JP2013044266A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine that can stably obtain a required EGR amount.SOLUTION: The internal combustion engine is an in-line twin engine installed in an automobile, and a stroke of a first cylinder 1a synchronizes with the stroke of a second cylinder 1b with 360° CA (Crank Angle) of phase difference therebetween. An intake port 20 of the first cylinder 1a which is one cylinder that is on expansion stroke, is connected with an intake port 20 of the second cylinder 1b which is the other cylinder that is on intake stroke, by a connecting passage 22, and an inner intake valve 16 which is continued to the intake port 20 connected by the connecting passage 22 is temporarily opened on the expansion stroke.

Description

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

  In an internal combustion engine mounted on an automobile or the like, exhaust gas recirculation is performed in which an intake system and an exhaust system are connected via an external EGR passage and a part of the exhaust gas is recirculated to the intake system through the EGR passage. An EGR valve is provided on the EGR passage, and the recirculation amount and recirculation timing of the EGR gas can be adjusted by operating the opening degree of the EGR valve in accordance with the operation region of the internal combustion engine.

  By the way, in a naturally aspirated engine, the exhaust side pressure always exceeds the intake side pressure, whereas in a turbocharged engine equipped with a turbo, the intake side pressure may exceed the exhaust side pressure depending on operating conditions. Therefore, a low-pressure loop, that is, an LPL system, in which the exhaust side extraction point for extracting exhaust gas is downstream of the turbine and the intake side introduction point for introducing EGR gas is upstream of the compressor, or the exhaust side extraction point is upstream of the turbine and the intake side introduction point is downstream of the turbine. Various ideas such as a high-pressure loop, that is, an HPL system have been made. However, in these conventional EGR systems, the amount of EGR to be circulated depends on the operating conditions as described above. In these methods, the exhaust pulsation affects the amount of EGR to be introduced.

  As another example, the technique described in Patent Document 1 discloses a technique in which a gas passage for exhausting a gas from a cylinder in an exhaust stroke from an exhaust port and circulating the gas to another cylinder is disclosed. ing. However, even in such a case, it is necessary to provide special piping for introducing EGR.

  That is, at present, in view of environmental considerations and the like, there is currently a demand for a technique that can stably circulate a sufficient amount of simple configuration EGR gas in terms of improving fuel efficiency.

Japanese Patent Application No. 1-244155

  The present invention focuses on such problems, and an object of the present invention is to provide an internal combustion engine that can stably obtain a necessary EGR amount.

  In order to achieve such an object, the present invention takes the following measures.

  That is, the internal combustion engine according to the present invention is a multi-cylinder internal combustion engine, wherein an intake port of one cylinder in an expansion stroke and an intake port of another cylinder in an intake stroke are connected by a connection passage, The intake valve that is continuous with the intake port connected through the connection passage is temporarily opened during the expansion stroke.

  In such a case, since the intake port of one cylinder and the intake port of the other cylinder in the intake stroke are connected by a connection passage, the intake valve is temporarily opened during the expansion stroke, thereby increasing the pressure. The exhaust gas taken out from the cylinder is quickly circulated through the connection passage to another cylinder having an intake stroke, that is, a negative pressure. Thus, by using the pressure difference between the cylinders, the EGR gas can be circulated without being affected by the operating conditions. Moreover, since it is the structure which recirculates EGR gas, without providing special piping outside, unlike the conventional system, EGR gas can be recirculated without being influenced by pulsation.

  An internal combustion engine according to the present invention is a multi-cylinder internal combustion engine, wherein an exhaust port of one cylinder in an expansion stroke and an exhaust port of another cylinder in an intake stroke are connected by a connection passage, An exhaust valve connected to the exhaust port connected through the connection passage is temporarily opened in the intake stroke and the expansion stroke.

  In such a case, since the exhaust port of one cylinder in the expansion stroke and the exhaust port of the other cylinder in the intake stroke are connected by a connection passage, the exhaust valve is temporarily opened during the expansion stroke. The exhaust gas taken out from the cylinder that is at a high pressure by the valve is quickly circulated through the connection passage to the exhaust valve that is temporarily opened in another cylinder that is in the intake stroke, that is, the negative pressure. The That is, even in this configuration, the EGR gas can be circulated without depending on the operating conditions by using the pressure difference between the cylinders as described above. Moreover, since it is the structure which recirculates EGR gas, without providing special piping outside, unlike the conventional system, EGR gas can be recirculated without being influenced by pulsation.

