JP2012036757A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine which can restrict adhesion of fuel to an inner wall surface of a cylinder by appropriately distributing the fuel to be injected to a central part and peripheral parts of a combustion chamber.SOLUTION: Each cylinder of an engine 10 includes: two intake ports 20A and 20B respectively formed of a straight port; and fuel injection valves 24A and 24B set to spray the fuel asymmetrically against center axes L1 and L2. In fuel injection, among the fuel to be injected from the fuel injection valves 24A and 24B, the central region injection amount to be injected between stems 32A and 32B of intake valves 28A and 28B is set to be larger than the outside region injection amount to be injected outside of the stems 32A and 32B. With this structure, the fuel to be injected can be appropriately distributed to the central part inside of the cylinder and inner and outer peripheries of the cylinder in response to the air amount in each part inside of the cylinder. Further, the injected fuel which flows into inner and outer peripheries of the cylinder can be reduced to restrict the fuel adhesion amount to the inner wall surface of the cylinder.

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly to a control device for an internal combustion engine provided with a plurality of intake ports in one cylinder.

  As a conventional technique, for example, as disclosed in Japanese Patent Application Laid-Open No. 2007-262995, a control device for an internal combustion engine is known in which fuel injection valves are arranged in two intake ports, respectively. In the prior art, the cross-sectional shape of the fuel spray is set to a C shape by devising the pattern of the injection holes of each fuel injection valve. As a result, in the prior art, the injected fuel is prevented from adhering to the stem of the intake valve.

JP 2007-26295 A JP 2007-292058 A Japanese Patent Laid-Open No. 03-194148 JP-A-61-83459 JP 2009-216044 A JP 2006-299945 A

  In the above-described conventional technology, the fuel injected from the fuel injection valve is supplied to the central portion (inner peripheral portion) and the outer peripheral portion of the combustion chamber. However, in this configuration, since substantially the same amount of fuel is supplied to the central portion and the outer peripheral portion of the combustion chamber, the injected fuel is cylinder-filled at the outer peripheral portion having a relatively small space volume (air amount) as viewed from the fuel injection valve side. It becomes easy to adhere to the inner wall surface. For this reason, in the prior art, there is a problem that the amount of fuel adhering to the inner wall surface of the cylinder increases and fuel consumption and exhaust emission deteriorate.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to appropriately distribute the injected fuel to the central portion and the outer peripheral portion of the combustion chamber, and to fuel the inner wall surface of the cylinder. An object of the present invention is to provide a control device for an internal combustion engine capable of suppressing adhesion.

1st invention is formed as a straight port which each extends in a straight line and opens to a combustion chamber, and two intake ports arranged so that a central axis passes through one side and the other side with respect to the center of the combustion chamber When,
Two intake valves respectively provided on the two intake ports, each having an umbrella portion that opens and closes an opening portion of the intake port and a stem that supports the umbrella portion at a central position;
Two fuel injection valves that are respectively provided in the two intake ports and inject fuel toward the opening of the intake port on the central axis of each intake port;
Each fuel injection valve is configured to inject fuel into a central region located between the stems of the two intake valves and an outer region located outside the stems, respectively.
In at least one of the fuel injection valves, the central region injection amount that is the amount of fuel injected into the central region is set to be larger than the outer region injection amount that is the amount of fuel injected into the outer region. It is characterized by.

  According to the second invention, each of the fuel injection valves is configured such that the cross-sectional shape of the spray obtained by breaking the fuel spray along a plane perpendicular to the injection direction is C-shaped, and is provided in the cross-sectional shape of the spray. In addition, a single notch is configured to match the position of the stem.

According to a third invention, each of the fuel injection valves is constituted by an injection hole variable type injection valve capable of changing a ratio between the central region injection amount and the outer region injection amount,
Air amount correspondence control means for increasing the ratio of the outer region injection amount to the central region injection amount as the intake air amount increases.

According to a fourth invention, each of the fuel injection valves is constituted by an injection hole variable type injection valve capable of changing a ratio between the central region injection amount and the outer region injection amount,
Rotational speed corresponding control means for increasing the ratio of the outer region injection amount to the central region injection amount as the engine speed is higher is provided.

  According to a fifth aspect of the present invention, there is provided an injection timing control for executing fuel injection near the top dead center and / or the bottom dead center in an intake stroke when the engine speed is equal to or higher than a predetermined reference speed corresponding to a high speed. Means.

A sixth aspect of the invention is a variable valve mechanism that can change the closing timing of each intake valve;
Intake valve closing delay means for delaying the closing timing of each intake valve from the bottom dead center by the variable valve mechanism;
Injection timing control means for setting the fuel injection period of each fuel injection valve in the first half of the intake stroke;
Is provided.

  7th invention is provided with the division | segmentation injection means which injects a fuel by dividing into the first half and the latter half of an intake stroke by each said fuel injection valve.

  8th invention is provided with the injection differential means which shifts the fuel injection period of each said fuel injection valve, and hold | maintains it in a non-overlapping state.

A ninth aspect of the invention is an intake adjustment valve capable of changing a flow passage area of one intake port among the intake ports,
Injection state control means for injecting fuel with the two fuel injection valves in a state where the air flow rate of the one intake port is reduced by the intake adjustment valve.

