JP2017198222A - Water supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water supply device capable of achieving energy saving while inhibiting a pump start frequency from excessively increasing.SOLUTION: A water supply device includes a pump 2 for transferring water, a motor 3 for driving the pump 2, a frequency converter supplying electric power to the motor 3 and performing variable speed operation of the pump 2, a pressure tank 28 maintaining a delivery side pressure of the pump, and a control section 40 for controlling the operation of the pump so as to maintain a target pressure. The control section 40 performs small water amount stop operation in a normal mode or an energy saving mode in which small water amount stop operation time is shorter than in the normal mode.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a water supply apparatus that supplies water to a building such as an apartment house or an office building using a pump.

  A water supply device is installed in a building such as an apartment house or an office building and supplies water to each water supply end. FIG. 8 shows a typical example of such a water supply device. The water supply device includes two pumps 102 that pressurize and supply water, a motor 103 for driving each pump 102, and a motor 103. And an inverter (frequency converter) 120 for supplying electric power. The water supply device includes a pressure tank 128 and a discharge-side pressure sensor 126 on the discharge side of the pump 102, and a flow switch (flow rate detection means) 124 and a check valve 122 for each pump 102. The pressure tank 128, the discharge side pressure sensor 126, the flow switch 124, and the check valve 122 are provided in a discharge pipe 132 connected to the discharge port of the pump 102.

  A suction pipe 105 connected to the suction port of the pump 102 is connected to the water pipe 4. The suction pipe 105 is provided with a suction side pressure sensor 121 and a backflow prevention device 125. Further, a bypass pipe 108 for supplying water only by the pressure of the water pipe 4 is provided between the suction pipe 105 and the discharge pipe 132. A check valve 123 is provided in the middle of the bypass pipe 108. The control unit 140 that controls the pump 102 performs the rotational speed control and the number control of the pumps 102 according to the situation based on the signals from these sensors.

  In such a water supply device, when the amount of water used at the water supply end is small, in order to prevent heating due to the shut-off operation of the pump 102 and to reduce wasteful operation time (energy saving), a small amount of water described below Stop operation is performed. First, when the flow switch 124 detects a small amount of water, the flow switch 124 generates a flow rate reduction signal. Then, it is confirmed that the low water amount state continues for a predetermined time. The time and operation for confirming that the low water amount state is continued are referred to as a state watching time and a state watching operation, respectively. When the state watching operation is completed, the pump 102 is controlled to accumulate pressure in the pressure tank 128 and then stop. The operation until the pump 102 stops after the flow switch 124 detects the small water amount is the small water amount stop operation.

  When water is used at the water supply end while the pump 102 is stopped, first, water is supplied from the pressure tank 128 to each water supply end. When the pressure in the pressure tank 128 drops to a predetermined starting pressure value, the pump 102 is started again. The pump 102 performs a variable speed operation so that the water pressure at the water supply end is maintained at a predetermined pressure, and after that, when the amount of water used at the water supply end decreases, the pump 102 performs a low water amount stop operation again.

  The purpose of the operation for stopping the small amount of water is to prevent overheating of the motor 103 due to the shut-off operation of the pump 102 and to reduce useless operation time. When the accumulated pressure during the operation for stopping the small amount of water is too high, the rapid pressure increase due to the accumulated pressure before the pump 102 is stopped is frequently repeated, which causes a problem in the mechanical life of the water supply device. Furthermore, frequent pressure fluctuations occur at each water supply end, causing a problem that usability as a water supply device is deteriorated. If the pressure increase value due to the pressure accumulation during the stoppage of a small amount of water is kept low, a sudden pressure increase at each water supply end is eliminated, and the usability as a water supply device is improved. However, since the pressure increase value due to accumulated pressure is low, the time from when the pump 102 is stopped until the pump 102 is restarted is shortened, and the frequency of starting and stopping the pump 102 is increased.

  In order to solve such a problem, Patent Literature 1 and Patent Literature 2 disclose a configuration in which a fuzzy inference function is applied to a small water amount stop operation. According to this configuration, while achieving the purpose of the original low water volume stop function of preventing the heating due to the pump shut-off operation and reducing wasteful operation time, the pump start / stop frequency is reduced and the rapid pressure accumulation due to the pressure accumulation before the low water volume stop is achieved. The conflicting objectives of reducing the pressure increase can be achieved with a certain degree of balance.

  However, the water supply pattern at each water supply end is various and diverse as well as the lifestyle of people, and the small water stop operation based on the fuzzy reasoning function is not universal. In particular, a small amount of water may be intermittently supplied at night in a residence with a large number of units. In such a case, the water supply device should know when the pump is started after the small amount of water is once supplied and the pump is started, and then the pump is stopped by performing the low water amount stop operation. Absent. For example, there may be a time zone in which a small amount of water that is less than one minute is intermittently provided every few minutes, or there may be no water supply for one hour or more.

