JPH0219700Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a quantitative liquid supply control device that reduces the water hammer phenomenon that occurs when the control valve is closed, especially in batch control where a fixed amount is shipped from a dispensing tank using a pump. .

An example of a conventional quantitative liquid supply control device of this type is shown in FIG. 1, and will be described. The quantitative liquid supply control device 1 is provided with a setting device 2 for setting a main batch amount such as a shipping amount, a setting device 3 for setting a pre-batch amount that is a constant remaining amount with respect to the main batch amount, and further includes a setting device 2 and a setting device. a signal processing circuit 6 to which the main batch setting signal S ₁ and pre-batch setting signal S ₂ respectively given from the flow meter 4, a flow rate measurement signal detecting the flow rate flowing into the piping 5 from the flow meter 4, and a starting signal S ₃ are input; is provided.

From the signal processing circuit 6, a main batch signal and a pre-batch signal are given to a pump sequence circuit 8 via a signal line 7 in correspondence with each of the above-mentioned set amounts, and are transmitted to a starter 10 via a transmission line 9 to operate a pump 11. let On the other hand, signal processing circuit 6
From there, a main batch signal and a pre-batch signal are transmitted to a control valve 13 via a transmission line 12 to control its opening and closing.

A pump 11 is connected to the pipe 5 from the discharge tank 14.
A fluid is sent under pressure, and after the flow rate of this fluid is measured by a flow meter 4, it is shipped from a loading arm 15 via a control valve 13, or transferred to a receiving tank 17 via a branch pipe 16. .

The operation of the conventional example configured as above will be explained with reference to a time chart in FIG.

First, a main batch amount and a pre-batch amount, which are predetermined quantitative shipment amounts, are given to the quantitative liquid supply control device 1. Next, the pump 11 is started at time point X by the main batch signal C synchronized with the starting signal _S3 , and at the same time the control valve 13 is half-opened. After this, a logic circuit in the signal processing circuit 6 determines a certain time T determined by the main batch setting amount, pre-batch setting amount, flow rate operation conditions, etc.
A pre-batch signal B is generated at a time point u when the pre-batch amount has elapsed or exceeded a certain amount, and the control valve 13 is actuated thereby to fully open the control valve. Furthermore, at the time point V when the difference between the initially set main batch amount and the pre-batch amount is reached, the pre-batch signal B is turned off, and the control valve 13
The valve opening degree is set to half open, and when the main batch amount is reached, the control valve 13 is rapidly closed and the pump is stopped at the same time to complete shipping.

In the above conventional example, as shown in Chart A in Figure 2, by using the main batch signal and pre-batch signal, the valve is controlled in stages by half-opening and fully opening the valve, and the valve is controlled by the water hammer. However, since the control valve is closed and the pump is stopped at the same time by the main batch signal, this is especially true when a gear pump is used, when piping is long, or when there is a large flow rate. It has the disadvantage that water hammer cannot be effectively reduced, and furthermore, it causes an overshoot with respect to the main batch amount, resulting in a quantitative error.

In the present invention, the pump is stopped by a pump stop signal corresponding to a pump stop setting amount that has a certain relationship with the pre-batch setting amount in the metered liquid supply control device.
After that, the control valve can be closed by the main batch signal, thereby effectively reducing water hammer, making overshoot less likely to occur with respect to the main batch amount, and reducing quantitative errors.

Next, we will discuss the third quantitative liquid supply device based on this invention.
This will be explained using figures. In FIG. 3, the same parts as in FIG. 1 are given the same reference numerals and their explanations will be omitted.

The quantitative liquid supply control device 18 is provided with a setting device 2 for setting the main batch amount and a setting device 3 for setting the pre-batch amount, which is a constant remaining amount with respect to the main batch amount, as in the conventional device, and these setting signals
S ₁ and S ₂ are input to a preset circuit 20.
The preset circuit 20 includes a preset counter section 20a in which the main batch amount is set, a preset counter section 20b in which the prebatch amount is set, and supplies a main batch signal G and a prebatch signal F to the control circuit 19. In addition, a setting device 22 is added which sets a constant ratio to the pre-batch setting amount and supplies a pump stop setting signal _S4 to the pump stop preset circuit 21. The pump stop preset circuit 21 is connected to the transmission lines 23 and 2 from the preset counter section 20b.
4, a count start signal and a flow rate measurement signal for a preset counter of a preset circuit 21 are supplied to the control circuit 19, and a pump stop signal E is supplied from a pump stop preset circuit 21 to the control circuit 19.

From the control circuit 19, signals corresponding to the main batch signal for starting the pump and the pump stop signal for stopping the pump are given to the pump control circuit 26 via the transmission line 25, and the output is used to drive the motor 27. The pump 11 is driven through the pump.

On the other hand, a main batch signal and a pre-batch signal are transmitted from the control circuit 19 to the control valve 1 via the transmission line 12.
3 and controls its opening and closing.

