Classifications

• • 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
  • G01L19/0627—Protection against aggressive medium in general
  • G01L19/0645—Protection against aggressive medium in general using isolation membranes, specially adapted for 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
  • G01L19/144—Multiple part housings with dismountable parts, e.g. for maintenance purposes or for ensuring sterile conditions

Definitions

• Diaphragm seal in particular diaphragm seal
• the present invention relates to a diaphragm seal having an upper part and a lower part, which together define a housing interior in the assembled state, and with a membrane for arrangement between the upper and the lower part for the separation of the housing interior in an upper and a lower part of the room.
• the present invention further relates to a membrane for use in a pressure gauge, pressure control valve or diaphragm seal or diaphragm seal.
• Diaphragm seals are devices that are used in pressure measurement for pressure measurement of neutral and aggressive media. They are usually used in conjunction with a pressure sensor, in particular with a pressure gauge, the pressure of liquid or gaseous media, which within vessels
• a typical application concerns pipe pressure measurement within a pipe in which chemically highly reactive, toxic or environmentally harmful media are conducted.
• One of the main tasks of the diaphragm seal is to prevent the advance of the medium to the pressure sensor. This is necessary in particular when the measuring medium is a chemically reactive medium which, in the case of direct contact, can lead to destruction of the pressure sensor. Frequently, the diaphragm seal also serves to thermally decouple the pressure sensor from the measuring medium.
• Diaphragm seals of the above type usually have an upper part and a lower part, which together serve as flanges, between which a membrane is arranged or clamped.
• the membrane separates the housing interior into an upper part of the room, which is usually connected to the pressure sensor, and into a lower part of the room into which the measuring medium can penetrate.
• the upper part of the room is filled with a buffer liquid or with a pressure transfer liquid in order to transfer the pressure exerted on the membrane by the measuring medium in the lower part of the room to the pressure sensor. This allows accurate pressure measurement.
• FIG. 6 and 7 A common problem is the nature of the connection of the upper and the lower part of the diaphragm seal.
• Fig. 6 and 7 two known from the prior art pressure transmitter of the type mentioned above are shown schematically.
• the upper part 12 'of the diaphragm seal is connected via a thread to the lower part 14' of the diaphragm seal.
• this type of connection has been found to be detrimental, since it comes due to the screw connection between the upper part 12 'and the lower part 14' to a torsional movement of the clamped membrane between them. This torsional motion often leads to a drape on the membrane, which can lead to damage to the membrane and thus leaks in the overall system.
• FIG. 7 shows a further example of a pressure transmitter of the type mentioned above, in which the disadvantages mentioned with respect to the example shown in Fig. 6 have been attempted to eliminate that instead of a thread between the upper and the lower part 12 ', 14 '.
• Fig. 7 shows a further example of a pressure transmitter of the type mentioned above, in which the disadvantages mentioned with respect to the example shown in Fig. 6 have been attempted to eliminate that instead of a thread between the upper and the lower part 12 ', 14 '
• Several parallel to the longitudinal axis of the diaphragm seal aligned clamping screws are used to clamp the upper part 12' with the lower part 14 'with each other.
• This has the particular advantage that the membrane is loaded only in the axial direction, that is parallel to the longitudinal axis of the diaphragm seal. A drape within the membrane is therefore excluded, in contrast to the example shown in FIG.
• the example of the pressure transmitter shown in FIG. 7 is therefore preferable to the example shown in FIG.
• a large number of such clamping screws is required. This is not only disadvantageous in terms of production, but also increases the assembly effort. Even when changing individual components, such as the membrane, it is therefore relatively long assembly or repair times.
• this object is achieved by a pressure transmitter of the type mentioned above, wherein the pressure transmitter has a separate from the upper and lower part union nut with an internal thread, which corresponds to an arranged on the upper and / or lower part of external thread, to connect the upper and lower part with the union nut.
• the above object is achieved by a membrane for use in a pressure gauge, pressure control valve or a pressure transmitter, wherein the membrane is configured substantially circular and arranged along its outer periphery seal lace, which has a substantially wedge-shaped or swallowtail-shaped cross section.
