GB1260289A - Improvements in or relating to fluid pressure operated reciprocating motors - Google Patents

Abstract

1,260,289. Reciprocating motors. BUTTERWORTH HYDRAULIC DEVELOPMENTS Ltd. Jan.28, 1969 [Feb. 12, 1968], No.6797/68. Headings F1A and F1M. In a fluid operated reciprocating motor the stroke of the piston is controlled by closing the port through which the relevant motor chamber is exhausting by a land on the piston. The exhaust port for each motor chamber may be closable to control the stroke in each direction and one of a plurality of axially spaced ports for each motor chamber may be selected to be the exhaust port to be closed by the land or lands so that the stroke of the piston may be pre-selected. As shown supply and exhaust of pressure fluid to and from the motor chambers 5, 6 is controlled by a spool valve 11 exhaust from the motor passing to ports 40, 42 and then to exhaust passage 26. Shortly before the piston travel ceases in the direction X as a land 9 closes exhaust port 42 an auxilliary port 66 is opened by a land 64 to communicate pressure fluid acting through passage 73 with a chamber 16 to reverse the direction of spool valve 11. With chamber 5 open to pressure fluid, chamber 6 is opened to exhaust passage 48 via the respective port or ports 41, 41a or 41b which communicate with chamber 46 of port control device 47. The spool valve 11 and piston 1 are reciprocated in phase by the provision of a further chamber 76 in the port control device 47 communicating via passages 78, 79, 80 with ports 68, 68a and 68b controlled by a land 65 such that with the piston moving in the direction Y ports 41, 41a and 41b are closed before the respective port 68, 68a or 68b is opened. Pressure fluid is thus exhausted from chamber 16 through exhaust port 74 to reverse the spool valve 11. The valve as shown may be automatically reciprocated to give continuous reciprocation of the motor. To prevent shock at the end of each stroke restrictions 27, 28 open to exhaust to cushion the piston arrest.