EP0699095B1

EP0699095B1 - Fire damper and a fire damper control system

Info

Publication number: EP0699095B1
Application number: EP94915738A
Authority: EP
Inventors: Ke Nerell; Ulf WIKSTRÖM
Original assignee: Nv Brandstopp AB
Current assignee: Nv Brandstopp AB
Priority date: 1993-05-12
Filing date: 1994-05-10
Publication date: 2000-06-28
Anticipated expiration: 2014-05-10
Also published as: WO1994026352A1; EP0699095A1; FI955432A; FI109877B; NO954522L; AU6763994A; NO954522D0; DE69425056D1; FI955432A0; DE69425056T2; DK0699095T3

Abstract

Device for rotating a shaft between a starting position and a working position, preferably a rotary shaft (6; 28) of a fire damper (4; 50). The shaft (6; 28) can be rotated between the starting position and the working position by simultaneous actuation of a rotary motor (7; 36) and an electromagnet (13; 38) against the biassing force of a return spring (17; 52). The motor has an output shaft driven by a gear train and provided with a pinion (8; 32) which is in engagement with a toothed segment (5; 30), which, together with the return spring (17; 52) is mounted on the shaft (6; 28). By actuating the electromagnet (13; 38) and the motor (7; 36), the spring can be tensioned via the pinion (8; 32) and the toothed segment (5; 30) at the same time as the shaft (6; 28) is rotated to its working position. By means of a microprocessor (20) it is possible to individually control a monitor, via a two-wired loop, each of a group of fire dampers.

Description

The present invention relates to a control system and method for preventing the spreading of fire and smoke in a ventilation system, comprising at least one damper unit being supplied with at least one damper device, which is manoeuvrable between a starting point and a working position and by which an interruption in the energy supply, which is unintentional or which is initiated via sensing means, causes an automatic return of the damper device to its starting point, and a central unit being provided for remote control and monitoring of said damper unit.
Such a system can be used for example to open and close a flap valve for preventing the spreading of fire and smoke.
Active fire protection can save human lifes in a catastrophic situation. Hitherto there has not been any really good method of protection against the dispersion of fire and smoke via narrow ventilation ducts. A smoke and fire damper according to the invention effectively stops combustion gases and smoke produced in a fire from spreading via the ventilation system of a building. The fire damper limits the damage and helps prevent catastrophes occurring in hotels, ships, industrial buildings, nursing homes, hospitals, office buildings, storage buildings and schools.
By connecting each fire damper to a new, completely computerized monitoring and control system in a two-wire configuration, which is designed to be used for monitoring the fire dampers with associated smoke detectors and thermoswitches, it is possible to automatically check the functioning of each fire damper, thus eliminating the necessity of extra fire insulation of the ventilation ducts. Each fire damper has built-in smoke detectors and thermoswitches and can, if there is to be central surveillance, be coupled to the monitoring and control system by means of a single twisted two-conductor cable.
US-A-4,928,583 discloses an air flow control system for controlling the air flow within a building having a blower for recirculating the air in the building comprising vents for venting air out of the building and means for closing the vents upon the detection of fire, smoke, or high heat in the building. The system also includes sensors for detecting fire, smoke, or high heat in the building. A breaker switch connected to the blower is also included in the system for disabling the blower to stop recirculation of the air upon the detection of fire, smoke, and high heat in the building.
JP-A-02299672 describes a disaster prevention system having a processing portion which decides whether or not each equipment operate. Upon malfunction image processing part and alarm producing portion are notified. Image processing part and a monitor display a visual alarm and a sound alarm to signal any malfunctioning.
Spring-loaded gear train motors for fire dampers are previously known in control technology, but these motors are often complicated in their design and are thus expensive to manufacture as well as being space-consuming, which means that in general they are only suitable for quite large installations. Due to the relatively large external dimensions of such a motor, it is as a rule not possible to mount it in direct connection with a flap valve for example in a duct section, which is often in turn located inside a dividing wall. The motor is instead mounted separate from the duct section on either side of the wall. In order to transmit the rotary motion of the motor to the damper, some type of transmission is required, e.g. a shaft with an angle transmission, a belt transmission or a linkage arm system.
The purpose of the present invention is therefore to provide, in a simpler and less expensive manner than previously, a control system comprising an operating device for fire dampers, which reliably blocks the damper in the closed position, which system is flexible and which is inexpensive to install and wire. This is achieved by an improved control system in which the damper unit is connectable to the central unit and at least one further damper unit as well, by means of at least one digital control circuit in the form of a loop. A corresponding method is characterized in that said central unit performs remote control and monitoring of each damper unit, which is, directly or via an adjacent damper unit, connected to the central unit by means of at least one digital control circuit in the form of a loop. Advantageous further developments and improvements of the invention are revealed in the dependent claims.
The device according to the invention is intended to be controlled by means of a modular, expandable central unit "DDC", which via two-wire connectors in three loops can be connected to up to 96 damper units for digital remote control and moni-toring of fire dampers coupled to each damper unit. Two fire dampers with associated sensing means, i.e. thermounit. It is thus possible with DDC to identify and control a total of 192 fire dampers with thermoswitches and smoke detectors. With DDC it is possible, via only one two-wire cable, to remotely monitor on a central display both the supply and exhaust ducts to each individual room, e.g. in a hotel or a nursing home. The display is suitably in the form of signal lamps which have different colours depending on what type of alarm is to be indicted (green, yellow, red etc, red preferably being used to indicate fire and smoke alarm).
It is possible to control the following functions from the central unit:
1) Service alarm is indicated when a smoke detector or a thermoswitch has reached a degree of contamination which could impede its functioning, i.e. replacement or cleaning is required).
2) Alarm due to the presence of smoke or overheating, which means that the fire damper in question is closed and blocked in its closed position.
3) Electrical failure in connection with a damper unit, which means that the dampers in question will be closed and blocked in their closed position.
4) Manual exercising of any selected damper at regular time intervals is controllable from the central unit. With a clock at the central unit it is possible to set the desired periodicity, e.g. a function check of each damper in the system once per 48 hours or in accordance with applicable building codes. During an alarm and during the automatic function check, the supply of current is broken to the fans in question.
To make the system flexible and at the same time keep the installation cost down, the communication between the dampers and the central unit is done digitally with a two-wire system. Each damper has a unique address and in this way the communication can be effected in two directions between the central unit and the damper. Communication is also possible with a superior computer, a telenet work etc. A printer can also be coupled directly to the central unit.
Embodiments of the invention will be described in more detail below only in the form of examples, with reference to the accompanying schematic drawings which show the invention applied to the operation of a rotational flap damper in a ventilation duct. The invention is, however, not limited to the operation of dampers but can also be used for other devices where a rotational movement with spring return is desirable.

