DE102016109645A1 - Pressure sensor element and capacitive pressure sensor - Google Patents

Abstract

Pressure sensor element (1) for a capacitive pressure sensor comprising: - at least one metallic tube (2); - At least one metallic contact pin (3); - A glass body (4) in which the tube and the contact pin (3) are melted on a part of their length such that they terminate at one end face of the pressure sensor element (1) substantially flush with the glass body (4) and on one of the end face protrude from the glass body (4) opposite rear side of the pressure sensor element (1); - A in the form of a pot, the glass body (4) surrounding metallic base body (5) in which the glass body (4) is melted, wherein the base body (5) on the front side of the pressure sensor element (1) is open and the base body (5) and the glass body (4) forming a substantially flush concave surface (6) on the front side, wherein the base body (5) at the back of the pressure sensor element (1) openings (7) for the tube and the contact pin (3), through which these are guided; - At least one on the end face on the glass body (4) at least partially applied metallic electrode (8) which is electrically contacted by the contact pin (3) from the back of the pressure sensor element (1).

Description

The invention relates to a pressure sensor element for a capacitive pressure sensor, a pressure sensor for determining a pressure and a pressure sensor for determining a differential pressure.

In the field of capacitive pressure measurement capacitive pressure sensors are well known. These usually comprise a measuring diaphragm and a counter body or basic body, wherein the measuring diaphragm is pressure-tightly connected to a base body along a peripheral edge, wherein between the base body and the measuring diaphragm a measuring chamber is formed, in which a reference pressure is applied, one of the Measuring chamber remote from the outside of the measuring membrane is acted upon with a pressure to be measured, so that the measuring diaphragm undergoes a pressure-dependent deformation, which is converted by means of a capacitive transducer into an electrical pressure measurement.

Such capacitive pressure sensors are used for detecting pressures and are often used in industrial measurement technology, for example for level measurement or flow measurement. Depending on the application, different types of pressure sensors are used. For example, a pressure sensor may be designed as an absolute pressure sensor, as a relative pressure sensor or as a differential pressure sensor.

In the case where the pressure sensor is designed as an absolute pressure sensor, one of the two sides of the measuring diaphragm is exposed to a vacuum and the other side of the measuring diaphragm is supplied with a measured media pressure. The absolute pressure sensor thus measures the absolute pressure, ie the medium pressure to be measured in comparison to the vacuum as a reference pressure.

In the case where the pressure sensor is designed as a relative pressure sensor, one of the two sides of the measuring diaphragm is exposed to an atmospheric air pressure as a reference pressure and the other side of the measuring diaphragm is supplied with a measured media pressure. The relative pressure sensor thus measures a relative pressure, ie the medium pressure to be measured in comparison to the atmospheric air pressure.

In the event that the pressure sensor is designed as a differential pressure sensor, one of the two sides of the measuring diaphragm is supplied with a first medium pressure to be measured and a second medium pressure to be measured is supplied to the other side of the measuring diaphragm. The differential pressure sensor thus measures a differential pressure, ie the difference between the two media pressures.

Such pressure sensors can only be realized by relatively expensive production processes.

It is therefore an object of the invention to provide a way by which the manufacturing cost of a pressure sensor can be lowered.

The object is achieved by a pressure sensor element for a capacitive pressure sensor, a pressure sensor for determining a pressure and a pressure sensor for determining a differential pressure.

• – mindestens ein metallisches Röhrchen;
• – mindestens einen metallischen Kontaktstift;
• – einen Glaskörper in den das Röhrchen und der Kontaktstift auf einem Teil ihrer Länge derartig eingeschmolzen sind, dass sie an einer Stirnseite des Drucksensorelements im Wesentlichen bündig mit dem Glaskörper abschließen und an einer der Stirnseite gegenüberliegenden Rückseite des Drucksensorelements aus dem Glaskörper herausragen;
• – einen in Form eines Topfes den Glaskörper umgebenden metallischen Grundkörper in dem der Glaskörper eingeschmolzen ist, wobei der Grundkörper an der Stirnseite des Drucksensorelements offen ist und der Grundkörper und der Glaskörper eine im Wesentlichen bündig konkave Oberfläche an der Stirnseite ausbilden, wobei der Grundkörper an der Rückseite des Drucksensorelementes Öffnungen für das Röhrchen und den Kontaktstift aufweist, durch welche diese geführt sind;
• – mindestens eine an der Stirnseite auf dem Glaskörper zumindest teilweise aufgebrachte metallische Elektrode, welche durch den Kontaktstift von der Rückseite des Drucksensorelements elektrisch kontaktierbar ist.

