JP2006299939A - Water supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water supply device having reliable high empty operation prevention function without spending surplus cost. <P>SOLUTION: The water supply device includes a pump 10, an inverter 14 variably controlling a drive motor of the pump 10. Also, the device is provided with a first empty operation detecting means 34, 36, 38, 40 detecting an empty operation condition from rotation speed and drive current value of the pump, and a second empty operation detection means 34, 42, 44, 46 detecting an empty operation condition of the pump from rotation speed of the pump and pressure in a delivery side and water quantity. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to, for example, a water supply apparatus used for pumping water from a well, and more particularly, to a water supply apparatus including a motor pump that is operated at a variable speed by a frequency converter such as an inverter.

  For example, as a drive source for a well pump, a motor whose rotation can be controlled by a frequency converter (inverter) is widely used to operate the pump at a variable speed. By using the inverter, it is possible to operate regardless of the power source, and by performing variable speed operation, various controls according to the water source and the situation on the demand side are possible.

  By the way, the water level of a water source such as a well is not necessarily constant, and fluctuates depending on conditions such as season and weather, or the amount of pumped water. If the operation is performed in a situation where the water level is low, not only is the energy wasted, but the operation does not have a lubrication function in the sliding part of the pump, so the corresponding part will overheat and the parts will be damaged. .

  In order to prevent such idling, there is a method of detecting the water level by installing a water level sensor in the water source and controlling the operation according to this. As the water level sensor, a water level electrode or a float is used. However, installing such a sensor in a deep well, for example, requires the sensor itself, a control circuit for the sensor, and costs for installation and maintenance.

  As another method, there has been proposed a method of controlling the operation by detecting the idling state from the relationship between the rotational speed of the pump and the current value. In the idling state, the flow rate is zero and the load on the pump is small, so that the current value corresponding to the rotational speed is also small compared to the normal operation. Therefore, if the current value is less than a certain threshold value, it can be determined that the vehicle is in the idling state.

  Since this method can be executed by using the control circuit of the inverter of the pump itself, that is, by incorporating a control program in the control chip, the cost is small. However, when the pump sliding portion is clogged with sand, the load may not be reduced due to friction, and the current value may not fall below the threshold value. In this way, if there is another abnormal situation, the reliability cannot be achieved.

JP 2002-195163 A

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a water supply apparatus having a highly reliable idling prevention function without incurring extra costs.

  In order to achieve the above object, the water supply apparatus according to claim 1 detects an idle operation state of a pump from a pump, an inverter for variable speed control of a drive motor of the pump, and a rotation speed and a drive current value of the pump. And a second idling operation detecting means for sensing the idling state of the pump from the number of rotations of the pump, the pressure on the discharge side, and the amount of water.

  According to the first aspect of the present invention, the first idling detection means detects the idling state of the pump based on the load of the pump driving motor, and the second idling detection means detects the pump discharge side. The idling state of the pump is detected based on the situation. In this way, by using two detection means based on different data in combination or in combination, it is possible to perform highly accurate or more reliable idling detection.

The water supply device according to claim 2 is characterized in that, in the invention according to claim 1, when at least one of the first and second idling detection means detects idling, the operation of the pump is stopped. Features.
According to the second aspect of the present invention, by using the two detection means in combination, since the other supplements and detects the situation of the idle operation that cannot be detected by only one of the detection means, the more reliable prevention of the idle operation is achieved. It can be performed.

The water supply device according to claim 3 is characterized in that, in the invention according to claim 2, after the idling operation is detected and the pump is stopped, the operation of the pump is resumed after a predetermined time elapses.
According to the third aspect of the present invention, when the idle operation is a temporary cause, the operation is automatically restored after the cause is canceled. Therefore, it is possible to save the trouble of restoration work and to efficiently operate the pump.

According to a fourth aspect of the present invention, there is provided the water supply device according to any one of the first to third aspects, wherein the second idling detection means has a pump rotation speed of a predetermined value or more, and the water amount and pressure. The pump is stopped when the state where each is equal to or less than a predetermined value continues for a predetermined time.
According to the fourth aspect of the invention, when the idling state is instantaneous, the pump is not stopped, so that the pump can be efficiently operated.

  According to the water supply device according to any one of claims 1 to 4, reliable idle operation detection can be performed at a low cost by using two different detection means using equipment normally used for pump control. A water supply device with high safety can be provided.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a water supply device that pumps water from a deep well and supplies it to consumers. The submersible pump 10 installed in the well, the discharge pipe 12 installed in the submersible pump 10, and the submersible pump 10 are supplied with power. And it has the control panel 14 which accommodates the apparatus for controlling this. The discharge pipe 12 is provided with a check valve 16, a flow switch 18, a pressure sensor 20, and a pressure tank 22, and these and the control panel 14 are accommodated in the ground unit 24. The submersible pump 10 includes a pump main body and a drive motor, and an alternating current with a frequency controlled from an inverter 26 installed in the control panel 14 is supplied to the drive motor via a cable 28. A predetermined gas is sealed in the pressure tank 22, and this pressure rises if the water supply device continues to operate when the consumer is not in use. The pressure sensor 20 detects this pressure and sends an output signal to a control device installed on the control panel 14.

