JPH10176673A - Water supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress start/stop of an electric pump, and reduce noise by arranging a bypass pipe bypassing the electric pump, and changing control of the electric pump from an estimated terminal pressure constantly controlling unit into a pumping head control unit 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 pumps 12A, 12B are arranged on respective feed water branch pipes 3A, 3B. An electric valve 16 is interposed in a bypass pipe 15, and control is carried out by a control unit 21. Also pressure detectors 18, 20 and a flow switch 19 are arranged in the feed water main pipe 2, and the electric pumps 12A, 12B are controlled through inverters 22A, 22B on the basis of the output thereof. In the control unit 21, in the case where a first signal is outputted by a minimum flow rate and less by means of the flow switch 19, control of the electric pumps 12A, 12B is switched from an estimated terminal pressure constantly controlling unit into a pumping head controlling unit for controlling the electric pumps 12A, 12B serving the pumping head having setting 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 for supplying water by the above, a water supply pipe downstream of the check valve is connected to the suction side of the electric pump, a bypass valve for opening and closing the flow path of the bypass pipe, and a downstream of the check valve. A flow rate detecting 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 greater than the minimum flow rate; And a switch for switching the control of the electric pump from the constant estimated end pressure control section to the first head control section when the flow rate detecting means continuously outputs the first signal for the first predetermined time. Control unit and It is those provided.

[0008] A second head control unit for controlling the electric pump via an inverter by setting a head of 80% to 95% of the first head as a second head is provided. The switching control unit is provided. When the signal is continuously output for the first predetermined time, the control of the electric pump is switched from the estimated terminal pressure constant control section to the first head control section within the set time obtained by subtracting the first predetermined time from the allowable operation time, and the flow rate is detected. When the means continuously outputs the first signal after the first predetermined time and outputs the signal for the set time, the control of the electric pump is switched from the first head control unit to the second head control unit and the electric valve is closed. ,
Alternatively, a third head control unit for controlling the electric pump via an inverter as a third head with a head smaller than the second head and equal to or larger than the set minimum cutoff head provided through an inverter, wherein the switching control unit is provided and the flow rate detecting means is provided as a first head When the signal is continuously output for the first predetermined time, the control of the electric pump is switched from the estimated terminal pressure constant control section to the first head control section within the set time obtained by subtracting the first predetermined time from the allowable operation time, and the flow rate is detected. When the means continues to output the first signal after the first predetermined time and outputs the signal within the set time, the control of the electric pump is switched from the first head control unit to the third head control unit and the electric valve is closed. Or a third head control unit that controls the electric pump via an inverter as a third head with a head smaller than the second head and equal to or larger than the set minimum cutoff head, and a switching control unit, (2) Even after the head control unit controls the electric pump via the inverter, if the flow rate detection means continues to pull the first signal and outputs the signal for a predetermined time, the control of the electric pump is performed from the second head control unit to the third head control unit. It is desirable to adopt a configuration for switching to.

Next, a second invention is a water supply system in which a check valve is disposed in a water supply pipe downstream of the electric pump, and the electric pump is supplied by controlling the electric pump via an inverter in a constant estimated end pressure control section. In the device, a bypass pipe that connects a water supply pipe downstream of the check valve to the suction side of the electric pump, an electric valve that opens and closes the flow path of the bypass pipe, and a flow rate downstream of the check valve that minimizes First when flow rate is below
A flow rate detecting means for outputting a signal and outputting a second signal when the flow rate is larger than the minimum flow rate, and a second means for controlling the electric pump via an inverter by setting a head of 80% to 95% of the set head as a second head. A head control unit, and the flow rate detecting means
When a signal is continuously output for a predetermined time, the switching of the control of the electric pump from the estimated end pressure constant control unit to the second head control unit and closing of the electric valve is provided.

A third head control unit for controlling the electric pump via an inverter by setting a head smaller than the second head and equal to or larger than the set minimum cutoff head as a third head is provided. It is desirable that the control of the electric pump is switched from the second head control unit to the third head control unit when the first pump continues to output the first signal after the predetermined time and outputs the first signal for the predetermined time.

