JP2008128084A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine in which stable stratified combustion can be achieved. <P>SOLUTION: This internal combustion engine has an operation control means 36 controlling an operation state of the internal combustion engine, by arranging a sub-intake passage 32 and an EGR passage 33 with every cylinder, connecting respective downstream end openings 32a and 33a of the sub-intake passage 32 and the EGR passage 33 toward one side part and the other side part in the crankshaft direction of a combustion chamber 8 of the respective cylinders, communicating mutual upstream end openings 32b of the respective sub-intake passages 32 via a sub-intake collecting pipe 47, connecting an upstream end opening 33b of the EGR passage 33 to an exhaust passage 15 via an EGR collecting pipe 34, and interposing a first EGR control valve 35 on the upstream side of the EGR collecting pipe 34. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention includes a plurality of cylinders, an intake passage communicating with the combustion chamber of each cylinder, a surge tank connected to each intake passage, and a throttle valve for each cylinder disposed in each intake passage. The present invention relates to an internal combustion engine provided.

  In this type of internal combustion engine, from the viewpoint of improving fuel efficiency and purifying exhaust gas, a part of the exhaust gas flowing through the exhaust passage (hereinafter referred to as EGR gas) is recirculated to the intake system to be reburned. The EGR device may be provided.

As an internal combustion engine equipped with such an EGR device, for example, in Patent Document 1, an intake passage is defined as an upper passage and a lower passage, and an air flow passing through a throttle valve in the upper passage is directed to a combustion chamber. The EGR gas flow recirculated from the exhaust passage into the lower passage is caused to flow into the combustion chamber in a reverse tumble manner, and fuel is injected into the air flow to perform stratified combustion. A structure has been proposed.
JP 2004-332591 A

  By the way, when the forward tumble air flow and the reverse tumble EGR gas flow are caused to flow into the combustion chamber as in the conventional internal combustion engine, the air flow and the EGR gas flow collide with each other in the combustion chamber. There is concern that stable stratified combustion is difficult to obtain, and there is room for improvement in reducing pumping loss and improving fuel efficiency.

  The present invention has been made in view of the above-described conventional situation, and an object thereof is to provide an internal combustion engine capable of obtaining stable stratified combustion.

  The invention of claim 1 includes a plurality of cylinders, an intake passage connected to each cylinder, a surge tank connected to each intake passage, and a throttle valve for each cylinder disposed in each intake passage. An auxiliary intake passage and an EGR passage are provided for each of the cylinders, and downstream end openings of the auxiliary intake passage and the EGR passage are arranged at one side in the crankshaft direction of the combustion chamber of each cylinder, Connected toward the other side, the upstream end openings of each of the auxiliary intake passages communicate with each other via the auxiliary intake collecting pipe, and the upstream end opening of the EGR passage is connected to the exhaust passage through the EGR collecting pipe. An operation control means for controlling the operation state of the internal combustion engine is provided by interposing a first EGR control valve upstream of the EGR collecting pipe.

  According to a second aspect of the present invention, in the first aspect, the intake passage causes the intake flow from the intake passage to rotate in the same direction as the auxiliary intake flow from the auxiliary intake passage and the EGR flow from the EGR passage. It is characterized by being formed.

  According to a third aspect of the present invention, in the first aspect, a negative pressure control valve is connected to an air introduction pipe for introducing air into the surge tank, and the operation control means is configured to perform EGR stratified combustion in a low / medium load operation region. The negative pressure control valve and the first EGR control valve are controlled to have a predetermined opening degree.

  Here, in claim 3, to control the negative pressure control valve and the first EGR control valve to have a predetermined opening degree, specifically, for example, the opening degree of the negative pressure control valve and the first EGR control valve is reduced. The case where the control is performed within the range of the opening degree (for example, about 15% of full opening) to the middle opening degree (for example, about 50% of full opening) is included.

  According to a fourth aspect of the present invention, in the first aspect, a venturi portion is interposed in an air introduction pipe for introducing air into the surge tank, the venturi portion is connected to the exhaust passage by an exhaust introduction passage, and the exhaust introduction passage is provided. And the operation control means opens the first and second EGR control valves so that EGR stratified combustion is performed in the medium load operation region.

  Here, in claim 4, the opening of the first and second EGR control valves specifically refers to, for example, controlling the opening degree of the first EGR control valve to an intermediate opening degree and setting the opening degree of the second EGR control valve to The case where the control is performed within the range from the small opening to the medium opening is included.

According to a fifth aspect of the present invention, in the fourth aspect, the operation control means is configured such that the CO ₂ concentration of the EGR flow in the EGR passage is higher than the CO ₂ concentration of the intake flow in the intake passage in the low / medium load operation region. The opening degree of the first and second EGR control valves is controlled to be higher.

  The invention of claim 6 is characterized in that, in claim 4, the operation control means closes the first EGR control valve and opens the second EGR control valve in a high load operation region.

  Here, in claim 6, when the first EGR control valve is closed and the second EGR control valve is opened, specifically, for example, the opening degree of the first EGR control valve is within a range from a fully closed to a small opening degree. In which the opening degree of the second EGR control valve is controlled within a range from a large opening degree (for example, about 80% of full opening) to a full opening.

  A seventh aspect of the present invention provides the warm-up state detection means for detecting the progress state of the warm-up operation of the internal combustion engine according to the first aspect, and connects an air introduction pipe for introducing air into the surge tank. A venturi portion is interposed in the introduction pipe, the venturi portion is connected to the exhaust passage by an exhaust introduction passage, and a second EGR control valve is interposed in the exhaust introduction passage, and the operation control means completes the warm-up operation. Until the opening of the first EGR control valve and the second EGR control valve is controlled so that stratified lean combustion is obtained, and after the warm-up operation is completed, the opening of the first EGR control valve and the second EGR control valve Is controlled so as to obtain EGR stratified theoretical air-fuel ratio combustion.

  Here, in claim 7, until the warm-up operation is completed, the opening degree of the first EGR control valve and the second EGR control valve is controlled so as to obtain stratified lean combustion. Specifically, for example, There is a case where the opening degree of the first EGR control valve is controlled within the range from fully closed to a small opening degree and the opening degree of the second EGR control valve is fully closed so that stratified combustion with an air-fuel ratio of 15.0 or more is achieved. included.

  In addition, after the warm-up operation is completed, the opening degree of the first EGR control valve and the second EGR control valve is controlled so that EGR stratified theoretical air-fuel ratio combustion can be obtained. A predetermined opening based on the throttle valve opening and the air flow rate, for example, the first and second EGR control valve openings are fully closed, and the fuel injection period is set to the signal of the oxygen sensor provided in the exhaust pipe. Based on this, a case where feedback control is performed so that the air-fuel ratio becomes 14.6 is included.

  According to an eighth aspect of the present invention, in the first aspect, one intake valve per cylinder, one intake passage communicating with the combustion chamber opening of the intake valve, and two fuel injection valves disposed in the intake passage It is characterized by having.

  According to a ninth aspect of the present invention, in the eighth aspect, the one of the two fuel injection valves has a low load that injects fuel toward the auxiliary intake flow from the auxiliary intake passage in the low load operation region. The other fuel injection valve is a medium / high load fuel injection valve that injects fuel toward the intake air flow from the intake passage in the middle / high load operation region.

  According to a tenth aspect of the present invention, in the ninth aspect, when viewed from above in the cylinder axial direction, the medium and high load fuel injection valve is substantially at the center of the intake passage so as to inject fuel toward the intake flow from the intake passage. The fuel injection valve for low load is disposed obliquely with respect to the center line so as to inject fuel toward the auxiliary intake flow from the auxiliary intake passage. It is characterized by being.

