CN112833970A

CN112833970A - Flow sensor and flow monitor

Info

Publication number: CN112833970A
Application number: CN202110202300.8A
Authority: CN
Inventors: 邓锐; 范嘉俊
Original assignee: Medcaptain Medical Technology Co Ltd
Current assignee: Medcaptain Medical Technology Co Ltd
Priority date: 2021-02-23
Filing date: 2021-02-23
Publication date: 2021-05-25

Abstract

Flow sensor and flow monitor, this flow sensor includes the sleeve, first water conservancy diversion spare, the second water conservancy diversion spare, rotating member and rotational speed measurement spare, the sleeve encloses closes an air current passageway, first water conservancy diversion spare and second water conservancy diversion spare all with muffjoint and the holding of mutual interval in air current passageway, the rotating member holding is in air current passageway and is located between first water conservancy diversion spare and the second water conservancy diversion spare, it is rotatory to promote the rotating member from the gas that first water conservancy diversion spare or second water conservancy diversion spare flowed in, the rotational speed measurement spare sets up in the sleeve and is used for measuring the rotational speed of rotating member, the rotational speed of rotating member is used for converting into gaseous flow. The rotating speed of the rotating part is measured through the rotating speed measuring part, an accurate gas flow numerical value can be obtained according to the corresponding relation between the rotating speed and the flow, the flow measurement of the bidirectional airflow can be realized, the structure is simple, and the use is convenient.

Description

Flow sensor and flow monitor

Technical Field

The invention relates to the technical field of gas flow monitoring, in particular to a flow sensor and a flow monitor.

Background

The turbine type flowmeter is a velocity type flowmeter which measures the flow rate on the principle that flowing gas hits turbine blades to rotate. The rotating turbine blade forms corresponding rotating speed after being stabilized, and the flow value can be obtained by multiplying the rotating speed by the flow speed according to the relation that the rotating speed and the flow speed form a certain proportion.

The existing vortex flowmeter can only measure the flow of gas flowing in a single direction, and the flow measurement of gas flowing in two directions is difficult to realize.

Disclosure of Invention

The invention aims to provide a flow sensor and a flow monitor, which can realize the flow measurement of bidirectional airflow.

In order to realize the purpose of the invention, the invention provides the following technical scheme:

in a first aspect, the present invention provides a flow sensor, including a sleeve, a first flow guide member, a second flow guide member, a rotating member, and a rotation speed measuring member, wherein the sleeve encloses an air flow channel, the first flow guide member and the second flow guide member are both connected to the sleeve and are accommodated in the air flow channel at intervals, the rotating member is accommodated in the air flow channel and is located between the first flow guide member and the second flow guide member, the rotating member is pushed to rotate by air flowing in from the first flow guide member or the second flow guide member, the rotation speed measuring member is disposed on the sleeve and is configured to measure a rotation speed of the rotating member, and the rotation speed of the rotating member is configured to be converted into a flow rate of the air.

In one embodiment, the first flow guide and the second flow guide are used for guiding the gas flowing along the axial direction of the sleeve to flow along the radial vortex of the sleeve, and the rotating member takes the axis of the sleeve as a rotating shaft.

In one embodiment, the rotating member is rotatably connected to the first and second flow guide members.

In one embodiment, the rotating member includes a rotating portion, a first rotating shaft and a second rotating shaft, the first rotating shaft and the second rotating shaft are arranged on two opposite sides of the rotating portion, the first rotating shaft and the second rotating shaft are extended along the axis of the sleeve, the first guide member is provided with a first mounting groove, the second guide member is provided with a second mounting groove, the first rotating shaft is rotatably connected with the first mounting groove, and the second rotating shaft is rotatably connected with the second mounting groove.

In one embodiment, the first and second flow guide members are identical in structure and are installed in opposite directions, so that the gas flowing in from the first flow guide member and the gas flowing in from the second flow guide member have opposite vortex directions.

In one embodiment, the first flow guiding element includes an outer ring, a central shaft, and a plurality of blades connected between the outer ring and the central shaft, the outer ring is configured to be connected to the sleeve, the central shaft is configured to be rotatably connected to the rotating element, and the plurality of blades are arranged in an annular array centered on the central shaft.

