JP2933249B2 - Water supply device and its pump control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates to a liquid supply device for water using the inverter, especially in the liquid supply device for suitable water for use directly connected to the water Dohon tube about the pump control method .

[0002]

2. Description of the Related Art Conventionally, a water supply pump for water supply is directly connected to a water main from the viewpoint of preventing water contamination due to backflow and preventing erroneous measurement of a water meter (water meter) due to a water hammer. it has been regulations. For this reason, as described in, for example, JP-A-59-188096, water is once injected from a water main into a water receiving tank, and the water in the water receiving tank is pumped up by a water supply pump and sent to each customer. That is the current situation.

Recently, while utilizing the pressure of the water main,
In order to eliminate unsanitary receiving tanks, studies have been started on a method of supplying water by directly connecting a water supply pump to a water main. It is considered that a water supply device using an inverter is effective for this in the following points.

1) If the pressure of the water main becomes high, the operating speed of the pump can be reduced in order to keep the pressure on the pump discharge side constant, and power is saved. 2) Since the pump can be started at a low speed when it is started, the pressure of the water main is not instantaneously reduced. 3) When the pressure of the water main decreases, the water supply to the customer can be adjusted by reducing the pump operation speed by the inverter.

[0005]

When the water supply pump is used directly connected to the water main, the above-mentioned advantages can be obtained. However, those who use a water supply system with a pump directly connected to the water main are residents of high-rise buildings of three or more floors, and ordinary consumers directly use the pressure of the water main without having a pump facility. Water is supplied from the water supply terminal.
For this reason, when a customer having a pump facility uses a large amount of water in the water main when the water main pressure is reduced due to a disaster or the like, a situation may occur in which water is not supplied to general consumers. Since such inequality is not preferable, it is necessary to provide a water supply device directly connected to a water main to be provided with a function capable of achieving horizontal water supply and the like. As a water supply device for direct connection to a main pipe for horizontal supply, for example, Japanese Patent Application Laid-Open No. 2-286
There is a technique described in 888 JP. In this prior art,
First to turn on / off the pump according to the pressure in the pressure tank
In addition to the control system, the second control system to adjust the pressure regulating valve provided on the outlet side pump according to the pressure of the water mains provided, when the main pressure is reduced, the second control system Depending on the function of
To prevent a large amount of water in the main pipe from being sucked into the pump.

According to the above-mentioned prior art, it is possible to achieve horizontal feeding when the main pipe pressure is reduced. However, in this conventional technique, since the first control system and the second control system both function in a coexistent manner, there is a problem that the pump performance is deteriorated and energy loss is increased. . Immediately
When the pressure in the water main decreases, the pressure in the pressure tank decreases due to a decrease in water supply to the pump, and the first control system turns on the pump.
By the control system, the outlet side of the pump is throttled by the pressure regulating valve,
In extreme cases, the pump is forced to shut off. In this, the pump performance is reduced pos- sibly risk is high breakage, also energy loss becomes large.

An object of the present invention, the water supply equally easily be realized, moreover, the liquid supply device for mains directly capable of saving energy without reducing the pump performance and to provide the pump control method It is in.

[0008]

SUMMARY OF THE INVENTION The object of the present invention is to provide a water supply system for direct connection to a water main which controls a pump operation speed so that a pressure detected by a pressure detecting means for detecting a water pressure becomes a target pressure. In addition to the discharge side pressure control mode, which controls the pump operation speed so that the detected pressure becomes the discharge side target pressure, the suction side pressure, which controls the pump operation speed so that the detected pressure on the pump suction side becomes the suction side target pressure A control mode is provided, and when the pump suction side detection pressure exceeds a predetermined pressure, the discharge side pressure control mode is selected.When the pump suction side detection pressure is lower than the predetermined pressure, the suction side pressure control mode is selected. It made reach by controlling the operating speed.

[0009] The above object was Hama, pumps for water supply fluid device for supplying the discharge side pressure detected by the water suction pump water main to control the operating speed of the pump to the control and demand side to the discharge side target pressure In the control method , when it is detected that the suction side pressure of the pump is lower than a predetermined pressure lower than the discharge side target pressure, the control of the discharge side detection pressure to the discharge side target pressure is stopped, and the pump is stopped. the operation speed is made reach to control deceleration.

