SU1255869A2 - Weighing device - Google Patents

Abstract

The invention relates to a weight measuring technique and allows for improved measurement reliability. During self-excitation of the device, at the output of the trigger 10, rectangular pulses are formed, differentiated by elements 20 and 21. Normalized rectangular pulses are formed at the output of the inverter 22, which through a resistor 28 and a diode 29 arrive at a capacitor 33. A logical unit from the output of the inverter 23 through a resistor 26 and The diode 27 carries out charging of the capacitor 33, which allows continuous confirmation of the signal of the unit at the output of the inverter 25 and thereby fixes the trigger 10 in the state of the weighing end. The return of frequency-selective evil. Step 19 is reset to the initial state by opening the transistor switch 34 according to the signal from the control unit 18. The capacitor 33 is discharged, the zero signal is restored at the output of the inverter 23, and the charging of the capacitor 33 is stopped. Diodes 27 and 29 serve to isolate the signal of the charge of the capacitor 33. The frequency-selective element 19 performs the function of eliminating the consequence of an error (L

Description

17.SSR69

extinguishing oscillations at self-excited-weighed doses) g zadangergoy. The Scientific Research Institute of the Device allows to exclude retention in addition to the main auto-oscillation on the border of the comparison of auth. N ° 673861. 3 Il.

one

The invention relates to a weight-measuring technique, in particular, devices for metering mixture components, for example, concrete mixes, and is an improvement on the known auto-metering device. No. 673861.

A device for dosing is known, which contains a feeder and a dosing drive, a resolver, a dosing rate sensor, a dynamic correction unit, five pulse shapers, a 1K-trigger power source, two AND elements, an RS-flip-flop, a dose setter phase shifter, and a dose setting indicator, an indicator of the current value of the dose mass, and a control unit.

The selsyn sensor rotor is connected to the axis of the needle of the dose indicator of the accumulator of the dispenser. A metering speed sensor is connected to the same axis, the output of which is connected to the first input of the dynamic correction unit. The second input of this block is connected to the rossis of the selsyn sensor, and the first output is connected to the input of the first pulse shaper. A dose setting phase shifter is connected to a second pulse shaper associated with a dose setting indicator. The first and second outputs of the control unit are respectively connected with the feeder and the dispenser accumulator. The setup input RS-trigger is connected to the output of the first element And, the first input of which is connected to the output of the fourth pulse shaper. The input of the fourth pulse driver is connected to the second output of the dynamic correction unit, and the second input of the first element I is connected with the output of the third pulse driver, the input of which is connected to a power source connected to the input of the fifth pulse driver, the output of which is connected to the riepntJM input secondly

element And with the first and second inputs of 1K-flip-flop. The output of the second element And is connected to the reset input of the RS flip-flop. The fourth and fifth inputs of the 1K-flip-flop are connected respectively to the direct and inverse outputs of the second pulse driver, and the inverse output of the 1K-flip-flop is connected to the input of the control unit.

The aim of the invention is to improve the reliability of measurement by eliminating auto-oscillations in the device at the boundary comparing the weighed dose with the target.

FIG. 1 is a block diagram of a dosing device; Fig. 2 shows oscillograms of signals of the elements of the device; Fig. 3 is a diagram of the frequency-selective element included in the device for dispensing.

Device for dosing. (Fig. 1) contains dosing device 1, selsyn sensor 2, dosing speed sensor 3, dynamic correction unit 4, first 5 pulse shaper, fourth and fifth shaper 6 and 7 pulses, power supply 8, third shaper 9 pulses

1K trigger 10, elements 11 and 12, RS trigger 13, second driver 14 pulses, phase shifter 15 dose setting device, dose setting indicator 16, current value indicator 17

the mass of the dose, the control unit 18 and the frequency-selective element 19. The frequency-selective element 19 (FIG. 3) consists of a differentiating circuit made on a capacitor 20 and a resistor 21, two inverters 22, three inverters 23-25, a resistor 26, a diode . 27, resistor 28, diode 29, zmitterna repeater, implemented on two transistors

30 and. 31 and the resistor 32, the charge capacitor 33 and the transistor 30.

