WO2015137126A1 - Magnetic levitation-type pump device, method for estimating viscosity of fluid by magnetic levitation-type pump device, and method for estimating flow rate of fluid by magnetic levitation-type pump device - Google Patents

Abstract

The present invention makes it possible to more accurately estimate fluid viscosity without being constrained with respect to the structure of a device. A magnetic levitation-type pump device (100) for transferring a fluid (L) by magnetically levitating and rotating an impeller (104), wherein the magnetic levitation-type pump device (100) is provided with: a magnetic bearing unit (101) for supporting the impeller in a non-contact manner by magnetic force; an applied current control unit (154) for controlling a current applied to electromagnets (116) provided to the magnetic bearing unit; a displacement sensor (118) for detecting displacement of the impeller; a calculation unit (158) for calculating the phase difference between the impeller displacement and an alternating current, and/or the amplitude ratio between the impeller displacement and the alternating current, the impeller displacement being due to the vibration of the impeller and being detected by the displacement sensor, when the applied current control unit controls the applied current so as to cause the alternating current in a predetermined frequency range to overlap with an excitation current to the electromagnets; and a viscosity estimation unit (160) for estimating the viscosity of the fluid on the basis of the phase difference and/or amplitude ratio calculated at the calculation unit.

Description

Magnetic levitation pump device, fluid viscosity estimation method using magnetic levitation pump device, and fluid flow rate estimation method using magnetic levitation pump device

The present invention relates to a magnetic levitation pump device in which an impeller supported in a non-contact manner on a magnetic bearing portion is levitated and rotated by electromagnetic force, a fluid viscosity estimation method using a magnetic levitation pump device, and a fluid using a magnetic levitation pump device The present invention relates to a flow rate estimation method. This application claims priority on the basis of Japanese Patent Application No. 2014-047493 filed on March 11, 2014 in Japan, and is incorporated herein by reference. Is done.

Magnetic levitation type that moves various fluids such as gas and liquid by rotating an impeller that is supported in a non-contact manner by magnetic force in medical equipment such as blood pumps, semiconductors, and food manufacturing fields. A pump device is used. In particular, when the fluid to be transferred is a liquid, the viscosity affects the fluid transfer performance of the pump device. Therefore, in order to maintain the performance, it is necessary to estimate and grasp the viscosity. .

In order to estimate the viscosity of the fluid to be transferred by the magnetic levitation pump device, the torque increases as the viscosity increases, so that the viscosity is conventionally estimated from the motor torque for rotating the impeller. However, in order to estimate the viscosity from the motor torque, it has been difficult to install a torque meter in the pump device in view of the size and cost of the device. For this reason, the viscosity is estimated by indirectly measuring the torque from the current and power consumption of the motor.

However, in the viscosity estimation based on the indirect measurement of torque based on the current and power consumption, bearing loss and the like are an error factor, and it is difficult to estimate the viscosity with high accuracy. As a centrifugal liquid pump device having a viscosity calculation function that can easily and reliably calculate the liquid viscosity without using a special viscometer, Patent Document 1 discloses that the impeller is floated from the rotation axis center to the vicinity of the housing wall. A technique for estimating the viscosity from the amount of change in motor current at that time by shifting is disclosed.

Japanese Patent Laid-Open No. 11-76394

In order to maintain a stable operation of the magnetic levitation pump that supports the impeller in a non-contact manner with the magnetic bearing, it is necessary to prevent the impeller from being damaged or worn when disturbances occur. It is necessary to avoid contact between the housing for housing the impeller and the impeller. For this reason, it is preferable that a certain gap is provided between the impeller and the housing. However, in the centrifugal liquid pump device disclosed in Patent Document 1, it is difficult to measure the torque change due to the motor current change unless the gap between the impeller and the housing is sufficiently narrow. That is, in order to increase the accuracy of fluid viscosity estimation, there are significant structural restrictions on the pump device.

The present invention has been made in view of the above problems, and a new and improved magnetic levitation pump device capable of estimating the viscosity of a fluid more easily and reliably without being restricted by the structure of the device, It is an object of the present invention to provide a fluid viscosity estimation method using a magnetic levitation pump device and a fluid flow rate estimation method using a magnetic levitation pump device.

One aspect of the present invention is a magnetically levitated pump device that transfers the fluid while magnetically levitating and rotating an impeller in a housing having a fluid inflow portion and an outflow portion, and is non-contact with the impeller by magnetic force A rotary drive unit coupled to the impeller to rotate the impeller, a magnetic bearing unit supporting the impeller in a non-contact manner by the magnetic force, and a position facing the permanent magnet built in the rotor of the impeller of the magnetic bearing unit. An applied current control unit that controls an applied current to the electromagnet provided, a current sensor that detects the magnitude of the applied current, a displacement sensor that detects displacement of the impeller, and the applied current control unit within a predetermined frequency range The impeller detected by the displacement sensor when the applied current is controlled so as to be superimposed on the excitation current to the electromagnet for a predetermined time. A calculation unit that calculates at least one of a phase difference between the impeller displacement due to vibration and the alternating current or an amplitude ratio between the impeller displacement and the alternating current, and at least one of the phase difference or the amplitude ratio calculated by the calculation unit And a viscosity estimation unit that estimates the viscosity of the fluid.

According to one aspect of the present invention, the impeller is forcibly vibrated by applying an alternating current so as to be superimposed on the exciting current applied to the electromagnet of the magnetic bearing portion for a predetermined time. Based on the phase difference and amplitude ratio of the alternating current, the viscosity of the fluid can be estimated easily and accurately.

At this time, according to an aspect of the present invention, the applied current control unit is configured to apply a frequency at which the impeller can vibrate around a levitation target position when the alternating current is applied and superimposed on the excitation current, and the impeller Alternatively, an alternating current having an amplitude within a range where the housing does not contact may be applied.

In this way, since the vibration of the impeller can be suppressed to a slight vibration, the viscosity of the fluid to be transferred can be reliably estimated while maintaining a stable operation state of the magnetic levitation pump device.

Further, in one aspect of the present invention, the frequency may be a value close to a value calculated by the following equation.

In this way, when an alternating current is applied, the impeller can be slightly vibrated in a range where the impeller and the housing do not contact each other, so that the viscosity of the fluid to be transferred is maintained while maintaining a stable operation state of the magnetic levitation pump device. Can be reliably estimated.

Moreover, in one aspect of the present invention, the viscosity estimation unit is based on prior experimental data relating to the relationship between the phase difference and the viscosity, or a relational expression between the phase difference and the viscosity obtained theoretically in advance. The viscosity may be estimated.

In this way, the viscosity of the fluid can be accurately estimated based on the phase difference of the impeller displacement caused by the impeller vibration generated by applying the alternating current superimposed on the exciting current.

Moreover, in one aspect of the present invention, the impeller may have any shape of a centrifugal type, an axial flow type, or a diagonal flow type.

In this way, it can be applied to a magnetic levitation type continuous flow pump regardless of centrifugal type, axial flow type or mixed flow type.

In one aspect of the present invention, the flow rate of the fluid is estimated based on at least one of the torque, current value, power consumption, and rotation speed of the rotation drive unit and the viscosity estimated by the viscosity estimation unit. It is good also as providing the flow volume estimation part to perform.

In this way, accuracy in estimating the flow rate of the fluid is improved by compensation with the estimated viscosity.

According to another aspect of the present invention, there is provided a fluid viscosity estimation method using a magnetic levitation pump device that transfers a fluid while magnetically levitating and rotating an impeller in a housing having a fluid inflow portion and an outflow portion. An alternating current application step of applying and superimposing an alternating current in a predetermined frequency range on an exciting current applied to an electromagnet provided at a position facing a permanent magnet built in the rotor of the impeller, and after applying the alternating current, An impeller displacement detecting step for detecting an impeller displacement due to the vibration of the impeller, a recording step for recording at least one of a phase or an amplitude of the impeller displacement due to the vibration, a phase difference or an amplitude ratio of the impeller displacement and the alternating current Based on at least one of the phase difference or the amplitude ratio, and a calculation step for calculating at least one of the phase difference and the amplitude ratio. Characterized in that it comprises a and a viscosity estimation step of estimating.

