Window assemblies (see figure) have been developed to satisfy special requirements pertaining to ease of replacement, alignment, sealing, and resistance to vibration in a spaceborne laboratory apparatus for experiments on combustion in microgravity. These window assemblies are also well suited to a variety of terrestrial applications; for example, they could used as observation ports or as mechanical or electrical feedthrough devices on industrial process chambers, vacuum chambers, or oceanographic equipment.
The windows can be installed and removed manually, without tools. Each window mates with a seat that is a permanent part of the chamber in which the window is to be installed. All one need do to install a window is to align it approximately with the seat, then rotate the window one turn. The rotation brings the window into alignment, brings sealing surfaces together to make a vacuum- or pressure-tight seal, and provides a vibration-proof connection. The window gives a firm feel when it becomes seated.
This mode of operation of the window is established by a unique combination of threads, sealing features, and a ratchet. A multiple-lead acme thread ensures an easy start. Because the seal acts on a bore in the chamber wall, instead of on a face parallel to the plane of the window, there is no need for the large clamping force that would be needed for a face seal. The ratchet includes a spring-loaded dimple plate acting on tapered lands. The lands are cut steeper in the window-removal than in the window-installation direction, so that more torque is needed to remove than to install the window; this feature helps to prevent loosening in the presence of vibrations.
This work was done by Malcolm Robbie of Analex Corp. and Raymond Homyk of ADF for Lewis Research Center.
Inquiries concerning rights for the commercial use of this invention should be addressed to
NASA Lewis Research Center
Commercial Technology Office
Attn: Tech Brief Patent Status
Mail Stop 7-3
21000 Brookpark Road
Refer to LEW-16529.