JP4884516B2 - Ignition control device for internal combustion engine - Google Patents

Description

  The present invention relates to an ignition control device for an internal combustion engine using a multipoint ignition system having a plurality of ignition plugs for one combustion chamber. More specifically, the present invention relates to an operation state in which the pressure in the combustion chamber is high at the ignition timing. In particular, the present invention relates to an ignition control device for an internal combustion engine that can reliably ignite an air-fuel mixture without misfiring.

  As a means for improving the ignitability of the air-fuel mixture, a plurality of ignition plugs are provided for one combustion chamber, and simultaneous ignition for discharging the plurality of ignition plugs at the same timing, or the plurality of ignition plugs at different timings. An internal combustion engine that employs a so-called multipoint ignition system in which an air-fuel mixture is ignited by any of phase ignition to be discharged has been put into practical use.

  In this multi-point ignition method, simultaneous ignition or phase ignition using a plurality of ignition plugs can achieve equalization of the spread of the flame in the combustion chamber and shortening of the flame propagation time. There is an advantage that the engine output can be improved by improving the combustion state.

  In addition, since stable ignitability can be obtained even for an air-fuel mixture with a large concentration distribution (unevenness), it is an ignition system for an internal combustion engine that performs lean combustion and an internal combustion engine that recirculates exhaust gas by recirculating a large amount. Is also effective.

  Conventionally, as an ignition control device for an internal combustion engine employing such a multipoint ignition system, a supercharger is provided in a multipoint ignition system internal combustion engine in which spark plugs are respectively disposed at the center and bore ends of a combustion chamber. When the pressure in the combustion chamber at the ignition timing is greater than a predetermined value due to the operation of the variable compression ratio mechanism or the ignition ratio variable mechanism, the discharge by the spark plug disposed at the bore end is stopped and only the spark plug disposed at the center is A technique for switching to a one-point ignition system that discharges and ignites an air-fuel mixture has been proposed (see, for example, Patent Document 1).

  In a multi-point ignition internal combustion engine in which a spark plug with a narrow plug gap is arranged at the center of the combustion chamber and a spark plug with a wide plug gap is arranged at the bore end, lean combustion and exhaust gas recirculation are performed. One point to perform the multi-point ignition method only when performing, and to stop the discharge by the spark plug disposed at the end of the bore, and to discharge only the spark plug disposed at the central portion to ignite the mixture A technique for switching to a fire system has been proposed (see, for example, Patent Document 2).

  Patent Document 2 also discloses that when the ignition timing is retarded to the vicinity of TDC (TOP Dead Center), discharge by one of the spark plugs is stopped and the other ignition is performed. A technique for switching to a one-point ignition method in which only the plug is discharged to ignite the air-fuel mixture is also disclosed.

  What is common to these conventional technologies is that the required ignition voltage required to cause a discharge in the plug gap of the spark plug becomes too high in an operating state in which the pressure in the combustion chamber at the ignition timing becomes high. Since there is a possibility that misfire may occur, multi-point ignition is prohibited and switched to one-point ignition in an operating state in which the pressure in the combustion chamber at the ignition timing is high.

JP 2007-46474 A JP-A-2005-315105

  In an internal combustion engine to which the above-mentioned prior art is applied, for example, when a turbocharger or a compression ratio variable mechanism is operated, during high load operation, at start-up, when ignition timing is retarded to near TDC, etc. For an operating state in which the pressure in the combustion chamber increases at the ignition timing, there is a risk of causing a misfire due to an increase in the required ignition voltage, so that one-point ignition is performed without giving up performing multi-point ignition. It is.

  As a result, although misfire in the operating state in which the pressure in the combustion chamber becomes high at the ignition timing can be avoided, the operating range for performing multipoint ignition is greatly limited, which is an excellent merit of multipoint ignition. There is a problem that improvement of ignition performance and combustion state cannot be utilized to the maximum extent.

  Further, when performing multi-point ignition by phase ignition, the spark plug discharged first discharges under a pressure generated by compressing the air-fuel mixture in the combustion chamber as the piston rises. However, the spark plug that is discharged later is discharged while the air-fuel mixture is ignited by the previously discharged spark plug and the combustion proceeds, so the pressure is higher than that of the spark plug that was previously discharged. Discharge occurs under (pressure under which combustion pressure is generated).

  Therefore, the wider the interval between the ignition timing of the ignition plug that is discharged first and the ignition timing of the ignition plug that is discharged later, the higher the pressure in the combustion chamber at the ignition timing of the ignition plug that is discharged later. As a result, there is a problem that the required ignition voltage in the spark plug to be discharged later becomes high and causes misfire.

  In particular, Patent Document 2 does not describe any ignition sequence when performing multi-point ignition. If phase ignition is performed, discharge by a spark plug having a wider plug gap is later set. In this case, the required ignition voltage is further increased as the plug gap is wider, and the possibility of misfiring is further increased. Regarding this, it can be considered that measures can be taken by increasing the power supply capacity of the ignition system or increasing the output energy specification of the ignition coil, but this involves an increase in the size and cost of the power supply circuit and ignition coil. Even if such a design change can be taken, repeated discharge of the spark plug while the required ignition voltage is high leads to a reduction in the life of the spark plug. Furthermore, in the worst case, it is conceivable that the required ignition voltage exceeds the pressure limit of the spark plug and is damaged.

