Abstract
The present disclosure provides for a sensor system for determining a flow rate of a fluid flow within a fluid channel comprising an elastic segment arranged next to a rigid segment, wherein a first pair of electrodes is provided at the rigid segment and a second pair of electrodes is provided at the elastic segment of the fluid channel. The system further comprises a sensor unit for detecting a capacitance of the first and second electrode pairs, and a processing unit for calculating and monitoring a distance between the electrodes of the second electrode pair based on the detected capacitance of the first electrode pair and the second electrode pair, wherein the first electrode pair is in contact with the rigid segment and the second electrode pair is in contact with the elastic segment. Moreover, a respective method for determining a flow rate of a fluid flow within a fluid channel is provided by the present disclosure, as well as a use of the sensor system.
Claims
1. A sensor system for determining a flow rate of a fluid flow within a fluid channel, the system comprising: a fluid channel comprising an elastic segment arranged next to at least one rigid segment, at least a first pair of electrodes provided at said rigid segment of the fluid channel, the electrodes of the first pair of electrodes being arranged opposing each other, at least a second pair of electrodes provided at said elastic segment of the fluid channel, the electrodes, of the second pair of electrodes being arranged opposing each other, a sensor unit for detecting a capacitance of the first pair of electrodes and the second pair of electrodes, and a processing unit for calculating and monitoring a distance between the electrodes of the second pair of electrodes based on the detected capacitance of the first pair of electrodes and the second pair of electrodes, wherein the first pair of electrodes is in contact with said rigid segment of the fluid channel and the second pair of electrodes is in contact with said elastic segment of the fluid channel.
2. The sensor system according to claim 1, wherein the first pair of electrodes is in contact with an outer circumference of a wall of the fluid channel at the rigid segment and the second pair of electrodes is in contact with the outer circumference of the wall of the fluid channel at the elastic segment, wherein the first pair of electrodes is attached to the outer circumference of the wall of the fluid channel at the rigid segment and the second pair of electrodes is attached to the outer circumference of the wall of the fluid channel at the elastic segment.
3. The sensor system according to claim 1, wherein the electrodes of the second pair of electrodes are movably arranged to one another.
4. The sensor system according to claim 1, wherein the electrodes of the second pair of electrodes are arranged parallel to one another.
5. The sensor system according to claim 1, wherein the electrodes of the second pair of electrodes are arranged in an inclined manner to one another.
6. The sensor system according to claim 1, wherein the sensor system further comprises at least a third pair of electrodes provided at a further rigid segment of the fluid channel, with the electrodes of the third pair of electrodes being arranged opposing each other, and wherein the elastic segment of the fluid channel is arranged in between the rigid segment exhibiting the first pair of electrodes and the further rigid segment exhibiting the third pair of electrodes.
7. The sensor system according to claim 6, wherein the third pair of electrodes is in contact with an outer circumference of the wall of the fluid channel at the further rigid segment, wherein the third pair of electrodes is attached to the outer circumference of the wall of the fluid channel at the further rigid segment.
8. The sensor system according to claim 6, wherein the sensor system further comprises at least a fourth pair of electrodes provided at a further elastic segment of the fluid channel, with the electrodes of the fourth pair of electrodes being arranged opposing each other, and wherein the further rigid segment is arranged between the elastic segment and the further elastic segment.
9. The sensor system according to claim 8, wherein the fourth pair of electrodes is in contact with an outer circumference of the wall of the fluid channel at the further elastic segment, wherein the fourth pair of electrodes is attached to the outer circumference of the wall of the fluid channel at the further elastic segment.
10. The sensor system according to claim 1, wherein the processing unit is adapted to determine a flow rate of the fluid flow within the fluid channel based on a distance between the electrodes of the second pair of electrodes over time.
11. A method for determining a flow rate of a fluid flow within a fluid channel by means of the sensor system of claim 1, the method comprising the steps of: detecting a capacitance of the first pair of electrodes, detecting a capacitance of the second pair of electrodes, calculating a distance between the electrodes of the second pair of electrodes based on the detected capacitance of the first pair of electrodes and the capacitance of the second pair of electrodes, and determining a flow rate of the fluid flow within the fluid channel based on a difference in distance between the electrodes of the second pair of electrodes over time.