• the diaphragm seal according to the invention thus has a three-piece housing construction with upper, lower part and a separate union nut.
• the upper and lower parts of the diaphragm seal housing still act as flanges for the diaphragm fixed therebetween. Due to the union nut, however, the membrane is loaded similarly to the example shown in FIG. 7 only in the axial direction, that is to say parallel to the longitudinal axis of the pressure mediator. A drape of the membrane as in the example shown in Fig. 6 is thereby effectively prevented.
• the diaphragm seal according to the invention is also advantageous over the example shown in FIG.
• the chosen formulation that the internal thread of the union nut corresponds with an arranged on the upper and / or lower part of the external thread is to be understood that the internal thread corresponding external thread can be arranged either on the upper part or on the lower part, or on the upper part and can be arranged on the lower part.
• the terms "upper part” and “lower part” are used essentially for the terminological differentiation of these two components, but are not intended to be restrictive with respect to their geometrical or spatially absolute Arrangement to be understood.
• the external thread is arranged only on one of the two components, that is, either on the upper part or on the lower part, on the respective outer side.
• the internal thread is preferably arranged on an inner side of the union nut.
• the union nut has a peripheral part, on the inside of the internal thread is arranged, and a bottom part, which extends transversely to the peripheral part and is adapted, in the assembled state of the diaphragm seal on the upper part or on the lower part a Apply force in the longitudinal direction of the diaphragm seal to clamp the upper part and the lower part together.
• the union nut is screwed to the upper part.
• the bottom part of the union nut exerts a force in the longitudinal direction of the diaphragm seal on the lower part in order to press this parallel to the longitudinal direction of the diaphragm seal against the upper part.
• the union nut is screwed to the lower part. In the latter case, the bottom part of the union nut in the mounted state then exerts a force on the upper part in order to press it parallel to the longitudinal direction of the pressure mediator against the lower part.
• the upper part has a connection element for connecting a pressure sensor, wherein the external thread is arranged on the upper part.
• connection element can be designed in many ways. For example, this may be a thread to which the pressure sensor is screwed. However, the pressure sensor, usually a manometer, can also be attached in another way to the connection element, for example by gluing or jamming with the upper part.
• the arrangement of the external thread on the upper part of the diaphragm seal housing offers in this case the advantage that the nut is slipped from below over the lower part, so that only the union nut and the lower part of the upper part must be removed to replace the membrane and the pressure sensor with the upper part can stay connected.
• the upper part is stressed during operation of the diaphragm seal in this case only to train, which is advantageous from a mechanical point of view.
• the pressure transmitter additionally comprises an anti-rotation means, which prevents a rotational movement of the upper part relative to the lower part during assembly of the union nut.
• the anti-rotation means simplifies the assembly. In essence, however, the anti-rotation means has the advantage that it does not come to a slipping or twisting of the membrane to be determined between the upper part and the lower part during assembly. This in turn serves the purpose of preventing a drape or a twisting of the membrane.
• the anti-rotation means having mutually corresponding counterparts of a tongue and groove connection, which are arranged on the upper and lower part.
• Such a tongue and groove connection is to be understood broadly in the present case.
• the tongue and groove connection can be designed in many ways. Ultimately, this should avoid twisting the upper part relative to the lower part about the longitudinal axis of the diaphragm seal during screwing the nut.
• one or more webs may be distributed on the upper side of the lower part over its circumference, which engage in the assembled state of the pressure transmitter in corresponding recesses on the underside of the upper part.
• the webs may as well be about bolts, which engage in corresponding recesses. At the locations of the recesses may preferably on the upper part arranged external thread to be interrupted.
• the grooves or recesses are provided on the lower part and the associated springs, webs or bolts are arranged on the upper part.
• the membrane is configured substantially circular and has a sealing cord arranged along its outer circumference, which has a substantially wedge-shaped or dovetail-shaped cross-section.
• the wedge-shaped or dovetail-shaped cross-section preferably spreads outwards in the radial direction of the membrane.
