A self-forced cooling high temperature resistant mechanical sealing device

Abstract

The present invention relates to a self-forced cooling high temperature resistant mechanical sealing device, wherein the dynamic ring, static ring seat and heat insulating ring of the sealing device are all mounted on a rotating shaft; a guide groove is arranged on the dynamic ring; an annular shell is mounted on the heat insulating ring and the static ring seat, and one side of the annular shell is fixedly sealed with the heat insulating ring, the inner wall of the other side of the annular shell and the outer circular surface of the static ring seat form an annular inlet for liquid medium, an annular diaphragm group is mounted on the heat insulating ring and has a gap with the outer ring wall of the heat insulating ring, and the outer edges of both sides of the annular diaphragm group are fully welded with the static ring seat and the heat insulating ring in the circumferential direction; thus, a cavity is formed between the annular shell and the annular diaphragm group; a small hole connected to the cavity is arranged on the outer wall of the annular shell; the liquid medium annular inlet, the cavity and the small hole form a cooling channel. The arrangement of the guide groove and the cooling channel causes the liquid medium to vaporize, resulting in unstable operation of the mechanical seal, leakage of the sealing surface and even sealing failure.

Description

Technical Field

[0001] The invention relates to the technical field of sealing, and in particular to a self-forced cooling high-temperature resistant mechanical sealing device. Background Art

[0002] In the prior art, the turbopump assembly is the core component of the liquid rocket engine propellant supply system, which mainly realizes the pressurization of the incoming flow medium and delivers the propellant to the combustion chamber according to the designed flow rate and pressure. Usually, a set of mechanical sealing devices is arranged on the rotating shaft between the pump inlet and the turbine in the liquid rocket engine turbopump, in order to achieve a small amount of propellant medium or no propellant leakage into the turbine chamber.

[0003] When the existing mechanical seal device is working, the maximum PV value is close to 60MPa.m / s, which will cause the following problems:

[0004] 1. The temperature of the end surface of the mechanical seal friction pair rises rapidly, and the friction pair exhibits dry grinding, thermal cracking, deformation and other phenomena.

[0005] 2. The temperature of the turbine chamber is as high as 650-800℃. The existing mechanical seal device has no auxiliary cooling function and can only rely on its own ability to dissipate heat. The liquid medium around the friction pair will vaporize, causing the mechanical seal to work unstable, the sealing surface to leak, and even the sealing failure. Summary of the invention

[0006] In order to solve the problems in the background technology, the present invention provides a self-forced cooling high temperature resistant mechanical sealing device with good sealing performance and simple structure in a high temperature environment.

[0007] The technical solution of the present invention is:

[0008] The present invention provides a self-forced cooling high temperature resistant mechanical sealing device, comprising an O-type rubber ring, a dynamic ring, a graphite ring, a static ring seat, an annular diaphragm group, an annular housing and a heat insulation ring;

[0009] The moving ring is fixedly mounted on the end of the rotating shaft close to the pump inlet, and an O-type rubber ring is installed between the inner ring wall of the moving ring and the outer surface of the rotating shaft. The stationary ring seat is mounted on the end of the rotating shaft away from the pump inlet. A graphite ring is arranged between the moving ring and the stationary ring seat, one end face of the graphite ring contacts the moving ring, and the other end face of the graphite ring is in clearance fit with the stationary ring seat.

[0010] The thermal insulation ring is sleeved on the end of the rotating shaft away from the pump inlet and is located behind the stationary ring seat; the annular shell is sleeved on the thermal insulation ring and the stationary ring seat, and one side of the annular shell is fixedly sealed with the thermal insulation ring, and the inner wall of the other side of the annular shell and the outer circular surface of the stationary ring seat form an annular inlet for liquid medium, the annular diaphragm group is sleeved on the thermal insulation ring and has a gap with the outer ring wall of the thermal insulation ring, and the outer edges of both sides of the annular diaphragm group are fully welded to the stationary ring seat and the thermal insulation ring in the circumferential direction; thereby, a cavity is formed between the annular shell and the annular diaphragm group; at least two small holes connected to the cavity are evenly arranged on the outer wall of the annular shell in the circumferential direction; the liquid medium annular inlet, the cavity and the small holes form a cooling channel.

