Field device for process automation

Abstract

The invention relates to a field device (1) for process automation, comprising: - a measuring tube (2) for conveying a flowable medium; - a sensor (3) for determining a physical and / or chemical measuring variable; - a plastic housing (4) for protecting the sensor (3), wherein the plastic housing (4) comprises separate housing parts (30, 31), wherein the plastic housing (4) comprises a housing interior (4) in which at least a part of the sensor (3) is arranged; - a heating device (5), characterized in that, by means of the heating device (5), an integral fusion bond is produced between the individual housing parts (30, 31) of the plastic housing (4), between the plastic housing (4) and the measuring tube (2) and / or between the plastic housing (4) and a transmitter housing (6).

Description

Technical Field

[0001] This invention relates to field equipment for determining process variables of flowable media in process automation. Background Technology

[0002] In automation, particularly process automation, field devices are frequently used to capture and / or modify process variables. To detect process variables, sensors integrated into devices such as fill level measuring devices, flow meters, pressure and temperature measuring devices, pH-redox potentiometers, conductivity meters, etc., are used to detect the corresponding process variables, such as fill level, flow rate, pressure, temperature, pH level, or conductivity. Actuators, such as valves or pumps, are used to influence process variables. Thus, the flow rate of fluid in a pipeline section or the fill level in a container can be changed by actuators. In principle, all devices oriented towards the process and providing or processing process-related information are referred to as field devices. Therefore, in conjunction with this invention, "field device" also refers to remote I / O, radio adapters, or generally refers to electronic measuring components located at the field level.

[0003] Specifically, the field equipment is selected from a group consisting of flow meters, filling level measuring devices, pressure measuring devices, temperature measuring devices, limit level measuring devices, and / or analytical measuring devices.

[0004] Flow meters, especially Coriolis, ultrasonic, eddy current, thermal and / or magnetic induction flow meters.

[0005] Filling liquid level measuring equipment, especially radar-based filling liquid level measuring equipment, microwave filling liquid level measuring equipment, ultrasonic filling liquid level measuring equipment, time domain reflectance measurement filling liquid level measuring equipment, radiation measurement filling liquid level measuring equipment, capacitance filling liquid level measuring equipment, inductive filling liquid level measuring equipment and / or temperature-sensitive filling liquid level measuring equipment.

[0006] Fill level measuring devices are especially absolute, relative, or differential pressure devices.

[0007] Temperature measuring equipment, especially measuring equipment with thermocouples and / or temperature-dependent resistors.

[0008] Limiting liquid level measuring devices are particularly electronic vibration limiting liquid level measuring devices, ultrasonic limiting liquid level measuring devices, and / or capacitive limiting liquid level measuring devices.

[0009] Analytical measurement devices are in particular pH sensors, conductivity sensors, oxygen and reactive oxygen species sensors, (spectro)photometric sensors and / or ion-selective electrodes.

[0010] EP 1 696 214 A1 discloses a flow meter for measuring the velocity of a flowing medium, comprising a measuring tube made of plastic for conducting the medium and a connecting device for connecting one end of the measuring tube to one end of a pipe made of plastic. The connecting device is a heating device in the form of a heating wire integrated into the inner wall of the measuring tube or into a connecting sleeve. When the heating wire is heated, the inner wall partially melts at the connection point between the measuring tube and the connecting body or between the measuring tube and the pipe, thereby creating a fusion bond.

[0011] DE 10 2013 102 544 A1 also discloses a plastic measuring tube having a magnetic system adapter for attaching a magnetic system. The adapter includes a heating line capable of being heated, which allows partial melting of the adapter material. This ensures that the adapter is integrally fixed to the plastic measuring tube. This type of fixing allows for quick, adaptable, and reliable integral bonding.

[0012] The purpose of this invention is to further develop known solutions. Summary of the Invention

[0013] This objective is achieved by the field device according to claim 1.

[0014] The field device for process automation according to the present invention includes: - A measuring tube used to convey flowable media; - Sensors used to determine physical and / or chemical measurement variables. - A plastic housing for protecting the sensor. The plastic shell includes a separate shell portion. The plastic housing includes an interior, and at least a portion of the sensor is disposed within the interior of the housing. - Heating equipment, The feature is that, through the heating device, an integral fusion bond is formed between the various housing parts of the plastic housing, between the plastic housing and the measuring tube, and / or between the plastic housing and the transmitter housing.