• the sealing cord acts as a retraction protection to keep the membrane during operation in its position between the upper part and lower part.
• a wedge-shaped or dovetail-shaped cross-sectional shape of the sealing cord causes in particular that the membrane is not only clamped at individual pressure points between the upper part and the lower part, but can be fixed along an inclined plane on the upper part or on the lower part. Leaks at the contact surfaces between the membrane and the upper part or the lower part can thereby be prevented even more effective.
• fewer internal stresses are generated within the membrane as a result of the clamping between upper and lower part, which in turn has an advantageous effect on the measuring accuracy. The likelihood of membrane rupture is also reduced.
• the upper part has on a lower side a first clamping surface for engagement with the membrane and the lower part has on a top side a second clamping surface for engagement with the membrane, wherein the first and the second clamping surface together form a substantially wedge-shaped or dovetail-shaped receptacle for clamping the sealing cord between the upper and the lower part in the assembled state of the diaphragm seal.
• the lower part on an upper side surrounding the longitudinal axis of the diaphragm seal first clamping surface for bearing the membrane on the lower part, wherein the first clamping surface is inclined at an angle with respect to the longitudinal axis of the diaphragm seal and in the lower part of a recess forms, which deepens in the radial direction of the diaphragm seal to the outside.
• An inclination of this first clamping surface is basically sufficient.
• the upper part also has a second clamping surface revolving around the longitudinal axis for abutment with the membrane on the upper part, wherein the second clamping surface is inclined at an angle with respect to the longitudinal axis and forms a depression in the upper part Radial direction of the diaphragm seal recessed to the outside.
• the two clamping surfaces thus preferably form a receptacle whose profile corresponds to the above-mentioned profile of the sealing cord of the membrane.
• Both clamping surfaces are preferably formed as radially encircling clamping surfaces. They form an inclined plane, so to speak. This offers in particular the advantage that the membrane during assembly due to a sliding of the wedge-shaped sealing cord at the two clamping surfaces in the radial direction can expand evenly. Should there be a decrease in the clamping force between the upper part and the lower part, for example, by gradual compliance of the material of the upper and the lower part, the membrane or the sealing cord of the membrane along the two inclined clamping surfaces can slide to radial direction automatically reposition.
• the union nut is substantially symmetrical to the longitudinal axis of the diaphragm seal and has on an inner side a circumferential around the longitudinal axis first contact surface which corresponds to a provided on a lower side of the lower second contact surface and this in the assembled state of the pressure transmitter contacted, wherein the first and the second contact surface are inclined with respect to the longitudinal axis at an angle of less than 90 °. For this angle, in particular 0 ° ⁇ ⁇ 90 °.
• the two contact surfaces are thus preferably formed obliquely with respect to the longitudinal axis of the pressure transmitter. Both contact surfaces are preferably around conical surfaces.
• the two contact surfaces essentially serve to transmit the force exerted by the union nut in the mounted state on the lower part to press the lower part parallel to the longitudinal axis of the diaphragm seal against the upper part.
• the inclination of the two contact surfaces in relation to the longitudinal axis of the diaphragm seal causes a similar advantage as the above-mentioned clamping surfaces between the diaphragm and the upper and lower part.
• the inclination of the two contact surfaces to counteract in particular a material relaxation of the upper and lower part, which often occurs especially in plastics.
• the lower part is at least partially formed of a corrosion-resistant material.
• the upper part and the lower part may be formed of different materials. Since, as already mentioned above, only the lower part of the room in the interior of the lower part comes into contact with the measuring medium, a more favorable material can be used for the upper part, which does not necessarily have to be resistant to corrosion.
• the upper part may be at least partially made of polypropylene.
• the lower part is preferably at least partially made of polyvinylidene fluoride (PVDF), polyvinyl chloride (PVC), polyethylene (PE) or stainless steel.
• PVDF polyvinylidene fluoride
• PVC polyvinyl chloride
• PE polyethylene
• the lower part can also be made of polypropylene (PP). It is understood that a variety of other plastics and metals and metal alloys can be used for the upper part and the lower part.
