JP2018100620A - Control device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a bias of fuel in a combustion chamber.SOLUTION: A control device for an engine includes an intake port 3 and an exhaust port 4 connected to a combustion chamber 2 of an engine 1, a fuel injection valve 10 arranged in the intake port 3 so as to inject fuel, a partition wall 11 partitioning the inside of the intake port 3 into an upper port 14 and a lower port 13, and an ignition device 7 for combusting fuel supplied into the combustion chamber 2, and the fuel injection valve 10 is disposed in the lower port 13. A cross sectional area of the upper port 14 is equal to or larger than a cross sectional area of the lower port 13. Intake air relatively thin in fuel concentration is supplied from an upper space in the combustion chamber 2 toward a space in the exhaust port 4 side through the upper port 14, and a tumble flow is formed, and intake air relatively thick in the fuel concentration is supplied toward a lower space in the combustion chamber 2 through the lower port 13.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an engine control device having an intake passage structure that enables good combustion in a combustion chamber.

  Intake air is supplied into the combustion chamber of the engine through an intake passage (hereinafter referred to as an intake port) provided in the cylinder head. In addition, a fuel injection valve is provided in the intake port, and the fuel injected from the fuel injection valve diffuses in the combustion chamber together with the intake air, and the diffused fuel is ignited and burned by an ignition plug provided in the combustion chamber. To do.

  For example, in Patent Document 1, the fuel injection valves respectively provided in the two intake ports are set so as to face the ignition plug in the combustion chamber. The fuel injected into the combustion chamber at a relatively low pressure during the intake stroke and directed toward the spark plug collides near the center of the combustion chamber near the spark plug (near the center in plan view), and near the center of the combustion chamber A rich air-fuel mixture is formed and stratified.

  In addition, fuel injection is distributed in two directions by two fuel injection valves provided separately for the two intake ports, so that even if the fuel injection amount increases, it adheres to the umbrella portion or stem of the intake valve It is said that the amount of fuel is small, mixing of intake air and fuel is promoted, and vaporization atomization is improved.

  Further, a swirl flow in the circumferential direction is formed along the inner peripheral surface of the combustion chamber, and in addition to the fuel injection in the two directions, fuel is also injected in the direction of the swirl flow. And fuel mixing is further promoted.

Japanese Patent Laid-Open No. 6-249109

  In general, the fuel injected from the fuel injection valve in the intake port is pierced by its penetrating force, on the opposite side from the intake passage, ie, the exhaust passage (hereinafter referred to as the exhaust port) across the vicinity of the center of the combustion chamber in plan view. ) There is a tendency to go straight to the side. If the fuel has a strong tendency to go straight to the exhaust port side, the space near the exhaust port in the combustion chamber becomes rich in fuel and the space near the intake port becomes lean in fuel. Such a fuel bias may inhibit homogeneous combustion in the combustion chamber and reduce combustion efficiency.

  In this regard, according to the technique of Patent Document 1, in addition to the fuel injection from the two fuel injection valves that collide near the center of the combustion chamber in plan view, the swirl flow along the inner peripheral surface of the combustion chamber and the swirl flow Since fuel injection is performed, the straight travel of fuel from the intake port side to the exhaust port side is suppressed to some extent.

  However, according to the technique of Patent Document 1, there is still a possibility that the fuel is biased in the combustion chamber under the operation condition where the swirl flow is weak or the operation condition where the swirl flow is not generated. In addition to the engine types having the two intake ports, the two fuel injection valves, and the swirl flow forming means as described above, there is a demand for suppressing the fuel bias in the combustion chamber as much as possible in various engine types. .

  Therefore, an object of the present invention is to suppress the bias of the fuel in the combustion chamber as much as possible.

  In order to solve the above problems, the present invention includes an intake port and an exhaust port connected to a combustion chamber of an engine, a fuel injection valve disposed in the intake port and injecting fuel, and an upper portion in the intake port. A partition that separates the port and the lower port, and an ignition device that combusts the fuel supplied into the combustion chamber, and the fuel injection valve employs an engine control device disposed in the lower port.

