DE102018204799A1 - Differential pressure flow sensor for ventilators with improved flow resistance with multi-part flap - Google Patents

Abstract

A differential pressure flow sensor (44) comprises a sensor housing (46) which defines a flow channel (52) passing through the sensor housing (46), through which fluid can flow through a flow path (S), - a flow resistance arrangement (72; 72 '; 72 ") arranged in the flow channel (52) and axially on both sides of the flow resistance arrangement (72; 72 '; 72") Druckfassungsformationen (56a, 58a), wherein the flow resistance arrangement (72) comprises: - a fixed outside of the flow channel (52) Festlegeabschnitt ( 72a) formed to define the drag assembly (72) on the sensor housing (46) and a plurality of relatively movable flap disposed within the flow channel (52) which are movable relative to the securement portion between an unloaded rest position and one by Aussere force due to fluid flow along the flow path (S) deflected deflection According to the invention, it is provided that the fixing section (72a) surrounds the flow channel (52) in the circumferential direction about the flow path (S) by not more than 280 °.

Description

• - ein Sensorgehäuse, welches einen das Sensorgehäuse durchsetzenden Strömungskanal definiert, der längs einer eine axiale Richtung definierenden virtuellen, den Strömungskanal zentral durchlaufenden Strömungsbahn von Fluid durchströmbar ist,
• - eine gestaltveränderliche Strömungswiderstandsanordnung zur Bereitstellung eines Strömungswiderstands im Strömungskanal und
• - axial beiderseits der Strömungswiderstandsanordnung angeordnete Druckerfassungsformationen, welche der Erfassung von einen Fluiddruck im Strömungskanal repräsentierenden Druckwerten dienen.

The present invention relates to a differential pressure flow sensor comprising:

• a sensor housing which defines a flow channel passing through the sensor housing, which can be traversed by fluid along a flow path which centrally defines a fluid flow path and defines a virtual direction;
• - A shape variable flow resistance arrangement for providing a flow resistance in the flow channel and
• - Axially arranged on both sides of the flow resistance arrangement Druckfassungsformationen, which serve the detection of a fluid pressure in the flow channel representing pressure values.

• - einen außerhalb des Strömungskanals angeordneten Festlegeabschnitt, welcher zur Festlegung der Strömungswiderstandsanordnung am Sensorgehäuse ausgebildet ist, und
• - eine Mehrzahl von innerhalb des Strömungskanals angeordneten, relativ zueinander beweglichen Klappen, welche relativ zum Festlegeabschnitt beweglich sind zwischen einer von einem äußeren Krafteinfluss - abgesehen von der unvermeidlichen Schwerkraft - unbelasteten Ruhestellung und einer durch äußere Krafteinwirkung aufgrund von Fluidanströmung längs der Strömungsbahn ausgelenkten Auslenkstellung.

In this case, the flow resistance arrangement has:

• - A arranged outside the flow channel fixing portion, which is designed to determine the flow resistance arrangement on the sensor housing, and
• - A plurality of arranged within the flow channel, relatively movable flaps, which are movable relative to the fixing portion between a by an external force influence - apart from the unavoidable gravity - unloaded rest position and a deflected by external force due to Fluidanströmung along the flow path deflected position.

Such differential pressure flow rate sensors, which allow detection of an amount of fluid flowing through the flow passage per unit time based on a pressure difference between upstream fluid pressure and downstream fluid pressure, are inter alia proximal flow sensors (flow sensors) proximate to the patient. in ventilators for artificial respiration of living things known. This is also the preferred use in the present application, although not the only possible application, of the flow sensor described with the present application.

A generic flow sensor is from the WO 91/06830 A1 known. This document describes a flow sensor, which on the one hand as insensitive to be unavoidable during a ventilation operation on the sensor housing accumulating liquid and which on the other hand, both at low and at high flow velocities a linear relationship between the occurring across the flow resistance arrangement away pressure drop and the flow rate of the Flow sensor to have flowing through fluid.

In the artificial respiration of human or animal patients, on the one hand, the respiratory gas supplied to the patient is conditioned, ie tempered and provided with a predetermined degree of humidity, in order to make the respiratory gas more compatible with the patient. On the other hand, the patient also gives moisture to the expiratory breathing gas in his lungs. This can result in moisture precipitation in the flow sensor.

In doing so, moisture does not only precipitate in small droplets of surfaces of the flow sensor wetted by the respiratory gas, but as the flow sensor continues to operate, a liquid film or even a liquid reservoir can form in the sensor housing. The precipitation of moisture on the duct wall radially outwardly delimiting the flow channel is further promoted by the fact that first of all the exhaled respiratory gas has a relative humidity close to saturation and secondly that the temperature of the exhaled respiratory gas is higher than the ambient temperature at which the flow sensor is usually located.

The flow resistance arrangement of the known flow sensor comprises three flaps, which in their rest position, in which they are not flown by respiratory gas, greatly reduce the flow-through cross-sectional area of the flow channel in the region of their arrangement. Upon flow of the flaps along the flow path these are deflected against a restoring force, which resets the flaps in case of cessation of the flow of respiratory gas in its rest position. Due to the deflection of the flaps caused by the flow, the flow-through cross-sectional area of the flow channel in the region of the arrangement of the flaps is increased.

Forms a liquid reservoir to such an extent that a deflectable flap immersed in the rest position in liquid, the force required for the deflection of the flap at its flow is increased and thereby falsified the measurement result of the flow sensor.

The from the WO 91/06830 A1 known flow sensor has, as a first measure to reduce the sensitivity to moisture precipitating in the flow channel in the region of the pressure detection formations on both sides of the flow resistance arrangement an inner tube on, which is arranged at a radial distance from the channel outer wall. This is to make it possible for the inner tube to be able to heat to the elevated ambient temperature of the exhaled respiratory gas. Thus, due to a lack of temperature difference with respect to the flowing gas, no or at least less liquid would condense on the inner tube, especially the exhaled respiratory gas.

Although the outer wall usually having ambient temperature then remains as a condensation or precipitation surface, but can not influence the deformation behavior of the flow resistance arrangement due to the spatial radial separation of the screened through the inner tube flow passage.

The annular gap between the inner tube and the inner tube surrounding the outer channel wall of the known flow sensor is used for the determination of the flow resistance arrangement on the sensor housing. The securing section of the flow resistance arrangement of the known flow sensor runs completely, d. H. closed to the flow path at the mounting location of the flow resistance arrangement. This fixing portion is immovably taken up and fixed along its entire circumference between two housing components immediately adjacent to one another along the flow path.

As a further measure to reduce the sensitivity to moisture precipitating in the flow channel, the flow resistance arrangement of the WO 91/06830 A1 known flow sensor on three flaps, which close in their unloaded by a flow along the flow path rest position largely an annular flow passage through the flow resistance arrangement and can be deflected from the rest position into the deflection position against the material and shape-related elastic restoring force. The flaps cantileously project as leaf springs from the fixing portion, wherein the successive in a direction orthogonal to the flow path flaps projecting in opposite directions from the fixing portion. This emphasizes the WO 91/06830 A1 in that the central flap, which in the rest position closes a central portion of the flow passage, protrudes towards the pressure detection formations at an end portion of the fixing portion remote from the pressure detection formations, while the peripheral flaps on both sides of the central flap project in opposite directions away from the pressure detection formations.

This is intended to ensure that, when liquid accumulates in the inner tube, the deflectable, so far away from the coupling point of the central flap on the fixing portion longitudinal end of the central flap is located far away from the accumulated in the inner tube liquid and thus away from the accumulated liquid can be influenced as little as possible. This is based on the current state of the art as well as for the present invention valid approach that the flow sensor is arranged in the ventilation mode with a substantially horizontal flow path such that the pressure detection formations on the channel outer wall as possible at a geodetically highest area. In that case, liquid flowing down the inner tube or generally on a channel wall flows gravitationally away from the pressure-detecting formations.