• a first side of the membrane which faces the lower part of the room in the installed state of the pressure transmitter, a corrosion-resistant material, wherein a second side of the membrane, which faces the upper part of the room in the mounted state of the pressure transmitter, has a different material.
• the membrane is made of an elastomer, in particular of ethylene-propylene-diene rubber (EPDM), which is formed on the lower part of the room facing side of the membrane with a corrosion-resistant material, in particular of polytetrafluoroethylene (PTFE), coated.
• EPDM ethylene-propylene-diene rubber
• PTFE polytetrafluoroethylene
• the present invention also relates to the membrane itself, which is configured substantially circular and has a sealing cord arranged along its outer circumference, wherein the sealing cord has a substantially wedge-shaped or dovetail-shaped cross-section.
• This membrane can be used not only for the above-mentioned diaphragm seal or diaphragm seal, but also in pressure gauges or pressure control valves are used.
• the wedge-shaped or dovetail-shaped cross-section of the sealing cord expands outwards in the radial direction of the membrane.
• the membrane is preferably made of an elastomer, in particular of ethylene-propylene-diene rubber (EPDM), which is coated on one side of the membrane with a corrosion-resistant material, in particular polytetrafluoroethylene (PTFE).
• EPDM ethylene-propylene-diene rubber
• PTFE polytetrafluoroethylene
• 1 shows a schematically illustrated application of a pressure transmitter according to the invention
• 2 shows an embodiment of the pressure transmitter according to the invention including pressure sensor in a front view.
• FIG. 3 shows an exploded view of the embodiment of the pressure transmitter according to the invention shown in FIG. 2;
• FIG. 4 shows a partial sectional view of the embodiment of the pressure transmitter according to the invention shown in FIG. 2;
• FIG. 5 shows an embodiment of a membrane according to the invention for use in the pressure transmitter in a perspective view (FIG. 5A), a plan view (FIG. 5B), a sectional view (FIG. 5C) and in a detailed sectional view (FIG. 5D);
• Fig. 6 shows a first example of one already known from the prior art
• Fig. 7 shows a second example of an already known from the prior art
• a preferred embodiment of the pressure transmitter according to the invention is designated in its entirety by the reference numeral 10.
• Fig. 1 shows schematically a typical application of the diaphragm seal according to the invention 10.
• the pressure transmitter 10 is mounted therein on a pipe 16, which is flowed through by a pressure-loaded measuring medium, such as a gas or a liquid.
• a pressure sensor 18 is also attached, by means of which the pressure of the guided in the pipeline 16 measuring medium is measured.
• the pressure sensor 18 is usually a conventional pressure gauge. In the present case, an analogue manometer is shown, which of course may also be a digital pressure gauge.
• the use of a pressure transmitter 10 is particularly necessary if it is in the measuring medium is a chemically reactive, toxic or environmentally harmful medium, which should not come into direct contact with the pressure sensor 18.
• the pressure averager 10 fulfills in particular the task of physically and thermally separating the measuring medium from the pressure sensor 18, but nevertheless passing on or transferring the pressure of the measuring medium to the pressure sensor 18 as loss-free as possible.
• the diaphragm seal 10 has an upper part 12, a lower part 14, a diaphragm 20 and a union nut 22.
• the upper part 12 and the lower part 14 act as flanges, between which the membrane 20 can be fixed in the assembled state.
• the separate union nut 22 is used to connect the upper part 12 with the lower part 14.
• Fig. 4 shows a partial sectional view of the diaphragm seal 10.
• the housing interior 24 is through the membrane 20 in an upper part of space 26 and a lower room part 28 separated.
• the measuring medium flows through an opening provided in the lower part 14 opening 30 in the lower part of the room 26 and strikes a bottom 32 of the membrane 20.
• the membrane 20, which is preferably at least partially made of an elastomer or other elastic material, As a result, it bulges upward in the direction of the upper volume part 26, thereby passing on the pressure exerted by the measuring medium on a buffer liquid or pressure transfer fluid (not shown) which is filled in the upper volume part 26.
