Coplanar differential pressure transducer

Abstract

The invention relates to a coplanar differential pressure transducer (1) comprising a measuring mechanism (2) and a transducer chamber (3), the measuring mechanism (2) having two process-facing separation diaphragms (5a, 5b). Two pressures (p1, p2) are applied to the separation diaphragms (5a, 5b), which are hydraulically transmitted via corresponding capillary systems (10a, 10b, 11a, 11b) to a pressure-sensitive measuring element (13) located in the transducer chamber (3). In the process-facing end region of the measuring mechanism, the measuring mechanism (2) is designed as a process connection (21) for a hardware interface (23a, 23b) of a customer connection (24a; 24b). In the process-facing end face of the main body (9) of the process connection (21), a disc-shaped recess (17) is provided in front of each of the two separation diaphragms (5a, 5b). Each of the two disc-shaped recesses (17) is in the form of two circles which intersect to form an elliptical structure and have different radii (Ra; Rb). Two insert discs (19a; 19b) are provided, which have openings (26a; 26b), correspond to the disc-shaped recesses (17), can be mounted in the disc-shaped recesses (17) and are designed such that the process connection (21) can be adapted to the hardware interface (23a; 23b) of the customer connection (24a; 24b).

Description

TECHNICAL FIELD

[0001] The present application relates to a differential pressure transducer of the coplanar type.

[0002] The differential pressure transducer according to the application is preferably used in the field of automation technology. BACKGROUND

[0003] The main components of a differential pressure meter are a measuring cell and a transducer chamber in which a differential pressure measuring sensor comprising a pressure-sensitive element is arranged. Differential pressure meters are used in particular for continuous measurement of the differential pressure in a measuring medium, for example in liquids, vapors, gases and dust. From the differential pressure, for example, the fill level height of a filling material in a storage tank or the flow rate of a measuring medium through a pipe conduit can be determined.

[0004] Silicon chips are generally used as pressure-sensitive elements. In order to achieve a good measurement sensitivity, the differential pressure transducer is preferably operated in the range close to the critical limit value of the pressure (nominal pressure). If the critical limit value is exceeded, there is a risk that the chip will be destroyed. Since silicon chips in particular have a relatively low overload resistance, differential pressure transducers are usually assigned an overload protection. This is preferably designed in such a way that it impairs the measurement sensitivity and the measurement accuracy of the pressure-sensitive element as little as possible.

[0005] WO 2018 / 165122 A1 discloses a differential pressure transducer of the coplanar type in which the pressure inlet with a separating diaphragm and an overload diaphragm is arranged in one plane, in particular in the end region facing the process. This is a so-called dual diaphragm system. The coplanar differential pressure transducer is constructed in such a way that it can be connected to a standardized 3051 interface. SUMMARY

[0006] It is an object of the present application to propose a differential pressure transducer which can be adapted to different customer connections.

[0007] It is an object of the application to be achieved by a coplanar differential pressure transducer, comprising a measuring cell and a transducer chamber, the measuring cell having two separate diaphragms facing the process, wherein two pressures are applied to the separate diaphragms, which pressures are hydraulically transmitted via corresponding capillary systems to pressure-sensitive measuring elements arranged in the transducer chamber. In the process-facing end region of the measuring cell, the measuring cell is designed as a process connection for a hardware interface of a customer connection. In the process-facing end face of the base body of the process connection, a disc-shaped recess is provided upstream of each of the two separate diaphragms. Each of the two disc-shaped recesses is in each case in the form of two circles with different radii, which intersect to form an elliptical structure. Two insert discs are provided, which have openings and correspond to the elliptical disc-shaped recesses. The insert discs can be mounted in the elliptical disc-shaped recesses and are designed such that the process connection can be adapted to the hardware interface of the customer connection.

[0008] According to a development, at least two different pairs of insert discs are provided, which are designed such that the process connection can be mounted on at least two different hardware interfaces, in particular on at least two different standard hardware interfaces, of a corresponding customer connection.

[0009] Furthermore, it is proposed that the elliptical disc-shaped recesses and the corresponding insert discs are dimensioned such that the circumferential weld seams are located outside the separate diaphragms for mounting the insert discs in the elliptical disc-shaped recesses. Preferably, the two elliptical disc-shaped recesses are arranged completely symmetrically to each other.

