DE102021124785A1 - flow sensor - Google Patents

Abstract

According to the invention, a flow sensor (1) is provided according to the differential pressure principle, having a housing (2) which has a first housing section (3), a second housing section (5) and a flow channel (7) along a flow path (8) for a fluid the first and second housing sections (3, 5), with a flow resistance arrangement (9) in the flow channel (7) fixed to at least one of the first housing section (3) and the second housing section (5), and with a first pressure sensing connection (11) and a second pressure sensing connection (13), and having a condensate drain assembly (20) having at least one drain channel (18) out of the housing (2) and at least one flow section (25) adapted to provide a Flow of condensate outside, preferably at least partially flow channel peripheral, to allow the flow channel (7) to the drain channel.

Description

The present invention relates to a flow sensor, in particular a differential pressure flow sensor, a system with such a flow sensor and a medical ventilator with such a system.

Differential pressure flow sensors determine the amount of fluid flowing through a flow channel per unit of time on the basis of a pressure difference between the fluid pressure that prevails upstream of a flow resistance arrangement and the fluid pressure that exists downstream. Flow sensors of this type are used in particular in respirators or devices for the artificial respiration of living beings. However, other uses for the flow sensor described here are also possible.

The basic principle of a generic flow sensor is, for example, in DE 20 30 775 or the WO 91/06830 A1 described.

During artificial respiration, the breathing gas supplied to the patient is varied in temperature upon inspiration and humidified to a predetermined level to make it more comfortable for the patient. Since the humidified ventilation gas is at a higher temperature than the environment and since the flow sensor is not heated, part of the moisture in the ventilation gas condenses on the inner surfaces of the flow sensor. This can cause moisture to accumulate in the sensor.

This results not only in small droplets of moisture on the surfaces wetted by the ventilation gas, but also possibly in a liquid film or reservoir in the flow channel of the flow sensor. It is particularly problematic when liquid accumulates in such a way that it impairs the movement of the elastic body or the elastic membrane of the flow sensor. As a result, the force required to deflect the body or the membrane when the flow occurs is increased and the differential pressure measurement can be negatively influenced or falsified as a result.

In the prior art, attempts are made in various ways to avoid this problem. In the WO 91/06830 A1 For this purpose, an inner tube is arranged on both sides of the flow resistance arrangement, which inner tube is arranged at a radial distance from the outer wall of the duct. This is intended to enable the inner tube to be able to heat up to the temperature of the exhaled ventilation gas, which is higher than the ambient temperature. Furthermore, in the WO 91/06830 A1 attempts to cantilever the flaps of the flow resistance arrangement in the manner of leaf springs and to arrange them geometrically in such a way that unfolding can be influenced as little as possible by an accumulating liquid. Disadvantages of these approaches are the high production costs and in particular the fact that the entire flow sensor can only be arranged in a specific position so that there is as little influence as possible from liquid precipitation. This means that the flow sensor cannot be flexibly positioned.

The US4932269A counteracts the problem by arranging a water trap at the bottom of the flow channel, which is arranged in the axial direction of the flow channel, ie in the direction of flow within the flow channel. A draining of accumulating liquid is not guaranteed here, and here too there is the above-mentioned disadvantage that a flexible spatial arrangement of the flow sensor is not possible.

The U.S. 2021/0162151 A1 follows a similar approach in which axial drainage channels are located within the flow channel on either side of the flow resistance assembly, with the drainage channels being substantially opposite the pressure sensing elements with respect to the flow axis. Very similar to US4932269A The difficulty here is that a free and flexible arrangement of the flow sensor in the room is not possible if optimal drainage of condensed liquid is to be guaranteed. Here, too, the accumulated liquid cannot drain away.

The DE 40 34 176 A1 discloses a spirometry measuring adapter for a ventilator, which has a cylindrical cavity separated from the flow channel for collecting condensate that forms, from which a condensate elimination nozzle leads to the discharge of the condensate to the outside. In this arrangement, the flow channel and the cylindrical cavity are separated from each other, and the entire measuring adapter is only intended to function when it is suspended vertically, ie when the flow channel is in a vertical position. Accordingly, the disadvantages mentioned above are not reduced by this solution.

In the DE 10 2018 204 799 A1 the applicant tries to solve the problem in a similar way. Here, too, axial discharge grooves are formed in the flow channel, but here they are distributed over the entire circumference of the flow channel and by a different Diameter on both sides of the flow channel creates an axial gradient, along which the liquid accumulating in the discharge grooves can drain. However, this geometric change cannot eliminate the disadvantage that, with a specific arrangement in the room, the outflow of the condensed liquid is not guaranteed. The accumulated liquid also largely remains in the flow channel.

It is therefore the object of the present invention to provide a flow sensor that at least partially overcomes the disadvantages mentioned above, improves or optimizes the outflow of condensate in and out of the flow channel, thereby ensuring a reliable measuring function in all spatial positions and offering a simple construction . A further object of the invention is to provide a system with a flow sensor that enables the flow through the flow sensor to be measured as reliably and error-free as possible. Yet another object of the invention is to provide a ventilator having an improved system for measuring flow and offering optimized handling.

