FR2852852A1 - Artificial respirator, for the delivery of air to a patient, has a valve to inject a secondary gas into the air stream with two rotating disks, for a selective passage opening and pressed together to prevent leakage - Google Patents

Abstract

An artificial respirator has a valve (33) for connection to a secondary gas supply, to enrich the respiration gas. The valve, giving a selective supply, has two disks (331,332) with movement against each other to align their openings (3311,3321) or block the passage through them. The artificial respirator has a valve (33) for connection to a secondary gas supply, to enrich the respiration gas. The valve, giving a selective supply, has two disks (331,332) with movement against each other to align their openings (3311,3321) or block the passage through them. The two disks are pressed together to prevent an escape of the secondary gas in their contact zone, and ensure that the selective flow passages are controlled. A seal (333) is pressed against the disk structure by a spring. The valve operation is through a motor (M), controlled by the respirator at the patient.

Description

The present invention relates to a breathing aid device

  comprising a source of pressurized gas capable of generating a flow of respiratory gas intended for a patient, and a secondary admission valve connected to said source for the selective admission of a secondary gas intended to enrich said respiratory gas.

  Devices of this type are already known.

  The source of pressurized breathing gas may be a compressed breathing gas reservoir (air or mixture). It can also be a source capable of compressing a gas flow 10 in real time (centrifugal compressor for example).

  The secondary inlet valve makes it possible to inject a secondary gas, if necessary, into the respiratory gas, with which it is desired to enrich said respiratory gas.

  The secondary gas can thus be oxygen - or generally a therapeutic gas.

  FIG. 1 schematically represents a first embodiment of such a device 10 of known type.

  This device 10 comprises a source 11 of pressurized respiratory gas (for example air), intended for a patient P. The gas is brought to the patient via a conduit 12, and a nozzle. 13 (shown here in the form of a mask).

  Sensors and device control means, not shown, are also provided.

  The source 11 comprises a mixing chamber 110, into which also opens an inlet 111 for the admission of a secondary gas (oxygen for example).

  The input 111 can be placed in communication with a source 14 of secondary gas.

  This communication must be done in a selective and controlled manner, since it is desired to be able to operate the device by providing the patient with a respiratory gas more or less enriched in secondary gas with a controlled dosage, or not enriched at all.

  To control the rate of secondary gas in the gas supplied to the patient, means for controlling the admission of secondary gas are therefore necessary.

  In the case of the device in FIG. 1, these means for controlling the admission of secondary gas are produced in the form of a network of all-or-nothing solenoid valves 1121 to 1125, arranged on parallel conduits which are associated with the entry 111.

  Each of these solenoid valves can be controlled individually by the control means of the device (which we recall that they are not shown).

  In order to control the quantity of secondary gas which is injected, it is possible to provide that each of the solenoid valves lets through a given flow rate of secondary gas, possibly different from the flow rate associated with the other solenoid valves.

  In the case illustrated here (5 solenoid valves in parallel), it is thus possible to provide that in the open position the various solenoid valves 1121 to 1125 allow the following flow rates to flow respectively (in liters per minute): 1, 20 2, 4, 8, 16 .

  By selecting with the control means the desired solenoid valves, it is thus possible to approach a desired secondary gas flow rate.

  Note, however, that the precision of such a device is not optimal.

  In addition, such a device has a relatively complex structure.

  Furthermore, such a device results in a relatively high electrical consumption, which is disadvantageous (particularly if it is desired to produce a portable device powered by electric batteries).

  And the operation of such a device is relatively cumbersome to manage. It is also noisy, which is another drawback.

  Another type of device is also known, which has a structure and an operation which are not exposed to the drawbacks mentioned above.

  Document FR 2 812 203 describes a breathing aid device the source of respiratory gas of which is a centrifugal compressor of the centrifugal fan type (that is to say, the outlet is at the periphery of the rotating element, for example by a collection channel with tangential outlet), with axial air inlet (i.e. the air inlet of which is substantially aligned with the axis of the rotating part of the compressor centrifugal).

