Sorting plant with improved compressed air management and corresponding management process

Abstract

Sorting installation with improved compressed air management and corresponding management method The invention relates to an installation (1) for sorting objects (2) with a sorter (3) with planar geometry, also comprising, on the one hand, an air cooling system (8) for at least one system (5, 9) thereof which is subject to heating during operation, which incorporates at least one vortex tube (10), and, on the other hand, a pneumatic architecture (11) for distributing compressed air supplied by at least one compressor (12) and supplying at least one pneumatic ejection system (6) and the cooling system (8).An installation characterized in that it comprises a single pneumatic circuit (11) for distributing compressed air supplied by a compressor (12) with a means (13) for regulating the inlet pressure, in that said pneumatic distribution circuit (11) comprises several separate branches (14, 14', 14'') corresponding to as many distribution lines, and in that the line (14') supplying the cooling system (8) comprises a means (16) for passively over-pressurizing the compressed air from the compressor (12) before its injection into the vortex tube(s) (10). Figure to be published with the abbreviation: Fig. 2.

Description

Title of the invention: Sorting installation with improved compressed air management and corresponding management method

[0001] The present invention relates to the field of planar geometry optical sorting machines and installations, equipped with compressed air ejection systems installed at the end of a high-speed (2 to 7 m / s) sorting conveyor belt, and capable of performing binary or ternary sorting, i.e., sorting comprising one or two ejected outputs and one non-ejected output. An installation of this type is, for example, described in document EP 1 243 350 A in the name of the applicant.

[0002] The invention relates more particularly to installations of the aforementioned type in which compressed air is used not only for the selective ejection of objects to be sorted, but also for cooling certain components of the installation that tend to overheat during operation. In this context, the invention relates to an object sorting installation featuring improved management of the supply and use of compressed air, with a particular focus on improving energy efficiency, as well as a corresponding management method.

[0003] An installation related to the invention consists of an object sorting installation, preferably for recyclable objects, incorporating a sorter with planar geometry, in particular binary or ternary, which comprises at least:

[0004] - a belt conveyor on which the objects to be sorted are spread out to form a single layer

[0005] - a detection system suitable and intended to analyze objects circulating on the conveyor and to classify them into at least two categories, based on their constituent material,

[0006] - a compressed air ejection system installed at the outlet end of the conveyor a band and configured to deflect the trajectory of at least one of the categories of objects designated by the detection system,

[0007] - at least one separation wall between the flows of ejected and non-ejected objects.

[0008] Such an installation also includes a water cooling system at least one component or system and / or at least a part thereof that experiences heating during the operation of the installation. Indeed, these optical sorting installations are exposed to external temperatures ranging from -18°C to 60°C. In order to guarantee the longevity of the equipment (electrotechnical components in the electrical cabinets) and the stability of the optical measurements (in the spectroscopic enclosures), it proved necessary to implement active cooling.

[0009] Although the most obvious solution lies in the implementation of air conditioning systems, the applicant has turned to an air cooling solution for reasons of performance stability, reduced maintenance and guarantee of a temperature and dust controlled environment for the installation equipment.

[0010] A known air-cooling technology meeting the aforementioned criteria is based on the use of vortex tubes. The construction and operating principle of these tubes are well known to those skilled in the art.

[0011] However, to ensure effective cooling via a vortex tube, a pressure of 7 bar is required on its compressed air supply line, whereas the ejection system only requires a maximum pressure of 5 bar. Indeed, with regard to the ejection nozzle bar, by positioning the solenoid valves (EVs) as close as possible to the nozzles, the pressure required to achieve sufficient flow for object ejection can be limited (conductance loss minimized).

[0012] However, the supply of compressed air, in other words the operation of the compressor, constitutes by far the most important item of energy expenditure in the operation of a sorting installation such as that referred to herein, and the higher the pressure that it has to deliver, the greater the energy consumption of the compressor.

[0013] One obvious solution for reducing this operating cost could be to implement seasonal adjustment of the compressor's output pressure, based on the ambient temperature. In other words, the cooling function is degraded by reducing the compressed air supply pressure below 7 bar. Besides the need to adjust the compressor each time a temperature threshold is crossed, choosing the most suitable threshold temperature can be difficult depending on the components or system being cooled.

