JP2010048137A - Internal combustion engine - Google Patents

Abstract

In an internal combustion engine including an EGR device and a plurality of cylinders, variation in the combustion speed of fuel between cylinders is reduced.
In an internal combustion engine according to the present invention, an EGR gas supply port of an EGR device facing the intake system of the internal combustion engine is provided for each cylinder, and EGR gas is determined for each cylinder. It is characterized in that it is positioned so as to be biased into a predetermined area in the cylinder 14. Preferably, the EGR gas supply port 58 is positioned so that EGR gas is introduced to each cylinder 14 in a biased manner toward the outer region AO in each cylinder 14.
[Selection] Figure 2

Description

  The present invention relates to an internal combustion engine having two or more cylinders and capable of supplying EGR gas to an intake system of the engine.

  Patent Document 1 proposes a technique that makes it possible to perform more suitable premixed compression ignition combustion in a wider operating range in a premixed compression ignition combustion internal combustion engine such as a diesel engine. In this technique, the amount of EGR gas introduced into the first intake port that introduces intake air into the center of the cylinder and the second intake port that introduces intake air near the inner wall surface of the cylinder according to the operating state of the internal combustion engine. To control each. Thereby, the technology controls the distribution of the ratio (EGR rate) of the EGR gas amount in the intake air introduced into the cylinder. Specifically, when the engine operation state is in the low load operation region, the amount of EGR gas introduced into the second intake port is made larger than the amount of EGR gas introduced into the first intake port. By doing this, when the temperature near the cylinder inner wall surface becomes relatively low in such an engine operating state, the EGR rate near the cylinder inner wall surface is increased to increase the temperature of the premixed gas. enable. On the other hand, when the engine operating state is in the high load operation region, the amount of EGR gas introduced into the second intake port is made smaller than the amount of EGR gas introduced into the first intake port. By doing so, the temperature in the central part of the cylinder becomes high and pre-ignition is likely to occur during such an engine operation state, so that the premixed gas ignitability in the central part of the cylinder is suppressed. enable.

Japanese Patent Laid-Open No. 2004-346796

  By the way, in an internal combustion engine having a plurality of cylinders, that is, a multi-cylinder engine, a unique temperature distribution is generated around the combustion chamber due to the arrangement and arrangement of the plurality of cylinders. As a result, when the air-fuel mixture is combusted under the same conditions among a plurality of cylinders, the combustion speed of the fuel, that is, the air-fuel mixture, differs among the cylinders. Therefore, the output generated in each cylinder can be different.

  Accordingly, the present invention has been made in view of such a point, and an object thereof is to reduce the variation between cylinders in the combustion speed of fuel.

  An internal combustion engine according to the present invention is provided with an EGR device and a plurality of cylinders, wherein an EGR gas supply port of the EGR device facing an intake system of the internal combustion engine is provided for each cylinder, and EGR gas Is positioned so as to be biased and introduced into a predetermined region in each cylinder defined for each cylinder.

  According to such a configuration, the EGR gas supply port of the EGR device facing the intake system of the internal combustion engine is provided for each cylinder, and the EGR gas is biased and introduced into a predetermined region in the cylinder defined for each cylinder. It is positioned as follows. Therefore, the EGR gas is introduced in a biased manner to a predetermined region in each cylinder defined for each cylinder via the EGR gas supply port in each cylinder. Preferably, the predetermined region is determined so as to make the temperature distribution between the cylinders uniform. Therefore, the EGR gas introduced into each cylinder in this way acts to make the temperature distribution between the cylinders uniform. Therefore, it is possible to reduce the variation between cylinders in the combustion speed of the fuel.

  Specifically, the EGR gas supply port may be positioned so that EGR gas is introduced to each cylinder in a biased manner toward the outside region in each cylinder. The portion of the cylinder that defines the outer region is generally less susceptible to thermal influence from other cylinders than the portion of the cylinder that defines the inner region. Therefore, it is possible to moderately maintain the temperature of the outer portion of the cylinder by introducing the EGR gas biased toward the outer region. Further, by introducing the EGR gas biased toward the outside region, newly sucked air, that is, gas mainly composed of fresh air, can be introduced into the inside region of the cylinder. Thereby, it becomes possible to bring about effective cooling of the part which defines the inner side region in the cylinder.

  Preferably, two spark plugs are provided for each cylinder, and one of the two spark plugs is provided to ignite an air-fuel mixture having a high EGR gas concentration. By doing so, it is possible to appropriately increase the flame propagation speed in each cylinder.

