Ventilation system for road tunnels

Abstract

A ventilation system (1) for road tunnels, which comprises at least one fan (90) and a power supply and actuation apparatus (10) which is connected to an electric power supply line (41) and supplies electric power to the fan (90), wherein the power supply and actuation apparatus (10) comprises an electronic control system configured to control the speed and the direction of rotation of the fan (90) and comprises an electrical conversion device (30) interposed between the power supply line (41) and the fan (90); and further comprising at least one temperature detection device; the power supply and actuation apparatus (10) comprises a motorized switching unit (20) which is configured to change, as a function of the temperature detected by the temperature detection device, the configuration of the power supply and actuation apparatus (10) from an ordinary configuration, in which the power supply and actuation apparatus (10) powers the fan (90) by means of the electrical conversion device (30), to an emergency configuration, in which the motorized switching unit (20) isolates the electrical conversion device (30), creating an electrical bypass so as to power the fan (90) directly from the electrical line (41), the electrical bypass being thermally isolated, and vice versa.

Description

[0001] The present invention relates to a ventilation system for road tunnels.

[0002] As is known, the presence of a ventilation system is of fundamental importance for the safety of a tunnel.

[0003] In particular, the main regulations and directives at national and European level on safety in road tunnels and motorway tunnels of a length greater than 1000 meters require the installation of "jet fan" or centralized ventilation systems, based on the results of risk analysis.

[0004] The choice and the dimensioning of the ventilation system must take into consideration the statistics for possible accidents that can cause fires and spills of toxic, harmful and inflammable substances. It must contribute to ensuring the level of safety set by the application of the risk analysis methodology and it must result in the definition of optimal plant engineering that is capable of ensuring: the dilution of vehicle emissions inside the tunnel under operating conditions (sanitary ventilation); the environmental compatibility of the structure; the management and control of smoke in the event of possible accidents identified as major (emergency ventilation).

[0005] Currently the fans produced internationally are usually constituted by the following elements: fan housing made of galvanized or stainless sheet steel; symmetrically- or asymmetrically-bladed impeller made of aluminum alloy or stainless steel; electric motor with supporting base; rigid suspension system; safety system; horizontal level sensor; vibration sensor; direct power supply or power supply through soft starter.

[0006] Furthermore, ventilation systems for tunnels comprise speed variators which must be installed in the vicinity of the fans.

[0007] If it is not possible to install speed variators in the vicinity of the fans, then the cross-section of the power supply cable of the motor placed between the variator and the terminals of the motor itself must be screened, unless otherwise indicated by the manufacturer of the inverter.

[0008] In particular, as also prescribed by the regulations, the level of the characteristics of resistance and reaction to fire of the components of all the plants and systems of the tunnel must take account of their structuring and degree of exposure to fire and of technological possibilities, and it must make it possible to maintain the necessary safety functions in the event of fire.

[0009] Practical tests have shown, for conventional fans, correct operation under steady-speed conditions in the presence of temperatures higher than 400°C. However, under variable-speed conditions with the use of speed variators, it has been found that after a limited number of sequences of starting and inverting the direction of rotation, the system is affected by resonance frequencies which lead to brittle fracture if the impeller is made of aluminum with consequent increase of the vibrations inside the fan.

[0010] Furthermore it is also desirable for the speed variators to ensure an operating temperature higher than 400°C.

[0011] It is in fact of little use to adopt fire-resistant cables, electricity generators and redundant power supplies, when the critical safety element goes out of service at 55-60°C.

[0012] The aim of the present invention is to provide a ventilation system for road tunnels that is capable of solving the above mentioned problems and overcoming the above mentioned limitations of the background art.

[0013] Within this aim, an object of the present invention is to provide a ventilation system for road tunnels that is capable of ensuring greater reliability in the event of fire.

[0014] Another object of the invention consists of providing a ventilation system for road tunnels that is capable of reducing consumption and the absorbed power.

