JP6493180B2 - Exhaust pipe for engine - Google Patents

Description

  The present invention relates to an exhaust pipe for an engine.

  An engine exhaust pipe attached to a vehicle may be provided with an inclined pipe portion that extends obliquely upward toward the rear of the vehicle in order to avoid structures such as a rear suspension (for example, Patent Document 1).

JP-A-10-131745

  By the way, when the exhaust gas discharged from the internal combustion engine is cooled, the water vapor in the exhaust gas is liquefied to generate condensed water, and the condensed water is accumulated in the lower part in the exhaust pipe. The condensed water accumulated in the exhaust pipe moves in the exhaust pipe in the exhaust downstream direction due to the flow of the exhaust, but if there is an inclined pipe portion as described above, the condensed water is unlikely to exceed the inclined pipe portion, It becomes more difficult to move to the exhaust downstream side than the inclined pipe portion, and the amount of condensed water discharged from the opening at the end of the exhaust pipe is reduced. Therefore, the drainage property of the condensed water from an exhaust pipe will fall.

  When the drainage of condensed water is reduced in this way, for example, there is a risk that the cross-sectional area of the exhaust passage in the exhaust pipe will decrease or the inside of the exhaust pipe may be blocked due to freezing of the condensed water due to a decrease in the outside air temperature. There is.

  Incidentally, in the exhaust pipe described in Document 1, a hole for discharging condensed water is provided in the middle of the exhaust pipe. However, if such a hole is provided, the exhaust gas leaks in the middle of the exhaust pipe, so that the flow of exhaust gas in the exhaust pipe is weakened. Therefore, the amount of condensed water discharged from the opening at the end of the exhaust pipe is reduced, and the drainage of condensed water may be deteriorated.

  The present invention has been made in view of such circumstances, and a problem to be solved is to provide an exhaust pipe for an engine that can improve drainage of condensed water accumulated in the pipe.

  An exhaust pipe that solves the above problem is an exhaust pipe for an engine that is attached to a vehicle, and is provided at a straight pipe portion and an exhaust downstream end of the pipe portion, and extends obliquely upward toward the rear of the vehicle. And an inclined pipe portion. And the protrusion which protrudes toward the inner side of the said pipe part is provided in the wall surface below the vehicle in the said pipe part.

  According to this configuration, the condensed water moves in the exhaust pipe due to the flow of the exhaust gas. When the condensed water reaches the projection of the pipe portion, the condensed water is splashed by the projection and peeled off from the wall surface of the projection. Here, since the projection serves as a throttle portion in the exhaust pipe, the flow velocity is increased when the exhaust passes through the projection. Therefore, the separated condensed water is sent to the exhaust downstream side together with the exhaust gas while being accelerated by the exhaust gas having an increased flow velocity, so that the condensed water easily flows to the exhaust downstream side beyond the inclined pipe portion. Become. Therefore, according to the same structure, the drainage property of the condensed water collected in a pipe | tube improves.

The side view which shows the exhaust system of the vehicle provided with the exhaust pipe for engines of one Embodiment. FIG. 2 is a plan view showing an exhaust system when the vehicle is viewed from above. Sectional drawing of the exhaust pipe which expanded the A section shown in FIG. Sectional drawing of an exhaust pipe along the BB line shown in FIG. The fragmentary sectional view of the exhaust pipe for demonstrating the motion of the condensed water in the exhaust pipe of the embodiment. The fragmentary sectional view of the exhaust pipe for demonstrating the motion of the condensed water in the exhaust pipe of the embodiment. Sectional drawing which shows the structure of the exhaust pipe in the modification of the embodiment.

Hereinafter, an embodiment of an exhaust pipe for an engine attached to a vehicle will be described with reference to FIGS.
In each figure, the front of the vehicle is indicated by an arrow FR, and the upward direction of the vehicle is indicated by an arrow UP.

