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