JPS6233156B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a quantitative shipping device that ships a fixed amount of fluid.

For example, when shipping a preset amount of fluid to a tank truck, etc., the flow rate that is being shipped is measured with a flowmeter, and when the flow rate is integrated and the integrated value reaches a preset constant value,
Shipping is stopped by closing the operation valve. In this case, if the operation valve is suddenly closed, the water pressure will rise rapidly due to the water hammer action of the fluid to be measured, which may destroy the equipment in the fluid path. From these points, the amount to be shipped is integrated, and when the value reaches the pre-batch amount, which is a certain amount less than the quantitative setting value, the so-called batch amount, the operating valve is gradually closed to a half-open state, and then the batch amount is increased. The current practice is to completely close the valve when the temperature is reached.

Although such control can prevent the water hammer phenomenon, due to the delay in the response of the operating valve, slightly more than the fixed amount, that is, the batch amount, will be shipped, that is, overshipment will occur. In order to prevent such overshipping, it has been proposed to ship the correct amount by anticipating the overshipment amount and subtracting the overshipment amount from the batch amount in advance to set the set amount. . However, in this case, if the shipping batch amount is changed or the flow rate changes due to fluctuations in the discharge pressure of the pump that sends the fluid, the overshipment amount will change. Therefore, it is difficult to determine the optimal overshipment amount and subtract in advance a value corresponding to that amount from the batch amount. Further, the operation valve is gradually closed from the fully open state to a half open state, but if the valve opening at that time changes, the overshipment amount also changes. If the flow rate is controlled using a flow controller, the flow rate when the valve is gradually closed, the so-called slowdown flow rate, will be kept constant, but even if the flow rate is the same, if the opening degree of the valve is different, the overshipment amount will change. There were some shortcomings.

The purpose of this invention is to accurately prevent over-shipping even if the flow velocity of the fluid to be shipped changes or the opening degree of the valve during slowdown is different, and to make it possible to carry out accurate fixed-quantity shipping. Our objective is to provide quantitative shipping equipment.

According to this invention, the shipping flow rate at the time of slowdown is detected, and the valve opening degree of the operation valve that controls the shipping amount is detected, and from these shipping flow rate and valve opening degree, and further the response speed of the operation valve. Predict and calculate overshipment amount. The calculated overshipment amount is subtracted from the quantitative set value, that is, the batch amount, and the subtracted value is compared with the integrated value of the shipment amount, and when the two match, a full close command is issued to close the valve. be made into In this way, even if the flow velocity changes,
In addition, even if the valve opening changes at that time, the overshipment amount is predicted by taking into account the response speed of the operating valve, and the amount subtracted by that amount is used as the batch amount, so it is possible to always ship the correct amount of quantity. becomes.

Next, a quantitative shipping device according to the present invention will be explained with reference to the drawings. Figure 1 is a time chart showing the flow rate set value, valve opening degree, and actual flow rate of the quantitative shipping device.When shipping starts at time _t0 , the flow rate set value given to the flow rate controller is shown in Figure 1. As shown in A, it rises at a certain slope from time t ₀ to a constant value q. Along with this, Figure 1B
As shown in , the output of the controller, that is, the opening degree of the operating valve changes in accordance with this flow rate setting value. Also. The flow rate of the fluid shipped when the valve is controlled in this manner varies according to the output of the controller as shown in FIG. 1C, and the fluid is shipped at a constant flow rate q in a steady state.

This shipped fluid is integrated and shipped amount Q = ∫q
(t) dt is measured. When this shipping amount Q reaches the pre-batch amount, which is a certain amount less than the fixed quantity setting value, that is, the batch amount, the flow rate setting value is gradually lowered from time t ₁ as shown in Figure 1A. and therefore the valve also gradually closes,
The flow rate also decreases, and when the set flow rate q' is reached, the valve becomes half-open. In this state, when the integrated value Q of the shipping flow rate reaches the batch amount, a cutoff command, that is, a fully closed command is issued at time _t2 , the flow rate set value becomes zero, and the output of the controller also becomes zero. However, due to the response delay of the control valve, it took △Q
This is the excess shipment amount △
It becomes Q. If the time from time t ₂ to full closure is Δt, the overshipment amount ΔQ will be approximately 1/2q'Δt.

