JP2011226335A - Exhaust reflux device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology for increasing an EGR ratio and preventing combustion deterioration in an exhaust reflux device for an internal combustion engine that stratifies EGR gas and air in a combustion chamber.SOLUTION: The exhaustion reflux device for an internal combustion engine 1 is equipped with an EGR device 17 that returns part of exhaust from the internal-combustion engine to an intake system as EGR gas. The internal combustion engine comprises two intake ports 3A and 3B that form a tumble flow in the same direction within a cylinder 2. The two intake ports are arranged along the same virtual plane parallel to a cylinder central axis C, in parallel in a vertical direction. Two openings 5A and 5B are arranged at the upper part of the cylinder and connected to the two intake ports. When seen from the upstream side in intake flow direction, the opening 5A connected to the intake port 3A disposed on the upper side is arranged farther than the opening 5B connected to the intake port 3B disposed on the lower side. The EGR device 17 returns the EGR gas to the intake port 3A disposed on the upper side.

Description

  The present invention relates to an exhaust gas recirculation device for an internal combustion engine.

  In order to reduce NOx emissions and pump loss of an internal combustion engine, a technique for returning a part of the exhaust gas as EGR gas to the intake air is effective. However, if the EGR gas amount is increased, the fuel does not burn well and PM There is a trade-off that the amount of emissions increases, and there is a problem that the EGR rate cannot be increased to some extent. On the other hand, a technique has been proposed in which EGR gas and air are stratified in the combustion chamber to increase the EGR rate without deteriorating combustion.

  For example, in Patent Document 1, two intake ports are provided per cylinder, EGR gas is supplied to only one of the two intake ports, and the intake port to which EGR gas is supplied flows into the combustion chamber. By arranging and configuring the gas to swirl along the outer periphery of the combustion chamber, and by arranging and configuring the intake port to which EGR gas is not supplied so that the gas flowing into the combustion chamber swirls through the center of the combustion chamber A technique is described in which an air layer is formed in the center of the combustion chamber, an EGR gas layer is formed so as to surround the outer periphery of the air layer, and the EGR gas and air are stratified in the combustion chamber.

JP 2008-101544 A

  In the technique described in Patent Document 1, the EGR gas layer is mainly formed in the vicinity of the inner wall surface of the combustion chamber by the swirl flow, and the air layer is formed in the vicinity of the central axis of the combustion chamber. An air layer is also formed in the lower region of the combustion chamber near the central axis, particularly near the top surface of the piston, but even if an EGR gas layer is formed in this region, the influence on fuel combustion is small. Therefore, if an EGR gas layer can be formed also in the region near the top surface of the piston below the combustion chamber, it is considered that the EGR rate can be further increased while suppressing deterioration of combustion.

  The present invention has been made in view of this point, and enables an EGR rate to be further increased while suppressing deterioration of combustion in an exhaust gas recirculation device for an internal combustion engine that stratifies EGR gas and air in a combustion chamber. The purpose is to provide technology.

In order to achieve this object, an exhaust gas recirculation apparatus for an internal combustion engine according to the present invention comprises:
An exhaust gas recirculation device for an internal combustion engine comprising an EGR device for recirculating a part of exhaust gas of the internal combustion engine as EGR gas to an intake system,
The internal combustion engine includes two intake ports that can form a tumble flow in the same direction in the cylinder,
The two intake ports are arranged in parallel in the vertical direction along the same virtual plane parallel to the cylinder central axis.
The two openings provided in the upper part of the cylinder to which the two intake ports are connected are connected to the intake port disposed on the upper side of the two intake ports when viewed from the upstream side in the direction of intake air flow. The opening to be provided is provided farther than the opening to which the intake port disposed on the lower side of the two intake ports is connected,
The EGR device recirculates EGR gas to an intake port arranged on the upper side.

  The opening to which the upper intake port is connected is provided farther when viewed from the upstream side in the direction of the intake air flow than the opening to which the lower intake port is connected. The tumble flow formed by the gas flowing from the intake port into the cylinder is formed inside the tumble flow formed by the gas flowing from the upper intake port into the cylinder. As a result, the gas flowing into the cylinder from the lower intake port turns around the cylinder center axis, and the gas flowing into the cylinder from the upper intake port turns outside the cylinder. As a result, the gas distribution in the cylinder is localized in the area above the center of the cylinder where the gas flowing into the cylinder from the lower intake port stays and is located in the area around and below the cylinder inner wall. In addition, the gas flowing into the cylinder from the upper intake port stays in the vicinity of the top surface of the piston and becomes a stratified gas distribution localized.

