Sealing lip device for a respiratory mask, respiratory mask and a method and a mould for producing the same

The invention relates to a sealing lip device for a respiratory mask, to a respiratory mask per se and to a method and mould for producing the same. According to the invention, the respiratory mask has an orifice (2) for receiving at least the nose tip of the mask wearer and a sealing lip (3) consisting of an elastomeric material, which surrounds the orifice and crosses the bridge of the nose. Said sealing lip has a supporting zone which lies against the face of a mask wearer. The elastic pliability of the sealing lip (3) is such that the sealing lip zone (a) which seals the area around the bridge of the nose has a greater pliability than the sealing lip zone (b1, b2, c) which lies adjacent to the nostrils and/or the upper lip of the mask wearer, when the mask is applied to the face of the latter. From a production method viewpoint, the synthetic material is introduced in two separate injection-moulding steps, a support structure (4) with thick walls being preferably configured in the first step.

This application is the National Phase of International Application PCT/EP00/01586 filed Feb. 25, 2000 which designated the U.S. and that International Application was not published under PCT Article 21(2) in English.

The invention concerns a sealing lip device for a breathing mask, a breathing mask per se and a method and a mold for producing same.

In particular the invention concerns breathing masks which can be fitted to the nose region in sealing relationship and which have a sealing device extending in the region of the upper lip of the mask wearer between the mouth and the nose. Breathing masks are used in particular in the medical and technical areas for the feed of a respiratory gas, in particular under an increased pressure.

In those breathing masks, a seal in relation to the surface of the face of a wearer is usually achieved by a peripherally extending sealing lip made from an elastomeric material.

The sealing action achieved with a sealing lip of that kind generally increases with the pressure with which the sealing lip is pressed against the surface of the face. However the level of wearing comfort is adversely affected by comparatively high contact pressures. Depending on the respective sensitivity of the mask wearer long-term use of the known breathing masks gives rise to troubles.

The object of the present invention is to provide a breathing mask in which a high level of sealing action can be reliably achieved, with a high degree of wearing comfort.

In accordance with the invention that object is attained by a sealing lip device for a breathing mask having a receiving opening for receiving at least the nose tip region of a mask wearer, a sealing lip which is formed from an elastomeric material and which surrounds the receiving opening and which crosses the bridge of the nose in the application position and which has a contact zone provided for bearing against the face of a mask wearer, wherein the sealing lip is elastically yieldingly arranged in such a way that in the region of the bridge of the nose there is a higher degree of flexibility than in the region of the nostrils and/or the upper lip.

That advantageously affords a high degree of compatibility with the most widely varying facial architectures, with a high level of wearing comfort. The breathing mask according to the invention is distinguished in particular in the region of the bridge of the nose by a high degree of sealing integrity, without considerable pressures in relation to surface area occurring in that respect. The high level of sealing effect achieved in the region of the bridge of the nose effectively obviates in particular eye irritation effects and feeling the effects of drafts.

In accordance with a particularly preferred embodiment of the invention the defined flexibility of the sealing lip zone which fits on the region of the bridge of the nose is achieved by the sealing lip device being suspended in the region of that zone on a bellow structure. That bellows structure is preferably dimensioned in such a way that it forms an abutment device, upon suitably deep penetration of the bridge of the nose. The abutment surfaces which come into effect there are preferably such that they form a comparatively large contact area, at the latest in the inwardly resiliently deflected condition, so that even when the bellows structure becomes operative in the resiliently inwardly deflected condition, the arrangement does not involve any unacceptably high pressures in relation to surface area.

In a particularly advantage fashion, a hinge characteristic which is defined by different wall thicknesses is imparted to the bellows structure. Preferably the bend or hinge location is of a comparatively thin-gauge nature, whereas the zones which are disposed therebetween are slightly thicker. As an alternative thereto or also in combination with that measure, it is also possible to provide rolling bellows structures, by virtue of suitable wall thicknesses.

In a particularly advantageous manner the bellows structure has a plurality of fold indentations. Preferably at least one fold indentation extends from the region of the bridge of the nose into a region adjacent to the nostrils in the position of use of the mask.

