Direct-reading water meter dial and reading detection method thereof and water meter

Abstract

This application relates to the field of digital conversion of water meters, and discloses a direct-reading water meter digit wheel, its reading detection method, and the water meter itself. The direct-reading water meter digit wheel includes a coaxially mounted digit wheel stator and digit wheel rotor. An excitation coil is located inside the outer ring of the stator, and multiple three-terminal tapped induction coil segments are located outside the inner ring. The rotor has a high-permeability magnetic core. The excitation coil generates an alternating magnetic field, and the iron core moves with the rotor, modulating the local magnetic field through magnetic permeability, causing a differential electromotive force to be generated between the two half-coil segments of the induction coil. This application utilizes the differential signal detection principle, achieving full sealing and waterproofing without a light-transmitting channel, and effectively offsetting temperature drift and electromagnetic common-mode interference. It solves the problem that traditional direct-reading water meters struggle to balance compact structure, high waterproofing, and reading stability, and is suitable for use in series with multiple digit wheels in confined spaces.

Description

Technical Field

[0001] This application relates to the field of water meter measurement technology, and in particular to a direct-reading technology that converts the digits of a mechanical water meter into digital values. Background Technology

[0002] Currently, the digitization technologies for water meter digits mainly include photoelectric direct reading and inductive direct reading. However, existing technical solutions still have certain limitations in practical applications.

[0003] Photoelectric direct reading methods typically require a reserved optical signal transmission channel in the digit wheel structure, which places high demands on the internal light environment of the water meter. In humid environments such as underground wells, condensation, water mist, or contaminants can easily obstruct the signal, leading to incorrect signal interpretation. At the same time, the requirement for light transmittance makes it difficult to achieve a completely sealed physical structure for the digit wheel assembly, limiting the improvement of its waterproof performance.

[0004] Traditional inductive direct-reading methods, while not requiring a light-transmitting channel, typically rely on measuring changes in the absolute value of inductance. Since parameters such as coil resistance and core permeability are highly sensitive to temperature, changes in ambient temperature can cause measurement drift, affecting the accuracy and stability of the readings. Furthermore, some inductive solutions require complex core structures within limited character wheel space, making it difficult to balance structural compactness with signal detection sensitivity.

[0005] Therefore, a new direct-reading water meter digit wheel structure is needed, which can achieve reliable position detection without the need for a light-transmitting channel, effectively reduce the impact of ambient temperature changes on measurement accuracy, and meet the installation requirements of the confined space inside the mechanical water meter. Summary of the Invention

[0006] The purpose of this application is to provide a direct-reading water meter digit wheel, a method for detecting the reading, and a water meter, in order to solve the problems mentioned in the background art.

[0007] This application discloses a direct-reading water meter digit wheel based on differential electromotive force sensing signal, including:

[0008] The character wheel stator includes an outer annular structure and an inner annular structure arranged coaxially.

[0009] The character wheel rotor is coaxially sleeved outside the character wheel stator and rotates around the character wheel stator;

[0010] An excitation coil is disposed inside the outer ring structure and is used to generate an alternating magnetic field when an alternating current is applied.

[0011] An induction coil is disposed on the outside of the inner ring structure; the induction coil includes multiple independent induction coil segments, each of which corresponds to a digit position on the digit wheel rotor in the circumferential direction; each induction coil segment has a first terminal, a middle tap, and a second terminal, the middle tap dividing the induction coil segment into a first half-coil segment and a second half-coil segment.

[0012] The iron core is fixed on the character wheel rotor and located in the gap between the excitation coil and the induction coil, and rotates with the character wheel rotor;

[0013] The iron core is configured such that when it rotates with the digit wheel rotor to a position relative to a certain induction coil segment, the magnetic conduction of the iron core changes the magnetic field distribution near that induction coil segment, causing a differential electromotive force value to be generated between the induced electromotive force of the first half-coil segment and the induced electromotive force of the second half-coil segment. The differential electromotive force value is used to indicate the position of the iron core relative to that induction coil segment.

[0014] In a preferred embodiment, the multiple independent induction coil segments are 10 segments, evenly distributed on the outer side of the inner ring structure.

[0015] In a preferred embodiment, when the iron core moves from the second terminal to the first terminal via the intermediate tap, the differential electromotive force value changes from a negative extreme value to zero, and then to a positive extreme value.

[0016] In a preferred embodiment, when multiple direct-reading water meter digit wheels are used in series, the excitation coils of each direct-reading water meter digit wheel are powered sequentially according to a fixed time difference and order, so as to ensure that at the same time, only one set of direct-reading water meter digit wheels is powered and read.

[0017] In a preferred embodiment, both the excitation coil and the induction coil are encapsulated within a waterproof layer.

[0018] In a preferred embodiment, the waterproof layer is made of plastic or rubber material.

[0019] In a preferred embodiment, the excitation coil is a full-turn conductive coil connected to an external AC power source.

[0020] In a preferred embodiment, the iron core is fixed to the inner ring of the digit wheel rotor and corresponds to a specific number position on the digit wheel rotor.

[0021] In a preferred embodiment, the specific digital position is the 0th bit.

[0022] In a preferred embodiment, the core is made of a soft magnetic ferrous material.

[0023] In a preferred embodiment, the induction coil is a printed coil made on a printed circuit board.

[0024] In a preferred embodiment, the surface of the character wheel rotor is marked with 10 numbers from 0 to 9.

[0025] In a preferred embodiment, both the excitation coil and the induction coil are wound with enameled copper wire.

