(19)
(11) EP 2 264 319 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
21.05.2014 Bulletin 2014/21

(43) Date of publication A2:
22.12.2010 Bulletin 2010/51

(21) Application number: 10164131.4

(22) Date of filing: 27.05.2010
(51) International Patent Classification (IPC): 
F04C 18/16(2006.01)
F04C 29/06(2006.01)
F04C 18/08(2006.01)
 F04C 29/00(2006.01)
F04C 29/12(2006.01)
(84) Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO SE SI SK SM TR
Designated Extension States:
BA ME RS

(30) Priority: 28.05.2009 JP 2009129389

(71) Applicant: Hitachi, Ltd.
Chiyoda-ku Tokyo (JP)

(72) Inventors:
  • Saito, Takashi
    Tokyo 170-8466 (JP)
  • Tsuru, Seiji
    Tokyo 170-8466 (JP)
  • Uchida, Toshikazu
    Tokyo 100-8220 (JP)

(74) Representative: Beetz & Partner 
Patentanwälte Steinsdorfstraße 10
80538 München
80538 München (DE)

   


(54) Oil free screw compressor


(57) An oil free screw compressor comprises: a pair of male and female screw rotors (1,2) in which two or more twisted teeth are formed; a casing (3) which receives both the rotors (1,2) and in which a suction port and a discharge port are formed; and bearings (11-14) which rotatably support shaft end parts of both the rotors (1,2) and are held in the casing (3). There is provided a slot (6), next to the discharge port of the casing (3), which comes into communication with the discharge port with timing where a volume of a compression chamber formed by both the rotors (1,2) and the casing (3) becomes substantially zero as both the rotors (1,2) rotate, to prevent problems such as excessive compression.







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Search report