FR3126753A1 - Self-calibration of a ventilation installation - Google Patents

Abstract

The invention relates in particular to a ventilation installation comprising: - a central box (2) with a fan (1) for extracting or blowing air, - N ducts for extracting or blowing air (), each connected to an air inlet or outlet of said central box (2); - at least one exhaust or air inlet duct (8), and - a flow regulator () with adjustable passage opening for each air extraction or supply duct (). The installation is characterized in that the central box (2) comprises self-calibration means capable of determining and memorizing in situ a pressure drop coefficient associated with each air extraction or blowing duct ( ). Figure for abstract: Fig. 2

Description

Self-calibration of a ventilation installation

The present invention generally relates to the field of ventilation, and more specifically to a process for self-calibration of a ventilation installation of the VMC (Controlled Mechanical Ventilation) type, comprising:
- a central box comprising a variable speed air extraction or insufflation fan,
- N air extraction or blowing ducts, a first end of each air extraction or blowing duct being connected to an air inlet or outlet tapping of said central box,
- at least one exhaust or air inlet duct, and
- a flow regulator with adjustable passage opening for each air extraction or air supply duct.

Technology background

As shown schematically in Figure 1, a non-limiting example of a known residential ventilation installation comprises a ventilation system comprising a fan 1 for extracting a flow of air at fixed or variable speed, preferably placed in a volute of a central box 2 comprising a number N of air inlet tappings such as the three air inlet tappings visible in Figure 1, each connected to a first end of an air extraction duct , a plurality of air exhaust vents such as the three exhaust vents each connected to the other end of an extraction duct, and at least one rejection device 6 such as a roof cap, connected to an outlet 7 of the central box 2 via a rejection duct 8. The ducts of Extraction equipped with extraction vents lead, for example, into wet rooms (bathroom, toilet, kitchen) and are made up of mechanical parts that can adapt the opening (or passage section) of the air according to one or more parameters such as, without limitation, the humidity level of the room, the detection of the presence of a person, or by any mechanical action (kitchen pull, etc.). The air extraction fan 1 and the extraction vents are generally independent of each other. The air extraction fan 1 extracts an overall air flow by providing the vents with an overall pressure allowing them to operate at the correct extraction flow. Each extraction vent constitutes a flow regulator with adjustable passage opening which operates by modifying the passage section of the air entering the corresponding duct according to humidity or customer needs without taking into account the state of the centralized exhaust fan 1. In a so-called jump speed system depending on the flow, the system can detect a variation in the flow and adapt the speed of the fan 1 in order to modify the pressure available for the vents.

Alternatively, as shown schematically in Figure 2, the extraction vents of Figure 1 are replaced by mouths whose function is purely aesthetic, and the flow regulators with adjustable passage opening are constituted by registers each comprising a movable flap, and placed inside the air inlet tappings of the central box 2. Each damper will adjust the position of the flap in order to meet the extraction rate requirement of the room to which it is connected via the extraction duct, depending on information from sensors such as, but not limited to, humidity sensors, VOCs, etc.

In certain known systems, each tapping is additionally equipped with a flow sensor. Each damper can thus regulate the position of the associated flap to make the flow measured by the flow sensor correspond to a set flow. Flow sensors, however, are expensive devices.

However, to control the extraction flow rates of each room without resorting to expensive flow rate sensors, it is necessary to know precisely on the one hand, the pressure made available by the extraction fan 1, and on the other hand , the pressure drops for each duct of the installation, namely the pressure differences in each duct at a given flow rate. At the first commissioning of a ventilation system with an extraction fan such as that shown schematically in any one of the preceding figures 1 or 2, the pressure losses induced by the aeraulic network specific to the installation are generally unknown. .

In addition, after a certain period of use of the installation, the pressure drops may have changed, for example due to clogging of the extraction ducts.

The object of the present invention is to overcome the limitations of the prior art by proposing a simple solution for precisely determining the pressure drops of a ventilation installation, consisting in determining in situ the pressure drops of the installation, whether either at the time of the first commissioning of the installation, or at any time during the use of the installation.

More specifically, the subject of the present invention is a process for the self-calibration of a ventilation installation comprising:
- a central box comprising an extraction or air blowing fan;
- N air extraction or blowing ducts, a first end of each air extraction or blowing duct being connected to an air inlet or air outlet tapping of said central box;
- at least one exhaust or air inlet duct, and
- a flow regulator with adjustable passage opening for each air extraction or insufflation duct,
said self-calibration method being characterized in that it consists in determining and memorizing in situ a pressure drop coefficient associated with each air extraction or insufflation duct.

