DE3326448C2 - Pressure transducer - Google Patents

Abstract

A pressure sensor (1) (Fig. 1) has a chamber (4) which is provided with pressure connections (2, 3) and is divided into two by a membrane (5). The membrane is clamped with its membrane edge (10) between two capsule parts (7 and 8) surrounding the chamber (4). The capsule parts (7 and 8) are held together on the outside by clamping means (9). The membrane (5) is centrally connected to a displacement transducer (6). The clamping means (9) and the clamping point of the membrane (5) forming an annular sealing zone are arranged in such a way that the clamping forces emanating from the opposing points of application of the clamping means (9) arranged on the circumference lie on straight connecting or pressure lines, which are also preferably cut the sealing zone centrally. The circular impact surfaces of the clamping means and the annular sealing zone at the membrane edge (10) thus form concentric circles of the same diameter. As a result, lateral force components resulting from the bracing are largely avoided, so that an elastic bending of the capsule parts (7 and 8) due to the bracing is accordingly avoided. As a result, the temperature influence is kept small via the modulus of elasticity of the material of the capsule parts. In addition, the pressure transducer can be easily assembled or disassembled.

Description

The invention relates to a pressure transducer with a pressure connection and a membrane Chamber which is enclosed by two capsule parts and in which at least one capsule part has one The diaphragm coupled displacement transducer is arranged with the capsule parts at the edge in a circular ring Clamp the edge of the membrane in the clamping zone, circular in the circumferential direction, in the cross section U-shaped clamping means with their clamping legs overlap the fastening edges of the capsule parts and the opposing points of attack of the clamping legs and the clamping zone at least at undeformed clamping devices on an imaginary cylinder jacket lie.

A pressure transducer is already known from US-PS 40 72 056, in which, however, the position of the clamping point is disadvantageously dependent on the respective assembly force evokes. In addition, the capsule part itself can be elastically deformed, which is subject to a strong temperature influence due to the temperature coefficient of the modulus of elasticity of the components, so that measurement inaccuracies can also occur as a result.
Furthermore, one knows one from the CB-PS 9 27 075

3 4

Measurement arrangement in which the membranes are cemented in bility This results in a noticeable hysteresis and a modified embodiment provides that the

also a time and temperature dependency of the zero ring surface of the formations plane and parallel to the clamping

dotcs. ring plane, with its outer, the respective at a pressure sensor according to FR-PS15 82 509 5 gene clamping means closer edge in the assembly position in the

Although there is also a clamped membrane, the hollow cylinder containing the sealing zone lies through the

however, this is elastically mounted in the measuring direction, so that the deformations that occur during tensioning

that in principle high temperatures occur here. Only the outer edge of the ring comes in handy for tension rings

The US-PS 4041 761 shows to connect the cap for the application to wear. So that here too in

side parts separate clamping devices, which are designed as hook parts to desirably only have an annular

forms are. This overlap with their hooks there is a blow. It also occurs here

Edge of the capsule part and take hold of a deformation of the clamping device at the other end, but this is

the other capsule part acting on the flange. Impression outside the area of action on the mem-

Depending on the clamping force, there is also a wall clamping point in the sense of generating on the

dcrn the effective support in the diaphragm area radially 15 diaphragm acting transverse force components, which to

outwards until finally essentially the outer ones would result in an undesirable deflection. The edges of the capsule parts form the support. One embodiment provides that a capsule part

there are transverse forces with acting in the membrane plane roughly U-shaped in cross-section and the other, in particular

Force components that reinforce an undesirable special capsule part connected to the displacement transducer Can cause deformation of the membrane. 20 approximately plate-shaped, preferably with a mem- Finally, in this construction, projecting approaches are formed by the hook brand and that

Also screw the diaphragm, which is uneven over the circumference, parallel to its diaphragm plane on the side.

