Patent GB-222106-A (GB)
Title: Improvements in compressor unloading mechanism
IPC: F04B25/00
Filed: 1924-09-03
Abstract: 222,106. Worthington Pump & Machinery Corporation, (Assignees of Riesner, M.). Sept.. 19, 1923, [Convention date]. Fluid-actuated valves employed in the unloading of compressors having multiple unloading devices reverse the operation of one of the unloading devices to bring it into unloading and loading position succcessively during the complete unloading of the compressor. A single clearance chamber may be provided, combined with means for keeping the suction valves open. Fig. 3 shows a doubleacting cylinder having inlet valves D, D<1>, at each end, a clearance space F the valve b of which is controlled automatically, at one end, and clearance spaces G controlled by hand valves 17 at the other end. The valves D, D<1>, b are held open when the desired receiver pressures are reached by pressure fluid from the receiver or other source acting upon them through pipes 2, 3, 1. The section valves are held open by fingers 11, Fig. 8, on a slide 10 moved against a spring by the fluid pressure acting on a piston 12. The clearance valve b, Fig. 3, is actuated by a piston 14 subject to the fluid pressure tending to open it against a spring end, in the case of compound compressors, against the intercooler pressure admitted through a pipe 16. Increase of receiver pressure first opens the clearance valve b, then holds the suction valve D at the crank end open then releases this valve and holds the other inlet valve D<1> open, and finally holds both valves open. The clearance spaces G are used to regulate the maximum capacity of the cylinder. The supply of pressure fluid for unloading is controlled by a valve c, Fig. 5, actuated by a piston 24 controlled by a pilot valve d having connections 29, 30 for the supply and exhaust of pressure fluid. This pilot valve is lifted by a lever 31 linked to a weighted lever 33 bearing on a. diaphragm 35 subject to the receiver pressure, admitting pressure to the left end of the piston and subjecting the right end to exhaust through passages 27, 26. The fulcrum of the lever 31 is altered' after each such rise by its situation on a bell crank 37, Fig. 4, connected through a link 38 with a bell crank 39 the free arm of which carries a roller resting on a stepped slide 40 connected to the rod of the piston 24, and the pilot valve is thus returned to its neutral position. The successive movements of the valve effect the desired connection of the pipes 1, 2, 3 with the pressure fluid space 19 surrounding the valve or with an exhaust pipe 21. Fig. 9 shows an alternative device for controlling the fluid supply to the valves, comprising a cylinder open through a pipe 20 and ports 43, 44 to the receiver pressure and exhaust respectively and containing a grooved piston valve e capable of opening the receiver pressure to pipes 1, 2<a>, 3<a>, and 4<a>, the three latter pipes opening into a chamber 46 containing a. valve f moved by a, piston acted upon by a spring 47 and in certain positions by pressure fluid admitted through pipes 3<a>, 4<a>; the motion of the valve connects the pipe 2<a> either to the pipe 2 or to an exhaust pipe 49. By-passes 60 and valves p, q allow some of the unloading devices to be cut out of operation. Fig. 10 shows a compound duplex pump comprising high and low pressure cylinders A<1>, A<2>, B<1>, B<2> in pairs having common piston rods connected to the same crank shaft, the clearance chambers being at the crank end of one set and the head ends of the other set. A single regulator may be used for all the cylinders or separate regulators.