Patent GB-797223-A (GB)
Title: Improvements in or relating to magnetically-operated control or signalling apparatus of the control magnet and receiver type
Inventor: BAUMGART SIEGFRIED
IPC: B66B1/50
Filed: 1955-10-07
Abstract: 797,223. Winch end stop gear; mine cage apparatus; interacting track and vehicle apparatus. SIEMENS & HALSKE AKT.-GES. Oct. 7, 1955, No. 28701/55. Classes 78 (5) and 105. [Also in Groups XXXV and XXXVII] In a magnetically-operated control or signalling apparatus such as may be used for controlling lift cages in mines and hoists to trigger a switching operation, e.g. when the cage approaches the pit mouth, and consisting of a relatively movable control magnet and receiver, the control magnet 31 is of the bar type with its magnetic axis transverse to the path of movement so as to influence the receiver as they pass each other, and the receiver has two polepieces 17, 18 separated by an air gap 19 and located one behind the other in the path direction so that one pole of the control magnet 31 will be directed towards each polepiece 17, 18 in turn as the control magnet passes the polepieces to change the direction of the flux in the gap 19 causing a polarized armature 20 arranged in the gap with its flux also effective in the polepieces 17, 18 to change its position accordingly to initiate control or signalling operations. As shown, the magnet 31 mounted on an iron plate 30 is movable, being, for example, mounted on a pit cage, past a fixed receiver, the armature 20 of which, pivoted at 7, is polarized by a magnet 9 having a portion bent towards the armature 20, this latter having flux-guiding projections 10. As the control magnet 31 passes the receiver, the flux in the gap 19 varies, as shown in curve 25, and always passes through zero at the point 26, i.e. when the control magnet is in the position of symmetry with respect to the polepieces 17, 18 regardless of the distance between the line of travel of the control magnet and the said polepieces. To ensure that the armature 20 changes its position as the control flux passes through zero, the contact 21 is so adjusted that when it engages the adjacent end of the armature 20, the other end of armature 20 is midway between the polepieces 17, 18 and the polarizing flux passing through the armature is equally divided between the polepieces and the armature is in a state of unstable equilibrium. Normally armature 20 bears against contact 22, since its other position is unstable, and as the magnet 31 approaches in the direction denoted by arrow C the attraction between armature 20 and polepiece 17 increases and that between armature 20 and polepiece 18 decreases until with the flux value represented by point 28 on the curve 25, the armature moves over against the contact 21 and remains so until the flux falls to zero and the armature returns into the stable position engaging the contact 22. This movement may be employed to stop the upward pit-cage drive and render the brake operative. To this end a condenser 23 is charged when the armature 20 touches the contact 21 and discharges through a relay coil 24 when the armature touches contact 22, the relay 24 being arranged to initiate the control operation. A spring may act on the armature but must be so adjusted that its directional force is zero when the armature occupies a central position between the polepieces 17, 18. The invention is also applicable to stopping vehicles or conveying means in a predetermined position or to determine the position and direction of travel thereof.