CH701755B1 - Flow sensor. - Google Patents

Abstract

The flow measuring sensor (10) has a passage defining a cylindrical housing (10) with a first passage opening (13) and a second passage opening (29), a flow resistance (23) arranged in the passage of the housing which divides the housing into first and second passages Housing part (11 and 27) divided, a first connection point (17) with a connection to the interior of the first housing part (11), and a second connection point (19) with a connection to the interior of the second housing part. As a result, the first and second connection points (17, 19) are arranged at a distance from one another on the same housing part and / or a guide element (51) is arranged in the interior of the second housing part (27).

Description

Field of the invention

The invention relates to a flow sensor according to the preamble of claim 1. The flow sensor is used to determine the breathing air flow of a patient. When flowing through the flow sensor, the pressure difference on opposite sides of a flow resistance is measured via connected sensor tubes and a pressure gauge. The measurements obtained are used to determine the respiratory air flow and allow the observation of a patient about his breathing and / or the control of a ventilator.

State of the art

Flow sensors are known from the patent US 4 083 245. The content of this patent is incorporated by reference in the present application. This flow sensor is characterized by a cylindrical housing with a passage for the breathing air, a arranged in the passage of the housing flow resistance and connection points for sensor hoses on both sides of the flow resistance. The sensor hoses are led out of the cylindrical housing perpendicular to the flow direction. The cylindrical housing is usually constructed of two identical parts. Such housing parts are thus relatively easy and inexpensive to manufacture.

A major disadvantage of known flow sensor is the Abknickgefahr the sensor tubes. The kinking results in erroneous measurement results and thus incorrect patient status information. A control of a ventilator based on erroneous measurement results can result in medical complications for the patient.

Another disadvantage of known flow sensor results from the merger of the probe with flexible hose parts of the respirator. Since the position of these moving parts can influence the measurement results, they are subject to an increased measurement error. This, in turn, complicates the control of a ventilator and can lead to complications for the patient. Another disadvantage is based on the fact that the two housing parts are identical. As a result, an individual adaptation to patient-side and / or device-side air supply tubes is possible only via special adapter parts. Such additional parts increase the risk of mishandling and the dead volume.

Object of the invention

The object of the invention is to eliminate the disadvantages presented above and to produce an improved flow sensor.

description

According to the invention the object is achieved in a flow sensor according to the preamble of claim 1, characterized in that the first and second connection point for sensor tubes are arranged at a distance from each other on the same housing part. This makes it possible to direct the outgoing sensor hoses against the side of the device so that they can be routed directly to the pressure gauge. The sensor hoses are advantageously connected in parallel and led away with the device-side air supply tube. In use, no sensor tubes are directed against the patient. The patient side remains free of troublesome tubing, and the risk of kinking the tubing in use is reduced. Ventilation is thus safer and less complicated for the patient and the nursing staff.

Advantageously, the first connection point as the first connecting piece and the second connection point as a second connecting piece for the connection of a connecting line to at least one pressure sensor is formed. This ensures a robust connection between the sensor hose and the flow sensor. A buckling directly at the junction is also prevented.

In an advantageous embodiment, the connecting pieces are aligned substantially parallel to the longitudinal axis of the cylindrical housing. This allows the sensor tubes to be routed in parallel with the air supply tube in the direction of the ventilator and pressure gauge.

Advantageously, the housing is in two parts, wherein flanges are formed on the first housing part and on the second housing part for connecting the housing parts. This two-part construction is advantageous in the manufacture of the parts. It is possible, for example, to design the housing parts in an application-specific manner, that is, connection shapes and sizes can be selected and combined according to customer requirements. Conveniently, both housing parts may have the same or different shape and / or size on the opposite ends. Through ports (13, 29) with ports (i.e., ports) are adaptable to the shape and diameter of the connected air supply tubes. The housing parts are fixed by gluing, in particular ultrasonic gluing, pressing or welding of the flange surfaces (also called flange pressure surfaces).

In an advantageous embodiment, means for mutual relative alignment of the housing parts are provided on the flanges. These means are conveniently applied to the surfaces, i. Pressure surfaces, the flanges attached. The presence of such means simplifies the assembly of flow sensors and ensures mutually correct positioning. Only with correct positioning of the housing parts is an open connection between connection points and respective chambers in the housing interior guaranteed.

