JP3933616B2 - Variable speed water supply system - Google Patents

Description

  The present invention relates to a variable speed water supply apparatus, and more particularly to a so-called direct connection type variable speed water supply apparatus that is directly connected from a distribution pipe to a terminal water supply apparatus via a pressure pump.

  FIG. 1 shows a system outline of a direct connection type variable speed water supply apparatus. For example, an inflow pipe 12 is connected to a water distribution pipe 11 that is a main pipe of a water supply, and a pressurizing pump 13 is connected to the inflow pipe. A water meter 15 and an inflow side pressure tank 16 are connected to the inflow pipe 12. A discharge pipe 18 connected to the terminal water supply device 17 is connected to the discharge side of the pressurizing pump 13. A flow switch 19, a discharge side pressure tank 20, and the like are connected to the discharge pipe 18.

  The flow switch 19 is a switch for detecting a flow rate, and performs a so-called small water amount stop operation for stopping the pump operation in order to prevent the pump from shutting down when it is detected that the amount of water is particularly small. An inflow pressure detector 21 is connected to the inflow side of the pressurization pump 13, detects the pressure on the inflow side of the pressurization pump 13, and sends the signal to the control unit 22. Similarly, a discharge pressure detector 23 is provided on the discharge side of the pressurizing pump 13 and sends a pressure signal on the discharge side to the control unit 22.

The pump 13 is driven at a variable speed by an electric motor 25 (variable speed means) provided with a frequency / voltage converter (inverter) connected to a three-phase 200V commercial power source.
Based on the signals from the inflow pressure detector 21 and the discharge pressure detector 23, the control unit 22 sends a signal to the variable speed means 25 to control the speed of the pump 13 to be accelerated or decelerated to an arbitrary speed.

  According to JP-A-5-118280, JP-A-5-263444, JP-A-5-240186, etc., by maintaining the pressure on the discharge side of the pressurizing pump constant, a predetermined pressure is applied to the terminal water supply device. A technique for increasing or decreasing the speed of a pump so that a constant amount of water can be supplied is disclosed. In addition, when the pressure on the inflow side of the pump is reduced, the pressure on the side of the water distribution pipe is prevented from being reduced by slowing or stopping the pump when the pressure on the inflow side of the pump is reduced so that the water pressure does not decrease in the water distribution pipe. Etc. are disclosed.

  In such a direct-coupled variable speed water supply system, a water storage tank is connected to a conventional water distribution pipe, and water stored in the water storage tank is distributed to a terminal water supply device using a pressurizing pump. There are benefits. The merit is that no water storage tank is provided, so that the water supply apparatus can be downsized as a whole and the installation area can be reduced. Since water is not stored, it is preferable in terms of hygiene. Since the water pressure in the water distribution pipe can be used as it is on the suction side of the pressurizing pump, the head of the pressurizing pump is lowered, and energy saving can be achieved accordingly.

  However, in the conventional water supply device before the direct connection type, the water storage tank is provided, so that the pressure pump inflow side is maintained at almost zero pressure, and the pump inflow side pressure rises as in the direct connection type. There wasn't. The parameters used for the operation control of the conventional variable speed water supply apparatus have been accumulated by many experiences, which are determined when such a water storage apparatus is provided and the inflow pressure is almost zero. However, in the direct connection type variable speed water supply apparatus, since the pressure on the inflow side is always influenced by the water pressure in the water distribution pipe, there are various inconveniences when the operation control parameters of the conventional pump are used as they are.

  For example, the flow rate detector detects that the amount of water is small, and once the pump is operating at a relatively high operating speed for a certain period of time to accumulate pressure in the pressure tank, the pump stops the pump. There is a case. Conventionally, when the pressure accumulation operation is performed in the tank, the operation speed of the pump is determined on the assumption that the inflow side pressure is almost zero. However, if the inflow pressure of the pump fluctuates as in a direct-coupled water supply device, if the operation speed of the pump that accumulates pressure in the tank is based on the premise that the inflow pressure is zero, the discharge is equivalent to the inflow pressure of the pump. There was a problem that the accumulated pressure increased because the pressure increased.

