RU74466U1 - SENSOR - Google Patents

Abstract

The sensor is designed to measure a physical quantity, for example, overpressure, temperature or angle of inclination, and its conversion into a unified signal. The sensor contains the following main parts: a sensor element 1, housing 2, an electronic board 3, a casing 4, wires 8. A strain gauge is used as a sensitive element in gauges of excessive pressure, a thermoresistor in a temperature sensor, and a micro-accelerometer in an inclination sensor. The sensor 1 and the electronic board 3 are placed on the housing 2 using fasteners (stands, screws) and are closed by a casing 4. The terminals of the sensor 1 are connected to the electronic board 3. The terminals of the board 3 are connected to the wires 8. Insulation to prevent particles from entering the sensor oil, dust and moisture is provided by seals and sealant 6. The entire internal space of the sensor, limited by the housing 2 and the housing 4, is filled with epoxy compound 7. The technical results are vibration resistance, reliable connection elements, compact size of the sensor, as well as the susceptibility of the sensitive element to the influence of temperature error. 1 n and 3 z.p. f-ly, 3 ill.

Description

The inventive device is designed to measure a physical quantity, for example, overpressure, temperature or angle, and its conversion into a unified signal.

A device for measuring pressure is known (patent for the invention RU 2166741, IPC G01L 9/04, publ. 2001.05.10). It contains a housing with a fitting, a membrane connected by a rod with a middle part fixed to the base by the ends of an elastic beam. The elastic beam is made in the form of a rectangular parallelepiped, on the outer surface of which strain gages are placed. Through holes are made in the lateral faces of the elastic beam, perpendicular to its longitudinal axis and forming thickenings outside the zones of strain gauge placement. In addition, through the slots are made in the lateral faces of the elastic beam, parallel to the placement surfaces of the strain gages, forming a jumper and connecting the ends of the beams to each other. A through hole is made symmetrically with respect to the transverse axis of the beam in the central part of the bridge, the dimensions of which exceed the transverse dimensions of the rod. The stem is partially located in the hole of the jumper.

The disadvantage of this device is the fragility of the design, as well as the need for additional computing devices to convert the output signal.

Closest to the claimed sensor is a device for measuring temperature (patent for utility model RU 57896, IPC

G01K 7/16, publ. 2006.10.27), selected as a prototype. The device comprises a body with an external thread fixed in the pipeline using the installation head. The housing is closed at the top with a lid and connected at the bottom with a metal thermowell. A thermosensitive element, which is a quartz resonator, is fixed in the protective sleeve. The terminals of the heat-sensitive element through the wires are included in the signal converter circuit. The signal converter is made in the form of a frequency generator assembled on a printed circuit board, and placed in the housing. The installation head, housing and sleeve are made in the form of a functionally consistent solid, hollow inside a metal structure. In this case, the sleeve is made with a thermal resistance that is variable along its length - minimum at the place of removal of heat flux and maximum at the place of heat removal to the converter, and the printed circuit board with a quartz generator is placed under the cover and is separated from the body head by a non-metallic sleeve-glass.

The disadvantage of this device is the low vibration resistance, and therefore the impossibility of reliable operation of the device on vibrating objects.

The objective of the proposed solution is to create a sensor whose design would have high strength, compactness, resistance to vibration.

Technical results include vibration resistance, reliable connection of elements, compact size of the sensor, as well as the susceptibility of the sensitive element to the influence of temperature error.

The indicated technical results are achieved by implementing a set of essential features of the solution.

The sensor contains a housing, a casing, a sensing element, an electronic board, external terminals, fastening and insulation elements. The sensing element and the electronic board are electrically interconnected, placed on the housing and closed by a casing. In this case, the internal cavity of the sensor is filled with fillers.

In addition, additional solutions are declared that have the above set of features, while characterizing specific sensor designs.

In the overpressure sensor, a strain module is used as a sensitive element, while the fillers are made on the basis of an epoxy compound.

In the tilt sensor, a micro-accelerometer is used as a sensitive element, while the fillers are made on the basis of an epoxy compound.

