JP2016128651A - Exhaust pipe structure of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust pipe structure of an internal combustion engine, which can uniformly supply exhaust gas to a catalyst carrier without causing an excessive pressure loss.SOLUTION: An upstream side exhaust pipe 2, which is connected in communication to an exhaust gas introduction side of a catalytic converter 1 with a catalyst carrier 10 built in, comprises a straight pipe part 20 joined to the exhaust gas introduction side of the catalytic converter, a first bent pipe part 21 that is connected in communication to the straight pipe part and is formed to bend in a first direction, and a second bent pipe part 22 that is connected in communication to the first bent pipe part and is formed to bend in a second direction different from the first direction. Further, a communication hole may be perforated in at least one of the first and second bent pipe parts, and a covering pipe may be joined to surround the communication hole.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an exhaust pipe structure of an internal combustion engine, and more particularly to an exhaust pipe structure of an internal combustion engine that includes a catalytic converter and is suitable for an internal combustion engine of an automobile.

  In an automobile exhaust system equipped with a catalytic converter that purifies exhaust gas from an internal combustion engine, it is desirable that the exhaust gas be supplied uniformly to the catalyst carrier in the catalytic converter. On the other hand, in view of the arrangement of the catalytic converter and the like, it is common that a bent portion is formed in the upstream exhaust pipe connected to the exhaust gas introduction side of the catalytic converter. In particular, if a bent portion is formed immediately before the catalytic converter, the exhaust gas flow introduced into the catalytic converter and supplied to the catalytic carrier is deflected, and the effective area of the catalytic carrier cannot be fully utilized. In view of this point, for example, the following Patent Document 1 states that “exhaust gas uniformly hits the entire upstream end face of the exhaust gas purifying body, allows the exhaust gas to flow uniformly into the exhaust gas purifying body without unevenness, and The object is to provide an exhaust gas purification device having a uniform gas flow velocity distribution and excellent purification efficiency, and includes an “exhaust gas inflow pipe, an exhaust gas purification body, and a cone connecting them. In the mixed flow type exhaust gas purification apparatus in which the axis of the exhaust gas inflow pipe is inclined with respect to the upstream end face of the exhaust gas purifying body, the actual angle is 45 ° or less with respect to the upstream end face of the exhaust gas purifying body. And the axis offset by a predetermined amount to the inclined side is used as the axis of the exhaust gas inflow pipe, and at least outward from the side of the cone opposite to the side where the exhaust gas inflow pipe is inclined. Curving Thereby forming a curved bulge portion to output "device has been proposed (described in paragraph Patent Document 1 [0014] and [0015]).

  Patent Document 2 states that “a vehicle exhaust line in which an exhaust gas purification catalytic converter is disposed in an exhaust line in an internal combustion engine and a bent portion of the exhaust line is formed immediately before the catalytic converter. A structure is proposed in which a gas flow redirecting portion is provided at the outer corner portion of the bent portion for bringing the exhaust gas flow upstream of the catalytic converter toward the inner corner portion side of the bent portion (patent) In Patent Document 3, paragraph [0005], Patent Document 3 states that "the upstream exhaust pipe structure of the catalytic converter having a bent portion in the upstream exhaust pipe of the catalytic converter, and the bent in the upstream exhaust pipe. A structure in which a rectification unit is formed near the inlet of the catalytic converter on the downstream side of the unit ”(described in paragraph [0007] of Patent Document 3) is proposed.