[0011] Furthermore, in order to prevent the liquid medium around the dynamic ring from vaporizing due to high temperature, a plurality of guide grooves are provided on the outer circumferential surface of the dynamic ring along the circumferential direction.

[0012] Furthermore, the angle between the guide groove and the flow direction of the liquid medium is α°, 25°<α°<45°.

[0013] Furthermore, in order to effectively eliminate the influence of shaft system fluctuations on the sealing performance of the dynamic ring and to have good floating performance, and at the same time to ensure that the heat dissipation capacity of the mechanical dynamic ring guide groove is the same when the shaft rotates clockwise and counterclockwise, the dynamic ring needs to be disassembled and assembled. The dynamic ring is a split structure, including a ring body and a bushing; the bushing includes a circular ring and an annular protrusion arranged on the end face of the circular ring, and the ring body is mounted on the annular protrusion; an O-type rubber ring is also arranged between the ring body and the annular protrusion; the end face of the ring body is gap-fitted with the end face of the circular ring; the guide groove is arranged on the outer circular surface of the ring body.

[0014] Furthermore, in order to prevent the ring body and the circular ring from rotating relative to each other, a first anti-rotation groove is provided on the end surface of the ring body and the circular ring where the gap fits, and a first anti-rotation ear matched with the first anti-rotation groove is provided on the circular ring.

[0015] Furthermore, in order to prevent the stationary ring seat and the annular shell from rotating relative to each other, a second anti-rotation ear is provided on the outer circumferential surface of the stationary ring seat; and a second anti-rotation groove matched with the second anti-rotation ear is provided on the inner wall of the annular shell.

[0016] Furthermore, the annular diaphragm group is welded in sequence from left to right along the axial direction of the rotating shaft by N annular plates; the specific welding method is: the right outer edge of the inner hole of the first annular plate is welded to the left outer edge of the inner hole of the second annular plate, and the right outer edge of the outer circular surface of the second annular plate is welded to the left outer edge of the outer circular surface of the third annular plate, and this rule is followed until N annular plates are welded; N≥10.

[0017] Furthermore, the cross section of the annular sheet is wavy.

[0018] Furthermore, an annular boss is provided on the end surface of the stationary ring seat that contacts the graphite ring, and the inner surface of the annular boss is tightly fitted with the outer circular surface of the graphite ring; and a stress release annular groove is provided on the inner surface of the annular boss.

[0019] Furthermore, the gap between the end face of the graphite ring and the stationary ring seat is ≤0.03mm, the gap between the annular diaphragm group and the outer ring wall of the insulation ring is ≤5mm; the depth of the guide groove is 0.5-1.5mm, and the width of the guide groove is 3-5mm.

[0020] The beneficial effects of the present invention are:

[0021] 1. The mechanical seal structure of the present invention adopts a cooling channel arranged at the rear end of the friction pair (the friction pair is composed of a dynamic ring and a graphite ring), so that the high temperature generated by the friction pair can be heat exchanged through the liquid medium, thereby avoiding dry grinding, thermal cracking, deformation and the like of the friction pair, and also avoiding the vaporization of the liquid medium around the friction pair, which leads to problems such as unstable operation of the mechanical seal, leakage of the sealing surface and even sealing failure.

[0022] 2. The outer circumferential side of the dynamic ring of the present invention is provided with a plurality of guide grooves. When working, the spiral grooves rotate with the rotating shaft, which can accelerate the flow rate of the medium near the friction pair of the mechanical seal, and further prevent the liquid medium around the friction pair from vaporizing due to high temperature.