  In addition, in the variable speed water supply apparatus including two pumps that can be operated in parallel, when one pump cannot supply the water amount, another spare pump is additionally supplied to operate in parallel. The timing of this additional charging is when the operation speed reaches the rated speed of the pump when the inflow pressure is zero while operating at a constant discharge pressure, and the pump becomes overloaded when the inflow pressure increases. There is a problem. This is because the operating point shifts to the large water amount side in order to achieve the set discharge pressure rated operation speed from the pump head characteristics.

  Further, when the inflow pressure becomes high or the load water amount decreases while the two pumps are operating in parallel, one pump needs to be disconnected in order to be in time. Assuming that the disconnection timing is a certain operation speed when the inflow pressure is zero, there is a problem that an inching operation to be added immediately occurs when the inflow pressure fluctuates. Further, when the inflow pressure is lowered, the water volume to be disconnected changes to the small water volume side. Therefore, there is a case where the amount of water that can be operated by one unit is continued without being disconnected, and two units are continuously operated, which is a waste of energy. Further, the amount of water to be disconnected further changes to the small amount of water, and there is a problem that the pump is heated by the shutoff operation without disconnecting even when the amount of water is zero.

  The present invention has been made in view of the above-described circumstances, and provides a variable speed water supply apparatus capable of performing a stable operation even when the inflow pressure of the pump fluctuates in a direct connection type variable speed water supply apparatus. Objective.

In order to achieve the above-described object, the first aspect of the present invention includes an inflow pipe connected to a water distribution pipe, a plurality of pressurization pumps connected to the inflow pipe, and a discharge side of the pressurization pump. A discharge pipe, an inflow pressure detector for detecting an inflow pressure of a pressurization pump provided in the inflow pipe, a discharge pressure detector for detecting a discharge pressure of a pressurization pump provided in the discharge pipe, a variable speed drive means for variable speed drives the pressure pump, and a control means for controlling the pump, the control means, the pressure using a pump inlet pressure detected by the inlet pressure detector It is characterized in that the set speed for the additional charging of the pump and the operation speed of the pump operated at a fixed speed after the addition of the pump are corrected .
A second aspect of the present invention includes an inflow pipe connected to a water distribution pipe, a plurality of pressure pumps connected to the inflow pipe, a discharge pipe connected to a discharge side of the pressurization pump, and the inflow An inflow pressure detector for detecting an inflow pressure of a pressurization pump provided in a pipe, a discharge pressure detector for detecting a discharge pressure of a pressurization pump provided in the discharge pipe, and a variable speed drive of the pressurization pump Variable speed drive means for controlling the pump and control means for controlling the pump, wherein the control means uses a pump inflow pressure detected by the inflow pressure detector for one pump in the parallel operation of two pumps. The fixed speed is fixed, and when the operating speed of the other pump operated at a variable speed reaches the set speed corrected by using the pump inflow pressure, the disconnection is released.
According to one aspect of the present invention, a pressure tank is connected to the discharge pipe.
According to one aspect of the present invention, the control means stops the pressurizing pump when the pump inflow pressure detected by the inflow pressure detector becomes equal to or lower than a set pressure.
According to one aspect of the present invention, the control means is disconnected when the pump that is operated at a variable speed in parallel operation is in a low water amount state.

  A preferred embodiment of the present invention includes an inflow pipe connected to a water distribution pipe, a pressurization pump connected to the inflow pipe, a discharge pipe connected to a discharge side of the pressurization pump and connected to a terminal water supply device. An inflow pressure detector for detecting an inflow pressure of a pressurization pump provided in the inflow pipe, a discharge pressure detector for detecting a discharge pressure of a pressurization pump provided in the discharge pipe, and the pressurization pump. Variable speed driving means for variable speed driving and control means for controlling the pump, the control means depending on the pump inflow pressure detected by the inflow pressure detector as a parameter for controlling the operation of the pump. And control the operation based on the corrected parameter.

The correction of the parameter according to the pump inflow pressure is performed by a relational expression between an arbitrary operation speed V of the pump and the shutoff pressure Po when the inflow pressure value is zero.
Po = F (V)
The parameter Vn for controlling the operation of the pump when the inflow pressure value is zero is expressed in accordance with the inflow pressure Ps.
Vn '= ((F (Vn) -Ps) / F (Vn)) ^1/2 * Vn
It was corrected with.

