Respiratory flow sensor

Abstract

To provide a respiratory flow sensor which has a compact design and can be produced easily and with high quality.SOLUTION: A respiratory flow sensor 11 comprises: a flow tube 12 having a longitudinal axis 14, a first flow tube portion 21 and a second flow tube portion 41; a flow resistor 61 arranged in a flow channel 13 between the first flow tube portion 21 and the second flow tube portion 41; and two connection portions 32, 52 for taking in a pressure difference generated by the flow resistor 61. The first connection portion 32 the first flow tube portion 21 via a first connection line and is provided in the first flow tube portion 21. The second connection portion 52 communicates with the second flow tube portion 41 via a second connection line and is provided in the second flow tube portion 41. The connection portions 32, 52 respectively have connection line portions 33, 53 which extend essentially parallel to the longitudinal axis 14 of the flow tube 12. The openings 35, 55 of the connection portions 32, 52 are oriented in the same direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a respiratory flow sensor, a respiratory adapter, and a method for manufacturing a respiratory flow sensor. [Background technology]

[0002] Respiratory flow sensors, also called differential pressure flow sensors, flow measurement sensors, or flow sensors, are placed between the tubing leaving the ventilator or anesthesia machine and the tubing supplied to the patient.

[0003] A respiratory flow sensor is known from U.S. Pat. No. 4,403,514 A, which comprises a flow tube having a longitudinal axis, a first flow tube section, and a second flow tube section, and a tube connection for a tube in the region of the free end. A flow resistor is arranged in the flow tube between the first and second flow tube sections. Radially protruding connections are also provided for incorporating the pressure difference generated by the flow resistor. These connections are provided with connecting tubes that can be connected to a measuring device. The connection is provided on the first flow tube section and leads to the first flow tube section via a first connecting line. A further connection is provided on the second flow tube section and leads to the second flow tube section via a second connecting line.

[0004] A drawback of this known solution is that the connecting lines arranged at the connections can break, which under certain circumstances can lead to falsified measurement results.

[0005] A respiratory flow sensor is known from CH 701 755 B1, which includes a flow tube having a longitudinal axis, a first flow tube section, and a second flow tube section. A flow resistor is disposed within the flow tube between the first and second flow tube sections. A connection is provided for incorporating a pressure difference generated by the flow resistor. The first connection is connected to the first flow tube section via a first connecting line, and a further connection is connected to the second flow tube section via a second connecting line. Both connections are provided on the first flow tube section. Each connection has a connecting line section that extends parallel to the longitudinal axis of the flow tube. The openings of the connections are oriented in the same direction.

[0006] The drawback of this known solution is that not only do radially, i.e. outwardly projecting flange extensions have to be provided to form the connecting lines from the connecting parts to the corresponding flow tube parts, but also that complex structural and manufacturing measures are required in the design of the sealing means to ensure a sealed connection, which is the only way to prevent air short circuits, which leads to serious errors in the measurement results when using the airflow sensor.

[0007] DE 20 2017 102 703 U1 discloses a flow sensor having a flow tube with a longitudinal axis, a first tube element, and a second tube element. The flow sensor further includes a flow resistor disposed within the flow tube between the first and second tube elements. Extension tubes for incorporating a pressure difference generated by the flow resistor are disposed on the tube elements, with the first extension tube leading into the first tube element and the further extension tube leading into the second tube element. The first extension tube is disposed on the first tube element, and the further extension tube is disposed on the second tube element.

[0008] The drawback of this solution is that the extension tube projects essentially radially from the flow sensor, and as a result the measuring tube arranged therein also projects essentially radially during use, which results in the flow sensor taking up a relatively large amount of space during use, which makes handling the flow sensor cumbersome for the user.

[0009] A respiratory flow sensor is known from US Pat. No. 6,585,662 B1 which, in terms of its structural design, is almost identical to the respiratory flow sensor according to CH Pat. No. 701 755 B1, but has a much more practical design. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] U.S. Patent No. 4,403,514 [Patent Document 2] Swiss Patent No. 701755 [Patent Document 3] German Utility Model Registration No. 202017102703 [Patent Document 4] U.S. Patent No. 6,585,662 Summary of the Invention [Problem to be solved by the invention]

[0011] It is therefore an object of the present invention to create a respiratory flow sensor that does not have at least some of the above-mentioned drawbacks, has a very compact design and can be manufactured easily and with high quality. [Means for solving the problem]

[0012] This object is achieved by the features of the independent claims. Advantageous further developments are set out in the drawings and in the dependent claims.

[0013] According to the present invention, a respiratory flow sensor comprises a flow tube having a longitudinal axis, a first flow tube section, and a second flow tube section, a flow resistor disposed within the flow tube between the first and second flow tube sections, and a connection section for incorporating a pressure difference generated by the flow resistor. The first connection section communicates with the first flow tube section via a first connecting line. The further connection section communicates with the second flow tube section via a second connecting line, each of the connection sections having a connecting line section of the connecting line extending essentially parallel to the longitudinal axis of the flow tube, with the openings of the connection sections facing in the same direction. The first connection section is provided on the first flow tube section, and the further connection section is provided on the second flow tube section.

[0014] In this context, the term "essentially parallel to the longitudinal axis of the flow tube" is understood to mean, on the one hand, a mathematically defined parallel alignment with this longitudinal axis, but also an alignment that deviates therefrom by a few degrees.

[0015] The two connections of the respiratory flow sensor itself are advantageously aligned essentially parallel to one another so that the respiratory flow sensor can be made narrow.

[0016] Each flow tube section is provided with a connection for incorporating the pressure difference generated by the flow resistance, and a corresponding connecting line leads to the interior of that flow tube section. Therefore, when the flow tube sections are joined together, care must only be taken to seal the flow passages within the flow tube, so that the individual parts of the respiratory flow sensor can be designed to be simpler in terms of structure and can be easily joined together. Additional air guidance within the connecting lines can be avoided, which ensures and further improves measurement accuracy compared to previously known respiratory flow sensors.

[0017] The connecting lines are advantageously designed to be seamless, in other words each connecting line has no seam from the opening of the connecting part to the mouth of the respective flow tube part, which makes it possible to avoid adverse effects on the measurement and further improves the accuracy of the measurement.

[0018] The connection for incorporating the pressure difference generated by the flow resistance can be located close to the outside of the respiratory flow sensor housing while still ensuring a secure connection of the connecting tubing, allowing for a very compact design of the entire respiratory flow sensor.

[0019] The respiratory flow sensor preferably comprises two housing portions, a first flow tube portion and a second flow tube portion, which allows for easy assembly of the respiratory flow sensor.

