CN211314352U - Engine exhaust system and buffer structure thereof - Google Patents

Abstract

The utility model discloses an engine exhaust system and a buffer structure thereof, the buffer structure comprises a connecting pipe and a flow guide piece arranged in the connecting pipe, the flow guide piece is arranged at the inlet section of the connecting pipe so as to divide the inlet section of the connecting pipe into two flow passage parts; the water conservancy diversion spare is platelike structure, including first water conservancy diversion section and second water conservancy diversion section, the terminal surface of first water conservancy diversion section with the entry end parallel and level of connecting pipe is followed the entry of connecting pipe is to the axis direction of its export, the thickness of second water conservancy diversion section is gradual increase earlier and is convergent again to will flow in the gas direction of connecting pipe the middle part position of connecting pipe export. The buffer structure is arranged between the exhaust pipe and the supercharger of the exhaust system, the structural design of the buffer structure can change the gas flow velocity distribution on the outlet section of the buffer structure, the flow velocity unevenness is reduced, and the impact of exhaust on the supercharger is reduced.

Description

Engine exhaust system and buffer structure thereof

Technical Field

The utility model relates to an engine technical field especially relates to an engine exhaust system and buffer structure thereof.

Background

Taking an 8-cylinder diesel engine as an example, a double-booster structure is adopted, wherein the burned exhaust gas of the 1 st, 2 nd, 3 th and 4 th cylinders is discharged into one booster, the burned exhaust gas of the 5 th, 6 th, 7 th and 8 th cylinders is discharged into the other booster, and generally, the 1 st and 4 th cylinders share one exhaust passage, and the 2 nd and 3 rd cylinders share one exhaust passage.

The ignition sequence of the 8-cylinder diesel engine is 1-6-2-4-8-3-7-5, the crankshaft angle of 270 degrees CA between exhaust of 1 cylinder and exhaust of 4 cylinders sharing one exhaust passage, the crankshaft angle of 450 degrees CA between exhaust of 4 cylinders and exhaust of 1 cylinder are identical, namely, the exhaust interval angle of each cylinder of the diesel engine is not uniform, which causes the problems that a supercharger is impacted by airflow, the supercharging efficiency is reduced, the fuel consumption rate is increased and the like.

It will be appreciated that the above problems may also exist for engines of other configurations, if the cylinder exhaust interval angle is not uniform.

In order to alleviate the problem of impact on the supercharger caused by uneven exhaust intervals of cylinders, a buffer device is added between an exhaust pipe and the supercharger at present, the buffer device generally comprises a pipe fitting for connecting the exhaust pipe and the supercharger, wherein two exhaust runners are arranged inside the exhaust pipe, so a guide plate is arranged inside the pipe fitting close to the exhaust pipe side to divide a connecting section of the pipe fitting and the exhaust pipe into runners corresponding to the two exhaust runners, and waste gas flowing into the two runners of the pipe fitting is mixed after passing through the guide plate and flows out of an outlet of the pipe fitting to an inlet of the supercharger.

In practical application, the flow velocity uniformity on the outlet section of the conventional buffer structure is poor, and the impact of different exhaust spacing angles on the supercharger cannot be effectively reduced.

In view of this, how to improve the existing buffer structure to reduce the flow velocity unevenness on the outlet cross section of the buffer structure and effectively reduce the impact on the supercharger caused by different exhaust spacing angles is a technical problem that needs to be solved by those skilled in the art.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing an engine exhaust system and buffer structure thereof, this buffer structure locate between exhaust system's blast pipe and the booster, and its structural design can change the gas flow velocity distribution on its export cross-section, reduces the velocity of flow unevenness, reduces the impact that the exhaust caused to the booster.

In order to solve the technical problem, the utility model provides a buffering structure of an engine exhaust system, which comprises a connecting pipe and a flow guide piece arranged in the connecting pipe, wherein the flow guide piece is arranged at the inlet section of the connecting pipe so as to divide the inlet section of the connecting pipe into two flow passage parts; the water conservancy diversion spare is platelike structure, including first water conservancy diversion section and second water conservancy diversion section, the terminal surface of first water conservancy diversion section with the entry end parallel and level of connecting pipe is followed the entry of connecting pipe is to the axis direction of its export, the thickness of second water conservancy diversion section is gradual increase earlier and is convergent again to will flow in the gas direction of connecting pipe the middle part position of connecting pipe export.

