JPH06272599A - Fuel ignition device for engine - Google Patents

Abstract

PURPOSE:To compensate deviation in air-fuel ratio upon intake even if atomization of fuel changes at a time so as to reduce torque shock by compensating fuel ignition amount according to the change direction of fuel ignition timing at the time of changing fuel ignition timing, and making variably the compensation amount according to at least one of fuel ignition timings just before and after the change. CONSTITUTION:When a fuel ignition timing to an engine is changed, fuel ignition amount is compensated according to the change direction of fuel injection timing. When the change is made to the side where fuel injection timing becomes early, the time until the fuel injected to an intake passage 8 from an injector 13 is supplied to a combustion chamber 7 in a cylinder 2 of the engine 1 becomes long, and atomized fuel which contributes combustion in the cylinder 2 during fuel ignition is increased so that the air-fuel ratio tend to shift to the rich side. In accordance with the change of fuel injection timing to the advance side fuel injection amount is compensated to the decrease side and dislocation of air-fuel ratio is cancelled. Irrespective of fuel injection timings before and after the change air-fuel ratio upon intake operation is maintained properly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine fuel injection device, and more particularly to an engine fuel injection device having a variable fuel injection timing.

[0002]

2. Description of the Related Art Conventionally, a fuel injection device adapted to change the fuel injection timing of this kind of engine is well known. For example, in the one disclosed in Japanese Patent Laid-Open No. 61-106946, steady operation of the engine is known. The fuel injection timing is changed depending on time and during transient operation such as acceleration, and during transient operation, the injection timing is closer to the intake stroke than during steady operation so as to compensate for the fuel supply response delay during transient operation. There is.

In addition to this, the fuel injection timing is changed according to the load state of the engine so that the fuel vaporization /
It is also known to set the injection timing away from the intake stroke to promote atomization, while in the high load range, to inject fuel at the injection timing near the intake stroke to improve intake charge efficiency. There is.

[0004]

By the way, as shown in the former conventional example, a part of the fuel injected and supplied to the intake passage of the engine adheres to the wall surface of the intake passage and the intake valve. A part of the adhered fuel remains in the intake passage without being supplied to the cylinder in the intake stroke, and is supplied to the cylinder together with a part of the fuel injected and supplied in the next intake stroke. Then, when the fuel injection timing is constant, the remaining fuel is supplied to the cylinder with a certain amount of delay, so that the amount of this delay and the newly injected fuel are balanced and supplied to the cylinder. The intake air-fuel ratio becomes constant.

However, when the fuel injection timing is changed, during the transition, the degree of vaporization / atomization of the fuel adhering to the wall surface of the intake passage changes and the air-fuel ratio temporarily deviates from the target air-fuel ratio. There is a problem that a torque shock of the engine occurs due to the deviation of the air-fuel ratio.

That is, when the fuel injection timing is advanced, the time until the fuel is supplied to the cylinder becomes longer, so during the injected fuel, vaporization / contribution that contributes to combustion in the cylinder is performed.
The atomized fuel increases and the air-fuel ratio shifts to the rich side. on the other hand,
On the contrary, when the fuel injection timing is retarded, the time until the fuel is supplied to the cylinder is shortened, so the vaporized / atomized fuel supplied to the cylinder is reduced, and the air-fuel ratio becomes leaner. It shifts.

The present invention has been made in view of the above points, and an object thereof is to control the fuel injection state at the time of changing the fuel injection timing so as to temporarily change the air-fuel ratio at the time of the change. It is to try to reduce the torque shock of the engine by compensating for the deviation.

[0008]

In order to achieve this object, according to the invention of claim 1, when the fuel injection timing is changed, correction is made to increase or decrease the fuel injection amount according to the direction of the change, and The correction amount is changed according to the injection timing before and after the change.

That is, according to the present invention, as shown in FIG. 1, in the fuel injection device for an engine provided with the injection timing changing means 24 for changing the fuel injection timing to the engine 1 according to various conditions, the injection timing change is performed. When the fuel injection timing is changed by the means 24, the fuel injection amount is corrected according to the changing direction of the fuel injection timing, and the fuel correction amount is made variable according to at least one of the fuel injection timing before and after the change. It is characterized in that the correction means 25 is provided.

According to the second aspect of the present invention, the injection amount correction means 25 is configured to reduce the fuel correction amount when the fuel injection timing before being changed by the injection timing changing means 24 is far from the intake stroke as compared to when it is near. To do.

In the third aspect of the invention, the injection amount correction means 25
When the fuel injection timing is changed to the side where the fuel injection timing is advanced by the injection timing changing means 24, the fuel injection amount is corrected to decrease.

