JPH05133381A - Control method for automatic water supplier - Google Patents

Abstract

PURPOSE:To provide a control method for an automatic water supplier, practical at a low cost, wherein a pump expected to stop in a parallel operation mode can be automatically and surely paralleled off as necessary regardless of constitution of the pump itself. CONSTITUTION:In a control method for an automatic water supplier of switching an operation mode to alternate operation A and parallel operation B, a pump in the parallel operation mode B is selectively and intermittently operated to decelerate as shown by Al A2 A3. In the selected pump, since a delivery pressure and a delivery flow amount are decreased by decelerating operation, the pump is stopped, when the delivery flow amount (q) is decreased to a predetermined value Q0 or less, in a parallel-off region and not stopped, since a water pressure H in a supply water flow path is decreased to the above- mentioned predetermined value H1 or less before the delivery flow amount is decreased to the predetermined value Q0 or less, in a nonparallel-off region, and the pump is stopped when decreased to the parallel-off region while decelerating operation is intermittently repeated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is to automatically start a plurality of pumps connected in parallel in order when the water pressure in a water supply channel drops below a predetermined value and to stop them when a discharge flow rate falls below a predetermined value. The present invention relates to a method for controlling a water supply device.

[0002]

2. Description of the Related Art In a control method for an automatic water supply system, which automatically converts the operation mode of a plurality of pumps connected in parallel into alternate operation and parallel operation in relation to the amount of water supply, the water pressure in the water supply passage is generally predetermined. When the value drops below a certain value, the pumps that are stopped are started in order according to the start signal sent from the pressure detection unit, and if the water supply amount decreases during parallel operation, either the flow rate, pressure, or current, etc. The pumps are stopped in order according to the disconnection signal sent from the detector,
The last pump is stopped in response to a stop signal sent from the flow rate detector when the amount of water supply decreases below a predetermined value.

[0003]

Among the conventional detectors for transmitting the disconnection signal, the flow detector for transmitting when the amount of water supply decreases below a predetermined value has a complicated and large structure and is costly. Not only is there a difficulty in terms of surface and size, but also the head loss is large. Further, the pressure detection unit that transmits when the discharge pressure rises above a predetermined value is not suitable for practical use because the discharge pressure hardly rises even when the water supply amount decreases in a device equipped with a pressure adjusting means such as a pressure reducing valve. Furthermore, the current detection unit that transmits when the motor input current drops below a predetermined value is mainly applied to centrifugal pumps, but it is practical when considering fluctuations in power supply voltage, variations in pump characteristics, and variations in motor ratings. I can't say.

The present invention has been made to solve the above-mentioned problems, and automatically and reliably disconnects a pump scheduled to be stopped in the parallel operation mode regardless of the configuration of the pump itself. It is an object of the present invention to provide a control method of an automatic water supply device that can be performed at low cost and is practical.

[0005]

According to the present invention, a plurality of pumps connected in parallel are sequentially activated when the water pressure in a water supply channel drops below a predetermined value, and stopped when a discharge flow rate drops below a predetermined value. In the control method of the automatic water supply device, the pump in the parallel operation mode is selectively and intermittently decelerated.

[0006]

In the above structure, the discharge pressure and the discharge flow rate of the selected pump to be stopped are reduced by decelerating the pump. Therefore, when the total amount of water supply has decreased to a region requiring the parallel disconnection (hereinafter referred to as the parallel disconnection region), the pump is stopped when the discharge flow rate decreases below the predetermined value. Further, when the total water supply amount is in a region that does not require the parallel disconnection (hereinafter referred to as the non-parallel disconnection region), the water pressure in the water supply channel is reduced before the discharge flow rate of the pump decreases to the predetermined value or less. The pump is not stopped because it falls below the predetermined value, and is stopped when the water supply amount decreases to the off-line region while intermittently repeating the deceleration operation.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. For easy understanding, it is assumed that two pumps having substantially the same characteristics and connected in parallel are operated alternately and in parallel, and the configuration is illustrated in FIG. 1 and the pumping characteristics are illustrated in FIG. 2, respectively. However, the present invention is not limited to these.

In FIG. 1, the suction side of the pumps 1 and 2 is in the water receiving tank 3, and the discharge side is through the flow rate detectors 4 and 5 and the water supply passage 6 is provided.
Respectively connected to. An accumulator tank 7 and a pressure detector 8 are connected to the water supply passage 6. The flow rate detection units 4 and 5 respectively send stop signals when the discharge flow rates of the pumps 1 and 2 decrease below a predetermined value (hereinafter referred to as stop flow rate). The pressure detection unit 8 sends a start signal when the water pressure in the water supply passage 6 drops below a predetermined value (hereinafter, referred to as start pressure). The control unit 9 includes means for processing the stop signal and the start signal, a timer and other required means, and starts and stops the drive motors 10 and 11 for the pumps 1 and 2.
It is configured so that the start / stop sequence, speed, etc. can be automatically controlled. The shift control in this case may be continuous or stepwise, and the control method is the electric motor 10,
It may be appropriately set according to the type, output, and other characteristics of 11.

