JP2018105171A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine capable of improving combustion efficiency while suppressing occurrence of knocking and combustion fluctuation, and improving exhaust gas characteristic in a case of having a main combustion chamber and an auxiliary combustion chamber.SOLUTION: A control device 1 of an internal combustion engine 3 includes an ECU 2. The ECU 2 executes retardation control for controlling an ignition timing of an air-fuel mixture in the auxiliary combustion chamber 3d to a retard side with respect to that when a catalyst is activated through an ignition plug 8, when an inactive state of the catalyst is estimated (step 5), and holds an air-fuel ratio of the air-fuel mixture in a main combustion chamber 3c at a value before start of the retardation control through a main fuel injection valve 6, and controls an air-fuel ratio of the air-fuel mixture in the auxiliary combustion chamber 3d to a rich side with respect to that when the retardation control is not executed, through an auxiliary fuel injection valve 7, when the retardation control is executed (step 4).SELECTED DRAWING: Figure 3

Description

  The present invention relates to a control device for an internal combustion engine that ignites an air-fuel mixture in a sub-combustion chamber with an ignition device and burns the air-fuel mixture in a main combustion chamber using the ignited air-fuel mixture as a fire type.

  Conventionally, what was described in patent document 1 is known as a control apparatus of an internal combustion engine. This internal combustion engine is of a type that fuels a gas such as city gas, and includes a main combustion chamber and a sub-combustion chamber, and a main fuel injection valve and a sub-fuel supply that supply fuel gas to the main combustion chamber and the sub-combustion chamber, respectively. A valve and a spark plug for igniting the fuel gas in the auxiliary combustion chamber are provided.

  This control device includes a phase angle sensor, an in-cylinder pressure sensor, and the like, and executes knocking suppression control as described below. Specifically, large knocks, small knocks, misfires, and the like are determined for each cylinder based on the detection signals of the two sensors, and the number of cycles in which a small knock has occurred while the predetermined number of cycles elapses and the predetermined number of cycles. Is calculated as a knocking appearance rate SEV, and an appearance rate average value SEVave, which is a moving average value thereof, is calculated. Next, a deviation ΔSET between this and the appearance rate target value SEVset is calculated, and a correction value ΔIGNsev is calculated by multiplying the deviation ΔSET by a gain K1.

  Further, a reference value IGNave is calculated as a moving average value of the ignition timing command value IGN, and a primary target value IGNset1 is calculated by adding a correction value ΔIGNsev thereto. As described above, the primary target value IGNset1 is calculated so that the small knock can be suppressed. Further, the number of cycles Nm in which a large knock has occurred while the predetermined number of cycles elapses is calculated, and when this is equal to or greater than the predetermined value M, the value K-1 is subtracted from the value N and multiplied by the gain K2. Thus, the retardation amount ΔIGNm is calculated, and the secondary target value IGNset2 is calculated by subtracting the retardation amount ΔIGNm from the primary target value IGNset1. As described above, the secondary target value IGNset2 is calculated so as to suppress a large knock. Based on the secondary target value IGNset2, the ignition timing command value IGN is calculated. As described above, the occurrence of large knocks and small knocks is suppressed by calculating the ignition timing command value IGN.

JP 2010-84681 A

  According to the control device of Patent Document 1 above, in order to suppress the occurrence of large knocks, the primary target value IGNset1 is retarded by the retardation amount ΔIGNm. There is a possibility that the combustion efficiency may be reduced due to the deviation.

  In addition, in the case of an internal combustion engine having a main combustion chamber and a sub-combustion chamber and mounted on a vehicle as a power source, the ignition timing is retarded to quickly activate the catalyst at the time of starting. Is generally executed, and in such a case, there is a risk of lowering combustion efficiency and increasing combustion fluctuation.

  Further, in the case of an internal combustion engine having a main combustion chamber and a sub-combustion chamber and mounted on a vehicle as a power source and operated by lean burn, in order to recover the NOx purification capability of the NOx purification catalyst in the exhaust passage. In general, the control system executes rich spike control for controlling the air-fuel ratio to be richer than during lean burn operation. Even in such an internal combustion engine, when the air-fuel ratio is switched between a value for lean burn operation and a value for rich spike control, combustion fluctuations are likely to occur and exhaust gas characteristics may be degraded.

  The present invention has been made to solve the above problems, and in the case where the main combustion chamber and the sub-combustion chamber are provided, the combustion efficiency can be improved while suppressing the occurrence of knocking and combustion fluctuation, and the exhaust gas characteristics. An object of the present invention is to provide a control device for an internal combustion engine that can improve the engine.

  In order to achieve the above object, according to the first aspect of the present invention, a main combustion chamber 3c and a sub-combustion chamber 3d communicating with each other are provided for each cylinder 3a, and the fuel is supplied to the main combustion chamber 3c. A main fuel supply device (main fuel injection valve 6) for generating an air-fuel mixture, and a sub fuel supply device (sub fuel) for generating an air-fuel mixture in the sub-combustion chamber 3d by supplying fuel to the sub-combustion chamber 3d. A control device 1 for an internal combustion engine 3 including an injection valve 7) and an ignition device (ignition plug 8) for igniting an air-fuel mixture in the auxiliary combustion chamber 3d, wherein a predetermined retardation condition is satisfied Based on the determination result of the retard condition determination means (ECU 2, steps 2 and 3) for determining whether or not and the retard condition determination means, the ignition device (ignition plug) 8) through the ignition timing of the air-fuel mixture in the auxiliary combustion chamber 3d The ignition timing control means (ECU 2, step 5) for executing the retard control for controlling the retard to the retard side than when the predetermined retard condition is not established, and the main fuel when the retard control is executed The air-fuel ratio of the air-fuel mixture in the main combustion chamber 3c is maintained at a value before the start of the retard control via the supply device (main fuel injection valve 6), and the auxiliary fuel supply device (sub fuel injection valve 7) is And an air-fuel ratio control means (ECU2, step 4) for controlling the air-fuel ratio of the air-fuel mixture in the auxiliary combustion chamber 3d to a richer side than when the retard control is not executed. .

