Patent GB-894115-A (GB)
Title: Improvements in the automatic control of automatic weighing and feeding machines
Inventor: LLOYD ARTHUR KENNETH
IPC: G01G13/24
Filed: 1959-10-14
Abstract: 894,115. Weighing apparatus. IMPERIAL CHEMICAL INDUSTRIES Ltd. Sept. 30 1960 [Oct. 14, 1959], No. 34780/59. Class 143. Automatic feed controlling apparatus for use with weighing equipment, which comprises a chamber restrictively connectable to a source of constant air pressure, the chamber having at least one small opening from which the air emerges and being attachable to a weighing machine such that air issuing from the opening impinges on, at least during part of the movement thereof, a weight-measuring element of the weighing machine movable relative to the opening over a predetermined range of weights upon the weighing machine, increasing reduction of the free space near the opening by the element causing increasing back pressure in the chamber which is adapted to control the operation of an automatic feeding device such that between predetermined lower and upper limits of the increasing back pressure the rate of feed of material from the device is continuously reduced as the back pressure increases until at the predetermined upper limit the feed is caused to stop. Two feeler gauges 10 extend from the beam 1 of a weighing machine each into a slot 11 between nozzles 13 and 14 supplied with air at 30 lbs. / sq. inch through restrictors Rc, RF to provide minimum back pressures of 4 and 4.5 lbs. /sq. inch at chambers 8 and 9 respectively. During the weighing the movement of the feeler gauge in chamber 8 sets up a back pressure which passes to a pneumatic relay C supplied with air at pressure of 25 lbs. / sq. inch and transmits the pressure to relay A which passes the pressure to a valve V1 which deenergizes then to relay B supplied with air at pressure of 80 lbs. /sq. inch which increases the air pressure in the chamber 7 of a section 6 controlling the supply of material from the hopper 5. Each relay comprises a vessel divided into two by a flexible diaphragm, on one side of which is the controlling back pressure and on the other side a greater pressure controlled by a ball valve operated by the diaphragm. An escape nozzle provides an exit for excess air and the side having greater pressure also has an exit line to allow air to pass in large quantities at a controlling pressure. At a pressure of 4.5 lbs./sq. inch the chamber 9 commences to transmit a back pressure- and at a pressure of 13.5 lbs./sq. inch the supply of material is cut off by the section 6. The chamber 7 receives an air pressure of 25 lbs./sq. inch from relay B, transmitted from the relay D and energized valve V2. The valve V2 causes the air pressure to pass to the valve VI and a pressure of 25 lbs./sq. inch from the valve V4 holds the valve V1 and retains the section 6 closed until operation recommences by pressing the push button of the valve V4 which de-energizes valves V3, V1 and V2. Releasing the press button energizes the valve V3 and automatic filling commences. The weighing beam may rest on stops until within a small weight of the predetermined weight. The air from the nozzles 13 and 14 may impinge directly on the weighing beam. The back pressure may control an electric circuit which controls the supply such as a vibrating feeder the amplitude of which reduces. Two valves providing fast and dribble feeds may simultaneously supply material from the hopper and the relays A and C have independent circuits each incorporating a valve and close the valves in succession. The valve controlling the supply of material comprises a flexible tube through which the material flows. A rigid casing enclosing the tube is provided with one or more openings for air under pressure to admit air to close the valve or to release air to open the valve. Specification 825,810 is referred to.