  The present invention has been made to solve the above-described problems in the conventional ignition control device for an internal combustion engine, and does not involve the power supply capacity of the ignition system, the increase in size of the ignition coil, and the cost increase. In the above-mentioned prior art, the ignition performance in a wider operating range than in the prior art by actively executing the multi-point ignition even in the operating state where the multi-point ignition was given up. Ignition of an internal combustion engine that can improve the combustion state and suppress the ignition request voltage of the spark plug to be discharged later during phase ignition to be too high to prevent the life and damage of the spark plug. The object is to provide a control device.

An ignition control device for an internal combustion engine according to the present invention is disposed in a combustion chamber of an internal combustion engine, and a combustion in which a first spark plug that ignites an air-fuel mixture in the combustion chamber by discharge in a plug gap and the first spark plug is disposed. A second spark plug which is disposed in the same combustion chamber as the chamber and has an initial value of a plug gap narrower than the first spark plug, and each spark plug of the first spark plug and the second spark plug An ignition control device for an internal combustion engine comprising an ignition control unit for controlling a discharge operation and an ignition timing in the internal combustion engine, wherein the ignition control unit is configured to operate the first control unit while the internal combustion engine is operating in a predetermined high load region . When ignition of the air-fuel mixture is performed by discharge in the spark plugs of both the spark plug and the second spark plug, the second spark plug starts discharging earlier than the first spark plug. It is characterized in that to limit the discharge start order of the first spark plug and the second spark plug as preparative no.

According to the ignition control device for an internal combustion engine according to the present invention, the first ignition plug disposed in the combustion chamber of the internal combustion engine and igniting the air-fuel mixture in the combustion chamber by the discharge in the plug gap, and the first ignition plug are disposed. Each of the second spark plug, the first spark plug, and the second spark plug, which are disposed in the same combustion chamber as the combustion chamber and in which an initial value of a plug gap narrower than the first spark plug is set. An ignition control device for an internal combustion engine comprising an ignition control unit for controlling a discharge operation and ignition timing in a spark plug, wherein the ignition control unit is configured to operate the internal combustion engine during operation in a predetermined high load region. When the mixture is ignited by discharge in the spark plugs of both the first spark plug and the second spark plug, the second spark plug discharges earlier than the first spark plug. Since the discharge start order of the first spark plug and the second spark plug is limited so as not to be damaged, the power supply capacity of the ignition system, the size of the ignition coil, and the cost increase are involved. In addition, since it becomes possible to execute multipoint ignition even in an operating state that is prohibited in the prior art, it is possible to achieve improvement in ignition performance and combustion state in a wider operating range than in the prior art.

  Further, when phase ignition is performed, it is possible to prevent the ignition request voltage in the spark plug to be discharged later from becoming too high, thereby avoiding a decrease in the life or damage of the spark plug.

1 is a schematic configuration diagram showing an internal combustion engine ignition control apparatus according to Embodiment 1 of the present invention; FIG. It is a top view which shows arrangement | positioning of the ignition plug in the ignition control apparatus of the internal combustion engine by Embodiment 1 of this invention. It is a block diagram which shows the control circuit of the ignition system in the ignition control apparatus of the internal combustion engine by Embodiment 1 of this invention only for 1 cylinder. It is explanatory drawing which shows the relationship of the plug gap of a 1st spark plug and a 2nd spark plug. It is a characteristic view which shows the pressure in a combustion chamber in the ignition timing at the time of two-point simultaneous ignition. It is a characteristic view which shows the pressure in a combustion chamber in the ignition timing at the time of two-point phase ignition. FIG. 6 is a characteristic diagram showing the relationship between the pressure in the combustion chamber and the required ignition voltage at the ignition timing. It is a flowchart which shows the control procedure in the ignition control apparatus of the internal combustion engine by Embodiment 1 of this invention.

Embodiment 1 FIG.
Hereinafter, an ignition control apparatus for an internal combustion engine according to Embodiment 1 of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an internal combustion engine ignition control apparatus according to Embodiment 1 of the present invention. In FIG. 1, the combustion chamber 1b of the cylinder 1a in the internal combustion engine 1 is provided with an intake valve 1c, an exhaust valve 1d, and a piston 1e. In addition, two spark plugs, a first spark plug 13a and a second spark plug 13b, and a fuel injection valve 11 are provided so as to face the combustion chamber 1b.

  In the internal combustion engine 1, the intake air amount is adjusted by an electronic control throttle 8 provided in the intake passage 5. The electronic control throttle 8 includes a butterfly valve 8b, a motor 8c for driving the butterfly valve 8b, and a throttle opening sensor 8a for detecting the opening of the butterfly valve 8b.

  The engine control unit (hereinafter referred to as ECU) 2 acquires an output signal of the accelerator position sensor 4 that detects the depression position of the accelerator pedal 3, sends a control signal to the motor 8c, and outputs a control signal from the throttle opening sensor 8a. Based on the butterfly valve opening signal, the butterfly valve 8b is controlled to an appropriate opening. The crank angle sensor 12 detects the crank angle of the crankshaft 1g, the cam angle sensor 10 detects the cam angle of the intake-side camshaft 1h, and the water temperature sensor 17 detects the temperature of the cooling water of the internal combustion engine 1.