  This centrifugal compressor is shown in FIG. 2, with the reference 21.

  It includes an inlet 211 for the admission of a secondary gas, which opens directly inside a volute 210.

  The volute 210 corresponds to the region in which the blades of the centrifugal compressor rotate to generate a flow of respiratory gas, expelled through an outlet 212.

  Here again, it is important to precisely control the dosage of the quantity of secondary gas injected into the source 21.

  This can be done by a secondary inlet valve, as mentioned in the document FR 2 812 203 (see in particular p. 22 I. 6-1 1).

  As has been said, such a device is free from the drawbacks mentioned above with respect to the device of FIG. 1.

  The object of the present invention is to further improve such a device.

  In order to achieve this object, the invention provides a breathing aid device comprising a source of pressurized gas capable of generating a flow of respiratory gas intended for a patient, and a secondary intake valve connected to said source for the selective admission of a secondary gas intended to enrich said respiratory gas, the means for the selective passage of gas from said valve comprising two elements movable relative to one another to selectively match openings of the two elements, characterized in that the movement of the said two elements of the selective gas passage means is a plane-on-plane movement and compression means are provided to help achieve the following functions: 5. press the said two elements together one on the other in order to prevent secondary gas leaks in the contact area of said two elements, * and to guarantee that the opening of the selective passage means gas is done on a regular basis.

  Other aspects, objects and advantages of the invention will appear more clearly on reading the following description of the invention made with reference to the drawings of the appended figures in which, in addition to FIGS. 1 and 2 which have already been commented on above. above: * FIG. 3 represents, from a first perspective, an exploded view of part of a breathing aid device able to generate a flow of respiratory gas according to the invention to a patient (certain elements not shown for reasons of clarity in this view), * FIG. 4 represents from a different perspective certain elements of the part of the device shown in FIG. 3.

  FIGS. 3 and 4 thus represent a casing or pneumatic block element 31, which is intended to receive: * in a housing 310, a centrifugal compressor (not shown) which can be similar to the centrifugal compressor 21 of FIG. 2, * in a housing 31 1, a regulator 32 intended to be placed upstream 25 of means for selective passage of gas from the device and downstream of a secondary gas source (not shown), * in a housing or cavity 312, a valve d secondary inlet 33 connected to the secondary gas source via the regulator 32, for the selective intake of secondary gas.

  The secondary gas can, as indicated above, be any gas with which it is desired to selectively and in a controlled manner enrich the respiratory gas which will be delivered by the centrifugal compressor.

  It can in particular be a therapeutic gas, for example oxygen.

  The housing 310 is shaped so as to receive the centrifugal compressor. We distinguish in Figure 3 a cavity 3101 which allows to bring into this housing the secondary gas from the housing 312 after passing through the secondary inlet valve when the latter is in the open position.

  It is specified that this cavity 3101 is preferably shaped so that the arrival in the centrifugal compressor of secondary gas takes place tangentially with respect to the rotating parts of the centrifugal compressor.

  The housing 311 has a cavity 3111 for collecting secondary gas leaks from the regulator.

  It is specified in fact that the regulator 32 regulates an outlet pressure (for example at a value of the order of 1.5 bar), from a higher inlet pressure which corresponds to the pressure of the gas source secondary (for example of the order of 2 to 6 bars).

  And the operation of this type of regulator involves leakage of secondary gas, in particular to compensate for variations in atmospheric pressure.

  The cavity 3111 is thus located opposite a leak outlet hole of the regulator (not visible), when the regulator is placed in the housing 311.

  FIG. 3 also shows a leakage pipe 3112, which is in communication with the cavity 3111, as well as with the inlet of the centrifugal compressor.

  The leakage pipe 3112 thus makes it possible to recover the secondary gas resulting from leaks from the regulator 32 to reinject it at the inlet of the centrifugal compressor.