[0010]

According to the present invention, two control modes, a discharge side pressure control mode and a suction side pressure control mode, are provided. According to the detected value of the suction side pressure, when the suction side pressure is high, the pump speed is controlled by the discharge side pressure control mode. If it can be determined that the suction side pressure is low and the supply level must be considered, the control mode is switched to control the pump speed in the suction side pressure control mode (in this case, the control)
I do. As a result, it is possible to achieve horizontal feeding and the like, and the pump is not forced to operate, so that its performance is not impaired and energy loss is reduced.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. Figure 1 is a liquid feed device for water according to a first embodiment of the present invention (hereinafter, will leave the water supply device) is a schematic diagram of a. Water supply apparatus of this embodiment comprises a suction pipe 2 connected to the water mains 1, a flow path (two in the illustrated example) a plurality of which are branched therefrom, the pump 10 provided in each flow path , 1
1, gate valves 8, 9 , 16 , 17 for partitioning the upstream and downstream sides of the pump for each flow path, respectively;
A water supply pipe 20 that combines each flow path on the downstream side of 6, 17
A first pressure sensor 18 for detecting the pressure on the discharge side of the pump (in this embodiment, the pressure in the water supply pipe 20); and a pressure tank 19 having an air reservoir therein and accumulating the water in the water supply pipe 20 . A second pressure sensor 7 provided in the suction pipe 2 for detecting a suction side pressure of the pump (in this embodiment, a pressure in the suction pipe 2), and a control device 21 for controlling the pumps 10 and 11
Is provided.

As will be described later in detail, the control device 21 stops the operation of the pump when the pressure of the water main 1 becomes higher than the discharge side target pressure for a certain period of time, and the pressure of the water main 1 is discharged. When the pressure drops below the side target pressure, it functions to restart the pump. As shown in FIG. 3 , the control device 21 includes inverters 26 and 27 for controlling the speeds of the pumps 10 and 11, and when the pressure of the water main 1 drops below a predetermined lower limit pressure, the target pressure Is set to this lower limit pressure, and whenever the suction side pressure detected by the second pressure sensor 7 becomes lower than the target pressure (lower limit pressure), the speed of the inverter is commanded to decrease, and when they are equal, the speed is maintained. When the target pressure (lower limit pressure) is exceeded, a speed increase command is issued, and the target pressure is replaced with a regular target value (a discharge side target pressure desired by the water supply system in advance). speed control, i.e., normal speed control performed (discharge side <br/> pressure Hayashi increase becomes lower than the discharge-side target pressure, the speed control for decelerating the higher).

The details will be described below. Figure 2 is a system diagram showing an example of the water supply to the customer directly connected to the water supply device to water mains, the suction pipe 2 -1 branched from water main 1,
In 2-2 and 2-3, water supply devices 3-1 and 3-2, respectively
3-3 is provided, and each water supply system is
To 1,5-2,5-3, the water supply pipes 4-1,4-2,4-3
Water is supplied via

[0014] Each of the water supply apparatus shown in FIG. 2 are the same configuration in the present embodiment, illustrating one configuration of which Figure 1. In these water supply devices, in addition to the above-described configuration, a check valve (prevention of backflow) 6 for preventing pollution is attached to the suction pipe 2 on the upstream side of the pressure sensor 7 , and a small amount of water is provided on the downstream side of the pump in each flow path. The flow switches 23 and 24 for detecting a use state are mounted, and the check valves 14 and 15 are mounted between the flow switches 23 and 24 and the gate valves 16 and 17 of each flow path. The pumps 10 and 11 are driven by electric motors 12 and 13 controlled by a control device 21.

FIG. 3 is a detailed block diagram of the control device 21. The control device according to the present embodiment supplies the electric power from the power supply PW to the electric motor 12 via the wiring breaker 51, the main circuit contacts 52a and 25a of the coils 52 and 25 of the electromagnetic contactor, and the inverters 26 and 27, respectively. , 13 and the motors 12, 1
3 is controlled. Various settings for each of the inverters 26 and 27 (for example, settings for the lower limit of the operating speed range of the inverters) are input from consoles (key input devices) 45 and 46.

N1 and N2, which will be described later, are signals for instructing the speeds of the inverters 26 and 27.
a is the same operation command signal input line, these input lines 28 a, ON switches X1, X2 provided on the 29a
At times, the electric motors 12 and 13 are operated. When the switch 30 is closed, the stabilized power supply unit 3 is closed.
1 operates, control power is supplied to the power supply terminal 33, and preparation for automatic operation is completed.

