JP5673397B2 - Engine control device - Google Patents

Description

  The present invention relates to an engine control device that controls valve opening / closing timing and fuel injection timing of a port injection type four-cycle engine to reduce blow-through HC.

  As a drive source mounted on an automobile (hereinafter also referred to as a vehicle), a four-cycle engine (internal combustion engine) is generally used. This engine has one or a plurality of cylinders, and each cylinder has a plurality of intake ports for introducing fresh air (air before combustion) into the cylinders and an exhaust port for discharging exhaust gas after combustion from within the cylinders. And are connected. Then, intake is performed by opening the intake valve provided in the intake port, and exhaust is performed by opening the exhaust valve provided in the exhaust port.

In recent years, an engine having a variable valve timing mechanism capable of changing the opening and closing timings of an intake valve and an exhaust valve has been put into practical use in order to improve fuel consumption and reduce exhaust emission caused by HC (unburned fuel).
This variable valve timing mechanism is realized by a mechanism that changes the relative rotational phase of the camshaft with respect to the crankshaft, for example. Thereby, the phase of the camshaft corresponding to the opening start timing and the opening end timing of the valve is controlled in the advance angle direction or the retard angle direction. One of the control of the opening / closing timing of the intake / exhaust valve is so-called valve overlap control in which the period during which the intake valve is opened and the period during which the exhaust valve is opened overlap. According to this valve overlap control, it is possible to improve the charging efficiency by using the inertia effect of intake and exhaust in the middle and high load regions of the engine.

  However, in a general port-injection engine, the intake air flow rate increases during the overlap opening and closing periods of the intake and exhaust valves (hereinafter also referred to as valve overlap periods), and the fuel sucked into the cylinder from the intake port remains in the cylinder. HC that is blown out and discharged to the exhaust port as it is (blow-through HC) is generated, which is a problem in terms of fuel consumption and exhaust gas performance. In particular, in the case of an engine with a supercharger, a large amount of HC (fuel) blown out from the intake port to the exhaust port is generated when fuel injection is performed during the valve overlap period during supercharging operation. It has become a challenge.

  As a countermeasure, direct injection of the fuel injection system can be mentioned. In other words, according to the direct injection engine that directly injects fuel into the cylinder, fuel injection can be performed separately from the introduction of fresh air into the cylinder. By performing control to inject fuel, it is possible to suppress HC blow-through from the intake port to the exhaust port during the valve overlap period.

However, the direct injection type engine has an expensive fuel injection system and causes an increase in cost. Therefore, there is a demand for the development of a technology that can reduce the blow-through HC during the valve overlap period while using the port injection type that is advantageous in terms of cost. ing.
Patent Document 1 discloses a technology for reducing blow-through HC by changing the fuel injection direction of a fuel injection valve in an engine having a variable valve timing mechanism that is a general port injection type. In this technique, if fuel injection is performed in the intake stroke after the end of the valve overlap period, the required amount of fuel cannot be injected until the intake valve is completely closed. Fuel is injected toward the inner wall surface of the intake port upstream from the vicinity of the mouth. Thus, immediately after the intake valve is opened, the injected fuel does not stay in the vicinity of the intake port, and the blow-through HC can be reduced.

  By the way, an engine (hereinafter also referred to as a multi-port injection engine) having a fuel injection valve in each intake port connected to each cylinder has been developed (see Patent Documents 2 and 3). This multi-port injection type engine can suppress an increase in the cost of the fuel injection system as compared with the direct injection type engine, and can perform fine fuel injection control corresponding to the operation of each intake valve.

  In this multi-port injection engine, from the viewpoint of securing a combustible air mixture acceleration period, fuel injection is usually performed in the exhaust stroke as in a general port injection engine, but fuel is injected in the intake stroke. Technology is also being developed. For example, in Patent Document 3, in a multi-port injection type engine having a variable valve timing mechanism, fuel is injected (intake-synchronized injection) while the intake valve is open (intake stroke). It is disclosed that an intake air cooling action is obtained by utilizing the latent heat of fuel vaporization to improve the charging efficiency and decrease the knocking property.

JP 2005-105983 A JP 2007-292058 A Japanese Patent No. 4525441

  In the technique of Patent Document 1, although it is possible to suppress HC blow-through from the intake port to the exhaust port during the valve overlap period, fuel is injected toward the intake port inner wall surface upstream from the vicinity of the intake port. The injected fuel adheres to the wall surface of the port, the fuel cannot be atomized sufficiently, and the combustion may not be performed well. As a result, not only the engine output torque is not sufficiently generated, but also exhaust emission may be increased.

  In this regard, the multi-port injection engine has the characteristic that it can perform fine fuel injection control corresponding to the operation of each intake valve, so that it is possible to suppress blowout exhaust of HC during the valve overlap period. In addition, the cost increase of the fuel injection system can be suppressed as compared with the direct injection type engine. However, Patent Documents 2 and 3 do not have such attention.

  The present invention was devised in view of such problems. In a multi-port injection engine, when the valve overlap is used to improve the charging efficiency and secure the output torque, the blow-through HC is reduced. It is an object of the present invention to provide an engine control device that can improve fuel consumption and reduce exhaust emission.

In order to achieve the above object, an engine control apparatus of the present invention includes a first intake valve that opens and closes an intake port to a combustion chamber in a first intake port, and a connection to the combustion chamber in a second intake port. A second intake valve that opens and closes the intake port; an exhaust valve that opens and closes an exhaust port to the combustion chamber in the exhaust port; a first fuel injection means provided in the first intake port; and the second A second fuel injection means provided in the intake port of the engine, an operating state detecting means for detecting the operating state of the engine, and the opening / closing timing of each intake valve based on the detection information by the operating state detecting means individually Intake valve control means for controlling the fuel injection control means, and fuel injection control means for individually controlling the fuel injection timing by each of the fuel injection means based on detection information by the operating state detection means, A control apparatus for an engine having the is detected operating state by the operating state detecting means perform particular control and a specific operating region, said a particular control, the intake valve control means, said first A valve overlap that overlaps the opening period of the intake valve and the opening period of the exhaust valve only during the first period, and that overlaps the opening period of the second intake valve and the opening period of the exhaust valve. The overlap is not performed or is performed only for a second period shorter than the first period, and the fuel injection control means is configured such that the fuel injected by the first fuel injection means is the intake port of the first intake port. The timing of fuel injection by the first fuel injection means is set so that the exhaust valve is closed when reaching the exhaust port from the combustion chamber via Gosuru together, wherein the overlap period between the arrival time of the exhaust port of the first period and the injected fuel by the first fuel injection mechanism (first overlap period T ₁₎ is the said second period The fuel injection by the first fuel injection means is performed so as to be equal to or shorter than the overlap period (second overlap period T ₂ ) with the arrival period of the fuel injected by the second fuel injection means to the exhaust port. It is characterized by being carried out later than the fuel injection by the fuel injection means.

In the specific control, the fuel injection control means performs fuel injection by the first fuel injection means during an open period of the first intake valve, and performs fuel injection by the second fuel injection means. It is preferable to carry out during the closing period of the second intake valve.
The operating state detecting means includes engine speed detecting means for detecting the engine speed and intake pressure detecting means for detecting the intake pressure, and the specific operating region is the engine speed detecting means. The engine speed detected by the above is within a predetermined range (for example, the engine speed range in which the charging efficiency is remarkably improved by providing a valve overlap period) and detected by the intake pressure detecting means It is preferable that the intake pressure is in an operating region that is equal to or higher than the exhaust pressure that flows out of the exhaust port.

Further, the required output torque calculating means for calculating a required output torque of the driver, and an output torque detecting means for detecting an actual output torque of the engine, calculated by previous SL demanded output torque calculating means the required output torque In contrast, when the actual output torque of the engine detected by the output torque detecting means is in a shortage state, even if the operating state of the engine detected by the operating state detecting means is in the specific operating region Insufficient output response control is performed, and in the inadequate output response control, the intake valve control means performs control so as to increase the second period within the range of the first period, and the fuel injection control means includes: It is preferable that fuel injection by the second fuel injection means is performed during a valve opening period of the second intake valve. That is, when the actual output torque of the engine is insufficient, the valve overlap period of the first intake valve is controlled to the first period, and the valve overlap period of the second intake valve is within the range of the first period. The fuel injection by the first fuel injection means is performed during the opening period of the first intake valve, and the fuel injection by the second fuel injection means is controlled by the second intake air. It is preferably carried out during the opening period of the valve.

  For example, it further includes a throttle opening degree control for controlling the opening degree of the throttle valve based on the detection information by the operating state detecting means, and the output torque detecting means for the required output torque calculated by the required output torque calculating means. When the detected shortage of the actual output torque of the engine is significant (when the actual output torque is significantly insufficient with respect to the required output torque), the throttle opening control unit corrects and increases the throttle opening. It is preferable to do.

Further, a compressor is provided on the upstream side of the first and second intake ports, and the operating state detecting means is connected to the compressor and the exhaust pressure before passing through the turbine provided in the exhaust passage. The specific operation region has an engine speed detected by the engine speed detection means within a predetermined range, and is detected by the intake pressure detection means. It is preferable that the intake pressure is an operation region that is equal to or higher than the exhaust pressure detected by the exhaust pressure detecting means.

