Patent GB-1398039-A (GB)
Title: Pumping units
IPC: F04B49/00
Filed: 1973-05-25
Abstract: 1398039 Reciprocating pumps VSESOJUZNY NAUCHNO-ISSLEDOVATELSKY I PROEKTNO-KONSTRUKTORSKY INSTITUT NEFTYANOGO MASHINOSTROENIA 25 May 1973 25244/73 Heading F1A A pump, e.g. for drilling mud, comprises at least two units 1, 2 each comprising pumping cylinders 4 with reciprocable pistons 3, e.g. driven by a crank gear. In the double-acting arrangement of Fig. 1, each working chamber 6, 7 is connected to a respective hydropneumatic accumulator with a piston 11 defining a gas space 10. The gas spaces 10 of each unit are connected to a respective compressor 14, a connection to atmosphere 15, and through pipes 30, 32 to working chambers 29, 31 on either side of a piston 25 controlling a valve 24', 28 in a connection 22 between the inlet manifold 16 and outlet manifold 17. In operation, with valve 33 between pipes 30 and 32 open, units 1 and 2 operate in parallel, and their capacity is adjusted by adjusting the gas pressure in accumulator spaces 10 using compressors 14 and valves 15, valve 24', 28 being closed. Pulsation dampers 18 are provided in the outlet manifold 17. For tandem operation of units 1 and 2, valve 33 is closed, and the accumulator pressure of unit 2 is set at the expected discharge line 21 pressure and the accumulator pressure of unit 1 is set at half the discharge line pressure. Valve 24', 28 then opens, and when pumping is started check valves 19 and 20 close, so that unit 1 delivers to unit 2. In the single-acting arrangement of Fig. 3, the chambers 34 beneath the pumping pistons 38 of each unit are filled with a lubricating liquid free of mechanical impurities and are connected to a common accumulator 43, a make-up pump 45, a valve 46 connected to a reservoir 47, and through pipes 30, 32 to control chambers 29, 31 of valve 24', 28. Pistons 38 are slidable on actuating rods 39 as far as stops 38 so that their delivery stroke length depends on the delivery head and the pressure in chambers 34, which is adjusted by pumps 45 and valves 46. For parallel operation of units 1 and 2, valve 48 is open, and for tandem operation valve 48 is closed, valves 24', 28, 19 and 20 operating as in the Fig. 1 arrangement. In Fig. 5 (not shown), units 1 and 2 have single-acting pumps, as in Fig. 3, but their accumulators (43) are connected on their hydraulic side to a control valve (59). For parallel operation, valve (59) is set in its middle position by a handle (68) so that the accumulators (43) of the units 1, 2 are connected. For tandem operation, pressure-relief valves (72) of the accumulator systems of units 1 and 2 are set at half the required discharge line pressure, and the required discharge line pressure, respectively, valve (59) is unlocked and automatically operates a switch (66, 67) controlling a make-up pump (45) to set the accumulator system pressures in the ratio 2:1. During operation, the valve (59) automatically moves to maintain the required pressure ratio. The pump piston rods of the unit 2 of the Figs.3 and 5 embodiments have seals, Fig. 4 (not shown), each including a chamber (49) connected to the hydraulic side of the unit 1 accumulator system.