In a first possible embodiment, the in situ determination of a pressure drop coefficient k _i associated with the i ^th air extraction or air supply duct comprises the following successive steps:
a) controlling the flow regulator associated with the i ^th air extraction or blowing duct so that it is in an open position and all the other flow regulators so that they are in a closed position;
b) the extraction or air supply fan is activated at a given speed;
c) the flow rate Q _T of the extraction or air supply fan is determined and the difference ΔP between the atmospheric pressure P ₀ and the pressure P ^- made available by the extraction or supply fan is measured air;
d) the pressure drop coefficient k _i is calculated from the determined flow rate Q _T and the measured difference ΔP.

In this case, the pressure drop coefficient k _i can be calculated in step d) by applying the relationship
in which kreg _i is a known pressure drop coefficient of the flow regulator associated with the i ^th air extraction or air supply duct.

In a second possible embodiment, the in situ determination of a pressure drop coefficient k _i associated with the i ^th air extraction or air supply duct comprises the following successive steps:
a) controlling the flow regulator associated with the i ^th air extraction or blowing duct so that it is in an open position and all the other flow regulators so that they are in a closed position;
b) the air extraction or supply fan is activated at a first given speed v1;
c) one determines, for this first given speed, the flow rate of the exhaust or air supply fan and the difference is measured between the atmospheric pressure P ₀ and the pressure P ⁻ made available by the extraction fan or air supply;
d) the air extraction or supply fan is activated at a second given speed v2;
e) determining, for this second given speed, the flow rate of the exhaust or air supply fan and the difference is measured between the atmospheric pressure P ₀ and the pressure P ⁻ made available by the extraction fan or air supply;
f) the head loss coefficient k _i is calculated from the flow rates And determined and differences And measured in steps c) and e).

In this case, the head loss coefficient k _i can be calculated in step f) by solving the system of equations:
in which kreg _i is a known pressure drop coefficient of the flow regulator associated with the i ^th air extraction or supply duct.

In possible embodiments, said open position preferably corresponds to a maximum position for which the flow regulator associated with the i ^th air extraction or blowing duct allows passage of a maximum flow.

In possible embodiments, the method further comprises the determination and memorization in situ of a pressure drop coefficient k _R associated with said at least one exhaust or air inlet duct.

In the case of the aforementioned first embodiment, the in situ determination of the pressure drop coefficient k _R is carried out at the level of step d), by applying the following relationship: where ΔP _v is the known fan pressure.

In this case, the in situ determination of the pressure drop coefficient k _R can be carried out by the following additional steps:
e) all the flow regulators are controlled so that they are in an open position;
f) the extraction or air supply fan is activated at a given speed;
g) the flow rate Q _T of the extraction or air supply fan is determined and the difference ΔP between the atmospheric pressure P ₀ and the pressure P ^- made available by the extraction or supply fan is measured air;
h) the pressure drop coefficient k _R is calculated by applying the following relationship: where ΔP _v is the known fan pressure.

In another possible embodiment in which the air extraction or blowing fan is variable speed, the in situ determination of a pressure drop coefficient associated with each extraction or blowing duct of air and a pressure drop coefficient k _R associated with said at least one exhaust or air inlet duct may comprise the following steps:
a) selecting a pair consisting of a first flow regulator and a second flow regulator of the ventilation installation;
b) controlling the first flow regulator of the selected pair to be in an open position and all the other flow regulators to be in a closed position;
c) activating the extraction or air supply fan at a given speed;
d) determining the flow rate Q _T of the air extraction or supply fan and measuring the pressure ΔP _{v_i} of the air extraction or supply fan;
e) commanding the first flow regulator of the selected pair to be in a closed position, and the second flow regulator of the selected pair to be in an open position;
f) repeating steps c) and d) above so as to determine the flow rate Q _T of the air extraction or supply fan and measure the pressure ΔP _{v_i+1} of the extraction or supply fan air;
g) controlling the first flow regulator and the second flow regulator of the selected pair so that they are simultaneously in an open position;
h) repeating steps c) and d) above so as to determine the flow rate Q _T of the extraction or air supply fan and measure the pressure ΔP _{v_ i _i+1} of the extraction fan 1 or air supply;
i) deducing the values of the coefficients k _i , k _i+1 associated with the two flow regulators of the selected pair, and the coefficient k _R associated with said at least one exhaust or air inlet duct (8);
steps a) to i) being repeated with another pair comprising at least one flow regulator different from those constituting the pair of the previous iteration, until the coefficient of each flow regulator of installation.

