JP6700823B2 - Gas recirculation device - Google Patents

Description

  The present invention relates to a gas recirculation device that supplies exhaust gas to an intake system.

  A gas recirculation device that supplies a part of exhaust gas to the intake system by connecting an exhaust system and an intake system of the engine has been proposed (see Patent Document 1). As described above, by mixing the exhaust gas with the intake air flowing toward the combustion chamber, the combustion temperature can be lowered to improve the exhaust gas purification performance, and the pump loss can be reduced to improve the fuel efficiency performance. ..

Japanese Utility Model Laid-Open No. 3-114563

  By the way, in order to further improve the fuel efficiency performance and exhaust gas purification performance of the engine, it is necessary to evenly distribute the exhaust gas to the intake ports of the engine. Therefore, in the gas recirculation device, it is required to mix the intake air and the exhaust gas well.

  An object of the present invention is to mix intake air and exhaust gas well.

A gas recirculation device of the present invention is a gas recirculation device that supplies exhaust gas from an exhaust system of an engine to an intake system, and an intake manifold that is provided in the intake system and distributes intake air to each intake port of the engine. A throttle body provided in the intake system for adjusting a flow rate of intake air; an adapter provided in the intake system and sandwiched between the intake manifold and the throttle body; and an exhaust system and the adapter. A gas supply path connected to the exhaust system for supplying exhaust gas to the adapter, the gas supply path having a first supply pipe connected to the exhaust system and a second supply pipe connected to the adapter; A cross-sectional area of an extension flow passage, which is provided with a supply pipe and a cylindrical expansion chamber provided between the first supply pipe and the second supply pipe, and is defined by the second expansion chamber. much larger than the cross-sectional area of the discharge passage which is defined in the feed pipe, said a first supply pipe opening of the introduction channel which is defined in the discharge passage is partitioned into the second supply the pipe And the openings are arranged concentrically .

  According to the present invention, the gas supply passage includes an introduction passage connected to the exhaust system, a discharge passage connected to the intake system, and an expansion passage provided between the introduction passage and the discharge passage. , And the cross-sectional area of the expansion channel is larger than the cross-sectional area of the discharge channel. Thereby, the intake air can be moved in and out of the expansion flow path, and the intake air and the exhaust gas can be mixed well.

It is a schematic diagram showing an engine provided with a gas recirculation device which is one embodiment of the present invention. It is sectional drawing which shows some intake systems and an exhaust gas recirculation system along the AA line of FIG. It is a perspective view showing a part of intake system and exhaust gas recirculation system. 4A is a sectional view showing a part of the EGR adapter and the exhaust gas recirculation system, FIG. 4B is a sectional view taken along the line BB of FIG. 4A, and FIG. 4D is a cross-sectional view taken along the line CC of FIG. 4A, and FIG. 4D is a cross-sectional view taken along the line D-D of FIG. (A) And (b) is the figure which showed the mixing process of intake air and EGR gas by light and shade. (A) And (b) is the figure which showed the mixing process of intake air and EGR gas by light and shade. It is the figure which showed simply the flow of the intake air and EGR gas in the expansion chamber. It is sectional drawing which shows the gas recirculation|reflux apparatus as a comparative example. FIG. 7 is a comparative diagram showing the EGR variation rates of the example and the comparative example in comparison. FIG. 8 is a comparison diagram showing the EGR variation rates of the example and the comparative example in comparison.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing an engine 11 including a gas recirculation device 10 according to an embodiment of the present invention. Although the illustrated engine 11 is a horizontally opposed engine, the engine 11 is not limited to this, and may be an in-line engine, a V-type engine, or the like.

