JPS60162094A - Liquid-feeding system controller - Google Patents

Abstract

PURPOSE:To eliminate the necessity of correcting the pump characteristic by setting the independent control condition for each pump in a liquid-feeding system control by a plurality of pumps and controlling the operation under the these independent control conditions. CONSTITUTION:When water is supplied by two pumps 4-1 and 4-2 through a water feeding pipe 9, the min. revolution speed and the set speed of each pump can be set separately by adjusting variable resistors 24 and 25 through contacts 23A and 23B, and operation can be controlled under each independent control condition. Therefore, even in the case where the revolution speed for making equal the Q-H characteristic of each pump differs, alternate intermittent operation is always secured, and the necessity of correcting the characteristic can be avoided.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a liquid supply system using a number of variable speed drive pumps, and when the number of liquid supply lids is low, especially at night, the pumps are intermittently operated. Relating to a liquid supply system that is adapted to be operated.

[Background of invention]

Pump efficiency generally reaches its maximum near the design load (full load) and gradually decreases at partial loads.

Therefore, conventionally, in systems such as water supply systems where the amount of liquid supplied fluctuates greatly and often drops to almost zero, especially at night, multiple pumps are installed, and the number of pumps in operation depends on the amount of liquid supplied. and rotation speed, and when two or more pumps are in operation, one of them
Only one pump takes on a partial load by speed control, the remaining pumps are always operated at full load, and the amount of liquid supplied is reduced so that only one pump is used at minimum load. In the operational range, systems that supply liquid through intermittent operation of one pump to save energy have become widely used.

An example of such a liquid supply system is shown in FIG.

This figure shows an example of a system that supplies water using two pumps. In the figure, 1 is a water tank, 2-1 is a water tank,
, 2-2 is a suction pipe, 3-1. 3-2.10 is a gate valve, 4-1. 4-2 is a pump, 5-1. 5-2 is a motor.

6-1 and 6-2 are check valves, 7 is a pressure tank, 8 is a pressure sensor, 9 is a water supply pipe, and 11 is a water faucet at the end.

The two pumps 4-1 and 4-2 each have a motor 5-
These motors are driven by 1°5-2.
5-2 is variable speed controlled by a control device (not shown) K including an inverter device and the like.

Figure 2 shows pump 4-1゜4-2 when driven at variable speed.
This shows an example of the operating characteristics of the water supply system.
The water supply pressure 11 is plotted on the vertical axis, and the rotational speed N of the pump is used as a parameter, and is called a Q-H% gonadal diagram.

Note that Ho is the target discharge pressure of the pump.

In this $2 diagram, 1 enzyme a is the Q-H% characteristic when the pump rotation speed is the maximum speed NMAX, and the following curves are: c,
d and e reduce the rotational speed N times sequentially from X to Nho,
N,, N,,, N・Respective Q- when closed
This shows He properties. The curve f is the Q-H% characteristic at the preset minimum operating speed NM. It goes without saying that when the motor is controlled at variable speed using the inverter device as described above, the rotational speed N of the pump can be controlled steplessly from NM to NMAXx.

Therefore, the operation of the system shown in FIG. 1 will be explained with reference to FIG. 2.
As is clear from Figure 2, when the amount of water Q being supplied to the pump decreases, the water supply pressure H changes if the rotational speed of the pump remains constant at that time, and as the amount of water Q increases, the water pressure H decreases. .

Therefore, a control device (not shown) takes in the water pressure H from the pressure sensor 8 provided in the water supply pipe 9, and when it falls below the target water pressure H6, increases the rotational speed of the pump so that the water pressure H becomes lower than the target pressure H8. When the rotation speed increases, control is performed to reduce the rotation speed to N', thereby reducing the pressure H in the water supply pipe 9.
control so that the pressure almost coincides with the target pressure H0.