[0023] 3. The dynamic ring of the present invention adopts a split structure, and an O-type rubber ring is arranged between the ring body and the bushing of the dynamic ring. This structure effectively eliminates the influence of the shaft system fluctuation on the sealing performance of the dynamic ring, and has good floating performance. At the same time, the split structure enhances the heat dissipation capacity of the dynamic ring during the operation of the mechanical seal. In addition, since the guide groove on the outer surface of the dynamic ring needs to meet different rotation directions when the shaft rotates counterclockwise and clockwise, it is convenient to disassemble and replace the dynamic ring.

[0024] 4. The present invention adopts an annular diaphragm group composed of multiple annular sheets with wavy cross-sections to provide axial pressure between the stationary ring seat, the graphite ring and the dynamic ring to achieve a better sealing effect. At the same time, the two sides of the annular diaphragm group are fixedly sealed with the stationary ring seat and the insulation ring by full welding, so that the liquid medium will not leak when passing through the cooling channel.

[0025] 5. The stationary ring seat of the present invention is provided with a stress release annular groove, which can effectively eliminate the influence of stress release of the stationary ring seat on the graphite ring during storage, assembly and use, reduce the deformation of the graphite ring, and improve the working reliability of the mechanical seal.

[0026] 6. The heat-insulating ring of the present invention can effectively block the influence of high-temperature combustion gas of the turbine on the mechanical seal, improve the working environment of the mechanical seal, reduce the tendency of plastic deformation of the diaphragm box in a high-temperature environment, and improve the working reliability of the seal.

[0027] 7. The gap fitting parts in the present invention adopt reasonable sizes, so that when the mechanical seal is working (the maximum PV value is close to 60MPa.m / s), the sealing performance is stable, the friction pair wear area is uniform and smooth, and the lubricating film between the friction pairs is continuous. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the overall structure of the mechanical sealing device of the present invention;

[0029] Figure 2 It is the assembly diagram of the split dynamic ring;

[0030] Figure 3 It is the front view of the ring body;

[0031] Figure 4 When the shaft rotates counterclockwise Figure 3 A-direction view;

[0032] Figure 5 When the shaft rotates clockwise Figure 3 A-direction view;

[0033] Figure 6 It is a schematic diagram of the structure of the stationary ring seat;

[0034] Figure 7 This is a simulation effect diagram of the end surface temperature of the dynamic ring of an existing mechanical seal device;

[0035] Figure 8 This is a simulation effect diagram of the temperature of the end surface of the dynamic ring of the mechanical seal device of the present invention;

[0036] Fig. 9 It is a comparison curve diagram of the test results of the dynamic ring end surface temperature of the existing mechanical seal device and the dynamic ring end surface temperature of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] 1-O-type rubber ring, 2-rotating shaft, 3-annular diaphragm group, 4-moving ring, 5-graphite ring, 6-static ring seat, 7-annular sheet, 8-cavity, 9-annular shell, 10-insulating ring, 11-guide groove, 12-small hole, 17-bushing, 18-ring body, 181-circular ring, 182-annular protrusion, 19-annular boss, 20-stress release annular groove, 21-first anti-rotation groove, 22-first anti-rotation ear, 23-second anti-rotation ear, 24-second anti-rotation groove, 25-liquid medium annular inlet. DETAILED DESCRIPTION

[0039] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0040] The self-forced cooling and high temperature resistant mechanical sealing device provided by the present invention is mainly arranged between the pump inlet and the turbine of the liquid rocket engine turbine pump, and the purpose is to realize the self-forced cooling and high temperature resistance of the seal, and improve the reliability of the sealing work. The present invention can also be used in sealing devices in the fields of ships, nuclear industry, etc., as well as other rotating devices that must ensure sealing, have narrow size and space, require multiple starts and stops, and have a long life.