Next, a method of controlling the apparatus configured as described above will be described with reference to FIGS. 2 (A) and 2 (B). In addition, A and B in FIG. 2 show the respective characteristic curves in the alternate operation mode of one unit and the parallel operation mode of two units.

When both the pumps 1 and 2 are stopped and the water pressure H in the water supply passage 6 falls below the starting pressure H1 and a starting signal is input from the pressure detecting section 8 to the control section 9,
For example, the pump 1 is started according to a preset order, and while H ≧ H1, the alternate operation mode A with the pump 2 is performed.
become. In this state, when the discharge flow rate Q of the pump 1 (or 2) decreases below the stop flow rate Q0 and a stop signal is input from the flow rate detection unit 4 (or 5) to the control unit 9, the pump 1 (or 2) However, when H≤H1 and the start signal is input from the pressure detection unit 8 to the control unit 9 (arrow a), the stopped pump is started and the two parallel operation modes B are stopped. become.

When a predetermined time T1 (for example, 1 min) elapses after switching to the parallel operation mode B, for example, the pump 2 is decelerated through the control unit 9 in accordance with a preset order. Therefore, its pumping characteristics are shown in Figure 2.
As illustrated in (B), A1 → A2 →
As shown in A3, the total water supply Q is within the disconnection region (Q0 ≤
Q <Q1, Q1 is the starting pressure H in the alternating operation mode A
If the amount of water supply corresponds to 1 (for example, arrow b), the discharge flow rate q of the pump 2 also decreases as q1 → q2 → q3. Therefore, when q ≦ Q0, the flow rate detection unit 5 to the control unit 9 The pump 2 is stopped in response to the stop signal input to, and the mode is switched to the alternating operation mode A. That is, in this case, the stop signal acts as a disconnection signal for disconnecting the pump 2.

If the total water supply amount Q is within the non-disconnecting region (Q1≤Q <Q2, Q2 is the water supply amount corresponding to the starting pressure H1 in the parallel operation mode B) after the elapse of the predetermined time T1, the pump 2 Before the discharge flow rate q of H decreases to q≤Q0.
Since .ltoreq.H1 (for example, arrow c), the pump 2 is returned to the normal operation in response to the start signal input from the pressure detection unit 8 to the control unit 9, and is continuously maintained in the parallel operation mode B. Then, after a predetermined time T2 (for example, 3 minutes) has elapsed, the pump 2 is decelerated again, and the disconnection control similar to the above is repeatedly tried until the parallel operation mode B is disconnected. If necessary, the predetermined times T1 and T2 may be appropriately extended according to the elapsed time T3 (for example, 10 minutes or more) from the time when the parallel disconnection control is performed until the time when the parallel operation mode B is switched to next. May be.

As described above, by intermittently decelerating the pump scheduled to be disconnected in the parallel operation mode B, the necessity of disconnection is automatically determined, and the total water supply amount Q is within the disconnection region. Since it is automatically stopped in some cases, the flow rate detector may be of a small capacity corresponding to an individual pump, so it is small and low in cost, and should be reliably disconnected regardless of the configuration of the pump itself. You can If the deceleration operation means is applied even when the pump is started, it is possible to contribute to the reduction of excessive noise.

The present invention is not limited to the above-mentioned embodiment. For example, a pressure value of a plurality of stages is set in the control unit 9 so that it can be compared with the output signal of the pressure detection unit 8, and one of them is set. If the pressure is equal to the starting pressure H1 and higher than the others (for example, H2 in FIG. 2), the discharge pressure decreases to H2 when the total water supply amount Q is within the disconnection region during the disconnection control trial. When this is done, that is, the deceleration operation is interrupted earlier than H1, so that gear shifting is performed more smoothly. Besides, various modifications and applications are possible within the scope of the gist of the present invention.

[0015]

As described in detail above, according to the present invention, a pump scheduled to be stopped in the parallel operation mode can be automatically and surely disconnected as needed regardless of the configuration of itself. It is possible to provide a low-cost and practical method for controlling an automatic water supply device.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of the present invention.

FIG. 2 is a diagram for explaining the operation of the embodiment,
(A) shows a regular pumping characteristic, and (B) shows a pumping characteristic at the time of deceleration operation in the parallel row region.

[Explanation of symbols]

1, 2 ... Pump, 4, 5 ... Flow rate detection unit, 6 ... Water supply flow path,
8 ... Pressure detection unit, 9 ... Control unit, 10, 11 ... Electric motor, A
... Alternate operation mode, B ... Parallel operation mode, H1 ... Starting pressure, Q0 ... Stop flow rate.

Claims (1)

[Claims] 1. A method of controlling an automatic water supply apparatus, wherein a plurality of pumps connected in parallel are started in sequence when the water pressure in a water supply channel drops below a predetermined value, and stopped when the discharge flow rate drops below a predetermined value. A method for controlling an automatic water supply device, which selectively and intermittently decelerates pumps in a parallel operation mode.