Therefore, if the water supply amount Q is now Qi, the control device operates either pump 4-1 or 4-2, for example, only pump 4-1 is operated, and pump 4-2 is stopped. The rotational speed of pump 4-1 at this time is N'''
Keep tN-tHK. As the water amount Q increases from Q(towards Q-), the rotational speed N of the pump 4-1 increases.
is increased by N-x K from NMI, l, thereby maintaining the water pressure in the water supply pipe 9 at the target pressure H0. Then, when the water amount Q exceeds Q-, K starts operating the pump 4-2 while keeping the rotation speed of the pump 4-1 at NMA, and increases the water supply itQ from the rotation speed ThNM+N to NMAxK. The pressure is changed in advance so that the target pressure H0 is maintained.

Therefore, according to this system, the water supply itQ is the minimum value Q
M! Even when the water amount changes from N to twice the maximum water supply amount Q, . . . , the target pressure H0 can be maintained and water can be supplied stably.

On the other hand, in this system, the water supply amount Q is the minimum water supply amount QMI
When the pressure drops below W, variable speed control of the pump is stopped and the water supply pressure H is maintained close to the target pressure H0K by repeatedly stopping and restarting the pump, which is called intermittent operation control. . In other words, even if the water supply amount Q decreases to Qi and the pump rotational speed N is set to N in response, even if the water supply amount Q decreases further, at this time, the control device will control the rotation of the pump. K is maintained at the minimum rotational speed N,, W without reducing the speed N. As a result, the pressure H in the water supply pipe 9 exceeds the target pressure Ho and begins to rise along the curve rK. Therefore, the stop pressure H is higher than the target pressure H0 by a predetermined value.
0ff is set, and when the pressure sensor 8 detects that the pressure H in the water supply pipe 9 has reached the stop pressure H0ff, the operation of the pump is stopped, and then the pressure H is set to the target pressure Ho.
When the water pressure H in the water supply pipe 9 decreases to
The water supply operation is performed in a state where H8ff changes between H8 and H8ff.

Therefore, with this water supply system, the pump will not be operated for a long time in an extremely inefficient state, and energy saving can be achieved sufficiently.

By the way, in a system using a plurality of pumps like this, it is desirable to make the operating times of the plurality of pumps as equal as possible.

In particular, as shown in Figure 1, in a liquid supply system using two pumps, even if the maximum water supply amount can be sufficiently covered by one pump, if two pumps are used, Some systems are designed to increase reliability by allowing the other pump to maintain its water supply function even if one pump is unable to supply water due to a failure, etc., but even in such systems, two pumps are normally used. It is necessary to use the pumps alternately to avoid problems caused by leaving the pumps stopped for long periods of time.

Therefore, in the conventional water supply system described above, when controlling the intermittent operation, a control is generally adopted in which different pumps are operated alternately or j@th times. For example, in the system shown in Figure 1, pump 4
-1 is in operation, the water -mQ decreases, the water pressure H becomes H8ff, and the operation of this pump 4-1 is stopped. When the water pressure H decreases to the target pressure H0, this time, the pump 4-1
Pump 4-2 starts operating instead of pump 1.
A system having three or more pumps, in which two pumps 4-1 and 4-2 are operated alternately, such that pump 4-1 is started after pump 2 is stopped. In this case, these three pumps are started to operate one after another.

However, the Q-)i% characteristics of the pumps are not necessarily the same even if the pumps are of the same type and have the same type, and there are often variations in the rotational speeds N that exhibit the same Q-H characteristics. In other words, in Fig. 2, even if the Q-H% characteristic of the curve t is obtained at the rotational speed NMIN for the pump shown in FIG. In some cases, a Q-H% characteristic like f' or f'' in FIG. 2 may occur.

As a result, in the conventional liquid supply system using a plurality of pumps, there is a problem in that the above-mentioned intermittent operation control cannot be performed satisfactorily.

For example, assume that the Q-H characteristic of the pump is assumed to be the curve f in FIG. 2 and the minimum rotational speed NMIN is set. At this time, if the Q-H characteristic at the rotational speed N OLD of the other pump is a trap as shown by the curve f', then at this rotational speed NMIN, even if the water volume Q decreases ( Since the water pressure H does not rise to Hoff, the operation of this pump cannot be stopped.