  In recent years, energy saving has become a social need. However, the small water amount stop operation based on the conventional fuzzy reasoning function is to increase the state-of-seeing operation time when the previous operation time is short. When the amount of water supply is relatively low, such as at night, the previous operation time is often shortened, and when the low water volume stop operation based on the conventional fuzzy reasoning function is performed at night, the pump may be wasted. Yes, there may be inconsistencies from the viewpoint of energy saving. As described above, too much consideration of the suppression of the start-up frequency is performed, and energy consumption is wasted if the state watching operation is performed for a predetermined time after the demand for water supply is reduced.

JP-A-7-71060 JP-A-9-96278

  The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide a water supply apparatus capable of achieving energy saving while suppressing an excessive pump start frequency.

  In order to achieve the above-described object, one aspect of the present invention includes a pump that transfers water, a motor that drives the pump, a frequency converter that supplies electric power to the motor, and operates the pump at a variable speed. A pressure tank that holds the discharge side pressure of the pump, and a control unit that controls the operation of the pump so as to maintain a target pressure, and the control unit performs a low water volume stop operation in a normal mode or the normal mode. The water supply device is configured to be executed in any one of the energy saving modes in which the time of the small water amount stop operation is shorter than that in the mode.

In a preferred aspect of the present invention, the control unit performs the small water volume stop operation in either the normal mode or the energy saving mode based on the latest operation history of the pump.
In a preferred aspect of the present invention, the small water amount stop operation includes a state watching operation in which a state where the amount of water used is low, and the time for the state watching operation in the energy saving mode is shorter than that in the normal mode. It is characterized by.
In a preferred aspect of the present invention, the control unit controls the operation of the pump according to a target pressure control curve.
In a preferred aspect of the present invention, the control unit includes, as the target pressure control curve, a first target pressure control curve and a second target pressure control curve whose target pressure is lower than the first target pressure control curve. Either one of them is selected, and based on the latest operation history, the small water amount stop operation is executed in the normal mode and the first target pressure control curve is selected, or A small water amount stop operation is executed in the energy saving mode, and the second target pressure control curve is selected and operated.
A preferable aspect of the present invention further includes an eco-operation button for switching to the normal mode or the energy-saving mode, and when the eco-operation button is pressed, the control unit operates the pump immediately before the small water amount stop operation. The small water volume stop operation is executed in an energy saving mode in which the state watching operation is not performed regardless of time.

  One reference example of the present invention includes a pump that transfers water, a motor that drives the pump, a frequency converter that supplies electric power to the motor and operates the pump at a variable speed, and a discharge-side pressure of the pump. A pressure tank to hold, and a control unit that controls the operation of the pump according to a target pressure control curve, the control unit to check that the state where the amount of water used is low continues, The accumulator operation for accumulating pressure in the pressure tank by increasing the speed of the pump and the small water volume stop operation including stopping the pump are performed in either the normal mode or the energy saving mode, and the control unit When the operation time of the pump immediately before the water amount stop operation exceeds the first threshold value, the small water amount stop operation is executed in the normal mode, and the operation time is less than the first threshold value. When the previous stop time of the pump exceeds the second threshold value, the small water amount stop operation is executed in the energy saving mode, and the time for the state watching operation in the energy saving mode is The water supply device is characterized in that it is 0 or more and is shorter than the time of the state watching operation in the normal mode.

In a preferred aspect of the reference example, the control unit is configured such that the operation time of the pump immediately before the small water amount stop operation is equal to or less than a first threshold value, and the previous stop time of the pump is a second value. If it is less than or equal to the threshold value, the small water volume stop operation maintains the currently selected mode.
In a preferred aspect of the above reference example, the small water volume stop operation further includes a pressure holding operation for holding the discharge side pressure after accumulating in the pressure tank, and the time of the pressure holding operation in the energy saving mode is 0 or more. And the time is shorter than the time of the pressure holding operation in the normal mode.
In a preferred aspect of the above reference example, when the small water amount stop operation is executed in the energy saving mode, when the total of the operation time and the stop time is shorter than a predetermined reference time, the control unit The operation of the pump is continued until the sum of the operation time and the stop time reaches the predetermined reference time.

