Differential pressure measurement sensor assembly with overload protection

Abstract

This invention relates to a differential pressure measuring sensor (100) with overload protection, comprising: a measuring unit body (110); two separating diaphragms (130, 140); two overload diaphragms (150, 170) having radially variable material thickness h(r); a differential pressure transducer (190) for converting differential pressure into an electrical signal; and two hydraulic paths (200, 210); wherein each of the overload diaphragms (150, 170) is connected to the measuring unit body (110) to form an overload chamber; the separating diaphragms (130, 132) are connected to the measuring unit body (110) to form separating diaphragm chambers, and the overload diaphragm is enclosed in each of the separating diaphragm chambers. An overload diaphragm; each of the diaphragms (132) in the separation chamber is hydraulically connected to the overload chamber (152, 172) and to the differential pressure transducer (190) below the other separation diaphragm chamber via one of the hydraulic paths (200, 210), the hydraulic paths (200, 210) extending at least partially through the measuring unit body (110); and each of the overload diaphragms (150, 170) has a base surface (155, 175) facing a mating surface in the overload chamber (152, 172), in a standby state under equal pressure, the overload diaphragm (150, 170) is pre-tensioned against the mating surface.

Description

Technical Field

[0001] This invention relates to a differential pressure transducer assembly with overload protection. A typical differential pressure transducer generally includes a measuring element body having a first pressure input port and a second pressure input port. Hydraulic paths extend from each pressure input port to the differential pressure transducer to apply a first pressure and a second pressure, which the transducer measures the difference between. Typically, the differential pressure transducer has a deformable body, particularly a measuring diaphragm, on each side of which one of the two pressures can be applied, causing the measuring diaphragm to have elastic deformation depending on the difference between the two pressures. The pressure inlet ports of the measuring element body are typically closed by flexible metal separation diaphragms to form separation diaphragm chambers, each of which introduces pressure applied to the outside of the separation diaphragm into the chamber and the connected hydraulic paths. For measuring elements with coplanar pressure inlet ports, the pressure inlets are positioned adjacent to each other on the process connection surface of the measuring element body. For example, such measuring elements with coplanar pressure inputs are disclosed in EP 0370 013B1, EP 0560 875B1, EP0774 652B2, EP 1216 404B1, and WO 2014 / 095417 A1. Differential pressure cells are typically optimized to measure small pressure differences p1-p2 under large static pressures p1, p2. In doing so, it is important to find the correct balance between sensitivity and overload resistance. For example, the following can be applied to the measurement range of pressure difference |p1-p2|.

[0002] 2|p1-p2| / (p1+p2)<1%. Background Technology

[0003] If one of the pressures, p1 and p2, drops in the process facility, the load on the measuring sensor is 100 times its measuring range, which could damage the pressure transducer, hence the need for protection. Proven protection is based on a connected overload diaphragm that can deflect on both sides and is connected parallel to the measuring sensor. This overload diaphragm has a sufficiently large hydraulic capacity to absorb the volume of transferred fluid in the hydraulic path under unilateral overload to such an extent that the separating diaphragm of this hydraulic path contacts the diaphragm bed, thereby reliably preventing further increases in the differential pressure acting on the differential pressure sensor. Examples of differential pressure transducers with overload diaphragms acting on both sides are disclosed in EP 1 299 701 B1, DE 10 2006 040 325 A1, DE 102006 057 828 A1, WO 2014 / 095417A1, and US10,627,302B2.

[0004] As an alternative to an overload diaphragm that can deflect on both sides, two opposing prestressed overload diaphragms are described, each responding to a unilateral overload, as described in DD 279 065A1, DD 287 328A5, DD 290 716A5, DE32 22 620 A1, and US10,656,039B2. To reliably implement this principle, it must be ensured that the overload diaphragm deflects as much as possible only under pressure differentials outside the measurement range, where the required volumetric stroke of the overload diaphragm thus corresponds to the entire volume of the separation diaphragm chamber, where at most negligible plastic deformation may occur due to the required deflection. Furthermore, if all oil has already been drained from the high-pressure side separation diaphragm chamber, the overload diaphragm will be used to support the separation diaphragm in the event of a unilateral overload on the high-pressure side, in order to prevent plastic deformation of the separation diaphragm. Therefore, the profile of the overload diaphragm must correspond to the profile of the separation diaphragm, which is prepared, for example, by stamping an overload diaphragm blank with a die, as is possible with the overload diaphragm according to US10,656,039B2. According to US10,656,039B2, the resulting axial profile of the overload diaphragm should also have a greater axial travel than the coaxial profile on the surface of the measuring element body, with the overload diaphragm partially abutting the surface of the measuring element body. Firstly, this requires a very complex manufacturing process; secondly, the different requirements for the overload diaphragm are almost incompatible with each other, especially if the differential pressure transducer needs to be very compact, such that it is compatible with the coplanar process connection of the differential pressure transducer 3051 manufactured by Rosemount. Therefore, the object of the present invention is to provide a differential pressure transducer that provides reliable overload protection. According to the present invention, this object is achieved by the differential pressure transducer according to claim 1. Summary of the Invention

