A device for applying and measuring friction torque of the main sealing surface of a graphite circumferential seal at zero speed

Abstract

The present invention discloses a device for applying and measuring friction torque of the main sealing surface of a graphite circumferential seal under zero speed, comprising an excitation shaft, an excitation bearing, a tension spring force measuring assembly, a runway assembly, a transmission pin, a split-type graphite ring, a sealing seat assembly and a sealing cavity. The runway assembly is mounted on the excitation shaft through the excitation bearing. One end of the tension spring force measuring assembly is connected to a supporting attachment, and the other end is connected to the runway assembly to provide tension. The transmission pin is arranged on the runway assembly, and the protruding end can contact the circumferential static pressure groove of the split-type graphite ring to transmit torque. The sealing cavity is fixedly mounted on the supporting attachment, and the sealing seat assembly is fixedly mounted on both sides of the sealing cavity. The present invention, through the use of the tension spring assembly and the transmission pin, can realize the transmission of friction torque of the graphite circumferential seal under high-frequency vortex excitation, so as to simulate the wear of the graphite ring anti-rotation groove and the spring groove caused by high-frequency excitation in actual working conditions, and explore the wear law and sealing performance of the contact-type graphite circumferential sealing device.

Description

Technical Field

[0001] The invention belongs to the technical field of aviation engine sealing, and in particular relates to a device for applying and measuring friction torque on a main sealing surface of a graphite circumferential seal in a zero-speed state. Background Art

[0002] As a core component of the main bearing cavity of an aircraft engine, the graphite circumferential seal fulfills the dual mission of isolating the bearing cavity from high-temperature combustion gases and preventing lubricant oil leakage. Its performance directly impacts the engine's reliability and lifespan. During high-speed operation, high-speed rotation and rotor eccentricity cause high-frequency radial vortex motion on the outer surface of the seal runway. Prior art aircraft engine contact-type graphite circumferential seals present two key issues: first, the high-frequency radial vortex motion of the rotating shaft causes fretting wear between the anti-rotation pin and the sidewalls of the anti-rotation groove in the graphite ring; second, high-frequency excitation causes contact and friction between the clamping spring and the outer periphery of the graphite ring. The former is caused by the radial vortex motion of the rotating shaft runway under the friction torque load of the main seal surface, resulting in high-frequency reciprocating fretting wear between the fixed anti-rotation pin mounted on the seal seat and the sidewalls of the anti-rotation groove in the graphite ring. The latter is caused by the vibration of the clamping spring under the high-frequency rotational excitation of the rotating shaft, causing contact and friction with the outer periphery of the graphite ring. These issues severely impact the lifespan and reliability of the seal, necessitating a testing platform that can accurately simulate actual operating conditions. It is necessary to construct a device for the friction torque of the main sealing surface of the circumferential seal on the basis of the existing excitation device, and transfer the torque from the main sealing surface to the graphite groove, so as to better reproduce the above two friction and wear behaviors occurring in the contact graphite circumferential seal, and then study the influence of high-frequency radial vibration of the rotating shaft at high speed on the performance of the graphite circumferential sealing device.

[0003] Currently, research on seal excitation devices has shown that they can be used to simulate external disturbances, but these are all single excitation devices operating at zero speed. For non-contact cylindrical seals, since the main sealing surfaces are not in contact, contact friction cannot be generated, and there is no friction torque or the friction torque is very small. Therefore, a single excitation device can be used to simulate the eccentric excitation wear caused by high speeds. However, for contact-type graphite circumferential seals, since the contact of the main sealing surfaces can generate friction torque, which is applied to the graphite ring anti-rotation groove and the seal seat anti-rotation pin, causing wear there, a single zero-speed radial excitation device cannot be used to simulate the wear mechanism of contact-type graphite cylindrical seals. In other words, existing zero-speed excitation devices lack a torque transmission mechanism and cannot reproduce this critical mechanical environment. It can be seen from this that there is an urgent need to design a device that can simulate the friction torque on the graphite ring caused by the contact friction between the rotating runway and the inner surface of the graphite ring, break through the technical contradiction that "rotation" and "vibration" cannot be achieved at the same time, construct a contact force torque transmission device between the anti-rotation pin and the wall of the mounting groove, and realize the reproduction of the multi-point wear behavior of the contact seal on a single test platform, so that the friction torque generated by the rotation speed can be simulated under a single excitation device, and the wear mechanism and law of the graphite ring anti-rotation groove and the graphite ring sealing secondary end face can be explored. Summary of the Invention

[0004] In order to solve the problems of micro-wear of anti-rotation grooves, spring rubbing and sealing performance degradation caused by high-frequency radial vortex in contact graphite circumferential seals, the present invention provides a device for applying and measuring the friction torque of the main sealing surface of a graphite circumferential seal under zero speed conditions, which can simulate the friction torque of the main sealing surface under zero speed conditions and reproduce the wear behavior in actual working conditions.