  The corrected parameter Vn ′ for controlling the operation of the pump is used for the control when the pump is stopped at a small amount of water. If the flow rate detector detects that the amount of water is small, the inflow The operation speed Vn at the time of accumulating a small amount of water when the pressure value is zero is pressurized for a certain time at a speed Vn 'corrected according to the above equation.

  Further, the corrected parameter Vn ′ for controlling the operation of the pump is obtained when the second pump is additionally supplied with respect to the one operating pump when the two pumps are operated in parallel. If the set speed Vn for pump addition when the inflow pressure value is zero reaches the speed Vn ′ corrected according to the above equation, the second pump is additionally charged.

  The corrected parameter Vn ′ for controlling the operation of the pump is a pump in which the two pumps are operating in parallel and the inflow pressure value is zero when one of the pumps is disconnected. The set-off speed Vn is set at a speed Vn ′ corrected according to the above equation.

  Since the pump operation control parameter when the inflow pressure is zero is corrected according to the pump inflow pressure detected by the inflow pressure detector, and the operation control is performed based on the corrected parameter, the direct connection type In the variable speed water supply apparatus, even if the inflow pressure of the pump fluctuates, operation control can be performed under appropriate parameters.

In general, the pump cutoff pressure is proportional to the square of the rotational speed of the pump. Therefore, the relational expression between the pump operating speed V and the cutoff pressure Po.
Po = F (V)
The parameter Vn that controls the operation of the pump when the inflow pressure value is zero is
Vn '= ((F (Vn) -Ps) / F (Vn)) ^1/2 * Vn
In this way, it is possible to operate with the corrected parameter Vn 'when the inflow pressure Ps is present.

  Since the pressure accumulating operation speed Vn at the time of stopping the small amount of water is operated at the speed Vn ′ corrected according to the above formula, it is possible to prevent the discharge side pressure from being extremely increased.

  When performing parallel operation of two pumps, when adding the second pump to the one pump in operation, the operating speed Vn 'used for the additional injection is taken into account the inflow pressure. Since the correction is performed based on the equation, the second pump can be additionally charged under an appropriate load. This avoids overloading of the pump.

  Two pumps are operating in parallel, and when one of them is disconnected, the set speed Vn of the pump disconnection when the inflow pressure value is zero is solved by the speed Vn 'corrected by the above equation. By performing the row, the inching operation of the pump and the like can be prevented, and the appropriate pump can be disconnected.

  ADVANTAGE OF THE INVENTION According to this invention, even if the inflow pressure of a pump fluctuates in a direct connection type variable speed water supply apparatus, stable operation | movement can be performed. That is, even if the inflow pressure rises, an appropriate operation can be performed by the correction, an excessive increase in water pressure to the terminal water supply device can be prevented, and the energy saving operation of the pump can be performed.

  Hereinafter, embodiments and examples of the present invention will be described with reference to the accompanying drawings.

  Also in this invention, the pressurization pump 13 is directly connected to the water distribution pipe 11, and the system configuration | structure which directly connects water supply to the terminal water supply apparatus 17 without going through a water tank from the water distribution pipe 11 is as showing in FIG. The pressurizing pump 13 performs discharge pressure control to increase / decrease the pump rotation speed by the variable speed means 25 such as an inverter so that the supply water pressure to the terminal water supply device 17 becomes constant by the signal of the discharge pressure detector 23. . In addition, when the inflow pressure is reduced, the inflow pressure control is performed so that the variable speed means 25 reduces or stops the pump rotation speed when the inflow pressure falls below a certain inflow set pressure value so as not to adversely affect the water distribution pipe. Is called. The discharge pressure control is switched to the inflow pressure control when the inflow pressure Ps becomes equal to or lower than the selected set pressure.

