DE102020121583A1 - differential pressure sensor - Google Patents

Abstract

The invention relates to a differential pressure sensor (1) for determining the differential pressure of two pressures (p1, p2) with a measuring mechanism (2) and a converter chamber (3), with a coplanar double membrane system on or in an end region of the measuring mechanism (2) facing the process (4) is provided with two double membranes (4a, 4b) and wherein a differential pressure measuring cell (12) with a pressure-sensitive element (13) is arranged in the converter chamber (3), the two double membranes (4a, 4b) each consisting of a separating membrane ( 5a, 5b) and an overload diaphragm (6a, 6b) arranged behind the separating diaphragm (5a, 5b) in the direction of the pressure effect, with a first pressure chamber (7a) between the first separating diaphragm (5a) and the first overload diaphragm (6a) and between of the first overload diaphragm (6a) and the base body (9), a first additional pressure chamber (8a) is formed, with a second pressure chamber between the second separating diaphragm (5b) and the second overload diaphragm (6b). chamber (7b) and a second additional pressure chamber (8b) is formed between the second overload diaphragm (6b) and the base body (9), with the first additional pressure chamber (8a) having a first connecting capillary (10a) and the second additional pressure chamber (8b) having a second is assigned to the connecting capillary (10b), the two connecting capillaries (10a, 10b) transmitting the pressure hydraulically to the converter chamber (3), and wherein - to protect the pressure-sensitive element (13) from overpressure on one side - the first additional pressure chamber (8a) has a first auxiliary capillary (11a) and the second additional pressure chamber (8b) is assigned a second auxiliary capillary (11b), with the first pressure chamber (7a) being assigned a third auxiliary capillary (11c) and the second pressure chamber (7b) being assigned a fourth auxiliary capillary (11d), wherein, for the purpose of hydraulic coupling, the first auxiliary capillary (11a) is connected to the fourth auxiliary capillary (11d) and the second auxiliary capillary (11b) is connected to the third auxiliary capillary (11c ) is connected, the connection points being arranged in each case in the converter chamber (3).

Description

The invention relates to a coplanar differential pressure sensor for determining the differential pressure of two pressures. The differential pressure sensor according to the invention is preferably used in the field of automation technology.

Differential pressure gauges are used in particular for the continuous measurement of pressure differences in measurement media, e.g. in liquids, vapours, gases and dust. For example, the level of a medium in a container or the flow of a medium through a pipe can be determined from the differential pressure.

A silicon chip is usually used as the pressure-sensitive element. In order to achieve good measuring sensitivity, a differential pressure sensor preferably works in a range that is close to a critical limit value for the pressure (nominal pressure). If the critical limit is exceeded, there is a risk that the chip will be destroyed. Since silicon chips, in particular, have a relatively low overload resistance, overload protection is usually assigned to a differential pressure sensor. This is preferably designed in such a way that it affects the measurement sensitivity and the measurement accuracy of the pressure-sensitive element as little as possible.

From the DE 3 222 620 A1 a pressure difference measuring device has become known which has a pressure measuring transducer device protected against overload. The measuring device has a central receiving body which forms an antechamber on two opposite sides between a membrane bed and a separating membrane. In the receiving body, an additional chamber is provided in each case behind the side facing away from the membrane bed, which is delimited by a prestressed additional membrane. Inside the receiving body there is also a measuring chamber, which is divided into two sub-chambers by the pressure sensor device. Each of the two partial chambers of the measuring chamber is connected to one of the two antechambers via a respective connecting channel. Each of the two connecting channels is connected to one of the two additional chambers via an additional channel.

If the device is exposed to a differential pressure below or in the range of the nominal differential pressure value, then this differential pressure is transmitted to the pressure sensor device via the connecting channels. The additional membranes develop a small effect, which is negligible in a first approximation. If the pressure difference exceeds the nominal pressure difference value by a predetermined value as a result of an overload, the pressure transmitter liquid located below it is pressed into the antechamber assigned to it on the high-pressure side of the separating membrane. The liquid that is pushed out reaches the auxiliary diaphragm on the low-pressure side via the connection channel and the auxiliary channel, causing it to lift. Thus, in the event of an overload, the liquid that is pressed out on the high-pressure side under the separating diaphragm is under the lifting additional diaphragm on the low-pressure side. Consequently, an overload of the pressure sensor device is avoided. In the case of the German patent application, the converter chamber is integrated into the measuring mechanism.

From the WO 2018/165122 A1 a coplanar differential pressure sensor has become known, in which the pressure inputs with separating membrane and overload membrane are arranged in one plane - specifically in the end area facing the process - and not on opposite, parallel planes as in the aforementioned German patent application. It is a so-called double membrane system. The advantage of double membrane systems lies in the significantly lower oil volume that is required for the hydraulic operation of the differential pressure sensor. In addition, the pressure-loaded center membrane weld can be dispensed with here, so that the measuring mechanism can be made in one piece. As in the previously mentioned patent application, the overload protection is also arranged in the measuring mechanism in this known solution, ie the crossed capillaries are located in the measuring mechanism. The converter chamber is placed directly on the measuring mechanism or integrated into the measuring mechanism.

The known solutions have several disadvantages: Since the crossed hydraulic pressure feedthroughs are arranged in the measuring mechanism, e.g. in the known coplanar design, for the purpose of oil filling, externally exposed bores are required, which are closed after filling. The closure areas are potential corrosion weak points. In addition, the holes are quite long, which has a negative impact on manufacturing costs. Long bores also inevitably require a larger oil volume, which in turn makes it difficult to implement overload protection in the measuring mechanism. Since defined distances between the pressure ducts must be maintained, there are limits to minimizing the dimensions of the measuring unit.

The object of the invention is to propose a pressure sensor with overload protection and reduced oil volume. At this point, the term "oil volume" is chosen because it is the hydraulic transmission fluid usually an almost incompressible oil, for example a silicone oil.

The task is solved by a coplanar differential pressure sensor for determining the differential pressure of two pressures with a measuring mechanism and a converter chamber. These are preferably separate components. A differential pressure measuring cell with a pressure-sensitive element is arranged in the converter chamber. The pressure-sensitive element is a silicon chip, for example.

A coplanar double membrane system with two double membranes is provided on or in an end area of the measuring unit facing the process. Each of the two double diaphragms consists of a separating diaphragm and an overload diaphragm arranged behind the separating diaphragm in the direction of the pressure effect. A first pressure chamber is formed between the first separating diaphragm and the first overload diaphragm, and a first additional pressure chamber is formed between the first overload diaphragm and the base body. A second pressure chamber is formed between the second separating diaphragm and the second overload diaphragm, and a second additional pressure chamber is formed between the second overload diaphragm and the base body. A first connection capillary is assigned to the first additional pressure chamber and a second connection capillary is assigned to the second additional pressure chamber. The pressure is transmitted hydraulically to the pressure-sensitive element via the two connecting capillaries.

