Pressure transducer for transmitting pressure of process medium

Abstract

The invention relates to a pressure transducer (1) for transmitting a pressure of a process medium, comprising: a metal body (2), a pressure sensor module (5), which comprises a ceramic insulating body (6) and a pressure sensor (7), an isolating membrane (8) to which the process medium can be applied from a first isolating membrane surface (8.1); wherein, in the ceramic insulating body (6), at least one electrically conductive contact pin (6.2) is inserted such that the contact pin (6.4) extends at least from a first end face (6.1) through the ceramic insulating body (6) to a second end face (6.2) opposite the first end face (6.1), and wherein the at least one contact pin (6.4) is further arranged and positioned in the ceramic insulating body (6), the distance (d) between the contact pin (6.4) and another electrically conductive component of the pressure transducer at the second end face is not less than a value specified in the standard DIN EN 60079-11 (2011 edition) for a gap in the air and / or a creepage distance.

Description

Technical Field

[0001] This invention relates to a pressure measuring transducer for transmitting the pressure of a process medium. Background Technology

[0002] Pressure transducers used for recording pressure are commonly used in industrial pressure measurement technologies for absolute pressure measurement, relative pressure measurement, and differential pressure measurement. Typically, the initial pressure of the medium acts on a diaphragm and is transmitted to the pressure sensor via a first hydraulic pressure transmission path. This hydraulic pressure transmission path is typically filled with a pressure-transmitting fluid to transmit the pressure to the pressure sensor. To allow the sensor signal to be extracted from the pressure-exposed area, a so-called glass-metal seal is usually used. The pressure sensor is placed on one side of this glass-metal seal, and the sensor signal is extracted from the pressure-exposed area via glass-encapsulated contact pins.

[0003] However, particularly in process industries and often in automation technologies, such pressure measuring transducers are typically used in areas with explosion hazards, i.e., so-called explosion-hazardous areas. For use in explosion-hazardous areas, minimum air distance and / or creepage distance is required between the intrinsically safe current circuit and the grounded metal part, for example, such as the metal platform of the pressure measuring transducer, which is grounded via a container to determine the pressure of the medium within that container.

[0004] When using the aforementioned glass-metal seal in a pressure measurement transducer designed for use in explosion-hazardous areas, the required air clearance and / or creepage distance can only be achieved with relatively considerable effort. For example, an additional non-conductive material may be placed between the glass-metal seal and the pressure sensor to provide the required air clearance and / or creepage distance.

[0005] The downside is that the additional non-conductive material must be manufactured separately and then installed in the pressure measuring transducer.

[0006] Therefore, one object of the present invention is to provide a pressure measuring transducer that is particularly suitable for use in explosion-hazardous areas and is easier to manufacture. Summary of the Invention

[0007] The objective of the present invention is achieved by the pressure measuring transducer as described in claim 1.

[0008] The pressure measuring transducer of the present invention for transmitting the pressure of a process medium includes: A metal base body having a surface and a receiving space for accommodating a pressure sensor module; The pressure sensor module includes a ceramic insulating body and a pressure sensor. The ceramic insulating body has a generally cylindrical or conical outer contour. The pressure sensor is positioned at a first end of the ceramic insulating body. The pressure sensor module is inserted into the metal base body such that the pressure sensor faces the insulating diaphragm and points towards the receiving space. The ceramic insulating body also engages with the metal base body on its lateral surfaces. The isolation diaphragm is fixed on the surface, wherein a pressure chamber is formed between the isolation diaphragm and the surface, the pressure chamber is connected to a hydraulic path via an opening in the surface, the isolation diaphragm is capable of contacting the process medium on a first isolation diaphragm surface, and the pressure chamber, the hydraulic path and the receiving space are filled with a pressure-transmitting liquid to transmit the pressure of the process medium to the pressure sensor; In the ceramic insulating body, at least one conductive contact pin is inserted such that the contact pin extends at least from the first end through the ceramic insulating body to a second end opposite to the first end, wherein the at least one contact pin is further arranged and positioned in the ceramic insulating body such that the distance between the contact pin and another conductive part of the pressure measuring transducer located at the second end is not less than the value specified in standard DIN EN 60079-11 (2011 edition) for air distance and / or creepage prevention distance.