  ADVANTAGE OF THE INVENTION According to this invention, the internal combustion engine which can obtain the required EGR amount stably can be provided.

The typical block diagram of the internal combustion engine which concerns on 1st embodiment of this invention. The time chart which concerns on the same embodiment. Other time charts. The typical block diagram of the internal combustion engine which concerns on 2nd embodiment of this invention. The time chart which concerns on the same embodiment. Other time charts. The typical block diagram of the internal combustion engine which concerns on the modification of this invention. The typical block diagram of the internal combustion engine which concerns on the other modification of this invention.

<First embodiment>
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

  The engine as the internal combustion engine of this embodiment is an in-line two-cylinder engine mounted on an automobile, and the stroke of the first cylinder 1a and the stroke of the second cylinder 1b have a phase difference of exactly 360 ° CA (crank angle). To synchronize.

  FIG. 1 schematically shows the cylinders 1a and 1b, the intake system 2 and the exhaust system 3 of the engine. As shown in the figure, this engine is provided with two intake ports 20 and two exhaust ports 30 for each of the cylinders 1a and 1b. That is, the first cylinder 1a has an outer exhaust valve 11, an inner exhaust valve 12, an outer intake valve 16, and an inner intake valve 15. Similarly, the second cylinder 1b has an outer exhaust valve 13, an inner exhaust valve 14, an outer intake valve 18, and an inner intake valve 17.

  Here, in the engine as the internal combustion engine according to the present embodiment, the intake port 20 of the first cylinder 1a which is one cylinder in the expansion stroke and the intake port 20 of the second cylinder 1b which is another cylinder in the intake stroke are connected. The inner intake valves 16 and 17 that are connected by the passage 22 and continue to the intake port 20 connected by the connection passage 22 are temporarily opened during the expansion stroke.

  Hereinafter, the configuration of the intake system 2 and the exhaust system 3 and the behavior of the valves 11 to 18 will be mainly described in the present embodiment.

  The intake system 2 communicates and blocks between a surge tank 21 for supplying air to a total of four intake ports 20, a connection passage 22 that connects the inner valves 16 and 17, and the surge tank 21 and the connection passage 22. And a control valve 23 capable of controlling the flow rates of air and exhaust. The connection passage 22 is made of a material having higher heat resistance than that of the normal intake port 20 in view of high temperature inflow. Further, in the present embodiment, the diameter of the pipe line constituting the connection passage 22 is set smaller than the diameter of the pipe line constituting the outer intake port 20. Since the existing control valve 23 that can control the flow rate is used, detailed description thereof is omitted.

  The exhaust system 3 has a normal configuration in which four exhaust ports 30 connected to the inner exhaust valves 12 and 13 and the outer exhaust valves 11 and 14 are integrated into one pipe line.

  2 and 3 show valve lift curves of the intake valves 15 to 18 and the exhaust valves 11 to 14 in the respective cylinders 1a and 1b. In this embodiment, the amount and timing of the valve lift shown in the figure are realized by adjusting the cam shapes provided on the intake camshaft and the exhaust camshaft (not shown). Further, for example, in consideration of the operation region where EGR introduction is unnecessary, the cam that can act on the inner intake port 20 is configured in two stages, and the intake camshaft is moved in the axial direction so that EGR is introduced and not introduced. And may be switched. And of course, you may implement | achieve the operation | movement of the valve | bulb disclosed by this embodiment not by a cam but by valve control by an electromagnetic valve. Hereinafter, the operation of each of the valves 11 to 18 will be specifically described.