The present invention also relates to a ventilation installation comprising:
- a central box comprising an extraction or air blowing fan;
- N air extraction or blowing ducts, a first end of each air extraction or blowing duct being connected to an air inlet or air outlet tapping of said central box;
- at least one exhaust or air inlet duct, and
- a flow regulator with adjustable passage opening for each air extraction or insufflation duct,
said installation being characterized in that the central box comprises self-calibration means able to determine and memorize in situ a pressure drop coefficient associated with each air extraction or blowing duct.

Each flow regulator can be an air extraction or insufflation vent arranged at a second end of the corresponding air extraction or insufflation duct. As a variant, each flow regulator is a damper placed inside the corresponding air inlet or outlet tapping of said central box.

The self-calibration means can also be capable of determining a pressure drop coefficient k _R associated with said at least one exhaust or air inlet duct.

Brief description of figures

The following description with reference to the appended drawings, given by way of non-limiting examples, will make it clear what the invention consists of and how it can be implemented. In the attached figures:
- There , already described above, schematically illustrates a ventilation installation with adjustable extraction vents;
- There , already described above, schematically illustrates a ventilation installation with adjustable extraction registers;
- There [ ] represents a modeling of the pressure drops corresponding to a ventilation installation with adjustable extraction dampers from the ;
- There illustrates possible steps for a first self-calibration method in accordance with the present invention;
- There illustrates possible steps for a second self-calibration method in accordance with the present invention.

Description of embodiment(s)

In the figures, identical or equivalent elements will bear the same reference signs. The various diagrams are not to scale.

In a ventilation installation as shown schematically in the , the pressure drops induced by the aeraulic network depend on the one hand, on each extraction branch (each branch comprising an extraction duct and, at the two ends of the duct, an extraction mouth and a damper extraction), and on the other hand, of the rejection branch or branches (each rejection branch comprising a rejection sheath and a roof cap).

There represents a model of the aeraulic network of an installation similar to that represented schematically on the , comprising N branches referenced B₁to B_NOT. The following notations and references are used for this diagram:
-P^-is the pressure provided by the air extraction fan 1 at the level of the central box 2;
-P₀is the atmospheric pressure (considered hereinafter as zero for the sake of simplification);
- ΔP is the difference between the pressure P₀and the pressure P^-provided by exhaust fan 1;
-P_Ris the pressure at the outlet 7 of the central box 2, connected to the rejection duct 8;
-k_Ris a pressure drop coefficient of the rejection branch composed of the rejection sheath 8 and of the rejection means 6;
- ΔP_vEast the pressure generated by the fan;
- ΔP_Iis the head loss of the rejection branch;
-B_Iis an i^thbranch of the aeraulic network (i being an integer varying from 1 to N);
-P_Iis the pressure at the inlet of the 5" damper_Ibranch B_I;
- ΔP_Iis the head loss created by the 5" damper_Ibranch B_I;
-ΔPg_Iis the created head loss of branch B_I, outside register 5"_I, in other words, the pressure drop associated with the extraction duct 4_I;
- kreg_Iis the pressure drop coefficient created by the 5" register_Ibranch B_I, for a given register position 5"_I;
-k_Iis the head loss coefficient associated with branch B_I, outside register 5"_I, in other words, the pressure drop coefficient associated with the extraction duct 4_I;
-Q_Iis the flow at each branch B_I;
-Q_Tis the airflow of exhaust fan 1.

The air extraction fan 1 can be a fan whose turbine rotates at a fixed speed. Alternatively, the fan may be variable speed. In this case, it is possible to control the speed of rotation of the turbine (for example by a control at constant speed or at constant pressure or at constant flow, or at constant torque).

It is known that the pressure drop ΔPg _i can be calculated conventionally by the following relationship (1):

in which a is a coefficient making it possible to take into account the turbulent effects due to friction inside the ducts which modify the behavior of the head loss.

In possible implementations of the method according to the invention, it can be considered that this coefficient a is equal to 2, so that the relation (1) above becomes the following relation (2):

A self-calibration method according to the invention aims to allow self-calibration means included in the central box 2 (typically a controller not shown) to determine in situ at least the coefficient k _i of loss of load associated with each sheath of each branch B _i of the installation. The coefficients k _i thus determined are stored in a memory (not shown) associated with the controller. At the end of the self-calibration, the controller is then able to calculate, at any time during operation of the ventilation installation, the actual pressure drop ΔPg _i of a 4i duct of the branch B _i for any flow rate Q _i , by application of the first equality of the relation (1) or (2).

