System and flow sensor for measuring a flow of a fluid measuring medium

Abstract

The invention relates to a flow sensor comprising: - a housing (100), wherein the housing (100) has an inlet channel (110) for receiving the fluid measuring medium, an outlet channel (120) for discharging the fluid measuring medium, a measuring channel (130) extending between the inlet channel (110) and outlet channel (120) and at least one secondary channel (140) extending between the inlet channel (110) and the outlet channel (120), and more particularly connected in parallel to the measuring channel (130); - a sensor element (200) arranged in the measuring channel (130) for sensing a physical measurement variable with regard to a flow of the fluid measurement medium; and – a first more particularly bolt-shaped closure element (300), wherein the first closure element (300) is designed and attached to the housing (100) such that the first closure element (300) can be moved in relation to a first fluid transfer (150) or a second fluid transfer (160) into at least one first position (P1) and a second position (P2), wherein the first closure element (300), in the second position (P2), closes the first fluid transfer (150) or the fluid transfer (160), and wherein the first fluid transfer (150) or the second fluid transfer (160) is not closed in the first position (P1) of the first closure element (300). The invention also relates to a system that contains the flow sensor according to the invention.

Description

[0001] System and flow sensor for measuring the flow of a fluid measuring medium

[0002] The invention relates to a flow sensor for measuring the flow of a fluid medium. Furthermore, the invention relates to a system comprising a control / evaluation unit and a flow sensor according to the invention.

[0003] Flow sensors are used to determine the flow rate, flow velocity, volume flow, mass flow, or related quantities of a measuring medium or fluid, such as a gas, gas mixture, or liquid. There are various types of flow sensors, such as thermal flow sensors, Coriolis flow sensors, ultrasonic flow sensors, microwave flow sensors, etc.

[0004] Thermal flow sensors, for example, utilize the fact that a (flowing) measuring medium transports heat away from a heated surface. Thermal flow sensors typically consist of several functional elements, usually at least one low-resistance heating element and one high-resistance resistance element that serves as a temperature sensor. Alternatively, thermal flow sensors are constructed with several low-resistance heating elements as a heater and a temperature sensor.

[0005] Flow sensors and modules are designed for a specific flow range, which is usually defined by the geometry of the flow channel. This requires adjustments to the sensor or flow channel for each flow range. Depending on the application, individual adjustments to channel geometries may not be desirable, for example, because the market is too small to motivate such adjustments (this usually applies to small or medium-sized production runs).

[0006] It is known from the prior art to use a so-called "bypass" channel, in which the flow sensor is located and which is fluidically connected parallel to the flow channel. The bypass channel allows the use of an identical sensor type in different applications. For this purpose, not the entire flow channel, but only the bypass channel, needs to be geometrically adapted to the desired flow range.

[0007] However, even adapting the bypass channel often involves considerable effort and development, which is why such adaptation is often neglected, especially for small and medium-sized applications. Based on this problem, the invention is based on the objective of presenting a flow sensor that can be used in various flow ranges.

[0008] The object is achieved by a flow sensor according to claim 1 and by a system according to claim 11.

[0009] With regard to the flow sensor, it is provided that it serves to measure a flow of a fluid measuring medium and comprises: a housing, wherein the housing has an inlet channel for receiving the fluid measuring medium, an outlet channel for discharging the fluid measuring medium, a measuring channel extending between the inlet channel and the outlet channel, and at least one secondary channel extending between the inlet channel and the outlet channel and, in particular, connected parallel to the measuring channel, wherein a first fluid transfer is provided for connecting the inlet channel and the secondary channel, and wherein a second fluid transfer is provided for connecting the secondary channel and the outlet channel; a sensor element arranged in the measuring channel for detecting a physical measurement variable relating to a flow of the fluid measuring medium;and a first bolt-shaped closure element, wherein the first closure element is designed and attached to the housing such that the first closure element is movable into at least a first and a second position with respect to the first fluid transfer or the second fluid transfer, wherein the first closure element closes the first fluid transfer or the fluid transfer in the first position, and wherein the first fluid transfer or the second fluid transfer is unlocked in the second position of the first closure element.;

[0010] The invention consists in providing a housing that forms a variable bypass channel. According to the invention, a main channel and at least one secondary channel are provided in the housing. The secondary channel can be closed at a first fluid transfer point by at least one closure element, for example, a piston, a bolt, a screw, or the like.