[0005] A differential pressure transducer assembly with overload protection according to the present invention includes: a measuring element body; a first separation diaphragm; a second separation diaphragm; a first overload diaphragm; a second overload diaphragm; a differential pressure transducer for converting differential pressure into an electrical signal; a first hydraulic path; and a second hydraulic path; wherein the first overload diaphragm is connected to the measuring element body to form a first overload chamber with a variable volume along the circumferential edge of the first overload diaphragm; wherein the second overload diaphragm is connected to the measuring element body to form a second overload chamber with a variable volume along the circumferential edge of the second overload diaphragm. An overload chamber; wherein the first separation diaphragm is connected to the measuring element body to form a first separation diaphragm chamber along the circumferential edge of the first separation diaphragm, wherein the first overload diaphragm is enclosed between the measuring element body and the first separation diaphragm; wherein the second separation diaphragm is connected to the measuring element body to form a second separation diaphragm chamber along the circumferential edge of the second separation diaphragm, wherein the second overload diaphragm is enclosed between the measuring element body and the second separation diaphragm; wherein the first separation diaphragm chamber is hydraulically connected to the second overload chamber via the first hydraulic path. The measuring element body has a first hydraulic path that extends at least partially through the first hydraulic path; wherein the second separation diaphragm chamber is hydraulically connected to the first overload chamber via the second hydraulic path, which extends at least partially through the measuring element body; wherein the differential pressure transducer is hydraulically connected to both the first and second separation diaphragm chambers; wherein the first overload diaphragm has a first base surface facing a first mating surface in the first overload chamber; wherein the second overload diaphragm has a second base surface facing a second mating surface in the second overload chamber; wherein the first overload diaphragm is prestressed against the first mating surface in an operable state of pressure equilibrium (i.e., zero differential pressure), such that the first base surface at least partially abuts the first mating surface; wherein the second overload diaphragm is prestressed against the second mating surface, such that the second base surface at least partially abuts the second mating surface; wherein the first overload diaphragm has a radially variable first material thickness h(r); and wherein the second overload diaphragm has a radially variable first material thickness h(r).

[0006] In a further development of the invention, the first overload diaphragm has a diaphragm bed facing the separating diaphragm, the diaphragm bed having a profile k(r) prepared by machining or forming. This type of preparation provides more degrees of freedom than the usual stamping of diaphragm blanks on a die, but by its very nature, the axial distance between local maxima and adjacent local minima is limited by the original thickness of the overload diaphragm material.

[0007] In a further development of the invention, the material thickness h(r) of the first overload diaphragm has a local maximum and a local minimum within the radial range 0 < r < 0.9R, wherein the difference between the local maximum and the local minimum of the material thickness of the overload diaphragm is not less than twice, in particular three times, the material thickness of the first separating diaphragm, and / or wherein the amount of the difference between the local maximum of the material thickness of the overload diaphragm and the material thickness of the overload diaphragm averaged over the radial range along the radius is not less than once the material thickness of the separating diaphragm, in particular not less than three and a half times the material thickness of the separating diaphragm.

[0008] In a further development of the invention, the material thickness h(r) of the overload diaphragm is not less than 4 times, in particular not less than 6 times, the local maximum.

[0009] In a further development of the invention, the first overload diaphragm has a first base surface facing the first mating surface and a first diaphragm bed surface facing the first separating diaphragm, wherein the first diaphragm bed surface has a first diaphragm bed profile with an axial coordinate of k(r) in order to support the first separating diaphragm in the case of unilateral overload, wherein, in the operable state in pressure equilibrium, i.e., with a pressure difference of zero, for the second derivative d 2 k / dr 2 of the axial coordinate k(r) of the first diaphragm bed profile according to the radius and for the second derivative d 2 h / dz 2 of the first material thickness h(r) of the first overload diaphragm according to the radius, the following applies:

[0010]

[0011] where g is a factor defining the integration limits, where 0.9 ≤ g ≤ 1, and where T is a dimensionless characteristic number not less than 0.9, in particular not less than 0.95.

