| 摘要 |
The present invention relates to an electro-pneumatic positioner for use wit h a pneumatically controlled two-chamber actuator comprising a first valve uni t (10) comprising a first air supply valve (14) and a first air outlet valve (37) connected to a conduit (30, 38, 50), which in turn is connectable to a chamber of the actuator, a second valve unit (12) comprising a second air supply valve (14') and a second air outlet valve (37') connected to a condui t (30', 38', 50'), which in turn is connected to a second chamber of the actuator; a first control device (60, 74) acting on the first air supply valve, which first control device comprises a first control valve (60); a second control device (60', 76) acting on the said second air supply valve, which second control device comprises a second control valve (60'). The invention is characterised in that said first control device further compris es a first air supply means (74) able of supplying pressurised air to said firs t air supply valve (14) and that said first control valve (60) acts on and controls said first air supply means (74); that said second control device further comprises a second air supply means (76) able of supplying pressuris ed air to said second air supply valve (14') and that said second control valve (60') acts on and controls said second air supply means (76); that said firs t air supply means (74) is able of supplying air to said second air outlet val ve (37'), and that said second air supply means (76) is able of supplying air t o said first air outlet valve (37).
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