(1) According to the engine control apparatus of the present invention, the intake valve control means is configured so that the opening period of the first intake valve overlaps with the opening period of the exhaust valve by the first period. Can be used to promote filling efficiency and secure output torque.
Further, since the fuel injection by the second fuel injection means is performed earlier than the fuel injection by the first fuel injection means, it is possible to promote the vaporization of the injected fuel and the mixing with fresh air. .

Further, the intake valve control means injects the second intake valve into the second intake port so that the open period of the second intake valve does not overlap with the open period of the exhaust valve or overlaps only the second period shorter than the first period. It is possible to eliminate or suppress the blown-out fuel to the exhaust side due to the valve overlap, and to prevent or reduce the blow-through HC.
If the fuel injection timing is advanced, the fuel adhering to the wall of the port immediately after injection is also vaporized, which has the advantage of promoting mixing with air, but on the other hand, valve overlap (overlap of intake valve opening period and exhaust valve opening period) Thus, when a part of the air-fuel mixture passes through the combustion chamber and blows into the exhaust port, the fuel is sufficiently contained in the air-fuel mixture, and the amount of blow-through fuel increases.

  On the other hand, if the fuel injection timing is delayed, vaporization of the fuel adhering to the port wall surface immediately after injection is delayed, so mixing with the air is also delayed.On the other hand, at the time of valve overlap, the fuel adhering to the port wall surface is delayed. Since a part of the air-fuel mixture that does not contain a part of the fuel passes through the combustion chamber and blows into the exhaust port, the amount of blow-by fuel is suppressed and the blow-through HC can be reduced.

In addition, if the valve overlap is lengthened, the charging efficiency of the intake air is improved. On the other hand, the air-fuel mixture is blown out to the exhaust port due to the valve overlap.
Accordingly, since the fuel injection control means performs the fuel injection by the first fuel injection means later than the fuel injection by the second fuel injection means, the valve overlap is long for the intake air of the first intake port. (The first period is longer than the second period.) As a result, the amount of air blown through the exhaust port to the exhaust port is large, but the fuel in the mixture remains in the port as a droplet due to adhesion to the wall of the port and vaporizes. Since the amount of fuel that is delayed is small, the amount of blow-by fuel is suppressed. As for the intake air of the second intake port, a part of the air-fuel mixture containing a sufficient amount of fuel and having a relatively high fuel concentration passes through the combustion chamber and blows out into the exhaust port, but the valve overlap is short (the first 2 is shorter than the first period), the amount of air-fuel mixture blown into the exhaust port is small, and the amount of blow-through fuel is suppressed.

The fuel injection control means, when the first fuel injection means overlaps the first fuel injection means to reach the exhaust port of the injected fuel with the first period , the overlap period (first The overlapping period T ₁ ) is made shorter than the overlapping period (second overlapping period T ₂ ) in the case where the second fuel injection means reaches the exhaust port and the second period overlaps. For the purpose of control, even if the arrival period of the injected fuel to the exhaust port by the second fuel injection means overlaps with the second period shorter than the first period, the arrival period of the injected fuel to the exhaust port The overlapping period (second overlapping period T ₂ ) with the second period is also limited by the short valve overlap period. On the other hand, the first period is longer than the second period. However, when the first fuel injection means overlaps the arrival period of the injected fuel to the exhaust port and the first period, the injected fuel flows to the exhaust port. Overlapping period when the arrival period and the first period overlap (the first overlapping period T ₁ ) when the arrival period of the injected fuel to the exhaust port by the second fuel injection means and the second period overlap. Since it is shorter than the period (second overlap period T ₂ ), the overlap period (first overlap period T ₁ ) is also limited. Therefore, an increase in the blow-by fuel amount is suppressed, and the blow-through HC can be reduced.
As a result, the output torque of the engine can be secured, and the blow-through HC can be reduced to improve fuel consumption and reduce exhaust emission.

(2) Further, the fuel injection control means performs the fuel injection by the first fuel injection means in the opening period of the first intake valve, that is, in the intake stroke, not in the closing period of the first intake valve before the valve overlap. If implemented, it becomes possible to supply fuel into the combustion chamber after completion of the valve overlap, and blow-through HC can be reduced.

  Further, in the first intake port, if fuel is injected in the intake stroke, it is difficult to secure the mixing promotion time of the fuel and fresh air. However, the fuel injection control means performs the fuel injection by the second fuel injection means. If the second intake valve is closed, the fuel is injected in the second intake port before the intake stroke until the injected fuel enters the combustion chamber by opening the second intake valve. It is possible to ensure a long period of time for promoting the mixing of fuel and fresh air only for the period of time, and the mixture that has been promoted to enter the combustion chamber from the second intake port is transferred from the first intake port to the combustion chamber. Mixing of the fuel that enters the fuel and fresh air is also promoted, and combustion can be performed satisfactorily.

(3) When the intake pressure is larger than the exhaust pressure, HC blow-through is likely to occur, but when the intake pressure is smaller than the exhaust pressure, HC blow-through is difficult to occur. For this reason, if the case where the intake pressure at which HC blow-through is likely to occur is larger than the exhaust pressure flowing out from the exhaust port is set as the specific operation region, the fuel injection timing by the first fuel injection means is appropriately controlled, and the HC blow-through is controlled. Can be reduced.
Improvement of charging efficiency due to valve overlap depends on the engine speed. For example, if the specific operating range is within a predetermined range such as the range of engine speed at which charging efficiency can be reliably improved by valve overlap, the charging efficiency Can be effectively improved and blow-through HC can be reduced.

(4) If the intake valve control means performs control so as to increase the second period within the range of the first period, the valve overlap period of the second intake valve increases, that is, the valve overlap. When there is no valve overlap (the second period is zero), the valve overlap is provided, and when there is a valve overlap, the period (second period) is increased, so that the charging efficiency can be further improved. At this time, if the fuel injection by the first and second fuel injection means is performed during the opening period of the first and second intake valves, the fuel and fresh air may not be sufficiently mixed. The blow-through HC can be reduced and the engine output can be improved.

(5) Even in the case of having a valve overlap period, if the injected fuel cannot pass through the exhaust port, the HC will not blow through. For this reason, the fuel injection control means is configured such that the exhaust valve is closed when the fuel injection by the first fuel injection means reaches the exhaust port from the fuel chamber via the intake port of the first intake port. If the timing of fuel injection by the first fuel injection means is controlled, it is possible to prevent HC from being blown out.

(6) If a compressor is provided on the upstream side of the first and second intake ports and a turbine connected to the compressor is provided in the exhaust passage, intake air is forced by the compressor via the turbine using the exhaust flow. Therefore, the output torque can be ensured by further improving the charging efficiency of the intake air. At this time, in the specific operation region, if the engine speed is within a predetermined range and the intake pressure is an operation region in which the intake pressure is equal to or higher than the exhaust pressure, it is possible to perform fuel injection appropriate for fluctuations in the intake and exhaust pressures. it can.

It is a lineblock diagram of the engine control device concerning a 1st embodiment of the present invention. It is a typical top view of the cylinder upper part which shows the intake port and exhaust port of each cylinder of the engine concerning 1st Embodiment of this invention. It is a figure explaining the specific driving | operation area | region which applies control by the engine control apparatus concerning 1st Embodiment of this invention. FIG. 4 is a diagram for explaining valve opening / closing timings and fuel injection timings controlled by the engine control apparatus according to the first embodiment of the present invention. FIG. 4 (a) shows opening / closing timings of each intake valve and exhaust valve. (B) shows the fuel injection timing of each injector. It is a flowchart explaining the control flow by the engine control apparatus concerning 1st Embodiment of this invention. It is a flowchart explaining the flow of the output shortage response control by the engine control apparatus concerning 1st Embodiment of this invention. It is a figure explaining the opening-and-closing timing and fuel-injection timing of a valve controlled by the engine control device concerning other embodiments of the present invention, and Drawing 7 (a) shows each intake valve and exhaust valve concerning a 2nd embodiment. FIG. 7 (b) shows the fuel injection timing of each injector according to the second embodiment, and FIG. 7 (c) shows the fuel injection timing of each injector according to the third embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
1 to 6 illustrate an engine control apparatus according to a first embodiment of the present invention. FIG. 1 is a configuration diagram thereof, FIG. 2 is a schematic plan view of an upper part of a cylinder of the engine, and FIG. FIG. 4 is a diagram for explaining a specific operation region to which the control is applied, FIG. 4 is a diagram for explaining valve opening / closing timing and fuel injection timing by the control, FIG. 5 is a flowchart for explaining the control flow, and FIG. It is a flowchart explaining these.

[Main engine configuration]
First, an engine to which the engine control apparatus according to the present embodiment is applied and its peripheral configuration will be described. The engine according to the present embodiment is a four-cycle internal combustion engine and is mounted on an automobile.
The engine 10 according to the present embodiment is a multi-valve multi-cylinder engine. In FIG. 1, one of a plurality of cylinders (cylinders) 19 provided in the multi-cylinder engine 10 is shown in a longitudinal section.

As shown in FIG. 1, a plurality of cylinders 19 are formed in a cylinder block 10B of the engine 10 in a direction orthogonal to the drawing, and each cylinder 19 is equipped with a piston 16 that reciprocates in the cylinder 19. The piston 16 is connected to the crankshaft 17 through a connecting rod 16a.
The upper portion of the combustion chamber B of the cylinder 19 is formed by recessing the lower surface of the cylinder head 10H facing the cylinder 19, but in this embodiment, the upper portion of the combustion chamber B has a triangular roof shape. It is formed in a pent roof type. A pair of intake ports 11A, 11B (first intake port 11A, second intake port 11B) are connected to one slope of the triangular roof, and a pair of exhaust ports 12A, 12B (first The exhaust port 12A and the second exhaust port 12B) are connected.

