JP2007270658A - Cylinder injection spark ignition type internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cylinder injection spark ignition type internal combustion engine capable of realizing stable stratified combustion by sure ignition, by always properly controlling the ignition timing to fuel injection and a charging period of an ignition system performed before the ignition, while preventing complication of arithmetic processing and a circuit constitution. <P>SOLUTION: A mode changeover switch 27 is switched to a B terminal 27b in a stratified combustion mode of a spray guide. A transistor 26 is driven on the basis of an injection signal. Charging is started by making a primary current flow to a primary winding 23 simultaneously with the rising of the injection signal. A spark plug 6 is ignited by discharge voltage induced in a secondary winding 24 by cutting off the primary current synchronously with the trailing of the injection signal. Thus, an ignition coil 22 is charged over a fuel injection period, and the ignition is performed just after the fuel injection. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cylinder injection type spark ignition type internal combustion engine, and more particularly, to a cylinder injection type spark ignition type internal combustion engine that ignites and performs stratified combustion when fuel spray injected from a fuel injection valve passes through the vicinity of a spark plug. It is about the institution.

  In a cylinder injection type spark ignition internal combustion engine that directly injects fuel into the combustion chamber, for example, the fuel spray injected from the fuel injection valve in the compression stroke is transferred to the vicinity of the spark plug, and the vicinity of the theoretical air-fuel ratio is around the spark plug. In this way, stratified lean combustion can be performed by igniting at an extremely lean air-fuel ratio as a whole. There are various modes for transferring the fuel spray to the vicinity of the spark plug, and there is a type in which stratified combustion is established by a so-called spray guide type fuel spray transfer method.

  In the spray-guided in-cylinder spark-ignition internal combustion engine, a fuel injection valve is disposed substantially upright at the top of the combustion chamber, and an ignition plug is provided so that the electrode portion faces the vicinity of the injection hole of the fuel injection valve. And ignited when fuel spray from the fuel injection valve reaches the vicinity of the spark plug by its own kinetic energy to establish stratified combustion. Since the period during which the fuel spray passing through the vicinity of the spark plug can be ignited is very short, as shown in FIG. 3, regions of ignition timing SA and fuel injection timing IT where stable stratified combustion is established by the spray guide method (hereinafter referred to as combustion stability) (Referred to as a region) is quite narrow, and it is necessary to set the ignition timing during or immediately after fuel injection.

  Further, since the allowable range of the appropriate ignition timing is reduced as the fuel injection period is shortened from such characteristics, for example, even in a low load region where the injection period is shortened with a decrease in engine load, or the same injection amount. In the low rotation range where the fuel injection period converted to the crank angle is shortened as the rotation decreases, the allowable range of the ignition timing is inevitably narrowed. Therefore, there has been a problem that misfires are likely to occur outside the stable combustion region during transient operation in a low load region or a low rotation region.

In order to stabilize the combustion, measures to enrich the air-fuel ratio in the low load and low rotation range or to switch to uniform combustion can be considered, but all of them were not drastic measures because they caused fuel consumption deterioration. .
On the other hand, in a spray guide type internal combustion engine, various methods have been proposed to set an appropriate ignition timing with respect to the fuel injection timing IT (see, for example, Patent Document 1). In the technique of Patent Document 1, a delay time is set based on the operating state of the internal combustion engine, and ignition is performed after the delay time elapses from the end of the fuel injection period.
JP 60-125748 A

Although there is no description regarding the setting of the charging period of the ignition system in the technique of the above-mentioned Patent Document 1, for example, when charging is started with the end of the injection period as a trigger, even if the delay time elapses depending on the set delay time There is a possibility that a sufficient amount of charge cannot be obtained, and as a result, a problem of misfire due to lack of discharge energy occurs.
In addition, in order to ensure an appropriate charging period, it is conceivable to start charging by a predetermined dwell angle (= time required for charging the ignition coil) before the ignition timing. In addition, it is necessary to take a calculation procedure for determining the ignition timing from the delay time and determining the charge start timing that precedes the dwell angle from the ignition timing, which causes another problem of complicated processing.

In addition, the technique of Patent Document 1 has a problem that the configuration of the ignition system becomes complicated due to the addition of an igniter circuit for controlling the ignition timing.
The present invention has been made to solve such problems, and the object of the present invention is to prevent the calculation process and the circuit configuration from becoming complicated, and to precede the ignition timing and ignition for fuel injection. It is an object of the present invention to provide an in-cylinder injection spark ignition type internal combustion engine that can always properly control the charge period of the ignition system to be executed and can realize stable stratified combustion by reliable ignition.

