Patent GB-1004845-A (GB)
Title: Improvements in reciprocating pumping apparatus
IPC: F04B15/02
Filed: 1962-07-20
Abstract: 1,004,845. Reciprocating pumps and motors. E. L. SHERROD. July 20, 1962, No. 28051/62. Heading F1A. [Also in Division F2] Pumping apparatus suitable for pumping semi-liquid materials such as freshly mixed concrete or the like, comprises a drive mechanism operable to effect charging motion to a reciprocating pumping member at one rate of speed and discharging motion at a rate substantially higher than that of the charging motion. Pump cylinders C1, C2, C3, Figs. 1-3 and 10, are supplied with concrete from a hopper 16 through inlets 23, 24, 25 respectively, from which cylinders the concrete is forced by pistons 43 through outlets 28 into a common receiver 29 converging to a single delivery pipe 34 of approximately the same diameter as the inlets 23 to 25, cylinders C1 to C3 and outlets 28. The pistons 43 are driven through connecting rods 44 and bars Bl, B2, B3 each of which is provided with an upper lug 55 and a lower lug 57, respectively associated with pins 56 and 58 held between adjacent plates 48 of an upper clockwise rotating set and plates 50 of a lower set rotating at the same speed in the same direction as the upper set. The lugs 55 and 57 are thus periodically engaged by their associated pins 56 and 58 to cause the bars B1, B2, B3 to reciprocate between guide rollers 52, 53. The pins 56 are twice the distance from the centre of rotation of the set of plates 48 as the pins 58 are from the centre of rotation of the set of plates 50, so that on rotation of both plate sets, the time taken for the discharge stroke of each piston 43 is half of that taken for its suction stroke. The relative angular positioning between the respective groups of pins 56, 58 is such as to cause each piston 43 in turn to perform its discharge stroke when the other two are performing parts of their suction strokes. Flat rotary sector-shaped valves 36, 37 control the opening and closing of the inlet and outlet ports respectively, in synchronism with the operation of pistons 43. This is accomplished by arranging that the valve 36 (Fig. 2) opens two inlet ports simultaneously whilst the valve 37 (Fig. 10) opens only one outlet port, and by driving the valves 36, 37 at twice the speed of rotation of the plates 48, 50. A shaft 67 drives the valve 36 through gearing 68, 72, chain 75 and pinions 80, 81, the valve 37 through helical gears 70, 71, and the plates 48, 50 through reduction gearing 68, 66, 63, 64. The lower face of the valve 36 may be part-conical and rotate in a conical seating and the outer face of the discharge valve may be part-conical. The pump may have more than three cylinders providing that the travel time of a piston discharge stroke is approximately equal to the travel time of a piston suction stroke divided by one less than the number of pumping cylinders. In an alternative embodiment, Figs. 11 and 13, three cylinders Cl, C2, C3 are arranged with their axes parallel and in the same horizontal plane. Each cylinder has a hydraulically-actuated piston 99, a hydraulically-actuated gate valve V1, V2, V3 and a discharge pipe D1, D2, D3. The discharge pipes D1 to D3 converge to a common delivery pipe 90. When a piston, such as C1 reaches the end of its discharge stroke a driver 125 at the end of a rod 113, common to pump piston 99 and drive piston 114, strikes an abutment 127 and shifts a spool 123 of a control valve 117 to the right to connect a conduit 133 with a conduit 130 carrying high pressure fluid from a pair of pumps P1, P2 each having the same output. The high pressure fluid then flows through conduit 133 to a gate valve control 104 to move a piston 105 and the gate valve V1 to the left and thereby close the discharge pipe and open an inlet 94. Connections 128, 129 cause a spool 124 of a control valve 120 to move to the left to allow high pressure fluid to be delivered through ports 141, 136 and conduit 137 to the front of the drive piston 114 in a cylinder 109, to cause the piston 99 to commence its suction stroke. At the same time as the piston 99 in cylinder C1 reaches the end of its discharge stroke, the piston 99 in cylinder C2 reaches the end of its suction stroke and its driver 125 strikes an abutment 126 to cause reversal of the gate valve V2, the spool 123 in control valve 118 and the spool 124 in control valve 121. Reversal of the latter spool disconnects the high-pressure fluid delivery to the conduit 137 associated with drive cylinder 110, and connects conduit 143 with pump P1 for delivery of the high-pressure fluid through conduit 142 to the port 141 of control valve 120. The piston 99 in cylinder C2 will then commence its discharge stroke and will be driven at approximately twice the speed of the other two by the fluid exhausted from their hydraulic cylinders 109, 111 through a common conduit 115, the fluid exhausted from in front of the piston 114 in the cylinder 110 being passed to a reservoir 138. In an alternative hydraulic circuit, Fig. 16 (not shown) high pressure fluid from a single pump supplies a line associated with all three spools 124, each of which, at the commencement of the discharge stroke of the associated pump piston 99, takes up a position whereby the high pressure fluid is allowed to pass to the back of the drive piston 114 to drive the piston 99 forward, or, at the commencement of the suction stroke of the piston 99, takes up a position whereby the high pressure fluid is blocked off and fluid from behind the drive piston 114 is allowed to pass to a reservoir. The fluid exhausted from in front of the drive piston 114 of the discharging piston 99, is divided into two equal flows which are passed to the front of the other two drive pistons 114 for driving their pistons 99 on their suction strokes.