[0001] The present invention refers to an air demand-valve device of a compressed-air breathing
apparatus (for open circuit compressed-air), that is apt for supplying air, at a prefixed
pressure-slightly higher than atmospheric pressure, into an ambient (normally comprising
an inner cavity with an anti-gas mask) of said breathing apparatus, which must result
as being structurally very simple, reliable, and which must allow for a very high
delivery-flow of air into the above-said ambient, and with moreover, maintaining substantially
constant the ambiental-pressure itself.
[0002] A demand-valve device of the type to which the device of the invention belongs, usually
comprises a chamber that communicates with a source-of-air having a mean pressure-i.e.
comprised between 2 and 10 Bar., through a first-entry-gate, and with the above-said
ambient, through a second-exit-gate. The passage-opening, through the first-entry-gate
is controlled by intercepting-means comprising a blocking-element mechanically connected
to a deformable membrane apt for defining a surface of said chamber, in such a way
that-following the shifting of the membrane, the blocking-element is also shifted,
for thus controlling the passage-opening. With said constructive disposition, whenever-following
a pressure decrease that is verified in said ambient due to the effects of inhalation
on the part of the user of the breathing apparatus, the above-said deformable membrane
shifts-and the opening is effectuated of the above-mentioned blocking-element, in
such a way as to allow a sufficient admission of the air- flow into said chamber for
restoring the original pressure conditions once again.
[0003] The complex-comprised by the above-said membrane and by the kinematic chain that
connects it to the above-mentioned blocking-element, substantially constitutes a transducer
which is apt for measuring the pressure existing inside the chamber, and for controlling-as
a function of said pressure, the shifting of the blocking-element, for feeding appropriate
quantities of air into the chamber.
[0004] Under the conditions described till now, the pressure existing downstream of the
blocking-element is, in static terms, equal to atmospheric-pressure, and it decreases
slightly during the act of inhalation-with putting the interior of the mask under
vacuum. The addition of a spring--having suitable mechanical characteristics, that
presses against the membrane from the outside, or else, some other device that performs
the same task-allows for obtaining, in static terms, a slight overpressure, with respect
to the surrounding atmosphere, downstream of the blocking-element-which, during any
actual inhalation, decreases and can also change signs.
[0005] However, the air demand-valve devices of the type described, present certain drawbacks.
[0006] First and foremost, when particularly high air delivery-flows are required-as a consequence
of increased and repeated inhalation on the part of the user, the air pressure existing
inside said chamber-and hence, also in the ambient that communicates with the chamber
itself, decreases sensibly with respect to the initial pressure. In such a situation,
the respiratory efforts of the user himself, also increase-owing to the greater difficulty
had in inhaling air. Moreover, the pressure inside the mask decreases sensibly, with
assuming-even in instances of the apparatus also being endowed with an overpressure
spring, lower values as compared to those of atmospheric-pressure.
[0007] As a consequence of this, with the air demand-valve devices of the type described,
the user is required to make non-negligible breathing efforts-and particularly, whenever
greater air delivery-flows are necessary. Therefore, the specified conditions of safety
cannot be realized--because, in the proximity of the sealing-surface, inside the mask,
the pressure can notably decrease to below that of the outside atmosphere, with thus
involving risks of gases and/or vapours entering-in from the polluted surrounding
ambient where the user happens to be.
[0008] The above-mentioned drawbacks depend substantially upon the fact that-apart from
the atmospheric-pressure and the pressure existing inside the above-mentioned chamber,
there also act, on the above-said membrane, the fluodynamic effects of the air-jet
that enters into said chamber, and which-owing to the repeated surface-reflections
taking place, can affect the membrane itself.
[0009] Said fluodynamic actions can have either a positive or a negative sign-and can vary
considerably, besides irregularly, as a function of the air-flow delivered by the
device, with also changing signs, and with resulting as being strongly resistent to
static action in instances of any greater air-flows. Therefore, for obtaining these
actions, a vacuum is often required-and hence, an effort on user's part, that proves
to be much greater than what is foreseen by a calculation of static balance.