  In the configuration of the present invention, since the EGR gas recirculates only to the upper intake port, the gas distribution in the cylinder is such that air or a mixture of air and fuel is localized in the region above the center of the cylinder, and the inner wall surface of the cylinder The stratified gas distribution is such that the EGR gas is localized near the piston top surface. Since the spark plug is provided in the upper center part of the cylinder (near the cylinder center axis), a layer of air or a combustible mixture is formed around the spark plug, and an EGR gas layer is formed so as to enclose it. Accordingly, the EGR gas layer can be formed not only in the vicinity of the cylinder inner wall surface but also in the vicinity of the piston top surface below the cylinder that does not easily affect the combustibility, so that more EGR gas can be suppressed while suppressing the deterioration of combustion. Can be refluxed.

  In the present invention, a first fuel injection valve that injects fuel into the lower intake port may be provided.

  In this configuration, since it is possible to suppress the fuel from being mixed into the EGR gas layer formed near the inner wall surface of the cylinder and near the piston top surface below the cylinder, the discharge of unburned components can be suppressed.

In the present invention, a second fuel injection valve that injects fuel into the upper intake port;
The first fuel injection valve is configured such that fuel is injected only by the first fuel injection valve and fuel injection by the second fuel injection valve is not performed under an operating condition in which EGR gas is recirculated by the EGR device. And control means for controlling the second fuel injection valve.

  Also in this configuration, since it is possible to suppress the fuel from being mixed into the EGR gas layer formed near the cylinder inner wall surface and near the piston top surface below the cylinder, it is possible to suppress the discharge of unburned components. Under an operating condition in which the EGR gas is not recirculated, fuel injection by the second fuel injection valve may be performed.

In the present invention, a partition that divides the interior of a predetermined section in the vicinity of the connection portion with at least the opening of the upper intake port in the vertical direction to form an upper passage and a lower passage,
A blocking means capable of blocking gas inflow from the upstream side of the partition wall of the upper intake port to the lower passage;
A second control unit that controls the blocking unit so as to block the inflow of the gas to the lower passage under an operating condition in which the EGR gas is recirculated by the EGR device;

In this configuration, since the EGR gas flows into the cylinder only from the upper passage of the upper intake port, the tumble flow of the EGR gas swirls outside the tumble flow of the gas flowing into the cylinder from the lower intake port. To do. Therefore, mixing of the EGR gas flowing in from the upper intake port and the air or air-fuel mixture flowing in from the lower air intake port can be avoided more reliably, and the air or air-fuel mixture layer above the center in the cylinder Thus, the EGR gas layer near the inner wall surface of the cylinder and the top surface of the piston below the cylinder is more reliably stratified. Accordingly, it is possible to increase the EGR rate while more reliably suppressing the deterioration of combustion.

  In the present invention, the two openings to which the two intake ports are connected can be arranged along a plane perpendicular to the crankshaft of the internal combustion engine. In this case, since the direction of the intake air flow in the intake port and the direction of the intake air flow from the intake system side such as the intake manifold to the intake port can be made parallel, the connection between the intake port and the intake manifold is simplified. .

  In the present invention, the two openings to which the two intake ports are connected can be arranged along a plane parallel to the crankshaft of the internal combustion engine. In this case, since the arrangement of the two intake ports can be made parallel to the cylinder arrangement, a valve mechanism in an existing internal combustion engine can be used.

  According to the present invention, in an exhaust gas recirculation apparatus for an internal combustion engine that stratifies EGR gas and air in a combustion chamber, it is possible to further increase the EGR rate while suppressing deterioration of combustion.