With regard to the pressure sensor element, the object is achieved by a pressure sensor element for a capacitive pressure sensor:

• - at least one metallic tube;
• - At least one metallic contact pin;
• - A glass body into which the tube and the contact pin are melted on a part of their length such that they terminate substantially flush with the glass body on an end face of the pressure sensor element and protrude from the glass body on a rear side of the pressure sensor element opposite the front side;
• A base metal body surrounding the glass body in the form of a pot in which the glass body is fused, the base body being open on the front side of the pressure sensor element and the base body and the glass body forming a substantially flush concave surface on the front side, wherein the base body adjoins the base body Rear side of the pressure sensor element has openings for the tube and the contact pin, through which they are guided;
• - At least one on the end face on the glass body at least partially applied metallic electrode which is electrically contacted by the contact pin from the back of the pressure sensor element.

According to the invention, a pressure sensor element is proposed, which can be produced inexpensively and nevertheless robustly by a glass-metal fusion process or a glass-metal implementation process and which subsequently serves to produce a pressure sensor.

An advantageous development of the invention provides that the metallic base body designed in the form of a pot has a substantially planar circular ring as the welding lip and on one of the front side remote lip back one, preferably substantially triangular, welding connection element is provided for welding the pressure sensor element.

A further advantageous embodiment of the invention provides that the metallic base body has an iron-nickel-cobalt alloy.

Yet another advantageous development of the invention provides that the metallic electrode is designed in the form of a ring electrode. In particular, the development provides that the metallic tube ends in an opening, preferably a central opening, of the annular electrode.

Again, a further advantageous embodiment of the invention provides that the concave surface is made by a spherical cut. Due to the fact that the concave surface is made by a spherical cut, this can be used as a membrane bed for a measuring membrane in an overload case, i. in overpressure, serve. Thus, in a pressure sensor, which is made of at least one such pressure sensor element, a defined overload resistance can be ensured.

With regard to the pressure sensor for determining a pressure, the object is achieved by a pressure sensor for determining a pressure, wherein the pressure sensor is a pressure sensor element according to a previously described embodiment and a substantially rotationally symmetrical a hollow cylindrical shape having, preferably metallic, housing body with a recess located on a base side and a flexible separation or measuring membrane, which is joined cohesively to the housing body in its edge region, wherein the pressure sensor element is inserted and fixed in the recess such that a pressure measuring chamber between the separation or measuring membrane and the concave surface on the The end face of the pressure sensor element is formed, wherein the pressure measuring chamber through the tube of the pressure sensor element, a reference pressure is fed, so that there is a pressure-dependent deflection of the separation or measuring membrane due to the reference pressure and one at the side facing away from the pressure sensor element side of the separation or measuring membrane applied media pressure results, wherein the pressure can be determined via a capacitance, which is formed from the electrode of the pressure sensor element and the separation or measuring membrane.

An advantageous development of the invention provides that the housing body is formed in two parts in the form of an inner and an outer sleeve, wherein the pressure sensor element is fixed to the inner sleeve and the inner sleeve is displaceable together with the pressure sensor element with respect to the outer sleeve.

A further advantageous development of the invention provides that the pressure measuring chamber is not filled with a pressure transfer fluid.

A further advantageous development of the invention provides that the recess is substantially stepped. In particular, the development provides that the pressure sensor element with the rear side of the pressure sensor element in the step-shaped recess to a weld lip, which frontally surrounds the base body, is introduced and the pressure sensor element is welded pressure-resistant manner to the housing body via the welding lip.

