A device and method for testing hysteresis characteristics of dry gas seals

Abstract

The present invention discloses a device and method for testing the hysteresis characteristics of dry gas seals, the device comprising a power system, a sliding spiral transmission structure, and a rotating shaft bracket; the sliding spiral transmission structure comprises a screw and a nut structure; the output end of the power system is connected to one end of the screw, the nut structure is mounted on the screw, one end of the rotating shaft is fixed to the nut structure, and the rotating shaft is supported by the rotating shaft bracket, so as to drive the rotating shaft to perform linear motion with the nut structure through the output motion of the power system. The present invention realizes the axial displacement of the rotating shaft in the dry gas seal structure through the sliding spiral transmission structure; by utilizing the coordination between sensors, the change of the spring elastic force in the dry gas seal and the change of the friction force of the sealing ring in the dry gas seal structure can be obtained through calculation; the change of the hysteresis phenomenon in the dry gas seal can be measured more accurately, conveniently, and intuitively through the dry gas seal hysteresis curve.

Description

Technical Field

[0001] The invention relates to a device and method for testing hysteresis characteristics of dry gas seals, belonging to the technical field of mechanical seals. Background Art

[0002] Dry gas seal (dry running gas seal) is a new type of rotating machinery shaft end seal that uses slotted sealing technology for gas sealing. It is a non-contact seal. As a sealing device with relatively good sealing effect among the current rotating machinery shaft end seals, dry gas seal is used in many scenarios.

[0003] The working principle of dry gas seal is that when the dynamic ring rotates, the fluid dynamic pressure groove pumps the high-pressure isolation gas on the outer diameter side into between the sealing end faces. The air film pressure gradually increases from the outer diameter to the groove diameter, and gradually decreases from the groove diameter to the inner diameter. The increase in film pressure at the end face makes the opening force formed greater than the closing force acting on the sealing ring, and a very thin layer of air film will be formed between the friction pairs, so that the seal works in a non-contact state. The formed air film completely blocks the relatively low-pressure sealing medium leakage channel, achieving zero leakage or zero escape of the sealing medium.

[0004] In the dry gas sealing system, the auxiliary sealing ring is an important component of the dry gas sealing structure and is used as an auxiliary seal; the sealing ring not only plays the role of realizing the protection of the main seal, but also plays the role of compensating for the deflection, vibration and movement of the sealing end face and the shaft. Since the auxiliary sealing ring is usually made of materials such as fluororubber, silicone rubber, polymer sealing ring, etc., which are superelastic bodies, the movement of the sealing ring will show complex micro-motion characteristics. The sealing ring will show various states such as relative stillness, partial slip, discontinuous slip, and complete slip during operation. In the dry gas sealing system, the movement state of the sealing ring has a certain influence on the steady-state performance and dynamic characteristics of the dry gas sealing system. However, due to the special material properties and installation position of the sealing ring, the friction force of the sealing ring in the dry gas sealing system is difficult to detect, so there is a lack of corresponding detection devices in the prior art.

[0005] The reason for the dry gas seal hysteresis phenomenon is that in the dry gas seal system, the shaft will be displaced in the axial direction of the shaft when it is working. When the shaft is displaced in the axial direction, it will obviously affect the change in the direction of the friction force of the seal ring in the dry gas seal structure and the change in the magnitude of the friction force of the seal ring. Since the direction of the friction force of the seal ring in the dry gas seal structure and the magnitude of the friction force of the seal ring have changed, the closing force of the dry gas seal structure is inconsistent during the process of starting work and stopping work, thereby affecting the normal operation of the dry gas seal structure. Therefore, the study of the dry gas seal hysteresis phenomenon is of great significance to the dry gas seal structure.

[0006] Currently, there are few test methods and means for studying and measuring the dry gas seal hysteresis phenomenon in the prior art, and there are relatively few invention studies on the dry gas seal hysteresis phenomenon. Summary of the invention

[0007] The present invention provides a device and method for testing hysteresis characteristics of dry gas seals, which are used to construct a platform suitable for testing hysteresis characteristics of dry gas seals, and further adopting the device for testing hysteresis characteristics of dry gas seals can realize hysteresis characteristics testing suitable for dry gas seals.