The buffering structure of the engine exhaust system is characterized in that the thickness of a second flow guide section of a flow guide piece arranged at the inlet section of a connecting pipe is set to be gradually increased and then gradually reduced from the gas flowing direction, thus, when the gas flowing in from the inlet of the connecting pipe flows through the flow guide piece, due to the structural design of the second flow guide section of the flow guide piece, the gas can deviate to the middle position of the outlet end of the connecting pipe to flow in the process of flowing to the outlet, compared with the existing buffer structure with the flow guide surface of the flow guide piece in a straight line structure, more gas deviates to the middle position of the outlet end of the connecting pipe, the difference between the gas flow velocity at the middle position of the outlet end of the connecting pipe and the gas flow velocity near the pipe wall can be reduced, and the unevenness of the flow velocity, therefore, the impact of the exhaust flowing out of the buffer structure on the supercharger of the engine exhaust system is reduced, the performance stability and the mechanical reliability of the supercharger are improved, and the performance and the reliability of the engine are further improved.

In the buffer structure, two opposite flow guide surfaces of the second flow guide section are both in an outwardly convex curve shape.

In the above buffer structure, the two flow guide surfaces are parabolic.

According to the buffer structure, the maximum linear distance of the parabolic opening of the flow guide surface is 10-16 mm.

According to the buffering structure, the connecting pipe comprises the first pipe section with the inlet, the second pipe section with the outlet and the transition pipe section for connecting the first pipe section and the second pipe section, and at least part of pipe wall of the transition pipe section is of an outwardly convex curve structure so as to guide the gas flowing into the connecting pipe to the middle position of the outlet of the connecting pipe.

In the buffering structure, the vertical distance between the inner end of the flow guide piece and the inlet end of the connecting pipe is h1, the vertical distance between the center point of the outlet end of the connecting pipe and the inlet end of the connecting pipe is h2, and h1/h2 is 0.5-0.54.

The utility model also provides an engine exhaust system, which comprises an exhaust pipe, a buffer structure and a supercharger, wherein the outlet of the exhaust pipe is connected with the outlet of the supercharger through the buffer structure; the exhaust pipe is provided with two exhaust flow passages; the buffer structure is the buffer structure described in any one of the above, and the two exhaust runners are respectively communicated with the two runner portions.

Since the above-described buffer structure has the above-described technical effects, the engine exhaust system including the buffer structure also has the same technical effects, and the discussion thereof will not be repeated here.

Drawings

FIG. 1 is a block diagram of an embodiment of an engine exhaust system according to the present invention;

fig. 2 is a schematic structural diagram of a first embodiment of a buffer structure of an engine exhaust system according to the present invention;

fig. 3 is a schematic structural diagram of a second embodiment of a buffer structure of an engine exhaust system according to the present invention.

The reference numbers illustrate:

an exhaust pipe 100, a buffer structure 200, a supercharger 300;

a connecting tube 210, a first tube section 211, transition tube sections 212, 212', a first tube wall portion 2121, a second tube wall portion 2122, a second tube section 213, a first flow passage portion 2101, a second flow passage portion 2102;

the flow guide part 220, the first flow guide section 221, the second flow guide section 222 and the flow guide surface 2221.

Detailed Description

The core of the utility model is to provide an engine exhaust system and buffer structure thereof, this buffer structure locate between exhaust system's blast pipe and the booster, and its structural design can change the gas flow velocity distribution on its export cross-section, reduces the velocity of flow unevenness, reduces the impact that the exhaust caused to the booster.

In order to make the technical field better understand the solution of the present invention, the following detailed description of the present invention is provided with reference to the accompanying drawings and the detailed description.

For ease of understanding and clarity of description, the following description is taken in conjunction with the engine exhaust system and its bumper structure, and the advantageous portions will not be repeated.

Referring to fig. 1 and 2, fig. 1 is a block diagram illustrating an engine exhaust system according to an embodiment of the present invention; fig. 2 is a schematic structural diagram of a first embodiment of a buffer structure of an engine exhaust system according to the present invention.

The exhaust system of the engine comprises an exhaust pipe 100 and a supercharger 300, wherein the exhaust gas of each cylinder flows into the exhaust pipe 100 after being discharged through a corresponding exhaust manifold and then enters the supercharger 300; in order to reduce the impact on the supercharger 300 caused by the difference in the exhaust interval angle between the cylinders, a buffer structure 200 is provided between the outlet of the exhaust pipe 100 and the inlet of the supercharger 300.

