Fireproof smoke damper

Abstract

A fireproof smoke damper having a casing or duct which includes a curved sector and a shutter plate within the sector and pivoted at the center of curvature thereof.

Description

This invention relates to a fireproof smoke damper for use in the ventilation system of a building.

When a fire breaks out in a room of a building, smoke and flame produced by the fire are transferred to other rooms and to the outside of the building through exhaust ducts of the ventilation system. This not only obstructs fire-fighting and sheltering action but also promotes the spread of fire. Many types of dampers have been used with a ventilation duct but the prior dampers have commonly employed a butterfly-type shutter plate rotatably supported on a shaft in a straight tubular damper casing. Such types of prior damages have gaps between the shutter plates and the casings for the purpose of preventing interference with the operation of the damper due to rusting of the rotating portion and contamination with dust. As a result, sufficient interception of smoke and flame cannot be obtained because the closed damper is not air-tight.

Accordingly, an object of this invention is to provide a novel and improved fireproof smoke damper which overcomes the abovementioned disadvantages of the prior dampers and will effectively prevent the passage of smoke and flame into ventilation and other ducts.

The damper according to this invention includes a damper casing having a longitudinal section at least a part of which is composed of a sector and a shutter plate rotatably supported at one edge by a shaft positioned at the center of said sector.

Other features of the operation of this invention will be described in detail hereinunder with reference to the accompanying drawings.

In the drawings:

FIG. 1 is a cross-sectional view of an embodiment of a smoke damper according to this invention; and

FIG. 2 is a schematic diagram, partially in block form, representing the damper of FIG. 1 and means for the operation thereof.

Throughout the drawings, like reference numerals are used to denote corresponding structural components.

Referring to FIG. 1, the damper of this embodiment has an L-type casing 1 consisting of a straight upright portion 11, a curved elbow portion 12 and a straight horizontal portion 13. The upright portion 11 is connected to a ventilation duct 2 and the horizontal portion 13 is connected to a suction hood 3 positioned within an opening formed in the wall 4 of the building. The elbow portion 12 is a curved section having a central angle .theta. which is equal to 90.degree. in the present embodiment. A horizontal rotating shaft 21 is supported at the center of the sector or curved section of the elbow portion 12 and a flat shutter plate 20 having a contour corresponding to the cross-section of the elbow portion 1 is supported at one edge by the shaft 21. The shutter plate 20 is rotatable about the shaft 21 between the closed position 20 as shown and the opened position 20' as shown in phantom. Thus, the shutter plate 20 can completely close the elbow portion 12 with the central angle .theta.. A flow-rate control 30 having shutter wings 31 and a face grid 32 is positioned in the suction hood 3.

Referring to FIG. 2, the damper shaft 21 is coupled through a crank arm 22 to a piston rod 41 of an air cylinder 40 having a piston 42 which is always held in the lowermost postion by a spring 43. An air inlet port 44 attached to the bottom of the cylinder 40 is connected through a hose 5 to an outlet port 51 of an electromagnetic air valve 50. The air valve 50 also has an air inlet port 52 connected through a hose 6 to a compressed air source such as an air compressor (not shown) and an air exhaust port 53. The cylinder of the electromagnetic air valve 50, includes an armature 55 which is actuated by an electromagnet 54 and a piston 56 is fixedly coupled through a connecting rod 57 to the armature 55. The armature 55, piston 56 and respective ports 51, 52 and 53 are arranged so that the ports 51 and 52 communicate when the armature 55 is actuated and the ports 51 and 53 communicate when the armature 55 is deactuated. The electromagnet 54 of the air valve 50 is connected to a power source (not shown) through a main control switch board 60 including a main switch 61 and a test switch 62, a local control switch board 70 including a thermostat switch 71 and a test switch 72 and a fuse box 80 including a fuse 81. The main control switch board 60 is installed in the central control room and has a plurality of branch lines for feeding to the other dampers though they are omitted from the drawing for the purpose of simplification. The local control switch board 70 is installed near each damper and the fuse box 80 is installed in the damper casing 1.

When the main switch 61 is closed, the electromagnet 54 of the air valve 50 is energized to pull up the armature 55 and of the piston 56. Thus, the ports 51 and 52 communicate to feed a compressed air to the air cylinder 40 through the hoses 6 and 5 from the compressed air source (not shown). The piston 42 is pushed up against the spring 43 to rotate the crank arm 22, upwardly and maintain the shutter plate 20 of the damper in the open position 20' (FIG. 1).

When the main switch 61 is opened manually in the case of fire, the electromagnet 54 is de-energized and the piston 56 falls under its own weight with the result that the ports 51 and 53 are placed in communication. Accordingly, the air in the air cylinder 40 is exhausted through the hose 5 and the port 53 and the piston 42 is pushed downwardly by the spring 43 to rotate the shutter plate 20 to its counterclockwise position to close the damper. The same damper closing action also occurs in response to opening of the switches 62, 71 or 72 or opening of the fuse 81 by excessive heat or other reason. The operation and objects of these switches are self-explanatory.

As previously described, the damper of this invention is fully closed as long as the shutter plate 20 is within the central angle .theta. of the sectorial or curved section of the elbow portion 12. A cam 90 fixed to the rotating shaft 21 of the shutter plate 20 is shaped so that it actuates a switch 91 only when the shutter plate 20 is within the central angle .theta.. The switch 91 is connected in an indicating lamp circuit (not shown) to indicate sufficient closure of the damper.

Although, in the above embodiment, the damper is connected to a vertically extending ventilation duct and, therefore, the shutter plate 20 of the damper is opened upwardly about the horizontal shaft 21, the damper of this invention may also be applicable to a horizontally extending duct. In this case, the shutter plate of the damper is arranged to rotate about a vertical shaft similar to a door and is closed only by the spring force of the air cylinder 40, while, in the former case gravity supplements the action of the spring.

As above described, the damper of this invention can sufficiently intercept smoke and flame even if some deviation takes place in the position of the closed shutter plate and, therefore, exhibits a high degree of safety and reliability over the prior art dampers.

It should be noted that the above description has been made in conjunction with the illustrated embodiment only and various changes and modifications may be made without departing from the scope of the invention as defined in the appended claim.

Claims

I claim:

1. A fireproof smoke damper assembly comprising a duct having a substantially straight section and a curved elbow section joined one to the other, said curved section having a longitudinal section in the form of a sector of a circle having its center at one side of said duct, a shaft on said one side of said duct and substantially coincident with said center and a damper plate attached along one edge to said shaft for rotation within said duct about said center, said damper being movable from an open position lying against a wall of said straight section to closed positions when disposed at any point within said curved section and is in close proximity with the wall of said curved section.

2. A fireproof smoke damper according to claim 1 including an arm carried by said shaft, a cylinder including a spring loaded piston, a rod coupling said arm to said piston whereby said piston under the action of said spring will normally hold said damper in the closed position, means including an electrically operated valve for feeding a fluid under pressure to said cylinder, said valve upon being energized permitting fluid pressure to act on said position and move it in opposition to said spring to open said damper and means on said valve for interrupting said fluid pressure upon de-energization and permit discharge of said fluid in said cylinder and said piston to move said damper to the closed position.

3. A fireproof smoke damper according to claim 2 including a power switch, a thermostatically controlled switch and at least one test switch connected in series one with the others and with said electrically operated valve for controlling the application of energy to said valve.

4. A fireproof smoke damper according to claim 3 wherein a heat responsive fuse is positioned within said damper casing and connected in series with said switches.