[0008] The technical solution of the present invention is: a device suitable for testing the hysteresis characteristics of dry gas seals, comprising a power system 1, a sliding spiral transmission structure, and a rotating shaft bracket 6; the sliding spiral transmission structure comprises a screw 3 and a nut structure 4; the output end of the power system 1 is connected to one end of the screw 3, the nut structure 4 is installed on the screw 3, one end of the rotating shaft 17 is fixed to the nut structure 4, and the rotating shaft 17 is supported by the rotating shaft bracket 6, so that the output movement of the power system 1 drives the rotating shaft 17 to perform linear motion with the nut structure 4.

[0009] Optionally, a dry gas sealing structure 5 is installed on the rotating shaft 17, and holes are opened on the shell 7 and the spring seat 8 in the dry gas sealing structure 5 for installing distance sensor I13 and distance sensor II21, so as to measure the distance change of spring I14 in the dry gas sealing structure 5 through distance sensor I13 and measure the distance change of spring II20 in the dry gas sealing structure 5 through distance sensor II21.

[0010] Optionally, one end of the rotating shaft 17 away from the nut structure 4 cooperates with a linear sliding bearing 22 installed in the bracket housing 23, and a tension and pressure sensor 25 fixed on the bracket housing 23 is connected to the end of the rotating shaft 17 using a spring III 24.

[0011] Optionally, the nut structure 4 is arranged in an upper and lower manner, the lower part of the nut structure 4 cooperates with the screw rod 3, and the upper part of the nut structure 4 is equipped with a thrust cylindrical roller bearing to cooperate with one end of the rotating shaft 17.

[0012] According to another aspect of the embodiment of the present invention, a method for testing hysteresis characteristics of dry gas seal is provided, which is performed using the above-mentioned device for testing hysteresis characteristics of dry gas seal, and specifically includes:

[0013] S1, by introducing gas into the air inlet of the housing 7 in the dry gas sealing structure, the pressure in the sealing cavity of the dry gas sealing structure is kept constant;

[0014] S2, the power system 1 works to drive the rotating shaft 17 to move, and the axial movement distance S of the rotating shaft 17 is obtained;

[0015] S3, measuring the distance change △x1 of the spring Ⅰ14 in the dry gas sealing structure 5 through the distance sensor Ⅰ13, and measuring the distance change △x2 of the spring Ⅱ20 in the dry gas sealing structure 5 through the distance sensor Ⅱ21;

[0016] S4. According to the measured length change △x of the spring and the spring stiffness Ks obtained during installation, the real-time change of the spring force in the dry gas seal structure is calculated by using the elastic Hooke's law, and the spring forces of spring I14 and spring II20 in the dry gas seal structure are recorded as △Fs1 and △Fs2 respectively; wherein △x is △x1 and △x2;

[0017] S5, the tension and pressure sensor 25 is used to measure the axial force Fn exerted on the rotating shaft 17;

[0018] S6. The friction force Ff of a single sealing ring in the dry gas seal structure is obtained by calculating the obtained elastic force △Fs1 of the spring I 14, the elastic force △Fs2 of the spring II 20, the axial force Fn exerted on the rotating shaft 17, and the friction force Ff1 between the rotating shaft 17 and the linear sliding bearing 22 measured in advance;

[0019] S7. Draw a dry gas seal hysteresis curve by obtaining the axial displacement S of the rotating shaft 17, the spring force △Fs, and the sealing ring friction force Ff.

[0020] Optionally, the axial force Fn exerted on the rotating shaft 17 is Fn=ΔFs1+ΔFs2+2*Ff+Ff1.

[0021] Optionally, the horizontal axis of the dry gas seal hysteresis curve represents the axial displacement S, and the vertical axis represents the sum of the spring force △Fs and the sealing ring friction force Ff; wherein, the spring force △Fs and the sealing ring friction force Ff represent the elastic force of spring I14 and the friction force of sealing ring I15, or represent the elastic force of spring II20 and the friction force of sealing ring II19.