[0015] Unlike EP 1 696 214 A1 and DE 10 2013 102 544 A1, the subject matter of this invention does not require the measuring tube and conduit or the measuring tube and magnetic system adapter to be connected to each other via a heating device. Instead, the various housing portions of the plastic housing are fused together with each other, to the measuring tube or to the transmitter housing. However, the possibility that other components of the field equipment may also be secured in place using heating devices is not excluded.

[0016] Advantageous embodiments of the present invention are the subject of the dependent claims.

[0017] One embodiment specifies that the measuring tube comprises a plastic measuring tube.

[0018] One embodiment specifies that the measuring tube includes a carrier tube, the carrier tube including at least a sub-region in which the carrier tube is coated with a plastic coating. The overall fusion bonding is located in the coated sub-region.

[0019] This has the following advantages: the application of the heating device is not limited to measuring tubes made purely of plastic. The carrier tube can be, for example, a metal tube (especially a steel tube), a ceramic tube, or a glass tube. The carrier tube can be fully coated on its outer surface, or alternatively, coated only at the point where the plastic housing contacts the measuring tube.

[0020] One embodiment specifies that the plastic housing includes a first half-shell and a second half-shell. The heating device is used to create an integral fusion between the first half-shell and the second half-shell.

[0021] The first and second half-shells may be arranged radially relative to the measuring tube, or pushed axially relative to the measuring tube. The first and second half-shells form the housing portion, which is joined to each other by fusion bonding, thereby forming the plastic housing.

[0022] One embodiment specifies the triple point where the first half-shell, the second half-shell, and the measuring tube meet. The three-phase point is at least selectively sealed by the overall fusion bonding.

[0023] The triple point is the point where the three components (in this case, the measuring tube, the first half-shell, and the second half-shell) come together. Due to tolerances, gaps may form at the triple point, which subsequently requires complex sealing. This is not necessary if the individual components are joined using an integral fusion bond produced by the heating device. This causes the material of the half-shell and / or the measuring tube to melt at the triple point, thereby sealing it.

[0024] One embodiment specifies that the transmitter housing comprises a plastic transmitter housing, and the measuring and / or communication electronics are arranged within the plastic transmitter housing. The heating device forms an integral fusion bond between the plastic transmitter housing and the plastic housing.

[0025] One embodiment specifies that the transmitter housing comprises a plastic transmitter housing, and the measuring and / or communication electronics are arranged within the plastic transmitter housing. The plastic housing has a connector for the transmitter housing, particularly the plastic transmitter housing. The connector is arranged between the plastic transmitter housing and the plastic housing to connect them. The heating device forms an integral fusion bond between the connector and the plastic housing and / or between the connector and the plastic transmitter housing.

[0026] One embodiment specifies that the plastic housing includes a first collar and a second collar. The plastic shell includes a cover. The first collar and the second collar restrict the interior of the housing in the axial direction of the measuring tube. The sleeve restricts the interior of the housing in the radial direction of the measuring tube. The heating device enables an integral fusion bond to be formed between the housing and at least the first collar (particularly the first collar and the second collar).

[0027] One embodiment specifies that the heating device has a heating element disposed between the measuring tube and the plastic housing, and / or

[0028] The heating device has a heating element disposed between the plastic housing and the connector, and / or

[0029] The heating device has a heating element disposed between the connector and the plastic transmitter housing, and / or

[0030] The heating device has a heating element disposed between the plastic housing and the plastic transmitter housing.

[0031] One embodiment specifies that the heating device has a heating element, which is integrally arranged within the housing body of the plastic housing, and / or

[0032] The heating device includes a heating element, which is integrally arranged within the connector body of the connector, and / or

[0033] The heating device has a heating element, which is integrally arranged in the transmitter housing body of the plastic transmitter housing.

[0034] The plastic material is cast around the heating element during the manufacturing process of the plastic housing, its housing portion, the connector body, or the transmitter housing body. This ensures that the heating element is integrally formed in the corresponding component. The heating element can be connected to a voltage source via a contact device of the heating device, including an electrical connection. When a voltage is applied to the heating element, it heats up. If the temperature of the heating element rises above the melting point of the plastic, the plastic begins to melt. When the plastic has cooled and hardened, a monolithic fusion bond is formed. This type of bond is not only very strong but also liquid and gas-tight. This is particularly advantageous in applications where the plastic housing is exposed to weather.

