JP2009121310A - Tail pipe structure of exhaust system of engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tail pipe structure of an exhaust system of an engine capable of improving mountability to a vehicle body frame by reducing the arrangement space of a tail pipe while reducing a pressure loss of an exhaust gas by ensuring a passage cross sectional area of the tail pipe. <P>SOLUTION: The pair of tail pipes 5a, 5b having a circular shape cross section are juxtaposed in the vertical direction, the front ends of both tail pipes 5a, 5b are welded to the downstream end of a casing 2, both tail pipes 5a, 5b are curved and formed in a circular shape toward the right side, and the rear end is opened to a right side part of the vehicle body frame F. A large passage cross sectional area is ensured by setting the tail pipes 5a, 5b as two pieces, and the arrangement space in planar view is reduced by providing tail pipes 5a, 5b side by side in the vertical direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a tail pipe structure of an exhaust system of an engine, and more particularly to a tail pipe connected to a casing disposed in the exhaust system.

  Exhaust gas pressure loss when flowing through the exhaust passage of the engine is an important condition that greatly affects engine performance and fuel consumption. (For example, refer to Patent Document 1). The tail pipe is connected to a casing such as a silencer or an exhaust purification device disposed in the exhaust passage of the engine, and exhausts exhaust gas after flowing in the casing in a predetermined direction. By using two pipes, the passage cross-sectional area is expanded to reduce pressure loss.

For example, FIG. 9 is a plan view showing a tail pipe structure of an exhaust system of an engine in the prior art of the same type as that of Patent Document 1, and FIG. 10 is a sectional view taken along line XX of FIG. The exhaust gas that has passed through the exhaust pipe 1 circulates in the casing 2 from the upper side to the lower side in the figure, and the exhaust gas after the circulation is discharged outward from the right side of the vehicle body frame F by the tail pipes 101a and 101b. In this conventional tail pipe structure, a pair of tail pipes 101 a and 101 b are provided side by side, and the front ends of both tail pipes 101 a and 101 b are welded to the downstream end of the casing 2. As a whole, both tail pipes 101a and 101b have a circular arc shape that is curved in the horizontal direction, and the rear ends of the tail pipes 101a and 101b open to the right side of the body frame F, respectively.
JP 2002-155741 A

However, the technique disclosed in Patent Document 1 has a problem that a large space is required for handling the tail pipes 101a and 101b.
That is, as is apparent from FIG. 9, the pair of tail pipes 101a and 101b are arranged on the outer peripheral side of the right tail pipes 101a and 101b that are curved with a small radius of curvature, and the left tail pipes 101a and 101b that are curved with a large radius of curvature. Therefore, a considerable space is required for handling in a plan view. For example, in trucks and buses, the engine exhaust system is installed in the vehicle body frame F together with traveling equipment such as fuel tanks and spare tires. Therefore, the engine exhaust system must be routed while avoiding interference with these traveling equipment. Must be set. For this reason, the exhaust system of the engine is required to reduce the handling space in plan view as much as possible, and naturally the handling space of the tail pipes 101a and 101b constituting a part of the exhaust system is also reduced. It will be necessary.

In the tail pipe structure of the above-mentioned Patent Document 1, the pair of tail pipes 101a and 101b requires a large handling space against such a demand, so that it is particularly limited to arrange traveling equipment around the tail pipe. As a result, there has been a problem that the mountability to the body frame F is deteriorated.
The present invention has been made to solve such problems, and the object of the present invention is to reduce the pressure loss of exhaust gas by securing the cross-sectional area of the tail pipe and to reduce the space for handling the tail pipe. It is an object to provide a tail pipe structure of an exhaust system of an engine that can reduce the size of the vehicle body and improve the mountability to the body frame.

  In order to achieve the above object, the invention of claim 1 is directed to an engine exhaust system tail pipe structure in which one end of a tail pipe is connected to a casing disposed in an exhaust passage of the engine and the other end of the tail pipe is opened to the atmosphere. In this case, the tail pipe is a single tail pipe having a flat cross-sectional shape in which the height dimension is enlarged with respect to the width dimension, or a plurality of tail pipes arranged in parallel in the vertical direction.

  Accordingly, a tail pipe having a flat cross-sectional shape whose height is enlarged with respect to the width dimension ensures a larger passage cross-sectional area as compared with a single tail pipe having a diameter corresponding to the width dimension, and also in the vertical direction. In the plurality of tail pipes arranged side by side, a larger passage cross-sectional area is secured as compared with one tail pipe having the same diameter, and the pressure loss of the exhaust gas when passing through the tail pipe is reduced.