  An eleventh aspect of the present invention is that, in the eighth aspect, one of the two fuel injection valves is configured such that one of the two fuel injection valves directs fuel toward the auxiliary intake flow from the auxiliary intake passage in the low / medium / high load operation region. It is a fuel injection valve for low, medium and high loads that injects, and the other fuel injection valve is a fuel injection valve for medium and high loads that injects combustion toward the intake air flow from the intake passage in the medium / high load operation region. It is a feature.

  A twelfth aspect of the present invention is that, in the ninth or eleventh aspect, the operation control means opens the first EGR control valve in the low load operation region, and the low load fuel injection valve or the low, medium and high load fuel injection valve. The fuel is injected toward the auxiliary intake flow from the auxiliary intake passage.

  Here, in claim 12, in the low load operation region, to open the first EGR control valve, specifically, for example, the opening degree of the first EGR control valve is set to a small opening degree (for example, about 15% of full opening). To a middle opening (for example, about 50% of full opening).

  According to a thirteenth aspect of the present invention, in the ninth or eleventh aspect, an air introduction pipe for introducing air into the surge tank is connected, a venturi section is interposed in the air introduction pipe, and the venturi section is connected to the exhaust by an exhaust introduction passage. The second EGR control valve is interposed in the exhaust introduction passage, and the operation control means opens the second EGR control valve in the medium and high load operation region and supplies fuel from the medium and high load fuel injection valve. It is characterized by being injected toward the intake air flow from the intake passage.

  In the thirteenth aspect of the present invention, in the middle and high load operation region, the opening of the second EGR control valve specifically refers to, for example, controlling the opening of the second EGR control valve within a range from a small opening to a full opening. Includes cases.

  According to a fourteenth aspect of the present invention, in the eleventh aspect, in the low, medium speed and high load operation region, the operation control means performs the low, medium and high load fuel injection within an intake valve opening period from the end of overlap to the intake valve closing. The fuel is injected from both the valve and the fuel injection valve for medium and high loads.

  The invention of a fifteenth aspect includes the two spark plugs according to the eighth aspect, wherein one of the spark plugs is disposed at a position substantially corresponding to the auxiliary intake flow from the auxiliary intake passage, and the other ignition plug is It is characterized by being arranged at a position substantially corresponding to the EGR flow from the EGR passage.

  According to a sixteenth aspect of the present invention, in the first aspect, at least two intake valves per cylinder arranged in parallel so as to be positioned on one side and the other side in the crankshaft direction of the combustion chamber, and the combustion chamber of each intake valve An intake passage communicating with the opening, and two fuel injection valves disposed in the intake passage, the downstream end opening of the EGR passage is disposed toward the intake valve opening of the other side, The downstream end opening of the auxiliary intake passage is disposed toward the intake valve opening on one side, and one of the two fuel injection valves injects fuel toward the intake flow from the intake passage. The other fuel injection valve is arranged to inject fuel toward the auxiliary intake flow from the auxiliary intake passage.

  The invention of claim 17 is characterized in that, in claim 16, the operation control means injects fuel from the other fuel injection valve in the low load operation region.

  An eighteenth aspect of the invention is characterized in that, in the sixteenth aspect, the operation control means injects fuel from the one and the other fuel injection valves in the middle / high load operation region.

  According to a nineteenth aspect of the present invention, in the sixteenth aspect, in the low-medium-speed / high-load operation region, the operation control means is configured to inject the one and other fuel injections during the intake valve opening period from the end of overlap to the intake valve closing. It is characterized by injecting fuel from a valve.

  According to a twentieth aspect of the present invention, in the sixteenth aspect, the first spark plug disposed substantially at the center of the combustion chamber, and the second spark plug disposed at a position substantially corresponding to the auxiliary intake flow from the auxiliary intake passage. It is characterized by having.

  A twenty-first aspect of the present invention is that, in the sixteenth aspect, the first ignition plug disposed substantially at the center of the combustion chamber, and the second and third ignition disposed on one side and the other side of the combustion chamber in the crankshaft direction. It is characterized by having a plug.

  According to a twenty-second aspect of the present invention, in the twenty-first aspect, the operation control means ignites all the first to third spark plugs in an operation region where the first EGR control valve is open.

  According to a twenty-third aspect of the present invention, in the twenty-first aspect, a venturi portion is interposed in an air introduction pipe for introducing air into the surge tank, the venturi portion is connected to the exhaust passage by an exhaust introduction passage, and the exhaust introduction passage The second EGR control valve is interposed, and the operation control means ignites all of the first to third spark plugs in an operation region where the first and second EGR control valves are open.

  According to a twenty-fourth aspect of the present invention, in the twenty-first aspect, the operation control means delays the ignition timing of the first spark plug from the ignition timing of the second and third spark plugs in a high load operation region. It is said.

  According to a twenty-fifth aspect of the present invention, in the twenty-first aspect, the operation control means stops ignition by the first spark plug and ignites only the second and third spark plugs in a high load operation region. It is said.

  Here, as shown in FIG. 5, the operating range in the present invention is divided into three stages of low, medium and high speeds for the sake of convenience, and the engine load is conveniently reduced to low, medium and high loads. It is defined by dividing into For example, the low / medium load operation range refers to A1 to A3 / B1 to B3 in FIG. 5, the high load operation range refers to C1 to C3, and the low / medium speed / high load operation range refers to Refers to C1 and C2.

  According to the internal combustion engine of the first aspect of the invention, the downstream intake openings of the auxiliary intake passage and the EGR passage provided for each cylinder are connected to one side and the other side in the crankshaft direction of the combustion chamber. The auxiliary intake flow from the auxiliary intake passage and the EGR flow from the EGR passage are arranged side by side in the crankshaft direction and flow into the combustion chamber in the same direction. As a result, an independent laminar forward tumble (longitudinal vortex) flow of the auxiliary intake air flow and the EGR flow can be formed, and stable stratified combustion can be obtained even if the EGR flow rate is increased. As a result, it is possible to increase the EGR rate in the low / medium load operation region, to reduce the pumping loss, and to improve fuel consumption and exhaust gas purification.

  According to the second aspect of the present invention, rotation in the same direction as the auxiliary intake flow from the auxiliary intake passage and the EGR flow from the EGR passage is caused to occur in the intake flow from the intake passage. The flow flows into the combustion chamber as a laminar and independent stratified forward tumble flow, preventing mixing due to collision between the conventional forward and reverse tumbles, and stable stratification even when the EGR flow rate is increased. Combustion can be obtained more reliably.

  In the invention of claim 3, a negative pressure control valve is disposed in the air inlet pipe connected to the surge tank, and the negative pressure control valve and the first EGR control valve are opened from a small opening degree in a low / medium load operation range. Since the control is performed within the range of degrees, combustion by the auxiliary intake flow from the auxiliary intake passage can be secured while increasing the EGR rate in the low / medium load operation region, and stable stratified combustion can be performed. That is, when the intake air amount increases by opening the throttle valve, the negative pressure of the air introduction pipe decreases, and accordingly, the EGR gas amount also decreases, and there is a concern that the EGR rate decreases. In the invention of claim 3, by reducing the negative pressure control valve in a range that does not affect the intake air amount, the negative pressure of the air introduction pipe increases, and as a result, the EGR rate can be improved. The negative pressure control valve functions as a fell-safe valve when the throttle valve fails.

  In the invention of claim 4, the venturi portion interposed in the air introduction pipe is connected to the exhaust passage by the exhaust introduction passage, and the second EGR control valve is provided in the exhaust introduction passage. Since both the second EGR control valves are opened, the pumping loss can be suppressed and the fuel consumption can be improved. In this case, since the amount of fresh air is increased in the medium load operation region than in the low load operation region, stable stratified combustion can be performed even if a large amount of EGR gas flows into the combustion chamber from the intake passage and the EGR passage.

