JP4098684B2 - Control device for compression ignition internal combustion engine - Google Patents

Description

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

  As an ignition method for internal combustion engines, a compression ignition method in which fuel (light oil) is injected directly into air that has been heated to high temperature by high compression, such as diesel engines that use light oil as fuel, and gasoline is used as fuel. There are two spark ignition methods in the engine, and the current ignition method is almost determined by the fuel. In addition, recently, attempts have been made to self-ignite by supplying an air-fuel mixture obtained by sufficiently mixing various fuels such as gasoline and light oil with air at high temperature and pressure.

  In such an engine, the ignition starts in the entire combustion chamber and reacts at the same time. Therefore, the combustion starts with a low-temperature oxidation reaction, and the combustion temperature can be made relatively low so that the emission of nitrogen oxides is reduced. In addition to being able to reduce, the compression ratio can be increased from the spark ignition engine, and the fuel efficiency can be improved. This type of engine is called a compression ignition engine or a premixed compression ignition engine.

The problem with this compression engine (premixed compression ignition engine) is that the ignition delay increases as the load decreases, eventually leading to misfire. Conversely, pre-ignition occurs as the load increases. Knocking occurs. As a countermeasure, it is known that it is effective to increase the temperature of the air-fuel mixture in order to promote ignition, and while introducing high-temperature EGR gas to promote ignition, the amount of EGR gas is determined according to the load. It is known to control. (For example, refer to Patent Document 1).
Japanese Patent Laid-Open No. 11-132066

  In this prior art, two exhaust valves are provided per cylinder, the first exhaust valve is opened in the exhaust stroke, while the second exhaust valve is opened in both the exhaust stroke and the intake stroke. An independent second exhaust passage is connected to the two exhaust valves, and an open / close valve is provided in the second exhaust passage. At the time of partial load, the on-off valve is opened, exhaust gas is introduced from the second exhaust passage into the combustion chamber in the intake stroke, and the intake valve is opened to stratify with the introduced fresh air (air mixture). While compression ignition combustion is performed above, the open / close valve is closed to suppress the introduction of exhaust gas at full load, and the air-fuel mixture is ignited by spark ignition.

  In the above-described prior art, since the intake valve and the exhaust valve are simultaneously opened during the intake stroke, exhaust gas and air-fuel mixture or air flow into the combustion chamber at the same time. As a result, compression ignition can be performed as expected at low loads when the amount of air-fuel mixture required for combustion is low, but as the amount of air-fuel mixture or air increases as the load increases, the amount of exhaust gas increases. There is an inconvenience that the amount is insufficient and the air-fuel mixture cannot be raised to a temperature required for compression ignition, and therefore compression ignition (self-ignition) cannot be sufficiently achieved in the planned operation region.

  Therefore, the object of the present invention is to solve the above-mentioned problems, and to secure the necessary amount of exhaust gas even when the amount of air-fuel mixture or air increases as the load increases, thereby improving the ignition performance and enabling compression ignition An object of the present invention is to provide a control apparatus for a compression ignition internal combustion engine that expands the operating range.

In order to solve the above object, according to claim 1, in a control apparatus for a compression ignition internal combustion engine, an exhaust pressure variable member disposed in an exhaust system of the internal combustion engine and capable of changing an exhaust pressure, and the internal combustion engine Exhaust pressure variable member control means for controlling the operation of the exhaust pressure variable member according to the engine load, a variable valve mechanism capable of opening and closing an intake valve and an exhaust valve of the internal combustion engine at an arbitrary timing, and the variable motion Variable valve mechanism control means for controlling the operation of the valve mechanism, wherein the variable valve mechanism control means opens the intake valve for a predetermined period to introduce intake air into the combustion chamber, and the exhaust valve Controls the operation of the variable valve mechanism so that the exhaust valve is opened in response to closing of the intake valve and introduces exhaust gas into the combustion chamber, and the exhaust pressure variable member control means controls the internal combustion engine. Load So that the exhaust pressure as it pressurization increases, and as configured to control the operation of the exhaust pressure variable member. Further, in the control device for the compression ignition internal combustion engine according to claim 2, the variable valve mechanism control means is configured to change the closing timing of the intake valve as the load of the internal combustion engine increases.