[0020] The respiratory flow sensor also preferably comprises or is itself an injection-molded part, which can be economically produced, especially in large quantities, and can be easily assembled as required.

[0021] More preferably, the respiratory flow sensor is made from a plastic suitable for medical use, thereby eliminating the need for additional coatings within the flow tube, for example.

[0022] Preferably, the connecting lines each have further connecting line sections which extend at least partially straight and which intersect with connecting line sections which extend essentially parallel to the longitudinal axis of the flow tube, which allows for a structurally simple design of the connecting lines.

[0023] Preferably, the at least partially linear further connecting line section intersects the connecting line section that runs essentially parallel to the longitudinal axis of the flow tube at an angle of 40° to 70°, thereby ensuring good air guidance and allowing for easy production of the airflow sensor, especially as an injection-molded part.

[0024] Preferably, the first flow tube section has an essentially cylindrical portion and a radially expanding portion, the radially expanding portion expanding toward the open end of the first flow tube section, so that the second flow tube section can be positioned over the first flow tube section in a simple manner.

[0025] Alternatively or additionally, the second flow tube section has an essentially cylindrical portion and a radially expanding portion, the radially expanding portion expanding toward the open end of the second flow tube section, such that the first flow tube section can be easily positioned on the second flow tube section, and the two flow tube sections can be positioned in a simple manner to be sealed to one another.

[0026] In particular, the open ends of the first and second flow tube sections are each provided with a radially protruding flange having a contact surface, so that the diameter of this area is larger, and this arrangement is simplified with the help of two contact surfaces of the two flow tube sections.

[0027] Preferably, on the radially extending portion of the first flow tube section there is a first connection recess for at least partially receiving the further connection portion of the second flow tube section, so that the further connection portion of the second flow tube section can be easily placed in this first connection recess, thereby reducing the size of the respiratory flow sensor and making available the most compact respiratory flow sensor possible.

[0028] In particular, the first connection recess is arranged on a radially protruding flange of the first flow tube section, which has improved stability in the region of the radially protruding flange, and as a result, the first connection recess may likewise have improved stability or strength.

[0029] Advantageously, on the radially extending portion of the first flow tube section there is a first support structure for supporting the further connection part of the second flow tube section, so that this further connection part has an enlarged contact surface and is therefore received in a mechanically more stable manner and is, for example, less likely to break off.

[0030] Advantageously, the further connection part of the second flow tube part has a support part by means of which the further connection part can advantageously abut in the first connection recess on the radially extending part of the first flow tube part, and is thus stably held in the connection recess, which further prevents the further connection part from breaking, for example due to external mechanical loads.

[0031] Alternatively or additionally, a further connection recess is present on the radially extending portion of the second flow tube section for at least partially receiving the first connection portion of the first flow tube section, so that the first connection portion of the first flow tube section can be easily positioned within this second connection recess, thereby further reducing the size of the respiratory flow sensor and making available the most compact respiratory flow sensor possible.

[0032] In particular, the second connection recess is provided on a radially protruding flange of the second flow tube section, which has improved stability in the region of the radially protruding flange, so that the second connection recess may likewise have improved stability or strength.

[0033] Advantageously, there is a further support structure on the radially extending portion of the second flow tube section for supporting the first connection part of the first flow tube section, so that this connection part has improved mechanical stability, e.g. does not break.

[0034] Advantageously, the first connecting part of the first flow tube part has a support part by means of which the connecting part can advantageously abut against a second connecting recess on the radially extending part of the second flow tube part, and the first connecting part is thus stably held in the connecting recess, which can further prevent the first connecting part from breaking due to, for example, external mechanical loads.

[0035] Preferably, the further connecting line section of one connecting line that runs at least partially linearly intersects the connecting line section of the first connecting line that runs essentially parallel to the longitudinal axis of the flow tube at an angle of 48° to 62°, which allows for easy production of the respiratory flow sensor, especially as an injection-molded part, and ensures good air guidance, as well as low reworking efforts, for example when removing the respiratory flow sensor.

[0036] Particularly preferably, the further connecting line section of the connecting line, which runs at least partially linearly, intersects the connecting line section of the connecting line running essentially parallel to the longitudinal axis of the flow tube at an angle of 52° to 58°, which allows the respiratory flow sensor to be optimally constructed in addition to the above-mentioned advantages in terms of stability and material requirements for manufacturing it.

[0037] Preferably, the further connecting line section of the other connecting line, which runs at least partially linearly, intersects the connecting line section of the other connecting line, which runs essentially parallel to the longitudinal axis of the flow tube, at an angle of 130° to 160°, which ensures good air guidance while allowing for a simple manufacture of the airflow sensor, in particular as an injection-molded part.

[0038] Preferably, the further connecting line section of the other connecting line, which runs at least partially linearly, intersects with the connecting line section of the other connecting line which runs essentially parallel to the longitudinal axis of the flow tube at an angle of 138° to 152°, which allows for easy production of the respiratory flow sensor, especially as an injection-molded part, and ensures good air guidance, as well as low reworking efforts, for example when removing the respiratory flow sensor.

[0039] Particularly preferably, the at least partially linearly extending further connecting line section of the other connecting line intersects the connecting line section of the other connecting line that extends essentially parallel to the longitudinal axis of the flow tube at an angle of 142° to 148°. In this way, the respiratory flow sensor can be optimally constructed, in addition to the above-mentioned advantages in terms of stability and material requirements for manufacturing it.

[0040] Preferably, the first connector is arranged adjacent to the further connector, so that both connectors are arranged in the same area of ​​the flow tube, thereby preventing the connecting tube from buckling.

[0041] Preferably, the first connection portion is arranged adjacent to and at a distance from the further connection portion, so that the connection tube can be easily connected to the respective connection portion.

[0042] Preferably, the first connecting portion is at least partially provided on the outer jacket surface of the first flow tube portion and is therefore located outside the housing of the respiratory flow sensor. This allows the respiratory flow sensor to be easily manufactured and ensures an absolutely sealed connection between the first connecting portion and the first flow tube portion. Additional groove / comb structures in the area of ​​the additional connecting line portion can be omitted.

[0043] Alternatively or additionally, the further connection section can be at least partially arranged on the jacket surface of the second flow tube section, thus outside the housing of the respiratory flow sensor. This ensures an absolutely sealed connection between the second connection section and the second flow tube section. The additional groove / comb structure in the area of ​​the further connection line section can be omitted. Thus, the two flow tube sections can be joined together in a simple process step, the flow resistance is precisely positioned within the flow tube, and an absolutely sealed connection between the two flow tube sections is ensured.

