SU1428941A1 - Filled-system liquid-type thermometer - Google Patents

Abstract

The invention relates to thermometry and allows to simplify the design of the device, to reduce its dimensions and weight. Corrugated membranes 4, 20 are fixed in measuring and compensation thermosystems

Description

31

IS

i

(j

with

flanges attached to the bearing flanges 3.22, respectively. The opposite side of the flanges 3.22 are in contact with the bellows 5.21. When the medium changes, the volume of fluid in the thermal bottle I connected by capillary 2 to the flange 3 changes. Operating pressure of the measuring thermosystem

causes movement of the lever system of block 15. The effective area of the membrane 4 (20) is at least three times the effective area of the bellows 5 (21). Both thermal systems are fixed on the case of the thermometer 11 and filled with a thermometric liquid .. 1 Ш1 „

The invention relates to instrumentation, namely, devices for measuring temperature, and can be used in systems for automatic monitoring and control of the temperature regimes of industrial technological processes in the chemical, petrochemical and other industries.

The aim of the invention is to simplify the design and reduce the size and weight of a liquid manometric thermometer.

The drawing shows a schematic diagram of the proposed device.

The measuring system of a manometric thermometer contains a thermotube 15 connected by a capillary 2 to the reference flange 3 of the measuring thermosystem, to the upper end of which a measuring corrugated membrane 4 is welded, and to the lower end a fixed shoulder of the setting bellows 5 of the working pressure formation unit is welded; bottom 6. Inside the bellows 5, the ram (en limiter 7 volume and displacement. The inner cavities of the membrane 4 and bellows 5 are communicated by channel 8, which channel 9 communicates with the capillary rum 2. The internal cavity of the measurement of the thermal system

filled with thermometric fluid 10.- Measuring thermosystem for replenishing the thermometer case 1 1 with studs 12 and nuts 13 and 4. The movable center of the membrane 4 is connected to the force conversion unit 15 into a pneumatic output signal with the primary lever 16 of the unit.

0

five

p 5 p

five

0

The block 15 contains a nozzle-flap assembly, the flap J7 of which is connected to the lever 6, and the nozzle 18 is fixed on the body of the block 15. The lever 16 has a support 19 of rotation.

The compensation thermosystem contains the measuring corrugated membrane 20 and the defining bellows 21 of the working pressure formation unit welded to the opposite ends of the support flange 22. The movable end of the bellows 21 is sealed by the bottom 23 Inside the bellows 21 a limiter 24 of volume and displacement is placed. The internal cavities of the membrane 20 and bellows 21 are communicated by channel 25 between themselves and channel 26 with fake aplrom 27 welded to flange 22. The compensation thermosystem is filled with thermometric liquid 10 and fixed to the case of thermometer I1 with studs 28 and nuts 29 and 30. Mobile center the membrane 20 is connected to the lever 16 of the block 15.

The volume of fluid in the compensatory thermosystem is equal to the volume in the outer part of the measuring thermosystem (except for the volume of fluid in the thermowell, which is provided when adjusting the thermometer.

Block 15 also contains a feedback bellows 31, a pneumatic gauge 32, a zero offset 33, and a pad 34,

The device works as follows.

The bulb 1 is placed in an environment whose temperature is to be measured. In the steady state, the kinematic system of the thermometer is in equilibrium: the nozzle-flap is set at the node

the gap, which ensures the processing of the output signal corresponding to the steady-state temperature of the medium.

When changing, for example, as the temperature of the medium rises, the temperature of the thermowell 1 and the thermometric liquid inside the thermowell increases, as a result of which the volume increases. liquids in a thermo-bottle by the magnitude of a linac "This excess volume of thermometric fluid uV through the distance capillary 2 flows into the cavity of membrane 4 and bellows 5, and since the movement of the moving center of membrane 4 is limited by the power compensation system of unit 15, the change in fluid volume & V will cause the movement of the movable bottom 6 bellows 5. This movement is expressed by the formula

 -

Where

7

d

IS

where L is the movement of the master

bellows;

 Sj, g is the effective area of the defining bellows of the measuring thermosystem. Moving the driver bellows 5 by the value of & L from the side of the thermometric fluid will require effort

yr-A, (2)

- force of elasticity of the bellows;

-The rigidity of the setting bellows of the measuring thermosystem.

