GB1121956A - A synchronized hydraulic system - Google Patents

Abstract

1,121,956. Hydraulic actuators. DAIKIN KOGYO CO. Ltd. Aug. 16, 1966 [July 27, 1966], No. 36661/66. Heading F1P. Hydraulic actuator pistons 4, 4<SP>1</SP>, Fig. 5, are urged outwardly of cylinders 3, 3<SP>1</SP> at a predetermined speed ratio, e.g. 4 to 1, by fluid forced along lines III, IV from cylinder spaces b, a, by pistons 10, 10<SP>1</SP> connected together by a rod 11 and of area ratio equal to said speed ratio, the pistons 10, 10<SP>1</SP> being themselves displaced by fluid forced by a pump 1 through a selector valve 2 when in position A, a line 1 and inlet ports 12, 12<SP>1</SP> of cylinder spaces a, c. Fluid exhausted from the upper ends of cylinders 3, 3<SP>1</SP> is returned through a line II and valve 2 to a tank T and near the ends of the outward stroke of pistons 4, 4<SP>1</SP> any lack of synchronization is rectified by passage of pump fluid through a port 31 of cylinder space c, a check valve member 27, Fig. 6, when unseated by an arm 23 of rod 11 near the end of its stroke, non-return valves 29, 29<SP>1</SP> and lines III, IV. To return pistons 4, 4<SP>1</SP> valve 2 is moved to position B to admit pump delivery to the outer ends of cylinders 3, 3<SP>1</SP> whilst the inner spaces e, f exhaust through lines III, IV into cylinder spaces b, a thereby displacing pistons 10, 10<SP>1</SP> to the other end position and as they approach this position a rod arm 23 opens a check valve 27 thereby connecting cylinder spaces e, f through non-return valves 30, 30<SP>1</SP>, valve 27, cylinder space C and line I to tank T. In a modification pairs of check valves 14, 14<SP>1</SP>, 15 15<SP>1</SP>, Fig. 2, are located within bores D of connected pistons 10, 10<SP>1</SP> which as shown are of equal diameter corresponding to a speed ratio of unity for the actuator pistons. Near the end of the outward stroke of the actuator pistons and hence of pistons 10, 10<SP>1</SP> valve stems 16, 17 abut cylinder faces 20, 20<SP>1</SP> and pump pressure is admitted through said check valves to cylinder spaces b, d, ports 13, 13<SP>1</SP> and lines III, IV to actuator cylinder spaces e, f to correct errors of synchronization of pistons 4, 4<SP>1</SP>.