WO1994019058A1

WO1994019058A1 - Locking device for fire-inhibiting shut-off damper

Info

Publication number: WO1994019058A1
Application number: PCT/SE1994/000135
Authority: WO
Inventors: Åke NERELL
Original assignee: Nv Brandstopp Ab
Priority date: 1993-02-17
Filing date: 1994-02-17
Publication date: 1994-09-01
Also published as: SE501148C2; SE9300513D0; AU6120194A; SE9300513L

Abstract

A locking device for a fire-inhibiting shut-off damper, which is opened and closed by means of an electric motor with spring return. The electric motor has a shaft (1), the rotational movement of which is transmitted (3) to a damper plate by means of a pivot arm (2), which has a notch (6) for a lock bolt (7) spring-biased to a locking position. The pivot arm (2) is connected to the drive shaft (1) in such a manner that the drive shaft can be rotated a predetermined angle without moving the pivot arm (2). This makes it possible to move the lock bolt (7), by means of a rocker arm (11) actuated by a segment (13), and a helical spring (10), into or out of engagement with the lock notch (6). The damper is thus, via the pivot arm (2), always locked in the closed position, i.e. when the electric motor is shut off. In order to release the damper, the electric motor must be activated so that the lock bolt (7) is moved to a position out of engagement with the lock notch (6).

Description

Locking device for fire-inhibitinσ shut-off damper

The present invention relates to a locking device for fire- dampers of the type described in the preamble to the subse¬ quent claim 1.

The term "fire-damper" is used for devices mounted in a ven¬ tilation duct and which, in the event of fire with elevated temperature and/or smoke, are to close the ventilation duct so that smoke and fire are prevented from spreading to adja¬ cent parts of a building via the ventilation duct.

The damper plate in a conventional fire-damper is normally made of refractory ceramic material, and it is closed by means of a temperature monitor or a smoke detector with the aid of a spring means, often built-in to a so-called spring return motor. A spring return motor opens the damper plate and keeps it open in normal operation. If there is a power failure or if there is a signal from a fire or smoke detec¬ tor, the spring device is released to close the damper. In a rapidly developing fire, major pressure differences can arise between different portions of a building and it is therefore important that the fire-damper be locked in its closed sealed position.

Swedish patent 8008479-1 reveals as previously known a fire- protecting damper with a closing plate pivotly mounted in a duct portion, said damper having at least one operating mechanism for pivoting the plate. This mechanism comprises an operating rod pivotly joined to the plate, the end of the rod remote from the plate is articulated to the distal end of a crank. The rotational movement of the crank is limited by abutments to end positions lying a few degrees past the two dead center points of the crank movement. This provides a locking of the damper plate both in its completely opened position and in its completely closed position, and release can only be effected by passing the dead center points. The known damper has, to be sure, a function which keeps the shut-off plate in its closed position, due to the fact that the operating mechanism of the plate, after going past the dead center point, is prevented from spontaneously moving back over the dead center point.

If there are powerful vibrations or shock waves arising during a fire, there is, however, still the risk that the dead center point of the operating mechanism will be passed, despite the fact that the mechanism is urged in the opposite direction by spring means for example of a spring return motor. This can involve significant disadvantages, since a flame front or explosive and/or poisonous combustion gases can thus penetrate past a fire damper of this design.

The purpose of the invention is therefore to achieve a simple and inexpensive locking device of the type described by way of introduction, which has a reliable locking function when the damper is in its closed position and which has a simple indication of the status of the lock/damper.

This is achieved by a device of the type described by way of introduction which has the features disclosed in the charac¬ terizing clause of the attached claim 1. A preferred embodi- ment of the locking device, and advantageous further deve¬ lopments and improvements, are disclosed in the dependent claims.

A locking device according to the invention provides a heat- resistant locking of the damper against opening forces acting directly against the damper plate. The design of the damper is such that the locking ceases when the damper is opened by the damper motor instead of by other external forces. In this way, the damper can always be opened and closed by the motor via remote control, e.g. to check the function.

The locking device according to the invention is described in more detail below with reference to the accompanying schema¬ tic drawing. Figure 1 shows the locking device in horizontal view,

Figure 2 is a view of the device in Figure 1 as seen from the side,

Figure 3 shows the locking device in Figure 1 in end view, and

Figure 4 shows a portion of the pivot arm of the locking device on a larger scale.

A motor shaft 1 actuates the damper plate (not shown) via the pivot arm 2 and a linkage system 3 connected therewith (shown partially here) . The pivot arm 2 is mounted on the motor shaft 1 in such a way that there is a "dead" angle of about +5 - -5 in the transmission of the rotational movement of the motor shaft 1 to swing the pivot arm 2. This "dead" angle is achieved by giving the motor shaft 1 a rectangular cross section 4 (see Fig 4) while the corresponding hole 5 in the pivot arm 2 is made with a double trapezoid shape.

