Flow sensor

Abstract

The flow sensor comprises a first fan blade, an inductance coil and a conversion circuit, the inductance coil comprises a wire coil, the end faces of the two axial ends of the wire coil are a first side face and a second side face correspondingly, the first side face is constructed into a spiral coil, the wire coil is arranged on the radial side of the first fan blade, and the second side face is constructed into a spiral coil; the first side face corresponds to the first fan blades at intervals, and the first fan blades are used for rotating relative to the wire coil under the driving of fluid, so that the first fan blades and the wire coil dynamically and alternately get close to and get away from each other, and the inductance value of the inductance coil is changed; the conversion circuit is electrically connected with the inductance coil and is configured to convert the change of the inductance value of the inductance coil into a circuit frequency. According to the flow sensor, the principle that the inductance value of the inductance coil is changed due to the fact that the first blade (the magnetic core part) gets close to or away from the inductance coil is utilized for flow detection, a conversion circuit can be simplified, and the circuit design cost can be reduced.

Description

Technical Field

[0001] The present application relates to the technical field of flow sensors, and in particular to a flow sensor. Background Art

[0002] A flow sensor is proposed in the related technology. The rotor is designed as a conductive metal sheet so that during rotation, the alternating magnetic field generated by the inductor coil is cut to generate eddy currents. The eddy currents will generate mutual inductance between the magnetic field and the alternating magnetic field generated by the inductor coil. The rotation speed of the rotor can be determined by the periodic frequency of the mutual inductance between the rotor and the magnetic field, thereby realizing flow detection.

[0003] In this technical solution, since the inductor coil is required to generate an alternating magnetic field, an excitation circuit needs to be designed to provide an alternating current to the resonant circuit (i.e., the inductor coil) so that the inductor coil can generate an alternating magnetic field after the alternating current is passed through it. That is, the circuit part needs to be equipped with an excitation circuit to complete the detection, which increases the complexity and cost of the circuit design. Utility Model Content

[0004] One purpose of the present application is to propose a flow sensor that detects flow by utilizing the principle that the inductance of the inductor changes when the first blade (magnetic core) approaches or moves away from the inductor, thereby simplifying the circuit and reducing the circuit design cost.

[0005] In order to solve the above technical problems, this application adopts the following technical solutions:

[0006] The technical solution of the first aspect of the present application proposes a flow sensor, comprising:

[0007] A first blade, wherein the first blade has two or more first blades arranged at intervals in the circumferential direction, and at least a portion of each of the first blades is configured as a magnetic core portion;

[0008] An inductor coil, wherein the inductor coil comprises a wire drum, and the end surfaces at both axial ends of the wire drum are respectively a first side surface and a second side surface, the first side surface is configured as a spiral coil, the wire drum is arranged on a radial side of the first blade, the first side surface corresponds to the first blade interval, and the first blade is used to rotate relative to the wire drum under the drive of the fluid, so that the first blade and the wire drum are dynamically alternately approached and separated, so that the inductance of the inductor coil changes;

[0009] The conversion circuit is electrically connected to the inductor coil and is configured to convert the change of the inductance of the inductor coil into a circuit frequency and output it, and the circuit frequency corresponds to the rotation speed of the first fan blade.

[0010] According to some technical solutions of the present application, the conversion circuit includes an oscillation circuit, a frequency-voltage conversion circuit and a signal processing module; the oscillation circuit is electrically connected to the inductor, the oscillation circuit is also connected to the frequency-voltage conversion circuit, and the frequency-voltage conversion circuit is connected to the signal processing module;

[0011] The oscillation circuit is configured to output an oscillation frequency, wherein the oscillation frequency varies with the inductance of the inductor;

[0012] The frequency-to-voltage conversion circuit is configured to identify the oscillation frequency, and convert the oscillation frequency into a voltage signal and output the voltage signal;

[0013] The signal processing module is configured to process the voltage signal to output the circuit frequency.

[0014] According to some technical solutions of the present application, the oscillation frequency is negatively correlated with the inductance of the inductor coil.

[0015] According to some technical solutions of the present application, the frequency-to-voltage conversion circuit is configured as follows:

[0016] When it is identified that the oscillation frequency is greater than a frequency threshold, outputting a first voltage signal;

[0017] When it is identified that the oscillation frequency is less than or equal to the frequency threshold, a second voltage signal is output.

[0018] According to some technical solutions of the present application, the oscillation circuit includes an LC three-point sinusoidal wave oscillation circuit.

[0019] According to some technical solutions of the present application, the oscillation circuit includes a triode, a first resistor, a second resistor, a first capacitor, a second capacitor, a third capacitor and a fourth capacitor;

[0020] The first end of the first resistor is used to connect to the first end of the inductor, the second end of the first resistor is connected to the base of the transistor, and the second end of the first resistor is also connected to the first end of the first capacitor;

[0021] The second end of the first capacitor is connected to the first end of the second resistor, the first end of the third capacitor, and the first end of the fourth capacitor. The second end of the second resistor is connected to the emitter of the transistor and the second end of the third capacitor. The second end of the third capacitor is also connected to the first end of the second capacitor. The second end of the second capacitor is connected to the collector of the transistor. The second end of the second capacitor is also used to be connected to the first end of the inductor. The second end of the fourth capacitor is used to be connected to the second end of the inductor. The second end of the inductor is also connected to a power supply voltage.

[0022] According to some technical solutions of the present application, the frequency-to-voltage conversion circuit includes a first chip and a fifth capacitor;

[0023] The first pin of the first chip is grounded, the second pin of the first chip is connected between the second capacitor and the third capacitor, the third pin of the first chip is connected to the fifth pin of the first chip, the fourth pin of the first chip is connected between the second end of the inductor and the power supply voltage, the fourth pin of the first chip is also connected to the first output port, the fifth pin of the first chip is connected to the second output port, the fifth pin of the first chip is also connected to the first end of the fifth capacitor, the second end of the fifth capacitor is connected to the first end of the fourth capacitor, the second end of the fifth capacitor is also grounded, and the second end of the fifth capacitor is also connected to the third output port.

[0024] According to some technical solutions of the present application, the magnetic core is made of a soft magnetic non-metallic material.

[0025] According to some technical solutions of the present application, the inductance of the inductor coil increases and decreases in response to the approach and distance between the first blade and the wire drum; during the rotation of the first fan blade relative to the wire drum, the maximum inductance L1 of the inductor coil and the minimum inductance L2 of the inductor coil satisfy: 0.5%≤(L1-L2) / L1≤10%.

[0026] According to some technical solutions of the present application, the flow sensor further includes:

[0027] A shell having a side wall surrounding a fluid channel, the first fan blade is rotatably arranged in the fluid channel, the first fan blade is used to rotate relative to the shell under the drive of the fluid in the fluid channel, the wire drum is arranged on the outside of the side wall, the first side surface is opposite to the outer surface of the side wall, and the wire drum and the first fan blade are separated by the side wall.

[0028] In the flow sensor of the present application, at least a portion of the first blade is configured as a magnetic core, and the wire drum of the inductance coil is located on the radial side of the first blade, the end face of the wire drum at one axial end is the first side face, and the end face of the wire drum at the other axial end is the second side face, the first side face is constructed as a spiral coil, and the first side face of the wire drum corresponds to the interval of the first blade. By setting the first side face of the wire drum to include a spiral coil, when the first blade of the first blade approaches the wire drum, the wire drum can sense the magnetic core of the first blade with higher sensitivity to form an inductance change, and accordingly, when the first blade rotates relative to the wire drum under the drive of the fluid, so that the first blade and the wire drum dynamically alternately approach and move away from each other, the inductance coil can more sensitively mutual inductance with the magnetic core of the first blade through the wire drum, thereby presenting a more accurate corresponding change in inductance. The conversion circuit is electrically connected to the inductor coil, so that the change in inductance can be further converted into a circuit frequency and output through the conversion circuit, wherein the circuit frequency corresponds to the rotation speed of the first fan blade, so that the rotation speed of the first fan blade can be sensitively identified according to the circuit frequency, and then the fluid flow rate can be accurately identified through the rotation speed of the first fan blade, thereby achieving the purpose of fluid flow detection. Compared with the solution that requires the provision of an excitation circuit to provide an alternating current to the inductor coil to generate an alternating magnetic field, the present application uses the principle that the inductance of the inductor coil changes when the first blade (magnetic core) approaches or moves away from the inductor coil to detect the flow rate. It does not require the inductor coil to generate an alternating magnetic field, so there is no need to design an excitation circuit, which can simplify the circuit and reduce the circuit design cost.

