SYSTEM AND METHOD FOR EXTRACTION OF SMOKE FROM ROAD TUNNELS

Technical Field: The present invention relates to a module, a system and a method for extraction of smoke from tunnels, in particular smoke developing inside long road tunnels due to motoring accidents.

Background and prior art:

Accidents in tunnels are more dangerous than in the open air. An explosion or fire may cause considerable damage, and hazardous substances cannot be removed quickly. Smoke causes poor visibility, lack of oxygen rapidly occurs and there may be panic. The below table from the handbook of tunnel fire safety of 2005 (Alan Beard & Richard Carrel) lists some of the tunnel fatalities in recent years, hence providing an insight into the tragic consequences of tunnel fire.

As a result, the serious hazards related to smoke development in road tunnels have been an issue of debates for decades, and numerous solutions have been proposed trying to reduce the consequences in case of smoke inducing accidents. Examples may be found in publications DE 3117147 Al, DE 19825420 Al , DE 102004027761 Al, EP 1544408 Al, EP 1398461 , KR 101088341 B, DE 102007040237 Al , US 4361079 and DE 7524273 U all disclose solutions where tunnels have been equipped with a closed extraction channel or duct connected to one or more ventilation means. As explained in DE 3117146 Al enables use of smoke sensors situated along the tunnel guidance of smoke from the source of the smoke into a nearby clo sable hole of the extraction duct. The extracted smoke may be conveyed to the outside either vertically or longitudinally.

However, there are still many tunnels worldwide that have no or insufficient systems for smoke extractions, some of these being of considerable length, for example over 1000 meters. To install a solution based on the prior art solutions mentioned above, i.e. to install a dedicated extraction duct having closable openings, often requires a considerable amount of cost and manpower.

It is thus an object of the present invention to provide an assembly that enables effective smoke extraction at or near the smoke source and which may be installed into existing and new tunnels in an easier and more cost favourable manner.

Summary of the invention:

The present invention is set forth and characterized in the main claims, while the dependent claims describe other characteristics of the invention.

In particular, the invention concerns a smoke extraction module smoke extraction module, a smoke extraction system and a method for using such a system which enables extracting of smoke from tunnels, in particular large road tunnels. The module comprises a duct for transportation of smoke, a suspension means which is at least indirectly connected to the duct, thereby enabling suspended connection between the duct and the tunnel wall or tunnel ceiling and a detachment mechanism, which, when activated, is arranged to detach the duct from the suspension means such that a displacement of the duct is enabled. The displacement of the duct is preferably a pure longitudinal displacement. Hereinafter a tunnel shall be interpreted as comprising any cavities where a fire outbreak is considered to represent a danger for life and health for living objects and/or considered to represent a risk of causing serious material damages. Examples are road tunnels, train tunnels, mines, etc.

In a preferred embodiment the duct remains suspended to the tunnel wall or tunnel ceiling after detachment. In another preferred embodiment the detachment mechanism comprises an activator such as a relay configured to receive signals from a smoke detector situated inside the tunnel and configured to actuate the detachment of the duct by for example the activation of one or more coils. In another preferred embodiment the detachment mechanism further comprises a smoke detector for detection of smoke inside the tunnel. In an alternative embodiment the smoke detector is a remote smoke detector transmitting signals to the receiver. In another preferred embodiment the detachment mechanism further comprises fastening means such as a locking bolt, while the module also comprises one or more retaining means. The suspension means and the retaining means may advantageously be releasably interconnected by the fastening means. Furthermore, the suspension means and the retaining means may be pivotably interconnected, for example by the use of a hinge.

In another preferred embodiment the detachment mechanism comprising an activator configured to receive signals from a smoke detector situated inside the tunnel as well as one or more elongated objects such as a rod, a wire, a cable or similar, extending between the fastening means and the activator.

In another preferred embodiment the suspension means comprises one or more first hangers while the retaining means comprises one or more second hangers, wherein the first and second hangers are attached to the tunnel wall or ceiling during use. In this embodiment the second hanger may be attached to the module such that the duct remains suspended in the tunnel wall or ceiling after detachment. The attachment may be directly on the duct itself or on the retaining means

The invention also concerns a smoke extraction system for extracting smoke from tunnels. The system comprises a plurality of smoke extraction modules in accordance with the features disclosed above which are mutually arranged in an end-to-end fashion to form a channel extending along the tunnel during use. The system also comprises an evacuation system arranged at one or both longitudinal ends of the channel for extraction of smoke.