[0026] In a preferred embodiment, the character wheel stator is provided with a fixing part for connection with an external fixing structure.

[0027] In a preferred embodiment, the first terminal, the intermediate tap, and the second terminal of each induction coil segment are connected to an external electromotive force detection circuit.

[0028] In a preferred embodiment, the fixed time difference is 1 ms to 50 ms.

[0029] In a preferred embodiment, the operating frequency of the excitation coil is from 100 Hz to 10 kHz.

[0030] In a preferred embodiment, the electromotive force detection circuit includes an instrumentation amplifier, a bandpass filter, and a peak detection circuit, wherein the common-mode rejection ratio of the instrumentation amplifier is not less than 80 dB.

[0031] In a preferred embodiment, a reading detection method based on the above-mentioned direct-reading water meter dial wheel is proposed, comprising the following steps:

[0032] An alternating current is applied to the excitation coil to generate an alternating magnetic field;

[0033] Obtain the induced electromotive force of the first half-coil segment and the second half-coil segment of each segment of the induction coil;

[0034] Calculate the differential electromotive force value for each segment of the induction coil, wherein the differential electromotive force value is the difference between the induced electromotive force of the first half-coil segment and the induced electromotive force of the second half-coil segment.

[0035] By comparing the differential electromotive force values ​​of each induction coil segment, the target coil segment for generating an effective differential electromotive force signal is determined.

[0036] Based on the polarity and amplitude of the differential electromotive force of the target coil segment, the position of the iron core relative to that induction coil segment is determined, thereby determining the reading of the digit wheel.

[0037] This application also discloses a direct-reading water meter, comprising: a base meter, wherein the base meter is provided with an impeller that rotates with the water flow; and the aforementioned direct-reading water meter digit wheel, wherein the digit wheel rotor of the direct-reading water meter digit wheel is drively connected to the impeller.

[0038] This application achieves a compact nested layout of the excitation coil, induction coil, and iron core in the radial direction by using the coaxial arrangement of the outer and inner annular structures of the stator and the coaxial sleeve of the rotor around the stator. This effectively reduces the radial dimension of a single rotor assembly, making the direct-reading water meter rotor of this application suitable for narrow mechanical metering spaces and facilitating the series installation of multiple digit rotors within a limited space.

[0039] Optionally, this application arranges the excitation coil inside the outer ring structure to generate an alternating magnetic field when AC current is applied, and the induction coil outside the inner ring structure. This arrangement ensures that the alternating magnetic field generated by the excitation coil can effectively cover the area where the induction coil is located, providing a stable excitation magnetic field source for each induction coil segment and ensuring the reliable generation of the induced electromotive force signal.

[0040] Optionally, this application employs a structural design where the iron core is fixed to the digit wheel rotor and rotates with it within the gap between the excitation coil and the induction coil. This design allows the iron core to modulate the magnetic field distribution in the surrounding area through its magnetic permeability during rotation, thus providing a physical basis for generating the differential electromotive force signal. The iron core is made of soft magnetic ferrite material, possessing high permeability and a fast response speed, enabling it to sensitively respond to position changes and generate corresponding magnetic field modulation effects. When the iron core is fixed at a specific digit position on the digit wheel rotor, such as position 0, a definite correspondence is formed between the position of the iron core and the digit reading of the digit wheel rotor, allowing the accurate digit wheel reading to be obtained by detecting the position of the iron core.

[0041] Optionally, this application employs a three-tap structure design where each induction coil segment has a first terminal, a middle tap, and a second terminal, and the middle tap divides the induction coil segment into a first half-coil segment and a second half-coil segment. Combined with the magnetic conductivity of the iron core, this alters the magnetic field distribution near the induction coil segment, allowing a differential electromotive force (EMF) value to be generated between the induced EMF of the first half-coil segment and the induced EMF of the second half-coil segment. Since the two half-coil segments are under essentially the same environmental conditions, the effects of ambient temperature changes and external electromagnetic interference are effectively canceled out as common-mode components in the calculation of the differential EMF value, thus significantly improving the stability and accuracy of the readings under different ambient temperatures and electromagnetic environments. When the induction coil consists of 10 independent induction coil segments evenly distributed on the outer side of the inner ring structure, each induction coil segment corresponds one-to-one with one of the 10 digit positions (0-9) on the digit wheel rotor, achieving complete coverage detection of all digit positions.

[0042] Optionally, this application utilizes the regular change characteristic of the differential electromotive force value from a minimum negative value to zero and then to a maximum positive value when the iron core moves from the second terminal to the first terminal via the intermediate tap. This allows the external electromotive force detection circuit to not only determine which induction coil segment the iron core is near, but also to further determine the precise position of the iron core within that induction coil segment based on the polarity and amplitude of the differential electromotive force value, thereby improving the resolution of position detection.

[0043] Optionally, this application employs a fully sealed waterproof structure design, encapsulating both the excitation coil and the induction coil within a waterproof layer. This allows the direct-reading water meter's digits to utilize standard waterproof encapsulation processes common in the electronics industry, avoiding the light-transmitting channel requirements of photoelectric direct-reading methods. This achieves a completely sealed waterproof encapsulation, significantly improving reliability and lifespan during long-term operation in humid environments. The waterproof layer, made of plastic or rubber, exhibits good compatibility with the insulation layers of the excitation and induction coils, forming a reliable seal.