[0029] It should be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above and other objects, features and advantages of the present application will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings.

[0031] Figure 1 It is a schematic diagram of the exploded structure of the flow sensor of Example 1 of the present application.

[0032] Figure 2 It is a schematic diagram of the partial cross-sectional structure of the flow sensor of the first embodiment of the present application.

[0033] Figure 3 yes Figure 2 An enlarged structural schematic diagram of part A is shown in FIG.

[0034] Figure 4 It is a side structural schematic diagram of the flow sensor of Example 1 of the present application.

[0035] Figure 5 yes Figure 4 The cross-sectional structure diagram of the BB portion is shown in FIG.

[0036] Figure 6 It is a schematic diagram of the partial cross-sectional structure of the flow sensor of the first embodiment of the present application.

[0037] Figure 7 It is a structural schematic diagram of the first fan blade in the first embodiment of the present application when it is in the first position relative to the wire drum.

[0038] Figure 8 yes Figure 7 A schematic diagram of the side structure of the first fan blade and the wire drum is shown in FIG.

[0039] Fig. 9 It is a structural schematic diagram of the first fan blade in the first embodiment of the present application when it is in the second position relative to the wire coil.

[0040] Fig.10 It is a schematic structural diagram of the conversion circuit in Example 1 of the present application.

[0041] Fig.11 It is a circuit diagram of the conversion circuit in Example 1 of the present application.

[0042] The reference numerals are as follows:

[0043] 1. first fan blade; 11. first blade; 111. first inclined surface; 112. second inclined surface; 12. first central portion; 13. shaft body;

[0044] 2. Inductor coil; 21. Wire reel; 22. Wire;

[0045] 3. first housing; 31. side wall; 311. groove; 3111. bottom wall; 32. stop step; 33. fence; 34. first liquid inlet; 35. second liquid outlet;

[0046] 4. guide member; 41. guide vane; 42. center portion of the guide member; 43. connecting groove; 44. ring body;

[0047] 5. rotor cover; 51. notch;

[0048] 6. bracket; 61. shaft hole;

[0049] 7. Outer cover;

[0050] 8. Circuit board; 81. Connecting terminal; 82. Conversion circuit; 821. Oscillation circuit; 822. Frequency identification circuit; 823. Signal processing module. DETAILED DESCRIPTION

[0051] Although the present application can be easily embodied in different forms of embodiments, only some of the specific embodiments are shown in the drawings and described in detail in this specification. It should be understood that this description should be regarded as an exemplary illustration of the principles of the present application and is not intended to limit the present application to that described herein.

[0052] Thus, a feature indicated in this specification will be used to illustrate one of the features of an embodiment of the present application, rather than implying that each embodiment of the present application must have the described feature. In addition, it should be noted that this specification describes many features. Although some features can be combined together to illustrate possible system designs, these features can also be used in other combinations that are not explicitly described. Thus, unless otherwise stated, the described combinations are not intended to be limiting.

[0053] In the embodiments shown in the drawings, the directions used to explain the structure and movement of various elements of the present application are not absolute but relative. These descriptions are appropriate when these elements are in the positions shown in the drawings. If the description of the positions of these elements changes, the directions also change accordingly.

[0054] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these example embodiments are provided so that the description of the present application will be more comprehensive and complete and the concepts of the example embodiments will be fully conveyed to those skilled in the art. The accompanying drawings are only schematic illustrations of the present application and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted.

[0055] Embodiment 1

[0056] See also Figure 1 , Embodiment 1 of the present application provides a flow sensor for detecting the flow rate of a fluid.

[0057] For example, the flow sensor includes a first fan blade 1, an inductor 2, a first shell 3, a flow guide 4, a rotor cover 5, a bracket 6, an outer cover 7, a circuit board 8 and the like.

[0058] The first fan blade 1 may also be referred to as a rotor in the art. The first fan blade 1 has two or more first blades 11 circumferentially spaced apart. At least a portion of each first blade 11 is configured as a magnetic core portion, and the magnetic core portion is made of soft magnetic material.

[0059] The inductor 2 includes a wire drum 21 , wherein an end surface of one axial end of the wire drum 21 is a first side surface, and an end surface of the other axial end of the wire drum 21 is a second side surface, and the first side surface is configured as a spiral coil.

[0060] Optionally, the wire drum 21 of the electromagnetic coil may be configured to have a certain axial thickness, and the axial direction of the wire drum 21 may be the thickness direction of the wire drum 21 .

[0061] Optionally, the first side surface may be configured as a planar spiral coil. For example, the end surface of one axial end of the wire coil 21 may be configured as a planar spiral coil, or the wire coil 21 may be configured as a planar spiral coil as a whole.

[0062] For example, the wire drum 21 is a structure formed by winding a conductive wire (such as a flat wire or a round conductive wire, etc.), and the end face of one axial end thereof is a planar spiral coil. For example, the wire drum 21 as a whole is a single-layer planar spiral coil, or the wire drum 21 as a whole is a multi-layer planar spiral coil arranged in an axially overlapping manner, and each layer of the planar spiral coil is a planar structure formed by spirally winding a conductive wire from the center to the outside (or spirally winding from the outer circle to the inside). Alternatively, the wire drum 21 as a whole is a shape formed by multiple cylindrical coils nested inwardly (or outwardly) in sequence, and the ends of the multiple cylindrical coils are roughly located in the same plane, thereby constructing the characteristic that the end face of one axial end of the wire drum 21 is a planar spiral coil.

[0063] It is understandable that in the art, a planar spiral coil may also be referred to as a planar spiral coil or a planar spiral coil or a flat inductor. It should be noted that the plane in the planar spiral, or the flat in the planar spiral coil / flat inductor, does not specifically mean that the surface of each layer of the planar spiral coil is an absolute plane, but should be openly understood that each layer of the planar spiral coil of the present application can be set to a shape of a plane surface or a curved surface with a certain curvature (such as a concave surface or a convex surface) according to requirements, or can appropriately accommodate a reasonable deviation of each layer of the planar spiral coil being manufactured into a curved surface with a slight curvature (such as a concave surface or a convex surface).

[0064] Of course, the present application is not limited thereto, and in other embodiments, the first side surface may be configured as a spiral coil with a slightly concave shape, or the first side surface may be configured as a spiral coil with a slightly convex shape.

[0065] By using the wire drum 21 including the spiral coil, when the first blade approaches the wire drum 21, the wire drum 21 can more sensitively sense the magnetic core of the first blade. In this way, as the first blade 11 approaches or moves away from the wire drum 21, the wire drum 21 will respond more sensitively to the change in inductance, so that the frequency of the inductance change of the wire drum 21 more realistically and sensitively reflects the rotation speed of the first blade 1, so as to more accurately express the flow rate of the fluid.

[0066] The wire drum 21 is arranged on one radial side of the first blade 1, and the two sides of the wire drum 21 along the axial direction correspond to form a first side surface and a second side surface, and the first side surface of the wire drum 21 corresponds to the first blade 1 at intervals, and accordingly, the second side surface of the wire drum 21 is arranged to face away from the first blade 1. The first blade 1 is used to rotate relative to the wire drum 21 under the drive of the fluid, so that the first blade 11 and the wire drum 21 dynamically and alternately approach and move away. Among them, by the first blade 11 and the wire drum 21 dynamically and alternately approaching and moving away, the magnetic core of the first blade 11 and the wire drum 21 dynamically and alternately approach and move away. It can be understood that when the first blade 11 and the wire drum 21 are relatively close to each other, the wire drum 21 responds to the approach of the magnetic core and generates a relatively large inductance. When the first blade 11 and the wire drum 21 are relatively far away from each other, the wire drum 21 responds to the distance of the magnetic core and generates a relatively small inductance or no inductance. In this way, the first blade 11 and the wire drum 21 are dynamically and alternately approached and moved away from each other, so that the inductance of the wire drum 21 of the inductor coil 2 is induced to change alternately between large and small, so as to utilize the change in the size of the inductance to reflect the rotation speed of the first fan blade 1, and then reflect the flow rate of the fluid used to drive the first fan blade 1 to rotate, thereby achieving the purpose of flow detection.

