Fluid counter

Abstract

Fluid meter, namely heat quantity meter (1) for recording the quantity of cold and / or heat of a fluid, for installation in a supply line (20) or return line (21) of a fluid piping system, comprising - a connection housing (2), - a measuring arrangement for determining flow rates, - a control and evaluation unit (3) as well as - a first temperature sensor (4) which is intended for installation in the flow line (20) and is intended there for determining the temperature in the flow line (20), - a second temperature sensor (5), which is intended for installation in the return line (21) and is intended there for determining the temperature in the return line (21), - wherein a means for determining the temperature of the connection housing (2) of the fluid meter is provided, - wherein a temperature difference between the temperature of the connection housing (2) of the fluid meter and at least one of the temperatures of the first (4) and second temperature sensor (5) can be determined, wherein the control and evaluation unit (3) determines, on the basis of the determined temperature difference between the temperature of the fluid meter and at least one of the temperatures of the first and second temperature sensors (4, 5), which of the temperature sensors (4, 5) is installed in the supply line (20) or return line (21), wherein the measuring arrangement for determining the flow rate is provided as a means for determining the temperature of the connection housing (2) of the fluid meter, where the temperature sensors (4, 5) are automatically assigned to the flow (20) or return (21), wherein the temperature of the connection housing (2) of the fluid meter is determined on the basis of a temperature-dependent transit time of an ultrasonic signal in the fluid, and wherein a look-up table is provided in which the transit times of the ultrasonic signal in the fluid are stored as a function of the corresponding temperature of the fluid and / or the connection housing (2) of the fluid meter and the temperature to be determined of the connection housing (2) of the fluid meter can be derived from the transit time of the ultrasonic signal and the look-up table.

Description

[0001] The present invention relates to a fluid meter, in particular a heat meter for recording the amount of cold and / or heat of a fluid, according to claim 1, and to a method for operating a fluid meter. Technological background

[0002] Fluid meters are measuring devices used to determine the flow rate of a fluid, such as water meters, gas meters, heat meters, or similar devices. These fluid meters or flow sensors are typically installed in a fluid piping system. A heat meter, on the other hand, is used to determine the energy in the form of heat or cold, which is supplied to a consumer via a heating circuit or extracted via a heat exchanger with a cooling circuit. The energy or heat energy is determined from the fluid's volumetric flow rate and the temperature difference between the temperature in the supply line (i.e., in the direction of fluid flow before the consumer) and the temperature in the return line (i.e., in the direction of fluid flow after the consumer).

[0003] The volumetric flow rate is typically determined using a measuring device, which is housed, for example, in a fluid meter casing. This measuring device can be mechanical (with an impeller) or static, such as an ultrasonic flow meter. With ultrasonic flow meters, the flow rate can be determined, for example, using the transit-time difference method. This method utilizes the effect that sound waves emitted by at least one ultrasonic transducer, both with and against the flow direction of the fluid, have different transit times due to the fluid flow. This allows the transit-time difference to be determined, which can then be used, for example, to calculate the average flow velocity of the fluid. This average velocity, in conjunction with the flow cross-section, is then used to determine the flow rate.

[0004] In heat meters of this type, the temperature difference between the flow and return lines is determined, for example, using temperature sensors. The fluid meter can be located in either the flow or return line. Two temperature sensors, one in the flow and one in the return, are typically used to determine the temperature difference. One of the temperature sensors (the device-side sensor) can, for example, be housed within the fluid meter casing. Depending on the installation location of the fluid meter, the device-side sensor then determines the flow or return temperature at the fluid meter casing, while the other temperature sensor, connected to the fluid meter via a cable, determines the other flow or return temperature. The installation and arrangement of the temperature sensors and the flow sensor is very complex. Consequently, installation and configuration errors frequently occur, such as...This can be caused by swapping the temperature sensors or incorrectly assigning or configuring them for determining the flow and return temperatures. Especially in designs where the device-side temperature sensor is not integrated into the fluid meter housing, installation personnel very frequently mix up the temperature sensors, leading to installation errors. Such installation errors typically cause the heat meter to malfunction, which can only be rectified through additional time-consuming and costly modifications or reconfiguration. Printed state of the art