[0005] The technical solution of the present invention is:

[0006] A device for applying and measuring friction torque of the main sealing surface of a graphite circumferential seal under zero speed state comprises an external excitation module, a torque applying module, a test sealing module and a supporting accessory. The external excitation module comprises an excitation shaft and an excitation bearing sleeved outside the excitation shaft. The torque applying module comprises a tension spring force measuring assembly, a runway assembly and a transmission pin. The test sealing module comprises a split-type graphite ring, a sealing seat assembly and a sealing cavity. The runway assembly is mounted on the excitation shaft through the excitation bearing. One end of the tension spring force measuring assembly is connected to the supporting accessory, and the other end is connected to the runway assembly to provide tension. The transmission pin is threadedly mounted on the runway assembly and can be extended and retracted radially. The protruding end of the transmission pin can contact the circumferential static pressure groove of the split-type graphite ring provided on the outside of the runway assembly to transmit torque. The sealing cavity is fixedly mounted on the supporting accessory, the sealing seat assembly is fixedly mounted on both sides of the sealing cavity, and the runway assembly passes through the sealing cavity.

[0007] Furthermore, the runway assembly includes a sealed runway, and a torque applying screw is fixedly installed on one or both end surfaces of the sealed runway. One end of the tension spring force measuring assembly is connected to the supporting accessory, and the other end is connected to the torque applying screw to provide tension.

[0008] Furthermore, the tension spring force measuring assembly includes a tensioning spring and a force measuring device. One end of the tensioning spring is fixed to the torque applying screw, and the other end is fixed to the supporting accessory through the force measuring device. The force measuring device is connected to the tensioning spring and dynamically measures the actual applied tension.

[0009] Furthermore, an anti-rotation pin is fixedly installed on the end face of the sealing seat assembly, and the end of the anti-rotation pin extends out of the end face of the sealing seat assembly and is stuck in the anti-rotation groove of the end face of the split graphite ring.

[0010] Furthermore, a threaded hole for installing a pneumatic joint is provided on the outer circumferential surface of the sealing cavity. A sealing chamber is formed between the sealing cavity, the sealing seat assembly and the runway assembly, and the threaded hole is communicated with the sealing chamber.

[0011] Furthermore, the petal-type graphite rings are connected end to end to form an integral graphite ring, a graphite ring circumferential spring groove is provided on the outer side of the graphite ring, and a circumferential tension spring is tightened in the graphite ring circumferential spring groove.

[0012] Furthermore, bearing end covers for limiting the axial displacement of the excitation bearing are provided at the shaft shoulders at both ends of the sealed runway.

[0013] Furthermore, the sealing seat assembly and the sealing cavity are fixed by screw connection, and an auxiliary sealing ring is provided between the two to achieve reliable sealing.

[0014] The working principle of the present invention is:

