CA2031694C - Gas lubricated contact free sealing arrangement for a shaft - Google Patents
Gas lubricated contact free sealing arrangement for a shaftInfo
- Publication number
- CA2031694C CA2031694C CA002031694A CA2031694A CA2031694C CA 2031694 C CA2031694 C CA 2031694C CA 002031694 A CA002031694 A CA 002031694A CA 2031694 A CA2031694 A CA 2031694A CA 2031694 C CA2031694 C CA 2031694C
- Authority
- CA
- Canada
- Prior art keywords
- sealing
- sealing ring
- ring
- stationary
- gap
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16J—PISTONS; CYLINDERS; SEALINGS
- F16J15/00—Sealings
- F16J15/16—Sealings between relatively-moving surfaces
- F16J15/34—Sealings between relatively-moving surfaces with slip-ring pressed against a more or less radial face on one member
- F16J15/3404—Sealings between relatively-moving surfaces with slip-ring pressed against a more or less radial face on one member and characterised by parts or details relating to lubrication, cooling or venting of the seal
- F16J15/3408—Sealings between relatively-moving surfaces with slip-ring pressed against a more or less radial face on one member and characterised by parts or details relating to lubrication, cooling or venting of the seal at least one ring having an uneven slipping surface
- F16J15/3412—Sealings between relatively-moving surfaces with slip-ring pressed against a more or less radial face on one member and characterised by parts or details relating to lubrication, cooling or venting of the seal at least one ring having an uneven slipping surface with cavities
Abstract
A gas lubricated contact free sealing arrangement for a shaft, including a seal housing, a stationary sealing ring positioned in the seal housing, and a rotatable sealing ring mounted to and rigidly connected with the shaft. The two sealing rings work against each other at their sealing end surfaces with an intermediate lubricating gas. The stationary sealing ring is separated during operation and under a predetermined operating pressure difference from a cylindrical section of the seal housing located towards the shaft by a functional annular gap which is sealed by a sealing O-ring of rubber or plastic positioned in an annular groove, which stationary sealing ring is pressed against the lubricating gas with a pressure determined by at least one pressure spring. Both the rotatable sealing ring, and the stationary sealing ring are made of a hard sealing material, having a high heat conductivity, as well as a great modulus of elasticity and a high hardness. The stationary sealing ring has a surface inertia, which is so large that the gap width of the functional annular gap is practically equal, during operation and at an operating pressure difference, to the corresponding construction-dependent annular assembly gap between the stationary sealing ring and the cylindrical section of the seal housing during all operating conditions and is smaller than 0.4 mm, preferably smaller than 0.3 mm. The sealing O-ring is further constructed as a compensating and centering ring for the stationary sealing ring and, to this end, has a material hardness which is higher than the extrusion threshold of the material hardness at the given gap width and the predetermined operating pressure difference, and is smaller than a material hardness of 90 shore A in accordance with DIN 53 505. The gas lubricated sealing arrangement is especially suited as a high pressure seal with a long service life.
Description
~ 21~3~694 .
~ GAS LUBRICATED CONTACT FREE SEALING ARR~NGEMENT FOR A SHAFT
., The invention relates to gas lubricated, contact free sealing arrange~ents for a shaft having a seal housing, a stationary sealing ring located in the seal housing and a rotatable sealing ring mounted on and rigidly affixed to a rotatable shaft. The sealing rings work against each other at their sealing end surfaces while being separated by a seal gap, which is created by the lifti.ng force of a lubricating gas flowing between the sealing surfaces. The rotatable sealing ring is made of a material which has a high heat conductivity as well as a high modulus of elasticity and is of high hardness. The stationary sealing ring is separated by a functional gap from a cylindrical section of the seal housing which is located towards the shaft, during operation and at a predetermined operating pressure differential. The functional ~nn~llar gap is sealed through an O-ring, which is made of rubber or plastic and is positioned in an annular groove. The stationary sealing ring is pressed against the lifting force of the lubricating gas with a predetermined force provided by at least one pressure spring. In such a sealing arrAn~e -t one must differentiate between the functional annular gap described above and a construction dependent ~nn~ r asse~bly gap. The f~mctional annular gap develops out of the ~nmll~r assembly gap through a settling, in the assembled conditionj under the effect of a pressure difference which is sealed during operatio~. It is readily apparent t~at the re~in~er of the ' 25 construction oE such a gas lubricated contact free sealing ar~rangement, taking into consideration the special sealing functions, may be realized in accordance with constructions taught in the art and, especially, by using the corresponding methods, which have been developed on the sub~ect iTI engineerlng science since 1925.
Appropriate hard sealing materials are described, for example, in VDI-Zeitschrift, volume 102 (1960) number.l8, pages 728 to 732.
In a sealing arrangement known in the art as described, for example, in European Paeent EP 00 13 678, the sealing end surfaces are provided with recesses, which are constructed as spiral grooves that '~
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~ GAS LUBRICATED CONTACT FREE SEALING ARR~NGEMENT FOR A SHAFT
., The invention relates to gas lubricated, contact free sealing arrange~ents for a shaft having a seal housing, a stationary sealing ring located in the seal housing and a rotatable sealing ring mounted on and rigidly affixed to a rotatable shaft. The sealing rings work against each other at their sealing end surfaces while being separated by a seal gap, which is created by the lifti.ng force of a lubricating gas flowing between the sealing surfaces. The rotatable sealing ring is made of a material which has a high heat conductivity as well as a high modulus of elasticity and is of high hardness. The stationary sealing ring is separated by a functional gap from a cylindrical section of the seal housing which is located towards the shaft, during operation and at a predetermined operating pressure differential. The functional ~nn~llar gap is sealed through an O-ring, which is made of rubber or plastic and is positioned in an annular groove. The stationary sealing ring is pressed against the lifting force of the lubricating gas with a predetermined force provided by at least one pressure spring. In such a sealing arrAn~e -t one must differentiate between the functional annular gap described above and a construction dependent ~nn~ r asse~bly gap. The f~mctional annular gap develops out of the ~nmll~r assembly gap through a settling, in the assembled conditionj under the effect of a pressure difference which is sealed during operatio~. It is readily apparent t~at the re~in~er of the ' 25 construction oE such a gas lubricated contact free sealing ar~rangement, taking into consideration the special sealing functions, may be realized in accordance with constructions taught in the art and, especially, by using the corresponding methods, which have been developed on the sub~ect iTI engineerlng science since 1925.
Appropriate hard sealing materials are described, for example, in VDI-Zeitschrift, volume 102 (1960) number.l8, pages 728 to 732.