[0005] German patent DE 10 2015 001 379 A1 describes a flow meter for measuring the heat quantity of a flowing fluid, which is installed in a supply line containing the fluid. The flow meter comprises a measuring arrangement and a control and evaluation unit for acquiring flow rate data. Based on the flow rate data, the control and evaluation unit determines the installation-dependent flow direction. The flow meter also has a temperature measuring device, which includes two temperature sensors that determine the temperature difference between the supply temperature and the return temperature. Furthermore, a third temperature sensor is provided, located on or inside the flow meter housing, which determines the temperature of the flow meter itself.The temperature difference between the third temperature sensor and the other two temperature sensors is measured to determine the flow meter's installation location (supply or return). Furthermore, during self-configuration, the first and second temperature sensors can be assigned to the supply or return based on the temperature difference between the supply and return temperatures. However, the design of the fluid meter with a third temperature sensor can lead to costly problems. For example, if the third temperature sensor is located externally, significant temperature differences between the fluid temperature and the ambient temperature can cause measurement errors. Additionally, if the third temperature sensor is located inside the housing, the entire flow meter may need to be replaced.

[0006] DE 29 49 346 A1, DE 10 2011 087 215 A1 and EP 2 000 784 A1 each describe methods for measuring heat flux, in which the temperature is determined from the functional relationship between the speed of sound and the temperature of the fluid in question, thereby avoiding the need for temperature measurement using a temperature sensor.

[0007] EP 2 000 788 A1 discloses an energy calculator with installation error detection. Installation error detection is based on the determined temperature or flow direction of the medium. A detected installation error is displayed on a screen.

[0008] From DE 10 2010 011 272 A1, an energy meter is known in which both a positive and negative flow rate as well as a positive and negative temperature difference between the supply and return lines can be detected and displayed on a display device. One of the two temperature sensors is located directly on the fluid meter. Object of the present invention

[0009] The object of the present invention is to provide a fluid meter and a method for operating a fluid meter in which the installation and maintenance costs are reduced cost-effectively and operational reliability is improved. Solution to the task

[0010] The aforementioned problem is solved by the entire teaching of claim 1 and the dependent claim. Advantageous embodiments of the invention are claimed in the dependent claims.

[0011] The fluid meter according to the invention is, in particular, a heat meter for measuring the amount of heat and / or cold in a preferably flowing fluid. The fluid meter is designed for installation in the supply or return line of a fluid piping system. Furthermore, the fluid meter comprises a connection housing for connecting the fluid meter to the fluid piping system, a measuring device for determining the flow rate, a control and evaluation unit, and a first and a second temperature sensor. The temperature sensors are each designed for installation in the supply or return line, e.g., by means of a thermowell. Depending on their respective installation location (supply or return), the first and second temperature sensors serve to determine the supply temperature or the return temperature, respectively.Furthermore, a means for determining the temperature of the fluid meter is provided, whereby a temperature difference between the temperature of the fluid meter and at least one of the temperatures of the first and second temperature sensors can be determined. Subsequently, based on the determined temperature difference(s), it can be determined which of the temperature sensors is installed in the flow or return line, i.e., which temperature sensor is used or configured to determine the flow temperature and which to determine the return temperature. According to the invention, the measuring arrangement for determining the flow rate is provided as a means for determining the temperature of the fluid meter, i.e., essentially for determining the temperature of the connection housing inside the connection housing. This has the advantage that no additional temperature sensors are required to determine the fluid meter temperature.This significantly reduces installation and maintenance costs, for example, by eliminating the need for an additional temperature sensor and its calibration. According to the invention, the temperature sensors are automatically assigned to the flow or return line. This prevents installation errors caused by personnel confusing the temperature sensors. Accordingly, after installation and temperature difference measurement, the temperature sensors are automatically assigned to the flow or return line, for example, by the control and evaluation unit. Therefore, it is essentially irrelevant which temperature sensor is installed in the flow and which in the return line. This further improves installation reliability.

[0012] Preferably, the measuring arrangement is an ultrasonic measuring arrangement with at least one ultrasonic transducer and an ultrasonic measuring section. Accordingly, the flow rate can be determined, for example, by measuring the transit time difference.

[0013] Preferably, the temperature sensor whose temperature has a smaller temperature difference than the temperature of the fluid meter's connection housing is assigned to the same installation location as the fluid meter, i.e., the supply or return line. The assignment of the temperature sensors can be carried out either by a process of elimination based on determining the temperature difference between the temperature of the fluid meter's connection housing and the temperature of only one temperature sensor, or alternately or simultaneously based on determining the temperature difference between the temperature of the fluid meter's connection housing and the temperature of both temperature sensors.

