Patent GB-190228406-A (GB)
Title: Improvements in or relating to Engines and Pumps.
Inventor: BOULT ALFRED JULIUS
Filed: 1902-12-23
Granted: 1903-12-23
Abstract: 28,406. Boult, A. J., [Ortenbach & Vogel]. Dec. 23. Steam pumps ; ; hydraulically-actuated pumps diferential pumps.-Consists chiefly of steam-distributing means for pumping and other engines, and of means for reducing the load towards the end of the stroke so that expansive working may be used in a direct-acting pump. Fig. 1 shows a form of direct-acting pump adapted for non-expansive working. The small pistons 57, 58, which are half the area of the main pistons, control the communication of the passages 59, 60 with the suction 66 and delivery 64, so that the small piston of one pump acts as the valve of the other. Further, by the use of these differential pistons, the pumps force on both strokes. In order to allow of lap on the pistons 57, 58, the distributing-valve gear is set so that, while one of these pistons is covering its port 59 or 60, the other pump is stationary. Fig. 3 shows a section through one of the barrels of a duplex direct-acting pump adapted for exparsive working. The valve pistons are made in two parts, such as 58, 76, the one slightly less and the other slightly greater than half the area of the main piston 54, and each part working in a corresponding part of the barrel. In both pumps the smaller piston is nearer the delivery than the larger, the result being that, towards the end of the stroke, the load is reduced to an extent corresponding to the difference between the areas of the pistons 76, 58. Relief valves 77 are provided to allow the escape of surplus liquid, due to the entry of the valve pistons of one pump into their barrels when the other pump is stationary. The means just described for varying the load during the stroke are also applicable to high-speed crank-driven pumps, with the modification, however, that the larger pistons 76 are nearer the delivery than the smaller. The load is then increased during the second part of the stroke to provide the force required for bringing the reciprocating parts to rest. If the pump shown in Fig. 1 is crank-driven, the relief valves 77 may be used for the same purpose as described above, and, in any case, to allow of the escape of air into the air vessel. In order to allow the use of piston-ring packing, the barrels of the pistons 58, 76 may be made long enough to take the pistons throughout their stroke, communication with the passages 59, 60 being made through oblique ports in the barrels. By substi. tuting for the steam pistons and cylinders of the pump shown in Fig. 1 a set of pistons and cylinders exactly similar to those of the pump, a pump actuated by liquid pressure is obtained. In the motor end the pressure liquid enters at the opening corresponding to 66 and exhaust at that corresponding to 64, and is controlled by the pistons corresponding to the pistons 57, 58. The steamdistributing means comprises a single valve for each piston and having the same motion as the piston. The valves are formed with passages cooperating with connecting passages in the casing. The steam in entering and leaving the cylinders passes through both valves, and each valve acts as expansion and compression valve for its own engine and admission and exhaust valve for the other engine.