12. The method according to claim 11, wherein the distance between the electrodes of the second pair of electrodes is calculated by means of the following equation wherein d.sub.1st=distance between the electrodes of the first pair of electrodes; A.sub.1st=surface area of the electrodes of the first pair of electrodes; d.sub.2nd=distance between the electrodes of the second pair of electrodes; A.sub.2nd=surface area of the electrodes of the second pair of electrodes; C.sub.1st=detected capacitance of the first pair of electrodes; and C.sub.2nd=detected capacitance of the second pair of electrodes.
13. The method according to claim 11, wherein a difference in distance between the electrodes of the second pair of electrodes over time reflects a change of fluid pressure within the elastic segment of the fluid channel.
14. The method according to claim 11, wherein an elasticity of the elastic segment of the fluid channel is adjusted based on the expected flow rate within the fluid channel.
15. A use of the sensor system according to claim 1 for determining a flow rate of a fluid flow within a fluid channel, wherein a movement of the electrodes of the second pair of electrodes towards or away from each other represents a direct measure of a change in fluid pressure of the fluid flowing within the fluid channel, which change in fluid pressure can be calculated into a flow rate of the fluid flowing within the fluid channel.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0043] FIG. 1A is a schematic functional illustration of a sensor system according to an embodiment of the present disclosure in a cross-sectional view, without fluid flow within its fluid channel;
[0044] FIG. 1B is a schematic functional illustration of the sensor system according to the embodiment as shown in FIG. 1A in a cross-sectional view, with fluid flow within its fluid channel;
[0045] FIG. 2A is a schematic functional illustration of a sensor system according to a second embodiment of the present disclosure in a cross-sectional view, without fluid flow within its fluid channel;
[0046] FIG. 2B is a schematic functional illustration of the sensor system according to the second embodiment as shown in FIG. 2A in a cross-sectional view, with fluid flow within its fluid channel;
[0047] FIG. 3A is a schematic functional illustration of a sensor system according to a third embodiment of the present disclosure in a cross-sectional view, without fluid flow within its fluid channel;
[0048] FIG. 3B is a schematic functional illustration of the sensor system according to the third embodiment as shown in FIG. 3A in a cross-sectional view, with fluid flow within its fluid channel; and
[0049] FIG. 4 is a flowchart of a method according to an embodiment of the present disclosure.
LIST OF REFERENCE SIGNS
[0050] 1, 1′, 1″ sensor system [0051] 2; 2′, 2″ fluid channel [0052] 21 rigid segment of the fluid channel [0053] 22, 22′, 22″ elastic segment of the fluid channel [0054] 23 rigid segment of the fluid channel [0055] 24, 24′, 24″ wall of the fluid channel [0056] 25, 25′, 25″ outer circumference of the wall of the fluid channel [0057] 3 fixed electrode pair/1.sup.st pair of electrodes [0058] 31 fixed electrode of the fixed electrode pair [0059] 32 opposing fixed electrode of the fixed electrode pair [0060] 4, 4′, 4″ moveable electrode pair/2.sup.nd pair of electrodes [0061] 41, 41″ moveable electrode of the moveable electrode pair [0062] 42, 42″ opposing moveable electrode of the moveable electrode pair [0063] 41′ fixed electrode of the moveable electrode pair [0064] 42′ moveable electrode of the moveable electrode pair [0065] 5 further fixed electrode pair/3.sup.rd pair of electrodes [0066] 51 fixed electrode of the further fixed electrode pair [0067] 52 opposing fixed electrode of the further fixed electrode pair [0068] 6 bidirectional fluid flow [0069] 7 unidirectional fluid flow [0070] A.sub.1st surface area of the electrodes of the fixed electrode pair [0071] A.sub.2nd, A′.sub.2nd, A″.sub.2nd surface area of the electrodes of the moveable electrode pair [0072] A.sub.3rd surface area of the electrodes of the further fixed electrode pair [0073] d.sub.1st distance between the electrodes of the fixed electrode pair [0074] d.sub.2nd, d′.sub.2nd, d″.sub.2nd distance between the electrodes of the moveable electrode pair [0075] d.sub.3rd distance between the electrodes of the fixed electrode pair [0076] S1 method step [0077] S2 method step [0078] S3 method step [0079] S4 method step