According to the tenth invention, in the other fuel injection valve among the fuel injection valves, the outer region injection amount is set to be larger than the central region injection amount,
When the engine load is smaller than a predetermined reference load corresponding to a high load, in the intake stroke, fuel is injected only from the other fuel injection valve, and the intake port in which the one fuel injection valve is disposed There is provided a medium / low load control means for keeping the intake valve closed.

  According to the first invention, the fuel injected into the central region passes between the stems of the intake valves and flows into the central part of the cylinder. Further, the fuel injected into the outer region passes through the outside of each stem and flows into the cylinder outer periphery. Therefore, by increasing the center region injection amount, the injected fuel flowing into the cylinder outer periphery can be reduced, and the amount of fuel adhering to the cylinder inner wall surface can be suppressed. As a result, the amount of fuel vaporized in the air in the cylinder, rather than in the cylinder inner wall surface, can increase the cooling efficiency of the intake air by the vaporization of the fuel, and improve the fuel consumption and output. Further, it is possible to reduce torque fluctuation caused by fuel adhesion to the cylinder inner wall surface and improve exhaust emission.

  In addition, when viewed from the fuel injection valve side, the space volume (air amount) in the center of the cylinder corresponding to the center region is larger than the space volume of the cylinder outer periphery corresponding to the outer region. Therefore, by increasing the center region injection amount, the injected fuel can be appropriately distributed to the in-cylinder center portion and the in-cylinder outer periphery according to the air amount of each part in the cylinder. Thereby, in the whole cylinder, an air fuel ratio can be equalized and combustion can be homogenized. On the other hand, since the fuel is injected at the center position of the intake port including the straight port, the influence of the air flow on the fuel spray can be suppressed. As a result, fuel can flow into the cylinder in a stable spray shape, and variations in combustion between cycles can be reduced.

  According to the second invention, in the state where the intake valve is opened, the fuel injected from the fuel injection valve is an annular gap formed between the opening of the intake port and the umbrella of the valve, It flows into the cylinder through a C-shaped gap excluding the portion blocked by the stem. Therefore, it is possible to prevent the injected fuel from adhering to the stem and stabilize the amount of fuel flowing into the cylinder. In addition, by making the cross-sectional shape of the spray arc, the spray area can be maximized with respect to the annular gap generated during the opening of the intake valve. Thereby, atomization of the injected fuel can be promoted, and unburned HC and particulate matter (PM) in the exhaust gas can be reduced.

  According to the third aspect of the invention, when the intake air amount is large, the air flow that draws the injected fuel into the central portion of the cylinder becomes strong, and the fuel drawn into the central portion of the cylinder is in the cylinder on the opposite side of the intake port. It becomes easy to adhere to the wall surface. On the other hand, as the intake air amount increases, the air amount correspondence control unit can increase the ratio of the outer region injection amount to the central region injection amount and relatively decrease the central region injection amount. As a result, the amount of fuel adhering to the cylinder inner wall surface can be suppressed, for example, during high load operation where the intake air amount increases. Therefore, torque fluctuation can be reduced and exhaust emission can be improved.

  According to the fourth aspect of the invention, the engine speed corresponding control means can increase the ratio of the outer region injection amount to the central region injection amount and relatively decrease the center region injection amount as the engine speed is higher. . As a result, the amount of fuel adhering to the inner wall surface of the cylinder can be suppressed during high-speed operation, and the same effect as the third aspect of the invention can be obtained.

  According to the fifth aspect of the invention, during high speed operation, the air flow that draws injected fuel into the center of the cylinder becomes stronger, but in the vicinity of the top dead center and the bottom dead center that are far away from the middle position of the intake stroke, The air flow is relatively weak compared to the position. Therefore, according to the injection timing control means, the fuel can be injected at a timing when the air flow is relatively weak at the time of high rotation operation where the flow of intake air becomes strong, and the amount of fuel adhering to the inner wall surface of the cylinder is suppressed. be able to.

  According to the sixth aspect of the invention, by delaying the closing timing of the intake valve, the intake air amount can be reduced and a so-called Atkinson cycle can be realized. Thereby, thermal efficiency can be improved and fuel consumption can be improved. On the other hand, by setting the fuel injection period to the first half of the intake stroke, the injected fuel can be collected on the lower side (piston side) in the cylinder, and the fuel injection period can be kept away from the intake bottom dead center in time. Can do. Thereby, it is possible to prevent the injected fuel from blowing back to the intake port immediately before the intake valve is closed. Therefore, variation in the amount of air-fuel mixture in the cylinder can be suppressed and torque fluctuation can be reduced.

  According to the seventh aspect, fuel can be injected little by little in the first half and second half of the intake stroke, the degree of mixing of the injected fuel and air can be increased, and vaporization of the injected fuel can be promoted. For this reason, even when a straight port having a relatively weak function of stirring the air in the cylinder is used as the intake port, the homogeneity of the air-fuel mixture can be improved.

  According to the eighth aspect, it is possible to prevent the spray of fuel injected from the two fuel injection valves from colliding in the cylinder. Accordingly, it is possible to avoid the fuel atomization from being hindered by the collision of the fuel spray or to prevent the mixture from being biased, and the mixture can be stably formed.