According to another aspect of the present invention, the impeller is intentionally slightly vibrated by applying an alternating current so as to be superimposed on the exciting current applied to the electromagnet of the magnetic bearing portion for a predetermined time, and the impeller displacement The viscosity of the fluid can be estimated easily and accurately based on the phase difference and amplitude ratio of the alternating current.

Still another aspect of the present invention is a method for estimating a fluid flow rate by a magnetic levitation pump device that transfers a fluid while magnetically levitating and rotating an impeller in a housing having a fluid inflow portion and an outflow portion. An alternating current applying step of applying an alternating current in a predetermined frequency range to superimpose an exciting current applied to an electromagnet provided at a position facing a permanent magnet built in the rotor of the impeller, and after applying the alternating current An impeller displacement detecting step for detecting an impeller displacement due to the vibration of the impeller, a recording step for recording at least one of a phase or an amplitude of the impeller displacement due to the vibration, a phase difference or an amplitude ratio between the impeller displacement and the alternating current And calculating the fluid based on at least one of the phase difference and the amplitude ratio. Based on the viscosity estimation step of estimating the viscosity, at least one of the torque, current value, power consumption, and rotation speed of the rotation drive unit that rotates the impeller, and the viscosity estimated in the viscosity estimation step, the fluid And a flow rate estimating step for estimating the flow rate of.

According to still another aspect of the present invention, the accuracy in estimating the fluid flow rate is improved by utilizing the viscosity estimated by the magnetic levitation pump device.

At this time, in still another aspect of the present invention, in the flow rate estimation step, the estimated flow rate obtained from the torque of the rotation drive unit and the rotation speed is compensated by the viscosity estimated in the viscosity estimation step. It is good also as estimating the said flow volume by.

In this way, it is possible to accurately estimate the flow rate of the fluid to be measured by compensating with the estimated viscosity.

As described above, according to the present invention, the viscosity of the fluid can be estimated more easily and reliably with high accuracy without adding new hardware and without being restricted by the structure of the apparatus. In addition, the flow rate of the fluid can be estimated more easily and reliably using the viscosity.

FIG. 1 is a block diagram showing a schematic configuration of a magnetic levitation pump apparatus according to an embodiment of the present invention. FIG. 2 is a flowchart showing an outline of a fluid viscosity estimation method by the magnetic levitation pump device according to the embodiment of the present invention. FIG. 3 is a flowchart showing an outline of another aspect of the fluid viscosity estimation method by the magnetic levitation pump device according to the embodiment of the present invention. 4A to 4D are examples of waveform diagrams of alternating current applied when the viscosity of the fluid is estimated by the magnetic levitation pump device according to the embodiment of the present invention. 5A to 5E are explanatory views showing a configuration example of an impeller provided in a magnetic levitation pump device according to an embodiment of the present invention. FIG. 6 is a block diagram showing a schematic configuration of a magnetic levitation pump device according to another embodiment of the present invention. FIG. 7 is a flowchart showing an outline of a method for estimating the viscosity and flow rate of a fluid by a magnetic levitation pump device according to another embodiment of the present invention. FIG. 8 is a flowchart showing an outline of another aspect of the fluid viscosity and flow rate estimation method by the magnetic levitation pump device according to another embodiment of the present invention. FIG. 9 is an explanatory diagram showing the phase and amplitude relationship between the waveform of the impeller displacement and the waveform of the applied current in an example of fluid viscosity estimation by the magnetic levitation pump device according to the embodiment of the present invention. FIG. 10 is an explanatory diagram showing the relationship between the amplitude ratio and phase difference between the waveform of the impeller displacement and the waveform of the applied current and the frequency of the applied current in this example. FIG. 11 is an explanatory diagram showing the relationship between the viscosity and the phase difference at a vibration frequency of 70 Hz in this example. FIG. 12 is an explanatory diagram showing the relationship between the flow rate of the fluid and the phase difference at the vibration frequency of 70 Hz in this embodiment. FIG. 13 is an explanatory diagram showing the relationship between the estimated viscosity and the actually measured viscosity in this example. FIG. 14 is an explanatory diagram showing the relationship between the actually measured flow rate and the estimated flow rate in an example of fluid flow rate estimation by the magnetic levitation pump device according to another embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail. The present embodiment described below does not unduly limit the contents of the present invention described in the claims, and all the configurations described in the present embodiment are essential as means for solving the present invention. Not necessarily.

(First embodiment)
First, the configuration of a magnetic levitation pump device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a magnetic levitation pump apparatus according to an embodiment of the present invention.

The magnetic levitation pump apparatus 100 according to an embodiment of the present invention is configured to drive the motor 108 by coupling the drive shaft 113 of the motor 108 serving as a drive source (rotation drive unit) and the impeller 104 in a non-contact manner by magnetic coupling. It is a non-contact type magnetic levitation type continuous flow pump that transmits force. In addition, the magnetic levitation pump apparatus 100 according to the present embodiment applies the excitation current to the electromagnet 116 of the magnetic bearing unit 101 so that the center of the magnetically levitated impeller 104 rotates when the impeller 104 rotates. Position control is performed so as to rotate at the flying target position that coincides with A1.

In this embodiment, the impeller 104 is a centrifugal impeller that is magnetically levitated in the housing 102 and is coupled in a non-contact manner with the drive shaft 113 of the motor 108 by magnetic coupling and rotates while magnetically levitating in the housing 102. . As shown in FIG. 1, the center of the bottom surface of the rotor 106 of the impeller 104 is a concave portion 106 b, and the concave portion 106 b is opposed to the convex portion 102 b 1 provided on the central side of the bottom surface 102 b of the housing 102. ing.

The fluid L inflow portion 102 c is provided on the top side of the housing 102 that houses the impeller 104, and the fluid L outflow portion 102 d is provided at any part of the side wall 102 a of the housing 102. For this reason, when the impeller 104 rotates in the housing 102 while magnetically levitating, the fluid L is transferred from the inflow portion 102c to the outflow portion 102d.

In this embodiment, the magnetic bearing portion 101 supports the impeller 104 in a non-contact manner by a magnetic force. In the magnetic bearing portion 101, an electromagnet 116 is provided at a position facing the permanent magnet 110 built in the outer peripheral surface 106 a side of the rotor 106 of the impeller 104. By applying an exciting current to the electromagnet 116, the center of the impeller 104 is adjusted so as to be arranged on the rotation center axis A1.

That is, with respect to the horizontal direction, the position of the impeller 104 is controlled by applying an exciting current to the electromagnet 116. On the other hand, with respect to the vertical direction, the impeller 104 is passively maintained in the floating state by the restoring force acting in the vertical direction of the magnetic circuit constituting the magnetic coupling without being controlled in position.

Furthermore, in the present embodiment, a motor 108 serving as a drive source for the impeller 104 is provided in the casing 122 of the magnetic bearing portion 101, and a permanent magnet 114 is provided on the outer peripheral surface on the front end side of the drive shaft 113 of the motor 108. ing. And the permanent magnet 112 which acts on the said permanent magnet 114 and attractive force is provided in the internal peripheral surface 106b1 of the recessed part 106b of the rotor 106 of the impeller 104. As shown in FIG. When these permanent magnets 112 and 114 are coupled by magnetic coupling, the driving force of the motor 108 is transmitted to the impeller 104 in a non-contact manner. The driving of the motor 108 is controlled by a motor control unit 164 provided in a control unit 150 that performs various controls of the magnetic levitation pump device 100.