On the other hand, in the invention of claim 4, the above-mentioned claim 3 is adopted.
Contrary to the above invention, it is assumed that the injection amount correction means 25 is configured to increase and correct the fuel injection amount when the injection timing changing means 24 changes the fuel injection timing to the side where the fuel injection timing is delayed.

[0013]

With the above construction, in the invention of claim 1, when the fuel injection timing is changed by the injection timing changing means 24, the fuel injection amount is adjusted by the injection amount correcting means 25 in accordance with the direction of change of the fuel injection timing. The correction amount is corrected and is changed according to at least one of the fuel injection timings before and after the change. Therefore, when the fuel injection timing is changed, even if the degree of vaporization / atomization of the fuel adhering to the wall surface of the intake passage is temporarily changed, the fuel is supplied into the cylinder regardless of the injection timing before and after the change. It is possible to prevent the air-fuel ratio of the intake air from deviating, maintain the air-fuel ratio appropriately, and reduce the torque shock of the engine 1 due to the deviation of the air-fuel ratio.

According to the second aspect of the invention, when the fuel injection timing before the change by the injection timing changing means 24 is far from the intake stroke, the fuel correction amount is changed by the injection quantity correcting means 25 to be smaller than when it is near. When the fuel injection timing is changed, the air-fuel ratio of the intake air can be appropriately maintained regardless of the injection timing before the change, and the same effect as that of the invention of claim 1 can be obtained.

In the invention of claim 3, the injection timing changing means 2
When the fuel injection timing is changed to the side in which the fuel injection timing is advanced by 4, the fuel injection amount is corrected by the injection amount correction means 25. That is, as the fuel injection timing is changed to the advance side, as described above, the time until the fuel is supplied to the cylinder becomes longer, and the vaporized / atomized fuel that contributes to combustion in the cylinder increases during the injected fuel. Then, the air-fuel ratio tries to shift to the rich side, but since the fuel injection amount is corrected to the reduction side accordingly, the correction to the reduction side cancels the deviation of the air-fuel ratio, and thus the air-fuel ratio is adjusted to the proper value. Can be kept at

Further, according to the fourth aspect of the invention, when the fuel injection timing is changed to the later side, the fuel injection amount is increased and corrected. That is, as the fuel injection timing is changed to the retard side, the time until the fuel is supplied to the cylinder is shortened, the vaporized / atomized fuel that contributes to combustion in the cylinder is reduced, and the air-fuel ratio is shifted to the lean side. Although the deviation tends to occur, the fuel injection amount is corrected to the increasing side accordingly, so that the deviation of the air-fuel ratio is offset and the air-fuel ratio can be maintained appropriately.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIG. FIG. 5 shows an overall configuration of an embodiment of the present invention. Reference numeral 1 denotes an engine in which a cylinder head 5 is assembled on an upper surface of a cylinder block 3 having a cylinder 2, and a piston 6 is reciprocally fitted in the cylinder 2. A combustion chamber 7 is formed in the cylinder 2 by being inserted and surrounded by the top surface of the piston 6 and the lower surface of the cylinder head 5.

Reference numeral 8 denotes an intake passage for supplying intake air to the combustion chamber 7, reference numeral 9 denotes an intake valve for opening and closing an opening end of the intake passage 8 to the combustion chamber 7, and the intake passage 8 is sucked in order from the upstream side. An air flow meter 10 that detects the amount of air, a throttle valve 11 that throttles the intake passage 8, a surge tank 12, and an injector 13 that injects fuel into the intake passage 8 are provided.

On the other hand, 14 is an exhaust passage for discharging the exhaust gas in the combustion chamber 7, and 15 is the combustion chamber 7 of the exhaust passage 14.
An exhaust valve that opens and closes an opening end of the exhaust gas, and a catalyst device 16 that purifies exhaust gas is disposed in the exhaust passage 14.

Reference numeral 17 is an ignition plug that ignites the intake air in the combustion chamber 7, and the ignition plug 17 is connected to an ignition coil 19 via a distributor 18. 20 is a water jacket 4 of the cylinder block 3
It is a water temperature sensor that detects the temperature of the cooling water inside.

The injector 13 receives a fuel injection signal from the control unit 21 and injects fuel, and the ignition coil 19 serves as the control unit 2.
In response to the ignition signal from No. 1, a high ignition voltage is supplied to the ignition plug 17. At least the intake air amount signal from the air flow meter 10, the crank angle signal from the distributor 18, and the water temperature signal from the water temperature sensor 20 are input to the control unit 21.

