JP2013241849A - Exhaust device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust device for an internal combustion engine capable of suppressing exhaust interference.SOLUTION: An exhaust device for an internal combustion engine 1 with in-line four-cylinders includes: an exhaust passage 21; a recirculation passage 41 that recirculates some exhaust gas in the exhaust passage into an intake passage; a recirculation valve 42 that opens and closes the recirculation passage; a cooler 43 that cools the exhaust gas recirculating into the recirculation passage; and a helmholtz type resonator 60 including the cooler as a volume chamber.

Description

  The present invention relates to an exhaust device for an internal combustion engine.

  Resonance pipe, resonance volume, and check valve are provided in the external EGR (exhaust gas recirculation) passage, exhaust pressure fluctuation is increased by the resonance effect, and exhaust gas flows into the intake system by the check valve. There is known an EGR device that enhances (Patent Document 1).

JP-A-1-177446

  However, there is a problem that if a sufficient resonator effect is obtained, the resonator becomes large, or the resonator effect is lowered when a sufficiently large resonator cannot be provided.

  The problem to be solved by the present invention is to provide an exhaust device for an internal combustion engine that can provide a sufficient resonator effect without increasing the size.

  The present invention provides a recirculation passage for recirculating a part of exhaust gas in an exhaust passage of an internal combustion engine including in-line four cylinders to an intake passage, a recirculation valve for opening and closing the recirculation passage, and a gas cooler. The above problem is solved by providing a Helmholtz resonator including a cooler as a volume chamber.

  According to the present invention, when the recirculation valve is closed, the recirculation passage including the gas cooler as a volume chamber becomes a Helmholtz resonator, and the sound velocity is lowered by the cooling effect and the pressure pulsation arrival time is delayed. The resonator effect can be realized with a small volume.

1 is a block diagram showing an internal combustion engine to which an exhaust device according to an embodiment of the present invention is applied. It is a schematic diagram which shows the exhaust apparatus which concerns on one embodiment of this invention. It is a figure which shows the recirculation channel | path which concerns on one embodiment of this invention. It is a schematic diagram which shows the exhaust apparatus which concerns on other embodiment of this invention. It is a schematic diagram which shows the exhaust apparatus which concerns on other embodiment of this invention. It is a schematic diagram which shows the exhaust apparatus which concerns on other embodiment of this invention. 1 is a perspective view showing an internal combustion engine to which an exhaust device according to an embodiment of the present invention is applied.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an in-line four-cylinder internal combustion engine 1 to which an exhaust system according to an embodiment of the present invention is applied. In an intake passage 11 of the internal combustion engine 1, an air filter 12 and an intake air flow rate are detected. An air flow meter 13 for controlling the intake air flow rate, a throttle valve 14 for controlling the intake air flow rate, and a collector 15 are provided. The internal combustion engine 1 to which the exhaust system according to the present invention can be applied is not limited as long as it includes in-line four cylinders, and may be a V-type eight cylinder internal combustion engine or the like.

  The throttle valve 14 is provided with a throttle sensor that detects the opening degree of the throttle valve 14 and a throttle valve control device that can control the opening degree of the first throttle valve 14 by an actuator such as a DC motor. . The throttle valve control device electronically controls the opening degree of the throttle valve 14 based on a drive signal from the control unit 50 so as to achieve a required torque calculated based on a driver's accelerator pedal operation amount or the like.

  A fuel injection valve 17 is provided facing the combustion chamber 16 of each cylinder of the internal combustion engine 1. The fuel injection valve 17 is driven to open by a drive pulse signal set in the control unit 50, and pressure is supplied from a fuel pump (not shown) and is controlled to a predetermined pressure by a pressure regulator (not shown). Inject directly into. Note that fuel may be injected into the fuel injection port instead of the direct injection type. The spark plug 20 is mounted facing the combustion chamber 16 of each cylinder, and ignites the intake air-fuel mixture based on an ignition signal from the control unit 50.

