SU1234727A1 - Continuous weigher - Google Patents

Abstract

The invention relates to the field of weighing equipment and can be used in the dosing of bulk materials. The purpose of the invention is to improve the accuracy of dosato for :. The device comprises a hopper 1, a feeder 2 with an electric drive 3, a mass converter 4, a mass flow setting device 5, a control action generation unit 6. The dispenser also has a device 7 for forming a time interval for outputting a given mass of material, a device 8 for decreasing the reference mass to the weighed part of the dispenser, blocks 9, 10 for comparing signals with sets of lower and upper levels of the material being monitored, block II for generating corrective action, logical device 12 and device 3 load control. The introduction of new elements and the formation of new connections between the elements of the device make it possible to eliminate the component of the error caused by the change. transfer ratio of the mass converter to the electric signal. 6 Il. CO with ho Od 4a 41 IS5 M

Description

This invention relates to a weighing equipment and is intended for use in the dosing of bulk materials.

The purpose of the invention is to improve the accuracy by eliminating the component of the error caused by a change in the transfer ratio of the converted 1 L mass into an electrical signal.

FIG. 1 shows a block diagram of the dispenser of FIG. 2; a functional diagram of the device for forming the time interval; FIG. 3 is a functional diagram of a control output unit; FIG. 4 is a functional diagram of the logic device of FIG. 5 is a functional diagram of a corrective action generating unit; FIG. 6 is a plot of the output of the weight converter.

The dispenser (Fig. 1) has a hopper 1, a feeder 2 with electric drive 3 supported on; a mass converter 4, a mass flow setting unit 5, a control action generation unit 6, the first input of which is connected to the output of the mass flow control set 5, a second input to the mass converter 4 output, and a control action output of the control generation unit 6 connected to the power 2 In addition, the dispenser has a device 7 for forming a time interval for outputting a predetermined mass of material, a device 8 for superimposing a reference mass on the weighed part of the dispenser, two blocks 9 O for comparing signals with lower and upper control signals levels of controlled mass material block I5 generate exposure correction, the logic device 12 and the load controller 13, the first and second input devices 12 are connected respectively to the outputs of the units 9 and 10 are comparison, inputs of which are connected to the output of the converter 4 weight. The first output device 12 is connected to the control input of the device 8 overlaying the reference mass, the second output of the logic device 12 is connected to the equalizing input of the device 7 forming a time interval, the third output of the logic device 12 is connected to the first control input of the corrective action generation unit 1J second manager

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the input of which is connected to the output of the time interval forming device 7, the input of which is connected to the output of the mass flow setting unit 5. At the same time, the output of the corrective action generation unit 1J is connected to the third input of the control action generation unit 6.

The dispenser also contains a load control device 13.

The dispenser works in the following way.

The material to be dosed from the hopper I is fed to the production line by the screw of the feeder 2, the rotation speed of which is proportional to the size of the signal taken from the output of the control output 6. Unit 6, on the basis of information received at the first, second, and third inputs, respectively, from the mass flow adjuster 5, the converter 4, and from the corrective action generating unit 1, generates a control signal that is fed to the input of the electric drive 3 and ensures the equality of the current value mass flow rate of the material being metered at the dispenser outlet to a given value by the setting unit 5 mass flow rate.

In the process of unloading the bunker 1, when the amount of material in it is equal to the lower level U (Fig. 6) of the controlled mass, which is set by the setter of the comparison unit 10, a output from the output of the unit 10 is supplied to the first input of the logic device 12, on the basis of which the logical device 12 forms a command: signal. At the same time, from the first output of the device 12, a command signal is fed to the input of the device 8, which imposes a superimposed reference mass on the weighed part of the dispenser. The magnitude of the reference mass is proportional to the difference between the upper and lower levels of the controlled mass in the dispenser bunker. From the second output of the logic device 12, the command signal is fed to the control input of the device 7 forming the time interval. At the output of the device 7, after the interval of time required for the issuance of a given mass of material for a given amount of its flow, a command signal is generated, which is fed to

the second control input of the unit 11 is a correction action. The first control input of the unit P receives a command signal from the third output of logic device 12, but only if the amount of material in the bunker 1 (with regard to the attached-reference mass) reaches the lower level of the controlled mass determined by the setting unit 10 compare. If the command signals from the outputs of the device 7 and the logic device 12 arrive simultaneously at the first and second control inputs of the block P, then the output of the block M does not change the signal. If the signal from the output of logic device 12 arrives at the first control input of block II with delay or advance of the signal that comes from the output of device 7 to the second control input of block II, then the output of block II changes the generated corrective action and, acting on the third the input of block 6 ensures the elimination of the component of the metering error caused by the change in the transfer coefficient of the mass converter 4.