Next, a third invention is a water supply device in which a check valve is provided in a water supply pipe downstream of the electric pump, and the electric pump is supplied by controlling the electric pump via an inverter by a constant discharge pressure control section. , A bypass pipe that connects a water supply pipe downstream of the check valve to the suction side of the electric pump, an electric valve that opens and closes the flow path of the bypass pipe, and a flow rate downstream of the check valve is a minimum flow rate. A flow rate detection unit that outputs a first signal when the following is true, and outputs a second signal when the flow rate is greater than a minimum flow rate, and a second control method that controls an electric pump via an inverter by setting a head higher than a set head as a first head. A first head control unit, and a switching control unit that switches the control of the electric pump from the constant discharge pressure control unit to the first head control unit when the flow rate detection unit continuously outputs the first signal for the first predetermined time. It is.

A second head control unit is provided for controlling the electric pump via an inverter by using a head of 80% to 95% of the first head as a second head, a switching control unit, a flow detecting unit, and a flow detecting unit. When the signal is output continuously for the first predetermined time, the control of the electric pump is switched from the constant discharge pressure control unit to the first head control unit within a set time obtained by subtracting the first predetermined time from the allowable operation time, and the flow rate detection means Switches the control of the electric pump from the first head control unit to the second head control unit and closes the electric valve when the first signal is continuously output after the first predetermined time and within the set time. ,
Alternatively, a third head control unit for controlling the electric pump via an inverter as a third head with a head smaller than the second head and equal to or greater than the set minimum cutoff head provided via an inverter; When the signal is continuously output for the first predetermined time, the control of the electric pump is switched from the constant discharge pressure control unit to the first head control unit within a set time obtained by subtracting the first predetermined time from the allowable operation time, and the flow rate detection means Is the first
If the signal is continuously output within the set time after the first predetermined time, the control of the electric pump is switched from the first head control unit to the third head control unit, and the electric valve is closed, or A third head control unit that controls the electric pump via an inverter by setting a head smaller than the second head and equal to or greater than the set minimum deadline head as a third head, a switching control unit, and a second head control unit that controls the electric pump. Is controlled by the inverter, the control of the electric pump is switched from the second head control unit to the third head control unit when the flow rate detecting means continues to pull the first signal and outputs the first signal for a predetermined time. desirable.

A fourth invention is a water supply apparatus in which a check valve is provided in a water supply pipe downstream of the electric pump, and the electric pump is supplied by controlling the electric pump via an inverter by a constant discharge pressure control section. , A bypass pipe that connects a water supply pipe downstream of the check valve to the suction side of the electric pump, an electric valve that opens and closes the flow path of the bypass pipe, and a flow rate downstream of the check valve is a minimum flow rate. A flow rate detecting means for outputting a first signal at the time of the following, and outputting a second signal when the flow rate is larger than the minimum flow rate; an electric pump as an 80% to 95% of the set head as a second head; A second head control unit for controlling the electric pump from the constant discharge pressure control unit to the second head control unit when the flow rate detecting means continuously outputs the first signal for a predetermined time. Switching to close It is provided with a and a control unit.

A third head control unit for controlling the electric pump via an inverter by setting a head smaller than the second head and equal to or larger than the set minimum cutoff head as a third head is provided. It is desirable that the control of the electric pump is switched from the second head control unit to the third head control unit when the first pump continues to output the first signal after the predetermined time and outputs the first signal for the predetermined time.

The bypass pipe may be provided with a throttle valve, or one end of the bypass pipe connected to the suction side of the electric pump may be connected to the water receiving tank.

[0016]

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 line from the control unit to the motor-operated valve is not shown. FIG.
In the figure, 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 15 denotes a bypass pipe.
A, the water supply main pipe 2 downstream of 14B is connected to the electric pump 12
It is connected to the water supply main pipe 2 upstream of A. 16
Denotes a motor-operated valve disposed in the bypass pipe 15, which is controlled by a switching control unit 21w described later and opens and closes a flow path of the bypass pipe 15. Reference numeral 17 denotes a throttle valve provided in the bypass pipe 15.

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, which controls the electric pumps 12A and 12B via the inverters 22A and 22B and controls the electric valve 16 based on the outputs of the pressure detectors 18 and 20.

FIG. 2 is a block diagram showing the configuration of the control unit shown in FIG. The signal lines from the switching control unit to the 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.

[0021] 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 an output of the subtractor 21b or an output of a subtracter 21m 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
The output of 1 m is processed and output to the inverters 22A and 22B and a straight line commander 21e described later.