  According to the control device for the internal combustion engine, it is determined whether or not a predetermined retardation condition is satisfied, and when the predetermined retardation condition is satisfied, the mixing in the auxiliary combustion chamber is performed via the ignition device. Delay angle control is executed for controlling the ignition timing to the retard side compared to when the predetermined retard condition is not satisfied. Further, when the retard control is executed, the air-fuel ratio of the air-fuel mixture in the main combustion chamber is maintained at the value before the start of the retard control via the main fuel supply device, and via the auxiliary fuel supply device. Therefore, the air-fuel ratio of the air-fuel mixture in the sub-combustion chamber is controlled to be richer than when the retard control is not executed, so that while the retard control is being performed, the ignition timing is controlled to the retard side, With the air-fuel ratio in the main combustion chamber held at a value before the start of the retard control, the ignitability of the air-fuel mixture in the sub-combustion chamber can be ensured and combustion stability can be ensured. As a result, good combustion efficiency and combustion stability can be ensured even under conditions that require the ignition timing to be controlled more retarded, such as when the catalyst is in an inactive state, and high commerciality can be ensured. it can.

  According to a second aspect of the present invention, in the control device 1 for the internal combustion engine 3 according to the first aspect, the retard condition determining means is such that the catalyst (catalyst device 10) in the exhaust passage 9 of the internal combustion engine 3 is in an inactive state. When it is estimated, it is determined that a predetermined retardation condition is satisfied.

  According to this control device for an internal combustion engine, when the catalyst of the internal combustion engine is estimated to be in an inactive state, the retard angle control is executed. Therefore, while ensuring good combustion efficiency and combustion stability, the catalyst Can be activated quickly. Thereby, merchantability can be improved.

  In the invention according to claim 3, a main combustion chamber 3c and a sub-combustion chamber 3d communicating with each other are provided for each cylinder 3a, and an air-fuel mixture is generated in the main combustion chamber 3c by supplying fuel to the main combustion chamber 3c. A main fuel supply device (main fuel injection valve 6), a sub fuel supply device (sub fuel injection valve 7) for generating an air-fuel mixture in the sub combustion chamber 3d by supplying fuel to the sub combustion chamber 3d; A control device for the internal combustion engine 3 including an ignition device (ignition plug 8) for igniting the air-fuel mixture in the chamber 3d, and a knocking determination means (ECU2, ECU2) for determining whether or not knocking has occurred in the internal combustion engine 3 Based on the determination results of steps 12 and 13 and the knocking determination means, when knocking occurs, the air-fuel ratio of the air-fuel mixture in the auxiliary combustion chamber 3d is determined via the auxiliary fuel supply device (subfuel injection valve 7). Knocking Air-fuel ratio control means (ECU 2, step 14) for controlling the rich side than when not with, characterized in that it comprises a.

  According to this control device for an internal combustion engine, whether or not knocking has occurred in the internal combustion engine is determined, and when knocking occurs, the air-fuel ratio of the air-fuel mixture in the auxiliary combustion chamber is knocked via the auxiliary fuel supply device. It is controlled to the rich side than when not. Thereby, when knocking occurs, the combustion speed of the air-fuel mixture in the sub-combustion chamber can be increased more than when knocking does not occur, and the combustion center of gravity position can be advanced (see FIG. 6 (a) and 6 (b)), it is possible to suppress the occurrence of knocking without controlling the ignition timing to the retard side before the occurrence of knocking. As a result, combustion efficiency can be improved while suppressing the occurrence of knocking.

  In the invention according to claim 4, a main combustion chamber 3c and a sub-combustion chamber 3d communicating with each other are provided for each cylinder 3a, and an air-fuel mixture is generated in the main combustion chamber 3c by supplying fuel to the main combustion chamber 3c. A main fuel supply device (main fuel injection valve 6), a sub fuel supply device (sub fuel injection valve 7) for generating an air-fuel mixture in the sub combustion chamber 3d by supplying fuel to the sub combustion chamber 3d; A control device for the internal combustion engine 3 including an ignition device (ignition plug 8) for igniting the air-fuel mixture in the chamber 3d, and a main fuel supply device (main fuel injection valve) according to the operating state of the internal combustion engine 3 6) and the second predetermined value smaller than the first predetermined value from the first predetermined value equal to or higher than the stoichiometric air-fuel ratio via the auxiliary fuel supply device (sub fuel injection valve 7). Air-fuel ratio switching control to switch to When performing the control, the air-fuel ratio control for controlling the air-fuel ratio of the air-fuel mixture in the sub-combustion chamber 3d to be richer than before the execution of the air-fuel ratio switching control is performed via the sub fuel supply device (sub fuel injection valve 7). When the means (ECU 2, steps 23 to 30) and the air-fuel ratio switching control are executed, the ignition timing of the air-fuel mixture in the auxiliary combustion chamber 3d is controlled by the air-fuel ratio switching control via the ignition device (ignition plug 8). Ignition timing control means (ECU2, step 25) for controlling the retard side more than before execution.

  According to the control device for an internal combustion engine, the air fuel ratio of the entire air-fuel mixture in the cylinder is set to the first predetermined value equal to or higher than the theoretical air fuel ratio via the main fuel supply device and the auxiliary fuel supply device according to the operating state of the internal combustion engine. The air-fuel ratio switching control for switching from 1 to a second predetermined value smaller than the first predetermined value is executed. When the air-fuel ratio switching control is executed, the air-fuel ratio of the air-fuel mixture in the auxiliary combustion chamber is controlled to be richer than before the air-fuel ratio switching control is executed via the auxiliary fuel supply device. When the air-fuel mixture in the sub-combustion chamber is ignited during execution of the fuel ratio switching control, it is possible to avoid deterioration in ignitability due to a delay in response of the in-cylinder gas amount. Thereby, combustion stability can be ensured and combustion efficiency can be improved. In addition, when the air-fuel ratio switching control is executed, the ignition timing of the air-fuel mixture in the sub-combustion chamber is controlled to be retarded from before the execution of the air-fuel ratio switching control via the ignition device. It is possible to avoid an increase in the NOx emission amount accompanying the increase in the combustion temperature, and to improve the exhaust gas characteristics. As described above, during the execution of the air-fuel ratio switching control, it is possible to ensure combustion stability and improve the exhaust gas characteristics, and to improve the merchantability.