DETAILED DESCRIPTION
[0080] FIGS. 1A and 1B show a part of a sensor system 1 according to a first embodiment of the present disclosure. Here, it is pointed out that a sensor unit and a processing unit in general being part of the sensor system 1 of the present disclosure are not illustrated in the drawings for the sake of simplification. However, it is to be noted that the sensor unit and the processing unit are interconnected and are connected to the respective electrodes of the sensor system 1. Now, the shown part of the sensor system 1 comprises a tubular fluid channel 2 and a first pair 3 of electrodes 31, 32 at a rigid segment 21 of the fluid channel 2, with the electrodes 31, 32 being fixed with respect to each other and attached to, e.g. printed onto, an outer circumference 25 of a wall 24 of the fluid channel 2 at the rigid segment 21. Furthermore, the sensor system 1 comprises a second pair 4 of electrodes 41, 42 at an elastic segment 22 of the fluid channel 2, with the electrodes 41, 42 being arranged in a moveable manner with respect to each other and attached to, e.g. printed onto, an outer circumference 25 of a wall 24 of the fluid channel 2 at the elastic segment 22. Accordingly, a bidirectional flow 6 of a fluid within the fluid channel 2 can be measured through change of capacitance of the electrode pair 4 caused by the change in distance between these electrodes 41, 42. This change in distance is generated by elastic deformation of the elastic segment 22 caused by an increase of fluid pressure of a fluid flowing within the fluid channel 2. Here, at least the electrodes 41, 42 of the second electrode pair 4 are made of a stretchable material, or in a stretchable fashion, in order to be able to compensate for any expansion/contraction of the elastic segment 22. Moreover, the sensor system 1 further comprises a third pair 5 of electrodes 51, 52 at a further rigid segment 23 of the fluid channel 2, with the electrodes 51, 52 being fixed with respect to each other and attached to an outer circumference 25 of a wall 24 of the fluid channel 2 at the rigid segment 23. Here, the third pair 5 of electrodes 51, 52 is optional and is not necessarily required for carrying out the present disclosure; however, providing the third electrode pair 5 can account for the detection of a further change of the fluid flowing within the fluid channel 2. Accordingly, in FIGS. 1A and 1B, the part of the fluid channel 2 show in these illustrations comprises the first rigid segment 21, the elastic segment 22 and the further rigid segment 23, wherein transition areas between those segments are without substantial interruption, and the wall 24 of the fluid channel 2 is substantially continuous, in particular in order to avoid any disturbances of the fluid flowing inside the fluid channel 2.
[0081] As can be gathered from FIGS. 1A and 1B, a diameter of the fluid channel 2 at the elastic segment 22 is smaller than a diameter at the rigid segment 21 or as a diameter at the rigid segment 23. The difference in diameters can also be gathered from FIGS. 1A and 1B in the difference in distances between the respective electrodes, i.e. a distance d.sub.1st between the electrodes 31, 32 of the first pair 3 of electrodes 31, 32 provided at the left rigid segment 21 is larger than a distance d.sub.2nd between the electrodes 41, 42 of the second pair 4 of electrodes 41, 42 provided at the elastic segment 22 arranged in between the rigid segment 21 on the left side and the further rigid segment 23 on the right side of FIGS. 1A and 1B. Also, a distance d.sub.3rd between the electrodes 51, 52 of the third pair 5 of electrodes 51, 52 provided at the rigid segment 23 arranged at the right side in the drawings is larger than a distance d.sub.2nd between the electrodes 41, 42 of the second pair 4 of electrodes 41, 42 provided at the elastic segment 22 arranged in between the rigid segments 21, 23. In the present case, the distances d.sub.1st and d.sub.3rd of the rigid segments 21, 23, i.e. their diameters, coincide with each other, for the sake of simplification; the distances d.sub.1st and d.sub.3rd of the rigid segments 21, 23, however, can also differ from each other, as long as their exact dimensions are known. In FIGS. 1A and 1B, the different segments 21, 22, 23 are illustratively separated from each other by means of linear dotted lines.
