SU1352234A1 - Force measuring device - Google Patents

Abstract

The invention can be used to measure the mass of objects. The purpose of the invention is to improve accuracy. The output of the multiplying digital-to-analog converter 13 generates a signal of a sinusoid with a frequency proportional to the frequency of the tunable generator 10. As the supply voltage fluctuates, the value of induction in the electromagnet 3 gap increases, which leads to an increase in force. The weighed element rises up and eliminates the misalignment, which is measured by the position sensor 8. 1 il. with f (/)

Description

The invention relates to a measurement technique, is intended to measure forces, and, in particular, can be used to measure the mass of objects.

The purpose of the invention is to improve accuracy.

The drawing shows a functional diagram of a device for measuring forces.

The device contains a vertically positioned weighed element 1 with a closing magnetic core 2, which is held in a weighted connection. 15 If the force developed by electromagnetism at a certain distance by an electromotor 3, is less than that required for a supporting electromagnet 3, the winding 4 of which is weighted element 1 is connected to the output of the power amplifier 5, the sensor 6 induction, performed in advance of a predetermined gap, then weighed element 1

in the form of a coil of one or one of them is lowered down. Signal from sensor 8

the number of turns of the conductor placed in the gap between the electromagnet 3 and the magnetic core 2 of the weighed element 1, the voltage from which

is fed to the first input of circuit 7 of a comparable oscillator 10. Frequency

The output of which is connected to the input of the power amplifier 5, the weighted body position sensor 8 connected in series, the dynamic correction unit 9, the frequency controlled oscillator 10, the counter 11, the code converter 12, multiply the digital-to-analog converter (DAC) 13, the second input of which connected to the output of the source 14 of the reference voltage, and the output to the second input of the comparison circuit 7, the output of the tunable generator 10 is connected to the input of the measuring unit 15, which is a series connected measurement Tel period 16, the block 17 squaring, a subtracter 18, a second input coupled to an output 19 of the initial set point weight code, and a display device unit 20 is based on the known relationship counterbalancing force developed by the electromagnet force compensation, and the period of voltage

 F CT,

where F is a force developed by an electromagnet;

T is the period of oscillation of the supply voltage; .

K - coefficient taking into account the number of turns of the coil, the area of the pole, covered by the coil.

The device works as follows.

In the initial state at the output of the dynamic correction unit 9 there is a constant voltage, which corresponds to a certain value of the output frequency of the controlled oscillator 10. This frequency exactly corresponds to the frequency of the sinusoidal signal of the calibrated amplitude fed to the input of the circuit 7 comparing the voltage stabilizing circuit, removed with induction sensor coil 6.

If the force developed by the electromagnet 3 is less than that required to support the weighed element 1 by

determined in advance of the specified clearance, then weighed zlement 1

position proportional to the amount of movement of the element to be weighed 1, the dynamic correction block 9 passes, changes the input voltage up5

the signal at the output of the controlled oscillator 10 is reduced (the period of the signal (T) is increased). In proportion to the frequency at the output of controlled generator 0, the frequency of the signal at the output of the digital sinusoid generator, which consists of, changes. the counter And, the converter 12 code, multiplying the DAC 13 and the source 4 of the reference voltage.

The digital sine wave generator works as follows.

The variable frequency signal comes from a frequency controlled 0– P ator 10 generator to counter 11, the counting coefficient of which (the number of counter states) is equal to the number of cells X (capacity) of the x / y transducer 12. Each state of the counter 11 5 corresponds to the value of the coordinate (address) X of the converter 12 of the code, in which each value of the coordinate X corresponds to a certain value of the weight of the sinusoidal signal-0 (coordinate Y). One of the possible examples of the implementation of the converter of 12 codes is the use of a ROM (K556 PT5), in the cells of which the weights of the sinusoidal signal for one period are sequentially recorded (it is also possible to realize a circuit with half or a quarter of the period). The sinusoid weight codes are fed to the multiplying DAC 13 (for example

31

572 PA1, K 572 PA2), to the analog input of which a stabilized reference voltage is applied from the voltage source 14. Thus, at the output of the multiplying DAC 13, a step sinusoid signal is generated with a frequency proportional to the frequency of the tunable generator 10. The number of sinusoid points depends on the capacity of the 12 code converter (ROM capacity) and the need to write a quarter, half or full sinusoid period in the ROM. As T increases, the value of induction in the gap of electromagnet 3 increases, which leads to an increase in force. The weighed element 1 rises up and eliminates the mismatch, which is measured by the position sensor 8.

Claims (1)

Invention Formula A force measurement device comprising a power compensation electromagnet, the winding of which is connected to the output of a power amplifier. Editor M.Petrova Order 5553/36 Compiled by V.Shirshov Tehred.M.Morgental i Corrector I.Musk Circulation 694 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4 52234 comparison circuit, reference voltage source, position sensor of the weighed element connected to g to the dynamic correction unit, an induction sensor, placed under a power compensation electromagnet, a frequency controlled oscillator and a measuring unit, differing in that, in order to improve accuracy, a counter ,, a code converter and a multiplying digital-analog converter are entered into it, the counter output is connected via 15 code converter to the first input of the multiplying digital-analog converter, to the second input of which a voltage source is connected, and to the output - the first input of the comparison circuit, the second input of which is connected to the induction sensor, and the output of the dynamic correction unit connected to the input controlled by 25 frequency generator, the output of which is connected to the inputs of the counter and the measuring unit.