• the pressure or the pressure change of this usually harmless buffer liquid can then be determined by means of the pressure sensor 18.
• the pressure transmitter 10 according to the invention is characterized in particular by its housing structure. Because of the use of the separate union nut 22, it is in fact possible to load the upper part 12 and the lower part 14 only on tensile pressure along or parallel to the longitudinal axis 34 of the diaphragm seal 10.
• the membrane 20 is only in the axial direction, ie parallel to the longitudinal axis 34 of the diaphragm seal 10, loaded when it is clamped in the assembled state between the upper part 12 and the lower part 14.
• an undesirable drape of wrinkles within the membrane 20 can be prevented. This not only prevents damage to the membrane 20, but also has an advantageous effect on the tightness at the interfaces between the membrane 20 and the upper or lower part 12, 14 and also advantageous to the accuracy of the diaphragm seal 10.
• the assembly in the diaphragm seal according to the invention 10 is also simplified in that only a nut 22 must be screwed to clamp the upper part 12 and the lower part 14 with each other.
• the assembly effort is thereby substantially simplified.
• the union nut 22 is screwed to the upper part 12.
• the upper part 12 has an external thread 36 which corresponds to an internal thread 38 arranged on the union nut 22 or cooperates in the assembled state.
• the external thread 36 is preferably arranged in the lower part of the upper part 12.
• the internal thread 38 is arranged on an inner side 40 of the union nut 22 (see in particular FIG. 3).
• the union nut 22 has a substantially cylindrical peripheral portion 42, on the inside 40 of the internal thread 38 is arranged. moreover the union nut 22 has a bottom part 44, which runs transversely to the peripheral part 42.
• the term "transverse” in this case is not necessarily necessarily to be understood as “vertical”, but as “not parallel”.
• the bottom part 44 of the union nut 22 is designed to exert an axial force component on the lower part 14 in the mounted state of the pressure mediator 10 in order to clamp the lower part 14 with the upper part 12.
• the force exerted by the bottom part 44 on the lower part 14 acts or has to act, but can also exert more force components in the radial direction or obliquely thereto.
• the external thread 36 on the lower part 14 and the union nut 22 from above over the top 12 over the diaphragm seal housing, so that the nut then with its bottom part 44 from above on the Upper part 12 presses to clamp the upper and the lower part 12, 14 with each other. This would be, so to speak, the kinematic reversal or an alternative embodiment to the embodiment of the diaphragm seal 10 shown in FIGS.
• the diaphragm seal 10 has hereafter optionally an anti-rotation means 46, which prevents a rotational movement of the upper part 12 relative to the lower part 14 during assembly of the union nut 22.
• This anti-rotation means 46 preferably has mutually corresponding counterparts 48, 50, which cooperate with each other in the manner of a tongue and groove connection.
• a counterpart 48 is realized as a recess or groove, which is arranged on the upper part 12.
• the other counterpart has a web or a feather key 50, which is arranged on the lower part 14.
• the anti-rotation means 46 as shown in Fig. 3, by a plurality over the circumference of the upper part 12 and the lower part 14 distributed, matching mating parts 48, 50 realized.
• the anti-rotation means 46 is intended to prevent the membrane 20 is undesirably twisted when screwing the nut 22 and twisted between the upper part 12 and the lower part 14. It is understood that the counterparts 48, 50 of the anti-rotation means 46 are not necessarily to the in Fig. 3 must be arranged. The counterparts 48, 50 can also be arranged at other locations, for example on the insides of the upper or lower part 12, 14. Furthermore, it is possible to arrange the recesses 48 on the lower part 14 and the associated webs or keys 50 on the upper part 12.
• the upper part 12, the lower part 14, the membrane 20 and the union nut 22 are preferably substantially symmetrical bodies, which in the assembled state are substantially symmetrical to the longitudinal axis 34 of the pressure mediator 10.
• substantially symmetrical it is to be understood here that this is merely a basic symmetry, whereby individual elements of said parts may also deviate from this basic symmetry.
