JPS6156436B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling the number of pumps in operation, which can automatically set the number of pumps in operation according to the internal pressure of a pressure tank.

A water supply system that has multiple pumps connected in parallel and a pressure tank connected to the discharge side of these pumps, and the number of pumps in operation is variably controlled according to the flow rate or pressure of water flowing out from the pressure tank. Since the system can increase the amount of water supplied without increasing the volume of the pressure tank, it is often adopted in small-scale buildings, etc., where space factors are particularly important. However, when the number of pumps in operation is controlled in accordance with the flow rate of water, it is difficult to obtain an appropriate flow rate detection means in terms of cost and reliability. In addition, with conventional means of controlling according to pressure, it is necessary to increase the number of pressure switches as well as the number of pumps, making adjustment difficult and reducing reliability. To avoid this, timers and other time-limiting elements are also used. However, there are drawbacks such as poor responsiveness.

The present invention has been made based on the above-mentioned circumstances, and its purpose is to provide a device that is simple and easy to handle, has good responsiveness, and high reliability.
Another object of the present invention is to provide a method for controlling the number of pumps in operation without increasing the frequency of operation.

In the present invention, a predetermined sampling period is set in which the internal pressure of the pressure tank is repeatedly detected at a predetermined period, and a full detection state in which the internal pressure is equal to or higher than the upper limit value or lower than the lower limit value throughout one sampling period, and one sampling period are set. A partial detection state in which the internal pressure is above the upper limit value or below the lower limit value in a part of the section is stored in the memory for each sampling section, and a partial detection state in which the internal pressure is above the upper limit value or below the lower limit value in a part of the section is stored in the memory device, and after the sampling section in which neither the whole surface nor the partial detection state is stored. If any detection state is stored in the sampling period, the number of pumps in operation is changed by one unit, and after this change command signal is sent out, the full or partial detection state in the same direction continues. The present invention is characterized in that when the entire surface detection state is stored after being stored, the number of operating pumps is changed by one unit every predetermined number of repetition cycles.

The present invention will be explained below based on an illustrated embodiment.

In Figure 1, a plurality of (n units) pumps P ₁ , _{P 2} . A pressure sensor 5 is connected to a pressure tank 4 connected to this water pipe 3. This pressure detector 5 generates an insufficient signal when the internal pressure of the pressure tank 4 is below a predetermined lower limit value L, and generates an excess signal when it is above a predetermined upper limit value H, and when the internal pressure exceeds the lower limit value L. It is configured so that no signal is generated when it is in an intermediate region below the upper limit H (see FIG. 3).

The output signal of the pressure detector 5 is guided to a determination section 6 as shown in FIG. A sampling section setting section 7 connected to the determining section 6 has an appropriate clock pulse generator, timing setting device, etc., and is configured to be able to set a predetermined sampling section at every predetermined repetition period. The repetition period includes a sampling period and a subsequent processing time, and may further include a pause time if necessary. The sampling period is set to, for example, several seconds to several tens of seconds depending on the operating characteristics of the water supply system, whereas the processing time can be several milliseconds, so in the following, the repetition period and the sampling period are approximately equal. Explain as a thing.
Note that in this embodiment, no pause time is set.

The determination section 6 is equipped with an appropriate memory, and this memory stores, for each sampling period, a full detection state in which the signal input from the pressure detection section 5 appears over the entire sampling period, and a partial detection state. Which of the partial detection states appearing in the above is stored is stored together with the distinction between the insufficient signal and the excess signal. Then, when a partial or full surface detection state is stored in a sampling period following the sampling period in which neither the full surface detection state nor the partial detection state is stored, a platform change command signal is generated. Furthermore, if the entire surface or partial detection state in the same direction is continuously stored after this change command signal is generated, and then the entire surface detection state is stored, the predetermined value set in the magnification setters 8 and 9 The device is configured to generate a platform change command signal every several repetition periods. When the output signal of the pressure detector 5 is an insufficient signal, the content of the change command signal is an increase command to increase the number of pumps in operation, and when the output signal is an excess signal, the content is a command to reduce the number of pumps. Needless to say, it is a thing. Then, the predetermined number of repetition cycles corresponding to the increase and decrease command signals, respectively, are set in the magnification setting devices 8 and 9 based on the characteristics of the pumps P ₁ to _{P o} and the lower limit value L and the value set in the pressure detector. It is set in advance according to the upper limit value H and the like.