On the other hand, in other pumps, Q- at rotational speed NMINK
If the Ht￥j characteristic is curve f", the water pressure H will turn off before the water volume Q decreases to the minimum water volume Qi.
Therefore, this pump has a shorter operating time than other pumps.

Therefore, in the conventional m=system using a plurality of pumps, it is necessary to match the characteristics of the pumps used when configuring the system, and there is a drawback that costs increase significantly due to pump selection and pump rework.

[Purpose of the invention]

An object of the present invention is to eliminate the drawbacks of the prior art described above, and to provide sufficient intermittent operation fI even if the characteristics of the pump are slightly uneven.
] The object of the present invention is to provide a control device for a liquid supply system that can exercise the lj-control function.

[Outline of invention]

In order to achieve this purpose, the invention is capable of setting independent control conditions for each valley pump in the HA system equipped with mantissa pumps, and that each pump is operated under these independent control conditions. It is characterized by the following points.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A liquid supply system control device according to the present invention will be described below with reference to illustrated embodiments.

FIG. 3 shows an embodiment of the present invention, which is connected to the liquid supply system shown in FIG. 1. In FIG. 1, 20 is an inverter device, 21 is a breaker for the main circuit, and ηA.

nB is a contactor for switching pump operation, 23A and 23B are contacts that operate in conjunction with contactors 2jA and 228, respectively.
25 is a variable resistor.

The inverter device functions to variable speed control the motors 5-1 and 5-2, and the output frequency and output voltage are controlled by a control circuit (not shown). In this embodiment, the inverter device 20 is used to control the motors 5-1 and 5-2 at variable speeds, but instead of this, a cycloconverter may be used, or the next reduction control,
Any variable speed control means such as a dilute current coupling may be used.

The contactors Z2A and 22B are each controlled by a control circuit not shown in the figure, and serve to connect the variable frequency output of the inverter device to either the motor 5-1 or the motor 5-2. Contactor 22AK is interlocked, and when contactor A closes, it closes together with it, connecting resistor 24 to the minimum output frequency setting circuit in 2C1 in the inverter system, and similarly, contact 23B is connected to contactor A. Closes in conjunction with 22B,
It serves to connect the resistor δ to the minimum output frequency setting circuit.

The variable resistors u and 25 are each configured to be adjustable to a predetermined resistance value, and when connected to the lowest frequency setting circuit on the inverter side, function to determine the lowest output frequency on the inverter side based on the resistance value. do.

Therefore, in the liquid supply system shown in FIG. 1 to which the embodiment shown in FIG.
You can configure each MIW separately, for example,
If the Q-11 characteristic at the speed NM of the pump 4-1 is like the curve f' in Fig. 2, the lowest speed can be reduced by setting the speed using the variable resistor higher than NM The Q-H% characteristic in rotational speed can be made as shown by the curve f in FIG. 2, and similarly, the minimum rotational speed NM of the pump 4-2! If the Q-1 characteristic at , is like the curve f in Figure 2, the speed set by resistor 5 should be lower than NMIW, thereby Q-1-1 at the lowest speed.
As a result, regardless of whether pump 4-1 or 4-2 is being operated,
When the water supply amount Q at that time becomes less than Qi and the water supply amount decreases further after the state of the lowest rotational speed is reached, K becomes
The stop water pressure is always Hoff when the stop water amount is Qoff, and the operation is reliably stopped and alternate intermittent operation can be obtained.

The difference in this embodiment is that only a relay and a variable resistor are added to the conventional control device.

Reliable intermittent and intermittent operation can be achieved with a slight increase in cost.

In addition, in the above embodiment, a system that has two pumps and always supplies water with one pump was explained, but a system in which two pumps are operated in parallel when the amount of water supplied increases is also applicable. Needless to say, it is applicable.

Furthermore, it goes without saying that the number of pumps is not limited to two, but can also be applied to three or more pumps; in this case, K is the number of contacts 23A and 23B and the variable resistor.

It is only necessary to increase the number of δ according to the number of pumps.