[0022] The beneficial effects of the present invention are as follows: the present invention realizes axial displacement of the rotating shaft in the dry gas sealing structure through a sliding spiral transmission structure; by utilizing the cooperation between sensors, the force exerted on the rotating shaft in the dry gas sealing structure and the real-time change of the spring in the dry gas sealing structure can be obtained, and the change of the spring elastic force in the dry gas seal and the change of the friction force of the sealing ring in the dry gas sealing structure can be obtained by calculation; furthermore, a dry gas seal hysteresis curve diagram can be drawn by a computer, and the change of the hysteresis phenomenon in the dry gas seal can be measured more accurately, conveniently and intuitively through the dry gas seal hysteresis curve diagram. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of a dry gas seal hysteresis characteristic testing device applicable to the present invention;

[0024] Figure 2 It is a structural schematic diagram of the dry gas sealing structure of the present invention;

[0025] Figure 3 This is a diagram showing the installation position of the tension and pressure sensor of the present invention;

[0026] Figure 4 This is the optical path diagram of the distance sensor of the present invention;

[0027] Figure 5 This is a schematic diagram of a hysteresis curve of Example 3 of the present invention;

[0028] Figure 6 This is a schematic diagram of a hysteresis curve of Example 4 of the present invention;

[0029] Figure 7 This is a schematic diagram of a hysteresis curve of Example 5 of the present invention;

[0030] The numbers in the figure are: 1-power system, 2-sliding spiral transmission structure bracket, 3-screw, 4-nut structure, 5-dry gas sealing structure, 6-rotating shaft bracket, 7-housing, 8-spring seat, 9-static ring, 10-dynamic ring, 11-screw, 12-push ring, 13-distance sensor I, 14-spring I, 15-sealing ring I, 16-sealing component, 17-rotating shaft, 18-sleeve, 19-sealing ring II, 20-spring II, 21-distance sensor II, 22-linear sliding bearing, 23-bracket housing, 24-spring III, 25-tension pressure sensor, 26-pinhole in distance, 27-lens. DETAILED DESCRIPTION

[0031] The invention is further described below in conjunction with the accompanying drawings and embodiments, but the content of the invention is not limited to the scope of the embodiments.

[0032] Example 1: Figure 1-Figure 4 As shown, a device suitable for testing the hysteresis characteristics of dry gas seals includes a power system 1, a sliding spiral transmission structure, and a rotating shaft bracket 6; the sliding spiral transmission structure includes a screw rod 3 and a nut structure 4; the output end of the power system 1 is connected to one end of the screw rod 3, the nut structure 4 is installed on the screw rod 3, one end of the rotating shaft 17 is fixed to the nut structure 4, and the rotating shaft 17 is supported by the rotating shaft bracket 6, so that the output movement of the power system 1 drives the rotating shaft 17 to perform linear motion with the nut structure 4.

[0033] Optionally, a dry gas sealing structure 5 is installed on the rotating shaft 17, and holes are opened on the shell 7 and the spring seat 8 in the dry gas sealing structure 5 for installing distance sensor I13 and distance sensor II21, so as to measure the distance change of spring I14 in the dry gas sealing structure 5 through distance sensor I13 and measure the distance change of spring II20 in the dry gas sealing structure 5 through distance sensor II21.

[0034] It should be noted that the dry gas seal structure is a double-end dry gas seal structure, that is, two sets of dry gas seals are installed face to face. According to experiments, the double-end dry gas seal structure is used, the shaft is balanced in force, and the gas pressure in the sealed cavity can maintain a stable value. Specifically, the dry gas seal structure used in the present invention is installed on the shaft 17, and its structure diagram is as shown in FIG. Figure 2 As shown, it includes a shell 7, and the shell 7 of the dry gas sealing structure 5 is divided into two parts, which are connected by screws 11; the shell 7 is supported and fixed by a dry gas sealing structure bracket; it also includes two groups of spring seats 8, static rings 9, dynamic rings 10, push rings 12, springs, sealing rings, sealing components 16, and sleeves 18 (wherein the springs and sealing rings are spring I 14, sealing rings I 15, sealing rings II 19, and springs II 20); springs I 14 and springs II 20 are symmetrically installed between the push ring 12 and the spring seat 8, respectively, and distance sensors I 13 and II 21 are used to measure the dry gas The distance change between the push ring 12 and the spring seat 8 in the sealing structure 5 is equal to the length change of the spring Ⅰ14 / spring Ⅱ20 because both ends of the spring Ⅰ14 and the spring Ⅱ20 are respectively in close contact with the push ring 12 and the spring seat 8 on the corresponding side. Therefore, the distance sensor Ⅰ13 is used to measure the distance change of the spring Ⅰ14 in the dry gas sealing structure 5, and the distance sensor Ⅱ21 is used to measure the distance change of the spring Ⅱ20 in the dry gas sealing structure 5. The working principles of the distance sensor Ⅰ13 and the distance sensor Ⅱ21 in the present invention are as follows: Figure 4 As shown, the light of the distance sensor is projected to the push ring 12 through the lens 27, reflected to the distance sensor on the surface of the push ring, and received and processed through the inner pinhole 26; the elastic force change of the spring I14 in the dry gas sealing structure 5 is calculated based on the data measured by the distance sensor I13, and the elastic force change of the spring II20 in the dry gas sealing structure 5 is calculated based on the data measured by the distance sensor II21. In this way, the distance sensor I13 and the distance sensor II21 set in the above manner do not need to be in direct contact with the push ring 12, and can be effectively used to measure the distance change between the push ring 12 and the spring seat 8 in the dry gas sealing structure 5; at the same time, the movement of the push ring is not affected by resistance, and has no effect on the change of the spring, so that the measurement result is more accurate.