  First, in the first cylinder 1a, the inner intake valve 16 opens during the expansion stroke, and the exhaust valves 11 and 12 open later. On the other hand, when the inner intake valve 16 is opened, the inner intake valve 17 of the second cylinder 1b is also opened at the same timing. At this time, the second cylinder 1b is in the intake stroke, both intake valves 17, 18 are open, and a total of three intake valves 16, 17, 18 are open. Further, the lift amount of the inner intake valves 16, 17 is lower than the lift amount of the outer intake valve 18, and the operating angle is narrow. In the present embodiment, the valve opening amounts of the inner intake valves 16 and 17 are maximized at, for example, an expansion bottom dead center (BDC) and an intake bottom dead center (BDC). Although the inner intake valve 16 is closed during the exhaust process of the first cylinder 1a, both the exhaust valves 11 and 12 continue to operate in the same manner as normal exhaust valves. On the other hand, the inner intake valve 17 opened in the second cylinder 1b is closed simultaneously with the inner intake valve 15 of the first cylinder 1a during the compression stroke.

  Thus, the exhaust gas introduced from the inner intake valve 16 of the first cylinder 1a is directly taken into the second cylinder 1b during the intake stroke through the inner intake valve 17. The inner intake valve 16 of the first cylinder 1a has a high differential pressure due to the expansion stroke, and the inner intake valve 17 of the second cylinder 1b has a large differential pressure due to the intake pressure due to the lowering of the piston. Can be installed without piping.

  In the second cylinder 1b, as in the first cylinder 1a, the inner intake valve 17 opens during the expansion stroke, and the exhaust valves 13 and 14 open later. On the other hand, when the inner intake valve 17 is opened, the inner intake valve 16 of the first cylinder 1a is also opened at the same timing. During the exhaust process of the second cylinder 1b, the inner intake valve 17 is closed, but both the exhaust valves 13, 14 continue to operate in the same manner as normal exhaust valves. On the other hand, the exhaust valve 16 opened in the first cylinder 1a is closed simultaneously with the inner intake valve 17 of the second cylinder 1b during the compression stroke.

  That is, the exhaust gas introduced from the inner intake valve 17 of the second cylinder 1b is directly drawn into the first cylinder 1a during the intake stroke through the inner intake valve 16. The inner intake valve 17 of the second cylinder 1b has a high pressure due to the expansion stroke, and the inner intake valve 16 of the first cylinder 1a has a large differential pressure due to the suction pressure due to the lowering of the piston. As a result, a large amount of EGR gas is also obtained. Can be installed without external piping.

  In this embodiment, it is also possible to adjust the EGR amount to be circulated and the EGR rate by controlling the control valve 23. That is, when the control valve 23 is closed, the largest amount of EGR gas can be circulated by effectively utilizing the above-described differential pressure between the cylinders 1a and 1b. The amount of EGR to be circulated and the EGR rate can be adjusted by adjusting the opening of the control valve 23 according to the operating state.

  With the configuration as described above, in the engine according to the present embodiment, the inner intake ports 20 are connected to each other through the connection passage 22, so that the inner intake valves 16 and 17 are temporarily opened during the expansion stroke. As a result, the exhaust gas taken out from the high-pressure cylinder quickly passes through the connection passage 22 to the intake port 20 of another cylinder having a negative pressure, that is, through the inner intake valves 17 and 16 immediately. Perfused. That is, by utilizing such a pressure difference between the cylinders 1a and 1b, it is possible to circulate a large amount of EGR gas without being influenced by operating conditions. In addition, since the EGR gas is circulated without providing any special piping outside, the EGR gas is circulated without being affected by exhaust pulsation unlike the conventional method.

<Second embodiment>
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings.

  The engine as the internal combustion engine of this embodiment is an in-line two-cylinder engine in which the stroke of the first cylinder 1a and the stroke of the second cylinder 1b are synchronized with a phase difference of exactly 360 ° CA (crank angle), as in the above embodiment. It is.

  As schematically shown in FIG. 3, this engine is provided with two intake ports 20 and two exhaust ports 30 for each of the cylinders 1a and 1b, as in the above embodiment. That is, the first cylinder 1a has an outer exhaust valve 11, an inner exhaust valve 12, an outer intake valve 15, and an inner intake valve 16. Similarly, the second cylinder 1b has an outer exhaust valve 14, an inner exhaust valve 14, an outer intake valve 18 and an inner intake valve 17.

  Here, in the engine as the internal combustion engine according to the present embodiment, the exhaust port 30 of one cylinder 1a, 1b in the expansion stroke and the exhaust port 30 of the other cylinder 1b, 1a in the intake stroke are connected by a connection passage 32. The exhaust valves 12 and 13 connected to the exhaust port 30 connected by the connection passage 32 are temporarily opened during the intake stroke and the expansion stroke.