The output signal of the determination section 6 is guided to the control section 11 via the processing section 10. The processing section 10 receives the platform change command signal, feeds back the platform change information to the determination section 6, and receives information regarding the pumps _P1 to _P0 via the control section 11. In the case of a command to increase the number of pumps, the pump that stopped the earliest or the one with the shortest extended operating time is selected from among the waiting pumps, and a start command signal is sent to this pump. In addition, in the case of a command to reduce the number of units, the pump that started the earliest or the one with the longest extended operating time is selected from among the pumps in operation, and a stop command signal is sent to this pump.

The control unit 11 starts or stops the pump in accordance with the start command signal and stop command signal. In this case, the number of pumps is increased or decreased by one unit in response to one change command signal, and the number of pumps forming one unit may be single or plural. Further, the control unit 11 is configured to individually check the operating status of the pumps P ₁ to _{P o} , perform processing such as stopping a pump with an abnormality, and feed back this information to the processing unit 10. There is.

Note that the above-mentioned logical operation processing, except for power control, is processed by a program set in a control device such as a microcomputer or a programmable logic controller.

In the apparatus configured as described above, the internal pressure P of the pressure tank 4 is in the intermediate area (H>P>L) in any sampling period _S0 , as illustrated in FIG. If it is less than the lower limit L during S ₁ , then in the sampling period S ₁ it will be in the full detection state on the underpressure side, and in the previous sampling period S ₀ it will not be in either the full or partial detection state. Therefore, at the end of the sampling period S ₁ , the determination section 6 sends out an additional pump command signal, and as a result, one unit of pumps is additionally operated via the processing section 10 and the control section 11 .

Even though the number of units was increased in this way, P still remained low in the next sampling period S ₂ and S ₃ .
If the <L state continues, the magnification setting section 8
If the number of repetition cycles set is 2, for example, one pump is added at the end of the sampling period _S3 . In this case, S ₁ and S ₂ may be partial detection.

At the end of the next sampling period _S4 , P<L still holds, and the previous three cycles are in the state of full-scale detection in the same direction, but two cycles have still elapsed since the generation of the previous platform change command signal. Therefore, no increase command signal is generated at the end of the sampling period _S4 .

If the internal pressure P moves to the intermediate area in the next sampling period _S5 , the change command signal will not be sent and will continue to change.

Also, in the middle of the sampling period _S7 , P<L again
When the partial detection is memorized, at the end of S ₈ , S ₁
Similarly, an additional signal is sent out.

Thereafter, detection continues at S ₈ and S ₉ , but since S ₉ after the predetermined number of sampling repetition cycles of 2 is a partial detection, no further increase command signal is sent.
As a result of these, the internal pressure P increases and the sampling period
If P>H in _S12 , then at the end of _S12 , a one-unit unit reduction command signal is sent. Then, as shown in _S12 to _S14 , the internal pressure P reaches the upper limit value H.
In S ₁₄ , if the transition is near ,
Even though two cycles have passed since the platform changing control was performed at the end of S ₁₂ , the platform reduction command signal is not sent because it is a partial detection in S ₁₄ , and the platform reduction is not performed until full detection is memorized in S ₁₅ . A command signal is sent.
Therefore, even if there is a transition from _S11 to _S14 , an excessive change signal is not sent, and there is no fear that the frequency of change control will increase.

In addition, as shown in the broken line shown in FIG. 3, for example, S ₁₁
If a sudden change in the amount of water supply causes a short-term pressure change that is inappropriate to ignore as noise and exceeds the upper limit H, partial detection is performed, so the final stage of _S11 is The number of units will be reduced.

In such a case, since this can occur when the average level of the internal pressure P has already reached the vicinity of the upper limit value H, such a change can be considered a normal operation, and even if the change is made, it is not necessary. There is no problem. Then, this section is processed as a partial detection section, and a change of platform is determined based on whether the subsequent partial and full detection sections are continuous, thereby making it possible to prevent high-frequency change of platforms.

