PRESSURE MEASUREMENT DETECTOR FOR DETERMINING AND / OR MONITORING THE PRESSURE OF A VEHICLE

Abstract

Pressure measuring transducer for determining and / or monitoring a pressure of a medium, comprising: - a measuring mechanism (3) and a first pressure sensor (4) arranged in the measuring mechanism (3), which is subjected to the pressure of the medium (2) on a first surface (4a) and to a second pressure on a second surface (4b), - a separating membrane system (5) with a first separating membrane (6) and a second separating membrane (7), each of which has an axisymmetric deflection, on which a non-axisymmetric, in particular antisymmetric deflection is superimposed, in order to achieve a volume change in a pressure chamber.

Description

[0001] The invention relates to a pressure sensor for determining and / or monitoring the pressure of a medium.

[0002] In pressure measurement technology, absolute pressure, differential pressure, and gauge pressure sensors are known. Absolute pressure sensors measure the prevailing pressure absolutely, i.e., relative to a vacuum, while differential pressure sensors measure the difference between two different pressures. With gauge pressure sensors, the pressure to be measured is determined relative to a reference pressure, with the atmospheric pressure prevailing in the vicinity of the gauge pressure sensor serving as the reference pressure. A wide variety of such absolute pressure, differential pressure, and gauge pressure sensors are manufactured and distributed by companies in the Endress + Hauser Group.

[0003] Pressure transducers are used to measure pressure and / or to control, regulate, and / or automate a process within a plant. Pressure measuring devices are used in automation technology in a wide variety of industries, e.g., in the chemical and food industries, to name just a few important areas of application. Differential pressure measuring devices are used, in particular, for the continuous measurement of pressure differences in measuring media, e.g., in liquids, vapors, and gases. The differential pressure can be used, for example, to determine the fill level of a medium in a container or the flow rate of a measuring medium through a pipeline.

[0004] Pressure and differential pressure transducers have a pressure-sensitive element, a so-called pressure sensor, which is subjected to a first pressure and a second pressure on two opposite surfaces. The pressure of the medium is generally not in direct contact with the pressure sensor, but is recorded by one (in the case of the pressure transducer) and two (in the case of the differential pressure transducer) pressure-sensitive separating diaphragm(s) facing the process. Each separating diaphragm has an associated separating diaphragm bed, which serves to shape the separating diaphragm and to limit its displacement in the event of an overload. A diaphragm seal fluid is often used in addition, which transmits the pressure of the medium acting on the separating diaphragm to one of the two surfaces of the pressure sensor via a pressure transmission path.

[0005] If the separating diaphragm breaks or is damaged, the medium can penetrate the pressure or differential pressure sensor and contaminate and / or even damage it. To prevent this, it is common practice in the prior art to use a separating diaphragm system consisting of two parallel separating diaphragms, one of which faces the medium and the other faces the pressure fluid. A vacuum is provided between the two separating diaphragms. For such separating diaphragm systems consisting of two parallel separating diaphragms, it is common practice in the prior art to use so-called sinusoidal separating diaphragms. Sinusoidal separating diaphragms have a concentric embossed pattern whose cross-section resembles a sine wave.

[0006] The disadvantage of this is that when using two sinusoidal separation membranes for a separation membrane system, it can happen that in the event of a fault (damage or breakage) the two separation membranes do not separate from each other because they "stick" to each other due to their sinusoidal design and the parallel geometry.

[0007] Another disadvantage is that additional measures are required to evacuate the gap. For example, a circumferential annular channel running between the two separating membranes can be provided to evacuate air bubbles.

[0008] The invention is therefore based on the object of providing a remedy for this situation.

[0009] The object is achieved according to the invention by the pressure sensor according to patent claim 1.

[0010] The pressure sensor according to the invention for determining and / or monitoring the pressure of a medium comprises: a measuring mechanism and a first pressure sensor arranged in the measuring mechanism, which is subjected to the pressure of the medium on a first surface and to a second pressure on a second surface, a separating membrane system with a first separating membrane and a second separating membrane, which are arranged relative to one another such that the first separating membrane faces the medium and the second separating membrane faces away from the medium, and furthermore, a gap is enclosed between the first separating membrane and the second separating membrane, which gap is evacuated so that the gap has a vacuum, wherein the first and second separating membranes are attached to the measuring mechanism in a pressure-tight manner at a circumferential edge, forming a pressure chamber formed between the second separating membrane and the measuring mechanism, wherein the pressure of the medium is transmitted to the pressure chamber via the first separating membrane and the second separating membrane,wherein the pressure of the medium is transmitted via the pressure chamber to the first surface of the first pressure sensor, wherein the first and second separating membranes each have a deflectable, in particular different, working range and an embossed contour, wherein the pressure chamber is filled with a reference volume so that the first and second separating membranes form a reference position, wherein the first and second separating membranes are deflectable in both directions from the reference position so that the volume of the pressure chamber can be varied, and wherein the first and second separating membranes each have an axisymmetric deflection, on which a non-axisymmetric, in particular antisymmetric deflection is superimposed, to achieve the volume change in the pressure chamber.

[0011] The invention proposes the use of separating diaphragms for a double diaphragm system. Each of these diaphragms, due to the applied media pressure, performs an axisymmetric deflection superimposed on a non-axisymmetric deflection to achieve the volume change in the pressure chamber. This offers the advantage that, in the event of a defect, the two separating diaphragms separate more easily than is the case with two sinusoidal diaphragms, since the inner and outer diaphragms each strive to form their own bending line.

