JPH0996278A - Variable speed water feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a frequent start/stop by stopping a supply water pump after a pressure is accumulated for a fixed time in a pressure tank when a small amount of water detection signal is generated by a flow switch, and starting the supply water pump when the pressure comes to be a pump start pressure preset value or less during stopping the supply water pump. SOLUTION: When a pressure value b a pressure detection means 6 is the lowest pressure or more at no-discharge operation time, and a flow switch 3 is in a closed condition of small amount of water, a small amount of water detection time timer is started. Pressure supervisory operation is then started, a supply water pump 1 is operated by a required frequency. When the flow switch 3 is closed, whether the present pressure is larger than a pressure PF or not is judged, in the case of decreasing the present pressure smaller than the pressure RF, the pressure is judged not in the small amount of water condition, the flow switch detection timer is reset, small amount of water detection action is canceled. On the other hand, when the small amount of water detection time timer performs a count up, a transfer is made to accumulating operation pressurizing water in a pressure tank 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a simple and small-sized variable speed water supply apparatus, and more particularly to a variable speed water supply apparatus having a small water quantity stop function for stopping a water supply pump when a load is a small amount of water.

[0002]

2. Description of the Related Art A variable speed water supply apparatus is a water supply apparatus capable of adjusting the flow rate and the discharge pressure by changing the rotational speed of a pump for supplying water according to a load by a variable speed means such as an inverter. FIG. 1 is an explanatory diagram showing the overall configuration of the variable speed water supply device. This variable speed water supply device sucks water from the suction port 11, pressurizes it with the water supply pump 1, and supplies the load 20 with water. On the discharge side of the water supply pump 1 of the flow path 10, a flow switch 3 that detects that the flow rate of the water flow is a small amount of water below a certain value, a check valve 4, and a pressure tank 5.
And pressure detecting means 6 for detecting the discharge side pressure of the pump (water pressure in the pressure tank). The pump 1 is driven by a frequency / voltage inverter which is a variable speed means 2 that changes its rotation speed, and the variable speed means 2 is controlled by a pump control means 7.

This pump control means 7 detects that the flow rate of the flow switch 3 is below a certain value, and generates a small water amount detection signal to maintain a constant small water amount detection time for a small amount of time. After confirming that the water quantity state has continued, the water tank 1 has a small water quantity stop function of stopping the water supply pump 1 after accumulating in the pressure tank 5 at a pressurizing pressure value or pressurizing frequency value for a certain period of time. Further, it has a pump starting pressure set value, and has a function of starting the water supply pump 1 when the pressure signal of the pressure detecting means 6 becomes equal to or lower than the pump starting pressure set value while the water supply pump is stopped.

Therefore, the operation of this variable speed water supply system is as follows. First, when the load 20 needs a medium water amount or a large water amount, the pump control means 7 uses the pressure signal S1 of the pressure detection means 6 to rotate the water supply pump 1 so that the pressure in the load 20 becomes constant. The means 2 is proportional-integral (PI) controlled. When the load is a small amount of water, the above-mentioned small amount of water stopping operation is performed in order to prevent heating due to the shutoff operation of the pump and to reduce wasteful operating time (energy saving). That is, the flow switch 3 detects a small amount of water and generates a detection signal, and after confirming that the small amount of water continues during a certain small amount of water detection time, the pressure tank 5 pressurizes for a certain time. Pressure is accumulated at a value or a pressurization frequency value, and then the water supply pump 1 is stopped. Then, when water is supplied from the pressure tank 5 to the load 20 and the pressure in the pressure tank 5 drops below a predetermined pump starting pressure set value, the water supply pump can be restarted to keep the water pressure in the load 20 at the predetermined pressure. Return to shifting operation.

[0005]

The purpose of the small water flow stop operation is to prevent the motor from being heated by the pump shutoff operation and to reduce the unnecessary operation time. On the contrary, the accumulated pressure during the small water flow stop operation is too high. Then, a rapid pressure increase due to the accumulated pressure before the pump is stopped is frequently repeated, which causes a problem to the mechanical life of the water supply device and also causes a problem such as frequent pressure fluctuations on the load side. Also, if the pressure rise value due to accumulated pressure before stopping a small amount of water is suppressed to a low level, there will be no sudden pressure rise on the load side, which will improve the usability of the water supply device. You will not be able to earn money and the frequency of starting and stopping the pump will increase.