  As shown in FIG. 1, the engine 11 has a cylinder block 13 having a plurality of cylinder bores 12, and a cylinder head 14 attached to the cylinder block 13. The cylinder head 14 has a plurality of intake ports 16 connected to an intake system 15, and a plurality of exhaust ports (not shown) connected to an exhaust system 17. The intake system 15 includes an intake duct 22, a throttle body 19, an EGR adapter 20, an intake manifold 21, and the like. The exhaust system 17 also includes an exhaust passage 24 configured by an exhaust pipe 23, an exhaust manifold (not shown), and the like. The intake air flowing through the intake passage 22 is distributed through the intake manifold 21 to each intake port 16 after the flow rate is adjusted via the throttle body 19, and is supplied from the intake port 16 to a combustion chamber (not shown). Then, the exhaust gas discharged from the combustion chamber is supplied to the exhaust passage 24 from an exhaust port (not shown), and is discharged to the outside through a catalyst converter (not shown) and a silencer.

In order to improve the fuel efficiency performance of the engine 11 and the exhaust gas purification performance, the engine 11 is provided with an exhaust gas recirculation system 30 that recirculates a part of the exhaust gas to the intake system 15. The exhaust gas recirculation system 30 has an EGR supply passage 31 connected to the exhaust system 17 and the intake system 15. The EGR supply path 31 includes a supply pipe (first supply pipe) 32 connected to the exhaust pipe 23 of the exhaust system 17, a supply pipe (second supply pipe) 33 connected to the EGR adapter 20 of the intake system 15, and The expansion chamber 34 is provided between the supply pipe 32 and the supply pipe 33. Further, the supply pipe 32 of the EGR supply path 31 is provided with an EGR valve 35 that controls the flow rate of EGR gas. By configuring the exhaust gas recirculation system 30 in this way, a part of the exhaust gas is supplied as EGR gas to the intake system 15 via the EGR supply passage 31 and the EGR adapter 20, and the amount of EGR gas supplied is It is controlled by the EGR valve 35. The EGR is "Exhaust Gas Recirculation".

  FIG. 2 is a sectional view showing a part of the intake system 15 and the exhaust gas recirculation system 30 along the line AA of FIG. FIG. 3 is a perspective view showing a part of the intake system 15 and the exhaust gas recirculation system 30. As shown in FIGS. 2 and 3, the EGR adapter 20 is provided between the throttle body 19 located on the upstream side and the intake manifold 21 located on the downstream side. The EGR adapter 20 is formed with an intake passage 40 that guides intake air from the throttle body 19 to the intake manifold 21. In addition, the EGR adapter 20 is formed with a connection port 41 that opens in the intake passage 40 from the radial direction. An EGR supply path 31 including a supply pipe 33, an expansion chamber 34, and a supply pipe 32 is connected to the connection port 41 of the EGR adapter 20. Then, the EGR gas discharged from the supply pipe 33 of the EGR supply passage 31 to the intake passage 40 of the EGR adapter 20 is mixed with the intake air and distributed from the intake manifold 21 to each intake port 16. The throttle body 19 is a so-called butterfly type throttle body, and has a disc-shaped throttle valve 42 and a valve shaft 43 that supports the throttle valve 42. By driving the valve shaft 43 by a throttle motor (not shown), the throttle valve 42 can be rotated between the closed position shown by the solid line and the open position shown by the broken line. 44 can be opened and closed.

  FIG. 4A is a sectional view showing a part of the EGR adapter 20 and the exhaust gas recirculation system 30. 4B is a sectional view taken along the line BB of FIG. 4A, and FIG. 4C is a sectional view taken along the line C-C of FIG. 4A. FIG. 4D is a sectional view taken along the line D-D in FIG. As shown in FIGS. 4A to 4D, the EGR supply path (gas supply path) 31 for guiding the exhaust gas includes a supply pipe (introduction flow path) 32 connected to the exhaust system 17 and an intake system 15. And an expansion chamber (expansion flow path) 34 provided between the supply piping 32 and the supply piping 33. Here, the inner diameter D2 of the expansion chamber 34 is formed larger than the inner diameter D1 of the supply pipe 33, and the flow passage cross-sectional area (cross-sectional area) A2 of the expansion chamber 34 is the flow passage cross-sectional area (cross-sectional area) of the supply pipe 33. It is formed larger than A1. The inner diameter D2 of the expansion chamber 34 is formed larger than the inner diameter D3 of the supply pipe 33, and the flow passage cross-sectional area A2 of the expansion chamber 34 is larger than the flow passage cross-sectional area (cross-sectional area) A3 of the supply pipe 32. Has been formed. The flow passage cross-sectional areas A1, A2, A3 are the areas of the flow passage cross-sections orthogonal to the center lines of the supply pipe 33, the expansion chamber 34, and the supply pipe 32.