  In order to achieve the above object, the invention of claim 1 includes a fuel injection valve that directly injects fuel into the combustion chamber, and an ignition plug having an electrode portion disposed in the vicinity of an injection path of fuel spray from the fuel injection valve. In a cylinder injection type spark ignition type internal combustion engine that ignites and stratifies combustion when fuel spray injected from the fuel injection valve in the compression stroke of the engine passes near the electrode part of the spark plug, it synchronizes with the rotation of the engine An injection control means for generating an injection signal at a predetermined timing and drivingly controlling the fuel injection valve based on the injection signal, a primary winding and a secondary winding, and using the injection signal as a primary current to the primary winding And an ignition current generating means for generating a high voltage current by the induction action of the secondary winding and supplying the spark plug to the spark plug when the primary current is cut off in synchronization with the end of fuel injection. is there.

  Therefore, in the compression stroke of the engine, the fuel injection valve is driven and controlled by the injection control means based on the injection signal to inject fuel, and the fuel spray passes near the electrode part of the spark plug. On the other hand, the injection signal is supplied as a primary current to the primary winding of the ignition current generating means and charged by the primary current during the fuel injection period, and the primary current is synchronized with the end of the fuel injection. When cut off, a high voltage current is generated in the secondary winding by an inductive action, and this high voltage current is supplied to the spark plug and ignited. As a result, the spark plug is ignited immediately after fuel injection. At this time, the fuel spray from the fuel injection valve is passing through the spark plug, so that the fuel spray is reliably ignited.

  Further, in the spray guide, if the injection period becomes longer, the flow velocity at the spark plug position increases and ignition becomes difficult. Therefore, as the engine load increases, a larger discharge energy is required at the time of ignition. Since the injection period, that is, the charging period by the primary current is also extended, the discharge energy of the spark plug increases with the amount of charge of the ignition current generating means. As a result, since ignition is performed with an appropriate discharge energy according to the engine load, misfire due to insufficient discharge energy, wear of the electrode portion due to excessive discharge energy, and the like can be avoided in advance.

Furthermore, since the optimum ignition timing and charging period described above are determined automatically once the fuel injection period (injection signal) is determined, these ignition timing and charging period can be determined without complicating the processing of the control device and the configuration of the ignition system. Optimal control can be realized based on the charging period.
According to a second aspect of the present invention, in the first aspect, in addition to the stratified combustion, the internal combustion engine can execute uniform combustion in which fuel is injected in the intake stroke to ignite a uniform mixture. The ignition signal generating means for generating an ignition signal at the time of uniform combustion based on the operating state of the engine, and the ignition signal of the ignition signal generating means and the injection signal of the injection control means are selectively configured to switch according to the operating region Switching means for supplying to the primary winding of the ignition current generating means, and switching control means for switching the switching means to the ignition signal side during uniform combustion and switching the switching means to the injection signal side during stratified combustion. is there.

  Therefore, at the time of uniform combustion of the engine, the switching means is switched to the ignition signal side by the switching control means, and the ignition signal generated by the ignition signal generating means is supplied to the primary winding of the ignition current generating means for ignition. . Further, at the time of stratified combustion of the engine, the switching means is switched to the injection signal side, and the injection signal generated by the injection control means is supplied to the primary winding of the ignition current generating means to perform ignition.

As described above, in the uniform combustion, since the ignition timing suitable for the uniform combustion different from the ignition timing based on the injection signal is applied, stable combustion is possible in both uniform combustion and stratified combustion.
According to a third aspect of the present invention, in the first aspect, the ignition signal generating means for generating an ignition signal at the time of stratified combustion based on the operating state of the engine, and the ignition signal of the ignition signal generating means and the injection signal of the injection control means are selected. Switching means for supplying to the primary winding of the ignition current generating means, and switching means to the ignition signal side in the region where the engine rotational speed or engine load is high in the operation region where stratified combustion is performed, and in the operation region Switching control means for switching the switching means to the injection signal side in a region where the engine rotational speed or engine load is low.

  Therefore, in a region where the engine speed or engine load in the stratified combustion operation region is high, the switching means is switched to the ignition signal side by the switching control means, and the ignition signal generated by the ignition signal generating means is It is supplied to the primary winding and ignited. In the region where the engine speed or engine load in the stratified combustion operation region is low, the switching means is switched to the injection signal side, and the injection signal generated by the injection control means is applied to the primary winding of the ignition current generating means. Supplied and ignited.