[0010] For example, accorng to US-A-4253455 a demand breathing apparatus comprises in a
cylindrical chamber, an inlet valve, a diaphragm controlling the inlet valve, an exit-gate
adapted for airtight communication with the breathing function of a user. The exit
gate is disposed with the axis orthogonal to the diaphragm, near the inlet valve.
[0011] In this device, owing the fluodynamics effects of the air-jet entering into the chamber
and affecting directly the diaphragm, the functioning is irregular.
[0012] For overcoming the above cited drawback is known according to US-A-3626974 a demand
regulator comprising in a cylindrical chamber an inlet valve, a diaphragm controlling
the inlet valve, an exit-gate for the user's mouth.
[0013] The exit-gate has axis orthogonal to the diaphragm, near the inlet valve.
[0014] Further, the device comprises a curve conduc
- tor between the inlet and the exit-gate for eliminating any direct contact of the
dynamic air- flow upon the surface of the diaphragm itself, for suppressing in this
way, the above-described fluodynamic effect.
[0015] Nevertheless, this device is of a complex construction, owing to the need of a tubular
conduit and further is not apt for supplying air that is sensibly constant.
[0016] The aim of the present invention is to realize an air demand-valve device for a compressed-air
breathing apparatus of the previously indicated type, but which will be in a condition
to eliminate the above-mentioned drawbacks, and which, in particular, will be apt
for supplying air-that is sensibly constant and of a better quality than the air of
the surrounding atmosphere, into the ambient of the breathing apparatus, and even
in those instances when the air-delivery flows may be considerably increased.
[0017] On the basis of the present invention, there has been realized an air demand valve
device for a compressed-air breathing apparatus for distributing air of a predetermined
pressure into an ambient of said compressed air breathing apparatus, the demand valve
device comprising
a substantially cylindrical chamber comprising parallel upper and lower end walls;
a bellows fixed with its upper end surface to said upper end wall;
holes in said upper end wall leading from outside the chamber to the interior of said
bellows;
an air entry port on the lateral surface of the chamber comprising a first bore, formed
by a first substantially cylindrical hole and a second hole delimited by a conical
surface, the passage of air through said first bore being controlled by intercepting
means comprising a blocking element bearing mechanically against the lower end surface
of said bellows such that moving of said bellows raises moving of said blocking element,
the axis of said first bore being inclined at a first angle with respect to said end
walls of the chamber;
an exit port for feeding said air into said ambient, said exit port being disposed
on the lower end wall of the chamber and comprising a second bore, the axis of said
second bore being inclined at a second angle with respect to the axis of said chamber,
and the axes of said first and second bores lying in the same diametrical plane of
the chamber.
[0018] Said first angle is opportunely comprised between 15° and 25°, and said second angle
is comprised between 5° and 15°. Moreover, for convenience sake, the distance between
said axis of said lateral surface, and the point-of-intersection of said axis of the
second gate with the plane that frontally delimits the gate itself, is comprised between
20% and 35% of the diameter of said chamber.
[0019] For having a better comprehension of the device of the present invention, there will
now be given, solely by way of example, the description of one particular form of
realization with making reference to the attached drawings, whereby:
-Figure 1 represents a vertical section of the air demand-valve device of the invention;
-Figure 2 represents a plane view, partially in section, of the device of Figure 1;
Figures 3 and 4 represent sections-of a part of the air demand-valve device of Figure
1, in two different operative positions;
-Figure 5 represents certain diagrams apt for illustrating the curve of the air-pressure
delivered, as a function of the air-flow capacity itself, that is encountered in the
device of the invention, as well as in the devices of the prior art of the same type.
[0020] First and foremost, referring to Figure 1, the air demand-valve device of the invention-indicated
in its complex whole with the reference numeral 1, is apt for being interposed between
a compressed-air feeding breathing-tube 2 and an ambient (not shown) comprised, for
example, by the space inside an anti-gas mask, into which breathable air has to be
fed.