[0012] In a further development of the invention, the first base surface has an axial coordinate b(r), wherein, in the operable state in pressure equilibrium, i.e., with a pressure difference of zero, for the second derivative d 2 b / dr 2 of the axial coordinate b(r) according to the radius, the following applies:

[0013]

[0014] where U is a dimensionless characteristic number not greater than 0.2, for example not greater than 0.1, in particular not greater than 0.05.

[0015] In a further development of the invention, the first overload diaphragm has a first central region (C), the outer radius r of which is not less than 30%, particularly not less than 40%, of the radius R of the overload diaphragm. The central region (C) is adjacent to a first transition region (B), which extends at a radius (R) of not less than 20%, for example, not less than 30%, of the radius (R) of the first overload diaphragm. Furthermore, in the unmounted equilibrium state of the first overload diaphragm, the axial coordinate of the base surface b(r) in the first transition region (B) has a larger average dimensionless slope R / h than that of the first central region. 最大 (B)·db(r) / dr, where h 最大 (B) is the maximum thickness of the overload diaphragm in the transition region (B).

[0016] In a further development of the invention, under the uninstalled equilibrium state of the first overload diaphragm, the dimensionless average slope R / h of the first transition region is determined using linear regression. 最 Large(B)·db(r) / dr is not less than 1.5, and in particular not less than 2.

[0017] In a further development of the invention, in the un-installed balanced state of the first overload diaphragm, the first transition region (B) has a truncated conical shape.

[0018] In a further development of the invention, the first edge region (A) is radially outwardly adjacent to the first transition region, wherein, in the unloaded equilibrium state of the first overload diaphragm, the average slope 1 / (hR)dz(r) / dr of the first edge region is not greater than one-quarter of the average slope of the transition region, for example, not greater than one-eighth.

[0019] In a further development of the invention, in the uninstalled state of the first overload diaphragm, the first base surface has a balanced shape with respect to the radius-related axial coordinate g(r), wherein there exists a balanced approximation function GN(r) determined by linear regression; wherein, in the installed and operable state of the overload diaphragm, the first base surface has a shape with respect to the radius-related axial coordinate b(r), wherein there exists an operating approximation function BN(r) determined by linear regression; wherein the slope of the operating approximation function BN(r) is not greater than three-quarters of the slope of the balanced approximation function GN(r), and in particular not greater than half.

[0020] In a further development of the invention, a differential pressure measurement range is specified for the differential pressure transducer, wherein the first overload diaphragm is prestressed against the mating surface to such an extent that, at a temperature of 300 K and a differential pressure corresponding to the maximum value of the differential pressure measurement range, the volumetric stroke of the first overload diaphragm corresponds to no more than 10%, particularly no more than 5%, of the oil volume contained in the second separation diaphragm chamber under pressure equilibrium and atmospheric pressure.

[0021] In a further development of the invention, the first overload diaphragm is made of steel, particularly cold-rolled steel of grade 1.4310 or 1.8159.

[0022] In a further development of the invention, the first overload diaphragm can be obtained by a method including tempering (i.e., annealing and quenching).

[0023] In a further development of the invention, the effective diameter of the first overload diaphragm is no greater than 27 mm, and particularly no greater than 25 mm. The effective diameter limits the deflectable range of the overload diaphragm. It is defined by the inner edge of the joint used to fasten the overload diaphragm to the mating body.

[0024] In a further development of the present invention, the second overload diaphragm is substantially the same in construction as the first overload diaphragm.

[0025] In a further development of the invention, each of the mating surfaces extends substantially parallel to the base surface of the overload diaphragm.

[0026] In a further development of the invention, in an operable state of pressure equilibrium, i.e. zero pressure difference, the volume enclosed between the mating surface and the base surface is no more than 20 μl in each case, and particularly no more than 10 μl.

[0027] In a further development of the invention, the measuring element body has a process connection surface having a first pressure port and a second pressure port, wherein the first separation diaphragm can be subjected to a first medium pressure through the first pressure port, and wherein the second separation diaphragm can be subjected to a second medium pressure through the second pressure port, and wherein the two separation diaphragms are arranged in a manner coplanar with respect to each other.