In the control apparatus for a compression ignition internal combustion engine according to claim 3 , the internal combustion engine includes a plurality of cylinders, and the exhaust pressure variable member is arranged at an exhaust system collection portion of the plurality of cylinders. did.

In the control apparatus for the compression ignition internal combustion engine according to claim 4 , the exhaust pressure variable member is configured to be at least one of a valve and a variable nozzle vane of the exhaust gas turbine supercharger.

In the control apparatus for a compression ignition internal combustion engine according to claim 5 , the internal combustion engine is further configured to include additional fuel injection execution means for executing additional fuel injection.

In the control apparatus for the compression ignition internal combustion engine according to the first aspect, the variable valve mechanism control means for controlling the operation of the variable valve mechanism that can open and close the intake valve and the exhaust valve at an arbitrary timing includes: is introduced into the combustion chamber intake air by a predetermined period of time open, the exhaust valve for controlling operation thereof so as to introduce into the combustion chamber exhaust gas by opening in response to the closing of the intake valve, an exhaust pressure variable Since the member control means is configured to control the operation of the exhaust pressure variable member so that the exhaust pressure increases as the load of the internal combustion engine increases , the intake valve and the exhaust valve are simultaneously opened during the intake stroke. Therefore, it is possible to avoid the exhaust gas and the air-fuel mixture or air from flowing into the combustion chamber at the same time. Therefore, the necessary amount of exhaust gas can be ensured even when the amount of air-fuel mixture or air that increases as the load increases.

That is, by opening the exhaust valve in response to closing of the intake valves, the amount of exhaust gas to be introduced is reduced, the operation of the exhaust pressure variable member so as to increase the exhaust pressure as the load increases By controlling the above, it is possible to secure a necessary amount of introduced exhaust gas and to raise the temperature of the air-fuel mixture to a temperature required for compression ignition. Therefore, a necessary amount of exhaust gas can be ensured even when the amount of air-fuel mixture or air increases as the load increases, so that the ignition performance can be improved and the operating range in which compression ignition is possible is expanded. be able to.

As used herein, “so that the exhaust valve is opened in response to the closing of the intake valve and the exhaust gas is introduced into the combustion chamber” means that the exhaust gas and the air-fuel mixture or air are simultaneously mixed. This means that the intake valve and the exhaust valve are not opened at the same time so as to avoid entering the combustion chamber, and therefore the intake valve closing and the exhaust valve opening do not overlap at all. Not a thing. That is, if the exhaust gas and the air-fuel mixture or air can be prevented from flowing into the combustion chamber at the same time, this means that the intake valve closing and the exhaust valve opening may slightly overlap. In the control device for the compression ignition internal combustion engine according to claim 2, the variable valve mechanism control means is configured to change the valve closing timing of the intake valve as the load of the internal combustion engine increases. The obtained effect can be obtained more effectively.

In the control apparatus for the compression ignition internal combustion engine according to claim 3 , since the exhaust pressure variable member is arranged in the exhaust system collecting portion of the plurality of cylinders, the configuration of the prior art in which an open / close valve is provided for each cylinder. The exhaust pressure can be changed while the configuration is simpler than that of the engine, and for example, the exhaust pressure can be increased as the load increases, thereby ensuring the amount of exhaust gas more reliably. .

In the control apparatus for a compression ignition internal combustion engine according to claim 4, exhaust pressure variable member, Owing to this arrangement is at least one of the variable nozzle of the valve and the supercharger, that described in claim 3 and Similar effects can be obtained.