In one embodiment, the inner wall of the sleeve is provided with a protrusion, and the first flow guide part and the second flow guide part are tightly attached to the inner wall of the sleeve and are respectively arranged on two sides of the protrusion.

In one embodiment, the rotation speed measuring unit includes an infrared emitting unit and an infrared receiving unit, the infrared emitting unit and the infrared receiving unit are disposed at two opposite sides of the rotating member in a radial direction, a connection line between the infrared emitting unit and the infrared receiving unit has a distance from a rotating shaft of the rotating member, the infrared emitting unit is configured to emit infrared rays, and the infrared receiving unit is configured to receive infrared rays.

In one embodiment, the first flow guide part and the second flow guide part are detachably connected with the sleeve, and the rotating part is detachably connected with the first flow guide part and the second flow guide part.

In a second aspect, the present invention also provides a flow monitor comprising a flow sensor according to any one of the various embodiments of the first aspect.

Through establishing the rotating member between first water conservancy diversion spare and second water conservancy diversion spare, the gas that gets into airflow channel from the sleeve both ends all can be changed flow direction by first water conservancy diversion spare or second water conservancy diversion spare earlier to promote the rotating member to rotate, the rotational speed of rethread rotational speed measuring piece measurement rotating member, and according to the corresponding relation of rotational speed and flow, can obtain accurate gas flow numerical value, can realize the flow measurement of two-way air current, simple structure, convenient to use.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a front view of an embodiment of a flow sensor;

FIG. 2 is an exploded view of an embodiment of a flow sensor;

FIG. 3 is a cross-sectional view of an embodiment of a flow sensor;

FIG. 4 is a perspective view of a first baffle of an embodiment.

Description of reference numerals:

10-sleeve, 11-airflow channel, 12-bulge;

20-a first flow guide part, 21-an outer ring, 22-a middle shaft, 23-a blade and 25-a first mounting groove;

30-a second flow guide part, 35-a second mounting groove;

40-rotating part, 41-first rotating shaft, 42-second rotating shaft, 43-rotating part;

51-infrared ray transmitting unit, 52-infrared ray receiving unit.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

Referring to fig. 1 to 4, an embodiment of the invention provides a flow sensor, which includes a sleeve 10, a first flow guide element 20, a second flow guide element 30, a rotating element 40, and a rotation speed measuring element.

The sleeve 10 is generally cylindrical and encloses a generally cylindrical gas flow passage 11. The sleeve 10 may be made of plastic, including but not limited to PC (polycarbonate), ABS (acrylonitrile-butadiene-styrene copolymer), epoxy resin, etc. The first and second

flow guide members

20 and 30 have substantially cylindrical outer peripheral surfaces, and are connected to the inner wall of the sleeve 10 and are received in the airflow passage 11 at intervals. The first and second

flow guide members

20 and 30 are generally shaped as turbines, which are not rotatable when disposed within the shroud 10, as compared to prior art turbines. The first and

second fluid guides

20 and 30 are made of plastic, including but not limited to PC (polycarbonate), ABS (acrylonitrile butadiene styrene), epoxy, etc.

The rotating member 40 is received in the airflow path 11 and located between the first flow guide member 20 and the second flow guide member 30. The rotating member 40 may be connected to any one or more of the sleeve 10, the first baffle member 20, or the second baffle member 30. The first flow guide 20 and the second flow guide 30 guide the gas, i.e., change the flow direction of the gas.

The gas flowing in from the first guide member 20 or the second guide member 30 pushes the rotation member 40 to rotate. The material of the rotating member 40 is light weight material, so that the rotating member 40 can generate the change of the rotating speed by the small change of the flow rate of the air flow.

Specifically, when the gas flows in the gas flow passage 11, there are only two directions, i.e., the first flow guide member 20 faces the first direction of the second flow guide member 30, and the second flow guide member 30 faces the second direction of the first flow guide member 20, the gas flows in the first direction and is directed by the first flow guide member 20 and then blown onto the rotary member 40, or the gas flows in the second direction and is directed by the second flow guide member 30 and then blown onto the rotary member 40; thereby pushing the rotary member 40 to rotate. The specific path of the gas flow is as follows: 1. a first direction: the air flow channel 11 entering the sleeve 10 from one end of the sleeve 10-the first flow guide 20-the rotating member 40-the second flow guide 30-is discharged from the other end of the sleeve 10; 2. a second direction: the air flow passage 11-the second flow guide 30-the rotating member 40-the first flow guide 20-entering the sleeve 10 from one end of the sleeve 10 is discharged from the other end of the sleeve 10.