[0011] This allows the proportion of flow flowing through the measuring channel to be adjusted. This makes adjustments to the flow channel very simple and cost-effective. The flow range can be defined according to the application and requirements. Even applications that require very different flow rates at certain times are feasible. For example, dosing pumps handle very small flow rates during dosing, but require large flow rates for the cleaning cycle. This is made possible by adjusting the closure element.

[0012] The measured quantity with regard to flow is understood to be, among other things, a measure of the flow velocity, the volume flow, the mass flow, or similar, of the measuring medium.

[0013] One embodiment of the flow sensor provides a second bolt-shaped closure element, which is configured and attached to the housing in such a way that the second closure element is movable into at least a first and a second position with respect to the first fluid transfer or the second fluid transfer not influenced by the first closure element. The second closure element closes this corresponding fluid transfer in the first position, and this corresponding fluid transfer is unlocked in the second position of the second closure element. The second closure element provides redundancy to the first closure element.

[0014] An advantageous embodiment of the flow sensor provides that the first closure element and / or the second closure element can be adjusted to intermediate positions between the first and second positions. This allows the cross-section of the corresponding fluid transfer channel to be closed not only completely, but also partially in stages. This allows the flow distribution into the measuring and secondary channels to be adjusted even more precisely, thus expanding the application area. By using both closure elements, with at least one of the closure elements adjustable to intermediate positions, the flow distribution can be further refined.

[0015] An advantageous embodiment of the flow sensor provides for the first closure element and / or the second closure element to be continuously adjustable. This allows for individual positioning of the corresponding closure element, allowing the flow range to be finely adjusted as required.

[0016] According to an advantageous embodiment of the flow sensor according to the invention, the housing comprises one or more further secondary channels extending between the inlet channel and the outlet channel, and in particular connected parallel to the measuring channel, wherein for each further secondary channel at least one further first fluid transfer is provided for connecting the inlet channel and the corresponding further secondary channel and in each case one further second fluid transfer is provided for connecting the corresponding secondary channel and the outlet channel. The flowing fluid is thereby distributed between the measuring channel and all secondary channels. The first closure element can be adjusted to at least one third position, in which third position the first fluid transfer is closed together with at least one further first fluid transfer and / or together with all further first fluid transfers.An additional position is provided for each additional secondary channel in order to be able to close all secondary channels using the first closure element.

[0017] Furthermore, it is provided that the second closure element is configured and attached to the housing in such a way that the second closure element can be adjusted to at least one third position, in which third position the second fluid transfer is closed jointly with at least one further second fluid transfer and / or jointly with all further second fluid transfers. A further position is provided for each additional secondary channel in order to be able to close all secondary channels by means of the first closure element.

[0018] By providing additional secondary channels and the corresponding additional positions of the closure elements, a fine adjustment of the flow area is also possible.

[0019] A variant of the flow sensor provides for at least one additional bolt-shaped closure element for each additional secondary channel to close the corresponding additional first fluid transfer and / or additional second fluid transfer. In this variant, therefore, a separate closure element is provided for each fluid transfer rather than a common closure element for the fluid transfers between the inlet channel and the secondary channels, or a common closure element for the fluid transfers between the secondary channels and the outlet channel.

[0020] In an advantageous development, the flow sensor comprises an actuator, which is configured and connected to the first closure element and / or the second closure element in such a way that the actuator generates a movement of the first closure element or the second closure element to control the respective first positions, the second positions, the intermediate positions, and the third positions. The closure elements are thus not adjusted manually, but by the actuator. For this purpose, the actuator comprises an actuator, in particular a motor.

[0021] Flow sensor according to one of the preceding claims, wherein the flow sensor is a thermal flow sensor. The type and measuring principle (e.g., constant temperature amemory (CTA), constant power amemory (CPA), etc.) of the thermal flow sensor can be freely selected.

[0022] With regard to the system, it is provided that it comprises a flow sensor according to the invention and a control / evaluation unit, wherein the control / evaluation unit is designed to query a measured value of the physical measurement variable relating to the flow of the fluid measuring medium from the flow sensor and / or to adjust at least one of the closure elements to at least one of the positions using the actuator. The control / evaluation unit is, for example, a circuit with an ASIC or a microprocessor, or a PC or a mobile device, e.g., a smartphone or a tablet.

