Patent GB-282972-A (GB)
Title: Weighing devices
IPC: G01G13/02
Filed: 1926-12-20
Abstract: 282,972. Rees, W. H. Dec. 20, 1926. Automatic-feed weighers.-In an automaticfeed weigher in which a member is movable according to the load in the hopper, a spark is adapted to pass between the movable member and a second member in circuit therewith, whereby the conditions of current flow in a second or control circuit are altered and the feed gate is allowed to close. The invention, as showm, is applied to a machine comprising a rotary, compartmented receptacle 6 suspended from the platform 2 of an automatic weighing-scale 3 having a pointer 72 registering with a dial 73. A feed gate 29, pivoted at the mouth of a supply hopper 28, is automatically opened during rotation of the receptacle by the engagement of one of a series of cams 53 disposed around the circumference of the receptacle with a roller 54 on the gate, and is held in open position by a spring-pressed latch 38 engaging a lever 37, Fig. 5. The lever 37 is pivoted near the. pivot of a second lever 36 the outer end of which is normally engaged by the armature 33 of an electromagnet 81, the arrangement being such that when the magnet is energized the feed gate is allowed to close. A member 52 attached to the lever 36 closes a switch 51 while the gate is open. Rotation of the receptacle is controlled by a brake disc 18 axially movable on a shaft 13 that is connected by gears 12, shaft 11 and pinion 9., to a ring gear 8 surrounding the receptacle. Excessive speeds of rotation of the receptacle are prevented by the centrifugal action of balls 16, which presses the disc 18 into engagement with a rotationally fixed disc 21. Upon the opening of the feed gate, a switch 64, in a circuit 66 containing electromagents 26, is opened, thereby allowing the disc 21 to be pressed downwardly against the disc 18 by a spring 22, and bringing the receptacle to rest. A current normally flows from a source of supply in a circuit comprising lines 46, 48, primary coil 49, electromagnet 47, switch 51, and line 42 back to the supply. This current induces a voltage in a secondary coil 85 but is too small to attract the armature 43 of the magnet 47. One end of the secondary 85 is connected to earth and the other end to an electrode 87 adjustably mounted on the dial 73. The pointer is also connected to earth so that a difference of potential normally exists between the pointer and the electrode. When the predetermined weight of material has passed into the receptacle, the pointer is in a position adjacent the electrode, and a spark passes, thus causing a surge of current in the primary that is sufficient to cause the attraction of the armature 47. A circuit is thereby established through the magnet 31, the feed gate is closed, and the switch 51 opened. A lever 56 descends, after the closing of the gate, to close the switch 64, the speed of descent being retarded by a dashpot to allow the material in suspension at cut-off to influence the weighing-apparatus. Upon the closing of the switch 64, the circuit 66 is closed, thereby raising the disc 21 and allowing the receptacle to rotate. Included in the circuit 66 is a magnet 67 that operates a clutch 77 to couple the spindle 71 of the pointer to a spindle 68 during the backward rotation of the pointer as the receptacle discharges. The spindle 68 is connected to a revolution counter 81, and to a pointer 82 registering with a dial 83 similar to the dial 73. The total weight of material that has passed through the machine is given by the dial capacity multiplied by the counter indication, plus the dial indication. The dash-pot comprises a piston 58 movable in a cylinder 57 connected to an oil reservoir 59 by a passage controlled by a valve 61. The bore of the cylinder is widened at the bottom to allow the piston to move rapidly during the last part of its downward stroke and thereby prevent sparking at the switch 64.