GB914660A - Automatic door closer - Google Patents

Abstract

914,660. Door closers. MANKEL, R. Feb. 2, 1961 [March 10, 1960], No. 4039/61. Class 65 (1). A door closer comprises a casing 10 containing a coil tension spring 27 and a pivotally-mounted hydraulic piston and cylinder brake 31, 32, the closing shaft 14 which is rotatably mounted in the casing having a crank 19 connected by a linkage system 20, 22 to a rocking lever 24 engaged by both the spring and the brake. In the region of the crank 19 the closing shaft 14 is reduced in diameter so that only a portion 42 remains, and the link 22, which is pivoted to the link 20 at 21, comprises two parallel webs each having a bent lug 26 adapted to engage the link 20 to act as a stop. When the door (not shown) is closed the links are approximately aligned (Fig. 5) and they remain so until the door has opened about 60 degrees when the link 20 abuts a surface of the shaft portion 42 (Fig. 6), subsequent opening of the door then causing the linkage to bend about its pivot 21 until the 180 degrees open position is reached (Fig. 8) when the link 22 also abuts the shaft portion 42 and arrests the opening movement. In this position the pin 23 by which the spring 27 is connected to the rocking lever 24 is so disposed relative to the linkage 20, 22 and the closing shaft that the closing torque is reduced to zero. When the door is released from this position it begins to close under the action of the spring 27 and during the closing movement the link 22 rotates in an anti-clockwise direction relative to its pivotal connection 23 with the rocking lever 24. As soon as the 60 degrees position is reached (Fig. 6) the link 20 commences to rotate in a clockwise direction relative to the crank 19, and the friction at the pivots 19, 23 is arranged to be sufficient to cause the linkage, in spite of the tension caused by the spring 27, to pass slightly over-centre until the stops 26 on the link 22 abut the link 20. By this means the linkage forms a rigid strut so that if the door should be forced manually towards the closed position after the brake has come into action there is little risk of the linkage collapsing. An abutment surface 45 is formed on the casing to limit such collapse if, through unfavourable circumstances, it should occur. A bore 39 is formed in the wall of the brake cylinder 32 so that braking action occurs only shortly before the piston 31 has finished its inward stroke, the braking action being adjustable by means of a valve 35 which may contain a heat-sensitive insert to adapt the area of the valve passage to the temperature-responsive viscosity of the hydraulic fluid. A pressure relief valve 34 with an adjustable spring and a non-return valve 38 are also provided. A spring-loaded pin 41 (Fig. 3, not shown), projecting from the top of the casing near the shaft 14 may be provided to engage a recess in the lever arm carried by the extension 15 of the shaft to hold the door in a predetermined open position. Alternatively (Fig. 4, not shown), notches may be formed on the edge of the link 20 which cooperate with a spring-loaded pin inside the casing. Specification 778,850 is referred to.