[0035] One embodiment specifies that the heating element includes a heating film or a heating wire.

[0036] The heating wire is supplied, for example, by Orbi-Tech. The heating wire is a resistance wire, such as a metal resistance wire, radially surrounded by a plastic sleeve made of polyethylene or polypropylene. The heating film is a plastic film in which resistance wires, wound or structurally formed (e.g., metal), are integrally arranged.

[0037] One embodiment specifies that the integral fusion bond is formed by heating with the heating device and partially melting the measuring tube and / or the plastic housing and / or the plastic transmitter housing.

[0038] One embodiment specifies that the connection is designed to seal the interior of the housing outwards.

[0039] One embodiment specifies that the field device used for process automation is an electromagnetic flowmeter. The sensor has at least two measuring electrodes and a device for generating a magnetic field. Attached Figure Description

[0040] The invention will be explained in more detail with reference to the following figures. In the figures: Figure 1 The longitudinal and cross sections of a first embodiment of the field device according to the present invention are shown. Figure 2 The longitudinal and cross sections of a second embodiment of the field device according to the present invention are shown. Figure 3 A longitudinal section of a third embodiment of the field device according to the present invention is shown; Figure 4 : is a perspective view of a longitudinal section of a fourth embodiment of the flowmeter according to the present invention; and Figure 5: is a perspective view of a longitudinal section of a field device according to a fifth embodiment of the present invention. Detailed Implementation

[0041] Some embodiments of this disclosure will now be described in more detail with reference to the accompanying drawings. The drawings illustrate some, but not all, embodiments of this disclosure. In fact, this disclosure can be embodied in many different forms and should not be construed as limited to the embodiments presented herein. Each different embodiment illustrating various details of the subject matter of the invention can be combined with one another to form new embodiments not shown in the drawings. The same numerals always refer to the same elements.

[0042] The components shown in the accompanying drawings represent components that may or may not be present in the various embodiments of this disclosure described herein, and therefore, embodiments may include fewer or more components than those shown in the drawings without departing from the scope of this disclosure. Some components may be omitted or depicted by dashed lines in one or more drawings to reveal components located below them.

[0043] In exemplary embodiments, expressions such as "some embodiments," "various embodiments," etc., generally mean that a particular feature, structure, or property following that expression may be included in at least one embodiment of this disclosure, and may be included in more than one embodiment of this disclosure. Such expressions do not necessarily have to refer to the same embodiment.

[0044] The terms “example” or “exemplary” are used herein in the sense of “serving as an example or illustration.” Each embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0045] If the description in the accompanying drawings states that a component, portion, or feature is "preferred," "possibly," "generally," or "optionally" included or is included "for example" (or any other such expression), or that a feature "may" be included, or that a feature "may" or "should" have an attribute, then the inclusion of a particular component or feature is not mandatory. Optionally, such components or features may be included in some embodiments, but they may also be excluded. Embodiments not included in the drawings may also include all the features of the illustrated embodiments, provided they do not contradict each other.

[0046] Figure 1 A longitudinal and cross-sectional view of a first embodiment of a field device 1 according to the present invention is shown. The field device 1 includes a measuring tube 2 for conveying a flowable medium. The measuring tube 2 may have a circular or square cross-section. In the case of a square cross-section, the corners may be rounded. The measuring tube 2 shown is made of a plastic material. The measuring tube 2 may be made entirely of plastic material, or it may additionally include fiber composite materials to increase its load-bearing capacity.

