- Email: [email protected]
Patents in 2003 – what did they cover?
PATENTS REVIEW • •
Hot air for 168 hours at 160°C; and Saturated steam for 168 hours at 185°C.
Results of the three point bending tests Figure 7 present the results of the flexibility test using the two types of conditioning. As a measurement, the deflection of the test specimen expressed in percentage area is shown. The multi-layer structure exhibits the highest deflection at break when conditioned in both steam and hot air. Steam hammer often occurs in steam applications, and leads to damage of the sealing materials. A more flexible gasket, which endures a deflection without breaking, will therefore contribute to a more reliable flange connection.
Hot compression The deformation of a gasket under load is dependent on two material-specific factors: • •
The type and quantity of reinforcing raw materials. Network structures of the elastomer.
As samples 1–4 contain the same fibres and fillers in the same quantity, the differences in the deformation behaviour can be attributed to the influence of the rubber matrix. To quantify the influence of the less dense network of the special elastomer, all gaskets were submitted to a gasket load of 50 MPa and the temperature was raised from room temperature to 300°C with a temperature rise of 10°C per minute. Two minutes after this final temperature was reached, the thickness decrease was measured (Figure 8).
Results of the hot compression test Figure 9 shows that the measured thickness decreases in relation to the original thickness after cold compression. The greatest thickness decrease is clearly exhibited by the gasket bound only with the special elastomers. This gasket suffers the highest deformation, because of the extremely low number of cross-links within the rubber network . The increased creep of the gasket in an application results in a reduction of the gasket pressure in rigid flange connections. In this case, the multi-layer material also performs well. Because the structure contains layers with special elastomers, this will naturally lead to an increase in deformation, but the middle layer – with its dense network structure – limits the increase in deformation to an acceptable value.
Conclusions In the field of compressed fibre materials there is considerable potential to improve product performance through the use of new types of raw materials. As an example, the use of special elastomers in sealing materials significantly improves the property profile at elevated temperatures. The new material concept described in this article significantly increases ageing resistance at elevated temperatures when compared to conventional gasket materials. Using this methodology, all of the undesirable property changes associated with conventional gaskets – such as embrittlement, formation of crevices and increased leakage – can be significantly reduced. Longer service life and increased temperature resistance can be achieved by application of special elastomers in separate layers within a multi-layer sealing structure.
The first commercial material based on this concept is being marketed as Klinger top-sil-ML1.
References 1. H. Sächtling and K. Oberbach, KunststoffTaschenbuch (Hanser Verlag, 1998). 2. F. Röthnmeyer and F. Sommer, Kautschuktechnologie (Hanser Verlag, Munich, Germany, 2001). 3. High performance technical rubber goods. Technical Information, Bayer Rubber Business Group. 4. K. Stoekhert and W. Woebcken, Kunststofflexikon (Hanser Verlag, 1973). 5. ISTAG Test Protocol. Contact: Rich. Klinger Dichtungstechnik GmbH & Co KG, Am Kanal 8–10, A-2352 Gumpoldskirchen, Austria. Tel: +43 2252 62599 137, Fax: +43 2252 62599 296, Email: [email protected], Web: www.klinger.co.at Or contact: ISTAG AG, Research & Development Center of the Klinger Group, Industrie Nord, Seonerstrasse 287, CH-5704 Egliswil, Switzerland. Tel. +41 62 769 3061, Fax +41 62 769 3063, Email: [email protected], Web: www.klingergroup.com
This feature article is based on a paper first presented at the XIII Dichtungskolloquium: Investigations and Application of Sealing Elements, University of Münster, Germany on 21 September 2003. This paper is published in ‘Untersuchung und Anwendung von Dichtelementen’ (Vulkan-Verlag, Essen, Germany, 2003; ISBN 3-8027-2201-9).
Patents in 2003 – what did they cover? Bob Flitney, Contributing Editor From the more than a million patents published in 2003, 190 were selected for abstract review in Sealing Technology. What sealing topics did these cover? A review of the subject areas can illustrate where there is the most interest from the user industries, and also which are the most competitive.
