SU659919A1 - Pressure differential pickup - Google Patents

Description

one

The invention relates to the field of instrumentation technology, namely to sensors for measuring pressure or differential pressure of liquid, gas and other mobile media.

Sensors are known for measuring the pressure difference, the principle of which is based on converting the pressure difference applied to the membrane to a change in the inductive coupling between the windings of the output differential transformer converter 1.

The closest technical solution to the invention is a sensor for determining the pressure difference, comprising a housing divided by a partition into two chambers, two fluid-filled and communicating membrane channels between each channel, each of which is located in a corresponding cavity, a differential transformer converter with a plunger connected to the rigid center of one of the membrane boxes 2.

Due to the fact that the plunger is in the zone of the controlled medium having different viscosities, the force of the direct action of the plunger on the membrane box is not the same for each medium. As a result, an extra gap in the measurement is introduced.

2

The presence of the plunger in a controlled environment, especially active, leads to its erosion, which leads to a change in the magnetic permeability of the plunger section -

converter. The reliability of the sensor drops sharply. Temperature stability of the sensor requires significant complications of its design. Also known are devices for measuring magnetic fields, including shielded magnetically controlled contacts included in a pavement measuring circuit, a voltage source and a recording device that provide high accuracy in measuring magnetic fields.

Claims (3)

In the proposed differential pressure sensor, comprising a housing divided into two chambers by a partition with a tube connecting the internal cavities of the membrane boxes placed in the chambers, in order to improve the measurement accuracy, the rigid centers of the membrane boxes are fastened together by a magnet symmetrically with respect to the poles on opposite Parts of the case are fixed with the possibility of movement along the magnet axis of the support with shielded magnetically controlled contacts included in the bridge measuring circuit. FIG. 1 schematically shows a differential pressure sensor, a general view; in fig. Figure 2 shows the electrical circuit for switching the magnetically controlled contacts; in fig. Fig. 3 shows a graph of stress versus pressure difference. The differential pressure sensor consists of a cornus 1 made of a non-magnetic material and divided by a hermetic partition 2 into two working chambers 3, a magnetic field source 4, such as a permanent magnet rigidly connected by poles with rigid centers of membrane boxes 5 and freely placed in the connecting duct 6 The housing is fixedly movable along the magnet axis of the support 7 with magnetic contacts 8, with a magnet shield 9. The measuring circuit includes magnetic contacts 8, in Bridge-connected, control resistors 10, current source 11 and voltage meter 12, the scale of which is calibrated in units of pressure difference. In the initial state, when the pressures in chambers 3 are equal (Pi Pz), the poles of source 4 of the magnetic field are at equal distances from the magnetically controlled contacts 8. At the same time, the forces of magnetic interaction in the working gaps of the magnetically controlled contacts 8 are equal, and therefore the gaps between the contact parts of the magnetically controlled contacts 8 are also equal. In the working gaps of the magnetic contacts 8 under the action of the current source 11, the current is excited and maintained with a current intensity measured in fractions of milliamperes. In this mode of operation, the voltage drop of the magnetically controlled contacts 8 depends on the size of the gaps between the contact parts, and in the initial state between points L and 5 of the measuring circuit (Fig. 2), the voltage meter 12 shows a zero potential difference, which corresponds to zero pressure differences in chambers 3. A zero potential difference is established by means of supports 7, which allow the distance between the magnetic contacts and the pole of the source 4 of the magnetic field to be adjusted. When a pressure difference occurs in the chambers, the rigid centers of the membrane boxes 5 move, and since they are rigidly attached to the source of a magnetic field, the latter will move to such a distance. Moving the source of the magnetic field 4 relative to the magnetically controlled contacts 8 causes 619 to change the magnetic interaction forces in their working gaps. In one, it decreases, and the contact parts are dispersed, forming a large working gap, and in the other, the working gap increases and decreases. With a slight change in the size of the working gaps, the voltage drop across the magnetically controlled contacts 8 changes dramatically. On the first, the voltage drop increases and on the second it decreases, which leads to imbalance in the bridge circuit. Between points A and B, a potential difference is formed, proportional to the pressure difference in KamSpax 3 sensors, which is recorded with high accuracy by a voltage meter 12. In the event of a change in the pressure setting in the sensor chambers 3, only the sign of the potential difference changes, and the needle of the voltage meter 12 is deflected in the opposite direction. Filling the membrane boxes 5 with gas ensures the constancy of the flux of the source 4 of the magnetic field in time due to the constant magnetic permeability of the medium. The pronounced dependence of the voltage change on the magnetically controlled contacts on the minor pressure changes in one of the chambers (Fig. 3) ensures high sensitivity and accuracy of the sensor. The invention The differential pressure sensor, comprising a housing divided into two chambers by a partition with a tube connecting the internal floors of membrane boxes placed in chambers, characterized in that, in order to improve measurement accuracy, the rigid centers of the membrane boxes are bonded to each other with a magnet symmetrically relative to the poles which on opposite parts of the case are fixed with the possibility of moving a support along the magnet axis with shielded magnetically controlled contacts included in the bridge measurement Yelnia scheme. Sources of information taken into account during the examination 1. Ageykin DI and others. Sensors of control and regulation. M., 1965, p. 595. 2. USSR author's certificate No. 524088, cl. G OIL 13/02, 1975. 3. USSR author's certificate No. 497539, cl. E 01R 33/00, 1974. 9 1-tL-X ten