DE102016107236A1 - Method for joining a differential pressure measuring cell and differential pressure measuring cell - Google Patents

Abstract

The invention relates to a method for joining a differential pressure measuring cell (1) and a differential pressure measuring cell (1) produced by the method. In the method joining material (FM) on the measuring membrane (2) facing end face (13a) of the first support body (51) or on the measuring membrane (2) facing away from the end face (12a) of the first counter body (41) and on the measuring membrane (2) facing the end face of the second support body (13b) or on the measuring membrane (2) facing away from the end face (12b) of the second counter body (42) applied. On at least one of the end faces (12a; 12b; 13a; 13b), the joining material (FM) is applied in a structured manner during application so that the end face (12a; 12b; 13a; 13b) has a continuous, inner region (31) without joining material (FM ), and in that the end face (12a; 12b; 13a; 13b) has a continuous outer region (32) with joining material (FM) substantially surrounding the inner region (31). In the pressure-tight connection of counter-body (41, 42) and support body (51, 52), a hydraulic chamber (8) between counter-body (41; 42) and support body is formed by the inner region (31) without joining material (FM) in at least one of the connecting planes (51, 52) formed.

Description

The invention relates to a method for joining a differential pressure measuring cell and a differential pressure measuring cell produced by the method.

Differential pressure measuring cells have to measure the difference between two static pressures p1 and p2 on a measuring diaphragm, which is arranged to form two hermetically separated measuring chambers between two counter-bodies. The measuring chambers are each acted upon by the pressures p1 and p2 via pressure channels introduced into the counter-bodies. A deflection of the measuring diaphragm is thus a measure of the pressure difference | p1 - p2 |, whereby the deflection of the diaphragm is converted by means of a transducer into an electronic measuring signal. For example, forms in capacitive differential pressure measuring cells, the measuring diaphragm together with a measuring membrane facing and parallel to the measuring membrane and conductive plane of the counter body a capacitor. Thus, the deflection of the measuring diaphragm determines the distance between the condenser, so that the differential pressure acting on the measuring diaphragm can be converted into a measuring signal by means of capacitance measurements. Such a pressure difference measuring cell is for example in the patent DE 103 94 943 B3 described. Pressure difference measuring cells, which are used in the process and / or automation technology of industrial plants for monitoring process pressures, are manufactured and distributed by the E + H Group in a wide variety of designs.

Because differential pressure cells are designed to have low pressure differences | p1 - p2 | When measuring simultaneously high static pressures p1, p2, the right balance between sensitivity and overload resistance is of central importance. For example, for the measuring range of the pressure difference | p1 - p2 | the following relationship applies: | p1 - p2 | / p1 <1%. Not applicable in a process plant of either pressure (e.g., p2), | p1 - p2 | / p1 reaches nearly 100%. In this case, the differential pressure measuring cell is thus loaded with more than 100 times the measuring range, which corresponds to a very high unilateral pressure load. For differential pressure cells with a very fine measuring range of | p1 - p2 | ~ 10 mbar is the one-sided pressure load in relation to the measuring range correspondingly higher at a typical process pressure of 160 bar.

The prior art discloses various embodiments for overload protection of differential pressure measuring cells at high static pressures p1, p2, including, for example, overload membranes (US Pat. EP 1 299 701 B1 . DE 10 2006 040 325 A1 or DE 10 2006 057 828 A1 ) or membrane beds ( US 4,458,537 or DE 10 2009 046 229 A1 ).

For overload protection and for supporting the counter body, the two mutually pressure-tight connected counter-body are usually enclosed between two support body.

It has been found that at high pressures, a residual notch stress in the region of the connection or joint between measuring diaphragm and counter-body is problematic. To minimize this notch stress is in the DE 10 2014 109491 A1 proposed to form in each case an additional hydraulic chamber in the connection of counter-body and support body, which communicates via a compensation channel with the measuring chamber. The hydraulic chamber extends in a plane parallel to the measuring diaphragm plane and causes the respective process pressure not only from the measuring chamber on the counter body, but also on the back, namely acting from the hydraulic chambers, acting on the counter body. Since in each case the same pressure prevails in the measuring chamber and the hydraulic chamber, the same pressure acts on the counter body from the end face facing away from the measuring diaphragm and the end face facing the measuring diaphragm.

This means that the forces acting on the counter-body from the end face facing the measuring diaphragm are substantially equal to the forces acting on the counter-body from the end face facing away from the measuring diaphragm. Thus, substantially no resulting forces prevail on the counter body, whereby a pressure-dependent deflection of the counter body is considerably reduced. The achieved by the hydraulic chambers isobaric storage of the counter body thus leads to an increase in the compressive strength.