34 and 35 are inverters 26 and 35, respectively.
An interface constituted by a D / A converter or the like for issuing a speed command to 27, a CPU 36 as a microcomputer , a memory 37 consisting of a RAM and a ROM, and an input / output port 38, 39, 40, 41 It is. Reference numerals 42 and 43 are switches for setting pressure and speed data.

[0018] From the switch 42, the target pressure H0 details described in Figure 4 below, the pump starting pressure H3, (in terms of water 0) pressure H1 is the target value in the case of constant end pressure control shown in FIG. 5, H4 (point of the water amount Qa), a value such as a pressure i for switching from discharge-side control to suction-side control when the main pipe pressure falls below a specified value, and the switch 43 sets the operating speeds ND and NA. Set the data and enter
The data is read into the memory 37 via the ports 39 and 40 (stored in the RAM). Of course , the RO in this memory 37
In M, a program such as an operation control procedure described later is written. Note that ND is an initial value, and the main pipe pressure is set in advance based on the value of i.

The interface 44 is connected to the first sensor 18.
And the pressure signal detected by the second pressure sensor 7 is A /
The input port 41 is used for D conversion and reading.
Is stored in the RAM in the memory 37 via the.

FIG. 4 is an operating characteristic diagram in the case of a general discharge pressure constant control system. The vertical axis shows the total head H and the horizontal axis shows the water quantity Q. Curves A, B, C, and D show that the operating speed is continuous, but the speed is NA (maximum speed), N
Pump Q when assumed to be B, NC, ND (minimum speed)
-H performance, and H0 is the discharge target pressure at this time. FIG. 5 is an operation characteristic diagram in the case of a general terminal pressure constant control system. 4 are the same as those shown in FIG. In FIG. 5, a curve E is a resistance loss curve of a water supply pipe or the like. In these control methods, the amount of water used is
Q b, Q b, Q c, the changes Q D, of course, the operating speed of the inverter, NA, NB, NC, ND and varied, the operating point of the pump on the pressure constant linear H0 out come ejection, or terminal On the constant pressure line, the pressure changes as i, b, c, d.

Normally, a constant discharge pressure control method is often used for supplying water to an apartment or condominium where the pipe resistance is small relative to the actual head of the pump. In the case of a long water supply pipe having a large pipe resistance with respect to the actual head, a constant end pressure control method is used. Which method is to be adopted is selected as the optimum one for the water supply system, and the operation is controlled by an operation procedure programmed in advance in accordance with the above-described operation characteristic diagram.

FIG. 6 shows the effect of a change in the pressure of the water main 1 during operation according to these control methods.
This will be described below. In FIG. 6 , the vertical axis represents the pressure at the mounting portion of the first pressure sensor , that is , the discharge pressure (pump discharge side).

In FIG. 6 , the operating point C for the water quantity Q is shown in FIG.
4 , the pump Q of the operating speed NC is determined based on the value when the main pipe pressure is i (the lower limit of the fluctuation).
An H performance curve C is determined. If the main pipe pressure increases from i to j at this time, the pump moves to a pump QH performance curve C 'indicated by a broken line. Accordingly, the cutoff pressure naturally changes from HSC to HSC ' , and the operating point also changes from C to C' . At this time, since the example of the constant discharge pressure control method is shown as the control method, the operating speed is reduced by the pressure control.
And the pump QH performance curve changes from C 'to C,
The points are returned from Ha 'to Ha. Updated by this pressure control
Assuming that the operating speed to be performed is NC ', NC' is the discharge pressure
That the force changes in proportion to the square of the operating speed of the pump
Considering this, it is given by the following equation 1.

[0024]

(Equation 1)

However, when NC: main pipe pressure i, pump shutoff
Pump operating speed HSC required to generate pressure HSC: Pump operates at operating speed NC at main pipe pressure i
Clamping switching pressure HSC 'when being: when mains pressure j (≧ i), the pump operating speed
Is the deadline pressure of time that has been operating in the NC. Note that HS is provided between HSC ′, HSC, j and i.
There is a relationship of C ′ = HSC + (ji).

When the main pipe pressure is i and the amount of water used is Q
At (0), the operating speed is reduced, and eventually reaches the minimum speed ND. Further, consider a state in which the main pipe pressure has increased to j.

If the operating speed ND does not change, the pump QH curve D moves to a curve D 'shown by a broken line.
Therefore, when the amount of water used decreases, the pressure increases along the curve D ', and exceeds H0 to reach the maximum HSD'. In this case, the operating speed ND should not be limited but updated to a lower speed, or the operating speed should reach the minimum speed every time the operating speed reaches ND and the pressure detected by the pressure sensor exceeds H0. the ND, details as described in Figure 9 after, so as to update automatically calculated. Thus, even if the main pipe pressure fluctuates, the pressure on the discharge side can be kept constant in a predetermined relationship.
Note that the lower limit speed of the inverter can be preset from the consoles 45 and 46 as described above.

