(19)
(11) EP 0 684 387 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
30.10.1996 Bulletin 1996/44

(43) Date of publication A2:
29.11.1995 Bulletin 1995/48

(21) Application number: 95202286.1

(22) Date of filing: 23.12.1992
(51) International Patent Classification (IPC)6: F15B 11/05
(84) Designated Contracting States:
DE FR GB

(30) Priority: 25.12.1991 JP 357128/91
16.07.1992 JP 212244/92
26.08.1992 JP 250517/92

(62) Application number of the earlier application in accordance with Art. 76 EPC:
92311770.9 / 0550257

(71) Applicant: KAYABA INDUSTRY CO., LTD.
Minato-Ku, Tokyo 105 (JP)

(72) Inventors:
  • Koiwai, Hideshi
    Toda-shi, Saitama-ken (JP)
  • Naito, Hisato
    Kanagawa-ken (JP)
  • Yonekubo, Yoshitake
    Setagaya-ku, Tokyo (JP)
  • Nishiumi, Kenichi
    Tama-ku, Kawasaki-shi, Kanagawa-ken (JP)
  • Hasegawa, Yoshimi
    Yachiyo-Shi, Chiba-ken (JP)

(74) Representative: Carpmael, John William Maurice 
CARPMAELS & RANSFORD 43 Bloomsbury Square
London, WC1A 2RA
London, WC1A 2RA (GB)

 
Remarks:
This application was filed on 23 - 08 - 1995 as a divisional application to the application mentioned under INID code 60.
 


(54) Load-sensing active hydraulic control device


(57) A load-sensing active hydraulic control device is disclosed in which a plurality of cylinders (19,20) are connected in parallel and fed with hydraulic fluid from a variable discharge pump (1), thereby to control the variable discharge pump depending on horsepower constant control characteristics and which is capable of preventing, when one cylinder (20) is increased in load pressure, actuation of the other cylinder (19) from being stopped due to a decrease in the amount of hydraulic fluid discharged from the pump. A pilot valve (25) is provided which is changed over by a pressure actuation of a passage (18) of the one cylinder (20). The pilot valve is open to communicate a pilot chamber (4b) of a change-over valve (4) with a tank (T) when a pressure in the passage approaches a set pressure of an overload relief valve (22) of the passage. This results in a degree of opening of a variable orifice (6) of the change-over valve being reduced to decrease the amount of hydraulic fluid fed to the cylinder (20), thereby to ensure feeding of hydraulic fluid to the cylinder (19) correspondingly.






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