Pressure relief valve

Abstract

Pressure relief valve with a gas inlet section (20), a gas outlet section (22) and a diaphragm (18) arranged between the gas inlet section (20) and the gas outlet section (22), the diaphragm being adjustable between at least one open position and a closed position depending on the pressure, wherein in the closed position the diaphragm (18) comes into contact with a contact surface (24) upstream of an opening cross-section (26) of the gas outlet section (22), wherein a diaphragm support structure (32) is formed or arranged in the opening cross-section (26) of the gas outlet section (22), with which the diaphragm (18) comes into contact at least partially in the closed position, wherein the diaphragm support structure (32) comprises at least one rib (42) extending radially from an inner circumferential wall (36) of the gas outlet section (22) into the opening cross-section (26),which is designed as a support rib and extends from a first contact point (38) of the inner circumferential wall (36) to a second contact point (40) of the inner circumferential wall (36) and / or the membrane support structure (32) comprises at least one central rib (52) extending at least partially in the direction of extension of the opening cross-section (26) and passing through the central axis of a circular opening cross-section, characterized in that the membrane support structure (32) is arranged or designed to be set back from the contact surface (24) when viewed in the direction of flow.

Description

The invention relates to a pressure limiting valve according to the preamble of claim 1.DE 44 16 119 B4 discloses a pressure limiting valve, referred to as a crankcase ventilation valve, having a sheet metal housing and a sheet metal housing cover, wherein a membrane is clamped between the sheet metal housing and the sheet metal housing cover. Depending on a differential pressure between an intake tract negative pressure and an atmospheric pressure, the diaphragm closes a valve seat on the sheet metal housing. Acoustic problems and measures for improving acoustics are not described in the document.EP 1 843 234 A1 discloses a pressure limiting valve for regulating the pressure in a crankcase of an internal combustion engine. The pressure limiting valve has a gas inlet section referred to as gas inlet and a gas outlet section referred to as gas outlet, wherein a membrane is arranged as a separating element between these sections. In an open position of the membrane, gas can flow from the gas inlet to the gas outlet. In a closed position of the membrane, the membrane abuts against an abutment surface and separates the gas inlet section from the gas outlet section. In order to improve the control behavior of the pressure limiting valve, according to EP 1 843 234 A1, the passage cross section between the diaphragm and the contact surface of the valve seat is to be formed tapering towards one side. Thus, a two-stage closing movement of the diaphragm at the valve seat is to be produced.A disadvantage of the known pressure limiting valves is that a noticeable, undesirable pumping noise can occur during the closing and opening of the pressure limiting valve and / or in the closed state in the event of pressure fluctuations.EP 1 723 480 B1 discloses a pressure limiting valve having the features of the preamble of claim 1.Against this background, the object of the invention is to provide an acoustically improved pressure limiting valve.The object is achieved according to the invention with the features of the independent claims. Further practical embodiments and advantages of the invention are described in connection with the dependent claims.A pressure limiting valve according to the invention has a gas inlet section, a gas outlet section and a membrane arranged between the gas inlet section and the gas outlet section. The membrane is arranged between the gas inlet section and the gas outlet section to the extent that the membrane is arranged so as to be adjustable in a pressure-dependent manner between at least one open position and one closed position and comes to bear in the closed position with a contact surface upstream of an opening cross section of the gas outlet section in such a way that the gas inlet section and the gas outlet section are separated from one another in fluid form. The membrane is moved in particular into the closed position when a certain negative pressure is exceeded in the region of the gas outlet section relative to the region of the gas inlet section. In the opening cross section of the gas outlet, a membrane supporting structure is formed or arranged, with which the membrane additionally comes to bear at least partially in the closed position.Due to the partial contact of the membrane with the membrane supporting structure in the closed position, effected with the aid of the membrane supporting structure, the size of the oscillatable membrane surface can be reduced and / or distributed over several partial surfaces. As a result, the resonant frequency of the diaphragm can be reduced, which in turn makes it possible to design the diaphragm as a function of resonant frequencies to be eliminated by suitable diaphragm supporting structures in such a way that the resulting resonant frequency in the closed position lies outside certain pressure oscillations which occur during operation, in particular during operation of an internal combustion engine in which such a pressure limiting valve is used. Noise formation caused by pressure fluctuations or by other excitations occurring as a result of operation can thus be counteracted simply and cost-effectively.Furthermore, the