In the present embodiment, the applied current to the electromagnet 116 of the magnetic bearing unit 101 is controlled by the applied current control unit 154. Specifically, the applied current control unit 154 feeds back a signal of the displacement sensor 120 that detects the displacement of the impeller 104 to the calculation unit 152 of the control unit 150 so that the impeller 104 floats on the rotation axis center A1. An appropriate current value is calculated and controlled to be supplied to the electromagnet 116. For example, when the position of the impeller 104 is displaced due to disturbance or the like, the applied current control unit 154 appropriately adjusts the magnitude of the excitation current so that the impeller 104 returns to the floating target position that can rotate about the rotation axis center A1. Control to do.

The displacement sensor 120 is a sensor that is provided, for example, between any of a plurality of electromagnets 116 arranged in an annular shape and detects the position of the impeller 104 by detecting the outer peripheral surface 106a of the rotor 106, and is an eddy current sensor. Etc. The magnitude of the applied current is detected by a current sensor 118 provided between the electromagnet 116 and the applied current control unit 154. The exciting current applied to the electromagnet 116 is adjusted by the applied current adjusting unit 162 such as an amplifier or an inverter under the control of the applied current control unit 154.

As a result of intensive studies to achieve the above-described object of the present invention, the present inventor has intentionally applied an alternating current to the electromagnet 116 provided in the magnetic bearing portion 101 of the magnetic levitation pump device 100 of the present embodiment. It has been found that the phase difference θ between the impeller displacement generated when the impeller 104 is forcibly vibrated by application and the applied alternating current is correlated with the viscosity μ of the working fluid. It was also found that there is a correlation between the amplitude μ of the impeller displacement at that time and the amplitude ratio a / b of the amplitude b of the applied alternating current and the viscosity μ.

The magnetic levitation pump device 100 of the present embodiment realized the estimation of the fluid viscosity μ using the principle described above. Here, details of the CPU (arithmetic unit) 152 that controls the above-described control of the magnetic levitation pump device 100 of the present embodiment will be described.

The CPU 152 has a function of controlling the operation of each component included in the magnetic levitation pump device 100 in accordance with various programs stored in the storage unit 166 such as a ROM. In addition, the CPU 152 has a function of appropriately storing necessary data and the like in a RAM (not shown) that temporarily stores data when executing these various processes.

In the present embodiment, the CPU 152 includes an applied current control unit 154, an impeller displacement recording unit 156, a calculation unit 158, and a viscosity estimation unit 160, as shown in FIG.

The applied current control unit 154 has a function of controlling the applied current to the electromagnet 116 of the magnetic bearing unit 101 as described above. In the present embodiment, when the applied current control unit 154 estimates the viscosity μ of the fluid L, the applied current control unit 154 superimposes an alternating current in a predetermined frequency range on an excitation current to the electromagnet 116 for a predetermined time (for example, several seconds). And has a function of controlling the applied current so as to be applied.

Specifically, when the applied current control unit 154 applies an alternating current and superimposes the excitation current on the excitation current, the applied current control unit 154 has a frequency at which the impeller 104 can vibrate around the floating target position, and a range where the impeller 104 and the housing 102 do not contact each other. An alternating current having an amplitude within the range is applied. The frequency f is preferably a value close to the value calculated by the following equation (1).

Note that Kx described in the above formula (1) is “negative rigidity (N / m) expressed in the magnetic bearing portion 101”, and M is “additional mass due to the fluid L added to the mass of the impeller 104”. Value (kg) ". Here, the “additional mass” indicates a mass corresponding to an increase in the apparent weight when the impeller 104 is placed in the liquid, and is a value that varies depending on the liquid density. For example, when the liquid is blood, the additional mass is about ten times the mass of the impeller 104.

Thus, by applying the alternating current in the frequency range described above, the vibration of the impeller 104 can be suppressed to a slight vibration in a range where the impeller 104 and the housing 102 do not contact each other. For this reason, it is possible to reliably estimate the viscosity μ of the fluid L to be transferred while maintaining a stable operation state of the magnetic levitation pump device 100.

The impeller displacement recording unit 156 has a function of creating and recording a function curve while plotting the impeller displacement detected by the displacement sensor 120. The recording data plotted by the impeller displacement recording unit 156 is used to calculate the phase difference θ or the amplitude ratio a / b used for estimating the viscosity of the fluid L.

The calculation unit 158 has a function of calculating data necessary for control of each component of the magnetic levitation pump apparatus 100 based on detection data of the current sensor 118 and the displacement sensor 120 and the like. In the present embodiment, the calculation unit 158 includes the phase difference θ between the impeller displacement and the alternating current detected by the vibration of the impeller 104 detected by the displacement sensor 120, or the amplitude ratio a / b between the amplitude a of the impeller displacement and the amplitude b of the alternating current. Has a function of calculating at least one of the following. That is, when the applied current control unit 154 controls the applied current so that the applied current is superimposed on the excitation current to the electromagnet 116, the calculating unit 158 has at least one of the phase difference θ and the amplitude ratio a / b. It has a function to calculate.

The viscosity estimating unit 160 has a function of estimating the viscosity μ of the fluid L based on at least one of the phase difference θ and the amplitude ratio a / b calculated by the calculating unit 158. In the present embodiment, when the viscosity estimating unit 160 estimates the viscosity of the fluid L based on the phase difference θ, for example, the phase difference stored in the storage unit 166 or the like is used to accurately estimate the viscosity. The viscosity μ is estimated based on prior experimental data relating to the relationship between θ and the viscosity μ of the fluid, or based on a relational expression between the phase difference θ and the viscosity μ that is theoretically obtained in advance.

As described above, in the present embodiment, the impeller 104 is forcibly microvibrated by applying an alternating current intentionally superimposed on the exciting current applied to the electromagnet 116 of the magnetic bearing portion 101 for a predetermined time. . Accordingly, the viscosity μ of the fluid L can be easily and accurately estimated based on the phase difference θ between the impeller displacement generated by the minute vibration and the alternating current and the amplitude ratio a / b. In addition, the viscosity μ of the fluid L can be estimated more easily and reliably without adding new hardware such as a torque meter as in the prior art and without being restricted by the structure of the apparatus.

Next, a fluid viscosity estimation method using a magnetic levitation pump device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a flowchart showing an outline of a fluid viscosity estimation method by a magnetic levitation pump apparatus according to an embodiment of the present invention, and FIG. 3 is a magnetic levitation pump apparatus according to an embodiment of the present invention. It is a flowchart which shows the outline of the other aspect of the viscosity estimation method of the fluid by A. 2 shows a flow of a method for estimating the viscosity μ based on the phase difference θ, and FIG. 3 shows a flow of a method for estimating the viscosity μ based on the amplitude ratio a / b.

In the fluid viscosity estimation method by the magnetic levitation pump apparatus 100 of the present embodiment, first, an alternating current in a predetermined frequency range is applied to the excitation current applied to the electromagnet 116 provided in the magnetic bearing unit 101 for a predetermined time (for example, several seconds). ) And superimposed on the excitation current (AC current application step S11). Thus, in the present embodiment, the impeller 104 is forcibly vibrated by intentionally applying an alternating current for a predetermined time.

At that time, as described above, an alternating current having a frequency f at which the impeller can vibrate around the floating target position and an amplitude b within a range where the impeller 104 and the housing 102 do not contact each other is applied. That is, it is necessary to select an appropriate frequency f and amplitude b so that the vibration of the impeller 104 does not contact the impeller 104 and the housing 102 around the floating target position.

If the frequency of the alternating current applied is too high, even if the amplitude of the alternating current is maximized, the impeller 104 does not respond and does not vibrate, so the viscosity estimation method according to this embodiment cannot be performed. For this reason, in the low frequency region (for example, 400 Hz or less) where the impeller 104 vibrates, the impeller 104 and the housing 102 are adjusted so as not to contact each other by appropriately adjusting the amplitude of the alternating current. That is, in order to estimate the viscosity of the fluid L by the viscosity estimation method according to the present embodiment, the frequency f of the alternating current to be applied is selected to be a frequency that is low enough to obtain the vibration amplitude a of the impeller 104, The amplitude b of the alternating current needs to be adjusted within a range where the impeller 104 and the housing 102 do not contact each other.

