JPH10176675A - Feed water system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress start/stop of an electric pump, and reduce noise by arranging a bypass pipe for connecting a delivery side and a suction side of the electric pump to each other, and switching control of the electric pump from an estimated terminal pressure constantly controlling unit into a pumping head control part in the case where a signal having a minimum flow rate and less is detected continuously for a prescribed time by a flow rate detecting means. SOLUTION: A feed water piping 1 comprises a feed water main pipe 2 and feed water branch pipes 3A, 3B, and electric pump 12 (12A, 12B) is arranged on each feed water branch pipe 3A, 3B. Bypass pipes 15A, 15B are arranged to connect a delivery side and a suction side of the electric pump 12 to each other, and electric valves 16A, 16B are interposed between them. Pressure detectors 18, 20 and a flow switch 19 are arranged on the feed water main pipe 2, and the electric pump 12 is controlled through inverters 22A, 22B on the basis of the output thereof. Namely, in the control unit 21, in the case where a minimum flow rate and less is detected, control of the electric pump 12 is switched from an estimated terminal pressure constantly controlling unit into a shut-off pumping head control unit for controlling the electric pump 12 serving the pumping head having a set pumping head or more as a first pumping head.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water supply device for supplying water with an electric pump.

[0002]

2. Description of the Related Art In the above-described conventional water supply apparatus, a flow switch, a check valve, and the like are provided in a water supply pipe downstream of an electric pump, and an electric pump is controlled by an estimated terminal pressure constant control section or a discharge pressure constant control section. It is configured to control via an inverter.

In this water supply apparatus, when the faucet disposed at the end side of the water supply pipe is opened to release water, each control unit detects a flow of water from a flow switch or the like, that is, a flow detection signal. Based on the above, the electric pump is rotated so that the estimated terminal pressure is constant or the discharge pressure is constant, and water is pressurized and supplied. Then, when the faucet is closed, the flow switch or the like outputs a flow rate non-detection signal which is a first signal in which the flow of water is no longer detected.
The electric pump is stopped based on a flow rate non-detection signal from a flow switch or the like.

Since the water pressure in the water supply pipe decreases after the faucet is opened until the operation of the electric pump, water of a predetermined pressure is discharged from the pressure tank to the water supply pipe by providing a pressure tank. Then, a predetermined amount of water at a predetermined pressure is stored in the pressure tank from when the faucet is closed until the electric pump stops. Therefore, it is possible to supply water with a stable water pressure, and to reduce the start and stop of the electric pump.

[0005]

In the conventional water supply device, the electric pump is started and stopped based on the opening and closing of the faucet. Therefore, the frequent start and stop of the electric pump causes a large noise generated when the electric pump is operated. Is a problem. In addition, the frequent start and stop of the electric pump shortens the life of the mechanical seal and the bearing of the electric pump, so that the maintenance cost of the electric pump increases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned inconvenience, and it is an object of the present invention to provide a water supply device which has low noise and can reduce maintenance costs.

[0007]

According to a first aspect of the present invention, a check valve is provided in a water supply pipe downstream of an electric pump, and the electric pump is controlled by an estimated constant end pressure control section via an inverter. In the water supply device, the discharge side of the electric pump located upstream of the check valve is connected to the suction side of the electric pump, and the flow rate downstream of the check valve is less than or equal to the minimum flow rate. When the first signal is output, and when the flow rate is greater than the minimum flow rate, the flow rate detection means outputs a second signal;
When the first cutoff head control unit that controls the electric pump via the inverter with the lift larger than the set maximum cutoff head as the first head and the flow rate detection means continuously outputs the first signal for the first predetermined time, the electric pump is turned on. A switching control unit for switching the control of the pump from the constant estimated end pressure control unit to the first dead-end head control unit.

An electric pump is connected to the inverter via an inverter by setting the first head to be equal to or less than the allowable maximum cutoff head and equal to or more than the set maximum cutoff head, and setting the second head to be equal to or less than the set maximum cutoff head and equal to or larger than the set minimum cutoff head. A second deadline head control unit for controlling the electric pump is provided. When the flow control unit outputs the first signal for a second predetermined time after the first predetermined time, the control of the electric pump is controlled by the first deadline head control. It is desirable to adopt a configuration in which the section is switched to the second deadline head control section.

Further, the electric pump may be configured such that the first head is a set maximum cutoff head, the first lift is a set maximum cutoff head, and the second head is a head smaller than the set maximum cutoff head and not less than the set minimum cutoff head. A second deadline head control unit controlled via an inverter is provided, and the switching control unit controls the electric pump when the flow rate detection unit outputs the first signal for a second predetermined time after the first predetermined time. It is desirable to switch from the first deadline head control unit to the second deadline head control unit.

Further, the first head is smaller than the set maximum cutoff head and is larger than the set minimum cutoff head,
The electric pump is set as the set minimum deadline head as the second head,
A second deadline head control unit controlled via an inverter is provided, and the switching control unit controls the electric pump when the flow rate detection unit outputs the first signal for a second predetermined time after the first predetermined time. It is desirable to switch from the first deadline head control unit to the second deadline head control unit.