[0009] An advantageous embodiment of the pressure measuring transducer of the present invention may specify that at least a portion of a reference pressure path is formed in the ceramic insulating body, through which a reference pressure can be supplied to the pressure sensor, and wherein the at least portion of the reference pressure path formed in the ceramic insulating body is implemented such that the path has a minimum length not less than the value specified in standard DIN EN 60079-11 (2011 edition) for air distance and / or creepage prevention distance.

[0010] Another advantageous embodiment of the pressure measuring transducer of the present invention may specify that the minimum length and / or distance is not less than the values ​​specified in Table 5 of standard DIN EN 60079-11 2022 for voltage of 30V and protection class ia, ib, for air distance and / or creepage prevention distance in air.

[0011] Another advantageous embodiment of the pressure measuring transducer of the present invention may specify that the minimum length and / or distance is not less than 1.5 mm, preferably not less than 1.75 mm, and particularly preferably not less than 2 mm.

[0012] Another advantageous embodiment of the pressure measuring transducer of the present invention may provide that another conductive component of the pressure measuring transducer includes the edge of the metal base body, wherein the ceramic insulating body is bonded to the metal base body by means of its lateral surface.

[0013] Another advantageous embodiment of the pressure measuring transducer of the present invention may provide that the ceramic insulating body includes a recess at the first end into which the pressure sensor is inserted, wherein the recess is preferably configured such that the pressure sensor is inserted into the recess to a maximum height, for example, half the actual height of the pressure sensor. Attached Figure Description

[0014] The invention will now be explained in more detail with reference to the accompanying drawings, which are shown below: Figure 1 Cross-sectional view of a pressure measuring transducer.

[0015] Figure 2 Cross-sectional view of an alternative pressure measurement transducer. Detailed Implementation

[0016] Figure 1 A cross-sectional view of a pressure measuring transducer 1 is shown. The pressure measuring transducer 1 includes a metal base body 2 (especially steel or stainless steel) having a surface 3, and a disc-shaped diaphragm 8 is fixed to this surface at its outer periphery by a surrounding weld, thereby forming a pressure chamber 9 between the base body 2 and the diaphragm 8. As shown, the diaphragm 8 may have multiple corrugations 8.3.

[0017] In the illustrated example of the embodiment, the base body 2 is formed of two parts. However, the invention is not limited to a two-part base body, but can also be applied to a one-part or more-than-two-part construction. The first part 2.1 of the base body has a disc-shaped form with a stepped recess 2.11 at the end facing the isolation diaphragm 8, and the first part is essentially a hollow cylindrical shape. The second part 2.2 of the base body is also disc-shaped and is implemented using its outer contour so that the second part can be inserted into the stepped recess 2.11. At the end away from the isolation diaphragm, the second part 2.2 of the base body has a recess 2.21 such that, in the installed state, when the second part is inserted into the first part of the base body, a receiving space 4 is formed in the base body 2 for receiving a pressure sensor, which will be described in more detail below. The first part 2.1 and the second part 2.2 of the base body are particularly press-fitted together with each other.

[0018] In the illustrated example of the embodiment, the orifice 10 extends from the pressure chamber 9 through the base body, and thus through a second portion of the base body, to form a hydraulic path for transmitting the first process pressure acting on the diaphragm to the pressure sensor module 5, which will be described in more detail below. To properly transmit the first process pressure, the pressure chamber, the orifice, and therefore the hydraulic path 10, are filled with a pressure-transmitting fluid. This pressure-transmitting fluid can be, for example, oil, particularly silicone oil.