Several self-calibration methods in accordance with the present invention will now be described. All these methods consist in determining in situ at least the coefficients k _i of pressure drop for all the ducts of the installation, by controlling the registers so that they occupy different opening positions, according to a particular sequencing differing from from one method to another, and by measuring or estimating in situ the flow rates Q _T obtained at different stages of the sequencing. These methods differ from each other depending on whether or not one has, in the ventilation system (in this case in the central box 2), a sensor for measuring the difference ΔP between the pressure P ₀ and the pressure P ^- made available by the air extraction fan 1.

Case 1: ΔP measurement available
It is assumed in this case that the ventilation system is equipped, inside the central box 2, with a pressure sensor (not shown) which measures the value ΔP. This pressure sensor has a measuring point placed between the roof of the airflow airflow extraction fan 1 and the air inlet tappings 3₁, ...3_I, ...3_NOT, and another measuring point outside to measure the atmospheric pressure P₀ serving as a reference.

There represents the possible steps for implementing a self-calibration method in accordance with the present invention:

The method preferably begins with a preliminary phase 100 aimed at defining the reference (setting to zero) of the position of the flaps of the various 5" dampers _i and at estimating the internal air leaks of the installation. Knowledge by the controller of the position of the registers can in fact be made necessary according to the technology used for these registers, for example in the non-limiting case where these registers use a stepper motor without position sensor to change the position of the register, i.e. that is to move a shutter between an open position and a closed position corresponding to mechanical stops.

The preliminary phase 100 begins with a step 101 during which the controller, preferably positioned inside the central box 2, sends each register 5" _i (i varying from 1 to N) a stop search order. When all the dampers are in abutment, the controller commands the closing of all the dampers (step 102) so that each damper 5″ _i finds itself in a closed position in which it allows the passage of a minimum leak rate.

The controller then activates the air extraction fan 1 at at least a given speed and triggers the measurement or the estimation of the air flow rate Q _T of the fan (step 103). This measurement or estimation can be implemented in various ways.

A first solution consists in using a map of the fan previously stored in the memory associated with the controller, this map giving on the one hand the value of the flow rate Q _T according to the power absorbed by the fan, its speed of rotation and of its control, and on the other hand, the pressure P ⁻ made available by the air extraction fan 1 according to the flow rate Q _T . Thus, by measuring the power consumed and the speed of the fan, it is possible to obtain an estimate of the flow rate Q _T , and of the pressure P ⁻ .

Another solution can be used if fan 1 is a reaction fan. Indeed, in this case, the curves linking the pressure P ⁻ to the flow rate Q _T for different fan speeds are one-to-one. The measurement of the pressure P ^- by the pressure sensor thus makes it possible to deduce the flow rate Q _T.

Other solutions could consist of measuring the pressure difference in the roof and the air intake in the central box 2.

Whatever the solution chosen to measure or estimate the flow Q _T , this measured or estimated flow must be very low and corresponds only to the internal leaks of the casing since all the registers are closed.

If the flow rate Q _T measured or estimated corresponding to the internal leaks is too high, for example greater than a stored threshold Q _fthreshold in the memory associated with the controller, this may mean that an air inlet is not closed (no tapping connected, cap missing on the box, etc.). In this case, the controller preferably generates a visual and/or audible alarm (step 104) and the self-calibration process ends, until the problem is resolved.

Otherwise, the preliminary phase 100 ends with a step 105 during which the controller stores in its associated memory the value of the measured or estimated flow rate Q _T , divided by the number N of registers, so as to be able to take into account later counts these per-register leak values.

The self-calibration process can be continued by the steps making it possible to determine at least the pressure drop coefficient k _i of each sheath 4 _i in each branch B _i , and preferably also the pressure drop coefficient k _R of the rejection sheath.

Sub-case 1: the coefficient a is equal to 2 :

As seen previously, the pressure drop ΔPg _i can be calculated in this case by equation (2) given above. Thus, each pressure drop coefficient k _i can be determined by the following equation (3):

in which is a function translating the behavior of the 5'' damper _i depending on the flow rate Q _i and the opening position α of the damper and is the pressure drop coefficient created by register 5" _i of branch B _i , for a given position of register 5" _i . Each register having been characterized beforehand, the values And are known for each possible flow value Q _i and for each possible position α of the register, and stored in the memory associated with the controller.

The following steps are carried out to calculate each head loss coefficient k _i and the head loss coefficient k _R of the rejection branch:

The controller commands the opening, preferably maximum, of a single 5" damper_I, for example the register 5"₁(i=1) and closing all other registers (step 110). The controller then commands the start of fan 1 at a given speed (any), which allows the system to deliver an available pressure P^-(step 120).

