CN112556904A - Mechanical seal liquid film pressure monitoring device - Google Patents
Mechanical seal liquid film pressure monitoring device Download PDFInfo
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- CN112556904A CN112556904A CN202011417959.7A CN202011417959A CN112556904A CN 112556904 A CN112556904 A CN 112556904A CN 202011417959 A CN202011417959 A CN 202011417959A CN 112556904 A CN112556904 A CN 112556904A
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- 239000007788 liquid Substances 0.000 title claims abstract description 62
- 238000012806 monitoring device Methods 0.000 title claims abstract description 26
- 230000001681 protective effect Effects 0.000 claims description 32
- 230000003068 static effect Effects 0.000 claims description 12
- 238000003384 imaging method Methods 0.000 claims description 11
- 239000000463 material Substances 0.000 claims description 9
- 230000002829 reductive effect Effects 0.000 claims description 5
- 238000007789 sealing Methods 0.000 abstract description 25
- 238000012544 monitoring process Methods 0.000 abstract description 7
- 230000002159 abnormal effect Effects 0.000 abstract description 5
- 238000005259 measurement Methods 0.000 abstract description 4
- 238000009434 installation Methods 0.000 description 11
- 230000000694 effects Effects 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 4
- 230000003287 optical effect Effects 0.000 description 4
- 239000012530 fluid Substances 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 238000005299 abrasion Methods 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 230000001050 lubricating effect Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000005504 petroleum refining Methods 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- -1 polytetrafluoroethylene Polymers 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 230000008092 positive effect Effects 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/24—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
- G01L1/241—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet by photoelastic stress analysis
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- Investigating Or Analysing Materials By Optical Means (AREA)
- Measuring Fluid Pressure (AREA)
Abstract
The invention discloses a mechanical seal liquid film pressure monitoring device, which comprises: a monochromatic collimated light source which can emit monochromatic parallel light; the polarizer is used for forming the monochromatic parallel light emitted by the monochromatic collimation light source into polarized light; a first 1/4 wave plate for the polarized light to pass through and form a first circularly polarized light; a second 1/4 wave plate for eliminating a phase difference caused by the first 1/4 wave plate in the birefringent light and forming a second circularly polarized light; the analyzer is used for changing the propagation direction of the second circularly polarized light to form a photoelastic bar graph; and the stereoscopic microscope is used for amplifying the photoelastic bar graph. The invention can realize real-time and decomposed online monitoring and measurement of the liquid film pressure, the photoelastic stripe pattern can reflect the unidirectional pressure stress distribution and the liquid film pressure distribution of the sealing surface of the movable ring, and when the mechanical seal runs abnormally, the photoelastic stripe pattern can generate abnormal fluctuation, thereby effectively monitoring and preventing the occurrence of sealing failure accidents.
Description
Technical Field
The invention belongs to the technical field of pressure intensity detection, and particularly relates to a mechanical seal liquid film pressure intensity monitoring device.
Background
The liquid film seal is taken as a typical non-contact mechanical seal and is widely applied to rotating equipment under extreme working conditions of high speed, high temperature, heavy load and the like, such as petroleum refining devices, nuclear main pumps, shield machines, aircraft engines and the like. The miniature dynamic pressure groove formed on the contact end face generates a dynamic pressure effect, a stable and continuous liquid film is formed on the end face, the non-contact state of a friction pair is realized, the upstream pumping effect of the liquid film can achieve the sealing effect of zero leakage of a sealing medium, meanwhile, the friction wear and deformation of the contact face can be greatly reduced due to the existence of the liquid film, the service life of equipment is effectively prolonged, the operation period is effectively prolonged, and the sealing reliability is improved. The mechanical seal is used as a matched basic component, and the reliability and the stability of the mechanical seal have important influence significance on the running condition of equipment.