[0047] To determine physical and / or chemical measurement variables, the field device 1 has a sensor 3. These physical and / or chemical measurement variables can be, for example, flow rate, volumetric flow rate, mass flow rate, pressure, temperature, density, pH value, electrolytic conductivity, filling level, concentration, degree of fermentation, or viscosity of the culture medium. The sensor 3 itself can be a pH probe, conductivity probe, temperature sensor, or pressure sensor. Alternatively, the sensor 3 may also include components necessary for determining flow rate, volumetric flow rate, mass flow rate, and / or viscosity. Therefore, the sensor 3 may include at least two measuring electrodes and a magnetic system to determine the flow rate of the delivered medium based on Faraday's law of electromagnetic induction. Alternatively, the sensor 3 may include at least two ultrasonic transducers spaced apart from each other in the flow direction, configured to determine the flow rate or the variable of the medium derived therefrom based on time-of-flight measurements. Alternatively, the sensor 3 may include a vibration exciter and one or two vibration sensors, collectively configured to determine the mass flow rate and / or viscosity based on the vibration behavior of the measuring tube 2. Alternatively, sensor 3 may include a blade extending into a measuring channel of the measuring tube, which is used to determine the flow velocity or the variable of the flow medium derived therefrom.

[0048] The field device 1 shown includes a plastic housing 4 for protecting the sensor 3, which is disposed on the outer surface of the measuring tube and encloses at least a portion of the sensor 3. The plastic housing 4 has separate housing portions 30, 31, which, when assembled, form the plastic housing 4 and enclose the interior of the housing 4. The housing portions 30 and 31 may be, for example, at least two half-shells arranged radially on the outer surface of the measuring tube. The sensor 3 is at least partially disposed inside the housing 4. This means that the entire sensor 3 can be located inside the housing 4. Alternatively, an opening extending through the plastic housing 4 may be provided, such that a portion of it lies within the housing 4. In the middle, while another part is located inside the shell 4 In addition.

[0049] According to the invention, the field device 1 has a heating device 5 designed to create an integral fusion bond between the plastic housing 4 and the measuring tube 2 during the production of the field device 1. The heating device 5 heats the housing of the plastic housing 4, causing partial melting of the main body of the plastic housing 4. The molten portion of this housing body then bonds to the outer surface of the measuring tube 2. The measuring tube 2 may also be made of a plastic material selected such that it is also at least partially melted by the heating device. An improved fusion bond can even be achieved if both parts to be joined melt, rather than just one part.

[0050] The heating device 5 includes a heating element 17a, which can be arranged between the measuring tube 2 and the plastic housing 4 or can be integrally arranged in the plastic housing 4.

[0051] The housing portions 30 and 31 can be a first half-shell 10a and a second half-shell 10b. Therefore, an integral fusion bond produced by the heating device 5 will exist between the first half-shell 10a and the second half-shell 10b. A so-called triple point 11 is formed at the connection point between the first half-shell 10a and the second half-shell 10b and the measuring tube 2. A gap often forms at this connection point, requiring complex sealing. The triple point 11 can be at least selectively sealed by this integral fusion bond. The heating device 5 can be configured to melt the contact areas of the two half-shells 10a and 10b and / or the outer surface of the measuring tube 2, such that the heated material fills and seals the triple point 11.

[0052] Figure 2 A longitudinal section and a cross section are shown according to a second embodiment of the field device 1 according to the present invention. The second embodiment differs from the first embodiment in that the measuring tube 2 has a carrier tube 7 made of metal, glass, ceramic or plastic material and coated with a plastic coating 8 in at least a sub-region 9. The plastic coating 8 may be provided on the entire outer surface of the carrier tube 7 or may only cover at least one sub-region 9, in which the overall fusion bonding is also located.

[0053] Furthermore, the second embodiment differs from the first embodiment in that an integral fusion bond is formed between the plastic housing 4 and the measuring tube 2 by means of the plastic coating 8.

[0054] In addition to heating element 17a, heating device 5 also has heating element 17b, which can be arranged between components 30 and 31 of plastic housing 4, or can be integrally arranged in the edge region of one of components 30 and 31. Heating element 17b is designed to be heated after assembling components 30 and 31 or after positioning components 30 and 31 on measuring tube 2, so as to melt the corresponding edge regions of components 30 and 31 or the edge regions of at least two components 30 and 31, and thus create a fusion bond between the two components 30 and 31.

