DE102008000439A1 - Pressure transducer with a membrane - Google Patents

Abstract

The present invention relates to a pressure transducer with a membrane (1). On the membrane (1), at least one sensor (2) for detecting deformations occurring by pressurizing the membrane (1) is attached. Furthermore, the membrane (1) has at least one reinforcing area (11, 13) in which a recess (21) penetrating the contour of the reinforcing area (11, 13) is formed, in which the sensor (2) is at least partially accommodated.

Description

The The present invention relates to a pressure transducer having a A membrane according to claim 1, on which a sensor is attached to a particular one Place is arranged.

Especially be pressure transducers (pressure sensors or pressure transducers) in the food and Semi-luxury food industry, the pharmaceutical industry and biotechnology and genetic engineering for pressure measurement by detection of the pressurization the membrane occurring deformations used, the pressure transducer manage without a separate diaphragm seal or without filling medium. Such Pressure transducers are also referred to as "dry measuring cells".

Usually are sensors (eg strain sensors) for such dry measuring cells on the side facing away from the pressure to be measured a flat membrane arranged, with a high measurement signal by stress concentrations at bending edges (Transition from thin membrane regions to reinforcement regions) the membrane is produced, but where the sensors are not directly attached can be.

Such a pressure sensor with a sensor element of a ceramic substrate and with strain-sensitive resistors is in DE 203 08 382 U1 disclosed. This sensor element consists of three different annular thickness ranges, ie from a central thickness range, a thin average thickness range and an edge thickness range. Furthermore, at least four of the strain-sensitive resistors are arranged on the side of the sensor element which faces away from the pressure to be measured, wherein the resistances are respectively arranged on the outer edge and inner edge of the thin annular middle thickness region. These resistors are attached to the side facing away from the pressure to be measured at locations on the stepped diaphragm formed on which even large mechanical stresses occur when pressurized. Thus, the resistors are stressed there particularly strong mechanical.

Furthermore, the shows DE 101 53 424 A another pressure sensor. This pressure sensor comprises a cross-hat-shaped carrier substrate, which is formed from a reinforced carrier ring and a membrane integrally formed thereon. On the membrane strain gauges are applied in thin film technology. These strain gauges are arranged on the membrane at its outer edge region radially inwardly disposed at the side facing away from the pressure to be measured.

By the radial indentation of the strain gauges to the center the diaphragm of the pressure transducer can be temperature-induced Strains or stresses are reduced. By this construction the pressure transducer is a positioning of the strain gauges reached next to the bending edge, but the sensitivity the pressure measurement is significantly worsened, as these strain gauges positioned outside the range of maximum mechanical strain are.

It It is therefore an object of the present invention to provide a pressure transducer to provide, which has a membrane on which a sensor on a fixed in place so that high sensitivity given at the same time long durability of the sensor.

The Object of the present invention is with a pressure transducer with a membrane according to claim 1 solved.

advantageous Further developments are specified in the subclaims.

Has according to the invention the pressure transducer has a membrane that is at least one on the membrane attached sensor for detecting by pressurization the membrane has occurring deformations and at least one gain region. In the gain region, one is the contour of the gain region formed by opening recess in which the sensor at least partially recorded.

The Membrane has at least one reinforcement area and can arch in a direction of pressure change, so that the membrane and the recess in the reinforcement area attached sensor for detecting deformations (i.e., strains or upsets) of the membrane due to the gain region experience locally different deformations. Since the sensor for Detecting these deformations by means of the recess (that is, at least partly in this) directly at the transition to the reinforcement area the membrane is arranged, it is ensured at the same time a high sensitivity is given and on the other hand by the reinforced area excluded an overload can be.

The the contour of the amplification area by opening recess The membrane in which the sensor is to be located is in one place formed on the membrane, which is a particularly suitable location represents for the sensor gauge tap on the membrane, and at the same time the mechanical stability (eg the Resistance to detachment from the membrane, etc.) of the sensor is not affected.