[0012] An advantageous embodiment of the pressure sensor according to the invention provides that the first and second separating membranes have different thicknesses.

[0013] A further advantageous embodiment of the pressure sensor according to the invention provides that the first and second separating membranes are designed in such a way that the intermediate space can be evacuated without an annular gap.

[0014] The invention is explained in more detail with reference to the following drawing. It shows: Fig. 1 : a schematic representation of a pressure sensor according to the invention.

[0015] In Fig. 11 shows a schematic representation of a pressure measuring transducer 1 according to the invention for determining and / or monitoring the pressure of a medium 2. A separating membrane system 5 is arranged facing the medium 2. The separating membrane system 5 has a first separating membrane 6 and a second separating membrane 7, which are connected to a measuring mechanism in a pressure-tight manner in the edge region. The first separating membrane 6 faces the medium 2, whereas the second separating membrane 7 faces away from the medium 2. Between the first separating membrane 6 and the second separating membrane 7, a vacuum is enclosed by the pressure-tight connection to the measuring mechanism. In the region of the second separating membrane 7, for example, a separating membrane bed 11 can be formed in the measuring mechanism 3.

[0016] Both separating diaphragms 6, 7 each have a different deflectable working range and an embossed contour and are connected to the measuring mechanism 3 at a circumferential edge, forming a pressure chamber 10. The pressure chamber 10 is filled with a reference volume, so that the first and second separating diaphragms 6, 7 form a reference position from which the two separating diaphragms 6, 7 can be deflected in both directions, so that a volume of the pressure chamber 10 can be varied. The first and second separating diaphragms 6, 7 are designed according to the invention such that, in order to achieve the volume change in the pressure chamber 10, they each have an axisymmetric deflection, on which a non-axisymmetric, in particular antisymmetric deflection is superimposed. In particular, the first and second separating diaphragms 6, 7 are designed according to the teaching of patent EP 2 300 739 B1, which patent is hereby incorporated by reference in its entirety.In particular, reference is made to the contents of paragraphs 25 to 81 of the description of patent EP 2 300 739 B1.

[0017] The pressure of the medium 2 is transmitted via the pressure chamber 10 and a first pressure transmission channel or path 9a to a first surface 4a of a pressure sensor 4 arranged in the measuring mechanism 3. The pressure sensor 4 is subjected to a second pressure on a second surface 4b opposite the first surface 4a. The pressure sensor 1 can be designed as a relative pressure sensor, which transmits an ambient pressure to the second surface 4b of the pressure sensor via a second pressure transmission channel or path 9b. Alternatively, the pressure sensor 1 can be designed as an absolute pressure sensor, in which case the second pressure is a vacuum. Furthermore, the pressure sensor can also be designed as a differential pressure sensor, in which case the second pressure is also in pressure-transmitting contact with the medium via a preferably identically designed separating diaphragm system.

[0018] The measurement signal of the pressure sensor 4 can, for example, be transmitted to an evaluation unit 12, which is designed to determine the pressure p of the medium 2 based on the measurement signal of the pressure sensor 4. List of reference symbols

[0019] 1Pressure transducer 2Medium 3Measuring element 4Pressure sensor 4aFirst surface of the pressure sensor 4bSecond surface of the pressure sensor 5Separation membrane system 6First separation membrane 7Second separation membrane 8Intermediate space 9aFirst pressure transmission path 9bSecond pressure transmission path 10Pressure chamber 11Membrane bed 12Evaluation unit

Claims

1. Pressure measuring transducer for determining and / or monitoring a pressure of a medium, comprising: - a measuring unit (3) and a first pressure sensor (4) arranged in the measuring unit (3), which is subjected to the pressure of the medium (2) on a first surface (4a) and to a second pressure on a second surface (4b), - a separating membrane system (5) with a first separating membrane (6) and a second separating membrane (7), which are arranged relative to one another in such a way that the first separating membrane (6) faces the medium (2) and the second separating membrane (7) faces away from the medium (2), and furthermore an intermediate space (8) is enclosed between the first separating membrane (6) and the second separating membrane (7), which intermediate space (8) is evacuated so that the intermediate space (8) has a vacuum, wherein the first and second separating membranes (6,7) are attached to the measuring mechanism (3) in a pressure-tight manner at a circumferential edge to form a pressure chamber (10) formed between the second separating membrane (7) and the measuring mechanism (3), wherein the pressure of the medium (2) is transmitted to the pressure chamber (10) via the first separating membrane (6) and the second separating membrane (7), wherein the pressure of the medium (2) is transmitted to the first surface (4a) of the first pressure sensor (4) via the pressure chamber (10), wherein the first and second separating membranes (6, 7) each have a deflectable, in particular different, working range and an embossed contour, wherein the pressure chamber (10) is filled with a reference volume, so that the first and second separating membranes (6, 7) form a reference position, wherein the first and second separating membranes (6, 7) are deflectable in both directions from the reference position, so that the volume of the pressure chamber (10) can be varied, and wherein the first and second separating membranes (6,7) each have an axisymmetric deflection, superimposed on a non-axisymmetric, especially antisymmetric deflection, to achieve the volume change in the pressure chamber.

2. Pressure sensor according to claim 1, wherein the first and second separating membranes (6, 7) have a different thickness.

3. Pressure sensor according to claim 1 or 2, wherein the first and second separating membranes (6, 7) are designed such that the intermediate space (8) can be evacuated without an annular gap.