JP2011021483A - Combustion control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a combustion control device for an internal combustion engine suppressing misfire when switching from compression self-ignition combustion to spark ignition combustion. <P>SOLUTION: This combustion control device for the internal combustion engine capable of switching between the spark ignition combustion and the compression self-ignition combustion by internal EGR gas includes a control means 11, which performs control to inject fuel from the closing timing of an exhaust valve through a top dead center in an exhaust stroke until the closing timing EVC of the exhaust valve 122 is shifted to predetermined timing when switching from the compression self-ignition combustion to the spark ignition combustion. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  A gasoline engine that performs compression self-ignition combustion is known in which the opening timing of the intake valve and the closing timing of the exhaust valve are set to minus overlap, and fuel is injected during the minus overlap period (patent) Reference 1).

Japanese Patent Laying-Open No. 2005-220839

  However, in the above-described conventional engine, when switching between compression self-ignition combustion and spark ignition combustion, there is a risk of misfire if the closing timing of the exhaust valve does not shift or the shift is delayed. For example, when switching from compression self-ignition combustion to spark ignition combustion, if the closing timing of the exhaust valve is not retarded, the internal EGR increases and new air decreases, so that there is a problem that rich misfire occurs and spark ignition combustion does not occur.

A problem to be solved by the present invention is to provide a combustion control device for an internal combustion engine that suppresses misfire when switching from compression self-ignition combustion to spark ignition combustion or when switching from spark ignition combustion to compression self-ignition combustion. That is.

The present invention relates to an exhaust valve in compression self-ignition combustion until the transition of the closing timing of the exhaust valve is completed when switching from compression self-ignition combustion to spark ignition combustion or when switching from spark ignition combustion to compression self-ignition combustion. The above-mentioned problem is solved by injecting fuel between the closing time and top dead center.

  According to the present invention, the fuel is injected from the closing timing of the exhaust valve to the top dead center in the compression self-ignition combustion until the transition of the closing timing of the exhaust valve is completed. When switching to spark ignition combustion, compression self-ignition combustion continues even if the exhaust valve closing timing is delayed and the internal EGR increases. Thereby, misfire at the time of switching from compression self-ignition combustion to spark ignition combustion can be suppressed.

1 is a block diagram showing an internal combustion engine to which an embodiment of the present invention is applied. It is a perspective view which shows the variable valve mechanism of the exhaust valve of the internal combustion engine of FIG. It is sectional drawing for the operation | movement of the variable valve mechanism of FIG. 2A (at the time of compression self-ignition combustion). It is sectional drawing for the operation | movement of the variable valve mechanism of FIG. 2A (at the time of spark ignition combustion). 2 is a valve timing diagram showing control during compression self-ignition combustion of the internal combustion engine of FIG. 1. 2 is a valve timing diagram showing control at the time of spark ignition combustion of the internal combustion engine of FIG. 1. 2 is a graph showing control at the time of switching from compression self-ignition combustion to spark ignition combustion of the internal combustion engine of FIG. 1. 2 is a flowchart showing control at the time of switching from compression self-ignition combustion to spark ignition combustion of the internal combustion engine of FIG. 1. 2 is a graph showing control at the time of switching from spark ignition combustion to compression self-ignition combustion of the internal combustion engine of FIG. 1. 2 is a flowchart showing control at the time of switching from spark ignition combustion to compression self-ignition combustion of the internal combustion engine of FIG. 1. 3 is a graph showing the relationship between the closing timing of the exhaust valve and the first fuel injection timing of the internal combustion engine shown in FIG. 1 and the amount of unburned gas discharged.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a gasoline engine EG capable of switching between spark ignition combustion and compression self-ignition combustion to which an embodiment of the present invention is applied. An air filter 112, An air flow meter 113 for detecting the intake air flow rate, a throttle valve 114 for controlling the intake air flow rate, and a collector 115 are provided.