A disadvantage of this solution is on the one hand, the high production cost, which is required by the additional arrangement of the inner tube with a radial distance from the channel outer wall in the region of the arrangement of the flow resistance arrangement. A further disadvantage is that, in particular, the coupling points of the peripheral flaps extend on the fixing section over a relatively large angular range around the flow path and the Auskragrichtung the peripheral flaps - in contrast to the central flap - starting from their respective coupling point so asymmetrically inclined runs that the coupling point an almost equally large extension component in the cantilever direction as orthogonal to this. This results in an undesirable stiffening of the edge-side flaps with respect to a operationally desired bending of the flaps about an orthogonal to the cantilever bending axis. All flaps are integrally connected to the fixing section.

From the US 4006634 A is a differential pressure flow sensor without additional inner tube known, the flow resistance arrangement comprises a plurality of identically shaped flaps, which are arranged sequentially in the circumferential direction. They are integrally connected at their radially outer edge region with a ring-shaped closed encircling fixing section. The identically shaped flaps each have a sector shape, which tapers from radially outward to the sensor track. A central section of the US 4006634 A known flow resistance arrangement is formed as a permanent annular opening. The flaps are therefore not enough to the middle of the flow channel.

From the DE 10 2010 040 287 A1 a further pressure difference flow sensor without additional inner tube is known, the flow resistance arrangement comprises a single deflectable by bending flap and the flap completely in the circumferential direction surrounding the flow path defining portion. This fixing section protrudes into the flow channel and forms a partition wall in a peripheral region close to the channel outer wall, which prevents liquid accumulated in the sensor housing from flowing away in at least one direction.

From the EP 373886 A1 a differential pressure flow sensor is known, the flow channel in the region of the arrangement of the flow resistance arrangement only in the pressure detection formations diametrically opposite region has a part-circular cross-section, while the flow channel in the pressure detection formations having region has a rectangular cross-section. The single flap of the integrally formed flow resistance arrangement is connected via a hinge region as a coupling point with a fixed outside of the flow channel fixed to the sensor housing.

The EP 373886 A1 refers to the fact that the radial gap between the outside of the channel outer wall, the hinge region remote edge of the flap and the channel outer wall is crucial for the measurement accuracy of the sensor at low fluid flows. The smaller the radial gap, the more accurately the sensor can detect even small fluid flows. In the aforementioned DE 10 2010 040 287 A1 this radial gap is defined between the flap edge remote from the joint area and an edge of the fixing area. Since the flap of the EP 373886 A1 known flow resistance assembly is not surrounded by the fixed area, discloses the EP 373886 A1 to provide radially opposite the flap edge remote from the hinge region an axially short, circumferentially extending radial rib on the channel outer wall which extends to the flap edge remote from the hinge region in its rest position. This should in turn be achieved in terms of absolute low radial gap between the flap and Kanalaußenwandung. The EP 373886 A1 However, even on the conflict of objectives that arises in this way, there is a difference between the smallest possible detectability of low fluid flows on the one hand and the most unhindered outflow of fluid that is carried along by the fluid and accumulates in the vicinity of the flow resistance arrangement on the other hand. The first-mentioned goal requires the smallest possible radial gap and thus a radially highest possible radial rib, while the second-mentioned goal requires the largest possible radial gap and consequently a radially as flat as possible radial rib.

It is an object of the present invention to simplify the structure of the flow sensor of the type mentioned and at the same time to further improve its accuracy.

The present invention solves this problem with a flow sensor, as described in the introduction, in that the fixing section surrounds the flow channel in the circumferential direction around the flow path by not more than 280 °.

When the fixing portion does not surround the flow channel by more than 280 °, there is a circumferential portion free from the fixing portion of at least 80 ° angular extent, beyond which the fixing portion does not extend and thus also not facing a movable flap edge of at least one of the flaps. Thus, at least one flap of the plurality of flaps opposite the channel outer wall, without a part of the fixing portion protrudes radially into the flow channel or without the fixing portion in this peripheral region would establish a parting line radially opposite the flap edge. Preferably, the free from the fixing portion peripheral portion is a detection peripheral portion in which - although at an axial distance from the flow resistance arrangement - at least one pressure detection formations, preferably all Druckfassungsformationen, is or are formed diametrically opposite.

To avoid an undesirable liquid barrier, the channel outer wall in the region of the flow resistance arrangement does not have a radial rib projecting in the circumferential direction towards the flow path. This is dispensable because of the provision of a plurality of flaps.

The flap edge of each flap, which is remote from the detection circumferential section in the direction orthogonal to the flow path, is preferably movable along the flow path so that liquid collecting in the region of the flow resistance arrangement can pass the flow resistance arrangement at least when the flaps are deflected. The incomplete enclosure of the flaps by the securement section allows this.

Preferably, the fixing portion is formed symmetrically with respect to a coupling portion containing all the coupling points at which the plurality of flaps are connected to the fixing portion. The abovementioned circumferential portion which is free of the fixing portion is preferably diametrically opposite this coupling portion for the reasons stated above. Around To ensure a possible unhindered flap movement, extending from the fixing portion peripheral portion extends in the circumferential direction preferably over a larger angular range than the coupling portion.

In order to achieve similar flow conditions in the flow channel over the largest possible circumferential section around the flow path, the flow resistance arrangement is preferably designed mirror-symmetrically with respect to a mirror symmetry plane containing the flow path.

Since, for these reasons, the circumferential portion free of the fixing portion should be as large as possible, it is provided according to a preferred embodiment of the present invention, that the fixing section the flow channel in the circumferential direction around the flow path by not more than 180 °, preferably not more than 100 ° surrounds.

For a better understanding of the present application, some terms used in the present application are defined below:

The flow path may be a curved flow path. It is preferably a straight-line flow axis. It forms a center line of the volume enclosed by the channel outer wall. The flow path initially defines an axial direction and, based thereon, a radial direction orthogonal to the axial direction and a circumferential direction about the flow path. The flow path is thus the basis of an endogenous cylindrical coordinate system of the flow sensor or of the flow channel. In the less likely case of a curved flow path, the tangent to the curved flow path at a predetermined location defines an axial direction at that location.

The pressure sensing formations may be pressure sensors - on each side of the flow resistance arrangement of at least one - which sense the pressure in the portion of the flow channel in which they are located. Since the flow sensor is preferably a disposable or disposable sensor, preferably no measuring device is provided on the sensor housing itself. The pressure detection formations are therefore preferably detection channels - again on each side of the flow resistance arrangement of at least one, preferably exactly one - which respectively open into a portion of the flow channel. Through these detection channels of the prevailing at the location of their confluence in the flow channel fluid pressure can be transmitted along the detection channel and detected at the other end of the detection channel, far from the location of the junction, each by at least one pressure sensor.

The shape variability of the flow resistance arrangement serves to provide a passage opening with a variable flow cross section with the flow resistance arrangement. This passage opening is largely closed in the absence of fluid flow through the flaps and thus their durchströmbare cross-sectional area is minimal. As the flow of fluid increases in volume, the cross-sectional area which can flow through becomes larger as a result of increasing deflection of the flaps. The deflection position is therefore not a defined position, but depends on the amount of fluid flowing through the passage opening per unit of time.

Although the flow channel of the flow sensor of the present invention may have any cross-sectional shape and also change along the flow path. To achieve a laminar flow in the flow sensor which is as laminar as possible, at least the passage opening closable by the flaps in the flow resistance arrangement has a circular cross section and the flow channel has a circular flow cross section in the regions axially axially adjacent to the flow resistance arrangement. The circular shape of the flow cross-section may be locally disturbed by the pressure detection formations. However, this should be negligible according to the present application, since the detection peripheral portion associated with each pressure sensing formation preferably does not extend circumferentially about the flow path by more than 35 °.

Likewise, in the extension region of the coupling section, the shape of the passage opening of the flow resistance arrangement may be undefined since there is a permanent physical connection of the movable flaps to the fastening section in the coupling section. Nevertheless, the shape of the through hole outside the coupling portion is preferably circular or teilkreisringförm ig.