Note that the alternating current applied here may be an alternating current having a predetermined period in which the current value periodically fluctuates, and the waveform thereof is, for example, a sine wave shown in FIG. 4A or a rectangle shown in FIG. 4B. A wave, a triangular wave shown in FIG. 4C, and a sawtooth wave shown in FIG. 4D are applicable.

After the alternating current is applied, the displacement of the impeller due to the vibration of the impeller 104 is detected by the displacement sensor 120 (impeller displacement detection step S12). Then, the phase of the impeller displacement caused by the vibration of the impeller 104 generated by the application of the alternating current is plotted and recorded (recording step S13). Thereafter, the phase difference θ between the impeller displacement and the alternating current is calculated (calculation step S14), and the viscosity μ of the fluid L is estimated based on the phase difference θ (viscosity estimation step S15).

On the other hand, when detecting the viscosity μ with the amplitude ratio a / b, as shown in FIG. 3, the vibration of the impeller 104 generated by the application of the alternating current after the alternating current application step S21 and the impeller displacement detection step S22. The amplitude a of the impeller displacement due to is plotted and recorded (recording step S23). Then, the amplitude ratio a / b between the impeller displacement and the alternating current is calculated (calculation step S24), and the viscosity μ of the fluid L is estimated based on the amplitude ratio a / b (viscosity estimation step S25).

In this embodiment, the viscosity μ of the fluid L is estimated using the phase difference θ or the amplitude ratio a / b. However, if at least one of them is used, the viscosity μ can be estimated. Both may be used together to estimate the viscosity μ of the fluid L with higher accuracy.

Thus, in the present embodiment, during the normal operation of the magnetic levitation pump device 100, the excitation current to the electromagnet 116 is calculated so that the impeller 104 does not shake from the target position (center of rotation axis, etc.). . On the other hand, when estimating the viscosity μ of the fluid L, the impeller 104 is forcibly vibrated by superimposing an alternating current having a constant frequency f on the excitation current for several seconds. Then, during the forced vibration of the impeller 104, the phase difference θ or the amplitude ratio a / b between the alternating current I of the frequency f and the impeller displacement X is calculated. As described above, since the phase difference θ and the amplitude ratio a / b change depending on the viscosity μ of the fluid, the relationship between θ and μ obtained experimentally in advance or the theoretically obtained θ and μ From the relational expression, the fluid viscosity μ is estimated.

For this reason, the viscosity estimation method by the magnetic levitation pump apparatus 100 of the present embodiment can easily estimate the viscosity μ of the fluid L without adding new hardware. Also, the viscosity estimation method by the magnetic levitation pump device 100 of the present embodiment is less dependent on the flow rate and does not need to cut off the flow rate, unlike the conventional method using the motor torque for viscosity estimation. Since there is no influence of loss, the fluid viscosity μ can be accurately estimated. Furthermore, the viscosity estimation method using the magnetically levitated pump device 100 according to the present embodiment does not affect the measurement accuracy of the viscosity μ even if the gap between the impeller 104 and the housing 102 is large in principle. Accurate viscosity estimation is possible without being restricted by the above.

In addition, in one Embodiment of this invention mentioned above, although applied to the magnetic levitation type pump apparatus 100 provided with the centrifugal impeller 104 as shown in the top view of FIG. 5A and the side view of FIG. 5B, FIG. The present invention is also applicable to a magnetic levitation pump apparatus including an axial flow type impeller 124 as shown in the plan view and the side view of FIG. 5D and a mixed flow type impeller 134 as shown in the side view of FIG. 5E. That is, the magnetic levitation pump device 100 of this embodiment can be applied to a magnetic levitation type continuous flow pump regardless of whether it is a centrifugal type, an axial flow type, or a diagonal flow type. In other words, the viscosity can be estimated in the same procedure as in the present embodiment even in the case of an axial flow type or mixed flow type impeller shape.

Moreover, the viscosity estimation method by the magnetic levitation pump device 100 of the present embodiment described above can be applied to various fields. For example, in a conventional circulation system such as an artificial artificial heart that is difficult to install a flow meter, there has been extensive research on estimating the flow rate from motor torque, etc., but the error greatly increases or decreases depending on the working fluid viscosity. The estimated viscosity value obtained by the viscosity estimation method using the magnetic levitation pump device 100 of this embodiment can be used for error correction in flow rate estimation.

Furthermore, the state of the working fluid may be applied to online monitoring using the estimated viscosity value itself. For example, it can be applied to blood coagulation monitoring such as blood clot detection and prediction in blood pumps and artificial hearts, and quality control of ultrapure water in semiconductor and food manufacturing. That is, it can be applied as a magnetic levitation type continuous flow blood pump for extracorporeal circulation, a magnetic levitation type artificial heart for implantation in the body, and an ultra-clean magnetic levitation type pump for semiconductor manufacturing and food manufacturing.

(Second Embodiment)
Next, the configuration of a magnetic levitation pump device according to another embodiment of the present invention will be described with reference to the drawings. FIG. 6 is a block diagram showing a schematic configuration of a magnetic levitation pump device according to another embodiment of the present invention.

In a magnetic levitation pump device 200 according to another embodiment of the present invention, a drive shaft 213 and an impeller 204 of a motor 208 serving as a drive source (rotation drive unit) are coupled in a non-contact manner by magnetic coupling. It is a non-contact type magnetic levitation type continuous flow pump that transmits the driving force of the motor. In addition, the magnetic levitation pump device 200 of the present embodiment applies the excitation current to the electromagnet 216 of the magnetic bearing unit 201 to rotate the central axis of the magnetically levitated impeller 204 when the impeller 204 is driven to rotate. Position control is performed so as to rotate at the flying target position that coincides with A2.

In the present embodiment, the impeller 204 is a centrifugal impeller that rotates while being magnetically levitated in the housing 202 while being magnetically levitated in the housing 202 and coupled in a non-contact manner with the drive shaft 213 of the motor 208 by magnetic coupling. . As shown in FIG. 6, the center of the bottom surface of the rotor 206 of the impeller 204 is a concave portion 206 b, and is configured to face the convex portion 202 b 1 provided on the central side of the bottom surface 202 b of the housing 202. ing.

The fluid L inflow portion 202 c is provided on the top side of the housing 202 that houses the impeller 204, and the fluid L outflow portion 202 d is provided at any part of the side wall 202 a of the housing 202. For this reason, when the impeller 204 rotates in the housing 202 while magnetically levitating, the fluid L is transferred from the inflow portion 202c to the outflow portion 202d.

In this embodiment, the magnetic bearing unit 201 supports the impeller 204 in a non-contact manner by a magnetic force. The magnetic bearing portion 201 is provided with an electromagnet 216 at a position facing the permanent magnet 210 built in the outer peripheral surface 206 a side of the rotor 206 of the impeller 204. By applying an exciting current to the electromagnet 216, the center of the impeller 204 is adjusted so as to be arranged on the rotation center axis A2.

That is, the position of the impeller 204 is controlled by applying an exciting current to the electromagnet 216 in the horizontal direction. On the other hand, with respect to the vertical direction, the impeller 204 is passively maintained in the floating state by the restoring force acting in the vertical direction of the magnetic circuit constituting the magnetic coupling without being controlled in position.

Furthermore, in the present embodiment, a motor 208 serving as a drive source for the impeller 204 is provided in the casing 222 of the magnetic bearing unit 201, and a permanent magnet 214 is provided on the outer peripheral surface on the front end side of the drive shaft 213 of the motor 208. ing. A permanent magnet 212 that acts an attractive force with the permanent magnet 214 is provided on the inner peripheral surface 206 b 1 of the recess 206 b of the rotor 206 of the impeller 204. These permanent magnets 212 and 214 are coupled by a magnetic coupling, whereby the driving force of the motor 208 is transmitted to the impeller 204 in a non-contact manner. Driving of the motor 208 is controlled by a motor control unit 264 provided in a control unit 250 that performs various controls of the magnetic levitation pump device 200.

