Patent GB-190405958-A (GB)
Title: Improvements in and connectd with Air and other Gaseous Fluid Compressors, Blowing Engines, Motors, and Pumps.
Inventor: COOMBS JAMES ALGER
Filed: 1904-03-11
Granted: 1905-03-11
Abstract: 5958. Coombs, J. A. March 11. Steam pumps ; governing or controlling pumps. - Slide valves having either rectilinear or circular motion are moved by pistons which are operated by fluid pressure, or by spring mechanism, when detents, normally locking the valves, are released periodically by cam gear ; the lead of the valves of a compressor or pump is altered automatically, through the cam gear, by pressure in the delivery main imparting a step - by - step motion to a weighted piston, which is connected to means for varying the point of operation of the detent-actuating cams ; and the device for altering the lead may be applied for governing the driving- engines of compressors &c. by throttling the motivefluid supply. Fig. 1 shows the general arrangement of valve gear for a high-pressure compressor. Motive fluid for operating the valve-actuating pistons in the cylinders e is distributed by large slide valves, which are operated through a lostmotion device consisting of a cylinder k' on the ends of the valve-rods i<2> and of double-ended plungers working therein and connected to the piston-rods e<2> by arms j. The valves are moved by the air compressed between the plungers and the ends of the cylinders. As the piston-rods and valve-rods move in the same direction, the ports are crossed; they are formed by connected drilled holes, and are fully opened to exhaust only. The pistons imprison some of the motive fluid towards the end of each stroke, and are thereby cushioned. Leather &c. cushioning-pads at the cylinder ends may be backed by springs. The piston-rods, which pass through dash-pots h, are normally held by detents o' pressed upwards by springs to engage projections p on carriers p<1>. The release of the detents is effected periodically by a shaft u, cams v, levers q, and a rocking shaft carrying yokes q<3> fitted into slots in the detent spindles o<5>. In the case of a large vertical blowing-engine, the springs for actuating the detents are replaced by fluid-pressed pistons, which are linked to the levers q. Gridiron slide valves are arranged within the cylinder covers. Fig. 12 shows a delivery valve c working on the outer side of a port provided with a face-plate c' ; the valve is pushed against its seat by spring-pressed rollers c', but is capable of a small lift therefrom. The inlet valve works on the inner side of its cylinder port, and is surmounted by a perforated guardplate furnished with wave or other springs, to permit of a similar small lift. The valves are either connected directly to the piston-rods e', or are operated through oscillating spindles, slotted discs, and sliders carrying guided pins fitting in the valve ends. Fig. 29 shows the device for altering the lead of the valves. Compressed fluid from a delivery main forces upwards the accumulativelyweighted ram n, thereby rising rods r' carrying a bridle connected by a ring with an outer sleeve on the cam shaft u, Fig. 1. The sleeve is provided with pins, one of which engages a vertical slot in a sleeve keyed to the cam shaft, the other working in an inclined slot in a loose sleeve on which the cam is mounted ; the movement of the ram consequently varies the angular position of the cam on the shaft. The ram may be provided with two sets of accumulative weights one above the other, and the weights may be arranged on separate supports so that they become bunched when lifted. Fig. 30 shows a device in which pistons w<7> connected by ruds w<11> to the main valves are moved by compressed springs when the detents holding the rods have been withdrawn. A cam x, by means of a roller w<6>, link w<5>, and connected pivoted levers w<3>, compresses one and extends the other of the springs w connected to the piston, which works in a dash-pot.