[Mixing status of intake air and EGR gas]
Next, the mixed state of intake air and EGR gas will be described. 5 and 6 are diagrams showing the mixing process of the intake air and the EGR gas by shading. 5 and 6, the high concentration region of EGR gas is shown in a dark color, and the low concentration region of EGR gas is shown in a light color. 5 and 6, the mixing process of intake air and EGR gas is shown in the order of FIG. 5(a), FIG. 5(b), FIG. 6(a), and FIG. 6(b). .. Note that in FIGS. 5 and 6, the throttle valve 42 is held in the open position. Further, FIG. 7 is a diagram simply showing the flow of intake air and EGR gas in the expansion chamber 34.

  As shown in FIGS. 5A and 5B, a part of the intake air flowing from the throttle body 19 into the EGR adapter 20 is sucked from the EGR adapter 20 into the expansion chamber 34. Further, as shown in FIGS. 5B and 6A, the intake air sucked into the expansion chamber 34 is agitated with the EGR gas in the expansion chamber 34, and then the EGR gas flows from the expansion chamber 34 into the EGR adapter. Released to 20. Then, as shown in FIGS. 6A and 6B, the mixed gas of the intake air and the EGR gas discharged from the expansion chamber 34 to the EGR adapter 20 is further mixed with the intake air in the intake manifold 21. And then supplied to each intake port 16. That is, as shown by arrows a1 to a3 in FIG. 7, a part of the intake air flowing from the throttle body 19 to the intake manifold 21 is sucked from the EGR adapter 20 into the expansion chamber 34 and agitated, and then, from the expansion chamber 34. It is released to the EGR adapter 20.

  As described above, since the intake air enters and leaves the expansion chamber 34 of the EGR supply path 31, mixing of the intake air and the EGR gas can be promoted, and the intake air and the EGR gas can be mixed well. As a result, it is possible to suppress variations in the proportion of EGR gas contained in the intake air (hereinafter referred to as the EGR content rate), and it is possible to supply the EGR gas to the intake ports 16 substantially evenly. .. Further, even when the EGR supply passage 31 is connected near the intake manifold 21, that is, even when the EGR gas is discharged to a position where the distance to the intake port 16 is short, the intake air and the EGR gas are separated from each other. It can be mixed well and supplied to the intake port 16. The opening 34a of the expansion chamber 34 on the intake system 15 side is rounded so that intake air can flow in and out of the expansion chamber 34.

  As described above, it is possible to promote the mixing of the intake air and the EGR gas by letting the intake air into and out of the expansion chamber 34 of the EGR supply passage 31. The reason is that the intake system 15 and the exhaust gas recirculation are used. Pulsations of system 30 are possible. That is, the intake air flowing through the intake system 15 and the EGR gas flowing through the exhaust gas recirculation system 30 periodically pulsate according to the crank angle of the engine 11. That is, the internal pressure of the EGR adapter 20 forming the intake system 15 and the internal pressure of the expansion chamber 34 forming the exhaust gas recirculation system 30 periodically fluctuate up and down according to the crank angle of the engine 11. .. Therefore, at a timing when the internal pressure of the EGR adapter 20 is higher than the internal pressure of the expansion chamber 34, a situation occurs in which intake air moves from the EGR adapter 20 to the expansion chamber 34, and the internal pressure of the expansion chamber 34 changes to the internal pressure of the EGR adapter 20. At a timing lower than the internal pressure, a situation occurs in which the intake air moves from the expansion chamber 34 to the EGR adapter 20. It is considered that the intake air flows in and out between the EGR adapter 20 and the expansion chamber 34 because such a fluctuation state of the internal pressure is periodically repeated.