[0028] In a further development of the invention, the measuring element body has a first diaphragm support surface and a second diaphragm support surface, wherein a first separating diaphragm is arranged on the first diaphragm support surface and a second separating diaphragm 240 is arranged on the second diaphragm support surface, wherein the two diaphragm support surfaces are back to back. Attached Figure Description

[0029] The invention will now be explained in more detail with reference to exemplary embodiments shown in the accompanying drawings. In the drawings:

[0030] Figure 1 A schematic diagram illustrating the operating principle of the differential pressure transducer according to the present invention is shown;

[0031] Figure 2a The longitudinal section of the overloaded diaphragm in the equilibrium position is shown;

[0032] Figure 2b The longitudinal section of the overload diaphragm positioned above the mating body in the equilibrium position is shown.

[0033] Figure 2c The longitudinal cross-sections of the separation diaphragm chamber and the overload chamber are shown in an operational state under pressure equilibrium, i.e., zero differential pressure.

[0034] Figure 2d The longitudinal sections of the separation diaphragm chamber and the overload chamber under overload conditions are shown;

[0035] Figure 3a A graph showing the volumetric travel of the overload diaphragm as a function of the pressure difference across the two sides of the overload diaphragm is presented.

[0036] Figure 3b A graph showing the maximum mechanical stress of the overload diaphragm as a function of the pressure difference across the two sides of the overload diaphragm is presented. Detailed Implementation

[0037] Figure 1 The schematic diagram illustrates how various components of an exemplary embodiment of the transducer according to the invention are hydraulically coupled to produce its effect. The differential pressure transducer assembly 100 has a metallic measuring element body 110, to which a first separation diaphragm 130 and a second separation diaphragm 140 are attached via circumferential joints to form first and second separation diaphragm chambers 132, 142, respectively. First and second overload diaphragms 150, 170 are respectively arranged within the respective separation diaphragm chambers 132, 142, wherein the first and second overload diaphragms 150, 170 are fastened to the measuring element body 110 via circumferential joints to form first and second overload chambers 152, 172, respectively. The two separation diaphragms 130, 140 are made of steel, particularly stainless steel or spring steel with a material thickness of less than 100 μm, such as 30 μm, wherein a contour is embossed on the diaphragms to improve the linearity of the relationship between the pressure difference between the two separation diaphragms and the resulting volumetric stroke of the separation diaphragms. The diameter of the separation diaphragms can be, for example, 25 to 30 mm. As a result, the separating membrane is very flexible and can deflect to both sides under small pressure differentials (depending on the sign of the pressure differential).

[0038] The diameters of the two overload diaphragms 150 and 170 are slightly smaller than those of the separation diaphragms 130 and 140, with the effective diameters typically ranging from 22 mm to 26 mm. They also have a larger initial material thickness, depending on the measurement range, for example, 200 to 1000 μm, and in this example, 700 μm, making the overload diaphragms 150 and 170 many times harder than the separation diaphragms 130 and 140, particularly more than 1000 times harder. Furthermore, the overload diaphragms 150 and 170 are prestressed against the measuring element body 110, making initial deflection towards the measuring element body 110 impossible, and secondly, deflection away from the measuring element body 110 only occurs after the pressure difference between the overload chamber and the adjacent separation diaphragm chamber is sufficient to overcome the prestress on the overload diaphragms. Overload membranes 150 and 170 each have a wavy membrane bed on the side facing separation membranes 130 and 140, respectively, to support separation membranes 130 and 140 under overload conditions.

[0039] The separation diaphragm chambers 130, 140 and the overload chambers 152, 172 are connected by hydraulic paths as shown below. Starting from the first separation diaphragm chamber 132, a first hydraulic path 200, which at least partially includes an aperture in the measuring element body 110, extends to the second overload chamber 172. Correspondingly, a second hydraulic path 210, which at least partially includes an aperture in the measuring element body 110, extends to the second overload chamber 172. Correspondingly, the second hydraulic path 210 extends from the second separation diaphragm chamber 142 to the first overload chamber 152.

[0040] The differential pressure transducer assembly 100 also includes a differential pressure transducer 190, such as a (piezoelectric) resistance transducer or a capacitive transducer, which is connected to a first hydraulic path via first and second capillary lines 202, 212 leading to two hydraulic paths 202, 212, in order to record the pressure difference between the two hydraulic paths and provide a main electrical signal representing the pressure difference.