  According to the ninth aspect of the invention, the injection state control means can reduce the air flow rate of one intake port by the intake adjustment valve and generate a swirl flow in the cylinder. And it is possible to inject fuel from the two fuel injection valves to different parts of the swirl flow. Thereby, the homogeneity of the air-fuel mixture can be improved, and the air flow in the cylinder can be strengthened to improve the combustion speed. Therefore, for example, the operating range in which lean combustion is possible can be expanded, and fuel consumption can be further improved.

  According to the tenth aspect of the invention, a relatively large amount of fuel can be injected into the outer region by the other fuel injection valve during medium and low load operation. Since the outer region corresponds to the outer periphery in the cylinder, a swirl flow can be generated in the cylinder by the momentum of the fuel injected into this region, and the swirl flow enhances the air flow in the cylinder and improves the combustion state. be able to. Therefore, by making the intake port a straight port, it is possible to obtain the effect of swirl flow using fuel injection during medium and low load operation while ensuring the maximum amount of intake air during high load operation.

It is a whole block diagram for demonstrating the system configuration | structure of Embodiment 1 of this invention. It is a block diagram which expands and shows the structure of 1 cylinder of an engine. It is explanatory drawing which shows the division | segmentation injection of the fuel in Embodiment 2 of this invention. In Embodiment 3 of this invention, it is explanatory drawing which shows the valve closing time of an intake valve, and the injection timing of a fuel. In Embodiment 4 of this invention, it is explanatory drawing which shows the injection timing of a fuel. In Embodiment 5 of this invention, it is a block diagram which expands and shows the structure of 1 cylinder of an engine. In Embodiment 6 of this invention, it is a block diagram which expands and shows the structure of 1 cylinder of an engine. FIG. 20 is an explanatory diagram showing control according to the sixth embodiment. In Embodiment 7 of this invention, it is explanatory drawing which shows the injection timing of a fuel. In Embodiment 8 of this invention, it is a block diagram which expands and shows the structure of 1 cylinder of an engine. It is a characteristic diagram for setting an outside injection ratio based on the amount of intake air. In Embodiment 9 of this invention, it is a characteristic diagram for setting an outside injection ratio based on an engine speed.

Embodiment 1 FIG.
[Configuration of Embodiment 1]
Hereinafter, the first embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is an overall configuration diagram for explaining a system configuration according to the first embodiment of the present invention. The system according to the present embodiment includes an engine 10 as an internal combustion engine. Although FIG. 1 illustrates a four-cylinder engine, the present invention is applied to an internal combustion engine having an arbitrary number of cylinders. A combustion chamber 12 is formed in each cylinder of the engine 10 by a piston (not shown), and the piston is connected to a crankshaft that is an output shaft of the engine 10. The engine 10 also includes an intake passage 14 that sucks intake air into each cylinder and an exhaust passage 16 through which exhaust gas is discharged from each cylinder. The intake passage 14 is provided with an electronically controlled throttle valve 18 that adjusts the amount of intake air.

  Each cylinder includes first and second intake ports 20A and 20B and first and second exhaust ports 22A and 22B, respectively. The intake ports 20A and 20B are formed as two parallel passages, and the upstream side is connected to the intake passage 14, and the downstream sides open to the combustion chamber 12 at different positions. Further, the exhaust ports 22 </ b> A and 22 </ b> B are open to the combustion chamber 12 on the upstream side and connected to the exhaust passage 16 on the downstream side.

  Here, the shape and arrangement of the intake ports 20A and 20B will be described with reference to FIG. FIG. 2 is a configuration diagram showing an enlarged configuration of one cylinder of the engine. As shown in this figure, the intake ports 20A and 20B are formed as straight ports extending linearly and have center axes L1 and L2, respectively. The intake ports 20A and 20B pass through one side and the other side with respect to the center O of the combustion chamber 12 in which the central axis lines L1 and L2 form a circular shape when the cylinder is viewed from the axial direction (plan view). Are arranged as follows. That is, the intake port 20A opens to the combustion chamber 12 on one side of the center O, and the intake port 20B opens to the combustion chamber 12 on the other side of the center O.

  Each cylinder includes first and second fuel injection valves 24A and 24B disposed in the intake ports 20A and 20B, and an ignition plug 26 that ignites an air-fuel mixture in the combustion chamber 12 (in-cylinder). Yes. Here, the fuel injection valve 24A is configured such that at least the fuel injection hole is disposed on the central axis L1 of the intake port 20A, and the fuel is injected toward the opening of the intake port 20A on the central axis L1. . Similarly, the fuel injection valve 24B has a fuel injection hole disposed on the central axis L2 of the intake port 20B, and is configured to inject fuel toward the opening of the intake port 20B on the central axis L2. . For this reason, in a state where the intake valves 28A and 28B are opened, the fuel injected from the fuel injection valves 24A and 24B directly reaches the cylinder. On the other hand, the spark plug 26 is disposed at the center O of the combustion chamber 12 in a plan view.

  In addition, the intake ports 20A and 20B are provided with first and second intake valves 28A and 28B each formed of a known poppet valve or the like. The intake valve 28A includes a substantially disc-shaped umbrella 30A that opens and closes the opening of the intake port 20A, and a rod-shaped stem 32A that supports the umbrella 30A at the center position. Similarly, the intake valve 28B includes an umbrella portion 30B and a stem 32B. On the other hand, the exhaust ports 22A and 22B are provided with exhaust valves 34A and 34B as shown in FIG.