1 is a diagram illustrating a schematic configuration of an internal combustion engine according to a first embodiment. It is a figure which shows schematic structure of the internal combustion engine which concerns on an Example, and gas distribution formed in a combustion chamber, and is a figure which shows the AA cross section of FIG. It is a figure which shows the gas distribution formed in the combustion chamber of the internal combustion engine which concerns on an Example, and is a figure which shows the BB cross section of FIG. FIG. 2 is a diagram illustrating a schematic configuration of the internal combustion engine according to the first embodiment, and is a diagram illustrating a cross-section AA in FIG. 1. FIG. 3 is a diagram illustrating a schematic configuration of an internal combustion engine according to a second embodiment. FIG. 6 is a diagram illustrating a schematic configuration of an internal combustion engine according to a second embodiment, and is a diagram illustrating a CC cross section of FIG. 5. FIG. 6 is a diagram illustrating a schematic configuration of an internal combustion engine according to a third embodiment. It is a figure which shows schematic structure of the internal combustion engine which concerns on Example 3, and is a figure which shows DD cross section of FIG. FIG. 6 is a diagram illustrating a schematic configuration of an internal combustion engine according to a fourth embodiment. FIG. 10 is a diagram illustrating a schematic configuration of an internal combustion engine according to a fourth embodiment, and is a diagram illustrating an EE cross section of FIG. 9. FIG. 3 is a diagram illustrating a schematic configuration of an internal combustion engine according to a modification of the first embodiment. FIG. 6 is a diagram illustrating a schematic configuration of an internal combustion engine according to a modification of the second embodiment. FIG. 10 is a diagram illustrating a schematic configuration of an internal combustion engine according to a modification of the third embodiment. FIG. 10 is a diagram illustrating a schematic configuration of an internal combustion engine according to a modification of the fourth embodiment.

  Hereinafter, embodiments of the present invention will be described in detail. The dimensions, materials, shapes, relative arrangements, and the like of the components described in the present embodiment are not intended to limit the technical scope of the invention to those unless otherwise specified.

Example 1
FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine according to a first embodiment of the present invention. As shown in FIG. 1, the internal combustion engine 1 is an in-line four-cylinder engine including four cylinders 2 and includes a crankshaft 11 (not shown) along the direction of the cylinder arrangement. The left side of the drawing represents the intake side provided with an unillustrated intake manifold, and the right side of the drawing represents the exhaust side provided with an unillustrated exhaust manifold.

  Two openings 5A and 5B provided along the virtual plane perpendicular to the crankshaft 11 (virtual plane parallel to the central axis C of the cylinder 2) at the top of each cylinder 2 communicate with the combustion chamber in the cylinder. Two intake ports 3A, 3B are connected, and two openings 6A, 6B provided along the virtual plane parallel to the center axis C of the crankshaft 11 and the cylinder 2 at the top of each cylinder 2 are connected to the inside of the cylinder. Two exhaust ports 4A and 4B communicating with the combustion chamber are connected.

  The intake ports 3A and 3B are both connected to an intake manifold provided in the intake system on the left side of the drawing, and the exhaust ports 4A and 4B are both connected to an exhaust manifold provided in the exhaust system on the right side of the drawing. As shown in FIG. 1, when viewed from the upstream side in the direction of intake air, that is, the direction of intake air flow, the opening 5A to which the intake port 3A is connected is more than the opening 5B to which the intake port 3B is connected. , Provided far away. The other three cylinders have the same configuration.

  FIG. 2 is a diagram showing a schematic configuration of the internal combustion engine according to the present embodiment, and is a diagram showing an AA cross section of FIG. In FIG. 2, the exhaust ports 4A and 4B are not shown in order to avoid the complexity of the drawing. As shown in FIG. 2, a piston 16 is slidably inserted into the cylinder 2 and a combustion chamber 20 is defined by the top surface of the piston 16 and the inner wall surface of the cylinder 2.

  As shown in FIG. 2, the intake ports 3 </ b> A and 3 </ b> B of this embodiment are arranged in parallel in the vertical direction along the same virtual plane including the central axis C of the cylinder 2, and have the same orientation in the combustion chamber 20. It is configured in a shape capable of forming a tumble flow. As described above, the opening 5A is arranged farther than the opening 5B in the direction of intake air flow when viewed from the upstream side, and is thus formed by the gas flowing in from the lower intake port 3B. The tumble flow FB is formed inside the tumble flow FA formed by the gas flowing in from the upper intake port 3A.

  As a result, the gas cylinder swirls around the central axis C of the gas cylinder flowing into the combustion chamber 20 from the lower intake port 3B, and the gas flowing into the combustion chamber 20 from the upper intake port 3A swirls outside thereof. As a result, as shown in FIG. 2, the gas distribution in the combustion chamber 20 is localized in the region above the central portion of the combustion chamber 20 where the gas GB flowing from the lower intake port 3B stays. The gas GA flowing from the upper intake port 3A stays in the vicinity of the inner wall surface of the combustion chamber 20 and the vicinity of the top surface of the piston 16, which is a lower region, and the stratified gas distribution is localized.