[0023] Advantageously, the control / evaluation unit is designed to compare the measured value with at least one limit value and, if the limit value is exceeded or undershot, to adjust at least one of the closure elements by means of the actuator such that the measured value no longer falls below or exceeds the limit value. This implements a control functionality that can be advantageously used, particularly under changing conditions, such as a strongly fluctuating flow rate.

[0024] The invention is explained in more detail with reference to the following figures.

[0025] Fig. 1 : a horizontal cross-sectional view of a flow sensor described in a first embodiment;

[0026] Fig. 2: a vertical cross-sectional view of the flow sensor described in the first embodiment;

[0027] Fig. 3: a horizontal cross-sectional view of a flow sensor described in a second embodiment; and

[0028] Fig. 4: an embodiment of the system according to the invention.

[0029] 1 and 2 show a first exemplary embodiment of the flow sensor DS according to the invention. Fig. 1 shows a horizontal cross-section through the flow sensor 1, or a plan view of the flow sensor 1, in which the counterpart 400 is omitted. Fig. 2 shows a cross-section through the flow sensor DS at the level of the measuring channel 130. The flow sensor consists of a one-part or multi-part housing 100. In the case of a one-part housing 100, this is made of plastic, for example, and is manufactured using an additive manufacturing process, for example, using 3D printing. In the case of a multi-part housing, this is made of a plastic or a metallic material.

[0030] Several channels are embedded in the housing:

[0031] An inlet channel 110 and an outlet channel 120 are provided, by means of which a fluid measuring medium can be introduced into and discharged from the housing 100. The arrows indicate the flow velocity of the measuring medium. Furthermore, a measuring channel 130 and two secondary channels 140 are provided. First fluid transfers 150 connect the inlet channel 110 and the secondary channels. Second fluid transfers 160 connect the inlet channel 110 and the secondary channels. Furthermore, fluid transfers are also provided between the inlet channel 110 and measuring channel 130 and between the measuring channel 130 and outlet channel 120. The fluid transfers 150, 160 are provided here as holes in the material of the housing 100, which form channels between the corresponding secondary channels 140, 170 and the inlet channel 110 or outlet channel 120. In the present example, the secondary channels each share a hole, but separate fluid transfers 150, 160 are still formed.

[0032] The flow sensor DS can therefore be connected to a flow channel and acts, for example, as a bypass channel to the flow channel.

[0033] A flow sensor 200, in particular a thermal flow sensor 200, is mounted in the measuring channel 130. This sensor detects a measured variable of the measuring medium flowing through the measuring channel, for example, a measure of the flow velocity, the volume flow, the mass flow, or the like.

[0034] The measured variable measured by the flow sensor 200 in the measuring channel 130 is a measure of the flow velocity, or volume flow and / or mass flow, of the measuring medium present in the flow channel. The flow sensor 200 is calibrated accordingly for this purpose. Depending on the application, different flow regimes exist in the flow channel. For this purpose, the geometry of the measuring channel 130 must be designed accordingly to prevent flows in the measuring channel 130 that can no longer be detected by the flow sensor 200 due to a flow that is too high or too low. The flow sensor DS according to the invention offers the possibility of adjusting the flow regime in the measuring channel 130 without having to adapt the geometry of the measuring channel 130. A first closure element 300 is provided for this purpose. In the present case, this has a bolt-shaped form and can be inserted into the housing 100.Depending on the position, i.e., the degree to which the closure element 300 penetrates the housing 100, one or more of the secondary channels 140, 170 can be closed. This occurs when the closure element 300 crosses the corresponding first fluid connections 150 and closes their channel cross-section. This changes the pressure drop, which in turn changes the fluid distribution into the corresponding channels 130, 140, 170.

[0035] In a first position P1, the closure element 300 is inserted into the housing 100 so far that the closure element 300 does not contact any of the fluid connections. The measuring medium flowing through the flow sensor DS is distributed proportionally among these measuring and secondary channels 130, 140, 170 according to the geometries of the measuring and secondary channels 130, 140, 170.