  Further, as described above, the flow passage cross-sectional area A2 of the expansion chamber 34 is formed larger than the flow passage cross-sectional area A1 of the supply pipe 33. In this way, by expanding the flow passage cross-sectional area A2 of the expansion chamber 34, the capacity of the expansion chamber 34 can be secured, so that the suction force of the intake air in the expansion chamber 34 can be increased and at the same time, the expansion chamber 34 can have a larger suction force. The generation of vortices can be promoted. In other words, the flow passage cross-sectional area A1 of the supply pipe 33 is formed smaller than the flow passage cross-sectional area A2 of the expansion chamber 34. As described above, by reducing the flow passage cross-sectional area A1 of the supply pipe 33, the flow passage connecting the EGR adapter 20 and the expansion chamber 34 can be narrowed, so that the flow velocity of the intake air flowing in and out of the expansion chamber 34 can be reduced. Can be increased. As a result, mixing of the intake air and the EGR gas can be promoted, and the intake air and the EGR gas can be mixed well.

  Further, in order to promote the inflow and outflow of the intake air to and from the expansion chamber 34, it is desirable to provide the expansion chamber 34 on the downstream side of the EGR supply path 31, that is, in the vicinity of the EGR adapter 20 forming the intake system 15. Therefore, as shown in FIG. 2 and FIG. 4A, the supply pipe 33 of the EGR supply passage 31 is formed short, and the expansion chamber 34 is provided near the EGR adapter 20. In other words, since the expansion chamber 34 is provided in the vicinity of the EGR adapter 20, the volume of the discharge flow path partitioned by the supply pipe 33, that is, the volume is larger than the volume of the expansion flow path partitioned by the expansion chamber 34. Is also set small.

[Comparative example]
Next, the effect of the gas recirculation device 10 of the embodiment will be described by taking the gas recirculation device 100 as a comparative example as an example. Here, FIG. 8 is a cross-sectional view showing a gas recirculation device 100 as a comparative example. In FIG. 8, the same members as those shown in FIG. 2 are designated by the same reference numerals and the description thereof will be omitted. 9 and 10 are comparative diagrams showing the EGR variation rates of the example and the comparative example in comparison. FIG. 9 shows the EGR variation rate when the throttle valve 42 is held in the open position, and FIG. 10 shows the throttle valve 42 in the closed position (specifically, on the closed side with a valve opening of about 20 deg). The EGR variation rate in the state of being held at is shown. The EGR variation rate shown in FIGS. 9 and 10 is the difference between the EGR content rate of the entire intake air and the EGR content rate of the intake air supplied to each intake port 16. That is, the closer the EGR variation rate is to “0”, the more equal the EGR content rate of the intake air supplied to each intake port 16, and the more the EGR content rate variation is suppressed.

  As shown in FIG. 8, the gas recirculation device 100 as a comparative example has an EGR adapter 20 provided between the intake manifold 21 and the throttle body 19. To the connection port 41 of the EGR adapter 20, an EGR supply path 102 composed of a supply pipe 101 having a constant flow passage cross-sectional area is connected. As described above, when the supply pipe 101 is simply connected to the EGR adapter 20, it is difficult to let the intake air flow in and out of the supply pipe 101, and therefore, the mixing of the intake air and the EGR gas is promoted. Is difficult. Therefore, as shown in FIG. 9, in the gas recirculation device 100 of the comparative example, a large difference occurs in the EGR variation rate of each intake port 16. On the other hand, in the gas recirculation device 10 of the embodiment, as described above, since the expansion chamber 34 is provided in the EGR supply path 31, it is possible to promote the mixing of the intake air and the EGR gas, and each intake air The EGR variation rates of the ports 16 can be made close to each other.

  As shown in FIG. 10, when the throttle valve 42 is held in the closed position, the difference between the gas recirculation device 10 of the embodiment and the gas recirculation device 100 of the comparative example is less likely to appear. The reason is that when the throttle valve 42 is held in the closed position, the pressure of the EGR adapter 20 and the intake manifold 21 is likely to drop, so that it is difficult for intake air to move from the EGR adapter 20 to the expansion chamber 34. Conceivable. However, as shown in FIG. 10, the situation in which the throttle valve 42 is held in the closed position is a situation in which the intake air and the EGR gas are easily mixed because the flow velocity of the intake air decreases, so Also in the recirculation device 10, the EGR variation rates of the intake ports 16 approach each other.