The rotation speed measuring member is provided to the sleeve 10 and measures a rotation speed of the rotary member 40, and the rotation speed of the rotary member 40 is converted into a flow rate of the gas.

It can be understood that, when the rotating speed of the rotating member 40 is faster, which indicates that the flow rate of the gas is faster, the rotating speed of the rotating member 40 can be accurately measured by the rotating speed measuring member, and then the specific value of the gas flow can be obtained by multiplying the corresponding relation between the rotating speed and the flow rate by the time.

In this embodiment, the rotating member 40 is disposed between the first flow guiding member 20 and the second flow guiding member 30, the gas entering the gas flow channel 11 from the two ends of the sleeve 10 is changed in flow direction by the first flow guiding member 20 or the second flow guiding member 30 to push the rotating member 40 to rotate, the rotating speed of the rotating member 40 is measured by the rotating speed measuring member, and an accurate gas flow value can be obtained according to the corresponding relationship between the rotating speed and the flow rate, so that the flow rate of the bidirectional gas flow can be measured.

In one embodiment, referring to fig. 2 and 3, the first flow guiding element 20 and the second flow guiding element 30 are used for guiding the gas flowing along the axial direction of the sleeve 10 to flow along the radial direction of the sleeve 10 in a vortex manner, and the rotating element 40 takes the axis of the sleeve 10 as the rotating axis.

In this embodiment, the general direction of the gas flow in the gas flow channel 11 is from one end to the other. When the air flow flows in the first direction and does not meet the first flow guide 20, or when the air flow flows in the second direction and does not meet the second flow guide 30, the flow direction of the air flow is along the axial direction of the sleeve 10, specifically along the first direction or the second direction in the axial direction of the sleeve 10. When the air flow meets the first flow guide 20 in the first direction, the air flow is guided by the first flow guide 20, and when the air flow meets the second flow guide 30 in the second direction, the air flow is converted from flowing in the axial direction of the sleeve 10 to swirling in the radial direction of the sleeve 10. At this time, the overall flow direction of the air flow is still from one end to the other end of the sleeve 10, but the air flow is deflected when passing through the first flow guiding element 20 or the second flow guiding element 30, and is converted into a radial vortex from an axial direction along the sleeve 10, and at this time, the direction of the air flow has a component along the axial direction, a component along the radial direction and a component along the circumferential direction, and the air flow generates a vortex, so that the rotating element 40 between the first flow guiding element 20 and the second flow guiding element 30 can be pushed to rotate by taking the axis of the sleeve 10 as a rotating shaft.

In this embodiment, the first and second

flow guiding members

20 and 30 are arranged to guide the gas and push the rotating member 40 between the first and second

flow guiding members

20 and 30 to rotate by using the axis of the sleeve 10 as a rotating shaft, so that the gas flow can be measured in two directions and the structure is simple compared with the conventional method of measuring a rotating flow guiding member.

In one embodiment, the rotating member 40 is rotatably coupled to the first baffle member 20 and the second baffle member 30. Because the first guide part 20 and the second guide part 30 are sequentially arranged on the axial direction of the sleeve 10, and the rotating part 40 is rotatably connected with the first guide part 20 and the second guide part 30, on one hand, the first guide part 20 and the second guide part 30 can have good support for the rotating part 40, so that the rotating part 40 can stably rotate, on the other hand, the structure for supporting the rotating part 40 does not need to be additionally arranged, so that the whole structure is more compact.