Furthermore, the isobaric bearing of the counter body leads to a reduction of a systematic error in the measurement signal due to a high static pressure p1, p2. A systematic error could, for example in the case of a capacitive differential pressure measuring cell, be caused by a pressure-related increase in the electrode measuring diaphragm distance and an associated shift in the zero point and / or change in the sensitivity.

An embodiment similar to this embodiment is in the American patent specification US 9274 061 B2 disclosed. However, the arrangements disclosed therein are - in contrast to those in the DE 10 2014 109491 A1 disclosed embodiments - all asymmetrical. Based on these Asymmetry are the disclosed in the US Patent Specifications for reducing the influence of the static pressure p1, p2 on the measurement signal of the differential pressure measuring cell unsuitable.

In order to obtain such a hydraulic chamber between the counter-body and the support body, an additional process step is usually necessary. For example, the end face of the support body and / or counter-body must be specially processed so as to obtain the desired hydraulic chamber. Depending on the type and material of the counter-body and / or support body, such a processing is complicated and requires at least one additional process step.

The invention is based on the object to provide a simple method to obtain a hydraulic chamber in the connection between conventional counter-bodies and supporting bodies.

• – wobei die Messmembran zwischen dem ersten Gegenkörper und dem zweiten Gegenkörper angeordnet und mit beiden Gegenkörpern druckdicht verbunden ist,
• – wobei zwischen der Messmembran und dem ersten Gegenkörper eine erste Messkammer und zwischen der Messmembran und dem zweiten Gegenkörper eine zweite Messkammer gebildet wird,
• – wobei der erste Gegenkörper und erste Stützkörper sowie der zweite Gegenkörper und zweite Stützkörper jeweils einen Druckkanal aufweisen, durch den die erste Messkammer mit einem ersten Druck (p1) und die zweite Messkammer mit einem zweiten Druck (p2) beaufschlagbar ist und
• – wobei der Wandler dazu ausgestaltet ist, ein elektrisches Messsignal aus einer durch die Differenz zwischen dem ersten Druck (p1) und dem zweiten Druck (p2) bedingte Verformung der Messmembran zu erzeugen,

wobei sich das Fügen in folgende Verfahrensschritte unterteilt:

• – Vorfertigung der beiden Gegenkörper und druckdichtes Verbinden der Messmembran mit den beiden Gegenkörpern,
• – Aufbringen eines Fügematerials auf die der Messmembran zugewandte Stirnfläche des ersten Stützkörpers oder auf die der Messmembran abgewandte Stirnfläche des ersten Gegenkörpers und auf die der Messmembran zugewandte Stirnfläche des zweiten Stützkörpers oder auf die der Messmembran abgewandte Stirnfläche des zweiten Gegenkörpers, wobei auf mindestens einer der Stirnflächen das Fügematerial beim Aufbringen so strukturiert wird, dass • die Stirnfläche einen zusammenhängenden, innenliegenden Bereich ohne Fügematerial aufweist, • die Stirnfläche einen zusammenhängenden, den innenliegenden Bereich im Wesentlichen umgebenden außenliegenden Bereich mit Fügematerial aufweist,
• – Druckdichtes Verbinden der jeweils der Messmembran abgewandten Stirnfläche des Gegenkörpers mit der der Messmembran zugewandten Stirnfläche des Stützkörpers, wobei bei der Verbindung von zumindest einem der Gegenkörper mit dem angrenzenden Stützkörper durch den zusammenhängenden innenliegenden Bereich ohne Fügematerial eine hydraulische Kammer zwischen Gegenkörper und Stützkörper ausgebildet wird, wobei die hydraulische Kammer über den Druckkanal mit der Messkammer kommuniziert.

The object is achieved by a method for joining a differential pressure measuring cell, which differential pressure measuring cell comprises: a measuring diaphragm; a transducer, a first and a second counter body, and a first and a second support body,

• Wherein the measuring diaphragm is arranged between the first counter-body and the second counter-body and is pressure-tightly connected to both counter-bodies,
• Wherein a first measuring chamber is formed between the measuring diaphragm and the first counterbody and a second measuring chamber is formed between the measuring diaphragm and the second counterbody,
• - Wherein the first mating body and the first support body and the second mating body and second support body each have a pressure channel through which the first measuring chamber with a first pressure (p1) and the second measuring chamber with a second pressure (p2) can be acted upon and
• Wherein the transducer is configured to generate an electrical measurement signal from a deformation of the measurement membrane caused by the difference between the first pressure (p1) and the second pressure (p2),

wherein the joining is subdivided into the following method steps:

• - prefabrication of the two counter-bodies and pressure-tight connection of the measuring membrane with the two counter-bodies,
• - Applying a joining material on the measuring membrane facing the end face of the first support body or on the measuring membrane facing away from the end face of the first mating body and the measuring membrane facing end face of the second support body or on the measuring membrane facing away from the end face of the second mating body, wherein on at least one of the end faces during application, the joining material is structured in such a way that • the end face has a coherent, inner area without joining material, • the end face has a continuous outer area with joining material substantially surrounding the inner area,
• Pressure-tight connection of the end faces of the counterpart body facing away from the measuring diaphragm, wherein a hydraulic chamber is formed between the counter body and the supporting body when connecting at least one of the counter bodies to the adjoining supporting body through the continuous internal area without joining material, wherein the hydraulic chamber communicates with the measuring chamber via the pressure channel.

In the first step of the method according to the invention, therefore, the two counter-bodies are first prefabricated. During the pressure-tight connection of the measuring diaphragm with the two counter-bodies, the measuring diaphragm is arranged between the two counter-bodies and the measuring chambers are formed. The prefabrication in the first method step also includes the arrangement of all those components between the counter bodies, which are required for the generation or conversion of the measurement signal, such as the membrane electrodes and the transducer.

In the second step of the method according to the invention, the joining material is applied in a structured manner on the end face of a counter body and / or support body. The structuring is carried out in such a way that an internal area communicating with the measuring chamber without joining material is provided on the end face. The joining material is thus applied only on the outer region surrounding the inner region of the end face. The outer region surrounding the inner region extends up to the edge regions of the end face. The end face, on which the joining material is applied in a structured manner, is one of the two end faces in the connecting plane of the first and / or second mating body with the adjacent supporting body. The end face of the mating body and the supporting body is substantially in a plane parallel to the measuring diaphragm plane.

In the method according to the invention, the joining material is applied to the end face of the support body Applied, the pressure-tight connection of the support body with the adjacent counter body takes place in a subsequent process step. This is a point in time which lies before the process step of the pressure-tight connection. In the context of this application, in this case "the end face of the support body facing the measuring diaphragm" is that end face which is provided for connection to the end face of the counter body remote from the measuring diaphragm. The measuring membrane facing the end face of the support body is thus the one which is to be combined in the positioning of the counter body and support body with the measuring membrane facing away from the end face of the counter body.

In the third step of the method according to the invention is formed by the pressure-tight connection of the support body and the counter body based on the inner region without joining material, a hydraulic chamber between the counter body and the support body. The pressure channel, which communicates with the measuring chamber, must lie in the area without joining material.

The advantage of the method according to the invention is that the hydraulic chamber is formed only by the structured application of the joining material and the pressure-tight connection of the support body and the counter body. The hydraulic chamber corresponds to the inner area without joining material. Since the application of the joining material is a common process step in known methods for joining conventional differential pressure measuring cells, no additional process step is required.

This also eliminates a specific structuring of the counter body and / or support body itself, so that standardized counter-body and support body can be used with substantially flat or planar end faces. In contrast to known methods, the joining material is applied in a structured manner, whereby the hydraulic chamber between the counter body and the support body is formed. With the method according to the invention can therefore be obtained in a simple and cost-effective manner, a differential pressure measuring cell with a hydraulic chamber between the counter body and the support body.

In one embodiment of the method according to the invention, the joining material is applied by means of a screen printing process. Since in screen printing process the metering and / or structuring of the joining material is very easily adjustable or controlled, these are particularly suitable for the inventive method. For example, in the screen-printing process, it is possible to use computer-aided methods to produce automatically produced screen-printing matrices. Thus, very precisely defined patterns of joining material can be applied to the end face and a high degree of automation in the production of differential pressure measuring cells can be achieved with a hydraulic chamber by the method according to the invention.

As joining material, in one embodiment of the method according to the invention, a glass solder, adhesive or metallic solder is used.

In a further embodiment of the method according to the invention, the joining material is applied with an approximately constant layer thickness. The approximately constant layer thickness is between 5-50 micrometers. The glass solder is used in particular in the joining of differential pressure measuring cells, which are based on micro-electro-mechanical systems (MEMS). In the case of a differential pressure measuring cell based on a MEMS sensor and a glass solder, the layer thickness of the joining material is substantially between 10-20 micrometers.

