Sprinkler with motion limited lever

A sprinkler of the compressed strut and lever type wherein the motion of the lever is limited is disclosed. The sprinkler includes a compression member that compresses a strut against a sealing member that closes the outlet of the sprinkler. One end of a lever is positioned between the compression member and the strut. The opposite end is positioned in proximity to an abutment surface on the sprinkler. The opposite end is engageable with the abutment surface which limits motion of the lever and maintains an offset between the strut and the compression member that renders the strut and lever an unstable mechanism. A frangible link extends between the strut and the lever. The link separates in response to an increase in temperature indicative of a fire condition.

FIELD OF THE INVENTION

This invention relates to sprinklers for fire suppression systems having compressed lever and strut triggering mechanisms.

BACKGROUND OF THE INVENTION

Of the various types of sprinklers used in fire suppression systems, the compressed lever and strut variety finds extensive use. Compressed lever and strut sprinklers use an inherently unstable trigger mechanism comprising a compression member that compresses a strut and lever against a sealing member which closes the outlet of the sprinkler. The strut is positioned lengthwise between the compression member and the sealing member, and the lever is positioned between an end of the strut and the compression member. The strut has a line of action that is offset from the line of action of the compression member. This offset allows the compression member to induce a torque in the lever, which, if unrestrained, would rotate away from the strut, causing the strut to disengage from between the compression member and the sealing member and allow the sprinkler to open. A frangible link extends between the strut and the lever, normally preventing rotation of the lever. The link separates in response to an increase in the ambient temperature indicative of a fire, thereby allowing the lever to rotate and displace the strut from between the compression member and the sealing member, releasing the sealing member and opening the outlet. Fire suppressing liquid may then flow through the sprinkler to contain and extinguish the fire.

For proper functioning of the sprinkler, the trigger mechanism must remain unstable. It is observed however, that a force applied to the free end of lever tending to move the end toward the strut will shift the line of action of the strut, causing it to align with the line of action of the compression member. When this occurs, the mechanism becomes stable, there is no torque on the lever and the link is no longer under tension and is not needed to hold the lever in position. When a temperature increase from a fire causes the link separate, the strut and the lever remain in position between the compression member and the sealing member, holding the sealing member in position closing the sprinkler outlet. In this situation, the sprinkler fails to open and discharge water and the fire propagates. The force applied to the lever which renders the trigger mechanism stable may occur as a result of improper handling during shipping or installation. The mechanism may also be rendered stable due to improper assembly at the factory. It is, furthermore, very difficult to visually detect whether a trigger mechanism is in a stable or an unstable condition. There is clearly a need for an improved sprinkler of the compressed lever and strut type which does not suffer from this disadvantage.

SUMMARY OF THE INVENTION

The invention concerns a sprinkler for a piping network of a fire suppression system. The sprinkler comprises a body having an inlet connectable to the piping network and an outlet in fluid communication with the inlet. A compression member is mounted on the body and is positioned in facing relation with the outlet. The compression member has a first line of action extending toward the outlet. A sealing member closes the outlet. A strut extends lengthwise between the compression member and the sealing member. The strut has a second line of action that is offset from the first line of action of the compression member. A lever has a first portion that is positioned between the strut and the compression member. The lever also has a second portion spaced from the first portion. The body has an abutment surface engageable with the second portion of the lever. Engagement of the second portion with the abutment surface limits motion of the lever toward the strut so as to maintain the offset between the first and second lines of action of the strut and the compression member. A link attaches the lever to the strut. The link is frangible, and when heated to a predetermined temperature, releases the lever from the strut. The strut thereby disengages from the sealing member, allowing the sealing member to disengage from the outlet to permit fluid flow from the sprinkler.

The invention also includes a fire suppression system comprising a piping network to which one or more of the above described to sprinklers are attached.

The invention further includes a method of maintaining an offset between a first line of action of a compression member and a second line of action of a strut. The method comprises:(A) providing a lever;(B) positioning a portion of the lever between the strut and the compression member;(C) compressing the lever between the compression member and the strut;(D) providing a link between the lever and the strut, the link preventing motion of the lever away from the strut;(E) providing an abutment surface engageable with the lever, the abutment surface limiting motion of the lever toward the strut.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1shows a sprinkler10according to the invention. Sprinkler10comprises a body12having an inlet14threadably connected to a piping network16of a fire suppression system18. The piping network conducts water or other fire suppressing fluid from a source of pressurized fluid20to the sprinkler, which opens in the event of a fire to extinguish the fire and prevent its propagation.

As best shown inFIG. 2, body12has an outlet22in fluid communication with inlet14. The outlet faces a deflector plate24mounted on a housing26supported by legs28that extend from body12. Housing26receives a compression member30, for example, a threaded stud32that engages internal threads within the housing and is thus movable toward and away from the outlet22upon rotation of the stud.