These objects are solved by the subject matter of claims 1, 14 and 17. Further advantages and possible embodiments are the subject matter of the dependent claims.

One aspect of the present invention relates to a flow sensor based on the differential pressure principle, having a housing that includes a first housing section, a second housing section, and a flow channel along a flow path for a fluid through the first and second sections, a flow resistance arrangement in the flow channel, which comprises at least one of the first housing portion and the second housing portion, a first pressure sensing connection and a second pressure sensing connection, and a condensate drain assembly having at least one drain channel out of the housing and at least one flow section adapted to allow a flow of condensate outside, preferably at least partially flow channel circumferential to allow flow channel to the drain channel.

The special design of the condensate drain arrangement results in a reliable measuring function of the flow sensor because the condensate drain is optimized. As a result, the condensate no longer remains in the flow channel, either through passive draining of the liquid through the capillary effect, by gravity or through active suction or pumping out of the liquid when using a pump on the drain channel. The overall construction is kept simple and can be produced without great effort. In particular, the flow sensor enables flexible use, because the condensate drain works essentially independently of the geometric position of the sensor.

In a preferred embodiment, the condensate drain arrangement can have axial channels or grooves in the flow channel, with the at least one flow section adjoining at least one axial channel. In this context, axial means that the channels run along the flow channel. This improves the drainage of condensate from distant areas of the flow channel. Since the axial channels or grooves can be arranged around the entire circumference of the flow channel in embodiments and the condensate can always flow from there into a vertical flow section, almost any position of the flow sensor in space is possible.

According to a further, alternative embodiment, the first housing section and the second housing section are joined to one another in a joint plane in which the flow resistance arrangement is arranged. This results in a largely symmetrical and therefore simple construction of the flow sensor. In other words, the condensate drain arrangement has at least one flow section, which leads from the flow channel to at least one opening of at least one drain channel on an outside of the housing, the flow section receiving at least part of the flow resistance arrangement.

Furthermore, in advantageous embodiments, the flow resistance arrangement can be perpendicular to the flow path of the flow channel. Another preferred advantage is when the at least one flow section of the condensate drain arrangement lies in the plane of the parting line. This results in a particularly good drainage, which is central in the parting line level. The flow channel is free of projections, channels or grooves, resulting in an unobstructed flow. This results, for example, in a simple construction with a first component, which has the first housing section with the first pressure detection connection, and a second component, which has the second housing section with the second pressure detection connection. At this point it should be noted that other designs with more than two components for the first and second housing section are also possible in other embodiments. In addition, in other embodiments The first and second housing sections can also be formed integrally, i.e. in one piece, for example using a 3D printing manufacturing process. The flow resistance arrangement can also be designed in one piece with the housing.

In a preferred embodiment, the flow resistance arrangement has at least one flexible flap. In this case, the flow resistance arrangement can be formed in one piece in further embodiments. It can, for example, comprise a plastic film, preferably made of PET, which is fixed or held in a freely floating manner between the first housing section and the second housing section. For example, the thickness of the flow resistance arrangement can be 50 μm, with the width of the parting line preferably being 80 μm. In other embodiments, the plastic film can be between 20 μm and 200 μm thick and the parting line between 10 μm and 100 μm wide. The thickness of the flow resistance arrangement is advantageously essentially constant over the entire extension area.

In an advantageous embodiment, the flow resistance arrangement is essentially fixed in the plane of the parting line, preferably held in a freely floating manner. In contrast to a firm clamping between the housing sections, in which the flow resistance arrangement, which can be designed as a film, twists, no external forces act on the flexible flap of the flow resistance arrangement with this fixing. This prevents measurement inaccuracies. According to a further embodiment, the flow resistance arrangement has a plurality of recesses, into which corresponding projections, which are formed on the first and/or the second housing section, engage. The flow resistance arrangement is thus held radially at its recesses on the projections, with as few axial forces as possible acting on the flow resistance arrangement. Other holding mechanisms are also conceivable which contribute to the flow resistance arrangement being supported in a manner that is as free-floating as possible.

In an embodiment that has a particularly good measuring function, the flexible flap of the flow resistance arrangement can only be hinged on one side, namely on the side where the first and second pressure-sensing connections are also located. As a result, the turbulence is minimized in a normal flow and hardly ever occurs in the area of the openings of the pressure detection connections.

According to an advantageous embodiment, the condensate drain arrangement has at least one recess around the flow channel that is at least partially essentially ring-shaped or in the shape of the circumference of the flow channel. In this way, condensate can flow out of the at least one flow section into the annular recess and then be guided to the outside through a discharge channel. The ring-shaped recess also contributes to the fact that condensate can be reliably discharged to the outside, regardless of the orientation of the sensor in space. In addition, the construction is simple and easy to manufacture.

In a further embodiment, the condensate drain arrangement has at least one collection basin. This can effectively prevent condensate from incorrectly flowing back into the flow channel. The reservoirs may preferably be evenly spaced, e.g. H. be arranged equidistantly, for example at the annular recess along the circumference of the flow channel. This ensures that the condensate collects and can be reliably discharged. It is not absolutely necessary that the ring-shaped connection of the collection basins is present all around the circumference. Rather, it can be expedient for each segment section of the condensate drain arrangement to have a corresponding drain channel along the circumference of the flow channel, so that reliable draining of the condensate is ensured for all orientations of the flow sensor in space.

