Temperature decoupler and system for monitoring and / or determining a first pressure of a medium

Abstract

The invention relates to a temperature decoupler (1) for a pressure sensor (2), with a basic body (3), wherein the base body (3) comprises a longitudinal axis (4), a first end region (5) and a second end region (6), wherein the first end region (5) is designed such that it (5) can be connected to the pressure sensor (2), wherein the second end region (6) is designed such that it (6) can be connected to a process connection (7), wherein the base body (3) between the first end region (5) and the second end region (6) is designed in the form of a single or multi-turn helix (8) which winds around the longitudinal axis (4), wherein the base body (3) has a bore (9) along the longitudinal axis (4) which can be filled with a pressure transmission medium. The invention further relates to a system (10) with such a temperature decoupler (1).

Description

[0001] The invention relates to a temperature decoupler for a pressure sensor, as well as a system for monitoring and / or determining a first pressure of a medium.

[0002] In pressure measurement technology, absolute pressure, differential pressure, and gauge pressure sensors are known. Absolute pressure sensors determine the prevailing pressure of a medium absolutely, i.e., relative to a vacuum, while differential pressure sensors determine the difference between two different pressures of the medium or media. With gauge pressure sensors, the pressure to be measured of the medium is determined relative to a reference pressure, with the atmospheric pressure prevailing in the vicinity of the gauge pressure sensor serving as the reference pressure.

[0003] Pressure transducers have a pressure-sensitive measuring element, the so-called pressure sensor, with a pressure applied to its first and second surfaces. In the case of relative or absolute pressure transducers, the pressure of the medium to be determined acts on the first surface of the pressure sensor, while an absolute or reference pressure acts on the second surface. In the case of differential pressure transducers, a first pressure and a second pressure of a medium are applied to both surfaces. The measuring element bends depending on the existing relative pressure, which is calculated from the difference between the pressures applied to the two surfaces. This bending is converted by an electronic unit into an electrical signal dependent on the relative pressure, which is then available for further processing or evaluation. A distinction is made between capacitive and piezoresistive pressure sensors, among others.A large number of such pressure sensors are manufactured and distributed by companies in the Endress+Hauser Group.

[0004] In the case of absolute and gauge pressure sensors, the pressure of the medium is measured by one, and in the case of differential pressure sensors, by two, pressure-sensitive separating diaphragms facing the process. Each separating diaphragm has an associated diaphragm bed, which typically serves to emboss the separating diaphragm and limit its movement in the event of an overload. Additionally, a pressure transmission medium is used, which transmits the pressure of the medium acting on the separating diaphragm via a pressure transmission path to one of the two surfaces of the pressure sensor.

[0005] Pressure transducers can have an additional separating diaphragm and are then known as a diaphragm seal. The additional second separating diaphragm is connected downstream of the (first) separating diaphragm, so that the pressure of the medium is initially absorbed by the (first) separating diaphragm and then transferred to the additional second separating diaphragm. The pressure of the medium is then applied to the pressure sensor via the second separating diaphragm. By using two separating diaphragms connected in series, any penetration of medium into the area of ​​the pressure sensor is largely prevented. Diaphragm seals are generally designed so that if the (first) separating diaphragm leaks, only the latter needs to be replaced, while the second separating diaphragm and the pressure sensor are retained.

[0006] In both pressure transducers and diaphragm seals, the pressure sensor is usually mounted at a distance from the medium due to its temperature sensitivity. At high process temperatures, temperature isolators are often used to protect the pressure sensor from high temperatures. Such temperature isolators are typically manufactured as long, rotationally symmetrical turned parts located between the isolating diaphragm and the pressure sensor. Since the temperature isolators are sometimes exposed to forces such as vibrations, the temperature isolator must have sufficient flexural strength. This is usually ensured by a correspondingly large cross-section of the temperature isolator.However, since the cross-section is crucial for the heat flow through the temperature isolator, these types of temperature isolators are long enough to achieve the desired temperature decoupling, resulting in significant space requirements, material requirements, and costs. The long length of the temperature isolators also makes it difficult to create a bore or capillary for a pressure transfer medium along the longitudinal axis of the temperature isolator.

[0007] The object of the present invention is therefore to provide a temperature decoupler which can be manufactured in a simple manner.

[0008] According to the invention, the object is achieved by a temperature decoupler according to claim 1 and a system for monitoring and / or determining a first pressure of a medium according to claim 8 as well as a system for monitoring and / or determining a first pressure of a medium according to claim 10.