  This water supply apparatus operates differently depending on the usage mode on the consumer side. As a first mode, when there is a water receiving tank on the consumer side, the ON-OFF operation is controlled by the water level. That is, it is turned on when the water level meter in the water receiving tank emits a low level signal, and turned off when it issues a high level signal. In this case, the rotation speed of the pump 10 is controlled so that the pressure in the pressure tank 22 becomes a value that enables pumping to the height of the water receiving tank. As a second mode, when there is no water receiving tank on the consumer side, for example, when water from the pump 10 is directly supplied from a household faucet, it is turned on and off by the value of the pressure sensor 20, for example. In this case, the rotation speed of the pump 10 is controlled so that the pressure in the pressure tank 22 can be stably supplied from each faucet.

  In any case, the rotation speed of the pump 10, that is, the output frequency of the inverter 26 is controlled so that the pressure on the discharge side of the pump 10 is within a predetermined range. That is, if the pressure is below the set range, the control device increases the output frequency of the inverter 26, and if the pressure is above the set range, the control device decreases the frequency. The lower limit of the pressure setting range is a head that can supply water to each water receiving tank or from a faucet. Usually, it is programmed to control the rotation speed with the intermediate value of the pressure range as a target. In the second mode, if the amount of water used is large, the pressure may not increase. However, in this case, if the maximum number of rotations determined from the motor rating etc. is reached, the number of rotations should not be increased further. The operation is continued at that speed.

  Next, means for preventing damage to the apparatus due to idling will be described with reference to FIG. This water supply apparatus has two idle operation detection means, and when any one of them detects the idle operation, the operation of the pump 10 is stopped. The first detection means detects the load of the pump 10 to determine the idling operation, detects the driving current of the pump 10, and when the value is equal to or less than a predetermined value that is smaller than the value during the shut-off operation. Is determined to be idling. In this embodiment, the first detection means is a function executed by the control device 30 such as a dedicated or general-purpose computer, and the following units are also virtually configured in a chip, a personal computer, or the like. The

  The first detection unit includes a reference current value storage unit 32 that determines that the operation state is the idle operation. The reference current value is set corresponding to the operating frequency as shown in FIG. This is set as follows. When a predetermined pressure is output at a certain operating frequency, the current value representing the load on the motor decreases as the flow rate decreases, and when the flow rate is zero, only the energy for maintaining the pressure and loading work due to friction is obtained. This is represented as the cutoff operating current value in FIG. In the case of idling, since the impeller runs idly in the absence of water, the current value further decreases, and this is represented as the idling current value in FIG. These values can be measured and stored as data. Here, if an appropriate value intermediate between these cut-off operation current values and idle operation current values is determined as the reference current value, it can be determined that the operation is idle if the measured current value is less than this value. Therefore, this is memorized.

  In this water supply apparatus, the rotational speed of the pump 10 is obtained from the operating frequency output from the inverter 26. The reason for installing an instrument for actually measuring the number of revolutions is because of high costs. Below a certain value (usually about fmax / 4), the difference between the cutoff operating current value and the idle operating current value becomes small. Therefore, in order to avoid malfunction, the reference current value is set to zero in a predetermined region where the frequency is close to zero. In such a range, the idling operation is not judged.

  The first detection means further includes a frequency detection unit 34 that detects the output frequency of the inverter 26, a current detection unit 36 that detects a current value supplied from the inverter 26 to the motor, and a frequency detected by the frequency detection unit 34. The reference current value acquisition unit 38 that acquires the reference current value corresponding to the reference current value from the reference current value storage unit 32 is compared with the detected current value and the acquired reference current value. And a first determination unit 40 that determines that the vehicle is driving.

  Next, the second detection means will be described. This is to determine whether or not the idling operation is performed based on the state on the discharge side of the pump 10. When the flow rate is small and / or the pressure is small with respect to the rotation speed of the pump 10, the idling operation is determined. In this embodiment, the second detection means includes a flow sensor 18 and a pressure sensor 20 installed in the discharge pipe 12, a flow rate detection unit 42 and a pressure detection unit 44 that receive these outputs, and the frequency detection described above. Unit 34, and a flow rate detection unit 42, a pressure detection unit 44, and a second determination unit 46 that determines whether or not the vehicle is idling based on output signals from the frequency detection unit 34. Since the flow sensor 18 only needs to be able to determine the magnitude of the actual flow rate with respect to the set flow rate, the flow sensor 18 may be a so-called flow switch 18 that turns on and off a specific flow rate value as well as a flow meter that measures a continuous value. In the case of a flow meter, the measured value is input to the detection unit, and in the case of the flow switch 18, an ON-OFF signal is input.