A spark plug 13 is provided at the center of the top of the triangular roof with its tip protruding to the combustion chamber B side.
The intake ports 11A and 11B are provided with intake valves 14A and 14B (first intake valve 14A and second intake valve 14B), and combustion of the intake ports 11A and 11B is performed by reciprocating drive of the intake valves 14A and 14B. The intake ports 11A, 11B and the combustion chamber B are communicated or shielded by opening / closing operation at the locations (intake ports) 11a, 11b (first intake port 11a, second intake port 11b) facing the chamber B.

  Similarly, the exhaust ports 12A and 12B are respectively provided with exhaust valves 15A and 15B (first exhaust valve 15A and second exhaust valve 15B), and the exhaust ports 12A and 12B are driven by reciprocating drive of the exhaust valves 15A and 15B. The exhaust ports 12A and 12B and the combustion chamber B communicate with each other or are shielded by opening and closing at the locations (exhaust ports) 12a and 12b (first exhaust port 12a and second exhaust port 12b) facing the combustion chamber B of 12B. Is done.

[Intake and exhaust system configuration]
The pair of intake valves 14A and 14B are opened / closed synchronously (simultaneously) or with a phase difference by a valve mechanism, and the pair of exhaust valves 15A and 15B are opened / closed synchronously (simultaneously).
The first intake valve 14A and the second intake valve 14B are poppet valves each having a cap portion formed at the lower end thereof, and each cap portion opens and closes the first intake port 11a or the second intake port 11b. . Similarly, the first exhaust valve 15A and the second exhaust valve 15B are also poppet valves in which a cap portion is formed at the lower end, and each cap portion has a first exhaust port 12a or a second intake port 11b. Open and close.

  The upper ends of the first intake valve 14A and the second intake valve 14B are in contact with one end of the rocker arm 35, and the upper ends of the first exhaust valve 15A and the second exhaust valve 15B are respectively connected to the rocker arm 37. It abuts on one end. The rocker arms 35 and 37 are swing members pivotally supported on the rocker shaft, and the intake valve 14 and the exhaust valve 15 are reciprocally driven by the swing of the respective rocker arms 35 and 37. By these reciprocating driving, each intake port 11A, 11B and the combustion chamber B are communicated or shielded, and each exhaust port 12A, 12B and the combustion chamber B are communicated or shielded. The other ends of the rocker arms 35 and 37 are provided with cams 36 and 38 that are pivotally supported by the camshaft. Thereby, the rocking | fluctuation pattern of the rocker arms 35 and 37 becomes a thing according to the shape (cam profile) of the cams 36 and 38. FIG.

  In the engine 10, the exhaust valves 15A and 15B are provided with a valve operating mechanism with a constant operation. The valve operating mechanism of the intake valves 14A and 14B is a variable valve operating variablely controlling the operation of the rocker arm 35 or the cam 36. Mechanism 6 is applied. The variable valve mechanism 6 is a valve mechanism that can individually change the valve opening / closing timing (valve timing) of the intake valves 14A and 14B. The variable valve mechanism 6 includes a variable valve timing mechanism 6a configured as a mechanism for changing the swing timing of the rocker arm 35, for example.

  The variable valve timing mechanism 6a is a mechanism for changing the valve opening / closing timing of the intake valves 14A and 14B. The variable valve timing mechanism 6a has a function of changing the rotational phase of the cam 36 or the cam shaft that causes the rocker arm 35 to swing. By changing the rotational phase of the cam 36 or the camshaft, it is possible to continuously shift (shift) the swing timing of the rocker arm 35 with respect to the rotational phase of the crankshaft 17.

  Here, as the variable valve mechanism 6, the valve opening / closing timing is simply changed (shifted) back and forth without changing the cam profile itself, that is, the valve opening / closing timing is changed (shifted) back and forth. Although the lift amount is not changed, a variable valve mechanism of a type that changes the valve lift amount in conjunction with the opening / closing timing of the valve may be used.

  As shown in FIG. 2, the intake port portion 11 having intake ports 11A and 11B includes a single intake port upstream portion 11C that is connected to an upstream intake manifold 20 (see FIG. 1, hereinafter referred to as an intake manifold), The first intake port 11 </ b> A and the second intake port 11 </ b> B are branched from the one intake port upstream portion 11 </ b> C and extend to locations facing the combustion chamber B of the cylinder 19. Here, the first intake port 11A and the second intake port 11B are formed symmetrically with each other.

  The first intake port 11A has a first intake port 11a at a location facing the combustion chamber B at the downstream end of the intake flow, and the air in the first intake port 11A passes through the first intake port 11a. To the combustion chamber B. Similarly, the second intake port 11B has a second intake port 11b at a location facing the combustion chamber B at the downstream end of the intake flow, and the air in the second intake port 11B is the second intake port. It is supplied to the combustion chamber B through the port 11b. The intake ports 11a and 11b of these intake ports 11A and 11B are formed on one slope of a triangular roof formed in the upper part of the combustion chamber B.

The first intake port 11A is provided with a first intake valve 14A, and the second intake port 11B is provided with a second intake valve 14B. The first intake valve 14A and the second intake valve 14B are poppet valves having a cap portion formed at the lower end thereof, and the cap portion opens and closes the first intake port 11a or the second intake port 11b.
The first intake port 11A is provided with a first injector (first fuel injection means) 18A, and the second intake port 11B is provided with a second injector (second fuel injection means) 18B. It is done. That is, the engine 10 of the present embodiment is an engine (also referred to as a multi-port injection engine) in which injectors 18A and 18B are provided for the intake ports 11A and 11B.

Here, the first intake valve 14A and the second intake valve 14B are also arranged symmetrically with each other, and the first injector 18A and the second injector 18B are also arranged symmetrically with each other.
Further, the exhaust port portion 12 having the exhaust ports 12A and 12B includes a first exhaust port 12A and a second exhaust port 12B extending downstream from the portion facing the combustion chamber B of the cylinder 19, respectively. The first exhaust port 12A and the second exhaust port 12B are joined together to form an exhaust port downstream portion 12C that is connected to a downstream exhaust manifold 30 (see FIG. 1, hereinafter referred to as an exhaust manifold). Here, the first exhaust port 12A and the second exhaust port 12B are formed symmetrically with each other.

  The first exhaust port 12A has a first exhaust port 12a at a location facing the combustion chamber B at the upstream end of the exhaust flow, and the first exhaust port 12A is connected to the first exhaust port 12A via the first exhaust port 12a. Exhaust gas is discharged from the combustion chamber B. Similarly, the second exhaust port 12B has a second exhaust port 12b at a location facing the combustion chamber B at the upstream end of the exhaust flow, and the second exhaust port 12B has the second exhaust port 12b. Exhaust gas is discharged from the combustion chamber B via The exhaust ports 12a and 12b of these exhaust ports 12A and 12B are formed on the other slope of the triangular roof formed in the upper part of the combustion chamber B.

The first exhaust port 12a is provided to face the first intake port 11a, and the second exhaust port 12b is provided to face the second intake port 11b. Here, “opposing” means facing each other across a one-dot chain line X corresponding to the ridgeline of the cylinder 19.
The first exhaust port 12A is provided with a first exhaust valve 15A, and the second exhaust port 12B is provided with a second exhaust valve 15B. The first exhaust valve 15A and the second exhaust valve 15B are poppet valves having a cap portion formed at the lower end thereof, and the cap portion opens and closes the first exhaust port 12a or the second exhaust port 12b.

Here, the first intake valve 14A and the second intake valve 14B are also arranged symmetrically.
As shown in FIG. 1, an intake manifold 20 is connected to an upstream side of the intake air flow of the intake port portion 11. A surge tank 21 for temporarily collecting intake air flowing to the intake port portion 11 is provided in the upstream portion of the intake manifold 20. The intake manifold 20 on the downstream side of the surge tank 21 is formed so as to branch toward each cylinder 19, and the surge tank 21 is located at the branch point. The surge tank 21 functions to reduce intake pulsation and intake interference generated in each cylinder 19.

  A throttle body 23 is connected to the upstream end of the intake manifold 20. An electronically controlled throttle valve 24 is built in the throttle body 23, and the amount of intake air flowing toward the intake manifold 20 is adjusted according to the opening (throttle opening) of the throttle valve 24. The throttle body 23 includes an actuator 23a that can operate the throttle valve 24 and change the throttle opening, and a throttle opening sensor 23b that detects the throttle opening. This throttle opening is adjusted by operating the actuator 23a based on the throttle opening detected by the throttle opening sensor 23b by the vehicle ECU 5.

An intake passage 25 is connected further upstream of the throttle body 23, and an air filter 28 is interposed upstream of the intake passage 25. As a result, the intake air filtered and collected by the air filter 28 is supplied to the cylinder 19 of the engine 10 via the intake passage 25, the intake manifold 20 and the intake port portion 11.
On the other hand, an exhaust manifold 30, an exhaust catalyst 32, and an exhaust passage 39 are provided downstream of the exhaust port portion 12 in the exhaust flow. The exhaust manifold 30 is formed so as to merge from each cylinder 19 and is connected to the exhaust passage 39 on the downstream side thereof. An exhaust catalyst 32 is interposed in the exhaust passage 39.