[0019] The first portion of the base body 2.1 includes a preferred central hole 2.12 following the stepped recess 2.11, which extends through the base body to the rear end, i.e., the end away from the process. In this case, the central hole 2.12 refers to a hole extending along a rotation axis referencing the outer contour of the base body.

[0020] The pressure sensor module 5 is located in the central hole 2.12. According to the invention, the pressure sensor module 5 comprises a ceramic insulating body 6 (especially alumina and / or zirconium oxide) and a pressure sensor 7, which will be described in more detail below. The ceramic insulating body 6 has a generally cylindrical or conical outer profile with a diameter of several millimeters, for example, in the range of 5-15 mm, preferably in the range of 7.5-12.5 mm. Furthermore, the ceramic insulating body 6 may have a recess 6.5 at one end for receiving the pressure sensor 7. The recess 6.5 may be implemented such that the pressure sensor 7 can be inserted into the recess to a maximum height, for example, half the actual height of the pressure sensor 7. A plurality of metal contact pins 6.4 are inserted into the ceramic insulating body 6 to a portion of their length for electrical contact with the pressure sensor 7. The contact pins 6.4 are inserted such that at the end of the recess, i.e., at the end where the sensor pressure 7 is located, they terminate substantially flush with the ceramic insulating body 6 and extend outwards at a rear end of the ceramic insulating body 6 opposite to the end where the sensor pressure 7 is located. Alternatively, the metal contact pin may not terminate flush with the ceramic insulating body 6, but rather extend slightly beyond it. In this case, the contact pin 6.4 is pressure-fitted to the ceramic insulating body 6. This can be achieved, for example, by adhesive, welding, or by using a glass-metal seal to connect the contact pin 6.4 to the ceramic insulating body 6. Preferably, the contact pin 6.4 and the ceramic insulating body 6 can be implemented such that the contact pin 6.4 on the end face where the pressure sensor 7 is located has a particularly conical form 6.41. Figure 2 This allows the contact pin 6.4 to be supported on the ceramic insulating body 6 under pressure load.

[0021] Furthermore, the contact pin 6.4 is arranged and positioned within the ceramic insulating body 6 such that the distance d between the contact pin 6.4 and the edge of the metal base body 2 (i.e., the outer periphery of the hole in the base body, i.e., the junction of the ceramic insulating body 6 and the metal base body 2) is not less than the value specified in standard DIN EN 60079-11 (2011 edition) for air distance and / or creepage prevention distance. Specifically, this distance is not less than the value specified in Table 5 of standard DIN EN 60079-11 (2011 edition) for air distance and / or creepage prevention distance for a voltage of 30V and protection classes ia, ib. For example, the distance d can be selected to be not less than 1.5 mm, preferably not less than 1.75 mm, and particularly preferably not less than 2 mm. This air distance and creepage prevention distance are required to meet the isolation distance requirements of IEC 60079-11.

[0022] The electrical signal of the pressure sensor, which represents the pressure measurement value, can first be preprocessed by the electrical sensor circuit formed on the circuit board at the rear end, and then further regulated and prepared for communication via a common protocol (e.g., 4mA-20mA or digital fieldbus protocol).

[0023] Specifically, the ceramic insulating body 6 is pressure-tightly bonded to the base body 2 of the pressure measuring transducer 1 on its outer peripheral lateral surface. This can occur, for example, by welding, where metallization on the insulating body 6 is followed by hard soldering. Alternatively, the bonding can also occur via active brazing or diffusion welding. Alternatively, adhesives can also be used for bonding.

[0024] A reference pressure path 11 may additionally be formed in the ceramic insulating body 6 to guide the reference pressure to the pressure sensor 7, as will be described in more detail below. The reference path 11 may be formed by a channel placed in the insulating body 6, for example, by a pressing process or by means of a ceramic powder injection molding method (“ceramic injection molding”). In the illustrated example of the embodiment, the reference pressure path 11 includes an aperture extending parallel to the central axis of the ceramic insulating body 6; and a subsequent transverse aperture located on and connected to the aperture. When the pressure measuring transducer 1 is a reference pressure measuring transducer, atmospheric pressure is fed as the reference pressure via the reference path 11. When the pressure measuring transducer is an absolute pressure measuring transducer, the pressure sensor 7 is fed a defined pressure, particularly a vacuum, via the reference pressure path. In both cases, the reference pressure path 11 cannot be filled with a pressure-transmitting liquid.