  FIG. 3 is a view showing a gas distribution formed in the combustion chamber of the internal combustion engine according to this embodiment, and is a view showing a BB cross section of FIG. As shown in FIG. 3, a layer of gas GB flowing from the lower intake port 3B is formed in the vicinity of the cylinder center axis C, and gas flowing from the upper intake port 3A in the vicinity of the inner wall surface of the combustion chamber 20 on the outer side. It has a stratified gas distribution in which a GA layer is formed.

  FIG. 4 is a diagram showing a schematic configuration of the internal combustion engine according to the present embodiment, and is a diagram showing an AA cross section of FIG. The opening 5A opened at the top of the combustion chamber 20 is opened and closed by the intake valve 8A, and the opening 5B is opened and closed by the intake valve 8B. An ignition plug 14 for igniting the air-fuel mixture in the combustion chamber is provided near the central axis at the top of the combustion chamber 20. An EGR passage 17 that recirculates a part of the exhaust gas of the internal combustion engine 1 as EGR gas is connected to the upper intake port 3A. The EGR passage 17 is provided with an EGR valve 18 that opens and closes the EGR passage 17. A control valve 19 for controlling the inflow of air from the intake passage to the upper intake port 3A is provided on the upstream side of the connection portion of the EGR passage 17 in the upper intake port 3A.

  Further, a fuel injection valve 7B for injecting fuel into the lower intake port 3B is provided. The operations of the EGR valve 18, the control valve 19, the fuel injection valve 7B, and the spark plug 14 are controlled by the ECU 15. The ECU 15 is a computer that controls the operation of the internal combustion engine 1. The ECU 15 acquires the operating state of the internal combustion engine 1 such as the rotational speed and load by various sensors (not shown), and based on this, the fuel injection valve 7B, the spark plug 14, and other various devices. To control the operation.

  Thus, when the EGR valve 18 is opened, the EGR gas flows into the combustion chamber 20 only from the upper intake port 3A, and the fuel / air mixture enters the combustion chamber 20 only from the lower intake port 3B. Inflow. Therefore, as shown in FIG. 4, the gas distribution in the combustion chamber 20 is such that an air-fuel mixture layer Gm flowing from the lower intake port 3 </ b> B is formed in a region above the central portion of the combustion chamber 20. This is a stratified gas distribution in which a layer Ge of EGR gas flowing from the upper intake port 3A is formed in the vicinity of the inner wall surface of the combustion chamber 20 and in the vicinity of the top surface of the piston 16.

  Further, when the EGR valve 18 is opened and the control valve 19 is closed, air does not flow into the upper intake port 3A from the intake passage, so that the upper intake port 3A enters the combustion chamber 20. The inflowing gas may be only EGR gas. In this case, a gas layer composed only of EGR gas is formed near the inner wall surface of the combustion chamber 20 and near the top surface of the piston 16.

  As shown in FIG. 11, either EGR gas is allowed to flow from the EGR passage 17 to the upper intake port 3A or air is allowed to flow from the intake passage to the upper intake port 3A. The same effect can be obtained by providing the switching valve 21 that can be switched between the EGR passage 17 and controlling the switching valve 21 so that the EGR gas flows from the EGR passage 17 into the upper intake port 3A.

  Further, under the operating condition in which the EGR gas is not recirculated, the switching valve 21 is controlled so that the EGR valve 18 is closed or a flow path for flowing air from the intake passage to the upper intake port 3A is selected. It ’s fine.

  As a result, the combustible air-fuel mixture can be concentrated and localized around the spark plug 14, so that deterioration of combustion can be suppressed even if a large amount of EGR gas is recirculated. Even if it is near the cylinder center axis C and near the top surface of the piston 16 below the combustion chamber, even if an EGR gas layer is formed, combustion is unlikely to deteriorate.

  According to the configuration of the present embodiment, the EGR gas layer Ge can be formed not only near the inner wall surface of the combustion chamber 20 around the gas mixture layer Gm but also near the top surface of the piston 16 below the combustion chamber 20. Therefore, it is possible to recirculate more EGR gas while suppressing deterioration of combustion, and it is possible to further increase the EGR rate. Further, since the fuel is supplied only to the lower intake port 3B, the fuel is not present in the EGR gas layer Ge. Therefore, discharge of unburned components can be suppressed.