Figure 1: shows the principle of one embodiment of the device partially in section, with the motor in driving connection with the damper, which is in its open position,
Figure 2: shows a device according to Figure 1 with the motor disengaged and with the damper in its closed position,
Figure 3: shows a side view of a preferred embodiment of a damper housing for the device,
Figure 4: shows a preferred embodiment of the device in side view,
Figure 5: shows the device according to Figure 4 in a horisontal view,
Figure 6: shows a wiring diagram for a group of devices according to the invention connected to a central unit.

In Figures 1 and 2, the letter A designates a ventilation duct with abutments 2 and 3 for a damper 4, which is joined to a gear 5 mounted on a rotary shaft 6 for the damper. Near the gear 5 there is mounted a gear train motor 7, which has at one end an output shaft and a pinion 8 mounted thereon. The gear train motor is pivotally mounted about a fixed pivot pin 9 disposed at the same end next to the pinion 8 in such a manner that the center axes of the pivot pin, the damper, the pinion and the gear 5 are all parallel to each other. On the pivot pin 9 there is also mounted a pawl 10 biassed by a leaf spring 11 towards the gear 5. The pawl 10 is also provided with a heel 12 directed against the gear train motor 7 and which, under the influence of the spring 11, strives to come into contact with the outside of the motor 7.
A linear motor in the form of an electromagnet 13 is pivotally mounted on an anchoring pin 14 and the linearly displaceable rod-spaced core of the magnet is joined at its free end to an operating pin 15 securely anchored to the other end of the motor 7. A spiral spring 16 is placed over the protruding portion of the magnetic core and bears with one end against the opposite end of the magnetic coil and bears with its other end against a stop on the protruding portion of the magnetic core. The spiral spring 16 thus strives to push the core out of the coil, when the coil is free of current.
A spiral spring 17 acting as a return spring and provided with long legs is mounted on the shaft 6. One leg is fixed at the point 18 while the other leg is in resilient contact with a spring pin 19 fixed to the gear 5.
The gear train motor 7 and the electromagnet 13 each have individual connecting wires (not shown) of conventional type, for connecting a driving voltage and an operating voltage. Connection and disconnection of these voltages is controlled by means of a control unit 20, e.g. a microprocessor with presettable command values, which obtain their control signals (the actual values) from sensors (not shown) in the duct A in question, suitably smoke detectors and temperature sensors or the like of a type which is known per se. Normally the operating voltage to the electromagnet 13 and the drive voltage to the gear train motor 7 are connected by the control unit 20. Since the electromagnet is thus activated by the operating voltage, the displaceable core is affected by the magnetic field so that it is displaced into the magnet against the force of the spiral spring 16, thus compressing the spring at the same time as the core, via the pivot connection with the operating pin 15, pulls the gear train motor 7 with it in its displacement. Since the motor 7 is pivotally mounted on the pin 9, the motor will be rotable about said pin until the pinion 8 engages the gear 5 on the shaft 6. Since the driving voltage of the gear train motor 7 is normally also turned on by the control unit 20, the output shaft of the motor, with the pinion 8 mounted thereon, will rotate in the direction of the arrow, and the gear 5 will rotate in the direction of the arrow M carrying with it the shaft 6 and the second leg of the return spring 17. This rotates the damper 4 to the opened position at the same time as the return spring 17 is tensioned. In certain cases, the rotary movement is limited by a limit switch (not shown here), which sends a signal to the control unit 20 corresponding to a predetermined angle of rotation of the shaft 6.
When one or more types of sensors signal abnormal values to the control unit, or if the control unit registers an unintended power failure, both the operating voltage and the driving voltage are shut off. The core of the electromagnet 13 is thus pushed out of the magnet under the influence of the pretensioned spiral spring 16, and the gear train motor 7 is pivoted about the pin 9 so that the pinion 8 is no longer in engagement with the gear 5 of the shaft 6. The return spring 17 then returns, via the spring pin 19, the gear 5 and the shaft 6, the damper 4 in the direction of the arrow M' to the starting position in sealing contact with the abutments 2 and 3. By virtue of the fact that the rotational position of the motor 7 is changed relative to the heel 12, it is disengaged and the pawl 10, by means of the bias of the leaf spring 11 is swung into engagement with a notch on the gear 5, blocking it against rotation in the opposite direction indicated by the arrow M. Only when the electromagnet 13 is reactivated will the pawl 10 be pivoted from its blocking position by the gear train motor 7 being rotated about the pin 9.
