Bellows pump and pumping plant for oil-filled electric cables

A pump for sucking oil under vacuum in a source thereof and supplying such oil to an electric cable under a pressure above atmospheric pressure, said pump comprising:

• an envelope;
• a tubular bellows within said envelope and sealed at an end thereof to said envelope, said bellows being disposed within said envelope so that the outer surface thereof forms an oil receiving chamber with the inner wall of said envelope;
• spring means acting between said bellows and said envelope and urging said bellows to contract;
• a reciprocable piston in said envelope and outside said chamber, said piston being in and coaxial with said bellows and being spaced from said bellows to provide a fluid receiving space between said bellows and said piston;
• a fluid in said fluid receiving space connecting said piston with said bellows for causing reciprocation of a portion of said bellows with reciprocation of said piston;
• a hollow cylinder around said piston in sliding engagement therewith and intermediate said piston and said bellows, said cylinder being sealed to said envelope;
• an intake valve communicating with the interior of said chamber and with the exterior of said chamber for admitting oil into said chamber from said source of oil, said valve having an operating element for opening and closing said valve, said element having an open position and a closed position and in the absence of oil in said chamber being held in its closed position solely by reason of its weight but being movable to its open position with a reduction in pressure in said chamber and the static pressure of the oil from said source;
• and
• a delivery valve communicating with the interior of said chamber and with the exterior of said chamber for delivering oil from said chamber to said cable, said delivery valve having an operating element for opening and closing the latter valve, said last-mentioned element having an open position and a closed position and said delivery valve having resilient means urging said last-mentioned element into said closed position but said last-mentioned element being movable to its open position by oil in said chamber under a pressure sufficient to overcome the force of said resilient means.

A pump for sucking oil under vacuum in a source thereof and supplying such oil to an electric cable under a pressure above atmospheric pressure, said pump comprising:

• an envelope;
• a tubular bellows within said envelope and sealed at an end thereof to said envelope, said bellows being disposed within said envelope so that the outer surface thereof forms an oil receiving chamber with the inner wall of said envelope;
• a reciprocable piston in said envelope and outside said chamber, said piston being in and spaced from said bellows to provide a fluid receiving space between said bellows and said piston;
• a fluid in said fluid receiving space connecting said piston with said bellows for causing reciprocation of a portion of said bellows with reciprocation of said piston;
• fluid supply means at atmospheric pressure connected to said fluid receiving space for supplying said fluid thereto;
• an intake valve communicating with the interior of said chamber and with the exterior of said chamber for admitting oil into said chamber from said source of oil, said valve having an operating element for opening and closing said valve, said element having an open position and a closed position and in the absence of oil in said chamber being held in its closed position solely by reason of its weight but being movable to its open position with a reduction in pressure in said chamber and the static pressure of the oil from said source, said operating element of said intake valve being made of material having a specific gravity less than 2.5 grams per cubic centimeter, said intake valve having a frusto-conical valve seat and the operating element of said intake valve having a frusto-conical terminal portion and an annular elastomeric gasket on said portion engageable with said seat;
• and
• a delivery valve communicating with the interior of said chamber and with the exterior of said chamber for delivering oil from said chamber to said cable, said delivery valve having an operating element for opening and closing the latter valve, said last-mentioned element having an open position and a closed position and said delivery valve having resilient means urging said last-mentioned element into said closed position but said last-mentioned element being movable to its open position by oil in said chamber under a pressure sufficient to overcome the force of said resilient means, said delivery valve having a frusto-conical valve seat and the operating element of said delivery valve having a frusto-conical terminal portion and an annular elastomeric gasket on said portion engageable with said last-mentioned seat.