  Further, in Patent Document 4 below, “an exhaust pipe through which exhaust gas exhausted from an internal combustion engine passes, a housing that is provided downstream of the exhaust pipe and contains an exhaust gas purification catalyst that purifies the exhaust gas, and A part of the housing is formed, the flow of the exhaust gas is bent and introduced into the exhaust gas purification catalyst, and the bent inner side connected from the exhaust pipe to the housing, and continuously from the exhaust pipe toward the housing And an introduction part having a bent outer side that reduces the flow rate of the exhaust gas by expanding and connecting, and forming a high-pressure part where the pressure generated by the flow of the exhaust gas is increased outside the bent part of the introduction part On the other hand, a low pressure part in which the pressure generated by the flow of the exhaust gas is lower than that of the high pressure part is formed inside the bent part of the introduction part. It is (described in paragraph of Patent Document 4 [0011]). Further, in Patent Document 5, “in an exhaust purification apparatus that employs a layout in which an exhaust system is provided with an aftertreatment device that passes exhaust gas to be purified, and the exhaust gas is inverted and introduced into the aftertreatment device, An inlet portion for enclosing the inlet side end face of the post-processing device and introducing exhaust gas through the exhaust inlet from a direction substantially orthogonal to the axial direction of the post-processing device; An exhaust gas purifying apparatus is proposed in which a first hollow portion is formed in the introduction portion that is warped away from the exhaust introduction port and is closer to the inlet side end surface of the aftertreatment device as the exhaust gas is introduced from the exhaust introduction port. (Described in paragraph [0015] of Patent Document 5).

  Patent Document 6 discloses that an exhaust pipe provided with an exhaust gas sensor that is disposed upstream of an exhaust purification catalyst that purifies exhaust gas discharged from an engine body of an internal combustion engine and that detects the state of the exhaust gas. A throttle portion having a smaller flow path cross-sectional area than the upstream side and the downstream side is provided, and the exhaust gas sensor includes a minimum cross-sectional area portion having a minimum flow path cross-sectional area of the throttle portion, and a side of the exhaust purification catalyst. An exhaust pipe provided between the downstream end and the downstream end is proposed (described in paragraph [0009] of Patent Document 6).

JP 2004-332607 A JP 2006-17018 A JP 2007-263003 A JP 2007-303398 A JP 2009-68415 A JP 2011-17261 A

  In Patent Documents 1 to 6, in order to forcibly deflect the exhaust gas flow introduced into the catalytic converter, the bent portion shape of the exhaust pipe immediately before the catalytic converter is changed (Patent Documents 1 and 4), or A gas flow turning section (Patent Document 2), a rectifying section (Patent Document 3), a hollow section (Patent Document 5), a throttle section (Patent Document 6), and the like are formed in the upstream exhaust pipe. For this reason, as a result, the flow path area is reduced in any case, and generation of pressure loss is unavoidable. In addition, it is not easy to form a three-dimensional shape portion on the exhaust pipe or the like, which causes an increase in cost. In addition, although patent document 6 is proposed about arrangement | positioning of an exhaust gas sensor, the relationship with said throttle part is a premise.

  Therefore, the present invention provides an exhaust pipe for an internal combustion engine that can supply exhaust gas evenly to the catalyst carrier without causing excessive pressure loss, even if the exhaust pipe has a curved pipe portion on the upstream side of the catalytic converter. It is an object to provide a structure.

  To achieve the above object, the present invention includes a catalytic converter that incorporates a catalyst carrier and purifies exhaust gas of an internal combustion engine, and an upstream exhaust pipe that is connected to the exhaust gas introduction side of the catalytic converter. In the exhaust pipe structure of the internal combustion engine, the upstream side exhaust pipe is connected to the exhaust gas introduction side of the catalytic converter and a straight pipe portion is connected to the straight pipe portion and bent in the first direction. 1 bent pipe portion and a second bent pipe portion connected in communication with the first bent pipe portion and bent in a second direction different from the first direction. is there.

 As a 1st and 2nd direction in the said 1st and 2nd curved pipe part, the aspect set to a different direction by the up-down direction of a vehicle, the aspect set to a different direction by the left-right direction of a vehicle, Furthermore, both are There is a mode in which they are combined and set in the vertical and horizontal directions of the vehicle.

  In the above exhaust pipe structure, the straight pipe portion may have a substantially same axis as a central axis of the catalyst carrier. The straight pipe portion and the first bent pipe portion may have a substantially same flow path area. Furthermore, it is good also as providing the connection straight pipe part interposed between the said 1st curved pipe part and the said 2nd curved pipe part.

