JPH05195960A - Pump controller - Google Patents

Abstract

PURPOSE:To stabilize operation by comparing pressure difference between the load feed side and return side with two high-low set values at a specified sampling interval, and adding 1 to the pump number set value at the time of being the low set value or less, while subtracting 1 from the set value at the time of being the high set value or more, thereby controlling the number of pumps to be operated according to the added-subtracted count number. CONSTITUTION:The pressure difference of a heating medium flowing in feed-side and return-side pipelines 8A, 8C connecting pumps 6A-6C to air-conditioning units 2A-2C is detected by a differential pressure gauge 9 and inputted into a pump controller 7. In the pump controller 7, this differential pressure is compared with the first low set value by a comparator 703 and with the second high set value by a comparator 704 at a specified interval. The result is sent to an adding-subtracting counter 705 so as to add 1 to the count in the case of being the first set value or less and to subtract 1 from the count in the case of being the second set value or more. A control signal output part 708 then reads the count result at a specified interval and controls the number of pumps to be operated according to the count number.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pump controller for controlling a plurality of pumps connected to a single piping system on the basis of pressure data of the single piping system. The present invention relates to a pump controller that controls a pump when a piping system includes a plurality of loads that form flow paths connected in parallel.

[0002]

2. Description of the Related Art Conventionally, for example, when a heat medium is circulated from a heat source device 1 to a plurality of air conditioning units 2A, 2B, 2C, a configuration as shown in FIG. 4 has been used. That is, a pipe 8B is connected to the heat medium outlet of the heat source device 1, and pumps 6A, 6B, 6C for pumping the heat medium are connected in parallel to the other end of the pipe 8B with the suction side being the pipe 8B side. There is.
Check valves 5A, 5B, 5C are connected to the heat medium outlet sides of the pumps 6A, 6B, 6C, respectively.
The outlet side pipes of B and 5C are connected to one pipe 8C. Plural branches are provided in the pipe 8C, and the stop valves 3A, 3B, 3C are connected to the respective branches. The stop valve 3
Air conditioning units 2A, 2B,
2C is connected, and the heat medium outlet sides of the air conditioning units 2A, 2B, 2C are connected to the pipe 8A. The end of the pipe 8A is connected to the heat medium inlet of the heat source device 1,
The heat medium is driven by the pumps 6A, 6B, 6C, and the check valves 5A, 5B, 5C, the pipe 8C, the stop valves 3A, 3B,
3C, the air conditioning units 2A, 2B and 2C, the pipe 8A, the heat source device 1, and the pipe 8B are circulated in this order.

A pressure detector for detecting the pressure of the heat medium in the pipe is provided upstream of the plurality of branches of the pipe 8C and downstream of any of the connecting portions of the air conditioning units 2A, 2B, 2C of the pipe 8A. The outputs of these pressure detectors are installed and input to a differential pressure gauge 9 which calculates and outputs the differential pressure between the pressure of the heat medium in the pipe 8C and the pressure of the heat medium in the pipe 8A. The output of the differential pressure gauge 9 is input to the pump controller 7, and the pump controller 7 controls the number of operating pumps based on the input differential pressure.

All of the air conditioning units 2A, 2B and 2C are not always used, and the number of air conditioning units through which the heat medium is actually flown depends on the usage condition of the room in which they are installed. The valve opens and closes and changes arbitrarily,
Along with this, the total cross-sectional area of the flow path of the heat medium connecting the pipes 8C and 8A changes. In order to maintain the amount of heat medium flowing through the air conditioning unit in use at a predetermined amount, it is necessary to change the amount of heat medium sent into the pipe 8C in accordance with the change in the total cross-sectional area.

