JP2020134326A - Flow rate estimation method for liquid pump equipment, liquid pump equipment - Google Patents

Abstract

A flow rate estimation method for a liquid pump device and a liquid pump device capable of estimating a flow rate with little error from the actual flow rate are provided. A method for estimating a flow rate of a liquid pump device (1) includes: a liquid pump device (1) having a pump body (3) driven by an inverter (2); The relationship between the pump head, which is the difference from the pressure, and the flow rate of the liquid discharged from the pump main body 3 is stored in advance by actually measuring the flow rate with respect to a plurality of operating frequencies and a plurality of pump head heights. The flow rate at the operating frequency and the pump head obtained during the operation of is estimated based on the stored relationship between the operating frequency, the pump head, and the flow rate. [Selection drawing] Fig. 1

Description

An embodiment of the present invention relates to a method for estimating a flow rate of a liquid pump device and a liquid pump device.

For example, a liquid pump device used for supplying water used by a heat source machine is generally used together with a flow meter for measuring the flow rate of water discharged from the liquid pump device. However, the installation position of the flowmeter may be limited, for example, it must be installed in a straight pipe. In addition, although the flow meter depends on the specifications, correct measurement may not be possible if air bubbles are present in the liquid or the piping is rusted.

Therefore, for example, Patent Document 1 proposes to measure the flow rate of water discharged from a pump based on PQ characteristics without using a flow meter. The PQ characteristic indicates the relationship between the differential pressure (P) on the outlet side and the inlet side of the pump and the flow rate (Q) at the differential pressure, and generally, the inverter is driven at the rated frequency. It is provided by the pump manufacturer as a characteristic of the case.

Japanese Unexamined Patent Publication No. 2008-241326

However, the PQ characteristics of the actual pump depend on the rotation speed of the pump, not the operating frequency of the inverter, and the rotation speed of the pump also changes due to so-called motor slippage or the like. Therefore, if the flow rate is estimated based on the PQ characteristic at the rated frequency, an error will occur between the flow rate and the actual flow rate.

Therefore, we provide a flow rate estimation method for a liquid pump device and a liquid pump device that can estimate the flow rate with little error from the actual flow rate.

In the flow rate estimation method of the liquid pump device of the embodiment, in a liquid pump device including a pump body driven by an inverter, the pump is the difference between the operating frequency of the pump body and the pressure on the discharge side and the pressure on the suction side of the pump body. The relationship between the lift and the flow rate of the liquid discharged from the pump body is stored in advance by actually measuring the flow rates for a plurality of operating frequencies and a plurality of pump lifts, and the operating frequency acquired during actual operation is used. The flow rate at the pump head is estimated based on the relationship between the stored operating frequency, the pump head, and the flow rate.

The figure which shows typically the structure of the liquid pump device The figure which shows the flow of the process which finds the relationship between an operating frequency, a pump head, and a flow rate. Diagram showing the relationship between operating frequency, pump head and flow rate as a data table The figure which shows the flow of the process which calculates the flow rate at the time of the actual operation Diagram showing the relationship between operating frequency, pump head and flow rate as a function

Hereinafter, embodiments will be described with reference to FIGS. 1 to 3.
As shown in FIG. 1, the liquid pump device 1 is discharged from a pump body 3 driven by an inverter 2, a suction pressure sensor 4 that detects a suction pressure which is the pressure of the liquid sucked into the pump body 3, and a pump body 3. It is provided with a discharge pressure sensor 5, a control unit 6, a storage unit 7, and the like for detecting the discharge pressure, which is the pressure of the liquid. Hereinafter, the side on which the liquid is sucked into the pump body 3 is referred to as a suction side, and the side on which the liquid is discharged from the pump body 3 is referred to as a discharge side.

