Positive displacement pump and pump system

Abstract

The present application describes a positive displacement pump for delivering a material to be delivered, comprising a measurement assembly having at least one measurement channel through which at least a portion of the material to be delivered delivered by the pump can flow, the at least one measurement channel having a non-circular cross-section, and the measurement assembly having a pressure sensor assembly, and a pressure sensor for detecting pressure acting at positions spaced apart in the flow direction of the at least one measurement channel when at least a portion of the material to be conveyed conveyed by the pump flows through the at least one measurement channel. A system having a positive displacement pump and a control unit is also described.

Description

Technical Field

[0001] The present invention relates to a positive displacement pump and a pump system with such a positive displacement pump. Background Art

[0002] Positive displacement pumps (such as eccentric screw pumps, rotary piston pumps, screw pumps or hose pumps) are used to convey the material to be conveyed. The material to be conveyed is a free-flowing material to be conveyed, especially a liquid or a (e.g., low or high) viscous material to be conveyed. Examples of such materials to be conveyed include process liquids used in workpiece production, such as coolant, oil, varnish and paint. Waste water and dirt can be mentioned as other examples.

[0003] Although common positive displacement pumps can be used to convey the material to be conveyed, they cannot be analyzed. Especially in certain cases, the viscosity of the material to be conveyed is of concern. In the case of known solutions, samples of the material to be conveyed are taken during the downtime of the positive displacement pump in order to analyze the material to be conveyed. Subsequently, the samples are analyzed in the laboratory, for example to determine the viscosity of the material to be conveyed. This method is both time-consuming and laborious. Summary of the Invention

[0004] In view of the above situation, an object of the present invention is to provide a positive displacement pump that can analyze the material to be conveyed.

[0005] The positive displacement pump for conveying the material to be conveyed includes a measurement assembly having at least one measurement channel through which at least a part of the material to be conveyed pumped by the pump can flow. At least a part of the material to be conveyed pumped by the pump particularly corresponds to a part of the volume flow rate of the material to be conveyed pumped by the pump. At least a part of the material to be conveyed pumped by the pump can be referred to as a volume flow rate ratio, a volume ratio or a quantity ratio.

[0006] The at least one measurement channel has a non-circular cross-section. The cross-section is a section of the at least one measurement channel taken perpendicular to the flow direction of the at least one measurement channel. The cross-section (e.g., over the total length of the at least one measurement channel) can be constant in the flow direction of the at least one measurement channel.

[0007] The measurement assembly has a pressure sensor assembly for detecting the pressures acting at positions spaced apart along the flow direction of the at least one measurement channel when at least a part of the material to be conveyed pumped by the pump flows through the at least one measurement channel. These pressures can act from the inside of the at least one measurement channel to the outside. The measurement assembly or / and the pressure sensor assembly can particularly determine the pressure difference between two or more detected pressures.

[0008] Positive displacement pumps of this type can detect the pressure along a measurement channel having a non-circular cross-section. These pressures vary depending on the material to be conveyed, so that the material to be conveyed can be directly analyzed by means of the positive displacement pump. The non-circular cross-section of the measurement channel has proven to be particularly advantageous, as it ensures a flow profile in the measurement channel that is conducive to pressure measurement.

[0009] The cross-section of at least one measurement channel can include at least one straight segment. In this case, at least one measurement channel can include at least one flat side surface that forms at least one straight segment of the cross-section.

[0010] The at least one straight segment can lead with one of its ends to a corner of the cross-section or with both of its ends to respective corners of the cross-section. Such corners can form an angle between 10° and 170°, for example between 45° and 135°, in particular a 90° angle.

[0011] In one example, the cross-section is polygonal. In each case, the corners can be formed by two of the at least one straight segment. The cross-section can be polygonal, whereby each side of the polygon corresponds to one of the at least one straight segment.

[0012] The cross-section can be rectangular. Each of the four sides of the rectangular cross-section can correspond to one of the at least one straight segment.

