Pressure sensor for determining and / or monitoring a first pressure of a medium

Abstract

The invention relates to a pressure sensor (1) comprising: a measuring unit (3) having a cavity (4) which has a base surface (5) and a recess (6); a current feed-through (7) having a main body (8) with a front face (9), at least one connecting element (11) and a reference pressure path (12), wherein the current feed-through (7) is introduced into the cavity (4) in such a way that a space (13) is formed between the front face (9) and the base surface (5); a tube (14) which is arranged in the main body (8) and protrudes beyond the end face (9) in such a way that an end region (15) of the tube (14) engages the recess (6), wherein the recess (6) and the end region (15) are designed and arranged in such a way that a first through-hole (16) arranged in the measuring unit (3) is aligned with the reference pressure path (12).

Description

[0001] Pressure sensor for determining and / or monitoring the initial pressure of a medium

[0002] The invention relates to a pressure sensor for determining and / or monitoring a first pressure of a medium.

[0003] In pressure measurement technology, absolute pressure, differential pressure, and gauge pressure sensors are known. Absolute pressure sensors determine the prevailing pressure of a process medium absolutely, i.e., relative to a vacuum, while differential pressure sensors determine the difference between two different pressures of the process medium or media. With gauge pressure sensors, the pressure of the process medium to be measured is determined relative to a reference pressure, where the prevailing atmospheric pressure in the vicinity of the gauge serves as the reference pressure.

[0004] Pressure sensors have a pressure-sensitive measuring element, the so-called pressure sensor, on whose first and second surfaces pressure is applied. In the case of relative or absolute pressure sensors, the pressure of the process medium to be measured 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 sensors, a first and a second pressure of the process medium are applied to each surface. The measuring element bends depending on the relative pressure, which is formed by 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, among other things, between capacitive and piezoresistive pressure sensors.A large number of such pressure sensors are manufactured and distributed by companies of the Endress+Hauser Group.

[0005] The pressure sensor can consist of a silicon chip. Typically, the pressure sensor is located in a chamber filled with a pressure transmission medium and is electrically and mechanically connected via a cable gland. The initial pressure of the medium is measured across a diaphragm and transmitted from there, via the pressure transmission medium, to a first surface of the pressure sensor. A reference pressure, such as ambient air in the case of a relative pressure sensor, is provided on a second surface of the pressure sensor. This can be achieved using a reference air guide. For this purpose, a bore is provided in the measuring mechanism of the pressure sensor through which ambient air can enter the sensor. Additionally, a corresponding channel is located in the cable gland, which transfers the ambient air from the bore to the second surface of the pressure sensor. The bore and the channel must be aligned with each other.However, this alignment presents a challenge.

[0006] It is therefore an object of the present invention to provide a pressure sensor in which alignment of the reference air guide is made possible in a simple manner.

[0007] The problem is solved according to the invention by a pressure sensor according to claim 1.

[0008] According to the invention, the problem is solved by a pressure sensor for determining and / or monitoring a first pressure of a medium, with

[0009] - a measuring instrument with a recess, in particular a cylindrical one, which has a base surface and a recess,

[0010] - a current feedthrough with a base body having an end face, at least one connecting element and a reference pressure path, wherein the current feedthrough is inserted into the recess such that a space is formed between the end face and the bottom face,

[0011] - a tube which is arranged in the base body and extends beyond the front face at least in one end region, wherein the end region of the tube engages in the recess, wherein the recess and the end region of the tube are arranged and designed such that a first through-bore arranged in the measuring instrument is aligned with the reference pressure path,

[0012] - a pressure sensor arranged in the space, which can be subjected to the first pressure of the medium on a first surface and to a reference pressure on a second surface and is electrically connected to at least one connecting element,

[0013] - a separating membrane which can be subjected to the first pressure,

[0014] - a pressure transfer path designed to transfer the initial pressure from the separating membrane to the first surface.

[0015] The pressure sensor according to the invention facilitates the simple alignment of the reference pressure path and the first through-hole. In particular, it aligns the current passage and the measuring mechanism. The recess can be arranged in a cylindrical surface of the recess, for example. The tube can be designed as a hollow cylinder. The tube can be configured to allow the pressure sensor to be filled with the pressure transmission medium. For example, the tube can be a filling tube. After filling, the tube can be sealed. The end region of the tube and the recess can be configured to correspond with each other.

[0016] The base body can be made of stainless steel or an alloy containing at least nickel and / or chromium. The base body can be cylindrical. The at least one connecting element can be electrically insulated from the base body. The at least one connecting element serves for the electrical contact of the pressure sensor. Preferably, the feedthrough has two, three, or four connecting elements. The connecting elements can serve for supplying power to the pressure sensor and for data transmission between the pressure sensor and an evaluation unit of the pressure transducer. The at least one connecting element can project beyond the end face and / or the end face. The at least one connecting element and / or the base body can be metallic. The current passage can be an electrical feedthrough or a glass feedthrough.

