JP4930064B2 - Gas introduction device for internal combustion engine - Google Patents

Description

  The present invention includes a gas introduction passage that is connected to an intake upstream side of each branch pipe of an intake manifold provided in an intake passage of an internal combustion engine having a plurality of cylinders and introduces a gas different from intake air into the intake passage. The present invention relates to a gas introduction device for an internal combustion engine.

  Conventionally, as a gas introduction device of this type of internal combustion engine, for example, there is one described in Patent Document 1. FIG. 4 shows an outline of a blow-by gas introduction device that has been generally adopted as such a gas introduction device, including the device described in Patent Document 1.

As shown in FIG. 4, the blow-by gas introduction device 104 of the internal combustion engine connects the crankcase and the intake passage 2 and introduces the blow-by gas staying in the crankcase into the intake passage 2. 41 is provided. According to such a blow-by gas introduction device 104, the blow-by gas staying in the crankcase can be introduced into the intake passage 2 and burned together with the air-fuel mixture in the combustion chamber.
JP-A-9-317569

  By the way, in an internal combustion engine provided with such a blow-by gas introduction device 104, the oil component contained in the blow-by gas accumulates on the intake valve, which may cause the valve opening / closing function to deteriorate. Further, in such a blow-by gas introduction device 104, normally, as shown in FIG. 4, the connection portion 42 between the blow-by gas introduction passage 41 and the intake passage 2 is, for example, an intake air due to the layout of the internal combustion engine. Among the branch pipes 21A to 21D of the manifold 20, it is provided at a position closest to the branch pipe 21A corresponding to the first cylinder # 1 and farthest from the branch pipe 21D corresponding to the fourth cylinder # 4. . For this reason, among the branch pipes 21 </ b> A to 21 </ b> D of the intake manifold 20, the branch pipe closer to the connection part 42 tends to increase the amount of blow-by gas introduced, and the branch pipe farther from the connection part has a higher blow-by gas content. The introduction amount tends to decrease (in order of increasing introduction amount, first branch pipe 21A> second branch pipe 21B> third branch pipe 21C> fourth branch pipe 21D). Such blow-by gas flows into the first branch pipe 21 </ b> A closest to the connection portion 42 between the blow-by gas introduction passage 41 and the intake passage 2 among the specific cylinders, that is, the branch pipes 21 </ b> A to 21 </ b> D of the intake manifold 20. When a large amount is introduced to the corresponding first cylinder # 1, the amount of oil component accumulated in the intake valve provided in the first cylinder # 1 becomes the intake valve provided in the other cylinders # 2 to # 4. There is a concern that the function of the intake valve is greatly reduced compared to other intake valves.

  Note that such a problem caused by a large amount of gas introduced into the intake passage being biased to the specific cylinder is not limited to the blow-by gas introduction device, but the evaporated fuel that remains in the fuel tank of the internal combustion engine. Of the intake manifold of the internal combustion engine having a plurality of cylinders, such as an evaporative fuel introduction device that introduces exhaust gas into the intake passage and an exhaust introduction device that introduces exhaust gas from the internal combustion engine into the intake passage. The gas introduction device of the internal combustion engine having a gas introduction passage that is connected to the gas passage and introduces a gas different from the intake air into the intake passage is generally common.

  The present invention has been made in view of such circumstances, and an object of the present invention is to connect intake air upstream of each branch pipe of an intake manifold provided in an intake passage of an internal combustion engine having a plurality of cylinders. In the gas introduction device of the internal combustion engine having a gas introduction passage for introducing another gas into the intake passage, the gas introduced by the gas introduction device is in a branch pipe closest to the connection portion between the gas introduction passage and the intake passage. An object of the present invention is to provide a gas introduction device for an internal combustion engine that can suppress the introduction of a large amount in a corresponding cylinder.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
The invention of claim 1 is provided with a common gas inlet passage at the branch pipes that are connected to the intake upstream side of the branch pipes of an intake manifold provided in an intake passage of an internal combustion engine having a plurality of cylinders, the gas introduction device for an internal combustion engine you introduced into the intake passage a different gas from the intake through the gas introduction passage, provided in the gas introduction passage includes a control valve for controlling the introduction of the gas, the control valve The valve is closed except for a specific valve opening period, and in the specific valve opening period, a position closest to the connection part between the gas introduction passage and the intake passage among the branch pipes of the intake manifold. The gist of the invention is that it includes a predetermined period immediately after the intake valve of the cylinder corresponding to the branch pipe shifts from the open state to the closed state.