To protect the pressure-sensitive element from overpressure on one side, a first auxiliary capillary is assigned to the first additional pressure chamber and a second auxiliary capillary is assigned to the second additional pressure chamber. Furthermore, a third auxiliary capillary is associated with the first pressure chamber and a fourth auxiliary capillary is associated with the second pressure chamber. For the purpose of hydraulic coupling, the first auxiliary capillary is connected to the fourth auxiliary capillary and the second auxiliary capillary is connected to the third auxiliary capillary, with the connection points/intersections being arranged in the converter chamber.

Incidentally, the measuring mechanism is housed in the process connection, and the converter chamber is integrated in the housing adapter.

• - Das Messwerk ist einteilig ausgestaltet.
• - Das Messwerk hat einen relativ einfachen und in weiten Teilen symmetrischen bzw. vollsymmetrischen Aufbau.
• - Kosteneinsparungen werden beim Messwerk, insbesondere durch Materialeinsparung (kleine Dimensionen) und infolge einer vereinfachten Fertigung und Bearbeitung erreicht; die Bohrungen können z.B. kostengünstig durch Erodieren hergestellt werden.
• - Messwerk und Wandlerkammer haben einen gewissen Abstand voneinander. Da in diesem Zwischenbereich bevorzugt nur parallele Kapillaren verlaufen, kann dieser Zwischenbereich klein dimensioniert sein.
• - Messwerk und Wandlerkammer sind - zumindest in der Ausgestaltung ohne Zwischenmodul - nur über die Verbindungskapillaren und die Hilfskapillaren (6-Rohr-System) gekoppelt. Hierdurch ist eine gute mechanische und thermische Entkopplung zwischen Messwerk und Wandlerkammer sichergestellt.
• - Die Kreuzung der Hilfskapillaren erfolgt in der Wandlerkammer bzw. die Verbindungsstellen der Hilfskapillaren liegen in der Wandlerkammer. - Druckdynamisch erfolgt der Anschluss an die Wandlerkammer über eine Reihenschaltung: Ein einseitig auftretender Überdruck auf der Hochdruckseite wird zuerst über die entsprechenden Hilfskapillaren auf die Rückseite der Überlastmembrane der Niederdruckseite geleitet und dann auf die Verbindungskapillaren, die direkt zur Wandlerkammer führen. Dies hat erhebliche Vorteile bezüglich des Druckdynamikschutzes des drucksensitiven Elements, das übrigens auch als Primärsensorelement bezeichnet wird. Erst, wenn der Überlastschutz gegriffen hat, und der Druck unterhalb des kritischen Grenzwertes liegt, werden die Drücke an das drucksensitive Element übertragen. Durch Variation der Kapillardurchmesser oder durch Zusatzelemente, wie z.B. den Druck bremsende Sinterelemente, lässt sich dieser Vorteil noch verstärken. Dies wird an einer nachfolgenden Stelle noch näher beschrieben.
• - Aufgrund des fast nicht Vorhandenseins eines Ölvolumens in den Zusatzdruckkammern im normalen Messbetrieb (die Überlastmembranen liegen im normalen Messbetrieb zumindest näherungsweise an dem Gehäuse an) ist das Ölvolumen gering.
• - Weitere Reduktion des benötigten Ölvolumens, da die üblicherweise relativ langen Befüllungsbohrungen und Querbohrungen im Messwerk entfallen. Die Befüllung erfolgt - gemäß einer nachfolgend noch näher beschriebenen bevorzugten Ausgestaltung - über zumindest eine Befüllungsöffnung in der Wandlerkammer. Somit entfällt die korrosionsanfällige Befüllungsöffnung bzw. das korrosionsanfällige Verschlusselement am Messwerk.

The solution according to the invention has the following advantages:

• - The measuring mechanism is designed in one piece.
• - The measuring unit has a relatively simple and largely symmetrical or fully symmetrical structure.
• - Cost savings are achieved with the measuring mechanism, in particular through material savings (small dimensions) and as a result of simplified manufacture and processing; the bores can be produced inexpensively, for example, by eroding.
• - Measuring mechanism and converter chamber have a certain distance from each other. Since preferably only parallel capillaries run in this intermediate area, this intermediate area can be of small dimensions.
• - Measuring mechanism and converter chamber are - at least in the embodiment without an intermediate module - coupled only via the connecting capillaries and the auxiliary capillaries (6-tube system). This ensures good mechanical and thermal decoupling between the measuring mechanism and the converter chamber.
• - The crossing of the auxiliary capillaries takes place in the converter chamber or the connection points of the auxiliary capillaries are in the converter chamber. - In terms of pressure dynamics, the connection to the converter chamber is made via a series connection: A one-sided overpressure on the high-pressure side is first routed via the corresponding auxiliary capillaries to the back of the overload diaphragm on the low-pressure side and then to the connecting capillaries, which lead directly to the converter chamber. This has considerable advantages with regard to the pressure dynamics protection of the pressure-sensitive element, which is also referred to as the primary sensor element. The pressures are only transmitted to the pressure-sensitive element when the overload protection has taken effect and the pressure is below the critical limit value. This advantage can be increased even further by varying the capillary diameter or by using additional elements, such as sintered elements that slow down the pressure. This is described in more detail at a later point.
• - Due to the almost non-existent oil volume in the additional pressure chambers during normal measuring operation (the overload diaphragms are at least approximately in contact with the housing during normal measuring operation), the oil volume is low.
• - Further reduction of the oil volume required, since the usually relatively long filling holes and cross holes in the measuring mechanism are no longer required. According to a preferred embodiment described in more detail below, the filling takes place via at least one filling opening in the converter chamber. As a result, the corrosion-prone filling opening or the corrosion-prone closure element on the measuring mechanism is no longer required.

The measuring mechanism and the converter chamber are preferably not only separate components, but the measuring mechanism and converter chamber are also spatially separated or spaced apart from one another. This allows the measuring unit and differential pressure measuring cell in the converter chamber to be mechanically and thermally decoupled from one another. The separation between the two components is designed to be pressure-resistant and gas-tight.

Due to the reduced oil volume, the measurement error caused by the temperature gradient is relatively small. Furthermore, due to the smaller oil volume, smaller diaphragms are also possible. Since the oil volume is relatively small, it can be shifted from the high-pressure side to the low-pressure side within a short time if overpressure occurs. This is very important for realizing a working coplanar sensor. Furthermore, when using smaller membranes, smaller measuring ranges can be covered. Small measuring ranges, in turn, allow the activation/deflection of the separating membranes to be kept low, which is associated with smaller measuring errors.