Consequently is the recess (eg, a groove) at a bending edge (i.e., the transition) from the reinforcing area to a thinner one Membrane area) for direct attachment of the strain sensor in the Recess formed.

• – hohe Empfindlichkeit bei gleichzeitig hoher Lebensdauer des Druckwandlers, und
• – kein flüssiges Druckübertragungsmedium ist erforderlich.

Thus, the pressure transducer according to the invention has the following advantages:

• - High sensitivity with high durability of the pressure transducer, and
• - No liquid pressure transmission medium is required.

According to one preferred embodiment, the sensor is in the recess recorded so that the sensor on the sensor intended continuation of the contour of the gain range cuts. This ensures that the sensor is always at the transition between the reinforcement region and the adjacent thinner membrane region is arranged on the membrane.

Further the reinforcement region can be formed centrally on the membrane be. The sensor is preferably on the medialabgewendeten side of the Be arranged membrane which faces away from the pressure to be measured.

Prefers the pressure transducer has two gain ranges. One of Reinforcement areas are formed centrally on the membrane, and the other is formed in an edge area on the diaphragm. Preferably, the sensor is in the central gain area by means of the recess in the transition region described above arranged. Next, the gain area in the edge area the membrane as a clamping or receiving area of the membrane for serve the entire pressure transducer. Incidentally, the / can Reinforcement area / e integral with the thinner one Membrane area be formed.

Prefers the recess is at a point of great deformation arranged the membrane. Further, the recess may be a groove, at least partially in the reinforcement area the membrane extends.

Prefers this groove extends longitudinally, d. H. in a radial direction, through the entire gain range the membrane. Furthermore, several grooves that the Break the contour of the gain area, in the gain area be educated. These may be at the perimeter of the gain area at regular angular intervals from each other be arranged.

Further the membrane is preferably on the flat side by a medium (eg water, oil, air, gas, etc.) pressurized.

Prefers the amplification areas can be circular cylindrical be educated. The recess is then designed such that the sensor on a continuation of the circular cylinder circumference of the respective gain region is arranged. This is the sensor in the transition region of the amplification arranged to the thinner membrane region of the membrane.

Prefers the reinforcement region and the membrane region are cylindrical formed, wherein the base area of the membrane area and the base area of the reinforcing area concentric Circles with respect to the circle center of the base form the pressure transducer.

Of the Pressure transducer according to the invention consists in a preferred embodiment of a circular disc, which has three areas of different thickness in the radial direction. These areas are coaxial with each other and have in Direction perpendicular to the axis of the disc (the pressure transducer) different thickness or gain ranges. The central one Area and the edge area have a significantly larger Thickness as the middle area enclosed by them (thinner Membrane area). The groove is preferred in at least one of Reinforcement areas formed such that a strain-sensitive Sensor on a continuation of the circular cylinder circumference of the respective Amplification area is arranged.

at These pressure transducers according to the invention form when pressurizing the pressure transducer and thus when pressurized of the sensor mechanical stresses (deformations of the membrane), especially strong at the groove in the reinforcement area occur and measured by means of the strain-sensitive sensor can be.

These strain-sensitive sensors can be resistive strain sensors (RDS) (eg strain gauges), thin-film sensors (DFS) and piezoresistive sensors (PRS). The mentioned sensor groups all belong to the resistive strain sensors (RDS).

The strain gauges preferably detect strains through metallic meanders of approximately 1 μm, which in turn are attached by means of a carrier film at the location of the measurement, ie in the recess of the reinforcement region. The thin film sensors, which are arranged in the recess of the membrane in the form of an approximately 50 nm thick thin-film structure, are thus connected in quasi-integral manner to the membrane. The piezoresistive sensors are usually designed such that they have one or more semiconductor resistance elements (eg do siliconized crystals), which convert deformations (strains or compressions) into electrical signals.

Prefers the pressure transducer according to the invention has a sensor, which is constructed as a chip component, which consists of a geometric staggered arrangement of at least one semiconductor element, preferably four semiconductor elements, wherein these semiconductor elements turn by arrangement at an angle of 90 ° to each other electrical Resistance changes with different signs experienced and in a bridge circuit (preferably Wheatstone bridge) interconnected or electrically connected.

