SU1530931A1 - Weighing apparatus - Google Patents

Abstract

A weighing device comprising a housing with a base, a weighing platform, kinematically associated with a piezoquartz force sensor, an electronic exciter and an indicator, characterized in that, in order to improve accuracy by measuring simultaneously through two channels, piezoquartz saddles-inserts are introduced into it, electronic pathogens, an adder, a comparator and an additional indicator, the piezoquartz force sensor being made in the form of interconnected piezoquartz prisms with Support and load edges that are connected via piezoquartz seat inserts, respectively, to the base of the body and the load-receiving platform, metal electrodes connected to the inputs of the corresponding additional electronic exciters, whose outputs are connected to the input of the adder, connected to additional indicator and other input of the comparator.

Description

The invention relates to weighing technology, in particular to devices in which weighting is carried out by measuring changes in the oscillation frequency of an elastic element.

The purpose of the invention is to improve accuracy by simultaneously measuring in two channels.

The drawing shows a diagram of the device.

On the body 1, the side walls 2 are reinforced. In the upper part of the device a mass-receiving platform 3 is placed. Inside the body 1 there are placed piezo-quartz sensors to a force, including jumper 4, on which are deposited metal electrodes 5 and conjugate piezo-quartz prisms 6 and 7, which have bevelled supporting faces B, 9 and beveled load faces 10, 11.

The beveled support faces 8 and 9 are supported on piezoquartz seat inserts 12 and 13, on which metal electrodes 14 and 15 are applied.

The beveled load faces 10 and 11 are mated to saddles-inserts 16 and 17, on which metal electrodes 18 and 19 are applied.

Metal electrodes 5 jumpers 4 are connected to the input of the electron-.

ate

with about

WITH

00

Foot 20, the output of which is connected to the input of the first indicator 21 and the first input of the comparator 22.

The metal electrodes 14 of the first saddle-insert 12 are connected to the input of the second electronic exciter 23, the output of which is connected to the first input of the adder 24.

Metal electrodes 15 of the second saddle-insert 13 is connected to the input of the third electronic exciter 25, the output of which is connected to the second input of the adder 24.

Metal electrodes 18 of the third saddle-insert 16 is connected to the input of the fourth electronic exciter 26, the output of which is connected to the third input of the adder 24.

The metal electrodes 19 of the fourth saddle-insert 17 are connected to the input of a fifth electronic exciter 27, the output of which is connected to the fourth input of the adder 24, the output of which is connected to the input of the second indicator 28 and the second input of the comparator 22,

The operation of the device is based on the direct and inverse piezoelectric effects, the silofrequency and twoformation-frequency effects of piezoquartz resonators.

In the initial position, a power supply is applied to electronic pathogens 20 23, 25, 26, and 27, adder 24, and indicators 21 and 28 from a power supply unit (not shown).

Electronic pathogens 20, 23, 25, 26, and 27 excite piezoelectric oscillations in subelectrode piezoquartz zones (under metal electrodes 5, 14, 15, 18, and 19).

In the absence of the mass of the object being measured on the mass-receiving platform 3, the frequency of the piezoelectric oscillations in the localized zone under the electrodes 5 and in the localized zones of the piezoelectric saddles-inserts 12, 13, 16 and 17 under the electrodes 14, 15, 18 and 19, respectively, is equal to the initial values f, , f, f, f.

When a measurement object with a mass tp is placed on a mass-receiving platform 3, a force F arises, which acts along the loading axis 0-0.

Under the action of the force vector F, two moments MI and M are produced, acting in opposition to jumper 4, because

0

five

Q

,

five

five

The bevels of the supporting and loading faces of each piezoquartz pr-t are made in opposite directions.

Moments M and Mj are respectively equal

m, - I -1; M G I H

where 1 is the distance between the vertices of the beveled support and load faces of the first conjugate piezoquartz prism;

12 - the distance between the vertices of the oblique support and load faces of the second conjugate piezoquartz prism

due to the effect of the force-frequency effect in the localized zone (under the electrodes 5) of jumper 4, the frequency of the piezoelectric oscillations is reduced by the value of L,

if K. Llklk i D n- 2

where Kg - silofrekty); coefficient; F is the magnitude of the force vector fo is the initial value of the frequency; D - geometric factor - cross section of the jumper;

n is the harmonic number; - efficiency of the contacting, mechanical parts.

An electrical signal whose frequency has changed by the value of ttf, is fed through the electronic exciter 20 to the first indicator 21 and is indicated therein in units of mass, since the relationship between the magnitude of the measured mass and the deviation of the frequency of the piezoelectric oscillations is proportional. At the same time, this signal is applied to the first input of the comparator 22.

The force vector F in the piezoquartz saddle inserts 12, 14, 16, and 19 creates a mechanical compressive voltage, which causes an increase in the frequency of the piezoelectric oscillations in accordance with the frequency-effect

- f if ..- ufs-K

51530931

uf ", b.f, bf 4 the frequency deviation of the piezoelectric oscillations from the initial value - (in the piezoelectric saddles-inserts 12, 13, 16, and 19) under the action of the force vector F

 if, -Af, if, if, K, li-lLU,

where m is the mass of the object being measured;

 initial values

the frequency of the piezoelectric oscillations in the piezoelectric saddles inserts 12, 13, 16 and 17.

The electrical signals (with the indicated frequencies) from the saddles 12, 14, 16 and 19 through the corresponding electronic exciters 23, 25, 26 and 27 are fed to the corresponding inputs of the adder 24, from the output of which, after algebraic summation, an electrical signal of the total increment frequencies

& f./i f, 0 Af “u f, 5 -or

,

0 5

0

 f

The -i-f-electric signal of the cumulative frequency i ".", is displayed on the display of the indicator 28 in terms of mass and is simultaneously applied to the second input of the comparator 22.

The electrical signal in frequency, corresponding to the measured mass of the object, measured on the first channel, supplied to the first indicator 21 and the first input of the comparator 22 normally (in the absence of a malfunction and significant interfering interference) is equal in frequency to the electric signal taken from the second channel the indicator 28 and the second input of the comparator 22.

In the case of a frequency deviation of one of the channels (corresponding to 11 11, the measured mass of the object to be measured) above the norm, a signal is output from the upper output of the comparator 22.

In the event of a frequency deviation of one of the channels below the norm, a signal is output from the lower output of the comparator 22.

P J 5 P19 J 7 o t

Claims (1)

MEASURING DEVICE, comprising a housing with a base, a load receiving platform kinematically connected with a piezoelectric quartz force sensor, an electronic exciter and an indicator, characterized in that, in order to increase