In a preferred aspect of the above reference example, the control unit uses the first target pressure control curve as the target pressure control curve, and a second target pressure control curve whose target pressure is lower than the first target pressure control curve. When the operation time of the pump immediately before the small water amount stop operation exceeds a first threshold value, the small water amount stop operation is selected. In the normal mode, the first target pressure control curve is selected, the operation time is equal to or less than a first threshold value, and the previous stop time of the pump is a second threshold value. In the case where the amount of water is exceeded, the small water amount stop operation is executed in the energy saving mode and the second target pressure control curve is selected.
A preferred embodiment of the above reference example is a case where the operation time of the pump exceeds the first threshold value, and the stop time of the pump immediately before the pump is started is set to the second threshold value. If it exceeds, the second target pressure control curve is selected as the target pressure control curve.
In a preferred aspect of the above reference example, in the pressure accumulation operation, the discharge side pressure is gradually increased from a current value to a predetermined stop pressure value in a stepwise manner.

  One reference example of the present invention includes a pump that transfers water, a motor that drives the pump, a frequency converter that supplies electric power to the motor and operates the pump at a variable speed, and a discharge-side pressure of the pump. A pressure tank to hold, and a control unit that controls the operation of the pump according to a target pressure control curve, the control unit to check that the state where the amount of water used is low continues, A pressure accumulation operation for accumulating pressure in the pressure tank by accelerating the pump and a small water volume stop operation including stopping the pump are performed, and the control unit is configured to perform a first target as the target pressure control curve. A pressure control curve, and a second target pressure control curve having a lower target pressure than the first target pressure control curve. When the operation time of the pump immediately before the low water volume stop operation is equal to or less than the first threshold value and the previous stop time of the pump exceeds the second threshold value, The water supply device is characterized in that the small water amount stop operation is executed in an energy saving mode in which no driving operation is performed, and the second target pressure control curve is selected.

In a preferred aspect of the reference example, the control unit is configured such that the operation time of the pump immediately before the small water amount stop operation is equal to or less than a first threshold value, and the previous stop time of the pump is a second value. When the target pressure control curve is equal to or less than a threshold value, the target pressure control curve maintains the currently selected target pressure control curve, and the small water amount stop operation maintains the same low water amount stop operation as the previous time. To do.
A preferred aspect of the above reference example, the small water amount stop operation further includes a pressure holding operation for holding the discharge side pressure after accumulating in the pressure tank, and when the small water amount stop operation is executed in the energy saving mode, The state watching operation and the pressure holding operation are not performed.
In a preferred aspect of the above reference example, when the small water amount stop operation is executed in the energy saving mode, when the total of the pump operation time and the stop time is shorter than a predetermined reference time, the control unit The operation of the pump is continued until the sum of the operation time and the stop time reaches the predetermined reference time.
In a preferred aspect of the above reference example, in the pressure accumulation operation, the discharge side pressure is gradually increased from a current value to a predetermined stop pressure value in a stepwise manner.

  One reference example of the present invention includes a pump that transfers water, a motor that drives the pump, a frequency converter that supplies electric power to the motor and operates the pump at a variable speed, and a discharge-side pressure of the pump. A pressure tank to hold, and a control unit that controls the operation of the pump according to a target pressure control curve, the control unit includes an eco-operation button, and the control unit continues to be in a state where the amount of water used is low. The operation is configured to perform a low-volume stop operation including a state-of-the-art operation, a pressure accumulating operation for accumulating pressure in the pressure tank by increasing the speed of the pump, and a stop of the pump. As the target pressure control curve, one of a first target pressure control curve and a second target pressure control curve having a target pressure lower than that of the first target pressure control curve is selected. When the eco-operation button is pressed, the control unit stops the small water amount in the energy saving mode in which the state watching operation is not performed regardless of the operation time of the pump immediately before the small water amount stop operation. The control unit executes an operation, and the operation time of the pump immediately before the small water amount stop operation is equal to or less than a first threshold value, and the previous stop time of the pump is a second threshold value. When the pressure exceeds the second target pressure control curve, the water supply device is characterized in that the second target pressure control curve is selected.

In a preferred aspect of the reference example, the control unit is configured such that the operation time of the pump immediately before the small water amount stop operation is equal to or less than a first threshold value, and the previous stop time of the pump is a second value. When the target pressure control curve is equal to or lower than the threshold value, the target pressure control curve maintains the currently selected target pressure control curve.
A preferred aspect of the above reference example, the small water amount stop operation further includes a pressure holding operation for holding the discharge side pressure after accumulating in the pressure tank, and when the small water amount stop operation is executed in the energy saving mode, The state watching operation and the pressure holding operation are not performed.
In a preferred aspect of the above reference example, when the small water amount stop operation is executed in the energy saving mode, when the total of the pump operation time and the stop time is shorter than a predetermined reference time, the control unit The operation of the pump is continued until the sum of the operation time and the stop time reaches the predetermined reference time.
In a preferred aspect of the above reference example, in the pressure accumulation operation, the discharge side pressure is gradually increased from a current value to a predetermined stop pressure value in a stepwise manner.