(Example 2)
FIG. 5 is a diagram showing a schematic configuration of an internal combustion engine according to the second embodiment of the present invention. Hereinafter, the difference from the first embodiment will be mainly described. As shown in FIG. 5, in the internal combustion engine 1 of this embodiment, the openings 5C and 5D to which the intake ports 3C and 3D are connected are perpendicular to the crankshaft 11 and the cylinder 2 as in the openings 5A and 5B of the first embodiment. Unlike the openings 6A and 6B of the first embodiment, the openings 6C and 6D to which the exhaust ports 4C and 4D are connected are perpendicular to the crankshaft 11 and are arranged along the imaginary plane parallel to the central axis C of the cylinder 2. Are provided along a virtual plane parallel to the central axis C (different from the virtual plane along which the openings 5C and 5D are located).

The opening 5C to which the intake port 3C is connected is provided farther than the opening 5D to which the intake port 3D is connected when viewed from the upstream side in the intake side, that is, the direction of intake air flow. . The other three cylinders have the same configuration.

  FIG. 6 is a diagram showing a schematic configuration of the internal combustion engine according to the present embodiment, and is a diagram showing a CC cross section of FIG. In FIG. 6, the exhaust ports 4C and 4D are not shown in order to avoid complicated drawings. In this embodiment, the opening 5C is opened and closed by the intake valve 8C, and the opening 5D is opened and closed by the intake valve 8D.

  As in the first embodiment, the intake ports 3C and 3D are arranged in parallel in the vertical direction along a virtual plane parallel to the central axis C of the cylinder 2, and have a shape capable of forming a tumble flow in the same direction. The opening 5C to which the upper intake port 3C is connected is arranged farther when viewed from the upstream side in the direction of intake air flow than the opening 5D to which the lower intake port 3D is connected. Therefore, the gas flowing in from the upper intake port 3C is localized near the inner wall surface of the combustion chamber 20 and near the top surface of the piston 16, and the gas flowing in from the lower intake port 3D is ignited above the center of the combustion chamber 20. It is localized near the plug 14.

  In the present embodiment, as in the first embodiment, the EGR passage 17 is connected only to the upper intake port 3C, and the EGR gas flows into the combustion chamber 20 only through the upper intake port 3C. The EGR passage 17 is provided with an EGR valve 18 that adjusts the flow rate of EGR gas flowing from the EGR passage 17 into the upper intake port 3C. Further, a control valve 19 for controlling the inflow of air from the intake passage to the upper intake port 3A is provided on the upstream side of the connection portion of the EGR passage 17 in the upper intake port 3A.

  Also in this embodiment, as shown in FIG. 12, either the EGR gas is allowed to flow from the EGR passage 17 to the upper intake port 3C or the air is allowed to flow from the intake passage to the upper intake port 3C. It can also be set as the structure provided with the switching valve 22 which can be selectively switched to this flow path.

  In this embodiment, fuel injection valves are provided in both the upper intake port 3C and the lower intake port 3D (fuel injection valves 7C and 7D). Then, the ECU 15 closes the EGR valve 18 under the operating condition in which the EGR gas is not recirculated, and performs fuel injection by both the fuel injection valves 7C and 7D. In the case of the configuration provided with the switching valve 22 shown in FIG. 12, the switching valve is selected so that the flow path through which air flows from the intake passage to the upper intake port 3 </ b> C is selected under the operating condition in which the EGR gas does not recirculate. 22 may be controlled.

  On the other hand, under the operating conditions for recirculating EGR gas, the EGR valve 18 is opened to recirculate EGR gas to the upper intake port 3C, and fuel is injected only by the fuel injection valve 7D, and fuel injection by the fuel injection valve 7C is performed. Control is performed so as not to perform. In the case of the configuration provided with the switching valve 22 shown in FIG. 12, switching is performed so that the flow path for flowing the EGR gas from the EGR passage 17 to the upper intake port 3C is selected under the operating condition for recirculating the EGR gas. The valve 22 may be controlled. In this case, only EGR gas can flow into the combustion chamber 20 from the upper intake port 3C. The ECU 15 that performs this control functions as the control means in the present invention. The fuel injection valve 7D functions as the first fuel injection valve of the present invention, and the fuel injection valve 7C functions as the second fuel injection valve of the present invention.

  By performing such control by the ECU 15, even in a configuration in which the fuel injection valves are provided in both of the two intake ports 3 </ b> C and 3 </ b> D, the fuel is supplied to the layer GR of the EGR gas in the stratified gas distribution formed in the combustion chamber 20. Since it can suppress mixing, discharge | emission of an unburned component can be suppressed.

