Valve arrangement for controlling fluid flow

Abstract

A valve arrangement for controlling fluid flow. The valve arrangement includes a valve plug located within a valve body, an actuator operably connected or connectable to the valve plug for moving the valve plug to regulate a flow rate through the valve body, a differential pressure regulator configured to limit a differential pressure change on the valve plug when fluid flows through the valve body, a flow meter configured to measure a flow rate through the valve body, and a control unit. The control unit is configured to receive a request input signal representative of a desired flow rate through the valve body and a flow input signal from the flow meter representative of a measured flow rate. The control unit is configured to send a control signal to the actuator based on the received signal to move the valve plug or hold the valve plug in its position.

Description

Technical Field

[0001] The present application relates to a valve arrangement for controlling the flow of a fluid. Background Art

[0002] Fluid distribution systems used, for example, for heating, cooling, and supplying water are designed to supply fluid from a source to a point of consumption. Each point of consumption typically has a calculated and designed flow or differential pressure requirement. However, depending on the type of hydronic system, the flow requirements are often time-variable and can change with factors such as seasonality (e.g., summer or winter) of changing loads from the point of consumption, temperature changes of the system fluid, changes in the consumption of the system fluid (e.g., for potable water).

[0003] Control valves are often used in fluid distribution systems and have a variable opening so that the flow rate can be controlled. Thereby, the flow rate supplied to the consumption point can be varied in an efficient manner. However, due to variations in the differential pressure across the control valve, distortions of the controlled flow rate may occur. In order to reduce the risk of such distortions, control valves have been combined with differential pressure regulators to keep the differential pressure variations within acceptable levels. Such combinations are often referred to as "pressure independent control valves". The idea behind such combinations is that a certain setting on the control valve (or on the actuator controlling the control valve) is expected to result in a corresponding flow rate regardless of the pressure variations in the system, since such pressure variations should be handled by the differential pressure regulator to keep the differential pressure across the control valve substantially constant. Although these combinations are referred to as "pressure independent", there will still be some variations in the differential pressure, for example up to ±20% (due to the so-called P-band of the differential pressure regulator).

[0004] The above-mentioned pressure-independent control valves require a minimum differential pressure (the so-called "starting pressure") to operate properly. This starting pressure increases the size of the pump head of the fluid distribution system and thus also increases the operating cost. Conversely, if the system cannot provide the required starting pressure, pressure changes at low starting pressures will result in inaccurate flow control. SUMMARY OF THE INVENTION

[0006] The object of the inventive concept is to at least partially alleviate the above mentioned disadvantages of the prior art. This object and other objects which will become apparent from the following disclosure are achieved by the valve arrangement set forth in the independent claims. Some non-limiting exemplary embodiments are presented in the dependent claims.

[0007] The inventive concept is based on the recognition that by measuring the flow rate of a valve arrangement with a differential pressure regulator and controlling the degree of opening of a control valve based on such flow measurement, accurate flow control can be achieved even at very low differential pressures across the control valve. Furthermore, the error margin at high differential pressures can also be reduced. The general inventive concept and some exemplary embodiments are discussed further below.

[0008] According to an aspect of the present disclosure, a valve arrangement for controlling fluid flow is provided. The valve arrangement comprises:

[0009] a valve body having an inlet for receiving the fluid into the valve body and an outlet for discharging the fluid from the valve body,

[0010] a valve plug located in the valve body and movable between a closed position, in which a fluid flow from the inlet to the outlet is blocked, and a fully open position, in which only a leakage flow is allowed from the inlet to the outlet,

[0011] an actuator operatively connected or connectable to the valve plug for moving the valve plug to adjust the flow rate through the valve body,

[0012] a differential pressure regulator comprising a movable separating member having a first side in fluid communication with a fluid flow upstream of the valve plug and an oppositely facing second side in fluid communication with a fluid flow downstream of the valve plug, wherein the differential pressure regulator is configured such that the movable separating member is movable in response to a differential pressure between the first side and the second side, and such that movement of the movable separating member counteracts pressure changes on the valve plug when fluid flows through the valve body,

[0013] - a flow meter configured to measure a flow rate through the valve body,

[0014] - a control unit configured to receive:

[0015] i) a request input signal representing a desired flow rate through the valve body, and

[0016] ii) a flow input signal from a flow meter representing a measured flow rate,

[0017] The control unit is configured to send a control signal to the actuator based on the received request input signal and the received flow input signal to move the valve plug or keep the valve plug in its position.

[0018] By using a flow meter (notwithstanding the presence of a differential pressure regulator), and controlling the actuator based on the input signal received from the flow meter, accurate flow control through the valve body can be obtained even below the actuation pressure by directly controlling the input flow signal. This is possible as long as the differential pressure is sufficient to provide the flow required to open the valve plug more than the position where the valve plug would normally be located when the actuation pressure is obtained.

[0019] When the valve plug is not subjected to a moving force from the actuator, then the valve plug can be appropriately biased to remain in the closed position or the fully open position (i.e., the two end positions of the valve plug). Therefore, a spring member can be provided in the valve body, which provides a push or pull force to the valve plug so that the valve plug remains in one of its end positions. If the valve plug is in an open position between the end positions and it is desired to keep the valve plug in this position, then, depending on the type of actuator, it may be necessary to apply a control signal to the actuator to keep the valve in its position to counteract the force of the spring member.

[0020] Since the differential pressure regulator limits the change in differential pressure across the valve plug, there will not be any need for any selected actuator to perform a large stroke to compensate for the pressure change. Therefore, the selected actuator can have a relatively short stroke length and can therefore be reasonably relatively compact. Although the use of a small electric actuator can be considered, since the actuator typically has a transmission device for moving it step by step, controlling the movement of such an actuator may be considered to be less accurate. However, a small thermoelectric actuator can be used advantageously because the actuator is stepless and a higher accuracy can be obtained.

