Flow sensor for determining flow rate of fluid flowing in flow direction
By combining temperature and ultrasonic signal propagation time in the flow sensor, the evaluation module calculates the mixing ratio and flow rate, solving the measurement error problem caused by the mixing ratio changes in the prior art, realizing accurate flow rate detection and reducing costs.
Patent Information
- Application Number
- CN202390000117.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Priority Date
- 2022-03-29
- Filing Date
- 2023-01-31
- Publication Date
- 2024-12-13
- Estimated Expiration
- 2033-01-31
AI Technical Summary
Existing ultrasonic flow sensors have difficulty accurately measuring the fluid flow rate at which the mixing ratio changes, resulting in large measurement errors and additional physical correction terms make the sensor relatively expensive.
A flow sensor including a temperature module, a first ultrasonic module, a second ultrasonic module and an evaluation module is designed. By measuring the propagation time and temperature of the ultrasonic signal, the evaluation module calculates the mixing ratio and flow rate according to the stored relationship table or formula to provide correction. Values to compensate component tolerances.
It realizes dynamic adjustment of flow rate measurement according to the mixing ratio, which reduces costs, improves measurement accuracy and reliability, and is suitable for fluid flow rate detection of different mixing ratios.
Smart Images
Figure CN222166211U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to a flow sensor for determining the flow velocity of a fluid flowing along a flow direction. Background Art
[0002] A large number of flow sensors or flow meters are known from the prior art.
[0003] Flow sensors based on the ultrasonic measuring principle, as explained, for example, in DE 10 2019 009 033 A1, generally have the problem that the flow rate can only be determined accurately for a specific fluid or a specific and previously known mixture.
[0004] Such sensors usually provide for determining the propagation times of sound in two opposite directions along a measuring section inclined to the fluid flow direction, determining the difference between them as the propagation time difference, and determining the flow velocity from this propagation time difference, for example from a table. However, the table is limited to only one mixing ratio or a mixture previously known as a fluid.
[0005] These fluids typically consist of water and an antifreeze agent such as ethylene glycol, but the mix ratio may vary depending on the application as well as external factors.
[0006] If the composition or mixture changes, the relationship shown in the table is no longer correct and an incorrect flow rate is determined. The greater the deviation of the actual mixture from the mixture assumed in the table, the greater the measurement error.
[0007] The ultrasonic flow sensor according to EP 2 641 071 B1 provides an additional physical correction term, such as a heat flow, to correct the individually determined flow velocity, which, however, makes the flow sensor relatively expensive. Utility Model Content
[0008] Therefore, an object of the present invention is to overcome the above disadvantages and to provide a cost-effective flow sensor which is capable of determining the flow rate according to the mixing ratio of the mixture.
[0009] This object is achieved through one aspect of the utility model.
[0010] Therefore, according to the utility model, a flow sensor is proposed, which is used to determine the flow rate of a fluid flowing in a flow direction, in particular the flow rate of a fluid flowing through a flow sensor. The fluid is a mixture mixed according to a mixing ratio, which is preferably basically composed of two (main) components. In particular, the mixture can have water and antifreeze, such as ethylene glycol, as components. In this case, the mixture should also be understood as it can also be composed of 100% of one component, in particular water. The fluid is preferably composed of 50% to 100% water, so that the proportion of antifreeze or ethylene glycol can be 0% to 50%. However, such a mixture or fluid can also preferably contain a small amount of other components or impurities. The proposed flow sensor has a temperature module for measuring the temperature of the fluid, a first ultrasonic module, a second ultrasonic module and an evaluation module. The evaluation module can also be understood as an evaluation unit or an evaluation electronic device. The measurement section extending through the fluid spans between the first ultrasonic module and the second ultrasonic module, which extends at least proportionally along the flow direction, that is, inclined to the flow direction. Therefore, the first ultrasonic module is preferably arranged upstream of the second ultrasonic module relative to the flow direction. The first ultrasonic module and the second ultrasonic module are designed to determine a first sound propagation time from the first ultrasonic module to the second ultrasonic module along the measuring section and a second sound propagation time from the second ultrasonic module to the first ultrasonic module along the measuring section. In addition, the evaluation module is designed to determine the mixing ratio of the fluid based on the temperature, the first sound propagation time and the second sound propagation time. Based on the now known mixing ratio, the evaluation module is further designed to determine the flow rate based on the mixing ratio, the temperature, the first sound propagation time and the second sound propagation time.