[0015] The core of this invention lies in its modular design under zero-speed conditions, accurately simulating the wear behavior of contact-type graphite circumferential seals caused by friction torque on the main sealing surface under actual high-speed operating conditions. The sealing cavity is connected to the support accessory via threads, and the left and right sealing seat assemblies are fixed to either side of the cavity, forming a closed pressure chamber. An air inlet and a pressure measuring port are provided in the middle of the cavity, allowing the introduction of a pressure-controlled sealing gas (such as inert gas or compressed air), and the cavity pressure is monitored in real time by a pressure sensor. A set of split-type graphite rings is installed in each of the sealing seat assemblies on either side. The gas in the chamber passes through the leakage channel between the graphite rings and the runway, forming a dynamic leakage flow field, simulating the leakage characteristics of an actual seal pair. One end of the tensioning spring is fixed to the support accessory, and the other end is connected to the torque application screw of the runway assembly. By adjusting the preload of the tensioning spring, the circumferential torque applied to the runway can be precisely controlled, and its value is recorded in real time by a force measuring device; two sets of radially retractable transmission pins are symmetrically arranged at the corresponding positions of the circumferential static pressure groove of the graphite ring; when the split graphite ring is installed, the transmission pin is in a retracted state to avoid friction with the inner surface of the graphite ring; before the test is started, the transmission pin is unscrewed by thread adjustment so that its end is embedded in the circumferential static pressure groove of the split graphite ring, forming a rigid torque transmission path; the circumferential torque generated by the tensioning spring is transmitted to the split graphite ring through the transmission pin, forcing it to generate a circumferential rotation tendency; however, the anti-rotation pin in the sealing seat assembly and the anti-rotation groove on the end face of the graphite ring form a rigid constraint pair, which converts the rotation tendency into a contact load between the side wall of the anti-rotation groove and the anti-rotation pin; this load is generated in the external excitation mode Under the action of the high-frequency radial vortex of the block, reciprocating wear of the side wall of the anti-rotation groove is induced, accurately reproducing the wear pattern in actual working conditions; the external excitation module applies radial or angular vortex with adjustable amplitude and frequency to the runway assembly through the combination of the excitation shaft and the excitation bearing; the vortex simulates the dynamic eccentricity effect of the aircraft engine rotor during high-speed rotation, resulting in periodic relative displacement between the petal-type graphite ring and the main sealing surface of the runway. At the same time, the circumferential tension spring continuously applies radial tightening force to the graphite ring to ensure the stability of the contact pressure of the main sealing surface; under the coupling action of high-frequency vortex and friction torque, high-frequency micro-motion wear is generated between the side wall of the anti-rotation groove of the graphite ring and the anti-rotation pin, and the contact and friction behavior between the circumferential tension spring and the non-installation surface of the outer periphery of the graphite ring is also synchronously excited, fully simulating the multi-point wear mechanism of the sealing device.

[0016] The beneficial effects of the present invention are:

[0017] (1) It can accurately simulate the friction torque of the main sealing surface from the rotating shaft during the actual operation of the contact graphite circumferential seal, and can accurately control the friction torque of the main sealing surface by replacing the tension springs with different stiffnesses, adapting to the test requirements under different medium pressures, and providing a reliable test platform for the experimental research on the influence of graphite ring anti-rotation groove wear caused by rotor radial excitation under different medium pressures;

[0018] (2) Through the coordination of the tension spring, the excitation bearing and the transmission pin, the friction torque of the main sealing surface caused by high speed can be better simulated, and the size of the friction torque under different medium pressures can be controlled by changing the design of the tension spring;

[0019] (3) The overall structure is compact, and key components such as the transmission pin and tension spring assembly can be quickly disassembled and assembled. The transmission and cancellation of the friction torque of the main sealing surface can be achieved by tightening and loosening the transmission pin;

[0020] (4) Support pressurized / non-pressurized sealing chamber tests, and simultaneously observe the wear of the anti-rotation groove and the friction behavior of the spring, providing reliable data for seal life evaluation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the three-dimensional structure of the entire contact-type graphite circumferential sealing device according to an embodiment of the present invention;

[0022] Figure 2 This is a front view schematic diagram of an embodiment of the present invention after removing the supporting accessories

[0023] Figure 3 is a cross-sectional view of an embodiment of the present invention when only one torque applying screw is provided;

[0024] Figure 4 Schematic diagram of a single-ring structure of a split-petal graphite ring according to an embodiment of the present invention;

[0025] Figure 5 It is a cross-sectional view of the transmission pin and circumferential static pressure groove structure of an implementation case of the present invention.

[0026] In the figure: 1. External excitation module; 11. Excitation shaft; 12. Excitation bearing; 2. Torque application module; 21. Tension spring force measuring assembly; 211. Tensioning spring; 212. Force measuring device; 22. Runway assembly; 221. Sealing runway; 222. Torque application screw; 223. Bearing end cover; 23. Transmission pin; 3. Test sealing module; 31. Split graphite ring; 311. Circumferential static pressure groove; 312. Anti-rotation groove; 313. Circumferential spring groove of graphite ring; 32. Sealing seat assembly; 321. Anti-rotation pin; 33. Sealing cavity; 331. Threaded hole; 332. Auxiliary sealing ring; 34. Circumferential tension spring; 35. Sealing cavity; 4. Support accessories. DETAILED DESCRIPTION

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments, but the protection scope of the present invention is not limited thereto.

[0028] Example 1

[0029] Reference Figure 1-4A device for applying and measuring friction torque on the main sealing surface of a graphite circumferential seal under zero speed conditions includes an external excitation module 1, a torque application module 2, a test seal module 3, and a support accessory 4. The external excitation module 1 includes an excitation shaft 11 and an excitation bearing 12. The torque application module 2 includes a tension spring force measurement assembly 21, a runway assembly 22, and a drive pin 23. The test seal module 3 includes a split-type graphite ring 31, a seal seat assembly 32, a seal cavity 33, a circumferential tension spring 34, and a seal chamber 35.