According to a further preferred embodiment, the condensate drain arrangement can be formed symmetrically to the plane of the parting line on the first housing section and on the second housing section. For example, a circumferential ring can be formed on both housing sections, which is connected to the flow channel via a plurality of vertical flow sections. A condensate drain arrangement can thus be formed in each of the two housing sections or only in one housing section. The same applies to the axial channels, which can be part of the condensate shut-off arrangement: the first and/or the second housing section can comprise such an axial channel arrangement, which is correspondingly connected to the peripheral sections and the one or more outlet channels via one or more vertical flow sections .

In preferred embodiments, a suction pump is arranged on the at least one outflow channel. The use of a suction pump enables a reliable suction function of condensate from the flow sensor even if the geometric position of a Drain channel is not completely given a drainage of the condensate by gravity. There can also be several suction pumps, each of which is arranged on a discharge channel.

According to a further embodiment, the at least one discharge channel is arranged in a discharge pipe, which protrudes at any angle from the peripheral surface of the housing. This increases the flexibility of the design.

According to a further aspect of the present invention, a sensor system for differential pressure measurement comprises a flow sensor having the following features: a housing comprising a flow channel along a flow path for a fluid, a flow resistance arrangement in the flow channel, a first pressure-sensing connection and a second pressure-sensing connection, and a condensate - Drainage arrangement comprising at least one drainage channel out of the housing. The sensor system also includes at least one pump arrangement on at least one outflow channel, which is set up to selectively remove liquid present in the condensate outflow arrangement from the flow sensor. The pump assembly preferably includes one or more pumps configured to suck the accumulated liquid out of the condensate drain assembly. It is particularly important here that the pump has sufficient suction or transport capacity and is suitable for use in the medical field. The pump arrangement can be detachably arranged directly on the discharge channel or can be detachably connected to it via a hose connection. In addition to the pump or pumps themselves, the pump arrangement can have one or more, preferably removable, reservoirs or containers which are used to receive the removed liquid that has been sucked out. Alternatively, the pump arrangement can have a drain.

At this point it should be noted that the pumping function of the pump arrangement does not affect the measurement by the flow sensor. Accordingly, an active or alternatively a passive removal of condensate liquid from the condensate closure arrangement has no negative influence on the function of the flow sensor.

In a preferred embodiment of the sensor system, the condensate drain arrangement is arranged at least partially around the flow channel and is adapted to allow a flow of condensate around the flow channel and outside of the flow channel. This allows for reliable pumping of accumulated liquid from the condensate shut-off assembly, thereby helping to ensure proper flow measurement. In other words, the condensate drain arrangement is formed at least partially, preferably completely, on the outer circumference of the flow channel.

In a further advantageous embodiment, the flow sensor has precisely one discharge pipe with discharge channel, which is arranged radially opposite the first pressure detection connection and the second pressure detection connection, the pump arrangement being arranged on exactly one discharge pipe. In other words, the discharge channel is opposite, preferably diametrically opposite, relative to an imaginary axis running along the center point of the flow channel. This ensures, for example, an optimized liquid removal in the case in which the flow sensor is spatially arranged in such a way that the pressure detection connections point essentially vertically upwards, against the direction of gravity, and the outflow channel is thus arranged essentially on the underside of the flow sensor. As a result, the removal of liquid by gravity is additionally supported by pumping out by means of a pump arrangement.

A further aspect of the present invention relates to a ventilation device for the artificial ventilation of a patient with a ventilation gas source, a ventilation line arrangement running between the ventilation gas source and a patient-side, proximal end, a valve arrangement comprising an inspiration valve and an expiration valve, a flow sensor arrangement for quantitatively detecting a gas flow in the Ventilation line arrangement, comprising at least one flow sensor, a pressure change arrangement for changing the gas pressure of the gas flowing in the ventilation line arrangement, and having a control device which is set up to control the operation of the pressure change arrangement on the basis of measuring probes of the flow sensor arrangement, the ventilation device furthermore a sensor system as described above at the patient-side, proximal end.

In further embodiments, such ventilation devices can have more than one flow sensor, namely at least one distal flow sensor further away from the patient and a proximal sensor closer to the patient. At least the proximal flow sensor is designed as described above.

The integration of the sensor system with a pump arrangement in the ventilation device makes it possible to integrate an intelligent pumping function into the control device of the ventilation device: the control device is therefore set up in such a way that a signal for pumping out is only given when there is liquid in the flow sensor . Such a state is detected in that a difference between a flow measurement at a predetermined pressure at the proximal flow sensor and a flow measurement at the distal flow sensor is determined and a corresponding signal is output when this difference exceeds a certain limit value. This limit then indicates that a certain amount of liquid has accumulated in the proximal flow sensor. Consequently, upon receipt of this signal, the controller will command the pump assembly of the proximal flow sensor to pump down.