Particularly when the structure has a plurality of fold indentations preferably at least one thereof extends around the entire periphery of the sealing lip device. The spring characteristic of the respective fold indentation can be definedly established for given peripheral zones in such a way that there is a higher level of flexibility in the region of the bridge of the nose and there is a lower level of flexibility in the region of the upper lip or in particular in the region of the nostrils. (Those orientations are with reference to the application position of the mask).

Particularly when using the bellows structure in the sealing zone region of the bridge of the nose, the sealing device is preferably designed in such a way that the flexibility of the sealing lip, which is in opposite relationship to the application direction, is so matched that there is an adaptation or articulation axis in the nostril or upper lip region. That makes it possible for the corresponding breathing mask to be fitted to the face of the mask wearer predominantly in the region of the zones of the face which are adjacent to the nostrils and on the upper lip, in which respect the preferably extremely thin-wall sealing lip zone which is provided for sealing at the bridge of the nose can be pivoted with respect to the mask frame, in accordance with the facial architecture. By virtue of the internal pressure obtaining in the mask, that pivotably supported sealing lip zone can then be uniformly pressed against the bridge of the nose of the wearer of the mask, without in that situation the occurrence of surface pressures which considerably exceed the internal pressure of the mask.

The particularly advantageous kinematics and hinge characteristic of the mask cushion or pad formed by the sealing lip device can in particular be achieved by local zones with a higher load-bearing capability being provided in the region of the sealing lip, which is adjacent to the nostrils or the upper lip.

In accordance with a particularly preferred embodiment of the invention the zones of higher load-bearing capability are formed by locally thickened zones of the sealing lip. The transition of the locally thickened zones is preferably effected along regions in the manner of the edge of a lens, or also in a shallowly terminating configuration, possibly without the transition between the zones being clearly perceptible.

In accordance with a particularly preferred embodiment of the invention the locally thickened zones are supported on a mask frame zone by way of a support structure which is formed in the sealing lip. That mask frame zone is preferably of a thick-wall nature and in that respect involves a wall thickness in the range of between 3 and 6 mm.

The zones of higher load-bearing capability are preferably of a pad-like nature, as is shown by way of example inFIG. 1to which reference will be subsequently made in greater detail.

A form of support for the mask pad, which is particularly advantageous from ergonomic points of view is achieved if the zones of higher load-bearing capability, in the region of the face-contact zone, are each of a substantially crescent moon-shaped configuration. The limbs of those zones of higher load-bearing capability, which are provided in the region for bearing against the upper lip, are preferably of a shortened configuration in such a way that a zone of high elasticity and flexibility in opposite relationship to the application direction is provided in the region of the upper lip between the zones of higher load-bearing capability. That higher degree of flexibility can advantageously be achieved by also providing here a local fold structure or a correspondingly thin-walled zone.

In accordance with a particularly preferred embodiment of the invention the sealing lip device is mounted to a mask base body. The mask base body can also be formed from an elastomeric material, for example silicone rubber. In accordance with a particularly preferred embodiment of the invention however the mask base body is formed by a hard shell, for example comprising a fully transparent material. The hard shell preferably has a conduit connection facing in the application position towards the forehead region of the mask wearer. As an alternative thereto it is also possible for the hard shell to be provided with a central or lateral connecting structure for coupling a respiratory gas conduit.

Mounting the sealing lip device or the sealing pad to the hard shell or a mask base body is preferably effected by using a coupling structure. In accordance with a particularly preferred embodiment of the invention that coupling structure comprises, on the part of the hard shell, a peripheral bead portion and, on the part of the sealing lip device, a frame portion with a complementary receiving groove. The groove and the bead are preferably such that in the case of an expansion of the mask pad, caused by mask internal pressure, in the region of the coupling structure, there are surface pressures which are always higher than the internal pressure in the mask. That provides for a particularly reliable sealing action, without the addition of adhesives.

In a particularly advantageous fashion, there are provided means for fixing the position of the sealing lip device with respect to the hard shell in the peripheral direction. Those means can be formed for example by positioning projections or in particular by apertures in the peripheral bead.