The exhaust pipe 100 has two exhaust channels, and the outlet end of the exhaust pipe may be connected to the buffer structure 200 through an exhaust flange of a dual-channel structure.

In this embodiment, the buffering structure 200 includes a connecting pipe 210 and a flow guide 220 disposed in the connecting pipe 210, an inlet end of the connecting pipe 210 is connected to the exhaust pipe 100, and an outlet end is connected to the supercharger 300; the guide 220 is disposed near the inlet section of the connection pipe 210 to divide the inlet section thereof into two flow path portions, i.e., a first flow path portion 2101 and a second flow path portion 2102, which correspond to the two exhaust flow paths of the exhaust pipe 100, respectively, and communicate at the outlet section near the connection pipe 210.

Preferably, in order to make the gas flow in the connecting pipe 210 more uniform, the flow guide member 220 is substantially disposed at the axial position of the connecting pipe 210, that is, the extending direction of the flow guide member 220 is consistent with the axial direction of the connecting pipe 210, so that the flow areas of the two flow channel parts separated by the flow guide member at the same cross section are substantially consistent.

Specifically, the end of the flow guide 220 is flush with the inlet end of the connection pipe 210.

In practical installation, limited by the installation space and structural layout of the engine, the axis of the inlet end of the connecting pipe 210 intersects with the axis of the outlet end of the connecting pipe, that is, the connecting pipe 210 is inclined toward one side as a whole, and accordingly, the flow guide member 220 is also inclined toward the same direction. Regarding the orientation shown in fig. 2, the inlet end of the connecting pipe 210 is the lower end surface of the drawing, in the drawing, the inlet end is parallel to the horizontal plane, the connecting pipe 210 is inclined towards the left side as a whole, and the outlet end is arranged at a certain included angle with the horizontal plane.

As can be seen from fig. 2, the gas in the exhaust pipe 100 flows into the two flow channel portions of the inlet section of the connecting pipe 210 through the two exhaust flow channels, and the gas in the two flow channel portions is merged after flowing through the flow guide 220, and flows out into the supercharger 300 through the outlet end of the connecting pipe 210.

The flow velocity at the outlet end of the connecting pipe 210 on both sides of the flow guide 220 in the cross section is denoted as v1, the flow velocity at the outlet end of the connecting pipe 210 corresponding to the flow guide 220 in the cross section is denoted as v2, and the flow velocity unevenness of the cross section of the outlet end of the connecting pipe 210 is defined as (v1-v2)/v 1.

In this embodiment, the flow guiding member 220 is a plate-shaped structure, and includes a first flow guiding section 221 and a second flow guiding section 222, where the first flow guiding section 221 is perpendicular to the inlet end of the connecting pipe 210, the second flow guiding section 222 is a main structure of the flow guiding member 220 and extends to the transition pipe section 212 of the connecting pipe 210, the second flow guiding section 222 has two opposite flow guiding surfaces 2221, and in the orientation shown in fig. 2, a first flow guiding part 2101 is formed between the flow guiding surface 2221 near the left side and the pipe wall part of the connecting pipe 210 opposite to the first flow guiding surface 2221, and a second flow guiding part 2102 is formed between the flow guiding surface 2221 near the right side and the pipe wall part of the connecting pipe 210.

Along the direction from the inlet of the connecting pipe 210 to the outlet thereof, the thickness of the second flow guiding section 222 is gradually increased and then gradually decreased, so that when the gas entering the runner portion flows along the wall surface of the flow guiding member 220, due to the structural design of the second flow guiding section 222, the gas flow is guided to the middle position of the connecting pipe 210, compared with the existing buffer structure with the flow guiding wall in a linear structure, after the gas flow is converged around the flow guiding member 220 of the present scheme, more gas is deflected to the middle position of the outlet end of the connecting pipe 210, relatively speaking, the flow velocity v2 at the position of the outlet end of the connecting pipe 210 corresponding to the flow guiding member 220 is increased, the difference of the gas flow velocity at the middle position of the outlet end of the connecting pipe 210 close to the pipe wall can be reduced, that is, the difference between the v1 and v2 is also reduced, the unevenness of the flow velocity at the outlet end of the buffer structure, the performance stability and the mechanical reliability of the supercharger 300 are improved, and the performance and the reliability of the engine are further improved.