• 1 eine perspektivische Längsschnittansicht durch eine Ausführungsform des erfindungsgemäßen Durchflusssensors längs einer Schnittebene ist, die die Strömungsbahn und die Mittelachsen von Druckerfassungsverbindung des Durchflusssensors enthält;
• 2 eine perspektivische Längsschnittansicht des Durchflusssensors aus 1 ist, wobei die Vertikalachse um 90° gedreht ist;
• 3 eine Detailansicht des in 1 gestrichelten Bereichs ist;
• 4 eine perspektivische Explosionsansicht des Durchflusssensors aus 1 ist;
• 5 eine perspektivische Längsschnittansicht durch eine weitere Ausführungsform des erfindungsgemäßen Durchflusssensors längs einer Schnittebene ist, die die Strömungsbahn und die Mittelachsen von Druckerfassungsverbindung des Durchflusssensors enthält;
• 6 eine perspektivische Längsschnittansicht des Durchflusssensors aus 5 ist, wobei die Vertikalachse um 90° gedreht ist;
• 7 eine Detailansicht des in 5 gestrichelten Bereichs ist;
• 8 eine perspektivische Explosionsansicht des Durchflusssensors aus 5 ist; und
• 9 eine Beatmungsvorrichtung mit einem Durchflusssensor gemäß der vorliegenden Erfindung zeigt.

Further advantages and embodiments are explained in more detail below with reference to the accompanying drawings, in which:

• 1 Figure 12 is a longitudinal sectional perspective view through an embodiment of the flow sensor of the present invention along a sectional plane containing the flow path and central axes of the pressure sensing junction of the flow sensor;
• 2 a perspective longitudinal sectional view of the flow sensor 1 with the vertical axis rotated 90°;
• 3 a detailed view of the in 1 dashed area;
• 4 Figure 12 shows an exploded perspective view of the flow sensor 1 is;
• 5 Figure 12 is a longitudinal sectional perspective view through another embodiment of the flow sensor of the present invention along a sectional plane containing the flow path and central axes of the pressure sensing junction of the flow sensor;
• 6 a perspective longitudinal sectional view of the flow sensor 5 with the vertical axis rotated 90°;
• 7 a detailed view of the in 5 dashed area;
• 8th Figure 12 shows an exploded perspective view of the flow sensor 5 is; and
• 9 shows a ventilator with a flow sensor according to the present invention.

1 shows a preferred embodiment of a flow sensor 1 according to the invention in a perspective longitudinal sectional view. The flow sensor 1 comprises a housing 2 which has a first housing section 3 and a second housing section 5 . The first housing section 3 and the second housing section 5 are joined together at a first flange 4 and a second flange 6, respectively, the joining plane having a parting line 12 and thus defining a parting line plane.

The housing 2 of the flow sensor 1 defines a flow channel 7 which completely penetrates the housing 2 along a flow path 8 which is straight in the illustrated embodiment. The flow path 8 is therefore a flow axis here, which does not necessarily have to be the case. Deviating from the exemplary embodiment shown, the flow path 8 can also have a curved course.

Within the flow channel 7, the first housing section 3 and the second housing section 5 each have a flow guide element 10, which is arranged at a distance from the first and second flange 4, 6 and is designed to ensure a fluid flow that is as uniform as possible within the flow channel 7 . It should be noted here that the expansion of the flow guide element 10 in the axial direction is only so far that no turbulence occurs in the area of the flow channel 7 relevant to the measurement.

The first housing section 3 and the second housing section 5 each have a connecting piece in the region of the first and second flange 4, 6, respectively. The connection piece of the first housing section 3 comprises a first pressure measurement connection 11 and the connection piece of the second housing section 5 comprises a second pressure measurement connection 13, which in the embodiment shown here are each aligned perpendicularly to the flow path 8 and parallel to the plane of the parting line 12. The first pressure detection connection 11 and the second pressure detection connection 13 open into the flow channel 7 so that a pressure prevailing in the flow channel 7 can be transmitted via corresponding lines (not shown) to pressure sensors (also not shown) and recorded there.

The flow channel 7 is essentially cylindrical in shape, with a larger diameter in the direction of the parting line 12 than further out towards the pipe section of the housing 2 . In the area of the openings of the first and second pressure sensing connection 11, 13 accordingly, the diameter of the flow channel 7 has a larger value.

The first housing section 3 and the second housing section 5 each have a double-walled design on the outside and comprise an outer tube 14 and an inner tube 15 , with an intermediate space 16 being formed between the outer tube 14 and the inner tube 15 . In order to avoid confusion or incorrect connection of the flow sensor 1 in medical use, the outer diameters of the first housing section 3 and the second housing section 5 are different.