[0021] Therefore, according to at least one exemplary embodiment, the actuator is a thermoelectric actuator. Thermoelectric actuators are also beneficial because of their relatively low cost and because of their quiet operation. The thermoelectric actuator has a temperature sensing material that expands or contracts based on the temperature to which it is subjected. By operably connecting the valve stem carrying the valve plug to the temperature sensing material, the valve plug can follow the dimensional changes of the temperature sensing material. The thermoelectric actuator can be appropriately controlled by a PWM (pulse width modulation) signal. The PWM signal can be used to move the thermoelectric actuator in a specific direction or to keep the thermoelectric actuator in a fixed position. The technical benefits of using a thermoelectric actuator with PWM control in a valve arrangement can include: by changing the "power-on" time of the actuator, the speed of the actuator can be easily controlled. If it is desired to quickly move the valve plug from one open position to another open position, the power-on time can be significantly increased compared to the power-on time used to keep the valve plug in a steady-state position. If only a brief movement of the valve plug is desired, the power-on time can be only slightly changed.

[0022] It will be appreciated that while a PWM signal may be suitably used to control movement of an actuator or to maintain the position of an actuator (and hence movement of a valve plug or maintenance of a valve plug position), other types of control signals may be used, such as digital or analog control signals.

[0023] According to at least one exemplary embodiment, the control unit comprises an electronic memory or has access to an electronic memory, wherein the control unit is configured to determine a relationship between a change in the control signal and the effect of the change on the flow rate through the valve body based on data stored in the electronic memory, wherein the control unit is configured to control the actuator based on the relationship. If the actuator of the valve arrangement is a linear actuator, the control of the actuator is relatively simple because a differential pressure regulator is included. For a linear actuator (having a linear characteristic), for a certain change in the position of the actuator (e.g. in millimeters), you will get a certain change in the flow rate (e.g. in liters / hour). This will be independent of the current flow rate. Therefore, if the control unit receives a request for a certain change in the flow rate (such a request may, for example, come from a building management system BMS), the change will correspond to a certain position movement. However, for other types of actuators, such as thermoelectric actuators or 3-point actuators, such a simple linear relationship may not exist. For a 3-point actuator, the control unit will not know the position of the actuator because the actuator only moves in one direction or the other, depending on whether a positive voltage or a negative voltage is supplied to the actuator, respectively. In such a case where a simple linear characteristic is not available, the data stored in the electronic memory can be used to determine the relationship between a change in the control signal and the effect of that change on the flow rate. For example, an example can be provided regarding a thermoelectric actuator, in which the temperature sensing material expands or contracts based on the temperature to which it is subjected. Assume that the control unit is arranged to control the thermoelectric actuator so as to provide a steady state of 250 liters / hour through the valve body, and assume that in order to do this, the control unit controls the thermoelectric actuator to be powered at 0.5W so as to maintain the steady state (i.e., at this power, the temperature is such that the temperature sensing element neither contracts nor expands). If the control unit subsequently receives a request to change (e.g., to 350 liters / hour), it can determine based on the data stored in the electronic memory that the quickest way to achieve such a change is to increase the power significantly for a short period of time (e.g., to 1 W during 5 seconds), then to reduce the power slightly for a short period of time (e.g., to 0.7 W during 3 seconds), and then to return to 0.5W again. For another change, say to 470 liters / hour, the control unit may instead determine to increase to 1 W during 10 seconds, then decrease to 0.7 W within 3 seconds, and then return to 0.5 W again to maintain the new steady state. Thus, it can be understood from the above example that it may be more time-efficient to expand or contract the temperature sensing material at a relatively fast rate and then slow down as the target is reached, rather than providing power to slowly expand or contract the temperature sensing material to reach the target. Of course, the above figures are merely examples for ease of understanding and should in no way be considered as limitations of the present disclosure.The key is that the control unit has access to a "map", that is, data (e.g., power, time, position change, etc.) that can be used to calculate how a certain control signal change affects the flow rate, and how such a control signal can be changed to quickly achieve the desired change in flow rate.

[0024] Based on the above, it should be understood that the relationship between the control signal change and the flow rate can be a known and fixed relationship. This fixed relationship can be obtained from a lookup table. For linear characteristics, the fixed relationship can be obtained from a lookup table, or by calculation according to a predefined equation. In the example of a thermoelectric actuator, the lookup table may include a matrix in which, for example, power and time are mapped to their effects on the position of the thermoelectric actuator.

[0025] According to at least one exemplary embodiment, the control unit is configured to operate in a self-learning model by:

[0026] - after sending the control signal to the actuator, continuing to receive said flow input signal from the flow meter,

[0027] - determining the accuracy of said determined relationship between a change in the control signal and the effect on the flow rate, and

[0028] -updating said data in electronic storage based on the accuracy of said determination.

[0029] Thus, the correlation between future control signals and the impact on flow rate will be improved. This may be particularly advantageous for adapting control to different types of actuators and valves provided by different manufacturers. The control unit will learn from the flow meter how fast the desired flow rate is obtained, and can therefore adjust the control of the actuator to a specific connection for future position changes. For example, the actuator may initially move quickly to a position that roughly produces the desired flow rate, but due to the flow input signal, the control unit will want to compensate for any small errors. If such compensation causes self-oscillation due to the control unit trying to compensate back and forth, the self-learning model can be updated by a suitable algorithm and learned to identify and reduce such self-oscillations so as to reach or be very close to the desired flow rate. The self-learning model can, for example, be a machine learning model based on, for example, reinforcement learning, in which the model is rewarded or punished accordingly based on the quality / accuracy of the result and its relationship with the request input signal representing the desired flow rate.

[0030] According to at least one exemplary embodiment, the actuator is a proportional actuator, wherein a control signal from a control unit sets a position of the actuator, which in turn corresponds to a position of a valve plug, which in turn corresponds to an approximate flow rate through the valve body. The control signal may suitably be a digital control signal, however, it is conceivable to use an analog control signal.

[0031] Although the differential pressure regulator limits the variation of the differential pressure, as described above, there may still be considerable variation / tolerance. Such tolerances can be as high as ±20%, which is not uncommon for valves that are generally considered good in the art. Such large tolerances are not only due to variations in the differential pressure, but are also caused by inaccurate positioning of the actuator and by variations in the tolerances of the control valve. Therefore, according to this exemplary embodiment, when a new request input signal is received, the control unit can quickly control the actuator to move to a position that will approximately produce the desired flow rate. By then also taking into account the flow input signal, the control unit can then fine-tune the position of the actuator. Through this two-step procedure, a relatively quick arrival at the desired flow rate can be obtained regardless of any tolerances. This is reflected in the following exemplary embodiment.