[0067] Among them, since at least a part of the first blade 11 is set as a magnetic core part, the magnetic core part is a soft magnetic material, the end face of the axial end of the wire drum 21 of the inductor 2 includes a spiral coil, and the wire drum 21 is located on the radial side of the first fan blade 1 and corresponds to the first fan blade 1 at an interval. By using the spiral coil to sense the approach and distance of the magnetic core part of the soft magnetic material, when the first blade 11 of the first fan blade 1 approaches the wire drum 21, the wire drum 21 can sense the magnetic core part of the first blade 11 with higher sensitivity to form an inductance change. Correspondingly, when the first fan blade 1 rotates relative to the wire drum 21 under the drive of the fluid, the magnetic core part of the first blade 11 and the wire drum 21 dynamically and alternately approach and move away from each other. In this way, the wire drum 21 will more sensitively form an alternating change of large and small inductance in response to the approach and distance of the first blade 11, so that the rotation speed of the first fan blade 1 can be more sensitively identified through the frequency of the change of the inductance, and then the fluid flow rate can be more accurately identified through the rotation speed of the first fan blade 1, so as to achieve the purpose of more accurate and higher sensitivity flow detection. And because the magnetic core is made of soft magnetic material, there is no magnetic field around the soft magnetic material. In this way, while realizing the mutual inductance between the magnetic core and the wire drum 21 to achieve the aforementioned flow detection purpose, it also avoids the problem of the first fan blade 1 absorbing iron filings in the fluid, greatly reducing the risk of the first fan blade 1 getting stuck, and better ensuring the reliability of the long-term use of the product. And compared with the solution using Hall elements, this flow sensor reduces the cost of the product by eliminating the Hall element, and can also avoid the high failure rate caused by the high damage rate of the Hall element, which is more conducive to the promotion of the product.

[0068] When the first side surface of the wire drum 21 is a planar spiral coil, the wire drum 21 has a higher sensitivity to the approach and separation of the magnetic core of the first blade.

[0069] The soft magnetic material can further be selected as a soft magnetic poor conductor material, such as a soft magnetic non-conductive material or a soft magnetic non-metallic material (such as a ceramic material, etc.) or a soft magnetic high resistivity alloy material (such as an iron-aluminum alloy, an iron-silicon alloy, an iron-silicon-aluminum alloy, etc.). The soft magnetic material itself has excellent magnetic permeability, so it can affect the inductance of the wire drum by approaching or moving away from the wire drum, such as increasing the inductance of the wire drum by approaching the wire drum, and reducing the inductance of the wire drum by moving away from the wire drum. The soft magnetic poor conductor material has excellent magnetic permeability and a high resistivity, which can further prevent the magnetic core from generating eddy current losses under the influence of the magnetic field of the wire drum.

[0070] For example, the magnetic core is a soft ferrite (also known as a non-metallic ferrimagnetic soft magnetic material). It can be understood that there is no magnetic field around the soft magnetic material, so it will not absorb iron filings in the fluid. The ferrite can be a "functional ceramic material" sintered by mixing iron oxide with other metal oxides. It has good magnetic conductivity and has advantages such as small residual magnetism after the external current is removed compared with general metals. For example, the soft ferrite can be specifically manganese-zinc ferrite, nickel-zinc ferrite, barium-zinc ferrite, magnesium-zinc ferrite, etc. Of course, in other embodiments, the magnetic core can be other soft magnetic materials other than soft ferrite, such as nanomaterials containing FeCoNiCrAL alloy and / or NiZnCuFe oxide, ceramic materials, amorphous soft magnetic alloys, etc.

[0071] Optionally, combined Figure 1 and Figure 7 It can be understood that the first fan blade 1 specifically includes a first central portion 12 and more than two first blades 11, and each first blade 11 is radially extended outward from the edge of the first central portion 12. The first central portion 12 and the more than two first blades 11 are optionally arranged as an integrated structure, and all are made of soft magnetic material, that is, the first fan blade 1 as a whole is a magnetic core portion of soft magnetic material. In this way, the first central portion 12 and the more than two first blades 11 are integrally formed, the processing is more efficient, the first blades 11 are not easy to break or loose, the product reliability is better, and each first blade 11 itself is a magnetic core portion as a whole. In this way, it is easier to ensure that among the multiple first blades 11 of the first fan blade 1, the minimum spacing between the magnetic core portion of each first blade 11 and the wire drum 21 is roughly uniform. Therefore, when each first blade 11 is at the minimum spacing with the wire drum 21, the inductance amplitude on the wire drum 21 fluctuates little, and the identification of the inductance frequency can be more accurate.

[0072] Optionally, combined Figure 1 and Figure 7 It can be understood that each first blade 11 of the first blade 1 is radially distributed outward relative to the center of the first blade 1, that is, each first blade 11 extends outward in a straight line in the radial direction; and the root of each first blade 11 is arranged parallel to the axial direction of the first blade 1, that is, the intersection position of each first blade 11 and the first center portion 12 is arranged in a straight line that is roughly parallel to the axial direction of the first blade 1. With this shape of the first blade 1, the first blade 1 rotates relative to the wire drum 21, so that a clearer correspondence is formed between the first blade 11 and the wire drum 21 (such as Figure 7 shown) and misalignment (as shown) Fig. 9 The state of the first blade 11 and the wire drum 21 is switched by the attached Figure 7 The corresponding state shown switches to Fig. 9 In the misaligned state shown, the transition angle in which a part of the first blade 11 corresponds to the wire drum 21 and another part of the first blade 11 is misaligned with the wire drum 21 is smaller. Correspondingly, the duration of the intermediate transition state in which a part of the first blade 11 corresponds to the wire drum 21 and another part of the first blade 11 is misaligned with the wire drum 21 is shorter, so that the alternating changes in the size of the inductance on the wire drum 21 are more distinct, so as to more accurately identify the frequency of change of the inductance, thereby improving the detection accuracy of the fluid flow. Of course, the present application is not limited to this. In other embodiments, the first blade 11 can be arranged with a certain curvature along the circumferential direction, and / or the root of the first blade 11 (that is, the intersection of the first blade 11 and the first center portion 12) can be arranged with a certain helicity along the axial direction of the first center portion 12.

[0073] Alternatively, if Figure 1As shown, the first fan blade 1 also includes a shaft 13, which is connected to the first center portion 12 and protrudes axially on both sides relative to the first center portion 12. The shaft 13 is used for the rotational connection of the first fan blade 1. Further optionally, the shaft 13 and the first center portion 12 are two components of different materials. For example, the shaft 13 can be a plastic shaft, and an axial hole that penetrates axially is arranged inside the first center portion 12. The shaft 13 is inserted and connected in the axial hole of the first center portion 12. The use of a plastic shaft for the rotational connection of the first fan blade 1 can help reduce the rotational friction of the first fan blade 1, thereby further improving the accuracy of the product in detecting fluid flow. Further optionally, the shaft body 13 can be set to a two-section structure, such as the shaft body 13 is divided into a first shaft section and a second shaft section, and a shaft shoulder baffle is provided on the first shaft section and the second shaft section, wherein one end of the first shaft section is rotatably connected, such as one end of the first shaft section is inserted into the connecting groove 43 of the guide member 4, and one end of the second shaft section is rotatably connected, such as one end of the second shaft section is inserted into the shaft hole 61 of the bracket 6, and the other end of the first shaft section and the other end of the second shaft section are correspondingly inserted into the shaft hole of the first center part 12 from both ends of the shaft hole of the first center part 12, wherein the shaft hole of the first center part 12 is set to a polygonal hole, and accordingly, the part where the first shaft section is inserted into the first center part 12 and the part where the second shaft section is inserted into the first center part 12 are both set to a polygonal surface contour, so that the first shaft section and the second shaft section both rotate with the first fan blade 1. One of the first shaft section and the second shaft section is provided with a boss at one end close to each other, and the other is provided with a groove, so that the boss is inserted into the groove, so that the first shaft section and the second shaft section are plug-fitted at one end close to each other. The first fan blade 1 is located between the shoulder baffle of the first shaft section and the shoulder baffle of the second shaft section, thereby realizing the axial limitation of the axial ends of the first fan blade 1. Of course, the present application is not limited to this. In other embodiments, the shaft body 13 can also be made of soft magnetic material and made into one piece with the first center portion 12, or, in other embodiments, the shaft body 13 can also be made of a metal shaft.