[0041] like Figure 1 to Figure 6 As shown, the self-forced cooling high temperature resistant mechanical sealing device provided by the present invention mainly comprises an O-type rubber ring 1, a dynamic ring 4, a graphite ring 5, a static ring seat 6, an annular diaphragm group 3, an annular shell 9, and an insulation ring 10.

[0042] The moving ring 4 is fixedly mounted on the end of the rotating shaft 2 close to the pump inlet, and an O-type rubber ring 1 is installed between the inner ring wall of the moving ring 4 and the outer surface of the rotating shaft 2. The stationary ring seat 6 is mounted on the end of the rotating shaft away from the pump inlet. A graphite ring 5 is arranged between the moving ring 4 and the stationary ring seat 6. One end face of the graphite ring 5 contacts the moving ring 4, and the other end face of the graphite ring 5 is gap-matched with the stationary ring seat 6 (the gap is ≤0.03mm).

[0043] The heat-insulating ring 10 is sleeved on the end of the rotating shaft 2 away from the pump inlet and is located behind the stationary ring seat 6; the annular shell 9 is sleeved on the heat-insulating ring 10 and the stationary ring seat 6, and one side of the annular shell 9 is fixedly sealed with the heat-insulating ring 10, and the inner wall of the other side of the annular shell 9 and the outer circular surface of the stationary ring seat 6 form a liquid medium annular inlet 25, the annular diaphragm group 3 is sleeved on the heat-insulating ring 10 and has a gap with the outer ring wall of the heat-insulating ring 10, and the outer edges of the two sides of the annular diaphragm group 3 are fully welded with the stationary ring seat 6 and the heat-insulating ring 10 in the circumferential direction; thus, a cavity 8 is formed between the annular shell 9 and the annular diaphragm group 3; at least two small holes 12 (usually 4-6 holes are arranged in the circumferential direction) connected to the cavity 8 are evenly arranged on the outer wall of the annular shell 9 along the circumferential direction; the liquid medium annular inlet 25, the cavity 8 and the small holes 12 form a cooling channel, which can take away the heat generated by the friction pair in the form of heat exchange, thereby playing a cooling role.

[0044] In order to prevent the liquid medium around the dynamic ring from vaporizing due to high temperature, a plurality of guide grooves 11 are provided along the circumferential direction on the outer surface of the dynamic ring 4. The angle between the guide groove and the flow direction of the liquid medium is α°, 25°<α°<45°, the depth of the guide groove is 0.5~1.5mm, and the width of the guide groove is 3~5mm.

[0045] This leads to another split structure of the moving ring, such as Figure 2 As shown:

[0046] The dynamic ring 4 is a split structure, including a ring body 17 and a bushing 18; the bushing 18 includes a circular ring 181 and an annular protrusion 182 arranged on the end face of the circular ring 181, and the ring body 17 is sleeved on the annular protrusion 182; an O-type rubber ring 1 is also arranged between the ring body 17 and the annular protrusion 182; the end face of the ring body 17 and the end face of the circular ring 181 are gap-matched (the gap here is 0.2-0.5mm). When the split structure is adopted, the guide groove is arranged on the ring body. In addition, the split design can also effectively eliminate the influence of the shaft system fluctuation on the dynamic ring sealing performance, has good floating performance, and at the same time enhances the heat dissipation capacity of the dynamic ring during the operation of the mechanical seal.

[0047] The specific arrangement of the guide groove 11 is determined by the rotation direction of the shaft 2. The purpose is to make the fluid outside the moving ring have good flowability whether the shaft rotates clockwise or counterclockwise. In actual operation, when the shaft rotates clockwise, the arrangement of the guide groove is as follows: Figure 4 As shown in FIG. 1 (the guide groove is arranged on the ring body), when the rotating shaft rotates counterclockwise, the setting mode of the guide groove is as follows: Figure 5 As shown (the guide groove is arranged on the ring body), therefore, in order to adapt to different rotation directions of the shaft, the dynamic ring needs to be replaced according to actual conditions.