A prestressing is preferably imparted to the sealing lip device, which prestressing is advantageously achieved by elastic deformation upon coupling to the hard shell. That makes it possible to definedly influence the deformation characteristics of the sealing lip device. In particular it is possible to prestress given zones of the sealing lip device in such a way that the formation of wrinkle folds in the region of the face-sealing zone is advantageously precluded.

In accordance with an advantageous embodiment of the invention the frame portion is such that it extends substantially in one plane. That permits the hard shell to be of a comparatively flat structure and allows the mask pad to be prestressed in a simple fashion.

As an alternative thereto however it is also possible for the mask arrangement to be designed in such a way that the frame portion is of a configuration which advances in the region of the articulation axis relative to the zone of high load-bearing capability. That makes it possible to already impart to the hard shell itself a configuration which substantially corresponds to the statistically most probable facial architecture.

Advantageously the wall thickness of the thin zone is in the range of between 0.65 and 1.85 mm. That wall thickness imparts to the mask a resistance to pressure which is sufficient even in the case of mask pressures in the region of 15 mbars.

The wall thickness of the zone of high load-bearing capability is preferably in the range of between 0.80 and 4 mm.

In accordance with a particularly preferred embodiment of the invention the mask pad is produced by a multi-stage mold cavity filling method. That makes it possible to impart to the zone of high load-bearing capability, a coloring which differs from the zone of low load-bearing capability. It is also possible to definedly match the mechanical properties of the materials respectively used for the respective zone.

The zone of high load-bearing capability is preferably formed by two elastomeric portions which project up from the lower corner region of the frame portion and which pass out into the sealing lip in the form of flat limbs. The sealing lip itself is preferably formed from an elastomeric material, in particular fully transparent silicone rubber. The outside surface of the mask pad, which comes directly into contact with the face of the mask wearer, is preferably of a velvety matte finish. That affords an improved feel when wearing the mask.

An embodiment of the invention which is particularly advantageous from manufacturing procedure points of view is afforded if the hard shell is injection molded to the sealing lip device. Besides particularly reliable coupling of the hard shell or the mask base body and the mask pad, that also precludes the formation of a gap, which is disadvantageous from bacteriological points of view.

In regard to a method of producing a sealing lip device for a breathing mask, the above-specified object is attained by an elastomeric material being introduced into a mold cavity formed by a mold, at least partially setting in the mold cavity, and being removed from the mold after opening thereof, wherein the elastomeric material is introduced into the corresponding mold cavity in two steps which occur in succession in time.

In that way it is possible to provide a mask pad which has a single sealing lip which in the application direction affords flexibility which is defined in accordance with the load-bearing capability and the statistically expected architectural variance of the corresponding zone of the face.

Advantageously, a carrier structure of the sealing lip device and a thin-wall zone of the sealing lip are formed in steps which are separate in terms of time, and possibly using materials involving different mechanical properties and possibly color.

Preferably the carrier structure is formed in a first injection step and the thin-wall zone is formed in a subsequent second injection step. The operation of introducing the respective material is preferably effected by injection or beforehand by suitably introducing same into the mold cavity to fill it.

The mold cavity which is provided for filling with the material forming the thin-wall zone is preferably defined by a mold which delimits the outside of a sealing lip being lifted off a core which delimits the inside of the sealing lip.

As an alternative thereto it is also possible for the carrier structure to be formed by a mold cavity which is defined by a core delimiting the inside of a sealing lip and an outer mold, wherein to form the thin-wall zone of the sealing lip the outer mold is changed and then the material for forming the thin zone is introduced into the mold cavity which is now present and which is intended for the thin-wall zone, and sets therein.

In the mold aspect of the invention, the above-specified object is attained by a mold for producing a sealing lip device for a breathing mask, comprising a mold core device which in conjunction with an outer mold defines a mold cavity having a fold portion.

It is advantageously possible in that way to produce the sealing lip device for example in the context of a fully automated silicone injection molding method.

