DEVICE AND METHOD FOR DETECTING CHANGES IN THE VALUE OF A PHYSICAL QUANTITY

Description

[0001] The invention relates to a device for detecting changes in the value of a physical quantity. Furthermore, the invention relates to a detection system, a method for detecting changes in the value of a physical quantity, the use of a device, and a computer program product.

[0002] In pipeline networks, such as those used for drinking water supply, there is a risk of pipe bursts due to pressure surges caused by fluid dynamics. This problem occurs relatively frequently, so drinking water suppliers have a particular interest in detecting pressure surge events and, in particular, locating a potential pipe burst.

[0003] To prevent pressure surges or at least reduce their intensity, it is known to use so-called mechanical water hammer arrestors at various points in the pipeline network. For example, DE 617 502 C and EP 0 507 705 A1 disclose such devices. While the water hammer arrestors can dampen pressure surges, they cannot provide information about the pressure surge events.

[0004] To limit the damaging effects of pressure surges, pre-calculated parameters regarding material selection and pipe wall thickness can be considered during the planning and construction of pipeline networks to prevent pipe bursts. However, this approach is not practical in most cases, especially since aging processes such as corrosion are not taken into account.

[0005] It is also possible to distribute pressure sensors throughout the pipeline network to continuously monitor pressure levels. However, the continuous pressure measurement required necessitates an adequate power supply for each measuring point. Given the considerable length of pipeline networks (especially in drinking water supply systems), this entails significant energy and material costs. Furthermore, a distributed sensor network is only practical if the sensors are wireless. Continuous pressure measurement also consumes a relatively large amount of energy, which in turn significantly reduces battery life.

[0006] In DE 7 040 823 U and in DE 6 911 897 U, a pressure switch with switching point setting for detecting a pressure value of a fluid is disclosed.

[0007] DE 582 011 A discloses a pressure switch which closes an electrical contact when a certain pressure threshold of a fluid is exceeded, for example to interrupt the cooling process of a refrigerator.

[0008] EP 3 588 042 A1 discloses a pressure element for monitoring a fluid acting upon it. The pressure element is designed to close an electrical circuit in response to a change in the pressure exerted on it by the fluid, regardless of the absolute pressure value. This electrical circuit then acts as a trigger for a downstream pressure sensor. However, the pressure element is only suitable for detecting relatively large pressure changes.

[0009] DE 10 2005 023692 B3 discloses a pressure sensor group with two pressure sensors and a leak monitoring computer.

[0010] The invention is based on the objective of enabling the detection of changes in the value of a physical quantity in a way that allows for high accuracy while simultaneously requiring little energy.

[0011] This problem is solved by a device for detecting changes in the value of a physical quantity according to claim 1. Furthermore, the problem is solved by a pipeline through which a fluid can flow, according to claim 7. In addition, the problem is solved by a detection system according to claim 9. Furthermore, the problem is solved by a method for detecting changes in the value of a physical quantity according to claim 10. Finally, the problem is solved by using a device according to claim 12 and a computer program product according to claim 13. Advantageous embodiments are described in the dependent claims.

[0012] A device according to the invention for detecting changes in the value of a physical quantity comprises the following parts: a first component configured to generate a first output signal when a threshold value of the rate of change of the value of the physical quantity is exceeded, a second component configured to determine the value of the physical quantity and generate a corresponding second output signal, and a control unit comprising a microprocessor configured to execute predefined instructions, a memory, and a power supply configured to provide energy to the second component, wherein the control unit is connected to the first component and the second component either by cable or wirelessly and is configured to read out the first output signal and the second output signal.

[0013] The control unit is designed to acquire the value of the physical quantity at an adjustable measurement rate by supplying energy to the second component according to the intended measurement rate. Furthermore, the control unit is designed to store the value acquired via the second output signal in its own memory. In addition, upon receiving the first output signal, the control unit is designed to immediately supply energy to the second component, regardless of the currently intended measurement rate, in order to acquire a current value of the physical quantity via the second output signal and store it in its memory.The term "current value" means that it doesn't just need to be determined at a single point in time, but also over a defined period of time – for example, until the threshold exceedance criterion no longer applies. Therefore, the "current value" can also, in the truest sense, be a trend in value.

