WO2019163892A1

WO2019163892A1 - Internal combustion engine control device and intake system

Info

Publication number: WO2019163892A1
Application number: PCT/JP2019/006571
Authority: WO
Inventors: 真一平岡; 幸敏信田; 亀田　康寿
Original assignee: 株式会社デンソー
Priority date: 2018-02-23
Filing date: 2019-02-21
Publication date: 2019-08-29

Abstract

A combustion chamber (12) of an internal combustion engine (10) has a circular inner peripheral surface, and communicates with an intake port (20) via two intake openings (21) and with an exhaust port (14) via an exhaust opening (13). The internal combustion engine (10) is provided with: an ignition plug (16) disposed at the center of a ceiling portion covering the combustion chamber (12), and an airflow adjusting portion (50) for adjusting an airflow generated in the combustion chamber (12). This control device (60) for the internal combustion engine (10) is provided with: a drift current determination unit which determines that a drift current be generated by strengthening the airflow at the position of the ignition plug (16) compared to the airflow at other positions; and a control unit which causes the airflow adjusting portion (50) to generate a drift current if it is determined that a drift current be performed.

Description

Control device and intake system for internal combustion engine

Cross-reference of related applications

This application is based on Japanese Application No. 2018-031321 filed on Feb. 23, 2018 and Japanese Application No. 2018-149776 filed on Aug. 8, 2018. Is used.

The present disclosure relates to a control device for an internal combustion engine and an intake system using the control device.

In internal combustion engines, in order to promote combustion, the air flow in the combustion chamber is strengthened. If the airflow in the combustion chamber is increased, the arc discharge may be interrupted by the strong airflow when the ignition plug is ignited, and there is a risk of misfire. Therefore, in the technique of Patent Document 1, misfire is suppressed by increasing the discharge energy when the spark plug discharges in a state where the airflow is strong.

JP 2010-116880 A

Although the discharge interruption due to the air flow enhancement can be dealt with by increasing the discharge energy as described above, in addition to the above, turbulence may be generated around the spark plug as a cause of deterioration of the fuel ignitability in the cylinder. Conceivable. There is room for improvement in this regard.

The present disclosure has been made in view of the above problems, and a main object thereof is to provide a control device for an internal combustion engine capable of performing stable ignition.

In the first means, the inner peripheral surface has a circular shape, communicated with the intake port via two intake ports, and communicated with the exhaust port via the exhaust port, and the combustion chamber A control device applied to an internal combustion engine comprising an ignition plug provided at a central portion of a ceiling portion covering the airflow and an airflow adjustment unit for adjusting an airflow generated in the combustion chamber, wherein the airflow at the position of the ignition plug is A drift determination unit that determines that the drift is generated by strengthening compared to the air flow at other positions, and the drift adjustment unit generates the drift when the drift determination unit determines that the drift is performed. And a control unit.

¡When airflow flows into the combustion chamber from the two inlets, turbulence is generated at the position of the spark plug. This turbulent flow causes a short circuit in a state where the arc discharge of the spark plug is distorted, so that a sufficient discharge distance cannot be obtained. As a result, the fuel is ignited. As a result of analyzing the causes of such turbulent flow, the airflow flowing in from the suction port hits the inner peripheral wall surface of the combustion chamber and gathers in the center along the shape of the combustion chamber. A turbulent flow is generated by the collision of the airflow directed toward the side and the airflow returned to the inner peripheral wall surface.

Therefore, in the first means, in the airflow from the intake side to the exhaust side, it is determined that the airflow at the position of the spark plug is strengthened compared to the airflow at other positions to cause a drift. And when it determines with producing a drift, the airflow adjustment part is controlled so that a drift may be produced. In this way, by causing a drift in which the airflow at the position of the ignition plug in the combustion chamber is strengthened, the airflow at the position of the ignition plug first hits the inner peripheral wall of the combustion chamber and goes outward along its shape. Generation of turbulence at the spark plug position is suppressed. Therefore, even in a situation where the ignitability tends to become unstable, the airflow in the vicinity of the spark plug is stabilized, the short circuit of the arc discharge can be suppressed, and the ignitability can be ensured. That is, the ignitability can be ensured while ensuring the airflow necessary for fuel promotion.

The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. The drawing
FIG. 1 is a schematic configuration diagram of a control system for an internal combustion engine according to a first embodiment. FIG. 2 is a plan view of the intake port and the combustion chamber, FIG. 3 is a diagram for explaining the air flow in the combustion chamber. FIG. 4 is a diagram for explaining the air flow at the spark plug position. FIG. 5 is a perspective view of a rotary valve, FIG. 6 is a sectional view of the rotary valve, FIG. 7 is a diagram showing the open / close state of the rotary valve and the air flow, FIG. 8 is a schematic cross-sectional view showing the air flow in the combustion chamber in a state where the flow is uneven, FIG. 9 is a flowchart executed by the control device. FIG. 10 is a diagram showing the engine rotational speed, the load, and the degree of drift. FIG. 11 is a flowchart for performing feedback control. FIG. 12 is a diagram showing the relationship between in-cylinder flow and arc maintenance time, FIG. 13 is a diagram showing the relationship between arc maintenance time and ignition timing, FIG. 14 is a diagram showing the relationship between the in-cylinder flow and the main combustion period, FIG. 15 is a diagram showing the relationship between the ignition timing and the main combustion period, FIG. 16 is a perspective view of a rotary valve in the second embodiment, FIG. 17 is a diagram showing an open / close state of the rotary valve, FIG. 18 is a view for explaining the airflow in the intake port. FIG. 19 is a view for explaining the airflow in the intake port in a state where the guide portion is provided in the third embodiment. FIG. 20 is a front view of the guide portion and the rotary valve, FIG. 21 is a perspective view of a current plate, FIG. 22 shows a modified example of the guide portion. FIG. 23 is a schematic view of a pinball type valve element in another embodiment, FIG. 24 is a schematic view of an airflow adjusting unit in another embodiment, FIG. 25 is a schematic diagram of an airflow adjusting unit in another embodiment.

<First Embodiment>
Hereinafter, the first embodiment will be described with reference to FIGS. 1 to 15. In the following embodiments, parts that are the same or equivalent to each other are given the same reference numerals in the drawings, and the description of the same reference numerals is used.

In the first embodiment, an engine control system is constructed for an in-vehicle multi-cylinder four-cycle gasoline engine that is an internal combustion engine. FIG. 1 shows a schematic configuration diagram of the entire engine control system, particularly an intake system. In the following drawings, only one cylinder among a plurality of cylinders provided in the engine 10 is illustrated.

The piston 11 is accommodated in each cylinder of the engine 10 so as to be able to reciprocate. A combustion chamber 12 is provided on the top side of the piston 11 of each cylinder. The inner peripheral surface of the combustion chamber 12 has a circular cross section (perfect circle or ellipse). The combustion chamber 12 communicates with the intake port 20 via the two intake ports 21 and communicates with the exhaust port 14 via the two exhaust ports 13.

FIG. 2 is a plan view of the intake port 20 and the combustion chamber 12, and is a view of the configuration of the periphery of the combustion chamber 12 as seen from the cylinder head side in the cylinder axial direction. In the following description, as shown in FIG. 2, in the plan view of each cylinder, the direction in which the intake side and the exhaust side are aligned is defined as the L1 direction, and the direction orthogonal to the L1 direction is defined as the L2 direction. Further, in the direction orthogonal to L2, the axial direction of the cylinder (the reciprocating direction of the piston 11) is the vertical direction.

The intake port 20 is an intake passage between the connection portion with the intake manifold and the intake port 21 of the combustion chamber 12 on the downstream side. The intake port 20 is divided into two forks on the combustion chamber 12 side, and an intake port 21 is provided at each of the two ends. The air inlets 21 are provided so as to be adjacent to each other in the L2 direction.

Two exhaust ports 13 are provided so as to be adjacent to each other in the L2 direction, similarly to the intake port 21. The center positions of the two exhaust ports 13 in the L2 direction are provided on a center line CL that passes through the center position of the intake port 21 in the L2 direction and extends in the L1 direction. Note that the number of exhaust ports may be one instead of two. In that case, one exhaust port may be provided on the center line CL.

