JPH09268978A - Variable speed water supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide such a variable speed water supply device as being capable of accurately detecting the discharge pressure abnormally lowered condition of a pump to avoid additional and parallel-off operation in error. SOLUTION: A water supply device has pumps 13a, 13b rotationally driven by a motor, a check valve provided on the discharge side of the pumps 13a, 13b, a pressure detector 18 and a pressure tank 16 provided in the downstream of the check valve, small-amount-of-water detecting means 20a, 20b for pumps, a variable speed means to drive the pumps at variable speeds and a control means 17 to perform variable speed operation control and addition and parallel- off of the pumps. Depending on combined conditions that the rotating speed of at least one pump, when operated, reaches a preset speed and water is detected to be small in amount by the small-amount-of-water detecting means 20a, 20b, a means provided for the control means 17 additionally operate the other pump being stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable speed water supply apparatus capable of operating two or more pumps in parallel, and particularly, a control system configuration capable of stably performing addition / disconnection operations of pumps operating in parallel. Regarding

[0002]

2. Description of the Related Art FIG. 1 shows a system outline of a variable speed water supply system provided with two pumps. For example, an inflow pipe 12 is connected to a water distribution pipe 11 which is a main pipe of water supply, and two pumps 13a and 13b are connected to the inflow pipe 12. A water meter (not shown) is connected to the inflow pipe 12 to measure the amount of water used. A discharge pipe 15 connected to the terminal water supply device 14 is connected to the discharge side of each pump 13a, 13b.

A pressure tank 16 is connected to the discharge pipe 15. A discharge pressure detector 18 for detecting the discharge pressure of the pump in the discharge pipe 15 and sending this pressure signal to the control means 17 is provided on the discharge side of the pumps 13a and 13b. The pumps 13a and 13b are each connected to a commercial power source of, for example, three-phase 200V.
It is equipped with variable speed means 19a, 19b consisting of an electric motor equipped with a voltage converter (inverter), and is driven at a variable speed.

The control means 17 includes a discharge pressure detector 18
A signal is sent to each of the variable speed means 19a and 19b based on the above signal, and the rotation speed of each pump 13a and 13b is feedback-controlled so as to reach a predetermined control target pressure. As the speed control, PI (proportional integration) control is used because of the stability of normal control.

Further, each pump 13 is attached to the discharge pipe 15.
Located on the discharge side of a, 13b, small water amount detecting means 20a, 20b, which are, for example, flow switches, and check valves 21a, 21b for backflow prevention are respectively interposed, and the small water amount detecting means 20a, The signal from 20b is sent to the control means 17. When the small amount of water detection means detects that the customer side 14 has almost no water consumption, the control means 17 controls the pump to be stopped in order to prevent the pump from shutting off and save energy. Be done.

By the way, the two pumps 13a and 13b are
The rotation speed is controlled so that one unit or two units maintain the control target pressure in accordance with the amount of water to be sent. When the amount of water used is small, only one unit is operated, the amount of water used increases, and when the operation of one pump is insufficient to maintain the control target pressure, that is, the rotation speed of one pump 13a during operation is When the maximum rotation speed is reached, the operation of the second pump 13b is started (additional input). Then, after that, when the amount of water used on the consumer side decreases, the rotation speed of the pump 13b decreases, and the control target pressure can be maintained by one pump, one of the two pumps can be maintained. Pump 13a or 13
It is designed to stop the parallel disconnection of b.

FIG. 3 (A) shows a control flow during additional operation of the conventional pump. When the amount of water used increases and it is not enough to operate one pump, that is, in order to keep the pump discharge pressure at a predetermined target pressure, as shown in FIG. When the maximum rotation speed command is output to and the additional delay timer is activated, and the maximum speed command is continuously output during the operation of this timer, the second pump 13b is additionally operated. .