In general it can be said that to protect the pressure-sensitive element against excess pressure, the series connection ensures that an excess pressure occurring on one side on the pressure-sensitive element is limited in such a way that destruction of the pressure-sensitive element is ruled out.

According to one embodiment of the differential pressure sensor according to the invention, the additional membranes are prestressed in such a way that they rest positively or non-positively and essentially over the entire surface on the base body and only lift off the base body when a predetermined critical limit pressure is exceeded. possibly At least one hydraulic channel is provided in the membrane beds and/or the corresponding rear sides of the overload membranes. This ensures that the overload or overpressure protection is only activated when the pressure to be measured is so high that there is a risk of the pressure-sensitive element being destroyed. A process membrane / separating membrane, which can be used, inter alia, in connection with the solution according to the invention is, for example, in US 10,656,039 B2 described.

Furthermore, it is provided that the connecting capillaries and the auxiliary capillaries run essentially parallel to the longitudinal axis of the differential pressure sensor, starting from the measuring unit. In particular, the auxiliary capillaries show a change of direction in the converter chamber, so that the connection points or the intersections of the auxiliary capillaries described above lie in the converter chamber. In this configuration, the change of direction and the crossing are preferably implemented by appropriately arranged transverse bores in the relatively small-sized converter chamber.

One embodiment provides that a block of material is arranged in the intermediate area between the measuring mechanism and the converter chamber. The capillaries running lengthwise and crosswise in the material block are capillary bores. Capillary tubes are preferred when the block of material is missing. Furthermore, it is provided that the connecting capillaries and/or the auxiliary capillaries arranged in the measuring mechanism and in the converter chamber are capillary bores.

In particular, the converter chamber has two connecting capillaries and four auxiliary capillaries on its end region facing the process, which are preferably arranged parallel to one another and which are essentially congruent with the connecting capillaries and auxiliary capillaries designed as capillary bores or capillary tubes, possibly in the material block and/or in the area facing away from the process of the measuring mechanism.

In order to ensure that an overload is limited before it reaches the pressure-sensitive element, an advantageous embodiment of the differential pressure sensor according to the invention proposes that the connecting capillaries and/or the auxiliary capillaries be designed and/or dimensioned in such a way that an overpressure that is above the specified critical limit pressure compensated by the overload protection before the overpressure is transmitted to the differential pressure measuring cell. In order to additionally protect the pressure-sensitive element from pressure peaks, dynamic brakes are built into the connecting lines/connecting capillaries, e.g. between the measuring mechanism and the converter chamber, according to one embodiment of the differential pressure sensor. The dynamic brakes are flow resistances, in particular sintered metal inserts. The dynamic brakes can also be designed in such a way that they also assume the task of explosion protection.

In addition, it is proposed that filling bores are provided in the converter chamber, preferably as an extension of the auxiliary capillaries, which are used to fill the components that hydraulically communicate with one another with a hydraulic transmission fluid. After filling, each filling hole is closed in a pressure-tight, gas-tight or at least liquid-tight manner via a closure element. For example the locking element is a ball that is pressed into the bore and then caulked. It is also possible to weld the closure element in the bore. The closure elements are preferably arranged as close as possible to the differential pressure measuring cell. This has the advantage that the filling quantity of transmission fluid in the hydraulic system is reduced. If the closure element is located further outwards, the required amount of transmission liquid can be reduced by introducing filling elements, eg filling rods, into the filling bores.

In addition, it is provided that the connecting capillaries are designed in such a way that they electrically insulate the converter chamber from the measuring mechanism. The electrical insulation of the converter chamber from the measuring mechanism is preferably carried out via additional elements. These can be arranged in the connecting capillaries in the measuring mechanism and/or in the intermediate area and/or in the converter chamber, in particular in the transition from the connecting capillaries to the converter chamber. An additional insulating element can be, in particular, a ceramic insulating body or an insulating glazing. The connection must be gas-tight, either as a soldered connection or as a glazing. As stated, the electrical insulators can be provided in the converter chamber and/or in the measuring mechanism and/or between the measuring mechanism and the converter chamber. In particular, the electrical insulators can also be integrated as intermediate pieces in the connecting capillaries designed as capillary tubes.

• - Guarding für besseres EMV (elektromagnetisches Verhalten);
• - Geringerer bzw. kein Fremdspannungseinfluss;
• - Möglichkeit einen kapazitiven Siliziumchip einzusetzen, bei dem das Guarding eine Voraussetzung ist, dass nur geringere Störkapazitäten auftreten;
• - Das bislang erforderliche isolierende Element z.B. ein Keramiksockel, ein Glassockel oder eine ausreichend isolierende Klebung in der Wandlerkammer kann entfallen; Bei einer bevorzugten Ausgestaltung des erfindungsgemäßen Differenzdrucksensor wird das drucksensitive Element, üblicherweise ein Silizium-Chip, bevorzugt auf einen Silizium-Sockel aufgebracht. Nimmt man einen Silizium-Sockel anstelle des sonst üblichen Glassockels, so lässt sich ein günstigeres thermisches Verhalten (T-Hysterese) und ein geringerer statischer Druckfehler erreichen. Erklärung: Der E-Modul von Glas ist verschieden von dem E-Modul von Silizium. Bei Glas tritt eine größere Verformung und somit ein größerer Fehler infolge eines statischen Drucks auf als bei Silizium. Da Silizium jedoch kein Isolator ist, sondern eine gewisse Leitfähigkeit aufweist, sind für den sicheren elektrischen Betrieb Mindestisolationsstrecken erforderlich. Diese können z.B. durch in die Verbindungsleitungen eingesetzte keramische Isolierkörper und/oder entsprechend ausgestaltete Dynamikbremsen realisiert werden.
• - Der volle oder partielle Ex-Schutzverguss in der Wandlerkammer, der bislang bei Differenzdrucksensoren erforderlich war, kann entfallen. Bislang wurde der Verguss genutzt, um die Mindestabstände der stromführenden Elemente zum Massepotential möglichst gering halten zu können. Diese Abstandsreduzierung kann bei der Ausgestaltung der Erfindung entfallen, wo die Isolationselemente in den Verbindungskapillaren angeordnet sind. Zwecks Erzielung einer sicheren elektrischen Isolierung können die erforderlichen Mindestabstände um einiges kleiner ausfallen als beiden bislang bekannt gewordenen Lösungen. Auch lassen sich diese Mindestabstände ohne großen Aufwand erreichen.