In the control unit 21 shown in FIG.
The air-fuel ratio control as shown in is executed. First, various signals are input in step S1, and in step S2, the engine load is set based on the intake air amount signal from the air flow meter 10 and the engine speed is set based on the crank angle signal from the distributor 18. The fuel injection amount is set by the fuel injection amount map, and the basic fuel injection timing is set by the fuel injection timing map in the subsequent step S3. In the next step S4, it is determined whether or not the conditions for switching and changing the fuel injection timing from the engine operating state such as the load, the rotation speed, and the cooling water temperature of the engine 1 are satisfied. If the determination is NO, the process returns. Yes
If so, the process proceeds to step S5, and it is determined whether the switching direction is the direction in which the fuel injection timing is advanced (advance direction). When the determination is "advance direction", YES, in step S6, the air-fuel ratio correction amount is read from the preset amount reduction correction map, and when the determination is "retard direction", NO, the preset increase amount is set in step S7. After reading the air-fuel ratio correction amount from the correction map, the process proceeds to step S8. Both the above-mentioned amount reduction and increase correction maps are set according to the basic position of the fuel injection timing and the cooling water temperature. In the amount reduction correction map, the basic position of the fuel injection timing is the intake stroke as shown in FIG. 3 (a). As the intake stroke approaches from the front side, the correction amount of the fuel injection amount from the injector 13 becomes smaller, the air-fuel ratio correction amount also becomes smaller, and the swing width (change amount of the injection timing) also becomes smaller. As shown in FIG. 4 (a), the air-fuel ratio correction amount is set to increase as the cooling water temperature rises. On the other hand, in the increase correction map, as shown in FIG. 3B, as the basic position of the fuel injection timing approaches the intake stroke from the front side of the intake stroke, the correction quantity of the fuel injection quantity becomes smaller and the air-fuel ratio correction quantity also becomes smaller. As it becomes smaller and its swing width (injection timing change amount) becomes smaller,
Further, as shown in FIG. 4 (b), the air-fuel ratio correction amount is set to be smaller as the cooling water temperature rises.

Then, in step S8, the air-fuel ratio is corrected by controlling the fuel injection amount from the injector 13 in accordance with the read air-fuel ratio correction amount only during the switched fuel injection timing. Then return.

In this embodiment, step S of the above flow is performed.
4, the injection timing changing means 24 is configured to change the fuel injection timing to the engine 1 from the basic injection timing according to various conditions.

Further, in steps S5 to S8, when the fuel injection timing is changed by the injection timing changing means 24, when the fuel injection timing is changed to an earlier side, the fuel injection amount is reduced and corrected, while the fuel injection timing is changed. The fuel injection amount (air-fuel ratio) is corrected according to the changing direction of the fuel injection timing so that the fuel injection amount is increased when the fuel injection amount is changed to the side where When the timing is far from the intake stroke, the injection amount correction means 25 is configured to be variable in accordance with the fuel injection timing before the change so as to be smaller when the timing is far from the intake stroke.

Therefore, in the above embodiment, when the fuel injection timing to the engine 1 is changed, the fuel injection amount is corrected according to the changing direction of the fuel injection timing. That is, when the fuel injection timing is changed to an earlier side,
It takes a longer time for the fuel injected from the injector 13 to the intake passage 8 to be supplied to the combustion chamber 7 in the cylinder 2 of the engine 1, and the vaporized / atomized fuel that contributes to combustion in the cylinder 2 during the injected fuel. And the air-fuel ratio tends to shift to the rich side. However, as the fuel injection timing is changed to the advance side, the reduction correction map is used and the fuel injection amount is corrected to the reduction side. Therefore, the correction to the reduction side cancels the deviation of the air-fuel ratio. The torque shock of the engine 1 can be reduced by keeping the air-fuel ratio proper.

At this time, the reduction correction amount of the fuel injection amount is changed according to the injection timing before the change and the injection timing change amount (swing range), and the further the fuel injection timing before the change is from the intake stroke, The smaller the injection timing change amount is, the smaller the correction amount is changed. Therefore, the air-fuel ratio of the intake air can be appropriately maintained regardless of the injection timing before the change and the change amount thereof.

Further, the reduction correction amount of the fuel injection amount can be changed according to the cooling water temperature of the engine 1. The lower the cooling water temperature is, the smaller the reduction correction amount is, and the rich degree of the air-fuel ratio is suppressed. That is, when the temperature of the cooling water is low, the vaporization / atomization rate of the injected fuel is lower and the rich degree of the air-fuel ratio is lower than that at the time of high temperature, and accordingly, the reduction correction amount of the fuel injection amount is made smaller, The air-fuel ratio can be maintained at an appropriate air-fuel ratio.

