JP6136975B2 - Exhaust structure - Google Patents

Description

  The present invention relates to an exhaust structure.

  Generally, in an automobile, an exhaust structure including a catalytic converter, a center pipe, a muffler, and the like is provided in the lower part of the vehicle body as an engine exhaust system. In such an exhaust structure, the center pipe is disposed below the fuel tank to avoid the fuel tank, and the inlet pipe extending from the center pipe to the rear muffler extends obliquely upward from the center pipe to avoid the rear suspension. (Refer to Patent Document 1).

JP 2005-329758 A

  The exhaust structure according to the prior art has a piping structure in which the inlet pipe rises rearward from the center pipe to the rear muffler. Therefore, there is a possibility that water (hereinafter referred to as “residual water”) accumulates in the center pipe due to insufficient exhaust gas pressure when the engine is running at low speed or idling.

  For this reason, expensive materials with high corrosion resistance are used for the center pipe and the like, and the thickness of the pipe is increased to improve the rust prevention performance against residual water.

  On the other hand, there is a desire to reduce the cost of the exhaust structure by preventing or suppressing the generation of residual water by improving the drainage performance when the engine is running at a low speed.

  The present invention has been made in view of the above facts, and an object of the present invention is to provide an exhaust structure with improved drainage.

The invention according to claim 1 constitutes an exhaust system of the engine, a center pipe disposed in a lower portion of the vehicle body, a muffler provided on the downstream side of the center pipe, and a vehicle upper side from the center pipe toward the muffler. An exhaust passage extending from the lowest area of the center pipe toward the muffler, or extending in the vehicle upper side or in the horizontal direction. The exhaust passage is disposed on the vehicle lower side from the exhaust passage, and water remaining in the center pipe is removed from the muffler. And a drainage enhancing means for discharging residual water from the center pipe to the muffler when the engine is rotating at low speed or idling.

  In this exhaust structure, when the engine rotates at high speed, the pressure of the exhaust gas acting on the center pipe is high, and the residual water moves together with the exhaust gas from the center pipe to the muffler via the exhaust passage and the drain passage.

  When the engine is running at a low engine speed or idling, the pressure of the exhaust gas acting on the center pipe is reduced, but the flow velocity of the drainage passage is improved by the flow velocity increasing means. Further, the drainage passage communicates with the lowest region where residual water is accumulated in the center pipe. For this reason, the residual water existing in the center pipe moves to the muffler through the drainage passage.

  According to a second aspect of the present invention, in the first aspect of the present invention, the first chamber of the muffler with which the exhaust passage communicates, the downstream side of the first chamber, and the first chamber are communicated with the first chamber. Provided in the second chamber of the muffler to which the drainage passage is communicated, and the communication port of the first chamber and the second chamber, are closed when the engine is rotating at low speed or idling, and opened when the engine is rotating at high speed. An on-off valve.

  In this exhaust structure, since the high pressure of the exhaust gas acts on the center pipe when the engine rotates at a high speed, the high pressure also acts on the exhaust passage and the drain passage provided on the downstream side of the center pipe. As a result, a high pressure acts on the first chamber of the muffler, and the on-off valve provided at the communication port with the second chamber is opened. Accordingly, the exhaust gas can be moved also in the exhaust passage, and the residual water moves together with the exhaust gas to the muffler through the exhaust passage and the drain passage.

  On the other hand, when the engine is rotating at low speed or idling, the pressure of the exhaust gas acting on the center pipe decreases. In this case, the pressure acting on the exhaust passage provided on the downstream side of the center pipe is also reduced, and the on-off valve that connects the first chamber and the second chamber of the muffler is closed. As a result, the exhaust gas does not flow in the exhaust passage, and the exhaust gas flows only in the drain passage. That is, since the cross-sectional area of the channel is reduced on the downstream side of the center pipe, the flow rate of the drainage channel is improved, and the water remaining in the center pipe can be moved to the muffler.