[0011] The first sound propagation time can thus be determined by the first ultrasonic module generating a first ultrasonic signal in a first direction along the measurement section and measuring the propagation time of the first ultrasonic signal from the first ultrasonic module to the second ultrasonic module. Similarly, the second sound propagation time can be determined by the second ultrasonic module generating a second ultrasonic signal in a second direction opposite to the first direction and measuring the propagation time from the second ultrasonic module to the first ultrasonic module.
[0012] The measurement of the propagation time can be performed jointly by the first and second ultrasound modules or also by the evaluation module. To this end, the ultrasound modules can be directly connected to one another and / or at least one of the ultrasound modules can be connected to the evaluation module for data exchange.
[0013] The mixing ratio is then determined as a function of the first and second propagation times and the temperature, and the flow rate can thus be determined together with the propagation time.
[0014] Therefore, the basic concept of the present invention can be summarized as follows: the mixture and the flow rate of the mixture or fluid are indirectly (i.e. implicitly) determined by three related measured variables (first propagation time, second propagation time, temperature), and their relationship in the evaluation module is stored in the form of a model, a formula, one or more charts or tables.
[0015] When stored in table form or as one or more graphs, the relationships stored therein may have been determined by a series of measurements and / or tests previously performed.
[0016] The flow rate is preferably understood to mean the volume flow through the flow sensor, so that in the determination in particular the flow cross section provided by the flow sensor and through which the fluid flows can also be taken into account.
[0017] The evaluation module according to the invention is designed to determine the total propagation time as the sum of the first sound propagation time and the second sound propagation time.
[0018] In addition, it is provided that the relationship between the mixing ratio, the temperature, the first sound propagation time and the second sound propagation time in the form of a table is stored in the evaluation module. This relationship is directly stored as a relationship between the mixing ratio, the temperature and the total propagation time, so that the mixing ratio can be determined using the previously determined total propagation time and the temperature of the fluid. This relationship preferably involves a combination of two components. For example, the relationship of a mixture of water and ethylene glycol. In addition, additional or further relationships of other mixtures can also be stored in the evaluation module, so that, for example, at startup, which (main) components constitute the mixture flowing through the flow sensor can be set.
[0019] According to the invention, a first table or matrix is stored in the evaluation module as such a relation, in which a large number of mixing ratios depending on temperature and total propagation time are stored and from which the mixture can be determined and / or interpolated. With reference to this table, a plurality of tables can be stored in the evaluation module, wherein, for example, at startup, it can be selected which table should be used to determine the mixing ratio.
[0020] Once the total propagation time and the temperature have been determined, the mixing ratio can be determined from the table. It is not necessary to store the mixing ratio for each possible total propagation time or for each possible temperature. Instead, the evaluation module can be designed to calculate intermediate values from the stored values, i.e. to interpolate the mixing ratio from the known values.
[0021] For such a table, the composition of the fluid is preferably known and predetermined.Thus, the first table preferably takes into account the dependency or relationship of a mixture of water and an antifreeze agent, such as ethylene glycol.
[0022] Furthermore, the evaluation module is designed to determine the propagation time difference as the difference between the first sound propagation time and the second sound propagation time. Preferably, the smaller sound propagation time is subtracted from the larger sound propagation time. If the first ultrasound module is arranged upstream of the second ultrasound module along the flow direction or along a flow determined by the fluid, the propagation time difference is determined by subtracting the first acoustic propagation time from the second acoustic propagation time. This value can be simply derived regardless of which sound propagation time is subtracted from the other.
[0023] Furthermore, a relationship between the mixing ratio, the temperature, the first sound propagation time and the second sound propagation time is stored in the evaluation module in the form of a table. This relationship is stored directly as a link between the mixing ratio, the temperature and the propagation time difference, so that the flow rate can be determined using the previously determined mixing ratio, the temperature and the propagation time difference. Since the flow rate can be determined for different mixing ratios, a large number of relationships can also be stored in the evaluation module, each relationship being applicable to a mixing ratio.