In the invention of claim 5, in the low and medium operation range, first the CO ₂ concentration of the EGR flow to be higher than the CO ₂ concentration of the intake air flow. Thus to control the opening of the 2EGR control valve, Stratified combustion can be reliably performed even in a state where the amount of EGR gas is large.

  In the sixth aspect of the invention, in the high load operation region, the first EGR control valve is closed and the second EGR control valve is opened. Therefore, the controllability at the time of load state transition when the throttle is suddenly closed from the fully opened state. And an excessive EGR rate when the throttle is suddenly closed can be prevented. That is, if the throttle valve is suddenly closed from the fully open state while the first EGR control valve is open, a large amount of EGR gas flows from the EGR passage to the combustion chamber. As a result, there is an excess EGR rate and there is a risk of misfire in some cases. In the invention of claim 6, such misfire due to the excessive EGR rate can be prevented.

  In the invention of claim 7, until the warm-up operation is completed, control is performed so as to obtain EGR stratified lean combustion. Therefore, even in an inactive state where the catalyst is not operating at the time of cold start and cold, the exhaust gas Can improve properties. On the other hand, after completion of the warm-up operation, control is performed so that EGR stratified theoretical air-fuel ratio combustion is obtained, so that the catalyst is activated and exhibits an exhaust gas purification function.

  In the invention of claim 8, since one intake valve and two fuel injection valves are arranged in one intake passage, the combustion efficiency is increased by switching the fuel injection valves in accordance with the low, middle and high load operating ranges. It becomes possible. For example, in the low load operation region, the combustion efficiency of the stratified EGR can be increased by injecting the fuel from one fuel injection valve toward the auxiliary intake flow having a large amount of oxygen. As a result, stratified combustion can be reliably performed while suppressing the generation of CO and HC.

  According to the ninth aspect of the present invention, fuel is injected from one fuel injection valve toward the sub-intake flow in the low load operation region, and fuel is directed from the other fuel injection valve toward the intake flow in the middle / high load operation region. Therefore, the combustion efficiency of the stratified EGR can be increased in all operating regions of low, medium and high loads.

  In the invention of claim 10, the fuel injection valve for medium and high loads is disposed substantially on the center line of the intake passage and substantially parallel to the center line, and the fuel injection valve for low loads is disposed obliquely with respect to the center line. Therefore, the fuel from the low load fuel injection valve can be reliably injected toward the auxiliary intake air flow.

  In the invention of claim 11, one fuel injection valve injects the auxiliary intake flow from the auxiliary intake passage in the low / medium / high load operation region, and the other fuel injection valve in the medium / high load operation region. Since the fuel is injected toward the intake air flow from the intake passage at, the combustion efficiency of the stratified EGR can be enhanced in all the low, medium and high load operating regions.

  In the twelfth aspect of the invention, the first EGR control valve is opened and the fuel is injected from the low-load fuel injection valve or the low-medium / high-load fuel injection valve toward the sub-intake flow in the low-load operation region. Even when a large amount of EGR gas flows into the combustion chamber, stable stratified combustion can be performed while suppressing the generation of CO and HC.

  In the invention of claim 13, in the middle / high load operation region, the second EGR control valve is opened and the fuel from the medium / high load fuel injection valve is injected toward the intake air flow from the intake passage. -The combustion efficiency of stratified EGR in a high-load operation range can be increased.

  In the invention of claim 14, in the low / medium speed / high load operation region, the fuel is injected from both fuel injection valves within the intake valve opening period from the end of the overlap. The required amount of fuel can be injected. That is, if fuel is injected during the overlap period in which the intake / exhaust valve opens in the above operating range, the air-fuel mixture may blow through to the exhaust side. For this reason, by injecting fuel from both fuel injection valves in a short time when the exhaust valve is closed and the intake valve is open, the fuel is carried on the intake flow and flows into the combustion chamber. Thereby, the amount of fuel adhering to the wall surface of the intake passage is reduced, the temperature of the air-fuel mixture in the combustion chamber can be lowered, and the knocking resistance can be improved.

  According to the fifteenth aspect of the present invention, one spark plug is arranged so as to substantially correspond to the auxiliary intake flow in the auxiliary intake passage, and the other ignition plug is arranged so as to substantially correspond to the EGR flow. It is possible to reliably ignite the auxiliary intake flow by the spark plug. Further, during medium load operation, the two tumble mixtures can be reliably ignited by both spark plugs. Furthermore, during high-load operation, both spark plugs can reliably ignite the high EGR tumble in the intake passage and increase the combustion speed.

  In the invention of claim 16, two intake valves and two fuel injection valves are arranged in one intake passage, the downstream end opening of the EGR passage is arranged toward the other intake valve opening, and downstream of the auxiliary intake passage. The end opening is arranged toward the intake valve opening on one side, one fuel injection valve is arranged toward the intake flow from the intake passage, and the other fuel injection valve is directed to the sub intake flow from the sub intake passage. As a result, the auxiliary intake air flow and the EGR flow flow into the combustion chamber from the intake valve openings on the one side and the other side, respectively, and an independent side-by-side forward tumble flow can be formed, thereby achieving stable stratified combustion. This can be done even more reliably.

  In the invention of claim 17, since the fuel is injected from the other fuel injection valve toward the auxiliary intake flow in the low load operation region, the fuel can be injected into the auxiliary intake flow with a large amount of oxygen, Stratified combustion can be performed reliably.

  In the eighteenth aspect of the present invention, fuel is injected from both fuel injection valves in the middle / high load operation region, so that the combustion efficiency of the stratified EGR in the middle / high load operation region can be increased.

  According to the nineteenth aspect of the present invention, during low-medium speed operation and high-load operation, fuel is injected from both fuel injection valves within the intake valve opening period from the end of the overlap, so that the intake valve is in the open period. The required amount of fuel can be injected in a short time.

  According to the twentieth aspect of the present invention, since the first spark plug disposed substantially in the center of the combustion chamber and the second spark plug disposed so as to substantially correspond to the auxiliary intake flow in the auxiliary intake passage are provided, the low load operation is performed. Sometimes, the second intake plug can reliably ignite the auxiliary intake air flow. Also, during medium load operation, the two tumble mixtures can be reliably ignited by the first and second spark plugs, and during high load operation, the high EGR tumble of the intake passage can be ensured by the first and second spark plugs. Can be ignited and the combustion rate can be increased.

  In the invention of claim 21, since the first spark plug disposed substantially in the center of the combustion chamber and the second and third spark plugs disposed on one side and the other side in the crankshaft direction are provided. High EGR tumble during load operation can be reliably ignited and the combustion speed can be increased. Further, the flame propagation distance when the cylinder bore diameter is large can be shortened.

  In the inventions of claims 22 and 23, when the first EGR control valve or the first and second EGR control valves are open, all of the first to third spark plugs are ignited, so that the fuel consumption by EGR combustion is further improved. be able to. Here, the operation without EGR control refers to an operation performed at full load and full throttle from the viewpoint of giving priority to the output performance of the internal combustion engine.

  In the invention of claim 24, in the high load operation region, the ignition timing of the first spark plug is delayed from the ignition timing of the second and third spark plugs, so the combustion speed from ignition to immediately after the top dead center of the piston The knocking resistance in the high load operation region can be improved.

  In the invention of claim 24, since only the second and third spark plugs are ignited in the high load operation region, the combustion speed before the top dead center of the piston can be slowed similarly to the above.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  1 to 4 are views for explaining an internal combustion engine according to a first embodiment of the present invention. FIG. 1 is a schematic configuration diagram of the internal combustion engine, FIGS. 2 and 3 are cross-sectional views of the internal combustion engine, and FIG. FIG. 3 is a plan view of an intake passage of the internal combustion engine.