  According to a third aspect of the present invention, in the first aspect of the present invention, the first chamber of the muffler to which the exhaust passage is communicated, and the first chamber that is provided downstream of the first chamber and communicates with the first chamber. A second chamber of the muffler to which the drainage passage is communicated, and a branch point where the center pipe branches into the exhaust passage and the drainage passage at the time of low rotation or idling rotation of the engine, and the first chamber The pressure difference between the branch point and the second chamber is larger than the pressure difference.

  In this exhaust structure, when the engine rotates at a high speed, a high pressure of exhaust gas acts on the center pipe, so that a high pressure also acts on an exhaust passage and a drain passage provided on the downstream side of the center pipe. As a result, the exhaust gas and the residual water move from the exhaust passage through the first chamber of the muffler to the second chamber or the drainage passage to the second chamber of the muffler. At this time, residual water also moves to the muffler through the exhaust passage and the drain passage.

  On the other hand, when the engine is rotating at low speed or idling, the pressure of the exhaust gas acting on the center pipe decreases. Therefore, it becomes impossible to move the residual water with the pressure of the exhaust gas lowered from the center pipe to the exhaust passage disposed on the vehicle upper side of the center pipe. At this time, the pressure difference from the branch point to the second chamber downstream of the first chamber is larger than the pressure difference from the branch point branching from the center pipe to the exhaust passage and the drain passage to the first chamber of the muffler. Therefore, even if the pressure of the exhaust gas acting on the center pipe decreases, the drainage passage can ensure a predetermined pressure difference between the branch point and the second chamber of the muffler. As a result, the residual water accumulated in the lowest region of the center pipe moves to the second chamber of the muffler through the drainage passage.

  According to a fourth aspect of the present invention, in the first or second aspect of the present invention, the exhaust passage and the drainage passage are formed by providing a partition member inside the tubular body on the downstream side of the center pipe.

  In this exhaust structure, the exhaust passage and the drainage passage can be easily formed only by providing a partition member inside the tube that connects the conventional center pipe and the muffler.

  Since the invention according to claims 1 to 3 has the above-described configuration, it is prevented / suppressed that water remains in the center pipe or the like when the engine is running at a low speed, and an expensive corrosion-resistant material is not used for rust prevention. I'll do it.

  Since invention of Claim 4 was set as the said structure, an exhaust passage and a drainage passage can be manufactured easily, and manufacturing cost can be suppressed.

1 is a schematic side view of an exhaust structure according to a first embodiment of the present invention. It is a longitudinal cross-sectional view which shows the principal part of the exhaust structure which concerns on 1st Embodiment of this invention. It is operation | movement explanatory drawing of the principal part of the exhaust structure which concerns on 1st Embodiment of this invention. It is a longitudinal cross-sectional view of the exhaust structure which concerns on the variation of 1st Embodiment of this invention. It is a longitudinal cross-sectional view of the exhaust structure which concerns on the variation of 1st Embodiment of this invention. It is a longitudinal cross-sectional view of the exhaust structure which concerns on the variation of 1st Embodiment of this invention. It is a longitudinal cross-sectional view of the exhaust structure which concerns on 2nd Embodiment of this invention.

[First Embodiment]

  An exhaust structure according to a first embodiment of the present invention will be described with reference to FIGS.

  Hereinafter, in each drawing, the front of the vehicle is indicated by an arrow FR, and the upper portion of the vehicle is indicated by an arrow UP. Moreover, the arrow in the figure indicates the flow of exhaust gas. Various components are attached to the inside of the exhaust structure, but only components related to the present embodiment are illustrated, and other components are not illustrated.

  As shown in FIG. 1, the exhaust structure 10 is connected to an exhaust manifold (not shown) provided in the engine 12 of the vehicle. The exhaust structure 10 includes a front pipe 14 connected to an exhaust manifold from the upstream side, catalytic converters 16 and 18 provided on the downstream side of the front pipe 14, and a center muffler that is a pre-muffler provided on the downstream side of the catalytic converter 18. 20, a center pipe 22 connected to the center muffler 20, an inlet pipe 24 provided on the downstream side of the center pipe 22, a rear muffler 26 that is a main muffler to which the inlet pipe 24 is connected, and an exhaust side of the rear muffler 26. And a tail pipe 28 provided.