With respect to the pressure sensor for determining a differential pressure, the object is achieved by a pressure sensor for determining a differential pressure comprising a first and a second pressure sensor element, which are designed according to a previously described embodiment, and a measuring membrane, wherein the measuring diaphragm between the first pressure sensor element and the second pressure sensor element is arranged and is integrally connected in its edge region both with the first pressure sensor element and the second pressure sensor element, so that there is a first pressure measuring chamber between the diaphragm and the concave surface of the first pressure sensor element and a second pressure measuring chamber between the diaphragm and the concave surface of the second pressure sensor element forms, wherein the first pressure measuring chamber through the tube of the first pressure sensor element, a first pressure and the second pressure measuring chamber through the tube of the second pressure sensor element a second pressure is fed, so that there is a differential pressure-dependent deflection of the measuring membrane, wherein a first capacitor, which is formed from the electrode of the first pressure sensor element and the measuring membrane and / or a second capacitance, the from the electrode of the second pressure sensor element and the Measuring diaphragm is formed, the differential pressure between the first pressure and the second pressure can be determined.

An advantageous development of the invention provides that, furthermore, a first pressure-sensitive medium element with a first capillary line and a first hydraulic chamber, which is separated from a medium to be measured by at least one first separating membrane, and a second pressure-medium element with a second capillary line and a second hydraulic chamber, which is separated from a medium to be measured by at least one second separating membrane, wherein the first hydraulic chamber via the first capillary line hydraulically to the tube of the first Pressure sensor element, so as to form a first hydraulic chamber assembly and the second hydraulic chamber via the second capillary line hydraulically connected to the tube of the second pressure sensor element, so as to form a second hydraulic chamber composite, wherein the first and second chamber composite is filled with a pressure transmitting fluid, so in that a first media pressure of the first pressure measuring chamber and a second media pressure of the second pressure measuring chamber can be fed.

Yet another advantageous development of the invention provides that the concave surface of the first and the second pressure sensor element are designed such that they serve as a membrane bed for the measuring membrane. In the case of a pressure sensor for determining a differential pressure or differential pressure sensor, a defined one-sided overload resistance can be ensured on the basis of the two-sided concave surfaces.

The invention will be explained in more detail with reference to the following drawings. It shows:

1 FIG. 2: a cross section of a pressure sensor element according to the invention, FIG.

2a a rear view of the pressure sensor element according to the invention,

2 B FIG. 2: a plan view of the surface of the pressure sensor element according to the invention without an electrode, FIG.

2c : a top view of the surface of the pressure sensor element according to the invention with electrode,

3 a capacitive pressure sensor according to the invention, which works without a pressure transmission fluid, and

4 a capacitive differential pressure sensor according to the invention.

1 shows a cross section of a pressure sensor element according to the invention 1 , The pressure sensor element 1 includes a main body 5 , which is preferably in the form of a pot. The main body 5 consists of a metal, preferably a metal, which has a lower coefficient of thermal expansion than typical metals, typically a coefficient of thermal expansion in the range of 1-15 ppm / K, preferably in the range of 2-7 ppm / K, more preferably in about 5 ppm / K. Such a metal may, for example, represent an iron-nickel-cobalt alloy, which is also known under the trade name Kovar. For example, a typical iron-nickel-cobalt alloy may have a composition in mass percent of 25-33% nickel, 13-21% cobalt and balance iron, preferably a composition of 54% iron, 28% nickel and 18% cobalt.

The main body 5 has at one end face preferably a substantially annular welding lip 9 for welding the pressure sensor element 1 to another body, for example a housing body 12 a pressure sensor, on. Furthermore, a welding connection element 10 on a side facing away from the front side of the welding lip 9 be provided for the subsequent welding. The welding connection element 10 is preferably triangular. Furthermore, it may preferably be formed annularly without interruption.