Introduction To begin a review, the first obvious step is to divide the subjects into some broad categories. Even after merging a number of categories, the list below demonstrates the wide range of applications and types of seal that are part of the modern world. It is easy to concentrate on fairly obvious subjects such as mechanical seals, gaskets or bearing seals. However, a review of the subject areas listed, in which the Editor has selected the categories, reminds us that sealing technology is far from being a narrow and specialized subject, but covers a very wide range of applications. Our industry spreads as far as the telephone, calculator
Sealing Technology March 2004
and keyboard on this desk and the fast food cartons that are used in vast numbers. The patents featured in Sealing Technology from 2003, which have appeared in issues from March 2003 to this edition, have included the following broad categories: Gaskets
16 (8.4%)
Mechanical seals
15 (7.9%)
Valves
15 (7.9%)
Miscellaneous
14 (7.4%)
Electronic equipment
14 (7.4%)
Oil & gas, downhole, wellhead and pipeline seals
14 (7.4%)
Closures, packaging and food Window and door seals Bearing and other lip seals Battery seals Pipe fittings Turbine clearance seals Medical and pharmaceutical Cable joints Oil well piping screw connection joints Elastomer materials Magnetic seals High-pressure specific seals Filter bodies Piston rings Stirling engine Reciprocating seals
13 12 11 9 9 8 6 6
(6.8%) (6.3%) (5.8%) (4.7%) (4.7%) (4.2%) (3.2%) (3.2%)
5 4 4 4 3 3 3
(2.6%) (2.1%) (2.1%) (2.1%) (1.6%) (1.6%) (1.6%)
2 (1.1%)
11
PATENTS REVIEW Deciding which patents to include in the newsletter can be difficult. There are many that are on the fringe of potential interest. Often the subject area is not one that directly concerns our regular readers, but potentially useful or stimulating ideas may be included. I would welcome your views on the range of patents that we have covered. One area where there is still room for expanding our coverage is in the field of medical patents that involve sealing. It is instructive to first look at the application areas rather than the individual sealing specialities. Three user groups dominate the applications: automotive, electrical/electronics, and the oil & gas industry. This is probably not surprising, as the first two dominate the volume of manufactured components, and oil & gas provides many of the most arduous operating environments where improved reliability is a major concern.
one of those technologies that would be widely adopted if a satisfactory seal could be developed.
Electrical and electronic The electrical and electronic topics covered by sealing patents have been quite varied, but have often been for high-integrity seals. The largest single category has been dry cell battery seals, for which there were nine. A feature of several was the inclusion of some form of venting in the event of excess pressure in the cell. The number of these patents reflects a high volume and competitive industry requiring high seal integrity that is also featured by all of the products looking similar. The manufacturers are therefore going to considerable efforts to improve and differentiate their product from the competition.