During a step 130, the controller triggers the measurement of ΔP (by the pressure sensor) and the measurement of the air flow Q _T according to any of the methods described above. As only the 5" _i damper is in the open position, the air flow Q _T measured corresponds to the flow Q _i in the branch B _i , except for tapping leaks, so that the controller can proceed (step 140) to the calculation the pressure drop coefficient by applying the following relationship (4):

During this step 140, the controller can also proceed to the calculation of the pressure drop coefficient k _R of the rejection branch by applying the following relationship (5):

where ΔP _v is the fan pressure obtained by mapping, as described above.

At the end of step 140, the memory associated with the controller has the pressure drop coefficient k _i for the branch B _i tested and the pressure drop coefficient k _R .

Steps 110 to 140 are repeated until the pressure drop coefficients associated with the N branches have been determined.

It can be seen that according to this method, the calculation of the pressure drop coefficient k _R of the rejection branch is carried out at each iteration of steps 110 to 140. In practice, the values of k _R obtained at each iteration are never equal. A choice must then be made by a method making it possible to obtain the value of k _R closest to reality, for example by performing an average of the values of k _R obtained at each iteration.

Sub-case 2: the coefficient a is not equal to 2 :

As seen previously, the pressure drop ΔPg _i can be calculated in this case by relation (1) given above. Thus, each head loss coefficient k _i and the head loss coefficient k _R can be determined by the following relationships (6):

with corresponding to the pressure drop coefficient created by register 5" _i of branch B _i , for a given position of register 5" _i .

Steps similar to steps 110 to 140 and described above will in this case have to be carried out to calculate each pressure drop coefficient k _i and the pressure drop coefficient k _R of the rejection branch. Nevertheless, to be able to overcome the lack of knowledge of the coefficient a, the steps 120 and 130 seen above must be carried out not for a single speed of the air extraction fan 1, but for at least two different speeds v1 and v2 of fan 1, so as to have two pairs of measurements And , and solve the following system of equations (7):

in which is the difference ΔP for the speed v1; is the difference ΔP for the speed v2; is the flow rate Q _T for the speed v1; is the rate Q _T for the speed v2; is the fan pressure, obtained by mapping, for speed v1; And is the fan pressure, obtained by mapping, for speed v2.

Variant for determining the coefficient k _R :

• le contrôleur commande l’ouverture, de préférence maximale, de l’ensemble des N registres, puis commande alors le démarrage du ventilateur 1 à une vitesse donnée (quelconque), ce qui permet au système de délivrer une pression disponible P^-;
• le contrôleur déclenche la mesure de ΔP (par le capteur de pression), et la mesure ou l’estimation du débit d'air Q_Tet de la pression disponible P^-selon l’une quelconque des méthodes décrites ci-avant. Comme tous les registres sont en position ouverte, le débit d’air Q_Tmesuré correspond à la somme des débits Q_idans la branche B_i, aux fuites de piquages près ;
• le contrôleur détermine alors le coefficient de perte de charge k_Rpar application de la relation (5).

In the process described with reference to the , we have seen that the calculation of the pressure drop coefficient k _R of the rejection branch was carried out at each iteration of steps 110 to 140. As a variant, however, this calculation can be carried out independently, for example before or after all the pressure drop coefficients k _i have been calculated by applying relations (4) or (7) indicated above and stored in the memory associated with the controller. To do this, one can proceed for example as follows, in the case where the coefficient a is equal to 2:

• the controller commands the opening, preferably maximum, of all of the N registers, then commands the starting of the fan 1 at a given speed (any), which allows the system to deliver an available pressure P ⁻ ;
• the controller triggers the measurement of ΔP (by the pressure sensor), and the measurement or estimation of the air flow Q _T and of the available pressure P ^- according to any of the methods described above. As all the dampers are in the open position, the measured air flow Q _T corresponds to the sum of the flow rates Q _i in the branch B _i , except for tapping leaks;
• the controller then determines the pressure drop coefficient k _R by applying equation (5).

It is noted that the preceding steps could be carried out for any positions of the registers. Nevertheless, the maximum opening of the registers is preferred because the higher the total bit rate Q _T , the greater the precision on the calculation of K _R .

In the case where the coefficient a is not equal to 2, the first two previous steps are carried out for two different speeds v1 and v2 of the fan 1, so that the controller can then determine the pressure drop coefficient k _R by resolution of relation (7b) above.

It should be noted that the determination of the coefficient k _R is not obligatory here in the sense that the knowledge of this coefficient is not used to determine the bit rate in each Q _i branch.

Case 2 : ΔP measurement not available
Unlike the previous case, it is assumed here that the ventilation system does not have any pressure sensor and is therefore not able to measure the value ΔP.