  The ECU 2 acquires output signals from the accelerator position sensor 4, the crank angle sensor 12, the cam angle sensor 10, the air flow sensor 7, the water temperature sensor 17, and other sensors (not shown), and determines the ignition timing and Determine the fuel injection amount. Based on each determined value, the fuel injection valve 11 is driven to inject and supply fuel into the combustion chamber 1b, and the first ignition coil 14a connected to the first spark plug 13a and the second ignition The second ignition coil 14b connected to the plug 13b is driven to cause discharge in the plug gaps of the first ignition plug 13a and the second ignition plug 13b to ignite the air-fuel mixture in the combustion chamber 1b. The initial value of the plug gap of the first spark plug 13a is set wider than the initial value of the plug gap of the second spark plug 13b.

  The intake air from which dust and dirt have been removed by the air cleaner 6 is measured for flow rate by the air flow sensor 7, passes through the electronic control throttle 8, is guided to the surge tank 9, and is further introduced from the surge tank 9 to the intake valve 1 c. And is introduced into the combustion chamber 1b. Then, the intake air introduced into the combustion chamber 1b and the fuel spray injected from the fuel injection valve 11 are mixed to form an air-fuel mixture, and the first spark plug 13a and / or the second spark plug 13b The air-fuel mixture is ignited by the discharge and burns.

  The combustion pressure of the air-fuel mixture is transmitted to the piston 1e to reciprocate the piston 1e. The reciprocating motion of the piston 1e is transmitted to the crankshaft 1g via the connecting rod 1f, where it is converted into a rotational motion and taken out as an output of the internal combustion engine 1. The air-fuel mixture after combustion becomes exhaust gas, is discharged to the exhaust manifold 15 through the exhaust valve 1d, is purified by the catalyst 16, and is discharged to the atmosphere.

  FIG. 2 is a plan view showing the arrangement of the spark plugs in the internal combustion engine ignition control apparatus according to Embodiment 1 of the present invention. FIG. 2 (a) shows the first spark plugs 13a and the second spark plugs 13b arranged symmetrically. (B) shows the case of the asymmetrical arrangement in which the first spark plug 13a and the second spark plug 13b are asymmetrically arranged. In both cases (a) and (b), two intake valves 1c are provided on the left side of the first spark plug 13a and the second spark plug 13b, and two exhaust valves 1d are provided on the right side. .

  In the case of the symmetrical arrangement shown in FIG. 2 (a), the first spark plug is substantially symmetrical with respect to the center at a position slightly deviated from the center of the circle (substantially corresponding to the center of the combustion chamber 1b). 13a and a second spark plug 13b are arranged. In the case of the asymmetrical arrangement shown in FIG. 2B, the first spark plug 13a is disposed near the center of the figure, and the second spark plug 13b is disposed at the bore end away from the center. .

  Here, as to which of the arrangements of FIG. 2A and FIG. 2B is adopted, in addition to the restrictions on the layout when the spark plug is mounted, the shape of the combustion chamber 1b and the mixture It is determined at the stage of designing the internal combustion engine based on the formation state of the engine.

  Since it is experimentally known that the central portion of the combustion chamber 1b is originally good in ignitability, reliable discharge and ignition of the air-fuel mixture are important in the spark plug disposed in the central portion. . Therefore, in the case of phase ignition when two spark plugs are arranged asymmetrically as shown in FIG. 2B, the first spark plug that is not discharged later when executing the ignition sequence restriction control. By disposing 13a in the vicinity of the center of the combustion chamber 1b, ignition of the air-fuel mixture in the first spark plug 13a can be made stable and more reliable.

  In the internal combustion engine ignition control apparatus according to Embodiment 1 of the present invention, the initial values of the plug gap d1 of the first spark plug 13a and the plug gap d2 of the second spark plug 13b are such that d1> d2. For example, d1 is about 1.0 [mm], and d2 is about 0.8 [mm].

  FIG. 3 is a block diagram showing an ignition system control circuit for only one cylinder in the internal combustion engine ignition control apparatus according to Embodiment 1 of the present invention. In FIG. 3, the control circuit of the ignition system for one cylinder includes a first spark plug 13a, a second spark plug 13b, a first ignition coil 14a connected to the first spark plug 13a, and a second ignition plug. The second ignition coil 14b connected to the plug 13b and the EUC2 are included.

  The first ignition coil 14a includes a primary winding 141a, a secondary winding 142a, and a driver circuit 143a. One end of the primary winding 141a is connected to the driver circuit 143a, and one end of the secondary winding 142a is connected to one electrode of the first spark plug 13a, and the other end of the primary winding 141a and the secondary winding are connected. The other end of the line 142 a is connected to the battery voltage line 30.

  The second ignition coil 14b includes a primary winding 141b, a secondary winding 142b, and a driver circuit 143b. One end of the primary winding 141b is connected to the driver circuit 143b, and one end of the secondary winding 142b is connected to one electrode of the first spark plug 13b, and the other end of the primary winding 141b and the secondary winding are connected. The other end of the line 142b is connected to the battery voltage line 30 so as to be connected to each other.

