RU1779987C - Measuring chamber of magnetomechanical gas analyzer - Google Patents

Abstract

SUMMARY OF THE INVENTION: A prefabricated magnetic system is used, which is part of the measuring chamber of a gas analyzer and consists of uniformly magnetized sections. The direction of their magnetization is calculated from the above relations. In addition, the cross section of the elements of the magnetic system can be triangular. 3 ill. sl c

Description

The invention relates to gas analytical instrumentation and can be used in industrial medicine and other fields where it is required to determine the content of a component in gas mixtures, as well as a primary converter in control and automatic control systems, the content of gas components in breathing and other gas mixtures .

Known magnetomechanical gas analyzer ne oxygen containing a magnetic system (MS), forming an inhomogeneous magnetic field, between the poles of which is the receiving chamber 1.

A disadvantage of such a device is the low sensitivity and accuracy of measurements due to the low field intensity in the working volume.

Also known is a magnetomechanical compensating gas analyzer of oxygen containing MS, which creates an inhomogeneous field in the working area due to the shape of the pole pieces 2.

The disadvantage of this design is the low sensitivity and accuracy of measurements, as well as its large mass, a significant part of which is the magnetic circuit MS.

Closest to the technical nature of the proposed invention is a measuring chamber of a magnetomechanical gas analyzer on an oxygen-containing MS with pole tips, between which is located

3 3

00

Vj

p arctg -f + 3e

ABOUT)

sensitive element (rotor) 3. The specified design of the measuring chamber of the gas analyzer is selected as a prototype.

The disadvantage of this device is its low sensitivity and accuracy, as well as its large mass. These drawbacks are associated with the non-optimal design of the MS.

The purpose of the invention is to increase the sensitivity and accuracy of measurements, as well as to reduce the mass of the gas analyzer.

This goal is achieved by performing in the measuring chamber a magnetomechanical gas analyzer containing an MS with a working gap, located in the housing with inlet and outlet nozzles, and a rotary rotor located in the working gap of the magnetic system, and the direction of magnetization of the elements of the composite magnets of the magnetic system is the transverse axis of symmetry of the magnetic system in the plane of the rotor is an angle determined from the relation

BJ, Blc

to the transverse axis of the system, coinciding with

direction of rotation

rotor

where j is the number of the portion of the magnetic system:

BxJ / BxdS; By / BjdS (2)

Sjs

Sj is the cross-sectional area of the j-ro site;

Bx, By are the components of the induction vector in the working area of the gas analyzer.

In order to provide the indicated magnetization orientation (OH) in the MS regions, the latter should be made of highly coercive PM, for example, KC37, Nd-Fe-B, etc.

A distinctive feature of the proposed measuring chamber of the magnetomechanical gas analyzer is the MS, which is a prefabricated design with optimal OH in areas that have not been previously used.

The proposed design of the measuring chamber of the magnetomechanical gas analyzer will significantly increase the sensitivity and accuracy of measuring the concentration of gas in the mixture by increasing the intensity of the magnetic field in the working area of the gas analyzer. In addition, the weight of the measuring chamber is significantly reduced, since The MS of the proposed design from highly coercive hard magnetic materials is made without a magnetic circuit.

Figure 1 shows the design of the proposed measuring chamber of a magnetomechanical gas analyzer, consisting of a magnetic system 1 and rotor 2. Figure 2 shows a cross section of an MS consisting of 16 sections, and the optimal orientation of the magnetization in the sections obtained by

formula (1). In the case when the sections have a cross-sectional dimension of 5x5 mm and the working gap is 3 mm, the optimal values of the angles shown are: f φ 36 °; y (pi -28 °, rz 61 °, 13 °. In other MS sections

the optimal OH is easy to obtain, taking into account the symmetry of the distribution of magnetization with respect to the longitudinal d - d and transverse q - q axes of the MS, It must be taken into account that the optimal OH in the MS regions is independent

on the magnitude of the magnetization, i.e. from the type of hard magnetic material (MTM). In this connection, it is possible to fabricate MS from various highly coercive MTMs. However, sections of their MTM of the same type should be located in the MS symmetrically with respect to the longitudinal d - d and transverse q - q axes of the MS. The permissible angle of deviation of OH from the optimum value is + 3 °. Increasing this angle decreases the floor

the working area of the gas analyzer by 5% or more. The angle of disorientation of the magnetization of individual sections of the MS is less than 3 ° is practically difficult to achieve with the processing, magnetization and assembly of the MS.