The differentiating circuit 20 and 21, connected by its input to the inverted output of trigger 10, is connected via two inverters 22 and a resistor 28 to the anode of diode 29. The cathodes of diodes 27 and 29 are combined and connected to the positive input of a charge capacitor 33, an input of a sump repeater 30-32 and the emitter of the transistor switch 34. The collector of the switch 34 is connected to the negative input of the charging capacitor 33, and the base is connected to the third output of the control unit 18. The output of the zmitter repeater 30-32 is connected to the input of the inverter 25, the output of which is connected to the inputs of the inverters 23 and 24. The output of the inverter 24 is connected to the setup input of the trigger 10, and the output of the inverter 23 is connected via a resistor 26 to the anode of the diode 27.

The device works as follows.

The angular position of the indicator of the dose indicator of the accumulator of the dispenser 1 is transformed by a selsyn sensor 2 operating in a multiphase induction phase shifter mode, the voltage of which is proportional to the angle of rotation of the scale arrow forms 5 pulses forming a sequence of pulses, the phase shift of which is determined by the phase shift of voltage single-phase winding of the rosus of the sensor 2 with respect to the phase of the reference voltage of the network.

The dose reference is set by the indicator 16 setting the dose by the resistor multiphase phase shifter 15, the voltage phase of which is proportional to the angular position of the variable resistor motor of the phase shifter. The voltage from the phase shifter 15 is fed to the input of the imaging unit 14 impulses of the dose setter, which forms a sequence, rectangular pulses, duration which is determined by the phase shift of the voltage of the phase shifter 14 relative to the phase of the reference voltage of the network.

Pointed impulses of the driver 5 pulses and rectangular impulses of the driver 14 pulses arrive at the corresponding inputs (4th and 5th) of the trigger 10.

The levels and phases of the signal elements of the device are illustrated in FIG. 2, which shows waveforms of sig

ten

15

20

25 30

45

2558694

reference voltage U

35

40

50

55

on you

during the shaper 9 and the blocking signal Ug synchronized with it at the output of the shaper 7, the signal of the current mass U and the locking signal Ug synchronized with it at the outputs of the shaper 5 and 6, the signal of the shaper 14 pulses of the setpoint generator (direct U (j and inverse) , the trigger signal 13 of the current mass value and the trigger control signal of the 10 dose.

If the current mass value, determined by the position of the pulse U, is less than the mass defined by the signal 11 (Fig. 2, a), then the input of the 1-flip-flop 10 is applied to the low level Uy, and to the input K - the high level U. The trigger 10 issues signal for continued dosing.

When the dose reaches a given value (Fig. 2, b), a high level U ,, is applied to the input I of the trigger 10, and a low level Uy is fed to the input K and the trigger 10 under the action of the impulse lSf overturns the trigger 10 and gives a signal and. on the control unit 18 on dosing termination.

The on-line control of the current mass value of the component being weighed is carried out using an indicator 17 connected to the main and inverse outputs of the trigger 13.

The deflection angle of the indicator hand 17 is determined by the pulse duration and produced by the trigger 13 under the influence of the output pulses 11 and 12.

In the weighing mode, the moments of the beginning and end of the formation of the signal and are determined by the moments of arrival of the pulses UQ and and, respectively, to the inputs S and R of the flip-flop 13.

In order to eliminate the false alarms of the control unit 18 and the false indications of the indicator 17 during inertial overruns of the weighing system beyond the rotation angles of 360 ° and 0 °, when the rotor of the selsyn sensor 2 crosses the magnetic axis of the stator, the device is equipped with contactless locking. The trigger 10 in the Weight and Zero states is blocked by simultaneously applying to the inputs I and K a pulse Ur, which by its low level fixes the required state of the trigger 10 (Fig. 2, c, d).

The blocking signal can be adjusted in phase, as well as in duration.

The indicator device 17 is blocked to a maximum by the low level of the signal Ugjj, and the signals Uj do not pass to the input of the R-flip-flop 13 (Fig. 2c).

Similarly, in the state Zero of the device 17, the pulses U do not pass through the element 11 and 11 due to the action of low levels of the pulses Ug (Fig. 2, d).

The nature of the occurrence of undamped oscillations in the zone of comparison of the device is as follows.

Irregularization of the dosing process by the trigger signal 10, as the practice of industrial operation of discrete systems shows, it is possible that the fronts of pulses coincide at the boundary

and uy,. and the slightest fluctuations,

and,

Mechanical vibrations, always present when heavy equipment is in operation at concrete mixing plants, are the cause of periodic divergence and contact of pulse fronts.

