the outside air, and An output signal from the fuel property sensor 221 and the like for detecting the fuel property of the fuel supplied to the fuel tank 23 is input via the corresponding AD converter 207. Also, the output voltage of the load sensor 217 that generates an output voltage proportional to the amount of depression of the accelerator pedal 231 (hereinafter referred to as “accelerator depression amount”) as a signal for detecting the engine load corresponds to the input port 205. Is input via the AD converter 207. The input port 205 is supplied with an output signal of a crank angle sensor 218 that generates an output pulse every time the crankshaft of the engine body 1 rotates, for example, 15 °, as a signal for calculating the engine rotational speed and the like. As described above, output signals of various sensors necessary for controlling the internal combustion engine 100 are input to the input port 205.

  The output port 206 is connected to each control component such as the fuel injection valve 20 via a corresponding drive circuit 208.

  The electronic control unit 200 controls the internal combustion engine 100 by outputting a control signal for controlling each control component from the output port 206 based on the output signals of various sensors input to the input port 205. Hereinafter, control of the internal combustion engine 100 performed by the electronic control unit 200 will be described.

  The electronic control unit 200 determines the operation mode of the engine body 1 based on the engine operation state (engine rotation speed and engine load) as a spark ignition operation mode (hereinafter referred to as “SI operation mode”) or a compression ignition operation mode ( (Hereinafter referred to as “CI operation mode”).

  Specifically, the electronic control unit 200 switches the operation mode to the CI operation mode if the engine operation state is in the self-ignition region RR surrounded by the solid line in FIG. 4, and puts it in a region other than the self-ignition region RR. For example, the operation mode is switched to the SI operation mode. The electronic control unit 200 performs combustion control according to each operation mode.

  When the operation mode is the SI operation mode, the electronic control unit 200 basically forms a premixed gas near the stoichiometric air fuel ratio or near the stoichiometric air fuel ratio in the combustion chamber 11 and performs ignition by the spark plug 16, and the premixing is performed. The engine body 1 is operated with the flame propagating and burning.

  In addition, when the operation mode is the CI operation mode, the electronic control unit 200 basically forms a premixed gas with an air / fuel ratio leaner than the stoichiometric air / fuel ratio (for example, about 30 to 40) in the combustion chamber 11, The engine body 1 is operated by burning the air-fuel mixture by compression ignition. In the present embodiment, a stratified premixed gas having a combustible layer in the central portion of the combustion chamber 11 as the premixed gas and an air layer around the inner wall surface of the cylinder is formed. As will be described later, in this embodiment, when the premixed gas is subjected to compression self-ignition combustion in the combustion chamber 11, a part of the fuel is flame-propagated and combusted by the spray guide, and the in-cylinder temperature is generated using the heat generated at that time. Is forcibly raised to perform ignition-assisted self-ignition combustion in which the remaining fuel is subjected to compression self-ignition combustion. By performing such ignition assist and causing the premixed gas to undergo compression self-ignition combustion, the premixed gas can be compressed and self-ignited and combusted even when the in-cylinder temperature is relatively low. It becomes easy to control the ignition timing of the air-fuel mixture to an arbitrary timing.

  Premixed compression auto-ignition combustion can be performed even when the air-fuel ratio is lean as compared with flame propagation combustion, and can be performed even when the compression ratio is increased. Therefore, by performing premixed compression auto-ignition combustion, fuel efficiency can be improved and thermal efficiency can be improved. In addition, since premixed compression self-ignition combustion has a lower combustion temperature than flame propagation combustion, generation of NOx can be suppressed. Furthermore, since there is sufficient oxygen around the fuel, the generation of unburned HC can be suppressed.

  In order to perform premixed compression self-ignition combustion, it is necessary to raise the in-cylinder temperature to a temperature at which the premixed gas can be self-ignited, and the premixed gas is burned into the combustion chamber as in the SI operation mode. It is necessary to make the in-cylinder temperature higher than in the case where all the flame propagation combustion is performed in the cylinder 11. Therefore, in this embodiment, for example, as shown in FIGS. 5A and 5B, during the CI operation mode, the exhaust valve operating device 6 is set so that the exhaust valve 60 opens in the intake stroke in addition to the exhaust stroke as necessary. I have control. In this manner, by performing the opening operation of the exhaust valve twice to open the exhaust valve 60 again during the intake stroke, the high-temperature exhaust discharged from the own cylinder during the exhaust stroke is transferred to the own cylinder during the immediately following intake stroke. Can be sucked back. Thus, the in-cylinder temperature is raised, and the in-cylinder temperature of each cylinder 10 is maintained at a temperature at which premixed compression self-ignition combustion can be performed.