[0044] Optionally, this application employs a time-division multiplexing power supply mechanism, where the excitation coils of each direct-reading water meter digit wheel are powered sequentially with a fixed time difference and order when multiple direct-reading water meter digit wheels are used in series. This ensures that only one set of direct-reading water meter digit wheels is powered and read at any given time, fundamentally eliminating the electromagnetic crosstalk problem caused by the mutual influence of excitation magnetic fields between adjacent digit wheels and ensuring the accuracy and reliability of multi-digit readings.

[0045] Optionally, this application uses a structure where the excitation coil is a single, continuous conductive coil connected to an external AC power source. This allows the excitation coil to generate a uniformly distributed alternating magnetic field throughout the entire annular region containing the induction coil, ensuring that each segment of the induction coil receives a stable excitation magnetic field. This guarantees the consistency and reliability of the differential electromotive force detection. When the excitation and induction coils are wound with enameled copper wire, they possess excellent conductivity and insulation properties, making them suitable for miniaturized coil structures. When the induction coil is printed on a PCB (printed circuit board), the coil thickness can be further reduced, and the consistency of parameters between each segment of the induction coil can be improved.

[0046] The specification of this application contains numerous technical features distributed across various technical solutions. Listing all possible combinations of these technical features (i.e., technical solutions) would make the specification excessively lengthy. To avoid this problem, the various technical features disclosed in the above-described invention, the various technical features disclosed in the following embodiments and examples, and the various technical features disclosed in the accompanying drawings can be freely combined to form various new technical solutions (all of which are considered to have been described in this specification), unless such a combination of technical features is technically infeasible. For example, one example discloses feature A+B+C, and another example discloses feature A+B+D+E. Features C and D are equivalent technical means that serve the same function, and technically only one needs to be used; they cannot be used simultaneously. Feature E can technically be combined with feature C. Therefore, the solution A+B+C+D should not be considered as described because it is technically infeasible, while the solution A+B+C+E should be considered as described. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the rotor structure of a direct-reading water meter based on a differential electromotive force sensing signal, according to an embodiment of this application.

[0048] Figure 2 This is a schematic diagram of the stator structure of a direct-reading water meter based on a differential electromotive force sensing signal, according to an embodiment of this application.

[0049] Figure 3 This is a schematic diagram of the structure of a direct-reading water meter rotor and stator assembled into a single rotor according to an embodiment of this application based on a differential electromotive force induction signal.

[0050] Figure 4 This is a schematic diagram of a multi-stage serially connected digit wheel structure of a direct-reading water meter based on a differential electromotive force sensing signal, according to an embodiment of this application.

[0051] Figure 5 This is a schematic diagram of the structure of the excitation coil of the direct-reading water meter digit wheel based on the differential electromotive force sensing signal according to an embodiment of this application. The left side is a three-dimensional schematic diagram of the excitation coil 4, and the right side is a cross-sectional schematic diagram of the excitation coil 4 encapsulated in the waterproof layer 6. In the figure, "+" and "-" represent the positive and negative terminals of the excitation coil 4, respectively.

[0052] Figure 6 This is a schematic diagram of the induction coil of a direct-reading water meter based on a differential electromotive force sensing signal, according to an embodiment of this application.

[0053] Figure 7This is a schematic diagram of the differential electromotive force principle of the direct-reading water meter's dial based on the differential electromotive force sensing signal, according to an embodiment of this application. Detailed Implementation

[0054] In the following description, many technical details are presented to help the reader better understand this application. However, those skilled in the art will understand that the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0055] Explanation of some concepts:

[0056] Direct-reading water meter digit wheel: refers to a component that integrates mechanical metering function and electronic signal conversion function. It can retain the mechanical digit wheel display of traditional water meters, and can also directly output an electrical signal representing the current digital reading through internal sensors, without having to calculate the reading through accumulated pulses.

[0057] Differential electromotive force: In this application, it specifically refers to the difference in electromotive force (VAB-VCB) induced in two half-coil segments (the first half-coil segment and the second half-coil segment) separated by a center tap within the same induction coil segment. The magnitude and polarity of this difference are used to characterize the degree of offset of the iron core relative to the center position of the induction coil segment.

[0058] Excitation Coil: refers to the active coil set on the stator, which is used to generate an alternating magnetic field when an alternating current is applied, serving as the energy source and signal carrier of the entire sensor system.

[0059] Induction coil: refers to a passive sensing coil mounted on the stator, used to sense changes in the surrounding magnetic field and output an electrical signal. In this application, it typically comprises multiple independent coil segments with a specific spatial distribution.

[0060] Common-mode interference refers to interference signals that act simultaneously on both input terminals (i.e., both half-coil segments) of a differential circuit and whose amplitude and phase tend to be consistent, such as resistance drift caused by changes in ambient temperature and external far-field electromagnetic radiation.

[0061] The following is a brief summary of some of the innovative aspects of this application:

[0062] In summary, the technical concept of this application stems from an in-depth analysis and systematic solution to the multiple technical contradictions existing in the digitization conversion technology of existing water meter digits. In the application scenarios of water meter digitization in smart buildings and municipal engineering, the digitization conversion of mechanical metering digits has long faced technical contradictions between environmental adaptability and detection accuracy, and between structural compactness and signal reliability. Although photoelectric direct reading can achieve accurate readings, it is difficult to achieve complete sealing and waterproofing due to the requirements of the light transmission channel. Pulse counting has a long-term synchronization deviation problem with the main meter. Eddy current induction is difficult to apply to the confined space of mechanical metering due to the size of the parts required to generate sufficient eddy current effect. Traditional inductive direct reading is easily affected by ambient temperature drift because it uses absolute inductance measurement.