Particularly in the region where the engine speed and engine load are low, the range of the appropriate ignition timing is narrow and the combustion tends to become unstable. In such a region, ignition is performed with the optimal ignition timing and charging period based on the injection signal. Therefore, stable combustion is possible in the entire stratified combustion region.
The invention of claim 4 is the injection signal correction according to claims 1 to 3, wherein the injection signal period is corrected in accordance with the operating state of the engine and the corrected injection signal is supplied to the primary winding of the ignition current generating means. Means are provided.

  Accordingly, the corrected injection signal is supplied to the primary winding of the ignition current generating means in accordance with the operating state of the engine, and ignition is performed. For example, the charging period of the ignition current generating means is too short in the low load range and the discharge energy is insufficient. In the high load range, the charging period is too long and the discharge energy is excessive, but the injection signal correction means As a result of this correction, the charging period of the ignition current generating means is always optimally controlled regardless of the engine load, thereby preventing misfire due to insufficient discharge energy or wear of the electrode portion of the spark plug due to excessive discharge energy. .

According to a fifth aspect of the present invention, in the fourth aspect, the fuel injection valve is configured to be capable of adjusting an injection amount per hour, and is provided with an injection amount correcting means for correcting the injection amount per hour of the fuel injection valve. is there.
Therefore, by correcting the injection amount per time of the fuel injection valve by the injection amount correcting means, the variation in the fuel injection amount that occurs with the correction of the injection signal is compensated.

As described above, according to the in-cylinder injection spark ignition internal combustion engine of the first aspect of the present invention, the calculation process and the circuit configuration are prevented from being complicated, and the ignition timing and the ignition for the fuel injection are executed prior to the ignition. Therefore, the charging period of the ignition system can be controlled appropriately at all times, and stable stratified combustion can be realized by reliable ignition.
According to the cylinder injection type spark ignition internal combustion engine of the invention of claim 2, in addition to claim 1, stable combustion can be realized not only in stratified combustion but also in uniform combustion.

According to the in-cylinder injection type spark ignition type internal combustion engine of the invention of claim 3, in addition to claim 1, in the region where the engine rotational speed or the engine load is low, especially in the region of stratified combustion, the combustion is likely to be unstable. Stable stratified combustion can be realized by reliable ignition.
According to the in-cylinder injection type spark ignition internal combustion engine of the invention of claim 4, in addition to claims 1 to 3, the charging period of the ignition current generating means is always optimally controlled regardless of the engine load, and the discharge energy is controlled. Misfire due to shortage and wear of the electrode portion of the spark plug due to excessive discharge energy can be prevented in advance.

  According to the in-cylinder injection type spark ignition internal combustion engine of the fifth aspect of the invention, in addition to the fourth aspect of the invention, the variation of the fuel injection amount accompanying the correction of the injection signal is compensated, and an appropriate fuel corresponding to the operating state is compensated. The injection amount can be maintained.

[First Embodiment]
Hereinafter, a first embodiment of an in-cylinder injection spark ignition internal combustion engine embodying the present invention will be described.
FIG. 1 is a schematic configuration diagram showing an in-cylinder injection spark ignition type internal combustion engine of the present embodiment. The internal combustion engine E of the present embodiment is configured as an in-line four-cylinder engine, and each figure shows one cylinder, but the other cylinders have the same configuration.

  A piston 2 is slidable in a vertical direction in a cylinder 1 a formed in a cylinder block 1 of the internal combustion engine E, and a cylinder head 3 is fixed on the cylinder block 1. A pair of inclined surfaces 3a and 3b are formed on the lower surface of the cylinder head 3 so as to incline toward the intake side (left side in the figure) and the exhaust side (right side in the figure) of the internal combustion engine E. A so-called pent roof type combustion chamber 4 is formed by being surrounded by 3b, the inner wall of the cylinder 1a, and the top surface of the piston 2.

  A fuel injection valve 5 is provided at a position slightly on the intake side from the ridge line where both the inclined surfaces 3a and 3b of the cylinder head 3 intersect, and the fuel injection valve 5 is held in an upright posture with its upper end slightly inclined toward the intake side. The injection hole 5 a provided at the lower end faces the combustion chamber 4 and fuel can be injected into the combustion chamber 4. An ignition plug 6 is disposed at a position slightly on the exhaust side from the ridge lines of the both inclined surfaces 3a and 3b of the cylinder head 3, and the ignition plug 6 is held in an upright posture with its upper end slightly inclined toward the exhaust side. The lower electrode portion 6a faces the combustion chamber 4.