As shown in FIG. 5A, if the exhaust valve 60 is opened when the lift amount of the intake valve 50 is small,
Since a large amount of exhaust gas can be sucked back into the cylinder, the in-cylinder temperature can be greatly increased. On the other hand, as shown in FIG. 5B, if the exhaust valve 60 is opened after the lift amount of the intake valve 50 has increased to some extent, the exhaust air is sucked back after a certain amount of air (fresh air) is sucked into the cylinder. Therefore, the amount of exhaust gas sucked back into the cylinder can be suppressed, and the increase in the in-cylinder temperature can be suppressed. In this way, the increase range of the in-cylinder temperature can be controlled according to the timing at which the exhaust valve opening operation is performed twice. In the present embodiment, the ratio of the EGR gas amount in the in-cylinder gas amount and the exhaust amount sucked back into the own cylinder is referred to as an EGR rate.

  By the way, when the premixed gas is compressed and self-ignited and combusted, the fuel diffused in the combustion chamber 11 is self-ignited at multiple points at the same time. Therefore, there is a problem that combustion noise increases compared with the case where the premixed gas is subjected to flame propagation combustion.

  FIG. 6 shows that a predetermined amount of fuel corresponding to the engine load is injected only once from the fuel injection valve 20 at an arbitrary time from the intake stroke to the compression stroke (−50 [deg. ATDC] in the example of FIG. 6). FIG. 6 is a diagram showing the relationship between the crank angle and the heat release rate when performing compression auto-ignition combustion. Heat generation rate (dQ / dθ) [J / deg. CA] is the amount of heat per unit crank angle generated by the combustion of the premixed gas, that is, the amount of heat generation Q per unit crank angle. In the following description, the combustion waveform indicating the relationship between the crank angle and the heat generation rate is referred to as a “heat generation rate pattern” as necessary.

As described above, when the premixed gas is subjected to compression self-ignition combustion, the fuel diffused in the combustion chamber 11 is self-ignited at multiple points at the same time, so that the combustion speed is higher than that in the case of flame propagation combustion. Faster and shorter combustion period. Therefore, as shown in FIG. 6, when the premixed gas is subjected to compression auto-ignition combustion, the peak value of the heat generation rate pattern and the slope of the heat generation rate pattern in the initial stage of combustion (the area shown by hatching in FIG. 6) ( Each of d ² Q / (dθ) ² ) tends to be relatively large.

  The combustion noise has a correlation with each of the peak value of the heat generation rate pattern and the inclination at the initial stage of combustion, and increases as the peak value of the heat generation rate pattern increases and the inclination at the initial stage of combustion increases. Therefore, when the premixed gas is subjected to compression auto-ignition combustion, combustion noise increases compared to when the premixed gas is subjected to flame propagation combustion.

  Here, as a method of reducing each of the peak value of the heat generation rate pattern and the inclination in the early stage of combustion to reduce the combustion noise, by supplying ozone so that a concentration difference occurs in the combustion chamber 11, the time difference is reduced. There is a method of providing compression autoignition combustion in stages.

  The ozone supplied into the combustion chamber 11 is decomposed when the temperature in the combustion chamber 11 rises to a predetermined temperature (for example, about 500 [K] to 600 [K]), and generates oxygen radicals which are a kind of active species. Let It is known that oxygen radicals act on fuel molecules to increase the self-ignition property of the fuel. The greater the amount of oxygen radicals present in the combustion chamber 11, the earlier the self-ignition timing of the premixed gas.

  Therefore, by supplying ozone so that a concentration difference is generated in the combustion chamber 11, the combustion chamber 11 is compared with the self-ignition timing of the premixed gas existing in the region where the ozone concentration is relatively high in the combustion chamber 11. The self-ignition timing of the premixed gas existing in the region where the ozone concentration is relatively low can be delayed. That is, by supplying ozone so that a concentration difference is generated in the combustion chamber 11, compression auto-ignition combustion can be generated step by step with a time difference.

  FIG. 7 shows a case where ignition assist self-ignition combustion is performed without changing the total amount of fuel injected from the fuel injection valve 20 while supplying ozone during the intake stroke so that a concentration difference occurs in the combustion chamber 11. It is the figure which showed the relationship between a crank angle and a heat release rate.