Reference numeral 21e denotes a linear commander, 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 is first lift setter for outputting a set lift h _ph as a first lift, 21j and the second lift setter for outputting a deadline lift h _pm as a second lift, 21k is set minimum deadline as a third lift 9 shows a third head setting device that outputs a head h _po .

Reference numeral 21l denotes a selection switch for selecting the output of the first head setting device 21i, the output of the second head setting device 21j, or the output of the third head setting device 21k.
21m represents a subtractor, set lift h _ph of the first lift setter 21i, deadline lift h _pm of the second lift setter 21j or the third lift setter 21k minimum setting deadlines lift h _po,
From the value obtained by subtracting the output h _poi of the constant multiplier 21h from the output.

Reference numeral 21n denotes a constant setting device, and a compensating head h
_omin is set. _{Reference numeral 21o denotes an} adder, which outputs the sum of the fixed head h _c output from the estimated terminal pressure setter 21a and the compensation head h _omin output from the constant setter _21n . Reference numeral 21p denotes a constant setting device for setting a fixed loss head h _suc of the check valve 11.

Reference numeral 21q denotes a subtractor, which outputs a value obtained by subtracting the fixed loss head h _suc of the constant setting device 21p from the pressure h _su detected by the pressure detector 18. 21r
Denotes a subtractor, and a subtractor 21q is obtained from the output of the adder 21o.
Is output by subtracting the output of. 21s
Denotes a constant multiplier, which outputs a value obtained by multiplying the output of the subtracter 21r by a constant a, which is a characteristic of the electric pumps 12A and 12B.

Reference numeral 21t denotes a square root calculator for outputting the square root of the output of the constant multiplier 21s as n ^* _min . Reference numeral 21u denotes a subtractor, which outputs a value obtained by subtracting the output n ^* of the primary delay element 21f from the output of the square root calculator 21t. Reference numeral 21v denotes a comparator for determining whether or not the output of the subtractor 21u is equal to or more than zero or negative, that is, whether or not 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 21w denotes a switching control unit, and a comparator 21v
And the selection switch 21 based on the output of
c and 211 are controlled as described later.
M, RAM, CPU, timer, etc.

The constant estimated end pressure control section comprises an estimated end pressure setting unit 21a, a subtractor 21b, and a proportional integral controller 21d. Then, the first head control unit includes:
Proportional-integral controller 21d, linear commander 21e, first-order lag element 21f, square calculator 21g, constant multiplier 21h, first
It comprises a head setting unit 21i and a subtractor 21m. Further, the second head control unit includes a proportional integral controller 21
d, a linear commander 21e, a first-order lag element 21f, a square calculator 21g, a constant multiplier 21h, a second head setting unit 21j, and a subtractor 21m.

The third head control section includes a proportional-integral controller 21d, a linear commander 21e, a first-order lag element 21f, a square calculator 21g, a constant multiplier 21h, and a third head setter 21.
k and a subtractor 21m. The flow rate detecting means includes an estimated terminal pressure setter 21a, a subtractor 21
b, proportional-integral controller 21d, linear commander 21e, first-order lag element 21f, constant setting units 21n, 21p, adder 21
o, subtracters 21q, 21r, 21u, constant multiplier 21
s, a square root calculator 21t, and a comparator 21v.

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.

[0032] In FIG. 3, A is presumed terminal pressure constant control curve, R represents total loss curves and stop loss of friction loss between the throttle valve 17 of the bypass pipe 15, P ₁ is a putative terminal pressure constant control curve A q = 1.0, 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, in P ₃ the first lift control Operating point, P ₄ is operating point in the second lift control, P _4
5 indicates an operating point in the third head control. The operating point P ₃ is located at the intersection of the estimated terminal pressure constant control curve A and the loss curve R, and the operating points P ₄ , P ₅ , P ₆ are located on the loss curve R.

FIG. 4 is an allowable operating time characteristic diagram in the first head control. This characteristic is achieved by the electric pumps 12A, 12B
When the closing lift is performed at the time, the electric pumps 12A, 12A
The shaft power of B is changed with respect to the rated shaft power, and the bypass flow rate q _B of the bypass pipe 15 is 5% or 10% of the allowable flow rate T _{B with} respect to the rated flow rate of the electric pumps 12A and 12B.
Is shown in the unit method.