In accordance with a particularly preferred embodiment of the invention the outer mold is of a multi-part nature. Preferably the outer mold comprises a mold half which delimits the outside surface of the sealing lip and a mold half which co-operates with said mold half and which delimits the rest of the region of the outside surface of the sealing pad. The inner region of the sealing pad is delimited by a preferably integral core device. With the described two-part embodiment of the outer mold, it is possible for an outer mold half to be withdrawn along a mold-opening axis which extends in a direction in opposite relationship to the side at the bridge of the nose or a direction remote from the upper lip sealing zone. The bellows zone which is locally provided in the region of the bridge of the nose and the mold-opening axis as well as the configuration of the coupling frame of the mask pad are preferably matched in such a way as to afford mold-opening angles at least in the region of 2°.

In particular in this case the outside of the sealing lip, which is towards the mask wearer, is preferably formed by an outer mold portion in conjunction with the mold core device, wherein the outer mold portion has a peripherally extending mold cavity channel which defines the outside of the sealing lip.

The outer separation edge of the mold cavity channel preferably extends in the region of the outer peripheral edge of the sealing lip. That advantageously avoids any burrs in the region of the face-contact surfaces.

In accordance with a particular aspect of the invention, an embodiment, which can be particularly advantageously implemented from production procedure points of view, of a leakage device for the discharge of at least partially consumed respiratory air into the ambient atmosphere is afforded by a breathing mask having a mask body and sealing pad device which is formed from an elastomeric material and which in conjunction with the mask body delimits a mask internal space and an outlet device for the discharge of at least partially consumed respiratory gas out of the mask internal space, wherein the outlet device has a flow path portion which is at least partially defined by the sealing pad device.

This measure can also be used independently of the above-described design configurations. Advantageous developments of this combination of the invention, which is independent per se, are set forth in the appendant claims.

Further advantageous configurations of the invention are recited in the appendant claims.

The sealing lip device which is shown inFIG. 1and which is in the form of a mask cushion or pad1is made from an elastomeric material, here transparent silicone rubber.

The mask pad1includes a sealing lip3which extends around the nose receiving opening2. The sealing lip3has an outer surface which is curved convexly in the embodiment illustrated here.

The sealing lip3is of such an arrangement and configuration that it has, of itself, zones of differing load-bearing capability. In the embodiment illustrated here that is achieved by suspension, which is flexible in opposite relationship to the application direction Z, of the sealing lip zone a provided for bearing against the bridge of the nose (see sketch K1).

In addition thereto, in the region of the zone b1, b2(sketch K1) adjacent to the nostrils, the sealing lip3is of such a configuration that here it is of a higher load-bearing capability. That provides for pivotability of the mask pad about an adaptation axis X, which extends transversely through the mask pad in the region identified in sketch K1by the letter e.

The higher load-bearing capability is achieved here by zones4which are thickened in a pad-like manner and which here advantageously run into the sealing lip3in a crescent moon-like configuration. The zones4of higher load-bearing capability are respectively supported at a support wall portion5which is also comparatively thick-walled. The support wall portions5also form an integral component part of the mask pad1and are embodied in the form of thick-wall zones of the front peripheral wall which extends in the zones b1, c and b2.

The degree of flexibility in opposite relationship to the application direction decreases along the sealing lip3, starting from the zones4of high load-bearing capability, to the zenith Q at the side at the bridge of the nose, and then slowly rises to the outer edge point R.

In the illustrated embodiment, the mounting of the zone a of the sealing lip3, which is yielding in opposite relationship to the application direction Z, is achieved by means of a folding bellows structure of differing load-bearing capability.

The differing load-bearing capability is achieved here both by the geometry and arrangement of the bellows structure and also by a particular wall thickness configuration. That wall thickness configuration will be discussed in greater detail hereinafter in particular with reference toFIGS. 5 and 6.

The mask pad1further includes a peripherally extending frame8provided with a fixing profile means which is of a complementary configuration to a fixing profile portion provided on a mask base body (not shown).

The peripheral length of the frame8and the configuration thereof around a central axis z of the mask pad1are selected in such a way that, in conjunction with a mask base body, the arrangement provides for defined prestressing of the mask pad1, in particular a tendency towards forward curvature in an outward direction.

