Medical ventilator with air intake circuit including resonators

Abstract

Title of the invention: Medical ventilator with air intake circuit including resonators. The invention relates to a medical ventilator (100) comprising a motorized turbine (200) including an electric motor (201) and a volute (202) including a volute inlet (205); an air intake circuit (300) including an air inlet (301) fluidically connected to the atmosphere and communicating fluidly with the volute inlet (205); and control means (102) controlling the motorized turbine (200). The air intake circuit (300) includes a first resonator element (310) and a second resonator element (320) arranged in the air intake circuit (300) downstream of the air inlet (301), making it possible to reduce or attenuate the noise generated during the operation of the motorized turbine (200). Figure from the summary: Fig. 1

Description

Title of the invention: Medical ventilator with air intake circuit including resonators

[0001] The invention relates to a medical ventilator equipped with an internal air intake circuit supplying a motorized turbine with atmospheric air, on which resonator elements are arranged to attenuate the noise generated by the air suction.

[0002] A medical ventilator is a respiratory assistance device used to provide respiratory assistance, i.e. artificial ventilation, to a person, namely a patient suffering from respiratory disorders or insufficiencies, more or less severe, which may result from different pathologies or the like. Some patients with severe pathologies may remain ventilated in a hospital environment for several days, even several months.

[0003] During operation, the medical ventilator draws in ambient air, filters it and then delivers it to the patient in the form of filtered air that can be enriched with oxygen, by means of a motorized turbine arranged in the peripheral casing or shell of the ventilator. Usually, the motorized turbine, also called a (micro)blower, pump or compressor, comprises an electric motor driving a rotating wheel arranged in a volute. It is supplied with ambient air by an air intake circuit that includes the filter. The air circulates in the air intake circuit by being drawn in by the wheel during its rotations when it is driven by the electric motor, when it is commanded to operate.

[0004] The operation of the fan, in particular that of the motorized turbine, is controlled and piloted by control means, typically one (or more) electronic card with microprocessor(s) arranged in the casing of the fan.

[0005] EP-A-4043776 and EP-A-4044776 describe a fan of this type equipped with a screen carried by a support arm surmounting the fan frame.

[0006] EP-A-3875136 is also known, which proposes a fan with an internal gas circuit comprising an extractable air filter, which supplies the turbine with filtered air.

[0007] The use of a motorized turbine sucking air through the internal air intake circuit creates a known problem of noise related to the circulation of air in the internal air intake circuit, which can be very disturbing or annoying for users, typically medical personnel, or patients receiving the air delivered by the ventilator turbine, in particular during the night when relative calm reigns in hospitals.

[0008] Much of the noise results from the flow of air in the circuit air intake connected to the atmosphere, that is to say the air intake upstream of the turbine.

[0009] A problem is therefore to be able to improve a medical ventilator, in particular a ventilator of the type described by EP-A-4043776 and EP-A-4044776, in order to reduce the sound level, that is to say the noise, generated by the flow of air in the air intake circuit, during operation of the medical ventilator, so as to limit the noise disturbance for the nursing staff and the patients. In other words, the invention aims to propose a quieter medical ventilator.

[0010] A solution of the invention then concerns a medical ventilator, that is to say a respiratory assistance device, comprising: - a motorized turbine (i.e. also called (micro)blower, pump or compressor) comprising an electric motor and a volute comprising a volute inlet, - an air intake circuit comprising an air inlet fluidly connected to the atmosphere, and fluidly communicating with the volute inlet, and - control means controlling the motorized turbine, i.e. a control device or unit.

[0011] According to the invention, the air intake circuit comprises a first resonator element and a second resonator element arranged in the air intake circuit downstream of the air inlet.

[0012] These resonators make it possible to reduce or attenuate the noise level, i.e. the noise generated by the flow of air in the air intake circuit, during operation of the medical ventilator, i.e. the operation of the turbine with air suction due to the rotations of the impeller of the turbine, and thus limit the noise disturbance for the nursing staff and the patients, in particular in a hospital environment.