Force introduction present. offset has a clamping flange

The object of the invention is to provide a pressure transducer for the elastic deformation of that capsule half which to create, which carries a large zero point stability and 25 the displacement transducer, kept small, so that prakauch a slight temperature influence on the knife table no influence on the measurement occurs, Has result, so that the device also for sensitive preferably has the U-shaped in cross-section Measurement tasks can be used in low pressure ranges. Capsule part as U-side leg, an outer, axial In addition, the entire construction should be oriented, encircling approach to its front compartment in the structure and individual parts possibly also 30 side, preferably on the inner edge, with a ring attachment be easily interchangeable. Finally, despite the ho- a narrow, z. B. approx. 0.5 mm wide circular ring area If the accuracy requirements are met, a single series production is also provided as a sealing surface in the sealing zone be possible, the side that occurs is achieved by the fact that the assembly tolerances when working together the accuracy of the pressure absorption occurring elastic deformations in tight mers are practically not supposed to influence. 3s limits are kept and that on the other hand one

To solve this problem, a pressure sensor is formed with a narrow sealing zone, which is

suggested. in which the clamping legs of the clamping ring surfaces of the clamping rings are aligned, medium with impact edges of at their clamping A further embodiment provides that between

give no axially protruding formations on the membrane and the capsule parts a self-sealing

Attack fastening edges of the capsule parts, the 40 de contact is provided and the contact surfaces

have associated points of attack even with deformed, preferably polished surfaces. Especially

Clamping legs in one special thanks to the clamping zones in connection with the narrow sealing zones

running, imaginary cylinder. and the resulting high surface pressure on both

When the capsule parts are pressed together by the membrane on the outside, a good seal is achieved, ßcren clamping means is practically independent of the 45. If necessary, one can be in the separation area of the cape size the clamping force perpendicular to the outer side provided annular groove for receiving Tensioning forces running across the membrane and thus none of the protruding edge of the membrane clamping pan the measurement should be provided, which has a detrimental impact on the force of the force, the groove preferably only components. Assembly tolerances with regard to the clamping is partially filled with sealing compound. Thereby is power thus have no effects on the layer 50 on the outside an additional seal between the two Membrane, so that serial production of the sealing areas between the two membranes remains the same Quality is possible on both sides and the respective capsule parts.

An advantageous embodiment provides that the additional refinements of the invention are shown in FIG Clamping means spanning the edges of the capsule parts, and several other subclaims listed below.

wa radially oriented clamping rings with preferably 55 Itiend is the invention with its essential details

have blade-like formations. This is explained in greater detail on the basis of the drawing. It shows there are very narrow areas of application, the F i g. 1 shows a cross section of a pressure receiver

aligned and also largely in the middle 7u the Beruh displacement transducer,

Circular ring surfaces or the sealing zone of the other F i g. 2 a particular with regard to the clamping means

Components are positionable. 60 compared to FIG. 1 modified embodiment The projections expediently have those of a pressure transducer, Clamping rings, each with a capsule part in assembly position- F i g. 3 and 4 cross-sectional views of a pressure

Development facing, obliquely formed annular surfaces, record «with displacement transducer, where F i g. 3 a pre

in particular the radially outer edge of this assembly position and FIG. 4 a final assembly position

inclined annular surface protrudes axially and shows a cutting edge 65, and

like impact edge forms. This gives FIG. 5 a representation corresponding approximately to FIG. 1,

Desirably the essentially circumferential but here with an additional outer seal, A pressure transducer 1 has a pressure connection with

5 6

Sen 2 and 3 provided chamber 4. In this is screw 20 corresponds to the

a membrane S, which is clamped in at the edge and the intended assignment of the components

is coupled approximately centrally with a displacement transducer 6. enough.

