Sorting facility with improved compressed air management and corresponding management method
A single pneumatic circuit with a passive overpressure system optimizes compressed air distribution for both ejection and cooling in optical sorting installations, addressing high energy consumption and operational costs by regulating pressure based on external parameters, ensuring efficient and reliable operation.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- PELLENC SELECTIVE TECH
- Filing Date
- 2025-12-11
- Publication Date
- 2026-06-25
AI Technical Summary
Existing optical sorting installations face high energy consumption due to the need for compressed air at varying pressures for ejection and cooling systems, with inefficiencies in managing a single pneumatic circuit supplying both systems, leading to increased operational costs.
A single pneumatic circuit with a passive overpressure means is implemented to regulate and distribute compressed air, allowing controlled pressure adjustment based on external parameters, using a passive booster to supply the cooling system and maintaining efficient operation of the ejection system without direct energy consumption.
This solution reduces energy consumption by optimizing pressure distribution, maintaining high sorting performance while minimizing energy costs and simplifying the pneumatic architecture, enhancing operational efficiency and reliability.
Smart Images

Figure EP2025086479_25062026_PF_FP_ABST
Abstract
Description
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 optical sorting machines and installations equipped with compressed air ejection systems installed at the end of a high-speed sorting conveyor (speed of 2 to 7 m / s) 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 planar geometry sorter, 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 - a detection system capable of analyzing objects moving on the conveyor and classifying them into at least two categories, based on their constituent material, - a compressed air ejection system installed at the outlet end of the belt conveyor and configured to deflect the trajectory of at least one of the categories of objects designated by the detection system, - at least one separation wall between the flows of ejected and non-ejected objects.
[0004] Such an installation also includes a cooling system for at least one component or system and / or at least a part thereof that heats up during operation. Indeed, these optical sorter installations are exposed to ambient temperatures ranging from -18°C to 60°C. 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.
[0005] Although the most obvious solution would be the implementation of air conditioning, the applicant opted for an air cooling solution for reasons of performance stability, reduced maintenance and to guarantee a temperature and dust controlled environment for the installation equipment.
[0006] A known air-cooling technology that meets the aforementioned criteria relies on the use of vortex tubes. The construction and operating principle of these tubes are well understood by those skilled in the art.
[0007] However, to ensure effective cooling via a vortex tube, a pressure of 7 bar is required on its compressed air supply line, while the ejection system only requires a maximum pressure of 5 bar. Indeed, regarding 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 reduced (conductance loss minimized).
[0008] However, the supply of compressed air, in other words the operation of the compressor, constitutes by far the most important energy expenditure item in the operation of a sorting installation such as that referred to herein, and the higher the pressure it has to deliver, the greater the energy consumption of the compressor.
[0009] One obvious first solution to reduce this operating cost could be to implement a seasonal adjustment of the pressure delivered by the The compressor's performance depends on the ambient temperature. In other words, the cooling function is degraded when the compressed air supply pressure drops below 7 bar. Besides the need to adjust the compressor each time a temperature threshold is crossed, determining the most suitable threshold temperature can be difficult depending on the components or system being cooled.
[0010] 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 combined with a single pneumatic compressed air distribution circuit supplied by at least one compressor is the preferred solution, this single distribution circuit supplying both the ejection system and the cooling system.
[0011] The general aim of the invention is to attempt to lower 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 implementing only a single pneumatic distribution circuit preferably supplied by a single compressor.
[0012] 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 installation's pneumatic architecture and modulation of the cooling mode to optimize its efficiency according to the ambient temperature.
[0013] 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 includes at least - a conveyor belt on which the objects to be sorted are spread out to form a single layer - a detection system capable of analyzing objects moving on the conveyor and classifying them into at least two categories, based on their constituent material, - a compressed air ejection system installed at the outlet end of the belt conveyor and configured to deflect the trajectory of at least one of the categories of objects designated by the detection system, - at least one separation wall between the flows of ejected and non-ejected objects, 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 that heats up during the operation of the installation, this cooling system incorporating at least one vortex tube, and, on the other hand, a pneumatic architecture for distributing compressed air supplied by at least one compressor and supplying at least the ejection system and the cooling system, the 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 comprises, between the outlet of the compressor and the single inlet of the pneumatic distribution circuit, a means for regulating the pressure,in that said pneumatic distribution circuit comprises several separate branches corresponding to as many distribution lines supplying respectively the compressed air ejection system, 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 comprises a means for 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.
[0014] 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:
[0015] [Fig. 1] and [Fig. 2] are simplified schematic views of a sorting installation according to the invention, in accordance with two embodiment variants;
[0016] [Fig. 3A] and [Fig. 3B] are symbolic diagrams of the pneumatic compressed air distribution circuit of the installation shown in Figure 2, in accordance with two variant embodiments of the invention;
[0017] [Fig. 4] is a more accurate representation of detail A in figure 3A;
[0018] [Fig. 5] is a symbolic fluidic representation of a practical embodiment of a pneumatic distribution architecture forming part of an installation as shown in Figure 2;
[0019] [Fig. 6] is a schematic representation of an example of a passive overpressure means that can be implemented within the framework of the invention.
[0020] The invention relates primarily, as can be seen from the accompanying drawings, to an installation (1) for sorting objects (2), preferably recyclable ones, with a sorter (3) having a 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, - 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 separation wall (7) between the flows of ejected and non-ejected objects (2).
