Patent GB-891662-A (GB)
Title: Hydraulic control system for a fluid motor
IPC: B30B15/16
Filed: 1959-10-16
Abstract: 891,662. Hydraulic apparatus. MERCIER, J. Oct. 16, 1959, No. 35185/59. Class 69 (2). An hydraulic system for operating a fluid motor 30, Fig. 1, such as the motor of a press 33, comprises a high pressure source of fluid 11  and a pressure reservoir 21 providing a lower pressure source of fluid, both sources being connected to the motor by valve means 15 having at least three operative positions, the first position connecting the pressure reservoir to the motor to effect actuation thereof in one direction, the second position connecting the high pressure source of fluid to the motor to effect further actuation thereof in the same direction, and the third position connecting the high pressure source of fluid to the motor to effect actuation thereof in the opposite direction, the high pressure acting through the motor to recharge the pressure reservoir. In the first position of the valve, the pressure reservoir 21 drives the motor 30 which is connected to a pinion engaging a rack on the movable part 31 of the press. At the end of the stroke, the valve is moved to its second position to connect the high pressure source, which may be a compressor, to the motor to apply the working pressure. In the third position of the valve, the high pressure drives the motor in the opposite direction to lift the part 31, the other side of the motor being connected to the pressure reservoir which is thus charged to a valve determined by a pressure relief valve 23. In another embodiment, the high pressure source is an accumulator 41, Fig. 2, which is charged by a pump 35 when the spool 45 of the valve is in its neutral position, as shown. The accumulator, the pressure reservoir 71, the motor 60 and a reservoir 37 are connected to the valve, the spool of which can be moved to three positions by a lever 49. In the first position, the spool of the valve is moved to the right and the reservoir 37 is connected by lines 76 and 55 to the lower chamber A of the motor, the upper chamber B of which is connected to the pressure reservoir 71 so that the piston 61 of the motor moves downwardly. Further movement of the valve to the right connects the accumulator 41 to the chamber B to apply the high pressure to the motor. When the valve is moved to the left, past the neutral position, the accumulator is connected to the chamber A to move the piston upwardly, the upper chamber B of the motor being connected to the reservoir so that the high pressure therein charges the pressure reservoir 71 to a value determined by a relief valve 74. In a further embodiment, the motor comprises two cylinders having interconnected pistons, one end of each cylinder being connected to the valve controlling the connections to the high pressure source, pressure reservoir and reservoir. In a still further embodiment, the valve means comprises three valves 117, 118 and 136, Fig. 4, the spools of the valves 118, 136 being connected by a rod 153, 154 to one end of a lever 156 pivoted at 165 to a control rod 164. The spool of the other valve 117 is also connected by a rod 157 to the lever 156 which has one end urged to a central position by springs 162, 163. Limited upward movement of the rod 164 moves the spools of the valves 118, 136 upwards to connect the low pressure reservoir 146 by lines 145, 133 and a one-way valve 143 to the chamber B of the motor to move the piston 127 upwardly. Further upward movement of the rod moves the spool of valve 117 upwardly to connect the high pressure accumulator 115 to the chamber B through lines 114 and 132. When the rod 164 is moved downwardly past its neutral position, the spools of valves 118, 136 first move downwardly to connect the accumulator through line 124 to the chamber A, the chamber B being connected by lines 132, 145 and a one-way valve 144 to the pressure reservoir 146 which is thus charged to a value determined by the setting of a valve 150. Further downward movement of the rod 164 moves the spool of valve 117 so that the chamber B is connected by a line 138 to the reservoir 113, the whole of the pressure in the accumulator then serving to move the piston downwardly.