[0024] According to the invention, at least one second table or matrix is stored in the evaluation module as such a relationship, in which a large number of flow rates are stored as a function of the mixing ratio, the temperature and the propagation time difference, and the flow rate can be determined and / or interpolated from the second table or matrix. The flow rate corresponds in particular to the volume flow of the fluid through the flow sensor and can be measured, for example, in l / h. Preferably, a large number of tables are stored, from which the flow rates for different mixing ratios can be determined.
[0025] In the evaluation module, a correction value can also be stored, which correction value can be determined, for example, at startup of the flow sensor and indicates a deviation of the flow determined by the second table from the actual flow. The correction value is particularly intended to compensate for component tolerances caused by production, so that the correction value is component-specific and can be determined during production or startup and intermittently during operation as required. Therefore, in an advantageous refinement, the evaluation module is designed to apply the correction value to the flow rate determined from the second table, in order to thereby determine the actual flow rate from the (theoretical) flow rate determined according to the second table.
[0026] The flow sensor or its evaluation module can also be designed to repeatedly determine the mixing ratio at predetermined and preferably regular intervals, so that changes in the mixing ratio can be recognized and taken into account when determining the flow.
[0027] The features disclosed above may be combined in any way as long as this is technically feasible and they do not contradict each other. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Other advantageous improvements of the utility model are another aspect of the utility model, or are shown in more detail below in conjunction with the description of the preferred embodiment of the utility model with reference to the accompanying drawings. The accompanying drawings show:
[0029] Figure 1 It is a structural schematic diagram of the flow sensor;
[0030] Figure 2 is a schematic flow chart of the flow determination by the evaluation module. DETAILED DESCRIPTION
[0031] The accompanying drawings are exemplary schematic diagrams. The same reference numerals in the accompanying drawings represent the same functions and / or structural features.
[0032] Figure 1 The flow sensor 1 shown has a temperature sensor or temperature module 10 for determining the temperature T of a fluid flowing through the flow sensor 1 along a flow direction S. In addition, two ultrasonic modules 11, 12 are provided, between which a measuring section X is spanned, and the fluid passes through the measuring section X obliquely with respect to the flow direction S, so that the measuring section X extends proportionally along the flow direction S. The first ultrasonic module 11 is arranged upstream of the second ultrasonic module 12 with respect to the flow direction S, or the second ultrasonic module 12 is arranged downstream of the first ultrasonic module 11.
[0033] Such an ultrasonic module is also already provided in conventional flow sensors based on the ultrasonic measuring principle, by means of which the sound propagation time of the ultrasonic signal in both directions of the measuring section X can be determined. However, based on the sound propagation time determined in this way, the flow rate cannot be accurately determined if the mixture flowing through the flow sensor 1 is unknown or changes.
[0034] It is therefore proposed that the flow sensor 1 has an evaluation module 13 which is designed to determine the mixing ratio of the fluid or mixture flowing through the flow sensor 1 and to determine the flow rate based on this mixing ratio.
[0035] For this purpose, the evaluation module 13 is connected to the temperature sensor 10 and to at least one of the ultrasound modules 11, 12 to enable data exchange. Figure 1 In the variant shown, the evaluation module 13 is connected to both ultrasound modules 11 , 12 , wherein a data connection between the ultrasound modules 11 , 12 is absolutely necessary only if not both ultrasound modules 11 , 12 are connected to the evaluation module 13 .
[0036] The first ultrasonic module 11 and the second ultrasonic module 12 are jointly designed to generate ultrasonic pulses or ultrasonic signals along two directions of the measurement section X, and measure a first propagation time t1 of the ultrasonic signal from the first ultrasonic module 11 to the second ultrasonic module 12 in the first direction and a second propagation time t2 of the ultrasonic signal from the second ultrasonic module 12 to the first ultrasonic module 11 in the second direction.
[0037] Furthermore, the evaluation module 13 is designed to determine the mixing ratio and the flow rate of the fluid or mixture based on the temperature T and the first sound propagation time t1 and the second sound propagation time t2, such as Figure 2 Shown schematically.