  The housing 311 is also associated with an orifice 3113 which is located opposite the outlet of the regulator 32 when the latter is mounted.

  More specifically, in the mounted position the regulator 32 is pressed against a wall 3114 delimiting the housing 311 and which is crossed by the orifice 3113, so that the contact between the outlet of the regulator and the orifice 3113 is sealed.

  In order to guarantee this tightness, a member 341 for fixing the regulator is engaged through the orifice 3113 which crosses the wall 3114, so as to press the regulator against this wall 3114.

  To this end, the end of the member 341 which faces the regulator is provided with a thread cooperating with a thread 10 complementary to the outlet of the regulator. And a shoulder of the member 341 is also in abutment against a wall parallel to the wall 3114.

  It will be noted that in FIG. 3 the member 341 also passes through the housing 312. It is pointed out that all the wall crossings by this member 341 are made in leaktight manner (in particular by means such as O-rings).

  It is also specified that the member 341 is provided, in its part which in the mounted position is located in the cavity 312, with openings for letting through the secondary gas coming from the regulator and intended to fill this cavity 312.

  FIG. 3 also shows a plug 342, which is intended to cover the fixing member 341 in a leaktight manner.

  In the mounted position, the regulator therefore admits from the secondary gas source a flow at a first pressure, through its inlet 321.

  And the operation of the pressure reducer lowers the secondary gas pressure which is transmitted to the housing 312 via the through orifice 3113.

  It is specified that it is possible to adjust the value of this regulator outlet pressure, by manipulating an adjusting screw 322 of the regulator.

  The housing 312 is produced in the form of a cylindrical cavity 30 in which are engaged a set of elements 33 constituting the secondary inlet valve of the device.

  These elements 33 include: * means for selective passage of gas comprising two elements which are movable relative to one another. These two elements correspond to a hub 331 having a disk-shaped shoulder 3312, and to a plate 332, 5. a part 333 for sealing the motor, intended to establish a perfect seal between the cavity 312 which in operation is filled with secondary gas, and an electric motor M which drives the moving parts of the valve 33, * as well as the various means making it possible to set certain parts in motion (rotation shaft, etc.), or on the contrary to immobilize them.

  The motor M can be a stepping type motor, operating in open loop and with a defined pitch so that 1600 steps correspond to one revolution.

  This motor drives a rotary output shaft (not shown).

  A plate 35 is fixed on the face of the motor which carries said motor output shaft.

  This plate includes: * on the motor side, a circular recess to receive a complementary shoulder of the motor, and thus guarantee the correct positioning of the motor relative to the plate. It is specified that means for fixing the motor and the plate are provided (see the fixing holes 351a 351b and 351c shown on the plate 35), * on the side opposite the motor, that is to say facing the block 25 pneumatic 31, a planar face for receiving in plan-on-plane movement the also planar face of the sealing piece 333 which is opposite. The plate 35 is also provided with fixing holes on the pneumatic block, covering the cavity 312 (three of these four holes, referenced 352a, 352b and 352c, being shown).

  It is specified that the flat surface of the plate 35 which is intended to cooperate in a planar movement on the plane with the surface of the sealing piece 333 is surrounded by a shoulder 350 projecting from the plate 35 towards the cavity 312, shoulder corresponding to the tolerances close to the internal section of the cavity 312.

  This shoulder 350 is intended to allow the watertight fitting 5 of the plate 35 into the cavity 312, when the plate is mounted on the cavity 312.

  To guarantee this seal, an O-ring also surrounds this shoulder.

  Returning to the cooperation of the sealing piece 333 of the plate 35, this cooperation takes place according to a plane-on-plane rotation movement (which will be detailed later).

  In this movement, it is indeed two respective flat surfaces of the part 333 (flat surface surrounding a central cavity 3331) and of the plate 35 (flat surface turned towards the part 333 and 15 surrounded by the shoulder mentioned above) which cooperate.