In any case, the space for handling the tail pipe in a plan view is substantially the same as that of one tail pipe. For example, the tail pipe is arranged in comparison with the technique of Patent Document 1 in which a pair of tail pipes are provided side by side. However, the space is greatly reduced. Therefore, other traveling equipment can be easily arranged around the tail pipe.
According to a second aspect of the present invention, in the first aspect, the tail pipe is connected to the exhaust downstream end of the casing and curved in a horizontal direction substantially orthogonal to the longitudinal direction of the casing so that the other end faces the outside of the vehicle. It is not.

  Therefore, the tail pipe is curved in the horizontal direction and the other end faces the outside of the vehicle. Even when the tail pipe is curved in this way, one tail pipe has a height dimension with respect to the width dimension. By adopting an enlarged flat cross-sectional shape or arranging a plurality of tail pipes in the vertical direction, the pressure loss of the exhaust gas when passing through the tail pipe is reduced, and the tail pipe is managed in plan view. Space is reduced.

According to a third aspect of the present invention, in the first or second aspect, the tail pipe is a single tail pipe having a flat cross-sectional shape in which a height dimension is enlarged with respect to a width dimension, and the exhaust purification device is disposed in the tail pipe. It is what was contained.
Therefore, the tail pipe ensures a large passage cross-sectional area due to its flat cross-sectional shape, so that an exhaust purification device such as an oxidation catalyst accommodated in the casing can be accommodated in the tail pipe, thereby shortening the overall length of the casing. Thus, the arrangement of other traveling equipment in the vicinity is facilitated.

As described above, according to the tail pipe structure of the exhaust system of the engine of the first and second aspects of the invention, the exhaust pipe pressure loss is reduced by securing the passage cross-sectional area of the tail pipe, and the tail pipe handling space is reduced. Can be reduced to improve the mountability to the body frame.
According to the tail pipe structure of the exhaust system of the engine of the third aspect of the invention, in addition to the first or second aspect, by shortening the overall length of the casing, other traveling equipment can be easily arranged around the casing. Further, the mountability to the body frame can be further improved.

[First Embodiment]
Hereinafter, a first embodiment in which the present invention is embodied in a tail pipe structure of an exhaust system of an engine mounted on a truck will be described.
FIG. 1 is a plan view showing a tail pipe structure of an exhaust system of an engine of the present embodiment, and FIG. 2 is a sectional view taken along the line II-II in FIG. In FIG. 1, the upper portion corresponds to the front portion of the vehicle, and the right side portion of the vehicle body frame F is indicated by a broken line in FIG. In the following description, the front-rear direction and the left-right direction are expressed with reference to the vehicle.

  An exhaust pipe 1 extends rearward from an engine (not shown) mounted on the front of the vehicle. Although not shown, the exhaust pipe 1 has a casing containing a front-stage oxidation catalyst and a DPF (diesel particulate filter). Is provided. The rear end of the exhaust pipe 1 is connected to the upstream end of a cylindrical casing 2 extending in the front-rear direction. A selective reduction type NOx catalyst 3 is accommodated in the upstream side of the casing 2 and the downstream oxidation catalyst is located in the downstream side. 4 is housed.

Pre-stage oxidation catalyst, DPF, NOx catalyst 3 and the downstream side oxidation catalyst 4 functions as an exhaust purification device, DPF is collecting particulates in exhaust gas, NO ₂ pre-stage oxidation catalyst that is generated by oxidizing NO in the exhaust gas Is supplied onto the DPF, and the particulates deposited on the DPF are continuously incinerated by the oxidation reaction of NO ₂ (continuous regeneration). Further, in the operation region where the continuous regeneration of the DPF is not performed, before the DPF is clogged due to the accumulation of particulates, the unburned fuel supplied into the exhaust pipe 1 is burned to raise the temperature of the DPF and to reduce the particulates. Force incineration (forced regeneration). Further, the NOx catalyst 3 exhibits the NOx purification action of selectively reducing NOx in the exhaust gas to harmless N ₂ by using ammonia generated from an aqueous urea solution injected by an upstream injection nozzle (not shown). The post-stage oxidation catalyst 4 has an effect of oxidizing the excess ammonia and excess CO and HC during the forced regeneration of the DPF.

