JP3979984B2 - Water supply equipment - Google Patents

Description

  The present invention relates to a simple and small-sized water supply device, and more particularly to a water supply device having a small water amount stop function for stopping a water supply pump when a load is a small amount of water.

  The variable speed water supply apparatus is a water supply apparatus that can adjust the flow rate and the discharge pressure by changing the rotation speed of a pump that supplies water in accordance with a load by a variable speed means such as an inverter. Drawing 1 is an explanatory view showing the whole variable speed water supply system composition. This variable speed water supply device sucks water from the suction port 11, pressurizes it with the water supply pump 1, and supplies water to the load 20. On the discharge side of the water supply pump 1 in the flow path 10, a flow switch 3, a check valve 4, a pressure tank 5, and a discharge side pressure of the pump for detecting that the flow rate of the water flow is a small amount of water below a certain value. Pressure detecting means 6 for detecting (water pressure in the pressure tank) is provided. The pump 1 is driven by a frequency / voltage inverter that is a variable speed means 2 that changes its rotational speed, and the variable speed means 2 is controlled by a pump control means 7.

  The pump control means 7 detects that the flow switch 3 has a flow rate of the flow path 10 below a certain value, generates a small water amount detection signal, holds a constant small water amount detection time, and the small water amount state is maintained. After confirming that the pressure tank 5 has been continued, the pressure tank 5 has a function of stopping a small amount of water after the pressure tank 5 is accumulated at a pressurized pressure value or a pressurized frequency value for a certain period of time. Also, it has a pump start pressure set value, and has a function of starting the feed water pump 1 when the pressure signal of the pressure detecting means 6 becomes equal to or lower than the pump start pressure set value while the feed water pump is stopped.

  Therefore, the operation of this variable speed water supply apparatus is as follows. First, when the load 20 requires a medium or large amount of water, the pump control means 7 rotates the feed water pump 1 from the pressure signal S1 of the pressure detection means 6 so that the pressure at the load 20 becomes constant. The means 2 is controlled by proportional integration (PI). When the load is a small amount of water, the above-described operation for stopping the small amount of water is performed in order to prevent heating due to the shutoff operation of the pump and to reduce useless operation time (energy saving). That is, the flow switch 3 detects a small amount of water and generates a detection signal. After confirming that the small amount of water continues for a certain amount of water detection time, the pressure pressure in the pressure tank 5 is constant for a certain period of time. The pressure is accumulated at the value or the pressurization frequency value, and then the water supply pump 1 is stopped. When water is supplied from the pressure tank 5 to the load 20 and the pressure in the pressure tank 5 falls below a predetermined pump start pressure set value, the water supply pump is started again, and the water pressure at the load 20 can be maintained at the predetermined pressure. Return to shifting operation.

  The purpose of the low water volume stop operation is to prevent heating by the pump shutoff operation and to reduce wasteful operation time, but conversely, if the accumulated pressure during this small water volume stop operation is too high, a sudden pressure due to the accumulated pressure before the pump stops The rise will be repeated frequently, which will cause a problem in the mechanical life of the water supply device, and problems such as frequent pressure fluctuations on the load side will occur. In addition, if the pressure increase due to pressure accumulation before the stoppage of a small amount of water is kept low, there will be no sudden pressure rise on the load side and the usability as a water supply device will be improved. Can not earn, the frequency of starting and stopping the pump will increase.

  In the meantime, the present inventors, in Japanese Patent Application No. 5-240527, applied the pump operating parameters including the pressurized pressure (frequency) value and the small water amount detection time according to the data of the load or the latest operating condition. A variable speed water supply apparatus having means for automatically setting is disclosed. It is also disclosed that the means for automatically setting the operation parameter is based on a fuzzy inference function. According to such a variable speed water supply device, while satisfying the purpose of the original low water volume stop function of preventing the heat by the pump shut-off operation and reducing the wasteful operation time, the pump start / stop frequency is reduced, and the pressure is accumulated before the low water volume stop. The conflicting objectives of reducing the sudden pressure rise can be achieved with a certain degree of balance.

However, the variable speed water supply apparatus described above has the following problems when applied to a simple and small-sized water supply apparatus.
(1) The number of input element signals (information) used for control increases, and the price of the control device increases.
(2) When the fuzzy inference function disclosed in Japanese Patent Application No. 5-240527 is used, the amount of data increases and the memory capacity increases exponentially. For this reason, a large-capacity memory and a CPU with a high processing speed are required, and the price of the control device increases.

  The present invention has been made in view of the above-described circumstances. Even in a simple and small-sized economical water supply apparatus, a balanced low water quantity stopping operation is performed while avoiding a deadline operation and frequent starting and stopping. It aims at providing the water supply apparatus which can be used.