[0082] In FIG. 1A, the sensor system 1 may already comprise a fluid, such as a liquid to be measured, inside the fluid channel 2. However, FIG. 1A shows an initial state of the sensor system 1, in which there is no fluid flow within the fluid channel 2. In FIG. 1B, on the contrary, fluid flow 6 is present within the fluid channel 2, which can be gathered by the enlarged distance d.sub.2nd, which can also be referred to as d.sub.2nd_moved, between the electrodes 41, 42 attached to the outer circumference 25 of the wall 24 of the fluid channel 2 at the elastic segment 22, compared to the distance d.sub.2nd between the electrodes 41, 42 in the initial state as depicted in FIG. 1A, which can also be referred to as d.sub.2nd_unmoved. Here, since rigid segments 21, 23 including respective electrode pairs 3, 5 are provided on both sides of the elastic segment 22, the fluid flow 6 to be measured can flow in either direction within the fluid channel 2, since, thus, either electrode pair 3, 5 can be used as reference value. In this regard, it can be gathered from the differing distances d.sub.2nd between the electrodes 41, 42 in the initial state as depicted in FIG. 1A and the enlarged state as depicted in FIG. 1B that FIG. 1A shows a state of the sensor system 1 before expansion, and that FIG. 1B shows a state of the sensor system 1 during fluid flow 6, i.e. after expansion of the elastic segment 22.
[0083] As can also be gathered from FIGS. 1A and 1B, the surface areas A.sub.1st of the electrodes 31, 32 of the first pair 3 of electrodes 31, 32, illustrated in the drawings of FIGS. 1A and 1B in a lateral dimension of the surface area A.sub.1st, coincide with each other, in order to achieve a clear capacitor relationship between these electrodes. Similarly thereto, the surface areas A.sub.2nd of the electrodes 41, 42 of the second pair 4 of electrodes 41, 42 coincide with each other, and the surface areas A.sub.3rd of the electrodes 51, 52 of the third pair 5 of electrodes 51, 52 also coincide with each other, for the same reason. Thus, based on the above described equation 8, the distance d.sub.2nd between the electrodes 41, 42 of the second electrode pair 4, i.e. the only moveable electrode pair in the present embodiment compared to the fixed electrode pairs 3, 5, can be calculated based on the measured capacitances of the fixed electrode pairs 3, 5. Repeating this calculation over time results in a timely progression of the distance d.sub.2nd, which timely progression represents a change of fluid pressure of the fluid flowing within the elastic segment 22 of the fluid channel 2. Thus, monitoring the timely progression of the distance d.sub.2nd corresponds to the monitoring of a timely progression of the fluid pressure of the fluid flowing within the elastic segment 22 of the fluid channel 2.
[0084] In FIGS. 1A and 1B, the electrodes 31, 32, 41, 42, 51, 52 of the electrode pairs 3, 4, 5 are depicted as plate-like components in a cross-sectional view. Here, as an example, the electrodes 31, 32, 41, 42, 51, 52 of the electrode pairs 3, 4, 5 can have a generally plate-like shape, which shape can follow the tubular curvature of the outer circumference 25 of the wall 24 of the fluid channel 2 at least in part. Here, the overall dimensions and shapes of the opposing electrodes 31 and 32, 41 and 42, 51 and 52 correspond to each other, in order to achieve a clear capacitor relationship between these electrodes 31 and 32, 41 and 42, 51 and 52 of each electrode pair 3, 4 and 5.
[0085] In FIGS. 2A and 2B, a sensor system 1′ in accordance with a second or modified embodiment of the sensor system as described herein is depicted. Here, there is a significant difference compared to the sensor system 1 as shown in FIGS. 1A and 1B in that the moveable electrode pair is implemented by means of a pair 4′ of electrodes 41′, 42′ consisting of a fixed electrode 41′ and a moveable electrode 42′. This can also be gathered from FIGS. 2A and 2B when comparing the change in diameter d′.sub.2nd between the electrodes 41′, 42′ in an initial state as depicted in FIG. 2A and in an enlarged state as depicted in FIG. 2B. The remaining parts of the sensor system 1′ of the second embodiment are basically identical to the respective parts of the sensor system 1 as illustrated in FIGS. 1A and 1B and as described above. For the sake of completeness, it is pointed out that FIGS. 2A and 2B show only a part of the sensor system 1′ according to the second embodiment of the present disclosure, wherein a sensor unit and a processing unit in general being part of the sensor system 1′ of the present disclosure are again not illustrated in the drawings for the sake of simplification. However, it is to be noted that the sensor unit and the processing unit are interconnected and are connected to the respective electrodes of the sensor system 1. The part of the sensor system 1′ shown in FIGS. 2A and 2B exhibits a tubular fluid channel 2′ and a first pair 3 of electrodes 31, 32 at a rigid segment 21 of the fluid channel 2′, with the electrodes 31, 32 being fixed with respect to each other and attached to an outer circumference 25′ of a wall 24′ of the fluid channel 2′ at the rigid segment 21. Furthermore, the sensor system 1′ comprises a second pair 4′ of electrodes 41′, 42′ at an elastic segment 22′ of the fluid channel 2′, with the electrodes 41′, 42′ being arranged opposing each other, and wherein the electrode 41′ constitutes a fixed electrode 41′ and the electrode 42′ constitutes a moveable electrode 42′ arranged in moveable manner with respect to the fixed electrode 41′. Here, both electrodes 41′ and 42′ are attached to an outer circumference 25′ of a wall 24′ of the fluid channel 2′ at the elastic segment 22′.