Referring to FIG. 1, the description of the engine control system will be continued. A spark plug 16 is provided at the center of the ceiling (cylinder head) of the combustion chamber 12. The center part of the ceiling part where the spark plug 16 is provided may be within a predetermined range including the center point of the ceiling part. Specifically, the spark plug 16 is a line connecting the center position on the intake side of the combustion chamber 12 (center position of the two intake ports 21) and the center position on the exhaust side (center position of the two exhaust ports 13), That is, it is provided at a position on the center line CL (see FIG. 2). In addition, the spark plug 16 should just be provided in the center part of the ceiling part, More preferably, it is good to be provided on the centerline CL of the center part. A high voltage is applied to the ignition plug 16 at a desired ignition timing through an ignition device 17 including an ignition coil. By applying a high voltage to the spark plug 16, an arc discharge A is generated between the counter electrodes 16a (see FIG. 5), and the fuel in the combustion chamber 12 is ignited by the energy of the arc discharge A.

A fuel injection valve 18 that directly supplies fuel into the combustion chamber 12 is provided at the upper portion of each cylinder of the engine 10 and on the intake port 20 side. The fuel injection valve 18 is provided on the center line CL shown in FIG. The fuel injection valve 18 is connected to a fuel tank via a fuel pipe (not shown). The fuel in the fuel tank is supplied to the fuel injection valve 18 of each cylinder and injected from the fuel injection valve 18 into the combustion chamber 12.

The intake port 20 and the exhaust port 14 of the engine 10 are respectively provided with an intake valve 22 that closes the intake port 21 and an exhaust valve 15 that closes the exhaust port 13. The air in the intake port 20 flows into the combustion chamber 12 by the opening operation of the intake valve 22, and the exhaust gas in the combustion chamber 12 is discharged to the exhaust port 14 by the opening operation of the exhaust valve 15. The opening / closing timing (valve timing) of the intake valve 22 and the exhaust valve 15 is variably controlled by the variable valve timing device 23.

In addition, the intake port 20 is provided with a rotary valve 50 for adjusting the airflow generated in the combustion chamber 12. In the rotary valve 50, the opening degree of the valve body 53 is adjusted by the rotary actuator 51. The rotary actuator 51 incorporates a sensor for detecting the opening degree of the rotary valve 50. The rotary valve 50 corresponds to an “air flow adjusting unit”, “flow path varying device”, and “open / close valve”.

The intake port 20 is connected to an intake pipe 31 including an intake manifold and a surge tank. The intake pipe 31 is provided with a throttle valve 33 whose opening degree is adjusted by a throttle actuator 32 such as a DC motor. The throttle actuator 32 incorporates a throttle opening sensor for detecting the throttle opening. Instead of adjusting the flow rate flowing from the intake pipe 31 by the throttle valve 33, an independent throttle may be provided for each cylinder. The rotary valve 50 may also function as an independent throttle provided in each cylinder.

An exhaust pipe 34 is connected to the exhaust port 14. A turbocharger 35 is provided that compresses the gas in the intake pipe 31 using the exhaust from the exhaust pipe 34. The turbocharger 35 includes an intake air compressor 36 disposed on the upstream side of the throttle valve 33 in the intake pipe 31 and an exhaust turbine 37 disposed on the upstream side of the three-way catalyst 39 that is an exhaust purification catalyst in the exhaust pipe 34. And. The intake compressor 36 and the exhaust turbine 37 are connected by a rotating shaft 38. When the exhaust turbine 37 is rotated by the exhaust gas flowing in the exhaust pipe 34, the intake compressor 36 is rotated along with the rotation. At this time, the intake air is compressed into the intake pipe 31 by the centrifugal force generated by the rotation of the intake compressor 36. The turbocharger 35 may not be used. An air-fuel ratio sensor 40 is provided between the exhaust turbine 37 and the three-way catalyst 39.

The intake pipe 31 is provided with an intercooler 41 on the downstream side of the intake compressor 36. The gas compressed (supercharged) by the turbocharger 35 (intake compressor 36) is cooled by the intercooler 41 and sent to the downstream side. By cooling the gas supercharged by the intercooler 41, the gas charging efficiency can be increased. The intake pipe 31 is provided with an air cleaner 42 and an air flow meter 43 for detecting the intake air amount upstream of the intake compressor 36.

An EGR pipe 44 is provided so as to connect the downstream side of the three-way catalyst 39 of the exhaust pipe 34 and the downstream side of the air flow meter 43 of the intake pipe 31. A part of the exhaust gas in the exhaust pipe 34 can be introduced into the intake air by the EGR pipe 44, and a system called LPL-EGR (Low Pressure Loop Exhaust Gas Recirculation) is configured. The EGR pipe 44 is provided with an EGR cooler 45 that cools the exhaust gas in the EGR pipe 44 and an EGR control valve 46. The EGR control valve 46 is provided so as to be able to control the EGR rate (exhaust gas mixing ratio in the pre-combustion gas sucked into the combustion chamber 12) by the opening degree. The EGR system may be HPL-EGR instead of LPL-EGR, or may not use the EGR system. Further, either the EGR cooler 45 or the EGR control valve 46 may be upstream and which may be downstream.

The engine 10 includes a crank angle sensor 47 that outputs a rectangular crank angle signal for each predetermined crank (for example, 30 ° CA cycle) as the engine 10 rotates, and a knock sensor that detects occurrence of knock in the engine 10. 48 is provided. Based on the detection of the crank angle sensor 47, the rotational speed NE of the engine 10 is calculated. An accelerator opening sensor 49 is provided for detecting the amount of accelerator depression by the driver (accelerator opening).

The engine control system includes an ECU 60. As is well known, the ECU 60 is mainly composed of a microcomputer including a CPU, a ROM, a RAM, and the like. The ECU 60 calculates the operating status of the engine 10 based on outputs from various sensors such as the crank angle sensor 47. And according to the driving | running state of the engine 10, the signal for controlling various apparatuses, such as the ignition device 17, is output. The ECU 60 corresponds to a “control device”.

Next, the turbulence of the airflow when the airflow is not adjusted by the rotary valve 50 will be described with reference to FIGS. FIG. 3 is a schematic plan sectional view showing the combustion chamber 12 as viewed from the piston 11 side in the axial direction of the cylinder and showing the air flow in the combustion chamber 12. In FIG. 3, the intake port 21 and the spark plug 16 are indicated by broken lines, and the airflow is indicated by arrows. FIG. 4 is an enlarged view of the vicinity of the spark plug 16 (counter electrode 16a), and shows the airflow at the position of the spark plug 16.

The straight-ahead distance from the intake port 21 to the inner peripheral surface of the combustion chamber 12 is shorter than the distance from the intake port 21 toward the center position of the combustion chamber 12. Therefore, the airflow reaches the inner peripheral surface before the central position at the straight position from the air inlet 21. Then, the airflow that has arrived heads toward the center along the shape of the inner peripheral surface, and the airflows coming from both directions in the L2 direction collide with each other at the center position and return to the direction of the intake port 21. As a result, as shown in FIG. 3, at the center position, the air flow from the intake port 21 side to the exhaust port 13 side collides with the air flow returned to the inner peripheral surface.

When airflows collide at the central position, turbulent flow is generated in the vicinity of the spark plug 16 as shown in FIG. When the turbulent flow occurs, the arc discharge A generated between the counter electrodes 16a of the spark plug 16 does not become a regular arc shape as shown by a two-dot chain line, but is distorted as a solid line. As a result of the arc discharge A being distorted, the distance between the arc discharges A is partially shortened, short-circuited there, and the discharge distance of the arc discharge A is shortened as shown by the broken line. As a result, it becomes difficult to secure a discharge distance necessary for the ignition of the arc discharge A, and the ignition of the fuel is hindered.

Therefore, in the present embodiment, in the air flow from the intake side to the exhaust side, the air flow at the position (center position) of the spark plug 16 generates a biased current that is strengthened compared to the air flow at other positions. doing. A rotary valve 50 as an example of the configuration for that purpose will be described with reference to FIGS. 2 and 5 to 7. 5 is a perspective view of the rotary valve 50, FIG. 6 is a cross-sectional view of the intake port 20 at a position where the rotary valve 50 is provided, and FIG. It is a figure which shows an airflow. The arrows in FIG. 7 indicate the airflow, the thickness of the arrow indicates the strength of the airflow, and the thick arrow indicates a state where the airflow is stronger than the thin arrow.

