SU1000773A1 - Automatic batch-type scale having digital control - Google Patents

Description

This invention relates to a weight measuring technique.

A known weight batch metering device comprising a dial pointer with an angle-of-rotation converter for linear motion associated with a displacement sensor, an analog-to-digital converter connected to an arithmetic unit connected in conjunction with a setting unit to a comparison node l1;

This device does not provide the necessary accuracy, since with changing external conditions, the parameters of the sensor and other elements of the measuring path change.

The closest to the proposed technical entity is an automatic weight portioning dispenser with digital control, containing a dial pointer with a pointer rotation angle converter into linear movement, an inductive displacement sensor, the outputs of which through a controlled switch are connected to the input of an analog-digital converter connected to an arithmetic unit, connected together with the setting device to the digital comparison unit, and the unit

control, the outputs of which are connected to the inputs of the controlled switch and to the arithmetic unit 2. In this dispenser, measures are taken to reduce the additional dosing error by measuring the unknown dose c. several cycles in conjunction with tests that were specially formed at the input of the Measuring system; This makes it possible to obtain additional information not only about the measured value, but also about the current values of the parameters of the conversion function

15 system and exclude these unstable parameters from the final result.

However, this device has low accuracy and reliability, so

20, as adopted in it, a piecewise parabolic approximation of the transformation function of the mapping system, in connection with which the number of measurement cycles needed to determine the current value of the dose is increased to four. This greatly increases the dynamic component of the measurement error.

The prototype device also has

30 significant approximation error, since the kaiusi i-th part of the transformation function, approximating with a parabola segment, cannot be less than 5 & where b- is the length from the individual section of the inductive sensor coil. Reducing the length B of the target (reducing the approximation error leads to an increase in the total number n of sections of the winding, which significantly conditions the manufacturing technology of the sensor with a large number of identical sections to one another. This, in turn, leads to the fact that inductive transducers differing in their parameters from one to another, which leads to a decrease in metering accuracy due to an increase in the non-identical error. The purpose of the invention is to improve the accuracy by decreasing the error roximets of the measuring function. This goal is achieved by the fact that the inductive displacement transducer is made in the form of two solenoid coils with ferromagnetic cores, the first of which is made of the main and two identical auxiliary sections located on its edges, and the second coil is made of one section identical to the main and one auxiliary sections of the first coil, the lever is inserted into the dispenser, one arm of which is connected by an angle-of-rotation converter of the arrow to the linear displacement, and the other on The known distances from the support of the lever are connected with the ferromagnetic cores of the inductive displacement transducer. . The drawing shows the diagram of the dispenser. The dispenser contains a dial pointer 1 with a transducer 2 of the angle of rotation of the arrow into the linear displacement, connecting with the left arm of the lever 3, an inductive sensor 4, ferromagnetic cores 5 and which is connected to the right arm of the lever 3. Sensor 4 contains two solenoid coils 7 and 8, moreover Coil 7, which has terminals 9-12, contains three sections of the main and two identical auxiliary, located along its edges. Coil 8, having conclusions .13 and 14, contains a section of the section that is identical to the main and one auxiliary section of the coil 7. Conclusions cat the lugs 7 and 8 are connected to the input of the controlled switch 15, the output of which is connected to the input of the analog-digital converter (ADC) 16. The output of the ADC 16 includes an arithmetic unit 17, the output of which is connected to one of the inputs of the digital comparison unit 18, to the second The input of which is connected to the sensor 19. To the control switch 15 and to the input of the arithmetic unit. 17, terminals of the control unit 20 are connected. The proposed dispenser works as follows. When the metered material enters the load receiving bin (not shown), the pointer of the dial indicator 1 deviates by an angle с proportional to the current value of the mass P. We have oL f (Р). The ct angle with converter 2 is converted to linear displacement X. , (°) as a result, the inductance of the sensor 4 changes as a function of the movement L fJ (x) t With the help of the A / D converter 16, L is converted into the digital code N N f (L). Thus, the code value at the output of the ADC is functionally related to the mass value P of the dosing material in the cargo: receiving bin N N (P). If the PgoL and L.Ll transformations are linear, then all subsequent transformations are non-linear. As a result, this conversion function of the metering path of the dispenser is also non-linear. The principle of operation of the Proposed dispenser is based on the fact that its conversion function can be represented with sufficient accuracy by a certain number of segments pr -. be quiet of the form: аР b, i «1,2 ,. ..n. n is the number of approximation segments, P is the measured dose; a, b are the coefficients of the transformation function determined by the physical parameters of the mass measuring system and are random functions of time. The variation of the coefficients a and b under the influence of external factors, as well as due to the time drift of the parameters of the self-measuring system, are sources of dose measurement errors. To eliminate the influence of the instability of the indicated coefficients, as well as from the values on the accuracy of dosing, spend three doses of dose measurement, during which to the input of the A / D converter 16 by means of the controlled switch 15 in any post-. The following pairs of terminals of coils 7 and 8 are connected to the practicality: terminals 9 and 11, 10 and 12, 13 and 14.