In the control apparatus for the compression ignition internal combustion engine according to claim 5 , the internal combustion engine is further configured to include additional fuel injection execution means for executing additional fuel injection. Combustion with exhaust gas can further increase the temperature of the air-fuel mixture, and the temperature can be raised more reliably to the temperature required for compression ignition, shortening the opening time of the exhaust valve that introduces exhaust gas It becomes possible to do. Therefore, the amount of air or air-fuel mixture can be increased by extending the valve opening period of the intake valve for introducing air or air-fuel mixture, and the compression ignition operation range is expanded. It should be noted that additional fuel injection execution conditions may be set according to the load and exhaust temperature.

  The best mode for carrying out a control apparatus for a compression ignition internal combustion engine according to the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram generally showing a control apparatus for a compression ignition internal combustion engine according to a first embodiment of the present invention.

  In FIG. 1, reference numeral 10 indicates a four-cylinder four-cycle internal combustion engine (hereinafter referred to as “engine”) using gasoline as fuel. In the engine 10, air drawn from an air cleaner (not shown) and passing through the intake pipe 12 is adjusted in flow rate by the throttle valve 14, flows through the intake manifold 16, and burns when the two intake valves 18 are opened. Flows into the chamber (not shown).

  An injector 20 is disposed in the vicinity of the intake valve 18. Gasoline fuel stored in a fuel tank (not shown) is pumped to the injector 20 through a fuel supply pipe (not shown) and connected to an ECU (electronic control unit) 24 through a drive circuit 22. When a drive signal indicating the valve opening time is supplied from the ECU 24 to the drive circuit 22, the injector 20 opens and injects gasoline fuel corresponding to the valve opening time into the combustion chamber. The injected gasoline fuel is mixed with the inflowing air to form an air-fuel mixture. Thus, the engine 10 is configured as an in-cylinder injection type engine.

  Two spark plugs 26 are arranged on the left and right of the injector 20. The spark plug 26 is connected to the ECU 24 via an ignition device 30 such as an igniter. When an ignition signal is supplied from the ECU 24 to the ignition device 30, a spark discharge is generated between the electrodes facing the combustion chamber to ignite the air-fuel mixture. And burn. As will be described later, the air-fuel mixture is also combusted by compression ignition. That is, the engine 10 is configured as a compression ignition engine (internal combustion engine) that switches between pre-combustion ignition combustion in which an air-fuel mixture is combusted by compression ignition and spark ignition combustion in which spark ignition is combusted in accordance with an operating state. The

  Gas (exhaust gas) generated by combustion flows to the exhaust manifold 34 when the two exhaust valves 32 are opened. The exhaust manifold 34 gathers downstream to form an exhaust system gathering portion 34a, to which an exhaust pipe 36 is connected. The exhaust gas flows through the exhaust manifold 34, then flows through the exhaust pipe 36, and is further released to the atmosphere outside the engine.

  A crank angle sensor (shown as “ENG rotational speed” in the figure) 40 is disposed in the vicinity of the crankshaft or camshaft (both not shown) of the engine 10, and a cylinder discrimination signal and TDC (top dead center) of each cylinder. ) Or a TDC signal indicating a crank angle in the vicinity thereof, and a crank angle signal obtained by subdividing the TDC signal. Those outputs are input to the ECU 24.

  The ECU 24 includes a microcomputer and includes a CPU, ROM, RAM, A / D conversion circuit, input / output circuit, and counter. The ECU 24 counts the crank angle signal in the input signal and calculates (detects) the engine speed (ENG speed) NE.

  An accelerator pedal (not shown) is arranged on the floor of a driver's seat (not shown) of the vehicle on which the engine 10 is mounted, and an accelerator opening sensor ("Accelerator opening" in the figure) 42) is provided and outputs a signal corresponding to the accelerator opening ACC indicating the amount of depression of the driver's accelerator pedal. The output is also input to the ECU 24.