It is a figure which shows typically the structure of the control apparatus which concerns on 1st Embodiment of this invention, and the internal combustion engine to which this is applied. FIG. 2 is a partially enlarged view of FIG. 1 showing a schematic configuration around the auxiliary combustion chamber of the internal combustion engine. It is a flowchart which shows the engine control process by the control apparatus of 1st Embodiment. It is a figure which shows the relationship between (a) ignition timing and exhaust gas temperature in an internal combustion engine, and (b) ignition timing and combustion fluctuation. It is a flowchart which shows the engine control process by the control apparatus of 2nd Embodiment. It is a figure which shows the relationship between the air fuel ratio of a subcombustion chamber and combustion speed in an internal combustion engine, and the relationship between the air fuel ratio of a subcombustion chamber and a combustion gravity center position. It is a flowchart which shows the engine control process by the control apparatus of 3rd Embodiment. It is a figure which shows the relationship between (a) ignition timing and NOx discharge | emission amount in an internal combustion engine, and (b) the air fuel ratio of a subcombustion chamber, and combustion stability.

  Hereinafter, a control apparatus for an internal combustion engine according to a first embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the control device 1 according to the present embodiment controls an operating state of an internal combustion engine (hereinafter referred to as “engine”) 3 and includes an ECU 2. The ECU 2 executes engine control processing and the like as will be described later.

  The engine 3 uses gasoline as fuel, and is mounted on a vehicle (not shown) as a power source. The engine 3 is a multi-cylinder type having a plurality of sets of cylinders 3a and pistons 3b (only one set is shown), and an intake valve and an exhaust valve (both not shown) are provided for each cylinder 3a. During operation of the engine 3, an intake operation into the cylinder 3a and an exhaust operation from the cylinder 3a are performed by the intake valve and the exhaust valve, respectively.

  The intake passage 4 of the engine 3 is provided with a throttle valve mechanism 5 and a main fuel injection valve 6 (main fuel supply device) in order from the upstream side. The throttle valve mechanism 5 includes a throttle valve 5a and a TH actuator 5b that opens and closes the throttle valve 5a. The throttle valve 5a is rotatably provided in the middle of the intake passage 4, and changes the flow rate of air passing through the throttle valve 5a by the change in the opening degree accompanying the rotation.

  The TH actuator 5b is a combination of a motor connected to the ECU 2 and a gear mechanism (not shown), and is controlled by the ECU 2 to change the opening of the throttle valve 5a. Thereby, the amount of air sucked into the cylinder 3a is changed during the intake stroke.

  On the other hand, the main fuel injection valve 6 is provided in the intake manifold of the intake passage 4 for each cylinder 3a, is electrically connected to the ECU 2, and is controlled by the ECU 2 so that fuel is introduced into the intake manifold. Spray. The fuel injected from the main fuel injection valve 6 is sucked into the main combustion chamber 3c as the intake valve is opened during the intake stroke, and an air-fuel mixture is generated.

  Further, a main combustion chamber 3c and a sub-combustion chamber 3d are formed between the piston 3b of each cylinder 3a of the engine 3 and the cylinder head. As shown in FIGS. 1 and 2, the auxiliary combustion chamber 3d is provided on the upper side of the main combustion chamber 3c, and on the upper side thereof, the auxiliary fuel injection valve 7 (sub fuel supply device) and the ignition plug 8 (ignition) Device) is arranged.

  The auxiliary fuel injection valve 7 is provided so that the injection port at the tip thereof faces the auxiliary combustion chamber 3d, and is electrically connected to the ECU 2 and controlled by the ECU 2, thereby The fuel is injected into the combustion chamber 3d. Thereby, an air-fuel mixture is generated in the auxiliary combustion chamber 3d.

  The spark plug 8 is provided so that the electrode at the tip thereof faces the subcombustion chamber 3d. The spark plug 8 is discharged by being controlled by the ECU 2 during the combustion stroke, and the mixture in the subcombustion chamber 3d is discharged. Ignite.

  Further, a plurality of communication holes 3f are formed in the bottom wall portion 3e of the auxiliary combustion chamber 3d, and the auxiliary combustion chamber 3d and the main combustion chamber 3c communicate with each other through these communication holes 3f. Thus, as described above, when the air-fuel mixture in the sub-combustion chamber 3d is ignited by the spark plug 8 during the combustion stroke, the ignited air-fuel mixture flows into the main combustion chamber 3c via the communication hole 3f as a fire type. And the air-fuel mixture in the main combustion chamber 3c is combusted.

  In the case of the engine 3, when the operating range of the engine 3 is in the stoichiometric operating range (high load range or extremely low load range) during normal operation, the air-fuel ratio of the entire air-fuel mixture in the cylinder 3a becomes the stoichiometric air-fuel ratio. In the other lean operation region, the air-fuel ratio of the entire air-fuel mixture in the cylinder 3a is controlled to be a value on the lean side of the stoichiometric air-fuel ratio, and the lean burn operation is performed. Is done. In this case, the air-fuel ratio of the entire air-fuel mixture in the cylinder 3a is the ratio between the total intake air amount in the cylinder 3a and the sum of the fuel injection amount by the main fuel injection valve 10 and the fuel injection amount by the sub fuel injection valve 11. Means.

  On the other hand, a catalyst device 10 is provided in the exhaust passage 9. The catalyst device 10 is a combination of a NOx purification catalyst and a three-way catalyst. The NOx purification catalyst captures NOx in exhaust gas under an oxidizing atmosphere and reduces the captured NOx under a reducing atmosphere. The three-way catalyst purifies the exhaust gas by oxidizing HC and CO in the exhaust gas and reducing NOx under a stoichiometric atmosphere.

  In addition, a crank angle sensor 20, a catalyst temperature sensor 21, a knock sensor 22, and an accelerator opening sensor 23 are electrically connected to the ECU 2.