When any one of the stop valves is closed while a constant flow rate of the heat medium is being sent to the pipe 8C, the total cross-sectional area changes, and the heat medium flow path connecting the pipes 8C and 8A is formed. The flow velocity of the heat medium flowing through a certain air conditioning unit changes. When the flow velocity changes, the pressure difference between the inlet and outlet of the flow path (the differential pressure calculated by the differential pressure gauge 9 in FIG. 4, hereinafter referred to simply as the differential pressure) changes. By capturing this differential pressure, the number of operating pumps is increased or decreased. As shown in FIG. 6, the pump controller 7 is provided with comparators PA, PB, and PC corresponding to each pump, and when the input differential pressure exceeds the set pressure ΔPB of the comparator PB, the pump 6B is stopped. The pump 6B is activated when the differential pressure that is input reversely falls below the set pressure ΔPB of the comparator PB. The pumps 6A and 6C are also started or stopped according to the operation of the comparators PA and PC, respectively. For example, as shown in FIG. 5, the horizontal axis represents the magnitude of the differential pressure ΔP, the vertical axis represents the number of operated pumps, and the pumps 6B, 6 are operated at the differential pressure ΔPo.
It is assumed that two Cs are in operation. Stop valves 3A, 3B,
When any of the 3C is closed slightly, the detected differential pressure gradually rises and exceeds ΔPBL, and eventually ΔPBH.
Reach ΔPBH and ΔPBL are the boosting side operating pressure and the stepping down side operating pressure of the comparator PB at the set value ΔPB, and the interval between them is called the dead zone. When the differential pressure exceeds ΔPBH, the comparator PB operates, the pump 6B is stopped, and the number of operating pumps becomes one. When the pump 6B is stopped, the amount of the heat medium sent to the pipe 8C is reduced and the pressure in the pipe 8C is reduced, so that the detected differential pressure is also reduced to ΔPBH or less.

Next, when the stop valve closed earlier is opened in the opposite direction, the cross-sectional area of the flow passage gradually increases and the differential pressure gradually decreases. The detected differential pressure exceeds ΔPB and ΔPBL
When it goes down, the comparator PB operates in the opposite direction to the previous one,
The pump 6B is activated. When the stop valve is further opened to decrease the differential pressure, and when the detected differential pressure exceeds ΔPA and falls below ΔPAL, the comparator PA operates and the pump 6A is activated to operate three pumps.

[0007]

Since the operating number control is performed as described above, it is unavoidable to provide the same number of comparators as the number of pumps and to set the set pressure of each comparator in a stepwise manner. We had to allow the differential pressure that we wanted to maintain to a value to fluctuate with the load fluctuation. Further, if the width of the step-like setting is narrowed, the pump is frequently started and stopped, causing a hunting state, and setting itself is difficult. Generally, in the discharge pressure (H) -flow rate (Q) characteristic of the pump, as shown in FIG. 7, since the change rate of the discharge pressure (H) is small with respect to the change rate of the flow rate (Q), it is However, even if the range of set values was narrowed, the hunting state was likely to occur, and the number of operating vehicles was not easily switched.

An object of the present invention is to minimize the allowable range of fluctuation of the pressure difference between both ends of the load and maintain stable pump operation in a configuration in which the number of operating pumps is switched according to the fluctuation of the load. ..

[0009]

In order to achieve the above object, the present invention provides a plurality of pumps for pumping a fluid, and a first pump connected to the plurality of pumps for delivering the fluid to a plurality of loads. Pressure system for detecting the pressure difference between the fluids flowing through the first and second piping systems, and the second piping system for circulating the fluids passing through the plurality of loads to the plurality of pumps. In a pump controller that controls start and stop of the plurality of pumps of a piping device including a detection unit based on an output of the differential pressure detection unit, an output value of the differential pressure detection unit and a first set value are predetermined. And a second comparing unit that outputs a signal when the output value of the differential pressure detecting unit is small and that is larger than the output value of the differential pressure detecting unit and the first set value. Set value and the predetermined sampling interval The second comparing means for comparing and outputting a signal when the output value of the differential pressure detecting means is large, and the setting value is incremented by 1 when the signal is output from the first comparing means, and the second value is increased. A counter that decrements the set value by 1 when a signal is output from the comparison means, and a control signal output that reads out the set value of the counter at a predetermined sampling interval and outputs a signal for operating the pump corresponding to the read number. And means.