The flow path cross section of the intake port 20 before bifurcating the rotary valve 50 has a rounded rectangular shape or an oval shape with a long L2 direction. The rotary valve 50 is provided at a position before the intake port 20 branches into two forks. Further, at the position where the rotary valve 50 is provided, a part of the intake port 20 is enlarged in the vertical direction of the cylinder so that the rotary valve 50 can rotate.

The rotary valve 50 includes a shaft body 52 disposed in a direction extending in the L2 direction, and a valve body 53 supported by the shaft body 52, and the valve body 53 is pivoted about the shaft body 52. The opening degree is adjusted by. The valve body 53 has a notch 54 that extends in the direction perpendicular to the L1 direction (the circumferential direction of the valve body 53) at the center in the L2 direction, and depends on the rotational position of the valve body 53 in the intake port 20. The in-port flow path is locally closed, limiting the air passage range within the intake port 20.

The position of the valve body 53 in the intake port 20 will be specifically described with reference to FIG. In the state shown in FIG. 7A, all or substantially all of the valve body 53 is located outside the intake port 20, and the in-port flow path is in a fully open state. In contrast, in the state shown in FIGS. 7B and 7C, the valve body 53 is moved into the intake port 20, and the in-port flow path is partially closed by the valve body 53. That is, the rotary valve 50 is in a partially open state by allowing the airflow to pass through the notch 54. In this state, the air flow rate in the central portion in the L2 direction in the in-port flow path is greater than that on both sides. In the state of FIG. 7B, the degree of drift of the airflow flowing into the cylinder is small, whereas in the state of FIG. 7C, the degree of drift of the airflow flowing into the cylinder is large. The degree of drift indicates the intensity of drift (the magnitude of the bias).

In this way, the flow of the air flow in the combustion chamber 12 in the case where the tumble flow is generated by increasing the degree of drift is described. FIG. 8 is a diagram of the combustion chamber 12 as viewed from the piston 11 side in the cylinder axial direction, and is a schematic cross-sectional view showing the air flow in the combustion chamber 12. In FIG. 8, the intake port 21 and the spark plug 16 are indicated by broken lines, and the airflow is indicated by arrows.

The opening degree of the rotary valve 50 is adjusted so that the degree of drift is strong, that is, only the center position is open. That is, while the outside is not open and the outside airflow is weak, the airflow at the center position is strengthened, so that the airflow at the center side is relatively biased. In this state, when the two intake ports 21 are opened, a strong airflow flows near the center of the intake port 20, and the airflow hits the valve head of the intake valve 22 so as to be further closer to the center side. Flows in. Then, in the combustion chamber 12, the airflow on the central side, which is the side close to each other in the two intake ports 21, is strengthened compared to the airflow on the outside thereof, thereby generating a drift.

And, the airflow that flows from the intake port 21 with a biased current has a relatively strong and faster speed of the airflow that travels straight through the central position than the other positions. Therefore, the airflow that travels through the central position reaches the inner peripheral surface of the combustion chamber 12 before the airflow at other positions. And the airflow which reached | attained goes outside along the shape of an internal peripheral surface. As a result, at the central position, the airflow flowing from the air inlet 21 and the airflow returning to the inner peripheral surface do not collide, and the occurrence of turbulence is suppressed. Further, even if a small turbulent flow is generated by hitting the spark plug 16 or the like, the airflow at the center position is strong, so the turbulent flow is extinguished by the strong flow. Therefore, the airflow at the position of the spark plug 16 is stabilized, the short circuit of the arc discharge A can be suppressed, and the ignitability can be ensured.

Next, the case where such drift is performed will be described with reference to FIGS. FIG. 9 is a flowchart executed by the ECU 60, and this process is executed by the ECU 60 at a predetermined cycle. FIG. 10 is a diagram showing the engine rotation speed, the load, and the degree of drift.

In FIG. 9, in step S11, it is determined whether or not the engine 10 is in a starting state. For example, after the start of cranking associated with the start request of the engine 10, if the engine 10 is in a period from when the engine 10 starts to burn until the rotational speed NE of the engine 10 rises to a predetermined complete explosion speed, the start state It is determined that it is. It may be determined that the predetermined time elapses after the rotational speed NE of the engine 10 has increased to the complete explosion rotational speed. If it is determined that the engine is in the starting state, the process proceeds to step S14. If it is determined that the engine is not in the starting state, the process proceeds to step S12.

In step S12, based on the detected value of the accelerator opening sensor 49 and the rotational speed NE of the engine 10, it is determined whether or not the engine is in an idle state. If it is determined that the accelerator opening is 0, the rotational speed NE is within the predetermined range, and the engine is in the idle state, the process proceeds to step S14. On the other hand, if it is not determined that the vehicle is in the idle state, the process proceeds to step S13.

In step S13, it is determined whether or not the three-way catalyst 39 is warmed up early. Specifically, when the temperature of the three-way catalyst 39 estimated by a known method is lower than the activation temperature, it is determined that the three-way catalyst 39 is in a state of being warmed up early. When step S13 is affirmed (when the temperature of the three-way catalyst 39 is lower than the activation temperature), the process proceeds to step S14, and when negative, the process proceeds to step S15. Note that a sensor that detects the temperature of the three-way catalyst 39 may be provided, and the determination may be performed based on the detected temperature.

In step S14, drift control is executed. When the operating condition of the engine 10 is an idle state, a starting state, or a state in which the three-way catalyst 39 is warmed up early, the opening of the rotary valve 50 is in a state where only the central portion is opened (FIG. 7C). In this state, the rotary actuator 51 is driven so as to execute the drift control, and the process is terminated.

In step S15, it is determined whether the fuel ratio in the gas in the combustion chamber 12 is low. Specifically, it is determined whether the combustion chamber 12 is in a lean state or a state in which the EGR rate is higher than a predetermined value during combustion. If the operating condition of the engine 10 is a low fuel ratio, the process proceeds to step S17. If the fuel ratio is not low, the process proceeds to step S16.

In step S16, it is determined whether or not the operating condition is likely to cause knock. Specifically, it is determined that there is a possibility that knocking may occur when the temperature in the combustion chamber 12 is high or when the compression ratio is high due to supercharging of the turbocharger 35. If it is determined in step S16 that the driving condition is likely to cause knock, the process proceeds to step S17. If it is determined that the driving condition is not likely to cause knock, the process is terminated.

In step S17, the rotational speed NE of the engine 10 is acquired. Specifically, based on the crank angle signal detected by the crank angle sensor 47, the rotational speed NE of the engine 10 is calculated and obtained.

In step S18, the engine load is acquired. Specifically, the engine load is calculated based on the accelerator opening detected by the accelerator opening sensor 49, and obtained.

In step S19, it is determined whether the rotational speed NE and engine load acquired in step S17 and step S18 correspond to the non-operating region. Specifically, as shown in FIG. 10, when the rotational speed NE of the engine 10 is smaller than a predetermined value or when the engine load is smaller than a predetermined value, it is determined that the non-operating region is met. In this region, the drift control is not performed in order to suppress the power consumption due to the drift operation. If it is determined in step S19 that the region does not correspond to the non-operating region, the process is terminated. If it is determined that the region does not correspond to the non-operating region, the process proceeds to step S20.

In step S20, it is determined whether the rotational speed NE and engine load acquired in step S17 and step S18 correspond to the priority area. Specifically, as shown in FIG. 10, when the rotational speed NE of the engine 10 is larger than a predetermined value or when the engine load is larger than a predetermined value, it is determined to fall within the priority area. In this region, drift control is not performed in order to give priority to output. If it is determined in step S20 that it corresponds to the priority area, the process is terminated, and if it is determined that it does not correspond to the priority area, the process proceeds to step S21.

In step S21, the degree of drift is set based on the rotational speed NE and engine load acquired in step S17 and step S18. Specifically, as shown in FIG. 10, the greater the rotational speed NE of the engine 10, the greater the degree of drift. As the rotational speed NE of the engine 10 is higher, the in-cylinder flow velocity is higher and turbulence is more likely to occur. In such a case, the degree of drift is increased. Further, the smaller the engine load, the greater the degree of drift. When the load is low, the amount of air in the cylinder decreases. In this case, the necessary air flow rate can be ensured by increasing the degree of drift.