The chamber 4 is essentially by two cap- In the embodiment according to FIG. 3 and 4 are enclosed in side parts 7 and 8, the edges of which plan the clamping rings 116 with a modification to FIG. Cross-section of U-shaped clamping means 9 are connected to annular surfaces extending parallel to the clamping ring plane and to clamp the membrane edge 10 between them. 18 in the in F i g. 3 from the pre-assembly position shown - The clamping means 9 have clamping rings 11, which are formed. The pre-assembly position here means that the capsule parts 7 and 8 act on the outside and the clamping rings 11a are not yet under pressure. Press against each other. According to FIG. 1 these io versus shows F i g. 4 shows the final assembly position with tightened clamping rings 11, which have an external thread 12, in a particular clamping screw 20. It can be seen that the receiving housing 13 with internal thread 14 is screwed in, the clamping rings Ub, deformed approximately like a disk spring. Ben between the two capsule parts 7 and 8, so that only the radially outer ring edge is located, there is an annular circumferential sealing zone 15, capsule part 7 on the one hand and the capsule part 8 on the other hand in which the membrane edge is applied tightly between the capsules essentially the same parts 7 and 8 are clamped conditions as in the embodiment according to The application zone of the clamping means 9 in FIGS. 2 available. The deformation of the clamping rings 11 b capsule parts 7 and 8 and the sealing zone 15 form co- in F i g. 4 is somewhat not to scale for the sake of clarity, axial annular surfaces of the same diameter. When shown

This means that the opposing 20 The capsule parts 7 and 8 are designed differently from the opposing connections according to FIGS the clamping forces emanating from the capsule parts 7 and 8 have an approximately U-shaped cross section, lie on straight connecting lines N , which also intersect the sealing zone 15, which is approximately plate-shaped during the other capsule part 7. This arrangement results in 25 formed and connected to the displacement transducer 6 ben with respect to the capsule parts 7 and 8 is practical. As a result of the essentially lug-free, plate-shaped bending moments through which the capsule parts are elastically formed, the capsule part 7 becomes elastic, concave or convex. The deformations in the clamping together of the capsule parts connecting line runs as a sheath line of a N overall very small and thus an undesirable influence covered cylinder jacket also perpendicular to the membrane plane 30 of the measurement result correspondingly small gehal- M or to which Einspannflanschen 10. This results in ten.

so practically no force influencing the measurement. The membrane 5 faces its membrane plane M components. This results in a high temperature membrane edge 10 which is laterally offset parallel thereto influence on the modulus of elasticity of the material on. The capsule parts are also in accordance with this design avoided. Thus, pressure-absorbing side parts 7 can be formed, with the capsule part 7 on the membrane side mer with high sensitivity or also for a very low approach 28 and the capsule part 8 the previous one Realize pressures. thought to have a U-shaped cross-section.

Despite this due to the structure of the pressure transducer, the membrane comes in the middle between the parallel

Achievable high measurement sensitivity is the pressure IeI extending to the inner walls of the capsule part

transducer particularly simple in construction. Lie on top of it. These inner walls form stop surfaces

it is easy to assemble and also for the membrane to which it attaches in the event of pressure overload.

z. B. to replace individual parts, can easily support dismantling. This increases the overload capacity

animals. This is especially true for a customer of the membrane without significantly influencing the

service advantageous. The entire system can be increased considerably with the measurement accuracy

for example by unscrewing the lower clamping ring 45 that the capsule, which is approximately U-shaped in cross section

ges 11 dismantle, after removing the 8 can be formed from a base plate on which the

System practically disintegrates into all important individual parts.

can then easily the membrane 5 or the path can. These two parts are easy to manufacture,

receiver 6 exchanged with the upper capsule half 7 In addition, it is advantageous that the cheap matc-

will. A rial properties is then just as quick again because of the low, necessary Bc-

Assembly possible, whereby the training is retained. In particular, stay on

individual parts a difficult readjustment is avoided. both sides the z. B. obtained rolled tops, so