[0014] Another obvious solution for reducing this operating cost is to implement two compressed air distribution circuits at two different pressures, each supplied by a compressor at the required pressure. However, for reasons of design simplicity, cost, and ease of machine integration, a single air inlet associated with a single pneumatic compressed air distribution circuit supplied by at least one compressor is a preferred solution, this single distribution circuit supplying both the ejection system and the cooling system.

[0015] The general aim of the invention is to attempt to reduce the energy consumption of a sorting installation of the aforementioned type in relation to the supply of compressed air, while maintaining a high level of sorting performance and by not implementing that a single pneumatic distribution circuit preferably supplied by a single compressor.

[0016] To achieve this, the proposed solution should first limit the pressure required to supply the entire pneumatic architecture of the installation and operate the pneumatic systems at the required pressures (cooling and ejection), by providing a continuous supply of compressed air. It should also allow for controlled adjustment of pressures for each pneumatic component / system, based on external parameters (humidity, temperature, flow type). Finally, the proposed solution should also, if possible, allow for adaptation of the pneumatic architecture of the installation and modulation of the cooling mode to optimize its efficiency according to the ambient temperature.

[0017] In order to meet at least the main requirements expressed above, the present invention relates to a sorting installation for preferably recyclable objects, with a sorter having a planar geometry, in particular binary or ternary, which comprises at least - a conveyor belt on which the objects to be sorted are spread out to form a single layer

[0018] - a detection system suitable and intended to analyze objects circulating on the conveyor and to classify them into at least two categories, based on their constituent material,

[0019] - a compressed air ejection system installed at the outlet end of the conveyor a band and configured to deflect the trajectory of at least one of the categories of objects designated by the detection system,

[0020] - at least one separating wall between the flows of ejected and non-ejected objects,

[0021] said installation also comprising, on the one hand, an air cooling system for at least one component or system and / or at least a part thereof which is subject to heating during the operation of the installation, this cooling system incorporating at least one vortex tube, and, on the other hand, a pneumatic architecture for the distribution of compressed air supplied by at least one compressor and supplying at least the ejection system and the cooling system,

[0022] An installation characterized in that the pneumatic architecture consists of a single pneumatic circuit for distributing compressed air supplied by a compressor and supplying both the ejection system and the cooling system, in that the installation includes, between the compressor outlet and the single inlet of the pneumatic distribution circuit, a pressure regulation means, and in that said pneumatic distribution circuit comprises several separate branches corresponding to as many distribution lines supplying the system respectively. compressed air ejection, the air cooling system and, where applicable, at least one pneumatic device, such as for example a blow gun, and in that the line supplying the cooling system includes a means of passively overpressurizing the compressed air from the compressor before its injection into the vortex tube(s), the ejection system being supplied by compressed air from the compressor without pressure modification.

[0023] The invention will be better understood from the following description, which relates to preferred embodiments, given by way of non-limiting examples, and explained with reference to the accompanying schematic drawings, in which:

[0024] [Fig-1] and [Fig.2] are simplified schematic views of a sorting installation according to the invention, in accordance with two embodiment variants;

[0025] [Fig.3A] and [Fig.3B] are symbolic diagrams of the pneumatic compressed air distribution circuit of the installation shown [Fig.2], in accordance with two variant embodiments of the invention;

[0026] [Fig.4] is a more precise representation of detail A of [Fig.3A];

[0027] [Fig.5] is a symbolic fluidic representation of a practical embodiment of a pneumatic distribution architecture forming part of an installation as shown [Fig.2];

[0028] [Fig.6] is a schematic representation of an example of a passive overpressure means that can be implemented within the framework of the invention.

[0029] The invention relates firstly, as can be seen from the accompanying drawings, to an installation (1) for sorting objects (2) preferably recyclable, with a sorter (3) with planar geometry, in particular binary or ternary, which comprises at least - a belt conveyor (4) on which the objects (2) to be sorted are spread out to form a single layer, - a detection system (5) suitable and intended to analyze the objects (2) circulating on the conveyor (4) and to classify them into at least two categories, according to their constituent material,

[0030] - a compressed air ejection system (6) installed at the outlet end of the belt conveyor (4) and configured to deflect the trajectory of at least one of the categories of objects (2) designated by the detection system (5),

[0031] - at least one separating wall (7) between the flows of ejected and unejected objects (2) ejected(s).