FIG. 3 (B) shows a control flow when the conventional pump is disengaged. After that, the amount of water used decreased,
One pump 13a is operating at a fixed speed, and the rotational speed of the pump 13b that is operating at a variable speed is reduced to a small water amount state, and when the flow switch 20b is closed, that is,
As shown in FIG. 3 (B), when the flow switch 20b is closed and the disconnection delay timer is activated and the flow switch 20b is continuously closed during the operation of the timer,
The operation of one of the two pumps 13b is stopped (disconnected).

By the way, when the discharge pressure decreases due to a pump abnormality or the like, the discharge pressure is below a predetermined pressure value, the pump rotation speed is below a predetermined rotation speed, the flow switch is closed, and the operating current is below a predetermined operating current. An abnormal drop in discharge pressure is detected by combining conditions, and an alarm is issued. This alarm is output when the detection delay timer operates for a predetermined period of time, and during that period, a predetermined condition continues.

The state in which the discharge pressure of the pump is abnormally lowered includes, for example, a case where the valve on the suction side of the pump is erroneously closed and the pump is operated. here,
The detection delay timer used for detecting the abnormal discharge pressure drop is controlled by the additional delay timer or the disconnection delay timer so that the abnormal discharge pressure drop is not detected in a transient operating state such as when the pump is started. The time is set long.

[0011]

However, in the above-mentioned conventional example, when the pump pressure during one unit operation is abnormal due to some reason and the discharge pressure is lowered, the maximum rotation speed command is issued to this pump. Will be issued. As described above, the delay timer for abnormal decrease in discharge pressure has a long time. On the other hand, since the delay timer for performing the additional operation is short, the pump additional operation is performed before the abnormal discharge pressure drop alarm is issued. If the amount of water used is small, immediately disconnect the pump and add the additional water.
There was a problem that the disconnection was repeated.

Further, when two or more pumps are operating and the pump discharge pressure abnormally drops for some reason, the flow switch of the pump during variable speed operation is closed. Similarly, the delay timer for the pump disconnection operation is shorter than the detection delay timer for the abnormal pressure drop alarm, so the pump disconnection operation is performed before the abnormal discharge pressure decrease alarm is issued. When the amount of water used is large enough to operate with one pump, there is a problem that the additional operation is immediately performed and the addition / disconnection is repeated.

This is because, as described above, the delay timer for the discharge pressure abnormal low alarm output is longer than the additional operation delay timer and the disconnection operation delay timer, and moreover, the operation is performed after the added pump and disconnection operation. If the operating state of the pump being operated is normal, the conditions for abnormally lowering the discharge pressure are not met, and no alarm is output.

Here, it is conceivable that the additional operation delay timer or the disconnection operation delay timer is made longer than the delay timer for the discharge pressure abnormal drop alarm output, but in this case, the response to the addition or disconnection becomes slow. This leads to a decrease in discharge pressure and wasteful operation of a plurality of pumps.

The present invention has been made in view of the above-mentioned circumstances, and is a variable speed water supply apparatus which accurately detects an abnormally lowered discharge pressure of a pump and prevents an erroneous addition / disconnection operation. The purpose is to provide.

[0016]

A variable speed water supply system of the present invention comprises a plurality of pumps which are rotationally driven by an electric motor, a check valve provided on the discharge side of the pumps, and a check valve provided downstream of the check valves. A pressure detector and a pressure tank provided, a small water amount detecting means for the pump, a variable speed means for driving the pump at a variable speed, and a control means for controlling the operation of the pump at a variable speed and additionally disconnecting the pump. In the variable speed water supply device, the control means detects that the rotational speed of the pump has reached a predetermined speed during operation of at least one pump and that the small water quantity detection means detects that the pump is not in the small water quantity state. It is characterized in that it is provided with means for additionally operating another pump that is stopped depending on the weighting condition.

According to the present invention thus constructed, when one pump is in operation, if the amount of water used increases to the extent that one pump runs short, the rotational speed of the pump becomes the maximum rotational speed, and the flow rate is increased. Switch (Means for detecting small amount of water)
Remains open. Therefore, the normal addition operation of the pump can be performed. Further, if the discharge pressure drops for some reason during operation of one pump, the rotational speed of the pump reaches the maximum rotational speed, but the flow switch closes. Therefore, by setting both of these as weighted conditions, even if the discharge pressure is reduced due to a pump abnormality, the additional pump operation is not performed, and it is possible to prevent repeated additional disconnection.