  The crank angle sensor 20 includes a magnet rotor and an MRE pickup, and outputs a CRK signal and a TDC signal, which are pulse signals, to the ECU 2 as the crankshaft (not shown) rotates.

  The CRK signal is output at one pulse every predetermined crank angle (for example, 30 °), and the ECU 2 calculates the engine speed NE (hereinafter referred to as “engine speed”) NE based on the CRK signal. The TDC signal is a signal indicating that the piston 3b of each cylinder 3a is at a predetermined crank angle position slightly before the TDC position of the intake stroke, and one pulse is output for each predetermined crank angle.

  Further, the catalyst temperature sensor 21 is constituted by a thermistor, detects the catalyst temperature Tcat, which is the temperature of the catalyst device 10, and outputs a detection signal representing it to the ECU 2.

  Further, knock sensor 22 is configured by combining a piezoelectric element and a diaphragm, and is fixed to a cylinder block of engine 3 and outputs a detection signal indicating a voltage value corresponding to knocking vibration to ECU 2. . Based on the detection signal of the knock sensor 22, the ECU 2 determines the presence / absence of the occurrence of knocking, the strength of the knocking and the generation cycle.

  On the other hand, the accelerator opening sensor 23 detects a depression amount (hereinafter referred to as “accelerator opening”) AP of an accelerator pedal (not shown) of the vehicle, and outputs a detection signal indicating it to the ECU 2.

  The ECU 2 includes a microcomputer including a CPU, a RAM, a ROM, an I / O interface (all not shown), and the engine 2 according to the detection signals of the various sensors 20 to 23 described above. 3 is determined, and various control processes are executed as described below in accordance with the operation state. In the present embodiment, the ECU 2 corresponds to a retard condition determination unit, an ignition timing control unit, and an air-fuel ratio control unit.

  Next, the engine control process will be described with reference to FIG. In this engine control process, the operation state of the engine 3 is controlled by controlling the operations of the main fuel injection valve 6, the auxiliary fuel injection valve 7 and the spark plug 8, and the ECU 2 determines the timing of generation of the TDC signal. It is executed synchronously.

  As shown in the figure, first, in step 1 (abbreviated as “S1” in the figure, the same applies hereinafter), the required torque TRQ is calculated. The required torque TRQ is calculated by searching a map (not shown) according to the engine speed NE and the accelerator pedal opening AP.

  Subsequently, it progresses to step 2 and performs a catalyst warm-up determination process. In this catalyst warm-up determination process, it is determined whether an execution condition for a catalyst warm-up control process described later is satisfied, and the value of the catalyst warm-up control flag F_CATact is set based on the determination result.

Specifically, when any of the following conditions (a1) to (a3) is satisfied, it is determined that the catalyst warm-up control process execution condition is satisfied, and the catalyst warm-up control flag F_CATact is “ Otherwise, the catalyst warm-up control flag F_CATact is set to “0”.
(A1) The operation time immediately after the start of the engine 3 is equal to or longer than the time estimated that the temperature in the auxiliary combustion chamber has reached the predetermined temperature.
(A2) The catalyst temperature Tcat is below a predetermined temperature.
(A3) The accelerator opening AP is equal to or less than a predetermined opening.

  In step 3 following step 2, it is determined whether or not the catalyst warm-up control flag F_CATact is “1”. When the determination result is YES and the execution condition of the catalyst warm-up control process is satisfied, the catalyst warm-up control process for quickly activating the catalyst device 10 in steps 4 to 5 as described below. Execute.

  Specifically, first, in step 4, a fuel injection control process for warming up the catalyst is executed. In this control process, the fuel injection amounts and injection timings of the fuel injection valves 6 and 7 are determined according to the engine speed NE and the required torque TRQ, and both the fuel injection amounts and injection timings are determined. Fuel injection by the fuel injection valves 6 and 7 is executed.

  At this time, the fuel injection amount by the main fuel injection valve 6 is determined to be the same value as when the execution condition of the catalyst warm-up control process is not satisfied, while the fuel injection amount by the sub fuel injection valve 7 is determined by the catalyst warm-up. It is determined to be a value on the increase side than when the execution condition of the control process is not satisfied. The reason for this will be described later. When the catalyst warm-up control flag F_CATact = 1, the opening degree of the throttle valve 5a is controlled to a value for catalyst warm-up (a value set according to the operating state of the engine 3) in an intake control process (not shown). The

  As a result, the air-fuel ratio of the air-fuel mixture in the main combustion chamber 3c is controlled to the same value as when the execution condition of the catalyst warm-up control process is not established, and the air-fuel ratio in the sub-combustion chamber 3d is empty. The fuel ratio is controlled to a richer value than when the catalyst warm-up control process execution condition is not satisfied. As a result, the ignitability of the air-fuel mixture in the auxiliary combustion chamber 3d is improved.

  Next, the routine proceeds to step 5 where an ignition timing control process for warming up the catalyst is executed. In this control process, the air-fuel mixture in the sub-combustion chamber 3d is ignited at the optimum ignition timing for quickly activating the catalyst device 10 by the spark plug 8. In this case, the ignition timing is set to a value on the retard side relative to when the execution condition of the catalyst warm-up control process is not satisfied. The reason for this will be described later. As described above, after the ignition timing control process for warming up the catalyst is executed in step 5, the present process is terminated.

  On the other hand, when the determination result of step 3 is NO and the execution condition of the catalyst warm-up control process is not satisfied, it is determined that the normal operation of the engine 3 should be executed, and the process proceeds to step 6 to A fuel injection control process is executed.

  In this control process, the fuel injection amounts and injection timings of the fuel injection valves 6 and 7 are determined according to the engine speed NE and the required torque TRQ, and both the fuel injection amounts and injection timings are determined. Fuel injection by the fuel injection valves 6 and 7 is executed. When the catalyst warm-up control flag F_CATact = 0, the opening degree of the throttle valve 5a is controlled to a normal value (a value set according to the operating state of the engine 3) in an intake control process (not shown). .