[0010] It is further proposed that the two elliptical disc-shaped recesses are arranged such that they adjoin each other with the two larger radii, while at the same time they are aligned with the two opposite outer edges of the process connection with the two smaller radii.

[0011] In the context of the application, it is provided that in the case of the two insert discs corresponding to a first hardware interface, the preferably circular openings are in each case located in the region of the larger radius. The first hardware interface is preferably a 3051 interface. Here, it is also provided that a circumferential annular groove is arranged around each of the two circular openings. This serves to receive a sealing. A second hardware interface can be, for example, an IEC interface. Here, it is provided that in the case of the two insert discs corresponding to a first hardware interface, the preferably circular openings are in each case located in the region of the smaller radius.

[0012] A further embodiment of the coplanar differential pressure transducer according to the application provides for the oval disk-shaped recesses to be sealed with corresponding blind insertion disks. By fastening the blind insertion disks in the oval recesses, these recesses are sealed in a pressure-tight and gas-tight manner. The pressure to be measured reaches the respective separating diaphragm, for example via a laterally extending hole at the process connection. BRIEF DESCRIPTION OF DRAWINGS

[0013] The application is explained in more detail with reference to the following drawings. In which:

[0014] Figure 1 A partial longitudinal section through the differential pressure transducer is shown, which shows the main components,

[0015] Figure 1 a A partial longitudinal section is shown Figure 1 An exploded view of the differential pressure transducer is shown,

[0016] Figure 2a A detail of a longitudinal section through the differential pressure transducer according to the application with a coplanar adapter is shown,

[0017] Figure 3a A plan view of the lower end face of the process adapter is shown,

[0018] Figure 3b A schematic overview of the position of the disk-shaped recess with an insertion disk for a customer interface (3051) is shown,

[0019] Figure 3c A partial schematic overview of the position of the disk-shaped recess with a left insertion disk for another customer interface (IEC) is shown,

[0020] Figure 3d A schematic overview of the position of the disk-shaped recess with an insertion disk for Figure 3c A plan view of the end face of the process adapter with an insertion disk for another customer interface is shown;

[0021] Figure 4 A schematic view of a coplanar differential pressure transducer with overload protection is shown, in which a coplanar adapter according to the application can be used. DETAILED DESCRIPTION

[0022] Figure 1 A perspective view of the differential pressure transducer 1 is shown, in which some of the components arranged inside can be seen through a partial longitudinal section. Figure 1 a is Figure 1 A partial exploded view of the differential pressure transducer 1 is shown.

[0023] The differential pressure transducer 1 comprises a pressure-tight or gas-tight unit formed by the process connection 21 and the housing adapter 22. The main components of the differential pressure transducer 1 are the measuring cell 2 integrated in the process connection 21 and the transducer chamber 3 in which the differential pressure measuring sensor 12 with the pressure-sensitive measuring element 13 is positioned.

[0024] In the process-facing region of the measuring cell 2, two separate diaphragms 5a, 5b are arranged adjacent, i.e. coplanar, in one plane. During the measuring operation of the differential pressure transducer 1, pressures pi, p2are applied to the diaphragms 5a, 5b, the difference dp of which is to be measured or determined. The pressures are supplied via the customer connection / valve block 24, which comprises customer interfaces 23a, 23b. Depending on the standard used, these customer interfaces 23a, 23b can vary in diameter and in the relative distance from one another. For example, the known standard is the 3051 standard, which is mainly used in the USA for connecting pressure sensors, or the IEC standard, which is used in many places in the world. In the 3051 standard, the customer interfaces 23a, 23b have a smaller relative distance from one another and a larger diameter compared to the case of the customer interfaces 23a, 23b in the IEC standard.

