GB1530591A - Combination of a door frame a door and a door latch - Google Patents

Abstract

1530591 Magnetic door latch TIMBER RESEARCH & DEVELOPMENT ASSOCIATION 12 Nov 1975 [12 Nov 1974] 48940/74 Heading E2A A door (11) is held in its correct closed position by a latch comprising a pair of magnets 14, 15, the magnet 14 being slidable vertically in a bore 16 in the top surface of the door (11) and the magnet 15 being fixed in a bore in a lintel of the door frame (12), (or vice versa) so that the magnets 14, 15 are in alignment when the door (11) is closed centrally in the frame (12) the magnet 14 sliding under the action of the magnetic attractive forces into engagement with magnet 15. The door (11) may be a door opening in one direction only but in the embodiments illustrated the door (11) is a swing door. In the embodiment of Figures 1, 2 the magnets 14, 15 are button magnets, with opposite poles on approximately semicylindrical sections on either side of a slot 17. The slidable magnet 14 is located in bore 16 on a central pin 21 (or alternatively on a pair of non-ferrous vertical pins in side slots in the magnet). If the door swings rapidly there will be insufficient time to lift the magnet 14, but if the door closes slowly like poles of the magnets will first repel each other, and then unlike poles will attract each other to provide a final closing force to the door. In opening the door, the magnetic attractive forces between unlike poles first resists such opening but once the door has started to open the repulsive forces between like poles assists such opening. In the arrangement of Figure 3 the magnet 14 slides in a cup 23 which is itself slidable vertically on the pin 21 in the bore 16, a compression spring 24 urging the magnet against stops (not shown). On either side of the magnet 15 in the lintel is a button 25 which cooperate with bevelled edges 26 of the magnet 14 as the door is closed; the buttons 25 also prevent the door being opened unless a substantial thrust is applied thereto. The buttons (25) can have a steeper curved head away from the magnet (15) (see Figure 4, not shown) or vice versa. Where buttons (25) are used, conventional flat magnets can replace the button magnets. As an alternative to the button a bent leaf spring (28) is pinned to the frame (see Figure 5, not shown).