JP2004316434A - Variable speed supply water device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correctly conduct control even when highest rotation speed and the level of suction water are unknown in conducting estimated terminal pressure constant control using a cascade pump. <P>SOLUTION: A controller 11 for a motor 4 to drive the cascade pump 2 automatically rewrites a map in accordance with the highest rotation or shutoff pressure by operation so as to determine highest rotation speed, thereby efficient estimated terminal pressure constant control is conducted. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a variable speed water supply device including a cascade pump, a pressure sensor provided on a discharge side of the cascade pump, a motor for driving the cascade pump, and a controller for controlling a rotation speed of the pump.
[0002]
[Prior art]
BACKGROUND ART Conventionally, in order to supply water to a home, an automatic water supply device using a cascade pump is often used to supply water or well water stored in a water receiving tank. The reason for using a cascade pump is preferable in terms of energy saving and low noise. Such a conventional automatic water supply device is equipped with an inverter and performs discharge pressure constant control (for example, see Patent Document 1).
[0003]
In addition, in order to meet a demand for obtaining a predetermined pressure and water amount in a home at the end of a pipe, constant control of estimated end pressure is known (for example, see Patent Documents 2, 3, and 4).
[0004]
Patent Document 1 Japanese Patent Application Laid-Open No. 10-288185 Patent Document 2 Japanese Patent Application Laid-Open No. 60-142097 Patent Document 3 Japanese Patent Application Laid-Open No. 60-156959 Patent Document 4 Japanese Patent Application Laid-Open No. 60-189519
However, as a result of various studies, the inventor has found that there is a point to be further improved. In the past, in particular, the constant control of the estimated terminal pressure was insufficient with respect to the setting of the maximum rotation speed and the water level in the case of a well.
[0006]
[Problems to be solved by the invention]
Accordingly, it is an object of the present invention to provide a variable speed water supply device capable of performing more accurate estimated terminal pressure control using a cascade pump.
[0007]
Another object of the present invention is to provide a variable-speed water supply device that can be properly controlled according to a change in the maximum rotation speed of the cascade pump or a change in the water level of the well.
[0008]
[Means for Solving the Problems]
According to the present invention, in a variable speed water supply device comprising a cascade pump, a pressure sensor provided on the discharge side of the cascade pump, a motor for driving the cascade pump, and a controller for controlling the rotation speed of the motor, The controller has a storage unit that stores the pump rotation speed and the pressure of the discharge pipe, calculates the maximum rotation speed, performs constant control of the estimated end pressure, and increases the maximum rotation speed when the maximum rotation speed further increases during use. It has a function to perform constant control of the estimated terminal pressure by the number.
[0009]
Further according to the present invention, in a variable speed water supply device comprising a cascade pump, a pressure sensor provided on the discharge side of the cascade pump, a motor for driving the cascade pump, and a controller for controlling the rotation speed of the motor, The controller includes a storage unit for storing the pump characteristics, and has a function of determining the operating pressure associated with the rise and fall of the water level on the suction side and performing constant control of the estimated end pressure.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 2 show a front view and a top view of an automatic water supply apparatus A having a cascade pump embodying the present invention. A cascade pump 2 driven by a motor 4 is installed on a unit base 1 having a piping function. The unit base 1 is covered with a unit cover 3. A suction pipe 5 and a discharge pipe 6 are fixed to the unit base 1 in the unit cover 3.
[0011]
With the rotation of the pump 2, the water passes through the suction pipe 5, and a check valve 7 for preventing backflow from the discharge side to the suction side when the pump is stopped, and a flow for detecting the amount of water for stopping the pump. It is sucked into the pump 2 via the switch 8. And the water discharged from the pump 2 flows into the pressure tank 9 provided on the discharge side. This pressure tank 9 is for storing water when the pump 2 is stopped. A pressure sensor 10 for detecting the pressure on the discharge side is provided on the discharge side of the pump 2, and a discharge pipe 6 is provided on the downstream side of the pressure sensor 10. It is guided to the discharge pipe 6 as described above. In the figure, reference numeral 11 denotes a controller for starting and stopping the pump.