  As shown in FIGS. 1 and 2, an internal combustion engine 10 is mounted on the front portion of the vehicle 100. An exhaust manifold 20 is connected to the exhaust port of the internal combustion engine 10. A catalyst device 30 for purifying exhaust gas is connected to the exhaust downstream end of the exhaust manifold 20. A first exhaust pipe 41 through which exhaust gas that has passed through the catalyst device 30 flows is connected to the exhaust gas downstream end of the catalyst device 30. A well-known exhaust heat recovery unit 50 is connected to the exhaust downstream end of the first exhaust pipe 41 to raise the temperature of the engine coolant using the heat of the exhaust. A second exhaust pipe 42 is connected to the exhaust downstream end of the exhaust heat recovery device 50. A silencer 60 for reducing exhaust noise is connected to the exhaust downstream end of the second exhaust pipe 42. The exhaust heat recovery device 50, the second exhaust pipe 42, and the silencer 60 are suspended from the under floor of the vehicle 100.

The second exhaust pipe 42 includes a first pipe part 42A to a fifth pipe part 42K and a first bent part 42B to a fifth bent part 42L.
The first pipe portion 42A is a straight pipe extending in the vehicle front-rear direction from the exhaust downstream end of the exhaust heat recovery device 50. The second exhaust pipe 42 is connected to the exhaust downstream end of the first pipe portion 42A. A first bent portion 42B for bending in the direction is provided. A straight second pipe portion 42C extending in the vehicle width direction is provided at the exhaust downstream end of the first bent portion 42B.

  A second bent portion 42D for bending the second exhaust pipe 42 bent in the vehicle width direction toward the vehicle longitudinal direction again is provided at the exhaust downstream end of the second pipe portion 42C. A straight third pipe portion 42E extending in the vehicle front-rear direction is provided at the exhaust downstream end of the portion 42D.

  In order to avoid the second exhaust pipe 42 from hitting the suspension device for suspending the rear wheel 110 of the vehicle 100 at the exhaust downstream end of the third pipe portion 42E, the second exhaust pipe 42 is inclined upwardly toward the rear of the vehicle. A third bent portion 42F is provided for bending. A fourth pipe portion 42G that extends obliquely upward toward the rear of the vehicle is provided at the exhaust downstream end of the third bent portion 42F. By providing the third bent part 42F and the fourth pipe part 42G in the second exhaust pipe 42, the second exhaust pipe 42 is provided at the exhaust downstream end of the third pipe part 42E and faces the rear of the vehicle. An inclined pipe portion K extending obliquely upward is formed.

  A fourth bent portion 42H is provided at the exhaust downstream end of the fourth pipe portion 42G to bend the second exhaust pipe 42 extending obliquely upward toward the rear of the vehicle obliquely downward toward the rear of the vehicle. A fifth pipe portion 42K that extends obliquely downward toward the rear of the vehicle is provided at the exhaust downstream end of the fourth bent portion 42H.

  A fifth bent portion 42L for bending the second exhaust pipe 42 extending obliquely downward toward the rear of the vehicle toward the silencer 60 is provided at the exhaust downstream end of the fifth pipe portion 42K. A straight sixth pipe portion 42M connected to the silencer 60 is provided at the exhaust downstream end of the fifth bent portion 42L. The exhaust downstream end of the sixth pipe portion 42M is opened in the silencer 60.

  As shown in FIGS. 3 and 4, a conical protrusion 70 protruding toward the inside of the third pipe portion 42 </ b> E is provided on the wall surface of the third pipe portion 42 </ b> E below the vehicle. More specifically, the protrusion 70 is provided at a position close to the inclined pipe portion K in the third pipe portion 42E, and the wall of the lowest point in the vertical direction of the third pipe portion 42E is recessed toward the inside of the pipe. It is formed by.

  As shown in FIG. 4, the protrusion amount of the protrusion 70 from the inner wall of the third pipe portion 42E is such that even if a maximum amount of condensate is accumulated in the tube of the third pipe portion 42E, the tip of the protrusion 70 is It sets so that it may come out of the water surface WS of condensed water.

Next, the operation of the second exhaust pipe 42 of the present embodiment will be described.
First, when the exhaust discharged from the internal combustion engine 10 passes through the exhaust heat recovery device 50, heat transfer from the exhaust to the cooling water occurs during the passage, so that the exhaust is cooled.

When the exhaust gas is cooled in this way, the water vapor in the exhaust gas is liquefied and condensed water is generated, and the condensed water is accumulated in the lower part of the second exhaust pipe 42.
As shown in FIG. 5, the condensed water W accumulated in the second exhaust pipe 42 moves in the second exhaust pipe 42 in the exhaust downstream direction by the flow of the exhaust, and the protrusion 70 of the third pipe portion 42E. The condensed water W is splashed up by the protrusions 70. Then, the tip of the condensed water W bounced off is peeled off from the wall surface of the protrusion 70. Here, since the projection 70 becomes a throttle portion in the second exhaust pipe 42, the flow rate of the exhaust is increased when the exhaust passes through the projection 70.