[0048] In order to continuously provide axial pressure to the dynamic ring 4, the graphite ring 5 and the static ring seat 6, and at the same time ensure that the liquid medium does not leak when passing through the cooling channel, the annular diaphragm group of the present invention is designed into a structure similar to a sealing bellows: its specific structure is: the annular diaphragm group 3 is welded from left to right along the axial direction of the rotating shaft 2; its specific welding method is: the right outer edge of the inner hole of the first annular plate is welded to the left outer edge of the inner hole of the second annular plate, and the right outer edge of the outer circular surface of the second annular plate is welded to the left outer edge of the outer circular surface of the third annular plate, and this rule is followed until N annular plates are welded; N≥10; in order to ensure the rigidity and deflection of the annular diaphragm group, the cross-section of each annular plate is wavy.

[0049] In order to effectively eliminate the influence of stress release of the stationary ring seat on the graphite ring during storage, assembly and use, the sealing device also makes the following optimized design: an annular boss 19 is provided on the end face of the stationary ring seat 6 that contacts the graphite ring 5, and the inner surface of the annular boss 19 is tightly fitted with the outer circular surface of the graphite ring 5; a stress release annular groove 20 is provided on the inner surface of the annular boss 19.

[0050] When the entire sealing device rotates on the shaft, the movement state between each part is ensured. Anti-rotation design is adopted between multiple parts of the mechanical sealing device, specifically: a first anti-rotation groove 21 is provided on the end face of the ring body 17 that is gap-fitted with the circular ring 181, a first anti-rotation ear 22 that is compatible with the first anti-rotation groove 21 is provided on the circular ring 181, and a second anti-rotation ear 23 is provided on the outer circular surface of the stationary ring seat 6; a second anti-rotation groove 24 that is compatible with the second anti-rotation ear 23 is provided on the inner wall of the annular shell 9.

[0051] One thing that needs to be explained is that the hardness of the dynamic ring is HRC ≥ 35, the graphite ring is pure carbon graphite, the annular piece can be made of 1Cr18Ni9Ti, GH4169 materials, the material of other metal parts is generally 9Cr18, and the O-type rubber ring is generally F207, S8104.

[0052] During operation, the rotating shaft 2 drives the moving ring 4 to rotate at high speed, and the stationary ring seat 6 drives the graphite ring 5 to be stationary relative to the annular shell 9. The annular diaphragm group 3 provides axial compression force to keep the moving ring 4 and the graphite ring 5 in end-face contact at all times to achieve a sealing function. At the same time, the guide groove 11 on the surface of the moving ring makes the liquid medium around it flow more smoothly. The liquid medium between the pump inlet and the turbine flows into the cavity 8 from the liquid medium annular inlet 25 between the annular shell 9 and the stationary ring seat, and then flows out from the small hole 12 on the annular shell 9, thereby cooling the high temperature generated by the front friction pair through liquid heat exchange.

[0053] Simulation results: Figure 7 In order to determine the temperature distribution of the end face of the dynamic ring in the existing sealing device when there is no guide groove and no cooling channel, Figure 8 In order to set the guide groove and the end surface temperature distribution of the dynamic ring in the present invention when there is a cooling channel, under the same boundary conditions and working conditions, the structural design of the present invention is adopted, the agitation of the medium around the friction pair is enhanced, and the temperature gradient of the friction pair is gentle, which is beneficial to prevent problems such as thermal deformation of the friction pair. The temperature is reduced by 7 to 9°C, and the probability of vaporization of the medium around the friction pair is greatly reduced.

[0054] Test results: Tests were conducted on different structures, and the temperature distribution on the end face of the dynamic ring is shown in Fig. 9 ,Under the same boundary conditions and working conditions, after adopting the guide groove and cooling channel structure, the temperature of the friction pair at the same position is 10℃ lower than the end surface temperature of the dynamic ring without the guide groove and cooling channel, which is close to the simulation result and the experimental effect is good.