[0013] The pressure sensor assembly is configured to detect, for example, the pressure acting from the inside of at least one measurement channel onto the sensor surface (e.g., outwards). For this purpose, the pressure sensor assembly can have a pressure sensor that detects the pressure acting on the sensor surface. A separate sensor surface and a separate pressure sensor can be provided for each pressure to be detected.

[0014] The sensor surface can form part of the cross-section of the measurement channel. The sensor surface can be formed to be substantially flat. The sensor surface particularly forms one of the at least one straight segment of the cross-section. Thus, the sensor surface can form a flat part of the side wall of at least one measurement channel. In an alternative design, the sensor surface can be designed to be curved. In this case, the sensor surface can form a curved segment of the cross-section. The sensor surface can extend over a part of the length of at least one measurement channel in the flow direction of the at least one measurement channel. This type of design of the sensor surface can reduce turbulence and flow deflection in the measurement channel, thus providing a more reliable pressure measurement.

[0015] According to one example, the height of the cross-section is less than its width. In this case, the sensor surface can extend in the width direction of the cross-section. Thus, the sensor surface can extend, in particular, over the total width of the measurement channel.

[0016] The measuring assembly can include a flow straightener that is arranged upstream of at least one measurement channel in the flow path of the material to be conveyed that is conveyed by the pump. The flow straightener can be arranged directly in front of at least one measurement channel and is, in particular, connected to the at least one measurement channel. The flow straightener can form an inlet opening of the at least one measurement channel, and the inlet opening tapers in the flow-through direction. For example, the inlet opening can be circular so that it does not form a step with respect to the measurement channel in the flow-through direction.

[0017] At least one measurement channel and / or the flow straightener can be designed such that a laminar profile of the material to be conveyed is ensured in the measurement channel (e.g., within a specified delivery speed range of a positive displacement pump and / or within a predetermined viscosity range of the material to be conveyed), in particular, in the width direction and / or height direction of at least one measurement channel.

[0018] The at least one measurement channel can include a plurality of measurement channels, and in each case at least a portion of the material to be conveyed that is conveyed by the pump can flow through these measurement channels. The cross-sections of these measurement channels are, in particular, different. The surface areas of these cross-sections can be different. These cross-sections can be formed in the same geometric shape (e.g., rectangular), but can have different (e.g., scaled) dimensions of this geometric shape. Thus, it is conceivable to provide polygons of different sizes with the same side length ratio as the cross-section. The cross-section (e.g., rectangular) of the measurement channel can be different, in particular, in its height and can have the same width. In this case, the pressure sensor assembly is particularly used to detect the pressure in each measurement channel.

[0019] The measurement channels of the measuring assembly are, for example, fluidly connected in parallel. In this case, the measurement channels also differ in at least a portion of the material to be conveyed that can flow through the respective measurement channels and is conveyed by the pump. Thus, a different volume flow ratio of the material to be conveyed that is to be conveyed by the pump can be assigned to each measurement channel.

[0020] The measuring assembly may include components in which each of at least one measuring channel is formed. The components may be integrally formed. The components are made of, for example, a ceramic material to ensure high wear resistance. Alternatively or additionally, the flow straightener may be made of a ceramic material. The measuring channels may be included in the component (e.g., by milling, punching, or sawing). It is also conceivable that the component is formed with internal measuring channels. The component may be substantially cylindrical and may extend along the flow direction of at least one measuring channel. The component may have recesses that extend radially and are spaced apart from each other in the flow direction, which are used to accommodate the pressure sensors of the pressure sensor assembly. Two or more recesses may be provided for each measuring channel. The recesses may be formed as through-holes that penetrate the corresponding measuring channels. In this case, the sensor surface may be part of the pressure sensor inserted into the recess.

[0021] The component may be wrapped by a tubular housing (which may be referred to as a housing tube). The component or / and the housing tube may be formed such that the virtual outer shell of the component or / and the housing tube is concave-curved in the flow direction. In other words, the component or / and the housing tube may be formed to be convex. The housing tube may include heat sinks to passively control the temperature of the material to be conveyed in the measuring channels. Heating devices or / and cooling devices may be provided, which are configured to ensure a defined temperature of the housing, the component, or / and the material to be conveyed in the measuring channels.