In order to achieve the above-described object, a water supply apparatus of the present invention includes a pump, pressure detection means provided on the discharge side of the pump, variable speed means for changing the rotation speed of the pump, and a load with a small amount of water. In a water supply apparatus comprising a control means having a small water amount stop function that sometimes stops the pump, the control means, when in a low water amount state, the rotational speed of the pump when in a low water amount state The pump is stopped when it is determined that the detected pressure of the pressure detecting means does not drop below a predetermined pressure for a certain period of time.

According to an aspect of the present invention, a pressure tank is provided on the discharge side of the pump, and the control unit pressurizes water into the pressure tank with a set pressurization pressure when the water volume is low, and stops the pump.
According to one aspect of the present invention, the predetermined pressure is a pressure value lower than the pressure when the small water amount state is reached.

  A preferable aspect of the water supply apparatus of the present invention includes a water supply pump, variable speed means for changing the rotation speed of the water supply pump, a flow switch and a check valve provided on the discharge side of the water supply pump, A pressure tank and pressure detection means provided on the downstream side; and a pump control means. The pump control means generates a low water amount detection signal after the flow switch generates a low water amount detection time, and The pressure tank has a function of stopping the feed water pump after accumulating at a certain pressurized pressure value or pressurized frequency value for a certain period of time, and a pump starting pressure set value, and the pressure detecting means while the feed water pump is stopped. A function of starting the water supply pump when a pressure signal becomes equal to or lower than the pump start pressure set value, and the low water amount detection time includes a previous pump stop time, a previous pump operation time, and the flow Based on the number of times of opening and closing of switches, and a function of automatically setting.

  In addition, the control means starts a timer for detecting a small amount of water after the flow switch is closed, performs a pressure monitoring operation with a slight increase in frequency, and enters the pressure accumulation operation by counting up the timer. It is.

  Further, after the flow switch is closed, the control means starts a timer for detecting a small amount of water and performs a pressure monitoring operation with a fixed frequency, and enters the pressure accumulating operation by counting up the timer. .

  Further, after the flow switch is closed, the control means starts a timer for detecting a small amount of water and performs a pressure monitoring operation, and enters the pressure accumulation operation by counting up the timer.

  The means for automatically setting the small water amount detection time is performed by fuzzy inference with reference to a data table.

  According to the present invention, it is possible to reduce the wasteful operation time due to the pump shut-off operation, contribute to energy saving, avoid a sudden increase in the discharge side pressure of the pump, extend the mechanical life of the water supply system, and A comfortable water supply device with less pressure fluctuation is provided.

  According to the present invention, it is possible to achieve a reduction in the frequency of operation stop (start) with a simple and small water supply device while satisfying the objectives of a small water amount stop operation such as prevention of heating by pump shut-off operation and reduction in operation time. .

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing the overall configuration of a simple, small and economical variable speed water supply apparatus. As apparent from FIG. 1, the feed water pump 1, the variable speed means 2 for changing the rotation speed of the feed water pump 1, the flow switch 3 and the check valve 4 provided on the discharge side of the feed water pump, and the check valve The configuration comprising the pressure tank 5 and the pressure detection means 6 provided on the downstream side is the same as that of the variable speed water supply apparatus described in the section of the prior art. Further, the pump control means 7 generates a small amount of water detection signal S2 and holds the small amount of water detection time, then accumulates pressure in the pressure tank 5, and then stops the water supply pump 1 after that. And a start function for starting the feed water pump 1 when the pressure signal S1 falls below the pump start pressure set value by the pressure detecting means 6 while the feed water pump 1 is stopped. It is the same as that of the above-mentioned prior art.

  In the water supply apparatus of the present embodiment, the pump control means 7 is provided with an automatic setting means 15 for automatically setting an optimum value for the small water amount detection time for confirming the continuation of the small water amount state according to the operation state. Here, the operating status is, for example, the immediately preceding feed water pump operating time, the previous pump stop time, the number of times of opening and closing the flow switch, and the like. The means for automatically setting the small water detection time is based on the fuzzy reasoning function, which has a fuzzy reasoning part and rules, extracts various information on the operating status, extracts the reasoning results according to the rules of fuzzy reasoning, and A new value is set as an operation parameter.

  FIG. 2 shows a flow of a small water amount stop operation. First, it is determined that the current pressure detected by the pressure detection means 6 is equal to or higher than the minimum pressure PB during the shut-off operation (ST1). If this is YES, it is determined whether the flow switch is closed or open (ST2). The fact that the flow switch is closed indicates that the amount of water supplied to the load side is almost small. If YES, that is, if a small water amount state is detected, a small water amount detection time timer is started (ST3). Here, the timer value is automatically set from the data table by fuzzy inference. Details of this will be described later. Next, it is determined whether or not the timer has counted up (ST4). Whether or not the timer has counted up is determined whether or not a predetermined small water amount detection time has elapsed.