With respect to the geometric dimensions of the formed in the form of a pot body 5 can have these dimensions of a transistor outline package. Such transistor outline packages represent standardized transistor housings, which can be produced more cost-effectively by the standardization, so that correspondingly produced pressure sensor elements can likewise be produced cost-effectively.

In the basic body 5 there is a glass body 4 , which uses a glass-metal fusion process together with a metallic tube 2 and a metallic contact pin 3 into the main body 5 is melted, so that a vacuum-tight connection between the glass and the metal is formed. The tube 2 and the contact pin 3 are doing so during the melting process in the vitreous body 4 they have been melted down so that they are essentially flush with the vitreous at the front 4 whereas at the rear, that is the side of the pressure sensor element opposite the front side, they terminate 1 to stand out. For the glass-metal fusion process, typically a preformed sintered glass part is used, into which the tube 2 and the contact pin 3 are introduced before the melting process. The main body 5 has corresponding openings on its rear side 7 on, through which the tube 2 and the contact pin 3 be led out. 2a shows a rear view of the pressure sensor element according to the invention 1 in which both for the tube 2 as well as for the contact pin 3 each one independent opening 7 is available.

The front side is the glass body 4 designed so that it has a concave surface 6 which, for example, can serve as a membrane bed for a measuring diaphragm in the event of an overload, if the pressure sensor element 1 is installed in a corresponding pressure sensor. The concave surface 6 can, for example. be made by a spherical cut. The spherical cut can be made, for example, with a thin cutting disc, which is rotated in addition to its direction of rotation. Alternatively, the pressure sensor element can be rotated. Regardless of how the spherical cut is made, the concave shape should 6 in any case, as accurately as possible to reproduce the shape of the measuring diaphragm in the overpressure case, because otherwise the measuring diaphragm would plastically deform in the overpressure case, which would lead to a lasting change in the pressure reading.

2 B shows a plan view of the surface of the pressure sensor element 1 , On the concave surface 6 then becomes an electrode 8th , For example, by means of a sputtering applied. 2c again shows a plan view of the surface of the pressure sensor element 1 in which such an electrode 8th is applied. The electrode 8th is preferably in the form of a ring electrode 11 formed, but may in principle also have other shapes. In the 2c illustrated ring electrode 11 is designed such that it has an opening 21 has, in which the metallic tube 2 empties. Preferably, the opening 21 centrally on or in the electrode 8th . 21 arranged. In addition to the in 2c illustrated embodiment, an embodiment with multiple electrodes is conceivable. Thus, for example, an inner and an outer ring electrode can be applied to the concave surface of the glass body. The electrode or electrodes can serve a capacitive pressure sensor according to the invention for the capacitive evaluation of a pressure measuring signal and / or determination of further information with regard to the pressure sensor, for example diagnostic information.

3 shows a capacitive pressure sensor according to the invention, which consists of a pressure sensor element 1 and a metallic housing body 12 consists. The in 3 illustrated housing body 12 is formed in one piece in such a way that it has a substantially hollow cylindrical shape and at one end a recess, preferably a step-shaped recess. The step-shaped recess serves as a stop for the welding lip 9 during insertion of the pressure sensor element 1 in the housing body 12 , That in the housing body 12 introduced pressure sensor element 1 is pressure-tight with the housing body 12 together. For example, a capacitor discharge welding can be used by means of which the pressure sensor element 1 on the housing body 12 is welded. Preferably, the welding connection element is used 10 to support the welding process.

Alternatively to the in 3 illustrated one-piece variant, the housing body 12 Also be formed in two parts, in which the housing body has an inner and an inner tightly enclosing outer metallic sleeve, which are vertically displaceable to each other. The inner and outer sleeves are designed so that the pressure sensor element 1 is fixable to the inner sleeve and the inner sleeve together with the pressure sensor element 1 vertical with respect to the outer sleeve is displaceable, so that the installation depth of the pressure sensor element 1 can be varied. For example, the inner sleeve and the outer sleeve can be adjustable relative to one another via a thread, which is formed on the contact surface between the inner and outer sleeve. In this variant, it can further be provided that the outer sleeve including the measuring diaphragm is made in one piece, so that no weld seam is present in the process.