In a specific embodiment, two opposite guiding surfaces 2221 of the second guiding section 222 are in a curve shape protruding outward, so that the guiding surfaces 2221 are guided more smoothly, and adverse phenomena such as turbulence or vortex are avoided. Here, "outer" refers to a direction away from the center of the connection pipe 210, and outer is referred to hereinafter in accordance with this reference.

Preferably, both the guide surfaces 2221 of the second guide section 222 of the guide member 220 are formed in a parabolic shape, and more specifically, the maximum linear distance at the opening of the parabolic shape of the guide surface 2221 is 10mm to 16 mm.

As shown in fig. 2, more specifically, two opposite guiding surfaces 2221 of the second guiding section 222 are directly intersected at the inner end of the guiding element 220, so that the inner end has a substantially pointed structure, which is beneficial to guide more gas to the middle position of the connecting pipe 210.

In this embodiment, the connection pipe 210 includes a first pipe section 211 connected to the exhaust pipe 100, a second pipe section 213 connected to the supercharger 300, and a transition pipe section 212 'connecting the first pipe section 211 and the second pipe section 213, wherein the transition pipe section 212' is a main structure of the connection pipe 210. As shown in fig. 2, the wall portions of transition section 212' are in a substantially straight configuration,

in the comparative test of the buffer structure 200 provided by this embodiment, the other parameters of the two are similar to each other, and after the flow guide surface of the flow guide member 220 is changed from a straight shape to an outwardly convex parabolic shape, the velocity uniformity on the outlet cross section of the buffer structure 200 is improved.

In the prior art, the air flow velocity at the two sides of the flow guide part is more than 1.22m/s, the air velocity at the middle part is about 0.88m/s, the velocity distribution on the outlet section is obviously uneven, and the velocity unevenness is 27.8%.

In the buffer structure 200 provided in this embodiment, the air flow on both sides of the air guide member 220 is not significantly divided from the air flow in the middle, the air flow velocity on both sides is 1.22m/s, the air flow velocity in the middle is 1.01m/s, and the flow velocity unevenness is 17.2%.

In contrast, the above-mentioned structure of the flow guide member 220 has no great influence on the air flow velocities at the two sides, and mainly increases the middle air flow velocity.

On the basis of the above-mentioned buffering structure 200, the buffering structure 200 may be further improved, specifically referring to fig. 3, fig. 3 is a schematic structural diagram of a second embodiment of the buffering structure of the engine exhaust system according to the present invention.

The same components in this embodiment as those in the first embodiment described above are denoted by the same reference numerals to indicate the relationship and difference therebetween.

In this embodiment, the shape of the flow guiding element 220 of the buffering structure 200 is similar to that of the first embodiment, and the detailed description is omitted, and this embodiment further improves the structure of the connection pipe 210 of the buffering structure 200.

In this embodiment, the connection pipe 210 also includes a first pipe section 211 connected to the exhaust pipe 100, a second pipe section 213 connected to the supercharger 300, and a transition pipe section 212 connecting the two, in this embodiment, the shape and structure of the transition pipe section 212 are mainly modified. Specifically, the wall of the transition pipe section 212 has a curved structure protruding outward so as to guide the gas flowing into the connection pipe 210 to a middle position of the outlet of the connection pipe 210.

After the transition pipe section 212 of the connection pipe 210 is arranged as above, the flow path of the gas flowing into the connection pipe 210 at the connection position of the transition pipe section 212 and the second pipe section 213 is deviated to the middle position of the outlet end of the connection pipe 210 due to the guiding function of the curved pipe wall of the transition pipe section 212 and the guiding function of the guiding surface 2221 of the guiding member 220, and more gas is deviated to the middle position of the outlet end of the connection pipe 210, so that the difference between the flow velocity of the middle position of the section of the outlet end of the connection pipe 210 and the flow velocity of the position close to the peripheral wall can be further reduced, and the unevenness of the flow velocity of the outlet end of the buffer.

In a specific scheme, the wall of the transition pipe section 212 of the connecting pipe 210 is an outward convex elliptical structure, so that the wall surface of the flow channel is guided more smoothly on the basis of changing the gas flow trajectory to enable gas to flow towards the middle of the outlet end, and adverse phenomena such as turbulent flow or vortex flow at the connecting transition position are avoided.