As can be seen from the above explanation, when the amount of water flowing out from the water pipe 3 increases and the internal pressure P of the pressure tank 4 decreases, the number of operating pumps P ₁ to _{P o} changes according to the output signal of the pressure detection section 5. When the internal pressure P increases as the water supply amount decreases, the number of operating units is reduced. Moreover, once the platform has been changed, even if a portion and the entire surface are detected in the same direction, the platform is not immediately changed again, and these changes are made by carefully observing the changes in at least two sampling sections after the above-mentioned change of platform. If detections in the same direction are continuously stored, the platform is changed at every predetermined repetition period, so the frequency of platform changes does not increase. The change command signal that commands an increase or decrease in the number of pumps in operation is sent out in accordance with the relationship between the deviation state of the internal pressure P from the intermediate region and the sampling region.
By appropriately setting the sensitivity and sampling period of the pressure detector 5, it is possible to obtain optimal responsiveness for the water supply amount. Furthermore, since the number of operating pumps is variably controlled based on the internal pressure of the pressure tank, and therefore the water supply pressure, the operating efficiency of the pumps does not decrease even if the water supply flow rate varies significantly. Furthermore, since only one pressure detection section is required and the upper and lower limits can be adjusted separately, the adjustment does not take much time, is simple and easy to handle, and is highly reliable.

Moreover, controlling the number of pumps in operation as described above,
Because it can be electrically processed based on a program set in a microcomputer or programmable logic controller, it does not require a large number of mechanical parts, resulting in a simple structure and great economic effects. .

It should be noted that the present invention is not limited to the above-mentioned embodiments only, and various modifications and applications can be made within the scope of the gist thereof. For example, the repetition period may be shifted so that the time when the tank internal pressure deviates from the intermediate area is set as the initial stage of the sampling period to improve responsiveness.

As described above, the present invention sets a predetermined sampling period in which the internal pressure of a pressure tank is repeatedly detected at a predetermined period, stores the full detection state and the partial detection state for each sampling period, and stores both the full detection state and the partial detection state. If any detection state is stored in the next section of the sampling section in which the detection state of The device is characterized in that when the partial detection state is stored continuously and then the full detection state is stored, the device is changed at every predetermined number of repetition cycles. Therefore, it is possible to obtain good responsiveness that is optimal for the water supply system, maintain good pump operation efficiency even when the water supply flow rate fluctuates significantly, and reduce the frequency of pump operation. be able to. In addition, it is easy to handle, has high reliability, and has many excellent practical effects.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is a piping system diagram, FIG. 2 is a block diagram of a control circuit, and FIG. 3 is a diagram for explaining the operation. 4...Pressure tank, 5...Pressure detector, 6...
Judgment section, 7... Sampling section setting section, 8, 9
...Magnification setting section, 10... Processing section, 11... Control section, P ₁ to P _o ... Pump, H... Upper limit value, L...
Lower limit value, P...Internal pressure of the pressure tank.

Claims (1)

[Claims] 1. The number of pumps connected in parallel is decreased when the internal pressure of the pressure tank connected to the discharge side of these pumps is above a predetermined upper limit, and is increased when it is below a predetermined lower limit. A predetermined sampling period is set in which the internal pressure of the pressure tank is repeatedly detected at a predetermined period, and a full detection state in which the internal pressure is equal to or higher than the upper limit value or lower than the lower limit value throughout one sampling period, and one sampling period are set. The partial detection state in which the internal pressure is above the upper limit value or below the lower limit value in a part of the area is stored in the memory for each sampling interval, and the detection state after the sampling interval in which neither the entire surface nor the partial detection state is stored is stored in the storage unit. If any detection state is stored in the sampling period, the number of pumps in operation is changed by one unit, and after this change command signal is sent, the full or partial detection state in the same direction is continued. A method for controlling the number of pumps in operation, characterized in that when a full-scale detection state is stored after being stored, the number of pumps in operation is changed by one unit every predetermined number of repetition cycles.