In a sealing arrangement known in the art as described, for example, in European Paeent EP 00 13 678, the sealing end surfaces are provided with recesses, which are constructed as spiral grooves that '~
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commence at at least one circumferential edge of the respective sealing ring end surface. Only ths rotatable sealing ring is made of a material which has a high heat conductivity as well as a great modulus of elasticity and hi~h hardness. Consequently, the stationary sealing ring is ~ade of a material, namely carbon, which has a comparatively small ~odulus of elasticity and a low hardness and which heat conductivity is not outstanding. No syecial importance is attached to the surface roughness and the pore volume of the sealing end surfaces. In this prior art sealing arrangement a distortion, a partial turning inside out of the stationary sealing ring, which is caused by the working temperature of the sealing arrangement, results from the relatively small modulus of elasticity and the low heat conductivity of the material of the stationary sealing ring. In fact, the temperature drop in axial direction is 25~C or more. Such a distortion of the stationary sealing ring would negatively influence the sealing conditions and the life of both sealing rings and, thus, the sealing arrangement, because of an unavoidable contact of the sealing surfaces during operation. Therefore, in the context of the generic measures known in the art, the positioning and construction of the sealing arrangement is selected so that the pressure distribution in the sealing gap (i.e. the lifting pressure of the gas in the gap) produces forces which counteract the distortion. In order to achieve this, it is absolutely required that the recesses a~e actively conveying spiral grooves, which produce a pumping effect and that the spiral grooves, which are included in at least the rotatable sealin~
ring, commence at one circumference of the sealing end surface only, and terminate at a dam or web of the sealing end surface, whereby certain numerical parameters must be met, with respect to the depth of the spiral grooves, the so-called width ratio of the webs and the desired equilibrium. However, even if these absolute requirements are met, the achieved effect is unsatisfactory. The desired equilibrium does not exist during all operating conditions. The plano-parallel positioning of the sealing end surfaces may only be restored to ro~; ~ol 1 y 70% through this resetting. All of this is based on the fact that the prior art measures do not take into consideration the :' ::
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commence at at least one circumferential edge of the respective sealing ring end surface. Only ths rotatable sealing ring is made of a material which has a high heat conductivity as well as a great modulus of elasticity and hi~h hardness. Consequently, the stationary sealing ring is ~ade of a material, namely carbon, which has a comparatively small ~odulus of elasticity and a low hardness and which heat conductivity is not outstanding. No syecial importance is attached to the surface roughness and the pore volume of the sealing end surfaces. In this prior art sealing arrangement a distortion, a partial turning inside out of the stationary sealing ring, which is caused by the working temperature of the sealing arrangement, results from the relatively small modulus of elasticity and the low heat conductivity of the material of the stationary sealing ring. In fact, the temperature drop in axial direction is 25~C or more. Such a distortion of the stationary sealing ring would negatively influence the sealing conditions and the life of both sealing rings and, thus, the sealing arrangement, because of an unavoidable contact of the sealing surfaces during operation. Therefore, in the context of the generic measures known in the art, the positioning and construction of the sealing arrangement is selected so that the pressure distribution in the sealing gap (i.e. the lifting pressure of the gas in the gap) produces forces which counteract the distortion. In order to achieve this, it is absolutely required that the recesses a~e actively conveying spiral grooves, which produce a pumping effect and that the spiral grooves, which are included in at least the rotatable sealin~
ring, commence at one circumference of the sealing end surface only, and terminate at a dam or web of the sealing end surface, whereby certain numerical parameters must be met, with respect to the depth of the spiral grooves, the so-called width ratio of the webs and the desired equilibrium. However, even if these absolute requirements are met, the achieved effect is unsatisfactory. The desired equilibrium does not exist during all operating conditions. The plano-parallel positioning of the sealing end surfaces may only be restored to ro~; ~ol 1 y 70% through this resetting. All of this is based on the fact that the prior art measures do not take into consideration the :' ::
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tribological characteristics of the seal (such a~ ~; supportable load, hardness, moment of friction), while the deficiencies which result therefrom cannot be suffici~ntly compensated through the attempt to reset the distortions of the st,qtionary seallng ring.
Furthermore, an 11nA~ceptably high leakage rate results in prior art constructions from the proble~s described above, which leakage rate increases on a large scale with increasing rotation speed of th~ shaft and, thus, the rotatable sealing ring, because of the pumping action of the spiral grooves, and is even more increased through the incomplete resetting.
The temperature and pressure difference dependent distortion of the stationary sealing ring which is accepted in the above described prior art construction and even provoked through the provision of a surface inertia of the stationary sealing ring, which deformation is supposed to be reset by the pressure distribution in the lubricating gas, has a further disturbing disadvantage: the above described distortion requires, in accordance with the laws of mechanics, that the Annl11Ar assembly gap must be substantially larger than the functional Ann1llAr gap, which i~ achie~ed when the stationary sealing ~- - ring is distorted, when the resetting of the distortion through the pressure distribution in the lubricating gas is not taken into consideration. This resetting is not important for the dimensioning of the Ann1l1Ar assembly gap and the ratio of the annular assembly gap to the ~unctional ~nn~llAr gap at different operating conditions of the sealing arrangement, since the temperature dependent deformation and resetting of the stationary sealing ring, which is dependent on the o~erating conditions of the sealing arrangèment, are not achieved simultaneously, while, on the other hand, a contact between the sealing end surfaces of the rotatablc sealing ring and the stationary sealing ring must be reliably prevented. The width of the construction dependent Anmll~r assembly gap is practically in the region of 0.4 or 0.5 mm for all common dia~eter ratios of sealing arrangements of the construction-described above. The width of the ~nn~ r gap must be covered by the 0-ring made of rubber or plastic ;
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even at the operating pressure difference, and especially when the final temperature distribution has not been achieved at the start-up of the operation, as well as when the desired resetting has been more or less completely achieved after the final adjustment of the temperature distribution. In prior art constructions, the O-ring ~ust therefore be constructed in such a way, with respect to the hardness of its material in Shore, that it may not be pressed into an annular gap, which corresponds in si~e to the ann~ r assembly gap of about 0.4 or 0.5 mm, by the generated operating pressure difference and is not prematurely destroyed by this, so-called, extrusion. Thus, in prior art constructions, the O-ring is selected to have a corresponding hardness. Its material hardness is generally at least 90 Shore A in accordance with DIN 53 505. Nevertheless, operating pressure differences of over 80 or r~ir~1 ly 100 bar ~re practically uncontrollable with prior art constructions, if the application requires the common lifetime of several thousand hours for the overall sealing arrangement. On the other hand, practice more frequently requires sealing arrangements in accordance with the principles of construction described above, which may be used for operating pressure differences w~ich are much above 100 ~ar. In addition, the function of the known overall sealing arr~ng~- t is adversely affected by an O-ring of high hardness in the annular gap between the stationary sealing ring and the cylindrical section of the seal housing. In - fact, in prior art sealing arrangements, the shaft with the rotatable sealing ring never rotates completely round and completely co-axial to the stationary sealing ring and ad~acent parts of the housing. This may result in vibrations which are transmitted into the stationary sealing ring. Therefore, a certain play must be allowed in the dimension of the functional Ann111Ar gap (independent of the size it reaches during operation), while a negative effect on the sealing action must be prevented. If an O-ring of high material hardness is used, it does not follow the induced vibrations of the stationary sealing ring and reduces the given play, which has a negative effect on the sealing action in the An~ r gap between the cylindrical section and the stationary sealing ring as well as in the gas 2~3~6~4 lubrication. Furthermore, this may lead to unwanted contacts between the sealing end surfaces of the rotatable sealing ring and the stationary sealing ring.