  According to the present invention, based on the latest operation history (operation status) of the pump, the small water amount stop operation is executed in either the normal mode or the energy saving mode. That is, when the amount of water used is large, the small water amount stop operation is performed in the normal mode, and when the amount of water used is small, the small water amount stop operation is performed in the energy saving mode. Therefore, energy saving can be realized while suppressing an excessive pump start frequency without causing the user to feel inconvenience.

Drawing 1 is a mimetic diagram showing one embodiment of a water supply apparatus. FIG. 2 is an operational characteristic diagram of the pump for explaining an example of the estimated terminal pressure constant control. FIG. 3 is a graph showing the operation state of the pump. FIG. 4 is a graph showing a small water amount stop operation in the energy saving mode. FIG. 5 is a graph showing a small water amount stop operation in the energy saving mode when the time of the state watching operation and the pressure holding operation is zero. FIG. 6 is an operation characteristic diagram of a water supply apparatus having a first target pressure control curve and a second target pressure control curve. FIG. 7 is a graph showing the pressure accumulation operation. FIG. 8 is a schematic view showing a conventional water supply device.

  Embodiments of the present invention will be described below with reference to the drawings. Drawing 1 is a mimetic diagram showing one embodiment of a water supply apparatus. As shown in FIG. 1, the suction port of the water supply apparatus 1 is connected to the water pipe 4 or the water receiving tank which is not shown in figure. A water supply pipe 7 is connected to the discharge port of the water supply apparatus 1, and the water supply pipe 7 communicates with a water supply end (for example, a faucet) on each floor of the building. The water supply apparatus 1 increases the pressure of the water from the water pipe 4 or the water receiving tank and supplies the water to each water supply end of the building.

  A directly connected water supply device 1 in which a pump is directly connected to a water pipe 4 includes a pump 2, a motor 3 as a drive device that drives the pump 2, and an inverter 20 as a frequency converter that drives the motor 3 at a variable speed. , A backflow prevention device 25 arranged on the suction side of the pump 2, a pressure sensor 21 arranged on the suction side of the backflow prevention device 25, a check valve 22 arranged on the discharge side of the pump 2, and a check valve 22 is provided with a pressure sensor 26, a flow switch 24, and a pressure tank 28 arranged on the discharge side. These components are accommodated in the cabinet 30 of the water supply apparatus 1. There is also a type of water supply device that does not include the cabinet 30.

  A suction pipe 5 is connected to the suction port of the pump 2, and a discharge pipe 32 is connected to the discharge port of the pump 2. The bypass pipe 8 for supplying water only with the pressure of the water pipe 4 is provided between the suction pipe 5 and the discharge pipe 32, and the check pipe 23 is provided in the bypass pipe 8. In the present embodiment, two sets of the pump 2, the motor 3, the check valve 22, and the flow switch 24 are provided, and these are provided in parallel. One set or three or more sets of pumps, motors, check valves, and flow switches may be provided. In the direct connection type water supply apparatus, the pump 2 is connected to the water pipe 4 via the suction pipe 5 as shown in FIG. 1. In the water tank type water supply apparatus, the pump 2 is connected to the water reception tank via the suction pipe 5. Connected to. In the case of this water tank type water supply device, the backflow prevention device 25, the suction side pressure sensor 21 and the bypass pipe 8 shown in FIG. 1 are not provided.

  The check valve 22 is provided in the discharge pipe 32 and prevents a back flow of water when the pump 2 is stopped. The flow switch 24 is a flow rate detector that detects that the flow rate of water flowing through the discharge pipe 32 has decreased to a predetermined value. The pressure sensor 26 is a water pressure measuring device for measuring the discharge side pressure (that is, the back pressure applied to the water supply apparatus 1). The pressure tank 28 is a pressure retainer for retaining the discharge side pressure while the pump 2 is stopped.

  The water supply apparatus 1 includes a control unit 40 that controls the operation of the pump 2. The inverter 20, the flow switch 24, the pressure sensor 21, and the pressure sensor 26 are connected to the control unit 40 via signal lines. When the water supply device 1 is in a water supply operation in which water is used, the water supply device 1 is operated so as to maintain the target pressure of the discharge side pressure. When the flow switch 24 detects that the water flow rate has decreased to a predetermined value, the control unit 40 issues a command to the inverter 20 to temporarily increase the rotational speed of the pump 2 and accumulates pressure in the pressure tank 28. After that, the operation of the pump 2 is stopped. When the discharge side pressure (water pressure in the discharge pipe 32) decreases to a predetermined starting pressure value, the control unit 40 issues a command to the inverter 20 to start the operation of the pump 2. The control unit 40 stores in advance a starting pressure value that serves as a trigger for starting the pump 2.