According to the analysis of the mechanical seal data in actual operation, the seal failure accident has the characteristics of emergencies and unpredictability, the seal failure develops very quickly, and once the seal failure happens, the accidents of production shutdown, environmental pollution and the like can bring about great economic loss. The abnormal increase of the liquid film thickness shown by the overhigh temperature of the end face of the sealing ring, the severe abrasion caused by the abnormal deformation of the end face and the increase of the leakage amount caused by the failure of accessories of the sealing system in common accidents can be reflected in real time from the liquid film pressure state. The pressure running state of the lubricating film on the sealing end face of the liquid film can be monitored, the whole running condition of the mechanical sealing system can be intuitively mastered in real time, and dynamic information of the pressure running state can play an important indicating role in judgment of the running condition of the mechanical sealing system and early warning of failure accidents, so that the sealing failure accidents are effectively prevented, and reliable running of unit equipment is guaranteed.
The above information disclosed in this background section is only for enhancement of understanding of the background of the application and therefore it may comprise prior art that does not constitute known to a person of ordinary skill in the art.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a mechanical seal liquid film pressure monitoring device, which can realize on-line monitoring and accurate measurement of liquid film pressure, effectively prevent sudden failure accidents of liquid film seal, improve the reliability of mechanical seal and reduce leakage fault loss.
In order to realize the purpose of the invention, the invention is realized by adopting the following technical scheme:
a mechanical seal liquid film pressure monitoring device is provided, wherein a mechanical seal is provided with a movable ring and a static ring which are matched, and a liquid film is formed between the movable ring and the static ring during the operation of the mechanical seal; the monitoring device includes:
a monochromatic collimated light source which can emit monochromatic parallel light;
the polarizer is used for forming the monochromatic parallel light emitted by the monochromatic collimation light source into polarized light;
a first 1/4 wave plate for the polarized light to pass through and form a first circularly polarized light;
the movable ring is made of transparent photoelastic materials capable of sending double refraction under a pressed state, and the first circularly polarized light forms double refraction light after passing through a contact area of the movable ring and the liquid film;
a second 1/4 wave plate for eliminating a phase difference caused by the first 1/4 wave plate in the birefringent light and forming a second circularly polarized light;
the analyzer is used for changing the propagation direction of the second circularly polarized light to form a photoelastic bar graph;
a stereomicroscope for magnifying the photoelastic bar graph;
and the imaging recorder is used for recording the amplified image of the stereoscopic microscope.
Further, the first 1/4 wave plate has a first fast axis and a first slow axis perpendicular to each other, and the second 1/4 wave plate has a second fast axis and a second slow axis perpendicular to each other, wherein the first fast axis and the second fast axis are vertically disposed.
Further, the single-color collimation light source further comprises an inner diameter side protection sleeve, the polarizer and the first 1/4 wave plate are fixedly arranged in the inner diameter side protection sleeve, and the single-color collimation light source is assembled at the first end, far away from the moving ring, of the inner diameter side protection sleeve.
Further, the one end that inside diameter side protective sleeve is close to the rotating ring is the second end, be equipped with in the inside diameter side protective sleeve and be used for fixing the second installation department of first 1/4 wave plates, be located the conical third chamber section between second installation department and the second end, the third chamber section is being close to the diameter reduces gradually in the direction of second end.
Further, the inner diameter side protection sleeve is adjacently arranged on the inner diameter sides of the static ring and the movable ring, the second end surrounds to form a light outlet, and an inner diameter side sheet is arranged in the light outlet.
Further, still be equipped with in the internal diameter side protective sleeve and be used for fixing the first installation department of polarizer, be located the first chamber section of toper between first end and the first installation department, first chamber section is keeping away from the diameter increases gradually in the direction of first end.
Further, a cylindrical second cavity section located between the first installation portion and the second installation portion is further arranged in the inner diameter side protection sleeve.
Further, still include outside diameter side protective sleeve, second 1/4 wave plate and analyzer set firmly in outside diameter side protective sleeve, the stereomicroscope assembly is in outside diameter side protective sleeve keeps away from the one end of rotating ring.
Further, the one end that outside diameter side protective sleeve is close to the rotating ring is the third end, be equipped with in the outside diameter side protective sleeve and be used for fixing the third installation department of second 1/4 wave plate, be located the conical fourth chamber section between third end and the third installation department, the diameter is gradually increased in the direction of keeping away from of fourth chamber section the third end.