  When the piston of the internal combustion engine moves down while the intake valve is open, negative pressure is generated in the cylinder, and the intake air in the intake passage is drawn into the cylinder. When the intake valve is closed, the intake air drawn to the vicinity of the intake valve is changed in flow by colliding with the closed intake valve, and the intake port is changed through the branch pipe of the intake manifold. It will come back to the gathering part.

According to the above-described configuration, the control valve of the gas introduction device is closed except for a specific valve opening period, and during the specific valve opening period , the gas introduction passage and the intake passage among the branch pipes of the intake manifold. Includes a predetermined period immediately after the intake valve of the cylinder corresponding to the branch pipe located closest to the connection with the transition from the open state to the closed state, that is, a period in which a backflow of intake air occurs in the branch pipe due to the way the gas introduced into the intake passage through the connecting portion between the gas introduction passage and the intake passage is influenced by the back flow of intake air occurring in the branch pipe of the position closest to the connecting portion It diffuses into the collection of intake manifolds. The gas diffused in the collecting portion in this way is mixed with the intake air from the intake upstream side and introduced into each cylinder from each branch pipe of the intake manifold. Therefore, the gas introduced by the gas introduction device corresponds to a specific cylinder, that is, a cylinder corresponding to the branch pipe closest to the connection portion between the gas introduction passage and the intake passage among the branch pipes of the intake manifold. Therefore, it is possible to suppress the introduction of a large amount in the meantime.

  According to a second aspect of the present invention, in the gas introduction device for an internal combustion engine according to the first aspect, when the control valve is opened during the predetermined period, the control valve is set so that the intake valve is closed. The gist is that the valve is opened immediately before.

  According to this configuration, the control valve is opened immediately before the intake valve is closed, that is, from when the intake valve is open and intake air in the intake manifold and intake port is drawn toward the cylinder. The gas in the gas introduction passage can be introduced more into the intake passage using the force for drawing in the intake air. Then, after the intake valve is closed, the gas introduced in this way can be diffused into the intake manifold collection portion by the intake air flowing back to the collection portion through the intake manifold branch pipe. .

According to a third aspect of the present invention, in the gas introduction device for an internal combustion engine according to the first or second aspect, the intake valve starts immediately before the intake valve shifts from the closed state to the open state during the specific valve opening period. The gist is that it further includes a predetermined period until immediately after .

  Immediately after the intake valve starts to open, the pressure in the cylinder is higher than the pressure in the intake port, so that the intake air is temporarily supplied from the intake port to the collecting portion via the branch pipe of the intake manifold. In reverse.

According to the above configuration, during the specific valve opening period, among the branch pipes of the intake manifold, the cylinders corresponding to the branch pipes closest to the connection portion between the gas introduction passage and the intake passage are provided. In addition, a predetermined period from immediately before to immediately after the intake valve is changed from the closed state to the open state is further included. Can be diffused. For this reason, in addition to the effect of the invention described in claim 1, it is possible to further secure a period during which the intake air can be diffused by utilizing the backflow of the intake air generated in the branch pipe, and more gas can be It can be introduced into the cylinder. As a result, while ensuring the amount of gas introduced by the gas introduction device, it is possible to suppress the introduction of a large amount of the same gas to the specific cylinder.

  In an internal combustion engine equipped with a blow-by gas introduction device that introduces blow-by gas staying in the crankcase into the intake passage, an oil component contained in the blow-by gas is accumulated in the intake valve, so that its opening / closing function is lowered. Further, a large amount of such blow-by gas is biased into a specific cylinder, that is, a cylinder corresponding to the branch pipe closest to the connection portion between the gas introduction passage and the intake passage among the branch pipes of the intake manifold. Then, the amount of oil component deposited on the intake valve provided in the specific cylinder is larger than that of the intake valve provided in other cylinders, and the function of the intake valve is larger than that of other intake valves. We are anxious about it falling.

