CN110939737A

CN110939737A - Expanded graphite sealing device with anti-shearing function

Info

Publication number: CN110939737A
Application number: CN201911234980.0A
Authority: CN
Inventors: 赵亚飞; 潘代锋; 李贵林; 贺耀; 李炎军; 孙珊; 任是旋
Original assignee: AECC Sichuan Gas Turbine Research Institute
Current assignee: AECC Sichuan Gas Turbine Research Institute
Priority date: 2019-12-05
Filing date: 2019-12-05
Publication date: 2020-03-31

Abstract

The invention provides an expanded graphite sealing device with a shear-proof function, which comprises a bearing cavity shell, an expanded graphite sealing ring, an anti-rotation pressure ring, an oil supply pipe and a compression nut, wherein the bearing cavity shell is provided with a bearing cavity; the oil supply pipe penetrates through the graphite sealing ring and the central hole of the anti-rotation pressure ring and is inserted into the bearing cavity shell; the compression nut is matched with the thread of the bearing cavity shell to compress the expanded graphite sealing ring and the anti-rotation compression ring between the compression nut and the bearing cavity shell. The sealing device provided by the invention effectively avoids the defects of the original sealing structure, and has the advantages of small occupied space, simple structure and process, high processing speed, low cost, convenience in assembly and disassembly, high reliability and high sealing performance. The defects of low reliability, large occupied space, high assembly rejection rate, poor sealing and pressing test effect after assembly and the like of other sealing structures are overcome. The reliability of the sealing structure after assembly is improved, and the cost is effectively saved.

Description

Expanded graphite sealing device with anti-shearing function

Technical Field

The invention belongs to the field of design of aero-engines, and relates to an expanded graphite sealing device with a shear-resistant function

Background

In the current aeroengine bearing cavity, when lubricating oil enters the bearing cavity through an oil supply pipe on the bearing cavity shell and supplies lubricating oil to the bearing, the rubber sealing ring is not suitable for use under the high-temperature condition that the external environment temperature of the bearing cavity is more than 300 ℃. The expanded graphite is generally used for sealing between the bearing cavity shell and the oil supply pipe, and the principle is that the expanded graphite is subjected to axial pressing force of a compression nut to generate radial expansion so as to be attached to a pipeline for sealing.

However, in order to ensure the sealing performance, in the installation process of the sealing structure, a large tightening torque is usually applied to the compression nut to obtain a large pressure, so that the sealing ring is deformed; since the compression nut needs to compress the expanded graphite while rotating, the expanded graphite is subjected to a large circumferential shearing force from the nut, and the sealing surface of the expanded graphite sealing ring is easily cut to cause sealing failure. Based on the reasons, when the traditional expanded graphite sealing structure is used for carrying out a bearing cavity lubricating oil leakage detection test, lubricating oil leakage often occurs, and a better sealing test result can be obtained accidentally only after the leakage detection test is carried out for more than ten times by repeatedly replacing the graphite ring. This current situation seriously affects the reliability of the seal structure, wastes a large number of qualified seal ring parts and seriously reduces the assembly efficiency of the engine.

Disclosure of Invention

The purpose of the invention is as follows: in order to solve the technical problems, the invention designs a novel sealing structure of the oil way of the bearing cavity, wherein the anti-rotation compression ring is added, so that the sealing surface of the sealing element can be effectively prevented from being damaged, and the damage and the failure of the sealing ring caused by assembly are obviously reduced; meanwhile, the times of repeated disassembly and assembly are reduced, and the purposes of improving the sealing reliability, saving the economic cost and improving the assembly efficiency are finally achieved.