Claims

1. A self-forced cooling high temperature resistant mechanical sealing device, comprising an O-type rubber ring, a dynamic ring, a graphite ring, a static ring seat, an annular diaphragm group, an annular housing and an insulation ring; The moving ring is fixedly mounted on the end of the rotating shaft close to the pump inlet, and an O-type rubber ring is installed between the inner ring wall of the moving ring and the outer surface of the rotating shaft. The stationary ring seat is mounted on the end of the rotating shaft away from the pump inlet. A graphite ring is arranged between the moving ring and the stationary ring seat, one end face of the graphite ring contacts the moving ring, and the other end face of the graphite ring is in clearance fit with the stationary ring seat. The heat-insulating ring is sleeved on the end of the rotating shaft away from the pump inlet and is located behind the stationary ring seat; the annular shell is sleeved on the heat-insulating ring and the stationary ring seat, and one side of the annular shell is fixedly sealed with the heat-insulating ring, and the inner wall of the other side of the annular shell and the outer circular surface of the stationary ring seat form an annular inlet for liquid medium, the annular diaphragm group is sleeved on the heat-insulating ring and has a gap with the outer ring wall of the heat-insulating ring, and the outer edges of both sides of the annular diaphragm group are fully welded with the stationary ring seat and the heat-insulating ring in the circumferential direction, so that a cavity is formed between the annular shell and the annular diaphragm group; at least two small holes connected to the cavity are evenly arranged on the outer wall of the annular shell in the circumferential direction; the annular inlet for liquid medium, the cavity and the small holes form a cooling channel; The outer circumferential surface of the moving ring is provided with a plurality of guide grooves along the circumferential direction, and the angle between the guide grooves and the flow direction of the liquid medium is α°, 25°<α°<45°; The dynamic ring is a split structure, including a ring body and a bushing; the bushing includes a circular ring and an annular protrusion arranged on the end face of the circular ring, and the ring body is sleeved on the annular protrusion; an O-type rubber ring is also arranged between the ring body and the annular protrusion; the end face of the ring body and the end face of the circular ring are gap-matched; the guide groove is arranged on the outer circumferential surface of the ring body; The gap between the annular diaphragm group and the outer ring wall of the insulation ring is ≤5mm; the depth of the guide groove is 0.5~1.5mm, and the width of the guide groove is 3~5mm; An annular boss is provided on the end surface of the stationary ring seat that contacts the graphite ring, and the inner surface of the annular boss is tightly fitted with the outer circular surface of the graphite ring; a stress release annular groove is provided on the inner surface of the annular boss; The end face of the ring body that is gap-fitted with the circular ring is provided with a first anti-rotation groove, the circular ring is provided with a first anti-rotation ear that matches the first anti-rotation groove, the outer circular surface of the stationary ring seat is provided with a second anti-rotation ear; the inner wall of the annular shell is provided with a second anti-rotation groove that matches the second anti-rotation ear.

2. The self-forced cooling high temperature resistant mechanical sealing device according to claim 1, characterized in that: The annular diaphragm group is formed by welding N annular plates in sequence from left to right along the axial direction of the rotating shaft; the specific welding method is: the right outer edge of the inner hole of the first annular plate is welded to the left outer edge of the inner hole of the second annular plate, and the right outer edge of the outer circular surface of the second annular plate is welded to the left outer edge of the outer circular surface of the third annular plate, and this rule is followed until N annular plates are welded; N≥10.

3. The self-forced cooling high temperature resistant mechanical sealing device according to claim 2 is characterized in that: The cross section of the annular sheet is wavy.

4. The self-forced cooling high temperature resistant mechanical sealing device according to claim 2, characterized in that: The gap between the end face of the graphite ring and the stationary ring seat is ≤0.03mm.

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