  On the other hand, exhaust purification catalysts 24 and 25 for purifying the exhaust are provided in the exhaust passage 21. The exhaust purification catalysts 24 and 25 oxidize carbon monoxide CO and hydrocarbon HC in the exhaust in the vicinity of stoichiometric (theoretical air-fuel ratio, λ = 1, air weight / fuel weight = 14.7), and nitrogen oxidation. It is possible to use a three-way catalyst that can purify exhaust gas by reducing product NOx, or an oxidation catalyst that oxidizes carbon monoxide CO and hydrocarbon HC in the exhaust gas. The exhaust purification catalyst 24 is provided in the vicinity of the internal combustion engine 1, while the exhaust purification catalyst 25 is provided on the floor of the vehicle body. Details of this part will be described later. In FIG. 1, reference numeral 23 denotes a muffler.

  The internal combustion engine 1 of the present embodiment includes an exhaust gas recirculation mechanism (EGR) 40 that recirculates exhaust gas downstream of the exhaust purification catalyst 24 to the intake passage 11 and performs intake air in a predetermined operating condition, for example, in a low load region. The exhaust gas is recirculated through the passage 11 to lower the exhaust gas temperature and improve the fuel consumption. On the other hand, the exhaust gas recirculation mechanism 40 is stopped, for example, in a low rotation / high load region other than the predetermined operating conditions.

  The exhaust gas recirculation mechanism 40 of this example is provided in the recirculation passage 41, which connects the exhaust passage 21 downstream of the exhaust purification catalyst 24 and the intake passage 11 downstream of the throttle valve 14, and the recirculation passage 41. A recirculation valve 42 that opens and closes to adjust the flow rate of the recirculated exhaust gas, and a cooler 43 that cools the recirculated exhaust gas. The opening / closing operation of the recirculation valve 42 is controlled by a control signal from the control unit 50. Further, the cooler 42 is a cooler having a heat exchange chamber inside the casing, and a refrigerant that cools the exhaust gas to be recirculated circulates and exhausts cooled by exchanging heat with the exhaust gas. The gas is recirculated to the intake passage 11.

  Next, the configuration of the exhaust passage 21 downstream from the cylinder of the main body of the internal combustion engine 1 will be described. FIG. 2 is a schematic diagram showing the configuration of the exhaust passage 21 according to an embodiment of the present invention. The internal combustion engine 1 includes four cylinders 31 to 34 arranged in series (two intake valves and two in each cylinder). 16-valve engine with two exhaust valves). That is, the first cylinder 31, the second cylinder 32, the third cylinder 33, and the fourth cylinder 34 are arranged in series from the left side to the right side in FIG. 2, and the first cylinder 31⇒the third cylinder 33⇒the fourth cylinder 34⇒. The second cylinder 32 is ignited in the order, and the first cylinder 31, the fourth cylinder 34, and the second cylinder 32, the third cylinder 33 are cylinders whose exhaust strokes are not continuous with each other.

  Two pairs of exhaust ports are formed at positions corresponding to the cylinders 31 to 34 on the back surface of the cylinder head of the internal combustion engine 1 (joint surface with the cylinder block). That is, two exhaust ports 211 are formed at a position corresponding to the first cylinder 31, two exhaust ports 212 are formed at a position corresponding to the second cylinder 32, and at a position corresponding to the third cylinder 33. Two exhaust ports 213 are formed, and two exhaust ports 214 are formed at positions corresponding to the fourth cylinder 34. Further, an exhaust branch pipe 215 is connected to the outlet end of the exhaust port 211, an exhaust branch pipe 216 is connected to the outlet end of the exhaust port 212, and an exhaust branch pipe 217 is connected to the outlet end of the exhaust port 213. An exhaust branch pipe 218 is connected to the outlet end of the exhaust port 214.