  In this regard, according to the invention described in claim 4, the blow-by gas introduction device that introduces the blow-by gas remaining in the crankcase of the internal combustion engine into the intake passage is described in any one of claims 1 to 3. When the described invention is applied, it is possible to suppress the function of the specific intake valve from being greatly reduced as compared with other intake valves due to the accumulation of the oil component of the blow-by gas.

  In an internal combustion engine equipped with an evaporative fuel introduction device that introduces evaporative fuel staying in a fuel tank into an intake passage, the evaporative fuel is a specific cylinder, i.e., a gas introduction passage and an intake air in each branch pipe of an intake manifold. If a large number of cylinders corresponding to the branch pipes closest to the connection with the passage are introduced to the cylinder, variations in the air-fuel ratio will occur among the cylinders, resulting in fluctuations in engine speed, for example. Is concerned.

  In this regard, according to the fifth aspect of the present invention, the evaporative fuel introduction device that introduces the evaporative fuel staying in the fuel tank of the internal combustion engine into the intake passage is described in any one of the first to fourth aspects. By applying the invention, it is possible to suppress variations in the air-fuel ratio among the cylinders and fluctuations in the engine rotational speed due to the variations.

  In an internal combustion engine equipped with an EGR gas introduction device that introduces exhaust gas from an internal combustion engine into an intake passage, the exhaust gas is connected to a specific cylinder, that is, a connection portion between the gas introduction passage and the intake passage among the branch pipes of the intake manifold. If a large amount of the exhaust gas is introduced to the cylinders corresponding to the branch pipes closest to the exhaust pipe, the amount of exhaust gas introduced into the other cylinders cannot be sufficiently secured, and the NOx emission amount in the entire internal combustion engine is reduced. As a result, the exhaust properties deteriorate.

  In this regard, if the invention according to any one of claims 1 to 5 is applied to an EGR gas introduction device that introduces exhaust gas from an internal combustion engine into an intake passage as in the invention described in claim 6, Such deterioration of exhaust properties can be suppressed.

Hereinafter, an embodiment in which the gas introducing device according to the present invention is embodied as a blow-by gas introducing device mounted on an in-line four-cylinder internal combustion engine will be described with reference to FIGS. 1 and 2.
FIG. 1 is a block diagram showing a schematic configuration of the blow-by gas introducing device of this embodiment.

  As shown in FIG. 1, the intake passage 2 of the internal combustion engine is provided with a throttle body 23 and an intake manifold 20 in order from the intake upstream side. Among these, the throttle body 23 is provided with a throttle valve 24 that regulates intake air in accordance with the opening thereof. The intake manifold 20 is connected to the throttle body 23 and functions as a surge tank. The intake manifold 20 branches from the collective portion 22 and communicates with the cylinders # 1 to # 4 of the internal combustion engine. The branch pipes 21A to 21D are provided. In addition, intake ports for connecting these to the cylinders # 1 to # 4 are provided on the intake downstream side of the branch pipes 21A to 21D, respectively.

  The blow-by gas introduction device 4 introduces blow-by gas that stays in the crank case into the intake passage 2 through a blow-by gas introduction passage 41 that connects the crankcase of the internal combustion engine and the collecting portion 22 of the intake manifold 20. The blow-by gas introduced into the intake passage 2 is combusted with the air-fuel mixture and then discharged into the exhaust passage. Here, the connection part 42 between the blow-by gas introduction passage 41 and the collecting part 22 is formed at a position closest to the first branch pipe 21A among the branch pipes 21A to 21D. The distance from the branch pipes 21A to 21D becomes longer in the order of the first branch pipe 21A, the second branch pipe 21B, the third branch pipe 21C, and the fourth branch pipe 21D.

  The blow-by gas introduction passage 41 is provided with a control valve 43 that controls the introduction of blow-by gas. The control valve 43 is controlled to open and close based on a drive signal from the electronic control unit 44.

  The electronic control unit 44 detects the crank angle CA based on a detection signal output from a crank angle sensor 45 provided in the vicinity of the crankshaft, and performs opening / closing control of the control valve 43 based on the crank angle CA. .