[0013] Depending on the embodiment considered, the medical ventilator of the invention may comprise one or more of the following characteristics: - the volute defines an internal compartment containing a rotating impeller during its rotations, that is to say when it is driven in rotation by the electric motor. - the volute includes a volute inlet in fluid communication with the internal compartment to supply it with gas, e.g. air. - the volute comprises a volute outlet in fluid communication with the internal compartment to extract a gas flow, e.g. air, from said internal compartment. - the volute comprises a volute outlet in fluid communication with a gas discharge conduit for discharging / conveying the gas flow exiting the internal compartment of the volute. the first resonator element is arranged near the air inlet and the second resonator element is arranged downstream of the first resonator element, the first resonator element is a quarter-wave resonator. the second resonator element is a Helmoltz resonator. it comprises at least one air filtration element arranged in the air intake circuit between the air inlet and the first resonator element. the first resonator element comprises a resonator body defining an internal chamber fluidly communicating with the internal passage of the air intake circuit. the second resonator element comprises a sealed housing crossed by a main conduit comprising one or more internal compartments arranged around the main conduit and in fluid communication with an internal passage of the main conduit. the sealed housing of the second resonator element comprising several internal compartments arranged around the main duct, preferably 4 internal compartments. each internal compartment forms a cavity with a volume of less than 50 cm3. the main duct of the waterproof box is fluidically connected to the fan air intake circuit. the motorized turbine, i.e. also called (micro)blower, pump or compressor, comprising a volute defining an internal compartment containing a rotating impeller during operation of the turbine. the air flow sucked in by the turbine during its operation enters the internal compartment through the volute inlet. The impeller is rotated by the engine, via a motor shaft, during turbine operation. the impeller is carried by the motor shaft. the rotations of the impeller generate an air suction. the turbine volute inlet is in fluid communication with the internal compartment. the turbine volute comprises an outlet, such as a volute outlet, in fluid communication with the internal compartment to evacuate the gas flow leaving the turbine, i.e. from the volute. the gas flow leaving the turbine is conveyed by an air exhaust circuit arranged in the fan, namely one (or more) passages, conduits or analogous. - the operation of the turbine is controlled by the control means - the turbine is controlled by the control means so as to maintain, during its operation, a constant regime, that is to say a constant rotation speed. - alternatively, the turbine is controlled by the control means so as to apply, during its operation, two different regimes, i.e. two different predefined rotation speeds, i.e. one being greater than the other. - it comprises one or more solenoid valves controlled by the control means, preferably one or more proportional solenoid valves. - the control means are configured to control in particular the degree of opening of the proportional solenoid valve(s), i.e. their complete or partial opening, or their closing so as to authorize the circulation of all or only part of the gas flow or, conversely, to prevent it, i.e. to prohibit any circulation of the gas flow. - the solenoid valve(s) are arranged downstream of the turbine outlet, i.e. the volute outlet, namely on the air exhaust circuit, i.e. on the internal circuit carrying the gas downstream of the turbine, i.e. on the gas path. - the ventilator air exhaust circuit is fluidically connected to a patient circuit, preferably a patient circuit supplying a respiratory interface, such as a mask or the like.