The throttle valve alone or the throttle valve and the motor-operated valve are provided in the bypass pipe, and the motor-operated valve is controlled only by the estimated end pressure constant control unit or the discharge pressure constant control unit when the electric pump is controlled via the inverter. It may be configured to be closed by the switching control unit.

Next, a second invention provides a water supply device in which a check valve is provided in a water supply pipe downstream of an electric pump, and water is supplied by controlling the electric pump via an inverter by a constant discharge pressure control section. In, the discharge side of the electric pump located upstream of the check valve, the bypass pipe connecting the suction side of the electric pump, and the flow rate downstream of the check valve,
A flow rate detection means for outputting a first signal when the flow rate is equal to or less than the minimum flow rate and outputting a second signal when the flow rate is higher than the minimum flow rate; A first cutoff head control unit that controls the electric pump as a head via an inverter, and when the flow rate detection unit continuously outputs the first signal for a first predetermined time, the control of the electric pump is performed from the constant estimated end pressure control unit. First
And a switching control unit for switching to the deadline head control unit.

[0013] The first pump is set to be equal to or less than the allowable maximum cutoff head, equal to or more than the set maximum cutoff head, and is set to be equal to or less than the set maximum cutoff head and equal to or larger than the set minimum cutoff head. A second deadline head control unit for controlling the electric pump is provided. When the flow control unit outputs the first signal for a second predetermined time after the first predetermined time, the control of the electric pump is controlled by the first deadline head control. It is desirable to adopt a configuration in which the section is switched to the second deadline head control section.

Further, the first pump may be set to a set maximum cutoff head, or the first lift may be set to a set maximum cutoff head, and a second head is set to be smaller than the set maximum cutoff head and equal to or larger than the set minimum cutoff head. A second deadline head control unit controlled via an inverter is provided, and the switching control unit controls the electric pump when the flow rate detection unit outputs the first signal for a second predetermined time after the first predetermined time. It is desirable to switch from the first deadline head control unit to the second deadline head control unit.

In addition, the first head is smaller than the set maximum cutoff head and larger than the set minimum cutoff head,
The electric pump is set as the set minimum deadline head as the second head,
A second deadline head control unit controlled via an inverter is provided, and the switching control unit controls the electric pump when the flow rate detection unit outputs the first signal for a second predetermined time after the first predetermined time. It is desirable to switch from the first deadline head control unit to the second deadline head control unit.

The throttle valve alone or the throttle valve and the motor-operated valve are provided in the bypass pipe, and the motor-operated valve is controlled by the estimated end pressure constant control unit or the discharge pressure constant control unit only when the electric pump is controlled via the inverter. It may be configured to be closed by the switching control unit. Note that one end of the bypass pipe connected to the suction side of the electric pump may be connected to the water receiving tank.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a water supply device according to one embodiment of the present invention. The signal lines from the control unit to each motor-operated valve are not shown. In FIG. 1, reference numeral 1 denotes a water supply pipe, one end of which is connected to a water pipe (not shown), and a plurality of taps (not shown) are provided at the other end. The water supply pipe 1 is provided with a water supply main pipe 2
And two water supply branch pipes 3A and 3B inserted in parallel in the middle of the water supply main pipe 2.

Reference numeral 11 denotes a check valve disposed on the water supply main pipe 2 upstream of the water supply branch pipes 3A and 3B, 12A and 12B denote electric pumps having a built-in electric motor, and the electric pump 12A is connected to the water supply branch pipe 3A. The electric pump 12B is provided in the water supply branch pipe 3B. 13A is an electric pump 12A
Check valve disposed on the water supply branch pipe 3A downstream of
3B is a check valve disposed on the water supply branch pipe 3B downstream of the electric pump 12B, 14A is a shutoff valve disposed on the water supply branch pipe 3A downstream of the check valve 13A, and 14B is a check valve 13B. 4 shows a shutoff valve provided in a water supply branch pipe 3B downstream of the water supply branch pipe 3B.

Reference numeral 15A denotes a bypass pipe, and the electric pump 1
A water supply branch pipe 3A downstream of the check valve 13A and downstream of 2A is connected to a water supply branch pipe 3A upstream of the electric pump 12A. A bypass pipe 15B connects the water supply branch pipe 3B downstream of the electric pump 12B and upstream of the check valve 13B to the water supply branch pipe 3B upstream of the electric pump 12B.

Reference numeral 16A denotes a motor-operated valve provided in the bypass pipe 15A, which is controlled by a switching control unit 21t described later and opens and closes the flow path of the bypass pipe 15A. 1
Reference numeral 6B denotes a motor-operated valve disposed in the bypass pipe 15B, which is controlled by the switching control unit 21t to open and close the flow path of the bypass pipe 15B. 17A is the bypass pipe 15A
The throttle valve 17B indicates a throttle valve provided in the bypass pipe 15B.