This makes it possible to separate earth and ground (circuit zero point; Ue = reference point of the electrical supply = ground) and to achieve the following advantages for the current feedthrough:

• - Guarding for better EMC (electromagnetic behavior);
• - Lower or no external voltage influence;
• - Possibility to use a capacitive silicon chip, in which the guarding is a prerequisite that only low interference capacitances occur;
• - The previously required isolating element, for example a ceramic base, a glass base or a sufficiently insulating bond in the converter chamber, can be omitted; In a preferred embodiment of the differential pressure sensor according to the invention, the pressure-sensitive element, usually a silicon chip, is preferably applied to a silicon base. If a silicon base is used instead of the usual glass base, a more favorable thermal behavior (T hysteresis) and a lower static pressure error can be achieved. Explanation: The modulus of elasticity of glass is different from the modulus of elasticity of silicon. Glass suffers from greater deformation and thus greater error due to static pressure than silicon. However, since silicon is not an insulator but has a certain conductivity, minimum insulation distances are required for safe electrical operation. These can be implemented, for example, by using ceramic insulating bodies in the connecting lines and/or correspondingly designed dynamic brakes.
• - The full or partial explosion protection potting in the converter chamber, which was previously required for differential pressure sensors, can be omitted. So far, encapsulation has been used in order to be able to keep the minimum distances between the current-carrying elements and the ground potential as small as possible. This reduction in distance can be omitted in the embodiment of the invention where the insulation elements are arranged in the connecting capillaries. In order to achieve reliable electrical insulation, the required minimum distances can turn out to be somewhat smaller than in the two solutions that have been known hitherto. These minimum distances can also be achieved without great effort.

Furthermore, it is provided that the electrical connecting pins or connecting lines from the electrical converter are routed in a gas-tight manner through one of the end regions of the converter chamber facing away from the process in the direction of an electronic circuit board. This is preferably done via glass bushings. Because the transducer chamber is electrically isolated from the movement, the glass feedthrough PINs can be smaller and therefore have a higher throughput. The aim is in particular to achieve a pressure resistance that is greater than 1280 bar. Smaller PINs/encapsulation elements also allow more PINs to be accommodated in the same space. This may also mean that less oil volume is required.

In order to increase the measurement accuracy, the converter chamber is designed in such a way that the same transmission liquid or oil volumes are present on the low-pressure side (-) and the high-pressure side (+). The oil volumes on the high-pressure and low-pressure side can be equalized, for example, by creating a corresponding additional volume by enlarging or lengthening one of the bores.

In order to record and subsequently compensate for the influence of the static pressure on the measured values of the differential pressure sensor, a corresponding pressure-sensitive element for measuring the static pressure is provided in the converter chamber. In order to keep the oil volume as small as possible, the pressure-sensitive element for measuring the differential pressure and the pressure-sensitive element for measuring the static pressure are stacked one on top of the other. This is where the advantage of the previously mentioned reduction in the glazing of the PINs comes into play: Since these are smaller, the four additional PINs, which provide the measured values of the static pressure element, can be accommodated in the converter chamber without enlarging them would have to. The arrangement of the PINs is dealt with in more detail below in the description of the figures. However, it is also possible to arrange the pressure-sensitive element for measuring the differential pressure and the pressure-sensitive element for measuring the static pressure next to one another.

• 1: eine Darstellung, die den Aufbau eines erfindungsgemäßen Differenzdruckaufnehmers schematisch skizziert,
• 2a: eine Skizze des Verlaufs der Verbindungs- und Hilfsverbindungskapillaren bei einer Ausgestaltung des erfindungsgemäßen Differenzdrucksaufnehmers,
• 2b: die in 2a gezeigte Ausgestaltung im Überdruck- bzw. Überlastfall,
• 2c: eine weitere Darstellung der in 2b gezeigten Ausführungsform des erfindungsgemäßen Differenzdruckmessaufnehmers,
• 2d: eine realistischere Darstellung der Auslenkung der Membranen im Fall eines einseitig auftretenden Überdrucks,
• 3: eine perspektivische Ansicht einer Ausgestaltung des erfindungsgemäßen Differenzdruckmessaufnehmers,
• 3a: einen Längsschnitt im Bereich der beiden vorderen Hilfskapillaren,
• 3b: einen Längsschnitt im Bereich der beiden Verbindungskapillaren,
• 3b: einen Längsschnitt im Bereich der beiden hinteren Hilfskapillaren,
• 4: eine perspektivische Darstellung der Stromdurchführung mit Explosionsdarstellung der Wandlerkammer,
• 5: unterschiedliche Darstellungen vorteilhafter Varianten, wie die elektrische Isolierung zwischen Messwerk und Wandlerkammer erreicht wird,
• 6: unterschiedliche Ansichten und Schnitte durch eine Wandlerkammer mit einer Einheit zur Kompensation des statischen Drucks,
• 7: die Schaltung der elektrischen Anschlüsse von Differenzdruckmesszelle und statischer Druckmesszelle, und
• 8: einen Längsschnitt durch einen schematisch dargestellten Differenzdruckmesssaufnehmer, und
• 9: eine Draufsicht auf einen Füllkörper, bei dem die Druckmesszelle und die Druckmesszelle für den statischen Druck in einer Ebene angeordnet sind.

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

• 1 : an illustration that schematically outlines the structure of a differential pressure sensor according to the invention,
• 2a : a sketch of the course of the connection and auxiliary connection capillaries in an embodiment of the differential pressure sensor according to the invention,
• 2 B : in the 2a configuration shown in the case of overpressure or overload,
• 2c : another representation of the in 2 B shown embodiment of the differential pressure sensor according to the invention,
• 2d : a more realistic representation of the deflection of the membranes in the case of a one-sided overpressure,
• 3 : a perspective view of an embodiment of the differential pressure sensor according to the invention,
• 3a : a longitudinal section in the area of the two anterior auxiliary capillaries,
• 3b : a longitudinal section in the area of the two connecting capillaries,
• 3b : a longitudinal section in the area of the two rear auxiliary capillaries,
• 4 : a perspective view of the power feedthrough with an exploded view of the converter chamber,
• 5 : different representations of advantageous variants of how the electrical insulation between the measuring mechanism and the converter chamber is achieved,
• 6 : different views and sections through a converter chamber with a static pressure compensation unit,
• 7 : the wiring of the electrical connections of the differential pressure measuring cell and the static pressure measuring cell, and
• 8th : a longitudinal section through a differential pressure measuring sensor shown schematically, and
• 9 : a plan view of a packing in which the pressure measuring cell and the pressure measuring cell for the static pressure are arranged in one plane.