[0034] Here, to describe the acceptable operation time T _B, by the bypass flow rate q _B less, the electric pump 12A, because the work is almost zero given to water 12B, the electric pump 12A, 12B shaft power Is mostly consumed in the stirring of the water. Thus, the electric pump 1
When most of the shaft power of the shafts 2A and 12B is consumed for agitation of water, the temperature of water, impellers, packings, bearings, mechanical seals, motor coils, etc. in the electric pumps 12A and 12B rises. .

[0035] Thus, small amounts of bypass flow rate q _B at the electric pump 12A, the allowable operation time T _B for the the 12B allowable temperature below the electric pump 12A at that time, 12
If the shaft power of B is known, it can be obtained. This shaft power can be determined by equation (1), the allowable operating hours for the bypass flow rate q _B, (bypass flow rate q _B +
The allowable operation time for the minimum flow rate q _min ) / 2 is obtained,
Shorter the permissible operating time and T _B.

[0036]

(Equation 1)

Here, l ₀ : power of the closing shaft (p.
u. ) = L ₀ / L _N (pu) L ₀ : power of the shut-off shaft of the electric pumps 12A and 12B (k
W) L _N: Teikakujiku power (kW) h _o:. Deadline lift _{(p.u) <(h a +} h k)
_{(P.u.) h a: (.} P.u) actual head _{= H a / H N (p.u.} ) h k: (. P.u) pipe end pressure _{= H K / H N (p} . . u) H _a: actual head (m) H _k: the tube end pressure (m) H _N: electric pump 12A, 12B of the rated lift (m) η _qB: bypass flow rate q _B when the (p.u.) electric pump efficiency (p.u.) q _B: bypass flow rate in the second lift control (p.u.) q _min: bypass flow rate in the deadline lift control (p.
u. )

[0038] Thus, the shaft power of the electric pump 12A, the bypass flow rate q _B is also a flow rate of 12B as a parameter, the relationship between the allowable operation time T _B to rise to an acceptable temperature, the test value for each electric pump to be used, As shown in FIG. 4, it can be obtained for each electric pump based on experimental values and the like.

Next, 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 lift control, the operating point, the operating point P _3. Further, at the second lift control, the operating point, the set lift h _ph at the operating point P ₃ 9
Corresponds to 0% in the operating point P ₄ deadline lift h _pm.
When this deadline lift h _pm, although backflow occurs slightly by lift decreases, the check valve 13A,
13B can be closed gently.

Then, in the third head control, the head becomes the set minimum cutoff head h _po . The set minimum cutoff head h _po is a value satisfying the expression (2), and the electric pump 1
The value is set to a value as close as possible to the allowable minimum cutoff head _{hpmin at} which the mechanical seals 2A and 12B can be lubricated and the frictional resistance is minimized.

[0041]

(Equation 2)

[0042] 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 Lift (pu)

The maximum allowable _cutoff head _hpmax is determined by the electric pump 1 with the check valves 13A and 13B closed.
This is a head in which the temperature rise of 2A and 12B is not more than an allowable value. The allowable minimum cutoff head _hpmin is a _cutoff head at which the mechanical seals of the electric pumps 12A and 12B can be lubricated to minimize the frictional resistance. In the case of the third 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 enables the electric pumps 12A and 12B to operate continuously, the allowable minimum cutoff head _hpmin is limited for a limited time.
A, 12B can be operated continuously.

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).

[0045]

(Equation 3)

Here, n: speed (pu) of electric pumps 12A and 12B = N / N _N (pu) N: speed (rpm) of electric pumps 12A and 12B N _N : electric pump 12A, 12B of the rated speed (rpm) h _a: actual head (p.u.) h _k: the tube end pressure _(p.u.) h omin: compensating lift (p.u.) h _su: pump push lift (p. u.) = 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.) a: constant of the electric pump 12A, 12B

(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. 5 is a flowchart of the switching control section in the water supply device shown in FIGS. In FIG. 5, ST1 to ST13 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 21v determines that the flow rate is the minimum flow rate q _min
More second signals are output. First, the switching control unit 21w determines whether the output of the comparator 21v is a first signal having the minimum flow rate q _min or less (step ST1), and determines whether the output of the comparator 21v is the first signal having the minimum flow rate q _min or less. 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, 21l
Is switched to the contact a side, the electric valve 16 is closed (step ST2), and the process returns to step ST1.