The exhaust catalyst 32 has a function of detoxifying HC (hydrocarbon), carbon monoxide, nitrogen oxide and the like contained in the exhaust, and is, for example, an oxidation catalyst or a three-way catalyst. HC in the exhaust discharged from the combustion chamber B of the engine 10 is oxidized and removed by the exhaust catalyst 32.
Further, the intake and exhaust system of the engine 10 is provided with a turbocharger (supercharger) 31 that supercharges intake air into the cylinder 19 using exhaust pressure. The turbocharger 31 is interposed across both the intake passage 25 and the exhaust passage 39, rotates the turbine 27 with the exhaust pressure in the exhaust passage 39, and drives the compressor 26 using the rotational force. Thus, the intake air in the intake passage 25 is compressed and supercharging is performed. An intercooler 29 is provided downstream of the intake air flow of the compressor 26 in the intake passage 25, and the compressed air is cooled.

[Detection system]
The crankshaft 17, a crank angle sensor (engine speed detector) 33 for detecting the rotation angle theta _CR is provided. The amount of change per unit of rotational angle theta _CR time is proportional to the rotational speed Ne of the engine 10. Therefore, it can be said that the crank angle sensor 33 has a function of detecting the rotational speed Ne of the engine 10. Information on the engine speed Ne detected or calculated here is transmitted to the vehicle ECU 5 described later. Based on the rotational angle theta _CR detected by the crank angle sensor 33, vehicle ECU5 calculates the engine rotational speed Ne.

An intake pressure sensor (intake pressure detection means) 22 for detecting the intake pressure P ₁ is provided on the downstream side of the throttle valve 24. The intake pressure sensor 22 detects the pressure in the surge tank 21 corresponding to the intake pressure flowing into the first intake port 11A or the second intake port 11B. The installation location of the intake pressure sensor 22 is not limited to this, and the intake pressure sensor 22 may be provided in each of the first intake ports 11A connected to each cylinder 19.

On the other hand, between the turbine 27 of the exhaust port 12a, 12b and the turbocharger 31 (e.g. confluence portion of the exhaust manifold 30), the exhaust pressure sensor 46 is provided to detect the exhaust pressure _{P 2} that flows out from the exhaust port 12A, 12B . This exhaust pressure sensor 46 detects the exhaust pressure P ₂ before passing through the turbine 27 corresponding to the exhaust pressure flowing out of the first exhaust port 12A or the second exhaust port 12B. The installation location of the exhaust pressure sensor 46 is not limited to this, and the exhaust pressure sensor 46 may be provided in any one or each of the exhaust ports 12A and 12B connected to each cylinder 19.

Information on the intake and exhaust pressures P ₁ and P ₂ detected by these sensors 22 and 46 is transmitted to the vehicle ECU 5.
Further, the vehicle, an accelerator position sensor 34 for detecting an accelerator opening theta _AC corresponding to the amount of depression of the accelerator pedal is provided. The accelerator opening θ _AC is a parameter corresponding to the driver's acceleration request, and corresponds to the required output torque to the engine 10. The accelerator opening theta _AC of information detected by the accelerator position sensor 34 is transmitted to the vehicle ECU 5.

Further, the vehicle is provided with an output torque sensor (output torque detection means) 40 that detects the actual output torque of the engine 10. In this embodiment, the output torque sensor 40 uses, for example, a magnetostrictive torque sensor provided on the periphery of the output end of the crankshaft 17, but the output torque sensor 40 is not limited to this. Information on the actual output torque detected by the torque sensor 40 is transmitted to the vehicle ECU 5.
The driving state of the vehicle can be detected by the intake pressure sensor 22, the exhaust pressure sensor 46, the crank angle sensor 33, the accelerator position sensor 34, and the output torque sensor 40 which are these detection system configurations (driving state detection means). .

[Control system]
The vehicle ECU 5 is an electronic control device including, for example, a microprocessor, a ROM, a RAM, an input / output circuit, and the like, and is connected to an electronic control device such as the throttle body 23, the variable valve mechanism 6 and various sensors. The intake pressure sensor 22, the exhaust pressure sensor 46, the crank angle sensor 33, the accelerator position sensor 34, the output torque sensor 40, and the throttle opening sensor 23b are connected to the vehicle ECU 5.

The vehicle ECU 5 connected to the various sensors acquires various information corresponding to the driving state of the vehicle by the various sensors.
Conventionally, a value obtained by performing appropriate processing such as moving average on the instantaneous value of information detected by various sensors to remove pulsation components is used for control. Instantaneous values are used for the pressure P ₁ and the exhaust pressure P ₂ .

In the present embodiment, using the instantaneous value detected by the intake pressure sensor 22 provided in the surge tank 19 as an intake pressure P _1. Further, for example, a instantaneous value detected by the exhaust pressure sensor 46 provided at the confluence portion of the exhaust manifold 30 as the exhaust pressure P _2.
That is, the vehicle ECU 5 acquires the instantaneous value P ₁ of the intake pressure and the instantaneous value P ₂ of the exhaust pressure that constantly fluctuate due to the influence of the pulsation detected by the intake pressure sensor 22 and the exhaust pressure sensor 46. Then, it uses the instantaneous value P ₂ of the instantaneous value P ₁ and the exhaust pressure of the intake pressure during the valve overlap period in which blow-by of the fuel occurs in the control.

That is, since the intake pressure P ₁ detected by the intake pressure sensor 22 includes the pulsation component of the intake air flowing into each cylinder 19, the vehicle ECU 5 detects the crank angle θ _CR detected by the crank angle sensor 33. It acquires the intake pressure P ₁ of the valve overlap period of each cylinder 19 based on. Similarly, since the exhaust pressure P ₂ detected by the exhaust pressure sensor 46 includes the pulsation component of the exhaust gas flowing out from each cylinder 19, the vehicle ECU 5 detects the crank angle detected by the crank angle sensor 33. It acquires exhaust pressure P ₂ of the valve overlap period of each cylinder 19 based on the theta _CR.

Note that the vehicle ECU 5 is a value obtained by subjecting the values detected by the sensors 22 and 46 to appropriate processing such as moving average when the instantaneous value as a value used for control is not sufficiently accurate. May be used for control as the intake pressure P ₁ and the exhaust pressure P ₂ .
Further, if the intake pressure sensor 22 is provided in each of the first intake ports 11A connected to each cylinder 19, the intake pressure detected by these intake pressure sensors 22 is the intake pressure in each intake port 11A. since is obtained by detecting the instantaneous value of the air pressure directly vehicle ECU5 is more preferred the use of instantaneous values P ₁ of the intake pressure in the first intake port 11A in the valve overlap period control. Similarly, if the exhaust pressure sensor 46 is provided in any one of the exhaust ports 12A and 12B connected to each cylinder 19, the exhaust pressure detected by these exhaust pressure sensors 46 is the exhaust ports 12A and 12B. since is obtained by detecting the instantaneous value of the exhaust pressure of the inner directly vehicle ECU5 it is more preferred the use exhaust ports 12A of the valve overlap period, the instantaneous value P ₂ of the exhaust pressure in 12B to the control.

The vehicle ECU 5 controls a wide range of systems such as an ignition system, a fuel system, an intake / exhaust system, and a valve system of the engine 10. Such control includes control of the amount of fuel injected from the injector 18 and the injection timing, the ignition timing by the spark plug 13, the valve timing of the intake valve 14, the opening of the throttle valve 24, and the like.
Of the control by the vehicle ECU 5 for various systems of the vehicle, the control performed according to the driving state of the vehicle will be described below.

  The vehicle ECU 5 includes a valve timing control unit (intake valve control unit) 1, a fuel injection control unit (fuel injection control unit) 2, a throttle opening as software that implements a function for performing control performed according to the driving state of the vehicle. An output shortage determination unit 4 having a degree control unit 3 and a required output torque calculation unit 4a is provided, and a map M in which a relationship between a driving state of the vehicle and a valve overlap period is set in advance is stored.

The valve timing control unit 1 controls the valve timing of the intake valve 14 by changing or maintaining the phase of the cam 36 or the camshaft via the variable valve timing mechanism 6a. The fuel injection control unit 2 controls the fuel injection timing of the injector 18. Throttle opening control section 3 controls the opening degree of the throttle valve 24 in response to the accelerator opening theta _AC. Moreover, it demanded output torque calculation unit 4a calculates the required output torque of the driver in accordance with the engine speed Ne detected by the accelerator opening theta _AC and a crank angle sensor 33 detected by the accelerator position sensor 34, the output The deficiency determination unit 4 compares the required output torque calculated by the required output torque calculation unit 4a with the actual output torque of the engine 10 detected by the output torque sensor 40, and the required output torque is greater than or equal to a predetermined value than the actual output torque. If it is larger, it is determined that the operating state (insufficient state) in which the output torque is insufficient.