[0086] Accordingly, the flow 6 of a fluid within the fluid channel 2′ can be measured through change of capacitance of the electrode pair 4′ caused by the change in distance between these electrodes 41′, 42′. This change in distance is generated by elastic deformation of the elastic segment 22′ caused by an increase of fluid pressure of a fluid flowing within the fluid channel 2′. Moreover, and similar to the sensor system 1 as illustrated in FIGS. 1A and 1B, the sensor system 1′ further comprises a third pair 5 of electrodes 51, 52 at a further rigid segment 23 of the fluid channel 2′, with the electrodes 51, 52 being fixed with respect to each other and attached to an outer circumference 25′ of a wall 24′ of the fluid channel 2′ at the rigid segment 23. Here again, the third pair 5 of electrodes 51, 52 is optional and is not necessarily required for carrying out the present disclosure; however, providing the third electrode pair 5 can account for the detection of a further change of the fluid flowing within the fluid channel 2′. Accordingly, in FIGS. 2A and 2B, the part of the fluid channel 2′ show in these illustrations comprises the first rigid segment 21, the elastic segment 22′ and the further rigid segment 23, wherein transition areas between those segments are without substantial interruption, and the wall 24′ of the fluid channel 2′ is substantially continuous, in particular in order to avoid any disturbances of the fluid flowing inside the fluid channel 2′.
[0087] As can be gathered from FIGS. 2A and 2B, a diameter of the fluid channel 2′ at the elastic segment 22′ is smaller than a diameter at the rigid segment 21 or as a diameter at the rigid segment 23. The difference in diameters can also be gathered from FIGS. 2A and 2B in the difference in distances between the respective electrodes, i.e. a distance d.sub.1st between the electrodes 31, 32 of the first pair 3 of electrodes 31, 32 provided at the left rigid segment 21 is larger than a distance d′.sub.2nd between the electrodes 41′, 42′ of the second pair 4′ of electrodes 41′, 42′ provided at the elastic segment 22′ arranged in between the rigid segment 21 on the left side and the further rigid segment 23 on the right side of FIGS. 2A and 2B. Also, a distance d.sub.3rd between the electrodes 51, 52 of the third pair 5 of electrodes 51, 52 provided at the right rigid segment 23 is larger than a distance d′.sub.2nd between the electrodes 41′, 42′ of the second pair 4′ of electrodes 41′, 42′ provided at the elastic segment 22′ arranged in between the rigid segments 21, 23. In the present case, the distances d.sub.1st and d.sub.3rd of the rigid segments 21, 23, i.e. their diameters, coincide with each other, for the sake of simplification; the distances d.sub.1st and d.sub.3rd of the rigid segments 21, 23, however, can also differ from each other, as long as their exact dimensions are known. In FIGS. 2A and 2B, the different segments 21, 22′, 23 are again illustratively separated from each other by means of linear dotted lines.