  The exhaust branch pipe 216 and the exhaust branch pipe 217 gather in one first exhaust passage 219 immediately after the outlet of the cylinder head, and one flow path of the exhaust purification catalyst 24 is connected thereto. Further, the exhaust branch pipe 215 and the exhaust branch pipe 218 also gather in one second exhaust passage 220 immediately after the outlet of the cylinder head, and the other flow path of the exhaust purification catalyst 24 is connected thereto. In the exhaust purification catalyst 24 shown in the figure, the internal flow path is divided into left and right two, the first exhaust passage 219 is connected to the left flow path, and the second exhaust passage 220 is connected to the right flow path. Has been. The first exhaust passage 219 and the second exhaust passage 220 hold a dual length as it is at a predetermined length on the downstream side of the exhaust purification catalyst 24, and then gather into one third exhaust passage 221. A further exhaust purification catalyst 25 is provided.

  In this example, the base end of the recirculation passage 41 is connected to the third exhaust passage 221 in which the first exhaust passage 219 and the second exhaust passage 220 are gathered together on the downstream side of the exhaust purification catalyst 24.

FIG. 3 is a diagram showing the configuration of the recirculation passage 41 of the present example. The recirculation passage 41 is provided with a recirculation valve 42 and a cooler 43, but also functions as a Helmholtz resonator 60. The Helmholtz resonator is a resonator that uses the principle of Helmholtz resonance, and has a function of reducing exhaust interference (exhaust gas pulsation) that occurs during exhaust. For this reason, it has a sealed volume chamber and a resonance tube part that guides exhaust gas to this, and the resonance (silence) frequency f of the Helmholtz resonator is f = [c / 2π] [S / {V1 (L + 1.6a). )}] ^1/2 . Here, the speed of sound c, the cross-sectional area S of the resonance tube portion, the radius a of the cross section of the resonance tube portion, the length L of the resonance tube portion, and the volume V1 of the volume chamber.

  In the example shown in FIG. 3, a part of the recirculation passage 41 from the connection portion P <b> 1 to the exhaust passage 21 to the connection portion P <b> 2 to the cooler 43 in the recirculation passage 41 is the first recirculation passage 411 and the second recirculation passage 411. The recirculation passage 412 has a double pipe structure. One end of the first recirculation passage 411 is connected to the cooler 43, and a part of the second recirculation passage 412 is inserted in an airtight manner on the other end side. The second recirculation passage 412 is more than the first recirculation passage. A small-diameter passage, one end of which is connected to the exhaust passage 21 and the other end is hermetically inserted into the second recirculation passage 411. The Helmholtz resonator 60 of this example is configured such that the internal space of the cooler 43 and the first recirculation passage 411 are a volume chamber (volume V1), and the second recirculation passage 412 is a resonance tube portion (tube length L). Has been.

  By forming a part of the first recirculation passage 411 and the second recirculation passage 412 as shown in FIG. 3 into a double pipe structure, the first recirculation passage 411 is also used as a volume chamber in addition to the cooler 43. Since it can function, the settable range of the resonance frequency is widened, and the resonator effect can be sufficiently exerted even with a compact shape. Further, the resonance frequency can be set to a desired value by adjusting the length of the double tube portion.

  The Helmholtz resonator 60 of the present invention is not limited to the example shown in FIG. 3, and may be a single recirculation passage instead of the first recirculation passage 411 and the second recirculation passage 412. In this case, the inside of the cooler 43 becomes the volume chamber of the Helmholtz resonator, and one recirculation passage becomes the resonance tube portion.

  Further, when the recirculation passage 41 is arranged around the actual main body of the internal combustion engine 1, a bellows portion (or spherical joint) 44 may be provided in the middle of the recirculation passage 41 as shown in FIG. Although vibrations are great on the downstream side of the exhaust passage 21, if the bellows portion 44 is provided in the recirculation passage 41, vibration of the exhaust passage 21 can be absorbed by the bellows portion 44. Therefore, the recirculation passage 41 can be connected to the downstream side of the exhaust passage 21 where the vibration is large. As a result, the dual lengths of the first exhaust passage 219 and the second exhaust passage 220 can be set to be sufficiently long. The effect of suppressing exhaust interference in the rotation region is great.

  As described above, according to the exhaust system of this example, when the recirculation valve 42 is closed (EGR function is stopped), the recirculation passage 41 functions as the Helmholtz resonator 60. Exhaust interference caused by blowdown from an adjacent cylinder specific to the engine is reduced, and the amount of exhaust gas remaining in the cylinder can be reduced. In addition, since the cooler 43 is used as a volume chamber, the sound velocity c decreases and the pressure pulsation arrival time is delayed by cooling the gas, so that the resonator effect can be realized even with a small volume or a short pipeline. it can.