FIG. 2 shows an example of a quantitative shipping device according to the present invention, but first, parts corresponding to the conventional device will be explained. A flow meter 12 is attached to a flow path 11 through which fluid to be shipped flows, and an operating valve 13 is attached downstream of the flow meter 12 to control the flow rate to be shipped. The flowmeter 12 outputs a pulse corresponding to the fluid flow rate, which is supplied to an integrating circuit, for example, a counter 14, which integrates the flow rate. The integrated value of the shipping flow rate in the counter 14 is compared with the set value from the quantitative setting circuit 16 in the comparator 15. The batch amount setter 17 stores a quantitative setting value, that is, a batch amount, and a value that is a certain amount smaller than the batch amount, that is, the amount shipped until a slowdown command is issued, the so-called pre-batch amount. It is stored in the amount setter 18.

The control circuit 19 is given a start signal, a signal from the comparator 15 when the shipping flow rate reaches a set pre-batch amount, or a signal when the set batch amount is reached, and controls the control circuit 19. For example, a flow rate set value as shown in FIG. 1A is created in the flow rate setter 21 under the following conditions. This flow rate set value is supplied to the flow rate controller 22. One hand flow meter 12
The pulses are converted by the frequency-current converter 23 into an analog signal corresponding to the pulse frequency, that is, the flow rate, that is, a flow velocity signal, and then supplied to the controller 22. The difference between the flow rate signal inputted by the controller 22 and the flow rate set value from the flow rate setter 21 is taken,
Calculations such as proportional and integral calculations are performed based on the difference, and the output of the controller 22 is given as a control signal for the operation valve 13, and this control signal becomes as shown in FIG. The flow velocity is as shown in FIG. 1C. The valve opening degree of the operation valve 13 is determined by the controller 2.
This corresponds to the output of 2.

The above is an example of the operation of a quantitative shipping device using a conventional controller. In this invention, a setter 24, an overshipment amount calculator 25, an AD converter 26, and a subtracter 27 are newly added to the quantitative shipping apparatus described above. The valve response speed of the operating valve 13 is set in the setting device 24 . This valve response speed is a constant that is determined once the control valve 13 to be combined with the controller 22 is determined, and is set as, for example, the response time T required for the operating valve 13 to fully close from fully open. The overshipment amount calculator 25 includes the flow rate signal from the frequency/current converter 23, the valve opening output of the controller 22, and the setting device 24.
The valve response speed is input, and the overshipment amount ΔQ is calculated. If the flow velocity at the time of slowdown is q', and the value corresponding to the valve opening degree which is the output of the controller 22 is V, the overshipment amount ΔQ can be determined by the calculation TVq'/K. Here, K is a correction constant.

Next, the operation will be explained. First, when the integrated value of the counter 14 that integrates the shipping amount reaches the pre-batch amount (t ₁ ), the comparator 15 detects this and transmits this to the control circuit 19 as a comparison output. Control circuit 1
9 issues a deceleration command to the flow rate setter 21 to reduce the valve opening based on this comparison output. After the flow velocity of the fluid is decelerated by this deceleration command and sufficient time is taken for it to reach a constant flow velocity q', the overshipment amount calculator 25
A calculation command is issued to calculate the overshipment amount △Q. When this calculation is completed, the control circuit 19 issues a subtraction command to the AD converter 26 to take in the overshipment amount ΔQ and output it to the subtracter 27. In response, the AD converter 26 The amount ΔQ is converted into a digital amount in the setting unit of the quantitative setting value of the batch amount setter 17 and sent to the subtracter 27. The subtracter 27 subtracts the overshipment amount ΔQ from the quantitative setting value Q of the batch amount setter 17 to obtain a corrected quantitative setting value, and outputs this to the comparator 15. The comparator 15 compares this corrected fixed quantity setting value (Q-△Q) with the integrated value of the shipment amount from the counter 14, and when the two match, the operation valve 1 is
3 is output to the control circuit 19.
The control circuit 19 outputs a control signal to turn off the switch 20 inserted into the output side of the controller 22, thereby turning off the operation valve 13. In this case, the deadline command will be issued at time t _{2 '} , which is shifted from time t 2 in FIG. 1A to time _{t 1 by} the time corresponding to ΔQ (FIG. 1C).

In this case, the fully closed command is generated when the integrated flow rate reaches the value obtained by subtracting the overshipment amount △Q from the quantitative set value Q, and the actual shipped amount is extremely close to the set value Q, reducing the overshipment amount. can be reduced.