In addition, when the amount of material in the bunker I reaches (taking into account the attached reference mass), the lower level of the monitored mass nulls the command signal generated by logic device 12 and removed from its first output, resulting in the device 8 ocjratecT- removing reference mass from the weighed part of the dispenser. At the same time, the logic device 12 generates a command signal taken from its fourth output, which is fed to the input of the load control device 13, which carries out the process of loading the hopper 1 with material.

The process of loading the hopper I with the material ends when the amount of material in it reaches the upper level U, (Fig. 6) of the controlled mass specified in the comparison unit 9, the output signal of which is fed to the second input of the logic device 12-. At the same time, the command signal at the fourth output of logic device 12 is zeroed, the loading process of the hopper 1 with the material is stopped, and the operation cycle

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control system of the dispenser is repeated. The control action generation unit 6 (Fig. 2) consists (embodiment) of adder 6.1, the first and second inputs of which are connected to the first and third inputs of block 6, and the output is connected via switch 6.2 to the integrator input 6.3 and the first input of adder 6.4, The second and third inputs of which receive signals from the outputs of the correction block 6.5 and the low-pass filter 6.6 with long-term memory, respectively. The output of the adder 6.4 is connected to the output of block 6. The inputs of block 6.5 to the corrections and filter 6.6 are combined and connected to the output of the comparison element 6.7, the first input of which is connected via switch 6.2 to the output of the setpoint 6.8 of the upper level of the material mass monitored s of the metering hopper, and the second input of the element 6.7 comparison through switch 6.2 is connected to the output of the adder 6.9, the first input of which is connected to the output of integrator 6.3, and the second input is connected to the second input of block 6 and to the input of the block 6.10 signal comparison, the output of which is connected to the first control m switch input 6.2. The second input of the block 6 is also connected to the input of the block 6.1-1 of the signal comparison with the setpoint generator 6.12 of the lower level of the controlled mass. The output of the 6.1 block 1 is the comparison of signals among- .. with the second control input of the switch 6.2.

The control generation unit 6 operates as follows.

The output signal of the mass converter 4, proportional to the measured mass of the material in the hopper 1, is fed to the second input of block 6 and further to the first input of the adder 6.9 and to the first inputs of blocks 6.10 and 6.11 of the signal comparison, the second inputs of which receive signals from outputs of 3addlers 6.8 and 6.12 of the upper and lower levels of controlled mass.

In the process of unloading the bunker, when the signals of the converter 4 and the transmitter 6.8 of the upper level Uj (Fig. 6) of the monitored mass are monitored, the block 6.10 is triggered, the output signal of which goes to the first control input of the switch 6.2. This causes the switching of the 6.1 s the input of the integrator 6.3, the output of the adder 6.9 with the first input of the comparison element 6.7, the second input of which is connected to the output of the setting device 6.8.

From the output of the adder 6.1, a signal is removed that is equal to the signals from the outputs of the setter 5 mass flow rate and the block 11 for generating a corrective action, i.e. a signal proportional to the corrected value of the specified mass flow rate.

From the output of the adder 6.9, a signal is taken equal to the sum of the signals proportional to the corresponding corrected mass of material to be dispensed at the moment and the current w of the mass of material in the hopper 1.

At the output of the element 6, 7, the signals of the setpoint generator 6.8 and the adder 6.9 produce a dosing error signal, which is fed to the inputs of the correction unit 6.5 and the low-pass filter 6.6 with long-term memory. In this case, the instantaneous deviations of the mass flow at the dispenser output from its predetermined value are eliminated due to the control action taken from the output of block 6.5 and fed to the first input of the adder 6.4 and further to the input of the electric drive 3. As a result of filtering the current error value dosing by the filter 6.6 at its output produces the magnitude of the control action, which in total with the magnitude of the signal taken from the output of the adder 6.1 is fed to the input of the electric drive 3 and ensures that the average value of the flow yes mass of its given value

