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WO2022037860A1 - Capteur de mesure de pression différentielle - Google Patents

Capteur de mesure de pression différentielle Download PDF

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Publication number
WO2022037860A1
WO2022037860A1 PCT/EP2021/069985 EP2021069985W WO2022037860A1 WO 2022037860 A1 WO2022037860 A1 WO 2022037860A1 EP 2021069985 W EP2021069985 W EP 2021069985W WO 2022037860 A1 WO2022037860 A1 WO 2022037860A1
Authority
WO
WIPO (PCT)
Prior art keywords
pressure
capillaries
chamber
differential pressure
auxiliary
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/EP2021/069985
Other languages
German (de)
English (en)
Other versions
WO2022037860A9 (fr
Inventor
Thomas Uehlin
Florian Gutmann
Alexander Beck
Igor Getman
Benjamin Mack
Michael Noack
Michael Hügel
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Endress and Hauser SE and Co KG
Original Assignee
Endress and Hauser SE and Co KG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Endress and Hauser SE and Co KG filed Critical Endress and Hauser SE and Co KG
Publication of WO2022037860A1 publication Critical patent/WO2022037860A1/fr
Publication of WO2022037860A9 publication Critical patent/WO2022037860A9/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L13/00—Devices or apparatus for measuring differences of two or more fluid pressure values
    • G01L13/02—Devices or apparatus for measuring differences of two or more fluid pressure values using elastically-deformable members or pistons as sensing elements
    • G01L13/025—Devices or apparatus for measuring differences of two or more fluid pressure values using elastically-deformable members or pistons as sensing elements using diaphragms
    • G01L13/026—Devices or apparatus for measuring differences of two or more fluid pressure values using elastically-deformable members or pistons as sensing elements using diaphragms involving double diaphragm
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L19/00—Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
    • G01L19/0007—Fluidic connecting means
    • G01L19/0038—Fluidic connecting means being part of the housing
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L19/00—Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
    • G01L19/06—Means for preventing overload or deleterious influence of the measured medium on the measuring device or vice versa
    • G01L19/0618—Overload protection
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L19/00—Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
    • G01L19/14—Housings
    • G01L19/142—Multiple part housings
    • G01L19/143—Two part housings