The pump body 3 sends a liquid, and in the present embodiment, water is assumed as the liquid. If the pump body 3 is to send a liquid, the structure, type, or capacity of the pump body 3 may be appropriately selected according to the required specifications. The inverter 2 drives the pump body 3 by generating and outputting, for example, a PWM control signal based on a control command from the control unit 6. Since the inverter 2 may have a well-known configuration, detailed description thereof will be omitted.

In the case of this embodiment, the suction pressure sensor 4 is provided in the suction pipe 8 provided on the suction side of the pump main body 3, and the pressure of the liquid flowing through the suction pipe 8, that is, the liquid sucked into the pump main body 3. Detect pressure. The suction pipe 8 is a portion supplied as a part of the liquid pump device 1. That is, the suction pressure sensor 4 is provided at a portion supplied from the manufacturer as a part of the liquid pump device 1, and constitutes a pressure sensor capable of acquiring the pump head.

An external pipe is connected to the suction pipe 8 via a suction side valve 9. Hereinafter, the pipe connected to the suction pipe 8 will be referred to as an inlet pipe 10. The inlet pipe 10 is connected to a water tank (not shown).

In the case of this embodiment, the discharge pressure sensor 5 is provided in the discharge pipe 11 provided on the discharge side of the pump body 3. The discharge pressure sensor 5 detects the pressure of the liquid flowing through the discharge pipe 11, that is, the pressure of the liquid discharged from the pump body 3. The discharge pipe 11 is a portion supplied as a part of the liquid pump device 1. That is, the discharge pressure sensor 5 is provided at a portion supplied from the manufacturer as a part of the liquid pump device 1, and constitutes a pressure sensor capable of acquiring the pump head.

Further, an external pipe is connected to the discharge pipe 11 via a discharge side valve 12. Hereinafter, the pipe connected to the discharge pipe 11 will be referred to as an outlet pipe 13. The outlet pipe 13 connects the liquid pump device 1 and an external device such as a heat source machine 14 called a so-called chiller, for example. That is, it is assumed that the liquid pump device 1 of the present embodiment is used to supply water for use by the heat source machine 14. Although the required minimum flow rate is generally specified, the heat source machine 14 does not necessarily require strict adjustment of the flow rate, and can operate normally if water of the minimum flow rate or higher is supplied. It is a device that can be used.

The control unit 6 is composed of, for example, a microcomputer, and controls the liquid pump device 1 based on the water pressure and temperature detected by the suction pressure sensor 4, the discharge pressure sensor 5, the temperature sensor 15, and the like. In this embodiment, the control unit 6 generates a control command for driving the pump main body 3 based on the flow rate command value given from the upper control device 16 and outputs the control command to the inverter 2. Further, although the details will be described later, the control unit 6 also has a function as an estimation unit for estimating the flow rate of water discharged from the pump body 3 in the liquid pump device 1 not provided with a flow meter.

The storage unit 7 stores various data necessary for the operation of the liquid pump device 1, such as a computer program executed by the control unit 6. Further, although the details will be described later, the storage unit 7 has a relationship between the operating frequency of the inverter 2, the pump head which is the difference between the discharge pressure and the suction pressure, and the flow rate of the liquid discharged from the pump body 3. It is stored in advance by actually measuring the flow rate at a plurality of operating frequencies and a plurality of pump heads. The relationship between the operating frequency, the pump head, and the flow rate is acquired and stored before the liquid pump device 1 is shipped, for example, during a pre-shipment test.

Next, the operation of the above configuration will be described.
As mentioned above, pumps used for industrial purposes are generally provided with a flow meter. However, the installation position of the flowmeter is limited, for example, it must be installed in a straight pipe. In addition, although the flow meter depends on the specifications, correct measurement may not be possible if air bubbles are present in the liquid or the piping is rusted. Therefore, it is required that the flow rate can be measured sideways without providing a flow meter.

However, in the case of the pump body 3 driven by the inverter 2 as in the present embodiment, although the flow rate changes when the operating frequency of the inverter 2 changes, the actual flow rate correlates with the rotation speed, not the operating frequency. There is. That is, even if the operating frequency is the same, the flow rate also changes when the rotation speed of the pump changes. Further, the rotation speed of the pump changes due to so-called motor slippage.