[0014] The device according to the invention can advantageously determine a current, absolute measured value of the physical quantity via the second component at a predetermined measurement rate and store it in a memory for further processing. This (absolute) measurement can be performed particularly energy-efficiently if a low measurement rate (in measurements per unit of time) is selected and if the second component is not supplied with energy during the measurement pause. A slow decrease or increase in the physical quantity can thus be reliably detected with low energy consumption.

[0015] For the detection of relatively rapid changes in the physical quantity, the sole use of the second component may be insufficient, as the measurement of the physical quantity may be too imprecise in terms of timing due to a relatively high predefined measurement rate; that is, the measurement rate may be chosen too low. The control unit of the device according to the invention is therefore connected to a further component (the first component), which is configured to generate a first output signal when a threshold value of the rate of change of the value of the physical quantity is exceeded. In other words, the first component is able to detect a relative change in the physical quantity directly, i.e., without requiring a subsequent calculation of difference values, and consequently forward a signal to the control unit.In response to the signal received by the first component, the control unit can immediately supply energy to the second component in order to acquire a current value of the physical quantity (earlier than intended by the predetermined measurement rate). The first component therefore serves to detect relatively rapid changes in the physical quantity.

[0016] The device according to the invention advantageously combines a temporally finely resolved detection of a value of a physical quantity with minimal energy expenditure.

[0017] The control unit is designed to adjust the measurement rate when a threshold is exceeded by the rate of change of previously recorded values ​​of the physical quantity stored in its memory. In other words, the control unit adjusts the rate of change based on the rate of change of the historical values ​​of the physical quantity stored in its memory when a threshold is exceeded. The current rate of change can advantageously be determined by the control unit itself using suitable algorithms and compared with the threshold. However, it is also possible for an external, outsourced processing unit to perform this task and, if necessary, alert the control unit when the threshold is exceeded.For example, if a high current rate of change is detected, the control unit can increase the measurement rate in order to resolve the physical quantity more accurately in time, which may allow certain characteristics of the physical quantity to be better identified.

[0018] In an advantageous further development of the invention, the device is designed to transmit the values ​​of the physical quantity stored in the memory to a higher-level evaluation unit at predetermined times and / or on request, in particular to a cloud-based evaluation unit.

[0019] The first component can be configured to generate an electrical voltage as the first output signal when the rate of change of the physical quantity exceeds a threshold due to a force exerted on the first component by that physical quantity. This voltage can then be used as the input signal for special trigger electronics, which generate a trigger signal and transmit it to the control unit. The trigger signal can then initiate a hardware interrupt in the control unit, thus informing it that the threshold has been exceeded.

[0020] In an advantageous embodiment of the invention, the threshold value of the rate of change of the physical quantity is five bar per second, wherein the physical quantity represents pressure, in particular the pressure of a fluid in a pipeline. The first component can advantageously be ring-shaped. The first component can preferably comprise a material that behaves according to the piezoelectric effect, which reacts to the application of a force caused by the pressure change by generating an electrical voltage. Such a material is ferroelectric and exhibits a permanent electric dipole.

[0021] The second component advantageously represents a pressure sensor, which serves to detect pressure as a physical value.

[0022] In addition to detecting pressure changes, the control unit can provide an exact timestamp of the change event and may include sensors for measuring temperature, humidity, vibration, brightness, and the like.

[0023] The previously described problem is also solved by a pipeline. This pipeline is permeable to a fluid and includes at least one device as previously described. The device is arranged in the pipeline such that the first component can detect the rate of change of the fluid pressure, and the second component can detect the value of the fluid pressure in the pipeline. With this pipeline, it is particularly advantageous to detect changes in the fluid pressure, allowing appropriate measures to be taken to counteract the pressure change. Preferably, the pipeline has a plurality of such devices as described above. This enables the pressure change to be detected with local resolution, allowing for more efficient and faster implementation of any necessary countermeasures.

[0024] The task is also solved by a detection system which comprises a multitude of devices as previously explained, which are connected to one or more higher-level evaluation units, the devices preferably being arranged in a pipeline.

[0025] The previously explained task is further enhanced by a method for detecting changes in the value of a physical quantity using a device comprising: a first component which is configured to generate a first output signal when a threshold value of a change rate of the value of the physical quantity is exceeded, a second component which is configured to determine the value of the physical quantity and to generate a corresponding second output signal, a control unit which has a microprocessor which is configured to execute predefined instructions, a memory and a power supply which is configured to supply the second component with energy, wherein the control unit is connected to the first component and the second component by cable or wirelessly and is configured accordingly, solved.