In turn, on the side of the bellows 5, the reaction R acts on the side of the bellows, the value of which is equal to the force of elasticity FU

 R (3)

Reaction R is the force from which the bellows 5 acts on the thermometric fluid, forms the working pressure in the measuring thermosystem.

, g. with

This working pressure is set in the entire liquid volume of the measuring thermosystem and causes an operating force on the rigid center of the measuring diaphragm 4

FP Pp SHM (5)

where S., is the effective area of

measuring membrane.

The working force Fp is transmitted to the lever system of the block 15, and

the interposition of this system at a certain angle, establish a new position (smaller gap) in the nozzle-flap assembly and a new value of the output signal () of the thermometer. At the same time, the output pressure P ,, through the sylphon 31 of the feedback, limits the movement of the kinemat-1 system of unit 15 (the principle of power compensation) in the range of 0.005-0.01 mm.

The change in the volume of the thermometric liquid uV depends on the initial volume of the liquid in the bulb

,

15

Where

20

25

DU V. p, ut, (6)

V is the volume of fluid in the bulb;

B — coefficient of temperature volumetric expansion of a thermometric liquid; ut is the change in temperature of the controlled medium.

Substituting the values (A), (3), (2), (1) and (6) into (5), we obtain (after transformations)

S and.M Z I

Fp

-J. WITH

 u

.

(7)

thirty

35

40

50

55

By choosing the parameters of the elements of the measuring thermosystem accordingly, the desired value of the working force of the thermometer can be obtained, i.e. create a high-sensitivity and precision gauge thermometer for a given scale range.

Applying the unified pneumatic-power converter of the GPS system with the measuring range O - 1, OKGS as a unit for converting the force into the output pneumatic signal, it is possible to provide a measurement of the temperature of the controlled medium by the device in a wide range of operating temperatures at a small / about 10 ° with scale range. Changing the range of the thermometer scale is provided by moving the movable support 34 along the lever 16 in block 15, and the offset of the measurement limits (set to zero) is set by the control unit on the bulb 1.

To ensure normal operation of a manometric thermometer in a wide range of ambient air temperatures, to which all thermometer elements are exposed, except for a thermometer and for industrial thermometers, the range of measuring the ambient air temperature can often be from -50 to +50 s) in the thermometer compensation thermosystem and in the outer part of the measuring thermosystem.

In addition, it is necessary to ensure the working deformation of the setting bellows by the measuring and compensating thermosystem in the deformation zone of one sign (in this case, in the zone of expansion deformation), which is achieved by preliminary deformation (stretching of the setting bellows by the calculated value when filling the thermosystems with liquid and setting thermo | M etra,

To ensure deformations of the reference bellows within the limits of displacement permitted by these GOST bellows, it is necessary to minimize the absolute values of the volumes of thermometric liquid in thermometers, which is ensured by using corrugated membranes as measuring sensors, introducing volume restraints into thermosystems and choosing the ratio of the effective areas of the measuring membrane to the effective

the areas of the specifying bellows are at least three.

Formulas and inventions A manometric liquid thermometer containing measuring and compensating thermosystems with units for forming working pressures and a unit for converting measurement results into an output signal, wherein the measuring thermosystem also contains a thermometer and a remote capillary, characterized in that, in order to simplify the structure, reducing the size and weight, the support flange is inserted into it; the measuring elastic element of each thermal system is made in the form of a sealed corrugated membrane, not Vision shoulder which is attached to the bearing flange of the thermal system, on the opposite side of which is attached sealed nepodvizhnsh shoulder master bellows, the inner cavity of which fluidly communicates with the interior of a sealed bellows, the effective membrane area is at least three times prevshaet effective area of the master bellows.

Claims (1)

Formula of the invention A manometric liquid thermometer comprising a measuring and compensation thermosystem with units for generating working pressures and a unit for converting the measurement results into an output signal, the measuring thermosystem also comprising a thermoball and a remote capillary, characterized in that, in order to simplify the design, reduce the size and weight, a support flange is inserted into it, the measuring elastic element of each thermosystem is made in the form of a sealed corrugated membrane, fixed the collar of which is attached to the support flange of the thermal system, on the opposite side of which is attached the fixed collar of a sealed master bellows, 25 whose internal cavity is hydraulically connected to the internal cavity of the sealed corrugated membrane, while the effective membrane area is at least three times the effective area of the master bellows.