[0017] The pressure sensor can be arranged such that the second surface can be subjected to a reference pressure via the reference pressure path. The separating membrane can be designed to transmit the first pressure to a pressure transmission medium. The pressure transmission path can be filled with a pressure transmission medium, particularly a hydraulic one, such as silicone or vegetable oil. The reference pressure path can be configured as a channel. In particular, the reference pressure path is configured as a rectangular channel.

[0018] In one embodiment, the recess and the tube are designed and arranged such that the orientation of the current passage in the measuring instrument is fixed. This prevents rotation of the current passage relative to the measuring instrument within the recess.

[0019] In one embodiment, the current passage has at least one second through-hole into which the at least one connecting element is inserted. The at least one connecting element can be arranged in at least one second through-hole extending between the end face and the end face and, in particular, can be electrically insulated from it.

[0020] In one embodiment, the at least one connecting element is inserted into the at least one second through-hole by means of a glass-metal seal. For example, the at least one connecting element can be inserted into the at least one second through-hole by means of a glazed insert. In another embodiment, the pressure sensor is electrically connected to the at least one connecting element by means of wire bonding.

[0021] In one embodiment, the current passage and the measuring instrument are connected by means of a circumferential weld. The weld runs transversely to the reference air duct formed by the first through-hole and the reference pressure line, so that the weld extends to both sides of the reference air duct.

[0022] In one embodiment, the weld is designed such that ambient air can pass from the first through-hole into the reference pressure path. The transition between the reference pressure path and the first through-hole can remain unobstructed by the weld or is not sealed by it. For details regarding the weld and the necessary welding process, reference is made to DE 10 2020 133 407 A1.

[0023] In one embodiment, the current passage has a receiving surface and the measuring device has a support surface corresponding to the receiving surface, wherein the current passage is received onto the support surface by means of the receiving surface.

[0024] In one embodiment, the recess is arranged in the contact surface.

[0025] In one embodiment, the tube is partially arranged within the base body. The tube can be arranged in a third through-bore located in the base body.

[0026] In one embodiment, the tube is inserted into the current passage, in particular the third through-hole, by means of a soldered joint. The soldered joint may consist of a hard solder.

[0027] The present invention will now be explained in more detail with reference to the following figures, Figs. 1-3. They show: Fig. 1: an embodiment of the pressure sensor according to the invention.

[0028] Fig. 2: one embodiment of the measuring device.

[0029] Fig. 3: one embodiment of the current passage.

[0030] Figure 1 shows an embodiment of a pressure sensor 1 according to the invention. The pressure sensor 1 is designed as a relative pressure sensor. The pressure sensor 1 comprises a measuring element 3 into which a recess 4 is provided, having a base surface 5 and a recess 6. The recess 4 can be cylindrical. The recess 6 can be arranged in a cylindrical surface of the recess 4. The recess 6 can, for example, be a groove, a depression, or a milled area.

[0031] The pressure sensor 1 further comprises a current feedthrough 7. The current feedthrough 7 includes a base body 8 with an end face 9, at least one connecting element 11, and a reference pressure path 12. The current feedthrough may also have an end face 10, which is arranged opposite the end face 9. The at least one connecting element 11 may be arranged at least partially between the end face 9 and the end face 10 and may optionally project beyond the end face 9 and / or the end face 10. The at least one connecting element 11 may be electrically insulated from the base body. The base body 8 may further have at least one second through-bore 20 into which the at least one connecting element 11 is inserted, for example, by means of a glass-metal seal. A tube 14 is also arranged in the base body 8.The tube 14 can be inserted into a third through-hole 25 arranged in the base body 8, for example by means of soldering. At least in one end region 15, the tube protrudes from the end face 9 of the current passage 7. The current passage 7 is shown by way of example in Fig. 3.

[0032] The current feedthrough 7 is inserted into the recess 4 such that a space 13 is formed between the end face 9 and the bottom surface 5. A pressure sensor 17 is arranged in the space 13, which can be subjected to the pressure p1 of the medium 2 on a first surface 17a and to a reference pressure p2 on a second surface 17b. The pressure sensor 17 is electrically connected to the at least one connecting element 11, for example by means of wire bonding. The pressure sensor 17 can be arranged on a spacer 26, which is inserted into the base body 8, in particular into an opening 27, and / or arranged on the end face 9. A predetermined distance between the pressure sensor 17 and the end face 9 can be maintained by means of the spacer 26. The pressure sensor 17 can be arranged relative to the current feedthrough 7 such that a reference pressure p2 is transmitted to the second surface 17b via the reference pressure path 12.The pressure sensor 1 further comprises a separating membrane 18 and a pressure transmission path 19. The pressure transmission path 19 can be filled with a pressure transmission medium and is designed to transmit the first pressure p1 from the separating membrane 18 to the first surface 17a of the pressure sensor 17.