[0026] The process includes the following steps: Acquiring the value of the physical quantity at a measurement rate specified by the control unit, by the control unit supplying the second component with energy according to the specified measurement rate and storing the value acquired via the second output signal generated by the second component in the memory of the control unit, in response to receiving a first output signal generated by the first component when the threshold of the rate of change of the value of the physical quantity is exceeded, immediately and independently of the currently intended measurement rate, supplying the second component with energy in order to acquire a current value of the physical quantity via the second output signal and to store it in the memory of the control unit.The term "a current value" means that this value must not only be determined at a single point in time, but also over a defined period of time – for example, until the criterion of exceeding the threshold has ceased to apply.

[0027] The measurement rate is adjusted by the control unit when a threshold value of a change rate of previously recorded and stored values ​​of the physical quantity is exceeded.

[0028] The physical quantity values ​​stored in the memory can be transmitted by the control unit to a higher-level evaluation unit, particularly a cloud-based evaluation unit, at predefined times and / or on request. The "Narrowband IoT" standard, for example, can be used for this purpose.

[0029] The problem is also solved by using a device as previously explained, preferably a plurality of such devices, to monitor a fluid-filled pipeline.

[0030] Furthermore, the problem is solved by a computer program product according to claim 13.

[0031] The properties, features, and advantages of this invention described above, as well as the manner in which they are achieved, will become clearer and more readily understandable in connection with the following description of the exemplary embodiments, which are explained in more detail in conjunction with the figures. The figures show: FIG 1 shows a diagram of a device according to the invention; and FIG 2 shows a time course of a pressure of a fluid measured in a pipeline.

[0032] FIG 1 Figure 1 shows a diagram of a device 1 according to the invention. The device 1 comprises a control unit 2, a first component 3, a second component 4 and a trigger electronics 6.

[0033] The first component 3 is ring-shaped and made of a material that responds to a mechanical force with an electrical voltage according to the piezoelectric effect. The piezoelectric voltage generated as a first output signal 7 is directly proportional to a pressure change, for example, of a fluid flowing through a pipe and exerting pressure on the first component 3 and the second component 4. The second component 4 includes a pressure sensor that can be used, among other things, to determine the pressure of the fluid flowing through the pipe (not shown). The first component 3 can be arranged directly adjacent to the second component 4.

[0034] The piezoelectric voltage, as the first output signal 7, is fed into the trigger electronics 6 such that when a certain pressure change threshold of the fluid is exceeded, a sufficiently high piezoelectric voltage 7 is applied to the trigger electronics 6 to generate a trigger signal 8, which is fed into the control unit 2. In the control unit, the trigger signal 8 triggers a hardware interrupt, thereby informing the control unit 2 of the event of the pressure change exceeding the threshold.

[0035] The trigger electronics 6 can, for example, include a low-pass filter and a Schmitt trigger to provide the described functionalities. The current consumption of the trigger unit can be 3.6 microamperes. The first component can, for example, detect rapid pressure transients with a change rate of 5 bar per second or higher, with the generated piezoelectric voltage 7 being, for example, 20 millivolts.

[0036] The control unit 2 comprises a microprocessor 9, which is configured to execute predefined instructions, a memory 10, and a power supply 5, which is configured to supply energy to the second component 4. The control unit 2 is connected to both the first component 3 and the second component 4, either via a cable or wirelessly, and is configured to read the first output signal 7 and a second output signal 11 generated by the second component 4.

[0037] The control unit 2 is also designed to acquire the pressure value measured by the second component 4 at an adjustable measurement rate. This is achieved by the control unit 2 supplying the second component 4 with energy via the power supply 5 according to the intended measurement rate and storing the pressure value acquired via the second output signal 11 in the memory 10 of the control unit 2. The measurement rate can, for example, be one measurement every two seconds. During the measurement pauses, the pressure sensor (the second component 4) is completely de-energized, and the microcontroller 9 operates in an energy-saving low-power mode. Each pressure measurement can, for example, take seven milliseconds.