  The throttle valve 14 is mechanically disconnected from the accelerator pedal and connected to an actuator (such as a stepping motor) 44. The actuator 44 is connected to the ECU 24. The ECU 24 drives the actuator 44 from the accelerator opening ACC detected through the accelerator opening sensor 42 and controls the opening TH of the throttle valve 14. Thus, the operation of the throttle valve 14 is controlled by the DBW method.

  A rotation angle sensor 46 such as a rotary encoder is connected to the actuator 44, and a signal corresponding to the throttle opening TH is output through the rotation angle of the actuator 44 and sent to the ECU 24.

  An air flow meter 50 is disposed near the air cleaner of the engine 10 and outputs a signal corresponding to the intake air amount Q indicating the engine load. A temperature sensor 52 is disposed in the exhaust pipe 36 and outputs a signal corresponding to the exhaust temperature TEX. Further, a water temperature sensor (not shown) is arranged in a cooling water passage (not shown) of the engine 10 to output a signal corresponding to the engine cooling water temperature TW, and another temperature sensor is provided near the air flow meter 50. (Not shown) is arranged and outputs a signal corresponding to the temperature TA of the intake air. The outputs of these sensor groups are also input to the ECU 24.

  The intake valve 18 and the exhaust valve 32 are connected to a variable valve mechanism 54. The variable valve mechanism 54 includes electromagnetic solenoids arranged near the shafts of the four valves, and when energized, drives the shaft to open or close the intake valve 18 or the exhaust valve 32.

  Further, in the exhaust system of the engine 10, an exhaust pipe opening / closing valve whose exhaust pressure (exhaust gas pressure) can be changed is provided in the exhaust system collecting portion 34a of four (plural) cylinders, more specifically, in the exhaust pipe 36 connected thereto. (Exhaust pressure variable member) 56 is arranged. The exhaust pipe opening / closing valve 56 is a butterfly valve similar to the throttle valve 14, and is connected to the ECU 24 via the drive circuit 60. The ECU 24 controls its operation (valve opening) in accordance with the detected engine load, that is, the intake air amount Q, as will be described later.

  Next, the operation of the control apparatus for the compression ignition internal combustion engine according to the first embodiment will be described.

  FIG. 2 is a flowchart showing the operation. The illustrated program is started every predetermined time, for example, 10 msec.

  Explained below, in S10, the required load (required torque) PMECMD [N · m] of the engine 10 is calculated from the accelerator opening ACC and the engine speed NE. This is done by searching map data whose characteristics are shown in FIG.

  Next, in S12, the output of the above-described sensor group excluding the crank angle sensor 40 is read, and engine operating parameters such as the intake air amount Q, the exhaust temperature TEX, the throttle opening TH, and the engine coolant temperature TW are detected.

  Next, in S14, it is determined whether or not the operation of the engine 10 is in the premixed compression ignition (HCCI) operation region. This is performed by searching the map data showing the characteristics in FIG. 4 from the calculated required load PMECMD and the engine speed NE. In the premixed compression ignition (HCCI) operation region, as shown in the figure, the required load PMECMD and the engine speed NE are extremely small, such as an idle region (very low load region), and the required load PMECMD and the engine rotational speed NE are high. Regions other than the region (high load region), in other words, low load and medium load regions.

  When the result in S14 is affirmative, the program proceeds to S16, and the EGR amount (exhaust gas amount) required in the operating state is calculated from the similarly calculated required load PMECMD and engine speed NE. As will be described later, EGR is EGR by so-called internal EGR.

  Next, the process proceeds to S18, and the opening and closing timing (valve timing and lift amount) of the intake valve 18 and the exhaust valve 32 are determined from the similarly calculated required load PMECMD and the engine speed NE.

  FIG. 5 is an explanatory diagram for explaining the characteristics of the opening and closing timings (valve timing and lift amount) determined in S18. FIG. 4A shows the characteristics when the load is small (the intake air amount Q is small), and FIG. 4B shows the characteristics when the load is increased (the intake air amount Q is increased).