Reference numeral 18 denotes a pressure detector disposed in the feed water main pipe 2 upstream of the check valve 11, and 19 denotes a feed water branch pipe 3A, 3
A flow switch as flow rate detection means provided in the water supply main pipe 2 downstream of B, and 20 is a check valve 13A, 13B
2 shows a pressure detector disposed in the water supply main pipe 2 downstream of the pressure detector. Reference numeral 21 denotes a control unit that controls the electric pumps 12A and 12B via inverters 22A and 22B based on the outputs of the pressure detectors 18 and 20, and controls the electric valves 16A and
16B.

FIG. 2 is a block diagram showing the configuration of the control unit shown in FIG. Note that signal lines from the switching control unit to each motor-operated valve and each selection switch are not shown.
In FIG. 2, 21a indicates the presumed terminal pressure setter, a fixed lift h _c plus pipe end pressure h _k to actual head h _a, the presumed terminal plus a pipe loss lift kq ² to the fixed lift h _c and outputs the pressure h _s.

[0023] 21b shows a subtracter, the presumed terminal pressure setter 21a outputs the presumed terminal pressure h _s from the pressure detector 2
0 and outputs a minus pressure h _i detected. Reference numeral 21c denotes a selection switch for selecting the output of the subtractor 21b or the output of a subtractor 211 described later. Reference numeral 21d denotes a proportional-integral controller, which outputs the output of the subtractor 21b via the selection switch 21c or the subtractor 2
1l is processed and output to inverters 22A and 22B and a straight line commander 21e to be described later.

Reference numeral 21e denotes a linear command device, and the inverter 2
It has the same characteristics as the linear command device built in 2A, 22B, and receives the output of the proportional-integral controller 21d. 21f indicates a first-order lag element, and the electric pump 12A,
The output of the linear instructor 21e is output as n ^* by approximating the transmission delay of the motor to its speed (rotation speed or frequency) in 12B. Reference numeral 21g denotes a squaring operation unit, which receives the output n ^* of the primary delay element 21f and outputs n ^{* 2} .

Reference numeral 21h denotes a constant multiplier.
1g of the output n ^{* 2} to the electric pump 12A, the an, ^{* 2} multiplied by constant a is a characteristic of 12B is output as h _poi. 21i the first shut-off lift setter for outputting a set maximum deadline lift h _Pomax as a first lift, 21j and the second shut-off lift setter for outputting a set minimum deadline lift h _po of the second lift, 21k selection switch The selection switch 21k is connected to the output of the first deadline head setting device 21i or the second deadline head setting device 21j.
Is selected.

[0026] 21l represents a subtractor, the output h _poi of the first shut-off lift setting device 21i of the set up deadline lift h _Pomax or second shut-off lift setter 21j set minimum deadline lift h _po constant multiplier from 21h, It outputs the deducted one. 21m indicates a constant setting device,
The compensation head _homin is set. 21n shows the adders, and outputs the fixed lift h _c of the presumed terminal pressure setter 21a outputs, a material obtained by adding the compensation lift h _Omin output from the constant setting unit 21m.

Reference numeral 21o denotes a constant setting device, which is a check valve 11
The fixed loss head h _suc is set. 21p denotes a subtractor, which outputs a value obtained by subtracting the fixed loss head h _suc of the constant setting device 21o from the pressure h _su detected by the pressure detector 18. 21q represents a subtracter, and outputs the minus output of the subtractor 21p from the output of the adder 21n as h _pos.

Reference numeral 21r denotes a subtracter, which outputs a value obtained by subtracting the output of the constant multiplier 21h from the output of the subtractor 21q. 21s denotes a comparator, and a subtractor 21r
Is determined to be zero or more or negative, that is, whether the output of the flow switch 19 is equal to or less than the minimum flow rate q _{min that} can be detected. Reference numeral 21t denotes a switching control unit, and based on the output of the comparator 21s, the electric valve 16A, 1
6B and the selection switches 21c and 21k are controlled as described later, and are constituted by a ROM, a RAM, a CPU, a timer, and the like.

The constant estimated end pressure control section comprises an estimated end pressure setting unit 21a, a subtractor 21b, and a proportional integral controller 21d. The first deadline head control unit includes a proportional-integral controller 21d, a linear commander 21e, a first-order lag element 21f, a square calculator 21g, and a constant multiplier 21.
h, first deadline head setting device 21i and subtractor 21l
It is composed of

Further, the second deadline head control section includes a proportional-integral controller 21d, a linear commander 21e, a first-order lag element 2
1f, a square operation unit 21g, a constant multiplier 21h, a second deadline head setting unit 21j, and a subtractor 211. In addition, the flow rate detecting means includes an estimated terminal pressure
a, subtracter 21b, proportional-integral controller 21d, linear commander 21e, first-order lag element 21f, square operator 21g, constant multiplier 21h, constant setting units 21m, 21o, adder 21
n, subtracters 21p, 21q, 21r and comparator 21s
It is composed of

FIG. 3 is a head-flow rate characteristic diagram for explaining the operation of the water supply device shown in FIGS. This property is
If the effective push-in head is zero, that is, from the suction-side push-up head (pressure h _su in FIG. 2), the check valve 11
FIG. 7 is a graph showing, in unit method, a head-flow rate characteristic of the electric pump of the constant control of the estimated end pressure when the value obtained by subtracting the fixed loss head h _suc is zero.