[0044] Preferably, a tool opening for removing a forming tool for forming the further connection line section of the connecting line and a closing element for closing the tool opening are provided, with a first closing element for closing the further connection line section of the first connecting line preferably being provided on the first flow tube section, and a second closing element for closing the further connection line section of the second connecting line preferably being provided on the second flow tube section. This facilitates the manufacture of the respiratory flow sensor. When the tool opening is closed, air guidance in the corresponding connecting line is ensured without air short-circuiting.

[0045] Preferably, the first closure element is pivotally mounted to the first flow tube section via a hinge, preferably a flexible hinge. Preferably, the second closure element is pivotally mounted to the second flow tube section via a hinge, preferably a flexible hinge. Thus, the closure elements are constrainedly arranged on their respective components. As a result, the closure elements are available during the entire assembly of the respiratory flow sensor and can be provided in an optimized manner for closing tool openings as needed or during the manufacturing process of the respiratory flow sensor.

[0046] The closure element advantageously consists of a material suitable for medical applications, in particular a plastic suitable for medical applications. If the corresponding flow tube section is made of the same material or a material that is compatible with regard to the connection technology, the tool opening can therefore be closed in a simple working step.

[0047] The first and / or second closure elements can be designed as plugs which allow the corresponding tool openings to be closed in a simple process step.

[0048] Preferably, groove / comb structures are provided on the tool opening and / or closure element, which interlock when brought together, thereby ensuring a high degree of tightness of the closure.

[0049] Preferably, the closure element is fixed to the respective flow tube section by means of a sealing connection, particularly preferably by means of ultrasonic welding, in order to close the tool opening, thereby ensuring absolute tightness of the closure.

[0050] In alternative embodiments, the closure elements for closing the tool openings on the respective flow tube sections are secured by a type of welding other than ultrasonic welding, by a snug fit, or by adhesive bonding.

[0051] In a further alternative embodiment, for example, two-component solutions are provided in the manufacture of a respiratory flow sensor, at least one of which consists of or is coated with a softer plastic or a plastic with adhesive properties, for example in the area of ​​the contact surfaces, so that when the corresponding parts are brought together, they are directly sealed to each other.

[0052] Such a two-component solution is suitable for components that are to be connected to one another, especially components that are to be sealed together, during the manufacture of a respiratory flow sensor.

[0053] The respiratory adapter according to the present invention comprises at least one respiratory flow sensor having at least one of the aforementioned features and at least one connecting tube for connecting one of the connecting portions of the respiratory flow sensor to a measuring device to create a fluid connection from the measuring device to the respiratory flow sensor, the fluid connection being formed seamlessly and directly to one of the flow tube portions of the respiratory flow sensor.

[0054] Advantageously, the measurement device is designed to measure the pressure difference across the respiratory flow sensor.

[0055] This respiratory adapter is easy to use and has the advantages described herein in connection with the respiratory flow sensor.

[0056] In this context, the term "fluid connection" is understood to mean a flowable and optionally sealed connection for a fluid, such as air, from an entry point to an exit point.

[0057] Advantageously, a connection tube is provided at each connection of the respiratory flow sensor, which can be connected to a measuring device. To simplify the use of the respiratory adapter for the user, the connection tubes may be optically, for example color- and / or tactilely different.

[0058] Preferably, the respiratory adapter comprises at least one ventilation tube and a mouthpiece supplied to the patient, the at least one ventilation tube connecting the mouthpiece to at least one respiratory flow sensor, thereby creating an easy-to-use respiratory adapter.

[0059] Further advantageously, a further ventilation tube is provided which is also connected to at least one breathing sensor and can be connected to a ventilator or intensive care unit, so that the user has an easy-to-use breathing adapter.

[0060] The method according to the invention for manufacturing a respiratory flow sensor is characterized by the following steps:

[0061] By molding the first flow tube portion and the second flow tube portion, respectively, in a manufacturing tool mold, the corresponding connection line portion and further connection line portion of the connection line are formed by a slider as a molding tool and / or by a pin as a molding tool (step a)).

[0062] Alternatively or additionally, the further connection line section of the corresponding connection line is formed by means of a pin as a forming tool (step a)).

[0063] The forming tools are disposed or can be disposed in respective production tool molds, which allows for easy manufacturing of the first flow tube portion and the second flow tube portion.

[0064] The first flow tube section and the second flow tube section are demolded from their respective production tooling dies (step b)).

[0065] A molding tool designed as a slider or pin significantly simplifies the release of the first and second flow tube sections from their respective production tool dies.

[0066] The first and second flow tube sections are aligned axially and angularly relative to each other (step c)), which ensures accurate alignment of these sections relative to each other and therefore full functionality of the respiratory flow sensor.

[0067] A sealing connection between the first flow tube section and the second flow tube section (step d)). Sealing connections include, as a non-exhaustive list, welding, especially ultrasonic welding, a snug fit, an adhesive connection, or a two-component solution.

[0068] Advantageously, the tool openings at the respective connection points of the respiratory flow sensor are sealed by ultrasonic welding, which ensures air guidance in the corresponding connection lines without air short circuits.

[0069] Further advantages, features and details of the invention will become apparent from the following description in which exemplary embodiments of the invention are described with reference to the drawings.

[0070] The list of reference symbols, as well as the technical content of the claims and drawings, are part of this disclosure. The figures are described in a consistent and comprehensive manner. The same reference symbols indicate corresponding components, and reference symbols with different symbols indicate functionally identical or similar components. [Brief explanation of the drawings]

[0071] [Figure 1] 1 shows a perspective view of a first embodiment of a respiratory flow sensor according to the present invention; [Figure 2] 2 shows an exploded perspective view of the respiratory flow sensor according to FIG. 1. [Figure 3] 2 shows a first flow tube section of the respiratory flow sensor according to FIG. 1 in a side view. [Figure 4] 4 shows the first flow tube section according to FIG. 3 in a longitudinal section. [Figure 5] Detail section X of FIG. 4 is shown. [Figure 6] 2 shows a side view of a second flow tube section of the respiratory flow sensor according to FIG. 1; [Figure 7] 7 shows the second flow tube section according to FIG. 6 in a longitudinal section. [Figure 8] A detailed cross section Y of FIG. 7 is shown. [Figure 9] 1 to 8 in a perspective view. FIG. [Figure 10] 10 shows a side view of a first flow tube portion of a respiratory flow sensor according to a second embodiment. [Figure 11] 11 shows a first flow tube section according to FIG. 10 in a longitudinal section. [Figure 12] 10 shows a side view of a second flow tube section of a respiratory flow sensor according to a second embodiment. [Figure 13] 13 shows the second flow tube section according to FIG. 12 in a longitudinal section. [Figure 14] 11 and 13 show detailed cross sections Z. [Figure 15] 10 shows a longitudinal cross-sectional view of a first flow tube portion of a respiratory flow sensor according to a third embodiment. [Figure 16] 10 shows a longitudinal cross-sectional view of a second flow tube section of a respiratory flow sensor according to a third embodiment. [Figure 17] 1 shows a perspective view of a further embodiment of a respiratory flow sensor according to the present invention; [Figure 18] 18 shows a first flow tube section according to FIG. 17 in a perspective view. [Figure 19] 18 shows a second flow tube section according to FIG. 17 in a perspective view. [Figure 20] 11 shows a further perspective view of the respiratory flow sensor according to FIG. DETAILED DESCRIPTION OF THE INVENTION