  At this stage, if the answer is NO, the timer is not counting up, so the pressure monitoring operation is started (ST5). In this operation, the pump is operated at a constant frequency slightly higher than the frequency when the flow switch is closed. Then, the pressure monitoring delay timer starts (ST6). This timer is a short-time timer of about several seconds, and it is determined whether or not the pressure monitoring delay timer has been counted up (ST7). Since the current pressure can be read by counting up the timer, it is determined whether or not the current pressure is higher than the pressure (PF) when the flow switch is closed (ST8). When the current pressure is equal to or higher than the pressure PF when the flow switch is closed, it is determined that the low water amount state continues, and the process returns to ST2, and thereafter the loop of ST3, ST4, ST5, ST6, ST7 is repeated. It will be.

In the pressure monitoring operation, the pump may be operated with the pressure frequency fixed when the flow switch is closed. In this case, the pressure value (PF) for comparison is slightly lowered and calculated as, for example, 95%, pressure monitoring operation is performed, and then pressure accumulation operation is started.
Further, in the pressure monitoring operation, the variable speed (PI) control operation in which the supply end pressure is kept constant without fixing the pressurization frequency may be continued.

  When the timer counts up in ST4 and becomes YES, it is confirmed that the low water amount state has continued for a certain period of time. Then, the pressure accumulation operation for pressurizing water to the pressure tank is started (ST9). That is, it means that the flow switch is never opened during this small water amount detection time. The pressure accumulation operation is performed at a predetermined set pressure (or frequency).

  If the current pressure is lower than the pressure PF when the flow switch is closed in the current pressure confirmation step (ST8), it is determined that the water flow is not low, and the flow switch detection timer and the pressure monitoring detection timer are reset. The small water amount detection operation is canceled. Similarly, when the current pressure is lower than the minimum pressure PB during the shut-off operation in the pressure confirmation step (ST1) immediately after the start, it is similarly determined that the water amount is not low, and the low water amount stop state is cancelled. The Further, in the step (ST2) of detecting that the flow switch is open or closed, when the flow switch is open, it is similarly determined that there is no small water amount state, and the small water amount stop operation is cancelled.

  FIG. 3 is a time chart showing an example of the operation for stopping a small amount of water. At the time T1, the previous pressure accumulation operation is started, and at the time T2, the pump operation is stopped. Then, at time T3, it is detected that the pressure has dropped below the starting pressure, the pump is started again, and variable speed (PI control) is performed so as to keep the pressure at the terminal water supply device constant. The time from this time T2 to T3 is stored in the control device as the previous stop time. That is, the previous stop time is the stop time from when the pump operation speed becomes zero until the frequency increases after restarting. When the flow switch close is detected at time T4, a small water amount detection time timer is started to confirm that the low water amount state has continued for a certain period of time. Then, the pump enters the pressure monitoring operation at a constant frequency that is slightly higher than the frequency when the flow switch detects the low water amount state. During this time, the low water amount detection time except when the low water amount state is lost, such as when the flow switch is opened or the current pressure drops below the pressure (PF) when the flow switch is closed Expires, the pump enters a pressure accumulation operation (ST9).

  The small water amount detection time is a time for checking the continuation of the small water amount state, stopping the pump, and suppressing the start frequency. If this small amount of water detection time is lengthened, it is possible to avoid repeated start and stop of the pump when the amount of water fluctuation is large, but when the non-water supply continues, useless operation is performed during this time. On the contrary, if the detection time for the small amount of water is shortened, useless operation is reduced when the non-water supply state continues for a long time, but there is an adverse effect that the frequency of stopping / starting increases when the amount of water fluctuation is large.

In other words, the following (1) and (2) can be achieved with an appropriate balance by the automatic setting of the small water amount detection time described above.
(1) Reduce the number of times of stopping and starting with a small amount of water (reducing flow rate fluctuations and pressure fluctuations by reducing the starting frequency).
(2) Reduction of wasted operation time (energy saving, prevention of heating by pump shutoff operation).

Here, the small water amount detection time is determined by fuzzy inference from the previous stop time, the previous operation time, and the flow switch opening / closing frequency. The immediately preceding operation time is the time from when the pump is started until the flow switch is detected to be closed, and is the time from T3 to T4 in FIG. When the flow switch is changed from the closed state to the open state during the pressure monitoring operation, the time from the time point until the flow switch is closed again is added to the previous operation time.
The flow switch open / close count is the number of times the flow switch is opened / closed during the time from when the previous pressure accumulation operation was started (T1) until the low water amount detection time expired (T5). When the flow switch is switched from closed to open during pressure monitoring operation, the number of open / close operations is counted.