In FIG. 3, A is an estimated terminal pressure constant control curve, R is a loss curve obtained by adding the friction loss of the bypass pipe 15A or the bypass pipe 15B and the throttle loss of the throttle valve 17A or the throttle valve 17B, and P ₁ is the estimated curve. Terminal pressure constant control curve A
Q = 1.0 in the above, the rated flow rate through the h = 1.0, the operating point of the rated pump head, P ₂ is the operating point at the minimum flow rate q _min putative terminal pressure constant control curve A, P ₃ the first shut-off the operating point of the pump head control, P ₄ is the operating point in the second shut-off lift control, first by opening P ₅ is an electric valve 16A, the 16B 1
Bypass pipes 15A, 15 when deadline head control is performed
Shows the operating point of the bypass flow rate q _B flowing to the B. The operating points P _{3 to} P ₅ are located on the loss curve R.

Here, each control will be described. First, when the estimated end pressure constant control is performed, the estimated end pressure constant control curve A
While moving between the operating point of the upper P ₁ and the operating point P ₂ Noto will water.

Then, when the first deadline head control is performed,
Operating point, the operating point P _3. The setting up deadline lift h _Pomax is acceptable, smaller than the minimum lift of the presumed terminal pressure constant control, also slightly smaller than the fixed lift h _c, when the flow rate of the bypass pipe 15A or the bypass pipe 15B is in bypass flow q _B (The check valves 13A and 13B are closed and the bypass pipe 15
Electric pump 1 in the state of reflux through A, 15B
(Head to keep the temperature rise of 2A and 12B below the allowable value) h
_It is smaller than _pmax and approximates the maximum allowable deadline head _hpmax . Shaft power in this operating point P ₃ is the relationship between the operating point pressure _{h PB} ≒ h pomax, it can be expressed as equation (1).

[0035]

(Equation 1)

Here, l ₂ : shaft power at operating point P ₃ (p.
u. _{) = L 2 / L N (} p.u.) L 2: the operating point P ₃ of the shaft power (kW) L _N: Teikakujiku power _(kW) h pomax:. Set up deadline lift (p.u) <( h <sub>a
+ H k) (p.u) h</sub> a:.. Actual head _{(p.u) = H a / H} N (p.u.) h k:. Tube end pressure _{(p.u) = H K / H} N (Pu) H _a : actual head (m) H _k : pipe end pressure (m) H _N : rated head (m) of electric pumps 12A and 12B η _qB : bypass flow rate q _B (pu) electric pump efficiency (p.u.) q _B when the: bypass flow rate in the first shut-off lift control (p.u.)

From the shaft power given by the equation (1),
Bypass pipe lift loss, the shaft power obtained by subtracting the work amount given to water, the electric pump 12A, it means that consumed in the 12B, when the bypass flow rate q _B is too small, the electric pump 12A, the water in the 12B , The temperature of the impeller, the packing, the bearing, the mechanical seal, the electric motor coil and the like will increase. Then, the relationship between the shaft power and the bypass flow rate is determined by an experimental value or a test value so that the temperature rise of each part falls within the specified value for each electric pump, and the relationship between the determined shaft power and the bypass flow rate is satisfied. determine the maximum allowable deadline lift h _pmax, determines the set maximum deadline lift h _Pomax.

The operating point P ₃ at the operating point or set maximum deadline lift h _Pomax, in this way the maximum allowed deadline lift h _pmax obtained are check valves 13A, 13
This is the operating point at which B remains closed. Then, the set maximum _cutoff head h _pomax can be operated continuously while the electric pumps 12A and 12B can be continuously operated while the temperature rise is not more than an allowable value.
The electric pumps 12A and 12B can be operated by setting the temperature rise to an allowable value or less for a limited time for the allowable maximum cutoff height _hpmax .

When the second deadline head control is performed, the set minimum deadline head becomes h _po . This set minimum cutoff head _hpo is a value that satisfies the expression (2), and is a value as close as possible to the allowable minimum cutoff head _hpmin that can lubricate the mechanical seals of the electric pumps 12A and 12B and minimize the frictional resistance. Set to.

[0040]

(Equation 2)

[0041] However, h _pmax: the maximum allowed deadline lift _{<(h a + h k)} h po (p.u.) (P.u.): Minimum deadline lift set (p.u.) h _pmin: allowable minimum deadline Head (pu) In the second dead-end head control given by the equation (2), the electric pumps 12A and 12B are operated at a low speed, resulting in a quiet and energy-saving operation. Although the set minimum cutoff head h _po allows the electric pumps 12A and 12B to be continuously operated, the allowable minimum cutoff head _hpmin can operate the electric pumps 12A and 12B for a limited time.

Further, detection of a small flow rate by the flow rate detection means will be described. In FIG. 3, the small flow rate operation is (h-q)
Assuming that _min , the cutoff head provided by the electric pumps 12A and 12B at this time has the hq characteristic of the electric pumps 12A and 12B.
When approximated by a quadratic expression of the speed and the flow rate of 12B, it can be expressed as Expression (3).