[0021] The device comprises a substantially cylindrical chamber 3, delimited by a lateral-wall
4 and a pair of substantially flat base-walls 5 and 6. Inside the chamber 3, there
is disposed a membrane 7 which comprises a substantially flat base-wall 8 and a lateral-wall
9, that presents a plurality of corrugations apt for rendering said membrane shaped
as a bellows deformable in the direction of the axis of the chamber 3. With the wall
5, said membrane defines another chamber 10, which communicates with the atmosphere
through one or several holes 11, made in the wall 5. For convenience sake, the device
can comprise a spring 7a, disposed inside the membrane 7 and predisposed for exercising
a prefixed axial-force on the flat wall 8. The device comprises moreover, a first
entry-gate 14-that is apt for putting the tube 2 into communication with the chamber
3, and which is made substantially in the lateral-wall 4 which delimits said chamber,
and a second exit-gate 15-for putting the latter into communication with the internal
ambient of the mask, and which is made in the base-wall 6 that also delimits the chamber
itself.
[0022] Inside the entry-gate 14, there is disposed a bush 16, provided with a pair of axial
holes 17 and 18-of which the first is cylindrical and the second conical, as well
as with a seat 19 having a substantially annular form, apt for housing the blocking-element
20 that is normally held against said seat by means of a spring 21-interposed in-
between the latter and another bush 22 that is screwed into a threaded-hole made inside
the entry-gate 14-as is clearly visible in Figure 1.
[0023] The blocking-element 20 is made solidal with a rod 23 that goes through the holes
17 and 18, and whose extremity is provided with a stylus 24 apt for collaborating
with the surface of the wall 8 of the membrane 9.
[0024] On the basis of the invention, the axis of the first entry-gate 14-indicated with
a, in Figure 1, forms a first angle a with the base-surfaces that delimit the chamber
23 and, in particular, with the surface of the flat wall 8 of the deformable membrane
9. Moreover, the axis of the second exit-gate 15, indicated with a
2 in Fig. 1, forms a second angle β, with the axis a
o of the chamber itself; the two axes, a
1 and a
2, lie substantially in the same diametrical plane of the chamber 3-which coincides
with that in the drawing of Fig. 1.
[0025] For the purpose of achieving the aims that shall be indicated further on in the text,
the angles a and (3 are comprised respectively between 15° and 25° and between 5°
and 15°. Moreover, the distance-between the axis a
o of the chamber 13 and the intersection point C of the axis a
2 of the exit-gate 15 with the plane that frontally delimits the gate itself (and which
has been indicated with e in Figure 1), is comprised between 20% and 35% of the diameter
of said chamber. In this manner, the opening of the outlet 25 of the exit-gate 15,
results as being substantially eccentric with respect to the axis a
o of the chamber 3-as clearly results in Figure 1.
[0026] Inside the chamber 3, and in the vicinity of the lead-in of the second gate 15, there
is disposed a substantially flat wall 29. The plane of said wall is substantially
parallel to that of the axis a
o and perpendicular to the plane that contains the axes a
1 and a
2 respectively, of the gates 14 and 15. Moreover, the said wall comprises, for convenience
sake, a rib 30, having the function of conveying the airflow, as well as that of acting
as a stiffening.
[0027] Next, the half-opening of the conical surface-that delimits the second hole 18, downstream
of the blocking-element 20, is comprised between 16° and 18°. The ratio, between the
axial length of the first and second hole 17 and 18, is comprised between 0.85 and
0.45; whereas, for convenience sake, the axial lengths of the holes themselves, are
comprised between 4 and 6 mm and between 7 and 9 millimeters respectively.
[0028] To end with, the ratio between the diameter of the first hole 17 and its axial length,
is comprised between 0.85 and 1.32, and-for convenience sake, the diameter of the
hole itself, is comprised between 5.1 and 5.3 mm.