The transition pipe section 212 specifically includes a first pipe wall portion 2121 located at one side of the flow guiding element 220 and a second pipe wall portion 2122 located at the other side of the flow guiding element 220, as described above, because of the objective structural design of the connection pipe 210, in the scheme shown in fig. 3, the length of the first pipe wall portion 2121 close to the left side is smaller than the length of the second pipe wall portion 2122 close to the right side, it can be understood that, because the lengths of the two are different, when the two are set to be in an elliptical structure, the related parameters of the elliptical shape are designed differently, so as to equalize the air flows at the two sides of the flow. Of course, it is understood that the transition section may be symmetrical about an axis if the connection pipe 210 does not need to be offset.

Specifically, the minor axis radius of the elliptical structure of the first tube wall portion 2121 may be selected from a range of 4mm to 7mm, and the minor axis radius of the elliptical structure of the second tube wall portion 2122 may be selected from a range of 6mm to 10 mm.

In practical applications, the specific parameter design of the elliptical structure of the first tube wall portion 2121 and the specific parameter design of the elliptical structure of the second tube wall portion 2122 can be adjusted as required.

It has been found through research that reducing the overall length of the flow guide 220 also facilitates improving the flow uniformity of the outlet cross-section of the buffer structure 200.

As shown in fig. 3, the vertical distance between the inner end of the flow guiding element 220 and the inlet end of the connecting pipe 210 is h1, and the vertical distance between the center point of the outlet end of the connecting pipe 210 and the inlet end of the connecting pipe 210 is h2, and in the specific configuration, the ratio of h1/h2 is selected within the range of 0.5-0.54, so that the flow uniformity of the outlet section of the buffer structure 200 can be effectively improved.

Through experimental study, on the basis of the structural change of the comprehensive connecting pipe 210, the shape change of the flow guide surface 2221 of the flow guide piece 220 and the length change of the flow guide piece 220 relative to the connecting pipe 210, the flow velocity unevenness of the outlet section of the buffer structure 200 can be improved from 27.8% to 8.3%, and the flow velocity distribution uniformity is improved by 70%.

It is right above the utility model provides an engine exhaust system and buffer structure thereof has all carried out detailed introduction. The principles and embodiments of the present invention have been explained herein using specific examples, and the above descriptions of the embodiments are only used to help understand the method and its core ideas of the present invention. It should be noted that, for those skilled in the art, without departing from the principle of the present invention, the present invention can be further modified and modified, and such modifications and modifications also fall within the protection scope of the appended claims.

Claims (6)

1. The buffering structure of the engine exhaust system comprises a connecting pipe and a flow guide piece arranged in the connecting pipe, wherein the flow guide piece is arranged at an inlet section of the connecting pipe so as to divide the inlet section of the connecting pipe into two flow channel parts; its characterized in that, the water conservancy diversion spare is platelike structure, including first water conservancy diversion section and second water conservancy diversion section, the terminal surface of first water conservancy diversion section with the entry end parallel and level of connecting pipe is followed the entry of connecting pipe is to the axis direction of its export, the thickness of second water conservancy diversion section is gradual increase earlier and is convergent again, so that will flow in the gas direction of connecting pipe the middle part position of connecting pipe export.

2. The cushioning structure of claim 1, wherein the two opposing flow-directing surfaces of the second flow-directing section are each convexly curved outwardly.

3. The cushioning structure of claim 2, wherein the two flow guiding surfaces are specifically parabolic in shape.

4. The cushioning structure of claim 3, wherein the maximum linear distance at the opening of the parabolic shape of the flow guide surface is 10mm to 16 mm.

5. The buffer structure of any one of claims 1 to 4, wherein the vertical distance between the inner end of the flow guide and the inlet end of the connecting pipe is h1, the vertical distance between the center point of the outlet end of the connecting pipe and the inlet end of the connecting pipe is h2, and h1/h2 is 0.5-0.54.

6. The engine exhaust system comprises an exhaust pipe, a buffer structure and a supercharger, wherein an outlet of the exhaust pipe is connected with an outlet of the supercharger through the buffer structure; the exhaust pipe is provided with two exhaust flow passages; wherein the buffer structure is according to any one of claims 1 to 5, and the two exhaust flow passages are respectively communicated with the two flow passage portions.

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