[0009] With regard to the temperature decoupler, the task is solved by a temperature decoupler for a pressure sensor, with a base body, wherein the base body comprises a longitudinal axis, a first end region and a second end region, wherein the first end region is designed such that it can be connected to the pressure sensor, wherein the second end region is designed as a process connection with a first separating membrane which can be subjected to the first pressure, or for connection to a process connection, wherein the base body between the first end region and the second end region is designed in the form of a single or multi-threaded helix which winds around the longitudinal axis, wherein the base body has a bore along the longitudinal axis which can be filled with a pressure transmission medium.

[0010] By designing the base body as a helix, a large surface area is achieved, which results in high convection to the ambient air. This improved shape of the base body allows the temperature decoupler according to the invention to be manufactured significantly shorter than conventional temperature decouplers while maintaining the same heat exchange. The shorter length of the temperature decoupler according to the invention significantly simplifies the production of the bore, which is difficult to manufacture, especially with long base bodies. Furthermore, the helix gives the temperature decoupler according to the invention a high degree of robustness, enabling it to withstand the conditions prevailing in the process plant, such as high temperatures and vibrations.

[0011] The temperature decoupler, or at least the helix itself, can be manufactured using investment casting or 3D printing, for example. The helix can be left- or right-handed. A helix is ​​defined as a helical structure that winds around its longitudinal axis. A multi-threaded helix is ​​obtained by placing an additional helix offset by a defined pitch or a defined turn from a first helix or the other helixes.

[0012] In a further development, the helix is ​​designed with two or three threads. By designing the helix with two or three threads, a particularly large surface area can be created with high heat exchange within the helix.

[0013] In one embodiment, the helix has a predetermined pitch.

[0014] Preferably, the slope has an angle of 40° to 75°, in particular of 40° to 50°, in particular of 45°.

[0015] In a further embodiment, the diameter of the base body decreases from the second end area to the first end area. This reduces heat conduction toward the pressure sensor. It also ensures that the temperature isolator is designed to be as stable as possible toward the process connection.

[0016] A further embodiment provides that the diameter of the helix decreases continuously from the second end region to the first end region.

[0017] In particular, the diameter of the helix decreases monotonically from the second end region to the first end region.

[0018] Advantageously, the thickness of the helix is ​​smaller in the region of the longitudinal axis than in a region located further radially outward. This design of the helix increases its robustness and ensures that heat is effectively dissipated to the outside air. The thickness of the helix can be greatest, particularly in an edge region of the helix opposite the longitudinal axis. In particular, the helix can have the shape of a rotor blade or cloverleaf in cross-section.

[0019] Furthermore, the object underlying the present application is achieved by a system for monitoring and / or determining a first pressure of a medium with - a pressure transducer with a first connection area and a pressure sensor, which can be subjected to the first pressure on a first surface and to a second pressure on a second surface, - a process connection with a second connection area and a first separating membrane which can be subjected to the first pressure, - a temperature decoupler according to one of the preceding embodiments, wherein the first end region is connected to the first connection region, wherein the second end region is connected to the second connection region, and - a pressure transmission path configured to transmit the first pressure from the first separation membrane through the bore to the first surface of the pressure sensor.

[0020] The system according to the invention comprises the temperature decoupler according to the invention, which, due to its partially helical base body, offers improved heat exchange with the environment, so that the temperature decoupler can be designed shorter than conventional temperature decouplers. The pressure transmission path is preferably filled with a pressure transmission medium. The second end region in this system according to the invention is designed such that it can be connected to the process connection.

[0021] In a further development, the pressure sensor has a second separating membrane arranged along the pressure transmission path, so that a first section of the pressure transmission path transmits the first pressure from the first separating membrane through the bore to the second separating membrane, and a second section of the pressure transmission path transmits the first pressure from the second separating membrane to the first surface of the pressure sensor. The second separating membrane can prevent medium from penetrating the pressure sensor in the event of a leak in the first separating membrane.

[0022] With regard to the system, the object is further achieved by a system for monitoring and / or determining a first pressure of a medium with - a pressure transducer with a first connection area and a pressure sensor, which can be subjected to the first pressure on a first surface and to a second pressure on a second surface, - a temperature decoupler according to one of the preceding embodiments, wherein the first end region is connected to the first connection region, wherein the second end region is designed as a process connection with the first separation membrane, and - a pressure transmission path configured to transmit the first pressure from the first separation membrane through the bore to the first surface of the pressure sensor.

[0023] In the second system according to the invention, the second end region is a process connection with a first separation membrane. The process connection is thus integrated into the temperature isolator.

[0024] In a further development, the pressure sensor has a second separating membrane which is arranged along the pressure transmission path, so that a first section of the pressure transmission path transmits the first pressure from the first separating membrane through the bore to the second separating membrane and a second section of the pressure transmission path transmits the first pressure from the second separating membrane to the first surface of the pressure sensor.