Further, still be equipped with in the outside diameter side protective sleeve and fix the fourth installation department of analyzer, be located the fifth chamber section of cylinder between third installation department and the fourth installation department.
Further, a conical assembling portion for assembling the stereoscopic microscope and a cylindrical sixth cavity section located between the fourth installing portion and the assembling portion are further arranged in the outer diameter side protective sleeve.
Further, the third end is adjacently arranged on the outer diameter side of the static ring and the movable ring, the third end surrounds and forms a light inlet, and an outer diameter side sheet is arranged in the light inlet.
Further, the conversion formula of the pressure and the light intensity is as follows: p = n λ/fh, where n is the number of fringe levels of the optical fringe pattern, λ is the wavelength of light, f is the stress intensity coefficient corresponding to the moving ring of the photoelastic material, and h is the difference between the inner diameter and the outer diameter of the sealing ring.
Compared with the prior art, the invention has the advantages and positive effects that: based on the photoelastic principle that the movable ring generates refraction birefringence under the stress condition, the pressure distribution result of the liquid film is obtained by recording the stress photoelastic fringe pattern of the movable ring. Parallel light emitted by the monochromatic collimation light source forms polarized light after passing through the polarizing mirror, first circularly polarized light is formed after passing through a first 1/4 wave plate and irradiates a moving ring and a liquid film area, stress on the moving ring is different, refraction of the moving ring on the first circularly polarized light is different, phase difference is eliminated through a second 1/4 wave plate, the first circularly polarized light enters the analyzer, and finally the second circularly polarized light enters the stereomicroscope and is recorded by the imaging recorder. The invention can realize real-time and decomposed online monitoring and measurement of the liquid film pressure, the photoelastic stripe pattern can reflect the unidirectional pressure stress distribution and the liquid film pressure distribution of the sealing surface of the movable ring, and when the mechanical seal runs abnormally, the photoelastic stripe pattern can generate abnormal fluctuation, thereby effectively monitoring and preventing the occurrence of sealing failure accidents.
Other features and advantages of the present invention will become more apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a schematic structural diagram of an embodiment of a mechanical seal liquid film pressure monitoring device according to the present invention;
FIG. 2 is an enlarged schematic view of the monitoring device of FIG. 1;
FIG. 3 is an enlarged schematic view of a portion of the structure of FIG. 2;
fig. 4 is an enlarged schematic view of the inner diameter side protective sleeve of fig. 2;
fig. 5 is an enlarged schematic view of the outer diameter side protective sleeve of fig. 2;
fig. 6 is a schematic view of a radial cross-section of the monitoring device of fig. 1.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention.
In the description of the present invention, it should be noted that the terms "upper", "lower", "left", "right", and the like indicate orientations or positional relationships based on the positional relationships shown in the drawings, and the directions near the mechanical seal axis are "inner" and vice versa. The terminology is for the purpose of describing the invention only and is for the purpose of simplifying the description, and is not intended to indicate or imply that the device or element so referred to must be in a particular orientation, constructed and operated, and is not to be considered limiting of the invention. Moreover, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance; the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
Referring to fig. 1-6, which are views showing an embodiment of a liquid film pressure monitoring device for a mechanical seal according to the present invention, the mechanical seal includes a rotating ring 10, a stationary ring 20, and a liquid film 30 formed by dynamic pressure effect, a micro dynamic pressure groove is formed on the surface of the rotating ring 10, the rotating ring 10 and a rotating shaft 40 are connected to the rotating shaft 40 through a shaft sleeve 50 and rotate with the rotating shaft 40 at a certain rotation speed, and a spring 60 provides a pressing force for the rotating ring 10 to ensure the attachment of the rotating ring and the stationary disc. The shaft sleeve 50, the movable ring 10, the sealing static ring 20 and the end cover 70 form a sealing cavity together. When the mechanical seal is operated, the movable ring 20 rotates along with the rotating shaft 40, and the liquid mold 80 with the thickness of micron order is generated between the movable ring 10 and the stationary ring 20 through the dynamic pressure effect generated by the micro-grooves formed on the surface of the movable ring 10.