[0030] The tension spring force measuring assembly 21 includes a tensioning spring 211 and a force measuring device 212. The runway assembly 22 includes a sealing runway 221, a torque applying screw 222 and a bearing end cover 223. The sealing runway 221 is installed on the excitation shaft 11 through the excitation bearing 12. The circumferential displacement property of the excitation bearing 12 can realize the transmission of friction torque. A torque applying screw 222 is fixedly installed on one side or both side end faces of the sealing runway 221. One end of the tensioning spring 211 is connected to the force measuring device 212, and the force measuring device 212 is fixed to the support attachment 4. The other end of the tensioning spring 211 is connected to the torque applying screw 222. The tension of the tensioning spring 211 is realized by circumferential cooperation with the excitation bearing 12. The friction torque of the main sealing surface is added to the runway assembly 22; the split graphite ring 31 is arranged on the outside of the sealing runway 221, and multiple split graphite rings 31 are connected end to end to form an integral graphite ring. The outer circumferential surface of the split graphite ring 31 is provided with an anti-rotation groove 312 and a graphite ring circumferential spring groove 313, and the circumferential tension spring 34 is tightened in the graphite ring circumferential spring groove 313. The sealing cavity 33 is fixedly mounted on the supporting attachment 4, and the sealing seat assembly 32 is fixedly mounted on both sides of the sealing cavity 33. The runway assembly 22 passes through the sealing cavity 33, and the sealing seat assembly 32 and the sealing cavity 33 are fixed by screws. An auxiliary sealing ring 332 is provided between the two to achieve reliable sealing. The sealing seat assembly 32 An anti-rotation pin 321 is fixedly installed on the end face by threads, and the end of the anti-rotation pin 321 extends out of the end face of the sealing seat assembly 32 and is stuck in the anti-rotation groove 312 of the end face of the split graphite ring 31. The anti-rotation pin 321 cooperates with the end face anti-rotation groove 312 on each split graphite ring 31 to limit the circumferential displacement of the split graphite ring 31. A threaded hole 331 for installing a pneumatic joint is provided on the outer circumferential surface of the sealing cavity 33 to realize the application of medium pressure and pressure measurement. A sealing chamber 35 is formed between the sealing cavity 33, the sealing seat assembly 32 and the runway assembly 22. The threaded hole 331 is connected to the sealing chamber 35. At the end of the circumferential static pressure groove 311 corresponding to each petal of the split graphite ring 31 on the sealing runway 221 Two transmission pins 23 are provided at the end positions. The transmission pins 23 are threadedly installed on the sealing runway 221. The transmission pins 23 can realize radial expansion and contraction through the threads. When the split graphite ring 31 is installed, the ends of the transmission pins 23 do not extend out of the surface of the sealing runway 221. After the split graphite ring 31 is installed in place, the transmission pins 23 are screwed out through the inner hole of the sealing runway 221 and the ends thereof extend out of the surface of the sealing runway 221 and then are clamped into the circumferential static pressure groove 311 on the inner surface of the split graphite ring 31, so that the torque of the tensioning spring 211 acting on the sealing runway 221 is transmitted to the split graphite ring 31 through the transmission pins 23, and finally transmitted to between the anti-rotation pin 321 and the side wall of the anti-rotation groove 312 on the end face of the graphite ring;This torque transmission method can simulate the friction torque of the main sealing surface under zero-speed conditions. Furthermore, because the split-shaped graphite ring 31 and the sealing raceway 221 are tightly held and not subject to radial displacement, friction between them can be significantly reduced, preventing damage to the graphite ring's circumferential static pressure groove 311. Bearing end caps 223 are located at the shoulders at both ends of the sealing raceway 221 to limit the axial displacement of the excitation bearing 12.

[0031] The radial force provided by the circumferential tension spring 34 to the split graphite ring 31 is the pressure source of the actual friction torque of the main sealing surface. Under the excitation of the external excitation module 1, the circumferential tension spring 34 and the non-installation surface of the outer peripheral surface of the graphite ring will produce contact and friction, thereby causing severe wear. This will cause the radial thickness of the non-installation section to be sharply thinned, thereby affecting the strength of the graphite ring and increasing deformation. Therefore, it is necessary to observe the wear of the graphite ring caused by the excitation of the circumferential tension spring 34 while observing the wear of the anti-rotation groove 312 on the end face of the graphite ring.

