1. Field of the Invention
The present invention relates to closures for chambers and, more particularly, to apparatus for moving the door of a chamber to and from its closed position.
2. Description of the Prior Art
There exists a wide variety of chambers adapted for maintaining pressure within the chamber. An example of such a chamber is a sterilizer that operates under pressure during at least a portion of the sterilizing cycle. To enable pressure to build within the chamber of the sterilizer, it is necessary to provide a seal against fluid flow from the chamber between the perimeter of the chamber opening and the door of the sterilizer. Typically, such a seal is effected by disposing a sealing device between the perimeter of the opening and the door. The sealing device is usually disposed on either the perimeter of the opening or the chamber door. Generally, one of two types of sealing devices is used to effect the fluid seal. The first, a compression seal, requires that compressive force be exerted on the seal by the door and the perimeter of the opening to the chamber. The second type of seal, a noncompressive seal, does not require the exertion of such a compressive force, but requires only that the seal contact the surfaces of both the perimeter of the opening and the door.
Moreover, for reasons related to personnel safety, it is necessary to ensure that a buildup of pressure cannot be established inadvertently within the chamber of a sterilizer.
Conventional closures for such sterilizers generally comprise a cluster of radial arms or bolts which are attached to a circular hub upon which a threaded nut is mounted. The nut travels along a threaded door post which is mounted on the door plate. The door is closed tightly against the chamber by rotating through several revolutions a handwheel that is mounted on the threaded nut to push the door post and door against the perimeter of the chamber opening. Such conventional closures are bulky and expensive to manufacture; further, the operator must use both hands to exert sufficient force on the handwheel to close a sterilizer door. Use of such conventional closures consumes a relatively long period of time since the operator must rotate the wheel completely several times to close the door.
Accordingly, there exists a need for apparatus for closing the door of a chamber capable of maintaining pressure within the chamber, such as a sterilizer, that can be operated quickly by one hand and with relatively little force and that prevents a user from inadvertently causing pressure to build within the sterilizer.
Fraser U.S. Pat. No. 272,873, issued on Feb. 27, 1883, and Kerr U.S. Pat. No. 2,481,429, issued on Sept. 6, 1949, disclose closures for openings. Although those closures employ some features of the present invention, they lack several features critical to the operation of the present invention.