It i9 an ob~,ect oE this disclosure to provide a gas lubricated contact free sealing arrangement of the principle construction described above, which may be used for substantially higher pressures than prior art constructions, for example, for operating pressure differences of up to 300 bar or even up to 500 bar, while a good sealing action and a long lifetime is achieved.
i Accordingly, here described is a gas lubricated, contact free sealing arrangement for a shaft including a seal housing, a stationary sealing ring located in the seal housing, and a rotatable sealing ring mounted on and rigidly affixed to the shaft. The sealing rings act against each other with their sealing end surfaces at a sealing gap filled with a lubricating gas. The rotatable sealing ring is made of a material having a high heat conductivity, a great modulus of elasticity and a high hardness. The stationary sealing ring is separated under operating conditions and at a predetermined operat;ng pressure difference by a functional ~nn~ r g,ap from a cylindrical section of the seal housing located towards the shaft. The functional gap is sealed by an O~ring made of rubber or plastic. The stationary sealing ring is pressed against the lifting force of the lubricating gas at a force determined by at least one pressure spring. The stationary sealing ring is also made of a hard sealing material of high heat conductivity, great modulus of elasticity and high hardness. Specifically, the stationary sealing ring, as well as the rotatable sealing ring are made of a hard sealing material which has a heat conductivity of over 70 U/~K (~kJ/mhK), and a modulus of elasticity of over 25Q 000 N/mm2 at a corresponding hardness and a pore volume of less than 1% as well as a surface roughness of under 0.3 ~m (Ra), preferably 0.03 ym (Ra). The stationary sealing ring has such a large surface inertia that, in operation and at the operating pressure difference, the width of the functional annular gap between :
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the stationary sealing ring and the cylindrical section of the seal housing located towards the shaft is practically equal to the construction dependent width of the annular assembly gap between the cylindrical section and the stationary sealing ring and smaller than 0.4 mm, preEerably smaller than 0.3 mm. ~le sealing 0-ring is further used as a compensating and centering ring for the stationary sealing ring and, to this end, has a material hardness, which is higher than the extrusion threshold of the material hardness at the given gap width and the given operating pressure difference, and is smaller than a material hardness of 90 Shore A in accordance with DIN 53 505.
Preferably, the material hardness is smaller than 80 Shore A in accordance with the citsd standard. In other words, the positioning and construction of the sealing arrangement is so that the orientation of the sealing end surfaces of the rotatable sealing ring and the stationary sealing ring remains constant and preferably remains parallel at all times.
It is not necessary to take the production of any resetting forces into consideration for the construction of recesses whic~ are provided in at least one of the sealing end surfaces. Therefore, the recesses and the sealing end surfaces of the rotatable sealing ring and the stationary sealing ring may be constructed so that an optimal sealing action is achieved through the lubricating gas. To this end, ;; the recesse~ may be constructed as actively conveying spiral grooves.
However, in ~his context, it is also possible to construct the recesses as pressure effective recesses having a pressure edge.
With respect to gas dynamics, spiral grooves are elements, which effect a defined transport of gas. The transport may be used to counteract the leakage stream, which determines the leakage rate ~iscussed in the beg~ nni ne. In contrast, recesses which have a pressure edge are elements which counteract a defined transport of the gas and effect a pressure build-up. In both cases, the sealing action may be optimized and is not negatively affected by the requirement for : - . .: , :: .. . :~. ... , :
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t~e production of rssetting forces within speci.al e.quilibrium conditions.
In a preferred embodiment, the stationary sealing ring has a surface inertia which prevents a temperature dependent distortion of its sealing end surface. Such a surface inertia may be easily determined by the modern computer aided calculation methods of technlcal mechanics. "Ra'i defines the maan roughness value in accordance with DIN 4768. In a further preferred embodiment of the invention, the sealing end surfaces have an evenness of 0.4 micrometers per lOO mm diameter at room temperature and at a temperatura gradient of 0.
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With respect to the described requiremants in relation to heat conductivity, modulus of elasticity and hardness, the saaling rings may be made of diffarent materials. The sealing rings are prefarably made of a material selected from the group of tungsten carbide, silicon carbide, silicon/silicon carbide-compound, titanium carbide.
The sealing rings are manufactured, for example, through sintering or pressure sintering, whereby the pore volums may be ad~usted. Both sealing rings ~ay be made of the same material. However, the sealing rings can be made, with respect to the stationary sealing ring on one hand and the rotatable sealing ring on the other hand, of combinations of two of the above mentioned materials. In order to optimi~e the sealing arrangement, the sealing rings preferably have a pore volume of less than 0.5~. Tha stationary sealing ring preferably has a cross-section, which axial extent is at least twice its radial extent.
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In a preferred embodiment of a gas seal arrangement in accordance with the invention, which is preferred with respect to the construction of tha recesseC~ the recesses commence at one circumference of the sealing end surface and terminate at a dam of the sea~in~ end surface, which dam consists of a recess-free region of the sealing end surface. However, tha recesses may also commence at both the inner circumference and the outer circumference of the sealing end ~: :
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surfaces and terminate at a recess free median dam. In this case, the embodiment may be provided with spiral grooves in such a way that the pumping act;ons are counter directed. It is preferred, especially in an embodiment with pressure edges, that the. recesses terminate at a meandrical dam. The sealing end surfaces may be provided with an emergency glide finish. This may be, for example, a layer or coating of several micrometers made of graphite, polytetrafluoroethylene, or similar materials. The emergency glide finish may also be provided by carbon which is incorporated into the seal;ng ring material.
The embodiment which includes recesses with pressure edges is of special importance. In this contex~, a preferred embodiment of the ~ invention is characterized in that the pressure edges of the recesses ; e~tend in radial direction. However, the pressure edges may also be arcuate segments of recesses which are circular in plan view. In another embodiment o~ the invention, the pressure edges are constructed as lateral edges of recesses which are triangular in plan view and have one apex located at a circumference of the sealing end surface, which apex is cut off. It is pre~erred to construct the recesses in such a way that they are symmetrical in relation to a radially extending line. If this symmetry is achieved, a gas sealing arrangement in accordance with the invention is rotation direction independent. If this is not required or desired, the recesses may be constructed with unsymmetrical, for example, L-shaped, pressure edges. The depth Qf the recesses is in the micrometer range.
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The advantages achieved with the gas seal arrangement here described may be seen in that, the tribological characteristics are combined and the recesses constructed in such a way that the production of a momentum from the pressure distribution in the sealing gap for resetting the distortion, is no longer required. Recesses which produee a distinct pumping action may be omitted and are, in the embodiment with pressure edges, practically completely omitted, which substantially reduces the leakage rate. In comparison to a prior art generic gas seal arran~ement, the novel gas seal arrangement, . : ~ ., - ..