[0063] After in-depth research, the inventors of this application realized that if a three-tap structure could be introduced into the structural design of the induction coil 5, so that each induction coil segment has a first terminal, a middle tap, and a second terminal to form a first half-coil segment and a second half-coil segment, and this structural feature could be combined with the magnetic guiding effect of the iron core 2 fixed to the inner ring of the digit wheel rotor 1, then the differential magnetic field modulation effect generated by the iron core 2 on the two adjacent half-coil segments when the iron core 2 rotates within the gap between the excitation coil 4 and the induction coil 5 could be used to obtain the differential electromotive force value characterizing the position of the iron core 2. The key insight of this technical concept is that when the iron core 2 approaches a certain induction coil segment, due to the high permeability of the iron core 2, the magnetic lines of force tend to form a low magnetic reluctance path through the iron core 2. The electromotive force induced in the half-coil segment closer to the iron core 2 will be relatively increased, while the electromotive force induced in the half-coil segment farther from the iron core 2 will be relatively decreased. Thus, a differential electromotive force value with position indication function is formed between the induced electromotive force of the first half-coil segment and the induced electromotive force of the second half-coil segment.

[0064] The realization of the above-mentioned technical concept relies on the coaxial arrangement of the outer and inner annular structures of the stator 3, the arrangement of the excitation coil 4 inside the outer annular structure, the arrangement of the induction coil 5 outside the inner annular structure, and the coordinated spatial configuration of the iron core 2 rotating with the rotor 1 within the gap between them. It is precisely because of this coaxial, nested, and compact structural layout that the alternating magnetic field generated by the excitation coil 4 can effectively pass through the area where the induction coil 5 is located. Simultaneously, the rotation trajectory of the iron core 2 is precisely located between the excitation coil 4 and the induction coil 5, thus enabling a local modulation effect on the magnetic field distribution in this area through its magnetic permeability. This structural configuration is not a simple spatial superposition of the components, but a systematic design based on the principles of electromagnetic induction and differential signal detection. Any change in the position or structure of any component can lead to a significant deterioration in the differential electromotive force detection effect.

[0065] Furthermore, the differential electromotive force detection method employed in this application represents a fundamental technical difference compared to existing absolute quantity measurement methods. Since the first and second half-coil segments are located within the same induction coil segment and share a common intermediate tap, they operate under essentially the same environmental conditions. Therefore, the effects of ambient temperature changes and external electromagnetic interference on the two half-coil segments are highly consistent, effectively canceling them out as common-mode components when calculating the differential electromotive force value. This technical effect is not solely dependent on the differential operation signal processing method itself, but rather on the organic combination of structural features such as the three-tapped induction coil structure, the specific arrangement of the iron core 2, and the coaxial nested configuration of the excitation coil 4 and the induction coil 5.

[0066] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0067] Through long-term and in-depth research, the inventors of this application have discovered that the technical dilemma faced by existing water meter digit conversion technology stems from inherent technical limitations in the signal conversion principle of existing technical solutions. These limitations lead to an irreconcilable technical contradiction between environmental adaptability, structural compactness, and detection reliability.

[0068] The inventors first conducted an in-depth technical analysis of the photoelectric direct reading method and discovered that the reason this method is easily affected by the internal light environment of the water meter is that the photoelectric sensor relies on the stable transmission and reception of light signals. However, factors such as condensation, water mist, and dust particles in the internal environment of the water meter can scatter, absorb, or block the light signals, resulting in a decrease in the intensity and stability of the light signals received by the sensor. More importantly, there is an essential technical contradiction between the requirements for the setting of the light transmission channel in the photoelectric direct reading method and the completely sealed waterproof packaging. To achieve the transmission of light signals, the light transmission channel must be retained, but the existence of the light transmission channel makes it difficult to achieve a completely sealed waterproof structure. This fundamentally restricts the reliability of the photoelectric direct reading method in humid environments.

[0069] The inventors further analyzed the traditional inductive direct-reading method and discovered that its susceptibility to ambient temperature affects the reading accuracy. The root cause lies in the fact that traditional inductive direct-reading uses an absolute inductance measurement principle, determining the character wheel position by measuring changes in the absolute inductance value. However, the parameters of the inductor are inherently sensitive to temperature. When the ambient temperature changes, parameters such as the coil resistance and the magnetic permeability of the core drift, leading to deviations in the measured absolute inductance value and affecting the accuracy of position determination. The inventors recognized that to fundamentally solve the temperature drift problem, it is necessary to abandon the absolute measurement approach and instead adopt relative or differential measurement techniques, allowing the influence of temperature changes on the measurement to be effectively canceled out as a common-mode component.

[0070] The inventors also noted that existing technologies commonly suffer from electromagnetic crosstalk between adjacent character wheels when multiple character wheels are used in series. After in-depth analysis, they discovered that the cause of this problem is that when the excitation sources of each character wheel are working simultaneously, the excitation magnetic fields of adjacent character wheels will affect each other, resulting in interference components generated by the excitation sources of adjacent character wheels mixed in with the induced signal. The inventors thus realized that an effective way to solve this problem is to adopt a time-division multiplexing power supply mechanism, so that the excitation coils of each character wheel are powered sequentially according to a certain time difference and order, ensuring that only one set of character wheels is in working state at any given time, thereby fundamentally eliminating electromagnetic crosstalk between adjacent character wheels.