  The first ignition coil 14a and the second ignition coil 14b boost the battery voltage from the battery voltage line 30 connected to the primary windings 141a and 141b by the secondary windings 142a and 142b, respectively. Is supplied to one of the electrodes of the spark plugs 13a, 13b. The respective driver circuits 143a and 143b are connected to the ECU 2, and energization of the respective primary windings 141a and 141b is controlled based on a control signal sent from the ECU 2, and at a predetermined timing, the respective driver circuits 143a and 143b are connected. Sparks are discharged from the plug gap, which is the gap between the electrodes of the spark plugs 13a and 13b, to ignite the air-fuel mixture compressed in the combustion chamber 1b.

Next, the ignition request voltage in the spark plug will be described. Generally, the ignition request voltage of the spark plug is determined by Paschen's law expressed by the following equation (1).

V = K × P × d + C (1)

Where V is the ignition request voltage
K is a proportional constant
P is the pressure in the combustion chamber 1b at the ignition timing
d is plug gap
C is a constant determined by the electrode temperature of the spark plug and the concentration of the air-fuel mixture.
As is clear from the equation (1), when the plug gap d is large and the pressure P of the combustion chamber 1b at the ignition timing is large, the ignition request voltage V becomes high.

  Further, for example, when the engine is supercharged by a supercharger or when the compression ratio is increased by operating the compression ratio variable mechanism, the pressure P of the combustion chamber 1b at the ignition timing is further increased. There is a concern that V may become too high, leading to misfire in the worst case. Therefore, the internal combustion engine according to the first embodiment has the following configuration.

  FIG. 4 is an explanatory diagram showing the relationship between the plug gaps of the first spark plug and the second spark plug. FIG. 4A shows the first spark plug 13a in the internal combustion engine according to Embodiment 1 of the present invention. (B) shows the 2nd spark plug 13b. The gap between the center electrode 13a1 and the side electrode 13a2 in FIG. 4A and the gap between the center electrode 13b1 and the side electrode 13b2 in FIG. In the first spark plug 13a shown in FIG. 4A, the plug gap initial value d1 is set, and in the second spark plug 13b shown in FIG. 4B, the plug gap initial value d2 is set. In the internal combustion engine according to the first embodiment, the initial value of each plug gap is set so as to satisfy the relationship of d1> d2.

  Next, when only one of the two spark plugs is discharged (when one-point ignition is performed), or when two spark plugs are discharged simultaneously (two-point simultaneous ignition is performed) The relationship between the ignition timing and the pressure in the combustion chamber at the ignition timing will be described in detail.

  FIG. 5 is a characteristic diagram showing the pressure in the combustion chamber at the ignition timing when two points are ignited simultaneously. That is, the characteristic diagram shown in FIG. 5 includes two ignition plugs in one combustion chamber, and the ignition timing and the ignition timing in the two-point simultaneous ignition in which both of the ignition plugs are discharged simultaneously. The relationship with the pressure in a combustion chamber is shown. In the case of one-point ignition in which only one of the two spark plugs is discharged, the characteristics similar to those shown in FIG. 5 are provided.

  In FIG. 5, the horizontal axis represents the crank angle, the compression stroke in which the piston 1e rises from the BDC (Bottom Dead Center) to the TDC (Top Dead Center), and the piston 1e moves from the TDC to the BDC. The duration of the two strokes of the descending expansion stroke is shown. Further, in FIG. 5, the pressure in the combustion chamber when the internal combustion engine 1 is motored (when the air-fuel mixture is not combusted) is shown by a dashed curve M as an example.

  From FIG. 5, during the motoring operation, the pressure in the combustion chamber becomes the minimum value when the piston is at the lowest BDC, and the pressure inside the combustion chamber becomes the maximum value when the piston is at the highest TDC. I understand that.

  In FIG. 5, for example, when the ignition plug is discharged at three ignition timings Ig1, Ig2, and Ig3, the pressure in the combustion chamber 1b at each ignition timing Ig1, Ig2, and Ig3 is as follows. It shows that it becomes P1, P2, and P3, respectively. That is, in the case of one-point ignition or two-point simultaneous ignition, the pressure in the combustion chamber 1b at the ignition timing is substantially equivalent to that during motoring operation, and is discharged at TDC as in the ignition timing Ig3. Will be discharged under the highest pressure. In other words, the required ignition voltage is highest when discharging at TDC as in the ignition timing Ig3.

  Next, the relationship between the ignition timing and the pressure in the combustion chamber at the ignition timing when the ignition timings of the two spark plugs are shifted and discharged (when two-point phase ignition is executed) will be described.

  FIG. 6 is a characteristic diagram showing the pressure in the combustion chamber at the ignition timing when two-point phase ignition is performed. That is, the characteristic diagram shown in FIG. 6 shows ignition timings when two ignition plugs are provided in one combustion chamber and two-point phase ignition is performed in which the ignition timings of these ignition plugs are shifted and discharged. FIG. 6 is a characteristic diagram showing the relationship between the pressure in the combustion chamber at the ignition timing. However, the amount of air sucked into the cylinder 1a is the same as in FIG.