[0014] Furthermore, depending on the embodiment considered, the medical ventilator of the invention may also comprise one or more of the following characteristics: - it comprises a screen surmounting the carcass of the ventilator. - the screen is carried by a support arm, via a mounting plate, for example VESA type. - the screen is adjustable. - it comprises an internal support frame formed of a rigid structure, in particular a metal structure, for example made of steel or aluminum alloy, or, alternatively, polymer. - the support frame carries the turbine, the air intake circuit and the means of piloting. - the support frame is formed from a rigid metal alloy structure of aluminum, in particular aluminum alloy type EN AW-5754. - the support frame carries the external peripheral casing of the fan. - the support frame forms a rigid internal frame or skeleton carrying the peripheral carcass so as to reinforce the solidity of the whole while serving as a solid anchor for the support arm. the support arm is fixed, i.e. secured, to the support frame. the supporting arm forms a second rigid structure, preferably metallic. the supporting arm is made of metal, preferably aluminium alloy, in particular aluminium alloy type EN AW-5754 the support arm is integral with the support frame, that is to say fixed to the support frame and projects above the support frame upwards away from it. The support arm is fixed to the support frame by screwing, riveting, welding or other means. The outer casing forms a protective shell around the fan. a display screen orientation system allows the display screen to be oriented relative to the support arm in several directions, i.e. different directions. the support arm forms a gallows or the like supporting the display screen, the orientation system is configured to allow orientation of the display screen along at least two axes (X, Y), preferably two perpendicular axes (X, Y) comprising a horizontal axis (XX) and a vertical axis (YY). the support frame comprises one or more structural elements forming one or more floors, uprights or the like, preferably secured to each other. The support frame carries the other internal components of the medical ventilator, including the battery.... the external carcass is formed of several parts, i.e. several carcass elements, in particular a base and a cover, i.e. a lower part of the carcass in which the support frame is housed and secured, and a removable cover forming a detachable upper part of the carcass. the base is detachably attached to the hood. one or more operating handles allow the display screen to be easily manipulated and oriented, for example two handles arranged on either side of the screen. the support arm is protected by a peripheral protective shell arranged around the support arm and is crossed by at least one connecting and / or electrical cable arranged along the support arm, used to electrically connect the display screen to the fan control means, in particular the electronic elements used to operate the display screen, including an electronic card for controlling the display on the screen and the power supply means. the control means comprise at least one electronic card, preferably at least one pivotally mounted electronic card. the electronic card includes one or more microprocessors. The microprocessor(s) implement algorithms ensuring the operation of the fan, in particular the control of the turbine, the displays on the screen, the triggering of alarms, etc. the motorized turbine, i.e. blower, pump or compressor, supplies a breathing gas, such as air or oxygen-enriched air. the internal gas circuit carries the gas supplied by said blower, i.e. exiting through the turbine outlet. The motorized turbine includes a brushless electric motor. The display screen allows you to display information, curves, selection or adjustment keys, icons or other things. it further comprises a human-machine interface (HMI), preferably the HMI comprises the display screen. the HMI further includes one or more adjustment or selection buttons or keys that can be operated by the user. the display screen is touch-sensitive, preferably it includes one or more touch keys, i.e. virtual keys, displayed on the display screen. it also includes means of supplying electric current. the means of supplying electrical current are electrically connected (directly or indirectly) to the electronic card, to the display screen, to the blower and more generally to all the elements or components of the fan requiring electrical current to operate. the means of supplying electric current include a rechargeable battery. the means of supplying electricity include means of connection to the mains (110 / 220 V), in particular one or more electric cables and / or one or more connection sockets. the support frame also carries one or more cooling fans used to circulate air in the casing in order to cool the electronic card(s), or even other internal components of the ventilator, such as the turbine motor or even heat exchanger blocks promoting heat exchanges so that the gas sent to the patient is not too hot, for example it does not exceed 70°C over a period of 120 seconds or equivalent energy in conditions of approximately 43°C

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[0021] at 100% humidity, i.e. a specific enthalpy of 197 kj / m3 regardless of the ventilation range chosen. - the support frame also carries at least part of the gas circuit (i.e. conduits, valves, etc.). - the chassis also carries an electronic power supply board used to convert the mains voltage (110 / 220V) into a suitable supply voltage compatible with the electronic and other components of the fan. - the support frame also carries the rechargeable power supply battery. - the control means are configured to control the blower so as to deliver gas at least during the patient's inspiratory phases. - the control means are configured to control the accelerations and braking / decelerations of the blower's electric motor. - the display screen includes one or more touch keys for making selections, validations, adjustments, starting or stopping operations, etc. The touch keys are digitally activated, i.e. they are activated when the user presses them with their finger, typically their index finger. - the display screen is configured to display information in the form of alphanumeric characters, graphic representations (e.g. graphs, curves, drawings, icons, etc.), photos, video animations, or others. - the blower is controlled to reach a rotation speed of 25,000 rpm, typically between 500 and 15,000 rpm, for example in the order of 9,500 rpm maximum. The invention will now be better understood thanks to the following detailed description, given for illustrative but non-limiting purposes, with reference to the appended figures among which: [Fig.l] is an embodiment of a medical ventilator according to the invention. [Fig.2] is a side view of the internal parts of the medical ventilator of [Fig.l]. [Fig.3] is a diagram showing the first resonator element arranged on the air intake circuit of the fan of [Fig.l], [Fig.4] is a diagram showing the first and second resonator elements arranged in the air intake circuit of the fan of [Fig.l], [Fig.5] is a diagram showing the second resonator element of [Fig.4], and [Fig.6] is a schematic sectional view of a turbine fitted to the medical ventilator of [Fig.l].