  Then, a fuel / air mixture layer Gm is formed around the spark plug 14 above the center of the combustion chamber 20, and the fuel is applied to the periphery and the vicinity of the inner wall surface of the combustion chamber 20 and the top surface of the piston 16. Since the EGR gas layer Ge not included can be formed, deterioration of combustion can be suppressed even if the amount of recirculation of the EGR gas is increased. Therefore, it is possible to increase the EGR rate while suppressing deterioration of combustion.

(Example 3)
FIG. 7 is a diagram showing a schematic configuration of an internal combustion engine according to a third embodiment of the present invention. Hereinafter, the difference from the first and second embodiments will be mainly described. As shown in FIG. 7, in the internal combustion engine 1 of the present embodiment, the lower intake port 3D, the two exhaust ports 4C, 4D, and the openings 5D, 6C provided in the upper part of the combustion chamber 20 to which these are connected, 6D is the same as that in the second embodiment.

  The difference between the present embodiment and the second embodiment is an upper intake port 3C1 connected to the opening 5C. As shown in FIG. 7, in this embodiment, the upstream section of the upper intake port 3C1 is the same virtual plane as the lower intake port 3D (parallel to the central axis C of the cylinder 2 and perpendicular to the crankshaft 11). Are not arranged along a virtual plane). However, since the relatively short section near the connection portion with the opening 5C is arranged in the same virtual plane as the lower intake port 3D, as shown in FIG. 8 which is a diagram showing a DD cross section of FIG. The intake port configuration is the same as that of the second embodiment.

  Also in this embodiment, instead of the EGR valve 18 and the control valve 19, as shown in FIG. 13, EGR gas is allowed to flow from the EGR passage 17 to the upper intake port 3C1, or from the intake passage to the upper intake port. It is good also as a structure provided with the switching valve 23 which can selectively switch to any flow path of making air flow into 3C1.

  As shown in FIG. 8, the characteristic configuration of this embodiment is that the interior of a predetermined section in the vicinity of the connection portion with the opening 5C of the upper intake port 3C1 is vertically divided, and the upper passage 3C2 and the lower passage 3C3 are divided. A partition wall 9 to be formed and a shutoff valve 10 capable of blocking the inflow of gas from the upstream side to the lower passage 3C3 from the partition wall 9 of the upper intake port 3C1 are provided.

  When the shutoff valve 10 is opened, the gas in the upper intake port 3C1 passes through both the upper passage 3C2 and the lower passage 3C3 and flows into the combustion chamber 20, and when the shutoff valve 10 is closed, only the upper passage 3C2 is opened. The gas in the upper intake port 3C1 passes through and flows into the combustion chamber 20. FIG. 8 shows a case where the shutoff valve 10 is closed. Then, the ECU 15 performs control so that the EGR valve 18 is opened and the shutoff valve 10 is closed under the operating condition in which the EGR gas is recirculated. In this embodiment, the shut-off valve 10 functions as the shut-off means of the present invention, and the ECU 15 that performs the control functions as the second control means of the present invention.

  The EGR gas flowing into the combustion chamber 20 from the upper passage 3C2 of the upper intake port 3C2 swirls further outside the tumble flow of the gas flowing into the combustion chamber 20 from the lower intake port 3D. Mixing of the air-fuel mixture flowing from the port 3D and the EGR gas flowing from the upper intake port 3C1 can be avoided more reliably. If the EGR valve 18 is opened and the control valve 19 is closed, only the EGR gas flows into the combustion chamber 20 from the upper intake port 3C1. In the case of the configuration including the switching valve 23 of FIG. 13, the same effect can be obtained by controlling the switching valve 23 so that the flow path through which the EGR gas flows from the EGR passage 17 to the upper intake port 3C1 is selected. Is obtained.

Therefore, the air-fuel mixture layer Gm formed above the center of the combustion chamber 20 and the EGR gas layer Ge formed near the inner wall surface of the combustion chamber 20 and near the top surface of the piston 16 below the combustion chamber 20. More reliable stratification. Therefore, it is possible to increase the EGR rate while more reliably suppressing the deterioration of combustion and the discharge of unburned components.