In 1 the structure of a differential pressure sensor 1 according to the invention is outlined. The differential pressure sensor 1 consists of a measuring unit 2 with a coplanar double membrane system 4a, 4b and a converter chamber 3. The converter chamber 3 is arranged in the housing adapter 22, the measuring unit 2 is integrated into the process connection 21. Housing adapter 22 and process connection 21 are connected to one another via a joint 20 in a pressure-tight and gas-tight manner, but at least in a liquid-tight manner.

The differential pressure measuring cell 12 with a pressure-sensitive element 13, usually a silicon chip, is arranged in the converter chamber. The differential pressure measuring cell 12 converts the pressures p1, p2 hydraulically transmitted by the process diaphragms or the separating diaphragms 5a, 5b into an electrical differential pressure signal and generates a corresponding measured value. Measuring mechanism 2 and converter chamber 3 are separated from one another by an intermediate area 19 . If necessary, an intermediate module 19 can be arranged in the intermediate area. However, this is not required. In the intermediate region 19, the connecting capillaries 10a, 10b and the auxiliary capillaries 11a, 11b, 11c, 11d run essentially parallel to one another and to the longitudinal axis of the differential pressure sensor 1. The capillaries can be designed as capillary bores and/or capillary tubes. The hydraulic couplings/crossings of the auxiliary capillaries 11a, 11b, 11c, 11d, which serve to protect against overpressure, are implemented in the converter chamber 3. Connection capillaries and auxiliary capillaries are in 1 only sketchily indicated and therefore not provided with reference symbols.

The figures 2a , 2 B and 2c show sketches of the course of the connecting capillaries 10a, 10b and the auxiliary capillaries 11a, 11b, 11c, 11d in an embodiment of the differential pressure sensor 1 according to the invention for determining the differential pressure of two pressures p1, p2. On or in an end area of the measuring unit 2 facing the process is a coplanar double membrane system tem provided with two double membranes 4a, 4b. The differential pressure measuring cell 12 with the pressure-sensitive element 13 is located in the converter chamber 3.

Each of the two double diaphragms 4a, 4b is composed of a separating diaphragm 5a, 5b and an overload diaphragm 6a, 6b arranged behind the separating diaphragm 5a, 5b in the direction of the usual pressure effect. A first pressure chamber 7a is formed between the first separating membrane 5a and the first overload membrane 6a, and a first additional pressure chamber 8a is formed between the first overload membrane 6a and the base body 9. A second pressure chamber 7b is formed between the second separating membrane 5b and the second overload membrane 6b, and a second additional pressure chamber 8b is formed between the second overload membrane 6b and the base body 9. The overload membranes 6a, 6b are preferably prestressed in such a way that they lie against the base body 9 of whatever shape during normal measurement operation and only lift off from the base body 9 when a predetermined critical limit pressure is exceeded. If the critical limit pressure is exceeded, there is a risk that the membrane of the pressure-sensitive element 13 will be destroyed and the differential pressure sensor 1 will become inoperable.

The first additional pressure chamber 8a is assigned a first connecting capillary 10a and the second additional pressure chamber 8b is assigned a second connecting capillary 10b. The pressure is transmitted hydraulically to the differential pressure cell 12 in the converter chamber 3 via the two connecting capillaries 10a, 10b. To protect the pressure-sensitive element 13 from overpressure on one side, a first auxiliary capillary 11a is assigned to the first additional pressure chamber 8a and a second auxiliary capillary 11b to the second additional pressure chamber 8b. A third auxiliary capillary 11c is associated with the first pressure chamber 7a and a fourth auxiliary capillary 11d is associated with the second pressure chamber 7b. For hydraulic coupling, the first auxiliary capillary 11a is connected to the fourth auxiliary capillary 11d and the second auxiliary capillary 11b is connected to the third auxiliary capillary 11c, with the connection points or crossings being arranged in the converter chamber 3 according to the invention.

In normal measurement operation, the pressure p1 is transmitted to the minus side of the pressure-sensitive element 13 via the separating membrane 5a, the auxiliary capillary 11c, the auxiliary capillary 11b and the connecting capillary 10b. The pressure p2 is transmitted to the plus side of the pressure-sensitive element 13 via the separating membrane 5b, the auxiliary capillary 11d, the auxiliary capillary 11a and the connecting capillary 10a. If the overload membranes 6a, 6b are positively or non-positively and substantially in full contact with the base body 9 of the measuring mechanism 2, a hydraulic channel may be introduced in the contact surfaces of the overload membranes 6a, 6b or in the two membrane beds.

In 2 B is shown by arrows how the overpressure PeÜL is transmitted in the capillary system in the event of an overload or an overpressure. In the case shown, an overpressure PeÜL occurs on the high-pressure side at the separating membrane 5b. If a one-sided overpressure PeÜL occurs on one of the membranes of the pressure-sensitive element 13, there would be a risk that the pressure-sensitive element 13, which is usually a silicon chip, would be destroyed. According to the invention, this danger is averted in that the overpressure protection is activated before the overpressure PeÜL reaches the pressure-sensitive element 13 .

In 2c shows more realistically how the overpressure protection works. Even better is the mode of action in the 2d apparent. The overpressure PeÜL applied to the separating diaphragm 5b is transmitted from the pressure chamber 7b via the additional diaphragm 6b to the additional pressure chamber 8b and finally brings the separating diaphragm 5b to rest on the overload diaphragm 6b already attached to the base body 9 of the measuring unit 2. Any transmission fluid still present in the additional pressure chamber 8b is pressed out. Subsequently, no more transfer liquid 16 can then be displaced; the one-sided overpressure PeÜL is not transferred to the minus side (-) of the pressure-sensitive element 13 . Furthermore, the excess pressure PeÜL is conducted in the bypass via the separating membrane 5b, the pressure chamber 7b, the auxiliary capillary 11d and the auxiliary capillary 11a to the additional pressure chamber 8a and from there to the overload membrane 6a. The prestressed overload membrane 6a is lifted from its bed in the base body 9 and transmits the excess pressure PeÜL to the pressure chamber 7a and the separating membrane 5a. As a result of the deflection of the overload diaphragm 6a and the separating diaphragm 5a, the hydraulic transmission fluid 16 pressed out of the high-pressure side can be accommodated in the pressure chamber 7a and the additional pressure chamber 8a.

According to the invention, so much transfer liquid 16 is transferred from the high-pressure side of the double-diaphragm system 4b to the low-pressure side of the double-diaphragm system 4a until no more transfer liquid 16 can be displaced on the high-pressure side, since the separating diaphragm 5b rests on the overload diaphragm 6b supported on the base body of the measuring unit 2. The maximum pressure, which is present on the plus side (+) of the pressure-sensitive element 15, can be determined via the restoring force of the overload membrane 6a, 6b (spring in the deflected state) or dimension. This effectively counteracts the destruction of the pressure-sensitive element 13, usually a silicon chip.