  The throttle valve 114 is provided with an actuator 116 such as a DC motor that adjusts the opening of the throttle valve 114. The throttle valve actuator 116 is based on the drive signal from the engine control unit 11 (corresponding to the control means of the present invention) based on the drive signal so as to achieve the required torque calculated based on the driver's accelerator pedal operation amount and the like. The opening degree of the valve 114 is electronically controlled. In addition, a throttle sensor 116 a that detects the opening of the throttle valve 114 is provided, and the detection signal is output to the engine control unit 1. The throttle sensor 116a can also function as an idle switch.

  The fuel injection valve 118 is provided facing the combustion chamber 123. The fuel injection valve 118 is driven to open by a drive pulse signal set in the engine control unit 11 and directly injects fuel, which is pumped from a fuel pump (not shown) and controlled to a predetermined pressure by a pressure regulator, into the cylinder. In this example, in the compression self-ignition combustion mode, fuel is injected in each of the exhaust stroke and the intake stroke, and in the spark ignition combustion mode, fuel is injected in the intake stroke, the details of which will be described later.

  A space surrounded by the cylinder 119, the crown surface of the piston 120 that reciprocates within the cylinder, and the cylinder head provided with the intake valve 121 and the exhaust valve 122 constitutes a combustion chamber 123. The spark plug 124 is provided facing the combustion chamber 123 of each cylinder, and ignites the intake air-fuel mixture in the spark ignition combustion mode based on the ignition signal from the engine control unit 11. Note that in the case of the compression self-ignition combustion mode, the operation is not performed, and this point will be described later.

  The combustion chamber 123 is provided with a pressure sensor 117 that detects the in-cylinder pressure, and outputs a signal of the detected in-cylinder pressure to the engine control unit 11. The engine control unit 11 executes various controls according to the detected in-cylinder pressure when switching from compression self-ignition combustion to spark ignition combustion and when switching from spark ignition combustion to compression self-ignition combustion. Details of this will be described later.

  On the other hand, the exhaust passage 125 is provided with an air-fuel ratio sensor 126 for detecting an exhaust gas by detecting a specific component in the exhaust gas, for example, oxygen concentration, and thus an air-fuel ratio of the intake air-fuel mixture. Is output. The air-fuel ratio sensor 126 may be an oxygen sensor that performs rich / lean output, or a wide-area air-fuel ratio sensor that linearly detects the air-fuel ratio over a wide area.

  The exhaust passage 125 is provided with an exhaust purification catalyst 127 for purifying the exhaust. The exhaust purification catalyst 127 oxidizes carbon monoxide CO and hydrocarbon HC in the exhaust in the vicinity of stoichiometric (theoretical air-fuel ratio, λ = 1, air weight / fuel weight = 14.7), and nitrogen oxide NOx. It is possible to use a three-way catalyst that can purify the exhaust gas by reducing the above, or an oxidation catalyst that oxidizes carbon monoxide CO and hydrocarbon HC in the exhaust gas.

  On the downstream side of the exhaust purification catalyst 127 in the exhaust passage 125, there is provided an oxygen sensor 128 that detects a specific component in the exhaust, for example, oxygen concentration, and outputs a rich / lean output, and the detection signal is output to the engine control unit 11. The Here, by correcting the air-fuel ratio feedback control based on the detection value of the air-fuel ratio sensor 126 based on the detection value of the oxygen sensor 128, so as to suppress a control error associated with the deterioration of the air-fuel ratio sensor 126 (so-called) Although the downstream oxygen sensor 128 is provided (for the adoption of a double air-fuel ratio sensor system), if it is only necessary to perform air-fuel ratio feedback control based on the detection value of the air-fuel ratio sensor 126, the oxygen sensor 128 is Can be omitted.

  In FIG. 1, reference numeral 129 denotes a muffler.

  The crankshaft 130 of the engine EG is provided with a crank angle sensor 131, and the engine control unit 11 counts a crank unit angle signal output from the crank angle sensor 131 in synchronization with the engine rotation for a predetermined time, or By measuring the cycle of the crank reference angle signal, the engine speed Ne can be detected.

  The cooling jacket 132 of the engine EG is provided with a water temperature sensor 133 facing the cooling jacket, detects the cooling water temperature Tw in the cooling jacket 131, and outputs this to the engine control unit 11.