In the tail pipe structure of this embodiment, a pair of tail pipes 5 a and 5 b having a circular cross section are arranged in the vertical direction, and the front ends of both tail pipes 5 a and 5 b are welded to the downstream end of the casing 2. . As a whole, the tail pipes 5a and 5b are curved in a circular arc shape toward the right side, and the rear ends thereof are opened from the right side of the vehicle body frame F so as to face the outside.
The tail pipes 5a and 5b will be described in further detail. The tail pipes 5a and 5b are made of straight pipes having a circular cross section and are bent into an arc with the same predetermined radius of curvature by bending. Since these tail pipes 5a and 5b are arranged side by side vertically, in the plan view shown in FIG. 1, the lower tail pipe 5b is hidden by the upper tail pipe 5a. As a result, the handling space of both tail pipes 5a and 5b in plan view is as small as the handling space of one tail pipe that is curved and formed in the same shape.

The exhaust system of the engine such as the exhaust pipe 1, the casing 2, and the tail pipes 5a and 5b is mounted on the vehicle body frame F. The vehicle body frame F is provided with traveling equipment such as a fuel tank and a spare tire. Therefore, the exhaust system of the engine is routed on the vehicle body frame F while avoiding interference with these traveling equipment.
In the exhaust system of the engine configured as described above, exhaust gas from the engine is guided by the exhaust pipe 1 and introduced into the casing 2, and after passing through the NOx catalyst 3 and the rear-stage oxidation catalyst 4 in the casing 2, the tail pipe It is guided by 5a, 5b and discharged from the right side of the body frame F to the outside. Since the passage cross-sectional area in the tail pipes 5a and 5b is narrower than that in the casing 2, the exhaust gas is throttled in the casing 2, transferred to the tail pipes 5a and 5b, and further rearward in the tail pipes 5a and 5b. It is discharged outside after the transfer direction is changed from right to left. Therefore, the pressure loss of the exhaust gas when discharged from the casing 2 through the tail pipes 5a and 5b is greatly affected by the cross-sectional area of the tail pipes 5a and 5b, and the cross-sectional area of the tail pipes 5a and 5b is sufficiently secured. When not done, a large pressure loss occurs in this part.

  In the present embodiment, since the tail pipes 5a and 5b are double, a passage cross-sectional area approximately twice as large as that of one tail pipe 5a and 5b having the same diameter is secured. Therefore, the passage cross-sectional area of the tail pipes 5a and 5b, which greatly contributes to the pressure loss of the exhaust gas, is sufficiently secured, thereby reducing the pressure loss of the exhaust gas when circulating through the tail pipes 5a and 5b, and improving the engine performance and fuel consumption. be able to.

  Even if the diameter of the tail pipes 5a and 5b is increased, the cross-sectional area of the passage can be increased. However, as is well known, pipe bending is performed by extending the curved outer peripheral side while compressing the curved inner peripheral side of the pipe as the material. Therefore, as the pipe becomes larger in diameter and the difference in the radius of curvature between the inner and outer circumferences becomes larger, wrinkles are more likely to occur on the curved inner circumference side, making it difficult to process, and causing problems such as a decrease in productivity. When the tail pipes 5a and 5b are doubled, each pipe has a small diameter and can be easily bent. Thus, the above-described effects can be obtained after preventing adverse effects such as a decrease in productivity. it can.

On the other hand, although the tail pipes 5a and 5b are double as described above, the influence on the traveling equipment around the tail pipes 5a and 5b is far greater than, for example, the double tail pipes 101a and 101b of Patent Document 1. small.
That is, the exhaust system of the engine needs to be installed on the vehicle body frame F while avoiding interference with the traveling equipment. This also applies to the tail pipes 5a and 5b that constitute a part of the exhaust system. Here, while a loading platform or the like is mounted on the body frame F, it is necessary to secure a minimum ground clearance necessary for traveling below the body frame F. Large installation space in the direction cannot be secured, and the exhaust system and traveling equipment of the engine are inevitably arranged adjacent to each other in the front and back, or adjacent to the left and right, rather than being stacked one above the other. . Therefore, when determining the installation position of the engine exhaust system and traveling equipment on the vehicle body frame F, it is determined in consideration of the exhaust system handling space in plan view, the occupied space of the traveling equipment, and the like. It will be.

Accordingly, the tail pipes 5a and 5b also have a left side and a rear side of the tail pipes 5a and 5b as shown by a two-dot chain line in FIG. 1 rather than the necessity of installing other traveling equipment on the upper side or the lower side. There is much higher need to install traveling equipment on the road. For this reason, as in the technique of Patent Document 1, a pair of tail pipes 101a and 101b are juxtaposed in the left-right direction to reduce the handling space in side view, thereby facilitating the installation of other traveling equipment. Hardly contributes to this. On the other hand, in the present embodiment, since the pair of tail pipes 5a and 5b are arranged side by side in the vertical direction, the handling space in a plan view is greatly reduced. The traveling equipment can be installed on the left side of the tail pipes 5a, 5b or in the proximity of the rear. Therefore, the arrangement of other traveling equipment around the tail pipes 5a and 5b can be facilitated, and as a result, the mountability to the vehicle body frame F can be improved.
[Second Embodiment]
Next, a second embodiment in which the present invention is embodied in a tail pipe structure of another engine exhaust system will be described.