[0074] Optionally, the wire drum 21 is made of self-adhesive enameled wire. It can be understood that the surface of the self-adhesive enameled wire has an adhesive layer, which melts when exposed to high temperature, which can facilitate the bonding of two adjacent turns of the wire drum 21 and the bonding and fixation of the wire drum 21 as a whole, making the fixation and processing of the wire drum 21 more convenient.

[0075] Alternatively, if Figure 1 As shown, the surface of the wire drum 21 is configured to be a rectangle with a certain length and width. Of course, the present application is not limited thereto, and in other embodiments, the surface of the wire drum 21 can be configured to be an ellipse, a circle, etc.

[0076] Optionally, there is a through hole in the center of the wire drum 21, and the wire of the wire drum 21 is spirally wound around the circumference of the through hole, and the wall thickness direction of the wire drum 21 is consistent with the penetration direction of the through hole. In this way, a larger surface area of ​​the wire drum 21 can be achieved using the same length of wire to further improve the detection accuracy of the fluid flow. Of course, the present application is not limited to this. In other embodiments, the center of the wire drum 21 may not be provided with a through hole, so that the wire drum 21 is a solid structure as a whole.

[0077] It can be understood that the inductance of the inductor 2 increases in response to the first blade 11 and the wire drum 21 approaching each other, and the inductance of the inductor 2 decreases in response to the first blade 11 and the wire drum 21 moving away from each other. Optionally, the flow sensor is configured such that during the rotation of the first blade 1 relative to the wire drum 21, the maximum inductance L1 of the inductor 2 and the minimum inductance L2 of the inductor 2 satisfy: 0.5% ≤ (L1-L2) / L1 ≤ 10%. In this way, the frequency of the inductance change of the wire drum 21 can be further accurately identified, thereby making the flow detection accuracy of the flow sensor higher.

[0078] Further optionally, the ratio of the absolute value of the difference between L1 and L2 to L1 is greater than or equal to 1% and less than or equal to 10%. While more accurately and sensitively identifying the frequency of inductance variation of the wire reel 21 is achieved, the area size of the wire reel 21 can be better taken into account.

[0079] Optionally, the range of the distance value between the first side and one of the first blades 11 when the distance is closest is: less than or equal to 5mm, greater than or equal to 0.5mm. Setting the distance value between the first side and one of the first blades 11 when the distance is closest to less than or equal to 5mm allows the magnetic core of the first blade 11 to be more sensitive to the mutual inductance with the wire drum 21 when it is closest to the wire drum 21, thereby more significantly increasing the inductance on the wire drum 21. In this way, the change amplitude of the inductance on the wire drum 21 is larger, and the identification of the change frequency of the inductance on the wire drum 21 is more accurate, thereby achieving more accurate measurement of the flow value. Setting the distance value between the first side and one of the first blades 11 when the distance is closest to greater than or equal to 0.5mm makes it easier to configure the spacing between the first blade 11 and the wire drum 21, while ensuring the smoothness of the rotation of the first fan blade 1 and reducing the cost of the product.

[0080] Optionally, the rotation of the first blade 1 relative to the wire drum 21 includes a first position and a second position; Figure 7 and Figure 8 As shown, when the first fan blade 1 rotates to the first position, the minimum distance is formed between the wire drum 21 and one of the first blades 11. At this time, since the distance between the magnetic core of the first blade 11 and the wire drum 21 is the smallest, the inductance on the wire drum 21 is the largest; Fig. 9As shown, when the first fan blade 1 rotates to the second position, the wire drum 21 corresponds to the angle position between two adjacent first blades 11. At this time, there is no first blade 11 on the first fan blade 1 directly facing the wire drum 21, and the inductance on the wire drum 21 is the smallest. As the first fan blade 1 rotates clockwise or counterclockwise relative to the wire drum 21, the first fan blade 1 alternately switches between the first position and the second position, so that the inductance on the wire drum 21 fluctuates periodically, thereby forming a frequency expression of the inductance change on the wire drum 21. The rotation speed of the first fan blade 1 can be detected through the frequency of the change of the inductance, thereby identifying the flow rate of the fluid.

[0081] For example, Fig. 9 As shown, the wire drum 21 has a first direction Y perpendicular to the axial configuration of the first blade 1, wherein the maximum distance W4 between the magnetic cores of the circumferentially adjacent first blades 11 is greater than the width value W3 of the wire drum 21 along the first direction Y. In this way, the wire drum 21 can reliably form a state in which the angle between the wire drum 21 and the adjacent first blade 11 of the first blade 1 corresponds to each other without the first blade 11 facing the wire drum 21, that is, the second position of the rotation of the first blade 1 can be more reliably formed, so that a smaller minimum inductance is formed on the wire drum 21, so that the difference between the maximum inductance and the minimum inductance on the wire drum 21 is larger, so that the inductance change frequency of the wire drum 21 can be more accurately identified.

[0082] Alternatively, if Figure 8 As shown, the wire drum 21 has a second direction X parallel to the axial configuration of the first blade 1, wherein the width value W2 of the wire drum 21 along the second direction X is greater than or equal to the axial length W1 of the first blade 1. In this way, the wire drum 21 can cover the first blade 11 to the greatest extent, so that when the first blade 11 corresponds to the wire drum 21 (for example, when the first blade 1 is in the first position), a larger maximum inductance can be formed on the wire drum 21, so that the difference between the maximum inductance and the minimum inductance on the wire drum 21 is larger, so that the inductance change frequency of the wire drum 21 can be more accurately identified.

[0083] Optionally, the width value W2 of the wire drum 21 along the second direction X is greater than the width value W3 of the wire drum 21 along the first direction Y. When the first fan blade 1 reaches the first position, the first blade 11 corresponds to the wire drum 21. Since the width value W2 of the wire drum 21 along the second direction X is designed to be larger, correspondingly, the area directly facing the first blade 11 and the wire drum 21 is also correspondingly larger, so that the value of the maximum inductance on the wire drum 21 is correspondingly larger, so as to form a clearer inductance change frequency and improve the detection accuracy. Since the width value W3 of the wire drum 21 along the first direction Y is designed to be smaller, correspondingly, a smaller first blade 11 spacing W4 can be used to ensure that the wire drum 21 falls accurately into the second position. In this way, more first blades 11 can be set on the first fan blade 1, so that more samples of inductance frequency changes can be obtained when the first fan blade 1 rotates one circle, so that the detection accuracy of the fluid flow is also higher. In combination with the foregoing, by setting the width value W2 of the wire drum 21 along the second direction X to be greater than the width value W3 of the wire drum 21 along the first direction Y, the detection accuracy of the inductance change frequency and the sample size of the inductance frequency change corresponding to one rotation of the first fan blade 1 can be improved simultaneously, thereby improving the flow detection reliability and detection accuracy of the product.