[0014] The temperature sensors are simply positioned during installation in the fluid piping system so that either the temperature of the first or the second sensor corresponds at least substantially to the temperature of the fluid meter's connection housing. This allows installation errors of the temperature sensors to be corrected during the installation process. For example, this prevents the temperature sensor installed at the fluid meter's location from being positioned too far away.

[0015] According to the invention, the temperature of the fluid meter is determined based on the temperature-dependent transit time of an ultrasonic wave or an ultrasonic burst in the fluid. Preferably, the ultrasonic waves of the ultrasonic transducers of the measuring arrangement for flow rate determination are used for this purpose, the transit time of which can vary along the ultrasonic measuring path depending on the temperature.

[0016] According to the invention, a look-up table is provided to determine the temperature of the connection housing of the fluid meter. This table contains transit times as a function of the corresponding temperature. Based on the determined transit time of the ultrasonic signal, the corresponding temperature can thus be read and / or calculated. The look-up table can, for example, be stored in a memory of the fluid meter or the control and evaluation unit.

[0017] Furthermore, a malfunction can be detected if the temperature of the sensor located at the fluid meter's installation point deviates significantly from the temperature of the fluid meter's connection housing. For example, this occurs when the fluid meter is installed in the supply line and its temperature differs significantly from the supply line temperature, or when the fluid meter is installed in the return line and its temperature differs significantly from the return line temperature. This allows for the easy detection of incorrect installation during both the installation and operation phases, thus significantly improving operational reliability.

[0018] Furthermore, a fault detection routine can be implemented to perform a plausibility check, particularly during operation, based on the measured temperature difference(s), in order to identify malfunctions. For example, in a heating circuit, a significantly higher temperature in the return line (i.e., after the consumers) compared to the flow temperature during the heating phase is implausible. Therefore, a malfunction would be detected above a certain threshold (e.g., the ratio of flow temperature to return temperature). This further improves operational reliability.

[0019] It is advantageous to include an error output that can indicate a malfunction visually and / or audibly. This allows for easy notification of errors or incorrect installations to the installation personnel. For example, the error can be displayed via a screen, a speaker, a light (flasher, LED, etc.), or transmitted to the intended recipient via a message, such as a wireless readout device, a smartphone, a smart home control system, or the utility company's control center. Transmission can also occur via Bluetooth, infrared, IoT (Internet of Things) applications, NFC (Near Field Communication), cellular networks, ISM (Industrial, Scientific and Medical Band), SRD (Short Range Devices), SMS (Short Message Service), in connection with big data processing, or similar methods.

[0020] In the alternatively claimed method for operating a fluid meter, in particular a heat meter for measuring the amount of heat and / or cold in a fluid, the fluid meter is generally operated in a fluid piping system with a supply and a return line. Advantageously, the fluid meter can be installed either in the supply or return line of the fluid piping system. The fluid meter comprises a connection housing, a measuring arrangement for determining the flow rate, a control and evaluation unit, and a first and a second temperature sensor.

[0021] The first and second temperature sensors are designed to determine the flow and return temperatures, respectively. Furthermore, the temperature of the fluid meter's connection housing is determined by calculating the temperature difference between this housing and at least one of the temperatures measured by the first and second temperature sensors. The assignment of the first and second temperature sensors to determine the flow or return temperature is based on this temperature difference. According to the invention, the temperature of the fluid meter's connection housing is determined using the flow rate measurement setup. Description of the invention using exemplary embodiments

[0022] Advantageous embodiments of the present invention are explained in more detail below with reference to the drawing figures. These show: Fig. 1 a highly simplified schematic representation of a heat quantity meter according to the invention within a fluid piping system, as well as Fig. 2 a highly simplified schematic representation of an embodiment of the heat quantity meter according to the invention.

[0023] In Fig. Figure 1 shows the basic installation situation of a fluid meter according to the invention in a fluid piping system. The fluid meter is designed as a heat meter 1, which serves to measure the amount of heat and / or cold in the flowing fluid. The fluid piping system comprises a supply line 20 and a return line 21, wherein one or more consumers (not shown) can be installed between the supply line 20 and the return line 21, which are supplied with heat and / or cold by the fluid piping system (e.g., hot water supply, cooling system, or the like). The direction of fluid flow is indicated by arrows in the figures.