[0072] The first embodiment of respiratory flow sensor 11 shown in FIGS. 1 to 8 is an injection molded product, and respiratory flow sensor 11 is made of plastic.

[0073] As shown in Figures 1 and 2, the respiratory flow sensor 11 has a flow tube 12 having a longitudinal axis 14 and a first flow tube portion 21 and a second flow tube portion 41, and in the region of two free ends 16 and 18 have tube connections 17 and 19 for artificial ventilation tubing, respectively.

[0074] On the tube connection 17, a respiration tube is placed, which leads to a mouthpiece or respiration mask, not shown, which is placed on the patient for respiration, and on the other tube connection 19, a respiration tube is placed which leads to a ventilator.

[0075] A flow resistor 61 is disposed in the flow tube 12 forming the flow path 13 between the first flow tube section 21 and the second flow tube section 41, and is configured as a diaphragm flap. The flow resistor 61 is provided with a circumferential recess 62 which interacts with a cam 30 provided on the first flow tube section 21, thereby ensuring correct alignment of the flow resistor 61 within the flow path 13 when the respiratory flow sensor 11 is assembled.

[0076] Instead of a protruding cam 30 and a interacting recess 62, the precise alignment of the flow resistance 61 in the flow path 13 and also of the first flow tube section 21 and the second flow tube section 41 may be ensured via adjustment means which may be provided on the outside, for example, and / or via a groove / comb structure.

[0077] The respiratory flow sensor 11 has two connections 32 and 52 for incorporating the pressure difference created by the flow resistance 61. The openings 35 or 55 of the connections 32 and 52 are oriented in the same direction, i.e., toward the free end 16 of the first flow tube section 21. The connections 32 and 52 are provided on the outer jacket surface of the respective flow tube sections 21 and 41 and are adjacent to and spaced apart from each other.

[0078] The first flow tube section 21 (see also, in particular, Figures 3-5) is the first housing part of the respiratory flow sensor 11. The first flow tube section 21 has an essentially cylindrical portion 22 and a radially expanding portion 26, resulting in a larger diameter in this region. In the essentially cylindrical portion 22, a guide element 23 is provided in the flow path section, which divides the flow path 13 in this region into two equal-sized portions and allows for targeted air guidance within the flow tube 12.

[0079] Similarly, the corresponding flow passage section in the radially expanding section 26 increases in size toward the open end 24 of the first flow tube section 21. This open end 24 is provided with a radially protruding flange 27 having a contact surface 29, resulting in an increased diameter in this region. When the respiratory flow sensor 11 is assembled, the contact surface 29 faces the second flow tube section 41. This flange 27 is provided with a first circumferential portion 28 of a groove / comb structure on the contact surface 29. In the region of the flange 27, the radially expanding section 26 has a first connection recess 27a supported by a first support structure 27b. Adjacent to the opening 55, a further connection section 52 of the second flow tube section 41 has a support portion 52a that, in the assembled state, fits tightly against or rests on the first connection recess 27a of the respiratory flow sensor 11 and is supported by the first support structure 27b.

[0080] The cam 30 protrudes from the contact surface 29 to precisely align the flow resistance 61 within the flow tube 12 when the respiratory flow sensor 11 is assembled.

[0081] A first connection 32 for introducing the pressure difference caused by the flow resistance 61 leads via a first connection line to the flow passage section of the first flow tube section 21. The first connection line has a connection line section 33 which extends essentially parallel to the longitudinal axis 14 of the flow tube 12 and a further connection line section 34 which extends partially straight and intersects the connection line section 33 which extends essentially parallel to the longitudinal axis 14 of the flow tube 12 at an angle α of 40° to 70°, preferably 48° to 62°, particularly preferably 52° to 58°. In this example, this angle α is 55°.

[0082] As an extension of this further connection line section 34 of the first connecting line, the first flow tube section 21 is provided with a first tool opening 36 for removing a forming tool for forming this further connection line section 34 and a first closure element 38 for closing this tool opening 36. The first closure element 38 is pivotably provided on the first flow tube section 21 via a hinge, here a flexible hinge 39 or a film hinge.

[0083] A groove structure 37 is formed around the first tool opening 36. A comb structure 40 is formed on the first closure element 38, which engages with the groove structure 37 when the first tool opening 36 is closed and ensures the sealing of the first tool opening 36 and thus the tightness of the first connection line during a welding process, in particular an ultrasonic welding process.

[0084] In FIG. 5, the first tool opening 36 is shown in a closed state.

[0085] The second flow tube section 41 (see also, in particular, Figures 6-8) is a second housing part of the respiratory flow sensor 11. The second flow tube section 41 has an essentially cylindrical section 42 that tapers outwardly towards the free end 18 and a radially enlarged section 46. The essentially cylindrical section 42 is provided with a guide element 43 in its flow passage section, which divides the flow tube 12 in this region into two equal-sized sections and allows for targeted air guidance within the flow tube 12. The free end 45 of the guide element 43 is set back relative to the free end 18 of the flow tube 12.

[0086] In the radially or outwardly enlarged portion 46, the corresponding flow passage portion also increases in size toward the open end 44 of the second flow tube portion 41. This open end 44 is provided with a radially protruding flange 47 with a contact surface 49 that faces the first flow tube portion 21 or its contact surface 29 when the respiratory flow sensor 11 is assembled. This flange 47 is provided with a second circumferential portion 48 of a groove / comb structure at the contact surface 49, which engages with the first circumferential portion 28 of the groove / comb structure and fuses therewith during welding, particularly ultrasonic welding. This ensures a simple sealing connection between the first flow tube portion 21 and the second flow tube portion 41. The complex multiple structures for the groove / comb structure or pressure surface, as proposed in CH 701 755 B1, are not necessary with the solution according to the present invention.