[0084] Of course, the present application is not limited to this. In fact, the width of the wire drum 21 along the first direction and the width along the second direction can have a variety of configuration relationships, and is not limited to the case where W2 is greater than W3. In other embodiments, W2 can also be designed to be less than W3, or W2 can be designed to be equal to W3.

[0085] Optionally, the first fan blade 1 may be Figure 1 and Figure 7 As shown, four first blades 11 are arranged uniformly and spaced apart along the circumference of the first central portion 12 to form a cross shape, and a 90-degree angle is formed between any adjacent first blades 11. Of course, the present application is not limited thereto, and in other embodiments, the four first blades 11 are arranged non-uniformly and spaced apart along the circumference of the first central portion 12, for example, in a cross shape, so that the four first blades 11 form two opposite angles greater than 90 degrees and two opposite angles less than 90 degrees.

[0086] Optionally, the first side of the cable drum 21 is configured to be concavely curved and spaced to correspond to the first blade 1, and the second side is configured to be convexly curved and facing away from the first blade 1. Figure 7 and Fig. 9As shown, by setting the wire drum 21 into an arc shape, under the condition of the same length and width, the wire drum 21 has a larger surface area, and at the same time, when the first blade 11 is close to the wire drum 21, the radially adjacent coils of the wire drum 21 are closer to the first blade 11, so as to sense the magnetic core of the first blade 11 with higher sensitivity, and the response accuracy and sensitivity of the inductance of the wire drum 21 to the distance from the magnetic core of the first blade 11 can be further improved, thereby improving the accuracy and sensitivity of flow detection. Of course, the present application is not limited to this, and in other embodiments, the wire drum can also be planar.

[0087] Optionally, combined Figure 1 , Figure 2 , Figure 3 It can be understood that the first shell 3 has a side wall 31, and the side wall 31 is arranged along the circumferential direction to enclose a fluid channel that passes through both ends of the axial direction. The first fan blade 1 is rotatably arranged in the fluid channel, and the first fan blade 1 is used to rotate relative to the first shell 3 under the drive of the fluid in the fluid channel. The wire drum 21 is arranged on the outside of the side wall 31, and the surface of one side of the wire drum 21 is opposite to the outer surface of the side wall 31. The wire drum 21 is separated from the first fan blade 1 by the side wall 31. In this way, the wire drum 21 will not contact the fluid in the fluid channel, which can better achieve water vapor isolation and reduce the risk of product failure.

[0088] Optionally, the outer surface of the side wall 31 is set to a convex arc surface corresponding to the position of the wire drum 21, and the wire drum 21 is in a concave arc shape as a whole, so that the first side surface is roughly a concave arc surface, and the curvature of the first side surface is roughly consistent with the curvature of the convex arc surface at the position of the side wall 31 corresponding to the wire drum 21, and the second side surface is roughly a convex arc surface, and the first side surface of the wire drum 21 faces the side where the first fan blade 1 is located, and is attached to the convex arc surface of the side wall 31. That is, it is equivalent to placing a thin-walled curved wire drum 21 against the arc surface of the side wall 31, and the arc-shaped wire drum 21 is set corresponding to the first fan blade 1 through the first side surface set in a concave arc shape. Under the conditions of the same length and width dimensions, the wire drum 21 has a larger surface area, which can further improve the response accuracy and sensitivity of the inductance of the wire drum 21 to the distance from the magnetic core of the first blade 11.

[0089] Optionally, combined Figure 2 and Figure 3 It can be understood that the portion of the side wall 31 corresponding to the wire drum 21 is set as a groove 311, and the wire drum 21 is accommodated in the groove 311. The groove 311 is protruded in the direction away from the wire drum 21 relative to the side wall 31 around the groove 311. The groove 311 is located on the radial side of the first blade 1 and forms a gap with the first blade 1. The wire drum 21 is set in the groove 311, and the structure of the groove 311 protruding into the fluid channel can make the wire drum 21 closer to the first blade 1 in the flow channel, thereby reducing the minimum distance between the first blade 11 and the wire drum 21. That is, relatively speaking, Figure 5 As shown, when the first fan blade 1 reaches the first position, the distance between the first blade 11 and the wire drum 21 is h1, and the normal distance between the first blade 11 at the end of the first fan blade 1 facing away from the wire drum 21 and the outer surface of the side wall 31 of the first shell 3 is h2. By setting the groove 311 to protrude toward the fluid channel relative to the inner surface of the side wall 31, the value of h1 is made smaller than h2. Compared with the case where the distance between the first blade 11 and the wire drum 21 is h2, the wire drum 21 can more sensitively sense the approach of the first blade 11 to increase the inductance, thereby correspondingly improving the accuracy of flow detection. In addition, the structure in which the wire drum 21 is accommodated in the groove 311 can also be beneficial to the installation and positioning of the wire drum 21, which can better ensure the accuracy of the assembly alignment of the wire drum 21 and the first fan blade 1, thereby improving the consistency of product quality.

[0090] Optionally, combined Figure 4 , Figure 5 and Figure 6 It can be understood that the bottom wall 3111 of the groove 311 separates the wire drum 21 from the first blade 1, wherein the wall thickness of the bottom wall 3111 of the groove 311 is less than the wall thickness of the side wall 31 around the groove 311. In this way, the minimum distance between the first blade 1 and the first blade 11 can be further reduced, so that the wire drum 21 can more sensitively sense the approach of the first blade 11 to increase the inductance, thereby correspondingly improving the accuracy of flow detection.

[0091] Alternatively, if Figure 3 As shown, the guide member 4 is fixed in the fluid channel, and the guide member 4 is arranged on one axial side of the first blade 1. The guide member 4 is used to guide the fluid, so that the fluid guided by the guide member 4 can drive the first blade 1 to rotate. In this way, the driving efficiency of the fluid on the first blade 1 can be improved, thereby improving the detection accuracy of the fluid flow.

[0092] Optionally, combined Figure 1 , Figure 2 and Figure 3 It can be understood that the first housing 3 is provided with a first liquid inlet 34 and a first liquid outlet 35 connected with the fluid channel, the first liquid inlet 34 and the first liquid outlet 35 are arranged on both sides of the axial direction of the first fan blade 1, and the guide member 4 is arranged between the first liquid inlet 34 and the first fan blade 1. When the liquid enters the first housing 3 from the first liquid inlet 34 and flows along the axial direction of the first housing 3, the guide member 4 is used to guide the fluid, which can ensure that the fluid drives the first fan blade 1 to rotate more efficiently.

[0093] Optionally, combined Figure 3 and Figure 8It can be understood that in the first fan blade 1, each first blade 11 is respectively provided with a first inclined surface 111 at one end axially close to the guide member 4. In this way, the fluid flowing axially toward the first blade 11 can be guided to the side of the first blade 11 by the first inclined surface 111, thereby reducing the impact and jamming between the fluid and the first blade 11, making the fluid flow smoother, which is beneficial to reducing the resistance loss of the fluid and enabling the fluid to more efficiently drive the first fan blade 1 to rotate, thereby improving the flow measurement accuracy.

[0094] Of course, the present application is not limited to this. In other embodiments, only a portion of the first blades 11 of the first fan blade 1 may be provided with the first inclined surface 111 , while the remaining first blades 11 may not be provided with the first inclined surface 111 .

[0095] Optionally, combined Figure 3 and Figure 8 It can be understood that in the first fan blade 1, the end of each first blade 11 axially away from the guide member 4 is respectively provided with a second inclined surface 112. In this way, the fluid leaving the first blade 11 along the axial direction can be guided by the second inclined surface 112 and leave the first blade 11 more quickly, making the fluid flow smoother, which is beneficial to reducing the resistance loss of the fluid and also reduces the rotational resistance of the first blade 11, thereby improving the flow measurement accuracy.

[0096] Of course, the present application is not limited to this. In other embodiments, only a portion of the first blades 11 of the first fan blade 1 may be provided with the second inclined surface 112 , while the remaining first blades 11 may not be provided with the second inclined surface 112 .