Preferably are each two resistors of the four semiconductor elements parallel and thus both resistance pairs at an angle of 90 ° to each other arranged that the resistor pairs resistance changes with different signs learn that the absolute difference the resistances is maximum and that these are in a bridge circuit, preferably Wheatstone bridge, are electrically connected.

Prefers the pressure transducer has a reinforced edge area, in which also recesses for sensors can be placed. Such sensors are with the corresponding sensor in the corresponding Recess in the central reinforcement area on the Membrane electrically connected and interconnected. Preferably, the Randbereich cylindrical in shape and a circular ring As a base, this annulus is preferred concentric with the base of the pressure transducer and the formed central amplification area.

Prefers the pressure transducer according to the invention has a membrane, which can be laminated with PTFE. Further, the membrane may be Au, Ag, PT and / or Ta be coated.

Prefers is the pressure transducer according to the present invention formed with a membrane, which as a part of a container wall in particular for the measurement of levels or Container pressures is provided.

below is the construction of the pressure transducer according to preferred Embodiments of the invention with reference to the attached Drawings explained and described in detail. In The drawings show the following:

1A FIG. 12 is a plan view of a pressure transducer according to a first embodiment of the invention having two gain regions, a membrane region and a sensor. FIG.

1B is a sectional view of the pressure transducer according to the first embodiment of the invention along the line AA in 1A ,

2 is a perspective view of a pressure transducer according to a second embodiment of the invention.

3A is a plan view of the pressure transducer according to the second embodiment of the invention.

3B is a sectional view of the pressure transducer according to the second embodiment of the invention along the line BB of 3A ,

In 1A and 1B is a pressure transducer with a membrane 1 according to a first embodiment of the present invention. The pressure transducer according to the invention is preferably used as a part of a container wall for measuring levels or container pressures z. B. in chemical engineering and sterile process engineering, the pharmaceutical industry and biotechnology and genetic engineering applied.

As in 1A and 1B is shown, the pressure transducer according to the first embodiment of a circular disc (the membrane 1 ), which has three regions of different thickness in the radial direction. The pressure transducer with the membrane 1 has a cylindrical shape. This cylindrical shape is made up of a central reinforcement area 11 , an edge reinforcement area 13 and a membrane annulus region located between these regions 15 educated. Thus, the gain range is 11 centrally on the membrane 1 trained, and the gain area 13 is radially outward as an edge region on the membrane 1 educated. In the first embodiment, both the central amplification area 11 as well as the edge reinforcement area 13 the same thickness or thickness. However, they can also have different thickness dimensions within the respective areas as well as one another. The areas 11 . 13 and 15 are also located coaxially with one another and have the different thicknesses in the direction perpendicular to the axis of the pressure transducer. As in 1a and 1B are shown, the two gain areas 11 and 13 integral with the membrane annulus area 15 educated.

The edge reinforcement area 13 can serve as a clamping and fastening area for the pressure transducer. Since a clamping arrangement z. B. is generally known as part of a container wall, this is not specifically shown and not described in the following description.

Next is in the first invention Embodiment in the central reinforcement area 11 a recess 21 educated. This recess 21 is formed such that it at least the outer contour of the central reinforcing region 11 breaks through.

In the first embodiment, the recess 21 of the pressure transducer z. B. formed by a semi-circular end mill, as in the plan view in 1A is shown. Further, there is a bottom portion of the recess 21 in the same plane as the membrane ring area 15 , Thus, the bottom portion of the recess 21 the same thickness as the membrane ring area 15 , The recess 21 Alternatively, it may be a slightly larger or smaller thickness dimension than the membrane ring portion 15 exhibit.