[0025] The two pressures pi, p2are hydraulically conducted from the diaphragms 5a, 5b via the corresponding capillary systems 10a, 10b, 11a, 11b to the two opposite pressure surfaces 13a, 13b of the pressure-sensitive measuring element 13. The capillary systems can be capillary bores in the base body 9, for example the base body 9 of the measuring cell 2 and the wall chamber 3, or also capillary bores in an intermediate body. Alternatively, in separate variants of the measuring cell and the transducer chamber, the capillary systems can also at least partially consist of capillary tubes. The measuring mechanism 2 is symmetrical, preferably completely symmetrical. This results in considerable advantages during manufacture.

[0026] In order to connect the pressure measuring transducer 1 and the customer connection 24 to one another via a bolt (not shown), in the process-facing end region of the measuring cell 2, the measuring cell 2 is designed as a process connection 21. By means of the coplanar adapter according to the application, which is arranged on or in the process-facing end region of the process connection 21, it is now possible to easily adapt or adapt the standard process connection 21 to different customer connections 24a, 24b.

[0027] The coplanar adapter for adapting the standard process adapter 21 to different customer interfaces 24a, 24b can be seen in different embodiments and illustrations in Figure 2a and Figure 3a to Figure 3d Figure 2a ​A longitudinal section through the process facing end region of the process connection 21 is shown. In the region of the process facing end face of the base body 9 of the process connection 21, a disc-shaped recess 17 is provided upstream of each of the two separation membranes 5a, 5b. Each of the two disc-shaped recesses is in each case in the form of two circles with different radii Ra, Rb, which intersect to form an elliptical structure. A corresponding insertion disc 19a or 19b with an opening 26a or 26b is inserted into the two elliptical disc-shaped recesses 17. The pressure pi, p2 reaches the separation membranes 5a, 5b via these openings 26a, 26b. The corresponding insertion disc 19a, 19b means that the form and size of the insertion disc 19a, 19b are adapted to the elliptical disc-shaped recess 17. This can be clearly seen by way of example in Figure 3a and Figure 3d The insertion disc 19a, 19b is designed in such a way that the process connection 21 can be adapted to the hardware interfaces 23a, 23b of the customer connection 24a, 24b.

[0028] For each customer connection 24a, 24b, there is a pair of matching insertion discs 19a, 19b via which the process connection 21 can be mounted on at least two different hardware interfaces 23a, 23b of the corresponding customer terminal 24a, 24b. Since the customer connections 24a, 24b are also largely standardized, it is sufficient to explicitly name two customer connections 24a, 24b: the 3051 standard and the IEC standard. These two standards have already been mentioned and described in more detail above.

[0029] The insertion discs 19a, 19b required for the customer connection 24a, 24b are mounted in the elliptical disc-shaped recess 17, so that the circumferential weld seam 25 for mounting the insertion disc 19a, 19b is located in the elliptical disc-shaped recess 17 outside the separation membrane 5a, 5b. This is important for ensuring that the functionality of the separation membrane 5a, 5b is not impaired by temperature effects during the welding process. The course of the weld seam is clearly visible in Figure 3d .

[0030] The two elliptical disc-shaped recesses 17 are arranged completely symmetrically with respect to one another, similar to the selected insertion disc 19a, 19b.

[0031] Figure 3bTwo oval disk-shaped recesses are shown which are arranged such that they adjoin each other with two larger radii Ra, while at the same time they are aligned with two opposite outer edges of the process connection 21 with two smaller radii Rb. The preferably circular openings 26a are in each case located in the region of the larger radii Ra. The dimensions of the recess 17 and in particular of the insert disk 19a are chosen such that the process connection 21 can be connected to a hardware interface 23a which is a 3051 interface. Each of the two circular openings 26a with the radius r1 is surrounded by a circumferential annular groove 20. This serves to receive a seal or sealing material.

[0032] Figure 3c A left-hand recess 17 and an insert disk 19b corresponding to a further hardware interface 23b are shown. The right-hand recess with the insert disk 19b is arranged coplanar therewith, but is not shown in Figure 3c Here, the preferably circular openings 26b are located in the region of the smaller radii Rb of the insert disk 19b. The circular openings have a radius r2. Preferably, the insert disk 19b is designed such that the process adapter 21 can be docked to a customer connection 24 according to an IEC standard.

