GB1117479A - Improvements in and relating to non-positive displacement compressors - Google Patents

Abstract

1,117,479. Axial-flow compressors. BROWN BOVERI & CO. Ltd. Aug. 5, 1965 [Aug. 7, 1964], No.33555/65. Heading F1C. [Also in Division G3] In a non-positive displacement compressor, e.g. an axial-flow compressor, having adjustable stator blades 3, or adjustable rotor blades, a probe 11 for detecting error in the flow angle of the working fluid when the pumping limit is reached is adjustable relative to the stator to compensate for variations in flow angle relative to the probe due to blade adjustment. Detected error results in opening of a diaphragm actuated valve 30 to relieve the pressure of oil supplied at 31 and thereby to open a piston actuated blow-off valve 32, 33. The blades 3 may be adjusted in accordance with a pressure difference in the compressor or with delivery pressure by a bellows 24 which through a valve 25 relieves the pressure of oil supplied at 26 and acting on a piston 27 which controls devices 28 for rotating the blades and probe. Coupling between probe and blades may be mechanical, hydraulic, pneumatic or electrical. The blades and probe may be adjusted through gearing having the same or a different ratio, Fig. 1 (not shown), or the probe may be adjusted through a cam-actuated means, Fig. 2 (not shown). Since the flow angle varies along the length of each blade, the variation of flow angle relative to the probe due to blade adjustment may be compensated by radial movement of the probe. The probe may be a yawmeter, Fig. 4 (not shown), with two or more inlets. Alternatively it may be formed by a body having two opposed pressure fluid outlets controlled by a common leaf-spring subjected to the main flow, Fig. 5 (not shown), or formed by a leaf-spring subjected to the main flow and fitted with strain gauges.