  In the figure, reference numeral 1 denotes a 4-cycle parallel 4-cylinder internal combustion engine. The internal combustion engine 1 includes a crankcase 3 in which a crankshaft 2 common to each cylinder is accommodated, four cylinder bores (cylinders) 4 a and a crankshaft 2. A cylinder block 4 formed in parallel in the direction is coupled, a cylinder head 5 is coupled to the cylinder block 4, and a head cover 23 is attached to the cylinder head 5.

  Pistons 6 are slidably inserted into the cylinder bores 4 a of the cylinder block 4, and the pistons 6 are connected to the crankshaft 2 via connecting rods 7.

  Combustion recesses 5a are respectively formed in portions of the lower joint surface of the cylinder head 5 facing the cylinder bores 4a, and a space surrounded by the combustion recesses 5a, the cylinder bores 4a, and the top surface 6a of the piston 6 is formed in the combustion chamber 8. It has become.

  One intake valve opening 5b is formed on one side of the combustion recess 5a of the cylinder head 5 with respect to the crankshaft perpendicular direction across the crankshaft 2, and one exhaust opening 5c is formed on the other side.

  The intake valve opening 5b and the exhaust valve opening 5c are provided with an intake valve 9 and an exhaust valve 10 for opening and closing the openings 5b and 5c. The intake valve 9 and the exhaust valve 10 are respectively an intake cam shaft 11 and an exhaust cam shaft. 12 is opened and closed.

  Two spark plugs 13 and 14 are inserted into the cylinder head 5 so as to face the combustion recess 5a. Each of the spark plugs 13 and 14 is disposed on a line parallel to the crankshaft 2 passing through the center of the combustion chamber 8 and on both sides of the combustion recess 5a.

  Each exhaust valve opening 5c is led to one side wall of the cylinder head 5 by an exhaust port 5d. An exhaust pipe 15 is connected to each exhaust port 5d. The downstream end of each exhaust pipe 15 is joined to one exhaust joint pipe 16, and a muffler (not shown) is connected to the downstream end of the exhaust joint pipe 16. A catalyst 17 for purifying exhaust gas is interposed in the middle of the exhaust merging pipe 16.

  Each intake valve opening 5b is led out to the other side wall of the cylinder head 5 by an intake port 5e. An intake pipe 18 is connected to each intake port 5e, and an upstream end portion of each intake pipe 18 is connected to a surge tank 19 common to all cylinders.

  Each intake pipe 18 is provided with a throttle valve 31 for each cylinder. Each throttle valve 31 has a butterfly valve type structure in which a valve plate 31b disposed in each intake pipe 18 is fixed to a common valve shaft 31a disposed so as to penetrate each intake pipe 18. .

  An air introduction pipe 20 for introducing air into the surge tank is connected to the side wall 19 a of the surge tank 19. An air cleaner 21 that filters air is connected to the upstream side of the air introduction pipe 20.

  First and second fuel injection valves 25 and 26 are attached to the intake ports 5e of the cylinder head 5 so as to be positioned at one side and the other side in the crankshaft direction, respectively. The first and second fuel injection valves 25, 26 are arranged such that the injection ports 25 a, 26 a are directed toward the center of the valve back of the intake valve 9.

  The internal combustion engine 1 includes an EGR device 30 that recirculates exhaust gas flowing from the exhaust ports 5d through the exhaust branch pipes 15 through the exhaust merging pipes 16 to the intake system for recombustion.

  The EGR device 30 includes an auxiliary intake passage 32 and an EGR passage 33 provided for each cylinder, an auxiliary intake manifold 47 connected to the upstream end opening 32b of each auxiliary intake passage 32, and the EGR passages. 33, an EGR collecting pipe 34 connected to the upstream end opening 33b, a low / medium load first EGR control valve 35 interposed in the middle of the collecting passage 39 assembled by the EGR collecting pipe 34, the internal combustion engine An ECU (operation control means) 36 that controls the operation state of the engine 1 in accordance with each operation region (see FIG. 5) is provided.

  The auxiliary intake passage 32 and the EGR passage 33 are arranged so as to extend substantially in parallel with the intake pipes 18 and have the following structure in detail.

  An EGR inlet 5f and a sub-intake inlet 5f 'are formed on the bottom wall of each intake port 5e of the cylinder head 5. The inflow ports 5f and 5f ′ are arranged in parallel so as to face the left side (one side part) and the right side (other side part) of the combustion chamber 8 of each cylinder in a plan view (see FIG. 4). When viewed from the crankshaft direction, it is formed so as to be directed substantially to the center of the intake valve opening 5b of the intake port 5e (see FIG. 3).

  A downstream end opening 33a of the EGR passage 33 is connected to the EGR inlet 5f, and a flow end opening 32a of the auxiliary intake passage 32 is connected to the auxiliary intake inlet 5f ′.

  As shown in FIG. 3, the auxiliary intake flow a from the auxiliary intake passage 32 descends along the exhaust side wall of the cylinder bore 4a in the combustion chamber 8 from the auxiliary intake inlet 5f 'through the intake valve opening 5b. Then, a forward tumble (vertical vortex) a ′ that reverses at the piston top surface 6a and rises along the intake side wall is generated. Similarly, the EGR flow b from the EGR passage 33 is forward tumble (longitudinal vortex) b ′ in the same direction as the auxiliary intake flow a in the combustion chamber 8 from the EGR inlet 5f through the intake valve opening 5b. Is generated. Further, the intake flow c from the intake pipe 18 passes through the intake valve opening 5b from the intake port 5e, and in the combustion chamber 8, a forward tumble (vertical vortex) c 'in the same direction as the auxiliary intake flow a and the EGR flow b. Is generated. These three forward tumbles a ′, b ′ and c ′ are arranged side by side in the crankshaft direction.

  The auxiliary intake manifold 47 has branch pipes 47a that are arranged substantially parallel to the crankshaft 2 and are formed at predetermined intervals in the longitudinal direction. The auxiliary intake passages 32 are provided in the branch pipes 47a. The upstream end opening 32b is connected.

  Connected to the auxiliary intake manifold 47 is a blow-by gas reduction hose 29 that is an aggregate passage of the auxiliary intake passages 32. The blow-by gas reduction hose 29 is connected so as to communicate with the crankcase 3, and reduces blow-by gas such as air-fuel mixture and combustion gas that has entered the crankcase 3 from the combustion chamber 8 to the combustion chamber 8. A PCV valve 28 is interposed in the middle of the blow-by gas reduction hose 27.

  When the pressure in the crankcase 3 increases due to the lowering of the piston 6 and the intake port 5 e becomes negative, the PCV valve 28 opens, and the blow-by gas in the crankcase 3 collects the auxiliary intake air via the blow-by reduction hose 29. The pipe 47 passes through the auxiliary intake passages 32 to become the auxiliary intake flow a and flows into the combustion chamber 8. Thereby, outward discharge of blow-by gas is prevented.

  The EGR collecting pipe 34 is arranged substantially parallel to the crankshaft 2 and has branch pipes 34a formed at predetermined intervals in the longitudinal direction. The branch pipes 34a are provided upstream of the EGR passages 33. The end opening 33b is connected in communication.

  A downstream end opening of an EGR reduction pipe (collection passage) 39 is connected to the central portion in the longitudinal direction of the EGR collection pipe 34, and the upstream end opening of the EGR reduction pipe 39 is upstream of the catalyst 17 of the exhaust gas merging pipe 16. Connected to the side. Note that the upstream end opening of the EGR reduction pipe 39 may be connected to the downstream side of the catalyst 17 of the exhaust merging pipe 16. The EGR reduction pipe 39 is provided with an EGR cooler 40 for cooling the EGR gas.

