JP7217015B2 - pump system - Google Patents

Description

The present invention relates to pump systems.

In sewage treatment, sewage sludge precipitated from sewage is dehydrated by a dehydrator to obtain dehydrated sludge (dehydrated cake). The obtained dehydrated cake is made to flow in the pipe by driving the pump, and is transferred to an incinerator or the like. The dehydrated cake is clay-like and has a large pressure loss during transfer. Therefore, when transferring the dehydrated cake to a distant incinerator or the like, it is necessary to raise the pressure by a pump.

When using a uniaxial eccentric screw pump, it is necessary to increase the number of rotor and stator stages in order to apply high pressure to the dewatered cake. In this case, the rotational torque of the rotor must be increased, and the drive mechanism becomes large and expensive.

Conventionally, by connecting two pumps in series, the load on each pump is reduced, and a compact and inexpensive configuration is achieved. For example, in the pump device disclosed in Patent Document 1, two single-axis eccentric screw pumps are connected in series via an intermediate pipe, and the downstream single-axis eccentric screw pump is driven and controlled based on the pressure in the intermediate pipe. I'm trying Specifically, the control unit of the pump sets an upper limit value and a lower limit value for the pressure measurement value in the intermediate pipe, and performs feedback control on the transfer amounts of the two pumps. If the measured pressure in the intermediate pipe exceeds the upper limit, it is determined that the transfer capacity of the downstream pump has decreased due to wear or deterioration of the stator, and the discharge of the dehydrated cake in the intermediate pipe is delayed. can. Therefore, an instruction to increase the transfer amount by increasing the rotational speed of the downstream pump is output. On the other hand, when the pressure in the intermediate pipe falls below the lower limit, it can be determined that the transfer capability of the downstream pump exceeds the transfer capability of the upstream pump. Therefore, in order to prevent idle operation of the downstream pump, an instruction is output to decrease the rotation speed of the downstream pump and decrease the transfer amount. Such rotation speed correction is sometimes performed for temporary fluctuations in flow rate and pressure, but is also performed to compensate for a decrease in transfer rate due to deterioration of the stator of the pump.

In the above-described pump device, the degree of deterioration of the transfer capability (the degree of wear of the stator) due to use differs between the upstream pump and the downstream pump. For example, if the discharge pressure of the downstream pump is higher than that of the upstream pump, in the initial stage when the stators of both pumps are not worn much, the pressure acting on the downstream pump is higher than that of the upstream (low pressure) pump. The stator on the (high pressure) side pump is prone to wear and the degree of deterioration is large. If the degree of deterioration of the downstream (high-pressure) side pump becomes severe, the pump system as a whole cannot exhibit the desired transfer performance even if the upstream (low-pressure) side pump is not so deteriorated.

However, in the pump device, it is not possible to determine which pump is deteriorated to what degree. For this reason, once a certain period of time has passed since the start of use, the expendable parts, ie, the stators, of both pumps have to be replaced preventively regardless of the state of deterioration of each pump, resulting in a heavy maintenance burden.

Japanese Patent No. 3583809

SUMMARY OF THE INVENTION An object of the present invention is to provide a pump system capable of determining when to perform maintenance on pumps connected in series.

As a means for solving the above-mentioned problems, the present invention provides a positive displacement pump group including a first pump, a second pump connected in series to the downstream side of the first pump, and at least the second pump. and a control means for correcting a decrease in the amount transferred due to deterioration of the pump by driving and controlling at least one of the first pump and the second pump, wherein the control means drives the first pump. The ratio S2/S1 of the first signal S1 indicating the state and the second signal S2 indicating the driving state of the second pump satisfies S2/S1≧CV1, which is equal to or greater than the first threshold value CV1. To provide a pump system that determines that it is time for maintenance of two pumps.

With this configuration, when the deterioration of the second pump is more advanced than that of the first pump, the transfer amount of the second pump becomes insufficient compared to that of the first pump, so the driving state of the second pump is changed. Control is exercised to increase the transfer capacity of the second pump. After that, if the deterioration of the second pump progresses compared to the first pump, the same control is repeated such that the transfer capability of the second pump is increased each time. As a result, the ratio S2/S1 between the first signal S1 indicating the driving state of the first pump and the second signal S2 indicating the driving state of the second pump is increased. In other words, if the ratio S2/S1 increases, it can be determined that the deterioration of the second pump is more advanced than that of the first pump. Therefore, if the ratio S2/S1 satisfies S2/S1≧CV1, which is equal to or greater than the first threshold value CV1, it is determined that it is time for maintenance of the second pump. This can encourage maintenance of the second pump.

As a means for solving the above problems, the present invention provides a positive displacement pump group including a first pump and a second pump connected in series to the downstream side of the first pump, and at least the first pump. and a control means for correcting a decrease in the amount transferred due to deterioration of the pump by driving and controlling at least one of the first pump and the second pump, wherein the control means drives the first pump. The ratio S2/S1 of the first signal S1 indicating the state and the second signal S2 indicating the driving state of the second pump satisfies S2/S1≦CV2, that is, the second threshold value CV2 or less. To provide a pump system that determines that it is time for maintenance of one pump.

With this configuration, when the deterioration of the first pump is more advanced than that of the second pump, the transfer amount of the first pump becomes insufficient compared to that of the second pump, so the driving state of the first pump is changed. Control is exercised to increase the transfer capacity of the first pump. After that, if the deterioration of the first pump progresses compared to the second pump, the same control is repeated such that the transfer capability of the first pump is increased each time. As a result, the ratio S2/S1 between the first signal SV1 indicating the driving state of the first pump and the second signal S2 indicating the driving state of the second pump becomes smaller. In other words, if the ratio S2/S1 becomes smaller, it can be determined that the deterioration of the first pump is more advanced than that of the second pump. Therefore, when the ratio S2/S1 satisfies S2/S1≦CV2, which is the second threshold value CV2 or less, it is determined that it is time for maintenance of the first pump. This can encourage maintenance of the first pump.

As a means for solving the above problems, the present invention provides a positive displacement pump group including a first pump and a second pump connected in series to the downstream side of the first pump, the first pump or control means for correcting a decrease in transfer amount due to deterioration of at least one of the second pumps by driving and controlling at least one of the first pump and the second pump; a variation range of the ratio S2/S1 of the first signal S1 indicating the driving state and the second signal S2 indicating the driving state of the second pump when the first pump and the second pump are operating normally; and storage means for storing the change tendency until the first pump or the second pump fails, and the control means stores, when the ratio S2/S1 changes beyond the fluctuation range, A pump system is provided that predicts the maintenance timing of the first pump or the second pump based on the change tendency of the ratio S2/S1.