  Each of the intake valve 121 and the exhaust valve 122 of the engine EG of this example is provided with a variable valve mechanism 60, and the opening / closing timing of the intake valve 121 and the exhaust valve 122 is independently variable by a command signal from the engine control unit 11. It is said that.

  The variable valve mechanism 60 provided in the exhaust valve 122 of the present example is a so-called step switching valve mechanism in which the closing timing EVC of the exhaust valve 122 changes stepwise, and FIG. 2A can be provided in the exhaust valve 122. FIG. 2B is a sectional view showing a switching state of the variable valve mechanism 60 in the compression self-ignition combustion mode, and FIG. 2C is a switching of the variable valve mechanism 60 in the spark ignition combustion mode. It is sectional drawing which shows a state.

  Only the variable valve mechanism 60 provided in the exhaust valve 122 will be described below, but the variable valve mechanism 60 provided in the intake valve 121 can also be provided with the same step-switching variable valve mechanism 60. Instead, a variable valve mechanism that continuously changes the opening / closing timing of the intake valve 121 may be provided.

  The variable valve mechanism 60 of this example is different from the exhaust valve 122 slidably provided in the cylinder head via a valve guide (not shown). The camshaft 601 has two types of first cams having different valve lift and valve timing. 602 and a second cam 603 are provided, and a rocker shaft 604 extending in the arrangement direction of the exhaust valves 122 of the cylinder head is provided therebetween. A first cam 602 is provided at the center of the camshaft 601, and second cams 603 are provided on both sides thereof.

  A rocker arm 605 is swingably provided on the rocker shaft 604, and a first follower 606 and a second follower 607 are connected to the rocker arm 605 between the first cam 602 and the second cam 603 of the camshaft 601. It is provided to correspond to each.

  The rocker shaft 604 is provided with a sub rocker arm 608 that can be coupled to or decoupled from the rocker arm 605. 2A is provided with a lever 610 that operates between the position shown in FIG. 2B and the position shown in FIG. 2C. When hydraulic pressure is not applied by the hydraulic supply system 609, as shown in FIG. 2B. When the lever 610 is retracted by the return spring 611 so that the sub rocker arm 608 and the rocker arm 605 are not coupled, when hydraulic pressure is applied by the hydraulic pressure supply system 609, the lever 610 is shown in FIG. 2C via the hydraulic plunger 612. Then, the lever moves forward, and the sub rocker arm 608 and the rocker arm 605 are coupled.

  That is, according to the variable valve mechanism 60 of the present example, as shown in FIG. 2B, when the hydraulic pressure by the hydraulic pressure supply system 609 is released, the lever 610 moves backward and the rocker arm 605 and the sub-rocker arm 608 are not connected. In the coupled state, the movement of the first cam 602 that contacts the first follower 606 is absorbed by the lost motion mechanism 613, and only the second cam 603 acts on the rocker arm 605. As a result, the exhaust valve 122 operates at the valve lift and valve timing in the compression self-ignition combustion mode according to the profile of the second cam 603.

  On the other hand, as shown in FIG. 2C, when the lever 610 moves forward due to the hydraulic pressure from the hydraulic pressure supply system 609 and the rocker arm 605 and the sub rocker arm 608 are coupled, the first rocker arm 605 has a first state. The first cam 602 acts via the follower 606. As a result, the exhaust valve 122 operates at the valve lift and valve timing in the spark ignition combustion mode according to the profile of the first cam 602.

  3A and 3B are diagrams showing valve timings in the compression self-ignition combustion mode and the spark ignition combustion mode, respectively.

  In the compression self-ignition combustion mode shown in FIG. 3A, the opening degree of the throttle valve 114 is fully opened, and the fuel injection amount from the fuel injection valve 118 is controlled according to the accelerator opening degree.

Further, in order to raise the temperature of the mixed gas to a predetermined temperature, the closing timing EVC of the exhaust valve 122 in the exhaust stroke is advanced to leave combustion gas (hereinafter referred to as internal EGR gas). Raise the temperature of the inhaled new air. By controlling the amount of internal EGR gas, the temperature of the mixed gas can be raised to a predetermined temperature.