[0071] Based on the above in-depth research, the inventors have creatively proposed a technical solution for position detection using differential electromotive force (EMF) induction signals. The core technology of this solution lies in: by setting a three-tapped structure on each induction coil segment, forming a first half-coil segment and a second half-coil segment sharing a common center tap, the differential EMF value characterizing the core position is obtained by utilizing the differential magnetic field modulation effect generated by the iron core rotating with the digit wheel rotor on the two half-coil segments; since the two half-coil segments are under essentially the same environmental conditions, the effects of temperature changes and electromagnetic interference on both are highly consistent, effectively canceling them out as common-mode components when calculating the differential EMF value, thus achieving effective suppression of environmental interference; simultaneously, a coaxial rotor-stator integrated structure is used to achieve a compact layout, a fully sealed waterproof encapsulation is used to improve environmental adaptability, and a time-division multiplexing power supply mechanism is used to eliminate electromagnetic crosstalk when multiple digit wheels are connected in series.

[0072] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0073] This application provides a direct-reading water meter digit wheel based on differential electromotive force induction signal. This direct-reading water meter digit wheel utilizes the principle of electromagnetic induction and differential signal detection to achieve digital conversion of the mechanical metering digit wheel readings. Compared with existing photoelectric direct reading, pulse counting, and eddy current induction methods, this application has significant advantages such as compact structure, strong environmental adaptability, and good anti-interference capability.

[0074] Please see Figures 1 to 7 The direct-reading water meter digit wheel provided in this embodiment mainly includes a digit wheel stator 3, a digit wheel rotor 1, an excitation coil 4, an induction coil 5, and an iron core 2. The following provides a detailed description of each component and their interrelationships.

[0075] I. Type wheel stator

[0076] The stator 3 of the digit wheel is a fixed component of the direct-reading water meter digit wheel of this application, used to support the excitation coil 4 and the induction coil 5. For example... Figure 2 As shown, the stator 3 of the character wheel adopts a double-ring coaxial structure design, including an outer ring structure and an inner ring structure arranged coaxially. An annular gap is formed between the outer ring structure and the inner ring structure, which is used to accommodate the iron core 2 that rotates with the character wheel rotor 1.

[0077] Specifically, the inner side of the outer ring structure has a mounting position for the excitation coil 4, and the outer side of the inner ring structure has a mounting position for the induction coil 5. This double-ring coaxial structure design allows the excitation coil 4, the induction coil 5, and the iron core 2 to be arranged sequentially in the radial direction, forming a compact electromagnetic coupling structure.

[0078] Furthermore, the stator 3 is provided with a fixing part for connection with an external fixed structure, maintaining a coaxial relationship with the rotor 1. In practical applications, the stator 3 can be made of engineering plastic. The reason for choosing engineering plastic is that it has good insulation properties, is easy to precision mold, and has a moderate cost.

[0079] II. Type Wheel Rotor

[0080] The rotor 1 is the rotating component of the direct-reading water meter in this application, used to rotate synchronously with the water meter's turbine and display the metering reading. For example... Figure 1 As shown, the character wheel rotor 1 is coaxially sleeved on the outside of the character wheel stator 3 and can rotate freely around the character wheel stator 3. Figure 3 As shown, the rotor 1 and stator 3 are assembled to form a single complete direct-reading water meter rotor.

[0081] The surface of the digit wheel rotor 1 is marked with 10 numbers from 0 to 9. These numbers are evenly distributed along the circumference of the digit wheel rotor 1, with each number corresponding to a position on the circumference of the digit wheel rotor 1. When the digit wheel rotor 1 rotates with the water meter turbine, the numbers displayed on its surface change accordingly, thus realizing the mechanical metering function.

[0082] Furthermore, the digit wheel rotor 1 can be made of commonly used digit wheel plastics. For example, acrylonitrile-butadiene-styrene copolymer (ABS) or polyoxymethylene (POM) can be selected. These materials have the characteristics of good moldability, low cost, and excellent insulation performance. The digit wheel rotor 1 has a shaft hole at its center for mating with the water meter drive shaft to achieve synchronous rotation with the water meter turbine.

[0083] III. Excitation Coil

[0084] The excitation coil 4 is the magnetic field generating component of the direct-reading water meter's digit wheel in this application, used to generate an alternating magnetic field when alternating current is applied. For example... Figure 2 and Figure 5 As shown, the excitation coil 4 is located inside the outer ring structure of the character wheel stator 3.

[0085] Specifically, the excitation coil 4 is a complete conductive coil, arranged inside the outer ring structure of the stator 3. The positive and negative terminals of the excitation coil 4 are connected to an external AC power supply. When the water meter is working, AC current is applied to the excitation coil 4, generating an alternating magnetic field in the surrounding space. This alternating magnetic field passes through the area where the inner induction coil 5 is located, serving as the excitation source for the induced electromotive force.

[0086] Furthermore, the excitation coil 4 can be wound with enameled copper wire. Enameled copper wire is chosen because of its good conductivity, ease of winding, and moderate cost. The operating frequency range of the excitation coil 4 is preferably 100Hz to 10kHz. Within this frequency range, the induction coil 5 can generate an induced electromotive force signal of sufficient amplitude, while avoiding eddy current losses and skin effect caused by excessively high frequencies. In one specific embodiment, the operating frequency of the excitation coil 4 is 1kHz, and the excitation voltage is 3V AC voltage.

[0087] IV. Induction Coil

[0088] The induction coil 5 is the signal conversion component of the direct-reading water meter's dial wheel in this application, used to convert changes in the magnetic field into a detectable induced electromotive force signal. For example... Figure 2 and Figure 6 As shown, the induction coil 5 is located on the outside of the inner ring structure of the character wheel stator 3.