membrane supporting structure comprises at least one rib extending from an inner circumferential wall of the gas outlet section radially into the opening cross section and / or the membrane supporting structure comprises at least one central web extending at least partially in the direction of extension of the opening cross section and running through the central axis of a circular opening cross section. It is also possible to provide a plurality of ribs and / or central webs, in particular ribs distributed uniformly over the circumference of the opening cross section or a central web running through the central axis of a circular opening cross section or a plurality of such central webs. It is likewise possible for a rib to be provided in the form of a radially inwardly projecting collar portion which extends completely over the circumference, or for a plurality of ribs to be provided in the form of radially inwardly projecting collar portions which extend only over arcuate portions. One or more such ribs can be formed easily and cost-effectively, in particular integrally, on the inner circumferential wall of an opening cross section. Alternatively or in addition thereto, central webs can be formed simply and cost-effectively, in particular in one piece, with another region of the opening cross section of the gas outlet section.In addition, at least one rib is designed as a supporting web and extends from a first contact point of the inner circumferential wall to a second contact point of the inner circumferential wall. Such a supporting web can be formed particularly easily as a leaflet of a circular opening cross section, in particular in the form of a supporting web bisecting the opening cross section in a straight line. Such a central arrangement of the supporting web in an opening cross section has the advantage that the membrane in a closed position is divided into two identically sized, oscillatable partial surfaces which are oscillation-decoupled from one another by the supporting web. The supporting web is preferably arranged such that the membrane is bent in the direction of the supporting web by the negative pressure prevailing in the closed position and is resting on the supporting web.For the granting of the sealing function of the membrane and for acoustics, it is advantageous if the membrane supporting structure is arranged or formed set back with respect to the contact surface of the gas outlet section as viewed in the flow direction. In experiments it has proven particularly suitable in this regard if the membrane support structure has a support structure bearing plane, which is preferably planar and is arranged slightly set back with respect to the bearing surface, in particular by a dimension between 0 mm and 5 mm inclusive. The support structure bearing plane is preferably arranged recessed by a maximum of 1 mm with respect to the bearing surface, and particularly preferably arranged recessed by approximately 0.5 mm. Such an arrangement is suitable in particular for pressure limiting valves with an inner diameter of the opening cross section of the gas outlet section of 8 to 12 mm, in particular of 10 mm.In particular, if the configuration of a support rib is not sufficient from the standpoint of oscillation, it may be advantageous to arrange two support webs in an x-shape with respect to one another, in particular at right angles to one another in the form of a support cross. The support webs arranged in an x-shape can significantly reduce the oscillatable partial surfaces, which has a particularly positive effect on the change of the resonant frequency in the closed position. X-shaped supporting webs can also be selected in order to reduce the wall thickness of the webs and nevertheless to achieve a sufficiently rigid membrane supporting structure with only a small reduction in cross section. For the same reasons, more than two supporting webs can also be formed-in particular formed with only a small wall thickness-for example three, four, six, eight, ten or more supporting webs arranged in the form of a grid or star.The width of at least one rib, preferably of all ribs (for example in the form of supporting webs), perpendicular to the main direction of extent of the respective rib is preferably between 1% and 20% of the cross-sectional width of the gas outlet section. Preferably, the width is between 3% and 17% and more preferably between 5% and 15% of the cross-sectional width. With a cross-sectional width of 10 mm, for example, a width of the supporting webs of 1 mm is thus obtained at a value of 10%. With such a design, significantly improved acoustics have been obtained in experiments with only insignificantly changed flow behavior in the opening cross section of the gas outlet section.In a further practical embodiment, the membrane supporting structure is formed integrally with the circumferential wall of the gas outlet section and / or integrally with another region of the opening cross section of the gas outlet section. As already mentioned, in this case a particularly simple and cost-effective production results. The additional costs compared to variants without a membrane supporting structure are in this case limited substantially to a slight additional material costs. The production or assembly times, on the other hand, remain unchanged.The invention was developed in particular for a specific type of pressure limiting valve, in which the diaphragm is fixed in an outer region between a housing and a housing cover, and the diaphragm is furthermore arranged in a radially inner region within a separately produced diaphragm plate. The arrangement of the membrane in the