[0097] To give a further example, the guide member 4 includes a guide member center portion 42 and a plurality of guide blades 41 arranged at intervals in the circumferential direction of the guide member center portion 42. The guide blades 41 have a certain spiral curvature in the axial direction, so that the fluid moving axially in the fluid channel has a circumferential component velocity after passing through the guide blades 41. In this way, the fluid with a circumferential component velocity will drive the first fan blade 1 to rotate when flowing through the first blade 11.

[0098] Optionally, the guide blade 41 also has a certain spiral curvature along the circumferential direction, which can further enhance the guiding effect on the fluid.

[0099] Alternatively, if Figure 3 As shown, the guide member 4 also includes a ring body 44, and a plurality of guide blades 41 and a guide member center portion 42 are nested in the ring body 44. One end of the guide blade 41 is connected to the guide member center portion 42, and the other end of the guide blade 41 is connected to the ring body 44. In this way, the strength and stability of the guide blade 41 can be improved, and the guide blade 41 is not easy to shake under the impact of the fluid, thereby reducing the flow resistance generated by the guide blade 41 and improving the accuracy of flow detection.

[0100] Optionally, the guide member 4 can be configured as an integrally injection-molded plastic component, so that the guide member 4 has low cost and can further reduce product cost. Of course, in other embodiments, the guide member 4 can also be made of other materials besides plastic.

[0101] Optionally, the rotor cover 5 is connected to the fluid channel, and a bracket 6 is provided in one axial end of the rotor cover 5, and an axial hole 61 is provided on the bracket 6. The guide member 4 is connected to the end of the rotor cover 5 away from the bracket 6, and the first fan blade 1 is located in the rotor cover 5 and between the guide member 4 and the bracket 6. A connecting groove 43 is provided on the guide member center portion 42 of the guide member 4, and an axial end of the shaft body 13 of the first fan blade 1 extends into the connecting groove 43 and can rotate in the connecting groove 43, and the other axial end of the shaft body 13 is passed through the axial hole 61 on the bracket 6 and can rotate in the axial hole 61. In this way, the first fan blade 1, the guide member 4 and the bracket 6 are positioned and assembled with the rotor cover 5 as a carrier, which can facilitate the positioning between the first fan blade 1 and the guide member 4, and avoid the problems of the first fan blade 1 and the guide member 4 being installed incorrectly or reversely.

[0102] Further optionally, the rotor cover 5 can be configured as follows Figure 1 The rotor cover 5 is a cylindrical body with two axial ends passing through it as shown in the figure. A notch 51 passing through it axially is provided on one radial side of the rotor cover 5. The rotor cover 5 is accommodated in the fluid channel, and the groove 311 extends into the notch 51. In this way, the rotation of the rotor cover 5 in the fluid channel can be limited by the cooperation between the groove 311 and the notch 51. A stop step 32 is provided on the inner surface of the side wall 31. The groove 311 is axially extended away from the stop step 32. One end of the rotor cover 5 provided with a bracket 6 abuts against the stop step 32, and the flow guide 4 axially abuts against the end of the groove 311 away from the stop step 32. One end of the rotor cover 5 provided with a bracket 6 abuts against the stop step 32 axially, and one end of the rotor cover 5 provided with a flow guide 4 abuts against the groove 311 axially through the flow guide 4, thereby limiting the axial movement of the rotor cover 5 in the fluid channel. In this way, the fixed connection of the rotor cover 5 in the fluid channel is achieved.

[0103] Through this structural design, when assembling the flow sensor, the notch 51 of the rotor cover 5 can be aligned with the groove 311, and the rotor cover 5 can be pushed into the first housing 3 from the end where the bracket 6 is set, until the end of the rotor cover 5 where the bracket 6 is set axially abuts against the stop step 32, and then the first blade 1 is installed into the rotor cover 5, so that the shaft 13 of the first blade 1 is embedded in the shaft hole 61 of the bracket 6, and then the guide 4 is connected to the end of the rotor cover 5 away from the bracket 6, and the guide 4 is axially abutted against the groove 311 to axially lock the rotor cover 5. It has the advantage of convenient assembly.

[0104] Optionally, the connection between the guide member 4 and the rotor cover 5 can be in the form of a snap connection, such as a snap button is provided on the ring body 44 of the guide member 4 to snap with the rotor cover 5, so as to further improve the convenience of assembly. Of course, in other embodiments, the guide member 4 and the rotor cover 5 can also be connected by connecting members such as screws.

[0105] Optionally, the rotor cover 5 and the bracket 6 can be integrally formed, for example, the rotor cover 5 and the bracket 6 can be integrally injection molded. In this way, the connection reliability between the bracket 6 and the rotor cover 5 is higher, so that the first fan blade 1 can be supported more reliably and stably, and the assembly steps of the rotor cover 5 and the bracket 6 are saved, thereby saving the assembly time of the product.

[0106] Alternatively, if Figure 3 As shown, the outer cover 7 is located outside the side wall 31, and the outer cover 7 is connected to the side wall 31 to enclose a storage space, and the wire drum 21 is located in the storage space; the circuit board 8 is located in the storage space, and the circuit board 8 is located on the side of the wire drum 21 facing away from the first fan blade 1, and the inductor 2 also includes a wire 22 extending from the wire drum 21, and the wire 22 is connected to the circuit board 8. In this way, the circuit board 8 and the wire drum 21 are packaged, which can further prevent the circuit board 8 and the wire drum 21 from contacting water vapor, prolong the life of the product, and also make the product suitable for high temperature and high humidity environments such as water heaters.

[0107] Further optionally, if Figure 3 As shown, a fence portion 33 protruding relative to the outer surface of the side wall 31 is provided on the side wall 31, and the fence portion 33 is distributed around the groove portion 311, so that the groove portion 311 and the fence portion 33 together define a storage space similar to a step groove, the wire drum 21 is located in the groove portion 311, the circuit board 8 is located in the area surrounded by the fence portion 33, and is supported on the transition step between the groove portion 311 and the fence portion 33, and the outer cover 7 is installed on the side of the circuit board 8 facing away from the wire drum 21, so as to encapsulate the circuit board 8 and the wire drum 21 in the storage space. In this way, the circuit board 8 can further limit the position of the wire drum 21, and also make the assembly of the product more compact, thereby saving the volume of the product.

[0108] Alternatively, if Figure 5 As shown, the flow sensor further includes a connecting terminal 81 , one end of which extends into the accommodation space to be connected to the circuit board 8 , and the other end of the connecting terminal 81 extends out of the accommodation space to be used for external connection of the circuit board 8 .

[0109] Alternatively, if Fig.10As shown, a conversion circuit 82 is disposed on the circuit board 8, and the conversion circuit 82 is connected to the inductor 2 (i.e., the wire reel 21) through a wire. The conversion circuit 82 can identify the change in the inductance of the inductor 2, and convert the change in the inductance of the inductor 2 into a circuit frequency and output it, wherein the circuit frequency output by the conversion circuit 82 corresponds to the rotation speed of the first fan blade 1, such as the circuit frequency output by the conversion circuit 82 and the rotation speed of the first fan blade 1 may be positively correlated, and the circuit frequency output by the conversion circuit 82 and the rotation speed of the first fan blade 1 may also be in a positive proportional relationship.

[0110] Alternatively, if Fig.10 As shown, the conversion circuit 82 includes an oscillating circuit 821, a frequency-voltage conversion circuit 822, and a signal processing module 823. The oscillating circuit 821 is electrically connected to the inductor 2 (i.e., the coil 21), and the oscillating circuit 821 is also connected to the frequency-voltage conversion circuit 822, and the frequency-voltage conversion circuit 822 is connected to the signal processing module 823.