In step S22, drift control is executed based on the drift degree set in step S21. By driving the rotary actuator 51 so that the opening degree of the rotary valve 50 matches the degree of drift, the drift control is executed, and the process ends.

In addition, step S11, step S12, step S13, step S15, step S16, step S19, and step S20 correspond to a “drift determination unit”. Steps S14 and S22 correspond to a “control unit”. Step S21 corresponds to a “drift setting unit”. Steps S11 to S13 are advanced to step S14 if any one of them is satisfied, but if at least two of steps S11 to S13 are satisfied, the flow proceeds to step S14 and drift may be performed. .

Further, feedback control can be performed in addition to the control of the drift due to the operating condition, the rotational speed NE of the engine 10 and the engine load. When the drift set in FIG. 9 is performed, the combustion state of the engine 10 is confirmed, and feedback control as shown in FIG. 11 is performed based on the confirmation. FIG. 11 is a flowchart for feedback control, and this process is performed by the ECU 60 at a predetermined cycle. The control according to this flowchart corresponds to “feedback control by the control unit”.

In step S51, it is determined whether or not drifting is being executed. If the drift is not executed, the process is terminated. On the other hand, if the drift is being executed, it is detected in step S52 whether an ignition abnormality has occurred in the combustion of the engine 10. Specifically, when misfire or the like due to an abnormal ignition occurs, an abnormality occurs in the rotational speed NE of the engine 10 detected by the crank angle sensor 47, and therefore an abnormal ignition occurs based on the value detected by the crank angle sensor 47. It is determined whether or not. If it is determined that an ignition abnormality has occurred, the process proceeds to step S54. Note that step S52 corresponds to a “parameter acquisition unit”, and the rotational speed NE of the engine 10 corresponds to a “parameter”. In step S52, the detection result of the air-fuel ratio sensor 40 may be used to determine that the ignition abnormality has occurred when there is unburned fuel, that is, when combustion failure has occurred.

If it is determined in step S52 that no ignition abnormality has occurred, it is determined in step S53 whether knock has occurred. Specifically, it is determined whether or not the knock sensor 48 detects the occurrence of the knock. If the occurrence of knocking is detected, the process proceeds to step S54. On the other hand, if the occurrence of knocking is not detected, the process is terminated.

In step S54, the drift degree is changed so as to increase the drift degree. In step S55, the drift control is executed based on the drift degree set in step S54. By driving the rotary actuator 51 so that the opening degree of the rotary valve 50 matches the degree of drift, the drift control is executed, and the process ends.

Next, as described above, the effect of performing the drift will be described with reference to FIGS. 12 is a diagram showing the relationship between the in-cylinder flow and the arc maintenance time, FIG. 13 is a diagram showing the relationship between the arc maintenance time and the ignition timing, and FIG. 14 shows the relationship between the in-cylinder flow and the main combustion period. FIG. 15 is a diagram showing the relationship between the ignition timing and the main combustion period. In FIG. 12 to FIG. 15, the arc maintenance time is a time during which the arc discharge A can be maintained at a desired discharge distance. Further, the conventional variation between combustion cycles is a variation between combustion cycles when drift is not performed, and is indicated by a broken line.

As shown in FIG. 12, when the in-cylinder flow is weak, turbulent flow is unlikely to occur in the vicinity of the spark plug 16, so the arc maintenance time is long and the variation in arc maintenance time between combustion cycles is small. On the other hand, if the in-cylinder flow is strengthened without applying a drift as in the prior art, turbulent flow in the vicinity of the spark plug 16 occurs. For this reason, the arc maintenance time tends to be short, and the variation in arc maintenance time between combustion cycles becomes large. Therefore, when drifting is performed as in the present embodiment, generation of turbulent flow in the vicinity of the spark plug 16 is suppressed. Therefore, as in the case where the in-cylinder flow is weak, even when the in-cylinder flow is strong, the arc maintenance time is long and the variation in the arc maintenance time between combustion cycles is small. As a result, it is possible to achieve both stable ignition and combustion promotion by strengthening in-cylinder flow.

When the in-cylinder flow is strengthened in the state where no drift is performed as in the conventional case, the arc maintenance time is shortened. As shown in FIG. 13, when the arc maintenance time is short, the time (ignition timing) required to ignite the fuel from the arc discharge A increases. On the other hand, when the arc maintenance time is long as in the present embodiment, the time taken to ignite the fuel from the arc discharge A is shortened and the variation is reduced. Therefore, it can contribute to the stability of ignition.

Also, conventionally, in-cylinder flow is weakened to ensure arc maintenance time. In this case, as shown in FIG. 14, the main combustion period becomes longer or the variation becomes larger. On the other hand, when the drift is performed and the in-cylinder flow is strengthened as in the present embodiment, the combustion is promoted, so that the main combustion time is shortened and variations in the time required for the main combustion can be suppressed.

Further, as shown in FIG. 15, conventionally, the ignition timing is delayed, and the main combustion period has a large variation. On the other hand, when drifting is performed and the in-cylinder flow is strengthened as in the present embodiment, the time required for ignition is shortened (ignition timing is advanced), and the combustion is promoted by stable ignition and strong in-cylinder flow. The time required for main combustion is shortened.

As described above, since the ignition is stable and the time required for the main combustion can be shortened, an effect under various operating conditions is produced. For example, even if the driving condition may cause knocking, knocking is less likely to occur even if the ignition timing is advanced. Therefore, it is possible to improve fuel efficiency under driving conditions where knocking may occur. Further, even when the lean combustion or the EGR rate is high, the combustion can be improved. Therefore, the lean limit and the limit EGR rate can be increased, and fuel consumption can be improved. Even in the start state and the idle state, the time required for the main combustion is small and the combustion is stabilized, so that the generation of unburned HC can be suppressed. Furthermore, even in a state where the three-way catalyst 39 is warmed up early, the ignition timing can be retarded as compared with the prior art by stabilizing the ignition. Therefore, the temperature of the exhaust can be raised, and the activity of the three-way catalyst 39 can be accelerated.

According to the embodiment described above in detail, the following excellent effects can be obtained.

In the airflow from the intake side to the exhaust side, it is determined whether or not the airflow at the position of the spark plug 16 causes a stronger drift than the airflow at other positions. And when it determines with producing a drift, the rotary valve 50 is controlled so that a drift may be produced. In this way, by generating a drift in which the airflow at the position of the ignition plug 16 in the combustion chamber 12 is strengthened, the airflow at the position of the ignition plug 16 first hits the inner peripheral wall of the combustion chamber 12 and follows its shape. Since it goes to the outside, the occurrence of turbulent flow at the position of the spark plug 16 is suppressed. Therefore, even in a situation where the ignitability tends to become unstable, the airflow in the vicinity of the spark plug 16 is stabilized, the short circuit of the arc discharge A can be suppressed, and the ignitability can be ensured. That is, the ignitability can be ensured while ensuring the airflow necessary for fuel promotion.

It can be made to drift when necessary based on the operating conditions of the internal combustion engine. For example, when the combustion chamber 12 is in a lean state during combustion or when the EGR rate is high, that is, when the fuel ratio in the gas in the combustion chamber 12 is low, ignition from the arc discharge A of the spark plug 16 to the fuel is performed. The conditions that can be done are becoming stricter. In addition, a strong airflow is required to promote combustion. In such a case, by ensuring the ignitability by drifting while ensuring the airflow necessary for fuel promotion, the ignitability can be ensured even at a low fuel ratio, and the fuel efficiency can be improved.

Further, when there is a possibility that knocking may occur in the combustion chamber 12, in general, it is suppressed by retarding the ignition timing. In order to suppress the occurrence of knocking, there is a method in which the flow in the cylinder is strengthened and the combustion is spread quickly. However, if the flow in the cylinder is strengthened, the ignition timing can be advanced, while turbulent flow is generated and ignition is difficult. Therefore, in the present embodiment, the ignition timing can be advanced even if there is a possibility that knocking may occur by strengthening the flow in the cylinder and drifting to ensure ignitability.