membrane plate is preferably effected by a clamping connection similar to a snap-fastener principle. Furthermore, in the case of the aforementioned type of pressure limiting valve, a restoring element is arranged between the diaphragm plate and the housing or the housing cover, which restoring element generates an opening force counteracting the movement of the diaphragm into the closed position. A restoring element generating the opening force is in particular a spring, preferably a helical spring, which counteracts a closing movement of the membrane, so that the latter closes the gas outlet section only from a certain negative pressure, that is to say only from a suction effect which is greater than the opening force. The restoring element is preferably designed such that the membrane moves into the closed position from a reduced pressure of approximately 100 mbar.The invention also relates to any desired pressure limiting valve as described above, wherein the diaphragm has an at least partially curved position in the region adjoining the opening cross section at least in the closed position and / or is inclined in an open position with respect to the perpendicular to the direction of extent of the opening cross section. Due to a partially curved position in the closed position-and preferably also in the open position-internal material stresses arise in the oscillatable surface of the membrane, which leads to a positive change of the resonance frequency with respect to the acoustic behavior of the membrane in the closed position. With a membrane arranged inclined with respect to the perpendicular to the direction of extension of the opening cross section, similarly positive changes of the resonance frequency can be effected.A curved position of the membrane can be brought about in particular by a suitable configuration of a membrane plate and the fixing of the membrane in the membrane plate. For this purpose, the membrane plate can be designed, for example, in such a way that it fixes the membrane in a curved position. This can be effected in particular by connection regions varying in the circumferential direction, which are arranged in such a way that a curved surface arrangement is enforced on the membrane after its fixing with respect to the connection regions.In a further practical embodiment, which can be combined with all the embodiments described above, the contact surface is of planar design and is inclined with respect to a plane perpendicular to the direction of extent of the opening cross section by an angle between 0° and 5°. With such a tendency, particularly positive acoustic improvements have been achieved with respect to the pumping noises explained at the beginning.The membranes as described above can be produced in particular from an elastomer. Particularly suitable for the membrane are, in particular, silicones or FVMQ. The gas outlet section and also the housing and the housing cover can be made of plastic, for example of PA 6.6.A pressure limiting valve according to the invention as described above is suitable in particular for use as a crankcase ventilation valve for a crankcase of an internal combustion engine for discharging blow-by gases. In this case, the gas inlet section is connected in a flow-conducting manner to the crankcase, and the gas outlet section is connected to an intake tract of the internal combustion engine. Starting from a preset negative pressure in the intake tract, the membrane is caused to move into a closed position, so that venting no longer takes place. An excessively high negative pressure in the crankcase can thereby be avoided.Further practical embodiments of the invention are described below in conjunction with the drawings. The following are shown: FIG. 1 shows a first embodiment of a pressure limiting valve according to the invention in a cross-sectional illustration, FIG. 2 shows the region marked II from FIG. 1 with a gas outlet section and a membrane supporting structure in a schematic cross-sectional illustration, FIG. 3 shows the gas outlet section of the first embodiment from FIGS. 1 and 2 without membrane in a sectional illustration along the line III-III through the membrane supporting structure in FIG. 2, FIG. 4 shows the gas outlet section of a second embodiment of a pressure limiting valve according to the invention in a sectional illustration analogous to FIG. 3, FIG. 5 shows the gas outlet section with a membrane in the open position according to a third embodiment in a schematic cross-sectional illustration in a view analogous to FIG. 2, FIG. 6 shows the gas outlet section with a membrane in the closed position according to a fourth embodiment in a schematic cross-sectional illustration in a view analogous to FIG. 2, FIG. 7 shows the gas outlet section with a membrane in the open position according to a fifth embodiment in a schematic cross-sectional illustration in a view analogous to FIG. 2, FIG. 8 shows the gas outlet section without membrane according to a sixth embodiment in a view analogous to FIG. 3, FIG. 9 shows the gas outlet section with a membrane almost in the closed position according to a seventh embodiment in a schematic illustration in a view analogous to FIG. 2 and FIG. 10 shows the gas outlet section in a sectional illustration according to the arrows X-X in FIG. 9.FIG. 1 shows a cross section of a first embodiment of a pressure limiting valve 10. The pressure limiting valve 10 comprises a housing 12 and a housing cover 14. In the central region of the membrane 18, a membrane plate 16 is arranged on the latter. The diaphragm plate 16 serves as an abutment for a restoring element 28 in the form of a helical spring 