In the process of unloading bunker 1

when the amount of material in it is equal to the lower level U. (Fig. 6) of a controlled mass, the comparison unit 6.11 compares the signal of the mass converter 4 and the setpoint generator 6.12. Block 6.1, the operator, issues a command signal to the second control input of the switch 6.2, which breaks the connection between the output of the adder 6.1 and the input of the integrator 6.3, the output of the adder 6.9 and the first input of the element 6.7 comparison, the second input of the element 6.7 comparison and the output of the setting device 6.8 . This error

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the dosage at the output of element 6.7 becomes equal to zero, the signal at the output of block 6.5 also becomes equal to zero, and at the output of filter 6.6 the value, which in total with the signal taken from the output of the mat 6.1, ensures that the average mass flow rate at the output of the dispenser is equal to magnitude.

After the process of loading the hopper 1 with material or imposing a reference mass on the portion of the dispenser, which is determined by the logic device 12, the control action of the control output unit 6 is repeated.

The device 7 for forming the time interval for outputting a given mass of material (Fig. 3) consists of a converter 7.1 of a DC voltage signal into a frequency signal, a switch 7.2 and a counter 7.3 im-, pulses, the input of which through the switch 7.2 is connected to the output of the converter 7.1, the input of which is connected to the input of the device 7 forming the time interval. In this case, the control input of the time interval forming device 7 is connected to the control inputs of the switch 7.2 and the pulse counter 7.3, and the output of the pulse counter is connected to the output of the time interval forming device 7.

The device 7 forming the time interval works as follows.

In the process of unloading the bunker 1, when the amount of material in it is equal to the lower level of the control mass, which is specified in the comparison unit 10, the output of the logic device 12 receives a command signal to the control input of the device 7 and then to the control inputs of the switch 7.2 and counter 7.3 pulses. In doing so, the pulse counter 7.3 is zeroed out, and the switch

7.2, actuation, connects the output of the setpoint mass flow controller 5 through the converter 7.1 to the input of the counter

7.3, which starts counting pulses. The pulse counting process continues up to a predetermined number, which is set in the pulse counter and which determines the time interval for the issuance of a given mass of material at a given flow rate, followed by

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The output of the counter 7.3 generates a command signal arriving at the output of the device 7 and further, to the second control input of the corrective action generating unit 1I.

Corrective action generation unit 11 (Fig. 5) consists of a source P.1 of stabilized power, a switch 11.2 and an integrator 11.3, the input of which through the switch 1I.2 is connected to the outputs plus or minus of the source

11.1, depending on the order of arrival of commands from the first or second inputs of block 11, respectively to the first or second control inputs of switch II.2. At the same time, the output of the integrator 11.3 is connected to the output of block II.

Corrective action generation unit 11 works in the following way ..

The co-footer is connected to the first and second control inputs of the block 11 and further to the first and second control inputs.

11.2, command signals from the outputs of the interval shaping device, time, and logic device 12 are received, the first of the incoming command signals triggering the switch 11.2, which leads to the formation of a connection between the integrator input P3 and the source output 11.1, and the second causes the switch to turn off DI.2 and the gap formed by communication. In addition, if the command signal from the output of the logic device 12 arrives at the first input of the block 11 with a delay with respect to the command signal coming from the device output

7 to the second input of block I1, then the input of integrator 11.3 is connected to the output plus source 11.1. If the same command signal from the output of logic device 12 arrives at the first input of block 11 ahead of the command signal that arrives at the second input of the block. M from the output of the device 7, the input of the integrator 1.3 is connected to the output of the minus source 11.1. Depending on this, a positive or negative correction signal is generated at the output of the integrator.

In this case, the magnitude of the correction signal depends on the length of the delay period or in advance.

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Neither and from the integrator integration time constant 11.3, is the U.-. I 1 unit adjustable parameter.

c. The logic device 12 (Fig. 4) may consist of a source of direct current voltage AND, intermediate 1P-7P relays of the RES 22 type, resistors R and RJ, and capacitors C and C. JO The logic device 12 operates as follows.

In the initial state, the material in the bunker 1 of the dispenser is absent, the first and second inputs are logic, e (devices 12 signals from the outputs of blocks 9 and 10 of the comparison are not received in relays 3 and 4P are turned on. At the fourth output of logic device 12, a command 2Q is generated the signal that enters the input of the control unit 13, which carries out the process of loading the hopper 1 with material.

