JP2923250B2 - 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 directly connected to the water main, the above-described advantages can be obtained, but the following problems must be solved. 1) When the pressure of the water main becomes higher than the target pressure on the discharge side of the pump, the pressure cannot be controlled. 2) General consumers who do not have a water supply pump receive water at the pressure of the water main, but when the pressure of the water main decreases, the customer who has the water supply pump preferentially uses the water main to use the water main. When the water is sucked and the water is supplied, the main pipe pressure is further reduced, and it becomes impossible to supply the water to the general consumer, which is unequal. Therefore, from the standpoint of horizontal water supply, etc., when the pressure of the water main falls below the required pressure, the water supply is throttled, and the control of the water supply pump is controlled from the control that makes the discharge side constant, and the pressure on the suction side. It is necessary to prevent the pressure of the water main from dropping. However, when switching the control method without taking anything like Kano measures, inverter operates the trip (protection circuit for rapid deceleration, electric to the pump driving electric motor
Power) .

[0006] 3) If a water supply method directly connected to the water main is adopted, when the water supply pipe is actually laid locally,
Influence on water main pressure due to surrounding terrain (undulation of pipes, etc.)
Water hammer is generated on the suction side of the pump due to generation of water flow or a hydraulic gradient in the piping. However, as a water supply device, it is necessary to prevent these effects from affecting the discharge side of the pump. Further, it is conceivable that the main pipe pressure decreases when the water supply pump is started due to the inertia of the water and increases when the water supply pump is stopped. 4) Get fried pressure fluctuations are identified water main, it is impossible to properly determine the operating speed of the inverter.

An object of the present invention is to provide a water supply apparatus for water supply and a pump control method for saving power by saving power, and can cope with an increase in pressure of the water main, and a sharp increase in the water main. Even if the pressure drops, the inverter can be prevented from tripping.
It is still another object of the present invention to provide a reliable water supply apparatus for a water supply and a pump control method thereof , which can prevent an increase in main pipe pressure due to inertia of water at the time of stoppage.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pump control method for a water supply system comprising a pump for sucking water from a water main and supplying the water to a demand side. When it is detected that the pressure has exceeded
It made reach by stopping the operation of can the pump.

[0009] The above object is also attained by setting the pressure on the suction side of the pump to a pressure necessary for supplying water to the customer side in normal times.
And usually defined as a value above the suction side pressure
Beyond the discharge side target pressure that is, and et the operating speed of the pump is the lowest speed set in advance, it is made reach by stopping the operation of the pump.

The object of the present invention is to reduce the operating speed of the pump when the amount of demand water is small to determine whether the pressure on the discharge side of the pump is equal to or higher than a target pressure, and to stop the operation of the pump when it is equal to or higher than the target pressure. It made reach it.

[0011] The above object also the pump when the suction side pressure of the pump is below lowered to a preset starting pressure started at a predetermined low speed, the suction-side pressure of the pump is set after this when not exceed the lower limit pressure is done reaches by decreasing the operating speed of the pump.

[0012] The above object is also achieved by a suction pipe connected to a water main pipe, a backflow preventing means provided in the middle of the suction pipe,
A pump for supplying water sucked through the suction pipe to a demand side, a first pressure detecting means for detecting a discharge side pressure of the pump, and a second pressure for detecting a pump suction side pressure downstream of the backflow prevention means. Detecting means, and when the second pressure detecting means detects a pressure equal to or higher than a set lower limit pressure, the detection pressure of the first pressure detecting means becomes the target pressure set to be equal to or higher than the set lower limit pressure. It made reach it and a speed control means for controlling the speed of the pump.