  In the embodiment shown in FIG. 2, the recirculation passage 41 is connected to the third exhaust passage 221, but may be connected to the first exhaust passage 219 or the second exhaust passage 220. FIG. 4 is a schematic view showing an embodiment in which the recirculation passage 41 is connected to the first exhaust passage 219 in the exhaust device according to the present invention. Since other configurations are the same as those of the embodiment shown in FIG. 2, the description thereof is incorporated herein and omitted. Note that the total length of the exhaust passage from the exhaust port to the point where the first exhaust passage 219 and the second exhaust passage 220 join the third exhaust passage 221, that is, regarding the two cylinders closer to the center, Regarding the total length of the lengths of the exhaust branch pipes 216 and 217 connected to the second cylinder 32 and the third cylinder 33 and the length of the first exhaust passage 219 or the outer two cylinders, the first cylinder 31, If the total length of the exhaust branch pipes 215 and 218 connected to the fourth cylinder 34 and the length of the second exhaust passage 220 is called the length of the dual portion, it corresponds to the two cylinders closer to the center. On the first exhaust passage 219 side, the length of the dual portion is shorter than that on the second exhaust passage 220 side corresponding to the outer two cylinders.

As shown in the figure, in the exhaust passage from each cylinder, the length L1 from the cylinder block to the exhaust purification catalyst is set to be approximately equal, but the exhaust gas is exhausted after the two exhaust branch pipes gather together. The lengths L ₂₁₉ and L ₂₂₀ to the purification catalyst may be different. For example, in an in-line four-cylinder internal combustion engine, the first exhaust passage 219 that gathers exhaust passages from the second cylinder 32 and the third cylinder 33 gathers exhaust passages from the first cylinder 31 and the fourth cylinder 34. As a result, the length of the exhaust branch pipes 216 and 217 on the first exhaust passage 219 side is shortened, and consequently the length of the dual portion which is the total length is shortened. There are many. However, if the length of the dual portion, which is the total length in this way, is short, exhaust interference particularly in the low rotation range becomes large. By connecting the passage 41, exhaust interference is suppressed.

  FIG. 5 is a schematic view showing still another embodiment. In place of the exhaust purification catalyst 24 of FIG. 4, two independent exhaust purification catalysts 24A and 24B are provided in the first exhaust passage 219 and the second exhaust passage 220, respectively. It is the provided embodiment. In the embodiment shown in FIG. 2 and FIG. 4 described above, the inside of one exhaust purification catalyst 24 is divided into two regions. However, as shown in FIG. 5, two exhaust purification catalysts 24A, 24B independent of each housing are provided. May be used.

  FIG. 6 is a schematic view showing still another embodiment, and the configuration from the cylinder head to the exhaust purification catalysts 24A and 24B is different from the embodiment of FIG. That is, in the internal combustion engine 1 of FIG. 6, the exhaust port 212 from the second cylinder 32 and the exhaust port 213 from the third cylinder 33 are gathered into one exhaust port in the cylinder head, and from here to the exhaust purification catalyst 24A. Is the first exhaust passage 219. By doing so, the configuration from the internal combustion engine 1 to the exhaust purification catalyst 24 is simplified, and a more compact exhaust device is obtained. Even in such a case, exhaust interference can be effectively suppressed by connecting the recirculation passage 41 to the first exhaust passage 219 on the side where the length of the dual portion is short.

  The bellows portion 44 corresponds to an angle adjustment mechanism according to the present invention.

