An electro-pneumatic signal converter for converting an electrical current signal into a pneumatic pressure, comprising a force balancing system where a magnetic force is balanced against a pneumatic force, consists of a coil (11) through which the electrical signal current flows, a magnetic circuit comprising a core (12) of ferromagnetic material disposed in the coil (11) with a nozzle chamber (14) with a mouth in the form of a nozzle (13) in one end of the core, a flapper (17) of ferromagnetic material over the nozzle and a link (16) of ferromagnetic material which closes the magnetic circuit between the flapper and the opposite end of the core, a feed line (19, 19A, 19B) for a constant flow of feed air into the nozzle chamber (14) and out again through the nozzle (13) into the gap (25) between the nozzle and the flapper, and a pressure-sensing line (24) from the nozzle chamber to a pressure-dependent member (7) to transmit a pneumatic pressure signal from the nozzle chamber to the pressure-dependent member.
展开▼