There represents the possible steps for implementing a self-calibration method in accordance with the present invention and particularly suited to this case, and for which the fan 1 is here a variable-speed fan:

The method preferably begins with the preliminary phase 100 aimed at defining the reference (zeroing) of the position of the flaps of the various 5" dampers _i and at estimating the internal air leaks of the central box 2, described above in reference to the .

The controller must then proceed by selecting pairs of registers, as will be described below:

The controller commands the opening, preferably maximum, of a first 5" damper_Iof a first branch B_I, for example the register 5"₁(i=1) and closing all other registers (step 210). The controller then commands the start of fan 1 at a given speed (any), which allows the system to deliver an available pressure P^-(step 220).

During a step 230, the controller triggers the measurement or the estimation of the air flow Q _T according to any one of the methods described above. As only the first damper 5" _i is in the open position, the air flow Q _T measured corresponds to the flow Q _i in the first branch B _i , except for tapping leaks. During step 230, the controller also triggers the measurement of the value ΔP _{v_i} which corresponds to the pressure of the fan 1 when only the first register of the first branch B _i is open This measurement is obtained by using the map of the fan, as stored in the memory associated with the controller.

The controller then commands the closing of the first register 5"_I, and the opening, preferably maximum, of a second register 5"_i+1of a second branch B_i+1, for example the register 5"₂and (step 240). Steps similar to steps 220 to 230 are then applied for this second branch B_i+1. Thus, the controller commands the start of fan 1 at a given speed (any), which allows the system to deliver a new available pressure P^-(step 250). Then, during a step 260, the controller triggers the measurement of the air flow Q_Tusing any of the methods described above. As only the second register 5"_i+1is in the open position, the air flow Q_Tmeasured corresponds to the flow rate Q_i+1in the second branch B_i+1, except for tapping leaks. During step 260, the controller also triggers the measurement of the value ΔP_{v_i+1}which corresponds to the pressure of fan 1 when only the second register of the second branch B_i+1is open.

The controller then controls the simultaneous opening, preferably maximum, of the registers of the first branch B _i and of the second branch B _i+1 (step 270), then controls the starting of the fan 1 at a given speed (any), and triggers the measurement of the air flow Q _T according to any one of the methods described above (step 290). As the first and second dampers of the branches B _i and B _i+1 are in the open position, the measured air flow Q _T corresponds to the sum of the flow rates Qi and Q _i+1 in the first and the second branch, at the near tapping leaks. During step 290, the controller also triggers the measurement of the value ΔP _{v_ i _ i+1} which corresponds to the pressure of fan 1 when only the first register and the second register of the first branch B _i , respectively the second branch B _i+1 , are open.

At the end of step 290, the memory associated with the controller therefore has three pairs of measurements, namely:
- the pair (Q _i ; ΔP _{v_i} ) obtained in step 230;
- the pair (Q _i+1 ; ΔP _{v_i+1} ) obtained in step 260;
- the pair (Q _T ; ΔP _{v_ i _i+1} ) obtained in step 290;

These three pairs of values are sufficient to allow the controller to perform, during a step 300, the calculations of the pressure drop coefficients k _i , k _i+1 and k _R . Indeed, according to the modeling represented on the , when only the first register of the first branch B _i is open (steps 220 and 230), we have the following relation (8):

(8)
or, by combining with relation (2) given above, the following relation (9):

Moreover, when only the second register of the second branch B _i+1 is open (steps 250 and 260), we have the following relation (10):

(10)
or, by combining with relation (2) given above, the following relation (11):

Finally, when the first register and the second register of the branches B _i and B _i+1 are simultaneously open (steps 280 and 290), we have the following relationship (12):

With the relationships (9), (11) and (12) above, the controller has a system of three equations with three unknowns consisting of the three pressure drop coefficients k _i , k _i+1 and k _R sought and can therefore calculate and then store these coefficients in step 300.

Steps 210 to 300 are repeated for another pair of branches, until all the pressure drop coefficients k _i have been calculated. One can for example, as indicated on the , increment i by the value 2 if N is even or by the value 1 if N is odd. The process then ends when the incremented value of i is greater than N in the case where N is even, or is equal to N in the case where N is odd.

As in the case of the method described with reference to the , it is noted that the calculation of the pressure drop coefficient k _R of the rejection branch is carried out at each iteration of steps 210 to 300. In practice, the values of k _R obtained at each iteration are never equal. A choice must then be made by a method making it possible to obtain the value of k _R closest to reality, for example by performing an average of the values of k _R obtained at each iteration.