  The engine 10 includes a variable valve mechanism 36 attached to the intake valves 28A and 28B. The variable valve mechanism 36 is configured by a known mechanism that can change at least the closing timing of the intake valves 28A and 28B for each valve. Examples of such a mechanism include a swing arm type variable valve mechanism as described in Japanese Patent Application Laid-Open No. 2007-132326, and a VVT (as described in Japanese Patent Application Laid-Open No. 2000-87769). Variable valve timing system), for example, an electromagnetically driven valve mechanism as described in Japanese Patent Application Laid-Open No. 2007-16710. These mechanisms can advance (fasten) and retard (slow) the closing timing of the intake valves 28A and 28B in accordance with a control signal input from the ECU 40 described later.

  The system according to the present embodiment includes a sensor system 38 including various sensors necessary for controlling the engine 10 and a vehicle on which the engine 10 is mounted, and an ECU (Electronic Control Unit) 40 that controls the operating state of the engine 10. I have. The sensor system 38 includes a crank angle sensor that detects a crank angle and an engine speed (engine speed), an air flow sensor that detects an intake air amount, a water temperature sensor that detects the temperature of engine cooling water, and an exhaust air-fuel ratio. An air-fuel ratio sensor, an accelerator opening sensor for detecting an accelerator operation amount (accelerator opening) of the vehicle, and the like are included. The sensor system 38 is connected to the input side of the ECU 40. On the other hand, on the output side of the ECU 40, various actuators including the throttle valve 18, fuel injection valves 24A and 24B, the spark plug 26, the variable valve mechanism 36, and the like are connected.

  The ECU 40 controls the operation by driving the actuators based on the engine operation information detected by the sensor system 38. Specifically, the engine speed and the crank angle are detected based on the output of the crank angle sensor, and the intake air amount is detected by the air flow sensor. The engine load is calculated based on the engine speed and the intake air amount, the fuel injection amount is calculated based on the intake air amount, the engine load, etc., and the fuel injection timing and the ignition timing are determined based on the crank angle. . Then, the fuel injection valves 24A and 24B are driven when the fuel injection timing comes, and the spark plug 26 is driven when the ignition timing comes. Further, the ECU 40 drives the variable valve mechanism 36 based on the crank angle to open and close the intake valves 28A and 28B at appropriate timing. Thereby, the air-fuel mixture is combusted in the combustion chamber 12 of each cylinder, and the engine 10 can be operated.

[Features of Embodiment 1]
In the present embodiment, the intake ports 20A and 20B are formed as straight ports, and the fuel injection positions of the fuel injection valves 24A and 24B are arranged on the central axes L1 and L2 of the intake ports 20A and 20B. The two fuel injection valves 24A, 24B supply fuel toward the openings of the intake ports 20A, 20B on the central axes L1, L2 during the intake stroke, that is, during the opening period of the intake valves 28A, 28B. It is set as the structure which injects. According to this configuration, since the fuel is injected at the center position of the straight port, the influence of the air flow on the fuel spray can be suppressed. As a result, fuel can flow into the cylinder in a stable spray shape, and variations in combustion between cycles can be reduced.

  In addition, an injection hole plate for realizing an asymmetric spray shape with respect to the central axis lines L1 and L2 is provided at the front ends of the fuel injection valves 24A and 24B. This nozzle hole plate has a plurality of fuel injection holes arranged in an arcuate shape (C shape) as described in, for example, Japanese Patent Application Laid-Open No. 2007-26295, and is centered on the center axes L1 and L2. It has an asymmetric shape. Accordingly, as shown in FIG. 2, the fuel injection valves 24A and 24B are configured such that the spray cross-sectional shapes F1 and F2 obtained by breaking the fuel spray along a plane perpendicular to the injection direction are C-shaped. . In the present embodiment, one notch Fc provided in the spray cross-sectional shapes F1, F2 is configured to match the positions of the stems 32A, 32B of the intake valves 28A, 28B.

  According to this configuration, in a state where the intake valves 28A and 28B are opened, the fuel injected from the fuel injection valves 24A and 24B is between the openings of the intake ports 20A and 20B and the umbrella portions 30A and 30B of the valves. Of the annular gap formed in the cylinder, the gas flows into the cylinder through a C-shaped gap excluding a portion blocked by the stems 32A and 32B. Further, portions of the annular gap that are blocked by the stems 32A and 32B are aligned with the spray-shaped notches Fc, so that fuel is not injected into the positions of the stems 32A and 32B.

  Therefore, it is possible to prevent the injected fuel from adhering to the stems 32A and 32B, and to stabilize the amount of fuel flowing into the cylinder. In addition, by making the cross-sectional shape of the spray arc, the spray area can be maximized with respect to the annular gap generated during the opening of the intake valves 28A and 28B. Thereby, atomization of the injected fuel can be promoted, and particulate matter (PM) in the exhaust gas can be reduced.

