JP2010031688A - Spark-ignition internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spark-ignition internal combustion engine reducing a pumping loss in a part-load operation area. <P>SOLUTION: An external EGR passage 41 is connected to the side downstream of an intake air control valve 20 in the branch pipe 16a of an intake passage 16, and an EGR check valve 46 allowing EGR gas to flow only to the side of a cylinder is provided in the external EGR passage 41. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a spark ignition internal combustion engine in which an intake control valve is disposed in an intake passage communicating with each cylinder, and a bypass passage is provided to bypass the intake control valve.

In an internal combustion engine that operates at a stoichiometric air-fuel ratio (λ = 1), external EGR or internal EGR is used to improve fuel efficiency and reduce NOx, and intake air such as a horizontal vortex (swirl) or a vertical vortex (tumble) It has been proposed to increase the EGR resistance limit by generating eddy currents. For example, in Patent Document 1, an intake control valve is disposed in an intake passage and a bypass passage that bypasses the intake control valve in order to generate a lateral vortex or a vertical vortex intake vortex in a cylinder during partial load operation. Proposed structures have been proposed.
Japanese Patent No. 3559130 (FIG. 4)

  By the way, when the bypass passage for bypassing the intake control valve is provided as in the prior art, in the partial load operation region, the intake pipe is always in a negative pressure state close to the negative pressure at the intake bottom dead center. . For this reason, since the intake valve starts to open, negative pressure acts on the combustion chamber, and there is a concern that the pumping loss increases.

  The present invention has been made in view of the above-described conventional situation, and an object thereof is to provide a spark ignition internal combustion engine that can reduce pumping loss in a partial load operation region.

  According to the first aspect of the present invention, there is provided a plurality of cylinders, an intake passage that includes a branch pipe portion that communicates with each cylinder, an intake manifold portion that collects the branch pipe portions, and one intake pipe disposed in the intake manifold portion. A throttle valve, an intake control valve disposed in each branch pipe, a bypass passage provided to bypass each intake control valve and generating an intake vortex flow in each cylinder, and provided in the bypass passage A spark ignition type internal combustion engine having an intake check valve that allows only an intake flow to the cylinder side, wherein an external EGR passage is connected downstream of the intake control valve of each branch pipe portion. The external EGR passage is provided with an EGR check valve that allows only the flow of EGR gas to the cylinder side.

  According to a second aspect of the present invention, in the spark ignition type internal combustion engine of the first aspect, a surge tank is interposed between the intake manifold portion and the branch pipe portion, and the intake control valve is It is characterized in that it is disposed in the vicinity of the connection portion of the branch pipe portion to the surge tank.

  According to a third aspect of the present invention, in the spark ignition type internal combustion engine according to the first aspect, the external EGR passage is connected to a downstream end portion of the branch pipe portion.

  According to the spark ignition internal combustion engine of the first aspect of the invention, the external EGR passage is connected to the downstream side of the intake control valve of each branch pipe portion of the intake passage, and the check valve is provided in the external EGR passage. For example, the negative pressure in the branch pipe part can be reduced by introducing the EGR gas into the branch pipe part before the start of the intake stroke. As a result, since the intake negative pressure at the start of opening of the intake valve is reduced, the pumping loss can be reduced and the fuel consumption can be improved.

  The EGR gas introduced into the branch pipe portion flows into the cylinder from the entire periphery of the intake opening of the intake valve, whereas fresh air flows into the cylinder from a part of the intake opening from the bypass passage. Therefore, the intake air flow having a high fresh air ratio and the EGR gas are stratified and injected into the cylinder. As a result, flame propagation is performed rapidly, a large amount of EGR can be performed, and the pumping loss can be further reduced.

  In the invention of claim 2, since the intake control valve is disposed at the upstream end portion of the branch pipe portion of the intake passage, the passage volume from the intake control valve to the intake opening can be increased, and a large amount of the internal control valve can be increased. EGR or external EGR can be stored, and in this respect, pumping loss can be further reduced and fuel consumption can be improved.

  In the invention of claim 3, since the external EGR passage is connected to the downstream end portion of the branch pipe portion of the intake passage, the EGR gas can be kept in the vicinity of the intake opening, and the response in the transition period can be improved. That is, when EGR gas is retained in the entire branch pipe portion of the intake passage, even if the accelerator is suddenly opened, the EGR gas flows into the cylinder, so the output does not increase, and therefore the accelerator responsiveness deteriorates.

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

  1 and 2 are diagrams for explaining a spark ignition type internal combustion engine according to an embodiment of the present invention. FIG. 1 is a schematic configuration diagram of the spark ignition type internal combustion engine, and FIG. 2 is a sectional view of the internal combustion engine. is there.

  In the figure, reference numeral 1 denotes a four-cycle multi-cylinder spark ignition internal combustion engine. The internal combustion engine 1 is connected to a cylinder block 2 in which four cylinder bores 2a are formed in parallel, and a cylinder head 3 having combustion recesses 3a formed so as to face the cylinder bores 2a. The piston 5 is slidably inserted into the piston 5 and has a schematic structure in which the piston 5 is connected to the crankshaft 4 via a connecting rod 6. A combustion chamber 7 is formed by a space surrounded by the cylinder bore 2 a, the combustion recess 3 a and the top surface of the piston 4.