Technical scheme

The invention provides an expanded graphite sealing device with a shear-proof function, which comprises a bearing cavity shell, an expanded graphite sealing ring, an anti-rotation pressure ring, an oil supply pipe and a compression nut, wherein the bearing cavity shell is provided with a bearing cavity; the oil supply pipe penetrates through the graphite sealing ring and the anti-rotation pressure ring and is inserted into the bearing cavity shell; the compression nut is matched with the thread of the bearing cavity shell to compress the expanded graphite sealing ring and the anti-rotation compression ring between the compression nut and the bearing cavity shell. The function of axially pressing and deforming the expanded graphite sealing ring is achieved. Before the gland nut is screwed down, a radial gap exists between the oil supply pipe and the expanded graphite sealing ring, and after the gland nut is screwed down, the expanded graphite sealing ring expands and deforms in the radial direction and then generates a sealing effect after being connected with the oil supply pipe.

Furthermore, the outer surface of the bearing cavity shell is provided with a cylindrical bulge, and a threaded hole is formed in the bulge; and an anti-rotation groove is formed in the circumferential direction of an inner cylindrical binding surface in contact with the expanded graphite sealing ring, and the sealed binding bottom surface of the bearing cavity shell is subjected to silver plating treatment and grinding.

The threaded holes are formed in the cylindrical protrusions on the outer surface, so that the strength can meet the requirement, and meanwhile, the occupied space and the weight of the bearing cavity shell are reduced to the maximum extent.

Furthermore, four edges of the expanded graphite sealing ring are wrapped with metal wrapping edges.

The expanded graphite sealing ring is made of a common expanded graphite material, the metal wrapping edges are made of a high-temperature alloy material, the conditions that the four edges of the expanded graphite sealing ring are subjected to block falling, impact and the like are prevented, and meanwhile the anti-shearing capacity of the expanded graphite sealing ring at the weak edges is enhanced.

Furthermore, clearance fit is carried out between the expanded graphite sealing ring and the oil supply pipe in a free state, when pressure is applied to the upper sealing end face of the expanded graphite sealing ring, the size of the expanded graphite sealing ring in the vertical direction is increased to generate a convex hull, and the convex hull enables the expanded graphite sealing ring to be tightly attached to the oil supply pipe.

Furthermore, the anti-rotation pressure ring circumferentially extends out of the uniformly distributed anti-rotation lugs in the circumferential direction, and the anti-rotation lugs are matched with the bearing cavity shell; and the binding surface of the anti-rotation pressure ring, which is bound with the expanded graphite sealing ring, and the compression surface bound with the nut are plated with silver.

The anti-rotation compression ring has the effects that the section pressing force of the compression nut is uniformly transmitted to the expanded graphite sealing ring, and the anti-rotation lug has the effect of preventing the compression nut from driving the anti-rotation compression ring to rotate due to friction force when rotating; silver plating can prevent parts from being bonded at high temperature and has a lubricating effect in the micromotion process in the vibration process of an engine. A gap convenient to install is formed between the anti-rotation lug of the anti-rotation pressure ring and the anti-rotation groove of the bearing cavity shell, and when the compression nut is screwed, the anti-rotation groove and the anti-rotation lug of the anti-rotation pressure ring are matched with each other to offset shearing force generated aiming at the anti-rotation pressure ring.

Furthermore, the oil supply pipe is a thin-wall pipe fitting, and one end of the oil supply pipe entering the bearing cavity shell is provided with a guide spray hole.

The function of the guide spray hole is not limited to oil supply, and can also be applied to the functions of oil pumping, gas supply, exhaust and the like.

Furthermore, the end of the compression nut is a hexagonal square head; the middle section of the cylindrical surface of the inner hole of the nut is expanded in the radial direction, and an anti-scraping molded surface is arranged in the hole; and nitriding the bottom surface of the nut.

The purpose of the scratch-resistant profile is to reduce the contact area with other parts and thus to make insertion and removal of the supply line smoother. The nitriding treatment is carried out on the bottom surface of the nut so as to ensure higher hardness and roughness of the bottom of the nut.