Automotive
Oil and gas
The automotive patents are primarily in three categories: gaskets, bearing seals and door seals. In our group of 16 gasket patents, nine were on cylinder head gaskets. A number were concerned with increasing the sealing contact stress around the top of the cylinder bores, such as WO 03/104687 in this issue. Others were on improved materials, but also of particular interest were two that involved introducing instrumentation within the gasket to measure the engine operating conditions, such as WO 03/071167 in the November issue – a reminder of just how sophisticated the modern vehicle has become. The automotive bearing seals were often concerned with assembly methods, and three were specifically for water pump bearings. The assembly of the current designs of bearing seal with a multiplicity of excluder lips appears to be an area of concern. The window and door seals are interesting in that these now have extremely complex profiles, with a number of sealing lips. These appear to be designed to provide a good integrity of sealing with low closing force and against a body surface, rather than the machined surfaces that would be considered normal for many other applications. Some interesting methods to increase the sealing force without a corresponding increase in closing force have been featured. These include the stiffening of the seal by a piezoceramic actuator, covered in WO 03/104008 this month, and magnetic inserts in WO 03/064197 in the October issue. The automotive sector is also well represented in the valve category. Six of the 15 were for reciprocating engines or compressors. It is interesting to note that there is still activity aimed at providing an internal combustion engine with rotary valves. This appears to be
The oil & gas industry also has many products that look superficially very similar to each other and with a very competitive supplier base. This is reflected in the number of patent applications. In addition to those categorized directly as seals, we have included five oil well casing pipe joint seals. There were in fact more than this, but I have concentrated on those that have some direct sealing interest, such as the inclusion of a seal insert within the thread. Something that was rather different in this category was two patents for sealing the joints of composite risers, WO 03/050379 and 050380 in the August issue. The various wellhead and annulus seals that have featured include both metal and polymer seals. The metal seals have often included some means of increasing the contact stress to improve the seal, or in some instances a soft insert for this purpose. An example of this is WO 03/071170 (November). Other well head seals include elastomeric designs that have been specifically developed to function at low temperatures, and two are included this month, WO 03/095873 and 095874 on page 13. This has been a problem area that has often been overlooked with the highly fluid resistant elastomers required for many oil-well applications, as discussed in the Editor’s Comments last month.
12
Closures After the above three application areas, closures, packaging and food provide the next most numerous area of patents. These can be quite varied, and many foil and film closure methods have not been included. However, others are more directly related to sealing technology, and can provide an interesting insight into both the detail and requirements of what is again a very high volume industry. The sealing and
retention of a drinking straw in WO 03/059777 (September) is an example.
Individual seal types If we look at specific seal types, the mechanical seal patents were not aligned to any particular degree with a specific industry. Three were concerned with gas seal developments, but – perhaps reflecting a mature and well developed technology – quite a number of the rest were concerned with manufacturing methods rather than novel designs. Seal component related patents have the manufacture of seals from wear-resistant materials or coatings, and also anti-rotation device design. Another was concerned with a providing a seal during maintenance on mixers (WO 03/064898, October). In February there was a very complicated seal arrangement for the rotary joints on a diving suit, WO 03/097443. An interesting feature of this seal is that it is designed to fail-safe to isolate the interior of the diving suit if the face seal fails. Although no further movement is possible once it has assumed the fail-safe condition, this idea could have applications for hazardous process conditions. A close competitor to gas mechanical seals, in some applications, are the various forms of turbine clearance seal. Eight patents were covered dealing with these during the year, mainly in the currently popular area of brush seals. One patent describing the background technology was covered in detail in April 2003 (US 6505835), and provides a useful introduction if required. As we have seen, the largest number of gasket patents was concerned with internal combustion engine cylinder heads. The next most prolific area for gaskets was in an area that may be considered a future competitor to the cylinder head gasket: fuel cells. Fuel cells will require a large number of seals, and it is interesting that some of these patents describe manufacturing and assembly in addition to the gasket itself. Those valve seals that were not concerned with reciprocating machinery were primarily valve seats for several different types of process valve. Some were subtle and simple designs to improve valve sealing performance, such as the revised seat seal geometry in WO 03/098081 this month. Others appear to have quite complex designs to increase seating stress, such as WO 03/089820 (February). Outside the automotive industry the window and door seals were primarily concerned with buildings, or in one case ducts within a building. Several were seals for smoke-stop doors. A similarity with the automotive seals is the complexity of the shapes that are patented as the designer endeavours to provide an adequate seal with minimum sealing force on surfaces that are not necessarily well aligned or even. The majority of bearing and other lip seals came within the automotive area. Others were primarily concerned with the manufacture of PTFE seals.