[0036] In a second position P2, the closure element 300 is inserted so far into the housing 100 that the closure element 300 encounters the fluid connection 150 connecting the inlet channel 110 to the secondary channel 140, and its cross-section is completely worn away. The measuring medium flowing through the flow sensor DS is thus distributed only between the measuring channel 130 and the additional secondary channel 170, resulting in a higher flow rate in each of these channels 130 and 170 compared to position P1.

[0037] In a third position P3, the closure element 300 is inserted into the housing 100 to such an extent that the closure element 300 encounters the fluid connection 150 connecting the inlet channel 110 to the secondary channel 140 and the fluid connection connecting the inlet channel 110 to the secondary channel 170, completely closing their cross-sections. The measuring medium flowing through the flow sensor DS thus flows only through the measuring channel 130, resulting in a higher flow rate in this measuring channel 130 compared to positions P1 and P2.

[0038] In a fourth position P4, the closure element 300 is inserted into the housing 100 to such an extent that the closure element closes the cross sections of all fluid connections of the channels 130, 140, 170. No more measuring medium flows through the flow sensor DS.

[0039] Fig. 3 shows a second embodiment of the flow sensor. This differs from the first embodiment in that instead of two secondary channels, only a single large secondary channel 140' is provided.

[0040] The closure element 300 is movable in three positions: In a first position P1', the closure element 300 is inserted into the housing 100 so far that the closure element 300 does not impinge on any of the fluid connections. The measuring medium flowing through the flow sensor DS is distributed proportionally between the measuring channel 130 and the secondary channel 140' according to the geometries of the measuring and secondary channels 130, 140'.

[0041] In a second position P2', the closure element 300 is inserted so far into the housing 100 that the closure element 300 encounters the fluid connection 150 connecting the inlet channel 110 to the secondary channel 140', and its cross-section is completely worn out. The measuring medium flowing through the flow sensor DS thus flows only through the measuring channel 130, resulting in a higher flow rate in this measuring channel 130 compared to position P1'.

[0042] In a third position P3', the closure element 300 is inserted into the housing 100 to such an extent that the closure element 300 closes the cross sections of all fluid connections of the channels 130, 140'. No more measuring medium flows through the flow sensor DS.

[0043] The second embodiment also offers the possibility of continuously reducing the cross-section of the fluid connection 150. For this purpose, the closure element 300 can be adjusted to intermediate positions between positions P1' and P2'. This offers a degree of adaptability to different applications.

[0044] Fig. 4 shows an embodiment of the system according to the invention. The flow sensor DS corresponds to that of the first embodiment (see Fig. 1 and Fig. 2). Additionally, an actuator 500 is provided, which can move the closure element 300 in the housing 100 and adjust the positions P1, P2, P3, P4.

[0045] Additionally, a control / evaluation unit 600 can be provided. This serves to query the measured value from the flow sensor 200 and to control the actuator to move the closure element 300 to the positions P1 to P4. A controller functionality is also feasible, in which the control / evaluation unit 600 moves the closure element 200 according to the variables detected by the flow sensor 200. For example, the positions are controlled when a limit value is exceeded or undershot, so that the flow sensor would be "out of spec." By controlling a suitable position, the flow sensor 200 returns to the desired specification range.

[0046] The invention is not limited to the exemplary embodiments listed and shown in Figs. 1 to 4. Combinations of the exemplary embodiments are also encompassed. It is also possible to provide a second closure element that can close the second fluid connections (between the secondary channels and the outlet channel, or between the measuring channel and the outlet channel). It is also possible to provide a separate closure element for each of the fluid connections.