[0050] Thus selection switch 21c, the 21l is contact a control of the switching control section 21w, 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. Accordingly, the constant estimated terminal pressure is controlled so as to move between the operating point P ₁ on the curve A in FIG. 3 and the operating point P ₂ .

[0051] By all the faucet is closed, the flow rate falls below the minimum flow rate q _min, comparator 21v
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 21v in this way, the switching control unit 21w confirms that the signal from the comparator 21v 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 21v is continued. (Step ST5).

In the determination in step ST5, the comparator 21
If the first signal from v is not continued, the process proceeds to step ST
Returning to 1, if the first signal from the comparator 21v 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 motor-operated valve 16, and
A timer is set (step ST6).

[0053] and in this way selection switch 21c is the contact b under the control of the switching control section 21w, the detection value output of the proportional integral controller 21d, the set value set lift h _ph of the first lift setter 21i, The first head control is such that the output of the proportional integral controller 21d changes so that the difference between the two becomes zero, and the water discharged from the electric pumps 12A and 12B is:
The air is recirculated upstream of the electric pumps 12A and 12B via the bypass pipe 15.

Then, the switching control unit 21 w
It is determined whether the first signal from v is continuing (step ST7). If the first signal from comparator 21v is not continuing, the process returns to step ST2, and the first signal from comparator 21v is continued. long as it determines whether the set time minus with reference to timer allowable operation time from T _B of the first predetermined time has elapsed (step ST8).

If it is determined in step ST8 that the set time has not elapsed, the process returns to step ST7. If the set time has elapsed, the selection switch 211 is switched to the contact b side, and the motor-operated valve 16 is closed. At the same time, a timer is set (step ST9). Thus, the selection switch 2
When 1l becomes the contact b side under the control of the switching control unit 21w and the motor-operated valve 16 is closed, the output of the proportional-integral controller 21d is a detected value, the cutoff head h of the second head setter 21j.
The second head control is performed in which the output of the proportional-plus-integral controller 21d changes so that _pm is a set value and the difference between the two becomes zero, and the check valves 13A and 13B close slowly.

Then, it is determined whether the first signal from the comparator 21v continues (step ST10).
If the first signal from 1v is not continued, step S
Returning to T2, if the first signal from the comparator 21v continues, it is determined whether a second predetermined time, for example, 2 seconds, has elapsed with reference to the timer (step ST11). If it is determined in step ST11 that two seconds have not elapsed, the process returns to step ST10. If two seconds have elapsed, the selection switch 211 is switched to the contact c side (step ST1).
2) Wait until the signal from the comparator 21s becomes the second signal (step ST13), and the third head control is performed. When the signal from the comparator 21v becomes the second signal (step ST13), the process returns to step ST2.

As described above, according to the 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 supplying water 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, after _reaching the minimum flow rate q _min , the second
Until the head control is completed, a long-term standby state in which the electric power of the electric pumps 12A and 12B is large is provided, so that it is possible to quickly respond to a water supply request. In the second head control, the check valves 13A and 13B are closed softly to maintain the pressure, so that noise caused by the water hammer can be prevented, and the pressure tank becomes unnecessary.
Since the pressure tank can be downsized, the water supply device can be made compact.

Since the electric pumps 12A and 12B are in a long-term standby state by the third lift control at a low speed, the running is performed when the electric pumps 12A and 12B are continuously operated but no water is supplied. The cost can be reduced to a level comparable to stopping the electric pumps 12A and 12B, and the operation is quiet.
Further, the throttle valve 17 so provided in the bypass pipe 15, it is possible to adjust the bypass flow rate q _B, it can have versatility return passage by the bypass pipe 15.

In the above-described embodiment, an example has been described in which water is supplied by constant control of estimated terminal pressure. However, by changing the constant control unit of estimated terminal pressure to a constant discharge pressure control unit, water supply is performed by constant control of discharge pressure. It goes without saying that the present invention can be applied to an apparatus. And the electric pumps 12A and 12B are 2
Although the case of one electric pump was shown, even one electric pump or three electric pumps
If the configuration is such that the water supply pipe downstream of the check valve is connected to the suction side of the electric pump, that is, in addition to the connection method of the bypass pipe shown in FIG. The same effect can be obtained by connecting the other end of the bypass pipe to the suction portion or the suction end.