[0022] The flow directions of the measuring channels may be parallel to each other. Alternatively or additionally, it may be provided that the width directions of the cross-sections of the measuring channels extend obliquely to each other. In particular, it may be provided that at least one straight segment of each measuring channel cross-section is radially aligned outwardly based on a common axis (e.g., the longitudinal axis of the component). The outer sides of the cross-section (e.g., the width sides) may be arranged tangentially based on a virtual circle or may each be at the same distance from a reference point (e.g., a point on the longitudinal axis of the component).

[0023] According to a second aspect, a pump system is provided. The pump system includes a positive displacement pump according to the first aspect and a control unit. The control unit is configured to determine the viscosity of the material to be conveyed or / and the delivery speed (e.g., the provided volume flow rate) of the positive displacement pump based on the pressure detected by the pressure sensor assembly.

[0024] The control unit may be designed to classify the viscosity as viscoplastic, shear-thinning, shear-thickening, Newtonian, or Bingham fluid. The control unit may be designed to determine based on the pressure detected by the pressure sensor assembly whether the material to be conveyed is a material with or without viscosity-dependent shear rate and / or a material with or without flow limitation. For this purpose, the viscosity values of a plurality of measuring channels may be determined, which may also be referred to as viscosity multi-point measurement.

[0025] The control unit can be configured to determine the delivery speed of the positive displacement pump based on the pump speed of the positive displacement pump and / or the pump control signal of the positive displacement pump, in particular based on a known pump characteristic curve of the positive displacement pump, and to determine the viscosity of the material to be delivered based on the delivery speed determined in this way and the pressure detected by the pressure sensor assembly. The viscosity can also be determined as a function of at least one parameter, such as shear rate and / or temperature.

[0026] The control unit is in particular configured to perform one or more of the following steps: outputting the value of the determined delivery speed and / or the value of the determined viscosity; detecting wear of the positive displacement pump based on the determined delivery speed and / or viscosity; detecting slip of the positive displacement pump based on the determined delivery speed and / or viscosity; controlling the positive displacement pump based on the determined delivery speed and / or viscosity; controlling a viscosity regulating device based on the determined delivery speed and / or viscosity to regulate the viscosity of the material to be delivered; controlling a processing device for processing the material to be delivered based on the determined delivery speed and / or viscosity. Description of the Drawings

[0027] Embodiments of the present invention will be described in more detail below with reference to the drawings, in which:

[0028] Figure 1 shows a schematic diagram of a pump system;

[0029] Figure 2 shows a perspective view of a measurement assembly;

[0030] Figure 3 shows a longitudinal section of the measurement assembly;

[0031] Figure 4 shows a cross-section of a measurement channel;

[0032] Figure 5 shows a cross-section of a component having a plurality of measurement channels;

[0033] Figure 6 shows a first exemplary fluid interconnect; and

[0034] Figure 7 shows a second exemplary fluid interconnect. Detailed Description

[0035] Figure 1 shows a schematic diagram of a pump system 2. The pump system 2 includes a positive displacement pump 4 and a control unit 6 communicatively connected to the positive displacement pump 4. The control unit 6 can be mechanically fixed to the pump 4 or can be provided separately from the pump 4.

[0036] The positive displacement pump 4 can be an eccentric screw pump, although it can also be other types of positive displacement pumps. The positive displacement pump 4 is configured to convey a free-flowing filling material 8 - such as, in particular, varnish, oil or a suspension (such as waste water) - from a filling material reservoir 10 to a filling material container 12.

[0037] The positive displacement pump 4 includes a measurement assembly 14. In the example shown, the measurement assembly 14 is located in the downstream region of the pump 4. Alternatively, the measurement assembly 14 can also be arranged in the upstream region, as indicated by reference numeral 13. In any case, the measurement assembly 14 includes at least one measurement channel 16 and a pressure sensor assembly 18 having pressure sensors 20, 22. In the example shown, two pressure sensors are provided for the measurement channel 16, although it is also conceivable to provide three, four or more pressure sensors for the measurement channel 16.