Furthermore, the pressure sensor comprises a metallic flexible separation or measuring membrane 14 that the recess of the housing body 12 pressure tight closes, leaving a pressure measuring chamber 15 between the separation or measuring membrane 14 and the concave surface 6 with the electrode 8th arises. For this purpose, the separation or measuring membrane 14 in its edge region cohesively with the housing body 12 together. The separation or measuring membrane 14 has a dual function, so it serves on the one hand, the pressure measuring chamber 15 to separate from a medium, which at the pressure sensor element 1 opposite side of the separation or measuring membrane 14 on the other hand, it serves as an electrode 8th for a capacity by means of which a media pressure of the medium can be determined during measuring operation.

The pressure measuring chamber 15 is over the metallic tube 2 supplied to a reference pressure, which may be different depending on the configuration of the capacitive pressure sensor. In the case that the pressure sensor is designed as an absolute pressure sensor, the pressure measuring chamber is supplied with a vacuum as the reference pressure. In the case where the pressure sensor is configured as a relative pressure sensor, the pressure measuring chamber is supplied with an atmospheric air pressure as the reference pressure. In contrast to the known from the prior art relative or absolute pressure sensors, the pressure measuring chamber is not filled with a pressure-transmitting liquid. Thus, it is possible to build a metallic relative or absolute pressure sensor without hydraulic fluid.

Depending on the media pressure, which at the side facing away from the pressure sensor element side of the separation or measuring membrane 14 is applied and the reference pressure, experiences the separation or measuring membrane 14 a pressure-dependent deflection, so that the capacitance between the electrode 8th of the pressure sensor element 1 and the separation or measuring membrane 14 changes. This capacity change is made with the help of a not in 3 used evaluation unit for determining the pressure reading, so as to determine the pressure.

4 shows a further variant of a pressure sensor according to the invention, which is designed to determine a differential pressure. The differential pressure sensor comprises a first and a second pressure sensor elements 1a and 1b , which are constructed as described above. The pressure sensor elements 1a . 1b are arranged with their end faces to each other, with a metallic measuring diaphragm 16 between the first pressure sensor element 1a and the second pressure sensor element 1b is located, so that a first pressure measuring chamber 15a between the measuring membrane 16 and the concave surface of the first pressure sensor element 1a and a second pressure measuring chamber 15b between the measuring membrane 16 and the concave surface of the second pressure sensor element 1b results. The two pressure sensor elements 1a . 1b and the measuring membrane 16 are typically connected together in a weld.

The first pressure measuring chamber 15a is over the tube 2a the first pressure sensor element 1a a first pressure fed. This is on the tube 2a end a first capillary line 18a a first diaphragm seal element 17a fixed. The first capillary line 18a flows into a first hydraulic chamber 19a , which with a pressure-transmitting liquid, for example. A silicone oil, filled and by means of a first separation membrane 20a is separated from a first medium to be measured.

Analog is the second pressure measuring chamber 15b over the tube 2 B the second pressure sensor element 1b a second pressure fed. This is on the tube 2 B at the end a second capillary line 18b a second diaphragm seal element 17b fixed. The second capillary line 18b opens into a second hydraulic chamber 19b which is filled with a pressure-transmitting liquid, for example a silicone oil, and separated by means of a second separating membrane from a second medium to be measured.

Due to the filling of the first hydraulic chamber 19a and the second hydraulic chamber 19b as well as the first pressure measuring chamber 15a and second pressure measuring chamber 15b with the pressure-transmitting liquid is a on the first separation membrane 20a adjoining first media pressure of the first pressure measuring chamber 15a as the first pressure and on the second separation membrane 20b adjacent second medium pressure of the second pressure measuring chamber 15b supplied as a second pressure. This in turn leads to a differential pressure-dependent deflection of the measuring diaphragm 16 , by means of which a differential pressure between the first media pressure and the second media pressure can be determined.