Another variable-speed water supply device of the present invention is a plurality of pumps that are rotationally driven by an electric motor, a check valve provided on the discharge side of the pumps, and a pressure detection device provided on the downstream side of the check valves. And a pressure tank, and a small water amount detecting means of the pump,
In a variable speed water supply device comprising a variable speed means for driving the pump at a variable speed and a control means for controlling the operation of the pump at a variable speed and additionally disconnecting the pump, the control means is a small amount of water when operating a plurality of pumps. The detection means detects that the pump to be disconnected is in a small amount of water, and the discharge pressure detector causes the discharge pressure to be above a predetermined value. It is characterized in that it is provided with a means for.

According to the present invention having the above-described structure, when a plurality of pumps are operating and the amount of water used is reduced to the extent that one pump can be operated, the flow switch (small water amount detecting means) is closed and the discharge is performed. The pressure remains almost constant. Therefore, a normal disconnection operation can be performed. If the amount of water used is sufficient and the pump discharge pressure drops abnormally while multiple pumps are in operation, the flow switch of the pump will close,
Moreover, the discharge pressure becomes lower than the predetermined value. Therefore, by setting both of these as weighted conditions, it is possible to prevent the pump disconnection operation from being repeated and the pump disconnection addition operation to be repeated due to an abnormal decrease in the discharge pressure.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. In addition, the outline of the system which is the premise of the pump operation control in each of the following embodiments is as shown in FIG. Inflow pipe 12 connected to water distribution pipe 11, and a plurality of pumps 13a, 13b connected to this inflow pipe 12
And a discharge pipe 15 connected to the discharge side of each of the pumps 13a and 13b and connected to the terminal water supply device 14, and a discharge pressure detector provided on the discharge pipe 15 for detecting the discharge pressure of the pumps 13a and 13b. 18 and each of the pumps 13
Variable speed means 19 for respectively driving a and 13b at variable speeds
a, 19b and the control means 1 for controlling the operation of the pumps 13a, 13b at a variable speed by PI control and additionally disconnecting
7 and are provided.

Further, each pump 13 is attached to the discharge pipe 15.
Located on the discharge side of a, 13b, the small water amount detecting means 20a,
20b and check valves 21a, 21b are interposed, and signals from the small water amount detecting means 20a, 20b are sent to the control means 17.

FIG. 2A is a control flow chart showing the first embodiment of the present invention. In this embodiment, the control means 17 shown in FIG. 1 is provided with a maximum rotation speed of the pump and a small water amount detection means (flow switch) when at least one pump is operating.
It is provided with means for additionally operating another pump which is stopped depending on the weighted condition of the open state.

That is, as shown in the figure, for example, the amount of water used increases while one pump 13a is operating at a variable speed, and the maximum rotation speed command is issued to this pump 13a in order to maintain the target discharge pressure. Output and flow switch 20a
When the open state continues for the set time of the additional delay timer, the pump addition operation, that is, the pump 13
The operation of b is started.

That is, when the discharge pressure of the pump abnormally drops for some reason, the rotation speed command increases and reaches the maximum rotation speed, but the discharge pressure does not occur and the flow switch is closed. Therefore, the additional operation of the pump is not performed without satisfying the weighting condition described above. Therefore, an alarm is issued after the elapse of the delay timer time for the output of abnormal discharge pressure alarm output, and the abnormal decrease in discharge pressure can be reliably detected without erroneous additional operations.

FIG. 2B is a control flow chart showing the second embodiment. In this embodiment, the control means 1 shown in FIG. 1 is used.
In Fig. 7, when the amount of water used is reduced during the operation of a plurality of pumps and it is in time for the operation of one pump, the discharge pressure and the condition of the small water amount detection means (flow switch) are weighted so that one of It is equipped with a means for stopping the pump of the platform from being disconnected.