[0032] This installation (1) also includes, on the one hand, an air cooling system (8) for at least one component or system and / or at least a part (5, 9) thereof that heats up during operation of the installation (1), and, on the other hand, a pneumatic architecture (11) for distributing compressed air supplied by at least one compressor (12) and supplying at least the ejection system (6) and the cooling system (8). The cooling system (8) incorporates at least one vortex tube (10). Preferably, a vortex tube (10) is incorporated directly into the housing of each component, system and / or part (5, 9) to be cooled.

[0033] According to the invention, the pneumatic architecture consists of a single pneumatic circuit (11) for distributing compressed air supplied by a compressor (12) and supplying both the ejection system (6) and the cooling system (8). Furthermore, the installation (1) includes, between the outlet (12') of the compressor (12) and the single inlet (11') of the pneumatic distribution circuit (11), a pressure regulating means (13). Finally, said pneumatic distribution circuit (11) comprises several separate branches (14, 14', 14") corresponding to as many distribution lines supplying respectively the compressed air ejection system (6), the air cooling system (8), and, where applicable, at least one pneumatic component (15), such as, for example, a blow gun.Finally, the line (14') supplying the cooling system (8) includes a means (16) for passively overpressurizing the compressed air from the compressor (12) before its injection into the vortex tube(s) (10), the ejection system (6) being supplied by compressed air from the compressor (12) without pressure modification.

[0034] Thanks to these arrangements, the invention makes it possible, while implementing a simple single-inlet pneumatic architecture (11'), to limit the pressure supplied by the compressor (12) to adequately and controllably supply the entire pneumatic network of the installation (1) and to operate the various pneumatic systems at the required pressures (in particular cooling and ejection). The use of a pressure boosting device (16) mounted in the line (14') supplying the cooling system (8) does not complicate the structure of this pneumatic architecture, while providing the different pressures (low ejection pressure / high cooling pressure) adapted to each of the systems (6 and 8).Although active means can be envisaged to increase the pressure in the line (14') supplying the cooling system (8), such as for example a screw compressor or similar, the invention favors a passive overpressure means (16) which does not generate any direct energy consumption.

[0035] The pressure regulation means (13) at the inlet (11') may include or consist of a pressure gauge; it may be associated with the compressor (12) or form part of the installation (1). Furthermore, as shown in particular in [Fig. 5], the branches (14, 14', 14”) of the pneumatic distribution circuit (11) extend as mutually independent supply lines, but all connected to the single inlet (11') of said circuit (11). Preferably immediately downstream of the inlet (11') and upstream of the subdivision into separate branches of the circuit's line network (11), A set of means forming a compressed air treatment system (19) is advantageously provided (see Figures 3 and 5). In addition, a coalescing filter (21) can be mounted in the line (14') supplying the passive overpressure means (16) and said at least one vortex tube (10), this line (14') being able, where appropriate, to branch according to the number of separate elements to be cooled.

[0036] In accordance with a preferred embodiment of the invention, the passive overpressure means (16) consists of a booster, which advantageously has a ratio between its inlet pressure and its outlet pressure of between 1.2 and 2.0, preferably between 1.4 and 2.0. Such a booster (16) is known in the prior art and may, for example, correspond to a booster of the type known under the designation VBA40 and marketed by the company SMC or of the type known under the designation DPA40 and marketed by the company FESTO.

[0037] In such a pressure-boosting device, compression is achieved by an air-actuated piston. Its usual and known use in the prior art concerns pressure increases for occasional uses: a new application of such a booster is therefore proposed, used in the context of the present invention to produce a continuous blowing in the form of a super-compressed airflow intended to supply the vortex tube(s) (10).

[0038] The use of a passive booster (16), such as the one schematically represented in [Fig. 6], naturally results in additional compressed air consumption and therefore requires the compressor (12) to supply a larger volume of compressed air at a pressure suitable for the ejection system (6) at the inlet (11') of the pneumatic distribution circuit (11). However, the energy savings resulting from the lower pressure required more than compensate for this increased volume consumption, and the energy balance is largely positive, as the inventors have verified. As shown in [Fig. 6], and when used in the preferred pressure context of the invention, the booster (16) advantageously comprises an inlet at pressure PI (5 bar), an outlet at pressure P2 (7 bar), and an exhaust (E).