[0043]

(Equation 3)

Where: a: constant of electric pumps 12A, 12B n: speed (pu) of electric pumps 12A, 12B = N
/ _{N N} (p.u.) _N: the electric pump 12A, the speed of the 12B (rpm) _N N: the electric pump 12A, the rated speed of the 12B (rpm) h _a: actual head (p.u.) h _k: tube end pressure _(p.u.) h omin: compensating lift _{(p.u.) h su: (.} p.u) pump pushing lift = H _su / H _N
(Pu) H _su : Pump push-in head (entrance side of check valve 11)
( _M ) H _N : Rated head of electric pump 12A, 12B (m) h _suc : Fixed loss head of check valve 11 (pu) = H
_{suc / H N (p.u.) H} suc: fixed loss lift of the check valve 11 (p.u.)

(H _su -h _suc ) in the equation (3) is the effective push-in head, and as shown in FIG. 1, when the pressure detector 18 is provided on the water pipe side, the detected value is It is obtained by the difference between the pressure h _su and the actually measured fixed loss head h _suc . Therefore, the check valves 13A, 13B
It is possible to detect that the flow rate of the water supply main pipe 2 further downstream than the minimum flow rate q _min has been reached.

FIG. 4 is a flow chart of the switching control section in the water supply device shown in FIGS. In FIG. 4, ST1 to ST10 indicate steps.

Next, control of the switching control unit and water supply will be described. In a state where a faucet (not shown) is opened and water is supplied, the comparator 21s determines that the flow rate is the minimum flow rate q _min
More second signals are output. First, the switching control unit 21t is, the output of the comparator 21s it is determined whether the minimum flow rate q _min following the first signal (step ST1), the output of the comparator 21s is at the minimum flow rate q _min following the first signal if, that is, if the water supply state flow rate is the second signal is greater than the minimum flow rate q _min, selection switches 21c, 21k
To the contact a side, and the electric valves 16A, 16A
B is closed (step ST2), and the process returns to step ST1.

[0048] Thus selection switch 21c, the 21k is contact a control of the switching control unit 21t, the detected value of pressure h _i of the pressure detector 20, the presumed terminal pressure h _s of the estimated terminal pressure setter 21a The output of the proportional-plus-integral controller 21d changes to a set value and the difference between the two becomes zero,
It becomes a known estimated terminal pressure constant control. Therefore, the operating point P ₁ on the estimated terminal pressure constant control curve A in FIG.
Estimated end pressure constant control that moves between the _two .

When all the faucets are closed to reduce the flow rate to the minimum flow rate q _min or less, the comparator 21s
Outputs a first signal whose flow rate is equal to or less than the minimum flow rate q _min . When the first signal is output from the comparator 21s in this way, the switching control unit 21t confirms that the signal from the comparator 21s is the first signal (step ST1), and then sets a timer (step ST1). ST3). Then, it is determined whether a first predetermined time, for example, 60 seconds, has elapsed with reference to the timer (step ST4). If not, it is determined whether the first signal from the comparator 21s is continued. (Step ST5).

In the determination in step ST5, the comparator 21
If the first signal from s has not been continued, step ST
Returning to 1, if the first signal from the comparator 21s continues, the process returns to step ST4. If 60 seconds have elapsed in the determination of step ST4, the selector switch 21c is switched to the contact b side to open the electric valves 16A and 16B and set a timer (step ST6).

As described above, when the selection switch 21c is set to the contact b side under the control of the switching control section 21t, the output of the proportional-integral controller 21d is detected and the first dead-off head setting device 2
1i is the first _cutoff head control in which the output of the proportional-integral controller 21d changes so that the set maximum _cutoff head h _pomax is set to a set value and the difference between the two is set to zero, so that the _check valves 13A and 13B are slowly operated. While maintaining the pressure of the downstream water supply pipe 1, the water supply branch pipes 3A and 3B are closed, and the electric pump 1
The water discharged from 2A, 12B is supplied to the bypass pipe 15A,
It recirculates upstream of the electric pumps 12A, 12B via 15B.

Then, the switching control unit 21 t
It is determined whether the first signal from s is continued (step ST7). If the first signal from comparator 21s is not continued, the process returns to step ST2, and the first signal from comparator 21s is continued. If so, it is determined whether a second predetermined time, for example, 30 minutes, has elapsed with reference to the timer (step S
T8).

If it is determined in step ST8 that 30 minutes have not elapsed, the process returns to step ST7. If 30 minutes have elapsed, the selector switch 21k is switched to the contact b (step ST9), and the comparator 21s Waits for the signal from to become the second signal (step ST10). As described above, the selection switches 21c and 21k are switched by the switching control unit 21t.
When the contact becomes the contact b side, the proportional-integral controller 21
d is a detection value, and the minimum cutoff head h _po set by the second cutoff head setter 21j is a set value, and the output of the proportional-integral controller 21d changes so that the difference between the two becomes zero. Therefore, the electric pumps 12A, 1
The water discharged from 2B returns to the upstream of the electric pumps 12A and 12B via the bypass pipes 15A and 15B.

Then, the switching control section 21 t
s becomes the second signal (step ST1).
0), returning to step ST2.