  The first EGR control valve 35 for opening and closing the EGR reduction pipe 39 is interposed in the vicinity of the EGR collection pipe 34 upstream of the EGR reduction pipe 39. The first EGR control valve 35 is a step motor type and is controlled to be opened and closed by the ECU 36.

  A negative pressure control valve 22 is disposed in the air introduction pipe 20. The negative pressure control valve 22 is a butterfly valve type in which a valve plate 22 b is fixed to a valve shaft 22 a that is pivotally supported by an air introduction pipe 20. A motor 38 that opens and closes the negative pressure control valve 22 is connected to the outer end of the valve shaft 22a. The motor 38 is controlled by the ECU 36.

  Between the negative pressure control valve 22 and the surge tank 19 of the air introduction pipe 20, a venturi portion 41 is provided that generates a negative pressure by reducing the passage area of the air introduction pipe 20. A reed valve 44 and a second EGR control valve 43 are connected to the venturi section 41, and a downstream end opening 42 a of the exhaust introduction pipe 42 is connected to the second EGR control valve 43. An upstream end opening 42 b of the exhaust introduction pipe 42 is connected in communication between the first EGR control valve 35 and the EGR cooler 40 of the EGR reduction pipe 39.

  The second EGR control valve 43 is a step motor type and is controlled to be opened and closed by the ECU 36. The reed valve 44 allows the exhaust gas to flow from the second EGR control valve 43 side into the air introduction pipe 20 and prevents air from flowing from the air introduction pipe 20 side to the EGR control valve 43 side.

  The first EGR control valve 35 and the second EGR control valve 43 are arranged with their axes directed in the cylinder axial direction (vertical direction) as shown in FIG. 2, but FIG. For ease of illustration, the axis is shown in a different horizontal direction.

  The first fuel injection valve 25 is a low-load fuel injection valve that injects fuel toward the sub-intake flow a from the sub-intake passage 32 in the low-load operation region, and the second fuel injection valve 26 is This is a medium / high load fuel injection valve that injects fuel toward the intake air flow c from the intake pipe 18 in a medium / high load operation region.

  When viewed from above in the cylinder axial direction, the second fuel injection valve 26 is on the center line A of the intake pipe 18 and the center line A so as to inject fuel toward the intake flow c from the intake pipe 18. Are arranged substantially in parallel. The first fuel injection valve 25 is disposed so as to be inclined obliquely inward with respect to the center line A so as to inject fuel toward the auxiliary intake air flow a from the auxiliary intake passage 32 (see FIG. 4). .

  Of the two spark plugs 13, 14, the right spark plug 13 is disposed at a position substantially corresponding to the auxiliary intake air flow a from the auxiliary intake passage 32, and the left ignition plug 14 extends from the EGR passage 33. Are arranged at positions substantially corresponding to the EGR flow b. The spark plugs 13 and 14 are disposed at positions substantially corresponding to the right and left portions in the crankshaft direction of the intake air flow c from the intake pipe 18.

  Based on various parameters such as engine speed, throttle opening, engine temperature, oxygen concentration of exhaust gas, etc., the ECU 36 determines whether the operating state of the internal combustion engine 1 is in the operating ranges A1 to A3, B1 shown in FIG. To B3, C1 to C3, the fuel injection amounts and injection timings of the first and second fuel injection valves 25 and 26, and the ignition timings of the spark plugs 13 and 14 according to the operating range And the open / close control of the negative pressure control valve 22 and the first and second EGR control valves 35 and 43.

  The ECU 36 closes the second EGR control valve 43 and opens the first EGR control valve 35 to inject fuel from the first fuel injection valve 25 in the low load operation region.

  As a result, EGR gas flows into the combustion chamber 8 through the EGR passage 33, blow-by gas flows into the combustion chamber 8 through the auxiliary intake passage 32, and the first fuel injection valve 25 takes the auxiliary intake air into the combustion chamber 8. The fuel is injected toward the sub intake air flow a from the passage 32, and a mixed air flow of the injected fuel and the sub intake air flow a is ignited by the right spark plug 13.

  The ECU 36 controls the opening degree of the first EGR control 35 to an intermediate opening degree and controls the opening degree of the second EGR control valve 43 within a range from a small opening degree to an intermediate opening degree in an intermediate load operation range. Then, fuel is injected from the second fuel injection valve 26.

  As a result, EGR gas flows into the combustion chamber 8 through the EGR passage 33, and EGR gas that has passed through the exhaust introduction pipe 42 flows into the combustion chamber 8 from the surge tank 19 and each intake pipe 18 together with the air. Fuel is injected from the second fuel injection valve 26 toward the intake flow c from 18, and the intake flow c flowing into the combustion chamber 8 is ignited by both spark plugs 13 and 14.

  The ECU 36 controls the opening degree of the first EGR control valve 35 within the range from fully closed to small opening degree, and controls the second EGR control valve 43 within the range from large opening degree to fully opened, in the high load operation range. Then, fuel is injected from the second fuel injection valve 26.

  As a result, the EGR gas that has passed through the exhaust introduction pipe 42 flows into the combustion chamber 8 from the surge tank 19 and each intake pipe 18 together with air, and the fuel from the second fuel injection valve 26 toward the intake flow c from the intake pipe 18. Is injected and the intake flow c flowing into the combustion chamber 8 is ignited by both spark plugs 13 and 14.

  In the low / medium load operation range, the ECU 36 closes the negative pressure control valve 22 to a predetermined opening according to the intake air amount and opens the first EGR control valve 35. For example, the opening degree of the negative pressure control valve 22 and the first EGR control valve 35 is controlled within a range from a small opening degree to a middle opening degree.

The ECU 36 controls the first and second EGR controls so that the CO ₂ concentration of the EGR flow in the EGR passage 33 is higher than the CO ₂ concentration of the intake flow in the intake pipe 18 in the low / medium load operation range. The valves 35 and 43 are controlled to open and close.

  Furthermore, the ECU 36 detects the first EGR control valve 35 until the warm-up operation is completed based on detection from a temperature sensor (warm-up state detection means) that detects the progress state of the warm-up operation of the internal combustion engine 1. And the opening degree of the second EGR control valve 43 is controlled so that EGR stratified lean combustion is obtained, and after the warm-up operation is completed, the opening degree of the first EGR control valve 35 and the second EGR control valve 43 is changed to the EGR stratification theory. Control is performed to obtain air-fuel ratio combustion.

  In the low / medium speed / high load operation region, the ECU 36 performs the first and second fuels within the intake valve opening period after the overlap period in which both the intake valve 9 and the exhaust valve 10 are opened until the intake valve 9 is closed. Fuel is injected from both injection valves 25 and 26.

  As described above, according to the first embodiment, the downstream end openings 32a and 33a of the auxiliary intake passage 32 and the EGR passage 33 provided for each cylinder are parallel to the right side and the left side in the crankshaft direction of the combustion chamber 8. Since it is disposed, the auxiliary intake air flow a from the auxiliary intake air passage 32 and the EGR flow b from the EGR passage 33 flow into the combustion chamber 8 side by side in the same direction in the crankshaft direction. It becomes. As a result, independent stratified forward tumble flows a ′ and b ′ of the auxiliary intake air flow a and the EGR flow b can be formed, and stable stratified combustion can be obtained. As a result, it is possible to increase the EGR rate due to stratified combustion in the low / medium load operation region, to reduce the pumping loss, and to improve the fuel consumption and exhaust gas properties.