  In FIG. 7, the heat generation rate pattern A is a heat generation rate pattern when the premixed gas existing in a region having a relatively high ozone concentration in the combustion chamber 11 is subjected to compression auto-ignition combustion. The heat release rate pattern B is a heat release rate pattern when a premixed gas present in a region having a relatively low ozone concentration in the combustion chamber 11 undergoes compression autoignition combustion. The heat release rate pattern C is an actual heat release rate pattern obtained by adding the heat release rate pattern A and the heat release rate pattern B together. The heat release rate pattern D is the heat release rate pattern of FIG. 6 shown for comparison.

  As shown in FIG. 7, when the ignition assist is performed and the premixed gas is subjected to compression self-ignition combustion, first, the main fuel and the ignition assist fuel are sequentially injected from the fuel injection valve 20. Then, the main fuel is injected at an arbitrary time during the compression stroke from the intake stroke (−50 [deg. ATDC] in the example of FIG. 7) to form a premixed gas in the combustion chamber. In addition, the ignition assist fuel is injected at an arbitrary time in the latter half of the compression stroke after the main fuel is injected (−10 [deg. ATDC] in the example of FIG. 7). Forms a rich air / fuel mixture. In the example shown in FIG. 7, the main fuel is injected only once during the compression stroke. However, the main fuel may be injected in a plurality of times.

  Next, ignition (ignition assist) is performed by the spark plug 16 on the rich mixture at an arbitrary timing (ignition assist timing shown in FIG. 7) in the latter half of the compression stroke after injection of the ignition assist fuel. The rich air-fuel mixture (ignition assist fuel) is subjected to flame propagation combustion, and the in-cylinder temperature is forcibly increased using the heat generated at that time, whereby the pre-air mixture (main fuel) is subjected to compression self-ignition combustion. By performing such ignition assist and causing the premixed gas to undergo compression self-ignition combustion, the premixed gas can be compressed and self-ignited and combusted even when the in-cylinder temperature is relatively low. It becomes easy to control the ignition timing of the air-fuel mixture to an arbitrary timing. In addition, since a part of the fuel is subjected to flame propagation combustion, the amount of fuel consumed by the compression auto-ignition combustion is reduced. Therefore, combustion noise can be reduced as compared with the case where all fuel is consumed by premixed compression auto-ignition combustion.

  At this time, if ozone is supplied so as to cause a concentration difference in the combustion chamber 11, as shown in the heat generation rate pattern A, premixing that exists in a region where the ozone concentration is relatively high in the combustion chamber 11. I start self-ignition first. And as shown in the heat release rate pattern B, the premixed gas present in the region where the ozone concentration is relatively low in the combustion chamber 11 is delayed to cause self-ignition.

  The peak value of each of the heat generation rate pattern A and the heat generation rate pattern B and the slope at the beginning of combustion are smaller than the peak value of the heat generation rate pattern D and the slope at the beginning of combustion. This contributes to the formation of the heat generation rate pattern A as compared with the amount of fuel that contributes to the formation of the heat generation rate pattern D because the total amount of fuel injection does not change in both the case of FIG. 6 and FIG. This is because the amount of fuel to be generated and the amount of fuel contributing to the formation of the heat release rate pattern B are reduced, and the amount of fuel ignited at the same time is dispersed. As a result, as shown in FIG. 7, the peak value of the heat generation rate pattern C, which is an actual combustion waveform, and the slope at the initial stage of combustion (the area indicated by hatching in FIG. 7) are also the peak value of the heat generation rate pattern D and It becomes smaller than the inclination in the early stage of combustion. Therefore, combustion noise can be reduced by providing a time difference in this manner and causing compression auto-ignition combustion in stages.

  Here, when carrying out the ignition assist self-ignition combustion, the main fuel injection amount and injection timing, the ignition assist fuel injection amount, the injection timing and the target value of the ignition assist timing are respectively set according to the engine operating state, The fuel injection valve 20 and the spark plug 16 are controlled according to each target value. In addition, various parameters (for example, intake air temperature, intake air pressure, intake valve closing timing, EGR rate, cooling water temperature, etc.) that affect compression self-ignition combustion are also controlled to target values according to the engine operating state.