[0035] Optionally, one end of the rotating shaft 17 away from the nut structure 4 cooperates with a linear sliding bearing 22 installed in the bracket housing 23, and a tension and pressure sensor 25 fixed on the bracket housing 23 is connected to the end of the rotating shaft 17 using a spring III 24.

[0036] Optionally, the nut structure 4 is arranged in an upper and lower manner, the lower part of the nut structure 4 cooperates with the screw rod 3, and the upper part of the nut structure 4 is equipped with a thrust cylindrical roller bearing to cooperate with one end of the rotating shaft 17.

[0037] Specifically, the installation position diagram of the tension and pressure sensor used in the present invention is as follows: Figure 3 As shown, in the bracket shell installed on the upper part of the shaft bracket 6 on the end face side of the shaft, one end of the tension pressure sensor 25 is fixed on the bracket shell 23, and the other end of the tension pressure sensor 25 is connected to the shaft 17 by a spring III 24. In this way, when the shaft 17 is subjected to force and moves, the spring III 24 is deformed. Through the action of the spring III 24, the force exerted on the shaft 17 is the same as the force exerted on the tension pressure sensor 25. The spring III 24 can ensure that the shaft can stably move axially for a sufficiently long displacement, thereby ensuring that the tension pressure sensor 25 can accurately measure the force exerted on the shaft; that is, the magnitude of the force exerted on the shaft 17 in the dry gas sealing structure 5 can be indirectly measured through the tension pressure sensor 25.

[0038] Optionally, the power system 1 uses a motor. When it is used, a computer can be connected to the motor. The computer controls the motor to work. The rotor of the motor is connected to the screw 3 through a coupling. The rotation of the rotor of the motor 1 drives the screw 3 to rotate. The screw 3 is fixed by a sliding spiral transmission structure bracket 2. The screw 3 is connected to the nut structure 4. The relative movement of the screw 3 and the nut structure 4 is used to convert the rotational motion into a linear motion. A thrust cylindrical roller bearing is installed above the nut structure 4 to cooperate with the rotating shaft 17. The rotating shaft 17 is fixed by a rotating shaft bracket 6. When the screw 3 rotates, the nut structure 4 is driven to move horizontally. The horizontal movement of the nut structure 4 drives the rotating shaft 17 to move horizontally. In the rotating shaft bracket on the other side of the fixed rotating shaft 17, the rotating shaft 17 is fixed by a linear sliding bearing 22. Among them, the nut structure is arranged up and down, which can ensure that the screw 3 and the rotating shaft can achieve power transmission without interfering with each other.

[0039] In this way, by applying the technical solution of this embodiment, power is provided by the power system 1, so that the shaft can be ensured to move axially stably. Specifically: on the one hand, the screw 3 and the shaft are supported by the bracket, so that the force is more uniform and the stability is stronger; on the other hand, a thrust cylindrical roller bearing is used to cooperate with one end of the shaft 17, and the thrust cylindrical roller bearing has uniform pressure distribution between the roller and the raceway surface, can withstand unidirectional axial load, has large axial load capacity, and has strong axial rigidity, which can ensure that the dry gas seal shaft can move axially stably; further, the other end of the shaft 17 is fixed with a linear sliding bearing 22, and the linear sliding bearing will generate dynamic friction resistance when working, and the dynamic friction resistance is extremely small. The friction coefficient of the linear sliding bearing is stable, and it has the characteristics of maintaining constant accuracy for a long time, thereby further ensuring that the dry gas seal shaft can move axially stably.