A preferred embodiment of the invention is illustrated in Figures 3-6 and comprises, in addition to the central control unit 20, two end panels 21,22, and a two-part housing 24 in the form of a duct, said housing being coupled into a unit by means of a flange coupling 26. On a damper shaft 28 arranged in the housing there is mounted a gear in the form of a toothed segment 30, which is in permanent engagement with the pinion 32 of a drive unit 31, said pinion being mounted on the output shaft of the drive unit 31 which can be fixedly mounted relative to the toothed segment 30. The pinion 32 of the output shaft is connected to an electric motor 36 of the drive unit 31 by means of a gear train 34. An electromagnet 38 can also be fixedly mounted relative to the toothed segment 30. The magnet moves, via a linkage arm 40, a blocking element 42 between a position blocking the toothed segment 30 and a position releasing the toothed segment. Two microswitches 44,46 are mounted on either side of the motor 36 and act as position sensors for the position of the damper shaft 28 and thus the position of the damper. The microswitches 44,46 are actuated by a pin 47 fixed to the toothed segment. The motor 36 is mounted on a motor plate 48 and is activated together with the electromagnet 38. The damper shaft 28 carries a damper plate 50, and a torsion spring 52 together with a spring guide 54 are mounted on the damper shaft 28, by means of which the damper plate 50 is continuously biassed towards the closed position.
When both the motor 36 and the electromagnet 38 are actuated, the blocking element 42 releases the toothed segment 30 and this permits the toothed segment to move, rotating the damper shaft 28 thus opening the damper and tensioning the torsion spring 52. As soon as the motor and the electromagnet 38 are deactivated, the tension energy in the spring 52 is released returning the damper to its closed position, where it is locked by the blocking means 42 being moved by a compression spring 56 to a position blocking the toothed segment 30. In this position, the damper cannot be opened unless the motor and the electromagnet are reactivated by supplying them with drive voltage.
In the damper housing 24 there is an insulation 58, preferably of mineral wool (Promatect type L). The damper housing 24 is coated on its interior with a fire-inhibiting paint from Casco Nobel in three layers, which has been cured and which constitutes significant heat-insulation. The paint designation is Hensoterm 4 KS, white matt, intended for fire insulation of supporting steel structures. The fire-inhibiting paint is also applied to the mounting 60 for the damper plate 50 shaft as above, which substantially extends the resistance to through-burning of the damper plate. The damper plate 50 itself is suitably made in three layers of a fire-resistant material of conventional type, and the surfaces of the damper itself are treated with fire-inhibiting paint as above. The damper plate 50 abuts against, in its closed position, sealing strips 62 (Z-strips) of fire-resistant foamed plastic arranged on the walls of the housing 24.
The drive unit 31 is made as a module which is easily replaceable if a fault for example should occur in the damper motor 36. It is important that the pinion 32 of the drive unit 31 be in correct engagement with the toothed segment 30, to assure reliable functioning of the device. The shaft of the pinion 32 is therefore provided with a ball bearing 64 mounted between the pinion 32 and the motor plate 48. An abutment 66 is made on the toothed segment 30, and serves as an abutment for the ball bearing 64 when a faulty drive unit has been removed and a new drive unit 31 is put in place by means of guide and anchoring rails (not shown). By suitably forming the abutment 66 and corresponding dimensioning of the ball bearing 64, correct play is always assured between the pinion 32 and the toothed segment 30, by only moving each drive unit 31 during assembly towards the toothed segment 30 until the ball bearing 64 is in contact with the abutment 66, whereupon the drive unit is screwed securely to the damper.
In order to make the damper more flexible and facilitate inspection of its inside when it is mounted in a wall, it is suitable to connect a T-pipe to the output endpiece, said T-pipe being connected to the ventilation duct in question with its end opposite to the endpiece and having an opening 90° relative to said ends, through which it is possible, with the aid of a mirror for example, to inspect the interior of the fire damper. This opening is rotatable 360° by rotating the entire T-pipe to the desired position, which facilitates access to the opening. During operation the opening is covered by an inspection lid in the center of which a smoke detector is suitably mounted.