Next, FIG. 4 shows another embodiment of the invention, in which the control circuit, which was omitted in the embodiment of FIG. It is executed by a computer program, and in FIG. 4, μcon is a microcomputer (hereinafter referred to as an icon), CPU is a central VL calculation unit, Me is a memory consisting of ROM and RAM,
PIA-1-P I A-5 is input/output port, A is input terminal, 1" l-F a is interface, SWI
, SW2 is a dip switch for setting the minimum rotational speed NMIN and stop pressure H0ff, Zii stabilization electric unit C is a magnetic contactor, MCo is its contact, FB
I.

PH1 is a pushbutton switch, and the rest is the same as in FIGS. 1 and 3. In this embodiment, the contacts 23A, 23B and the variable resistor U in FIG.

Part is a little girl.

The pushbutton switch PH1 is used for starting, and when this switch is pressed, the electromagnetic contactor MC operates and the contact MCo closes, thereby causing the electromagnetic contactor NiC to self-hold and keep the switch on.

In this way, when the pushbutton switch FBI is pressed and the contact MCo is self-held, the DC' core is supplied from the stabilization percentage source unit Z to the microcomputer μcon, and the microcomputer μc
on starts operating.

The microcomputer βcon receives the water pressure H in the water supply pipe 9 from the pressure sensor 8 via the PIA-1 (input/output capo).
The minimum rotational speed NMIN is input from the dip switch SWl via PIA-4, and the input/output capo) PIA-
Stop pressure Hof from dip switch SW2 via 5
Each f is input.

Therefore, based on this data, the microcomputer μcon
Perform one process according to a predetermined program stored in the memo IJ Me in advance, and input/output capo) PI
From A-2 to the breaker 21 via interface F2
and the electromagnetic contactors 22A and 22B, and sends a control signal to the inverter iron tk via the interface F3 from the input/output capo PIA-3 to the motors 5-1 and 22B.
5-2 is performed, and the pumps 4-1 and 4-2, which are essential to the above-mentioned liquid supply system, are controlled.

On the other hand, when the push button switch PB2 is pressed while the pump is operating in this way, the electromagnetic contactor MC is restored and the contact M
Co opens. At the same time, the control of the microcomputer μcan is also turned off, and the operation of the liquid supply system is stopped.

Note that the above operation is similar to that of a known liquid supply system.

The operation when the pre-water supply Q decreases to Q4 in FIG. 2 and the intermittent operation control of the pump is entered will be explained with reference to the flowchart in FIG. 5.

When the water supply lid decreases and the routine shown in Fig. 5 is entered,
First, in steps ■ and ■, the input/output capo) PIA-3 and PIA
-2 to pump stop pressure Hoff and minimum rotation speed KNMI
N and memory areas Me10 and Mell, respectively.
Store in.

In the following step ■, it is checked which of the electromagnetic contactors 22A and 22B is closed, and the pump power 4-1 currently in operation is determined.
4-2. In addition,
Here, the Q-H% characteristic of the pump 4-1 is the curve f in FIG.
On the other hand, it is assumed that the Q-He property of the pump 4-2 is as shown by the curve f' in the figure.

When the result in step (2) is 22A, step (2) KM is continued, and the water supply pressure H'tt is fetched from the input/output capo PIA-1 and stored in the memory area Me12.

In step ①, the memory areas M e 10 and M e
12 (7) Compare the data, that is, the water supply pressure at that time and the stop pressure Hoff, and find that (H≧Hoff
), and as long as it is determined that the result is NO2, that is, the water supply pressure H at that time is the stop pressure)toffK, return to step
1 is stored in the memory area Meli.
Press N to continue operation, but the result is YES.

That is, when it is determined that the water supply pressure H at that time is equal to or higher than the stop output Hoff, the process proceeds to the next step (2), and after stopping the rotation of the pump 4-10, the process proceeds to step (2).

On the other hand, if it is determined that the pump 4-2 is being operated at that time, that is, the result of step ■ is 22B1, then the process proceeds to step ■ after passing through step ■.
be done. Then, in this step ■, the memory area Me
The data stored in ll, that is, the minimum rotation speed N
A process of adding a predetermined rotational speed n to the error and restoring is performed.