The pivot arm 2 has at one end a notch 6 which can be engaged by an axially displaceable lock bolt 7 when the damper plate (not shown) is moved via the linkage system 3 to its closed position. The lock bolt 7 is mounted in a guide 8, which is a portion of the mounting plate 9. The lock bolt 7 is held in its extended position, i.e. in engagement with the notch 6 of the pivot arm 2, by means of the pressure exerted by a heli¬ cal spring 10. The lock bolt 7 can be forced out of engage- ment with the notch 6 of the pivot arm 2 with the aid of a rocker arm 11, mounted on the mounting plate 9. One end of said rocker arm acts on a flange 12 on the lock bolt 7. The other end of the rocker arm 11 is displaceable by means of a circle segment 13 mounted on the motor shaft 1. Said other end of the rocker arm 11 is also provided with a corner 14 facing said segment 13, which is bent up somewhat so that the rocker arm 11 is forced upwards onto the surface of the seg¬ ment 13 when the segment is rotated against the corner 14 by means of the shaft 1. By virtue of the fact that the end of the lock bolt 7 pro¬ trudes through the notch 6 in the pivot arm, on the front of the pivot arm 2, when the lock bolt 7 is in its locking posi¬ tion, a simple and reliable indication is provided of the current status of the damper locking device. A protruding lock bolt end indicates a damper which is locked. A retracted bolt end indicates that the damper is in its unlocked posi¬ tion. In order to improve the visibility of the indication, it is advisable to provide the end of the bolt with a signal colour, e.g. red, yellow, orange or possibly day glow**-^. It is also possible to transmit the indication, by means of a remote or contact sensor coupled to the end of the bolt, suitably via electrical signal lines, to a monitoring unit located remote from the locking device.

When the segment 13 is in the position shown in Figure 1, the other end of the rocker arm 11 is free of the segment 13, and the lock bolt 7 is able to lock the pivot arm 2 in the manner described above. In this position (closed damper) , any forces on the linkage system 3 cannot result in the damper opening.

When opening the damper with the aid of the motor, the lock¬ ing bolt is disengaged in the following manner: due to the "dead" angle between the motor shaft 1 and the pivot arm 2, the motor shaft can be rotated up to 10° without actuating the pivot arm 2 locked by the lock bolt 7. During this ini¬ tial rotation of the motor shaft 1, the segment 13, solidly fixed to the motor shaft, is rotated and will come into con¬ tact with the first end of the rocker arm 11 and force it upwards, so that the other end of the rocker arm 11 moves downwards and presses down the lock bolt 7 to a position out of engagement with the lock notch 6. The pivot arm 2 is then free to follow the motor shaft l during its continued rota¬ tional movement and finally positions the damper plate (not shown) via the linkage system 3 in its opened position.

It is also possible, within the scope of the invention, * to vary the operation of the lock bolt in several ways. For example, the lock bolt can be operated directly by the angle segment, which in that case has a turned-up edge and a circle arcuate groove, in which the lock bolt is guided. The upturned edge pushes the lock bolt out of its locked position when the segment is rotated.

Claims

1. Locking device for a fire-inhibiting shut-off damper which is opened by electromechanical or pneumatic drive means and which is closed by a spring device, rotation of the shaft (1) of the drive means being transmitted to a damper plate via a pivot arm (2), c h a r a c t e r i z e d in that the pivot arm (2) has a notch (6) for a spring-biased lock bolt (7) and is joined to the drive shaft (1) in such a manner that the shaft (1) , when the damper is in its closed position, can be rotated a predetermined angle before the pivot arm (2) is caused to rotate therewith, said initial rotation of the shaft (1) being utilized to displace the lock bolt (7) out of its position locking the pivot arm (2) .

2. Locking device according to Claim 1, c h a r a c t e r - i z e d in that the unlocking displacement of the lock bolt

(7) is achieved by a rocker arm (11) , which is actuated by a segment (13) mounted on the drive shaft (1) .

3. Locking device according to Claim 1 or 2, c h a r a c - t e r i z e d in that the axial displacement position of the lock bolt (7) provides an indication signal for the status of the damper.

4. Locking device according to Claim 3, c h a r a c t e r - i z e d in that the lock bolt has a protrudable end which is provided with a signal colour.

5. Locking device according to Claim 3, c h a r a c t e r ¬ i z e d in that the displacement position of the lock bolt is sensed by at least one sensor, which sends electrical impulses to a monitoring unit.