[0012]
FIG. 3 is an explanatory diagram of a variable speed water supply device embodying the present invention. In FIG. 3, water W accumulates at a level L in a well 12 dug from the ground S. The automatic water supply device A is installed on the ground S near the well 12.
[0013]
As shown, the suction pipe 5 is provided with a check valve 7 and a flow switch 8. The discharge pipe 6 of the cascade pump 2 is provided with a pressure sensor 10 and a pressure tank 9. The signal from the pressure sensor 10 is sent to the control unit 11a of the controller 11, and a frequency command from the control unit 11a is sent to the inverter 11b to control the motor 4 as described later. In the figure, M indicates a storage unit, which will be described later.
[0014]
FIG. 4 is a diagram illustrating that the constant estimated end pressure control is more efficient and more energy saving than the constant discharge pressure control according to the present invention. The horizontal axis represents the water amount Q, and the vertical axis represents the consumption. The power L and the pressure H are shown on the upper side, and the rotation speed is shown as a parameter in the figure. In the figure, u represents a curve of 100%, v represents a curve of 90%, and w represents a curve of 80%. In the above figure, a horizontal straight line x indicates the case where the discharge is performed at the pressure H0 and the pressure is controlled to be constant, and a curve y indicates the characteristic when the estimated terminal pressure is controlled according to the present invention.
[0015]
Referring to the upper and lower diagrams of FIG. 4, in the case of the discharge pressure constant control, the intersections H0, H2, and H1 of the line x and the lines u, v, and w are the rotation speeds of 100%, 90%, and 80%, respectively. %, Water amounts Q0, Q2, and Q1 are shown. Similarly, in the case of constant estimated end pressure control, water amounts at intersections H0, H4, and H3 are Q0, Q4, and Q3. Points corresponding to the respective water amounts in the rotation speed curve in the lower diagram are L0, L2, and L1 in the constant discharge pressure control, and a line x connecting these points is a characteristic of power consumption L in the constant discharge pressure control. The line y connecting the points L0, L4, L3 is the characteristic of the estimated terminal pressure constant control.
As can be seen from the comparison between the line x and the line y, it is understood that the power consumption is low and the efficiency is low at all rotations other than 100%.
[0016]
In one embodiment, the storage unit M in FIG. 3 stores in advance the relationship between the rotation speed of the pump and the internal pressure of the pipe on the discharge side.
In addition, the relationship between a plurality of predetermined rotation speeds and the pressure in the water supply pipe in another embodiment is stored.
With such a storage unit, the estimated terminal pressure can be suitably obtained.
[0017]
According to still another embodiment, the storage unit stores the maximum rotation during the variable speed operation. In this way, when a normal rotation speed exceeding the maximum rotation speed is input to the control unit, the value of the maximum rotation speed is set so that the control target pressure for each rotation speed of the pump can be reset. More preferred.
[0018]
As will be understood from the description of FIG. 4, it is necessary to set the point of the water amount Q0, that is, the setting of the maximum number of rotations to be used. However, according to the present invention, it is possible to perform the estimated terminal pressure constant control without setting the maximum operating speed.
[0019]
In FIG. 5, the pressure H is shown on the vertical axis, and the water amount Q is shown on the horizontal axis. FIG. 6 shows a flowchart. Curves a, b, and c in FIG. 5 are characteristic curves of the cascade pump similarly to FIG. 4, and the rotation speed of the cascade pump is b larger than a and c is larger than b.
[0020]
The control mode will be described with reference to FIGS. If there is no data on the maximum number of rotations to be used, a reference pressure PA is set, and discharge pressure constant control is performed at the reference pressure (step S1). At that time, the cascade pump performs an operation indicated by a straight line d. Then, as the rotational speed of the cascade pump 2 increases, it is assumed that the maximum rotational speed has been reached at the point e (step S2). That is, the rotation speed of the curve a is the first maximum rotation speed. Therefore, the controller 11 sets the rotation speed at the point e as the maximum rotation speed, and performs constant control of the estimated terminal pressure (step S3). The operation of the cascade pump 2 at that time is as shown by a curve f.