The invention can effectively prevent the lubricating oil in the bearing cavity from leaking under the high-temperature condition, and can also prevent external hot air from entering the bearing cavity to play a role in protecting the bearing cavity. The invention can be used for the parts of the bearing cavity oil supply pipeline needing to be connected, penetrated and embedded into other components under the high-temperature environmental condition in the engine. The invention can be used for sealing the oil supply pipe entering the bearing cavity, and can also be used for sealing liquid working medium pipelines such as an oil return pipeline and a fuel pipeline of the bearing cavity of an aeroengine when the liquid working medium pipelines penetrate into the cavity shell, thereby having wide application prospect.

Advantageous effects

1. The sealing device provided by the invention is provided with the anti-rotation structure, the sealing ring cannot be cut to be broken, and the sealing reliability is high after the sealing device is assembled.

2. The sealing device provided by the invention adopts a single nut structure concentric with the oil supply pipe, so that the sealing device is more space-saving in structure and convenient to assemble and disassemble.

3. The sealing device provided by the invention has the advantages that silver plating and grinding treatment are carried out on the sealing surface, and metal edge covering treatment is carried out on the edge, so that excellent sealing performance is obtained.

4. The sealing device provided by the invention effectively avoids the defects of the original sealing structure, and has the advantages of small occupied space, simple structure and process, high processing speed, low cost, convenience in assembly and disassembly, high reliability and high sealing performance. The defects of low reliability, large occupied space, high assembly rejection rate, poor sealing and pressing test effect after assembly and the like of other sealing structures are overcome. The reliability of the sealing structure after assembly is improved, and the cost is effectively saved.

Drawings

Fig. 1 is a schematic structural view of an expanded graphite sealing device having a shear prevention function according to the present invention.

Fig. 2 is a schematic structural view of a bearing cavity housing.

Fig. 2a) is a two-dimensional view of a bearing cavity housing.

Fig. 2b) is a three-dimensional view of the bearing chamber housing.

FIG. 3 is a schematic view of the structure of an expanded graphite seal ring.

FIG. 3a) is a two-dimensional view of an expanded graphite sealing ring.

FIG. 3b) is a three-dimensional view of the expanded graphite sealing ring.

Figure 4 is a schematic representation of radial deformation of the expanded graphite seal ring.

Fig. 5 is a schematic view of the anti-rotation ring.

Fig. 5a) is a two-dimensional view of the anti-rotation ring.

Fig. 5b) is a three-dimensional view of the anti-rotation ring.

Fig. 6 is a schematic view of the structure of the oil supply pipe.

Fig. 6a) is a two-dimensional view of the oil supply pipe.

Fig. 6b) is a three-dimensional view of the oil supply pipe.

Fig. 7 is a schematic view of the construction of the compression nut.

Fig. 7a) is a two-dimensional view of the compression nut.

Fig. 7b) is a three-dimensional view of the compression nut.

Fig. 8 is an assembly view of an expanded graphite sealing apparatus having a shear prevention function according to the present invention. The bearing comprises a bearing cavity shell, an expanded graphite sealing ring, an anti-rotation compression ring and a compression nut, wherein the bearing cavity shell is 1, the expanded graphite sealing ring is 2, the anti-rotation compression ring is 3, and the compression nut is 4. 5-oil supply pipe, 6-threaded hole, 7-inner cylindrical wall surface, 8-sealing joint bottom surface, 9-anti-rotation groove, 10-metal edge covering, 11-upper sealing end surface, 12-convex hull, 13-anti-rotation lug, 14-sealing joint top surface, 15-compression surface, 16-guide spray hole, 17-hexagonal square head, 18-anti-scraping molded surface and 19-nut bottom surface.