  Here, a configuration in which the cross-sectional area of the upper port is larger than the cross-sectional area of the lower port can be adopted.

  In addition, intake air having a relatively low fuel concentration is supplied from the upper space in the combustion chamber to the exhaust port side space through the upper port to form a tumble flow, and through the lower port, the intake gas is closer to the lower portion in the combustion chamber. A configuration in which intake air with a relatively high fuel concentration is supplied toward the space can be employed.

  In each of these aspects, an exhaust gas recirculation device for introducing a part of the exhaust gas discharged from the combustion chamber into the intake air as an exhaust recirculation gas is provided, and the inlet of the exhaust recirculation gas to the intake is provided in the upper port The configuration provided can be employed.

  The fuel injection by the fuel injection valve can be performed at the same time as the introduction of the exhaust gas recirculation gas from the introduction port or after the start of the introduction.

  In each of these aspects, an intake valve that opens and closes an opening of the intake port to the combustion chamber is provided, and fuel injection from the fuel injection valve includes injection at least in an intake stroke, and from the fuel injection valve It is possible to adopt a configuration in which the fuel injection direction is directed toward the back of the intake valve in the valve open state.

  It is possible to adopt a configuration in which the fuel injection direction from the fuel injection valve is directed closer to the fuel injection valve than the valve stem of the intake valve in the open state.

  A configuration may be adopted in which a downstream end of the partition wall is provided with a guide portion, and the guide portion guides the flow of intake air supplied from the lower port into the combustion chamber downward in the cylinder axis direction of the combustion chamber.

  In the present invention, the intake port is separated by the partition into the upper port and the lower port, and the fuel injection valve disposed in the intake port is disposed in the lower port. Therefore, the fuel injected from the lower port is discharged from the upper port. The straight intake to the exhaust side is suppressed by the supplied intake air. For this reason, the bias of the fuel in a combustion chamber can be suppressed.

(A) (b) (c) is a principal part longitudinal cross-sectional view which shows embodiment of this invention. It is sectional drawing of the intake port of FIG. (A) (b) is a principal part enlarged view which shows other embodiment. It is a top view of a combustion chamber vicinity. It is a principal part enlarged view which shows other embodiment.

  Embodiments of the present invention will be described with reference to the drawings. FIGS. 1A to 1C are longitudinal sectional views showing the vicinity of a combustion chamber 2 and a cylinder head of an engine 1 of this embodiment. FIG. 2 is a cross-sectional view of the intake port 3.

  As shown in FIG. 1A, a piston is accommodated in the cylinder of the engine 1. A combustion chamber 2 is formed by the upper surface of the cylinder, the inner peripheral surface, the upper surface of the piston, and the like. An upper cylinder head of the combustion chamber 2 is provided with an intake port 3 for sending intake air into the combustion chamber 2 and an exhaust port 4 drawn from the combustion chamber 2.

  In addition, a fuel injection valve (injector) 10 for injecting fuel into the combustion chamber 2 and the intake port 3 is provided in the intake port 3. Further, an ignition device 7 is provided at the top of the combustion chamber 2 to burn the fuel supplied into the combustion chamber 2.

  An intake valve hole that is an opening of the intake port 3 to the combustion chamber 2 is opened and closed by the intake valve 5. Similarly, an exhaust valve hole that is an opening of the exhaust port 4 to the combustion chamber 2 is also opened and closed by the exhaust valve 6.

  In these drawings, members and means on the intake side that are directly related to the present invention are mainly shown, and other members and the like are not shown. Although only one cylinder is shown in the drawings, the engine 1 may be a single cylinder or a multi-cylinder having a plurality of cylinders.

  As shown in FIG. 2, the intake port 3 has a cross-sectional shape in which the maximum diameter in the vertical direction connecting the upper surface side and the lower surface side of the passage is set to be smaller than the maximum diameter in the width direction perpendicular to the upper side. It has a horizontally long oval shape. Such an oval shape is in the section from the intake passage in the intake manifold arranged upstream of the intake port 3 to the vicinity of the valve support portion where the valve stem 5b of the intake valve 5 is supported by the cylinder head. continuing.