Referring to fig. 2, in order to detect the pressure of the liquid film 80, a monitoring device 90 is provided, including: a monochromatic collimation light source 91, a polarizer 92, a first 1/4 wave plate 93, a second 1/4 wave plate 94, an analyzer 95, a stereomicroscope 9,6 and an imaging recorder 97; the monochromatic collimated light source 91 can emit monochromatic parallel light, the polarizer 92 is used for forming the monochromatic parallel light emitted by the monochromatic collimated light source 91 into polarized light, and the first 1/4 wave plate 93 is used for enabling the polarized light to pass through and forming first circularly polarized light; the movable ring 10 is made of transparent photoelastic materials capable of sending double refraction under a pressed state, and first circularly polarized light forms double refraction light through the movable ring 10; the second 1/4 wave plate 94 is used to eliminate a phase difference caused by the first 1/4 wave plate 93 in the birefringent light and form a second circularly polarized light; the analyzer 95 is configured to change the propagation direction of the second circularly polarized light to form a photoelastic bar graph, the stereoscopic microscope 96 is configured to amplify the photoelastic bar graph, and the imaging recorder 97 is configured to record an image amplified by the stereoscopic microscope.
The photoelastic material object can generate different refraction phenomena under different stresses, the monochromatic collimated light source 91 irradiates from the inner diameter side to the outer diameter side of the movable ring 20, and the movable ring 20 is made of transparent photosensitive material; based on the photoelastic principle that the movable ring 10 generates refraction birefringence under stress, the pressure distribution result of the liquid film 80 is obtained by recording the stress photoelastic fringe pattern of the movable ring 10, and the thickness of the liquid film 80 is extremely small compared with the movable ring. The parallel light emitted by the monochromatic collimation light source 91 forms polarized light after passing through the polarizer 92, forms first circularly polarized light after passing through the first 1/4 wave plate 93, and irradiates the movable ring 10 and the liquid film 80 area, the stress on the movable ring 10 is different, and the refraction of the movable ring 10 to the first circularly polarized light is different; the phase difference is then removed by a second 1/4 wave plate 94 and enters an analyzer 95, and finally enters a stereo microscope 96 and is recorded by an image recorder 97. The invention can realize real-time and decomposed online monitoring and measurement of the pressure of the liquid film 80, the photoelastic stripe pattern can reflect the unidirectional pressure stress distribution of the sealing surface of the movable ring 10 and the pressure distribution of the liquid film 80, and when the mechanical seal runs abnormally, the photoelastic stripe pattern can generate abnormal fluctuation, thereby effectively monitoring and preventing the occurrence of sealing failure accidents.
The monitoring device 90 is arranged along the radial direction of the static ring 20, wherein the monochromatic light collimation light source 91 is fixed on the static ring 20, the stereoscopic microscope 96 and the imaging recorder 97 are fixed on the end cover 70, and the axes of all components in the monitoring device 90 are overlapped.
When the mechanical seal works, a liquid medium enters the seal cavity, the moving ring 10 rotates along with the rotating shaft 40, and liquid enters the micro dynamic pressure groove of the moving ring 10 and is gradually pumped into a space between the moving ring 10 and the static ring 20 to form a stable liquid film 80 under the action of a dynamic pressure effect. The monochromatic collimation light source 91 emits parallel light, the parallel light enters the polarizer 92 to form polarized light, the polarized light enters the first 1/4 wave plate 93 to form first circularly polarized light, the first circularly polarized light passes through the contact area of the moving ring 10 and the liquid film 80, and the moving ring 10 irradiated by the first circularly polarized light generates birefringence under different pressure stress applied by the liquid film 80; then the phase difference caused by the first 1/4 wave plate 93 is eliminated by the birefringent light through the second 1/4 wave plate 94, a photoelastic stripe image with light and dark phases is formed after the birefringent light passes through the analyzer 95, the photoelastic stripe image is recorded by the imaging recorder 97 after being amplified by the stereoscopic microscope 96, the imaging recorder 97 is connected with a computer, and the stress condition of the movable ring 10 and the pressure distribution of the liquid film 80 can be obtained after calculation and conversion of the photoelastic stripe. When the mechanical seal normally works, due to the characteristic that the movable ring 10 rotates along with the rotating shaft 40 to operate, the photoelastic stripe pattern is regularly and periodically changed, the pressure of the liquid film 80 is dynamically and stably distributed, once the mechanical seal is degraded due to high temperature, high pressure and other factors, the thickness of the liquid film is suddenly changed, the pressure fluctuation of the pressed film is intensified visually, the irregular violent fluctuation change of the stripes of the photoelastic stripe pattern is reflected, the pressure change of the liquid film 80 is monitored on line in real time, the failure of the whole sealing system caused by the performance degradation development is effectively avoided, and accidents such as medium leakage pollution and the like are prevented.