[0041] For the differential pressure transducer 190, a measurement range is defined, which is typically smaller than the maximum differential pressure that the transducer 190 can withstand. The prestressing of the overload diaphragms 150 and 170 is chosen such that they undergo only negligible deflection under differential pressure within the measurement range. However, if the differential pressure exceeds the measurement range, the deflection of the overload diaphragm on the lower pressure side begins to absorb the volume of transferred fluid in the separation diaphragm chamber on the high-pressure side, causing the separation diaphragm on the high-pressure side to contact the diaphragm bed on the high-pressure side, thereby preventing further increase in the differential pressure at the transducer. Therefore, the overload diaphragms are sized such that this state occurs before the strength limit of the differential pressure transducer is reached.

[0042] In the accompanying drawings, separation diaphragms 130 and 140 and overload diaphragms 150 and 170 are represented by arcs. This illustration is not related to their actual shapes, because… Figure 1 This only concerns the functional arrangement of the components of the differential pressure transducer relative to each other.

[0043] Figures 2a to 2d Exemplary embodiments of the overload diaphragm 150 of the differential pressure transducer according to the present invention are shown in various installation and operating conditions. Figure 2a In the diagram, the free overload diaphragm 150 is shown as being in equilibrium, i.e., without external forces or torques. The overload diaphragm is substantially rotationally symmetric about the Z-axis. It has a radius R between 11 mm and 14 mm and a maximum material thickness h between 0.6 mm and 0.8 mm. 最大 The overload diaphragm 150 has a planar central region C and a planar edge region A, wherein a transition region B (partially a truncated cone-shaped transition region B) extends between the two. Therefore, the overload diaphragm 150 has a base surface 150, the axial coordinate b(r) of which is constant, for example, zero, in the central region under equilibrium conditions, and increases uniformly in the transition region B to the maximum material thickness h of the overload diaphragm 150. 最大 Approximately 60% to 80% of the value of b(r). Such a value of b(r) is then constant in the edge region A, and therefore also corresponds to the value of b(R) at radius R. The transition region B has a radius of R. k Initially, the radius R k It is approximately half the radius R. The upper side of the overload diaphragm, facing away from the base surface 155, has a diaphragm bed with a (here, a wave-like) profile k(r), which is formed by machining or shaping. The depth of the profile here reaches slightly greater than the maximum material thickness h of the overload diaphragm 150. 最大 Half of that. Therefore, the minimum material thickness h of the overload diaphragm 150. 最小 Slightly smaller than the maximum material thickness. The material thickness h(r), as a function of radius, is generated by the difference between the profile k(r) and the axial coordinates of the base surface b(r), i.e., h(r) = k(r) - b(r). It can be seen that the material thickness h(r) is affected by the profile k(r) and, in practice, is not affected by b(r). In principle, the elastic properties of the diaphragm are therefore specified by the course of the coordinates b(r) of the base surface, where the profile k(r), designed independently of this, is used on the one hand to form the diaphragm bed and on the other hand to model the stress and stiffness of the overloaded diaphragm.

[0044] Figure 2bAn overload diaphragm 150 is shown on the mating surface 115 of the measuring element body 110. Here, it is particularly important that the mating surface is not planar, but rather has a maximum value at the center and slopes outwards. If the overload diaphragm 150 rests on the base of the planar surface and is clamped against the base of the planar surface in the edge region, this orientation of the mating surface roughly corresponds to the curvature of the overload diaphragm 150. In fact, the pressure is only applied within the radius R. k The force acts on the base. If the center of the mating surface 115 therefore happens to follow the curvature of the base surface during the aforementioned deformation, the overloaded diaphragm is not yet supported. Only a further increase at the center of the mating surface 115 releases the radius R. k The nearby overload diaphragm. Regardless of whether this release is desired, it is desirable that the mating surface 115 approximate the bend line b(r) in order to minimize the amount of transferred fluid in the overload chamber. The mating surface 115 is designed with these considerations in mind.

[0045] Figure 2c A cross-section of the differential pressure transducer assembly (100) according to the invention is shown in a ready-to-operate state under pressure equilibrium. An overload diaphragm 150 is stretched over a mating surface 115 formed according to the above considerations and fastened to the measuring element body 100 by a circumferential weld 154 in its edge region, such that an overload chamber 152 is formed between the overload diaphragm 150 and the measuring element body 100. However, under pressure equilibrium, the overload chamber 152 is compressed to a remaining volume (not shown) by prestressing the overload diaphragm 150. A separation diaphragm 130 is arranged above the overload diaphragm 150 and is fixed to the measuring element body 110 by a circumferential weld 134, wherein a separation diaphragm chamber 132 is formed between the measuring element body 110 and the separation diaphragm 130. The separation diaphragm 130 is pressed onto the diaphragm bed 153 of the overload diaphragm. The separating diaphragm chamber 132 is filled with hydraulic transfer fluid and is connected to the second overload chamber 172 via a first hydraulic path 210. The second overload chamber 172 is structurally identical to the first overload chamber 152. The first overload chamber 152 is connected to the second separating diaphragm chamber 142 via a second hydraulic path 212. The second separating diaphragm chamber 142 is structurally identical to the first separating diaphragm chamber 132.