30, the helical spring 30 being supported by its other end on a surface of the housing 12 which is not illustrated.The membrane 18 is shown in an open position in FIG. 1. The diaphragm 18 is made of an elastic material and can move together with the diaphragm plate 16 in the direction of the arrow S into a closed position. In the closed position, the membrane 18 comes to bear against a bearing surface 24 of an opening cross section 26 and thus prevents a gas flow from a gas inlet section 20 situated upstream of the opening cross section 26 in the direction of a gas outlet section 22 situated downstream of the bearing surface 24.As can be seen in FIG. 1, the thickness of the diaphragm 18 varies in the radial direction. The diaphragm 18 has a comparatively large thickness in the region of a radially outer edge and in a central sealing region and a comparatively small thickness in an elastic intermediate region. Within the respective regions, the thickness is largely constant.With the already mentioned helical spring 30, an opening force is exerted on the diaphragm 18 in the direction of the open position.The pressure limiting valve 10 shown is a crankcase ventilation valve which is used for the pressure regulation of the ventilation of a crankcase of an internal combustion engine. The gas inlet section 20 is connected to the crankcase in a flow-conducting manner and the gas outlet section 22 is connected to an intake tract of the internal combustion engine.If a negative pressure predetermined by the helical spring 30 is exceeded, a force is exerted on the diaphragm 18 which is greater than the opening force caused by the helical spring 30, which-depending on the level of the negative pressure-leads to a complete or partial movement of the diaphragm 18 into the closed position. As soon as the membrane 18 comes to bear completely against the contact surface 24 of the gas outlet section 22 (cf. FIG. 2 ), the pressure limiting valve 10 is closed.As already mentioned, during operation of an internal combustion engine, oscillations can be generated, in particular as a result of pressure pulsations, which oscillations are transmitted to diaphragm 18. This can lead to undesired noises, in particular in the closed position of the diaphragm 18. It has been found that such undesirable noise occurs particularly when a diaphragm 18' known from the prior art assumes the position shown in dashed lines in FIG. 2. In such a position, such a membrane 18' known from the prior art can oscillate over its entire surface within the opening cross section 26.With the embodiment of a pressure limiting valve 10 according to the invention shown in detail in FIGS. 2 and 3, such noises can be avoided by a membrane supporting structure 32 in the form of a rib 42 being formed in the opening cross section 26 of the gas outlet section 22. As can be clearly seen in FIG. 3, the rib 42 according to the first embodiment is designed in the form of a supporting web bisecting the opening cross section 26. In the closed position, the membrane 18 comes into contact with this supporting web and is thus supported on it, which can be seen clearly in FIG. 2.As can be clearly seen in FIGS. 2 and 3, the membrane supporting structure 32 is formed in the opening cross section 26 of the gas outlet section 22 in one piece with the circumferential wall 34 of the gas outlet section 22. The rib 42 serving as a membrane supporting structure 32 extends from a first contact point 38 of an inner circumferential wall 36 of the gas outlet section 22 in a straight line as far as a second contact point 40 of this inner circumferential wall 36 and thus forms a supporting web within the meaning of the invention. The diaphragm 18 engages the rib 42 in the closed position, as shown in FIG. 2. This results in two oscillating partial surfaces 44 a, 44 bin the closed position on the membrane 18. Accordingly, the resonant frequency also changes in such a way that the oscillations occurring during operation of the associated internal combustion engine, not shown, lie outside the resonant frequency of the diaphragm 18 in the closed position.It can also be seen in FIG. 2 that the membrane supporting structure 32 has a planar supporting structure contact surface 46 which is oriented parallel to the contact surface 24 and is set back by the length L with respect to the contact surface 24 of the gas outlet section 22, as viewed in the flow direction and the direction of extent of the opening cross section 26. In the present case, the supporting web is set back by 0.5 mm, wherein the cross-sectional width Q (cf. FIG. 3 ) of the gas outlet section 22 is 10 mm.In the second embodiment shown in FIG. 4, the planar support structure contact surface 46 is set back with respect to the contact surface 24 by the length L of 1 mm.In the following, the same reference numerals are used for further embodiments for identical or at least functionally identical elements as for the description of the first embodiment. Only the part of the pressure limiting valve 10 relevant to the invention with the gas outlet section 22 is shown below. Moreover, the embodiments can be designed in particular as the first embodiment described above or alternatively within the scope of protection defined by the claims.FIG. 4 shows a second embodiment of a pressure limiting valve 10 in a representation analogous to FIG. 3. In this embodiment, the membrane supporting structure 32 is formed by two ribs 42 in the form of supporting webs which are oriented perpendicularly to one another and thus form a supporting cross 48. The ribs 42 are thus likewise formed as supporting webs in the sense of the invention and also