(19)
(11) EP 0 390 298 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
31.10.1990 Bulletin 1990/44

(43) Date of publication A2:
03.10.1990 Bulletin 1990/40

(21) Application number: 90201581.7

(22) Date of filing: 16.03.1989
(51) International Patent Classification (IPC)5: F04B 21/04, F04B 43/06, F04B 21/02, F04B 43/10
(84) Designated Contracting States:
CH DE FR GB IT LI SE

(30) Priority: 23.03.1988 JP 68882/88
30.03.1988 JP 77076/88
26.04.1988 JP 103232/89

(62) Application number of the earlier application in accordance with Art. 76 EPC:
89302606.2 / 0343773

(71) Applicants:
  • KABUSHIKI KAISHA LITTLE ROCK
    Chiba-shi Chiba-pref. (JP)
  • Koiwa, Yoshinobu
    Chiba-shi Chiba-pref. (JP)
  • KELBIN CO., LTD.
    Tokyo (JP)
  • Fujimori, Shuichi
    Fujisawa-shi Kanagawa-pref. (JP)

(72) Inventor:
  • Koiwa, Yoshinobu
    Chiba-shi, Chiba-pref. (JP)

(74) Representative: Newstead, Michael John et al
Page Hargrave Temple Gate House Temple Gate
Bristol BS1 6PL
Bristol BS1 6PL (GB)


(56) References cited: : 
   
     
    Remarks:
    This application was filed on 18 - 06 - 1990 as a divisional application to the application mentioned under INID code 60.
     


    (54) Fluid pump apparatus


    (57) In fluid pump apparatus in which the reciprocating action of a piston (3) provided in a cylinder (21) draws fluid into a valve chamber (1) and pumps fluid (14) from the valve chamber, a pressure-action chamber (5a) is provided between the cylinder and the valve chamber, the pressure-action chamber being filled with a liquid (28) that has a different specific gravity than that of the said fluid. A passage (17) that connects the pressure-action chamber and the valve chamber is provided at a position at which the height relative to the pressure-action chamber and the valve chamber is such that the liquid does not flow owing to the difference in specific gravity between the liquid and the fluid.







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