| 摘要 |
924,505. Mineral-mining machines. EICKHOFF MASCHINENFABRIK U. EISENGIESSEREI m.b.H. GEB. Dec. 16, 1959 [Dec. 24, 1958], No. 42707/59. Class 68 (1). [Also in Group XXIX] Apparatus for controlling a fluid-operated motor, such as a motor 7 arranged to drive the haulage device of a coal-getting machine, comprises a valve 10 adapted to open when the pressure in a pipe 4 between a source 1 of fluid pressure and the motor rises to a predetermined value and to remain open when the pressure has fallen below the predetermined value. The source of fluid pressure may be a vane-type pump 1 having the eccentricity of its rotor 2 controlled by a cam 3 to vary the output of the pump which is connected to the pipe 4 leading to a valve 6 controlling the flow of fluid to the motor 7, which may drive the winch of the machine, or a motor 8, which may move a swinging jib or other device. The pipe 4 is provided with a one-way valve 5 and is connected by a pipe 9 to the valve 10 which has a stepped piston 11 urged by a spring 12 to a position closing an exhaust passage 13. The pressure in the pipes 4 and 9 acts on the smaller portion of the piston and when the pressure rises to a predetermined value moves the piston against the spring 12 to the right. The pressure can then act on the larger portion to move the piston rapidly and open the passage 13, the pressure acting on the larger portion maintaining the valve open at pressures below the predetermined value. The one-way valve 5 prevents a rapid fall of the pressure in the motors which may operate slowly until the pressure therein is reduced by leakage. The passage 13 can only be closed by adjusting the cam 3 of the pump to reduce the output pressure to a value which will permit the spring 12 to return the piston 11 to its original position. The arrangement prevents excessive pressure in the system and consequential raising of the temperature of the fluid. An arrangement is referred to in which a pressure-relief valve is provided in the fluid circuit and allows the pressure in the circuit to act on a piston connected to the rotor or stator of the pump. |