[0033] Figure 4 A preferred embodiment of a particular differential pressure transducer 1 with overload protection is shown in which the coplanar adapters 17, 19a; 19b can be used. Of course, the adapters according to the application can be used with any embodiment of a coplanar differential pressure transducer 1; they are not limited to the embodiments described below. The differential pressure transducer 1 serves to determine the differential pressure between two pressures pi, p2. The measurement of the differential pressure between the two pressures pi, p2 serves, for example, to determine the flow in a pipe conduit. Another application of the differential pressure transducer 1 is, for example, to determine the filling level height of a fluid medium located in a storage tank.

[0034] The differential pressure transducer 1 comprises a measuring cell 2 and a transducer chamber 3. A coplanar dual diaphragm system with two dual diaphragms 4a, 4b is provided on or in an end region of the measuring cell 2 facing the process. The measuring cell 2 is arranged in a process connection 21. A differential pressure measuring sensor 12 with a pressure-sensitive element 13 is arranged in the transducer chamber 3. The transducer chamber 3 is located in a housing adapter 22. In the case shown, the transducer chamber 3 and the measuring cell 2 are offset from each other; the capillary conduits of the measuring cell 2 and the transducer chamber 3 are connected to each other via capillary conduits.

[0035] The two diaphragms 4a, 4b each comprise a process diaphragm 5a, 5b or separation diaphragm 5a, 5b and an overload diaphragm 6a, 6b, which is arranged behind the separation diaphragm 5a, 5b in the direction of action of the pressure. A first pressure chamber 7a is formed between the first separation diaphragm 5a and the first overload diaphragm 6a, and a first additional pressure chamber 8a or overpressure chamber 8a is formed between the first overload diaphragm 6a and the base body 9. Furthermore, a second pressure chamber 7b is formed between the second separation diaphragm 5b and the second overload diaphragm 6b, and a second additional pressure chamber 8b or second overpressure chamber 8b is formed between the second overload diaphragm 6b and the base body 9.

[0036] A first connecting capillary 10a is assigned to the first additional pressure chamber 8a, and a second connecting capillary 10b is assigned to the second additional pressure chamber 8b. A first auxiliary capillary 11a is assigned to the first pressure chamber 7a. A second auxiliary capillary 11b is assigned to the second pressure chamber 7b. In the embodiment shown, a pressure transfer coupling / intersection between the first auxiliary capillary 11a and the second connecting capillary 10b and between the second auxiliary capillary 11b and the first connecting capillary 10a is implemented in the measuring cell 2. Alternatively, as shown, it can take place in the transducer chamber 3. It is also possible that the intersection of the capillaries takes place behind the transducer chamber 3, or according to two alternative solutions: partly in the transducer chamber 3 and partly in the intermediate space, or partly in the transducer chamber 3 and partly in the measuring cell 2. Figure 1

[0037] In the embodiment shown, the pressure transfer and the limitation of the overpressure to an amount which does not damage or destroy the pressure-sensitive element 13 are operated in parallel, wherein the overpressure is limited in terms of pressure dynamics before it reaches the pressure measurement sensor 12. The limitation of the overpressure takes place via a respective predetermined preloading of the overload diaphragms 6a, 6b. These are preloaded in such a way that in normal measurement operation they bear against the housing of the base body 9 in a form-fitting manner and over approximately the entire surface, and only lift away from the base body 9 of the measuring cell 2 or of the process adapter 21 when a predetermined critical limit pressure is exceeded. Until this limit pressure, the integrity of the pressure-sensitive element is ensured.

[0038] During normal measurement operation, and in the event of an overpressure ​In the initial phase, the overload diaphragms 6a, 6b are in full surface contact with the base 9 of the measuring cell 2. This support is essentially form-fitting; thus, the overload diaphragms 6a, 6b are preloaded. The measuring pressures pi, p2are transmitted through the separating diaphragms 5a and 5b, the pressure chambers 7a and 7b, the connecting capillaries 10a and 10b and the auxiliary capillaries 11a and 11b to the rear side of the additional pressure chambers 8a, 8b and in parallel to the transducer chamber 3 or in parallel to the pressure-sensitive measuring element 13.