Example 4
FIG. 9 is a diagram showing a schematic configuration of an internal combustion engine according to the fourth embodiment of the present invention. Hereinafter, the difference from the first to third embodiments will be mainly described. As shown in FIG. 9, in the internal combustion engine 1 of the present embodiment, the openings 5E and 5F to which the intake ports 3E and 3F are connected are in a virtual plane parallel to the crankshaft 11 and parallel to the central axis C of the cylinder 2. Along the upper part of the combustion chamber. The openings 6E and 6F to which the exhaust ports 4E and 4F are connected are also provided in the upper portion of the combustion chamber along a virtual plane parallel to the crankshaft 11 and parallel to the center axis C of the cylinder 2 (openings 5E and 5F). Is different from the virtual plane along the

  In this embodiment, as shown in FIG. 9, the intake ports 3E and 3F are arranged so that the direction of the intake air flowing through the intake ports 3E and 3F is along the cylinder arrangement direction. An opening arranged in parallel in the vertical direction along the same virtual plane parallel to the central axis C of the cylinder 2 and connected to the intake port 3E when viewed from the rear side, that is, the upstream side in the direction of intake air flow The part 5E is configured to be provided farther than the opening 5F to which the intake port 3F is connected. The other three cylinders have the same configuration.

  FIG. 10 is a diagram showing a schematic configuration of the internal combustion engine according to the present embodiment, and is a diagram showing an EE cross section of FIG. In FIG. 10, the illustration of the exhaust ports 4E and 4F is omitted in order to avoid the complexity of the drawing. In this embodiment, the opening 5E is opened and closed by the intake valve 8E, and the opening 5F is opened and closed by the intake valve 8F.

  As in the first to third embodiments, the intake ports 3E and 3F are arranged in parallel in the vertical direction along a virtual plane parallel to the central axis C of the cylinder 2 and can form a tumble flow in the same direction. The opening 5E to which the upper intake port 3E is connected is arranged farther when viewed from the upstream side in the direction of intake air flow than the opening 5F to which the lower intake port 3F is connected. Therefore, the gas flowing in from the upper intake port 3E is localized near the inner wall surface of the combustion chamber 20 and near the top surface of the piston 16, and the gas flowing in from the lower intake port 3F is above the central portion of the combustion chamber 20. Near the spark plug 14.

  In the present embodiment, the EGR passage 17 is connected only to the upper intake port 3E, and EGR gas flows into the combustion chamber 20 only through the upper intake port 3E. Like the upper intake port 3C1 of the third embodiment, the upper intake port 3E is provided with a partition wall 9 in the vicinity of the connection portion with the opening 5E, and is partitioned into an upper passage 3E1 and a lower passage 3E2. A shutoff valve 10 is provided that can shut off the inflow of gas into the lower passage 3E2. The EGR passage 17 is provided with an EGR valve 18 that opens and closes the EGR passage 17. A control valve 19 that controls the inflow of air from the intake passage 3 to the upper intake port 3E is provided on the upstream side of the connection portion of the EGR passage 17 in the upper intake port 3E.

  As shown in FIG. 14, the flow path is selected from the EGR passage 17 to either the EGR gas flowing into the upper intake port 3E or the air from the intake passage 3 to the upper intake port 3E. It is also possible to employ a configuration provided with a switching valve 24 that can be switched automatically.

  In the present embodiment, the fuel injection valve 7 is provided in the intake passage 3 upstream from the portion branched into the upper intake port 3E and the lower intake port 3F. Therefore, in this embodiment, when the control valve 19 is opened, and when the switching valve 24 is controlled so that a flow path through which air flows from the intake passage 3 to the upper intake port 3E is selected, the fuel is on the upper side. It flows into both the intake port 3E and the lower intake port 3F.

  Therefore, in the present embodiment, the gas distribution formed in the combustion chamber 20 is a region near the spark plug 14 above the center of the combustion chamber 20 due to the mixed gas of air and fuel flowing from the lower intake port 3F. And a layer Ge formed near the inner wall surface of the combustion chamber 20 and near the top surface of the lower piston 16 by the mixed gas of EGR gas and fuel flowing from the upper intake port 3E. It becomes gas distribution. In this case, although fuel is mixed into the EGR gas layer Ge, a combustible mixture of only air and fuel that does not contain EGR gas is localized in the vicinity of the spark plug 14, so that good combustion is achieved. Is done. Therefore, the EGR rate can be increased while suppressing deterioration of combustion.

  It should be noted that, when the EGR valve 18 is opened and the control valve 19 is closed under the operating conditions for recirculating the EGR gas, and the flow path through which the EGR gas flows from the EGR passage 17 to the upper intake port 3E is selected. When the switching valve 24 is controlled so that fuel and air do not flow from the intake port 3E.