In order to be able to provide the greatest possible freedom of movement for all flaps movably arranged on the flow resistance arrangement, all attachment points of the flaps on the fixing section are preferably located in a contiguous angle sector around the flow path whose angular extent is not more than 60 °, preferably not more than 50 °, particularly preferably not more than 45 °. The smaller this angle sector, which is also referred to as the "coupling section" above, is the more advantageous the angular sector can be Relative mobility of the flaps to each other and the flaps are provided relative to the fixing portion. This applies to both the possible available degrees of freedom of movement of the individual flaps as well as the forces required for their movement or deflection from the rest position, which forces can be reduced as the coupling section becomes smaller.

An advantage obtainable with the present invention through the use of a plurality of flaps lies in the fact that each flap can be designed such that an edge section of a respective flap, which is opposite in the rest position of the channel outer wall, moves not only axially along the flow path but also along the flow path Also has a significant radial motion component in the direction of the flow path out. Although it should not be ruled out that the flap edge portion also moves in the circumferential direction during the transition between the rest position and the deflection position of the affected flap; however, in the transition from the rest position to the deflecting position, the axial and radial coordinates of the flap edge portion preferably change more, preferably the axial coordinate by a factor of 4 or more, and the radial coordinate by a factor of 2 or more, as the peripheral coordinate of the flap edge portion. This is preferably true for each of the plurality of flaps. This preferably also applies to the entire flap edge of each flap, wherein the circumferential center of the flap edge, as well as the flap edge portion, reference point for determining the coordinate change of the flap edge or the flap edge portion in the displacement of the flap from the rest position to the deflection position.

Such an advantageous degree of freedom of movement of the shape-changing flow resistance arrangement can be achieved in that at least one flap, preferably that all flaps, in its extension region in the flow channel is divided or in a Hauptanströmbereich with - considering the non-flow-through flow sensor with the flaps in the rest position as a reference state - larger inflow area and in a Nebenanströmbereich associated with the Hauptanströmbereich with smaller inflow area. The Hauptanströmbereich is connected to achieve a fullest possible mobility only indirectly via the Nebenanströmbereich with the fixing section. The area-larger Hauptanströmbereich experiences when flowing along the flow path due to its larger inflow area a greater deflecting force than the Nebenanströmbereich. Although this is also flown and thus experiences a deflecting force. However, the Nebenanströmbereich essentially serves the connection of Hauptanströmbereichs with the fixed area. Due to the smaller area of the Nebenanströmbereichs this can be designed so that the Hauptanströmbereich performs by deformation of the Nebenanströmbereichs upon application of force by flow along the flow path a deflection movement in a desired deflection direction.

In order to be able to provide a passage opening of the flow resistance arrangement that is closed as completely as possible by the flaps in the rest position, the subdivision of a flap into the main and secondary inflow regions is preferably realized by slitting. The slot preferably has a slot which extends from one of the channel outer wall opposite flap edge portion radially inward into the valve interior. The slot may be rectilinear or / and curved and / or be angled one or more times.

Preferably, the main inflow region and the secondary inflow region are integrally formed in one piece. Likewise, the Nebenanströmbereich and the fixed area are preferably integrally formed contiguous.

In order to obtain an advantageous ratio of the total areas of main and Nebenanströmbereichen to each other, the flow resistance arrangement preferably has two or three flaps. Regardless of whether two or three flaps are provided, always two flaps asymmetrical flaps. Although these are preferably mirror-symmetrical to each other, but taken separately is asymmetrical.

Between the fixing area and the Nebenanströmbereich a flap, preferably all flaps, a joint area may be provided. Also, the hinge region is preferably formed integrally with both the fixed area and with the adjoining him Nebenanströmbereich.

A particularly preferred kinematics of the Hauptanströmbereichs in the adjustment of the flap from the rest position to the deflection position is obtained by deformation of the Nebenanströmbereichs. It is particularly preferred if at least one flap, preferably when all the flaps, the flow resistance arrangement in the displacement of the rest position in the deflection position about two mutually orthogonal pivot axes is pivotable or are. This can be achieved structurally in that at least a portion of the Nebenanströmbereichs is formed as a longitudinally along a web direction extending web portion in which a web cross-section in a direction orthogonal to the web longitudinal direction Cutting plane has a width-to-depth ratio of between 2 and 10, preferably between 2.5 and 8, particularly preferably between 2.9 and 3.1. Again, a consideration in the rest position applies as the reference position. As a result of the abovementioned dimensional relationships, the main inflow region can be pivoted about a first pivot axis about a bending axis orthogonal to the local longitudinal direction of the web by flow of the web section and can be pivoted about a second, to the first orthogonal pivot axis by torsion of the web section about a torsion axis parallel to the local web longitudinal direction. Thereby, the above-described preferred flap kinematics is achieved, according to which the channel outer wall opposite flap edge of Hauptanströmbereichs and thus the flap, preferably each flap, in the displacement of the rest position in the deflection position its axial and its radial coordinate changes much more than its peripheral coordinate.

In order to prevent the web section, for a given flow, from being deformed much more by bending than by torsion, the web section along which the specified width-to-depth ratio applies is preferably longer than it is wide. To achieve a targeted deformation characteristic under the load of a flow, the web portion may be formed tapering along its longitudinal extent. The web section preferably tapers in the direction away from the fastening section, so that the web section as a bending and torsion section can be formed radially closer to the flow path than to the channel outer wall.

Additionally or alternatively, the web portion may be angled or / and curved about an axis orthogonal to its local web longitudinal direction.

For reasons of symmetry are for a usability of the flow sensor for flow measurement in both opposite flow directions of the fixing portion and the plurality of flaps in the rest position in a common plane. This plane is for the same reason bidirectional applicability preferably orthogonal to the flow path at the location of the arrangement of the flow resistance arrangement.

As already explained in detail above, the flow resistance arrangement is preferably a one-piece component for facilitated producibility with a well-defined repeatable deformability. The flow resistance arrangement may in principle be formed of a thin metal foil, in which case a non-rusting metal is preferred because of the load with moisture entrained by the flow. Lower costs with high manufacturing accuracy can be achieved by a flow resistance arrangement formed from a plastic film. PET has proved to be a particularly suitable plastic film material. Preferably, the plastic film has a thickness of between 20 microns and 100 microns, more preferably between 30 and 75 microns, most preferably between 40 and 60 microns. According to a particularly preferred embodiment, the plastic film and thus the flow resistance arrangement may have a thickness of 50 microns. The thickness of the flow resistance arrangement is preferably substantially constant over its entire area of extent.

The thickness of the plastic film forms the above-mentioned depth dimension of the flow resistance arrangement. For a plastic film described above, preferably having a thickness of 50 μm, the width of the above-mentioned web section is in a range between 0.15 mm and 0.3 mm. The length of the web section is then preferably more than 1 mm, more preferably even more than 2 mm, in order to achieve the above-described torsion of the web section about its web longitudinal direction.

To further prevent moisture precipitation on the wetted by flowing fluid channel outer wall, the channel outer wall may be formed at least over an axial portion of the flow channel on an inner tube which is radially outwardly, with the interposition of a clearance gap, surrounded by an outer tube. The inner tube is thus shielded from the outside environment and can heat up faster to the temperature of the fluid flowing in the flow channel.

The sensor housing preferably produced by injection molding can be made of any desired thermoplastic material, but preferably of a MAPS blend particularly suitable for medical applications, comprising methyl methacrylate, acrylonitrile, butadiene and styrene, or polysulfone.

For particularly simple determination of the flow resistance arrangement on the sensor housing, the sensor housing may be formed at least in two parts, wherein a housing member has a recess into which the fixing portion is axially inserted, and wherein a further housing member has a stamp formation, which in the assembled state of the flow sensor to the fixing portion axially abuts and thereby axially fixed. An enclosure of the recess is preferably formed at least partially complementary to the peripheral shape of the Festlegeabschnitts, so that the flow resistance arrangement by mere arrangement of the Fixing portion is positioned correctly in the recess for their further operation.