On the other hand, when the fuel injection timing is changed to the side where the fuel injection timing is delayed, on the other hand, from the injector 13 to the intake passage 8
The time until the fuel injected into the cylinder 2 is supplied to the cylinder 2 becomes short, and the vaporized / atomized fuel that contributes to combustion in the cylinder 2 decreases, and the air-fuel ratio tends to shift to the lean side. The fuel injection amount is corrected to the increasing side in accordance with the change of the injection timing to the retard side, and this correction cancels the deviation of the air-fuel ratio. Therefore, even at this time, the air-fuel ratio can be properly maintained.

At this time, as in the case of the above-described reduction correction, the increase correction amount of the fuel injection amount can be changed smaller as the injection timing before the change is farther from the intake stroke and the injection timing change amount is smaller. The air-fuel ratio of the intake air can be appropriately maintained regardless of the previous injection timing and its change amount.

Further, the increase correction amount of the fuel injection amount becomes larger as the cooling water temperature of the engine 1 becomes lower, and the rich degree of the air-fuel ratio is promoted. In other words, when the temperature of the cooling water is low, the vaporization / atomization rate of the injected fuel is lower and the degree of richness of the air-fuel ratio is lower than that at the time of high temperature. Therefore, by increasing the correction amount for increasing the fuel injection amount accordingly, The air-fuel ratio can be maintained at an appropriate air-fuel ratio.

In the above embodiment, when the fuel injection timing is changed, the correction amount of the fuel injection amount is variable according to the fuel injection timing before the change, but it may be variable according to the fuel injection timing after the change. Of course, the point is to make it variable according to at least one of the fuel injection timings before and after the change.

[0033]

As described above, according to the first aspect of the invention, in the engine fuel injection device in which the fuel injection timing is changed according to various conditions, when the fuel injection timing is changed, the fuel injection timing is changed. The fuel injection amount is corrected according to the changing direction of the fuel injection amount, and the correction amount is changed according to at least one of before and after changing the injection timing. Further, in the invention of claim 2, when the fuel injection timing before the change is far from the intake stroke, the correction amount is made smaller than when it is close. Therefore, according to these inventions, when the fuel injection timing is changed, even if the degree of vaporization / atomization of the fuel adhering to the intake passage wall surface or the like temporarily changes, regardless of the injection timing before and after the change, The air-fuel ratio of the intake air supplied into the cylinder can be maintained appropriately, and the torque shock of the engine due to the deviation of the air-fuel ratio can be reduced.

According to the third aspect of the present invention, when the fuel injection timing is changed to an earlier side, the fuel injection amount is corrected so as to be reduced, so that the air-fuel ratio tends to shift to the rich side. The air-fuel ratio can be appropriately maintained by preventing the fuel injection amount by correcting it toward the reduction amount side.

Further, according to the invention of claim 4, when the fuel injection timing is changed to the side where the fuel injection timing is delayed, the fuel injection amount is corrected to be increased, so that the air-fuel ratio tends to shift to the lean side. Can be prevented by the increase correction of the fuel injection amount, and the air-fuel ratio can be appropriately maintained.

[Brief description of drawings]

FIG. 1 is a configuration diagram of the present invention.

FIG. 2 is a flowchart showing an air-fuel ratio control operation in the control unit according to the embodiment of the present invention.

FIG. 3 is a characteristic diagram of a correction map of a fuel injection amount according to a fuel injection timing and its swing range.

FIG. 4 is a characteristic diagram of a correction map of the fuel injection amount according to the cooling water temperature of the engine.

FIG. 5 is an explanatory diagram showing the overall configuration of the embodiment.

[Explanation of symbols]

 1 engine 2 cylinder 8 intake passage 13 injector 21 control unit 24 injection timing changing means 25 injection amount correcting means

Claims (4)

[Claims] 1. A fuel injection device for an engine, comprising an injection timing changing means for changing a fuel injection timing to an engine according to various conditions, wherein the fuel injection timing is changed when the fuel injection timing is changed by the injection timing changing means. Fuel injection amount correction means for correcting the fuel injection amount according to the changing direction of the fuel injection amount and changing the fuel correction amount according to at least one of the fuel injection timings before and after the change. apparatus. 2. The fuel injection device for an engine according to claim 1, wherein the injection amount correction means makes the fuel correction amount smaller when the fuel injection timing before being changed by the injection timing changing means is far from the intake stroke than when it is near. A fuel injection device for an engine, which is configured to: 3. The fuel injection device for an engine according to claim 1, wherein the injection amount correction means corrects the fuel injection amount in a reduced amount when the injection timing changing means changes the fuel injection timing to an earlier side. A fuel injection device for an engine, which is configured. 4. The fuel injection device for an engine according to claim 1, wherein the injection amount correction means corrects the fuel injection amount by increasing when the fuel injection timing is changed to the side where the fuel injection timing is delayed. A fuel injection device for an engine, which is configured.