GB977344A - Improvements in or relating to delivery control valves - Google Patents

Abstract

977,344. Valves. H. TEVES, E. A. TEVES, and M. TAUSEND, [trading as ALFRED TEVES MASCHINEN-UND ARMATURENFABRIK KOMM.-GES.]. Jan. 25, 1962 [May 5, 1961], No. 2830/62. Heading F2V. [Also in Division G3] A delivery control valve, particularly for a rotary vane pump 4, in which a control piston 12 moved against the force of a spring by the pressure difference across a baffle 13 in the delivery pipe to permit fluid delivered by the pump in excess of the quantity determined by the baffle to flow to a tank 3, has a pressurelimiting valve 14 disposed in the piston, operated by the pressure downstream of the baffle and closed by a spring which also operates on the piston 12. The valve is connected to a stop valve 8, amplifier 5 and accumulator 9. When the pump 4 is running fast, the excess delivery forces the piston 12 to the left against springs 17 and 18 so that a groove 22 connects grooves 19 and 20 to provide a direct passage to the tank 3. After the spring 18 has been compressed sufficiently for the end face of the piston 36 to engage a collar 24, delivery is controlled solely by the spring 17 until the pressure in a chamber 34 acting through a passage 33 and a restriction 37 on the annular right-hand face of the sleeve 14 lifts the latter to allow fluid to drain from a chamber 35 through an annular space 31 to the tank 3. As the chamber 35 is drained more quickly than it can be filled the pressure within it falls and causes the piston 12 to move further to the left. When the pump is running slowly, the accumulator may be at a higher pressure than the pump delivery so that there is no flow through the baffle 13, the piston 12 is moved into engagement with the baffle by the springs 17 and 18 which are fully extended, and the valve 14 is opened by the pump delivery pressure against the tank pressure acting on the annular face 30, the closing force on the valve 14 being proportional to the delivery through the baffle 13.