That is, as shown in the figure, for example, the amount of water used decreases during parallel operation of the two pumps 13a and 13b, and the pump 13a operates at a fixed speed, but the pump 13b operating at a variable speed. The rotation speed decreases and the flow switch 20b closes. At that time, the discharge pressure is 0.9 of the target pressure.
When the state of not less than 5 times continues during the set time of the parallel delay timer, the pump parallel operation, that is, the pump 1
The operation of 3b is stopped.

When the amount of water used is sufficient and the pump discharge pressure drops abnormally while a plurality of pumps are operating, the flow switch is closed, but the discharge pressure drops, so
Does not meet the above weighting conditions. Therefore, in this case,
No pump disconnection operation is performed, and repeated disconnection additions are prevented. Therefore, an alarm is issued after the delay timer for the output of abnormal discharge pressure alarm output has elapsed, and an abnormal decrease in discharge pressure can be reliably detected without erroneous disconnection operation.

As described above, the erroneous addition operation and disconnection operation are not performed when the discharge pressure is lowered due to a pump abnormality or the like, and the pump addition and disconnection operation can be accurately and responsively performed. Further, in each of the above embodiments, 2
Although the example applied to the variable speed water supply device provided with three pumps is shown, it is needless to say that the same can be applied to the variable speed water supply device provided with three or more pumps. In addition, each of the above embodiments has been described with respect to an example of a variable speed water supply device directly connected to a mains of a water supply, but the same applies to a variable speed water supply device that temporarily stores water in a water tank or the like and then supplies it to a demand destination. Of course, it can be applied.

[0029]

As described above, according to the present invention, in the variable speed water supply device having two or more pumps, the discharge pressure due to a pump abnormality or the like is generated when the pump adding operation or the pump disconnecting operation is performed. It is possible to accurately detect the abnormally lowered state and prevent erroneous pump addition or pump disconnection operation at the time of such an abnormality.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a system configuration of a variable speed water supply device.

FIG. 2A is a control flow chart of a pump addition operation of the first embodiment of the present invention, and FIG. 2B is a control flow chart of a pump disconnection operation of the second embodiment of the present invention.

3A is a control flow diagram of a conventional pump addition operation, and FIG. 3B is a control flow diagram of a conventional pump disconnection operation.

[Explanation of symbols]

 12 inflow pipe 13a, 13b pump 15 discharge pipe 16 pressure tank 17 control means 18 discharge pressure detector 19a, 19b variable speed means 20a, 20b small water amount detection means (flow switch)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G05D 13/62 G05D 13/62 C (72) Inventor Tomoharu Teshima 4-chome, Fujisawa, Kanagawa Prefecture No. 1 stock company Ebara Densan

Claims (2)

[Claims] 1. A plurality of pumps rotationally driven by an electric motor, a check valve provided on the discharge side of the pumps, a pressure detector and a pressure tank provided on the downstream side of the check valve, and a pump of the pump. In a variable speed water supply device comprising a small amount of water detection means, a variable speed means for driving the pump at a variable speed, and a control means for controlling the operation of the pump at a variable speed and additionally disconnecting the pump, the control means is at least When one pump is in operation, the other pumps are additionally operated under the weighted condition that the rotation speed of the pump reaches a predetermined speed and that the small water amount detecting means detects that the pump is not in the small water amount state. A variable-speed water supply device, which is provided with a means for making it possible. 2. A plurality of pumps rotationally driven by an electric motor, a check valve provided on the discharge side of the pumps, a pressure detector and a pressure tank provided downstream of the check valve, and a pump for the pumps. In a variable speed water supply apparatus comprising a small amount of water detection means, a variable speed means for driving the pump at a variable speed, and a control means for controlling the operation of the pump at a variable speed and additionally disconnecting the pump, the control means comprises a plurality of One of the pumps in operation is detected by the small water amount detecting means when the pump is operating, and the discharge pressure detector detects that the discharge pressure is at a predetermined value or more. A variable-speed water supply device comprising means for stopping the parallel disconnection of the pump.