[0032] Therefore, according to at least one exemplary embodiment, the control unit is configured to:

[0033] - based on the received request input signal, initially controlling the actuator to move to a position approximately corresponding to said desired flow rate, and subsequently,

[0034] - fine-tuning the position of the actuator in order to obtain a flow rate closer to a desired flow rate based on a received flow input signal representing a measured flow rate of the fluid after said initial control of the actuator.

[0035] This allows a flow rate value close to the desired flow rate to be quickly reached, after which fine adjustments can be made. This is a faster procedure than if the control unit were to compare the measured flow rate to the desired flow rate starting from a new requested flow input signal and make corrections and comparisons as the desired flow rate is slowly approached.

[0036] According to at least one exemplary embodiment, the control unit is configured to operate in a self-learning model by:

[0037] - using stored historical data representing control events, wherein fine-tuning is performed after the actuator has moved to a respective position approximately corresponding to a respective desired flow rate, and

[0038] - upon receiving a change in the desired flow rate via said request input signal, modifying the control signal based on said stored historical data to reduce the time required for subsequent fine-tuning to obtain the desired flow rate.

[0039] By considering the accuracy of the relationship between the control signal and the flow rate, the content of the control signal can be changed in response to future changes in the request input signal. Therefore, the control unit can improve the accuracy of the correlation between the control signal and the resulting flow rate, so that the initial resulting flow rate in the future is closer to the desired flow rate than it was historically, thereby reducing the time for subsequent fine-tuning.

[0040] The above two-step control by providing a control signal to obtain a flow rate at least close to the desired flow rate and then making fine adjustments by taking into account the measured flow rate and updating the control unit based on the self-learning model is beneficial because the control unit will improve its ability to predict the actuator position and / or flow rate for different control signal values. For electric actuators, such position prediction can, for example, reduce the number of movements that the actuator needs to perform, thereby increasing the actuator life.

[0041] Although the proportional actuator discussed above is convenient to use because it can provide a correlation between the control signal value and the approximate resulting flow rate, another type of actuator that can be advantageously used is an actuator that provides position feedback to the control unit. Therefore, according to at least one exemplary embodiment, the control unit is configured to receive position feedback from the actuator indicating the current position of the actuator, wherein the control signal from the control unit is based on the position feedback so as to move the actuator toward a desired position of the actuator, which in turn corresponds to a desired position of the valve plug, which in turn roughly corresponds to a desired flow rate through the valve body. This can be a suitable alternative to the above-mentioned proportional actuator. In this exemplary embodiment, the control unit can be configured only to move the actuator in the closing direction or the opening direction of the valve plug, and stop the actuator movement when the position feedback from the actuator informs the control unit that the actuator has reached the desired position, rather than having a correlation between the control signal and the actuator position (such as a certain voltage, for example, transitioning between 0V and 10V at a certain actuator position). The position feedback from the actuator can be provided, for example, by an integrated position sensor (such as an optical sensor, a magnetic sensor, a mechanical sensor, etc.).

[0042] Regardless of the type of actuator, such as the aforementioned thermoelectric actuator, proportional actuator, sensor integrated actuator, etc., the control unit may be suitably configured to detect signs of failure. This is at least partially reflected in at least one exemplary embodiment, according to which the control unit is configured to:

[0043] - continuing to receive the flow input signal from the flow meter after sending the control signal to the actuator for moving the actuator to the new position, and

[0044] - upon detecting that the flow rate measured by the flow meter deviates beyond a predefined permissible deviation, determining that a fault has occurred in the valve arrangement or in a pipe network connected to the valve arrangement. Such predefined permissible deviation may be suitably chosen to be large enough so that tolerances and normal error margins are not mistaken for a fault.

[0045] According to at least one exemplary embodiment, the control unit is configured to:

[0046] - When a fault is detected, a self-diagnostic program sequence is executed to identify which part of the valve arrangement has failed or to determine that the fault is in the pipe network to which the valve arrangement is connected.

[0047] The self-diagnostic program sequence may include controlling the actuator to move the valve plug between its closed position to its fully open position and taking into account how / whether the flow input signal changes. For example, in the case where the flow meter indicates the presence of flow even though the control unit has instructed the actuator via its control signal to move the valve plug to its closed position, this may indicate a malfunction of the actuator or the valve plug. On the other hand, if the expected change in the measured flow rate does not result when the valve plug is moved from its closed position to its fully open position, this may indicate a malfunction of the flow meter.

[0048] According to at least one exemplary embodiment, the valve arrangement further comprises one or more temperature sensors configured to measure a temperature in the fluid, wherein the control unit is configured to receive temperature information indicative of the temperature of the fluid from the one or more temperature sensors, wherein the control unit is configured to detect a failure of the flow meter based on the received temperature information and based on a received flow input signal from the flow meter.

[0049] This is advantageous because the temperature sensor should be able to determine whether there is flow if the flow meter does not detect any flow rate even when the actuator has moved the valve plug to the open state. If the temperature is changing when the valve is open, the control unit can interpret it as an inflow through the valve. Therefore, the control unit can then determine that the flow meter has failed. However, if the temperature does not change, it is more likely that there is no flow, in which case the possible fault originates from somewhere else in the pipe network. The control unit can also communicate with external devices (such as external circulation pumps and / or a central controller of a building management system (BMS)) as appropriate. For example, if the circulation pump is turned off, but the flow meter continues to give a positive flow input signal indicating a non-zero flow rate, the flow meter may fail. Although a single temperature sensor may be sufficient, using two or more temperature sensors for Δ (delta) temperature measurement can achieve even more accurate diagnosis. Δ temperature measurement can be performed by placing one temperature sensor upstream of a consumption point (such as a radiator) and another temperature sensor downstream of the consumption point. At high flow rates, the temperature difference (ΔT) across the consumption point will not be as high as at certain flow rates (at low flow rates, the fluid has more time to exchange heat at the consumption point). For example, by sending a control signal from the control unit to the actuator to change the valve plug position and thus the flow rate, a change in ΔT can be expected. If there is no such change, this may indicate, for example, a valve plug or actuator failure, or a communication failure between the control unit and the actuator.