[0046] at last, Figure 2d The diagram illustrates an overload event that occurs when the pressure difference between the second separation diaphragm chamber 142 or the second hydraulic path 212 and the pressure in the first separation diaphragm chamber 132 exceeds a limit value outside the measurement range specified for the differential pressure transducer. In this case, the first overload diaphragm deflects and absorbs a certain volume of transferred fluid discharged from the second separation diaphragm chamber 142, causing the second separation diaphragm to come into contact with the second overload diaphragm.

[0047] To facilitate reliable deflection of the overload diaphragm 150, it is advantageous if the mating surface 115 only approximately follows the curvature of the base surface 155 under pressure equilibrium, so that any remaining transfer fluid remains in the overload chamber 152 to transmit pressure to the overload diaphragm 150. For support, channels in the form of grooves can be formed in the mating surface and / or the base surface to facilitate the distribution of transfer fluid beneath the overload diaphragm.

[0048] Figure 3a and Figure 3b The diagram in the image shows the target from Figures 2a to 2d The results of FEM calculations for the overload diaphragm. Therefore, the overload diaphragm is characterized by spring steel grade 1.8159, which has an experimentally determined elastic modulus of 195 GPa and an R0 of 1.3 GPa. p02 Starting material thickness h 最大 The diameter of the overload diaphragm was set to 700 μm and the effective diameter of the overload diaphragm was set to 23.6 mm. Figure 3a The volumetric stroke of the overload diaphragm as a function of the differential pressure between its two sides is shown. Therefore, the volumetric stroke is practically negligible up to approximately 1.8 MPa of differential pressure, then increases abruptly under overload conditions, reaching approximately 55 μl at approximately 3.9 MPa. This is sufficient to absorb the entire volume of transfer fluid from the separation diaphragm chamber connected to the overload chamber, thus preventing further increases in differential pressure and protecting the differential pressure transducer. It has been shown that it is advantageous to apply this unilateral overload pressure to the overload diaphragm once before the differential pressure transducer enters operation, for example, when the measuring element is filled with transfer fluid, to produce the maximum desired volumetric stroke. This results in a slight modification to the characteristic curve of the volumetric stroke as a function of differential pressure. Consequently, the overload diaphragm undergoes slight plastic deformation. Figure 3a The solid characteristic curve in the figure represents this first deflection of the overloaded diaphragm, while the dashed characteristic curve applies to all further deflections. The effect of this first deflection is... Figure 3b It is clearly shown in the text, Figure 3b The FEM calculation results for the maximum Von Mises stress in the overloaded diaphragm as a function of differential pressure are shown. Conversely, solid lines apply to the first deflection of the overloaded diaphragm, while dashed lines describe all further deflections. At the first deflection, the peak stress of the overloaded diaphragm material can be seen exceeding R. p02 This results in minimal plastic deformation of the overloaded diaphragm during initial deflection. However, under repeated deflection, the stress peaks are largely eliminated, which is why a constant relationship between volumetric stroke and differential pressure is achieved. This allows for reliable protection of the differential pressure transducer from overload on one side.

