DD233057A3 - ARRANGEMENT FOR THE SETPOINT PROCESS FOR A QUANTITY-PROPORTIONAL DOSING DEVICE - Google Patents

Abstract

The invention relates to an arrangement for target value specification for a quantitative proportioning metering device and allows the exact addition of a metering agent in vorwaehlbaren Mengenverhaeltnis to an independent component. The object of the invention is to provide a simple, low-effort arrangement for automatic setpoint input for a discontinuously operating, accurate metering device, including manual adjustment for different quantitative ratios between dosing agent and independent component. The setpoint value used as the default value for the backward counter of a nominal / actual value control is generated before the dosing process with the aid of a digital multiplier by product formation from the quantity value of the independent component and a dosing factor selected in a multiplex manner. Fig. 1

Description

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The calculation of the dual setpoint value i _K 2 is carried out by a digital multiplier which processes on the input side the digital quantity value m _K i of the independent component as well as the dosing factor C selected by a multiplexer. The settling time of the constantly conveying metering member thus results from the quotient of the calculated target value and the frequency of the measured value pulses according to relationship (2):

t. = ^X K2 , _o , em rs- (2)

K2 ΐ · "- Switch-on time of the dosing device

S X Ii

fg2 - Frequency of the measured value pulses of the dosing unit Is

embodiment

In the drawing, the invention is shown for example. It shows:

Fig. 1 - Block diagram of the metering arrangement for a liquid

The elements 1 to 7 represent the actuating and drive level of the dosing, consisting of the pipe 1 for the dosing, the metering pump 2 with electric motor drive 3, a confirmed via magnetic actuator 5 check valve 4 to avoid uncontrolled outlets and a pulse generator for the actual value , which is installed in the form of a flow meter O ₁ or rotary encoder 62 on the pump drive. The performance implementation of the.

ON / OFF command for the drives 3.5 is the level converter 7th

Before the actual dosing process causes a transfer signal 19 from the system control the storage of the digital quantity value 18 of the independent component (mKi) in a digital latch 9. The quantity 18 is subsequently brought by a decoder 11 in the required dual encryption and the input of a digital multiplier 12 led. The second multiplication factor (C) is in dual encryption at the output of a digital multiplexer 10 which selects one of η dosing factors (C) 17 and turns on depending on the address set at a preselection rotary switch 8. The multiplier 12 forms the product according to relationship (1) and thus feeds the presetting inputs of the subsequent dual reverse counter 14.

This takes over the result of the calculation, after the delay of the duration of the computing time delayed by a digital delay element 13 transfer signal 19, the set input of the counter 14. The metering process is initiated by the arrival of a start signal 20 from the system control, in that this signal causes the setting of an RS flip-flop 15 whose output is connected to the level converter 7. The flow of dosing causes a pulse train at the actual value transmitter 61 or 62. This passes through an AND gate 16, which acts as a gate circuit by the connection of its second input to the output of the RS flip-flop 15, to the counting input of the backward counter fourteenth

The counting is aborted with the occurrence of the carry pulse, since the counter output is connected to the reset input of the RS flip-flop 15 and this tilts to its initial position.

Thus, the control command for the drives 3.5 zero and the dosing is completed.

Claims (1)

Invention claim: 1. Arrangement for setpoint specification for a quantity-proportional metering device, which automatically realizes a discontinuous presetting of a counter contained in a setpoint-actual value control using digital electronic components with gradual adjustability of a quantitative ratio between dosing agent and an independent component, characterized in that a takeover signal ( 19) to the inputs of a digital delay element (13) and a digital latch (9) is guided and the acquisition of the data input of the digital latch (9) applied digital quantity value of an independent component (18) causes, wherein the amount value (18) the pre-circuit of the output of the digital latch (9) is dual-encoded with the input of a decoder (11) in the latter and subsequently reaches the input of a digital multiplier (12), which by product formation with de m at the second input output value of a digital 1 from η - multiplexer (10), which selects one of the data inputs to its input, dual coded dosing factors (17i to 17 _n ) by interconnecting its address inputs with the outputs of a preselection rotary switch (8), the default value for a subsequent down counter (14) whose set input is connected to the output of the digital delay element (13) generates. For this 1 page drawing Field of application of the invention The invention relates to a circuit arrangement for setpoint specification for a quantitative proportioning metering device, which allows the metered addition of a component in the predetermined adjustable ratio to an independent component. Such dosing processes occur mainly in process engineering plants of the construction, chemical and food industries, but also in other industries. A typical application is the addition of additives in concrete processing plants, where an exact addition of concrete liquefiers depending on the amount of cement used in the concrete recipe is desired. Characteristic of the known technical solutions For metering emer liquid component methods are known, which generally require a setpoint specification by the operator. They are based either on the principle of time-dependent quantity control (eg DE-OS 2353220) or require a digital system for processing pulse-shaped actual-value signals with the aid of counting stages (eg DD-WP 95118). DD-WP 123843 presents a solution for the pneumatic control of a given flow or volume ratio for one independent and several dependent components. In this case, pulse sequences of the measured values are counted in a specific unit of time and compared by subtraction, so that as a result of this operation, a D / A converter generates the control command for the actuator of the dependent component. This arrangement is suitable for the regulation of a continuous flow rate, but can not be immediately transferred to a simple discontinuous metering process for a component. The scope of this solution is also limited by the use of pneumatic switching elements and the resulting high cost. Furthermore, arrangements for setpoint input are known, which make a conversion into analog variables for setting reference data in digital systems and perform the comparison of these variables using comparators (for example, DE-PS 3136581 A1). Significant disadvantages, however, are the limited accuracy of the analog measured value processing, the poor reproducibility of the measured value setting via voltage dividers and the high outlay for the A / D conversion of measured values. DD-WP 139982 describes a digital setpoint encoder system that allows the simultaneous assignment of several setpoints to a digital multi-digit measured value. However, the invention reveals disadvantages with regard to the manual setting of the setpoint values by means of switches and with regard to the necessary processing of the measured value of the actual value to a multi-digit digital value. Object of the invention The object of the invention is the realization of a simple, low-effort arrangement for the automatic setpoint specification for a discontinuously operating, quantity-proportional metering device, including a manual setting option for different quantity relations between a dependent and an independent component. The circuit arrangement is intended to create the prerequisite for a high accuracy of the metering device using digital electronic components. Explanation of the essence of the invention The invention has for its object to provide a circuit arrangement for setpoint specification of a discontinuous metering device for a dependent component, the metered amount is automatically determined by the volume of a second independent component, wherein the quantitative ratio for the use of different dosing is manually adjustable. The setpoint to be formed is preferably encrypted in dual code, so that it serves as a default value for an integrated within a setpoint actual value control down counter, which is clocked by the pulse-shaped actual value signal and whose carry signal causes the shutdown of the metering. According to the invention the object is achieved in that the before the dosing to be determined setpoint according to relationship (1) calculated from the quantity of the independent component and a factor taking into account the proportionate dependence of the dosing agent and a plant-specific constant of the transmitter: i _K 2 = Cm _K i (1) It means: i _K 2 number of pulses of the quantitative measurement of the dosing m _K i mass of the independent component C-Summarized Dose Factor