  Each member constituting the exhaust structure 10 is disposed below the floor panel of the vehicle body. However, since the center pipe 22 is disposed below the fuel tank 30, a horizontal connection on the upstream (center muffler 20) side is provided. 22A, an inclined portion 22B that is bent obliquely downward at the downstream end of the connecting portion 22A, and a horizontal portion 22C that extends in the horizontal direction at a position one step lower than the connecting portion 22A from the lower end of the inclined portion 22B.

  The inlet pipe 24 is formed integrally with the center pipe 22 on the downstream side of the center pipe 22. As shown in FIG. 1, the inlet pipe 24 includes an inclined portion 24 </ b> A that rises obliquely rearward from the downstream end of the horizontal portion 22 </ b> C of the center pipe 22 in order to avoid a rear suspension 32 provided at the lower portion of the vehicle body. A horizontal portion 24B extending horizontally from the rear end of 24A toward the rear muffler 26 above the rear suspension 32;

  Thus, since the center pipe 22 is disposed below the fuel tank 30 and the inlet pipe 24 is disposed above the rear suspension 32, the height between the horizontal portion 22C of the center pipe 22 and the horizontal portion 24B of the inlet pipe 24 is increased. H has a height difference.

  Further, as shown in FIGS. 2 (A) and 2 (B), the inlet pipe 24 horizontally press-fits a partition member 36 into a tubular body 34 formed continuously with the same diameter as the center pipe 22. Therefore, the pipe 34 is divided into an exhaust passage 38 located on the upper side and a drainage passage 40 located on the lower side.

  In addition, the position (branch point P) where the pipe member 34 is branched into the exhaust passage 38 and the drainage passage 40 by the partition member 36 is a position lower than the connection portion 22A. A position lower than the connection portion 22A is defined as the lowest region A of the center pipe 22. In the lowest region A, the drainage passage 40 and the center pipe 22 are connected. The drainage passage 40 is preferably connected at the lowest position of the lowest region A.

  The inlet pipe 24 passes through a later-described second chamber 54 of the rear muffler 26 and is inserted to the first chamber 52. The exhaust passage 38 of the inlet pipe 24 opens to the first chamber 52, but the drainage passage 40 is closed at the end by a closing member 42. Further, a hole 44 is formed in the side surface of the pipe body 34 constituting the drainage passage 40 located in the second chamber 54 of the rear muffler 26. That is, the drainage passage 40 is communicated with the second chamber 54 of the rear muffler 26.

  As shown in FIG. 2A, the rear muffler 26 is provided with a partition wall 50 inside a rectangular box 46, whereby the inside of the box 46 communicates with the exhaust passage 38. The chamber 52 is divided into a second chamber 54 communicating with the drainage passage 40. The first chamber 52 and the second chamber 54 are communicated by a communication pipe 56 provided in the partition wall 50. Further, on the second chamber 54 side of the communication pipe 56, an on-off valve 58 urged in a direction that always closes the communication pipe 56 by an urging means (not shown) is provided. The on-off valve 58 includes a plate body 62 that is pivotally supported by the shaft body 60, and is configured such that the plate body 62 urged counterclockwise in the drawing by an urging means (not shown) closes the communication pipe 56. ing. Therefore, when the pressure difference between the first chamber 52 and the second chamber 54 exceeds a predetermined value, the opening / closing valve 58 is configured to be opened by the plate body 62 rotating clockwise against the urging force. is there.

  Further, as shown in FIG. 2A, the rear muffler 26 is provided with a tail pipe 28 having one end opened at the lower portion of the second chamber 54 and communicating with the outside through the first chamber 52. Yes.

  The operation of the exhaust structure 10 thus configured will be described.

  First, the case where the engine 12 is rotating at high speed will be described. In this case, exhaust gas from the engine 12 reaches the center pipe 22 via the front pipe 14, the catalytic converters 16 and 18, and the center muffler 20. In this case, since the rotational speed of the engine 12 is high, the pressure of the exhaust gas is high. Therefore, as shown in FIG. 3, high pressure also acts on the first chamber 52 of the rear muffler 26 via the exhaust passage 38. On the other hand, since the second chamber 54 of the rear muffler 26 communicates with the outside via the tail pipe 28, the pressure is lower than that of the first chamber 52. As a result, the pressure difference between the first chamber 52 and the second chamber 54 becomes a predetermined value or more, and the on-off valve 58 is opened.

