GB939507A - Wind motors and pumps driven thereby - Google Patents

Abstract

939,507. Wind-motors; centrifugal governors. DOWTY ROTOL Ltd. Dec. 28, 1961 [Jan. 12, 1961], No. 1341/61. Classes 57 and 110 (3). [Also in Groups XXVIII and XXIX] A pumping device comprises a wind-motor, a fluid pressure pump connected to be driven by the wind-motor, the wind-motor having blades the pitch of which is adjustable and means responsive to a delivery condition of the pump such that when the delivery condition attains a predetermined value the pitch of the blades is changed. The unit shown is suitable for mounting on an aircraft and may be retracted into the fuselage when not in use. The unit comprises a wind-motor having angularly adjustable blades 11 mounted on a hub 13 which is connected by means of a shaft 19 to a fixed displacement swash type pump 20. The blades 11 are pivotally mounted at 12 and are adjustable by means of a piston 14 which is disposed within a cylinder the piston rod 16 being connected by suitable linkages to the blades. Fluid may be supplied to either side of the piston 14 under the control of a centrifugal governor device in the form of a spool valve 35, movement of the piston to the left increasing the pitch of the blades and movement to the right decreasing the pitch of the blades. The pump comprises a cylinder having a number of axial bores in which are disposed plungers 23, the plungers being connected to a ring 24 which bears against the fixed swashplate 25. The pump takes its suction from a reservoir 27 through line 26 and delivers through outlet 28, through an unloading valve 30 to the duct 29. A non-return valve 31 is disposed in the line 29 and an accumulator 32 is connected to the line downstream of the non-return valve. A high-pressure relief valve 34 is connected to the duct 29, the relief valve connecting the duct 29 to the duct 62 and so to the passage 61 in the event of excess pump pressure. The pump also supplies fluid at pump delivery pressure through the ducts 49 and 50 from which it may flow under the control of spool valve 35 to the ducts 56, 57 leading to the spaces 58, 59 at either side of the piston 14. When the unit is retracted out of use, the spring 47 of the centrifugal governor device 35 urges the spool valve radially inwardly so that the land 39 is disposed radially inwardly of the duct 57, the pitch of the blades 11 being set in the coarse position. As the unit is moved into the airstream, the wind-motor commences to rotate so driving the pump which delivers fluid under pressure through the orifice 30c of the spool 30b of the unloading valve 30 into the supply duct 29. The valve 30 is arranged to operate at starting so as to off-load pressure by relieving past the member 30a to the drain line 61. With increase in pump delivery pressure, the spool 30b is moved downwardly so as to increase the loading of the spring acting on the valve member 30a. With further increase in speed of the wind-motor and pump, the spool valve 35 starts to move radially outwardly under centrifugal force against the loading of the spring 47. During this movement of the spool valve the land 39 passes over and radially outwardly of the duct 57 so that pressure fluid from the duct 50 is cut off from the duct 57 and now passes through the duct 56 to the chamber 58 at the left hand side of the piston 14 which thereupon moves to the right and adjusts the blades 11 to a finer pitch. The chamber 59 is now placed in communication with a drain passage 52 via duct 57 and annular chamber 43. Upon further increase in wind-motor speed, the spool valve moves further outwardly until the land 39 occupies a position across the duct 50, the parts being so dimensioned that pressure fluid then flows through both ducts 56, 57 and the piston 14 is then held stationary. If the rotational speed now increases beyond this first datum speed, the spool valve 35 moves further outwardly causing pressure fluid to pass through the duct 57 thereby resulting in increased blade pitch. If the speed should decrease, the converse occurs. When the pump delivery pressure attains a predetermined value, say 3000 p.s.i., the relief valve 34 opens and pressure fluid passes by way of ducts 62, 61 and 60 into the space above or radially inwardly of the spool valve 35 and the spool valve therefore moves radially outwardly whereby pressure fluid is caused to flow through the duct 57 so that the piston 14 acts to increase the pitch of the blades 11. As the speed falls off, the spool valve moves radially inwardly until the land 39 again registers with the duct 50, this being a second datum position, and the unit now runs at constant second datum speed with the increased blade pitch. When the demand increases the pressure at the relief valve 34 will fall and the valve 34 will move to close off the duct 62 and the resulting radially inward movement of the spool valve 35 will cause the blades 11 to be adjusted to reduce pitch.