PATENTS

14Sealing Technology January 2013

portion is displaced radially outwards in order to permit fluid flow between the shaft and the seal body. A rigid support member is disposed within the body outer portion so as to be locat-ed at least partially within the housing recess and, is configured to reduce the deflection of the body inner portion to prevent disengage-ment of the body from the recess.Patent number: WO/2012/103467Inventor: S.M. BarthPublication date: 2 August 2012

Gasket

Applicant: Ningbo Tiansheng Sealing Packing Co Ltd, ChinaA gasket for use in a pipeline flange connection and a sealing connection between a valve and a pressure container are described. The gas-ket, whose stress relaxation ratio falls within a controllable range, has built-in sensors that are connected to an external computer. The gasket includes an inner ring, an outer ring and a mid-dle ring. The inner and outer rings are made from metal, while the middle one is made from flexible graphite (content more than 99%), or polytetrafluoroethylene. The stress relaxation ratio – an important parameter of this gasket – is analysed by detecting its temperature and pressure in real time. In this way this ratio is monitored continuously. The analysis deter-mines whether or not the parameters of the gasket satisfy the stress relaxation ratio specified in the design requirements. Therefore, the seal-ing function state of the gasket is obtained in real time.Patent number: WO/2012/103673Inventors: H. Li and W. SongPublication date: 9 August 2012

Seal for a hydraulic piston–cylinder arrangement

Applicant: Schaeffler Technologies Ag & Co Kg, GermanyA seal has been developed for a hydraulic pis-ton–cylinder arrangement within a hydraulic path that actuates a clutch or brake. The seal is designed to accomplish adequate sealing under low pressure and high pressure. The generation of noise – in particular as a result of the so-called stick-slip effect – is reduced.Patent number: WO/2012/107015Inventors: A. Schoch and P. WagnerPublication date: 16 August 2012

Labyrinth seal

Applicant: Schaeffler Technologies Ag & Co Kg, GermanyIn summary, this invention relates to an assem-

bly for sealing a radial rolling contact bearing. The patent describes first and second sealing rings, both of which can be rotated relative to each other about a common axis of rotation and, together, form a labyrinth seal. The seal-ing gap of this seal, which extends substantially radially with respect to the axis of rotation, is covered radially by an axial projection of the second sealing ring. The sealing gap, at the axial projection, opens into a first catch channel of the first sealing ring. The aim is to specify a seal arrangement that has a low number of components, achieves high sealing action with little friction, but permits simple assembly. According to this patent, the hub of the radial rolling contact bearing forms the second sealing ring. Therefore, this second ring is integrated into the hub flange. This means that the flange performs the function of the second sealing ring and, to some extent, helps to form the labyrinth seal.Patent number: WO/2012/107118Inventors: A. Häpp and W.WalterPublication date: 16 August 2012

Drill bit seal

Applicant: National Oilwell Varco Lp, USADetails are disclosed of a sealed and lubricated rolling cutter earth-boring drill bit, including a drill-bit seal, such as a packing resistant lip seal and, in particular, a seal that upon instal-lation provides one or more closed air gaps within the cutter. The seal is generally oval in shape, with its width greater than its thickness. It has cavities formed in its sides. When this seal is installed in a groove in the rolling cut-ter, the edges of each cavity (on the sides and/or ends of the seal) come in contact with the seal groove and form air-gap volumes between the seal and walls of the groove. The asym-metric shape of the seal (50) may result in a non-uniform, biased load being applied to it. A central area of the seal is arranged to provide more load on the inner lip, or grease lobe, (140) than the outer lip, or mud lobe, (150). This biased load may enhance the sealing abil-ity of the inner lip while decreasing the wear on the outer exclusion lip by reducing the contact force. The shape of the mud cavity (200) above the outer lip (150) will be ‘‘energised’’ by the packing of the cuttings, to better prevent intru-sion of cuttings under the outer lip. In a similar manner, the same effect will act on the outside diameter of the mud-side ‘‘ear’’ (160). The seal body may be provided with a garter spring and/or a textured pattern.Patent number: WO/2012/112333Inventor: B.H. BurrPublication date: 23 August 2012

Sealing methods for a surgical instrument

Applicant: Intuitive Surgical Operations Inc, USAAn assembly and method are disclosed for sealing a surgical instrument that has an internal drive shaft which is subject to lateral displacement. The sealing assembly includes a rigid portion, shaped in such a way that it interfaces with the shaft. A laterally oriented slot is open at a radial perimeter location and configured to receive an O-ring. Apertures are disposed on opposing sides of the slot and are open to the slot. These are configured to receive the drive shaft, and are larger than the shaft to accommodate lateral displace-ment. The slot includes opposing internal sides spaced to interface with opposed axial surfaces of the O-ring seal. The seal inhibits axial transmission of an insufflated gas and/or bodily fluids, while accommodating lateral displacement of the drive shaft.Patent number: WO/2012/112705Inventors: G. Duque, T. Murphy, W. Burbank and G. DachsPublication date: 23 August 2012

Assembly for sealing a sliding interface

Applicant: Cool Energy Inc, USAThis patent describes an assembly for sealing the sliding interface between two objects that are capable of moving with respect to one another, but where the sliding interface must provide a substantial seal against pressure loss. For example, this could be where an assembly seals the sliding interface between a piston and a cylinder, or between a rod and a bushing. Although some features of this invention would be beneficial in applications that use a liquid lubricant, it is particularly

Patent WO/2012/112333 provides details of a seal for a lubricated rolling cutter earth-boring drill bit.