  As a result of the positional relationship between the fuel injection valve 5 and the ignition plug 6, the injection hole 5 a of the fuel injection valve 5 and the electrode part 6 a of the ignition plug 6 are close to each other in the combustion chamber 4. The fuel spray injected from the part 5a passes through the vicinity (directly below) of the electrode part 6a. The positional relationship between the fuel spray transfer path and the electrode portion 6a is not limited to this, and can be arbitrarily changed as long as the fuel spray can be transferred by a spray guide method described later. For example, the fuel spray transfer path May coincide with the electrode portion 6a.

  A pair of intake ports 7 are provided on the inclined surface 3 a on the intake side of the cylinder head 3 in the front-rear direction of the internal combustion engine E (a direction orthogonal to the paper surface) with the fuel injection valve 5 interposed therebetween. A pair of exhaust ports 8 are provided on the side slope 3b in the front-rear direction with the spark plug 6 interposed therebetween. Both intake ports 7 are provided with intake valves 7a, and both exhaust ports 8 are provided with exhaust valves 8a. These intake valves 7a and exhaust valves 8a are provided by a valve mechanism (not shown) on the cylinder head 3. It is opened and closed at a predetermined timing synchronized with the rotation of the crankshaft.

  Both intake ports 7 communicate with a common intake passage (not shown) together with intake ports of other cylinders. During engine operation, the intake air introduced into the intake passage is adjusted in flow rate according to the opening of the throttle valve, and then is supplied to each cylinder. It is distributed and flows into the combustion chamber 4 as the intake valve 7a is opened. Both exhaust ports 8 communicate with a common exhaust passage (not shown) together with the exhaust ports of the other cylinders. During engine operation, exhaust gas after combustion in the combustion chamber 4 enters the exhaust passage as the exhaust valve 8a is opened. Are discharged and merged with the exhaust gas of the other cylinders, and are discharged to the outside through a catalyst and a silencer provided in the exhaust passage.

  In the vehicle compartment, an input / output device (not shown), a storage device (ROM, RAM, etc.) used for storing control programs and control maps, a central processing unit 11a (CPU, shown in FIG. 2 described later), a timer An ECU (electronic control unit) 11 having a counter and the like is installed. On the input side of the ECU 11, there are various types such as a rotational speed sensor 12 that detects the rotational speed Ne of the internal combustion engine E, a throttle sensor 13 that detects the throttle opening θth of the internal combustion engine E, and an accelerator sensor 14 that detects the accelerator operation amount θacc. Sensors are connected, and various devices such as the fuel injection valve 5 and the spark plug 6 are connected to the output side.

FIG. 2 is a diagram showing a circuit configuration of the fuel injection system and the ignition system.
The fuel injection valve 5 is connected to the CPU 11a in the ECU 11 via a drive circuit 21, and the fuel injection valve 5 is opened by the drive circuit 21 in accordance with a drive signal output from the CPU 11a and burns during the valve opening period. Fuel injection into the chamber 4 is performed. The ignition plug 6 is connected to the CPU 11a via an ignition coil 22. One end of the primary winding 23 and the secondary winding 24 of the ignition coil 22 is connected to the CPU 11a, and a battery 25 mounted on the vehicle is connected between the CPU 11a and the primary winding 23. The other end of the secondary winding 24 is connected to the center electrode side of the electrode portion 6a of the spark plug 6, and the external electrode side of the electrode portion 6a is grounded.

  The other end of the primary winding 23 is connected to the collector of the transistor 26, and the emitter of the transistor 26 is grounded. When the transistor 26 is turned on by applying a voltage to the base, a primary current flows through the primary winding 23 of the ignition coil 22 and charging is started. When the voltage application to the base is interrupted and the transistor 26 is turned off, a high voltage is generated in the secondary winding 24 of the ignition coil 22 by inductive action due to the interruption of the primary current, and this high voltage is ignited. A spark discharge is generated in the electrode portion 6a by being supplied to the plug 5 (ignition current generating means).

  The base of the transistor 26 is connected to a mode changeover switch 27 (switching means). The mode changeover switch 27 receives a mode changeover signal from the CPU 11a, and the A terminal 27a connected to the output terminal of the ignition signal of the CPU 11a or the CPU 11a. Is selectively switched to one of the B terminals 27b connected between the drive circuit 21 and the drive circuit 21 (switching control means). Therefore, when the mode switch 27 is switched to the A terminal 27a side, the ignition signal output from the CPU 11a is applied to the base of the transistor 26, and when the mode switch 27 is switched to the B terminal 27b side, it is output from the CPU 11a. The injection signal is applied to the base of transistor 26.