[0032] The contents described in the embodiments of this specification are merely an enumeration of the implementation forms of the inventive concept. The scope of protection of the present invention should not be regarded as limited to the specific forms described in the embodiments. The scope of protection of the present invention also extends to equivalent technical means that can be conceived by those skilled in the art based on the inventive concept.

Claims

1. A device for applying and measuring friction torque on the main sealing surface of a graphite circumferential seal under zero speed, characterized in that: The invention comprises an external excitation module (1), a torque application module (2), a test sealing module (3) and a supporting accessory (4), wherein the external excitation module (1) comprises an excitation shaft (11) and an excitation bearing (12) sleeved outside the excitation shaft (11), the torque application module (2) comprises a tension spring force measuring assembly (21), a runway assembly (22) and a transmission pin (23), the test sealing module (3) comprises a split-type graphite ring (31), a sealing seat assembly (32) and a sealing cavity (33), the runway assembly (22) is mounted on the excitation shaft (11) through the excitation bearing (12), the tension spring force measuring assembly (21) and the transmission pin (23), and the test sealing module (3) comprises a split-type graphite ring (31), a sealing seat assembly (32) and a sealing cavity (33). One end of the force assembly (21) is connected to the support attachment (4), and the other end is connected to the runway assembly (22) to provide tension. The transmission pin (23) is threadedly installed on the runway assembly (22) and can be extended and retracted in the radial direction. The extended end of the transmission pin (23) can contact the circumferential static pressure groove (311) of the split-type graphite ring (31) provided on the outside of the runway assembly (22) to transmit torque. The sealing cavity (33) is fixedly installed on the support attachment (4), the sealing seat assembly (32) is fixedly installed on both sides of the sealing cavity (33), and the runway assembly (22) passes through the sealing cavity (33).

2. The device for applying and measuring friction torque of the main sealing surface of a graphite circumferential seal under zero speed according to claim 1, characterized in that: The runway assembly (22) includes a sealed runway (221), and a torque applying screw (222) is fixedly mounted on one or both end surfaces of the sealed runway (221). One end of the tension spring force measuring assembly (21) is connected to the support attachment (4), and the other end is connected to the torque applying screw (222) to provide tension.

3. The device for applying and measuring friction torque of the main sealing surface of a graphite circumferential seal under zero speed according to claim 2, characterized in that: The tension spring force measuring assembly (21) comprises a tensioning spring (211) and a force measuring device (212), one end of the tensioning spring (211) is fixed to the torque applying screw (222), and the other end is fixed to the supporting attachment (4) through the force measuring device (212), and the force measuring device (212) is connected to the tensioning spring (211) and dynamically measures the actual applied tension.

4. The device for applying and measuring friction torque of the main sealing surface of a graphite circumferential seal under zero speed according to claim 1, characterized in that: An anti-rotation pin (321) is fixedly mounted on the end face of the sealing seat assembly (32), and an end portion of the anti-rotation pin (321) extends out of the end face of the sealing seat assembly (32) and is engaged in the anti-rotation groove (312) on the end face of the split-type graphite ring (31).

5. The device for applying and measuring friction torque of the main sealing surface of a graphite circumferential seal under zero speed according to claim 1, characterized in that: A threaded hole (331) for mounting a pneumatic joint is provided on the outer circumferential surface of the sealing cavity (33). A sealing chamber (35) is formed between the sealing cavity (33), the sealing seat assembly (32) and the runway assembly (22). The threaded hole (331) is in communication with the sealing chamber (35).

6. The device for applying and measuring friction torque of the main sealing surface of a graphite circumferential seal under zero speed according to claim 1, characterized in that: The split-type graphite ring (31) is connected end to end to form an integral graphite ring. A graphite ring circumferential spring groove (313) is provided on the outside of the graphite ring. A circumferential tension spring (34) is tightly clamped inside the graphite ring circumferential spring groove (313).

7. The device for applying and measuring friction torque of the main sealing surface of a graphite circumferential seal under zero speed according to claim 2, characterized in that: Bearing end covers (223) for limiting the axial displacement of the excitation bearing (12) are provided at the shaft shoulders at both ends of the sealing runway (221).

8. The device for applying and measuring friction torque of the main sealing surface of a graphite circumferential seal under zero speed according to claim 2, characterized in that: The sealing seat assembly (32) and the sealing cavity (33) are connected and fixed by screws, and an auxiliary sealing ring (332) is provided between the two to achieve reliable sealing.

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