In this embodiment, the applied current to the electromagnet 216 of the magnetic bearing unit 201 is controlled by the applied current control unit 254. Specifically, the applied current control unit 254 feeds back a signal of the displacement sensor 220 that detects the displacement of the impeller 204 to the calculation unit 252 of the control unit 250 so that the impeller 204 floats to the rotation axis center A2. An appropriate current value is calculated and controlled to be supplied to the electromagnet 216. For example, when the position of the impeller 204 is shifted due to a disturbance or the like, the applied current control unit 254 appropriately adjusts the magnitude of the excitation current so that the impeller 204 returns to the levitation target position that can rotate around the rotation axis A2. Control to do.

The displacement sensor 220 is a sensor that is provided, for example, between any of the plurality of electromagnets 216 arranged in an annular shape, and detects the position of the impeller 204 by detecting the outer peripheral surface 206a of the rotor 206, and is an eddy current sensor. Etc. The magnitude of the applied current is detected by a current sensor 218 provided between the electromagnet 216 and the applied current control unit 254. The exciting current applied to the electromagnet 216 is adjusted by the applied current adjusting unit 262 such as an amplifier or an inverter under the control of the applied current control unit 254.

As a result of intensive studies in order to achieve the above-described object of the present invention, the present inventor intentionally applied an alternating current to the electromagnet 216 provided in the magnetic bearing portion 201 of the magnetic levitation pump device 200 of the present embodiment. It has been found that the phase difference θ between the impeller displacement generated when the impeller 204 is forcibly vibrated by application and the applied alternating current is correlated with the viscosity μ of the working fluid. It was also found that there is a correlation between the amplitude μ of the impeller displacement at that time and the amplitude ratio a / b of the amplitude b of the applied alternating current and the viscosity μ. Furthermore, the present inventor has found that the flow rate can be estimated with higher accuracy by using the estimated viscosity value obtained by the viscosity estimation method by the magnetic levitation pump apparatus 200 of the present embodiment for error correction of the flow rate estimation.

The magnetic levitation pump device 200 of the present embodiment realized the estimation of the fluid viscosity μ using the principle described above. Here, details of the CPU (arithmetic unit) 252 that controls the above-described control of the magnetic levitation pump device 200 of the present embodiment will be described.

The CPU 252 has a function of controlling the operation of each component provided in the magnetic levitation pump device 200 according to various programs stored in the storage unit 266 such as a ROM. Further, the CPU 252 has a function of appropriately storing necessary data and the like in a RAM (not shown) that temporarily stores data when executing these various processes.

In this embodiment, the CPU 252 includes an applied current control unit 254, an impeller displacement recording unit 256, a calculation unit 258, a viscosity estimation unit 260, and a flow rate estimation unit 261, as shown in FIG.

The applied current control unit 254 has a function of controlling the applied current to the electromagnet 216 of the magnetic bearing unit 201 as described above. In the present embodiment, when the applied current control unit 254 estimates the viscosity μ of the fluid L, the applied current control unit 254 superimposes an alternating current in a predetermined frequency range on an excitation current to the electromagnet 216 for a predetermined time (for example, several seconds). And has a function of controlling the applied current so as to be applied.

Specifically, the applied current control unit 254 applies a frequency at which the impeller 204 can vibrate around the floating target position when applying an alternating current and superimposing it with the excitation current, and a range where the impeller 204 and the housing 202 do not contact each other. An alternating current having an amplitude within the range is applied. The frequency f is preferably a value close to the value calculated by the above-described equation (1), as in the first embodiment.

Thus, by applying the alternating current in the frequency range described above, the vibration of the impeller 204 can be suppressed to a slight vibration in a range where the impeller 204 and the housing 202 do not contact each other. Therefore, it is possible to reliably estimate the viscosity μ of the fluid L to be transferred while maintaining a stable operation state of the magnetic levitation pump device 200.

The impeller displacement recording unit 256 has a function of creating and recording a function curve while plotting the impeller displacement detected by the displacement sensor 220. The recorded data plotted by the impeller displacement recording unit 256 is used to calculate the phase difference θ or the amplitude ratio a / b used for estimating the viscosity of the fluid L.

The calculation unit 258 has a function of calculating data necessary for control of each component of the magnetic levitation pump device 200 based on detection data of the current sensor 218 and the displacement sensor 220 and the like. In the present embodiment, the calculation unit 258 includes the phase difference θ between the impeller displacement detected by the displacement sensor 220 due to the vibration of the impeller 204 and the alternating current, or the amplitude ratio a / b between the impeller displacement amplitude a and the alternating current amplitude b. Has a function of calculating at least one of the following. That is, the calculation unit 258 controls at least one of the phase difference θ and the amplitude ratio a / b when the applied current control unit 254 controls the applied current so that the alternating current is superimposed on the excitation current to the electromagnet 216. It has a function to calculate.

The viscosity estimation unit 260 has a function of estimating the viscosity μ of the fluid L based on at least one of the phase difference θ and the amplitude ratio a / b calculated by the calculation unit 258. In the present embodiment, when the viscosity estimating unit 260 estimates the viscosity of the fluid L based on the phase difference θ, for example, the phase difference stored in the storage unit 266 or the like is used to accurately estimate the viscosity. The viscosity μ is estimated based on prior experimental data relating to the relationship between θ and the viscosity μ of the fluid, or based on a relational expression between the phase difference θ and the viscosity μ that is theoretically obtained in advance.

The flow rate estimation unit 261 has a function of estimating the flow rate of the fluid L based on at least one of the torque, current value, power consumption, and rotation speed of the motor 208 and the viscosity of the fluid L estimated by the viscosity estimation unit 260. Have. In the present embodiment, the flow rate estimation unit 261 uses the torque of the motor 208 measured by a known torque meter 224 installed on the drive shaft 213 of the motor 208 and the estimated flow rate calculated based on the rotation speed of the motor 208. By compensating with the estimated viscosity of the fluid L estimated by the viscosity estimating unit 260, the accuracy of the estimated value of the flow rate of the fluid L is improved.

Specifically, the flow rate of the fluid L is estimated based on the following formula (2). In the following equation (2), a symbol Qe represents an estimated flow rate value of the fluid L, a symbol T represents a torque of the motor 208, a symbol N represents a rotational speed of the motor 208, and symbols A, B, and C represents a coefficient.
Qe = A (T / N) + Bμ + C (2)

As described above, in this embodiment, the magnetic levitation type is corrected by correcting the estimated flow rate of the fluid L calculated based on the torque T and the rotation speed N of the motor 208 with the estimated viscosity value calculated by the viscosity estimating unit 260. The flow rate of the fluid L fed by the pump device 200 is obtained with high accuracy. The flow rate of the fluid L actually fed by the magnetic levitation pump device 200 is a value that can vary depending on the viscosity of the fluid L. For example, if the viscosity of the fluid L is low, it is easy to send the fluid L. Conversely, if the viscosity of the fluid L is high, it is difficult to send the fluid L. That is, the estimated flow rate value of the fluid L calculated based only on the torque T and the rotation speed N of the motor 208 varies depending on the magnitude of the viscosity value of the fluid L.

For this reason, in the present embodiment, the estimated flow rate of the fluid L calculated based on the torque T and the rotation speed N of the motor 208 is corrected with the estimated viscosity value calculated by the viscosity estimation unit 260, and the viscosity of the fluid L is thereby corrected. As a value based on this, the flow rate of the fluid L can be accurately calculated. That is, the accuracy in estimating the flow rate of the fluid L by the compensation by the viscosity estimated by the viscosity estimating unit 260 is improved. In particular, it is preferable to estimate the flow rate using the torque T of the motor 208 in order to achieve high accuracy in the flow rate estimation by eliminating the influence of copper loss and iron loss inside the motor 208.