FIG. 2 shows the configuration of the control portion of the variable speed water supply apparatus of the present invention. The pressure Ps on the inflow side of the pressurization pump 13 is input from the inflow pressure detector 21 to the control unit 22, and the pressure Pd on the discharge side of the pressurization pump 13 is input from the discharge pressure detector 23. The set pressure P1 is a control target value of the discharge pressure, and is normally set to 196 to 294 kPa ( ^{2 to 3} kg / cm ² ). The set pressure P2 is a control target value of the inflow pressure Ps, and this target set pressure is normally set to about 98 kPa (1 kg / cm ² ) so as not to adversely affect the water distribution pipe. The set pressure P3 is a set pressure value for selecting the inflow pressure control and the discharge pressure control. When the inflow pressure Ps of the inflow pressure detector is lowered and the distribution pipe may be adversely affected, the discharge pressure is controlled. This is for switching from control to inflow pressure control. The control unit 22 gives a speed command for accelerating or decelerating the pump 13 to the variable speed driving means (inverter) 25 according to the values of the inflow pressure Ps and the discharge pressure Pd.

  Various parameters for controlling the operation of the pump are input to the control unit 22. This is the operation speed at the time of pressure accumulation in the operation of stopping a small amount of water, the operation speed at the time of additional charging for parallel operation of two pumps, the operation speed at the time of releasing one unit from the parallel operation of two pumps, and the like. As these operation speeds, the operation speed when the inflow pressure value is zero is input.

FIG. 3 shows a block diagram of the control unit of one embodiment of the present invention. Operation control is performed while correcting a parameter relating to pump operation control when the inflow pressure is zero, for example, an operation speed Vn, to a pump operation speed Vn ′ required after the pump receives the inflow pressure Ps. In other words, the control unit 22 includes a calculation device 31 for the cutoff pressure. The calculation device 31 of the cutoff pressure stores a relational expression between an arbitrary operation speed V of the pump and the cutoff pressure when the inflow pressure value is zero based on the unique characteristics of each pump, and for the operation speed Vn of the pump, Calculate the deadline pressure Po. This relation
Po = F (Vn)
May be a subroutine that stores the deadline pressure Po corresponding to the actual speed Vn in a storage device and returns Po with an arbitrary speed Vn as an unknown, and has a formula that approximates the relationship between the two. May be.

Next, the control unit 22 includes a calculation device 32 that performs a calculation for correcting the parameter based on the calculation result F (Vn) of the cutoff pressure and the inflow pressure Ps. This speed correction formula is
Vn '= ((F (Vn) -Ps) / F (Vn)) ^1/2 * Vn
It is. In general, in a pump, the cutoff pressure is proportional to the square of the pump rotational speed.
Therefore, the operating speed Vn 'is obtained as a correction value at the inflow pressure Ps by multiplying the square root of the ratio of the difference between the deadline pressure F (Vn) and the inflow pressure Ps by the operation speed Vn when the inflow pressure value is zero. be able to. By performing pump operation control at this corrected speed Vn ', it is possible to perform appropriate pump operation control by correction according to the inflow pressure Ps using various parameters when the inflow pressure is zero. it can.

When the speed of the pump is controlled at a constant discharge pressure, water is no longer used on the terminal water supply device side, and the pump is shut off when the amount of water becomes almost zero. If the pump shut-off operation is continued, the pump generates heat and needs to be stopped, so that a so-called small water amount stop operation is started. The condition for restarting the pump is when the discharge pressure falls below the target discharge pressure, but if the pump is stopped as it is when a small amount of water is detected, the discharge pressure immediately falls below the target discharge pressure and the pump starts and stops frequently. Will be repeated. For this reason, if it is detected that the amount of water is small, the pump rotation speed is increased immediately before stopping the pump, and the pump is stopped after accumulating in the discharge side pressure tank at a pressure slightly higher than the target discharge pressure. . In this way, even if water is used a little, it takes time for the pressure to drop to the target discharge pressure, so that the pump stop time can be increased.
If the operating speed at the time of pressure accumulation is too high at this time, the pressure fluctuation on the terminal water supply device side will increase, so if the operating speed set at the time when the inflow pressure is almost zero, the inflow pressure will be directly connected In this case, there is a possibility that an extremely large pressure is applied to the terminal water supply device.

FIG. 4 shows a flow of a small water amount stop operation. If a small amount of water is detected, the deadline pressure Po is calculated. This calculates the shut-off pressure Po corresponding to the pressure accumulation operation speed Vn at the time of stopping the small amount of water when the inflow pressure is zero from the characteristic of the pump. Then, the inflow pressure Ps is read. Then, the operation speed Vn ′ during the pressure accumulation operation corrected by the inflow pressure Ps is calculated by the equation of the arithmetic unit 32,
Vn '= ((F (Vn) -Ps) / F (Vn)) ^1/2 * Vn
Based on. Then, the pressure accumulation operation is performed for a predetermined time at the obtained operation speed Vn ′. When the pressure accumulation operation is finished, the pump is stopped.

