CN112145275A

CN112145275A - Novel take limit structure's assembled blast pipe

Info

Publication number: CN112145275A
Application number: CN202011066348.2A
Authority: CN
Inventors: 张敏; 张宏飞; 李继林; 欧阳凤霞; 覃欢欢
Original assignee: Dongfeng Commercial Vehicle Co Ltd
Current assignee: Dongfeng Commercial Vehicle Co Ltd
Priority date: 2020-09-30
Filing date: 2020-09-30
Publication date: 2020-12-29

Abstract

The invention discloses a novel assembled exhaust pipe with a limiting structure. The exhaust pipe comprises an exhaust pipe and a cylinder cover, wherein one or more C-shaped limiting structures are arranged at the joint of the exhaust pipe and the cylinder cover. According to the invention, by adding the limit structure, the flange surface structure of the exhaust pipe is changed, the fastening assembly form is adjusted, the transverse and longitudinal displacement of the engine exhaust pipe is released as far as possible on the premise of ensuring the system rigidity, the high stress and high strain which are generated by the exhaust pipe and cannot be released due to thermal expansion are reduced, the low-cycle fatigue failure is reduced, and the low-cycle fatigue life is prolonged.

Description

Novel take limit structure's assembled blast pipe

Technical Field

The invention belongs to the technical field of diesel engine exhaust systems, and particularly relates to a novel assembled exhaust pipe with a limiting structure.

Background

The exhaust pipe is used as an important part in the field of diesel engine design, is in extremely severe working environment and is used as a bearing part to bear impact load caused by impact of a supercharger system, an air inlet and exhaust pipeline and the like; the sealing pressure-bearing piece is used for bearing pressure load brought by gas pressure, and the sealing property of the whole system is ensured; the risk of low-cycle fatigue failure brought by a high-temperature working environment is borne; as a bearing part and a sealing pressure-bearing part, the exhaust system has enough rigidity and the structure is as compact and rigid as possible; however, in order to prevent the exhaust pipe from having a wider range of low cycle fatigue failure, it is necessary to make the exhaust pipe relatively simple in structure and more flexible so as to release the thermal stress caused by high temperature. This is a pair of design concepts that interact and contradict each other, and the balance point needs to be found.

At present, the fastening installation of a main stream exhaust pipe mainly comprises a bolt, a spacer bush, an exhaust pipe, a gasket, a cylinder cover and other components. The fastening bolt often has the phenomenon that the axial force is attenuated due to high temperature and vibration, so that the sealing fails, and therefore, the modes of reducing the temperature, increasing the axial force of the bolt or increasing the number of the bolts and the like are adopted at the present stage; the sealing problem is solved based on cooling and increasing the rigidity of the system, but great risks are brought, the large-rigidity system reduces the capability of the system for releasing thermal expansion, high strain is generated along with the capability, and the fatigue failure risk is great. At present, the test bed and the large-range exhaust pipe failure cases in the market are analyzed, and the root cause of the large-range exhaust pipe failure cases is low-cycle fatigue failure caused by high temperature.

In the same way as in the new patent CN203796387U, an exhaust pipe of an internal combustion engine is provided, but a certain amount of bending forms must be generated based on the arrangement form, so that the structure has certain elasticity, and the following disadvantages are: the assembly, the universality and the feasibility are poor; the second disadvantage is that: the limited amount of deformation that can be released by the structure of the exhaust pipe itself is not sufficient to fundamentally eliminate the thermal stress of the exhaust pipe due to thermal expansion.

For another example, patent CN111188678A relates to a balanced exhaust branch pipe assembly for a single cylinder diesel engine, which uses a dual bellows flexible structure to compensate for the thermal expansion of the exhaust pipe; the double-bellows structure is adopted, so that the cost is higher; the system rigidity is reduced, and the corrugated pipe is easy to generate fatigue damage; the technology is applied to the single-cylinder testing machine technology, and the application of the whole machine is difficult.

Therefore, it is necessary to design a novel assembled exhaust pipe which can be assembled at low cost, has strong universality and lower cost, and can fundamentally solve the problem of low-cycle fatigue caused by the fact that thermal expansion cannot be released.