Therefore, if the PQ characteristic at the rated operating frequency provided by the pump manufacturer is used, an error will occur between the estimated flow rate and the actual flow rate. The PQ characteristic indicates the relationship between the pump head (P), which is the differential pressure between the outlet side and the inlet side of the pump, and the flow rate (Q) at the pump head (P). The error becomes remarkable in a low frequency region where the operating frequency is low, or when the flow rate is small and the pump head is relatively high.

Therefore, the liquid pump device 1 of the present embodiment makes it possible to estimate the flow rate with a small error from the actual flow rate even when the flow meter is not provided as follows.

The liquid pump device 1 is tested at the time of shipment of the product, for example, and the relationship between the operating frequency, the pump head, and the flow rate in the state where the liquid pump device 1 is actually driven, more strictly speaking, a plurality of operating frequencies. And the actual flow rates at multiple pump heads are obtained. Hereinafter, the work of acquiring the relationship between the operating frequency, the pump head, and the flow rate will be referred to as data acquisition for convenience. In addition, a flow meter for measuring the flow rate shall be temporarily provided for data acquisition.

Specifically, as shown in FIG. 2, at the time of data acquisition, the operating frequency of the inverter 2 is set (S1), and the pump head is set (S2). At this time, the pump head can be set or changed by, for example, providing a valve on the discharge side of the pump body 3 and adjusting the opening / closing degree of the valve. Subsequently, the flow rate at the operating frequency and the pump head is measured (S3), and the operating frequency, the pump head and the flow rate are stored (S4).

Subsequently, it is determined whether or not the data acquisition is completed (S5). This determination is determined by whether or not the required number of data can be acquired. In the case of the present embodiment, it is said that the data acquisition is completed by measuring the flow rates at each of a plurality of preset operating frequencies and a plurality of pump heads. The respective numbers are set in the range of 20 Hz to 80 Hz, for example, separated by 10 Hz for the operating frequency, and in the range of 20 kPa to 400 kPa, for example, separated by 10 kPa for the pump head. However, the range and delimiter shown here are examples, and are not limited to this.

If the data acquisition is not completed (S5: NO), the process proceeds to step S1 to set the operating frequency, the pump head is set in step S2, and then the process of measuring the flow rate in step S3 is repeated. Although it is assumed that the process proceeds to step S1 here, when measuring the flow rates at different pump heads at the same frequency, step S1 may be omitted and the process may proceed to step S2. In this case, by gradually opening the valve on the discharge side from the fully closed state, it is possible to measure the flow rates at a plurality of pump heads at the same frequency.

Then, when all the data acquisition is completed (S5: YES), the process ends. By acquiring the data in this way, as shown in FIG. 3, matrix data M of the measured values of the flow rates at the plurality of operating frequencies and the plurality of pump heads can be obtained. That is, the relationship between the operating frequency, the pump head, and the flow rate is stored as a data table. In the table data stored at this time, the relationship between the operating frequency in the assumed operating frequency range and the assumed pump head range, the pump head, and the flow rate is stored.

That is, in FIG. 3, when the actual characteristics of the liquid pump device 1 are, for example, when the operating frequency is 10 Hz and the pump head is 20 kPa, the flow rate is HA1 (cubic meter / h), and when the operating frequency is 10 Hz and the pump head is 30 kPa. Shows that the flow rate is HA2 (cubic meter / h), and when the operating frequency is 20 Hz and the pump head is 20 kPa, the flow rate is HB1 (cubic meter / hour). It should be noted that HA1, HA2 or HB1 shown in FIG. 3 are schematic, and the numerical values are actually stored in each.

By the way, the pump head is obtained as the difference between the discharge pressure and the suction pressure. At this time, if the acquisition mode of the pump head differs between the data acquisition time and the actual operation time, an error may occur in the estimation of the flow rate. In other words, if the acquisition mode of the pump head is the same at the time of data acquisition and at the time of actual operation, it is considered that the estimated flow rate is almost the same as the actual flow rate.