  Preferred embodiments according to the present invention will be described below with reference to the drawings.

  First, the first embodiment will be described. In FIG. 1, an internal combustion engine 10 is, for example, an in-cylinder direct injection gasoline engine that directly injects gasoline fuel into a combustion chamber 12. The internal combustion engine 10 has four cylinders (cylinders) 14, but may have a plurality of cylinders 14 such as two, six, and eight. The internal combustion engine 10 includes a cylinder block (a water jacket or the like is not shown) 16 having a cylinder 14 and a cylinder head 18, and a piston 20 is disposed in the cylinder 14 so as to be vertically movable. The combustion chamber 12 substantially formed in the cylinder 14 so as to be sandwiched between the lower surface of the cylinder head 18 and the top surface of the piston 20 communicates with an intake passage 24 via an intake port 22 and an exhaust port 26. The exhaust passage 28 communicates with each other. The downstream end of the intake passage 24 is opened and closed by an intake valve 30, and the upstream end of the exhaust passage 28 is opened and closed by an exhaust valve 32. The combustion chamber 12 is provided with a fuel injection valve 33 so as to directly inject fuel. Two spark plugs 34 and 36 are positioned on the top of the combustion chamber 12. In FIG. 1, only one spark plug 34 provided approximately on the cylinder axis is shown. In other words, the other spark plug 36 is disposed at a position clearly deviated in a predetermined direction from the cylinder axis.

  Further, the internal combustion engine 10 includes an exhaust gas recirculation (EGR) device 40 for guiding a part of the exhaust gas flowing through the exhaust passage 28 to the intake passage 24 included in the intake system. Although not shown in FIG. 1, the EGR device 40 includes an EGR pipe that defines an EGR passage 42 that connects the exhaust passage 28 and the intake passage 24, and an EGR valve that adjusts the communication state of the EGR passage 42. ing. However, an EGR cooler for cooling the exhaust gas (EGR gas) to be recirculated may be further included in the EGR device 40, and when the EGR cooler is included, the EGR valve may be provided on the downstream side of the EGR cooler.

  The fuel injection valve 33, the spark plugs 34 and 36, the actuator for driving the EGR valve (not shown), and the like are electrically connected to an ECU (not shown) that functions as a control device for the internal combustion engine 10. . The ECU includes a CPU, a ROM, a RAM, an input / output port, an A / D and D / A converter, a storage device, and the like. Various sensors, such as a crank angle sensor, an air flow meter, and an accelerator opening sensor, which are not shown, are electrically connected to the ECU. The ECU uses the various maps and the like stored in the storage device and, based on the detection values obtained using the various sensors, etc., the fuel injection valve 33, the spark plugs 34, 36 so as to obtain a desired output. The actuator for driving the EGR valve is controlled.

  As schematically shown in FIG. 2, the cylinder head 18 of the internal combustion engine 10 is connected to an intake manifold 46 that defines a part of the intake passage 24 and a part of the exhaust passage 28. The exhaust manifold is connected. Each intake branch pipe 48 of the intake manifold 46 is divided by a partition wall 50 and connected to two independent intake ports 52 (22a, 22b) of one cylinder formed in the cylinder head 18; 54. The internal combustion engine 10 of the first embodiment is a so-called vertical internal combustion engine when mounted on a vehicle. The reference numerals # 1, # 2, # 3, and # 4 are assigned in order from the cylinder 14 located on the front side of the vehicle in the vehicle-mounted state.

  An EGR gas supply port (hereinafter referred to as an EGR port) 58, which is a downstream end portion of the EGR passage 42, communicates with the first intake port 52, but EGR gas can be supplied to the second intake port 54. Not. Here, the EGR port 58 provided for each cylinder 14 communicates with the common EGR distribution pipe portion 62 via the EGR branch pipe portion 60. An EGR valve (not shown) is provided upstream of the EGR distribution pipe 62. However, an EGR valve may be provided in common or individually in the EGR distribution pipe part 62, the EGR branch pipe part 60, and the EGR port 58.

  With respect to the two cylinders 14 on the front side, that is, the cylinders # 1 and # 2, the first intake port 52 is positioned on the front side with respect to the second intake port 54 that forms a pair. Therefore, EGR gas is introduced into the combustion chambers 12 of the cylinders # 1 and # 2 in a biased manner toward the front region.

