Patent Application
20050285092
The present invention relates to safety locks for fence posts of fences for swimming pools.
Flexible fences are known, to provide an extra measure of protection in addition to typical chain link fences around a swimming pool, which can sometimes to climbed by young children. The flexible fences are too loose for gripping, and therefore prevent a young child from getting unsupervised access to a swimming pool, even if the child climbs over a conventional chain link fence around a swimming pool. Such flexible fences are described in U.S. Pat. No. 5,553,833 of Bohen.
In addition, there are fence plugs with expandable wings of sockets for fence poles, such as disclosed in U.S. Pat. Nos. 978,505 of Stewart or 3,159,248 of Biehn. Also quarter turn twist lock posts for fences are described in U.S. Pat. No. 4,007,516 of Coules.
U.S. Pat. No. 4,787,601 of Rybek shows plastic anchor sockets, but they are not expanding.
It is therefore an object of the present invention to provide child-resistant socket and post assembly for a temporary flexible fence post.
A low fence of screen netting is sometimes used as a barrier around a pool to deny access to infants and toddlers. Generally support poles are used which are inserted into permanent holes around the pool to provide a means to erect and take down this temporary fencing as needed. Two considerations in this apparatus are safety and convenience. The fence should be easy to erect and remove while making it difficult for a small child to pull the poles from the holes. A simple locking means, such as a twist lock, is sometimes used to satisfy these two considerations.
This invention provides a twist and lock pole insertion and removal capability. In addition, the initial hole preparation which involves insertion of a pole socket is especially simple with the present invention since no great exertion or tools are required. Since the pole socket and the twist and lock insert which is attached to the pole bottom are injection molded from a plastic resin such as polypropylene, low cost and long corrosion resistance are assured. No moving parts or auxiliary metal elements are required. The lock is positively initiated by a twist motion ranging anywhere from about 30 to 90 degrees after the pole is seated in the pole socket.
The pole socket is a hollow cylindrical shape that is slightly tapered from top to its bottom which has a rectangular keyway cutout. Each socket includes one or more (preferably three) of elongated expansion ribs flexibly attached at their upper ends to the walls of the socket. The ribs have a crossectional shape that increases in thickness toward the bottom of the socket, so that the ribs expand outward to engage the sides of the hole when a pole is inserted.
The twist and lock insert which is attached to the bottom of each pole has a shaft region which is inserted into the pole end as well as a small rectangular plate, smaller in both dimensions than the rectangular cutout at the bottom of the pole socket. The insert is inserted into the pole end leaving some space between the pole end and the distal plate. By rectangular it is assumed that the plate has a shape with two axes, where one axis is longer than the other axis. Therefore the plate can also be rounded and elliptical, as well as rectangular.
Operation involves simply inserting the pole into the expandable pole socket and rotating slightly until the distal plate goes through the keyway cutout at the bottom of the pole socket. A twist of the pole beyond this orientation locks the pole to the pole socket.
There is great resistance to pull out the pole and pole socket from the hole in this position beyond the slight press fit of the top region of the pole socket into the hole. This is because the expandable ribs have been pushed with some force against the side walls of the hole.
By twisting the smooth pole back into registration between distal locking plate and rectangular keyway at the bottom of the socket, it can be easily withdrawn with an upward force. This releases the force of the ribs against the hole wall sides, but the slight press fit of the socket in the hole is enough to ensure retention of the pole socket in the hole while the smooth outer surface of the pole easily moves upward disengaging with the expandable ribs.
With the pole sockets of this invention, hole preparation simply involves pressing in a pole socket into a rigid hole until it seats to its upper collar. The press fit force is not relied upon to keep the socket from being pulled up when the pole is locked, so this can be light fit. It is the force of the expandable ribs against the hole walls that serve this purpose while the side force of each rib against the pole side keeps it centered and upright. It is also the rib force against the hole wall that permits the pole to be rotated while the socket remains stationary.
It can be appreciated that the pole should be of smooth surface such as aluminum tubing or plastic resin. In concrete, the pole sockets can be used directly in bored holes. In soft ground, a rigid cylindrical sleeve must be used as a hole liner; this can be a section of metal or plastic pipe of appropriate inner diameter.
The present invention can best be understood in connection with the accompanying drawings, in which:
In the foregoing description, certain terms and visual depictions are used to illustrate the preferred embodiment. However, no unnecessary limitations are to be construed by the terms used or illustrations depicted, beyond what is shown in the prior art, since the terms and illustrations are exemplary only, and are not meant to limit the scope of the present invention.
It is further known that other modifications may be made to the present invention, without departing the scope of the invention, as noted in the appended Claims.