With this configuration, from the normal operation to the failure, the change in the ratio S2/S1 between the first signal S1 indicating the driving state of the first pump and the second signal S2 indicating the driving state of the second pump is measured. Based on the data, the timing for maintenance of the first pump or the second pump can be predicted. Therefore, it is possible to improve the prediction accuracy of the maintenance timing and perform the maintenance work in a planned manner.

As a means for solving the above problems, the present invention provides a positive displacement pump group including a first pump and a second pump connected in series to the downstream side of the first pump, the first pump or a control means for correcting a decrease in transfer amount due to deterioration of at least one of the second pumps by driving and controlling at least one of the first pump or the second pump, wherein the control The means stores a ratio S2/S1 of a first signal S1 indicating the driving state of the first pump and a second signal S2 indicating the driving state of the second pump a plurality of times at predetermined time intervals. and a pump system having a time-series analysis function of predicting the maintenance timing of the first pump or the second pump by predicting the change tendency of the ratio S2/S1.

With this configuration, in pump systems with various specifications, based on the changing tendency of the ratio S2/S1 between the first signal S1 indicating the driving state of the first pump and the second signal S2 indicating the driving state of the second pump, It is possible to predict the maintenance timing of the first pump or the second pump without past data reflecting operating conditions and installation environment.

As a means for solving the above problems, the present invention provides a positive displacement pump group including a first pump and a second pump connected in series to the downstream side of the first pump, the first pump or a control means for correcting a decrease in transfer amount due to deterioration of at least one of the second pumps by driving and controlling at least one of the first pump or the second pump, wherein the control The means stores the ratio S2/S1 of the first signal S1 indicating the driving state of the first pump and the second signal S2 indicating the driving state of the second pump, based on the result of storing the ratio S2/S1. Provided is a pump system having an artificial intelligence function that predicts the maintenance timing of the first pump or the second pump by deep learning of change trends.

With this configuration, the more past data is accumulated, the more the actual data of the ratio S2 / S1 and other data, such as weather and temperature changes, can be used to predict maintenance of the pump by deep learning by artificial intelligence. A variety of related data can also be used to find the trend of change in the ratio S2/S1 and improve the prediction accuracy.

As a means for solving the above problems, the present invention provides a positive displacement pump group including a first pump and a second pump connected in series to the downstream side of the first pump, and at least the first pump. and a first upper limit value UL1 indicating the maintenance timing of the first pump by controlling the driving of at least one of the first pump and the second pump. wherein the first signal S1 indicating the driving state of the first pump satisfies S1>UL1, which is greater than the first upper limit value UL1, so that the first To provide a pump system that determines that one pump is due for maintenance.

With this configuration, both the first pump and the second pump deteriorate, and the ratio S2/S1 of the first signal S1 indicating the driving state of the first pump and the second signal S2 indicating the driving state of the second pump changes. Even if it is difficult to judge the maintenance timing of the first pump only from the above, it is possible to cope with the situation. That is, when the first pump and the second pump are similarly deteriorated, the ratio S2/S1 changes at a numerical value indicating that the driving conditions of both pumps are within the normal range, but the transfer capacity of the entire pump system decreases. do. In this case, even if the drive state is manually or automatically changed to increase the transfer capacity of the first pump, the transfer efficiency of the entire pump system will not be recovered and will eventually reach its limit. Therefore, if the first signal value S1 exceeds the first upper limit value UL1 and satisfies S1>UL1, it can be determined that the first pump has deteriorated, and the need for maintenance can be notified.

As a means for solving the above-mentioned problems, the present invention provides a positive displacement pump group including a first pump, a second pump connected in series to the downstream side of the first pump, and at least the second pump. a second upper limit value UL2 indicating the timing of maintenance of the second pump; wherein the second signal S2 indicating the driving state of the second pump satisfies S2>UL2, which is greater than the second upper limit value UL2, so that the second To provide a pump system that determines that two pumps are due for maintenance.

With this configuration, both the first pump and the second pump deteriorate, and the ratio S2/S1 of the first signal S1 indicating the driving state of the first pump and the second signal S2 indicating the driving state of the second pump changes. Even if it is difficult to detect the maintenance timing of the second pump only from the above, it is possible to cope with the situation. That is, when the first pump and the second pump are similarly deteriorated, the ratio S2/S1 changes at a numerical value indicating that the driving conditions of both pumps are within the normal range, but the transfer capacity of the entire pump system decreases. do. In this case, even if the driving state of the second pump is changed manually or automatically in order to increase the transfer capacity, the transfer efficiency of the entire pump system will not be recovered and will eventually reach its limit. Therefore, if the second signal S2 exceeds the second upper limit value UL2 and satisfies S2>UL2, it can be determined that the second pump has deteriorated, and the need for maintenance can be notified.

Preferably, the control means drives and controls the second pump based on an intermediate pressure between the first pump and the second pump and a discharge side pressure of the second pump.

As a means for solving the above-mentioned problems, the present invention provides a positive displacement pump group consisting of a plurality of pumps connected in series, and a decrease in transfer amount due to deterioration of the (i) pump among the pumps, control means for correcting by driving and controlling the (i+1)th pump; (i)th signal S _i indicating the driving state of the (i)th pump; storage means for storing a (j)th signal S _j indicating a driving state, a ratio S _i /S _j of both signals, and a threshold value CV _k for the ratio S _i /S _j ; Based on the information stored in the storage means, the ratio S of the ( _i )th signal Si indicating the driving state of the (i)th pump and the ( _j )th signal Sj indicating the driving state of the (j)th pump Provided is a pump system that determines that it is time for maintenance of the (i)th pump by satisfying S _i /S _j ≧CV _k where _i /S _j is equal to or greater than a threshold value CV _k .

With this configuration, even when a plurality of pumps are connected in series, it is possible to determine which pump is due for maintenance.

Preferably, the control means determines maintenance timing for all combinations of the two pumps.

It is preferable that the control means sets the maintenance timing of each pump to the period judged to be the shortest.

The storage means further includes (i) a signal Si indicating the drive state of the ( _i ) pump and (j) signal Si indicating the drive state of the (j) pump when the pump is in normal operation. ) the fluctuation range of the ratio S _i /S _j of the signal S _j and the tendency of change until the (i)th pump reaches the maintenance timing, and the control means controls the ratio S _i /S _j to change according to the fluctuation It is preferable to predict the maintenance timing of the (i)th pump based on the changing tendency of the ratio S _i /S _j when it changes beyond the range.