Definitions

  • 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.
  • 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.
  • 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.
  • DE 3 222 620 A1 discloses a pressure difference measuring device which has a pressure measuring 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.
  • 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.
  • the device If the device is subjected 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 specified value as a result of an overload, then the pressure transmitter located below the separating diaphragm on the high-pressure side is Pressed liquid into its associated antechamber. 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.
  • 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.
  • the converter chamber is integrated into the measuring mechanism.
  • WO 2018/165122 A1 discloses a coplanar differential pressure sensor in which the pressure inputs with separating diaphragm and overload diaphragm are arranged in one plane - specifically in the end area facing the process - and not on opposite, parallel planes as in the previously mentioned 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.
  • the pressure-loaded center membrane weld can be dispensed with here, so that the measuring mechanism can be made in one piece.
  • the overload protection is also arranged in the measuring mechanism in this known solution, i.e. 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.
  • oil volume is chosen because the hydraulic transmission fluid is usually an almost incompressible oil, e.g. a silicone oil.
  • a coplanar differential pressure sensor for determining the differential pressure of two pressures with one measuring unit and one 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.
  • 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.
  • 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.
  • the measuring mechanism is housed in the process connection, and the converter chamber is integrated in the housing adapter.
  • the measuring mechanism is designed in one piece.
  • the measuring unit has a relatively simple and largely symmetrical or fully symmetrical structure.
  • 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.
  • the measuring mechanism and the converter chamber are coupled only via the connecting capillaries and the auxiliary capillaries (6-tube system)—at least in the configuration without an intermediate module. 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.
  • 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.
  • the filling takes place via at least one filling opening in the converter chamber.
  • 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.
  • 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.
  • 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.
  • 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/separation membrane that can be used in connection with the solution according to the invention, among other things, is described, for example, in US Pat. No. 10,656,039 B2.
  • the connecting capillaries and the auxiliary capillaries run essentially parallel to the longitudinal axis of the differential pressure sensor, starting from the measuring mechanism.
  • 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.
  • the change of direction and the crossing are preferably implemented by appropriately arranged transverse bores in the relatively small-sized converter chamber.
  • a block of material is arranged in the intermediate area between the measuring mechanism and the converter chamber.
  • the capillaries running longitudinally and transversely in the material block are capillary bores. Capillary tubes are preferred when the block of material is missing.
  • the connecting capillaries and/or the auxiliary capillaries arranged in the measuring unit and in the converter chamber are capillary bores.
  • 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.
  • an advantageous embodiment of the differential pressure sensor 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.
  • 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.
  • 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.
  • each filling hole is closed in a pressure-tight, gas-tight or at least liquid-tight manner via a closure element.
  • the closure 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 out, the required amount of transmission fluid can be reduced by introducing filling elements, e.g. filling rods, into the filling bores.
  • the connecting capillaries are designed in such a way that they electrically insulate the converter chamber from the measuring unit.
  • 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. With an additional insulating element, it can act 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.
  • 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.
  • the previously required isolating element e.g. a ceramic base, a glass base or a sufficiently isolating bond in the converter chamber can be omitted;
  • the pressure-sensitive element is preferably applied to a silicon base.
  • 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.
  • T hysteresis thermal behavior
  • static pressure error a lower static pressure error
  • 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.
  • 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 appropriately 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. It is also provided that the electrical connection pins or
  • Connecting lines from the electrical converter are guided 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. In addition, smaller PINs/encapsulation elements allow more PINs to be accommodated in the same space. This may also mean that less oil volume is required.
  • 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.
  • a corresponding pressure-sensitive element for measuring the static pressure is provided in the converter chamber.
  • 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.
  • FIG. 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
  • Fig. 2b the configuration shown in Fig. 2a in the event of excess pressure or overload
  • Fig. 2c a further illustration of the embodiment of the differential pressure sensor according to the invention shown in Fig. 2b,
  • Fig. 2d a more realistic representation of the deflection of the membranes in the case of an overpressure occurring on one side
  • Fig. 3a a longitudinal section in the area of the two front auxiliary capillaries
  • Fig. 3b a longitudinal section in the area of the two connecting capillaries
  • Fig. 5 Different representations of advantageous variants of how the electrical insulation between the measuring mechanism and the converter chamber is achieved
  • Fig. 6 different views and sections through a converter chamber with a unit for compensating for the static pressure
  • Fig. 7 the circuit of the electrical connections of the differential pressure measuring cell and the static pressure measuring cell
  • Fig. 8 a longitudinal section through a differential pressure sensor shown schematically