  Each combustion recess 3 a of the cylinder head 3 is formed with one intake opening 3 b and one exhaust opening 3 c communicating with the combustion chamber 7. The intake opening 3b and the exhaust opening 3c are arranged on one side and the other side with a straight line c parallel to the crankshaft 4 when viewed in the cylinder axis direction, and face each other with the straight line c in between.

  An intake valve 8 and an exhaust valve 9 are disposed in the intake opening 3b and the exhaust opening 3c, respectively. The intake valve 8 and the exhaust valve 9 are driven to open and close by an intake cam shaft 10 and an exhaust cam shaft 11, respectively.

  Two spark plugs 12 and 12 are mounted on the cylinder head 3 so as to face the combustion recess 3a for each cylinder bore 2a. Each of the spark plugs 12 is disposed so as to be positioned substantially on the straight line c and on both sides of the intake valve 8 and the exhaust valve 9.

  The intake opening 3b is led to one side wall of the cylinder head 3 by an intake port 3d, and the exhaust opening 3c is led to the other side wall of the cylinder head 3 by an exhaust port 3e.

  An exhaust pipe 13 is connected to each exhaust port 3e. One exhaust merging pipe 14 is connected to the downstream end of each exhaust pipe 13, a catalyst 15 for purifying exhaust gas is interposed in the middle of the exhaust merging pipe 14, and a muffler is disposed at the downstream end. (Not shown) is connected.

  An intake passage 16 is connected to the cylinder head 3. The intake passage 16 includes an intake port 3d for each cylinder, a branch pipe portion 16a for each cylinder connected to each intake port 3d, a surge tank 17 to which the four branch pipe portions 16a are connected, And an intake manifold 18 connected to the surge tank 17. An air cleaner 19 is connected to the intake manifold 18.

  One throttle valve 23 is disposed in the vicinity of the connection portion of the intake manifold 18 to the surge tank 17.

  A fuel injection valve 21 is attached to the downstream end of each branch pipe portion 16a so as to be directed to the axial center of the intake port 3d. The fuel injection valve 21 is arranged to inject and supply liquid fuel such as gasoline or gas fuel such as propane toward the center of the back of the intake valve 6.

  An intake control valve 20 is disposed in the vicinity of the connecting portion of each branch pipe portion 16a to the surge tank 17. The intake control valves 20 are connected by a common valve shaft 20a, and are integrally opened and closed by a drive motor 29 connected to the valve shaft 20a.

  Each branch pipe portion 16 a is provided with a bypass passage 36 that bypasses the intake control valve 20. Each of the bypass passages 36 directs and blows out air so that a lateral vortex or vertical vortex intake vortex A is generated in the cylinder bore 2a, and extends along the lower portion of the branch pipe portion 16a. Is formed.

  The downstream end port 36 a of each bypass passage 36 is connected to the vicinity of the intake opening 3 b of the intake port 3 d, and the upstream end port 36 b is connected to the surge tank 17.

  An intake check valve 35 is disposed at the upstream end of each bypass passage 36. The intake check valve 35 allows only the air flow from the surge tank 17 to the cylinder side and prevents the flow in the reverse direction.

  The internal combustion engine 1 includes an EGR device 40 that recirculates a part of the exhaust gas flowing from the exhaust pipes 13 through the exhaust collecting pipes 14 to the combustion chamber 7.

  The EGR device 40 is provided with one EGR introduction pipe (external EGR passage) 41 connected to the upstream side of the catalyst 15 of the exhaust merging pipe 14 and an intermediate portion of the EGR introduction pipe 41 to supply EGR gas. An EGR cooler 42 that cools to a predetermined temperature and an EGR control valve 43 that is interposed downstream of the EGR cooler 42 are provided. Further, a particulate trap 44 for removing particulates such as carbon mixed in the EGR gas is interposed on the upstream side of the EGR cooler 42 of the EGR introduction pipe 41.

  The EGR introduction pipe 41 is connected to the downstream side of the intake control valve 20 of each branch pipe section 16a, and has the following structure in detail.

  An EGR introduction port 41a is formed on the downstream side of the intake control valve 20 of each branch pipe portion 16a, and each EGR introduction port 41a is connected to one EGR distribution pipe 41b. The EGR introduction pipe 41 is connected to the EGR distribution pipe 41b.

  Each EGR introduction port 41a is provided with an EGR check valve 46. The EGR check valve 46 is a reed valve type that allows only the flow of EGR gas to the cylinder side and prevents the flow in the reverse direction.

  The intake control valve 20 and the EGR control valve 43 are controlled to be opened and closed by the ECU 33 according to the operating state of the internal combustion engine 1. For example, the ECU 33 controls the intake control valve 20 to be closed and the EGR control valve 43 to be opened in a partial load operation region during low and medium loads.