[0024] The heat meter 1 includes a connection housing 2, by means of which it can be installed in the fluid piping system. For this purpose, the connection housing 2 includes an inlet 2a and an outlet 2b, which are configured, for example, as in Fig. As shown in Figure 1, each has a flanged connection for connection to corresponding flanged connections 22, 23 of the fluid piping system. Alternatively, other connection devices known from the prior art, e.g., threaded connections, may also be provided. The heat meter 1 can optionally be installed in the flow line 20 or, as shown in Figure 1, in the fluid piping system. Fig. 1 shown, to be installed in the return line 21 of the fluid piping system.

[0025] The heat meter 1 also has two temperature sensors 4, 5, each arranged in the supply line 20 or return line 21 of the fluid piping system. Temperature sensor 4 is connected to the supply line 20 via a connection device 6, and temperature sensor 5 is connected to the return line 21 via a connection device 7. The connection device 6, 7 can be, for example, a thermowell or screw-in sleeve, which brings the temperature sensors 4, 5 into thermal contact with the fluid without the temperature sensors 4, 5 coming into contact with the fluid itself. The thermowells are preferably oriented against the flow direction of the fluid. Any type of temperature sensor known from the prior art can be used as the temperature sensors 4, 5, such as a PT-100, thermocouple, or the like.

[0026] In Fig.Figure 2 shows a simplified embodiment of the heat meter 1 according to the invention. The heat meter 1 comprises a control and evaluation unit 3 and, as a measuring arrangement for determining the flow rate, an ultrasonic measuring arrangement comprising two ultrasonic transducers 8, 9 and two deflection devices 11, 12. The ultrasonic waves generated by the ultrasonic transducers 8, 9, so-called ultrasonic bursts or ultrasonic signals, travel along an ultrasonic measuring section 10 located between the ultrasonic transducers 8, 9. The deflection devices 11, 12 are designed to deflect the ultrasonic waves such that the ultrasonic measuring section 10 runs in a U-shape through the connection housing 2. However, embodiments of the fluid meter according to the invention in which the ultrasonic measuring section 10 runs, for example, straight or with multiple deflections through the connection housing 2 are also expressly included.

[0027] Furthermore, the temperature of the connection housing of heat meter 1 is determined. This temperature essentially corresponds to the fluid temperature at the installation location (supply or return) of the connection housing of heat meter 1. An ultrasonic measuring arrangement for flow rate determination is provided as a means of determining the temperature of heat meter 1. For this purpose, a temperature difference between the temperature of the connection housing of heat meter 1 and at least one of the temperatures of the first and second temperature sensors 4, 5 is determined. Based on the determined temperature difference(s), it is then determined which of the temperature sensors 4, 5 is installed in the supply line 20 and which in the return line 21 by selecting the temperature sensor 4, 5 whose temperature has a smaller temperature difference to the temperature of heat meter 1, i.e., the installation location of heat meter 1.The flow is assigned to either the supply line (20) or the return line (21). This assignment can be made either during the initial installation of the heat meter 1 or at predefined intervals during operation. This allows incorrect installations and configurations to be corrected retroactively without additional modifications.

[0028] Advantageously, the heat meter 1 includes a power supply (not shown for clarity). This power supply can be, for example, a battery, in particular a lithium battery (e.g., an A-cell or a D-cell with a lifespan of more than 10 years), or a power supply unit (e.g., 24 V or 230 V). Furthermore, a communication module (not shown) can also be provided, enabling the heat meter 1 to communicate with a higher-level unit, such as a data logger, via radio, L-Bus, M-Bus, RS-232, RS-458, LAN, or similar means, for example, to transmit operating or consumption data.

[0029] The disclosure explicitly includes combinations of individual features (sub-combinations) as well as possible combinations of individual features of different forms not shown in the drawings. REFERENCE MARK LIST 1 heat meter 2 connection housings 2a Entrance 2b Outlet 3 Control and evaluation unit 4 first temperature sensor 5 second temperature sensor 6 Connection device 7 Connection device 8 ultrasound transducers 9 ultrasound transducers 10 Ultrasonic measuring section 11 Deflection device 12 Deflection device 13 Error output 20 lead time 21 Return 22 Flange connection 23 Flange connection