[0022] [Fig.l] and [Fig.2] diagram an embodiment of a medical ventilator 100, i.e. a respiratory assistance device, delivering assisted ventilation to a patient according to the invention.

[0023] The ventilator 100 is designed to supply a respiratory gas to a patient, i.e. a medical gas, in particular air from the ambient atmosphere, possibly enriched with oxygen, i.e. an air / oxygen mixture.

[0024] The medical ventilator 1 comprises a rigid external casing or shell 101, for example made of polymer, in which are arranged the various elements allowing its operation, in particular the motorized turbine 200 of [Fig.6], also called pump, (micro)blower, compressor or the like, delivering the flow of respiratory gas, e.g. air or air / O2 mixture, an internal gas circuit comprising gas conduits or passages and flow management elements, such as valves, non-return valves, etc., to convey the gas flow(s) in the ventilator 1, microprocessor-based control means 202, i.e. a control device or unit, one or more rechargeable batteries or the like, a gas mixer, also called a mixing unit, to produce the desired air / O2 mixtures, etc.

[0025] In this embodiment, the carcass 101 is formed of two (or more) sub-units which are secured to each other, namely a base 101.1 forming the lower or bottom part of the carcass 101 and a cover 101.2 forming the top or upper part of the carcass 101. The cover 101.2 is removable, i.e. can be removed to give access to the inside of the fan 100, in particular during its assembly (i.e. manufacturing) or during its maintenance (i.e. servicing).

[0026] In operation, ambient air is drawn in by the motorized turbine 200, during its operation, via an inlet port or air inlet 301 in fluid communication with the ambient atmosphere and an air intake circuit 300 conveying the air from the inlet port towards the inlet of the turbine 200, as detailed below and illustrated in [Fig.3].

[0027] Preferably, the air is filtered before entering the turbine 200, by filtration means, namely a filter or the like, for example of the HEPA type.

[0028] The motorized pump or turbine 200 has a conventional architecture.

[0029] Thus, [Fig.6] is a schematic sectional view of an embodiment of a conventional turbine 200 which can equip the medical ventilator of [Fig.l] but other architectures can be used within the framework of the invention for which identical or similar noise problems arise.

[0030] The turbine 200 conventionally comprises an electric motor 200 arranged in a protective casing 209, which drives in rotation, during its operation, an axis or motor shaft 207 carrying a bladed wheel 204. The bladed wheel 204 is arranged here to be mobile in rotation in the internal compartment 203 of a volute 202, of preferably sandwiched between a lower half-volt and an upper half-volt fixed in a sealed manner to each other and delimiting between them the internal compartment 203.

[0031] The air sucked in by the impeller 204, during its rotations, enters (arrow F1) into the volute 202 through a volute inlet 205, i.e. an opening or inlet orifice, and leaves (arrow F2) through a volute outlet 206, i.e. an opening or outlet orifice, which here communicates with an air evacuation duct 208.

[0032] In the embodiment of [Fig.6], the volute inlet 205 is located above the volute 202 and the volute outlet 206 used for evacuating the flow is located laterally (i.e. axes of the volute inlet 205 and volute outlet 206 substantially perpendicular here) but, of course, other configurations are possible, depending on the turbine 200 used, for example according to another embodiment, the volute inlet 205 could also be located laterally instead of being on top of the volute 202, for example on an axis substantially parallel to the axis of the volute outlet 206.

[0033] The gas flow, e.g. air, generated by the turbine 200 and delivered by the air exhaust duct 208 is then sent to a patient, via a patient circuit, i.e. one or more gas ducts, supplying a respiratory interface, such as a respiratory mask or the like (not shown). The patient circuit, for example one or more flexible ducts, is fluidically connected in a detachable manner to a gas outlet of the ventilator 100.

[0034] The air can be enriched with oxygen, upstream of the turbine 200 or downstream thereof, by adding oxygen to the air flow entering or leaving the turbine 200, preferably downstream of the turbine 200.

[0035] The motor 201 is powered by electric current from the mains (110 / 220V) and / or from an internal rechargeable battery. Its rotation speed can be up to at least 25,000 rpm, or even more, but is typically between 500 and 15,000 rpm.