[0050] According to at least one exemplary embodiment, when the request input signal indicates a desired flow rate equal to or below a predefined flow rate, the control unit is configured to ignore any flow input signal received from the flow meter and send a control signal based on the request input signal.

[0051] At very low flow rates, the accuracy of most commercially used flow meters is quite low. In fact, at very low flow rates, some flow meters may even be configured to stop measuring. For example, in one type of flow meter, a ball is caused to move back and forth (circulate) in a chamber by the flow flowing through the chamber, and the speed of the ball can be converted into a flow rate. However, at very low flow rates, the ball kinetic energy of the fluid will not be enough to move the ball. This inaccuracy in the flow meter at low flow rates may cause problems in the control algorithm used by the control unit. Therefore, when the control unit has determined that the request input signal indicates an expected flow rate value lower than a predefined flow rate, it can be a technical benefit for the control unit to ignore any flow input signal. Therefore, the predefined flow rate can be appropriately set based on the specifications of the flow meter used, for example, in the valve arrangement or based on its empirical testing.

[0052] According to at least one exemplary embodiment, the control unit is configured to periodically control the actuator to move the valve plug to an open position for which the resulting flow rate through the valve body is expected to have a magnitude measurable by a flow meter. This may be advantageous because the control unit can automatically confirm in this way whether the valve arrangement is considered to be working properly or a malfunction may have occurred. In the event that the control unit does not receive a flow input signal indicating an expected flow rate value, the control unit may be suitably configured to send an alarm signal to a building management system or to some other operably connected device (such as a remote server, a mobile phone, etc.). Such an alarm signal may be suitably sent in any other malfunction event discussed in the present disclosure.

[0053] In some exemplary embodiments, the control unit may be provided as a separate device that may be arranged to communicate wirelessly or wired with the flow meter and the actuator. However, in some exemplary embodiments, the control unit may be provided as an integrated part of the assembly. For example, the valve arrangement may include an actuator assembly that includes both the actuator and the control unit. Therefore, such an actuator assembly may be produced and delivered to a customer as one device that includes both the actuator and the integrated control unit. Similarly, in some exemplary embodiments, the valve arrangement may include a flow meter assembly that includes both the flow meter and the control unit. Therefore, such a flow meter assembly may be produced and delivered to a customer as one device that includes both the flow meter and the integrated control unit.

[0054] The control unit described herein may include a microprocessor, a microcontroller, a programmable digital signal processor, or another programmable device. The control unit may also or alternatively include an application specific integrated circuit, a programmable gate array or programmable array logic, a programmable logic device, or a digital signal processor. In the case where the control unit includes a programmable device such as the above-mentioned microprocessor, microcontroller, or programmable digital signal processor, the processor may also include a computer executable code that controls the operation of the programmable device.

[0055] The overall inventive concept can be implemented in conjunction with any suitable mechanical differential pressure regulator. For example, if the separation member is in the form of a piston, the movable separation member can be movable as a whole. In other examples, only a portion of the movable separation member can be movable, such as in the case of a membrane or diaphragm with a fixed peripheral portion but a movable central portion. These different examples are reflected in at least one exemplary embodiment, according to which the movable separation member is in the form of a membrane or a piston.

[0056] In general, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless otherwise expressly defined herein. Unless otherwise expressly stated, all references to "a (a) / an (an) / the (the) part, portion, element, component, arrangement, device, etc." should be open to interpretation as referring to at least one instance of a part, portion, element, device, component, arrangement, device, etc. When studying the attached claims and the following description, additional features and advantages of the inventive concept will become apparent. The skilled person recognizes that, without departing from the scope of the inventive concept, different features of the inventive concept can be combined to create embodiments other than those described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 is a very schematic illustration of a valve arrangement according to at least one exemplary embodiment of the present disclosure.

[0059] Figure 2 is a very schematic illustration of a valve arrangement according to at least further exemplary embodiments of the present disclosure.

[0060] Figure 3 is an illustration of a valve arrangement according to at least another exemplary embodiment of the present disclosure.

[0061] Detailed Description

[0062] The inventive concept will now be described more fully below with reference to the accompanying drawings in which certain aspects of the inventive concept are shown. However, the inventive concept may be embodied in many different forms and should not be construed as limited to the embodiments and aspects set forth herein; rather, embodiments are provided by way of example so that the disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in the art. Therefore, it should be understood that the inventive concept is not limited to the embodiments described herein and shown in the accompanying drawings; rather, those skilled in the art will recognize that many changes and modifications may be made within the scope of the appended claims. Throughout this specification, similar reference numerals refer to similar elements.

[0063] Figure 1 is a highly schematic illustration of a valve arrangement 1 according to at least one exemplary embodiment of the present disclosure. The valve arrangement 1 shown comprises a valve body (in Figure 1The valve plug 2 is a valve body (not specifically indicated in the schematic illustration of the valve body). The valve plug 2 can be arranged in different positions. One end position is a closed position, in which the fluid is blocked (or only a leakage flow is allowed) from the inlet of the valve body to the outlet of the valve body. The other end position is a fully open position. The valve plug 2 can move between two end positions, but can also stop at an intermediate position between the two end positions. The actuator 4 is operably connected or connectable to the valve plug 2 for moving the valve plug 2 to adjust the flow rate through the valve body. The valve arrangement 1 also includes a differential pressure regulator 6, which is configured to limit the change in differential pressure on the valve plug 2 when the fluid flows through the valve body. In this illustration, it is shown that the differential pressure regulator 6 can be arranged outside the valve body as a separate component, for example, the differential pressure regulator 6 is arranged in its own housing. However, in other examples, the differential pressure regulator 6 can be integrated into the valve body. In either case, as Figure 1 As schematically shown in FIG. 1 , the differential pressure regulator is fluidly connected to the fluid flow upstream of the valve plug 2 and the fluid flow downstream of the valve plug 2 through the first fluid channel 8 and the second fluid channel 10, respectively. Figure 1 The general direction of fluid flow is from left to right. A differential pressure regulator 6 that is fluidly connected both upstream and downstream of the valve plug 2 can compensate for pressure changes. The differential pressure regulator 6 strives to maintain a stable pressure difference on the valve plug 2. As previously mentioned, although the differential pressure regulator 6 is advantageous and improves the control of the valve plug 2 and therefore improves the control of the flow rate, there may still be some changes in the differential pressure, such as up to ±20%, and a minimum differential pressure is required for the standard differential pressure regulator to work properly. Therefore, this may increase the size of the pump head of the fluid distribution system and thereby also increase operating costs. Conversely, if the fluid distribution system cannot provide the required minimum starting pressure, pressure changes at low starting pressures will result in inaccurate flow control.

