SU433694A3 - - Google Patents

Description

one

The invention relates to shaped metal membranes for linear pressure measurement using piezo-resistivity. These measurements can be carried out both by the E conditions of atmospheric pressure and under static pressure conditions (measurement of pressure difference).

Flat metal membranes with strain gauge converters are known. Under pressure, areas with positive and negative is elongations form on the surface of such a membrane. Various strain gauge transducers of both regions are connected to a membrane in a half bridge circuit or a full bridge circuit. Such bridge circuits 20 provide a measuring voltage dependent on the pressure and on the applied supply voltage. However, the proportionality between pressure and measuring pressure - 26

Only about 10 kg / cm is achieved.

If the size of the same membrane is chosen with the calculation of its use for measuring a pressure of less than 10 kg / cm, then a very large deviation from linearity is observed, since, due to the increasing relative deformation of the membrane, an additional tension is superimposed on the bending stress.

In order to avoid such phenomena when measuring low pressures, strain gauges are provided not on the membrane itself, but on the carrier associated with it. In this case, the membrane itself serves only to create an effort, and the transfer of this effort is carried out by the carrier.

However, such devices are structurally complex and cumbersome.

Also known membranes in which completely abandoned

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nobitele b

Wuxi and S are created by a membrane that are directly transferred to free-tensioned windows that have EDGEDT as piezoelectricity.

However, the cost of manufacturing such electrodes is very high.

The purpose of the invention is to improve the accuracy when measuring small se masks of pressure

 This marginal Won of the membrane (TO 8, uchasz-ok membranes are Neighborhood bordering the buildings) is completely flat and spread out in one plane on the profile part of the metal wall. “At the marginal zone you will apply piezoelectric layers. The piezoelectric layer prepares to go to the surface. and in the original layer. This ensures current flow mainly in the direction of radial expansion.

Piezoelectric layers can be placed both on the top: and on the lower side of the edge zone of the membrane. They can be divided into separate sections (for example, on the downward side two sections), which allows you to build a full bridge circuit

Further, for example, predominantly, when measuring the pressure drop under conditions of high ambient values of the gaps of the side of the membrane, the layers applied by the piezoelectrically can be placed in a protective

LIQUID.

The technical and economic advantages of the invention are laid with a simple and durable membrane design and piezoresistance with good linear pressure and a corresponding outgoing electrical signal.

In addition, additional carriers are required for strain gauge transducers or carrier elements to accommodate free-tension wires that perform electrical measurements of elongations. Structural strength is ensured by the fact that the corresponding layers are applied rather than glued, which, in turn, avoids losses due to surface leakage current. Into nonshaw layers be very thin, which guarantees a good heat dissipation from the conductor material. Radially directed positive + negative gi -

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successively on the upper and lower sides of the surface, the edge zone of the membrane is optimally transferred to the conductive layer. The small thickness and the meander structure create conditions for relatively high internal resistance, which provides the measuring electrode. The electrical load on the applied conductive layer can be maintained at a given level due to high; Internal 1) relatively high supply voltages may be applied.

The applied conductive layers could be subjected to high absolute pressures.

Fig, I shows the profile of the proposed membrane; 2 conductive layers on the edge of the membrane; in fig. 3 - wire of the 1st layer with insulating and protective layers; in fig. 4 - conductive layers, divided into separate areas,

The preformed metal membrane I is clamped by two parts 2 and 3 of the body. The membrane profiling reaches the flat marginal zone 4, the middle plane of which is identical to the middle plane 5 of the membrane. Under these conditions, a profile of a special 5 form is not required: only the height of the profile is important. The marginal zone 4 is provided for relatively narrow iodine pressure on the profiled membrane resulting in deformation of the median plane of the 5J torus leads to the formation of a relatively small radius of curvature of the marginal zone, due to which high elongation values are achieved with very small deviations from linearity. Membrane profiling prevents the formation of tensile stresses, which is important for reducing deviations from linearity.

The conductive layer, fig. 2) is placed on the marginal zone 4. The ends of this layer are in contact with the membrane at locations 7, and the electrical conductors through the insulating, pressure-tight, inlets are removed from the housing. :

Fig. 3 shows a design of a conductive layer 6, which is piezo-resistive. On the marginal zone 4 of the membrane I, on one or both sides, thin insulating LAYER 8 is applied first and behind;

The thin conductive layer 6 can be further applied. A protective layer 9 can be applied from above to protect the conductive layer.

i

FIG. 4, the mWaid arrangement of the layer 6 has been proved, which serve to obtain high resistance.

PREVENTION OF THE INVENTION 11PROFESSED Metallic, middle and edge zone membrane, which is covered with a piezo-resistive layer of semiconductor film, characterized in that, in order to improve accuracy when measuring small values of pressure, the edge zone is made completely flat and is in the same plane with the core part .

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