In the illustrated embodiment the wall thickness of the sealing lip3is in the range of between 0.6 and 3.2 mm.

The configuration of the peripheral edge u which borders the nose receiving opening2is selected in such a way that there are formed two segments s1, s2(sketch K3) which project inwardly slightly relative to the axis z of the mask.

By virtue of the configuration of the peripheral edge u being matched to the convex curvature of the sealing lip3, it is possible to achieve a deformation characteristic with which an expansion of the sealing lip3in the region of the peripheral edge results in a definedly increased surface pressure against the face of the wearer of the mask.

Provided in a front end center region c is a further zone of reduced load-bearing capability. That definedly reduced load-bearing capability is afforded here by a markedly reduced wall thickness. It is also possible to provide local folding bellows structures or rolling bellows structures in the zone c.

A particularly preferred embodiment of a sealing lip device is afforded by virtue of the fact that integrated into same are outlet openings50, by way of which a defined flow of gas can flow away out of the interior of the breathing mask. Those outlet openings are preferably of an outwardly conically tapering cross-section, as shown in sketch K2.

Preferably, those outlet openings are initially closed for example by a thin film and are then opened as required for example by puncturing with a needle. As can further be seen from this sketch the mask pad1can be mounted to a mask base body12by way of a frame portion8. For that purpose the arrangement preferably has a peripheral bead structure of a crochet needle-like cross-section and with rounded edges.

FIG. 2shows a side view of a further embodiment of a mask pad1. In this embodiment the frame8extends substantially in a flat frame-defining plane f.

The mask pad1also has in the sealing region of the bridge of the nose a local folding bellows structure9which provides for flexible suspension of the sealing lip3.

A fold indentation10is also provided in the front region c (definition similarly to the sketch K1inFIG. 1). The arrangement afforded in that way defines an adaptation and articulation axis X or an instantaneous center of rotation about which the sealing lip3can be elastically tilted. The arrangement here is such that tilt angles α in a range of up to 15° are possible. Besides the tilting movement itself the sealing lip3can also experience individual deformation, corresponding to the facial architecture. In particular the peripheral edge u of the nose receiving opening is stretched.

When relatively large tilt angles are involved, here the bellows structure becomes effective as an abutment device and limits in an also elastically yielding manner further engagement of the bridge of the nose into the mask pad1.

The bellows structure9has the greatest indentation depth t in the region of the end which is towards the bridge of the nose. That indentation depth t gradually decreases to the front end E of the bellows structure9.

In the embodiment illustrated here, the end of the bellows structure9is of a rounded configuration. Advantageously, provided in the region of the front end E of the fold indentation is a microfold structure e which provides for a more uniform reduction in stresses in the material in that region. That affords improved durability.

FIG. 3ashows a further embodiment of a mask pad1in conjunction with a mask body12which is only indicated.

This embodiment also has a local folding bellows structure9. The geometry of this bellows structure9is so selected that the fold flanks9a,9bextend inclinedly relative to each other. Overall in this case also the indentation depth t in the region of the end towards the bridge of the nose is larger than in the other regions. The mask pad1also defines an adaptation axis X which extends in the region of the zones c1, b2and c at the level of the nostrils of the wearer of the mask.

The mask pad1also has a higher degree of flexibility in opposite relationship to the application direction Z by virtue of the suspension arrangement provided here for suspending the sealing lip3at a local bellows structure9, in the region of the zone a which seals off the bridge of the nose.

FIG. 3bshows a further view of a breathing mask with a mask pad1according to the invention. The mask pad1is here fixed by way of a frame8to a mask base body12. A bellows structure9is provided here in the region of the portion of the sealing lip3which seals off the bridge of the nose. In a departure from the above-described embodiments in this case also the peripheral wall of the mask pad is also of thin-wall configuration in the region of the bellows structure9. The mask pad1is stretched onto the mask base body12with considerable expansion and stretching of the frame8.

FIG. 4, in conjunction with a plan view onto a half of the sealing lip3, illustrates the load-bearing capability and the flexibility of the mask pad1.