[0087] The flange 47 is provided with a receiving recess 51 offset from the contact surface 49, into which the flow resistor 61 is at least partially received. The cylindrical ring of the receiving recess 51 is provided with a hole 50 through which the cam 30 of the first flow tube section 21 passes during assembly of the respiratory flow sensor 11. This configuration not only allows for precise alignment of the flow resistor 61 within the flow path 13 during assembly of the respiratory flow sensor 11, but also, in combination with the groove / comb structures 28 and 48 on the flanges 27 and 47, allows for the placement of flow resistors of different thicknesses depending on the field of use or need. The respiratory flow sensor 11 is thus flexible in use and can be adapted to other types of flow resistors 61 without significant effort. The flow resistor 61 used is held between the first flow tube section 21 and the second flow tube section 41, in particular by being partially or completely glued, clamped, or otherwise held.

[0088] In the assembled state of the respiratory flow sensor 11, no flange pressure surfaces are formed on the flanges 27, 47. The connection between the first flow tube portion 21 as the first housing part of the respiratory flow sensor 11 and the second flow tube portion 41 as the second housing part of the respiratory flow sensor 11 is made solely by the groove / comb structures 28 and 48 formed on the flanges 27 and 47.

[0089] The radially widening portion 46 has, in the region of the flange 47, a further connection recess 47a supported by a further support structure 47b. The first connection part 32 of the first flow tube section 21 has, adjacent to the first closure element 38, a support part 32a which, in the assembled state, fits tightly against or rests on the further connection recess 47a of the respiratory flow sensor 11 and is supported by the support structure 47b.

[0090] A second connection 52 for introducing the pressure difference created by the flow resistance 61 leads via a second connection line to the flow passage section of the second flow tube section 41. The second connection line has a connection line section 53 which runs essentially parallel to the longitudinal axis 14 of the flow passage 13 and a further connection line section 54 which runs partly straight and intersects with the connection line section 53 at an angle β of 130° to 160°, preferably 138° to 152°, particularly preferably 142° to 148°. In this example, this angle β is 145°.

[0091] As an extension of this further connection line section 54 of the second connecting line, the second flow tube section 41 is provided with a second tool opening 56 for removing the forming tool for forming this further connection line section 54 and with a second closure element 58 for closing this tool opening 56. The second closure element 58 is pivotably provided on the second flow tube section 41 via a hinge, here a flexible hinge 59 or a film hinge.

[0092] A groove structure 57 is formed around the second tool opening 56. A comb structure 60 is formed on the second closure element 58, which engages with the groove structure 57 when the first tool opening 36 is closed and ensures the sealing of the second tool opening 56 and thus the tightness of the second connection line during a welding process, in particular an ultrasonic welding process.

[0093] In FIG. 8, the second tool opening 56 is shown in an open position.

[0094] To manufacture the respiratory flow sensor 11, the first flow tube section 21 is molded in a manufacturing tool mold, the connecting line section 33 is formed by a pin as a molding tool, and the further connecting line section 34 is formed by a slider as a molding tool. The first flow tube section 21 is then released from the manufacturing tool mold, for which purpose the slider is previously pulled from the first flow tube section 21.

[0095] Simultaneously, or with a time delay, the second flow tube portion 41 is formed in a further manufacturing tooling mold, the connecting line portion 53 is formed with a pin as a forming tool, and the further connecting line portion 54 is formed with a slider as a forming tool. The second flow tube portion 41 is then released from the manufacturing tooling mold, for which purpose the slider is previously withdrawn from the second flow tube portion 41.

[0096] Here, the tool openings 36, 56 can be closed by closure elements 38, 58, respectively.

[0097] The first flow tube section 21 and the second flow tube section 41 are now aligned with each other, specifically axially and with respect to their angular position relative to each other.

[0098] Next, the first flow tube portion 21 and the second flow tube portion 41 are sealingly connected to each other by ultrasonic welding in this embodiment.

[0099] 9 comprises a respiratory flow sensor 11, a connection tube 73 connecting the connection portion 32 of the respiratory flow sensor 11 to a measurement device 76 to create a first fluid connection from the measurement device 76 to the respiratory flow sensor 11, and a connection tube 74 connecting the connection portion 52 of the respiratory flow sensor 11 to the measurement device 76 to create a second fluid connection from the measurement device 76 to the respiratory flow sensor 11. The fluid connection is made directly to one of the flow tubing portions of the respiratory flow sensor 11 to provide a seamless connection.

[0100] The respiratory adapter 71 further comprises a first ventilation tube 77 and a mouthpiece 78 designed as a ventilation mask. The first ventilation tube 77 connects the mouthpiece 78 to the respiratory flow sensor 11. The respiratory adapter 71 further comprises a second ventilation tube 79 that connects the respiratory flow sensor 11 to the ventilator 72.

[0101] The measuring device 76 is designed to measure or record and process the pressure difference generated within the respiratory flow sensor 11. In this example, the measuring device 76 is incorporated into a ventilator 72 designed for the artificial ventilation of a patient.

[0102] In a second exemplary embodiment of a respiratory flow sensor shown in Figures 10-14, a first flow tube section 81 (see especially Figures 10 and 11) essentially differs from the first flow tube section 21 of the respiratory flow sensor 11 only in that it is made in several sections and has one connecting line. In this case, a connecting line section 83 emerging from an opening 85 of a connecting section 82 is not directly connected to a further connecting line section 84. The connecting line section 83 and the further connecting line section 84 each lead to an open end 86 of the first flow tube section 81. The connecting section 82 is further provided on the first flow tube section 81.

[0103] The first flow tube section 81 is designed in two parts, namely, the flow tube section 91 and the flow tube section 93, which are connected to each other by a sealed connection. Because the first flow tube section 81 consists of two parts, the structure of the connecting lines in this first flow tube section can be manufactured in a desired manner while ensuring simple manufacturing. Therefore, no manufacturing or tooling openings are required to mold the first flow tube section 81.

[0104] The configuration of the second flow tube section 101 of the second embodiment of the respiratory flow sensor (see in particular Figures 12 and 13) essentially corresponds to the second flow tube section 41 of the respiratory flow sensor 11. However, in the assembled state, this second flow tube section 101 has an air deflector 112 in the area opposite the connection section 82 of the first flow tube section 81, the cavity 113 of which opens into the free end 114 of the second flow tube section 101.

