JP2014070530A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability of a sensing value by agitating a flow of exhaust gas without complicating a structure in an internal combustion engine having a catalyst with a sensor and an EGR device.SOLUTION: An EGR pipe 10 is connected to a portion of an exhaust pipe 5 on an upper stream side than an A/F sensor while one end thereof enters inside the exhaust pipe 5. One end 10a of the EGR pipe 10 functions as a mixing member for agitating a flow of exhaust gas, and therefore, the exhaust gas can be mixed so that a component of the exhaust gas becomes uniform without complicating the structure. As a result, reliability of a detection value of the A/F sensor can be improved, and also a function of a catalyst can be improved.

Description

  The present invention relates to an internal combustion engine having an exhaust gas purification catalyst and an EGR device in an exhaust system.

  In recent internal combustion engines (especially gasoline engines), a catalyst (three-way catalyst) is inserted in an exhaust system in order to purify exhaust gas. Generally, the catalyst is separated into two, and the first catalyst (front catalyst) located on the upstream side is provided with an A / F sensor (air-fuel ratio sensor) as a set, and the second catalyst located on the downstream side. The catalyst (rear catalyst) is often provided with an O2 sensor (oxygen concentration sensor) as a set. The sensors are located on the upstream side of the respective catalysts. Therefore, the A / F sensor, the first catalyst, the O2 sensor, and the second catalyst are generally arranged in this order from the upstream.

  The air-fuel ratio, fuel injection amount, etc. are controlled based on the signal from the sensor, but in order to perform the control accurately, it is necessary to accurately reflect the exhaust gas component in the detected value of the sensor. It is desirable to touch the sensor in a state where exhaust gas is uniformly mixed. Therefore, in the patent document 1, the applicant of the present application aims to equalize the components by disturbing the flow of the exhaust gas by projecting a rod-shaped member inwardly in a portion upstream of the sensor in the exhaust passage. Disclosed.

  On the other hand, in recent internal combustion engines, an EGR device that recirculates a part of exhaust gas to the intake system using an EGR pipe for improving fuel efficiency and promoting exhaust gas purification is also widespread, and means for connecting the EGR pipe to the exhaust passage Patent Document 2 describes that an outward tube portion is formed in the exhaust passage, and an EGR pipe is inserted and fixed in the outward tube portion.

JP 2012-77615 A JP 2005-106014 A

  When the configuration of Patent Document 1 is adopted, the exhaust gas can be brought into contact with the sensor in a uniformly mixed state and can be brought into contact with the catalyst in a uniformly mixed state. Therefore, the problem is that the structure becomes complicated and the cost increases.

  In addition, since the EGR gas contains moisture, it may agglomerate inside the EGR pipe after the engine is stopped. However, in the configuration in which the EGR pipe protrudes only outside the exhaust passage as in Patent Document 2. The water aggregated in the EGR pipe may flow into the inner surface of the exhaust pipe along the inner surface of the EGR pipe, but the aggregated water often contains a component that promotes corrosion. However, there is a risk that the exhaust pipe may be corroded and the durability of the exhaust pipe may be reduced due to the corrosion of the exhaust pipe.

  The present invention has been made in view of the present situation, and aims to simplify the structure and reduce the cost while securing the same effect as that of Patent Document 1.

  The present invention has been completed by paying attention to the EGR pipe. That is, the present invention relates to an internal combustion engine in which an exhaust passage is inserted with a catalyst in a set with a sensor in a state where the sensor is arranged on the upstream side, and on the upstream side of the sensor in the exhaust passage, The EGR pipe is connected in a state in which one end thereof enters the inside of the exhaust passage.

  According to the present invention, since one end portion of the EGR pipe enters the inside of the exhaust passage, the exhaust gas flowing inside the exhaust passage strikes the end portion of the EGR pipe and is disturbed. The sensor can be touched in a uniform state. As a result, the reliability of the detection value of the sensor can be increased and control can be performed accurately, and as a result, fuel consumption can be improved. Further, since the exhaust gas can be brought into contact with the catalyst in a state where the components are uniform, the exhaust gas can be purified evenly by the catalyst unit, and the purification performance can be improved.

  And since the EGR pipe which comprises an EGR apparatus is used and the disturbance effect | action is provided to the flow of exhaust gas, cost can be suppressed compared with the case where a new member is provided. Further, even if moisture condenses inside the EGR pipe and flows toward the exhaust passage, the moisture is moved from the end of the EGR pipe to the space of the exhaust passage by the wind pressure of the exhaust gas flowing through the exhaust passage during operation of the engine. Since it is blown off and vaporizes, corrosion of the exhaust pipe is not promoted. Also, if water condenses inside the EGR pipe after the engine is stopped, the water drips down from the tip of the EGR pipe to the catalyst, and the exhaust pipe In this case, corrosion of the exhaust pipe is not promoted because it does not flow along the inner surface.