  This cooperation in plan-on-plan movement makes it possible to ensure total sealing between the part 333 and the plate 35.

  This is valid even when the part 333 is movable relative to the plate 35, in a plane-to-plane rotation movement.

  The plate 35 also has in its center a through recess, for the free passage of the motor output shaft M. This motor output shaft is force fitted into a part 36 which has the two parts in one piece following: * a hollow sleeve for receiving by force fitting at the end of the output shaft of the motor M, so that the part 36 and said shaft are rigidly secured, * one end of parallelepiped shape, facing the sealing part 333.

  When the part 36 is fitted on the output shaft of the motor 30 and the various elements of the device are mounted, the parallelepiped end of this part protrudes above the surface of the plate 35 which faces the part 333 .

  In general, the cross section of this end (which is here represented as square) has a contour having at least one sharp angle.

  And whatever this contour having at least one sharp angle, a cavity 3331, not through, is formed in the thickness of the sealing piece 333, this cavity having a contour corresponding to that of the end of the piece 36.

  Said end of the part 36 is intended to be engaged in the mounted position in this cavity 3331 of the sealing part 333.

  The contours of this end of the part 336 and of the cavity 3331 being corresponding and having at least one sharp angle, the rotation of the motor shaft causes the same rotation of the sealing part 333.

  It is also specified that the end of the part 36 remains free in axial translation relative to the sealing part 333, a clearance being provided for this purpose at the bottom of said cavity.

  Thus, the sealing part 333 is linked in rotation, and free in axial translation, relative to the output shaft of the motor.

  It is specified that by "axial translation" is meant a translation parallel to the axis of rotation of the motor.

  And more precisely, the axial translation is the only degree of freedom that the part 333 has with respect to the output shaft of the motor M. Still with reference to FIG. 3 and progressing towards the cavity 312, the valve 33 comprises as it was said a plate 332.

  This plate can be made of stainless steel.

  This plate has, like the sealing part 333 and the shoulder 3312 of the hub 331, a general shape of a disc.

  It is provided with four fixing holes distributed regularly over its peripheral part, for anchoring by four screws in four corresponding holes of a shoulder at the bottom of the cavity 312.

  In FIG. 3, three of the four holes in the plate 332 are shown, and there can be seen at the bottom of the cavity 312 the shoulder 3121, as well as one of the holes it carries.

  Thus, in the mounted position, the plate 332 is fixed to the bottom of the cavity 312.

  It should be noted, however, that the arrival in the cavity 312 of secondary gas, corresponding to the through orifice 3113, leads even more to the bottom of the cavity 312 (that is to say more to the left and behind in the representation in Figure 3).

  Thus, the plate 332 forms when it is mounted a barrier for the secondary gas supplied to the bottom of the cavity 332.

  This barrier prevents the free diffusion of this secondary gas to the centrifugal compressor, through the through cavity 3122 (which is located above the plate 332 and which communicates with the cavity 3101 for supplying secondary gas to the centrifugal compressor).

  This barrier is waterproof. There is an O-ring arranged to achieve this seal, in association with the shoulder 3121.

  The plate 332 has in its center a recess allowing the free passage of a rotation shaft 334, which is rigidly secured to the hub 331.

  For this purpose, the shaft 334 is force fitted into the center of the hub.

  The other end of this shaft 334 is moreover made integral in rotation with the face of the plate 333 which faces the hub 331.

  However, it should be noted that this other end of the shaft 334 remains free in axial translation relative to the plate 333.

  To this end, as more particularly illustrated in FIG. 4, said other end of the shaft 334 is provided with a transverse slot 25 3340 in which is fitted in the assembled position of the device a pin 3330 engaged transversely in a central and axial recess (not visible) from room 333.

  The cooperation of the slot 3340 and the pin 3330 thus ensures between the shaft 334 and the part 333 a connection with a single degree of freedom, in translation along the axis of rotation of the rotating parts of the device. he

  The plate 332 being fixed in the cavity 312 when the device is mounted, the shaft 334 also remains free to rotate while passing through this plate.