A sealing member34, for example, disk36, closes outlet22. The sealing member34is held in position by a strut38that is compressed against the sealing member by the compression member30acting in conjunction with a lever40. Lever40has a first portion40apositioned between one end of strut38and the compression member30, the opposite end of the strut engaging the sealing member34. Note that the strut and the lever are both separate components which are not fixed to each other, the sealing member, or the compression member.

Compression member30has a line of action42, corresponding substantially to the centerline of the threaded stud32. Similarly, strut38has a line of action44which generally corresponds to the strut centerline. The strut line of action44is offset in relation to the line of action42of the compression member30. The offset may comprise an angular offset46as shown, effected by angularly orienting the strut38relatively to the compression member30. When the compression member is advanced, the lever portion40ais compressed against the strut38and the strut is compressed against the sealing member34(disk36in this example). Because there is an offset46between the lines of action of the compression member30and the strut38, the compression force induces a torque on lever40. The strut38is offset toward the lever40such that the torque acts to rotate the lever outwardly away from the strut.

Another portion40bof the lever40is in spaced relation away from end40a. Lever portion40bpreferably extends upwardly alongside strut38to permit a link48to extend between the strut and the lever. Link48is shown in detail inFIG. 3. As best shown inFIG. 2, link48is formed by two plates50and52soldered to each other in facing relation using a solder with a predetermined melting temperature. One of the plates,50, engages the strut, the other,52, engages the lever. As long as the solder joint remains intact, link48prevents lever40from rotating outwardly away from the strut38under the torque induced by the compression of the lever and the strut by the compression member30.

In operation, with the sprinkler10mounted on the piping network16as shown inFIG. 1, the lever40is subjected to torque but is prevented from rotating by link48, which is under tension. During a fire, when the ambient temperature surrounding the sprinkler10reaches the melting point of the solder holding the plates50and52of the link48together (seeFIG. 2), the solder melts. The link can no longer withstand the tension, the plates separate and the torque on lever40causes it to rotate outwardly away from strut38. Upon rotation of the lever, the strut38is dislodged and falls away from the sprinkler, no longer supporting sealing member34, which falls away from the outlet thereby allowing water or other fire suppressing fluid to be discharged from the sprinkler head.

The lever40and strut38, when compressed between the compression member30and the sealing member34, constitute an unstable trigger mechanism held in place by the separable link48. The instability is due to the offset46of the line of action44of the strut38relatively to the line of action42of the compression member30which causes a torque to be induced on the lever by the applied compression force. For proper functioning of the sprinkler10the mechanism must remain unstable. It is observed, however, that a force applied to the end40bof lever40tending to move the end40btoward the strut38will shift the line of action44of the strut, causing it to align with the line of action42of the compression member34. If this is permitted to occur the mechanism becomes stable, there is no torque on the lever, and the link48is no longer under tension. When a temperature increase from a fire causes the solder holding the plates50and52of the link to melt, the plates separate but the lever and the strut remain in position between the compression member and the sealing member, holding the sealing member34in position closing outlet22. In this situation, the sprinkler10fails to open and discharge water and the fire propagates.

To prevent the trigger mechanism from becoming stable, the body12has an abutment surface54. Abutment surface54is located between the strut38and the end40bof lever40, and these two elements are mutually positioned to cooperate with one another and limit the motion of lever40toward the strut38. In the example embodiment shown inFIG. 1, the lever40extends angularly from end40aso as to position opposite end40bin close proximity to the abutment surface54, which comprises a flat56on the body12adjacent to the outlet22. The lever end40bmay be in spaced relation to the abutment surface as shown inFIG. 2, or it may be in contact with the surface, as shown inFIG. 4.

In another embodiment, shown inFIG. 5, the abutment surface54may be located on a projection58that extends from the body12. The projection58allows a shorter lever40to be used but still allows cooperation between the components to limit lever motion and ensure mechanism instability. The lever end40bmay be in spaced relation to the abutment as shown inFIG. 5, or in contact with it, as shown inFIG. 6.

Use of the abutment surface in cooperation with the lever limits motion of the lever so as to avoid shifting of the line of action of the strut which might otherwise eliminate the offset necessary to the proper functioning of the sprinkler. Additionally, the abutment surface will facilitate assembly of the trigger mechanism as it provides a positive stop for ensuring proper positioning of the lever relatively to the strut.

Sprinklers of the compressed lever and strut type further having an abutment surface engageable with the lever according to the invention provide a more reliable sprinkler which will not become inoperative due to improper assembly or handling during shipping and installation.