In a preferred embodiment the displacement of the duct within the system causes a longitudinal misalignment relative to adjacent ducts.

In addition to the module and the system mentioned above the invention also concerns a method for displacing a smoke extraction module arranged within a smoke extraction system comprising a plurality of modules arranged in an end-to- end fashion to form a channel extending along the tunnel, where each module comprises a duct for transportation of smoke and a suspension means suspending the duct from the tunnel wall. The method comprises the following steps:

a) detecting a level of smoke exceeding a predetermined level by means of a smoke detector and

b) actuating a detachment mechanism detaching the duct from the suspension means , thereby causing a longitudinal misalignment of the duct relative to adjacent ducts. In a preferred embodiment the method also comprises the step of transmitting signals from the smoke detector to an activator between step a) and step b), where said activator is configured to actuate the displacement mechanism. All method steps may advantageously be controlled by the use of a common control unit.

Brief description of the draw ings:

Fig. 1 is a perspective view of a tunnel situated smoke extraction system in accordance with the invention,

Fig. 2 is a more detailed view of the smoke extraction system of fig. 1 where a fire situation has occurred beneath a smoke extraction module in accordance with the invention,

Fig. 3 is a view of the smoke extraction system of fig. 2 after successful detachment from adjacent modules,

Fig. 4 is a perspective view of the smoke extraction system of fig. 1 after successful detachment of the module from the adjacent modules,

Fig. 5 is a perspective view of a smoke extraction module in accordance with a first embodiment of the invention, prior to detachment,

Figs. 6 (a) and (b) are detailed views of a detachment mechanism arranged on a smoke extraction module in accordance with a first embodiment of the invention, wherein fig. 6 (a) and fig. 6 (b) shows the detachment mechanism before and immediately after detachment, respectively,

Fig. 7 is a view of the smoke extraction module of fig. 4 after completion of a successful detachment,

Fig. 8 is a perspective view of a smoke extraction system in accordance with the invention, including a smoke extraction unit arranged at each longitudinal end of assembly of modules,

Fig. 9 is a perspective view of a smoke extraction module in accordance with a second embodiment of the invention, prior to detachment

Fig. 10 is a view of the smoke extraction module of fig. 9 showing the opposite radial side of the module,

Fig. 11 is a detailed view of a part of a detachment mechanism arranged on a smoke extraction module in accordance with a second embodiment of the invention, prior to detachment,

Figs. 12 (a) and (b) are detailed views of another part of a detachment mechanism arranged on a smoke extraction module in accordance with a second embodiment of the invention, wherein fig. 12 (a) and (b) shows the interior components with and without a detachment activating coil, respectively,

Fig. 13 is a detailed view of the detachment mechanism arranged on a smoke extraction module in accordance with a second embodiment of the invention, immediately after detachment and

Fig. 14 is a perspective view of the smoke extraction module of fig. 9 after completion of a successful detachment.