By the way, the present inventor et al.
In patent application No. 527, a variable speed water supply device having means for automatically setting operating parameters of a pump including a pressurizing pressure (frequency) value and a small water amount detection time in accordance with load or data of the most recent operating condition is provided. Disclosure. It is also similarly disclosed that the means for automatically setting the operating parameters is based on the fuzzy inference function. According to such a variable speed water supply device, while the original purpose of the small water volume stop function of preventing heating by the pump shutoff operation and reducing the wasteful operation time is satisfied, the frequency of starting and stopping the pump is reduced, and the pressure is accumulated before the small water volume is stopped. It is possible to achieve the contradictory objectives of reducing the rapid pressure rise to some extent in a well-balanced manner.

However, the above-mentioned variable speed water supply apparatus has the following problems when applied to a simple and small-sized water supply apparatus. The number of input element signals (information) used for control increases, and the cost of the control device increases. When the fuzzy inference function is used, the amount of data increases and the memory capacity increases exponentially. Therefore, a large-capacity memory and a CPU having a high processing speed are required, which increases the price of the control device.

The present invention has been made in view of the above-mentioned circumstances, and even in a simple and small-sized economical water supply apparatus, avoiding a deadline operation and avoiding frequent start-stop, a well-balanced small amount of water is provided. It is an object of the present invention to provide a variable speed water supply device that can perform a stop operation.

[0009]

A variable speed water supply apparatus of the present invention comprises a water supply pump, variable speed means for changing the number of revolutions of the water supply pump, a flow switch provided on the discharge side of the water supply pump, and a check valve. A valve, a pressure tank and a pressure detecting means provided on the downstream side of the check valve, and a pump controlling means, wherein the pump controlling means generates a small amount of water detection signal by the flow switch, The water supply pump has a function of stopping the water supply pump after accumulating in the pressure tank at a certain pressurization pressure value or pressurization frequency value for a certain time after holding the water amount detection time, and a pump starting pressure set value. It has a function of starting the water supply pump when the pressure signal becomes less than or equal to the pump starting pressure set value by the pressure detection means during stop, and the small water amount detection time is the last pump stop time and the immediately preceding pump. luck Time and, based on the number of times of opening and closing of the flow switch, characterized in that a function for automatically setting.

Further, the control means starts the timer for the small water amount detection time after the flow switch is closed, performs the pressure monitoring operation with the frequency fixed and slightly increased, and counts up the timer to perform the pressure accumulation operation. It is characterized by entering.

Further, the control means starts the timer for the small water amount detection time after the flow switch is closed, performs the pressure monitoring operation with the frequency fixed, and enters the pressure accumulation operation by counting up the timer. It is characterized by being a thing.

Further, the control means starts the timer for the small water amount detection time and performs the pressure monitoring operation after the flow switch is closed, and the pressure accumulation operation is started by counting up the timer. Characterize.

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

By automatically adjusting the small water amount detection time by a fuzzy reasoning function or the like in accordance with the load or the data of the latest exercise condition, the optimum operating parameter corresponding to the variation of the load condition can be obtained. It becomes possible to adjust. Therefore, it is possible to reduce wasteful operation time due to the pump shutoff operation and 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 reduce the pressure fluctuation on the load side. A comfortable water supply system is provided.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the overall structure of a simple, compact and economical variable speed water supply system. As is clear from FIG. 1, a water feed pump 1, a variable speed means 2 for changing the rotation speed of the water feed pump 1, a flow switch 3 and a check valve 4 provided on the discharge side of the water feed pump, and a check valve. The configuration including the pressure tank 5 and the pressure detection means 6 provided on the downstream side is
This is similar to the variable speed water supply device described in the section of the related art.
In addition, the pump control means 7 causes the flow switch 3 to generate a small water amount detection signal S2 and hold it for a certain small water amount detection time, then accumulates pressure in the pressure tank 5 and then stops the water supply pump 1 And a pump starting pressure set value, and a starting function for starting the water feed pump 1 when the pressure signal S1 becomes less than or equal to the pump start pressure set value by the pressure detection means 6 while the water feed pump 1 is stopped. It is also the same as the above-mentioned conventional technique.

In the water supply system of this embodiment, the pump control means 7 is provided with automatic setting means for automatically setting an optimum value for the small water amount detection time for confirming the continuation of the small water amount state in accordance with the operating condition. Here, the operating status is, for example, the immediately preceding water supply pump operating time, the previous pump stop time, the number of times the flow switch is opened and closed, and the like. The means for automatically setting the small water detection time is based on the fuzzy inference function, which has a fuzzy inference section and rules, and takes in various information on driving conditions to extract inference results according to the rules of fuzzy inference. The value is newly set as an operation parameter.

