Centrifugal compressor with auxiliary additive supply

Abstract

The invention relates to a centrifugal compressor (1) with a volute (2), wherein the compressor is motor-driven and supplied with a gas mixture (A) in a closed circuit. The volute (2) comprises: - a pipe (2g) connected to an external source for supplying a gaseous additive (O); - a pressurised chamber (2h) for the auxiliary supply of the additive (O) to the internal volume (2a) of the volute (2), and for separating this internal volume (2a) from the housing (3) of the electric motor (3a), this pressurised chamber (2h) being connected to the pipe (2g); and - a bore (2i) dimensioned so as to regulate, in co-operation with a pressure (P3) established in the pressurised chamber (2h), which is higher than a pressure (P2) in the internal volume (2a) of the volute (2), a one-way diffusion of the additive (O) from the pressurised chamber to the toroidal cavity.

Description

[0001] DESCRIPTION

[0002] CENTRIFUGAL COMPRESSOR WITH AN AUXILIARY SUPPLY OF ADDITIVE

[0003] TECHNICAL FIELD

[0004] The invention relates to the field of motorized devices for delivering a gas regulated in pressure, flow rate and composition, such as in particular a respiratory assistance gas. This type of device, also called a centrifugal compressor, is mainly used to provide respiratory assistance to a patient during a surgical operation. In addition, this type of device can also be used in a closed circuit to deliver a mixture of specific gases containing, for example, an anesthetic product.

[0005] STATE OF THE ART

[0006] In the field of anesthesia machines, the gas generation system generally operates in a closed loop, i.e., by supplying the machine with air directly exhaled by the patient. This closed loop operation allows the reuse of anesthetic gases. The exhaled air flow is then enriched with an adjuvant, such as oxygen, before being delivered to the patient in order to maintain the quantity of oxygen in the case of anesthesia, the generation of pressure in the air circuit being done by a bellows.

[0007] Such a system benefits from a total seal with regard to the generation of the patient airflow, this seal making it possible to isolate the patient airflow from the other components of the machine which, advantageously, do not need to be disinfected. However, these bellows anesthesia machines are not very reactive, the bellows mechanically limiting a dynamic and variable supply of oxygen to the patient airflow.

[0008] The use of motorized devices for regulated gas delivery as illustrated in patent document US 2023 / 0166062, makes it possible to provide dynamic and variable respiratory assistance to a patient. These devices commonly comprise a housing housing a motor for driving a turbine, generally a bladed wheel. The turbine driven by the motor generates a flow of compressed air of the gas to be delivered.

[0009] The enclosure also includes an air circuit through which circulates the air flow from which the gas to be delivered originates. The air flow circulates through the air circuit from an air inlet, through which the air flow is admitted into the interior of the device, to an air outlet through which the air flow is evacuated from the device.

[0010] The air inlet is notably composed of a volute promoting the admission and the dynamics of the air flow to be delivered circulating through the device. The volute is then provided with a connection member to an intake duct of the adjuvant for its mixing with the air flow circulating through the volute.

[0011] The motor is more specifically a servo-controlled electric motor used to regulate the pressure and flow rate of the air flowing through the device, and consequently to regulate the pressure and flow rate of the gas delivered by the device.

[0012] For closed circuit operation, enrichment is generally carried out towards the air inlet of the device so as not to modify this device and so that the mixture is as homogeneous as possible when passing through the device's turbine.

[0013] Such a motorized device, presented for example in patent document US8302598, does not, however, allow, on the one hand, to isolate the gas mixture from the engine and, on the other hand, to ensure that the composition of the delivered gas corresponds to the desired mixture. Thus, such a device is regularly brought in for maintenance to disinfect all of its components and in particular the motorized elements (engine, bearings, etc.), causing on the one hand immobilization of the device and on the other hand its rapid wear. The performance and lifespan of the device are thus severely limited.

[0014] STATEMENT OF THE INVENTION

[0015] The main objective of the invention is to overcome the drawbacks of the state of the art, in particular to optimize an air-adjuvant mixture at the outlet of a motorized gas delivery device, by supplying auxiliary adjuvant to this motorized device in the vicinity of the air outlet.

[0016] To provide the auxiliary adjuvant to the air-adjuvant mixture and to avoid losses of this mixture in the engine, the invention provides an auxiliary supply source for the adjuvant separate from the air inlet of the motorized device.

[0017] More specifically, the present invention relates to a motorized centrifugal compressor powered by a gas mixture, this compressor comprising:

[0018] - an electric motor installed in a housing, the electric motor driving a rotating motor shaft;

[0019] - a volute defining an interior volume isolated from an external environment, the volute having an air inlet, an air outlet as well as a base secured to the housing, this base being perforated by at least one hole and crossed by a rotation shaft;

[0020] - a wheel installed in the interior volume of the volute, this wheel being driven by the rotation shaft, and

[0021] - a compression cavity for the gas mixture.