The lowest level of flexibility E of the mask pad1obtains in the region b. The highest level of flexibility obtains in the region a which covers over the bridge of the nose and the upper side flanks of the nose of the mask wearer. Obtaining in the region c in addition to the flexibility in opposite relationship to the application direction Z there is also a relatively high level of flexibility in the radial direction.

The adaptation axis A extends through the zone b of relatively high load-bearing capability. When a predetermined depth of penetration into the mask pad1is exceeded, the bellows structure becomes operative in a region d as an abutment device and in that case causes a rapid rise in the pressure force F transmitted by way of the sealing lip3, as is indicated by the dash-dotted line portion f1.

The particular mechanical properties of the suspension arrangement for the sealing lip3are preferably determined by the wall thickness in the region of the bellows structure9and by the indentation depth and the orientation of the bellows flanks9a,9b(FIG. 3a).

FIG. 5shows a preferred configuration of the wall thicknesses of the bellows structure9. The mask pad1is fixed to a mask base body12in this case by way of a rounded profile structure12awhich extends along the frame8. In the illustrated embodiment that profile structure12ais of a crochet needle-like cross-section. Provided at least in a portion-wise manner in the region of the contact zone between the frame8and the mask base body12are peripherally extending profile legs15which, even in the case of a considerable relative movement, provide a secure sealing action.

Beneath the frame8there is initially a thick-wall portion16which gradually reduces to a first bellows hinge location17. That bellows hinge location17is adjoined by a first bellows flank limb9b. That bellows flank limb9bhas in cross-section zones of differing wall thickness and extends to a bellows inner hinge location18defined by a thin-walled zone.

The bellows inner hinge location18is in turn adjoined by a second bellows flank limb9awhich also has zones of differing wall thickness.

Finally, the sealing lip3is suspended on the second bellows flank limb9a. The sealing lip3is here extremely thin-walled in comparison with the bellows structure9.

The sealing pad cross-section illustrated here corresponds in qualitative terms to the sealing pad cross-section in the region of the zone identified as a1inFIG. 4.

In the course of applying the mask pad to the face of a mask wearer, the sealing lip3firstly bears against the face. The bellows flank limbs9a,9bare then deflected resiliently inwardly, corresponding to the depth of engagement of the bridge of the nose, as illustrated by the arrows P1and P2. In the case of particularly deep engagement of the bridge of the nose the inner surface of the sealing lip3possibly comes into contract in the region of the zone k with the inside surface, which faces theretowards, of the bellows flank limb9b. The bellows flank limb9bin turn can bear on the outside surface, which faces theretowards, of the bellows flank limb9a.

The kinematics of the sealing pad suspension configuration will be clear by reference to the accompanying functional sketch S1. Thus the frame can be viewed as a fixed suspension means K1at which the bellows flank limb9bis mounted pivotably at the hinge location17. The inherent elasticity of the elastomeric material in the region of the hinge location17is symbolically indicated by the spring F1.

The bellows inner hinge location18also involves an inherently elastic characteristic which is indicated by the spring F2. The loose mounting K2and the spring F3are due to the fact that this involves a spatial, ring-like structure which also carries forces in the radial direction.

The hinge location18is adjoined by the bellows flank limb9band same is adjoined by the diaphragm-like sealing lip3.

Provided along the inner peripheral edge u is a microsealing lip structure by which a sealing edge which terminates in a thin configuration is slightly prestressed outwardly. The microsealing lip structure has a bead portion19which increases the resistance to tearing of the sealing lip3.

The mechanics of this microsealing lip structure is indicated in sketch S1by a spring F4and a hinge location20. The sealing lip which is elastically suspended in that way, as indicated by the small arrows, can be urged flexibly against the surface of the face of the mask wearer, as a consequence of the internal pressure obtaining in the interior of the mask.

As can be seen fromFIG. 6the mask pad1is preferably of differing cross-sections along its configuration around the axis Z of the mask, as is diagrammatically indicated here.

The cross-section Q1has a marked hinge characteristic with abutment properties.

The cross-section Q2already has a lower hinge characteristic and a smaller fold indentation.