  Hereinafter, the configuration of the intake system 2 and the exhaust system 3 and the behavior of the valves 11 to 18 will be mainly described in the present embodiment.

  The intake system 2 has a normal configuration having a total of four intake ports 20 connected to the intake valves 15 to 18 and a surge tank 21 for supplying air to the intake ports 20.

  The exhaust system includes a total of four exhaust ports 30 connected to the four exhaust valves 11 to 14, an aggregation portion 31 that collects exhaust gas from the exhaust ports 30, and a connection passage 32 that connects the inner exhaust valve ports to each other. And a control valve 33 capable of controlling the flow rate of exhaust gas by communicating and blocking between the concentrating part 31 and the connection passage 32. Further, in the present embodiment, the diameter of the pipe line constituting the connection passage 32 is set to be smaller than the diameter of the pipe line constituting the exhaust port 30 continuing to each of the outer exhaust valves 11 and 14.

  5 and 6 show valve lift curves of the intake valves 15 to 18 and the exhaust valves 11 to 14 in the respective cylinders 1a and 1b. Hereinafter, the operation of each of the valves 11 to 18 will be specifically described.

  First, in the first cylinder 1a, the inner exhaust valve 12 is opened during the expansion stroke, and the outer exhaust valve 11 is opened with a delay. On the other hand, when the inner exhaust valve 12 is opened, the inner exhaust valve 13 of the second cylinder 1b is also opened at the same timing. At this time, the second cylinder 1b is in the intake stroke, both intake valves 17, 18 are open, and a total of three valves 13, 17, 18 are open. Further, the lift amount of the inner exhaust valves 12, 13 is lower than the lift amount of the outer intake valves 11, 14, and the operating angle is narrow. In the present embodiment, the valve opening amounts of the inner exhaust valves 12 and 13 are maximized at, for example, an expansion bottom dead center (BDC) and an intake bottom dead center (BDC). Although the inner exhaust valve 12 is closed during the exhaust process of the first cylinder 1a, the outer exhaust valve 11 continues the same operation as a normal exhaust valve. On the other hand, the two intake valves 17 and 18 and the inner exhaust valve 13 opened in the second cylinder 1b are closed simultaneously with the inner exhaust valve 12 of the first cylinder 1a during the compression stroke.

  In this way, the exhaust gas from the inner exhaust valve 12 of the first cylinder 1a is directly drawn into the second cylinder 1b during the intake stroke through the inner exhaust valve 13. The inner intake valve 12 of the first cylinder 1a has a high pressure due to the expansion stroke, and the inner exhaust valve 13 of the second cylinder 1b has a large pressure difference due to the suction pressure due to the lowering of the piston. As a result, a large amount of exhaust gas is removed. Introduced without external piping.

  In the second cylinder 1b, as in the first cylinder 1a, the inner exhaust valve 13 is opened during the expansion stroke, and the outer exhaust valve 14 is opened with a delay. On the other hand, when the inner exhaust valve 13 is opened, the inner exhaust valve 12 of the first cylinder 1a is also opened at the same timing. During the exhaust process of the second cylinder 1b, the inner exhaust valve 13 is closed, but the outer exhaust valve 14 continues to operate in the same manner as a normal exhaust valve. On the other hand, the inner exhaust valve 12 opened in the first cylinder 1a is closed simultaneously with the two intake valves 15 and 16 and the inner exhaust valve 13 of the second cylinder 1b during the compression stroke.

  That is, the exhaust gas introduced from the inner exhaust valve 13 of the second cylinder 1b is directly taken into the first cylinder 1a during the intake stroke through the inner exhaust valve 12. The inner exhaust valve 13 of the second cylinder 1b has a high pressure due to the expansion stroke, and the inner exhaust valve 12 of the first cylinder 1a has a large pressure difference due to the suction pressure due to the lowering of the piston. As a result, a large amount of EGR gas is also obtained. Is introduced without external piping.