The data n added at this time is the second
In order to make the Q-H% property of the pump 4-2 shown by the curve f' in the figure to the Q-)1% property shown by the curve f, the rotational speed is adjusted to be x(llI). put.

Therefore, according to this embodiment, the minimum rotational speed of the pump 4-2 can be made higher than the minimum rotational speed of the pump 4-1 by n, and as a result, which pump is controlled to the minimum rotational speed. The same Q-H characteristics can be provided even when the engine is turned off, the conditions for stopping operation can be equalized, and alternating intermittent operation can be performed reliably.

By the way, in the above explanation, kL, Q-8% of pump 4-1
and the Q-H characteristic of the pump 4-2 is the second
The figure assumes a case where the rotation speed is shifted to the low rotation speed side,
Pump 4-2 may be used as a reference, and if the characteristics of other pumps deviate from the reference pump to the high rotation speed side, the addition of data n in step It is sufficient to subtract data n.

In addition, in the embodiment shown in FIG. 5, the minimum rotational speed of each pump is corrected for each pump.
Although the percentages are the same, the Q-Ht of each pump
+! You can leave the f property as it is and set the stop pressure H8ff separately for each pump (
Another embodiment of the present invention based on this system is shown in FIG.

The embodiment of FIG. 6 is similar to the embodiment of FIG. 5 only in that step (2) is replaced with step (2) in FIG. 5, and step (2) is omitted.

Therefore, in the case of this embodiment, when the pump 4-2 is being operated, the memory area Mel is
The content of O is lowered by a predetermined pressure, and step ■
The data in the memory area Mel+ used for judgment, that is, the stop output, is set to a different value for pump 4-1 and pump 4-2, thereby correcting the difference in Q-H% at the minimum rotation speed NMIN. Therefore, the same stopping conditions can be applied to all pumps.

In this embodiment as well, the pump 4-1 may be used as the reference, or any pump may be used as the reference as in the embodiment shown in FIG. In addition, in this embodiment, the front stop output) 10 f
Although a predetermined value is subtracted from the stop pressure Hoff of the other pump using the pump that can lower f as a reference, a predetermined value may be added based on the lower one.

By the way, in such a system, the target pressure Ho can be adjusted at the minimum water volume Qi due to changes in the water level in the water tank l shown in Fig. 1 and the coding of the pumps 4-1 and 4-2.
The minimum rotational speed NMIN for giving the following changes. In other words, the characteristic shown by the curve f in Fig. 2 may become distorted as shown by f' or f''. In this case, the setting of the minimum rotational speed should be corrected so that the target pressure Ho can be obtained at the minimum water supply amount. It is necessary to

Therefore, in such a case, K, the minimum rotational speed NM! An embodiment of the present invention in which 11 is automatically corrected and reset will be described with reference to FIG.

First, in this embodiment, a flow rate detector is provided in the water supply pipe 9 shown in FIG. 1 so that it can detect when the water supply fiQ becomes zero, and furthermore, a signal indicating that the water supply iQ becomes zero is generated. can be taken in by the microcomputer μcon K shown in FIG. Furthermore, data set in the memory area M e 13 K is used to operate the pump at the lowest rotational speed.

Next, the operation will be explained.

In FIG. 7, when the process according to this flowchart is started, the rotational speed iN of the pump at that time is taken in at the first step. For this reason, K has an input/output capo.
) It would be better to take in the output frequency command F supplied to the inverter device from the PIA-3 and calculate the rotational speed N using the following equation.

20 = -F P: Number of poles of the pump drive motor The rotational speed N thus determined is the synchronous speed,
On the other hand, since the induction motor has slippage, the actual rotational speed of the pump is smaller than N, but this is hardly a problem in practice.

In step ■, the calculated rotational speed N is changed to the minimum speed N, f,
to determine whether they are equal or not.

Then, while Irai is NO, it returns to the step [stock], and only when it becomes YhiSIC, it goes to the step OK.

In step ■, the output signal of the flow rate detector is taken in, and in the following step ◎, it is determined whether the flow rate is zero.
While the result is NO, return to step @, and proceed to step [phase] only when the result is YES.