[0088] In FIG. 2A, the sensor system 1′ may already comprise a fluid, such as a liquid to be measured, inside the fluid channel 2′. However, FIG. 2A shows an initial state of the sensor system 1′, in which there is no fluid flow within the fluid channel 2′. In FIG. 2B, on the contrary, fluid flow 6 is present within the fluid channel 2′, which can be gathered by the enlarged distance d′.sub.2nd, which can also be referred to as d′.sub.2nd_moved, compared to the distance d′.sub.2nd between the electrodes 41′, 42′ in the initial state as depicted in FIG. 2A, which can also be referred to as d′.sub.2nd_unmoved. Here, since rigid segments 21, 23 including respective electrode pairs 3, 5 are provided on both sides of the elastic segment 22′, the fluid flow 6 to be measured can flow in either direction within the fluid channel 2′, since, thus, either electrode pair 3, 5 can be used as reference value. In this regard, it can be gathered from the differing distances d′.sub.2nd between the electrodes 41′, 42′ in the initial state as depicted in FIG. 2A and the enlarged state as depicted in FIG. 2B that FIG. 2A shows a state of the sensor system 1′ before expansion, and that FIG. 1B shows a state of the sensor system 1′ during fluid flow 6, i.e. after expansion of the elastic segment 22′. As already described above, due to the fact that the electrode 41′ is constituted by a fixed electrode, and the respective part of the wall 24′ of the fluid channel 2′ is, thus, also fixedly arranged, the lower part of the wall 24′ of the fluid channel 2′ at which the loveable electrode 2′ is arranged is the part of the fluid channel 2′ which expands in line with the fluid pressure within the fluid channel 2′.
[0089] As can also be gathered from FIGS. 2A and 2B, the surface areas A.sub.1st of the electrodes 31, 32 of the first pair 3 of electrodes 31, 32, illustrated in the drawings of FIGS. 2A and 2B in a lateral dimension of the surface area A.sub.1st, coincide with each other, in order to achieve a clear capacitor relationship between these electrodes. Similarly thereto, the surface areas A′.sub.2nd of the electrodes 41′, 42′ of the second pair 4′ of electrodes 41′, 42′ coincide with each other, and the surface areas A.sub.3rd of the electrodes 51, 52 of the third pair 5 of electrodes 51, 52 also coincide with each other, for the same reason. Thus, based on the above described equation 8, which is to be adapted to the presently used reference signs accordingly, the distance d′.sub.2nd between the electrodes 41′, 42′ of the second electrode pair 4′, i.e. the only electrode pair in the present embodiment with variable distance in between electrodes compared to the fixed electrode pairs 3, 5, can be calculated based on the measured capacitances of the fixed electrode pairs 3, 5. Repeating this calculation over time results in a timely progression of the distance d′.sub.2nd, which timely progression represents a change of fluid pressure of the fluid flowing within the elastic segment 22′ of the fluid channel 2′. Thus, monitoring the timely progression of the distance d′.sub.2nd corresponds to the monitoring of a timely progression of the fluid pressure of the fluid flowing within the elastic segment 22′ of the fluid channel 2′.
[0090] In FIGS. 2A and 2B, the electrodes 31, 32, 41′, 42′, 51, 52 of the electrode pairs 3, 4′, 5 are depicted as plate-like components in a cross-sectional view. Here again, as an example, the electrodes 31, 32, 41′, 42′, 51, 52 of the electrode pairs 3, 4′, 5 can have a generally plate-like shape, which shape can follow the tubular curvature of the outer circumference 25′ of the wall 24′ of the fluid channel 2′ at least in part. Here, the overall dimensions and shapes of the opposing electrodes 31 and 32, 41′ and 42′, 51 and 52 correspond to each other, in order to achieve a clear capacitor relationship between these electrodes 31 and 32, 41′ and 42′, 51 and 52 of each electrode pair 3, 4′ and 5.