Claims

1. A differential pressure transducer assembly (100) with overload protection, comprising: Measuring element body (110); First separation membrane (130); Second separation membrane (140); First overload diaphragm (150); Second overload diaphragm (170); Differential pressure transducer (190), the differential pressure transducer (190) is used to convert differential pressure into an electrical signal; First hydraulic path (200); and second hydraulic path (210); The first overload diaphragm (150) is connected to the measuring element body (110) to form a first overload chamber (152) with a variable volume along the circumferential edge (154) of the first overload diaphragm. The second overload diaphragm (170) is connected to the measuring element body (110) to form a second overload chamber (172) with a variable volume along the circumferential edge (174) of the second overload diaphragm. The first separation membrane (130) is connected to the measuring element body (110) to form a first separation membrane chamber (132) along the circumferential edge (134) of the first separation membrane. The first overload diaphragm (150) is enclosed between the measuring element body (110) and the first separation diaphragm (130); The second separation membrane (140) is connected to the measuring element body (110) to form a second separation membrane chamber (142) along the circumferential edge (144) of the second separation membrane. The second overload diaphragm (170) is enclosed between the measuring element body (110) and the second separation diaphragm (140); The first separation diaphragm chamber (132) is hydraulically connected to the second overload chamber (172) via the first hydraulic path (200), which at least partially extends through the measuring element body (110). The second separation diaphragm chamber (142) is hydraulically connected to the first overload chamber (152) via the second hydraulic path (210), which at least partially extends through the measuring element body (110). The differential pressure transducer (190) is hydraulically connected to the first separation membrane chamber (132) and the second separation membrane chamber (142). The first overload diaphragm (150) has a first base surface (155) facing the first mating surface (115) in the first overload chamber (152). The second overload diaphragm (170) has a second base surface (175) facing the second mating surface (117) in the second overload chamber (172). The first overload diaphragm (150) is prestressed against the first mating surface (115) in an operable state of pressure balance, i.e. zero pressure difference, so that the first base surface (155) at least partially abuts against the first mating surface (115). The second overload diaphragm (170) is prestressed against the second mating surface (117), such that the second base surface (175) at least partially abuts against the second mating surface (117). Wherein, the first overload diaphragm (150) has a radially variable first material thickness h(r); and The second overload diaphragm (170) has a radially variable first material thickness h(r).

2. The differential pressure transducer assembly (100) according to claim 1, wherein, The first overload diaphragm has a diaphragm bed surface (153) facing the separation diaphragm, the diaphragm bed surface (153) having a profile k(r) prepared by machining or forming.

3. The differential pressure transducer assembly (100) according to claim 1 or 2, wherein, The material thickness h(r) of the first overload diaphragm (150) has a local extremum in the radial range 0 < r < 0.9 R, where R is the radius of the first overload diaphragm in the unequipped state and r is the radius at which the local extremum is located. The difference between the local maximum and local minimum of the material thickness of the first overload diaphragm (150) is not less than twice the material thickness of the first separation diaphragm (130), and / or, the difference between the local maximum of the material thickness of the first overload diaphragm (150) and the average material thickness of the first overload diaphragm in the radial range along the radius is not less than once the material thickness of the first separation diaphragm.

4. The differential pressure transducer assembly (100) according to claim 3, wherein, The difference between the local maximum and local minimum values ​​of the material thickness of the first overload diaphragm (150) is not less than three times the material thickness of the first separation diaphragm (130), and / or, wherein the difference between the local maximum value of the material thickness of the first overload diaphragm and the average material thickness of the first overload diaphragm over the radial range along the radius is not less than three and a half times the material thickness of the first separation diaphragm.

5. The differential pressure transducer assembly (100) according to claim 3, wherein, The material thickness h(r) of the first overload diaphragm (150) is not less than 4 times the local maximum value.

6. The differential pressure transducer assembly (100) according to claim 3, wherein, The material thickness h(r) of the first overload diaphragm is not less than 6 times the local maximum value.

7. The differential pressure transducer assembly (100) according to claim 3, wherein, The first overload diaphragm (150) has a first base surface (155) facing the first mating surface (115) and a first diaphragm bed surface facing the first separating diaphragm, wherein the first diaphragm bed surface has a first diaphragm bed profile with an axial coordinate of k(r) to support the first separating diaphragm under unilateral overload, wherein, in an operable state of pressure equilibrium, i.e., zero pressure difference, the second derivative d with respect to the radius of the axial coordinate k(r) of the first diaphragm bed profile... 2 k / dr 2 and the second derivative d with respect to the radius of the first material thickness h(r) of the first overload diaphragm. 2 h / dr 2 The following applies: Where g is a factor that limits the integral, where 0.9 ≤ g ≤ 1, and T is a dimensionless characteristic number not less than 0.

9.

8. The differential pressure transducer assembly (100) according to claim 7, wherein, T is a dimensionless characteristic number of not less than 0.

95.

9. The differential pressure transducer assembly (100) according to claim 7, wherein, The first base surface (155) has an axial coordinate b(r), wherein, when the first overload diaphragm abuts against the first mating surface, the second derivative d of the axial coordinate b(r) with respect to the radius of the first base surface is... 2 b / dr 2 And the second derivative d with respect to the radius of the first material thickness h(r) of the first overload diaphragm. 2 h / dr 2 The following applies: Where U is a dimensionless characteristic number not greater than 0.

1.

10. The differential pressure transducer assembly (100) according to claim 9, wherein, U is a dimensionless characteristic number not greater than 0.

05.