[0064] Therefore, the valve arrangement 1 also includes a flow meter 12 and a control unit 14. The flow meter 12 is configured to measure the flow rate through the valve body 2. As already mentioned, in this illustration, the general flow direction is from left to right. Therefore, the fluid flow will first flow along the flow meter 12, then through the differential pressure regulator 6, and then the fluid leaves the valve arrangement 1 after having flowed along the valve plug 2. In this exemplary embodiment, the flow meter 12 is arranged upstream of the differential pressure regulator 6 and the valve plug 2. This can be advantageous because it reduces the risk of disturbances in the flow (for example, turbulence caused by other components), which would affect the accuracy of the flow meter 12 if the flow meter 12 was arranged close to the other components. However, it is conceivable to arrange the flow meter 12 downstream of one or both of the other components, for example at an appropriate distance, so as to reduce the risk of flow disturbance effects. Furthermore, it is even conceivable to integrate the flow meter in the valve body, i.e. in a common housing with the valve plug, in this way appropriately arranged to reduce the risk of disturbances.

[0065] The control unit 14 is configured to receive a request input signal 16 representing a desired flow rate through the valve body. The request input signal 16 may be received from a central controller (such as a building management system), or from a local device (such as a thermostat in a room), or from a mobile device (such as a smart phone), or from a computer, etc. Therefore, it should be understood that the control unit 14 may be configured in various ways with various communication interfaces, including communication interfaces for wired and / or wireless communication. For example, the communication interface may be compatible with WiFi, Bluetooth, and other wireless communication standards or protocols.

[0066] The control unit 14 is configured to receive a flow input signal from the flow meter 12 that is representative of the measured flow rate. Figure 1 A first cable 18 is shown from the flow meter 12 to the control unit 14, thus indicating wired communication, but it is understood that in other examples the flow meter 12 may transmit the flow input signal wirelessly.

[0067] The control unit 14 is configured to send a control signal to the actuator 4 based on the received request input signal 16 and the received flow input signal to move the valve plug 2 or to keep the valve plug 2 in its position. Figure 1 A second cable 20 is shown between the control unit 14 and the actuator 4 , thus indicating a wired communication, but it will be appreciated that in other examples the control unit 14 may send control signals to the actuator 4 in a wireless manner.

[0068] Thereby, accurate flow control through the valve plug 2 can be obtained even at low actuation pressures.

[0069] The actuator 4 can be, for example, a thermoelectric actuator. The thermoelectric actuator is stepless, thereby allowing high accuracy to be obtained. Other advantages and functions may include those already discussed in the present disclosure. When the thermoelectric actuator expands and contracts its temperature sensing material, the thermoelectric actuator can be appropriately connected to a linearly movable valve plug. Therefore, according to at least one exemplary embodiment (regardless of whether the actuator 4 is a thermoelectric actuator), the valve plug 2 is a linearly movable valve plug.

[0070] Figure 2 is a very schematic illustration of a valve arrangement 1a according to at least a further exemplary embodiment of the present disclosure. Figure 2 The valve arrangement 1a in FIG. 1 includes a valve for Figure 1 All components shown in the valve arrangement 1 are identical to those shown in the embodiment of the present invention and are therefore assigned the same reference numerals.

[0071] like Figure 2As shown, the control unit 14 may include or have access to an electronic memory 22. The control unit 14 may be configured to determine a relationship between a change in the control signal and the effect of the change on the flow rate through the valve body based on data stored in the electronic memory 24. The control unit 14 may be configured to control the actuator 4 based on the relationship. Such electronic memory 22 may be a local electronic memory within the control unit. However, as Figure 2 As shown, such electronic storage may alternatively be located remotely, such as in a remote server 24 .

[0072] In at least some exemplary embodiments, control unit 14 is configured to operate in a self-learning model by:

[0073] - after sending the control signal to the actuator 4, continue to receive the flow input signal from the flow meter 12,

[0074] - determining the accuracy of said determined relationship between a change in the control signal and the effect on the flow rate, and

[0075] - Updating said data in electronic memory 22 based on the accuracy of said determination.

[0076] This may be relevant, for example, when the control unit 14 receives a new request input signal 16 (e.g. due to a request to change the room temperature). The control unit 14 will send a different control signal (or a different content of the control signal) to the actuator 4, requesting the actuator 4 to move the valve plug 2 to the new position. In particular, the control unit 14 may control the actuator 4 to perform a rapid change so as to achieve an approximate flow rate. By obtaining feedback from the flow meter 12, and updating the electronic memory 22 for future reference, the control unit 14 may improve its control in the future to achieve the desired flow rate more quickly. Thus, the control unit 14 may improve its accuracy already at the initial movement of the valve plug 2, and thus reduce the time required for any subsequent fine-tuning.

[0077] Figure 3 is a schematic diagram of a valve arrangement 50 according to at least another exemplary embodiment of the present disclosure. Figure 3 Most of the components are shown in cross-section. The valve arrangement 50 may be arranged in a pipe network. The pipe network may be part of a fluid distribution system, for example in a building with multiple consumption points.

[0078] The valve arrangement 50 comprises a valve body 52 having an inlet 54 for receiving a fluid into the valve body 52 and an outlet 56 for discharging the fluid from the valve body 52. ​​Thus, a flow path extends from the inlet 54 through the valve body 52 to the outlet 56. The outlet 56 is located downstream of the inlet 54, wherein the flow path is configured to guide the fluid from the inlet 54 to the outlet 56. At the inlet 54 and the outlet 56, the valve body 52 may be provided with internal threads onto which external threads of other components of the valve arrangement 50 or pipe sections of the pipe network may be screwed. Alternatively, the valve body 52 may be provided with external threads onto which internal threads of components / pipe sections may be screwed.