On the light path, monochromatic parallel light emitted by the monochromatic light collimation light source 91 is natural light, and the polarizer 92 changes the parallel light into polarized light; the first 1/4 wave plate 93 changes polarized light into first circularly polarized light, and the fast axis F1 and the slow axis S1 of the first 1/4 wave plate 93 are perpendicular to each other; the included angle between the first 1/4 wave plate 93 and the polarization direction of the analyzer 95 is 45 degrees; the movable ring 10 is preferably made of transparent photoelastic material epoxy resin, and can ensure the first circularly polarized light beam to pass through; the second 1/4 wave plate 94 is used to eliminate the phase difference of the 3 light beams caused by the first 1/4 wave plate 93, and the fast axis F2 and the slow axis S2 of the second 1/4 wave plate 94 are perpendicular to each other; the fast and slow axes of the first 1/4 wave plate 93 and the second 1/4 wave plate 94 are perpendicular to each other, i.e., F1 is perpendicular to F2, and S1 is perpendicular to S2; by changing the direction of the second circularly polarized light, the analyzer 95 vibrates the light beam in a plane n after passing through the analyzer 95, and the polarizer 13 vibrates the polarized light in a direction m, where m is perpendicular to n. The light beam presents a photoelastic stripe pattern after passing through the analyzer 95, is recorded by the imaging recorder 97 after being amplified by the stereomicroscope 96, and is transmitted into a computer for calibration and conversion to obtain a pressure stress result of the contact area.
Referring to fig. 2 and 4, to prevent the sealed fluid from entering the optical path and interfering, the monitoring device 90 further includes an inner diameter side protection sleeve 98 and an outer diameter side protection sleeve 99, the polarizer 92 and the first 1/4 wave plate 93 are fixed inside the inner diameter side protection sleeve 98, and the monochromatic collimated light source 91 is mounted on the first end 981 of the inner diameter side protection sleeve 98 far away from the movable ring 10. The inner diameter side protection sleeve 99 has a second end 987 at one end thereof close to the movable ring 10, a second mounting portion 985 for fixing the first 1/4 wave plate 93, a first mounting portion 953 for fixing the polarizer 95, a tapered third cavity section 986 between the second mounting portion 983 and the second end 987, a tapered first cavity section 982 between the first end 981 and the first mounting portion 983, and a cylindrical second cavity section 984 between the first mounting portion 983 and the second mounting portion 985 are disposed in the inner diameter side protection sleeve 98, the diameter of the third cavity section 986 is gradually reduced in a direction close to the second end 987, and the diameter of the first cavity section 982 is gradually increased in a direction away from the first end 981. By providing the first and second mounting portions 983 and 985 for fixing the polarizer 92 and the first 1/4 wave plate 93 in the inner diameter side protection sleeve 98, and providing the first, second and third cavity segments 982, 984 and 986 in the transmission shape of the light beam, it is advantageous to ensure the transmission of the light beam and avoid reducing the interference of other light beams.