  Further, in the exhaust pipe structure, the catalytic converter includes an exhaust gas introduction part joined to the straight pipe part, and the exhaust gas introduction part expands from the straight pipe part toward the catalyst carrier. A configuration having a bell mouth shape formed as described above is preferable.

  Furthermore, in the above exhaust pipe structure, the upstream exhaust pipe has a communication hole formed in at least one of the first curved pipe part and the second curved pipe part. It is good to have the cladding tube joined so that it may surround.

  Since this invention is comprised as mentioned above, there exist the following effects. That is, in the exhaust pipe structure of the internal combustion engine of the present invention, the upstream exhaust pipe connected to the exhaust gas introduction side of the catalytic converter has a straight pipe portion joined to the exhaust gas introduction side of the catalytic converter, and the straight pipe portion. A first curved pipe portion connected in communication with the pipe portion and bent in the first direction, and connected in communication with the first bent pipe portion and bent in a second direction different from the first direction. In addition, since the second bent pipe portion is provided, the exhaust gas can be evenly supplied to the catalyst carrier without causing excessive pressure loss. For example, in comparison with a conventional exhaust pipe having a curved pipe portion on the upstream side of the catalytic converter, the present invention includes the first curved pipe portion in addition to the second curved pipe portion corresponding to the curved pipe portion. The exhaust gas that has drifted in the second curved pipe portion flows along the inside of the first curved pipe portion and is rectified in the straight pipe portion on the downstream side of the exhaust gas. The exhaust gas can be supplied uniformly.

  In the exhaust pipe structure described above, if the straight pipe portion has a configuration that has substantially the same axis as the central axis of the catalyst carrier, it can be easily rectified when exhaust gas is uniformly supplied to the catalyst carrier. it can. If the straight pipe portion and the first bent pipe portion have substantially the same flow path area, the flow path resistance can be minimized. Furthermore, if the connecting straight pipe part interposed between the first bent pipe part and the second bent pipe part is provided, the first and second bent pipe parts are easily and continuously formed. be able to.

  Further, in the above exhaust pipe structure, if the exhaust gas introduction part of the catalytic converter has a bell mouth shape formed so as to expand from the straight pipe part toward the catalyst carrier, it is introduced into the catalytic converter. Since the exhaust gas is smoothly guided by the bell mouth shaped exhaust gas introduction section, the uniformity of the exhaust gas supplied to the catalyst carrier can be further improved.

  Further, in the above exhaust pipe structure, if the upstream exhaust pipe has a communication hole formed in at least one of the first curved pipe portion and the second curved pipe portion, the exhaust gas is condensed. Even if water stays in the exhaust pipe, it can be appropriately discharged. Further, if a cladding tube joined so as to surround the communication hole is provided, it is possible to reliably prevent the exhaust gas from being discharged together with the condensed water from the communication hole.

It is a side view which shows the exhaust pipe structure which concerns on one Embodiment of this invention. It is sectional drawing which expands and shows a part of exhaust pipe structure which concerns on one Embodiment of this invention. It is sectional drawing which shows the exhaust gas flow of the simulation result in one Embodiment of this invention. It is a side view which shows the exhaust pipe structure which concerns on other embodiment of this invention. It is a figure which shows the plane (A) and side surface (B) of the other aspect of the exhaust pipe structure which concerns on one Embodiment of this invention. It is a figure which shows the plane (A) and side surface (B) of the other aspect of the exhaust pipe structure which concerns on one Embodiment of this invention. It is a figure which shows the plane (A) and side surface (B) of another aspect of the exhaust pipe structure which concerns on one Embodiment of this invention. It is a figure which shows the plane (A) and side surface (B) of the exhaust pipe structure which concern on other embodiment of this invention. It is sectional drawing which expands and shows a part of exhaust pipe structure which concerns on other embodiment of this invention. It is a side view which shows the exhaust pipe structure which concerns on another embodiment of this invention. It is sectional drawing which expands and shows a part of exhaust pipe structure which concerns on another embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. 1 and 2 show an exhaust pipe structure of an internal combustion engine according to an embodiment of the present invention. A catalytic converter 1 that contains a catalyst carrier 10 and purifies exhaust gas from an internal combustion engine (not shown), and its And an upstream exhaust pipe 2 joined to the exhaust gas introduction side. A downstream exhaust pipe 3 is joined to the exhaust gas discharge side of the catalytic converter 1, and the downstream exhaust pipe 3 is connected in communication with a silencer (not shown). Further, in the present embodiment, the oxygen sensor 4 is attached to the straight pipe portion 20. The catalytic converter 1 has a metal cylinder body 11 containing a catalyst carrier 10, and an exhaust gas introduction part 12 and an exhaust gas discharge part 13 formed integrally with the body part 11, for example. A buffer member (mat) 14 is disposed so as to wind 10, and the catalyst carrier 10 is stably held in the main body 11.