To reduce the complexity of assembling the MS, the options shown in FIG. 3 are possible.

The magnetic system is made as follows.

The indicated sections are cut from rectangular blanks of PM or the indicated profile sections of MS are pressed in special molds; the shape and dimensions of such sections of PM with a straight texture are determined at the stage of designing the MS. Then, the sections are magnetized individually along the texture and assembled, connecting separate parts of the MS. for example, epoxy glue. When assembling necessary

to ensure that the axes of easy magnetization coincide with the MS region with the magnetization orientation calculated by formula (1). After assembly, the MS is ready for use and can be placed in the housing of the measuring chamber

gas analyzer.

The proposed design of the measuring chamber of the magnetic-mechanical gas analyzer in comparison with the prototype provides a higher intensity of the floor in the working area, which leads to an increase in the rotating mechanical moment acting on the working body of the gas analyzer.

Due to the increase in the field, the sensitivity of the gas analyzer and the accuracy of measuring the gas concentration increase, since the gas analyzer rotates a larger angle.

In addition, the MS of the gas analyzer can be performed without a magnetic circuit (PM), because and without it, high floor intensity is provided due to the proposed construction. The latter advantage is very important for avionics.

These advantages are provided by optimal OH at the precast MS sites. The orientation of the magnetization described by formula (1) provides the highest intensity of the MS field in the center of the working zone of the gas analyzer. The latter is one of the conditions for the effective operation of a gas analyzer, since the mechanical torque acting on the working body of the gas analyzer is

M fcvHAHI. (3)

where k is the volumetric magnetic susceptibility of the test gas;

v is the volume occupied by the gas on the working fluid (rotor);

H is the intensity of the STDI MS in the center of the working area;

LN - gradient floor MS;

I is the length of the rotor.

We show that OH is described by formula (1). According to the theory of flux linkage, the magnetic flux generated by the PM through a given surface is

 J, (4)

1 V

where I is the current flowing along the surface contour, agreed in the direction of the positive normal to the surface by the rule of the propeller,

v is the volume of PM

J3 - field created by current,

O - magnetization PM.

From (4) it follows that to ensure the maximum magnetic flux (in this case, magnetic induction), the orientation of vectors B and 5 must coincide. Thus, the optimal OH coincides with the orientation of the field of the indicated current.

In the case of the MS of the gas analyzer, as a surface through which the magnetic flux is maximized, it is necessary to take a very narrow strip passing through

the center of the workspace and parallel to the longitudinal axis of the MS. The circuit through which current flows, creating an optimal orienting magnetic field, represents a two-wire line (for a two-dimensional model of the MS, i.e. in the case of a plane-parallel field).

As is known, a current loop is equivalent (in the sense of creating a floor) to a magnetic sheet. In this case, a two-wire line is equivalent to a linear magnetic dipole, because the magnetic sheet is an infinitely thin strip. In this regard, OH coincides with the orientation of the field of a linear dipole, because MS sections are made of PM with a linear texture, then to determine the average (in the jth section) value of the optimal OH, it is necessary to integrate each component of the dipole field and substitute the indicated integrals in (1). - The arc tangent in (1) should be calculated with taking into account the numerator and denominator signs,

Tests show that the MS, made according to the scheme of FIG. 2, provides a 50% higher floor intensity than the MS prototype. The mass of the gas analyzer with the proposed MS is 30% less. The proposed measuring chamber of the magnetomechanical gas analyzer

ensures the achievement of the specified goal, and the positive effect is brightly contaminated.

Claims (2)

1. The measuring chamber of the magnetomechanical gas analyzer, comprising a magnetic system with a working gap, located in the housing with inlet and outlet nozzles, and a rotary rotor located in the working gap of the magnetic system, characterized in that, in order to increase the sensitivity, the magnetic system is made in the form of two opposite composite permanent magnets, and the direction of magnetization of the elements of composite permanent magnets is with the transverse axis of symmetry of the magnetic system in the plane of the rotational ora angle defined by the relationship: BL de agsgd -Ј ± 3 °. Bi where Bx / BxdS; Woo / BydS, Slsi Si is the cross-sectional area of the j-ro element of the composite permanent magnet; Вх, By are the components of the field of a linear magnetic dipole oriented along the longitudinal axis of the magnetic system. 2. The chamber according to claim 1, characterized in that, in order to improve manufacturability, the elements of the composite permanent magnets are made with a triangular section. ft./