In an advantageous embodiment, means for cohesive connection formation are provided on the flanges. The cohesive connection is expediently impermeable to air, so that ventilation and pressure measurement are not impaired by leaks.

The means for cohesive connection formation advantageously consist of profile structures, in particular ultrasonic welding profiles. These agents can be processed by welding, pressing or gluing to cohesive connections. Preferably, ultrasonic bonding is used for the material connection of these profiles.

Advantageously, profile structures - consisting of elevations - and groove structures - consisting of depressions - arranged to receive material on the pressure surfaces of the first flange and the second flange complementary to each other, so that a maximum material connection when connecting the two flange pressure surfaces is achieved.

Advantageously, leads from the first connection point, a first connection to a first inside housing-side opening in the interior of the first housing part and from the second connection point, a second connection to a second inside housing-side opening in the interior of the second housing part. These connections pass through the housing wall. Construction and material should be combined and designed so that such a connection is possible, i.e. the wall thicknesses should be sufficiently high and the material should have a certain strength. The material used is advantageously made of plastic, in particular a thermoplastic, which is physiologically harmless and preferably transparent. Conveniently, the flow sensor is constructed so that the housing-side openings in the interior of the housing parts and the origin of the movable flap of the flow resistance during their use at the top, i. higher side, so that liquid and mucus can flow down the underside, without getting into the sensor tubes or affecting the function of the flap.

Advantageously, the compounds extend partially in the flange pressure surfaces and / or emerge as sealing surface side openings through the flange pressure surfaces. The connections may lie in sections in only one flange pressure surface. This has the following advantages: A peripheral arrangement of the connection points on a flange extension is possible, which also results in a free choice of position and connection angle of the sensor tubes on the flange extension.

Advantageously, the connections are partially formed as slots in the flange pressure surfaces and partly as channels through the housing parts. The combination of channels and slots simplifies the manufacture of the parts, for example by injection molding. Because slots and / or channels are structurally possibly necessary only on a flange pressure surface. As a result, the counterpart can possibly be made structurally simpler.

Advantageously, sealing surface side openings opening onto the flange pressure surfaces are formed by continuous surface structures, e.g. Elevation structures or groove structures, edged. As a result, in the assembled flowmeter sensor, a disturbing influence which distorts the measurement results is prevented by leaks.

Advantageously, sealing surface side openings on the first flange pressure surface, which form a connection to the interior of the first housing part, bordered together by a continuous structure, and sealing surface side openings on the second flange pressure surface, which form a connection to the interior of the second housing part, together by a framed second continuous structure; and the passage of the cylindrical housing is enclosed by a further continuous structure, said structures having opening groups, i. the said common edged openings, delimit each other. As a result, in the assembled flowmeter sensor, an interfering influence that distorts the measurement results is prevented by leaks between the various connection paths.

Advantageously, the housing-side openings in the interior of the housing parts in each case the same distance to the flow resistance are arranged opposite one another. This increases the measurement accuracy of the pressure difference.

Advantageously, both connections to the interior of the housing parts of equal length. This also increases the measurement accuracy of the pressure difference.

Advantageously, means for arranging the flow resistance are provided on the flange pressure surfaces. These may be pins, for example, which interact with recesses on the flow resistance.

Advantageously, the flanges have a diameter which is larger than the housing diameter. As a result, a peripheral arrangement of the connection points is possible, which also follows a free choice of position and connection angle of the sensor tubes.

Advantageously, the passage of the housing in the central part has an area of increased diameter, wherein the flow resistance is arranged within this area and divides the passage into two chambers. This is particularly advantageous for ventilation. Because this prevents that draining liquid and mucus affect the measurement noticeably. The movable flap can be constructed so large that, if it breaks off, it remains in the flow sensor and thus can not enter the respiratory tract of the patient.