A flow resistance arrangement 9 is arranged in the plane of the parting line 12 and is shown in the figures in its rest position, as unloaded by a fluid flow in the flow channel 7 as a flat structure with a plane of extension orthogonal to the flow path 8 . The flow resistance arrangement 9 comprises a flexible flap 21, which is essentially circular in shape and has an in 1 is articulated or suspended in the upper section on an outer circle of the flow resistance arrangement 9 . It should be noted here that the shape of the flexible flap 21 can also have other shapes, such as polygons, in particular rectangles, possibly also with spikes. If a fluid flow now flows through the flow channel 7, no matter in which direction, the flexible flap 21 is deflected relative to the joint section fixed to the housing two, so that the flow resistance arrangement 9 or the flexible flap 21 in the flow channel 7 acts like a throttle. As a result, different fluid pressures are formed in the flowing fluid upstream and downstream of the flexible flap 21, which pressures can be detected via the openings in the first pressure detection connection 11 and the second pressure detection connection 13 in the connected pressure sensors (not shown). A pressure difference in the flow channel 7 upstream and downstream of the flow resistance arrangement 9 can thus be measured and recorded in accordance with a previously performed calibration of the flow sensor 1 . The pressure difference is thus a measure of the fluid flow along the flow path 8 of the flow sensor 1.

The flow resistance arrangement 9 is fixed in the plane of the parting line 12 in such a way that the flow resistance arrangement 9 is arranged so to speak freely floating in the plane between the first housing section 3 and the second housing section 5 . For this purpose, the flow resistance arrangement 9 has recesses on its outer circumference which are seated on projections 19 which are formed on the second flange 6 in the illustrated embodiment. The projections 19 thus serve as a radial stop to the outside, so that the flow resistance arrangement 9 cannot move in the plane of the parting line 12 . The fixing of the flow resistance arrangement 9 in the axial direction is brought about by the parting line 12 . However, the flow resistance arrangement 9 is not clamped by the two flanges 4, 6 being pressed together. Rather, the flow resistance arrangement 9 can move very easily in the axial direction due to the geometric dimensions of the parting line 12. However, this movement does not affect the flow measurement, in particular because in the case of a fluid flow essentially only the flexible flap 21 moves or deflects in the axial direction in a pressure-relevant manner.

As already explained in the introduction, the accumulation of condensate within the flow channel 7 and in particular on the flow resistance arrangement 9 can lead to a falsification of the pressure difference measurement. For this purpose, the flow sensor 1 according to the invention has a condensate drain arrangement 20 which is arranged around the flow channel 7 in the area of the parting line 12 . As described above, the width of the parting line 12 adjacent to the flow channel 7 is greater than the thickness of the flow resistance arrangement 9, resulting in a flow section 25 along which condensate that has settled on the flow resistance arrangement 9, for example as drops or a film, radially can drain to the outside. This condensate flows into a cavity 20 of the condensate drain arrangement, which in the embodiment presented is designed as a ring at a predetermined distance around the flow channel 7 . The drainage of condensate through the flow section 25 between the flow channel 7 and the cavity 20 can take place along the entire circumference, and therefore the condensate drainage arrangement is effective in almost any orientation of the flow sensor 1 in space.

In order that the condensate that has accumulated in the cavity can flow off to the outside, the condensate drain arrangement 20 has a drain channel 18 which opens out via a drain pipe 17 . A pump (not shown) can be arranged on this drain pipe 17 to support the draining or for sucking off the condensate. in the in 1 illustrated embodiment, the second housing section 5 has a plurality of drain pipes 17, with the 1 shown with respect to the flow path 8 opposite the second pressure sensing connection 13. In embodiments, each downcomer 17 may include a pump assembly.

2 shows the flow sensor 1 in a similar view, rotated only by 90° around the axis of the flow path 8. For the sake of simplicity, reference is made to repetition of the description 1 omitted, but only discussed the differences. In 2 one can see in particular the formation of the flow guide elements 10 within the first housing section 3 and the second housing section 5, the extension that is important for the guide function being visible perpendicular to the viewing plane.

Furthermore, the 2 In the upper and lower sections, it can be seen that a drain pipe 17 extends from the second housing section 5 in each case. In addition, it is clearly visible here how the condensate drain arrangement 20 extends as an annular cavity around the flow channel 7, with the flow section 25 (vertical here) being arranged between the flow channel 7 and the circumferential annular cavity.

3 is an enlarged view of the in 1 dashed area shown and serves to show the condensate drain arrangement 20 in detail. In particular, one can see here how the flow resistance arrangement 9 is fixed in the parting line 12 between the first housing section 3 and the second housing section 5 . As described, the parting line 12 is slightly wider than the thickness of the flow resistance arrangement 9 embodied here as a plastic film. The width of the parting line 12 is preferably between 50 µm and 200 µm, more preferably between 75 µm and 150 µm, most preferably between 90 µm and 120 µm µm. The thickness of the plastic film is preferably between 20 μm and 80 μm, more preferably between 40 μm and 60 μm and most preferably 50 μm.

In 3 is also clearly visible how the flow resistance arrangement 9 is held or mounted in the radial direction. In the embodiment shown here, the second housing section 5 has a plurality of projections 19 which engage in corresponding recesses 22 which are formed in the first housing section 3 . The flow resistance arrangement 9 rests against the projection 19 in the radial direction from above, in the drawing, and is supported there as if against a stop. It should be noted that the flow resistance arrangement 9 has a recess 23 at the appropriate locations, as referred to below with reference to FIG 4 is explained in more detail.

