GB1278825A - Pump, fan or turbine with variable blade rake - Google Patents

Abstract

1278825 Mixed-flow pumps and fans; turbines NATIONAL RESEARCH DEVELOPMENT CORP 8 April 1970 [10 April 1969] 18503 /69 Heading F1C and FIT In a pump, fan or turbine in which blades mounted on a rotor boss within a part-spherical housing may be varied in rake angle so as to vary the flow between predominently axial and predominantly radial, blade supports mounted in the boss are each rotatable about a blade support axis intersecting the rotor axis and at an angle to the rotor axis which lies between two extreme limits of adjustment of the rake angle, each blade support defining a blade pivot axis intersecting the rotor axis and at an angle to the blade support axis, means operable externally of the machine for rotating the blade support relative to the boss about the blade support axis, planetary gear means comprising a gear fast with the blade and concentric with the blade pivot axis and a gear centered upon the blade support axis and means for making the latter gear fast with the boss, whereby, on rotation of the blade support about the blade support axis, the pitch angle of the blade bears a predetermined relationship to its rake angle. Each rotor blade 6, Fig.2, of a pump is pivotally mounted on a blade support 14 which in turn is pivotally mounted on a rotor hub 25, the blade axis 36 and the blade support axis 17 intersecting the rotor axis at a common point 37. Adjustment of each blade 6 between the full-line position in which the flow is predominantly axial and the dotted position 19, see also Fig. 3, in which the flow is predominantly radial can be effected while the pump is running by a hand wheel 58 which causes longitudinal displacement of a non-rotating pushrod 55 passing through the hollow shaft 5 of the rotor. The push-rod 55 engages a cam block 50 through flanges 66, 67 to displace the cam block along guide bars 51, 52 carried by the rotor hub. The cam block 50 is engaged by cam followers 48, one for each rotor blade, which effect rotation of the blade supports 14 about their axes 17 through gearing 44, 42. A hollow bush 29 forming a bearing for the spindle 32 of each blade support 14 is formed with a pinion 40 which meshes with an idler pinion 34 carried by the blade support, the idler pinion in turn meshing with a pinion 38 fast with the blade spindle 35, the pinions forming a planetary gearing which, as the blade support is turned to adjust the blade rake angle, causes the blade to turn in the opposite direction relative to the blade support so that the blade pitch angle remains unaltered. The tooth ratio of the pinions 38, 40 may differ from unity to cause the pitch angle to increase or decrease instead of remaining unaltered. In another arrangement, Fig.7, the gear 44 is carried by a central shaft 81. Gearwheels 82, 83 on the rotor shaft 5 and shaft 81 are connected via respective pinions 84, 85 to a ring gear 86. A normally stationary ring 89 carrying the pinion 85 can be rotated to effect the blade adjustment. In a further embodiment, Fig.6 (not shown) the gear (44) is driven, for adjustment of the blades, by an electric, hydraulic or pneumatic motor carried by the rotor hub.