  As a result, the air-fuel ratio in the main combustion chamber 3c is controlled to a value near the stoichiometric air-fuel ratio or a leaner side than the stoichiometric air-fuel ratio, and the air-fuel ratio in the sub-combustion chamber 3d The air-fuel ratio of the entire air-fuel mixture in the cylinder 3a is controlled to a value equal to or higher than the stoichiometric air-fuel ratio.

  Next, the routine proceeds to step 7 where the normal ignition timing control process is executed. In this control process, the air-fuel mixture in the auxiliary combustion chamber 3d is ignited by the spark plug 8 so that the air-fuel mixture in the main combustion chamber 3c can be properly ignited using the air-fuel mixture in the auxiliary combustion chamber 3d as a fire type. The As described above, after executing the normal ignition timing control process in step 7, the present process is terminated.

  As described above, according to the control device 1 of this embodiment, when the catalyst warm-up control process execution condition is satisfied, the catalyst warm-up control process is executed in steps 4 to 5. At this time, as described above, in the fuel injection control process for warming up the catalyst in step 4, the fuel injection amount by the auxiliary fuel injection valve 7 is increased by a larger amount than when the execution condition of the catalyst warming up control process is not satisfied. In the ignition timing control process for catalyst warm-up in step 5, the ignition timing by the spark plug 8 is controlled to a value on the retard side than when the conditions for executing the catalyst warm-up control process are not satisfied. Is done.

  This is due to the following reason. That is, in order to activate the catalyst device 10 quickly, it is necessary to raise the exhaust temperature quickly. In this case, as shown in FIG. 4 (a), the exhaust gas temperature rises as the ignition timing is controlled to be retarded, so that the ignition timing is delayed as much as possible in order to quickly activate the catalyst device 10. It is necessary to control to the corner side.

  However, when the ignition timing is controlled to the retard side, as shown in FIG. 4B, an event occurs in which the combustion efficiency decreases and the combustion fluctuation increases as the ignition timing is retarded. On the other hand, in the case of the control device 1 of the first embodiment, as described above, the fuel injection amount by the auxiliary fuel injection valve 7 is controlled to a value on the increase side compared with when the catalyst warm-up control process is not executed. Therefore, it is possible to control the ignition timing as late as possible while suppressing the occurrence of combustion fluctuations and increasing the combustion efficiency. As a result, it is possible to quickly activate the catalyst device 10 while suppressing a decrease in combustion efficiency and ensuring combustion stability, and it is possible to ensure high merchantability.

  The first embodiment is an example in which the execution condition of the catalyst warm-up control process is used as the predetermined retardation condition. However, the predetermined retardation condition of the present invention is not limited to this, and the mixing in the sub-combustion chamber is performed. Any condition may be used as long as it is necessary to control the ignition timing to the retard side. For example, the occurrence of knocking may be set as a predetermined retardation condition.

  Next, a control device according to the second embodiment will be described. This control device controls the same engine as the engine 3 of the first embodiment. Compared with the control device 1 of the first embodiment, the control device has the same electrical and mechanical configuration, and FIG. Therefore, the engine control process will be described below with reference to FIG.

  This engine control process is executed by the ECU 2 in synchronization with the generation timing of the TDC signal, similarly to the engine control process of FIG. 3 described above. In the present embodiment, the ECU 2 corresponds to knocking determination means and air-fuel ratio control means.

  As shown in the figure, first, in step 11, the required torque TRQ is calculated by the same method as in step 1 described above.

  Next, the process proceeds to step 12 to execute a knock determination process. This knock determination process determines whether or not the execution condition of the knock suppression control process for suppressing the occurrence of knocking is established based on the detection signal of the knock sensor 22, and based on the determination result, The value of the knock suppression control flag F_KNOCK is set.

  In this case, the knock suppression control flag F_KNOCK is set to “1” when the execution condition of the knock suppression control process is satisfied, and otherwise, the knock suppression control flag F_KNOCK is set to “0”.

  In step 13 following step 12, it is determined whether or not the knock suppression control flag F_KNOCK is “1”. When the determination result is YES and the execution condition of the knock suppression control process is satisfied, the knock suppression control process is executed in steps 14 to 15 as described below.

  Specifically, first, in step 14, a fuel injection control process for suppressing knocking is executed. In this control process, the fuel injection amount and the injection timing of the main fuel injection valve 6 are determined according to the engine speed NE, the required torque TRQ, etc., and the main fuel injection is performed at the determined fuel injection amount and injection timing. Fuel injection by the valve 6 is executed. At that time, the fuel injection amount by the main fuel injection valve 6 is set to the same value as when the execution condition of the knock suppression control process is not satisfied.

  The fuel injection amount and injection timing of the auxiliary fuel injection valve 7 are determined by the method described below. That is, the basic value of the fuel injection amount is calculated according to the engine speed NE, the required torque TRQ, and the like, the knock intensity and the knock frequency are calculated based on the detection signal of the knock sensor 22, and based on the calculation result. Thus, an increase in the fuel injection amount is calculated. Then, the fuel injection amount of the auxiliary fuel injection valve 7 is calculated by adding the increased amount to the basic value, and the injection timing of the auxiliary fuel injection valve 7 is determined according to the fuel injection amount and the engine speed NE. Is done. Further, the fuel injection by the auxiliary fuel injection valve 7 is executed at the fuel injection amount and the injection timing determined as described above.

  When knock suppression control flag F_KNOCK = 1, the opening degree of throttle valve 5a is controlled to a knock suppression value (a value set according to the operating state of engine 3) in an intake control process (not shown). As described above, the fuel injection amount by the auxiliary fuel injection valve 7 is increased more than when the execution condition of the knock suppression control process is not satisfied, and the air-fuel ratio in the auxiliary combustion chamber 3d is controlled to the rich side. The reason for this will be described later.

  Next, the routine proceeds to step 15 where an ignition timing control process for knock suppression is executed. In this control process, the ignition timing is set to the same value as when the execution condition of the knock suppression control process is not satisfied. As described above, after the ignition timing control process for knock suppression is executed in step 15, this process is terminated.