Sealing Technology March 2004
PATENTS The numerous pipefitting designs cover a very wide range, and in most cases these were quite specific to a type of application. Some appear to be quite complex with a considerable number of components; WO 03/100309 provides an example in this issue. Magnetic seals have been around for probably 30 years, and efforts to extend their appeal continue. The patents this year have been divided between those concerned with configurations for particular applications, either feed-through or disc drives, WO 03/087636 (last month) and others with the seal design. This month, WO 03/104689 describes the geometry of the magnetic poles on the stator, but in WO 03/016755 (April) an arrangement is described that is also able to cope with axial shaft movement.
The piston ring patents have primarily been concerned with the design of the joint to provide a benefit in particular circumstances. A further example of a technology searching for a sealing solution to make it more commercially viable is the Stirling cycle machine, and during the year three patents described features of the displacer unit.
Conclusions Providing the patent abstracts is an interesting, if slightly time-consuming, part of the editing this newsletter. If the patents are in a topic area that I know well it is gratifying to see developments continuing.
Since becoming Editor I have adopted the policy of trying to provide a brief overview of the patent subject, and also the reasoning behind the application. As a user this is how I would like to use this section; the idea is that readers will be able to scan the section for subjects of interest to themselves and, if particularly interested for either technical or commercial reasons, then look into the patent itself. And, as an engineer writing for engineers, I have decided that a picture is worth a thousand words and introduced rather more illustrations and less text. I would appreciate your comments on both the style and the content of the Patents section. And if sometimes there does not seem to be much information, it may be because there is only a 50word abstract in English for me to use.
Patents Metal end cap seal with pressure trap Applicant: Cooper Cameron Corporation, USA A metal end cap seal for a similar duty to WO/095872. In this design the inner diameter of the resilient ring has one or more circumferential cavities open to the inner diameter, that are connected to the outer diameter by radial holes. After the seal is energized, a high pressure is applied to the seal so that the pressure will migrate past the nose of the seal, through the radial holes, and into the groove. The groove is shaped so that, once the high pressure is relieved, the pressure within the groove will become trapped. This trapped pressure acts as a source of stored energy, to increase the energization of the seal. The purpose is to enable the seal to function more effectively at low temperatures. Patent number: WO 03/095873
Inventors: K.E. Keene and D.K. Wolff Publication date: November 2003
Sealing Technology March 2004
Applicant: Polymer Sealing Solutions Ltd, UK This patent is particularly concerned with the static sealing of truck wheel bearing hubs. A seal has a reinforcing insert (7) and a resilient projection (5). It is arranged to be a snap-fit within an annular recess formed within a bearing. The bearing has a retention lip (15) adjacent to the recess, against which the resilient lip of the seal abuts and resists removal. Patent number: WO 03/095856
Inventors: D.M. Williamson and G. Sturman Publication date: 20 November 2003
The snap fit seal for truck bearings described in WO 03/095856.
Method of influencing the rigidity of a vehicle door window seal The metal end cap seal with additional pressurization groove, in WO 03/095873.
Metal end cap seal with annular protrusions Applicant: Cooper Cameron Corporation, USA A further design of metal end cap seal designed to improve sealing at an increased range of temperatures. The seal generally has a resilient ring with a metal end cap on each end. The inner diameter of the resilient ring has one or more annular protrusions along the inside diameter of the resilient
Static seal between bearing ring and shaft
ring. The annular protrusions are sized to provide additional interference with the internal tubular member and provide areas of localized compressive stress within the resilient ring, while maintaining a desirable overall stress distribution. Patent number: WO 03/095874 Inventors: K.E. Keene et al. Publication date: 20 November 2003
Applicant: Metzeler Automotive Profile Systems GmbH, Germany In this patent an elastomer seal (20) is fitted to a frame (40) and closed against a window (30). It may have one or several sealing lips (22) that rest against the window. To improve the sealing system and obtain a variable sealing effect, that is adapted to environmental factors, the sealing lips are provided with a piezo-ceramic actuator (50) and can be pressed against the window using a voltage applied to the actuator. Patent number: WO 03/104008 Inventor: C. Huck Publication date: 18 December 2003
Vehicle window door seal from WO 03/104008, with piezoceramic actuators to increase the sealing force.