In the region of the cross-sections Q3, Q4the bellows property decreases still further.

The higher load-bearing capability of the cross-sections Q4and Q5is achieved by local thickenings R1, R2which extend lens-like into the sealing lip. In the zones of high load-bearing capability, it is possible to forego the bellows structure, as has happened here.

The cross-sections Q6aor Q6bare such that there is flexibility in the directions r1and r2indicated here. That affords improved adaptability, in terms of the upper lip architecture, immediately beside the load-bearing zones.

It is also possible for the bellows structure9to be of a thin-wall nature. The kinematics of a structure of that kind is diagrammatically shown inFIG. 7. The diaphragm-like sealing lip3is here suspended on two limbs (bellows flank limb9a,9b). This embodiment, even with low internal pressures in the mask, guarantees a high level of adaptability. The elasticity characteristics are illustrated, with reference to a unit force, for all loading angles, by the polar diagrams II1,112which are diagrammatically shown here. As can be seen, a defined degree of adaptability is afforded by the suspension arrangement according to the invention for the sealing lip3, not only in opposite relationship to the application direction Z but also in all other directions. The location vectors t1, n2, n3and n4clearly show that flexibility in the region of the bellows inner hinge location. The mobility options of the bellows inner hinge location18are also transmitted (under the influence of the mask pad peripheral forces) to the suspension region of the sealing lip3.

FIG. 8diagrammatically shows a profile structure21which is provided in respect of a mask base body12and which advantageously provides for reliable fixing of the mask pad in the peripheral direction. The illustrated embodiment for that purpose has a plurality of individual fixing projections22along the periphery of the mask base body12. As an alternative thereto or also in combination with that measure, it is also possible to provide further fixing means, in particular peg-like projections.

FIG. 9shows in greatly simplified form the structure of a mold for producing the mask base body12. By virtue of the aperture in the peripheral bead23in the region of the respective strap loops, it is possible for the strap loops to be injection molded integrally with the mask base body12, without the need for sliding mold portions in that respect.

In the embodiment of the mask base body12diagrammatically illustrated here, provided in parallel with a respiratory gas passage24is a secondary passage25by way of which for example pressure measurement can be effected, without reductions in cross-section occurring in that case.

The tool here is of a three-part construction and includes an upper mold half26, a lower mold half27and a sliding mold portion28which can be withdrawn in the direction r3from the respiratory gas passage24.

Although the invention has been described hereinbefore with reference to preferred embodiments in which there is a single fold indentation which does not extend around the entire periphery of the mask pad, the invention is not limited to embodiments of that kind.

For example it is possible for the bellows structure to be provided with a plurality of fold indentations, of which possibly one or more extend around the entire periphery of the mask pad.

An example of a corresponding cross-sectional configuration is shown inFIG. 10. The mask pad1which is here fixed to a mask base body12which is only indicated in respect of a portion thereof, by way of a peripheral bead structure of a crochet needle-like cross-section, has two local fold indentations39,49. The wall of those local fold indentations39,49is matched in regard to a defined hinge and flexibility characteristic.

In this embodiment the sealing lip3is of a comparatively thick-wall nature. That cross-section is suitable in particular for silicone rubber material with an extremely low Shore hardness.

The breathing mask shown inFIG. 11includes a mask base body12which is made from a preferably fully transparent thermoplastic material. Provided in a wall portion which in the application position of the mask is adjacent to the forehead region of the mask wearer is a connecting portion60which here is of a polygonal cross-section.

The sealing pad device3is fixed to the mask base body12by way of a peripheral bead structure (not visible here). The sealing pad device3has a bellows structure which extends locally from the upper end region to an adaptation axis A. Provided in the region of the adaptation axis A on both sides of the sealing pad are zones of higher load-bearing capability which are formed by thicker-walled, spherically curved zones of the sealing pad device.

For the purposes of fitting the breathing mask to the face of a mask wearer, provided at both sides of the mask are fixing devices61, by way of which a head band can be coupled to the breathing mask.