[0013]

[Function] The pump suction side pressure becomes higher than the discharge side target pressure.
Once the pump is stopped, a power saving effect is obtained.
You. Also, the pump suction side pressure exceeds the discharge side target pressure,
Moreover, when the pump reaches the predetermined minimum speed,
Stopped, water mains pressure fluctuations are kept small
Power saving effect. Low demand water
When the pump operation speed is reduced,
It is determined whether the output pressure is equal to or higher than the discharge target pressure.
If the pressure is higher than the pressure, the pump will be stopped.
Pressure fluctuations can be kept small . Also, the pump discharge side pressure
When the pressure drops below the starting pressure, the pump starts at low speed,
At this time, if the suction side pressure falls below the set lower
The operation speed of the mains can be reduced,
Movement can be kept small . In addition, the suction connected to the water main
If there is backflow prevention means in the middle of the
Water is prevented from flowing back to the water main.

[0014]

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 in detail later, 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

[0017] 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.

The inverters 34 and 35 respectively correspond to the inverters 26 and
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.

[0021] 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 operation 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 water supply in apartments, condominiums, and the like 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 by 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.

[0027]

(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 the supply level, the control is switched from the control using the detection value of the pump discharge side pressure sensor 18 to the pressure control using the detection value of the suction side pressure sensor 7, and the speed control 81 in the normal state is controlled.
An operation reverse to the steps 0 to 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.

Naturally, 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.

[0039]

(Equation 2)

[0040]

(Equation 3)

[0041] The initial value may be set by the switch 43 shown previously in FIG. 3, instead of calculating. 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 has exceeded 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.

[0043]

(Equation 4)

[0044]

(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.

[0047] The second embodiment of the present invention FIGS. 10 and 1,
4, it will be described with reference to FIG.

[0048] 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,
A search operation (processing block Y) for stopping without increasing the pressure too high is performed.

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.

[0054] 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, the shortage of the main pressure is pumped by the pump and sent to the demand end, and the pressure sensor 18 supplies the 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 a preset target pressure on the discharge side, and the operation speed of the inverter reaches the minimum speed, the pump is stopped when this state has passed for a certain period of time. When the pipe pressure falls below the target pressure, the pump is operated again.

B) When the pressure of the water main reaches a lower limit pressure set in advance 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 stepwise changed. 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) , and when the suction side pressure 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 in 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. 1) If the pressure of the water main exceeds the target pressure on the pump discharge side, stop the operation and switch to water supply at the main pressure to save power.

2) The pump suction side pressure is equal to the discharge side target pressure.
Over when the pump reaches the minimum speed
Pump stoppage, which minimizes pressure fluctuations in the water main.
Power saving effect. 3 ) When the pump is stopped by using a small amount of water and the pump pressure is at a specified value, even if the pump is operated at an extremely low speed,
In the above case, the pump is stopped, so that the pressure fluctuation in the water main is small. 4) Pump when the pump discharge side pressure falls below the starting pressure
Is started at a low speed.
When the power falls below the operating speed of the pump is reduced
Therefore, the pressure fluctuation of the water main is small. 5) Means for preventing backflow in the middle of the suction pipe connected to the water main
The backflow of water from the pump side to the water main side.
Is prevented.

[0062]

According to the present invention, according to the increase of the main pipe pressure,
Power saving effect and start / stop at low speed
Therefore, pressure fluctuations in the water main can be kept small,
For those with backflow prevention means, the pump side to the water main side
This has the effect of preventing the backflow of water to the water.

[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, 2 ... suction pipe, 7, 18 ... pressure sensor,
10, 11 pump, 12, 13 electric motor, 19 pressure tank, 20 water supply pipe, 21 control device, 23, 24 ...
Flow rate sensors, 26, 27 ... inverters.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kosaburo Matsuno 7-1-1 Higashi Narashino, Narashino City, Chiba Pref. Hitachi, Ltd. Narashino Plant (56) 58-180796 (JP, A) JP-B 52-15123 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) F04B 49/00 F04B 49/06 321 F04D 15/00 E03B 11/00 E03C 1/00

Claims (14)