[0029] In practical usage tests, the air demand-valve device described, has-quite surprisingly,
proved to function in a very satisfactory way. It has been endeavoured to give a rational
explanation, with the following considerations, which must be taken as being qualitative-since
the complexity of the forms, and of the surface reflections in particular, that are
for the most part curved, impede obtaining, with any precise mathematical calculus,
an exact prevision of the behaviour of the device itself.
[0030] When it is inserted into the circuit of the self- breathing apparatus, there exists
inside of chamber 3-between the compressed-air feeding tube 2 and the mask of the
compressed-air breathing apparatus itself, and under normal functioning conditions
of the device, a pressure that is slightly higher than atmospheric-pressure-for example:
a pressure that has from 30-40 mm of water-column height above said pressure. As is
already known, such a pressure inside the chamber 3-and hence, in the ambient of the
compressed-air breathing-apparatus into which breathable air must be introduced, offers
a greater guarantee of safety for the user-since, under such conditions, there is
impeded any infiltration of gases or vapours from the polluted surrounding atmosphere
wherein the user happens to be.
[0031] If it is supposed that the spring 7a is absent (a functioning condition that can
be defined as "negative pressure") the membrane 9 becomes disposed in a balanced position,
depending upon the pressure value that exists inside the chamber 10-which acts on
one of the surfaces of the wall 8, and the above-said pressure that exists in the
chamber 3-which acts upon the other surface of the wall itself. When the pressure
inside the chamber 3 is reduced, even to a modest extent--following an inhalation,
said "balanced condition' becomes changed and the wall 8 of said membrane, shifts
towards the stylus 24, determining the rotation of the rod 23 substantially in the
plane of the drawing of Figure 1, for controlling the opening of the blocking-element
20-which substantially assumes the configuration illustrated in Figure 3, whereby
it leans just on a very restricted zone of the housing 19, with leaving free a part
having prefixed dimensions, through which there is established an air-flow entry into
the chamber 3.
[0032] The addition of a spring such as 7a-having suitable mechanical characteristics, which
presses against the wall 8 of the membrane 7 (or some other such device for carrying
out the same task), allows for obtaining-under static conditions, a slight overpressure,
with respect to the surrounding atmosphere, downstream of the blocking-element-and
hence, inside of the mask; which said overpressure becomes reduced during the act
of inhalation and can also change its sign. This functioning condition can also be
defined as being "positive pressures".
[0033] The above-said air-flow that, given the pressure conditions inside chamber 3 and
inside tube 2, realizes a true and proper supersonic expansion-enters into said chamber
through a plurality of axial deviations that are comparable, for simplicity sake,
to reflections on the walls of the holes 17 and 14-for example; according to the succession
of reflections indicated with the broken-line of Figure 3. As can clearly be seen
from said broken-line, the above-said flow follows a trajectory comprised by a succession
of rectilineal tracts, as a conseqeuence of these said reflections, which do not interfere
with the flat wall 8 of the membrane 9. In particular, the trajectory tract indicated
with to, by which the above-said flow passes through chamber 3-substantially in the
traversal direction, has a slightly inclined direction with respect to the plane of
the wall, in such a sense as to draw away from it, so as to strike further surfaces
inside of the chamber 3 and to come out from the exit-opening 15, through the means
of a series of further reflections.
[0034] A trajectory of this tyqe, i.e. comprising a succession trajectory-tracts-none of
which strike the wall 8 of the membrane 9, is the result of the form of the disposition
of the various parts of the device and, in particular, of the relative position of
the axes a
1 and a
2 of the gates 14 and 15, defined by the angles a and β, of the presence of the eccentricity
presented by the exit-gate 25 of the gate 15 with respect to the axis a
o (eccentricity s), as wsll as by the form and the dimensions, defined previously,
for the holes 14 and 17, downstream of the blocking-element 20.