Next, the case where the main pipe pressure exceeds the planned value (pump discharge side target pressure value) will be described with reference to FIGS. In FIG. 7, the vertical axis indicates the discharge pressure, the main pipe pressure, and the inverter speed. Now, on the x point on the horizontal axis, the discharge pressure is 701 at H0, and the main pressure is 7 at i.
06, and the inverter speed is at ND 711.

In this state, the main pipe pressure rises and exceeds the planned value and becomes k (for example, j = H0, k> H).
0), the main pipe pressure moves to the point 708, the discharge pressure exceeds the point H0 and reaches the point 703, and the inverter speed reaches the NMIN set on the console to 713 points. In a state where the main pipe pressure is increased, a non-control state where the discharge side pressure of the pump cannot be controlled to the target pressure H0 cannot be achieved (above the y 'point on the horizontal axis). Therefore, in this embodiment, since the main pipe pressure can be maintained at H0 or more without operating the pump, the operation of the pump is stopped when the non-control state is established.

FIG. 8 is a flowchart showing the operation procedure of the pump. The procedure for stopping the operation of the pump will be described on this flowchart. First, step 80
At 0, the main pipe pressure is detected by the second pressure sensor 7, and it is determined whether or not the detected value exceeds the target pressure H0 (step 802). As a result of the determination, if it exceeds the H0 is on the main pressure detected by the pressure sensor 7 again after waiting a predetermined time t advances to step 803 (Step 8
04), a re-determination is made in step 805, and H
If it exceeds 0, the routine proceeds to step 806, where the operation of the pump is stopped. In this way, the pump stops when the main pressure continues to rise above the planned value for a certain period of time.
Is Runode, saving power, what power saving effect is obtained
It is . By the way, in the judgment in step 802,
When it is determined that the force is smaller than the target pressure H0,
Processing after step 807 is to be executed.
You. First, in step 807, steps 803 to 806
The pump is off or on
Has been determined, but in this determination it is determined to be OFF.
If so, the pump is started in step 808
It has become something. This is because water supply is not possible with mains pressure alone.
Water supply while the pump is running.
It is necessary to do it. After the pump is started,
Step 809 is executed.
If it is determined that the step is ON,
Step 809 is executed immediately without executing the step
Has become. In 809 steps, 800 steps
The main pipe pressure detected at the lower limit value i (discharge side control (or
Switch from suction side control) to suction side control (or discharge side control)
Pressure value for changing the pressure).
As a result of the comparison, i ≧ 7 (7 is the book detected by the sensor 7).
Indicates tube pressure. 814 steps
The subsequent processing is executed (described later). Ma
If i <7 as a result of the comparison (normal
H) means that the operation controls the pressure on the discharge side
From this, processing in 810 steps is performed
I have. In step 810, the output from the discharge-side pressure sensor 18
On the detected pressure value is compared with the target pressure HO, the comparison imaging
Processing according to the result is performed. Immediately
HO <18 (18 is the ejection side detected by the sensor 18)
Indicates pressure. The same applies to the following.)
Since it is higher than the above, the deceleration processing is performed in step 811.
If HO = 18, the discharge side pressure is equal to the target pressure.
No change in 812 steps because it matches HO
Speed processing (processing in which no speed change processing is performed) is further performed by the HO
If> 18, the discharge side pressure is insufficient, so that 8
After the speed increase process is executed in each of the 13 steps,
The process is returned to 800 steps.

Next, the pressure of the main pipe drops extremely, and the pressure in FIG.
Consider a case where the pressure i at 09 point drops to a pressure l (i> l) at 710 points ( z → z ′ on the horizontal axis). In such a state, water cannot be supplied to other consumers connected to the water main. Therefore, in order to protect the position such as feeding level, the control using the detection value of the pump discharge side pressure sensor 18 (discharge side pressure control mode) is changed from the pressure control using the detection value of the suction side pressure sensor 7 (the suction side pressure sensor). The control is switched to (control mode), and the speed control 810 in the normal state
The operation reverse to the steps 813 is performed.

