JP4544052B2 - Exhaust passage structure of internal combustion engine - Google Patents

Description

  The present invention relates to an exhaust passage structure of an internal combustion engine.

  Exhaust sensors such as a linear air-fuel ratio sensor and an O2 sensor are attached upstream and downstream of the catalytic converter. These exhaust sensors are activated by being heated to a high temperature by a built-in heater or exhaust gas, and can detect oxygen. This detection signal is used to control the air-fuel ratio of the exhaust gas so that the exhaust gas purification ability of the catalyst can be exhibited, and to determine the deterioration state of the catalyst.

  By the way, when the exhaust gas is cooled, condensed water is generated from the moisture contained in the exhaust gas. If this condensed water is applied to a sensor in a high temperature state, the sensor may be rapidly cooled to cause element cracking.

Therefore, conventionally, even if condensed water is generated, the exhaust passage is formed so that the condensed water does not accumulate upstream of the exhaust sensor but accumulates downstream of the exhaust sensor (see Patent Document 1).
Japanese Patent Laid-Open No. 11-2120

  By the way, recent research has confirmed that equalizing each branch pipe of the exhaust manifold leads to an increase in engine output and sound quality.

  However, in this way, there is a limit to where the branch pipe can be laid out in relation to other parts in the engine room, and as in Patent Document 1, the shape is such that condensed water does not accumulate upstream of the exhaust sensor. It may be difficult to do.

  The present invention has been made paying attention to such conventional problems, and prevents the condensate generated from the exhaust gas from scattering, and causes cracks in exhaust sensors such as linear air-fuel ratio sensors and O2 sensors. An object of the present invention is to provide an exhaust passage structure for an internal combustion engine that is not allowed to occur.

  The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected, it is not limited to this.

The present invention relates to a structure of an exhaust passage of an internal combustion engine, upstream of the exhaust passage from the exhaust sensor (40) for detecting an exhaust component is formed by bent residence portion condensed water stagnates generated from the exhaust gas And a hole (22b) formed in the staying portion through which the accumulated condensed water flows, an outer cylinder (22g) provided on the outer periphery of the exhaust passage, an outer peripheral wall of the exhaust passage, and the outer cylinder. is, possess the hole (22b) water reservoir for storing the run down condensed water from the (22 e), the second hole formed in the inner peripheral side of the bent portion of the exhaust passage (22j), the said The water vapor rising in the outer cylinder flows into the exhaust passage through the second hole (22j) .

  According to the present invention, the water reservoir chamber for storing the exhaust condensed water staying in the exhaust passage is provided. Since this water storage chamber is separated from the flow of exhaust gas, even if a large amount of exhaust gas flows due to the driver stepping on the accelerator immediately after the engine is started, the condensed water is not scattered. Therefore, it is possible to prevent the exhaust condensed water from getting into the exhaust sensor and destroying the sensor.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings.
(First embodiment)
FIG. 1 is a side view showing a left bank of a V-type 6-cylinder engine to which an exhaust passage structure for an internal combustion engine according to the present invention is applied.

  The exhaust manifold 20 is fixed to the cylinder head 11 of the engine 10 with mounting bolts 30.

  The exhaust manifold 20 has a # 2 cylinder branch pipe 21, a # 4 cylinder branch pipe 22, and a # 6 cylinder branch pipe 23 from the front side of the vehicle. The exhaust manifold 20 has an O2 sensor 40 attached to the gathering portion of these branch pipes 21 to 23, and further has a manifold catalyst 50 downstream thereof.

  The lengths of the branch pipes 21 to 23 are substantially the same in order to increase engine output and improve sound quality. For this reason, the # 2 cylinder branch pipe 21 has a substantially straight shape. However, the # 4 cylinder branch pipe 22 and the # 6 cylinder branch pipe 23 once extend downward in the front of the vehicle and then extend rearward of the other branch pipe. It has a shape to gather. For this reason, the # 4 cylinder branch pipe 22 and the # 6 cylinder branch pipe 23 are formed with bent portions 22a, 23a that are once lowered in the vertical direction and then raised. Since the bent portions 22a and 23a have such a shape, when condensed water is generated from the exhaust gas, the condensed water stays in the bent portions 22a and 23a. If the engine is started in this state, the condensate that has stayed may scatter and the O2 sensor 40 may get wet, causing damage to the sensor element. Therefore, in the present invention, a structure for preventing the condensate from splashing is provided in such an exhaust passage. A specific structure will be described with reference to FIG.