  In the present embodiment, rotation in the same direction as the auxiliary intake flow a from the auxiliary intake passage 32 and the EGR flow b from the EGR passage 33 is caused to occur in the intake flow c from the intake pipe 18. The a, EGR flow b, and the intake flow c flow into the combustion chamber 8 so as to form independent layered forward tumbles a ′, b ′, c ′. As a result, it is possible to prevent the mixing due to the collision between the conventional forward tumble and the reverse tumble, and to obtain stable stratified combustion more reliably.

  In the present embodiment, in the low load operation region, the second EGR control valve 43 is closed and the first EGR control valve 35 is opened. Therefore, while increasing the EGR rate in the low load operation region, Combustion by the auxiliary intake air flow a can be performed reliably.

  In this embodiment, a venturi portion 41 is provided in the air introduction pipe 20 connected to the surge tank 19, an exhaust introduction pipe 42 is communicated with the venturi section 41, and a second EGR control valve 43 is provided in the exhaust introduction pipe 42. In the middle load operation range, since both the first and second EGR control valves 35 and 43 are opened, a large amount of EGR gas can flow into the combustion chamber 8 from the intake pipe 18 and the EGR passage 33. Pumping loss can be suppressed to improve fuel efficiency.

  In the present embodiment, the negative pressure control valve 22 is disposed in the air introduction pipe 20, and in the low / medium load operation region, the negative pressure control valve 22 is closed to an opening that does not affect the intake air amount, and the first EGR control is performed. Since the valve is opened, combustion by the auxiliary intake air flow b from the auxiliary intake passage 32 can be secured while increasing the EGR rate in the low / medium load operation region, and stable stratified combustion can be performed. . That is, if the intake air amount increases by opening the throttle valve 31, the negative pressure of the air introduction pipe 20 decreases, and accordingly, the EGR gas amount also decreases, and there is a concern that the EGR rate decreases. By setting the opening of the negative pressure control valve 22 so as not to affect the intake air amount, the negative pressure of the air introduction pipe 20 is increased, and the tumble strength can be increased.

  Further, when the throttle valve 31 breaks down and becomes defective in return, the negative pressure control valve 22 functions as a fell-safe valve by controlling the opening of the negative pressure control valve 22 according to the throttle operation amount. To do.

In the present embodiment, in the low / medium operation range, the first and second EGR control valves 35, the CO ₂ concentration of the EGR flow in the EGR passage 33 are higher than the CO ₂ concentration of the intake flow in the intake pipe 18. Since the opening degree 43 is controlled, stratified combustion can be reliably performed even in a state where the amount of EGR gas is large.

  In the present embodiment, since the first EGR control valve 35 is closed and the second EGR control valve 43 is opened in the high load operation region, the control at the time of load state transition when the throttle valve 22 is suddenly closed from the fully open state is performed. Therefore, an excessive EGR rate can be prevented when the throttle is suddenly closed. That is, when the throttle valve 22 is suddenly closed from the fully opened state while the first EGR control valve 35 is open, a large amount of EGR gas flows into the combustion chamber 8 from the EGR passage 33. As a result, there is an excess EGR rate and there is a risk of misfire in some cases.

  In the present embodiment, control is performed so that EGR stratified lean combustion is obtained until the warm-up operation is completed. Therefore, the emission is reduced even in an inactive state where the catalyst 17 is not operating during cold start and cold. be able to. On the other hand, after completion of the warm-up operation, control is performed so that EGR stratified stoichiometric combustion is obtained, so that the catalyst 17 is activated and exhibits an exhaust gas purification function.

  In the present embodiment, since one intake valve 9 and two first and second fuel injection valves 25 and 26 are arranged in one intake port 5e, the fuel injection valve according to the low / medium / high load operating range. By switching between 25 and 26, the combustion efficiency can be increased. That is, in the low load operation region, the combustion efficiency of the stratified EGR can be increased by injecting and supplying the fuel from the first fuel injection valve 25 toward the auxiliary intake air flow a having a large amount of oxygen. As a result, stratified combustion can be reliably performed while suppressing the generation of CO and HC.

  In the present embodiment, fuel is injected from the first fuel injection valve 25 toward the sub intake air flow a in the low load operation region, and fuel is injected from the second fuel charge injection valve 26 in the middle / high load operation region. Since the injection is supplied toward c, the combustion efficiency can be improved in the entire operation range of low, medium and high loads.

  In the present embodiment, the second fuel injection valve 26 is disposed on the center line A of the intake pipe 18 and substantially parallel to the center line A, and the first fuel injection valve 25 is disposed with respect to the center line A. Therefore, the fuel from the first fuel injection valve 25 at the time of low load operation can be reliably injected and supplied toward the auxiliary intake air flow a, and the second fuel injection at the time of medium / high load operation The fuel from the valve 26 can be reliably injected and supplied toward the intake air flow c.

  In the present embodiment, in the high load operation region, the second EGR control valve 43 is opened and the fuel from the second fuel injection valve 26 is injected toward the intake flow c. The combustion efficiency of the stratified EGR can be increased.

  In the present embodiment, in the low / medium speed operation and high load operation regions, the fuel from both the first and second fuel injection valves 25 and 26 is within the intake valve opening period from the end of overlap until the intake valve 9 is closed. Therefore, the required amount of fuel can be injected in a short time when the intake valve 9 is open. That is, if fuel is injected during the overlap period in which both the intake and exhaust valves 9 and 10 are open in the above operating range, the air-fuel mixture may blow through to the exhaust port side. For this reason, by injecting fuel from both the fuel injection valves 25 and 26 in a short time when the intake valve 9 is opened after the overlap is completed, the fuel is carried on the intake flow c and smoothly flows into the combustion chamber 8. It becomes. Thereby, the amount of fuel adhering to the wall surface of the intake port 5e is reduced, the temperature of the air-fuel mixture in the combustion chamber 8 can be lowered, and the knocking resistance can be improved.

  In the present embodiment, one spark plug 13 is arranged so as to substantially correspond to the auxiliary intake flow a from the auxiliary intake passage 32, and the other ignition plug 14 is arranged to substantially correspond to the EGR flow b from the EGR passage 33. Therefore, the auxiliary intake air flow a can be reliably ignited by one spark plug 13 during low load operation, and the two tumble mixtures can be reliably ignited by both spark plugs 13 and 14 during medium load operation. In addition, during high load operation, both spark plugs 13 and 14 can reliably ignite high EGR tumble and increase the combustion speed after the middle combustion stage.

  In the above embodiment, the second fuel injection valve 26 is disposed on the center line A of the intake pipe 18 and parallel to the center line A, and the first fuel injection valve 25 is disposed obliquely with respect to the center line A. In the present invention, as shown in FIG. 6, the first and second fuel injection valves 25 and 26 are arranged on one side and the other side in the crankshaft direction with the center line A of the intake pipe 18 in between. You may arrange | position substantially parallel to this centerline A. FIG.

  When the fuel injection valves are arranged in this manner, the first fuel injection valve 25 is used as an intermediate / high load operation region injection valve, and the second fuel injection valve 26 is used as a low / medium / high load transfer region injection valve. By doing so, the combustion efficiency of the stratified EGR can be increased in the entire operation region.

  In the above embodiment, the case where the blow-by gas reduction hose 29 for reducing blow-by gas is connected to the auxiliary intake manifold 47 connected to each auxiliary intake passage 32 has been described. However, the connection passage to the auxiliary intake passage in the present invention Is not limited to this. For example, a canister purge hose for purging fuel evaporative gas generated in the fuel tank may be connected via an on-off valve. In addition, a brake booster that reduces the brake pedal force may be connected.

  In the present invention, the first fuel injection valve 25 is injected toward the auxiliary intake air flow a in the low / medium / high load operation region, and the second fuel injection valve 26 is injected into the intake air flow in the medium / high load operation region. You may make it inject toward c. In this case, the combustion efficiency of the stratified EGR can be increased in the entire operation region.