  However, during engine operation, these parameters may be transiently not controlled to target values corresponding to the engine operation state. In such a case, the self-ignition time may be advanced or retarded from the expected self-ignition time (target self-ignition time). Even if each of these parameters is controlled to a target value corresponding to the engine operating state, the self-ignition timing is advanced or retarded from the target self-ignition timing depending on, for example, the humidity and fuel properties of the outside air. Sometimes.

  Thus, if the self-ignition timing is advanced or retarded from the target self-ignition timing, combustion noise may increase, output may decrease, and exhaust emission may deteriorate.

  For example, when the intake air temperature is higher than the target value, the in-cylinder temperature at the same crank angle is higher than when the intake air temperature is controlled to the target value. Therefore, even when the ignition assist timing is the same, the self-ignition timing is advanced compared to when the intake air temperature is controlled to the target value. If it does so, while the amount of fuel consumed by flame propagation combustion will decrease from assumption, the amount of fuel consumed by premixed compression auto-ignition combustion will increase rather than assumption.

  As a result, even if the ozone concentration difference in the combustion chamber 11 is the same, the amount of fuel consumed by the premixed compression auto-ignition combustion is increased to an area where the ozone concentration is relatively high in the combustion chamber 11. There is no time difference between the self-ignition timing of the premixed gas present and the self-ignition timing of the premixed gas present in the combustion chamber 11 in a region where the ozone concentration is relatively low. That is, the self-ignition timing of the premixed gas existing in a region having a relatively high ozone concentration in the combustion chamber 11 and the self-ignition timing of the premixed gas existing in a region having a relatively low ozone concentration in the combustion chamber 11. And the interval between the two becomes shorter, the effect of suppressing the peak value of the heat generation rate pattern and the inclination in the early stage of combustion is reduced, and the combustion noise may not be sufficiently reduced.

  On the other hand, for example, when the intake air temperature is lower than the target value, the in-cylinder temperature at the same crank angle is lower than when the intake air temperature is controlled to the target value. Therefore, even when the ignition assist timing is the same, the self-ignition timing is retarded compared to when the intake air temperature is controlled to the target value. If it does so, while the amount of fuel consumed by flame propagation combustion will increase rather than assumption, the amount of fuel consumed by premixed compression auto-ignition combustion will decrease rather than assumption.

  As a result, even if the ozone concentration difference in the combustion chamber 11 is the same, the amount of fuel consumed by the premixed compression auto-ignition combustion is reduced to an area where the ozone concentration is relatively high in the combustion chamber 11. The interval between the self-ignition timing of the existing premixed gas and the self-ignition timing of the premixed gas existing in the region where the ozone concentration is relatively low in the combustion chamber 11 becomes long. For this reason, the combustion gravity center position of the heat generation rate pattern (the position at which the fuel combustion ratio is 50% and the position at which the heat generation rate is approximately the peak value) is too retarded and the output may decrease. Moreover, since the amount of fuel consumed by flame propagation combustion increases more than expected, there is a possibility that NOx increases and exhaust emission deteriorates.

  Therefore, in the present embodiment, when the self-ignition timing is expected to advance or retard from the target self-ignition timing, the self-ignition timing is controlled by controlling the injection amount of the ignition assist fuel, the injection timing, and the ignition assist timing. Is controlled to the target self-ignition timing, and the ozone supply amount is controlled in accordance with the injection amount of the main fuel so that the compression self-ignition combustion is generated stepwise with a desired time difference.

  Hereinafter, combustion control and ozone supply control during the CI operation mode according to this embodiment will be described.

  8A and 8B are flowcharts illustrating combustion control and ozone supply control during the CI operation mode according to the present embodiment. The electronic control unit 200 repeatedly executes this routine at a predetermined calculation cycle (for example, 10 [ms]) during the CI operation mode.

  In step S1, the electronic control unit 200 reads the engine rotational speed calculated based on the output signal of the crank angle sensor 218 and the engine load detected by the load sensor 217, and detects the engine operating state.

In step S2, the electronic control unit 200 calculates a total fuel injection amount Q _INJ based on the engine load with reference to a table created in advance through experiments or the like. The total fuel injection amount Q _INJ increases as the engine load increases.

  In step S3, the electronic control unit 200 calculates an injection ratio R [%] of the ignition assist fuel based on the engine operating state with reference to the map of FIG. As shown in the map of FIG. 9, the injection ratio R of the ignition assist fuel decreases as the engine load increases and increases as the engine speed increases.