[0025] In the following, the invention will be explained with reference to the following figures Fig. 1-7 are explained in more detail. They show: Fig. 1a: a temperature decoupler according to the invention in front view and in longitudinal section. Fig. 1b: a cross-section of a temperature decoupler according to the invention. Fig. 2: a second embodiment of the temperature decoupler according to the invention. Fig. 3: a third embodiment of the temperature decoupler according to the invention. Fig. 4: a first embodiment of a system according to the invention. Fig. 5: a second embodiment of a system according to the invention. Fig. 6: a third embodiment of a system according to the invention. Fig. 7: a fourth embodiment of a system according to the invention.

[0026] The Fig. The temperature decoupler 1 according to the invention shown in Figure 1a comprises a base body 3 with a longitudinal axis 4. The base body 3 further comprises a first end region 4, which is designed for connection to a pressure sensor 2, and a second end region 5, which is designed for connection to a process connection 7. Furthermore, the base body 3 has a bore 9 along the longitudinal axis 4, which can be filled with a pressure transmission medium, for example, a silicone oil.

[0027] Between the first end region 4 and the second end region 5, the base body 3 is designed in the form of a single or multi-threaded helix 8, which winds around the longitudinal axis 4. In the Fig. The configuration shown in Figure 1a is a three-threaded helix 8, the three threads of which are each arranged offset by 120°. The arrangement of the three threads is shown in Fig. 1b, which shows the temperature decoupler 1 in cross-section. However, the helix 8 can also be designed with a single or double thread or have more than three threads. The helix 8 is designed, for example, in the form of a rotor blade. In this case, the thickness of the helix 8 in the region of the longitudinal axis 4 is smaller than in a radially further outward region 19. The helix 8 can have a predetermined pitch, which in particular has an angle of 40° to 75°, in particular of 40° to 50°, in particular of 45°. By way of example, in Fig. 1a shows a pitch of the three-threaded helix 8 with a pitch of 45°. The diameter of the base body 3 can decrease from the second end region 6 toward the first end region 5, in particular continuously and / or monotonically.

[0028] In Fig. 2 shows a second embodiment of the temperature decoupler 1 according to the invention, which has a particularly short length.

[0029] In Fig. 3 shows a third embodiment of the temperature isolator 1 according to the invention. In this embodiment, the second end region 6 is designed as a process connection 7, which comprises a first separating membrane 16. The first separating membrane 16 can be subjected to the first pressure p1 of the medium 20. The process connection 7 has, for example, a connection region for connection to a container. Optionally, the base body 3 can have a filling bore 21, which serves to fill the bore 9 with a pressure transmission medium. The filling bore 21 is also provided with the Fig. 1 and Fig. 2 shown variant of the temperature decoupler 1.

[0030] Fig. 4 shows a first embodiment of a system 10 according to the invention. The system 10 serves to monitor and / or determine a first pressure p1 of a medium 20 and comprises a pressure sensor 2, a process connection 7 and a temperature isolator 1. The process connection 7 has a second connection region 15 for connection to the temperature isolator 1 and a first separating membrane 16, which can be subjected to the first pressure p1. The second connection region 15 is connected to the second end region 6 of the temperature isolator 1. The first end region 5 of the temperature isolator 1 is connected to a first connection region 11 of the pressure sensor 2. The connections between the first connection region 11 and the first end region 5 and between the second connection region 15 and the second end region 6 can be produced, for example, by welding or joining.

[0031] In addition to the first connection area 11, the pressure sensor 2 has a pressure sensor 12, which can be subjected to the first pressure p1 on a first surface 13 and to a second pressure p2 on a second surface 14 opposite the first surface. The second pressure p2 can be, for example, a second pressure of the medium 20, an ambient pressure, or an absolute pressure, e.g., a vacuum. The pressure sensor 2 can be configured as a differential, relative, or absolute pressure sensor.

[0032] The system 10 further comprises a pressure transmission path 17, which is designed to transmit the first pressure p1 from the first separating membrane 16 through the bore 9 to the first surface 13 of the pressure sensor 12. The pressure transmission path 17 can be filled with a pressure transmission medium, in particular a hydraulic one.

[0033] The Fig. The second embodiment of the system according to the invention shown in Figure 5 has, compared to the Fig. 2, the pressure sensor 2 additionally has a second separating membrane 18. This second separating membrane 18 is arranged along the pressure transmission path 17, so that a first section 17a of the pressure transmission path 17 transmits the first pressure p1 from the first separating membrane 16 through the bore 9 to the second separating membrane 18, and a second section 17b of the pressure transmission path 17 transmits the first pressure p1 from the second separating membrane 18 to the first surface 13 of the pressure sensor 12. In the event of damage to the first separating membrane 16, the second separating membrane 18 prevents contamination of the pressure sensor 12.