  As shown in FIG. 6, the separated condensed water WH (hereinafter, condensed water separated from the projection 70 is referred to as condensed water WH) is accelerated by the exhaust having an increased flow rate and sent to the exhaust downstream side together with the exhaust. Thus, the condensed water WH easily flows over the inclined pipe portion K to the exhaust downstream side. The condensed water WH that has flowed to the exhaust downstream side beyond the inclined pipe portion K is then discharged into the silencer 60 from the exhaust downstream end of the sixth pipe portion 42M. Thus, the condensed water in the second exhaust pipe 42 is discharged into the silencer 60, so that, for example, the passage cross-sectional area of the exhaust in the second exhaust pipe 42 is reduced by freezing of the condensed water, or the second exhaust pipe Occurrence of an inconvenience that the inside of 42 is blocked by freezing of condensed water is suppressed.

  Further, as described above, the protrusion 70 is a throttle portion in the second exhaust pipe 42, and the exhaust passage cross-sectional area is small in the throttle portion. Therefore, such a throttle portion becomes a resistance when the sound energy of the exhaust passes through the pipe, and as a result, the exhaust sound is lowered.

  Incidentally, when the projection 70 is provided on the first pipe portion 42A, the exhaust flow is weakened when the exhaust passes through the first bent portion 42B provided at the exhaust downstream end of the first pipe portion 42A. The momentum when the condensed water accelerated when passing through 70 flows with the exhaust gas is weakened. Therefore, even if the condensed water is peeled off from the wall surface by the protrusion 70, the peeled condensed water may adhere to the inner wall of the second exhaust pipe 42 before reaching the inclined pipe portion K. Similarly, when the projection 70 is provided on the second pipe portion 42C, the exhaust flow is weakened when the exhaust passes through the second bent portion 42D provided at the exhaust downstream end of the second pipe portion 42C. The momentum of the condensed water that is accelerated when passing through the protrusion 70 flows with the exhaust gas is also weakened. Therefore, in this case as well, even if the condensed water is separated from the wall surface by the protrusion 70, the separated condensed water may adhere to the inner wall of the second exhaust pipe 42 before reaching the inclined pipe portion K. .

  In this regard, in the above embodiment, the projection 70 is provided on the above-described third pipe portion 42E, and the exhaust pipe between the projection 70 and the inclined pipe portion K is linear. When the exhaust gas flows through the exhaust pipe, the flow of the exhaust gas is unlikely to drop. Accordingly, the condensed water WH accelerated when passing through the projection 70 reaches the inclined pipe portion K while maintaining the momentum flowing along with the exhaust, and the condensed water WH passes through the inclined pipe portion K and is exhausted. It becomes easy to flow downstream.

  Further, the protrusion 70 is provided at a position close to the inclined tube portion K in the third tube portion 42E. Therefore, compared with the case where the projection 70 is provided at a position farther from the inclined pipe part K in the third pipe part 42E, that is, at a position upstream of the exhaust gas in the third pipe part 42E, the condensation when the inclined pipe part K is reached. The momentum of the water WH remains stronger. For this reason, the condensed water WH easily flows over the inclined pipe portion K to the exhaust downstream side for these reasons.

As described above, according to the present embodiment described above, the following effects can be obtained.
(1) Since the condensate WH easily flows to the exhaust downstream side beyond the inclined pipe portion K by providing the projection 70 on the third pipe portion 42E, the drainage of the condensate collected in the second exhaust pipe 42 Will be improved.

(2) Since the exhaust noise is lowered by providing the projection 70, the noise reduction performance of the exhaust is improved.
In addition, the said embodiment can also be changed and implemented as follows.

-Although the shape of the protrusion 70 was conical, other shapes such as a pyramid may be used.
The protrusion 70 is formed by denting the wall surface of the third tube portion 42E toward the inside of the tube, but the protrusion 70 may be provided on the third tube portion 42E in other modes. For example, a separately formed protrusion 70 may be fixed to the inner wall of the third pipe portion 42E.