[0061] Further, the electric pump 12A, the operating point P ₃ lift from the operating point P ₂ of 12B, P ₄ via operating point P a
Described in example the transition to _5, but the operating point from the operating point P ₂ P
If direct transition to _5, or is shifted from the operating point P ₂ to the operating point P _3, or is shifted via the operating point P ₃ from the operating point P ₂ to the operating point P _4, operation from the operating point P ₂ or is shifted to the operating point P ₅ by way of the point P _3, is shifted from the operating point P ₂ or is shifted to the operating point P _4, via the operating point P ₄ from the operating point P ₂ to the operating point P ₅ A similar effect can be obtained.

Further, although the description has been given of the example in which the throttle valve 17 is provided in the bypass pipe 15, a similar effect can be obtained even if the throttle valve 17 is omitted. The configuration of each control unit is merely an example, and it goes without saying that another configuration that functions similarly may be used. Further, the example in which the flow rate detecting means is constituted by the pressure detectors 18 and 20 has been described, but it goes without saying that the flow switch 19 can be used as the flow rate detecting means.

[0063] Also, have been described second lift as 90% of the set lift h _ph, 80% of the set lift h _ph the second lift to 9
It is set between 5% and can also obtain the same effect with a larger lift than the set lift h _ph operating point P ₃ of the second lift. Although the electric valve 16 is closed at the time of water supply, it is also possible to keep the electric valve 16 open at the time of water supply.

When the motor-operated valve 16 is kept open even when water is supplied, as shown in FIG. 3, the motor is always circulated at the bypass flow rate q _B , and the bypass at the rated head and the rated flow rate is performed. since the flow rate q _B increases, it is possible to improve the in the small amount of bypass flow rate q _B as possible in consideration of the above conditions to reduce the power loss, the life of the electric valve 16.

Although the description has been given of the example of the water supply device connected to the water supply pipe, one end of the bypass pipe 15 connected to the water supply main pipe 2 upstream of the electric pumps 12A and 12B is connected to the water receiving tank. Also, the present invention can be applied to a water supply device for supplying water from a water receiving tank, and a similar effect can be obtained. When one end of the bypass pipe 15 is connected to the water receiving tank, the pressure h _su of the force detector 20 is used as the pressure h _{su in the} equation (3).
_i can be substituted.

Furthermore, the example in which the electric pumps 12A and 12B are simultaneously operated has been described. However, it is needless to say that the present invention can be applied to a water supply device in which the electric pumps are alternately operated to supply water. In addition, a clock and a calendar are provided, and a time zone in which water is not used, such as from 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 the start and stop are small, are stored. The electric pumps 12A and 12B may be configured to be stopped, and the electric pumps 12A and 12B may be stopped at midnight during freezing.
From around the time to around 5 o'clock the next morning,
It is also possible to forcibly set the first head control at intervals at which freezing can be prevented, and to prevent the electric pumps 12A and 12B from freezing.

[0067] 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. Then, by referring to the timer, the elapse of each time is confirmed, and the description has been given of the example in which the process shifts to each dead-end head control, but the electric pumps 12A, 12B,
Alternatively, it is also possible to adopt a configuration in which a transition is made to each dead-end head control based on the output of each temperature detecting means for detecting the temperature of water.

[0068]

As described above, according to the present invention, the electric pump is controlled at the first lift, instead of stopping the electric pump. It can take a long time and can respond quickly to water supply requests. Then, the electric pump is rotated without stopping, that is, the starting and stopping are not repeated, and the water supply is configured to steeply rise from the low-speed rotation speed to the predetermined rotation speed even when water is supplied, so that noise at the time of rising to the predetermined rotation speed is reduced. It becomes smaller and can respond quickly to water supply demands, preventing the electric pump from being damaged by freezing, and installing the components of the water supply device in the storage case, so that the entire water supply device Can also be prevented from freezing.

Further, since the electric pump rotates without repeating starting and stopping, the 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, in the second head control, the check valve is closed softly to maintain the pressure, so that 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. Therefore, the water supply device can be manufactured at low cost, can be configured compactly, and the restriction on the installation location can be reduced.