Claims

Control system for preventing the spreading of fire and smoke in a ventilation system, comprising at least one damper unit (101,233,365) being supplied with at least one damper device (4,50), which is manoeuvrable between a starting point and a working position and by which an interruption in the energy supply, which is unintentional or which is initiated via sensing means, causes an automatic return of the damper device (4,50) to its starting point, and a central unit (20) being provided for remote control and monitoring of said damper unit (101,233, 365), characterised in that the damper unit is connectable to the central unit (20) and at least one further damper unit (102,234,366) as well, by means of at least one digital control circuit (100,200,300) in the form of a loop (101-132;233-264;365-396).
System according to claim 1, characterised in that the sensing means provided for each damper unit (101-396) comprise with the same interconnectable smoke detectors and thermo switches.
System according to claim 1 or 2, characterised in that a predetermined number of damper units (101-396) are connectable to the central unit (20).
System according to one of claims 1-3, characterised in that the central unit (20) is provided with a display having signal lamps, which have different colours depending on what type of alarm is to be indicated.
System according to one of claims 1-4, characterised in that the damper device is provided with at least one damper shaft (6;28), said shaft being moveable between a starting position and a working position corresponding to the starting point and the working position of the damper device (4,50), by means of cooperation between at least a first motor (7;36) and the biasing force of at least a first spring (17;52) and said shaft being lockable in the starting position by means of a blocking element (10;42).
System according to claim 5, characterised in that the shaft (6;28), upon an interruption in the energy supply, is lockable in the starting position by means of said blocking element in the form of a pawl or blocking arm (10;42), which is influenced by a second spring (16;56) and be re-released by means of a second motor (13;38) joined to said blocking arm or pawl.
System according to claim 6, characterised in that the first motor is a rotary motor (7;36) which has an output shaft with a drive pinion (8;32) which, at least when the second motor (13;38) is actuated, is in engagement with a rotary element (5;30) which is mounted on the shaft (6;28).
System according to claim 6 or 7, characterised in that the pawl or blocking arm (10;42) assumes its engagement position, blocking at least in one rotational direction of the shaft (6;28) when the actuation of the motors ceases, and that the pawl or blocking arm (10;42) can be moved by means of the second motor (13;38), between a position blocking the rotary element (5;30), in which the shaft (6;28) is held in its starting position, and a position releasing the rotary element (5;30).
System according to one of claims 6-8, characterised in that the first spring (17;52), which is mounted on the shaft (6;28) together with the rotary element (5;30) can be tensioned by simultaneous actuation of both the first (7;36) and the second (13;38) motor via the pinion (8,32) and the rotary element (5;30) at the same time as the shaft (6;28) can be rotated to its working position.
System according to one of claims 6-9, characterised in that the spring energy accumulated during the actuation of the motors (7;36,13;38) in the tensioned first spring (17;52) can be released via the rotary element (5;30) to the shaft (6;28) when the actuation of the motors ceases.
System according to one of claims 6-10, characterised in that the working position of the shaft (6;28) corresponds to a completely open position of a damper (50), non-rotatably joined to the shaft, while the starting position of the shaft (6;28) corresponds to the completely closed position of the damper, and that the damper in the closed position is in sealing contact with abutments (2,3;62) located on either side of the shaft.
System according to one of claims 6-11, characterised in that the first motor is a rotary motor (36) of a drive unit (31) which is fixedly mountable relative to the shaft (6;28) in such a manner that a ball bearing (64) arranged concentrically with the pinion (32) of the drive unit is moved into contact with an abutment (66) on the rotor element (30), which assures that there will always be a correct play between the motor pinion (32) and the rotor element (30) when the motor (36) is mounted in place.