  • Fig. 1 the structure of a differential pressure sensor 1 according to the invention is outlined.
  • the differential pressure sensor 1 consists of a measuring mechanism 2 with a coplanar double diaphragm system 4a, 4b and a converter chamber 3.
  • the converter chamber 3 is arranged in the housing adapter 22, and the measuring mechanism 2 is integrated into the process connection 21.
  • Housing adapter 22 and process connection 21 are above a joint 20 is connected to one another in a pressure-tight and gas-tight manner, but at least in a liquid-tight manner.
  • 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.
  • 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. Connecting capillaries and auxiliary capillaries are only sketchily indicated in FIG. 1 and are therefore not provided with reference numbers.
  • Figures Fig. 2a, Fig. 2b and Fig. 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.
  • a coplanar double membrane system with two double membranes 4a, 4b is provided on or in an end region of the measuring unit 2 facing the process.
  • 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 diaphragms 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 is destroyed and the differential pressure sensor 1 is 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.
  • 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.
  • 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.
  • 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.
  • a hydraulic channel may be introduced in the contact surfaces of the overload membranes 6a, 6b or in the two membrane beds.
  • Fig. 2c is shown more realistically how the overpressure protection works.
  • the mode of operation can be seen even better in FIG. 2d.
  • 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 .
  • 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.
  • 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.
  • 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 applied to the plus side (+) of the pressure-sensitive element 15 can be defined or dimensioned via the restoring force of the overload membrane 6a, 6b (spring in the deflected state). This effectively counteracts the destruction of the pressure-sensitive element 13, usually a silicon chip.
  • 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.
  • dynamic brakes 18 can also be provided upstream of the pressure-sensitive element 13 .
  • 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.
  • 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 pressures occurring in the process pressure peaks.
  • the dynamic brakes 18 can be sintered metal inserts.
  • 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.
  • FIG. 3 shows a perspective view of an embodiment of the differential pressure sensor according to the invention.
  • FIG. 3a shows a longitudinal section in the area of the two front auxiliary capillaries.
  • FIGS. 3b and 3c show longitudinal sections in the area of the two connecting capillaries and in the area of the two rear auxiliary capillaries.
  • FIG. 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.
  • the pressures p1, p2 applied to 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.
  • six vertical capillary bores that is, parallel to the longitudinal axis of the differential pressure sensor 1
  • 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.
  • FIG. 4 shows a perspective view of the power feedthrough 23 and an exploded view of a cube-shaped configuration of the differential pressure measuring cell 12.
  • An insulating base (e.g. a ceramic base) 31 is connected to the bottom surface of a recess in the converter chamber 3 using 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 .
  • 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 reasons of explosion protection, for example. Furthermore, the insulation of the silicon chip 13 and its bonds 24 takes over the packing 33 with cover 34, the eg is made of a suitable plastic.
  • the connecting capillaries 10a, 10b designed as capillary tubes and the auxiliary capillaries 11a, 11b, 11c, 11d are shown below.
  • FIG. 5 shows different representations of advantageous variants of how the electrical insulation between the measuring mechanism 2 and the converter chamber 3 can be realized via insulation elements 25, preferably insulation tubes 25, adapted in or on the capillary tubes 17.
  • insulation elements 25 preferably insulation tubes 25, adapted in or on the capillary tubes 17.
  • 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.
  • the electrically insulating ceramic tubes 25 can be placed in the converter chamber 3 (Fig. 5a), in the intermediate area between the converter chamber 3 and the measuring unit 2 (Fig. 5c) or in the measuring unit 2 (Fig. 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 sensor i 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.
  • FIG. 6 shows a converter chamber 3 or its components and different sections through the converter chamber 3 or its components.
  • a measuring cell 27 is also provided for determining the static pressure.
  • the power feedthrough 23 is shown 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.
  • Two pins 1.1, 1.2 of the eight pins 26 can be connected without insulation, e.g. B. soldered, since they are on ground / housing potential.
  • the PINS 2 and 3 could be electrically connected together, ie in a common PIN, to potential (FIG. 7b). The electrical insulation then preferably takes place via a glazing. If the ground PINS 1.1, 1.2, which correspond to the PINS 1, 8, and the PINS 2, 3 for the voltage supply are combined, the two bridges are connected in parallel to the voltage supply. This circuit is shown in FIG. 7c
  • the interior space of the converter chamber 3 preferably has a diameter of ⁇ 10 mm, in particular ⁇ 8 mm.
  • 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.
  • 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.
  • FIG. 6c shows a cross section in the area of the differential pressure measuring cell 12, while FIG. 6d shows a section in the area of the ghip 27 for measuring the static pressure.
  • FIGS. 7a, 7b and 7c The circuits for the previously mentioned arrangements of the PINs 26 are shown in FIGS. 7a, 7b and 7c.
  • 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; a minimum of six PINs 26 (FIG. 7b) are required.
  • 7c shows a circuit with 7 PINs 26.
  • This intermediate solution has a separate plus supply but a common ground. The benefit of using a smaller number of PINs 26, it is clear 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.
  • a common PIN 26 can also be used for the ground connection.
  • FIG. 8 shows a longitudinal section through a differential pressure measuring sensor 1 shown schematically. Furthermore, the different zones AG to which the differential pressure measuring sensor 1 is exposed are listed in FIG. 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:
  • FIG. 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 FIG. 9 only the recesses 38 for the pins from the current bushing - are selected in such a way that galvanic isolation is ensured.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measuring Fluid Pressure (AREA)

