JP2006307667A - Exhaust pipe structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve silencing effect materializing reduction in exhaust sound through expansion effect in proportion to an expansion ratio by increasing the expansion ratio. <P>SOLUTION: From the longitudinal center part 32A of the front 32 toward the longitudinal center part 34A of the center part 34 in an elliptical sectional flat part 30 provided to an exhaust pipe 24 in an exhaust system 10, the cross sectional width in a vehicle body vertical direction is extended from the minor axis to the major axis of the ellipse. Through the expansion effect in proportion to the expansion ratio, exhaust sound can be reduced. From the longitudinal center part 34A of the center part 34 toward the longitudinal center part 36A of the back 36 in the flat part 30, in addition, the cross sectional width in the vehicle body width direction is extended from the minor axis to the major axis of the ellipse. Through the expansion effect in proportion to the expansion ratio, exhaust sound can be reduced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exhaust pipe structure of a vehicle such as an automobile.

2. Description of the Related Art Conventionally, in an exhaust pipe structure of a vehicle such as an automobile, an exhaust pipe disposed from a silencer through a gap between a cab and a loading platform is disposed substantially perpendicular to the first circular portion and the gap. Has been proposed that includes an elliptical portion that is flat in the longitudinal direction of the vehicle and that corresponds to the gap (see, for example, Patent Document 1).
Japanese Utility Model Open 05-92418

  However, in the exhaust pipe structure as in Patent Document 1, a first circular portion having a circular cross section and an elliptical portion whose cross section is flat in the front-rear direction of the vehicle body are connected to each other by a conversion portion. As a result, since the ratio between the diameter of the first circular portion and the long axis of the elliptical shape becomes the expansion ratio, the expansion ratio cannot be increased. Further, since the exhaust noise is reduced in proportion to the expansion ratio, a sufficient silencing effect cannot be obtained.

  In view of the above facts, an object of the present invention is to provide an exhaust pipe structure capable of increasing the expansion ratio and improving the silencing effect.

  The exhaust pipe structure according to the first aspect of the present invention has a first flat portion whose cross-sectional shape is a flat cross section having a predetermined direction as a major axis and a direction perpendicular to the major axis as a minor axis, and the first It has the 2nd flat part which was connected to the flat part and at least one of the long axis and the short axis was expanded with respect to the said 1st flat part.

  Since at least one of the long axis and the short axis of the second flat part of the flat cross section is extended with respect to the first flat part of the flat cross section, the exhaust gas is proportional to the expansion ratio of the flat cross section to the flat cross section. Sound is effectively reduced.

  According to a second aspect of the present invention, in the exhaust pipe structure according to the first aspect, the second flat portion is connected in series to the first flat portion, and has a direction orthogonal to the major axis of the first flat portion. A long axis is provided, and the cross-sectional area is the same as that of the first flat portion.

  Since the second flat portion includes a portion whose major axis is a direction orthogonal to the long axis of the first flat portion, the short axis direction of the first flat portion becomes the long axis direction of the second flat portion, and the first flat portion The ratio of the minor axis of the part and the major axis of the second flat part is the expansion ratio. As a result, the expansion ratio becomes larger than the expansion ratio from the circular cross section to the flat cross section, and the exhaust noise is reduced in proportion to the increased expansion ratio. Further, since the first flat portion and the second flat portion have the same in-pipe cross-sectional area, the exhaust pressure loss hardly deteriorates.

  According to a third aspect of the present invention, in the exhaust pipe structure according to the first aspect, the first flat portion is inserted into the second flat portion, and the first flat portion and the second flat portion have the same major axis. It has a similar cross-sectional shape as a direction.

  Since the second flat part and the first flat part inserted into the second flat part have similar cross-sectional shapes in which the major axis directions are the same, they are diffused from the first flat part into the second flat part. The entire expansion direction of the first flat portion has the same expansion ratio with respect to the exhaust gas. As a result, an efficient expansion effect can be obtained as compared with expansion from a circular cross section to a flat cross section, and exhaust noise is reduced.

  According to the exhaust pipe structure of the present invention, the expansion ratio can be increased and the silencing effect can be improved.

  According to a second aspect of the present invention, in the exhaust pipe structure according to the first aspect, the second flat portion is connected in series to the first flat portion, and a direction perpendicular to the long axis of the first flat portion is defined as a long axis. The exhaust pressure loss hardly deteriorates because it has the same cross-sectional area as the first flat portion.