On its top side the mask body12is provided with a projection62by which the mask body generally is stiffened, thereby affording an improved characteristic in terms of sound conduction through solids.

Also provided in the region of the top side of the mask body12are a plurality of outlet openings63,64, by way of which a low-noise, directed discharge flow of partially consumed respiratory air can occur from the interior of the mask. The discharge of that leakage gas flow is promoted by a break-away edge65of a spoiler-like configuration. The openings64direct the flow substantially in the direction indicated by the arrow P1. The openings63which are also provided on the opposite side (not visible here) of the projection62open in the directions P2and P3.

FIG. 12shows the breathing mask ofFIG. 11from a direction of view which is directed inclinedly from below onto the zone4of high load-bearing capability. It is also possible to see here, beside the local bellows structure9, the region of the sealing lip3which bears against the face of the mask wearer. In the region of the zone a the mask is distinguished by a high level of adaptability to different nose bridge heights. In the zones b1and b2the mask pad1is supported in a defined manner against the face of the mask wearer. In the region c once again there is a higher level of flexibility and a higher degree of adaptability to different upper lip contours.

The mask pad is of such a design configuration that there is a relief of load in the region of the zones b1and b2, as a consequence of the internal pressure in the mask which occurs in the context of over-pressure artificial respiration. The surface pressure of the mask pad in the region of the zones a and c is substantially determined by the internal pressure in the mask. In the peripheral direction the sealing pad1has a high level of radial stiffness whereby the tendency to oscillation of the sealing pad in relation to alternating artificial respiration pressures is markedly reduced.

FIG. 13is a greatly simplified view in section through the region of the sealing lip device3, which fits on the upper lip70of a mask wearer. In a transitional region from the sealing pad device into the hard shell body12, the configuration of the cross-sections of the sealing pad device3and the hard shell body12is such that there is a substantially smooth transition in respect of the respective internal surfaces. That ensures a favorable flow path directly in the region of the nostrils of the mask wearer.

As indicated, in this case also there is a local bellows structure66which ensures improved adaptability to different upper lip architectures.

FIG. 14ashows a portion of the arrangement illustrating the transitional region between the hard shell body12and the sealing pad device1. Formed directly in the sealing pad device1is a leakage opening67which is here of a cross-section which decreases in the discharge direction. The cross-sections of that leakage opening67are preferably of the configuration diagrammatically shown inFIG. 15.

FIG. 14bshows a further embodiment of a leakage opening68which is integrated into the sealing pad device1. In the embodiment illustrated here a wall formed by the hard shell body12extends into the flow path. This embodiment can be cleaned in a particularly advantageous manner as the flow path is exposed over a large area after removal of the sealing pad device1from the hard shell body12. Illustrated in the sketch shown immediately therebeside is a view of a detail of that sealing pad, in the direction of view identified as x1. As can be seen therein the peripheral bead12aof the hard shell body12extends partially into the recess69formed in the cushion pad device1.

In the embodiment shown inFIG. 14c, provided in the region of the join between the hard shell body12and the sealing pad device1in the hard shell body is a channel portion70by way of which there can be a discharge flow of gas, as indicated by dash-dotted lines. The exit region of the channel portion70, as illustrated, opens into a outlet passage71which is defined jointly by the sealing pad device3and the hard shell body12.

In the embodiment shown inFIG. 14d, provided in the hard shell body12is at least one outlet passage72which goes into an aligned discharge passage73in the sealing device1.

FIG. 14eshows an embodiment of a leakage device in which a wall portion74which is integral with the sealing pad device1is taken from the interior to an outlet opening region75of the hard shell body12. That wall portion74is here provided with an outlet opening67which tapers conically in the discharge direction and which is arranged coaxially with respect to a preferably considerably larger outlet opening75a.

The flow paths described with reference toFIGS. 14athrough14eare preferably of at least one of the cross-sections diagrammatically shown inFIG. 15.

FIG. 16indicates a preferred location for providing the discharge flow openings which are provided jointly with the sealing pad device1or also separately therefrom. Preferably the discharge flow occurs in the region of the zone c in combination with the zones b1and b2, but preferably larger volume flows are admitted in the region c.