The above-mentioned problem is also to provide a pump controller for controlling the start and stop of the pump of a cooling and heating system in which a heat medium heated and / or cooled by a heat source device is conveyed to a plurality of air conditioners by a plurality of pumps. A differential pressure detector that detects the differential pressure between the header and the inlet header of the heat source device, a comparator that outputs a signal to increase the number of pumps that operate using the differential pressure value as an input, and the differential pressure value that is input That outputs a signal for reducing the number of pumps that operate by one, an astable multivibrator that periodically generates a signal that enables the outputs of the two comparators, and the two comparators It is also achieved by including an increment / decrement counter for increasing / decreasing the number of operating pumps with the signal output from the input.

[0011]

The first comparing means compares the differential pressure output from the differential pressure detecting means with the first set value at a predetermined sampling interval, and the differential pressure output from the differential pressure detecting means is the first differential value. When it is lower than the set value, a signal is output to the control signal output means.
The second comparison means compares the differential pressure output from the differential pressure detection means with a second set value at a predetermined sampling interval, and the differential pressure output from the differential pressure detection means is lower than the second set value. When it is also high, a signal is output to the control signal output means. The counter increments the value stored by the input signal from the first comparison means to 1
The value stored in the input signal from the second comparison means is decreased by one. The control signal output unit reads out the set value of the counter at a predetermined sampling interval and outputs a control signal for operating the number of pumps corresponding to the read numerical value.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. In the embodiment shown in FIG. 1, an increasing comparator Pi701 to which the differential pressure ΔP output from the differential pressure gauge 9 is input,
Similarly, a reduction comparator Pd702 to which the differential pressure ΔP output from the differential pressure gauge 9 is input, and a pulse signal having a pulse width of about 0.5 seconds at a predetermined interval (about 5 seconds but variable within a range of several seconds to several tens of seconds). 706 that oscillates
And a first AND circuit 703 which receives the output of the increasing comparator Pi701 and the output signal of the astable multivibrator 706, the output of the decreasing comparator Pd702 and the astable multivibrator 70.
Second AND circuit 704 to which the output signal of 6 is input
And the first AND circuit 703 and the second AND circuit 7
When the output of 04 is input, and the signal is input from the first AND circuit 703, the value of the counter incorporated is increased by 1,
When a signal is input from the second AND circuit 704, an increment / decrement counter 705 that decrements the value of the counter by 1 and a pump control signal that is connected to the increment / decrement counter 705 and reads out the value of the counter at a predetermined sampling interval And a control signal output unit 708 for outputting a voltage, and an operation switch 707 connected to the astable multivibrator 706 and the increment / decrement counter 705 to apply a voltage. The operation switch 707 is interlocked with a start switch of a pump group (not shown).

The increase comparator 701 has a set value Δ
The signal is output only at the step-down operating pressure ΔPiL with respect to Pi,
The decrease comparator 702 sets the set value to ΔPd as follows.
The signal is output only at the boost side operating pressure ΔPdH. ΔPi and ΔPd are set in the relationship shown in FIG. 2 so that the desired differential pressure is between ΔPi and ΔPd in a normal operating state.

The control signal output unit 708 outputs a control signal so that the number of pumps set in the counter is always operating.

Hereinafter, the pump controller 70 having the above configuration will be described.
The operation of the system installed by replacing 0 with the pump controller 7 of FIG. 4 will be described. It is assumed that the stop valves 3A, 3B, 3C are all open. When the start switch of the pump group is turned on and the system is started, the operation switch 70
7, the astable multivibrator 706 is activated, and the oscillation of the pulse signal is started at intervals of about 5 seconds. At the same time, the operation switch 707 is added to the increment / decrement counter 705.
The voltage is applied to the counter and the counter is reset (the counter is set to 0). Since the increment / decrement counter 705 is 0, the number of operating pumps is still zero.