13
Hot air for 168 hours at 160°C; and Saturated steam for 168 hours at 185°C.
Results of the three point bending tests Figure 7 present the results of the flexibility test using the two types of conditioning. As a measurement, the deflection of the test specimen expressed in percentage area is shown. The multi-layer structure exhibits the highest deflection at break when conditioned in both steam and hot air. Steam hammer often occurs in steam applications, and leads to damage of the sealing materials. A more flexible gasket, which endures a deflection without breaking, will therefore contribute to a more reliable flange connection.
Hot compression The deformation of a gasket under load is dependent on two material-specific factors: • •
The type and quantity of reinforcing raw materials. Network structures of the elastomer.
As samples 1–4 contain the same fibres and fillers in the same quantity, the differences in the deformation behaviour can be attributed to the influence of the rubber matrix. To quantify the influence of the less dense network of the special elastomer, all gaskets were submitted to a gasket load of 50 MPa and the temperature was raised from room temperature to 300°C with a temperature rise of 10°C per minute. Two minutes after this final temperature was reached, the thickness decrease was measured (Figure 8).
Results of the hot compression test Figure 9 shows that the measured thickness decreases in relation to the original thickness after cold compression. The greatest thickness decrease is clearly exhibited by the gasket bound only with the special elastomers. This gasket suffers the highest deformation, because of the extremely low number of cross-links within the rubber network . The increased creep of the gasket in an application results in a reduction of the gasket pressure in rigid flange connections. In this case, the multi-layer material also performs well. Because the structure contains layers with special elastomers, this will naturally lead to an increase in deformation, but the middle layer – with its dense network structure – limits the increase in deformation to an acceptable value.
Conclusions In the field of compressed fibre materials there is considerable potential to improve product performance through the use of new types of raw materials. As an example, the use of special elastomers in sealing materials significantly improves the property profile at elevated temperatures. The new material concept described in this article significantly increases ageing resistance at elevated temperatures when compared to conventional gasket materials. Using this methodology, all of the undesirable property changes associated with conventional gaskets – such as embrittlement, formation of crevices and increased leakage – can be significantly reduced. Longer service life and increased temperature resistance can be achieved by application of special elastomers in separate layers within a multi-layer sealing structure.
The first commercial material based on this concept is being marketed as Klinger top-sil-ML1.
References 1. H. Sächtling and K. Oberbach, KunststoffTaschenbuch (Hanser Verlag, 1998). 2. F. Röthnmeyer and F. Sommer, Kautschuktechnologie (Hanser Verlag, Munich, Germany, 2001). 3. High performance technical rubber goods. Technical Information, Bayer Rubber Business Group. 4. K. Stoekhert and W. Woebcken, Kunststofflexikon (Hanser Verlag, 1973). 5. ISTAG Test Protocol. Contact: Rich. Klinger Dichtungstechnik GmbH & Co KG, Am Kanal 8–10, A-2352 Gumpoldskirchen, Austria. Tel: +43 2252 62599 137, Fax: +43 2252 62599 296, Email: [email protected], Web: www.klinger.co.at Or contact: ISTAG AG, Research & Development Center of the Klinger Group, Industrie Nord, Seonerstrasse 287, CH-5704 Egliswil, Switzerland. Tel. +41 62 769 3061, Fax +41 62 769 3063, Email: [email protected], Web: www.klingergroup.com
This feature article is based on a paper first presented at the XIII Dichtungskolloquium: Investigations and Application of Sealing Elements, University of Münster, Germany on 21 September 2003. This paper is published in ‘Untersuchung und Anwendung von Dichtelementen’ (Vulkan-Verlag, Essen, Germany, 2003; ISBN 3-8027-2201-9).
Patents in 2003 – what did they cover? Bob Flitney, Contributing Editor From the more than a million patents published in 2003, 190 were selected for abstract review in Sealing Technology. What sealing topics did these cover? A review of the subject areas can illustrate where there is the most interest from the user industries, and also which are the most competitive.