[0015] Another object of the invention consists of providing a ventilation system for road tunnels that is easy to implement and economically competitive.

[0016] This aim and these and other objects which will become more apparent hereinafter are achieved by a ventilation system for road tunnels according to claim 1.

[0017] Further characteristics and advantages of the invention will become more apparent from the detailed description of a preferred, but not exclusive, embodiment of a ventilation system for road tunnels, illustrated by way of non-limiting example with the aid of the accompanying drawings wherein: Figure 1 is an electrical diagram of part of the ventilation system according to the invention; Figures 2, 3 and 4 are, respectively, a front elevation view and two side views of a possible embodiment of the power supply and actuation apparatus of the ventilation system.

[0018] With reference to the figures, the ventilation system for road tunnels, generally designated by the reference numeral 1, comprises at least one fan 90 which is adapted to be arranged, in a known manner, inside the tunnel.

[0019] The fan 90 is a fan adapted for the ventilation of road tunnels and comprises, in a known manner, at least one symmetrically- or asymmetrically-bladed impeller (preferably made of stainless steel) and an electric motor that rotates the impeller.

[0020] Normally the fan 90 also comprises: a fan housing made of stainless sheet steel, a supporting base for the motor, a rigid suspension system, a horizontal level sensor, and a vibration sensor.

[0021] The ventilation system 1 also comprises a power supply and actuation apparatus 10 which electrically powers the fan 90, and this power supply and actuation apparatus 10 is connected to an electric power supply line 41.

[0022] This power supply and actuation apparatus 10 comprises an electronic control system which is configured to control the speed and the direction of rotation of the fan 90.

[0023] This electronic control system in turn comprises an electrical conversion device 30 (such as an inverter) and optionally also an electric switching unit 31, interposed between the power supply line 41 and the fan 90.

[0024] In the preferred embodiments, the electrical conversion device 30 varies the frequency and / or the amplitude of the electric current in order to actuate and vary the speed of the fan 90.

[0025] According to the invention, the ventilation system 1 comprises at least one temperature detection device which is positioned in the power supply and actuation apparatus 10 and / or in, or proximately to, the fan 90.

[0026] Furthermore, according to the invention, the power supply and actuation apparatus 10 comprises a motorized switching unit 20 which is configured to modify, as a function of the temperature detected by the above mentioned temperature detection device, the configuration of the power supply and actuation apparatus 10 from an ordinary configuration to an emergency configuration, and vice versa.

[0027] In the ordinary configuration the power supply and actuation apparatus 10 powers the fan 90 by means of the electrical conversion device 30 (inverter).

[0028] In an emergency configuration the motorized switching unit 20 isolates the electrical conversion device 30, creating (inside the motorized switching unit 20 itself) an electrical bypass so as to supply power directly to the fan 90 from the electrical line 41. The electrical bypass is thermally isolated so as to withstand temperatures higher than 400°C for at least two hours.

[0029] Figure 1 shows the diagram of the power section of the preferred embodiment of the power supply and actuation apparatus 10.

[0030] Preferably, the motorized switching unit 20 is contained inside a textile protection made of mineral wool, or the motorized switching unit 20 itself is configured (using conventional techniques) to withstand a temperature of 400°C for at least two hours.

[0031] Therefore the bypass can operate under load at the rated current, at a temperature of 400°C and for a minimum length of time of 2 hours.

[0032] The motorized switching unit 20 further makes it possible to actuate the fan 90 in both directions of rotation.

[0033] Preferably, the power supply and actuation apparatus 10 is accommodated inside a box-like body 11 made of sheet metal 11 (preferably stainless steel) provided with a thermal insulation layer (inside the sheet metal).

[0034] In a particular preferred embodiment, the box-like body of sheet metal 11 is a stainless steel structure and its dimensions are 800mm x 1400mm x 450mm, but the dimensions can vary depending on the power installed and / or on the dimensions of the elements installed inside.