(57) [Claims] 1. A pump control method for a water supply system comprising a pump for sucking water from a water main and supplying the water to a demand side, wherein it is detected that the pressure on the suction side of the pump is higher than the target pressure on the discharge side. A pump control method for a water supply device for water supply, wherein the operation of the pump is stopped when the operation is performed. 2. A pump control method for a water supply system comprising a pump for sucking water from a water main and supplying the water to a demand side, wherein the pressure on the suction side of the pump is normally set on the consumer side.
Pressure required to supply water to the
Normal, exceeding the discharge-side target pressure, which is defined as the suction-side pressure or more values, and et the operating speed of the pump is the lowest speed set in advance, water, characterized in that to stop the operation of the pump Control method of pump for liquid supply device. 3. A pump control method for a water supply system comprising a pump for sucking water from a water main and supplying the water to a demand side. A pump control method for a water supply system, comprising: determining whether a pressure is equal to or higher than a target pressure; and stopping the operation of the pump when the pressure is equal to or higher than the target pressure. 4. A pump control method for a water supply system comprising a pump for sucking water from a water main and supplying the water to a demand side, wherein the suction side pressure of the pump decreases to reach a predetermined starting pressure or less. The pump is started at a predetermined low speed, and thereafter, when the suction side pressure of the pump does not exceed the set lower limit pressure, the operating speed of the pump is reduced, and Pump control method. 5. A pump for sucking water from a water main and supplying it to a demand side, first pressure detecting means for detecting a discharge side pressure of the pump, and second pressure detecting means for detecting a suction side pressure of the pump. Speed control means for controlling the speed of the pump so that the pressure detected by the first pressure detection means is equal to the target pressure; and the pressure of the water main increases and the second pressure detection means is equal to or higher than the target pressure. And a stop control means for stopping the operation of the pump when the pressure is detected. 6. A pump for sucking water from a water main and supplying it to a demand side, first pressure detecting means for detecting a discharge side pressure of the pump, and second pressure detecting means for detecting a suction side pressure of the pump. When the detected pressure of said first pressure detecting means, passing
The pressure required to supply water to the customer
And is usually defined as a value above the suction side pressure.
That the speed control means and the pressure of the water main is increased the second to control the speed of the pump so that the target pressure
The pressure detected by the pressure detecting means has exceeded the target pressure , and the operating speed of the pump has reached a preset minimum speed.
And a stop control means for stopping the operation of the pump. 7. A pump that draws water from a water main and supplies the water to a demand side, flow rate detection means for detecting a flow rate of water supplied to the demand side, first pressure detection means for detecting a discharge side pressure of the pump, Second pressure detection means for detecting the suction side pressure of the pump, speed control means for controlling the speed of the pump so that the pressure detected by the first pressure detection means becomes a target pressure, and Means for reducing the operating speed of the pump to determine whether or not the pressure detected by the first pressure detecting means is equal to or higher than a target pressure, and stopping the operation of the pump when the pressure is equal to or higher than the target pressure. Liquid supply device. 8. A pump that draws water from a water main and supplies it to a demand side, first pressure detecting means for detecting a discharge side pressure of the pump, and second pressure detecting means for detecting a suction side pressure of the pump. Speed control means for controlling the speed of the pump so that the pressure detected by the first pressure detection means is equal to the target pressure; and the pressure detected by the first pressure detection means decreases when the stopped pump is started. Pump starting means for starting the pump at a predetermined low speed when the pressure reaches a predetermined starting pressure or less, and thereafter operating the pump when the suction side pressure of the pump does not exceed the set lower limit pressure. And a means for reducing the speed. 9. A suction pipe connected to a water main, a backflow prevention means provided in the middle of the suction pipe, a pump for supplying water sucked through the suction pipe to a demand side, and a discharge of the pump. First pressure detecting means for detecting the side pressure, second pressure detecting means for detecting a pump suction side pressure downstream of the backflow prevention means, and the second pressure detecting means detecting a pressure equal to or higher than a set lower limit pressure. And a speed control means for controlling the speed of the pump so that the detected pressure of the first pressure detecting means is equal to or higher than the set lower limit pressure. Liquid device. 10. 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 connected to the demand side by merging the outlet sides of the respective branch pipes. 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 sucked water to the water supply pipe side, an inverter that controls a motor corresponding to the pump that drives each pump, and a first pressure detection unit that detects a pressure in the water supply pipe. A second pressure detecting means for detecting a downstream pressure of the backflow preventing means in the suction pipe;