In summary, when the system does not have a pressure sensor allowing it to measure or estimate the value ΔP, the method according to the consists of:
a) selecting a pair consisting of a first register and a second register;
b) controlling (step 210) the first register of the selected pair to be in an open position and all the other registers to be in a closed position;
c) activating (step 220) the air extraction fan 1 at a given speed;
d) determining (step 230) the flow rate Q _T of the air extraction fan (1) and measuring the pressure ΔP _{v_i} of the air extraction fan 1;
e) controlling (step 240) the first register of the selected pair to be in a closed position, and the second register of the selected pair to be in an open position;
f) repeating steps c) and d) above so as to determine (260) the flow rate Q _T of the air extraction fan 1 and measure the pressure ΔP _{v_i+1} of the air extraction fan 1 ;
g) controlling (step 270) the first register and the second register of the selected pair so that they are simultaneously in an open position;
h) repeating steps c) and d) above so as to determine (290) the flow rate Q _T of the air extraction fan 1 and measure the pressure ΔP _{v_ i _ i+1} of the extraction fan 1 air;
i) deducing (step 300) the values of the coefficients k _i , k _i+1 associated with the two registers of the selected pair, and the coefficient k _R .

Steps a) to i) above are repeated for another pair of registers comprising at least one register different from those constituting the pair of the previous iteration, until the coefficient associated with each is obtained. sheath of the installation.

The self-calibration methods in accordance with the invention have been described in a non-limiting manner in the case of an air extraction ventilation installation. The principles of the invention are nevertheless applicable to the case where the ventilation installation is air-blown. It suffices in this case to replace the air extraction fan 1 with an air supply fan. The N air extraction ducts become air insufflation ducts, and the rejection duct 8 becomes an air inlet duct, preferably equipped with an air filter. In this case, the pressure drop of this filter must be taken into account in the calculation of the coefficient k _R . In addition, the methods have been described within the framework of the installation schematized in FIG. 2 for which the flow regulators with adjustable passage opening are dampers installed in the tappings of the central box 2. As a variant, the flow regulators can be adjustable outlets schematized on the installation of the .

In any case, it is possible to launch a self-calibration procedure at any time, whether it is on the first installation of the central box 2 and the associated outlets, or after this first installation (for example during an operation of maintenance, or following an incident), and thus to know precisely the pressure drop coefficients of the environment in which the ventilation system operates. Thanks to the invention, it is possible in particular to regularly re-evaluate the coefficients k _i , and thus estimate the state of fouling of the ducts. In the case of an air blowing installation, a regular reassessment of the coefficient k _R also makes it possible to assess the state of clogging of the air inlet duct filter, and to change it if necessary.

Claims (14)

Process for self-calibration of a ventilation installation comprising:
- a central box (2) comprising a fan (1) for extracting or blowing air;
- N air extraction or supply ducts ( ), a first end of each air extraction or insufflation duct ( ) being connected to an air inlet or outlet ( ) of said central box (2);
- at least one exhaust or air inlet duct (8), and
- a flow regulator ( ; ) with adjustable passage opening for each air extraction or air supply duct ( ),
said self-calibration method being characterized in that it consists in determining and memorizing in situ a pressure drop coefficient associated with each air extraction or insufflation duct ( ). Method according to claim 1, in which the in situ determination of a pressure drop coefficient k _i associated with the i ^th air extraction or air supply duct comprises the following successive steps:
a) the flow regulator (5″ _i ) associated with the i ^th air extraction or blowing duct is controlled (110) so that it is in an open position and all the other flow regulators to they are in a closed position;
b) the fan (1) for extracting or blowing air is activated (120) at a given speed;
c) determining (130) the flow rate Q _T of the fan (1) for extracting or blowing air and measuring the difference ΔP between the atmospheric pressure P ₀ and the pressure P ^- made available by the fan ( 1) air extraction or supply;
d) the pressure drop coefficient k _i is calculated (140) from the determined flow rate Q _T and the measured difference ΔP. Method according to Claim 2, in which the pressure drop coefficient k _i is calculated in step d) by applying the relationship
in which kreg _i is a known pressure drop coefficient of the flow regulator (5''i) associated with the i ^th air extraction or supply duct. Method according to claim 1, in which, the air extraction or supply fan (1) being at variable speed, the in situ determination of a pressure drop coefficient k _i associated with the i ^th duct d Extraction or blowing of air comprises the following successive steps:
a) the flow regulator (5″ _i ) associated with the i ^th air extraction or blowing duct is controlled (110) so that it is in an open position and all the other flow regulators to they are in a closed position;
b) the fan (1) for extracting or blowing air is activated at a first given speed v1;
c) one determines, for this first given speed, the flow rate of the fan (1) for extracting or insufflating air and measuring the difference between the atmospheric pressure P ₀ and the pressure P ⁻ made available by the fan (1) for extracting or blowing air;
d) the fan (1) for extracting or blowing air is activated at a second given speed v2;
e) determining, for this second given speed, the flow rate of the fan (1) for extracting or insufflating air and measuring the difference between the atmospheric pressure P ₀ and the pressure P ⁻ made available by the fan (1) for extracting or blowing air;
f) the head loss coefficient k _i is calculated from the flow rates And determined and differences And measured in steps c) and e). Method according to claim 4, in which the head loss coefficient k _i is calculated in step f) by solving the system of equations:
in which kreg _i is a known pressure drop coefficient of the flow regulator (5''i) associated with the i ^th air extraction or supply duct. Method according to any one of Claims 2 to 5, in which the said open position corresponds to a maximum position for which the flow regulator (5'' _i ) associated with the i ^th extraction or air supply duct allows the passage of a maximum flow. Method according to any one of the preceding claims, further comprising the determination and memorization in situ of a pressure drop coefficient k _R associated with said at least one exhaust or air inlet duct (8). Method according to Claims 2 and 7, in which the in situ determination of the pressure drop coefficient k _R is carried out at the level of step d), by applying the following relationship:

where ΔP _v is the known fan pressure. Method according to claims 2 and 7, in which the in situ determination of the pressure drop coefficient k _R is carried out by the following additional steps:
e) all the flow regulators are controlled so that they are in an open position;
f) the fan (1) for extracting or blowing air is activated at a given speed;
g) determining the flow rate Q _T of the air extraction or supply fan (1) and measuring the difference ΔP between the atmospheric pressure P ₀ and the pressure P ^- made available by the fan (1) d extraction or air supply;
h) the pressure drop coefficient k _R is calculated by applying the following relationship:

where ΔP _v is the known fan pressure. Process according to Claims 1 and 7, in which, the air extraction or supply fan (1) being variable-speed, the in situ determination of a pressure drop coefficient associated with each extraction duct or air insufflation and a pressure drop coefficient k _R associated with said at least one exhaust or air inlet duct (8) comprises the following steps:
a) selecting a pair consisting of a first flow regulator and a second flow regulator of the ventilation installation;
b) controlling (210) the first flow regulator of the selected pair to be in an open position and all other flow regulators to be in a closed position;
c) activating (220) the fan (1) for extracting or blowing air at a given speed;
d) determining (230) the flow rate Q _T of the air extraction or supply fan (1) and measuring the pressure ΔP _{v_i} of the air extraction or supply fan (1);
e) controlling (240) the first flow regulator of the selected pair to be in a closed position, and the second flow regulator of the selected pair to be in an open position;
f) repeating steps c) and d) above so as to determine (260) the flow rate Q _T of the fan (1) for extracting or blowing air and measuring the pressure ΔP _{v_i+1} of the fan ( 1) air extraction or supply;
g) controlling (270) the first flow regulator and the second flow regulator of the selected pair to be simultaneously in an open position;
h) repeating steps c) and d) above so as to determine (290) the flow rate Q _T of the fan (1) for extracting or blowing air and measuring the pressure ΔP _{v_ i _i+1} of the fan (1) for extracting or blowing air;
i) deducing (300) the values of the coefficients k _i , k _i+1 associated with the two flow regulators of the selected pair, and the coefficient k _R associated with said at least one exhaust or air inlet duct ( 8);
steps a) to i) being repeated with another pair comprising at least one flow regulator different from those constituting the pair of the previous iteration, until the coefficient of each flow regulator of installation. Ventilation installation including:
- a central box (2) comprising a fan (1) for extracting or blowing air;
- N air extraction or supply ducts ( ), a first end of each air extraction or insufflation duct ( ) being connected to an air inlet or outlet ( ) of said central box (2);
- at least one exhaust or air inlet duct (8), and
- a flow regulator ( ; ) with adjustable passage opening for each air extraction or air supply duct ( ),
said installation being characterized in that the central box (2) comprises self-calibration means able to determine and memorize in situ a pressure drop coefficient associated with each air extraction or blowing duct ( ). Ventilation installation according to Claim 11, in which each flow regulator ( ) is an air extraction or insufflation vent arranged at a second end of the air extraction or insufflation duct ( ) corresponding. Ventilation installation according to Claim 11, in which each flow regulator ( ) is a damper placed inside the air inlet or outlet tapping ( ) corresponding to said central box (2). Ventilation installation according to any one of claims 11 to 13, in which the self-calibration means are also capable of determining a pressure drop coefficient k _R associated with said at least one exhaust or inlet duct d air (8).