[0079] The valve plug 60 is located in the valve body 52. ​​The valve plug 60 can move between a closed position and a fully open position. In the closed position, fluid is blocked (or only leakage flow is allowed) from the inlet 54 to the outlet 56. The valve plug 60 can be moved to intermediate positions between the closed position and the fully open position to allow different flow rates through the valve body 52. ​​In the closed position, the valve plug 60 seals against the valve seat 62 in the valve body 52. ​​In different intermediate positions of the valve plug 60 and in the fully open position, the valve plug 60 is separated from the valve seat 62, and when the valve plug 60 moves from the closed position toward the fully open position, the available cross-sectional area for fluid flow between the valve plug 60 and the valve seat 62 increases. The valve plug 60 can be connected to a valve stem 64, such as Figure 3 shown.

[0080] The actuator 70 is operatively connected or connectable to the valve plug 60 for moving the valve plug 60 to adjust the flow rate through the valve body 52. ​​For example, Figure 3 As shown, the actuator 70 may include an engagement portion 72 that may push the valve stem 64 and thus the valve plug 60 toward the valve seat 62. A spring 74 located around the valve stem 74 may be biased to push the valve stem 64 and thus the valve plug 60 in the opposite direction (i.e., in the opening direction). Therefore, if no force is provided from the actuator 70 to the valve stem 64, the valve plug 60 will reach its fully open position. This is generally referred to as a "normally open" type valve. However, it should be understood that the overall inventive concept may also be applied to a "normally closed" type valve, i.e., where the valve plug is in its closed position when no force (e.g., pulling force) from the actuator is applied.

[0081] As can be appreciated from the above, the actuator 70 can be suitably configured to enable the valve plug 60 to move between two end positions of the valve plug 60 (ie, the closed position and the fully open position), and to enable the valve plug 60 to move to an intermediate position between the two end positions.

[0082] The differential pressure regulator 80 is configured to limit the change in differential pressure across the valve plug 60 when fluid flows through the valve body 52. ​​The differential pressure regulator 80 is in fluid communication with both the fluid flow upstream of the valve plug 60 and the fluid flow downstream of the valve plug 60. Figure 1 and Figure 2 Unlike the example in Figure 3 In the present example, the differential pressure regulator 80 is disposed within the valve body 52. ​​Thus, the differential pressure regulator 80 and the valve plug 60 may be disposed in a common housing. However, it should be understood that in other exemplary embodiments, the valve plug 60 and actuator 70 shown may be combined with an external differential pressure regulator that is disposed as a separate component outside the valve body 52 (but still in fluid communication with both the fluid flow upstream of the valve plug 60 and the fluid flow downstream of the valve plug 60).

[0083] The differential pressure regulator 80 shown is only an example, and other types of differential pressure regulators can also be considered. The differential pressure regulator 80 shown includes a movable separation member, which is shown in the form of a film 82. However, in other examples, the movable separation member can be in the form of a piston. The film 82 is fixed to a film support 84, which is connected to a closure member 86 and can move with the closure member 86. The first side of the film 82 is in fluid communication with the fluid flow fluid upstream of the valve plug 60, whereby the fluid applies a first pressure to the film 82, thereby generating a first force, which is the product of the first pressure and the area of ​​the first side subjected to the first pressure. Similarly, the opposite second side of the film 82 is in fluid communication with the fluid flow fluid downstream of the valve plug 60, whereby the fluid applies a second pressure to the film 82, thereby generating a second force, which is the product of the second pressure and the area of ​​the second side subjected to the second pressure. Therefore, the difference between the first force and the second force controls the movement of the film 82 and the film support 84 together with the closure member 86.

[0084] As shown, the spring element 88 is arranged between the cover 90 and the membrane support 84 to exert a third force on at least a portion of the membrane support 84, and the cover 90 is arranged in the valve body 52. ​​Thus, the direction of the third force is at least partially the same as the direction of the second force, that is, it acts to open the closing member 86. The closing member 86 will act as a differential pressure valve component, which moves up or down to compensate for any differential pressure changes that may occur. The compensation causes the differential pressure on the valve plug 60 to remain essentially unchanged, which acts as a control valve component. In other words, the differential pressure valve component can limit the differential pressure faced by the control valve component. Therefore, despite the pressure level changes in the pipeline network, the operating conditions for the control valve component can be maintained at a suitable level.

[0085] The valve arrangement 50 also includes a flow meter 100, which is configured to measure the flow rate through the valve body. The flow meter 100 is illustrated here as a type in which a ball 102 is caused to move back and forth due to the kinetic energy of the fluid flow, and during this back and forth movement, the ball will temporarily block a light beam, wherein the frequency with which the light beam is blocked is a measure of the speed of the ball 102, and therefore a measure of the flow rate. However, this is only one example of a flow meter that may be envisaged, and it should be understood that other types of flow meters may also be envisaged, such as, for example, ultrasonic flow meters.

[0086] The valve arrangement 50 further comprises a control unit 110 which is schematically illustrated here as being operatively connected both to the actuator 70 and to the flow meter 100 . Figure 3 The control unit 110 in the embodiment may have Figure 1 and Figure 2 The control unit 14 in the embodiment of the present invention has the corresponding functions and can be configured to perform the functions of Figure 1 and Figure 2 The control unit 14 in the control unit 14 performs corresponding actions.

[0087] exist Figure 3 , a first signal cable 112 connects the control unit 110 to the flow meter 100. A second signal cable 114 connects the control unit 110 to the actuator 70. Therefore, the control unit 110 is illustrated herein as being in wired communication with both the flow meter 100 and the actuator 70, however, it should be understood that in other exemplary embodiments, the control unit 110 may be arranged to be in wireless communication with one or both of the flow meter 100 and the actuator 70. In other exemplary embodiments, the control unit may be integrated with the actuator in a common actuator assembly and provided as an integral component. In other exemplary embodiments, the control unit may be integrated with the flow meter in a common flow meter assembly. In addition, as in combination Figure 1 and Figure 2 As discussed, Figure 3 The control unit 110 in may include or have access to electronic storage, which may thus be local or remote electronic storage.