As shown in the figure, in order to prevent the internal EGR gas remaining in the intake stroke following the exhaust stroke from flowing back to the intake passage 111, the opening timing IVO of the intake valve 121 is set to the top dead center TDC. On the other hand, the closing timing EVC of the exhaust valve 122 is set symmetrically. Further, the opening timing EVO of the exhaust valve 122 is advanced from the bottom dead center BDC, and the closing timing IVC of the intake valve 121 is retarded from the bottom dead center BDC.

  On the other hand, in the spark ignition combustion mode shown in FIG. 3B, the opening degree of the throttle valve 114 and the fuel injection amount from the fuel injection valve 118 are controlled according to the accelerator opening degree, and the ignition plug 124 is operated at a predetermined timing. By doing so, the compressed air-fuel mixture in the combustion chamber 123 is combusted.

  The opening timing EVO of the exhaust valve 122 is set to an advance side from the bottom dead center BDC, but the closing timing IVC of the intake valve 121 is set to an advance side further than that.

  Since spark ignition combustion has the merit that it can respond to the required output, and compression self-ignition combustion has the merit that fuel consumption is good, it is good to switch both combustions according to driving conditions. For example, it can be set to operate in the compression self-ignition combustion mode in the low-to-medium-rotation operating state of idle or higher and in the low-load to medium-load operation state, and to operate in the spark ignition combustion mode in other cases.

  In the engine EG of this example, the variable valve mechanism 60 of the exhaust valve 122 is step-switched in accordance with two combustion modes such as compression self-ignition combustion and spark ignition combustion. When such variable valve mechanism 60 is used, switching is performed. At times, there are the following problems.

  That is, when switching from the spark ignition combustion mode to the compression self-ignition combustion mode, the variable valve mechanism 60 of the exhaust valve 122 is switched from the state shown in FIG. 2C to the state shown in FIG. 2B, but the hydraulic pressure of the hydraulic supply system 609 is released. Even if the lever 610 is moved backward by the elastic force of the return spring 611, the lever 610 may be caught by the sub rocker arm 608 and may not come off.

  When switching from the compression self-ignition combustion mode to the spark ignition combustion mode, the variable valve mechanism 60 of the exhaust valve 122 is switched from the state shown in FIG. 2B to the state shown in FIG. 2C, but the hydraulic pressure of the hydraulic pressure supply system 609 is applied. Even if the lever 610 is moved forward, the lever 610 is repelled by the sub rocker arm 608 and may not be engaged.

  In addition to the malfunction of the lever 610 at the time of switching, there may be a case where the responsiveness of the switching operation of the variable valve mechanism 60 is poor due to insufficient elastic force of the return spring 611 or insufficient hydraulic pressure of the hydraulic pressure supply system 609.

  For this reason, in this example, the following control is executed in view of the response at the time of switching of the variable valve mechanism 60.

  FIG. 4 is a graph showing control at the time of switching from compression self-ignition combustion to spark ignition combustion, and FIG. 5 is a flowchart showing the control procedure.

  The upper half of FIG. 4 shows the exhaust valve / intake valve opening period and pressure sensor according to the stroke when the lever 610 of the variable valve mechanism 60 operates normally and the switching of the exhaust valve 122 is performed normally. A graph showing in-cylinder pressure, fuel injection timing, combustion timing and ignition timing detected by 117, and the lower half of the figure shows that the lever 610 of the variable valve mechanism 60 does not operate normally and the switching of the exhaust valve 122 is delayed. 6 is a graph showing the valve opening period of the exhaust valve / intake valve, the in-cylinder pressure detected by the pressure sensor 117, the fuel injection timing, the combustion timing, and the ignition timing for each stroke. The switching signal from the compression self-ignition combustion mode to the spark ignition combustion mode is input at time T in FIG.

  First, as shown in the left half of the figure, in the combustion cycle in the transition process of the switching operation of the variable valve mechanism 60 when the mode switching signal is input, the compression self-ignition combustion mode is continued, and the exhaust valve 122 in the exhaust stroke. After the closing timing, the first fuel injection is performed, and the second fuel injection is performed in the subsequent intake stroke. Then, compression self-ignition combustion is performed in the vicinity of the top dead center after the compression stroke, and the operation proceeds to the expansion stroke.