[0025] In the case of this reference pressure measuring transducer, the reference path 11 formed in the ceramic insulating body 6 can continue in the metal base body and be guided to the outer surface of the base body. At this outer surface, a filter element 12 can also be positioned in front of the reference pressure path.

[0026] Advantageously, the reference pressure path 11 is formed such that the specifications regarding air distance and / or creepage prevention distance according to standard DIN EN 60079-11 (2011 edition) are achieved by a portion of the reference path 11, which is formed within the ceramic insulating body 6, and thus within the non-conductive insulating body 6. This means that the portion of the reference pressure path formed in the ceramic insulating body has a minimum length corresponding to the value for air distance and / or creepage prevention distance specified in standard DIN EN 60079-11 (2011 edition). In the example of the embodiment shown in the figures, this minimum length consists of two lengths L1 and L2 added together. In particular, the minimum length L1+L2 is not less than the value specified in Table 5 of standard DIN EN 60079-11 (2011 edition) for a voltage of 30V and protection classes ia, ib, for air distance and / or creepage prevention distance in air. For example, the portion of the reference pressure path 11 formed in the ceramic insulating body 6 can be implemented such that the minimum length L1+L2 is not less than 1.5 mm, preferably not less than 1.75 mm, and particularly preferably not less than 2 mm. The isolation distance of IEC 60079-11 is satisfied by the minimum length L1+L2 and the minimum distance, which is achieved by the minimum length from the conductive component (e.g., the metal base body).

[0027] When the pressure measuring transducer is configured as a differential pressure measuring transducer, the pressure sensor is fed a second process pressure via the reference pressure path. In this case, the reference pressure path 11 can also be filled with a pressure-transmitting liquid.

[0028] The pressure sensor 7 (e.g., a silicon chip) includes a measuring diaphragm 7.3 on which a first process pressure is supplied on a first side 7.1 (near the isolation diaphragm) and a reference pressure is supplied on a second side 7.2 (away from the isolation diaphragm). In this way, the measuring diaphragm 7.3 experiences a pressure-related deflection, which can be detected, for example capacitively or resistively, and converted into a corresponding electrical signal.

[0029] To keep the volume of the pressure-transmitting liquid in the receiving space 4 as small as possible, the pressure measuring transducer 1 further includes a filling element 13 disposed in the receiving space. The filling element 13 is implemented such that the hollow space between the wall of the receiving space 4 and the pressure sensor 7 is filled as completely as possible. The filling element 13 can be formed as a single piece or as multiple parts, especially two parts. Furthermore, the filling element 13 can be made of a non-conductive material, and is preferably made of a heat-resistant plastic that is chemically inert to the pressure-transmitting liquid.

[0030] List of reference numerals

[0031] 1. Pressure Measurement Transducer

[0032] 2. Metal base body

[0033] 2.1 The first part of the basic structure

[0034] 2.11 Stepped concave portion

[0035] 2.12 Center Hole

[0036] 2.2 The second part of the basic structure

[0037] 2.21 Recessed part

[0038] 3 Surface

[0039] 4. Receiving space

[0040] 4.1 Opening

[0041] 5. Pressure sensor module

[0042] 6. Ceramic insulation body

[0043] 6.1 First end of the insulating body

[0044] 6.2 The second end of the insulating body

[0045] 6.3 Lateral surfaces of the insulating body

[0046] 6.4 Conductive contact pins

[0047] 6.41 Deformation of the cone

[0048] 6.5 Recess

[0049] 7. Pressure sensor

[0050] 7.1 First surface of the pressure-sensitive device

[0051] 7.2 The second side of the pressure-sensitive device

[0052] 7.3 Measuring the diaphragm

[0053] 8. Separating membrane

[0054] 8.1 First separator sheet

[0055] 8.2 Second separator sheet

[0056] 8.3 Corrugations of the diaphragm

[0057] 9. Pressure chamber

[0058] 10. For example, hydraulic paths in the form of orifices.