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g constructed for the same operating conditions, provides for a 50%
reduced leakage rate. This is partially due to the effect that although the sealing rings are heated during operation, they have such a small temperature gradient after the start up period and the subsequently resulting temperature equilibri.um that, even for this reason alon~, unwanted distortions will practically not appear. The temperature gradient in axial direction i9 below 1~C, while it is almost 20~C in the above described prior art constructions. This is true for all common parameters of the gas s0aling arrangement, and, for example, for a shaft diameter of 50 to 250 mm and a gliding speed of up to 150 m per second. For the rer~;n~er, the surface inertia of the stationary sealing ring prevents distort;ons thereof. In addition, the small pore volume and the small surface roughness in the region of the recesses provides for a further reduction of the leakage rate. Surprisingly, no start-up and shut-down problems have been observed. The latter is due to the fact that the annular assembly gap and the functional ~nn~ r gap between the stationary sealing ring and the associated cylindrical section of the housing have substantially the same width during all operating conditions. This width is so 20 ~;nir~l, that an O-ring can be used which has a very low material hardness, without the danger of extrusion of the O-ring into the :~ ~nn~ r gap, even at high operating pressure differences. Therefore, ~; the sealing arrangements described are especially suited as high pressure seals and have a longer service life.
Embodiments of the invention will now be further described by way of example only and with reference to the accompanying drawings, wherein Figure 1 shows a schematic illustration of half of an axial cross-section taken through an assembled sealing arrangement embodying with the invention;
Figure 2 is an end view of the rotatable sealing ring of the sealing arrangement shown in Figure l;
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Figures 3 to 7 are preferred embodiments of the rotatable sealing ring shown in Figure 2;
Figure 8 shows an enlarged section of Figure 1 lllustrating the mutual orientation of the sealing end surfaces of the stationary and the rotatable sealing ring as well as the sealing gap; and Figure 9 is an enlargement of the region o~ the functional sealing gap shown in Figuxe 1.
A sealing arrangement for a shaft as shown in Figures 1 to 9 includes, a sha~t 1, a seal housing 2, a stationary sealing ring 3 which is located in seal housing 2 and a rotatable sealing ring 4, which is mounted on and rigidly affixed to shaft 1. Sealing rings 3 and 4 move against each other with their respective sealing end surfaces 3a and 4a at a sealing gap 6, which is not visible in Figure 1 for reasons of scale. The sealing end surfacs 4a of rotatable sealing ring 4 is, in the preferred embodiment of the invention, provided with recesses 5 which are open to one circumference of the sealing end surface ~see Figs~ 2, 4, 5 and 6). The stationary sealing ring 3 acts in a direction towards the rotatable sealing ring 4 with a predetermined force which results from springs 7 distributed along the circumference of the stationary sealing ring 3, in t~is embodiment.
The stationary sealing ring 3 is axially movably supported and has a ring height 8 which is larger than the width of its sealing end surface 9.
The sealing rings 3 and 4 are made of a materlal which has a high heat conductivity, as well as a great modulus of elasticity, and a high hardness. Both sealing rlngs 3 and 4 have a small pore volume and a min;r~l surface roughness. The stationary sealing ring 3 is further provided with an axial surface inertia, whîch prevents heat distortions of its sealing end surface 3a. This is apparent from the cross-section shown in Figure 1. Turning now to Figures 2 and 3, ,,, . .:.: : ., . , :
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recesses 5 are constructed and positioned in such a way that the leakage rate is mini~i7ed, without taking into consideration the momentum resulting from the pressure distribution in thc sealing gap and counteracting the creation of distortions. The reduction of the leakage rate is achieved through pressure edges 5a, which counteract the pumping effect. The recesses 5, shown in Figures 2 and 3, are of a T-shape, and have radial pressure edges 5a. Recesses 5 are circular in Figure 4, and triangular in Figure 5, and have a similarly cut apex in both Figures. Sealing rings 3 and 4 are made of one material selected from the group of tungsten carbide, silicon carbide, silicon/silicon carbide-compound, titanium carbide, o~ combinations of two of these.
It is apparent, from Figures 2, 4 and 5, that recesses 5 commence at an outer circumference of sealing end surEace 4a, and terminate at a dam lO, which is formed by a recess-free region of sealing end surface 4a. In Figure 3, recesses 5 commence at the inner as well as the outer circumference of sealing end surface 4a and terminate at a median, recess-free dam lO. In Figure 3, dam lO has a substAntiAlly meandrical shape. Sealing end surfaces 3a and 4a may be provided with an emergency glide finish of small thickness made of graphite, polytetrafluoroethylene or similar materials, which is not illustrated, for reasons of scale. In the embodiment shown in Figures 6 and 7, recesses 5 are constructed as spiral grooves. The remainder of the construction is the same as in the embodiments shown in Figures 2 and 3.
Figure 8, which is an enlarged section of Figure l, illustrates that the two sealing end surfaces 3 and 4 are positioned very exactly plano-parallel to each other. In operation, they define a sealing gap D, which is a fixed gap. It is maintained by the lubricating gas. A
functional slnnt1l~r gap F is apparent in Figures l and 9. Functional stnn~1lstr gap F, which self-adjusts during operation, is equal to the construction-dependent annt1lStr assembly gap. Both are practically of the same gap width, The radial gap width is preferably equal to or .~
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smaller than 0.3 mm. The stationary sealing ring 3 is constructed to be distortion free, under all operating conditions. The enlarged section of Figure 1 shown in Figure 9, illustrates that the V-ring ll, even at high operating pressure differences, may not be pressed into the functional annular gap F, which has the aforesaid very small gap width, so that the O-ring may not be extruded into this functional ~nm~l~r gap F. Therefore, O-rlng ll may have a relatively low material hardness, so that the above described compensation and centering of tbe rotatable shaft and sealing ring com~ination is made possible. The elasticity of O-rings ll is advantageous for the mutual orientation of the sealing end surfaces. The pressure spring 7, shown in Figure l, may, for example, be constructed as a closed spring bellows, and may further be used as a centering element.
lS While the sealing end surfaces 4a and 3a of rotatable sealing ring 4, and stationary sealing ring 3 respectively, are positioned plano-parallel to each other in the embodiments shown in Figures 1 to 7, Figure 8, which is an enlarged section of Figure l, shows in broken lines an embodiment wherein the sealing end surface 3a of the statlonary sealing rlng 3 includes two AnnlllAr surfaces, in radial direction, which merge at an edge 12. In this embodiment, the annular surfaces are obliquely positioned to each other to form a ridge. They may also form a step at the location of t~e ridge.
The stationary sealing ring 3 may be constructed in such a way that it is not sub~ect to unwanted temperature-dependent distor-tions or other operation-dependent deformations. This provides for the ; realization of a very small annular assem-~bly gap, and a practically corresponding functional AnnlllAr gap F, which is small enough to allow the use of 0-rings which may not be extruded into the annular gap, which would prematurely destroy the O-ring, even at an operating pressure difference of 300 or even 500 bar. As a result, the new gas lubricated sealing arrangement is characterized in that it may be used for high and even very high pressures, at which it has a mini~
leakage rate, and a very long service life.
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. , . , ,. :., ,.. .. : ~, . .
Furthermore, an 11nA~ceptably high leakage rate results in prior art constructions from the proble~s described above, which leakage rate increases on a large scale with increasing rotation speed of th~ shaft and, thus, the rotatable sealing ring, because of the pumping action of the spiral grooves, and is even more increased through the incomplete resetting.