In the initial state, at P 0 I, the cores 5 and 6 are set to the same positions, respectively, relative to the coils 7 and 8. During the dosing process, as the material is fed into the receiving Sumker, the cores begin to shift in the direction indicated in FIG. 1 arrow. When the transducer 2 is displaced by distance x, the core 7 is shifted by the distance if.,. and the core 8 - by the distance K-i X. The connection to the input of the A / D converter 16 of the terminals 10 and 12 of the coil 7 instead of 9 and 11 corresponds to the displacement of the core 5 relative to this coil to the distance 9 equal to the length of the auxiliary section. Thus, the electrical signals at the output of the ADC 16 are associated with a displacement, respectively, depending on

a1c x + b,

N.

N a (k, x in) + b-,,

N5 akix + oh 25

where k and k. constant lever transfer ratios:

Ha ..,

.Ni-n,.

R - where

KI-K,

Taking into account the linear relationship between x and p for the current value of masses P, we have

.. where 1 is the proportionality coefficient, determined by the parameters of only the mechanical components of the dial indicator. In this way,

 “1-v. .

Weight calculations are performed by an arithmetic block 17.

As can be seen from the formula, the unstable parameters a and b are the meter | SID systems are not included in the final expression for P and thus their instability does not reduce the accuracy of the dose measurement. This makes it possible to increase the dosing accuracy due to the exclusion of both the multiplicative component of the error, determined by the coefficient a, and the additive component of the error, determined by the coefficient b. The accuracy of dosing depends only on the stability of the parameters (7 and k, which can be performed with the degree of accuracy required for practice

The absolute values of & and k are chosen from the condition of minimum error of the piecewise linear approximation of the conversion function of the mass-measuring system.

A signal proportional to the calculated current dose value is fed to one of the inputs of digital comparison unit 18, to the second input of which a signal proportional to the preset Dose in the setter 19 is applied. When the signals at both inputs 18 are equal, the signal for closing the inlet gate feed hopper (not shown),

A prototype of the proposed metering device was made and its laboratory tests were carried out, confirming its effectiveness and the possibility of providing high accuracy of dosing in a wide range of changes in external conditions.

The economic effect of the use of the invention is due to the increase in dosing accuracy.

thirty

Claims (1)

Invention Formula Automatic weight portioning dispenser with digital control, containing a dial indicator with 5 converting the angle of rotation of the arrow into a linear displacement, an inductive sensor moving the outputs of which through a controlled switch are connected to the input of an analog-to-digital converter connected to an arithmetic unit connected together with the setting unit to the digital comparison unit, and the control unit whose outputs connected to the inputs 5 of the controlled switch and to the arithmetic unit, characterized in that, in order to increase the accuracy, it will fall asleep to reduce the error in the approximation of the measurement It has an integral function, in it the inductive displacement transducer is made in the form of two solenoid coils with ferromagnetic cores, the first of which is made of a primary and 5 two located along its edge) 1M identical auxiliary sections, and the second coil is made of one section identical to the main and one auxiliary sections of the first bobbin, where a rachag is inserted into the dispenser, one arm of which is connected to the transducer of the angle of rotation of the arrow into a linear movement, and the other, at different distances from the support of the lever, is connected to ferromagn H-1T cores inductive displacement transducer. Sources of information taken into account in the examination USSR certificate 01G 19/34, 1965. Certificate of the USSR 01 G 13/28, 1977