  A setting value for determining that the pump 10 is idling is input to the second determination unit 46 in advance. This is the set flow rate Qmin, the set pressure Hmin, and the set frequency f0. The set frequency f0 is set to the maximum rotation speed fmax of the pump 10 described above or a value close thereto. In the case of idling, since the discharge pressure does not increase, the control device 30 performs control so as to increase the output frequency of the inverter 26. Therefore, the measurement frequency also becomes the maximum rotation speed fmax of the pump 10 or a value close thereto. Because. The set flow rate Qmin is zero or a value close to this. The set pressure Hmin is set to an appropriate value smaller than the operation target pressure of the pump 10 described above. The second determination unit 46 determines that the idling operation is performed when the idling state continues for a predetermined time. This is because a temporary idling operation is unlikely to cause overheating or breakage of the sliding portion. Such a standby set time t0 is set in advance by the input means of the control device 30 or the like.

  Hereinafter, the operation of the water supply apparatus configured as described above will be described focusing on the idling prevention operation. In this example, it is the case of the first mode in which there is a water receiving tank on the consumer side, and the target set pressure is set to a sufficiently high value in order to supply water quickly. A case where the maximum rotational speed fmax is reached will be described. For example, it is installed in a deep well in a depopulated area such as a ranch and supplies drinking water for livestock to a receiving tank using a solar cell as a power source.

  FIG. 4 is a flowchart showing a control process for preventing idling, and the control device 30 detects the operating frequency of the pump 10 in step 1 and measures it based on the data stored in the reference current storage unit in step 2. A reference current value corresponding to the operated frequency is obtained. Next, in step 3, the current value of the drive motor is detected, and in step 4, it is determined whether measured current value ≦ reference current value. If YES, since the idling operation has been detected by the first detecting means, the operation of the pump 10 is stopped in step 11.

  If the determination in step 4 is NO, the determination by the second detection means is performed. In step 5, it is determined whether or not the flow rate on the discharge side is equal to or lower than the set flow rate. If YES, in step 6, it is determined whether or not the pressure detected by the pressure sensor 20 is equal to or lower than the set pressure. If “YES” in the step 6, it is further determined in a step 7 whether or not the obtained operation frequency is equal to or higher than a set frequency. If “YES” in the step 7, a timer in the control device 30 is started in a step 8, or if the timer has already been started, it is continued. In step 10, it is determined whether the elapsed time has reached the set time t 0. If YES, the pump 10 is stopped in step 11. If the elapsed time has not reached the set time t0 in step 10, the process returns to step 1 and the following steps are repeated. If any of the determinations in steps 5 to 7 is NO, the timer is canceled in step 9 and the process returns to step 1.

  Thus, in this water supply apparatus, since the 1st detection means and the 2nd detection means are used together, idle driving | operation can be prevented more reliably by compensating for a mutual fault. For example, the first detection means cannot detect idling when sand is clogged in the sliding portion of the pump 10, but the second detection means can detect if the flow rate is actually low. On the other hand, in the second detection means, when the discharge pressure constant control or the estimated terminal pressure constant control is performed, a certain time is required for the control from the occurrence of the idle operation state until the idle operation is detected and the pump 10 is stopped. Since the first detection means operates quickly, there is no problem.

  Note that the operation of the pump 10 may be automatically restarted after a predetermined time after the idle operation is detected and the pump 10 is stopped. This is particularly suitable in the case of unmanned operation in the depopulated area described above. This is because manual recovery takes time, and after a certain period of time, there is a possibility that the cause of the idling has been resolved, and even if the cause is not resolved, it can be stopped again.

It is a figure which shows embodiment which installed the water supply apparatus of this invention in the deep well. It is a block diagram which shows the structure of the control apparatus of the water supply apparatus of embodiment of FIG. It is a graph explaining the control method of a 1st detection means. It is a flowchart explaining the idle driving | running | working detection process of the water supply apparatus of embodiment of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Submersible pump 12 Discharge piping 14 Control panel 16 Check valve 18 Flow switch 20 Pressure sensor 22 Pressure tank 24 Ground unit 26 Inverter 28 Cable 30 Controller 32 Reference current value memory | storage part 34 Frequency detection part 36 Current detection part 38 Reference current Value acquisition unit 40 First determination unit 42 Flow rate detection unit 44 Pressure detection unit 46 Second determination unit

Claims (4)

  A pump, an inverter for variable speed control of the drive motor of the pump, a first idle operation detecting means for detecting an idle operation state of the pump from the rotational speed and driving current value of the pump, the rotational speed of the pump, and the discharge side A water supply apparatus comprising: a second idling operation detecting means for sensing an idling operation state of the pump from the pressure and the amount of water.   2. The water supply device according to claim 1, wherein when at least one of the first and second idling detection means detects idling, the operation of the pump is stopped.   The water supply device according to claim 2, wherein after the idle operation is detected and the pump is stopped, the operation of the pump is resumed after a predetermined time has elapsed. The second idling detection means is characterized in that the pump is stopped when a state in which the rotation speed of the pump is equal to or greater than a predetermined value and the amount of water and the pressure are each equal to or less than a predetermined value continues for a predetermined time. The water supply apparatus in any one of Claim 1 thru | or 3.

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