The temperature and pressure difference dependent distortion of the stationary sealing ring which is accepted in the above described prior art construction and even provoked through the provision of a surface inertia of the stationary sealing ring, which deformation is supposed to be reset by the pressure distribution in the lubricating gas, has a further disturbing disadvantage: the above described distortion requires, in accordance with the laws of mechanics, that the Annl11Ar assembly gap must be substantially larger than the functional Ann1llAr gap, which i~ achie~ed when the stationary sealing ~- - ring is distorted, when the resetting of the distortion through the pressure distribution in the lubricating gas is not taken into consideration. This resetting is not important for the dimensioning of the Ann1l1Ar assembly gap and the ratio of the annular assembly gap to the ~unctional ~nn~llAr gap at different operating conditions of the sealing arrangement, since the temperature dependent deformation and resetting of the stationary sealing ring, which is dependent on the o~erating conditions of the sealing arrangèment, are not achieved simultaneously, while, on the other hand, a contact between the sealing end surfaces of the rotatablc sealing ring and the stationary sealing ring must be reliably prevented. The width of the construction dependent Anmll~r assembly gap is practically in the region of 0.4 or 0.5 mm for all common dia~eter ratios of sealing arrangements of the construction-described above. The width of the ~nn~ r gap must be covered by the 0-ring made of rubber or plastic ;
;
:: : : .
"' :- .- . ~.:.. '' '',' ., :', :
6 9 ~
even at the operating pressure difference, and especially when the final temperature distribution has not been achieved at the start-up of the operation, as well as when the desired resetting has been more or less completely achieved after the final adjustment of the temperature distribution. In prior art constructions, the O-ring ~ust therefore be constructed in such a way, with respect to the hardness of its material in Shore, that it may not be pressed into an annular gap, which corresponds in si~e to the ann~ r assembly gap of about 0.4 or 0.5 mm, by the generated operating pressure difference and is not prematurely destroyed by this, so-called, extrusion. Thus, in prior art constructions, the O-ring is selected to have a corresponding hardness. Its material hardness is generally at least 90 Shore A in accordance with DIN 53 505. Nevertheless, operating pressure differences of over 80 or r~ir~1 ly 100 bar ~re practically uncontrollable with prior art constructions, if the application requires the common lifetime of several thousand hours for the overall sealing arrangement. On the other hand, practice more frequently requires sealing arrangements in accordance with the principles of construction described above, which may be used for operating pressure differences w~ich are much above 100 ~ar. In addition, the function of the known overall sealing arr~ng~- t is adversely affected by an O-ring of high hardness in the annular gap between the stationary sealing ring and the cylindrical section of the seal housing. In - fact, in prior art sealing arrangements, the shaft with the rotatable sealing ring never rotates completely round and completely co-axial to the stationary sealing ring and ad~acent parts of the housing. This may result in vibrations which are transmitted into the stationary sealing ring. Therefore, a certain play must be allowed in the dimension of the functional Ann111Ar gap (independent of the size it reaches during operation), while a negative effect on the sealing action must be prevented. If an O-ring of high material hardness is used, it does not follow the induced vibrations of the stationary sealing ring and reduces the given play, which has a negative effect on the sealing action in the An~ r gap between the cylindrical section and the stationary sealing ring as well as in the gas 2~3~6~4 lubrication. Furthermore, this may lead to unwanted contacts between the sealing end surfaces of the rotatable sealing ring and the stationary sealing ring.
It i9 an ob~,ect oE this disclosure to provide a gas lubricated contact free sealing arrangement of the principle construction described above, which may be used for substantially higher pressures than prior art constructions, for example, for operating pressure differences of up to 300 bar or even up to 500 bar, while a good sealing action and a long lifetime is achieved.
i Accordingly, here described is a gas lubricated, contact free sealing arrangement for a shaft including a seal housing, a stationary sealing ring located in the seal housing, and a rotatable sealing ring mounted on and rigidly affixed to the shaft. The sealing rings act against each other with their sealing end surfaces at a sealing gap filled with a lubricating gas. The rotatable sealing ring is made of a material having a high heat conductivity, a great modulus of elasticity and a high hardness. The stationary sealing ring is separated under operating conditions and at a predetermined operat;ng pressure difference by a functional ~nn~ r g,ap from a cylindrical section of the seal housing located towards the shaft. The functional gap is sealed by an O~ring made of rubber or plastic. The stationary sealing ring is pressed against the lifting force of the lubricating gas at a force determined by at least one pressure spring. The stationary sealing ring is also made of a hard sealing material of high heat conductivity, great modulus of elasticity and high hardness. Specifically, the stationary sealing ring, as well as the rotatable sealing ring are made of a hard sealing material which has a heat conductivity of over 70 U/~K (~kJ/mhK), and a modulus of elasticity of over 25Q 000 N/mm2 at a corresponding hardness and a pore volume of less than 1% as well as a surface roughness of under 0.3 ~m (Ra), preferably 0.03 ym (Ra). The stationary sealing ring has such a large surface inertia that, in operation and at the operating pressure difference, the width of the functional annular gap between :
, ~ ~'~' ~ ' ' ' ' ' ' 2~3~
the stationary sealing ring and the cylindrical section of the seal housing located towards the shaft is practically equal to the construction dependent width of the annular assembly gap between the cylindrical section and the stationary sealing ring and smaller than 0.4 mm, preEerably smaller than 0.3 mm. ~le sealing 0-ring is further used as a compensating and centering ring for the stationary sealing ring and, to this end, has a material hardness, which is higher than the extrusion threshold of the material hardness at the given gap width and the given operating pressure difference, and is smaller than a material hardness of 90 Shore A in accordance with DIN 53 505.
Preferably, the material hardness is smaller than 80 Shore A in accordance with the citsd standard. In other words, the positioning and construction of the sealing arrangement is so that the orientation of the sealing end surfaces of the rotatable sealing ring and the stationary sealing ring remains constant and preferably remains parallel at all times.
It is not necessary to take the production of any resetting forces into consideration for the construction of recesses whic~ are provided in at least one of the sealing end surfaces. Therefore, the recesses and the sealing end surfaces of the rotatable sealing ring and the stationary sealing ring may be constructed so that an optimal sealing action is achieved through the lubricating gas. To this end, ;; the recesse~ may be constructed as actively conveying spiral grooves.
However, in ~his context, it is also possible to construct the recesses as pressure effective recesses having a pressure edge.
With respect to gas dynamics, spiral grooves are elements, which effect a defined transport of gas. The transport may be used to counteract the leakage stream, which determines the leakage rate ~iscussed in the beg~ nni ne. In contrast, recesses which have a pressure edge are elements which counteract a defined transport of the gas and effect a pressure build-up. In both cases, the sealing action may be optimized and is not negatively affected by the requirement for : - . .: , :: .. . :~. ... , :
~ : : ::: : .: .
2~316~
t~e production of rssetting forces within speci.al e.quilibrium conditions.
In a preferred embodiment, the stationary sealing ring has a surface inertia which prevents a temperature dependent distortion of its sealing end surface. Such a surface inertia may be easily determined by the modern computer aided calculation methods of technlcal mechanics. "Ra'i defines the maan roughness value in accordance with DIN 4768. In a further preferred embodiment of the invention, the sealing end surfaces have an evenness of 0.4 micrometers per lOO mm diameter at room temperature and at a temperatura gradient of 0.