[0040] Embodiment 2: A method for testing hysteresis characteristics of dry gas seals, characterized in that: the method is performed using the above-mentioned device for testing hysteresis characteristics of dry gas seals, and specifically includes:

[0041] S1, by introducing gas into the air inlet of the housing 7 in the dry gas sealing structure, the pressure in the sealing cavity of the dry gas sealing structure is kept constant;

[0042] S2, the power system 1 works to drive the rotating shaft 17 to move, and the axial movement distance S of the rotating shaft 17 is obtained;

[0043] S3, measuring the distance change △x1 of the spring Ⅰ14 in the dry gas sealing structure 5 through the distance sensor Ⅰ13, and measuring the distance change △x2 of the spring Ⅱ20 in the dry gas sealing structure 5 through the distance sensor Ⅱ21;

[0044] S4. According to the measured length change △x of the spring and the spring stiffness Ks obtained during installation, the real-time change of the spring force in the dry gas seal structure is calculated by elastic Hooke's law (i.e., △Fs=Ks*|△x|), and the spring forces of spring I14 and spring II20 in the dry gas seal structure are recorded as △Fs1 and △Fs2 respectively; wherein, △x is △x1 and △x2; that is, by substituting △x1 into the above formula, △Fs1 is obtained, and by substituting △x2 into the above formula, △Fs2 is obtained;

[0045] S5, the tension and pressure sensor 25 is used to measure the axial force Fn exerted on the rotating shaft 17;

[0046] S6. The friction force Ff of a single sealing ring in the dry gas seal structure is obtained by calculating the obtained elastic force △Fs1 of the spring I 14, the elastic force △Fs2 of the spring II 20, the axial force Fn exerted on the rotating shaft 17, and the friction force Ff1 between the rotating shaft 17 and the linear sliding bearing 22 measured in advance;

[0047] S7. Draw a dry gas seal hysteresis curve using a computer by obtaining the axial displacement S of the rotating shaft 17, the spring force ΔFs, and the sealing ring friction force Ff.

[0048] Optionally, the axial force Fn exerted on the rotating shaft 17 is:

[0049] Optionally, the horizontal axis of the dry gas seal hysteresis curve represents the axial displacement S, and the vertical axis represents the sum of the spring force △Fs and the sealing ring friction force Ff; wherein, the spring force △Fs and the sealing ring friction force Ff represent the elastic force of spring I14 and the friction force of sealing ring I15, or represent the elastic force of spring II20 and the friction force of sealing ring II19.

[0050] In the specific implementation process, the power system 1 can be connected to a computer, and the operation of the power system can be controlled by the computer. The computer controls the output pulse control signal, which is amplified by the driving circuit so that the power system works in the required direction and speed to obtain the linear movement distance of the nut structure; and the rotor of the power system 1 is connected to the screw 3, and the movement of the screw 3 in the sliding spiral transmission structure drives the nut structure 4 installed on the screw 3 to move horizontally; the thrust cylindrical roller bearing is installed above the rotating shaft and the nut structure 4 to connect the rotating shaft to realize the horizontal movement of the rotating shaft with the nut structure 4, thereby obtaining the axial movement distance S of the rotating shaft controlled by the power system. In addition, for the sliding spiral transmission structure, the nut is of integral type, the thread is of trapezoidal thread, the nut is made of cast iron, the screw is made of 45 steel, and the number of thread lines is 1; the material of the rotating shaft 17 is 45 steel, the density is 7.85g / cm^3, the volume is regarded as a cylinder, the radius is 4.5cm, the height is 40cm, and the calculated result is about 19.98Kg; the friction coefficient of the linear sliding bearing 22 is 0.005~0.015, and 0.01 is selected in the specific example; the sealing ring material is fluororubber material.