In the map M, as illustrated in FIG. 3, the driving state of the vehicle, the valve overlap period corresponding to the driving state, and the specific operation region are defined in advance. More specifically, this map M uses the engine speed (engine speed) Ne and the differential pressure (P ₁ -P ₂ ) between the intake pressure P ₁ and the exhaust pressure P ₂ as arguments, and the valve overlap period and the specific operation. The area is defined in advance. The magnitude relationship between the valve overlap periods OL _{1 to} OL ₄ defined in this map M is OL ₁ <OL ₂ <OL ₃ <OL ₄ . In the region outside the valve overlap period OL ₁ (the plain region in FIG. 3), the overlap period is zero, that is, the opening of the intake valve 14 is started at the end of the opening of the exhaust valve 15, and the valve overlap period is Not set. Note that the "period" of the valve overlap period, different from the "time" timing of the valve overlap those defined by the crank angle theta _CR. Thus, the magnitude of the overlap period corresponds to the magnitude of the advance variation of the crank angle theta _CR corresponding to the opening period of the intake valve 14.

The valve overlap period in relation to the engine speed Ne is set so as to increase as the engine speed Ne increases in a region where the engine speed Ne is relatively low, and in a region where the engine speed Ne is relatively high. The engine speed Ne is set to decrease as the engine speed Ne increases.
In the region where the engine speed Ne is low, the actual time of the valve overlap period becomes longer than the region where the engine speed Ne is high even if the valve overlap period is the same. For this reason, in a region where the engine speed Ne is low, even if a small valve overlap period is defined, the actual time is long and sufficient charging efficiency is obtained. For the same reason, if the valve overlap period is excessively extended in the low rotation range, fuel blow-through increases. On the other hand, as the engine speed Ne increases, the intake charging efficiency can be improved using the inertia effect of intake and exhaust, so that the valve overlap period is set to be longer. On the other hand, in the case where the valve overlap period is changed by shifting the opening period of the intake valve back and forth as in this embodiment, the intake air is increased in order to increase the valve overlap period when the engine speed Ne is high to some extent. If the opening start timing of the valve is advanced, the opening end timing is also advanced, and if the opening end timing of the intake valve is advanced, the inertia effect of intake cannot be fully utilized and the charging efficiency is lowered. For this reason, in a region where the engine speed Ne is high, the valve overlap period is set smaller as the engine speed Ne becomes higher.

In the valve overlap period in relation to the differential pressure (P ₁ −P ₂ ) between the intake pressure P ₁ and the exhaust pressure P ₂ , the differential pressure is larger (the intake pressure P ₁ is greater than the exhaust pressure P ₂ ). In order to improve the filling efficiency, the valve overlap period is set larger as the differential pressure is larger.
Further, the specific operation region is defined as a region indicated by a thick broken line in FIG. In other words, the specific operation region, the intake air pressure P ₁ is greater state than the exhaust pressure P _2, and the engine speed Ne is a region within a predetermined range is defined. Here, as the predetermined range of the engine speed Ne, an engine speed range in which the charging efficiency can be reliably improved by increasing the valve overlap period is set.

The vehicle ECU 5 performs specific control when the driving state of the vehicle is in the specific driving region, and performs normal control when the driving state of the vehicle is not in the specific driving region.
In the specific control, the opening and closing timings of the intake valves 14A and 14B are individually controlled, and the fuel injection timings of the injectors 18A and 18B are individually controlled.
The valve timing control in the specific control is performed by the valve timing control unit 1. Thereby, the valve overlap period of each intake valve 14A, 14B can be controlled. That is, the valve timing control unit 1 performs control so that the valve overlap period of the first intake valve 14A is the valve overlap period (first period) determined using the map M described above. Control is performed so that the valve overlap period (second period) of the second intake valve 14B becomes zero.

The bubble timing in this specific control will be described below with reference to FIG.
FIG. 4 (a), the valve lift on the vertical axis, and defines a crank angle theta _CR on the horizontal axis represents the valve lift and valve timing of the valves 14 and 15, the operation of the first intake valve 14A Is indicated by a solid line, the operation of the second intake valve 14B is indicated by a one-dot chain line, and the operation of the exhaust valve 15 is indicated by a broken line.

The valve timings of the pair of exhaust valves 15A and 15B are opened and closed at the same timing. Here, the exhaust valve 15 starts to open at the crank angle θ ₁ and ends to open at the crank angle θ ₄ .
On the other hand, the valve timing of the first intake valve 14A is controlled so that the valve overlap period becomes the first period. That is, the first intake valve 14A is controlled to an opening start timing that is earlier than the opening end timing of the exhaust valve 15 by a first period. Here, the first intake valve 14A begins to open at crank angle theta _2, it is terminated open at crank angle theta _5. This first period is determined based on the map M described above, and can be said to correspond to the crank angles θ _{2 to} θ ₄ .

The valve timing of the second intake valve 14B is controlled so that the valve overlap period of the second intake valve 14B and the exhaust valve 15 becomes the second period. Here, the second intake valve 14B begins to open at crank angle theta _4, it is terminated open at crank angle theta _6. This second period is set to zero.
Next, fuel injection timing control in the specific control will be described. In this control of the fuel injection timing, the fuel injection control unit 2 controls the fuel injection timing of each injector 18A, 18B. That is, the fuel injection control unit 2 performs the fuel injection of the first injector 18A during the opening period of the first intake valve 14A, and the fuel injection of the second injector 18B during the closing period of the second intake valve 14B. Let it be implemented. An example of the fuel injection timing will be described with reference to FIG.

  Here, since the injectors 18A and 18B are provided at a distance from the upstream side of the intake air flow of the intake ports 11a and 11b, the fuel injected at the time of fuel injection passes through the intake ports 11a and 11b and is in the combustion chamber. The time point at which the exhaust ports 12a and 12b at B are reached is delayed. This delay time τ is not only different depending on the structure of the engine due to the shape of the intake port, the injectors 18A, 18B, the intake ports 11a, 11b, and the exhaust ports 12a, 12b, but also the engine speed Ne, the throttle opening degree, It changes according to the operating state of the engine 10 such as the intake air flow velocity which changes due to the operation of the supercharger. In the present embodiment, the relationship between the engine operating condition and the delay time τ under the engine structure to which the present control is applied is obtained experimentally and empirically in advance and stored in the vehicle ECU 5. In addition, the fuel injection control unit 2 is configured to acquire information on the engine operating status and to read the delay time τ according to the engine operating status.

The FIG. 4 (b), the respective injectors 18A, shows a fuel injection timing corresponding to the crank angle theta _CR of 18B, for the first injector 18A solid, shown by a dashed line for the second injector 18B.
The start of fuel injection by the first injector 18A is performed later than the start of fuel injection by the second injector 18B.

In addition, the injection timing from the injection start time of the first injector 18A to the injection end time is performed (intake stroke injection) during the period (open period) from the start of opening of the first intake valve 14A to the end of opening. .
Fuel injection timing of the first injector 18A, for example, the injected fuel reaches the first outlet 12a or the second exhaust port 12b in a closed timing of the exhaust valve 15 (corresponding to the crank angle theta ₄₎ Thus, fuel injection is started. At this time, the fuel injection control unit 2 sets a delay time τ between the fuel injection time point and the arrival time point of the injected fuel to the exhaust ports 12a and 12b according to the engine operating state, and as early as possible. Control of fuel injection by the first injector 18A is performed. Here, a one time corresponding to the crank angle theta ₃ through? ₄ corresponds to the delay time tau, to implement the fuel injection at the point corresponding to the crank angle theta _3. Accordingly, in the exhaust ports 12a and 12b, the overlapping period (first overlapping period T ₁ ) between the first period and the fuel injection by the first injector 18A is the second period and the fuel by the second injector 18B. It can be said that it is not more than the overlapping period (second overlapping period T ₂ ) with the injection.

  In the second injector 18B, as shown by a one-dot chain line in FIG. 4B, the start and end of fuel injection are performed before the second intake valve 14B is opened (closed period). FIG. 4B illustrates an example in which fuel injection by the second injector 18B is performed during the opening period of the exhaust valve 15 (exhaust stroke injection), but is not limited thereto, and the second intake valve 14B is not limited thereto. The closing period may be earlier or later than the illustrated period.

The vehicle ECU 5 performs output shortage control when the vehicle driving state is in the specific driving range and the output torque of the engine 10 is insufficient. That is, the vehicle ECU 5 performs the output shortage response control when the output torque of the engine 10 is insufficient during the specific control.
The lack of output torque of the engine 10, which is a precondition for this lack of output control, is determined by the output shortage determination unit 4. Specifically, when the output torque of the engine 10 is insufficient when the output torque of the engine 10 is smaller than the required output torque calculated by the required output torque calculation unit 4a by a predetermined value or more, the output shortage determination unit 4 judge. As the predetermined value used for the output shortage determination, a first predetermined value and a second predetermined value larger than the first predetermined value are set in advance.

The output shortage determination unit 4 determines that the output torque of the engine 10 is insufficient when the required output torque is greater than the first predetermined value than the output torque of the engine 10. In this case, the vehicle ECU 5 performs output shortage response control, but performs output shortage response control in accordance with the degree of output torque shortage.
That is, when the difference (Td−Tr) between the required output torque Td and the actual output torque Tr of the engine 10 is larger than the first predetermined value ΔT1 but smaller than the second predetermined value ΔT2, the intake valve 14 Control of valve timing and control of fuel injection timing of the injector 18A are performed. That is, the vehicle ECU 5 individually controls the opening and closing timings of the intake valves 14A and 14B through the valve timing control unit 1, and individually controls the fuel injection timings of the injectors 18A and 18B through the fuel injection control unit 2.