11. The differential pressure transducer assembly (100) according to claim 3, wherein, The first overload diaphragm (150) has a first central region (C), the outer radius r of which is not less than 30% of the radius R of the first overload diaphragm (150), wherein the central region (C) is adjacent to a first transition region (B), which extends over a radius (R) of not less than 20% of the first overload diaphragm (150), wherein in the uninstalled balanced state of the first overload diaphragm (150), the axial coordinate b(r) of the first base surface in the first transition region (B) has a larger average dimensionless slope R / h than that of the first central region. 最大 (B) db(r) / dr, where h 最大 (B) is the maximum thickness of the first overload diaphragm in the transition region (B).

12. The differential pressure transducer assembly (100) according to claim 11, wherein, The outer radius r of the first central region (C) is not less than 40% of the radius R of the first overload diaphragm, wherein the first transition region (B) extends over a radius (R) of the first overload diaphragm (150) of not less than 30%.

13. The differential pressure transducer assembly (100) according to claim 11, wherein, The dimensionless average slope R / h of the first transition region, determined by linear regression, under the uninstalled equilibrium state of the first overload diaphragm (150). 最大 (B) db(r) / dr is not less than 1.

5.

14. The differential pressure transducer assembly (100) according to claim 11, wherein, The dimensionless average slope R / h of the first transition region, determined by linear regression, under the uninstalled equilibrium state of the first overload diaphragm (150). 最大 (B) db(r) / dr is not less than 2.

15. The differential pressure transducer assembly (100) according to claim 11, wherein, In the unloaded balanced state of the first overload diaphragm (150), the first transition region (B) has a truncated conical shape.

16. The differential pressure transducer assembly (100) according to claim 11, wherein, The first edge region (A) is radially outwardly adjacent to the first transition region, where z(r) represents the axial displacement function of the first overload diaphragm in the radial direction r in the uninstalled equilibrium state, wherein in the uninstalled equilibrium state of the first overload diaphragm (150), the average slope 1 / (h R) dz(r) / dr of the first edge region is not greater than one-quarter of the average slope of the transition region.

17. The differential pressure transducer assembly (100) according to claim 16, wherein, In the unloaded equilibrium state of the first overload diaphragm (150), the average slope 1 / (h R) dz(r) / dr of the first edge region is not greater than one-eighth of the average slope of the transition region.

18. The differential pressure transducer assembly (100) according to claim 1 or 2, wherein, In the uninstalled state of the first overload diaphragm (150), the first base surface (155) has a balanced shape with respect to the radius-dependent axial coordinate g(r), wherein there exists a balanced approximation function GN(r) determined by linear regression; In the operable state where the first overload diaphragm (150) is installed, the first base surface (155) has a shape with respect to the radius-dependent axial coordinate b(r), wherein there exists an operating approximation function BN(r) determined by linear regression. Wherein, the slope of the operation approximation function BN(r) is no greater than three-quarters of the slope of the equilibrium approximation function GN(r).

19. The differential pressure transducer assembly (100) according to claim 18, wherein, The slope of the operational approximation function BN(r) is no greater than half the slope of the equilibrium approximation function GN(r).

20. The differential pressure transducer assembly (100) according to claim 1 or 2, wherein, A differential pressure measurement range is specified for the differential pressure transducer, wherein the first overload diaphragm is prestressed against the first mating surface to such an extent that, at a temperature of 300 K and a differential pressure corresponding to the maximum value of the differential pressure measurement range, the volumetric stroke of the first overload diaphragm corresponds to no more than 10% of the oil volume contained in the second separation diaphragm chamber under pressure equilibrium and atmospheric pressure.

21. The differential pressure transducer assembly (100) according to claim 20, wherein, The first overload diaphragm is prestressed against the first mating surface to such an extent that, at a temperature of 300 K and a differential pressure corresponding to the maximum value of the differential pressure measurement range, the volumetric stroke of the first overload diaphragm corresponds to no more than 5% of the oil volume contained in the second separation diaphragm chamber under pressure equilibrium and normal pressure.

22. The differential pressure transducer assembly (100) according to claim 1 or 2, wherein, The first overload diaphragm is made of steel.

23. The differential pressure transducer assembly (100) according to claim 22, wherein, The steel is cold-rolled steel with grade 1.4310 or 1.8159.

24. The differential pressure transducer assembly (100) according to claim 1 or 2, wherein, The first overload diaphragm has been tempered.

25. The differential pressure transducer assembly (100) according to claim 1 or 2, wherein, The second overload diaphragm (170) is constructed in the same way as the first overload diaphragm (150).

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