The inner diameter side protective sleeve 98 is adjacently arranged on the inner diameter side of the static ring 20 and the moving ring 10, the second end 987 surrounds to form a light outlet 988, the light outlet 988 is in contact with the moving ring 10 and the liquid film 80, in order to prevent the fluid of the liquid film 80 from entering the light outlet 988 to cause test errors to the optical path, an inner diameter side sheet 989 is arranged in the light outlet 988, and the inner diameter side sheet 989 is a circular transparent sheet. The thickness of the liquid film 50 and the depth of the dynamic pressure grooves are both in the order of micrometers, and the inner diameter side thin plate 98 has a diameter of 20 micrometers and a thickness of 10 micrometers, and its influence on the propagation of light is negligible because the size of the transparent thin plate is extremely thin compared to other geometric components.
Referring to fig. 5, a second 1/4 wave plate 93 and an analyzer 95 are fixed inside an outer diameter side protective sleeve 99, and a stereomicroscope 96 is fitted to an end of the outer diameter side protective sleeve 99 remote from the movable ring 10. One end of the outer diameter side protection sleeve 99 close to the movable ring 10 is a third end 991, a third mounting part 993 for fixing a second 1/4 wave plate 94, a tapered fourth cavity section 992 positioned between the third end 991 and the third mounting part 993, a fourth mounting part 995 for fixing the analyzer 95 and a cylindrical fifth cavity section 994 positioned between the third mounting part 993 and the fourth mounting part 995 are arranged in the outer diameter side protection sleeve 99, and the diameter of the fourth cavity section 995 is gradually increased in the direction far away from the third end 991; also provided in the outer diameter side protection sleeve 99 are a tapered fitting portion 997 for fitting the stereomicroscope 96, and a cylindrical sixth cavity section 996 between the fourth mounting portion 995 and the fitting portion 997.
The outer diameter side protective sleeve 99 is adjacently arranged on the outer diameter side of the static ring 20 and the moving ring 10, the third end 991 surrounds to form a light inlet 998, the light inlet 998 is in contact with the moving ring 10 and the liquid film 80, in order to prevent the fluid of the liquid film 80 from entering the light inlet 998 to cause test errors to a light path, an outer diameter side sheet 999 is arranged in the light inlet 998, and the outer diameter side sheet 999 is a circular transparent sheet.
The inner diameter side protection sleeve 98 and the outer diameter side protection sleeve 99 are preferably made of polytetrafluoroethylene materials, have certain elasticity, and are in arc-shaped design in the contact area with the movable ring 10, so that the sealed liquid is prevented from entering a light path to cause interference, friction between the movable ring 4 and the protection sleeves is reduced to the maximum extent, and friction and abrasion are reduced as much as possible on the basis of ensuring the sealing fit. The inner diameter side protective sleeve 98, the monochromatic collimation light source probe 91, the outer diameter side protective sleeve 99 and the stereomicroscope 97 are fixedly connected through conical structures, and sealing performance is guaranteed.
The thickness of the liquid film 80 is micron-sized, the geometric dimension of the liquid film is negligible compared with other components, and the distribution of the pressure stress applied to the sealing moving ring 4 can be equivalent to the pressure distribution of the liquid film. The polarized light beam passes through the contact area of the liquid film of the sealing movable ring, the passing liquid film and the area are limited, the thickness of the combined liquid film 10 is extremely small, and the measured area of the liquid film can be regarded as line contact.
Because the polarized light vibration directions of the polarizer 92 and the analyzer 95 are perpendicular, light cannot pass through the polarizer, and a photoelastic fringe pattern with alternate light and dark colors is presented on the analyzer 95, and is calibrated and converted by a computer after being recorded by the imaging recorder 97, so that a pressure distribution result of the liquid film 80 is obtained. The calculation formula of the pressure and light stripe test result is as follows: p = n λ/fh, where n is the number of fringe levels of the optical fringe pattern, λ is the wavelength of light, f is the stress intensity coefficient corresponding to the moving ring of the photoelastic material, and h is the difference between the inner diameter and the outer diameter of the sealing ring.