The condensate that accumulates in the flow channel 7 from the fluid on the flow resistance arrangement 9 runs within the parting line 12 in the flow section of the condensate drain arrangement 20 into the annular cavity, from which the drain channel 18 runs outwards as described above. So that no condensate can run back into the flow channel 7 from the condensate drain arrangement 20, the condensate drain arrangement 20 can have one or more collecting basins which, for example, extend equidistantly around the circumference along the annular cavity. Furthermore, it is possible that a discharge channel 18 with a corresponding discharge pipe 17 is also located in the first housing section 3, as a result of which the discharge capacity of the condensate discharge arrangement is increased.

4 12 shows the flow sensor 1 of the embodiment of FIGS 1-3 . In addition in particular the 1 and the 2 the flow resistance arrangement 9 is shown here with its details. You can see the four recesses 23, which are distributed at equal intervals over the circumference. Furthermore, it can be seen that the articulation of the flexible flap 21 is directionally substantially aligned with the orientation of the pressure sensing connections 11,13. Corresponding (in 4 (not visible) projections 19 formed on the second flange 6 of the second housing section 5. In the present embodiment, the flow resistance arrangement 9 is therefore held freely floating in the radial direction by means of the projections 19 and the recesses 22 . In 4 one can also see the four visible drain pipes 17 on the second housing section 5, which extend radially outwards circumferentially at an angle of 60° and thus ensure that condensate can drain off essentially in any spatial arrangement of the flow sensor 1 in the room. As described above, each drain pipe 17 may include a pump assembly.

5 shows a further embodiment of the flow sensor 1 according to the invention in a perspective longitudinal sectional view 1 until 4 described first embodiment are identical, a repetition of the description of these components will be omitted. The difference from the first embodiment lies in a different design of the condensate drain arrangement 20, which in the embodiment described here has axial channels 24 which are defined in the flow channel 7 on its outer circumference. It should be noted that the number of axial channels 24 is relatively high here, so fewer axial channels 24 can also be formed in the flow channel 7, for example four or eight. The axial channels 24 are defined at the bottom of the flow channel 7 and range from the transition area between the smaller and the larger diameter of the flow channel 7 to the parting line 12. Condensate that has settled on the surfaces within the flow channel 7 or that has accumulated on the flow resistance arrangement 9, as in the first embodiment, runs here following the incline from up to the annular cavity, to which the drain channel 18 is connected. Here, too, the condensate discharge arrangement 20 has an annular shape, so that the axial channels 24 present in the circumferential direction open into it. Flow sections of the condensate drain arrangement 20 are also present here, which have a portion that is perpendicular to the flow path 8 .

6 FIG. 12 is a longitudinal sectional perspective view of the flow sensor 1 according to the embodiment of FIG 5 , wherein the flow sensor 1 is rotated by 90° around the axis of the flow path 8, similar to the illustration in FIG 2 . In 6 it can be seen that there is no axial channel 24 running in the longitudinal section plane, so that there is a radial distance between the annular cavity of the condensate drain arrangement 20 and the flow channel 7 in the longitudinal section plane. Similar to referring to 2 The embodiment described above has the housing 2 on a plurality of drain pipes 17 , these being arranged on the first housing section 3 in the embodiment shown here.

7 shows the detailed view that appears in 5 marked with the dashed rectangle. Here, too, it can be seen that the flow resistance arrangement 9 extends radially outwards approximately to the condensate outlet arrangement 20, with the axial channel 24 also extending radially there in the sectional plane, so that condensate can flow out via the condensate outlet arrangement 20 and the outlet channel 18 connected to it can expire.

8th shows the flow sensor 1 in the embodiment of FIG 5-7 in perspective exploded view. This representation is very similar to that of 4 , where the first preferred embodiment was described. Therefore, a repeated description of the identical components is omitted. The main difference is the design of the condensate drain arrangement 20 which, as described in detail above, has the plurality of circumferential axial channels 24 in the flow channel 7 . It can also be seen that the drain pipes 17 are formed on the first housing section 3 .

In 9 an embodiment of a ventilation device according to the invention is generally denoted by 100 . In the example shown, the ventilation device 100 is used for the artificial ventilation of a human patient 112 . Merely for the sake of completeness, it should be pointed out that the ventilation device 100 according to the invention can be accommodated as a mobile ventilation device 10 on a rollable frame 113 .

The ventilation device 100 has a device housing 114 in which--not visible from the outside because of the opaque housing material--a pressure-changing arrangement 116 and a control device 118 are accommodated.

The pressure change arrangement 116 is constructed in a manner known per se and has a ventilation gas source 115 in the form of a pump, a compressor or a blower, each of which can be controlled in a load-changing manner and therefore not only the introduction of ventilation gas into the ventilation device, but also the change in pressure of the introduced ventilation gas. The ventilation gas source 115 (gas source 115) can alternatively also be formed by a pressure vessel which can be connected to the device housing 114 of the ventilation device 100. The pressure-changing arrangement 116 can have the gas source 115 and optionally additionally--or alternatively in the case of a pressurized gas supply as the gas source--a reducing valve and the like. The ventilation device 100 also has an inspiration valve 120 and an expiration valve 122 in a manner known per se.