[0038] For this purpose, at least a first table 21 is stored in the evaluation module 13, which indicates the mixing ratio of the fluid for a large number of pairs of total propagation time Σt and temperature T. The first table 21 thus relates to mixtures of two known components, and in particular to mixtures of water and ethylene glycol. In the evaluation module 13, a plurality of first tables 21 can also be stored for mixtures of two components, in which case it is then set, in particular when the flow sensor 1 is started, which first table 21 is used or which components the mixture consists of.
[0039] The evaluation module 13 then forms the total propagation time Σt as the sum of the first sound propagation time t1 and the second sound propagation time t2. The mixing ratio is then determined from the value pair of temperature T and total propagation time Σt. Figure 2 An example of a 50% glycol ratio in the mixture is shown, so the mix ratio of water and glycol is 50 / 50.
[0040] Although shown as a table, the relationship between the temperature T and the total propagation time Σt for determining the mixing ratio may also be stored as, for example, a formula, a matrix, a two-dimensional or three-dimensional graph.
[0041] Furthermore, it is not necessary to specify a mixing ratio for each possible value pair in the evaluation module 13. Instead, the mixing ratio of a value pair can be interpolated or extrapolated from the mixing ratios of adjacent value pairs stored in the first table 21.
[0042] Based on the determined mixing ratio, a second table 22 stored in the evaluation module 13 is then determined from a plurality of second tables 22 , which second table 22 describes the flow rate Y based on the determined mixing ratio.
[0043] The relationship described in the second table 22 does not have to be stored in the form of a table, but may also be stored in the evaluation module 13 in the form of a formula, a matrix, or a two-dimensional or three-dimensional graph.
[0044] The evaluation module 13 is designed to determine the propagation time difference Δt from the difference between the first sound propagation time t1 and the second sound propagation time t2. The flow rate Y can then be determined, for example in l / h, from the value pair of temperature T and propagation time difference Δt.
[0045] In general, the flow velocity of the fluid through the flow sensor 1 can be inferred from the propagation time difference Δt through the evaluation module 13. Furthermore, the density of the fluid can be determined from the temperature T and the mixing ratio in the evaluation module 13 and together with the flow diameter stored in the evaluation module 13, the volume of the fluid flowing through the flow sensor 1 at a predetermined time can be determined. These relationships can be contained in the second table 22 and thus taken into account.
[0046] The implementation of the invention is not limited to the preferred exemplary embodiments given above. On the contrary, many variants can be envisaged which also utilize the proposed solution even in fundamentally different designs.
Claims
1. A flow sensor (1) for determining a flow rate (Y) of a fluid flowing in a flow direction (S), the fluid being a mixture mixed according to a mixing ratio, The flow sensor (1) comprises a temperature module (10) for measuring the temperature (T) of the fluid, a first ultrasound module (11), a second ultrasound module (12) and an evaluation module (13). wherein a measuring section (X) extending through the fluid and extending at least proportionally in the flow direction (S) spans between the first ultrasonic module (11) and the second ultrasonic module (12), The first ultrasonic module (11) and the second ultrasonic module (12) are designed to determine a first sound propagation time (t1) from the first ultrasonic module (11) to the second ultrasonic module (12) along the measuring section (X) and a second sound propagation time (t2) from the second ultrasonic module (12) to the first ultrasonic module (11) along the measuring section (X), wherein the evaluation module (13) is designed to determine the mixing ratio of the fluid based on the temperature (T), the first sound propagation time (t1) and the second sound propagation time (t2), wherein the evaluation module (13) is designed to determine the flow rate (Y) based on the mixing ratio, the temperature (T), the first sound propagation time (t1) and the second sound propagation time (t2), wherein the evaluation module (13) is designed to determine a total propagation time (Σt) as the sum of the first sound propagation time (t1) and the second sound propagation time (t2), and to determine a propagation time difference (Δt) as the difference between the first sound propagation time (t1) and the second sound propagation time (t2), wherein a first table (21) is stored in the evaluation module, in which a plurality of mixing ratios are stored which are dependent on the temperature (T) and the total propagation time (Σt), and from which the mixing ratios can be determined and / or interpolated, And wherein a second table (22) is stored in the evaluation module (13), in which a large number of flow rates (Y) are stored depending on the mixing ratio, the temperature (T) and the propagation time difference (Δt), and the flow rate (Y) can be determined and / or interpolated based on the second table.