[0022] The centrifugal compressor being supplied in a closed circuit, the volute base also includes:

[0023] - a conduit connected to an external source of supply of a gaseous adjuvant;

[0024] - a pressurized chamber for auxiliary supply of additive to the interior volume of the volute and for segregating this interior volume with the housing of the electric motor, this pressurized chamber being crossed by the rotation shaft and being connected to the conduit, and - a clearance in the drilling around the rotation shaft, this clearance being dimensioned to regulate, in cooperation with a pressure established in the pressurized chamber greater than a pressure in the interior volume of the volute, a unidirectional diffusion of the additive from the pressurized chamber towards the compression cavity.

[0025] Advantageously, the external source of supply of an adjuvant makes it possible to produce new gas mixtures without modifying the supply system installed at the air inlet of the volute, thus improving the adaptability of the compressor.

[0026] Advantageously, the pressurized chamber also allows the gases to be segregated in a closed circuit of the compressor and therefore seals the motor housing against these gases. This segregation protects the motor from the compressor gases, so a standard housing and motor, i.e. without specific protection against gas mixtures, can be used.

[0027] Also advantageously, drilling with clearance for the rotation axis to pass through the base of the volute makes it possible to avoid:

[0028] - heating by friction of the rotation axis on the base of the volute, this heating causing a rise in temperature both of the motor and its casing, but also of the gas mixture in the compressor. In the case of a respiratory assistance machine, such heating modifies the temperature and the flow rates of the gases sent to the patient;

[0029] - erosion by friction and consequently pollution of the patient circuit by eroded particles.

[0030] According to preferred embodiments taken alone or in combination:

[0031] - the motor axis is the rotation shaft;

[0032] - the air inlet of the volute is coaxial with the rotation shaft;

[0033] - the volute is composed of a lower volute comprising the base and an upper volute;

[0034] - a clearance optimization pad is installed in the hole in the volute base;

[0035] - the optimization pellet is ground in; - the optimization pellet is resistant to anesthetic gases;

[0036] - the volute, the wheel and the rotation shaft are resistant to anesthetic gases;

[0037] - the gaseous adjuvant is oxygen (O2);

[0038] - the motor, housing and rotating shaft are resistant to oxygen corrosion;

[0039] - the pressure in the pressurized auxiliary supply chamber is controlled by the pressure in the interior volume of the volute so that the unidirectional diffusion is constant;

[0040] - the external source supplies the pressurized chamber with a constant flow of gaseous adjuvant;

[0041] - the compression cavity is toroidal;

[0042] - the compression cavity has an evolving section.

[0043] PRESENTATION OF FIGURES

[0044] Other characteristics and advantages of the present invention will emerge from the following reading of a detailed example of embodiment without limiting its scope, with reference to the appended figures which represent, respectively:

[0045] - figure 1, a sectional illustration of an example of a centrifugal compressor according to the invention;

[0046] - figure 2, an exploded perspective view of the constituent elements of the centrifugal compressor according to figure 1;

[0047] - figure 3, an exploded perspective view, illustrating the pressurized auxiliary supply chamber of this compressor;

[0048] - figure 4a and figure 4b, two variants of an enlargement of figure 1, illustrating in section the clearance zone around the rotation shaft of said compressor, and - figure 5, a diagram of the closed circuit operation of said centrifugal compressor.

[0049] DETAILED DESCRIPTION

[0050] The figures and their detailed, non-limiting description set forth the invention in particular ways that are not restrictive as to the scope of the invention as defined by the claims. The figures and their detailed description may serve to better understand and define the invention, if necessary in relation to the general description which has just been given. In the figures, identical reference signs refer to the same element as well as to the corresponding passages of the description.

[0051] In Figure 1, the centrifugal compressor 1 is shown in a sectional view, this centrifugal compressor 1 being motorized and supplied by a gas mixture A composed of air and anesthetic gas, for example sevoflurane associated or not with nitrous oxide. The centrifugal compressor 1 comprises:

[0052] - an electric motor 3a installed in a housing 3, the electric motor 3a driving a rotating motor shaft 3b merged in this embodiment with the rotation shaft 3c;

[0053] - a volute 2 defining an interior volume 2a isolated from an exterior environment 4, the volute 2 having an air inlet 2b, an air outlet 2c as well as a base 2d secured to the housing 3, this base 2d being perforated with a hole 2i and crossed by the rotation shaft 3c;

[0054] - a wheel 2e installed in the interior volume 2a of the volute 2, this wheel 2e being driven by the rotation shaft 3c, and

[0055] - a compression cavity 2f of the gas mixture A.