[0055] Figure 3 A longitudinal section of a third embodiment of the field device 1 according to the present invention is shown. The third embodiment differs from the first embodiment in that, in addition to the first collar 15a and the second collar 15b, the plastic housing 4 also has a sleeve 16, which, together with the first and second collars, forms the plastic housing 4 in the final assembled state. The first collar 15a and the second collar 15b restrict the interior 4 of the housing in the axial direction of the measuring tube 2. On the other hand, the housing 16 restricts the interior 4 of the housing in the radial direction of the measuring tube 2. The heating element 17b can be arranged between the first collar 15a and / or the second collar 15b and the housing 16. Alternatively, the heating element 17b can be integrated into the first collar 15a and / or the second collar 15b. Alternatively, the heating element 17b can also be integrated into the housing 16. The heating element 17b or multiple heating elements 17b are part of the heating device 5. The heating device 5 is designed to form an integral fusion bond between the individual housing parts (i.e., the first collar 15a, the second collar 15b, and / or the housing 16).

[0056] Figure 4 A perspective view of a longitudinal section of a fourth embodiment of the field device 1 according to the present invention is shown. The field device 1 shown is a magnetic flowmeter 20, whose sensor has at least two measuring electrodes 21, 22 and a device 23 for generating a magnetic field. The device 23 for generating a magnetic field may include at least one coil having a coil core, which is arranged on the outer surface of the measuring tube 2. The at least two measuring electrodes 21, 22 may be designed as capacitive electrodes, which are spaced from the medium by the tube wall of the measuring tube 2, or, as shown, the at least two measuring electrodes 21, 22 may be designed as current electrodes, each arranged in an opening of the measuring tube 2 and designed to contact the medium when the medium flows through the measuring tube 2 or when it is located in the measuring tube 2. The fourth embodiment may include details of the preceding three embodiments. However, the fourth embodiment shown differs from the foregoing embodiments at least in that an integral fusion bond is formed between the plastic housing 4 and the connector 14 by means of a heating device 5. The connector 14 serves as an intermediate part or as a transmitter housing (not shown; see Figure 5 ) adapters, measurement and / or communication electronics (not shown; see Figure 5 The connector 14 is arranged within the transmitter housing. The connector 14 is preferably made of plastic and has heating elements 17c and 17d integrated into the plastic body of the connector 14. Alternatively, heating element 17c may be arranged between the connector 14 and the plastic housing 4. Alternatively, heating element 17d may be arranged between the connector 14 and the transmitter housing. During assembly of the field device 1, heating element 17c is designed to create an integral fusion bond between the connector 14 and the plastic housing 4. During assembly of the field device 1, heating element 17d is designed to create an integral fusion bond between the connector 14 and the transmitter housing.

[0057] Figure 5A perspective view of a longitudinal section of a fifth embodiment of the field device 1 according to the present invention is shown. The fifth embodiment differs from the fourth embodiment in that the transmitter housing 6 is directly connected to the plastic housing 4. Similar to the fourth embodiment, no connecting element is provided. The transmitter housing 6 shown comprises plastic, in which measuring and / or communication electronics 13 are arranged within the transmitter housing 12. Since no connecting element is provided, a direct connection must be made between the plastic transmitter housings 12. Therefore, an integral fusion bond exists between the plastic transmitter housing 12 and the plastic housing 4, which is produced by means of a heating device 5. Therefore, the heating device 5 includes a heating element 17e, which can be arranged between the plastic housing 4 and the plastic transmitter housing 12, or can be integrated into the transmitter housing body 12′ of the plastic transmitter housing 12. Alternatively, the integral fusion bond can also be produced via a heating element (not shown) integrated into the plastic housing 4, particularly in the contact area that contacts the transmitter housing 6.

[0058] For all embodiments, heating elements 17a, 17b, 17c, 17d, and 17e may include a heating film 17 Alternatively, a heating wire 17′ may be used. The heating wire may be supplied, for example, by Orbi-Tech. The heating electrode is a resistance bar, such as a metal resistance bar, radially encapsulated by a plastic sleeve made of polyethylene or polypropylene. The heating film is a plastic film in which resistance wires wound or structurally formed (e.g., metal) are integrally arranged.

[0059] For all configurations, the fusion joint can be designed to seal the interior of the outer housing. .

Claims

1. A field device (1) for process automation, comprising: - A measuring tube (2) for conveying a flowable medium; - Sensors used to determine physical and / or chemical measurement variables (3); - A plastic housing (4) for protecting the sensor (3), The plastic shell (4) includes separate shell parts (30, 31). The plastic shell (4) includes the shell interior (4) At least a portion of the sensor (3) is arranged inside the housing (4). )middle; - Heating equipment (5), The feature is that, by means of the heating device (5), an integral fusion bond is formed between the various housing parts (30, 31) of the plastic housing (4), between the plastic housing (4) and the measuring tube (2), and / or between the plastic housing (4) and the transmitter housing (6).