  And this shaft 334 being integral in rotation with the sealing part 5 333, which is itself integral in rotation with the output shaft of the motor, it is understood that the rotation of the motor causes the same rotation not only of the part 333, but also of the hub 331.

  The hub 331 is in turn intended to be received in the bottom of the cavity 312, in a hollow part not visible in the figure.

  The hub 331 is free to rotate in this hollow part.

  The hub 331 has, opposite the plate 332, a planar transverse surface, the plate 332 itself having a planar surface facing the said hub.

  In this way, the contact zone between the hub 331 and the plate 332 is defined by these two planar faces, which are able to cooperate in plan-on-plane movement.

  In this regard, the hub 331 is made of a material such as Teflon.

  The hub 331 and the plate 332 constitute the means 20 for the selective passage of gas from the valve 33.

  The hub thus has an opening 3311, and the plate also has an opening 3321.

  These two openings can be brought totally or partially opposite one another, by the play of the rotation of the hub 25 driven by the rotation of the motor (which is itself controlled by the control means of the device).

  It is also possible to place the valve in the closed position, the overlap between the two openings then being nonexistent.

  In order to guarantee the tightness of the contact between the hub 331 and the plate 332, and to further guarantee that the opening by means of selective passage of gas thus formed takes place regularly, the hub 331 is permanently stressed. pressing against the corresponding surface of the plate 332.

  For this purpose, a compression spring (not shown for clarity) is' arranged between the bottom of the cavity 312 and the rear face of the shoulder 3312 of the hub.

  This spring thus permanently applies a compression stress on the hub 331, towards the plate 332.

  In this way, secondary gas leaks between the hub 331 and the plate 332 are prevented.

  In addition, it is guaranteed that the only passage of secondary gas through the valve 33 corresponds well to the controlled correspondence of the respective openings of the hub 331 and of the plate 332, this correspondence being controlled with precision by controlling the rotation of the engine M which drives the hub.

  The hub 331 and the plate 332 thus make it possible to constitute a “flat” valve, by cooperating in a plane-on-plane rotary sliding movement.

  The spring associated with the hub 331 thus contributes, in association with the flat configuration of the valve 33, to perform the following functions: * press said two elements one on the other in order to prevent leakage of secondary gas in the contact zone of said two elements, * and guarantee that the opening of the selective gas passage means is done regularly.

  And the fact that the compression stress of the spring is exerted continuously also makes it possible to perform a third function: in the absence of any constraint, the elements of the selective gas passage means remain in position, so that it does not It is not necessary to constantly apply a constraint to maintain said means for selective passage of gas in a given position.

  This constitutes an important advantage compared to the valves usually used in this type of device, since such known valves must be permanently stressed in order to maintain a given open position.

  In the present case, on the contrary, in the absence of any external stress, the hub 331 remains in its position, and the valve 33 continuously ensures the passage of secondary gas according to the desired instruction, without it being necessary to actuate the engine M. This results in simplicity of operation and significant energy savings.

  Returning to the openings 3311 and 3321 of the hub and of the plate, each of these two openings is included in a respective region of the hub of the plate which generally extends in a portion of a circle around the axis of rotation of the hub.

  The opening 3311 of the hub has a constant width.

  The width of the opening 3321 of the plate 332 is, on the contrary, variable.

  It is specified that the reverse is possible (opening 3321 of constant width, and opening 3311 of variable width).

  In any event, the opening of variable width can see its width in a linear manner when one traverses this opening in an orthoradial direction.

  And the Applicant has determined that an opening whose width varied from a minimum value of approximately 0.3 mm to a maximum value of approximately 0.6 mm was well suited to the operation of the device.

  In practice, such a valve 33 makes it possible to cover a wide range 25 of flow rates (for example from 0.5 to 150 liters / minute).

