(19)

(11)

EP 0 567 589 A1

(12)

(43) Date of publication: 03.11.1993 Bulletin 1993/44 (21) Application number: 92905376.0 (22) Date of filing: 08.01.1992

(51) International Patent Classification (IPC):  F04D 29/ 28( . ) (86) International application number: PCT/US1992/000319 (87) International publication number: WO 1992/013197 (06.08.1992 Gazette 1992/21)

(84) Designated Contracting States: DE FR IT (30) Priority: 15.01.1991 US 19910641432 (71) Applicant: NORTHERN RESEARCH & ENGINEERING CORPORATION Woburn, MA 01801-2073 (US)	(72) Inventors: JANSEN, William Weston, MA 02193 (US) PLATT, Melvin Holliston, MA 01746 (US) (74) Representative: Feakins, Graham Allan, et al  RAWORTH, MOSS & COOK RAWORTH HOUSE 36 Sydenham Road Croydon, Surrey CRO 2EF Croydon, Surrey CRO 2EF (GB)