  According to a third aspect of the present invention, in the exhaust pipe structure according to the first aspect, the first flat portion is inserted into the second flat portion, and the second flat portion and the first flat portion have the major axis and the minor axis in the same direction. Because of the similar cross-sectional shape, the silencing effect is great and the overall length of the exhaust system can be shortened.

  A first embodiment of an exhaust pipe structure according to the present invention will be described with reference to FIGS.

  In the figure, the arrow UP indicates the vehicle body upward direction, and the arrow FR in the figure indicates the vehicle body front direction.

  As shown in FIG. 2, the exhaust system 10 of the vehicle body of the present embodiment is attached to the lower surface of the vehicle body from the front of the vehicle body toward the rear of the vehicle body, and the exhaust system 10 flows in the direction in which the exhaust gas discharged from the engine flows. The catalytic converter 12, the main muffler 14, and the tail pipe 16 are arranged in this order. The catalytic converter 12 is connected to an exhaust manifold (not shown) by an exhaust pipe 20.

  The catalytic converter 12 and the main muffler 14 are connected by an exhaust pipe 22, and a flange 22 </ b> A as a joint is provided at a longitudinal intermediate portion of the exhaust pipe 22. Further, the main muffler 14 and the tail pipe 16 are connected by an exhaust pipe 24, and a flange 24 </ b> A as a joint is provided at an intermediate portion in the longitudinal direction of the exhaust pipe 24.

  As shown in FIG. 3, the cross-sectional shape of the exhaust pipe 24 is a circle having an inner diameter A1, and the cross-sectional area in the pipe is S0. The cross-sectional shape of the tail pipe 16 is the same as the cross-sectional shape of the exhaust pipe 24, and the cross-sectional area in the pipe is S0.

  As shown in FIG. 1, a flat portion 30 is formed at a portion between the circular cross section 24 </ b> B of the exhaust pipe 24 and the tail pipe 16 instead of a conventionally provided sub-muffler. Further, in the flat portion 30, the exhaust pipe 24 is continuously crushed into an elliptical cross section in the vehicle body vertical direction (vertical direction) and the vehicle width direction (lateral direction), from the main muffler 14 side to the tail pipe 16 side. The longitudinal cross-sectional area is the same, and the major axis direction of the elliptical shape is the front part 32, the central part 34, and the rear part 36 that are changed around the axis of the exhaust pipe 24.

  In other words, the flat portion 30 of the exhaust pipe 24 is composed of three parts, namely, a front part 32, a central part 34, and a rear part 36, whose elliptical cross-sectional shape is rotated 90 degrees around the axis of the exhaust pipe 24.

  When the front part 32 of the flat part 30 is the first flat part, the central part 34 corresponds to the second flat part, and when the central part 34 is the first flat part, the rear part 36 corresponds to the second flat part. Further, the overall height and width of the flat portion 30 are smaller than the overall height and width of the main muffler 14, respectively.

  As shown in FIG. 4, the cross-sectional shape of the central portion 32A in the longitudinal direction of the front portion 32 of the flat portion 30 of the exhaust pipe 24 is an ellipse having a major axis B1 and a minor axis B2, and the major axis B1 is in the vehicle width direction. It has become. The cross-sectional shape of the central portion 36A in the longitudinal direction of the rear portion 36 in the flat portion 30 is also the same elliptical shape as the cross-sectional shape of the central portion 32A in the longitudinal direction of the front portion 32.

  As shown in FIG. 5, the cross-sectional shape of the central portion 34A in the longitudinal direction of the central portion 34 of the flat portion 30 is an ellipse having a short axis C1 and a long axis C2, and the long axis C2 is the vertical direction of the vehicle body. . Therefore, the cross-sectional shape of the central part 34A in the longitudinal direction of the central part 34 in the flat part 30 is such that the short axis and the long axis are different from the longitudinal central part 32A of the front part 32 and the longitudinal central part 36A of the rear part 36, respectively. It has an elliptical cross-sectional shape rotated 90 degrees around the axis of the exhaust pipe 24.