  It is needless to say that the present invention is not limited to the above-mentioned embodiment and can be variously modified without departing from the scope of the invention. In the above description, the EGR supply passage 31 is connected to the EGR adapter 20, but the EGR supply passage 31 is not limited to this, and the EGR supply passage 31 is connected to other members constituting the intake system 15, such as the intake manifold 21. May be. Further, in the above description, a cylindrical expansion chamber is adopted as the expansion chamber 34 provided in the EGR supply path 31, but the expansion chamber is not limited to this, and it may have another shape such as a spherical shape or a prismatic shape. An expansion chamber may be adopted. Further, in the illustrated example, the supply pipes 32 and 33 and the expansion chamber 34 are configured by separate members, but the present invention is not limited to this, and the supply pipes 32 and 33 and the expansion chamber 34 are integrally formed. May be.

  In the illustrated example, the supply pipes 32 and 33 are connected to the center of the expansion chamber 34, but the present invention is not limited to this, and the supply pipes 32 and 33 may be connected to positions outside the center of the expansion chamber 34. good. Further, in the illustrated example, the flow passage cross-sectional areas of the supply pipe 32 and the supply pipe 33 are held substantially constant at each portion, but the present invention is not limited to this, and the flow of the supply pipe 32 or the supply pipe 33 is not limited to this. The road cross-sectional area may be changed depending on the part. In the illustrated example, the supply pipe 32 and the supply pipe 33 have the same flow passage cross-sectional area, but the present invention is not limited to this, and the supply pipe 32 and the supply pipe 33 have different flow passage cross-sectional areas. You may set it to the size. Further, in the illustrated example, the opening 34a on the intake system 15 side of the expansion chamber 34 is rounded, but the present invention is not limited to this, and the expansion chamber 34 and the other portion of the supply pipe 33 are rounded. Processing or chamfering may be performed.

10 gas recirculation device 11 engine 15 intake system 17 exhaust system 19 throttle body 21 intake manifold 31 EGR supply path (gas supply path)
32 supply piping (introduction flow path)
33 Supply pipe (release channel)
34 Expansion chamber (expansion flow path)
A1 Channel cross-sectional area (cross-sectional area)
A2 Channel cross-sectional area (cross-sectional area)
A3 flow path cross-sectional area (cross-sectional area)

Claims (4)

A gas recirculation device for supplying exhaust gas from an engine exhaust system to an intake system,
An intake manifold provided in the intake system for distributing intake air to each intake port of the engine;
A throttle body provided in the intake system for adjusting the flow rate of intake air;
An adapter provided in the intake system and sandwiched between the intake manifold and the throttle body,
A gas supply path connected to the exhaust system and the adapter, for supplying exhaust gas from the exhaust system to the adapter;
Have
The gas supply passage has a cylindrical shape provided between the first supply pipe connected to the exhaust system, the second supply pipe connected to the adapter , and the first supply pipe and the second supply pipe. And an expansion chamber of
The cross-sectional area of the expansion passage which is defined in the expansion chamber is much larger than the cross-sectional area of the discharge passage is partitioned into the second feed in the pipe,
A gas recirculation device , wherein an opening of the introduction flow path partitioned into the first supply pipe and an opening of the discharge flow path partitioned into the second supply pipe are concentrically arranged . The gas recirculation apparatus according to claim 1,
The gas recirculation device, wherein the cross-sectional area of the expansion flow path is larger than the cross-sectional area of the introduction flow path defined in the first supply pipe. The gas recirculation device according to claim 1 or 2,
The gas recirculation device, wherein the second supply pipe is connected to the intake system on the upstream side of the intake manifold. In the gas recirculation device according to any one of claims 1 to 3,
The adapter is
An intake passage for guiding intake air,
A connection port opening from the radial direction to the intake passage,
Have
Said second feed pipe, that is attached to the connection port, the gas recirculation system.