[0059] 11 Reference Pressure Path

[0060] 12 Filter Elements

[0061] 13 Filling elements

[0062] d Distance

[0063] minimum length of L1+L2

Claims

1. A pressure measuring transducer (1) for transmitting the pressure of a process medium, comprising: A metal base body (2) having a surface (3) and a receiving space (4) for receiving a pressure sensor module (5); The pressure sensor module (5) includes a ceramic insulating body (6) and a pressure sensor (7). The ceramic insulating body (6) has a generally cylindrical or conical outer contour. The pressure sensor (7) is positioned at a first end (6.1) of the ceramic insulating body. The pressure sensor module (5) is inserted into the metal base body (2) such that the pressure sensor (7) faces the insulating diaphragm (8) and points towards the receiving space (4). The ceramic insulating body (6) is also engaged with the metal base body on a lateral surface (6.3). An isolation diaphragm (8) is fixed on the surface (2), wherein a pressure chamber (4) is formed between the isolation diaphragm and the surface, the pressure chamber (4) is connected to a hydraulic path (10) via an opening (4.1) in the surface, the isolation diaphragm (8) is capable of contacting the process medium on a first isolation diaphragm surface (8.1), and the pressure chamber (9), the hydraulic path (10) and the receiving space (4) are filled with a pressure-transmitting liquid to transmit the pressure of the process medium to the pressure sensor; In the ceramic insulating body (6), at least one conductive contact pin (6.2) is inserted such that the contact pin (6.4) extends at least from the first end (6.1) through the ceramic insulating body (6) to a second end (6.2) opposite to the first end (6.1), wherein the at least one contact pin (6.4) is further arranged and positioned in the ceramic insulating body (6) such that the distance (d) between the contact pin (6.4) and another conductive part of the pressure measuring transducer located at the second end is not less than the value specified in standard DIN EN 60079-11 (2011 edition) for air distance and / or creepage prevention distance.

2. The pressure measuring transducer according to claim 1, wherein, At least a portion of a reference pressure path (11) is formed in the ceramic insulating body (6), through which a reference pressure can be supplied to the pressure sensor (7), and wherein the at least portion of the reference pressure path (11) formed in the ceramic insulating body (6) is configured such that the path has a minimum length (L1+L2) not less than the value specified in standard DIN EN 60079-11 (2011 edition) for air distance and / or creepage prevention distance.

3. The pressure measuring transducer according to one or more of the preceding claims, wherein, The minimum length (L1+L2) and / or distance (d) shall not be less than the values ​​specified in Table 5 of standard DIN EN 60079-112022 for voltage of 30V and protection class ia, ib, for air distance and / or creepage prevention distance in air.

4. The pressure measuring transducer according to one or more of the preceding claims, wherein, The minimum length (L1+L2) and / or the distance (d) is not less than 1.5 mm, preferably not less than 1.75 mm, and particularly preferably not less than 2 mm.

5. The pressure measuring transducer according to one or more of the preceding claims, wherein, The other conductive component of the pressure measuring transducer (1) includes the edge of the metal base body (2), wherein the ceramic insulating body (6) is joined to the metal base body (2) by means of its lateral surface (6.3).

6. The pressure measuring transducer according to one or more of the preceding claims, wherein, The ceramic insulating body (6) includes a recess (6.5) at the first end (6.1), into which the pressure sensor (7) is inserted, wherein the recess (6.5) is preferably configured such that the pressure sensor (7) is inserted into the recess to, for example, half the actual height of the pressure sensor (7).

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