  The fact that the opening of the plate 332 has a variable width also allows an operation in which, when an opening of the valve is ordered, the narrow part of this opening is the first to be located opposite the opening 3311 from hub 331.

  As a result, when one wishes to control low secondary gas flow rates, one has a very good degree of control.

  When the opening of the valve 33 is continued, the cross-section of the secondary gas increases more rapidly, due to the gradual widening of the opening 3321. It is then possible to quickly have access to higher flow rates.

  The device also includes a second spring (also not shown for the sake of clarity).

  This second spring is also a compression spring, this time interposed between the plate 332 and the sealing part 333.

  This compression spring is thus supported on the two opposite faces of the plate 332 and of the sealing part 333, and keeps these two parts apart.

  More specifically, the role of this spring is to permanently compress the sealing part 333 against the plate 35, to help ensure the tightness of the contact between these two elements even when they are in movement relative to one another. to the other.

  The part 333, in association with this spring, thus makes it possible to fulfill the following two functions: e transmitting the torque of the motor to the hub (thanks to the cooperation of its cavity 3331 with the end of the part 36), * guarantee sealing the engine with respect to the cavity containing the means for selective passage of gas.

  During the rotation of the sealing part 333, this part performs a plane-on-plane rotary sliding movement on the surface facing the shoulder 350 of the plate 35.

  And this movement takes place while guaranteeing a total seal between the part of the cavity 312 located between the plate 332 and the sealing piece 333 on the one hand, and the motor M on the other hand.

  This seal is guaranteed by the permanent compression of the part 333 on the surface of the shoulder 350 of the plate 35 (and also by the fact that the surface of the part 333 completely covers the surface in contact with the plate 35, thus only by the presence of the O-ring which surrounds this shoulder).

  The through cavity 3122 is located when the valve is mounted between the plate 332 and the sealing piece 333, so that the oxygen admitted through the cooperating openings of the hub 331 and of the plate 332 is directed exclusively to the centrifugal compressor .

  The device according to the invention thus makes it possible to control with great precision the dosage of a secondary gas which it is desired to inject into a respiratory gas from a source such as a centrifugal compressor.

  The valve 33 can be controlled, through the operation of the engine M, in proportion to a valve 10 located on the inspiration pipe of the device, which regulates the passage of the enriched respiratory gas towards the patient.

  It will be noted that the configuration of the device according to the invention also makes it possible to completely guarantee the leakage of secondary gas: * at the level of the selective gas passage means, which offers very high accuracy in controlling the dosage, * and at the level of the engine M, which makes it possible to avoid drawbacks such as oxidation with a secondary gas consisting of oxygen of the grease of rotating parts of the engine, etc. In the case of a device fitted with bearings as is known, these advantages would not have been achieved.

  Finally, it is specified that the sealing piece 333 is provided with a small recess 3332 to receive a forced fitting rod, directed towards the bottom of the cavity 312.

  This rod constitutes a visual reference which is seen by an optical sensor 25 housed in the bottom of the cavity 312 (and not shown).

  This sensor and this pin thus constitute means making it possible to index the angular position of the rotary elements of the valve 33.

  It should be noted that FIG. 3 still makes it possible to view the hole 3123 through which the optical sensor is engaged in the cavity 312.

  The motor M operating in open loop, the detection of the reference position of the pin makes it possible to calibrate the operation of the device.