[0088] Similar to About Figure 1 and Figure 2 Discussion, Figure 3The control unit 110 in is configured to receive a request input signal 116 representing a desired flow rate through the valve body 52. ​​Such a request input signal 116 can be a wireless or wired request input signal 116. The control unit 110 is also configured to receive a flow input signal (here via a first signal cable 112) representing a measured flow rate from the flow meter 100. The control unit 110 is configured to send a control signal (here via a second signal cable 114) to the actuator 70 based on the received request input signal 116 and the received flow input signal to move the valve plug 60 or keep the valve plug 60 in its position.

[0089] It should be understood that any signal discussed in this disclosure may be a digital signal or an analog signal. In either case, a signal may transmit data from one device to another. For example, a signal may be a logical signal describing a bit stream; a signal may be considered as a code sequence represented by a physical quantity; a signal may refer to a time-varying voltage, current, or electromagnetic wave that carries information, etc.

[0090] Figure 3 The actuator 70 in may suitably be a proportional actuator. Thus, a control signal (suitably a digital control signal) from the control unit 110 may set the position of the actuator 70, which in turn corresponds to the position of the valve plug 60, which in turn corresponds to the approximate flow rate through the valve body 52. ​​In some exemplary embodiments, the actuator 70 may be provided with one or more position detection components, such as optical sensors, magnetic sensors or mechanical sensors / switches, etc., to determine the position of the actuator 70. Figure 3In the example of , such a sensor or switch can, for example, determine the position of the engagement portion 72 of the actuator 70, as the valve plug 60 will follow the movement of the engagement portion 72 via the valve stem 62. Therefore, the control unit 110 can be configured to receive position feedback from the actuator 70 indicating the current position of the actuator 70. The control signal from the control unit 110 can be based on such position feedback in order to move the actuator 70 (and in this case the engagement portion 72 of the actuator 70) towards a desired position, which in turn corresponds to a desired position of the valve plug 60, which in turn roughly corresponds to a desired flow rate through the valve body 52. ​​Therefore, the control unit 110 may not necessarily need to access electronic memory, but can quickly find the approximate position based on such position feedback from the actuator 70, and can then make fine adjustments based on the flow input signal from the flow meter 100. As already explained, due to various tolerances, even for valves that are considered good and differential pressure regulators, it is desirable to have a tolerance of ±20% relative to the desired flow rate. By using position feedback, a fast initial move can be made to obtain an approximate desired flow rate, and then fine adjustments can be made. By quickly reaching the approximately correct position, larger oscillations that move the valve up and down to reach the correct position, which might occur if the control unit 110 tried to quickly reach the correct position relying solely on the flow input signal, can be avoided (larger moves generally become less accurate in absolute terms than smaller moves).

[0091] It can be understood from the above that, in a general sense, according to at least some exemplary embodiments (not limited to those shown in the drawings), upon receiving a request input signal or a change in a request input signal, the control unit is configured to control the movement of the valve plug in two steps:

[0092] - firstly, the control unit controls the actuator based on the request input signal without regard to any flow input signal from the flow meter so as to move the valve plug to an approximate position approximately corresponding to the desired flow rate, and

[0093] -Then, based on the flow input signal from the flow meter, the control unit controls the actuator to fine-tune the position of the valve plug to a position that more accurately produces the desired flow rate.

[0094] References Figure 3 (But it also applies to other examples, such as Figure 1 and Figure 2 According to at least one exemplary embodiment, the control unit 110 is configured to:

[0095] - based on the received request input signal 116, initially controlling the actuator 70 to move to a position approximately corresponding to the desired flow rate, and subsequently,

[0096] - Based on the received flow input signal (which represents the fluid flow rate measured after said initial control of the actuator 70), fine-tune the position of the actuator 70 (in this case the engaging portion 72 of the actuator 70) so as to obtain a flow rate closer to the desired flow rate.

[0097] The control unit 110 can be appropriately configured to operate in a self-learning model. The control unit 110 can use a stored historical date representing a control event in which the fine adjustment is performed after the actuator 70 has moved to a corresponding position roughly corresponding to the corresponding desired flow rate. Such historical data can be stored, for example, in a local or remote electronic memory, such as the electronic memory discussed previously. When a change in the desired flow rate is received via the request input signal 116, the control unit 110 can modify the control signal based on the stored historical data to reduce the time required for subsequent fine adjustments to obtain the desired flow rate. Therefore, each time a new request input signal (requiring the valve plug 60 to be moved) is received, the control unit 110 can appropriately store the parameters of the control action, such as the initial movement and the required fine adjustment, for future reference. Historical events that require smaller fine adjustments can be used for positive reinforcement in the self-learning model, while events that require larger fine adjustments can be used for negative reinforcement in the self-learning model. In this way, the control unit 110 can learn to improve the control action for different request input signals 116 and / or for different changes in the request input signal 116.

[0098] The valve arrangement 50, in particular the control unit 110, may also be suitably used to detect faults. For example, after sending a control signal to the actuator 70 to move to a new position, the control unit 110 may be configured to continue to receive a flow input signal from the flow meter 100. When it is detected that the flow rate measured by the flow meter 100 deviates from a predefined allowable deviation, the control unit 110 may determine that a fault has occurred in the valve arrangement 50 or in a pipe network connected to the valve arrangement 50. For example, the predefined allowable deviation may be set to exceed the expected tolerance. Just to give an illustrative example, if the expected tolerance is ±20%, the predefined allowable deviation may be set to ±30%, for example. Suitably, the control unit 110 may be substantially continuously connected to the flow meter 100.

[0099] Upon detecting that a fault has occurred, the control unit 110 may execute a sequence of self-diagnostic routines to identify which part of the valve arrangement has failed or to determine that the fault is in the pipe network to which the valve arrangement 50 is connected.

[0100] It should be understood that Figure 3 The various operations and control actions performed by the control unit 110 in the Figure 1 and Figure 2 The control unit 14 in the reference Figure 2 , where it is illustrated that the valve arrangement 1a may also include one or more temperature sensors 26. Such one or more temperature sensors may also be located at Figure 3 The temperature sensor 26 is configured to measure the temperature in the fluid. As shown, the temperature sensor 26 can be appropriately located downstream of the valve plug 2, however, the specific location is not critical for temperature measurement because the temperature of the fluid does not change much when the fluid flows through the valve arrangement 1a. The control unit 14 is configured to receive temperature information indicating the temperature of the fluid from the temperature sensor 26. The control unit 14 is configured to detect a failure of the flow meter 12 based on the received temperature information and based on the received flow input signal from the flow meter 12. For example, in a case where the flow meter 12 does not detect any flow rate even if the actuator 4 has moved the valve plug to the open position, then the information from the temperature sensor may still be able to reveal whether there is flow. If the temperature is changing when the valve is open, it is likely that fluid is passing through the valve body.

