Protective valve cap

A protective cap for a threaded valve stem includes a generally cylindrical portion including a closed end, an open end and a cylindrical wall portion therebetween. A plurality of locating ribs are located on an internal surface of the cylindrical wall portion. A plurality of fingers project radially inward from the internal surface between the locating ribs. A tear strip formed by two frangible members, and a pull tab are formed on an external surface of the cylindrical wall portion. Each finger is located between a pair of the locating ribs and has a flexible portion adjacent the internal surface for locating the fingers in unlocked state and a locked state. The fingers in the unlocked state are inclined toward the open end, and the fingers in the locked state curl toward the closed end.

BACKGROUND OF THE INVENTION

1. Field of Invention

This invention relates to a protective cap for a threaded valve stem. In particular, the application relates to a tamper resistant, easily removable, protective cap for a propane gas tank valve stem, that provides the purchaser with a convenient visual identification that the tank is full.

2. Description of Related Art

Conventionally, for propane valves, for example, new QCC propane valves, labels are used to indicate when a propane tank has not been used or has been filled with propane. With the tanks stored outside, for example, the labels are exposed to rain, snow, wind and the like, which may cause the labels to eventually degrade or fall off. In addition, the labels can be easily manually removed from the valve. Therefore, it is difficult to make sure that the propane in the tank has not been used. Furthermore, with such labels, if the tanks are stored outside, dust and/or dirt may build up on the valve. As such, more protection is needed for the propane valves for security and contamination purposes.

U.S. Pat. No. 4,712,705 to Fuehrer discloses a tamper indicating cap seal for container valves. The cap includes an upper body portion which is securely engagable over a valve and completely covers a plug of the valve, a lower skirt portion attached to the upper body that covers lower part of the valve, and a plurality of teeth that are formed inside the upper body to fit in inclined surfaces of the valve to provide locking of the cap onto the valve. The cap also includes a tear strip member constituted by a pair of spaced and parallel weakened grooves formed inside the cap, and a tab attached to the tear strip member, to indicate that the cap has not been removed or tampered and to allow easy removal of the cap from the valve by pulling the tab to break the weakened grooves. The grooves provide vents for escape of air to avoid the trapping of air in the end of the cap when the cap is rapidly pushed into the plug.

However, because the teeth must be made to fit on the inclined surfaces of the valve, the cap must be specifically produced for the valve.

SUMMARY OF THE INVENTION

Accordingly, a cap is desired that can be used on different shapes of valves and that can be tamper-evident and protective. Thus, it is an object of this invention to provide a protective cap for a valve stem that can easily fit on the valve and increase the protection from tampering, while a seal of the cap is easily broken such that the cap can be easily removed from the valve.

A protective cap for a threaded valve stem according to this invention includes a generally cylindrical portion including a closed end, an open end and a cylindrical wall portion therebetween, the cylindrical wall portion having an external surface and an internal surface, a plurality of locating ribs located on the internal surface, and a plurality of fingers projecting radially inward from the internal surface. Each finger is located between a pair of the locating ribs and has a flexible portion that is adjacent the internal surface for locating the fingers in an unlocked state and a locked state. The fingers in the unlocked state are inclined toward the open end, and the fingers in the locked state curl toward the closed end.

The protective cap of this invention may further include a pair of frangible members located on the external surface and extending between the closed end and the open end to define a tear strip, and a pull tab connected to the tear strip at the open end. The pair of frangible members may be located between a pair of corresponding locating ribs.

These and other objects, advantages and salient features of the invention are described in or apparent from the following detailed description of exemplary embodiments.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 1,2A,3and4show an exemplary embodiment of the protective cap according to this invention.FIGS. 2B and 2Cshow an alternative embodiment for a pull tab and tear strip.

As shown inFIG. 1, a protective cap100may be made of thermoplastic resin that is injection molded. The cap100has a generally cylindrical wall portion101, a closed end102and an open end103. At the closed end102, the word “Full” or the like may be shown on an external surface to indicate that the propane tank has not been used. Also on the closed end102, a warning message and/or safety information may be shown. The cylindrical wall portion101preferably has a constant diameter but other shapes are possible.

On an internal surface of the cylindrical wall portion101, a plurality of locating ribs104are formed, which locate a valve200(seeFIG. 3) to be inserted into the center of the protective cap and to distance the valve200from the internal surface of the protective cap as shown in FIG.4. In the exemplary embodiment, there are eight locating ribs, which are preferably formed symmetrically around the internal diameter of the cap. However, this number is not limited to eight. It may be appreciated by those skilled in the art that any number of the ribs may be possible, and that the ribs may not be formed symmetrically.

The locating ribs104extend from the open end103to the closed end102and provide strength to the protective cap100when the valve100is inserted into the protective cap100. The locating ribs104have a height (in the radial direction of the cap) that provides sufficient spaces150between threads201of the valve200and later-described platforms107, as shown inFIG. 4, such that retaining fingers105can sufficiently curl when the threads201of the valve200are inserted within the cap. In addition, the locating ribs may have a round surface and terminate near the open end so that the valve200may be inserted easily.