  FIG. 2 is a view showing the vicinity of the bent portion 22a of the # 4 cylinder branch pipe 22, and FIG. 2A is a view of the bent portion 22a of the # 4 cylinder branch pipe 22 cut along a plane including the vertical axis. FIG. 2B shows a BB cross section of FIG. Further, the flow direction of the exhaust gas is shown by white arrows in FIG.

  The branch pipe 22 has a hole 22b and a patch plate 22c.

  As shown in FIGS. 2A and 2B, the hole 22b is formed in a staying portion 22d that is substantially the lowest portion in the vertical direction of the bent portion 22a of the branch pipe 22 and in which the exhaust condensed water stays. The

  The patch plate 22 c is welded below the branch pipe 22. The entire circumference of the patch plate 22c is welded to the branch pipe 22 with a welding material 22f so that the exhaust gas flowing out from the hole 22b is not released to the atmosphere.

  A space between the branch pipe 22 and the patch plate 22c forms a water reservoir chamber 22e.

  The operation obtained by such a structure will be described.

  When the engine is stopped and the exhaust gas is cooled, condensed water is generated from the moisture in the exhaust gas. The condensed water flows along the inner wall surface of the branch pipe 22 to the bent portion 22a, and flows down from the hole 22b to the water storage chamber 22e and accumulates.

  Even when the engine is started thereafter, the water reservoir 22e is separated from the flow of the exhaust gas. Therefore, even if a large amount of exhaust gas flows due to the driver depressing the accelerator pedal immediately after starting the engine, the condensed water does not scatter.

  When the branch pipe 22 is warmed by the heat of the exhaust gas, the water stored in the water reservoir 22e becomes steam. When exhaust gas flows through the branch pipe 22, the pressure in the branch pipe decreases, so that water vapor is sucked out.

  Since the flow rate of the exhaust gas changes depending on the output of the engine and the pressure in the branch pipe changes, the exhaust gas enters and exits the water storage chamber 22e due to the pressure fluctuation, and all the water vapor is released.

  As described above, according to the present embodiment, the hole 22b is formed in the branch pipe 22, and the patch plate 22c is welded to form the water reservoir chamber 22e. Therefore, the condensed water generated from the exhaust gas is condensed into the water reservoir chamber 22e. Can be stored. Since the water storage chamber 22e is separated from the flow of exhaust gas, even if a large amount of exhaust gas flows due to the driver stepping on the accelerator immediately after starting the engine, the condensed water does not scatter. Therefore, it is possible to prevent the condensed water from getting into the exhaust sensor and destroying the sensor.

(Second Embodiment)
FIG. 3 is a view showing a second embodiment of the exhaust passage structure of the internal combustion engine according to the present invention, and FIG. 3 (A) is a view in which the bent portion 22a of the branch pipe 22 is cut along a plane including the vertical axis. FIG. 3B shows a BB cross section of FIG.

  In the following embodiments, the same reference numerals are given to the portions that perform the same functions as those of the above-described embodiments, and overlapping descriptions are omitted as appropriate.

  In the present embodiment, the branch wall in the vicinity of the bent portion 22a of the branch pipe 22 is bulged downward, and the patch plate 22c is welded to the inside thereof with a welding material 22f. A hole 22b is formed in the patch plate. The hole 22b is formed at the lowest position of the patch plate 22c. The branch pipe 22 is formed by welding an upper member and a lower member. After the patch plate 22c is welded to the lower member, the branch pipe 22 is formed.

  A space between the branch pipe 22 and the patch plate 22c forms a water reservoir chamber 22e.

  Also according to the present embodiment, the water reservoir chamber 22e is formed in the space between the branch pipe 22 and the patch plate 22c, so that the condensed water generated from the exhaust gas is stored in the water reservoir chamber 22e as in the first embodiment. Can do. Since the water reservoir 22e is separated from the flow of the exhaust gas, even if a large amount of exhaust gas flows due to the driver stepping on the accelerator immediately after the engine is started, the condensed water does not scatter. Therefore, it is possible to prevent the condensed water from getting into the exhaust sensor and destroying the sensor.

