Patent GB-529720-A (GB)
Title: Improvements in or relating to oil well pumping machinery
IPC: F04B47/04
Filed: 1939-04-25
Abstract: 529,720. Hydraulic transmission of power. ARMSTRONG, J. J. V. (Vickers, Inc.). April 25, 1939, No. 12365. [Class 69 (ii)] In an oil-well pumping-system of the kind comprising a reciprocating motor for a wellpump, an accumulator, and a power-pump for directing liquid alternately to the reciprocating motor and accumulator in a closed system, means for replenishing the system is automatically operated when, on account of leakage, the reciprocating motor or the accumulator piston makes a prolonged movement. The apparatus shown in Fig. 1 comprises a pistonmotor 30 for the pump-rod 42, a tank 48, a rotary pump 34, an accumulator 32 connected to an air-vessel 33, and valves 63, 77, 78, the valve 63 being pilot-operated under control of the valves 77, 78. The valve 63 slides in a bore 60 formed in a block 59 and having ports communicating through pipes 67, 69, and 55, 56 with a port 43 in the motor-cylinder 31, the accumulator 32, and the inlet and outlet of the pump 34 respectively. The valve 77 slides in a bore 75 formed in a block 37 and having ports communicating through pipes 83, 84, and 79 with the accumulator 32, tank 48, and a check-valve 81 at the bottom of the bore 60. The valve 77 is operated by a bell-crank 86 arranged in the path of cams 88, 89, 90 on the rod 51 of the accumulator-piston 50. The valve 78 slides in a bore 76 formed in the block 37 and communicating through pipes 67a, 80 with the pipe 67 and check-valve 81a at the top of the bore 60. The bores 75, 76 have communicating cross-passages 92 ... 95. When the pistons 50, 30 commence to descend, the valve 77 is in raised position, liquid can pass through the pipes 83, 79 and valve 81, the valve 63 rises, and the pump 34 delivers liquid through the pipe 69 to the accumulator. Liquid above the valve is returned through a needle-valve 82a and the pipes 80, 84 to the tank. Near the end of the down-stroke of the pistons 30, 50, the cam 89 rocks the bell-crank 86, the valve 77 is depressed, the pipe 79 is cut off, liquid is delivered through the pipe 80 and valve 81a, and the valve 63 is depressed. Liquid beneath the valve is returned to the tank through a needle-valve 82, the pipe 79, an axial hole in the valve 77, and the pipe 84. On descent of the valve 63, the pipes 55, 56 are gradually connected to the pipes 67, 69, the flow of liquid in the system is reversed, and the pistons 30, 50 are raised. When the pistons approach the top of their stroke, the cam 88 rocks the bell-crank 86, the valve 77 is again raised, and the cycle is repeated. When leakage occurs in the system, the piston 30 descends abnormally and closes the port 43, the pressure in the pipes 67, 67a falls, the valve 78 is depressed by pressure in the passage 92, and communication between the pipes 83, 80 is prevented. When the valve 77 is depressed by the cam 89, the valve 63 remains in raised position, and the pipes 79, 80 are connected through the pipe 84 to the tank. Liquid is then drawn through a valve 58 and pipe 57 by the pump 34 to replenish the system, the piston 50 descends until the cam 90 rocks the bell-crank 86, and the valve 77 is depressed further to effect delayed reversal of the liquidsystem. Liquid then passes through pipes 83, 80, the valve 63 is raised, and the normal cycle is resumed. The cylinder 31 is provided with a valve 47 for releasing liquid trapped beneath the piston 30, and a valve 45 for admitting liquid when the piston rises after replenishment of the system. In a modification, the pump 34 and valve 63 are replaced by a variable-displacement pump 100, Fig. 6, comprising a movable head 101 for varying the displacement and direction of flow. One of the pump openings is connected to the pipes 67, 57, and the other opening 102a communicates with a dome 102 which is connected by a pipe 69a to the accumulator 32. The movable head is shifted by means of a rod 103 having end-pistons mounted in cylinders which communicate through pipes 79a, 80a with the valves 77, 78. The cams 88, 89 operate the valve 77 and thereby initiate movement of the head 101 in one direction or the other to reverse the flow of liquid in the system. When the piston 30 closes the port 43, the valve 78 is depressed, and the pump draws liquid through the pipe 57 and valve 58 to replenish the system. The normal cycle is resumed when the cam 90a becomes effective. The apparatus shown in Fig. 11 comprises large and small pumps 129, 130 and a pilot-pump 131 driven by a motor 126, an accumulator 120, valves 77a, 78b, 134 (acting during normal cycles in a manner similar to the above-described valves 77, 78, 63), and a pump-selector valve 133. The valve 133 can be manually adjusted to permit employment of either the pump 129 or both pumps 129, 130 during normal cycles, and is automatically adjusted to cause the pump 130 to replenish the system. When the pistons 30 and 121 reach the top and bottom of their strokes, a cam 88a on the accumulator piston-rod 123 rocks a bell-crank 86a, the valve 77a is raised, and liquid passes through a pipe 141 and check-valve 81a to depress the valve 134. Liquid flows also through a passage 153 to depress the valve 133, thereupon the pistons 30, 121 begin to fall and rise, the liquid-paths being as follows: Liquid from the cylinder 31 passes through a pipe 136 and around the valves 134, 133 to the pump inlets 146, 147, and is delivered by the pumps through the pump-outlets 148, 149 and a passage 152, around the valve 134 and through a pipe 138 to the accumulator; liquid from the pipe 136 flows also through a passage 153 and pipe 137 to hold the valves 78b, 133 in raised and depressed position. The valve 133 rests on a cam 135 which is normally set in the position shown, to permit operation of both pumps 129, 130. By adjustment of the cam, the valve is permitted to assume a lower position and the pump 130 is byepassed. When the pistons 30 and 121 reach the bottom and top of their normal strokes a cam 89a depresses the valve 77a, and the valve 134 is raised by liquid which passes from the pump 131, through a pipe 140, around the valves 77a, 78b, and through a pipe 142 and check-valve 81. Thereupon, the pipe is connected through the passage 145 to the pump-inlets 146, 147, the pipe 136 is connected through the passage 152 to the pump-outlets 148, 149, the pistons 30, 121 begin to rise and fall, and the cycle is repeated. When leakage occurs in the system, the piston 30 descends abnormally and closes the port 43, the pressure in the pipes 136, 137 and passage 153 falls, the valve 78b is depressed by a spring 144, and the valve 133 is raised by the pressure in a passage 154. Thereupon, the pump 129 is byepassed, the inlet 147 is closed, and the pump 130 draws liquid through a pipe 157 from the tank 124 and delivers it to the accumulator to replenish the system. A cam 90a then depresses abnormally the valve 77a, pilot-pressure passes from the pipe 140 around the valve 78b to the pipe 142, and the valve 134 is raised to reverse the flow in the system. Valves 160, 161, 168, 169 prevent development of excessive pressures. An overflow pipe 163 from the pump 131 leads to a chamber 164 provided with cooling-fins 165. In a modification, Fig. 16 (not shown), a single valve 133a performs the functions of both the above-described valves 133 and 78b. Specification 529,770 is referred to.