  Therefore, the exhaust gas is discharged from the center pipe 22 to the second chamber 54 through the exhaust passage 38, the first chamber 52 of the rear muffler 26, and the communication pipe 56.

  Further, the exhaust gas is discharged from the center pipe 22 to the second chamber 54 of the rear muffler 26 through the drainage passage 40 and the hole 44 provided on the side surface of the pipe body 34.

  Here, when the rotational speed of the engine 12 is high, a sufficiently high exhaust gas pressure is acting on the center pipe 22, so the exhaust gas pressure acting on the exhaust passage 38 and the drainage passage 40 is also high, and the high flow rate is high. can get.

  Accordingly, the residual water W accumulated below the center pipe 22 (horizontal portion 22C) rises in the height difference H of the inclined portion 24A of the drainage passage 40, and passes through the hole 44 provided on the side surface of the horizontal portion 24B to the second chamber 54. Falls (moves).

  Thus, when the engine 12 is rotating at a high speed, the pressure difference between the center pipe 22 and the rear muffler 26 is sufficient even if both the exhaust passage 38 and the drainage passage 40 are used by opening the on-off valve 58. Big. Therefore, the residual water W accumulated in the center pipe 22 can be discharged to the rear muffler 26 regardless of the height difference H between the horizontal portion 22C of the center pipe 22 and the horizontal portion 24B of the inlet pipe 24.

  Next, a description will be given of when the engine 12 is rotating at low speed or idling.

  When the rotational speed of the engine 12 decreases, the pressure of the exhaust gas acting on the center pipe 22 decreases. Further, the pressure acting on the first chamber 52 of the rear muffler 26 via the exhaust passage 38 is reduced. As a result, the pressure difference between the second chamber 54 and the first chamber 52 communicating with the outside via the tail pipe 28 is reduced, and the on-off valve 58 is closed.

  As a result, only the drainage passage 40 allows the center pipe 22 and the second chamber 54 of the rear muffler 26 to communicate with each other. Therefore, compared with the case where both the exhaust passage 38 and the drainage passage 40 are available, the cross-sectional area of the flow path is reduced, and the flow rate of the exhaust gas in the drainage passage 40 is increased. As a result, regardless of the height difference H between the horizontal portion 22C of the center pipe 22 and the horizontal portion 24B of the inlet pipe 24, the residual water W accumulated in the lowest region A of the center pipe 22 is discharged to the rear muffler 26 through the drainage passage 40. can do.

  When the engine 12 is rotating at a high speed, the on-off valve 58 is opened so that a large amount of exhaust gas is efficiently discharged to the rear muffler 26 and the residual water W in the center pipe 22 is discharged from the drainage passage 40 to the second chamber 54 of the rear muffler 26. Can be discharged. Further, when the engine 12 is rotating at a low speed or idling, the flow rate of the drainage passage 40 can be increased by closing the opening / closing valve 58 to reduce the cross-sectional area of the inlet pipe 24. As a result, the residual water W in the center pipe 22 can be discharged into the second chamber 54 of the rear muffler 26.

  In particular, since one end of the drainage passage 40 is open to the lowest region A of the center pipe 22, the residual water W accumulated in the lowest region A is reliably guided into the drainage passage 40, and the second chamber 54 of the rear muffler 26. To be discharged.

  As described above, in the exhaust structure 10, the residual water W in the center pipe 22 can be discharged to the rear muffler 26 regardless of the rotational speed of the engine 12, so that it is not necessary to adopt a rust prevention structure for the residual water W in the center pipe 22. It is not necessary to use a material having a high anticorrosion property.