  In this embodiment, it is also possible to adjust the EGR amount to be circulated by controlling the control valve 33. That is, when the control valve 33 is closed, the largest amount of EGR gas can be circulated by effectively utilizing the above-described differential pressure between the cylinders. The amount of EGR to be circulated and the EGR rate can be adjusted by adjusting the opening of the control valve 33 according to the operating state.

  By setting it as the above structures, since the inner exhaust ports 30 are connected by the connection channel | path 32, the engine which concerns on this embodiment becomes high pressure by opening temporarily in an expansion stroke. Exhaust gas taken out from the cylinders 1a and 1b is quickly circulated through the connection passage 32 to the exhaust ports 30 of the other cylinders 1b and 1a having a negative pressure, that is, negative pressure. That is, as in the first embodiment described above, by utilizing such a pressure difference between the cylinders 1a and 1b, it is possible to circulate a large amount of EGR gas regardless of the operating conditions. In addition, since the EGR gas is circulated without providing any special piping outside, the EGR gas is circulated without being affected by exhaust pulsation unlike the conventional method.

<Modification>
Below, the modification of this embodiment is demonstrated. About the modification, while attaching the same code | symbol as said 1st embodiment, the detailed description is abbreviate | omitted.

  As shown in FIG. 7, the internal combustion engine according to the present modification has a configuration in which the control valve 23 is omitted from the configuration of the first embodiment.

  Even in such a case, the EGR recirculation only by opening and closing the inner intake valves 16 and 17 is possible, and the exhaust gas from the inner intake valves 16 and 17 returns to the surge tank 21 as it is. In addition, the improvement of the EGR rate and the homogeneous intake can be realized together.

<Other variations>
Further, the engine according to the present invention is not limited to the aspect having a plurality of intake ports 20 as in the above-described embodiment. As shown in FIG. 8, each cylinder 1a, 1b may have one intake port 20 and intake valves 15, 17. In this case, in addition to the operation in the normal intake stroke, the intake valves 15 and 17 may be temporarily opened in the expansion process to introduce exhaust gas. Even in such a case, the EGR gas recirculation similar to that in the above embodiment can be realized.

  Although the embodiment of the present invention has been described above, the specific configuration of each unit is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the above embodiment, an in-cylinder injection type engine is used, but the present invention may of course be applied to a port injection type engine. Moreover, although the aspect which applied this invention with respect to the inline two cylinder engine was disclosed in the said embodiment, of course, it is not restricted to a two cylinder engine. For example, in the case of an in-line four-cylinder engine, the ignition order is the order of the first cylinder, the third cylinder, the second cylinder, and the fourth cylinder, and the first cylinder, the second cylinder, the third cylinder, and the fourth cylinder that are adjacent to each other. If the stroke is synchronized with a phase difference of 360 ° CA (crank angle), the present invention can be applied as in the above embodiment.

  In the first embodiment, the valve opening amount of the inner intake valve is maximized at, for example, the expansion bottom dead center (BDC) and the intake bottom dead center (BDC), but is not limited to this mode. For example, in the case of an internal combustion engine provided with a variable valve timing mechanism, the timing at which the valve opening amount becomes maximum can be changed. Of course, the opening amount of the inner exhaust valve in the second embodiment is also similar, and when the variable valve timing mechanism is provided, the timing at which the opening amount becomes maximum can be changed.

  In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

  The present invention can be used as an internal combustion engine having an exhaust gas recirculation device.

1a ... cylinder (first cylinder)
1b ... cylinder (second cylinder)
16, 17 ... Intake valve (inner intake valve)
12, 13 ... Exhaust valve (inner exhaust valve)
20 ... Intake port 30 ... Exhaust port 22, 32 ... Continuous passage 23, 33 ... Control valve

Claims (2)

A multi-cylinder internal combustion engine,
The intake port of one cylinder in the expansion stroke and the intake port of the other cylinder in the intake stroke are connected by a connection passage,
An internal combustion engine characterized in that an intake valve continuous with an intake port connected through the connection passage is temporarily opened during an expansion stroke. A multi-cylinder internal combustion engine,
The exhaust port of one cylinder in the expansion stroke and the exhaust port of the other cylinder in the intake stroke are connected by a connection passage,
An internal combustion engine characterized in that an exhaust valve continuous with an exhaust port connected through the connection passage is temporarily opened during an intake stroke and an expansion stroke.

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