[0105] As shown in detail in FIG. 14 , when the first flow tube section 81 and the second flow tube section 101 are joined, the path of the first connecting line can be seen from the connection section 82 to the interior of the first flow tube section 81. The fluid is redirected within the cavity 113. The sealed connection between the first flow tube section 81 and the second flow tube section 101 in this deflection region is only provided at the contact sections 116 and 117. In this embodiment, the first connecting line is not formed seamlessly. However, the second connecting line of the second flow tube section 101 is still seamless.

[0106] The first flow tube section 121 (see FIG. 15) and the second flow tube section 141 (see FIG. 16) of the respiratory flow sensor according to the third embodiment differ only in the design of their connecting lines.

[0107] A first connection 132 for introducing a pressure difference caused by the flow resistance leads via a first connecting line to the flow channel section of the first flow tube section 121. The connecting line section 133 and the further connecting line section 134, which run essentially parallel to the longitudinal axis 124 of the flow tube, intersect at an angle γ of 130° to 160°, preferably 138° to 152°, particularly preferably 142° to 148°. In this example, this angle γ is approximately 147°. This angle γ was selected so that a forming tool designed as a slider can be easily pulled out when the first flow tube section 121 is demolded without the need for a tool opening for this purpose.

[0108] A second connection 152 for introducing the pressure difference caused by the flow resistance leads via a second connecting line to the flow channel section of the second flow tube section 141. The connecting line section 153 and the further connecting line section 154, which run essentially parallel to the longitudinal axis 124 of the flow tube, intersect at an angle δ of 40° to 70°, preferably 48° to 62°, particularly preferably 52° to 58°. In this example, this angle δ is 53°. This angle δ was selected so that a molding tool designed as a slider can be easily pulled out when the second flow tube section 141 is demolded without the need for a tool opening for this purpose.

[0109] The first connecting line and the second connecting line are each designed to be seamless.

[0110] In a further exemplary embodiment of a respiratory flow sensor 211 shown in Figures 17-20, the flow tube 212 has a longitudinal axis 214, a first flow tube section 221, and a second flow tube section 241. Here, the first flow tube section 221 (see in particular Figure 18) essentially differs from the first flow tube section 21 of the respiratory flow sensor 11 only in that the first closure element 238 is designed as a tube section 239 at the connection section 232. The first closure element 238 has a first tool opening 236 leading to a further connection line section 234, and the connection line section 233 emerging from an opening 235 of the connection section 232 is directly connected to the further connection line section 234. The first connection section 232 is further provided on the first flow tube section 221.

[0111] First flow tube section 221 is the first housing portion of respiratory flow sensor 211. First flow tube section 221 has an essentially cylindrical portion 222 and a radially expanding portion 226, resulting in a larger diameter in this region. In essentially cylindrical portion 222, a guide element 223 is provided in the flow path section, which divides flow path 213 in this region into two equal-sized portions and allows for targeted air guidance within flow tube 212.

[0112] In the radially expanding portion 226 of the first flow tube section 221, the corresponding flow channel section also increases in size towards the open end 224 of the first flow tube section 221 (see in particular FIG. 18 ). This open end 224 is provided with a radially protruding flange 227. In the radially expanding portion 226, in the region of the flange 227, there is a first connection recess 227a supported by a first support structure 227b. Adjacent to the opening 255, the further connection section 252 of the second flow tube section 241 has a support portion 252a which, in the assembled state, fits tightly against or rests on the first connection recess 227a of the respiratory flow sensor 11.

[0113] The configuration of the second flow tube section 241 of this exemplary embodiment of the respiratory flow sensor 211 (see in particular FIG. 19 ) essentially corresponds to the second flow tube section 41 of the respiratory flow sensor 11. However, this second flow tube section 241 has a closure element 258 designed as a tube section 259 on the second connection section 252. The closure element 258 has a second tool opening 256 that leads to a further connection line section 254, with the connection line section 253 emerging from an opening 255 of the second connection section 252 being directly connected to the further connection line section 254. The second connection section 252 is further provided on the second flow tube section 241.

[0114] The second flow tube section 241 also constitutes the second housing portion of the respiratory flow sensor 211. The second flow tube section 241 has an essentially cylindrical portion 242 that tapers outward toward the free end 218. The second flow tube section 241 has a radially enlarged portion 246 toward the open end 244. The essentially cylindrical portion 242 is provided with a guide element 243 in its flow passage, which divides the flow tube 212 into two equal-sized portions in this region and allows for targeted air guidance within the flow tube 212. The free end 245 of the guide element 243 is recessed relative to the free end 218 of the flow tube 212.

[0115] The radially widening portion 246 of the second flow tube section 241 has, in the region of the flange 247, a further connecting recess 247a supported by a further support structure 247b. The first connecting portion 232 of the first flow tube section 221 has, adjacent to the first closure element 238, a support portion 232a which, in the assembled state, fits tightly against or rests on the further connecting recess 247a of the respiratory flow sensor 11.

[0116] 20 shows the assembled respiratory flow sensor 211, with tooling openings 236 and 256 on tubing sections 239 and 259 shown closed, which were hermetically sealed in an ultrasonic welding process using an ultrasonic welding device.