Therefore, in the present embodiment, the suction pressure sensor 4 and the discharge pressure sensor 5 are provided in the suction pipe 8 and the discharge pipe 11 which are integrally supplied with the liquid pump device 1, respectively. In other words, the suction pressure sensor 4 and the discharge pressure sensor 5 can be used even when the liquid pump device 1 is installed at the site and external pipes are connected, and what kind of shape and type of external pipes are used. Even if it is a thing, it is basically provided in a part where the mounting mode such as its position, structure or shape does not change.

As a result, the acquisition mode of the pump head can be made the same at the time of data acquisition and at the time of actual operation, and more accurate flow rate estimation becomes possible. In other words, as the pump lift, the pressure of the liquid at the portion connected to the pump body 3 on the discharge side of the pump body 3 and provided as a part of the liquid pump device 1 and the suction side of the pump body 3 By using the difference from the pressure of the liquid in the portion connected to the pump body 3 and provided as a part of the liquid pump device 1, more accurate estimation of the flow rate becomes possible.

By the way, when actually operating the liquid pump device 1, the control unit 6 acquires the current operating frequency of the inverter 2 (T1) and acquires the current pump head (T2) as shown in FIG. ), The flow rate at the acquired operating frequency and pump head is estimated based on the above data table (T3). At this time, the operating frequency or the flow rate at the pump head that is not stored in the data table is estimated by linear interpolation of the values stored in the data table. For example, when the operating frequency is 15 Hz and the pump head is 20 kPa, the flow rate is estimated as (HA1 + HB1) / 2. The operating frequency of the inverter 2 is known by the control unit 6.

Then, when the operation is not completed, the control unit 6 proceeds to step T1 (T4: NO), and repeats the acquisition of the operating frequency, the acquisition of the pump head, and the estimation of the flow rate. On the other hand, the control unit 6 determines that the operation has been completed (T4: YES) when the higher-level control device 16 or the like instructs the end of the operation, and ends the process. After that, when the control unit 6 finishes estimating the flow rate, the control unit 6 controls the operating state of the inverter based on the estimated flow rate. The estimated flow rate is basically used for control in the liquid pump device 1 except in the case of an abnormality.

In this way, the liquid pump device 1 estimates the flow rate based on the relationship between the operating frequency, the pump head, and the flow rate actually measured in advance, without using a flow meter, with little error from the actual flow rate.

According to the configuration described above, the following effects can be obtained.
In the flow rate estimation method of the liquid pump device 1, in the liquid pump device 1 including the pump main body 3 driven by the inverter 2, the difference between the operating frequency of the inverter 2 and the pressure on the discharge side and the pressure on the suction side of the pump main body 3 The relationship between the pump head and the flow rate of the liquid discharged from the pump main body 3 is memorized by actually measuring the flow rates for a plurality of operating frequencies and a plurality of pump heads in advance, and the memorized operation. Based on the relationship between frequency, pump head, and flow rate, the flow rate at the operating frequency and pump head acquired during actual operation is estimated.

With such a configuration, the flow rate estimated based on the relationship between the stored operating frequency, the pump head, and the flow rate is in line with the actual operating state of the liquid pump device 1, that is, the pump. The number of rotations and the slip of the motor are taken into consideration. Therefore, the flow rate can be estimated with little error from the actual flow rate without using a flow meter.

Further, in the flow rate estimation method of the liquid pump device 1, the pump head is obtained as the difference between the pressure detected by the discharge pressure sensor 5 and the pressure detected by the suction pressure sensor 4. At this time, the discharge pressure sensor 5 detects the pressure of the liquid on the discharge side of the pump main body 3 at a portion connected to the pump main body 3 and provided as a part of the liquid pump device 1. Further, the suction pressure sensor 4 detects the pressure of the liquid at the portion connected to the pump body 3 on the suction side of the pump body 3 and provided as a part of the liquid pump device 1.