[0089] The induction coil 5 comprises multiple independent induction coil segments, each corresponding circumferentially to a digit position on the digit wheel rotor 1. More specifically, the induction coil 5 consists of 10 independent induction coil segments, which are evenly distributed on the outer side of the inner ring structure and correspond one-to-one with the 10 digit positions from 0 to 9 on the digit wheel rotor 1.

[0090] A key technical feature of this application is that each induction coil segment has a first terminal, a center tap, and a second terminal. The center tap divides the induction coil segment into a first half-coil segment and a second half-coil segment. This three-tap induction coil structure is crucial for achieving differential electromotive force detection. Figure 6 As shown, the first terminal of each induction coil segment is marked as A, the middle tap is marked as B, and the second terminal is marked as C, thus forming the AB half segment (first half coil segment) and the CB half segment (second half coil segment).

[0091] Furthermore, the first terminal, the middle tap, and the second terminal of each induction coil segment are connected to an external electromotive force detection circuit, so that the detection circuit can collect the induced electromotive force signal of each induction coil segment and perform differential calculation.

[0092] The induction coil 5 can also be wound with enameled copper wire. Alternatively, the induction coil 5 can also be a PCB printed coil, which can further reduce the thickness and improve the consistency of the coil parameters.

[0093] V. Iron Core

[0094] The iron core 2 is the magnetic field modulation component of the direct-reading water meter's dial wheel in this application, used to change the magnetic field distribution in the area near the induction coil 5. For example... Figure 1 As shown, the iron core 2 is fixed on the character wheel rotor 1 and located in the gap between the excitation coil 4 and the induction coil 5, rotating synchronously with the character wheel rotor 1.

[0095] Specifically, the iron core 2 is fixed to the inner ring of the digit wheel rotor 1 and corresponds to a specific digit position on the digit wheel rotor 1. More specifically, this specific digit position can be the 0th position, that is, the iron core 2 is fixed to the inner ring side of the 0th digit position on the digit wheel rotor 1. Of course, in other embodiments, the iron core 2 can also be fixed to other digit positions, as long as the position of the iron core 2 and the digit position on the digit wheel rotor 1 have a definite correspondence.

[0096] The iron core 2 is made of soft magnetic iron material. The reason for choosing soft magnetic iron material is that it has high permeability, low coercivity, and fast response speed. The iron core 2 has high permeability. When it enters the vicinity of a certain induction coil segment, the magnetic field lines tend to pass through the iron core 2 to form a low magnetic reluctance path, which leads to the enhancement of the magnetic field in that region, thereby changing the induced electromotive force of that induction coil segment.

[0097] VI. Waterproof Encapsulation Structure

[0098] To improve the environmental adaptability and service life of the direct-reading water meter's digits, both the excitation coil 4 and the induction coil 5 are encapsulated within a waterproof layer 6. For example... Figure 5 and Figure 6 As shown, the waterproof layer 6 completely encloses and seals the excitation coil 4 and each segment of the induction coil, forming a fully sealed waterproof structure. Figure 5 As shown in the cross-sectional view on the right, the waterproof layer 6 completely covers the excitation coil 4.

[0099] The waterproof layer 6 is made of plastic or rubber materials, such as ABS plastic, silicone rubber, or epoxy resin. The specific material and thickness can be determined according to the waterproof rating requirements. This fully sealed waterproof encapsulation design allows the direct-reading water meter's dial to use the waterproofing process standard in the traditional electronics industry, avoiding the stringent light transmittance requirements of photoelectric direct-reading methods, thereby significantly improving reliability in humid environments.

[0100] VII. Principle of Differential Electromotive Force Induction Detection

[0101] The core innovation of this application lies in using the differential electromotive force induction signal detection principle to achieve the digital conversion of the digit wheel reading. The following is a combination of... Figure 7 This principle will be explained in detail.

[0102] When alternating current is applied to the excitation coil 4, an alternating magnetic field is generated in the region where the induction coil 5 is located, and each segment of the induction coil will generate an induced electromotive force. Since the induction coil segments have the same structure and are symmetrically positioned in the magnetic field, in the absence of the influence of the iron core 2, the induced electromotive forces generated by the first half-coil segment (AB half-coil segment) and the second half-coil segment (CB half-coil segment) of each induction coil segment are approximately equal.

[0103] The iron core 2 is configured such that, when it rotates with the rotor 1 to a position relative to a certain induction coil segment, the magnetic permeability of the iron core 2 alters the magnetic field distribution near that induction coil segment. Due to the high permeability of the iron core 2, the magnetic field near the half-coil segment close to the iron core 2 is enhanced, resulting in an increase in the induced electromotive force (EMF) of that half-coil segment. This creates a differential EMF value between the induced EMF of the first half-coil segment and the induced EMF of the second half-coil segment, which is used to indicate the position of the iron core 2 relative to that induction coil segment.

[0104] More specifically, when core 2 moves from the second terminal (C) to the first terminal (A) via the center tap (B), the differential electromotive force (VAB-VCB) changes from a negative extreme to zero, and then back to a positive extreme. Specifically: when core 2 is near the center tap (B), the magnetic field affecting the first and second half-coil segments is the same, VAB and VCB are equal, and the differential electromotive force is zero; when core 2 is biased towards the first terminal (A), the magnetic field near the first half-coil segment strengthens, VAB increases while VCB relatively decreases, and the differential electromotive force is positive; conversely, when core 2 is biased towards the second terminal (C), the differential electromotive force is negative.

[0105] By detecting the differential electromotive force value and its changing pattern of each induction coil segment, the external electromotive force detection circuit can interpret the position of the iron core 2 relative to the 10 induction coil segments, thereby obtaining the digital reading displayed by the current digit wheel rotor 1.