The tail pipe structure of the present embodiment is obtained by changing the shape of the tail pipe as compared with that of the first embodiment, and other configurations are the same as those of the first embodiment. Accordingly, parts having the same configuration are denoted by the same member numbers, description thereof is omitted, and differences are mainly described.
FIG. 3 is a plan view showing the tail pipe structure of the exhaust system of the engine of the present embodiment, and FIG. 4 is a sectional view taken along the line IV-IV in FIG.

  In the tail pipe structure of the present embodiment, instead of having two tail pipes 5a and 5b as in the first embodiment, a flat cross-sectional shape that is long in the vertical direction with the height dimension H enlarged with respect to the width dimension B is used. The passage cross-sectional area is secured by using one tail pipe 11. The cross-sectional shape of the tail pipe 11 will be described in more detail. The pair of upper and lower tail pipes 5a and 5b of the first embodiment shown in FIG. The front end of the tail pipe 11 is connected to the casing 2, the tail pipe 11 is curved in a circular arc shape toward the right side, and the rear end is opened to the right side of the vehicle body frame F.

The tail pipe 11 is bent by bending as in the first embodiment, except that a straight pipe having a flat cross-sectional shape is used as the material.
By setting the cross-sectional shape of the tail pipe 11 as described above, the passage cross-sectional area is further enlarged as compared with the tail pipes 5a and 5b of the first embodiment, so that the pressure loss of the exhaust gas can be further reduced.

In addition, while the passage cross-sectional area is enlarged from the tail pipes 5a and 5b of the first embodiment, the difference in the radius of curvature of the inner and outer circumferences when bent by bending is not different from that of the first embodiment, and easily Bending can be performed to prevent a decrease in productivity.
Further, while the passage cross-sectional area is enlarged, the space for handling the tail pipe 11 in plan view is as small as the tail pipes 5a and 5b of the first embodiment. Therefore, as in the first embodiment, the traveling equipment can be installed on the left side of the tail pipe 11 or in the vicinity of the rear side, and the arrangement of the other traveling equipment around the tail pipe 11 can be facilitated to make the vehicle body frame F It is possible to improve the mounting property.
[Third Embodiment]
Next, a third embodiment in which the present invention is embodied in the tail pipe structure of another engine exhaust system will be described.

The tail pipe structure of the present embodiment is that the rear-stage oxidation catalyst 4 is accommodated in the tail pipe 21 having a flat cross-sectional shape that is long in the vertical direction as in the second embodiment. It is the same as that of the embodiment. Accordingly, parts having the same configuration are denoted by the same member numbers, description thereof is omitted, and differences are mainly described.
FIG. 5 is a plan view showing the tail pipe structure of the exhaust system of the engine of this embodiment, and FIG. 6 is a sectional view taken along the line VI-VI in FIG.

In the present embodiment, corresponding to the extension of the tail pipe 21 for accommodating the rear-stage oxidation catalyst 4, the casing 2 is disposed closer to the center in the left-right direction of the vehicle body than in the first and second embodiments. Further, since the casing 2 does not need to accommodate the post-stage oxidation catalyst 4, its front-rear length is shortened.
As with the first embodiment, the tail pipe 21 is curved in a circular arc shape toward the right side, extends straight from the end of the curved region toward the right side, and opens to the right side of the vehicle body frame F. Further, the tail pipe 21 has a flat cross-sectional shape that is long in the vertical direction with the height dimension H enlarged with respect to the width dimension B, and the rear-stage oxidation catalyst 4 is accommodated in a straight line portion in the tail pipe 21. The tail pipe 21 having a flat cross-sectional shape that is long in the vertical direction has a much larger passage cross-sectional area than a normal tail pipe having a circular cross section, and thus can accommodate the rear-stage oxidation catalyst 4.

  Here, the passage cross-sectional area of the tail pipe 21 is narrower than that of the casing 2, and the capacity of the post-stage oxidation catalyst 4 that can be accommodated in the tail pipe 21 is limited as compared with the casing 2. However, when the NOx catalyst 3 is compared with the post-stage oxidation catalyst 4, the post-stage oxidation catalyst 4 is not required to have a capacity as large as the NOx catalyst 3 as is well known, and therefore has a cross-sectional area and length that can be accommodated in the tail pipe 21. The purification function required by the post-stage oxidation catalyst 4 can be sufficiently secured.