The retaining fingers105are formed between the locating ribs104. The retaining fingers105are formed radially inward from the internal surface of the cylindrical wall portion101and may be inclined towards the open end when the valve200is not inserted (unlocked state) as shown in FIG.1. As shown inFIG. 2A, each finger105may be formed to have a round end and may be made to extend beyond the height (in the radial direction) of the locating ribs104. Each finger105has a flexible portion106formed adjacent to the internal surface of the cylindrical wall portion101. The flexible portion106provides flexibility, such that the finger105can sufficiently bend and curl when the valve200is inserted (locked state) as described later.

Each finger105may be formed on a platform107(FIG. 1) formed on the internal surface of the cylindrical wall portion101. Each platform107is formed to provide a sufficient clearance for the fingers105, when molding the protective cap100. In addition, the platforms107extend to the closed end102and provide strength to the protective cap100and support for forces applied to the fingers105when the valve200is inserted into the protective cap100. However, it will be appreciated by those skilled in the art that if desired, the platforms107may be omitted.

On the external surface of the cylindrical wall portion101, a pair of frangible members108are formed to extend in the entire length of the cylindrical wall portion101, i.e., from the closed end102to the open end103, to constitute a tear strip109. The pair of frangible members are formed between a pair of the locating ribs104but outside of the platform107, as shown in FIG.2A. In the exemplary embodiment of this invention, the frangible members108are formed on the external surface of the cylindrical wall portion101and have a V-shape. However, it is apparent for those skilled in the art that the frangible members108may be formed on the internal surface of the cylindrical wall portion101and may have a U-shape or the like. As illustrated inFIGS. 2B and 2C, the frangible members108may extend onto the top of the cap. Any arrangement of the frangible members108is possible to define different shapes of the tear strip109. As described below, breaking of the frangible member108splits the cap for removal from the valve stem. Once the frangible members are broken, the cap is destroyed and incapable of re-use.

As shown inFIGS. 1 and 2A, a pull tab110is formed on the external surface of the cylindrical wall portion101and connected to the tear strip109. In the exemplary embodiment, the pull tab110is formed perpendicular to the cylindrical wall portion101. However, the pull tab110may extend in any direction along the cylindrical wall portion101. The pull tab110may also take different forms and shapes, as illustrated inFIGS. 2B and 2C. Furthermore, in the exemplary embodiment, there may be formed a wide grip portion111and/or bumps112to enhance gripping by a user. Therefore, by pulling the pull tab110, the frangible members108break, and thus the diameter of the cylindrical wall portion101expands. As a result, the fingers105are released from the valve threads, allowing the protective cap100to be removed from the valve200.

Next,FIGS. 5-8show operation of the fingers105.

FIG. 5shows an unlocked state in which the valve200is not inserted into the protective cap100. At this time, the fingers105project radially inward from the internal surface of the cylindrical wall portion101and are inclined towards the open end103.

As shown inFIG. 6, when the valve200is inserted into the protective cap100, the threads201of the valve200slide on the locating ribs104and thus position the valve in the center of the protective cap100. The front end of the valve port202engages with the fingers105. As the valve200is further inserted, the fingers105are pushed by the valve port202towards the closed end102, and therefore, the flexible portions106of the fingers105start to flex to allow the fingers105to curl toward the closed end.

As shown inFIG. 7, the fingers105are bent flat at the flexible portions106when the threads201come over the fingers105. At this time, because of the locating ribs104, there are spaces150between the threads201and the platform107for the fingers105to fall in (see FIG.3).

FIG. 8shows a locked state in which the valve200is fully inserted in the protective cap100. At this time, all threads201have past the fingers105. Therefore, because of the reaction force of the flexible portion106, the fingers105abut the valve port202and stay curled towards the closed end102. Since the fingers105are curled towards the closed end102, the fingers105prevent easy removal of the cap, thus providing protection from dirt and contamination which also protects the valve threads. Because of the curl, the fingers prevent easy removal of the cap because the fingers are locked under the threads. To remove the cap, the user must pull the tab110, to break the frangible members108that define the tear strip109. Pulling on the tab110removes the tear strip109and splits the cap, which separates the fingers from the threads and thus allows the cap to be removed. A valve without a cap or a valve with a damaged cap provides a visual indication of tampering. Further, the cap is destroyed by pulling the tab and removing the tear strip, so the cap cannot be re-used. Customers seeing an undamaged cap on the valve thus know that the tank is full.

It is noted that the cap may have indicia on the top exterior surface to indicate that the tank is full. Safety information and/or warning messages may also be shown on the top exterior surface. Removal instructions or indicia may appear on the pull tab. Those skilled in the art recognize that the indicia and its location on the cap or tab may be changed from the exemplary embodiments.

While the invention has been described in conjunction with the specific embodiments described above, many equivalent alternatives, modifications and variations may become apparent to those skilled in the art once given this disclosure. Accordingly, the exemplary embodiments of the invention as set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.