As the bunker 1 is filled, when 25 the amount of material in it is equal to the lower C, and then the upper (and) levels (Fig. 6) of the controlled mass, given respectively in blocks 10 and 9 of the comparison, the latter are triggered at their outputs command signals and arrive respectively at the first and second inputs of logic device 12. This turns on relay 2P and relay JP, which in turn turns off relay 3R and turns on relay 5P, after which the command signal at the fourth output of logic device 12 is zeroed and the zag process The bunker 1 stuff is terminated.

In the process of unloading the hopper 1 with the equal signal from the output of the converter 4, first the top (U). and then to the lower (U,) levels of the controlled mass, specified respectively in blocks 9 and JO, the command signals at their outputs are zeroed, which first leads to the IP turn-off off; and then the 2P relay. Turning off the 2P relay causes the 6P relay to turn on, which in turn turns on the 7P relay and turns off the 5P relay, and the 7P relay turns off the 4P relay. After performing these operations, a command signal is generated at the second output of the logic device 5 12, which is fed to the control input of the time interval forming device 7, and at the first output the logic 30

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For which device 12, a command signal is generated, which is fed to the input of the device 8, which imposes a reference mass on the weighed part of the dispenser. At the same time, the signal at the output of converter 4 increases, and when passing the bottom of the lower {U (), and then upper (C) levels of the monitored mass, it triggers blocks 10 and 9 cpais. At the outputs of blocks 10 and 9, command signals are generated and, acting respectively on the second and first inputs of the logical device 12, turn on the relay 2P. and then an IP relay, which disables the 6P relay. Disconnecting the 6P relay indicates the imposition of a reference mass on the weighed part of the dispenser.

In the process of further unloading of the bunker 1, when the signal from the output of converter 4 is equal, first to the upper (U,) and then to the lower (y) level of the controlled mass, set respectively in blocks 9 and 10, the command signals at their outputs are zeroed, which leads first off the IP relay and then the 2P relay. Turning off the 2P relay turns on the ZR relay, which turns on the 4P relay and turns off the 7P peiie. Disabling the 7P relay causes the command signals to be on the second and. the first output of logic unit 12 is zeroed out and the weighed part of the dispenser is released from the attached reference mass. In addition, switching off the 7P relay indicates the end of the process of unloading the mass of material equal to the attached reference mass, and leads, on the one hand, to the formation at the third output of the logic device 12 of the command signal sent to the first control input of the unit 11, the corrective action, and, on the other hand, to the formation at the fourth output of the logic device 12 a command signal input to the device 13 of the load control 13, performing the process of loading the hopper 1 aterialom and the work cycle (Tc, Fig. 6) of the dispenser is repeated.

Claims (1)

Invention Formula A continuous weighing dosing unit containing an electrically powered feeder, supported by a mass converter into an electrical signal, a loading control device, a control action generation unit, the first input of which is connected to the output of the mass flow setpoint device, the second the input is with the output of the mass converter into an electrical signal, and the output with the electric drive of the feeder, and two elements comparing the signals with the setting devices of the upper and lower levels of the material mass monitored, the inputs of which are connected to the output of the mass converter into the electric signal, characterized in accuracy due to the elimination of the error component due to the change in the transfer coefficient of the mass converter into the electrical signal, the device for forming the time interval, the devices About imposing a reference mass, a corrective action generating unit and a logic device, the first and second inputs of the logic device are connected respectively to the outputs of the first and second comparison elements, the first output of the logic device is connected to the input of the device for applying the reference mass, the second output is connected to the first input of the forming device the time interval, the third output - with the first input of the generation unit of a corrective action, the second input of which is connected to the output of the device forming the int The time interval, the second input of which is connected to the output of the mass flow master, the output of the corrective action generation unit is connected to the third input of the control action generation unit, and the load control device is connected to the fourth output of the logic device. i 7.1 7.2 eh oh FIG. 2 7J Mr. S I (rig 3 fsh- 71 P2 11.3 I gp FIG. five Compiled by V.Shirshov Editor L. By vkhan Tekhred L. Serdyukova KoppeicTop V. But ha Order 2977/46 Circulation 705Subscription VNIIPI GCGP State Committee. for eradication and discoveries 113035, Moscow, Zh-35, Raushsk iab., 4/5 Production and printing company, Uzhgorod, st. Project, 4 f1k. &