  As shown in FIG. 3, in the intake strokes in the cylinders 14 of # 1 and # 2, the intake EI containing EGR gas is biased and introduced into the front side area AF in the cylinder 14 via the first intake port 52. Is done. On the other hand, in the same intake stroke, the intake CI not including the EGR gas is introduced to the rear region AR in the cylinder 14 via the second intake port 54. Considering the cylinder arrangement, the front side area AF is an area AO (outside area) AO located on the outer side in the cylinder arrangement direction of the internal combustion engine 10 in the cylinders # 1 and # 2, and the rear side area AR. Is a region (inner region) AI located on the inner side in the cylinder arrangement direction of the internal combustion engine 10 in the cylinders # 1 and # 2.

  On the other hand, with respect to the two rear cylinders, that is, the cylinders # 3 and # 4, the first intake port 52 is positioned on the rear side with respect to the second intake port. Therefore, EGR gas is introduced into the combustion chambers 12 of the cylinders # 3 and # 4 in a biased manner toward the rear region. As a result, here, in contrast to the cylinders 14 of # 1 and # 2, each of the cylinders 14 of # 3 and # 4 sucks intake air EI having a high EGR gas concentration on the rear side. For the cylinders # 3 and # 4, considering the cylinder arrangement, the front region AF is the inner region AI in the cylinder 14, and the rear region AR is the outer region in the cylinder 14. This is the area AO.

  FIG. 4 schematically shows all the four cylinders together. The hatched region is an example of the outside region AO, and an intake air EI having a high EGR gas concentration can be sucked in the intake stroke. An area simply surrounded by a circle without hatching is an example of the inner side area AI, and an intake CI consisting of almost fresh air can be inhaled in the intake stroke.

  In general, EGR gas, which is exhaust gas, has a temperature higher than a certain level, and has a temperature much higher than that of air taken from outside the engine. Therefore, the existence of such an EGR gas concentration distribution means that there is a clear temperature distribution in the intake air sucked into the cylinder 14.

  In an in-line four-cylinder engine equipped with an EGR device that is usually well known, EGR gas is mixed with fresh intake air in an intake passage and sucked into a combustion chamber. The plurality of cylinders are mutually affected by heat while the operation of the internal combustion engine is continued. Therefore, the cylinders on both sides have a relatively low temperature, while the cylinders closer to the center have a relatively high temperature. Such a temperature distribution tendency also occurs in each cylinder.

  In contrast, here, as described above, the EGR gas is introduced while being biased into a predetermined region within the cylinder determined for each cylinder, and the EGR gas is unevenly distributed within the cylinder 14. This makes it possible to increase the EGR gas concentration in the intake air that is sucked into the cylinder 14 where the temperature is conventionally relatively low. Therefore, the temperature distribution between the cylinders 14 can be made more uniform by the temperature distribution resulting from the uneven distribution of the gas concentrations. This also makes it possible to make the temperature distribution in the single cylinder 14 more uniform. Therefore, it is possible to reduce the difference in fuel combustion speed between the cylinders 14.

  In order to improve the combustion of the fuel, that is, the air-fuel mixture in the cylinder 14, the two spark plugs 34 and 36 are provided as described above. FIG. 5 (a) is a diagram schematically showing the two spark plugs 34 and 36 in a portion related to the # 4 cylinder in the schematic diagram of FIG. 4, and the positions of all the spark plugs in the four cylinders 14 are shown in FIG. Is schematically shown in FIG. As can be understood from FIG. 5, the spark plug 36 is disposed so as to be adapted to the outside region AO where the intake air EI having a high EGR gas concentration can be sucked. This is because fuel is difficult to burn in an air-fuel mixture with a high EGR gas concentration. That is, in order to improve the combustion speed of the fuel in the combustion chamber 12, that is, the flame propagation speed, the spark plug 36 is specially provided. Both spark plugs 34, 36 are used when EGR gas is introduced. When the EGR gas is introduced, the combustion of the fuel in the inner side region AI and the outer side region AO is promoted by the ignition by the spark plug 34 positioned substantially in the center, and the outer side by the ignition by the spark plug 36 positioned in a biased manner. Combustion of fuel in the offset region AO is promoted. Note that when the EGR gas is not introduced, only the spark plug 34 is used, but two spark plugs 34 and 36 may be used together.

  Thus, in the internal combustion engine 10, each cylinder has an EGR gas concentration distribution suitable for the cylinder, and a spark plug 36 dedicated to the air-fuel mixture having a high EGR gas concentration is provided. Therefore, it is possible to reduce the variation between the cylinders in the combustion speed of the fuel, and it is possible to appropriately burn the fuel even if there is such an EGR gas concentration distribution.