[0033] The end section 15 of the tube 14 is designed to engage in the recess 6. The recess 6 and the end section 15 are arranged and designed such that a first through-hole 16 located in the measuring device 3 is aligned with the reference pressure path 12, in particular that the first through-hole 16 overlaps, and is in line with, the reference pressure path 12. The recess 6 and the end section 15 can be designed to correspond with each other. In particular, the recess 6 and the end section 15 can be designed and arranged such that the alignment of the current passage 7 in the measuring device 3 is fixed.

[0034] The current feedthrough 7 and the measuring instrument 3 can be connected by means of a circumferential weld 22. The weld 22 can be designed such that a transition between the first through-hole 16 and the reference pressure path 12 remains open, in particular, is not closed by the weld, while a border of the transition is welded. The current feedthrough 7 and the measuring instrument 3 can be welded together at a circumferential contact surface, with only the transition between the first through-hole 16 and the reference pressure path 12 remaining free of the weld.

[0035] The current feedthrough 7 can have a receiving surface 23 and the measuring instrument 3 a support surface 24, which is designed to correspond with the receiving surface 23. The current feedthrough 7 can be received on the support surface 24 by means of the receiving surface 23. The receiving surface 23 and / or the support surface 24 can be annular. In particular, the recess 6 can be provided in the support surface 24, as shown in more detail in Fig. 2.

[0036] Reference symbol list

[0037] 1 pressure sensor

[0038] 2 Medium

[0039] 3 Measuring instrument

[0040] 4 Exclusion

[0041] 5 floor area

[0042] 6 recess

[0043] 7 Current feedthrough

[0044] 8 basic shapes

[0045] 9 Front surface

[0046] 10 End surface

[0047] 11 Connecting element

[0048] 12 Reference pressure path

[0049] Room 13

[0050] 14 tubes

[0051] 15 End of the tube

[0052] 16 first through hole

[0053] 17 Pressure sensor

[0054] 17a first area

[0055] 17b second area

[0056] 18 Separating membrane

[0057] 19 Pressure transmission path

[0058] 20 second through hole

[0059] 22 Welding

[0060] 23 Recording area

[0061] 24 contact surfaces

[0062] 25 third through hole

[0063] 26 spacers

[0064] 27 Opening

Claims

Patent claims 1. Pressure sensor (1) for determining and / or monitoring a first pressure (p1) of a medium (2), with - a measuring instrument (3) with a recess (4) which has a base surface (5) and a notch (6), - a current feedthrough (7) with a base body (8) with an end face (9), at least one connecting element (11) and a reference pressure path (12), wherein the current feedthrough (7) is inserted into the recess (4) such that a space (13) is formed between the end face (9) and the bottom face (5), - a tube (14) which is arranged in the base body (8) and extends beyond the end face (9) at least in one end region (15), wherein the end region (15) engages in the recess (6), wherein the recess (6) and the end region (15) are arranged and designed such that a first through-hole (16) arranged in the measuring instrument (3) is aligned with the reference pressure path (12), - a pressure sensor (17) arranged in the space (13), which can be subjected to the first pressure (p1 ) of the medium (2) on a first surface (17a) and to a reference pressure (p2) on a second surface (17b) and is electrically connected to at least one connecting element (11 ), - a separating membrane (18) which can be subjected to the first pressure (p1 ), - a pressure transfer path (19) which is designed to transfer the first pressure (p1 ) from the separating membrane (18) to the first surface (17a).

2. Pressure sensor (1 ) according to claim 1, wherein the recess (6) and the tube (14) are designed and arranged such that the orientation of the current passage (7) in the measuring mechanism (3) is fixed.

3. Pressure sensor (1) according to one of the preceding claims, wherein the current passage (7) has at least one second through-hole (20) into which the at least one connecting element (11) is inserted.

4. Pressure sensor (1 ) according to claim 3, wherein the at least one connecting element (11 ) is inserted into the at least one second through-hole (20) by means of a glass-metal seal.

5. Pressure transducer (1 ) according to one of the preceding claims, wherein the pressure sensor (17) is electrically connected to the at least one connecting element (11 ) by means of wire bonding.

6. Pressure sensor (1) according to one of the preceding claims, wherein the current passage (7) and the measuring mechanism (3) are connected by means of a circumferential weld (22).

7. Pressure sensor (1 ) according to claim 6, wherein the weld (22) is designed such that ambient air can pass from the first through-hole (16) into the reference pressure path (12).

8. Pressure sensor (1) according to one of the preceding claims, wherein the current passage (7) has a receiving surface (23) and the measuring mechanism (3) has a support surface (24) corresponding to the receiving surface (23), wherein the current passage (7) is received onto the support surface (24) by means of the receiving surface (23).

9. Pressure sensor (1 ) according to claim 8, wherein the recess (6) is arranged in the support surface (24).

10. Pressure sensor (1 ) according to one of the preceding claims, wherein the tube (14) is partially arranged in the base body (8).

11. Pressure sensor (1) according to one of the preceding claims, wherein the tube (14) is inserted into the current passage (7) by means of a solder joint (25).

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