Patents

P a t e n t s This is a l is t of r e c e n t l y p u b l i s h e d p a t e n t s cover ing d e s i g n s a n d inven t ions of r e l evance to Sealing Technology r e a d e r s . C o u n t r i e s can be ident i f ied by the code in f ront of the n u m b e r :

AT A u s t r i a US Uni ted S t a t e s BE Belg ium AU A u s t r a l i a CA C a n a d a BR Brazi l CH S w i t z e r l a n d D G e r m a n y EP E u r o p e a n P a t e n t ES S p a i n FR F r a n c e FI F i n l a n d HU H u n g a r y GB Br i t a in IR Ei re IL Is rae l J P J a p a n IT I ta ly LI L i ech t ens t e in KP Nor th Korea NL N e t h e r l a n d s LU Luxembourf{ RO R o m a n i a NO Norway SU F o r m e r Sovie t

Union SE S w e d e n WO World P a t e n t

Full copies of the or ig ina l p a t e n t d o c u m e n t s can be o b t a i n e d from the following:

The British Library Patent Express, 25 S o u t h a m p t o n Buildings London WC2A lAW, UK Fax: +44 171 4 1 2 7 9 3 0

The Br i t i sh L ib ra ry will a l so s u p p l y a l is t of l i b r a r i e s i n c l u d e d in t he Pa t en t I n f o r m a t i o n Network.

US Patent Office Sc ient i f ic Library 15th and East Streets , NW Washington, DC 2 0 2 3 1 , USA

The J a p a n e s e Patent Office 43 Kaksumigasek i 3 - c h o m e Chiyoda-ku, T o k y o I00 , Japan

Mechanical seal with compliant face Patent number: U S 5 4 9 9 8 2 4 Publicat ion date: 19 March 1996 Inventor: Richard Salant Assignee: Georgia Tech Research Corporation

This inven t ion a i m s to improve the s t i f fness c h a r a c t e r i s t i c s of h y d r o s t a t i c sea l s , a n d h e n c e i n c r e a s e the eff iciency a n d re l iab i l i ty of the seal , by u s i n g a c o m p l i a n t sea l face.

The p re fe r red ve r s ion (Figure 1) h a s a sea l ing r ing m o u n t e d on the sha f t s u c h t h a t it can s l ide b u t no t

In o p e r a t i o n the sea l expe r i ences a p r e s s u r e d i s t r i b u t i o n t ha t is h i g h e s t a t the o u t s i d e d iamete r . Conse que n t l y , the c o m p l i a n t face u n d e r g o e s pos i t ive coning, w h i c h r e s u l t s in t he des i r ed pos i t ive s t i f fness . Even if the b a s e expe r i ences nega t ive coning, w h i c h wou ld n o r m a l l y c a u s e sea l ins tab i l i ty , the e las t i c I o u n d a t i o n can be c h o s e n s u c h t h a t t he lbil d e f o r m a t i o n p r o d u c e s e n o u g h posi t ive con ing to c o m p e n s a t e . Sea l s t ab i l i ty is e n s u r e d .

The p e r f o r m ; r a c e c h a r a c t e r i s t i c s of the c o m p l i a n t sea l c a n be improved by i n c r e a s i n g the s t i f fness of the e las t ic f o u n d a t i o n t o w a r d s the i n n e r d i ame te r . Th is can be ach ieved by r ad i a l l y i n c r e a s i n g the foam dens i ty , or by a se r i e s of sma l l s p r i n g s of va ry ing s t i f fness .

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Figure I. The elast ic foundat ion is des igned to ensure pos i t ive coning .

ro ta te . The r ing is m a d e f rom a h a r d m a t e r i a l s u c h as t u n g s t e n ca rb ide , a n d effectively f loats on the shaf t . Th is is a c c o m p l i s h e d by fixing a s p r i n g to it, wh ich is a t t a c h e d to a n o t h e r sea l ing r ing m o u n t e d in t he h o u s i n g on a b a s e of a m a t e r i a l l ike s t a i n l e s s s teel . This s e c o n d r ing h a s a flat face oppos i t e the f loat ing face of the f irst r ing.

Aff~:ed to th i s face is a n e las t ic f o u n d a t i o n s u c h a s a n e l a s tomer i c foam. On the s u r f a c e is a foil s k i n of a m a t e r i a l l ike b o r o n n i t r ide , w h i c h fo rms the s e c o n d flat face. O t h e r ma te r i a l s , or sp r ings , can be u s e d to c r ea t e th i s e las t ic founda t ion .

Secondary gas/l iquid mechanical seal assembly Patent number: U S 5 4 8 7 5 5 0 Publicat ion date: 3 0 January 1 9 9 6 Inventors: R Salant, I Green, L Hufford, O Giles Assignee: BW/IP Internat ional

Minu te l e a k s p r o d u c e d by a p r i m a r y l i qu id - type sea l a s s e m b l y a r e often in g a s e o u s p h a s e . The

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