  On the other hand, if the determination result in step 13 is NO and the execution condition of the knock suppression control process is not satisfied, it is determined that the normal operation of the engine 3 should be executed, and the process proceeds to step 16 where Similarly, the fuel injection control process for normal time is executed. As a result, the air-fuel ratio in the main combustion chamber 3c is controlled to a value near the stoichiometric air-fuel ratio or a value leaner than the stoichiometric air-fuel ratio, and the air-fuel ratio in the sub-combustion chamber 3d is adjusted to the air-fuel ratio in the main combustion chamber 3c. The air-fuel ratio of the entire air-fuel mixture in the cylinder 3a is controlled to a value equal to or higher than the stoichiometric air-fuel ratio.

  Next, the process proceeds to step 17, and after executing the normal ignition timing control process as in step 7 described above, this process ends.

  As described above, according to the control device of the second embodiment, when the execution condition for the knock suppression control process is satisfied, the knock suppression control process is executed in steps 14 to 15. At this time, as described above, in the fuel injection control process for knock suppression in step 14, the amount of fuel injected by the auxiliary fuel injection valve 7 is controlled to be larger than when the execution condition for the knock suppression control process is not satisfied. In the ignition timing control process for knock suppression in step 15, the ignition timing by the spark plug 8 is controlled to the same value as when the execution condition for the knock suppression control process is not satisfied.

  This is due to the following reason. In the case of a general engine, it is known that knocking can be suppressed as the ignition timing is controlled to the retard side. However, when the ignition timing is controlled to the retard side, as described above, an event occurs in which the combustion efficiency decreases and the combustion fluctuation increases. On the other hand, in the case of the control device of the present embodiment, the fuel injection amount by the auxiliary fuel injection valve 7 is controlled to a value on the increase side as compared to when the knock suppression control process is not executed, so that the auxiliary combustion chamber 3d. The air-fuel ratio is controlled to the rich side.

  In this case, as shown in FIG. 6 (a), the more the air-fuel ratio in the sub-combustion chamber 3d is controlled to the richer side, the more the combustion speed of the air-fuel mixture increases, thereby suppressing the occurrence of knocking more effectively. As a result, as shown in FIG. 6B, as the air-fuel ratio in the auxiliary combustion chamber 3d is controlled to be richer, the combustion gravity center position can be advanced.

  As a result, it is possible to suppress the occurrence of knocking while maintaining the ignition timing at the value before the occurrence without controlling the ignition timing to the retard side than before the occurrence of knocking. Thereby, combustion efficiency can be improved while suppressing occurrence of knocking, and high merchantability can be ensured.

  Next, a control device for an internal combustion engine according to a third embodiment will be described. This control device controls the same engine as the engine 3 of the first embodiment. Compared with the control device 1 of the first embodiment, this control device has the same electrical and mechanical configuration, and FIG. Therefore, the engine control process will be described below with reference to FIG.

  This engine control process is executed by the ECU 2 in synchronization with the generation timing of the TDC signal, similarly to the engine control process of FIG. 3 described above. In the present embodiment, the ECU 2 corresponds to air-fuel ratio control means and ignition timing control means.

  As shown in the figure, first, in step 21, the required torque TRQ is calculated by the same method as in step 1 described above.

  Subsequently, it progresses to step 22 and performs a control condition determination process. In this control condition determination process, the values of the stoichiometric operation condition flag F_STOICH and the switching condition flag F_CHANGE are set as described below.

  The stoichiometric operation condition flag F_STOICH indicates whether or not an execution condition for a stoichiometric operation control process, which will be described later, is satisfied, and is specifically set as described below. That is, by searching a map (not shown) according to the engine speed NE and the required torque TRQ, the operating range of the engine 3 is determined, and the operating range of the engine 3 is the stoichiometric operating range where the engine 3 should be operated by stoichiometric combustion. The stoichiometric operation condition flag F_STOICH is set to “1”, and when it is in the lean operation region where the other lean burn combustion should be performed, the stoichiometric operation condition flag F_STOICH is set to “0”.

  On the other hand, the switching condition flag F_CHANGE represents whether or not an execution condition for an operation switching control process described later is satisfied, and is specifically set as described below. That is, when the stoichiometric operation condition flag F_STOICH is switched between “1” and “0” between the previous control timing and the current control timing, until the predetermined period elapses from the switching timing. Is set to “1”, otherwise it is set to “0”.

  In step 23 following step 22, it is determined whether or not the switching condition flag F_CHANGE is “1”. When the determination result is YES and the execution condition of the operation switching control process is satisfied, the operation switching control process is executed in steps 24 to 25 as described below.

  Specifically, first, in step 24, a fuel injection control process for operation switching is executed. In this control process, the fuel injection amounts and injection timings of the fuel injection valves 6 and 7 are determined according to the engine speed NE and the required torque TRQ, and both the fuel injection amounts and injection timings are determined. Fuel injection by the fuel injection valves 6 and 7 is executed.

  At this time, the fuel injection amount by the main fuel injection valve 6 is determined to be the same value as before the execution condition of the operation switching control process is established, while the fuel injection amount by the sub fuel injection valve 7 is determined by the operation switching control process. It is determined to be a value on the increase side than before the execution condition is satisfied. The reason for this will be described later. When the switching condition flag F_CHANGE = 1, the opening degree of the throttle valve 5a is controlled to an operation switching value (a value set according to the operating state of the engine 3) in an unillustrated intake control process.

  Thus, in the operation switching control process when switching from the lean operation control process to the stoichiometric operation control process, the air-fuel ratio of the entire air-fuel mixture in the cylinder 3a is changed from the first predetermined value leaner than the stoichiometric air-fuel ratio to the stoichiometric air-fuel ratio. While being controlled to change to (second predetermined value), the air-fuel ratio in the auxiliary combustion chamber 3d is controlled to a richer value than during execution of the lean operation control process. This is to compensate for the response delay of the in-cylinder gas amount due to the response delay characteristic of the throttle valve 5a and to improve the ignitability of the air-fuel mixture in the auxiliary combustion chamber 3d.