According to the invention, the object of the invention is alternatively achieved in a flow sensor according to the preamble of claim 22, characterized in that a guide element is arranged in the interior of the second housing part. This makes it possible to influence the air flow in such a way that the flow flows through the sensor substantially uninfluenced by the position and bending of the length of hose lying in front of the passage opening (29). It is believed that existing flow or transverse flow fractions are reduced and the laminar flow rate through the guide element is increased. This makes it possible to measure a differential pressure which is independent of the position and bending of the tube piece lying in front of the passage opening (29). The measurement of the ventilation values and thus the ventilation control of a patient is thereby improved. The susceptibility to artificial respiration is thus reduced. In addition, the guide allows flow correction over a short distance. Since flow inhomogeneity has always been a problem, especially with short tube systems, the present embodiment additionally offers the advantage that the length of a tube system between the flowmeter and the lungs can be reduced without having to accept a deterioration of the measurement results. This in turn allows for a reduction in the dead volume. This is of particular importance to small patients with low lung volumes, such as children and neonates.

In one embodiment, such a guide element is arranged in the flow sensor according to claim 1 in the interior of the second housing part. This leads to the same advantages mentioned in the previous paragraph.

In one embodiment, the guide element consists of several interacting parts. As a result, flow conditions can be adapted to the respective situation.

Advantageously, the guide element extends in the flow direction in the housing passage and thereby subdivides the passage of the housing in passage chambers, so that the guide element has a plane of symmetry, which is spanned by the axis of the passage opening and the center of the housing interior opening. As a result of this arrangement of the guide element, which is symmetrical to the housing-side opening, an air flow which is symmetrical to the housing-internal opening is obtained equally. This results in better reproducible measurement results.

In a preferred embodiment, the guide element is formed as a small plate, which divides the passage of the housing part in sections into two mirror-image contiguous through chambers, which lie in their extension to the left and right of the openings. From an industrial point of view, it is interesting that a high degree of position insensitivity of the measurement results is achieved by a simple platelet shape of the guide element alone.

In a further preferred embodiment, the guide element is in the direction of the passage opening, i. to the passage opening or passage opening side, spaced from the inner housing to allow insertion of a piece of tubing, which in turn has a reduction of the dead volume result and thus is particularly advantageous for small patients with low lung volume.

In a preferred use of the flow sensor according to claim 1 or claim 22, the first housing part is connected to the device side and the second housing part on the patient side. This has the following advantages: Firstly, in connection with the device according to claim 1, the measuring tubes, which lead to the differential pressure gauge, can be led away from the patient directly and parallel to one another. The risk of this kinking is reduced, which increases comfort for the patient and nursing staff. On the other hand in connection with the device according to claim 22, the air flow of the exhaled air is aligned by a guide element. In this way, first, a movement-related positional influence on the differential pressure measurement results is reduced or eliminated. Secondly, it becomes possible to use a shorter tube system on the respiratory or patient side. This in turn results in a lower dead volume.

In summary, it can be emphasized that the two variants of the invention according to claim 1 and claim 22 and in particular their combination solve known problems, bring the location and length of the hose system with it.

Hereinafter, the invention with reference to the figures in a schematic representation will be described in more detail. It shows: <Tb> FIG. 1: <SEP> Perspective view of a flow sensor in three parts; <Tb> FIG. 2: <SEP> Longitudinal section through the composite flow sensor; <Tb> FIG. 3: <SEP> Device-side housing part in perspective view; <Tb> FIG. 4a: <SEP> Front view and top view of the device-side housing part; <Tb> FIG. 4b <SEP> Longitudinal section of the device-side housing part; <Tb> FIG. 5: <SEP> Patient-side housing part in perspective view; <Tb> FIG. 6a <SEP> front view and top view of the patient-side housing part; <Tb> FIG. 6b: <SEP> longitudinal sections of the patient-side housing part of FIG. 6a; <Tb> FIG. 7: <SEP> Patient-side housing part in perspective view with guide element <Tb> FIG. 6b: <SEP> longitudinal sections of the patient-side housing part of FIG. 6a; <Tb> FIG. 7: <SEP> Patient-side housing part in perspective view with guide element <Tb> FIG. 8a: <SEP> front view and top view of the patient-side housing part with guide element; <Tb> FIG. 8b: <SEP> Longitudinal sections of the patient-side housing part of FIG. 8a; <Tb> FIG. 9: <SEP> Longitudinal section through the composite flow sensor with guide element;

