Patent Application
20070245918
In the following description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific embodiments which may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural, logical and electrical changes may be made without departing from the scope of the present invention. The following description is, therefore, not to be taken in a limited sense, and the scope of the present invention is defined by the appended claims.
A second screen 137 is positioned on top of the cooling material 135, such that the first and second screens hold the cooling material 135 in position. The screens may be formed of stainless steel or other material compatible with the temperatures and other materials used in the canister. Spacer ring 140 formed of mild steel in one embodiment, is positioned on top of the second screen 137, and provides a combustion chamber 142. The spacer ring may be formed of other materials in further embodiments.
The spacer ring 140 also supports a pellet 143 comprising a pressed aerosol forming composition when ignited. The pellet 143 is formed with a hole or opening 145 that contains an ignition mix 147 that is supported within a bushing 150 fastened at a top end of the canister 120. In one embodiment, the cap is sealed with the canister by means of an annular sealant or sealing ring 152. An ignition primer cap 155 is supported by the bushing 150 above the ignition mix 147 for igniting the ignition mix when struck. In a further embodiment, the pellet 143 may be formed without the ignition mix, and directly ignited by the primer cap.
The bushing 150 has an ignition unit receiving portion 160 that extends from the cap and contains a threaded inner portion for receiving a threaded mating outer portion 161 of the ignition unit 115. The receiving portion 160 and mating portion 161 may couple to each other in other ways, such as friction or snap fit. Such coupling may be permanent or releasable in various embodiments.
The ignition unit 115, which in one embodiment is generally cylindrical in shape, has a firing pin 165 slideably mounted within it. The firing pin is coupled to a spring 167 that is compressed against a ledge 170 within the ignition assembly. The firing pin is formed with a detent, groove or annular depression 172 for receiving a restraining device, such as a ball bearing 175 held within a portion 176 of the ignition unit extending generally transverse to the firing pin. Detent 172 may be annular in one embodiment to allow ease of manufacture, removing the need to properly align the pin 165 prior to insertion of the ball bearing 175. In further embodiments, only a portion of the pin has the detent.
The groove 172 may have angled edges, allowing the ball bearing 175 or other stiff structure to move transversely away from the firing pin when no longer held against it. A restraining clip 177 fastened in the transverse extending portion of the ignition unit holds a formed eutectic 180, against the restraining device 175. The eutectic 180 is selected to deform at a desired temperature, releasing the restraining device 175, allowing the spring 167 to drive the firing pin into the ignition primer cap 155. The primer cap 155 will then fire, igniting the ignition mix 147 and in turn the pellet 143. Aerosol from the pellet 143 passes through the screens and cooling material 135, and cross member spacer 130, breaks open the sealant 128 and exits via exit ports 127. In one embodiment, the ignition temperature of the pellet is approximately 270 to 300° C., or other desired temperature which is a function of the chemical composition and method of preparation of the pellet.
In one embodiment, the bushing 150 is part of the ignition unit, and couples to the canister. The bushing 150 includes the primer and ignition mix, and may be shipped separately from the canister, and assembled when ready to use.
In one embodiment, the pellet 143 is formed of a composition comprising potassium nitrate (67-72), dicyandiamide (9-16), phenolformaldehyde resin (8-12), and potassium benzoate, bicarbonate or hexacyanoferrate (4-12) in various percentages by mass as indicated in parentheses. Various other compositions may be used, some of which are described in U.S. Pat. Nos. 6,042,664 and 6,264,772.
The size of the canister may be varied significantly to provide different amounts of aerosol producing material. In one embodiment, the mating threaded portions where the canister and ignition unit attach are the same size for the various sizes of canisters. Thus, a canister designed for inside a cabinet may be fairly small, such as smaller than a can of soda. Canisters designed for larger applications, such as retarding fires in a room, may be very large, All the canisters may use the same size ignition unit provided they are designed to attach to each other through the use of mating threaded portions, or other physical coupling mechanisms.
A top view of the ignition unit 115 is shown in
The slot is positioned to hold the retaining clip, shown in detail in
With the eutectic 180 formed or shaped as shown in
The Abstract is provided to comply with 37 C.F.R. §1.72(b) to allow the reader to quickly ascertain the nature and gist of the technical disclosure. The Abstract is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.