To determine the differential pressure is at least a first capacity 8a . 16 which is from the electrode 8a of the first pressure sensor element 1a and the measuring membrane 16 is formed, used. Preferably, in addition, a second capacity 8b which is from the electrode 8b the second pressure sensor element 1b and the measuring membrane 16 is formed, used.

Such a constructed differential pressure sensor has the advantage that it is relatively simple and yet robust to produce. In addition, a cost-effective integration into a sensor assembly is possible. Such sensor modules typically include at least one mechanical interface to the process medium, also called process connection, and an electrical interface to the device electronics.

LIST OF REFERENCE NUMBERS

1

 Pressure sensor element

2

 tube

3

 pin

4

 vitreous

5

 body

6

 Concave surface

7

 Openings of the main body

8th

 electrode

9

 welding lip

10

 Welding connection element

11

 ring electrode

12

 housing body

13

 recess

14

 Separating or measuring membrane of the pressure sensor for determining a pressure

15

 Pressure measuring chamber of the pressure sensor for determining a pressure

16

 Measuring diaphragm of the differential pressure sensor

17

 Diaphragm seal element

18

 capillary

19

 Hydraulic chamber

20

 separating membrane

21

 Opening the electrode

Claims (14)

Pressure sensor element ( 1 ) for a capacitive pressure sensor comprising: - at least one metallic tube ( 2 ); At least one metallic contact pin ( 3 ); A vitreous body ( 4 ) into which the tube and the contact pin ( 3 ) are melted down on a part of their length in such a way that they are at an end face of the pressure sensor element ( 1 ) substantially flush with the vitreous body ( 4 ) and on one of the front side opposite back the pressure sensor element ( 1 ) from the vitreous ( 4 protrude; - one in the form of a pot the glass body ( 4 ) surrounding metallic body ( 5 ) in which the vitreous ( 4 ) is melted down, wherein the main body ( 5 ) on the front side of the pressure sensor element ( 1 ) is open and the main body ( 5 ) and the vitreous ( 4 ) has a substantially flush concave surface ( 6 ) form on the front side, wherein the main body ( 5 ) at the back of the pressure sensor element ( 1 ) Openings ( 7 ) for the tube and the contact pin ( 3 ), through which they are guided; At least one on the end face on the glass body ( 4 ) at least partially applied metallic electrode ( 8th ), which by the contact pin ( 3 ) from the back of the pressure sensor element ( 1 ) is electrically contactable. Pressure sensor element according to claim 1, wherein the formed in the form of a pot metallic base body ( 5 ) frontally a substantially planar circular ring as welding lip ( 9 ) and on one of the front side facing away lip back, preferably substantially triangular, welding connection elements ( 10 ) for welding the pressure sensor element ( 1 ) is provided. Pressure sensor element according to claim 1 or 2, wherein the metallic base body comprises an iron-nickel-cobalt alloy. Pressure sensor element according to at least one of the preceding claims, wherein the metallic electrode ( 8th ) in the form of a ring electrode ( 11 ) is trained. Pressure sensor element according to claim 4, wherein the metallic tube ( 2 ) end face in an opening, preferably the central opening, the ring electrode ( 11 ) opens. Pressure sensor element according to at least one of the preceding claims, wherein the concave surface is made by a spherical grinding. Pressure sensor for determining a pressure comprising a pressure sensor element according to claim 1 and a substantially rotationally symmetrical a hollow cylindrical shape having, preferably metallic, housing body ( 12 ) with a recess located on a base side ( 13 ) and a flexible separation or measuring membrane ( 14 ), which in its edge region cohesively with the housing body ( 12 ), wherein the pressure sensor element ( 1 ) in the recess ( 13 ) is inserted and fixed, that a pressure measuring chamber ( 15 ) between the separation or measuring membrane ( 14 ) and the concave surface ( 6 ) on the front side of the pressure sensor element ( 1 ), wherein the pressure measuring chamber ( 15 ) through the tube of the pressure sensor element ( 1 ) A reference pressure can be supplied, so