  Further, since the patch plate 22c is welded to the inside of the branch pipe 22, there is no possibility of exhaust gas being released into the atmosphere, so that it is not necessary to weld the entire circumference.

(Third embodiment)
FIG. 4 is a view showing a third embodiment of the exhaust passage structure of the internal combustion engine according to the present invention, and FIG. 4 (A) is a view in which the bent portion 22a of the branch pipe 22 is cut along a plane including the vertical axis. FIG. 4B shows a BB cross section of FIG.

  In this embodiment, the outer cylinder 22g is welded to the outer periphery of the bent portion 22a of the branch pipe 22 with the welding material 22f. The outer cylinder 22g is formed by welding the upper member and the lower member with a welding material 22h, and the inner periphery is welded to the outer wall of the branch pipe 22 with the welding material 22f. A hole 22 b is formed at the lowest position of the branch pipe 22. A hole 22j is formed in the inner peripheral wall of the bent portion 22a of the branch pipe 22.

  A space between the branch pipe 22 and the outer cylinder 22g forms a water reservoir chamber 22e.

  FIG. 5 is a diagram for explaining the effect of the third embodiment.

  When the engine is stopped and the exhaust gas is cooled, condensed water is generated from the moisture in the exhaust gas. The condensed water 1 flows along the inner wall surface of the branch pipe 22 to the bent portion 22a, and flows down from the hole 22b to the water reservoir chamber 22e and accumulates (FIG. 5A).

  Even when the engine is started thereafter, the water reservoir chamber 22e is separated from the flow of the exhaust gas. Therefore, even if a large amount of exhaust gas flows due to the driver depressing the accelerator immediately after the engine is started, the condensed water 1 does not scatter.

  When the branch pipe 22 is warmed by the heat of the exhaust gas, the water stored in the water reservoir 22e becomes steam and rises in the outer cylinder 22g.

  And the peeling area | region of the flow of exhaust gas is formed inside the bending part 22a of the branch pipe 22, and a pressure becomes low.

  Therefore, a part of the exhaust gas flowing through the branch pipe 22 flows from the hole 22b → the water reservoir 22e → the hole 22j → the branch pipe 22 as shown by the arrow in FIG. With this flow, the water vapor 2 also flows out to the branch pipe 22.

  Thus, according to the present embodiment, the outer cylinder 22g is welded to the outer periphery of the bent portion 22a of the branch pipe 22, and the hole 22b is formed at the lowest position of the branch pipe 22, and the bent portion of the branch pipe 22 is also formed. Since the hole 22j is formed in the inner peripheral wall of 22a, a part of the exhaust gas flowing through the branch pipe 22 flows through the hole 22b → the water reservoir 22e → the hole 22j → the branch pipe 22 as shown by an arrow in FIG. The steam 2 can flow out to the branch pipe 22 along with this flow.

(Fourth embodiment)
FIG. 6 is a view showing a fourth embodiment of the exhaust passage structure of the internal combustion engine according to the present invention.

  In the third embodiment, the outer cylinder 22g is welded to the outer periphery of the bent portion 22a of the branch pipe 22, but in this embodiment, the hole 22b and the hole 22j are connected by the pipe 22k. The pipe 22k once extends below the hole 22b, and then connects to the hole 22j along the outer periphery of the branch pipe 22.

  Even in this case, a part of the exhaust gas flowing through the branch pipe 22 flows in the order of the hole 22b → pipe 22k → hole 22j → branch pipe 22, so that water vapor can flow out to the branch pipe 22 along with this flow.

(Fifth embodiment)
FIG. 7 is a view showing a fifth embodiment of the exhaust passage structure of the internal combustion engine according to the present invention.

  The present embodiment is an example applied to the exhaust manifold 20 of a branch pipe 22 having a double structure composed of an outer tube 22p and an inner tube 22q. The outer tube 22p holds the inner tube 22q via the wire mesh ring 22r. This wire mesh ring 22r is formed by press-molding stainless steel wire steel into a ring shape and pressing it.