Since the electric pump enters the long-term standby state by the third head control at low speed rotation, the running cost when water is not supplied despite the continuous operation of the electric pump is reduced by the electric pump. The cost can be reduced to a level comparable to the case of stopping, and the operation is quiet. Further, when the third head is the minimum allowable deadline 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.

[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 an allowable operation time characteristic diagram in the first head control.

FIG. 5 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 15 bypass pipe 16 electric valve 17 throttle valve 18, 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 operator 21h Constant multiplier 21i First head setting unit 21j Second head setting unit 21k third lift setting device 21l selection switch 21m subtracter 21n, 21p constant setter 21o adder 21q, 21r subtractor 21s constant setter 21t square-root calculator 21u subtractor 21v comparator 21w switching control unit 22A, 22B inverter h _a real lift h _k pipe end pressure h _c fixed fried h _s presumed terminal pressure h _i pressure n ^* output n ^{* 2} outputs a constant h _poi output h _ph set lift h _pm deadline lift h _po set minimum deadline lift h _Omin compensating lift h _suc fixed loss lift h _su pressure n ^* _min square root q _min minimum flow rate q _B bypass flow rate T _B allowable operation time

Claims (14)

[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 that connects the water supply pipe downstream of the valve to the suction side of the electric pump; an electric valve that opens and closes a flow path of the bypass pipe; and a flow rate downstream of the check valve that is equal to or less than a minimum flow rate. Controlling the electric pump via the inverter, by outputting a first signal at the time of, and outputting a second signal when the flow rate is greater than the minimum flow rate; A first head control unit, and when the flow rate detecting means continuously outputs a first signal for a first predetermined time, the control of the electric pump is switched from the estimated terminal pressure constant control unit to the first head control unit. That a switching controller is provided, the water supply device, characterized in that. 2. The water supply device according to claim 1, further comprising a second head control unit that controls the electric pump via the inverter by setting a head of 80% to 95% of the first head as a second head. The switching control unit is configured to control the electric pump only within a set time obtained by subtracting the first predetermined time from the allowable operation time when the flow rate detection unit continuously outputs the first signal for the first predetermined time. Is switched from the constant estimated end pressure control section to the first head control section, and when the flow rate detection means continuously outputs the first signal after the first predetermined time and outputs the signal within the set time, the control of the electric pump is performed. Is switched from the first head control unit to the second head control and the electric valve is closed. 3. The water supply device according to claim 1, wherein a third head, which is smaller than the second head and equal to or more than a set minimum dead-head head, is used as the third head and controls the electric pump via the inverter. A control unit, wherein when the flow rate detection unit continuously outputs the first signal for the first predetermined time, the switching control unit controls the electric motor for a set time obtained by subtracting the first predetermined time from an allowable operation time. When the control of the pump is switched from the estimated terminal pressure constant control section to the first head control section, and the flow rate detecting means continuously outputs the first signal after the first predetermined time and outputs the first signal within the set time, the electric motor is controlled. The water supply device, wherein control of a pump is switched from the first head control unit to the third head control unit, and the electric valve is closed. 4. The water supply device according to claim 2, wherein a third head, which is smaller than the second head and equal to or greater than a set minimum cutoff head, is controlled via the inverter. Providing a head control section, the switching control section, after the second head control section controls the electric pump via the inverter, the flow rate detection means continues to pull the first signal and output for a predetermined time ,
The water supply device, wherein control of the electric pump is switched from the second head control unit to the third head control unit. 5. A water supply device, wherein a non-return valve is provided in a water supply pipe downstream of the electric pump, and the electric pump is supplied by controlling the electric pump via an inverter by a constant estimated end pressure control section. A bypass pipe that connects the water supply pipe downstream of the valve to the suction side of the electric pump; an electric valve that opens and closes a flow path of the bypass pipe; and a flow rate downstream of the check valve that is equal to or less than a minimum flow rate. The first pump outputs a first signal at the time of, and outputs a second signal when the flow rate is greater than the minimum flow rate; and the electric pump sets the head of 80% to 95% of the set head as the second head, A second head control unit that controls the inverter via an inverter, and when the flow rate detecting unit continuously outputs the first signal for a predetermined time, the control of the electric pump is performed from the estimated terminal pressure constant control unit to the second head. It switched control unit, provided a switching control unit for closing the electric valve, it water supply apparatus according to claim. 