1. Field of the Invention
This invention relates to tension rods, and in particular to tension rods for expanding against opposite walls or other support surfaces for holding curtains, hangers or other articles in place on the tension rod.
2. Description of the Prior Art
Tension rods incorporating telescoping tubes for being installed between walls having different distances between them are well known in the art. Typical tension rods are known for hanging shower curtains. A number of such rods are known having long coil compression springs which are compressed as the telescoping tubes are pressed together and then released so the spring can expand and press the tubes against the walls. However, those rods show the least amount of tension force when the spring is in its expanded state when advantageously it should have its greatest strength, and show the highest tension force when the spring is in its compressed state. In some cases, threaded inner and outer rods are known. However, such of the rods often require a great number of rotations to get the desired length, and often cannot maintain a tight enough fit over time to maintain the rod in place, essentially under downwardly transverse loads. Such constructions are described in U.S. Pat. No. 704,403 (Thill), U.S. Pat. No. 2,079,267 (Vroom), U.S. Pat. No. 2,919,134 (Zuro) and U.S. Pat. No. 3,521,758 (Guilfoyle, Sr.). In some instances a biasing spring is combined with combinations of threaded rods, such as in U.S. Pat. No. 670,585 (Fowler), U.S. Pat. No. 856,316 (Thurston), U.S. Pat. No. 1,548,053 (Mead), U.S. Pat. No. 2,199,851 (Culver), CH 625601 (Baumann) and JP 2055100 (Wada), but these have not been found effective. Compression spring arrangements in tension rods are very well known, but involve a compromise in being reasonably easy to compress while providing sufficient holding force to keep the tension rod in place between opposing walls while the tension rod is under downward transverse loads. This type of tension rods area disclosed in U.S. Pat. No. 468,987 (Lingley et al.), U.S. Pat. No. 519,840 (Edsall), U.S. Pat. No. 536,272 (Edsall), U.S. Pat. No. 645,543 (Birch), U.S. Pat. No. 647,986 (Roberts), U.S. Pat. No. 841,062 (Snyder et al.), U.S. Pat. No. 961,352 (Walters), U.S. Pat. No. 988,200 (Logsdon), U.S. Pat. No. 1,140,570 (Buckley), U.S. Pat. No. 1,178,994 (Crump), U.S. Pat. No. 1,425,247 (Galbreath), U.S. Pat. No. 1,639,551 (Booth), U.S. Pat. No. 2,032,842 (Gould), U.S. Pat. No. 2,519,996 (Blake), U.S. Pat. No. 2,973,870 (Schoos), U.S. Pat. No. 3,350,120 (Hinrichs), U.S. Pat. No. 3,952,877 (Kindl), U.S. Pat. No. 4,6037,726 (Schweers), U.S. Pat. No. 4,147,199 (Cameron), U.S. Pat. No. 5,242,065 (Hoban) and U.S. Publication Nos. 2008/0156952 (Nathan) and 2009/0101609 (Batshon). A flexible threaded rod without a spring is disclosed in U.S. Pat. No. 5,330,601 (Geltz). Rods are also known which are initially put between opposing walls, and later tightened against those walls. This can be difficult to do where there is no easy access between the walls and may not produce a tight fit. Other tension rods exist where the rods tend to “walk” or slip as outward tension force is applied to the tension rods.
None of the foregoing patent disclosures discloses a compression coil spring in a tension rod which maintains nearly constant tension before, during and after the tension rod is installed. No tension rods are known where a compression spring is located in a holding device disposed in one of a pair of telescoping tubes, wherein the tubes are compressed using low manual force, then twisting one of the tubes to tightly lock the compression spring in place, and then releasing the tubes between the walls. The present invention lacks the shortcomings of the prior art, including long compression springs, compression springs whose springs vary from being relatively high when in a compressed state and relatively weak in an expanded state. The present invention in its preferred form is easy for the average person to compress when required for installation, as is not true for the tension rod having a flexible worm gear for providing the tension force rather than a spring. Tension rods according to the preferred embodiments of the present invention do not tend to “walk” or slip along the surface during installation.