  Further, since the on-off valve 58 is closed when the engine 12 is rotating at low speed or idling, the first chamber 52 of the rear muffler 26 becomes a resonance chamber and the exhaust passage 38 becomes a resonance tube. Here, in order to mute the low-frequency exhaust sound during idling rotation, it is necessary to increase the volume of the resonance chamber (first chamber 52). However, in the exhaust structure 10, the exhaust passage 38 has a length from the first chamber 52 of the rear muffler 26 to the horizontal portion 22 </ b> C of the center pipe 22. Therefore, it is possible to mute or suppress noise during idling rotation without increasing the volume of the rear muffler 26 (first chamber 52).

  In addition, although the threshold value of the high rotation and the low rotation of the engine referred to in the present embodiment depends on the vehicle type and the piping shape, it is 1500 rpm to 2000 rpm.

[Variation of the first embodiment]

  Note that the following can be considered as variations of the exhaust structure 10 according to the present embodiment. That is, as shown in FIG. 4, it can be considered that the opening / closing valve 58 is provided at the end of the exhaust passage 38 (inlet pipe 24) instead of being provided in the communication pipe 56.

  Further, as shown in FIG. 5, it is conceivable to form the exhaust passage 38 and the drain passage 40 with different pipes. That is, the inlet pipe 24 is used as the exhaust passage 38, and the drain pipe 66 is disposed below the inlet pipe 24 in parallel with the inlet pipe 24. While exhibiting the same effect as the first embodiment, the drainage performance of the engine 12 at the time of low rotation is further improved by forming the drainage pipe 66 to have a channel cross-sectional area smaller than that of the exhaust passage 38. be able to.

  Further, in this embodiment, the exhaust passage 38 and the drainage passage 40 are provided inside the pipe body 34 by providing the partition member 36 inside the inlet pipe 24. However, as shown in FIG. It can be considered that the pipe body 34 is formed as a double pipe by providing the pipe body 64. The inside of the pipe body 64 is an exhaust passage 38, and the space between the pipe body 64 and the pipe body 34 is a drainage passage 40. Note that, at the end of the inlet pipe 24, the pipe body 64 is expanded in diameter and joined to the pipe body 34, thereby closing the end of the drainage passage 40.

[Second Embodiment]

  An exhaust structure according to a second embodiment of the present invention will be described. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 7, the exhaust structure 70 includes an inlet pipe 24 disposed above the rear suspension 32 and a drain pipe 72 disposed below the rear suspension 32 on the downstream side of the center pipe 22. Prepare.

  The inlet pipe 24 has the same diameter as the center pipe 22 and is formed integrally with the center pipe 22. As shown in FIG. 7, the inlet pipe 24 includes an inclined portion 24 </ b> A that rises obliquely rearward from the downstream end of the horizontal portion 22 </ b> C of the center pipe 22 in order to avoid the rear suspension 32 provided at the lower portion of the vehicle body. A horizontal portion 24B extending horizontally from the rear end of 24A on the rear suspension 32, an inclined portion 24C inclined downward from the rear end of the horizontal portion 24B, and a horizontal portion extending from the lower end of the inclined portion 24C. A horizontal portion 24D extending to the first chamber 52 of the rear muffler 26.

  On the other hand, the drain pipe 72 is disposed below the rear suspension 32, extends in the horizontal direction from the lowest region A of the center pipe 22, and communicates with the second chamber 54 of the rear muffler 26. Note that the pipe diameter of the drain pipe 72 is smaller than the pipe diameter of the inlet pipe 24 so that the drain pipe 72 can be routed below the rear suspension 32.

  The operation of the exhaust structure 70 thus configured will be described.

  Since the high pressure of the exhaust gas acts on the center pipe 22 at the time of high engine rotation, a high pressure acts on the inlet pipe 24 and the drain pipe 72.

  Therefore, in the inlet pipe 24 serving as an exhaust passage, the residual water W in the center pipe 22 rises to the horizontal portion 24B regardless of the height difference H, and enters the first chamber 52 of the rear muffler 26 via the inclined portion 24C and the horizontal portion 24D. Moving. At the same time, the residual water W in the center pipe 22 moves from the center pipe 22 to the second chamber 54 of the rear muffler 26 via the drain pipe 72.