  On the upstream side of the intake valve 5 in the intake port 3, as shown in FIGS. 1A and 2, a partition wall 11 that divides the space in the intake port 3 into an upper port 14 and a lower port 13. Is provided. The partition wall 11 is provided in a range of a certain length with respect to the intake flow direction connecting the upstream side and the downstream side of the intake passage 3.

  As shown in FIG. 2, the partition wall 11 may be a plate-like member that linearly connects the inner walls in the width direction of the passage. In addition, the partition wall 11 may have a space between the inner walls in the width direction of the passage. It may be a plate-like member or the like tied in an arc shape along the bottom surface.

  The partition wall 11 does not necessarily need to airtightly separate the space in the upper port 14 and the space in the lower port 13. The partition wall 11 has a shape in which the fluid flow in the upper port 14 and the fluid flow in the lower port 13 are not greatly mixed with each other, and the fluid in each port 13, 14 is smoothly directed toward the combustion chamber 2. It only has to be provided at the position and range. For this reason, for example, the partition 11 may be provided continuously over the entire length between the inner walls in the width direction of the passage, or may be provided intermittently. Further, for example, the partition wall 11 may be provided continuously or intermittently with respect to the intake flow direction of the intake port 3.

  The fuel injection valve 10 disposed in the intake port 3 is disposed in the lower port 13. The fuel injection valve 10 is disposed so that the injection port faces the space in the lower port 13 from the bottom surface side of the intake port 3. From the injection port, fuel is injected toward the downstream side along the intake flow direction.

  A vehicle equipped with the engine 1 includes an electronic control unit 20. The electronic control unit 20 performs overall control of the engine 1 and auxiliary equipment including opening / closing control of the intake / exhaust valves 5 and 6, fuel injection control, ignition timing control, etc. Also controls.

  In the lower port 13, the fuel injected from the fuel injection valve 10 is supplied to the combustion chamber 2 together with the air from the upstream side. In addition, since fuel injection is not performed in the upper port 14, mainly air from the upstream side is supplied to the combustion chamber 2 as indicated by an arrow I in FIG.

  Here, in the cross section orthogonal to the intake flow direction of the intake port 3, the cross-sectional area of the upper port 14 is set to be equal to or larger than the cross-sectional area of the lower port 13. Since the upper port 14 functions as a main intake passage and the lower port 13 functions as an auxiliary intake passage, preferably, the cross-sectional area of the upper port 14 is several times larger than the cross-sectional area of the lower port 13 (for example, 2 to 2). It should be set larger.

  In the combustion chamber 2, the intake air from the upper port 14 passes through the space closer to the exhaust port 4 in the combustion chamber, which is directly under the electrode 7 a of the ignition device 7, as indicated by an arrow A in FIG. Supplied towards the space. The intake air from the upper port 14 has a relatively low fuel concentration compared to the intake air from the lower port 13.

  The intake air from the lower port 13 is supplied toward the lower space in the combustion chamber 2 as indicated by an arrow B in FIG. The intake air from the lower port 13 has a relatively high fuel concentration compared to the intake air from the upper port 14.

  The intake air containing a large amount of fuel from the lower port 13 is restrained from going straight to the exhaust side by the large amount of intake air supplied from the upper port 14. That is, the presence of intake air via the upper port 14 directly below the ignition device 7 and the exhaust valve 6 suppresses the straight travel of fuel via the lower port 13. For this reason, the bias of the fuel to the exhaust side in the combustion chamber 2 due to the penetration force of the fuel injected from the fuel injection valve 10 can be suppressed.

  Further, in this embodiment, the intake air supplied from the upper port 14 is reversed along the inner surface of the combustion chamber 2 as shown by an arrow C in FIG. As a result, a vertical tumble flow is formed in the combustion chamber 2. The tumble flow indicated by the arrow C wraps the intake air with much fuel supplied from the lower port 13 from the outside. As a result, as shown in FIG. 1 (c), a fuel rich portion b having a relatively high fuel concentration is formed in the center of the in-cylinder space in the combustion chamber 2, and the fuel concentration is relatively high so as to surround the periphery thereof. A low fuel lean portion a is formed. By such an action of the tumble flow, the bias of the fuel to the exhaust side in the combustion chamber 2 is further suppressed, and the mixing of the intake air and the fuel during the subsequent compression stroke and ignition timing is promoted.