  Even if the lever 610 of the variable valve mechanism 60 operates normally in the combustion cycle of this transition process, in the subsequent combustion cycle, the top dead from the closing timing EVC of the exhaust valve 122 in the exhaust stroke in the compression self-ignition combustion. The first fuel injection is continued until the point TDC (step S1 in FIG. 5).

Then, detecting the in-cylinder pressure by the pressure sensor 117 at step S2, when the cylinder pressure and the detected is lower than the predetermined value P _0, the closing timing EVC of exhaust valve 122 is delayed from the state shown in FIG. 3A hiding 3B, the process proceeds to step S3, and the second fuel injection is performed in the subsequent intake stroke.

  The amount of fuel injection for the second time is adjusted according to the retard angle of the closing timing EVC of the exhaust valve 122, that is, the in-cylinder pressure detected by the pressure sensor 117. That is, the close timing EVC of the exhaust valve 122 is increased so as to approximate the fuel injection amount in the spark ignition combustion mode as the valve timing in the spark ignition combustion mode shown in FIG.

  Then, as shown in the upper right of FIG. 4, the spark plug 124 is operated in the vicinity of the top dead center after the compression stroke. As a result, the transition to the spark ignition combustion mode is completed. Therefore, in the next combustion cycle, the fuel injection in the exhaust process is terminated, the fuel injection is performed only in the intake stroke, and the ignition plug 124 is near the top dead center after the compression stroke. , And spark ignition combustion. Although illustration is omitted, after this, the variable valve mechanism 60 of the intake valve 121 is actuated to shift to the valve timing shown in FIG. 3B.

  Note that, when the operation of the variable valve mechanism 60 is normal, the closing timing EVC of the exhaust valve 122 is retarded, so that the fuel by the first fuel injection in the exhaust stroke is exhausted as unburned fuel ( As shown in FIG. 8, the amount of unburned gas discharged decreases as the exhaust valve sucks back as the closing timing EVC of the exhaust valve 122 is retarded from the top dead center. The amount of unburned gas emission decreases as the fuel injection timing is delayed. Therefore, it is desirable to retard the closing timing EVC of the exhaust valve 122 and the first fuel injection timing.

  Returning to step S2 of FIG. 5, even when the lever 610 of the variable valve mechanism 60 does not operate normally in the switching transition process as shown in the lower part of FIG. 4, in the subsequent combustion cycle, in the compression self-ignition combustion. The first fuel injection is continued from the closing timing EVC of the exhaust valve 122 in the exhaust stroke to the top dead center TDC (step S1 in FIG. 5).

In this case, since closing timing EVC of exhaust valve 122 remains before the cylinder pressure detected by the pressure sensor 117 is higher than the predetermined value P ₀ As with compression self-ignition combustion mode. Accordingly, the process proceeds from step S2 in FIG. 5 to step S4, and the second fuel injection is performed in the subsequent intake stroke.

  The second fuel injection amount in the intake stroke is adjusted according to the retard angle of the closing timing EVC of the exhaust valve 122, that is, the in-cylinder pressure detected by the pressure sensor 117. That is, as the closing timing EVC of the exhaust valve 122 is closer to the valve timing in the compression self-ignition combustion mode shown in FIG. 3A, the exhaust valve 122 is decreased to approximate the fuel injection amount in the compression self-ignition combustion mode.

As a result, the compression self-ignition combustion mode is continued as shown in the lower right of FIG. 4, compression self-ignition combustion is performed near the top dead center after the compression stroke, and the in-cylinder pressure is set to a predetermined value P ₀ in step S2. The process of step S4 is continued until the following is reached.

  FIG. 6 is a graph showing control at the time of switching from spark ignition combustion to compression self-ignition combustion, and FIG. 7 is a flowchart showing the control procedure.