  In the case of FIG. 6 as well, as in FIG. 5, the horizontal axis represents the crank angle, the compression stroke in which the piston 1e rises from BDC to TDC, and the piston 1e moves from TDC to BDC. The duration of both strokes of the expansion stroke descending is shown. Also in FIG. 6, the pressure in the combustion chamber when the internal combustion engine is motored (when the air-fuel mixture is not combusted) is indicated by a broken line curve M (the same characteristic as the broken line curve M shown in FIG. 5). ing.

  In FIG. 6, for example, when the ignition timing of the spark plug to be discharged first is Ig1, and the ignition timing of the spark plug to be discharged later is Ig2, the pressure in the combustion chamber 1b at each of the ignition timings Ig1 and Ig2 Are P1 and P4, respectively. That is, the spark plug that is discharged first is discharged at a pressure P1 that is substantially equivalent to that during the motoring operation, as in the case of discharging at the ignition timing Ig1 in FIG. However, in the spark plug to be discharged later, as shown by the solid line F in FIG. 6, the air-fuel mixture is ignited by the discharge of the previously discharged spark plug and combustion starts, so that the pressure is higher than the pressure during the motoring operation. Discharge occurs when combustion pressure is generated. That is, in FIG. 5, the discharge is performed at a pressure P4 higher than the pressure P2 when the discharge is performed at the ignition timing Ig2.

  As described above, when the two-point phase ignition is executed, the pressure in the combustion chamber 1b at the ignition timing of the spark plug that is discharged later becomes higher than that during the motoring operation due to the influence of the combustion pressure. As a result, the required ignition voltage also increases, and in some cases, normal discharge cannot be performed, leading to misfire.

  Next, the relationship between the pressures P1, P4 in the combustion chamber and the ignition request voltage when the ignition timings of the two ignition plugs shown in FIG. 6 are Ig1, Ig2 will be described. FIG. 7 is a characteristic diagram showing the relationship between the pressure in the combustion chamber and the required ignition voltage at the ignition timing. In FIG. 7, the ignition request voltage for the pressure P1 in the combustion chamber in the previously discharged spark plug (ignition timing = Ig1) is V1, and the spark plug (ignition timing = Ig2) discharged later is used. Assuming that the required ignition voltage for the pressure P4 in the combustion chamber is V4, the relationship between the pressure in the combustion chamber 1b and the required ignition voltage V at the ignition timing is the plot A in FIG. The spark plug to be discharged later is indicated by plot B in FIG.

  From plots A and B of FIG. 7, it is clear that the required ignition voltage V increases as the pressure P in the combustion chamber at the ignition timing increases. Therefore, in the ignition control apparatus for an internal combustion engine according to the first embodiment of the present invention, ignition is performed later in order to lower the required ignition voltage V at the pressure P4 in the combustion chamber 1b at the ignition timing Ig2. This is dealt with by setting the initial value of the plug gap of the spark plug narrower than the plug gap of the spark plug that ignites first.

  If the plug gap of the ignition plug to be ignited later is shortened, the ignition required voltage V decreases as can be seen from Paschen's law expressed by the equation (1), and the pressure in the combustion chamber 1b at the ignition timing Ig2 It is realized that the required ignition voltage V at P4 is reduced as shown by plot C in FIG.

  Based on the above, in the ignition control device for an internal combustion engine according to Embodiment 1 of the present invention, in the case of two-point phase ignition, the ignition plug to be discharged first is shown in FIG. As the spark plug that selects the first spark plug 13a (plug gap initial value d1) and discharges it later, the second spark plug 13b (plug gap initial value d2, where d1> shown in FIG. 4B) is used. The initial value of the plug gap is set so as to satisfy d2).

  Next, a control procedure in the internal combustion engine ignition control apparatus according to Embodiment 1 of the present invention will be described. FIG. 8 is a flowchart showing a control procedure in the ignition control apparatus for an internal combustion engine according to the first embodiment of the present invention.

  In FIG. 8, in step S1, it is determined whether or not the operating state of the internal combustion engine 1 is a two-point phase ignition execution zone. If the result of determination in step S1 is that the operating state of the internal combustion engine 1 is not in the two-point phase ignition execution zone (NO), the process proceeds from step S1 to step S6, where there is no restriction on the discharge start sequence of the spark plug. Without the process, the drive of each ignition coil 14a, 14b is controlled to exit the process. On the other hand, if the result of determination in step S1 is that the operating state of the internal combustion engine 1 is a two-point phase ignition execution zone (YES), the routine proceeds from step S1 to step S2.

In step S2, it is determined whether or not the internal combustion engine 1 is operating in a predetermined high load region.
If it is determined in step S2 that the internal combustion engine is operating in a predetermined high load region (YES), the process proceeds from step S2 to step S7, and the discharge start order of the spark plug is limited to each ignition coil. Control the drive of 14a and 14b to exit the process. On the other hand, when it is determined in step S2 that the internal combustion engine 1 is not operating in a predetermined high load region (NO), the process proceeds from step S2 to step S3.

  In step S3, it is determined whether or not the internal combustion engine 1 is in a predetermined low temperature state and being started. If it is determined in step S3 that the internal combustion engine is in a predetermined low temperature state and is being started (YES), the process proceeds from step S3 to step S7, and the discharge start order of the spark plugs is limited to limit the ignition coils 14a and 14b. Control the drive of and exit the process. On the other hand, when it is determined in step S3 that the internal combustion engine 1 is not in a predetermined low temperature state and not being started (NO), the process proceeds from step S3 to step S4.

