GB862348A - Fluid-operated reciprocating devices - Google Patents

Abstract

862,348. Fluid-pressure engines. KEELAVITE CO. Ltd. Dec. 18, 1959 [Dec. 19, 1958], No. 41187/58. Class 69 (2). [Also in Group XXVI] A fluid-operated reciprocating device comprises a piston 3, Fig. 1, which is reciprocable relative to a cylinder 1 and has parts 19, 20 co-operable with parts 5, 13 of a control valve at the ends of the cylinder to restrict or prevent flow from the end of the cylinder to which the piston is moving, the resulting increase in pressure between the adjacent faces of the piston and associated valve part moving the latter to control one or more inlet and/or outlet ports to reverse the direction of movement of the piston. Fluid from an inlet 18 is permanently supplied to the right-hand end of the cylinder to urge the piston 3 to the left and, because of differential areas on the valve part 13, urge that part to its left-hand position, as shown, whereby a chamber 10 is connected to a relief 18a ; the space to the left of the piston is also connected to the relief by ports 6a in the valve part 5. Towards the end of the stroke to the left, the part 19 of the piston enters a bore 6 in the valve part 5 and restricts the flow of fluid from the cylinder to increase the pressure in the cylinder and move the part 5 to the left so that the inlet 18 is connected by the passages 6a to the left-hand face of the piston, the pressure acting on the larger area of that face moving the piston to the right. Towards the end of the stroke to the right, the part 20 of the piston enters the bore of the valve part 13 to restrict the flow from the right-hand end of the cylinder and the increase in pressure moves the part 13 to the right to connect the chamber 10 to the supply 18. The valve part 5 then moves to its initial position to re-connect the left-hand end of the cylinder to the relief 18a ; the piston thus moves to the left as also does the valve part 13. The parts of the valve may be moved by mechanical engagement by the piston during the initial starting movements. In another embodiment, the two parts 22b, 22c, Fig. 2, of the valve are connected by a sleeve 22 which is disposed within the cylinder and within which the piston reciprocates. Fluid from a supply 30 is permanently connected to the right-hand face of the piston and the left-hand face of the piston is connected to the supply 30 and relief 29 alternately by the movements of the sleeve at the ends of the strokes of the pistons. Ports in the part 23a of the piston and in the right-hand end of the sleeve damp the movements of the piston during reversal. In a further embodiment, the positions of the sleeve are determined by a mechanical stop. The cylinder may be the moving member and the piston stationary.