in this embodiment integrally with the circumferential wall 36.In this embodiment, the membrane 18 (not shown) is divided into four partial surfaces in the closed state, whereby the ability of the membrane to oscillate is significantly reduced. Accordingly, the resonant frequency also changes considerably.The supporting webs shown in FIGS. 3 and 4 have a width B perpendicular to the main extent of the respective supporting webs which is approximately 10% of the cross-sectional width Q of the gas outlet section 22. The width B is thus 1 mm here. Overall, the flow in the gas outlet section 22 is therefore only slightly influenced, since the flow cross section is only insignificantly reduced by the supporting webs.FIG. 5 shows a third embodiment of a pressure limiting valve 10 not according to the invention in a representation analogous to FIG. 2, the diaphragm 18 being shown here in an open position. The diaphragm 18 has a position inclined by the angle α with respect to a plane perpendicular to the direction of extension of the opening cross section 26. The contact surface 24 is inclined at a corresponding angle α with respect to the plane perpendicular to the direction of extension. Accordingly, the diaphragm 18 can be moved into the closed position by displacement in a closing direction running parallel to the direction of extension and then simultaneously comes to bear with its circumference against the contact surface 24. The angle α is 3° in the present case. It has been found that even due to the mere inclination of the membrane 18 with respect to a plane perpendicular to the direction of extension, a change in the resonant frequency is effected and thus the acoustic behavior of the membrane 18 can be positively influenced. For the sake of completeness, it is pointed out that the embodiment according to FIG. 5 can also be combined with the previously described embodiments in order to further improve the acoustic behavior in the closed position.FIGS. 6 and 7 show a fourth and fifth embodiment of a pressure limiting valve 10 not according to the invention in a representation analogous to FIG. 2, wherein the diaphragm 18 in these embodiments has a curved position in each case.In FIG. 6, the membrane 18 is shown in a closed position. The contact surface 24 is indeed planar in cross section in the region of the respective outer edge, i.e. the edge extends, viewed in the purely radial direction, in each case exactly perpendicular to the direction of extent of the opening cross section 26. In the circumferential direction, however, the contact surface 24 has an inclination, so that in each case over half the circumference a uniformly increasing and a uniformly decreasing course results. Independently of the fixing of the membrane 18, this results in a double curvature in the radial direction in the closed position of the membrane 18, which is clearly recognizable in FIG. 6. The higher the inherent rigidity of the diaphragm 18, the further the curvature migrates in the radial direction toward the center of the opening cross section 26.The same applies to the fifth embodiment shown in FIG. 7, according to which the diaphragm plate 16 prestresses the diaphragm 18 with a curved surface on account of its asymmetric geometry. Accordingly, the diaphragm 18 has a biased and curved surface in both the open and closed positions, whereby the vibration capability can be sufficiently reduced to counteract acoustic anomalies during operation of an internal combustion engine.The thickness d of the membrane 18, which is entered by way of example in FIG. 7, is constant over the entire surface 50 above the gas outlet section 22 in all embodiments. However, it can also be designed in varying fashion.FIG. 8 shows a further embodiment of a circumferential wall 34 of a pressure limiting valve not according to the invention in a view analogous to FIG. 3 ; in this embodiment, only simple ribs 42 are formed as membrane supporting structure 32, which extend inward in the radial direction from the inner circumferential wall 36. In this embodiment, the support structure contact surfaces 46 of the ribs 42 are arranged in the same plane as the contact surface 24. As a result, the diaphragm 18, which is not shown in FIG. 8, is supported over its full surface both on the contact surface 24 and on the support structure contact surfaces 46, so that the region of the diaphragm 18 that can oscillate is reduced by the radial extent of the ribs 42. With such an embodiment, the acoustic properties of a pressure limiting valve 10 could already be improved considerably.For the sake of completeness, it is pointed out that, even in an embodiment as shown in FIG. 8, the supporting structure contact surfaces 46 can be offset with respect to the outer contact surface 24. However, it is important that the diaphragm 18, not shown in FIG. 8, comes to rest at least partially with the support structure contact surfaces 46 in the closed position, so that the oscillation behavior of the diaphragm 18 (not shown) thereby changes.FIGS. 9 and 10 show a further embodiment in a detail in a view analogous to FIG. 2. In FIG. 9, the membrane 18 is almost in the closed position, i.e. it is just not yet resting on the contact surface 24, so that gas can still flow through a small gap between membrane 18 and the contact surface 24 according to the arrow 56 into the opening cross section 26 and can flow downward along the direction of extension in the direction of a base section 54. In the region of the bottom section 54, the gas flows radially out of the opening cross section 26 again and is fed to an outlet line, not shown in any more detail, which is shown schematically