In this valve timing control, the valve timing control unit 1 determines that the valve overlap period (second period) of the second intake valve 14B is equal to the first period determined using the map M described above. The period 2 is increased, and the valve overlap period of the first intake valve 14A is also controlled to be the first period.
In this fuel injection timing control, the fuel injection control unit 2 performs the fuel injection timing of the first injector 18A during the opening period of the first intake valve 14A, and sets the fuel injection timing of the second injector 18B. This is performed during the opening period of the second intake valve 14B. For example, as shown by the solid line in FIG. 4B, the fuel injection control unit 2 causes the fuel injected by the injectors 18A and 18B to reach the exhaust ports 12a and 12b at the timing when the exhaust valve 15 is closed. As described above, the fuel injection is performed at the timing in consideration of the delay time τ.

  Further, when the difference (Td−Tr) between the required output torque Td and the actual output torque Tr of the engine 10 is larger than the second predetermined value ΔT2 (the actual output torque Tr of the engine 10 with respect to the required output torque Td is remarkably insufficient). In this case, the vehicle ECU 5 performs control for further increasing the opening of the throttle valve 24 in addition to the valve timing control for increasing the second period and the fuel injection control for performing the intake stroke injection. . The throttle opening correction control is performed by the throttle opening control unit 3 and is performed by operating the actuator 23a of the throttle body 23 based on the throttle opening detected by the throttle opening sensor 23b.

When the output shortage is resolved by these output shortage response controls, or when the engine speed Ne increases and the vehicle driving state deviates from the specific operation region, the output shortage response control is terminated.
Next, control (normal control) performed when the driving state of the vehicle is not in the specific driving region will be described.

In the normal control, the opening / closing timings of the intake valves 14A, 14B are controlled in synchronization with each other, and the fuel injection timings of the injectors 18A, 18B are controlled in synchronization with each other.
The valve timing control in the normal control is performed by the valve timing control unit 1 and each of the intake valves 14 has a synchronized valve overlap period. That is, the valve timing control unit 1 performs control so that the valve overlap period of the intake valve 14 becomes the valve overlap period determined using the map M described above. Of course, in an operating state of the vehicle where the valve overlap period is zero (not set), the valve timing control unit 1 starts opening the intake valve 14 when the exhaust valve 15 is opened. The valve timing of the exhaust valve 15 is not changed.

The fuel injection control in the normal control is performed by adjusting the fuel injection timing by both the injectors 18A and 18B by the fuel injection control unit 2. This control synchronizes (simultaneously) the fuel injection timings of the injectors 18A and 18B.
The fuel control unit 2 adjusts the fuel injection timing of the injectors 18A and 18B before the intake valve 14 is opened. That is, the intake valve 14 is opened after the fuel injection by the injectors 18A and 18B is completed, and the intake valve 14 is closed when the fuel injection by the injectors 18A and 18B is started.

[Action / Effect]
Since the engine control apparatus according to the first embodiment of the present invention is configured as described above, the control flow as shown in FIG. 5 is periodically performed by the vehicle ECU 5 at a predetermined control cycle (for example, every several tens of milliseconds). Done.
In step S10, the engine speed Ne, the intake pressure P ₁ , the exhaust pressure P ₂ , the accelerator opening θ _AC , the actual output torque Tr of the engine 10 and the request detected or calculated by each sensor 33, 22, 46, 40, 4a. Various information on the output torque Td is acquired.

In step S20, it is determined whether the driving state of the vehicle is in a specific driving region. This determination is made using various information acquired in step S10. If the driving state of the vehicle is the specific driving region, the process proceeds to step S30. If the driving state of the vehicle is not the specific driving region, the process proceeds to step S90.
In step 90, a normal control subroutine is executed. In this normal control subroutine, valve timing control and fuel injection control are performed, and the valve timings of both intake valves 14A and 14B are synchronized so that a valve overlap period determined by using the map M according to the driving state of the vehicle. Both the injectors 18A and 18B inject fuel before opening the intake valve 14 such as exhaust stroke injection.

In step S30, a specific control subroutine is executed. Although the details of this specific control subroutine are not shown, the valve timing control and the fuel injection timing control are performed, and the vehicle operating state (the intake pressure P ₁ is greater than the exhaust pressure P ₂ and the engine speed) is shown. The valve overlap period of the first intake valve 14A is a first period (that is, a valve overlap period determined by using the map M according to the driving state of the vehicle) according to Ne. And the valve overlap period of the second intake valve 14B is set to the second period (that is, zero). Further, the first injector 18A performs the intake stroke injection, and the second injector 18B performs the exhaust stroke injection.

  In step S40, it is determined whether the required output torque Td is greater than the first predetermined value ΔT1 with respect to the actual output torque Tr of the engine 10 detected by the output torque sensor 40. That is, it is determined whether or not the output torque of the engine 10 is insufficient (insufficient state). This determination is performed by the output shortage determination unit 4, and the actual output torque Tr of the engine 10 detected by the output torque sensor 40 is subtracted from the required output torque Td calculated by the required output torque calculation means 4 a, and this subtraction result When (Td−Tr) is larger than the first predetermined value ΔT1, it is determined that the output torque of the engine 10 is insufficient (insufficient state). If it is insufficient, the process proceeds to step S50. If it is not insufficient, the process returns.

In step S50, an output shortage response control subroutine is executed. Then return.
The output shortage response control subroutine in step S50 will be described with reference to FIG.
In step S52, it is determined whether the required output torque Td is greater than the second predetermined value ΔT2 with respect to the actual output torque Tr of the engine 10. This determination is performed by the output shortage determination unit 4 and is performed by subtracting the actual output torque Tr of the engine 10 detected by the output torque sensor 40 from the request output torque Td calculated by the request output torque calculation means 4a. . If the subtraction result (Td−Tr) is larger than the second predetermined value ΔT2, the process proceeds to step S54, and the subtraction result (Td−Tr) is equal to or smaller than the second predetermined value ΔT2. Control goes to step S56.

  In step S54, the valve timing, fuel injection timing, and throttle opening are controlled. That is, in the valve timing control, the valve overlap period (second period) of the second intake valve 14B is controlled to be equal to the first period, and the valve overlap period of the first intake valve 14A is also the first period. It controls to become the period of. Further, in the fuel injection timing control, control is performed so that the fuel injection by both the injectors 18A and 18B is performed during the opening period of both the intake valves 14A and 14B. Further, in the control related to the throttle opening, the opening of the throttle valve 24 is corrected to be increased by the throttle opening control 3, that is, the throttle opening of the throttle body 23 is increased so as to increase the throttle opening detected by the throttle opening sensor 23b. Actuator 23a is operated.

  In step S56, the valve timing and fuel injection timing are controlled. That is, in the valve timing control, the valve overlap period (second period) of the second intake valve 14B is controlled to be equal to the first period, and the valve overlap period of the first intake valve 14A is also the first period. It controls to become the period of. In the fuel injection timing control, control is performed so that fuel injection by both the injectors 18A and 18B is performed during the open period of both intake valves 14A and 14B. Then return.

Therefore, in the engine control apparatus of the present embodiment, when the driving state of the vehicle is in the specific operation region, the valve timing control unit 1 sets the opening period of the first intake valve 14A as the opening period of the exhaust valve 15 and the first period. Therefore, it is possible to secure the output torque by promoting the charging efficiency by using the blow-in of the intake air by the valve overlap.
Further, the valve timing control unit 1 does not overlap the opening period of the second intake valve 14B with the opening period of the exhaust valve 15, so that the fuel injected into the second intake port is blown out to the exhaust side due to valve overlap. And the mixing promotion time of the fuel injected into the second intake port 11B and the fresh air can be secured.

In addition, since the fuel injection by the first injector 18A is performed not in the closing period of the first intake valve before the valve overlap but in the opening period of the first intake valve, that is, in the intake stroke, after the valve overlap ends. Fuel can be supplied into the combustion chamber B, and blow-through HC can be reduced.
Even in the case of having a valve overlap period, if the injected fuel cannot pass through the exhaust ports 12a and 12b, the HC will not blow through. In the present embodiment, when the injected fuel reaches the exhaust ports 12a and 12b, the fuel injection is performed so that the exhaust valve 15 is closed, so that the HC can be prevented from being blown through.

  When the driving state of the vehicle is in the specific driving region, fuel is injected in the intake stroke at the first intake port 11A, so it is difficult to ensure the mixing promotion time of the fuel and fresh air. 2, since fuel injection by the second injector 18B is performed during the closing period of the second intake valve 14B, only the time until the injected fuel enters the combustion chamber B due to the opening of the second intake valve 14B. The mixing promotion time of the fuel and the fresh air can be ensured for a long time, and the air-fuel mixture whose mixing entering the combustion chamber B from the second intake port 11B is promoted is combusted from the first intake port 11A. Mixing of fuel and fresh air entering the chamber B is also promoted, and combustion can be performed satisfactorily.

When the intake pressure P ₁ is larger than the exhaust pressure P ₂ , HC blow-through is likely to occur. However, when the intake pressure P ₁ is smaller than the exhaust pressure P ₂ , HC blow-through hardly occurs or does not occur. . In the present embodiment, since the intake air pressure P ₁ which blow-by of HC occurs to a specific operating region is larger than the exhaust pressure P _2, by appropriately controlling the fuel injection timing of the first injector 18A, the blow-by of HC Can be reduced.