  Each example described above is intended to exemplify the embodiment of the present invention, and can be combined and modified as much as possible within the scope of the present invention. For example, the present invention can be applied to an engine other than a four-cylinder in-line engine, and can also be applied to a direct injection internal combustion engine. When applied to a direct injection internal combustion engine, it is preferable to inject fuel toward the layer formed by the gas flowing into the combustion chamber from the lower intake port.

  In addition, a virtual plane along which two openings to which two intake ports are connected and a virtual plane in which two intake ports are arranged in parallel along the crank plane are parallel to the cylinder center axis. It does not have to be parallel or perpendicular to the shaft. Also, there is no need for two exhaust ports. The opening to which the intake port is connected and the opening to which the exhaust port is connected are substantially the same size in the drawing of the embodiment, but this is not restrictive.

  The EGR passage may be individually connected to the upper intake port of each cylinder, or the first intake manifold to which only the upper intake port of each cylinder is connected, and only the lower intake port of each cylinder is connected. The EGR gas may be recirculated to the first intake manifold by connecting an EGR passage to the first intake manifold.

1 Internal combustion engine 2 Cylinder 3 Intake passage 3A Upper intake port 3C Upper intake port 3C1 Upper intake port 3E Upper intake port 3C2 Upper passage 3E1 Upper passage 3C3 Lower passage 3E2 Lower passage 3B Lower intake port 3D Below Lower intake port 3F Lower intake port 4A Exhaust port 4B Exhaust port 4C Exhaust port 4D Exhaust port 4E Exhaust port 4F Exhaust port 5A Opening 5B Opening 5C Opening 5D Opening 5E Opening 5F Opening 6A Opening 6B Opening 6C opening 6D opening 6E opening 6F opening 7 fuel injection valve 7A fuel injection valve 7B fuel injection valve 7C fuel injection valve 7D fuel injection valve 8A intake valve 8B intake valve 8C intake valve 8D intake valve 8E intake valve 8F Intake valve 9 Bulkhead 10 Shut-off valve 11 Crankshaft 14 Spark plug 15 CU
16 Piston 17 EGR passage 18 EGR valve 19 Control valve 20 Combustion chamber 21 Switching valve 22 Switching valve 23 Switching valve 24 Switching valve

Claims (6)

An exhaust gas recirculation device for an internal combustion engine comprising an EGR device for recirculating a part of exhaust gas of the internal combustion engine as EGR gas to an intake system,
The internal combustion engine includes two intake ports that can form a tumble flow in the same direction in the cylinder,
The two intake ports are arranged in parallel in the vertical direction along the same virtual plane parallel to the cylinder central axis.
The two openings provided in the upper part of the cylinder to which the two intake ports are connected are connected to the intake port disposed on the upper side of the two intake ports when viewed from the upstream side in the direction of intake air flow. The opening to be provided is provided farther than the opening to which the intake port disposed on the lower side of the two intake ports is connected,
The exhaust gas recirculation device for an internal combustion engine, wherein the EGR device recirculates EGR gas to an intake port disposed on the upper side. In claim 1,
An exhaust gas recirculation device for an internal combustion engine, comprising: a first fuel injection valve that injects fuel into the lower intake port. In claim 2,
A second fuel injection valve for injecting fuel into the upper intake port;
The first fuel injection valve is configured such that fuel is injected only by the first fuel injection valve and fuel injection by the second fuel injection valve is not performed under an operating condition in which EGR gas is recirculated by the EGR device. And control means for controlling the second fuel injection valve;
An exhaust gas recirculation device for an internal combustion engine. In any one of Claim 1 to 3,
A partition that vertically divides the inside of a predetermined section in the vicinity of the connection portion with at least the opening of the upper intake port to form an upper passage and a lower passage;
A blocking means capable of blocking gas inflow from the upstream side of the partition wall of the upper intake port to the lower passage;
A second control means for controlling the shut-off means so as to shut off the inflow of gas into the lower passage, under operating conditions in which the EGR gas is recirculated by the EGR device;
An exhaust gas recirculation device for an internal combustion engine. In any one of Claims 1-4,
An exhaust gas recirculation device for an internal combustion engine, wherein two openings to which the two intake ports are connected are arranged along a plane perpendicular to the crankshaft of the internal combustion engine. In any one of Claims 1-4,
The exhaust gas recirculation apparatus for an internal combustion engine, wherein the two openings to which the two intake ports are connected are arranged along a plane parallel to the crankshaft of the internal combustion engine.

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