[0038] The microcontroller 9 of control unit 2 contains an algorithm that checks the historical pressure values ​​stored in memory 10 to see if a threshold for the rate of change of the historical pressure values—in other words, the difference between a current and a previous pressure value—has been exceeded. If this threshold is exceeded, the algorithm is configured to adjust the measurement rate. For example, if the measured pressure drops rapidly, the algorithm will increase the measurement rate to capture and store the pressure values ​​in memory 10 with greater temporal resolution. This increase in the measurement rate can be gradual, i.e., in small increments, to avoid excessive energy consumption.

[0039] The control unit 2 is further configured to immediately supply the second component 4 with energy upon receiving the first output signal 7, regardless of the currently intended measurement rate, in order to acquire a current pressure profile at a high measurement rate via the second output signal 11 and store it in the memory 10. Thus, in the case of large, rapid pressure changes, the control unit 2 can react virtually instantly, whereas a purely software-based adjustment of the measurement rate would be delayed.

[0040] FIG 2This shows exemplary pressure profiles of a fluid in a pipeline over time. A first curve, I, represents an actual initial pressure profile. The previously described control unit 2 specifies a measurement rate of one measurement every two seconds, symbolized by the cross markings in curve I. By comparing the pressure value measured after eight seconds with a pressure value measured at six seconds, the algorithm of control unit 2 determines that a certain pressure change threshold has been exceeded. It then increases the measurement rate to capture the (subsequent) pressure profile more closely over time and thereby confirm a possible trigger event with further pressure measurements. The increase in the measurement rate can be gradual in several stages (e.g.,2s, 500ms, 100ms, 10ms), in order to detect a significant pressure gradient as quickly as possible and to detect it as a software-based trigger event and trigger a software trigger.

[0041] However, the pressure gradient may be so weak in the further course that the trigger criterion (a defined pressure change must be present for a certain period of time, i.e., the product pressure gradient [bar / s] * duration [s], i.e., dp / dt * T) is not met, with the result that no software trigger is activated and the measurement rate is reset to the slowest measurement rate, e.g., 2s.

[0042] The software trigger instructs microcontroller 9 to increase the sampling rate for a specific, predefined duration, e.g., 60 seconds (e.g., to 10 ms), in order to capture the subsequent pressure profile at a high sampling rate. The high sampling rate is necessary to achieve the best possible spatial resolution when cross-correlating with the signal profiles from neighboring measuring points.

[0043] The adaptive increase in the measurement rate serves to provide the software trigger with further measured values ​​as quickly as possible in order to check or reject the defined trigger criterion. The product "pressure gradient * duration" (e.g., 0.1 bar / s * 3 s = 0.3 bar) can be used as the trigger criterion. The criterion is also met if the gradient is larger but of shorter duration (e.g., 0.3 bar / s * 1 s). Short outliers in the measured values ​​(e.g., interference signals) do not immediately lead to a false trigger.

[0044] One advantage of the invention arises, for example, when a non-critical pressure fluctuation occurs in a water network (e.g., due to a sudden high water consumption by users). In this case, the pressure in the pipe would rise again to its original value (above the threshold). Due to the fine measurement resolution of the device 1 according to the invention, this rise could be detected quickly, and the event could be correctly classified as non-critical.

[0045] A second curve II shows a second pressure value profile II, which exhibits a sharp drop after approximately four seconds. If the device 1 were designed solely to perform a purely software-based adjustment of the measurement rate via the algorithm, the algorithm would only detect the pressure drop after six seconds due to the two-second measurement interval and would then increase the measurement rate (in region B). However, the device 1 according to the invention uses the trigger from the first component 1 to increase the measurement rate in region A, i.e., as soon as the pressure drop occurs (e.g., to 10 ms). This allows the profile of curve II between regions A and B to be recorded precisely, unlike previously known devices.

[0046] The described device 1 enables energy-efficient and simultaneously speed-adaptive detection of pressure changes in a fluid within a pipeline. Using the proposed device 1 and its reduced data and energy requirements, pipe break detection with battery-powered sensors can be performed for many years. Furthermore, precise leak localization is possible through cross-correlation (raw pressure data), which is selectively acquired at the time of the pressure drop.