In order to ensure that the excess pressure PeÜL first deflects the overload membrane 6a before it reaches the membrane of the pressure-sensitive element 13, the hydraulic paths are routed in series in the solution according to the invention. The pressure-sensitive chip 13 is located at the end of the series circuit. This is supported or ensured by appropriately adapted capillary geometries, which fulfill a braking function in the direction of the pressure-sensitive chip. In addition or as an alternative, dynamic brakes 18 can also be provided upstream of the pressure-sensitive element 13 . In particular, the connecting capillaries 10a, 10b and the auxiliary capillaries 11a, 11b, 11c, 11d are suitably dimensioned in terms of length and diameter, so that the function of overload protection can take effect reliably.

According to a further development of the differential pressure measuring sensor 1 according to the invention, it is considered advantageous if so-called dynamic brakes 18 are additionally or alternatively used in the connecting capillaries 10a, 10b. These delay the transmission of the pressure, in particular an overpressure PeÜL, and protect the pressure-sensitive element 13 in particular from pressure peaks occurring in the process. The dynamic brakes 18 can be sintered metal inserts. When using the differential pressure sensor 1 in the explosion-proof area, the dynamic brakes are made of a non-conductive material. In this case, the dynamic brakes 18 then fulfill a dual function: delayed transmission of the pressure and explosion protection according to a required type of explosion protection.

3 shows a perspective view of an embodiment of the differential pressure sensor according to the invention. In 3a a longitudinal section in the area of the two front auxiliary capillaries can be seen. The figures 3b and 3c show longitudinal sections in the area of the two connecting capillaries or in the area of the two rear auxiliary capillaries.

4 shows a schematic representation of the converter chamber 3 with the two connecting capillaries 10a, 10b and the four auxiliary capillaries 11a, 11b, 11c, 11d. During normal measurement operation, the pressures p1, p2 present at the separating membranes 5a, 5b are transmitted hydraulically to the pressure-sensitive element 15 via the connecting capillaries 10a, 10b. The pressure p1 is on the plus side (+), the pressure p2 on the minus side (-) of the pressure-sensitive element 13. In this configuration, six vertical capillary bores (that is, parallel to the longitudinal axis of the differential pressure sensor 1 ) and two horizontal capillary bores are required in the converter chamber 3 . It may also make sense to have two filling and closure accesses to make filling easier. It should be noted that the dynamic brakes 18 make filling more difficult or can lengthen the filling times.

4 shows a perspective view of the power feedthrough 23 and an exploded view of a cube-shaped embodiment of the differential pressure measuring cell 12. An insulating base (eg a ceramic base) 31 is connected to the bottom surface of a recess in the converter chamber 3 via a suitable adhesive 30. The pressure measuring cell 12 , which preferably has a silicon chip as the pressure-sensitive element 13 , is connected to the ceramic base 31 by means of an adhesive 32 . For the purpose of minimizing the required volume of oil or the volume of the transmission liquid 21, a filling body 33 is provided, which encloses the pressure measuring cell 12 as closely as possible in the side area. The filling body 33 is closed with a cover 34 . The converter chamber 3 is closed to the outside with a sealing cap 34 for the current feedthrough 23 . The silicon chip 13 is insulated via the insulation base 31 (for example a ceramic base or glass base), which has a thickness d≧0.5 mm, for example for reasons of explosion protection. Furthermore, the insulation of the silicon chip 13 and its bonding connections 24 is provided by the filling body 33 with cover 34, which is made of a suitable plastic, for example. The connecting capillaries 10a, 10b, designed as capillary tubes, and the auxiliary capillaries 11a, 11b, 11c, 11d are shown below.

5 shows different representations of advantageous variants of how the electrical insulation between the measuring mechanism 2 and the converter chamber 3 can be implemented via insulation elements 25, preferably insulation tubes 25, adapted in or on the capillary tubes 17. Incidentally, in these configurations, the ceramic base 31 glued in place in the converter chamber 3, as described above, can be dispensed with. The electrical insulation between measuring mechanism 2 and converter chamber 3 takes place in the area of the capillary tubes between the corresponding connecting capillaries 10a, 10b or at the transition of the capillary tubes to measuring mechanism 2 or to converter chamber 3.

As in the illustration on the left 5 can be seen, the electrically insulating ceramic tubes 25 in the converter chamber 3 ( 5a) , in the intermediate area between converter chamber 3 and measuring unit 2 ( 5c ) or in measuring element 2 ( 5b) be executed. The insulation preferably achieves potential isolation from ground or the internal ground. This is required for Ex ia safety level and electrical safety. The alternative that the Ex separation can also be achieved by appropriate design of the dynamic brakes 18 has already been mentioned above. The differential pressure measuring sensor 1 according to the invention can also be used in potentially explosive areas. To do this, it must meet the ex d safety requirements, for which additional safety measures are required.

6 shows a converter chamber 3 or its components and different sections through the converter chamber 3 or its components. In this embodiment, a measuring cell 27 is also provided for determining the static pressure. In 6a shows the power bushing 23 with an advantageous arrangement of the connection pins 26 for the differential pressure measuring cell 14 with the pressure-sensitive element 15 and the measuring cell 27 arranged above it for determining the static pressure. The PINs 26 are preferably found symmetrically in the edge area of the two pressure measuring cells 14, 27, which are preferably arranged stacked one on top of the other. However, it can also be an advantage to position at least one PIN asymmetrically in order to make subsequent processing, for example soldering on the circuit board, safer later in the process (poka-yoke principle). Either the PINs 26 all end in one plane or in parallel planes. Two pins 1.1, 1.2 of the eight pins 26 ( 7c ) can be used without insulation, e.g. B. soldered, since they are on ground / housing potential.

PINS 2 and 3 could be electrically connected together, i.e. in a common PIN, to potential ( 7b) . The electrical insulation then preferably takes place via a glazing. If the ground PINS 1.1, 1.2, which correspond to PINS 1, 8, and PINS 2, 3 for the power supply are combined, the two bridges are connected in parallel to the power supply. This circuit is shown in 7c .

In order to meet the requirements of electrical safety and for use in hazardous areas, all PINs 26 are arranged or spaced such that there is sufficient dielectric strength both from PIN 26 to PIN 26 and from PIN 26 to the housing/ground of the converter chamber 3 is. Since the oil volume is all the smaller, the smaller the interior space of the converter chamber 3 is dimensioned, the interior space preferably has a diameter of <10 mm, in particular <8 mm.