  Referring to the figure, in the exhaust stroke, the exhaust valve 32 is opened, and the opening and closing timing is determined so that the exhaust gas generated by the combustion is exhausted to the exhaust manifold 34.

  In the subsequent intake stroke, the intake valve 18 opens for a predetermined period to introduce intake air into the combustion chamber, and the exhaust valve 32 opens in response to the closing of the intake valve 18 to introduce exhaust gas into the combustion chamber. To control. That is, in the intake stroke, first, the intake valve 18 is opened, and the intake air is introduced into the combustion chamber.

  At this time, the amount of air required for combustion differs depending on the required load PMECMD and the engine speed NE. More precisely, the required air amount increases as the required load PMECMD and the engine speed NE increase. As shown in comparison with FIGS. 1A and 1B in accordance with NE, the closing timing of the intake valve 18 is changed, and the closing timing is delayed (in crank angle) as the intake air amount increases. If so, it is determined to extend the valve opening period (predetermined period).

  Therefore, the above-mentioned “predetermined period” is not a fixed value but a period sufficient to introduce an air amount necessary for combustion and means a variable value. The engine 10 according to this embodiment is an in-cylinder injection engine. Therefore, the engine 10 is performed according to the amount of air. However, in the case of an engine in which fuel is injected into the intake port, the intake air is determined according to the amount of air-fuel mixture. The valve closing timing of the valve 18 is determined.

  Next, almost simultaneously with the closing timing of the intake valve 18, the exhaust valve 32 is opened, and after the amount of exhaust gas calculated in S16 is introduced into the combustion chamber, the exhaust valve 32 is closed and the process proceeds to the compression stroke. .

  Thus, since the intake valve 18 and the exhaust valve 32 are not simultaneously opened during the intake stroke, it is possible to avoid exhaust gas and air from flowing into the combustion chamber at the same time. Therefore, the necessary amount of exhaust gas can be secured even when the necessary amount of air increases. More specifically, by opening the exhaust valve 32 in response to the closing of the intake valve 18, the opening time of the exhaust valve 32 is shortened, and the amount of exhaust gas to be introduced is calculated in S16. As described later, the operation of the exhaust pressure variable member (exhaust pipe opening / closing valve) 56 is controlled so as to increase the exhaust pressure as the load increases, as described later. The amount was secured.

  Here, “exhaust valve 32 is opened in response to closing of intake valve 18 to introduce exhaust gas into the combustion chamber”, as is clear from the above, exhaust gas and air simultaneously flow into the combustion chamber. This means that the intake valve 18 and the exhaust valve 32 are not opened at the same time so that the intake valve 18 and the exhaust valve 22 are not opened at the same time. Not a thing. That is, it is only necessary to avoid the exhaust gas and air from flowing into the combustion chamber at the same time, and there is no problem even if the intake valve 18 and the exhaust valve 32 are slightly overlapped.

  Returning to the description of the flow chart of FIG. 2, the process then proceeds to S20, in which the valve opening degree of the exhaust pipe opening / closing valve (exhaust pressure variable member) 56 is determined according to the required load PMECMD and the engine speed NE. As described above, as the engine load increases, the valve opening period of the exhaust valve 32 is shortened. Therefore, the opening degree of the exhaust pipe opening / closing valve 56 depends on the required load PMECMD and the engine speed NE, more specifically, As the required load PMECMD increases, in other words, as the load of the engine 10 increases, the exhaust pressure (exhaust gas pressure) is increased by decreasing (determining the valve closing direction), and the exhaust valve 32 is opened. The amount of exhaust gas (EGR) to be introduced is ensured by compensating for the shortening.

  Since the intake air amount Q is a parameter indicating the engine load, the valve opening degree is determined by using the intake air amount Q and the engine speed (or only the intake air amount Q) instead of the required load PMECMD and the engine speed NE. May be determined. Furthermore, since the exhaust temperature TEX is also proportional to the engine load, the valve opening degree may be determined using the exhaust temperature TEX and the engine speed NE (or only the exhaust temperature TEX).