[0036] According to one embodiment, the operation of the motor 201 is controlled by the control means of the ventilator 100, for example the accelerations and / or the decelerations / braking of the motor 201, for example as a function of the inspiratory and expiratory phases of the patient.

[0037] According to another embodiment, which is preferred, the speed of the motor 201 is not controlled to achieve the necessary gas flow rate. It is solenoid valves arranged downstream of the turbine 200, that is to say in the air discharge circuit or duct 208, which are involved in the regulation and which define the desired volumes, flow rates and / or pressures. To do this, the control means 102 control the solenoid valves and / or the turbine 200. In this case, only one or two speeds of 200 turbines are implemented.

[0038] Generally speaking, the control means 102 constitute an electronic or similar control device or unit. They typically comprise one or more electronic cards 102.1 with one or more microprocessors, so as to supply the respiratory gas at the desired flow rate and pressure, preferably selected or adjusted by the user via the human-machine interface (HMI) of the ventilator 100.

[0039] The microprocessor(s) are arranged on the electronic card(s), advantageously a microcontroller(s), and implement one or more algorithms, making it possible in particular to monitor and regulate the ventilation delivered to the patient by exploiting in particular pressure and flow rate signals measured by pressure and / or flow rate sensors.

[0040] Indeed, the fan 100 may comprise other elements, in particular one (or more) pressure sensor and / or one (or more) flow sensor (e.g. mass flow sensor and / or hot wire) for measuring the pressure of the gas and / or the flow rate of the gas flow in the internal gas circuit, typically downstream of the turbine 200. The pressure and flow rate measurements (i.e. signals) are transmitted by the sensors to the control means 102 of the fan 1.

[0041] In addition, the electronic card(s) may also comprise storage means for storing in particular the pressure and / or flow rate values, for example a flash type memory or other memory carried by the electronic card, or in any other storage means, including in a microprocessor algorithm.

[0042] Furthermore, the ventilator 100 also comprises a human-machine interface or HMI serving as an adjustment or selection interface for the user, i.e. the healthcare staff. The HMI here comprises a display screen 103 surmounting the casing 101 of the ventilator 100, which is carried by a support arm 104 forming a mast or gallows. The support arm 104 is carried by the internal support frame 107 of the ventilator 100, for example a metal frame, for example stainless steel or the like.

[0043] As visible in [Fig.l], the display screen 103 is protected by a protective casing 103.1 made of rigid polymer, arranged around the screen 103, that is to say along the peripheral edges of the screen 103 and opposite its rear part or face. It delimits an internal compartment containing the electronic elements used to operate the display screen, such as an electronic card, rotary encoder, LED power indicator or other.

[0044] The display screen 103 is a “flat screen”, that is to say it has a flat three-dimensional rectangular shape. Preferably, the screen 103 has a touch screen and can display virtual selection keys or the like.

[0045] In order to allow easy orientation along several axes of the display screen 103, an orientation system 105, such as a VESA 105.1 or other type plate, is arranged between the support arm 104 and the screen 103, which allows orientation along several axes relative to the support arm 104, typically at least 2 perpendicular axes (X, Y), namely here a horizontal axis (XX) and a vertical axis (YY). The orientation and manipulations of the screen 103 are carried out via two lateral handles 106, for example in the form of hoops or the like, arranged on either side of the screen 103, that is to say along the right and left edges of the screen 103, as illustrated in [Fig.l].

[0046] Furthermore, the internal support frame 107 of the fan 100 serves as a support for various elements or components of the fan 100, such as the control means 102, typically the electronic card 102.1, the motorized turbine 200, the internal gas circuits, the battery, etc., as well as the external casing 101 of the fan 100.

[0047] As visible in [Fig.2], connecting cables 108 provided with electrical and mechanical connection connectors electrically connect the screen 103 to the internal elements of the fan 1, in particular to the electrical supply means and to the control means 102 which control the displays on the screen 103. The display screen 103 is preferably a touch screen, and preferably in color, on which are displayed, during its operation, virtual selection or adjustment keys actuable by digital action of a user, that is to say when the user presses on them with his index finger for example. The virtual keys can be in the form of icons or the like.

[0048] We see that the HMI also includes here one (or more) rotary button 109 which is used to vary the values ​​to be set and to voluntarily validate the chosen configurations.