Claims

1. Apparatus (1) for detecting changes in a value of a physical variable in a pipeline network, comprising: - a first component (3) which is designed so as to generate a first output signal (7) when a threshold value of a rate of change of the value of the physical variable is exceeded, - a second component (4) which is designed so as to determine the value of the physical variable and to generate a corresponding second output signal (11), - a control unit (2) which has a microprocessor (9) that is designed so as to process predefined commands, a memory (10) and an energy supply (5) which is designed so as to supply the second component (4) with energy, wherein the control unit (2) is connected to the first component (3) and the second component (4) by cable or wirelessly and is designed to read out the first output signal (7) and the second output signal (11), wherein the control unit (2) is designed so as to detect the value of the physical variable at a customisable measurement rate, in that the control unit (2) supplies the second component (3) with energy in accordance with the specified measurement rate, and to store the value which is detected via the second output signal (11) in the memory (10) of the control unit (2) in each case, characterised in that the control unit (2) is designed so as to supply the second component (4) with energy immediately in response to receiving the first output signal (7) and regardless of the presently specified measurement rate, in order to detect a present value of the physical variable via the second output signal (11) and store it in the memory (10), and that the control unit (2) is designed so as to adjust the measurement rate when a threshold value of a rate of change of previously detected values of the physical variable stored in the memory (10) is exceeded.

2. Apparatus (1) according to claim 1, which is designed so as to transfer the values of the physical variable stored in the memory (10) to a higher-level evaluation unit at predefined points in time and / or on request, in particular to a cloud-based evaluation unit.

3. Apparatus (1) according to one of the preceding claims, wherein the first component is designed so as to generate an electrical voltage as the first output signal (7) when the threshold value of the rate of change of the value of the physical variable is exceeded due to an effect of force applied to the first component (3) by the physical variable.

4. Apparatus (1) according to claim 3, wherein the threshold value of the rate of change of the value of the physical variable is five bar per second, wherein the physical variable represents a pressure, in particular a pressure of a fluid in a pipeline.

5. Apparatus (1) according to claim 3 and 4, wherein the first component (3) is ring-shaped.

6. Apparatus (1) according to one of the preceding claims, wherein the second component (4) is a pressure sensor for detecting a pressure as a physical value.

7. Pipeline through which a fluid can flow and which has at least one apparatus (1) according to one of claims 1 to 6, wherein the apparatus (1) is arranged in the pipeline in such a way that the first component (3) can detect a rate of change of a pressure of the fluid and the second component (4) can detect the value of the pressure of the fluid in the pipeline.

8. Pipeline according to claim 7, which has a plurality of apparatuses (1) according to one of claims 1 to 6.

9. Detection system, comprising a plurality of apparatuses (1) according to one of claims 1 to 6, which are connected to one or more higher-level evaluation units, wherein the apparatuses (1) are preferably arranged in a pipeline according to claim 8 or 9.

10. Method for detecting, in a pipeline network, changes in a value of a physical variable using an apparatus (1), the apparatus (1) comprising: - a first component (3) which is designed so as to generate a first output signal (7) when a threshold value of a rate of change of the value of the physical variable is exceeded, - a second component (4) which is designed so as to determine the value of the physical variable and to generate a corresponding second output signal (11), - a control unit (2) which has a microprocessor (9) that is designed so as to process predefined commands, a memory (10) and an energy supply (5) which is designed so as to supply the second component (4) with energy, wherein the control unit (2) is connected to the first component (3) and the second component (4) by cable or wirelessly and is designed for this purpose, the method comprising: - detecting the value of the physical variable at a measurement rate specified by the control unit (2), in that the control unit (2) supplies the second component (4) with energy in accordance with the specified measurement rate and stores the value which is detected via the second output signal (11) that is generated by the second component (4) in the memory (10) of the control unit (2) in each case, - in response to receiving a first output signal (7) that is generated by the first component (3) when the threshold value of the rate of change of the value of the physical variable is exceeded, immediately and regardless of the presently specified measurement rate, supplying the second component (4) with energy in order to detect a present value of the physical variable via the second output signal (11) and to store it in the memory of the control unit (2), - the control unit (2) adjusting the measurement rate when a threshold value of a rate of change of previously detected values of the physical variable stored in the memory (10) is exceeded.

11. Method according to claim 10, wherein the values of the physical variable stored in the memory (10) can be transferred from the control unit (2) to a higher-level evaluation unit at predefined points in time and / or on request, in particular to a cloud-based evaluation unit.

12. Use of at least one apparatus (1) according to one of claims 1 to 6, preferably of a plurality of such apparatuses (1), to monitor a pipeline through which fluid flows.

13. Computer program product, comprising commands which cause the control unit (2) in one of claims 10 or 11 to perform the steps in one of claims 10 or 11.