As described above, according to one embodiment of the present invention, the electric pumps 12A and 12B rotate without stopping, that is, do not repeat starting and stopping, and even when water is supplied, the electric pumps 12A and 12B are switched from the low speed to the predetermined speed. Since it rises steeply, noise at the time of rising to a predetermined number of revolutions is reduced, and it is possible to cope with quick water supply, and the electric pump 12A,
12B can be prevented from being damaged by freezing. Since the electric pumps 12A and 12B rotate without repeating starting and stopping, the life of the mechanical seals and bearings of the electric pumps 12A and 12B becomes longer.
The maintenance cost of the electric pumps 12A and 12B can be reduced.

Further, when the first deadline head control is performed,
Since the check valves 13A and 13B are closed softly to maintain the pressure, the generation of noise due to the water hammer can be prevented, and the pressure tank becomes unnecessary or the pressure tank can be downsized. Can be configured. In addition, since the rotation speeds of the electric pumps 12A and 12B are in a long-term standby state with the second cutoff head control having a lower rotation speed than the first cutoff head control, the electric pump 1
The running cost when water is not supplied despite the continuous operation of 2A and 12B is reduced by the electric pump 1.
The cost can be reduced to a level comparable to stopping the 2A, 12B, and the operation is quiet.

[0057] Then, the throttle valve 17A, the bypass pipe 15A and 17B, since there is provided the 15B, it is possible to adjust the bypass flow rate q _B, the bypass pipe 15A, 15
The return path of B can be made versatile. Furthermore, when water is supplied under constant control of the estimated terminal pressure, the bypass pipe 1
Since 5A and 15B are closed to eliminate reflux, water can be supplied efficiently.

In the above-described embodiment, an example has been described in which water is supplied by the constant estimated end pressure control. However, by changing the constant estimated pressure control unit to a constant discharge pressure control unit, the water supply is performed by the constant discharge pressure control. It goes without saying that the present invention can be applied to an apparatus. Although the case where the number of the electric pumps 12A and 12B is two is shown, the number of the electric pumps may be one, or three or more, and the discharge side of each electric pump located upstream of each check valve may be used. Is connected to the suction side of the electric pump by a bypass pipe, that is, in addition to the connection method of the bypass pipe shown in FIG. 1, one end of the bypass pipe is connected to a discharge portion or a discharge end of the electric pump, The same effect can be obtained by connecting the other end of the bypass pipe to the suction section or suction end of the electric pump.

The motor valves 16A, 16B and the throttle valves 17A, 17B are provided in the bypass pipes 15A, 15B. However, the motor valves 16A, 16B and the throttle valve 1 are provided.
The same effect can be obtained even if 7A and 17B are omitted, and the return path formed by the bypass pipes 15A and 15B can be made versatile. Thus, the electric valve 16
When the valves A and 16B and the throttle valves 17A and 17B are omitted, FIG.
As shown in results in refluxing at all times bypass flow rate q _B, rated lift, since the bypass flow rate q _B operating point P ₅ is rated flow, the bypass as possible in consideration of the above conditions flow rate q _It is necessary to reduce power loss by reducing _B.

Further, the configuration of each control unit is merely an example, and it goes without saying that another configuration that functions similarly can be used. Further, the example in which the flow rate detecting means is constituted by the pressure detectors 18 and 20 has been described.
Can be used as flow rate detecting means. Then, the first lift is set to the set maximum deadline lift h
It has been described as _pomax, the maximum allowable deadline lift h _pmax
Less than, or the greater lift than the set minimum deadline lift h _Pomin, maximum allowed deadline lift h _pmax below, or to minimize deadline lift h _Pomin more lift setting, smaller than the set maximum deadline lift h _Pomin, minimum setting A similar effect can be obtained even if the head is larger than the cutoff head h _po .

Further, the second head has been described as the set minimum deadline head h _pomin , but the set maximum deadline head h _{pomin has} been described.
_pmax below, or to the minimum deadline lift _h pomin more lift settings, smaller than the set maximum deadline lift h _pmax,
The same effect can be obtained even when the head is _{equal to} or more than the set minimum deadline head h _pomin . Also, although the description has been given of the example of the water supply device connected to the water pipe, the electric pumps 12A, 12B
By connecting one end of each of the bypass pipes 15A and 15B connected to the water supply branch pipes 3A and 3B further upstream to the water receiving tank, the bypass pipes 15A and 15B can be applied to a water supply device that supplies water from the water receiving tank, and a similar effect can be obtained. it can. Thus, the bypass pipe 15
When one end of A, 15B is connected to the water receiving tank, the third (3)
The pressure h _i of the pressure detector 20 may be substituted for the pressure h _su in the equation.

Although the description has been given of the example in which the electric pumps 12A and 12B are operated at the same time, it is needless to say that the present invention can be applied to a water supply device for supplying water by alternately operating the electric pumps. Furthermore, a clock and a calendar are provided, and a time zone in which water is not used, such as from about 12:00 in the middle of the night when the water does not freeze to about 5:00 in the next morning, and a time zone in which starting and stopping are small, are stored. It is also possible to adopt a configuration in which the electric pumps 12A and 12B are stopped.