In a further embodiment of the method according to the invention, the first and the second counter-body are each connected in a pressure-tight manner to the adjoining support body with a substantially homogeneous contact pressure distribution. By a contact pressure, the joining material is reduced in the direction perpendicular to the end face and increased in a plane parallel to the end face. The joining material should therefore be applied in a structured manner so that the enlargement of the joining material in the plane parallel to the end face is taken into account, so that the hydraulic chamber is not completely filled with joining material during the joining. To achieve this, the contact pressure must be adjustable, and the expansion of the joining material under the action of the contact pressure must be known or calculable. If the contact pressure distribution is substantially homogeneous, a substantially constant layer thickness of the joining material is achieved after the pressure-tight bonding.

In a particularly advantageous embodiment of the method according to the invention, the joining material is structured on two end faces, so that the first and the second counter-body are each connected in a pressure-tight manner to the adjacent supporting body to form a hydraulic chamber. In this particularly preferred embodiment can be obtained for the typical application that both process pressures are very high, with the joining method according to the invention a differential pressure cell of particularly high pressure resistance and overload protection and accuracy at high pressure on both sides.

In a development of this embodiment, the joining material is structured essentially identically on both end faces.

In general, the counter body and / or the support body on at least one axis of symmetry, wherein the counter body and / or the support body is substantially symmetrical with respect to the axis of symmetry. The axis of symmetry may be, for example, the mirror axis of a mirror symmetry, or else the axis of rotation of a rotational symmetry. The symmetry axis can lie in the plane of the end face, or be perpendicular to the end face. In an advantageous development of the method, the joining material is structured on at least one of the end surfaces in such a way that the inner region without joining material is arranged substantially symmetrically about at least one axis of symmetry. The axis of symmetry is thus a common axis of symmetry of the support body and / or counter-body and the inner region without joining material.

In a further embodiment of the method according to the invention, the joining material is patterned on at least one of the end surfaces such that the region without joining material is of a cross-shaped surface, and wherein the pressure channel communicating with the measuring chamber is arranged in the center of the cross-shaped surface. The area without joining material of cross-shaped surface is formed by two intersecting and mutually perpendicular struts without joining material. The struts do not necessarily have the same length and / or width.

An obvious further development of this embodiment of the method according to the invention provides, in structuring several struts without joining material. For example, any even number of struts can be provided without joining material which intersect at an intersection and extend radially away from the intersection.

In this embodiment, a differential pressure measuring cell with a hydraulic chamber is obtained by the method, distributed over a circular area radial sections of the hydraulic chamber are arranged. The radius of the circular surface is defined as the maximum length of the radial struts. The pressure channel is arranged in the center of the circular area. The hydraulic areas in the form of radial struts are distributed over the entire circular area. At the same time, intermediate regions exist between the radial struts in which the mating body is completely joined with the adjoining support body. In the intermediate regions, therefore, there is a rigid connection between the mating body and the support body via the joining material. Due to the rigid connection in the intermediate regions, the counter body is fully supported on the support body in the intermediate regions. The joining method thus makes it possible to distribute hydraulic and supporting share evenly in the connection plane between the mating body and support body and thus combine advantageous.

In this way, a differential pressure measuring cell is obtained in which there are distributed over a substantially circular area both supporting and hydraulic shares. The differential pressure measuring cell thus obtained is therefore both of high stability with high one-sided pressure load and at the same time of high stability and accuracy with high pressure on both sides.

It is advantageous if the area without joining material is at least partially round. In this way, a sectionally round hydraulic chamber is achieved. This is helpful for reducing stress peaks or discontinuities in the stress distribution.

In a further embodiment of the method according to the invention, the structuring of the joining material therefore provides a substantially circular area without joining material. The joining material is patterned on at least one of the end surfaces so that the region without joining material is of elliptic or circular surface, and wherein the pressure channel communicating with the measuring chamber is located in the center of the elliptical or circular surface.

• – wobei die Messmembran zwischen dem ersten Gegenkörper und dem zweiten Gegenkörper angeordnet und mit beiden Gegenkörpern druckdicht verbunden ist,
• – wobei zwischen der Messmembran und dem ersten Gegenkörper eine erste Messkammer und zwischen der Messmembran und dem zweiten Gegenkörper eine zweite Messkammer gebildet ist,
• – wobei der erste Gegenkörper und Stützkörper und der zweite Gegenkörper und Stützkörper jeweils einen Druckkanal aufweisen, durch den die erste Messkammer mit einem ersten Druck (p1) und die zweite Messkammer mit einem zweiten Druck (p2) beaufschlagbar ist und
• – wobei der Wandler dazu ausgestaltet ist, ein elektrisches Messsignal aus einer durch die Differenz zwischen dem ersten Druck (p1) und dem zweiten Druck (p2) bedingte Verformung der Messmembran zu erzeugen;

wobei jeweils die der Messmembran abgewandte Stirnfläche des Gegenkörpers mit der der Messmembran zugewandten Stirnfläche des Stützkörpers druckdicht verbunden ist,
und wobei mindestens einer der beiden Gegenkörper mit dem angrenzenden Stützkörper unter Bildung einer hydraulischen Kammer verbunden ist.The invention includes a differential pressure measuring cell, wherein the differential pressure measuring cell was obtained from the method according to the invention, comprising;
a measuring membrane; a transducer, a first and a second counter body, and a first and a second support body,