[0035] It has been verified that, whenever the previously mentioned geometrical parameters
are selected from the indicated ranges of values, the favourable condition-for realizing
trajectories of air-flows from the entry-gate 14 to the exit-gate 15, with trajectories
that never interfere with the wall 8 of the membrane 9-is obtained not only for a
particular opening angle of the blocking-element 20, but substantially for opening
angles which go from zero to a maximum angle-to which correspond considerably high
air-flow entries into the chamber 3, that are necessary for feeding breathable air
for the user, with continuity, even under the most unfavourable operative conditions.
In Figs. 3 and 4, there have been indicated two different configurations of the membrane
9, to which correspond two diverse opening-angles of the blocking-element 20. There
are also shown herein, the trajectories of the air-flows which are obtained presumably,
in these two instances. As can be clearly seen, none of these comprise flow-tracts
that strike the membrane 8.
[0036] It has also been verified that the first wall 29, inserted into the first position
indicated inside of the chamber 3, also contributes for conveying the air-flow towards
the exit-gate 15. Moreover, said wall can constitute the end-stop limiter, for the
shifting-movement of the wall 8 of the membrane 9.
[0037] Therefore, it is evident that, with the air demand-valve device of the invention,
any negative fluodynamic actions on the membrane 8 generated by the air-jet entering
chamber 3, is prevented, i.e. those actions which tend to take membrane towards the
at-rest conditions corresponding to the null flow-and without even needing to have
recourse to any costly and complex mechanisms for removing the membrane from the effects
of said air-flow; but instead, it is had that, through the effects of the air-flow
divergence from the membrane, as can be seen in Figures 3 and 4, the action of said
membrane on the blocking-element 20 is amplified in such a way as to achieve a minimum
lowering of the pressure (or of the overpressures) existing inside the mask for the
entire field of instantaneous respiratory intensity, as necessitated by human physiology
(upper limit about 300 I/min). Under these conditions, an air- flow having a very
high capacity can be controlled, without any particular respiratory efforts on the
user's part. It has been found that, under particular functioning conditions of the
device, involving trajectory tracts that tend to draw away from the membrane 8 (as
was shown in the instance of Figures 3 and 4), there is even had a suction action
upon the membrane, which can favour the opening of the blocking-element whenever very
high air-flows must be supplied.
[0038] In Fig. 5 there is indicated, with the curve A, the development of the pressure inside
the chamber 3 as a function of the air-flows supplies. As can be seen from said curve,
inside of the chamber 3 there exists a substantially constant pressure (no matter
what the flow of air supplied may be) comprised within the range that concerns those
applications to which the air demand-valve device of the invention is intended. Moreover,
the above-said pressure tends to become lower, only in correspondence of the upper
value limit of the above-said range of values-without however, creating a depression
inside the mask to which the air- breathing device itself is connected.
[0039] In the same Figure 5, there are represented, with the curves B and C, the pressure-flow
characteristics, for other known air breathing- devices of the type described. As
can be seen, not only is a sensible reduction of pressure had-as soon as the aiflow
introduced by the device tends to increase, but said pressure can become already negative
because of the flow- values comprised within the range that concerns the viewpoint
of practical applications.
[0040] In said Figure, the scales given on the left-hand side, relate to a function-configuration
with "positive pressures" (obtained through the presence of the spring 7a); whereas
those given on the right-hand side, relate to a functioning-configuration with "negative
pressures" (obtained without the spring 7a).
[0041] The air demand-valve device of the invention-apart from its presenting the favourable
properties described previously, results as also being constructively very simple-because
of its being constituted of a only a few elements that can easily be constructed and
which do not require any restricted working tolerances. Hence, this device results
as also being very reliable-seeing that it maintains, during the course of its usage,
the favourable characteristics that have been previously described.