6b shows a longitudinal section through the stacked pressure measuring cells 12, 27. In particular, the pressure measuring cell 27 is an absolute pressure measuring cell. The PINS 26 are routed through the electrical feedthrough 30 so that they are isolated from one another. The power feedthrough 23 is designed to be pressure-resistant and gas- or liquid-resistant. The PINs 26 are either soldered or glazed. Alternatively they are pressed in or impulse welded. Only the ground PINS are arranged in the housing without insulation, all others must be insulated. This is possible if the housing is isolated and connected to the measuring unit via the capillaries. Otherwise, all PINs (including the ground PINS) must be electrically isolated.

In order to minimize the oil volume required, the differential pressure measuring cell 12 with the bonding wires 24 is embedded as closely as possible in the filling body 33 and the filling body cap 37 . The packing cap 37 has a recess for receiving the chip/static pressure cell 27 . The sealing cap 35 follows an insulating film 29. 6c shows a cross section in the area of the differential pressure measuring cell 12, while 6d shows a section in the area of the chip 27 for measuring the static pressure.

In the figures 7a , 7b and 7c the circuits for the previously mentioned arrangements of the PINs 26 are shown. The differential pressure (1.2) and the static pressure (1.1) are measured via two resistance bridges. The measured values are sent to an electronic circuit board 36 for further processing. 7a shows the basic connection diagram of the two Si chips 15, 27. In order to be able to operate the circuit completely independently, eight PINs 26 are required; minimum are six PINs 26 ( 7b) necessary. 7c shows a circuit with 7 PINs 26. This interim solution has a separate plus supply, but a common ground. The advantage of using a smaller number of PINs 26 is clearly that space can be saved. The PINs 26 for the ground connection can also be implemented as a direct connection between the corresponding PIN 26 or the corresponding PINs 26 and the conductive housing (metal housing). The connection can be made by soldering, pressing in or welding.

• (2), (3): PINs 26 für den Anschluss der Versorgungsspannung,
• (4), (5): PINs 26 für das Brückenausgangssignal der statischen Druckmesszelle 27,
• (6), (7): PINs 26 für das Brückenausgangssignal der Differenzdruckmesszelle 14,
• 1 = (1.1): Versorgungsspannungs-Minusanschluss (Masse),
• 8 = (1.2): Versorgungsspannungs-Minusanschluss (Masse).

Below is the function of each in 7 shown PINs 26 listed:

• (2), (3): PINs 26 for connecting the supply voltage,
• (4), (5): PINs 26 for the bridge output signal of the static pressure measuring cell 27,
• (6), (7): PINs 26 for the bridge output signal of the differential pressure measuring cell 14,
• 1 = (1.1): supply voltage minus connection (ground),
• 8 = (1.2): supply voltage minus connection (ground).

As already described above, a common PIN 26 can also be used for the ground connection.

• ① Innenvolumen, das ev. mit einem Verguss ausgefüllt ist
• ② Schweißung zwischen Gehäuseadapter 22 und Messwerk 2
• ③ Druckzuführung Wandlerkammer 3 - Messwerk 2
• ④ Druckzuführung zur Wandlerkammer 3
• ⑤ Stromdurchführung 23 mit PIN/Einglasung
• ⑥ Ölverschluss 15
• ⑧ Trennung zwischen Gehäuse und Sensorrückraum
• ⑨ Exd-Gewinde Gehäuse-Sensor, z.B. über ein Second Containment und/oder einen Verguss
• ⑩ Verschlusskappe 35 Stromdurchführung 23 (GDF)

8th shows a longitudinal section through a differential pressure measuring sensor 1 shown schematically 8th lists the different zones AG to which the differential pressure sensor 1 is exposed. Since the zones are listed by name in the figure, they will not be repeated at this point. The encircled numbers schematically document components that characterize the basic structure of the differential pressure sensor 1 according to the invention:

• ① Inner volume that may have been filled with encapsulation
• ② Welding between housing adapter 22 and measuring unit 2
• ③ Pressure supply converter chamber 3 - measuring unit 2
• ④ Pressure supply to converter chamber 3
• ⑤ Power feedthrough 23 with PIN/glazing
• ⑥ Oil cap 15
• ⑧ Separation between the housing and the rear of the sensor
• ⑨ Exd thread housing sensor, eg via a second containment and/or encapsulation
• ⑩ Closing cap 35 power feedthrough 23 (GDF)

9 shows a plan view of a packing 33 in which the pressure measuring cell 12 and the pressure measuring cell 27 for the static pressure are arranged in one plane. The distances between the pins - can be seen in the 9 only the recesses 38 for the pins from the power feedthrough - are chosen so that a galvanic isolation is ensured.

Reference List

1

differential pressure sensor

2

measuring mechanism

3

converter chamber

4

double membrane system

4a, 4b

first double diaphragm, second double diaphragm

5a, 5b

first separating diaphragm, second separating diaphragm

6a, 6b

first overload diaphragm, second overload diaphragm

7a, 7b

first pressure chamber, second pressure chamber

8a, 8b

first additional pressure chamber, second additional pressure chamber

9

body

10a, 10b

first connection capillary, second connection capillary

11a, 11b

first auxiliary capillary, second auxiliary capillary,

11c, 11d

third auxiliary capillary, fourth auxiliary capillary,

12

differential pressure measuring cell

13

pressure-sensitive differential pressure element

14a, 14b

filling hole

15a, 15b

closure element

16

Transmission Fluid / Hydraulic Fluid / Oil

17

capillary tubes

18

dynamic brake

19

Intermediate area / intermediate module

20

coincidence

21

process connection

22

housing adapter

23

current feedthrough

24

bond connection

25

isolation tube

26

pin code

27

Measuring cell for determining the static pressure

28

Packing cap with recess

29

Insulation film / PTFE film

30

Adhesive for gluing the insulation base (ceramic base)

31

ceramic base

32

Adhesive for gluing the pressure measuring cell

33

random packing

34

packing cover

35

Closing cap for power feedthrough

36

electronics board

37

fill cap

38

Recess for pin

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was 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.