With this configuration, even when a plurality of pumps are connected in series, the maintenance timing of each pump can be predicted.

The control means determines whether or not the (i)th signal Si indicating the driving state of the ( _i )th pump satisfies _Si≤SR , which is within a set range. (i) It is preferable to determine that it is time for pump maintenance.

With this configuration, even when a plurality of pumps are connected in series and when all the pumps are similarly deteriorated, it is possible to determine that it is time for maintenance.

The control means controls the ratio S ₁ /S _j of the (i)th signal Si indicating the driving state of the ( _i )th pump and the (j)th signal Sj indicating the driving state of the ( _j )pump. is stored a plurality of times at predetermined time intervals to predict the change tendency of the ratio S _i /S _j , thereby predicting the maintenance timing of the (i)th pump. is preferred.

With this configuration, when a plurality of pumps are connected in series, the maintenance timing of each pump can be predicted without past data reflecting operating conditions and installation environment.

The control means controls the ratio S _i /S _j of the (i)th signal Si indicating the driving state of the (i)th pump and the (j) _th signal Sj indicating the driving state of the ( _j )th pump. It is preferable to have an artificial intelligence function that predicts the maintenance timing of the (i)th pump by performing deep learning on the change tendency of the ratio S _i /S _j based on the stored results.

With this configuration, the more past data is accumulated, the more the prediction accuracy can be improved by deep learning using artificial intelligence.

Preferably, the first pump and the second pump are single eccentric screw pumps.

In the present invention, the signal value indicating the driving state of the pump may be a driving command value output from the control device to each pump, or a measured value of the driving state of each pump by sensors. good too.

According to the present invention, it is possible to determine when to replace pumps connected in series.

1 is a schematic diagram of a pump system according to a first embodiment; FIG. 2 is a flowchart showing drive control in the pump system shown in FIG. 1; FIG. 3 is a flow chart showing maintenance diagnosis processing in FIG. 2 ; FIG. FIG. 3 is a flow chart showing maintenance prediction processing of FIG. 2 ; FIG. FIG. 2 is a graph showing changes in the actual data of the command value ratio in the pump system shown in FIG. 1 and the approximate expression based on the stored data; FIG. It is a graph which shows the relationship between progress of the operating time of the pump system which concerns on 1st Embodiment, and the rotational speed ratio of a motor. It is a schematic diagram of a pump system according to a second embodiment. 8 is a flowchart showing drive control in the pump system shown in FIG. 7; FIG. 9 is a flow chart showing operation start processing of FIG. 8 ; FIG. FIG. 9 is a flowchart showing a partial voltage control process of FIG. 8; FIG. FIG. 9 is a flow chart showing maintenance diagnosis processing of FIG. 8 ; FIG. FIG. 9 is a flow chart showing maintenance prediction processing of FIG. 8 ; FIG.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the following description is essentially merely an example, and is not intended to limit the present invention, its applications, or its uses. Moreover, the drawings are schematic, and the ratio of each dimension is different from the actual one.

(First embodiment)
FIG. 1 shows a pump system according to a first embodiment. In this pump system, a first pump 1 and a second pump 2 are connected in series by a U-shaped intermediate pipe 3 . Here, both the first pump 1 and the second pump 2 are single eccentric screw pumps. The first pump 1 and the second pump 2 constitute a positive displacement pump group. After the first pump 1 applies pressure to the material to be conveyed, the second pump 2 can apply further pressure to increase the pressure. That is, the first pump 1 functions as a low-pressure side pump, and the second pump functions as a high-pressure side pump.

In the first pump 1 , a first stator 5 , a first rotor 6 , and a screw rod 7 are accommodated within a first casing 4 .

The first casing 4 is composed of a first conveying portion 8 in which the first stator 5 and the first rotor 6 are housed, and a first container portion 9 in which the screw rod 7 is housed. The first conveying part 8 has a cylindrical shape, one end of the intermediate pipe 3 is connected to the discharge part on one end side, and the other end is connected to the first container part 9 . The first container portion 9 has a diameter larger than that of the first conveying portion 8, and has a cylindrical suction portion 10 extending upward from the central portion. A material to be conveyed (here, a dehydrated cake) is supplied from a stirrer 11 through a suction part 10 .

The first stator 5 is made of an elastic material such as rubber or resin (for example, silicone rubber or fluororubber) that is selected according to the fluid to be conveyed, and is formed into a cylindrical shape (for example, a circular cross-sectional shape). . The center hole 5a of the first stator 5 has an inner peripheral surface of n-stripes and a single-stage or multi-stage internal thread. The first stator 5 is attached to the first conveying portion 8 in close contact with the inner peripheral surface thereof.

The first rotor 6 has a shaft body made of a metal material such as stainless steel, and has n-1 threads and a single-stage or multi-stage male screw. The first rotor 6 is arranged in the center hole 5a of the first stator 5 and forms a conveying space 5b connected in the longitudinal direction thereof. One end of the first rotor 6 is connected to one end of the screw rod 7 via a first universal joint 12 .

A rotating shaft of a first motor 13 is connected to the other end of the screw rod 7 . The rotation speed of the first motor 13 is changed according to the difference in frequency set by the first inverter 14 . The power supplied from the first inverter 14 is controlled by the control device 15 . That is, a first signal S1 (first drive command value) is output from the control device 15 to the first inverter 14, and the rotation speed of the first pump 1 (voltage and frequency of AC output to the first motor 13) is adjusted. be done. If the pump is a positive displacement pump such as a uniaxial eccentric screw pump, the correlation between the rotation speed drive command value from the control device 15 and the actual rotation speed of the pump does not change significantly. Therefore, it may be determined that the first signal S<b>1 indicates the driving state of the first motor 13 , that is, the first pump 1 . Driving the first motor 13 causes the screw rod 7 and the first rotor 6 to rotate. The first rotor 6 rotates inside the first stator 5 and revolves along the inner peripheral surface of the first stator 5 . That is, the first rotor 6 rotates eccentrically within the center hole of the first stator 5 to convey the dehydrated cake in the conveying space toward the intermediate pipe 3 .

In the second pump 2 , a second stator 17 and a second rotor 18 are housed inside the second casing 16 .

