Patent GB-190417059-A (GB)
Title: Improvements in Electro-magnetic Controlling Devices, especially applicable for Use in Automatic Weighing Apparatus.
Inventor: DARRAH HENRY MOSTYN
Filed: 1904-08-04
Granted: 1905-08-04
Abstract: 17,059. Darrah, H. M., and Hackett, L. A. Aug. 4. Electric weighing- apparatus.-A controlling-device for an electrically-controlled automatic weighing-apparatus comprises an arrangement o f circuits and contacts such that a scale beam acting upon one contact causes the full current to energize primary valveactuating magnets to open a valve, and acting upon other contacts introduces secondary magnets which hold up these contacts, and so reduce the main current that the valve is closed again. The application of the invention to a valve opened electrically is shown in Figs. 1 and 2. Upon the valve 1 are mounted the horse-shoe valve magnets 7, the armature 9 of which is attached to the stem 8 of the valve, its movement being guided by rods 10. Fixed to one of the rods 4 which support the crosshead 5 carrying the main terminals 11 and the lamp or other resistance 13 is the lever 14 carrying the clamp 21 and the carbon contact 22, which engages, when the armature is at its lowest position, with a similar contact 20 depending from the crosshead 5. When the armature is attracted, the rod 16 strikes the lever 14 and separates the contacts 20, 22. The current from the main enters by the terminals 11, one of which is connected to the magnet windings 7 and the other to the lever 14 and contact 22 and also to the contact 20 by way of the lamp 13, the bracket of the contact 20 being also connected to the magnet windings. When the lever 14 is down, the current passes through the magnet windings, and returns through the lever. When the lever is raised, the circuit through the lamp only is closed, so that the armature is feebly held by the magnet. The spring contacts 26, 27 are arranged above and below the scale beam 25, the contact 26 resting normally against the fixed contact 32, and the elastic contact 27 resting normally clear of the fixed contact 33. When the scale beam depresses the lower contact, the magnets 7 are energized with the full current, and the valve 1 is opened by the attraction of the armature. The beam 25 rises, when it becomes balanced, breaking the circuit between the contacts 26, 32, and the magnets 34 are energized to attract and hold up the contact 26. The resistance of the magnet coil 34 lowers the current through the magnets 7, so that the armature 9 falls and the valve is closed by a spring or by gravity. On the object weighed being removed, the scale beam again falls on the lower contact 27, and the valve is reopened. The valve may be closed by simply breaking the circuit, for which purpose the arrangement shown in Figs. 7 and 8 may be used. A cup 35 contains mercury into which dips the platinum-tipped end of a lever 36 screw-threaded at its fulcrum for adjustment. The scale beam lies below an adjustable ebonite sleeve 37 on the lever and, when at its lowest point, the scale beam allows the point to dip into the mercury. The application to a valve operated mechanically is shown in Figs. 3, 4, and 5, in which the valve is opened through the rod 40 by the hand or foot operated lever 41, which is notched at 42 and slides in the frame 43. The spring-pressed latch 44, connected with the armature 47, normally enters the notch 42 and locks the lever 40 in its highest position. When the armature is attracted, the lever is unlocked and allowed to fall, and closes the valve. In this case the secondary magnets 34 are connected in series with the magnets 7. Instead of the terminal 33 below the scale beam, a spring terminal 33, Fig. 4, alongside the lever 40 may be used. The apparatus is suitable for weighing or measuring liquids and other substances in small tins.