In one embodiment, the rotating member 40 includes a rotating portion 43, a first rotating shaft 41 and a second rotating shaft 42, the first rotating shaft 41 and the second rotating shaft 42 are disposed on opposite sides of the rotating portion 43, and the first rotating shaft 41 and the second rotating shaft 42 both extend along the axis of the sleeve 10. The rotating portion 43 extends along the radial direction of the sleeve 10, the whole of the rotating portion 43 can be a rectangular sheet, the first rotating shaft 41 and the second rotating shaft 42 are respectively connected to the middle portions of two sides of the rotating portion 43, the first rotating shaft 41 and the second rotating shaft 42 are located in the extending direction of the same straight line, and the rotating portion 43 is symmetrically arranged relative to the first rotating shaft 41 and the second rotating shaft 42.

Alternatively, the first rotating shaft 41, the second rotating shaft 42 and the rotating part 43 may be an integrally formed integral structure.

Optionally, the first rotating shaft 41, the second rotating shaft 42, and the rotating portion 43 may also be detachable structures, for example, a rod-shaped rotating shaft penetrates through the rotating portion 43, for example, mounting holes are opened on two opposite sides of the rotating portion 43, and the first rotating shaft 41 and the second rotating shaft 42 are respectively inserted into the corresponding mounting holes to achieve connection.

Alternatively, the four corners of the rectangle of the rotating portion 43 may be set to be circular arc transition, so as to form a shape of a substantially rounded rectangle, so that the flow field is stable when the airflow passes through, and turbulence and turbulences are reduced.

The first guide member 20 is provided with a first mounting groove 25, the second guide member 30 is provided with a second mounting groove 35, the first rotating shaft 41 is rotatably connected with the first mounting groove 25, and the second rotating shaft 42 is rotatably connected with the second mounting groove 35.

Alternatively, the bottom walls of the first and second mounting

grooves

25 and 35 may be tapered, the taper angle of the taper is not limited, and the ends of the first and second

rotating shafts

41 and 42 may be tapered to facilitate the rotational connection.

In this embodiment, by providing the first mounting groove 25 and the second mounting groove 35, and rotating and connecting the first rotating shaft 41 and the first mounting groove 25, and rotating and connecting the second rotating shaft 42 and the second mounting groove 35, the installation of the rotating member 40 is realized, the structure is simple, and the operation is easy.

In one embodiment, the first and second

flow guiding members

20 and 30 are identical in structure and are installed in opposite directions, so that the gas flowing in from the first flow guiding member 20 and the gas flowing in from the second flow guiding member 30 have opposite vortex directions.

In this embodiment, the first and second fluid guides 20 and 30 have the same structure, which facilitates manufacture, and only one of them needs to be manufactured, and they are installed in opposite directions during installation, which also facilitates installation. Because the first flow guide part 20 and the second flow guide part 30 have the same structure and are installed in opposite directions, when airflow flows to the first flow guide part 20 in the first direction and flows to the second flow guide part 30 in the second direction, radial vortex can be generated, and the vortex generated in the two directions are opposite in direction, so that the rotating part 40 can be pushed to rotate.

In one embodiment, the first flow guiding element 20 includes an outer ring 21, a central shaft 22 and a plurality of blades 23 connected between the outer ring 21 and the central shaft 22, the outer ring 21 is used for connecting with the sleeve 10, the central shaft 22 is used for rotatably connecting with the rotating element 40, and the plurality of blades 23 are arranged in an annular array with the central shaft 22 as the center.

In this embodiment, outer lane 21 is the annular of annular end to end connection, outer lane 21 is connected with sleeve 10, in order to fix first water conservancy diversion spare 20 to sleeve 10, the one end and the outer lane 21 of a plurality of blades 23 are connected, the other end is connected with axis 22, make a plurality of blades 23 stable in structure, the axis of axis 22 and the axis collineation of sleeve 10, the effect of blade 23 is the direction, the annular array's of a plurality of blades 23 arranges, can lead the whole of gas in the airflow channel 11 of sleeve 10, the quantity of blade 23 does not do the restriction, as 3, 4, 5, 6, 8 all can.

The mode of rotationally connecting the middle shaft 22 and the rotating member 40 may be as in the foregoing embodiments, a first mounting groove 25 is formed on the middle shaft 22, and the first rotating shaft 41 of the rotating member 40 is rotationally connected with the first mounting groove 25; the middle shaft 22 may also protrude, a groove is formed on the rotating member 40, and the middle shaft 22 is rotatably connected with the groove. The middle shaft 22 may be made of a material with high hardness and wear resistance, such as metal and precious stone (e.g., sapphire), and the middle shaft can stably support the rotating member 40 and has high wear resistance, thereby prolonging the service life.