• the membrane 20 has a sealing cord 52 arranged along its outer circumference, by means of which the membrane 20 is clamped between the upper part 12 and the lower part 14.
• the sealing cord 52 is a bulge arranged on the edge, which is arranged peripherally on the outer edge of the membrane 20.
• this sealing cord 52 has the purpose of acting as a retraction safeguard in the radial direction in order to prevent unintentional detachment of the membrane 20 from the clamping.
• the sealing cord 52 when viewed in cross-section of the membrane 20, has a substantially wedge-shaped or dovetail-shaped form.
• This wedge-shaped or dovetail-shaped cross-section widens in the radial direction of the membrane 20 to the outside.
• the upper part 12 and the lower part 14 have correspondingly at their lower or upper surface clamping surfaces 54, 56 which abut in the assembled state of the diaphragm seal 10 to the membrane 20 and to the sealing cord 52.
• the first clamping surface 54 arranged on the upper part 12 and the second clamping surface 56 arranged on the lower part 14 together form a substantially wedge-shaped or dovetailed receptacle for fixing clamp the sealing cord 52.
• Both clamping surfaces 54, 56 are preferably configured as conical surfaces, which are arranged radially circumferentially about the longitudinal axis 34. In both clamping surfaces 54, 56 are thus aligned obliquely to the longitudinal axis 34 surfaces, which act as a kind of inclined plane.
• the angle between these clamping surfaces 54, 56 and the longitudinal axis 34 of the diaphragm seal 10 preferably varies in the range of 1 ° to 89 ° particularly bevo risen in the range of 10 ° to 60 °.
• the diaphragm 20 can move slightly in the radial direction, without causing leaks, if the materials of the upper or lower part 12, 14 in the course of Give in slightly.
• the last-mentioned property is to be regarded as one of the main advantages of the wedge-shaped or dovetail-shaped geometry.
• a similar effect is realized by corresponding contact surfaces on the lower part 14 and the union nut 22.
• the union nut 22 On the inside of the bottom part 44, the union nut 22 has a circumferential around the longitudinal axis 34 first contact surface 58, with the union nut 22, the lower part 14 is contacted in the assembled state or pressed against the upper part 12.
• the lower part 14 has correspondingly a second contact surface 60, which is also designed as a conical, radially around the longitudinal axis 34 circumferential surface and is arranged on the underside of the lower part 12.
• the first and second contact surfaces 58, 60 are both aligned obliquely to the longitudinal axis 34. In other words, the first and second contact surfaces 58, 60 are inclined at an angle of less than 90 ° with respect to the longitudinal axis 34.
• Such an inclination of the contact surfaces 58, 60 is particularly advantageous if the union nut 22 and / or the lower part 14 are formed of plastic and it during the life of the diaphragm seal 10 due to relaxation of the plastics to smaller, relative displacements Components can come. In In such cases, the clamping surfaces 58, 60, which act as inclined planes, allow sliding against one another without causing leaks.
• Fig. 5 shows the membrane 20 in a perspective view (Fig. 5A), a bottom plan view (Fig. 5B), in a sectional view (Fig. 5C) and in a detailed sectional view (Fig. 5D).
• the membrane 20 is preferably designed circular.
• the sealing cord 52 extends along its outer periphery.
• the wedge-shaped or dovetail-shaped cross section of the sealing cord 52 which is already more detailed above, can be seen in more detail in particular in FIG. 5D.
• the membrane is preferably formed of an elastomer, in particular ethylene-propylene-diene rubber (EPDM).
• EPDM ethylene-propylene-diene rubber
• the membrane 20 is preferably coated with a corrosion-resistant material, in particular of polytetralfluoroethylene (PTFE).
• PTFE polytetralfluoroethylene
• This coating 62 may be vulcanized.
• this optionally has one or more concentric stiffening ribs 64.

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• Measuring Fluid Pressure (AREA)

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• 2014
  • 2014-03-12 DE DE102014103310.8A patent/DE102014103310A1/de active Pending
• 2015
  • 2015-03-10 WO PCT/EP2015/054909 patent/WO2015135910A1/de active Application Filing

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