PATENTS

January 2013 Sealing Technology15

beneficial in designs that do not – where the materials of the piston, cylinder and sealing system are chosen additionally for their abil-ity to provide self-lubrication as they slide over each other, while providing low friction and a low wear-rate.Patent number: WO/2012/112297Inventors: L.S. Smith and B.P. NuelPublication date: 23 August 2012

Coiled felt seal for hydraulic cylinder piston

Applicant: Neo Mechanics Ltd, ChinaIn this invention, pistons and piston rods, which are part of hydraulic cylinders, are fit-ted with a coiled felt seal (CFS) in place of a rubber O-ring in order to seal the cylinders. The use of the CSF means that the result-ing piston–cylinder mechanical device has a relatively simple structure, and fewer compo-nents, without the need to employ multiple rubber O-rings. In addition, durability and performance are improved, the device is able to tolerate extreme temperatures, and it pos-sesses enhanced internal pressure capacity. Power loss is also reduced through a decrease in piston–cylinder friction, as is leakage, says the inventor.Patent number: WO/2012/113350Inventor: K.T. ChangPublication date: 30 August 2012

Hydraulic system sealing arrangement

Applicant: Eaton Ltd, UKThe subject of this patent is an arrangement for sealing an interface between two compo-nents in a hydraulic system – for example, forming a face seal in a two-way cartridge valve. Embodiments of this invention aim to provide an arrangement that is durable and robust. It is particularly, but not exclusively, suitable for forming a seal between a cover and an insert of a two-way cartridge valve and avoids the use of a shim in instances when the height of the insert is less than the depth of the bore hole. Other embodiments also aim to provide an improved back-up ring.

Patent number: WO/2012/120383 Inventors: D. Green, J.N. Tamboli and P.S. JadhavPublication date: 13 September 2012

Optical-fibre seal

Applicant: Baker Hughes Inc, USAThe optical-fibre seal described by this patent includes an annular layer that is bonded to an outer glass layer of a length of the fibre. A glass sealing layer is bonded to the outer surface of the annular layer. This design has been devel-oped to withstand conditions in a down-hole environment, with the glass layer hermetically sealing the length of the optical fibre.Patent number: WO/2012/121824Inventors: M.S. Laing, D.S. Homa and R.M. HarmanPublication date: 13 September 2012

Seal assemblies for reciprocating and rotary applications

Applicant: Waters Technologies Corp, USALiquid chromatography is an example of an application in which fluids are pumped at an elevated pressure. Conventionally, high-perfor-mance liquid chromatography (HPLC) employs a pressure range of about 1000 psi and 6000 psi. Pressure for performing ultra-performance liquid chromatography (UPLC) may reach 15 000–20 000 psi. Preventing leakage within pumps operating at any of these fluidic pressures is important to ensure the accuracy of the chro-matographic results. The various embodiments of seal assemblies described in this patent derive from the discovery that leakage of a pressurised fluid – when such leakage occurs – generally appears to be the result of insufficient contact pressure between the outside diameter (OD) of the seal assembly and gland surfaces (typically in the pump head) with which the OD seals. Although increasing the spring rate in the seal assembly could improve the sealing force of the OD, doing this could also negatively affect the effectiveness of the seal provided by the inside diameter (ID) of the seal assembly, for example, by increasing friction, torque and seal wear and, thereby, reducing seal service life. The seal assem-

blies discussed generally improve the OD seal without negatively affecting the ID seal. Tests show that these seal assemblies prevent leakage at approximately 18 000 psi. A simulation has shown that these assemblies are able to prevent leakage at least as high as 20 000 psi, say the inventors. One embodiment employs a pressure-relief feature on the outside diameter of the seal assembly. Compared with a seal assembly without this feature, the contact pressure is lower between the OD and the gland surface (at the locus of the relief feature), with a commensurate increase in contact pressure between the OD and the gland surface elsewhere. Another embodi-ment of the seal assembly forgoes reliance on the OD to provide the seal against the gland surface.Patent number: WO/2012/122445Inventors: J.A. Shreve and N. AlmeidaPublication date: 13 September 2012

Editor’s comment: Also see the feature article entitled ‘Breaking the barrier: why seals alone will not take UHPLC to 20 kpsi and above’, which appears in Sealing Technology April 2012, page 8.

Gasket and seal bead structure

Applicant: NOK Corp, JapanA seal bead structure for a gasket forms the subject of this patent. It is capable of reducing the reactive force generated in a common bead portion provided between multiple through-holes and, thereby, exhibits stabilised sealing action by aligning the compression character-istics over the entire bead. In order to achieve this, two through-holes are provided in a row in the flat portion of a metal gasket – with one seal bead provided on the edge of one through-hole, another provided on the edge of the other through-hole, and a common bead portion, common to both seal beads, provided in the middle portion (between the two through-holes). The common bead portion has a two-level, half-bead shape in which the beads are formed on two levels in the same direction.Patent number: WO/2012/120924Inventors: T. Anzai, M. Ito, S. Nakaoka and I. TanjiPublication date: 13 September 2012