The control device 118 is usually implemented as a computer or microprocessor. It includes an in 9 storage device, not shown, in order to be able to store data necessary for the operation of the ventilation device 100 and to be able to call them up if necessary. In the case of network operation, the memory device can also be located outside of the device housing 114 and connected to the control device 118 by a data transmission connection. The data transmission connection can be formed by a cable or a radio link. However, in order to prevent disturbances in the data transmission connection from affecting the operation of the ventilation device 100, the memory device is preferably integrated into the control device 118 or at least accommodated in the same device housing 114 as the latter.

For the input of data into the ventilation device 100 or, more precisely, into the control device 118, the ventilation device 100 has a data input 124, which in 9 example shown is represented by a keyboard. As an alternative or in addition to the keyboard shown, the control device 118 can receive data via various data inputs, for example via a Network line, a radio link and/or via input connections 126.

In order to output data to the treating therapist, the ventilation device 100 can have an output device 128, in the example shown a screen.

The patient 112 is connected to the pressure change arrangement 116 via a ventilation line arrangement 130 for artificial ventilation. The patient 112 is intubated for this.

The ventilation line arrangement 130 has an inspiration tube 132 outside of the device housing 114 . The inspiration hose 132 can be interrupted and have a first inspiration hose 134 and a second inspiration hose 136 between which a conditioning device 138 can be provided for targeted humidification and, if necessary, temperature control of the fresh ventilation gas supplied to the patient 112 . The conditioning device 138 can be connected to an external liquid reservoir 140, via which water for humidification or else a drug, for example to inhibit inflammation or to widen the respiratory tract, can be supplied to the ventilation gas.

The ventilation line arrangement 130 has the expiration valve 122 and also an expiration hose 142, via which metabolized ventilation gas is blown out of the lungs of the patient 112 into the atmosphere.

The inspiration tube 132 is coupled to the inspiration valve 120, and the expiration tube 142 to the expiration valve 122. Only one of the two valves is open at a time to allow a gas flow to pass through. The actuation of valves 120 and 122 is also controlled by control device 118.

The control device 118 is designed to repeatedly update or determine ventilation operating parameters that characterize the ventilation operation of the ventilation device 100 during the ventilation operation in order to ensure that the ventilation operation is optimally matched to the patient 112 to be ventilated at all times is. For this purpose, the ventilation device 100 is connected to one or more sensors for data transmission, which monitor the condition of the patient and/or the operation of the ventilation device.

One of these sensors is a proximal flow sensor 1 which, in a Y-connector 145, detects the ventilation gas flow prevailing there in the ventilation line arrangement 130. The flow sensor 1 can be coupled to the input connections 126 of the control device 118 by means of a sensor line arrangement 146 . The sensor lead assembly 146 may, but need not, include electrical signal transmission lines. It can also have hose lines 143 which transmit the gas pressure prevailing on both sides of the flow sensor 1 in the direction of flow to the input connections 126 , where this is quantified by pressure sensors 127 . The flow sensor 1 is a differential pressure flow sensor as described above.

A further flow sensor 147 is provided in the device housing 114 and is referred to as the distal flow sensor 147 due to its greater distance from the patient 112 .

Due to the location of its attachment in the Y-connector 145, the proximal flow sensor 1, in contrast to the distal flow sensor 147, is basically also able to detect the flow of expiratory ventilation gas through the expiratory tube 142.

The correct function of the flow sensors 1 and 147 is essential for the correct operation of the ventilation device 10 and thus for the health of the patient 112.

It has been shown during operation that the proximal flow sensor 1 in particular is subject to a greater risk of error than the distal flow sensor 147 due to its proximity to the patient 112. The proximal flow sensor 1, through which expiratory ventilation gas also flows, is stronger than the distal flow sensor 147, for example moisture contained in the ventilation gas. This applies all the more if the distal flow sensor 147, as in the present example 9 is arranged upstream of the conditioning device 138 in the direction of inspiration and is therefore flowed through essentially only by dry inspiratory ventilation gas.

Signals from the proximal flow sensor 1 and the distal flow sensor 147 are evaluated in the control device 118 . If, for example, there is a difference between the measurement from the proximal flow sensor 1 and the measurement from the distal flow sensor 147 that exceeds a certain limit value, the control device 118 detects the presence of too much liquid in the proximal flow sensor 1 and initiates it by outputting a corresponding one Signal to the pump assembly of the proximal flow sensor 1 that the liquid from this is removed by suction or pumping out by means of the pump arrangement. In addition, an acoustic or visual alarm signal can be output on the output device 128 of the ventilation device 100, so that an operator is always informed about the current operating status of the device.

With the object according to the invention, a flow sensor is provided which improves or optimizes the outflow of condensate in the flow channel, thereby ensuring a reliable measuring function in all spatial positions and offering a simple construction.