  When water is used in the building with the pump 2 stopped, the discharge-side pressure of the pump 2 decreases. When the discharge side pressure, that is, the output value of the pressure sensor 26 falls to the predetermined starting pressure value, the control unit 40 starts the pump 2. During operation of the pump 2, pressure control such as estimated terminal pressure constant control and discharge-side pressure constant control is performed based on the output value of the pressure sensor 26.

  When the use of water in the building is stopped, the flow rate of water discharged from the pump 2 decreases. When detecting that the flow rate of water from the pump 2 has decreased to a predetermined value, the flow switch 24 sends a flow rate decrease signal to the control unit 40. The control unit 40 receives this flow rate reduction signal, issues a command to the inverter 20, increases the rotational speed of the pump 2 until the discharge side pressure reaches a predetermined stop pressure, and then stops the pump 2. Such a pump stop operation is called a small water amount stop operation.

  In the estimated terminal pressure constant control, the water pressure at the water supply end (such as a faucet) is controlled to be constant by appropriately changing the target pressure according to the resistance loss in the water supply pipe in the building. FIG. 2 is an operational characteristic diagram of the pump for explaining an example of the estimated terminal pressure constant control. In FIG. 2, the horizontal axis represents the flow rate of water, and the vertical axis represents the discharge side pressure, that is, the head (head).

PA shown in FIG. 2 is the discharge-side pressure of the pump 2 at the maximum flow rate, and PB is the discharge-side pressure of the pump 2 during the shut-off operation of the pump 2 (that is, when the flow rate is 0). The curve indicated by the symbol N _MAX is a performance curve of the pump 2 when the pump 2 is operated at the rotational speed N _MAX that achieves the pressure PA, and the curve indicated by the symbol N _MIN is the rotational speed that achieves the pressure PB. (Cutoff speed) A performance curve of the pump 2 when the pump 2 is operated at N _MIN .

  The target pressure control curve R is a curve determined on the basis of the sum of pipe loss depending on the maximum head of the building, the pressure required to use the water supply end (such as a faucet), and the flow rate. This target pressure control curve R is a curve used for performing the estimated terminal pressure constant control, and is generally a quadratic curve. The target pressure control curve R represents the relationship between the discharge flow rate of the pump 2 and the target pressure of the pump 2. The pump 2 is operated at an operating point that is an intersection of the performance curve N and the target pressure control curve R.

  In the estimated terminal pressure constant control, the rotational speed of the pump 2 is controlled in consideration of the pipe resistance (indicated by the target pressure control curve R) corresponding to the flow rate of water. That is, the rotational speed of the pump 2 is controlled based on the output value of the pressure sensor 26 so that the discharge side pressure of the pump 2 changes along the target pressure control curve R. When the flow rate is small, the pipe resistance is small, and accordingly, the required power of the pump 2 is reduced, and energy saving operation is realized.

During operation of the pump 2, the discharge side pressure of the pump 2 is controlled between PA and PB. Therefore, during steady operation, the pump 2 is driven at a rotational speed of N _MIN or higher. In FIG. 2, when the pressure PB is set so that the pressure PB becomes equal to the pressure PA, the control unit 40 executes discharge pressure constant control. In this case, the control unit 40 controls the rotation speed of the pump 2 so that the discharge side pressure of the pump 2 maintains PA (= PB).

  FIG. 3 is a graph showing the operating state of the pump 2. In FIG. 3, the vertical axis represents the rotational speed of the pump 2, and the horizontal axis represents time. When the discharge side pressure of the pump 2 decreases and reaches a predetermined starting pressure value, the control unit 40 starts the pump 2 (time T1). The controller 40 controls the rotational speed of the pump 2 based on the output value of the pressure sensor 26 so that the discharge side pressure of the pump 2 changes along the target pressure control curve R. When the use of water at the water supply end decreases and the flow rate of water reaches a predetermined value, the flow switch 24 transmits a flow rate decrease signal to the control unit 40 (T2). From time T1 to time T2, the water supply device 1 (pump 2) is operated to perform the water supply operation. Even when the control unit 40 receives the flow rate reduction signal, the controller 40 does not immediately perform the pressure accumulation operation, but performs the mode watching operation for a predetermined time (from T2 to T3). This state operation is an operation for confirming that the state where the amount of water used is low continues, in order to avoid frequent stop and start of the pump 2, and the accuracy of detecting the flow rate drop of the flow switch 24. Done to increase.