The second casing 16 is composed of a second transport section 19 in which the second stator 17 and the second rotor 18 are accommodated, and a second container section 20 . The second conveying portion 19 has a cylindrical shape, and the other end of the intermediate pipe 3 is connected to the suction portion 10 on the one end side, and the second container portion 20 is connected to the other end. The second container part 20 has a larger diameter than the second transport part 19 and a tubular discharge part 21 extends therefrom. The dehydrated cake discharged from the discharge unit 21 is supplied to a distant incinerator or the like.

The second stator 17 and the second rotor 18 have the same configurations as the first stator 5 and the first rotor 6, respectively. The second rotor 18 is arranged in the center hole of the second stator 17 and forms a conveying space 16b connected in the longitudinal direction thereof. One end of the second rotor 18 is connected to the rotating shaft of a second motor 23 via a second universal joint 22 . The rotation speed of the second motor 23 is changed according to the difference in frequency set by the second inverter 24 . The power supplied from the second inverter 24 is controlled by the control device 15 . That is, a second signal S2 (second drive command value) is output from the control device 15 to the second inverter 24, and the rotation speed of the second pump 2 (voltage and frequency of the AC output to the second motor 23) is adjusted. be done. Therefore, as with the first pump 1, the second signal S2 indicates the driving state of the second motor 23, that is, the second pump 2. FIG. The drive of the second motor 23 causes the second rotor 18 to rotate. The rotation of the second rotor 18 is the same as that of the first rotor 6 , rotates inside the second stator 17 and revolves along the inner peripheral surface of the second stator 17 . That is, the second rotor 18 is eccentrically rotated within the center hole of the second stator 17 to convey the dehydrated cake in the conveying space to the second container portion 20 .

A first pressure sensor 25 is provided in the middle of the intermediate pipe 3 connecting the first pump 1 and the second pump 2 . The pressure in the intermediate pipe 3 detected by the first pressure sensor 25 is input to the control device 15 . A second pressure sensor 26 is provided at the discharge portion 21 of the second pump 2 . The pressure of the dehydrated cake discharged from the second pump 2 detected by the second pressure sensor 26 is input to the control device 15 . The control device 15 outputs control signals to the first inverter 14 and the second inverter 24 based on input signals from the first pressure sensor 25 and the second pressure sensor 26 . Further, the control device 15 determines the maintenance timing of the first pump 1 or the second pump 2 based on control signals (first drive command value and second drive command value) output to the inverters 14 and 24 .

Next, the operation of the pump system configured as described above will be described.

As shown in the flowchart of FIG. 2, first, the stirrer 11 is driven to stir the supplied dehydrated cake (step S1). The stirred dehydrated cake is sent to the first container portion 9 of the first pump 1 . When a predetermined time T (for example, 5 to 10 seconds) has passed since the start of stirring by the stirrer 11 (step S2), the first motor 13 is started to rotate, and the screw rod 7 and the first rotor 6 are rotated (step S3). The rotation speed of the first motor 13 is a value corresponding to the weight of the dehydrated cake supplied from the stirrer 11 per unit time.

Driving the first motor 13 increases the pressure in the intermediate pipe 3 . When the pressure detected by the first pressure sensor 25 reaches a preset value (set value), the driving of the second pump 2 is started (step S4). As a result, the dehydrated cake is discharged from the second pump 2 .

A first pressure P1 in the intermediate pipe 3 detected by the first pressure sensor 25 and a second pressure P2 at the discharge portion 21 of the second pump 2 detected by the second pressure sensor 26 are read (step S5). . Then, it is determined whether or not the ratio P1/P2 between the first pressure P1 and the second pressure P2 is within the set range (step S6). The setting range can be, for example, 1/2-c≤P1/P2≤1/2+c (c is a constant).

If the ratio P1/P2 is within the set range, it is determined that the driving rotation speeds of the first motor 13 and the second motor 23 are appropriate, and the process proceeds to step S9. If the ratio P1/P2 is not within the set range, PID (Proportional-Integral-Differential) control is executed to adjust the driving states of the motors 13 and 23 .

In PID control, when the ratio P1/P2 exceeds the upper limit of the set range, a second signal S2 (second drive command value) is output to the second inverter 24 in order to increase the rotation speed of the second pump 2. increase the As a result, the transfer amount of the dehydrated cake by the second pump 2 increases.

On the other hand, when the ratio P1/P2 falls below the lower limit of the set range, the value of the second signal S2 output to the second inverter 24 is decreased in order to decrease the rotational speed of the second motor 23 . As a result, the transfer amount of the dehydrated cake by the second pump 2 is reduced. Note that the first signal S1 (first drive command value: here, the number of revolutions of the first pump 1), which is a control signal to the first inverter 14 that controls the amount of transfer of the first pump 1, is controlled by the entire pump system. It is set manually or automatically based on the desired flow rate and the operation status of the entire sewage treatment facility, and is input from the outside.

When transferring the dewatered cake, if the first stator 5 of the first pump 1 wears and deteriorates and the transfer capacity is reduced, the first signal S1 (rotational speed of the first pump 1) is increased to compensate for the transferred amount. Let On the other hand, if the second stator 17 of the second pump 2 is worn and deteriorated and the transfer capability is reduced, the pressure values detected by the first pressure sensor 25 and the second pressure sensor 26 are detected by feedback control. 2 signal S2 (here, the number of revolutions of the second pump 2) is increased. In general, the degree of wear and deterioration of the first stator 5 and the second stator 17 are different. Therefore, the correction of the first signal S1 and the second signal S2 is performed for the pump whose degree of wear and deterioration progresses rapidly. As a result, as long as the pump system continues to operate without replacing the stator, S2/S1, which is the ratio of the first signal S1 and the second signal S2 (motor rotation speed ratio), tends to increase. The change in the ratio S2/S1 between the first signal S1 and the second signal S2 further accelerates as one of the stators approaches the time when it has deteriorated enough to require replacement. Using this phenomenon, the control device 15 judges or predicts the maintenance timing of the first pump 1 or the second pump 2 .

When the driving of the second motor 23 is started, a maintenance diagnosis process for the pump is executed (step S9).

In the pump maintenance diagnosis process, as shown in the flowchart of FIG. 3, first, the first signal S1 and the second signal S2 are stored at predetermined time intervals (step S9-1). Then, the ratio S2/S1 (here, the frequency ratio) between the first signal S1 and the second signal S2 is obtained (step S9-2). Subsequently, it is determined whether or not the ratio S2/S1 is equal to or greater than a preset first threshold value CV1 (SV2/SV1≧CV1) (step S9-3). If S2/S1≥CV1, it means that the driving rotation speed of the second pump 2 has increased more than necessary. In other words, it is determined that the second pump 2 needs maintenance (maintenance time) because the discharge amount per rotation of the second rotor 18 is insufficient and the second stator 17 wears out. and notify it (step S9-7).

