Patent GB-754259-A (GB)
Title: Means for the automatic regulation of the air cushion in pressure tanks of liquid supply systems operating at high working pressure
IPC: G05D9/04
Filed: 1954-04-20
Abstract: 754,259. Regulating liquid levels. KRACHT PUMPEN-UND MOTORENFABRIK GES. April 20, 1954 [April 21, 1953], No. 11284/54. Class 123(1) In a high pressure liquid supply system wherein the liquid, for example, oil, is contained in a pressurized storage tank 1 in which a level 4 is maintained by a pump controlled by means responsive to the variations in pressure of the air cushion trapped above the liquid surface, an apparatus is provided which serves automatically to replenish the air cushion which in service tends to decrease in volume over a period of time. As shown in the Figures, the apparatus consists of a float chamber 3 enclosed by a hood 5 the top of which is connected by a pipe 2 to tank 1 at the level 4, the hood being secured to a valve body 6. A float 7 of greater specific gravity than the liquid is housed in chamber 3 and carries a control piston 8 slidably mounted in a bore 9 in the valve body, a spring 10 exerting an upward force on the piston and float such that the latter rises when a certain quantity of liquid enters chamber 3 due to a decrease in volume of the air cushion in tank 1 and consequent overflow of liquid therefrom into pipe 2. Also proivded on the valve body 6 is a piston pump comprising a vertical cylinder 18 having a cover 22, a piston 19 and a piston rod 20 which passes through a packed gland in the cover and carries an arm 34 to one end of which is attached a tension spring 35, the other end carrying a control rod 38 on which are mounted striking members 44, 45 adapted to actuate a second control piston 48 vertically slidable in a bore in valve body 6. The piston 48 is waisted to provide an annular space 53 which which a channel 17 from bore 9 and a connection 54 from the space 55 below piston 19 communicate. Upper and lower hoods 30, 59 secured to the valve body 6 respectively enclose the regulator parts above and below the valve body, the upper hood having an air inlet 31 from atmosphere whilst the lower has an oil drain pipe 60 leading to a collecting tank 61. In operation, if the oil for example, level in tank 1 exceeds level 4, oil flows into chamber 3, float 7 lifts and oil at the working pressure flows through a duct 13 in valve 8 into duct 17 exposed by the lifting of the valve and thence through duct 54 to space 55. Piston 19 rises compressing air above it to the working pressure and, since its lower side has a greater area exposed to this pressure, continues to rise, a spring-loaded check valve, not shown, in cover 22 opening to allow the air to flow through duct 33 into chamber 3 and thence into tank 1 to replenish the air cushion. When piston 19 has displaced all the air from the space 21 thereabove, some of a quantity of oil 24 resting on and sealing the piston passes into duct 33 to displace the air therein. At this time member 44 moves piston 48 to its upper position thus closing duct 17 and connecting duct 54 with a duct 56 which extends upwardly through body 6 and terminates in a horizontal nozzle 57. The spring 35 brings the piston back to its lower position, sucking a fresh charge of air into space 21 through a valve 25, the valve in line 33 closing under the pressure in chamber 3. The oil in space 55 flows through ducts 54, 56 to issue as a jet from nozzle 57 into hood 30 whence it drains into the lower hood and collecting tank 61. At the end of the stroke of piston 19 the velocity of the jet from nozzle 57 decreases and a quantity of the oil falls into a funnel 28 whence it is sucked through valve 25 to replenish the quantity of oil 24 on the piston. At this time member 45 on rod 38 moves piston 48 back to its original position and another cycle of the controller may commence,' the cycles continuing until the oil level in tank 1 has been restored to level 4 corresponding to an air cushion of the correct volume.