[0035] Preferably, there is a temperature detection device which is positioned proximately to the fan 90 in order to detect the temperature proximate to such fan 90 and which is functionally connected to the electronic control system, so that if the temperature at which the fan 90 operates exceeds a threshold value (for example 55-60°C) the electronic control system induces, by way of the motorized switching unit 20, the switchover to the emergency configuration.

[0036] In this case an emergency command is sent remotely to the power supply and actuation apparatus 10, and the latter, by means of the motorized switching unit 20, performs the switchover from ordinary configuration (actuation by inverter) to emergency configuration (bypass). The emergency command is also associated with a command governing the direction of rotation of the fan 90.

[0037] In the preferred embodiment, the power supply and actuation apparatus 10 also comprises a thermostat, which comprises a respective temperature detection device inside the box-like body 11, which is configured to actuate the motorized switching unit 20 in order to provide the emergency configuration when the detected temperature is equal to or higher than a threshold temperature (preferably 55-60°C). In this case the direction of rotation of the impeller of the fan 90 will be the direction in which the fan was rotating during the last start.

[0038] In more detail, the motorized switching unit 20 comprises a motor 21 and a series of switches 23 actuated by the motor 21.

[0039] Figures 2, 3 and 4 show an example of a box-like body 11 containing the power supply and actuation apparatus 10. The latter comprises conventional interface elements 18, 19 (switches, button panel for controlling the electronic control system, etc.) and aeration grilles 12.

[0040] With reference now to a particular preferred embodiment, the power supply and actuation apparatus 10 is adapted to be connected to a network (MODBUS protocol) for remote control and transmission of information (current, voltage, direction of rotation, hours of operation power factor, energy consumption, vibrations).

[0041] The box-like body 11 has a housing made of stainless steel with an IP55 protection rating, and is resistant to the action of chemical agents, to shocks and to vibrations, with switch and circuit breaker.

[0042] Also in this preferred embodiment, the power supply and actuation apparatus 10 has the following characteristics: input voltage level (V in): 380 - 480V ±10% / 600 - 690V ±10%; input frequency: 48-63 Hz; output frequency: 0-320 Hz; frequency resolution: 0.01 Hz; operating temperature: -10 to 50°C; storage temperature: -40 to 70°C.

[0043] Furthermore it comprises a harmonics filter LCL TDH <5% and a circuit breaker with a mechanical impediment that can be padlocked and withstand a temperature of 400°C for 2 hours.

[0044] Preferably, the power supply and actuation apparatus 10 also comprises analog and / or digital inputs for carrying out the monitoring of the fan (using a temperature sensor, vibration sensor, horizontal level sensor etc.).

[0045] The ventilation system 1 for road tunnels can comprise a plurality of fans 90, positioned at various zones of the tunnel, each one provided with a respective power supply and actuation apparatus 10.

[0046] The operation of the ventilation system 1 is described below.

[0047] Under normal conditions the fans 90 located inside the tunnel can all start together with the speed variators in order to eliminate the gases under normal conditions of transit or when vehicles are stopped owing to an accident that does not result in fire.

[0048] The electronic control system of the power supply and actuation apparatus 10 regulates the rotation speed of the fan 90 in terms of number of rpm and in the most suitable direction of flow, based on the environmental conditions.

[0049] In the presence of fire, with the fans 90 operating, the fans will be regulated as a function of the location and characteristics of the fire.

[0050] The fans located at the point where the fire is located will operate under normal conditions up to a threshold temperature (for example 55-60°C), detected by the detection device temperature, after which, by way of the motorized switching unit 20, the switchover to the emergency configuration (direct operation) will be effected, operating under these conditions up to 400°C for a maximum length of time of two hours.

[0051] In the event of a fire when the fans are stopped, the fans 90 that are located outside the zone where the fire is located are started in the ordinary configuration, and the fans that are located in the zone of the fire and / or with a temperature higher than 55-60°C are started in the emergency configuration, as they can operate under these conditions at up to 400°C for two hours.