It is determined whether or not the ratio S2/S1 is equal to or less than a preset second threshold value CV2 (S2/S1≤CV2) (step S9-4). If S2/S1≤CV2, it means that the driving rotation speed of the first pump 1 has increased more than necessary. In other words, it is determined that it is time for maintenance of the first pump 1 due to insufficient discharge amount per rotation of the first rotor 6 and wear of the first stator 5 (step S9-7).

Even if CV1<S2/S1<CV2 is satisfied and it is determined that there is no problem, both the first pump 1 and the second pump 2 may deteriorate. Therefore, it is determined whether or not the first signal S1 exceeds the first upper limit value UL1 (S1>UL1) (step S9-5). Also, it is determined whether or not the second signal S2 exceeds the second upper limit value UL2 (S2>UL2) (step S9-6). If S1>UL1, it is determined that the first pump 1 is due for maintenance, and if S2>UL2, it is determined that the second pump 2 is due for maintenance.

When the use of the first pump 1 and the second pump 2 is newly started, the stator of the second pump 2 to which a higher pressure is applied tends to deteriorate due to wear and the like. Therefore, it is predicted that the ratio S2/S1 will first exceed the first upper limit value UL1. Then, if the deteriorated stator of the second pump 2 is replaced, the deterioration of the stator of the first pump 1 will have an effect. In this case, it is predicted that the ratio S2/S1 will be less than the second upper limit value UL2.

After the pump maintenance diagnosis process is completed, the pump maintenance prediction process is executed (step S10).

In the pump maintenance prediction process, as shown in the flowchart of FIG. 4, the ratio S2/S1 is stored at predetermined intervals (step S10-1). Then, it is determined whether or not the ratio S2/S1 is within a previously stored variation range CR (LCR≤S2/S1≤UCR) (step S10-2). For the fluctuation range, if there is a pump whose maintenance period has been previously determined and the stator has been replaced, that data is used. In this case, it is preferable to set a threshold with a margin above and below the stored upper and lower limit values of the amplitude of the ratio S2/S1.

FIG. 5 is a graph showing temporal changes in the ratio S2/S1. In FIG. 5, the solid line indicates the performance data, that is, the change in the ratio S2/S1 between the first signal S1 and the second signal S2 stored at predetermined time intervals. A dotted line indicates a change in the approximation formula calculated from the past stored data. As can be seen from this graph, the actual data change almost according to the approximation formula. Therefore, the maintenance timing can be predicted as follows.

If LCR≤S2/S1≤UCR, it is determined that each pump is operating properly, and maintenance prediction is not performed. If S2/S1>LCR or UCR<S2/S1, the ratio S2/S1 reaches the first upper limit value CV1 or the second upper limit value CV2 based on a pre-stored approximation formula showing the change tendency of S2/S1. more precisely, the operation time until each pump is fully deteriorated is predicted (step S10-3). The obtained data can be displayed on a monitor (not shown) to notify the operator of the timing of replacement, or can be communicated to a maintenance company via the Internet so that maintenance work can be performed before the pump maintenance time comes. You may It should be noted that the use of past stored data may be a statistical method or the like instead of the approximation formula.

As described above, the dehydrated cake transfer process from step S1 to step S8, the pump maintenance diagnosis process of step S9, and the pump maintenance prediction process of step S10 are repeated until the transfer work of the dehydrated cake is completed. .

FIG. 6 is a graph showing the relationship between the elapsed operating time of the pump system and the ratio of the first signal S1 to the second signal S2 (motor rotation speed ratio) S2/S1. The speed ratio S2/S1 has remained below 1 since the start of use of the pump, but after a certain period of time has passed, it exceeds 1 and increases rapidly. In this example, the stator is replaced when the elapsed time from the start of use becomes the set time. Therefore, if the timing of maintenance is predicted according to the degree of change in the speed ratio S2/S1 and the replacement work is executed before the operation is stopped, the work can be carried out in a planned manner.

In addition, the stator is replaced again after a set time has elapsed since the stator was replaced. However, in the second stator replacement, although the speed ratio S2/S1 exceeds the value 1, it does not increase rapidly, and it is presumed that the deterioration of the stator has not progressed that much. Therefore, if the method according to the first embodiment is adopted, the maintenance period can be postponed, and it can be expected that unnecessary replacement work will be unnecessary.

As described above, the pump system according to the first embodiment has the following advantages.
(1) It is possible to determine when to perform maintenance on the pump, which was not possible in the past. In particular, it can be determined which of the two-stage pumps is due for maintenance. Therefore, only one of the pumps needs to be maintained, and the maintenance work can be performed efficiently. It is also economical because it eliminates the need to replace unnecessary parts in maintenance-free pumps.
(2) It is possible to predict the maintenance timing of the pump, which has not been considered conventionally. That is, it is possible to predict the timing of maintenance before parts replacement or the like becomes necessary, and to prepare for maintenance work in a planned manner. As a result, it is possible to prevent the occurrence of a problem such as a delay in the conveying process of the dehydrated cake due to sudden stoppage of the pump system at an unexpected time.

(Second embodiment)
FIG. 7 shows a pump system according to a second embodiment. In this pump system, a plurality of pumps 31 consisting of a first pump 31a, a second pump 31b, . Each pump 31 is a uniaxial eccentric screw pump similar to that of the first embodiment. Therefore, the description of the configuration is omitted here. A fluid (here, dehydrated cake) is supplied to the first pump 31 a through the hopper 32 . Inside the hopper 32, a stirring blade (not shown) is rotationally driven. The dehydrated cake is stirred by the rotation of the stirring blades and supplied into the first pump 31a.

A pressure gauge 34 detects the pressure in the pipe 33 connecting the pumps 31 . A first pressure gauge 34a is provided in a first pipe 33a connecting the first pump 31a and the second pump 31b, and a first pressure gauge 34a is provided in a second pipe 33b connecting the second pump 31b and the third pump 31c. The pressure gauge 34b is the second pressure gauge 34b, and the (i)th pressure gauge is provided in the (i)th pipe connecting the (i-1)th pump and the (i)th pump. The detected pressure is input to controller 36 . In addition, a flow meter 35 is provided in addition to the pressure gauge 34 in the pipe 33 leading to the transfer destination on the most downstream side. The flow rate detected by the flow meter 35 is also input to the controller 36 . The control device 36 has a storage section 36a that stores input data and a processing section 36b that processes the stored data. The control device 36 controls the rotational speed of each motor (not shown) that is the driving source of each pump 31 based on the input pressure value and flow rate value. A uniaxial eccentric screw pump having the same specification is used for each pump 31 . Therefore, the rotational speed of the rotor in each pump 31 is set to be the same in the initial state, and the boost value is also the same.