[0039] One possible way to optimize the overconsumption of the blower (16) could be to connect the blower's (16) exhaust (E) directly to the systems to be cooled (5, 9), i.e., without passing through the vortex tubes (10), in order to perform air purging in said systems or at least some of them, in addition to the cooling generated by the action of the vortex tubes (10). Such a connection inevitably results in pressure losses and therefore an inherent limitation of the flow rate exiting said blower (16), this limited flow rate being, however, sufficient for the intended application within the scope of the present invention. An additional line (22) connected to the exhaust (E) and associated with a pneumatic switching or shut-off means (22') can then be provided to allow selective cooling additional air is supplied by a direct airflow from the blower (16), in addition to the airflow from the vortex tube(s) (10), as schematically shown in [Fig. 4]. By connecting a compressed air storage tank to the blower, it is possible to stabilize the outgoing flow rate and thus reduce the load on the blower.

[0040] In order to be able to control the increased pressure of the compressed air supplied to the cooling system (8) to a predetermined setpoint value and / or to be able to control the value of said increased pressure at the outlet of the blower (16), it may be provided that a pressure switch (17) is mounted downstream or at the outlet of the passive boosting means (16), this passive boosting means (16) being able to be controlled, at the level of its pressure multiplication ratio, by exploiting the measurement of said pressure switch (17) (see [Fig.1]).

[0041] According to an advantageous feature of the invention shown in Figures 2 to 5, the line (14') supplying the cooling system (8) further comprises, downstream of the passive pressure booster (16), a buffer tank (16') for smoothing the pressure and flow rate of the supercharged air flow exiting said pressure booster (16). Indeed, such a tank (16'), mounted upstream of the vortex tube(s) (10) and preferably just downstream of the blower (16), in the main line (14') supplying the cooling system (8), makes it possible to smooth not only the pressure at the outlet of said blower (16), but also the consumption and flow rate of compressed air downstream of the latter, and thus limit the number of movements of the blower piston (improving its service life).

[0042] In accordance with a beneficial constructive variant of the invention, and as shown in Figures 1, 2, 3B and 4, the passive overpressure means (16) is connected to and supplies several vortex tubes (10), each of which is associated with a component, system and / or part (5, 9) of the installation (1) undergoing heating, with a view to its cooling.Furthermore, the pneumatic compressed air distribution circuit (11) may advantageously include one or more switching elements (18) for bypassing the passive pressure boosting means (16) and the vortex tubes (10) and for supplying the relevant components, system and / or parts (5, 9) with compressed air directly from the inlet (11') of said pneumatic distribution circuit (11), these switching elements (18) being controlled according to a temperature measurement of the compressed air (20) taken upstream of the passive pressure boosting means (16), for example at said inlet (11') or in the relevant supply line (14'), and / or an outside temperature measurement.

[0043] Thus, it is possible to use the compressed air supplied by the compressor (12) at the pressure suitable for ejection (preferably 5 bar for example) directly for cooling without using the blower (16), nor the vortex tube(s) (10), when the temperature of the compressed air is lower than the temperature of The setting of the component(s), system and / or part(s) (5, 9) to be cooled allows for limiting air consumption for cooling through improved efficiency (avoiding overconsumption related to the operation of the blower). The switching between supplying the vortex tube(s) (via the blower) or free exhausting compressed air (from the compressor) into the component(s), system and / or part(s) (5, 9) to be cooled can then be achieved using a switching means (18), for example a distributor, controlled according to the temperature of the compressed air in the pneumatic circuit (11) and / or the outside temperature, advantageously measured using suitable sensor(s) (20).

[0044] In addition, it may also be provided, when the temperature of the compressed air is relatively low (in particular below 15°C), and in order to limit the risks of frost formation at the level of the blower (a known limit of this technology), to bypass said blower (16) by means of a distributor controlled according to the temperature of the compressed air, possibly identical to the aforementioned controlled switching means (18).

[0045] Preferably, the installation (1) also includes a compressed air treatment circuit (19) for the air delivered by the compressor (12), preferably mounted immediately downstream of the inlet (11') of the pneumatic distribution circuit (11) and configured to reduce the contamination of this incoming compressed air by particles, water, and oil. Immediately downstream of this circuit (19), the pneumatic circuit (11) can be subdivided into three separate branches (14, 14', 14") corresponding to three distribution lines supplying, respectively, the compressed air ejection system (6), the air cooling system (8), and at least one pneumatic component (15). The line (14') can then, downstream of the blower (16) or the tank (16'), be further subdivided into secondary lines (14') supplying three vortex tubes (10).