Detailed Description

The invention will be further explained with reference to the drawings

Fig. 1 is a schematic structural view of an expanded graphite sealing device with a shear prevention function according to the present invention. The sealing device consists of a bearing cavity shell (1), an expanded graphite sealing ring (2), an anti-rotation pressure ring (3), an oil supply pipe (4) and a compression nut (5). Firstly, an oil supply pipe (4) penetrates through the graphite sealing ring (2) and the anti-rotation pressing ring (3) to be inserted into the bearing cavity shell (1). At this time, a radial gap is formed between the oil supply pipe (4) and the expanded graphite seal ring (2). After the compression nut (5) is screwed into the bearing cavity shell (1) through threads, the expanded graphite sealing ring (2) and the anti-rotation pressing ring (3) are compressed between the bearing cavity shell (1) and the compression nut (5), and the compression nut (5) is screwed up to axially compress the expanded graphite sealing ring (2) to be compressed and deformed. The expanded graphite sealing ring (2) is subjected to radial expansion deformation after being pressed, and the inner cylindrical surface of the expanded graphite sealing ring (2) is attached to the outer cylindrical surface of the oil supply pipe (4) to generate a sealing effect.

As shown in figure 2, the bearing cavity shell (1) is provided with a cylindrical bulge extending out of the outer surface, a threaded hole (6) is formed in the bulge, and the wall surface of the threaded hole (6) is 5mm thick, so that the occupied space and the weight of the bearing cavity shell (1) can be reduced to the maximum extent while sealing is realized. The bearing cavity shell (1) is provided with uniformly distributed anti-rotation grooves (9)2 in the circumferential direction of an inner cylindrical binding surface (7) which is in contact with the expanded graphite sealing ring (2). The seal-bonded bottom surface (8) needs to be bonded to the expanded graphite seal ring (2), and therefore the seal-bonded bottom surface (8) is polished by silver plating to increase the surface roughness to 0.1 μm, which is the upper limit of Ra.

As shown in fig. 3, it is a schematic structural diagram of the expanded graphite sealing ring (2), and its material is a common expanded graphite material; the four edges of the expanded graphite sealing ring (2) are wrapped with metal wrapping edges (10) made of high-temperature alloy materials, so that the conditions that the four edges of the expanded graphite sealing ring are subjected to chipping and bruising and the like are prevented, and the shearing resistance of the expanded graphite sealing ring (2) at the weak edges is enhanced.

As shown in FIG. 4, it is a schematic view showing the radial deformation of the expanded graphite seal ring (2). For clearance fit under free state between expanded graphite sealing ring (2) and oil feed pipe (4), when pressure was applied to expanded graphite sealing ring (5) top seal terminal surface (11), the expanded graphite sealing ring can produce and warp, and along the reduction of pressure direction size, because of the size increase of the perpendicular pressure direction of pressurized inflation and then produce convex closure (12), thereby convex closure (12) make expanded graphite sealing ring (2) and oil feed pipe (4) closely laminate and play the sealed effect to the bearing chamber.

As shown in fig. 5, the anti-rotation ring (3) in the sealing structure is used for uniformly transmitting the end face pressing force of the compression nut (4) to the expanded graphite sealing ring (2). Prevent changeing clamping ring (3) circumference and stretch out circumferencial direction width of two equipartitions and be 4mm prevent changeing lug (13), its effect prevents that gland nut (5) from rotating time owing to frictional force drives prevents changeing clamping ring (3) and rotates, prevents changeing clamping ring (3) axial thickness and is 7mm, prevents changeing the axial thickness of lug (13) and is 4.5 mm. Silver plating is carried out on the sealing and attaching top surface (14) and the pressure-receiving surface (15), so that parts can be prevented from being bonded at high temperature, and the lubricating effect is achieved in the micro-motion process in the vibration process of an engine. The surface roughness of the seal-bonding top surface (14) is 0.1 [ mu ] m which is the upper limit value of Ra, so as to improve the reliability of sealing. A gap of 0.1mm is reserved between an anti-rotation lug (13) of the anti-rotation pressing ring (3) and an anti-rotation groove (8) of the bearing cavity shell (1), so that the mounting and the dismounting are convenient. When the compression nut (5) is screwed, the anti-rotation groove (9) and the anti-rotation lug (13) of the anti-rotation pressing ring (3) are matched with each other, so that shearing force applied to the anti-rotation pressing ring (3) when the compression nut (5) is screwed in can be offset.