  As described above, in the present invention, in the operation of stopping the small amount of water, the operation speed Vn at the time of accumulating is corrected appropriately according to the inflow pressure Ps and lowered to Vn ′. There is no problem that the discharge pressure becomes extremely high.

  The operating speed at the time of additional charging means that when two pumps are operated in parallel, the operating speed gradually increases when the load water volume increases for one operating pump, and the rated speed When it reaches, add the second pump. The speed at that time is zero, that is, when the inflow pressure value is zero, that is, when the water storage tank in the prior art is provided, the set speed for adding the pump is Vn.

FIG. 5 shows a control flow for additional charging of the second pump.
First, the operation speed Vn of the pump is read. This Vn is the speed at which the second pump is additionally charged when the inflow pressure is zero. The cutoff pressure Po corresponding to the operating speed Vn when the inflow pressure is zero is calculated. Then, the inflow pressure Ps is read. The operation speed Vn ′ at the time of additional charging corrected by the inflow pressure Ps is calculated by the equation of the arithmetic unit 32,
Vn '= ((F (Vn) -Ps) / F (Vn)) ^1/2 * Vn
Based on. When the first pump reaches the determined operating speed Vn ′, the second pump is additionally charged.

  As described above, in the present invention, when the second pump is additionally charged, the operation speed Vn is appropriately corrected according to the inflow pressure Ps to obtain Vn ′. Therefore, even if the inflow pressure Ps increases, the pump is overloaded. Does not cause the problem of becoming.

  The operating speed Vn at the time of disconnection is the speed when two pumps are operating in parallel as described above and one of them is disconnected. Vn is a set speed at the time of disconnection from the pump when the inflow pressure value is zero, that is, when a water storage tank in the prior art is provided.

FIG. 6 shows a control flow for releasing one unit from the pump when two units are operating.
First, the pump operating speed Vn is read. This Vn is the speed at which the pump is disconnected when the inflow pressure is zero. Then, the deadline pressure Po corresponding to the operation speed Vn for disconnecting one pump when the inflow pressure is zero is calculated. Then, the inflow pressure Ps is read. Then, the operation speed Vn ′ at the time of the parallel operation corrected by the inflow pressure Ps is calculated by the equation of the arithmetic unit 32,
Vn '= ((F (Vn) -Ps) / F (Vn)) ^1/2 * Vn
Based on. When the calculated operating speed Vn ′ is reached, one of the two pumps in parallel operation is disconnected and disconnected.

  As described above, in the present invention, when one of the two pumps operated in parallel is disconnected, the operating speed Vn is appropriately corrected according to the inflow pressure Ps to obtain Vn '. Therefore, the inflow pressure Ps varies. However, inconveniences such as inching operations that frequently occur addition and disconnection do not occur.

Next, the addition / disconnection operation of one embodiment of the present invention will be described.
When the flow rate of the pump at the time of one unit operation is “open” (water is flowing) and the operation speed reaches the maximum pump speed Vn ′ (max) and continues for 3 seconds, the second pump Perform additional loading. Here, the maximum speed Vn ′ (max) of the first pump is the maximum speed Vn (max) when the inflow pressure is zero and the inflow pressure Ps at the time of switching.
Vn ′ (max) = ((F (Vn (max)) − Ps) / F (Vn (max))) ^1/2
× Vn (max)
It is converted by the calculation.

When the second pump is additionally supplied, the first pump is fixed at 95% of the maximum speed (for example, 57 Hz when the maximum speed is 60 Hz), and the second pump is operated at a variable speed.
Here, the speed Vn ′ (95%) of 95% is the maximum speed Vn (95%) when the inflow pressure is zero and the inflow pressure Ps at the time of switching.
Vn ′ (95%) = ((F (Vn (95%)) − Ps) / F (Vn (95%))) ^1/2
× Vn (95%)
It is converted by the calculation.