Although the case has been described in which the main batch setting amount, pre-batch setting amount, and pump stop setting amount are set inside the quantitative liquid supply control device 18, these setting amounts can also be set from the outside.

The operation of the present invention constructed as described above will be explained with reference to a time chart in FIG.

First, as in the conventional case, the main batch amount and pre-batch amount corresponding to a predetermined fixed amount shipment amount are given to the quantitative liquid supply control device 18. Furthermore, in the present invention, a pump stop setting amount, which is a constant ratio P to the pre-batch setting amount, is also set in advance.

Next, the main batch signal G synchronized with the start signal S ₃
As a result, the pump 11 is activated at time point X, the control valve 13 is also opened at the same time, and the flow starts flowing in the pattern shown in D. This example shows the case where the initial speed limiting function is added, so the initial speed is constant at the limited flow rate shown by _Q1 , and when a certain time T determined by the main batch setting amount, pre-batch setting amount, flow rate operation conditions, etc. has elapsed or the constant initial speed is reached. At the time point u when the limit amount is exceeded, the pre-batch signal F is added and the steady flow rate _Q2 is reached. After flowing in this state for a certain period of time, the pre-batch signal F is turned off at a time point v when the difference between the initially set main batch amount and the pre-batch amount is reached, so that the flow rate slows down from the steady flow rate _Q1 to the initial speed limited flow rate _Q1 . At the same time, preset circuit 2 at time v
After a counting start signal is given to the preset counter of the pump stop preset circuit 21 from 0 via the transmission line 23, the flow rate signal starts counting via the transmission line 24, and the count value is determined as the pre-batch setting amount and the pump stop setting. At a time point Z when the difference from the pump stop setting amount given by the signal _S4D is reached, a pump stop signal E is issued to stop the pump. After this, at the time y when the main batch signal G turns off, the control valve 1
Close 3.

The setting ratio P between the pre-batch setting amount and the pump stop setting amount is determined depending on the actual work site conditions such as the length of the piping, the laying condition of the piping, the properties of the fluid, the type of pump, or the maximum flow rate. It is empirically determined to be the optimal value.

Although the ratio P is determined in relation to the pre-batch setting amount and the pump stop setting amount, it can also be determined in relation to the main batch setting amount and the pump stop setting amount.

The configuration and operating conditions of the present invention as described above produce the following effects.

The pump is stopped by the pump stop signal, and the control valve is closed by the main batch signal.
Since the pump operation and valve operation are separated, it is possible to select the optimal condition that suits the site situation, preventing accidents caused by water hammer and improving shipping efficiency.

Since the pump stop signal is determined based on the correlation with the pre-batch setting amount, the pump can automatically operate in the optimum condition.

Since the pump stop signal can be issued before the main batch signal, it is effective in preventing overflow.

When a gear pump is used, the control device for ensuring a minimum flow rate is small-scale, which reduces costs and also helps prevent motor overload.

As described above, the present invention has features and effects not found in conventional devices, and has extremely large industrial benefits.

[Brief explanation of the drawing]

FIG. 1 is a configuration example of a conventional fixed-rate liquid supply control device, FIG. 2 is a time chart for explaining the conventional example of FIG. 1, and FIG. 3 is an embodiment of the fixed-rate liquid supply control device of the present invention. FIG. 4 is a time chart for the embodiment shown in FIG. 2: Setting device for setting the main batch amount, 3: Setting device for setting the pre-batch amount, 4: Flow meter, 1
1: Pump, 13: Control valve, 18: Fixed amount liquid supply control device, 20: Preset circuit, 21: Preset circuit for pump stop, 22: Setting amount for setting pump stop amount, S ₁ : Main batch setting signal, S ₁ : Pre-batch setting signal, S ₃ : Start signal, S ₄ : Pump stop setting signal.

Claims (1)

[Scope of Claim for Utility Model Registration] A. A flow rate measurement signal, a main batch setting signal that sets a main batch setting amount that is a predetermined liquid supply amount, and a pre-batch setting signal that sets a pre-batch setting amount that is a predetermined remaining amount with respect to the main batch setting amount. is input, the pump is started in response to the start signal, and at the same time the control valve is opened by a predetermined opening degree (point X) and the main batch signal is closed when the main batch setting amount is reached (point Y). When a predetermined time or a predetermined amount is reached in response to the start signal (point U), the control valve is opened by a predetermined opening degree and when the difference between the main batch setting amount and the pre-batch setting amount is reached (V
A preset signal that closes the control valve to a predetermined opening degree at point V) and a counting start signal that notifies the second preset circuit to start counting when the difference between the main batch setting amount and the pre-batch setting amount is reached (point V). a first preset circuit that outputs a first preset circuit; a second preset circuit that outputs a pump stop signal to stop the pump when the counted value reaches the difference between the pre-batch set amount and the pump stop set amount (Z point); Liquid supply control device.