[0051] When the dry gas sealing structure 5 is working, the sealing ring I15 and the sealing ring II19 in the dry gas sealing structure 5 are deformed by the pressure of the gas coming from the air inlet on the shell 7 and the extrusion of the push ring 12 and the static ring 9, and the double-end dry gas sealing structure can balance the gas pressure and keep the gas pressure in the sealing cavity at a stable value. When the power system provides power, the push ring 12 moves with the movement of the rotating shaft 17, and friction will be generated between the push ring 12 and the spring seat 8. Since the sealing ring I15 and the sealing ring II19 are superelastic bodies, the deformation is difficult to predict and the calculation is relatively complicated. The calculation is performed by the force balance method. The elastic force change of the spring I14 in the dry gas sealing structure 5, the elastic force change of the spring II20 in the dry gas sealing structure 5 and the tension pressure sensor 25 are used to measure the force change of the rotating shaft 17 in the dry gas sealing structure 5. The friction force of the linear sliding bearing 22 obtained before installation is calculated by the force balance principle. Since the materials and specifications of the sealing rings I15 and II19 in the dry gas sealing structure 5 are the same, the working conditions of the sealing rings I15 and II19 are basically the same, and the friction force of a single sealing ring in the dry gas sealing structure 5 can be calculated;

[0052] The hysteresis curve drawing method of the present invention draws a dry gas sealing hysteresis curve through the displacement of the rotating shaft 17 in the dry gas sealing structure 5, the elastic force change of the spring II 20 in the dry gas sealing structure 5 and the friction force change of the sealing ring II 19 in the dry gas sealing structure 5; in the hysteresis curve diagram, the horizontal axis is represented by the displacement of the rotating shaft 17 in the dry gas sealing structure 5, and the vertical axis is represented by the sum of the elastic force of the spring II 20 in the dry gas sealing structure 5 and the friction force of the sealing ring II 19 in the dry gas sealing structure 5.

[0053] The following is a detailed description of the optional implementation methods applicable to the dry gas seal hysteresis characteristics test method.

[0054] Embodiment 3:

[0055] (1) By introducing gas into the air inlet of the shell in the dry gas sealing structure, the pressure in the sealed cavity of the dry gas sealing structure is maintained at 2 MPa;

[0056] (2) Connect the power system to a computer and control the operation of the power system through the computer. The computer controls the output pulse control signal, which is amplified by the drive circuit so that the power system works in the required direction and speed. The power system is used to control the axial movement distance of the rotating shaft and control the axial movement of the rotating shaft in the dry gas sealing structure by 1 mm.

[0057] (3) Connect the rotor of the power system to the screw of the sliding screw transmission structure, and drive the screw in the sliding screw transmission structure to move through the rotation of the rotor of the power system, and drive the nut structure in the sliding screw transmission structure to move horizontally through the movement of the screw in the sliding screw transmission structure, so that the nut structure moves horizontally by 1 mm;

[0058] (4) By installing a thrust cylindrical roller bearing above the nut structure, the thrust cylindrical roller bearing installed above the nut structure is connected to the rotating shaft of the dry gas sealing structure, so that the axial displacement S of the rotating shaft in the dry gas sealing structure is 1 mm;

[0059] (5) By installing non-contact displacement sensors on the spring seats in the dry gas sealing structure, a high-precision laser distance sensor is selected to measure the change in the length of the spring in the dry gas sealing structure, and the change in the length of the spring in the dry gas sealing structure △x1 is -1mm, and △x2 is 1mm;

[0060] (6) According to the measured length change △x of the spring and compared with the compressed length during installation, the spring stiffness Ks obtained during installation is 63.36N / mm. The real-time change of the spring force in the dry gas seal structure is calculated by the elastic Hooke's law, and the maximum change of the spring force △Fs1 and △Fs2 in the dry gas seal structure are 63.36N and 63.36N respectively;

[0061] (7) A bracket is installed at the other end of the rotating shaft, and a linear sliding bearing is installed in the bracket. The bracket is used to protect the rotating shaft for movement, and a tension pressure sensor is installed in the bracket on one side of the rotating shaft. The tension pressure sensor is used to measure the axial force exerted on the rotating shaft. The axial force Fn exerted on the rotating shaft in the dry gas sealing system is measured to be approximately 357.067N, and the actual maximum value is expected to be approximately 360N;

