SPECIFICATION Door closers This invention relates to door closers.
Such closers are known in which the major part ofthe closer can be mounted within a cavity in thedoor. The known closers comprise a cylinder whichfits within the door cavity and which has therein acoil compression spring biasing a pulling member, the pulling member being attached to a chain whichextends from the cylinder and is attached to the door jamb. When the door is opened the spring is compressed and when the door is released the compression force acts to urge the door towards the jamb,i.e. in a sense to close the door.
The present invention is particularly concerned with a door closer having a cylinder for insertion in a door cavity, the closer including damping means for damping the closing movement of the door.
In accordance with the invention, there is provided a door closer comprising a cylinder for insertion in a door cavity in an edge of the door adjacent the door jamb, an expansible, sealed chamber within the cylinder in which a damping piston works, a piston rod connected to the piston and extending outwardly from the chamber towards one end of the cylinder which when the cylinder is mounted in the door is adjacent the jamb, resilient means biasing the piston towards the other end of the cylinder, and connecting means for connecting the piston rod to the doorjamb.
The arrangement is such that when the door is opened, energy is stored in the resilient means, but when the door is released the stored energy urges the door to its closed position, at least part of the closing movement being damped by the piston.
Preferably, one end of the chamber comprises a movable seal which permits expansion of fluid in the chamber, due to temperature changes or movement of the piston rod. The piston rod preferably passes through the seal and the movable seal is preferably resiliently biased towards the closed end of the cylinder and movable against the bias to permit expansion of the chamber.
The inner end of the chamber preferably has an enlarged cross section in which the piston does not have a damping effect. Thus, at the end of the door closing movement the door can latch without damping resistance.
A door closer in accordance with the invention will now be described, by way of example, with reference to the accompanying drawing which shows an axial cross section of the closer.
The closer comprises a cylinder 1 adapted for insertion in a door cavity such that the right hand, open end 2, hereinafter referred to as the outer end, opens at the edge of the door adjacent the jamb. The cylinder 1 has a chamber 3 between the inner closed end 4 and a movable seal 5, the chamber being filled with damping liquid. A damping piston 6 works within the chamber 3 and may be of any suitable form, for example as illustrated and described in theProvisional Specification of our Patent ApplicationNo. 2463/78. The piston 6 is biased towards the innerend of the cylinder 1 by a coil compression spring 7 which seats at its outer end against a collar 8, the collar being fixed to the cylinder 1.
A piston rod 9 is attached to the piston 6 and passes outwardly through the collar 8 and sealingly through the movable seal 5. At its outer end the piston rod 9 is attached to a slider 11 which acts as a seatfora coil compression spring 12 that biases the movable seal 5 inwardly and the slider 11 is connected to one end of a pivotable connector 13, the other end of which is secured to the door jamb.
When the door is fully opened, the piston and cylinder adopt the illustrated positions with the spring 7 compressed and the slider 11 near the outer end of the cylinder. If the door is released, the spring 7 urges the piston towards the inner end of the cylinder and thereby acts to urge the door to its closed position. Closing movement of the door is damped by the piston 6. As the piston 6 approaches the inner end of the cylinder, at which there is a portion 14 of enlarged cross section, the piston seal 15 comes out of contact with the cylinder 1 and thereby becomes ineffective. Thus the movement at the end of the travel of the piston is not damped and the door is permitted to latch without damping resistance.
It will be seen that changes in volume of the fluid in the chamber, caused either by heat or by movement of the piston rod 9, are accommodated by the moveable seal 5. Thus, in the event of a fire, which causes expansion of the fluid in the chamber, the seal 5 moves to accommodate such expansion and there is no hydraulic locking effect to prevent the door opening, as might occur if the seal 5 was fixed relative to the cylinder.
1. A door closer comprising a cylinder for insertion in a door cavity in an edge of the door adjacent the door jamb, an expansible, sealed chamber within the cylinder in which a damping piston works, a piston rod connected to the piston and extending outwardly from the chamber towards one end of the cylinder which when the cylinder is mounted in the door is adjacent the jamb, resilient means biasing the piston towards the other end of the cylinder, and connecting means for connecting the piston rod to the doorjamb.
2. A door closer according to claim 1, wherein one end of the chamber comprises a movable seal which permits expansion of the chamber 3. A door closer according to claim 2, wherein the piston rod passes sealinglythrough said seal.
4. A door closer according to claim 2 or 3, wherein the seal is resiliently biased in a direction to reduce the chamber volume.
5. A door closer according to any of claims 1 to 4, wherein the outer end of the piston rod is supported by a support within the cylinder.
6. A door closer according to claim 5, wherein
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