That is, the value detected by the pressure sensor 7 in step 809 is equal to the lower limit value i set from the switch 42.
(See FIG. 7) It is determined whether it is lower. As a result of the judgment,
If it is not more than the lower limit value i , the process proceeds to step 814, and the target pressure HO is replaced with the lower limit value i. Then, in step 815, the detected pressure H from the pressure sensor 7 is compared with the target pressure i. As a result of the comparison , the detected pressure H is
If it matches the target pressure i, at step 817
After the non-shifting process has been performed, the process returns to step 800.
But the detected pressure H is smaller than the target pressure i.
818 steps to prevent abnormal decrease in mains pressure.
After deceleration processing is performed by the
Waiting for the time t to elapse, the processing returns to 800 steps.
It has been done.

Of course, during normal (normal) operation, the pressure sensor 7
Detection pressure from than exceeds the i, will perform the 8 10 after step process. But if not
Is a pressure control using the detection value of the suction side pressure sensor 7.
That is, the control is switched. More specifically
Is the pressure sensor 7 in step 815 as described above.
Is compared with the target pressure i.
If the judgment results are equal, go to step 817
The gear shift process is not performed and the main pipe pressure is lower than the lower limit value i.
If it has decreased, go to step 818 to decelerate.
Is what is being done. After the 818 step proceeds to 81 9 step, wherein, to operate the trip (protection circuit by the rapid deceleration of the inverter, pump drive
Waiting time that does not interrupt the power to the motor)
The t process is executed, the process returns to step 800, and the process is executed again from here.

Next, FIG. 4, in the control method of FIG. 5, the FIG. 9 embodiment for automatically setting the inverter minimum speed when the main pressure is varied in terms of water 0 (elevated) by the calculation explain.

At step 900 in FIG . 9 , initialization is performed. That is, when the main pipe pressure at the time of planning is the lower limit value i and the pump 1
100% operating speed (maximum speed NA) when the shut-off pressure (discharge pressure) as HS, several expression operating speed o'clock water 0 follows
2 or determined by the number Formula 3, keep this value as the initial value.

[0036]

(Equation 2)

[0037]

(Equation 3)

This initial value may be set in advance by the switch 43 shown in FIG. Number equation
(2) or (ji) shown in Expression 3 is the pressure fluctuation value of the main pipe known at the planning stage.

Next, in step 901, the pressure detected by the pressure sensor 7 is detected. In step 902, it is checked whether the pressure H (for example, k) detected by the sensor 7 exceeds the maximum value j of the initial value in 900 steps. If NO, the process jumps to step 905, and if it exceeds, the maximum value j is replaced with k in step 903. This means that the main pipe pressure rose beyond the planned value due to the influence of the water hammer. Then, 904 number equation 2 in step, or Equation 3 (j-i) to (k-i) Number Formula 4 is replaced with, or,
The minimum value of ND can be obtained by processing according to Expression 5.

[0040]

(Equation 4)

[0041]

(Equation 5)

The number Equation 2, Equation 3, Equation 4, the Equation 5, H0 FIG 4, H1 is the target pressure o'clock water 0 shown in FIG.

According to this, the main pipe pressure exceeds the planned value.
Even if it rises, the discharge side pressure matches the target pressure HO,
Since it easier to determine the appropriate value of the lowest frequency of the inverter, the pressure, as indicated by the curve D 'shown in FIG. 6 does not increase.

[0044] The second embodiment of the present invention FIGS. 10 and 1,
4, it will be described with reference to FIG.

[0045] This example, the pump starts with the configuration of FIG. 1, is taken into consideration so as not to affect the main pressure when stopping.

In this embodiment, 100, 1 in FIG.
In step 01, it is determined whether or not the pressure detected by the pressure sensor 18 (load side) has decreased to the starting pressure H3 or less (FIG.
4 , FIG. 5 ). As a result, if the pressure has dropped below the starting pressure, the first pump 10 is started at a minimum speed (not shown) determined by the initial value in step 102. Since the inverter is soft-start, it takes an acceleration time (several seconds) to reach this speed.

Next, the routine proceeds to step 103, where the main pipe side pressure is detected by the pressure sensor 7, and in step 104, the target pressure is replaced with the suction side lower limit pressure i. Then, in step 105, the pressure H detected by the pressure sensor 7 is compared with the target pressure H0 (= i).