With at least two-part design of the sensor housing, an undesired joint in the region of the rest position of a flap edge of one of the flaps can be advantageously avoided with a corresponding configuration of the joining regions of two axially immediately adjacent housing components. For such joints between two housing components promote the accumulation of liquid by capillary action. Therefore, it is preferred if a fixing-joining section of greatest axial approximation of the two housing components in the region of the fixing portion axially spaced from a channel-joining portion greatest axial approximation of the two housing components in the region of at least one deflectable flap edge. Thus, the channel-joining portion, which is the diametrically opposite the fixing-joint section, with axial distance from the flap edges of the flaps - when viewing the rest position as the reference position - be arranged during the fixing-Fügeabschnitt directly on the fixing portion and thus axially directly to the flow resistance arrangement can be located. Since the fixing-joining portion is located in the direction of gravity in the direction of normal orientation of the flow sensor over the channel-joining portion, and is preferably located at a highest portion of the flow channel, the fixing section for the accumulation of liquid in the vicinity of the flow resistance arrangement is unproblematic.

The flow sensor described herein has due to the described flap mobility the advantageous property that it starting from the desired orientation described in the paragraph above with horizontally oriented flow path and with the fixing section or / and Druckfassungsformationen geodetically highest portion of the flow channel by about 90 ° can be used rotated in both opposite directions of rotation around the flow path, without sacrificing accuracy. This is due to the above-described, about two mutually orthogonal pivot axes pivotable flaps.

Numerous flow sensors of the prior art react very sensitively with regard to their accuracy of measurement to their rotation about the flow path from their aforementioned desired orientation. Especially in the care of artificially ventilated patients, however, it inevitably always comes back to a deviation of the actual orientation of the flow sensor from its desired orientation. Even if the actual orientation of the flow sensor differs significantly from the desired orientation, the flow sensor presented here provides reliable measurement results and thus prevents triggering of alarms on ventilation devices. Nursing staff, which is currently moving an artificially ventilated patient and thus justifying a reorientation of the patient's flow sensor, can thus devote himself to his actual task, without being distracted or interrupted by unnecessary alarms from a connected ventilator.

The present differential pressure flow sensor is preferably designed for use in artificial respiration ventilators of living beings. Therefore, the sensor housing preferably has at its two longitudinal ends connecting formations for connection to ventilation gas-carrying flow lines, such as hose and / or piping. The flow sensor is preferably used to determine the inspiratory and / or inspiratory flow rate supplied to a patient per unit of time or per breath, and / or the amount of expired breathing gas withdrawn by it per unit of time or per breath.

• - einer Beatmungsgasquelle,
• - einer zwischen der Beatmungsgasquelle und einem patientenseitigen, proximalen Ende verlaufenden Beatmungsleitungsanordnung,
• - einer Ventilanordnung, umfassend ein Inspirationsventil und ein Exspirationsventil,
• - einer Durchflusssensoranordnung zur quantitativen Erfassung eines Gasflusses in der Beatmungsleitungsanordnung, umfassend wenigstens einen Durchflusssensor,
• - eine Drucksensoranordnung zur quantitativen Erfassung eines Gasdrucks von in der Beatmungsleitungsanordnung strömendem Gas,
• - einer Druckveränderungsanordnung zur Veränderung des Gasdrucks des in der Beatmungsleitungsanordnung strömenden Gases, und mit
• - einer Steuereinrichtung, welche dazu ausgebildet ist, den Betrieb der Druckveränderungsanordnung auf Grundlage von Messsignalen der Durchflusssensoranordnung zu steuern,

wobei wenigstens ein Durchflusssensor ein vorstehend beschriebener Differenzdruck-Durchflusssensor ist.The present invention therefore also relates to a ventilation device for the artificial respiration of a patient with

• a respiratory gas source,
• a ventilation duct arrangement extending between the respiratory gas source and a patient-side, proximal end,
• a valve assembly comprising an inspiratory valve and an expiratory valve,
• a flow sensor arrangement for the quantitative detection of a gas flow in the ventilation line arrangement, comprising at least one flow sensor,
• a pressure sensor arrangement for the quantitative detection of a gas pressure of gas flowing in the ventilation line arrangement,
• - A pressure change arrangement for changing the gas pressure of the flowing gas in the ventilation line assembly, and with
• a control device which is designed to control the operation of the pressure variation arrangement on the basis of measurement signals of the flow sensor arrangement,

wherein at least one flow sensor is a differential pressure flow sensor described above.

Typically, such ventilators have more than one flow sensor, namely a distal, patient-remote flow sensor and a proximal, patient-closer sensor. At least the proximal flow sensor is formed as described above.

If the sensor housing has an inner tube defining the flow channel and an outer tube radially shielding the inner tube, they are preferably formed on the side of the sensor housing facing the patient in the ventilation mode since the expiratory breathing gas usually has a higher temperature than the inspiratory one. The inner tube preferably begins at the longitudinal end of the sensor housing facing the patient in the ventilation mode, so that expiratory breathing gas flows through the flow channel when it enters the sensor housing through the outer tube, shielded from the outside environment.

• 1 eine Beatmungsvorrichtung mit einem Durchflusssensor der vorliegenden Erfindung,
• 2 eine perspektivische Ansicht eines Durchflusssensors der vorliegenden Erfindung,
• 3 eine Längsschnittansicht durch den Durchflusssensor von 2 längs einer Schnittebene, die die Strömungsbahn und Mittelachsen von Druckerfassungskanälen des Durchflusssensors enthält,
• 4 eine perspektivische Längsschnittansicht durch den Durchflusssensor von 2, geschnitten längs der Schnittebene von 3,
• 5 eine perspektivische Längsschnittansicht durch das Gehäusebauteil des Sensorgehäuses von 2, das den zweiten Axialabschnitt aufweist, geschnitten längs der Schnittebene von 3, und
• 6 Draufsichten auf eine beispielhafte Strömungswiderstandsanordnung mit zwei Klappen (Teilfigur A) und mit drei Klappen (Teilfigur B).

The present invention will be explained in more detail with reference to the accompanying drawings. It shows:

• 1 a ventilator with a flow sensor of the present invention,
• 2 a perspective view of a flow sensor of the present invention,
• 3 a longitudinal sectional view through the flow sensor of 2 along a sectional plane containing the flow path and center axes of pressure sensing channels of the flow sensor,
• 4 a perspective longitudinal sectional view through the flow sensor of 2 , cut along the cutting plane of 3 .
• 5 a perspective longitudinal sectional view through the housing member of the sensor housing of 2 having the second axial section, cut along the cutting plane of 3 , and
• 6 Top views of an exemplary flow resistance arrangement with two flaps (part A) and three flaps (part B).

In 1 an embodiment of a ventilation device according to the invention is generally designated 10. The ventilation device 10 used in the illustrated example for the artificial respiration of a human patient 12 , For the sake of completeness, it should be pointed out that the respiration device according to the invention 10 as a mobile ventilation device 10 on a rollable frame 13 can be included.

The ventilation device 10 has a housing 14 on, in the - not visible from the outside because of the opaque housing material - a pressure change arrangement 16 and a controller 18 are included.

The pressure change arrangement 16 is constructed in a conventional manner and has a respiratory gas source 15 in the form of a pump, a compressor or a blower, each of which is load-variable controllable and therefore not only the introduction of respiratory gas in the respiratory device, but also the change in the pressure of the introduced ventilation gas used. The respiratory gas source 15 (Gas source 15 ) may alternatively be formed by a pressure vessel, which to the housing 14 the ventilation device 10 is connectable. The pressure change arrangement 16 can the gas source 15 and optionally in addition - or in the case of a pressurized gas supply as a gas source alternatively - a reducing valve and the like. Next, the respiratory device 10 in a conventional manner, an inspiratory valve 20 and an expiratory valve 22 on.

The control device 18 is usually realized as a computer or microprocessor. It includes an in 1 Not shown storage device for the operation of the ventilation device 10 store necessary data and call it up if necessary. The storage device can also operate outside the housing during network operation 14 located and by a data transmission connection with the controller 18 be connected. The data transmission connection may be formed by a cable or a radio link. However, in order to prevent disruptions of the data transmission connection from affecting the operation of the respiratory device 10 the storage device is preferably in the control device 18 integrated or at least in the same housing 14 as this was added.

To enter data into the ventilator 10 or more precisely in the control device 18 has the respiratory device 10 a data input 24 on which in the in 1 represented example is represented by a keyboard. The control device 18 As an alternative or in addition to the illustrated keyboard, data can be obtained via various data inputs, for example via a network line, a radio link and / or via input connections 26 ,

To output data to the treating therapist, the respiratory device 10 an output device 28 have, in the example shown a screen.