Fig. 1 shows a perspective view of a flow sensor in three parts: a first housing part 11, a flow resistor 23 and a second housing part 27. The first housing part 11 has a through hole 13 with connection to the device side air supply tube (not shown), a first flange 15 with a flange extension 16, two connection points 17, 19 each with a connecting piece 18, 20 and a first connecting channel 21 from the sealing surface of the first flange 15 to the interior of the first housing part 11. The flow resistance 23 consists of a thin membrane, the like is cut in that a movable central flap 25 is formed. The second housing part 27 has a through-opening 29 with connection to the patient-side air supply tube (not shown), a second flange 31 with flange extension 32, a second connection channel 33 (here only the sealing surface side opening of the connection channel) from the sealing surface of the second flange 31 to Interior of the second housing part 27. At the flange extension 32 of the second housing part 27 are two slots (first slot 35 and second slot 37) - as shown below - the connection of the connection points (first connection point 17 and second connection point 19) to the connection channels (First connecting channel 21 and second connecting channel 33) and thus allow the interior of the housing parts. Furthermore, on the opposing flange pressure surfaces (first flange pressure surface 15 and second flange pressure surface 31) pins 41 (see FIG. 4b) and mating recesses 39 are formed, which both the positioning of the flow resistance with respect to the housing parts and the mutual positioning of the two Ensure housing parts.

Fig. 2 shows the cohesive arrangement of the first housing part 11, the second housing part 27 and intermediate flow resistance 23. For cohesive arrangement, an ultrasonic welding connection 43 is used, which is airtight after welding the housing parts.

In Fig. 3, the first housing part is shown in a further perspective view. Here, the non-central arrangement of the sealing surface side opening of the first connection channel 21 between the connection points 17 and 19 is illustrated. In Fig. 4a is further seen that the connecting channel 21 leads to the interior of the first housing part 11. In this case, the housing-internal opening 12 lies centrally below the first flange extension 16.

As can be seen in FIGS. 4a and 4b, uninterrupted welding structures 45, formed as elevations, run along the outer edge of the sealing surfaces of the first flange 15 and its extension 16. In addition, the sealing surface side openings of the connection points 17, 19 and the connection channel 21 are bordered with the welding structure 45 so that on the one hand the sealing surface side opening of the second junction 19 is bordered with the welding structure and separated from the other the two sealing surface side openings of the first connection point 17 and of the first connection channel 21 are bordered with the welding structure 45. In addition, positioning pins 41 can be seen in FIGS. 4a and 4b. These are arranged on the flange pressure surface on a circle around the center of the housing passage.

In Fig. 5, the second housing part is shown in a further perspective view. The non-central arrangement of the second connection channel 33 with respect to the flange extension 32 can be seen. In Fig. 6a is further seen that the connecting channel 33 leads to the interior of the second housing part 27. In this case, the housing-inner-side opening 28 lies centrally below the second flange extension 32.

As can be seen in FIGS. 6 a, 6 b and 6 c, uninterrupted groove structures 47 run along the outer edge of the sealing surfaces of the second flange 31 and its extension 32. In addition, the sealing surface side openings of the slots 35, 37 and the connecting channel 33 are bordered with the groove structure 47 so that on the one hand, the sealing surface side opening of the first slot 35 is bordered with the groove structure and separated from the other, the two sealing surface side openings of the second slot 37 and of the second connection channel 33 are bordered with the groove structure 47. Furthermore, positioning recesses 39 can be seen in FIGS. 6a and 6c. These are arranged on the flange pressure surface on a circle around the center of the housing passage.

In the embodiment shown here, the flow resistance (23, Fig. 1) with its recesses 49 and the second housing part 27 with its recesses 39 on the pins 41 (Fig. 4a) of the first housing part 11 match second housing part 27 positioned to match each other as well as cohesively and airtight interconnected. In this cohesive arrangement, the first connection point 17, the first slot 35 and the first connection channel 21 are connected so that a gas pressure exchange between the interior of the first housing part 11 and a pressure sensor hose connected to the first connection point 17 is possible. In addition, the second connection point 19, the second slot 37 and the second connection channel 33 are connected so that a gas pressure exchange between the interior of the second housing part 27 and a sensor tube connected to the second connection point 19 is possible. By means of a pressure sensor it is possible with this arrangement, continuously or from time to time, to detect a pressure difference between the interiors of the first and second housing parts, i. on both sides of the flow resistance. The obtained measurements can be used to observe a patient and / or control a ventilator.