As a result of the comparison, the detected pressure H is H0 (= i)
Equal, and kept at the minimum speed without shifting to (10
6 steps) . As a result of comparison, main pipe pressure (detected pressure H)
Is lower than H0 (= i: lower limit pressure),
As in steps 818 and 819 in FIG. 8, the deceleration process is performed (steps 107 and 108) . In this way, the main pipe pressure does not decrease due to the inertia of water at the time of starting. As a result of the comparison in step 105, if the main pipe pressure (detected pressure H) becomes higher than H0 (= lower limit value i), 1
Go to step 09 and set the target pressure to the suction side lower limit pressure i
From the target pressure HO on the discharge side. And 110
In a step, the discharge side pressure is detected by the pressure sensor 18.

Next, based on this pressure, in step 111, the same speed control as in the processing block X shown in FIG. 8 is performed. In steps 112 to 114, it is determined whether or not the flow rate sensor is ON with a small amount of water even after the lapse of the fixed time t1 . If it is not ON return to 10 5 step to continue the operation, at 115 to 118 step if the ON,
Search operation to stop without increasing the pressure too much (processing
Logical block Y) .

That is, in steps 115 and 116, a test operation is performed with the current speed reduced by, for example, about 10 Hz.
After elapse of Δt3 in step 116 , the discharge side pressure is detected in step 117, and this value becomes the target pressure in step 118.
Check if the force is equal to or higher than H0 (specified value). If the pressure be reduced rpm than the current as 10Hz is H0 more, it means that not using water demand end, at 120 steps, while targeted operating speed at 115 step
The preceding aircraft Ru is stopped in the state. By the way, the precedence here
The machine is one of a plurality of pumps and is powered on (shown in FIG. 3).
After turning on the circuit breaker 51 for wiring), first in 102 steps
The pump is started at Also, if 11
If the feed water pressure is lower than the target pressure H0 as a result of the determination in the eight steps, the operation speed is returned to the original in step 119, and the processing returns to step 110, and the subsequent processing is performed.

[0051] Further, After running 120 steps, the next 121 steps, then Unit pump operation (more
When a certain pump is the first unit, the second unit, ...
When the pump is called indefinitely, it simply replaces the "unit" with a dormant pump, returns to step 100, and executes the subsequent processing instructions. In this way, for example,
Increase the speed of the pump just before the stop to store water in the pressure tank.
Stop at a reduced operating speed compared to what was stopped.
Since the operation is stopped, a change in the amount of water at the time of stoppage is reduced, and the main pipe pressure does not increase due to the inertia of water at the time of stoppage, so that stable operation without pressure fluctuation can be realized.

As described above, in the present embodiment, the pump (water supply device) is directly connected to the water main, and the shortage of the main pressure is pumped by the pump to send water to the demand end, and the pressure sensor 18 supplies water. The pressure sensor is provided in the pipe 20 and generates a pressure signal in accordance with the pressure therein. The pressure sensor 7 is provided in the suction pipe 2 on the suction side of the pump, and also generates a pressure signal. A plurality of inverters, the pressure detected by the pressure sensor 7, 18, based on the relationship between the set value of the control system is set in advance (for example, a target value), the speed control and operation control, specific state pressure sensor
If it is detected from 7, it operates as follows
It has become.

A) When the pressure of the water main becomes larger than the preset target pressure on the discharge side, and the operation speed of the inverter reaches the minimum speed, and when this state has passed for a certain period of time, the pump is stopped. When the pipe pressure falls below the target pressure, the pump is operated again.

B) When the pressure of the water main reaches a preset lower limit pressure and the operation is switched from control by the pressure sensor on the discharge side to control by the pressure sensor on the suction side, the speed signal of the inverter is changed stepwise. Instead of commanding, make it gradually attenuate.

C) When the pump is started, the inverter outputs a low speed signal (step 102 in FIG. 10). If the pressure on the suction side is equal to the lower limit set value i, the inverter does not shift and maintains that speed (FIG. 10) . (Step 106 in FIG. 10 ) , and if the speed is lower, deceleration is performed (Step 107 in FIG. 10) .
At the time of a stop, before issuing a stop command, a search operation (processing block Y in FIG. 10) is performed to confirm whether a small amount of water is used, and if so, the inverter is operated so that the suction side pressure does not increase. Stop at a low speed.

D) Since the pressure fluctuation of the main pipe cannot be specified,
The lower limit value of the operating speed range of the inverter is set in advance to the minimum value, the pressure fluctuation of the main pipe is estimated and lowered in advance to match it, or the detection of the pressure sensor 7 provided on the suction side is performed. Based on the obtained pressure signal, it is automatically calculated and determined.

