| 摘要 |
490,666. Filters. ZWICKY, J. Dec. 18, 1936, No. 34862. [Class 46] A filter element 4 such as described in Specification 487,164 comprising gauze enclosed between two closely fitting perforated cylinders is cleansed, as the element rotates, by a reverse flow of liquid into an elongated nozzle 6, which is pressed by a spring 9 against a generator of the element. The casing has an inlet 1 and filtrate outlet 3. The nozzle 6 normally engages an imperforate strip of the element. The outlet from the nozzle is controlled by a valve 12 which is opened by a tappet 16 when the filter element is rotated by means of a handle 5 and a roller 15 engaging a cam 14 on the element is brought into contact with the tappet. A perforated pipe 23 for the supply of steam to aid in cleansing may extend within the element. A diaphragm 18 subject to the pressures within and without the element operates a visual or audible signal, e.g. a spring- wound bell 22, when the element requires cleaning. Alternatively, the diaphragm 18 may control a motor which rotates the filter. As shown in Fig. 4 the diaphragm is replaced by a piston 28 which operates a switch 27 controlling a motor 26 which rotates the filter element through a friction clutch. After a single revolution the switch is opened by an arm 31 engaging a notch in a cam surface 33, unless the pressure difference on the two sides of the piston is still sufficient to hold the piston in its outer position. |