Disclosure of Invention

The invention aims to solve the defects in the prior art and provide a novel assembled exhaust pipe with a limiting structure. The thermal expansion of the exhaust system caused by the high-temperature working environment is released as much as possible, and the risk of low-cycle fatigue failure is reduced.

The technical scheme adopted by the invention is as follows: the utility model provides a novel take limit structure's assembled blast pipe, includes blast pipe and cylinder cap, the blast pipe is equipped with one or more C type limit structure with the cylinder cap junction.

In a further preferable structure, the cylinder cover and the exhaust pipe are fixedly connected through a bolt and a C-shaped limiting structure.

In a further preferred structure, the C-shaped limiting structure is C-shaped or U-shaped.

The structure enables the system to be relatively more elastic and can release larger deformation; the limiting structure is simple in structure and convenient to process, the control flatness is convenient to install, and the strength of the limiting structure is ensured by the large transition fillet; the heat-resistant coating can be sprayed on the mounting surface of the exhaust pipe, so that the temperature is further reduced.

The C-shaped limiting structure is made of high-strength materials, rigidity and strength of the C-shaped limiting structure are guaranteed, and the thermal expansion coefficient of the C-shaped limiting structure is smaller than that of the exhaust pipe body.

In a further preferred structure, the bottom of the exhaust pipe is connected with an exhaust flange, and the C-shaped limiting structure is positioned on the upper end face of the exhaust flange and is fastened and connected through bolts.

The structure of further preferred, C type limit structure includes spacing face in upper end and the spacing face of lower extreme, be equipped with the opening between spacing face in upper end and the spacing face of lower extreme, connect through vertical connecting portion between spacing face in upper end and the spacing face of lower extreme.

In a further preferred structure, the centers of the upper end limiting surface and the lower end limiting surface are provided with coaxial mounting through holes.

In a further preferable structure, the plurality of C-shaped limiting structures are symmetrically arranged on the upper end face of the exhaust flange, and the openings face the inner side.

In a further preferable structure, the C-shaped limiting structure and the exhaust pipe are in transition fit in the axial force direction of the bolt. The installation is convenient; because the limiting structure is not in direct contact with the exhaust gas, the temperature is relatively low, so that the thermal expansion of the whole limiting structure is smaller than that of the flange surface of the exhaust pipe; under the operating condition, make limit structure and flange face tightly laminate through the different thermal expansion volume between the part, guaranteed the rigidity of entire system promptly, through the limit structure release part bolt axial force displacement in the direction again of structure, promote low cycle fatigue resistance ability.

In a further preferred construction, the bolt is clearance fitted to the exhaust pipe. The form is equal to an air spacer bush, so that the temperature of the bolt can be reduced, and the risk of axial force attenuation of the bolt is reduced.

In a further preferable structure, the exhaust pipe fastening mounting hole and the C-shaped limiting structure are in clearance fit with a bolt rod body of the bolt. The exhaust pipe body can freely move in the fastening and combining surface (relatively directly fastened by bolts), so that larger thermal expansion amount can be released, and the low-cycle fatigue life is prolonged.

The invention has the beneficial effects that: through increasing limit structure, change blast pipe flange face structure, the adjustment fastening assembly form is under the prerequisite of guaranteeing system rigidity, releases engine exhaust pipe horizontal and fore-and-aft displacement as far as possible, reduces its high stress, the high strain that can't release the production by the thermal expansion, reduces low cycle fatigue failure, promotes low cycle fatigue life.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a side view of the present invention;

FIG. 3 is a cross-sectional view taken along line A-A of FIG. 1;

FIG. 4 is a schematic structural view of a C-shaped limiting structure;

the exhaust pipe structure comprises a cylinder cover 1, an exhaust pipe 2, an exhaust pipe flange 2, a bolt 3 and a 4-C-shaped limiting structure 4-1, an upper end limiting surface 4-2, an opening 4-3, a lower end limiting surface 4-4, a vertical connecting part 4-4 and a mounting through hole 4-5.

Detailed Description

The invention will be further described in detail with reference to the following drawings and specific examples, which are not intended to limit the invention, but are for clear understanding.

As shown in fig. 1-3, the design and assembly of the whole system: the cylinder cover 1 and the exhaust pipe 2 are tightly connected by bolts 3 and a C-shaped limiting structure 4. The A-A assembly cross-sectional view shows the assembly process between the components.