In the present embodiment, the flow rate of the fluid L is accurately adjusted by correcting the estimated flow rate of the fluid L calculated based on the torque T and the rotation speed N of the motor 208 with the viscosity estimated by the viscosity estimation unit 260. Although calculated, the flow rate of the fluid L can also be obtained by correcting the estimated flow rate calculated based on the current value and power consumption of the motor 208 with the viscosity of the fluid L. That is, the flow rate estimation unit 261 estimates the flow rate of the fluid L based on at least one of the torque, current value, power consumption, and rotation speed of the motor 208 and the viscosity of the fluid L estimated by the viscosity estimation unit 260. . At that time, the viscosity μ of the fluid L may be estimated more accurately by using the torque, current value, and power consumption of the motor 208 together.

As described above, in this embodiment, the impeller 204 is forcibly microvibrated by applying an excitation current intentionally superimposed on the excitation current applied to the electromagnet 216 of the magnetic bearing portion 201 for a predetermined time. . Accordingly, the viscosity μ of the fluid L can be easily and accurately estimated based on the phase difference θ between the impeller displacement generated by the minute vibration and the alternating current and the amplitude ratio a / b. In addition, the viscosity μ of the fluid L can be estimated more easily and reliably without being restricted by the structure of the apparatus.

Further, in this embodiment, the flow rate estimation accuracy is improved by reflecting the estimated viscosity value of the fluid L estimated by the viscosity estimating unit 260 in the flow rate estimation of the fluid L. For this reason, by applying the magnetic levitation pump device 200 of this embodiment to a medical device such as a blood pump or an artificial heart, the flow rate of the fluid L to be fed can be accurately adjusted without installing an extra flow meter or the like. Since it can be estimated well, the safety of the patient who uses the medical device can be secured.

Next, a fluid viscosity estimation method using a magnetic levitation pump device according to another embodiment of the present invention will be described with reference to the drawings. FIG. 7 is a flow diagram showing an outline of a method for estimating the viscosity and flow rate of a fluid by a magnetic levitation pump device according to another embodiment of the present invention, and FIG. 8 shows another embodiment of the present invention. It is a flowchart which shows the outline of the other aspect of the estimation method of the viscosity and flow volume of the fluid by the magnetic levitation type pump apparatus which concerns. 7 shows a flow of a method for estimating the viscosity μ based on the phase difference θ, and FIG. 8 shows a flow of a method for estimating the viscosity μ based on the amplitude ratio a / b.

In the fluid viscosity and flow rate estimation method by the magnetic levitation pump apparatus 200 of the present embodiment, first, an alternating current in a predetermined frequency range is applied to the excitation current applied to the electromagnet 216 provided in the magnetic bearing unit 201 for a predetermined time (for example, , Applied for several seconds and superposed on the excitation current (AC current application step S31). Thus, in the present embodiment, the impeller 204 is forcibly vibrated by intentionally applying an alternating current for a predetermined time.

At that time, as described above, an alternating current having a frequency f at which the impeller can vibrate around the floating target position and an amplitude b within a range where the impeller 204 and the housing 202 do not contact each other is applied. That is, it is necessary to select an appropriate frequency f and amplitude b so that the impeller 204 does not come into contact with the housing 202 around the floating target position.

If the frequency of the alternating current applied is too high, even if the amplitude of the alternating current is maximized, the impeller 204 does not respond and does not vibrate, so the viscosity estimation method according to this embodiment cannot be implemented. For this reason, in the low frequency range (for example, 400 Hz or less) where the impeller 204 vibrates, by adjusting the amplitude of the alternating current appropriately, the impeller 204 and the housing 202 are adjusted so as not to contact each other. That is, in order to estimate the viscosity of the fluid L by the viscosity estimation method according to the present embodiment, the frequency f of the alternating current to be applied is selected to be a frequency that is low enough to obtain the vibration amplitude a of the impeller 204, In addition, the amplitude b of the alternating current needs to be adjusted within a range where the impeller 204 and the housing 202 do not contact each other.

The alternating current applied here may be an alternating current having a predetermined cycle such that the current value periodically fluctuates in the same manner as in the first embodiment described above. The sine wave shown in FIG. 4A, the rectangular wave shown in FIG. 4B, the triangular wave shown in FIG. 4C, and the sawtooth wave shown in FIG. 4D are applicable.

After the alternating current is applied, the displacement of the impeller due to the vibration of the impeller 204 is detected by the displacement sensor 220 (impeller displacement detection step S32). Then, the phase of the impeller displacement caused by the vibration of the impeller 204 generated by the application of the alternating current is plotted and recorded (recording step S33). Thereafter, the phase difference θ between the impeller displacement and the alternating current is calculated (calculation step S34), and the viscosity μ of the fluid L is estimated based on the phase difference θ (viscosity estimation step S35).

On the other hand, when the viscosity μ is detected by the amplitude ratio a / b, as shown in FIG. 8, the vibration of the impeller 204 generated by the application of the alternating current after the alternating current application step S41 and the impeller displacement detection step S42. The amplitude a of the impeller displacement due to is plotted and recorded (recording step S43). Then, the amplitude ratio a / b between the impeller displacement and the alternating current is calculated (calculation step S44), and the viscosity μ of the fluid L is estimated based on the amplitude ratio a / b (viscosity estimation step S45).

In this embodiment, the viscosity μ of the fluid L is estimated using the phase difference θ or the amplitude ratio a / b. However, if at least one of them is used, the viscosity μ can be estimated. Both may be used together to estimate the viscosity μ of the fluid L with higher accuracy.

Then, after detecting the torque and rotation speed of the motor 208 (motor data detection steps S36 and S46), the torque and rotation speed of the motor 208 detected by the torque meter 224 and the fluid L estimated in the viscosity estimation step S45. The flow rate of the fluid L is estimated based on the viscosity μ (flow rate estimation steps S37 and S47). In the flow rate estimation steps S37 and S47, the flow rate of the fluid L is estimated by compensating the estimated flow rate obtained from the torque and the rotation speed of the motor 208 with the viscosity μ of the fluid L estimated in the viscosity estimation steps S35 and S45. .

Thus, in the present embodiment, during the normal operation of the magnetic levitation pump device 200, the excitation current to the electromagnet 216 is calculated so that the impeller 204 does not shake from the target position (center of rotation axis, etc.). . On the other hand, when estimating the viscosity μ of the fluid L, the impeller 204 is forcibly vibrated by superimposing an alternating current having a constant frequency f on the excitation current for several seconds. Then, during the forced vibration of the impeller 204, the phase difference θ or the amplitude ratio a / b between the alternating current I of the frequency f and the impeller displacement X is calculated. As described above, since the phase difference theta and the amplitude ratio a / b change depending on the viscosity μ of the fluid, the relationship between θ and μ obtained experimentally in advance or the theoretically obtained θ and μ From the relational expression, the fluid viscosity μ is estimated.

For this reason, the viscosity estimation method by the magnetic levitation pump apparatus 200 of the present embodiment can easily estimate the viscosity μ of the fluid L without adding new hardware. Also, the viscosity estimation method by the magnetic levitation pump device 200 of the present embodiment is less dependent on the flow rate and does not need to block the flow rate, unlike the conventional method using the motor torque for viscosity estimation. Since there is no influence of loss, the fluid viscosity μ can be accurately estimated. Furthermore, the viscosity estimation method using the magnetic levitation pump apparatus 200 according to the present embodiment does not affect the measurement accuracy of the viscosity μ even if the gap between the impeller 204 and the housing 202 is large in principle. Accurate viscosity estimation is possible without being restricted by the above.

