SU735979A1 - Device for determining thermal effects - Google Patents

Description

I

The invention relates to the field of technical and medical physics, for example, to means of investigating the function of the external respiration of a person.

The known devices of this type are based on the presence of the temperature dependence of the pyroelectric floor in ceramics. In general, the formation of-. The signal in a pyro-ferroelectric crystal is a function of its electrical, thermal and mechanical properties or otherwise: the entropy (P), electric induction (D) and deformation (and) of the crystal are the result of forces: temperature (T), electric field ( E) and mechanical stress (6) Indicated, the parameters in the crystal are related directly to indirectly. Thus, for example, at T Jar, the induction of D changes directly and the pyroelectric effect itself arises, although induction can also occur due to thermal expansion and the piezoelectric effect.

The pyroelectric effect is caused by a direct change in the thermal energy of the crystal lattice and is not associated with its deformation. With indication of aerodynamic action. air flow, the pyroelectric coefficient should be determined by the second variation of the dielectric constant, the piezoelectric modulus, and the elastic stiffness.

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The closest in technical essence and the achieved result is a temperature sensor, made in the form of a frame frame, curved in the shape of the chin and the periphery parts of the face 2,

15 The temperature-sensitive element of the sensor is a grid of thin pro- B (Lok, temperature-sensing, which causes a change in electrical resistance and, accordingly, measured

20 output signal in the measuring circuit of the device.

The disadvantages of the known device are; the impossibility of directly measuring the energy transfer of unsteady in time flows of gas cpeflbij, the relatively low sensitivity of the thermocoupler due to the limited value of its temperature coefficient of resistance; the presence of measurement errors due to the impossibility of eliminating the influence of external heat fluxes; the selectivity of the output characteristics of the thermal converter in the infrared range, for example, from 5 to 40 microns; the inertia of the thermocouple does not allow to investigate the dynamic characteristics of the unsteady in time flow of the gas medium. The aim of the invention is to improve the accuracy and sensitivity of the determination. This is achieved in that the calorimetric cell is made flow through in the form of a pyroelectric detector trap, which is a three-way hollow regular pyramid, each side of which is 0.577 of the characteristic size of the airflow cross-section profile. One face of the pyramid is made in the form of two pyro-active plates with oppositely directed polarization and an internal mirror surface reflecting infrared rays, for example, in the range from 5 to 40 µm, the other face of the pyramid, made identical to the first face, has an inner surface. Covered, for example, with golden black, absorbing infrared rays in the same range, and a third face of the pyramid, identical to the first and second faces, is equipped with pyroactive plates with unidirectional polarization. FIG. 1 shows schematically the described device, FIG. 2 is a circuit diagram of the device; Fig, 3 is a structural diagram of the measuring complex. The device consists of a calorimetric cell 1, made, for example, in the form of a half mask 2 with a base 3, curved in the shape of a part of the face, a person, and equipped with a pyroelectric detector trap 4 representing the correct hollow triangular pyramid, each of the sides is 0.577 the size of the cross section of air flow. One face 5 of the detection trap 4

735979 is made in the form of two pyroactive plates 6 and 7, having oppositely directed polarization and a mirror surface 8, the second face 9 is made in the form of two pyroactive plates 10 and 11 with the opposite polarization direction and the inner surface 12 covered with golden niello, and the third face 13 has two pyroactive plates 14 and 15, but with an equally directed polarization and an inner surface 16, identical to the second and first facets 5 and 12. For the study of the thermal effects of a person’s external respiration, a mask 2 fortified t on the face, during which they ensure a snug fit of the base of the half mask to the abutment surface. The pyroactive plates are switched according to the measuring circuit of the device. After this operation is completed, the device is ready for operation, the sequence of which is explained by the block diagram j (cM. Fig. 3). The signals from each of the detectors 17 are fed to amplifiers 18, and a, to the switch 19, which periodically connects measuring channels to the analog-code converter 20. In the latter, the received information is converted into ten-bit binary codes, which are entered in a sequential form in the computer complex 21, built on the base of the electronic computer. The central control unit 22 of the computing complex 21 provides for the selection of a program, the implementation of which is currently required, the subsequent reading of this program and the execution of each operation separately. Periodic registration of the measured parameters was carried out on a paper roll 23 by program or by calling the operator. Long-term storage and entry into the computer complex 21 of information recorded automatically or manually is provided by an external drive on punched tape 24. The recording of the thermal effects of external breathing using the proposed device can significantly improve the accuracy (by order) compared to known devices of this type , dramatically (up to fractions of seconds) reduce the inertia of measurements, which gives not only a significant technical and economic effect, but also allows

a device for studying the dynamics of unsteady gas exchange, thermography of the human surface, etc.

Formupa invention

Claims (2)

1. A device for determining thermal effects, preferably with the external respiration of a person, consisting of a half mask, with a base; curved shape of the face, calorimetric cell, calorimeters, measuring circuit, characterized in that, in order to increase the accuracy and sensitivity of determining J, the calorimetric cell is made flowing in the form of a pyroelectric detection trap, which is a triangular hollow pyramid, each of the base is 0.577 of the characteristic size of the cross-sectional airflow profile. 2. The device according to claim 1, in accordance with the fact that one face of the pyramid is made in the form of two pyroactive ones. plates with oppositely directed polarization and an internal mirror surface that reflects infrared rays, for example, in the range from 5 to 40 μm of another side of the pyramid, are made 0 is identical to the first face, has an internal surface, covered, for example, with golden navy, absorbing infrared rays in the same range, and the third face of the pyramid is identical S of the first and second facets, equipped with pyroactive plates with equal-polarization. Information sources, 0 taken into account in the examination: 1.Moving Q.C.Ingandi U.Rev. Sci.lnst 33, 3.118, 1967. 2. USSR author's certificate No. ZO7789, class A 61 B 5/05. five 735979 wic; W {c) 111 (111  J1 JO 9 .16 J5 / 7J FIG. 2