FIG. 2 shows a flow of the operation for stopping a small amount of water.
First, it is determined that the current pressure detected by the pressure detecting means 6 is equal to or higher than the minimum pressure PB during the deadline operation (ST.
1). 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 there is a small amount of water supplied to the load side. YES
If that is the case, that is, if a small water quantity state is detected, the small water quantity detection time timer starts (ST3). Here, the timer value is automatically set from the data table by fuzzy inference. The details will be described later. Next, it is determined whether or not the timer has counted up (ST4). Whether or not the timer counts up is determined by 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 judged whether or not the pressure monitoring delay timer has counted up (ST7). Since the current pressure can be read by counting up this timer, the current pressure is the pressure when the flow switch is closed (P
It is determined whether it is larger than F) (ST8). If the current pressure is equal to or higher than the pressure PF when the flow switch is closed, it is determined that the small water amount state is continuing, and S
Returning to T2, after that, ST3, ST4, ST5, ST6,
The loop of ST7 will be repeated.

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

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

In the step (ST8) of confirming the present pressure, the present pressure is the pressure PF when the flow switch is closed.
When it is lower than that, it is determined that the state is not a small water amount state, the flow switch detection timer and the pressure monitoring detection timer are reset, and the small water amount detection operation is canceled. Similarly, when the current pressure is lower than the minimum pressure PB at the shutoff operation in the pressure confirmation step (ST1) immediately after the start, it is similarly judged that the state is not the small water amount state,
The low water volume stop condition is canceled. Also, a step of detecting whether the flow switch is open or closed (ST2)
In, when the flow switch is open, it is similarly determined that the flow rate is not in the small water amount state, and the small water amount stop operation is canceled.

FIG. 3 is a time chart showing an example of the small water amount stopping operation. At time T1, the previous pressure accumulation operation started,
The pump operation is stopped at time T2. Then, at time T3, it is detected that the pressure has dropped below the starting pressure, the pump is restarted, and variable speed (PI control) is performed so as to keep the pressure in 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 operating speed becomes zero until restart and the frequency rises. When the closing of the flow switch is detected at time T4, a small water amount detection time timer for confirming that the small water amount state has continued for a certain time is started. Then, the pump enters the pressure monitoring operation at a frequency that is slightly higher than the frequency when the flow switch detects the small water amount state. During this period, the small water amount detection time is excluded, except when the small water amount state is lost, such as when the flow switch is opened or the current pressure is lower than the pressure (PB) when the flow switch is closed. When is completed, the pump enters the pressure accumulation operation (ST9).

The small water amount detection time is a wait time for checking the continuation of the small water amount state, stopping the pump, and suppressing the start frequency. If the small water amount detection time is lengthened, it is possible to avoid repeated useless starting and stopping of the pump when there is a large amount of water fluctuation, but when no water is supplied, useless operation is performed during this period. On the contrary, if the small water amount detection time is shortened, useless operation is reduced when the waterless state continues for a long time, but there is an adverse effect that the stop / start frequency increases when the water amount fluctuation is large.

That is, it is possible to achieve the following in an appropriate balanced manner by automatically setting the small water amount detection time described above. Reduce the number of small water stop / starts (reduce the flow rate and pressure fluctuations by reducing the start frequency). Reduction of useless operating time (energy saving, prevention of heating due to pump deadline operation).

Here, the small water amount detection time is determined by fuzzy inference from the last stop time, the immediately preceding operation time, and the number of times the flow switch is opened and closed. The immediately preceding operation time is the time from when the pump is started to when the closing of the flow switch is detected, and is the time from T3 to T4 in FIG. still,
When the flow switch changes from the closed state to the open state during the pressure monitoring operation, the time from that point until the flow switch is closed again is added to the immediately preceding operation time. The number of times the flow switch is opened / closed is the number of times the flow switch has been opened / closed during the period from the time when the pressure accumulation operation was started last time (T1) until the small water amount detection time expires (T5). When the flow switch changes from closed to open during the pressure monitoring operation, the number of times of opening and closing is cumulatively counted.

For the small water amount detection time, referring to the data table, the data corresponding to the respective ranges of the three items of the last stop time, the immediately preceding operation time, and the flow switch opening / closing number are selected. If the flow switch changes from closed to open during pressure monitoring operation, the small water flow stop operation is canceled, the timer is reset, and when the flow switch is closed again, a new small water flow detection time is selected. Restart the pressure monitoring operation based on the above.