[0106] This differential electromotive force (EMF) sensing method has significant advantages over existing technologies. It should be noted that existing direct inductance reading methods typically use absolute inductance measurement, which is easily affected by ambient temperature drift. In contrast, this application uses the difference in induced EMF between two half-coil segments under the same excitation source for detection. Temperature and electromagnetic interference, as common-mode signals, are effectively canceled out, thus significantly improving the stability and accuracy of the readings.

[0107] 8. Multi-wheel cascade use

[0108] In practical water meter applications, multiple digits are typically required to display the complete meter reading. This application's direct-reading water meter digit wheel supports the use of multiple digit wheels in series to display multiple digits. For example... Figure 4 As shown, multiple direct-reading water meter digit wheels can be installed in series along the axial direction to form a multi-digit direct-reading water meter digit wheel group.

[0109] When multiple direct-reading water meter digits are used in series, to avoid electromagnetic crosstalk between adjacent digits, the excitation coils 4 of each digit are powered sequentially according to a fixed time difference and order, ensuring that only one set of digits is powered and reading at any given time. This time-division multiplexing power supply mechanism is another important innovation of this application.

[0110] Specifically, the control circuit sequentially supplies power to the excitation coil 4 of each digit wheel, completing the reading acquisition of one digit wheel in each power supply cycle, and then switching to the next digit wheel. In this way, electromagnetic crosstalk between adjacent digit wheels can be fundamentally eliminated, ensuring the accuracy and reliability of multi-digit readings.

[0111] IX. Overall Work Process

[0112] The overall workflow of the direct-reading water meter's dial indicator in this application is as follows:

[0113] First, an alternating current is applied to the excitation coil 4, generating an alternating magnetic field in the region where the induction coil 5 is located. Each segment of the induction coil generates an induced electromotive force under the influence of this alternating magnetic field.

[0114] Then, as the water meter turbine rotates, the digit wheel rotor 1 drives the iron core 2 to rotate in the annular gap between the excitation coil 4 and the induction coil 5. When the iron core 2 rotates to the vicinity of a certain section of the induction coil, the magnetic field distribution near that section of the induction coil changes due to the magnetic conduction of the iron core 2.

[0115] Next, the induced electromotive force (EMF) of the half-coil segment closest to the iron core 2 increases, resulting in a differential EMF value between the first and second half-coil segments of that induction coil segment. An external EMF detection circuit collects the differential EMF values ​​of each induction coil segment.

[0116] Finally, the electromotive force detection circuit interprets the position of the iron core 2 relative to the 10 induction coil segments according to the polarity and amplitude of the differential electromotive force value, thereby determining the digital reading displayed by the current digit wheel rotor 1.

[0117] 10. Key Parameter Description

[0118] To enable those skilled in the art to implement the technical solution of this application, the key parameters are described below by way of example.

[0119] Regarding the time-division multiplexing power supply parameters, when multiple direct-reading water meter digits are connected in series, the excitation coil 4 of each digit is powered sequentially according to the time-division multiplexing method. The fixed time difference refers to the time interval between the start times of power supply to the excitation coils of two adjacent digits. In one specific embodiment, the reading acquisition period for a single digit is 5ms, and the fixed time difference is 5ms; that is, after the first digit is powered on and completes its reading, the second digit begins its power supply 5ms later. For a water meter with 5 digits connected in series, the total time to complete one full reading is approximately 25ms.

[0120] Regarding the amplitude of the differential electromotive force (EMF) signal, under the above excitation parameters, when the core 2 is completely positioned at the first terminal (A) of a certain induction coil segment, the differential EMF value (VAB-VCB) reaches a positive extreme value, typically approximately +50mV to +200mV; when the core 2 is completely positioned at the second terminal (C), the differential EMF value reaches a negative extreme value, typically approximately -50mV to -200mV; when the core 2 is positioned at the intermediate tap (B), the differential EMF value is close to zero. The specific values ​​are related to factors such as the operating frequency of the excitation coil, the number of coil turns, and the core material and dimensions.

[0121] Regarding the embodiment of the electromotive force detection circuit, the electromotive force detection circuit can be implemented using a differential amplifier circuit, specifically including: a multiplexer for sequentially selecting the signals of each induction coil segment; an instrumentation amplifier for differentially amplifying the voltage (VAB) between the first terminal and the center tap and the voltage (VCB) between the second terminal and the center tap, with a common-mode rejection ratio of not less than 80dB to effectively suppress temperature drift and electromagnetic interference; a bandpass filter for filtering out interference signals other than the excitation frequency; a peak detection circuit or synchronous demodulation circuit for extracting the amplitude and polarity information of the differential electromotive force; and an analog-to-digital converter for converting the analog signal into a digital signal for processing by the microcontroller.

[0122] The specific interpretation logic is as follows: First, the detection circuit scans 10 coil segments and identifies the coil segment with a differential electromotive force (EMF) value significantly greater than the background noise threshold as the active coil segment; then, the differential EMF value of the active coil segment is measured, and the polarity of the differential EMF value is used to determine whether the iron core is biased towards end A or end C, and the precise position of the iron core is determined based on the amplitude; finally, using the pre-calibrated differential EMF and position characteristic curve, the voltage value of the differential EMF is mapped to a precise angular position, thereby achieving high-precision direct reading measurement.