System according to one of claims 6-11, characterised in that the rotary motor (7), which has an output shaft and a pinion (8), is pivotally mounted about a pin (9), that the rotational position of the rotary motor about the pin (9) depends on the actuation state of the second motor, and that the pinion (8) is thus pivotable to or from engagement with the rotary element (5).
System according to claim 13, characterised in that the pin (9) also constitutes the pivot pin for the pawl (10), which is moveable into or out of engagement with cavities located on the periphery of the rotary element (5), thus blocking rotation of said rotary element in at least a counter-direction to the arrow (M'), depending on the pivot position of the rotary motor (7) about the pin (9).
System according to one of claims 6-14, characterised in that each damper unit has a unique digital identification code, and that the first (7;36) and the second (13;38) motors are actuatable synchronously with each other depending on a digital control circuit which is coupled to a central unit for remote control and monitoring of each fire damper and its sensing means.
System according to one of claims 6-15, characterised in that the first spring (17;52) is a spiral spring and the second motor (13;38) is a linear motor, that the second spring (16;56) is a compression spring, that the drive wheel (8;32) is a pinion and that the rotary element (5;30) is a tooth segment.
System according to one of claims 3-16, characterised in that the number of damper units in each loop lies in an interval between one and thirty-two, and that two loops are provided.
System according to one of claims 3-16, characterised in that the number of damper units in each loop lies in an interval between one and thirty-two, and that three loops are provided.
System according to one of the preceding claims, characterised in that each damper unit has a unique address.
System according to claim 19, characterised in that communication can be effected in two directions between the central unit and each damper unit.
System according to claim 19, characterised in that the address is a digital identification code.
System according to one of the preceding claims, characterised in that the circuit comprises a two-wire loop.
System according to one of the preceding claims, characterised in that fire and smoke alarm is indicated by a red signal lamp.
Method for preventing the spreading of fire and smoke in a ventilation system by means of a system, comprising at least one damper unit (101, 233, 365) being supplied with at least one damper device (4, 50), which is manoeverable between a starting point and a working position by means of a central unit (20) and by which an interruption in the energy supply, which is unintentional or which is initiated via sensing means, causes an automatic return of the damper device (4, 50) to its starting point, characterised in that said central unit (20) performs remote control and monitoring of each damper unit (101, 233, 365), which is, directly or via an adjacent damper unit, connected to the central unit (20) by means of at least one digital control circuit (100, 200, 300) in the form of a loop (101-132;233-264;365-396).
Method according to claim 24, characterised in that service alarm is indicated of the control unit (20), on a display having signal lamps, when at least one sensing means has reached a predetermined degree of contamination.
Method according to claim 25, characterised in that fire and smoke alarm is indicated, by means of a red signal lamp on the display, due to the presence of smoke or over-heating, which means that the dampers in question will be closed and blocked in their closed positions.
Method according to one of claims 24-26, characterised in that an electrical failure in connection with a damper unit (101, 233, 365) will cause the dampers (4, 50) in question to be closed and blocked in their closed positions, which will be indicated on the display.
Method according to one of claims 24-27, characterised in that an individual function check of any selected damper (4, 50) is controllable from the central unit (20).
Method according to claim 28, characterised in that an automatic function check is performable at predetermined time intervals.
Method according to one of claims 24-29, characterised in that the supply of current is broken to the fans in question, by means of the central unit (20), during alarm and during the automatic function check.
Method according to one of claims 24-30, characterised in that communication can be effected in two directions between the central unit and a telenet work.
Method according to one of claims 24-30, characterised in that communication can be effected in two directions between the central unit and a superior computer.
System according to one of claims 1-23, characterised in that the central unit is a microprocessor (20).