[0062] (8) The rotating shaft of the dry gas seal structure uses a linear sliding bearing to ensure that the rotating shaft can move axially stably. The linear sliding bearing will generate very small friction during operation. The dynamic friction force Ff1 of the linear sliding bearing is measured before installation;

[0063] (9) The friction force Ff1 of the linear sliding bearing calculated before installation is 1.958N by the spring force △Fs1, the spring force △Fs2, and the axial force Fn of the rotating shaft in the dry gas sealing system. The friction force Ff of the sealing ring in the dry gas sealing system is calculated to be about 114.1946N, and the actual maximum value of the friction force Ff of a single sealing ring in the dry gas sealing system is expected to be about 115N.

[0064] (10) A dry gas seal hysteresis curve is drawn using a computer based on the axial displacement S of the rotating shaft obtained by computer control, the calculated elastic force change △Fs2 of the spring Ⅱ20 in the dry gas seal structure, and the calculated friction force Ff of the sealing ring Ⅱ19 in the dry gas seal structure. In the dry gas seal hysteresis curve, the horizontal axis is represented by the axial displacement S of the rotating shaft in the dry gas seal structure, and the vertical axis is represented by the sum of the friction force Ff of the sealing ring Ⅱ19 in the dry gas seal structure and the elastic force △Fs2 of the spring Ⅱ20 in the dry gas seal structure.

[0065] Figure 5 Schematic diagram of the dry gas seal hysteresis curve obtained in this embodiment.

[0066] Embodiment 4: It is basically the same as Embodiment 3, except that: the axial movement of the rotating shaft in the dry gas sealing structure is controlled to be 2 mm; the change in the length of the spring in the dry gas sealing structure △x1 is -2 mm, and △x2 is 2 mm; the maximum change in the spring force △Fs1 in the dry gas sealing structure is obtained to be 126.72 N, and the maximum change in △Fs2 is 126.72 N; the axial force Fn exerted on the rotating shaft in the dry gas sealing system is measured to be approximately 483.7873 N, and the actual maximum value is expected to be approximately 485 N; the friction force Ff1 of the linear sliding bearing measured before installation is 1.958 N; the friction force Ff of the sealing ring in the dry gas sealing system is calculated to be approximately 114.1946 N, and the actual maximum value of the friction force Ff of a single sealing ring in the dry gas sealing system is expected to be approximately 115 N; Figure 6 Schematic diagram of the dry gas seal hysteresis curve obtained in this embodiment.

[0067] Embodiment 5: It is basically the same as Embodiment 3, except that: by introducing gas into the air inlet of the shell in the dry gas sealing structure, the pressure in the sealing cavity of the dry gas sealing structure is maintained at 1MPa; the axial movement of the rotating shaft in the dry gas sealing structure is controlled to be 2mm; the change in the length of the spring in the dry gas sealing structure △x1 is -2mm, and △x2 is 2mm; the maximum change in the spring force △Fs1 in the dry gas sealing structure is 126.72N, and the maximum change in △Fs2 is 126.72N; the axial force Fn exerted on the rotating shaft of the dry gas sealing system is measured to be approximately 390.534N, and the actual maximum value is expected to be approximately 392N; the friction force Ff1 of the linear sliding bearing measured before installation is 1.958N; the friction force Ff of the sealing ring in the dry gas sealing system is calculated to be approximately 67.568N, and the actual maximum value of the friction force Ff of a single sealing ring in the dry gas sealing system is expected to be approximately 70N; Figure 7 Schematic diagram of the dry gas seal hysteresis curve obtained in this embodiment.

[0068] The hysteresis curve diagram drawn by the present invention shows that the change of the closing force of the dry gas seal (the closing force is the sum of the back pressure, the spring force △Fs, and the sealing ring friction force Ff) is caused by the influence of the direction of the sealing ring friction force. It should be noted that since the back pressure of the dry gas seal static ring does not change, and the back pressure of the static ring is much greater than the spring force and the friction force, in order to better display the hysteresis curve, when drawing the curve, the closing force is reflected by deleting the back pressure.