  Further, as shown in FIG. 2, two regions that are divided by the stems 32A and 32B are formed on the opening side of the intake ports 20A and 20B as viewed from the fuel injection valves 24A and 24B. These regions are a central region A located between the stems 32A and 32B and an outer region B located outside (on both sides) of the stems 32A and 32B. Of the fuel injected from the fuel injection valves 24A and 24B, the fuel injected into the central region A passes between the stems 32A and 32B and flows into the in-cylinder center. The fuel injected into the outer region B passes outside the stems 32A and 32B and flows into the cylinder outer periphery.

  For this reason, in the present embodiment, the amount of fuel injected into the central region A (central region injection amount) is set to be larger than the amount of fuel injected into the outer region B (outer region injection amount). Yes. In this configuration, for example, in an injection hole plate in which a plurality of fuel injection holes are arranged in an arc shape, the number of fuel injection holes corresponding to the central region A, the hole diameter, and the like are increased as compared with the fuel injection holes corresponding to the outer region B. It is realized by letting.

  According to the above configuration, the amount of injected fuel that flows into the outer periphery of the cylinder can be reduced, and the amount of fuel attached to the inner wall surface of the cylinder can be suppressed. As a result, the amount of fuel vaporized in the air in the cylinder, rather than in the cylinder inner wall surface, can increase the cooling efficiency of the intake air by the vaporization of the fuel, and improve the fuel consumption and output. Further, when the injected fuel adheres to the inner wall surface of the cylinder, the adhering fuel is carried over to the next cycle, thereby causing torque fluctuations or increasing unburned fuel, which may deteriorate exhaust emission. According to the above configuration, it is possible to reduce the torque fluctuation caused by such a cause and improve the exhaust emission.

  Further, when viewed from the fuel injection valves 24A and 24B side, the space volume (air amount) in the center of the cylinder corresponding to the center region A is larger than the space volume of the outer periphery in the cylinder corresponding to the outer region B. Therefore, by making the center region injection amount larger than the outer region injection amount, the injected fuel can be appropriately distributed to the in-cylinder central portion and the in-cylinder outer periphery according to the air amount of each part in the cylinder. Thereby, in the whole cylinder, an air fuel ratio can be equalized and combustion can be homogenized.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIG. The present embodiment is characterized in that the fuel injection is performed in the first half and the second half of the intake stroke in substantially the same configuration and control as in the first embodiment. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[Features of Embodiment 2]
FIG. 3 is an explanatory diagram showing split fuel injection in Embodiment 2 of the present invention. As shown in this figure, in this embodiment, the fuel injection valves 24A and 24B inject one cycle of injected fuel into the first half and the second half of the intake stroke. Although FIG. 3 illustrates the case where the fuel injection is divided twice, the number of divided injections in the present invention is not limited to two. Further, “TDC” and “BDC” in FIG. 3 indicate an exhaust top dead center and an intake bottom dead center, respectively.

  According to the above control, fuel can be injected little by little in the first half and second half of the intake stroke, the degree of mixing of the injected fuel and air can be increased, and vaporization of the injected fuel can be promoted. For this reason, even when a straight port having a relatively weak function of stirring the air in the cylinder is used as the intake ports 20A and 20B, in addition to the effects of the first embodiment, the homogeneity of the air-fuel mixture can be improved. it can. In the second embodiment, FIG. 3 shows a specific example of the divided injection means in claim 7.

Embodiment 3 FIG.
Next, Embodiment 3 of the present invention will be described with reference to FIG. The present embodiment is characterized in that the closing timing of the intake valve is delayed from the bottom dead center in the configuration and control substantially the same as in the first embodiment. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[Features of Embodiment 3]
FIG. 4 is an explanatory diagram showing the valve closing timing of the intake valve and the fuel injection timing in Embodiment 3 of the present invention. As shown in FIG. 4, in the present embodiment, the closing timing of the intake valves 28A, 28B is delayed from the intake bottom dead center, and the fuel injection period of the fuel injection valves 24A, 24B is set to the first half of the intake stroke. It is configured to do.

  According to the above control, the intake air amount can be reduced by delaying the closing timing of the intake valves 28A and 28B, and a so-called Atkinson cycle can be realized. Thereby, in addition to the effect of Embodiment 1, it can improve a thermal efficiency and can improve a fuel consumption. On the other hand, by setting the fuel injection period to the first half of the intake stroke, the injected fuel can be collected on the lower side (piston side) in the cylinder, and the fuel injection period can be kept away from the intake bottom dead center in time. Can do. Thereby, it is possible to prevent the injected fuel from blowing back to the intake ports 20A and 20B immediately before the intake valves 28A and 28B are closed. Therefore, variation in the amount of air-fuel mixture in the cylinder can be suppressed and torque fluctuation can be reduced. In the third embodiment, FIG. 4 shows a specific example of the intake valve closing delay means and the injection timing control means in claim 6.

Embodiment 4 FIG.
Next, a fourth embodiment of the present invention will be described with reference to FIG. The present embodiment is characterized in that the fuel injection periods of the two fuel injection valves are shifted in substantially the same configuration and control as in the first embodiment. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[Features of Embodiment 4]
FIG. 5 is an explanatory diagram showing the fuel injection timing in the fourth embodiment of the present invention. As shown in this figure, in the present embodiment, the fuel injection periods are shifted from each other so that the fuel injection periods of the fuel injection valves 24A and 24B do not overlap. According to this configuration, it is possible to prevent the spray of fuel injected from the fuel injection valves 24A and 24B from colliding in the cylinder. Accordingly, it is possible to prevent the atomization of the fuel from being obstructed by the collision of the fuel spray and the occurrence of the bias of the air-fuel mixture, and in addition to the effects of the first embodiment, the air-fuel mixture is stably formed. be able to. In the fourth embodiment, FIG. 5 shows a specific example of the injection differential means in claim 8.

