Patent GB-191111818-A (GB)
Filed: 1911-05-16
Granted: 1912-06-17
Abstract: 11,818. Humphrey, H. A., and Rusdell, W. J. May 16. [Cognate Application, 13,342/11.] Free-piston pumps; actuating by gas-engines; regulating delivery of two or more combined pumps. - In an internal-combustion pump of the Humphrey type, without a fly-wheel, which raises or forces liquid by the energy of expansion of an ignited combustible mixture, the liquid reciprocating mass is substituted entirely or in part by a solid mass or linked solid masses, the whole being capable of acquiring momentum sufficient to limit the velocity of the liquid through the valves to that required in practice, so that the masses reciprocate freely and continuously without control otherwise than by work done or energy stored, or both, at each stroke, the momentum aiding the compression of the combustible mixture or a constituent thereof before ignition to the desired pressure in a combustion chamber by an inward stroke of the reciprocating masses towards such chamber. The simplest apparatus for carrying out this process is shown in Fig. 1, in which the solid piston 2 is forced by the explosion of combustible mixture in the chamber 1. The suction and delivery valves are shown at 6 and 8 respectively, and a chamber 9 contains air which is compressed by the outward movement of the liquid, and which serves to effect the return movement of the piston. The capacity of the chamber 9 may be varied by including or excluding the auxiliary chambers 15, 16, and the expansion of the air may be limited by the adjustable stop 11, which is struck by the float 10. Modifications of this pump are described, in which (a) the piston 2 consists only of a small mass next to the combustion chamber, the remainder of the reciprocating mass being liquid; (b) the piston is partly hollow, the end being closed by a smaller sliding piston, enclosing an air buffer; (c) the air buffer in (b) is compressed at a predetermined point in the stroke by a fixed projection on the casing which is struck by the smaller piston of the combined moving mass; (d) the piston is divided into two parts between which is a fixed quantity of liquid which is forced to move with the pistons; (e) the piston is made with two diameters so that liquid can be pumped against a greater head; (f) the piston is made in three diameters, liquid being forced by differential action, the smaller part projecting into the delivery chamber so that the return of the piston is effected by the delivery head; (g) the air buffer only comes into action when the piston closes a port opening into the atmosphere. In the form shown in Fig. 10, the engine and pump portions are separated. The piston 17 of the double-acting two-cycle engine is connected with a piston 30 for supplying scavenging air or combustible mixture, or both, to the engine, and with a piston 31 working in a cushion cylinder. Two pump elements of ordinary form are used, one at each end of the chain of pistons. In the form shown in Fig. 12, the piston 17 and liquid column 42 move vertically, compressing air in the space below the diaphragm 43 and forcing liquid into the reservoir 41. A modification is described in which the reciprocating mass is entirely solid, and there is no diaphragm, the return of the piston being effected by its own weight. Fig. 13 shows a modification for producing a continuous flow. The piston 17, in the combustion chamber 1, reciprocates with a liquid column 44 which compresses air in a cushion above 45. The exhaust valve 46 opens by its own weight, and is closed by the impact of the piston. Valves 49, 50 admit gas and air by suction, the mixture being compressed after the layer of burnt products has been expelled and the valve 46 closed by the upward movement of the piston. The momentum of the water in 55 is sufficient to enable the flow to continue in the same direction when the piston moves upwards, the water entering the valves 54 and following the moving column. A modification, Fig. 16, is described in which the piston is placed in the middle of the reciprocating liquid, and the combustion chamber contains a vertical diaphragm so that scavenging air may be introduced on one side while the burnt products are being expelled from the other side, the next two strokes admitting and compressing combustible mixture. The space corresponding to 45, Fig. 13, has a valve at its upper end leading to a chamber for scavenging air, so that the water column, in moving upwards, supplies the scavenging air, some of which then acts as a cushion in the upper part of the vessel 45. This vessel may have a vertical diaphragm, so that both air and combustible mixture may be supplied, one on each side. A modification is described in which the suction takes place on the outward stroke, energy being also stored, while delivery takes place on the return stroke by the energy of the cushion. This type is suitable for large suction lifts and small delivery pressures. In another modification the masses are made to move without being rigidly connected together. They are connected through the medium of a bell-crank lever which carries part of the mass in the form of a pendulum bob. A governing- device is shown by which the moment of inertia of the system is varied by varying the radius of action of this weight. Fig. 23 shows a form of governing-device which enables the length of the stroke and the total energy stored to be kept constant. The solid piston 21 compresses air in a space 24 and also, through the medium of the liquid, in the space 9. The space 24 can be varied in volume by the rotary valve 101 which communicates with the atmosphere. A similar valve 100 varies the volume of the cushion 9 by connecting it with one or more of the auxiliary vessels 15<b>, 15<c>, 15<d>. The pressure of the delivery liquid acts upon the piston in the device 103, and by means of a rod 102 moves both valves 101, 100 simultaneously, so that the space 24 is enlarged and 9 is decreased, or vice versa. Assuming that the space 24 is decreased, less energy will be stored there, and more in the cushion 9, while liquid delivery will begin later. If the delivery pressure is smaller, more energy will be stored in 24 and less in 9. A governing-device is described by which varying lengths of stroke operate to control the pump. If the piston moves beyond a predetermined point, it strikes a small spring-controlled piston whose motion is transmitted by liquid in pipes to a device which throttles the fuel supply and opens a throttle in the liquid suction pipe. The same device may be operated by the varying velocity of liquid in the play pipe acting on a vane. In another governing-device, a trailer carried by the piston-rod depresses a pivoted lever at the ends of the stroke, the amount of depression depending on the position of the trailer relative to the fulcrum of the lever. The lever actuates the fuel throttle of the engine. A device is described for stopping the pump if one or more of the suction or delivery valves should fail to close at the proper time. The end of a small rod is made to describe an indicator diagram for the pump, and upon any change in the shape of the diagram from the normal the rod opens the ignition circuit. Fig. 27 shows a device by which the throttling effect is made to persist for a short time. On the outward movement of the piston-rod 115, the cam 127 moves the rod 128 and throttle 124, drawing in liquid freely through valve 136<a> of the dash-pot 129. The piston slowly falls as liquid escapes through the cock 136, thus allowing the throttle to open slowly. A device is described for connecting an auxiliary pump to the main pump, giving it a variable stroke, and thus varying the total delivery. Fig. 29 shows a device by which the pump is kept in operation in the event of a feeble explosion or a missfire. Auxiliary suction and delivery valves 155, 154 are provided, normally pressed open by springs but kept shut by the lever 160, which is kept in position by the velocity of the liquid in the delivery pipe 156 acting on the vane 157. If the velocity of the liquid falls below the normal, the valves 154, 155 open, so that the delivery water assists in the compression of a fresh charge, and thus enable the pump to continue in motion till normal conditions are re-established. Some lost motion may be introduced so that normal fluctnations of velocity may be permitted in the pipe 156.