  In general, the catalytic converter 1 is disposed under the floor of a vehicle (not shown), and is connected to an exhaust manifold (not shown) of an internal combustion engine disposed thereabove via an upstream exhaust pipe 2. . Accordingly, at least one bent portion is required for the upstream side exhaust pipe 2, but if the catalytic converter 1 is joined immediately after the bent portion, various problems such as an increase in the flow path resistance described above are caused. For this reason, the upstream side exhaust pipe 2 of the present embodiment is configured as follows.

  That is, the upstream side exhaust pipe 2 of the present embodiment has a straight pipe portion 20, a connecting straight pipe portion 24, a first bent portion in order from the catalytic converter 1 side, as shown in FIG. 1 and FIG. It has a pipe part 21, a second bent pipe part 22 and a straight pipe part 23. The straight pipe portion 20 is joined to the exhaust gas introduction side of the catalytic converter 1, the first bent pipe portion 21 is bent in the first direction and connected to the straight pipe portion 20, and the second bent pipe portion 22 is It is bent in a second direction different from the first direction, is connected to the first curved pipe portion 21 via the connecting straight pipe portion 24, and is joined to the straight pipe portion 23.

  As the first and second directions in the first and second curved pipe portions 21 and 22, as shown in FIG. 1, different modes are set in the vertical direction (on the vertical plane) of the vehicle, as shown in FIG. A mode in which the vehicle is set in different directions in the left-right direction (horizontal plane) as shown, and a mode in which both are combined and set in the vertical and horizontal directions (three-dimensional space) of the vehicle as shown in FIG. Yes, will be described in turn. In each figure, a portion where the pipe member is bent (for example, the boundary between the second bent pipe portion 22 and the straight pipe portion 23) is indicated by a one-dot chain line. In FIGS. 4 is omitted.

  In the embodiment shown in FIGS. 1 and 2, the straight pipe portion 20 has an axis substantially the same as the central axis of the catalyst carrier 10 so that exhaust gas is evenly supplied to the catalyst carrier 10. It is configured. Moreover, the straight pipe part 20 and the 1st curved pipe part 21 have the substantially same flow path area, and can suppress flow path resistance to the minimum. FIG. 3 shows an exhaust gas flow when a simulation is performed on the embodiment shown in FIGS. 1 and 2, and a thin line in FIG. 3 represents a streamline.

  According to the above simulation results, the main flow (indicated by a broken line in FIG. 3) of the exhaust gas that has drifted outward (upward in FIG. 3) along the second curved pipe portion 22 is along the inside of the first curved pipe portion 21. It is confirmed that the exhaust gas is uniformly supplied to the entire front surface of the catalyst carrier 10 by being rectified by the straight pipe portion 20 on the downstream side and centered. In addition, the flow velocity of exhaust gas is the maximum in the area | region shown with a broken line in FIG. In the upstream side exhaust pipe 2 of the present embodiment, “uniform” representing the uniformity of the exhaust gas supplied to the catalyst carrier 10 as compared with the conventional exhaust pipe having the curved pipe portion on the upstream side of the catalytic converter. It was confirmed that the “degree” improved by 4.7%.