  Next, a second embodiment according to the present invention will be described. In the internal combustion engine 10 b according to the second embodiment, the partition wall 50 is not provided in the intake branch pipe 48 of the intake manifold 46. In relation to this point, the installation location of the EGR port 58 of the EGR device 40 is different from that of the first embodiment. However, since the internal combustion engine 10 of the first embodiment and the internal combustion engine 10b of the second embodiment are substantially the same except for these points, only the differences will be described here. In the following description, the same or similar components as those described above are assigned the same reference numerals as those used above, and duplicate descriptions thereof are omitted.

  The EGR port 58 in the first embodiment is positioned in a first intake port 52 that is separated and formed by the partition wall 50 in the intake branch pipe 48. However, since the intake manifold 46 of the internal combustion engine 10b does not have the partition wall 50, when the EGR port 58 is positioned at the same location and EGR gas is introduced into the intake system of the internal combustion engine 10b, the intake manifold 46 is not introduced into the cylinder 14. The EGR gas is mixed with the intake air that is newly sucked air. This can make it difficult to have an EGR gas concentration distribution in the combustion chamber 12 as described above.

  Therefore, here, the EGR port 58 is positioned in the vicinity of the intake valve 30 of each cylinder. Then, an EGR valve is provided in the EGR branch pipe portion 60, and the EGR valve is opened only when EGR gas is introduced. Note that the internal combustion engine 10 and the internal combustion engine 10b of the first embodiment are different in that the EGR port 58 is positioned so that EGR gas is introduced in each cylinder 14 so as to be biased toward the outside region AO in each cylinder 14. The same. Therefore, here, the EGR port 58 is positioned in one of the two intake ports formed in the cylinder head 18 corresponding to the outer side region AO.

  As mentioned above, although this invention was demonstrated based on two embodiment, this invention is not limited to these embodiment, Embodiment other than these is accept | permitted. For example, although the internal combustion engines 10 and 10b are both in-line four-cylinder engines, the internal combustion engine to which the present invention is applied may be a horizontally opposed engine or a V-type engine. When the present invention is applied to these types of internal combustion engines, for example, an inner side region and an outer side region in a cylinder may be determined for each bank. Since each bank is equivalent to a plurality of cylinders 14 arranged in series, the present invention can be applied as described above.

  Further, in the above-described embodiment and each modification, an example in which the present invention is applied to an in-cylinder direct injection gasoline engine has been described, but the present invention is a port injection engine that injects fuel into an intake port, a diesel engine, The present invention can be widely applied to various internal combustion engines such as a carburetor engine and an internal combustion engine using gaseous fuel. In addition, the installation method, direction, and the like of the internal combustion engine in the vehicle may be different from those of the internal combustion engines 10 and 10b in the above embodiment.

  In addition, although the present invention has been described with a certain degree of specificity in the above-described embodiments and modifications thereof, the present invention is not limited to these, and the spirit and scope of the invention described in the scope of the claims. It should be understood that various modifications and changes can be made without leaving. That is, the present invention includes modifications and changes that fall within the scope and spirit of the appended claims and their equivalents.

1 is a diagram showing a schematic configuration of a part of an internal combustion engine according to a first embodiment of the present invention. It is a schematic diagram of a part of the intake system of the internal combustion engine according to the first embodiment. It is the figure which represented typically the flow of the intake air in one cylinder of the internal combustion engine which concerns on 1st Embodiment. FIG. 2 is a diagram conceptually showing an outer side region and an inner side region in a cylinder in the internal combustion engine of the first embodiment. It is the figure which represented typically the position of two spark plugs in the internal combustion engine of 1st Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 12 Combustion chamber 14 Cylinder 24 Intake passage 28 Exhaust passage 33 Fuel injection valve 34, 46 Spark plug 42 EGR passage 46 Intake manifold 50 Partition 58 EGR gas supply port (EGR port)

Claims (3)

In an internal combustion engine including an EGR device and a plurality of cylinders,
The EGR gas supply port of the EGR device facing the intake system of the internal combustion engine is provided for each cylinder, and is positioned so that the EGR gas is biased and introduced into a predetermined region in the cylinder defined for each cylinder. An internal combustion engine characterized by that.   2. The internal combustion engine according to claim 1, wherein the EGR gas supply port is positioned so that EGR gas is introduced in a biased manner toward an outside region in each cylinder in each cylinder. There are two spark plugs for each cylinder,
The internal combustion engine according to claim 1 or 2, wherein one of the two spark plugs is provided to ignite an air-fuel mixture having a high EGR gas concentration.

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