According to such an embodiment, the following effects can be obtained.
You. Water mains pressure exceeds pump discharge side target pressure
To stop and switch to water supply at mains pressure to save power.
Becomes

[0058]

According to the present invention, without reducing the pump performance feedwater equality when the pressure of the water main is lowered, only <br/> also, the energy can be performed without loss, A water supply device with high reliability and energy saving can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a liquid supply device according to an embodiment of the present invention.

FIG. 2 is a system diagram of a system in which a water supply device is directly connected to a water main.

FIG. 3 is a control circuit diagram of the embodiment of the present invention.

FIG. 4 is a QH characteristic diagram of discharge pressure constant control.

FIG. 5 is a QH characteristic diagram of terminal pressure constant control.

FIG. 6 is a QH characteristic diagram showing an influence when a main pipe pressure fluctuates.

FIG. 7 is an operation characteristic diagram showing a relationship among a discharge pressure, a main pipe pressure, an inverter speed, and a flow rate according to the embodiment of the present invention.

FIG. 8 is a flowchart showing an operation procedure of the first embodiment of the present invention.

FIG. 9 is a flowchart showing an operation procedure of the first embodiment of the present invention.

FIG. 10 is a flowchart showing an operation procedure of the second embodiment of the present invention.

[Explanation of symbols]

1: water main pipe, 2: suction pipe, 7, 18: pressure sensor, 1
0, 11: pump, 12, 13, electric motor, 19: pressure tank, 20: water supply pipe, 21: control device, 23, 24: flow sensor, 26, 27: inverter.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Kawa ▲ saki 7-1 1-1 Higashi Narashino, Narashino City, Chiba Prefecture Inside the Narashino Plant, Hitachi, Ltd. (72) Inventor Yoshisaburo Matsuno 7, Higashi Narashino, Narashino City, Chiba No. 1 in the Narashino Plant of Hitachi, Ltd. (56) References JP-A-2-286888 (JP, A) JP-A 55-136868 (JP, U) Public Showa 52-15123 (JP, B2)

Claims (14)