  As shown in FIG. 2, when the flat portion 30 of the exhaust pipe 24 is viewed from the side of the vehicle body, from the circular cross-sectional portion 24B of the exhaust pipe 24 to the longitudinal center portion 32A of the front portion 32 of the flat portion 30, The vertical width H of the exhaust pipe 24 is gradually narrowed, and the vertical width H of the exhaust pipe 24 gradually increases from the longitudinal central portion 32A of the front portion 32 of the flat portion 30 to the longitudinal central portion 34A of the central portion 34. It is getting wider. Further, the vertical width H of the exhaust pipe 24 is gradually narrowed from the longitudinal central portion 34A of the central portion 34 of the flat portion 30 to the longitudinal central portion 36A of the rear portion 36, and the longitudinal direction of the rear portion 36 of the flat portion 30 is reduced. The vertical width H of the exhaust pipe 24 gradually increases from the central portion 36A to the tail pipe 16.

  As shown in FIGS. 3 and 4, the cross-sectional width extends in the vehicle width direction (lateral direction) from the circular cross-sectional portion 24 </ b> B of the exhaust pipe 24 to the longitudinal center portion 32 </ b> A of the front portion 32 of the flat portion 30. (Expansion ratio B1 / A1). Therefore, exhaust noise generated by exhaust pulsation can be reduced by the expansion effect proportional to the expansion ratio B1 / A1 in the lateral direction of the exhaust pipe 24.

  Further, as shown in FIGS. 4 and 5, the cross-sectional width is expanded in the vehicle body vertical direction (vertical direction) from the longitudinal center portion 32 </ b> A of the front portion 32 of the flat portion 30 to the longitudinal center portion 34 </ b> A of the center portion 34. (Expansion ratio C2 / B2). Therefore, the exhaust effect generated by exhaust pulsation can be reduced by the expansion effect proportional to the longitudinal expansion ratio C2 / B2 of the exhaust pipe 24.

  Further, the cross-sectional width is expanded in the vehicle width direction (lateral direction) from the longitudinal central portion 34A of the central portion 34 of the flat portion 30 to the longitudinal central portion 36A of the rear portion 36 (expansion ratio B1 / C1). Therefore, the exhaust effect generated by the exhaust pulsation can be reduced by the expansion effect proportional to the lateral expansion ratio B1 / C1 of the exhaust pipe 24.

  Further, from the longitudinal center portion 36A of the rear portion 36 of the flat portion 30 to the tail pipe 16, the cross-sectional width is expanded in the vehicle body vertical direction (vertical direction) (expansion ratio A1 / B2). Therefore, the exhaust effect generated by exhaust pulsation can be reduced by the expansion effect proportional to the vertical expansion ratio A1 / B2 of the exhaust pipe 24.

  In addition, since the expansion of the flat portion 30 of the exhaust pipe 24 is one of the vertical direction and the horizontal direction, the expansion effect (noise reduction effect) is greater than the structure of the exhaust pipe 24 having an expansion effect in the entire circumferential direction. Will be less.

  Next, the operation of this embodiment will be described.

  In the present embodiment, in the flat portion 30 provided in the exhaust pipe 24 of the exhaust system 10, as shown in FIGS. 3 and 4, the center in the longitudinal direction of the front portion 32 of the flat portion 30 from the circular cross-section portion 24 B of the exhaust pipe 24. Over the portion 32A, the cross-sectional width is expanded in the vehicle width direction (lateral direction) (expansion ratio B1 / A1). As a result, exhaust noise generated by exhaust pulsation can be reduced by an expansion effect proportional to the expansion ratio B1 / A1.

  4 and 5, the cross-sectional width is elliptical in the vehicle body vertical direction (vertical direction) from the longitudinal central portion 32A of the front portion 32 of the flat portion 30 to the longitudinal central portion 34A of the central portion 34. The shape is extended from the short axis to the long axis (expansion ratio C2 / B2). As a result, due to the expansion effect proportional to the expansion ratio C2 / B2, exhaust noise generated by exhaust pulsation can be reduced compared to expansion from a circular cross section to a flat cross section.

  In addition, from the longitudinal central portion 34A of the central portion 34 of the flat portion 30 to the longitudinal central portion 36A of the rear portion 36, the cross-sectional width extends in the vehicle width direction (lateral direction) from an elliptical minor axis to a major axis. Due to the expansion effect proportional to the expansion ratio B1 / C1, the exhaust noise generated by the exhaust pulsation can be reduced compared to the expansion from the circular cross section to the flat cross section.