Embodiment 5 FIG.
Next, a fifth embodiment of the present invention will be described with reference to FIG. In this embodiment, in addition to substantially the same configuration and control as in the first embodiment, fuel injection is performed by two fuel injection valves in a state where the air flow rate of one intake port is decreased by the intake adjustment valve. It is characterized by that. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[Features of Embodiment 5]
FIG. 6 is an enlarged configuration diagram showing the configuration of one cylinder of the engine in the fifth embodiment of the present invention. As shown in this figure, in the present embodiment, a swirl control valve (SCV) 50 constituting an intake adjustment valve is provided in the first intake port 20A. The SCV 50 is configured by, for example, an electronically controlled butterfly valve or the like, and is disposed on the upstream side of the fuel injection valve 24A. The SCV 50 is controlled by the ECU 40 to change the flow passage area of the intake port 20A, and is configured to block the air flow in the intake port 20A in the fully closed position. In the present embodiment, in the intake stroke, the fuel is simultaneously injected by the fuel injection valves 24A and 24B in a state where the SCV 50 is driven to the closed side to reduce the air flow in the intake port 20A.

  According to the above configuration, a swirl flow can be generated in the cylinder by the SCV 50, and fuel can be injected from the two fuel injection valves 24A and 24B to different portions of the swirl flow. Thereby, the homogeneity of the air-fuel mixture can be improved, and the air flow in the cylinder can be strengthened to improve the combustion speed. Therefore, in addition to the operational effects of the first embodiment, for example, the operating range in which lean combustion is possible can be expanded, and fuel consumption can be further improved. In the fifth embodiment, FIG. 6 shows a specific example of the injection state control means in claim 9.

Embodiment 6 FIG.
Next, a sixth embodiment of the present invention will be described with reference to FIGS. The present embodiment is characterized in that the spray shapes of the two fuel injection valves are made different in the configuration and control substantially the same as in the first embodiment. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[Features of Embodiment 6]
FIG. 7 is an enlarged configuration diagram showing the configuration of one cylinder of the engine in the sixth embodiment of the present invention. In the present embodiment, the spray shapes of the fuel injection valves 24A and 24B ′ have a C-shaped cross-sectional shape, as in the first embodiment. Further, the first fuel injection valve 24A is configured such that the central region injection amount is larger than the outer region injection amount. However, contrary to the first embodiment, the second fuel injection valve 24B ′ is configured such that the outer region injection amount is larger than the central region injection amount. This configuration is realized, for example, by increasing the number of fuel injection holes corresponding to the outer region B, the hole diameter, and the like in the injection hole plate of the fuel injection valve 24B ′ as compared with the fuel injection hole corresponding to the central region A. .

  FIG. 8 is an explanatory diagram showing the control according to the sixth embodiment. As shown in FIG. 8 (a), when the low load operation or the intermediate load operation is performed (hereinafter referred to as a medium / low load operation), the first fuel injection valve 24A is stopped in the intake stroke. In this state, fuel is injected by the second fuel injection valve 24B ′. At this time, the first intake valve 28A is kept closed, and only the second intake valve 28B is opened. Whether or not the vehicle is operating at a medium or low load is determined based on whether or not the engine load is smaller than a predetermined reference load corresponding to the high load. When the engine load is smaller than the reference load, the ECU 40 determines that the middle / low load operation is being performed, and executes the above control. On the other hand, when the engine load is equal to or higher than the reference load, it is determined that the engine is operating at a high load, and the same control as in the first embodiment is executed as shown in FIG. That is, fuel injection is performed by both the fuel injection valves 24A and 24B with the intake valves 28A and 28B opened.

  According to the above configuration, a relatively large amount of fuel can be injected into the outer region B by the fuel injection valve 24B ′ during the medium and low load operation. Since the outer region B corresponds to the outer periphery in the cylinder, a swirl flow can be generated in the cylinder by the momentum of the fuel injected into this region, and the combustion state is improved by strengthening the air flow in the cylinder by the swirl flow. can do. Therefore, by making the intake ports 20A and 20B straight ports, the intake air amount at the time of high load operation is ensured to the maximum, and at the time of medium to low load operation, the effect of swirl flow is obtained by using fuel injection. Can do. In the sixth embodiment, FIG. 8 shows a specific example of the medium and low load control means in claim 10.

Embodiment 7 FIG.
Next, a seventh embodiment of the present invention will be described with reference to FIG. The present embodiment is characterized in that fuel injection at high rotation is performed in the vicinity of the top dead center and / or the bottom dead center in the same configuration and control as in the first embodiment. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[Features of Embodiment 7]
The intake air flowing into the cylinder tends to gather at the center of the cylinder by forming a stronger flow as the engine speed is higher (as the intake air amount is larger). As a result, the injected fuel is drawn into the center of the cylinder by the strong air flow, and with the momentum, the portion of the cylinder inner wall located in front of the intake ports 20A and 20B, that is, the wall on the exhaust ports 22A and 22B side. It becomes easy to adhere. Therefore, the injected fuel that adheres to the vicinity of the exhaust ports 22A and 22B through the in-cylinder central portion tends to increase as the intake air amount increases.

