EP 0241870 B1 19920102 - HYDRAULIC CONTROL DEVICE
Title (en)
HYDRAULIC CONTROL DEVICE
Publication
Application
Priority
DE 3612684 A 19860415
Abstract (en)
[origin: US4744542A] The invention relates to a hydraulic control apparatus comprising a hydraulically adjustable throttle opening between an inlet passage and an outlet passage, a three-way pilot valve connected to an external actuator and having its inlet connected to a control pressure inlet passage, its control outlet being connected to the throttle valve in such a manner that the throttle valve element thereof is adapted to be biased in opposition to the pressure in the outlet passage and to the force of a spring. Known control apparatus require the employ of a displacement sensor for sensing the position or displacement of the throttle valve element and for correspondingly acting on the actuator to thereby vary the actuating force thereof for maintaining the opening degree of the throttle opening. This construction involves considerable complications. It is also disadvantageous that the pilot valve is subjected to the full operating pressure, requiring it to be of a highly accurate and therefor expensive construction. According to the invention the second outlet of the three-way pilot valve is connected to the outlet passage, and the valve element of the pilot valve is subjected to the pressure at the control outlet in opposition to the actuating force and to the pressure at the second outlet, and the inlet pressure supplied to the pilot valve is higher than the outlet pressure at least by the maximum possible pressure difference over the pilot valve.
IPC 1-7
IPC 8 full level
G05D 16/16 (2006.01); F15B 11/04 (2006.01); F15B 13/02 (2006.01)
CPC (source: EP US)
F15B 13/02 (2013.01 - EP US)
Designated contracting state (EPC)
AT BE CH DE ES FR GB GR IT LI LU NL SE
DOCDB simple family (publication)
EP 0241870 A2 19871021; EP 0241870 A3 19891025; EP 0241870 B1 19920102; AT E71191 T1 19920115; DE 3612684 A1 19871022; DE 3612684 C2 19880929; DE 3775594 D1 19920213; ES 2029234 T3 19920801; GR 3003832 T3 19930316; JP 2667827 B2 19971027; JP S62269211 A 19871121; US 4744542 A 19880517
DOCDB simple family (application)
EP 87105284 A 19870409; AT 87105284 T 19870409; DE 3612684 A 19860415; DE 3775594 T 19870409; ES 87105284 T 19870409; GR 920400254 T 19920218; JP 8995487 A 19870414; US 3702887 A 19870410