  The exhaust pipe repeatedly expands and contracts by transferring heat accompanying the start and stop of the engine, and distortion due to the expansion and contraction of the exhaust pipe also acts on the EGR pipe. In this case, since the end portion of the EGR pipe is connected to the exhaust pipe in Patent Document 2, stress concentrates on the end of the EGR pipe due to the expansion of the exhaust pipe, so that there is a problem that the EGR pipe is easily torn.

  On the other hand, in the present invention, since the EGR pipe is connected to the exhaust pipe at a position before the tip, even if the EGR pipe expands due to expansion of the exhaust pipe, the EGR pipe does not tear. Therefore, in this invention, the attachment intensity | strength and durability of an EGR pipe can also be improved.

(A) is a typical principal part top view of an internal combustion engine, (B) is BB sectional drawing of (A). (A) is IIA-IIA sectional view taken on the line of FIG. 1 (B), (B)-(D) are the other examples of an EGR pipe attachment structure. (A) (B) is another example figure of an EGR pipe attachment structure.

  Next, an embodiment of the present invention will be described with reference to the drawings. The internal combustion engine has a cylinder block 1 and a cylinder head 2 fixed to the upper surface thereof, and an exhaust manifold 3 is fixed to one side surface 2 a of the cylinder head 2. Although not shown, an intake manifold is fixed to the other side surface 2 b of the cylinder head 3. The internal combustion engine of the present embodiment is a three-cylinder type in which three cylinder bores 4 are formed. Therefore, the exhaust manifold 3 has three branch pipes 3a, and a gathering portion where the three branch pipes 3a gather. Is connected to the exhaust pipe 4.

  A first catalyst 6 located near the exhaust manifold 3 and a second catalyst 7 located downstream thereof are inserted into the exhaust pipe 5. An A / F sensor 8 is used as a set for the first catalyst 6, and this A / F sensor 8 is connected to the exhaust pipe 5 on the upstream side of the first catalyst 6 (collection part of the exhaust manifold 3). 3b may be provided). An O2 sensor 9 is used for the second catalyst 7 as a set, and the O2 sensor 8 is provided between the first catalyst 6 and the second catalyst 7 (directly downstream of the first catalyst 6).

  The exhaust manifold 3 and the exhaust pipe 5 constitute an exhaust passage. In the present embodiment, a part of the exhaust pipe 5 is integrated with the catalysts 5 and 6 and connected by flange connection.

  One end of the EGR pipe 10 is connected to a portion of the exhaust pipe 5 between the A / F sensor 8 and the first catalyst 6. The other end of the EGR pipe 10 is connected to one side 2a of the cylinder head 2. The cylinder head 2 is formed with an EGR passage 11 opened to the other side 2b. An EGR valve 12 communicating with the EGR passage 11 is fixed. The outlet port of the EGR valve 12 is connected to the intake system.

  As shown by the alternate long and short dash line in FIG. 1B, the EGR pipe 10 can be connected between the first catalyst 6 and the O 2 sensor 9. Alternatively, it is also possible to connect the EGR pipes 10 at two locations, the upstream side of the A / F sensor 8 and the upstream side of the O2 sensor 9, and collect the two EGR pipes 10 and connect them to the cylinder head 2. is there.

  The connection structure of the EGR pipe 10 to the exhaust pipe 5 is shown in FIG. That is, a burring portion 13 projecting outward is formed in the exhaust pipe 5, and one end portion of the EGR pipe 10 is inserted into the burring portion 13 and fixed by welding such as brazing. The burring portion 13 may protrude inward, but it is preferable to protrude outward from the viewpoint of avoiding the influence of heat as much as possible.

  One end portion 10 a of the EGR pipe 10 has a large diameter portion and protrudes into the exhaust pipe 5. The dimension in which the one end portion 10a of the EGR pipe 10 enters the exhaust pipe 5 can be arbitrarily set. In the illustrated embodiment, the entrance dimension is smaller than the radius of the exhaust pipe 5, but the entrance dimension can be set to about the radius of the exhaust pipe 5 or can be set to an entrance dimension larger than the radius.

  Since the exhaust gas passing through the inside of the exhaust pipe 5 has the fastest flow velocity at the center of the exhaust pipe 5, if one end 10 a of the EGR pipe 10 is extended to a position beyond the center of the exhaust pipe 5, the exhaust gas It can be said that the disturbance effect of can be further ensured.

  As described above, since the one end portion 10a of the EGR pipe 10 enters the inside of the exhaust pipe 5, the exhaust gas passing through the inside of the exhaust pipe 5 is disturbed by the one end portion 10a of the EGR pipe 10 to be uniform. It mixes with the state. For this reason, the reliability of the detection value by the first sensor 8 can be increased, the engine control can be made appropriate, and the fuel consumption can be improved and the exhaust gas purification performance can be improved. Moreover, since harmful components are evenly dispersed, the purification efficiency of the first catalyst 6 can be improved, and the purification performance can be improved in this respect as well.