[0117] <Additional Notes> [1] 1. A respiratory flow sensor comprising: a flow tube (12; 212) having a longitudinal axis (14; 124; 214), a first flow tube portion (21; 81; 121; 221), and a second flow tube portion (41; 101; 141; 241); a flow resistance (61) disposed within the flow tube (12; 212) between the first flow tube section (21; 81; 121; 221) and the second flow tube section (41; 101; 141; 241); a connection (32, 52; 82, 102; 132, 152; 232, 252) for introducing the pressure difference generated by the flow resistance (61); and the first connection part (32; 82; 132; 232) leads to the first flow tube part (21; 81; 121; 221) via a first connection line; a further connection (52; 102; 152; 252) leading via a second connecting line to a second flow tube section (41; 101; 141; 241); each of the connecting portions (32, 52; 232, 252) having a connecting line portion (33, 53; 83; 133, 153; 233; 253) extending essentially parallel to the longitudinal axis (14; 124; 214) of the flow tube (12; 212); The openings (35, 55; 85; 235, 255) of the connecting portions (32, 52; 82, 102; 132, 152; 232, 252) are oriented in the same direction; In the respiratory flow sensor, the first connection portion (32; 82; 132; 232) is provided on the first flow tube portion (21; 81; 121; 221); A further connection (52; 102; 152; 252) is provided on the second flow tube section (41; 101; 141; 241). A respiratory flow sensor comprising: [2] The connection lines each include: The respiratory flow sensor according to item [1] above, characterized in that it has further connecting line portions (34, 54; 84; 134, 154; 234, 254) which extend at least partially linearly and which intersect at a predetermined angle (α, β, γ, δ) with the connecting line portions (33, 53; 83; 133, 153; 233, 253) which extend essentially parallel to the longitudinal axis (14; 124; 214) of the flow tube (12; 212). [3] The respiratory flow sensor according to item [2] above, characterized in that the further connection line section (34; 154; 234; 254) of one of the connection lines, which extends at least partially linearly, intersects with the connection line section (33; 153; 233; 253) of the connection line, which extends essentially parallel to the longitudinal axis (14; 124; 214) of the flow tube (12; 212), at an angle (α) of 40° to 70°, preferably 48° to 62°, particularly preferably 52° to 58°. [4] The respiratory flow sensor according to the above [2] or [3], characterized in that the further connection line section (54; 134; 234; 254) of the other connection line, which extends at least partially linearly, intersects with the connection line section (53; 133; 233; 253) of the other connection line, which extends essentially parallel to the longitudinal axis (14; 124; 214) of the flow tube (12; 212), at an angle (β) of 130° to 160°, preferably 138° to 152°, particularly preferably 142° to 148°. [5] the first connection portion (32; 82; 132; 232) is arranged adjacent to the further connection portion (52; 102; 152; 252), Preferably, the respiratory flow sensor according to any one of [1] to [4] above, characterized in that the first connection portion (32; 82; 132; 232) is also positioned at a distance from the further connection portion (52; 102; 152; 252). [6] the first connection portion (32; 82; 132; 232) is at least partially provided on the outer jacket surface of the first flow tube portion (21; 81; 121; 221); and / or The respiratory flow sensor according to any one of the above [1] to [5], characterized in that the further connection portion (52; 102; 152; 252) is at least partially provided on the jacket surface of the second flow tube portion (41; 101; 141; 241). [7] the first flow tube section (21; 81; 121; 221) and / or the second flow tube section (41; 101; 141; 241) has an essentially cylindrical portion (22, 42; 222, 242) and a radially expanding portion (26; 226; 46, 246); the radially expanding portion (26; 226; 226; 46, 246) expands toward the open end (24, 224; 44, 244) of the respective first flow tube section (21; 81; 121; 221) or second flow tube section (41; 101; 141; 241); In particular, the respiratory flow sensor according to any one of the above [1] to [6] is characterized in that the open ends (24, 224; 44, 244) of the first flow tube section (21; 81; 121; 221; 221) and the second flow tube section (41; 101; 141; 241) are each provided with a radially protruding flange (27, 47; 227, 247) having a contact surface. [8] on the radially extending portion (26; 226) of the first flow tube portion (21; 81; 121; 221) there is a first connection recess (27a; 227a) for at least partially receiving a further connection portion (52; 102; 152; 252) of the second flow tube portion (41; 101; 141; 241), and / or The respiratory flow sensor according to [7] above, characterized in that on the radially extending portion (46; 246) of the second flow tube section there is a further connection recess (47a; 247a) for at least partially receiving the first connection portion (32; 82; 132; 232) of the first flow tube section (21; 81; 121; 221). [9] a tool opening (36, 56; 236, 256) for removing a forming tool for forming a further connection line section (34, 54; 234, 254) of the connection line, and a closure element (38, 58; 238, 258) for closing the tool opening (36, 56; 236, 256), a first closure element (38; 238) for closing the further connection line section (34; 234) of the first connection line is preferably provided on the first flow tube section (21; 221), A respiratory flow sensor according to any one of the above [2] to [5], characterized in that a second closing element (58; 258) for closing a further connection line portion (54; 254) of the second connection line is provided, preferably in the second flow tube portion (41; 241).

[10] the first closure element (38) is pivotally mounted to the first flow tube section (21) via a hinge, preferably a flexible hinge (39); and / or The respiratory flow sensor described in [9] above, characterized in that the second closure element (58) is pivotally mounted on the second flow tube portion (41) via a hinge, preferably a flexible hinge (59).

[11] a groove / comb structure (37, 40, 57, 60) is provided on the tool opening (36, 56; 236, 256) and / or on the closure element (38, 58; 238, 258), Preferably, the respiratory flow sensor according to [9] or

[10] above, characterized in that the closure element (38, 58; 238, 258) is fixed to the respective flow tube section (21, 41; 221, 241) by a sealing connection, particularly preferably by ultrasonic welding, in order to close the tool opening (36, 56; 236, 256).

[12] A respiratory adapter comprising at least one respiratory flow sensor (11) according to any one of the above [1] to

[11] , and at least one connection tube (73, 74) for connecting one of the connection portions (32, 52; 232, 252) of the respiratory flow sensor (11) to a measurement device (76) to create a fluid connection from the measurement device (76) to the respiratory flow sensor (11), A respiratory adapter, characterized in that the fluid connection is made seamlessly and directly to one of the flow tube sections (21; 81; 121; 221) of the respiratory flow sensor (11).

[13] At least one ventilation tube (77, 79) and a mouthpiece (78) are provided; The respiratory adapter according to

[12] above, characterized in that at least one artificial respiration tube (77) connects the mouthpiece (78) to at least one respiratory flow sensor (11).

[14] A method for manufacturing the respiratory flow sensor (11) according to any one of the above [1] to

[11] , a) forming the first flow tube section (21; 81; 121; 221) and the second flow tube section (41; 101; 141; 241) in a manufacturing tool mold, respectively, and the corresponding connection line sections (33 or 53; 83; 133 or 153; 233 or 253) and further connection line sections (34 or 54; 84; 134 or 154; 234 or 254) of the connection line are formed by a slider as a forming tool and / or by a pin as a forming tool; b) demolding the first flow tube portion (21; 81; 121; 221) and the second flow tube portion (41; 101; 141; 241) from their respective production tooling dies; c) axially and angularly aligning the first flow tube section (21; 81; 121; 221) and the second flow tube section (41; 101; 141; 221) with respect to one another; d) forming a sealed connection between the first flow tube section (21; 81; 121; 221) and the second flow tube section (41; 101; 141; 241); A method comprising: [Explanation of symbols]