In step [phase], the fetal fluid pressure H in the water supply pipe 9 is taken in from the pressure sensor 8, and in the following step (2), it is determined whether the pressure (1) is equal to the target pressure. And (1(=Ho
), proceed to step ■, set the data N at that time as the minimum rotational speed NIIIN, and write the memory area M again.
e13, and the processing according to this flowchart ends.

On the other hand, if the result in step (2) is NO, that is, the condition (H=Ho) is not established at the rotational speed N at this time, the process proceeds to step [stock] and performs the process described below. That is, when proceeding to this step, the microcomputer μcon changes the setting of the minimum rotational speed NMIH according to the relationship between the pressure H and Ho at that time, and (H)
When (Ho), the set values of NM and N are slightly decreased, and when (H(Ho)), the set values of NilIN are increased little by little.As a result, (
H = Ho ), that is, the result in step (2) is YES.

Then, when the result in step ◎ becomes YES, the rotational speed iN at that time is set as the new minimum rotational speed NMIN in the memory area Me13, so in the end, in this embodiment, the pump Q-8% Even if the characteristics change, the minimum rotational speeds UN and lrx are always newly set accordingly, and the minimum rotational speed NMIM corresponding to the Q-H characteristic that passes the target output hO at the minimum water supply amount Qi is maintained accurately. I can do it.

In the above embodiments, the liquid supply system using two pumps has been described, but it goes without saying that the present invention can be applied even when the number of Hondas is two or more. Needless to say, the same thing applies to a system in which the pumps are operated simultaneously.

〔Effect of the invention〕

As explained above, 1. Thus, 5. according to the present invention, even if there is a nest of continuous rotations in order to make the Q-He characteristics of each pump the same in a pump supply system using a number of pumps, Since it is possible to always and reliably carry out the complete intermittent VC rotation, the drawbacks of the conventional technology are eliminated, and there is no need for characteristic packing such as pump selection or impeller processing, resulting in stable flow at low cost. Therefore, it is possible to easily provide a control device for a liquid supply system that can be easily manufactured.

[Brief Description of the Drawings] Figure 1 is a block configuration diagram showing an example of a liquid supply system using two pumps, Figure 2 is a characteristic curve diagram showing an example of pump #B, and Figure 3 is a diagram of the present invention. FIG. 4 is a block diagram showing another embodiment of the control device, FIG. 5 is a flowchart for explaining the operation, and FIG.
This figure is a flowchart for explaining the operation of another embodiment, and FIG. 7 is a flowchart for explaining the operation of an embodiment provided with an automatic correction function. 4-1, 4-2...Pump, 5-1. 5
-2... Motor for driving the pump, 8...
・Pressure sensor, pressure...inverter device, 21.
......breaker, ηA, 22B, MC...
itt magnetic contactor, field A, field B...magnetic contactor 2
2A. 22BK interlocking contacts, Sae, 25...Variable resistor, μcon...Microcomputer, CP
U...Central processing unit, iQl e...Memo IJ (ROM and RAM), F1 to F3...Interface, PIA-1 to PIA-5...
Input/output board, FBl, PBz...Push button switch, SWI, SW2...Deep inch, A...Power terminal, Z...Stabilized power supply. Figure 1 Figure 2rM Figure 3 Figure 4 Figure 5: @Figure 6! Figure 7

Claims (1)

[Claims] 1. In a liquid supply system comprising at least two pumps, the rotational speed and operation stop of the pumps are controlled according to the amount of liquid supplied, and the pressure of the liquid supplied is maintained within a predetermined range. , a means is provided for individually setting control conditions for each of the pumps, and control to stop the pumps when the liquid supply lid drops below a predetermined value is performed under independent control conditions for each pump. A liquid supply system control device characterized by being configured as follows. 2. In claim 1, the above? I11+
1. A liquid supply system control device, characterized in that the rotational speed is configured to be the minimum rotational speed of each pump. 3. The liquid supply system control device according to claim 1, wherein the control condition is configured to be a minimum pressure for stopping each pump.