Detailed description of the invention

Figure 1 shows the inventive smoke extraction system 20 arranged within a road tunnel prior to implementation of any smoke extraction procedure. An extraction unit 21 in form of a vacuum pump is arranged at a longitudinal side of a smoke guiding channel, which channel is composed of a plurality of smoke extraction modules Ι ,Γ with ducts 2,2' arranged in an end-to-end fashion along the entire road tunnel. The pumping capacity of the vacuum pump 21 should be equal or higher than the pumping capacity required to extract smoke from anywhere in the road tunnel to either or both channel ends during at least one fire outbreak. The minimum required pumping capacity will of course vary depending on parameters such as length of road tunnel, mean diameter of smoke guiding channel, number of modules 1 within the channel, etc. A more detailed view of the smoke extraction system 20 is seen in figure 2, where a single fire outbreak has started in a van located immediately beneath a particular module 1, hereinafter defined as the fire module 1. As is apparent from the figure, ducts 2' belonging to adjacent modules Γ are in normal operation arranged in gas flowing connection with the duct 2 of the fire module 1 , that is on each of its longitudinal sides. In order to automatically detect and determine the position(s) of any fire outbreak a plurality of smoke detectors 9 are arranged at specific locations within the tunnel, preferably in regular intervals along the entire tunnel length. In the particular embodiment of figure 2 the smoke detectors 9 are fixed onto the tunnel wall 4, i.e. remote from the ducts 2,2'. However, they may alternatively (or additionally) be fastened to the channel itself. Figures 3 and 4 show similar views of the smoke extraction system 20 as in figures 1 and 2, respectively, where the fire module 1 have been detached from the remaining part of the smoke guiding channel, thereby creating two open channels which extends from the end of the adjacent modules 1 ' situated closest to the position of the fire outbreak to the corresponding vacuum pump 21 ,21 ' . The double arrows 30 indicate the direction of the smoke 6 during pumping.

Details of two different detachment mechanisms 5 detaching the fire module 1 from the adjacent modules 1 ' will now be described.

Figure 5 shows a first embodiment of the inventive module 1 where a stable suspension of the module 1 is ensured by the attachment of two hangers 14, each being at one end fixed to the tunnel roof / wall 4 and the other end to duct enclosing locking collars 10,1 1 arranged near the longitudinal ends of the duct 2. Further, each locking collar 10, 1 1 comprises an upper collar 10, a lower collar 1 1 and a detachment mechanism 5 (indicated within a dotted square in figure 5), where the detachment mechanism provides releasable connection between at least one of the two facing end pairs belonging to the upper and lower collars 10,1 1 during normal / suspended position. The detachment mechanism 5 comprises an activation device 7 arranged inside a cover 28 at the upper collar 10 and a bolt 8 (or any other releasable fastening means) interconnecting the two collars 10,1 1 at their ends. As better illustrated in figures 6 (a) and (b) the facing ends of the upper and lower collars 10,1 1 includes radial protrusions 18,18' with holes 32,33, where at least the upper hole 32 belonging to the upper protrusion 18 has an inner diameter being larger than the outer diameter of the bolts head 8". The stem 8- of the bolt 8 is fixed to the lower protrusion 18' by known means (threads, nuts, etc). When the bolt 8 is fixed to the lower protrusion 18' and extends through the upper hole 32 (figure 6 (a)), an end piece 27 in the form of a fork is arranged to partly enclose the stem 8' of the bolt 8 immediately below the bolt head 8", thereby fixing the bolt 8 also to the upper collar 10. The end piece 27 remains in this locked position by means of a voltage controlled locking relay 34 pressing a spring (not shown) towards the stem 8' of the bolt 8 in absence of any applied voltage. Figure 6 (b) illustrates the situation when the locking relay 34 has been activated by the application of a specific voltage (or any other activation requirements for the specific locking relay). The end piece 27 is retracted due to reduced pressure on the spring set up by a coil in the relay, and the bolt head 8' is dragged through the upper hole 32 by the gravitational force. The upper and lower collars 10,1 1 are hence detached, and the duct 2 of the fire module 1 obtains the desired longitudinal misalignment relative to the ducts 2' of the adjacent modules Γ enabling the commence of smoke extraction. The double arrows 35 in figures 6 (a) and 6 (b) indicate the force direction of end piece 27 without and with applied voltage on the locking relay 34, respectively. Figure 7 shows the equilibrium position after a completed detachment of in total four detachment mechanisms 5, i.e. one detachment mechanism 5 for each end pairs of the upper and lower collars 10,1 1. In this embodiment two hangers 14,15 per longitudinal duct end are used, the first and second hanger 14,15 being fixed to the upper and lower collar 10,1 1 , respectively. Figure 8 shows an illustration of the smoke extraction system 20 comprising

- a smoke guiding channel composed of five modules 1,1 ',

- vacuum pump 21 ,21 ' arranged at each end of the channel to pump out smoke 6,

- a detachment mechanism 5 fixed at both ends of each module 1 ,1 ' to selectively displace one or more corresponding ducts 2,2',

- smoke detectors 9 arranged along the entire length of the channel and - a control unit 35 controlling the operation parameters of the vacuum pumps 21 ,21 ' , the transmission signals of the smoke detectors 9 and the activation of the locking relays 34 situated within the detachment mechanisms 5.