In one embodiment, the inner wall of the sleeve 10 is provided with a protrusion 12, and the first flow guiding member 20 and the second flow guiding member 30 are tightly attached to the inner wall of the sleeve 10 and are respectively disposed on two sides of the protrusion 12.

In this embodiment, the first flow guiding element 20 and the second flow guiding element 30 may be in interference fit with the sleeve 10, and may be stably fixed without any other mounting structure. The protrusion 12 is provided to space the first flow guiding member 20 and the second flow guiding member 30, and to position the first flow guiding member 20 and the second flow guiding member 30 with the protrusion 12, that is, to push the first flow guiding member 20 and the second flow guiding member 30 into the sleeve 10 from both ends of the sleeve 10 until the first flow guiding member 20 and the second flow guiding member 30 contact with both sides of the protrusion 12, respectively. The bulge 12 can be of an annular structure and is arranged on the inner wall of the sleeve 10 in a circle; the protrusions 12 may be a plurality of protrusions, and are circumferentially spaced on the inner wall of the sleeve 10. The projection 12 may be of unitary construction with the sleeve 10.

Optionally, the first flow guiding element 20 and the second flow guiding element 30 are detachably connected to the sleeve 10, for example, in the manner of interference fit, or in the manner of other mounting structures, for example, a snap ring is clamped on a side of the first flow guiding element 20 facing away from the protrusion 12, and a snap ring is clamped on a side of the second flow guiding element 30 facing away from the protrusion 12.

Optionally, the rotating member 40 is detachably connected to the first flow guide member 20 and the second flow guide member 30. When the first flow guide part 20 and the sleeve 10 are installed, the rotating part 40 and the first flow guide part 20 are installed, if necessary, some tools can be used for limiting the rotating part 40 in a matching mode, the second flow guide part 30 and the sleeve 10 are installed and fixed, and meanwhile, the second flow guide part 30 and the rotating part 40 are installed.

The detachable connection mode is convenient for the independent manufacture of each part and is very easy to install.

In one embodiment, the first baffle 20 and the sleeve 10 can be made as a unitary structure, which reduces the number of steps required to install the first baffle 20 into the sleeve 10.

In one embodiment, the rotation speed measuring device includes an infrared emitting unit 51 and an infrared receiving unit 52, the infrared emitting unit 51 and the infrared receiving unit 52 are oppositely disposed at two sides of the rotating member 40 in a radial direction, a connection line between the infrared emitting unit 51 and the infrared receiving unit 52 has a distance from a rotating shaft of the rotating member 40, the infrared emitting unit 51 is used for emitting infrared rays, and the infrared receiving unit 52 is used for receiving infrared rays.

In this embodiment, the infrared emitting unit 51 emits infrared rays, the infrared receiving unit 52 receives infrared rays, and in the process of rotating the rotating member 40, the infrared rays emitted by the infrared emitting unit 51 rotate for one turn at the rotating member 40 and pass through twice, so that the infrared receiving unit 52 can receive infrared rays at two time points, and the infrared receiving unit cannot receive infrared rays due to shielding of the rotating member 40 in the rest time, and the rotating speed of the rotating member 40 can be obtained by measuring the time interval of receiving infrared rays by the infrared receiving unit 52, and further the flow rate of the airflow can be calculated. It is understood that the material of the rotating member 40 should not transmit infrared rays in order to block infrared rays. The distance between the connecting line of the infrared transmitting unit 51 and the infrared receiving unit 52 and the rotating shaft of the rotating member 40 is set as required, and the purpose is that in the process of transmitting and receiving infrared rays, infrared rays are not shielded by the rotating shaft of the rotating member 40 but only shielded by the blades of the rotating member 40, so that some time infrared rays can be received, and the situation that the time infrared rays cannot be received all the time due to shielding by the rotating shaft is avoided.