  In step S4, it is determined whether or not the ignition timing determined based on the operating state of the internal combustion engine 1 is on the advance side of TDC and within a predetermined range from TDC. If it is determined in step S4 that the ignition timing is on the advance side of TDC and within a predetermined range from TDC (YES), the process proceeds from step S4 to step S7, and the discharge start sequence of the ignition plug is limited to Control of driving of the ignition coils 14a and 14b is terminated and the process is terminated. On the other hand, if it is determined in step S4 that the ignition timing is on the advance side of TDC and not within the predetermined range from TDC (NO), the process proceeds from step S4 to step S5.

  In step S5, it is determined whether or not the phase difference of the ignition timing (interval of the ignition timing of the ignition plug that ignites first and the ignition plug that ignites later) is equal to or greater than a predetermined value. If it is determined in step S5 that the phase difference of the ignition timing is greater than or equal to a predetermined value (YES), the process proceeds from step S5 to step S7, and the discharge start order of the spark plugs is limited to limit the ignition coils 14a and 14b. Control the drive and exit the process. On the other hand, when it is determined in step S5 that the phase difference of the ignition timing is not equal to or greater than the predetermined value (NO), the process proceeds from step S5 to step S6, and the ignition coil 14a, Control the drive of 14b to exit the process.

  The above control operations are summarized as follows. That is, when the operating state of the internal combustion engine 1 is a two-point phase ignition execution zone (when step S1 is YES), (1) when the internal combustion engine 1 is operating in a predetermined high load region (step S2). Is determined (YES)), or (2) the internal combustion engine 1 is in a predetermined low-temperature state and is being started (when step S3 is determined YES), or (3) the ignition timing is more advanced than TDC. And (1) when it is within a predetermined range from TDC (when step S4 is YES determination), or (4) when the phase difference of the ignition timing is greater than or equal to a predetermined value (step S5 is YES determination) When any one of (4) is established, it is judged that the ignition request voltage is high, and the second spark plug 13b is discharged earlier than the first spark plug 13a. As there is no First ignition plug 13a, and the second spark plug 13b of the discharge start order is limited by the ignition coil 14a, 14b is driven and controlled (in step S7).

  On the other hand, when step S1 is NO, or when all of the determinations of steps S2 to S5 are NO, it is not an operating state in which two-point phase ignition is executed or an operating state in which the ignition request voltage becomes high. The discharge start order of the spark plugs is not limited, and the ignition coils 14a and 14b are driven and controlled based on the ignition method and ignition timing stored in advance in the memory in the ECU 2 (processing in step S6). ).

Next, a supplementary description will be given of the ignition method and ignition timing setting method.
As an ignition system in the ignition control apparatus for an internal combustion engine according to the first embodiment of the present invention, any one of one-point ignition, two-point simultaneous ignition, or two-point phase ignition is used according to the operating state. It is set in advance. At the same time, the ignition timing of each of the two spark plugs is set in advance according to the operating state.

  In an operating state in which the one-point ignition method is set, only the ignition timing of one of the two spark plugs is preset. In the operating state in which the two-point ignition method is set, the ignition timing of each of the two spark plugs is set in advance.

  If the ignition timings of both spark plugs are the same, two-point simultaneous ignition is performed. If the ignition timings of both spark plugs are different, two-point phase ignition is performed. When two-point phase ignition is set, the difference between the ignition timing of the spark plug that is discharged first and the ignition timing of the spark plug that is discharged later is defined as a phase difference, and the ignition is automatically performed from each set ignition timing. The order is also determined.

  The above ignition method and ignition timing are based on, for example, measurement results of combustion consumption, engine output, exhaust gas concentration, combustion state, etc. when the ignition method and ignition timing are comprehensively changed for each operating state. These are determined in advance and stored in the memory in the ECU 2 as the ignition method and ignition timing according to the operating state.

  Further, when the internal combustion engine 1 is actually operated, the current operating state is detected from detection signals from various sensors such as the intake air amount detected by the air flow sensor 7 and the rotational speed detected by the crank angle sensor 12. Based on the detected current operating state, the ignition method and the ignition timing stored in the memory in the ECU 2 are selected.

  As described above, as the state of the internal combustion engine 1 when setting the ignition method and the ignition timing stored in the ECU 2, the plug gap and the compression ratio are in the initial values. However, when the internal combustion engine 1 actually starts to operate, the plug gap gradually widens due to aging and deterioration, or carbon is deposited in the combustion chamber 1b, so that the compression ratio gradually increases and ignition is performed more than in the initial state. There is a concern that the required voltage increases and misfires occur.

  Therefore, in order to prevent misfire from occurring while the operation of the internal combustion engine 1 is continued for a long time with the initially set ignition method and ignition timing, in the first embodiment of the present invention, the ignition request voltage is higher than the initial state. For an operating state in which there is a risk of increasing the value (when any one of the aforementioned (1) to (4) is established), the second spark plug 13b is more than the first spark plug 13a. The discharge start order of the first spark plug 13a and the second spark plug 13b is limited so that the discharge does not occur early.