  On the other hand, in the operation switching control process when switching from the stoichiometric operation control process to the lean operation control process, the air-fuel ratio of the entire air-fuel mixture in the cylinder 3a changes from the stoichiometric air-fuel ratio to the first predetermined value described above. The air-fuel ratio in the main combustion chamber 3c is controlled to change from the stoichiometric air-fuel ratio to a leaner value, and the air-fuel ratio in the sub-combustion chamber 3d is controlled by the lean operation control process. The value is richer than that during execution, and is controlled to an optimum value for switching from stoichiometric operation control processing to lean operation control processing. As a result, the ignitability of the air-fuel mixture in the auxiliary combustion chamber 3d is improved.

  Next, the routine proceeds to step 25, where ignition timing control processing for operation switching is executed. In this control process, the air-fuel mixture in the auxiliary combustion chamber 3d is ignited at the optimal ignition timing for suppressing knocking by the spark plug 8. In this case, the ignition timing is set to a value on the retard side from the time when the execution condition of the operation switching control process is not satisfied for the reason described later. As described above, in step 25, the ignition timing control process for operation switching is executed, and then this process is terminated.

  On the other hand, if the determination result in step 23 is NO and the execution condition of the operation switching control process is not satisfied, the process proceeds to step 26 to determine whether or not the stoichiometric operation condition flag F_STOICH is “1”. When the determination result is YES and the execution condition of the stoichiometric operation control process is satisfied, the stoichiometric operation control process is executed in steps 27 to 28 as described below.

  Specifically, first, in step 27, a fuel injection control process for stoichiometric operation is executed. In this control process, the fuel injection amounts and injection timings of the fuel injection valves 6 and 7 are determined according to the engine speed NE and the required torque TRQ, and both the fuel injection amounts and injection timings are determined. Fuel injection by the fuel injection valves 6 and 7 is executed.

  At that time, the fuel injection amount by both the fuel injection valves 6 and 7 is increased as compared with the lean burn operation of the engine 3. Thus, during the execution of the stoichiometric operation control process, the air-fuel ratio of the entire air-fuel mixture in the cylinder 3a is controlled to a value corresponding to the stoichiometric air-fuel ratio richer than the air-fuel ratio during the normal lean burn operation.

  Next, the routine proceeds to step 28, where the ignition timing control process for stoichiometric operation is executed. In this control process, the ignition plug 8 ignites at an optimal ignition timing according to the air-fuel ratio of the air-fuel mixture in the auxiliary combustion chamber 3d. As described above, the ignition timing control process for stoichiometric operation is executed in step 28, and then this process is terminated.

  On the other hand, if the determination result in step 26 is NO and the execution condition of the stoichiometric operation control process is not satisfied, the lean operation control process is executed in steps 29 to 30 as described below.

  Specifically, first, at step 29, a fuel injection control process for lean operation is executed. In this control process, the fuel injection amounts and injection timings of the fuel injection valves 6 and 7 are determined according to the engine speed NE and the required torque TRQ, and both the fuel injection amounts and injection timings are determined. Fuel injection by the fuel injection valves 6 and 7 is executed.

  At this time, the fuel injection amount by both the fuel injection valves 6 and 7 is set to a value suitable for the lean burn operation of the engine 3, and thereby, the entire air-fuel mixture in the cylinder 3 a and The air-fuel ratio in the main combustion chamber 3c is controlled to a value that is leaner than the stoichiometric air-fuel ratio.

  Next, the routine proceeds to step 30, where an ignition timing control process for lean operation is executed. In this control process, the ignition plug 8 ignites at an optimal ignition timing according to the air-fuel ratio of the air-fuel mixture in the auxiliary combustion chamber 3d. As described above, after executing the ignition timing control process for lean operation in step 30, this process is terminated.

  As described above, according to the control device of the third embodiment, when the execution condition for the operation switching control process is satisfied, the operation switching control process is executed in steps 24 to 25. At this time, as described above, in the fuel injection control process for operation switching in step 24, when the lean operation control process is switched to the stoichiometric operation control process, the fuel injection amount by the main fuel injection valve 6 is the operation switching control process. On the other hand, the fuel injection amount by the auxiliary fuel injection valve 7 is determined to be a value on the increase side with respect to before the execution condition of the operation switching control process is satisfied. Further, in the ignition timing control process for switching operation in step 25, the air-fuel mixture in the sub-combustion chamber 3d is ignited at an ignition timing that is retarded as compared with when the execution condition of the operation switching control process is not satisfied.

  This is due to the following reason. That is, as shown in FIG. 8A, in the case of a general engine, it is known that the amount of NOx emission can be reduced as the ignition timing is controlled to the retard side, but the ignition timing is retarded. If controlled to be low, the combustion efficiency may decrease. On the other hand, as shown in FIG. 8B, it is known that the combustion stability of the air-fuel mixture becomes higher as the air-fuel ratio of the air-fuel mixture in the auxiliary combustion chamber 3d is controlled to be richer. . In addition to this, when switching from the lean operation control process to the stoichiometric operation control process, a response delay of the in-cylinder gas amount due to the response characteristic of the throttle valve 5a occurs, and combustion may become unstable. By controlling the air-fuel ratio of the air-fuel mixture in the auxiliary combustion chamber 3d to a richer side, it is necessary to compensate for such a response delay of the in-cylinder gas amount and to improve the ignitability of the air-fuel mixture in the auxiliary combustion chamber 3d. is there. Therefore, in the control device of this embodiment, in the operation switching control process when switching from the lean operation control process to the stoichiometric operation control process, the fuel injection amount by the sub fuel injection valve 7 is greater than when the operation switching control process is not executed. Since the air-fuel ratio in the sub-combustion chamber 3d is controlled to the rich side, combustion stability can be ensured while suppressing NOx emission, and high merchantability is ensured. be able to.