As the rotational speed NE of the engine 10 increases, the flow velocity of the airflow in the combustion chamber 12 increases, and turbulence is likely to occur near the spark plug 16. Therefore, turbulent flow can be suppressed by increasing the strength of drift as the rotational speed NE is higher.

When the engine load is low, turbulent flow is likely to occur because the air passage range is small and the flow velocity is large. Therefore, the turbulent flow can be suppressed by increasing the strength of the drift as the load is lower.

When at least one of the case where the load is lower than the predetermined amount and the amount of gas flowing from the intake port 20 is small and the rotational speed NE of the engine 10 is lower than the predetermined amount, the consumption due to the drift operation is not caused by causing no drift. Electric power can be suppressed.

In at least one of the case where the load is higher than the predetermined amount and the amount of gas flowing in from the intake port 20 is large and the rotational speed NE of the engine 10 is higher than the predetermined value, the output of the internal combustion engine is suppressed by suppressing the drift. Can be prioritized.

When the engine 10 is in an idling state, a starting state, or a state in which the three-way catalyst 39 is warmed up early, combustion is likely to become unstable due to a small amount of air or a delayed ignition timing. In such a case, the ignitability can be improved by causing the engine 10 to drift even when the engine 10 is in an idle state, a starting state, or a state in which the three-way catalyst 39 is warmed up early.

フィードバック By performing feedback control, when the ignition condition of the spark plug 16 is poor, the ignitability can be improved by drifting.

By providing the rotary valve 50 that drifts while restricting the air passage range in the intake port 20, it is not necessary to provide a structure for drifting in the combustion chamber 12, and the combustion chamber 12 can be easily designed.

In the intake port 20, the turbulence of the air flow in the combustion chamber 12 is suitably suppressed by opening the central portion of the center portion and both side portions in a plan view of the cylinder more than the both side portions to be in a partially open state. it can. In this case, airflow reinforcement can be implemented while suppressing the generation of turbulent airflow in the vicinity of the spark plug 16.

Second Embodiment
In the second embodiment, a configuration for suppressing turbulent flow in the intake port will be described with reference to FIGS. 16 to 18. FIG. 16 is a perspective view of the rotary valve 50, and FIG. 17 is a cross-sectional view of the flow path showing a state where the intake port 20 is opened and closed by the rotary valve 50. In FIG. 17, hatched portions indicate regions where the valve body 53 closes the intake port 20. FIG. 18 shows the intake port 20 in a state in which the intake port 20 is partially open and a circulating air flow F2 is formed in the intake port 20 when the intake port 20 is viewed in a cylinder plan view (schematic closed sectional view of the intake port 20). It is a figure which shows the flow of an airflow. In FIG. 18, an arrow indicates an air flow, the thickness of the arrow indicates the speed of the air flow, and the thick arrow indicates a state where the air flow is faster than the thin arrow.

In the conventional tumble control valve, the airflow in the intake port is mainly restricted in the vertical direction. Therefore, even if a quick air flow is created by the tumble control valve, the air currents collide with each other in the intake port or collide with the wall of the intake port, turbulence occurs in the intake port, and the fast air flow is attenuated. It was spreading. In order to solve such a problem, for example, a partition wall reaching the vicinity of the intake port is provided in the intake port of Japanese Patent No. 4349156. However, if the partition wall is provided to the vicinity of the intake port, the partition wall is provided in the cylinder head, particularly to the passage after bifurcating, and the cylinder head needs to be modified. Therefore, the mountability is deteriorated.

Therefore, in the first embodiment, the notch 54 is provided in the center of the rotary valve 50 to increase the drift of the central portion, thereby suppressing the turbulence of the air flow in the combustion chamber 12. In the second embodiment, the rotary valve 50 is further improved in order to suppress turbulent flow in the intake port 20.

A rotary valve 50 according to the second embodiment will be described with reference to FIGS. 16 and 17. The rotary valve 50 includes a shaft body 52 disposed in a direction extending in the L2 direction, and a valve body 53 supported by the shaft body 52, and the valve body 53 is pivoted about the shaft body 52. The opening degree is adjusted by.

The valve element 53 has a size corresponding to the entire area in the L2 direction, and reaches the port wall surface 24 in the L2 direction. The valve body 53 has a shape obtained by cutting off a part of the circumferential surface of the cylinder. The valve body 53a has a width dimension and a circumferential dimension that allow the intake port 20 to be fully closed, and a notch. And a shielding part 53 b provided on the side of the part 54.

The valve body 53 is provided with a notch 54 extending in the circumferential direction of the valve body 53 at the center in the L2 direction. The cutout portion 54 has a semicircular portion 54a having a semicircular shape at one end, and an equal width portion 54b extending to be equal to the semicircular portion 54a so as to be continuous with the semicircular portion 54a. The end portion of the valve body 53 from 54b is a widened portion 54c in which the equal width portion 54b widens to the dimension of the valve body 53 in the L2 direction. As shown in FIG. 17C, the equal width portion 54b has a dimension in the circumferential direction that opens the entire length in the vertical direction (direction intersecting the direction in which the intake ports 21 are arranged) in a partially open state.

The ratio of the dimension in the L2 direction of the notch 54 and the dimension in the L2 direction of the shielding part 53b (the width dimension from the port wall surface 24 to the notch 54), that is, the ratio of a: b in FIG. The desired circulation air flow F2 is formed in the intake port 20 while securing a necessary flow rate from 54. For example, the ratio of a: b is 0.85: 1 or less. The dimension of the notch 54 in the L2 direction is, for example, one third or less of the dimension of the intake port 20 in the L2 direction.

The position of the valve body in the intake port 20 will be specifically described with reference to FIG. In the state shown in FIG. 17A, all or substantially all of the valve body 53 is located outside the intake port 20, and the in-port flow path is in a fully open state. On the other hand, in the state shown in FIGS. 17B to 17E, the valve body 53 is moved into the intake port 20, and the in-port flow path is partially closed by the valve body 53. In particular, in the states shown in FIGS. 17C to 17E, a partially open state in which a circulating air flow F2 is formed in the intake port 20 is established. The states shown in FIGS. 17C to 17E are states in which the drift control is performed in the first embodiment, and the state of FIG. 17D has a stronger drift degree than the state of FIG. 17C. Thus, the degree of drift is stronger in the state of FIG. 17E than in FIG.

As shown in FIG. 17C, in the state where the aperture ratio (the ratio of the portion of the opening through which the airflow can pass in the flow path cross-sectional area of the intake port 20) is about 30%, the central portion is formed by the equal width portion 54b. The entire length in the vertical direction is open. On the other hand, since the shielding portion 53b extends from the notch portion 54 to the port wall surface 24, the intake passage through which the airflow can pass is narrowed toward the center side, and the airflow is accelerated at the center side.

As shown in FIG. 17E, in the state where the opening ratio is limited to about 3%, the flow path resistance due to the narrowing of the opening in the notch 54 becomes very large. Therefore, in order to reduce the flow path resistance as much as possible, the end portion of the cutout portion 54 is a semicircular semicircular portion 54a. Thereby, generation | occurrence | production of the turbulent flow by flow-path resistance when an aperture ratio (opening area) is small can be suppressed.

In the partially open state shown in FIGS. 17 (c) to 17 (e), the airflow passage F1 passing through the notch 54 is accelerated by the intake passage being throttled toward the center. The flow of the airflow in the intake port 20 when the central airflow F1 thus accelerated is formed will be described with reference to FIG.

In the partially open state, by reducing the dimension (opening width) of the notch 54 in the L2 direction, the flow velocity of the central airflow F1 that has passed through the notch 54 is also increased, and the central airflow F1 is generated in the intake port 20. It is the fastest. In the region A1 on the downstream side of the shielding part 53b, an air flow from the region A1 to the center side is generated so as to be drawn into this fast airflow. As a result, in the region A1, a negative pressure is generated in which the atmospheric pressure is lower than the surroundings. The magnitude of the relative negative pressure is determined by the speed at the position where the central airflow F1 blows out from the notch 54, and the speed of the central airflow F1 is the amount of air passing through the notch 54. And the opening area.

In this case, the airflow flowing downstream from the shielding part 53b flows backward by being drawn into the negative pressure in the region A1. As a result, an elliptical circulating air flow F <b> 2 is formed along the port wall surface 24. That is, the side area on the downstream side of the shielding portion 53b is a circulation area where the circulation airflow F2 is formed. Note that the downstream air flow F2 is determined depending on the relative magnitude of the negative pressure.