  The upper half of FIG. 6 shows the exhaust valve / intake valve opening period and pressure sensor according to the stroke when the lever 610 of the variable valve mechanism 60 operates normally and the switching of the exhaust valve 122 is performed normally. A graph showing in-cylinder pressure, fuel injection timing, combustion timing and ignition timing detected by 117, and the lower half of the figure shows that the lever 610 of the variable valve mechanism 60 does not operate normally and the switching of the exhaust valve 122 is delayed. 6 is a graph showing the valve opening period of the exhaust valve / intake valve, the in-cylinder pressure detected by the pressure sensor 117, the fuel injection timing, the combustion timing, and the ignition timing for each stroke. The switching signal from the spark ignition combustion mode to the compression self-ignition combustion mode is input at time T in FIG.

  First, when a mode switching signal is input, the variable valve mechanism 60 of the intake valve 121 is operated in step S11 of FIG. 7 to shift the intake valve 121 from the timing shown in FIG. 3B to the timing shown in FIG. 3A. Next, in step S12, the variable valve mechanism 60 of the exhaust valve 122 is operated to shift the exhaust valve 122 from the timing shown in FIG. 3B to the timing shown in FIG. 3A.

  At this time, as shown in the left half of FIG. 6, the spark ignition combustion mode is continued in the combustion cycle in the transition process of the switching operation of the variable valve mechanism 60 of the exhaust valve 122 when the mode switching signal is input. Fuel injection is performed in the stroke, and the spark plug 124 is operated in the vicinity of the top dead center after the compression stroke, and spark ignition combustion is performed to shift to the expansion stroke. In the next combustion cycle, the first fuel injection in the exhaust stroke corresponding to the compression self-ignition combustion is performed (step S12).

Then, in step S13, detects the in-cylinder pressure by the pressure sensor 117, when the cylinder pressure and the detected is higher than the predetermined value P _0, the advance closing timing EVC of exhaust valve 122 is in the state shown in FIG. 3B hiding 3A, the process proceeds to step S14, and the second fuel injection is performed in the subsequent intake stroke.

  This second fuel injection amount is adjusted according to the advance angle of the closing timing EVC of the exhaust valve 122, that is, the in-cylinder pressure detected by the pressure sensor 117. That is, as the closing timing EVC of the exhaust valve 122 is closer to the valve timing in the compression self-ignition combustion mode shown in FIG. 3A, the exhaust valve 122 is decreased to approximate the fuel injection amount in the compression self-ignition combustion mode.

  Then, as shown in the upper right of FIG. 6, the spark plug 124 is operated near the top dead center after the compression stroke. As a result, the transition to the compression self-ignition combustion mode is completed. Therefore, in the next combustion cycle, the operation of the spark plug 124 is terminated and the compression self-ignition combustion is performed.

  Returning to step S13 in FIG. 7, even if the lever 610 of the variable valve mechanism 60 does not operate normally in the switching transition process as shown in the lower part of FIG. 6, in the subsequent combustion cycle, the compression self-ignition combustion is performed. The first fuel injection in the corresponding exhaust stroke is performed (step S12).

In this case, since closing timing EVC of exhaust valve 122 remains before the cylinder pressure detected is just as lower than the predetermined value P ₀ and the spark ignition combustion mode by the pressure sensor 117. Accordingly, the process proceeds from step S13 in FIG. 7 to step S15, and the second fuel injection is performed in the subsequent intake stroke.

  The second fuel injection amount in the intake stroke is adjusted according to the advance angle of the closing timing EVC of the exhaust valve 122, that is, the in-cylinder pressure detected by the pressure sensor 117. That is, the close timing EVC of the exhaust valve 122 is increased so as to approximate the fuel injection amount in the spark ignition combustion mode as the valve timing in the spark ignition combustion mode shown in FIG.

As a result, the spark ignition combustion mode is continued as shown in the lower right of FIG. 6, and spark ignition combustion is performed in the vicinity of the top dead center after the compression stroke. In step S13, the in-cylinder pressure becomes equal to or higher than the predetermined value P ₀ . The process of step S15 is continued until it becomes.