. ~
With respect to the described requiremants in relation to heat conductivity, modulus of elasticity and hardness, the saaling rings may be made of diffarent materials. The sealing rings are prefarably made of a material selected from the group of tungsten carbide, silicon carbide, silicon/silicon carbide-compound, titanium carbide.
The sealing rings are manufactured, for example, through sintering or pressure sintering, whereby the pore volums may be ad~usted. Both sealing rings ~ay be made of the same material. However, the sealing rings can be made, with respect to the stationary sealing ring on one hand and the rotatable sealing ring on the other hand, of combinations of two of the above mentioned materials. In order to optimi~e the sealing arrangement, the sealing rings preferably have a pore volume of less than 0.5~. Tha stationary sealing ring preferably has a cross-section, which axial extent is at least twice its radial extent.
~::
In a preferred embodiment of a gas seal arrangement in accordance with the invention, which is preferred with respect to the construction of tha recesseC~ the recesses commence at one circumference of the sealing end surface and terminate at a dam of the sea~in~ end surface, which dam consists of a recess-free region of the sealing end surface. However, tha recesses may also commence at both the inner circumference and the outer circumference of the sealing end ~: :
~ ~ ' ~: :
' 2~316~
surfaces and terminate at a recess free median dam. In this case, the embodiment may be provided with spiral grooves in such a way that the pumping act;ons are counter directed. It is preferred, especially in an embodiment with pressure edges, that the. recesses terminate at a meandrical dam. The sealing end surfaces may be provided with an emergency glide finish. This may be, for example, a layer or coating of several micrometers made of graphite, polytetrafluoroethylene, or similar materials. The emergency glide finish may also be provided by carbon which is incorporated into the seal;ng ring material.
The embodiment which includes recesses with pressure edges is of special importance. In this contex~, a preferred embodiment of the ~ invention is characterized in that the pressure edges of the recesses ; e~tend in radial direction. However, the pressure edges may also be arcuate segments of recesses which are circular in plan view. In another embodiment o~ the invention, the pressure edges are constructed as lateral edges of recesses which are triangular in plan view and have one apex located at a circumference of the sealing end surface, which apex is cut off. It is pre~erred to construct the recesses in such a way that they are symmetrical in relation to a radially extending line. If this symmetry is achieved, a gas sealing arrangement in accordance with the invention is rotation direction independent. If this is not required or desired, the recesses may be constructed with unsymmetrical, for example, L-shaped, pressure edges. The depth Qf the recesses is in the micrometer range.
, :
The advantages achieved with the gas seal arrangement here described may be seen in that, the tribological characteristics are combined and the recesses constructed in such a way that the production of a momentum from the pressure distribution in the sealing gap for resetting the distortion, is no longer required. Recesses which produee a distinct pumping action may be omitted and are, in the embodiment with pressure edges, practically completely omitted, which substantially reduces the leakage rate. In comparison to a prior art generic gas seal arran~ement, the novel gas seal arrangement, . : ~ ., - ..
:.... . .
:: , ~ ,: : , .., : : . . :: :: .
,~ ' ' :: ::: : ,: :.
: :~: , ~ - :. , : :~ : . :, 2 ~
g constructed for the same operating conditions, provides for a 50%
reduced leakage rate. This is partially due to the effect that although the sealing rings are heated during operation, they have such a small temperature gradient after the start up period and the subsequently resulting temperature equilibri.um that, even for this reason alon~, unwanted distortions will practically not appear. The temperature gradient in axial direction i9 below 1~C, while it is almost 20~C in the above described prior art constructions. This is true for all common parameters of the gas s0aling arrangement, and, for example, for a shaft diameter of 50 to 250 mm and a gliding speed of up to 150 m per second. For the rer~;n~er, the surface inertia of the stationary sealing ring prevents distort;ons thereof. In addition, the small pore volume and the small surface roughness in the region of the recesses provides for a further reduction of the leakage rate. Surprisingly, no start-up and shut-down problems have been observed. The latter is due to the fact that the annular assembly gap and the functional ~nn~ r gap between the stationary sealing ring and the associated cylindrical section of the housing have substantially the same width during all operating conditions. This width is so 20 ~;nir~l, that an O-ring can be used which has a very low material hardness, without the danger of extrusion of the O-ring into the :~ ~nn~ r gap, even at high operating pressure differences. Therefore, ~; the sealing arrangements described are especially suited as high pressure seals and have a longer service life.
Embodiments of the invention will now be further described by way of example only and with reference to the accompanying drawings, wherein Figure 1 shows a schematic illustration of half of an axial cross-section taken through an assembled sealing arrangement embodying with the invention;
Figure 2 is an end view of the rotatable sealing ring of the sealing arrangement shown in Figure l;
~' .
~' ... . . .~
2~3~
Figures 3 to 7 are preferred embodiments of the rotatable sealing ring shown in Figure 2;
Figure 8 shows an enlarged section of Figure 1 lllustrating the mutual orientation of the sealing end surfaces of the stationary and the rotatable sealing ring as well as the sealing gap; and Figure 9 is an enlargement of the region o~ the functional sealing gap shown in Figuxe 1.
A sealing arrangement for a shaft as shown in Figures 1 to 9 includes, a sha~t 1, a seal housing 2, a stationary sealing ring 3 which is located in seal housing 2 and a rotatable sealing ring 4, which is mounted on and rigidly affixed to shaft 1. Sealing rings 3 and 4 move against each other with their respective sealing end surfaces 3a and 4a at a sealing gap 6, which is not visible in Figure 1 for reasons of scale. The sealing end surfacs 4a of rotatable sealing ring 4 is, in the preferred embodiment of the invention, provided with recesses 5 which are open to one circumference of the sealing end surface ~see Figs~ 2, 4, 5 and 6). The stationary sealing ring 3 acts in a direction towards the rotatable sealing ring 4 with a predetermined force which results from springs 7 distributed along the circumference of the stationary sealing ring 3, in t~is embodiment.
The stationary sealing ring 3 is axially movably supported and has a ring height 8 which is larger than the width of its sealing end surface 9.
The sealing rings 3 and 4 are made of a materlal which has a high heat conductivity, as well as a great modulus of elasticity, and a high hardness. Both sealing rlngs 3 and 4 have a small pore volume and a min;r~l surface roughness. The stationary sealing ring 3 is further provided with an axial surface inertia, whîch prevents heat distortions of its sealing end surface 3a. This is apparent from the cross-section shown in Figure 1. Turning now to Figures 2 and 3, ,,, . .:.: : ., . , :
: . . : ;, ., :; . ,: , , - , . :
:~ . ; : ; ;,., : .. .,. , :
. :~ . . , . . ,: ,: . ., , :: .. .
,: : : : : : . . . ,,:.. . . , i:
: . ,, : - :: : ,: .. ,;: , : : .:, - . :
2 ~ 6 ~ ~
recesses 5 are constructed and positioned in such a way that the leakage rate is mini~i7ed, without taking into consideration the momentum resulting from the pressure distribution in thc sealing gap and counteracting the creation of distortions. The reduction of the leakage rate is achieved through pressure edges 5a, which counteract the pumping effect. The recesses 5, shown in Figures 2 and 3, are of a T-shape, and have radial pressure edges 5a. Recesses 5 are circular in Figure 4, and triangular in Figure 5, and have a similarly cut apex in both Figures. Sealing rings 3 and 4 are made of one material selected from the group of tungsten carbide, silicon carbide, silicon/silicon carbide-compound, titanium carbide, o~ combinations of two of these.