Introduction To begin a review, the first obvious step is to divide the subjects into some broad categories. Even after merging a number of categories, the list below demonstrates the wide range of applications and types of seal that are part of the modern world. It is easy to concentrate on fairly obvious subjects such as mechanical seals, gaskets or bearing seals. However, a review of the subject areas listed, in which the Editor has selected the categories, reminds us that sealing technology is far from being a narrow and specialized subject, but covers a very wide range of applications. Our industry spreads as far as the telephone, calculator
Sealing Technology March 2004
and keyboard on this desk and the fast food cartons that are used in vast numbers. The patents featured in Sealing Technology from 2003, which have appeared in issues from March 2003 to this edition, have included the following broad categories: Gaskets
16 (8.4%)
Mechanical seals
15 (7.9%)
Valves
15 (7.9%)
Miscellaneous
14 (7.4%)
Electronic equipment
14 (7.4%)
Oil & gas, downhole, wellhead and pipeline seals
14 (7.4%)
Closures, packaging and food Window and door seals Bearing and other lip seals Battery seals Pipe fittings Turbine clearance seals Medical and pharmaceutical Cable joints Oil well piping screw connection joints Elastomer materials Magnetic seals High-pressure specific seals Filter bodies Piston rings Stirling engine Reciprocating seals
13 12 11 9 9 8 6 6
(6.8%) (6.3%) (5.8%) (4.7%) (4.7%) (4.2%) (3.2%) (3.2%)
5 4 4 4 3 3 3
(2.6%) (2.1%) (2.1%) (2.1%) (1.6%) (1.6%) (1.6%)
2 (1.1%)
11
PATENTS REVIEW Deciding which patents to include in the newsletter can be difficult. There are many that are on the fringe of potential interest. Often the subject area is not one that directly concerns our regular readers, but potentially useful or stimulating ideas may be included. I would welcome your views on the range of patents that we have covered. One area where there is still room for expanding our coverage is in the field of medical patents that involve sealing. It is instructive to first look at the application areas rather than the individual sealing specialities. Three user groups dominate the applications: automotive, electrical/electronics, and the oil & gas industry. This is probably not surprising, as the first two dominate the volume of manufactured components, and oil & gas provides many of the most arduous operating environments where improved reliability is a major concern.
one of those technologies that would be widely adopted if a satisfactory seal could be developed.
Electrical and electronic The electrical and electronic topics covered by sealing patents have been quite varied, but have often been for high-integrity seals. The largest single category has been dry cell battery seals, for which there were nine. A feature of several was the inclusion of some form of venting in the event of excess pressure in the cell. The number of these patents reflects a high volume and competitive industry requiring high seal integrity that is also featured by all of the products looking similar. The manufacturers are therefore going to considerable efforts to improve and differentiate their product from the competition.