• Wherein the measuring diaphragm is arranged between the first counter-body and the second counter-body and is pressure-tightly connected to both counter-bodies,
• Wherein a first measuring chamber is formed between the measuring diaphragm and the first counterbody and a second measuring chamber is formed between the measuring diaphragm and the second counterbody,
• - Wherein the first mating body and support body and the second mating body and support body each have a pressure channel through which the first measuring chamber with a first pressure (p1) and the second measuring chamber with a second pressure (p2) can be acted upon and
• - wherein the transducer is adapted to generate an electrical measurement signal from a caused by the difference between the first pressure (p1) and the second pressure (p2) deformation of the measuring diaphragm;

wherein each of the measuring membrane facing away from the end face of the counter body is pressure-tightly connected to the measuring membrane facing end face of the support body,
and wherein at least one of the two counter-bodies is connected to the adjacent support body to form a hydraulic chamber.

In a preferred embodiment of the invention, the diameter of the hydraulic chamber deviates at most 20% from the diameter of the measuring diaphragm (i.e., the diameter of the measuring diaphragm in the region of the measuring chamber). Preferably, the diameter of the hydraulic chamber is equal to the diameter of the measuring diaphragm. If the cross-sectional area of the hydraulic chamber matches (i.e., does not differ by more than 20%) the diameter of the measuring diaphragm, the uniform pressure distribution translates into a balance of forces. This means that the forces acting on the counter-body from the end face facing the measuring diaphragm are substantially equal to the forces acting on the counter-body from the end face facing away from the measuring diaphragm. Thus, there are essentially no resulting forces on the counter body.

In one embodiment of the invention, the support body and / or the counter body consists of a ceramic material.

In a further embodiment, the support body and / or the counter body consists essentially of silicon (Si), of an amorphous or crystalline oxide (SiO 2), carbide (SiC) and / or nitride (Si 3 N 4) of the silicon and / or of an amorphous or crystalline oxide (Al 2 O 3) and / or nitride of aluminum (AlN). The carbide of silicon, which can be present in many energetically almost equivalent polytopes, is suitable because of its high hardness. On the other hand, silicon nitride has a slightly lower hardness, but has a high breaking strength in combination with a low coefficient of thermal expansion and a relatively small modulus of elasticity.

On the basis of the choice of the combination of materials, the modulus of elasticity of the components of the differential pressure measuring cell can be adjusted. In a further development of the invention, the modulus of elasticity of the support body is adjusted so that it is equal to or greater than the modulus of elasticity of the counter body. As an upper limit, the modulus of elasticity of the support body in this development should be at most three times as large as the modulus of elasticity of the counterpart body. In this embodiment, the support body is thus at least as stable as the counter body.

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

1a , b: An embodiment of the method according to the invention and the differential pressure measuring cell obtained by the method according to the invention

2a , b: A further embodiment of the method according to the invention and the differential pressure measuring cell obtained by the method according to the invention

1a is a plan view of the measuring membrane 2 opposite end face 12a of the first mating body 41 (left) and the measuring membrane 2 facing end face 13a of the first support body 51 (right) shown. The method step shown here is the application of the structured joining material FM to that of the measuring membrane 2 facing end face 13a of the first support body 51 , The first method step of the method according to the invention (the prefabrication of the two counter bodies 41 . 42 and the pressure-tight connection of the measuring diaphragm 2 with the two counter bodies 41 . 42 ) has preceded the process step of applying the joining material FM. The measuring diaphragm ME thus lies in the connection plane of the two counter-bodies 41 . 42 , The to the faces 12a . 12b vertical side surfaces of the mating body 41 . 42 are shown as hatched areas. In the center of the measuring membrane 2 facing end face 13a of the first support body 51 is the pressure channel 7 arranged over which the measuring chamber 61 can be acted upon by the pressure p1.