  On the other hand, the CPU 11a determines the fuel injection amount Q, the injection timing IT from the engine speed Ne, the target average effective pressure Pe (engine load), the fuel pressure, etc., based on the preset fuel injection amount map, fuel injection timing map, and ignition timing map. And the ignition timing SA is set, and the fuel injection valve 5 and the spark plug 6 are controlled based on these target values. Further, the CPU 11a switches the operation mode of the internal combustion engine E between the uniform combustion mode and the stratified combustion mode according to the operation state. Specifically, the target average effective pressure is determined from the throttle opening θth and the engine rotational speed Ne. Pe is obtained, and an operation mode to be executed is determined according to a preset map from the target average effective pressure Pe and the engine speed Ne. The uniform combustion mode is an operation mode that is executed in an operation region in which the target average effective pressure Pe or the engine speed Ne is relatively high, and forms a uniform mixture with the fuel injected in the intake stroke to burn (uniform combustion). The stratified combustion mode is executed in a relatively low point low load region, and an air-fuel mixture near the stoichiometric air-fuel ratio is formed around the electrode portion 6a of the spark plug 6 by the fuel injected in the compression stroke. This is an operation mode in which combustion (stratified combustion) is performed at a low air-fuel ratio.

In this embodiment, a spray-guided fuel spray transfer method is applied to establish stratified combustion. That is, the fuel spray injected from the fuel injection valve 5 in the compression stroke passes directly under the electrode portion 6a of the spark plug 6 by its own kinetic energy, and the spark plug 6 is moved at a timing in accordance with the passage of the fuel spray at this time. It is ignited and stratified combustion is performed.
FIG. 3 shows a combustion stable region in which stable stratified combustion can be established by a spray guide method on the premise of a certain air-fuel ratio, and the periphery of the combustion stable region is a misfire region where combustion is not possible or combustion is incomplete. Since the period during which the fuel spray passing through the vicinity of the spark plug 6 can be ignited is very short, the spray-guided combustion stable region is considerably narrow as shown in the figure, and the operation in the combustion stable region is premised on a certain fuel injection timing IT. The feasible ignition timing SA is limited to the injection period and the vicinity immediately after it.

Next, the operation state of the direct injection spark ignition type internal combustion engine of the present embodiment configured as described above, particularly the control of the fuel injection timing IT and the ignition timing SA according to the operation mode will be described.
In the operation region of the uniform combustion mode, the CPU 11a selects the uniform combustion mode as the operation mode, and the mode changeover switch 27 is switched to the A terminal 27a. For the uniform combustion mode, target values of the injection timing IT and the ignition timing SA are set in advance as a map in accordance with the target average effective pressure Pe and the engine rotational speed Ne. Based on these target values, the injection signal and An ignition signal is generated, and these injection signal and ignition signal are output (ignition signal generation means). In the present embodiment, the injection timing IT is set as the injection end timing, the timing preceding the fuel injection amount Q with respect to the injection timing IT is set as the rising timing of the injection signal, and the injection timing IT is set as the rising timing of the injection signal. Although the lowering time is set, for example, the injection time IT may be set as the injection start time.

  Although the control in the uniform combustion mode is general and will not be described in detail, the fuel injection valve 5 is opened by the drive circuit 21 in synchronism with the ON period of the injection signal, and fuel injection is performed. A voltage is applied to the base of the transistor 26 of the ignition coil 22 in synchronism with the on period of the signal to charge the ignition coil 22, and the transistor 26 is turned off at the end of the on period to interrupt the primary current and the secondary winding. The spark plug 6 is ignited by the high-voltage current induced in 24. Due to the fuel injection and ignition executed in this way, the uniform air-fuel mixture formed by the intake stroke injection is ignited, and the internal combustion engine E is operated by uniform combustion.

  In the operation region of the stratified combustion mode, the stratified combustion mode is selected as the operation mode by the CPU 11a, and the mode changeover switch 27 is switched to the B terminal 27b. For the stratified combustion mode, the target value of the injection timing IT is set in advance as a map, but the map of the ignition timing SA is not set. The CPU 11a uses the injection timing IT and the fuel injection amount Q read from the map. An injection signal is generated and only this injection signal is output. Accordingly, fuel injection is performed in the same manner as in the uniform combustion mode, and the fuel injection valve 5 is driven by the drive circuit 21 in synchronization with the ON period of the injection signal (injection control means).

  Further, when the mode changeover switch 27 is switched to the B terminal 27b, the injection signal is applied to the base of the transistor 26 of the ignition coil 22. In this stratified combustion mode, ignition is performed based on the injection signal instead of the ignition signal in the uniform combustion mode. Executed. That is, as shown in the time chart of FIG. 4 showing the operating state of the ignition coil 22 with respect to the injection signal, as the injection signal rises, the primary current flows through the primary winding 23 to start charging, and the injection signal falls. Synchronously, the primary current is cut off and a high voltage is induced in the secondary winding 24. Therefore, charging of the ignition coil 22 is performed corresponding to the fuel injection period T, and ignition is performed immediately after the end of fuel injection (for example, point A in FIG. 3). The fuel spray injected from the fuel injection valve 5 is ignited by the fuel injection and ignition executed in this way, and the internal combustion engine E is operated by stratified combustion.