[0111] The oscillation circuit 821 can generate an oscillating current, and the oscillation frequency output by the oscillation circuit 821 can change with the change of the inductance of the inductor coil 2. Specifically, the oscillation circuit 821 may include an LC three-point sinusoidal wave oscillation circuit, which includes an amplifier and a positive feedback loop. The amplifier may be a unipolar transistor or a field effect tube, and the positive feedback loop is composed of an inductor and a capacitor. The principle is to use the positive feedback loop to maintain oscillation. When the circuit starts working, the power supply charges the capacitor through a resistor, so that the voltage across the capacitor gradually increases. When the voltage across the capacitor reaches a certain value, the transistor starts to turn on, and the current flows from the power supply through the transistor and the load, and the capacitor starts to discharge. When the voltage across the capacitor drops to a certain value, the transistor is turned off, the current stops flowing, and the capacitor is recharged. This process is repeated continuously to form a stable oscillation signal. The LC three-point sinusoidal wave oscillation circuit may include a capacitor three-point oscillation circuit and an inductor three-point circuit, which has the characteristics of high stability, good output waveform, adjustable frequency and low power. The oscillation circuit 821 may also include an LC oscillation circuit and an RC oscillation circuit. According to the frequency calculation formula of the oscillation circuit 821, the oscillation frequency output by the oscillation circuit 821 is negatively correlated with the inductance of the inductor 2. That is, as the inductance of the inductor 2 increases, the oscillation frequency output by the oscillation circuit 821 decreases. And as the inductance of the inductor 2 decreases, the oscillation frequency output by the oscillation circuit 821 increases. Among them, the frequency calculation formula of the oscillation circuit 821 is as follows:

[0112] Wherein, f represents the oscillation frequency output by the oscillation circuit 821, L represents the inductance of the inductor 2, and C represents the capacitance of the capacitor.

[0113] The frequency-voltage conversion circuit 822 can identify the oscillation frequency output by the oscillation circuit 821, and convert the oscillation frequency into a voltage signal and output it. Specifically, the frequency-voltage conversion circuit 822 can output a first voltage signal when it is identified that the oscillation frequency is greater than a frequency threshold. The first voltage signal can be a high-level signal or a low-level signal. The frequency-voltage conversion circuit 822 can output a second voltage signal when it is identified that the oscillation frequency is less than or equal to the frequency threshold. The second voltage signal can also be a high-level signal or a low-level signal. The first voltage signal and the second voltage signal are two identical voltage signals, such as when the first voltage signal is a high-level signal, the second voltage signal can be a low-level signal. When the first voltage signal is a low-level signal, the second voltage signal can be a high-level signal.

[0114] The frequency-to-voltage conversion circuit 822 includes a chip, which includes an acquisition module, a comparison module and an output module, wherein the acquisition module is used to acquire the oscillation frequency output by the oscillation circuit 821. The comparison module is used to compare the acquired oscillation frequency output by the oscillation circuit 821 with the frequency threshold. The output module is used to output a first voltage signal when the oscillation frequency is greater than the frequency threshold, and output a second voltage signal when the oscillation frequency is less than or equal to the frequency threshold.

[0115] The signal processing module 823 can process the voltage signal (such as the first voltage signal and the second voltage signal) output by the frequency-to-voltage conversion circuit 822 into a square wave waveform to obtain the circuit frequency and output it.

[0116] The conversion circuit 82 provided in the embodiment of the present application can convert the change in the inductance of the inductor 2 identified into a circuit frequency and output it. The circuit frequency is positively correlated with the rotation speed of the first fan blade 1, so the rotation speed of the first fan blade 1 can be determined according to the circuit frequency, and then the fluid flow rate can be accurately identified by the rotation speed of the first fan blade 1, thereby achieving the purpose of fluid flow detection.

[0117] When the first fan blade 1 rotates driven by the fluid, so that the first blade 11 approaches-moves away-approaches the wire drum 21, the wire drum 21 will generate a high-low-high inductance signal and output it to the oscillation circuit 821. The oscillation circuit 821 converts the inductance signal into a frequency signal and outputs it to the frequency identification circuit 822. The frequency identification circuit 822 is provided with a frequency threshold. When the frequency signal is higher than the set frequency threshold, the frequency identification circuit 822 outputs a high or low level. When the frequency signal is lower than the set frequency threshold, the frequency identification circuit 822 outputs a low or high level. The signal processing module 823 forms a square wave waveform from the high or low level from the frequency identification circuit 822, and identifies and processes the square wave waveform to determine the rotation speed of the first fan blade 1, and then identifies the fluid flow rate through the rotation speed of the first fan blade 1.

[0118] Specifically, the calculation formula of the inductance of the inductor coil is as follows:

[0119] L=μN 2 A / λ, where L represents the inductance of the inductor, μ represents the magnetic permeability, N represents the number of coil turns, A represents the winding area, and λ represents the winding length. It can be seen that the inductance L of the inductor is positively correlated with the magnetic permeability μ. When the first fan blade 1 rotates under the drive of the fluid, so that the first blade 11 (magnetic core) approaches the wire drum 21, the magnetic conductive medium changes from air to the first blade 11 (magnetic core). Since the magnetic permeability of air is less than that of the first blade 11 (magnetic core), the magnetic permeability μ increases, and the inductance L of the inductor increases. When the first fan blade 1 rotates under the drive of the fluid, so that the first blade 11 (magnetic core) moves away from the wire drum 21, the magnetic conductive medium changes from the first blade 11 (magnetic core) to air, which causes the magnetic permeability μ to decrease, and the inductance L of the inductor decreases. That is, when the first blade 1 rotates under the drive of the fluid, so that the first blade 11 (magnetic core) is close to the wire drum 21, the wire drum 21 generates a high inductance signal. When the first blade 1 rotates under the drive of the fluid, so that the first blade 11 (magnetic core) is far away from the wire drum 21, the wire drum 21 generates a low inductance signal.

[0120] Alternatively, if Fig.11 As shown, the oscillation circuit 821 includes a transistor Q1, a first resistor R1, a second resistor R2, a first capacitor C1, a second capacitor C2, a third capacitor C3 and a fourth capacitor C4. Among them, the first end of the first resistor R1 is used to connect the first end of the inductor L1, the second end of the first resistor R1 is connected to the base of the transistor Q1, and the second end of the first resistor R1 is also connected to the first end of the first capacitor C1. The second end of the first capacitor C1 is connected to the first end of the second resistor R2, the first end of the third capacitor C3, and the first end of the fourth capacitor C4, the second end of the second resistor R2 is connected to the emitter of the transistor Q1 and the second end of the third capacitor C3, the second end of the third capacitor C3 is also connected to the first end of the second capacitor C2, the second end of the second capacitor C2 is connected to the collector of the transistor Q1, the second end of the second capacitor C2 is also used to connect to the first end of the inductor L1, the second end of the fourth capacitor C4 is used to connect to the second end of the inductor L1, and the second end of the inductor L1 is also connected to the power supply voltage VCC.

[0121] It should be noted that Fig.11The inductor L1 shown in is the inductor 2 or the wire drum 21 mentioned above in the embodiment of the present application. In the oscillation circuit 821, the first resistor R1, the first capacitor C1 and the inductor L1 form an RLC circuit. When the first capacitor C1 is charged to a certain voltage, it starts to discharge, and generates a reverse electromotive force through the induction of the inductor L1, causing the first capacitor C1 to continue to discharge. When the voltage of the first capacitor drops to a certain level, the inductor L1 starts to charge again and generates a forward electromotive force, thereby causing the first capacitor C1 to start charging. This charging and discharging process is repeated continuously, forming an oscillation of the circuit. The inductor L1 plays a role in maintaining oscillation in the oscillation circuit 823. Changes in the inductor L1 can correspondingly change the oscillation frequency and waveform in the oscillation circuit 821. When the inductance of the inductor L1 increases, the oscillation frequency of the circuit will also decrease; on the contrary, when the inductance of the inductor L1 decreases, the oscillation frequency of the circuit will increase. Therefore, when the first fan blade 1 rotates under the drive of the fluid, so that the first blade 11 is close to the inductor L1, the inductance of the inductor L1 will increase, and accordingly, the oscillation frequency of the oscillation circuit 821 will decrease. When the first fan blade 1 rotates under the drive of the fluid, so that the first blade 11 is away from the inductor L1, the inductance of the inductor L1 will decrease, and accordingly, the oscillation frequency of the oscillation circuit 821 will increase.