[0049] The supporting frame 107 may also carry a source of electrical current, for example a rechargeable battery, one or more cables with a mains connection plug (110 / 220V), or both, and preferably a power supply card acting as a current / voltage converter, which are used to supply electrical energy to the elements needing it to operate, in particular the turbine 200, the control means 102, in particular the electronic card(s) 102.1 and the microprocessor(s), the pressure and / or flow rate sensors, the display screen 103, and / or other components.

[0050] As illustrated in [Fig.l], the medical ventilator 100 may further comprise other elements, such as an expiratory valve connection 120 for fluidly connecting an expiratory valve, such as the Monnal'EVA™ Valve, used to measure the flow rate of gas exhaled by the patient and released into the atmosphere; an expiratory valve ejection button 121 used to detach the valve from the ventilator 100, for example during maintenance or otherwise; a connector for connecting a nebulizing device 122 for fluidly connecting a nebulizing device used to supply a medication to be nebulized which is mixed with the gas flow respiratory system within the ventilator 100; a probe connection connector 123 for fluidically connecting an esophageal probe to it for measuring the internal pressure from such a probe; a patient circuit connector 124 for connecting the patient circuit to it for conveying the gas flows to the patient; and / or an FiO2 probe housing 125 and its closure cover for storing a probe for measuring the patient's blood O2 level.

[0051] Of course, the fan 100 can also include other operating elements, in particular connectors serving for different connections of the double USB socket type, ADMI connector, RS235 SUB D5 and RJ45 connectors, or others, a speaker, etc.

[0052] According to the invention, as illustrated in [Fig.3] to [Fig.5], in order to reduce noise pollution, i.e. the noise, generated by the suction of air by the turbine 200, when the wheel is rotated, i.e. during its operation, resonator elements 310, 320 are arranged in the air intake circuit 300 of the fan 100, namely a first resonator element 310 and a second resonator element 320. These are arranged in the air intake circuit 300, i.e. downstream of the air inlet 301 and upstream of the volute inlet 205 of the turbine 200, considering the direction of circulation of the sucked air going from the air inlet 301 to the turbine 200.

[0053] According to embodiments, the air intake circuit 300 of the fan 100 may be part of an intake-filtration block or a mixer block, or the like.

[0054] [Fig. 3] is a diagram showing the first resonator element 310 arranged on the air intake circuit 300 of the fan 1 of [Fig. 1], also called an air intake passage or channel or the like. As can be seen, this first resonator element 310 is housed, for example fixed by screwing, in a resonator housing 302 machined in the wall 304 delimiting the internal passage or lumen of the air intake circuit 300. A seal element 14, such as an O-ring, ensures fluid sealing between the external peripheral surface of the first resonator element 310 and the surface of the internal wall of the resonator housing 302.

[0055] In the embodiment of [Fig.3], the first resonator element 310 comprises a resonator body 311 defining an internal chamber 312 fluidly communicating with the internal lumen or passage 300.1 of the air intake circuit 300, via a connecting orifice or channel 303. The first resonator element 310, in particular the resonator body 311, may be made of different materials, such as for example an aluminum alloy or the like.

[0056] A movable adjustment element 313 partially inserted in the internal chamber 312 makes it possible to choose or adjust the internal volume of the internal chamber 312, that is to say to increase or decrease the volume of the internal chamber 312 according to the position that it occupies relative to the connecting orifice 303. Preferably, it can be moved there at the manner of a piston to vary the volume of the internal chamber 312. The adjustment element 313 advantageously carries a seal 315 ensuring a gas seal between the peripheral surface of this adjustment element 313 and the surface of the internal wall of the internal chamber 312. The adjustment element 313 can be fixed by screwing within the internal chamber 312.

[0057] According to another embodiment, the internal volume of the internal chamber 312 is fixed once and for all, that is to say is not adjustable. In this case, the adjustment element is either locked in a fixed position or replaced by a non-movable element closing the internal chamber 312, so as to obtain the desired internal volume.

[0058] In other words, depending on the embodiment chosen, the first resonator element 310 may be adjustable or non-adjustable. When it is adjustable, it is preferably adjustable from the outside, in particular by means of its rear portion forming an extension 313.1 projecting outwards which can be actuated, for example in rotation, by a user to move the adjustment element 313 in the internal chamber 312 and thus vary its internal volume.