Also, in this embodiment, the accuracy in estimating the flow rate of the fluid L to be measured is improved by compensating with the viscosity estimated by the magnetic levitation pump device 200. For this reason, the viscosity estimation method and the flow rate estimation method by the magnetic levitation pump device 200 of this embodiment can be applied to various fields. For example, in a conventional circulation system such as an artificial artificial heart that is difficult to install a flow meter, there has been extensive research on estimating the flow rate from motor torque, etc., but the error greatly increases or decreases depending on the working fluid viscosity. The estimated viscosity value obtained by the viscosity estimation method by the magnetic levitation pump apparatus 200 of the present embodiment can be used for error correction of the flow rate estimation and applied to the flow rate estimation of the fluid L.

Furthermore, the state of the working fluid may be applied to online monitoring using the estimated viscosity value itself. For example, it can be applied to blood coagulation monitoring such as blood clot detection and prediction in blood pumps and artificial hearts, and quality control of ultrapure water in semiconductor and food manufacturing. That is, it can be applied as a magnetic levitation type continuous flow blood pump for extracorporeal circulation, a magnetic levitation type artificial heart for implantation in the body, and an ultra-clean magnetic levitation type pump for semiconductor manufacturing and food manufacturing.

Note that, in another embodiment (second embodiment) of the present invention, similarly to one embodiment (first embodiment) of the present invention, the present invention is applied to a magnetic levitation pump device including a centrifugal impeller. However, the present invention is also applicable to a magnetic levitation pump device including an axial flow type impeller 124 (see FIG. 5D) and a mixed flow type impeller 134 (see FIG. 5E). That is, the magnetic levitation pump device 200 of the present embodiment can be applied to a magnetic levitation type continuous flow pump regardless of whether it is a centrifugal type, an axial flow type, or a diagonal flow type, as in the first embodiment.

Next, an example of fluid viscosity estimation by the magnetic levitation pump device 100 according to an embodiment of the present invention will be described with reference to the drawings.

In order to demonstrate the operation and effect of the viscosity estimation method by the magnetic levitation pump apparatus 100 (see FIG. 1) according to one embodiment of the present invention, the present embodiment is a magnetic levitation pump apparatus 100 having the configuration shown in FIG. It was used. The configuration is omitted because it has been described above.

The impeller of the present embodiment is passively supported by a restoring force due to electromagnetic force in the axial direction (vertical direction), but in the radial direction (horizontal direction), the magnet of a permanent magnet built in the rotor of the impeller. The suction force works and is attracted to the wall surface of the housing. Therefore, in this embodiment, the impeller is stably levitated by feeding back the impeller position information with a displacement sensor and adjusting the electromagnetic force in the radial direction with an electromagnet.

FIG. 9 is an explanatory diagram showing the relationship between the impeller displacement waveform and the phase and amplitude of the applied alternating current waveform in an example of fluid viscosity estimation by the magnetic levitation pump device according to one embodiment of the present invention. When the impeller levitation target position is changed to a sinusoidal shape by the applied current control unit in the CPU (calculation unit) in a state where the impeller is stably magnetically levitated around the rotation axis, as shown in the lower graph of FIG. An electromagnet current, which is an alternating current, is supplied from the control unit and superimposed on the exciting current to the electromagnet.

In this way, by applying an alternating current and superimposing it with the exciting current, the impeller also vibrates in a sine wave like the applied alternating current, as shown in the graph on the upper end side of FIG. In this embodiment, the phase difference θ between the alternating current (electromagnet current) I and the impeller displacement X applied at this time is obtained by the calculation unit. At that time, an amplitude ratio a / b which is a ratio of the amplitude a of the impeller displacement and the amplitude b of the alternating current is also obtained by the calculation unit.

FIG. 10 is an explanatory diagram showing the relationship between the amplitude ratio and phase difference between the impeller displacement waveform and the applied current waveform and the frequency of the applied current in this example. The relationship between the amplitude ratio a / b and the frequency of the impeller vibration generated by applying the applied AC current is shown in a graph on the upper side of FIG. 10, and the relationship between the phase difference θ and the frequency of the vibration is shown on the lower side of FIG. Is shown in the graph.

As shown in FIG. 10, when measured with five types of glycerin aqueous solutions having different viscosities (0 wt% = water, 20 wt%, 40 wt%, 60 wt%, 70 wt%), both the amplitude ratio a / b and the phase difference θ oscillate. When the frequency is low, the sensitivity to the viscosity μ is low. On the other hand, as shown in FIG. 10, it can be seen that the sensitivity of the amplitude ratio a / b and the phase difference θ with respect to the viscosity μ is improved when the frequency of vibration becomes a large value of about 30 Hz or more. In particular, it was confirmed that the sensitivity of the phase difference θ with respect to the viscosity μ was maximum when the vibration frequency was 70 Hz. Therefore, in this example, a frequency of f = 70 Hz was used for viscosity estimation.

Next, FIG. 11 shows the relationship between the viscosity and the phase difference θ at a vibration frequency of 70 Hz. In this example, the impeller rotational speed was 2000 rpm, the flow rate was 5 L / min, and measurement was performed with three types of glycerin aqueous solutions (0 wt% = water, 30 wt%, 50 wt%) having different viscosities. Since the viscosity μ and the phase difference θ are in a linear relationship, constants A ₀ and B ₀ in the following formula (3) are identified in a preliminary experiment.
μ = A ₀ θ + B ₀ (3)

Since the above constants A ₀ and B ₀ differ for each impeller rotational speed, the constants A ₀ and B ₀ are identified at each rotational speed, or the rotational speed is set to a specific value (this time, 2000 rpm). When the flow rate is changed at 2000 rpm for three types of glycerin aqueous solutions having different viscosities (0 wt% = water, 30 wt%, 50 wt%), as shown in FIG. It can be seen that it is sufficiently small and negligible compared to.

Therefore, at the time of viscosity estimation, θ when the impeller is vibrated at 70 Hz is calculated online, and is substituted into the above equation (1), and the result is shown in FIG. The horizontal axis of the graph shown in FIG. 13 indicates the viscosity of the working fluid actually measured with a viscometer, and the vertical axis indicates the viscosity of the working fluid estimated by the present embodiment. Some variation is observed because the flow rate was changed from 0 to 8 L / min. In this example, in the measurement range from 0.75 mPa · s to 3.27 mPa · s, ± 0.14 mPa・ Realized the estimation accuracy of s. That is, it was proved that the viscosity estimation method of the present example can achieve a good fluid viscosity estimation.

Next, an example of fluid viscosity estimation by the magnetic levitation pump device 200 according to another embodiment (second embodiment) of the present invention will be described with reference to the drawings.

The present example is a magnetic levitation pump configured as shown in FIG. 6 in order to demonstrate the operation and effect of the viscosity estimation method by the magnetic levitation pump apparatus 200 (see FIG. 6) according to another embodiment of the present invention. An apparatus 200 was used. Specifically, a flow meter is attached to the outflow portion 202d of the magnetic levitation pump device 200, the working fluid discharged from the outflow portion 202d is supplied to a reservoir provided in the thermostatic bath, and the magnetic levitation pump is supplied from the reservoir. The relationship between the measured flow rate and the estimated flow rate was examined by returning the working fluid to the inflow portion 202c of the apparatus 200. The configuration of the magnetic levitation pump device 200 has been described above, and will not be described.

In this example, glycerin aqueous solutions having different viscosities described in Table 1 below are used as working fluids for which the flow rate is to be estimated, and are fed by a magnetic levitation pump device 200 according to another embodiment of the present invention. The flow rate of the working fluid was measured 8 times, 2 times each for the case of no viscosity compensation and 2 for the estimated viscosity.

