RU2548404C1 - Method to measure difference of pressures by sensor with frequency modulated output signal and sensor for realisation of method - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: invention relates to instrument making, may be used independently or within measurement and computing complexes and control systems. The method to measure difference of pressures by a sensor with a frequency-modulated output signal consists in the fact that they use two identical membranes with resonators grown on them epitaxially, separated by a vacuumised gap. A sensor for measurement of pressure difference with a frequency modulated output signal comprises a hollow body, two identical membranes with epitaxially grown resonators, a system of resonator oscillations excitation with a permanent magnet and a system of generation of an output signal separated by a vacuumised gap.

EFFECT: simplified design of a sensor and its improved manufacturability.

2 cl, 3 dwg

Description

The invention relates to instrumentation, can be used independently or as part of measuring and computing systems and control systems operating in a wide range of mechanical and thermal influences and designed to obtain information about the pressure difference of the studied liquid and gaseous media.

The invention can be used in measuring and computing systems for transporting liquids, gases, in fuel supply systems, in internal combustion engines, steam and gas turbines, utility networks for various purposes, in household appliances.

A known method of measuring the pressure difference by sensors with a frequency-modulated output signal. Silicon resonators have the same shape, size and identical mechanical characteristics, are grown epitaxially on the working surfaces of the membranes.

Known US patent No. 4841775 [1] containing a differential pressure sensor, made in the form of a single silicon crystal, including a diode and a transistor.

A known method of measuring the pressure difference with a frequency-modulated output signal (patent EPO 456029 A1) [2], which use a membrane with epitaxially grown resonators on it, excite oscillations of the resonators and generate an output signal.

Also known is a micromechanical pressure sensor with a frequency-modulated output signal according to the aforementioned patent [2], comprising a housing, a silicon membrane with resonators epitaxially grown on it in a single technological process and their capsules evacuating them to ensure a sufficiently high level of quality factor of a mechanical oscillating system, an oscillation excitation system with a permanent magnet, a system for generating an output signal.

This sensor has sufficiently high metrological characteristics, since the membrane, resonators and capsule are fragments of a single crystal and are made without the use of bonding by epitaxial growth and selective etching. The solution for this patent is selected as the closest analogue.

However, the complexity of the manufacturing process of the “resonator-capsule” pair and the evacuation of the space inside the capsule makes the method and design of the closest analogue not technologically advanced, since the process used is one of the most complex among the microsystems used in the technology.

The proposed method and design of the sensor does not require the use of vacuum capsules, as in the prototype, which greatly simplifies the design and makes it much more technological while maintaining high metrological characteristics and quality factor of the resonator.

The specified technical result is achieved by the fact that the proposed method and the sensor with a frequency-modulated output signal in the hollow housing contains a sensitive element - two silicon single crystal membranes with secondary measuring elements epitaxially grown on it - resonators separated by a vacuum gap, providing the required level of quality of mechanical vibrational system without additional encapsulation (closed capsules), which is used in the prototype.

Thus, the essence of the invention can be formulated as follows.

A method for measuring the pressure difference by a sensor with a frequency-modulated output signal, which uses a membrane with resonators grown epitaxially on it, oscillates the resonators and generates an output signal, characterized in that an additional membrane with resonators is introduced with the possibility of forming a vacuum gap.

A pressure difference measuring sensor with a frequency-modulated output signal that implements the method according to claim 1, comprising a membrane with resonators epitaxially grown on it, a permanent magnet resonator excitation system and an output signal generating system, characterized in that both membranes with resonators are separated by a vacuum gap and form a body.

The invention is illustrated in the drawings: FIG. 1 is a design of the sensor, FIG. 2 is a sectional view of FIG. 1 along line AA (enlarged scale), FIG. 3 is a functional diagram of a sensor. In the drawings, the numbers indicate: 1 - the sensor housing, 2 - identical silicon membranes 2 with resonators 3, 4, a permanent magnet 5 with a magnetic core 6; excitation system of the resonators 7, the system of removal and processing of the signal 8.

The drawings show the proposed sensor. It contains a hollow body 1, a sensitive element - two independent identical silicon membranes 2 with resonators 3, 4. The resonator's own vibrations are excited as a result of the interaction of the magnetic field created by the permanent magnet 5 with the magnetic circuit 6 located in the evacuated space between the membranes with a magnetic field of current passed through the beams of the resonators.

The sensor operates as follows. Under the action of pressure forces, the membranes 2 deform, leading to the extension or compression of the resonators 3, 4 and a change in their resonant frequencies in proportion to the measured pressures.

The pressure difference is determined by comparing the resonant frequencies of the resonators of each membrane, while the natural oscillations of the resonators are provided by the Ampere force arising from the interaction of the magnetic fields of the permanent magnet and the current in the resonator excitation beam.

The sensor can be performed in both protected and unprotected versions, and can also be used as an absolute pressure sensor.

Information sources

1. US patent No. 4841775, G01L 9/00, G01L 011/00, decl. 01/19/1988, publ. 06/27/1989.

2. European patent EPO 456029 A1, G01L 11/00, application No. 91106472.3, decl. 04/23/1991, publ. 11/13/1991.

Claims (2)

1. A method of measuring the pressure difference by a sensor with a frequency-modulated output signal, which uses a membrane with resonators grown epitaxially on it, vibrates the resonators and generates an output signal, characterized in that an additional membrane with resonators is introduced with the possibility of forming a vacuum gap. 2. A pressure difference measuring sensor with a frequency-modulated output signal that implements the method according to claim 1, comprising a membrane with resonators epitaxially grown on it, a permanent magnet resonator excitation system and an output signal generating system, characterized in that both membranes are with resonators separated by a vacuum gap and form a housing.

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