It is apparent, from Figures 2, 4 and 5, that recesses 5 commence at an outer circumference of sealing end surEace 4a, and terminate at a dam lO, which is formed by a recess-free region of sealing end surface 4a. In Figure 3, recesses 5 commence at the inner as well as the outer circumference of sealing end surface 4a and terminate at a median, recess-free dam lO. In Figure 3, dam lO has a substAntiAlly meandrical shape. Sealing end surfaces 3a and 4a may be provided with an emergency glide finish of small thickness made of graphite, polytetrafluoroethylene or similar materials, which is not illustrated, for reasons of scale. In the embodiment shown in Figures 6 and 7, recesses 5 are constructed as spiral grooves. The remainder of the construction is the same as in the embodiments shown in Figures 2 and 3.
Figure 8, which is an enlarged section of Figure l, illustrates that the two sealing end surfaces 3 and 4 are positioned very exactly plano-parallel to each other. In operation, they define a sealing gap D, which is a fixed gap. It is maintained by the lubricating gas. A
functional slnnt1l~r gap F is apparent in Figures l and 9. Functional stnn~1lstr gap F, which self-adjusts during operation, is equal to the construction-dependent annt1lStr assembly gap. Both are practically of the same gap width, The radial gap width is preferably equal to or .~
;
:. ~ : :
~3~69~
smaller than 0.3 mm. The stationary sealing ring 3 is constructed to be distortion free, under all operating conditions. The enlarged section of Figure 1 shown in Figure 9, illustrates that the V-ring ll, even at high operating pressure differences, may not be pressed into the functional annular gap F, which has the aforesaid very small gap width, so that the O-ring may not be extruded into this functional ~nm~l~r gap F. Therefore, O-rlng ll may have a relatively low material hardness, so that the above described compensation and centering of tbe rotatable shaft and sealing ring com~ination is made possible. The elasticity of O-rings ll is advantageous for the mutual orientation of the sealing end surfaces. The pressure spring 7, shown in Figure l, may, for example, be constructed as a closed spring bellows, and may further be used as a centering element.
lS While the sealing end surfaces 4a and 3a of rotatable sealing ring 4, and stationary sealing ring 3 respectively, are positioned plano-parallel to each other in the embodiments shown in Figures 1 to 7, Figure 8, which is an enlarged section of Figure l, shows in broken lines an embodiment wherein the sealing end surface 3a of the statlonary sealing rlng 3 includes two AnnlllAr surfaces, in radial direction, which merge at an edge 12. In this embodiment, the annular surfaces are obliquely positioned to each other to form a ridge. They may also form a step at the location of t~e ridge.
The stationary sealing ring 3 may be constructed in such a way that it is not sub~ect to unwanted temperature-dependent distor-tions or other operation-dependent deformations. This provides for the ; realization of a very small annular assem-~bly gap, and a practically corresponding functional AnnlllAr gap F, which is small enough to allow the use of 0-rings which may not be extruded into the annular gap, which would prematurely destroy the O-ring, even at an operating pressure difference of 300 or even 500 bar. As a result, the new gas lubricated sealing arrangement is characterized in that it may be used for high and even very high pressures, at which it has a mini~
leakage rate, and a very long service life.
' ' ' ' ' . " '1 ' , ' ."; , , ' ' 'I ' ., : , :: : :::: ~ :: : , , ::;
. , . , ,. :., ,.. .. : ~, . .
Claims (14)
1. A gas lubricated contact free sealing arrangement for a shaft, comprising:
a seal housing;
a stationary sealing ring located in the seal housing and a rotatable sealing ring mounted on and rigidly affixed to said shaft;
each said sealing ring having a sealing end surface, a gap formed between said sealing surfaces, and said sealing surfaces acting against one another through a lubricating gas in said gap, said stationary and said rotatable sealing rings being made of a material having a high heat conductivity, a high modulus of elasticity and a high hardness, said stationary sealing ring being separated, under operating conditions and at a predetermined operating pressure difference, by a functional annular gap from a cylindrical section of said seal housing located towards said shaft, said functional annular gap being sealed by an O-ring made of rubber or plastic, said stationary sealing ring being urged toward the rotatable sealing ring by at least one pressure spring, said seal being independent of shaft rotation direction, and recesses defined in at least one of the sealing rings in its sealing surface, each recess being symmetrical about a radial central line through said recess, said sealing rings being made of a hard sealing material having a heat conductivity of over 70 W/mK
(=kJ/mhK), a modulus of elasticity of over 250,000 N/mm2, a pore volume of less than 1%, and a surface roughness of less than 0.3 micrometers, said stationary sealing ring having a surface inertia, which is so large that gap width of said functional annular gap is equal to a construction-dependent gap width at all operating conditions, and is smaller than 0.4 mm, said sealing O-ring received in an open groove in the functional annular gap and being further constructed as a compensating and centering ring for said stationary sealing ring and having a material hardness which is larger than an extrusion threshold of the material hardness at said gap width and at said predetermined operating pressure difference, and is smaller than a material hardness of 90 shore A in accordance with DIN 53 505.
a seal housing;
a stationary sealing ring located in the seal housing and a rotatable sealing ring mounted on and rigidly affixed to said shaft;
each said sealing ring having a sealing end surface, a gap formed between said sealing surfaces, and said sealing surfaces acting against one another through a lubricating gas in said gap, said stationary and said rotatable sealing rings being made of a material having a high heat conductivity, a high modulus of elasticity and a high hardness, said stationary sealing ring being separated, under operating conditions and at a predetermined operating pressure difference, by a functional annular gap from a cylindrical section of said seal housing located towards said shaft, said functional annular gap being sealed by an O-ring made of rubber or plastic, said stationary sealing ring being urged toward the rotatable sealing ring by at least one pressure spring, said seal being independent of shaft rotation direction, and recesses defined in at least one of the sealing rings in its sealing surface, each recess being symmetrical about a radial central line through said recess, said sealing rings being made of a hard sealing material having a heat conductivity of over 70 W/mK
(=kJ/mhK), a modulus of elasticity of over 250,000 N/mm2, a pore volume of less than 1%, and a surface roughness of less than 0.3 micrometers, said stationary sealing ring having a surface inertia, which is so large that gap width of said functional annular gap is equal to a construction-dependent gap width at all operating conditions, and is smaller than 0.4 mm, said sealing O-ring received in an open groove in the functional annular gap and being further constructed as a compensating and centering ring for said stationary sealing ring and having a material hardness which is larger than an extrusion threshold of the material hardness at said gap width and at said predetermined operating pressure difference, and is smaller than a material hardness of 90 shore A in accordance with DIN 53 505.
2. A sealing arrangement as defined in claim 1, wherein said surface roughness is below 0.03 micrometers.
3. A sealing arrangement as defined in claim 1, wherein said gap width of said functional annular gap is smaller than 0.3 mm.
4. A sealing arrangement as defined in claim 1, wherein said material hardness of said O-ring is lower than 80 shore A.
5. A sealing arrangement as defined in claim 1, wherein said recesses are constructed as pressure-effective depressions, having a pressure edge.