The operation of the pump system having the above configuration will be described.

As shown in the flowchart of FIG. 8, first, a process for starting operation of the pump 31 is executed (step S11). After all the pumps 31 are started to be driven, the partial pressure control process of the pumps 31 is executed (step S12), and the transport of the dehydrated cake is started. When the transportation of the dehydrated cake is started, the maintenance diagnosis processing of the pump 31 (step S13) and then the maintenance prediction processing of the pump 31 (step S14) are executed. Then, based on the results of the maintenance diagnosis process and the maintenance prediction process, an operation termination process for stopping the pump system is appropriately executed (step S15).

(Operation start processing)
In the process of starting operation of the pump 31, as shown in the flowchart of FIG. 9, the stirring blade in the hopper 32 is rotationally driven (step S11-1), and the dehydrated cake is stirred and supplied to the first pump 31a. Then, i is set to 1 (i is a natural number) (step S11-2), and the driving of the first pump 31a is started (step S11-3). When a predetermined time has passed since the start of the first pump 31a (step S11-4), i=i+1 is set (step S11-5), and the driving of the second pump 31b is started (step S11-6). Thereafter, until i=n and all the pumps 31 are completely driven (step S11-7), the process returns to step S11-4, and i=i+1 every time a predetermined time elapses from the start of driving of the pump 31 on the upstream side, Start driving the pump 31 on the downstream side. Then, when all the pumps 31 are driven, the process shifts from the operation start process to the partial pressure control process.

(Partial voltage control processing)
In the pump partial pressure control process, as shown in the flowchart of FIG. 10, i is set to 1 (step S12-1), and the first pipe 33a connecting the first pump 31a and the second pump 31b is provided with A first pressure value P1 detected by the _first pressure gauge 34a is read (step S12-2). Then, i=i+1 (step S12-3), and the second pressure value P2 detected by the _second pressure gauge 34b provided in the second pipe 33b connecting the second pump 31b and the third pump 31c is Read (step S12-4). Subsequently, the ratio (pressure ratio) P ₁ /P ₂ between the first pressure value and the second pressure value is calculated (step S12-5), and the calculated pressure ratio P ₁ /P ₂ is within the reference pressure ratio range R. It is determined whether or not there is (step S12-6). Here, the reference pressure ratio range R is LLV≦R≦ULV. In addition, LLV is the lower limit that satisfies LLV = i / (i + 1) - a (a is a fixed value), and ULV is the upper limit that satisfies ULV = i / (i + 1) + b (b is a fixed value) is.

When the calculated pressure ratio P ₁ /P ₂ is equal to or less than the lower limit value of the reference pressure ratio range R (step S12-6: YES), the second pump 31b conveys a larger amount of dehydrated cake than the first pump 31a. You can tell that it has passed. Therefore, the rotational speed of the second pump 31b is reduced (step S12-7) to reduce the amount of dehydrated cake conveyed by the second pump 32b. As a result, the amount of dehydrated cake conveyed by the second pump 31b becomes smaller than that by the first pump 31a, and the pressure in the first pipe 33a rises.

When the calculated pressure ratio P ₁ /P ₂ exceeds the upper limit of the reference pressure ratio range R (step S12-6: NO), the amount of dehydrated cake conveyed by the second pump 31b is smaller than that by the first pump 31a. It can be judged that it has become too much. Therefore, the rotation speed of the second pump 31b is increased (step S12-8) to increase the transport amount of the dehydrated cake by the second pump 31b. As a result, the amount of dehydrated cake conveyed by the second pump 31b becomes greater than that by the first pump 31a, and the pressure in the first pipe 33a drops.

Thereafter, the process returns to step S12-3 to set i=i+1, and in step S12-4, the pressure value P _i+1 detected by the pressure gauge provided in the pipe 33 on the downstream side is sequentially read. Then, in step S12-5, the ratio P _i /P i+1 between the (i)-th pressure value P _i and the (i+1)-th pressure value P _{i +1} is calculated, and in step S12-6, this calculated pressure ratio P _i /P It is determined whether _i+1 is within the reference pressure ratio range R. If the calculated pressure ratio P _i /P _i+1 is equal to or lower than the lower limit of the reference pressure ratio range R, the rotational speed of the (i+1)th pump is reduced in step S12-7. If the calculated pressure ratio P _i /P _i+1 exceeds the upper limit of the reference pressure ratio range R, the rotational speed of the (i+1)th pump is increased in step S12-8.

The degree of increase in the rotation speed of each pump 31 may be increased by a predetermined constant value, or may be PID-controlled so as to become the median value of the reference pressure ratio range R. Further, the driving control of each pump 31 may be performed by the pump 31 on the upstream side instead of the downstream side among the pumps adjacent upstream and downstream. When the drive control of all the pumps 31 is thus completed (step S12-9), the process shifts from the partial pressure control process to the maintenance diagnosis process.

(Maintenance diagnosis processing)
In the maintenance diagnosis process of the pump 31, as shown in the flowchart of FIG. 11, i=1 (step S13-1), the rotation speed of the first pump 31a The first signal S1 indicating the drive state of the first pump 31a, which is a speed instruction value (the same applies to other pumps) is read (step _S13-2 ). Thereafter, as i=i+1 (step S13-3), the rotation speed of the (i+1)th pump located downstream is sequentially increased until i=n (n is the total number of pumps) (step S13-5). Read (step S13-4).

If the rotational speeds of all the pumps 31 are read in this way, the speed ratio S _i /S _j (i: the pump to be judged, j: any pump other than the one to be judged (j is a natural number) for the combination of all the pumps 31 ) is calculated and stored (step S13-6). Then, it is determined whether or not all calculated speed ratios S _i /S _j are normal (step S13-7). That is, it is determined whether or not the calculated speed ratio S _i /S _j satisfies S _i /S _j ≧CV _k , which is equal to or greater than the upper limit value CV _k (k is a natural number) set for each combination of pumps 31. do. If the calculated speed ratio SP _i /SP _j is equal to or greater than the upper limit value (step S13-7: YES), it is determined that the stator (or rotor) of the pump 31 has deteriorated, and the relevant pump 31 is scheduled for maintenance. This is notified (step S13-9).