[0091] FIGS. 3A and 3B show a part of a sensor system 1″ according to a third embodiment of the present disclosure. Here again, a sensor unit and a processing unit being, in general, part of the sensor system 1″ of the present disclosure are not illustrated in the drawings for the sake of simplification. However, it is to be noted that the sensor unit and the processing unit of the presently described embodiment are interconnected and are connected to the respective electrodes of the sensor system 1″. Now, the part of the sensor system 1″ shown in FIGS. 3A and 3B comprises a tubular fluid channel 2″ and a first pair 3 of electrodes 31, 32 arranged at a rigid segment 21 of the fluid channel 2′, with the electrodes 31, 32 being fixed with respect to each other and attached to an outer circumference 25″ of a wall 24″ of the fluid channel 2″ at the rigid segment 21. Furthermore, the sensor system 1″ comprises a second pair 4″ of electrodes 41″, 42″ at an elastic segment 22″ of the fluid channel 2″, with the electrodes 41″, 42″ being arranged in a moveable manner with respect to each other and attached to an outer circumference 25″ of a wall 24″ of the fluid channel 2″ at the elastic segment 22″. Here, even though the fluid channel 2″ provides for a tubular shape, the elastic segment 22″ does not exhibit a continuous diameter but rather a converging shape with a decreasing diameter when viewed from left to right in FIGS. 3A and 3B, contrary to the above-described first and second embodiments. Thus, the elastic segment 22″ constitutes a nozzle-like shape, with the wall 24″ reducing its diameter so that, in cross-section, the wall 24″ converges into a sharp angle. In an initial state as illustrated in FIG. 3A, i.e. in a state in which no fluid flow is present within the fluid channel 2″, the wall 24″ actually closes up at the downstream end of the elastic segment 22″, thereby constituting an angle, in cross-section, of e.g. 30°-40°, depending on the length of the elastic segment 22″. Accordingly, the electrodes 41″, 42″ attached to the outer circumference 25″ of the wall 24″ of the fluid channel 2″ also take the same angle relative to each other, thereby constituting an angled positional relationship. Concerning the forming of a plate-like capacitor, the same is also achieved by means of an angled relative positioning of the electrodes, as known to the skilled person. In FIG. 3B, an active state of the fluid channel 2″ is shown, i.e. a fluid is flowing through the fluid channel 2″ in a direction from the rigid segment 21 to the elastic segment 22″, thereby opening up the closed end of the elastic segment 22″ and moving the electrodes 41″, 42″ away from each other. In the presently described third embodiment, due to the converging structure of the nozzle-like elastic segment 22″, the fluid can only flow in the direction from the rigid segment 21 to the elastic segment 22″, since the closed end of the elastic segment 22″ as depicted in FIG. 3B does not allow entry of fluid from the right side in the drawing, resulting in the elastic segment 22″ being arranged downstream of the rigid segment 21.
[0092] In accordance with the opening of the closed end of the elastic segment 22″, the flow 7 of the fluid within the fluid channel 2″ can be measured through change of capacitance of the electrode pair 4″ caused by the change in distance between these electrodes 41″, 42″ due to the angle-widening movement of the elastic segment 22″. This change in distance is again allowed by elastic deformation of the elastic segment 22″ caused by an increase of fluid pressure of the fluid flowing within the fluid channel 2″. In the presently described third embodiment, no further electrode pair is used, contrary to the previously described embodiments. Accordingly, in FIGS. 3A and 3B, the part of the fluid channel 2″ show in these illustrations comprises the first rigid segment 21 and the nozzle-like elastic segment 22″, wherein a transition area between those segments is again implemented without substantial interruption, and the wall 24″ of the fluid channel 2″ is substantially continuous, in particular in order to avoid any disturbances of the fluid flowing inside the fluid channel 2″.
[0093] As can be gathered from FIGS. 3A and 3B, a diameter of the fluid channel 2″ at the elastic segment 22″ in a position at which the electrodes 41″, 42′ are arranged is smaller than a diameter at the rigid segment 21. The difference in diameter can also be gathered from FIGS. 3A and 3B in the difference in distances between the respective electrodes, i.e. a distance d.sub.1st between the electrodes 31, 32 of the first pair 3 of electrodes 31, 32 provided at the rigid segment 21 at the left side is larger than a distance d″.sub.2nd between the electrodes 41″, 42″ of the second pair 4″ of electrodes 41″, 42″ provided at the elastic segment 22″ arranged on the right side of FIGS. 3A and 3B. In FIGS. 3A and 3B, the different segments 21, 22″ of the fluid channel 2″ are illustratively separated from each other by means of a linear dotted line.
[0094] In FIG. 3A, the sensor system 1″ may already comprise a fluid, such as a liquid to be measured, inside the fluid channel 2″, however with a closed end of the elastic segment 2″ at its downstream end. Thus, FIG. 3A shows an initial state of the sensor system 1″, in which there is no fluid flow within the fluid channel 2″. In FIG. 3B, on the contrary, unidirectional fluid flow 7 is present within the fluid channel 2″, which can be gathered by the enlarged distance d″.sub.2nd, which can also be referred to as d″.sub.2nd_moved, between the electrodes 41″, 42″ attached to the outer circumference 25″ of the wall 24″ of the fluid channel 2″ at the elastic segment 22″, and the opening of the downstream end of the elastic segment 22″, compared to the distance d″.sub.2nd between the electrodes 41″, 42″ in the initial state as depicted in FIG. 3A, which can also be referred to as d′.sub.2nd_unmoved. In this regard, it can be gathered from the differing distances d″.sub.2nd between the electrodes 41″, 42″ in the initial state as depicted in FIG. 3A and the enlarged state as depicted in FIG. 3B that FIG. 3A shows a state of the sensor system 1″ before expansion, and that FIG. 3B shows a state of the sensor system 1″ during fluid flow 7, i.e. after opening expansion of the elastic segment 22″.