The above ignition timing control during stratified combustion is based on the following viewpoint.
As described above, the spray guide for igniting the fuel spray passing through the spark plug 6 has a narrow combustion stable region, and requires a more appropriate setting of the ignition timing SA compared with the case of uniform combustion. The setting of the ignition timing SA by the spray guide type is limited to the injection period in which the fuel spray passes in the vicinity of the electrode portion 6a of the spark plug 6, but it is desirable to discharge immediately after the end of the injection for the following reason. As described above, the present embodiment, in which ignition is performed immediately after the end of fuel injection, is an advantageous ignition timing setting from this point of view.
1) During the fuel injection period T, there is a high possibility that the fuel spray collides with the electrode portion 6a of the spark plug 6 and wet misfire occurs.
2) During the fuel injection period T, since the flow rate of the fuel spray at the gap position of the electrode portion 6a is high, there is a high possibility that the ignition arc is caused to flow or disappear.
3) It is necessary to ensure a period of vaporization of fuel spray and an appropriate diffusion, and this factor results in operation in the vicinity of MBT (Minimum advance for the Best Torque).
And so on.

If the discharge energy at the time of ignition is increased, the deterioration of the ignition conditions such as 1) and 2) described above can be dealt with to some extent, but this causes problems such as an increase in the cost of the ignition system and the consumption of the electrode portion 6a of the spark plug 6. It is hard to say that this is a drastic measure.
Moreover, as a requirement regarding the charging period (ignition dwell angle) of the ignition coil 22,
4) In the spray guide, the discharge energy required at the time of ignition tends to increase as the engine load increases, so it is desirable to extend the charging period of the primary winding 23 accordingly.

  Accordingly, when ignition is performed immediately after fuel injection by the ignition timing control synchronized with the above-described injection signal, the gas flow rate of fuel spray in the electrode portion 6a has already started to decrease as shown in FIG. The phenomenon of wet misfire due to the collision of the fuel spray on the electrode part 6a of requirement 1) and the phenomenon of the ignition arc flowing or disappearing of requirement 2) are prevented in advance. Further, since the vaporization and diffusion of the fuel spray are sufficiently promoted immediately after the fuel injection, the requirement 3) is sufficiently satisfied. Therefore, the spark plug 6 is always ignited at an appropriate timing in any operating region of the stratified combustion mode, and the fuel spray can be reliably ignited even during a transient operation in which the engine rotational speed Ne changes suddenly. Can be realized.

  In addition, since the fuel injection amount set by the fuel injection control increases as the engine load increases, in the stratified combustion mode, the charging period of the ignition coil 22 is extended along with the injection period T (injection signal ON period) in the higher load range. As a result, the amount of charge of the ignition coil 22, and thus the discharge energy of the spark plug 6 during ignition, also increases. Therefore, in the low load range where high discharge energy is not particularly required in the operation region of the stratified combustion mode, the charging period of the ignition coil 22 is shortened together with the injection period T, so that the discharge energy of the spark plug 6 at the time of ignition is reduced. As a result, the unnecessary consumption of the spark plug 6 can be suppressed. As a result, misfire caused by the consumed spark plug 6 can be prevented and the replacement interval of the spark plug 6 can be extended. On the other hand, in a high load range that requires high discharge energy, the charging period of the ignition coil 22 is extended together with the injection period T, so that the fuel spray can be reliably ignited by increasing the discharge energy. Contributes to stable combustion.

In addition, by variably controlling the charging period of the ignition coil 22, for example, the total power consumption required for ignition can be reduced as compared with general ignition timing control in which the charging period is constant. Therefore, the capacities of the ignition coil 22, the battery 25, the alternator, etc. can be reduced, and cost reduction can be achieved.
As described above, the ignition timing SA and the charging period of the ignition coil are always appropriately controlled. Moreover, if the injection signal is determined, the ignition timing SA (fall of the injection signal) and the charging period (on period of the injection signal) are naturally determined. Therefore, optimal control can be realized without complicating the processing of the control device and the configuration of the ignition system.