In a further embodiment, a guide element 51 is arranged in the interior of the second housing part 27. The guide element shown in Fig. 7, 8a, 8b and 9 is formed as a plate. This plate acts as a flow straightener and is aligned in the flow direction in the interior of the second housing part 27. As shown in FIGS. 8a and 8b, the housing passage is divided by the guide element 51 in sections into two chambers 53, 55. The guide element is arranged between the passage opening 29 and the second housing-side opening 28 in the interior of the second housing part. As can be seen in Fig. 8a, the wafer is aligned on the plane formed by the axis 57 of the through hole 29 and the center 59 of the opening 28. The guide element 53 is connected at two of its opposite edges via tabs with the cylindrical housing wall (Fig. 8b). In the direction of passage opening 29, the guide element is designed as a free-standing nose. According to FIG. 8 b, the guide element is spaced in the passage direction from the second opening 28 in the interior of the second housing part by approximately the diameter of that opening 28. FIG. 9 shows a section through the entire flow sensor. The guide element 51 is integrated in the second, patient-side housing part 27, while the two connecting pieces 18 (not shown) and 20 on the first, device-side housing part 11 originate from the flange extension.

Such a guide can also be integrated in commercial flow sensors. For example, such a guide element can be integrated as a variant in the known flow sensor according to patent document US4 083 245 (in particular according to FIG. 1 and claims 1-5).

Legend:

[0042] <tb> 10 <SEP> Cylindrical case <tb> 11 <SEP> First housing part <tb> 12 <SEP> First inside opening in the inside of the first case <tb> 13 <SEP> Through hole (or connecting hole) to the air supply pipe on the unit side <tb> 15 <SEP> First flange, with first flange pressure surface <tb> 16 <SEP> First flange extension, with first flange extension surface <tb> 17 <SEP> First connection point <tb> 18 <SEP> First spigot <tb> 19 <SEP> Second connection point <tb> 20 <SEP> Second connection piece <tb> 21 <SEP> First connection channel <Tb> 23 <September> flow resistance <Tb> 25 <September> flap <tb> 27 <SEP> Second housing part <tb> 28 <SEP> Second inside opening in the inside of the second housing part <tb> 29 <SEP> Through hole (or port called) to the patient-side air supply tube <tb> 31 <SEP> Second flange, with second flange pressure surface <tb> 32 <SEP> Second flange extension, with second flange extension surface <tb> 33 <SEP> Second connection channel <tb> 35 <SEP> First slot <tb> 37 <SEP> Second slot <Tb> 39 <September> recesses <Tb> 41 <September> pins <tb> 43 <SEP> Ultrasonic welding connection (here a superimposition of original weld profile elevation and original groove) <Tb> 45 <September> Ultrasonic welding profile <Tb> 47 <September> groove structure <Tb> 49 <September> recesses <Tb> 51 <September> vane <tb> 53 <SEP> First passage chamber <tb> 55 <SEP> Second passage chamber <tb> 57 <SEP> Axis of the through hole (29) <tb> 59 <SEP> Center of Housing Inside Opening (28)

Claims (25)