With such a configuration, the pump head acquisition mode can be the same at the time of data acquisition and at the time of actual operation, and the flow rate can be estimated more accurately.

Further, in the flow rate estimation method of the liquid pump device 1, the relationship between the operating frequency, the pump head and the flow rate is stored as a data table, and the actual operating frequency and the flow rate at the pump head can be obtained by using the data table or. The data table is estimated by linear interpolation in this embodiment.

With such a configuration, the number of data in the data table to be prepared in advance can be reduced. In addition, the amount of calculation when estimating the flow rate during actual operation can be reduced. Further, since the stored table data stores the relationship between the expected operating frequency range and the operating frequency, the pump head, and the flow rate in the assumed pump head range, the liquid pump device 1 Even if the operating state changes, the flow rate can be estimated accurately by following the change.

Further, the liquid pump device 1 includes a pump main body 3 driven by the inverter 2 and a pressure sensor capable of acquiring a pump lift which is a difference between the liquid pressure on the discharge side and the liquid pressure on the suction side of the pump main body 3. , A storage unit 7 and a storage unit 7 that store the relationship between the operating frequency, the pump lift, and the flow rate obtained by previously measuring the actual flow rates at the plurality of operating frequencies of the inverter 2 and the plurality of pump lifts. The control unit 6 is provided with a control unit 6 that performs a process of estimating the flow rate at the operation frequency and the pump lift acquired during actual operation based on the relationship between the operation frequency, the pump lift, and the flow rate stored in.

With such a configuration, the liquid pump device 1 can estimate the flow rate in a state where there is little error from the actual flow rate without using a flow meter, and various types similar to the above-mentioned flow rate estimation method. The effect of can be obtained.

Further, the liquid pump device 1 is provided with a suction pressure at a portion where the pressure sensor is connected to the pump main body 3 on the suction side of the pump main body 3 and is supplied as a part of the liquid pump device 1. It is composed of a sensor 4 and a discharge pressure sensor 5 provided at a portion connected to the pump body 3 on the discharge side of the pump body 3 and supplied as a part of the liquid pump device 1. ..

With such a configuration, the liquid pump device 1 can acquire the pump head in the same mode at the time of data acquisition and at the time of actual operation, and can estimate the flow rate more accurately.

By the way, in the above-described embodiment, the relationship between the operating frequency, the pump head, and the flow rate is stored as a data table, but these relationships can also be stored as a function. That is, the actual operating frequency and the flow rate at the pump head can be estimated by calculating using a function.

Specifically, as shown in FIG. 5, the operating frequency, pump head, and flow rate acquired at the time of data acquisition are plotted with the vertical axis as the pump head (P) and the horizontal axis as the flow rate (Q), and pass through each point. By obtaining the optimum curve, a function indicating the so-called PQ characteristics of the liquid pump device 1 can be obtained, and the actual operating frequency and the flow rate at the pump head can be estimated using the function.

At this time, as the function showing the optimum curve, the following equation (1) known as a general equation of PQ characteristics can be used.
P = A ・ Q ^ 2 + B ・ Q ・ (f / F) + C ・ (f ・ F) ^ 2 ・ ・ ・ (1)
However, P is the pump head, Q is the flow rate, f is the actual operating frequency, F is the rated operating frequency, A, B and C are coefficients, "・" indicates multiplication, and "^" indicates power. ing.

In the case of FIG. 5, the graph (G1) shows the PQ characteristics of the liquid pump device 1 at a rated operating frequency, for example 60 Hz. Further, the graph (G2) shows the PQ characteristics of the liquid pump device 1 at an operating frequency of, for example, 40 Hz. Although two graphs are shown in FIG. 3, the same PQ characteristics are obtained for each of the plurality of operating frequencies acquired at the time of data acquisition.