In step S4, the electronic control unit 200 calculates the target injection amount Q _INJ 2 of the ignition assist fuel by multiplying the total fuel injection amount Q _INJ by the injection ratio R of the ignition assist fuel. Further, the electronic control unit 200 calculates the target injection amount Q _INJ 1 of the main fuel by subtracting the target injection amount Q _INJ 2 of the ignition assist fuel from the total fuel injection amount Q _INJ .

In step S5, the electronic control unit 200 refers to the map created in advance by experiment or the like, based on the engine operating state, the target injection timing A _{INJ 1} of the main _fuel, target injection timing A _{INJ 2} of assisting ignition fuel, And the target ignition assist timing IG by the spark plug 16 is calculated.

In the present embodiment, the target injection timing A _INJ 1 of the main fuel is set to an arbitrary timing (for example, about 30 [deg. BTDC] to 80 [deg. BTDC]) based on the operating state.

Further, in the present embodiment, the target injection timing A _INJ 2 of the ignition assist fuel is set to an arbitrary timing (for example, 10 [10] in the latter half of the compression stroke that is retarded from the target injection timing A _INJ 1 of the main fuel based on the engine operating state. deg.BTDC] to 35 [deg.BTDC]).

Further, in the present embodiment, the target ignition assist timing IG is a timing on the advance side or the retard side with _{respect to} the target injection timing A _INJ 2 of the ignition assist fuel based on the engine operating state, and the target ignition assist fuel target Any timing in the vicinity of the injection timing A _INJ 2 (for example, if the target injection timing A _INJ 2 of the ignition assist fuel is 15 [deg. BTDC], about 18 [deg. BTDC] to 10 [deg. BTDC]) Is set.

In addition to the target values such as the target injection timing A _INJ 1 of the main fuel, the electronic control unit 200 separates the target intake air exhaust valve targets such as the target intake air temperature, the target intake air pressure, and the target intake valve closing timing separately from this flowchart. Valve timing and the like are calculated based on the engine operating state, and various control components are controlled so that the calculated target value is obtained.

  In step S6, the electronic control unit 200 estimates the in-cylinder pressure P and the in-cylinder temperature T at the target intake valve closing timing, that is, the initial in-cylinder state. In the present embodiment, the electronic control unit 200 estimates the initial in-cylinder state using an estimation model for the initial in-cylinder state. The estimation model of the initial in-cylinder state uses the parameters affecting the in-cylinder state such as the intake air amount, the intake air temperature, the intake pressure, and the engine coolant temperature as input values, and the in-cylinder pressure P and the in-cylinder temperature at the target intake valve closing timing It is a physical calculation model for estimating T.

In step S <b> 7, the electronic control unit 200 calculates changes in the in-cylinder pressure P and the in-cylinder temperature T from the target injection timing A _INJ 1 of the main fuel when the ignition assist self-ignition combustion is performed.

  In the present embodiment, the electronic control unit 200 first estimates the transition of the in-cylinder pressure P and the in-cylinder temperature T from the intake valve closing timing using a transition model of the in-cylinder state. The transition model of the in-cylinder state is a physical calculation model for estimating how the in-cylinder state changes from the initial in-cylinder state, and the in-cylinder pressure P and the in-cylinder temperature at the target intake valve closing timing. Assuming that T is an input value and that the in-cylinder pressure P and the in-cylinder temperature T during the compression stroke change in a polytropy, the transition of the in-cylinder pressure P and the in-cylinder temperature T from the target intake valve closing timing is estimated.

  When the ignition assist is performed here, the target ignition is equivalent to the amount of heat generated by the ignition assist with respect to the transition of the in-cylinder pressure P and the in-cylinder temperature T from the intake valve closing timing estimated using the in-cylinder state transition model. Changes in the in-cylinder pressure P and the in-cylinder temperature T from the assist time change.

Therefore, the electronic control unit 200 next starts from the target ignition assist timing A _INJ 2 based on the target injection amount Q _INJ 2 of the ignition assist fuel, the target injection timing A _INJ 2, and the target ignition assist timing IG by the spark plug 16. The changes in the in-cylinder pressure P and the in-cylinder temperature T are corrected, and the changes in the in-cylinder pressure P and the in-cylinder temperature T from the target injection timing A _INJ 1 of the main fuel when ignition-assisted self-ignition combustion is performed. calculate.