1. Flow sensor (10) with A passage defining a cylindrical housing (10) having a first passage opening (13) and a second passage opening (29), A flow resistance (23) arranged in the passage of the housing, which divides the housing into a first and a second housing part (11 and 27), - A first connection point (17) with a connection to the interior of the first housing part (11), and - A second connection point (19) with a connection to the interior of the second housing part, characterized in that the first and second connection points (17, 19) are arranged at a distance from each other on the same housing part. 2. Flow sensor according to claim 1, wherein the first connection point (17) as a first connecting piece (18) and the second connection point (19) as a second connecting piece (20) for connecting a connecting line to at least one pressure sensor is formed. 3. flow sensor according to claim 2, wherein the connecting pieces (18, 20) are aligned substantially parallel to the longitudinal axis of the cylindrical housing (10). 4. Flow sensor according to one of the preceding claims, wherein flanges with flange pressure surfaces (15, 16, 31, 32) are formed on the first housing part (11) and on the second housing part (27) for connecting the housing parts. 5. flow sensor according to claim 4, wherein means for mutual relative alignment of the housing parts (11, 27) are provided on the flanges. 6. Flow sensor according to one of claims 4-5 wherein means are provided for the cohesive connection formation on the flange pressure surfaces (15, 31). 7. flow sensor according to claim 6, wherein the cohesive connection formation on a weld, in particular a Ultraschallverschweissung based. 8. flow sensor according to one of claims 6-7, wherein the means for cohesive connection formation consist of groove and weld structure. 9. flow sensor according to claim 8, wherein groove and welding structure on the surfaces of the first flange (15,16) and the second flange (31, 32) are mutually complementarily arranged. 10. Flow sensor according to one of claims 4-9, wherein the compounds extend partially in the flange pressure surfaces and / or as sealing surface side openings (17, 19, 21, 33, 35, 37) exit through the flange pressure surface. 11. Flow sensor according to claim 10, wherein the compounds in part as slots (35, 37) in the flange pressure surfaces and partly as channels (21, 33) through the housing parts (11, 27) are formed. 12. Flow sensor according to one of claims 10-11, wherein the sealing surface side openings (17, 19, 21, 33, 35, 37), which open onto the flange pressure surfaces, by continuous groove structures (47) or profile elevation structures (45) are enclosed. 13. Flow sensor according to one of claims 10-12, wherein the sealing surface side openings (17, 21) of the first flange pressure surface, which form a connection to the interior of the first housing part, are jointly enclosed by a continuous structure, and wherein the sealing surface side openings (33, 37) of the second flange pressure surface, which form a connection to the interior of the second housing part, are jointly enclosed by a second uninterrupted structure; and wherein the passage of the cylindrical housing is enclosed by another continuous structure, and these structures being either groove structures (47) or welding structures (45). 14. Flow sensor according to one of claims 4-13, wherein means for arranging the flow resistance (23) are provided on the flange pressure surfaces (15, 31). 15. Flow sensor according to one of claims 4-14, wherein the flanges have a diameter which is greater than the housing diameter. 16. Flow sensor according to one of the preceding claims, wherein the two housing parts (11, 27) on the opposite ends have different shape or size. 17. Flow sensor according to one of the preceding claims, wherein from the first connection point (17) has a first connection to a first housing-side opening (12) in the interior of the first housing part (11) and of the second connection point (19) a second connection to a second Housing inside opening (28) in the interior of the second housing part (27) leads. 18. Flow sensor according to claim 17, wherein the housing-side openings (12, 28) in the interior of the housing parts (11, 27) in each case the same distance from the flow resistance (23) are arranged opposite one another. 19. Flow sensor according to one of the preceding claims, wherein the connections to the interior of the respective housing parts have the same length. 20. Flow sensor according to one of the preceding claims, wherein the passage of the housing in the central part has a region with an enlarged diameter, wherein the flow resistance (23) is arranged within this range. 21. Flow sensor according to one of the preceding claims, wherein a guide element is arranged in the interior of the second housing part (27). 22. flow sensor according to claim 21, wherein the guide element (51) consists of a plurality of cooperating parts. 23. Flow sensor according to one of claims 21-22, wherein the guide element extends in the flow direction in the housing passage, thereby dividing the passage of the housing into passage chambers, and wherein the guide element has a plane of symmetry which through the axis of the through hole (29) and the center the housing-inside opening (28) is clamped. 24. Flow sensor according to one of claims 21-23, wherein the guide element is formed as a plate which sections of the passage of the second housing part (27) divided into two mirror-image contiguous through chambers, which lie in their extension left and right of the housing-side opening (28) , 25. Flow sensor according to one of claims 21-24, wherein the guide element to the passage opening (29) is spaced from the second housing part to allow insertion of a piece of tubing.