Patent Literature Cited

• DE 3222620 A1 [0004]
• WO 2018/165122 A1 [0006]
• US 10656039 B2 [0017]

Claims (19)

Differential pressure sensor (1) for determining the differential pressure of two pressures (p1, p2) with a measuring unit (2) and a converter chamber (3), with a coplanar double membrane system (4) on or in an end area of the measuring unit (2) facing the process two double membranes (4a, 4b) are provided and a differential pressure measuring cell (12) with a pressure-sensitive element (13) is arranged in the converter chamber (3), the two double membranes (4a, 4b) each consisting of a separating membrane (5a, 5b) and an overload membrane (6a, 6b) arranged behind the separating membrane (5a, 5b) in the direction of the pressure effect, with a first pressure chamber (7a) between the first separating membrane (5a) and the first overload membrane (6a) and between the first overload membrane ( 6a) and the base body (9) a first additional pressure chamber (8a) is formed, wherein between the second separating membrane (5b) and the second overload membrane (6b) a second pressure chamber (7b) and between the z wide overload membrane (6b) and the base body (9) a second additional pressure chamber (8b) is formed, wherein the first additional pressure chamber (8a) is assigned a first connecting capillary (10a) and wherein the second additional pressure chamber (8b) is assigned a second connecting capillary (10b), wherein the two connecting capillaries (10a, 10b) transmit the pressure hydraulically to the converter chamber (3), and wherein - to protect the pressure-sensitive element (13) from overpressure on one side - the first additional pressure chamber (8a) has a first auxiliary capillary (11a) and the a second auxiliary capillary (11b) is assigned to the second additional pressure chamber (8b), with a third auxiliary capillary (11c) being assigned to the first pressure chamber (7a) and a fourth auxiliary capillary (11d) being assigned to the second pressure chamber (7b), wherein for the purpose of hydraulic coupling the first auxiliary capillary (11a) is connected to the fourth auxiliary capillary (11d) and the second auxiliary capillary (11b) is connected to the third auxiliary capillary (11c), the Ve Connection points / crossings are each arranged in the converter chamber (3). differential pressure sensor claim 1 , wherein the overload membranes (6a, 6b) are prestressed in such a way that they rest against the base body (9) and only lift off from the base body (9) when a predetermined critical limit pressure is exceeded. differential pressure sensor claim 1 or 2 , wherein the connecting capillaries (10a, 10b) and the auxiliary capillaries (11a, 11b, 11c, 11d) run essentially parallel to the longitudinal axis (L) of the differential pressure sensor (1), starting from the measuring mechanism, and wherein the auxiliary capillaries (11a, 11b, 11c , 11d) in the converter chamber (3) show a change of direction, so that the connection points/intersections are in the converter chamber (3). Differential pressure sensor according to one or more of the preceding claims, wherein a block of material is arranged in the intermediate region (19) of the measuring mechanism (2) and converter chamber (3), and wherein the capillaries (10a, 10b, 11a, 11b) arranged in the block of material are 11c, 11d) are capillary bores or capillary tubes (18). Differential pressure sensor according to one or more of the preceding claims, wherein the connecting capillaries (10a, 10b) and/or the auxiliary capillaries (11a, 11b, 11c, 11d) arranged in the measuring unit (2) and in the converter chamber (3) are capillary bores . Differential pressure sensor according to one or more of the preceding claims, wherein the converter chamber (3) has two connecting capillaries (10a, 10b) and four auxiliary capillaries (11a, 11b, 11c, 11d) at its end region facing the process, which are preferably arranged parallel to one another and which are essentially congruent with the connecting capillaries (10a, 10b) and auxiliary capillaries (11a, 11b, 11c, 11d) designed as capillary bores or capillary tubes (17) in the material block and/or in the measuring mechanism (2). Differential pressure sensor according to one or more of Claims 1 until 6 , wherein the connecting capillaries (10a, 10b) and/or the auxiliary capillaries (11a, 11b, 11c, 11d) are designed and/or dimensioned in such a way that a one-sided overpressure (peÜL) above the predetermined critical limit pressure is limited by means of the overpressure protection, before the excess pressure is transmitted to the pressure-sensitive element (13) of the differential pressure measuring cell (12). Differential pressure sensor according to one or more of the preceding claims, wherein at least one pressure brake (18) is built into each of the connecting capillaries (10a, 10b), which serves to dampen pressure surges. Differential pressure sensor according to one or more of the preceding claims, in which filling bores (14a, 14b) are provided in the converter chamber, preferably as an extension of the auxiliary capillaries (11a, 11b), which are used to fill the components hydraulically communicating with one another with a hydraulic transmission fluid (16) to fill, each filling hole (14a, 14b) after filling over a closure element (15a, 15b) is closed pressure-tight, gas-tight or at least liquid-tight. Differential pressure sensor according to one or more of the preceding claims, wherein electrical connection pins (26) are guided in a gas-tight manner through one of the end regions of the converter chamber (3) facing away from the process in the direction of an electronic circuit board (36). Differential pressure sensor according to one or more of the preceding claims, wherein the connecting capillaries (10a, 10b) and auxiliary capillaries (11a, 11b, 11c, 11d) are designed in such a way that they electrically insulate the converter chamber (3) from the measuring unit (2). Differential pressure sensor according to one or more of the preceding claims, wherein electrical insulators (25) are provided in the converter chamber (3) and/or in the measuring mechanism (2) and/or in the intermediate space (14) between the measuring mechanism (2) and the converter chamber (3). differential pressure sensor claim 12 wherein the electrical insulators (25) are provided in the connecting capillaries (10a, 10b) and the auxiliary capillaries (11a, 11b, 11c, 11d). differential pressure sensor Claim 13 or any of the preceding Claims 1 - 13 , wherein the connecting capillaries (10a, 10b) and the auxiliary capillaries (11a, 11b, 11c, 11d) are provided at least in sections with an electrical insulator (25), in particular a ceramic insulating body or an insulating glazing, and/or wherein the connecting capillaries (10a , 10b) and the auxiliary capillaries (11a, 11b, 11c, 11d) are attached via a gas-tight connection in the corresponding capillaries of the measuring unit (2) and/or the converter chamber (3) or the capillary tubes (17). Differential pressure sensor according to one or more of the preceding claims, wherein the electrical insulators (25) are integrated as spacers in the connecting capillaries (10a, 10b) and auxiliary capillaries (11a, 11b, 11c, 11d) designed as capillary tubes (17). Differential pressure sensor according to one or more of the preceding claims, wherein the pressure-sensitive element (13) is a silicon chip, and wherein the differential pressure (p2-p1) is determined using a capacitive or resistive measuring method or resonator. Differential pressure sensor according to one or more of the preceding claims, wherein the converter chamber (3) is designed in such a way that the same transmission liquid volumes are present on the low-pressure side (-) and the high-pressure side (+). Differential pressure sensor according to one or more of the preceding claims, wherein a pressure-sensitive element (27) for measuring the static pressure is provided in the converter chamber (3). Differential pressure sensor according to one or more of the preceding claims, wherein the pressure-sensitive element (13) for measuring the differential pressure (dp) and the pressure-sensitive element (27) for measuring the static pressure (pstat) are stacked on top of one another or arranged next to one another in the converter chamber (3). .

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