by the arrow 58.As can be seen from a combination of FIGS. 9 and 10, in this embodiment a stamp-like central web 52 serving as a membrane supporting structure 32 is formed, which extends from the base section 54 upwards in the direction of the contact surface 24, so that in a region which the membrane 18 reaches in the closed position, a central web contact surface 60 of the membrane supporting structure 32 is formed, with which the membrane 18 at least partially comes into contact in the closed position.In the embodiment shown in FIGS. 9 and 10, the central web contact surface 60 has a rectangular basic shape and a planar surface which is oriented perpendicularly to the direction of extent of the central web 52. For the sake of completeness, it is pointed out that the shape can also be square, round, cruciform, star-shaped or any other shape. Furthermore, it is pointed out that the surface can also be configured as curved as desired instead of planar, in particular in such a way that the curvature is adapted to the curvature of the membrane 18 in the closed position. In the embodiment shown, the central web 52 is integrally formed with the bottom portion 54. It is also possible to produce one or more central webs 52 separately and to connect them firmly to a base section 54 or another suitable element of the opening cross section 26.List of reference characters10 Pressure limiting valve 12 Housing 14 Housing cover 16 Diaphragm plate 18 Diaphragm 18' Diaphragm according to the prior art 20 Gas inlet section 22 Gas outlet section 24 Contact surface 26 Opening cross section 28 Restoring element 30 Helical spring 32 Diaphragm supporting structure 34 Circumferential wall 36 Inner circumferential wall 38 First contact point 40 Second contact point 42 Rib 44 Partial surface 46 Supporting structure contact surface 48 Supporting cross 50 Surface 52 Central web 54 Base section 56 Arrow 58 Arrow 60 Central web contact surface

Claims

Pressure limiting valve having a gas inlet section (20), a gas outlet section (22) and a membrane (18) arranged between the gas inlet section (20) and the gas outlet section (22), which membrane is arranged so as to be adjustable as a function of pressure between at least one open position and one closed position, wherein the membrane (18) comes to bear in the closed position with a contact surface (24) upstream of an opening cross section (26) of the gas outlet section (22), wherein a membrane supporting structure (32) is formed or arranged in the opening cross section (26) of the gas outlet section (22), with which membrane supporting structure (18) comes to bear at least partially additionally in the closed position, wherein the membrane supporting structure (32) comprises at least one rib (42) extending from an inner circumferential wall (36) of the gas outlet section (22) radially into the opening cross section (26), which is designed as a supporting web and extends from a first contact point (38) of the inner circumferential wall (36) to a second contact point (40) of the inner circumferential wall (36), and / or the membrane supporting structure (32) comprises at least one central web (52) which extends at least partially in the direction of extent of the opening cross section (26) and runs through the central axis of a circular opening cross section, characterized in that the membrane supporting structure (32) is arranged or designed such that it is set back with respect to the contact surface (24), as viewed in the flow direction.Pressure limiting valve according to the preceding claim, characterized in that two supporting webs are arranged in an x-shape.Pressure limiting valve according to one of the two preceding claims and having at least one membrane supporting structure (32) which is designed as a rib (42), characterized in that the width (B) of at least one rib (42), as viewed perpendicularly to the main direction of extent of the rib (42), is between 1% and 20% of the cross-sectional width (Q) of the gas outlet section (22).Pressure limiting valve according to one of the preceding claims, characterized in that the membrane supporting structure (32) is formed integrally with the inner circumferential wall (36) of the opening cross section (26) of the gas outlet section (22) and / or the membrane supporting structure (32) is formed integrally with another region of the opening cross section (26) of the gas outlet section (22).Pressure limiting valve according to one of the preceding claims, characterized in that the diaphragm (18) is fixed in an outer region between a housing (12) and a housing cover (14) and is arranged in an inner region within a separately produced diaphragm plate (16), wherein a restoring element (28) is arranged between the diaphragm plate (16) and the housing (12) or housing cover (14), said restoring element producing an opening force counteracting the movement of the diaphragm (18) into the closed position.Pressure limiting valve according to one of the preceding claims, characterized in that the diaphragm (18) has an at least partially curved position in the region adjoining the opening cross section (26), at least in the closed position, and / or in that the diaphragm (18) is arranged in an open position at an inclination with respect to the perpendicular to the direction of extent of the opening cross section (26).Pressure limiting valve according to one of the preceding claims, characterized in that the contact surface (24) is of planar design and has an angle between 0° and 5° with respect to a plane perpendicular to the direction of extent of the opening cross section (26).

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