  Next, the routine proceeds to S22, in which spark ignition is turned off, that is, ignition through the spark plug 26 is not performed, the throttle opening TH is fully opened, and the intake and exhaust valves 18, 32 are opened and closed at the timing determined in S18. Thus, the operation of the variable valve mechanism 54 is controlled. Further, the operation of the exhaust pipe opening / closing valve 56 is controlled via the drive circuit 60 so that the opening degree determined in S20 is obtained.

  Further, fuel injection amount control is also executed. Specifically, the fuel injection amount is determined by searching map data set in advance according to the required load PMECMD and the engine speed NE, and most of the determined fuel injection amount is changed from the intake stroke to the compression stroke. The remaining portion is injected in the next expansion stroke (additional fuel injection is performed). As a result, the temperature of the air-fuel mixture can be further increased by burning the additionally injected fuel with the exhaust gas, and the in-cylinder gas temperature can be more reliably increased to the temperature required for compression ignition. Can do. Additional fuel injection execution conditions may be set according to the load and exhaust temperature. Further, the additional fuel injection is configured to be executed in the expansion stroke. However, in the port injection engine, additional fuel injection cannot be performed in the expansion stroke. In this case, after the exhaust stroke at a timing different from the main injection, To be executed or before the main injection.

  On the other hand, when the result in S14 is negative, the program proceeds to S24, in which the throttle opening TH is controlled according to the required load PMECMD. Further, map data set in advance according to the required load PMECMD and the engine speed NE is searched to determine the ignition timing, and spark discharge is performed at the determined ignition timing to ignite the air-fuel mixture.

  Further, the fuel injection amount is determined and fuel injection is executed in the same manner as described in S22 (however, in this case, all of the determined fuel injection amount is injected from the intake stroke to the compression stroke, and additional fuel injection is performed). Do not run). At the same time, the air-fuel ratio (A / F) is also controlled. Since the premixed compression ignition is not executed, the exhaust pipe opening / closing valve 56 is fully opened.

  Since this embodiment is configured as described above, the intake valve 18 and the exhaust valve 32 are not simultaneously opened during the intake stroke, and the exhaust gas and air can be prevented from flowing into the combustion chamber at the same time. . Therefore, the necessary amount of exhaust gas can be ensured even when the amount of air-fuel mixture or air that increases as the load increases.

  That is, by opening the exhaust valve 32 in response to the closing of the intake valve 18, the amount of exhaust gas to be introduced decreases, but the exhaust pressure of the exhaust pipe opening / closing valve 56 increases as the load increases. By controlling so as to increase, the necessary amount of exhaust gas introduced can be secured, and the in-cylinder gas temperature can be raised to the temperature required for compression ignition. Therefore, the required amount of exhaust gas can be ensured even when the required amount of air-fuel mixture or air increases as the load increases, so that the ignition performance can be improved and the operating range in which compression ignition can be performed. Can be enlarged. Further, the exhaust pipe opening / closing valve 56 is also simpler than the configuration of the prior art in which an opening / closing valve is provided for each cylinder.

  The above will be described with reference to FIGS. FIG. 6 is an explanatory view showing the operation of the apparatus according to this embodiment, and FIG. 7 is an explanatory view showing the operation of the apparatus according to the prior art.

  In the case of the prior art shown in FIG. 7, the amount of EGR (exhaust gas) to be introduced decreases as described above as the required amount of air increases as the load increases as shown in the upper diagram. As shown in the figure below, the actual temperature in the cylinder cannot satisfy the self-ignitable temperature at a certain load (point a in the figure), and compression ignition is impossible even in the operation region where compression ignition is scheduled.

  On the other hand, in the case of the apparatus according to this embodiment shown in FIG. 6, by driving the exhaust pipe opening / closing valve 56 from the point a in the valve closing direction as shown in the upper figure, as shown in the middle figure, The amount of EGR to be introduced can be ensured as compared with the prior art indicated by the broken line, and therefore, the operation region where compression ignition is possible can be expanded as shown in the figure below. More precisely, the compression ignition can be reliably realized in the range where the compression ignition shown in FIG. 4 is scheduled.

