JPH10103251A - Automatic water supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong the pump suspension period by effectively utilizing a water supply tank for saving energy. SOLUTION: In an automatic water supply device provided with avariable speed pump and a water supply tank in a water supply and discharge passage, when the flow rate in the water supply and discharge passage is more than a given value Qa, the variable speed pump performs pressure control (control to keep discharge pressure in constant, control to maintain probable end pressure in constant, etc.), and when the flow rate mentioned above is less than the given value Qa, the variable speed pump is controlled to be a nearly fixed speed pump using a given computing equation for effectively utilizing the water supply tank.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic water supply device such as a water supply system in which a variable speed pump and a water supply tank are arranged in a water supply / distribution path.

[0002]

2. Description of the Related Art As such an automatic water supply device, there are a combination of a fixed speed pump and a water supply tank, and a device having a variable speed pump and a water supply tank. The former type has a problem that the operation becomes inoperable when the pressure fluctuation on the pump suction side is large, and the latter type is generally used recently. An example of the automatic water supply device according to FIG. 2 is shown. That is, the variable speed pump 2 variably controlled by the variable speed control device 1 such as an inverter sends water from the pump well 7 to the water supply tank 3 and the water supply / distribution pipe 6. In addition, 4 is a flow meter, 5 is a pressure gauge, and 8 is an adjustment / control device.

FIG. 3 shows a conventional control example in such a configuration. That is, the adjustment / control device 8 monitors the pressure signal P of the pressure gauge 5 and controls the rotation speed of the variable speed pump 2 via the variable speed control device 1 so that the pressure signal P becomes a constant value Pc (discharge pressure constant control). ). On the other hand, the variable speed pump 2 stops its operation when the flow rate measured by the flow meter 4 becomes substantially zero, and starts operation when the pressure signal P of the pressure gauge 5 becomes P1. Therefore, the water supply tank 3 uses only the capacity corresponding to the difference ΔP between the discharge pressure set value Pc and the starting pressure P1.

[0004]

As described above, the water supply tank is not effectively used in the control shown in FIG.
There is a problem that the pump stop period is short and energy saving is not achieved. Therefore, an object of the present invention is to make effective use of a water supply tank, extend a pump stop period, and save energy.

[0005]

According to the present invention, there is provided an automatic water supply apparatus having a variable speed pump and a water supply tank arranged in a water supply / distribution path. When the flow rate of the water distribution path is larger than a predetermined value, pressure control (constant discharge pressure control or constant estimated end pressure control) is performed by the variable speed pump, and when the flow rate is smaller than a predetermined value, a predetermined arithmetic expression is used. The variable speed pump is controlled so as to approximate a fixed speed pump.

[0006]

FIG. 1 is an explanatory view of an embodiment of the present invention. The system applied is the same as that of FIG. That is, the water flowing in the water supply / distribution pipe 6 is detected by the flow meter 4, and if this is equal to or higher than the predetermined flow rate Qa, a predetermined calculation is performed by the adjustment / control device 8 based on the pressure signal P from the pressure gauge 5, Through the control device 1, constant control of the discharge pressure of the variable speed pump 2 is performed. Note that, instead of the discharge pressure constant control, the estimated terminal pressure constant control may be performed.

On the other hand, if the flow rate is equal to or less than Qa, the adjustment / control device 8 turns on the variable speed pump 2 via the variable speed control device 1 according to the following arithmetic expressions (1) and (2). The control is turned off, and the control approximates that of the fixed speed pump. _{P = P 1 + P 0 {} 1- (Q N / Q a) K} ... (1) Here, P: pressure target P _1: night up water when necessary pressure = pump start pressure P _0: Deadline at P Pressure to be added to ₁ Q _N : Night water supply (Q _N ≤ Q _a ) Q _a : Night maximum water supply K: Coefficient (2; assumed) P ₂ = P ₁ + P ₀ ｛1-(Q ₂ / Q _a ) ^K ｝… (2) where, P ₂ : pump stop pressure Q ₂ : water supply when pump stops (Q ₂ = Q _a / 4 to Q _a
/ 3)

As described above, the variable speed pump 2
Stops at the pressure P _{2 as} shown by the solid line in FIG.
It will be controlled to operate at ₁ . Therefore, the capacity of the water supply tank 3 corresponding to the difference ΔP ′ between the pressures P ₂ and P ₁ is used, and the water supply tank 3 can be more effectively used than before. The above pressures P ₁ and P ₂ depend on the water supply and distribution pipe conditions (actual head, required terminal pressure, pipe loss, etc.).
It can be changed as P ₁ ′, P ₂ ′.

[0009]

According to the present invention, there is obtained an advantage that, by effectively utilizing the water supply tank, the period during which the pump is stopped can be lengthened and energy saving can be realized. In addition, this invention,
It can be widely applied to booster pumps and the like in direct supply water.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram for explaining a first embodiment of the present invention.

FIG. 2 is a configuration diagram illustrating a general example of an automatic water supply device.

FIG. 3 is an explanatory diagram of a conventional control method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Variable speed control device, 2 ... Variable speed pump, 3 ... Water supply tank, 4 ... Flow meter, 5 ... Pressure gauge, 6 ... Supply and distribution pipe, 7 ... Pump well, 8 ... Adjustment / control device.

Claims (2)

[Claims] 1. An automatic water supply apparatus comprising a variable speed pump and a water supply tank arranged in a water supply / distribution path, a variable speed control device for controlling the variable speed pump, and a flow rate for detecting a flow rate and a pressure in the water supply / distribution path. And a detection signal from the flow meter and the pressure gauge, and when the flow rate of the water supply / distribution path to the variable speed control device is larger than a predetermined value, pressure control is performed by the variable speed pump. And an adjusting / control device for controlling the variable speed pump to approximate a fixed speed pump by a predetermined arithmetic expression when the flow rate is smaller than a predetermined value. 2. The automatic water supply device according to claim 1, wherein the pressure control is a discharge pressure constant control or an estimated terminal pressure constant control.