  According to the present embodiment, the EGR introduction pipe 41 is connected to the downstream side of the intake control valve 20 of each branch pipe portion 16a, and the EGR check valve 46 is disposed at each EGR introduction port 41a of the EGR introduction pipe 41. By introducing EGR gas into the branch pipe portion 16a before the intake stroke, the negative pressure in the branch pipe portion 16a can be reduced. As a result, since the intake negative pressure at the beginning of opening of the intake valve 8 is reduced, the pumping loss can be reduced and the fuel consumption can be improved.

  The EGR gas introduced into the branch pipe portion 16a flows into the cylinder bore 2a from the entire circumference of the intake opening 3b of the intake valve 8, whereas fresh air passes through the bypass passage 36 and enters the intake opening 3b. Since a part flows into the cylinder bore 2a, the intake air flow A and the EGR gas having a high fresh air ratio are stratified and injected into the cylinder. As a result, flame propagation is performed rapidly, a large amount of EGR can be performed, and the pumping loss can be further reduced.

  In a standard multi-cylinder internal combustion engine, a throttle valve 23 is arranged in the upstream collecting pipe 18 of the branch pipe portion 16b communicating with each cylinder. For this reason, in the partial load operation region, there is always a high negative pressure close to the bottom dead center of the intake stroke in each branch pipe portion 16a, and this high negative pressure acts on the cylinder bore from the beginning of the opening of the intake valve 8. As a result, pumping loss is likely to occur.

  In the present embodiment, the intake control valve 20 is provided in each branch pipe portion 16a, and the intake check valve 35 is provided in the bypass passage 36, so that EGR gas is introduced into the branch pipe portion 16a before the intake stroke. The negative pressure can be reduced. In addition, since the strong intake vortex A is generated in the cylinder bore 2a by the bypass passage 36, a large amount of EGR is possible because of high combustion stability.

  Thus, in this embodiment, for example, fuel efficiency can be improved over a wide range from a partial load operation region to a high load operation region without using a variable valve timing mechanism. That is, when increasing the amount of internal EGR by the variable valve timing mechanism, there is no problem in the partial load region, but in the high load region, the temperature of the compressed mixture rises due to the internal EGR, and the anti-knocking performance decreases. It is difficult to obtain an effective effect.

  On the other hand, in the present embodiment, the external EGR cooled by the EGR cooler 42 is introduced into the branch pipe portion 16a, while the intake control valve 20 and the intake check are not affected by the intake negative pressure of other cylinders. Since the valve 35 is disposed, the pumping loss can be further reduced by these configurations, and the fuel consumption can be suppressed.

  In this embodiment, since the intake control valve 20 is disposed at the upstream end of the branch pipe portion 16a, the passage volume from the intake control valve 20 to the intake valve 8 of the branch pipe portion 16a can be increased. Therefore, the internal EGR or the external EGR can be stored as much, and the fuel efficiency can be improved.

  In the embodiment, the EGR introduction port 41a of the EGR introduction pipe 41 is connected to the vicinity of the downstream side of the intake control valve 20 of the branch pipe part 16a. However, in the present invention, the external EGR passage is connected to the downstream end part of the branch pipe part 16a. For example, it may be connected to a connection portion to the intake port 3d. In such a case, the responsiveness in the transition period can be improved by retaining the EGR gas in the vicinity of the intake opening. That is, when the EGR gas is retained throughout the branch pipe portion 16a, for example, even when the accelerator is suddenly opened, the output is difficult to increase while the EGR gas is introduced into the cylinder, so that the accelerator response is deteriorated. .

1 is a schematic configuration diagram of a spark ignition internal combustion engine according to an embodiment of the present invention. It is sectional drawing of the said internal combustion engine.

Explanation of symbols

1 Internal combustion engine 2a Cylinder bore (cylinder),
16 Intake passage 16a Branch pipe part 17 Surge tank 18 Intake collecting pipe (intake collecting part)
20 Intake control valve 23 Throttle valve 35 Intake check valve 36 Bypass passage 41 External EGR passage 46 EGR check valve A Intake vortex

Claims (3)

Multiple cylinders,
An intake passage including a branch pipe portion communicating with each cylinder and an intake manifold portion for collecting the branch pipe portions;
One throttle valve disposed in the intake manifold,
An intake control valve disposed in each branch pipe,
A bypass passage provided to bypass each intake control valve, and generating an intake vortex flow in each cylinder;
A spark ignition internal combustion engine provided with an intake check valve provided in the bypass passage and allowing only an intake air flow to the cylinder side;
An external EGR passage is connected downstream of the intake control valve of each branch pipe portion,
A spark ignition internal combustion engine characterized in that an EGR check valve that allows only the flow of EGR gas to the cylinder side is provided in the external EGR passage. The spark ignition internal combustion engine according to claim 1,
One surge tank is interposed between the intake manifold part and the branch pipe part, and the intake control valve is disposed in the vicinity of the connection part of the branch pipe part to the surge tank. A spark ignition type internal combustion engine. The spark ignition internal combustion engine according to claim 1,
The spark ignition type internal combustion engine, wherein the external EGR passage is connected to a downstream end portion of the branch pipe portion.

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