  The third embodiment is an example in which the control for switching the engine 3 between the lean burn operation control and the stoichiometric operation control is executed as the air fuel ratio switching control. However, the air fuel ratio switching control of the present invention is not limited to this. Instead, the air-fuel ratio of the entire air-fuel mixture in the cylinder may be switched between a first predetermined value that is greater than or equal to the theoretical air-fuel ratio and a second predetermined value that is smaller than the first predetermined value. For example, as the air-fuel ratio switching control, in order to normally operate the engine 3, normal operation control for controlling the air-fuel ratio to a theoretical air-fuel ratio or a value leaner than that, and NOx adsorbed on the catalyst device 10 are reduced. In addition, control for switching between catalyst regeneration control for controlling the air-fuel ratio to a value richer than the stoichiometric air-fuel ratio may be executed. Even in this case, the same effect as the third embodiment can be obtained.

  Each of the first to third embodiments described above is an example in which the control device of the present invention is applied to an internal combustion engine for a vehicle. However, the control device of the present invention is not limited thereto, and is an internal combustion engine for ships. The present invention is also applicable to an internal combustion engine for an engine or other industrial equipment.

  Further, each embodiment is an example using gasoline as fuel as the internal combustion engine, but the internal combustion engine of the present invention is not limited to this, and an internal combustion engine using light oil or natural gas as a fuel is used. Also good.

  On the other hand, each embodiment is an example in which the main fuel injection valve 6 is used as the main fuel supply device. However, the main fuel supply device of the present invention is not limited to this, and an air-fuel mixture can be generated in the main combustion chamber. Anything is possible. For example, a direct injection type fuel injection valve that directly injects fuel into the main combustion chamber may be used as the main fuel supply device.

  Each embodiment is an example in which the auxiliary fuel injection valve 7 is used as the auxiliary fuel supply device. However, the auxiliary fuel supply device of the present invention is not limited to this, and an air-fuel mixture can be generated in the auxiliary combustion chamber. Anything is possible. For example, a communication passage communicating with the auxiliary combustion chamber and a device for injecting / supplying fuel into the communication passage may be used as the auxiliary fuel supply device.

  Furthermore, although each embodiment is an example using the ignition plug 8 as an ignition device, the ignition device of this invention is not restricted to this, What is necessary is just to be able to ignite the air-fuel mixture in the auxiliary combustion chamber. For example, a glow plug or the like may be used as the ignition device.

1 control device 2 ECU (retard angle condition judging means, ignition timing control means, air-fuel ratio control means, knocking judging means)
DESCRIPTION OF SYMBOLS 3 Internal combustion engine 3a Cylinder 3c Main combustion chamber 3d Subcombustion chamber 6 Main fuel injection valve (main fuel supply device)
7 Sub fuel injection valve (Sub fuel supply device)
8 Spark plug (ignition device)
9 Exhaust passage 10 Catalytic device (catalyst)

Claims (4)

A main combustion chamber and a sub-combustion chamber communicating with each other are provided for each cylinder, and a main fuel supply device for generating an air-fuel mixture in the main combustion chamber by supplying fuel to the main combustion chamber; A control device for an internal combustion engine, comprising: an auxiliary fuel supply device for generating an air-fuel mixture in the auxiliary combustion chamber by fuel supply; and an ignition device for igniting the air-fuel mixture in the auxiliary combustion chamber,
A retard condition determining means for determining whether or not a predetermined retard condition is satisfied;
Based on the determination result of the retardation condition determining means, when the predetermined retardation condition is satisfied, the ignition timing of the air-fuel mixture in the auxiliary combustion chamber is set via the ignition device to the predetermined retardation. Ignition timing control means for executing retard control for controlling to the retard side from when the angle condition is not satisfied,
When the retard control is executed, the air-fuel ratio of the air-fuel mixture in the main combustion chamber is maintained at a value before the start of the retard control via the main fuel supply device, and the auxiliary fuel supply device An air-fuel ratio control means for controlling the air-fuel ratio of the air-fuel mixture in the sub-combustion chamber to a richer side than when not executing the retard control,
A control device for an internal combustion engine, comprising:   2. The retard condition determining means determines that the predetermined retard condition is satisfied when it is estimated that a catalyst in an exhaust passage of the internal combustion engine is in an inactive state. The internal combustion engine control device described. A main combustion chamber and a sub-combustion chamber communicating with each other are provided for each cylinder, and a main fuel supply device for generating an air-fuel mixture in the main combustion chamber by supplying fuel to the main combustion chamber; A control device for an internal combustion engine, comprising: an auxiliary fuel supply device for generating an air-fuel mixture in the auxiliary combustion chamber by fuel supply; and an ignition device for igniting the air-fuel mixture in the auxiliary combustion chamber,
Knocking judging means for judging whether or not knocking occurs in the internal combustion engine;
Based on the determination result of the knocking determination means, when the knocking occurs, the air-fuel ratio of the air-fuel mixture in the auxiliary combustion chamber is set to a richer side than the time when the knocking does not occur via the auxiliary fuel supply device. Air-fuel ratio control means to control to,
A control device for an internal combustion engine, comprising: A main combustion chamber and a sub-combustion chamber communicating with each other are provided for each cylinder, and a main fuel supply device for generating an air-fuel mixture in the main combustion chamber by supplying fuel to the main combustion chamber; A control device for an internal combustion engine, comprising: an auxiliary fuel supply device for generating an air-fuel mixture in the auxiliary combustion chamber by fuel supply; and an ignition device for igniting the air-fuel mixture in the auxiliary combustion chamber,
Depending on the operating state of the internal combustion engine, the air-fuel ratio of the entire air-fuel mixture in the cylinder is changed from the first predetermined value equal to or higher than the theoretical air-fuel ratio to the first predetermined value via the main fuel supply device and the sub fuel supply device. When performing the air-fuel ratio switching control to switch to a second predetermined value smaller than the air-fuel ratio, the air-fuel ratio of the air-fuel mixture in the sub-combustion chamber is set via the sub-fuel supply device when the air-fuel ratio switching control is performed. Air-fuel ratio control means for controlling the air-fuel ratio to be richer than before execution of the air-fuel ratio switching control;
Ignition timing control for controlling the ignition timing of the air-fuel mixture in the auxiliary combustion chamber to be retarded from before the execution of the air-fuel ratio switching control via the ignition device when the air-fuel ratio switching control is executed Means,
A control device for an internal combustion engine, comprising:

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