that a pressure-dependent deflection of the separation or measuring membrane ( 14 ) due to the reference pressure and one at the pressure sensor element ( 1 ) facing away from the separation or measuring membrane ( 14 ) is applied, wherein over a capacity, which from the electrode ( 8th ) of the pressure sensor element ( 1 ) and the separation or measuring membrane ( 14 ) is formed, the pressure can be determined. Pressure sensor according to claim 7, wherein the housing body ( 12 ) is formed in two parts in the form of an inner and an outer sleeve, wherein the pressure sensor element ( 1 ) is fixed to the inner sleeve and the inner sleeve together with the pressure sensor element ( 1 ) is displaceable with respect to the outer sleeve. Pressure sensor according to one of claims 7 or 8, wherein the pressure measuring chamber ( 15 ) is not filled with a pressure transfer fluid. Pressure sensor according to one of claims 7 to 9, wherein the recess ( 13 ) is substantially stepped. Pressure sensor according to the preceding claim, wherein the pressure sensor element ( 1 ) with the back of the pressure sensor element in the stepped recess ( 13 ) to a welding lip ( 9 ), which end face the main body ( 5 ) is inserted, and the pressure sensor element ( 1 ) over the welding lip ( 9 ) on the housing body ( 12 ) is welded pressure-resistant. Pressure sensor for determining a differential pressure comprising a first and a second pressure sensor element according to claim 1 and a measuring diaphragm ( 16 ), which between the first pressure sensor element ( 1a ) and the second pressure sensor element ( 1b ) is arranged and in its edge region cohesively with both the first pressure sensor element ( 1a ) as well as the second pressure sensor element ( 1b ), so that a first pressure measuring chamber ( 15a ) between the measuring membrane ( 16 ) and the concave surface ( 6a ) of the first pressure sensor element ( 1a ) and a second pressure measuring chamber ( 15b ) between the measuring membrane ( 16 ) and the concave surface ( 6b ) of the second pressure sensor element ( 1b ), wherein the first pressure measuring chamber ( 15a ) through the tube ( 2a ) of the first pressure sensor element ( 1a ) a first pressure and the second pressure measuring chamber ( 15b ) through the tube ( 2 B ) of the second pressure sensor element ( 1b ), a second pressure can be supplied, so that a differential pressure-dependent deflection of the measuring diaphragm ( 16 ), with a first capacitance coming out of the electrode ( 8a ) of first pressure sensor element and the measuring diaphragm ( 16 ) is formed and / or via a second capacitor, which from the electrode ( 8b ) of the second pressure sensor element ( 1b ) and the measuring membrane ( 16 ) is formed, the differential pressure between the first pressure and the second pressure can be determined. Pressure sensor according to claim 12, further comprising a first diaphragm seal element ( 17a ) with a first capillary line ( 18a ) and a first hydraulic chamber ( 19a ), which by at least a first separation membrane ( 20a ) is separated from a medium to be measured, as well as a second diaphragm seal element ( 17b ) with a second capillary line ( 18b ) and a second hydraulic chamber ( 19b ), which by at least one second separation membrane ( 20b ) is separated from a medium to be measured, wherein the first hydraulic chamber ( 19a ) via the first capillary line ( 18a ) hydraulically to the tube ( 2a ) of the first pressure sensor element ( 1a ), so as to form a first hydraulic chamber assembly and the second hydraulic chamber ( 19b ) via the second capillary line ( 18b ) hydraulically to the tube of the second pressure sensor element ( 1b ), so as to form a second hydraulic chamber assembly, is connected, wherein the first and second chamber composite is filled with a pressure transfer fluid, so that a first media pressure of the first pressure measuring chamber ( 15a ) and a second medium pressure of the second pressure measuring chamber ( 15b ) can be fed. Pressure sensor according to claim 12 or 13, wherein the concave surface of the first and the second pressure sensor element are designed such that they are used as a membrane bed ( 25a . 25b ) for the measuring membrane ( 16 ) serve.

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