Next, the opening / closing control of the control valve 43 performed through the electronic control unit 44 will be described in detail with reference to FIG.
FIG. 2 shows (a) the opening / closing state of an intake valve provided in the first cylinder # 1, (b) the change rate of the mass flow rate of intake air in the intake port connected to the first cylinder # 1, and (c) control. 6 is a timing chart showing the relationship between the open / closed state of the valve 43 and the crank angle CA.

As shown in FIG. 2A, the intake valve of the first cylinder # 1 is opened during the period t2 to t6, and is closed during the other periods.
Here, as shown in FIG. 2B, in the period t2 to t4 immediately after the intake valve of the first cylinder # 1 starts to open, the pressure in the first cylinder # 1 is increased in the intake port. Therefore, the intake air flows backward from the intake port to the collecting portion 22 via the branch pipe 21A of the intake manifold 20 (the flow of the intake air is indicated by an arrow b in FIG. 1). Show).

  Further, when the piston of the first cylinder # 1 moves down while the intake valve is opened, a negative pressure is generated in the first cylinder # 1, so that the intake air in the intake passage 2 is sucked into the first cylinder # 1. 1 is drawn (indicated by arrow a in FIG. 1). Then, as shown in FIG. 2B, in the period t6 to t7 after the intake valve is closed, the first branch pipe 21A and the intake port of the intake manifold 20 are drawn from the intake upstream side to that time. The intake air changes its flow by colliding with the closed intake valve and flows back from the intake port to the collecting portion 22 through the first branch pipe 21A (the flow of the intake air is indicated by the arrow b in FIG. 1). ).

  In this embodiment, as shown in FIG. 2 (c), the control valve 43 is opened at the timing t1 immediately before the intake valve of the first cylinder # 1 is opened, and the above-described intake air reverse flow The valve is closed at the timing t3 included in the period t2 to t4 in which the occurrence of. That is, the control valve 43 is closed at a timing t3 before the timing t4 at which the backflow of the intake air disappears and the intake air starts to flow from the collecting portion 22 to the branch pipe 21A. Thus, introduction of blow-by gas into the first cylinder # 1 together with intake air that has started to flow from the collecting portion 22 to the branch pipe 21A is suppressed. Further, the control valve 43 is opened at a timing t5 immediately before the intake valve of the first cylinder # 1 is closed, and is closed at a timing t7 when the reverse flow of the intake air generated in the intake port and the intake manifold disappears. I try to let them.

According to the blow-by gas introducing device according to this embodiment described above, the effects listed below can be obtained.
(1) The control valve 43 is opened during a predetermined period t6 to t7 immediately after the intake valve of the first cylinder # 1 shifts from the open state to the closed state. As a result, the blow-by gas introduced into the intake passage 2 through the connection portion 42 between the blow-by gas introduction passage 41 and the intake passage 2 is the intake air generated in the first branch pipe 21A closest to the connection portion 42. Under the influence of the backflow, it is diffused into the collecting portion 22 of the intake manifold 20. The gas diffused into the collecting portion 22 in this manner is mixed with the intake air from the intake upstream side, and is introduced from the branch pipes 21A to 21D of the intake manifold 20 into the cylinders # 1 to # 4. become. For this reason, the gas introduced by the blow-by gas introduction device 4 is the most with respect to the connection portion 42 between the blow-by gas introduction passage 41 and the intake passage 2 among the branch pipes 21A to 21D of the specific cylinder, that is, the intake manifold 20 It is possible to suppress the introduction of a large amount in the first cylinder # 1 corresponding to the first branch pipe 21A in the close position. As a result, it is possible to prevent the function of the specific intake valve from being greatly deteriorated as compared with other intake valves due to the accumulation of oil in the blow-by gas.

  (2) When the control valve 43 is opened during the period t6 to t7, the control valve 43 is opened at timing t5 immediately before the intake valve of the first cylinder # 1 is closed. . As a result, the control valve 43 opens immediately before the intake valve is closed, that is, from when the intake valve is open and intake air in the intake manifold 20 and intake port is drawn toward the first cylinder # 1. Is done. For this reason, a large amount of blow-by gas in the blow-by gas introduction passage 41 can be introduced into the intake passage 2 by using a force for drawing in intake air. Then, in the period t6 to t7 after the intake valve is closed, the gas introduced in this way is taken in by the intake air flowing back to the collecting portion 22 through the first branch pipe 21A of the intake manifold 20 from the intake port. It can be diffused into the assembly 22 of the manifold 20.