  For the small water amount detection time, data corresponding to each of the three ranges of the previous stop time, the previous operation time, and the flow switch opening / closing frequency is selected with reference to the data table. If the flow switch is opened from the closed state during pressure monitoring operation, the small water volume stop operation is canceled, the timer is reset, and when the flow switch is closed again, a new low water volume detection time is selected, and the time Restart the pressure monitoring operation based on

FIG. 4 shows a data table for selecting a small water amount detection time. The flow switch opening / closing frequency is classified into three categories of small, medium, and large, the previous stop time is classified into two categories of short and long, and the immediately preceding operation time is classified into two categories of short and long. NA, NB, NC, ND, NE represent the length of the small water amount detection time for detecting the closed state of the flow switch.
here,
NA Short time NB Some short time NC Medium ND Some long time NE Long time

  Therefore, for example, when the number of times of opening and closing the flow switch is small, the previous operation time is short, and the previous stop time is short, the small water amount detection time is NC (medium). Thus, the time for detecting that the flow switch is closed is obtained by referring to the table of the number of times of opening / closing the flow switch, the previous operation time, and the previous stop time.

  Performing fuzzy inference with reference to this data table is supported by software using a general-purpose microcomputer. This method is a method in which the result of fuzzy inference is written in the ROM as discrete data in advance and the output value corresponding to the input is referred to. The rules for fuzzy reasoning this time are three inputs and one output, and since the number of rules is relatively small, there is no need for high-speed response, a relatively low-speed microcomputer is used, and the memory capacity is small. For this reason, the manufacturing cost of the control circuit portion can be suppressed. The microcomputer used for fuzzy inference can be shared with the microcomputer because the microcomputer has already been adopted for the terminal pressure constant control.

A field test was conducted by applying the variable speed water supply system incorporating the fuzzy inference mechanism described above to a small apartment house. As a result, it was confirmed that when the fuzzy inference data table is used, there is an effect of reducing the number of times of stoppage of a small amount of water by about 60% as compared with the case of not using it. As for the low water amount stop time, the stop time per one time is about three times longer than when automatic setting by fuzzy inference is not used, and it can be seen that an appropriate low water amount stop is being performed.
Note that the pressure set value at the time of pressure accumulation is a pressure slightly higher than the necessary minimum pressure (PB) in this embodiment. The pressurization pressure at the time of pressure accumulation can be obtained by fuzzy inference, but the setting range that can be taken by the pressure at the time of pressure accumulation is narrow for complicated calculation, so even if fine settings are made within that range This is because the effect cannot be expected. Therefore, by setting the pressure setting value at the time of pressure accumulation to a predetermined constant value, it is possible to perform a sufficiently small water amount stopping operation.

  In this embodiment, inference was performed in advance by another fuzzy controller and the inference result was converted into a data table and the low water amount detection time was set, but this is not limited to fuzzy inference, but fuzzy inference is used. Thus, it is possible to perform control to obtain a desired operating state for any load situation, and to reflect experience knowledge in the control content. Of course, the data table may be divided more than in the above-described embodiment.

Explanatory drawing which shows the whole structure of a variable speed water supply apparatus. Explanatory drawing which shows the flow of small water quantity stop operation | movement. The time chart which shows an example of small water stop operation | movement. Explanatory drawing which shows an example of the table which infers small water amount detection time.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Feed water pump 2 Variable speed means 3 Flow switch 4 Check valve 5 Pressure tank 6 Pressure detection means 7 Pump control means 10 Flow path 11 Suction port 15 Automatic setting means 20 Load

Claims (3)

A pump,
Pressure detecting means provided on the discharge side of the pump;
Variable speed means for changing the rotational speed of the pump;
In a water supply apparatus comprising a control means having a small water amount stop function for stopping the pump when the load is a small amount of water,
When the low water amount state is reached, the control means fixes the rotation speed of the pump to the rotation speed when the low water amount state is reached, and the detection pressure of the pressure detection means does not drop below a predetermined pressure for a certain period of time. The water supply device is characterized in that the pump is stopped.   The pressure tank is provided on the discharge side of the pump, and the control means pressurizes water to the pressure tank with a set pressurization pressure when the water volume is low, and stops the pump. Water supply equipment.   The water supply device according to claim 1 or 2, wherein the predetermined pressure is a pressure value lower than a pressure when a small amount of water is reached.

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