[0122] Alternatively, if Fig.11 As shown, the frequency-to-voltage conversion circuit 822 includes a first chip U1 and a fifth capacitor C5. Among them, the first pin 1 of the first chip U1 is grounded GND, the second pin 2 of the first chip U1 is connected between the second capacitor C2 and the third capacitor C3, the third pin 3 of the first chip U1 is connected to the fifth pin 5 of the first chip U1, the fourth pin 4 of the first chip U1 is connected between the second end of the inductor L1 and the power supply voltage VCC, the fourth pin 4 of the first chip U1 is also connected to the first output port 1, the fifth pin 5 of the first chip U1 is connected to the second output port 2, the fifth pin 5 of the first chip U1 is also connected to the first end of the fifth capacitor C5, the second end of the fifth capacitor C5 is connected to the first end of the fourth capacitor C4, the second end of the fifth capacitor C5 is also grounded GND, and the second end of the fifth capacitor C5 is also connected to the third output port 3.

[0123] It should be noted that the second pin 2 of the first chip U1 is connected between the second capacitor C2 and the third capacitor C3, so that the oscillation frequency generated by the oscillation circuit 821 can be obtained through the second pin 2. Then the frequency is judged by the first chip U1. If the oscillation frequency of the oscillation circuit is greater than the frequency threshold, a high level can be output to the first output port through the fourth pin 4 (which is connected to the power supply voltage VCC); if the oscillation frequency of the oscillation circuit is not greater than the frequency threshold, a low level can be output to the second output port through the fifth pin 5 (which is grounded after passing through the fifth capacitor C5). Alternatively, the frequency is judged by the first chip U1. If the oscillation frequency of the oscillation circuit is greater than the frequency threshold, a low level can be output to the second output port through the fifth pin 5 (which is grounded after passing through the fifth capacitor C5); if the oscillation frequency of the oscillation circuit is not greater than the frequency threshold, a high level can be output to the first output port through the fourth pin 4 (which is connected to the power supply voltage VCC). Thus, the frequency-to-voltage conversion circuit 822 can realize the conversion of the change of the oscillation frequency of the oscillation circuit 821 into a change of the voltage signal.

[0124] The signal processing module 823 is connected to the frequency-voltage conversion circuit 822, so that a square wave waveform can be formed based on the changing voltage signal, and a frequency is obtained and output based on the square wave waveform. The signal processing module 823 can be a waveform generator. The frequency output by the signal processing module 823 is positively correlated with the rotation speed of the first fan blade 1, so that the rotation speed of the first fan blade 1 can be calculated based on the output frequency, and the fluid flow rate can be further calculated.

[0125] The flow sensor provided in the first embodiment has the advantages of low cost, small size and low failure rate. The flow sensor detects the flow rate by using the principle that the inductance of the inductor changes when the first blade (magnetic core) approaches or moves away from the inductor. Since the inductance signal of the inductor changes significantly, accurate signal conversion can be achieved through a simple conversion circuit, which can simplify the circuit and reduce the circuit design cost.

[0126] The water heater of the present application has all the above beneficial effects by being provided with the flow sensor described in any of the above embodiments, which will not be described in detail here.

[0127] Although the present application has been described with reference to several typical embodiments, it should be understood that the terms used are illustrative and exemplary, rather than restrictive. Since the present application can be implemented in a variety of forms without departing from the spirit or essence of the invention, it should be understood that the above embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope defined by the appended claims, so all changes and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. A flow sensor, characterized in that: include: A first blade, wherein the first blade has two or more first blades arranged at intervals in the circumferential direction, and at least a portion of each of the first blades is configured as a magnetic core portion; An inductor coil, wherein the inductor coil comprises a wire drum, and the end surfaces at both axial ends of the wire drum are respectively a first side surface and a second side surface, the first side surface is configured as a spiral coil, the wire drum is arranged on a radial side of the first blade, the first side surface corresponds to the first blade interval, and the first blade is used to rotate relative to the wire drum under the drive of the fluid, so that the first blade and the wire drum are dynamically alternately approached and separated, so that the inductance of the inductor coil changes; The conversion circuit is electrically connected to the inductor coil and is configured to convert the change of the inductance of the inductor coil into a circuit frequency and output it, wherein the circuit frequency corresponds to the rotation speed of the first fan blade.

2. The flow sensor according to claim 1, characterized in that: The conversion circuit includes an oscillation circuit, a frequency-voltage conversion circuit and a signal processing module; the oscillation circuit is electrically connected to the inductor, the oscillation circuit is also connected to the frequency-voltage conversion circuit, and the frequency-voltage conversion circuit is connected to the signal processing module; The oscillation circuit is configured to output an oscillation frequency, wherein the oscillation frequency varies with the inductance of the inductor; The frequency-to-voltage conversion circuit is configured to identify the oscillation frequency, and convert the oscillation frequency into a voltage signal and output the voltage signal; The signal processing module is configured to process the voltage signal to output the circuit frequency.

3. The flow sensor according to claim 2, characterized in that: The oscillation frequency is negatively correlated with the inductance of the inductor.

4. The flow sensor according to claim 2, characterized in that: The frequency-to-voltage conversion circuit is configured as follows: When it is identified that the oscillation frequency is greater than a frequency threshold, outputting a first voltage signal; When it is identified that the oscillation frequency is less than or equal to the frequency threshold, a second voltage signal is output.

5. The flow sensor according to claim 2, characterized in that: The oscillation circuit comprises an LC three-point sinusoidal wave oscillation circuit.

6. The flow sensor according to claim 2, characterized in that: The oscillation circuit comprises a triode, a first resistor, a second resistor, a first capacitor, a second capacitor, a third capacitor and a fourth capacitor; The first end of the first resistor is used to connect to the first end of the inductor, the second end of the first resistor is connected to the base of the transistor, and the second end of the first resistor is also connected to the first end of the first capacitor; The second end of the first capacitor is connected to the first end of the second resistor, the first end of the third capacitor, and the first end of the fourth capacitor. The second end of the second resistor is connected to the emitter of the transistor and the second end of the third capacitor. The second end of the third capacitor is also connected to the first end of the second capacitor. The second end of the second capacitor is connected to the collector of the transistor. The second end of the second capacitor is also used to be connected to the first end of the inductor. The second end of the fourth capacitor is used to be connected to the second end of the inductor. The second end of the inductor is also connected to a power supply voltage.

7. The flow sensor according to claim 6, characterized in that: The frequency-to-voltage conversion circuit includes a first chip and a fifth capacitor; The first pin of the first chip is grounded, the second pin of the first chip is connected between the second capacitor and the third capacitor, the third pin of the first chip is connected to the fifth pin of the first chip, the fourth pin of the first chip is connected between the second end of the inductor and the power supply voltage, the fourth pin of the first chip is also connected to the first output port, the fifth pin of the first chip is connected to the second output port, the fifth pin of the first chip is also connected to the first end of the fifth capacitor, the second end of the fifth capacitor is connected to the first end of the fourth capacitor, the second end of the fifth capacitor is also grounded, and the second end of the fifth capacitor is also connected to the third output port.

8. The flow sensor according to claim 1, characterized in that: The magnetic core is made of a soft magnetic non-metal material.

9. The flow sensor according to claim 1, characterized in that: The inductance of the inductor coil increases or decreases in response to the first blade and the wire drum approaching or moving away from each other; During the rotation of the first fan blade relative to the wire drum, the maximum inductance L1 of the inductor coil and the minimum inductance L2 of the inductor coil satisfy: 0.5%≤(L1-L2) / L1≤10%.

10. The flow sensor according to any one of claims 1 to 9, characterized in that: The flow sensor also includes: A shell having a side wall surrounding a fluid channel, the first fan blade is rotatably arranged in the fluid channel, the first fan blade is used to rotate relative to the shell under the drive of the fluid in the fluid channel, the wire drum is arranged on the outside of the side wall, the first side surface is opposite to the outer surface of the side wall, and the wire drum and the first fan blade are separated by the side wall.

Images