A water supply device for water supply, comprising: speed control means for performing the inverter speed control so as to control the speed of each of the pumps so that the pressure detected by the pressure detection means becomes a target pressure. 11. 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 connected to a demand side by merging the outlet sides of the respective branch pipes. 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 sucked water to the water supply pipe side, an inverter that controls a motor corresponding to the pump that drives each pump, and a first pressure detection unit that detects a pressure in the water supply pipe. A second pressure detecting means for detecting a pressure on the downstream side of the backflow preventing means in the suction pipe; and operating the plurality of pumps while exchanging the idle pump and the operating pump, and detecting the pressure of the second pressure detecting means. Above the specified pressure The discharge pressure of the operation pump is controlled to be constant based on the pressure detected by the first pressure detection means. When the pressure detected by the second pressure detection means falls below the predetermined pressure, the pressure detected by the second pressure detection means becomes the predetermined pressure. Control means for controlling the speed of the inverter so as to control the operation pump so as to satisfy the following condition. 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 sucked water to the water supply pipe side, an inverter that controls a motor corresponding to the pump that drives each pump, and a first pressure detection unit that detects a pressure in the water supply pipe. A second pressure detecting means for detecting a pressure on the downstream side of the backflow preventing means in the suction pipe; and operating the plurality of pumps while exchanging the idle pump and the operating pump, and detecting the pressure of the second pressure detecting means. Above the specified pressure When the speed of the inverter is controlled to control the operation pump so that the demand-side terminal pressure is constant based on the pressure detected by the first pressure detection means, and when the pressure detected by the second pressure detection means falls below the predetermined pressure. And a control means for controlling the speed of the inverter so as to control the operation pump so that the pressure detected by the second pressure detection means becomes the predetermined pressure. 13. 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 sucked water to the water supply pipe side, a flow rate detection unit disposed downstream of the pump of each branch pipe, and an inverter that controls a motor corresponding to the pump that drives each pump. First pressure detecting means for detecting pressure in the water supply pipe; second pressure detecting means for detecting pressure downstream of the backflow prevention means in the suction pipe; Drive the pump and (2) When the detected pressure of the pressure detecting means is equal to or higher than a predetermined pressure, the discharge pressure of the operation pump is controlled to be constant based on the detected pressure of the first pressure detecting means, and the detected pressure of the second pressure detecting means falls below the predetermined pressure. At this time, the speed of the inverter is controlled so as to control the operation pump so that the detection pressure of the second pressure detection means becomes the predetermined pressure, and the flow rate detection means disposed downstream of the operation pump detects a predetermined flow rate or less. Control means for stopping the operation pump when it is detected. 14. 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 sucked water to the water supply pipe side, a flow rate detection unit disposed downstream of the pump of each branch pipe, and an inverter that controls a motor corresponding to the pump that drives each pump. First pressure detecting means for detecting pressure in the water supply pipe; second pressure detecting means for detecting pressure downstream of the backflow prevention means in the suction pipe; Drive the pump and (2) When the pressure detected by the pressure detecting means is equal to or higher than a predetermined pressure, the inverter performs speed control to control the operation pump based on the pressure detected by the first pressure detecting means so that the terminal pressure on the demand side is constant. When the detected pressure of the second pressure detecting means is lower than the predetermined pressure, the speed of the inverter is controlled so as to control the operating pump so that the detected pressure of the second pressure detecting means becomes the predetermined pressure. And a control means for stopping the operation pump when the flow rate detection means disposed on the side detects a flow rate equal to or lower than a predetermined flow rate.