Automotive
Oil and gas
The automotive patents are primarily in three categories: gaskets, bearing seals and door seals. In our group of 16 gasket patents, nine were on cylinder head gaskets. A number were concerned with increasing the sealing contact stress around the top of the cylinder bores, such as WO 03/104687 in this issue. Others were on improved materials, but also of particular interest were two that involved introducing instrumentation within the gasket to measure the engine operating conditions, such as WO 03/071167 in the November issue – a reminder of just how sophisticated the modern vehicle has become. The automotive bearing seals were often concerned with assembly methods, and three were specifically for water pump bearings. The assembly of the current designs of bearing seal with a multiplicity of excluder lips appears to be an area of concern. The window and door seals are interesting in that these now have extremely complex profiles, with a number of sealing lips. These appear to be designed to provide a good integrity of sealing with low closing force and against a body surface, rather than the machined surfaces that would be considered normal for many other applications. Some interesting methods to increase the sealing force without a corresponding increase in closing force have been featured. These include the stiffening of the seal by a piezoceramic actuator, covered in WO 03/104008 this month, and magnetic inserts in WO 03/064197 in the October issue. The automotive sector is also well represented in the valve category. Six of the 15 were for reciprocating engines or compressors. It is interesting to note that there is still activity aimed at providing an internal combustion engine with rotary valves. This appears to be
The oil & gas industry also has many products that look superficially very similar to each other and with a very competitive supplier base. This is reflected in the number of patent applications. In addition to those categorized directly as seals, we have included five oil well casing pipe joint seals. There were in fact more than this, but I have concentrated on those that have some direct sealing interest, such as the inclusion of a seal insert within the thread. Something that was rather different in this category was two patents for sealing the joints of composite risers, WO 03/050379 and 050380 in the August issue. The various wellhead and annulus seals that have featured include both metal and polymer seals. The metal seals have often included some means of increasing the contact stress to improve the seal, or in some instances a soft insert for this purpose. An example of this is WO 03/071170 (November). Other well head seals include elastomeric designs that have been specifically developed to function at low temperatures, and two are included this month, WO 03/095873 and 095874 on page 13. This has been a problem area that has often been overlooked with the highly fluid resistant elastomers required for many oil-well applications, as discussed in the Editor’s Comments last month.
12
Closures After the above three application areas, closures, packaging and food provide the next most numerous area of patents. These can be quite varied, and many foil and film closure methods have not been included. However, others are more directly related to sealing technology, and can provide an interesting insight into both the detail and requirements of what is again a very high volume industry. The sealing and
retention of a drinking straw in WO 03/059777 (September) is an example.
Individual seal types If we look at specific seal types, the mechanical seal patents were not aligned to any particular degree with a specific industry. Three were concerned with gas seal developments, but – perhaps reflecting a mature and well developed technology – quite a number of the rest were concerned with manufacturing methods rather than novel designs. Seal component related patents have the manufacture of seals from wear-resistant materials or coatings, and also anti-rotation device design. Another was concerned with a providing a seal during maintenance on mixers (WO 03/064898, October). In February there was a very complicated seal arrangement for the rotary joints on a diving suit, WO 03/097443. An interesting feature of this seal is that it is designed to fail-safe to isolate the interior of the diving suit if the face seal fails. Although no further movement is possible once it has assumed the fail-safe condition, this idea could have applications for hazardous process conditions. A close competitor to gas mechanical seals, in some applications, are the various forms of turbine clearance seal. Eight patents were covered dealing with these during the year, mainly in the currently popular area of brush seals. One patent describing the background technology was covered in detail in April 2003 (US 6505835), and provides a useful introduction if required. As we have seen, the largest number of gasket patents was concerned with internal combustion engine cylinder heads. The next most prolific area for gaskets was in an area that may be considered a future competitor to the cylinder head gasket: fuel cells. Fuel cells will require a large number of seals, and it is interesting that some of these patents describe manufacturing and assembly in addition to the gasket itself. Those valve seals that were not concerned with reciprocating machinery were primarily valve seats for several different types of process valve. Some were subtle and simple designs to improve valve sealing performance, such as the revised seat seal geometry in WO 03/098081 this month. Others appear to have quite complex designs to increase seating stress, such as WO 03/089820 (February). Outside the automotive industry the window and door seals were primarily concerned with buildings, or in one case ducts within a building. Several were seals for smoke-stop doors. A similarity with the automotive seals is the complexity of the shapes that are patented as the designer endeavours to provide an adequate seal with minimum sealing force on surfaces that are not necessarily well aligned or even. The majority of bearing and other lip seals came within the automotive area. Others were primarily concerned with the manufacture of PTFE seals.
Sealing Technology March 2004
PATENTS The numerous pipefitting designs cover a very wide range, and in most cases these were quite specific to a type of application. Some appear to be quite complex with a considerable number of components; WO 03/100309 provides an example in this issue. Magnetic seals have been around for probably 30 years, and efforts to extend their appeal continue. The patents this year have been divided between those concerned with configurations for particular applications, either feed-through or disc drives, WO 03/087636 (last month) and others with the seal design. This month, WO 03/104689 describes the geometry of the magnetic poles on the stator, but in WO 03/016755 (April) an arrangement is described that is also able to cope with axial shaft movement.