The differential pressure gauge 9 calculates the differential pressure between the two based on the pressure signals input from the pressure detectors of the pipes 8C and 8A and sends it to the increase comparator 701 and the decrease comparator 702. Since the pump has not been operated yet, the differential pressure to be input is, of course, equal to or lower than the step-down side operating pressure ΔPiL, and the increasing comparator 701 outputs a signal but the decreasing comparator 702 does not output a signal. The AND circuit 703 receives the signal from the increment comparator 701 and then the pulse signal of the astable multivibrator 706, and outputs the signal to the increment / decrement counter 705. Since the AND circuit 704 does not receive the input from the decrease comparator 702, it does not output it. The increment / decrement counter 705 receives a signal from the AND circuit 703 and sets the counter to 1, and the control signal output unit reads the value 1 of the counter and outputs a control signal for activating one of the pumps to cause the pump to operate. One is started.

Since the astable multivibrator 706 outputs a signal at intervals of about 5 seconds, the AND circuit 703 also outputs a signal at intervals of about 5 seconds. When all stop valves 3A, 3B, 3C are open, the flow rate is insufficient with one pump,
The differential pressure also does not reach the desired differential pressure. Therefore, the AND circuit 70
About 5 seconds after the signal is first output from 3, the AND condition of the AND circuit 703 is satisfied again, and the signal is output to the increment / decrement counter 705. In response to this signal, the increment / decrement counter 705 increments the numerical value of the counter to 2, and activates one more control signal output unit pump. When the same procedure is repeated and all three pumps are started, the differential pressure becomes a desired value (a value between ΔPi and ΔPd), and the heat medium of a predetermined flow rate is supplied to each air conditioning unit.

As mentioned above, the astable multivibrator 706 outputs a signal at intervals of about 5 seconds, so that the pump controller monitors the differential pressure at a sampling interval of about 5 seconds during the operation of the pump. As described above, when three stop pumps are closed while three pumps are operating, the differential pressure increases. When the differential pressure exceeds ΔPdH, the decrease comparator Pd702 operates and outputs a signal to the AND circuit 704. In the AND circuit 704, the AND condition is satisfied by the input from the decreasing comparator Pd 702 and the pulse signal input from the astable multivibrator 706 at intervals of about 5 seconds, and the signal is output to the increment / decrement counter 705. At this time, since the increasing comparator Pi701 does not operate, there is no signal output from the AND circuit 703 to the increment / decrement counter 705, and the increment / decrement counter 705 receives the signal input from the AND circuit 704 and decrements the counter value by one. At the same time, it outputs a signal to reduce the number of operating pumps to two. The detected differential pressure decreases when the selected pump is stopped, but when it becomes smaller than ΔPiL, the increasing comparator Pi701 operates to increase the number of pumps operating again and the operation becomes unstable. .. Therefore, the pressure difference between ΔPiL and ΔPdH is
It is set larger than the fluctuation range of the differential pressure caused by the increase and stop of the platform.

Further, when the number of installed pumps is small and the pressure difference between ΔPiL and ΔPdH is set to be larger than the fluctuation range of the differential pressure generated by increasing or stopping one pump as described above, the number of operating machines increases or decreases. Differential pressure area (dead zone)
May become too wide. In this case, for example, the increment / decrement counter 705 is provided with a function of adjusting the flow rate of one of the pumps, and when the detected differential pressure exceeds ΔPdH (or falls below ΔPiL), the pump is first The discharge amount may be controlled to lower (or increase) the differential pressure, and when the control cannot be completed with that, other pumps may be stopped (or started).

There are various methods for increasing or decreasing the number of pumps to be operated according to the number of counters. In this embodiment, the number of bits corresponding to the number of pumps is preset in correspondence with the number read from the counter. A signal having "1" of each bit is set to correspond to power-on and 0 corresponds to power-off. For example, when the number of pumps is 3 and the number of counters is 2, the control signal output unit outputs the signal 011. Receiving this signal, each pump knows the digit of the signal destined for itself, and if it is 1, the start operation is started (if it is already in operation, nothing is done). , If it is 0, the operation is stopped. It is of course possible to send the 011 signal separately to each pump instead of sending it to all pumps in the same way.