2. The field device (1) for process automation according to claim 1, in, The measuring tube (2) includes a plastic measuring tube (2).

3. The field device (1) for process automation according to claim 1 or 2, in, The measuring tube (2) includes a carrier tube (7), which includes at least a sub-region (9) in which the carrier tube (7) is coated with a plastic coating (8). The overall fusion bonding is located in the coated sub-region (9).

4. The field device (1) for process automation according to any one of the preceding claims, in, The plastic shell (4) has a first half-shell (10a) and a second half-shell (10b). The heating device (5) creates an integral fusion bond between the first half-shell (10a) and the second half-shell (10b).

5. The field device (1) for process automation according to claim 4, in, The triple point (11) exists at the point where the first half-shell (10a), the second half-shell (10b), and the measuring tube (2) meet. The triple point (11) is at least selectively sealed by the overall fusion bond.

6. The field device (1) for process automation according to any one of the preceding claims, in, The transmitter housing (6) includes a plastic transmitter housing (12), in which measuring and / or communication electronics (13) are arranged. The heating device (5) creates an integral fusion bond between the plastic transmitter housing (12) and the plastic housing (4).

7. The field device (1) for process automation according to any one of claims 1 to 5, in, The transmitter housing (6) includes a plastic transmitter housing (12), in which measuring and / or communication electronics (13) are arranged. The plastic housing (4) has a connector (14) for the transmitter housing (6), particularly the plastic transmitter housing (12). The connector (14) is arranged between the plastic transmitter housing (12) and the plastic housing (4) to connect them. The heating device (5) enables an integral fusion bond to be formed between the connector (14) and the plastic housing (4) and / or between the connector (14) and the plastic transmitter housing (12).

8. The field device (1) for process automation according to any one of the preceding claims, in, The plastic shell (4) has a first collar (15a) and a second collar (15b). The plastic shell (4) includes a cover (16). Wherein, the first collar (15a) and the second collar (15b) restrict the interior (4) of the housing in the axial direction of the measuring tube (2). ), The housing (16) restricts the interior (4) of the housing in the radial direction of the measuring tube (2). ), In this process, the heating device (5) creates an integral fusion bond between the housing (16) and at least the first collar (15a), particularly with the first collar (15a) and the second collar (15b).

9. The field device (1) for process automation according to any one of the preceding claims, in, The heating device (5) has a heating element (17a) arranged between the measuring tube (2) and the plastic housing (4), and / or The heating device (5) has a heating element (17b) arranged between the components (30, 31) of the plastic housing (4), and / or The heating device (5) has a heating element (17c) disposed between the plastic housing (4) and the connector (14), and / or The heating device (5) has a heating element (17d) arranged between the connector (14) and the plastic transmitter housing (12), and / or The heating device (5) has a heating element (17e) arranged between the plastic housing (4) and the plastic transmitter housing (12).

10. The field device (1) for process automation according to any one of claims 1 to 8, in, The heating device (5) includes heating elements (17a, 17b), which are integrally arranged in the housing body (4') of the plastic housing (4), and / or The heating device (5) includes heating elements (17c, 17d), which are integrally arranged in the connector body (14') of the connector (14), and / or The heating device (5) has a heating element (17e), which is integrally arranged in the transmitter housing body (12′) of the plastic transmitter housing (12).

11. The field device (1) for process automation according to claim 9 or claim 10, in, The heating elements (17a, 17b, 17c, 17d, 17e) include a heating film (17... ) or heated welding wire (17′).

12. The field device (1) for process automation according to any one of the preceding claims, in, The integral fusion bond is formed by heating with the heating device (5) and partially melting the measuring tube (2) and / or the plastic housing (4) and / or the plastic transmitter housing (12).

13. The field device (1) for process automation according to any one of the preceding claims, in, The fusion joint is designed to seal the interior of the housing outwards (4) ).

14. The field device (1) for process automation according to any one of the preceding claims, in, The field device (1) for process automation is a magnetic flowmeter (20). The sensor (3) has at least two measuring electrodes (21, 22) and a device (23) for generating a magnetic field.

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