As shown in fig. 6, it is an oil supply pipe (4) in the sealing structure, which is a thin-walled pipe member, with a total length greater than 100mm and a wall thickness of 3.5mm, and a guide spray hole (16) is opened at one end entering the bearing cavity housing (1) for supplying oil to friction heating parts such as bearings.

As shown in fig. 7, the compression nut (5) in the sealing structure is provided, and the end of the compression nut (5) is a hexagonal square head (17) for facilitating the disassembly of the wrench. When processing, the middle section of the inner hole cylindrical surface is reamed towards the outer side of the radial direction, the anti-scraping molded surface (18) is turned out by a lathe, and the purpose of the anti-scraping molded surface (18) is to reduce the contact area with the oil supply pipe (4), so that the oil supply pipe (4) can be sleeved and detached more smoothly. The bottom surface (19) of the nut requires high hardness and roughness, so that the bottom surface (19) of the nut is nitrided after the completion of machining, and the upper limit Ra of the bottom surface is 0.1 μm by grinding after nitriding.

Fig. 8 is an assembly view showing a sealing structure of an oil supply line in a high temperature environment according to the present invention. The method comprises the following steps of firstly, carrying out necessary cleaning on a bearing cavity shell (1), secondly, placing an expanded graphite sealing ring (2), thirdly, placing an anti-rotation pressing ring (3), fourthly, inserting an oil supply pipe (4), and fifthly, screwing a compression nut (5).

The invention can effectively prevent the lubricating oil in the bearing cavity from leaking under the high-temperature condition, and can also prevent external hot air from entering the bearing cavity to play a role in protecting the bearing cavity. The invention can be used for sealing the joint part of other components which need to be penetrated and embedded by the oil supply pipeline of the bearing cavity under the condition of high-temperature environment in the engine. The invention can also be used for sealing the joint parts of the oil return pipeline of the bearing cavity, fuel oil, air entraining pipeline and ventilation pipeline which need to penetrate and be embedded into other components and parts under the condition of high temperature environment in the engine, and has wide application prospect.

Claims

1. An expanded graphite sealing device with a shear-proof function is characterized by comprising a bearing cavity shell, an expanded graphite sealing ring, an anti-rotation pressure ring, an oil supply pipe and a compression nut; the oil supply pipe penetrates through the graphite sealing ring and the central hole of the anti-rotation pressure ring and is inserted into the bearing cavity shell; the compression nut is matched with the thread of the bearing cavity shell to compress the expanded graphite sealing ring and the anti-rotation compression ring between the compression nut and the bearing cavity shell.

2. The seal arrangement of claim 1, wherein the outer surface of the bearing cavity housing is provided with a cylindrical protrusion having a threaded bore therein; and an anti-rotation groove is formed in the circumferential direction of an inner cylindrical binding surface in contact with the expanded graphite sealing ring, and the sealed binding bottom surface of the bearing cavity shell is subjected to silver plating treatment and grinding.

3. The seal of claim 1, wherein the expanded graphite seal ring is wrapped with a metal border at each of the four edges.

4. The seal of claim 3, wherein the seal ring is in free clearance fit with the oil supply pipe, and wherein when pressure is applied to the upper seal surface of the seal ring, the seal ring increases in vertical dimension to create a convex hull that causes the seal ring to closely engage the oil supply pipe.

5. The sealing device according to claim 1, wherein the anti-rotation pressure ring circumferentially extends out of evenly distributed anti-rotation lugs in the circumferential direction, and the anti-rotation lugs are matched with the bearing cavity shell; and the binding surface of the anti-rotation pressure ring, which is bound with the expanded graphite sealing ring, and the compression surface bound with the nut are plated with silver.

6. The seal of claim 1 wherein said oil supply tube is a thin walled tube having pilot holes at one end into the bearing cavity housing.

7. The sealing device of claim 1, wherein the compression nut has a hexagonal square end at the end thereof; reaming the middle section of the inner hole cylindrical surface of the nut in the radial direction; and an anti-scraping molded surface is arranged in the hole, and the bottom surface of the nut is subjected to nitriding treatment.