[0038] At least a portion of the material 8 to be conveyed by the pump 4 can flow through the measurement channel 16. The pressure sensors 20, 22 are spaced apart from each other (e.g., the distance L from the center of the sensor to the center of the sensor) in the flow direction 24 of the measurement channel 16 and can detect the pressure at corresponding positions inside the measurement channel 16. This pressure can be detected as an absolute pressure or a differential pressure (e.g., based on a predetermined reference pressure, in particular based on the atmospheric pressure in the area around the pump 4).

[0039] The measurement assembly 14 can include other sensors, in particular a temperature sensor for detecting the temperature of the material to be conveyed by the pump 4. It is conceivable that the measurement assembly 14 has one or more temperature sensors for each measurement channel 16 for detecting the temperature of the material to be conveyed passing through the respective measurement channel 16. The temperature measurement values of these temperature sensors can be used, for example, to detect shear heat generation. A heating device or / and a cooling device 7 can be provided, which is configured to ensure a defined temperature of the housing of the pump system 2, of the components of the pump system 2 or / and of the material to be conveyed in the measurement channel 16.

[0040] The measurement assembly can also have a flow straightener 23, which is arranged upstream of at least one measurement channel 16 and is used to achieve a desired (e.g., laminar) flow profile of the material to be conveyed in the measurement channel 16. In the simplest case, the flow straightener forms a funnel-shaped inlet of the measurement channel 16 and can be made particularly of wear-resistant material (such as ceramic).

[0041] Figure 1An optional viscosity regulating device 26 is also proposed. It can regulate the viscosity of the material to be conveyed, for example by adding a diluent or a thickener, by controlling the temperature of the material to be conveyed or / and by adjusting the particle size distribution of the material to be conveyed (for example, by grinding the particles contained in the material to be conveyed). In addition, an optional processing device 28 is proposed, which is configured to use the material 8 to be conveyed pumped by the pump 4 during production or / and processing. The processing device 28 can be, for example, a coating device for applying varnish, especially for producing multi-layer battery cells.

[0042] The control device 6 is designed to determine the viscosity of the material to be conveyed and / or the delivery rate of the positive displacement pump based on the pressure detected by the pressure sensor assembly. The viscosity can be determined based on the pressure difference of the pressure detected by the pressure sensors 20, 22 when flowing through the measurement channel 16, based on the volume flow rate flowing through the measurement channel 16, and based on the known geometry of the measurement channel. In the example shown, the entire volume flow rate of the material to be conveyed pumped by the pump 4 is guided through the measurement channel 16. Therefore, the volume flow rate through the measurement channel 16 is directly determined by the delivery rate of the positive displacement pump. The control unit 6 can be designed to determine this delivery rate based on the pump speed of the positive displacement pump 4 and / or the pump control signal of the positive displacement pump 4, especially based on the known pump characteristic curve of the positive displacement pump 4. Especially when it is assumed that the material to be conveyed is incompressible, there is no need to provide a separate volume flow rate measurement to determine the viscosity.

[0043] Based on the determined delivery rate and / or the determined viscosity, the control unit 6 can output corresponding values (for example, output to a screen or a data processing device). The determined delivery rate and / or viscosity can also be further processed by the control unit 6.

[0044] If it can be assumed, for example, that the viscosity is constant, but the pressure values detected by the sensors 20, 22 change within a certain period of time, it can be concluded that the delivery rate of the delivery pump has decreased. If the pump 4 is controlled with the same control signal (for example, pump frequency) during this period, the control unit 6 can conclude that the currently used pump 4 is worn or / and the slip of the pump 4 has increased. Then, the control unit 6 can output a warning or readjust the pump 4 until the pressure value falls within the desired range again, which corresponds to the desired volume flow rate with a known constant viscosity.