  Next, a control apparatus for a compression ignition internal combustion engine according to a second embodiment of the present invention will be described.

  FIG. 8 is a schematic view similar to FIG. 1 showing the overall control apparatus for a compression ignition internal combustion engine according to the second embodiment.

  The description will be focused on the differences from the first embodiment. In the second embodiment, the exhaust pressure variable member is constituted by the variable nozzle vane 70a1 of the turbine 70a of the exhaust gas turbine supercharger 70. In the second embodiment, an exhaust gas turbine supercharger (hereinafter referred to as “supercharger”) 70 is inserted into the exhaust pipe 36 and the intake pipe 12 and is connected to the turbine 70a. And a compressor 70b that is driven to rotate. The turbine 70a is provided with a variable nozzle vane 70a1.

  The supercharger 70 is connected to the ECU 24. The ECU 24 drives the variable nozzle vane 70a1 by the link via the drive circuit 72 according to the engine load (required load PMECMD or intake air amount Q), the engine speed NE, and the like, and determines the angle of the exhaust gas hitting the blade (not shown). Adjust and maintain turbine speed in the supercharging effective range.

  The compressor 70b rotated by the turbine 70a compresses the air flowing through the intake pipe 12 and introduces it into each cylinder from the intake manifold 16. When the supercharging pressure becomes excessive, the bypass valve (waste gate valve) 76 is opened via the drive circuit 74 and the pressure is lowered.

  The operation of the apparatus according to the second embodiment is the same as that described in the flowchart of FIG. 2 of the first embodiment. However, since the supercharged air is supplied, the valve opening time of the intake valve 18 may be shortened in the characteristics shown in FIG. Since the supercharged air is supplied, the compression ignition operation region can be expanded to a higher load region than in the first implementation. The remaining configuration and effects are not different from those of the first embodiment.

  Since the second embodiment is configured as described above, by controlling the variable nozzle vane 70a1 according to the engine speed NE, the necessary air-fuel mixture or air as the load increases as described in the first embodiment. When the amount of exhaust gas increases, the exhaust pressure can be increased according to the increase in engine load, and the necessary amount of exhaust gas introduced can be ensured.

As described above, in the first and second embodiments of the present invention, compression ignition internal combustion engines, more specifically, combustion by compression ignition combustion and spark ignition in which an air-fuel mixture is combusted by compression ignition according to the operating state. In a control apparatus for a compression ignition internal combustion engine (engine) 10 that switches between spark ignition combustion to be performed, an exhaust pressure variable member (exhaust pipe opening / closing valve 56, variable) disposed in an exhaust system of the internal combustion engine and capable of changing an exhaust pressure. Nozzle vane 70a1), exhaust pressure variable member control means (ECU 24, drive circuits 60, 72) for controlling the operation of the exhaust pressure variable member according to the load of the internal combustion engine, intake valve 18 and exhaust valve of the internal combustion engine And a variable valve mechanism (54) that can freely open and close 32 and variable valve mechanism control means (ECU24) for controlling the operation of the variable valve mechanism. The variable valve mechanism control means opens the intake valve for a predetermined period to introduce intake air into the combustion chamber, and opens the exhaust valve in response to closing of the intake valve to combust the exhaust gas. The exhaust pressure variable member control means controls the operation of the variable valve mechanism so as to be introduced into the chamber, and the exhaust pressure variable member control means adjusts the exhaust pressure so that the exhaust pressure increases as the load of the internal combustion engine increases. The operation of the members is controlled (ECU 24, S16 to S22). Further, the variable valve mechanism control means is configured to change the closing timing of the intake valve (ECU 24, S18, S22) as the load of the internal combustion engine increases.