  For this reason, in the present embodiment, when the engine speed is equal to or higher than a predetermined reference speed (during high speed operation), as shown in FIG. The fuel injection is performed near the dead point. On the other hand, when the engine rotational speed is less than the reference rotational speed (during low-medium speed operation), the same control as in the first embodiment is executed as shown in FIG. 9B. Note that. FIG. 9 is an explanatory diagram showing the fuel injection timing in the seventh embodiment of the present invention. In the intake stroke, the flow of air sucked into the cylinder by the downward movement of the piston is fastest at a crank angle (intermediate position of the intake stroke) near ATDC 90 °. This crank angle corresponds to the timing when the descending speed of the piston becomes the fastest.

  On the other hand, in the vicinity of the top dead center and the bottom dead center far away from the intermediate position of the intake stroke, the air flow is relatively weak compared to the intermediate position. Therefore, according to the present embodiment, the fuel can be injected at a timing when the air flow is relatively weak, such as during high-speed operation where the flow of intake air becomes strong, and the amount of fuel adhering to the inner wall surface of the cylinder is suppressed. can do. Therefore, as in the first embodiment, torque fluctuation can be reduced and exhaust emission can be improved.

  Note that the reference rotational speed is set in correspondence with a high rotational speed such that the flow of the intake air easily collects in the center of the cylinder and is stored in the ECU 40 in advance. Further, in the present embodiment, the fuel injection may be performed only in the vicinity of one of the top dead center and the bottom dead center, or the structure implemented in both the vicinity of the top dead center and the vicinity of the bottom dead center. It is good. Moreover, in the said Embodiment 7, FIG. 9 has shown the specific example of the injection state control means in Claim 5. FIG.

Embodiment 8 FIG.
Next, an eighth embodiment of the present invention will be described with reference to FIGS. The present embodiment is characterized in that, in addition to substantially the same configuration and control as in the first embodiment, the ratio between the central region injection amount and the outer region injection amount is changed according to the intake air amount. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[Features of Embodiment 8]
FIG. 10 is an enlarged configuration diagram showing the configuration of one cylinder of the engine in the eighth embodiment of the present invention. As shown in this figure, in the present embodiment, variable injection hole type fuel injection valves 60A and 60B are employed, and these fuel injection valves 60A and 60B are disclosed in, for example, Japanese Patent Application Laid-Open No. 2007-297987. It has a known configuration as described in Kaihei 04-76266. More specifically, the fuel injection valves 60A and 60B include a variable mechanism that opens and closes some of the plurality of fuel injection holes formed in the injection hole plate, for example. Thereby, fuel injection valve 60A, 60B can change the ratio of a center area | region injection quantity and an outer area | region injection quantity according to the control signal input from ECU40.

  And in this Embodiment, as shown in FIG. 11, it is set as the structure which increases the ratio (henceforth an outer injection ratio) of the outer area | region injection quantity with respect to a center area | region injection quantity, so that there are many intake air quantities. FIG. 11 is a characteristic diagram for setting the outside injection ratio based on the intake air amount. This characteristic data is stored in advance in the ECU 40 as map data, for example. The ECU 40 calculates the outside injection ratio with reference to the map data of FIG. 11 based on the intake air amount detected by the airflow sensor or the like. Then, the central region injection amount and the outer region injection amount are determined based on the calculated value of the outer injection ratio, and the variable mechanisms of the fuel injection valves 60A and 60B are driven so that these injection amounts are realized.

  As described above, when the intake air amount is large, the air flow for drawing the injected fuel into the center of the cylinder becomes strong, and the amount of fuel adhering to the cylinder inner wall surface tends to increase. On the other hand, in the present embodiment, when the entire fuel injection amount (central region injection amount + outer region injection amount) is constant, the outer region injection amount is increased as the intake air amount increases, and the central region is increased. The injection amount can be reduced. This reduces the amount of fuel injected from the central region A of the intake ports 20A, 20B to the center of the cylinder during high load operation where the intake air amount increases, thereby suppressing the amount of fuel adhering to the cylinder inner wall surface. be able to. Therefore, as in the first embodiment, torque fluctuation can be reduced and exhaust emission can be improved. In the eighth embodiment, FIG. 11 shows a specific example of the air amount correspondence control means in claim 3.

Embodiment 9 FIG.
Next, Embodiment 9 of the present invention will be described with reference to FIG. The present embodiment is characterized in that, in the same configuration as in the eighth embodiment, the ratio of the central region injection amount and the outer region injection amount is changed according to the engine speed. In the present embodiment, the same components as those in the eighth embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[Features of Embodiment 9]
As described above, when the engine speed is high, the air flow that draws the injected fuel into the center of the cylinder becomes strong, and the amount of fuel adhering to the inner wall surface of the cylinder tends to increase. For this reason, in this Embodiment, as shown in FIG. 12, it is set as the structure which increases an outside injection ratio, so that an engine speed is high. FIG. 12 is a characteristic diagram for setting the outside injection ratio based on the engine speed, and this characteristic data is stored in advance in the ECU 40 as map data, for example. The ECU 40 refers to the map data in FIG. 12 and calculates the outside injection ratio based on the engine speed. Then, as described in the eighth embodiment, the variable mechanisms of the fuel injection valves 60A and 60B are driven so that the calculated value of the outer injection ratio is realized.