The joining material FM is applied to the measuring membrane 2 zugwandten face 13a of the support body 51 patterned, leaving an internal area 31 without joining material FM is formed. This inside area 31 is of cruciform surface. In the center of the radial struts of the cross-shaped surface is the one with the measuring chamber 61 communicating pressure channel 7 arranged. The outer, the inner area 31 essentially surrounding area 32 without joining material FM is shown here as a dotted area. In the pressure-tight connection of the measuring membrane 2 facing end face 13a of the support body 51 with the measuring membrane 2 opposite end face 12a of the opposite body 41 becomes the hydraulic chamber due to the structuring of the joining material FM according to the invention 8th formed in the areas without joining material FM. The process The pressure-tight connection is indicated by the dashed arrows in FIG 1a indicated.

1b is a schematic side view of a cross section of the differential pressure measuring cell according to the invention 1 , which with the inventive method 1a was obtained. For orientation were in 1a , b is the straight AB (dashed) line in the hydraulic chamber obtained in the pressure-tight connection 8th located.

In this embodiment, only in one end face 13a structured the joining material FM. It is therefore only a hydraulic chamber 8th with a diameter dS between the first mating body 41 and the first support body 51 , Nonetheless, the components described below may also be part of a differential pressure measuring cell according to the invention 1 with two hydraulic chambers 8th between the opposing body 41 . 42 and supporting body 51 . 52 be. It should be noted that the schematic representation shown here is by no means true to scale.

The measuring membrane 2 , which has a diameter dM, is between the two counter bodies 41 . 42 arranged. The opposing bodies 41 . 42 are with the measuring diaphragm 2 forming the measuring chambers 61 . 62 pressure-tight connected to each other. The two measuring chambers 61 . 62 can each have a pressure channel 7 with the pressures p1 and p2 be applied.

The differential pressure measuring cell 1 further comprises a capacitive transducer (not shown here) which receives one of a difference of the two pressures | p1 - p2 | dependent deflection of the measuring diaphragm 2 converts into an electrical signal. For this purpose, the two counter-bodies 41 . 42 For example, each at its diaphragm-side end face 11a . 11b at least one measuring electrode 10a . 10b on, with the measuring diaphragm 2 both sides a membrane electrode 14a . 14b having a measuring electrode 10a . 10b is facing. In a simple embodiment of the capacitive converter, the pressure difference | p1 - p2 | to be measured results from the difference between the reciprocal values of the capacitances between in each case one measuring electrode 10a . 10b and the opposite membrane electrode 14a . 14b , The sum of the capacity inversion values can be used to determine the static pressure p1, p2, to which the pressure difference | p1 - p2 | is superimposed. To increase the accuracy of measurement, the end faces of the counter body 41 . 42 each have a circular disk-shaped central electrode and a surrounding, in particular capacitance equal, ring electrode. Details of the wiring of such a capacitive transducer are known and, for example, in EP 1 883 797 B1 disclosed.

For detecting the static pressure p1, p2, at least one further capacitive transducer can be provided, which in each case has an electrode at the measuring diaphragm 2 opposite end face 12a . 12b of the opposite body 41 . 42 or the measuring membrane 2 facing end face 13a . 13b of the support body 51 . 52 having. Similarly, a resistive transducer for detecting the static pressure p1, p2 may be provided, wherein the support body 51 . 52 or counterbody 41 . 42 in this case has deformation-dependent resistance elements. The latter may for example comprise strain gauges, wherein in the case of a differential pressure measuring cell 1 comprising a semiconductor material, piezoresistive resistive elements are preferable.

2a essentially shows the same thing as us 1a , namely the structuring of the joining material FM in the measuring membrane 2 facing end face 13a of the support body 51 , In contrast to 1a Here, the joining material FM is structured so that the inner area 31 without joining material FM is of circular area. Also, here an axis of symmetry SA is shown, around which the inner area 31 without joining material FM is arranged substantially symmetrically. In the case of a circular interior area 31 There are also other symmetry axes SA, which are not shown here.

2 B is (analogous to 1b ) is a schematic side view of a cross section of the differential pressure measuring cell according to the invention 1 , which with the inventive method 1a was obtained. In this embodiment, the structuring of the joining material FM in two end faces 13a . 13b two hydraulic chambers 8th receive.