FIG. 4 shows a data table for selecting a small water amount detection time. Flow switch open / close frequency is low, medium,
There are three classifications, the last stop time is short and long,
The last driving time is divided into two categories, short and long. NA, NB, N
C, ND, and NE respectively represent the length of the small water amount detection time for detecting the closed state of the flow switch. Where: NA short time NB slightly short time NC medium ND slightly long time NE long time

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

Fuzzy inference with reference to this data table is performed 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 corresponding output value is referred at the time of input. The fuzzy inference rules this time have three inputs and one output, and the number of rules is relatively small, so there is no need for high-speed response, a relatively low-speed microcomputer is used, and the memory capacity is also small. Therefore, 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 constant end pressure control.

The variable speed water supply system incorporating the above-mentioned fuzzy inference mechanism was applied to a small-scale apartment house and a field test was conducted. As a result, when the data table of fuzzy inference is used, it is about 6 in comparison with the one which is not used.
It was confirmed that there was an effect of reducing the number of times a small amount of water stopped was about 0%. As for the small water stoppage time, the stoppage time per operation is about three times longer than that when automatic setting by fuzzy reasoning is not used, and it can be seen that an appropriate small water stoppage is performed. The pressure setting value when accumulating is
In this embodiment, the pressure is set slightly higher than the required minimum pressure (PB). The pressurizing pressure during accumulating can be found by fuzzy reasoning, but the setting range of the pressure during accumulating is narrow in comparison with the need for complicated calculation, so even if a fine setting is made within that range, it is large. This is because the effect cannot be expected. Therefore, by setting the pressure set value at the time of pressure accumulation to a predetermined fixed set value, it is possible to perform a sufficiently effective small water amount stop operation.

In this embodiment, another fuzzy controller is used to perform inference in advance and the inference result is made into a data table to set the small water amount detection time. However, it is not limited to fuzzy inference, but fuzzy inference is possible. By using inference, it is possible to perform control so as to obtain a desired operating state for all load conditions, and to reflect empirical knowledge in the control content. Further, it goes without saying that the division of the data table may be increased more than in the above-described embodiment.

[0033]

According to the present invention, the number of input / output points relating to control can be reduced, the control contents can be simplified, and the memory capacity can be reduced by forming a simple data table. The small water amount detection time relating to the small water amount stop operation of the variable speed water supply apparatus can be automatically set so that the state is brought into the state. That is, it is possible to achieve a reduction in the frequency of operation stop (startup) with a simple and small water supply device while satisfying the purpose of the operation for stopping a small amount of water such as prevention of heating by the pump shutoff operation and reduction of operation time.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an overall configuration of a variable speed water supply device.

FIG. 2 is an explanatory diagram showing a flow of a small water amount stop operation.

FIG. 3 is a time chart showing an example of a small water amount stop operation.

FIG. 4 is an explanatory diagram showing an example of a table for inferring a small water amount detection time.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Water supply 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

Claims (5)

[Claims] 1. A water supply pump, a variable speed means for changing the rotational speed of the water supply pump, a flow switch and a check valve provided on the discharge side of the water supply pump, and a downstream side of the check valve. A pressure tank, a pressure detection means, and a pump control means are provided, and the pump control means generates a small water amount detection signal by the flow switch and holds the small water amount detection time for a certain time, and then the pressure tank has a fixed time. Has a function of stopping the water supply pump after accumulating at a certain pressurization pressure value or pressurization frequency value, and a pump starting pressure set value, and a pressure signal is sent by the pressure detection means while the water supply pump is stopped. It has a function of starting the water supply pump when it becomes less than or equal to the starting pressure set value, and the small water amount detection time is the last pump stop time, the immediately preceding pump operation time, and the number of times the flow switch is opened and closed. Based on the variable speed water supply apparatus characterized by comprising a function for automatically setting. 2. The control means starts a timer for a small amount of water detection time after the flow switch is closed and performs a pressure monitoring operation in which the frequency is fixed and slightly increased, and the pressure accumulation operation is performed by counting up the timer. The variable speed water supply device according to claim 1, wherein the variable speed water supply device enters. 3. The control means, after the flow switch is closed, starts a timer for detecting a small amount of water and performs a pressure monitoring operation with the frequency fixed as it is,
The variable speed water supply device according to claim 1, wherein the pressure accumulation operation is started by counting up the timer. 4. The control means, after the flow switch is closed, starts a timer for a small amount of water detection time, performs a pressure monitoring operation, and counts up the timer to enter the pressure accumulation operation. The variable speed water supply device according to claim 1. 5. The variable speed water supply apparatus according to claim 2, wherein the means for automatically setting the small water amount detection time is performed by fuzzy inference with reference to a data table. .