The stereomicroscope 96 is amplified and then enters the imaging recorder 97 to be connected with a computer, the photoelastic fringe pattern result is input into the computer, the distribution condition of the pressure stress of the liquid film 80 relative to the movable ring 10 is obtained through analysis and conversion of the photoelastic fringe pattern, and the change of the photoelastic fringe pattern is monitored to monitor and master the operation condition of the mechanical seal.
To ensure that sufficient liquid enters the sealing interface of the rotating ring 10 and the stationary ring 20 and to provide sufficient dynamic pressure to form a liquid film 80 with a certain stiffness, the rotating ring 10 is formed with a groove on the outer diameter side, preferably a spiral groove.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions.
Claims (10)
1. A mechanical seal liquid film pressure monitoring device is provided, wherein a mechanical seal is provided with a movable ring and a static ring which are matched, and a liquid film is formed between the movable ring and the static ring during the operation of the mechanical seal; characterized in that, the monitoring device includes:
a monochromatic collimated light source which can emit monochromatic parallel light;
the polarizer is used for forming the monochromatic parallel light emitted by the monochromatic collimation light source into polarized light;
a first 1/4 wave plate for the polarized light to pass through and form a first circularly polarized light;
the movable ring is made of transparent photoelastic materials capable of sending double refraction under a pressed state, and the first circularly polarized light forms double refraction light after passing through a contact area of the movable ring and the liquid film;
a second 1/4 wave plate for eliminating a phase difference caused by the first 1/4 wave plate in the birefringent light and forming a second circularly polarized light;
the analyzer is used for changing the propagation direction of the second circularly polarized light to form a photoelastic bar graph;
a stereomicroscope for magnifying the photoelastic bar graph;
and the imaging recorder is used for recording the amplified image of the stereoscopic microscope.
2. The monitoring device of claim 1, wherein the first 1/4 wave plate has first fast and slow axes that are orthogonal to each other, and the second 1/4 wave plate has second fast and slow axes that are orthogonal to each other, the first fast and slow axes being vertically disposed.
3. The monitoring device of claim 1, further comprising an inner diameter side protective sleeve, wherein the polarizer and the first 1/4 wave plate are secured within the inner diameter side protective sleeve, and wherein the monochromatic collimated light source is mounted at a first end of the inner diameter side protective sleeve distal from the movable ring.
4. The monitoring device of claim 3, wherein one end of the inner diameter side protective sleeve near the movable ring is a second end, a second mounting portion for fixing the first 1/4 wave plate and a tapered third cavity section located between the second mounting portion and the second end are arranged in the inner diameter side protective sleeve, and the diameter of the third cavity section is gradually reduced in a direction near the second end.
5. The monitoring device of claim 4, wherein the inner diameter side protective sleeve is disposed adjacent to inner diameter sides of the stationary and moving rings, the second end surrounding a light exit port in which an inner diameter side tab is disposed.
6. The monitoring device of claim 4, wherein a first mounting portion for fixing the polarizer is further provided in the inner diameter side protective sleeve, and a first tapered cavity section is provided between the first end and the first mounting portion, and the first cavity section has a diameter gradually increasing in a direction away from the first end.
7. The monitoring device of claim 6, wherein a second cylindrical cavity section is further disposed within the inner diameter side protective sleeve between the first and second mounting portions.
8. The monitoring device of any one of claims 1 to 7, further comprising an outer diameter side protective sleeve, wherein the second 1/4 wave plate and the analyzer are fixedly arranged in the outer diameter side protective sleeve, and wherein the stereomicroscope is assembled at an end of the outer diameter side protective sleeve away from the movable ring.
9. The monitoring device of claim 8, wherein an end of the outer diameter side protective sleeve near the movable ring is a third end, a third mounting portion for fixing the second 1/4 wave plate and a tapered fourth cavity section between the third end and the third mounting portion are arranged in the outer diameter side protective sleeve, and the diameter of the fourth cavity section gradually increases in a direction away from the third end.
10. The monitoring device of claim 8, wherein a tapered fitting portion for fitting the stereomicroscope, a fourth fitting portion for fixing the analyzer, and a cylindrical sixth cavity section between the fourth fitting portion and the fitting portion are further provided in the outer diameter side protective sleeve.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
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