LIST OF REFERENCE NUMBERS

1

 Differential pressure measuring cell

2

 measuring membrane

31

 Internal area without joining material

32

 Outboard area with joining material

41

 first counter body

42

 second counter body

51

 first support body

52

 second support body

61

 first measuring chamber

62

 second measuring chamber

7

 pressure channel

8th

 hydraulic chamber

10a

 measuring electrode

10b

 measuring electrode

11a

 the measuring membrane facing end face of the first counter body

11b

 the measuring membrane facing end face of the second counter body

12a

 the measuring membrane facing away from the end face of the first counter body

12b

 the measuring membrane facing away from the end face of the second counter body

13a

 the measuring diaphragm facing end face of the first support body

13b

 the measuring membrane facing end face of the second support body

14a

 membrane electrode

14b

 membrane electrode

p1

 first pressure

p2

 second pressure

FM

 Add material

dS

 maximum diameter of the hydraulic chamber

dm

 Diameter of the measuring diaphragm

ME

 Measuring membrane level

SA

 axis of symmetry

It

 Elastic modulus of the support body

Eg

 Young's modulus of the counter body

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10394943 B3 [0002]
• EP 1299701 B1 [0004]
• DE 102006040325 A1 [0004]
• DE 102006057828 A1 [0004]
• US 4458537 [0004]
• DE 102009046229 A1 [0004]
• DE 102014109491 A1 [0006, 0009]
• US 9274061 B2 [0009]
• EP 1883797 B1 [0045]

Claims (15)