The conventional method for measuring the flow rate of the gas by using the turbine blade 23 as a rotating method needs a complicated measuring structure to measure the rotating speed of the turbine blade 23, occupies a large space, and cannot be used in a small-sized device. Compared with the existing measuring mode, the rotating speed of the rotating part 40 is obtained by measuring the time interval at which the infrared rays are received through the matching of the infrared ray transmitting unit 51 and the infrared ray receiving unit 52, and then the flow rate of the air flow is obtained.

The embodiment of the invention also provides a flow rate monitor which comprises the flow rate sensor in any one of the embodiments. Specifically, this flow monitor can be hand-held type lung function appearance, breathing machine, oxygenerator etc. wherein, flow sensor's sleeve 10's one end can link to each other with the patient, and the other end links to each other with flow detector, and when the patient exhales or breathes in, can monitor the gaseous or inhaled flow of patient's exhalation, and then can be according to whether this flow is in the standard value that accords with normal people, judge whether normal is breathed to the patient to and whether carry out relevant treatment etc..

While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A flow sensor is characterized by comprising a sleeve, a first flow guide piece, a second flow guide piece, a rotating piece and a rotating speed measuring piece, wherein the sleeve encloses an air flow channel, the first flow guide piece and the second flow guide piece are both connected with the sleeve and are contained in the air flow channel at intervals, the rotating piece is contained in the air flow channel and is positioned between the first flow guide piece and the second flow guide piece, air flowing in from the first flow guide piece or the second flow guide piece pushes the rotating piece to rotate, the rotating speed measuring piece is arranged on the sleeve and is used for measuring the rotating speed of the rotating piece, and the rotating speed of the rotating piece is used for being converted into the flow of the air.

2. The flow sensor of claim 1, wherein the first flow guide and the second flow guide are each configured to guide gas flowing in an axial direction of the sleeve to swirl flow in a radial direction of the sleeve, and the rotating member has an axis of rotation of the sleeve.

3. The flow sensor of claim 2, wherein the rotating member is rotationally coupled to the first baffle member and the second baffle member.

4. The flow sensor according to claim 3, wherein the rotating member includes a rotating portion, a first rotating shaft and a second rotating shaft, the first rotating shaft and the second rotating shaft are disposed on opposite sides of the rotating portion, the first rotating shaft and the second rotating shaft both extend along an axis of the sleeve, the first flow guiding member is provided with a first mounting groove, the second flow guiding member is provided with a second mounting groove, the first rotating shaft is rotatably connected with the first mounting groove, and the second rotating shaft is rotatably connected with the second mounting groove.

5. The flow sensor of claim 2, wherein the first and second flow guide members are constructed identically and are mounted in opposite directions such that the gas flowing from the first flow guide member and the gas flowing from the second flow guide member have opposite swirling directions.

6. The flow sensor of claim 5, wherein the first flow directing element includes an outer ring, a central shaft, and a plurality of blades coupled between the outer ring and the central shaft, the outer ring configured to couple to the sleeve, the central shaft configured to rotatably couple to the rotating element, the plurality of blades arranged in an annular array centered on the central shaft.

7. The flow sensor according to claim 1, wherein the inner wall of the sleeve is provided with a protrusion, and the first flow guide member and the second flow guide member are closely attached to the inner wall of the sleeve and are respectively disposed on two sides of the protrusion.

8. The flow sensor according to claim 1, wherein the rotation speed measuring member includes an infrared ray emitting unit and an infrared ray receiving unit, the infrared ray emitting unit and the infrared ray receiving unit are oppositely disposed at both sides of the rotation member in a radial direction, and a connection line of the infrared ray emitting unit and the infrared ray receiving unit has a spaced distance from a rotation axis of the rotation member, the infrared ray emitting unit is configured to emit infrared rays, and the infrared ray receiving unit is configured to receive infrared rays.

9. The flow sensor of claim 1, wherein the first flow guide member and the second flow guide member are removably coupled to the sleeve, or wherein the first flow guide member is integrally formed with the sleeve and the second flow guide member is removably coupled to the sleeve; the rotating piece is detachably connected with the first flow guide piece and the second flow guide piece.

10. A flow monitor comprising a flow sensor according to any one of claims 1 to 9.