[0045] Conversely, if it can be assumed that the delivery speed of the determined pump 4 is constant, but the pressure values detected by the sensors 20, 22 change over a certain period of time, it can be concluded that the viscosity of the material 8 to be delivered has changed. In particular, the temperature of the material 8 to be delivered can be considered here, for example, to determine whether the change is only related to the temperature or there are other reasons. Then, the control unit 6 can output a warning or control the viscosity regulating device 26 to adjust the viscosity towards the desired value. Alternatively or additionally, the control unit 6 can inform the processing device 28 of the viscosity change so as to adjust the manufacturing process accordingly.

[0046] The pressure values can be analyzed over time to detect undesired pulsations of the pump 4, especially after the pump is started. Then, the control unit 6 can readjust the pump 4 accordingly to minimize such pulsations. In the case of an eccentric screw pump, the control or readjustment of the pump 4 can include, for example, adjusting the stator position of the pump 4.

[0047] During the operation of the pump 4, i.e., when the measurement channel 16 is being flowed through, a pressure drop occurs in the flow direction of at least one measurement channel 16. This pressure drop can occur linearly, especially along the flow direction. Therefore, the two pressure sensors 20, 22 detect different magnitudes of pressure generated by the material 8 to be delivered in the measurement channel 16. In particular, the viscosity of the material 8 to be delivered can be determined based on this pressure difference. The following formula applies:

[0048]

[0049] where η represents the viscosity as a function of the shear stress σ and the shear rate Given the channel geometry coefficient K of the measurement channel 16, the viscosity η is a function of the pressure difference Δp between the two pressure values detected by the pressure sensors 20, 22 and the volume flow rate flowing through the channel 16:

[0050]

[0051] Figure 2 shows a perspective view of an exemplary measurement assembly 14. In this example, the measurement assembly 14 includes a substantially cylindrical member 30 in which a measurement channel 16 is formed. Both the measurement channel 16 and the member 30 extend along the flow direction 24. In Figure 2 it, the member 30 is embedded in the housing tube 32, although this does not necessarily have to be the case.

[0052] Figure 3 shows a longitudinal section through the exemplary measurement assembly 14 along the flow direction 24. In this example, there is no housing tube 32, so the member 30 is not enclosed. From Figure 3As can be seen, each sensor has sensor surfaces 34, 36 which laterally delimit the measurement channel 16. These sensor surfaces 34, 36 are spaced apart from each other in the flow direction 24, and each sensor surface extends only in the flow direction 24 over a part T 1 or T 2 of the length of the measurement channel 16. In the example shown, the sensor surfaces 34, 36 are relatively large compared to the height h of the measurement channel 16 (T 1 > h, T 2 > h). Thus, a relatively high shear rate can be provided in the measurement channel 16. For example, if a lower shear rate is required, it is also conceivable to design the measurement channel 16 with different dimensions (T 1 = h or T 1 < h; or / and T 2 = h or T 2 < h). The centers of the respective sensor surfaces 34, 36 are offset by a distance L in the flow direction 24.

[0053] At least one measurement channel 16 has a non-circular cross-section 38, in particular a cross-section having one or more straight segments 39. The sensor surfaces 34, 36 can thereby form one of these straight segments. Figure 4 An example of such a non-circular cross-section 38 of at least one measurement channel 16 is shown. In this example, the cross-section 38 is rectangular, having a height h which is less than the width a. In the width direction of the cross-section 38 of the measurement channel 16, flat (e.g., also rectangular or circular) sensor surfaces 34 and 36 extend over their entire width and form its top side.

[0054] In the case of the cross-section 38, the following formula applies to the channel geometry coefficient K of the measurement channel 16:

[0055]

[0056] In this case, based on the pressure difference Δp and the volume flow rate the viscosity of the material 8 to be conveyed is:

[0057]

[0058] Thus, in the case of a known volume flow rate, the viscosity can be calculated based on the detected pressure, and in the case of a known viscosity, the volume flow rate can be calculated based on the detected pressure. The same applies in the case of other channel geometries, so that the channel geometry coefficient K may deviate from formula 3.