The elliptical circulation airflow F2 has a length c in the major axis direction to the branch passage 25 that branches toward each intake port 21 provided in the intake port 20, and the circulation airflow F2 is It is more desirable to have a length c in the long axis direction up to the vicinity of the intake valve 22 that closes the intake port 21. Further, since the circulating airflow F2 is formed, the airflow in the side region flows back along the port wall surface 24 and returns to the region A1, and therefore, the region A2 on the side of the intake port 21 enters the combustion chamber 12. Airflow becomes difficult to flow in. Therefore, the airflow at the side in the combustion chamber 12 becomes weaker than that at the center position. Further, by forming such a circulating air flow F2, turbulence of the air flow in the lateral regions on both sides of the notch 54 in the intake port 20 can be suppressed, and diffusion and attenuation of the central air flow F1 can be suppressed. Can be suppressed. Note that the airflow in the side region is not the entire airflow reaching the vicinity of the intake valve 22 and returning to the region A1, but the airflow returning from the middle is larger. The airflow reaching the vicinity of the intake valve 22 also flows backward toward the area A1, thereby forming a circulating airflow F2 as a whole.

However, in the lateral region, the circulating air flow F2 may be split due to a minute disturbance. If the ratio of the length d in the minor axis direction to the length c in the major axis direction of the elliptical circulating air flow F2 exceeds a predetermined ratio, there is a risk of splitting due to minute disturbance. Specifically, when the length d in the minor axis direction is smaller than one third with respect to the length c in the major axis direction of the circulating air flow F2, there is a possibility of splitting due to minute disturbance. The length d in the minor axis direction is the length from the port wall surface 24 to the central region through which the central airflow F1 flowing into each intake port 21 passes, and the length c in the major axis direction is the central airflow. This is the length from the area A1 on the side of the blowing position of F1 to the vicinity of the intake valve 22 (before the area A2).

Therefore, the length D in the L2 direction from the port wall surface 24 of the shielding portion 53b to the cutout portion 54 is set so that the length d in the minor axis direction is 1/3 or more of the length c in the major axis direction of the circulating air flow F2. A width dimension is defined. By setting the width dimension of the shielding part 53b to a predetermined size, the length d in the minor axis direction of the circulating air flow F2 is determined. Therefore, the length d in the minor axis direction is more than one third of the length c in the major axis direction based on the assumed length c in the major axis direction of the circulating airflow F2 from the shape of the intake port 20. Thus, the length d in the minor axis direction is assumed. Based on the assumed length d in the minor axis direction, the width dimension in the L2 direction from the port wall surface 24 of the shielding part 53b to the notch part 54 is determined.

As described above, in the partially opened state by the rotary valve 50 (the position of the valve body 53 is the state shown in FIGS. 17C to 17E), the intake passage is restricted to the center side by the shielding portion 53b of the valve body 53. Thus, the flow velocity of the central airflow F1 that has passed through the notch 54 is increased. By being drawn into the increased airflow, a negative pressure is generated in the region A1 in which the atmospheric pressure is lower than the surroundings. A circulating air flow F2 is formed in the lateral region so as to be drawn into this negative pressure. Moreover, since the width dimension of the shielding part 53b is determined so that the circulating air flow F2 is in a stable state, the circulating air flow F2 in the side region is stabilized without being divided. For this reason, the turbulent flow in the lateral region does not attenuate and diffuse the central airflow F1 and can generate a drift in the combustion chamber 12 with an enhanced central position.

According to the second embodiment described in detail above, the following excellent effects can be obtained in addition to the effects of the first embodiment.

The notch portion 54 has a uniform width portion 54b having a vertical dimension that opens the entire length of the intake port 20 in the vertical direction (direction intersecting the alignment direction), thereby rotating the rotary valve while increasing the drift. The opening position of 50 is only the central portion. Therefore, it is easy to maintain the fast central airflow F1 in the central portion and the circulating airflow F2 on both sides while increasing the drift. On the other hand, when the aperture ratio is extremely small, that is, when only the semicircular portion 54a that is the end portion of the notch 54 is opened, the opening shape is a semicircular shape. Therefore, the flow resistance when the air on the upstream side of the rotary valve 50 flows into the notch 54 can be reduced, and the turbulence of the air flow due to the flow resistance can be suppressed.

In the partially opened state by the rotary valve 50, the intake passage is throttled to the center side by the shielding portion 53b of the valve body 53, and the airflow is increased at the center side. By being drawn into the increased central airflow F1, a negative pressure is generated in the region A1 inside the shielding portion 53b and the port wall surface 24 on the downstream side of the shielding portion 53b.

In this case, in the region downstream of the shielding portion 53b and inside the port wall surface 24, the airflow flows backward along the port wall surface 24 toward the region A1 where the negative pressure is generated, and the circulating airflow F2 is generated. It is formed. By forming the circulating air flow F2, turbulence of the air flow in the lateral regions on both sides of the notch 54 can be suppressed, and the air flow flowing into the combustion chamber 12 becomes a desired state.

In the partially open state, the side regions on both sides of the notch 54 are vertically long along the port wall surface 24, and the length d in the short axis direction is 1/3 or more of the length c in the long axis direction. By forming the elliptical circulating airflow F2, the airflow that has passed through the notch 54 can flow into the combustion chamber 12 in a desired state while suppressing the generation of turbulent flow. In this case, the cutout portion 54 of the valve body 53 requires a size for securing a necessary amount of air. On the other hand, if the shielding part 53b becomes too small because the notch part 54 becomes large, the ratio of the length d in the minor axis direction to the length c in the major axis direction of the elliptical circulation air flow F2 is from 1: 3. May become unstable, become unstable due to minute disturbances, and split. In consideration of this point, it is desirable to adjust the width dimension from the port wall surface 24 to the cutout portion 54 of the shielding portion 53b.

The circulating air flow F <b> 2 in the lateral regions on both sides of the notch 54 has an elliptical shape because the air flow along the central high-speed air flow F <b> 1 returns to the valve body 53 side along the port wall surface 24. The width dimension from the port wall surface 24 to the notch 54 is adjusted so that the elliptical airflow reaches the branch passage 25 that branches toward the air inlet 21. For this reason, the circulating air flow F2 is stabilized and turbulence of the air flow can be suppressed.

<Third Embodiment>
In 3rd Embodiment, the structure provided with the baffle plate in 2nd Embodiment is demonstrated using FIGS. 19-22. 19 shows the intake port 20 in a cylinder plan view (schematic closed sectional view of the intake port 20), with the intake port 20 in a partially open state and a rectifying plate 55 provided, and a circulating air flow F2 in the intake port 20. It is a figure which shows the flow of the airflow of the intake port 20 in the state which formed. In FIG. 19, an arrow indicates an air current, an arrow thickness indicates the speed of the air current, and a thick arrow indicates a state where the air current is faster than a thin arrow. FIG. 20 is a channel cross-sectional view showing a state in which the intake port 20 is opened and closed by the rotary valve 50, and a rectifying plate 55 is provided on the downstream side of the valve body 53. In FIG. 20, hatched portions indicate regions where the valve body 53 closes the intake port 20. FIG. 21 is a perspective view of a state in which the rectifying plate 55 is provided integrally with the mounting plate 57. FIG. 22 is a view showing a modification of the rectifying plate 55.

19, the rotary valve 50 is attached to the cylinder head 26 and includes a body 27 having an air passage 27a and a valve body 53 provided in the air passage 27a. That is, the rotary valve 50 is an assembly of the body 27 with the air passage 27a provided therein, the valve body 53, the shaft body 52, and the like, and can be attached to the existing cylinder head 26. The intake port 20 includes a head passage 26 a provided in the cylinder head 26 and an air passage 27 a and is connected to the intake pipe 31.