[0021]
In the subsequent operation, when the motor is operated at a rotation speed larger than the first maximum rotation speed a, for example, the rotation speed b (step S4), the controller 11 estimates a point g on the subsequent maximum rotation speed b as a new maximum rotation speed. Terminal pressure constant control is performed (step S5). The characteristic of the cascade pump 2 at that time is as shown by a curve h.
[0022]
When the setting of the reference pressure PA is changed, it is sufficient to cancel the maximum operating speed and perform the above operation again.
Storing the map of the reference pressure and the maximum number of revolutions in this way is convenient for piping changes and the like.
[0023]
Further, when an appropriate maximum rotation speed cannot be obtained, it is preferable to set the pressure based on a predetermined temporary maximum rotation speed.
[0024]
Next, when the water level L in the well 12 changes, there is no problem in the constant discharge pressure control. However, in the constant control of the estimated end pressure, the performance curve of the cascade pump changes. Therefore, it is necessary to correct according to the water level. .
First, this point will be described with reference to FIG. FIG. 7 is substantially the same as FIG.
[0025]
In FIG. 7, the vertical axis represents the pressure H and the horizontal axis represents the water amount Q, and the line u is the performance curve of the cascade pump when the rotation speed is 100%, that is, when the rotation speed is the maximum (highest frequency). As described above, in the constant control of the estimated end pressure, as shown by the curve y, the discharge pressure of the cascade pump is controlled for each water amount so as to start at the pressure PB when the water amount is zero and to reach the pressure PA at the maximum water amount. Thus, the pressure PB is the pressure at the time of shutoff, and the operating frequency of the cascade pump at that time is indicated by a curve HzB. In terms of control, the operating frequency is set to this value HzB as the minimum operating frequency and controlled so as not to fall below this value.
[0026]
When the water level L of the well 12 rises, the suction pressure changes with the rise of the water level L. Therefore, as shown in FIG. 8, the performance curve of the cascade pump also changes from the curve u to the curve ua indicated by a broken line outside the curve u. Changes to At this time, the constant control of the estimated terminal pressure naturally changes as shown by the curve ya. However, when the control is performed by the curve ya, the portion where the amount of water is small from the intersection A of the curve HzB and the curve ya is operated by the curve portion yb along the curve of the minimum operating frequency HzB, so that the cutoff pressure becomes PBa, and the cutoff pressure PB Since it is higher, it must be operated at a frequency HzBa lower than the minimum operating frequency HzB.
[0027]
FIG. 9 shows an aspect of constant control of the estimated end pressure of the cascade pump when the water level L drops.
Contrary to the case of FIG. 8, in this case, the characteristic of the cascade pump is a curve Ub inside the curve U, and as a result, the estimated end pressure constant control changes as a curve yc. At this time, the operation frequency of the lowest pressure PB is higher than the lowest operation frequency HzB.
[0028]
The water level in the well can be detected by using a water level meter. If the characteristic curve of the pump is known, it can be calculated from the suction pressure and the discharge pressure using, for example, a map.
However, since the characteristic curve of the cascade pump is stored in the controller based on FIGS. 8 and 9, if this is used, the estimated end pressure due to the rise and fall of the water level in the well can be obtained without detecting the water level gauge or the suction pressure. Constant control can be performed.
[0029]
FIG. 10 shows a flowchart of correction based on a change in water level. First, it is determined whether or not a predetermined time has elapsed as a timing for performing the correction (step S11). As this step S11, any of timings such as a start time and a stop time can be used in addition to a predetermined time. Therefore, for example, when the timing is at the time of starting, “within a predetermined time” in each of the following steps is replaced with “at the time of starting”.