In the temperature sensor, a thermistor is used as a sensitive element, while heat-conducting paste is used as a sealant around the thermistor, and the remaining cavity of the sensor is filled with fillers based on epoxy compound.

The sensor design in three functional versions is presented in the drawings: in Fig. 1, an overpressure sensor; in Fig. 2, an inclination sensor; and Fig. 3, a temperature sensor.

The positions in the drawings show:

1 - sensitive element;

2 - case;

3 - electronic board;

4 - a casing;

5 - heat insulating base;

6 - sealant;

7 - filler;

8 - wire.

The sensor contains the following main parts: sensor 1, housing 2, electronic circuit board 3, casing 4, wires 8.

A strain gauge is used as a sensitive element in gauges of excessive pressure, a thermistor in a temperature gauge, and a micro-accelerometer in a tilt gauge.

The sensor 1 and the electronic board 3 are placed on the housing 2 using fasteners (stands, screws) and are closed by a casing 4. The terminals of the sensor 1 are connected to the electronic board 3. The terminals of the board 3 are connected to the wires 8. Insulation to prevent particles from entering the sensor oil, dust and moisture is provided by gaskets and sealant 6.

The entire internal space of the sensor, limited by the housing 2 and the casing 4, is filled with an epoxy compound for reliable fixation of the sensor elements and impart vibration resistance to the sensor.

In the temperature sensor (FIG. 3), in addition, a heat-insulating base 5 is used for thermal insulation. Heat-conducting paste is used as sealant around the thermistor, and the remaining sensor cavities are filled with fillers based on epoxy compound.

The device operates as follows. Under normal conditions, at the outputs of the sensor 1 there is an initial voltage value supplied to the input of the electronic board 3. When the measured value changes, the value of the output voltage supplied to the input of the electronic board 3 changes.

In particular, in the overpressure sensor under normal conditions (atmospheric pressure at the sensor inlet), the bridge circuit on the basis of which the strain gauge module of the sensing element 1 is implemented is in a balanced state, i.e. from two of its outputs to the inputs of the electronic board 3 receives the same voltage. When the pressure changes from the side of the sensing element 1, an imbalance of the bridge circuit occurs, as a result of which a different voltage is supplied from the outputs of the sensing element 1 to the inputs of the board 3.

In the tilt sensor under normal conditions (the minimum measured tilt angle) at the outputs of the sensor 1, implemented on the basis of a micro-accelerometer, there is an initial voltage applied to the inputs of the board 3. When the position of the sensor 1 (and the sensor itself, since the sensor is changed) 1 is rigidly fixed to the sensor housing 2) in space (in the working plane), the value of the output voltages of the micro-accelerometer entering the inputs of the electronic board 3 changes.

In a temperature sensor under normal conditions (lower limit of the operating temperature range), the resistance of the thermistor, on the basis of which the sensitive element 1 is implemented, has a minimum value. The voltage drop across the thermistor is determined by measuring the voltage in the circuit before and after the resistance. These two values go to the inputs of the electronic board 3. When the temperature changes, the resistance value of the sensitive element 1 changes, which leads to a change in the voltage values supplied to the inputs of the board 3. In the electronic board 3, the two voltage values obtained from the sensor 1 are compared . The resulting voltage value, taking into account

the influence of the temperature error of the circuit elements on the sensor readings is converted into a unified signal - current consumption.

The entire sensor circuit included in the measuring circuit consumes 4 to 20 mA, depending on the measurement value (applied pressure, sensor angle or medium temperature).

Claims (4)

1. A sensor comprising a housing, a sensing element and an electronic board placed on the housing, electrically connected to each other and closed by a casing, external terminals, fastening and insulation elements, characterized in that the internal cavities of the sensor are filled with fillers. 2. The sensor according to claim 1, characterized in that a tensomodule is used as a sensitive element therein, while the fillers are made on the basis of an epoxy compound. 3. The sensor according to claim 1, characterized in that a microaccelerometer is used as a sensitive element therein, while the fillers are made on the basis of an epoxy compound. 4. The sensor according to claim 1, characterized in that a thermistor is used as a sensitive element, while heat-conducting paste is used as a sealant around the thermistor, and the remaining sensor cavities are filled with fillers based on epoxy compound.