[0101] Figure 1 and Figure 2 The control unit 14 and Figure 3 The control unit 110 in the embodiment can be configured to ignore any flow input signal from the flow meter at very small openings of the valve plugs 2, 60, respectively. As explained previously, at very low flow rates, the accuracy of many commercially available flow meters is insufficient and may result in incorrect control actions from the control unit. Therefore, when the request input signal (16, 116) indicates a desired flow rate that is equal to or lower than a predefined flow rate, then the control unit (14, 110) can be configured to ignore any flow input signal received from the flow meter (12, 100) and send a control signal based on the request input signal (16, 116).

[0102] Furthermore, the control unit (14, 110) may be configured to periodically control the actuator (4, 70) to move the valve plug (2, 60) to an open position for which the resulting flow rate through the valve body (52) is expected to have a magnitude measurable by the flow meter (12, 100). This procedure enables the control unit to detect an incorrect functioning of the valve arrangement.

Claims

1. A valve arrangement for controlling fluid flow, comprising: - a valve body having an inlet for receiving a fluid into the valve body and an outlet for discharging the fluid from the valve body, a valve plug located in the valve body and movable between a closed position, in which a fluid flow from the inlet to the outlet is blocked, and a fully open position, in which only a leakage flow is allowed from the inlet to the outlet, an actuator operatively connected or connectable to the valve plug for moving the valve plug to adjust the flow rate through the valve body, a differential pressure regulator comprising a movable separating member having a first side and an oppositely facing second side, the first side being in fluid communication with a fluid flow upstream of the valve plug and the second side being in fluid communication with a fluid flow downstream of the valve plug, wherein the differential pressure regulator is configured such that the movable separating member is movable in response to a differential pressure between the first side and the second side and such that movement of the movable separating member counteracts pressure changes on the valve plug when fluid flows through the valve body, - a flow meter configured to measure a flow rate through the valve body, - a control unit configured to receive: i) a request input signal representing a desired flow rate through the valve body, and ii) a flow input signal from said flow meter representing a measured flow rate, The control unit is configured to send a control signal to the actuator based on the received request input signal and the received flow input signal to move the valve plug or keep the valve plug in its position.

2. A valve arrangement according to claim 1, wherein The actuator is a thermoelectric actuator.

3. A valve arrangement according to any one of claims 1 to 2, wherein: The control unit comprises an electronic memory or has access to an electronic memory, wherein the control unit is configured to determine a relationship between a change in the control signal and an effect of the change on the flow rate through the valve body based on data stored in the electronic memory, wherein the control unit is configured to control the actuator based on the relationship.

4. A valve arrangement according to claim 3, wherein: The control unit is configured to operate in a self-learning model by: - after sending the control signal to the actuator, continuing to receive the flow input signal from the flow meter, - determining the accuracy of said determined relationship between said control signal change and said effect on flow rate, and -updating said data in said electronic memory based on the accuracy of said determination.

5. A valve arrangement according to any one of claims 1 to 4, wherein: The actuator is a proportional actuator, wherein the control signal from the control unit sets a position of the actuator, which in turn corresponds to a position of the valve plug, which in turn corresponds to an approximate flow rate through the valve body.

6. A valve arrangement according to any one of claims 1 to 4, wherein: The control unit is configured to receive position feedback from the actuator indicating a current position of the actuator, wherein the control signal from the control unit is based on the position feedback so as to move the actuator towards a desired position of the actuator, which in turn corresponds to a desired position of the valve plug, which in turn roughly corresponds to a desired flow rate through the valve body.

7. A valve arrangement according to claim 5 or 6, wherein: The control unit is configured to: - based on the received request input signal, initially controlling the actuator to move to a position approximately corresponding to the desired flow rate, and subsequently, - fine-tuning said position of said actuator so as to obtain a flow rate closer to said desired flow rate based on a received flow input signal representing a flow rate of a fluid measured after said initial control of said actuator.

8. A valve arrangement according to claim 7, wherein The control unit is configured to operate in a self-learning model by: - using stored historical data representing control events, wherein fine-tuning is performed after the actuator has been moved to a respective position approximately corresponding to a respective desired flow rate, and - upon receiving a change in the desired flow rate via the request input signal, modifying the control signal based on the stored historical data to reduce the time required for subsequent fine-tuning to achieve the desired flow rate.

9. A valve arrangement according to any one of claims 1 to 8, wherein: The control unit is configured to: - continuing to receive a flow input signal from the flow meter after sending the control signal to the actuator for moving the actuator to a new position, and - upon detecting that the flow rate measured by the flow meter deviates by more than a predefined permissible deviation, determining that a fault has occurred in the valve arrangement or in a pipe network connected to the valve arrangement.

10. A valve arrangement according to claim 9, wherein The control unit is configured to: - When a fault is detected, a self-diagnostic program sequence is executed to identify which part of the valve arrangement has failed or to determine that the fault is in the pipe network to which the valve arrangement is connected.

11. The valve arrangement according to claim 9 or 10 further comprises one or more temperature sensors configured to measure the temperature in the fluid, wherein the control unit is configured to receive temperature information indicating the temperature of the fluid from the temperature sensor, wherein the control unit is configured to detect a fault of the flow meter based on the received temperature information and based on a received flow input signal from the flow meter.

12. A valve arrangement according to any one of claims 1 to 11, wherein: When the request input signal indicates a desired flow rate that is equal to or lower than a predefined flow rate, then the control unit is configured to ignore any flow input signal received from the flow meter and to send the control signal based on the request input signal.

13. A valve arrangement according to claim 12, wherein: The control unit is configured to periodically control the actuator to move the valve plug to an open position for which a resulting flow rate through the valve body is expected to have a magnitude measurable by the flow meter.

14. A valve arrangement according to any one of claims 1 to 13, wherein: The movable separating member is in the form of a membrane or a piston.

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