In the recess 21 and on the membrane ring area 15 is a sensor (eg a strain gauge) 2 for detecting by pressurizing the membrane 1 attached deformations attached. The sensor 2 is so in the recess 21 recorded that he is an imaginary continuation of the contour of the central amplification area 11 cuts. That is, because the central reinforcement area 11 is formed circular cylindrical, the position of the sensor arrangement intersects in the recess 21 and on the membrane ring area 15 an imaginary continuation of the circumference line of the central amplification area 11 ,

Thus, in the pressure transducer according to the first embodiment of the invention, the sensor 2 on the back of the flush-mounted membrane 1 directly at a transition area between the central reinforcement area 11 and the membrane ring area 15 attached. This transition region thus intersects a bending edge of the membrane caused by the thickness transition from the reinforcement region 11 to the thin membrane ring area 15 is formed, whereby a high measurement signal due to stress concentrations at the bending edge of the sensor 2 is delivered.

Because the sensor 2 partially within the recess 21 of the central amplification area 11 and partly on the membrane ring area 15 is arranged, it is thus ensured that, on the one hand, a sufficiently large measurement signal through the sensor 2 can be generated, and that on the other hand, the mechanical stress of the sensor is not excessive.

Furthermore, in 2 . 3A and 3B A second embodiment of the pressure transducer according to the invention described.

The second embodiment has in principle the same structure as the first embodiment. In particular, in the pressure transducer of the second embodiment, the recess 21 as one over the entire membrane 1 longitudinal groove 21 formed, whereby an additional, longitudinal bending edge on the membrane 1 is produced.

In this recess 21 is the sensor 2 arranged in a similar position as in the first embodiment. That is, the sensor 2 again is in the transition region between the gain region 11 and the membrane ring area 15 in the groove 21 arranged.

Also with the pressure transducer of the second embodiment can the same effects and effects as in the first embodiment be achieved.

Further can also do more than one the contour of the gain range breaking grooves in the respective reinforcement areas be formed of the membrane. These can be z. B. on the circumference of the gain region in preferably uniform Be arranged angular distances from each other.

Of Furthermore, several sensors can be in several recesses (Grooves) are arranged, which in a bridge circuit z. B. interconnected in a Wheatstone bridge or electrically are connected. The measurement results can be sent to a measuring device (not shown) are transmitted and evaluated by this and spent.

In the above embodiments is the Sensor partially at or within the central gain range attached to the membrane. Alternatively, the sensor or the sensors also in a transition region of the membrane area be arranged to the outer edge region. It is only relevant to the invention in this embodiment, that the sensor is arranged such that it is in a transition region from one of the two reinforcement regions to the membrane ring region arranged on a corresponding bending edge as described above is.

Furthermore, only one or more than two reinforcement regions can also be formed on the membrane. These reinforcement areas can have different strengths. Incidentally, strain sensors, thin-film sensors and / or piezoresistive sensors are usually used as sensors. These sensors can each be arranged separately or jointly on chip components, which in turn are preferably arranged in pairs at an angle of 90 ° to one another, and the resistance changes with different signs experienced and in a bridge circuit (preferably Wheatstone bridge) interconnected or electrically connected.

Of the Pressure transducer according to the invention with the different Reinforcement areas for measuring levels or container pressure can also be used in food and stimulant technology, in chemical engineering and Sterile process technology or in the automotive technology z. B. in the Cylinder pressure measurement of engines, oil and brake pressure measurements, etc. are applied.

The Membrane is usually made of an elastic material z. As stainless steel, brass, Hastelloy alloys or other common Membrane materials produced. The requirement for the membrane is such that it can deform under pressure, and that she returns to her original form. Incidentally, it should have a suitable bending curve, which in particular by the reinforcement regions arranged on the membrane and recesses is guaranteed.

Preferably is the central reinforcement area as protection against pressure overload provided in places on the membrane, that in case it is too high pressure the membrane on opposite housing sections can support and prevents their damage.

The The present invention further provides a particular advantage the sensitivity of the sensor, as this at the appropriate transition areas at least partially in the recesses of the reinforcement areas is arranged.

One Another advantage is that the membrane has a high mechanical Stability with excellent measuring tap having.