[0021] 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 which is subject to heating 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 feeding 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.
[0022] According to the invention, the pneumatic architecture consists of a single pneumatic circuit (11) for distributing compressed air supplied by a compressor (12) and powering 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 boosting 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.
[0023] Thanks to these provisions, 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 considered to increase the pressure in the line (14') supplying the cooling system (8), such as, for example, a screw compressor or the like, The invention favours a means of overpressure (16) of a passive nature which does not generate any direct energy consumption.
[0024] The pressure regulation means (13) at the inlet (1 1') 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 Figure 5, the branches (14, 14', 14") of the pneumatic distribution circuit (11) extend as mutually independent supply lines, 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 pressure boosting means (16) and said at least one vortex tube (10), this line (14') being able, if necessary, to branch according to the number of separate elements to be cooled.
[0025] 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.
[0026] 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).
[0027] The use of a passive booster (16), such as the one shown schematically in Figure 6, naturally results in additional compressed air consumption and therefore the supply of a volume of compressed air by the compressor (12), at a pressure adapted for the ejection system (6), at the inlet (11') of the larger pneumatic distribution circuit (11). However, the energy saving resulting from the lower pressure to be delivered more than compensates for this increased volume consumption, and the energy balance is largely positive, as the inventors have verified. As shown in Figure 6, and when used in the preferred pressure context of the invention, the booster (16) advantageously comprises an inlet at pressure P1 (5 bar), an outlet at pressure P2 (7 bar), and an exhaust (E).
[0028] 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), bypassing the vortex tubes (10). This would allow for air scavenging within these systems, or at least some of them, in addition to the cooling provided by the vortex tubes (10). Such a connection inevitably results in pressure losses and therefore an inherent limitation of the flow rate exiting the blower (16). However, this limited flow rate is 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 selectively allow additional cooling by an airflow coming directly from the blower (16), in addition to the airflow from the vortex tube(s) (10), as schematically shown in Figure 4. By associating a compressed air storage tank with the blower, it is possible to stabilize the outgoing flow and thus reduce stress on the blower.
[0029] 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 figure 1).
[0030] 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 boosting means (16), a buffer tank (16') allowing to smooth the pressure and flow rate of the supercharged air flow from said superpressure means (16). Indeed, such a tank (16'), mounted upstream of the vortex tube(s) (10) and preferably just downstream of the supercharger (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 supercharger (16), but also the consumption and flow rate of compressed air downstream of the latter, and therefore limit the number of movements of the supercharger piston (improving its lifespan).
[0031] 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.In addition, the pneumatic circuit (11) for compressed air distribution 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.
[0032] Thus, it is possible to use the compressed air supplied by the compressor (12) at the appropriate pressure for ejection (preferably 5 bar, for example) directly for cooling without using the blower (16) or the vortex tube(s) (10), when the compressed air temperature is lower than the setpoint temperature of the component(s), system, and / or part(5, 9) to be cooled. This limits air consumption for cooling thanks to improved efficiency (avoiding the overconsumption associated with blower operation). Switching between supplying the vortex tube(s) (via the blower) or allowing free exhaust of compressed air (from the compressor) into the component(s), system, and / or part(5, 9) to be cooled can then be achieved using a switching device (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).
[0033] 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 limitation 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).
[0034] 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 particulate, water, and oil contamination of this incoming compressed air. 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).
[0035] 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 part of the installation (1) which is subject to 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).
[0036] This process is characterized in that it consists of subjecting, via a passive overpressure means (16) present in a line (14') of the pneumatic circuit (11) supplying the cooling system (8), the compressed air originating from the compressor (12) to a pressure increase before its injection into the vortex tube(s) (10).
[0037] 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).
[0038] 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.
[0039] It is therefore possible to optimize the efficiency of the cooling function of the installation (1) by controlling the switching device(s) (18), in the form of a distributor for example, arranged upstream of the blower and the vortex tubes in the supply line(s) (14') concerned according to the following logic: - when the temperature of the compressed air is higher than the setpoint temperature, supply the vortex tube(s) to lower the temperature of the air in the line (14') concerned before blowing it into the component or system or the part to be cooled; - when the compressed air temperature is lower than the setpoint temperature, blow the air directly from the inlet (1 1') into the component or system or part to be cooled.
[0040] Furthermore, an improvement in the operational reliability of the installation (1), particularly its cooling function, can be achieved by opting for a short-circuiting of the booster (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 booster (16).
[0041] According to another favorable feature of the invention, 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.
[0042] 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
Demands
1. Installation (1) for sorting objects (2), preferably recyclable, with a sorter (3) of 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, - 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 partition (7) separating 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 that 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 distributing 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) 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), 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 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.
2. Installation according to claim 1, characterized in that 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.
3. 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. Installation according to any one of claims 1 to 4, characterized in that 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 (6, 9) of the installation (1) undergoing heating, for the purpose of its cooling, and in that the pneumatic circuit (11) for distributing compressed air includes one or more switching elements (18) for bypassing the passive overpressure means (16) and the vortex tubes (10) and for supplying the relevant components, system and / or parts (5, 9) with compressed air coming 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 overpressure means (16), for example at said inlet (11') or in the line (14'). of the power supply concerned, and / or a measurement of the outside temperature.
6. An 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 compressed air distribution circuit (1 1 ), 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.