Method for joining a differential pressure measuring cell ( 1 ), which differential pressure measuring cell ( 1 ), comprising: a measuring membrane ( 2 ); a transducer, a first and a second counter body ( 41 . 42 ), and a first and a second support body ( 51 . 52 ), - whereby the measuring membrane ( 2 ) between the first counterbody ( 41 ) and the second counter body ( 42 ) and with both counter bodies ( 41 . 42 ) is connected pressure-tight, - wherein between the measuring diaphragm ( 2 ) and the first counterbody ( 41 ) a first measuring chamber ( 61 ) and between the measuring membrane ( 2 ) and the second counter body ( 42 ) a second measuring chamber ( 62 ) is formed, - wherein the first counter body ( 41 ) and first support body ( 51 ) as well as the second counterbody ( 42 ) and second support body ( 52 ) each have a pressure channel ( 7 ) through which the first measuring chamber ( 61 ) with a first pressure (p1) and the second measuring chamber ( 61 ) is acted upon with a second pressure (p2) and - wherein the transducer is configured to an electrical measurement signal from a by the difference between the first pressure (p1) and the second pressure (p2) caused deformation of the measuring diaphragm ( 2 ), wherein the joining is subdivided into the following method steps: - prefabrication of the two counter bodies ( 41 . 42 ) and pressure-tight connection of the measuring membrane ( 2 ) with the two counter bodies ( 41 . 42 ), - applying a joining material (FM) to the measuring membrane ( 2 ) facing end face ( 13a ) of the first support body ( 51 ) or on the measuring membrane ( 2 ) facing away from the end face ( 12a ) of the first counterbody ( 41 ) and on the measuring membrane ( 2 ) facing end face ( 13b ) of the second support body ( 52 ) or on the measuring membrane ( 2 ) facing away from the end face ( 12b ) of the second counter body ( 42 ), wherein on at least one of the end faces ( 12a ; 12b ; 13a ; 13b ) the joining material (FM) is structured during application in such a way that 12a ; 12b ; 13a ; 13b ) a contiguous, inner area ( 31 ) without joining material (FM), • the end face ( 12a ; 12b ; 13a ; 13b ) a contiguous, the inner area ( 31 ) substantially surrounding external area ( 32 ) with joining material (FM), - pressure-tight connection of each of the measuring membrane ( 2 ) facing away from the end face ( 12a . 12b ) of the counterbody ( 41 . 42 ) with the measuring membrane ( 2 ) facing end face ( 13a . 13b ) of the supporting body ( 51 . 52 ), wherein in the connection of at least one of the counter bodies ( 41 ; 42 ) with the adjacent support body ( 51 ; 52 ) through the contiguous interior area ( 31 ) without joining material (FM) a hydraulic chamber ( 8th ) between counter-bodies ( 41 ; 42 ) and supporting body ( 51 ; 52 ), wherein the hydraulic chamber ( 8th ) via the pressure channel ( 7 ) with the measuring chamber ( 61 ; 62 ) communicates. The method of claim 1, wherein the joining material (FM) is applied by a screen printing method. A method according to claim 1 or 2, wherein a glass solder, adhesive or metallic solder is used as the joining material (FM). Method according to at least one of the preceding claims, wherein the joining material (FM) is applied with an approximately constant layer thickness between 5-50 micrometers. Method according to at least one of the preceding claims, wherein the first counterbody ( 41 ) and the second counter body ( 42 ) each with the adjacent support body ( 51 . 52 ) are connected pressure-tight with a substantially homogeneous contact pressure distribution. Method according to at least one of the preceding claims, wherein the joining material (FM) on two end faces ( 12a ; 12b ; 13a ; 13b ), so that the first counterbody ( 41 ) and the second counter body ( 42 ) each with the adjacent support body ( 51 . 52 ) to form a hydraulic chamber ( 8th ) are connected pressure-tight. A method according to claim 6, wherein the joining material (FM) on both faces ( 12a ; 12b ; 13a ; 13b ) is structured substantially identically. Method according to at least one of the preceding claims, wherein counter-bodies ( 41 . 42 ) and / or supporting body have at least one axis of symmetry (SA), and wherein the joining material (FM) on at least one of the end faces ( 12a ; 12b ; 13a ; 13b ) is structured such that the inner area ( 31 ) without joining material (FM) is arranged essentially symmetrically about the axis of symmetry (SA). Method according to at least one of the preceding claims, wherein the joining material (FM) is arranged on at least one of the end faces ( 12a ; 12b ; 13a ; 13b ) is structured so that the area without joining material ( 31 ) of cross-shaped surface, and wherein the with the measuring chamber ( 2 ) communicating pressure channel ( 7 ) is arranged in the center of the cross-shaped surface. Method according to at least one of the preceding claims, wherein the joining material (FM) is arranged on at least one of the end faces ( 12a ; 12b ; 13a ; 13b ) is structured so that the area is without joining material of elliptical or circular area, and wherein the area with the measuring chamber ( 2 ) communicating pressure channel ( 7 ) is arranged in the center of the elliptical or circular surface. Differential pressure measuring cell ( 1 ) obtained from a method according to at least one of the preceding claims 1-10; a measuring membrane ( 2 ); a transducer, a first and a second counter body ( 41 . 42 ), and a first and a second support body ( 51 . 52 ), - whereby the measuring membrane ( 2 ) between the first counterbody ( 41 ) and the second counter body ( 42 ) and with both counter bodies ( 41 . 42 ) is connected pressure-tight, - wherein between the measuring diaphragm ( 2 ) and the first counterbody ( 41 ) a first measuring chamber ( 61 ) and between the measuring membrane ( 2 ) and the second counter body ( 42 ) a second measuring chamber ( 61 ), wherein the first counterbody ( 41 ) and first support body ( 51 ) and the second counter body ( 42 ) and second support body ( 52 ) each have a pressure channel ( 7 ) through which the first measuring chamber ( 61 ) with a first pressure (p1) and the second measuring chamber ( 62 ) is acted upon by a second pressure (p2) and - wherein the transducer is adapted to generate an electrical measurement signal from a caused by the difference between the first pressure (p1) and the second pressure (p2) deformation of the measuring diaphragm; each of the measuring membrane ( 2 ) facing away from the end face ( 12a . 12b ) of the counterbody ( 41 . 42 ) with the measuring membrane ( 2 ) facing end face ( 13a . 13b ) of the supporting body ( 51 . 52 ) is connected pressure-tight, and wherein at least one of the two counter-body ( 41 ; 42 ) with the adjacent support body ( 51 ; 52 ) to form a hydraulic chamber ( 8th ) connected is. Differential pressure measuring cell ( 1 ) according to claim 11, wherein the hydraulic chamber ( 8th ) has a maximum diameter (dS), wherein the diameter (dS) deviates at most 20% from the diameter of the measuring diaphragm (dM), and wherein preferably the diameter (dS) of the hydraulic chamber (dS) 8th ) is equal to the diameter of the measuring diaphragm (dM). Differential pressure measuring cell ( 1 ) according to claim 11 or 12, wherein the counterbody ( 41 ; 42 ) and / or the supporting body ( 51 ; 52 ) consists of a ceramic material. Differential pressure measuring cell ( 1 ) according to at least one of the preceding claims 11-13, wherein the counterbody ( 41 ; 42 ) and / or the supporting body ( 51 ; 52 ) - of silicon (Si), - of an amorphous or crystalline oxide of silicon (SiO2), amorphous or crystalline carbide (SiC) of silicon and / or amorphous or crystalline nitride (SiN) of silicon, - and / or of an amorphous or crystalline oxide of aluminum (Al 2 O 3) and / or nitride of aluminum (AlN). Differential pressure measuring cell ( 1 ) according to at least one of the preceding claims 11-14, wherein the modulus of elasticity (Es) of the supporting body ( 51 ; 52 ) equal to or greater than the elastic modulus (Eg) of the counter body ( 41 ; 42 ), wherein the elastic modulus (Es) of the supporting body ( 51 ; 52 ) at most three times as large as the elastic modulus (Eg) of the counter body ( 41 ; 42 ).

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