[0069] In an ideal state (not affected by the friction of the sealing ring), the two lines should overlap, but due to the influence of the friction of the sealing ring, two curves will appear in the compression stage and the recovery stage. Therefore, it is shown that the dry gas seal hysteresis curve can be effectively obtained through the structure of the present invention, and the dry gas seal hysteresis curve can better observe the dry gas seal hysteresis phenomenon.

[0070] The specific implementation modes of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above implementation modes, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A method for testing hysteresis characteristics of dry gas seals, characterized in that: The test is carried out using a dry gas seal hysteresis characteristic test device, including: S1, by introducing gas into the air inlet of the housing (7) in the dry gas sealing structure, the pressure in the sealing cavity of the dry gas sealing structure is kept constant; S2, the power system (1) works to drive the rotating shaft (17) to move, and obtains the axial movement distance S of the rotating shaft (17); S3, measuring a distance change △x1 of the spring I (14) in the dry gas sealing structure (5) by using the distance sensor I (13), and measuring a distance change △x2 of the spring II (20) in the dry gas sealing structure (5) by using the distance sensor II (21); S4. Based on the measured length change △x of the spring and the spring stiffness Ks obtained during installation, the real-time change of the spring force in the dry gas seal structure is calculated by using the elastic Hooke's law, and the spring forces of spring I (14) and spring II (20) in the dry gas seal structure are recorded as △Fs1 and △Fs2 respectively; wherein △x is △x1 and △x2; S5, a tension and pressure sensor (25) is used to measure the axial force Fn exerted on the rotating shaft (17); S6, the friction force Ff of a single sealing ring in the dry gas seal structure is obtained by calculating the obtained elastic force △Fs1 of the spring I (14), the elastic force △Fs2 of the spring II (20), the axial force Fn exerted on the rotating shaft (17), and the friction force Ff1 between the rotating shaft (17) and the linear sliding bearing (22) measured in advance; S7, drawing a dry gas seal hysteresis curve diagram by using the obtained axial displacement S of the rotating shaft (17), the spring elastic force △Fs, and the sealing ring friction force Ff; The device for testing the hysteresis characteristics of dry gas seals comprises a power system (1), a sliding screw transmission structure, and a rotating shaft support (6); The sliding screw transmission structure comprises a screw rod (3) and a nut structure (4); the output end of the power system (1) is connected to one end of the screw rod (3), the nut structure (4) is mounted on the screw rod (3), one end of the rotating shaft (17) is fixed to the nut structure (4), and the rotating shaft (17) is supported by a rotating shaft bracket (6) so that the output movement of the power system (1) drives the rotating shaft (17) to perform linear movement along with the nut structure (4); A dry gas sealing structure (5) is mounted on the rotating shaft (17), and holes are opened on the housing (7) and the spring seat (8) in the dry gas sealing structure (5) for mounting a distance sensor I (13) and a distance sensor II (21), so that the distance sensor I (13) measures the distance change of the spring I (14) in the dry gas sealing structure (5), and the distance sensor II (21) measures the distance change of the spring II (20) in the dry gas sealing structure (5); One end of the rotating shaft (17) away from the nut structure (4) cooperates with a linear sliding bearing (22) installed in the bracket housing (23), and a tension pressure sensor (25) fixed on the bracket housing (23) is connected to the end of the rotating shaft (17) using a spring III (24).

2. The method for testing hysteresis characteristics of dry gas seal according to claim 1, characterized in that: The nut structure (4) is arranged in an upper and lower configuration, the lower portion of the nut structure (4) cooperates with the screw rod (3), and the upper portion of the nut structure (4) is provided with a thrust cylindrical roller bearing which cooperates with one end of the rotating shaft (17).

3. The method for testing hysteresis characteristics of dry gas seal according to claim 1, characterized in that: The axial force Fn exerted on the rotating shaft (17) is equal to △Fs1+△Fs2+2*Ff+Ff1.

4. The method for testing hysteresis characteristics of dry gas seal according to claim 1, characterized in that: The horizontal axis of the dry gas seal hysteresis curve represents the axial displacement S, and the vertical axis represents the sum of the spring force △Fs and the sealing ring friction force Ff; wherein the spring force △Fs and the sealing ring friction force Ff represent the elastic force of spring I (14) and the friction force of sealing ring I (15), or represent the elastic force of spring II (20) and the friction force of sealing ring II (19).

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