[0052] In advanced embodiments in which there are a plurality of fans 90, such fans are controlled by a central system control unit which, by way of programs that receive information from pressure sensors, temperature sensors, environmental pollution sensors, or other physical, chemical or environmental parameters, located inside the tunnel and which, through a bus connection provided with fire-resistant cables or optic fibers, after analyzing all the parameters, set the speed and correct directions for operation under optimal conditions from the point of view of safety and the energy consumption, for example as described above.

[0053] This control unit in practice comprises a programmable electronic apparatus and is functionally connected to the power supply and actuation apparatuses 10 of each fan 90 so as to control them.

[0054] In practice it has been found that the ventilation system for road tunnels according to the present invention achieves the intended aim and objects in that it is capable of ensuring greater reliability in the event of fire.

[0055] Another advantage of the ventilation system for road tunnels, according to the invention, consists in that it reduces consumption and the absorbed power and also the noise levels.

[0056] Another advantage of the ventilation system for road tunnels, according to the invention, consists in that it is easy to implement and economically competitive.

[0057] Another advantage of the ventilation system for road tunnels, according to the invention, consists in that it ensures permanent control of the air flow.

[0058] The ventilation system for road tunnels thus conceived is susceptible of numerous modifications and variations all of which are within the scope of the appended claims.

[0059] Moreover, all the details may be substituted by other, technically equivalent elements.

[0060] In practice the materials employed, and the contingent dimensions and shapes, may be any according to requirements and to the state of the art.

[0061] Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs

Claims

1. A ventilation system (1) for road tunnels, which comprises at least one fan (90) and a power supply and actuation apparatus (10) which is connected to an electric power supply line (41) and supplies electric power to the fan (90); wherein said power supply and actuation apparatus (10) comprises an electronic control system configured to control the speed and the direction of rotation of the fan (90) and comprises an electrical conversion device (30) interposed between the power supply line (4) and the fan (90); wherein the system further comprises at least one temperature detection device, and wherein said power supply and actuation apparatus (10) comprises a motorized switching unit (20) which is configured to modify, as a function of the temperature detected by said temperature detection device, the configuration of said power supply and actuation apparatus (10): from an ordinary configuration, in which said power supply and actuation apparatus (10) supplies power to the fan (90) by means of said electrical conversion device (30), to an emergency configuration, in which said motorized switching unit (20) isolates said electrical conversion device (30), creating an electrical bypass so as to supply power directly to the fan (90) from said electrical line (41), and from an emergency configuration to an ordinary configuration, characterized in that said power supply and actuation apparatus (10) comprises also a thermostat which is configured to actuate said motorized switching unit (20) in order to provide said emergency configuration when the thermostat detected temperature is equal to or greater than a predetermined threshold temperature.

2. The ventilation system (1) according to claim 1, characterized in that said motorized switching unit (20) is contained inside a textile protection made of mineral wool.

3. The ventilation system (1) according to one or more of the preceding claims, characterized in that said power supply and actuation apparatus (10) is accommodated inside a box-like body made of sheet metal (11) provided with a thermal insulation layer.

4. The ventilation system (1) according to one or more of the preceding claims, characterized in that it comprises a temperature detection device which is located proximate to the fan (90) in order to detect the temperature proximate to said fan and which is functionally connected to said electronic control system.

5. The ventilation system (1) according to one or more of the preceding claims, characterized in that said motorized switching unit (20) comprises a motor (21) and a series of switches (23) actuated by said motor (21).

6. The ventilation system (1) according to one or more of the preceding claims, characterized in that it comprises a plurality of fans (90), each one powered and actuated by a respective power supply and actuation apparatus (10), and a central system control unit which comprises a programmable electronic apparatus and which is functionally connected to the power supply and actuation apparatuses (10) of each fan (90) so as to control them as a function of physical, chemical or environmental parameters detected by one or more sensors which are adapted to be arranged in the tunnel.

Images