Abstract

L'invention se rapporte à un capteur de mesure de pression différentielle (1) permettant de mesurer la pression différentielle entre deux pressions (p1, p2) à l'aide d'un mécanisme de mesure (2) et d'une chambre de transducteur (3); un système à double membrane coplanaire (4) doté de deux doubles membranes (4a, 4b) étant disposé sur ou dans une région d'extrémité côté processus (14) du mécanisme de mesure (2); une cellule de mesure de pression différentielle (12), dotée d'un élément sensible à la pression (13), étant disposée dans la chambre de transducteur (3); les deux doubles membranes (4a, 4b) étant chacune constituées d'une membrane de séparation (5a, 5b) et d'une membrane de surcharge (6a, 6b) disposée en aval de la membrane de séparation (5a, 5b) dans la direction de l'action de la pression; une première chambre de pression (7a) étant formée entre la première membrane de séparation (5a) et la première membrane de surcharge (6a), et une première chambre de pression supplémentaire (8a) étant formée entre la première membrane de surcharge (6a) et le corps principal (9); une seconde chambre de pression (7b) étant formée entre la seconde membrane de séparation (5b) et la seconde membrane de surcharge (6b), et une seconde chambre de pression supplémentaire (8b) étant formée entre la seconde membrane de surcharge (6b) et le corps principal (9); un premier capillaire de raccordement (10a) et un second capillaire de raccordement (10b) étant associés respectivement à la première chambre de pression supplémentaire (8a) et à la seconde chambre de pression supplémentaire (8b); les deux capillaires de raccordement (10a, 10b) transmettant hydrauliquement la pression à la chambre de transducteur (3); et un premier capillaire auxiliaire (11a) et un deuxième capillaire auxiliaire (11b) étant associés respectivement à la première chambre de pression supplémentaire (8a) et à la seconde chambre de pression supplémentaire (8b) afin de protéger l'élément sensible à la pression (13) d'une pression excessive sur un côté; la première chambre de pression (7a) et la seconde chambre de pression (7b) étant associées respectivement à un troisième capillaire auxiliaire (11c) et à un quatrième capillaire auxiliaire (11d); et, aux fins d'un raccordement hydraulique, le premier capillaire auxiliaire (11a) étant connecté au quatrième capillaire auxiliaire (11d) et le deuxième capillaire auxiliaire (11b) étant connecté au troisième capillaire auxiliaire (11c), les points de connexion étant agencés dans chaque cas dans la chambre de transducteur (3).
PCT/EP2021/069985 2020-08-17 2021-07-16 Capteur de mesure de pression différentielle Ceased WO2022037860A1 (fr)

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DE102020121583.5A DE102020121583A1 (de) 2020-08-17 2020-08-17 Differenzdruckmessaufnehmer
DE102020121583.5 2020-08-17

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DE102020133204A1 (de) * 2020-12-11 2022-06-15 Endress+Hauser SE+Co. KG Verfahren zum Herstellen eines Differenzdruckmessaufnehmers und entsprechender Differenzdruckmessaufnehmer

Citations (5)

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Publication number Priority date Publication date Assignee Title
DE3222620A1 (de) 1982-02-15 1983-08-25 Siemens AG, 1000 Berlin und 8000 München Druck- oder druckdifferenzmessgeraet mit einer vor ueberlastung geschuetzten drucksonsor-einrichtung
US20140083171A1 (en) * 2012-09-27 2014-03-27 Rosemount Inc. Pressure transmitter with fill tube
US20180259414A1 (en) * 2017-03-10 2018-09-13 Honeywell International Inc. Pressure sensor having overpressure protection with reduced output error
WO2018165122A1 (fr) 2017-03-10 2018-09-13 Honeywell International Inc. Capteur de pression présentant un corps de compteur coplanaire doté d'une protection du capteur contre la surpression
WO2018204304A1 (fr) * 2017-05-02 2018-11-08 General Electric Company Système de protection contre les surpressions

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10627302B2 (en) 2017-06-16 2020-04-21 Rosemount Inc. Pressure sensor module for high working pressure applications

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3222620A1 (de) 1982-02-15 1983-08-25 Siemens AG, 1000 Berlin und 8000 München Druck- oder druckdifferenzmessgeraet mit einer vor ueberlastung geschuetzten drucksonsor-einrichtung
US20140083171A1 (en) * 2012-09-27 2014-03-27 Rosemount Inc. Pressure transmitter with fill tube
US20180259414A1 (en) * 2017-03-10 2018-09-13 Honeywell International Inc. Pressure sensor having overpressure protection with reduced output error
WO2018165122A1 (fr) 2017-03-10 2018-09-13 Honeywell International Inc. Capteur de pression présentant un corps de compteur coplanaire doté d'une protection du capteur contre la surpression
US10656039B2 (en) 2017-03-10 2020-05-19 Honeywell International Inc. Pressure sensor having overpressure protection with reduced output error
WO2018204304A1 (fr) * 2017-05-02 2018-11-08 General Electric Company Système de protection contre les surpressions

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