  Further, from the longitudinal center portion 36A of the rear portion 36 of the flat portion 30 to the tail pipe 16, the cross-sectional width extends in the vehicle body vertical direction (longitudinal direction) (expansion ratio A1 / B2), and the expansion ratio A1 / B2 increases. Due to the proportional expansion effect, exhaust noise generated in the exhaust system 10 due to exhaust pulsation can be reduced.

  Therefore, in this embodiment, the silencing performance of the exhaust system 10 is improved. Moreover, since the noise reduction performance of the exhaust system 10 is improved, the sub-muffler can be eliminated. As a result, cost reduction and weight reduction are possible.

  In the present embodiment, the cross-sectional area of the circular cross section 24B of the exhaust pipe 24, the cross-sectional areas of the front portion 32, the central portion 34, and the rear portion 36 of the flat portion 30, and the cross-sectional area of the tail pipe 16 are as follows. Since they are substantially equal, there is almost no deterioration of exhaust loss.

  In the present embodiment, the noise reduction performance of the exhaust system 10 can be improved by providing the flat portion 30 in the exhaust pipe 24. As a result, the ratio of noise reduction in the main muffler 14 in the exhaust system 10 can be reduced, so that the main muffler 14 can be super flattened. Furthermore, by making the main muffler 14 extremely flat, it is possible to cope with a low floor for expanding the interior space of the vehicle and an increase in ground height for improving running performance (performance on a road with large unevenness). Productivity is improved.

  Next, a second embodiment of the exhaust pipe structure of the present invention will be described with reference to FIGS.

  In addition, the same member as 1st Embodiment attaches | subjects the same code | symbol, and abbreviate | omits the description.

  As shown in FIG. 6, unlike the first embodiment, in this embodiment, the main muffler 14 corresponds to the second flat portion, and the exhaust pipe 40 inserted in the main muffler 14 corresponds to the first flat portion. Yes. Further, the exhaust pipe 40 connects the catalytic converter 12 and the tail pipe 16, and flanges 40 </ b> A and 40 </ b> B as joints are provided at the longitudinal intermediate portion of the exhaust pipe 40.

  The inside of the main muffler 14 is divided into a plurality of expansion chambers 48, 50, 52 having different axial lengths by a plurality of separators 42, 44.

  As shown in FIG. 7, the exhaust pipe 40 is disposed coaxially with the axis P1 of the main muffler 14, and the portion inside the main muffler 14 in the exhaust pipe 40 is a flat portion 40C.

  As shown in FIG. 6, the flat portion 40C of the exhaust pipe 40 that passes through the expansion chambers 48, 50, 52 is formed with a plurality of through holes 56 through which the exhaust passes, and through these through holes 56, Exhaust gas in the exhaust pipe 40 is diffused into the expansion chambers 48, 50, 52.

  As shown in FIG. 7, the cross-sectional shape of the flat portion 40C of the exhaust pipe 40 viewed from the longitudinal direction (front and rear of the vehicle body) is such that the cross-sectional width (long axis) D1 in the vehicle width direction (lateral direction) is The cross section width (short axis) D2 in the longitudinal direction is wider and oval. The cross-sectional shape of the main muffler 14 viewed from the longitudinal direction (vehicle longitudinal direction) is such that the vehicle width direction (lateral direction) sectional width (long axis) E1 is the vehicle vertical direction (vertical direction) sectional width (short axis). ) The oval is wider than E2, and the flat portion 40C of the exhaust pipe 40 and the main muffler 14 have an oval shape with the major axis in the same direction, and preferably have a similar cross-sectional shape.

  Accordingly, the flat portion 40C of the exhaust pipe 40 and the main muffler 14 have the same expansion ratio (E1 / D1 = E2 / D2) with respect to the respective circumferential directions. As a result, an efficient expansion effect can be obtained as compared with expansion from a circular cross section to a flat cross section.

  The cross-sectional shape of the exhaust pipe 40 gradually changes from a circular shape to an elliptical shape from the flange 40A toward the main muffler 14, and the cross-sectional shape changes from an elliptical shape toward the flange 40B from the main muffler 14. It is gradually changing to a circle.

  Next, the operation of this embodiment will be described.

