(19)
(11) EP 0 227 296 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
22.03.1989 Bulletin 1989/12

(43) Date of publication A2:
01.07.1987 Bulletin 1987/27

(21) Application number: 86308993.4

(22) Date of filing: 18.11.1986
(51) International Patent Classification (IPC)4: B66B 1/04, F15B 21/08
(84) Designated Contracting States:
CH DE FR GB IT LI NL SE

(30) Priority: 18.11.1985 US 799665
18.11.1985 US 799765
17.04.1986 US 853284
17.04.1986 US 853286

(71) Applicant: OTIS ELEVATOR COMPANY
Farmington, CT 06032 (US)

(72) Inventors:
  • Fossati, Giorgio
    I-20052 Monza Milano (IT)
  • Manco, Giuseppe
    I-201 Agrate Brianza Milano (IT)
  • Terry, Harold
    I-20075 Vedano Al Lambro Milano (IT)

(74) Representative: Tomlinson, Kerry John et al
Frank B. Dehn & Co., European Patent Attorneys, 179 Queen Victoria Street
London EC4V 4EL
London EC4V 4EL (GB)


(56) References cited: : 
   
       


    (54) Pressure-referenced programmed flow control in a hydraulic valve


    (57) The point at which pump out pressure exceeds load is sensed to provide a point for scheduling flow to an actuator in a hydraulic system, such as an elevator. Flow is controlled by a stepper motor (28) that moves a flow control valve (27). When the pump (21) is turned on, the valve (27) is positioned to bypass flow; the bypass flow is then programmably decreased to increase the flow to the actuator. Reverse flow is regulated by the valve (27) to control actuator retraction. Reverse flow is initiated by opening a check valve (40) with an actuator (50) that opens it first to reduce pressure across the valve, then fully. The flow control valve (27) also operates to relieve excess pressure in the system.






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