[0039] The overload diaphragms 6a, 6b and the measuring element 13 are hydraulically parallel, thus the same pressure acts on both. At the overload diaphragms 6a, 6b and the measuring element 13, the differential pressure dp is formed by pi - p2. The pressure-sensitive measuring element 13 deflects in accordance with the differential pressure. Since the overload diaphragms 6a, 6b are preloaded, it is necessary to prevent their deflection from reaching a defined value. The preloading is of course also greater than the measuring range.

[0040] The pressure-sensitive measuring element 13 receives the positive (+) pressure information via the pressure chamber 7b and the connecting capillaries 11b, 10a. The pressure information of the negative (-) side of the pressure-sensitive measuring element 13 is transmitted via the pressure chamber 7a and the connecting capillaries 11a, 10b. Due to the preloaded and approximately form-fitting support of the overload diaphragms 6a, 6b on the base 9 of the measuring cell 2, the influence via the parallel path of the additional pressure chambers 8a, 8b is virtually negligible.

[0041] In the case of an overload, i.e. when a one-sided overpressure occurs on the right side of the differential pressure transducer 1 The pressure on the separating diaphragm 5b and in the pressure chamber 7b increases. Since the overload diaphragm 6b is supported against the base 9, an increase in pressure in the additional pressure chamber 8b is not possible. The pressure is transmitted via the pressure chamber 7b to the connecting capillary 11b and via the connecting capillary 10a to the positive (+) side of the pressure-sensitive measuring element 13; in parallel, the pressure also acts on the rear side of the overload diaphragm 6a, which faces away from the process. If the pressure exceeds the preloading of the overload diaphragm 6a, the overload diaphragm 6a deflects and the additional pressure chamber 8a can receive the hydraulic fluid 16, typically silicone oil, which is expelled from the pressure chamber 7b. The pressure in the additional pressure chamber 8a and the downstream pressure chamber 7a continuously rises. The overload diaphragm 6a and the separating diaphragm 5a deflect in the direction of the process. This procedure ends only when all of the oil 16 is expelled from the pressure chamber 7b and the separating diaphragm 5b rests on the overload diaphragm 6b, which is supported on the base 9 of the measuring cell 2. Once this state is reached, the pressure inside the hydraulic system cannot increase further: the pressure limit, i.e. the overload protection, takes effect.

[0042] The capillary system of the differential pressure transducer 1 is filled with the transfer fluid 16 via these filling openings 15a, 15b. The filling openings 14a, 14b extend transversely in the process connection 21 or in the measuring cell 2. In the embodiment shown, the filling openings 14a, 14b extend parallel to the base surface of the process connection 21. The position is chosen such that the amount of oil required for filling is as low as possible.

[0043] For this purpose, the closure elements 15a, 15b are also arranged as close as possible to the intersection point of the capillaries 10a, 10b, 11a, 11b. Due to this arrangement in the interior of the differential pressure transducer 1, the filling openings 14a, 14b behind the closure elements 15a, 15b are protected from corrosion. In addition, the corresponding area of the filling openings 14a, 14b can also be potted against the outside, but this is not absolutely necessary due to the position of the filling openings 14a, 14b, which are closed from the outside.

[0044] The preferably spherical closure elements 15a, 15b, which are in each case provided as a pressure-tight, gas-tight or at least liquid-tight closure, are pressed into the filling openings 14a, 14b and subsequently plugged. In principle, other methods for closing the openings of the filling openings 14a, 14b are also usable. However, welding is viewed with caution in this respect, since a negative influence on the defined properties of the transfer fluid 16 can occur due to the temperature increase.

[0045] List of reference signs

[0046] 1 differential pressure transducer

[0047] 2 measuring cell

[0048] 3 transducer chamber

[0049] 4a, 4b first diaphragm, second diaphragm

[0050] 5a, 5b first separation diaphragm, second separation diaphragm

[0051] 6a, 6b first overload diaphragm, second overload diaphragm

[0052] 7a, 7b first pressure chamber, second pressure chamber

[0053] 8a, 8b first additional pressure chamber, second additional pressure chamber