For artificial respiration is the patient 12 with the pressure variation arrangement 16 above a ventilation line arrangement 30 connected. The patient 12 is intubated for this.

The ventilation line arrangement 30 points outside the case 14 an inspiratory tube 32 on. The inspiratory tube 32 may be interrupted and a first Inspirationsteilschlauch 34 and a second inspiration part tube 36 between which a conditioning device 38 for targeted moistening and possibly also temperature control of the patient 12 supplied fresh respiratory gas can be provided. The conditioning device 38 can with an external fluid supply 40 be connected via the water for humidification or a drug, such as anti-inflammatory or for the expansion of the respiratory tract, the respiratory gas can be supplied.

The ventilation line arrangement 30 has the expiratory valve 22 and further an expiratory tube 42 on which metabolised respiratory gas from the patient's lungs 12 is blown off into the atmosphere.

The inspiratory tube 32 is with the inspiratory valve 20 coupled, the expiratory tube 42 with the expiratory valve 22 , Of the two valves only one is open at the same time to the passage of a gas flow. The actuation control of the valves 20 and 22 is also done by the controller 18 ,

The control device 18 , is designed to provide ventilation operating parameters that control the ventilation of the ventilator 10 during the ventilation operation to repeatedly update or ascertain to ensure that the ventilation operation at any time as optimally as possible to the respective patient to be ventilated 12 is tuned. For this purpose, the ventilation device 10 Data transmission associated with one or more sensors that monitor the condition of the patient and / or the operation of the ventilator.

One of these sensors is a proximal flow sensor 44 which is in a Y-connector 45 those in the respiratory line 30 prevailing respiratory gas flow detected. The flow sensor 44 can by means of a sensor-line arrangement 46 with the input connections 26 the control device 18 be coupled. The sensor cable arrangement 46 may, but need not, include electrical signal transmission lines. You can also hose lines 43 have, in the flow direction on both sides of the flow sensor 44 prevailing gas pressure to the input terminals 26 transfer where these from pressure sensors 27 be quantified. The flow sensor 44 is a differential pressure flow sensor 44 ,

In the case 14 is another flow sensor 47 which is due to its greater distance from the patient 12 as a distal flow sensor 47 is designated.

Due to the location of its attachment in the Y-connector 45 is the proximal flow sensor 44 in contrast to the distal flow sensor 47 basically also able to control the flow of expiratory breathing gas through the expiratory tube 42 capture.

The correct function of the flow sensors 44 and 47 is for the correct operation of the ventilator 10 and thus for the health of the patient 12 essential.

It has been shown in operation that just the proximal flow sensor 44 because of its proximity to the patient 12 is subject to a greater risk of error than the distal flow sensor 47 , The proximal flow sensor 44 , through which also expiratory breathing gas flows, is for example stronger than the distal flow sensor 47 burdened by moisture contained in the respiratory gas. This is even more true when the distal flow sensor 47 as in the present example the 1 in the inspiratory direction upstream of the conditioning device 38 is arranged and thus essentially only flows through dry inspiratory breathing gas.

In 2 is an inventive embodiment of the differential pressure flow sensor 44 shown in perspective when viewed from the outside. The flow sensor 44 includes a sensor housing 46 , the two housing components 48 and 50 includes. The sensor housing 46 defines a flow channel 52 which the sensor housing 46 along a rectilinear flow path in the example shown S completely interspersed. The flow path S is therefore present a flow axis. However, this does not have to be the case. The flow path S may deviate from the illustrated embodiment also have a curved course.

The in 2 facing the viewer longitudinal end region 46a of the sensor housing is that to the patient 12 closer longitudinal end, the axially opposite to the flow path S longitudinal end 46b is that of the patient 12 further away longitudinal end of the sensor housing 46 ,

The two housing components 48 and 50 have at their facing longitudinal ends each a connecting flange 48a respectively. 50a on, which in each case over a pipe section 48b respectively. 50b of the associated housing component 48 respectively. 50 protrude radially outward. The flanges 48a and 50a touch each other to form a parting line 54 ,

Each housing component 48 respectively. 50 has a connection formation 48c respectively. 50c on which the coupling of the hose lines 43 for connection to the pressure sensors 27 serve. The connection formations 48c and 50c are formed in the illustrated example as a cylindrical connection piece, but may also have any other shape.

The connecting pieces 48c and 50c are interspersed in each case by a pressure sensing channel 56 respectively. 58 , which run parallel along straight channel axes K1 and K2 in the flow channel 52 extend. The pressure detection channels 56 and 58 thus enforce the sensor housing 46 and flow into the flow channel 52 , so one in the sensor channel 52 prevailing pressure via the pressure detection channels 56 and 58 as well as over the hose lines 43 to the pressure sensors 27 can be transferred and recorded there.

The 3 and 4 show in longitudinal section estuaries 56a and 58a the pressure detection channels 56 and 58 at the the flow channel 52 radially outwardly bounding channel outer wall 60 , The mouths 56a and 58a the pressure detection channels 56 and 58 form in the present example pressure sensing information of the flow sensor 44 which detects the detection of a fluid pressure in the interior of the flow channel 52 serve. The peripheral portion of the channel outer wall 60 over which the estuaries 56a and 58a extend forms a detection subsection.

In the housing component 48 is the pipe section 48b double-walled and includes an outer tube 62 and an intermediate arrangement of a clearance gap 64 radially inner tube arranged inside 66 ,

The the flow channel 52 radially outwardly bounding channel outer wall 60 is in the housing component 48 only on the inner tube 66 educated. The flow channel 52 in the housing component 48 is cylindrical.

The annular gap 64 , which is the inner tube 66 radially from the outer tube 62 separates, tapers to the flange 48a towards, because the wall thickness of the inner tube 66 in the axial direction to the flange 48a increases. The thickness of the outer tube 62 is, however, along the flow path S constant. As in the 3 and 4 is shown defined on the other housing component 50 only one pipe 68 the pipe section 50b so that the channel outer wall 60 on the radially inward-facing side of the tube 68 is trained.

The channel outer wall 60 in from the flange 50a protruding pipe 68 encloses a larger cross-sectional area than the channel wall 60 in the inner tube 66 , To compensate for this difference in size of enclosed area is in the second housing component 50 , preferably centrally in the of the duct wall 60 in the pipe 68 enclosed area, a document body 70 arranged, which as solid a volume of space in the pipe 68 occupied, so that the actually durchströmbare cross-sectional area in this area is smaller than that of the channel outer wall 60 enclosed area.

Before the design of the flow channel 52 in connection with the document body 70 is explained in more detail, let the flow resistance arrangement 72 pointed out which in 3 in its rest position, so unloaded by a fluid flow in the flow channel 52 as a flat structure with an extension plane orthogonal to the flow path S as well as orthogonal to the plane of the 3 runs. The further explained below flow resistance arrangement 72 has a fixing section 72a on, which in the parting line 54 between the housing components 48 and 50 is clamped, and has one in the flow channel 52 arranged, integral with the fixing section 72a contiguous flap section 72b on.

With flow through the flow channel 52 no matter in which direction, the flap section becomes 72b relative to the housing-fixed locking section 72a deflected, resulting in the flap section 72b covered or shaded cross-sectional area of the flow channel 52 decreases with increasing deflection, which in the area of the flow resistance arrangement 72 durchströmbare cross-sectional area of the flow channel 52 is enlarged.

The flow resistance arrangement 72 , more precisely: the flap section 72b , act in the flow channel 52 as a throttle, so that upstream and downstream of the flap portion 72b different fluid pressures in the flowing fluid 52 train over the estuaries 56a . 58a as the pressure detection information also in the pressure detection channels 56 and 58 and thus in the subsequent to this hose lines 53 are detectable. The pressure sensors 27 can thus have a pressure difference in the flow channel 52 upstream and downstream of the drag assembly 72 and according to a previously completed calibration of the flow sensor 44 starting from the pressure difference upstream and downstream of the flow resistance arrangement 72 the fluid flow through the flow sensor 44 along the flow path S determine. The operation of such a differential pressure flow sensor 44 is known per se.