[0030]
Then, the controller 11 determines whether or not the pressure has decreased to PB when the lowest frequency HzB of FIG. 7 is reached within a predetermined time (step S12). If it has not decreased, that is, if it is NO, the state is as shown in FIG. 8, and it is determined that the water level is rising (step S13). In this case, as can be seen from FIG. 8, since the pressure is PBa at the current frequency of HzB, the pressure is corrected to be the pressure PB at the lowest frequency HzBa (step S14).
[0031]
This correction can appropriately grasp the rise degree of the well water level because the rise degree is unknown.
That is, temporarily reduce only to the frequency of the predetermined value, capture the discharge pressure at that time, lower the lowest frequency so that the pressure finally drops to PB, and when the PB reaches the new lowest frequency HzBa, Thereafter, correction is performed by the difference between the frequencies HzB and HzBa, and the estimated terminal pressure constant control is performed.
[0032]
When step S12 is YES, the controller 11 determines whether or not the pressure has decreased to the lowest frequency HzB when the pressure reaches PB within a predetermined time (step S15). In the case of YES, it is determined that there is no change in the water level, and no correction is performed.
[0033]
However, if step S15 is NO, it is determined that the water level has dropped (step S16), and since it is the pressure PB at the frequency HzBb at present, correction is made assuming that the water level has dropped by the difference between the frequencies HzB and HzBb (step S17).
[0034]
This correction is supposed to have been performed until the deadline, and the well water level is lowered by the difference between the lowest operating frequency HzBb within the predetermined time and the initial operating frequency, and the correction is performed, and the estimated end pressure constant control is performed. .
[0035]
【The invention's effect】
As described above, according to the present invention, the following excellent effects can be obtained.
(A) Even if there is no data of the maximum rotation speed, the maximum rotation speed can be set by the operation, and the correct estimated terminal pressure constant control can be performed.
(B) Since the cascade pump has less noise in large water volume operation than in small water volume operation, it can be operated with less noise.
(C) Even if there is a change in the water level on the suction side, correct constant control of the estimated end pressure can be performed.
[Brief description of the drawings]
FIG. 1 is a front view of a variable speed water supply device embodying the present invention.
FIG. 2 is a top view of FIG.
FIG. 3 is an explanatory view showing one embodiment of the present invention.
FIG. 4 is a diagram for explaining that power consumption is saved when constant estimated end pressure control is performed using a cascade pump.
FIG. 5 is a view for explaining that the estimated terminal pressure constant control is automatically performed without setting the maximum operating speed.
FIG. 6 is a flowchart for performing estimated terminal pressure constant control according to FIG. 5;
FIG. 7 is a basic diagram for explaining a change in the estimated terminal pressure constant control depending on the rise and fall of the water level on the suction side.
FIG. 8 is a diagram for explaining a change in estimated terminal pressure constant control due to a rise in water level.
FIG. 9 is a diagram for explaining a change in estimated terminal pressure constant control due to a decrease in water level.
FIG. 10 is a flowchart showing a manner of detecting a water level up and down before driving.
[Explanation of symbols]
2 Cascade pump 4 Motor 6 Discharge pipe 7 Check valve 8 Flow switch 9 Pressure tank 10 Pressure sensor 11 Controller 11a ..Control unit 11b ... Inverter 12 ... Well M ... Storage unit L ... Water level

Claims (2)

In a variable speed water supply device comprising a cascade pump, a pressure sensor provided on the discharge side of the cascade pump, a motor for driving the cascade pump, and a controller for controlling the number of rotations of the motor, the controller has a pump rotation speed and Equipped with a storage unit that stores the pressure of the discharge pipe, performs the estimated end pressure constant control by obtaining the maximum rotation speed, and when the maximum rotation speed further increases during use, the estimated end pressure is fixed by the increased maximum rotation speed A variable speed water supply device having a function of performing control. In a variable speed water supply device comprising a cascade pump, a pressure sensor provided on the discharge side of the cascade pump, a motor for driving the cascade pump, and a controller for controlling the rotation speed of the motor, the controller stores the pump characteristics. A variable-speed water supply device, comprising: a storage unit that performs a control to determine an operating pressure accompanying rise and fall of a water level on a suction side and perform constant control of an estimated end pressure.

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