FIG. 4 is a schematic structural diagram of a C-shaped limiting structure (the arrangement of the C-shaped limiting structure can be properly adjusted according to the requirements of the assembly space of the whole machine, etc.), and the strength of the C-shaped limiting structure is ensured by sufficient strength and flatness and a large round angle; the C-shaped limiting structure 4 comprises an upper limiting surface 4-1 and a lower limiting surface 4-3, an opening 4-2 is arranged between the upper limiting surface 4-1 and the lower limiting surface 4-3, the upper limiting surface 4-1 and the lower limiting surface 4-3 are connected through a vertical connecting part 4-4, and a coaxial mounting through hole 4-5 is formed in the centers of the upper limiting surface and the lower limiting surface. The mounting through hole is oval, so that a large enough deformation space can be ensured in the axial direction of the exhaust pipe, larger strain is released, and the risk of low-cycle fatigue damage is reduced.

The C-shaped limiting structure 4 and the exhaust pipe flange 2-1 are in transition fit, and when the engine is in a cold state, the whole exhaust system can be well fixed after the bolt 3 is tightened due to the high elasticity and the strength of the C-shaped limiting structure 4.

The C-shaped limiting structure is not in direct contact with exhaust gas, and the temperature is relatively low, so that the thermal expansion of the whole limiting structure is smaller than that of the flange surface of the exhaust pipe; when the anti-fatigue structure is in a working state (thermal state), the C-shaped limiting structure is tightly attached to the flange face through different thermal expansion amounts among the components, so that the rigidity of the whole system is ensured, and the displacement in the axial force direction of a part of bolts is released through the C-shaped limiting structure of the structure, so that the low-cycle fatigue resistance is improved.

The C-shaped limiting structure 4 is equivalent to an air spacer bush, so that the temperature of the bolt 3 is lower, and the risk of axial force attenuation is reduced.

Under operating condition, the exhaust pipe 2 slides relatively freely in the C-shaped limiting structure 4, and is freely deformed, so that the thermal strain is greatly reduced, and the service life of the low cycle is prolonged.

Those not described in detail in this specification are within the skill of the art.

Claims

1. The utility model provides a novel take limit structure's assembled blast pipe, includes blast pipe and cylinder cap, its characterized in that: one or more C-shaped limiting structures are arranged at the joint of the exhaust pipe and the cylinder cover.

2. The novel assembled exhaust pipe with the limiting structure according to claim 1, wherein: the cylinder cover and the exhaust pipe are connected with each other through bolts and C-shaped limiting structures in a fastening mode.

3. The novel assembled exhaust pipe with the limiting structure according to claim 1, wherein: the C-shaped limiting structure is C-shaped or U-shaped.

4. The exhaust pipe with the limit structure as claimed in claim 1 or 2, wherein: the bottom of the exhaust pipe is connected with an exhaust flange, and the C-shaped limiting structure is positioned on the upper end face of the exhaust flange and is fastened and connected through bolts.

5. The novel assembled exhaust pipe with the limiting structure according to claim 1, wherein: the C-shaped limiting structure comprises an upper end limiting face and a lower end limiting face, an opening is formed between the upper end limiting face and the lower end limiting face, and the upper end limiting face and the lower end limiting face are connected through a vertical connecting part.

6. The novel assembled exhaust pipe with the limiting structure according to claim 5, wherein: and the centers of the upper end limiting surface and the lower end limiting surface are provided with coaxial mounting through holes.

7. The novel assembled exhaust pipe with the limiting structure according to claim 4, wherein: a plurality of C type limit structure symmetrical arrangement on exhaust flange up end, and the opening is inboard towards.

8. The novel assembled exhaust pipe with the limiting structure according to claim 2, wherein: the C-shaped limiting structure and the exhaust pipe are in transition fit in the axial force direction of the bolt.

9. The novel assembled exhaust pipe with the limiting structure according to claim 2, wherein: the bolt is in clearance fit with the exhaust pipe.

10. The novel assembled exhaust pipe with the limiting structure according to claim 2, wherein: the exhaust pipe fastening mounting hole and the C-shaped limiting structure are in clearance fit with a bolt rod body of the bolt.