[0056] The 2d base of volute 2 also includes:

[0057] - a conduit 2g connected to an external source S of supply of a gaseous adjuvant O;

[0058] - a pressurized chamber 2h for auxiliary supply of additive to the interior volume 2a of the volute 2 and for segregation of this interior volume 2a with the housing 3 of the electric motor 3a, this pressurized chamber 2h being crossed by the rotation shaft 3c and being connected to the conduit 2g, and

[0059] - a clearance in the bore 2i around the rotation shaft 3c, this clearance being dimensioned to regulate - in cooperation with a pressure P3 in the pressurized chamber 2h greater than a pressure P2 in the interior volume 2a of the volute 2 - a unidirectional diffusion of the adjuvant O from the pressurized chamber 2h towards the compression cavity 2f here toroidal or alternatively of evolving section.

[0060] Drilling 2i is described more precisely below with reference to Figure 4.

[0061] The electric motor 3a is rotating, its rotating motor shaft 3b being connected to the housing 3 via two ball bearings 3d. In rotation, the electric motor 3a therefore drives the rotation shaft 3c mechanically connected to the wheel 2e of the volute 2, thus sucking in the gas mixture A through the air inlet 2b. This gas mixture A then circulates along the wheel 2e and is compressed in the compression cavity and then expelled from the centrifugal compressor 1 through the air outlet 2c of the volute 2 to be administered to the patient in this embodiment.

[0062] Such a centrifugal compressor 1 is used here as a respiratory assistance machine during operations under general anesthesia. Indeed, this centrifugal compressor 1 makes it possible to supply a patient with a mixture of air containing in particular oxygen and an anesthetic gas according to a so-called closed circuit operating mode detailed with reference to Figure 5. In other uses, the centrifugal compressor can be supplied by other gas mixtures.

[0063] According to one embodiment, the air inlet 2b of the volute is coaxial with the rotation shaft 3c which is merged with the axis of the motor 3b. Alternatively, the axis of the motor can drive the rotation of the rotation shaft using drive mechanisms composed in particular of belts and / or gears. These solutions advantageously make it possible to separate the motor housing from the volute and thus isolate it. However, in this variant, the respiratory assistance machine thus configured loses compactness. The drive mechanisms can also include gears which make it possible to adapt a motor by multiplying or demultiplying the rotation speed of its axis. The exploded perspective views of Figure 2 and Figure 3 show the different constituent elements of the centrifugal compressor 1. The rotation shaft 3c comes out of the housing 3 of the electric motor 3a, this rotation shaft 3c being inserted into the base 2d of the volute 2.The volute 2 is composed of a lower volute 2j comprising the base 2d and an upper volute 2k, the wheel 2e being inserted between the lower volute 2j and the upper volute 2k on the rotation shaft 3c.

[0064] The air inlet 2b is positioned on the upper volute 2k, in the axis of the rotation shaft 3b. The air outlet 2c is formed at the interface between the upper volute 2k and the lower volute 2j by two half-cylinders 2I and 2m respectively. Alternatively, the air outlet 2c can be positioned either on the upper volute 2k or on the lower volute 2j.

[0065] Figure 3 illustrates in particular the pressurized chamber 2h and the conduit 2g. The pressurized chamber 2h is formed in a cylindrical body 2n, integral with the base 2d of the volute 2 and assembled to the housing 3 of the electric motor 3a (see Figure 1). This body 2n is dimensioned to provide a safety distance to the housing 3 during disinfection of the centrifugal compressor. The segregation of the gas mixture A in the interior volume 2a of the volute 2 advantageously isolates said housing from the motor, only the volute 2 then needing to be disinfected. The centrifugal compressor can then be immersed in a disinfectant bath without requiring disassembly of the motor housing, the cylindrical body 2n providing a buffer zone that can be immersed and visually indicating the level of immersion required to completely disinfect the volute 2.

[0066] Furthermore, Figure 4a and Figure 4b show two variants of the drilling 2i of the base 2d of the volute 2, the drilling 2i being crossed by the rotation shaft 3c. In the first variant illustrated in Figure 4a, the drilling 2i forms the bore of the base 2d, the clearance 2o being produced during the machining of the drilling 2i. In the second variant shown in Figure 4b, a clearance optimization pellet 2p is installed in the drilling 2i of the base 2d of the volute 2 or alternatively covers the drilling. This optimization pellet 2p is advantageously lapped to allow a minimization of the clearance 2o, this clearance 2o determining the passage space from the pressurized chamber 2h to the interior volume 2a and therefore regulating the auxiliary supply of gaseous adjuvant O, here oxygen.

[0067] The external source S supplies the pressurized chamber 2h with a constant flow of gaseous adjuvant O. Alternatively, the pressure in the pressurized chamber 2h can be controlled by the pressure prevailing in the interior volume 2a of the volute 2 to maintain the unidirectional diffusion of the adjuvant constant.

