Patent GB-830997-A (GB)
Title: Pneumatic hydraulic power unit
IPC: B21J15/22
Filed: 1957-10-14
Abstract: 830,997. Engine valve-gears. CHICAGO PNEUMATIC TOOL CO. Oct. 14, 1957 [Dec. 12, 1956], No. 32050/57. Class 122(2). [Also in Groups XXII, XXVIII and XXIX] The press piston of a riveting or other tool 11 is supplied with liquid for a working stroke and is returned by compressed air, the pressure liquid being supplied by pneumatically-operated pumps 180, 218 and a regulator 23 being subject to the hydraulic pressure and serving, when a predetermined pressure is reached, to actuate an air distributer 21 to cut off the supply of compressed air to the pumps and to supply compressed air to the press piston for a return stroke. In the position shown, compressed air from a supply line 26 is applied via a line 35 to unseat a throttle valve 31 and thence passes through a line 39 to the return side of the press piston (not shown). A valve 32 is seated to block a passage 53, and air from the line 26 is supplied through a line 49 and round flats 54 on the valve 32 to a line 58 leading to a valve 59 of a manual control 22 on the tool handle. To initiate a working stroke control 22 is actuated to unseat valve 59 and thus vent line 58. Air from line 49 now unseats valve 32 and flows through passages 53, 143 to a chamber 146 to move a valve 34 to its uppermost position. Air is now supplied, through a line 127, and a groove 147, to a chamber 136 to seat valve 31 and thus vent line 39. Air is also supplied via groove 147 and a line 132 to lines 158, 185, 200. Line 158 feeds air into an hydraulic reservoir 14, forcing oil into chambers 154, 155 of the pumps 180, 218. Lines 185, 200 feed air via reversing valves 186, 186<1> to move pump pistons 187 against spring loading to force liquid from chambers 154, 155 through lines 167, 169 to a chamber 104 and thence through a line 156 to the working side of the press piston. At the ends of the stroke of the pump pistons valves 186, 186<1> are automatically operated to vent the compressed air chambers, whereupon the pump pistons are spring returned, the valves 186, 186<1> being operated at the end of the return stroke to initiate another pumping stroke. The pump pistons may be out of phase in order to give a constant output. When the pressure in chamber 104 has risen to a predetermined value, a piston 101 is moved against spring loading to unseat a valve 96 and thus vent a line 77. A valve 33 is thereby unseated, and pressure from line 53 is applied to an upper chamber of the valve 34 so that valve 34 is moved to its lowermost position by virtue of its spring loading. In this position line 132 leading to the pumps and reservoir is vented and air is supplied through line 39 to the return side of the working piston. The venting of line 132 allows a valve 176 to unseat, and oil behind the working piston returns to the reservoir through lines 169, 171, 174. When the pressure in the hydraulic lines has dropped sufficiently valve 96 seats, causing valve 33 to seat and valve 34 to move to its uppermost position to again pressurize the hydraulic system to operate the tool. Pumping action may be stopped at any stage by releasing control 22, thus seating the valve 59.