[0059] Advantageously, the first resonator element 310 is a quarter-wave resonator whose internal chamber 312 acts as an acoustic cavity. At its tuning frequency, this acoustic cavity 312 compensates for the acoustic wave propagating in the air intake circuit 30. By using a first resonator element 310 of the quarter-wave resonator type, it is possible to reduce the noise pollution (i.e. dB emitted), i.e. the noise generated during suction, by a few dB for the sound peak located at 4500 Hz in “adult patient” ventilation mode and by around ten dB for the sound peak located at 5750 Hz in “a patient suffering from Acute Respiratory Distress Syndrome” (ARDS) ventilation mode. The sound peaks were determined during the tests carried out using the air intake circuit 300 of the fan 100 according to the invention, as explained below.

[0060] To do this, the first resonator element 310 is adjusted to a frequency located between these two frequencies, namely to a frequency of the order of 5300 Hz, by means of the adjustment element 313 by varying the volume of the internal chamber 312 serving as an acoustic cavity. For example, the volume of the internal chamber 312 serving as an acoustic cavity can be adjusted between 2 and 3 cm3, for example approximately 2.6 cm3.

[0061] In fact, during the tests carried out within the framework of the invention, the cavity was first dimensioned theoretically, i.e. by means of mathematical formulas. The theoretical results were then validated on a fan air intake circuit. Thus, the final setting of the cavity by the screw was determined by successive measurement and comparison of acoustic spectra obtained for different settings tested. To do this, in particular, ventilations were started and the total spectrum obtained was recorded, i.e. between 0 and 6000 Hz. The final setting retained, i.e. the dimensions of the cavity, is the one for which the peaks are the most attenuated for frequencies between 4.5 kHz and 5.3 kHz.

[0062] According to another embodiment, the first resonator element 310 can be digitally controlled to have a positive impact, in terms of reducing noise pollution, on several frequencies depending on ventilation modes chosen at the level of the fan 100.

[0063] In order to guarantee good efficiency in the attenuation of harmful sound waves, i.e. suction noise, the first resonator element 310 is preferably positioned in the air intake circuit 300 so as to correspond to one (or more) acoustic pressure “antinodes”, where the pressure level is maximum, in the aforementioned ventilation modes, namely “adult” patient and “ARDS” patient.

[0064] [Fig-4] shows the first resonator element 310, i.e. a quarter-wave resonator, arranged on the air intake circuit 300 of the fan 100, near the turbine 100, and the second resonator element 320 arranged, for its part, in the air intake circuit 300, near the air inlet 301 fluidly connected to the atmosphere, through which the atmospheric air which is sucked in by the wheel 204 of the turbine 200, during its rotations, enters said air intake circuit 300 of the fan 100.

[0065] The exact positioning of the first resonator element 310, i.e. the quarter-wave resonator, on the air intake circuit 300 depends in particular on the acoustic modes of the fluid in question, i.e. the nature of the fluid and the geometry of the cavity. For example, here, the axis of the resonator is positioned perpendicular to the main axis of the flow cavity and 33 mm from the axis of the intake orifice of the turbine. In all cases, the exact positioning of the first resonator element 310 can be determined by simple empirical tests.

[0066] Preferably, filtration means, such as a HEPA filter or other, are provided for example upstream of the port or orifice acting as an air inlet 301 or between the air inlet port 301 and the second resonator element 320 arranged near said air inlet office 301 so that the air sucked into the air intake circuit 300 of the fan 100 is purified air, that is to say free of the pollutants that it may contain, such as dust, microorganisms (bacteria, viruses, spores, etc.) or other aerosols.

[0067] An embodiment of the second resonator element 320 is shown diagrammatically in [Fig. 5]. Given that the noise to be processed is formed of low frequencies, the second resonator element 320 is preferably a Helmholtz resonator.

[0068] In the proposed embodiment, the second resonator element 320 comprises a main conduit 321 around which is arranged a sealed housing 322 comprising a or several internal compartments or chambers 323, for example here 4 internal compartments 323 identical and angularly distributed, i.e. at 90°, around the main conduit 321.

[0069] Here, the case 322 is parallelepipedal in shape but it could have another shape. Its dimensions are of the order of 70 x 70 x 36 mm.