  Further, since the EGR pipe 10 has entered the exhaust pipe 5, the one end portion 10 a of the EGR pipe 10 comes into contact with the entire inner periphery of the burring portion 13 of the exhaust pipe 5. Since the support strength of 10 can be improved, the attachment strength of the EGR pipe 10 can also be improved. Further, since the EGR pipe 10 is fixed to the exhaust pipe 5 at a portion inside the front end surface, even if the exhaust pipe 5 is thermally expanded and the EGR pipe 10 is expanded, the EGR pipe 10 is not extended from the front end. There is no such thing as tearing. For this reason, the attachment strength and durability of the EGR pipe 10 can be improved.

  When the one end portion 10a of the EGR pipe 10 is set to have a large diameter as in the present embodiment, the disturbance effect of the exhaust gas flow can be increased and the exhaust gas components can be more evenly distributed. There is an advantage that exhaust gas can be taken in efficiently. Further, since the area of the joint with the exhaust pipe 5 is increased, there is an advantage that the mounting strength can be improved.

  Another example of the structure for attaching the EGR pipe 10 to the exhaust pipe 5 is shown in FIG. In the example shown in FIG. 2B, another joint 14 is connected to the EGR pipe 10, the joint 14 is fixed to the exhaust pipe 5, and the joint 14 is made to enter the exhaust pipe 5. . In other words, in this embodiment, the one end portion 10a of the EGR pipe 10 is constituted by a joint 14 which is a separate member. The joint has a flange 14a, and the flange 14a is fixed to the outer surface of the exhaust pipe 5 by welding.

  In this embodiment, the EGR pipe 10 does not need to be specially processed. On the other hand, since the joint 14 is easily processed, the workability of processing and assembly can be improved as a whole. Moreover, since the joint 14 can be made into a sturdy structure, it is also possible to improve the attachment strength of the EGR pipe 10. Furthermore, the heat resistance can be improved by forming the joint 14 from a heat-resistant material.

  In the embodiment shown in FIGS. 2C and 2D, a small hole 15 is formed in one end portion 10 a of the EGR pipe 10. In the embodiment of (C), the hole is open in the axial direction of the exhaust pipe 5, and in the embodiment of (C), the small hole 15 is open in the direction crossing the axis of the exhaust pipe 5. In any case, since the exhaust gas enters the small holes 15, the disturbance of the flow of the exhaust gas is promoted and the uniformization can be promoted. Also, exhaust gas intake performance is improved.

  The number and one of the small holes 15 can be set arbitrarily. As shown in (C), it is possible to extend the one end 10a to form a small hole 15 that opens in both the axial direction and the radial direction of the exhaust pipe 5. Further, the small hole 15 may be opened in a direction inclined with respect to the axial center of the exhaust pipe 5.

  In the embodiment shown in FIG. 3A, one end portion 10a that has entered the exhaust pipe 5 of the EGR pipe 10 is formed in a tapered shape, and a horizontally long slot 16 is formed in the one end portion 10a. ing. Although the long hole 16 is vacant in the transverse direction perpendicular to the axis of the exhaust pipe 5, it may be opened in the axial direction of the exhaust pipe 5. In this embodiment, since the EGR pipe 10 can deeply enter the exhaust pipe 5 while improving the exhaust gas flow resistance, it can be expected that the disturbance effect of the exhaust gas flow can be improved.

  Further, since the exhaust gas is guided so as to flow from the root of the one end portion 10a of the EGR pipe 10 toward the tip, it can be said that the disturbance effect of the exhaust gas is further enhanced. Further, when the long hole 16 exists in the one end portion 10a of the EGR pipe 10, the exhaust gas is subjected to an action of stopping at the position of the long hole 16, but the long hole 16 extends long in the axial direction. This causes a wide range of actions such as pushing the exhaust gas sideways. Thereby, a higher disturbing effect can be expected.

  In the example shown in FIG. 3B, one end portion 10a of the EGR pipe 10 is cut obliquely, and the cut surface is made to oppose the flow direction of the exhaust pipe 5. In this embodiment, the exhaust gas that hits the cut surface of the one end portion 10a is largely changed in the horizontal direction, so that the disturbance effect of the exhaust gas can be expected to be significantly increased. In addition, EGR gas uptake is improved.

  As mentioned above, although embodiment of this invention was described, this invention can be variously embodied other than said embodiment.

  The present invention is effective when applied to an internal combustion engine such as a gasoline engine. Therefore, it can be used industrially. For example, it is possible to incline the one end portion of the EGR pipe that has entered the exhaust pipe so that the tip thereof is downstream of the exhaust gas flow (inclined in the opposite direction). ).

2 Cylinder head 3 Exhaust manifold 3b Collecting part 5 Exhaust pipe constituting exhaust passage 6 First catalyst 7 Second catalyst 8 A / F sensor (front sensor)
9 O2 sensor (rear sensor)
10 EGR pipe 13 Burring part 14 Joint 15 Small hole 16 Long hole

Claims (1)

A catalyst set in a sensor is inserted in the exhaust passage in a state where the sensor is arranged on the upstream side, and an EGR pipe is connected to one end of the exhaust passage on the upstream side of the sensor. Connected in the state of entering the inside of the exhaust passage,
Internal combustion engine.

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