  If the discharge-side pressure is kept substantially constant during this state operation, the control unit 40 temporarily increases the target pressure of the pump 2 and accumulates it in the pressure tank 28 (from T3 to T4). Then, a pressure holding operation is performed to keep the target pressure of the pump 2 constant for a predetermined time (from T4 to T5), and then the pump 2 is stopped (T5). As described above, the operation for stopping the small amount of water is the operation for monitoring the discharge side pressure, the pressure accumulation operation for increasing the speed of the pump 2 to accumulate pressure in the pressure tank 28, and the target pressure of the pump 2 being constant after accumulating pressure in the pressure tank 28. And holding the discharge side pressure and stopping the pump 2.

  However, it takes a certain amount of time to perform such a small water amount stop operation, which is not preferable from the viewpoint of energy saving. In particular, when there is little demand for water supply such as at night, it is not preferable to perform a small amount of water stop operation over a long time.

  Therefore, the control unit 40 is configured to automatically switch the small water volume stop operation between the normal mode and the energy saving mode based on the latest operation history (operation status) of the pump 2. As shown in FIG. 1, the control unit 40 is provided with an eco-operation button 41. The eco operation button 41 is a switch for switching the operation of the water supply apparatus 1 between a normal operation and an energy saving operation. In normal operation, the small water volume stop operation is always executed in the normal mode. In the energy saving operation, as described above, based on the latest operation history (operation status) of the pump 2, the small water amount stop operation is executed in either the normal mode or the energy saving mode. When the eco operation button 41 is pressed, the operation of the water supply apparatus 1 is switched from the normal operation to the energy saving operation, and when the eco operation button 41 is pressed again, the operation of the water supply apparatus 1 is switched from the energy saving operation to the normal operation.

  The small water amount stop operation described with reference to FIG. 3 is a small water amount stop operation in the normal mode. FIG. 4 is a graph showing a small water amount stop operation in the energy saving mode. When the discharge side pressure of the pump 2 decreases and reaches a predetermined starting pressure value, the control unit 40 starts the pump 2 (time T1). The controller 40 controls the rotational speed of the pump 2 based on the output value of the pressure sensor 26 so that the discharge side pressure of the pump 2 changes along the target pressure control curve R. When the use of water at the water supply end decreases and the flow rate of water reaches a predetermined value, the flow switch 24 transmits a flow rate decrease signal to the control unit 40 (T2). The control unit 40 performs the state watching operation in a shorter time than the state watching operation in the normal mode shown in FIG. 3 (from T2 to T3 '). The controller 40 temporarily increases the rotational speed of the pump 2 to accumulate pressure in the pressure tank 28 (from T3 ′ to T4 ′), and performs the pressure holding operation for a shorter time than the pressure holding operation in the normal mode. (T4 ′ to T5 ′), and then the operation of the pump 2 is stopped (T5 ′).

  As can be seen from the comparison between the graph of FIG. 3 and the graph of FIG. 4, the time for the small water amount stop operation in the energy saving mode is shorter than the time for the small water amount stop operation in the normal mode. Therefore, energy saving can be realized by executing the operation for stopping the small amount of water in the energy saving mode.

  The normal mode and the energy saving mode of the small water stop operation can be switched as follows. When the operation time t1 (see FIGS. 3 and 4) of the pump 2 immediately before the small water amount stop operation exceeds a predetermined first threshold value, the control unit 40 performs the small water amount stop operation in the normal mode. Run. When the operation time t1 is less than or equal to the first threshold and the previous stop time t2 of the pump 2 (see FIGS. 3 and 4) exceeds a predetermined second threshold The control unit 40 executes the small water amount stop operation in the energy saving mode. When the operation time t1 is equal to or less than the first threshold value and the previous stop time t2 of the pump 2 is equal to or less than the predetermined second threshold value, the currently selected mode ( Normal mode or energy saving mode) is maintained as it is. That is, the same low water content stop operation as the previous time is performed. In this way, since the low water volume stop operation is switched between the normal mode and the energy saving mode based on the latest operation history (operation status) of the pump 2, the user can feel the inconvenience of the pump 2 without inconvenience. Energy saving can be achieved while suppressing an excessive start frequency.

  The state watching operation time in the energy saving mode is set to 0 or more and shorter than the state watching operation time in the normal mode. Furthermore, the pressure holding operation time in the energy saving mode may be shorter than the pressure holding operation time in the normal mode. In this case, the time of the pressure holding operation in the energy saving mode may be zero. FIG. 5 is a graph showing a small water amount stop operation in the energy saving mode when the time of the state watching operation and the pressure holding operation is zero. As can be seen from FIG. 5, the time of the state watching operation and the pressure holding operation being zero means that the state watching operation and the pressure holding operation are not performed. In this case, further energy saving can be realized as compared with the operation of stopping the small amount of water in the energy saving mode shown in FIG.