1. Air demand valve device (1) for a compressed-air breathing apparatus for distributing
air of a predetermined pressure into an ambient of said compressed air breathing apparatus,
the demand valve device comprising
a substantially cylindrical chamber (3) comprising parallel upper (5) and lower end
walls (6);
a bellows (7) fixed with its upper end surface to said upper end wall;
holes (11) in said upper end wall (5) leading from outside the chamber to the interior
of said bellows;
an air entry port (14) on the lateral surface of the chamber comprising a first bore,
formed by a first substantially cylindrical hole (17) and a second hole (18) delimited
by a conical surface, the passage of air through said first bore being controlled
by intercepting means comprising a blocking element (20) bearing mechanically against
the lower end surface (8) of said bellows such that moving of said bellows raises
moving of said blocking element, the axis (a1) of said first bore being inclined at
a first angle a with respect to said end walls of the chamber;
an exit port (15) for feeding said air into said ambient, said exit port being disposed
on the lower end wall (5) of the chamber and comprising a second bore, the axis (a2)
of said second bore being inclined at a second angle P with respect to the axis (ao) of said chamber, and the axes of said first and second bores lying in the same diametrical
plane of the chamber.
2. Air demand-valve device, according to Claim 1, characterized by the fact that said
first angle is comprised between 15° and 25° and said second angle is comprised between
5° and 15°.
3. Air demand-valve device, according to Claim 1 or 2, characterized by the fact that
the distance (e), between said axis (ao) of said lateral surface and the point-of-intersection (C) of said second-gate's
axis with the plane that frontally delimits the gate itself, is comprised between
20% and 35% of the diameter of said chamber.
4. Air demand-valve device, according to one of the previous Claims, characterized
by the fact that it comprises a diaphragm, disposed inside said chamber, comprising
at least a flat wall (29) disposed in the vicinity of the mouth of said second-gate
and on a plane that is substantially parallel to said axis (ao) of said lateral surface and perpendicular to said plane that contains the axes of
the gates (ai, a2).
5. Air demand-valve device, according to one of the previous Claims, wherein, downstream
of said blocking-element (20), said gate comprises a first, substantially cylindrical
hole (17) and a second hole (18) delimited by a conical surface, characterized by
the fact that the half-opening of said conical surface is comprised between 16° and
18°.
6. Air demand-valve device, according to Claim 5, characterized by the fact that the
ratio between the axial length of said first and second holes, is comprised between
0.85 and 0.45.
7. Air demand-valve device, according to Claim 4 or 5, characterized by the fact that
the axial lengths, of said first and said second hole, are comprised respectively,
between 4 and 6 mm. and between 7 and 9 mm.
8. Air demand-valve device, according to one of the Claims from 5 to 7, characterized
by the fact that the ratio-between the diameter of said first hole and its axial length,
is comprised between 0.85 and 1.32.
9. Air demand-valve device, according to Claim 8, characterized by the fact that the
diameter of said first hole, is comprised between 5.1 and 5.3 mm.
10. Device, according to Claim 1, characterized by the fact that said bellows (7)
comprises a substantially flat and indeformable base-surface (8), apt for defining
said base-surface of said chamber, and a deformable lateral surface (9) provided with
a plurality of corrugations.
1. Sofort-Luftventilvorrichtung (1) für einen Druckluftatmungsapparat zum Verteilen
von Luft eines vorbestimmten Druckes in einer Umgebung oder einen Raum des Druckluftatmungsapparates,
wobei die Sofortventilvorrichtung umfaßt
eine im wesentlichen zylindrische Kammer (3), die eine obere Endwand (5) und eine
dazu parallel untere Endwand (6), hat,
einen Balgen (7), der mit seiner oberen Endfläche an der oberen Endwand befestigt
ist,
Löcher (11) in der oberen Endwand (5), die von dem Raum außerhalb der Kammer zum Inneren
des Balgens führen,
eine Lufteintrittsöffnung (14), an der Seitenfläche der Kammer, umfassend eine erste
Bohrung, die durch ein erstes im wesentlichen zylindrisches Lock (17) gebildet ist,
und ein zweites Loch (18), welches von einer konischen Fläche begrenzt ist, wobei
der Durchtritt von Luft durch die erste Bohrung gesteuert ist durch eine Unterbrechungseinrichtung,
die ein Blockierelement (20) aufweist, welches sich mechanisch gegen die untere Endfläche
(8) des Balgens legt derart, daß durch Bewegung des Balgens Bewegung des Blockierelementes
hervorgerufen wird, und wobei die Achse (a1) der ersten Bohrung in einem ersten Winkel
a mit Bezug auf die Endwände der Kammer schräg verläuft,
eine Austrittsöffnung (15) zum Zuführen von Luft in die Umgebung, wobei die Austrittsöffnung
an der unteren Endwand (5) der Kammer angeordnet ist und eine zweite Bohrung aufweist,
deren Achse (a2) in einem zweiten Winkel β mit Bezug auf die Achse (ao) der Kammer schräg liegt, und die Achsen der ersten und der zweiten Bohrung in der
gleichen Diametralebene der Kammer liegen.