According to this embodiment, stable operation can be maintained even if the permissible range of fluctuation of the pipe differential pressure when the number of operating pumps is increased or decreased is narrowed. It is difficult to be affected by the instantaneous fluctuation of the differential pressure because it is carried out in 1. At the start of operation of the device, the pumps are started one by one, so the inrush current of the pump motor is dispersed over time. The effect is that only two comparators were needed.

[0022]

According to the present invention, the differential pressure in the piping system is detected at a predetermined sampling interval, and when the detected differential pressure is lower than the first set pressure, the number of operating pumps is increased by one. , When the detected differential pressure is higher than the second set pressure, the number of operating pumps is reduced by one, so even if the number of operating pumps changes due to load fluctuations, the differential pressure applied to the load is reduced. It is possible to maintain the pressure between the first and second set pressures, and it is possible to reduce the fluctuation range of the differential pressure due to the fluctuation of the load.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main configuration of an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the concept of differential pressure control in the embodiment shown in FIG.

FIG. 3 is a conceptual diagram showing an example of sampling intervals in the embodiment shown in FIG.

FIG. 4 is a system diagram showing an example of a piping system to which the present invention is applied.

FIG. 5 is an explanatory diagram showing a conceptual example of differential pressure control in the related art.

FIG. 6 is a block diagram showing a configuration example of a pump controller in a conventional technique.

FIG. 7 is a conceptual diagram showing an example of HQ characteristics of a general pump.

[Explanation of symbols]

1 heat source machine 2A, 2B, 2C air conditioning unit 3A, 3B,
3C stop valve 5A, 5B, 5C check valve 6A, 6B,
6C pump 7 pump controller 8A, 8B,
8C Piping system 9 Differential pressure gauge 701 Increasing comparator 702 Decreasing comparator 703 1st
AND circuit 704 Second AND circuit 705 Increment / decrement counter 706 Astable multivibrator 707 Operation switch 708 Control signal output unit

Claims (2)

[Claims] 1. A plurality of pumps for pumping a fluid, a first piping system connected to the plurality of pumps for carrying the fluid to a plurality of loads, and a plurality of the fluids passing through the plurality of loads. A plurality of pumps of a piping device including a second piping system that circulates through the pump and a differential pressure detection unit that detects a pressure difference between the fluids flowing through the first and second piping systems. In a pump controller that controls the start and stop based on the output of the pressure detecting means, when the output value of the differential pressure detecting means is compared with a first set value at a predetermined sampling interval, and the output value of the differential pressure detecting means is small. And a second set value larger than the first set value at the predetermined sampling interval to compare the output value of the differential pressure detecting means with the second set value which outputs a signal to the differential pressure detecting means. Signal when the output value of Second comparing means for applying force, and the first
And a counter for increasing the set value by 1 when a signal is output from the comparing means, and decreasing the set value by 1 when the signal is output from the second comparing means, and a preset value for the set value of the counter. A pump controller, comprising control signal output means for outputting a signal for operating the pump corresponding to the number read out at intervals. 2. A pump controller for controlling start / stop of the pump of a cooling / heating system, wherein a heat medium heated and / or cooled by a heat source device is conveyed to a plurality of air conditioners by a plurality of pumps, the outlet header of the pump and the heat source device. Differential pressure detector that detects the differential pressure with the inlet header of the engine, a comparator that outputs a signal to increase the number of pumps that operate using the differential pressure value as an input, and a pump that operates using the differential pressure value as an input To output a signal for reducing one by one, an astable multivibrator that periodically generates a signal for validating the outputs of the two comparators, and a signal output from the two comparators. A pump controller that includes an increment / decrement counter that increases / decreases the number of pumps that are operating with a signal as an input.