And according to the above tail pipe structure, although the overlapping description is not carried out, the effect similar to 2nd Embodiment can be acquired.
In addition, the total length of the casing 2 can be shortened by accommodating the rear-stage oxidation catalyst 4 in the tail pipe 21, and this factor also facilitates the arrangement of other traveling equipment and improves the mounting property to the body frame F. Contribute to doing. Further, if the longitudinal length of the casing 2 is not shortened, the longitudinal length of the NOx catalyst 3 accommodated in the casing 2 can be extended, thereby obtaining another advantage that the NOx purification performance can be improved.

  This is the end of the description of the embodiment, but the aspect of the present invention is not limited to this embodiment. For example, in each of the embodiments described above, the exhaust pipe tail pipe structure of the engine mounted on the truck is embodied, and the NOx catalyst 3 or the exhaust gas purifying device is installed in the casing 2 to which the tail pipes 5a, 5b, 11, 21 are connected. Although the rear-stage oxidation catalyst 4 is accommodated, the type of vehicle to be applied and the use of the casing 2 are not limited to this, and may be applied to, for example, a passenger car, and an expansion chamber or the like is provided inside the casing 2. You may comprise as a silencer.

  Further, in each of the above embodiments, the tail pipes 5a, 5b, 11 and 21 are connected to the exhaust downstream end of the casing 2 and curved toward the right side. However, the present invention is not limited to this. For example, as shown in FIG. 7, one end of a pair of tail pipes 31 a and 31 b that form a straight line may be connected to the outer peripheral surface of the casing 2, and the other end may be opened to the vehicle side portion. Even in this case, the same effect as that of the above embodiment can be obtained by arranging the pair of tail pipes 31a and 31b in the vertical direction. Furthermore, the number of tail pipes 5a, 5b, 31a, 31b is not limited to two, and may be three or more.

In each of the above embodiments, the tail pipes 5a, 5b, 11 and 21 are bent by bending. However, the method of bending the tail pipes 5a, 5b, 11 and 21 is not limited to bending. These parts may be welded together to produce tail pipes 5a, 5b, 11, 21 having a desired curved shape.
Further, the tail pipes 5a, 5b, and 11 are not necessarily bent sideways, and when there is a space behind the casing 2, the tail pipes 5a, 5b, and 11 are formed in a straight line so that the exhaust gas openings are arranged rearward. It may be directed diagonally downward, laterally, laterally diagonally downward, or downward. The pair of tail pipes may be a combination of the exhaust gas openings.

It is a top view which shows the tail pipe structure of the exhaust system of the engine of 1st Embodiment. It is the II-II sectional view taken on the line of FIG. It is a top view which shows the tail pipe structure of the exhaust system of the engine of 2nd Embodiment. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3. It is a top view which shows the tail pipe structure of the exhaust system of the engine of 3rd Embodiment. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5. It is a top view which shows the tail pipe structure of the exhaust system of another example engine. FIG. 8 is a view as viewed in the direction of arrow A in FIG. 7. It is a top view which shows the tail pipe structure of the exhaust system of the engine of a prior art. FIG. 10 is a sectional view taken along line XX in FIG. 9.

Explanation of symbols

1 Exhaust pipe (exhaust passage)
2 Casing 4 Back-stage oxidation catalyst (exhaust gas purification device)
5a, 5b, 11, 21, 31a, 31b Tail pipe H Height dimension B Width dimension

Claims (3)

In the tail pipe structure of the engine exhaust system in which one end of the tail pipe is connected to the casing disposed in the exhaust passage of the engine and the other end of the tail pipe is opened to the atmosphere.
Exhaust of an engine characterized in that the tail pipe is a single tail pipe having a flat cross-sectional shape having an enlarged height dimension with respect to a width dimension, or a plurality of tail pipes arranged in parallel in the vertical direction. System tail pipe structure.   The tail pipe is connected to an exhaust downstream end of the casing, and is curved in a horizontal direction substantially orthogonal to the longitudinal direction of the casing so that the other end faces the outside of the vehicle. The tail pipe structure of the exhaust system of the engine according to 1.   3. The tail pipe is a tail pipe having a flat cross-sectional shape having an enlarged height dimension with respect to a width dimension, and an exhaust purification device is accommodated in the tail pipe. Tail pipe structure of the engine exhaust system described.

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