In addition, when a transistor switch controlled by trigger 10 is operated. The inductive load (electromagnetic relay) is influenced by the varying magnetizing current on the timing of switching on and off of the trigger 10.

As a result, the trigger 10 self-excited and goes into the mode of operation of the generator of continuous oscillations with a frequency of 50 Hz and above. Signals to the control unit are received with the same frequency. During self-excitation of the device in the zone of comparison, there is a failure of a stable comparison of the current value of the mass with the given one. As a result, an indeterminate state occurs, characterized by the absence of signals for both the continuation of the dosing and the end of the dosing, and the weighing cycle does not end.

The frequency selective element 19 allows to detect the occurrence of the self-excitation state of the system and to generate a signal for switching the trigger 10 to the steady state of the end of dispensing.

The frequency-selective element 19 (fig.Z) works as follows

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During self-excitation of the device in the zone of comparison, a direct sequence of rectangular pulses is formed at the direct output of the trigger 10. 5 The pulses are differentiated by elements 20 and 21. As a result, a sequence of normalized rectangular pulses is formed at the output of the inverter 22, the duration of which

10 is determined by the time constant of the differentiating circuit 20 and 21, and the repetition frequency is determined by the flip-flop frequency of the flip-flop 10. The normalized pulses through the resistor 28 and the diode 29

15 are fed to the capacitor 33. Constant; The time of this circuit is chosen so that after a time of about 3 seconds the capacitor 33 locks to a voltage that after amplification by the emitter follower 30-32 turns out to be equal to the trigger voltage of the inverter 25. The logical zero from the output of the inverter 25 is supplied at the same time the inputs of inverters 23 and 24. A logical unit from the output of inverter 24 translates trigger 10 for the installation input to the state corresponding to the termination of the weighing mode

30 A logical unit from the output of the inverter 23 through a resistor 26 and a diode 27 performs a constant charge of the capacitor 33, which allows you to continuously confirm the signal of the unit

35 at the input of the inverter 25 and, in order to permanently fix the trigger 10 in the weighing end state. Return element 19 is reset to the initial state by opening the transistor key 34 by a signal from the third output of the control unit 18. In this case, the capacitor 33 is quickly discharged, the zero signal is restored at the output of the inverter 23, and the charging of the capacitor 33 is stopped. Diodes 27 and 29 serve to isolate the signals of charge and charge of capacitor 33,

In addition to the continuous oscillations of the clock 50 toto 50 Hz and Bbmie, arising 1x

under certain conditions at the boundary of comparison, in the device there are natural oscillations with a frequency of 0.8-2 Hz, due to the reaction of the weakly-damped weighing system to the shock flow of the component being weighed. The frequency-selective element 19 provides formaro7

signal at its output at an input signal frequency of 50 Hz and higher, but does not respond to low-frequency signals of 0.8-2 Hz.

If the frequency of the following rectangular pulses from the trigger 10 is 0.8-2 Hz, then the normalized pulses with the same frequency go to the capacitor 33, which does not have time to be charged before the threshold voltage of the inverter 25. The trigger 10 is not blocked in the zone of comparison, allows one to estimate the static state of the device (the weighed mass) after calming down the weighing system and to finish weighing with the required accuracy.

Thus, the frequency-selective element 19 performs the function of eliminating the consequences of continuous oscillations during self-excitation of the device, thereby ensuring an increase in the reliability of its operation.

Claims (1)

Invention Formula Dosing device according to avt.S. No. 673861, distinguished by T1 e e with the fact that, with the aim of raising 558698 In terms of measurement reliability, a frequency-selective element, consisting of a differentiating circuit, five inverters, two resistors, two diodes, a charging capacitor, an emitter follower, is introduced into it, in the form of two transistors and a resistor and a transistor switch, and the direct output of the 1K-trigger is connected 10 with the input of the differentiating circuit, the output of which through the first and second inverters and the first resistor are connected to the anode of the first diode, the cathodes of both diodes are combined and connected to the positive input of a charging capacitor, the input of the emitter follower and the emitter of the transistor switch, the collector of which is connected to the negative charge input 0 capacitor, and the base - with the third output of the control unit, the output of the emitter follower is connected to the input of the third inverter, the output of which is connected to the inputs of the fourth and fifth inverters, the output of the fourth inverter is connected to the installation input of the TK-trigger, and the output of the fifth inverter through the second - a resistor connected to the second anode 0 diode. five J FIG. one