[0118] 11 respiratory flow sensor, 12 flow tube, 13 flow path, 14 longitudinal axis of 12, 16 free end of 12, 17 tube connection portion, 18 free end of 12, 19 tube connection portion, 21 first flow tube portion, 22 cylindrical portion, 23 guide element, 24 open end of 21, 26 flared portion, 27 flange, 27a first connection recess, 27b first support structure, 28 first circumferential portion of groove / comb structure, 29 contact surface, 30 cam, 32 first connection portion, 32a support portion of 32, 33 connection line portion, 34 connection line portion, 35 opening of 32, 36 first tool opening, 37 groove structure, 38 first closure element, 39 flexible hinge, 40 comb structure, 41 second flow tube portion, 42 cylindrical portion, 43 Guide element, 44 open end of 21, 45 free end of 43, 46 enlarged portion, 47 flange, 47a further connection recess, 47b further support structure, 48 second circumferential portion of groove / comb structure, 49 contact surface, 50 hole, 51 receiving recess, 52 second connection portion, 52a support portion of 52, 53 connection line portion, 54 further connection line portion, 55 opening of 32, 56 second tool opening, 57 groove structure, 58 second closure element, 59 flexible hinge, 60 comb structure, 61 flow resistance, 62 recess of 61, α angle between 33 and 34, β angle between 53 and 54, 71 breathing adapter, 72 ventilator, 73 first connecting tube, 74 second connecting tube, 76 measuring device / ventilator, 77 first breathing tube, 78 Mouthpiece, 79, second ventilation tube, 81, first flow tube section, 82, first connection section, 83, connection line section, 84, further connection line section, 85, opening of 82, 86, open end of 81, 91, first flow tube section, 93, second flow tube section, 101, second flow tube section, 102, second connection section, 112, air deflector, 113, cavity of 112, 114, free end of 101, 116, contact section, 117, contact section, 121, first flow tube section, 124, longitudinal axis, 132, first connection section, 133, connection line section, 134, further connection line section, 141, second flow tube section, 152, second connection section, 153, connection line section, 154, further connection line section, 211, respiratory flow sensor, 212, flow tube, 213, flow path, 214 Longitudinal axis 218, free end 221 of 212, first flow tube portion 222, cylindrical portion 223Guide element 224, open end of 221, 226, widening portion 227, flange 227a, first connection recess 227b, first support structure 232, first connection portion 232a, support portion of 232, 233, connection line portion 234, further connection line portion 235, opening 236, first tool opening 238, first closure element 239, tube portion 241, second flow tube portion 242, cylindrical portion 243, guide element 244, open end 245, free end of 243, 246, widening portion 247, flange 247a, further connection recess 247b, further support structure 252, second connection portion 252a, support portion of 252, 253, connection line portion 254, further connection line portion 255, opening 256, second tool opening 258 Closure element, 259 tubular section, γ angle between 133 and 134, δ angle between 153 and 154.

Claims

1. a flow tube having a longitudinal axis, the flow tube including a first flow tube section and a second flow tube section; a flow resistance disposed within the flow tube between the first flow tube section and the second flow tube section; a first connection and a second connection for taking in the pressure difference created by the flow resistance; Equipped with the first connection portion communicates with the first flow tube portion through a first connection line; the second connection portion communicates with the second flow tube portion through a second connection line; the first connection line and the second connection line each include a tool opening and a closure element configured to fit into the tool opening; Respiratory flow sensor.

2. 2. The respiratory flow sensor of claim 1, wherein the first flow tube portion and the second flow tube portion are designed to be molded in a manufacturing tool mold, and the tool opening is configured to be releasable from a molding tool used to mold the corresponding connecting line.

3. The respiratory flow sensor of claim 2 , wherein the forming tool comprises a slider and / or a pin.

4. The respiratory flow sensor of claim 1 , wherein the closure element comprises a plug.

5. 5. The respiratory flow sensor of claim 4, wherein the closure element is hingedly disposed in the tool opening.

6. The respiratory flow sensor of claim 5 , wherein the hinge comprises a living hinge or a film hinge.

7. 10. The respiratory flow sensor of claim 1, wherein the tool opening has a groove structure, and the closure element has a comb structure configured to engage the groove structure to close the tool opening.

8. The respiratory flow sensor of claim 1 , wherein the closure element is configured to close the tool opening by a tight fit, adhesive, or welding.

9. The respiratory flow sensor of claim 1 , wherein the closure element is configured to close the tool opening by ultrasonic welding.

10. 2. The respiratory flow sensor of claim 1, wherein the first flow tube section and the second flow tube section include a sealed connection connecting the first flow tube section and the second flow tube section together axially and angularly.

11. 11. The respiratory flow sensor of claim 10, wherein the sealing connection comprises a welded or adhesive connection.

12. 11. The respiratory flow sensor of claim 10, wherein the sealed connection comprises an ultrasonic welded connection.

13. the first flow tube portion has a first radially protruding flange, a first circumferential groove / comb structure, and a first contact surface; the second flow tube portion has a second radially projecting flange, a second circumferential groove / comb structure, and a second contact surface; 11. The respiratory flow sensor of claim 10, wherein the sealing connection has the first circumferential groove / comb structure and the second circumferential groove / comb structure that allow the first flow tube section and the second flow tube section to connect at the first contact surface and the second contact surface.

14. the first flow tube section includes the first connecting portion on an outer surface thereof, has a first essentially cylindrical portion and a radially diverging portion terminating at the first contact surface; The second flow tube section includes the second connection portion on an outer surface thereof: a second essentially cylindrical portion and a radially extending portion terminating in said second contact surface; the second essentially cylindrical portion has a larger radius than the first essentially cylindrical portion of the first flow tube section; 14. The respiratory flow sensor of claim 13, wherein the radially expanding portion has a larger radius than the second essentially cylindrical portion.

15. 15. The respiratory flow sensor of claim 14, wherein the first essentially cylindrical portion and the second essentially cylindrical portion each include a guide element that divides the respective flow tube into two portions of equal size.

16. 15. The respiratory flow sensor of claim 14, wherein the first connection portion and the second connection portion each include an opening, and the openings of the first connection portion and the second connection portion are oriented in the same direction.

17. the first connecting line includes a first portion extending essentially parallel to the longitudinal axis of the flow tube, and a first further connecting line portion extending at least partially linearly and intersecting the first portion extending essentially parallel to the longitudinal axis at a first angle α; 2. The respiratory flow sensor of claim 1, wherein the second connecting line includes a second portion extending essentially parallel to the longitudinal axis of the flow tube, and a second further connecting line portion extending at least partially and intersecting the second portion extending essentially parallel to the longitudinal axis at a second angle β.

18. 18. The respiratory flow sensor of claim 17, wherein the first angle α is an acute angle and the second angle β is an obtuse angle.

19. 20. The respiratory flow sensor of claim 18, wherein the first angle α is between 40° and 70°.

20. 20. The respiratory flow sensor of claim 18, wherein the second angle β is between 130° and 160°.

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