  Further, in this embodiment, as shown in FIG. 1A, an exhaust gas recirculation device 8 that introduces a part of the exhaust gas discharged from the combustion chamber 2 to the exhaust port 4 side into the intake air as the exhaust gas recirculation gas. It has.

  An inlet 12 for intake of the exhaust gas recirculation gas is disposed in the upper port 14 of the intake port 3. The inlet 12 is arranged so that its opening faces from the upper surface side of the intake port 3 toward the space in the upper port 14. The exhaust gas recirculation gas is injected from the introduction port 12 toward the downstream side along the intake flow direction. Since the introduction port 12 includes a valve that can be freely opened and closed, when the valve is opened, the exhaust gas recirculation gas is introduced into the intake air according to the pressure state in the intake port 3.

  In addition to the introduction port 12 in the intake port 3, a main introduction port (not shown) for exhaust gas recirculation gas intake by the exhaust gas recirculation device 8 is provided in an intake passage further upstream than the intake port 3. You may have. This main inlet is disposed immediately downstream of the throttle valve that leads the negative pressure in the intake passage.

  By supplying the exhaust gas recirculation gas to the combustion chamber 2 through the upper port 14, the exhaust gas recirculation gas can be easily distributed to the outer peripheral portion of the fuel rich portion b. For this reason, the occurrence of knocking can be suppressed and the ignition timing can be advanced, so that an effect of improving engine performance and fuel consumption can be expected.

  The fuel injection by the fuel injection valve 10 is performed simultaneously with the start of the introduction of the exhaust gas recirculation gas from the inlet 12 or in the introduction thereof in one cycle including the intake stroke, the compression stroke, the combustion process, and the exhaust stroke of the engine 1. It is set to take place after the start. In particular, the fuel injection by the fuel injection valve 10 is preferably performed after the introduction of the exhaust gas recirculation gas from the introduction port 12 is started. Since the exhaust gas recirculation gas can reach the upper space in the combustion chamber 2 and the exhaust port side space earlier than the injected fuel, the effect of suppressing the straight travel of the intake air containing a large amount of fuel to the exhaust side is enhanced. Because.

  FIGS. 3A and 3B show an embodiment in which the exhaust recirculation gas inlet 12 is not installed in the upper port 14. As described above, even in an aspect in which the exhaust gas recirculation gas is not introduced into the upper port 14, the intake air supplied from the upper port 14 (see arrow A ′ in the drawing) contains a large amount of fuel from the lower port 13. The same is true in that the intake air (see arrow B ′ in the figure) is restrained from going straight to the exhaust side. The same applies to the effect that the tumble flow indicated by the arrow C 'wraps the intake air with a large amount of fuel supplied from the lower port 13 from the outside.

  Further, the fuel injection from the fuel injection valve 10 is mainly performed in the intake stroke, and in the operation region where the fuel injection amount is large, the fuel is also injected even in a part of the compression stroke. As shown in FIG. 4, the direction of fuel injection from the fuel injection valve 10 is the umbrella back of the intake valve 5 in the valve-open state in the intake stroke (the surface opposite to the combustion chamber 2 side of the umbrella portion 5a). ). By directing the fuel injection direction toward the back of the intake valve 5 in the valve open state, it is possible to expect an effect of weakening the penetration force of the intake air going straight to the exhaust side.

  Here, the fuel injection direction is directed to the back of the umbrella of the intake valve 5. In addition to the case where the fuel injection center line from the fuel injection valve 10 is directed directly to the back of the intake valve 5, the fuel injection valve This includes the case where the fuel injection center line from 10 bounces back against the inner wall of the partition wall 11 or the intake port 3 and is indirectly directed to the back of the umbrella of the intake valve 5.

  Further, as shown in FIG. 4, the fuel injection direction is preferably directed closer to the fuel injection valve 10 than the valve stem 5 b of the intake valve 5 in the valve open state. If the fuel injection direction is closer to the fuel injection valve 10 than the valve stem 5b, the fuel directed toward the exhaust side space is reduced and the injected fuel is sucked into the intake side due to the effect of the umbrella back set to the intake side. To the side space.