  Next, a supplementary description will be given of the method for setting each control parameter used in the flowchart of FIG. In step S1 in FIG. 8, it is determined whether or not the operating state of the internal combustion engine 1 is the phase ignition execution zone. As described above, based on the current operating state from the detection signals from the various sensors, the ECU 2 Since the ignition method and the ignition timing stored in the internal memory are selected, it is possible to determine whether or not the current operation state is the phase ignition execution zone.

  Further, since the internal combustion engine 1 increases in air filling amount as the load increases, the air filling amount increases as the load increases, and the pressure in the combustion chamber at the ignition timing increases. Become. In step S2 of FIG. 8, it is determined whether or not the internal combustion engine 1 is operating in a high load region. Here, the intake air amount detected by the airflow sensor 7 and the rotation detected by the crank angle sensor 12 are determined. The amount of air charged in the cylinder 1a is calculated as a load amount from detection signals from various sensors such as speed, and when the load amount is equal to or greater than a predetermined value, it is determined that the region is a “predetermined high load region”. To do.

  In addition, regarding the load amount corresponding to the threshold value for determining the “predetermined high load region”, when the ignition method and the ignition timing are determined in advance, the ignition request voltage further increases due to aging and deterioration. Determine high load areas that are likely to be high and lead to misfire based on experimental or desktop calculations.

  It is well known that the internal combustion engine 1 has a higher oil viscosity at a lower temperature and tends to increase a torque required to start the engine, so that the air filling amount increases at a lower temperature. The more the pressure in the combustion chamber 1b at the ignition timing increases, the higher the required ignition voltage and the easier the misfire. In step S3 of FIG. 8, it is determined whether or not the internal combustion engine 1 is in a predetermined low temperature state and is being started. The temperature of the internal combustion engine 1 is detected by a water temperature sensor 17 that detects the cooling water temperature. Whether or not the internal combustion engine 1 is being started is determined from the operating state of the starter switch or the like.

  The cooling water temperature corresponding to the threshold value for determining the “predetermined low-temperature state” is further increased by the ignition request voltage due to aging and deterioration when the ignition method and the ignition timing are determined in advance. The cooling water temperature that is high and may cause misfire is determined based on experimental or desk trial results.

  Further, in step S4 of FIG. 8, it is determined whether or not the ignition timing determined based on the operating state of the internal combustion engine 1 is on the advance side of TDC and within a predetermined range from TDC. As described with reference to FIG. 5, the pressure in the combustion chamber at the ignition timing becomes higher as the ignition timing is advanced and closer to the TDC than the TDC, and the ignition request voltage becomes higher and the misfire is more likely to occur. Based.

  As for the ignition timing corresponding to the threshold value for determining that “it is within a predetermined range from TDC”, the ignition request voltage is determined by the ignition retard at the time of knock occurrence when the ignition method and the ignition timing are determined in advance. Taking into consideration that the required ignition voltage becomes higher due to aging and deterioration, it is determined based on experimental or desk trial calculation results.

  Further, in step S5 of FIG. 8, it is determined whether or not the phase difference of the ignition timing is greater than or equal to a predetermined value. However, as described with reference to FIG. This is based on the fact that the pressure in the combustion chamber at the ignition timing of the spark plug increases, and the ignition request voltage becomes high and misfire is likely to occur.

  It should be noted that the phase difference corresponding to the threshold value for determining that the “ignition timing phase difference is equal to or greater than a predetermined value” is also ignited due to aging and deterioration when the ignition method and the ignition timing are determined in advance. The required voltage is further increased, and a phase difference that may lead to misfire is determined based on experimental or desk trial results.

  Then, in step S6 of FIG. 8, each ignition coil is driven and controlled with the ignition sequence and ignition timing as stored in the memory in the ECU 2, and in step S7, as stored in the memory in the ECU 2. The ignition start order of each spark plug is limited so that the second spark plug 13b does not start discharging earlier than the first spark plug 13a. 14b is driven and controlled.

The ignition control device for an internal combustion engine according to the present invention has the following features.
According to the ignition control device for an internal combustion engine according to claim 1, the first spark plug disposed in the combustion chamber of the internal combustion engine and igniting the air-fuel mixture in the combustion chamber by the discharge in the plug gap, and the first spark plug Is disposed in the same combustion chamber as the combustion chamber in which is disposed, and an initial value of a plug gap narrower than the first spark plug is set, the first spark plug, and the second ignition An ignition control device for an internal combustion engine, comprising: an ignition control unit that controls a discharge operation and an ignition timing in each spark plug of the plug, wherein the ignition control unit includes the first ignition plug and the second ignition When the ignition of the air-fuel mixture is performed by discharge in both spark plugs of the plug, the first spark plug is prevented from starting discharge before the first spark plug. Ignition And the discharge start order of the second spark plug are limited, so that the operating state is prohibited in the prior art without increasing the power capacity of the ignition system, increasing the size of the ignition coil and increasing the cost. As a result, the ignition performance and the combustion state can be improved in a wider operating range than in the prior art. Further, when phase ignition is performed, it is possible to prevent the ignition request voltage in the spark plug to be discharged later from becoming too high, thereby avoiding a decrease in the life or damage of the spark plug.