To the area of application of the clamping means that no or only a small amount under the influence of temperature

to keep the capsule parts 7 and 8 as narrow as possible, delay occurs. The upper capsule part 7 also exists

have the clamping rings 11 on the membrane side according to FIG. 1 55 from a punched plate, in which to form the

bead-like formations 16 and, according to FIG.

such impact edges 17 on. This ringför- As a U-side leg, the capsule part 8 has a

moderate impact edges 17 form the outer circumferential projection 21, on the end face of the

Boundary edge of an obliquely formed Ringflä- inner edge an annular shoulder 22 with a narrow, z. B. approx.

before 18. 60 0.5 mm wide circular ring surface as sealing surface 23

As a modification of the embodiment according to FIG. 1, this narrow circular ring surface results in a are in Fig. 2 comparatively high surface pressure for tensioning the two clamping rings, through which one-11a On the one hand, a good seal is distributed against each other on the circumference, but on the other hand not yet rather 19 intended for clamping screws 20. Both in notch effect on the membrane occurs as this occurs at F i g. 1 as well as in FIG. 2 it can be seen that the capsule 65 distributes one with the clamping ring impacting edges 7 and 8 have an outer diameter that would be the same shape. Especially with thin about The narrow circular ring sealing flange acts on the clear inside diameter of the receptacle membrane 5 13 or the clear distance between diametrical clamping before 23 of the ring attachment 22 through the membrane

by. There is also the possibility of a tight seal without any additional seal to achieve. The contact ring surfaces between the capsule parts 7 and 8 and one side of the membrane edge IO thus form a self-sealing contact. In this case it is useful if the contact surfaces have polished surfaces. This seal-free embodiment also favors one particularly easy assembly of the pressure transducer.

But there is also the possibility that the area of the contact surfaces with a thin metal layer, in particular made of softer than the material of the capsule parts 7, 8 and / or that of the membrane 5 Metal is coated. B. tin, lead, aluminum, indium, gold, copper and the like in Question. Paint, plastic, Rubber and the like may be provided. These additional sealants are preferably used with the appropriate Parts connected by coating or the like, so that no loose sealing parts are present.

F i g. FIG. 5 shows another embodiment of a pressure transducer roughly comparable to that in FIG. 1, where Here, however, a seal 25 is provided on the outside in the separating area 24 between the capsule parts 7 and 8 This seal 25 is introduced into an annular groove 26, which is formed in particular by the narrow annular shoulder 22 or is limited in Figure 5 is also clearly visible that the membrane edge 10 to the outside via the Sealing surface 23 protrudes This protruding end is in the seal 25, for example by a synthetic resin adhesive or the like. Is embedded. This creates an additional seal between the two Membrane edge surfaces and the two capsule parts 7 and 8. The seal 25 only fills the annular groove 26 partially off. Compared to a complete filling of this annular groove 26 is avoided that by the seal 25 against the groove side ring surfaces formed by the capsule parts 7 and 8 compressive stresses develop.

Due to the additionally provided outer sealing area accommodated in the annular groove 26, this is after Well protected from the outside

As already mentioned, the entire pressure transducer can be dismantled by removing one of the clamping rings. In the embodiments according to FIG. 1 and 5 it is provided that the clamping ring 11 facing away from the displacement transducer 6 forms the removable ring For this purpose, it has access openings 27 for the engagement of a twisting tool. The upper The clamping ring 11 can then, if necessary, be unscrewed by hand without any auxiliary tools.

Overall, the pressure transducer 1 has particularly good properties with regard to zero point stability and also with regard to a low temperature influence. These problems were from the electrical / electronic side already solved, so now through the mechanical design of the pressure transducer the good electrical properties of the measuring system for This combination results in an overall high measurement sensitivity and also a particularly good measurement stability

Despite these essential metrological advantages, the pressure transducer 1 has a simpler structure and is also much easier to assemble and dismantle.