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 11 ... Intake passage 12 ... Air filter 13 ... Air flow meter 14 ... Throttle valve 15 ... Collector 16 ... Combustion chamber 17 ... Fuel injection valve 20 ... Spark plug 21 ... Exhaust passage 211, 212, 213, 214 ... Exhaust port 215, 216, 217, 218 ... exhaust branch pipe 219 ... first exhaust passage 220 ... second exhaust passage 221 ... third exhaust passage 23 ... muffler 24 ... exhaust purification catalyst 25 ... exhaust purification catalyst 31 ... first cylinder 32 ... first cylinder 2 cylinder 33 ... 3rd cylinder 34 ... 4th cylinder 40 ... exhaust gas recirculation mechanism 41 ... recirculation passage 42 ... recirculation valve 43 ... cooler 44 ... bellows part (angle adjustment mechanism)
50 ... Control unit 60 ... Helmholtz resonator

Claims (9)

An exhaust passage,
A recirculation passage for recirculating a part of the exhaust gas in the exhaust passage to the intake passage;
A recirculation valve for opening and closing the recirculation passage;
A cooler for cooling the exhaust gas recirculated to the recirculation passage;
An exhaust system for an internal combustion engine, comprising: a Helmholtz resonator including the cooler as a volume chamber. The exhaust passage is provided with an exhaust purification catalyst,
The exhaust device for an internal combustion engine according to claim 1, wherein an end of the recirculation passage on the exhaust passage side is connected downstream of the exhaust purification catalyst. The internal combustion engine is an in-line four-cylinder internal combustion engine,
The exhaust passage includes a first exhaust passage in which two of the four exhaust ports of the internal combustion engine are gathered into one, a second exhaust passage in which the other two exhaust ports are gathered into one, and A first exhaust passage and a third exhaust passage in which the second exhaust passage is assembled into one,
3. The exhaust device for an internal combustion engine according to claim 1, wherein an end portion of the recirculation passage on an exhaust passage side is connected to the third exhaust passage. The internal combustion engine is an in-line four-cylinder internal combustion engine,
The exhaust passage includes a first exhaust passage in which two of the four exhaust ports of the internal combustion engine are gathered into one, a second exhaust passage in which the other two exhaust ports are gathered into one, and A first exhaust passage and a third exhaust passage in which the second exhaust passage is assembled into one,
The total length of the exhaust passage from the exhaust port of the internal combustion engine to the point where the first exhaust passage and the second exhaust passage merge with the third exhaust passage is greater than that of the second exhaust passage. The aisle side is short,
2. The exhaust system for an internal combustion engine according to claim 1, wherein an end portion of the recirculation passage on an exhaust passage side is connected to the first exhaust passage. A first exhaust purification catalyst is provided in the first exhaust passage; a second exhaust purification catalyst is provided in the second exhaust passage;
5. The exhaust device for an internal combustion engine according to claim 4, wherein an end portion of the recirculation passage on the exhaust passage side is connected to a downstream side of the first exhaust purification catalyst in the first exhaust passage.   In the first exhaust passage, two exhaust ports in the central portion where the exhaust stroke is not continuous among the four exhaust ports of the internal combustion engine are gathered together in the cylinder head, and the third exhaust gas is discharged from the cylinder head outlet end. The exhaust system for an internal combustion engine according to any one of claims 3 to 5, wherein the exhaust system is constituted by one exhaust branch pipe up to the passage.   The Helmholtz resonator is configured such that a resonance pipe portion is formed from a connection portion of the recirculation passage to the exhaust passage to a connection portion of the cooler, and an internal space of the cooler is a volume chamber. The exhaust device for an internal combustion engine according to any one of claims 1 to 6. Among the recirculation passages, the recirculation passage from the connection portion with the exhaust passage to the connection portion with the cooler is:
A part of the other end side of the first recirculation passage, one end of which is connected to the cooler;
One end is connected to the exhaust passage, and is configured in a double pipe structure that overlaps with a part on the other end side of the second recirculation passage having a smaller diameter than the first recirculation passage,
The Helmholtz resonator is configured such that the internal space of the cooler and the first recirculation passage are volume chambers, and the second recirculation passage is a resonance tube portion. 2. An exhaust system for an internal combustion engine according to 1.   The exhaust system for an internal combustion engine according to any one of claims 1 to 8, wherein an angle adjustment mechanism that makes the angle of the recirculation passage variable is provided in the recirculation passage.

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