[0059] At least one measurement channel 16 may include a plurality of measurement channels 16-1, 16-2... 16-n. In other words, the measurement assembly 14 may include a plurality of correspondingly formed measurement channels 16. The measurement channels may differ from one another, in particular with respect to their cross-sections 38-1, 38-2... 38-2n. Accordingly, the respective values of the pressure difference Δp for different channel cross-sections can be determined. From this, the respective viscosity values of the material to be conveyed can be determined for each measurement channel. By comparing these viscosity values, the control unit 6 can draw conclusions about the viscosity of the material to be conveyed (which is a function of the shear rate), and in particular can determine whether the material to be conveyed is shear-thinning or shear-thickening.

[0060] Figure 5 An exemplary arrangement of a plurality of measurement channels 16-1, 16-2, 16-3 is shown, all of which are formed in the same component 30 and have parallel flow-through directions. The measurement channels 16-1, 16-2, 16-3 each have a rectangular cross-section 38-1, 38-2, 38-3 here. Although the width a of the cross-section is the same, their heights h1, h2, h3 are different.

[0061] For each measurement channel 16-1, 16-2, 16-3, corresponding pressure sensors are provided with sensor surfaces 34-1, 34-2, 34-3 and 36-1, 36-2, 36-3. The sensor surfaces here also form the respective top sides of the corresponding measurement channels. Thereby, the sensor surfaces are aligned radially outwards based on the longitudinal axis 38 of the component 30 extending in the flow-through direction. Thus, the pressure sensors can be fixed to the component 30 from different directions to measure the pressure in channels of different sizes.

[0062] The measurement channels 16-1, 16-2, 16-3 can be connected to one another in fluid series or in parallel. Figure 6 A corresponding series connection is shown schematically, Figure 7 and a parallel connection is shown. In the series connection, the same volume flow can flow through each measurement channel 16-1, 16-2, 16-3. In contrast, in the parallel connection, the volume flow is divided into three shunts and each shunt flows through a different one of the measurement channels 16-1, 16-2, 16-3.

[0063] It goes without saying that only one, only two, four or more measurement channels 16 instead of three measurement channels can be provided. These measurement channels can be connected in parallel in groups and / or in series in groups. One or more of the measurement channels 16 can be arranged upstream of the eccentric screw pump, and one or more of the measurement channels 16 can be arranged downstream of the eccentric screw pump. It is also conceivable to use another pump (for example, with a greater delivery capacity) in parallel with the pump 4 to convey the material to be conveyed from the filling material reservoir 10 to the filling material container 12. The measuring assembly 14 can be arranged outside the pump housing of the positive displacement pump 4, for example, in a pipeline system that is fluidly connected to the positive displacement pump 4. Those skilled in the art can obtain other advantages and modifications from the current disclosure.

Claims

1. A positive displacement pump (4) for conveying a material (8) to be conveyed, comprising a measuring assembly (14), the measuring assembly (14) having at least one measuring channel (16, 16-1, 16-2, 16-3), through which at least a portion of the material (8) to be conveyed conveyed by the pump (4) can flow, wherein the at least one measuring channel (16, 16-1, 16-2, 16-3) has The measuring assembly (14) has a non-circular cross section (38, 38-1, 38-2, 38-3), and the measuring assembly (14) has a pressure sensor assembly (18) for detecting the pressure acting at positions spaced apart along the flow direction (24) of the at least one measuring channel (16, 16-1, 16-2, 16-3) when at least a portion of the material to be conveyed (8) conveyed by the pump (4) flows through the at least one measuring channel (16, 16-1, 16-2, 16-3).

2. The positive displacement pump (4) according to claim 1, wherein: The cross section (38, 38-1, 38-2, 38-3) of the at least one measuring channel (16, 16-1, 16-2, 16-3) comprises at least one straight line segment (39).

3. The positive displacement pump (4) according to claim 2, wherein: The cross section (38, 38-1, 38-2, 38-3) is polygonal.

4. The positive displacement pump (4) according to claim 2, wherein: The cross section (38, 38-1, 38-2, 38-3) is rectangular, and each of the four sides of the rectangular cross section (38, 38-1, 38-2, 38-3) corresponds to one of the at least one straight line segment (39).