When the rotary valve 50 is separated from the cylinder head 26 and assembled, the mountability is improved. On the other hand, when the distance from the intake port 21 to the valve body 53 is increased, the length c in the long axis direction of the circulating air flow F2, that is, the region A1 on the side of the blowing position of the central air flow F1 is near the intake valve 22 ( The length to the front of the area A2 is increased, and the ratio of the length c in the major axis direction to the length d in the minor axis direction of the circulating air flow F2 is set within a predetermined range while ensuring a predetermined opening by the notch 54. It becomes difficult to do. Therefore, if the width dimension of the notch 54 is ensured, the circulating air flow F2 may be split.

Therefore, a pair of rectifying plates 55 are provided in the head passage 26 a of the cylinder head 26. The rectifying plate 55 extends from the upstream side toward the downstream side in the intake port 20 toward the downstream side of the valve body 53, and in the partially opened state, the end portion of the cutout portion 54 (the cutout portion 54 of the shielding portion 53b). It arrange | positions so that it may extend downstream from a side edge part. The rectifying plates 55 are parallel to each other, and the interval between the rectifying plates 55 is substantially the same as the dimension in the width direction of the notch portion 54. If the distance between the rectifying plates 55 is the same as the width dimension of the notch portion 54, the central airflow F1 can be prevented from diffusing and damped, and the rectifying plate 55 can be fastened at a high speed from the downstream end. Will blow out. And since the center side airflow F1 blows off from the downstream edge part of the baffle plate 55, the area | region A1 of the downstream side of the baffle plate 55 becomes an area | region where a negative pressure produces. Therefore, the length c in the major axis direction of the circulating airflow F2 is shorter than that without the rectifying plate 55, and the circulating airflow F2 can be stabilized while ensuring the opening width. Note that the length of the rectifying plate 55 in the L1 direction may be set so that the ratio of the length c in the major axis direction to the length d in the minor axis direction of the circulating airflow F2 can be within a predetermined range.

Further, it is preferable to provide a clearance between the rectifying plate 55 and the valve body 53 so that the valve body 53 and the rectifying plate 55 do not slide. If the clearance between the valve body 53 and the rectifying plate 55 becomes too large, the airflow that has passed through the notch 54 may be disturbed before reaching the rectifying plate 55, but if the clearance is less than a predetermined value Even if there is clearance, there is no effect on the airflow. The rectifying plate 55 may be arranged not only in the head passage 26 a but also in the air passage 27 a to adjust the clearance between the rectifying plate 55 and the valve body 53.

As shown in FIG. 20, the rectifying plate 55 is desirably provided from one wall surface in the vertical direction of the intake port 20 to the other wall surface. The rectifying plate 55 extends from the wall surface on the side where the opening is formed (lower wall surface) to the other wall surface (upper wall surface) in the vertical direction of the intake port 20, and reaches the other wall surface. It does not have to be. That is, the vertical dimension of the rectifying plate 55 may be smaller than the vertical dimension of the flow path cross section of the intake port 20.

The rectifying plate 55 is provided with two upper and lower restricting portions 56 that restrict the airflow in the vertical direction (the direction orthogonal to the arrangement direction of the intake ports 21) in parallel with each other. The vertical restriction 56 is provided in parallel with the vertical wall surface of the intake port 20. For example, as shown in FIGS. 17E and 17D, when the area of the opening formed by the notch 54 is very small, the opening is formed in the vertical direction of the intake ports 20 (perpendicular to the arrangement direction). The airflow that has passed through the notch 54 flows along the upper and lower wall surfaces of the intake port 20. The fact that the airflow after passing through the notch 54 diffuses in the vertical direction while passing between the rectifying plates 55 contributes to a decrease in the flow velocity at the blowing position, and the relative negative pressure in the region A1. This is not desirable because of the small size. Therefore, the vertical restriction part 56 partitions the current plate 55 in the vertical direction, so that the air current can be prevented from diffusing in the vertical direction. Note that the number of the upper and lower restriction units 56 may be one, or three or more.

As shown in FIGS. 19 and 21, the rectifying plate 55 is provided integrally with the mounting plate 57. The mounting plate 57 is sandwiched between the cylinder head 26 and the body 27 and fixed, so that And 26 and the body 27. An opening 57 a having the same size as or slightly larger than the flow path cross section of the intake port 20 passes through the mounting plate 57 in the plate thickness direction. A rectifying plate 55 is provided over the hole edge in the vertical direction of the opening 57a. The mounting plate 57 is sandwiched and fixed between the cylinder head 26 and the body 27, so that the rectifying plate 55 is disposed in the head passage 26 a of the cylinder head 26. The rectifying plate 55 may be locked between the cylinder head 26 and the body 27 by other methods such as a locking claw.

The rectifying plate 55 can have other shapes as shown in FIG. For example, as shown in FIG. 22A, the rectifying plate 55 can have a blade cross-sectional shape. With such a shape, when the air passage range in the L2 direction in the intake port 20 is not limited by the valve body 53 (in the case shown in FIGS. 17A and 17B), the rectifying plate 55 has an air flow. Can be an obstacle to With the blade cross-sectional shape shown in FIG. 22A, the pressure loss of the rectifying plate 55 can be reduced.

Further, as shown in FIG. 22B, the distance between the pair of rectifying plates 55 may be narrower on the downstream side than on the upstream side. In this case, it is desirable that the rectifying plate 55 has an R shape. As described above, since the rectifying plate 55 becomes narrower from the upstream side toward the downstream side, the airflow that has passed through the notch 54 is drawn toward the center side. Further, when the circulating airflow F2 returns along the port wall surface 24, when it hits the rectifying plate 55, it proceeds along the wall surface, so that it becomes easy to join the airflow along the central airflow F1. Therefore, the stability of the circulating air flow F2 can be improved.

According to the third embodiment described in detail above, the following excellent effects can be obtained in addition to the effects of the second embodiment.

The rotary valve 50 may be provided at a position away from the intake port 21 from the viewpoint of mountability. When the rotary valve 50 is moved away from the intake port 21 in this way, the size (length c in the major axis direction) of the circulating air flow F2 from the upstream side to the downstream side increases, and the circulating air flow F2 is formed without being split. Becomes difficult. Therefore, in the partially open state, a pair of rectifying plates 55 extending from the upstream side toward the downstream side is provided at a position extending from the end portion of the notch portion 54 to the downstream side, and the downstream end portion of the rectifying plate 55 is It becomes the blowout position of the accelerated airflow. Therefore, since the upstream position of the circulating air flow F2 is also lowered to the downstream end position of the rectifying plate 55, the size of the circulating air flow F2 from the upstream side to the downstream side can be reduced, and the stability of the circulating air flow F2 can be reduced. Can be improved.

Further, for example, when the area of the opening formed by the notch 54 is very small, the opening is formed along the wall surface of the intake port 20 in the vertical direction (direction perpendicular to the arrangement direction). It is not desirable that the airflow after passing through the cutout portion 54 is diffused in the vertical direction because it causes a decrease in the flow velocity. Therefore, the rectifying plate 55 is provided with a vertical restriction 56 that restricts the airflow in the vertical direction. This vertical restriction 56 partitions the current plate 55 in the vertical direction. Therefore, it is possible to suppress the airflow from diffusing in the vertical direction.

Since the rotary valve 50 is provided outside the cylinder head 26, the distance from the rotary valve 50 to the intake port 21 is increased. Therefore, it is useful to provide a current plate 55. Further, since the rectifying plate 55 is locked between the cylinder head 26 and the body 27, the cylinder head 26 can be mounted without changing the design. Therefore, the mountability is improved.

Further, as in the modification, the rectifying plate 55 is narrowed from the upstream side toward the downstream side, so that the airflow that has passed through the notch 54 is drawn to the central region. Further, when the circulating airflow F2 returns along the port wall surface 24, the airflow strikes the rectifying plate 55 and travels along the wall surface of the rectifying plate 55, so that the airflow directed toward the inlet 21 along the central airflow F1. It becomes easy to join. Therefore, the stability of the circulating air flow F2 can be improved.

<Other embodiments>
This indication is not limited to the above-mentioned embodiment, for example, may be carried out as follows. Incidentally, the configuration of another example below may be applied individually to the configuration of the above embodiment, or may be applied in any combination.

In the first embodiment and the second embodiment, as in the third embodiment, the rotary valve 50 is assembled separately from the cylinder head 26, and the air passage in the body 27 attached to the cylinder head 26. It is desirable that the valve element 53 is arranged on the 27a. The intake port 20 is preferably composed of a head passage 26a and an air passage 27a. In each embodiment, the rotary valve 50 may be provided in the cylinder head 26.