In the above preferred embodiments the pressure transducer formed as a disc and the gain ranges are formed circular cylindrical. Alternatively it is possible that the shape of the reinforcement areas also be a different shape than a circular cylinder-like design can. For example, you can use cylindrical shapes with oval, quadrangular or polygonal or slightly modified ground plan shapes exhibit.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 20308382 U1 [0004]
• - DE 10153424 A [0005]

Claims (19)

Pressure transducer with a membrane ( 1 ), which at least one on the membrane ( 1 ) mounted sensor ( 2 ) for detecting by pressurizing the membrane ( 1 ) occurring deformations and at least one reinforcing region ( 11 . 13 ), in which one has the contour of the amplification area ( 11 . 13 ) passing through recess ( 21 ) is formed, in which the sensor ( 2 ) is at least partially included. A pressure transducer according to claim 1, wherein the sensor ( 2 ) in the recess ( 21 ) is recorded in such a way that it transmits one via the sensor ( 2 ) continuation of the contour of the amplification area ( 11 . 13 ) cuts. A pressure transducer according to claim 1 or 2, wherein the gain region ( 11 . 13 ) centrally on the membrane ( 2 ) is trained. Pressure transducer according to one of the preceding claims, wherein the sensor ( 2 ) at a side of the membrane facing away from the pressure to be measured ( 1 ) is arranged. Pressure transducer according to one of the preceding claims, wherein the membrane ( 1 ) two gain areas ( 11 . 13 ), one of which ( 11 ) centrally on the membrane ( 2 ) and the other ( 13 ) in the edge region of the membrane ( 2 ) is trained. A pressure transducer according to any one of the preceding claims, wherein the gain region (s) (e) 11 . 13 ) in one piece with the membrane ( 2 ) is / are formed. Pressure transducer according to one of the preceding claims, wherein the recess ( 21 ) at a site of great deformation on the membrane ( 1 ) is located. Pressure transducer according to one of the preceding claims, wherein the recess ( 21 ) a groove ( 21 ) which at least partially enters the gain region ( 11 . 13 ). Pressure transducer according to claim 8, wherein the groove ( 21 ) longitudinally through the reinforcement region ( 11 . 13 ) extends therethrough. Pressure transducer according to one of the preceding claims, wherein the membrane ( 1 ) is pressurized by a medium. Pressure transducer according to one of the preceding claims, wherein the reinforcement region ( 11 . 13 ) is circular-cylindrical, wherein the sensor ( 2 ) is disposed on the continuation of the circumference line of the amplification area. A pressure transducer according to claim 11, wherein the gain region ( 11 . 13 ) and the membrane ( 1 ) are cylindrical, wherein the base of the membrane ( 1 ) and the gain range ( 11 . 13 ) are concentric circles. Pressure transducer according to one of the preceding claims, wherein the sensor ( 2 ) is a DMS, a DFS and / or a PRS. Pressure transducer according to one of the preceding claims, wherein the sensor ( 2 ) is a chip, which consists of a geometric offset arrangement of preferably four semiconductor elements, of which two resistors in parallel and both resistor pairs are arranged at an angle of 90 ° to each other, such that the resistor pairs undergo resistance changes with different signs that the absolute difference of the resistances is maximum and that they are electrically connected in a bridge circuit, preferably Wheatstone bridge. Pressure transducer according to one of the preceding claims, wherein the membrane ( 1 ) has a reinforced edge region in which recesses are placed for sensors connected to the corresponding sensor ( 2 ) in the corresponding recess ( 21 ) of the amplification area ( 11 . 13 ) are interconnected. Pressure transducer according to claim 15, wherein the edge region is cylindrical and has a circular ring as the base surface concentric with the base surface of the membrane ( 1 ). Pressure transducer according to one of the preceding claims, wherein the membrane ( 1 ) is laminated with PTFE. Pressure transducer according to one of the preceding claims, wherein the membrane ( 1 ) is coated with Au, Ag, PT and / or Ta. Pressure transducer according to one of the preceding claims, wherein the membrane ( 1 ) is provided as part of a container wall in particular for the measurement of levels or container pressures.