GB545916A - Improvements in and relating to fluid-operated motors for windscreen wipers - Google Patents

Abstract

545,916. Windscreen wipers ; liquid-pressure engines. ACROTORQUE CO. Dec. 17, 1940, Nos. 17780 and 17781. Convention dates, May 22 and Oct. 5. [Class 69 (ii)] [Also in Group XXIII] A windscreen-wiper motor of the kind in which a double-ended piston slides in a cylinder closed at both ends and supplied with fluid by poppetvalves actuated by the piston is constructed with spring toggle devices for operating the piston. As applied to the oscillation of windscreen wipers for aircraft by means of oil under pressure which is supplied by the fluid system for operating the undercarriages, the input pipe for the oil leads by passages 14, 16, 18 to valve chambers 20 from which the oil is' directed by valves 26 alternatively to either end of a cylinder 60 in which moves a piston rod fitted at each end with a piston 52. With each valve 26 is associated a valve 42 which when open connects one end of the cylinder to exhaust. There are two pairs of valves 26, 42 and the valves 42 are operated by the motion of the piston rod, and the arrangement is such that as each valve 42 is opened the corresponding valve 26 closes under spring action. As shown the piston has completed its movement to the left and the left-hand valve 42 is closed and the left-hand valve 26 open to connect the pressure fluid to the left-hand end of the cylinder so as to start the movement of the pistons to the right. The shaft 58 of the windscreen wiper is oscillated by a rack 54 on the piston rod and a pinion 56, and eccentrics 66 operate the valves 42 by means of lever arm 74 which is rotated by a spring-controlled toggle mechanism comprising a link 68, lever 70 and spring 78 so as to give a snap-over movement to the valves 42 opening and closing the other. The exhaust from the cylinder leads to a sump 64, and the cylinder is fitted with a liner 60 formed with grooves 62 at its extremities which connect via passages 36, 46 to the valve. In a modification, Fig. 5, the toggle mechanism is actuated directly by the piston rod, and controls a cam 88 which acts upon thimbles 82 upon which act springs 80 which with the cam 88 in the piston shown act upon the righthand valve 42 with a greater pressure than a spring 50 acts upon the corresponding valve 26 so that the right-hand end of the cylinder is connected to exhaust through a hole 84 and other passages as in the first modification. The lefthand valve 26 is, however, open and the corresponding valve closed, and the hole 84 is closed by the thimble. A single motor may operate four wipers arranged in conjunction with an aircraft cockpit having a four-panel windscreen. The Specification as open to inspection under Sect. 91 also describes a windscreen wiper now forming the subject-matter of Specification 545,989, [Group XXIII]. This subject-matter does not appear in the Specification as accepted.