5. The positive displacement pump (4) according to claim 3, wherein: The cross section (38, 38-1, 38-2, 38-3) is rectangular, and each of the four sides of the rectangular cross section (38, 38-1, 38-2, 38-3) corresponds to one of the at least one straight line segment (39).

6. A positive displacement pump (4) according to any one of claims 2 to 5, wherein: The pressure sensor assembly (18) is configured to detect pressure acting on a sensor surface (34, 36) from within the at least one measuring channel (16, 16-1, 16-2, 16-3), wherein the sensor surface (34, 36) forms one of at least one straight line segments (39) of the cross-section (38, 38-1, 38-2, 38-3) and extends over a portion of the length of the at least one measuring channel (16, 16-1, 16-2, 16-3) in its flow direction (24).

7. The positive displacement pump (4) according to claim 6, wherein: The height (h, hi, h2, h3) of the cross section (38, 38-1, 38-2, 38-3) is smaller than its width (a), and wherein the sensor surface (34, 36) extends in the width direction of the cross section (38, 38-1, 38-2, 38-3).

8. A positive displacement pump (4) according to any one of claims 1 to 5, wherein: The at least one measuring channel (16, 16-1, 16-2, 16-3) comprises a plurality of measuring channels (16-1, 16-2, 16-3) through which at least a portion of the material to be conveyed (8) conveyed by the pump (4) can flow in each case, wherein the cross sections (38-1, 38-2, 38-3) of the measuring channels (16-1, 16-2, 16-3) are different.

9. The positive displacement pump (4) according to claim 8, wherein: The measuring channels (16-1, 16-2, 16-3) are fluidically connected in parallel, and the measuring assembly (14) comprises a component (30) in which each of the measuring channels (16-1, 16-2, 16-3) is formed.

10. The positive displacement pump (4) according to claim 8, wherein: The flow directions (24) of the measuring channels (16-1, 16-2, 16-3) extend parallel to each other or / and the width directions of the cross sections (38-1, 38-2, 38-3) of the measuring channels (16-1, 16-2, 16-3) extend obliquely to each other.

11. The positive displacement pump (4) according to claim 9, wherein: The flow directions (24) of the measuring channels (16-1, 16-2, 16-3) extend parallel to each other or / and the width directions of the cross sections (38-1, 38-2, 38-3) of the measuring channels (16-1, 16-2, 16-3) extend obliquely to each other.

12. A pump system (2) comprising a positive displacement pump (4) according to any one of claims 1 to 11 and a control unit (6), the control unit being configured to determine the viscosity of the material to be conveyed (8) or / and the conveying speed of the positive displacement pump (4) based on the pressure detected by the pressure sensor assembly (18).

13. The pump system (2) according to claim 12, wherein: The control unit (6) is configured to determine the delivery speed of the positive displacement pump (4) based on the pump speed of the positive displacement pump (4) or / and the pump control signal of the positive displacement pump (4), and to determine the viscosity of the material to be delivered (8) based on the delivery speed determined in this way and the pressure detected by the pressure sensor assembly (18).

14. The pump system (2) according to claim 13, wherein: The control unit (6) is configured to determine a delivery speed of the positive displacement pump (4) based on a known pump characteristic curve of the positive displacement pump (4).

15. The pump system (2) according to any one of claims 12 to 14, wherein: The control unit (6) is further configured to perform one or more of the following steps: outputting the determined value of the conveying speed and / or the determined value of the viscosity; Detecting wear of the positive displacement pump (4) based on the determined delivery speed and / or viscosity; Detecting slip of the positive displacement pump (4) based on the determined delivery rate and / or viscosity; controlling the positive displacement pump (4) based on the determined delivery rate and / or viscosity; Controlling the viscosity regulating device (26) based on the determined conveying speed and / or viscosity to regulate the viscosity of the conveyed material (8); A processing device (28) for processing the conveyed material (8) is controlled based on the determined conveying speed and / or viscosity.

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