The piston ring patents have primarily been concerned with the design of the joint to provide a benefit in particular circumstances. A further example of a technology searching for a sealing solution to make it more commercially viable is the Stirling cycle machine, and during the year three patents described features of the displacer unit.
Conclusions Providing the patent abstracts is an interesting, if slightly time-consuming, part of the editing this newsletter. If the patents are in a topic area that I know well it is gratifying to see developments continuing.
Since becoming Editor I have adopted the policy of trying to provide a brief overview of the patent subject, and also the reasoning behind the application. As a user this is how I would like to use this section; the idea is that readers will be able to scan the section for subjects of interest to themselves and, if particularly interested for either technical or commercial reasons, then look into the patent itself. And, as an engineer writing for engineers, I have decided that a picture is worth a thousand words and introduced rather more illustrations and less text. I would appreciate your comments on both the style and the content of the Patents section. And if sometimes there does not seem to be much information, it may be because there is only a 50word abstract in English for me to use.
Patents Metal end cap seal with pressure trap Applicant: Cooper Cameron Corporation, USA A metal end cap seal for a similar duty to WO/095872. In this design the inner diameter of the resilient ring has one or more circumferential cavities open to the inner diameter, that are connected to the outer diameter by radial holes. After the seal is energized, a high pressure is applied to the seal so that the pressure will migrate past the nose of the seal, through the radial holes, and into the groove. The groove is shaped so that, once the high pressure is relieved, the pressure within the groove will become trapped. This trapped pressure acts as a source of stored energy, to increase the energization of the seal. The purpose is to enable the seal to function more effectively at low temperatures. Patent number: WO 03/095873
Inventors: K.E. Keene and D.K. Wolff Publication date: November 2003
Sealing Technology March 2004
Applicant: Polymer Sealing Solutions Ltd, UK This patent is particularly concerned with the static sealing of truck wheel bearing hubs. A seal has a reinforcing insert (7) and a resilient projection (5). It is arranged to be a snap-fit within an annular recess formed within a bearing. The bearing has a retention lip (15) adjacent to the recess, against which the resilient lip of the seal abuts and resists removal. Patent number: WO 03/095856
Inventors: D.M. Williamson and G. Sturman Publication date: 20 November 2003
The snap fit seal for truck bearings described in WO 03/095856.
Method of influencing the rigidity of a vehicle door window seal The metal end cap seal with additional pressurization groove, in WO 03/095873.
Metal end cap seal with annular protrusions Applicant: Cooper Cameron Corporation, USA A further design of metal end cap seal designed to improve sealing at an increased range of temperatures. The seal generally has a resilient ring with a metal end cap on each end. The inner diameter of the resilient ring has one or more annular protrusions along the inside diameter of the resilient
Static seal between bearing ring and shaft
ring. The annular protrusions are sized to provide additional interference with the internal tubular member and provide areas of localized compressive stress within the resilient ring, while maintaining a desirable overall stress distribution. Patent number: WO 03/095874 Inventors: K.E. Keene et al. Publication date: 20 November 2003
Applicant: Metzeler Automotive Profile Systems GmbH, Germany In this patent an elastomer seal (20) is fitted to a frame (40) and closed against a window (30). It may have one or several sealing lips (22) that rest against the window. To improve the sealing system and obtain a variable sealing effect, that is adapted to environmental factors, the sealing lips are provided with a piezo-ceramic actuator (50) and can be pressed against the window using a voltage applied to the actuator. Patent number: WO 03/104008 Inventor: C. Huck Publication date: 18 December 2003
Vehicle window door seal from WO 03/104008, with piezoceramic actuators to increase the sealing force.
13