Patent Description:
As is known, the presence of a ventilation system is of fundamental importance for the safety of a tunnel.

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 <NUM> meters require the installation of "jet fan" or centralized ventilation systems, based on the results of risk analysis.

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:.

Currently the fans produced internationally are usually constituted by the following elements:.

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

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.

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.

Practical tests have shown, for conventional fans, correct operation under steady-speed conditions in the presence of temperatures higher than <NUM>. 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.

Furthermore it is also desirable for the speed variators to ensure an operating temperature higher than <NUM>.

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 <NUM>-<NUM>.

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.

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.

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

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

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 <NUM>.

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:.

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

The fan <NUM> 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.

Normally the fan <NUM> 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.

The ventilation system <NUM> also comprises a power supply and actuation apparatus <NUM> which electrically powers the fan <NUM>, and this power supply and actuation apparatus <NUM> is connected to an electric power supply line <NUM>.

This power supply and actuation apparatus <NUM> comprises an electronic control system which is configured to control the speed and the direction of rotation of the fan <NUM>.

This electronic control system in turn comprises an electrical conversion device <NUM> (such as an inverter) and optionally also an electric switching unit <NUM>, interposed between the power supply line <NUM> and the fan <NUM>.

In the preferred embodiments, the electrical conversion device <NUM> varies the frequency and/or the amplitude of the electric current in order to actuate and vary the speed of the fan <NUM>.

According to the invention, the ventilation system <NUM> comprises at least one temperature detection device which is positioned in the power supply and actuation apparatus <NUM> and/or in, or proximately to, the fan <NUM>.

Furthermore, according to the invention, the power supply and actuation apparatus <NUM> comprises a motorized switching unit <NUM> 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 <NUM> from an ordinary configuration to an emergency configuration, and vice versa.

In the ordinary configuration the power supply and actuation apparatus <NUM> powers the fan <NUM> by means of the electrical conversion device <NUM> (inverter).

In an emergency configuration the motorized switching unit <NUM> isolates the electrical conversion device <NUM>, creating (inside the motorized switching unit <NUM> itself) an electrical bypass so as to supply power directly to the fan <NUM> from the electrical line <NUM>. The electrical bypass is thermally isolated so as to withstand temperatures higher than <NUM> for at least two hours.

<FIG> shows the diagram of the power section of the preferred embodiment of the power supply and actuation apparatus <NUM>.

Preferably, the motorized switching unit <NUM> is contained inside a textile protection made of mineral wool, or the motorized switching unit <NUM> itself is configured (using conventional techniques) to withstand a temperature of <NUM> for at least two hours.

Therefore the bypass can operate under load at the rated current, at a temperature of <NUM> and for a minimum length of time of <NUM> hours.

The motorized switching unit <NUM> further makes it possible to actuate the fan <NUM> in both directions of rotation.

Preferably, the power supply and actuation apparatus <NUM> is accommodated inside a box-like body <NUM> made of sheet metal <NUM> (preferably stainless steel) provided with a thermal insulation layer (inside the sheet metal).

In a particular preferred embodiment, the box-like body of sheet metal <NUM> is a stainless steel structure and its dimensions are <NUM> x <NUM> x <NUM>, but the dimensions can vary depending on the power installed and/or on the dimensions of the elements installed inside.

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

In this case an emergency command is sent remotely to the power supply and actuation apparatus <NUM>, and the latter, by means of the motorized switching unit <NUM>, 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 <NUM>.

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

In more detail, the motorized switching unit <NUM> comprises a motor <NUM> and a series of switches <NUM> actuated by the motor <NUM>.

<FIG>, <FIG> and <FIG> show an example of a box-like body <NUM> containing the power supply and actuation apparatus <NUM>. The latter comprises conventional interface elements <NUM>, <NUM> (switches, button panel for controlling the electronic control system, etc.) and aeration grilles <NUM>.

With reference now to a particular preferred embodiment, the power supply and actuation apparatus <NUM> 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).

The box-like body <NUM> 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.

Also in this preferred embodiment, the power supply and actuation apparatus <NUM> has the following characteristics:.

Furthermore it comprises a harmonics filter LCL TDH <<NUM>% and a circuit breaker with a mechanical impediment that can be padlocked and withstand a temperature of <NUM> for <NUM> hours.

Preferably, the power supply and actuation apparatus <NUM> 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.).

The ventilation system <NUM> for road tunnels can comprise a plurality of fans <NUM>, positioned at various zones of the tunnel, each one provided with a respective power supply and actuation apparatus <NUM>.

The operation of the ventilation system <NUM> is described below.

Under normal conditions the fans <NUM> 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.

The electronic control system of the power supply and actuation apparatus <NUM> regulates the rotation speed of the fan <NUM> in terms of number of rpm and in the most suitable direction of flow, based on the environmental conditions.

In the presence of fire, with the fans <NUM> operating, the fans will be regulated as a function of the location and characteristics of the fire.

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

In the event of a fire when the fans are stopped, the fans <NUM> 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 <NUM>-<NUM> are started in the emergency configuration, as they can operate under these conditions at up to <NUM> for two hours.

In advanced embodiments in which there are a plurality of fans <NUM>, 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.

This control unit in practice comprises a programmable electronic apparatus and is functionally connected to the power supply and actuation apparatuses <NUM> of each fan <NUM> so as to control them.

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.

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.

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

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

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.

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

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

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