2. Sofort-Luftventilvorrichtung nach Anspruch 1, dadurch gekennzeichnet, daß der erste
Winkel zwischen 15° und 25°, und der zweite Winkel zwischen 5° und 15° liegt.
3. Sofort-Luftventilvorrichtung nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß
der Abstand (s) zwischen der Achse (ao) der Seitenfläche und dem Schnittpunkt (C) der Achse des zweiten Tores mit der Ebene,
welche das Tor frontal begrenzt, zwischen 20% und 35% des Durchmessers der Kammer
beträgt.
4. Sofort-Luftventilvorrichtung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet,
daß sie eine Membran aufweist, die in der Kammer angeordnet ist und wenigstens eine
ebene Wand (29) hat, die in der Nähe des Mundes bzw. der Öffnung des zweiten Tores
und in einer Ebene angeordnet ist, die im wesentlichen parallel zu der Achse (ao) der Seitenfläche und rechtwinkelig zu der Ebene liegt, welche die Achsen der Tore
(ai, a2) enthält.
5. Sofort-Luftventilvorrichtung nach einem der vorhergehenden Ansprüche, in welcher
stromabwärts des Blockierelementes (20) das Tor ein erstes im wesentlichen zylindrisches
Loch (17) und ein zweites Loch (18) aufweist, welches durch eine konische Fläche begrenzt
ist, dadurch gekennzeichnet, daß die Halböffnung der konischen Fläche zwischen 16°
und 18° liegt.
6. Sofort-Luftventilvorrichtung nach Anspruch 5, dadurch gekennzeichnet, daß das Verhältnis
zwischen der axialen Länge des ersten und des zweiten Loches zwischen 0,85 und 0,45
liegt.
7. Sofort-Luftventilvorrichtung nach Anspruch 4 oder 5, dadurch gekennzeichnet, daß
die axiale Länge des ersten und des zweiten Loches zwischen 4 und 6 mm bzw. zwischen
7 und 9 mm liegt.
8. Sofort-Luftventilvorrichtung nach einem der Ansprüche 5 bis 7, dadurch gekennzeichnet,
daß das Verhältnis zwischen dem Durchmesser des ersten Loches und seiner axialen Länge
zwischen 0,85 und 1,32 liegt.
9. Sofort-Luftventilvorrichtung nach Anspruch 8, dadurch gekennzeichnet, daß der Durchmesser
des ersten Loches zwischen 5,1 und 5,3 mm liegt.
10. Vorrichtung nach Anspruch 1, dadurch gekennzeichnet, daß der Balgen (7) eine im
wesentliche ebene und unverformbare Basisfläche (8), welche die Basisfläche der Kammer
bilden kann, und eine verformbare Seitenfläche (9) aufweist, die mit einer Mehrzahl
von Wellungen versehen ist.