Reference List

1

flow sensor

2

Housing

3

first housing section

4

first flange

5

second housing section

6

second flange

7

flow channel

8th

flow path

9

Drag assembly/flexible flap

10

flow guide element

11

first pressure sensing connection

12

parting line

13

second pressure sensing connection

14

outer tube

15

inner tube

16

space

17

drain pipe

18

drain channel

19

head Start

20

condensate drain arrangement

21

flexible flap

22

recess

23

recess

24

axial canal

25

river section

100

ventilation device

112

patient

113

frame

114

device housing

115

ventilation gas source

116

pressure change arrangement

118

control device

120

inspiratory valve

122

expiratory valve

124

data input

126

input port

127

pressure sensor

128

output device

130

breathing line arrangement

132

inspiratory tube

134

first inspiratory tube

136

second inspiratory tube

138

conditioning device

140

liquid supply

142

expiratory tube

143

hose lines

145

Y connector

146

Sensor Wiring Arrangement

147

distal flow sensor

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was 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.

Patent Literature Cited

• DE 2030775 [0003]
• WO 9106830 A1 [0003, 0006]
• US4932269A [0007, 0008]
• US20210162151A1 [0008]
• DE 4034176 A1 [0009]
• DE 102018204799 A1 [0010]

Claims (17)

Flow sensor (1) based on the differential pressure principle a housing (2) comprising a first housing section (3), a second housing section (5) and a flow channel (7) along a flow path (8) for a fluid through the first and second housing sections (3, 5), a flow resistance arrangement (9) in the flow channel (7), which is fixed to at least one of the first housing section (3) and the second housing section (5) and, a first pressure sensing connection (11) and a second pressure sensing connection (13), and a condensate drain arrangement (20) which has at least one drain channel (18) out of the housing (2) and at least one flow section (25) which is set up to allow a flow of condensate outside, preferably at least partially in the form of a flow channel circumference, around the flow channel (7) to allow the drain channel (18). Flow sensor (1) after claim 1 , characterized in that the condensate drain arrangement (20) has axial channels (24) in the flow channel (7), the at least one flow section (25) adjoining at least one axial channel (24). Flow sensor (1) after claim 1 or 2 , characterized in that the first housing section (3) and the second housing section (5) are joined together in a parting plane in which the flow resistance arrangement (9) is arranged. Flow sensor (1) according to one of the preceding claims, characterized in that a flow resistance arrangement (9) is essentially perpendicular to the flow path (8) of the flow channel (7). Flow sensor (1) according to one of claims 3 or 4 , characterized in that the at least one flow section (25) of the condensate drain arrangement (20) lies in the plane of the parting line. Flow sensor (1) according to one of the preceding claims, characterized in that the flow resistance arrangement (9) has at least one flexible flap (21). Flow sensor (1) according to one of the preceding claims, characterized in that the flow resistance arrangement (9) is designed in one piece. Flow sensor (1) according to one of claims 3 until 7 , characterized in that the flow resistance arrangement (9) fixed substantially in the plane of the parting line, is preferably kept freely floating. Flow sensor (1) according to one of the preceding claims, characterized in that the condensate drain arrangement (20) has at least one annular recess around the flow channel (7). Flow sensor (1) according to one of the preceding claims, characterized in that the condensate drain arrangement (20) has at least one collection basin. Flow sensor (1) after claim 10 , characterized in that the condensate drain arrangement (20) comprises a plurality of collection basins which are arranged equidistantly around the flow channel (7). Flow sensor (1) according to one of the preceding claims, characterized in that the at least one discharge channel (18) is arranged in a discharge pipe (17) which protrudes at any angle from the peripheral surface of the housing (2). Flow sensor (1) according to one of the preceding claims, characterized in that the flow section (25) accommodates at least part of the flow resistance arrangement (9). Sensor system for differential pressure measurement with a flow sensor that has the following features: a housing (2) comprising a flow channel (7) along a flow path (8) for a fluid, a flow resistance arrangement (9) in the flow channel (7), a first pressure sensing connection (11) and a second pressure sensing connection (13), and a condensate drain arrangement (20) which has at least one drain channel (18) out of the housing (2), and at least one pump arrangement on at least one drain channel (18), which is set up to selectively remove liquid present in the condensate drain arrangement (20) from the flow sensor (1). sensor system Claim 14 , characterized in that the condensate drain arrangement (20) is arranged at least partially around the flow channel (7) and adapted to a flow of condensate around the flow allow channel (7) and outside of the flow channel (7). sensor system Claim 14 or 15 , characterized in that the flow sensor (1) has exactly one outlet pipe (17) with an outlet channel (18), which is arranged radially opposite the first pressure detection connection (11) and the second pressure detection connection (13), and that the pump arrangement on the exactly one Drain pipe (17) is arranged. Ventilation device (100) for the artificial ventilation of a patient (112) with a ventilation gas source (115), a ventilation line arrangement (130) running between the ventilation gas source (115) and a patient-side, proximal end, a valve arrangement comprising an inspiration valve (120) and an expiration valve (122), a flow sensor arrangement for quantitatively detecting a gas flow in the ventilation line arrangement (130), comprising at least one flow sensor (1, 147), a pressure change arrangement (116) for changing the gas pressure of the gas flowing in the ventilation line arrangement (130), and having a Control device (118) which is set up to control the operation of the pressure change arrangement (116) on the basis of measuring probes of the flow sensor arrangement, characterized in that the ventilation device (100) further comprises a sensor system according to one of Claims 14 until 16 includes at the patient-side, proximal end.

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