GB1081047A - Improvements in and relating to methods and apparatuses for the regulation of a compressor assembly - Google Patents

Abstract

1,081,047. Fluid-pressure servomotor systems. HOERBIGER VENTILWERKE A. G. Nov. 19, 1965 [Nov. 24, 1964], No.49367/65. Heading G3P. [Also in Division F2] In a compressed air system the compressor is unloaded in stages in response to the. pressure difference across an adjustable throttle in the delivery line to maintain the upstream pressure of the throttle slightly higher than the downstream pressure, the latter being the desired operating pressure of the apparatus supplied by the compressor. As shown, a double-acting compressor 1 has delivery valves 4, 5, suction valves 2, 3 with unloading cylinders 17, 18 and clearance spaces controlled by units 19, 20. The delivery line 7 to consuming apparatus 13 includes a feed tank 8, a discharge tank 11, a manually controlled throttle 9 and a further throttle 10 operated in response to downstream pressure by a transmitter 14 and pilot valve 15. The pressure difference across the throttles is applied via lines 32, 33 to a piston valve 16 having a supply port 21 connected by line 27 to the delivery line, ports 22-25 connected respectively to units, 19, 17, 20, 18, and an exhaust port 26. In operation, when the compressor is first started the piston (40) of valve 16 Fig. 3 (not shown) is urged to the left by spring (48) to connect ports 22-25 to exhaust, the compressor thus delivers its maximum output to apparatus 13. When the pressure in the system reaches a predetermined value, transmitter 14 initiates closure of throttle 10, and when the pressure upstream of the latter reaches a predetermined value piston (40) is moved to the right to connect ports 21, 22, thereby actuating unit 19 to partially unload one end of the compressor. Further increase of the upstream pressure causes movement of piston (40) to progressively connect port 21 with ports 23-25, thereby causing further unloading of the compressor. The unloading may be in stages of 25% of the maximum compressor delivery, each stage corresponding to the engagement of a groove in piston (40) with a detent (41). In modifications, tanks 8, 11 and throttle 9 are omitted; spring (48) may also be omitted if the left-hand end of piston (40) is of a larger effective area than the right-hand end. The piston (40) may alternatively be actuated by a single doubleacting piston or diaphragm. In Fig. 2 (not shown), a similar compressor supplies two consumers (13', 13") via lines (12', 12") having throttles (10', 10") controlled by transmitters (14', 14"), check valves (34, and 35) being provided to transmit the higher of the two downstream pressures to valve (16) so that the latter operates to maintain an upstream pressure that is slightly higher than the highest of the two downstream pressures. A vent valve (36), the downstream side of which can lead to the compressor section, permits ventilation of valve 16 in the event of decreasing consumer pressures.