In FIG. 2, each part is configured as a separate circuit, but the quantitative shipping device can also be configured using a so-called microprocessor.
An example is shown in FIG. That is, in FIG. 3, parts corresponding to those in FIG. The bus 32 includes a read/write memory 33 used for temporarily storing data required for calculations, and a program memory 34 storing programs for performing various processes necessary to operate this device. Connected. Furthermore, a digital input circuit 35 is connected to the bus 32 for inputting the values of the batch amount setting device 17, the pre-batch amount setting device 18, and the valve response speed setting device 24. The output side of the flowmeter 12 is connected to the bus 32 through a pulse input circuit 36, and the constants necessary for setting the flow rate shown in FIG.
For example, each set value is set by a variable resistor, and each setting value is input to AD through an analog input circuit 38.
The signal is supplied to a converter 39 where it is converted into a digital signal and sent to the bus 32. The microprocessor 31 takes in these setting inputs and flow rate inputs, performs comparison operations, calculations of flow rate set values, proportional integral calculations, and calculations of overshipment amounts in the same manner as explained in FIG. A control signal for the operation valve 13 obtained from the calculation result is transmitted through the bus 32.
The control signal, which is output to the DA converter 41 and converted into an analog signal, is supplied to the switch circuit 43 through the analog output circuit 42. The switch circuit 43 is controlled by the processor 31 to control whether or not the output of the analog output circuit 42 is supplied to the operating valve 13. In FIG. 3, various settings can be made in either digital format or analog format.

Furthermore, in the embodiment shown in FIG. 3, the comparison between the set flow rate and the measured flow rate can be easily realized by a program.

As described above, according to the present invention, the overshipment amount is predicted and calculated based on the flow rate signal, the valve opening signal, and the response characteristic of the operating valve, and the overshipment amount is subtracted by that amount to perform fixed shipment, so that the pump discharge pressure can be adjusted. Even if there are fluctuations or changes in flow rate, the overshipment amount will not change from shipment to shipment, making accurate quantitative shipment possible. Further, unless the characteristics of the operating valves to be combined are different, no adjustment is required to adjust the overshipment amount. Note that the controller 22 is not necessarily required. This can also be omitted. By using this flow rate controller, it is convenient to be able to control the flow rate to a constant value.

[Brief explanation of the drawing]

Fig. 1 is a time chart showing the relationship between flow rate set value, controller output, and flow rate, Fig. 2 is a block diagram showing an example of a quantitative shipping device according to the present invention, and Fig. 3 is an example in which the present invention is implemented using a microcomputer. FIG. 11: Shipment fluid flow path, 12: Flow meter, 13:
Control valve, 14: Shipping amount integration counter, 15: Comparator, 16: Quantitative setting circuit, 17: Batch amount setting device, 18: Pre-batch amount setting device, 19: Control circuit, 21: Flow rate setting device, 22: Controller , 23: Frequency current converter, 24: Valve response speed setting device, 2
5: Overshipment amount calculator, 26: AD converter, 27:
subtractor, 31: microprocessor, 32: bus, 33: readable/writable memory, 34: program memory, 35: digital input circuit, 36:
Pulse input circuit.

Claims (1)

[Claims] 1: an integrating means for integrating the flow rate of a pipe line through which the shipping fluid is fed; a quantitative setting means for setting the shipping amount of the shipping fluid and a pre-batch amount that is a predetermined amount smaller than the shipping amount; and detecting the flow rate of the shipping fluid. and an adjusting means that receives a flow rate set value from a flow rate setting device and an output of the flow rate detecting means and adjusts a valve opening degree of an operating valve provided in the pipe line so that the flow rate set value is reached. and a valve response speed setting means for setting the response speed of the operation valve, and a calculation command from the output of the flow speed detection means, the valve opening output of the adjustment means, and the response speed set by the valve response speed setting means. an overshipment amount calculating means for calculating a predicted value of the overshipment amount in response to a subtraction command; a subtraction means for calculating a corrected quantitative setting value by subtracting the overshipment amount from the shipment amount in response to a subtraction command; Comparing means compares the integrated value counted by the integrating means and outputs a first comparative match output, and compares the corrected quantitative setting value and the integrated value counted by the integrating means and outputs a second comparative match output; In response to this first comparison coincidence output, a predetermined deceleration command is issued to the flow rate setting device, and in a state where the flow velocity is decelerated and stabilized by this deceleration command, the calculation command is issued to the overshipment amount calculation means, and the calculation command is issued to the overshipment amount calculation means. A quantitative shipping device comprising: a control means for outputting a subtraction command to the subtraction means when calculation of the shipping amount is completed, and further issuing a control command for controlling the operation valve to be fully closed based on the second comparison coincidence output.