Furthermore, according to the setting method of the present embodiment in which the ignition timing SA is determined based on the injection signal, the following great advantages are obtained with respect to the prior matching for control.
That is, in the spray-guided stratified combustion, the relationship between the injection timing IT at which the fuel spray is injected for ignition of the fuel spray and the ignition timing SA at which the injected fuel spray is ignited is important. In such a setting method, it is necessary to carefully perform mutual matching between the injection timing IT and the ignition timing SA as well as individual matching. In addition, the operating point defined by the injection timing IT and the ignition timing SA is not only set in the combustion stable region of FIG. 3, but the operating point is set in the combustion stable region in anticipation of a control error of the ignition timing SA caused by a disturbance or the like. It is necessary to set the vicinity of the center of the engine (for example, point B in FIG. 3), and for this purpose, a detailed investigation of the combustion stable region is required for each operation region (for example, for each air-fuel ratio). Due to these factors, the conventional method requires enormous man-hours for prior matching.

On the other hand, in the present embodiment, the optimal ignition timing SA is automatically determined by setting the injection timing IT. Therefore, matching with respect to the ignition timing SA can be omitted, and there is no need to consider a control error of the ignition timing SA. Therefore, there is an excellent effect that the prior matching work can be greatly simplified.
[Second Embodiment]
Next, a second embodiment of a direct injection spark ignition type internal combustion engine embodying the present invention will be described.

The overall configuration of the internal combustion engine of the present embodiment is the same as that of the first embodiment shown in FIGS. 1 and 2, and the difference is in the setting of the fuel injection period T. Therefore, the description of the parts having the same configuration is omitted, and the differences are mainly described.
Although not shown, the fuel injection valve 5 of the present embodiment is configured to be able to adjust the injection amount per unit time by varying the lift amount of the needle valve for injection control. The storage device in the ECU 11 stores a correction coefficient for the injection period T (on period of the injection signal) and a correction coefficient for the lift amount of the needle valve corresponding to the target average effective pressure Pe (engine load) as a map. Yes. The correction coefficient for the injection period T is set to a characteristic for correcting the decrease in the injection period T as the target average effective pressure Pe increases, and the correction coefficient for the lift amount is set to a characteristic for correcting the lift amount to increase as the target average effective pressure Pe increases. Yes. By correction based on these correction coefficients, for example, as shown in the time chart of FIG. 6, the injection period T is extended and the lift amount is reduced as shown by the broken line in the low load region, and the solid amount is shown in the high load region. In addition, the injection period T is shortened and the lift amount is increased.

  The correction for the injection period T is a process for optimizing the charging period of the ignition coil 22. That is, if the charging period of the ignition coil 22 is completely matched to the injection period T as in the first embodiment, an appropriate charging period may not be achieved in a low load region or a high load region. Specifically, in the low load range, the charging period is too short and the discharge energy may be insufficient. In the high load range, the charging period may be too long and the discharge energy may be excessive. Regardless of the load, it is always controlled to the optimum charging period (injection period T) (injection signal correcting means).

  Further, the correction for the lift amount is for compensating for the fluctuation of the fuel injection amount Q accompanying the correction of the injection period T. In the low load region, the increase in the fuel injection amount Q accompanying the extension of the injection period T is lifted. Suppressed by reducing the amount of fuel (decreasing the injection amount per hour), and reducing the fuel injection amount Q accompanying the shortening of the injection period T by increasing the lift amount (increasing the injection amount per hour) in the high load range (Injection amount correcting means).

Therefore, by executing the above correction, the fuel injection amount Q corresponding to the operating state (Pe, Ne) is always maintained, and the charging period (ignition dwell angle) of the ignition coil 22 is set regardless of the engine load. It can be controlled to an optimum value, so that misfire due to lack of discharge energy and consumption of the electrode portion due to excessive discharge energy can be avoided in advance.
The injection signal after correction for the injection period T may be supplied to the B terminal 27b of the mode changeover switch 27 in a system different from the injection signal input to the drive circuit 21. In this case, fuel injection is performed. Correction for the lift amount of the valve 5 can be omitted.

  This is the end of the description of the embodiment, but the aspect of the present invention is not limited to this embodiment. For example, in the above-described embodiment, only the spray guide type is executed as the stratified combustion mode. However, in addition to the spray guide type, an internal combustion engine capable of performing so-called wall guide type stratified combustion that transfers fuel spray using intake air flow. The ignition timing control based on the injection signal of the above embodiment may be executed during stratified combustion in the spray guide.