In this manner, in the maintenance diagnosis process, the calculated speed ratio S _i /S _j is compared with the set upper limit value CV _k for all combinations of pumps 31 to determine whether or not it is time for maintenance in a round-robin manner. I'm trying For example, if a certain pump 31 is matched with all other pumps, it is determined that it is time for maintenance. As a result, even if two or more pumps 31 have the same degree of deterioration for some reason, if there is at least one pump 31 with a different degree of deterioration, the timing of maintenance can be determined individually by comparing the speed ratios. can be done.

On the other hand, if the calculated speed ratio S _i /S _j is less than the upper limit value CV _k (step S13-7: NO), the rotational speeds SP _i of all the pumps 31 are within the set (specification) range SR. It is determined whether or not _i ≤ SR is satisfied (step S13-10). This is because if all the pumps 31 have substantially the same degree of deterioration, it cannot be determined based only on the speed ratio. If there is no problem in any determination, the maintenance diagnosis process is terminated. If S _i ≦SR is not satisfied, similarly to the above, it is notified that the relevant pump 31 is due for maintenance (step S13-9).

In the same way, it is determined whether or not the speed ratio _Si / _{Sk satisfies Si/Sj≧CVk and each rotational speed Si satisfies Si ≦ SR for all combinations} of pumps 31. (Step S13-10). The processing from step S13-7 to step S13-9 is repeated for all combinations of pumps 31, and when all processing is completed, the pump 31 determined to be maintenance time in step S13-9 is notified to the user. is notified (step S13-11). At this time, the maintenance timing is determined for the combination of a plurality of different pumps 31 for the (i)th pump. It is preferable to In this way, when it is determined whether or not it is time for maintenance for all combinations of pumps 31, the process proceeds to maintenance prediction processing.

(Maintenance prediction processing)
In the maintenance prediction process for the pump 31, the progress of deterioration of each pump is predicted based on the speed ratio calculated in the maintenance diagnosis process.

That is, the relationship between the speed ratio of the two pumps 31 and the degree of deterioration is stored in advance. In general, the speed ratio of a pump tends to remain almost unchanged until the elapsed time from the start of use (total pump driving time) reaches a certain value, and then gradually increases. Therefore, the speed ratio at which maintenance of the pump 31 is required due to deterioration is defined as a limit value, and set values SV are provided for warning the user at multiple stages up to this limit value. As the set value SV, depending on the difference in the period until the maintenance timing, for example, 30 days remaining for SV1 and 15 days remaining for SV2 can be determined.

Then, as shown in the flowchart of FIG. 12, the speed ratio S _i /S _j calculated in the maintenance diagnosis process is read for each combination of pumps 31 (step S14-1). Subsequently, it is determined whether or not the read calculated speed ratio S _i /S _j is greater than or equal to the set value SV (step S14-2). If the calculated speed ratio S _i /S _j is less than the set value SV, it is determined that the pump 31 is normal (step _{S14-3 )} . , and the degree of deterioration of the corresponding pump is warned according to the set value SV (step S14-4). Then, these processes are executed for all combinations of pumps 31 (step S14-5). At this time, as a result of judging the degree of deterioration of the (i)-th pump 31 between two or more different pumps 31, the degree of deterioration may differ, and the period until the maintenance time may differ. . In this case, it is preferable to select the one with the shortest period until the maintenance time and warn of the maintenance time. However, it is also possible to calculate the average value of the periods up to different maintenance timings and issue a warning using this average value as the maintenance timing. Then, when the maintenance timing prediction is completed for all the pumps 31, operation end processing is executed.

As described above, according to the pump system according to the second embodiment, it is possible to determine which pump 31 is deteriorated even when three or more pumps 31 are connected in series. Also, the degree of deterioration of each pump 31 can be determined to predict the maintenance timing. Therefore, the pump system does not suddenly stop and can be operated and maintained systematically.

The present invention is not limited to the configurations described in the above embodiments, and various modifications are possible.

In each of the above embodiments, the case of adopting a uniaxial eccentric screw pump as a pump has been described. Alternatively, a rotary pump such as a gear pump or vane pump can be used. By executing failure detection and failure prediction of the pump, for example, in the case of a piston pump, it is possible to diagnose and predict failure of a cylinder sealing member or the like.

In each of the above-described embodiments, a two-stage pump or a multi-stage pump is provided for conveying dehydrated cake, but the objects to be conveyed are not limited to dehydrated cake. This includes items that are difficult to transport.

In each of the above-described embodiments, as the first signal S ₁ , the second signal S ₂ , and the ( _i )th signal Si, the signal output to the inverter of each pump, that is, the rotation speed of each pump is used. parameters can also be used. For example, a signal obtained by detecting the number of revolutions of the motor of each pump with a tachometer or the like may be used.

In each of the above-described embodiments, change tendency data of the ratio S _i /S _k between the (i)th signal S _i and the (k)th signal S _k (the first signal S ₁ and the second signal S ₂ , etc.) stored in the past Although the approximation formula etc. created from the above is used to predict the maintenance timing of the pump, the following method can also be adopted.

That is, the maintenance timing can be predicted using a time series analysis method. In the time-series analysis method, in a pump system, for example, a ratio S2 /S1 is stored every predetermined time. Then, based on the ratio S2/S1 stored for a plurality of times, a future change trend of the ratio S2/S1 is predicted by a time-series analysis method such as an autoregressive model or a moving average model. In this case, the maintenance timing of the pump may be predicted by predicting the timing of reaching the first threshold value CV1 or the second threshold value CV2. According to this, even if various operating conditions of the pump system are different and past data cannot be applied, it can be handled.

In addition, maintenance timing can be predicted using an artificial intelligence function. In this case, the parameters to be used are not limited to the command value to be output to the inverter, but also the temperature, humidity, and weather conditions related to the composition ratio of sewage (for example, if the sediment component increases in the sewage sludge due to heavy rain, the deterioration of the pump is accelerated). forward), etc., that affect delivery by a positive displacement pump. If these parameters are used to learn the change tendency of the ratio S _i /S _k by a method such as deep learning, it becomes possible to predict the maintenance timing of the pump more accurately.

In each of the above embodiments, the pump is PID-controlled so that the pressure in the intermediate pipe 3 is 1/2 of the discharge pressure from the second pump 2. Other methods may be used for control. Alternatively, the transfer amount on the discharge port side of each pump 31 may be measured by a flow meter, and the rotational speed may be PID-controlled when the transfer amount ratio between the pumps 31 deviates from the set range. In short, any pump system may be used as long as it performs control to compensate for a decrease in transfer amount due to deterioration of each pump by correcting the drive control of each pump.