  In the present embodiment, as shown in FIG. 7, the flat portion 40 </ b> C of the exhaust pipe 40 passes through the main muffler 14, and the exhaust pipe 40 passes through the expansion chambers 48, 50, 52 of the main muffler 14. A plurality of through-holes 56 through which the exhaust passes are formed in the flat portion 40C. As a result, the exhaust from the engine is diffused from the flat portion 40 </ b> C of the exhaust pipe 40 into the expansion chambers 48, 50, 52 through the through hole 56. At this time, the exhaust pipe 40 is arranged coaxially with the axis P1 of the main muffler 14, and the flat portion 40C of the exhaust pipe 40 and the main muffler 14 have an elliptical similar cross-sectional shape with the major axis in the same direction. It has become.

  That is, the flat portion 40C of the exhaust pipe 40 and the main muffler 14 have the same expansion ratio (E1 / D1 = E2 / D2) with respect to the entire circumferential direction. For this reason, since an efficient expansion effect can be obtained as compared with the expansion from the circular cross section to the flat cross section, the exhaust noise can be effectively reduced and the noise reduction performance is improved.

  In the present embodiment, the muffler performance is improved, so that the sub-muffler can be eliminated. Further, when the sub-muffler can be eliminated, the entire length of the exhaust system 10 can be shortened by the length.

  Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art. For example, in each of the above embodiments, the cross-sectional shape of the flat portion 30 of the exhaust pipe 24 and the cross-sectional shape of the flat portion 40C of the exhaust pipe 40 are elliptical, but other flat shapes such as an ellipse are used instead of the elliptical shape. Also good. An ellipse is a figure in which both ends of two parallel sides are connected by a semicircle, unlike an ellipse.

  Further, in the first embodiment, the flat portion 30 is configured by three portions, that is, the front portion 32, the central portion 34, and the rear portion 36, whose flat cross-sectional shape is rotated 90 degrees around the axis of the exhaust pipe 24. Instead of this, the flat part 30 may be constituted by two parts of the front part 32 and the central part 34. Further, the flat portion 30 may be constituted by four or more portions whose flat cross-sectional shapes are each rotated 90 degrees around the axis of the exhaust pipe 24.

  Moreover, it is good also as a structure which combined 1st Embodiment and 2nd Embodiment.

1 is a schematic perspective view of an exhaust pipe structure according to a first embodiment of the present invention, seen from an oblique front of a vehicle body. 1 is a schematic side view showing an exhaust pipe structure according to a first embodiment of the present invention. FIG. 3 is an enlarged cross-sectional view taken along line 3-3 in FIG. 2. FIG. 4 is an enlarged cross-sectional view taken along line 4-4 of FIG. FIG. 5 is an enlarged sectional view taken along line 5-5 in FIG. It is the schematic perspective view seen from the vehicle body diagonally front which shows the exhaust pipe structure which concerns on 2nd Embodiment of this invention. FIG. 7 is an enlarged cross-sectional view taken along line 7-7 in FIG.

Explanation of symbols

10 Exhaust system 12 Catalytic converter 14 Main muffler (second flat part)
16 Tail pipe 20 Exhaust pipe 22 Exhaust pipe 24 Exhaust pipe 24B Circular cross section of exhaust pipe 30 Flat part of exhaust pipe 32 Front part of flat part (first flat part)
34 Central part of flat part (2nd flat part, 1st flat part)
36 Rear part of the flat part (second flat part)
40 Exhaust pipe 40C Flat part of exhaust pipe (first flat part)
56 Exhaust pipe through hole

Claims (3)

A first flat portion whose cross-sectional shape is a flat cross section having a predetermined direction as a major axis and a direction orthogonal to the major axis as a minor axis;
An exhaust pipe structure comprising: a second flat portion that communicates with the first flat portion and at least one of a long axis and a short axis is expanded with respect to the first flat portion.   The second flat portion is connected in series to the first flat portion, and includes a portion having a major axis in a direction orthogonal to the long axis of the first flat portion, and the same tube internal section as the first flat portion The exhaust pipe structure according to claim 1, wherein the exhaust pipe structure has an area.   The first flat part is inserted into the second flat part, and the first flat part and the second flat part have a similar cross-sectional shape having a major axis in the same direction. Exhaust pipe structure as described.

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