[0068] According to other embodiments, the elements of the centrifugal compressor 1 are resistant to the gases with which they are in contact. Thus, the optimization pellet 2p, the volute 2, the wheel 2e and the rotation shaft 3c are resistant to the anesthetic gases of the gas mixture A. Similarly, the electric motor 3a, the housing 3 and the rotation shaft 3c are resistant to corrosion by oxygen.

[0069] Figure 5 illustrates the closed-circuit operation of the centrifugal compressor 1 in the context of use as a respiratory assistance machine. The gas mixture A is a mixture inspired and expired by a patient P under general anesthesia. The operation is said to be in a closed circuit because the anesthetic gases circulate only in the volute 2 of the centrifugal compressor 1 to be inspired and then expired by the patient P. The exhaled air is then purified by extraction E of undesirable gases, such as carbon dioxide, then enriched by an intake B, in particular with oxygen, to regenerate the gas mixture A which is reintroduced through the air inlet 2b (see figure 1). This quantity of oxygen is then adjusted to take into account the auxiliary supply of adjuvant O from the pressurized chamber 2h (seefigure 1), this auxiliary supply advantageously allows the gas mixture containing the anesthetic gases to be confined to the volute and therefore to participate in the closed circuit operation.

Claims

CLAIMS 1. Centrifugal compressor (1) powered by a gas mixture (A), this centrifugal compressor (1) comprising: - an electric motor (3a) installed in a housing (3), the electric motor (3a) driving a motor shaft (3b) in rotation; - a volute (2) defining an interior volume (2a) isolated from an external environment (4), the volute (2) having an air inlet (2b), an air outlet (2c) as well as a base (2d) secured to the housing (3), this base (2d) being perforated with at least one hole (2i) and crossed by a rotation shaft (3c); - a wheel (2e) installed in the interior volume (2a) of the volute (2), this wheel (2e) being driven by the rotation shaft (3c), and - a compression cavity (2f) of the gas mixture (A); the centrifugal compressor (1) being characterized in that it is supplied in a closed circuit and in that the base (2d) of the volute (2) comprises: - a conduit (2g) connected to an external source (S) of supply of a gaseous adjuvant (O); - a pressurized chamber (2h) for auxiliary supply of additive (O) to the interior volume (2a) of the volute (2) and for segregating this interior volume (2a) with the housing (3) of the electric motor (3a), this pressurized chamber (2h) being crossed by the rotation shaft (3c) and being connected to the conduit (2g), and - a clearance (2o) in the bore (2i) around the rotation shaft (3c), this clearance (2o) being sized to regulate, in cooperation with a pressure (P3) established in the pressurized chamber (2h) greater than a pressure (P2) in the interior volume (2a) of the volute (2), a unidirectional diffusion of the adjuvant (O) from the pressurized chamber (2h) towards the compression cavity (2f).

2. Centrifugal compressor (1) according to claim 1, characterized in that the motor axis (3b) is the rotation shaft (3c).

3. Centrifugal compressor (1) according to any one of claims 1 or 2, characterized in that the air inlet (2b) of the volute (2) is coaxial with the rotation shaft (2c).

4. Centrifugal compressor (1) according to any one of claims 1 to 3, characterized in that the volute (2) is composed of a lower volute (2j) comprising the base (2d) and an upper volute 5. Centrifugal compressor (1) according to any one of claims 1 to 4, characterized in that an optimization pellet (2p) is installed in the bore (2i) of the base (2d) of the volute (2).

6. Centrifugal compressor (1) according to claim 5, characterized in that the optimization pellet (2p) is lapped.

7. Centrifugal compressor (1) according to any one of claims 5 to 6, characterized in that the optimization pellet (2p) is resistant to anesthetic gases.

8. Centrifugal compressor (1) according to any one of claims 1 to 7, characterized in that the volute (2), the wheel (2e) and the rotation shaft (3c) are resistant to anesthetic gases.

9. Centrifugal compressor (1) according to any one of claims 1 to 8, characterized in that the adjuvant (O) is oxygen.

10. Centrifugal compressor (1) according to any one of claims 1 to 9, characterized in that the electric motor (3a), the housing (3) and the rotation shaft (3c) are resistant to corrosion by oxygen.

11. Centrifugal compressor (1) according to any one of claims 1 to 9, characterized in that the pressure (P3) in the pressurized auxiliary supply chamber (2h) is controlled by the pressure in the interior volume (2a) of the volute (2) so that the unidirectional diffusion is constant.

12. Centrifugal compressor (1) according to any one of claims 1 to 9, characterized in that the external source (S) supplies the pressurized chamber (2h) with a constant flow of adjuvant (O).

13. Centrifugal compressor (1) according to any one of claims 1 to 12, characterized in that the compression cavity (2f) is toroidal.

14. Centrifugal compressor (1) according to any one of claims 1 to 12, characterized in that the compression cavity (2f) has an evolving section.

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