(57) [Claims] In a pump control method of a water supply device for direct connection to a water main, which controls a pump operation speed so that a pressure detected by a pressure detecting means for detecting a water pressure becomes a target pressure, a detected pressure on a pump discharge side is discharged. In addition to the discharge-side pressure control mode that controls the pump operation speed so as to reach the target pressure, a suction-side pressure control mode that controls the pump operation speed so that the detected pressure on the pump suction side reaches the suction-side target pressure is provided. When the pump suction side detection pressure exceeds a predetermined pressure, the discharge side pressure control mode is selected, and when the pump suction side detection pressure is lower than the predetermined pressure, the suction side pressure control mode is selected to control the pump operation speed. A pump control method for a water supply device for water supply. 2. The pump control method according to claim 1, wherein the suction side target pressure is set to the predetermined pressure. 3. A pump control method for a water supply system for supplying water to a demand side by controlling the operation speed of a pump to suck water in a water main and to control a discharge side detection pressure of the pump to a discharge side target pressure and to supply it to a demand side. When detecting that the suction side pressure of the pump is lower than a predetermined pressure lower than the discharge side target pressure, the control of the discharge side detection pressure to the discharge side target pressure is stopped, and the operating speed of the pump is reduced. A pump control method for a water supply device for water supply, characterized by controlling. 4. A pump control method for a water supply device for direct connection to a water main, wherein a pump operating speed is controlled so that a pressure detected by a pressure detecting means for detecting a water pressure becomes a target pressure. In addition to the discharge-side pressure control mode that controls the pump operation speed so as to reach the target pressure, a suction-side pressure control mode that controls the pump operation speed so that the detected pressure on the pump suction side reaches the suction-side target pressure is provided. , when the pump suction side detected pressure exceeds a predetermined pressure by controlling the pump operating speed to select the discharge-side pressure control mode,
For water pump suction pressure water main pressure is decreased from this state, characterized by controlling the operating speed of the pump by the predetermined pressure falls below Rutoki is the suction-side pressure control mode by switching the control mode A pump control method for a liquid supply device. 5. A pump control method for a water supply device for direct connection to a water main, which controls a pump operation speed so that a pressure detected by a pressure detecting means for detecting a water pressure becomes a target pressure. In addition to the discharge-side pressure control mode that controls the pump operation speed so as to reach the target pressure, a suction-side pressure control mode that controls the pump operation speed so that the detected pressure on the pump suction side reaches the suction-side target pressure is provided. , when the pump suction side detected pressure falls below a predetermined pressure by controlling the pump operating speed to select the suction side pressure control mode,
Rutoki pump suction pressure water main pressure is increased from this state exceeds the predetermined pressure feed for water, characterized in that to control the operating speed of the pump by the discharge-side pressure control mode by switching the control mode Liquid device pump control method. 6. The control according to claim 1, wherein the control to set the pressure on the discharge side of the pump to the target pressure on the discharge side is performed so that the terminal pressure on the demand side is constant. A pump control method for a water supply device for water supply, characterized in that: 7. The pump according to claim 1, wherein the control to set the pressure on the discharge side of the pump to the target pressure on the discharge side is performed such that the discharge pressure of the pump is constant. A pump control method for a water supply device for water supply, characterized in that: 8. The pump according to claim 1, wherein the operation of the pump is stopped when the flow rate of the supply water to the demand side is equal to or lower than a predetermined flow rate, and when the pressure on the discharge side of the pump becomes lower than the starting pressure. A pump control method for a water supply device, comprising starting a pump. 9. The method according to claim 8, wherein the pump is stopped after the pump speed is reduced, and the pump is started by a soft start. 10. A water supply device for direct connection to a water main, comprising a pump control means for controlling a pump operation speed so that a pressure detected by a pressure detection means for detecting a water pressure becomes a target pressure.
The pump control means includes : a discharge-side pressure control mode for controlling a pump operation speed so that a detected pressure on a pump discharge side becomes a discharge-side target pressure; and a pump for controlling a pump pressure so that a detected pressure on a pump suction side becomes a suction-side target pressure. and a suction side pressure control mode for controlling the operating speed, the suction when the pump suction pressure detected by selecting the discharge-side pressure control mode when the pump suction side detected pressure exceeds a predetermined pressure is below a predetermined pressure water for use in liquid feed and wherein the control mode switching means to select the side pressure control mode setting <br/> Ke. 11. A suction pipe connected to a water main and provided with a backflow preventing means, a plurality of branch pipes branched from the suction pipe, and a water supply pipe joined at the outlet side of each branch pipe and connected to the demand side. A gate valve provided on each of the inlet side and the outlet side of each branch pipe, and the suction pipe provided between the inlet side gate valve and the outlet side gate valve of each branch pipe for each branch pipe. A pump corresponding to the branch pipe that discharges the sucked water to the water supply pipe side, an inverter that controls an electric motor that drives each pump, a first pressure detection unit that detects a pressure in the water supply pipe, a second pressure detecting means for detecting a pressure, the pre-Symbol discharge pressure control mode according to claim 1, wherein based on the detected pressure of said first pressure detecting means when the detected pressure of the second pressure detecting means exceeds a predetermined pressure Operation pump discharge
The discharge pressure control mode is switched to the suction pressure control mode according to claim 1, wherein the output pressure control mode is controlled to perform constant output pressure control and the detected pressure of the second pressure detection means falls below the predetermined pressure. Control means for controlling the speed of the operation pump based on the detected pressure. 12. A suction pipe connected to a water main and provided with a backflow prevention means, a plurality of branch pipes branched from the suction pipe, and a water supply pipe joined at the outlet side of each branch pipe and connected to the demand side. A gate valve provided on each of the inlet side and the outlet side of each branch pipe, and the suction pipe provided between the inlet side gate valve and the outlet side gate valve of each branch pipe for each branch pipe. A pump corresponding to the branch pipe that discharges the sucked water to the water supply pipe side, an inverter that controls an electric motor that drives each pump, a first pressure detection unit that detects a pressure in the water supply pipe, a second pressure detecting means for detecting a pressure, the pre-Symbol discharge pressure control mode according to claim 1, wherein based on the detected pressure of said first pressure detecting means when the detected pressure of the second pressure detecting means exceeds a predetermined pressure Demand side constant pressure control of operation pump When the detected pressure of the second pressure detecting means is lower than the predetermined pressure, the discharge side pressure control mode is switched to the suction side pressure control mode according to claim 1, and based on the detected pressure of the second pressure detecting means. And a control means for controlling the speed of the operation pump. 13. The pump according to claim 11, wherein a flow rate detecting means for detecting a flow rate on the downstream side of the pump, and the operation of the pump during operation is stopped when the flow rate detecting means detects a predetermined flow rate or less. And a water supply device for water supply. 14. The water supply according to claim 11, further comprising: means for stopping the pump after reducing the pump speed, and means for starting the pump by soft start. For liquid supply device.