  In order to further improve energy saving, the target pressure control curve is changed from the first target pressure control curve R1 and the first target pressure control curve R1 simultaneously with switching between the normal mode and the energy saving mode of the small water amount stop operation. It is preferable to switch between the second target pressure control curve R2 having a low target pressure. FIG. 6 is an operation characteristic diagram of the water supply apparatus 1 including the first target pressure control curve R1 and the second target pressure control curve R2 as the target pressure control curve R described above. The first target pressure control curve R1 is the same as the target pressure control curve R described above. The first target pressure control curve R1 and the second target pressure control curve R2 are stored in the control unit 40.

  The control unit 40 switches the low water amount stop operation between the normal mode and the energy saving mode based on the latest operation history (operation status) of the pump 2 and at the same time, the first target pressure control curve R1 and the second target pressure control curve R1. One of the target pressure control curves R2 is selected. Specifically, when the operation time t1 of the pump 2 immediately before the small water amount stop operation exceeds the first threshold value, the control unit 40 executes the small water amount stop operation in the normal mode, The first target pressure control curve R1 is selected. In this case, after the pump 2 is started, the control unit 40 controls the rotational speed of the pump 2 based on the first target pressure control curve R1. When the operation time t1 is equal to or less than the first threshold value and the previous stop time t2 of the pump 2 exceeds the second threshold value, the control unit 40 saves the small water amount stop operation. While executing in the mode, the second target pressure control curve R2 is selected. Further, after the second target pressure control curve R2 is selected and the pump 2 is started, when the operation time t1 of the pump 2 exceeds the first threshold value, the control unit 40 During operation, the operation of the pump 2 is continued by switching to (selecting) the first target pressure control curve R1. Further, even when the previous operation time t1 of the pump 2 exceeds the first threshold value, the stop time t2 immediately before the pump 2 starts exceeds the second threshold value. The control unit 40 selects the second target pressure control curve R2. In this case, after the pump 2 is started, the control unit 40 controls the rotational speed of the pump 2 based on the second target pressure control curve R2.

  As another aspect, when the eco-operation button 41 is pressed, the control unit 40 can realize energy saving by executing a small water amount stop operation in the energy saving mode. That is, when the eco-operation button 41 is pressed, the control unit 40 executes the small water amount stop operation in the energy saving mode, and at the same time, based on the latest operation history (operation status) of the pump 2, the first target pressure control curve R1. And the second target pressure control curve R2 can be selected. Specifically, when the eco operation button 41 is pressed, the control unit 40 executes the small water amount stop operation in the energy saving mode regardless of the operation time t1 of the pump 2 immediately before the small water amount stop operation. Thereafter, the control unit 40 selects the first target pressure control curve R1 when the operation time t1 of the pump 2 immediately before the small water volume stop operation exceeds the first threshold value, and the pump 2 After starting, the rotational speed of the pump 2 is controlled based on the first target pressure control curve R1. When the previous stop time t2 of the pump 2 exceeds the second threshold value, the control unit 40 executes the small water amount stop operation in the energy saving mode and selects the second target pressure control curve R2. To do. In this case, after the pump 2 is started, the control unit 40 controls the rotational speed of the pump 2 based on the second target pressure control curve R2. Further, after the second target pressure control curve R2 is selected and the pump 2 is started, when the operation time t1 of the pump 2 exceeds the first threshold value, the control unit 40 During operation, the operation of the pump 2 is continued by switching to (selecting) the first target pressure control curve R1. Further, when the operation time t1 is equal to or less than the first threshold value and the previous stop time t2 of the pump 2 is equal to or less than the predetermined second threshold value, the currently selected time is selected. The target pressure control curve (that is, the first target pressure control curve R1 or the second target pressure control curve R2) is maintained as it is.

  The target pressure of the second target pressure control curve R2 is set lower than the target pressure of the first target pressure control curve R1. Therefore, energy saving can be realized by using the second target pressure control curve R2 in the water supply operation. In this way, by combining the energy saving mode of the small water amount stop operation and the second target pressure control curve R2, it is possible to realize the energy saving operation that cannot be achieved by the conventional water supply device.