  On the other hand, when the engine 12 is rotating at low speed or idling, the pressure of the exhaust gas acting on the center pipe 22 is low, so the pressure of the exhaust gas acting on the inlet pipe 24 is also low. As a result, the residual water W in the center pipe 22 cannot reach the horizontal portion 24B by ascending the inclined portion 24A (height difference H) of the inlet pipe 24.

  On the other hand, in the rear muffler 26, the pressure in the second chamber 54 where the tail pipe 28 communicates with the outside on the downstream side of the first chamber 52 is lower than that of the first chamber 52 on the upstream side.

  As a result, the pressure difference between the branch point P on the downstream end side of the center pipe 22 and the second chamber 54 becomes larger than the pressure difference between the branch point P and the first chamber 52. Moreover, the diameter (flow-path cross-sectional area) of the drain pipe 72 is small compared with the inlet pipe 24 (exhaust passage 38). Further, the drain pipe 72 extends in the horizontal direction from the lowest region A of the center pipe 22 to the second chamber 54 of the rear muffler 26. Therefore, even if the pressure of the exhaust gas acting on the center pipe 22 decreases, the residual water W in the center pipe 22 flows through the drain pipe 72 and is discharged into the second chamber 54 of the rear muffler 26.

  In this way, separately from the inlet pipe 24 disposed on the upper side of the rear suspension 32, the drain pipe 72 having a diameter smaller than that of the inlet pipe 24 is routed below the rear suspension 32, so that the rotational speed of the engine 12 is increased. The residual water W of the center pipe 22 can be drained through the drain pipe 72 when the water level is low.

  As described above, in the exhaust structure 70, the residual water W in the center pipe 22 can be discharged to the rear muffler 26 regardless of the rotational speed of the engine 12, so that it is not necessary to adopt a rust prevention structure for the residual water W in the center pipe 22 and it is expensive. It is not necessary to use a material having a high anticorrosion property.

  Although the drain pipe 72 extends in the horizontal direction from the lowest region A of the center pipe 22 to the rear muffler 26, the drain pipe 72 may be formed to be inclined downward on the rear muffler 26 side. Further, even if the drain pipe 72 is inclined upward toward the rear muffler 26, the residual water W increases due to the pressure difference between the second chamber 54 and the branch point P of the center pipe 22 when the engine 12 is rotating at low speed or idling. Any tilt that can be moved (movable) is also included in this embodiment.

10, 70 Exhaust structure 22 Center pipe 26 Rear muffler (muffler)
36 Partition member 38 Exhaust passage 40 Drain passage 58 On-off valve (drainage enhancing means)
52 1st chamber 54 2nd chamber 72 Drainage pipe (drainage enhancement means)
A Minimum area P Branch point

Claims (4)

A center pipe that constitutes the exhaust system of the engine and is disposed at the bottom of the vehicle body,
A muffler provided on the downstream side of the center pipe;
An exhaust passage extending upward from the center pipe toward the muffler;
A drainage passage that extends from the lowest region of the center pipe toward the muffler in the vehicle upper side or in the horizontal direction, is disposed on the vehicle lower side from the exhaust passage, and drains water remaining in the center pipe to the muffler.
Drainage enhancing means for discharging residual water of the center pipe to the muffler at the time of low rotation of the engine or idling rotation,
Exhaust structure with. A first chamber of the muffler with which the exhaust passage communicates;
A second chamber of the muffler provided on the downstream side of the first chamber and communicated with the first chamber and the drainage passage;
An on-off valve that is provided at a communication port between the first chamber and the second chamber, is closed during low rotation of the engine or idling rotation, and is opened during high rotation of the engine;
The exhaust structure according to claim 1. A first chamber of the muffler to which the exhaust passage communicates;
A second chamber of the muffler provided on the downstream side of the first chamber and communicated with the first chamber and the drainage passage;
And at the time of low rotation of the engine or idling rotation, the branch point, the second chamber, and the pressure difference between the branch point where the center pipe branches into the exhaust passage and the drain passage and the first chamber The exhaust structure according to claim 1, wherein the pressure difference of   3. The exhaust structure according to claim 1, wherein the exhaust passage and the drainage passage are formed by providing a partition member inside the tubular body at a downstream side of the center pipe.

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