With the particular setup any module 1 may be detached from the adjacent modules 1 ' . For example, if the smoke detectors 9 labeled ii and iv detect smoke 6 indicating one or more fire outbreaks, signals will be sent initiating the activation of the one or more detachment mechanisms 5 connected to the modules 2' situated immediately above the activated smoke detector(s) 9. Hence, in figure 8 only the ducts directly connected to the vacuum pumps 21 ,21 ' and the central module 2 will remain in their original positions. In practice, the number of modules in a road tunnel will be significantly larger.

Figure 9 shows a second embodiment of the inventive smoke extraction module 1 ,1 ' prior to detachment. As for the first embodiment (figure 5) a stable suspension of the module 1 is ensured by the attachment of two hangers 14 being at one end fixed to the tunnel roof / wall 4 and the other end to enclosing locking collars 10,1 1 arranged near the longitudinal ends of the duct 2. Each locking collar 10,1 1 further comprises an upper collar 10, a lower collar 1 1 and a bolt 8 (or any other releasable fastening means) interconnecting the two collars 10,1 1 at their ends. The facing ends of the upper and lower collars 10,1 1 includes upper and lower radial protrusions 18,18' with holes 32,33, where both holes 32,33 have an inner diameter being larger than the outer diameter of the stem 8' of the bolt 8 but smaller than the outer diameter of the bolt head 8". The lower part of the stem 8' displays a radial hole. After arranging the bolt 8 through both holes 32,33 of the radial protrusions 18,18' so that the bolt head 8" rests on the upper radial protrusion 18, a suitable cotter pin 17 is inserted, thereby locking the ends of the two collars 10,1 1. An identical arrangement may be made at the opposite radial side of the duct 2. However, in a preferred embodiment (figure 10) the upper and lower collars 10, 1 1 are at this side interconnected by pivotable hinges 16. In contrast to the first embodiment, the activation of the detachment procedure is achieved by a common activation mechanism 7 situated at a distance from the bolts 8. A cable or rod 12 extends from each of the cotter pins 17 to the activation mechanism 7, as detailed in figure 1 1. Figures 12 (a) and (b) show the innards of the activation mechanism 7, where the ends of the cables / rods 12 are connected to a common voltage controlled coil 24 (figure 12 (a)), the latter enabling a pulling force on the cables 12 in direction towards each other thereby pulling the cables 12 a distance that is sufficient to pull out the respective cotter pins 17. Similarly to the first embodiment the cotter pins 17 remain in place and therefore locks the two collars 10,1 1 in absence of any applied voltage on the coil 24. Figure 12 (b) shows the activation mechanism 7 with the coil 24 removed. A relay 13 is seen arranged beneath the coil 24 which is electrically connected to the coil 24 and a smoke detector 9, the latter via electrical wires 23. Hence, when the smoke detector 9 detects smoke 6 above a predefined smoke density, a signal transmitted through the wires 23 activates the relay 13, which again applies the necessary voltage on the coil 24 in order to pull the cotter pins 17 out of the bolts 8 (figure 13). Figure 14 shows the equilibrium position after a completed detachment of in total two detachment mechanisms 5, i.e. one detachment mechanism 5 for one of two end pairs of the upper and lower collars 10, 1 1. Also in this embodiment two hangers 14,15 per longitudinal duct end are used, the first and second hanger 14,15 being fixed to the upper and lower collar 10,1 1, respectively.

In the preceding description, various aspects of the module, system and method according to the invention have been described with reference to the illustrative embodiment. For purposes of explanation, specific numbers, systems and configurations were set forth in order to provide a thorough understanding of the apparatus and its workings. However, this description is not intended to be construed in a limiting sense. Various modifications and variations of the illustrative embodiment, as well as other embodiments of the apparatus, which are apparent to persons skilled in the art to which the disclosed subject matter pertains, are deemed to lie within the scope of the present invention.