The outer tube 22p is thick, but the inner tube 22q is thin and has a small heat capacity. A heat insulating space is formed between the outer tube 22p and the inner tube 22q, and the temperature in the inner tube 22q is hardly lowered even when the engine is stopped, and the catalyst is activated in a short time when the engine is restarted.
The wire mesh ring 22r is disposed before and after the hole 22b of the inner tube 22q, and a part of the heat insulating space is used as a water reservoir chamber 22e. Although it is difficult for the wire mesh ring 22r to completely separate the water reservoir chamber 22e from the heat insulating space between the outer tube 22p and the inner tube 22q, other wire mesh ring 22r is used to prevent the exhaust gas from diffusing into the heat insulating space as much as possible. It is good to form it more densely than the part of the wire mesh ring.

  Also according to this embodiment, the water reservoir chamber 22e is formed in the space between the outer tube 22p and the inner tube 22q, so that the condensed water generated from the exhaust gas can be stored in the water reservoir chamber 22e. Since the water reservoir 22e is separated from the flow of the exhaust gas, even if a large amount of exhaust gas flows due to the driver stepping on the accelerator immediately after the engine is started, the condensed water does not scatter. Therefore, it is possible to prevent the condensed water from getting into the exhaust sensor and destroying the sensor.

  The present invention is not limited to the embodiment described above, and various modifications and changes can be made within the scope of the technical idea, and it is obvious that these are equivalent to the present invention.

  For example, in the above description, for the sake of explanation, the case where the water reservoir chamber 22e is provided in the branch pipe 22 has been described, but it is needless to say that the branch pipe 23 may be provided in a large degree of bending.

  In addition to the manifold catalyst, for example, an underfloor catalyst may be disposed in the exhaust passage. In such a case, a bent portion may be provided in the exhaust passage immediately upstream of the exhaust sensor of the underfloor catalyst, and a water reservoir chamber may be formed there.

It is a side view showing the left bank of the V type 6 cylinder engine to which the exhaust passage structure of the internal combustion engine by the present invention is applied. It is a figure which shows the bending part vicinity of # 4 cylinder branch pipe. It is a figure which shows 2nd Embodiment of the exhaust passage structure of the internal combustion engine by this invention. It is a figure which shows 3rd Embodiment of the exhaust passage structure of the internal combustion engine by this invention. It is a figure explaining the effect of 3rd Embodiment. It is a figure which shows 4th Embodiment of the exhaust passage structure of the internal combustion engine by this invention. It is a figure which shows 5th Embodiment of the exhaust passage structure of the internal combustion engine by this invention.

Explanation of symbols

10 Engine (Internal combustion engine)
20 Exhaust manifold (exhaust passage)
21 # 2 cylinder branch pipe (exhaust passage)
22 # 4 cylinder branch pipe (exhaust passage)
23 # 6 cylinder branch pipe (exhaust passage)
22a bent portion 22b hole 22c patch plate 22d retention portion 22e water reservoir 22g outer cylinder 22j hole 22k pipe 22p outer tube 22q inner tube

Claims (3)

An exhaust passage structure for an internal combustion engine,
An exhaust passage upstream of the exhaust sensor that detects the exhaust component is bent and formed, and a staying portion in which condensed water generated from the exhaust gas stays,
A hole formed in the staying part and through which the accumulated condensed water flows;
An outer cylinder provided on the outer periphery of the exhaust passage;
A water reservoir chamber that is formed by an outer peripheral wall of the exhaust passage and the outer cylinder, and stores condensed water that has flowed down from the hole;
A second hole formed on the inner peripheral side of the bent portion of the exhaust passage;
I have a,
The water vapor rising in the outer cylinder flows into the exhaust passage through the second hole,
An exhaust passage structure for an internal combustion engine. An exhaust passage structure for an internal combustion engine,
An exhaust passage upstream of the exhaust sensor that detects the exhaust component is bent and formed, and a staying portion in which condensed water generated from the exhaust gas stays,
A hole formed in the staying part and through which the accumulated condensed water flows;
A second hole formed on the inner peripheral side of the bent portion of the exhaust passage;
A pipe communicating the second hole and the hole formed in the stay part;
An exhaust passage structure for an internal combustion engine, comprising: The exhaust passage is a branch pipe of an exhaust manifold,
The exhaust passage structure for an internal combustion engine according to claim 1 or 2 , characterized in that

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