[0123] The direct-reading water meter digit wheel based on differential electromotive force induction signal in the above embodiments has the following beneficial effects: First, no light transmission requirement. Unlike photoelectric direct reading, this application uses electromagnetic induction principle for signal conversion, which does not require a light transmission channel. It can be completely waterproofed using traditional electronic industry standards, avoiding interference from environmental factors such as condensation, water mist, and contaminants inside the water meter. Second, strong anti-interference capability. This application uses differential signal detection, determining the core position by detecting the difference in induced electromotive force between the two half-coil segments rather than the absolute value. Ambient temperature and electromagnetic interference are effectively canceled out as common-mode signals, significantly improving the stability of readings under different environmental conditions. Third, compact structure. This application adopts a coaxial rotor-stator integrated structure design, integrating the excitation coil and induction coil on the inner and outer ring structure of the digit wheel stator, forming a compact nested structure. This effectively reduces the radial dimension of the digit wheel assembly, facilitating the series installation of multiple digit wheels within the limited space of a mechanical meter. Fourth, reliable multi-digit wheel collaborative operation. This application adopts a time-division multiplexing power supply mechanism, in which the excitation coils of each character wheel are powered sequentially according to a fixed time difference and order, which fundamentally eliminates electromagnetic crosstalk between adjacent character wheels and ensures the accuracy of multi-digit readings.

[0124] In summary, this application, by employing the differential electromotive force induction signal detection principle, coaxial rotor-stator integrated structure, time-division multiplexing power supply mechanism, and fully sealed waterproof packaging design, realizes a direct-reading water meter digit wheel with high precision, high reliability, and good environmental adaptability, providing a new technical solution for water meter digital processing technology in intelligent buildings and municipal engineering.

[0125] It should be noted that in this patent application, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one" does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. In this patent application, if it refers to performing an action according to an element, it means performing the action at least according to that element, including two cases: performing the action only according to that element, and performing the action according to that element and other elements. Expressions such as "multiple," "repeatedly," and "various" include two, two times, two kinds, and more than two, more than two times, and more than two kinds.

[0126] All documents mentioned in this application are considered to be incorporated in their entirety into the disclosure of this application so that they can serve as a basis for modifications if necessary. Furthermore, it should be understood that after reading the foregoing disclosure of this application, those skilled in the art can make various alterations or modifications to this application, and these equivalent forms also fall within the scope of protection claimed in this application.

Claims

1. A direct-reading water meter digit wheel based on differential electromotive force induction signal, characterized in that, include: The character wheel stator includes an outer annular structure and an inner annular structure arranged coaxially. The character wheel rotor is coaxially sleeved outside the character wheel stator and rotates around the character wheel stator; An excitation coil is disposed inside the outer ring structure and is used to generate an alternating magnetic field when an alternating current is applied. An induction coil is disposed on the outside of the inner ring structure; the induction coil includes multiple independent induction coil segments, each of which corresponds to a digit position on the digit wheel rotor in the circumferential direction; each induction coil segment has a first terminal, a middle tap, and a second terminal, the middle tap dividing the induction coil segment into a first half-coil segment and a second half-coil segment. The iron core is fixed on the character wheel rotor and located in the gap between the excitation coil and the induction coil, and rotates with the character wheel rotor; The iron core is configured such that when it rotates with the character wheel rotor to a position relative to a certain induction coil segment, the magnetic conduction of the iron core changes the magnetic field distribution near that induction coil segment, so that a differential electromotive force value is generated between the induced electromotive force of the first half-coil segment and the induced electromotive force of the second half-coil segment, and the differential electromotive force value is used to indicate the position of the iron core relative to that induction coil segment. Furthermore, the multiple independent induction coil segments are 10 segments, evenly distributed on the outer side of the inner ring structure; Furthermore, when the iron core moves from the second terminal to the first terminal via the intermediate tap, the differential electromotive force value changes from a negative extreme value to zero, and then to a positive extreme value.

2. The direct-reading water meter dial wheel as described in claim 1, characterized in that, When multiple direct-reading water meter digit wheels are used in series, the excitation coils of each direct-reading water meter digit wheel are powered sequentially according to a fixed time difference and order, so as to ensure that at the same time, only one set of direct-reading water meter digit wheels is powered and read.

3. The direct-reading water meter dial as described in claim 1, characterized in that, Both the excitation coil and the induction coil are encapsulated within a waterproof layer.

4. The direct-reading water meter dial wheel as described in claim 3, characterized in that, The waterproof layer is made of plastic or rubber material.

5. The direct-reading water meter dial as described in claim 1, characterized in that, The excitation coil is a full-turn conductive coil that is connected to an external AC power supply.

6. A method for detecting the reading of a direct-reading water meter based on the dial of claim 1, characterized in that, Includes the following steps: An alternating current is applied to the excitation coil to generate an alternating magnetic field; Obtain the induced electromotive force of the first half-coil segment and the second half-coil segment of each segment of the induction coil; Calculate the differential electromotive force value for each segment of the induction coil, wherein the differential electromotive force value is the difference between the induced electromotive force of the first half-coil segment and the induced electromotive force of the second half-coil segment. By comparing the differential electromotive force values ​​of each induction coil segment, the target coil segment for generating an effective differential electromotive force signal is determined. Based on the polarity and amplitude of the differential electromotive force of the target coil segment, the position of the iron core relative to that induction coil segment is determined, thereby determining the reading of the digit wheel.

7. A direct-reading water meter, characterized in that, include: A base plate, wherein an impeller is provided inside the base plate and rotates with the water flow; as well as The direct-reading water meter impeller as described in any one of claims 1 to 5, wherein the impeller rotor of the direct-reading water meter impeller is connected to the impeller drive.

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