[0063] Further, it is configured to determine the output of the flow rate detecting means water requirements, may be configured to determine a pressure h _i of the pressure detector 20. A similar effect can be obtained even if the motor-operated valves 16A and 16B are opened only during the first cutoff head control. Furthermore, it is also possible to omit the bypass pipes 15A and 15B and to perform the first cutoff head control and then shift to the second cutoff head control.

In the above, an example has been described in which the elapse of each time is confirmed by referring to the timer, and the operation shifts to each dead-end head control. However, the electric pumps 12A and 12B or each temperature detecting means for detecting the temperature of water is described. It is also possible to adopt a configuration that shifts to each dead-end head control based on the output.

[0065]

As described above, according to the present invention, the first
The first head of the deadline head control unit is set to a head smaller than the allowable maximum deadline head and larger than the set maximum deadline head, a head lower than the allowable maximum deadline head, and a head larger than the set maximum deadline head, or a set maximum deadline head. Or the head is set to be smaller than the set maximum cutoff head and larger than the set minimum cutoff head, and is configured to wait at the first head, so that the electric pump rotates without stopping, that is, does not repeat starting and stopping, Also at the time of water supply, it steeply rises to a predetermined rotation speed.

Therefore, noise at the time of rising to a predetermined rotation speed is reduced, it is possible to quickly respond to a water supply request, it is possible to prevent the electric pump from being damaged by freezing, and to provide a water supply device. By installing the above components in the storage case, the entire water supply device can be prevented from freezing. Since the electric pump rotates without repeating starting and stopping, the service life of the mechanical seal and the bearing of the electric pump is extended, so that the maintenance cost of the electric pump can be reduced.

Further, when the first deadline head control is performed,
Since the check valve is closed softly to maintain the pressure, the generation of noise due to the water hammer can be prevented, and the pressure tank becomes unnecessary or the pressure tank can be downsized, so that the water supply device can be manufactured at low cost. At the same time, it can be made compact and the restrictions on the installation location can be eased.

Further, since the electric pump is configured to be in a standby state for a long time by the second cutoff head control at a lower rotational speed than the first cutoff head control, the electric pump is operated continuously. In addition, the running cost when water is not supplied can be reduced to a level comparable to stopping the electric pump, and the operation is quiet. Then, since the second head is set to a head close to the set minimum deadline head, the running cost when water is not supplied can be further reduced.

Further, since the second head is set to the minimum allowable cutoff head, the running cost when water is not supplied can be further reduced. In addition, since the throttle valve is provided in the bypass pipe, the flow rate of the bypass can be adjusted, and the return path formed by the bypass pipe can be made versatile. And when supplying water with constant control of the estimated end pressure, the bypass pipe was closed to eliminate reflux,
Water can be supplied efficiently.

[Brief description of the drawings]

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

FIG. 2 is a block diagram illustrating a configuration example of a control unit illustrated in FIG. 1;

FIG. 3 is a head-flow rate characteristic diagram for explaining the operation of the water supply device shown in FIGS. 1 and 2;

FIG. 4 is a flowchart of a switching control unit in the water supply device shown in FIGS. 1 and 2;

[Explanation of symbols]

Reference Signs List 1 water supply pipe 2 water supply main pipe 3A, 3B water supply branch pipe 11 check valve 12A, 12B electric pump 13A, 13B check valve 14A, 14B shutoff valve 15A, 15B bypass pipe 16A, 16B motor valve 17A, 17B throttle valve 18, Reference Signs List 20 pressure detector 19 flow switch 21 control unit 21a estimated terminal pressure setting unit 21b subtractor 21c selection switch 21d proportional integration controller 21e linear commander 21f first order lag element 21g square operation unit 21h constant multiplier 21i first deadline head setting unit 21j second shut-off lift setting device 21k selection switch 21l subtractor 21m, 21o constant setter 21n adder 21p~21r subtracter 21s comparator 21t switching control unit 22A, 22B inverter h _a actual head h _k pipe end pressure h _c fixed lift h _s presumed terminal pressure h _i pressure n ^* output n ^{* 2} output a constant h _poi output h _pomax setting maximum _cutoff head h _po setting minimum _cutoff head h _omin compensation head h _suc fixed loss head h _su pressure h _pos output q _min minimum flow q _B bypass flow h _pmax allowable Maximum deadline head _hpmin Allowable minimum deadline head

Claims (17)