When the amount of water used further increases and the operating speed of the second pump reaches the maximum speed Vn ′ (max), the first pump and the second pump are switched to a uniform speed operation that operates at the same speed. Here, the maximum speed Vn ′ (max) of the second pump is relative to the maximum speed Vn (max) when the inflow pressure is zero and the inflow pressure Ps at the time of switching.
Vn ′ (max) = ((F (Vn (max)) − Ps) / F (Vn (max))) ^1/2
× Vn (max)
It is converted by the calculation.

After that, if the amount of water used decreases and the operation speed during uniform speed operation reaches 92% of the maximum speed (for example, 55 Hz when the maximum speed is 60 Hz), the operation speed of the first pump is set to 95%. Fixed, the second pump is variable speed operation.
Here, the 95% speed Vn ′ (95%) is 95% speed Vn (95%) when the inflow pressure is zero and the inflow pressure Ps at the time of switching.
Vn ′ (95%) = ((F (Vn (95%)) − Ps) / F (Vn (95%))) ^1/2
× Vn (95%)
It is converted by the calculation.

Further water consumption is reduced flow switch a Second pumps for variable speed operation is "closed" (low water volume state), if the condition has passed for three seconds, the second unit pump is Kairetsu disengaged The first pump is operated at a variable speed.

  The addition / disconnection operation of the second pump described above is only one embodiment to which the present invention is applied. It goes without saying that various modifications can be made without departing from the spirit of the present invention in a so-called direct-coupled water supply apparatus including two variable speed pumps.

Explanatory drawing of the system configuration | structure of a direct connection type variable speed water supply apparatus. Explanatory drawing of the control system of the variable speed water supply apparatus of one Example of this invention. The block diagram of the parameter correction of one Example of this invention. The flowchart of the small water amount stop operation | movement of one Example of this invention. FIG. 4 is a flow chart of additional charging of pump parallel operation according to an embodiment of the present invention. FIG. 3 is a flow chart of disconnection and separation of the pump parallel operation according to the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Distribution pipe 12 Inflow pipe 13 Pressurization pump 15 Metering water device 16 Inflow side pressure tank 17 Terminal water supply equipment 18 Discharge pipe 19 Flow switch 20 Discharge side pressure tank 21 Inflow pressure detector 22 Control part 23 Discharge pressure detector 25 Variable speed Means (inverter)
31 Calculation section for calculating deadline pressure Po 32 Calculation section for operating speed correction Ps Inflow pressure Pd Discharge pressure

Claims (5)

An inflow pipe connected to the water pipe;
A plurality of pressure pumps connected to the inflow pipe;
A discharge pipe connected to the discharge side of the pressure pump;
An inflow pressure detector for detecting an inflow pressure of a pressurizing pump provided in the inflow pipe;
A discharge pressure detector for detecting a discharge pressure of a pressure pump provided in the discharge pipe;
Variable speed drive means for driving the pressure pump at a variable speed;
Control means for controlling the pump,
Control means, to correct the operating speed of the pump to be operated by the inflow pressure detector at a fixed speed of the rear set speed and pump additional add-on of the pressure pump with a pump inlet pressure detected A variable speed water supply device characterized by An inflow pipe connected to the water pipe;
A plurality of pressure pumps connected to the inflow pipe;
A discharge pipe connected to the discharge side of the pressure pump;
An inflow pressure detector for detecting an inflow pressure of a pressurizing pump provided in the inflow pipe;
A discharge pressure detector for detecting a discharge pressure of a pressure pump provided in the discharge pipe;
Variable speed drive means for driving the pressure pump at a variable speed;
Control means for controlling the pump,
The control means fixes one pump at a speed corrected by using the pump inflow pressure detected by the inflow pressure detector when two pumps are operated in parallel, and another pump operated at a variable speed. The variable speed water supply apparatus is characterized in that when the operating speed becomes a set speed corrected using the pump inflow pressure, the disconnection is released. The variable speed water supply apparatus according to claim 1, wherein a pressure tank is connected to the discharge pipe. Wherein, variable speed according to any one of claims 1 to 3, characterized in that the inflow pressure detector pump inlet pressure detected by stops the pressurization pump and falls below the set pressure Water supply device. 2. The variable speed water supply apparatus according to claim 1, wherein the control unit is disconnected when the pump operated at a variable speed in parallel operation is in a low water amount state.

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