  The internal combustion engine includes a plurality of (four) cylinders, and the exhaust pressure variable member is disposed in an exhaust system collection portion 34a of the plurality of cylinders, more precisely, an exhaust pipe 36 connected thereto. It was configured as follows.

  Further, the exhaust pressure variable member is configured to be at least one of a valve (exhaust pipe opening / closing valve) 56 and a variable nozzle vane 70a1 of the exhaust gas turbine supercharger 70.

  Further, the internal combustion engine is configured to include additional fuel injection execution means (ECU 24, S22) for executing additional fuel injection.

  In the above description, two intake valves 18 and two exhaust valves 32 are provided.

  Further, the opening and closing characteristics of the intake valve 18 and the exhaust valve 32 shown in FIG. 5 are merely examples, and the present invention is not limited thereto.

  Further, although the embodiment of the present invention has been described by taking a cylinder injection engine as an example, the present invention is applicable even to a port injection engine.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing an overall control apparatus for a compression ignition internal combustion engine according to a first embodiment of the present invention. It is a flowchart explaining operation | movement of the apparatus shown in FIG. 2 is an explanatory graph showing the map data characteristics of the required load (required torque) PMECMD used in the processing of the flow chart of FIG. FIG. 3 is an explanatory graph showing map data characteristics of a premixed compression landing operation region used in the processing of the flow chart of FIG. 2. 2 is an explanatory diagram for explaining characteristics of intake and exhaust valve opening and valve closing timing (valve timing and lift amount) used in the processing of the flow chart of FIG. 2 is an explanatory diagram showing the processing of the flow chart. It is explanatory drawing which shows the process of a prior art as contrasted with FIG. It is the schematic which shows the control apparatus of the compression ignition internal combustion engine which concerns on 2nd Example of this invention generally.

Explanation of symbols

10 Compression ignition internal combustion engine (engine)
18 Intake valve 24 ECU (electronic control unit)
32 Exhaust valve 34 Exhaust manifold (exhaust system)
34a Exhaust system assembly (exhaust system)
54 Variable valve mechanism 56 Exhaust pipe open / close valve (exhaust pressure variable member)
70 Exhaust gas turbine supercharger 70a1 Variable nozzle vane (exhaust pressure variable member)

Claims (5)

In a control apparatus for a compression ignition internal combustion engine, an exhaust pressure variable member disposed in an exhaust system of the internal combustion engine and capable of changing an exhaust pressure, and an exhaust for controlling an operation of the exhaust pressure variable member according to a load of the internal combustion engine A pressure variable member control means; a variable valve mechanism that can open and close the intake valve and the exhaust valve of the internal combustion engine at an arbitrary timing; and a variable valve mechanism control means that controls the operation of the variable valve mechanism. The variable valve mechanism control means opens the intake valve for a predetermined period and introduces intake air into the combustion chamber, and opens the exhaust valve in response to closing of the intake valve to release the exhaust gas. so as to introduce into the combustion chamber, to control the operation of the variable valve mechanism, the exhaust pressure varying member control means, as the exhaust pressure increases as the load of the internal combustion engine is increased, before Control system for a compression ignition internal combustion engine and controls the operation of the exhaust pressure variable member. 2. The control apparatus for a compression ignition internal combustion engine according to claim 1, wherein the variable valve mechanism control means changes the closing timing of the intake valve as the load of the internal combustion engine increases. 3. The control device for a compression ignition internal combustion engine according to claim 1, wherein the internal combustion engine includes a plurality of cylinders, and the exhaust pressure variable member is disposed in an exhaust system collection portion of the plurality of cylinders. . The control apparatus for a compression ignition internal combustion engine according to any one of claims 1 to 3, wherein the exhaust pressure variable member is at least one of a valve and a variable nozzle vane of an exhaust gas turbine supercharger. The control apparatus for a compression ignition internal combustion engine according to any one of claims 1 to 4 , wherein the internal combustion engine further includes additional fuel injection execution means for executing additional fuel injection.