Long hoses containing compressed air present a danger when they are suddenly disconnected from the compressed air source. The sudden disconnect of the hose can be intentional or may be due to a break, but the result is the same: the air exits forcefully causing the hose to fling around with great force possibly causing injuries to people or damage to objects in their vicinity.
Check valves can be used to prevent such sudden decompression but such valves are designed to prevent 100% of the back flow. This property presents a problem: typically when a compressed air hose is disconnected, it is usually rolled to be stored away in a compact form. If the compressed air in the hose is not evacuated, the hose cannot be rolled away. Ideally what is needed is a leaky check valve.
U.S. Pat. No. 2,940,470 by Morgan relates to check valves of the type which open only under pressure from one direction but once opened will remain open to permit flow in the opposite direction until the opening pressure drops to a determined minimum. This check valve is not designed to bleed off compressed air.
U.S. Pat. No. 4,060,219 by Crawford describes a quick disconnect system for insertion in compressed air system wherein means are provided to hold an associated male plug in a manned such that the plug is securely held and, if an attempt is made to withdraw the plug by pulling the plug out, the hold upon the plug tends to tighten by wedging a steel ball into a smaller and smaller area. This invention is not designed to gradually bleed off the compressed air.
U.S. Pat. No. 4,418,716 by Starke is a two way flow valve in which a fluid from an input port is directed to flow along two paths to a common outlet port. This two-way valve is not designed to gradually bleed compressed air.
U.S. Pat. No. 5,290,009 by Heilmann describes a self-venting rapid connection-release coupling for compressed gas lines, in which the pressure from the compressed air locks the coupling and prevents its release unless the compressed air is vented. This invention does not operate to allow the slow release of the air pressure after the coupling is disconnected.
None of the prior art offers the functionality, safety features, simplicity and economy of use of this invention. Further features, aspects, and advantages of the present invention over the prior art will be more fully understood when considered with respect to the following detailed description claims and accompanying drawings.
The check valve described in this invention prevents the sudden decompression of air contained in a compressed air hose while allowing the air to exit at a safe and slow rate. Essentially, this invention is a leaky check valve. It comprises:
When the fluid flow is in the forward direction, that is, from the inlet to the outlet, the ball is pushed against the ball restraint and the fluid flow is essentially not obstructed by the ball. When the fluid flow is in the reverse direction, that is, from the outlet to the inlet, the ball is pushed against the annular valve seat. The fluid flow is partially obstructed by the ball: the grooves in the seat allow slow leakage of the fluid.
Variations to this basic theme include the implementation of the valve seat and ball restraint typically made of plastic, by means of an insert that fits inside the cylindrical connector. This insert comprises:
The valve seat, bars, and segmented ring essentially form a cylindrical cage enclosure which holds the ball.
To hold the insert in place within the connector, a detent mechanism can be used. For example, the split ring can be shaped on its periphery with a protuberance, matching in shape a groove located on the internal surface of the cylindrical connector. The bars linking the seat to the split ring segments can be made flexible enough to allow them to bend when the insert is pushed inside the connector. Flexible bars can also be useful to allow the ball to be placed into the insert.
The cylindrical connector can be made with various couplings on its inlet and outlet ends. For example the inlet can be threaded as a male and the outlet as a female or vice versa. In addition both inlet and outlet can be threaded as males or both can be threaded as females.
The detent mechanism on the insert may be eliminated by relying on the coupling to perform the retention of the insert. For example, a male plug screwed into a female port of the connector can hold the insert in place.
The split ring can be divided into a number of segments, for example three or four segments. In addition, the number of groves on the annular valve seat can vary. For example there may be three grooves or four grooves or any convenient number of grooves. The depth of the grooves will determine the rate of back flow of the air. Grooves ranging from 0.005 inches to 0.01 inches in depth are most convenient. However, it is possible to have grooves ranging from 0.001 inches to 0.04 inches in depth. It all depends on the desired rate of backflow.
An off the shelf compressed air connector can be adapted to operate as a leaky check valve: grooves can be chiseled on the inside of the connector to provide a means for the compressed air to leak out, and ball restraint can be formed by obstructing the outlet with a bar traversing the connector near the outlet side.
This invention is illustrated in the cross-sections diagrams shown in
The central area of the connector 1 consists of a cylindrical space 4 into which fits the second part of the invention, an insert 5, typically made of plastic and shown in detail in
The third part of the invention is a ball 13 made of plastic or metal that fits inside the cage formed by the insert 5 as shown in
The connector can be of a strong material such as metal, for example brass. The insert and the ball can be made of metal or plastic.
When the device operates as an open check valve as shown in
In closed check valve operation shown in
This leaky check valve device can be attached between a hose and a conventional compressed air plug to prevent a violent discharge of the compressed air when the air plug is suddenly disconnected. After the compressed air has bled off, the hose can be conveniently rolled and stored away.
As is evident to a person having ordinary skills in the art, a number of variations are evident some of which are listed below. The male end 3 and the female end 2 of the connector can be reversed as shown in
While the above description contains many specificities, the reader should not construe these as limitations on the scope of the invention, but merely as exemplifications of preferred embodiments thereof. Those skilled in the art will envision many other possible variations within its scope. Accordingly, the reader is requested to determine the scope of the invention by the appended claims and their legal equivalents, and not by the examples which have been given.
This invention claims the benefit of U.S. Provisional Application No. 60/897,598 entitled “Pneumatic Safety Plug” filed Jan. 26, 2007 and which is hereby incorporated by reference. Applicant claims priority pursuant to 35 U.S.C. Par 119(e)(i). The present invention relates to a safety check valve used with compressed air.
Number | Date | Country | |
---|---|---|---|
60897598 | Jan 2007 | US |