[0047] List of reference symbols

[0048] 100 housings

[0049] 110 Inlet channel

[0050] 120 exhaust channel

[0051] 130 measuring channels

[0052] 140 side channel

[0053] 150 first fluid transfer

[0054] 160 second fluid transfer

[0055] 170 additional branch channels

[0056] 200 sensor elements

[0057] 300 closure element

[0058] 400 counterpart

[0059] 500 Actuator

[0060] 600 Control / Evaluation Unit

[0061] DS flow sensor

[0062] P1 first position of the locking element

[0063] P2 second position of the locking element

[0064] P3 third position of the locking element

Claims

A flow sensor (DS) for measuring a flow of a fluid measuring medium, comprising: a housing (100), wherein the housing (100) has an inlet channel (110) for receiving the fluid measuring medium, an outlet channel (120) for discharging the fluid measuring medium, a measuring channel (130) extending between the inlet channel (110) and the outlet channel (120), and at least one secondary channel (140) extending between the inlet channel (110) and the outlet channel (120) and, in particular, connected parallel to the measuring channel (130), wherein a first fluid transfer (150) is provided for connecting the inlet channel (110) and the secondary channel (140), and wherein a second fluid transfer (160) is provided for connecting the secondary channel (140) and the outlet channel (120); a sensor element (200) arranged in the measuring channel (130) for detecting a physical measurement variable relating to a flow of the fluid measuring medium; and a first, in particular bolt-shaped,Closure element (300), wherein the first closure element (300) is designed and attached to the housing (100) in such a way that the first closure element (300) is movable with respect to the first fluid transfer (150) or the second fluid transfer (160) into at least a first position (P1) and a second position (P2), wherein the first closure element (300) closes the first fluid transfer (150) or the fluid transfer (160) in the second position (P2), and wherein the first fluid transfer (150) or the second fluid transfer (160) is unlocked in the first position (P1) of the first closure element (300). Flow sensor according to claim 1, comprising a second, in particular bolt-shaped, closure element, wherein the second closure element is designed and attached to the housing (100) in such a way that the second closure element with respect to the first fluid transfer (150) or second fluid transfer (160),which is not influenced by the first closure element, is movable into at least a first position and a second position, wherein the second closure element closes this corresponding fluid transfer (150, 160) in the second position, wherein this corresponding fluid transfer (150, 160) is unlocked in the first position of the second closure element.

3. Flow sensor according to claim 1 or claim 2, wherein the first closure element (300) and / or the second closure element is adjustable in intermediate positions between the first position (P1) and the second position (P2).

4. Flow sensor according to claim 3, wherein the first closure element (300) and / or the second closure element is continuously adjustable.

5. Flow sensor according to one of the preceding claims, wherein the housing (100) comprises one or more further secondary channels (170) extending between the inlet channel (110) and the outlet channel (120) and in particular connected parallel to the measuring channel (130), wherein for each further secondary channel (170) at least one further first fluid transfer is provided for connecting the inlet channel (110) and the corresponding further secondary channel (170) and in each case one further second fluid transfer is provided for connecting the corresponding further secondary channel (170) and the outlet channel (120).

6. Flow sensor according to claim 5, wherein the first closure element (300) is designed and attached to the housing (100) in such a way that the first closure element (300) can be adjusted to at least one third position (P3), in which third position (P3) the first fluid transfer (150) is closed together with at least one further first fluid transfer and / or together with all further first fluid transfers.

7. Flow sensor according to claim 5 or 6, wherein the second closure element is designed and attached to the housing (100) in such a way that the second closure element can be adjusted to at least one third position, in which third position the second fluid transfer (160) is closed together with at least one further second fluid transfer and / or together with all further second fluid transfers.

8. Flow sensor according to claim 5, wherein the flow sensor (DS) has at least one further bolt-shaped closure element for each further secondary channel for closing the respective further first fluid transfer and / or further second fluid transfer.

9. Flow sensor according to one of the preceding claims, wherein the sensor element (200) is a thermal flow sensor. Flow sensor according to one of the preceding claims, comprising an actuator (500) which is configured and connected to the first closure element (300) (300) and / or to the second closure element such that the actuator (500) generates a movement of the first closure element (300) or the second closure element to control the respective first positions (P1), the second positions (P2), the intermediate positions, and the third positions (P2). System comprising a flow sensor (DS) according to claim 10 and a control / evaluation unit (600), wherein the control / evaluation unit (600) is configured to query a measured value of the physical measurement variable relating to the flow of the fluid measurement medium from the flow sensor and / or to adjust at least one of the closure elements (300) to at least one of the positions (P1, P2, P3) by means of the actuator (500).System according to claim 11, wherein the control-evaluation unit (600) is designed to compare the measured value with at least one limit value and, if the limit value is exceeded or undershot, to adjust at least one of the closure elements (300) by means of the actuator (500) such that the measured value no longer falls below or exceeds the limit value.

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