  (3) The control valve 43 is also opened during the period t2 to t3 immediately after the intake valve of the first cylinder # 1 shifts from the closed state to the opened state. As a result, the blow-by gas can be diffused in the collecting portion 22 of the intake manifold 20 due to the backflow of the intake air generated immediately after the intake valve is opened. For this reason, in addition to the period t3 to t4 of the above effect, it is possible to further secure a period during which the intake air can be diffused by utilizing the backflow of the intake air generated in the first branch pipe 21A, and more blow-by gas can be saved. It can be introduced into each cylinder # 1 to # 4. As a result, while ensuring the amount of blow-by gas introduced by the blow-by gas introduction device 4, it is possible to suppress the introduction of a large amount of the blow-by gas toward the first cylinder # 1.

  (4) Timing t3 included in the period t2 to t4 during which the intake backflow occurs, that is, before the timing t4 at which the intake backflow disappears and the intake air starts to flow from the collecting portion 22 to the branch pipe 21A. The control valve 43 is closed at timing t3. Thereby, it is possible to prevent the blow-by gas from being introduced into the first cylinder # 1 together with the intake air that has started to flow from the collecting portion 22 to the branch pipe 21A.

  Note that the gas introduction device for an internal combustion engine according to the present invention is not limited to the configuration exemplified in the above-described embodiment, and can be implemented as, for example, the following forms appropriately modified.

  As in the above embodiment, the period from the timing t5 immediately before the intake valve of the first cylinder # 1 is closed to the timing t7 at which the backflow of the intake air generated in the intake port and the intake manifold disappears, t5 to t7 In addition, in order to introduce more blow-by gas, it is desirable to open the control valve 43 during the period t2 to t3 during which intake air reverse flow occurs immediately after the intake valve is opened. However, as long as a necessary amount of blow-by gas can be introduced, the control valve 43 does not have to be opened in the period t2 to t3. That is, the control valve 43 may be opened only during the period t5 to t7. Further, when it is necessary to introduce more blow-by gas, the control valve 43 may be opened at a timing earlier than the timing t1.

  In the above embodiment, the control valve 43 is opened at the timing t5 immediately before the intake valve of the first cylinder # 1 is closed, but the opening timing of the control valve 43 is limited to this. is not. Immediately before the intake valve is closed, the intake valve and the intake port are drawn into the cylinder because the intake valve is open. For example, when the total length of the branch pipe and the intake port is long Therefore, the intake air drawn into the branch pipe and the intake port is less likely to return to the collection portion even if a backflow occurs thereafter, and is difficult to diffuse in the collection portion. In this regard, for example, as shown in FIG. 3, if the control valve 43 is opened at the timing t6 when the reverse flow of the intake air begins to occur in the intake port and the intake manifold 20, the total length of the branch pipe and the intake port is long. However, it is possible to suppress the occurrence of the above-described problem caused by intake of intake manifold and intake port being drawn toward the cylinder immediately before the intake valve is closed.

  In short, a control valve is provided in the gas introduction passage to control the introduction of gas, and corresponds to the branch pipe closest to the connection between the gas introduction passage and the intake passage among the branch pipes of the intake manifold. What is necessary is just to make a control valve open in the predetermined period immediately after the intake valve of the cylinder to perform changes from a valve-opening state to a valve-closing state.

  In the above embodiment, the blow-by gas introduction device 4 that introduces the blow-by gas staying in the crankcase of the internal combustion engine into the intake passage 2 is illustrated as the gas introduction device of the internal combustion engine. However, the gas introduction device is not limited to this. It is not something that can be done.

  For example, in an internal combustion engine equipped with an evaporative fuel introduction device that introduces evaporative fuel staying in a fuel tank into an intake passage, the evaporative fuel is a gas introduction passage in a particular cylinder, that is, each branch pipe of the intake manifold. If a large number of cylinders corresponding to the branch pipes closest to the connection portion between the air intake and the intake passage are introduced to the cylinder, the air-fuel ratio varies from cylinder to cylinder. I am concerned that it will occur. In this regard, if the present invention is applied to an evaporative fuel introduction device that introduces evaporative fuel that stays in a fuel tank of an internal combustion engine into an intake passage, variations in air-fuel ratio among cylinders and fluctuations in engine rotation speed caused by the variation will occur Can be suppressed.

