Societe Nationale D'etude Et De Construction De Moteurs D'aviation

Snecma Propulsion Solide

Societe Nationale D'etude Et De Construction De Moteurs D'aviation-snecma

Societe Anonyme:societe Europeenne De Propulsion

Jean-Bernard Avisse

Jeanine Chiron

The pressure sensor () comprises a pressure detector element () arranged to receive a pressure that is to be measured and to detect it, and a printed circuit () connected to the pressure detector element () via an electrical connection, and it is characterized in that the electrical connection comprises at least one flexible conductive tongue () having a first end () connected directly or indirectly to the printed circuit () and a second end () merely bearing against a corresponding electrical contact () of the pressure detector element (). In order to ensure good electrical contact, the bearing face () of the second end of the or each flexible conductive tongue () bearing against the corresponding electrical contact () is polished.

Pressure sensor and a rocket engine incorporating it

In order to compensate non-linearity in the zero drift of the bridge at very low temperatures, a strain gauge in at least one of the arms of the bridge is in series with a resistor, e.g., a connection lead, of resistance that is much less than that of the strain gauge, and a compensation circuit is connected in parallel with the resistor. The compensation circuit includes a resistive element, e.g., a platinum probe, whose resistance varies as a function of temperature in such a manner as to influence, in the very low temperature range, the resistance of the parallel circuit of which it forms a part, and to do so in a manner that is sensitive to temperature and that increases with decreasing temperature.

Pressure sensor with compensation for null shift non-linearity at very low temperatures

Wheatstone bridge with temperature gradient compensation

The transducer has a primary winding wound around a first cylindrical support which delimits a passage where a core is axially movable, a first secondary winding wound around the primary winding and a second secondary winding wound on a second cylindrical support which surrounds completely the first secondary winding. The first secondary winding is formed in two portions: a regularly wound portion and a stepped portion which are phase connected, and the second secondary winding is formed in two similar portions which are antiphase connected. The output signals of the secondary windings are combined to obtain a differential signal representative of the ratio between the sum and the difference of said signals. The secondary windings are designated so that the ratio cannot reach the value +1 or -1 unless one secondary winding is cut-off, thus conferring to the transducer the capacity of being self-monitored. The separation between the secondary windings avoids any substantial capacitive coupling therebetween, and their mounting on separate supports makes it possible to vary their mutual axial position to adjust the response characteristics of the transducer.

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Castelneau de Medoc, France

Jean-Bernard Avisse