The flow resistance arrangement 72 is located in the flow channel 52 in a first axial area 74 , which extends axially on both sides of the flow resistance arrangement 72 extends and along which one of the Kanalaußenwandung 60 enclosed cross-sectional area is approximately constant in magnitude and preferably also in terms of shape.

The aforementioned area in which the channel outer wall in the pipe 68 of the housing component 50 is formed and encloses a substantially constant larger cross-sectional area than in the first axial region, forms a second axial region 76 , Between the first axial area 74 and the second axial region 76 lies an external transience axial region 78 in which the channel outer wall 60 as it progresses along the flow path S from the smaller cross section of the first axial region 74 on the larger cross section of the second axial region 76 gradually, preferably linearly changes. In the illustrated embodiment, the pressure detection channel opens 58 of the housing component 50 in the external transience axial region 78 , Deviating from this, the first axial region 74 axially over the mouth 58a of the pressure detection channel 58 Be extended so that the two mouths 56a and 58a the pressure detection channels 56 and 58 essentially lead into an identical flow channel section.

The document body 70 is over a plurality of webs 80 in the area of its flow resistance arrangement 72 closer longitudinal end with the flange 50a or / and with the pipe 68 of the housing component 50 connected. The document body 70 is through the footbridges 80 stored on the fly, ie from the webs 80 away in the axial direction is the rest of the document body 70 without further connection with the surrounding pipe 68 so the flow channel 52 in the radial webs 80 free portion of the second axial region 76 the document body 70 Surrounds closed in the circumferential direction. The bridges 80 enforce the between the document body 70 and the channel outer wall 60 in the pipe 68 formed radial gap 82 , depending on their location, in the radial or / and in the axial direction.

The document body 70 has in its cantilevered portion on a rotationally symmetrical shape, in the example shown a cylindrical shape with a smooth, the flow channel 52 indicative outer surface.

At its the drag resistor assembly 72 nearer longitudinal end of the document body is fluid mechanical with the lowest possible flow resistance in the flow from the direction of the first axial region 74 formed, such as a spherical or Ellipsoidkalotte. The document body 70 therefore indicates that of the flow resistance arrangement 72 nearest longitudinal end an internal transience axial region 79 on, along which the body of the document 70 changed enclosed cross-sectional area. Beyond the internal transience axial region 79 is the second axial area 76 located, from the document body 70 enclosed cross-sectional area, which is thus no longer available for a flow with fluid, constant in the axial direction.

The bridges 80 , even if they are integrally injection-molded with the document body 70 are formed, remain in the consideration of the document body 70 enclosed volume volume outside. The bridges 80 are not part of the document body 70 but only its attachment formations.

The document body 70 also advantageously reduces the dead space in the interior of the flow sensor 44 , This reduces the body of the document 70 in the ventilator 10 for artificial respiration, of which the flow sensor 44 preferred component is the volume of gas that is not involved in pulmonary gas exchange. This is all the more advantageous, the lower the volume of gas exchanged per breath is pulmonary. For example, the artificial respiration of infants and toddlers requires only a small tidal volume.

As in 3 As can be seen, the outer-transience-axial region overlap 78 and the internal transience axial region 79 axially, to change the shape of the flow channel 52 To realize the shortest possible axial space, in return as long as possible axial distances with a constantly designed flow channel 52 in the flow sensor 44 to be able to train.

3 shows the flow sensor 44 in its ideal location during operation of the ventilator 10 , namely with horizontal flow path S and with parallel to the direction of gravity g running channel axes K1 and K2 so the mouths 56a and 58a the pressure detection channels 56 and 58 at a geodetically highest location of the flow channel 52 enter into this. From that the flow sensor 44 through-flowing fluid entrained moisture or liquid, which may be on the Kanalaußenwandung 60 precipitates then flows gravity driven from the mouths 56a and 58a away and do not disturb them.

A precipitate of liquid on the drag assembly 72 , ie at the flap section 72b , may take place, but the flow resistance arrangement is usually made of plastic having a thickness of less than 0.1 mm, preferably in a thickness range of 40 to 60 microns, so that the flow resistance arrangement 72 very quickly assumes the temperature of the fluid flowing around him, which prevents moisture precipitation. However, from the flow sensor 44 flowing fluid entrained droplets on the flap portion 72b land and wetting there.

Unlike numerous flow sensors 44 The prior art is the radially outer edge of the flap portion 72b in the rest position of the flow resistance arrangement 72 the channel outer wall 60 across from.

Thus, there is a fundamental risk that the Kanalaußenwandung 60 in the first axial area 74 opposite edge directly through to the Kanalaußenwandung 60 in the first axial area 74 Impacting liquid is impaired in its function.

The external transience axial region 78 creates here, with imputed ideal operational arrangement, as in 3 shown, a slope along which liquid from the first axial region 74 gravity driven into the second axial region 76 flows. In the second axial area 76 liquid may be the flow resistance arrangement 72 do not disturb anymore.

As a further measure to reduce the influence of possibly in the flow channel 52 accumulating liquid are in the first and in the second axial region 74 respectively. 76 as well as in the external transience axial region 78 a plurality of circumferentially successive, axially extending Abführnuten 84 educated. For the sake of clarity, only a few of the Abführnuten 84 provided with reference numerals.

The Abführnuten 84 extend in the housing component 50 from the parting line 54 in the axial direction along the Kanalaußenwandung 60 continuously at the flow resistance arrangement 72 past. The parting line 54 lies at least in that of the fixing section 72a or / and from the mouths 56a and 58a remote area of the channel outer wall 60 advantageously axially of the flow resistance arrangement 72 , in particular of the flap portion 72b , removed, so at least that of the fixing section 72a or / and from the mouths 56a and 58a remote radially outer edge portions of the flaps of the flow resistance arrangement 72 in the rest position of the parting line 54 are arranged away.

Dashed lines are in 3 an alternative course of the parting line with 54 ' designated. Assuming that the document body 70 holding bridges 80 completely in 2 right housing component 50 are formed, the parting line 54 ' also on the side of the flow resistance arrangement 72 run, on which the document body 70 is located. The first axial area 74 So it can be completely in the housing component 48 be educated. Helpful against unwanted accumulation of liquid in the area of the flow resistance arrangement 72 is if any of the fixing section 72a or / and from the mouths 56a and 58a remote edge portion of the flap portion 72b in the rest position no parting line 54 or 54 ' but only a portion of the channel outer wall 60 radially opposite.

Because of the axially continuous formation of Abführnuten 84 and the larger peripheral surface of the channel outer wall 60 in the second axial area 76 , compared to the first axial area 74 , can the Abführnuten 84 in the second axial area 76 have a larger circumferential dimension (width) than in the first axial region 74 or / and can the intermediate formations 86 between two circumferentially immediately adjacent Abführnuten 84 have a larger circumferential dimension (width).

These drainage grooves 84 allow the removal of moisture along that of the outer transience axial section 79 formed gradients with radial and axial distance from the radially outer edge of the flap portion 72b ,

Although, in the absence of accumulating liquid in the flow resistance arrangement 72 due to the flow resistance arrangement 72 axially passing axial grooves 84 a gap surface between the radially outer edge of the flap portion 72b and the radially opposite channel outer wall 60 increased, compared with an identical flow channel without Abführnuten 84 , However, here is two things to consider:

First, experience shows that in a vast majority of respiratory cases, there is moisture at the channel's outer wall 60 precipitates or / and in the area of the flow resistance arrangement 72 accumulates, so that of the Abführnuten 84 formed radial wells at least partially filled with liquid and thus are not completely permeable by breathing gas as the fluid. The effective radial gap radially outside the flap portion 72b , which of Ventilation gas is flowed through, is therefore smaller than the structural radial gap of the dry flow sensor in most applications 44 ,

Second, as liquid accumulates in the flow channel, the detrimental influence of the liquid on the function of the flap portion 72b significantly reduced or even completely eliminated. This advantageous effect of Abführnuten 84 overcompensates the in principle a measurement inaccuracy increasing effect of the radially into the wall mass around the flow channel 52 extending in radial grooves 84 enlarged radial gap around the flap section 72b ,

5 shows a perspective longitudinal sectional view of the housing component 50 without flow resistance arrangement 72 , In 5 is a preferred shape of the Abführnuten 84 and above all, the intermediate formations formed between them in the circumferential direction 86 shown.