In this way, the configuration that obtains the PQ characteristics by a function, in other words, the configuration that stores the relationship between the operating frequency, the pump head, and the flow rate as a function, and estimates the actual operating frequency and the flow rate at the pump head by calculation using the function. It can also be. Even with such a configuration, various effects similar to those in the above-described embodiment can be obtained, such as being able to estimate the flow rate in a state where there is little error from the actual flow rate without using a flow meter.

By the way, as can be seen from the above equation (1) and as shown in FIG. 5, even if the actual operating frequency (f) is constant, the flow rate with respect to the amount of change in the pump head (P). The amount of change in (Q) is not constant. The amount of change in the flow rate (Q) changes depending on the height of the pump head.

Therefore, the relationship between the operating frequency, the pump head, and the flow rate is divided into a plurality of regions based on the height of the pump head, and the relationship between the operating frequency, the pump head, and the flow rate in each region is stored as a function. You can also do it. Specifically, the pump head is divided into a relatively high high head region and a relatively low low head region, and the relationship between the operating frequency, the pump head, and the flow rate in the high head region and the low head region is used as a function. You can ask. The area to be divided may be three or more.

Specifically, the point P10 shown in FIG. 5 is the graph (G1), that is, the pump head when the valve on the discharge side is fully closed at the rated operating frequency. Note that the intersection of the graph of PQ characteristics and the vertical axis, such as this point P10 and the point P20 described later, indicates the so-called total head of the deadline at the operating frequency.

In the case of FIG. 5, 80% of the total head of the deadline is set as a threshold value, a region above the threshold value is set as a high head region, and a region below the threshold value is set as a low head region. The number of regions to be divided and the threshold value can be appropriately selected. Specifically, in the case of the graph (G1), the left side including the intersection P30 between the graph (G1) and the virtual line horizontal to the horizontal axis passing through the point P11, which is 80% of the point P10, is the high head region. The low head region is on the right side of the intersection P30. Similarly, in the case of the graph (G2), the left side including the intersection P31 between the graph (G2) and the virtual line horizontal to the horizontal axis passing through the point P21 which is 80% of the point P20 is the high head region, and the intersection. The lower lift region is on the right side of P30.

Then, when the high head region and the low head region are set for the PQ characteristics at each operating frequency, as shown by the broken line graph (G3) in FIG. 5, the boundary line that separates the high head region and the low head region becomes. Set. By dividing into a high head region and a low head region in this way and finding a function in each region as in Eq. (1), an appropriate function is selected according to the height of the pump head, and there is less error. The flow rate can be estimated.

Further, in the embodiment, the configuration in which the suction pressure sensor 4 is provided in the suction pipe 8 is illustrated, but the suction pressure sensor 4 is provided in the pump main body 3, more strictly speaking, a part of the structure on the suction side of the pump main body 3. It can be configured. That is, the suction pressure sensor 4 is provided on the suction side of the pump main body 3 at a portion connected to the pump main body 3 or the pump main body 3 and supplied as a part of the liquid pump device 1. Can be done.

Similarly, the discharge pressure sensor 5 can be provided in a part of the structure on the discharge side of the pump main body 3, or more strictly speaking, the pump main body 3. That is, the discharge pressure sensor 5 is provided on the discharge side of the pump main body 3 at a portion connected to the pump main body 3 or the pump main body 3 and supplied as a part of the liquid pump device 1. Can be done.

Even with such a configuration, as described in the embodiment, the suction pressure sensor 4 and the discharge pressure sensor 5 can acquire the pump head in the same state as at the time of data acquisition, so that the possibility of error is reduced. can do. Further, one of the suction pressure sensor 4 and the discharge pressure sensor 5 may be provided on the pump body 3.

Further, in the embodiment, the liquid pump device 1 and the heat source machine 14 are provided separately, but the liquid pump device 1 may be incorporated in the housing of the heat source machine 14. Further, one of the plurality of heat source machines 14 may be used as the master, and the control unit of the master heat source machine 14 may be used as the control device 16.