  Furthermore, in the present invention, during the low load operation, the first EGR control valve 35 is opened and fuel is injected from both the first and second fuel injection valves 25 and 26 toward the sub intake air flow a. May be. In this case, even when a large amount of EGR gas flows into the combustion chamber 8, stable stratified combustion can be performed while suppressing generation of CO and HC.

  FIG. 7 is a view for explaining an internal combustion engine according to the second embodiment of the present invention. In the figure, the same reference numerals as those in FIGS. 1 and 2 denote the same or corresponding parts.

  The internal combustion engine 1 of the second embodiment includes two intake valves 9 and 9 'and an exhaust valve 10 on one side (lower side in the drawing) and the other side (upper side in the drawing) arranged in parallel in two crankshaft directions for each cylinder. 10 ', branched intake ports 5e, 5e branched from one intake port to the combustion chamber 8 of each intake valve 9, 9' and communicated, and two first and second intake ports disposed in the intake port 5e. Fuel injection valves 25 and 26 are provided.

  In the present embodiment, the downstream end opening 32a of the auxiliary intake passage 32 is disposed toward the intake valve opening 5b of the intake valve 9 on one side, and the downstream end opening 33a of the EGR passage 33 is formed on the intake air on the other side. The valve 9 'is disposed toward the intake valve opening 5b'.

  The first fuel injection valve 25 is arranged to inject fuel toward the intake air flow from the intake pipe 8, and the second fuel injection valve 26 is directed to the auxiliary intake air flow from the auxiliary intake passage 32. It is arranged to inject fuel.

  The internal combustion engine 1 includes a first spark plug 50 disposed substantially at the center of the combustion chamber 8 and a line disposed on the side of the combustion chamber on a line parallel to the crankshaft 2 passing through the center of the combustion chamber 8. Side and other side second and third spark plugs 51 and 52 are provided.

  The ECU 36 injects fuel from the second fuel injection valve 26 toward the auxiliary intake air flow a in the low load operation region, and both the first and second fuel injection valves 25, 25 in the middle and high load operation regions. The fuel is injected from 26 toward the intake air flow c.

  In the low / medium speed / high load operation range, the ECU 36 has both the first and second fuel injection valves 25 and 26 within the intake valve opening period after the overlap period ends until the intake valves 9 and 9 'are closed. The fuel is injected from.

  The ECU 36 ignites all of the first to third spark plugs 50 to 52 in the operating range in which the first EGR control valve 35 is open, or in the operating range in which both the first and second EGR control valves 35 and 43 are open. Let

  In the high load operation region, the ignition timing of the first spark plug 50 is delayed from the ignition timing of the second and third spark plugs 51 and 52, or the ignition by the first spark plug 50 is stopped and the second Only the third spark plugs 51 and 52 are ignited.

  In the second embodiment, two intake valves 9, 9 'and two first and second fuel injection valves 25, 26 are arranged in branch intake ports 5e, 5e branched from one intake port, and an EGR passage 33 is provided. The downstream end opening 33a is disposed toward the other intake valve opening 5b ', the downstream end opening 32a of the auxiliary intake passage 32 is disposed toward the one intake valve opening 5b, and the first fuel injection valve 25 is disposed. Since the second fuel injection valve 26 is arranged toward the auxiliary intake flow a from the auxiliary intake passage 32, the auxiliary intake flow a and the EGR flow b are equal to each other. Since it flows into the combustion chamber 8 from the intake valve openings 5b, 5b 'on the side and the other side, independent side-by-side forward tumble flows can be formed, and stable stratified combustion can be performed more reliably. .

  In the present embodiment, since the fuel is injected from the second fuel injection valve 26 toward the auxiliary intake flow a in the low load operation region, the fuel can be injected into the auxiliary intake flow a having a large amount of oxygen. Thus, stratified combustion can be performed reliably.

  In the present embodiment, since the fuel is injected from both the first and second fuel injection valves 25 and 26 in the middle / high load operation region, the combustion efficiency of the stratified EGR in the middle / high load operation region is increased. Can be increased.

  In the present embodiment, during low and medium speed operation and high load operation, fuel is injected from both fuel injection valves 25 and 26 within the intake valve opening period from the end of the overlap period until the intake valves 9 and 9 'are closed. As a result, the required amount of fuel can be injected in a short time during the opening period of the intake valves 9, 9 '.

  In the present embodiment, a first spark plug 50 disposed substantially at the center of the combustion chamber 8, and second and third spark plugs 51 and 52 disposed on the crankshaft axis and at the peripheral edge of the combustion chamber 8 are provided. Therefore, high EGR tumble during high load operation can be reliably ignited and the combustion speed can be increased. Further, the flame propagation distance when the cylinder bore diameter is large can be shortened.

  In the present embodiment, when the first and second EGR control valves 35 and 43 are open, all of the first to third spark plugs 50 to 52 are ignited, so that the fuel consumption due to stratified combustion can be further improved. . Here, the operation without EGR control refers to an operation performed at full load and full throttle from the viewpoint of giving priority to the output performance of the internal combustion engine.

  In the present embodiment, in the high load operation region, the ignition timing of the first spark plug 50 is delayed from the ignition timing of the second and third spark plugs 51 and 52 or the second and third spark plugs 51 and 52. Since only the ignition is performed, the combustion speed in the initial stage of combustion can be slowed down, and the knocking resistance in the high load operation region can be improved.

  In the second embodiment, the case where the first to third spark plugs 50 to 52 are provided has been described. However, the present invention relates to the first spark plug disposed in the substantially central portion of the combustion chamber, and the auxiliary intake air. You may provide the 2nd spark plug arrange | positioned in the position substantially corresponding to the sub intake air flow from a channel | path. In this case, the secondary intake plug can reliably ignite the secondary intake air flow during low load operation, and the two tumble mixtures can be reliably ignited by the first and second spark plugs during medium load operation. Further, during high load operation, the first and second spark plugs can reliably ignite the high EGR tumble in the intake passage, and the combustion speed at the initial stage of combustion can be increased.

1 is a schematic configuration diagram of an internal combustion engine according to a first embodiment of the present invention. It is sectional drawing of the said internal combustion engine. It is sectional drawing of the said internal combustion engine. It is a top view of the intake passage of the internal combustion engine. It is a top view of the intake passage by the modification of the said embodiment. It is a figure which shows the modification of the said embodiment. It is a schematic block diagram of the internal combustion engine by 2nd Embodiment of this invention.

Explanation of symbols

1 Internal combustion engine 2 Crankshaft 4a Cylinder bore (cylinder)
5b, 5b 'intake valve opening 5e intake port (intake passage)
8 Combustion chamber 9, 9 'Intake valve 13, 14, 50-52 Spark plug 17 Catalyst 18 Intake pipe (intake passage)
19 Surge tank 20 Air introduction pipe 22 Negative pressure control valve 25, 26 Fuel injection valve 31 Throttle valve 32 Sub intake passage 32a Downstream end opening 32b Upstream end opening 33 EGR passage 33a Downstream end opening 33b Upstream end opening 34 EGR collecting pipe 35 First 1 EGR control valve 36 ECU (operation control means, warm-up state detection means)
41 Venturi section 42 Exhaust introduction pipe (exhaust introduction passage)
43 Second EGR control valve 47 Auxiliary intake manifold A A Intake passage center line a Auxiliary intake flow b EGR flow c Intake flow a ', b', c 'forward tumble flow

Claims (25)

