Patent GB-1074736-A (GB)
Title: Wind motors
Inventor: ELMES ROBERT TERENCE
IPC: F03D7/02
Filed: 1964-09-09
Abstract: 1,074,736. Wind motors. DOWTY ROTOL Ltd. Aug. 31, 1965 [Sept. 9, 1964], No. 36919/64. Addition to 987, 032. Heading F1T. [Also in Division G3] A wind motor as claimed in Specification 987, 032 comprises a two bladed rotor 12, Fig. 1 (not shown), mounted from an aircraft on a retractable leg (20). The pitch of the blades 13 is controlled by a hydraulic mechanism within the rotor hub, substantially as described in Specification 1,043,108, so as to maintain the motor speed constant during normal running. The pitch control mechanism includes a rotor driven positive displacement rotary pump 50, Fig. 3 (not shown), supplying hydraulic fluid by way of a slidable spool valve 51 to chambers 64 or 69 on opposite sides of a piston 33 connected to crank-pins on the blades 13, so as to move the piston to the left or right and the blades into a coarser or finer pitch respectively in response to increases or decreases in rotor speed sensed by a flyweight governor 74. During normal governor controlled running a slidable sleeve 108 is urged against a flange 106 by a spring 109 and a further flange 110 on sleeve 108 acts as a coarse pitch adjustment stop for piston 33. When it is desired to retract the wind motor through an opening in the aircraft, a rod 93, Fig. 4 (not shown), within the leg (20) is moved upwardly so as to move a bell crank (89) about its pivot (90) and axially displace to the left rods (86), 87 into abutment with spool valve 51. The valve is thus moved to the left and control by the governor 70 over-ridden so that pressure fluid flows from the pump (50) via the valve into chamber 64 of the piston 33, forcing the piston to the left against stop 110 and the blades 13 into coarser pitch so as to slow the rotor down. Piston 33 continues to move to the left forcing stop 110 to be displaced against spring 109 and the blades to move into the reverse pitch range so that the rotor comes to a standstill and then rotates in the reverse direction. A hooked peg then engages in a slot at the end of the drive shaft (26) remote from the bevel gear (25) so as to lock the rotor in a position in which the wind motor presents its overall smallest cross-sectional area to the retraction opening in the aircraft. During the slowing down and locking of the rotor the pump (50) output pressure diminishes but the hydraulic pressure on piston 33 is maintained by a fluid accumulator comprising a piston (96) and a spring (98) adjacent the pump outlet. Upon engagement of the locking peg, a down-lock is automatically released and a jack operated to retract the motor, during which movement a cam at the upper end of the leg (20) displaces rods (93, 86), 87 so as to cancel the over-ride of the governor 70. Spool valve 51 thus moves to the right under the action of governor spring 74 placing chamber 64 of piston 33 in communication with drain and communicating the residual pressure in the chamber (99) of the hydraulic accumulator with chamber 69 of piston 33. This pressure and the action of spring 109 causes piston 33 to move to the right until sleeve 108 abuts fixed flange 106, which position corresponds to a relatively coarse pitch setting of the blades 13 suitable for starting of the wind motor when it is next ejected into the aircraft slipstream. In a modification, the hydraulic accumulator is replaced by a piston and cylinder device associated with sleeve 108 so as to displace the sleeve into reverse pitch position prior to wind motor retraction.