  As described above, the straight pipe portion 20 and the first curved pipe portion 21 in the upstream side exhaust pipe 2 of the present embodiment are set to substantially the same flow path area, but are set to different flow path areas. May be. For convenience of manufacturing, a connecting straight pipe portion 24 is interposed between the first bent pipe portion 21 and the second bent pipe portion 22. It is good also as forming the 2 curved pipe parts 22 in the continuous curved pipe.

  FIG. 4 shows a catalytic converter 1x according to another embodiment, in which an exhaust gas introduction part 12x joined to the straight pipe part 20 is formed in a cone shape having an axis inclined with respect to the axis of the catalyst carrier 10, The axis of the exhaust gas introduction part 12x is configured to coincide with the axis of the straight pipe part 20. As a result, since the axis of the straight pipe portion 20 is not orthogonal to the front surface of the catalyst carrier 10, the shape of the exhaust gas introduction portion 12x is changed in consideration of the uniformity of the exhaust gas supplied to the catalyst carrier 10. It is necessary to take measures, but it is omitted here.

  FIG. 5 shows a mode in which the first and second directions in the first and second curved pipe portions 21 and 22 are set in different directions in the left and right direction (horizontal plane) of the vehicle. As shown to (A) and the side view to (B), the 1st curved pipe part 21 is bent and formed on the horizontal surface instead of the vertical surface. As described above, in the aspect shown in FIG. 5, the second direction of the second curved pipe portion 22 is set to the vertical direction (on the vertical plane) of the vehicle, whereas the first curved pipe portion 21 The first direction is set in the left-right direction (on the horizontal plane) of the vehicle, and three-dimensional centering is performed, but the other configuration is the same as that shown in FIG.

  FIG. 6 shows a mode in which the first and second directions in the first and second curved pipe portions 21 and 22 are set in the vertical and horizontal directions (three-dimensional space) of the vehicle. The two bent pipe portions 21 and 22 are bent in a non-coplanar plane, and three-dimensional centering is also performed in this mode. The side view of this mode is the same as that of FIG. 1 as shown in FIG. 1B, but the plan view of FIG. 6 is the plan view of the mode shown in FIG. 1 as shown in FIG. However, this is different from a plan view similar to FIG.

  FIG. 7 shows a mode in which a third curved pipe portion 25 is further provided in addition to the first and second curved pipe portions 21 and 22, and a plan view thereof is shown in FIG. This is shown in (B). That is, the upstream side exhaust pipe 2 described in each of the above figures is an aspect having two curved pipe portions of the first and second curved pipe portions 21 and 22, but as shown in FIG. Alternatively, the bent pipe portion 25 may be formed. According to this aspect, it is possible to further improve the uniformity supplied to the catalyst carrier 10 by reducing the flow rate of the exhaust gas in the third curved pipe portion 25, but the pressure loss increases.

  FIG. 8 shows a catalytic converter 1y according to still another embodiment of the present invention, and a plan view thereof is shown in (A) and a side view thereof is shown in (B). In the present embodiment, as shown in an enlarged view in FIG. 9, the exhaust gas introduction part 12 y joined to the straight pipe part 20 is formed so as to increase in diameter from the straight pipe part 20 toward the catalyst carrier 10. Has a bell mouth shape. That is, it has the shape of a tube end formed in a bell shape in order to reduce channel resistance. Thus, since the exhaust gas introduced into the catalytic converter 1y is smoothly guided by the bell mouth-shaped exhaust gas introduction part 12y, the uniformity of the exhaust gas supplied to the catalyst carrier 10 is further improved. become. In addition, if said exhaust-gas introduction part 12y is joined to the upstream exhaust pipe 2 of each above-mentioned aspect, there can exist a synergistic effect regarding the improvement of uniformity.