Further, in the embodiment, the configuration in which two sensors, the suction pressure sensor 4 and the discharge pressure sensor 5, are provided as the pressure sensor is illustrated, but one difference sensor is provided as the pressure sensor, and the pump lift is directly detected. You can also do it.
Further, in the embodiment, an example of linearly interpolating the data table is shown, but a non-linear interpolation configuration can also be used.

Further, similarly to the embodiment, the flow rate can be realized by realizing the flow rate estimation method by using a computer program for causing the control unit 6 to execute the flow rate estimation method shown in the embodiment or a storage medium in which the computer program is stored. It is possible to obtain an effect such as being able to estimate the flow rate of the liquid discharged from the liquid pump device 1 with little error without using a meter.

Although some embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

In the drawing, 1 is a liquid pump device, 2 is an inverter, 3 is a pump body, 4 is a suction pressure sensor (pressure sensor), 5 is a discharge pressure sensor (pressure sensor), 6 is a control unit, 7 is a storage unit, and 8 is a storage unit. Suction pipe (part provided as part of the liquid pump device), 10 is the inlet pipe (external pipe), 11 is the discharge pipe (part provided as part of the liquid pump device), and 13 is the outlet pipe (external). (Piping) is shown.

Claims (7)

A flow rate estimation method that estimates the flow rate of liquid discharged from a liquid pump device.
The liquid pump device includes a pump body driven by an inverter.
The relationship between the pump head, which is the difference between the operating frequency of the inverter, the pressure on the discharge side and the pressure on the suction side of the pump body, and the flow rate of the liquid discharged from the pump body, is set to a plurality of operating frequencies and a plurality. By actually measuring the flow rate, remember in advance about the pump head of
A method for estimating the flow rate of a liquid pump device, which estimates the flow rate at the operating frequency and the pump head acquired during actual operation based on the relationship between the stored operating frequency, the pump head, and the flow rate. As the pump lift, the pressure of the liquid at the portion provided as a part of the liquid pump device on the discharge side of the pump body and the pressure of the liquid at the portion provided as a part of the liquid pump device on the suction side of the pump body. The method for estimating the flow rate of the liquid pump device according to claim 1, wherein the difference between the two and the liquid pump device is used. The first or second aspect of claim 1 or 2, wherein the relationship between the operating frequency, the pump head and the flow rate is stored as a data table, and the actual operating frequency and the flow rate at the pump head are estimated by interpolating the data table. A method for estimating the flow rate of a liquid pump device. Any one of claims 1 to 3, wherein the relationship between the operating frequency, the pump head, and the flow rate is stored as a function, and the actual operating frequency and the flow rate at the pump head are estimated by calculation using the function. The method for estimating the flow rate of the liquid pump device described. The feature is that the relationship between the operating frequency, the pump lift and the flow rate is divided into multiple regions based on the height of the pump lift, and the relationship between the operating frequency, the pump lift and the flow rate in each region is stored as a function. The method for estimating the flow rate of the liquid pump device according to claim 4. The pump body driven by the inverter and
A pressure sensor capable of acquiring the pump head, which is the difference between the pressure of the liquid on the discharge side and the pressure of the liquid on the suction side of the pump body,
A storage unit that stores the relationship between the operating frequency, the pump head, and the flow rate obtained by previously measuring the actual flow rates at the plurality of operating frequencies and the plurality of pump heads of the inverter.
A control unit that performs processing for estimating the flow rate at the operating frequency and the pump head acquired during actual operation based on the relationship between the operating frequency, the pump head, and the flow rate stored in the storage unit.
A liquid pump device characterized by comprising. The pressure sensor
On the suction side of the pump body, a suction pressure sensor provided at a portion supplied as a part of the liquid pump device and
The liquid pump device according to claim 6, wherein the discharge side of the pump body is composed of a discharge pressure sensor provided at a portion supplied as a part of the liquid pump device.

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