In step S8, the electronic control unit 200 uses the transition of the in-cylinder pressure P and the in-cylinder temperature T from the target injection timing A _INJ 1 of the main fuel when performing the ignition assist self-ignition combustion, and integrates Livengood-Wu. From the following equation (1) based on the equation, the expected autoignition timing of the premixed gas [deg. CA] is calculated.

  In the equation (1), τ is the time until the fuel injected into the combustion chamber 11 reaches self-ignition (hereinafter referred to as “ignition delay time”). P is the cylinder pressure, T is the cylinder temperature, φ is the equivalence ratio, ON is the octane number, RES is the inert gas concentration, E is the activation energy, and R is the general gas constant. A, α, β, γ, and δ (A, α, β, δ> 0, γ <0) are identification constants, respectively. In this embodiment, the value of the octane number ON is set based on the detection value of the fuel property sensor 221, and the value of the inert gas concentration is set based on the detection value of the EGR rate and the humidity sensor 220.

In equation (1), when the reciprocal (1 / τ) of the ignition delay time after fuel injection is integrated over time, the time te at which the integrated value is 1 becomes the ignition delay time τ. Therefore, when the reciprocal (1 / τ) of the ignition delay time at the in-cylinder pressure P and the in-cylinder temperature T is integrated over time from the main fuel injection timing A _INJ 1, this corresponds to the time te when the integrated value becomes 1. The time when the crank angle amount is added to the injection timing of the main fuel is the expected self-ignition timing of the premixed gas.

  In step S9, the electronic control unit 200 refers to a map created in advance by experiments or the like, and based on the engine operating state, the target self-ignition timing [deg. CA] is calculated.

  In step S10, the electronic control unit 200 shifts the predicted self-ignition timing relative to the target self-ignition timing toward the advance side (hereinafter referred to as “advance angle shift amount”) Tiga (= target self-ignition timing−expected self-ignition timing). ) [Deg. CA] is greater than a predetermined first threshold value. If the advance angle shift amount Tiga is larger than the first threshold value, the electronic control unit 200 proceeds to the process of step S11 in order to delay the predicted self-ignition timing to the target self-ignition timing. On the other hand, if the advance angle shift amount Tiga is equal to or smaller than the first threshold value, the electronic control unit 200 proceeds to the process of step S15.

In step S11, the electronic control unit 200 determines the ignition assist fuel injection ratio R and the ignition assist fuel target injection timing A _INJ based on the advance angle shift amount Tiga so that the predicted self-ignition timing becomes the target self-ignition timing. 2 and the target ignition assist timing IG are corrected.

Specifically, the electronic control unit 200 refers to the table of FIG. 10 and, based on the advance angle shift amount Tiga, the correction coefficient α by which the injection ratio R of the ignition assist fuel is multiplied, and the target injection timing A _INJ of the ignition assist fuel. 2 and the retardation correction amount β [deg. CA]. As shown in the table of FIG. 10, the correction coefficient becomes smaller than 1 as the advance angle shift amount Tiga becomes larger than the first threshold value. This is because the amount of heat generated when the ignition assist fuel is burned needs to be reduced to retard the self-ignition timing as the advance angle shift amount Tiga increases. The retardation correction amount becomes 0 until the correction coefficient becomes 0, and after the correction coefficient becomes 0, it increases as the advance deviation amount Tiga increases.

Then, the electronic control unit 200 calculates a correction injection ratio R ′ of the ignition assist fuel by multiplying the injection ratio R of the ignition assist fuel by the correction coefficient α. Further, the target injection timing A _INJ 2 of the ignition assist fuel and the target ignition assist timing IG plus the retardation correction amount β are respectively added to the corrected target injection timing A _INJ 2 ′ of the ignition assist fuel and the corrected target ignition assist timing. Calculate as IG '.

  When the predicted self-ignition timing is advanced from the target self-ignition timing as described above, basically, the predicted self-ignition timing is controlled to the target self-ignition timing by reducing the ignition assist fuel. Thereby, since the amount of fuel consumed by flame propagation combustion can be reduced, deterioration of exhaust emission can be suppressed.

In step S12, the electronic control unit 200 calculates the corrected target injection amount Q _INJ 2 ′ of the ignition assist fuel by multiplying the total fuel injection amount Q _INJ by the corrected injection ratio R ′ of the ignition assist fuel, and also calculates the total fuel. corrected target injection amount of the ignition-assisted fuel from the injection quantity _{Q INJ Q INJ} 2 'by subtracting the correction target injection quantity _{Q INJ} 1 of the main fuel' is calculated.