Claims (21)

  1. Breathing aid device comprising a source of pressurized gas capable of generating a flow of respiratory gas intended for a patient, and a secondary intake valve (33) connected to said source for selective intake. a secondary gas intended to enrich said respiratory gas, the means for selective passage of gas from said valve comprising two elements (331, 332) movable with respect to one another to selectively match the openings of the two elements, characterized in that the movement of said two elements of the selective gas passage means is a plane-on-plane movement and compression means are provided to help achieve the following functions: pressing said two elements one on the other other in order to prevent secondary gas leaks in the contact zone of said two elements, * and to guarantee that the opening of the selective gas passage means takes place in a r gulière.   2. Device according to the preceding claim, characterized in that said plane-on-plane movement is a plane-on-plane rotational movement.   3. Device according to one of the preceding claims, characterized in that said compression means for pressing said two elements one on the other apply a compression stress 30 permanently, so that said compression means perform a third function: * in the absence of any constraint, the elements of the selective gas passage means remain in position, so that it is not necessary to permanently apply a constraint to maintain said selective gas passage means in a given position.   4. Device according to one of the preceding claims, that said two elements comprise: has a hub capable of being rotated by having a planar transverse surface, * as well as a fixed plate also having one of the two planar surfaces of the hub and from the plate to the contact area between the hub and the plate.   characterized by a motor and corresponding flat surface 5. Device according to the preceding claim, characterized in that the hub and the plate each have a respective opening, the two openings being included in respective regions of the hub and the plate which generally extend along a portion of a circle around the axis of rotation of the hub. 20 6. Device according to the preceding claim, characterized in that the width of an opening of one of the two elements of the selective gas passage means is substantially constant, while the width of the opening of the other element of the means selective gas passage is variable.   7. Device according to the preceding claim, characterized in that said variable width varies linearly.   8. Device according to one of the two preceding claims, characterized in that said variable width varies from approximately 0.3 mm to approximately 0.6 mm.   9. Device according to one of the three preceding claims, characterized in that the plate carries the opening of variable width and the hub carries the opening of constant width.   10. Device according to one of the seven preceding claims, characterized in that said compression means for pressing the hub on the plate comprise a spring which permanently biases the hub in compression on the plate.   11. Device according to one of the eight preceding claims, characterized in that the hub is made of Teflon (registered trademark).   12. Device according to one of the nine preceding claims, characterized in that the device comprises a motor for driving moving parts and an engine sealing part is provided at the engine outlet, which fulfills the following two functions: * Transmit the torque from the engine to the hub, ò Guarantee the tightness of the engine relative to the cavity containing the selective gas passage means. 25 13. Device according to the preceding claim, characterized in that said sealing part is linked in rotation, and free in axial translation, relative to the output shaft of the motor.   14. Device according to the preceding claim, characterized in that: said sealing part comprises, facing the motor, a cavity whose contour has at least one sharp angle, and ò a part rigidly secured to the motor output shaft is engaged in said cavity,> the end of said part rigidly secured to the motor output shaft having a contour substantially corresponding to that of said cavity of the sealing part, to drive it in rotation,> said end of the part rigidly secured to the output shaft of the motor also remaining free in axial translation relative to the sealing part, a clearance being provided for this purpose at the bottom of the cavity of said sealing part.   15. Device according to one of the three preceding claims, characterized in that said sealing part is integral in rotation with the rotation shaft driving the hub, but has a degree of freedom with respect to this shaft. axial translation.   16.Device according to one of the four preceding claims, characterized in that said sealing part has a flat surface opposite another flat surface, which is it integral with the engine and compression means are provided for permanently press the two surfaces together.   17. Device according to the preceding claim, characterized in that when said sealing part is driven in rotation by the torque of the motor, this rotation is carried out according to a plane movement on plane of the planar surface of the part sealing and the plane surface integral with the engine. 30 18. Device according to one of the two preceding claims, characterized in that said compression means for pressing the surface of the sealing part and the surface integral with the motor comprise a spring placed between said plate and said sealing part.   19. Device according to one of the seven preceding claims, characterized in that the said sealing part is made of Teflon (registered trademark).   20. Device according to one of the preceding claims, characterized in that the device comprises, upstream of the means for selective passage of gas and downstream of a source of secondary gas, a regulator.   21. Device according to the preceding claim, characterized in that said regulator is associated with a leak pipe, and means are provided for recovering the secondary gas in said leak pipe and injecting it into the source of respiratory gas under pressure.