1. Dispositif à valve de demande d'air (1) pour un appareil respiratoire à air comprimé
servant à distribuer de l'air à une pression prédéterminée dans un volume ambiant
dudit appareil respiratoire à air comprimé, le dispositif à valve de demande d'air
comprenant:
-une chambre (3) sensiblement cylindrique comprenant des parois extrêmes supérieure
(5) et inférieure (6) parallèles;
-un soufflet (7) fixé par surface extrême supérieure sur ladite paroi extrême supérieure;
-des trous (11) ménagés dans ladite paroi extrême supérieure (5) et reliant l'extérieur
de la chambre à l'intérieur dudit soufflet;
-un conduit d'entrée d'air (14) prévu sur la surface latérale de la chambre et comprenant
un premier passage, formé par un premier trou (17) sensiblement cylindrique et un
second trou (18) délimité par une surface conique, l'écoulement de l'air dans ledit
premier passage étant commandé par un moyen d'interception comprenant un élément de
blocage (20) s'appuyant mécaniquement contre la surface extrême inférieure (8) dudit
soufflet, de telle sorte qu'un mouvement dudit soufflet fasse déplacer ledit élément
de blocage, l'axe (a1 ) dudit premier passage étant incliné d'un premier angle (a)
par rapport auxdites parois extrêmes de la chambre;
-un conduit de sortie (15) pour canaliser ledit air jusque dans ledit volume ambiant,
ledit conduit de sortie étant disposé sur la paroi extrême inférieure (5) de la chambre
et comprenant un second passage, l'axe (a2) dudit second passage étant incliné d'un
second angle (β) par rapport à l'axe (ao) de ladite chambre et les axes desdits premier et second passages étant situés dans
le même plan diamétral de la chambre.
2. Dispositif à valve de demande d'air selon la revendication 1, caractérisé en ce
que ledit premier angle est compris entre 15° et 25° et ledit second angle est compris
entre 5° et 15°.
3. Dispositif à valve de demande d'air selon la revendication 1 ou 2, caractérisé
en ce que la distance (s) entre ledit axe (ao) de ladite surface latérale et le point d'intersection (C) de l'axe dudit second
conduit avec le plan qui délimite frontale- ment le conduit proprement dit, est comprise
entre 20 et 35% du diamètre de ladite chambre.
4. Dispositif à valve de demande d'air selon une des revendications précédentes, caractérisé
en ce qu'elle comprend un diaphragme, disposé à l'intérieur de ladite chambre et comprenant
au moins une paroi plane (29) placée au voisinage de l'embouchure dudit second conduit
et dans un plan qui est sensiblement parallèle audit axe (ao) de ladite surface latérale et perpendiculaire audit plan qui contient les axes des
conduits (a,, a2).
5. Dispositif à valve de demande d'air selon une des revendications précédentes, dans
lequel, en aval dudit élément de blocage (20), ledit conduit comprend un premier trou
sensiblement cylindrique (17) et un second trou (18) délimité par une surface conique,
caractérisé en ce que la demi- ouverture de ladite surface conique est comprise entre
16 et 18°.
6. Dispositif à valve de demande d'air selon la revendication 5, caractérisé en ce
que le rapport entre les longueurs axiales desdits premier et second trous est compris
entre 0,85 et 0,45.
7. Dispositif à valve de demande d'air selon les revendications 4 ou 5, caractérisé
en ce que les longueurs axiales desdits premier et second trous sont comprises respectivement
entre 4 et 6 mm et entre 7 et 9 mm.
8. Dispositif à valve de demande d'air selon une des revendications 5 à 7, caractérisée
en ce que le rapport entre le diamètre dudit premier trou et sa longueur axiale est
compris entre 0,85 et 1,32.
9. Dispositif à valve de demande d'air selon la revendication 8, caractérisé en ce
que le diamètre dudit premier trou est compris entre 5,1 et 5,3 mm.
10. Dispositif selon la revendication 1, caractérisé en ce que ledit soufflet (7)
comprend une surface de base (8) sensiblement plane et indéformable et apte à définir
ladite surface de base de ladite chambre, ainsi qu'une surface latérale déformable
(9) pourvue d'une pluralité d'ondulations.