[Claims] A non-return valve is provided in a water supply pipe downstream of an electric pump, and a water supply device supplies water by controlling the electric pump via an inverter by a constant estimated end pressure control unit. A bypass pipe connecting a discharge side of the electric pump located upstream of a valve to a suction side of the electric pump; and outputting a first signal when a flow rate downstream of the check valve is equal to or less than a minimum flow rate. A flow rate detecting means for outputting a second signal when the flow rate is larger than the minimum flow rate; and a first head having a head smaller than an allowable maximum cutoff head and larger than a set maximum cutoff head as the first head. A first cutoff head control unit that controls the electric pump via the first end-of-end pressure control unit when the flow rate detection unit continuously outputs a first signal for a first predetermined time. And a switching control unit from the control unit switches to the first shut-off lift controller is provided, the water supply device, characterized in that. 2. The water supply device according to claim 1, wherein the first head is equal to or less than the allowable maximum deadline head, is equal to or greater than the set maximum deadline head, and is equal to or less than the set maximum deadline head and is equal to or greater than the set minimum deadline head. A second deadline head control unit for controlling the electric pump via the inverter with the second head as a second head, the switching control unit including: the flow control unit, when the flow rate detection unit outputs the first signal after the first predetermined time. The water supply device further switches the control of the electric pump from the first dead-end head control unit to the second dead-end head control unit when a second predetermined time is output. 3. The water supply device according to claim 1, wherein the first head is a set maximum cutoff head. 4. The water supply apparatus according to claim 3, wherein the second pump controls the electric pump via the inverter by setting a head smaller than the set maximum cutoff head and equal to or larger than the set minimum cutoff head as a second head. A cutoff head control unit, wherein the switching control unit controls the electric pump by the first cutoff head when the flow rate detection unit outputs the first signal continuously after the first predetermined time for a second predetermined time. A water supply device, wherein the control unit switches to the second deadline head control unit. 5. The water supply device according to claim 1, wherein the first head is smaller than a set maximum cutoff head,
A water supply device characterized by being larger than a set minimum cutoff head. 6. The water supply device according to claim 5, further comprising a second cutoff head control unit that controls the electric pump via the inverter with the set minimum cutoff head being a second head, and the switching control unit. When the flow rate detecting means outputs the first signal continuously after the first predetermined time and continues for a second predetermined time, the control of the electric pump is performed from the first deadline head control unit to the second deadline head control unit. Switching, a water supply device. 7. The water supply device according to any one of claims 1 to 6, wherein a throttle valve is provided in the bypass pipe. 8. The water supply device according to claim 1, wherein an electric valve is provided on the bypass pipe, and the switching control unit is configured to control the electric pump using the constant estimated end pressure control unit. , The electric valve is closed only when the electric valve is controlled via an inverter. 9. A water supply device, wherein a check valve is provided in a water supply pipe downstream of the electric pump, and a constant discharge pressure control section supplies water by controlling the electric pump via an inverter. A bypass pipe connecting the discharge side of the electric pump positioned more upstream than the suction side of the electric pump; and outputting a first signal when a flow rate downstream of the check valve is less than or equal to a minimum flow rate. A flow rate detecting means for outputting a second signal when the flow rate is larger than the minimum flow rate; and a first head having a head smaller than an allowable maximum cut-off head and larger than a set maximum cut-off head as a first head. A first cutoff head control unit for controlling the electric pump, and when the flow rate detecting means continuously outputs the first signal for a first predetermined time, the control of the electric pump is controlled by the constant estimated end pressure. Part provided a switching control unit for switching to the first shut-off lift control unit from the water supply device, characterized in that. 10. The water supply device according to claim 9, wherein the first head is equal to or less than the allowable maximum deadline head, is equal to or larger than the set maximum deadline head, and is equal to or less than the set maximum deadline head and is equal to or larger than the set minimum deadline head. A second deadline head control unit for controlling the electric pump via the inverter with the second head as a second head, the switching control unit including: the flow control unit, when the flow rate detection unit outputs the first signal after the first predetermined time. The water supply device further switches the control of the electric pump from the first dead-end head control unit to the second dead-end head control unit when a second predetermined time is output. 11. The water supply device according to claim 9, wherein the first head is a set maximum cutoff head. 12. The water supply device according to claim 11, wherein a second head is set as a second head that is smaller than the set maximum cutoff head and equal to or larger than the set minimum cutoff head, and controls the electric pump via the inverter. A cutoff head control unit, wherein the switching control unit controls the electric pump by the first cutoff head when the flow rate detection unit outputs the first signal continuously after the first predetermined time for a second predetermined time. A water supply device, wherein the control unit switches to the second deadline head control unit. 13. The water supply device according to claim 9, wherein the first head is smaller than a set maximum cutoff head,
A water supply device characterized by being larger than a set minimum cutoff head. 14. The water supply device according to claim 13, further comprising a second cutoff head control unit that controls the electric pump via the inverter with the set minimum cutoff head being a second head, and the switching control unit. When the flow rate detecting means outputs the first signal continuously after the first predetermined time and continues for a second predetermined time, the control of the electric pump is performed from the first deadline head control unit to the second deadline head control unit. Switching, a water supply device. 15. The method according to claim 9, wherein:
The water supply device according to claim 1, wherein a throttle valve is provided in the bypass pipe. 16. The method according to claim 9, wherein:
In the water supply device described in the paragraph, an electric valve is provided in the bypass pipe, and the switching control unit controls the electric pump via the inverter by the estimated terminal pressure constant control unit or the estimated terminal pressure constant control unit. The water supply device, wherein the motor-operated valve is closed only when the electric power is supplied. 17. The method according to claim 1, wherein:
The water supply device according to claim 1, wherein one end of the bypass pipe connected to a suction side of the electric pump is connected to a water receiving tank.