Reference Signs List 1 first pump 2 second pump 3 intermediate pipe 4 first casing 5 first stator 6 first rotor 7 screw rod 8 first conveying section 9 first container section 10 suction section 11 ... Stirrer 12 ... First universal joint 13 ... First motor 14 ... First inverter 15 ... Control device (control means)
DESCRIPTION OF SYMBOLS 16... 2nd casing 17... 2nd stator 18... 2nd rotor 19... 2nd conveyance part 20... 2nd container part 21... Discharge part 22... 2nd universal joint 23... 2nd motor 24... 2nd inverter 25... 2nd DESCRIPTION OF SYMBOLS 1 pressure sensor 26... 2nd pressure sensor 31... Pump 32... Hopper 33... Piping 34... Pressure gauge 35... Flow meter 36... Control device

Claims (16)

a positive displacement pump group including a first pump and a second pump connected in series downstream of the first pump;
a control means for correcting a decrease in transfer amount due to deterioration of at least the second pump by driving and controlling at least one of the first pump and the second pump;
with
The control means controls the ratio S2/S1 between the first signal S1 indicating the driving state of the first pump and the second signal S2 indicating the driving state of the second pump to be greater than or equal to the first threshold value CV1. A pump system that determines that it is time for maintenance of the second pump by satisfying S1≧CV1. a positive displacement pump group including a first pump and a second pump connected in series downstream of the first pump;
a control means for correcting a decrease in transfer amount due to deterioration of at least the first pump by driving and controlling at least one of the first pump and the second pump;
with
The control means controls the ratio S2/S1 between the first signal S1 indicating the driving state of the first pump and the second signal S2 indicating the driving state of the second pump to be equal to or less than a second threshold value CV2. A pump system that determines that it is time for maintenance of the first pump by satisfying S1≦CV2. a positive displacement pump group including a first pump and a second pump connected in series downstream of the first pump;
a control means for correcting a decrease in transfer amount due to deterioration of at least one of the first pump and the second pump by driving and controlling at least one of the first pump and the second pump;
The ratio S2/S1 of the first signal S1 indicating the driving state of the first pump and the second signal S2 indicating the driving state of the second pump indicates that the first pump and the second pump are operating normally. storage means for storing the range of fluctuation in the case and the trend of change until the maintenance timing of the first pump or the second pump;
with
When the ratio S2/S1 changes beyond the fluctuation range, the control means predicts the maintenance timing of the first pump or the second pump based on the changing tendency of the ratio S2/S1. system. The control means predicts the change tendency of the ratio S2/S1 based on the results of storing the ratio S2/S1 multiple times at predetermined time intervals, thereby performing maintenance of the first pump or the second pump. 3. The pump system according to claim 1 or 2, having a time series analysis function for predicting the timing. The control means is artificial intelligence for predicting the maintenance timing of the first pump or the second pump by performing deep learning on the change tendency of the ratio S2/S1 based on the stored result of the ratio S2/S1. 3. Pump system according to claim 1 or 2, having a function. further comprising storage means for storing a first upper limit value UL1 indicating maintenance timing of the first pump;
2. The pump according to claim 1 , wherein said control means determines that said first pump is due for maintenance when said first signal S1 exceeds said first upper limit value UL1 and satisfies S1>UL1. system. further comprising storage means for storing a second upper limit value UL2 indicating maintenance timing of the second pump;
3. The pump according to claim 2 , wherein said control means determines that said second pump is due for maintenance when said second signal S2 exceeds said second upper limit value UL2 and satisfies S2>UL2. system. 8. The control means according to any one of claims 1 to 7, wherein said control means drives and controls said second pump based on an intermediate pressure between said first pump and said second pump and a discharge side pressure of said second pump. or the pump system according to claim 1. a positive displacement pump group consisting of a plurality of pumps connected in series;
a control means for correcting a decrease in transfer amount due to deterioration of the (i) pump among the pumps by driving and controlling the (i) pump;
(i) signal Si indicating the driving state of the (i) pump, (j) signal Sj indicating the driving state of any (j) pump among the pumps, a ratio Si/Sj of the signals, and storage means for storing a threshold value CVk for the ratio Si/Sj;
with
Based on the information stored in the storage means, the control means controls the (i) signal Si indicating the driving state of the (i) pump and the (j) signal Sj indicating the driving state of the (j) pump. ratio Si/Sj is equal to or greater than a threshold value CVk, and the pump system determines that it is time for maintenance of the (i)th pump by satisfying Si/Sj≧CVk. 10. The pump system according to claim 9, wherein said control means determines maintenance timing for all combinations of said two pumps. 11. The pump system according to claim 10, wherein said control means sets the maintenance period of each pump to the period determined to be the shortest. The storage means further includes (i) a signal Si indicating the drive state of the (i) pump and (j) signal Si indicating the drive state of the (j) pump when the pump is in normal operation. storing the variation range of the ratio Si/Sj of the signal Sj and the trend of change until the (i)th pump reaches the maintenance time;
10. From claim 9, wherein when the ratio Si/Sj changes beyond the fluctuation range, the control means predicts the maintenance timing of the (i)th pump based on the change tendency of the ratio Si/Sj. 12. Pump system according to any one of clause 11. The control means judges whether or not the (i)th signal Si indicating the drive state of the (i)th pump satisfies Si≤SR, which is within a set range. 13. A pump system according to any one of claims 9 to 12, wherein the pump system determines that it is time for maintenance of the pump. The control means controls the ratio S1/Sj between the (i)th signal Si indicating the driving state of the (i)th pump and the (j)th signal Sj indicating the driving state of the (j)th pump at predetermined time intervals. of claims 9 to 13, having a time series analysis function of predicting the maintenance timing of the (i)th pump by predicting the change tendency of the ratio Si/Sj based on the results stored a plurality of times in the A pump system according to any one of the preceding claims. The control means stores the result of storing the ratio Si/Sj of the (i)th signal Si indicating the driving state of the (i)th pump and the (j)th signal Sj indicating the driving state of the (j)th pump. 14. The artificial intelligence function that predicts the maintenance timing of the (i)th pump by deep learning the change tendency of the ratio Si / Sj based on pump system. 16. A pumping system according to any preceding claim, wherein each pump is a single eccentric screw pump.

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