[0095] As can also be gathered from FIGS. 3A and 3B, the surface areas A.sub.1st of the electrodes 31, 32 of the first pair 3 of electrodes 31, 32, illustrated in the drawings of FIGS. 3A and 3B in a lateral dimension of the surface area A.sub.1st, coincide with each other, in order to achieve a clear capacitor relationship between these electrodes. Further, the surface areas A″.sub.2nd of the electrodes 41″, 42″ of the second pair 4″ of electrodes 41″, 42″ coincide with each other. Thus, based on the above described equation 8, the distance d″.sub.2nd between the electrodes 41″, 42″ of the second electrode pair 4″, i.e. the moveable electrode pair in the present embodiment compared to the fixed electrode pair 3, can be calculated based on the measured capacitance of the fixed electrode pair 3. Repeating this calculation over time results in a timely progression of the distance d″.sub.2nd, which timely progression represents a change of fluid pressure of the fluid flowing within the elastic segment 22″ of the fluid channel 2″. Thus, monitoring the timely progression of the distance d″.sub.2nd corresponds to the monitoring of a timely progression of the fluid pressure of the fluid flowing within the elastic segment 22″ of the fluid channel 2″.
[0096] In FIGS. 3A and 3B, the electrodes 31, 32, 41″, 42″ of the electrode pairs 3, 4″ are depicted as plate-like components in a cross-sectional view. Here, as an example, the electrodes 31, 32, 41″, 42″ of the electrode pairs 3, 4″ can have a generally plate-like shape, which shape can follow the tubular curvature of the outer circumference 25″ of the wall 24″ of the fluid channel 2″ at least in part. Here, the overall dimensions and shapes of the opposing electrodes 31 and 32 and 41″ and 42″ correspond to each other.
[0097] Finally, FIG. 4 shows a flowchart of a method for determining the flow rate of a fluid flow within a fluid channel by means of a sensor system as described above, wherein step S1 constitutes a step of detecting a capacitance of the first pair of electrodes, such as the capacitance generated between the electrodes of the fixed electrode pair, step S2 constitutes a step of detecting a capacitance of the second pair of electrodes, such as the capacitance generated between the electrodes of the moveable electrode pair, step S3 constitutes a step of calculating a distance between the electrodes of the second pair of electrodes based on the detected capacitance of the first pair of electrodes and the capacitance of the second pair of electrodes, and step S4 constitutes a step of determining a flow rate of the fluid flow within the fluid channel based on a difference in distance between the electrodes of the second pair of electrodes over time. As an example, steps S1 and S2 can be carried-out by the sensor unit of the respective sensor system, and steps S3 and S4 can be carried-out by a processing unit of the respective sensor system. Alternatively, steps S1 and S2 can be carried out simultaneously, whereas steps S3 and S4 are carried-out subsequently. Further, any one of steps S1 and S2 can include the detection of the capacitances of several pairs of electrodes, such as, for step S1, the detection of the capacitances of several pairs of fixed electrodes provided at different rigid segments of the respective fluid channel, and, for step S2, the detection of the capacitances of several pairs of moveable electrodes provided at different elastic segments of the respective fluid channel.
[0098] In further detail, the calculation step S3 of the above-described method is based on the measured capacitance values, and the distance between the electrodes of the second pair of electrodes is then calculated as already described in detail further above. Furthermore, in regard to the method as described in view of FIG. 4, an elasticity of a respective elastic segment of the fluid channel can be adjusted based on the expected flow rate within the fluid channel beforehand, i.e. in advance before carrying out the described method, for example in the form of an optional pre-step S0. Here, the elasticity, i.e. the elastic modulus, of the elastic segment can be adjusted to the estimated or expected flow rates of the fluid within the fluid channel, and/or can be adjusted to the expected pressure changes within the fluid channel, so that a respective impact on the measured fluid can be minimized.
[0099] While the current disclosure has been described in relation to its specific embodiments, it is to be understood that this description is for illustrative purposes only. Accordingly, it is intended that the disclosure be limited only by the scope of the claims appended hereto.