6. A sealing arrangement as defined in claims 1 or 5, wherein said rotatable sealing ring and said stationary sealing ring are made of a material selected from the group of tungsten carbide, silicon carbide, silicon/silicon carbide-compound, titanium carbide, or two of such materials.
7. A sealing arrangement as defined in claim 6, wherein said sealing end surfaces of said stationary sealing ring and said rotatable sealing ring have an evenness of 0.4 micrometers per 100 mm diameter at room temperature in absence of any temperature gradient.
8. A sealing arrangement as defined in claim 7, wherein said stationary sealing ring and said rotatable sealing ring have a pore volume of less than 0.5%.
9. A sealing arrangement as defined in claim 8, wherein said stationary sealing ring has a ring cross-section having an axial extent which is at least double its radial extent.
10. A sealing arrangement as defined in claim 9, wherein said recesses commence at a circumference of said sealing end surface and terminate at a dam of said sealing end surface, said dam being located in a recess-free region of said sealing end surface.
11. A sealing arrangement as defined in claim 10, wherein said sealing end surface of said stationary sealing ring includes at least two annular surfaces in radial direction, which are connected through a ridge.
12. A sealing arrangement as defined in claim 11, wherein said sealing end surface of said stationary sealing ring includes two oblique annular surfaces in radial direction, which are connected with each other through one of a ridge and a step.
13. A sealing arrangement as defined in claim 12, wherein said sealing end surface of said stationary sealing ring is positioned at the same orientation relative to said sealing end surface of said rotatable sealing ring under all operating conditions.
14. A sealing arrangement as defined in claim 13, wherein said sealing end surface of said stationary sealing ring is positioned parallel to said sealing end surface of said rotatable sealing ring under all operating conditions.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3940258.4-12 | 1989-12-06 | ||
| DE19893940258 DE3940258A1 (en) | 1989-10-12 | 1989-12-06 | Gas tight seal for shaft and housing - has stator and rotor sealing ring with gap between |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2031694A1 CA2031694A1 (en) | 1991-06-07 |
| CA2031694C true CA2031694C (en) | 1999-04-06 |
Family
ID=6394870
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002031694A Expired - Lifetime CA2031694C (en) | 1989-12-06 | 1990-12-06 | Gas lubricated contact free sealing arrangement for a shaft |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0431505B1 (en) |
| JP (1) | JP2582940B2 (en) |
| AT (1) | ATE106999T1 (en) |
| CA (1) | CA2031694C (en) |
| DE (1) | DE59006034D1 (en) |
| NO (1) | NO905236L (en) |
Families Citing this family (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5071141A (en) * | 1990-07-17 | 1991-12-10 | John Crane Inc. | Spiral groove seal arrangement for high vapor-pressure liquids |
| US5492341A (en) * | 1990-07-17 | 1996-02-20 | John Crane Inc. | Non-contacting, gap-type seal having a ring with a patterned seal face |
| GB9103217D0 (en) * | 1991-02-15 | 1991-04-03 | Crane John Uk Ltd | Mechanical face seals |
| US5201531A (en) * | 1992-04-02 | 1993-04-13 | John Crane Inc. | Face seal with double spiral grooves |
| DE4409021A1 (en) * | 1994-03-16 | 1995-09-21 | Burgmann Dichtungswerk Feodor | Non-contact, gas-lubricated mechanical seal |
| DE9407733U1 (en) * | 1994-05-10 | 1994-07-07 | Burgmann Dichtungswerk Feodor | Sealing arrangement |
| GB9718846D0 (en) * | 1997-09-06 | 1997-11-12 | Crane John Uk Ltd | Mechanical face seals |
| DE10004263A1 (en) * | 2000-02-01 | 2001-08-02 | Leybold Vakuum Gmbh | Seal between stationary and rotating component in vacuum pump consists of blades arranged in herringbone pattern attached to each component |
| JP4606545B2 (en) * | 2000-05-02 | 2011-01-05 | イーグル工業株式会社 | Compressor shaft seal mechanism with mechanical seal |
| JP5352007B2 (en) * | 2010-06-23 | 2013-11-27 | 株式会社リケン | Seal ring |
| US9217430B2 (en) * | 2011-01-06 | 2015-12-22 | Eaton Corporation | Semi-plugged star gerotor and method of assembling the same |
| KR102276081B1 (en) * | 2017-01-30 | 2021-07-13 | 이구루코교 가부시기가이샤 | sliding parts |
| CN106938535B (en) * | 2017-05-09 | 2023-07-11 | 广东东晟密封科技有限公司 | Full-automatic smooth counter and use method thereof |
| DE102017209482A1 (en) * | 2017-06-06 | 2018-12-06 | Audi Ag | Ring for a mechanical seal |
| RU197821U1 (en) * | 2020-02-25 | 2020-06-01 | Федеральное государственное бюджетное образовательное учреждение высшего образования "Казанский государственный энергетический университет" | CONTACT DEVICE OF A VACUUM CIRCUIT BREAKER WITH ARREST-RESISTANT LININGS FROM ANISOTROPIC MATERIALS |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ES159807Y (en) * | 1968-01-15 | 1971-04-16 | Westinghouse Electric Corporation | A GASKET TO LIMIT FLUID FLOW ALONG A ROTATING SHAFT. |
| US4290613A (en) * | 1978-09-22 | 1981-09-22 | Associated Engineering Limited | Positive clearance radial face seals |
| GB2092242B (en) * | 1981-01-31 | 1984-12-19 | Rolls Royce | Non-contacting gas seal |
| JPH0222530Y2 (en) * | 1985-10-14 | 1990-06-18 | ||
| JPH0444941Y2 (en) * | 1986-03-13 | 1992-10-22 | ||
| CH677266A5 (en) * | 1986-10-28 | 1991-04-30 | Pacific Wietz Gmbh & Co Kg | |
| DE8628774U1 (en) * | 1986-10-28 | 1988-04-28 | Pacific Wietz Gmbh + Co Kg, 4600 Dortmund, De |
-
1990
- 1990-12-01 AT AT90123043T patent/ATE106999T1/en not_active IP Right Cessation
- 1990-12-01 EP EP90123043A patent/EP0431505B1/en not_active Expired - Lifetime
- 1990-12-01 DE DE59006034T patent/DE59006034D1/en not_active Expired - Fee Related
- 1990-12-04 NO NO90905236A patent/NO905236L/en unknown
- 1990-12-06 CA CA002031694A patent/CA2031694C/en not_active Expired - Lifetime
- 1990-12-06 JP JP2405363A patent/JP2582940B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH04272582A (en) | 1992-09-29 |
| JP2582940B2 (en) | 1997-02-19 |
| ATE106999T1 (en) | 1994-06-15 |
| NO905236D0 (en) | 1990-12-04 |
| CA2031694A1 (en) | 1991-06-07 |
| DE59006034D1 (en) | 1994-07-14 |
| EP0431505A1 (en) | 1991-06-12 |
| EP0431505B1 (en) | 1994-06-08 |
| NO905236L (en) | 1991-06-07 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed | ||
| MKEC | Expiry (correction) |
Effective date: 20121202 |