[0070] The internal compartments 323 each form a cavity of given volume, typically less than 50 cm3, for example approximately 25 cm3. Each of the 4 internal compartments 323 communicates with the internal passage 321.1 or lumen, i.e. the interior, of the main conduit 321 via a small junction channel 323 pierced or arranged in the wall of the main conduit 321, typically less than 10 mm in internal diameter and less than 20 mm in length, for example of the order of 7 mm in internal diameter and of the order of 13 mm in length. Of course, the number of internal compartments 323 may be different depending on the embodiment chosen, i.e. greater than or less than 4.

[0071] The main duct 321 is fluidically connected to the air intake circuit 300 of the fan 100, that is to say is inserted into the path of the sucked air which circulates in the air intake circuit 300 of the fan 100. In other words, the main duct 321 constitutes a portion of the air intake circuit 300 of the fan 100.

[0072] Tests carried out within the framework of the invention have shown that using a second resonator element 320 of the Helmholtz resonator type makes it possible to reduce the sound peak located at 420 Hz by at least 10 dB and that located at 860 Hz by approximately 5 dB. To do this, the resonator was adjusted / tuned to a frequency located between these two frequency peaks of “interest”, namely to a frequency of the order of 500 Hz, so as to be more effective on the peak located at 420 Hz.

[0073] The second resonator element 320 can be made with any rigid material, in particular polymer(s), i.e. plastic, for example ABS / PC.

[0074] Generally speaking, the 2 resonators allow sound waves to be trapped in their internal cavities.

[0075] Within the framework of the invention, as already stated, comparative tests were carried out to evaluate the noise level generated at the intake circuit of the turbine, during its operation, without prior filter, for a turbine rotation speed of 6600 rpm with and without quarter-wave resonator (first resonator 310) and Helmoltz (second resonator 320).

[0076] The results obtained showed that, without a resonator, a whistling and a dull noise are perceived during operation of the turbine, whereas with the resonators 310, 320, installed as explained above, only a reduced flow noise is perceived, and without whistling or humming.

[0077] The acoustic measurements carried out show that a gain of 15 dB was obtained on certain lines of the acoustic spectrum and that a gain of approximately 6.7 dB was obtained in terms of acoustic power.

[0078] Generally speaking, the medical ventilator of the invention is particularly well suited to use in a hospital environment.

Claims

Claims

1. Medical ventilator (100) comprising: - a motorized turbine (200) comprising an electric motor (201) and a volute (202) comprising a volute inlet (205), an air intake circuit (300) comprising an air inlet (301) fluidly connected to the atmosphere, and fluidly communicating with the volute inlet (205), the air intake circuit (300) further comprising a first resonator element (310) and a second resonator element (320) arranged in the air intake circuit (300) downstream of the air inlet (301), and - control means (102) controlling the motorized turbine (200), characterized in that: - the first resonator element (310) is a quarter-wave resonator comprising a resonator body (311) defining an internal chamber (312) fluidly communicating with the internal passage (300.1) of the air intake circuit (300), - the second resonator element (320) is a Helmholtz resonator comprising a sealed housing (322) crossed by a main duct (321) comprising several internal compartments (323) arranged around the main duct (321) and in fluid communication with an internal passage (321.1) of the main duct (321), and - air filtration means (330) are arranged between the air inlet (301) and the second resonator element (320).

2. Fan according to claim 1, characterized in that the first resonator element (310) is arranged on the air intake circuit (300) near the turbine (100), and the second resonator element (320) is arranged in the air intake circuit (300), near the air inlet (301) fluidly connected to the atmosphere, through which atmospheric air enters said air intake circuit (300).

3. Fan according to claim 1, characterized in that it comprises one or more solenoid valves controlled by the control means (102), the solenoid valve(s) being arranged downstream of the turbine outlet.

4. Fan according to claim 1, characterized in that the main duct (321) of the sealed housing (322) is fluidically connected to the air intake circuit (300) of the fan (100).

5. Fan according to claim 1, characterized in that the sealed housing (322) of the second resonator element (320) comprises 4 internal compartments (323) arranged around the main duct (321).

6. Fan according to one of claims 1 or 5, characterized in that each internal compartment (323) forms a cavity having a volume of less than 50 cm3.

7. Fan according to claim 1, characterized in that the filtration means comprise a HEPA filter.

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