These intermediate formations 86 have a ridge line in the center of their circumference 86a or a ridge area 86a on which or which of the sections of an intermediate formation 86 that is the flow channel 52 centrally traversing flow path S is nearest. Below is the intermediate formation 86 on the basis of a linear ridge line 86a instead of an equally possible area ridge area described. Starting from the ridge line 86a rises on both sides of the ridge line 86a in the circumferential direction of the radial distance of the channel outer wall 60 from the flow path S on. In the example shown close in the circumferential direction on both sides of the ridge line 86a flat surfaces 86b which run parallel to the flow path S and touch along the ridge line, the ridge line 86a defines an articulation axis about which the two planar surfaces are angled away from each other from the flow path S. The Abführnuten 84 between two intermediate formations 86 have a rectangular cross-section open to the flow axis S, ie the Abführnuten 84 are by three plane boundary surfaces, of which in each case two adjoining interfaces form a right angle with each other. Alternatively, the Abführnuten 84 also in the radial direction of the flow axis S Rejuvenate away, ie the Abführnuten 84 circumferentially bounding surfaces may be in the direction of the flow axis S be inclined towards each other.

The ridge line 86a acts as an effective overflow barrier that prevents liquid from a drainage groove 84 in the circumferential direction in an adjacent Abführnut 84 overflows.

In principle, the grooves extend in the first and in the second axial region 74 respectively. 76 with a groove bottom parallel to the flow path 84a , The groove bottom 84a one or more Abführnuten 84 may have a further slope slope in a longitudinal section, similar to the outer transience axial region 78 and thus the groove reasons in this area 78 provide a slope so that in the Abführnuten 84 Gravitationally accumulated liquid on this gradient further from the flow resistance arrangement 72 can be routed away or even from the sensor housing 46 can be discharged. Therefore, the longitudinal section in which the groove bottom 84a on progression to a longitudinal end of the sensor housing 46 away from the flow path S, preferably an end region, which the patientenfernere longitudinal end 46b of the sensor housing 46 contains. For example, this end region extends over not more than half, preferably not more than 25%, of the second axial region 76 ,

It can all axial grooves 84 in the second axial area 76 These have more gradients or it may only be part of the Abführnuten 84 have the incline. Since the further downslope for a liquid discharge therein relies on their correct orientation relative to the gravity direction of action, the part of the discharge grooves should be in a peripheral portion of the flow channel with the further downslope 54 be provided, which contains the geodesically deepest region thereof. This area is located in the 3 and 4 the mouths 56a and 58a the pressure detection channels diametrically opposite.

In 5 is also a rectangular recess 88 on the housing component 48 facing longitudinal end of the housing component 50 to recognize. This rectangular recess 88 serves to receive the substantially complementary designed fixing section 72a the flow resistance arrangement 72 ,

The fixing section 72a is bounded so that it is at the edge of the recess 88 essentially rests without play, so that the position of the flow resistance arrangement 72 and especially the flap section 72b in the flow channel 52 is clearly defined.

The flow channel 52 in the housing component 48 is present with smooth Kanalaußenwandung 60 educated. However, the Abführnuten can also in this area of the flow channel 52 be continued and continuously already from a place in the housing component 48 proceeding continuously axially on the flow resistance arrangement 72 over into the second axial area 76 , preferably to the longitudinal end 46b of the sensor housing.

In the 6A and 6B are advantageous embodiments of advantageous flow resistance arrangements 72 a flow sensor according to the invention 44 shown.

In 6A is with 72 ' a modified embodiment of the in 4 illustrated flow resistance arrangement 72 shown. Same and functionally identical components and component sections as in the 1 to 4 bear the same reference numerals, but apostrophes. The flow resistance arrangement 72 ' from 6A has a rectangular fixing section 72a ' on which complementary to the recess 88 in the housing component 50 is trained. The flap section 72b ' has two flaps 90a ' and 90b ' on.

Both the fixing section 72a ' as well as the flap section 72b ' are mirror-symmetrical with respect to a mirror symmetry plane SE, which in the example shown exactly between the two flaps 90a ' and 90b ' passes through. In the finished state contains the mirror symmetry plane SE the flow path S and the channel axes K1 and K2 ,

Due to the mirror symmetry between the two flaps 90a ' and 90b ' it is enough only in the 6A left flap 90a ' to describe.

The flap 90a ' , the part-circular flap edge 90a1 ' in the flow sensor 44 the with Abführnuten 84 provided duct outer wall 60 immediately radially opposite, defines a main inflow section 90a2 ' , which via a web-shaped Nebenanströmabschnitt 90a3 ' with the fixing section 72a ' is integrally connected.

Starting from the in 6A shown rest position of the flap section 72b ' at the onset of fluid flow in the flow channel 52 orthogonal to the plane of the 6A incident flow. Due to its significantly larger area acts on the main inflow area 90a2 ' a larger fluidic force than on the Nebenanströmbereich 90a3 ' ,

Because of its design as a web-shaped Nebenanströmbereich 90a3 ' this is driven by the action of a fluid mechanical load through the Hauptanströmbereich 90a2 ' deform more along the flow axis S than the Hauptanströmbereich 90a2 ' , The latter is due to the deformation of the Nebenanströmbereichs 90a3 ' shift more than deform.

The tributary area 90a3 ' , which at one to the flow path S orthogonal bend axis KA is kinked, is about two torsion axes Ta1 ' and ta2 ' twistable, which with the bar longitudinal directions SLA1 ' and SLA2 ' the two legs on both sides of the bending axis KA of the by-pass section 90a3 ' coincide.

Likewise, each of the two legs on both sides of the bending axis KA the Nebenanströmbereichs 90a3 ' one in the drawing plane of the 6A lying and the respective torsion axis Ta1 ' respectively. ta2 ' orthogonal bending axis bendable. For the sake of clarity, the two bending axes are not shown.

The total deformation of the Nebenanströmabschnitts 90a3 ' includes a torsion about a Summentorsionsachse Ta ' and a bend about one to the sum torsion axis Ta ' approximately orthogonal sum bending axis Ba ' , The two summation axes T ' and B ' are for the sake of clarity for the mirror-symmetrical flap 90b ' as sum deformation axes Tb ' and bb ' entered. The two summation axes bb ' and Tb ' thus form two linearly independent pivot axes about which the Hauptanströmbereich 90a2 ' relative to the fixing section 72a ' is mobile.

The coupling points A1 ' and A2 ' at which the flaps by means of the Nebenanströmbereiche 90a3 ' and 90b3 ' with the fixing section 72a ' are connected, lie with respect to the flow path S in a contiguous angle sector 92 ' , which extends in the example shown no more than 20 °. This causes the two flaps 90a ' and 90b ' , in particular their Hauptanströmbereiche 90a2 ' and 90b2 ' relative to the fixing section 72a ' already movable by low flow, the mobility around the two summation axes T ' and B ' a magnitude large change in the flow resistance arrangement 72 ' allows existing through-flow cross-sectional area.

In 6B is an alternative embodiment of a flow resistance arrangement 72 " shown, the flap section 72b " three flaps 90a " . 90b " and 90c " having.

Again, the two side flaps 90a " and 90b " with respect to the mirror symmetry plane SE mirror-symmetrical, while the third, between these edge-side flaps 90a " and 90b " located central flap 90c " is mirror-symmetric in itself to the plane SE. Consequently, the marginal flaps 90a " and 90b " constructed asymmetrically in itself. Again, the description is the flap 90a " because of the symmetry condition on the flap 90b " applicable. The tributary area 90a3 " first of all, it tapers off from the coupling point A1 " and then goes into a bridge section constant width dimensions. The tributary section 90a3 " is about a torsion axis Ta " twistable and is around a bending axis B " bendable. The bending axis B " is for all by-pass sections 90a3 " . 90b3 " and 90c3 " roughly a common collinear bending axis B " , The torsion axes of the individual web sections are parallel to one another and to the bending axis B " orthogonal. Of the torsion axes are only the axes Ta " and tc " in 6B displayed. The missing axis tb " results from the axis Ta " by said mirror symmetry condition.

