Patent GB-682769-A (GB)
Title: Balancing apparatus, particularly for hydro-extractors
IPC: F16F15/36
Filed: 1949-04-14
Abstract: 682,769. Centrifugal-machines. KAHN, L. M. April 14, 1949 [May 26, 1948], No. 10164/49. Class 23 [Also in Groups XIX and XXXV] A rotary hollow member, such as a hydro-extractor, is provided with a pocket connected with a feed ring rotating with the member, the arrangement permitting liquid to be supplied to the pocket to correct the balance of the member. The perforated basket 17 of a washing or cleaning machine is rotated at high speed for drying and is provided with pockets 21, 22, 23 having feed rings 35, 37, 38 respectively. The liquid, which is preferably the cleaning liquid, is supplied from a tank 51, by a pump 53, and a pipe 55 having a master valve 54 and branch pipes 29, 30, 31. The branch pipes are fitted with jets 32, 33, 34 directing liquid to the respective feed rings, the flow of liquid in each of the branches being controlled by solenoid operated valves 26, 27, 28. Centrifugal force urges liquid from the feed rings to the pockets, ana holds the liquid in the pockets. As the basket slows down the liquid is discharged from the pockets by openings such as 46. The discharged liquid drains into a tank 50, is filtered, and led to the tank 51 by a pipe 52. A crystal, micro-switch or other vibration pick-up 75, in contact with the casing of the machine, detects the magnitude of out of balance and a commutator 98 housed in a casing 99 mounted at the end of the drive shaft 19 locates the position of out of balance. Signals from the -crystal and commutator are applied to an electrical circuit which causes the solenoid operated valves to inject liquid into a pocket or pockets opposite the site of out of balance, and prevents full speed rotation of the basket until balance is obtained. Voltages generated by the crystal are amplified by a thermionic valve 78 and fed to the grids of thermionic valves 92, 93, 94, the plate voltages of which are successively supplied by the commutator. When the grid voltage of any of the valves 92, 93, 94 exceeds the firing voltage whilst the plate voltage is applied, current will flow through one of the relays 135 to close contacts with the result one of the solenoid operated valves is opened to supply liquid to a pocket, one of the warning lamps 148, 150, 151 lights, and a circuit AB is closed. The setting of a potentiometer 115 determines the magnitude' of vibration at which the valves 92, 93, 94 function. To prevent intermittent flow of liquid to the pockets during balancing, condensers 155, 156, 157 in the relay circuits provide a time lag or dash pots are provided in the solenoids of the valves 26, 27, 28. Condensers 121 prevent transient disturbances of the basket or casing causing flow of liquid to the pockets. The circuit AB is connected to terminals in a circuit, Fig. 5 (not shown), which opens the master valve when one or more of the valves 26, 27, 28 are opened and in which a relay having a time delay is incorporated to shut off the drive motor 18 after one or more of the pockets have been filling for a given time. Thermionic valves 87, 88 fed by the valve 78 function to open a circuit CD, connected to the drive motor circuit, to shut off the motor when the out of balance is excessive. In a modification of the circuit shown in Fig. 4, a single thermionic valve may replace the valve 92, 93, 94. The circuit shown in Fig. 4, may be replaced by a circuit, Fig. 14, (not shown), comprising a micro-switch, solenoids and condensers. In a modified mounting for the crystal, Fig. 10, 11 (not shown), an arm mounted on the inner support for the drive shaft engages a crystal mounted on the outer support. In a further modification of the crystal mounting, Figs. 12, 13 (not shown), a rubber pad is inserted between the end of the basket and the end of the drive shaft which is hollow, and a rod fixed to the end of the basket engages the crystal fixed to the outer support for the drive shaft. The machine may rotate on a vertical shaft and the pockets may be external to the basket. In a modified form of the machine, Figs. 7, 8 (not shown), a horizontal perforated cylinder is provided at each end with a bearing, a a crystal, feed rings and pockets. Specification 663,829 is referred to.