  As described above, according to the engine EG of this example, when switching from compression self-ignition combustion to spark ignition combustion, the switching operation of the exhaust valve 122 is caused by a malfunction of the lever 610 of the variable valve mechanism 60 of the exhaust valve 122 or the like. Even if the operation is not performed, the fuel injection is performed between the closing timing EVC of the exhaust valve 122 and the top dead center TDC in the compression self-ignition combustion until the switching of the exhaust valve 122 is completed. Thus, it is possible to suppress the rich misfire of the spark ignition combustion due to the decrease in fresh air.

  On the other hand, when switching from spark ignition combustion to compression self-ignition combustion, even if the switching operation of the exhaust valve 122 is not performed due to the malfunction of the lever 610 of the variable valve mechanism 60 of the exhaust valve 122 or the like, Until the switching of the valve 122 is completed, ignition by the spark plug 124 is continued and fuel injection in the intake stroke is continued, so that spark ignition combustion is continued, thereby suppressing lean misfire of compression self-ignition combustion due to fuel shortage can do.

  The engine control unit 11 corresponds to a control unit according to the present invention, and the pressure sensor 117 corresponds to a pressure detection unit and a closing timing detection unit according to the present invention.

EG ... Engine (internal combustion engine)
11 ... Engine control unit (control means)
111 ... intake passage 112 ... air filter 113 ... air flow meter 114 ... throttle valve 115 ... collector 116 ... throttle valve actuator 116a ... throttle sensor 117 ... pressure sensor 118 ... fuel injection valve 119 ... cylinder 120 ... piston 121 ... intake valve 122 ... exhaust Valve 123 ... Combustion chamber 124 ... Spark plug 125 ... Exhaust passage 126 ... Air-fuel ratio sensor 127 ... Exhaust purification catalyst 128 ... Oxygen sensor 129 ... Muffler 130 ... Crankshaft 131 ... Crank angle sensor 132 ... Cooling jacket 133 ... Water temperature sensor 60 ... Possible Variable valve mechanism

Claims (6)

In a combustion control device for an internal combustion engine capable of switching between spark ignition combustion and compression self-ignition combustion by internal EGR gas,
When switching from the compression self-ignition combustion to the spark ignition combustion, or when switching from the spark ignition combustion to the compression self-ignition combustion, until the closing timing of the exhaust valve shifts to a predetermined time, the compression self-ignition combustion A combustion control apparatus for an internal combustion engine, comprising control means for executing control for injecting fuel between a closing timing of an exhaust valve and a top dead center of an exhaust stroke. The combustion control device for an internal combustion engine according to claim 1,
A pressure detecting means for detecting the in-cylinder pressure;
The control means is a combustion control device for an internal combustion engine that determines whether or not the closing timing of the exhaust valve has shifted to the predetermined timing based on the in-cylinder pressure. The combustion control apparatus for an internal combustion engine according to claim 1 or 2,
The control means, when switching from the compression self-ignition combustion to the spark ignition combustion, or when switching from the spark ignition combustion to the compression self-ignition combustion, until the closing timing of the exhaust valve shifts to the predetermined time, A combustion control device for an internal combustion engine that executes control for injecting fuel at least in an intake stroke or a compression stroke. The combustion control apparatus for an internal combustion engine according to claim 3,
A closing timing detecting means for detecting the closing timing of the exhaust valve;
The combustion control device for an internal combustion engine, wherein the control means sets an injection amount of fuel in the intake stroke or compression stroke according to the closing timing of the exhaust valve. In the combustion control device for an internal combustion engine according to any one of claims 1 to 4,
When the control means switches from the compression self-ignition combustion to the spark ignition combustion, the internal combustion engine combustion control apparatus sets the predetermined timing to a timing after the top dead center of the exhaust stroke. In the combustion control device for an internal combustion engine according to any one of claims 1 to 5,
When switching from the spark ignition combustion to the compression self-ignition combustion, the control means continues the ignition of the spark ignition combustion and the combustion injection in the intake stroke until the closing timing of the exhaust valve shifts to the predetermined timing. A combustion control device for an internal combustion engine that executes control for increasing the fuel injection amount in the intake stroke.

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