The central flap 90c " is basically twistable, but is not due to their symmetrical flow usually around the torsion axis T2 " be deformed. The fan-shaped central flap 90c " is therefore predominantly by bending around the bending axis B " deform. The marginal flaps 90a " and 90b " On the other hand, they are not only theoretical about two mutually orthogonal pivot axes Ta " respectively. tb " and B " pivotally, but will actually perform this pivotal movement due to their asymmetrical arrangement with respect to the flow path S in the ventilation mode. This can already at low deformation of the flap portion 72b ' a relatively large change in the flow-through cross-sectional area at the flow resistance arrangement 72 " be effected.

Thus, not only over a wide range of flow rates per unit time accurate flow sensor is achieved, but possibly in the area of the flap edges 90a1 " . 90b1 " and 90c1 " accumulating fluid can due to the high mobility of the valves 90a " . 90b " and 90c " the flow resistance arrangement 72 " Pass even axially with only a small flow, even if no Abführnuten 84 are provided in the flow channel.

The angle sector 92 " in the embodiment of the 6B is bigger than the sector 92 ' in 6A but does not exceed 45 °.

Only for the sake of completeness, it should be noted that in the 6A and 6B identical and functionally identical components or component sections are denoted by the same reference numerals, but with different numbers of apostrophes.

The partial separation of the Hauptanströmabschnitte from the Nebenanströmabschnitten one and the same flap, as well as a separation of the flaps with each other, is effected by slitting the material of the flow resistance arrangement. Preferably, the slot width is smaller than the width of web-formed sections of the Nebenanströmbereiche.

By different design of the tapered portions of the Nebenanströmbereiche 90a3 " and 90b3 " can the position of the respective bending axes B " these Nebenanströmbereiche be approximated or removed from the flow path S.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 9106830 A1 [0004, 0009, 0012]
• US Pat. No. 400,664 A [0015]
• DE 102010040287 A1 [0016, 0018]
• EP 373886 A1 [0017, 0018]

Claims (12)

Differential pressure flow sensor (44) - with a sensor housing (46) which defines a sensor housing (46) flow channel (52) along an axial direction defining virtual, the flow channel (52) centrally traversing flow path (S) of fluid flow-restricting arrangement (72, 72 ', 72 ") for providing a flow resistance in the flow channel (52) and pressure sensing formations (56a, 58a) arranged axially on either side of the flow resistance arrangement (72, 72', 72"), which serve to detect pressure values representative of a fluid pressure in the flow channel (52), the flow resistance arrangement (72; 72 '; 72 ") comprising: - a retaining portion (72a; 72a';72a") disposed outside the flow channel (52) for defining the flow resistance arrangement (72, 72 ', 72 ") on the sensor housing (46) is formed, and - a plurality of within the flow channel (52) arranged, relatively movable flaps (90a ', 90b'; 90a ", 90b", 90c ") which are movable relative to the fixing portion (72a, 72a ', 72a") between a position of unloaded force exerted by an external force influence, except for the unavoidable gravity, and an external force due to fluid flow along the length Flow path (S) deflected deflection position, characterized in that the fixing portion (72a, 72a ', 72a ") surrounding the flow channel (52) in the circumferential direction around the flow path (S) by not more than 280 °. Differential pressure flow sensor (44) after Claim 1 , characterized in that the fixing portion (72a, 72a ', 72a ") surrounds the flow channel (52) circumferentially about the flow path (S) by not more than 180 °, preferably not more than 100 °. Differential pressure flow sensor (44) after Claim 1 or 2 , Characterized in that all the coupling points (A1 ', A2'; A1 ", A2", A3 ") ( '; 72a in a continuous angular sector (92 72a 72a) of the flaps on the setting section"', 92 ") to the flow path (S) whose angular extent is not more than 60 °, preferably not more than 50 °, more preferably not more than 45 °. Differential pressure flow sensor (44) according to any one of the preceding claims, characterized in that at least one flap (90a ', 90b'; 90a ", 90b", 90c ") in its extension region in the flow channel (52), preferably by slitting, is divided into a main inflow region (90a2 ', 90b2', 90a2 ", 90b2", 90c2 ") with - when viewing the non-perfused flow sensor (44) with the flaps (90a ', 90b';90a", 90b ", 90c") in the rest position as a reference state - larger inflow area and in a Nebenanströmbereich (90a3 ', 90b3', 90a3 ", 90b3", 90c3 ") connected to the Hauptanströmbereich (90a2 ', 90b2', 90a2", 90b2 ", 90c2") smaller inflow area, wherein the Hauptanströmbereich (90a2 ', 290b2', 90a2 ", 90b2", 90c ") only indirectly over the Nebenanströmbereich (90a3 ', 90b3', 90a3", 90b3 ", 90c3") with the fixing portion (72a, 72a '70a ") is connected. Differential pressure flow sensor (44) after Claim 4 , characterized in that at least a portion of the Nebenanströmbereichs (90a3 ', 90b3', 90a3 ", 90b3", 90c3 ") as along a longitudinal direction web (SLa1 ', SLa2', SLa", SLc ") extending web portion is formed, in in which a web cross-section in a sectional plane orthogonal to the longitudinal direction of the web (SLa1 ', SLa2', SLa ", SLc") has a width-to-depth ratio of between 2 and 10, preferably between 2.5 and 8, particularly preferably between 2 , 9 and 3.1. Differential pressure flow sensor (44) after Claim 5 , characterized in that the web portion, along which the specified width-to-depth ratio applies, is longer than it is wide. Differential pressure flow sensor (44) according to one of Claims 5 or 6 , characterized in that the web portion tapers along its longitudinal extension, preferably in the direction away from the fixing portion (72a; 72a '; 70a "), and / or is angled or curved about an axis orthogonal to the longitudinal extent. The differential pressure flow sensor (44) according to any one of the preceding claims, characterized in that the fixing portion (72a; 72a '; 70a ") and the plurality of flaps (90a', 90b ';90a", 90b ", 90c") in the Rest position lie in a common plane. Differential pressure flow sensor (44) according to any one of the preceding claims, characterized in that the flow resistance arrangement (72; 72 '; 72 ") is a one-piece component. Differential pressure flow sensor (44) according to any one of the preceding claims, characterized in that the sensor housing (46) is formed at least in two parts, wherein a housing member has a recess into which and wherein a further housing member has a stamp formation, which in the fully assembled state of the flow sensor (44) on the fixing portion (72a, 72a ', 70a ") axially abuts and this thereby axially fixed. Differential pressure flow sensor (44) according to any one of the preceding claims, characterized in that the sensor housing (46) is formed at least in two parts, wherein two axially immediately adjacent housing components between them hold the fixing portion (72a, 72a ', 70a "), wherein a Festlege -Fitting portion greatest axial approximation of the two housing components in the region of the fixing portion (72a, 72a ', 70a ") is located axially spaced from a channel-joint portion of the greatest axial approximation of the two housing components in the region of a deflectable flap edge. A respiratory device (10) for artificial respiration of a patient with - a respiratory gas source (15), - a ventilation duct arrangement (30) extending between the respiratory gas source (15) and a patient-side proximal end, - a valve arrangement (20, 22) comprising an inspiratory valve ( 20) and an expiratory valve (22), - a flow sensor arrangement (44, 48) for the quantitative detection of a gas flow in the ventilation line arrangement (30), comprising at least one flow sensor (44), - a pressure sensor arrangement (27) for the quantitative detection of a gas pressure of gas flowing in the ventilation duct arrangement (30), a pressure change arrangement (16) for changing the gas pressure of the gas flowing in the ventilation duct arrangement (30), and having - a control device (18) which is designed to control the operation of the pressure change arrangement on the basis of measuring signals the flow sensor assembly (44, 48) to control, thereby ge indicates that at least one flow sensor (44) is a differential pressure flow sensor according to one of the preceding claims.

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