6. The pump according to claim 5, wherein the third pump is configured to control the electric pump via the inverter as a third pump which is smaller than the second pump and is equal to or larger than a minimum cutoff head. A control unit, wherein the switching control unit controls the electric pump from the second head control unit to the third control unit when the flow rate detection unit continuously outputs the first signal after the predetermined time and outputs the first signal for the predetermined time. A water supply device that switches to a head control unit. 7. A water supply device, wherein a check valve is disposed in a water supply pipe downstream of the electric pump, and the electric pump is supplied by controlling the electric pump via an inverter by a constant discharge pressure control unit. A bypass pipe connecting the water supply pipe downstream of the electric pump to a suction side of the electric pump, an electric valve for opening and closing a flow path of the bypass pipe, and a flow rate downstream of the check valve being equal to or less than a minimum flow rate. A first flow rate detecting means for outputting a first signal and a second flow rate signal when the flow rate is larger than the minimum flow rate; A first head control unit, and a switch for switching the control of the electric pump from the constant discharge pressure control unit to the first head control unit when the flow rate detection unit continuously outputs the first signal for a first predetermined time. It provided the control unit, water supply and wherein the. 8. The water supply apparatus according to claim 7, wherein a second head control unit that controls the electric pump via the inverter by setting a head of 80% to 95% of the first head as a second head. The switching control unit is configured to control the electric pump only within a set time obtained by subtracting the first predetermined time from the allowable operation time when the flow rate detection unit continuously outputs the first signal for the first predetermined time. Is switched from the constant discharge pressure control section to the first head control section, and when the flow rate detection means continuously outputs the first signal after the first predetermined time and outputs the signal within the set time, the control of the electric pump is performed. The water supply device, switching from the first head control unit to the second head control unit and closing the electric valve. 9. The water supply device according to claim 7, wherein a third head, which is smaller than the second head and is equal to or larger than a set minimum cutoff head, as a third head, controls the electric pump via the inverter. A control unit, wherein when the flow rate detection unit continuously outputs the first signal for the first predetermined time, the switching control unit controls the electric motor for a set time obtained by subtracting the first predetermined time from an allowable operation time. When the control of the pump is switched from the constant discharge pressure control section to the first head control section, and the flow rate detection means continuously outputs the first signal after the first predetermined time and outputs the signal within the set time, the electric pump The control of the water supply is switched from the first head control unit to the third head control unit, and the electric valve is closed. 10. The water supply apparatus according to claim 8, wherein a third head, which is smaller than said second head and is equal to or greater than a set minimum cutoff head, as said third head, controls said electric pump via said inverter. Providing a head control section, the switching control section, after the second head control section controls the electric pump via the inverter, the flow rate detection means continues to pull the first signal and output for a predetermined time ,
The water supply device, wherein control of the electric pump is switched from the second head control unit to the third head control unit. 11. A check valve is provided in a water supply pipe downstream of the electric pump, and the electric pump is controlled by a discharge pressure constant control unit.
In a water supply device for supplying water by controlling through an inverter, a bypass pipe that connects the water supply pipe downstream of the check valve to a suction side of the electric pump, and an electric motor that opens and closes a flow path of the bypass pipe A valve; a flow rate detection means for outputting a first signal when a flow rate downstream of the check valve is equal to or less than a minimum flow rate, and outputting a second signal when the flow rate is greater than the minimum flow rate; A second head control unit for controlling the electric pump via the inverter with a head of% to 95% as a second head, wherein the flow rate detecting means continuously outputs the first signal for a predetermined time, A water supply device, comprising: a control unit that switches control of an electric pump from the constant discharge pressure control unit to the second head control unit and closes the electric valve. 12. The pump according to claim 11, wherein the third pump is configured to control the electric pump via the inverter as a third pump which is smaller than the second pump and is equal to or greater than a set minimum cutoff pump. A control unit, wherein the switching control unit controls the electric pump from the second head control unit to the third control unit when the flow rate detection unit continuously outputs the first signal after the predetermined time and outputs the first signal for the predetermined time. A water supply device that switches to a head control unit. 13. The method according to claim 1, wherein:
The water supply device according to claim 1, wherein a throttle valve is provided in the bypass pipe. 14. 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.