Live loaded valve stem packing with shape memory alloy option
US6354566B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 24, 2000 |
| Grant date | Mar 12, 2002 |
| Priority date | — |
| Expiry date | Jul 24, 2020 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF16J15/186
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
Live loaded valve stem packing wherein grafoil packing is molded into a metal cap that prevents extrusion of the packing, and has live loading built into the metal cap. This metal cap can be conventional flat spring materials (17-7PH S.S. or 302 S.S.) or a Shape Memory Alloy (commonly known as SMA materials, e.g. Ni—Ti (Nickel-Titanium alloy) or Fe—Si—Mn (Iron-Silicon-Manganese alloy). The cap is designed with a singular hump, entirely along its top surface. On this hump there are two slots through the hump, 180 degrees apart, for ease of removing the packing. Upon assembly of the packing box, the hump is elastically flattened out due to axial loading through the fasteners. As the packing consolidates during service (optionally if the cap is SMA, during temperature increases) the hump deflects to maintain a relatively constant or enhanced axial load on the packing to enhance sealing, even during a fire.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.