In the third embodiment, the rectifying plate 55 is separate from the cylinder head 26 and the rotary valve 50, but may be provided in the cylinder head 26 or the like in advance. The rectifying plate 55 may be used not only when the rotary valve 50 is assembled, but also when the rotary valve 50 is provided in the cylinder head 26.

In the above embodiments, the airflow is adjusted by the rotary valve 50. However, in the first to third embodiments, a pinball type valve body may be used as shown in FIG. In the pinball type valve body, the circulating air flow F2 can be formed by adjusting the opening width. At this time, the returned circulating airflow F2 collides with the pinball type valve body and travels along the wall surface of the valve body, thereby joining the airflow toward the intake port 21 along the central airflow F1. It becomes easy.

Further, as shown in FIG. 24, the on-off valve may have another configuration in addition to the rotary valve 50 and the pinball type valve body. For example, as shown in FIG. 24 (a), a butterfly valve whose valve rotates about a shaft body may be used, or as shown in FIG. 24 (b), a shutter valve may be used. Furthermore, a louver type may be used as shown in FIG. In addition, a valve body structure in which a central portion such as a hinge valve, a shutter valve, a poppet valve, a disk valve, or the like has a strong airflow may be used. In the second embodiment and the third embodiment, it is desirable that the shielding portions 53b be provided on both sides of the L2 direction cutout portion 54.

As the air flow adjusting unit, instead of using the rotary valve 50 provided in the intake port 20, a compressed air introducing device 58 may be used as shown in FIG. Specifically, as shown in FIG. 25A, a compressed air introduction device 58 is provided on the cylinder peripheral wall portion, and the compressed air is introduced into the cylinder from the introduction device 58, so that a desired in-cylinder airflow is generated. It should be generated. Alternatively, as shown in FIG. 25B, a compressed air introduction device 58 is provided in the intake port 20, and the compressed air is introduced into the intake port 20 from the introduction device 58, thereby generating a desired in-cylinder airflow. You may make it make it.

Although the present disclosure has been described based on the embodiments, it is understood that the present disclosure is not limited to the embodiments and structures. The present disclosure includes various modifications and modifications within the equivalent range. In addition, various combinations and forms, as well as other combinations and forms including only one element, more or less, are within the scope and spirit of the present disclosure.

Claims

Combustion in which the inner peripheral surface is circular and communicates with the intake port (20) via the two intake ports (21) and also communicates with the exhaust port (14) via the exhaust port (13). Room (12),
A spark plug (16) provided at the center of the ceiling covering the combustion chamber;
A control device (60) applied to an internal combustion engine (10) comprising an airflow adjusting section (50) for adjusting an airflow generated in the combustion chamber,
A drift determination unit that determines that the airflow at the position of the spark plug is strengthened compared to the airflow at other positions to cause a drift;
A control device for an internal combustion engine, comprising: a controller that causes the airflow adjusting unit to cause the drift when the drift determining unit determines that drift is to be performed.
2. The control apparatus for an internal combustion engine according to claim 1, wherein the drift determination unit determines that the drift occurs when the combustion chamber is in a lean state during combustion or when an EGR rate is higher than a predetermined value.
The control apparatus for an internal combustion engine according to claim 1 or 2, wherein the drift determination unit determines that the drift is caused when there is a risk of knocking in the internal combustion engine.
A drift setting unit for setting the strength of the drift,
The said drift setting part strengthens the intensity | strength of the said drift, so that the rotational speed of the said internal combustion engine is high, or the said internal combustion engine becomes a low load. Control device for internal combustion engine.
2. The drift determination unit determines that the drift does not occur in at least one of a case where a load of the internal combustion engine is lower than a predetermined value and a case where a rotation speed of the internal combustion engine is lower than a predetermined value. The control device for an internal combustion engine according to claim 4.
The drift determination unit determines that the drift does not occur in at least one of a case where a load of the internal combustion engine is higher than a predetermined value and a case where a rotation speed of the internal combustion engine is higher than a predetermined value. The control device for an internal combustion engine according to claim 5.
4. The method according to claim 1, wherein the drift determination unit determines that the drift occurs when the internal combustion engine is in a start state, an idle state, or a state in which the exhaust purification catalyst is warmed up early. The control apparatus for an internal combustion engine according to the item.
In a situation where the drift is caused by the air flow adjustment unit, a parameter acquisition unit that acquires a parameter indicating an ignition state in the combustion chamber,
The control device for an internal combustion engine according to any one of claims 1 to 7, wherein the control unit feedback-controls the state of the drift based on the parameter.
The airflow adjustment unit is a flow path variable device that restricts an air passage range in the intake port to cause the drift.
The control of the internal combustion engine according to any one of claims 1 to 8, wherein the control unit generates the drift by restricting an air passage range in the intake port by the flow passage variable device. apparatus.
An intake system comprising: the control device for an internal combustion engine according to any one of claims 1 to 9; and the airflow adjustment unit,
The air flow adjusting portion is partially opened by opening the central portion of the intake port between the central portion that is the center in the cylinder plan view of the internal combustion engine and the both side portions that are both sides thereof, than the both side portions. An on-off valve that makes it possible to
The said control part is an intake system which produces the said drift by making the said on-off valve into the said partial open state.
The intake system according to claim 10, wherein the on-off valve is provided upstream of a position where the intake port branches to the two intake ports.
The on-off valve comprises a valve body (53) having a size corresponding to the entire region in the alignment direction of the central portion and the both side portions,
In the valve body, a cutout portion (54) extending in a direction orthogonal to the arrangement direction is formed at a portion to be the central portion,
The intake system according to claim 11, wherein the partially opened state is obtained by allowing the airflow to pass through the notch.
The valve body has a shielding portion (53b) that extends to the port wall surface (24) in the direction in which the two intake ports are arranged at the portions that are the both side portions,
In the partially open state, the airflow is made to flow backward from the inlet side along the port wall surface in the side region that is downstream of the shielding portion and along the port wall surface to form a circulating airflow (F2). The intake system according to claim 12, wherein the intake system is a circulating region.
In the intake port, on the downstream side of the shielding portion, the port is vertically long along the wall surface of the port, and the length (d) in the minor axis direction is 1/3 or more of the length (c) in the major axis direction. The intake system according to claim 13, wherein a width dimension from the port wall surface to the notch is determined so that the elliptical circulating airflow is formed.
The intake port is provided with a branch passage (25) that branches toward each of the intake ports,
A width dimension from the wall surface of the port to the notch is defined in the shielding portion so that the elliptical circulation airflow having a length in the major axis direction from at least the shielding portion to the branch passage is formed. The intake system of claim 13.
In the intake port, a pair of rectifying plates are arranged so as to extend from the upstream side toward the downstream side of the valve body and to extend downstream from the end of the notch in the partially open state. The intake system according to any one of claims 12 to 15, wherein (55) is provided.
The air flow adjusting unit includes a body (27) attached to a cylinder head (26) of the internal combustion engine and having an air passage (27a), and the valve body supported by the body,
The intake port includes the air passage and a head passage (26a) provided in the cylinder head.
The intake system according to claim 16, wherein the rectifying plate is provided in the head passage in a state of being locked to the cylinder head.
The intake system according to claim 16 or claim 17, wherein the distance between the pair of rectifying plates is narrower on the downstream side than on the upstream side.
The intake system according to any one of claims 16 to 18, wherein the rectifying plate is provided with a vertical restriction (56) for restricting an air flow in a direction orthogonal to the direction in which the intake ports are arranged.
The notch includes a semicircular part (54a) having a semicircular shape at one end thereof, and a constant width part (54b) extending in a direction intersecting the arrangement direction and having the same width as the diameter of the semicircular part. And
20. The intake air according to claim 12, wherein the equal-width portion has a dimension that opens a full length in a direction intersecting the alignment direction in the intake port in the partially opened state. system.
The air flow adjusting unit is a compressed air introduction device (58) for introducing compressed air into the intake port or the combustion chamber so as to cause the drift in the combustion chamber.
The control device for an internal combustion engine according to any one of claims 1 to 8, wherein the control unit causes the drift by causing the compressed air introduction device to introduce compressed air.