[0046] The invention also relates to a method of managing compressed air flows in an installation (1) for sorting recyclable objects (2) with a planar geometry sorter (3), in particular binary or ternary, as described above, and comprising in particular a compressed air ejection system (6), an air cooling system (8) for at least one component or system and / or at least a part of the installation (1) undergoing heating during operation and a single pneumatic circuit (11) for distributing compressed air supplied by a compressor (12) and supplying both the ejection system (6) and the cooling system (8).

[0047] This method is characterized in that it consists of subjecting, by means of a passive overpressure means (16) present in a line (14') of the pneumatic circuit (11) supplying the cooling system (8), the compressed air from the compressor (12) to a pressure increase before its injection into the vortex tube(s) (10).

[0048] In accordance with an advantageous feature of the invention, contributing to an additional improvement in the energy efficiency of the installation (1), the method may consist of short-circuiting the passive overpressure means (16) and the vortex tube(s) (10) when a temperature measurement of the compressed air supplied by the compressor (12) is below a predetermined threshold value, and then supplying said at least one component or system (6) and / or said at least one part (10) of the installation (1), which is subject to heating in operation, with compressed air supplied directly by said compressor (12).

[0049] Preferably, the short-circuiting of the passive overpressure means (16) and the vortex tube(s) (10) is achieved by means of at least one switching element (18) selectively controlled in one of two possible states as a function of a temperature measurement value provided by a sensor (20) measuring the air temperature between the outlet (12') of the compressor (12) and the inlet (11') of the pneumatic compressed air distribution circuit (11), or in the line (14') supplying the cooling system (8), and / or an outside temperature measurement value.

[0050] It is thus possible to optimize the efficiency of the cooling function of the installation (1) by controlling the switching unit(s) (18), in the form of a distributor for example, arranged upstream of the blower and the vortex tubes in the supply line(s) concerned (14') according to the following logic:

[0051] - when the temperature of the compressed air is higher than the temperature of instruction, supply the vortex tube(s) to lower the air temperature in the line (14') concerned before blowing it into the component or system or part to be cooled;

[0052] - when the temperature of the compressed air is lower than the temperature of the Instruction: Blow air directly from the inlet (11') into the component or system or part to be cooled.

[0053] In addition, an improvement in the reliability of operation of the installation (1), in particular of its cooling function, can be obtained by opting for a short-circuiting of the blower (and therefore also of the vortex tubes), when the temperature of the delivered compressed air is below a threshold value (for example 15°C), thus preventing the formation of frost on this blower (16).

[0054] According to another advantageous feature of the invention, the pressure multiplication ratio produced by the passive overpressure means (16) is controlled by pilot control to a predetermined setpoint value by exploiting the measured value provided by a pressure switch (17) installed downstream of the passive overpressure means (16), for example at its outlet.

[0055] Of course, the invention is not limited to the embodiments described and shown in the accompanying drawings. Modifications remain possible, particularly with regard to the composition of the various elements or by substitution of technical equivalents, without departing from the scope of protection of the invention.

Claims

1. Demands Installation (1) for sorting objects (2), preferably recyclable, with a sorter (3) of planar geometry, in particular binary or ternary, which includes at least: - a belt conveyor (4) on which the objects (2) to be sorted are spread out to form a single layer, - a detection system (5) suitable and intended to analyze the objects (2) circulating on the conveyor (4) and to classify them into at least two categories, according to their constituent material, - a compressed air ejection system (6) installed at the exit end of the belt conveyor (4) and configured to deflect the trajectory of at least one of the categories of objects (2) designated by the detection system (5), - at least one separating wall (7) between the flows of ejected and non-ejected objects (2), said installation (1) also comprising, on the one hand, an air cooling system (8) for at least one component or system and / or at least a part (5, 9) thereof which is subject to heating during the operation of the installation (1), this cooling system (8) incorporating at least one vortex tube (10), and, on the other hand, a pneumatic architecture (11) for the distribution of compressed air supplied by at least one compressor (12) and supplying at least the ejection system (6) and the cooling system (8), installation (1) characterized in that the pneumatic architecture consists of a single pneumatic circuit (11) for distributing compressed air supplied by a compressor (12) and supplying both the ejection system (6) and the cooling system (8), in that the installation (1) comprises, between the outlet (12') of the compressor (12) and the single inlet (11') of the pneumatic distribution circuit (11), a pressure regulating means (13), in that said pneumatic distribution circuit (11) comprises several separate branches (14, 14', 14") corresponding to as many distribution lines supplying respectively the compressed air ejection system (6), the air cooling system (8) and, where applicable, at least one pneumatic device (15), such as, for example, a blow gun, and in that the line (14') supplying the system cooling (8) includes a means (16) for passively overpressurizing the compressed air from the compressor (12) before its injection into the vortex tube(s) (10), the ejection system (6) being supplied by compressed air from the compressor (12) without pressure modification.