[0054] 9 base body

[0055] 10a, 10b first connecting capillary, second connecting capillary

[0056] 11a, 11b first auxiliary capillary, second auxiliary capillary

[0057] 12 differential pressure measurement sensor

[0058] 13 pressure-sensitive differential pressure element

[0059] 14a, 14b filling opening

[0060] 15a, 15b closure element

[0061] 16 transfer fluid / hydraulic fluid / oil

[0062] 17 elliptical disc-shaped recess

[0063] 18 dynamic brake

[0064] 19 insertion plate

[0065] 20 circumferential groove

[0066] 21 process connection

[0067] 22 housing adapter

[0068] 23a, 23b hardware interface

[0069] 24a, 24b customer connection

[0070] 25 weld seam

[0071] 26a, 26b opening

Claims

1. A coplanar differential pressure transducer (1) having a measuring unit (2) and a transducer chamber (3), wherein the measuring unit (2) has two process-oriented separation diaphragms (5a, 5b), wherein two pressures (p1, p2) are applied to the separation diaphragms (5a, 5b), and the pressures are hydraulically transmitted via corresponding capillary systems (10a, 10b, 11a, 11b) to a pressure-sensitive measuring element (13) arranged in the transducer chamber (3), wherein, In the process-facing end region of the measuring unit (2), the measuring unit (2) is designed as a process connector (21) for a hardware interface (23a, 23b) of a customer connector (24a; 24b). A disc-shaped recess (17) is provided downstream of each of the two separating diaphragms (5a, 5b) in the process-facing end face of the base (9) of the process connector (21). Each of the two disc-shaped recesses presents a... The device consists of two circles of different radii (Ra; Rb) that intersect to form an elliptical structure, wherein two insert disks (19a; 19b) are provided corresponding to the elliptical disc-shaped recess (17). The insert disks have openings (26a; 26b) and can be installed in the elliptical disc-shaped recess (17). The insert disks are designed such that the process connector (21) can be adapted to the hardware interface (23a; 23b) of the customer connector (24a; 24b).

2. The coplanar differential pressure transducer according to claim 1, in, At least two pairs of different insert disks (19a, 19b) are provided, the insert disks (19a, 19b) being designed such that the process connector (21) can be mounted on at least two different hardware interfaces (23a, 23b) of the corresponding customer connector.

3. The coplanar differential pressure transducer according to claim 2, in, The insertion disks (19a, 19b) are designed to allow the process connector (21) to be mounted on at least two different standard hardware interfaces.

4. The coplanar differential pressure transducer according to claim 1 or 2, in, The elliptical disc-shaped recess (17) and the corresponding insertion disc (19a; 19b) are sized such that the circumferential weld (25) for mounting the insertion disc (19a; 19b) is located outside the separation diaphragm (5a, 5b) in the elliptical disc-shaped recess (17).

5. The coplanar differential pressure transducer according to claim 1 or 2, in, The two elliptical disc-shaped recesses (17) are arranged symmetrically about each other.

6. The coplanar differential pressure transducer according to claim 1 or 2, in, The two elliptical disc-shaped recesses are arranged such that the two elliptical disc-shaped recesses are adjacent to each other with two larger radii (Ra), while the two elliptical disc-shaped recesses are aligned with the two opposite outer edges of the process connector (21) with two smaller radii (Rb).

7. The coplanar differential pressure transducer according to claim 1 or 2, in, When the two insertion disks (19a) correspond to the first hardware interface (23a), the opening (26a) is located in the region of the larger radius (Ra) in each case.

8. The coplanar differential pressure transducer according to claim 7, in, The opening (26a) is circular.

9. The coplanar differential pressure transducer according to claim 7, in, The first hardware interface (23a) is a 3051 interface.

10. The coplanar differential pressure transducer according to claim 7, in, A circumferential annular groove (20) is arranged around each of the two circular openings (26a).

11. The coplanar differential pressure transducer according to claim 1 or 2, in, In cases where the two insertion disks (19b) correspond to the second hardware interface (23b), the opening (26b) is located in an area of ​​a smaller radius (Rb) in each case.

12. The coplanar differential pressure transducer according to claim 11, in, The opening (26b) is circular.

13. The coplanar differential pressure transducer according to claim 11, in, The second hardware interface (23b) is an IEC interface.

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