Since the engine speed range in which the charging efficiency can be reliably improved by the valve overlap is within the predetermined operating range, the charging efficiency can be improved and the blow-through HC can be effectively reduced.
If the actual output torque Tr of the engine 10 is insufficient when the driving state of the vehicle is in the specific operation region, output shortage control is performed. In this output shortage response control, when the difference (Td−Tr) between the required output torque Td and the actual output torque Tr of the engine 10 is larger than the first predetermined value ΔT1 but smaller than the second predetermined value ΔT2. The valve timing control unit 1 performs control to increase the valve overlap period of the second intake valve 14B from the second period to the first period, and the fuel injection unit 2 performs intake stroke injection to both the injectors 18A and 18B. Therefore, the charging efficiency can be further improved and the blow-through HC can be reduced. Further, when the difference (Td−Tr) between the requested output torque Td and the actual output torque Tr of the engine 10 is larger than the second predetermined value ΔT2 (the actual output torque Tr is remarkably insufficient with respect to the requested output torque Td). In addition to the valve timing control for increasing the second period and the fuel injection control for performing the intake stroke injection, the throttle opening control unit 3 increases the opening of the throttle valve 24 in the opening direction. Therefore, the shortage of output torque can be resolved.
Upstream of the first air intake port 11A and the second intake ports 11B, since the turbocharger 31 for feeding to force air provided, intake air pressure P ₁ is likely to be greater than the exhaust pressure P _2, the filling of the intake Efficiency can be further improved to ensure output torque.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. The engine control apparatus according to the second embodiment of the present invention differs from the first embodiment in the fuel injection timing and the valve overlap period in the specific control.

Except for the points described here, the configuration is the same as that of the first embodiment, and for these, the same reference numerals are used and description of each part is omitted.
First, valve overlap in specific control will be described. This valve overlap is an overlap between the opening period of each of the intake valves 14A and 14B and the opening period of the exhaust valve 15, and is controlled by the valve timing control unit 1 of the vehicle ECU 5. An example of these valve opening / closing timings will be described with reference to FIG.

In FIG. 7 (a), the valve lift on the vertical axis, and defines a crank angle theta _CR on the horizontal axis represents the valve lift and valve timing of each valve 14, 15 in a particular control, the first intake valve 14A Is indicated by a solid line, the operation of the second intake valve 14B is indicated by a one-dot chain line, and the operation of the exhaust valve 15 is indicated by a broken line.
The valve timings of the pair of exhaust valves 15A and 15B are opened and closed at the same timing. Here, these exhaust valves 15 start to open at the crank angle θ ₁ ′, and end to open at the crank angle θ ₄ ′.

On the other hand, the valve timing of the first intake valve 14A is controlled such that the valve overlap period becomes a predetermined first period. That is, the opening of the first intake valve 14A is started earlier than the opening end timing of the exhaust valve 15 by the first period. Here, the opening of the first intake valve 14A is started at the crank angle θ ₂ ′, and the opening is ended at the crank angle θ ₅ ′. This first period is determined based on the map M as in the first embodiment, and corresponds to the crank angles θ ₂ ′ to θ ₄ ′.

Further, the valve timing of the second intake valve 14B is controlled so that the valve overlap period of the second intake valve 14B and the exhaust valve 15 becomes a predetermined second period. Here, the second intake valve 14B is _'started to open at crank angle theta _6' crank angle theta ₃ is terminated open at. This second period is shorter than the first period (the valve overlap period of the first intake valve 14A) and can be said to correspond to the crank angles θ ₃ ′ to θ ₄ ′.

Next, the fuel injection timing in the specific control will be described. The fuel injection timing is controlled by the fuel injection control unit 2 of the vehicle ECU 5 by controlling the fuel injection timing of each injector 18A, 18B. An example of the fuel injection timing will be described with reference to FIG.
The FIG. 7 (b), the respective injectors 18A corresponding to the crank angle theta _CR, shows a fuel injection timing of 18B, for the first injector 18A solid, shown by a dashed line for the second injector.

The fuel injection by the first injector 18A is performed later than the fuel injection by the second injector 18B. That is, the start time of the fuel injection by the first injector 18A is later than the start time of the fuel injection by the second injector 18B, and the end time of the fuel injection by the first injector 18A is the second injector 18B. Later than the end of the fuel injection time. Further, the overlap period (first overlap period T ₁ ) between the first period and the fuel injection by the first injector 18A is zero, and the overlap period between the second period and the fuel injection by the second injector 18B. Since (second overlap period T ₂ ) is zero, it can be said that the first overlap period T ₁ is equal to or shorter than the second overlap period T ₂ .

  FIG. 7B illustrates an example in which fuel injection by both the injectors 18A and 18B is performed in the exhaust stroke, but the fuel injection by the first injector 18A is more than the fuel injection by the second injector 18B. The valve overlap period of the first intake valve 14A and the fuel injection period of the first injector 18A do not overlap, and the valve overlap period of the second intake valve 14B and the second injector If the fuel injection period of 18B does not overlap, the fuel injection period by both the injectors 18A and 18B may be earlier or later than the period shown in FIG.

Other configurations are the same as those of the first embodiment.
In general, if the fuel injection timing is advanced, the fuel adhering to the wall of the port immediately after the injection is vaporized and mixing with the air is promoted. On the other hand, part of the air-fuel mixture passes through the combustion chamber due to valve overlap. When the exhaust port is blown through, the fuel is sufficiently contained in the air-fuel mixture, and the amount of blow-through fuel increases.

On the other hand, if the fuel injection timing is delayed, vaporization of the fuel adhering to the port wall surface immediately after injection is delayed, so mixing with air is also delayed. On the other hand, during the valve overlap period, vaporization was delayed due to adhesion to the port wall surface. Part of the air-fuel mixture that does not contain some fuel, such as fuel, passes through the combustion chamber and blows into the exhaust port 15, thereby reducing the amount of blown fuel.
In addition, if the valve overlap is lengthened, the charging efficiency of the intake air is improved. On the other hand, the air-fuel mixture is blown out to the exhaust port due to the valve overlap.

  On the other hand, the fuel injection control unit 2 of the second embodiment performs the fuel injection by the first injector 18A later than the fuel injection by the second injector 18B. With respect to, since the valve overlap period is long (the first period is longer than the second period), the amount of air blown into the exhaust port 15 of the air-fuel mixture is large, but the fuel in the air-fuel mixture is the first intake port. The amount of fuel remaining in the first intake port 14A as droplets due to adhesion to the 14A wall surface or the like is reduced by the amount of fuel that is delayed in vaporization, so that blow-through HC can be reduced. As for the intake air of the second intake port 14B, a part of the air-fuel mixture containing a sufficient amount of fuel and having a relatively high fuel concentration passes through the combustion chamber B and blows into the exhaust port 15, but the valve overlap. Since the period is short (the second period is shorter than the first period), the amount of the air-fuel mixture blown into the exhaust port 15 is small, and the blow-through HC can be reduced.

In the engine control apparatus of the second embodiment, the valve timing control unit 1 controls the opening period of the first intake valve 14A so that it overlaps the opening period of the exhaust valve 15 only by the first period. It is possible to secure the output torque by promoting the charging efficiency by utilizing the blow-in of the intake air due to the overlap.
In addition, since the fuel injection by the second fuel injection unit 18B is performed earlier than the fuel injection by the first fuel injection unit 18A, it is intended to promote vaporization of the injected fuel and mixing with fresh air. Can do.

Further, the valve timing control unit 1 causes the opening period of the second intake valve 14B to overlap with the opening period of the exhaust valve 15 for a second period shorter than the first period, so that the injection to the second intake port 14B. It is possible to suppress the situation where the discharged fuel blows through to the exhaust side due to the valve overlap, and the blow-through HC can be reduced.
Further, since the first overlap period T ₁ and a second overlap period T ₂ is zero, that is, the fuel injected during the valve overlap is not performed, the quick intake flow during the valve overlap period in which the intake velocity is increased No fuel is injected. Thereby, mixing of fuel and air is promoted, and an increase in the amount of fuel through which the air-fuel mixture in which the fuel is sufficiently mixed blows out to the exhaust port can be suppressed.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG. The engine control apparatus according to the third embodiment of the present invention differs in fuel injection timing from that of the second embodiment.
The valve overlap of the third embodiment is the same as that of the second embodiment, and will be described with reference to FIG.

Except for the points described here, the configuration is the same as in the first or second embodiment, and the same reference numerals are used for these, and the description of each part is omitted.
The FIG. 7 (c), the respective injectors 18A corresponding to the crank angle theta _CR, shows a fuel injection timing of 18B, for the first injector 18A solid, shown by a dashed line for the second injector.

  The start time of fuel injection by the first injector 18A is later than the start time of fuel injection by the second injector 18B, and the end time of fuel injection by the first injector 18A is the fuel time by the second injector 18A. Slower than the end of injection. That is, the fuel injection by the first injector 18A is performed later than the fuel injection by the second injector 18B.

A part of the fuel injection timing of the first injector 18A overlaps the first period (period corresponding to the crank angles θ ₂ ′ to θ ₄ ′). During this period (also referred to as a _first overlap period T1), the first injector 18A performs fuel injection during the valve overlap period of the first intake valve 14A.
A part of the fuel injection timing of the second injector 18B overlaps the second period (period corresponding to the crank angles θ ₃ ′ to θ ₄ ′). In this period (also referred to as _second overlap period T2), the second injector 18B performs fuel injection during the valve overlap period of the second intake valve 14B. Here, the end time of the fuel injection by the second injector 18B corresponds to the crank angle θ ₄ ′, and the start time is earlier than the time corresponding to the crank θ ₃ ′.