2. An installation according to claim 1, characterized in that the passive pressure boosting means (16) consists of a booster pump, which advantageously has a ratio between its inlet pressure and its outlet pressure of between 1.2 and 2.0, preferably between 1.4 and 2.

0.

3. V. Installation according to claim 1 or 2, characterized in that a pressure switch (17) is mounted downstream or at the outlet of the passive overpressure means (16), this passive overpressure means (16) being able to be controlled, at the level of its pressure multiplication ratio, by exploiting the measurement of said pressure switch (17).

4. Installation according to any one of claims 1 to 3, characterized in that the line (14') supplying the cooling system (8) further comprises, downstream of the passive overpressure means (16), a buffer tank (16') allowing the pressure and flow rate of the super-compressed air flow exiting said overpressure means (16) to be smoothed.

5. An installation according to any one of claims 1 to 4, characterized in that the passive pressure boosting means (16) is connected to and supplies several vortex tubes (10), each of which is associated with a component, system, and / or part (6, 9) of the installation (1) undergoing heating, for the purpose of its cooling, and in that the pneumatic compressed air distribution circuit (11) comprises one or more switching elements (18) for bypassing the passive pressure boosting means (16) and the vortex tubes (10) and for supplying the relevant components, system, and / or parts (5, 9) with compressed air directly from the inlet (11') of said pneumatic distribution circuit (11), these switching elements (18) being controlled according to a temperature measurement of the compressed air (20) taken upstream of the passive pressure boosting means (16), for example at said inlet (11') or in the relevant power supply line (14'),and / or a measurement of the outside temperature.

6. Installation according to any one of claims 1 to 5, characterized in that it also comprises a compressed air treatment circuit (19) for the compressed air delivered by the compressor (12), preferably mounted immediately downstream of the inlet (11') of the pneumatic distribution circuit (11) and configured to reduce the pollution of this incoming compressed air by particles, water and oil.

7. A method for managing compressed air flows in a sorting installation (1) for recyclable objects (2) with a planar geometry sorter (3), in particular binary or ternary, according to any one of claims 1 to 6, and comprising in particular a compressed air ejection system (6), an air cooling system (8) for at least one component or system and / or at least a part of the installation (1) that heats up during operation, and a single pneumatic circuit (11) for distributing compressed air supplied by a compressor (12) and supplying both the ejection system (6) and the cooling system (8), the method being characterized in that it consists of subjecting, by means of a passive overpressure means (16) present in a line (14') of the pneumatic circuit (11) supplying the cooling system (8),compressed air from the compressor (12) is subjected to a pressure increase before being injected into the vortex tube(s) (10).

8. A method according to claim 7, characterized in that it consists of short-circuiting the passive overpressure means (16) and the vortex tube(s) (10) when a temperature measurement of the compressed air supplied by the compressor (12) is less than a predetermined threshold value, and then supplying said at least one component or system (6) and / or said at least one part (10) of the installation (1), which is subject to heating in operation, with compressed air supplied directly by said compressor (12).

9. A method according to claim 8, characterized in that the short-circuiting of the passive pressure-boosting means (16) and the vortex tube(s) (10) is achieved by means of at least one switching element (18) selectively controlled in one of two possible states as a function of a temperature measurement value provided by a sensor (20) measuring the air temperature between the outlet (12') of the compressor (12) and the inlet (11') of the pneumatic circuit. compressed air distribution (11), or in the line (14') supplying the cooling system (8), and / or an outside temperature measurement value.

10. A method according to any one of claims 7 to 9, characterized in that the pressure multiplication ratio produced by the passive overpressure means (16) is controlled by piloting to a predetermined setpoint value by exploiting the measurement value provided by a pressure switch (17) installed downstream of the passive overpressure means (16), for example at its outlet.

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