[0034] The two figures Fig. 6 and Fig. 7 each show an embodiment of the system according to the invention, in which the second end region 6 of the temperature decoupler 1 is designed as a process connection 7, which has the first separation membrane 16. The further features are analogous to those of the figures Fig. 4 and Fig. 5, which have already been described. List of reference symbols 1 temperature decoupler 2 pressure sensors 3 basic bodies 4 Longitudinal axis 5 first end area 6 second end area 7 Process connection 8 Helix 9 Hole 10 systems 11 first connection area 12 Pressure sensor 13 first area 14 second area 15 second connection area 16 first separation membrane 17 Pressure transmission path 17a first section 17b second section 18 second separation membrane 19 Area 20 Medium 21 Filling hole

Claims

[1] Temperature decoupler (1) for a pressure sensor (2), with a base body (3), wherein the base body (3) comprises a longitudinal axis (4), a first end region (5) and a second end region (6), wherein the first end region (5) is designed such that it (5) can be connected to the pressure sensor (2), wherein the second end region (6) is designed as a process connection (7) with a first separating membrane (16) which can be subjected to the first pressure (p1), or for connection to a process connection (7), wherein the base body (3) between the first end region (5) and the second end region (6) is designed in the form of a single- or multi-threaded helix (8) which winds around the longitudinal axis (4), wherein the base body (3) has a bore (9) along the longitudinal axis (4) which can be filled with a pressure transmission medium. [2] Temperature decoupler (1) according to claim 1, wherein the helix (8) is two- or three-threaded. [3] Temperature decoupler (1) according to one of claims 1-2, wherein the helix (8) has a predetermined pitch. [4] Temperature decoupler (1) according to claim 3, wherein the slope has an angle of 40° to 75°, in particular of 40° to 50°, in particular of 45°. [5] Temperature decoupler (1) according to one of claims 1-4, wherein the diameter of the base body (3) decreases from the second end region (6) towards the first end region (5). [6] Temperature decoupler (1) according to one of claims 1-5, wherein the diameter of the helix (8) decreases continuously from the second end region (6) towards the first end region (5). [7] Temperature decoupler (1) according to one of claims 1-6, wherein a thickness of the helix (8) in the region of the longitudinal axis (4) is smaller than in a radially further outward region (19). [8] System (10) for monitoring and / or determining a first pressure (p1) of a medium (20) with - a pressure transducer (2) with a first connection area (11) and a pressure sensor (12) which can be subjected to the first pressure (p1) on a first surface (13) and to a second pressure (p2) on a second surface (14), - a process connection (7) with a second connection area (15) and a first separating membrane (16) which can be subjected to the first pressure (p1), - a temperature decoupler (1) according to one of claims 1-7, wherein the first end region (5) is connected to the first connection region (11), wherein the second end region (6) is connected to the second connection region (15), and - a pressure transmission path (17) which is designed to transmit the first pressure (p1) from the first separating membrane (16) through the bore (9) to the first surface (13) of the pressure sensor (12). [9] System (10) according to claim 8, wherein the pressure transducer (2) has a second separating membrane (18) arranged along the pressure transmission path (17) such that a first section (17a) of the pressure transmission path (17) transmits the first pressure (p1) from the first separating membrane (16) through the bore (9) to the second separating membrane (18) and a second section (17b) of the pressure transmission path (17) transmits the first pressure (p1) from the second separating membrane (18) to the first surface (13) of the pressure sensor (12). [10] System (10) for monitoring and / or determining a first pressure (p1) of a medium (20) with - a pressure transducer (2) with a first connection area (11) and a pressure sensor (12) which can be subjected to the first pressure (p1) on a first surface (13) and to a second pressure (p2) on a second surface (14), - a temperature decoupler (1) according to one of claims 1-7, wherein the first end region (5) is connected to the first connection region (11), wherein the second end region (6) is designed as a process connection (7) with the first separation membrane (16), and - a pressure transmission path (17) which is designed to transmit the first pressure (p1) from the first separating membrane (16) through the bore (9) to the first surface (13) of the pressure sensor (12). [11] System (10) according to claim 10, wherein the pressure transducer (2) has a second separating membrane (18) arranged along the pressure transmission path (17) such that a first section (17a) of the pressure transmission path (17) transmits the first pressure (p1) from the first separating membrane (16) through the bore (9) to the second separating membrane (18) and a second section (17b) of the pressure transmission path (17) transmits the first pressure (p1) from the second separating membrane (18) to the first surface (13) of the pressure sensor (12).

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