  10 and 11 show another embodiment of the present invention. FIG. 10 shows the entire side surface, and FIG. 11 shows a partially enlarged cross section. In the embodiment shown in FIG. 1 and FIG. 2 described above, depending on the state of the upstream exhaust pipe 2 mounted on the vehicle, the condensed water of the exhaust gas is present in the first curved pipe section 21 or the second curved pipe section 22. There is a possibility of stagnation. Since such condensed water is normally discharged together with the exhaust gas due to the pressure of the exhaust gas at the start of the internal combustion engine (not shown), it does not cause a problem. In the aspect in which the oxygen sensor 4 is provided, it is desirable to take some measures in order to avoid water scattered when discharged together with the exhaust gas from adhering to the oxygen sensor 4.

  For this reason, in the present embodiment, as shown in an enlarged view in FIG. 11, one of the first and second curved pipe portions 21 and 22, in particular, the curved pipe portion located in the lowermost position (in the figure, the first 2 is provided with a communication hole 6 for draining water. Further, a cladding pipe 5 that covers the communication hole 6 is joined to the upstream exhaust pipe 2 in order to prevent exhaust gas from being discharged together with condensed water from the communication hole 6. The cladding tube 5 of the present embodiment includes both the first and second curved pipe portions 21 and 22, and is configured to cover the straight pipe portion 20 and the exhaust gas introduction portion 12, and is an upper member having a substantially semicircular cross section. 51 and the lower member 52 are joined to each other and joined to the catalytic converter 1 and the upstream exhaust pipe 2. Furthermore, if the Helmholtz resonance chamber is configured by using the communication hole 6 as a neck tube and the cladding tube 5 as a resonance chamber, it is possible to contribute to noise reduction.

  Thus, even if any of the above embodiments and aspects is applied to any part of the exhaust system (not shown) of the internal combustion engine, it is possible to ensure the uniformity of the exhaust gas supplied to the catalyst carrier 10. it can. For example, when the catalytic converter 1 is mounted on an exhaust manifold (not shown) portion of an internal combustion engine, the catalytic converter 1 may be applied to an exhaust pipe (that is, a branch pipe) on the upstream side thereof. Or a combination thereof.

1, 1x, 1y Catalytic converter 2 Upstream exhaust pipe 3 Downstream exhaust pipe 4 Oxygen sensor 5 Covering pipe 6 Communication hole 10 Catalyst carrier 11 Main body part 12, 12x, 12y Exhaust gas introduction part 20 Straight pipe part 21 First curve Pipe part 22 Second bent pipe part 23 Straight pipe part 24 Connected straight pipe part 25 Third bent pipe part

Claims (6)

  In the exhaust pipe structure of an internal combustion engine comprising a catalytic converter that contains a catalyst carrier and purifies exhaust gas of the internal combustion engine, and an upstream exhaust pipe that is connected to the exhaust gas introduction side of the catalytic converter, the upstream exhaust A straight pipe part joined to the exhaust gas introduction side of the catalytic converter; a first curved pipe part connected to the straight pipe part and bent in a first direction; and An exhaust pipe structure for an internal combustion engine, comprising: a second curved pipe portion that is connected to the pipe portion and is bent in a second direction different from the first direction.   The exhaust pipe structure for an internal combustion engine according to claim 1, wherein the straight pipe portion has an axis substantially the same as a central axis of the catalyst carrier.   The exhaust pipe structure for an internal combustion engine according to claim 1 or 2, wherein the straight pipe portion and the first curved pipe portion have substantially the same flow path area.   4. The internal combustion engine according to claim 1, further comprising a connecting straight pipe portion interposed between the first bent pipe portion and the second bent pipe portion. 5. Exhaust pipe structure.   The catalytic converter includes an exhaust gas introduction part joined to the straight pipe part, and the exhaust gas introduction part has a bell mouth shape formed so as to expand in diameter from the straight pipe part toward the catalyst carrier. The exhaust pipe structure for an internal combustion engine according to any one of claims 1 to 4, wherein the exhaust pipe structure is provided.   The upstream exhaust pipe has a communication hole formed in at least one of the first curved pipe part and the second curved pipe part, and a cladding pipe joined so as to surround the communication hole. The exhaust pipe structure for an internal combustion engine according to any one of claims 1 to 5, wherein the exhaust pipe structure is provided.

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