  Furthermore, it is desirable that the fuel injection direction is set so as to avoid the valve stem 5b. In order to avoid the valve stem 5b, the fuel injection direction may be set by dividing the fuel injection direction into a plurality of directions as shown in FIG. That is, in each of the parallel intake valves 5, the fuel may be injected separately on both sides of the valve stem 5b.

  Further, as shown in FIGS. 1B and 3B, a downstream end portion of the partition wall 11 is provided with a guide portion 11 a that bends downward or curves downward. The guide portion 11 a can guide the flow of intake air supplied from the lower port 13 into the combustion chamber 2 downward in the cylinder axis direction of the combustion chamber 2. Thereby, the fuel which goes to the space on the exhaust side can be reduced, and much of the injected fuel can be guided to the space on the intake side.

  Furthermore, in the embodiment shown in FIG. 5, the electric supercharger 15 is provided in the intake passage further upstream than the upstream end portion 11 b of the partition wall 11. The electric supercharger 15 can drive a compressor with electric power supplied from a battery or the like to supercharge intake air. By increasing the pressure of the intake air, it is possible to increase the force that the intake air from the upper port 14 reaches the upper space in the combustion chamber 2 and the exhaust port side space. Further, the tumble flow in the combustion chamber 2 can be strengthened.

  At this time, since the guide member 16 that guides the intake air to the upper port 14 side is provided on the upstream side of the upstream end portion 11b of the partition wall 11, the upper port is more than the force of the intake air supplied from the lower port 13. The momentum of the intake air supplied from 14 can be increased.

DESCRIPTION OF SYMBOLS 1 Engine 2 Combustion chamber 3 Intake port 4 Exhaust port 5 Intake valve 5a Umbrella part 5b Valve stem 6 Exhaust valve 7 Ignition apparatus 7a Electrode 8 Exhaust gas recirculation apparatus 10 Fuel injection valve 11 Partition 11a Induction part 11b Upstream end part 12 Introduction Port 13 Lower port 14 Upper port 15 Electric supercharger 16 Induction member 20 Electronic control unit

Claims (8)

An intake port and an exhaust port connected to the combustion chamber of the engine;
A fuel injection valve disposed in the intake port for injecting fuel;
A partition wall separating the intake port into an upper port and a lower port;
An ignition device for burning the fuel supplied into the combustion chamber;
With
The fuel injection valve is an engine control device disposed in the lower port. The engine control device according to claim 1, wherein a cross-sectional area of the upper port is greater than or equal to a cross-sectional area of the lower port. Intake with a relatively low fuel concentration is supplied from the upper space in the combustion chamber to the exhaust port side space through the upper port to form a tumble flow,
The engine control device according to claim 1 or 2, wherein intake air having a relatively high fuel concentration is supplied to a lower space in the combustion chamber through the lower port. An exhaust gas recirculation device for introducing a part of the exhaust gas discharged from the combustion chamber into the intake air as an exhaust gas recirculation gas;
The engine control apparatus according to any one of claims 1 to 3, wherein an inlet for introducing the exhaust gas recirculation gas into the intake air is provided in the upper port. The engine control device according to claim 4, wherein the fuel injection by the fuel injection valve is performed simultaneously with or after the start of introduction of the exhaust gas recirculation gas from the introduction port. An intake valve that opens and closes an opening of the intake port to the combustion chamber;
The fuel injection from the fuel injection valve includes at least an intake stroke.
The engine control apparatus according to any one of claims 1 to 5, wherein a fuel injection direction from the fuel injection valve is directed toward a back of the intake valve in a valve open state. The engine control device according to claim 6, wherein a fuel injection direction from the fuel injection valve is directed to a side closer to the fuel injection valve than a valve stem of the intake valve in the valve open state. A guide portion is provided at the downstream end of the partition wall,
The engine control device according to claim 1, wherein the guide portion guides a flow of intake air supplied from the lower port into the combustion chamber in a downward direction in a cylinder axis direction of the combustion chamber.

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