  According to the ignition control device for an internal combustion engine according to claim 2, since the above-described restriction of the discharge start order is performed when the internal combustion engine is operating in a predetermined high load region, conventionally, the occurrence of misfire has occurred. Multipoint ignition can be executed even during `` high load operation of an internal combustion engine '' where it has been necessary to prohibit multipoint ignition to avoid ignition. Improved combustion conditions can be realized.

  According to the ignition control device for an internal combustion engine according to the third aspect, since the above-described restriction of the discharge start order is performed when the internal combustion engine is in a predetermined low temperature state and being started, conventionally, misfire has occurred. Multipoint ignition can be executed even at the time of `` low temperature start '' of an internal combustion engine that had to be prohibited to avoid multipoint ignition in order to avoid it, especially ignition performance and combustion state at low temperature start Can be improved.

  According to the ignition control device for an internal combustion engine according to claim 4, the discharge start sequence described above when the ignition timing determined based on the operating state of the internal combustion engine is on the advance side of TDC and within a predetermined range from TDC. Therefore, when performing phase ignition, in order to avoid the occurrence of misfire, conventionally, it was necessary to prohibit multipoint ignition. Multipoint ignition can be executed even when the engine is controlled within a predetermined range from the time point, particularly when the ignition timing is advanced from TDC and controlled within the predetermined range from TDC. Improvement of ignition performance and combustion state can be realized.

  According to the ignition control device for an internal combustion engine according to claim 5, the discharge start order is limited when the interval between the ignition timings of the first spark plug and the second spark plug is a predetermined value or more. Therefore, at the time of execution of phase ignition, even when “the interval of the ignition timing of the first spark plug and the second spark plug is controlled to be a predetermined value or more”, it becomes possible to execute multipoint ignition. In particular, the ignition required voltage in the spark plug to be discharged later is prevented from becoming too high and misfiring can be prevented, thereby improving the ignition performance and the combustion state.

  According to the ignition control device for an internal combustion engine according to claim 6, since the first spark plug is disposed at least near the center of the combustion chamber, at least one of the plurality of spark plugs is combusted. When arranged near the center of the chamber, the spark plug located near the center of the combustion chamber is the first spark plug defined in the present invention, and as a result, the first spark plug and the second When performing multi-point ignition control for limiting the discharge start sequence of the spark plug, as described in Patent Document 2 (paragraph [0064]), it is originally disposed near the center of the combustion chamber having good ignitability. The discharge by the other spark plug (that is, the spark plug designated as the first spark plug) is not started after the discharge by the other spark plug (the spark plug designated as the second spark plug). As a result, it is avoided that the ignition required voltage in the first spark plug disposed near the center of the combustion chamber becomes too high, and the first spark plug disposed near the center of the combustion chamber having good ignitability. It is possible to make the discharge due to the more reliable.

  As described above, the ignition control device for an internal combustion engine according to the present invention is useful for an ignition control device for an internal combustion engine that includes a plurality of spark plugs for one combustion chamber, and particularly in the combustion chamber at the ignition timing. It is possible to suppress misfire when the engine is operated under a condition where the pressure is high, and it is suitable for performing multipoint ignition in a wider operating range than in the prior art.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 1a Cylinder 1b Combustion chamber 1c Intake valve 1d Exhaust valve 1e Piston 1f Connecting rod 1g Crankshaft 1h Intake side camshaft 2 Engine control unit (ECU)
3 accelerator pedal 4 accelerator position sensor 5 intake passage 6 air cleaner 7 air flow sensor 8 electronic control throttle 8a throttle opening sensor 8b butterfly valve 8c motor 9 surge tank 10 cam angle sensor 11 fuel injection valve 12 crank angle sensor 13a first ignition plug 13b Second ignition plug 14a First ignition coil 14b Second ignition coil 15 Exhaust manifold 16 Catalyst 17 Water temperature sensor

Claims (5)

A first spark plug disposed in the combustion chamber of the internal combustion engine and igniting an air-fuel mixture in the combustion chamber by discharge in the plug gap;
A second spark plug that is disposed in the same combustion chamber as the combustion chamber in which the first spark plug is disposed and in which an initial value of a plug gap that is narrower than the first spark plug is set;
An ignition control unit that controls a discharge operation and an ignition timing in each of the first spark plug and the second spark plug;
An ignition control device for an internal combustion engine comprising:
The ignition control unit is configured to execute ignition of the air-fuel mixture by discharge in both the first spark plug and the second spark plug while the internal combustion engine is operating in a predetermined high load region. The discharge start order of the first spark plug and the second spark plug is limited so that the second spark plug does not start discharging earlier than the first spark plug. Engine ignition control device. 2. The ignition control device for an internal combustion engine according to claim 1 , wherein the ignition control unit limits the discharge start order when the internal combustion engine is in a predetermined low temperature state and is being started . The ignition control unit restricts the discharge start order when an ignition timing determined based on an operating state of the internal combustion engine is on an advance side of TDC and within a predetermined range from TDC. The ignition control device for an internal combustion engine according to claim 1 or 2 . The said ignition control part performs the restriction | limiting of the said discharge start order, when the space | interval of the ignition timing of the said 1st spark plug and the said 2nd spark plug is more than predetermined value. The internal combustion engine ignition control device according to any one of the above. Ignition control system for an internal combustion engine according to any one of claims 1 to 4, characterized in that a first spark plug near the center of the combustion chamber even without low.

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