  As shown in FIGS. 3 and 4, the protrusion 70 is formed by denting the wall surface of the lowest point in the vertical direction of the third pipe portion 42E toward the inside of the pipe. The protrusion 70 protrudes from the inner wall of the third pipe portion 42E. Even if the maximum amount of condensate is accumulated in the pipe of the third pipe portion 42E, the tip of the protrusion 70 is the water surface WS of the condensed water. Set to leave.

  Here, when the estimated amount of condensed water accumulated in the pipe of the third pipe portion 42E is very large, the protrusion amount of the protrusion 70 must be increased accordingly, and therefore the protrusion 70 is formed in the third pipe portion 42E. There is a risk of large exhaust resistance.

  Therefore, as shown in FIG. 7, not the lowest point L in the vertical direction of the third pipe portion 42E but the wall surface above the vehicle from the lowest point L is recessed toward the inside of the pipe to form the projection 70. You may do it. In this case, as compared with the above-described embodiment, the wall of the protrusion 70 is likely to come out from the water surface WS of the condensed water by moving the formation portion of the protrusion 70 upward in the vehicle. Therefore, even if the protrusion amount of the protrusion 70 is not increased so much, the protrusion 70 can be easily projected from the water surface WS of the condensed water. Therefore, it is possible to improve the drainage of condensed water while suppressing the protrusion 70 from becoming a large exhaust resistance in the third pipe portion 42E.

  In the exhaust system of the above embodiment, the exhaust heat recovery device 50 is connected to the exhaust upstream end of the second exhaust pipe 42. In addition, in the exhaust system in which another silencer different from the silencer 60 is connected to the exhaust upstream end of the second exhaust pipe 42 instead of the exhaust heat recovery device 50, when the outside air temperature is low, the outside air When the exhaust passes through the silencer having a relatively large contact area with the exhaust, the exhaust is cooled. Therefore, the water vapor in the exhaust gas is liquefied and condensed water is generated, and the condensed water is accumulated in the lower part in the second exhaust pipe 42. Therefore, also in the exhaust system in which the silencer is connected to the exhaust upstream end of the second exhaust pipe 42, the drainage of the condensed water accumulated in the exhaust pipe can be improved by providing the projection 70 as described above. It becomes like this.

  Even in an exhaust system in which a member for promoting exhaust cooling such as the exhaust heat recovery device 50 and the silencer is not connected to the exhaust upstream end of the second exhaust pipe 42, the temperature of the second exhaust pipe 42 itself is low when the outside air temperature is low. Therefore, the exhaust gas is cooled by the second exhaust pipe 42. Therefore, also in this case, the condensed water tends to accumulate in the lower part in the second exhaust pipe 42. Therefore, even in an exhaust system in which a member that promotes cooling of the exhaust is not connected to the exhaust upstream end of the second exhaust pipe 42, by providing the projection 70 as described above, the drainage of the condensed water accumulated in the exhaust pipe is improved. To be able to.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 20 ... Exhaust manifold, 30 ... Catalyst apparatus, 41 ... 1st exhaust pipe, 42 ... 2nd exhaust pipe, 42A ... 1st pipe part, 42B ... 1st bending part, 42C ... 2nd pipe part, 42D ... 2nd bent part, 42E ... 3rd pipe part, 42F ... 3rd bent part, 42G ... 4th pipe part, 42H ... 4th bent part, 42K ... 5th pipe part, 42L ... 5th bent part, 42M ... 6th pipe part, 50 ... Waste heat recovery device, 60 ... Silencer, 70 ... Projection, 100 ... Vehicle, 110 ... Rear wheel, K ... Inclined pipe part, W ... Condensed water, WH ... Condensed water, WS ... Water surface .

Claims (1)

An exhaust pipe for an engine attached to a vehicle,
A plurality of straight pipe sections;
Among the pipe parts, an inclined pipe part provided at the exhaust downstream end of the pipe part provided on the most downstream side of the exhaust gas and extending obliquely upward toward the rear of the vehicle is engine-cooled using the heat of the exhaust gas. It is located downstream of the exhaust heat recovery unit that raises the temperature of the water ,
An exhaust pipe for an engine, characterized in that a projection projecting toward the inside of the pipe portion is provided on a wall surface below the vehicle of the pipe portion provided on the most downstream side of the exhaust.

Images