For this purpose 3 sheets of drawings

Claims (14)

Patent claims: 1.Pressure transducer with a chamber provided with pressure connections and a membrane, which is enclosed by two capsule parts and in which a displacement transducer coupled to the membrane is arranged on at least one capsule part, the capsule parts clamping the edge of the membrane in an annular clamping zone in Circumferential clamping means with a U-shaped cross-section overlap the fastening edges of the capsule parts with their clamping legs and the opposing points of application of the clamping legs and the clamping zone lie on an imaginary cylinder jacket, at least when the clamping means are not deformed, characterized in that the clamping legs of the clamping means have impact edges (17) attack on their clamping legs axially protruding formations (16) on the fastening edges of the capsule parts and that the associated points of attack with deformed clamping legs in an imaginary cylinder running through the clamping zones in which (N) lie. 2. Pressure transducer according to claim 1, characterized in that the clamping means (9) the capsule parts edges overlapping, approximately radially oriented clamping rings (11, 11a, 116) with preferably blade-like Have projections (16). 3. Pressure transducer according to claim 2, characterized in that the clamping rings (11) have an external thread (12) and can be screwed into a receiving housing (13) with an internal thread (14). 4. Pressure transducer according to claim 2 or 3, characterized in that the clamping rings (lla) on the outside have mounting holes (19) for clamping screws (20) distributed around the circumference. 5. Pressure transducer according to one of claims 2 to 4, characterized in that the projections of the clamping rings (lla) each have a capsule part (7 or 8) have inclined annular surfaces (18) facing in the assembly position, and that in particular the radially outer edge of this inclined annular surface protrudes axially and a cutting edge Acting edge (17) forms 6. Pressure transducer according to one of claims 1 to 5, characterized in that the annular surface (18) of the projections is arranged flat and parallel to the clamping ring plane and that its outer, the edge closer to the respective clamping device in the assembly position in the (imaginary) one containing the sealing zone (15) Hollow cylinder lies (Fig. 3 and 4). 7. Pressure transducer according to one of claims 1 to 6, characterized in that one capsule part (8) is approximately U-shaped in cross section and the other capsule part (7), in particular connected to the displacement transducer (6), is approximately plate-shaped, preferably with one to the membrane projecting approach are formed and that the membrane (5) has a clamping flange (10) parallel and laterally offset to its membrane plane (M). 8. Pressure transducer according to claim 7, characterized in that that the in cross-section U-shaped capsule part (8) as a U-side leg has an outer, axially oriented, circumferential extension (21), on the end face, preferably on the inner edge, a Ring approach (22) with a narrow, z. B. about 0.5 mm wide circular ring surface as a sealing surface (23) in the Sealing zone (IS) is provided 9. Pressure transducer according to one of claims 1 to 8, characterized in that between the Membrane (5) and the capsule parts (7, 8) one "Self-sealing contact is provided and the contact surfaces are preferably polished surfaces exhibit. 10. Pressure transducer according to one of claims 1 to 9, characterized in that the area of the Contact surfaces in the sealing zone (15) with a thin metal layer, in particular from opposite the material of the capsule parts and / or the membrane is coated with softer metal, e.g. B. with tin, lead, aluminum, indium, gold, copper or the like 11. Pressure transducer according to one of claims 1 to 10, characterized in that as a seal between the membrane (5) and the capsule parts (7, 8) a layer of e.g. B. paint, plastic, rubber is provided 12. Pressure sensor according to one of claims 1 to 11, characterized in that in the separation area (24) a seal (25) is provided on the outside between the capsule parts (7, 8) 13. Pressure transducer according to one of claims 1 to 12, characterized in that the outer The edge-forming clamping flange (10) of the membrane (5) protrudes radially outward beyond the sealing area and is at least partially embedded in sealant 14. Pressure transducer according to claim 13, characterized in that one in the separation area of the capsule parts (7, 8) on the outside provided annular groove (26) for receiving the protruding edge of the membrane clamping flange (10) is provided, and that the groove (26) is preferably only partially covered with sealing compound is filled