These overlapping periods, a first of the shorter overlap period T ₁ than the magnitude relation the second overlap period T _2. In other words, the fuel injection control unit 2 controls the second overlap period T ₂ to be shorter than the first overlap period T _1.
Therefore, since the second period is shorter than the first period, even if the period of fuel injection by the second injector 18B and the second period overlap, the period of the fuel injection and the second period The overlap period can also be limited by a short valve overlap period.

On the other hand, the first period is longer than the second period, but the fuel injection control unit 2 makes the first overlapping period T ₁ shorter than the second overlapping period T ₂ , and thus the first overlapping period. T _{1 is} also limited. Therefore, an increase in the blow-by fuel amount is suppressed. Thereby, blow-through HC can be reduced.
In the third embodiment, the fuel injection period by the second injector 18B is partially overlapped over the entire period of the second period. However, the fuel injection period by the second injector 18B is one part. The part may overlap with a part of the second period, and the overlapping period (second overlapping period T ₂ ) may be shorter than the first overlapping period T ₁ .

Further, the end point of the fuel injection by the second injector 18B is the same as the end point of opening of the exhaust valve 15 (the point corresponding to the crank angle θ ₄ ′). However, the end point is not limited to this. It is a later time point (a time point corresponding to between crank angle θ ₄ ′ and crank angle θ ₆ ′), and second overlap period T ₂ may be shorter than _first overlap period T _1. .

[Others]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.
In the embodiment described above, in a vehicle equipped with a turbocharger 31, is used an argument to the intake pressure P ₁ and the exhaust pressure P ₂ of the pressure difference of the map M (P 1 _{-P 2),} not provided with the turbocharger 31 the engine of the naturally aspirated, omitted exhaust pressure sensor 46, may be used a pressure differential of arguments to the intake pressure P ₁ and the atmospheric pressure P _a in the map M (P 1 _{-P a).} That is, in the naturally aspirated engine without a turbocharger 31, without exhaust gas is compressed between the exhaust port and the turbocharger turbine, exhaust pressure is equal to P _A to substantially atmospheric pressure. Therefore, the exhaust pressure sensor 46 can be omitted.

Further, in place of the intake sensor 22 and the exhaust pressure sensor 46, or in addition (for calculating a value corresponding to the differential pressure of the intake pressure P ₁ and the exhaust pressure P ₂ in the vehicle ECU 5) for estimating the driving state of the engine 10 configuration It is good. For example, in the engine with a turbocharger 31, generally to a differential pressure of the intake pressure P ₁ and the exhaust pressure P ₂ becomes positive by performing supercharging. Therefore, the differential pressure can be estimated without using the exhaust sensor 46.

Further, in place of the intake sensor 22 and the exhaust pressure sensor 46, a pre-specified operating range in which the intake pressure P ₁ during the valve overlap is higher than the exhaust pressure P ₂ (engine speed, and intake air flow) to the vehicle ECU5 These sensors 22 and 46 may be saved by storing them.
In addition, regarding the valve timing of the specific control, the second period (zero) in which the valve overlap period of the second intake valve 14B is not overlapped is shown. However, if the second period is smaller than the first period, Well, valve overlap may be implemented. According to this, it is possible to balance the improvement of the filling efficiency and the reduction of the blow-through HC.

When the second period is larger than zero and smaller than the first period as described above, the valve overlap period (first period) defined in the map M is set to a correction coefficient smaller than 1, for example. It can correct | amend and use it by multiplying.
In the output shortage control, the valve overlap period of the second intake valve 14B is changed from the second period to the first period, but the period after the change is the first period. What is necessary is just to make it larger than the 2nd period before a change within the range. That is, the phase difference between the reference phase and the opening / closing phase of the second intake valve 14B may be reduced with reference to the opening / closing phase of the first intake valve 14A. Accordingly, the second intake valve 14B increases the valve overlap period, can improve the charging efficiency, and can secure the output torque.

In addition, the valve mechanism that includes the rocker arms 35 and 37 is shown as the valve mechanism for opening and closing the valve. However, the present invention is not limited to this, and the present control device can also be applied to a cam direct-acting valve mechanism. .
Further, the delay time τ indicates the time for the fuel injected at the fuel injection time to reach the exhaust ports 12a and 12b from the combustion chamber B through the intake ports 11a and 11b. The time until the injected fuel passes through the intake ports 11a and 11b with respect to the injection time may be the delay time. This delay time varies depending on the structure of the engine such as the shape of the intake port, the positional relationship between the injectors 18A and 18B and the intake ports 11a and 11b, and the intake air that changes depending on the engine speed Ne, the throttle opening, the operation of the turbocharger, and the like. It will vary depending on the operating conditions of the engine 10 such as the flow velocity.

Further, in the above embodiment, although the delay time tau, not limited to this, period and may be the corresponding delay period defined by the crank angle theta _CR.
Moreover, although what fixed the valve timing of the exhaust valve 15 was shown, you may variably control the valve timing of this exhaust valve.

  The engine control device of the present invention can be applied not only to automobiles but also to vehicles equipped with a multi-port injection engine of a 4-cycle internal combustion engine.

1 Valve timing control unit (intake valve control means)
2 Fuel injection control unit (fuel injection control means)
3 Throttle opening control unit 4a Required output torque calculation unit (Required output torque calculation means)
6 Variable valve mechanism 10 Engine 11 Intake port portion 11A First intake port 11B Second intake port 12 Exhaust port portion 12A First exhaust port 12B Second exhaust port 14A First intake valve 14B Second intake air Valve 15 Exhaust valve 18 Injector (fuel injection means)
18A 1st injector (1st fuel-injection means)
18B 2nd injector (2nd fuel-injection means)
19 cylinders
22 Intake pressure sensor (Intake pressure detection means)
31 Turbocharger (supercharger)
33 Crank angle sensor (rotational speed detection means)
34 Accelerator position sensor (Accelerator opening detection means)
40 Output torque sensor (output torque detection means)
46 Exhaust pressure sensor

Claims (5)

A first intake valve that opens and closes an intake port to the combustion chamber in the first intake port;
A second intake valve for opening and closing an intake port to the combustion chamber in a second intake port;
An exhaust valve for opening and closing an exhaust port to the combustion chamber at an exhaust port;
First fuel injection means provided in the first intake port;
Second fuel injection means provided in the second intake port;
An operating state detecting means for detecting the operating state of the engine;
Intake valve control means for individually controlling the opening and closing timing of each intake valve based on detection information by the operating state detection means;
An engine control device having fuel injection control means for individually controlling the fuel injection timing by each of the fuel injection means based on detection information by the operating state detection means,
When the operation state detected by the operation state detection means is a specific operation region, the specific control is performed,
In the specific control,
The intake valve control means performs a valve overlap that overlaps the opening period of the first intake valve and the opening period of the exhaust valve only during the first period, and also opens the opening period of the second intake valve. Do not perform valve overlap that overlaps the opening period of the exhaust valve or perform it for a second period shorter than the first period,
The fuel injection control means has the exhaust valve closed when fuel injected by the first fuel injection means reaches the exhaust port from the combustion chamber via the intake port of the first intake port. controls the timing of fuel injection by the first fuel injection means so that, overlapping period between the arrival time to the exhaust port of the injected fuel by the said first period the first fuel injection means, wherein Fuel injection by the first fuel injection means is performed by the second fuel injection means so as to be equal to or less than an overlap period between the second period and the arrival period of the fuel injected by the second fuel injection means to the exhaust port. The engine control device is implemented later than the fuel injection by the engine. In the specific control,
The fuel injection control means performs fuel injection by the first fuel injection means during an opening period of the first intake valve, and performs fuel injection by the second fuel injection means to close the second intake valve. The engine control device according to claim 1, wherein the engine control device is implemented during a period. The operating state detection means includes an engine speed detection means for detecting the engine speed and an intake pressure detection means for detecting an intake pressure.
In the specific operation region, the engine speed detected by the engine speed detecting means is within a predetermined range, and the intake pressure detected by the intake pressure detecting means is equal to or higher than an exhaust pressure flowing out from the exhaust port. The engine control device according to claim 1, wherein the engine control device is an operation region of Request output torque calculation means for calculating the driver's request output torque, and output torque detection means for detecting the actual output torque of the engine,
When the actual output torque of the engine detected by the output torque detecting means is insufficient with respect to the required output torque calculated by the required output torque calculating means, the detected state detected by the operating state detecting means Even if the operating state of the engine is in the specific operating region, the output shortage control is performed,
In the output shortage response control,
The intake valve control means controls to increase the second period within the range of the first period;
The engine control apparatus according to claim 2 or 3, wherein the fuel injection control means performs fuel injection by the second fuel injection means during an open period of the second intake valve . A compressor is provided on the upstream side of the first and second intake ports,
The operating state detecting means further includes an exhaust pressure detecting means for detecting the exhaust pressure before passing through a turbine connected to the compressor and provided in an exhaust passage,
In the specific operation region, the engine speed detected by the engine speed detecting means is within a predetermined range, and the intake pressure detected by the intake pressure detecting means is detected by the exhaust pressure detecting means. It is an operation region above the exhaust pressure.
Characterized the this, the engine control apparatus according to claim 3 or 4, wherein.

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