An internal combustion engine comprising a plurality of cylinders, an intake passage connected to each cylinder, a surge tank connected to each intake passage, and a throttle valve for each cylinder disposed in each intake passage. And
An auxiliary intake passage and an EGR passage are provided for each cylinder,
The respective downstream end openings of the auxiliary intake passage and the EGR passage are connected to one side and the other side in the crankshaft direction of the combustion chamber of each cylinder,
The upstream end openings of each auxiliary intake passage are communicated with each other,
The upstream end opening of the EGR passage is connected to the exhaust passage by a collection passage, and a first EGR control valve is interposed in the middle of the collection passage,
An internal combustion engine comprising operation control means for controlling an operation state of the internal combustion engine. 2. The intake passage according to claim 1, wherein the intake passage is formed to cause rotation in the same direction as the auxiliary intake flow from the auxiliary intake passage and the EGR flow from the EGR passage in the intake flow from the intake passage. An internal combustion engine. 2. The negative pressure control valve according to claim 1, wherein a negative pressure control valve is connected to an air introduction pipe for introducing air into the surge tank, and the operation control means is configured to perform EGR stratified combustion in a low / medium load operation region. And an internal combustion engine that controls the first EGR control valve to a predetermined opening degree. 2. The venturi portion according to claim 1, wherein a venturi portion is interposed in an air introduction pipe for introducing air into the surge tank, the venturi portion is connected to the exhaust passage by an exhaust introduction passage, and a second EGR control valve is interposed in the exhaust introduction passage. Let
The internal combustion engine characterized in that the operation control means opens the first and second EGR control valves so that EGR stratified combustion is performed in a medium load operation region (full open or large opening). 5. The operation control means according to claim 4, wherein, in the low / medium load operation region, the first control unit is configured such that the CO ₂ concentration of the EGR flow in the EGR passage is higher than the CO ₂ concentration of the intake flow in the intake passage. An internal combustion engine that controls the opening degree of the second EGR control valve. In the fourth aspect of the present invention, the operation control means closes the first EGR control valve (fully closes or opens a small opening) and opens the second EGR control valve (full open or large opening) in a high load operation region. An internal combustion engine characterized by that. In Claim 1, provided with a warm-up state detection means for detecting the progress state of the warm-up operation of the internal combustion engine,
An air introduction pipe for introducing air into the surge tank is connected, a venturi portion is interposed in the air introduction pipe, the venturi portion is connected to the exhaust passage by an exhaust introduction passage, and a second EGR control is provided in the exhaust introduction passage. Through the valve,
The operation control means controls the opening degrees of the first EGR control valve and the second EGR control valve so that stratified lean combustion is obtained until the warm-up operation is completed. An internal combustion engine that controls the opening degree of the first EGR control valve and the second EGR control valve so as to obtain EGR stratified stoichiometric combustion. In Claim 1, it is provided with one intake valve for each cylinder, one intake passage connected to the combustion chamber opening of the intake valve, and two fuel injection valves arranged in the intake passage. A characteristic internal combustion engine. The fuel injection valve according to claim 8, wherein one of the two fuel injection valves is a low-load fuel injection valve that injects fuel toward the auxiliary intake flow from the auxiliary intake passage in a low-load operation region. The other fuel injection valve is a medium / high load fuel injection valve that injects fuel toward the intake air flow from the intake passage in a middle / high load operation region. The fuel injection valve for medium and high loads according to claim 9, wherein when viewed from above in the cylinder axial direction, the fuel injection valve for medium and high loads is on a substantially center line of the intake passage so as to inject fuel toward the intake air flow from the intake passage. The internal combustion engine characterized in that the low-load fuel injection valve is disposed substantially in parallel, and is disposed obliquely with respect to the center line so as to inject fuel toward the auxiliary intake flow from the auxiliary intake passage. organ. 9. The low-medium / high-load fuel according to claim 8, wherein one of the two fuel injection valves injects fuel toward the sub-intake flow from the sub-intake passage in the low / medium / high load operation region. An internal combustion engine that is an injection valve, and the other fuel injection valve is a medium-high load fuel injection valve that injects combustion toward the intake air flow from the intake passage in a medium-high load operation region. 12. The operation control means according to claim 9, wherein the operation control means opens the first EGR control valve in the low load operation region (fully opened or has a large opening), and the low load fuel injection valve or the low, medium and high load fuel injection. An internal combustion engine in which fuel is injected from a valve toward a sub-intake flow from the sub-intake passage. In Claim 9 or 11, an air introduction pipe for introducing air to the surge tank is connected, a venturi is interposed in the air introduction pipe, the venturi is connected to the exhaust passage by an exhaust introduction passage, and A second EGR control valve is interposed in the exhaust introduction passage,
The operation control means opens the second EGR control valve (fully opened or has a large opening) in the medium and high load operation region, and injects fuel from the medium and high load fuel injection valve toward the intake flow from the intake passage. An internal combustion engine characterized in that 12. The low / medium / high load operation region according to claim 11, wherein the low / medium / high load operation region includes the low / medium / high load fuel injection valve and the medium / high load fuel injection during the intake valve opening period from the end of overlap to the intake valve closing. An internal combustion engine in which fuel is injected from both valves. In claim 8, two spark plugs are provided, one of the spark plugs is disposed at a position substantially corresponding to the auxiliary intake flow from the auxiliary intake passage, and the other spark plug is connected to the EGR flow from the EGR passage. An internal combustion engine characterized by being disposed at a substantially corresponding position. 2. The intake air according to claim 1, wherein at least two intake valves are arranged in parallel so as to be located on one side and the other side in the crankshaft direction of the combustion chamber, and one intake air communicates with the combustion chamber opening of each intake valve. A passage and two fuel injection valves disposed in the intake passage,
The downstream end opening of the EGR passage is disposed toward the intake valve opening on the other side portion, and the downstream end opening of the auxiliary intake passage is disposed toward the intake valve opening on the one side portion,
Of the two fuel injection valves, one fuel injection valve is arranged to inject fuel toward the intake flow from the intake passage, and the other fuel injection valve is directed to the sub intake flow from the sub intake passage. And an internal combustion engine arranged to inject fuel. The internal combustion engine according to claim 16, wherein the operation control means injects fuel from the other fuel injection valve in a low load operation region. 17. The internal combustion engine according to claim 16, wherein the operation control means injects fuel from the one and the other fuel injection valves in a middle / high load operation region. 17. The operation control means according to claim 16, wherein the operation control means injects fuel from the one and the other fuel injection valves within an intake valve opening period from the end of overlap to the intake valve closing in a low / medium speed / high load operation region. An internal combustion engine characterized by the above. 17. The method according to claim 16, further comprising: a first spark plug disposed substantially at the center of the combustion chamber; and a second spark plug disposed at a position substantially corresponding to the auxiliary intake flow from the auxiliary intake passage. An internal combustion engine. In Claim 16, the 1st spark plug arrange | positioned in the approximate center of a combustion chamber, and the 2nd, 3rd spark plug arrange | positioned at the crank-axis direction one side part and the other side part of a combustion chamber were provided. A characteristic internal combustion engine. 23. The internal combustion engine according to claim 21, wherein the operation control means ignites all of the first to third spark plugs in an operation region where the first EGR control valve is open. 23. A venturi portion is interposed in an air introduction pipe for introducing air into the surge tank, the venturi portion is connected to the exhaust passage by an exhaust introduction passage, and a second EGR control valve is interposed in the exhaust introduction passage. The operation control means ignites all of the first to third spark plugs in an operation region where the first and second EGR control valves are open. 22. The internal combustion engine according to claim 21, wherein the operation control means delays the ignition timing of the first spark plug from the ignition timing of the second and third spark plugs in a high load operation range. 23. The internal combustion engine according to claim 21, wherein the operation control means stops ignition by the first spark plug and ignites only the second and third spark plugs in a high load operation range.

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