In the case where there is no viscosity compensation, the flow rate is estimated based on the formula (2) by compensating the viscosity μ of the formula (2) described above with the average value μa = 3.17 mPa · s of the viscosity of the working fluid described above. did. On the other hand, in the case of compensating with the estimated viscosity, the flow rate is estimated based on the equation (2) by compensating the viscosity μ of the above-described equation (2) with the estimated viscosity μe calculated by the following equation (4). did. Since the estimated viscosity μe in the following equation (4) is linearly related to the electromagnet current and the phase difference φ between the impeller displacements, the constant of the following equation (4) is the same as the above equation (3). Assume that k ₁ and k ₀ are obtained after identification in a preliminary experiment.
μe = k ₁ φ + k ₀ (4)

FIG. 14 is an explanatory diagram showing the relationship between the measured flow rate and the estimated flow rate in an example of fluid flow rate estimation by the magnetic levitation pump device 200 according to another embodiment of the present invention. In FIG. 14, the horizontal axis indicates the actual flow rate Q actually measured by the flow meter, and the vertical axis indicates the estimated flow rate Qe.

As shown in FIG. 14, it can be seen that there is a variation in the value of the estimated flow rate Qe with respect to the actual flow rate when there is no viscosity compensation. On the other hand, in the case of compensating with the estimated viscosity, it can be seen that the variation in the value of the estimated flow rate Qe with respect to the actually measured flow rate becomes smaller than in the case where there is no viscosity compensation. Therefore, when the flow rate of the fluid sent by the magnetic levitation pump device 200 is compensated with the estimated viscosity, the estimated value of the flow rate is less varied than when there is no viscosity compensation, and closer to the actually measured value. You can see that it fits. That is, when estimating the flow rate of the working fluid in the magnetic levitation pump apparatus 200 according to another embodiment of the present invention, by compensating with the estimated viscosity μ obtained by the viscosity estimation by the magnetic levitation pump apparatus 200. It can be seen that the flow rate of the fluid close to the actually measured value can be estimated.

Although the embodiments and examples of the present invention have been described in detail as described above, it will be understood by those skilled in the art that many modifications can be made without departing from the novel matters and effects of the present invention. It will be easy to understand. Therefore, all such modifications are included in the scope of the present invention.

For example, a term described together with a different term having a broader meaning or the same meaning at least once in the specification or the drawings can be replaced with the different term in any part of the specification or the drawings. Further, the configuration and operation of the magnetic levitation pump device are not limited to those described in the embodiments and examples of the present invention, and various modifications can be made.

100, 200 Magnetic levitation pump device, 101, 201 Magnetic bearing part, 102, 202 Housing, 102a, 202a Side wall part, 102b, 202b Bottom part, 102b1, 202b1 Convex part, 102c, 202c Inflow part, 102d, 202d Outflow part, 104, 204 (centrifugal type) impeller, 106, 206 rotor, 106a, 206a outer peripheral surface, 106b, 206b concave portion, 106b1, 206b1 inner peripheral surface, 108, 208 motor (rotation drive unit), 110, 112, 114, 210, 212, 214 Permanent magnet, 113, 213 Drive shaft, 116, 216 Electromagnet, 118, 218 Current sensor, 120, 220 Displacement sensor, 122, 222 Casing, 124 Axial flow type impeller, 134 Diagonal flow type impeller, 150, 2 0 control unit, 152, 252 CPU (calculation unit), 154, 254 applied current control unit, 156, 256 impeller displacement recording unit, 158, 258 calculation unit, 160, 260 viscosity estimation unit, 162, 262 applied current adjustment unit, 164, 264 Motor control unit, 166, 266 Storage unit, 224 Torque meter, S11, S21, S31, S41 AC current application process, S12, S22, S32, S42 Impeller displacement detection process, S13, S23, S33, S43 Recording process , S14, S24, S34, S44 Calculation step, S15, S25, S35, S45 Viscosity estimation step, S36, S46 Motor data detection step, S37, S47 Flow rate estimation step

Claims (9)

1. A magnetic levitation pump device that transfers the fluid while rotating the impeller by magnetic levitation in a housing having a fluid inflow portion and an outflow portion,
   A rotary drive unit that rotates in combination with the impeller in a non-contact manner by a magnetic force;
   A magnetic bearing portion that supports the impeller in a non-contact manner by the magnetic force;
   An applied current control unit for controlling an applied current to an electromagnet provided at a position facing a permanent magnet built in a rotor of the impeller of the magnetic bearing unit;
   A current sensor for detecting the magnitude of the applied current;
   A displacement sensor for detecting the displacement of the impeller;
   When the applied current control unit controls the applied current so that an alternating current in a predetermined frequency range is superimposed on an excitation current to the electromagnet for a predetermined time, the impeller detected by the displacement sensor A calculation unit that calculates at least one of a phase difference between the impeller displacement due to vibration and the alternating current or an amplitude ratio between the impeller displacement and the alternating current;
   A magnetic levitation pump device comprising: a viscosity estimation unit that estimates the viscosity of the fluid based on at least one of the phase difference or the amplitude ratio calculated by the calculation unit.
2. The applied current control unit, when applying the alternating current and superimposing the excitation current, a frequency at which the impeller can vibrate around a floating target position, and an amplitude within a range where the impeller and the housing do not contact each other. The magnetic levitation pump device according to claim 1, wherein an alternating current having the above is applied.
3. The magnetic levitation pump device according to claim 2, wherein the frequency is a value close to a value calculated by the following equation.
   

   
4. The viscosity estimating unit estimates the viscosity based on prior experimental data related to the relationship between the phase difference and the viscosity, or based on a relational expression between the phase difference and the viscosity obtained theoretically in advance. The magnetic levitation pump device according to any one of claims 1 to 3.
5. The magnetic levitation pump device according to any one of claims 1 to 4, wherein the impeller has any one of a centrifugal type, an axial flow type, and a mixed flow type.
6. A flow rate estimating unit that estimates the flow rate of the fluid based on at least one of the torque, current value, power consumption, and rotation speed of the rotation driving unit and the viscosity estimated by the viscosity estimating unit; The magnetic levitation pump device according to claim 1, wherein the levitation pump device is a magnetic levitation pump device according to claim 1.
7. A fluid viscosity estimation method using a magnetic levitation pump device that transfers the fluid while magnetically levitating and rotating an impeller in a housing having a fluid inflow portion and an outflow portion,
   An alternating current application step of applying and superimposing an alternating current in a predetermined frequency range on an exciting current applied to an electromagnet provided at a position facing a permanent magnet built in the rotor of the impeller;
   An impeller displacement detection step of detecting an impeller displacement due to vibration of the impeller after applying the alternating current;
   A recording step of recording at least one of a phase or an amplitude of the impeller displacement due to the vibration;
   A calculation step of calculating at least one of a phase difference or an amplitude ratio between the impeller displacement and the alternating current;
   And a viscosity estimating step of estimating the viscosity of the fluid based on at least one of the phase difference and the amplitude ratio.
8. A fluid flow rate estimation method using a magnetic levitation pump device that moves the impeller while magnetically levitating and rotating in a housing having a fluid inflow portion and an outflow portion,
   An alternating current application step of applying and superimposing an alternating current in a predetermined frequency range on an exciting current applied to an electromagnet provided at a position facing a permanent magnet built in the rotor of the impeller;
   An impeller displacement detection step of detecting an impeller displacement due to vibration of the impeller after applying the alternating current;
   A recording step of recording at least one of a phase or an amplitude of the impeller displacement due to the vibration;
   A calculation step of calculating at least one of a phase difference or an amplitude ratio between the impeller displacement and the alternating current;
   A viscosity estimating step of estimating the viscosity of the fluid based on at least one of the phase difference and the amplitude ratio;
   A flow rate estimating step for estimating a flow rate of the fluid based on at least one of torque, current value, power consumption, and rotation speed of the rotation drive unit that rotates the impeller, and the viscosity estimated in the viscosity estimation step; ,
   A fluid flow rate estimating method using a magnetically levitated pump device.
9. In the flow rate estimation step, the flow rate is estimated by compensating an estimated flow rate obtained from the torque of the rotation drive unit and the rotation speed with the viscosity estimated in the viscosity estimation step. Item 9. A method for estimating a fluid flow rate by the magnetic levitation pump device according to Item 8.

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