In step S13, the electronic control unit 200 refers to the map of FIG. 11 and calculates a target ozone supply amount Q _OZN based on the engine speed and the corrected target injection amount Q _INJ 1 ′ of the main fuel. As shown in the map of FIG. 11, the target ozone supply amount Q _OZN increases as the corrected target injection amount Q _INJ 1 ′ of the main fuel increases, and decreases as the engine speed increases. In this way, by basically setting the target ozone supply amount Q _OZN according to the corrected target injection amount Q _INJ 1 ′ of the main fuel, that is, the fuel amount contributing to the compression ignition combustion, stepwise with a desired time difference. Compressive self-ignition combustion can occur. As a result, when the predicted self-ignition timing is advanced from the target self-ignition timing, it is possible to suppress the deterioration of combustion noise. Further, when the predicted self-ignition timing is retarded from the target self-ignition timing, it is possible to suppress a decrease in output and a deterioration in exhaust emission.

In step S14, the electronic control unit 200 controls the discharge plug 81 so that the ozone supply amount into the combustion chamber 11 becomes the target ozone supply amount Q _OZN . The electronic control unit 200 is' injected, corrected target injection timing _{A INJ} 2 of assisting ignition fuel 'corrected target injection amount _{Q INJ} 1 to the target injection timing _{A INJ} 1 of the main fuel correction target injection quantity _{Q INJ} 2 to' Is ignited at the corrected target ignition assist timing IG 'to perform ignition assist self-ignition combustion.

  In step S15, the electronic control unit 200 shifts the predicted self-ignition timing relative to the target self-ignition timing toward the retarded side (hereinafter referred to as “retard angle shift amount”) Tigr (= expected self-ignition timing−target self-ignition timing). ) [Deg. CA] is greater than a predetermined second threshold value. In the present embodiment, the first threshold value and the second threshold value are the same value, but may be different values. If the retard amount Tigr is larger than the second threshold, the electronic control unit 200 proceeds to the process of step S16 in order to advance the predicted self-ignition timing to the target self-ignition timing. On the other hand, if the retardation shift amount Tigr is equal to or smaller than the second threshold, the electronic control unit 200 proceeds to the process of step S17.

In step S16, the electronic control unit 200 determines the ignition assist fuel injection ratio R and the ignition assist fuel target injection timing A _INJ 2 based on the retarded shift amount Tigr so that the self-ignition timing becomes the target self-ignition timing. And the target ignition assist timing IG are corrected.

Specifically, the electronic control unit 200 refers to the table of FIG. 12, and based on the retardation shift amount Tigr, the correction coefficient α by which the injection ratio of the ignition assist fuel is multiplied, and the target injection timing A _INJ 2 of the ignition assist fuel. , And an advance correction amount γ [deg. CA]. As shown in the table of FIG. 12, the advance correction amount γ increases as the retardation deviation amount Tigr increases from the second threshold, and becomes constant when the retardation deviation amount Tigr increases to a certain value. This is because if the target injection timing A _INJ 2 of the ignition assist fuel and the target ignition assist timing IG are advanced too much, the ignition assist fuel spreads too much and a rich mixture with a desired equivalent ratio can be formed around the spark plug. This is because the ignition assist self-ignition combustion cannot be performed. The correction coefficient α is set to 1 until the retardation deviation amount Tigr increases to a certain value, and thereafter becomes larger than 1 as the retardation deviation amount Tigr increases.

Then, the electronic control unit 200 calculates a correction injection ratio R ′ of the ignition assist fuel by multiplying the injection ratio R of the ignition assist fuel by the correction coefficient α. Also, the ignition assist fuel target injection timing A _INJ 2 and the target ignition assist timing IG plus the advance correction amount γ are respectively added to the ignition assist fuel corrected target injection timing A _INJ 2 ′ and the corrected target ignition assist timing. Calculate as IG '.

In step S17, the electronic control unit 200 calculates a target ozone supply amount Q _OZN based on the engine speed and the target injection amount Q _INJ 1 of the main fuel with reference to the map of FIG.

