(19)
(11) EP 1 130 263 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
24.07.2002 Bulletin 2002/30

(43) Date of publication A2:
05.09.2001 Bulletin 2001/36

(21) Application number: 01301502.9

(22) Date of filing: 20.02.2001
(51) International Patent Classification (IPC)7: F04C 18/16
(84) Designated Contracting States:
AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE TR
Designated Extension States:
AL LT LV MK RO SI

(30) Priority: 23.02.2000 GB 0004263

(71) Applicant: The BOC Group plc
Windlesham Surrey GU20 6HJ (GB)

(72) Inventor:
  • North, Michael Henry
    Surrey, RH2 7DA (GB)

(74) Representative: Bousfield, Roger James et al
The BOC Group plc Chertsey Road
Windlesham Surrey GU20 6HJ
Windlesham Surrey GU20 6HJ (GB)

   


(54) Helical gear vacuum pump


(57) A vacuum pump includes a pump body 20 in which is mounted two externally threaded rotors 7,8. The thread profile of each rotor is tapered in a substantially radial direction to facilitate the machining and fitting of the rotors 7,8 with the required close tolerances.






Search report