Claims

[1] Fluid meter, namely heat meter (1) for recording the quantity of cold and / or heat of a fluid, for installation in a supply (20) or return (21) of a fluid piping system, comprising - a connection housing (2), - a measuring arrangement for determining flow rates, - a control and evaluation unit (3) as well as - a first temperature sensor (4), which is intended for installation in the flow line (20) and is intended there for determining the temperature in the flow line (20), - a second temperature sensor (5) which is intended for installation in the return line (21) and is intended there for determining the temperature in the return line (21), - wherein a means for determining the temperature of the connection housing (2) of the fluid meter is provided, - wherein a temperature difference between the temperature of the connection housing (2) of the fluid meter and at least one of the temperatures of the first (4) and second temperature sensor (5) can be determined, wherein the control and evaluation unit (3) determines, on the basis of the determined temperature difference between the temperature of the fluid meter and at least one of the temperatures of the first and second temperature sensors (4, 5), which of the temperature sensors (4, 5) is installed in the supply line (20) or return line (21), wherein the measuring arrangement for determining the flow rate is provided as a means for determining the temperature of the connection housing (2) of the fluid meter, where the temperature sensors (4, 5) are automatically assigned to the flow (20) or return (21), wherein the temperature of the connection housing (2) of the fluid meter is determined on the basis of a temperature-dependent transit time of an ultrasonic signal in the fluid, and wherein a look-up table is provided in which the transit times of the ultrasonic signal in the fluid are stored as a function of the corresponding temperature of the fluid and / or the connection housing (2) of the fluid meter and the temperature to be determined of the connection housing (2) of the fluid meter can be derived from the transit time of the ultrasonic signal and the look-up table. [2] Fluid counter according to claim 1, characterized by , that the measuring arrangement for determining the flow rate comprises at least one ultrasonic transducer (8, 9) and one ultrasonic measuring section (10). [3] Fluid meter according to at least one of the preceding claims, characterized by , that the temperature sensor (4, 5) whose temperature has a smaller temperature difference to the temperature of the fluid meter is assigned to the installation location of the fluid meter. [4] Fluid meter according to at least one of the preceding claims, characterized by, that the temperature sensors (4, 5) are arranged such that either the temperature of the first (4) or the second temperature sensor (5) corresponds at least substantially to the temperature of the fluid meter. [5] Fluid meter according to at least one of the preceding claims, characterized by , that a malfunction is detected if the temperature of the temperature sensor (4, 5) assigned to the installation location of the fluid meter differs significantly from the temperature of the fluid meter. [6] Fluid meter according to at least one of the preceding claims, characterized by , that an error routine is provided, whereby a plausibility check is carried out based on the determined temperature difference(s), which is used to determine malfunctions. [7] Fluid meter according to at least one of the preceding claims, characterized by, that an error output (13) is provided which is designed to output malfunctions visually and / or audibly. [8] Method for operating a fluid meter, namely a heat meter (1) for recording the quantity of cold and / or heat of a fluid, wherein the fluid meter is operated in a fluid piping system with a supply (20) and a return (21), and the fluid meter - a connection housing (2) - a measuring arrangement for determining flow rates, - a control and evaluation unit (3) as well as - comprises a first temperature sensor (4), wherein the first temperature sensor (4) is intended for determining a flow temperature, and - comprises a second temperature sensor (5), wherein the second temperature sensor (5) is intended for determining a return temperature, wherein the temperature of the connection housing (2) of the fluid meter is determined, and wherein a temperature difference is determined between the temperature of the connection housing (2) of the fluid meter and at least one of the temperatures of the first and second temperature sensors (4, 5), wherein the first and second temperature sensors (4, 5) are assigned to determine the flow temperature or the return temperature based on the temperature difference between the temperature of the connection housing (2) of the fluid meter and at least one of the temperatures of the first and second temperature sensors (4, 5), wherein the temperature of the connection housing (2) of the fluid meter is determined using the measuring arrangement for determining the flow rate, where the temperature sensors (4, 5) are automatically assigned to the flow (20) or return (21), wherein the temperature of the connection housing (2) of the fluid meter is determined on the basis of a temperature-dependent transit time of an ultrasonic signal in the fluid, and wherein a look-up table is provided in which the transit times of the ultrasonic signal in the fluid are stored as a function of the corresponding temperature of the fluid and / or the connection housing (2) of the fluid meter and the temperature to be determined of the connection housing (2) of the fluid meter can be derived from the transit time of the ultrasonic signal and the look-up table.

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