SU1509769A1 - Seismometer - Google Patents

Abstract

The invention relates to geophysical instrumentation and can be used in seismometers and gravimeters. In order to increase the resolution of the seismometer by reducing its temperature errors, the metal casing of the seismometer with thermal insulation coating has an opening with an elastic membrane 7, which makes it possible to equalize the pressure in the internal volume of the seismometer and to prevent it from penetrating moisture. The air space inside the seismometer body is filled with solid heat insulating material (wood, ebonite), and the spring 2 or elastic hinges 3 are placed in a chamber with a heat insulating coating. Reducing the free air volume inside the seismometer body allows reducing the amplitude of temperature fluctuations of the baric origin in the internal volume of the seismometer. At the same time, the placement of the spring and elastic hinges in the chambers with a small volume of air leads to an additional decrease in the amplitude of temperature fluctuations acting on these temperature-sensitive elements of the seismometer design. 2 hp f-ly, 1 ill.

Description

 63 W 9 2

eight

01

about

with

ABOUT

with

1509769

The invention relates to geophysical instrumentation and can be used in seismometers, gravimeters.

The purpose of the invention is to increase the resolution of the seismometer by reducing temperature errors.

The drawing shows a seismometer.

A sensitive system consisting of an inert mass 1, suspended by means of a spring 2 and elastic hinges 3 to 4 based devices, is placed

  п §А Р 4. V

dt

25 where lt

t UP

R

V

35

R

in case 5 with heat insulating coating 5, taking into account the heat exchange of air 6, made, for example, from. with details and body of foam seismometer. The hole with elastic is described by the system of equations: the membrane 7 allows to equalize the pressure in the internal volume of the seismometer and at the same time. To prevent its 20 from penetration of moisture. The air space inside the enclosure, which usually has a complex configuration, is filled with parts from solid heat insulating material 8, for example wood, ebonite. The residual air volume is determined by the space required for the free movement of the moving systems of the seismometer. The spring is placed in a metal chamber 30 9, for example, from aluminum with a thermal insulation coating 10, for example, from ebonite.

The seismometer works as follows.

External fluctuations of atmospheric pressure freely penetrate through the housing 5 with a thermal insulating coating 6, equipped with an elastic membrane 7, into the internal volume of the seismometer, 40 without deformation of the housing and the occurrence of instrumental seismometer noise associated with them. Temperature fluctuations of pressure origin occur inside the seismometer body, the amplitude of which is proportional to the volume of air inside the body. The fluctuations in air temperature arising in the internal volume of the seismometer affect the suspension system of the inertial mass 1 of the tandem, causing temperature changes in the stiffness of the spring 2 and elastic hinges 3 and the appearance of the associated temperature characteristics of the Ggnika.

Filling the free internal volume of the seismometer with parts from solid heat insulating material 8, placing the spring in a metal frame

- increment temperature

- the spirit;

-time

- increment of atmospheric and laziness;

- average pressure

-the average value of the air volume inside the case;

- air heat capacity at constant volume;

-. air heat capacity at

constant pressure; Q is the amount of heat involved in the volume;

p | - heat transfer coefficient. The solution of system (1) relative to BT gives:

-G- V

with;

duP dt

45

50

From equation (2), the dependence of the amplitude of temperature fluctuations and air T in the internal volume of the seismometer depends on the amplitude of pressure oscillations depending on the frequency of oscillations:

 V iQ Р Cp (iW + Wo) - cyclic frequency of oscillations;

& T where CO

. ".

- characteristic frequencies

Dp of high frequencies with CO WITH the process is adiabatic, those

measure 9 with an external thermal insulation coating 10 and elastic hinges 3 in: thermal insulation chambers leads to a decrease in the amplitude of air temperature fluctuations of baric origin affecting the heat-sensitive elements of the seismometer (spring, elastic hinges), reducing temperature errors and increasing the resolution of the seismometer.

Inside the seismometer body, a thermodynamic process is performed, to a clause §A R 4. V

 taking into account the heat exchange between the air al mi and the seismometer housing, it is a system of equations:

(one)

but

where lt

t UP

R

V

R

Secondly, taking into account the heat exchange of air with the parts and the body of the seismometer, is described by the system of equations:

-increasing air temperature;

-time

- increment of atmospheric pressure;

- average pressure value;

-the average value of the air volume inside the body;

- air heat capacity at constant volume;

-. air heat capacity at

constant pressure; Q - the amount of heat involved in the volume;

p | - heat transfer coefficient. The solution of system (1) with respect to bt gives

 V

with;

duP dt

(2)

From equation (2), the dependence of the amplitude of temperature fluctuations and T of air in the internal volume of the seismometer on the amplitude of pressure fluctuations depending on the frequency of oscillations is found:

 V iQ Р Cp (iW + Wo) - cyclic frequency of oscillations;

& T where CO

(3)

. ".

- characteristic frequency.

At high frequencies, with CO – CO, the process is adiabatic, the heat exchange between the air and the surrounding bodies does not increase, while

V. 1

JiT /

Where

W.COo Po ---- LR Wed

(four)

Ar

We have the specific heat of air at constant pressure; p - the average density

of air.

For low frequencies, the process, due to heat transfer, approaches, in the limit at Q-O, to an isometric one, while

Bt /,

-SOLR.

(five)

For typical seismometer designs, the operating frequency range, as established experimentally, belongs to the transition region from the adiabatic to the isothermal process, in which, as can be seen from equation (5), the temperature change is proportional to the internal air volume, the rate of pressure change and inversely filled the space inside the seismometer housing with any material remains the remaining air volume V, for which the temperature change is air and with a constant heat transfer coefficient will be

iT,

.

9769

five

The degree of reduction of temperature variations inside the seismometer and, consequently, the degree of decrease in temperature.

errors due to variations in atmospheric pressure is determined by the ratio

(

 v.

at

20

15

25

thirty

Claims (3)

1. A seismometer, including a body with a heat insulating coating, an inert mass, a suspension with elastic hinges and a spring, characterized in that, in order to increase the resolution of the seismometer by reducing the temperature errors, the body is equipped with an opening with an elastic membrane, and body volume filled with solid insulating material. 2. Seismometer pop. 1, characterized in that the spring is placed in a metal chamber with an outer thermal insulation coating. I 3. A seismometer according to claim 1, characterized in that the elastic hinges are housed in chambers of heat insulating material.