  In the small water amount stop operation in the energy saving mode, as shown in FIGS. 4 and 5, the state watching operation is performed in a short time or the state watching operation is not performed. In this case, energy saving is realized, but on the other hand, the frequency of starting and stopping the pump 2 may increase. Therefore, in order to reduce the frequency of starting and stopping the pump 2, when the sum of the operation time t1 and the stop time t2 is shorter than the predetermined reference time ST (t1 + t2 <ST), the control unit 40 determines the operation time. The operation of the pump 2 may be continued until the sum of t1 and the stop time t2 reaches a predetermined reference time ST. In this case, the time for which the operation of the pump 2 is continued (that is, ST− (t1 + t2)) is an additional operation time, and the small water amount stop operation is executed in the energy saving mode after the additional operation time elapses. . On the other hand, when the sum of the operation time t1 and the stop time t2 is equal to or longer than the predetermined reference time ST (t1 + t2 ≧ ST), the control unit 40 immediately executes the low water amount stop operation in the energy saving mode. The predetermined reference time ST is, for example, 60 seconds. By executing such an operation, it is possible to balance energy saving and reduction in the frequency of starting and stopping the pump 2.

  In the pressure accumulation operation shown in FIGS. 3 to 5, if the discharge side pressure suddenly increases, the pressure tank 28 and the piping system may be damaged. For this reason, in the pressure accumulation operation, it is preferable to gradually increase the discharge side pressure stepwise from the current value to a predetermined stop pressure value. For example, as shown in FIG. 7, the control unit 40 increases the target pressure of the pump 2 stepwise over a predetermined pressure accumulation time t3, and the discharge side pressure is increased from the current value P1 to a predetermined stop pressure value P2. Increase gradually in steps. More specifically, the control unit 40 calculates a pressure increment dP to be increased per unit time dt by dividing a value ΔP obtained by subtracting the current value P1 from the stop pressure value P2 by a predetermined pressure accumulation time t3. The discharge side pressure is increased by the pressure increment dP every unit time dt.

  In another example, the pressure increment dP to be increased per unit time dt is set in advance, and the discharge side pressure is increased by the pressure increment dP every unit time dt until the discharge side pressure reaches the stop pressure value P2. Also good. In still another example, the next target pressure increment dP is determined every unit time dt, and the next target pressure increment dP is determined until the discharge side pressure reaches the stop pressure value P2, and the determined target pressure increment is determined. The discharge side pressure may be increased by dP. By gradually increasing the discharge side pressure in this way, it is possible to prevent the pressure tank 28 and the piping system from being damaged.

  Although one embodiment of the present invention has been described so far, it is needless to say that the present invention is not limited to the above-described embodiment, and may be implemented in various forms within the scope of the technical idea.

DESCRIPTION OF SYMBOLS 1 Water supply apparatus 2 Pump 3 Motor 4 Water pipe 5 Suction pipe 7 Water supply pipe 8 Bypass pipe 20 Inverter 21 Pressure sensor 22 Check valve 24 Flow switch 25 Backflow prevention device 26 Pressure sensor 28 Pressure tank 30 Cabinet 32 Discharge pipe 40 Control part 41 Eco driving button

Claims (6)

A pump for transferring water;
A motor for driving the pump;
A frequency converter for supplying electric power to the motor and operating the pump at a variable speed;
A pressure tank for holding the discharge side pressure of the pump;
A control unit for controlling the operation of the pump so as to maintain the target pressure,
The said control part is comprised so that a small water amount stop operation | movement may be performed in either the energy saving mode in which the time of the said small water amount stop operation | movement is shorter than the normal mode or the said normal mode.   2. The water supply device according to claim 1, wherein the control unit executes the small water amount stop operation in either the normal mode or the energy saving mode based on the latest operation history of the pump.   The low water amount stop operation includes a state watching operation in which a state where the amount of water used is small, and the time for the state watching operation in the energy saving mode is shorter than that in the normal mode. Or the water supply apparatus of 2.   The water supply device according to any one of claims 1 to 3, wherein the control unit controls the operation of the pump according to a target pressure control curve. The control unit selects one of a first target pressure control curve and a second target pressure control curve having a target pressure lower than that of the first target pressure control curve as the target pressure control curve. Configured to choose,
Based on the latest operation history, execute the small water volume stop operation in the normal mode and select the first target pressure control curve,
5. The water supply apparatus according to claim 4, wherein the water supply apparatus is configured to execute the low water volume stop operation in an energy saving mode and to select and operate the second target pressure control curve.   The eco-operation button for switching to the normal mode or the energy-saving mode is further provided, and when the eco-operation button is pressed, the control unit does not depend on the operation time of the pump immediately before the operation for stopping the small amount of water. The water supply device according to claim 3, wherein the small water amount stop operation is executed in an energy saving mode in which no watching operation is performed.

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