  Further, in an internal combustion engine equipped with an EGR gas introduction device that introduces exhaust gas from the internal combustion engine into the intake passage, the exhaust gas is a specific cylinder, that is, among each branch pipe of the intake manifold, the gas introduction passage and the intake passage. If a large amount of the exhaust gas is introduced into the cylinder corresponding to the branch pipe closest to the connecting portion, the exhaust amount introduced into the other cylinders cannot be sufficiently secured, and NOx in the entire internal combustion engine is reduced. The exhaust property will be worsened such that the amount of discharge increases. In this regard, if the present invention is applied to an EGR gas introduction device that introduces exhaust gas from an internal combustion engine into an intake passage, it is possible to suppress the deterioration of exhaust properties as described above.

  In short, it is provided with a gas introduction passage that is connected to the intake upstream side of each branch pipe of the intake manifold provided in the intake passage of the internal combustion engine having a plurality of cylinders and introduces a gas different from the intake air into the intake passage. I just need it.

The block diagram which showed the schematic structure about the blow-by gas introduction apparatus concerning embodiment of this invention. (A) Open / close state of an intake valve provided in the first cylinder, (b) Change rate of mass flow rate of intake air at an intake port connected to the first cylinder, (c) Open / close state of a control valve, crank angle The timing chart which showed the relationship with. (A) Open / close state of an intake valve provided in the first cylinder, (b) Change rate of mass flow rate of intake air at an intake port connected to the first cylinder, (c) Open / close state of a control valve, crank angle The timing chart which showed the relationship with. The block diagram which showed the schematic structure about the conventional blow-by gas introduction apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 2 ... Intake passage, 20 ... Intake manifold, 21A-21D ... Branch pipe, 22 ... Collecting part, 23 ... Throttle body, 24 ... Throttle valve, 4,104 ... Blow-by gas introduction apparatus, 41 ... Blow-by gas introduction passage, 42 ... Connection part, 43 ... control valve, 44 ... electronic control unit, 45 ... crank angle sensor.

Claims (6)

With a common gas inlet passage at each branch pipe that is connected to the intake upstream side of the branch pipes of an intake manifold provided in an intake passage of an internal combustion engine having a plurality of cylinders, separate from the intake through the gas introduction passage in the gas the gas introduction device for an internal combustion engine introduced into the intake passage,
A control valve provided in the gas introduction passage for controlling the introduction of the gas;
The control valve is in a closed state except for a specific valve opening period. During the specific valve opening period, a connection portion between the gas introduction passage and the intake passage is connected to each branch pipe of the intake manifold. A gas introduction device for an internal combustion engine, including a predetermined period immediately after an intake valve of a cylinder corresponding to a branch pipe at the closest position shifts from an open state to a closed state. The gas introduction device for an internal combustion engine according to claim 1,
A gas introduction device for an internal combustion engine, wherein when the control valve is opened during the predetermined period, the control valve is opened immediately before the intake valve is closed. The gas introduction device for an internal combustion engine according to claim 1 or 2,
The specific valve opening period further includes a predetermined period from immediately before to immediately after the intake valve shifts from the closed state to the opened state. The gas introduction device for an internal combustion engine according to any one of claims 1 to 3,
The gas introduction device for an internal combustion engine, wherein the gas introduction device is a blow-by gas introduction device for introducing blow-by gas staying in a crankcase of the internal combustion engine into an intake passage. The gas introduction device for an internal combustion engine according to any one of claims 1 to 4,
The gas introduction device for an internal combustion engine, wherein the gas introduction device is an evaporative fuel introduction device for introducing evaporative fuel staying in a fuel tank of the internal combustion engine into an intake passage. In the gas introducing device for an internal combustion engine according to any one of claims 1 to 5,
The gas introduction device for an internal combustion engine, wherein the gas introduction device is an EGR gas introduction device for introducing exhaust gas of the internal combustion engine into an intake passage.

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