In the above embodiment, the present invention has been embodied in an internal combustion engine that can switch between the uniform combustion mode and the stratified combustion mode by the spray guide. However, it is not always necessary to execute the uniform combustion mode. You may make it perform stratified combustion.
In the above embodiment, the ignition timing control based on the injection signal is executed in the entire area of the spray guide. However, for example, the application of the control is limited to a partial area, and the general ignition timing control is applied to the other areas. You may do it. That is, the operation region of the stratified combustion mode is divided into a high rotation high load region and a low rotation low load region, and the ignition timing SA is set as a target value for the high rotation high load region as in the uniform combustion mode. In this region, the mode changeover switch 27 is switched to the A terminal 27a side in FIG. 2 (switching control means), and an ignition signal generated from the ignition timing SA is output from the CPU 11a (ignition signal generating means). The transistor 26 is driven based on the signal. For the low rotation and low load range, the ignition timing control based on the injection signal is performed by switching the mode selector switch to the B terminal 26b side as in the above embodiment. If comprised in this way, the stable stratified combustion can be implement | achieved by reliable ignition especially in the low rotation low load area | region where combustion tends to become unstable also in the area | region of stratified combustion.

It is a schematic block diagram which shows the cylinder injection type spark ignition type internal combustion engine of 1st and 2nd embodiment. It is a figure which shows the circuit structure of a fuel-injection system and an ignition system. It is a figure which shows the combustion stable area | region by spray-stratified stratified combustion. It is a time chart which shows the operating condition of the ignition coil with respect to the injection signal in a stratified combustion mode. It is a time chart which shows the relationship between an injection signal and the gas flow rate of an electrode part. It is a time chart which shows the setting condition of the injection period of 2nd Embodiment, and the lift amount of a needle valve.

Explanation of symbols

4 Combustion chamber 5 Fuel injection valve 6 Spark plug 6a Electrode 11a CPU (Injection control means, ignition signal generating means, switching control means,
Injection signal correction means, injection amount correction means)
21 Drive circuit (injection control means)
22 Ignition coil (ignition current generating means)
23 Primary winding 24 Secondary winding 27 Mode selector switch (switching means)
E Internal combustion engine

Claims (5)

A fuel injection valve for directly injecting fuel into the combustion chamber and an ignition plug having an electrode portion disposed in the vicinity of an injection path of fuel spray from the fuel injection valve are injected from the fuel injection valve in the compression stroke of the engine. In-cylinder injection spark ignition internal combustion engine that ignites and stratifies combustion when the fuel spray passes near the electrode portion of the spark plug,
Injection control means for generating an injection signal at a predetermined timing synchronized with the rotation of the engine, and for driving and controlling the fuel injection valve based on the injection signal;
A primary winding and a secondary winding, when the injection signal is supplied to the primary winding as a primary current, and the primary current is cut off in synchronization with the end of the fuel injection; An in-cylinder injection spark ignition type internal combustion engine comprising: an ignition current generating means for generating a high-voltage current by the induction action of the secondary winding and supplying the high-voltage current to the spark plug. In addition to the stratified combustion, the engine is capable of performing uniform combustion in which fuel is injected during the intake stroke to ignite a uniform mixture, and is configured to switch between the uniform combustion and the stratified combustion according to the operating region. ,
Ignition signal generating means for generating an ignition signal at the time of uniform combustion based on the operating state of the engine;
Switching means for selectively supplying the ignition signal of the ignition signal generating means and the injection signal of the injection control means to the primary winding of the ignition current generating means;
The in-cylinder injection spark according to claim 1, further comprising: a switching control means for switching the switching means to the ignition signal side during the uniform combustion and switching the switching means to the injection signal side during the stratified combustion. Ignition internal combustion engine. Ignition signal generating means for generating an ignition signal at the time of stratified combustion based on the operating state of the engine;
Switching means for selectively supplying the ignition signal of the ignition signal generating means and the injection signal of the injection control means to the primary winding of the ignition current generating means;
The switching means is switched to the ignition signal side in a region where the engine rotational speed or engine load in the operating region where the stratified combustion is performed is high, and the switching means is switched in the region where the engine rotational speed or engine load is low in the operating region. 2. A direct injection spark ignition type internal combustion engine according to claim 1, further comprising switching control means for switching to the injection signal side.   2. An injection signal correcting means for correcting a period of the injection signal in accordance with an operating state of the engine and supplying the corrected injection signal to a primary winding of the ignition current generating means. The in-cylinder injection spark ignition internal combustion engine according to any one of 1 to 3. The fuel injection valve is configured to be capable of adjusting the injection amount per hour,
2. An injection amount correcting means for correcting an injection amount per time of the fuel injection valve in order to compensate for a variation in the fuel injection amount accompanying the correction of the injection signal by the injection signal correcting means. 4. An in-cylinder injection spark ignition type internal combustion engine as set forth in claim 4.

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