  According to the above configuration, the amount of fuel adhering to the cylinder inner wall surface is reduced by reducing the amount of injected fuel flowing from the central area A of the intake ports 20A, 20B into the center of the cylinder during high-speed operation where the intake air quantity increases. Can be suppressed. Thereby, substantially the same effect as that of the eighth embodiment can be obtained. In the ninth embodiment, FIG. 12 shows a specific example of the rotation speed correspondence control means in claim 4.

  In Embodiments 1 to 9 described above, the configurations included in the present invention are individually illustrated. However, the present invention is not limited to the individual configurations described in the embodiments. That is, in the present invention, among the configurations shown in Embodiments 1 to 9, any plurality of configurations may be combined within a realizable range.

10 Engine (Internal combustion engine)
12 Combustion chamber 14 Intake passage 16 Exhaust passage 18 Throttle valves 20A, 20B First and second intake ports 22A, 22B First, second exhaust ports 24A, 60A First fuel injection valves 24B, 24B ', 60B First Two fuel injection valves 26 Spark plugs 28A and 28B First and second intake valves 30A and 30B Umbrella portions 32A and 32B Stems 34A and 34B First and second exhaust valves 36 Variable valve mechanism 38 Sensor system 40 ECU
50 Swirl control valve (intake adjustment valve)
A Central area B Outer area L1, L2 Center axis

Claims (10)

Two intake ports that are each formed as a straight port that extends in a straight line and opens into the combustion chamber, and whose center axis passes through one side and the other side with respect to the center of the combustion chamber;
Two intake valves respectively provided on the two intake ports, each having an umbrella portion that opens and closes an opening portion of the intake port and a stem that supports the umbrella portion at a central position;
Two fuel injection valves that are respectively provided in the two intake ports and inject fuel toward the opening of the intake port on the central axis of each intake port;
Each fuel injection valve is configured to inject fuel into a central region located between the stems of the two intake valves and an outer region located outside the stems, respectively.
In at least one of the fuel injection valves, the central region injection amount that is the amount of fuel injected into the central region is set to be larger than the outer region injection amount that is the amount of fuel injected into the outer region. A control device for an internal combustion engine.   Each of the fuel injection valves is configured such that the fuel spray is broken in a plane perpendicular to the injection direction so that the cross-sectional shape of the spray is C-shaped, and one notch provided in the cross-sectional shape of the spray is formed. The control apparatus for an internal combustion engine according to claim 1, wherein the control apparatus is configured to match the position of the stem. Each of the fuel injection valves is constituted by an injection hole variable type injection valve capable of changing a ratio between the central region injection amount and the outer region injection amount.
3. The control apparatus for an internal combustion engine according to claim 1, further comprising an air amount corresponding control unit that increases a ratio of the outer region injection amount to the central region injection amount as the intake air amount increases. Each of the fuel injection valves is constituted by an injection hole variable type injection valve capable of changing a ratio between the central region injection amount and the outer region injection amount.
The control device for an internal combustion engine according to claim 1 or 2, further comprising a rotation speed correspondence control means for increasing a ratio of the outer region injection amount to the central region injection amount as the engine speed is higher.   An injection timing control means for performing fuel injection near the top dead center and / or the bottom dead center in the intake stroke when the engine speed is equal to or higher than a predetermined reference speed corresponding to a high speed. Item 5. The control device for an internal combustion engine according to any one of Items 1 to 4. A variable valve mechanism capable of changing the closing timing of each intake valve;
Intake valve closing delay means for delaying the closing timing of each intake valve from the bottom dead center by the variable valve mechanism;
Injection timing control means for setting the fuel injection period of each fuel injection valve in the first half of the intake stroke;
The control apparatus for an internal combustion engine according to any one of claims 1 to 5, further comprising:   The control device for an internal combustion engine according to any one of claims 1 to 4, further comprising split injection means for injecting fuel into the first half and the second half of an intake stroke by each fuel injection valve.   The control apparatus for an internal combustion engine according to any one of claims 1 to 7, further comprising injection differential means that shifts a fuel injection period of each fuel injection valve and holds the fuel injection periods in a non-overlapping state. An intake adjustment valve capable of changing the flow passage area of one of the intake ports;
Injection state control means for injecting fuel with the two fuel injection valves in a state where the air flow rate of the one intake port is reduced by the intake adjustment valve;
The control apparatus for an internal combustion engine according to any one of claims 1 to 8, further comprising: In the other fuel injection valve among the fuel injection valves, the outer region injection amount is set to be larger than the central region injection amount.
When the engine load is smaller than a predetermined reference load corresponding to a high load, in the intake stroke, fuel is injected only from the other fuel injection valve, and the intake port in which the one fuel injection valve is disposed The control device for an internal combustion engine according to any one of claims 1 to 9, further comprising medium-to-low load control means for holding the intake valve in a closed state.

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