In step S18, the electronic control unit 200 controls the discharge plug 81 so that the ozone supply amount into the combustion chamber 11 becomes the target ozone supply amount Q _OZN . Further, the electronic control unit 200 injects the target injection amount Q _INJ 1 at the target injection timing A _INJ 1 of the main fuel, and injects the target injection amount Q _INJ 2 at the target injection timing A _INJ 2 of the ignition assist fuel and the target ignition. Ignition is performed at the assist timing IG to perform ignition assist self-ignition combustion.

  According to this embodiment described above, the engine body 1, the fuel injection valve 20 for directly injecting fuel into the combustion chamber 11 of the engine body 1, and the spark plug 16 arranged so as to face the combustion chamber 11. And an electronic control unit 200 that controls the internal combustion engine 100 including a discharge plug 81 by means of an ozone supply device for supplying ozone directly or indirectly to the combustion chamber 11 so that a concentration difference occurs in the combustion chamber. The control device) causes a part of the fuel to propagate through flame by the spark plug 16 and uses the heat generated at that time to cause the remaining fuel to undergo premixed compression self-ignition combustion. As described above, the combustion control unit that controls the injection amount and injection timing of the fuel injection valve 20 and the ignition timing of the spark plug 16 and the ozone supply amount to the combustion chamber 11 by the ozone supply device are controlled. Comprising an ozone supply amount control section that, the. The combustion control unit controls the injection amount and injection timing of the fuel injection valve 20 and the ignition timing of the spark plug 16 so that the expected self-ignition timing when the ignition assist self-ignition combustion is performed becomes the target self-ignition timing. The ozone supply amount control unit is configured to control the ozone supply amount based on the amount of remaining fuel to be premixed compression self-ignition combustion.

  Therefore, even if the compression auto-ignition timing of the premixed gas is shifted from the target auto-ignition timing due to changes in the outside temperature, the expected auto-ignition timing is the target auto-ignition timing. Thus, since the injection amount and injection timing of the fuel injection valve 20 and the ignition timing of the spark plug 16 are controlled, the compression auto-ignition timing of the premixed gas can be accurately controlled to the target auto-ignition timing. The amount of ozone supply is controlled based on the amount of remaining fuel to be premixed compression autoignition combustion, that is, the main fuel that contributes to premixed compression autoignition combustion. The time of heat generation can be dispersed by causing a time difference.

  The embodiment of the present invention has been described above. However, the above embodiment only shows a part of application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. Absent.

For example, in the above-described embodiment, ozone is supplied so that a concentration difference is generated in the combustion chamber 11 in the entire region within the self-ignition region RR, thereby providing a time difference to cause compression auto-ignition combustion in stages. Combustion noise was suppressed. However, when the engine load is less than the predetermined load, that is, when the total fuel injection amount Q _INJ is less than the predetermined amount, even if the total fuel injection amount Q _INJ is _subjected to compression auto-ignition combustion at a time, the total amount is small. , Combustion noise may not be a problem. In such a case, ozone is supplied so that a concentration difference is generated in the combustion chamber 11 when the engine load is equal to or higher than the predetermined load, and supply of ozone is stopped when the engine load is lower than the predetermined load. good.

DESCRIPTION OF SYMBOLS 1 Engine body 11 Combustion chamber 16 Spark plug 20 Fuel injection valve 81 Discharge plug (ozone supply device)
100 Internal combustion engine 200 Electronic control unit (control device)

Claims (1)

The engine body,
A fuel injection valve for directly injecting fuel into the combustion chamber of the engine body;
A spark plug disposed to face the combustion chamber;
An ozone supply device for supplying ozone directly or indirectly to the combustion chamber so that a concentration difference occurs in the combustion chamber;
An internal combustion engine control device for controlling an internal combustion engine comprising:
The fuel injection is performed so that ignition-assisted self-ignition combustion is caused in the combustion chamber in which a part of the fuel is flame-propagated and combusted by the spark plug and the remaining fuel is premixed compression self-ignition combustion using the heat generated at that time. A combustion control unit for controlling the injection amount and injection timing of the valve and the ignition timing of the spark plug;
An ozone supply amount control unit for controlling the ozone supply amount to the combustion chamber by the ozone supply device;
With
The combustion control unit
Controlling the injection amount and the injection timing of the fuel injection valve and the ignition timing of the spark plug so that the expected self-ignition timing when the ignition assist self-ignition combustion is performed becomes the target self-ignition timing;
The ozone supply amount control unit
Controlling the amount of ozone supply based on the amount of the remaining fuel to be premixed compression auto-ignition combustion;
Control device for internal combustion engine.

Images